ANSY S Fluen t User's G uide Release 2019 R3 ANSY S, Inc. August 2019 Southp ointe 2600 ANSY S Drive Canonsbur g, PA 15317 ANSY S, Inc. and ANSY S Europe,ansy sinfo@ansy s.com Ltd. are ULhttp://www .ansy s.comregist ered ISO(T) 724-746-3304 (F) 724-514-94949001: 2015 companies .Copyright and Trademar k Inf ormation © 2019 ANSY S, Inc. Unauthor ized use , distr ibution or duplic ation is pr ohibit ed. ANSY S, ANSY S Workbench, AUTODYN, CFX, FLUENT and an y and all ANSY S, Inc. brand , produc t, service and f eature names , logos and slo gans ar e regist ered tr ademar ks or tr ademar ks of ANSY S, Inc. or its subsidiar ies lo cated in the United S tates or other c oun tries. ICEM CFD is a tr ademar k used b y ANSY S, Inc. under lic ense . CFX is a tr ademar k of S ony Corporation in Japan. All other br and , produc t, service and f eature names or tr ademar ks ar e the pr operty of their r espective owners . FLEXlm and FLEXnet ar e trademar ks of F lexera Software LL C. Disclaimer N otic e THIS ANSY S SOFT WARE PR ODUCT AND PR OGR AM DOCUMENT ATION INCL UDE TRADE SECRET S AND ARE C ONFID- ENTIAL AND PR OPRIET ARY PR ODUCT S OF ANSY S, INC., ITS SUBSIDIARIES, OR LICENSORS. The sof tware pr oduc ts and do cumen tation ar e fur nished b y ANSY S, Inc., its subsidiar ies, or affilia tes under a sof tware lic ense agr eemen t that contains pr ovisions c oncerning non-disclosur e, copying , length and na ture of use , complianc e with e xporting laws, warranties, disclaimers , limita tions of liabilit y, and r emedies , and other pr ovisions .The sof tware pr oduc ts and do cumen tation ma y be used , disclosed , transf erred, or c opied only in acc ordanc e with the t erms and c onditions of tha t sof tware lic ense agr eemen t. ANSY S, Inc. and ANSY S Europe, Ltd. are UL r egist ered ISO 9001: 2015 c ompanies . U.S. Governmen t Rights For U.S. Governmen t users , except as sp ecific ally gr anted b y the ANSY S, Inc. software lic ense agr eemen t, the use , duplic ation, or disclosur e by the U nited S tates G overnmen t is subjec t to restrictions sta ted in the ANSY S, Inc. software lic ense agr eemen t and F AR 12.212 (f or non-DOD lic enses). Third-Party Software See the legal inf ormation in the pr oduc t help files f or the c omplet e Legal N otice for ANSY S pr oprietar y sof tware and thir d-par ty sof tware. If you ar e unable t o acc ess the L egal N otice, contact ANSY S, Inc. Published in the U.S.A.Table of C ontents I. Getting S tarted........................................................................................................................................1 1. Introduc tion t o ANSY S Fluen t...........................................................................................................3 1.1.The ANSY S Product Impr ovemen t Program.................................................................................5 1.2. Program C apabilities ...................................................................................................................8 1.3. Known Limita tions in ANSY S Fluen t 2019 R3 ..............................................................................10 2. Basic S teps f or CFD A naly sis using ANSY S Fluen t...........................................................................25 2.1. Steps in S olving Your CFD P roblem ............................................................................................25 2.2. Planning Your CFD A naly sis.......................................................................................................25 3. Guide t o a S uccessful S imula tion U sing ANSY S Fluen t...................................................................31 4. Starting and E xecuting ANSY S Fluen t.............................................................................................33 4.1. Starting ANSY S Fluen t...............................................................................................................33 4.1.1. Starting ANSY S Fluen t Using F luen t Launcher ...................................................................33 4.1.1.1. Setting G ener al Options in F luen t Launcher .............................................................36 4.1.1.2. Single-P recision and D ouble-P recision S olvers..........................................................38 4.1.1.3. Setting P arallel Options in F luen t Launcher ..............................................................39 4.1.1.4. Setting R emot e Options in F luen t Launcher .............................................................41 4.1.1.5. Setting Scheduler Options in F luen t Launcher ..........................................................42 4.1.1.6. Setting En vironmen t Options in F luen t Launcher .....................................................44 4.1.2. Starting ANSY S Fluen t on a Windo ws System....................................................................45 4.1.3. Starting ANSY S Fluen t on a Linux S ystem..........................................................................46 4.1.4. Command Line S tartup Options .......................................................................................47 4.1.4.1. ACT Option .............................................................................................................49 4.1.4.2. Applic ation Option ..................................................................................................49 4.1.4.3. Applic ation Scr ipt Option ........................................................................................49 4.1.4.4. Graphics Options .....................................................................................................49 4.1.4.5. Meshing M ode Option .............................................................................................51 4.1.4.6. Performanc e Options ...............................................................................................51 4.1.4.7. Parallel Options .......................................................................................................51 4.1.4.8. Postpr ocessing Option ............................................................................................52 4.1.4.9. Remot e Visualiza tion Options ..................................................................................53 4.1.4.10. Scheduler Options .................................................................................................53 4.1.4.11. Version, Release Options , and En vironmen t Variables ..............................................53 4.1.4.12. System C oupling Options ......................................................................................54 4.1.4.13. Other S tartup Options ...........................................................................................55 4.2. Running ANSY S Fluen t in B atch M ode.......................................................................................55 4.2.1. Background Ex ecution on Linux S ystems ..........................................................................55 4.2.2. Background Ex ecution on Windo ws Systems ....................................................................56 4.2.3. Batch Ex ecution Options ..................................................................................................57 4.3. Switching B etween M eshing and S olution M odes ......................................................................59 4.4. Check pointing an ANSY S Fluen t Simula tion ...............................................................................59 4.5. Cleaning U p Processes F rom an ANSY S Fluen t Simula tion ..........................................................60 4.6. Exiting ANSY S Fluen t................................................................................................................61 Glossar y of Terms..................................................................................................................................63 II. Meshing M ode......................................................................................................................................67 1. Introduc tion t o M eshing M ode in F luen t........................................................................................69 1.1. Meshing A pproach ...................................................................................................................69 1.2. Meshing M ode C apabilities .......................................................................................................69 2. Starting F luen t in M eshing M ode...................................................................................................71 2.1. Starting the D ual P rocess B uild ..................................................................................................71 2.2. Dynamic ally S pawning P rocesses B etween F luen t Meshing and F luen t Solution M odes .............72 iiiRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.3. Graphic al U ser In terface.................................................................................................................75 3.1. User In terface Comp onen ts.......................................................................................................76 3.1.1. The R ibbon......................................................................................................................76 3.1.2. The Workflow Tab.............................................................................................................81 3.1.3. The Outline View Tab........................................................................................................81 3.1.4. The G raphics Windo w.......................................................................................................89 3.1.5. Quick S earch....................................................................................................................89 3.1.6. The C onsole .....................................................................................................................90 3.1.7. The Toolbars .....................................................................................................................90 3.1.7.1. Pointer Tools............................................................................................................91 3.1.7.2. View Tools...............................................................................................................92 3.1.7.3. Projec tion ................................................................................................................92 3.1.7.4. Displa y Options .......................................................................................................93 3.1.7.5. Additional D ispla y Options ......................................................................................93 3.1.7.6. Filter Toolbar ...........................................................................................................93 3.1.7.7. CAD Tools................................................................................................................94 3.1.7.8. Tools.......................................................................................................................94 3.1.7.9. Context Toolbar .......................................................................................................94 3.1.8. ACT S tart Page .................................................................................................................95 3.2. Customizing the U ser In terface.................................................................................................95 3.3. Setting U ser P references/Options ..............................................................................................95 3.4. Using the H elp S ystem..............................................................................................................96 3.4.1. Help f or Text Interface Commands ....................................................................................97 3.4.2. Obtaining a Listing of O ther Lic ense U sers ........................................................................97 4.Text User In terface..........................................................................................................................99 5. Reading and Writing F iles .............................................................................................................101 5.1. Shortcuts f or R eading and Writing F iles ...................................................................................101 5.1.1. Binar y Files .....................................................................................................................101 5.1.2. Reading and Writing C ompr essed F iles ...........................................................................101 5.1.2.1. Reading C ompr essed F iles .....................................................................................102 5.1.2.2. Writing C ompr essed F iles .......................................................................................102 5.1.3. Tilde Expansion (LINUX S ystems Only) .............................................................................103 5.1.4. Disabling the O verwrite Confir mation P rompt ................................................................103 5.2. Mesh F iles ...............................................................................................................................103 5.2.1. Reading M esh F iles.........................................................................................................104 5.2.1.1. Reading M ultiple M esh F iles...................................................................................105 5.2.1.2. Reading 2D M esh F iles in the 3D Version of F luen t..................................................105 5.2.2. Reading B oundar y Mesh F iles .........................................................................................105 5.2.3. Reading F aceted G eometr y Files fr om ANSY S Workbench in F luen t.................................105 5.2.4. Appending M esh F iles ....................................................................................................105 5.2.5. Writing M esh F iles ..........................................................................................................106 5.2.6. Writing B oundar y Mesh F iles ..........................................................................................106 5.3. Case F iles ................................................................................................................................106 5.3.1. Reading C ase F iles ..........................................................................................................107 5.3.2. Writing C ase F iles ...........................................................................................................107 5.3.2.1. Writing F iles U sing Hier archic al D ata Format (HDF) .................................................108 5.4. Reading and Writing S ize-Field F iles.........................................................................................108 5.5. Reading Scheme S ource Files ..................................................................................................109 5.6. Creating and R eading J ournal F iles ..........................................................................................109 5.7. Creating Transcr ipt F iles ..........................................................................................................111 5.8. Reading and Writing D omain F iles ...........................................................................................111 5.9. Imp orting F iles........................................................................................................................112 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. ivUser's G uide5.9.1. Imp orting C AD F iles .......................................................................................................112 5.10. Saving P icture Files ...............................................................................................................119 5.10.1. Using the S ave Picture Dialog Box.................................................................................120 6.Working With F luen t Guided Workflo ws.......................................................................................123 6.1. Getting S tarted with the F luen t Guided Workflows..................................................................123 6.1.1. Prerequisit es for the F luen t Guided Workflows................................................................123 6.1.2. Limita tions of the F luen t Guided Workflows....................................................................124 6.1.3. Customizing Workflows..................................................................................................128 6.1.4. Understanding Task S tates..............................................................................................128 6.1.5. Operating on Tasks .........................................................................................................129 6.1.6. Grouping Tasks ...............................................................................................................129 6.1.7. Editing Tasks ..................................................................................................................129 6.1.8. Saving and L oading Workflows.......................................................................................130 6.1.9. Setting P references for Workflows...................................................................................130 6.1.10. Getting H elp f or Workflow Tasks ....................................................................................132 6.2. Using the Watertigh t Geometr y Workflow................................................................................132 6.2.1. Imp orting C AD G eometr ies............................................................................................132 6.2.2. Adding L ocal Sizing ........................................................................................................134 6.2.3. Creating Sur face Meshes ................................................................................................136 6.2.4. Setting U p Periodic B oundar ies......................................................................................139 6.2.5. Descr ibing the G eometr y...............................................................................................140 6.2.6. Applying S hare Topology................................................................................................141 6.2.6.1. Troublesho oting G ap M arking................................................................................142 6.2.7. Enclosing F luid R egions ..................................................................................................144 6.2.8. Creating R egions ............................................................................................................147 6.2.9. Updating R egions ..........................................................................................................148 6.2.10. Creating a Volume M esh ...............................................................................................149 6.2.11. Updating B oundar ies....................................................................................................152 6.2.12. Impr oving the Sur face Mesh .........................................................................................153 6.2.13. Adding B oundar y Types................................................................................................154 6.2.14. Impr oving the Volume M esh ........................................................................................154 6.2.15. Modifying M esh R efinemen t.........................................................................................155 6.2.16. Running C ustom J ournal C ommands ............................................................................156 6.3. Using the F ault-t oler ant Meshing Workflow.............................................................................156 6.3.1. Imp orting C AD G eometr ies and M anaging C AD P arts.....................................................157 6.3.1.1. Appending C AD F iles .............................................................................................159 6.3.1.2. Working with the C AD M odel Tree..........................................................................160 6.3.1.3. Working with the M eshing M odel Tree...................................................................162 6.3.1.4. Setting P roperties f or M eshing M odel O bjec ts........................................................164 6.3.1.4.1. Faceting C onsider ations ................................................................................166 6.3.1.5. Setting D ispla y Options f or C AD M odel and M eshing O bjec ts.................................168 6.3.1.6. Using H ot Ke y Shortcuts in the M odel Trees and the G raphics Windo w....................168 6.3.2. Descr ibing the G eometr y and the F low...........................................................................169 6.3.3. Enclosing F luid R egions ..................................................................................................170 6.3.4. Creating Ex ternal F low Boundar ies..................................................................................171 6.3.5. Creating L ocal Refinemen t Regions .................................................................................173 6.3.6. Iden tifying C onstr uction Sur faces...................................................................................177 6.3.7. Extracting E dge F eatures................................................................................................178 6.3.8. Adding Thick ness t o Your G eometr y...............................................................................182 6.3.9. Creating P orous R egions .................................................................................................184 6.3.10. Iden tifying R egions ......................................................................................................186 6.3.11. Defining L eakage Thresholds ........................................................................................188 vRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide6.3.12. Updating Your R egion S ettings .....................................................................................190 6.3.13. Choosing M esh C ontrol Options ...................................................................................191 6.3.14. Setting U p Size Controls...............................................................................................192 6.3.15. Gener ating the Sur face Mesh ........................................................................................193 6.3.16. Setting U p Boundar y La yer C ontrols.............................................................................194 6.3.17. Gener ating the Volume M esh ........................................................................................196 6.3.18. Separ ating C ontacts.....................................................................................................196 7. CAD A ssemblies ............................................................................................................................199 7.1. CAD A ssemblies Tree...............................................................................................................199 7.1.1. FMDB F ile.......................................................................................................................200 7.1.2. CAD En tity Path..............................................................................................................200 7.1.3. CAD A ssemblies Tree Options .........................................................................................201 7.2.Visualizing C AD En tities ...........................................................................................................202 7.3. Updating C AD En tities ............................................................................................................202 7.4. Manipula ting C AD En tities ......................................................................................................203 7.4.1. Creating and M odifying G eometr y/M esh O bjec ts............................................................203 7.4.2. Managing Lab els............................................................................................................204 7.4.3. Setting C AD En tity States................................................................................................204 7.4.4. Modifying C AD En tities ...................................................................................................205 7.5. CAD A ssociation .....................................................................................................................205 8. Size Func tions and Sc oped S izing .................................................................................................207 8.1.Types of S ize Functions or Sc oped S izing C ontrols....................................................................208 8.1.1. Curvature.......................................................................................................................208 8.1.2. Proximit y.......................................................................................................................209 8.1.3. Meshed ..........................................................................................................................213 8.1.4. Har d..............................................................................................................................213 8.1.5. Soft................................................................................................................................214 8.1.6. Body of Influenc e...........................................................................................................214 8.2. Defining S ize Functions ...........................................................................................................215 8.2.1. Creating D efault S ize Functions ......................................................................................216 8.3. Defining Sc oped S izing C ontrols..............................................................................................217 8.3.1. Size Control Files ............................................................................................................217 8.4. Computing the S ize Field ........................................................................................................217 8.4.1. Size Field F iles ................................................................................................................218 8.4.2. Using S ize Field F ilters....................................................................................................218 8.4.3. Visualizing S izes.............................................................................................................219 8.5. Using the S ize Field .................................................................................................................220 9. Objec ts and M aterial P oints..........................................................................................................223 9.1. Objec ts...................................................................................................................................223 9.1.1. Objec t Attribut es............................................................................................................224 9.1.1.1. Creating O bjec ts....................................................................................................226 9.1.2. Objec t En tities ................................................................................................................227 9.1.2.1. Using F ace Zone Lab els..........................................................................................227 9.1.3. Managing O bjec ts .........................................................................................................228 9.1.3.1. Using hotk eys and onscr een t ools..........................................................................229 9.1.3.1.1. Creating O bjec ts for C AD En tities ..................................................................229 9.1.3.1.2. Creating O bjec ts for U nreferenced Z ones ......................................................229 9.1.3.1.3. Creating M ultiple O bjec ts..............................................................................230 9.1.3.1.4. Easy O bjec t Creation and M odific ation ..........................................................230 9.1.3.1.5. Changing O bjec t Properties ..........................................................................231 9.1.3.1.6. Automa tic A lignmen t of O bjec ts...................................................................231 9.1.3.1.7. Remeshing G eometr y Objec ts.......................................................................231 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. viUser's G uide9.1.3.1.8. Creating E dge Z ones .....................................................................................232 9.1.3.2. Using the M anage O bjec ts D ialog Box....................................................................232 9.1.3.2.1. Defining O bjec ts...........................................................................................232 9.1.3.2.2. Objec t Manipula tion Op erations ...................................................................233 9.1.3.2.3. Objec t Transf ormation Op erations .................................................................234 9.2. Material P oints........................................................................................................................235 9.2.1. Creating M aterial P oints.................................................................................................237 10. Objec t-Based S urface M eshing ...................................................................................................239 10.1. Sur face Mesh P rocesses .........................................................................................................239 10.2. Prepar ing the G eometr y........................................................................................................241 10.2.1. Using a B ounding B ox..................................................................................................241 10.2.2. Closing A nnular G aps in the G eometr y..........................................................................242 10.2.3. Patching Tools..............................................................................................................242 10.2.3.1. Using the P atch Options D ialog Box.....................................................................243 10.2.3.2. Using the L oop S elec tion Tool..............................................................................246 10.2.4. Using U ser-D efined G roups ..........................................................................................247 10.3. Diagnostic Tools....................................................................................................................247 10.3.1. Geometr y Issues ...........................................................................................................248 10.3.2. Face Connec tivit y Issues ...............................................................................................248 10.3.3. Qualit y Check ing..........................................................................................................250 10.3.4. Summar y.....................................................................................................................251 10.4. Connec ting O bjec ts..............................................................................................................251 10.4.1. Using the Join/In tersec t Dialog Box.............................................................................254 10.4.2. Using the Join Dialog Box.............................................................................................255 10.4.3. Using the Intersec t Dialog Box.....................................................................................256 10.5. Advanced Options ................................................................................................................256 10.5.1. Objec t Managemen t....................................................................................................256 10.5.2. Remo ving G aps B etween M esh O bjec ts........................................................................257 10.5.3. Remo ving Thick ness in M esh O bjec ts............................................................................258 10.5.4. Sewing O bjec ts............................................................................................................260 10.5.4.1. Resolving Thin R egions ........................................................................................262 10.5.4.2. Processing S lits....................................................................................................262 10.5.4.3. Remo ving Voids ...................................................................................................262 11. Objec t-Based Volume M eshing ...................................................................................................263 11.1. Volume M esh P rocess............................................................................................................263 11.2. Volumetr ic Region M anagemen t...........................................................................................264 11.2.1. Computing and Verifying R egions .................................................................................265 11.2.2. Volumetr ic Region Op erations ......................................................................................266 11.3. Gener ating the Volume M esh ................................................................................................268 11.3.1. Meshing A ll Regions C ollec tively U sing A uto Mesh ........................................................268 11.3.2. Meshing R egions S elec tively U sing A uto Fill Volume ......................................................271 11.4. Cell Z one Options .................................................................................................................272 12. Manipula ting the B oundar y M esh ..............................................................................................273 12.1. Manipula ting B oundar y Nodes ..............................................................................................273 12.1.1. Free and I sola ted N odes ...............................................................................................273 12.2. Intersec ting B oundar y Zones .................................................................................................274 12.2.1. Intersec ting Z ones ........................................................................................................275 12.2.2. Joining Z ones ...............................................................................................................276 12.2.3. Stitching Z ones ............................................................................................................278 12.2.4. Using the In tersec t Boundar y Zones D ialog Box............................................................279 12.2.5. Using S hortcut Ke ys/Icons ............................................................................................280 12.3. Modifying the B oundar y Mesh ..............................................................................................280 viiRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide12.3.1. Using the M odify B oundar y Dialog Box.........................................................................280 12.3.2. Operations P erformed: Modify B oundar y Dialog Box.....................................................281 12.3.3. Locally R emeshing a B oundar y Zone or F aces................................................................287 12.3.4. Moving N odes ..............................................................................................................288 12.4. Impr oving B oundar y Sur faces...............................................................................................288 12.4.1. Impr oving the B oundar y Sur face Qualit y.......................................................................288 12.4.2. Smoothing the B oundar y Sur face.................................................................................289 12.4.3. Swapping F ace Edges ...................................................................................................289 12.5. Refining the B oundar y Mesh .................................................................................................289 12.5.1. Procedur e for R efining B oundar y Zones ........................................................................289 12.6. Creating and M odifying F eatures...........................................................................................291 12.6.1. Creating E dge Z ones ....................................................................................................292 12.6.2. Modifying E dge Z ones ..................................................................................................295 12.6.3. Using the F eature Modify D ialog Box............................................................................296 12.7. Remeshing B oundar y Zones ..................................................................................................298 12.7.1. Creating E dge Z ones ....................................................................................................298 12.7.2. Modifying E dge Z ones ..................................................................................................299 12.7.3. Remeshing B oundar y Face Zones .................................................................................299 12.7.4. Using the Sur face Retriangula tion D ialog Box...............................................................300 12.8. Faceted S titching of B oundar y Zones .....................................................................................301 12.9. Triangula ting B oundar y Zones ...............................................................................................302 12.10. Separ ating B oundar y Zones ................................................................................................303 12.10.1. Separ ating F ace Zones using H otkeys.........................................................................303 12.10.2. Using the S epar ate Face Zones dialo g box...................................................................304 12.11. Projec ting B oundar y Zones .................................................................................................307 12.12. Creating G roups ..................................................................................................................307 12.13. Manipula ting B oundar y Zones ............................................................................................308 12.14. Manipula ting B oundar y Conditions .....................................................................................309 12.15. Creating Sur faces................................................................................................................310 12.15.1. Creating a B ounding B ox............................................................................................310 12.15.1.1. Using the B ounding B ox Dialog Box...................................................................310 12.15.1.2. Using the C onstr uct Geometr y Tool....................................................................311 12.15.2. Creating a P lanar Sur face Mesh ...................................................................................312 12.15.2.1. Using the P lane Sur face Dialog Box....................................................................313 12.15.3. Creating a C ylinder/F rustum .......................................................................................313 12.15.3.1. Using the C ylinder D ialog Box............................................................................316 12.15.3.2. Using the C onstr uct Geometr y Tool....................................................................317 12.15.4. Creating a S wept Sur face............................................................................................318 12.15.4.1. Using the S wept Sur face Dialog Box...................................................................318 12.15.5. Creating a R evolved Sur face........................................................................................319 12.15.5.1. Using the R evolved Sur face Dialog Box...............................................................319 12.15.6. Creating P eriodic B oundar ies......................................................................................320 12.16. Remo ving G aps B etween B oundar y Zones ...........................................................................322 12.17. Using the L oop S elec tion Tool..............................................................................................323 13.Wrapping O bjec ts........................................................................................................................325 13.1. The Wrapping P rocess ..........................................................................................................325 13.1.1. Extract Edge Z ones .......................................................................................................327 13.1.2. Create Intersec tion L oops .............................................................................................329 13.1.2.1. Individually ..........................................................................................................329 13.1.2.2. Collec tively..........................................................................................................329 13.1.3. Setting G eometr y Recovery Options .............................................................................330 13.1.4. Fixing H oles in O bjec ts.................................................................................................331 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. viiiUser's G uide13.1.5. Shrink Wrapping the O bjec ts........................................................................................335 13.1.6. Impr oving the M esh O bjec ts.........................................................................................338 13.1.7. Objec t Wrapping Options .............................................................................................339 13.1.7.1. Resolving Thin R egions D uring O bjec t Wrapping ..................................................339 13.1.7.2. Detecting H oles in the O bjec t..............................................................................340 13.1.7.3. Impr oving F eature Captur e For M esh O bjec ts.......................................................340 14. Creating a M esh ...........................................................................................................................341 14.1. Choosing the M eshing S trategy.............................................................................................341 14.1.1. Boundar y Mesh C ontaining Only Triangular F aces.........................................................342 14.1.2. Mixed B oundar y Mesh ..................................................................................................343 14.1.3. Hexcore Mesh ..............................................................................................................344 14.1.4. CutCell M esh ................................................................................................................345 14.1.5. Additional M eshing Tasks .............................................................................................345 14.1.6. Inser ting I sola ted N odes in to a Tet M esh .......................................................................346 14.2. Using the A uto Mesh D ialog Box............................................................................................349 14.3. Gener ating a Thin Volume M esh ............................................................................................352 14.4. Gener ating P yramids .............................................................................................................352 14.4.1. Creating P yramids ........................................................................................................353 14.4.2. Zones C reated D uring P yramid G ener ation ...................................................................354 14.4.3. Pyramid M eshing P roblems ..........................................................................................355 14.5. Creating a N on-C onformal In terface......................................................................................357 14.5.1. Separ ating the N on-C onformal In terface Between C ell Z ones ........................................357 14.6. Creating a H eat Exchanger Z one ............................................................................................357 14.7. Parallel M eshing ....................................................................................................................359 14.7.1. Auto Partitioning ..........................................................................................................359 14.7.1.1. Availabilit y of G raphic al U ser In terface Options A fter Parallel M eshing ..................360 14.7.1.2. Availabilit y of Text Interface Options A fter Parallel M eshing ..................................362 14.7.2. Computing P artitions ...................................................................................................363 14.7.3. Controlling the Threads ................................................................................................364 15. Gener ating P risms .......................................................................................................................367 15.1. The P rism G ener ation P rocess................................................................................................367 15.1.1. Zones C reated D uring P rism G ener ation .......................................................................369 15.2. Procedur e for C reating Z one-based P risms ............................................................................369 15.3. Prism M eshing Options f or Z one-S pecific P risms ....................................................................373 15.3.1. Growth Options f or Z one-S pecific P risms ......................................................................373 15.3.1.1. Growing P risms S imultaneously fr om M ultiple Z ones ............................................374 15.3.1.2. Growing P risms on a Two-Sided Wall....................................................................376 15.3.1.3. Ignor ing In valid N ormals ......................................................................................377 15.3.1.4. Detecting P roximit y and C ollision ........................................................................378 15.3.1.5. Splitting P rism La yers...........................................................................................380 15.3.1.6. Preser ving Or thogonalit y.....................................................................................381 15.3.2. Offset D istanc es...........................................................................................................381 15.3.3. Direction Vectors..........................................................................................................384 15.3.4. Using A djac ent Zones as the S ides of P risms ..................................................................386 15.3.5. Impr oving P rism M esh Q ualit y......................................................................................389 15.3.5.1. Edge S wapping and S moothing ...........................................................................389 15.3.5.2. Node S moothing .................................................................................................390 15.3.6. Post P rism M esh Q ualit y Impr ovemen t..........................................................................391 15.3.6.1. Impr oving the P rism C ell Q ualit y..........................................................................391 15.3.6.2. Remo ving P oor Q ualit y Cells ................................................................................391 15.3.6.3. Impr oving Warp...................................................................................................392 15.4. Prism M eshing Options f or Sc oped P risms .............................................................................393 ixRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide15.5. Prism M eshing P roblems .......................................................................................................395 16. Gener ating Tetrahedr al M eshes ..................................................................................................399 16.1. Automa tically C reating a Tetrahedr al M esh ............................................................................399 16.1.1. Automa tic M eshing P rocedur e for Tetrahedr al M eshes ..................................................399 16.1.2. Using the A uto M esh Tool.............................................................................................401 16.1.3. Automa tic M eshing of M ultiple C ell Z ones ....................................................................401 16.1.4. Automa tic M eshing f or H ybrid M eshes ..........................................................................402 16.1.5. Further M esh Impr ovemen ts.........................................................................................403 16.2. Manually C reating a Tetrahedr al M esh ...................................................................................403 16.2.1. Manual M eshing P rocedur e for Tetrahedr al M eshes .......................................................403 16.3. Initializing the Tetrahedr al M esh ............................................................................................406 16.3.1. Initializing U sing the Tet D ialog Box..............................................................................406 16.4. Refining the Tetrahedr al M esh ...............................................................................................407 16.4.1. Using L ocal Refinemen t Regions ...................................................................................408 16.4.2. Refinemen t Using the Tet D ialog Box............................................................................409 16.5. Common Tetrahedr al M eshing P roblems ...............................................................................410 17. Gener ating the H excore M esh .....................................................................................................413 17.1. Hexcore Meshing P rocedur e..................................................................................................413 17.2. Using the H excore Dialog Box................................................................................................415 17.3. Controlling H excore Paramet ers............................................................................................416 17.3.1. Maximum or M inimum C ell L ength ...............................................................................416 17.3.2. Buffer La yers................................................................................................................416 17.3.3. Peel La yers...................................................................................................................417 17.3.4. Defining H excore Ex tents.............................................................................................418 17.3.4.1. Hexcore to Selec ted B oundar ies...........................................................................419 17.3.5. Only H excore................................................................................................................420 17.3.6. Local Refinemen t Regions ............................................................................................422 18. Gener ating P olyhedr al M eshes ...................................................................................................423 18.1. Meshing P rocess f or P olyhedr al M eshes .................................................................................423 18.2. Steps f or C reating the P olyhedr al M esh ..................................................................................424 18.2.1. Further M esh Impr ovemen ts.........................................................................................427 18.2.2. Transf erring the P oly M esh t o Solution M ode................................................................427 19. Gener ating P oly-H excore M eshes ...............................................................................................429 19.1. Steps f or C reating the P oly-H excore Mesh ..............................................................................429 20. Gener ating the C utC ell M esh ......................................................................................................433 20.1. The C utCell M eshing P rocess.................................................................................................433 20.2. Using the C utCell D ialog Box.................................................................................................438 20.2.1. Handling Z ero-Thick ness Walls......................................................................................439 20.2.2. Handling O verlapping Sur faces....................................................................................440 20.2.3. Resolving Thin R egions .................................................................................................441 20.3. Impr oving the C utCell M esh ..................................................................................................442 20.4. Post C utCell M esh G ener ation C leanup ..................................................................................443 20.5. Gener ating P risms f or the C utCell M esh .................................................................................443 20.6. The C ut-T et Workflow............................................................................................................448 21. Impr oving the M esh ....................................................................................................................451 21.1. Smoothing N odes .................................................................................................................451 21.1.1. Laplac e Smoothing ......................................................................................................451 21.1.2. Variational S moothing of Tetrahedr al M eshes ................................................................452 21.1.3. Skewness-B ased S moothing of Tetrahedr al M eshes .......................................................452 21.2. Swapping .............................................................................................................................452 21.3. Impr oving the M esh ..............................................................................................................454 21.4. Remo ving S livers fr om a Tetrahedr al M esh .............................................................................454 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. xUser's G uide21.4.1. Automa tic S liver R emo val.............................................................................................454 21.4.2. Remo ving S livers M anually ...........................................................................................455 21.5. Modifying C ells .....................................................................................................................456 21.5.1. Using the M odify C ells D ialog Box.................................................................................456 21.6. Moving N odes ......................................................................................................................458 21.6.1. Automa tic C orrection ...................................................................................................458 21.6.2. Semi-A utoma tic C orrection ..........................................................................................459 21.6.3. Repair ing N egative Volume C ells...................................................................................460 21.7. Cavity Remeshing .................................................................................................................460 21.7.1. Tetrahedr al Cavity Remeshing .......................................................................................461 21.7.2. Hexcore Cavity Remeshing ...........................................................................................463 21.8. Manipula ting C ell Z ones ........................................................................................................466 21.8.1. Active Zones and C ell Types..........................................................................................466 21.8.2. Copying and M oving C ell Z ones ....................................................................................466 21.9. Manipula ting C ell Z one C onditions ........................................................................................467 21.10. Using D omains t o Group and M esh B oundar y Faces.............................................................468 21.10.1. Using D omains ...........................................................................................................468 21.10.2. Defining D omains ......................................................................................................468 21.11. Check ing the M esh .............................................................................................................469 21.12. Selec tively C heck ing the Volume M esh ................................................................................470 21.13. Check ing the M esh Q ualit y..................................................................................................472 21.14. Clearing the M esh ...............................................................................................................473 22. Examining the M esh ....................................................................................................................475 22.1. Displa ying the M esh ..............................................................................................................475 22.1.1. Gener ating the M esh D ispla y using Onscr een Tools.......................................................475 22.1.2. Gener ating the M esh D ispla y Using the D ispla y Grid D ialog Box....................................476 22.1.2.1. Mesh D ispla y Attribut es.......................................................................................477 22.2. Controlling D ispla y Options ...................................................................................................480 22.3. Modifying and S aving the View .............................................................................................482 22.3.1. Mirroring a N on-symmetr ic Domain ..............................................................................482 22.3.2. Controlling P ersp ective and C amer a Paramet ers...........................................................483 22.4. Comp osing a Sc ene ...............................................................................................................484 22.4.1. Changing the D ispla y Properties ...................................................................................484 22.4.2. Transf orming G eometr ic En tities in a Sc ene ...................................................................484 22.4.3. Adding a B ounding F rame ............................................................................................485 22.4.4. Using the Sc ene D escr iption D ialog Box........................................................................485 22.5. Controlling the M ouse B uttons ..............................................................................................487 22.6. Controlling the M ouse P robe Function ..................................................................................488 22.7. Annota ting the D ispla y.........................................................................................................489 22.8. Setting D efault C ontrols........................................................................................................490 23. Determining M esh S tatistics and Q ualit y...................................................................................491 23.1. Determining M esh S tatistics ..................................................................................................491 23.2. Determining M esh Q ualit y....................................................................................................492 23.2.1. Determining Sur face Mesh Q ualit y...............................................................................492 23.2.2. Determining Volume M esh Q ualit y...............................................................................493 23.2.3. Determining B oundar y Cell Q ualit y...............................................................................494 23.2.4. Qualit y Measur e...........................................................................................................494 23.3. Reporting M esh Inf ormation .................................................................................................502 A. Imp orting B oundar y and Volume M eshes ........................................................................................505 A.1. GAMBIT M eshes ......................................................................................................................505 A.2. TetraMesher Volume M esh ......................................................................................................505 A.3. Meshes fr om Third-Party CAD P ackages ..................................................................................505 xiRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uideA.3.1. I-deas U niversal F iles ......................................................................................................506 A.3.1.1. Recogniz ed I-deas D atasets ...................................................................................507 A.3.1.2. Grouping E lemen ts to Create Zones f or a Sur face Mesh ..........................................507 A.3.1.3. Grouping N odes t o Create Zones f or a Volume M esh ..............................................507 A.3.1.4. Periodic B oundar ies..............................................................................................508 A.3.1.5. Deleting D uplic ate Nodes ......................................................................................508 A.3.2. PATRAN N eutr al Files ......................................................................................................508 A.3.2.1. Recogniz ed P ATRAN D atasets ................................................................................508 A.3.2.2. Grouping E lemen ts to Create Zones .......................................................................508 A.3.2.3. Periodic B oundar ies..............................................................................................509 A.3.3. ANSY S Files ....................................................................................................................509 A.3.3.1. Recogniz ed D atasets .............................................................................................509 A.3.3.2. Periodic B oundar ies..............................................................................................509 A.3.4. ARIES F iles .....................................................................................................................509 A.3.5. NASTR AN F iles ...............................................................................................................510 A.3.5.1. Recogniz ed NASTR AN B ulk D ata En tries.................................................................510 A.3.5.2. Periodic B oundar ies..............................................................................................510 A.3.5.3. Deleting D uplic ate Nodes ......................................................................................510 B. Mesh F ile F ormat.............................................................................................................................511 B.1. Guidelines ..............................................................................................................................511 B.2. Formatting C onventions in B inar y Files and F ormatted F iles.....................................................511 B.3. Grid Sections ..........................................................................................................................512 B.3.1. Commen t.......................................................................................................................512 B.3.2. Header ...........................................................................................................................512 B.3.3. Dimensions ....................................................................................................................513 B.3.4. Nodes ............................................................................................................................513 B.3.5. Periodic S hado w Faces...................................................................................................514 B.3.6. Cells ...............................................................................................................................515 B.3.7. Faces..............................................................................................................................516 B.3.8. Edges .............................................................................................................................518 B.3.9. Face Tree........................................................................................................................519 B.3.10. Cell Tree.......................................................................................................................519 B.3.11. Interface Face Parents...................................................................................................520 B.4. Non-G rid Sections ...................................................................................................................521 B.4.1. Zone ..............................................................................................................................521 B.5. Example F iles ..........................................................................................................................522 C. Shortcut Ke ys..................................................................................................................................527 C.1. Shortcut Ke y Actions ...............................................................................................................527 C.1.1. Entity Inf ormation ..........................................................................................................537 Biblio graph y.......................................................................................................................................539 III. Solution M ode....................................................................................................................................541 Using This M anual ..............................................................................................................................dxlv 1.Typographic al Conventions .......................................................................................................dxlv 2. Mathema tical Conventions ......................................................................................................dxlvii 1. Graphic al U ser In terface (GUI) ......................................................................................................549 1.1. GUI C omp onen ts....................................................................................................................549 1.1.1. The R ibbon....................................................................................................................550 1.1.2. The Outline View ............................................................................................................551 1.1.3. Graphics Windo ws..........................................................................................................553 1.1.4. Quick S earch..................................................................................................................556 1.1.5. Toolbars .........................................................................................................................556 1.1.5.1. The S tandar d Toolbar .............................................................................................556 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. xiiUser's G uide1.1.5.2. The G raphics Toolbar .............................................................................................557 1.1.5.2.1. Pointer Tools.................................................................................................557 1.1.5.2.2. View Tools.....................................................................................................558 1.1.5.2.3. Projec tion Tools............................................................................................558 1.1.5.2.4. Mesh D ispla y Configur ation ..........................................................................559 1.1.5.2.5. Additional D ispla y Options ............................................................................559 1.1.6. Task P ages ......................................................................................................................560 1.1.7. The C onsole ...................................................................................................................560 1.1.8. Dialog Boxes..................................................................................................................561 1.1.8.1. Input C ontrols.......................................................................................................564 1.1.8.1.1. Tabs ..............................................................................................................564 1.1.8.1.2. Buttons .........................................................................................................564 1.1.8.1.3. Check B oxes..................................................................................................564 1.1.8.1.4. Radio B uttons ...............................................................................................564 1.1.8.1.5. Text En try Boxes............................................................................................564 1.1.8.1.6. Integer N umb er En try Boxes..........................................................................564 1.1.8.1.7. Real N umb er En try Boxes..............................................................................565 1.1.8.1.8. Filter Text En try Boxes...................................................................................565 1.1.8.1.9. Single-S elec tion Lists ....................................................................................565 1.1.8.1.10. Multiple-S elec tion Lists ...............................................................................566 1.1.8.1.11. Drop-D own Lists .........................................................................................567 1.1.8.1.12. Scales .........................................................................................................567 1.1.8.2. Types of D ialog Boxes............................................................................................568 1.1.8.2.1. Information D ialog Boxes..............................................................................568 1.1.8.2.2. Warning D ialog Boxes...................................................................................568 1.1.8.2.3. Error D ialog Boxes.........................................................................................568 1.1.8.2.4. The Working D ialog Box................................................................................569 1.1.8.2.5. Question D ialog Box.....................................................................................569 1.1.8.2.6. The S elec t File D ialog Box..............................................................................569 1.1.8.2.6.1. The S elec t File D ialog Box (Windo ws)....................................................569 1.1.8.2.6.2. The S elec t File D ialog Box (Linux) ..........................................................570 1.2. Modifying the G raphic al User In terface....................................................................................573 1.3. Setting U ser P references/Options ............................................................................................573 1.4. Fluen t Graphic al User In terface in Japanese .............................................................................575 1.5. Using the H elp S ystem............................................................................................................576 1.5.1. Task P age and D ialog Box Help.......................................................................................576 1.5.2. Context-Sensitiv e Help (Linux Only) ................................................................................576 1.5.3. Obtaining Lic ense U se Inf ormation .................................................................................577 1.5.4. Version and R elease Inf ormation .....................................................................................577 2.Text User In terface (TUI) ................................................................................................................579 3. Reading and Writing F iles .............................................................................................................581 3.1. Shortcuts f or R eading and Writing F iles ...................................................................................581 3.1.1. Default F ile Suffix es........................................................................................................582 3.1.2. Binar y Files .....................................................................................................................583 3.1.3. Detecting F ile F ormat.....................................................................................................583 3.1.4. Recent File List ...............................................................................................................583 3.1.5. Reading and Writing C ompr essed F iles ...........................................................................583 3.1.5.1. Reading C ompr essed F iles .....................................................................................583 3.1.5.2. Writing C ompr essed F iles .......................................................................................584 3.1.6. Tilde Expansion (Linux S ystems Only) ..............................................................................585 3.1.7. Automa tic N umb ering of F iles ........................................................................................585 3.1.8. Disabling the O verwrite Confir mation P rompt ................................................................586 xiiiRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide3.1.9. Toolbar B uttons ..............................................................................................................586 3.2. Reading M esh F iles .................................................................................................................586 3.3. Reading and Writing C ase and D ata Files .................................................................................587 3.3.1. Reading and Writing C ase F iles .......................................................................................588 3.3.2. Reading and Writing D ata Files .......................................................................................589 3.3.3. Reading and Writing C ase and D ata Files Together ..........................................................589 3.3.4. Reading and Writing F iles U sing Hier archic al D ata Format (HDF) ......................................589 3.3.5. Automa tic S aving of C ase and D ata Files .........................................................................591 3.4. Reading F luen t/UNS and R AMP ANT C ase and D ata Files...........................................................593 3.5. Reading and Writing P rofile F iles .............................................................................................594 3.5.1. Reading P rofile F iles .......................................................................................................594 3.5.2. Writing P rofile F iles .........................................................................................................594 3.6. Reading and Writing B oundar y Conditions ..............................................................................596 3.7.Writing a B oundar y Mesh ........................................................................................................597 3.8. Reading Scheme S ource Files ..................................................................................................597 3.9. Creating and R eading J ournal F iles ..........................................................................................597 3.9.1. Procedur e......................................................................................................................599 3.9.2. Multiple J ournal F iles......................................................................................................600 3.10. Creating Transcr ipt F iles ........................................................................................................601 3.11. Imp orting F iles......................................................................................................................601 3.11.1. ABAQUS F iles ...............................................................................................................604 3.11.2. CFX F iles.......................................................................................................................604 3.11.3. Meshes and D ata in C GNS F ormat.................................................................................605 3.11.4. EnS ight Files .................................................................................................................606 3.11.5. ANSY S FIDAP N eutr al Files ............................................................................................606 3.11.6. GAMBIT and G eoM esh M esh F iles .................................................................................607 3.11.7. HYPERMESH ASCII F iles .................................................................................................607 3.11.8. I-deas U niversal F iles.....................................................................................................607 3.11.9. LST C Files .....................................................................................................................607 3.11.10. Marc POST F iles ..........................................................................................................608 3.11.11. Mechanic al APDL F iles ................................................................................................608 3.11.12. NASTR AN F iles ............................................................................................................608 3.11.13. PATRAN N eutr al Files...................................................................................................609 3.11.14. PLOT3D F iles...............................................................................................................609 3.11.15. PTC M echanic a Design F iles ........................................................................................609 3.11.16. Tecplot F iles................................................................................................................610 3.11.17. Fluen t 4 C ase F iles ......................................................................................................610 3.11.18. PreBFC F iles ................................................................................................................610 3.11.19. Partition F iles..............................................................................................................610 3.11.20. CHEMKIN M echanism .................................................................................................611 3.12. Exp orting S olution D ata........................................................................................................611 3.12.1. Exp orting Limita tions ...................................................................................................612 3.13. Exp orting S olution D ata af ter a C alcula tion ............................................................................613 3.13.1. ABAQUS F iles ...............................................................................................................614 3.13.2. Mechanic al APDL Input F iles .........................................................................................614 3.13.3. ASCII F iles.....................................................................................................................615 3.13.4. AVS Files.......................................................................................................................615 3.13.5. CDA T for CFD-P ost and EnS ight.....................................................................................615 3.13.6. CGNS F iles ....................................................................................................................617 3.13.7. Data Explor er Files ........................................................................................................617 3.13.8. EnS ight Case G old F iles.................................................................................................618 3.13.9. FAST F iles .....................................................................................................................621 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. xivUser's G uide3.13.10. FAST S olution F iles......................................................................................................621 3.13.11. FieldV iew U nstr uctured F iles .......................................................................................621 3.13.12. I-deas U niversal F iles...................................................................................................622 3.13.13. NASTR AN F iles ............................................................................................................623 3.13.14. PATRAN F iles...............................................................................................................624 3.13.15. TAITherm Files ............................................................................................................624 3.13.16. Tecplot F iles................................................................................................................625 3.14. Exp orting S teady-State Particle Hist ory Data..........................................................................625 3.15. Exp orting D ata D uring a Transien t Calcula tion .......................................................................627 3.15.1. Creating A utoma tic Exp ort Definitions f or S olution D ata...............................................629 3.15.2. Creating A utoma tic Exp ort Definitions f or Transien t Particle Hist ory Data......................631 3.16. Exp orting t o ANSY S CFD-P ost................................................................................................633 3.17. Parallel Exp orting t o ANSY S EnS ight......................................................................................634 3.18. Managing S olution F iles ........................................................................................................635 3.19. Mesh-t o-M esh S olution In terpolation ....................................................................................637 3.19.1. Performing M esh-t o-M esh S olution In terpolation ..........................................................637 3.19.2. Format of the In terpolation F ile.....................................................................................639 3.20. Mapping D ata for Fluid-S tructure Interaction (FSI) A pplic ations ..............................................640 3.20.1. FEA F ile F ormats...........................................................................................................640 3.20.2. Using the FSI M apping D ialog Boxes.............................................................................641 3.21. Saving P icture Files ...............................................................................................................645 3.21.1. Using the S ave Picture Dialog Box.................................................................................646 3.21.1.1. Choosing the P icture File F ormat..........................................................................647 3.21.1.2. Specifying the C olor M ode...................................................................................649 3.21.1.3. Choosing the F ile Type.........................................................................................649 3.21.1.4. Defining the R esolution .......................................................................................649 3.21.1.5. Picture Options ....................................................................................................650 3.21.2. Picture Options f or P ostScr ipt F iles................................................................................650 3.21.2.1. Windo w D umps (Linux S ystems Only) ...................................................................650 3.21.2.2. Previewing the P icture Image ...............................................................................651 3.22. Setting D ata File Q uantities ...................................................................................................651 3.23. The .fluen t File.......................................................................................................................653 4. Unit S ystems ..................................................................................................................................655 4.1. Restrictions on U nits ...............................................................................................................655 4.2. Units in M esh F iles ..................................................................................................................656 4.3. Built-In U nit S ystems in ANSY S Fluen t......................................................................................656 4.4. Customizing U nits ...................................................................................................................657 4.4.1. Listing C urrent Units .......................................................................................................657 4.4.2. Changing the U nits f or a Q uantity...................................................................................657 4.4.3. Defining a N ew U nit.......................................................................................................657 4.4.3.1. Determining the C onversion F actor........................................................................658 5. Fluen t Expressions L anguage .......................................................................................................659 5.1. Introduction t o Expr essions .....................................................................................................659 5.1.1. Expr ession S yntax..........................................................................................................659 5.1.1.1. Expr ession D ata Types...........................................................................................659 5.1.1.2. Expr ession Values ..................................................................................................659 5.1.1.3. Expr ession Op erations and F unctions .....................................................................660 5.1.2. Units Valida tion ..............................................................................................................662 5.2. Expr ession S ources.................................................................................................................662 5.2.1. Field Variables ................................................................................................................662 5.2.2. Solution Variables ...........................................................................................................662 5.2.3. Scien tific C onstan ts........................................................................................................663 xvRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide5.2.4. Aliases ...........................................................................................................................663 5.3. Creating and U sing Expr essions ...............................................................................................664 5.3.1. Directly A pplied Expr essions ...........................................................................................665 5.3.2. Named Expr essions ........................................................................................................666 5.3.3. Context Specific ation .....................................................................................................669 5.4. Expr ession Examples ...............................................................................................................669 5.4.1. Parabolic Inflo w Profile ...................................................................................................669 5.4.2. Time-V aried P arabolic Inflo w...........................................................................................672 5.4.3. Controlled Outlet Temp erature.......................................................................................675 5.5. Appendix: Supp orted F ield Variables .......................................................................................679 6. Reading and M anipula ting M eshes ..............................................................................................703 6.1. Mesh Topologies .....................................................................................................................703 6.1.1. Examples of A cceptable M esh Topologies .......................................................................704 6.1.2. Face-Node C onnec tivit y in ANSY S Fluen t........................................................................709 6.1.2.1. Face-Node C onnec tivit y for Triangular C ells ............................................................710 6.1.2.2. Face-Node C onnec tivit y for Q uadr ilateral Cells .......................................................711 6.1.2.3. Face-Node C onnec tivit y for Tetrahedr al Cells ..........................................................712 6.1.2.4. Face-Node C onnec tivit y for Wedge C ells.................................................................713 6.1.2.5. Face-Node C onnec tivit y for P yramidal C ells ............................................................714 6.1.2.6. Face-Node C onnec tivit y for H ex Cells .....................................................................715 6.1.2.7. Face-Node C onnec tivit y for P olyhedr al Cells ...........................................................716 6.1.3. Choosing the A ppropriate Mesh Type.............................................................................716 6.1.3.1. Setup Time ............................................................................................................716 6.1.3.2. Computa tional Exp ense .........................................................................................717 6.1.3.3. Numer ical D iffusion ...............................................................................................717 6.2. Mesh R equir emen ts and C onsider ations ..................................................................................718 6.2.1. Geometr y/M esh R equir emen ts.......................................................................................718 6.2.2. Mesh Q ualit y..................................................................................................................719 6.2.2.1. Mesh E lemen t Distribution ....................................................................................721 6.2.2.2. Cell Q ualit y............................................................................................................722 6.2.2.3. Smoothness ..........................................................................................................723 6.2.2.4. Flow-Field D ependenc y.........................................................................................723 6.3. Mesh S ources..........................................................................................................................723 6.3.1. ANSY S Meshing M esh F iles .............................................................................................724 6.3.2. Fluen t Meshing M ode M esh F iles ....................................................................................724 6.3.3. Fluen t Meshing M esh F iles..............................................................................................724 6.3.4. GAMBIT M esh F iles .........................................................................................................724 6.3.5. GeoM esh M esh F iles .......................................................................................................724 6.3.6. PreBFC M esh F iles...........................................................................................................725 6.3.6.1. Structured M esh F iles ............................................................................................725 6.3.6.2. Unstr uctured Triangular and Tetrahedr al M esh F iles................................................725 6.3.7. ICEM CFD M esh F iles ......................................................................................................725 6.3.8. I-deas U niversal F iles ......................................................................................................725 6.3.8.1. Recogniz ed I-deas D atasets ....................................................................................726 6.3.8.2. Grouping N odes t o Create Face Zones ....................................................................726 6.3.8.3. Grouping E lemen ts to Create Cell Z ones .................................................................726 6.3.8.4. Deleting D uplic ate Nodes ......................................................................................727 6.3.9. NASTR AN F iles ...............................................................................................................727 6.3.9.1. Recogniz ed NASTR AN B ulk D ata En tries.................................................................727 6.3.9.2. Deleting D uplic ate Nodes ......................................................................................727 6.3.10. PATRAN N eutr al Files ....................................................................................................728 6.3.10.1. Recogniz ed P ATRAN D atasets ...............................................................................728 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. xviUser's G uide6.3.10.2. Grouping E lemen ts to Create Cell Z ones ...............................................................729 6.3.11. Mechanic al APDL F iles ..................................................................................................729 6.3.11.1. Recogniz ed ANSY S 5.4 and 5.5 D atasets ...............................................................729 6.3.12. CFX F iles.......................................................................................................................730 6.3.13. Using the f e2ram F ilter to Convert Files .........................................................................731 6.3.14. Remo ving Hanging N odes/E dges .................................................................................731 6.3.14.1. Limita tions ..........................................................................................................732 6.3.15. Fluen t/UNS and R AMP ANT C ase F iles ............................................................................732 6.3.16. FLUENT 4 C ase F iles ......................................................................................................732 6.3.17. ANSY S FIDAP N eutr al Files ............................................................................................733 6.3.18. Reading M ultiple M esh/C ase/D ata Files.........................................................................733 6.3.18.1. Reading M ultiple M esh F iles via the S olution M ode of F luen t................................734 6.3.18.2. Reading M ultiple M esh F iles via the M eshing M ode of F luen t................................735 6.3.18.3. Reading M ultiple M esh F iles via tmer ge................................................................736 6.3.19. Reading Sur face Mesh F iles...........................................................................................737 6.4. Reference Frames ....................................................................................................................738 6.4.1. Creating and U sing R eference Frames .............................................................................738 6.5. Non-C onformal M eshes ...........................................................................................................741 6.5.1. Non-C onformal M esh C alcula tions ..................................................................................742 6.5.1.1. The P eriodic B oundar y Condition Option ...............................................................744 6.5.1.2. The P eriodic R epeats Option ..................................................................................745 6.5.1.3. The C oupled Wall Option .......................................................................................747 6.5.1.4. Matching Option ...................................................................................................748 6.5.1.5. The M app ed Option ...............................................................................................749 6.5.1.6. The S tatic Option ...................................................................................................751 6.5.1.7. Interface Zones A utoma tic N aming C onventions ....................................................751 6.5.1.7.1. Default (N o Options Enabled) ........................................................................752 6.5.1.7.2. Periodic B oundar y Condition .........................................................................752 6.5.1.7.3. Periodic R epeats...........................................................................................752 6.5.1.7.4. Coupled Wall.................................................................................................752 6.5.1.7.5. Matching ......................................................................................................753 6.5.1.7.6. Mapp ed........................................................................................................753 6.5.1.7.7. Static............................................................................................................753 6.5.2. Non-C onformal In terface Algor ithm ................................................................................753 6.5.3. Requir emen ts and Limita tions of N on-C onformal M eshes ...............................................754 6.5.4. Using a N on-C onformal M esh in ANSY S Fluen t................................................................756 6.5.4.1. Manually C reating M esh In terfaces.........................................................................762 6.5.4.2. Transf erring M otion A cross a M esh In terface...........................................................765 6.6. Overset M eshes ......................................................................................................................766 6.6.1. Introduction ...................................................................................................................766 6.6.2. Overset Topologies .........................................................................................................768 6.6.3. Overset D omain C onnec tivit y.........................................................................................772 6.6.3.1. Hole C utting ..........................................................................................................772 6.6.3.1.1. Hole C utting C ontrol.....................................................................................773 6.6.3.2. Overlap M inimiza tion ............................................................................................774 6.6.3.3. Donor S earch........................................................................................................776 6.6.4. Diagnosing O verset In terface Issues ................................................................................776 6.6.4.1. Flood Filling F ails D uring H ole C utting ....................................................................777 6.6.4.1.1. Incorrect Seed C ells.......................................................................................777 6.6.4.1.2. Leakage B etween O verlapping B oundar ies....................................................777 6.6.4.2. Donor S earch F ails D ue t o Or phan C ells..................................................................777 6.6.5. Overset M eshing B est P ractices......................................................................................778 xviiRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide6.6.6. Overset M eshing Limita tions and C ompa tibilities ............................................................779 6.6.6.1. Limita tions ............................................................................................................779 6.6.6.2. Compa tibilities ......................................................................................................780 6.6.7. Setting up an O verset In terface......................................................................................782 6.6.8. Postpr ocessing O verset M eshes ......................................................................................783 6.6.8.1. Overset M esh D ispla y............................................................................................784 6.6.8.2. Overset F ield F unctions ..........................................................................................784 6.6.8.3. Overset C ell M arks.................................................................................................787 6.6.8.4. Overset In terface listing .........................................................................................787 6.6.8.5. Overset P ostpr ocessing Limita tions ........................................................................787 6.6.9. Writing and R eading O verset F iles...................................................................................788 6.7. Check ing the M esh .................................................................................................................788 6.7.1. Mesh C heck R eport........................................................................................................789 6.7.2. Repair ing M eshes ...........................................................................................................790 6.8. Reporting M esh S tatistics ........................................................................................................793 6.8.1. Mesh S ize.......................................................................................................................793 6.8.2. Memor y Usage ...............................................................................................................794 6.8.2.1. Linux S ystems ........................................................................................................794 6.8.2.2. Windo ws Systems ..................................................................................................794 6.8.3. Mesh Z one Inf ormation ..................................................................................................795 6.8.4. Partition S tatistics ...........................................................................................................795 6.9. Converting the M esh t o a P olyhedr al M esh ..............................................................................795 6.9.1. Converting the D omain t o a P olyhedr a...........................................................................796 6.9.1.1. Limita tions ............................................................................................................800 6.9.2. Converting S kewed C ells t o Polyhedr a............................................................................800 6.9.2.1. Limita tions ............................................................................................................800 6.9.3. Converting C ells with Hanging N odes / E dges t o Polyhedr a.............................................801 6.9.3.1. Limita tions ............................................................................................................802 6.10. Modifying the M esh ..............................................................................................................802 6.10.1. Merging Z ones .............................................................................................................803 6.10.1.1. When t o Merge Z ones ..........................................................................................803 6.10.1.2. Using the M erge Z ones D ialog Box.......................................................................804 6.10.2. Separ ating Z ones .........................................................................................................804 6.10.2.1. Separ ating F ace Zones .........................................................................................805 6.10.2.1.1. Metho ds for S epar ating F ace Zones .............................................................805 6.10.2.1.2. Inputs f or S epar ating F ace Zones .................................................................805 6.10.2.2. Separ ating C ell Z ones ..........................................................................................807 6.10.2.2.1. Metho ds for S epar ating C ell Z ones ..............................................................807 6.10.2.2.2. Inputs f or S epar ating C ell Z ones ..................................................................807 6.10.3. Fusing F ace Zones ........................................................................................................809 6.10.3.1. Inputs f or Fusing F ace Zones ................................................................................810 6.10.3.1.1. Fusing Z ones on B ranch C uts.......................................................................810 6.10.4. Creating P eriodic Z ones and In terfaces.........................................................................811 6.10.5. Slitting P eriodic Z ones ..................................................................................................812 6.10.6. Slitting F ace Zones .......................................................................................................812 6.10.6.1. Inputs f or S litting F ace Zones ...............................................................................813 6.10.7. Orienting F ace Zones ....................................................................................................814 6.10.8. Extruding F ace Zones ...................................................................................................814 6.10.8.1. Specifying Ex trusion b y Displac emen t Distanc es..................................................814 6.10.8.2. Specifying Ex trusion b y Parametr ic Coordina tes...................................................815 6.10.9. Replacing , Deleting , Deactivating , and A ctivating Z ones ................................................815 6.10.9.1. Replacing Z ones ..................................................................................................815 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. xviiiUser's G uide6.10.9.2. Deleting Z ones ....................................................................................................816 6.10.9.3. Deactivating Z ones ..............................................................................................817 6.10.9.4. Activating Z ones ..................................................................................................818 6.10.10. Copying C ell Z ones .....................................................................................................818 6.10.11. Replacing the M esh ....................................................................................................819 6.10.11.1. Inputs f or R eplacing the M esh ............................................................................820 6.10.11.2. Limita tions ........................................................................................................820 6.10.12. Managing A djac ent Zones ..........................................................................................820 6.10.12.1. Renaming Z ones U sing the A djac ency Dialog Box...............................................821 6.10.13. Reordering the D omain ..............................................................................................822 6.10.14. Scaling the M esh ........................................................................................................822 6.10.14.1. Using the Sc ale M esh D ialog Box........................................................................824 6.10.14.1.1. Changing the U nit of L ength .....................................................................824 6.10.14.1.2. Unscaling the M esh ...................................................................................824 6.10.14.1.3. Changing the P hysical Size of the M esh .....................................................824 6.10.15. Transla ting the M esh ..................................................................................................824 6.10.15.1. Using the Transla te Mesh D ialog Box..................................................................825 6.10.16. Rotating the M esh ......................................................................................................825 6.10.16.1. Using the R otate Mesh D ialog Box......................................................................826 6.10.17. Impr oving the M esh b y Smoothing and S wapping ......................................................827 6.10.17.1. Smoothing ........................................................................................................827 6.10.17.1.1. Qualit y-Based S moothing ..........................................................................827 6.10.17.1.2. Laplacian S moothing ................................................................................828 6.10.17.1.3. Skewness-B ased S moothing ......................................................................830 6.10.17.2. Face Swapping ...................................................................................................831 6.10.17.2.1. Triangular M eshes .....................................................................................831 6.10.17.2.2. Tetrahedr al M eshes ...................................................................................832 6.10.17.3. Combining S kewness-B ased S moothing and F ace Swapping ..............................833 7. Cell Z one and B oundar y Conditions .............................................................................................835 7.1. Overview ................................................................................................................................835 7.1.1. Available C ell Z one and B oundar y Types.........................................................................836 7.1.2. The C ell Z one and B oundar y Conditions Task P ages .........................................................836 7.1.3. Changing C ell and B oundar y Zone Types........................................................................837 7.1.4. Setting C ell Z one and B oundar y Conditions ....................................................................839 7.1.5. Copying C ell Z one and B oundar y Conditions ..................................................................840 7.1.6. Changing C ell or B oundar y Zone N ames .........................................................................841 7.1.7. Defining N on-U niform C ell Z one and B oundar y Conditions .............................................842 7.1.8. Defining and Viewing P aramet ers...................................................................................842 7.1.8.1. Creating a N ew P aramet er.....................................................................................845 7.1.8.2. Working With A dvanced P aramet er Options ...........................................................847 7.1.8.2.1. Defining Scheme P rocedur es With Input P aramet ers......................................847 7.1.8.2.2. Defining UDFs With Input P aramet ers............................................................849 7.1.8.2.3. Using the Text User In terface to Define UDFs and Scheme P rocedur es With Input Paramet ers.................................................................................................................850 7.1.9. Selec ting C ell or B oundar y Zones in the G raphics D ispla y................................................851 7.1.10. Operating and P eriodic C onditions ...............................................................................852 7.1.11. Highligh ting S elec ted B oundar y Zones .........................................................................853 7.1.12. Saving and R eusing C ell Z one and B oundar y Conditions ...............................................853 7.2. Cell Z one C onditions ...............................................................................................................853 7.2.1. Fluid C onditions .............................................................................................................854 7.2.1.1. Inputs f or Fluid Z ones ............................................................................................854 7.2.1.1.1. Defining the F luid M aterial............................................................................855 xixRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide7.2.1.1.2. Defining S ources...........................................................................................855 7.2.1.1.3. Defining F ixed Values ....................................................................................855 7.2.1.1.4. Specifying a Laminar Z one ............................................................................856 7.2.1.1.5. Specifying a R eaction M echanism .................................................................856 7.2.1.1.6. Specifying the R otation A xis..........................................................................856 7.2.1.1.7. Defining Z one M otion ...................................................................................857 7.2.1.1.8. Defining R adia tion P aramet ers......................................................................859 7.2.2. Solid C onditions .............................................................................................................859 7.2.2.1. Inputs f or S olid Z ones ............................................................................................859 7.2.2.1.1. Defining the S olid M aterial............................................................................860 7.2.2.1.2. Defining a H eat Source..................................................................................860 7.2.2.1.3. Defining a F ixed Temp erature........................................................................860 7.2.2.1.4. Specifying the R otation A xis..........................................................................860 7.2.2.1.5. Defining Z one M otion ...................................................................................861 7.2.2.1.6. Defining R adia tion P aramet ers......................................................................864 7.2.3. Porous M edia C onditions ................................................................................................864 7.2.3.1. Limita tions and A ssumptions of the P orous M edia M odel.......................................864 7.2.3.2. Momen tum E qua tions f or P orous M edia ................................................................865 7.2.3.2.1. Darcy’s Law in P orous M edia ..........................................................................866 7.2.3.2.2. Iner tial L osses in P orous M edia ......................................................................866 7.2.3.3. Relative Viscosity in P orous M edia ..........................................................................867 7.2.3.4. Treatmen t of the Ener gy Equa tion in P orous M edia .................................................867 7.2.3.4.1. Equilibr ium Thermal M odel E qua tions ...........................................................867 7.2.3.4.2. Non-E quilibr ium Thermal M odel E qua tions ....................................................868 7.2.3.5. Treatmen t of Turbulenc e in P orous M edia ...............................................................869 7.2.3.6. Effect of P orosity on Transien t Scalar E qua tions ......................................................869 7.2.3.7. Modeling P orous M edia B ased on P hysical Velocity.................................................869 7.2.3.7.1. Single P hase P orous M edia ............................................................................870 7.2.3.7.2. Multiphase P orous M edia ..............................................................................871 7.2.3.7.2.1. The C ontinuit y Equa tion .......................................................................871 7.2.3.7.2.2. The M omen tum E qua tion .....................................................................871 7.2.3.7.2.3. The Ener gy Equa tion .............................................................................872 7.2.3.8. User Inputs f or P orous M edia .................................................................................872 7.2.3.8.1. Defining the P orous Z one ..............................................................................874 7.2.3.8.2. Defining the P orous Velocity Formula tion ......................................................874 7.2.3.8.3. Defining the F luid P assing Through the P orous M edium ................................875 7.2.3.8.4. Enabling R eactions in a P orous Z one .............................................................875 7.2.3.8.5. Including the R elative Velocity Resistanc e Formula tion ..................................875 7.2.3.8.6. Defining the Viscous and Iner tial R esistanc e Coefficien ts................................876 7.2.3.8.7. Deriving P orous M edia Inputs B ased on Sup erficial Velocity, Using a K nown Pressur e Loss ..............................................................................................................879 7.2.3.8.8. Using the E rgun E qua tion t o Derive Porous M edia Inputs f or a P acked B ed.....880 7.2.3.8.9. Using an Empir ical Equa tion t o Derive Porous M edia Inputs f or Turbulen t Flow Through a P erforated P late.........................................................................................880 7.2.3.8.10. Using Tabula ted D ata to Derive Porous M edia Inputs f or Laminar F low Through a Fibrous M at..............................................................................................................881 7.2.3.8.11. Deriving the P orous C oefficien ts Based on Exp erimen tal P ressur e and Velocity Data...........................................................................................................................881 7.2.3.8.12. Using the P ower-La w M odel........................................................................882 7.2.3.8.13. Defining P orosity........................................................................................883 7.2.3.8.14. Specifying the H eat Transf er Settings ...........................................................883 7.2.3.8.14.1. Equilibr ium Thermal M odel.................................................................883 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. xxUser's G uide7.2.3.8.14.2. Non-E quilibr ium Thermal M odel.........................................................884 7.2.3.8.15. Specifying the R elative Viscosity..................................................................886 7.2.3.8.16. Specifying the R elative Permeabilit y............................................................886 7.2.3.8.17. Specifying the C apillar y Pressur e.................................................................890 7.2.3.8.17.1. Brooks-C orey Model...........................................................................891 7.2.3.8.17.2. Van-G enuch ten M odel........................................................................891 7.2.3.8.17.3. Leverett J-F unction .............................................................................891 7.2.3.8.17.4. Skjae veland M odel.............................................................................892 7.2.3.8.17.5. Capillar y Pressur e Data in a Tabular F ormat.........................................893 7.2.3.8.17.5.1. Specifying Variables in a Tabular F ormat.....................................894 7.2.3.8.17.6. Capillar y Pressur e Usage .....................................................................895 7.2.3.8.18. Defining S ources.........................................................................................897 7.2.3.8.19. Defining F ixed Values ..................................................................................897 7.2.3.8.20. Suppr essing the Turbulen t Viscosity in the P orous R egion ............................897 7.2.3.8.21. Specifying the R otation A xis and D efining Z one M otion ...............................898 7.2.3.9. Solution S trategies f or P orous M edia ......................................................................898 7.2.3.10. Postpr ocessing f or P orous M edia ..........................................................................898 7.2.4. 3D F an Z ones .................................................................................................................899 7.2.4.1. Momen tum E qua tions f or 3D F an Z ones .................................................................899 7.2.4.2. User Inputs f or 3D F an Z ones ..................................................................................901 7.2.4.2.1. Defining the G eometr y of a 3D F an Z one .......................................................902 7.2.4.2.2. Defining the P roperties of a 3D F an Z one .......................................................903 7.2.4.3. 3D F an Z one Limita tions ........................................................................................904 7.2.5. Fixing the Values of Variables ..........................................................................................904 7.2.5.1. Overview of F ixing the Value of a Variable ...............................................................904 7.2.5.1.1. Variables That Can B e Fixed...........................................................................905 7.2.5.2. Procedur e for Fixing Values of Variables in a Z one ...................................................906 7.2.5.2.1. Fixing Velocity Comp onen ts..........................................................................906 7.2.5.2.2. Fixing Temp erature and En thalp y..................................................................907 7.2.5.2.3. Fixing S pecies M ass F ractions ........................................................................907 7.2.5.2.4. Fixing Turbulenc e Quantities .........................................................................907 7.2.5.2.5. Fixing U ser-D efined Sc alars ...........................................................................908 7.2.6. Locking the Temp erature for S olid and S hell Z ones .........................................................908 7.2.7. Defining M ass, Momen tum, Ener gy, and O ther S ources....................................................908 7.2.7.1. Sign C onventions and U nits ...................................................................................909 7.2.7.2. Procedur e for D efining S ources..............................................................................909 7.2.7.2.1. Mass S ources................................................................................................910 7.2.7.2.2. Momen tum S ources......................................................................................910 7.2.7.2.3. Ener gy Sources.............................................................................................910 7.2.7.2.4. Turbulenc e Sources.......................................................................................911 7.2.7.2.4.1. Turbulenc e Sources for the k- ε Model...................................................911 7.2.7.2.4.2. Turbulenc e Sources for the S palar t-Allmar as M odel...............................911 7.2.7.2.4.3. Turbulenc e Sources for the k- ω Model..................................................911 7.2.7.2.4.4. Turbulenc e Sources for the R eynolds S tress M odel................................911 7.2.7.2.5. Mean M ixture Fraction and Varianc e Sources.................................................911 7.2.7.2.6. P-1 R adia tion S ources....................................................................................912 7.2.7.2.7. Progress Variable S ources..............................................................................912 7.2.7.2.8. NO, HCN, and NH3 S ources for the NO x Model...............................................912 7.2.7.2.9. User-D efined Sc alar (UDS) S ources................................................................912 7.3. Boundar y Conditions ..............................................................................................................912 7.3.1. Flow Inlet and Exit B oundar y Conditions .........................................................................913 7.3.2. Using F low Boundar y Conditions ....................................................................................913 xxiRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide7.3.2.1. Determining Turbulenc e Paramet ers......................................................................914 7.3.2.1.1. Specific ation of Turbulenc e Quantities U sing P rofiles .....................................915 7.3.2.1.2. Uniform Specific ation of Turbulenc e Quantities .............................................915 7.3.2.1.3. Turbulenc e Intensit y......................................................................................916 7.3.2.1.4. Turbulenc e Length Sc ale and H ydraulic D iamet er..........................................916 7.3.2.1.5. Turbulen t Viscosity Ratio...............................................................................917 7.3.2.1.6. Relationships f or D eriving Turbulenc e Quantities ...........................................917 7.3.2.1.7. Estima ting M odified Turbulen t Viscosity from Turbulenc e Intensit y and L ength Scale..........................................................................................................................917 7.3.2.1.8. Estima ting Turbulen t Kinetic Ener gy from Turbulenc e Intensit y......................918 7.3.2.1.9. Estima ting Turbulen t Dissipa tion R ate from a L ength Sc ale............................918 7.3.2.1.10. Estima ting Turbulen t Dissipa tion R ate from Turbulen t Viscosity Ratio...........918 7.3.2.1.11. Estima ting Turbulen t Dissipa tion R ate for D ecaying Turbulenc e....................918 7.3.2.1.12. Estima ting S pecific D issipa tion R ate from a L ength Sc ale.............................919 7.3.2.1.13. Estima ting S pecific D issipa tion R ate from Turbulen t Viscosity Ratio..............919 7.3.2.1.14. Estima ting R eynolds S tress C omp onen ts from Turbulen t Kinetic Ener gy.......919 7.3.2.1.15. Specifying Inlet Turbulenc e for LES ..............................................................919 7.3.3. Pressur e Inlet B oundar y Conditions ................................................................................920 7.3.3.1. Inputs a t Pressur e Inlet B oundar ies.........................................................................920 7.3.3.1.1. Summar y......................................................................................................920 7.3.3.1.1.1. Pressur e Inputs and H ydrosta tic H ead ...................................................921 7.3.3.1.1.2. Defining Total P ressur e and Temp erature..............................................922 7.3.3.1.1.3. Defining the F low D irection ..................................................................923 7.3.3.1.1.4. Defining S tatic P ressur e........................................................................926 7.3.3.1.1.5. Prevent Reverse F low............................................................................926 7.3.3.1.1.6. Defining Turbulenc e Paramet ers...........................................................926 7.3.3.1.1.7. Defining R adia tion P aramet ers.............................................................926 7.3.3.1.1.8. Defining S pecies M ass or M ole F ractions ...............................................926 7.3.3.1.1.9. Defining N on-P remix ed C ombustion P aramet ers..................................927 7.3.3.1.1.10. Defining P remix ed C ombustion B oundar y Conditions .........................927 7.3.3.1.1.11. Defining D iscrete Phase B oundar y Conditions .....................................927 7.3.3.1.1.12. Defining M ultiphase B oundar y Conditions ..........................................927 7.3.3.1.1.13. Defining Op en C hannel B oundar y Conditions .....................................927 7.3.3.2. Default S ettings a t Pressur e Inlet B oundar ies..........................................................927 7.3.3.3. Calcula tion P rocedur e at Pressur e Inlet B oundar ies.................................................927 7.3.3.3.1. Incompr essible F low Calcula tions a t Pressur e Inlet B oundar ies.......................928 7.3.3.3.2. Compr essible F low Calcula tions a t Pressur e Inlet B oundar ies.........................928 7.3.4. Velocity Inlet B oundar y Conditions .................................................................................929 7.3.4.1. Inputs a t Velocity Inlet B oundar ies.........................................................................929 7.3.4.1.1. Summar y......................................................................................................929 7.3.4.1.2. Defining the Velocity.....................................................................................930 7.3.4.1.3. Setting the Velocity Magnitude and D irection ................................................931 7.3.4.1.4. Setting the Velocity Magnitude N ormal t o the B oundar y................................931 7.3.4.1.5. Setting the Velocity Comp onen ts..................................................................931 7.3.4.1.6. Setting the A ngular Velocity..........................................................................932 7.3.4.1.7. Defining S tatic P ressur e.................................................................................932 7.3.4.1.8. Defining the Temp erature.............................................................................932 7.3.4.1.9. Defining Outflo w G auge P ressur e..................................................................932 7.3.4.1.10. Defining Turbulenc e Paramet ers..................................................................933 7.3.4.1.11. Defining R adia tion P aramet ers....................................................................933 7.3.4.1.12. Defining S pecies M ass or M ole F ractions ......................................................933 7.3.4.1.13. Defining N on-P remix ed C ombustion P aramet ers.........................................933 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. xxiiUser's G uide7.3.4.1.14. Defining P remix ed C ombustion B oundar y Conditions ..................................933 7.3.4.1.15. Defining D iscrete Phase B oundar y Conditions .............................................933 7.3.4.1.16. Defining M ultiphase B oundar y Conditions ...................................................933 7.3.4.2. Default S ettings a t Velocity Inlet B oundar ies...........................................................933 7.3.4.3. Calcula tion P rocedur e at Velocity Inlet B oundar ies..................................................934 7.3.4.3.1. Treatmen t of Velocity Inlet C onditions a t Flow Inlets .......................................934 7.3.4.3.2. Treatmen t of Velocity Inlet C onditions a t Flow Exits ........................................934 7.3.4.3.3. Densit y Calcula tion .......................................................................................935 7.3.5. Mass-F low Inlet B oundar y Conditions .............................................................................935 7.3.5.1. Limita tions and S pecial C onsider ations ..................................................................935 7.3.5.2. Inputs a t Mass-F low Inlet B oundar ies.....................................................................935 7.3.5.2.1. Summar y......................................................................................................935 7.3.5.2.2. Selec ting the R eference Frame ......................................................................937 7.3.5.2.3. Defining the M ass F low Rate or M ass F lux......................................................937 7.3.5.2.4. More About M ass F lux and A verage M ass F lux...............................................938 7.3.5.2.5. Defining the Total Temp erature.....................................................................938 7.3.5.2.6. Defining S tatic P ressur e.................................................................................939 7.3.5.2.7. Defining the F low D irection ...........................................................................939 7.3.5.2.8. Defining Turbulenc e Paramet ers....................................................................940 7.3.5.2.9. Defining R adia tion P aramet ers......................................................................940 7.3.5.2.10. Defining S pecies M ass or M ole F ractions ......................................................940 7.3.5.2.11. Defining N on-P remix ed C ombustion P aramet ers.........................................940 7.3.5.2.12. Defining P remix ed C ombustion B oundar y Conditions ..................................940 7.3.5.2.13. Defining D iscrete Phase B oundar y Conditions .............................................941 7.3.5.2.14. Defining Op en C hannel B oundar y Conditions ..............................................941 7.3.5.3. Default S ettings a t Mass-F low Inlet B oundar ies.......................................................941 7.3.5.4. Calcula tion P rocedur e at Mass-F low Inlet B oundar ies.............................................941 7.3.5.4.1. Flow Calcula tions a t Mass F low Boundar ies f or Ideal G ases .............................942 7.3.5.4.2. Flow Calcula tions a t Mass F low Boundar ies f or Inc ompr essible F lows.............942 7.3.5.4.3. Flux C alcula tions a t Mass F low Boundar ies.....................................................942 7.3.6. Mass-F low Outlet B oundar y Conditions ..........................................................................942 7.3.6.1. Limita tions ............................................................................................................942 7.3.6.2. Inputs a t Mass-F low Outlet B oundar ies...................................................................943 7.3.6.2.1. Summar y......................................................................................................943 7.3.6.2.2. Selec ting the R eference Frame ......................................................................943 7.3.6.2.3. Defining the M ass F low Rate or M ass F lux......................................................943 7.3.6.2.4. Defining R adia tion P aramet ers......................................................................945 7.3.6.2.5. Defining D iscrete Phase B oundar y Conditions ...............................................945 7.3.6.3. Default S ettings a t Mass-F low Outlet B oundar ies....................................................945 7.3.6.4. Calcula tion P rocedur e at Mass-F low Outlet B oundar ies...........................................945 7.3.6.4.1. Exit C orrected M ass F low Rate.......................................................................946 7.3.7. Inlet Vent Boundar y Conditions ......................................................................................946 7.3.7.1. Inputs a t Inlet Vent Boundar ies...............................................................................947 7.3.7.1.1. Specifying the L oss C oefficien t......................................................................948 7.3.8. Intake Fan B oundar y Conditions .....................................................................................949 7.3.8.1. Inputs a t Intake Fan B oundar ies.............................................................................949 7.3.8.1.1. Specifying the P ressur e Jump ........................................................................950 7.3.9. Pressur e Outlet B oundar y Conditions .............................................................................950 7.3.9.1. Inputs a t Pressur e Outlet B oundar ies......................................................................951 7.3.9.1.1. Summar y......................................................................................................951 7.3.9.1.2. Defining S tatic P ressur e.................................................................................952 7.3.9.1.3. Defining B ackflo w Conditions .......................................................................953 xxiiiRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide7.3.9.1.3.1. Prevent Reverse F low............................................................................955 7.3.9.1.4. Defining R adia tion P aramet ers......................................................................955 7.3.9.1.5. Defining D iscrete Phase B oundar y Conditions ...............................................955 7.3.9.1.6. Defining Op en C hannel B oundar y Conditions ................................................955 7.3.9.2. Default S ettings a t Pressur e Outlet B oundar ies.......................................................955 7.3.9.3. Calcula tion P rocedur e at Pressur e Outlet B oundar ies..............................................955 7.3.9.3.1. Average P ressur e Specific ation ......................................................................956 7.3.9.3.1.1. Strong A veraging .................................................................................956 7.3.9.3.1.2. Weak A veraging ...................................................................................957 7.3.9.4. Other Optional Inputs a t Pressur e Outlet B oundar ies..............................................957 7.3.9.4.1. Non-R eflec ting B oundar y Conditions Option .................................................957 7.3.9.4.2. Target M ass F low Rate Option ........................................................................958 7.3.10. Pressur e Far-Field B oundar y Conditions ........................................................................960 7.3.10.1. Limita tions ..........................................................................................................960 7.3.10.2. Inputs a t Pressur e Far-Field B oundar ies................................................................960 7.3.10.2.1. Summar y....................................................................................................960 7.3.10.2.2. Defining S tatic P ressur e, Mach N umb er, and S tatic Temp erature...................961 7.3.10.2.3. Defining the F low D irection .........................................................................961 7.3.10.2.4. Defining Turbulenc e Paramet ers..................................................................962 7.3.10.2.5. Defining R adia tion P aramet ers....................................................................962 7.3.10.2.6. Defining S pecies Transp ort Paramet ers........................................................962 7.3.10.3. Defining D iscrete Phase B oundar y Conditions ......................................................962 7.3.10.4. Default S ettings a t Pressur e Far-Field B oundar ies..................................................962 7.3.10.5. Calcula tion P rocedur e at Pressur e Far-Field B oundar ies.........................................963 7.3.11. Outflo w Boundar y Conditions .......................................................................................963 7.3.11.1. ANSY S Fluen t’s Treatmen t at Outflo w Boundar ies.................................................964 7.3.11.2. Using Outflo w Boundar ies...................................................................................964 7.3.11.3. Mass F low Split B oundar y Conditions ...................................................................966 7.3.11.4. Other Inputs a t Outflo w Boundar ies.....................................................................966 7.3.11.4.1. Radia tion Inputs a t Outflo w Boundar ies.......................................................966 7.3.11.4.2. Defining D iscrete Phase B oundar y Conditions .............................................967 7.3.12. Outlet Vent Boundar y Conditions ..................................................................................967 7.3.12.1. Inputs a t Outlet Vent Boundar ies..........................................................................967 7.3.12.1.1. Specifying the L oss C oefficien t....................................................................968 7.3.13. Exhaust F an B oundar y Conditions .................................................................................969 7.3.13.1. Inputs a t Exhaust F an B oundar ies.........................................................................969 7.3.13.1.1. Specifying the P ressur e Jump ......................................................................970 7.3.14. Degassing B oundar y Conditions ...................................................................................970 7.3.14.1. Limita tions ..........................................................................................................971 7.3.14.2. Inputs a t Degassing B oundar ies...........................................................................971 7.3.15. Wall B oundar y Conditions .............................................................................................971 7.3.15.1. Inputs a t Wall B oundar ies.....................................................................................971 7.3.15.1.1. Summar y....................................................................................................971 7.3.15.2. Wall M otion .........................................................................................................972 7.3.15.2.1. Defining a S tationar y Wall...........................................................................973 7.3.15.2.2. Velocity Conditions f or M oving Walls ...........................................................973 7.3.15.2.3. Shear C onditions a t Walls ............................................................................975 7.3.15.2.4. No-Slip Walls ...............................................................................................975 7.3.15.2.5. Specified S hear ...........................................................................................975 7.3.15.2.6. Specular ity Coefficien t................................................................................976 7.3.15.2.7. Marangoni S tress........................................................................................977 7.3.15.2.8. Wall R oughness E ffects in Turbulen t Wall-B ounded F lows.............................978 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. xxivUser's G uide7.3.15.2.8.1. Standar d La w-of-the-W all M odified f or R oughness ..............................978 7.3.15.2.8.1.1. Setting the R oughness P aramet ers.............................................982 7.3.15.2.8.2. Additional R oughness M odels f or Icing S imula tions .............................982 7.3.15.2.8.2.1. Specified R oughness ..................................................................983 7.3.15.2.8.2.2. NASA C orrelation .......................................................................984 7.3.15.2.8.2.3. Shin-et-al ...................................................................................984 7.3.15.2.8.2.4. ICE3D R oughness F ile.................................................................984 7.3.15.3. Thermal B oundar y Conditions a t Walls..................................................................984 7.3.15.3.1. Heat Flux B oundar y Conditions ...................................................................986 7.3.15.3.2. Temp erature Boundar y Conditions ..............................................................986 7.3.15.3.3. Convective Heat Transf er B oundar y Conditions ............................................986 7.3.15.3.4. External R adia tion B oundar y Conditions ......................................................986 7.3.15.3.5. Combined C onvection and Ex ternal R adia tion B oundar y Conditions ............986 7.3.15.3.6. Augmen ted H eat Transf er............................................................................986 7.3.15.3.7. Thin-W all Thermal R esistanc e Paramet ers.....................................................986 7.3.15.3.8. Thermal C onditions f or Two-Sided Walls.......................................................988 7.3.15.3.9. Shell C onduc tion .........................................................................................989 7.3.15.3.10. Heat Transf er B oundar y Conditions Through S ystem C oupling ...................990 7.3.15.3.11. Heat Transf er Boundar y Conditions A cross a M app ed In terface...................991 7.3.15.4. Species B oundar y Conditions f or Walls.................................................................992 7.3.15.4.1. Reaction B oundar y Conditions f or Walls.......................................................993 7.3.15.5. Radia tion B oundar y Conditions f or Walls..............................................................993 7.3.15.6. Discrete Phase M odel (DPM) B oundar y Conditions f or Walls..................................994 7.3.15.6.1. Wall A dhesion C ontact Angle f or VOF M odel................................................994 7.3.15.7. User-D efined Sc alar (UDS) B oundar y Conditions f or Walls.....................................994 7.3.15.8. Wall F ilm C onditions f or Walls...............................................................................994 7.3.15.9. Structural M odel C onditions f or Walls...................................................................994 7.3.15.10. Default S ettings a t Wall B oundar ies....................................................................994 7.3.15.11. Shear-S tress C alcula tion P rocedur e at Wall B oundar ies........................................994 7.3.15.11.1. Shear-S tress C alcula tion in Laminar F low...................................................995 7.3.15.11.2. Shear-S tress C alcula tion in Turbulen t Flows................................................995 7.3.15.12. Heat Transf er C alcula tions a t Wall B oundar ies.....................................................995 7.3.15.12.1. Temp erature Boundar y Conditions ............................................................995 7.3.15.12.2. Heat Flux B oundar y Conditions .................................................................996 7.3.15.12.3. Convective Heat Transf er B oundar y Conditions ..........................................996 7.3.15.12.4. External R adia tion B oundar y Conditions ....................................................996 7.3.15.12.5. Combined Ex ternal C onvection and R adia tion B oundar y Conditions ..........997 7.3.15.12.6. Calcula tion of the F luid-S ide H eat Transf er C oefficien t................................997 7.3.16. Symmetr y Boundar y Conditions ...................................................................................997 7.3.16.1. Examples of S ymmetr y Boundar ies......................................................................997 7.3.16.2. Calcula tion P rocedur e at Symmetr y Boundar ies....................................................999 7.3.17. Periodic B oundar y Conditions .......................................................................................999 7.3.17.1. Examples of P eriodic B oundar ies........................................................................1000 7.3.17.2. Inputs f or P eriodic B oundar ies............................................................................1000 7.3.17.3. Default S ettings a t Periodic B oundar ies..............................................................1002 7.3.17.4. Calcula tion P rocedur e at Periodic B oundar ies.....................................................1002 7.3.18. Axis B oundar y Conditions ...........................................................................................1002 7.3.18.1. Calcula tion P rocedur e at Axis B oundar ies...........................................................1002 7.3.19. Fan B oundar y Conditions ............................................................................................1002 7.3.19.1. Fan E qua tions ....................................................................................................1003 7.3.19.1.1. Modeling the P ressur e Rise A cross the F an.................................................1003 7.3.19.1.2. Modeling the F an S wirl Velocity.................................................................1003 xxvRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide7.3.19.2. User Inputs f or Fans ............................................................................................1004 7.3.19.2.1. Iden tifying the F an Z one ............................................................................1004 7.3.19.2.2. Defining the P ressur e Jump .......................................................................1005 7.3.19.2.2.1. Polynomial, Piecewise-Linear , or P iecewise-P olynomial F unction ........1005 7.3.19.2.2.2. Constan t Value .................................................................................1006 7.3.19.2.2.3. User-D efined F unction or P rofile .......................................................1006 7.3.19.2.2.4. Example: Determining the P ressur e Jump F unction ...........................1006 7.3.19.2.3. Defining D iscrete Phase B oundar y Conditions f or the F an..........................1007 7.3.19.2.4. Defining the F an S wirl Velocity...................................................................1007 7.3.19.2.4.1. Polynomial F unction .........................................................................1008 7.3.19.2.4.2. Constan t Value .................................................................................1008 7.3.19.2.4.3. User-D efined F unction or P rofile .......................................................1008 7.3.19.3. Postpr ocessing f or Fans ......................................................................................1009 7.3.19.3.1. Reporting the P ressur e Rise Through the F an.............................................1009 7.3.19.3.2. Graphic al Plots ..........................................................................................1009 7.3.20. Radia tor B oundar y Conditions ....................................................................................1009 7.3.20.1. Radia tor Equa tions .............................................................................................1009 7.3.20.1.1. Modeling the P ressur e Loss Through a R adia tor.........................................1009 7.3.20.1.2. Modeling the H eat Transf er Through a R adia tor..........................................1010 7.3.20.1.2.1. Calcula ting the H eat Transf er C oefficien t...........................................1010 7.3.20.2. User Inputs f or R adia tors....................................................................................1011 7.3.20.2.1. Iden tifying the R adia tor Z one ....................................................................1012 7.3.20.2.2. Defining the P ressur e Loss C oefficien t Function .........................................1012 7.3.20.2.2.1. Polynomial, Piecewise-Linear , or P iecewise-P olynomial F unction ........1012 7.3.20.2.2.2. Constan t Value .................................................................................1013 7.3.20.2.2.3. Example: Calcula ting the L oss C oefficien t..........................................1013 7.3.20.2.3. Defining the H eat Flux P aramet ers.............................................................1014 7.3.20.2.3.1. Polynomial, Piecewise-Linear , or P iecewise-P olynomial F unction ........1014 7.3.20.2.3.2. Constan t Value .................................................................................1015 7.3.20.2.3.3. Example: Determining the H eat Transf er C oefficien t Function ............1015 7.3.20.2.4. Defining D iscrete Phase B oundar y Conditions f or the R adia tor...................1015 7.3.20.3. Postpr ocessing f or R adia tors..............................................................................1015 7.3.20.3.1. Reporting the R adia tor P ressur e Drop........................................................1015 7.3.20.3.2. Reporting H eat Transf er in the R adia tor......................................................1016 7.3.20.3.3. Graphic al Plots ..........................................................................................1016 7.3.21. Porous J ump B oundar y Conditions .............................................................................1016 7.3.21.1. User Inputs f or the P orous J ump M odel..............................................................1017 7.3.21.1.1. Iden tifying the P orous J ump Z one .............................................................1018 7.3.21.1.2. Defining D iscrete Phase B oundar y Conditions f or the P orous J ump ............1018 7.3.21.2. Postpr ocessing f or the P orous J ump ...................................................................1018 7.4. Editing M ultiple B oundar y Conditions a t Onc e.......................................................................1018 7.5. Boundar y Acoustic Wave Models ...........................................................................................1021 7.5.1. Turbo-Specific N on-R eflec ting B oundar y Conditions .....................................................1021 7.5.1.1. Overview .............................................................................................................1021 7.5.1.2. Limita tions ..........................................................................................................1022 7.5.1.3. Theor y.................................................................................................................1024 7.5.1.3.1. Equa tions in C haracteristic Variable F orm.....................................................1024 7.5.1.3.2. Inlet B oundar y............................................................................................1026 7.5.1.3.3. Outlet B oundar y.........................................................................................1028 7.5.1.3.4. Updated F low Variables ...............................................................................1029 7.5.1.4. Using Turbo-Specific N on-R eflec ting B oundar y Conditions ...................................1029 7.5.1.4.1. Using the NRBCs with the M ixing-P lane M odel.............................................1030 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. xxviUser's G uide7.5.1.4.2. Using the NRBCs in P arallel ANSY S Fluen t.....................................................1031 7.5.2. Gener al N on-R eflec ting B oundar y Conditions ...............................................................1031 7.5.2.1. Overview .............................................................................................................1031 7.5.2.2. Restrictions and Limita tions .................................................................................1031 7.5.2.3. Theor y.................................................................................................................1032 7.5.2.4. Using the G ener al Non-R eflec ting B oundar y Condition .........................................1036 7.5.3. Imp edanc e Boundar y Conditions ..................................................................................1037 7.5.3.1. Restrictions and Limita tions .................................................................................1038 7.5.3.2. Theor y.................................................................................................................1038 7.5.3.3. Using the Imp edanc e Boundar y Condition ...........................................................1039 7.5.4. Transpar ent Flow Forcing B oundar y Conditions .............................................................1041 7.5.4.1. Restrictions and Limita tions .................................................................................1041 7.5.4.2. Theor y.................................................................................................................1041 7.5.4.3. Using the Transpar ent Flow Forcing B oundar y Condition ......................................1042 7.6. User-D efined F an M odel........................................................................................................1043 7.6.1. Steps f or U sing the U ser-D efined F an M odel..................................................................1044 7.6.2. Example of a U ser-D efined F an.....................................................................................1044 7.6.2.1. Setting the U ser-D efined F an P aramet ers.............................................................1045 7.6.2.2. Sample U ser-D efined F an P rogram.......................................................................1046 7.6.2.3. Initializing the F low Field and P rofile F iles.............................................................1048 7.6.2.4. Selec ting the P rofiles ...........................................................................................1048 7.6.2.5. Performing the C alcula tion ..................................................................................1049 7.6.2.6. Results .................................................................................................................1050 7.7. Profiles .................................................................................................................................1051 7.7.1. Profile S pecific ation Types............................................................................................1051 7.7.2. Profile F ile F ormats.......................................................................................................1052 7.7.2.1. Standar d Profiles ..................................................................................................1052 7.7.2.1.1. Example ......................................................................................................1053 7.7.2.2. CSV P rofiles .........................................................................................................1054 7.7.3. Using P rofiles ...............................................................................................................1056 7.7.3.1. Check ing and D eleting P rofiles ............................................................................1057 7.7.3.2. Viewing P rofile D ata.............................................................................................1058 7.7.3.3. Example ..............................................................................................................1059 7.7.4. Reorienting P rofiles ......................................................................................................1059 7.7.4.1. Steps f or C hanging the P rofile Or ientation ............................................................1060 7.7.4.2. Profile Or ienting Example ....................................................................................1062 7.7.5. Replic ating P rofiles .......................................................................................................1064 7.7.5.1. Steps f or R eplic ating a P rofile ...............................................................................1064 7.7.6. Defining Transien t Cell Z one and B oundar y Conditions .................................................1066 7.7.6.1. Standar d Transien t Profiles ...................................................................................1067 7.7.6.2. Tabular Transien t Profiles ......................................................................................1068 7.7.6.3. Profiles f or M oving and D eforming M eshes ..........................................................1069 7.8. Coupling B oundar y Conditions with GT-PO WER ....................................................................1070 7.8.1. Requir emen ts and R estrictions .....................................................................................1070 7.8.2. User Inputs ...................................................................................................................1071 7.8.3. Torque-S peed C oupling with GT-PO WER .......................................................................1074 7.9. Coupling B oundar y Conditions with WAVE.............................................................................1075 7.9.1. Requir emen ts and R estrictions .....................................................................................1075 7.9.2. User Inputs ...................................................................................................................1076 8. Physical P roperties ......................................................................................................................1079 8.1. Defining M aterials.................................................................................................................1079 8.1.1. Physical Properties f or S olid M aterials...........................................................................1080 xxviiRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide8.1.2. Material Types and D atabases .......................................................................................1080 8.1.3. Using the Create/Edit M aterials Dialog Box.................................................................1081 8.1.3.1. Modifying P roperties of an Existing M aterial.........................................................1083 8.1.3.2. Renaming an Existing M aterial.............................................................................1084 8.1.3.3. Copying M aterials fr om the ANSY S Fluen t Database .............................................1084 8.1.3.4. Creating a N ew M aterial.......................................................................................1086 8.1.3.5. Saving M aterials and P roperties ...........................................................................1086 8.1.3.6. Deleting a M aterial..............................................................................................1087 8.1.3.7. Changing the Or der of the M aterials List ...............................................................1087 8.1.4. Using a U ser-D efined M aterials D atabase ......................................................................1087 8.1.4.1. Opening a U ser-D efined D atabase .......................................................................1088 8.1.4.2. Viewing M aterials in a U ser-D efined D atabase ......................................................1089 8.1.4.3. Copying M aterials fr om a U ser-D efined D atabase .................................................1089 8.1.4.4. Copying M aterials fr om the C ase t o a U ser-D efined D atabase ...............................1090 8.1.4.5. Modifying P roperties of an Existing M aterial.........................................................1091 8.1.4.6. Creating a N ew M aterials D atabase and M aterials.................................................1092 8.1.4.7. Deleting M aterials fr om a D atabase ......................................................................1094 8.2. Defining P roperties U sing Temp erature-Dependen t Functions ...............................................1095 8.2.1. Inputs f or P olynomial F unctions ....................................................................................1095 8.2.2. Inputs f or P iecewise-Linear F unctions ...........................................................................1096 8.2.3. Inputs f or P iecewise-P olynomial F unctions ....................................................................1098 8.2.4. Check ing and M odifying Existing P rofiles ......................................................................1099 8.3. Densit y.................................................................................................................................1099 8.3.1. Defining D ensit y for Various F low Regimes ....................................................................1099 8.3.1.1. Mixing D ensit y Relationships in M ultiple-Z one M odels .........................................1100 8.3.2. Input of C onstan t Densit y.............................................................................................1100 8.3.3. Inputs f or the B oussinesq A pproxima tion ......................................................................1100 8.3.4. Compr essible Liquid D ensit y Metho d............................................................................1100 8.3.4.1. Compr essible Liquid Inputs ..................................................................................1102 8.3.4.2. Compr essible Liquid D ensit y Metho d Availabilit y.................................................1104 8.3.5. Densit y as a P rofile F unction of Temp erature.................................................................1104 8.3.6. Incompr essible Ideal G as La w.......................................................................................1104 8.3.6.1. Densit y Inputs f or the Inc ompr essible Ideal G as La w.............................................1104 8.3.7. Ideal G as La w for C ompr essible F lows...........................................................................1105 8.3.7.1. Densit y Inputs f or the Ideal G as La w for C ompr essible F lows.................................1105 8.3.8. Comp osition-D ependen t Densit y for M ultic omp onen t Mixtures....................................1106 8.4. Viscosity...............................................................................................................................1107 8.4.1. Input of C onstan t Viscosity...........................................................................................1108 8.4.2. Viscosity as a F unction of Temp erature..........................................................................1108 8.4.2.1. Suther land Viscosity La w......................................................................................1109 8.4.2.1.1. Inputs f or Suther land ’s La w.........................................................................1109 8.4.2.2. Power-La w Viscosity La w......................................................................................1110 8.4.2.2.1. Inputs f or the P ower La w.............................................................................1110 8.4.3. Defining the Viscosity Using K inetic Theor y...................................................................1111 8.4.4. Comp osition-D ependen t Viscosity for M ultic omp onen t Mixtures..................................1111 8.4.5. Viscosity for N on-N ewtonian F luids ...............................................................................1112 8.4.5.1. Temp erature Dependen t Viscosity........................................................................1113 8.4.5.2. Power La w for N on-N ewtonian Viscosity...............................................................1113 8.4.5.2.1. Inputs f or the N on-N ewtonian P ower La w....................................................1114 8.4.5.3. The C arreau M odel f or P seudo-P lastics .................................................................1114 8.4.5.3.1. Inputs f or the C arreau M odel.......................................................................1114 8.4.5.4. Cross M odel.........................................................................................................1115 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. xxviiiUser's G uide8.4.5.4.1. Inputs f or the C ross M odel...........................................................................1115 8.4.5.5. Herschel-B ulkley Model f or B ingham P lastics ........................................................1116 8.4.5.5.1. Inputs f or the H erschel-B ulkley Model.........................................................1117 8.5.Thermal C onduc tivit y............................................................................................................1117 8.5.1. Constan t Thermal C onduc tivit y.....................................................................................1118 8.5.2. Thermal C onduc tivit y as a F unction of Temp erature......................................................1118 8.5.3. Thermal C onduc tivit y Using K inetic Theor y...................................................................1119 8.5.4. Comp osition-D ependen t Thermal C onduc tivit y for M ultic omp onen t Mixtures...............1119 8.5.5. Anisotr opic Thermal C onduc tivit y for S olids ..................................................................1120 8.5.5.1. Anisotr opic Thermal C onduc tivit y........................................................................1121 8.5.5.2. Biaxial Thermal C onduc tivit y................................................................................1122 8.5.5.3. Orthotr opic Thermal C onduc tivit y........................................................................1123 8.5.5.4. Cylindr ical Or thotr opic Thermal C onduc tivit y.......................................................1125 8.5.5.5. Principal A xes and P rincipal Values .......................................................................1126 8.5.5.6. User-D efined A nisotr opic Thermal C onduc tivit y...................................................1128 8.6. User-D efined Sc alar (UDS) D iffusivit y.....................................................................................1129 8.6.1. Isotr opic D iffusion ........................................................................................................1129 8.6.2. Anisotr opic D iffusion ....................................................................................................1130 8.6.2.1. Anisotr opic D iffusivit y..........................................................................................1131 8.6.2.2. Orthotr opic D iffusivit y.........................................................................................1132 8.6.2.3. Cylindr ical Or thotr opic D iffusivit y........................................................................1134 8.6.3. User-D efined A nisotr opic D iffusivit y.............................................................................1135 8.7. Specific H eat Capacit y...........................................................................................................1136 8.7.1. Input of C onstan t Specific H eat Capacit y.......................................................................1136 8.7.2. Specific H eat Capacit y as a F unction of Temp erature.....................................................1136 8.7.3. Defining S pecific H eat Capacit y Using K inetic Theor y....................................................1137 8.7.4. Specific H eat Capacit y as a F unction of C omp osition .....................................................1137 8.8. Radia tion P roperties ..............................................................................................................1137 8.8.1. Absor ption C oefficien t..................................................................................................1138 8.8.1.1. Inputs f or a C onstan t Absor ption C oefficien t........................................................1138 8.8.1.2. Inputs f or a C omp osition-D ependen t Absor ption C oefficien t................................1138 8.8.1.2.1. Path Length Inputs ......................................................................................1139 8.8.1.2.1.1. Inputs f or a N on-G ray Radia tion A bsor ption C oefficien t.......................1139 8.8.1.2.1.2. Effect of P articles and S oot on the A bsor ption C oefficien t....................1139 8.8.2. Scattering C oefficien t...................................................................................................1140 8.8.2.1. Inputs f or a C onstan t Scattering C oefficien t..........................................................1140 8.8.2.2. Inputs f or the Sc attering P hase F unction ..............................................................1140 8.8.2.2.1. Isotr opic P hase F unction .............................................................................1140 8.8.2.2.2. Linear-A nisotr opic P hase F unction ..............................................................1140 8.8.2.2.3. Delta-E ddingt on P hase F unction .................................................................1140 8.8.2.2.4. User-D efined P hase F unction ......................................................................1140 8.8.3. Refractive Inde x............................................................................................................1140 8.8.4. Reporting the R adia tion P roperties ...............................................................................1141 8.9. Mass D iffusion C oefficien ts....................................................................................................1141 8.9.1. Fickian D iffusion ...........................................................................................................1141 8.9.2. Full M ultic omp onen t Diffusion .....................................................................................1142 8.9.2.1. Gener al Theor y....................................................................................................1142 8.9.2.2. Maxwell-S tefan E qua tions ....................................................................................1142 8.9.3. Anisotr opic S pecies D iffusion ........................................................................................1144 8.9.4. Thermal D iffusion C oefficien ts......................................................................................1144 8.9.4.1. Thermal D iffusion C oefficien t Inputs .....................................................................1145 8.9.5. Mass D iffusion C oefficien t Inputs ..................................................................................1146 xxixRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide8.9.5.1. Constan t Dilute Approxima tion Inputs .................................................................1147 8.9.5.2. Dilute Approxima tion Inputs ................................................................................1147 8.9.5.3. Multic omp onen t Metho d Inputs ..........................................................................1148 8.9.5.4. Unity Lewis N umb er............................................................................................1149 8.9.6. Mass D iffusion C oefficien t Inputs f or Turbulen t Flow.....................................................1150 8.10. Standar d State En thalpies ....................................................................................................1150 8.11. Standar d State En tropies .....................................................................................................1151 8.12. Unbur nt Thermal D iffusivit y................................................................................................1151 8.13. Kinetic Theor y Paramet ers...................................................................................................1151 8.13.1. Inputs f or K inetic Theor y.............................................................................................1152 8.14. Operating P ressur e..............................................................................................................1152 8.14.1. The S ignific ance of Op erating P ressur e........................................................................1152 8.14.2. Operating P ressur e, Gauge P ressur e, and A bsolut e Pressur e.........................................1153 8.14.3. Setting the Op erating P ressur e...................................................................................1153 8.15. Reference Pressur e Location ................................................................................................1154 8.15.1. Actual R eference Pressur e Location .............................................................................1154 8.16. Real G as M odels ..................................................................................................................1154 8.16.1. Introduction ...............................................................................................................1155 8.16.2. Choosing a R eal G as M odel.........................................................................................1157 8.16.3. Cubic E qua tion of S tate Models ..................................................................................1157 8.16.3.1. Overview and Limita tions ..................................................................................1157 8.16.3.2. Equa tion of S tate...............................................................................................1159 8.16.3.3. Enthalp y, Entropy, and S pecific H eat Calcula tions ................................................1161 8.16.3.4. Critical Constan ts for P ure Comp onen ts..............................................................1162 8.16.3.5. Calcula tions f or M ixtures....................................................................................1163 8.16.3.5.1. Using the C ubic E qua tion of S tate Real G as M odels ....................................1165 8.16.3.5.2. Solution S trategies and C onsider ations f or C ubic E qua tions of S tate Real G as Models .....................................................................................................................1169 8.16.3.5.3. Using the C ubic E quation of S tate Models with the Lagr angian D ispersed P hase Models .....................................................................................................................1171 8.16.3.5.4. Postpr ocessing the C ubic E qua tions of S tate Real G as M odel......................1173 8.16.4. The NIST R eal G as M odels ...........................................................................................1173 8.16.4.1. Limita tions of the NIST R eal G as M odels .............................................................1174 8.16.4.2. The REFPR OP v9.1 D atabase ...............................................................................1174 8.16.4.3. Using the NIST R eal G as M odels ..........................................................................1177 8.16.4.3.1. Activating the NIST R eal G as M odel............................................................1177 8.16.4.3.2. Creating F ull NIST L ook-up Tables .............................................................1178 8.16.4.3.3. Creating B inar y Mixture Saturation Tables f or B inar y Mixtures....................1181 8.16.4.3.4. Changing the REFPR OP Libr ary and F luid F iles ...........................................1183 8.16.4.4. Solution S trategies and C onsider ations f or NIST R eal G as M odel S imula tion ........1184 8.16.4.4.1. Writing Your C ase F ile................................................................................1184 8.16.4.4.2. Postpr ocessing ..........................................................................................1184 8.16.5. The U ser-D efined R eal G as M odel................................................................................1185 8.16.5.1. Limita tions of the U ser-D efined R eal G as M odel..................................................1185 8.16.5.2. Writing the UDR GM C F unction Libr ary...............................................................1187 8.16.5.3. Compiling Your UDR GM C F unctions and B uilding a S hared Libr ary File...............1191 8.16.5.3.1. Compiling the UDR GM U sing the G raphic al In terface.................................1191 8.16.5.3.2. Compiling the UDR GM U sing the Text Interface.........................................1191 8.16.5.3.3. Loading the UDR GM S hared Libr ary File.....................................................1192 8.16.5.4. UDR GM Example: Ideal G as E qua tion of S tate.....................................................1193 8.16.5.4.1. Ideal G as UDR GM C ode Listing ..................................................................1194 8.16.5.5. Additional UDR GM Examples .............................................................................1196 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. xxxUser's G uide9. Modeling B asic F luid F low...........................................................................................................1197 9.1. User-D efined Sc alar (UDS) Transp ort Equa tions ......................................................................1197 9.1.1. Introduction .................................................................................................................1197 9.1.2. UDS Theor y..................................................................................................................1197 9.1.2.1. Single P hase F low................................................................................................1198 9.1.2.2. Multiphase F low..................................................................................................1198 9.1.3. Setting U p UDS E qua tions in ANSY S Fluen t...................................................................1199 9.1.3.1. Single P hase F low................................................................................................1200 9.1.3.2. Multiphase F low..................................................................................................1205 9.2. Periodic F lows.......................................................................................................................1206 9.2.1. Overview and Limita tions .............................................................................................1206 9.2.1.1. Overview .............................................................................................................1207 9.2.1.2. Limita tions f or M odeling S treamwise-P eriodic F low..............................................1207 9.2.2. User Inputs f or the P ressur e-Based S olver......................................................................1208 9.2.2.1. Setting P aramet ers f or the C alcula tion of β...........................................................1209 9.2.3. User Inputs f or the D ensit y-Based S olvers.....................................................................1210 9.2.4. Monit oring the Value of the P ressur e Gradien t..............................................................1210 9.2.5. Postpr ocessing f or S treamwise-P eriodic F lows..............................................................1210 9.3. Swirling and R otating F lows..................................................................................................1211 9.3.1. Overview of S wirling and R otating F lows......................................................................1212 9.3.1.1. Axisymmetr ic Flows with S wirl or R otation ...........................................................1212 9.3.1.1.1. Momen tum C onser vation E qua tion f or Swirl Velocity...................................1212 9.3.1.2. Three-D imensional S wirling F lows........................................................................1212 9.3.1.3. Flows Requir ing a M oving R eference Frame ..........................................................1213 9.3.2. Turbulenc e Modeling in S wirling F lows.........................................................................1213 9.3.3. Mesh S etup f or Swirling and R otating F lows..................................................................1213 9.3.3.1. Coordina te System R estrictions ............................................................................1213 9.3.3.2. Mesh S ensitivit y in S wirling and R otating F lows....................................................1214 9.3.4. Modeling A xisymmetr ic Flows with S wirl or R otation .....................................................1214 9.3.4.1. Problem S etup f or A xisymmetr ic Swirling F lows...................................................1215 9.3.4.2. Solution S trategies f or A xisymmetr ic Swirling F lows.............................................1215 9.3.4.2.1. Step-B y-Step S olution P rocedur es for A xisymmetr ic Swirling F lows..............1216 9.3.4.2.2. Impr oving S olution S tabilit y by Gradually Incr easing the R otational or S wirl Speed .......................................................................................................................1217 9.3.4.2.2.1. Postpr ocessing f or A xisymmetr ic Swirling F lows..................................1217 9.4. Compr essible F lows..............................................................................................................1217 9.4.1. When t o Use the C ompr essible F low M odel...................................................................1218 9.4.2. Physics of C ompr essible F lows......................................................................................1219 9.4.2.1. Basic E qua tions f or C ompr essible F lows................................................................1219 9.4.2.2. The C ompr essible F orm of the G as La w................................................................1219 9.4.3. Modeling Inputs f or C ompr essible F lows.......................................................................1220 9.4.3.1. Boundar y Conditions f or C ompr essible F lows.......................................................1221 9.4.4. Floating Op erating P ressur e..........................................................................................1221 9.4.4.1. Limita tions ..........................................................................................................1221 9.4.4.2. Theor y.................................................................................................................1221 9.4.4.3. Enabling F loating Op erating P ressur e...................................................................1222 9.4.4.4. Setting the Initial Value f or the F loating Op erating P ressur e..................................1222 9.4.4.5. Storage and R eporting of the F loating Op erating P ressur e....................................1222 9.4.4.6. Monit oring A bsolut e Pressur e..............................................................................1222 9.4.5. Solution S trategies f or C ompr essible F lows...................................................................1223 9.4.6. Reporting of R esults f or C ompr essible F lows.................................................................1223 9.5. Inviscid F lows........................................................................................................................1224 xxxiRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide9.5.1. Setting U p an In viscid F low M odel................................................................................1224 9.5.2. Solution S trategies f or In viscid F lows............................................................................1225 9.5.3. Postpr ocessing f or In viscid F lows..................................................................................1225 10. Modeling F lows with M oving Ref erenc e Frames ......................................................................1227 10.1. Introduction ........................................................................................................................1227 10.2. Flow in S ingle M oving R eference Frames (SRF) .....................................................................1229 10.2.1. Mesh S etup f or a S ingle M oving R eference Frame ........................................................1229 10.2.2. Setting U p a S ingle M oving R eference Frame P roblem .................................................1230 10.2.2.1. Choosing the R elative or A bsolut e Velocity Formula tion ......................................1232 10.2.2.1.1. Example ....................................................................................................1232 10.2.3. Solution S trategies f or a S ingle M oving R eference Frame .............................................1234 10.2.3.1. Gradual Incr ease of the R otational S peed t o Impr ove Solution S tabilit y...............1234 10.2.4. Postpr ocessing f or a S ingle M oving R eference Frame ...................................................1235 10.3. Flow in M ultiple M oving R eference Frames ..........................................................................1236 10.3.1. The M ultiple R eference Frame M odel..........................................................................1237 10.3.1.1. Overview ...........................................................................................................1237 10.3.1.2. Limita tions ........................................................................................................1237 10.3.2. The M ixing P lane M odel..............................................................................................1239 10.3.2.1. Overview ...........................................................................................................1239 10.3.2.2. Limita tions ........................................................................................................1239 10.3.3. Mesh S etup f or a M ultiple M oving R eference Frame ....................................................1240 10.3.4. Setting U p a M ultiple M oving R eference Frame P roblem .............................................1240 10.3.4.1. Setting U p M ultiple R eference Frames ................................................................1240 10.3.4.2. Setting U p the M ixing P lane M odel....................................................................1243 10.3.4.2.1. Modeling Options .....................................................................................1246 10.3.4.2.1.1. Fixing the P ressur e Level for an Inc ompr essible F low.........................1247 10.3.4.2.1.2. Conser ving S wirl Across the M ixing P lane ..........................................1247 10.3.4.2.1.3. Conser ving Total En thalp y Across the M ixing P lane ...........................1247 10.3.5. Solution S trategies f or MRF and M ixing P lane P roblems ...............................................1248 10.3.5.1. MRF M odel........................................................................................................1248 10.3.5.2. Mixing P lane M odel...........................................................................................1248 10.3.6. Postpr ocessing f or MRF and M ixing P lane P roblems ....................................................1248 10.3.7. Frozen G ust / Inlet D isturbanc e Flow M odeling ............................................................1249 11. Modeling F lows Using S liding and D ynamic M eshes ................................................................1251 11.1. Introduction ........................................................................................................................1251 11.2. Sliding M esh Examples ........................................................................................................1252 11.3. The S liding M esh Technique ................................................................................................1254 11.4. Sliding M esh In terface Shap es.............................................................................................1255 11.5. Using S liding M eshes ..........................................................................................................1257 11.5.1. Requir emen ts, Constr aints, and C onsider ations ............................................................1257 11.5.2. Setting U p the S liding M esh P roblem ..........................................................................1258 11.5.3. Solution S trategies f or Sliding M eshes .........................................................................1261 11.5.3.1. Saving C ase and D ata Files .................................................................................1261 11.5.3.2. Time-P eriodic S olutions .....................................................................................1261 11.5.4. Postpr ocessing f or S liding M eshes ..............................................................................1263 11.6. Using D ynamic M eshes .......................................................................................................1264 11.6.1. Setting D ynamic M esh M odeling P aramet ers..............................................................1266 11.6.2. Dynamic M esh U pdate Metho ds.................................................................................1267 11.6.2.1. Smoothing M etho ds..........................................................................................1268 11.6.2.1.1. Diffusion-B ased S moothing .......................................................................1269 11.6.2.1.1.1. Diffusivit y Based on B oundar y Distanc e............................................1273 11.6.2.1.1.2. Diffusivit y Based on C ell Volume .......................................................1275 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. xxxiiUser's G uide11.6.2.1.1.3. Applic abilit y of the D iffusion-B ased S moothing M etho d....................1275 11.6.2.1.2. Spring-B ased S moothing ...........................................................................1275 11.6.2.1.2.1. Applic abilit y of the S pring-B ased S moothing M etho d.......................1279 11.6.2.1.3. Linear ly Elastic S olid B ased S moothing M etho d.........................................1279 11.6.2.1.3.1. Applic abilit y of the Linear ly Elastic S olid B ased S moothing M etho d....1281 11.6.2.1.4. Smoothing fr om a R eference Position ........................................................1281 11.6.2.1.5. Laplacian S moothing M etho d....................................................................1282 11.6.2.1.6. Boundar y La yer Smoothing M etho d..........................................................1282 11.6.2.2. Dynamic La yering..............................................................................................1285 11.6.2.2.1. Applic abilit y of the D ynamic La yering M etho d...........................................1288 11.6.2.3. Remeshing M etho ds..........................................................................................1289 11.6.2.3.1. Local Remeshing M etho d..........................................................................1292 11.6.2.3.1.1. Local Cell R emeshing M etho d...........................................................1293 11.6.2.3.1.2. Local Face Remeshing M etho d..........................................................1293 11.6.2.3.1.2.1. Applic abilit y of the L ocal Face Remeshing M etho d...................1294 11.6.2.3.1.3. Local Remeshing B ased on S izing F unction .......................................1294 11.6.2.3.2. Cell Z one R emeshing M etho d....................................................................1299 11.6.2.3.2.1. Limita tions of the C ell Z one R emeshing M etho d................................1300 11.6.2.3.3. Face Region R emeshing M etho d................................................................1300 11.6.2.3.3.1. Face Region R emeshing with Wedge C ells in P rism La yers..................1301 11.6.2.3.3.2. Applic abilit y of the F ace Region R emeshing M etho d.........................1303 11.6.2.3.4. CutCell Z one R emeshing M etho d..............................................................1304 11.6.2.3.4.1. Applic abilit y of the C utCell Z one R emeshing M etho d........................1306 11.6.2.3.4.2. Using the C utCell Z one R emeshing M etho d......................................1306 11.6.2.3.4.3. Applying the C utCell Z one R emeshing M etho d M anually ..................1307 11.6.2.3.5. 2.5D Sur face Remeshing M etho d...............................................................1308 11.6.2.3.5.1. Applic abilit y of the 2.5D Sur face Remeshing M etho d.........................1309 11.6.2.3.5.2. Using the 2.5D M odel.......................................................................1309 11.6.2.4. Volume M esh U pdate Procedur e........................................................................1312 11.6.2.5. Transien t Consider ations f or R emeshing and La yering ........................................1312 11.6.3. Feature Detection .......................................................................................................1313 11.6.3.1. Applic abilit y of F eature Detection ......................................................................1313 11.6.4. In-C ylinder S ettings ....................................................................................................1313 11.6.4.1. Using the In-C ylinder Option ..............................................................................1318 11.6.4.1.1. Overview ..................................................................................................1318 11.6.4.1.2. Defining the M esh Topology......................................................................1319 11.6.4.1.3. Defining M otion/G eometr y Attribut es of M esh Z ones ................................1322 11.6.4.1.4. Defining Valve Op ening and C losur e..........................................................1328 11.6.5. Six DOF S olver Settings ...............................................................................................1328 11.6.5.1. Setting R igid B ody Motion A ttribut es for the S ix DOF S olver................................1330 11.6.6. Implicit U pdate Settings .............................................................................................1332 11.6.7. Contact Detection S ettings .........................................................................................1334 11.6.8. Defining D ynamic M esh E vents...................................................................................1336 11.6.8.1. Procedur e for D efining E vents............................................................................1336 11.6.8.2. Defining E vents for In-C ylinder A pplic ations .......................................................1339 11.6.8.2.1. Events.......................................................................................................1340 11.6.8.2.2. Changing the Z one Type...........................................................................1340 11.6.8.2.3. Copying Z one B oundar y Conditions ..........................................................1340 11.6.8.2.4. Activating a C ell Z one ................................................................................1340 11.6.8.2.5. Deactivating a C ell Z one ............................................................................1340 11.6.8.2.6. Creating a S liding In terface........................................................................1340 11.6.8.2.7. Deleting a S liding In terface........................................................................1342 xxxiiiRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide11.6.8.2.8. Changing the M otion A ttribut e of a D ynamic Z one ....................................1342 11.6.8.2.9. Changing the Time S tep............................................................................1342 11.6.8.2.10. Changing the U nder-R elaxa tion F actor....................................................1342 11.6.8.2.11. Inser ting a B oundar y Zone La yer.............................................................1342 11.6.8.2.12. Remo ving a B oundar y Zone La yer............................................................1343 11.6.8.2.13. Inser ting an In terior Z one La yer...............................................................1343 11.6.8.2.14. Remo ving an In terior Z one La yer.............................................................1344 11.6.8.2.15. Inser ting a C ell La yer...............................................................................1344 11.6.8.2.16. Remo ving a C ell La yer.............................................................................1344 11.6.8.2.17. Executing a C ommand ............................................................................1345 11.6.8.2.18. Replacing the M esh .................................................................................1345 11.6.8.2.19. Resetting Iner t EGR ..................................................................................1345 11.6.8.2.20. Diesel U nsteady Flamelet R eset ...............................................................1345 11.6.8.3. Exp orting and Imp orting E vents.........................................................................1345 11.6.9. Specifying the M otion of D ynamic Z ones ....................................................................1345 11.6.9.1. Gener al Procedur e.............................................................................................1346 11.6.9.1.1. Creating a D ynamic Z one ..........................................................................1346 11.6.9.1.2. Modifying a D ynamic Z one ........................................................................1346 11.6.9.1.3. Check ing the C enter of G ravity..................................................................1346 11.6.9.1.4. Deleting a D ynamic Z one ..........................................................................1346 11.6.9.2. Stationar y Zones ................................................................................................1346 11.6.9.3. Rigid B ody Motion .............................................................................................1349 11.6.9.4. Deforming M otion .............................................................................................1354 11.6.9.5. User-D efined M otion .........................................................................................1359 11.6.9.5.1. Specifying B oundar y La yer D eformation S moothing ..................................1360 11.6.9.6. System C oupling M otion ....................................................................................1361 11.6.9.7. Intrinsic FSI M otion ............................................................................................1362 11.6.9.8. Solution S tabiliza tion f or D ynamic M esh B oundar y Zones ...................................1364 11.6.9.9. Solid-B ody Kinema tics .......................................................................................1365 11.6.10. Previewing the D ynamic M esh ..................................................................................1368 11.6.10.1. Previewing Z one M otion ..................................................................................1368 11.6.10.2. Previewing M esh M otion ..................................................................................1369 11.6.11. Steady-State Dynamic M esh A pplic ations ..................................................................1370 11.6.11.1. An Example of S teady-State Dynamic M esh U sage ............................................1372 12. Modeling Turbulenc e................................................................................................................1375 12.1. Introduction ........................................................................................................................1375 12.2. Choosing a Turbulenc e Model.............................................................................................1377 12.2.1. Reynolds A veraged N avier-S tokes (R ANS) Turbulenc e Models ......................................1378 12.2.1.1. Spalar t-Allmar as One-E qua tion M odel................................................................1378 12.2.1.2. k-ε Models .........................................................................................................1378 12.2.1.3. k-ω Models ........................................................................................................1379 12.2.1.4. Gener alized k-ω (GEK O) M odel...........................................................................1379 12.2.1.5. Reynold S tress M odels .......................................................................................1381 12.2.1.6. Laminar-T urbulen t Transition M odels .................................................................1382 12.2.1.7. Curvature Correction f or the S palar t-Allmar as and Two-Equa tion M odels ............1383 12.2.1.8. Production Limit ers f or Two-Equa tion M odels .....................................................1383 12.2.1.9. Model Enhanc emen ts........................................................................................1383 12.2.1.10. Wall Treatmen t for R ANS M odels .......................................................................1383 12.2.1.11. Grid Resolution f or R ANS M odels ......................................................................1384 12.2.2. Scale-R esolving S imula tion (SRS) M odels .....................................................................1385 12.2.2.1. Large E ddy Simula tion (LES) ...............................................................................1385 12.2.2.2. Hybrid R ANS-LES M odels ...................................................................................1385 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. xxxivUser's G uide12.2.2.2.1. Scale-A daptiv e Simula tion (SAS) ................................................................1386 12.2.2.2.2. Detached E ddy Simula tion (DES) ...............................................................1386 12.2.2.2.3. Shielded D etached E ddy Simula tion (SDES) and S tress-B lended E ddy Simula tion (SBES) .......................................................................................................................1387 12.2.2.3. Zonal M odeling and Emb edded LES (ELES) .........................................................1388 12.2.3. Grid Resolution SRS M odels ........................................................................................1388 12.2.3.1. Wall B oundar y La yers.........................................................................................1388 12.2.3.2. Free S hear F lows................................................................................................1388 12.2.4. Numer ics S ettings f or SRS M odels ...............................................................................1389 12.2.4.1. Time D iscretiza tion ............................................................................................1389 12.2.4.2. Spatial D iscretiza tion .........................................................................................1389 12.2.4.3. Iterative Scheme ................................................................................................1390 12.2.4.3.1. Convergenc e Control.................................................................................1391 12.2.5. Model Hier archy.........................................................................................................1391 12.3. Steps in U sing a Turbulenc e Model......................................................................................1392 12.4. Setting U p the S palar t-Allmar as M odel................................................................................1395 12.5. Setting U p the k- ε Model.....................................................................................................1395 12.5.1. Setting U p the S tandar d or R ealizable k- ε Model.........................................................1396 12.5.2. Setting U p the RNG k- ε Model.....................................................................................1398 12.6. Setting U p the k- ω Model....................................................................................................1401 12.6.1. Setting U p the S tandar d k-ω Model.............................................................................1401 12.6.2. Setting U p the B aseline (BSL) k- ω Model......................................................................1402 12.6.3. Setting U p the S hear-S tress Transp ort k-ω Model.........................................................1404 12.6.4. Setting up the G ener alized k-ω (GEK O) M odel.............................................................1406 12.7. Setting U p the Transition k-k l-ω Model.................................................................................1409 12.8. Setting U p the Transition SST M odel....................................................................................1409 12.9. Setting U p the In termitt ency Transition M odel.....................................................................1412 12.10. Setting U p the R eynolds S tress M odel................................................................................1413 12.11. Setting U p Sc ale-A daptiv e Simula tion (SAS) M odeling ........................................................1418 12.12. Setting U p the D etached E ddy Simula tion M odel...............................................................1420 12.12.1. Setting U p DES with the S palar t-Allmar as M odel.......................................................1420 12.12.2. Setting U p DES with the R ealizable k- ε Model............................................................1422 12.12.3. Setting U p DES with the SST k- ω Model.....................................................................1423 12.12.4. Setting U p DES with the BSL k- ω Model.....................................................................1425 12.12.5. Setting U p DES with the Transition SST M odel...........................................................1427 12.13. Setting U p the Lar ge E ddy Simula tion M odel.....................................................................1431 12.14. Model C onstan ts...............................................................................................................1432 12.15. Setting U p the Emb edded Lar ge E ddy Simula tion (ELES) M odel..........................................1432 12.16. Setup Options f or A ll Turbulenc e Modeling ........................................................................1436 12.16.1. Including the Viscous H eating E ffects........................................................................1437 12.16.2. Including Turbulenc e Gener ation D ue t o Buoyancy...................................................1437 12.16.3. Including the C urvature Correction f or the S palar t-Allmar as and Two-Equation Turbulenc e Models .................................................................................................................................1437 12.16.4. Including the C ompr essibilit y Effects Option .............................................................1438 12.16.5. Including P roduction Limit ers f or Two-Equa tion M odels ............................................1438 12.16.6. Including the In termitt ency Transition M odel............................................................1439 12.16.7. Vorticity- and S train/V orticity-Based P roduction ........................................................1439 12.16.8. Delayed D etached E ddy Simula tion (DDES) ...............................................................1440 12.16.9. Differential Viscosity Modific ation .............................................................................1440 12.16.10. Swirl Modific ation ...................................................................................................1440 12.16.11. Low-Re Corrections .................................................................................................1440 12.16.12. Shear F low Corrections ...........................................................................................1440 xxxvRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide12.16.13. Turbulenc e Damping ..............................................................................................1441 12.16.14. Including P ressur e Gradien t Effects.........................................................................1441 12.16.15. Including Thermal E ffects........................................................................................1441 12.16.16. Including the Wall R eflec tion Term..........................................................................1441 12.16.17. Solving the k E qua tion t o Obtain Wall B oundar y Conditions .....................................1442 12.16.18. Quadr atic P ressur e-Strain M odel.............................................................................1442 12.16.19. Stress-Omega and S tress-BSL M odels ......................................................................1442 12.16.20. Sub grid-Sc ale M odel...............................................................................................1443 12.16.21. Customizing the Turbulen t Viscosity........................................................................1443 12.16.22. Customizing the Turbulen t Prandtl and Schmidt N umb ers.......................................1443 12.16.23. Modeling Turbulenc e with N on-N ewtonian F luids ...................................................1444 12.16.24. Including Sc ale-A daptiv e Simula tion with ω-Based UR ANS M odels ...........................1444 12.16.25. Including D etached E ddy Simula tion with the Transition SST M odel.........................1444 12.16.26. Including the SDES or SBES M odel with BSL, SST , and Transition SST M odels .............1444 12.16.27. Shielding F unctions f or the BSL / SST / Transition SST D etached E ddy Simula tion M od- el..........................................................................................................................................1448 12.17. Defining Turbulenc e Boundar y Conditions .........................................................................1448 12.17.1. Wall R oughness E ffects.............................................................................................1448 12.17.2. The S palar t-Allmar as M odel......................................................................................1449 12.17.3. k-ε Models and k- ω Models .......................................................................................1449 12.17.4. Reynolds S tress M odel..............................................................................................1449 12.17.5. Large E ddy Simula tion M odel...................................................................................1451 12.18. Providing an Initial G uess f or k and ε (or k and ω)................................................................1452 12.19. Solution S trategies f or Turbulen t Flow Simula tions .............................................................1452 12.19.1. Mesh G ener ation ......................................................................................................1453 12.19.2. Accur acy..................................................................................................................1453 12.19.3. Convergenc e............................................................................................................1453 12.19.4. RSM-S pecific S olution S trategies ...............................................................................1454 12.19.4.1. Under-R elaxa tion of the R eynolds S tresses .......................................................1454 12.19.4.2. Disabling C alcula tion U pdates of the R eynolds S tresses ....................................1454 12.19.4.3. Residual R eporting f or the RSM ........................................................................1455 12.19.5. LES-S pecific S olution S trategies ................................................................................1455 12.19.5.1. Temp oral D iscretiza tion ....................................................................................1456 12.19.5.2. Spatial D iscretiza tion ........................................................................................1456 12.20. Postpr ocessing f or Turbulen t Flows....................................................................................1456 12.20.1. Custom F ield F unctions f or Turbulenc e......................................................................1464 12.20.2. Postpr ocessing Turbulen t Flow Statistics ...................................................................1465 12.20.3. Troublesho oting .......................................................................................................1466 13. Modeling H eat Transf er.............................................................................................................1467 13.1. Introduction ........................................................................................................................1467 13.2. Modeling C onduc tive and C onvective Heat Transf er.............................................................1467 13.2.1. Solving H eat Transf er Problems ...................................................................................1467 13.2.1.1. Limiting the P redic ted Temp erature Range .........................................................1469 13.2.1.2. Modeling H eat Transf er in Two Separ ated F luid R egions ......................................1469 13.2.2. Solution S trategies f or H eat Transf er M odeling ............................................................1470 13.2.2.1. Under-R elaxa tion of the Ener gy Equa tion ...........................................................1470 13.2.2.2. Under-R elaxa tion of Temp erature When the En thalp y Equa tion is S olved............1470 13.2.2.3. Disabling the S pecies D iffusion Term..................................................................1471 13.2.2.4. Step-b y-Step S olutions .......................................................................................1471 13.2.2.4.1. Decoupled F low and H eat Transf er C alcula tions .........................................1471 13.2.2.4.2. Coupled F low and H eat Transf er C alcula tions .............................................1471 13.2.2.5. Specifying a S olid Time st ep...............................................................................1471 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. xxxviUser's G uide13.2.2.5.1. Automa tic Time S tep C alcula tion ...............................................................1474 13.2.3. Postpr ocessing H eat Transf er Q uantities ......................................................................1474 13.2.3.1. Available Variables f or P ostpr ocessing ................................................................1474 13.2.3.2. Definition of En thalp y and Ener gy in R eports and D ispla ys..................................1474 13.2.3.3. Reporting H eat Transf er Through B oundar ies......................................................1474 13.2.3.4. Reporting H eat Transf er Through a Sur face.........................................................1475 13.2.3.5. Reporting A veraged H eat Transf er C oefficien ts...................................................1475 13.2.3.6. Exp orting H eat Flux D ata...................................................................................1475 13.2.4. Natural Convection and B uoyancy-Driven F lows..........................................................1476 13.2.4.1. Modeling N atural Convection in a C losed D omain ..............................................1476 13.2.4.2. The B oussinesq M odel.......................................................................................1476 13.2.4.3. Limita tions of the B oussinesq M odel..................................................................1477 13.2.4.4. Steps in S olving B uoyancy-Driven F low Problems ...............................................1477 13.2.4.5. Operating D ensit y..............................................................................................1479 13.2.4.5.1. Setting the Op erating D ensit y...................................................................1480 13.2.4.6. Solution S trategies f or B uoyancy-Driven F lows...................................................1480 13.2.4.6.1. Guidelines f or S olving High-R ayleigh-N umb er Flows..................................1480 13.2.4.7. Postpr ocessing B uoyancy-Driven F lows..............................................................1481 13.2.5. Shell C onduc tion C onsider ations ................................................................................1481 13.2.5.1. Introduction ......................................................................................................1481 13.2.5.2. Physical Treatmen t.............................................................................................1482 13.2.5.3. Limita tions of S hell C onduc tion Walls.................................................................1483 13.2.5.4. Managing S hell C onduc tion Walls ......................................................................1484 13.2.5.5. Initializing S hells ................................................................................................1486 13.2.5.6. Locking the Temp erature for Shells .....................................................................1487 13.2.5.7. Postpr ocessing S hells .........................................................................................1487 13.3. Modeling R adia tion .............................................................................................................1489 13.3.1. Using the R adia tion M odels ........................................................................................1489 13.3.2. Setting U p the P-1 M odel with N on-G ray Radia tion .....................................................1491 13.3.3. Setting U p the DTRM ..................................................................................................1492 13.3.3.1. Defining the R ays...............................................................................................1492 13.3.3.2. Controlling the C lusters......................................................................................1493 13.3.3.3. Controlling the R ays...........................................................................................1494 13.3.3.4. Writing and R eading the DTRM R ay File..............................................................1494 13.3.3.5. Displa ying the C lusters.......................................................................................1495 13.3.4. Setting U p the S2S M odel...........................................................................................1495 13.3.4.1. View F actors and C lustering S ettings ..................................................................1497 13.3.4.1.1. Forming Sur face Clusters...........................................................................1498 13.3.4.1.1.1. Setting the S plit A ngle f or C lusters....................................................1501 13.3.4.1.2. Setting U p the View F actor C alcula tion ......................................................1501 13.3.4.1.2.1. Selec ting the B asis f or C omputing View F actors.................................1501 13.3.4.1.2.2. Selec ting the M etho d for C omputing View F actors............................1502 13.3.4.1.2.3. Accoun ting f or B locking Sur faces......................................................1503 13.3.4.1.2.4. Specifying B oundar y Zone P articipa tion ............................................1503 13.3.4.2. Computing View F actors....................................................................................1505 13.3.4.2.1. Computing View F actors Inside ANSY S Fluen t............................................1505 13.3.4.2.2. Computing View F actors Outside ANSY S Fluen t.........................................1507 13.3.4.3. Reading View F actors in to ANSY S Fluen t.............................................................1509 13.3.5. Setting U p the DO M odel............................................................................................1509 13.3.5.1. Angular D iscretiza tion ........................................................................................1509 13.3.5.2. Defining N on-G ray Radia tion f or the DO M odel..................................................1510 13.3.5.3. Enabling DO/Ener gy Coupling ............................................................................1512 xxxviiRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide13.3.6. Setting U p the MC M odel............................................................................................1512 13.3.7. Defining M aterial P roperties f or R adia tion ...................................................................1513 13.3.7.1. Absor ption C oefficien t for a N on-G ray Model......................................................1514 13.3.7.2. Refractive Inde x for a N on-G ray Model................................................................1514 13.3.8. Defining B oundar y Conditions f or R adia tion ...............................................................1514 13.3.8.1. Inlet and Exit B oundar y Conditions .....................................................................1514 13.3.8.1.1. Emissivit y..................................................................................................1514 13.3.8.1.2. Black B ody Temp erature............................................................................1515 13.3.8.2. Wall B oundar y Conditions f or the DTRM, and the P-1, S2S, and R osseland M od- els..................................................................................................................................1515 13.3.8.2.1. Boundar y Conditions f or the S2S M odel.....................................................1516 13.3.8.3. Wall B oundar y Conditions f or the DO M odel.......................................................1516 13.3.8.3.1. Opaque Walls ............................................................................................1516 13.3.8.3.2. Semi-T ranspar ent Walls .............................................................................1519 13.3.8.4. Wall B oundar y Conditions f or the MC M odel.......................................................1522 13.3.8.4.1. Opaque Walls ............................................................................................1523 13.3.8.4.2. Semi-T ranspar ent Walls .............................................................................1529 13.3.8.5. Solid C ell Z ones C onditions f or the DO or MC M odels ..........................................1530 13.3.8.6. Thermal B oundar y Conditions ............................................................................1531 13.3.9. Solution S trategies f or R adia tion M odeling ..................................................................1531 13.3.9.1. P-1 M odel S olution P aramet ers..........................................................................1532 13.3.9.2. DTRM S olution P aramet ers.................................................................................1532 13.3.9.3. S2S S olution P aramet ers....................................................................................1534 13.3.9.4. DO S olution P aramet ers.....................................................................................1534 13.3.9.5. MC S olution P aramet ers.....................................................................................1534 13.3.9.6. Running the C alcula tion .....................................................................................1535 13.3.9.6.1. Residual R eporting f or the P-1 M odel.........................................................1535 13.3.9.6.2. Residual R eporting f or the DO M odel.........................................................1535 13.3.9.6.3. Residual R eporting f or the DTRM ...............................................................1535 13.3.9.6.4. Residual R eporting f or the S2S M odel........................................................1535 13.3.9.6.5. Disabling the U pdate of the R adia tion F luxes.............................................1536 13.3.10. Postpr ocessing R adia tion Q uantities .........................................................................1536 13.3.10.1. Available Variables f or P ostpr ocessing ..............................................................1536 13.3.10.2. Reporting R adia tive Heat Transf er Through B oundar ies.....................................1537 13.3.10.3. Overall H eat Balanc es When U sing the DTRM ....................................................1538 13.3.10.4. Displa ying R ays and C lusters f or the DTRM .......................................................1538 13.3.10.4.1. Displa ying C lusters..................................................................................1538 13.3.10.4.2. Displa ying R ays.......................................................................................1539 13.3.10.4.3. Including the M esh in the D ispla y............................................................1539 13.3.10.5. Reporting R adia tion in the S2S M odel...............................................................1539 13.3.11. Solar L oad M odel......................................................................................................1540 13.3.11.1. Introduction ....................................................................................................1541 13.3.11.2. Solar R ay Tracing ..............................................................................................1541 13.3.11.2.1. Shading A lgor ithm ..................................................................................1542 13.3.11.2.2. Glazing M aterials.....................................................................................1543 13.3.11.2.3. Inputs .....................................................................................................1543 13.3.11.3. Solar Ir radia tion ...............................................................................................1544 13.3.11.4. Solar C alcula tor................................................................................................1545 13.3.11.4.1. Inputs/Outputs .......................................................................................1545 13.3.11.4.2. Theor y....................................................................................................1546 13.3.11.4.3. Computa tion of L oad D istribution ...........................................................1547 13.3.11.5. Using the S olar L oad M odel..............................................................................1548 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. xxxviiiUser's G uide13.3.11.5.1. User-D efined F unctions (UDFs) f or S olar L oad ..........................................1548 13.3.11.5.2. Setting U p the S olar L oad M odel..............................................................1548 13.3.11.5.3. Setting B oundar y Conditions f or S olar L oading ........................................1554 13.3.11.5.4. Solar R ay Tracing .....................................................................................1554 13.3.11.5.5. Solar Ir radia tion .......................................................................................1559 13.3.11.5.6. Text Interface-Only C ommands ................................................................1561 13.3.11.5.6.1. Automa tically S aving S olar R ay Tracing D ata....................................1561 13.3.11.5.6.2. Automa tically R eading S olar D ata...................................................1561 13.3.11.5.6.3. Aligning the C amer a Direction With the P osition of the Sun .............1562 13.3.11.5.6.4. Specifying the Sc attering F raction ...................................................1562 13.3.11.5.6.5. Applying the S olar L oad on A djac ent Fluid C ells ..............................1562 13.3.11.5.6.6. Specifying Q uad Tree R efinemen t Factor.........................................1562 13.3.11.5.6.7. Specifying G round R eflec tivit y........................................................1563 13.3.11.5.6.8. Reverting t o Single B and Implemen tation of DO M odel...................1563 13.3.11.5.6.9. Additional Text Interface Commands ...............................................1563 13.3.11.6. Postpr ocessing S olar L oad Q uantities ...............................................................1564 13.3.11.6.1. Solar L oad A nima tion a t Different Sun P ositions .......................................1565 13.3.11.6.2. Reporting and D ispla ying S olar L oad Q uantities .......................................1566 13.4. Modeling P eriodic H eat Transf er..........................................................................................1567 13.4.1. Overview and Limita tions ...........................................................................................1567 13.4.1.1. Overview ...........................................................................................................1567 13.4.1.2. Constr aints for P eriodic H eat Transf er Predic tions ...............................................1567 13.4.2. Theor y........................................................................................................................1568 13.4.2.1. Definition of the P eriodic Temp erature for C onstan t- Temp erature Wall C ondi- tions ...............................................................................................................................1568 13.4.2.2. Definition of the P eriodic Temp erature Change σ for Specified H eat Flux C ondi- tions ...............................................................................................................................1568 13.4.3. Using P eriodic H eat Transf er.......................................................................................1569 13.4.4. Solution S trategies f or P eriodic H eat Transf er..............................................................1570 13.4.5. Monit oring C onvergenc e............................................................................................1571 13.4.6. Postpr ocessing f or P eriodic H eat Transf er....................................................................1571 14. Modeling H eat Exchangers .......................................................................................................1573 14.1. Choosing a H eat Exchanger M odel......................................................................................1574 14.2. The D ual C ell M odel............................................................................................................1575 14.2.1. Restrictions ................................................................................................................1576 14.2.2. Using the D ual C ell H eat Exchanger M odel..................................................................1576 14.3. The M acro Heat Exchanger M odels ......................................................................................1585 14.3.1. Restrictions ................................................................................................................1586 14.3.2. Using the U ngroup ed M acro Heat Exchanger M odel...................................................1586 14.3.2.1. Selec ting the Z one f or the H eat Exchanger .........................................................1592 14.3.2.2. Specifying H eat Exchanger P erformanc e Data....................................................1592 14.3.2.3. Specifying the A uxiliar y Fluid Inlet and P ass-t o-Pass D irections ...........................1593 14.3.2.4. Defining the M acros...........................................................................................1593 14.3.2.4.1. Viewing the M acros...................................................................................1594 14.3.2.5. Specifying the A uxiliar y Fluid P roperties and C onditions .....................................1595 14.3.2.6. Setting the P ressur e-Drop P aramet ers and E ffectiveness .....................................1596 14.3.2.6.1. Using the D efault C ore Porosity Model.......................................................1596 14.3.2.6.2. Defining a N ew C ore Porosity Model..........................................................1596 14.3.2.6.3. Reading H eat Exchanger P aramet ers fr om an Ex ternal F ile..........................1597 14.3.2.6.4. Viewing the P aramet ers f or an Existing C ore Model....................................1598 14.3.3. Using the G roup ed M acro Heat Exchanger M odel........................................................1598 14.3.3.1. Selec ting the F luid Z ones f or the H eat Exchanger G roup .....................................1604 xxxixRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide14.3.3.2. Selec ting the U pstr eam H eat Exchanger G roup ..................................................1604 14.3.3.3. Specifying the A uxiliar y Fluid Inlet and P ass-t o-Pass D irections ...........................1605 14.3.3.4. Specifying the A uxiliar y Fluid P roperties .............................................................1605 14.3.3.5. Specifying Supplemen tary Auxiliar y Fluid S treams ..............................................1605 14.3.3.6. Initializing the A uxiliar y Fluid Temp erature.........................................................1605 14.4. Postpr ocessing f or the H eat Exchanger M odel.....................................................................1606 14.4.1. Heat Exchanger R eporting ..........................................................................................1606 14.4.1.1. Comput ed H eat Rejec tion ..................................................................................1606 14.4.1.2. Inlet/Outlet Temp erature................................................................................1607 14.4.1.3. Mass F low R ate................................................................................................1609 14.4.1.4. Specific H eat....................................................................................................1610 14.4.2. Total H eat Rejec tion R ate............................................................................................1610 14.5. Useful R eporting TUI C ommands .........................................................................................1611 15. Modeling S pecies Transp ort and F inite-Rate Chemistr y...........................................................1613 15.1. Volumetr ic Reactions ...........................................................................................................1614 15.1.1. Overview of U ser Inputs f or M odeling S pecies Transp ort and R eactions .......................1614 15.1.1.1. Mixture Materials...............................................................................................1615 15.1.2. Enabling S pecies Transp ort and R eactions and C hoosing the M ixture Material.............1616 15.1.3. Imp orting a Volumetr ic Kinetic M echanism in CHEMKIN F ormat..................................1624 15.1.3.1. Using ANSY S Encr ypted M echanisms .................................................................1625 15.1.3.2. Procedur e for Imp orting Volumetr ic CHEMKIN M echanisms ................................1625 15.1.3.3. CHEMKIN M echanisms Included with ANSY S Fluen t............................................1628 15.1.4. Defining P roperties f or the M ixture and I ts Constituen t Species ...................................1629 15.1.4.1. Defining the S pecies in the M ixture....................................................................1630 15.1.4.1.1. Overview of the S pecies D ialog Box...........................................................1631 15.1.4.1.2. Adding S pecies t o the M ixture...................................................................1632 15.1.4.1.3. Remo ving S pecies fr om the M ixture..........................................................1633 15.1.4.1.4. Assigning the Last S pecies .........................................................................1633 15.1.4.1.5. The N aming and Or dering of S pecies .........................................................1633 15.1.4.2. Defining R eactions .............................................................................................1634 15.1.4.2.1. Inputs f or R eaction D efinition ....................................................................1634 15.1.4.2.2. Defining S pecies and R eactions f or Fuel M ixtures.......................................1641 15.1.4.3. Defining Z one-B ased R eaction M echanisms .......................................................1642 15.1.4.3.1. Inputs f or R eaction M echanism D efinition ..................................................1642 15.1.4.4. Defining P hysical Properties f or the M ixture.......................................................1644 15.1.4.5. Defining P hysical Properties f or the S pecies in the M ixture..................................1645 15.1.5. Setting up C oal S imula tions with the C oal C alcula tor D ialog Box..................................1646 15.1.6. Defining C ell Z one and B oundar y Conditions f or Species .............................................1649 15.1.6.1. Diffusion a t Inlets with the P ressur e-Based S olver...............................................1649 15.1.7. Defining O ther S ources of C hemic al Species ...............................................................1650 15.1.8. Solution P rocedur es for C hemic al M ixing and F inite-Rate Chemistr y............................1650 15.1.8.1. Stabilit y and C onvergenc e in R eacting F lows......................................................1650 15.1.8.2. Two-Step S olution P rocedur e (Steady-sta te Only) ...............................................1650 15.1.8.3. Densit y Under-R elaxa tion ..................................................................................1651 15.1.8.4. Ignition in S teady-State Combustion S imula tions ...............................................1651 15.1.8.5. Solution of S tiff C hemistr y Systems ....................................................................1652 15.1.8.6. Eddy-Dissipa tion C oncept M odel S olution P rocedur e.........................................1652 15.1.9. Postpr ocessing f or S pecies C alcula tions ......................................................................1653 15.1.9.1. Averaged S pecies C oncentrations .......................................................................1654 15.2. Wall Sur face Reactions and C hemic al Vapor D eposition ........................................................1654 15.2.1. Overview of Sur face Species and Wall Sur face Reactions ..............................................1655 15.2.2. Imp orting a Sur face Kinetic M echanism in CHEMKIN F ormat........................................1655 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. xlUser's G uide15.2.2.1. Compa tibilit y and Limita tions f or G as P hase R eactions .......................................1657 15.2.2.2. Compa tibilit y and Limita tions f or Sur face Reactions ...........................................1658 15.2.3. Manual Inputs f or Wall Sur face Reactions ....................................................................1658 15.2.4. Including M ass Transf er To Sur faces in C ontinuit y........................................................1660 15.2.5. Wall Sur face Mass Transf er Effects in the Ener gy Equa tion ............................................1660 15.2.6. Modeling the H eat Release D ue t o Wall Sur face Reactions ...........................................1660 15.2.7. Solution P rocedur es for Wall Sur face Reactions ...........................................................1660 15.2.8. Postpr ocessing f or Sur face Reactions ..........................................................................1661 15.3. Particle Sur face Reactions ....................................................................................................1661 15.3.1. User Inputs f or P article Sur face Reactions ....................................................................1661 15.3.2. Modeling G aseous S olid C atalyz ed R eactions ..............................................................1662 15.3.3. Using the M ultiple Sur face Reactions M odel f or D iscrete-Phase P article C ombustion ....1662 15.4. Electrochemic al Reactions ...................................................................................................1663 15.4.1. Overview of E lectrochemic al Reactions .......................................................................1663 15.4.2. User Inputs f or E lectrochemic al Reactions ...................................................................1664 15.4.3. Electrochemic al Reaction E ffects in the Ener gy Equa tion .............................................1670 15.4.4. Electrochemic al Reaction E ffects in the S pecies Transp ort Equa tion .............................1671 15.4.5. Including M ass Transf er in C ontinuit y..........................................................................1671 15.4.6. Solution P rocedur es for Electrochemic al Reactions ......................................................1671 15.5. Species Transp ort Without R eactions ...................................................................................1671 15.6. Reacting C hannel M odel.....................................................................................................1673 15.6.1. Overview and Limita tions of the R eacting C hannel M odel...........................................1673 15.6.2. Enabling the R eacting C hannel M odel.........................................................................1673 15.6.3. Boundar y Conditions f or C hannel Walls.......................................................................1678 15.6.4. Postpr ocessing f or R eacting C hannel M odel C alcula tions ............................................1678 15.7. Reactor N etwork Model.......................................................................................................1680 15.7.1. Overview and Limita tions of the R eactor N etwork Model............................................1681 15.7.2. Solving R eactor N etworks...........................................................................................1681 15.7.3. Postpr ocessing R eactor N etwork Calcula tions .............................................................1684 16. Modeling N on-P remix ed C ombustion ......................................................................................1687 16.1. Steps in U sing the N on-P remix ed M odel..............................................................................1687 16.1.1. Preliminar ies..............................................................................................................1687 16.1.2. Defining the P roblem Type.........................................................................................1688 16.1.3. Overview of the P roblem S etup P rocedur e..................................................................1688 16.2. Setting U p the E quilibr ium C hemistr y Model.......................................................................1691 16.2.1. Choosing A diaba tic or N on-A diaba tic Options .............................................................1692 16.2.2. Specifying the Op erating P ressur e for the S ystem........................................................1693 16.2.3. Enabling a S econdar y Inlet S tream ..............................................................................1693 16.2.4. Choosing t o Define the F uel S tream(s) Empir ically .......................................................1694 16.2.5. Enabling the R ich F lammabilit y Limit (RFL) Option ......................................................1695 16.3. Setting U p the S teady and U nsteady Diffusion F lamelet M odels ...........................................1696 16.3.1. Choosing A diaba tic or N on-A diaba tic Options .............................................................1696 16.3.2. Specifying the Op erating P ressur e for the S ystem........................................................1696 16.3.3. Specifying a C hemic al M echanism F ile for Flamelet G ener ation ...................................1697 16.3.4. Imp orting a F lamelet ..................................................................................................1697 16.3.5. Using the U nsteady Diffusion F lamelet M odel.............................................................1697 16.3.6. Using the D iesel U nsteady Laminar F lamelet M odel.....................................................1698 16.3.6.1. Recommended S ettings f or In ternal C ombustion Engines ...................................1701 16.3.7. Resetting D iesel U nsteady Flamelets ...........................................................................1702 16.4. Defining the S tream C omp ositions ......................................................................................1702 16.4.1. Setting B oundar y Stream S pecies ...............................................................................1704 16.4.1.1. Including C ondensed S pecies .............................................................................1705 xliRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide16.4.2. Modifying the D atabase ..............................................................................................1705 16.4.3. Comp osition Inputs f or Empir ically-D efined F uel S treams ............................................1705 16.4.4. Modeling Liquid F uel C ombustion U sing the N on-P remix ed M odel..............................1705 16.4.5. Modeling C oal C ombustion U sing the N on-P remix ed M odel........................................1706 16.4.5.1. Defining the C oal C omp osition: Single-M ixture-Fraction M odels .........................1707 16.4.5.2. Defining the C oal C omp osition: Two-M ixture-Fraction M odels ............................1708 16.4.5.3. Additional C oal M odeling Inputs in ANSY S Fluen t...............................................1710 16.4.5.4. Postpr ocessing N on-P remix ed M odels of C oal C ombustion .................................1711 16.4.5.5. The C oal C alcula tor............................................................................................1711 16.5. Setting U p Control Paramet ers............................................................................................1713 16.5.1. Forcing the Ex clusion and Inclusion of E quilibr ium S pecies ..........................................1714 16.5.2. Defining the F lamelet C ontrols....................................................................................1715 16.5.3. Zeroing S pecies in the Initial U nsteady Flamelet ..........................................................1716 16.6. Calcula ting the F lamelets ....................................................................................................1716 16.6.1. Steady Diffusion F lamelet ...........................................................................................1716 16.6.2. Unsteady Diffusion F lamelet .......................................................................................1719 16.6.3. Saving the F lamelet D ata............................................................................................1720 16.6.4. Postpr ocessing the F lamelet D ata...............................................................................1720 16.7. Calcula ting the L ook-U p Tables ............................................................................................1723 16.7.1. Full Tabula tion of the Two-M ixture-Fraction M odel......................................................1727 16.7.2. Stabilit y Issues in C alcula ting C hemic al Equilibr ium L ook-U p Tables .............................1728 16.7.3. Saving the L ook-U p Tables ..........................................................................................1728 16.7.4. Postpr ocessing the L ook-U p Table D ata.......................................................................1728 16.8. Standar d Files f or D iffusion F lamelet M odeling ....................................................................1733 16.8.1. Sample S tandar d Diffusion F lamelet F ile.....................................................................1733 16.8.2. Missing S pecies ..........................................................................................................1734 16.9. Setting U p the Iner t Model..................................................................................................1735 16.9.1. Setting B oundar y Conditions f or Iner t Transp ort..........................................................1736 16.9.2. Initializing the Iner t Stream .........................................................................................1737 16.9.2.1. Iner t Fraction .....................................................................................................1737 16.9.2.2. Iner t Comp osition ..............................................................................................1737 16.9.3. Resetting Iner t EGR .....................................................................................................1737 16.10. Defining N on-P remix ed B oundar y Conditions ....................................................................1739 16.10.1. Input of M ixture Fraction B oundar y Conditions .........................................................1739 16.10.2. Diffusion a t Inlets ......................................................................................................1740 16.10.3. Input of Thermal B oundar y Conditions and F uel Inlet Velocities .................................1740 16.11. Defining N on-P remix ed P hysical Properties ........................................................................1740 16.12. Solution S trategies f or N on-P remix ed M odeling .................................................................1741 16.12.1. Single-M ixture-Fraction A pproach ............................................................................1741 16.12.2. Two-M ixture-Fraction A pproach ................................................................................1741 16.12.3. Starting a N on-P remix ed C alcula tion F rom a P revious C ase F ile..................................1742 16.12.3.1. Retrieving the PDF F ile D uring C ase F ile R eads ..................................................1742 16.12.4. Solving the F low Problem .........................................................................................1743 16.12.4.1. Under-R elaxa tion F actors f or PDF E qua tions .....................................................1743 16.12.4.2. Densit y Under-R elaxa tion .................................................................................1743 16.12.4.3. Tuning the PDF P aramet ers f or Two-M ixture-Fraction C alcula tions ....................1744 16.13. Postpr ocessing the N on-P remix ed M odel R esults ...............................................................1744 16.13.1. Postpr ocessing f or Iner t Calcula tions .........................................................................1746 17. Modeling P remix ed C ombustion ..............................................................................................1749 17.1. Limita tions of the P remix ed C ombustion M odel...................................................................1749 17.2. Using the P remix ed C ombustion M odel...............................................................................1749 17.2.1. Enabling the P remix ed C ombustion M odel.................................................................1750 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. xliiUser's G uide17.2.2. Choosing an A diaba tic or N on-A diaba tic M odel..........................................................1751 17.3. Setting U p the C-E qua tion and G-E qua tion M odels ..............................................................1751 17.3.1. Modifying the C onstan ts for the Z imon t Flame S peed M odel.......................................1752 17.3.2. Modifying the C onstan ts for the P eters F lame S peed M odel.........................................1753 17.3.3. Additional Options f or the G-E qua tion M odel..............................................................1753 17.3.4. Defining P hysical Properties f or the U nbur nt Mixture..................................................1753 17.3.5. Setting B oundar y Conditions f or the P rogress Variable ................................................1754 17.3.6. Initializing the P rogress Variable ..................................................................................1754 17.4. Setting U p the Ex tended C oher ent Flame M odel..................................................................1754 17.4.1. Modifying the ECFM M odel Variant.............................................................................1755 17.4.2. Modifying the C onstan ts for the ECFM F lame S peed C losur e........................................1755 17.4.3. Setting B oundar y Conditions f or the ECFM Transp ort..................................................1756 17.4.4. Initializing the F lame A rea D ensit y..............................................................................1756 17.5. Postpr ocessing f or P remix ed C ombustion C alcula tions .........................................................1756 17.5.1. Computing S pecies C oncentrations ............................................................................1758 18. Modeling P artially P remix ed C ombustion ................................................................................1759 18.1. Limita tions ..........................................................................................................................1759 18.2. Using the P artially P remix ed C ombustion M odel..................................................................1759 18.2.1. Setup and S olution P rocedur e....................................................................................1759 18.2.2. Imp orting a F lamelet ..................................................................................................1762 18.2.3. Flamelet G ener ated M anifold......................................................................................1762 18.2.3.1. Premix ed F lamelet G ener ated M anifolds ............................................................1762 18.2.3.2. Diffusion F lamelet G ener ated M anifolds .............................................................1764 18.2.4. Calcula ting the L ook-U p Tables ...................................................................................1766 18.2.4.1. Postpr ocessing the L ook-U p Tables with F lamelet G ener ated M anifolds ..............1769 18.2.5. Standar d Files f or Flamelet G ener ated M anifold M odeling ...........................................1771 18.2.5.1. Sample S tandar d FGM F ile.................................................................................1772 18.2.6. Modifying the U nbur nt Mixture Property Polynomials .................................................1773 18.2.7. Setting P remix F lame P ropaga tion P aramet ers............................................................1776 18.2.8. Modeling In C ylinder C ombustion ...............................................................................1777 18.2.9. Postpr ocessing f or FGM Sc alar Transp ort Calcula tions ..................................................1777 19. Modeling a C omp osition PDF Transp ort Problem ....................................................................1779 19.1. Limita tion ...........................................................................................................................1779 19.2. Steps f or U sing the C omp osition PDF Transp ort Model.........................................................1779 19.3. Enabling the Lagr angian C omp osition PDF Transp ort Model................................................1781 19.4. Enabling the E uler ian C omp osition PDF Transp ort Model.....................................................1783 19.4.1. Defining S pecies B oundar y Conditions ........................................................................1785 19.4.1.1. Equilibr ating Inlet S treams .................................................................................1786 19.5. Initializing the S olution .......................................................................................................1786 19.6. Monit oring the S olution ......................................................................................................1787 19.6.1. Running U nsteady Comp osition PDF Transp ort Simula tions ........................................1789 19.6.2. Running C ompr essible Lagr angian PDF Transp ort Simula tions .....................................1789 19.6.3. Running Lagr angian PDF Transp ort Simula tions with C onjuga te Heat Transf er.............1789 19.7. Postpr ocessing f or Lagr angian PDF Transp ort Calcula tions ...................................................1789 19.7.1. Reporting Options ......................................................................................................1789 19.7.2. Particle Tracking Options ............................................................................................1790 19.8. Postpr ocessing f or Euler ian PDF Transp ort Calcula tions ........................................................1791 19.8.1. Reporting Options ......................................................................................................1791 20. Using C hemistr y Acceler ation ...................................................................................................1793 20.1. Using ISA T...........................................................................................................................1794 20.1.1. ISAT Paramet ers..........................................................................................................1794 20.1.2. Monit oring ISA T..........................................................................................................1795 xliiiRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide20.1.3. Using ISA T Efficien tly..................................................................................................1796 20.1.4. Reading and Writing ISA T Tables .................................................................................1796 20.2. Using D ynamic M echanism R educ tion .................................................................................1797 20.2.1. Mechanism R educ tion P aramet ers..............................................................................1798 20.2.2. Monit oring and P ostpr ocessing D ynamic M echanism R educ tion .................................1800 20.2.3. Using D ynamic M echanism R educ tion E ffectively........................................................1801 20.3. Using C hemistr y Agglomer ation ..........................................................................................1802 20.4. Dimension R educ tion ..........................................................................................................1802 20.5. Using D ynamic C ell C lustering.............................................................................................1803 20.6. Using D ynamic A daptiv e Chemistr y with ANSY S Fluen t CHEMKIN-CFD S olver.......................1804 21. Modeling E ngine Ignition .........................................................................................................1807 21.1. Spark Model........................................................................................................................1807 21.1.1. Using the S park Model................................................................................................1807 21.1.2. Using the ECFM S park Model......................................................................................1810 21.2. Autoignition M odels ...........................................................................................................1811 21.2.1. Using the A utoignition M odels ...................................................................................1811 21.3. Crevice Model.....................................................................................................................1814 21.3.1. Using the C revice Model.............................................................................................1814 21.3.2. Crevice Model S olution D etails ....................................................................................1817 21.3.3. Postpr ocessing f or the C revice Model..........................................................................1817 21.3.3.1. Using the C revice Output F ile.............................................................................1819 22. Modeling P ollutan t Formation ..................................................................................................1823 22.1. NOx Formation ....................................................................................................................1823 22.1.1. Using the NO x Model..................................................................................................1823 22.1.1.1. Decoupled A naly sis: Overview ............................................................................1823 22.1.1.2. Enabling the NO x Models ...................................................................................1824 22.1.1.3. Defining the F uel S treams ..................................................................................1826 22.1.1.4. Specifying a U ser-D efined F unction f or the NO x Rate..........................................1828 22.1.1.5. Setting Thermal NO x Paramet ers........................................................................1829 22.1.1.6. Setting P rompt NO x Paramet ers.........................................................................1829 22.1.1.7. Setting F uel NO x Paramet ers..............................................................................1830 22.1.1.7.1. Setting G aseous and Liquid F uel NO x Paramet ers.......................................1830 22.1.1.7.2. Setting S olid (C oal) F uel NO x Paramet ers...................................................1831 22.1.1.8. Setting N2O P athw ay Paramet ers.......................................................................1832 22.1.1.9. Setting P aramet ers f or NO x Rebur n....................................................................1833 22.1.1.10. Setting SNCR P aramet ers..................................................................................1834 22.1.1.11. Setting Turbulenc e Paramet ers.........................................................................1836 22.1.1.12. Defining B oundar y Conditions f or the NO x Model............................................1838 22.1.2. Solution S trategies .....................................................................................................1838 22.1.3. Postpr ocessing ...........................................................................................................1839 22.2. SOx Formation ....................................................................................................................1840 22.2.1. Using the SO x Model..................................................................................................1840 22.2.1.1. Enabling the SO x Model.....................................................................................1841 22.2.1.2. Defining the F uel S treams ..................................................................................1842 22.2.1.3. Defining the SO x Fuel S tream S ettings ................................................................1844 22.2.1.3.1. Setting SO x Paramet ers f or G aseous and Liquid F uel Types.........................1845 22.2.1.3.2. Setting SO x Paramet ers f or a S olid F uel......................................................1846 22.2.1.4. Defining the SO x Formation M odel P aramet ers...................................................1848 22.2.1.5. Setting Turbulenc e Paramet ers...........................................................................1848 22.2.1.6. Specifying a U ser-D efined F unction f or the SO x Rate...........................................1851 22.2.1.7. Defining B oundar y Conditions f or the SO x Model...............................................1851 22.2.2. Solution S trategies .....................................................................................................1852 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. xlivUser's G uide22.2.3. Postpr ocessing ...........................................................................................................1853 22.3. Soot Formation ...................................................................................................................1854 22.3.1. Using the S oot M odels ................................................................................................1854 22.3.1.1. Setting U p the One-S tep M odel..........................................................................1855 22.3.1.2. Setting U p the Two-Step M odel..........................................................................1857 22.3.1.3. Setting U p the M oss-B rookes M odel and the Hall Ex tension ................................1860 22.3.1.3.1. Specifying a U ser-D efined F unction f or the S oot O xida tion R ate.................1863 22.3.1.3.2. Specifying a U ser-D efined F unction f or the S oot Precursor C oncentration ....1863 22.3.1.3.3. Species D efinition f or the M oss-B rookes M odel with a U ser-D efined P recursor Correlation ...............................................................................................................1864 22.3.1.4. Setting U p the M etho d of M omen ts Soot M odel.................................................1866 22.3.1.5. Defining B oundar y Conditions f or the S oot M odel..............................................1872 22.3.1.6. Reporting S oot Q uantities ..................................................................................1872 22.4. Using the D ecoupled D etailed C hemistr y Model..................................................................1873 23. Predic ting A erodynamic ally G ener ated N oise ..........................................................................1875 23.1. Overview ............................................................................................................................1875 23.1.1. Direct Metho d............................................................................................................1875 23.1.2. Integral M etho d by Ffowcs Williams and Ha wkings ......................................................1876 23.1.3. Metho d Based on Wave Equa tion ................................................................................1876 23.1.4. Broadband N oise S ource Models .................................................................................1877 23.2. Using the Ff owcs Williams and Ha wkings A coustics M odel...................................................1877 23.2.1. Enabling the FW-H A coustics M odel............................................................................1879 23.2.1.1. Setting M odel C onstan ts....................................................................................1880 23.2.1.2. Computing S ound “on the F ly”...........................................................................1881 23.2.1.3. Writing S ource Data Files....................................................................................1882 23.2.1.3.1. Exp orting S ource Data Without Enabling the FW-H M odel: Using the ANSY S Fluen t ASD F ormat....................................................................................................1883 23.2.1.3.2. Exp orting S ource Data Without Enabling the FW-H M odel: Using the C GNS Format.....................................................................................................................1883 23.2.2. Specifying S ource Sur faces.........................................................................................1884 23.2.2.1. Saving S ource Data............................................................................................1887 23.2.3. Specifying A coustic R eceivers.....................................................................................1887 23.2.4. Specifying the Time S tep............................................................................................1889 23.2.5. Postpr ocessing the FW-H A coustics M odel D ata..........................................................1891 23.2.5.1. Writing A coustic S ignals .....................................................................................1891 23.2.5.2. Reading U nsteady Acoustic S ource Data.............................................................1891 23.2.5.2.1. Pruning the S ignal D ata A utoma tically .......................................................1893 23.2.5.3. Reporting the S tatic P ressur e Time D erivative.....................................................1894 23.2.5.4. Using the FFT C apabilities f or S ound P ressur e Signals .........................................1894 23.2.6. FFT of A coustic S ources: Band A naly sis and Exp ort of Sur face Pressur e Spectra............1894 23.2.6.1. Using the FFT of A coustic S ources......................................................................1895 23.3. Using the A coustics Wave Equa tion M odel...........................................................................1902 23.3.1. Specifying S ource Mask and S ponge R egions ..............................................................1903 23.3.2. Solution C ontrols f or the A coustics Wave Equa tion ......................................................1905 23.3.3. Solution Initializa tion ..................................................................................................1907 23.3.4. Post-P rocessing ..........................................................................................................1908 23.4. Using the B roadband N oise S ource Models ..........................................................................1908 23.4.1. Enabling the B roadband N oise S ource Models ............................................................1909 23.4.1.1. Setting M odel C onstan ts....................................................................................1909 23.4.2. Postpr ocessing the B roadband N oise S ource Model D ata............................................1910 24. Modeling D iscr ete Phase ...........................................................................................................1911 24.1. Introduction ........................................................................................................................1911 xlvRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide24.1.1. Concepts ....................................................................................................................1912 24.1.1.1. Uncoupled v s. Coupled DPM ..............................................................................1912 24.1.1.2. Steady vs. Unsteady Tracking..............................................................................1912 24.1.1.3. Parcels...............................................................................................................1913 24.1.2. Limita tions .................................................................................................................1914 24.1.2.1. Limita tion on the P article Volume F raction ..........................................................1914 24.1.2.2. Limita tion on M odeling C ontinuous Susp ensions of P articles ..............................1914 24.1.2.3. Limita tions on M odeling P article R otation ..........................................................1914 24.1.2.4. Limita tions on U sing the D iscrete Phase M odel with O ther ANSY S Fluen t Models .1915 24.1.2.5. Limita tions on U sing the H ybrid Parallel M etho d................................................1916 24.1.2.6. Limita tions on U sing the Lagr angian Wall F ilm M odel.........................................1916 24.2. Steps f or U sing the D iscrete Phase M odels ...........................................................................1917 24.2.1. Options f or In teraction with the C ontinuous P hase ......................................................1918 24.2.2. Steady/Transien t Treatmen t of P articles .......................................................................1918 24.2.3. Tracking P aramet ers f or the D iscrete Phase M odel.......................................................1923 24.2.4. Drag La ws..................................................................................................................1925 24.2.5. Physical M odels f or the D iscrete Phase M odel..............................................................1925 24.2.5.1. Including R adia tion H eat Transf er Effects on the P articles ....................................1926 24.2.5.2. Including Thermophor etic F orce Effects on the P articles .....................................1927 24.2.5.3. Including S affman Lif t Force Effects on the P articles ............................................1927 24.2.5.4. Including the Virtual M ass F orce and P ressur e Gradien t Effects on P articles .........1927 24.2.5.5. Monit oring E rosion/A ccretion of P articles a t Walls...............................................1927 24.2.5.6. Pressur e Options f or Vaporization M odels ...........................................................1927 24.2.5.7. Enabling P ressur e Dependen t Boiling .................................................................1928 24.2.5.8. Including the E ffect of D roplet Temp erature on La tent Heat................................1929 24.2.5.9. Including the E ffect of P articles on Turbulen t Quantities .....................................1929 24.2.5.10. Including C ollision and D roplet C oalesc ence.....................................................1929 24.2.5.11. Including the DEM C ollision M odel...................................................................1929 24.2.5.12. Including D roplet B reakup...............................................................................1929 24.2.5.13. Modeling C ollision U sing the DEM M odel.........................................................1930 24.2.5.13.1. Limita tions ..............................................................................................1934 24.2.5.13.2. Numer ic Recommenda tions ....................................................................1935 24.2.6. User-D efined F unctions ..............................................................................................1935 24.2.7. Numer ics of the D iscrete Phase M odel........................................................................1937 24.2.7.1. Numer ics f or Tracking of the P articles .................................................................1939 24.2.7.2. Including C oupled H eat-Mass S olution E ffects on the P articles ............................1940 24.2.7.3. Tracking in a R eference Frame ............................................................................1940 24.2.7.4. Node B ased A veraging of P article D ata...............................................................1941 24.2.7.5. Linear ized S ource Terms.....................................................................................1942 24.2.7.6. Stagger ing of P articles in S pace and Time ...........................................................1942 24.2.7.7. Under-R elaxing Lagr angian Wall F ilm H eigh t......................................................1943 24.3. Setting Initial C onditions f or the D iscrete Phase ...................................................................1943 24.3.1. Injec tion Types...........................................................................................................1944 24.3.2. Particle Types.............................................................................................................1947 24.3.3. Point Properties f or S ingle Injec tions ...........................................................................1948 24.3.4. Point Properties f or G roup Injec tions ...........................................................................1949 24.3.5. Point Properties f or C one Injec tions ............................................................................1950 24.3.6. Point Properties f or Sur face Injec tions .........................................................................1953 24.3.6.1. Using the R osin-R ammler D iamet er D istribution M etho d....................................1954 24.3.7. Point Properties f or P lain-Or ifice Atomiz er Injec tions ...................................................1955 24.3.8. Point Properties f or P ressur e-Swirl Atomiz er Injec tions ................................................1956 24.3.9. Point Properties f or A ir-Blast/A ir-Assist A tomiz er Injec tions ..........................................1957 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. xlviUser's G uide24.3.10. Point Properties f or Flat-Fan A tomiz er Injec tions ........................................................1958 24.3.11. Point Properties f or E ffervescent Atomiz er Injec tions .................................................1960 24.3.12. Point Properties f or File Injec tions .............................................................................1960 24.3.12.1. Steady File F ormat...........................................................................................1961 24.3.12.2. Unsteady File F ormat.......................................................................................1961 24.3.12.3. User Input f or File Injec tions .............................................................................1962 24.3.13. Point Properties f or C ondensa te Injec tions ................................................................1963 24.3.14. Using the R osin-R ammler D iamet er D istribution M etho d...........................................1963 24.3.14.1. The S tochastic R osin-R ammler D iamet er D istribution M etho d...........................1966 24.3.15. Creating and M odifying Injec tions ............................................................................1966 24.3.15.1. Creating Injec tions ...........................................................................................1968 24.3.15.2. Modifying Injec tions ........................................................................................1968 24.3.15.3. Copying Injec tions ...........................................................................................1968 24.3.15.4. Deleting Injec tions ...........................................................................................1968 24.3.15.5. Listing Injec tions ..............................................................................................1968 24.3.15.6. Reading and Writing Injec tions .........................................................................1968 24.3.16. Defining Injec tion P roperties ....................................................................................1969 24.3.17. Specifying Injec tion-S pecific P hysical M odels ............................................................1973 24.3.17.1. Drag La ws........................................................................................................1973 24.3.17.2. Particle R otation ..............................................................................................1974 24.3.17.3. Rough Wall M odel............................................................................................1975 24.3.17.4. Brownian M otion E ffects..................................................................................1975 24.3.17.5. Breakup...........................................................................................................1975 24.3.18. Specifying Turbulen t Dispersion of P articles ..............................................................1978 24.3.18.1. Stochastic Tracking ..........................................................................................1978 24.3.18.2. Cloud Tracking.................................................................................................1980 24.3.19. Custom P article La ws................................................................................................1980 24.3.20. Defining P roperties C ommon t o More than One Injec tion ..........................................1981 24.3.20.1. Modifying P roperties ........................................................................................1982 24.3.20.2. Modifying P roperties C ommon t o a Subset of S elec ted Injec tions .....................1984 24.3.21. Point Properties f or Transien t Injec tions ....................................................................1984 24.4. Setting B oundar y Conditions f or the D iscrete Phase .............................................................1985 24.4.1. Discrete Phase B oundar y Condition Types...................................................................1986 24.4.1.1. The reflec t Boundar y Condition .........................................................................1987 24.4.1.2. The trap Boundar y Condition .............................................................................1987 24.4.1.3. The escape Boundar y Condition ........................................................................1988 24.4.1.4. The wall-jet Boundar y Condition .......................................................................1988 24.4.1.5. The wall-film Boundar y Condition .....................................................................1988 24.4.1.6. The interior Boundar y Condition .......................................................................1991 24.4.1.7. The user-defined Boundar y Condition ...............................................................1991 24.4.2. Default D iscrete Phase B oundar y Conditions ...............................................................1991 24.4.3. Coefficien ts of R estitution ...........................................................................................1991 24.4.4. Friction C oefficien t.....................................................................................................1991 24.4.5. Particle-W all Impingemen t Heat Transf er.....................................................................1992 24.4.6. Film C ondensa tion M odel...........................................................................................1994 24.4.7. Wall B oundar y La yer M odel.........................................................................................1996 24.4.8. Setting P article E rosion and A ccretion P aramet ers.......................................................1996 24.5. Particle E rosion C oupled with D ynamic M eshes ...................................................................2001 24.5.1. Preliminar ies..............................................................................................................2001 24.5.2. Procedur e for the E rosion C oupled with D ynamic M esh S etup and S olution .................2002 24.5.3. Postpr ocessing f or E rosion D ynamic M esh C alcula tions ...............................................2008 24.6. Setting M aterial P roperties f or the D iscrete Phase ................................................................2008 xlviiRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide24.6.1. Summar y of P roperty Inputs .......................................................................................2008 24.6.2. Setting D iscrete-Phase P hysical Properties ..................................................................2011 24.6.2.1. The C oncept of D iscrete-Phase M aterials ............................................................2011 24.6.2.1.1. Defining A dditional D iscrete-Phase M aterials.............................................2013 24.6.2.2. Descr iption of the P roperties ..............................................................................2013 24.7. Solution S trategies f or the D iscrete Phase ............................................................................2022 24.7.1. Performing Trajec tory Calcula tions ..............................................................................2022 24.7.1.1. Uncoupled C alcula tions .....................................................................................2023 24.7.1.2. Coupled C alcula tions .........................................................................................2023 24.7.1.2.1. Procedur es for a C oupled Two-Phase F low.................................................2024 24.7.1.2.2. Stochastic Tracking in C oupled C alcula tions ...............................................2025 24.7.1.2.3. Under-R elaxa tion of the In terphase Ex change Terms..................................2025 24.7.2. Resetting the In terphase Ex change Terms...................................................................2027 24.8. Postpr ocessing f or the D iscrete Phase ..................................................................................2027 24.8.1. Displa ying of Trajec tories............................................................................................2028 24.8.1.1. Options f or P article Trajec tory Plots ....................................................................2030 24.8.1.2. Controlling the P article Tracking S tyle.................................................................2031 24.8.1.3. Controlling the Vector Style of P article Tracks ......................................................2033 24.8.1.4. Imp orting P article D ata......................................................................................2037 24.8.1.5. Particle F iltering.................................................................................................2038 24.8.1.6. Graphic al D ispla y for A xisymmetr ic Geometr ies..................................................2038 24.8.2. Reporting of Trajec tory Fates......................................................................................2039 24.8.2.1. Trajec tory Fates..................................................................................................2039 24.8.2.2. Summar y Reports..............................................................................................2040 24.8.2.2.1. Elapsed Time .............................................................................................2041 24.8.2.2.2. Mass Transf er Summar y.............................................................................2041 24.8.2.2.3. Ener gy Transf er Summar y..........................................................................2042 24.8.2.2.4. Heat Rate and Ener gy Reporting ................................................................2042 24.8.2.2.4.1. Change of H eat and C hange of Ener gy Reporting ..............................2044 24.8.2.2.5. Combusting P articles ................................................................................2045 24.8.2.2.6. Combusting P articles with the M ultiple Sur face Reaction M odel.................2045 24.8.2.2.7. Multic omp onen t Particles .........................................................................2045 24.8.3. Step-b y-Step R eporting of Trajec tories........................................................................2046 24.8.4. Reporting of C urrent Positions f or U nsteady Tracking..................................................2048 24.8.5. Reporting of In terphase Ex change Terms (D iscrete Phase S ources)...............................2049 24.8.6. Reporting of D iscrete Phase Variables .........................................................................2050 24.8.6.1. Note on the C ell-A veraging of P article Variables ..................................................2052 24.8.7. Reporting of U nsteady DPM S tatistics .........................................................................2052 24.8.8. Sampling of Trajec tories..............................................................................................2054 24.8.9. Hist ogram R eporting of S amples ................................................................................2056 24.8.9.1. Analy sis, Investiga tion, and R eporting of S amples ...............................................2057 24.8.9.2. Data R educ tion of S amples ................................................................................2059 24.8.10. Summar y Reporting of C urrent Particles ....................................................................2061 24.8.11. Postpr ocessing of E rosion/A ccretion R ates................................................................2063 24.8.12. Assessing the R isk f or Solids D eposit F ormation D uring S elec tive Catalytic R educ tion Process.................................................................................................................................2063 24.9. Parallel P rocessing f or the D iscrete Phase M odel..................................................................2066 25. Modeling M acroscopic P articles ...............................................................................................2071 25.1. Overview and Limita tions ....................................................................................................2071 25.2. Loading the MPM add-on M odule .......................................................................................2072 25.3. Setting up MPM M odel S imula tions .....................................................................................2072 25.4. Modeling M acroscopic P articles ..........................................................................................2073 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. xlviiiUser's G uide25.4.1. Specifying P article Tracking P aramet ers.......................................................................2074 25.4.2. Specifying the D rag La w.............................................................................................2075 25.4.3. Defining P aramet ers f or P article-P article and P article-W all C ollisions ............................2077 25.4.4. Specifying D eposition P aramet ers...............................................................................2078 25.4.5. Specifying Injec tion P aramet ers..................................................................................2079 25.4.5.1. Defining MPM Injec tion P roperties .....................................................................2080 25.4.5.2. Inputs f or point Injec tions ...............................................................................2082 25.4.5.3. Inputs f or plane Injec tions ...............................................................................2084 25.4.5.4. Inputs f or packing Injec tions ...........................................................................2086 25.4.5.5. Inputs f or from-file Injec tions .......................................................................2087 25.4.6. Defining F ield F orces..................................................................................................2087 25.4.7. Initializing the MPM mo del.........................................................................................2088 26. Modeling M ultiphase F lows......................................................................................................2091 26.1. Introduction ........................................................................................................................2091 26.2. Steps f or U sing a M ultiphase M odel.....................................................................................2091 26.2.1. Enabling the M ultiphase M odel..................................................................................2093 26.2.2. Choosing Volume F raction F ormula tion ......................................................................2097 26.2.2.1. Interface Modeling Type.....................................................................................2097 26.2.2.2. Spatial D iscretiza tion Schemes f or Volume F raction ............................................2099 26.2.2.3. Volume F raction Limits .......................................................................................2100 26.2.2.4. Exp ert Options ...................................................................................................2100 26.2.3. Solving a H omo geneous M ultiphase F low...................................................................2101 26.2.4. The B oussinesq A pproxima tion in M ultiphase F low.....................................................2101 26.2.5. Modeling C ompr essible F lows....................................................................................2102 26.2.6. Defining the P hases ....................................................................................................2103 26.2.7. Including B ody Forces.................................................................................................2104 26.2.8. Modeling M ultiphase S pecies Transp ort......................................................................2104 26.2.9. Specifying H eterogeneous R eactions ..........................................................................2106 26.2.10. Including M ass Transf er Effects..................................................................................2109 26.2.10.1. Alternative Modeling of Ener gy Sources...........................................................2111 26.2.10.2. Mass Transf er M echanisms ...............................................................................2113 26.2.10.2.1. Constan t-Rate Option ..............................................................................2114 26.2.10.2.2. User-D efined Option ...............................................................................2114 26.2.10.2.3. Popula tion-B alanc e Mechanism ...............................................................2114 26.2.10.2.4. Cavitation M echanism .............................................................................2114 26.2.10.2.5. Evaporation-C ondensa tion M echanism ....................................................2118 26.2.10.2.6. Species-M ass-T ransf er M echanism ...........................................................2120 26.2.10.2.7. Boiling M echanism ..................................................................................2124 26.2.11. Defining M ultiphase C ell Z one and B oundar y Conditions ..........................................2124 26.2.11.1. Steps f or S etting B oundar y Conditions .............................................................2124 26.2.11.2. Steps f or S etting C ell Z one C onditions ..............................................................2131 26.2.11.3. Boundar y and C ell Z one C onditions f or the M ixture and the Individual P hases ...2132 26.2.11.3.1. VOF M odel..............................................................................................2132 26.2.11.3.2. Mixture Model.........................................................................................2133 26.2.11.3.3. Euler ian M odel........................................................................................2135 26.2.11.4. Steps f or C opying C ell Z one and B oundar y Conditions ......................................2140 26.2.12. Setting Initial Volume F ractions .................................................................................2141 26.2.12.1. Options f or P atching Volume F raction ...............................................................2141 26.3. Setting U p the VOF M odel...................................................................................................2142 26.3.1. Solving S teady-State VOF P roblems .............................................................................2143 26.3.2. Guidelines f or U sing the M ultiphase P seudo Transien t Solver.......................................2143 26.3.3. Including C oupled L evel Set with the VOF M odel.........................................................2143 xlixRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide26.3.4. Modeling Op en C hannel F lows...................................................................................2144 26.3.4.1. Defining Inlet G roups .........................................................................................2146 26.3.4.2. Defining Outlet G roups ......................................................................................2146 26.3.4.3. Setting the Inlet G roup .......................................................................................2146 26.3.4.4. Setting the Outlet G roup ....................................................................................2147 26.3.4.5. Determining the F ree Sur face Level....................................................................2147 26.3.4.6. Determining the B ottom L evel...........................................................................2148 26.3.4.7. Specifying the Total H eigh t................................................................................2149 26.3.4.8. Determining the Velocity Magnitude ..................................................................2149 26.3.4.9. Determining the S econdar y Phase f or the Inlet ...................................................2149 26.3.4.10. Determining the S econdar y Phase f or the Outlet ..............................................2150 26.3.4.11. Choosing the P ressur e Specific ation M etho d....................................................2150 26.3.4.12. Choosing the D ensit y Interpolation M etho d.....................................................2151 26.3.4.13. Open C hannel F low Compa tibilit y with Velocity Inlet ........................................2152 26.3.4.13.1. Velocity Inlet , Open C hannel F low, Steady-State........................................2152 26.3.4.13.2. Velocity Inlet , Open C hannel F low,Transien t.............................................2152 26.3.4.14. Limita tions .......................................................................................................2153 26.3.4.15. Recommenda tions f or S etting U p an Op en C hannel F low Problem ....................2153 26.3.5. Modeling Op en C hannel Wave Boundar y Conditions ...................................................2154 26.3.5.1. Summar y Report and R egime C heck ..................................................................2162 26.3.5.2. Transien t Profile Supp ort for Wave Inputs ...........................................................2163 26.3.5.3. Alternative Stokes Wave Theor y Variant..............................................................2164 26.3.6. Recommenda tions f or Op en C hannel Initializa tion ......................................................2164 26.3.6.1. Reporting P aramet ers f or Op en C hannel Wave BC Option ...................................2167 26.3.7. Numer ical Beach Treatmen t for Op en C hannels ...........................................................2167 26.3.7.1. Solution S trategies .............................................................................................2170 26.3.8. Defining the P hases f or the VOF M odel.......................................................................2171 26.3.8.1. Defining the P rimar y Phase ................................................................................2171 26.3.8.2. Defining a S econdar y Phase ...............................................................................2172 26.3.8.3. Including Sur face Tension and A dhesion E ffects..................................................2173 26.3.8.4. Discretizing U sing the P hase L ocalized C ompr essiv e Scheme ..............................2176 26.3.9. Setting Time-D ependen t Paramet ers f or the Explicit Volume F raction F ormula tion .......2179 26.3.10. Modeling S olidific ation/M elting ................................................................................2181 26.3.11. Using the VOF-t o-DPM M odel Transition f or D ispersion of Liquid in G as.....................2181 26.3.11.1. Limita tions on U sing the VOF-t o-DPM M odel Transition ....................................2182 26.3.11.2. Setting up the VOF-t o-DPM M odel Transition ....................................................2183 26.3.11.3. Postpr ocessing f or VOF-t o-DPM M odel Transition C alcula tions ..........................2188 26.4. Setting U p the M ixture Model.............................................................................................2189 26.4.1. Defining the P hases f or the M ixture Model..................................................................2189 26.4.1.1. Defining the P rimar y Phase ................................................................................2189 26.4.1.2. Defining a N on-G ranular S econdar y Phase .........................................................2189 26.4.1.3. Defining a G ranular S econdar y Phase .................................................................2190 26.4.1.4. Defining the In terfacial A rea C oncentration via the Transp ort Equa tion ...............2193 26.4.1.5. Defining the A lgebr aic In terfacial A rea C oncentration .........................................2196 26.4.1.6. Defining D rag B etween P hases ...........................................................................2197 26.4.1.7. Defining the S lip Velocity...................................................................................2197 26.4.1.8. Including Sur face Tension and Wall A dhesion E ffects..........................................2198 26.4.2. Including M ixture Drift Force......................................................................................2198 26.4.3. Including C avitation E ffects........................................................................................2199 26.4.4. Including S emi-M echanistic B oiling ............................................................................2199 26.4.4.1. Overview and Limita tions f or the S emi-M echanistic B oiling M odel......................2199 26.4.4.2. Using the S emi-M echanistic B oiling M odel.........................................................2200 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. lUser's G uide26.4.4.3. Cell Z one S pecific B oiling ...................................................................................2204 26.4.4.4. Exp ert Options f or the S emi-M echanistic B oiling M odel......................................2204 26.4.4.5. Solution S trategies f or the S emi-M echanistic B oiling M odel................................2207 26.5. Setting U p the E uler ian M odel.............................................................................................2208 26.5.1. Additional G uidelines f or E uler ian M ultiphase S imula tions ..........................................2208 26.5.2. Defining the P hases f or the E uler ian M odel.................................................................2209 26.5.2.1. Defining the P rimar y Phase ................................................................................2209 26.5.2.2. Defining a N on-G ranular S econdar y Phase .........................................................2209 26.5.2.3. Defining a G ranular S econdar y Phase .................................................................2210 26.5.2.4. Defining the In terfacial A rea C oncentration ........................................................2214 26.5.2.5. Defining the In teraction B etween P hases ...........................................................2216 26.5.2.5.1. Specifying the D rag F unction ....................................................................2216 26.5.2.5.1.1. Drag M odific ation .............................................................................2219 26.5.2.5.2. Specifying the R estitution C oefficien ts (G ranular F low Only) .......................2220 26.5.2.5.3. Including the Lif t Force..............................................................................2220 26.5.2.5.4. Including the Wall L ubrication F orce..........................................................2221 26.5.2.5.5. Including the Turbulen t Dispersion F orce...................................................2224 26.5.2.5.6. Including Sur face Tension and Wall A dhesion E ffects..................................2227 26.5.2.5.7. Including the Virtual M ass F orce................................................................2228 26.5.3. Modeling Turbulenc e..................................................................................................2229 26.5.3.1. Including Turbulenc e Interaction S ource Terms...................................................2231 26.5.3.2. Customizing the k- ε Multiphase Turbulen t Viscosity...........................................2233 26.5.4. Including H eat Transf er Effects....................................................................................2233 26.5.5. Using an A lgebr aic In terfacial A rea M odel...................................................................2235 26.5.6. Including the D ense D iscrete Phase M odel..................................................................2236 26.5.6.1. Defining a G ranular D iscrete Phase .....................................................................2240 26.5.7. Including the B oiling M odel........................................................................................2241 26.5.8. Including the M ulti-F luid VOF M odel...........................................................................2249 26.6. Setting U p the Wet Steam M odel.........................................................................................2252 26.6.1. Using U ser-D efined Thermodynamic Wet Steam P roperties .........................................2252 26.6.2. Writing the U ser-D efined Wet Steam P roperty Functions (UD WSPF) .............................2253 26.6.3. Compiling Your UD WSPF and B uilding a S hared Libr ary File.........................................2255 26.6.4. Loading the UD WSPF S hared Libr ary File.....................................................................2257 26.6.5. UDWSPF Example .......................................................................................................2257 26.7. Solution S trategies f or M ultiphase M odeling ........................................................................2261 26.7.1. Coupled S olution f or E uler ian M ultiphase F lows..........................................................2262 26.7.2. Coupled S olution f or VOF and M ixture Multiphase F lows.............................................2263 26.7.3. Selec ting the P ressur e-Velocity Coupling M etho d........................................................2264 26.7.3.1. Limita tions and R ecommenda tions of the C oupled with Volume F raction Options for the VOF and M ixture Models ......................................................................................2266 26.7.3.2. Solving N-P hase Volume F raction E qua tions .......................................................2267 26.7.4. Controlling the Volume F raction C oupled S olution ......................................................2267 26.7.5. VOF M odel.................................................................................................................2270 26.7.5.1. Setting the R eference Pressur e Location .............................................................2270 26.7.5.2. Pressur e Interpolation Scheme ...........................................................................2271 26.7.5.3. Discretiza tion Scheme S elec tion .........................................................................2271 26.7.5.4. High-Or der R hie-C how Face Flux In terpolation ...................................................2272 26.7.5.5. Treatmen t of U nsteady Terms in R hie-C how Face Flux In terpolation ....................2272 26.7.5.6. Using U nstr uctured Variant of PREST O Pressur e Scheme .....................................2273 26.7.5.7. Pressur e-Velocity Coupling and U nder-R elaxa tion f or the Time-dep enden t Formula- tions ...............................................................................................................................2273 26.7.5.8. Under-R elaxa tion f or the S teady-State Formula tion ............................................2273 liRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide26.7.6. Mixture Model............................................................................................................2274 26.7.6.1. Setting the U nder-R elaxa tion F actor for the S lip Velocity.....................................2274 26.7.6.2. Calcula ting an Initial S olution .............................................................................2274 26.7.7. Euler ian M odel...........................................................................................................2274 26.7.7.1. Calcula ting an Initial S olution .............................................................................2274 26.7.7.2. Temp orarily Ignor ing Lif t and Virtual M ass F orces...............................................2275 26.7.7.3. Using W-C ycle M ultigr id.....................................................................................2275 26.7.7.4. Including the A nisotr opic D rag La w....................................................................2275 26.7.7.5. Controlling NIT A Solution Options via the Text Interface......................................2275 26.7.8. Wet Steam M odel.......................................................................................................2276 26.7.8.1. Boundar y Conditions , Initializa tion, and P atching ................................................2276 26.7.8.2. Solution Limits f or the Wet Steam M odel............................................................2277 26.7.8.3. Solution S trategies f or the Wet Steam M odel......................................................2277 26.8. Multiphase C ase C heck ........................................................................................................2278 26.9. Postpr ocessing f or M ultiphase M odeling .............................................................................2278 26.9.1. Model-S pecific Variables .............................................................................................2279 26.9.1.1. VOF M odel.........................................................................................................2279 26.9.1.2. Mixture Model...................................................................................................2279 26.9.1.3. Euler ian M odel...................................................................................................2279 26.9.1.4. Multiphase S pecies Transp ort.............................................................................2281 26.9.1.5. Wet Steam M odel...............................................................................................2281 26.9.1.6. Dense D iscrete Phase M odel..............................................................................2282 26.9.2. Displa ying Velocity Vectors.........................................................................................2282 26.9.3. Reporting F luxes........................................................................................................2283 26.9.4. Reporting F orces on Walls...........................................................................................2284 26.9.5. Reporting F low Rates..................................................................................................2284 27. Popula tion B alanc e M odel ........................................................................................................2285 27.1. Popula tion B alanc e Module Installa tion ...............................................................................2285 27.2. Loading the P opula tion B alanc e Module ..............................................................................2285 27.3. Popula tion B alanc e Model S etup .........................................................................................2286 27.3.1. Enabling the P opula tion B alanc e Model......................................................................2286 27.3.1.1. Gener ated DQMOM Values .................................................................................2295 27.3.2. Defining P opula tion B alanc e Boundar y Conditions ......................................................2299 27.3.2.1. Initializing B in Fractions With a L og-Normal D istribution .....................................2301 27.3.3. Specifying P opula tion B alanc e Solution C ontrols.........................................................2302 27.3.4. Coupling With F luid D ynamics ....................................................................................2302 27.3.5. Specifying In terphase M ass Transf er D ue t o Nuclea tion and G rowth ............................2303 27.4. Postpr ocessing f or the P opula tion B alanc e Model................................................................2307 27.4.1. Popula tion B alanc e Solution Variables .........................................................................2307 27.4.2. Reporting D erived P opula tion B alanc e Variables .........................................................2307 27.4.2.1. Computing M omen ts.........................................................................................2308 27.4.2.2. Displa ying a N umb er D ensit y Function ...............................................................2308 27.5. UDFs f or P opula tion B alanc e Modeling ................................................................................2310 27.5.1. Popula tion B alanc e Variables ......................................................................................2310 27.5.2. Popula tion B alanc e DEFINE Macros...........................................................................2311 27.5.2.1.DEFINE_PB_BREAK_UP_RATE_FREQ ...........................................................2311 27.5.2.1.1. Usage .......................................................................................................2311 27.5.2.1.2. Example ....................................................................................................2311 27.5.2.2.DEFINE_PB_BREAK_UP_RATE_PDF .............................................................2312 27.5.2.2.1. Usage .......................................................................................................2312 27.5.2.2.2. Example ....................................................................................................2312 27.5.2.3.DEFINE_PB_COALESCENCE_RATE ...............................................................2313 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. liiUser's G uide27.5.2.3.1. Usage .......................................................................................................2313 27.5.2.3.2. Example ....................................................................................................2314 27.5.2.4.DEFINE_PB_NUCLEATION_RATE ..................................................................2314 27.5.2.4.1. Usage .......................................................................................................2314 27.5.2.4.2. Example ....................................................................................................2314 27.5.2.5.DEFINE_PB_GROWTH_RATE ..........................................................................2315 27.5.2.5.1. Usage .......................................................................................................2315 27.5.2.5.2. Example ....................................................................................................2316 27.5.3. Hooking a P opula tion B alanc e UDF t o ANSY S Fluen t...................................................2317 27.6.DEFINE_HET_RXN_RATE Macro.......................................................................................2317 27.6.1. Descr iption ................................................................................................................2317 27.6.2. Usage .........................................................................................................................2317 27.6.3. Example .....................................................................................................................2318 27.6.4. Hooking a H eterogeneous R eaction R ate UDF t o ANSY S Fluen t...................................2319 28. Modeling S olidific ation and M elting ........................................................................................2321 28.1. Setup P rocedur e.................................................................................................................2321 28.2. Procedur es for M odeling C ontinuous C asting ......................................................................2324 28.3. Modeling Thermal and S olutal B uoyancy.............................................................................2325 28.4. Solution P rocedur e..............................................................................................................2326 28.5. Postpr ocessing ....................................................................................................................2326 29. Modeling F luid-S tructure In teraction (FSI) Within F luen t........................................................2329 29.1. Overview and Limita tions ....................................................................................................2329 29.2. Setting U p an In trinsic F luid-S tructure Interaction (FSI) S imula tion .......................................2330 30. Modeling E uler ian Wall F ilms ....................................................................................................2337 30.1. Limita tions ..........................................................................................................................2337 30.2. Setting E uler ian Wall F ilm M odel Options .............................................................................2337 30.3. Setting E uler ian Wall F ilm S olution C ontrols.........................................................................2342 30.4. Setting E uler ian Wall F ilm B oundar y, Initial, and S ource Term C onditions ...............................2344 30.5. Postpr ocessing the E uler ian Wall F ilm..................................................................................2348 31. Modeling E lectric Potential F ield ..............................................................................................2351 31.1. Overview and Limita tions ....................................................................................................2351 31.2. Using the E lectric Potential M odel.......................................................................................2351 31.3. Postpr ocessing the E lectric Potential F ield ...........................................................................2353 32. Modeling B atteries....................................................................................................................2355 32.1. Introduction ........................................................................................................................2355 32.1.1. Overview ....................................................................................................................2355 32.1.2. Gener al Procedur e......................................................................................................2356 32.1.3. Installing the B attery Module ......................................................................................2356 32.2. Using the S ingle-P otential Empir ical Battery Model..............................................................2357 32.2.1. Geometr y Definition f or the S ingle-P otential Empir ical Battery Model..........................2357 32.2.2. Loading the S ingle-P otential Empir ical Battery Module ................................................2357 32.2.3. Getting S tarted With the S ingle-P otential Empir ical Battery Model...............................2358 32.2.3.1. Specifying S ingle-P otential Empir ical Battery Model P aramet ers.........................2360 32.2.3.2. Specifying S epar ator P aramet ers........................................................................2362 32.2.3.3. Specifying E lectric Field P aramet ers....................................................................2363 32.2.4. Solution C ontrols f or the S ingle-P otential Empir ical Battery Model...............................2363 32.2.5. Postpr ocessing the S ingle-P otential Empir ical Battery Model.......................................2364 32.2.6. User-A ccessible F unctions ...........................................................................................2366 32.2.6.1. Compiling the C ustomiz ed B attery Source Code.................................................2366 32.2.6.1.1. Compiling the C ustomiz ed S ource Code U nder Linux .................................2366 32.2.6.1.2. Compiling the C ustomiz ed S ource Code U nder Windo ws...........................2367 32.3. Using the D ual-P otential MSMD and C ell N etwork Battery Models ........................................2368 liiiRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide32.3.1. Limita tions .................................................................................................................2368 32.3.2. Geometr y Definition ...................................................................................................2369 32.3.3. Loading the D ual-P otential MSMD B attery Module ......................................................2369 32.3.4. Setting up the D ual-P otential MSMD B attery Model....................................................2370 32.3.4.1. Specifying B attery Model Options ......................................................................2371 32.3.4.2. Specifying B attery Model P aramet ers.................................................................2377 32.3.4.2.1. Inputs f or the NT GK Empir ical M odel..........................................................2378 32.3.4.2.2. Inputs f or the E quiv alen t Circuit M odel......................................................2382 32.3.4.2.3. Inputs f or the N ewman ’s P2D M odel..........................................................2384 32.3.4.2.4. Input f or the U ser-D efined E-M odel...........................................................2387 32.3.4.3. Specifying C onduc tive Zones .............................................................................2388 32.3.4.4. Specifying E lectric Contacts...............................................................................2389 32.3.4.5. Specifying A dvanced Option ..............................................................................2391 32.3.4.6. Specifying Ex ternal and In ternal S hort-Circuit R esistanc es...................................2395 32.3.5. Using P aramet er Estima tion Tools...............................................................................2396 32.3.6. Initializing the B attery Model......................................................................................2402 32.3.7. Modifying M aterial P roperties .....................................................................................2402 32.3.7.1. Specifying UDS D iffusivit y for the A ctive Material................................................2402 32.3.7.2. Specifying UDS D iffusivit y for the P assiv e Material..............................................2403 32.3.7.3. Defining D ifferent Materials f or P ositiv e and N egative Electrodes ........................2403 32.3.8. Solution C ontrols f or the D ual-P otential MSMD B attery Model.....................................2403 32.3.9. Postpr ocessing the D ual-P otential MSMD B attery Model.............................................2404 32.3.10. User-A ccessible F unctions .........................................................................................2405 32.3.10.1. Compiling the C ustomiz ed B attery Source Code...............................................2407 32.3.10.1.1. Compiling the C ustomiz ed S ource Code U nder Linux ...............................2407 32.3.10.1.2. Compiling the C ustomiz ed S ource Code U nder Windo ws.........................2408 33. Modeling F uel C ells ...................................................................................................................2409 33.1. Using the PEMFC M odel......................................................................................................2409 33.1.1. Overview and Limita tions ...........................................................................................2409 33.1.2. Geometr y Definition f or the PEMFC M odel..................................................................2410 33.1.3. Installing the PEMFC M odel........................................................................................2410 33.1.4. Loading the PEMFC M odule ........................................................................................2410 33.1.5. Workflow for U sing the PEMFC M odule .......................................................................2411 33.1.6. Setting U p the PEMFC M odule ....................................................................................2412 33.1.6.1. Specifying M odel Options ( ModelTab)...............................................................2413 33.1.6.2. Specifying M odel P aramet ers ( Paramet ersTab).................................................2417 33.1.6.3. Specifying A node P roperties ( AnodeTab)..........................................................2420 33.1.6.3.1. Specifying C urrent Collec tor P roperties f or the A node................................2420 33.1.6.3.2. Specifying F low Channel P roperties f or the A node.....................................2421 33.1.6.3.3. Specifying P orous E lectrode P roperties f or the A node................................2422 33.1.6.3.4. Specifying C atalyst La yer Properties f or the A node.....................................2423 33.1.6.3.5. Specifying M icro Porous La yer (Optional) P roperties f or the A node.............2425 33.1.6.3.6. Specifying C ell Z one C onditions f or the A node...........................................2426 33.1.6.4. Specifying E lectrolyte/M embr ane P roperties ( Electrolyt eTab)...........................2426 33.1.6.4.1. Specifying C ell Z one C onditions f or the M embr ane ....................................2428 33.1.6.5. Specifying C athode P roperties ( Catho deTab).....................................................2428 33.1.6.5.1. Specifying C urrent Collec tor P roperties f or the C athode.............................2428 33.1.6.5.2. Specifying F low Channel P roperties f or the C athode..................................2428 33.1.6.5.3. Specifying P orous E lectrode P roperties f or the C athode.............................2428 33.1.6.5.4. Specifying C atalyst La yer Properties f or the C athode..................................2429 33.1.6.5.5. Specifying M icro Porous La yer (Optional) P roperties f or the C athode..........2430 33.1.6.5.6. Specifying C ell Z one C onditions f or the C athode........................................2431 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. livUser's G uide33.1.6.6. Setting A dvanced P roperties ( Advanc edTab).....................................................2431 33.1.6.6.1. Setting C ontact Resistivities f or the PEMFC M odel......................................2431 33.1.6.6.2. Setting C oolan t Channel P roperties f or the PEMFC M odel (Optional) ..........2433 33.1.6.6.3. Managing S tacks f or the PEMFC M odel......................................................2434 33.1.6.7. Reporting on the S olution ( Rep ortsTab)............................................................2435 33.1.7. PEMFC M odel B oundar y Conditions ............................................................................2436 33.1.8. Solution G uidelines f or the PEMFC M odel....................................................................2437 33.1.9. Postpr ocessing the PEMFC M odel...............................................................................2437 33.1.10. User-A ccessible F unctions .........................................................................................2439 33.1.10.1. Compiling the C ustomiz ed PEMFC S ource Code...............................................2442 33.1.10.1.1. Compiling the C ustomiz ed S ource Code U nder Linux ...............................2442 33.1.10.1.2. Compiling the C ustomiz ed S ource Code under Windo ws.........................2443 33.2. Using the F uel C ell and E lectrolysis M odel............................................................................2444 33.2.1. Overview and Limita tions ...........................................................................................2444 33.2.2. Geometr y Definition f or the F uel C ell and E lectrolysis M odel.......................................2444 33.2.3. Installing the F uel C ell and E lectrolysis M odel..............................................................2445 33.2.4. Loading the F uel C ell and E lectrolysis M odule .............................................................2445 33.2.5. Workflow for U sing the F uel C ell and E lectrolysis M odule .............................................2445 33.2.6. Setting U p the F uel C ell and E lectrolysis M odule ..........................................................2446 33.2.6.1. Specifying M odel Options ( ModelTab)...............................................................2448 33.2.6.2. Specifying M odel P aramet ers ( Paramet ersTab).................................................2450 33.2.6.3. Specifying A node P roperties ( AnodeTab)..........................................................2451 33.2.6.3.1. Specifying C urrent Collec tor P roperties f or the A node................................2452 33.2.6.3.2. Specifying F low Channel P roperties f or the A node.....................................2453 33.2.6.3.3. Specifying P orous E lectrode P roperties f or the A node................................2453 33.2.6.3.4. Specifying C atalyst La yer Properties f or the A node.....................................2454 33.2.6.3.5. Specifying C ell Z one C onditions f or the A node...........................................2455 33.2.6.4. Specifying E lectrolyte/M embr ane P roperties ( Electrolyt eTab)...........................2455 33.2.6.4.1. Specifying C ell Z one C onditions f or the M embr ane ....................................2456 33.2.6.5. Specifying C athode P roperties ( Catho deTab).....................................................2456 33.2.6.5.1. Specifying C urrent Collec tor P roperties f or the C athode.............................2456 33.2.6.5.2. Specifying F low Channel P roperties f or the C athode..................................2457 33.2.6.5.3. Specifying P orous E lectrode P roperties f or the C athode.............................2458 33.2.6.5.4. Specifying C atalyst La yer Properties f or the C athode..................................2459 33.2.6.5.5. Specifying C ell Z one C onditions f or the C athode........................................2459 33.2.6.6. Setting A dvanced P roperties ( Advanc edTab).....................................................2460 33.2.6.6.1. Setting C ontact Resistivities f or the F uel C ell and E lectrolysis M odel...........2460 33.2.6.6.2. Setting C oolan t Channel P roperties f or the F uel C ell and E lectrolysis M od- el..............................................................................................................................2461 33.2.6.6.3. Managing S tacks f or the F uel C ell and E lectrolysis M odel............................2462 33.2.6.7. Reporting on the S olution ( Rep ortsTab)............................................................2464 33.2.7. Modeling C urrent Collec tors.......................................................................................2464 33.2.8. Fuel C ell and E lectrolysis M odel B oundar y Conditions .................................................2465 33.2.9. Solution G uidelines f or the F uel C ell and E lectrolysis M odel.........................................2466 33.2.10. Postpr ocessing the F uel C ell and E lectrolysis M odel...................................................2467 33.2.11. User-A ccessible F unctions .........................................................................................2468 33.2.11.1. Compiling the C ustomiz ed F uel C ell and E lectrolysis S ource Code.....................2471 33.2.11.1.1. Compiling the C ustomiz ed S ource Code U nder Linux ...............................2471 33.2.11.1.2. Compiling the C ustomiz ed S ource Code U nder Windo ws.........................2472 33.3. Using the S olid O xide F uel C ell With U nresolv ed E lectrolyte Model.......................................2473 33.3.1. Limita tion on M odeling S olid O xide F uel C ells .............................................................2473 33.3.2. Installing the S olid O xide F uel C ell With U nresolv ed E lectrolyte Model.........................2473 lvRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide33.3.3. Loading the S olid O xide F uel C ell With U nresolv ed E lectrolyte Module .........................2473 33.3.4. Solid O xide F uel C ell With U nresolv ed E lectrolyte Module S et U p Procedur e................2474 33.3.5. Setting the P aramet ers f or the SOFC With U nresolv ed E lectrolyte Model......................2482 33.3.6. Setting U p the E lectrochemistr y Paramet ers................................................................2484 33.3.7. Setting U p the E lectrode-E lectrolyte Interfaces............................................................2486 33.3.8. Setting U p the E lectric Field M odel P aramet ers............................................................2488 33.3.9. User-A ccessible F unctions f or the S olid O xide F uel C ell With U nresolv ed E lectrolyte Model...................................................................................................................................2489 33.3.9.1. Compiling the C ustomiz ed S olid O xide F uel C ell With U nresolv ed E lectrolyte Source Code..............................................................................................................................2490 33.3.9.1.1. Compiling the C ustomiz ed S ource Code U nder Linux .................................2490 33.3.9.1.2. Compiling the C ustomiz ed S ource Code U nder Windo ws...........................2491 34. Modeling M agnet ohydrodynamics ...........................................................................................2493 34.1. Introduction ........................................................................................................................2493 34.2. Implemen tation ..................................................................................................................2493 34.2.1. Solving M agnetic Induc tion and E lectric Potential E qua tions .......................................2494 34.2.2. Calcula tion of MHD Variables ......................................................................................2494 34.2.3. MHD In teraction with F luid F lows...............................................................................2494 34.2.4. MHD In teraction with D iscrete Phase M odel................................................................2495 34.2.5. Gener al User-D efined F unctions ..................................................................................2495 34.3. Using the ANSY S Fluen t MHD M odule ..................................................................................2495 34.3.1. MHD M odule Installa tion ............................................................................................2495 34.3.2. Loading the MHD M odule ...........................................................................................2495 34.3.3. MHD M odel S etup ......................................................................................................2496 34.3.3.1. Enabling the MHD M odel...................................................................................2497 34.3.3.2. Selec ting an MHD M etho d.................................................................................2498 34.3.3.3. Applying an Ex ternal M agnetic F ield ..................................................................2499 34.3.3.4. Setting U p Boundar y Conditions ........................................................................2502 34.3.3.5. Solution C ontrols...............................................................................................2506 34.3.4. MHD S olution and P ostpr ocessing ..............................................................................2507 34.3.4.1. MHD M odel Initializa tion ....................................................................................2507 34.3.4.2. Iteration ............................................................................................................2508 34.3.4.3. Postpr ocessing ..................................................................................................2508 34.3.5. Limita tions .................................................................................................................2509 34.4. Guidelines F or U sing the ANSY S Fluen t MHD M odel.............................................................2509 34.4.1. Installing the MHD M odule .........................................................................................2510 34.4.2. An Overview of U sing the MHD M odule ......................................................................2510 34.5. Definitions of the M agnetic F ield .........................................................................................2512 34.6. External M agnetic F ield D ata Format...................................................................................2513 35. Modeling C ontinuous F ibers.....................................................................................................2515 35.1. Installing the C ontinuous F iber M odule ...............................................................................2516 35.2. Loading the C ontinuous F iber M odule .................................................................................2516 35.3. Getting S tarted With the C ontinuous F iber M odule ..............................................................2517 35.3.1. User-D efined M emor y and the A djust F unction S etup .................................................2518 35.3.2. Source Term UDF S etup ..............................................................................................2518 35.4. Fiber M odels and Options ...................................................................................................2519 35.4.1. Choosing a F iber M odel..............................................................................................2520 35.4.2. Including In teraction With Sur rounding F low..............................................................2521 35.4.3. Including La teral D rag on Sur rounding F low...............................................................2521 35.4.4. Including F iber R adia tion In teraction ..........................................................................2521 35.4.5. Viscous H eating of F ibers............................................................................................2521 35.4.6. Drag, Heat and M ass Transf er C orrelations ...................................................................2521 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. lviUser's G uide35.5. Fiber M aterial P roperties .....................................................................................................2522 35.5.1. The C oncept of F iber M aterials....................................................................................2522 35.5.2. Descr iption of F iber Properties ....................................................................................2522 35.6. Defining F ibers....................................................................................................................2524 35.6.1. Overview ....................................................................................................................2524 35.6.2. Fiber Injec tion Types...................................................................................................2525 35.6.3. Working with F iber Injec tions ......................................................................................2526 35.6.3.1. Creating F iber Injec tions ....................................................................................2527 35.6.3.2. Modifying F iber Injec tions ..................................................................................2527 35.6.3.3. Copying F iber Injec tions .....................................................................................2527 35.6.3.4. Deleting F iber Injec tions ....................................................................................2527 35.6.3.5. Initializing F iber Injec tions ..................................................................................2527 35.6.3.6. Computing F iber Injec tions ................................................................................2527 35.6.3.7. Print Fiber Injec tions ..........................................................................................2528 35.6.3.8. Read D ata of F iber Injec tions ..............................................................................2528 35.6.3.9. Write Data of F iber Injec tions ..............................................................................2528 35.6.3.10. Write Binar y Data of F iber Injec tions .................................................................2528 35.6.3.11. List F iber Injec tions ..........................................................................................2529 35.6.4. Defining F iber Injec tion P roperties ..............................................................................2529 35.6.5. Point Properties S pecific t o Single F iber Injec tions .......................................................2533 35.6.6. Point Properties S pecific t o Line F iber Injec tions ..........................................................2533 35.6.7. Point Properties S pecific t o Matrix Fiber Injec tions .......................................................2533 35.6.8. Define F iber G rids.......................................................................................................2534 35.6.8.1. Equidistan t Fiber G rids.......................................................................................2534 35.6.8.2. One-S ided F iber G rids........................................................................................2534 35.6.8.3. Two-Sided F iber G rids........................................................................................2535 35.6.8.4. Three-S ided F iber G rids......................................................................................2535 35.7. User-D efined F unctions (UDFs) f or the C ontinuous F iber M odel............................................2536 35.7.1. UDF S etup ..................................................................................................................2537 35.7.1.1. Linux S ystems ....................................................................................................2537 35.7.1.2. Windo ws Systems ..............................................................................................2537 35.7.2. Customizing the fib er_fluen t_in terface.c File for Your F iber M odel A pplic ation .............2537 35.7.2.1. Example: Heat Transf er C oefficien t UDF ..............................................................2538 35.7.2.2. Example: Fiber Specific H eat Capacit y UDF .........................................................2539 35.7.3. Compile F iber M odel UDFs ..........................................................................................2540 35.7.3.1. Linux S ystems ....................................................................................................2540 35.7.3.2. NT/W indo ws Systems .........................................................................................2541 35.7.4. Hook UDFs t o the C ontinuous F iber M odel..................................................................2541 35.8. Fiber M odel S olution C ontrols.............................................................................................2542 35.9. Postpr ocessing f or the C ontinuous F ibers............................................................................2544 35.9.1. Displa y of F iber Locations and G rid Points...................................................................2544 35.9.2. Exchange Terms of F ibers............................................................................................2546 35.9.3. Analyzing F iber Variables ............................................................................................2547 35.9.3.1. XY Plots .............................................................................................................2547 35.9.3.2. Fiber D ispla y......................................................................................................2549 35.9.4. Running the F iber M odule in P arallel ...........................................................................2550 36. Creating Reduc ed Or der M odels (R OMs) ..................................................................................2551 36.1. Defining a R OM ...................................................................................................................2551 36.2. Reduc ed Or der M odel (R OM) E valua tion in F luen t................................................................2553 36.3. ROM Limita tions .................................................................................................................2557 37. Using the S olver........................................................................................................................2559 37.1. Overview of U sing the S olver...............................................................................................2559 lviiRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide37.1.1. Choosing the S olver...................................................................................................2561 37.2. Choosing the S patial D iscretiza tion Scheme ........................................................................2562 37.2.1. First-Or der A ccur acy vs. Second-Or der A ccur acy..........................................................2563 37.2.1.1. First- t o Higher-Or der B lending ..........................................................................2564 37.2.2. Other D iscretiza tion Schemes .....................................................................................2564 37.2.3. Choosing the P ressur e Interpolation Scheme ..............................................................2564 37.2.4. Choosing the D ensit y Interpolation Scheme ................................................................2565 37.2.5. High Or der Term R elaxa tion (HO TR).............................................................................2565 37.2.5.1. Limita tions ........................................................................................................2567 37.2.6. User Inputs .................................................................................................................2568 37.3. Pressur e-Based S olver Settings ............................................................................................2570 37.3.1. Choosing the P ressur e-Velocity Coupling M etho d.......................................................2570 37.3.1.1. SIMPLE v s. SIMPLEC ............................................................................................2570 37.3.1.2. PISO ..................................................................................................................2571 37.3.1.3. Fractional S tep M etho d......................................................................................2571 37.3.1.4. Coupled .............................................................................................................2571 37.3.1.5. User Inputs ........................................................................................................2572 37.3.2. Setting U nder-R elaxa tion F actors................................................................................2573 37.3.2.1. User Inputs ........................................................................................................2573 37.3.3. Setting S olution C ontrols f or the N on-I terative Solver..................................................2575 37.3.3.1. User Inputs ........................................................................................................2576 37.3.3.2. NITA Exp ert Options ...........................................................................................2578 37.3.3.3. Compa tibilit y of the NIT A Scheme with O ther ANSY S Fluen t Models ....................2579 37.3.4. Equa tion Or der ...........................................................................................................2580 37.4. Densit y-Based S olver Settings .............................................................................................2581 37.4.1. Changing the C ourant Numb er...................................................................................2581 37.4.1.1. Courant Numb ers f or the D ensit y-Based Explicit F ormula tion ..............................2582 37.4.1.2. Courant Numb ers f or the D ensit y-Based Implicit F ormula tion .............................2582 37.4.1.3. User Inputs ........................................................................................................2582 37.4.2. Convective Flux Types.................................................................................................2583 37.4.3. Convergenc e Acceleration f or S tretched M eshes (C ASM) .............................................2584 37.4.4. Preventing D ivergenc e Using L ocal Under-R elaxa tion ..................................................2586 37.4.5. Specifying the Explicit R elaxa tion ................................................................................2587 37.4.6. Turning On F AS M ultigr id............................................................................................2587 37.4.6.1. Setting C oarse G rid Levels..................................................................................2588 37.4.6.2. Using R esidual S moothing t o Incr ease the C ourant Numb er................................2588 37.5. Setting A lgebr aic M ultigr id Paramet ers................................................................................2589 37.5.1. Specifying the M ultigr id Cycle Type.............................................................................2591 37.5.2. Setting the Termina tion and R esidual R educ tion P aramet ers.......................................2591 37.5.3. Setting the S tabiliza tion M etho d.................................................................................2591 37.5.4. Additional A lgebr aic M ultigr id Paramet ers..................................................................2592 37.5.4.1. Fixed C ycle P aramet ers.......................................................................................2593 37.5.4.2. Coarsening P aramet ers......................................................................................2593 37.5.4.3. Smoother Types.................................................................................................2594 37.5.4.4. Flexible C ycle P aramet ers...................................................................................2595 37.5.4.5. Setting the Verbosity..........................................................................................2595 37.5.4.6. Retur ning t o the D efault M ultigr id Paramet ers....................................................2596 37.5.5. Setting F AS M ultigr id Paramet ers................................................................................2596 37.5.5.1. Comba ting C onvergenc e Trouble .......................................................................2596 37.5.5.2. “Industr ial-S trength ” FAS M ultigr id......................................................................2596 37.6. Setting S olution Limits ........................................................................................................2599 37.6.1. Limiting the Values of S olution Variables .....................................................................2600 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. lviiiUser's G uide37.6.2. Adjusting the P ositivit y Rate Limit ...............................................................................2601 37.6.3. Resetting S olution Limits ............................................................................................2601 37.7. Setting M ulti-S tage Time-S tepping P aramet ers....................................................................2601 37.7.1. Changing the M ulti-S tage Scheme ..............................................................................2602 37.7.1.1. Changing the C oefficien ts and N umb er of S tages ...............................................2602 37.7.1.2. Controlling U pdates to Dissipa tion and Viscous S tresses .....................................2603 37.7.1.3. Resetting the M ulti-S tage P aramet ers.................................................................2603 37.8. Selec ting G radien t Limit ers.................................................................................................2603 37.9. Initializing the S olution .......................................................................................................2604 37.9.1. Initializing the En tire Flow Field U sing S tandar d Initializa tion .......................................2605 37.9.1.1. Saving and R esetting Initial Values ......................................................................2607 37.9.2. Patching Values in S elec ted C ells.................................................................................2607 37.9.2.1. Using R egist ers..................................................................................................2609 37.9.2.2. Using F ield F unctions .........................................................................................2609 37.9.2.3. Using P atching La ter in the S olution P rocess.......................................................2609 37.10. Full M ultigr id (FMG) Initializa tion .......................................................................................2609 37.10.1. Steps in U sing FMG Initializa tion ...............................................................................2610 37.10.2. Convergenc e Strategies f or FMG Initializa tion ............................................................2611 37.11. Hybrid Initializa tion ...........................................................................................................2611 37.11.1. Steps in U sing H ybrid Initializa tion ............................................................................2611 37.11.2. Solution S trategies f or H ybrid Initializa tion ................................................................2614 37.12. Performing S teady-State Calcula tions ................................................................................2614 37.12.1. Updating UDF P rofiles ..............................................................................................2616 37.12.2. Resetting D ata..........................................................................................................2616 37.12.3. Data Sampling f or S teady Statistics ...........................................................................2616 37.13. Performing P seudo Transien t Calcula tions ..........................................................................2617 37.13.1. Setting P seudo Transien t Explicit R elaxa tion F actors..................................................2619 37.13.1.1. User Inputs ......................................................................................................2620 37.13.2. Setting S olution C ontrols f or the P seudo Transien t Metho d.......................................2621 37.13.3. Solving P seudo-T ransien t Flow..................................................................................2622 37.14. Performing Time-D ependen t Calcula tions ..........................................................................2626 37.14.1. User Inputs f or Time-D ependen t Problems ................................................................2627 37.14.1.1. Additional Inputs .............................................................................................2640 37.14.2. CFL-B ased Time S tepping .........................................................................................2640 37.14.2.1. The CFL-B ased Time S tepping A lgor ithm ..........................................................2640 37.14.2.2. Specifying P aramet ers f or CFL-B ased Time S tepping .........................................2641 37.14.3. Error-B ased Time S tepping ........................................................................................2642 37.14.3.1. The E rror-B ased Time S tepping A lgor ithm ........................................................2642 37.14.3.2. Specifying P aramet ers f or E rror-B ased Time S tepping .......................................2643 37.14.4. Multiphase-S pecific Time S tepping ...........................................................................2643 37.14.4.1. The M ultiphase-S pecific Time S tepping A lgor ithm ............................................2644 37.14.4.2. Specifying P aramet ers f or M ultiphase-S pecific Time S tepping ...........................2644 37.14.5. Postpr ocessing f or Time-D ependen t Problems ..........................................................2645 37.15. Monit oring S olution C onvergenc e.....................................................................................2646 37.15.1. Monit oring R esiduals ................................................................................................2647 37.15.1.1. Definition of R esiduals f or the P ressur e-Based S olver........................................2647 37.15.1.2. Definition of R esiduals f or the D ensit y-Based S olver..........................................2648 37.15.1.3. Overview of U sing the R esidual M onit ors D ialog Box........................................2650 37.15.1.4. Printing and P lotting R esiduals .........................................................................2650 37.15.1.5. Storing R esidual Hist ory Points.........................................................................2650 37.15.1.6. Controlling N ormaliza tion and Sc aling ..............................................................2651 37.15.1.7. Choosing a C onvergenc e Criterion ...................................................................2652 lixRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide37.15.1.8. Modifying C onvergenc e Criteria.......................................................................2654 37.15.1.9. Disabling M onit oring .......................................................................................2654 37.15.1.10. Plot P aramet ers..............................................................................................2654 37.15.1.11. Postpr ocessing R esidual Values ......................................................................2655 37.15.2. Monit oring S tatistics .................................................................................................2655 37.15.3. Monit oring S olution Q uantities .................................................................................2656 37.16. Convergenc e Conditions ...................................................................................................2657 37.16.1. Setting U p the C onvergenc e Conditions D ialog Box...................................................2658 37.17. Executing C ommands D uring the C alcula tion ....................................................................2660 37.17.1. Defining M acros.......................................................................................................2662 37.17.2. Saving F iles D uring the C alcula tion ...........................................................................2664 37.18. Automa tic Initializa tion of the S olution and C ase M odific ation ...........................................2664 37.18.1. Altering the S olution Initializa tion and C ase M odific ation af ter C alcula ting ................2669 37.19. Anima ting the S olution .....................................................................................................2670 37.19.1. Creating an A nima tion D efinition ..............................................................................2670 37.19.1.1. Guidelines f or C reating an A nima tion D efinition ...............................................2673 37.19.2. Playing an A nima tion S equenc e................................................................................2673 37.19.2.1. Modifying the View ..........................................................................................2674 37.19.2.2. Modifying the P layback S peed .........................................................................2674 37.19.2.3. Playing B ack an Ex cerpt....................................................................................2674 37.19.2.4. “Fast-F orwarding ” the A nima tion ......................................................................2674 37.19.2.5. Continuous A nima tion .....................................................................................2675 37.19.2.6. Stopping the A nima tion ...................................................................................2675 37.19.2.7. Advancing the A nima tion F rame b y Frame .......................................................2675 37.19.2.8. Deleting an A nima tion S equenc e.....................................................................2675 37.19.3. Saving an A nima tion S equenc e.................................................................................2675 37.19.3.1. Solution A nima tion F ile....................................................................................2676 37.19.3.2. Picture File.......................................................................................................2676 37.19.3.3. MPEG F ile.........................................................................................................2677 37.19.4. Reading an A nima tion S equenc e..............................................................................2677 37.20. Check ing Your C ase S etup .................................................................................................2677 37.20.1. Automa tic Implemen tation .......................................................................................2679 37.20.2. Manual Implemen tation ...........................................................................................2679 37.20.2.1. Check ing the M esh ..........................................................................................2680 37.20.2.2. Check ing M odel S elec tions ..............................................................................2682 37.20.2.3. Check ing B oundar y and C ell Z one C onditions ..................................................2684 37.20.2.4. Check ing M aterial P roperties ............................................................................2687 37.20.2.5. Check ing the S olver Settings ............................................................................2688 37.21. Convergenc e and S tabilit y.................................................................................................2690 37.21.1. Judging C onvergenc e...............................................................................................2691 37.21.2. Step-b y-Step S olution P rocesses ...............................................................................2692 37.21.2.1. Selec ting a Subset of the S olution E qua tions ....................................................2692 37.21.2.2. Turning R eactions On and O ff...........................................................................2693 37.21.3. Modifying A lgebr aic M ultigr id Paramet ers.................................................................2693 37.21.4. Modifying the M ulti-S tage P aramet ers......................................................................2694 37.21.5. Robustness on M eshes of P oor Q ualit y......................................................................2694 37.21.6. Warped-F ace Gradien t Correction .............................................................................2697 37.22. Solution S teering ..............................................................................................................2698 37.22.1. Overview of S olution S teering...................................................................................2698 37.22.2. Solution S teering S trategy........................................................................................2698 37.22.2.1. Initializa tion .....................................................................................................2699 37.22.3. Using S olution S teering ............................................................................................2699 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. lxUser's G uide38. Adapting the M esh ....................................................................................................................2705 38.1. Using A daption ...................................................................................................................2705 38.1.1. Adaption Example ......................................................................................................2705 38.1.2. Adaption G uidelines ...................................................................................................2707 38.2. Refining and C oarsening .....................................................................................................2708 38.3. Adaption Examples .............................................................................................................2710 38.3.1. Boundar y Cell R egist er................................................................................................2710 38.3.2. Region C ell R egist er....................................................................................................2713 38.3.3. Field Variable C ell R egist ers (gr adien ts, scaling , and so on) ...........................................2716 38.3.4. Expr ession A daption R efinemen t................................................................................2718 38.4. Anisotr opic A daption ..........................................................................................................2721 38.4.1. Limita tions of A nisotr opic A daption ............................................................................2722 38.4.2. Performing A nisotr opic A daption ...............................................................................2722 38.4.3. Boundar y La yer R edistr ibution ....................................................................................2723 38.5. Geometr y-Based A daption ..................................................................................................2723 38.5.1. Performing G eometr y-Based A daption .......................................................................2724 39. Creating S urfaces and C ell Regist ers f or D ispla ying and Rep orting D ata................................2727 39.1. Using Sur faces....................................................................................................................2727 39.1.1. Zone Sur faces.............................................................................................................2729 39.1.2. Partition Sur faces.......................................................................................................2730 39.1.3. Impr int Sur faces.........................................................................................................2732 39.1.4. Point Sur faces............................................................................................................2734 39.1.4.1. Using the P oint Tool...........................................................................................2736 39.1.4.1.1. Initializing the P oint Tool...........................................................................2736 39.1.4.1.2. Transla ting the P oint Tool..........................................................................2736 39.1.4.1.3. Resetting the P oint Tool.............................................................................2737 39.1.5. Structural Point Sur faces.............................................................................................2737 39.1.6. Line and R ake Sur faces...............................................................................................2738 39.1.6.1. Using the Line Tool.............................................................................................2740 39.1.6.1.1. Initializing the Line Tool.............................................................................2740 39.1.6.1.2. Transla ting the Line Tool............................................................................2741 39.1.6.1.3. Rotating the Line Tool................................................................................2741 39.1.6.1.4. Resizing the Line Tool................................................................................2742 39.1.6.1.5. Resetting the Line Tool..............................................................................2742 39.1.7. Plane Sur faces............................................................................................................2742 39.1.7.1. Using the P lane Tool...........................................................................................2744 39.1.7.1.1. Initializing the P lane Tool...........................................................................2745 39.1.7.1.2. Transla ting the P lane Tool..........................................................................2745 39.1.7.1.3. Rotating the P lane Tool..............................................................................2745 39.1.7.1.4. Resizing the P lane Tool..............................................................................2746 39.1.7.1.5. Resetting the P lane Tool............................................................................2746 39.1.8. Quadr ic Sur faces........................................................................................................2746 39.1.9. Isosur faces.................................................................................................................2748 39.1.10. Clipping Sur faces......................................................................................................2750 39.1.11. Transf orming Sur faces..............................................................................................2753 39.1.12. Grouping , Editing , Renaming , and D eleting Sur faces..................................................2755 39.1.12.1. Grouping Sur faces...........................................................................................2757 39.1.12.2. Editing and R enaming Sur faces........................................................................2757 39.1.12.3. Deleting Sur faces.............................................................................................2758 39.1.12.4. Sur face Statistics ..............................................................................................2758 39.2. Using C ell R egist ers.............................................................................................................2758 39.2.1. Region .......................................................................................................................2759 lxiRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide39.2.1.1. Defining a R egion ..............................................................................................2759 39.2.1.2. Setting U p a R egion C ell R egist er........................................................................2759 39.2.2. Boundar y...................................................................................................................2761 39.2.3. Variable Limit er..........................................................................................................2762 39.2.4. Field Variable ..............................................................................................................2763 39.2.4.1. Approaches F or D eriving F ield Values .................................................................2763 39.2.4.2. Setting U p a F ield Variable C ell R egist er..............................................................2765 39.2.5. Residuals ....................................................................................................................2766 39.2.6. Volume .......................................................................................................................2767 39.2.6.1. Volume C ell R egist er A pproach ...........................................................................2767 39.2.6.2. Setting U p a Volume C ell R egist er.......................................................................2768 39.2.7. Yplus/Ystar .................................................................................................................2769 39.2.7.1. Yplus/Ystar A pproach .........................................................................................2769 39.2.7.2. Setting up a Yplus/Ystar C ell R egist er..................................................................2769 39.2.8. Manage C ell R egist ers.................................................................................................2770 39.2.9. Cell R egist er Op erations ..............................................................................................2771 39.2.10. Copying and R enaming C ell R egist ers.......................................................................2773 40. Displa ying G raphics ..................................................................................................................2775 40.1. Basic G raphics G ener ation ...................................................................................................2775 40.1.1. Displa ying the M esh ...................................................................................................2776 40.1.1.1. Gener ating M esh or Outline P lots .......................................................................2778 40.1.1.2. Mesh and Outline D ispla y Options ......................................................................2780 40.1.1.2.1. Modifying the M esh C olors ........................................................................2780 40.1.1.2.2. Adding F eatures to an Outline D ispla y.......................................................2781 40.1.1.2.3. Drawing P artition B oundar ies....................................................................2782 40.1.1.2.4. Shrinking F aces and C ells in the D ispla y.....................................................2782 40.1.1.3. Creating and U sing M esh P lot D efinitions ...........................................................2783 40.1.2. Displa ying C ontours and P rofiles .................................................................................2784 40.1.2.1. Gener ating C ontour and P rofile P lots ..................................................................2785 40.1.2.2. Contour and P rofile P lot Options ........................................................................2788 40.1.2.2.1. Drawing F illed C ontours or P rofiles ............................................................2788 40.1.2.2.2. Specifying the R ange of M agnitudes D ispla yed..........................................2789 40.1.2.2.3. Including the M esh in the C ontour P lot......................................................2791 40.1.2.2.4. Choosing N ode or C ell Values ....................................................................2791 40.1.2.2.5. Storing C ontour P lot S ettings ....................................................................2791 40.1.2.3. Creating and U sing C ontour P lot D efinitions .......................................................2792 40.1.3. Displa ying Vectors......................................................................................................2794 40.1.3.1. Gener ating Vector P lots ......................................................................................2794 40.1.3.2. Displa ying R elative Velocity Vectors....................................................................2796 40.1.3.3. Vector P lot Options ............................................................................................2796 40.1.3.3.1. Scaling the Vectors....................................................................................2796 40.1.3.3.2. Skipping Vectors.......................................................................................2797 40.1.3.3.3. Drawing Vectors in the P lane of the Sur face...............................................2797 40.1.3.3.4. Displa ying F ixed-L ength Vectors................................................................2798 40.1.3.3.5. Displa ying Vector C omp onen ts..................................................................2798 40.1.3.3.6. Specifying the R ange of M agnitudes D ispla yed..........................................2798 40.1.3.3.7. Changing the Sc alar F ield U sed f or C olor ing the Vectors.............................2798 40.1.3.3.8. Displa ying Vectors U sing a S ingle C olor ......................................................2799 40.1.3.3.9. Including the M esh in the Vector P lot.........................................................2799 40.1.3.3.10. Changing the A rrow Characteristics .........................................................2799 40.1.3.4. Creating and M anaging C ustom Vectors.............................................................2799 40.1.3.4.1. Creating C ustom Vectors...........................................................................2800 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. lxiiUser's G uide40.1.3.4.2. Manipula ting , Saving , and L oading C ustom Vectors....................................2801 40.1.3.5. Creating and U sing Vector P lot D efinitions ..........................................................2802 40.1.4. Displa ying P athlines ...................................................................................................2802 40.1.4.1. Steps f or G ener ating P athlines ...........................................................................2803 40.1.4.2. Options f or P athline P lots ...................................................................................2804 40.1.4.2.1. Including the M esh in the P athline D ispla y.................................................2805 40.1.4.2.2. Controlling the P athline S tyle....................................................................2805 40.1.4.2.3. Controlling P athline C olors ........................................................................2806 40.1.4.2.4. “Thinning ” Pathlines ...................................................................................2806 40.1.4.2.5. Coarsening P athlines .................................................................................2807 40.1.4.2.6. Reversing the P athlines .............................................................................2807 40.1.4.2.7. Plotting Oil-F low Pathlines .........................................................................2807 40.1.4.2.8. Controlling the P ulse M ode.......................................................................2807 40.1.4.2.9. Controlling the A ccur acy...........................................................................2807 40.1.4.2.10. Plotting R elative Pathlines .......................................................................2807 40.1.4.2.11. Gener ating an X Y Plot A long P athline Trajec tories....................................2808 40.1.4.2.12. Saving P athline D ata................................................................................2808 40.1.4.2.12.1. Standar d Type................................................................................2809 40.1.4.2.12.2. Geometr y Type...............................................................................2810 40.1.4.2.12.3. EnS ight Type...................................................................................2810 40.1.4.2.13. Choosing N ode or C ell Values ..................................................................2811 40.1.4.3. Creating and U sing P athline D efinitions ..............................................................2811 40.1.5. Displa ying a Sc ene ......................................................................................................2812 40.1.5.1. Gener ating a Sc ene ............................................................................................2812 40.1.6. Displa ying R esults on a S weep Sur face........................................................................2813 40.1.6.1. Steps f or G ener ating a P lot U sing a S weep Sur face..............................................2813 40.1.6.2. Anima ting a S weep Sur face Displa y....................................................................2815 40.1.7. Hiding the G raphics Windo w D ispla y..........................................................................2815 40.2. Customizing the G raphics D ispla y........................................................................................2816 40.2.1. Advanced G raphics O verlays.......................................................................................2817 40.2.2. Opening M ultiple G raphics Windo ws..........................................................................2818 40.2.2.1. Setting the A ctive Windo w.................................................................................2819 40.2.3. Changing the L egend D ispla y.....................................................................................2819 40.2.3.1. Controlling the Titles , Axes, Ruler, Logo, and C olor map .........................................2820 40.2.3.2. Editing the L egend ............................................................................................2820 40.2.3.3. Adding a Title t o the C aption ..............................................................................2820 40.2.3.4. Enabling/D isabling the A xes..............................................................................2821 40.2.3.5. Enabling/D isabling the R uler ..............................................................................2821 40.2.3.6. Modifying and D ispla ying/Hiding the L ogo........................................................2821 40.2.3.7. Color map A lignmen t.........................................................................................2821 40.2.4. Adding Text to the G raphics Windo w..........................................................................2821 40.2.4.1. Adding Text Using the A nnota te Dialog Box........................................................2822 40.2.4.2. Editing Existing A nnota tion Text.........................................................................2823 40.2.4.3. Clearing A nnota tion Text....................................................................................2823 40.2.5. Changing the C olor map .............................................................................................2823 40.2.5.1. Predefined C olor maps .......................................................................................2824 40.2.5.2. Selec ting a C olor map .........................................................................................2825 40.2.5.2.1. Specifying the C olor map S ize and Sc ale.....................................................2825 40.2.5.2.2. Changing the N umb er Format...................................................................2825 40.2.5.3. Displa ying C olor map Lab el................................................................................2826 40.2.5.4. Creating a C ustomiz ed C olor map .......................................................................2827 40.2.6. Adding Ligh ts.............................................................................................................2829 lxiiiRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide40.2.6.1. Turning on Ligh ting E ffects with the D ispla y Options D ialog Box.........................2829 40.2.6.2. Turning on Ligh ting E ffects with the Ligh ts Dialog Box.......................................2829 40.2.6.3. Defining Ligh t Sources.......................................................................................2830 40.2.6.3.1. Remo ving a Ligh t......................................................................................2831 40.2.6.3.2. Resetting the Ligh t Definitions ..................................................................2831 40.2.7. Modifying the R ender ing Options ...............................................................................2831 40.2.7.1. Graphics D evice Inf ormation ..............................................................................2833 40.3. Controlling the M ouse B utton F unctions ..............................................................................2833 40.3.1. Button F unctions ........................................................................................................2833 40.3.2. Modifying the M ouse B utton F unctions .......................................................................2834 40.4. Viewing the A pplic ation Windo w.........................................................................................2835 40.5. Modifying the View .............................................................................................................2835 40.5.1. Selec ting a View .........................................................................................................2836 40.5.2. Manipula ting the D ispla y............................................................................................2837 40.5.2.1. Scaling and C entering........................................................................................2838 40.5.2.2. Rotating the D ispla y...........................................................................................2839 40.5.2.2.1. Spinning the D ispla y with the M ouse .........................................................2839 40.5.2.3. Transla ting the D ispla y.......................................................................................2840 40.5.2.4. Zooming the D ispla y..........................................................................................2840 40.5.3. Controlling P ersp ective and C amer a Paramet ers..........................................................2842 40.5.3.1. Persp ective and Or thographic Views..................................................................2842 40.5.3.2. Modifying C amer a Paramet ers...........................................................................2842 40.5.4. Saving and R estoring Views........................................................................................2843 40.5.4.1. Restoring the D efault View .................................................................................2843 40.5.4.2. Retur ning t o Previous Views...............................................................................2843 40.5.4.3. Saving Views......................................................................................................2843 40.5.4.4. Reading View F iles .............................................................................................2844 40.5.4.5. Deleting Views...................................................................................................2844 40.5.5. Mirroring and P eriodic R epeats...................................................................................2844 40.5.5.1. Periodic R epeats for G raphics .............................................................................2846 40.5.5.2. Mirroring f or G raphics ........................................................................................2848 40.6. Advanced Sc ene C omp osition .............................................................................................2848 40.6.1. Selec ting the O bjec t(s) t o be Manipula ted...................................................................2849 40.6.2. Changing an O bjec t’s Displa y Properties .....................................................................2850 40.6.2.1. Controlling Visibilit y...........................................................................................2851 40.6.2.2. Controlling O bjec t Color and Transpar ency.........................................................2851 40.6.3. Transf orming G eometr ic O bjec ts in a Sc ene ................................................................2852 40.6.3.1. Transla ting O bjec ts............................................................................................2853 40.6.3.2. Rotating O bjec ts................................................................................................2853 40.6.3.3. Scaling O bjec ts..................................................................................................2853 40.6.3.4. Displa ying the M eridional View ..........................................................................2854 40.6.4. Modifying I so-V alues ..................................................................................................2854 40.6.4.1. Steps f or M odifying I so-V alues ............................................................................2854 40.6.5. Modifying P athline A ttribut es.....................................................................................2854 40.6.6. Deleting an O bjec t from the Sc ene .............................................................................2855 40.6.7. Adding a B ounding F rame ..........................................................................................2855 40.7. Anima ting G raphics ............................................................................................................2857 40.7.1. Creating an A nima tion ................................................................................................2858 40.7.1.1. Deleting Ke y Frames ..........................................................................................2859 40.7.2. Playing an A nima tion ..................................................................................................2859 40.7.2.1. Playing B ack an Ex cerpt......................................................................................2860 40.7.2.2. "Fast-F orwarding" the A nima tion ........................................................................2860 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. lxivUser's G uide40.7.2.3. Continuous A nima tion .......................................................................................2860 40.7.2.4. Stopping the A nima tion .....................................................................................2860 40.7.2.5. Advancing the A nima tion F rame b y Frame .........................................................2860 40.7.3. Saving an A nima tion ..................................................................................................2861 40.7.3.1. Anima tion F ile...................................................................................................2861 40.7.3.2. Picture File.........................................................................................................2861 40.7.3.3. MPEG F ile..........................................................................................................2861 40.7.4. Reading an A nima tion F ile..........................................................................................2862 40.7.5. Notes on A nima tion ....................................................................................................2862 40.8. Hist ogram and X Y Plots .......................................................................................................2862 40.8.1. Plot Types...................................................................................................................2863 40.8.1.1. XY Plots .............................................................................................................2863 40.8.1.2. Hist ograms ........................................................................................................2863 40.8.2. XY Plots of S olution D ata............................................................................................2864 40.8.2.1. Steps f or G ener ating S olution X Y Plots ...............................................................2864 40.8.2.2. Options f or Solution X Y Plots ..............................................................................2868 40.8.2.2.1. Including Ex ternal D ata in the S olution X Y Plot..........................................2868 40.8.2.2.2. Choosing N ode or C ell Values ....................................................................2868 40.8.2.2.3. Saving the P lot D ata to a F ile.....................................................................2869 40.8.3. XY Plots of F ile D ata....................................................................................................2869 40.8.3.1. Steps f or G ener ating X Y Plots of D ata in Ex ternal F iles.........................................2869 40.8.4. XY Plots of P rofiles ......................................................................................................2870 40.8.4.1. Steps f or G ener ating P lots of P rofile D ata............................................................2871 40.8.4.2. Steps f or G ener ating P lots of In terpolated P rofile D ata........................................2872 40.8.5. XY Plots of C ircumf erential A verages ...........................................................................2872 40.8.5.1. Steps f or G ener ating an X Y Plot of C ircumf erential A verages ...............................2873 40.8.5.2. Customizing the A ppearance of the P lot.............................................................2874 40.8.6. XY Plot F ile F ormat.....................................................................................................2874 40.8.7. Residual P lots .............................................................................................................2875 40.8.8. Hist ograms .................................................................................................................2875 40.8.8.1. Steps f or G ener ating Hist ogram P lots .................................................................2876 40.8.8.2. Options f or Hist ogram P lots ...............................................................................2877 40.8.8.2.1. Specifying the R ange of Values P lotted......................................................2877 40.8.9. Modifying A xis A ttribut es...........................................................................................2877 40.8.9.1. Using the A xes D ialog Box..................................................................................2878 40.8.9.1.1. Changing the A xis Lab el............................................................................2878 40.8.9.1.2. Changing the F ormat of the D ata Lab els....................................................2878 40.8.9.1.3. Choosing L ogarithmic or D ecimal Sc aling ..................................................2878 40.8.9.1.4. Resetting the R ange of the A xis.................................................................2878 40.8.9.1.5. Controlling the M ajor and M inor R ules .......................................................2879 40.8.10. Modifying C urve Attribut es.......................................................................................2879 40.8.10.1. Using the C urves D ialog Box.............................................................................2879 40.8.10.1.1. Changing the Line S tyle...........................................................................2880 40.8.10.1.2. Changing the M arker Style......................................................................2880 40.8.10.1.3. Previewing the C urve Style......................................................................2881 40.9. Turbomachiner y Postpr ocessing ..........................................................................................2881 40.9.1. Defining the Turbomachiner y Topology......................................................................2881 40.9.1.1. Boundar y Types.................................................................................................2883 40.9.2. Gener ating R eports of Turbomachiner y Data...............................................................2884 40.9.2.1. Computing Turbomachiner y Quantities ..............................................................2885 40.9.2.1.1. Mass F low.................................................................................................2885 40.9.2.1.2. Swirl Numb er............................................................................................2886 lxvRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide40.9.2.1.3. Average Total P ressur e...............................................................................2886 40.9.2.1.4. Average Total Temp erature........................................................................2886 40.9.2.1.5. Average F low Angles .................................................................................2887 40.9.2.1.6. Passage L oss C oefficien t............................................................................2887 40.9.2.1.7. Axial F orce................................................................................................2888 40.9.2.1.8. Torque ......................................................................................................2888 40.9.2.1.9. Efficiencies f or P umps and C ompr essors ....................................................2888 40.9.2.1.9.1. Incompr essible F lows.......................................................................2889 40.9.2.1.9.2. Compr essible F lows..........................................................................2889 40.9.2.1.10. Efficiencies f or Turbines ...........................................................................2890 40.9.2.1.10.1. Incompr essible F lows......................................................................2891 40.9.2.1.10.2. Compr essible F lows........................................................................2891 40.9.3. Displa ying Turbomachiner y Averaged C ontours ..........................................................2892 40.9.3.1. Steps f or G ener ating Turbomachiner y Averaged C ontour P lots ...........................2892 40.9.3.2. Contour P lot Options .........................................................................................2894 40.9.4. Displa ying Turbomachiner y 2D C ontours ....................................................................2894 40.9.4.1. Steps f or G ener ating Turbo 2D C ontour P lots ......................................................2894 40.9.4.2. Contour P lot Options .........................................................................................2896 40.9.5. Gener ating A veraged X Y Plots of Turbomachiner y Solution D ata.................................2896 40.9.5.1. Steps f or G ener ating Turbo Averaged X Y Plots ....................................................2896 40.9.6. Globally S etting the Turbomachiner y Topology...........................................................2897 40.9.7. Turbomachiner y-Specific Variables ..............................................................................2897 40.10. Fast F ourier Transf orm (FFT ) Postpr ocessing .......................................................................2898 40.10.1. Limita tions of the FFT A lgor ithm ...............................................................................2898 40.10.2. Windo wing ...............................................................................................................2898 40.10.3. Fast F ourier Transf orm (FFT )......................................................................................2899 40.10.4. Using the FFT U tility..................................................................................................2901 40.10.4.1. Loading D ata for S pectral Analy sis....................................................................2901 40.10.4.2. Customizing the Input and D efining the S pectrum S moothing .........................2902 40.10.4.2.1. Customizing the Input S ignal D ata Set.....................................................2903 40.10.4.2.2. Spectrum S moothing Through S ignal S egmen tation ................................2903 40.10.4.2.3. Viewing D ata Statistics ............................................................................2904 40.10.4.2.4. Customizing Titles and Lab els..................................................................2904 40.10.4.2.5. Applying the C hanges in the Input S ignal D ata........................................2904 40.10.4.3. Customizing the Output ...................................................................................2904 40.10.4.3.1. Specifying a F unction f or the Y Axis..........................................................2904 40.10.4.3.2. Specifying a F unction f or the X A xis.........................................................2906 40.10.4.3.3. Specifying Output Options ......................................................................2907 40.10.4.3.4. Specifying a Windo wing Technique ..........................................................2908 40.10.4.3.5. Specifying Lab els and Titles .....................................................................2908 41. Rep orting A lphanumer ic D ata..................................................................................................2909 41.1. Reporting C onventions .......................................................................................................2909 41.2. Monit oring and R eporting S olution D ata.............................................................................2910 41.2.1. Creating R eport Definitions ........................................................................................2910 41.2.1.1. Sur face Report Definitions .................................................................................2914 41.2.1.2. Volume R eport Definitions .................................................................................2915 41.2.1.3. Force and M omen t Report Definitions ................................................................2917 41.2.1.4. Flux R eport Definition ........................................................................................2922 41.2.1.5. DPM R eport Definition .......................................................................................2924 41.2.1.6. User D efined R eport Definition ..........................................................................2926 41.2.1.6.1. User D efined R eport Definition F unction ....................................................2926 41.2.1.6.2. User D efined R eport Definition F unction H ooking......................................2927 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. lxviUser's G uide41.2.1.7. Expr ession R eport Definition ..............................................................................2927 41.2.2. Report Files and R eport Plots ......................................................................................2929 41.2.2.1. Creating R eport Files ..........................................................................................2929 41.2.2.2. Creating R eport Plots .........................................................................................2932 41.3. Creating Output P aramet ers................................................................................................2935 41.4. Fluxes Through B oundar ies.................................................................................................2937 41.4.1. Gener ating a F lux R eport............................................................................................2937 41.4.2. Flux R eporting f or R eacting F lows...............................................................................2939 41.4.3. Flux R eporting with P articles .......................................................................................2941 41.4.4. Flux R eporting with M ultiphase ..................................................................................2941 41.4.5. Flux R eporting with O ther Volumetr ic Sources............................................................2942 41.5. Forces on B oundar ies..........................................................................................................2942 41.5.1. Gener ating a F orce, Momen t, or C enter of P ressur e Report...........................................2942 41.5.1.1. Example ............................................................................................................2944 41.6. Projec ted Sur face Area C alcula tions .....................................................................................2946 41.7. Sur face Integration ..............................................................................................................2947 41.7.1. Gener ating a Sur face Integral Report..........................................................................2947 41.8. Volume In tegration .............................................................................................................2949 41.8.1. Gener ating a Volume In tegral Report..........................................................................2949 41.9. Hist ogram R eports..............................................................................................................2951 41.10. Discrete Phase ...................................................................................................................2951 41.11. S2S Inf ormation .................................................................................................................2951 41.12. Reference Values ...............................................................................................................2952 41.12.1. Setting R eference Values ...........................................................................................2952 41.12.2. Setting the R eference Zone .......................................................................................2954 41.13. Summar y Reports of C ase S ettings ....................................................................................2954 41.13.1. Gener ating a Summar y Report..................................................................................2954 41.14. System R esour ce Usage .....................................................................................................2955 41.14.1. Processor Inf ormation ...............................................................................................2955 41.14.2. Memor y Inf ormation ................................................................................................2956 41.14.3. Process and M odel Timers .........................................................................................2956 42. Field F unc tion D efinitions .........................................................................................................2959 42.1. Node, Cell, and F acet Values .................................................................................................2959 42.1.1. Cell Values ..................................................................................................................2959 42.1.2. Node Values ...............................................................................................................2960 42.1.2.1. Vertex Values f or P oints That Are Not M esh N odes ...............................................2960 42.1.3. Facet Values ................................................................................................................2960 42.1.3.1. Facet Values on Z one Sur faces............................................................................2961 42.1.3.2. Facet Values on P ostpr ocessing Sur faces.............................................................2961 42.2. Velocity Reporting Options ..................................................................................................2961 42.3. Field Variables List ed b y Categor y........................................................................................2963 42.4. Alphab etical Listing of F ield Variables and Their D efinitions ..................................................2988 42.5. Custom F ield F unctions .......................................................................................................3038 42.5.1. Creating a C ustom F ield F unction ................................................................................3039 42.5.1.1. Using the C alcula tor B uttons ..............................................................................3041 42.5.1.2. Using the F ield F unctions List .............................................................................3041 42.5.2. Manipula ting , Saving , and L oading C ustom F ield F unctions .........................................3042 42.5.3. Sample C ustom F ield F unctions ..................................................................................3043 43. Parallel P rocessing ....................................................................................................................3045 43.1. Introduction t o Parallel P rocessing .......................................................................................3045 43.1.1. Recommended U sage of P arallel ANSY S Fluen t...........................................................3047 43.2. Starting P arallel ANSY S Fluen t Using F luen t Launcher ..........................................................3047 lxviiRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide43.2.1. Setting P arallel Scheduler Options in F luen t Launcher .................................................3051 43.2.2. Setting A dditional Options When R unning on R emot e Linux M achines ........................3054 43.2.2.1. Setting J ob Scheduler Options When R unning on R emot e Linux M achines ..........3057 43.3. Starting P arallel ANSY S Fluen t on a Windo ws System...........................................................3058 43.3.1. Starting P arallel ANSY S Fluen t on a Windo ws System U sing C ommand Line Options ....3058 43.3.1.1. Starting P arallel ANSY S Fluen t with the M icrosof t Job Scheduler .........................3061 43.4. Starting P arallel ANSY S Fluen t on a Linux S ystem.................................................................3063 43.4.1. Starting P arallel ANSY S Fluen t on a Linux S ystem U sing C ommand Line Options ..........3064 43.4.2. Setting U p Your R emot e Shell and S ecur e Shell C lients................................................3066 43.4.2.1. Configur ing the rsh Client................................................................................3067 43.4.2.2. Configur ing the ssh Client................................................................................3067 43.5. Mesh P artitioning and L oad B alancing .................................................................................3067 43.5.1. Overview of M esh P artitioning ....................................................................................3068 43.5.2. Partitioning the M esh A utoma tically ...........................................................................3069 43.5.2.1. Reporting D uring A uto Partitioning ....................................................................3071 43.5.3. Partitioning the M esh M anually and B alancing the L oad ..............................................3071 43.5.3.1. Guidelines f or P artitioning the M esh ...................................................................3071 43.5.4. Using the P artitioning and L oad B alancing D ialog Box.................................................3071 43.5.4.1. Partitioning .......................................................................................................3071 43.5.4.1.1. Example of S etting S elec ted C ell R egist ers t o Specified P artition IDs ...........3077 43.5.4.1.2. Partitioning Within Z ones or R egist ers.......................................................3079 43.5.4.1.3. Reporting D uring P artitioning ...................................................................3080 43.5.4.1.4. Resetting the P artition P aramet ers.............................................................3080 43.5.4.2. Load B alancing ..................................................................................................3081 43.5.5. Mesh P artitioning M etho ds.........................................................................................3083 43.5.5.1. Partition M etho ds..............................................................................................3083 43.5.5.2. Optimiza tions ....................................................................................................3087 43.5.5.3. Pretesting ..........................................................................................................3088 43.5.5.4. Using the P artition F ilter.....................................................................................3089 43.5.6. Check ing the P artitions ...............................................................................................3089 43.5.6.1. Interpreting P artition S tatistics ...........................................................................3089 43.5.6.2. Examining P artitions G raphic ally ........................................................................3092 43.5.7. Load D istribution ........................................................................................................3092 43.5.8. Troublesho oting .........................................................................................................3093 43.6. Using G ener al Purpose G raphics P rocessing U nits (GPGPU s) With the A lgebr aic M ultigr id (AMG) Solver.........................................................................................................................................3093 43.6.1. Requir emen ts.............................................................................................................3094 43.6.2. Limita tions .................................................................................................................3094 43.6.3. Using and M anaging GPGPU s.....................................................................................3094 43.7. Controlling the Threads .......................................................................................................3095 43.8. Check ing N etwork Connec tivit y..........................................................................................3096 43.9. Check ing and Impr oving P arallel P erformanc e.....................................................................3096 43.9.1. Parallel C heck .............................................................................................................3097 43.9.2. Check ing P arallel P erformanc e....................................................................................3097 43.9.2.1. Check ing La tency and B and width ......................................................................3099 43.9.3. Optimizing the P arallel S olver.....................................................................................3101 43.9.3.1. Incr easing the R eport Interval............................................................................3101 43.9.3.2. Accelerating View F actor C alcula tions f or G ener al Purpose C omputing on G raphics Processing U nits (GPGPU s)..............................................................................................3101 43.9.3.3. Accelerating D iscrete Or dina tes (DO) R adia tion C alcula tions ...............................3102 43.9.4. Clearing the Linux F ile C ache B uffers...........................................................................3103 44. Design A naly sis and Optimiza tion ............................................................................................3105 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. lxviiiUser's G uide44.1. The A djoin t Solver...............................................................................................................3105 44.1.1. Gener al O bser vables ...................................................................................................3107 44.1.2. Gener al Op erations ....................................................................................................3111 44.1.3. Discrete Versus C ontinuous A djoin t Solver..................................................................3112 44.1.4. Discrete Adjoin t Solver O verview ................................................................................3112 44.1.5. Adjoin t Solver Stabiliza tion .........................................................................................3116 44.1.6. Solution-B ased A daption ............................................................................................3117 44.1.7. Using The D ata To Impr ove A D esign ...........................................................................3117 44.1.7.1. Smoothing and M esh M orphing .........................................................................3118 44.1.7.1.1. Polynomials-B ased A pproach ....................................................................3119 44.1.7.1.2. Direct Interpolation M etho d......................................................................3119 44.2. Using the A djoin t Solver......................................................................................................3120 44.2.1. Model C onsider ations f or U sing A djoin t Solver............................................................3121 44.2.1.1. Basic A ssumptions and C onsist ency Checks ........................................................3121 44.2.1.2. User-D efined S ources.........................................................................................3123 44.2.2. Defining O bser vables .................................................................................................3124 44.2.2.1. Creating N ew O bser vables .................................................................................3124 44.2.2.2. Editing O bser vable D efinitions ...........................................................................3126 44.2.2.3. Selec ting an O bser vable f or S ensitivit y Calcula tion .............................................3130 44.2.3. Solving the A djoin t.....................................................................................................3131 44.2.3.1. Using the A djoin t Solution M etho ds D ialog Box..................................................3131 44.2.3.2. Using the A djoin t Solution C ontrols D ialog Box..................................................3132 44.2.3.2.1. Stabiliza tion S trategies , Schemes , and S ettings ...........................................3134 44.2.3.2.1.1. Dissipa tion Scheme ..........................................................................3136 44.2.3.2.1.2. Residual M inimiza tion Scheme .........................................................3137 44.2.3.2.1.3. Spatial S tabiliza tion Scheme .............................................................3138 44.2.3.2.1.4. Modal S tabiliza tion Scheme ..............................................................3140 44.2.3.3. Working with A djoin t Residual M onit ors.............................................................3142 44.2.3.4. Running the A djoin t Calcula tion .........................................................................3143 44.2.4. Postpr ocessing of A djoin t Solutions ............................................................................3144 44.2.4.1. Field D ata..........................................................................................................3144 44.2.4.2. Scalar D ata........................................................................................................3148 44.2.5. Modifying the G eometr y Using the D esign Tool..........................................................3148 44.2.5.1. Defining the R egion f or the D esign C hange ........................................................3151 44.2.5.2. Defining R egion C onditions ...............................................................................3153 44.2.5.3. Exp orting S ensitivit y Data..................................................................................3154 44.2.5.4. Defining O bser vable O bjec tives.........................................................................3154 44.2.5.5. Defining C onditions f or the D eformation ............................................................3155 44.2.5.6. Design Tool N umer ics........................................................................................3162 44.2.5.7. Shap e Modific ation ............................................................................................3164 44.2.6. Using the G radien t-Based Optimiz er...........................................................................3168 44.3. The M esh M orpher/Optimiz er..............................................................................................3178 44.3.1. Limita tions .................................................................................................................3178 44.3.2. The Optimiza tion P rocess............................................................................................3178 44.3.3. Optimiz ers.................................................................................................................3179 44.3.3.1. The C ompass Optimiz er.....................................................................................3179 44.3.3.2. The NE WUO A Optimiz er.....................................................................................3179 44.3.3.3. The S imple x Optimiz er.......................................................................................3180 44.3.3.4. The Torczon Optimiz er.......................................................................................3180 44.3.3.5. The P owell Optimiz er.........................................................................................3180 44.3.3.6. The R osenbr ock Optimiz er.................................................................................3181 44.4. Using the M esh M orpher/Optimiz er.....................................................................................3181 lxixRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide45. Performing S ystem C oupling S imula tions U sing F luen t...........................................................3207 45.1. Performing S ystem C oupling in ANSY S Workbench ..............................................................3207 45.2. Performing C ommand Line S ystem C oupling .......................................................................3208 45.2.1. Gener ating a S ystem C oupling F ile..............................................................................3209 45.3. Supp orted C apabilities and Limita tions ...............................................................................3209 45.4. Variables A vailable f or System C oupling ...............................................................................3211 45.4.1. Force transf erred t o System C oupling fr om a Wall B oundar y........................................3212 45.4.2. Force transf erred t o System C oupling fr om a P orous J ump B oundar y...........................3212 45.4.3. Displac emen t transf erred fr om S ystem C oupling .........................................................3214 45.4.4. Displac emen t transf erred fr om S ystem C oupling t o a S liding M esh Z one .....................3214 45.4.5. Absolut e Pressur e Example .........................................................................................3214 45.5. System C oupling R elated S ettings in F luen t.........................................................................3215 45.6. FSI S etup R ecommenda tions f or Fluen t-Mechanic al Couplings ............................................3216 45.6.1. Using C ontact Detection f or Fluen t-Mechanic al FSI P roblems ......................................3216 45.6.2. Recommenda tions f or D ynamic M esh S ettings f or Fluen t-Mechanic al FSI ....................3218 45.6.3. Patholo gies & C andida te Resolutions f or Fluen t-Mechanic al FSI ...................................3218 45.6.3.1. Mesh F olds within the F irst C oupling S teps .........................................................3218 45.6.3.2. Deformed P rism La yers ......................................................................................3219 45.6.3.2.1. Using B oundar y La yer Smoothing and R egion F ace Remeshing .................3219 45.6.3.2.2. Overset M eshes ........................................................................................3223 45.6.3.3. Interior E lemen ts ha ve High S kewness or A re Too Lar ge/small .............................3225 45.7. How Fluen t’s Execution is A ffected b y System C ouplings ......................................................3227 45.8. Restar ting F luen t Analy ses as P art of S ystem C ouplings ........................................................3227 45.8.1. Gener ating F luen t Restar t Files ...................................................................................3228 45.8.2. Specify a R estar t Point in F luen t..................................................................................3228 45.8.3. Making C hanges in F luen t Before Restar ting ...............................................................3228 45.8.4. Recovering the F luen t Restar t Point after a Workbench C rash ......................................3229 45.9. System C oupling c ase with F luen t using P atched D ata.........................................................3229 45.10. Running F luen t as a S ystem C oupling P articipan t from the C ommand Line .........................3230 45.11. Troublesho oting Two-W ay Coupled A naly sis P roblems .......................................................3231 45.12. Product Lic ensing C onsider ations when using S ystem C oupling .........................................3231 46. Customizing F luen t...................................................................................................................3233 47.Task P age Ref erenc e Guide .......................................................................................................3235 47.1. Meshing Task P age ..............................................................................................................3235 47.2. Setup Task P age ..................................................................................................................3235 47.3. Gener al Task P age ...............................................................................................................3235 47.3.1. Scale M esh D ialog Box................................................................................................3238 47.3.2. Mesh D ispla y Dialog Box.............................................................................................3239 47.3.3. Set U nits D ialog Box...................................................................................................3242 47.3.4. Define U nit D ialog Box................................................................................................3244 47.3.5. Mesh C olors D ialog Box..............................................................................................3244 47.4. Models Task P age ................................................................................................................3245 47.4.1. Multiphase M odel D ialog Box.....................................................................................3248 47.4.2. Ener gy Dialog Box......................................................................................................3252 47.4.3. Viscous M odel D ialog Box...........................................................................................3253 47.4.4. Radia tion M odel D ialog Box........................................................................................3269 47.4.5. View F actors and C lustering D ialog Box.......................................................................3273 47.4.6. Participa ting B oundar y Zones D ialog Box....................................................................3276 47.4.7. Solar C alcula tor D ialog Box.........................................................................................3277 47.4.8. Heat Exchanger M odel D ialog Box..............................................................................3278 47.4.9. Dual C ell H eat Exchanger D ialog Box...........................................................................3279 47.4.10. Set D ual C ell H eat Exchanger D ialog Box...................................................................3280 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. lxxUser's G uide47.4.11. Heat Transf er D ata Table D ialog Box..........................................................................3282 47.4.12. NTU Table D ialog Box................................................................................................3284 47.4.13. Copy From D ialog Box..............................................................................................3284 47.4.14. Ungroup ed M acro Heat Exchanger D ialog Box..........................................................3285 47.4.15. Velocity Effectiveness C urve Dialog Box.....................................................................3289 47.4.16. Core Porosity Model D ialog Box................................................................................3289 47.4.17. Macro Heat Exchanger G roup D ialog Box..................................................................3291 47.4.18. Species M odel D ialog Box.........................................................................................3294 47.4.19. Coal C alcula tor D ialog Box........................................................................................3312 47.4.20. Integration P aramet ers D ialog Box............................................................................3315 47.4.21. Flamelet 3D Sur faces D ialog Box...............................................................................3317 47.4.22. Flamelet 2D C urves D ialog Box..................................................................................3319 47.4.23. Unsteady Flamelet P aramet ers D ialog Box.................................................................3320 47.4.24. Flamelet F luid Z ones D ialog Box...............................................................................3321 47.4.25. Selec t Transp orted Sc alars D ialog Box.......................................................................3321 47.4.26. PDF Table D ialog Box................................................................................................3322 47.4.27. Spark Ignition D ialog Box..........................................................................................3325 47.4.28. Set Spark Ignition D ialog Box....................................................................................3325 47.4.29. Autoignition M odel D ialog Box.................................................................................3327 47.4.30. Iner t Dialog Box........................................................................................................3330 47.4.31. NOx Model D ialog Box..............................................................................................3332 47.4.32. SOx Model D ialog Box..............................................................................................3339 47.4.33. Soot M odel D ialog Box.............................................................................................3343 47.4.34. Sticking C oefficien ts D ialog Box................................................................................3351 47.4.35. Mechanism D ialog Box.............................................................................................3351 47.4.36. Reactor N etwork Dialog Box.....................................................................................3353 47.4.37. Decoupled D etailed C hemistr y Dialog Box................................................................3356 47.4.38. Reacting C hannel M odel D ialog Box..........................................................................3356 47.4.39. Reacting C hannel 2D C urves D ialog Box....................................................................3358 47.4.40. Discrete Phase M odel D ialog Box..............................................................................3360 47.4.41. DEM C ollisions D ialog Box.........................................................................................3367 47.4.42. Create Collision P artner D ialog Box...........................................................................3368 47.4.43. Copy Collision P artner D ialog Box.............................................................................3368 47.4.44. Rename C ollision P artner D ialog Box.........................................................................3369 47.4.45. DEM C ollision S ettings D ialog Box.............................................................................3369 47.4.46. Solidific ation and M elting D ialog Box........................................................................3370 47.4.47. Acoustics M odel D ialog Box......................................................................................3371 47.4.48. Acoustic S ources D ialog Box.....................................................................................3374 47.4.49. Acoustic R eceivers D ialog Box...................................................................................3376 47.4.50. Basic S hap es D ialog Box............................................................................................3377 47.4.51. Interior C ell Z one S elec tion D ialog Box......................................................................3378 47.4.52. Structural M odel D ialog Box......................................................................................3378 47.4.53. Euler ian Wall F ilm D ialog Box....................................................................................3379 47.4.54. Potential D ialog Box.................................................................................................3384 47.5. Materials Task P age .............................................................................................................3384 47.5.1. Create/Edit M aterials D ialog Box.................................................................................3386 47.5.2. Fluen t Database M aterials D ialog Box.........................................................................3396 47.5.3. Open D atabase D ialog Box.........................................................................................3397 47.5.4. User-D efined D atabase M aterials D ialog Box...............................................................3398 47.5.5. Copy Case M aterial D ialog Box....................................................................................3399 47.5.6. Material P roperties D ialog Box....................................................................................3399 47.5.7. Edit P roperty Metho ds D ialog Box...............................................................................3400 lxxiRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide47.5.8. New M aterial N ame D ialog Box...................................................................................3401 47.5.9. Polynomial P rofile D ialog Box.....................................................................................3402 47.5.10. Piecewise-Linear P rofile D ialog Box...........................................................................3403 47.5.11. Piecewise-P olynomial P rofile D ialog Box...................................................................3404 47.5.12. Model Options D ialog Box........................................................................................3405 47.5.13. Compr essible Liquid D ialog Box................................................................................3405 47.5.14. User-D efined F unctions D ialog Box...........................................................................3406 47.5.15. Suther land La w D ialog Box.......................................................................................3407 47.5.16. Power La w D ialog Box...............................................................................................3408 47.5.17. Non-N ewtonian P ower La w D ialog Box.....................................................................3409 47.5.18. Carreau M odel D ialog Box.........................................................................................3409 47.5.19. Cross M odel D ialog Box............................................................................................3411 47.5.20. Herschel-B ulkley Dialog Box......................................................................................3411 47.5.21. Biaxial C onduc tivit y Dialog Box.................................................................................3412 47.5.22. Cylindr ical Or thotr opic C onduc tivit y Dialog Box........................................................3413 47.5.23. Orthotr opic C onduc tivit y Dialog Box.........................................................................3415 47.5.24. Anisotr opic C onduc tion - P rincipal C omp onen ts D ialog Box......................................3416 47.5.25. Anisotr opic C onduc tivit y Dialog Box.........................................................................3417 47.5.26. Species D ialog Box...................................................................................................3417 47.5.27. Reactions D ialog Box................................................................................................3419 47.5.28. Backward Reaction P aramet ers D ialog Box................................................................3423 47.5.29. Third-Body Efficienc y Dialog Box...............................................................................3423 47.5.30. Pressur e-Dependen t Reaction D ialog Box.................................................................3424 47.5.31. Coverage-D ependen t Reaction D ialog Box................................................................3426 47.5.32. Reference Mass F ractions D ialog Box.........................................................................3427 47.5.33. Reaction M echanisms D ialog Box..............................................................................3428 47.5.34. Site Paramet ers D ialog Box.......................................................................................3430 47.5.35. Mass D iffusion C oefficien ts D ialog Box......................................................................3431 47.5.36. Thermal D iffusion C oefficien ts D ialog Box.................................................................3432 47.5.37. UDS D iffusion C oefficien ts D ialog Box.......................................................................3433 47.5.38. WSGGM U ser S pecified D ialog Box............................................................................3434 47.5.39. Gray-Band A bsor ption C oefficien t Dialog Box............................................................3435 47.5.40. Delta-E ddingt on Sc attering F unction D ialog Box.......................................................3435 47.5.41. Gray-Band R efractive Inde x Dialog Box......................................................................3436 47.5.42. Single R ate Model D ialog Box...................................................................................3436 47.5.43. Two Comp eting R ates M odel D ialog Box...................................................................3437 47.5.44. CPD M odel D ialog Box..............................................................................................3438 47.5.45. Kinetics/D iffusion-Limit ed C ombustion M odel D ialog Box.........................................3439 47.5.46. Intrinsic C ombustion M odel D ialog Box.....................................................................3440 47.5.47. Multiple Sur face Reactions D ialog Box......................................................................3441 47.5.48. Edit M aterial D ialog Box............................................................................................3442 47.6. Phases ................................................................................................................................3443 47.6.1. Primar y Phase D ialog Box...........................................................................................3444 47.6.2. Secondar y Phase D ialog Box.......................................................................................3444 47.6.3. Discrete Phase D ialog Box...........................................................................................3448 47.6.4. Phase In teraction D ialog Box......................................................................................3451 47.7. Cell Z one C onditions Task P age ............................................................................................3455 47.7.1. Fluid D ialog Box.........................................................................................................3457 47.7.2. Solid D ialog Box.........................................................................................................3467 47.7.3. Copy Conditions D ialog Box........................................................................................3469 47.7.4. Operating C onditions D ialog Box................................................................................3470 47.7.5. Selec t Input P aramet er D ialog Box..............................................................................3472 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. lxxiiUser's G uide47.7.6. Profiles D ialog Box......................................................................................................3473 47.7.7. Replic ate Profile D ialog Box........................................................................................3475 47.7.8. Orient Profile D ialog Box.............................................................................................3476 47.7.9. Write Profile D ialog Box..............................................................................................3478 47.8. Boundar y Conditions Task P age ...........................................................................................3479 47.8.1. Axis D ialog Box...........................................................................................................3482 47.8.2. Degassing D ialog Box.................................................................................................3482 47.8.3. Exhaust F an D ialog Box...............................................................................................3483 47.8.4. Fan D ialog Box...........................................................................................................3488 47.8.5. Inlet Vent Dialog Box..................................................................................................3490 47.8.6. Intake Fan D ialog Box.................................................................................................3496 47.8.7. Interface Dialog Box...................................................................................................3501 47.8.8. Interior D ialog Box......................................................................................................3501 47.8.9. Mass-F low Inlet D ialog Box.........................................................................................3502 47.8.10. Mass-F low Outlet D ialog Box.....................................................................................3507 47.8.11. Outflo w D ialog Box...................................................................................................3511 47.8.12. Outlet Vent Dialog Box..............................................................................................3513 47.8.13. Periodic D ialog Box...................................................................................................3517 47.8.14. Porous J ump D ialog Box...........................................................................................3518 47.8.15. Pressur e Far-Field D ialog Box....................................................................................3520 47.8.16. Pressur e Inlet D ialog Box...........................................................................................3524 47.8.17. Pressur e Outlet D ialog Box........................................................................................3530 47.8.18. Radia tor D ialog Box..................................................................................................3537 47.8.19. RANS/LES In terface Dialog Box..................................................................................3539 47.8.20. Symmetr y Dialog Box...............................................................................................3540 47.8.21. Velocity Inlet D ialog Box...........................................................................................3540 47.8.22. Wall D ialog Box.........................................................................................................3549 47.8.23. Periodic C onditions D ialog Box.................................................................................3564 47.9. Overset In terfaces Task P age ................................................................................................3565 47.9.1. Create/Edit O verset In terfaces D ialog Box...................................................................3566 47.10. Dynamic M esh Task P age ...................................................................................................3567 47.10.1. Mesh M etho d Settings D ialog Box.............................................................................3570 47.10.2. Mesh S moothing P aramet ers D ialog Box...................................................................3573 47.10.3. Mesh Sc ale Inf o Dialog Box.......................................................................................3574 47.10.4. Options D ialog Box...................................................................................................3575 47.10.5. In-C ylinder Output C ontrols D ialog Box.....................................................................3578 47.10.6. Six DOF P roperties D ialog Box...................................................................................3580 47.10.7. Flow Controls D ialog Box..........................................................................................3583 47.10.8. Dynamic M esh E vents D ialog Box..............................................................................3584 47.10.9. Define E vent Dialog Box............................................................................................3585 47.10.10. Events Preview D ialog Box......................................................................................3587 47.10.11. Dynamic M esh Z ones D ialog Box............................................................................3587 47.10.12. Orientation C alcula tor D ialog Box...........................................................................3595 47.10.13. Infla tion S ettings D ialog Box...................................................................................3596 47.10.14. CutCell B oundar y Zones Inf o Dialog Box..................................................................3597 47.10.15. Zone Sc ale Inf o Dialog Box......................................................................................3597 47.10.16. Zone M otion D ialog Box.........................................................................................3598 47.10.17. Mesh M otion D ialog Box.........................................................................................3599 47.10.18. Autosave Case D uring M esh M otion P review D ialog Box..........................................3600 47.11. Reference Values Task P age ................................................................................................3601 47.12. Solution Task P age .............................................................................................................3602 47.13. Solution M etho ds Task P age ..............................................................................................3603 lxxiiiRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide47.13.1. Relaxa tion Options D ialog Box..................................................................................3606 47.14. Solution C ontrols Task P age ...............................................................................................3606 47.14.1. Equa tions D ialog Box................................................................................................3609 47.14.2. Solution Limits D ialog Box........................................................................................3610 47.14.3. Advanced S olution C ontrols D ialog Box....................................................................3611 47.15. Solution Initializa tion Task P age .........................................................................................3620 47.15.1. Acoustics Initializa tion D ialog Box.............................................................................3622 47.15.2. Patch D ialog Box.......................................................................................................3622 47.15.3. Hybrid Initializa tion D ialog Box.................................................................................3624 47.16. Calcula tion A ctivities Task P age ..........................................................................................3626 47.16.1. Autosave Dialog Box.................................................................................................3628 47.16.2. Data File Q uantities D ialog Box.................................................................................3630 47.16.3. Automa tic Exp ort Dialog Box....................................................................................3631 47.16.4. Automa tic P article Hist ory Data Exp ort Dialog Box....................................................3635 47.16.5. Execut e Commands D ialog Box.................................................................................3637 47.16.6. Define M acro Dialog Box...........................................................................................3638 47.16.7. Automa tic S olution Initializa tion and C ase M odific ation D ialog Box...........................3638 47.17. Run C alcula tion Task P age ..................................................................................................3640 47.17.1. Case C heck D ialog Box..............................................................................................3647 47.17.2. Adaptiv e Time S tepping D ialog Box..........................................................................3648 47.17.3. Simula tion S tatus D ialog Box....................................................................................3649 47.17.4. Solution S teering D ialog Box.....................................................................................3650 47.17.5. Acoustic S ources FFT D ialog Box...............................................................................3652 47.17.6. Acoustic S ignals D ialog Box......................................................................................3657 47.17.7. Sampling Options D ialog Box....................................................................................3659 47.18. Results Task P age ...............................................................................................................3660 47.19. Graphics and A nima tions Task P age ...................................................................................3660 47.19.1. Profile Options D ialog Box........................................................................................3663 47.19.2. Vector Options D ialog Box........................................................................................3664 47.19.3. Custom Vectors D ialog Box.......................................................................................3664 47.19.4. Vector D efinitions D ialog Box....................................................................................3665 47.19.5. Path S tyle A ttribut es D ialog Box................................................................................3667 47.19.6. Ribbon A ttribut es D ialog Box....................................................................................3667 47.19.7. Particle F ilter A ttribut es............................................................................................3668 47.19.8. Reporting Variables D ialog Box.................................................................................3669 47.19.9. Track S tyle A ttribut es D ialog Box...............................................................................3670 47.19.10. Particle S pher e Style A ttribut es D ialog Box..............................................................3670 47.19.11. Particle Vector S tyle A ttribut es D ialog Box...............................................................3671 47.19.12. Sweep Sur face Dialog Box.......................................................................................3672 47.19.13. Create Sur face Dialog Box.......................................................................................3674 47.19.14. Anima te Dialog Box................................................................................................3674 47.19.15. Save Picture Dialog Box...........................................................................................3676 47.19.16. Playback D ialog Box................................................................................................3679 47.19.17. Displa y Options D ialog Box.....................................................................................3681 47.19.18. Scene D escr iption D ialog Box..................................................................................3683 47.19.19. Displa y Properties D ialog Box..................................................................................3685 47.19.20. Transf ormations D ialog Box.....................................................................................3687 47.19.21. Iso-V alue D ialog Box...............................................................................................3688 47.19.22. Pathline A ttribut es D ialog Box.................................................................................3689 47.19.23. Bounding F rame D ialog Box....................................................................................3689 47.19.24. Views Dialog Box....................................................................................................3690 47.19.25. Write Views Dialog Box............................................................................................3692 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. lxxivUser's G uide47.19.26. Mirror P lanes D ialog Box.........................................................................................3693 47.19.27. Graphics P eriodicit y Dialog Box...............................................................................3693 47.19.28. Camer a Paramet ers D ialog Box................................................................................3695 47.19.29. Ligh ts D ialog Box....................................................................................................3696 47.19.30. Color map D ialog Box..............................................................................................3697 47.19.31. Color map E ditor D ialog Box....................................................................................3699 47.19.32. Annota te Dialog Box...............................................................................................3700 47.20. Plots Task P age ..................................................................................................................3702 47.20.1. Solution X Y Plot D ialog Box.......................................................................................3703 47.20.2. Hist ogram D ialog Box...............................................................................................3707 47.20.3. File X Y Plot D ialog Box..............................................................................................3708 47.20.4. Plot P rofile D ata D ialog Box.......................................................................................3711 47.20.5. Plot In terpolated D ata D ialog Box.............................................................................3711 47.20.6. Fourier Transf orm D ialog Box....................................................................................3712 47.20.7. Plot/M odify Input S ignal D ialog Box..........................................................................3715 47.20.8. Axes D ialog Box........................................................................................................3717 47.20.9. Curves D ialog Box.....................................................................................................3720 47.21. Reports Task P age ..............................................................................................................3721 47.21.1. Flux R eports D ialog Box............................................................................................3723 47.21.2. Force Reports D ialog Box..........................................................................................3724 47.21.3. Projec ted Sur face Areas D ialog Box...........................................................................3725 47.21.4. Sur face Integrals D ialog Box......................................................................................3726 47.21.5. Volume In tegrals D ialog Box.....................................................................................3730 47.21.6. Sample Trajec tories D ialog Box.................................................................................3732 47.21.7. Trajec tory Sample Hist ograms D ialog Box..................................................................3733 47.21.8. Particle Summar y Dialog Box....................................................................................3736 47.21.9. Heat Exchanger R eport Dialog Box............................................................................3736 47.21.10. Paramet ers D ialog Box............................................................................................3738 47.21.11. Use Input P aramet er in Scheme P rocedur e Dialog Box.............................................3739 47.21.12. Use Input P aramet er for UDF D ialog Box..................................................................3740 47.21.13. Rename D ialog Box.................................................................................................3741 47.21.14. Paramet er Expr ession D ialog Box............................................................................3742 47.21.15. Save Output P aramet er D ialog Box..........................................................................3743 47.22. Paramet ers and C ustomiza tion Task P age ...........................................................................3744 48. Ribbon Ref erenc e Guide ...........................................................................................................3745 48.1. File R ibbon Tab....................................................................................................................3745 48.1.1. File/R ead/M esh... ........................................................................................................3746 48.1.1.1. Read M esh Options D ialog Box...........................................................................3746 48.1.2. File/R ead/C ase............................................................................................................3747 48.1.3. File/R ead/D ata... .........................................................................................................3748 48.1.4. File/R ead/C ase & D ata... ..............................................................................................3748 48.1.5. File/R ead/PDF ..............................................................................................................3748 48.1.6. File/R ead/ISA T Table ....................................................................................................3749 48.1.7. File/R ead/DTRM R ays...................................................................................................3749 48.1.8. File/R ead/V iew F actors................................................................................................3749 48.1.9. File/R ead/P rofile ..........................................................................................................3749 48.1.10. File/R ead/Scheme .....................................................................................................3749 48.1.11. File/R ead/J ournal... ...................................................................................................3749 48.1.12. File/W rite/Case..........................................................................................................3749 48.1.13. File/W rite/Data... .......................................................................................................3750 48.1.14. File/W rite/Case & D ata... ............................................................................................3750 48.1.15. File/W rite/PDF ...........................................................................................................3750 lxxvRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide48.1.16. File/W rite/ISA T Table ..................................................................................................3750 48.1.17. File/W rite/Flamelet... .................................................................................................3751 48.1.18. File/W rite/Sur face Clusters.........................................................................................3751 48.1.19. File/W rite/Profile .......................................................................................................3751 48.1.20. File/W rite/Autosave...................................................................................................3751 48.1.21. File/W rite/Boundar y Mesh... ......................................................................................3751 48.1.22. File/W rite/Start Journal... ...........................................................................................3751 48.1.23. File/W rite/Stop J ournal.............................................................................................3751 48.1.24. File/W rite/Start Transcr ipt... .......................................................................................3751 48.1.25. File/W rite/Stop Transcr ipt..........................................................................................3752 48.1.26. File/Imp ort/AB AQUS/Input F ile..................................................................................3752 48.1.27. File/Imp ort/AB AQUS/F ilbin F ile..................................................................................3752 48.1.28. File/Imp ort/AB AQUS/ODB F ile...................................................................................3752 48.1.29. File/Imp ort/CFX/D efinition F ile..................................................................................3752 48.1.30. File/Imp ort/CFX/R esult F ile........................................................................................3752 48.1.31. File/Imp ort/CGNS/M esh... .........................................................................................3752 48.1.32. File/Imp ort/CGNS/D ata... ...........................................................................................3752 48.1.33. File/Imp ort/CGNS/M esh & D ata... ...............................................................................3752 48.1.34. File/Imp ort/EnS ight...................................................................................................3753 48.1.35. File/Imp ort/FIDAP ......................................................................................................3753 48.1.36. File/Imp ort/GAMBIT ...................................................................................................3753 48.1.37. File/Imp ort/HYPERMESH ASCII... ................................................................................3753 48.1.38. File/Imp ort/I-deas U niversal... ....................................................................................3753 48.1.39. File/Imp ort/LST C/Input F ile........................................................................................3753 48.1.40. File/Imp ort/LST C/State File........................................................................................3753 48.1.41. File/Imp ort/Marc POST ..............................................................................................3753 48.1.42. File/Imp ort/Mechanic al APDL/Input F ile.....................................................................3753 48.1.43. File/Imp ort/Mechanic al APDL/R esult F ile...................................................................3754 48.1.44. File/Imp ort/NASTR AN/B ulkda ta File...........................................................................3754 48.1.45. File/Imp ort/NASTR AN/Op2 F ile..................................................................................3754 48.1.46. File/Imp ort/PATRAN/N eutr al File................................................................................3754 48.1.47. File/Imp ort/PL OT3D/G rid File.....................................................................................3754 48.1.48. File/Imp ort/PL OT3D/R esult F ile..................................................................................3754 48.1.49. File/Imp ort/PT C M echanic a Design... .........................................................................3754 48.1.50. File/Imp ort/Tecplot... ................................................................................................3754 48.1.51. File/Imp ort/Fluen t 4 C ase F ile....................................................................................3754 48.1.52. File/Imp ort/PreBFC F ile..............................................................................................3755 48.1.53. File/Imp ort/Partition/M etis........................................................................................3755 48.1.54. File/Imp ort/Partition/M etis Z one ...............................................................................3755 48.1.55. File/Imp ort/CHEMKIN M echanism... ...........................................................................3755 48.1.55.1. Imp ort CHEMKIN F ormat Mechanism D ialog Box..............................................3755 48.1.56. File/Exp ort/Solution D ata... .......................................................................................3757 48.1.56.1. Exp ort Dialog Box............................................................................................3757 48.1.57. File/Exp ort/Particle Hist ory Data... .............................................................................3762 48.1.57.1. Exp ort Particle Hist ory Data D ialog Box.............................................................3762 48.1.58. File/Exp ort/During C alcula tion/S olution D ata... ..........................................................3763 48.1.59. File/Exp ort/During C alcula tion/P article Hist ory Data... ...............................................3763 48.1.60. File/Exp ort to CFD-P ost... ...........................................................................................3763 48.1.60.1. Exp ort to CFD-P ost D ialog Box.........................................................................3763 48.1.61. File/S olution F iles......................................................................................................3764 48.1.61.1. Solution F iles D ialog Box..................................................................................3764 48.1.62. File/In terpolate..........................................................................................................3765 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. lxxviUser's G uide48.1.62.1. Interpolate Data D ialog Box..............................................................................3765 48.1.63. File/FSI M apping/V olume ..........................................................................................3767 48.1.63.1. Volume FSI M apping D ialog Box.......................................................................3767 48.1.64. File/FSI M apping/Sur face...........................................................................................3769 48.1.64.1. Sur face FSI M apping D ialog Box.......................................................................3769 48.1.65. File/S ave Picture........................................................................................................3772 48.1.66. File/D ata File Q uantities .............................................................................................3772 48.1.67. File/B atch Options .....................................................................................................3772 48.1.67.1. Batch Options D ialog Box.................................................................................3772 48.1.68. File/Exit ....................................................................................................................3773 48.2. Dialog Boxes A vailable fr om the R ibbon...............................................................................3773 48.2.1. 1D S imula tion Libr ary Dialog Box................................................................................3776 48.2.2. Activate Cell Z ones D ialog Box....................................................................................3776 48.2.3. Adaption C ontrols D ialog Box.....................................................................................3777 48.2.4. Adaption D ispla y Options D ialog Box..........................................................................3778 48.2.5. Adjac ency Dialog Box.................................................................................................3780 48.2.6. Anima tion D efinition D ialog Box.................................................................................3781 48.2.7. Anisotr opic A daption D ialog Box................................................................................3784 48.2.8. Auto Create Options D ialog Box..................................................................................3785 48.2.9. Auto Partition M esh D ialog Box...................................................................................3785 48.2.10. Boundar y Adaption D ialog Box.................................................................................3786 48.2.11. Cell R egist er D ispla y Options D ialog Box...................................................................3788 48.2.12. Compiled UDFs D ialog Box.......................................................................................3789 48.2.13. Contours D ialog Box.................................................................................................3790 48.2.14. Convergenc e Conditions D ialog Box.........................................................................3793 48.2.15. Create/Edit M esh In terfaces D ialog Box.....................................................................3794 48.2.16. Custom F ield F unction C alcula tor D ialog Box.............................................................3797 48.2.17. Custom La ws Dialog Box...........................................................................................3799 48.2.18. Deactivate Cell Z ones D ialog Box..............................................................................3799 48.2.19. Define C ontrol Points D ialog Box...............................................................................3800 48.2.20. Delete Cell Z ones D ialog Box....................................................................................3802 48.2.21. Displa y Options - A daption D ialog Box......................................................................3803 48.2.22. DPM R eport Definition D ialog Box............................................................................3804 48.2.23. DPM S ource Report Definition ..................................................................................3807 48.2.24. Drag R eport Definition D ialog Box............................................................................3808 48.2.25. DTRM G raphics D ialog Box........................................................................................3811 48.2.26. DTRM R ays Dialog Box..............................................................................................3812 48.2.27. Edit M esh In terfaces D ialog Box................................................................................3813 48.2.28. Edit R eport File D ialog Box........................................................................................3815 48.2.29. Edit R eport Plot D ialog Box.......................................................................................3817 48.2.30. Execut e on D emand D ialog Box................................................................................3819 48.2.31. Expr ession D ialog Box...............................................................................................3819 48.2.32. Expr ession R eport Definition D ialog Box...................................................................3821 48.2.33. Field F unction D efinitions D ialog Box........................................................................3823 48.2.34. Flux R eport Definition D ialog Box.............................................................................3824 48.2.35. Force Report Definition D ialog Box...........................................................................3827 48.2.36. Fuse F ace Zones D ialog Box......................................................................................3829 48.2.37. Geometr y Based A daption C ontrols D ialog Box.........................................................3830 48.2.38. Geometr y Based A daption D ialog Box.......................................................................3830 48.2.39. Gradien t Adaption D ialog Box...................................................................................3831 48.2.40. Imp ort Particle D ata D ialog Box................................................................................3834 48.2.41. Impr int Sur face Dialog Box.......................................................................................3835 lxxviiRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide48.2.42. Impr ove Mesh D ialog Box.........................................................................................3836 48.2.43. Injec tions D ialog Box................................................................................................3837 48.2.44. Input Summar y Dialog Box.......................................................................................3838 48.2.45. Interface Options D ialog Box.....................................................................................3838 48.2.46. Interpreted UDFs D ialog Box.....................................................................................3840 48.2.47. Iso-C lip D ialog Box....................................................................................................3841 48.2.48. Iso-Sur face Dialog Box..............................................................................................3842 48.2.49. Iso-V alue A daption D ialog Box..................................................................................3843 48.2.50. Lift Report Definition D ialog Box...............................................................................3845 48.2.51. Line/R ake Sur face Dialog Box....................................................................................3847 48.2.52. Manage A daption R egist ers D ialog Box.....................................................................3848 48.2.53. Merge Z ones D ialog Box...........................................................................................3850 48.2.54. Mesh A daption C ontrols D ialog Box..........................................................................3851 48.2.55. Mesh In terfaces D ialog Box.......................................................................................3852 48.2.56. Mesh M orpher/Optimiz er D ialog Box........................................................................3854 48.2.57. Mixing P lanes D ialog Box..........................................................................................3862 48.2.58. Momen t Report Definition D ialog Box.......................................................................3864 48.2.59. Motion S ettings D ialog Box.......................................................................................3867 48.2.60. Multi E dit D ialog Box................................................................................................3872 48.2.61. New R eport File D ialog Box.......................................................................................3873 48.2.62. New R eport Plot D ialog Box......................................................................................3874 48.2.63. Objec tive Function D efinition D ialog Box..................................................................3876 48.2.64. Optimiza tion Hist ory Monit or D ialog Box..................................................................3878 48.2.65. Parallel C onnec tivit y Dialog Box................................................................................3879 48.2.66. Paramet er B ounds D ialog Box...................................................................................3880 48.2.67. Particle Tracks D ialog Box..........................................................................................3881 48.2.68. Partition Sur face Dialog Box......................................................................................3885 48.2.69. Partitioning and L oad B alancing D ialog Box..............................................................3887 48.2.70. Pathlines D ialog Box.................................................................................................3891 48.2.71. Plane Sur face Dialog Box..........................................................................................3895 48.2.72. Point Sur face Dialog Box...........................................................................................3898 48.2.73. Quadr ic Sur face Dialog Box.......................................................................................3899 48.2.74. Reduc ed Or der M odel D ialog Box.............................................................................3901 48.2.75. Reference Frame D ialog Box......................................................................................3902 48.2.76. Region A daption D ialog Box.....................................................................................3903 48.2.77. Replac e Cell Z one D ialog Box....................................................................................3905 48.2.78. Report Definitions D ialog Box...................................................................................3906 48.2.79. Report File D efinitions D ialog Box.............................................................................3907 48.2.80. Report Plot D efinitions D ialog Box............................................................................3909 48.2.81. Residual M onit ors D ialog Box....................................................................................3910 48.2.82. Rotate Mesh D ialog Box............................................................................................3912 48.2.83. S2S Inf ormation D ialog Box.......................................................................................3913 48.2.84. Separ ate Cell Z ones D ialog Box.................................................................................3914 48.2.85. Separ ate Face Zones D ialog Box................................................................................3915 48.2.86. Set Injec tion P roperties D ialog Box...........................................................................3917 48.2.87. Set M ultiple Injec tion P roperties D ialog Box..............................................................3925 48.2.88. Shell C onduc tion La yers D ialog Box..........................................................................3926 48.2.89. Shell C onduc tion M anager D ialog Box......................................................................3927 48.2.90. Structural Point Sur face Dialog Box...........................................................................3928 48.2.91. Sur face Meshes D ialog Box.......................................................................................3929 48.2.92. Sur face Report Definition D ialog Box........................................................................3930 48.2.93. Sur faces D ialog Box..................................................................................................3933 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. lxxviiiUser's G uide48.2.94. Thread C ontrol D ialog Box........................................................................................3934 48.2.95. Transf orm Sur face Dialog Box....................................................................................3935 48.2.96. Transla te Mesh D ialog Box........................................................................................3937 48.2.97. Turbo 2D C ontours D ialog Box..................................................................................3938 48.2.98. Turbo Averaged C ontours D ialog Box........................................................................3939 48.2.99. Turbo Averaged X Y Plot D ialog Box...........................................................................3941 48.2.100. Turbo Options D ialog Box.......................................................................................3942 48.2.101. Turbo Report Dialog Box.........................................................................................3943 48.2.102. Turbo Topology Dialog Box.....................................................................................3945 48.2.103. UDF Libr ary Manager D ialog Box.............................................................................3946 48.2.104. User-D efined F an M odel D ialog Box........................................................................3947 48.2.105. User-D efined F unction H ooks D ialog Box................................................................3948 48.2.106. User-D efined M emor y Dialog Box...........................................................................3951 48.2.107. User D efined R eport Definition D ialog Box..............................................................3951 48.2.108. User-D efined Sc alars D ialog Box..............................................................................3953 48.2.109. Vectors D ialog Box..................................................................................................3954 48.2.110. Volume A daption D ialog Box...................................................................................3956 48.2.111. Volume R eport Definition D ialog Box......................................................................3958 48.2.112. Warning D ialog Box................................................................................................3960 48.2.113. Yplus/Ystar A daption D ialog Box.............................................................................3961 48.2.114. Zone Sur face Dialog Box.........................................................................................3962 A. ANSY S Fluen t Model C ompa tibilit y................................................................................................3965 B. ANSY S Fluen t File F ormats.............................................................................................................3969 B.1. Case and D ata File F ormats....................................................................................................3969 B.1.1. Guidelines ....................................................................................................................3969 B.1.2. Formatting C onventions in B inar y and F ormatted F iles..................................................3969 B.1.3. Grid Sections ................................................................................................................3970 B.1.3.1. Commen t............................................................................................................3970 B.1.3.2. Header ................................................................................................................3971 B.1.3.3. Dimensions .........................................................................................................3971 B.1.3.4. Nodes ..................................................................................................................3971 B.1.3.5. Periodic S hado w Faces.........................................................................................3972 B.1.3.6. Cells ....................................................................................................................3973 B.1.3.7. Faces...................................................................................................................3974 B.1.3.8. Face Tree.............................................................................................................3976 B.1.3.9. Cell Tree...............................................................................................................3977 B.1.3.10. Interface Face Parents........................................................................................3977 B.1.3.11. Example F iles .....................................................................................................3978 B.1.3.11.1. Example 1 .................................................................................................3978 B.1.3.11.2. Example 2 .................................................................................................3979 B.1.3.11.3. Example 3 .................................................................................................3980 B.1.4. Other (N on-G rid) C ase S ections ....................................................................................3981 B.1.4.1. Zone ...................................................................................................................3981 B.1.4.2. Partitions .............................................................................................................3983 B.1.5. Data Sections ...............................................................................................................3984 B.1.5.1. Grid Size..............................................................................................................3984 B.1.5.2. Data Field ............................................................................................................3984 B.1.5.3. Residuals .............................................................................................................3985 B.2. Mesh M orpher/Optimiz er File F ormats...................................................................................3986 B.3. Shell C onduc tion S ettings F ile F ormat...................................................................................3987 B.4. 3D F an C urve File F ormat.......................................................................................................3987 C. Controlling CHEMKIN-CFD S olver Paramet ers U sing Text Commands ..............................................3989 lxxixRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uideC.1. Advanced P aramet ers U sed in the S teady-State Solution A lgor ithm .......................................3993 C.2. Setting U p M onit or C ells f or the ANSY S CHEMKIN-CFD C hemistr y Solver................................3994 C.3. Diagnostic F iles and E rror M essages ......................................................................................3994 C.4. Error M essages P rinted in the ANSY S Fluen t Graphic al User In terface.....................................3996 C.5. Diagnostic M essages in the KINetics-log.txt File.........................................................3998 D. Nomencla ture...............................................................................................................................4001 Biblio graph y.....................................................................................................................................4005 IV. Applic ation C lien ts...........................................................................................................................4015 1. Remot e Visualiza tion and A ccessing F luen t Remot ely...............................................................4017 1.1. Starting R emot e Visualiza tion ................................................................................................4017 1.1.1. Steps f or S tarting the S erver.........................................................................................4017 1.1.1.1. Port Managemen t................................................................................................4018 1.1.2. Steps F or Starting the R emot e Visualiza tion C lient.........................................................4018 1.2. Using a J ob Scheduler with R emot e Visualiza tion ...................................................................4020 1.3. Operating in the F luen t Remot e Visualiza tion En vironmen t....................................................4020 1.3.1. Adding N ew R emot e Client Connec tions .......................................................................4020 1.3.2. Initializing , Starting , Pausing , and In terrupting the C alcula tion .......................................4021 1.3.3. Modifying S olution S ettings .........................................................................................4022 1.3.4. Graphics O bjec ts..........................................................................................................4024 1.3.4.1. Creating and D ispla ying G raphics objec ts.............................................................4024 1.3.4.2. Modifying the Views............................................................................................4025 1.3.4.3. Synchr onizing with the S erver..............................................................................4026 1.3.5. Messaging and Text Commands ....................................................................................4026 1.3.6. Saving C ase and D ata Files............................................................................................4028 1.3.7. Disconnec ting the S erver and C lient.............................................................................4029 1.3.7.1. Disconnec ting fr om Within the R emot e Client Session ..........................................4029 1.3.7.2. Disconnec ting fr om Within the R emot e Server Session .........................................4029 1.4. Python, Scripting and Transcr ipts in the R emot e Client...........................................................4030 1.4.1. Python Scr ipting ..........................................................................................................4030 1.4.2. Starting and S topping a Transcr ipt................................................................................4032 1.5. Remot e Visualiza tion B est P ractices.......................................................................................4032 1.6. Remot e Visualiza tion C lient En vironmen t Variables ................................................................4033 1.7. Limita tions ............................................................................................................................4034 2. Fluen t Icing ..................................................................................................................................4037 2.1. Overview of F luen t Icing .......................................................................................................4037 2.2. Quick S tart............................................................................................................................4038 2.3. Launching F luen t Icing ..........................................................................................................4039 2.4. Fluen t Icing G raphic al U ser In terface La yout ..........................................................................4040 2.5. Creating a F luen t Icing S imula tion .........................................................................................4044 2.5.1. Case F ile R equir emen ts.................................................................................................4044 2.5.2. Loading a C ase F ile.......................................................................................................4044 2.5.2.1. Opening a C ase F ile.............................................................................................4045 2.5.2.2. Imp orting a C ase F ile...........................................................................................4047 2.6. Setting-U p a F luen t Icing S imula tion ......................................................................................4048 2.6.1. Set-up ..........................................................................................................................4048 2.6.1.1. Airflow................................................................................................................4050 2.6.1.2. Particles ...............................................................................................................4055 2.6.1.3. Ice.......................................................................................................................4062 2.6.2. Boundar y Conditions ....................................................................................................4064 2.6.2.1. Inlet Types...........................................................................................................4065 2.6.2.2. Wall.....................................................................................................................4072 2.6.2.3. Outlet Types........................................................................................................4075 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. lxxxUser's G uide2.6.3. Solve............................................................................................................................4076 2.6.3.1. Airflow................................................................................................................4077 2.6.3.2. Particles ...............................................................................................................4080 2.6.3.3. Ice.......................................................................................................................4084 2.6.3.4. Multi-S hot ...........................................................................................................4086 2.6.4. Results .........................................................................................................................4087 2.6.4.1. Quick-V iew ..........................................................................................................4090 2.6.4.2. Viewmer ical ........................................................................................................4093 2.6.4.3. CFD-P ost.............................................................................................................4094 2.6.5. Preferences..................................................................................................................4094 2.6.6. Advanced S ettings .......................................................................................................4095 2.6.7. File Types.....................................................................................................................4096 2.6.8. Appendix .....................................................................................................................4099 2.6.8.1. Python C ommands ..............................................................................................4099 2.6.8.2. Fluen t Journal C ommands ...................................................................................4101 lxxxiRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uideRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. lxxxiiList of F igur es 1.1. ANSY S Fluen t Architecture......................................................................................................................4 4.1.The G ener al Options Tab of F luen t Launcher ..........................................................................................37 4.2.The P arallel S ettings Tab of F luen t Launcher ..........................................................................................40 4.3.The R emot e Tab of F luen t Launcher .......................................................................................................42 4.4.The Scheduler Tab of F luen t Launcher ( Windo ws 64 Version) ..................................................................43 4.5.The En vironmen t Tab of F luen t Launcher ...............................................................................................44 4.6.The B atch Options D ialog Box...............................................................................................................58 8. Cell Types................................................................................................................................................64 3.1.The U ser In terface Comp onen ts............................................................................................................75 3.2.The Watertigh t Geometr y Workflow ......................................................................................................81 3.3.The Outline View Tree...........................................................................................................................82 3.4. Model L evel M enu ................................................................................................................................82 3.5. CAD A ssemblies Tree.............................................................................................................................83 3.6. CAD A ssemblies M enu ..........................................................................................................................83 3.7. CAD C omp onen t/Body Level M enu .......................................................................................................84 3.8. CAD Lab el Level M enu ..........................................................................................................................84 3.9. Global O bjec t Level M enu .....................................................................................................................85 3.10. Individual O bjec t Level M enu ..............................................................................................................86 3.11. Face Zone Lab els L evel M enu ..............................................................................................................87 3.12. Individual Lab el M enu .........................................................................................................................88 3.13. Unreferenced Z ones M enu ..................................................................................................................88 3.14. Preferences D ialog Box........................................................................................................................96 5.1. Splitting the F ace of a C oiled G eometr y...............................................................................................119 5.2. Imp orted C oiled G eometr y.................................................................................................................119 6.1. Example of a S elf-In tersec tion: Double F aces A ppear When S hare Topology is N ot Enabled ...................137 6.2. Example of a S elf-In tersec tion: Local M esh S ize is S ignific antly Lar ger Than the P ipe Thick ness ..............137 6.3. Showing M arked G aps ........................................................................................................................142 6.4. Applying S hare Topology to M arked G aps ...........................................................................................143 6.5. Incomplet e Gap M arking (M ax G ap D istanc e = 0.12) ............................................................................143 6.6. Complet e Gap M arking (M ax G ap D istanc e = 0.15) ...............................................................................143 6.7. Excessiv e Gap M arking A round a Washer (M ax G ap D istanc e = 1.2) ......................................................144 6.8. Proper G ap M arking A round a Washer (M ax G ap D istanc e = 0.8) ..........................................................144 6.9. Example of a S ingle Sur face Cap with M ultiple F aces............................................................................145 6.10. Example of a S ingle Sur face Cap with M ultiple F aces..........................................................................145 6.11. Example of an A nnular C ap Type.......................................................................................................146 6.12. Example of a P roblema tic Tilted A nnular Op ening ..............................................................................146 6.13. Example of a S elf-In tersec tion: Additional C ap In tersec ts With O ther Sur faces.....................................147 6.14. Example of a F luid and a S olid Volume M esh ......................................................................................152 6.15. A C AD F ile L oaded in to the C AD M odel Tree.......................................................................................160 6.16. Selec ted P ortions of a C AD F ile L oaded in to the M eshing M odel Tree.................................................162 6.17. Properties of a S elec ted C ustom M eshing M odel O bjec t....................................................................164 6.18. Faceting Example ..............................................................................................................................167 6.19. Example of a S elf-In tersec tion: Additional C ap In tersec ts With O ther Sur faces.....................................171 6.20. An Example of an Ex ternal F low Boundar y.........................................................................................171 6.21. An Ex ternal F low Bounding B ox.........................................................................................................172 6.22. An Ex ternal F low Boundar y Around a C ar...........................................................................................173 6.23. An Example of a R efinemen t Region A round a C ar.............................................................................173 6.24. An Example of M ultiple R efinemen t Regions A round a C ar.................................................................176 6.25. An Example of M ultiple R efinemen t Regions A round a Vehicle ...........................................................176 6.26. An Example of A ddressing S harp Angles - C AD G eometr y..................................................................180 lxxxiiiRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.6.27. An Example of A ddressing S harp Angles - F inal M esh .........................................................................181 6.28. Sharp Angles With and Without the Z ones S epar ated B y Face............................................................181 6.29. An Example of a P orous R egion .........................................................................................................184 6.30. An Example of a P orous R egion: Fins and Tubes in a H eat Exchanger ...................................................185 6.31. The P oints of a P orous R egion ............................................................................................................185 6.32. The B uffer Size for a P orous R egion ....................................................................................................186 6.33. Iden tifying a F luid R egion in the Wake Behind a C ar...........................................................................187 6.34. Iden tifying P otential L eakages Within a C ar........................................................................................189 8.1. Use of C urvature Sizing .......................................................................................................................209 8.2. Use of P roximit y Sizing ........................................................................................................................210 8.3. Use of the F ace Boundar y Option f or Face Proximit y............................................................................211 8.4. Use of the Ignor e Or ientation Option f or Face Proximit y.......................................................................212 8.5. Use of M eshed S izing ..........................................................................................................................213 8.6. Use of S oft Sizing ................................................................................................................................214 8.7. Use of B ody of Influenc e Sizing ............................................................................................................215 8.8. Contours of S ize..................................................................................................................................220 8.9. Displa y of M esh S ize Based on S ize Field ..............................................................................................220 9.1. Mesh With D ifferent Cell Z one Types....................................................................................................225 9.2. Use of the O bjec t Priority for O verlapping O bjec ts...............................................................................225 9.3. Creating O bjec ts—Example ................................................................................................................226 9.4. Objec ts D efined U sing the Subtr act Metho d........................................................................................226 9.5. Using M aterial P oints—Example ..........................................................................................................235 9.6. Example—C utCell M esh, Only O bjec ts D efined ....................................................................................236 9.7. Example—F luid Sur face Ex tracted F rom G eometr y Objec ts and M aterial P oint.....................................237 10.1. Closing a R adial G ap..........................................................................................................................242 10.2. Creating a Sur face Using an E dge ......................................................................................................244 10.3. Creating a Sur face Using N odes .........................................................................................................245 10.4. Overlapping Sur faces........................................................................................................................252 10.5. Connec ted Sur faces A fter Join...........................................................................................................252 10.6. Intersec ting Sur faces.........................................................................................................................253 10.7. Connec ted Sur faces A fter In tersec t....................................................................................................253 10.8. Orientation of N ormals in G ap...........................................................................................................257 10.9. Remo ving G aps B etween O bjec ts—F ace-Face Option ........................................................................258 10.10. Remo ving G aps B etween O bjec ts—F ace-Edge Option .....................................................................258 10.11. Gap and Thick ness C onfigur ations ...................................................................................................259 10.12. Remo ving Thick ness in O bjec ts........................................................................................................260 10.13. Mesh O bjec ts to be Connec ted........................................................................................................261 10.14. Mesh O bjec t Created b y Sewing ......................................................................................................261 12.1. Free N odes ........................................................................................................................................274 12.2. Example of a Thin Wall.......................................................................................................................274 12.3. Intersec tion of B oundar y Zones .........................................................................................................275 12.4. Intersec tion (A) Without and (B) With the R efine Option .....................................................................275 12.5. Partially O verlapping F aces...............................................................................................................276 12.6. Joining of O verlapping F aces.............................................................................................................277 12.7. Remeshing of J oined F aces................................................................................................................277 12.8. Nearest P oint Projec tion f or S titching ................................................................................................278 12.9. Sur faces B efore Stitch........................................................................................................................278 12.10. Sur faces A fter Stitch........................................................................................................................279 12.11. Refining a Triangular B oundar y Face................................................................................................290 12.12. Boundar y Mesh (A) B efore and (B) A fter Refining B ased on P roximit y................................................291 12.13. Sur face Mesh - F eature Angle = 60 ...................................................................................................293 12.14. Edge Z one f or Face Zone A pproach and F ixed A ngle = 65 ................................................................293 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. lxxxivUser's G uide12.15. Edge Z ones f or Face Zone A pproach and F ixed A ngle = 55 (or A daptiv e Angle) .................................294 12.16. Edge Z one f or Face Seed A pproach and F ixed A ngle = 65 .................................................................294 12.17. Edge Z ones f or Face Seed A pproach and F ixed A ngle = 55 (or A daptiv e Angle) .................................295 12.18. Mesh (A) B efore and (B) A fter U sing the F aceted S titch Option ..........................................................302 12.19. Triangula ting a B oundar y Zone ........................................................................................................303 12.20. Face Separ ation B ased on R egion ....................................................................................................305 12.21. Face Separ ation B ased on C ell N eighb or..........................................................................................305 12.22. Planar P oints M etho d......................................................................................................................312 12.23. Cylinder D efined b y 3 A rc Nodes, Radial G ap, and A xial D elta ............................................................314 12.24. Cylinder D efined b y 3 A rc Nodes and a H eigh t Node........................................................................315 12.25. Cylinder D efined b y Axial P oints and R adii .......................................................................................316 12.26. Loop S elec tion Toolbar ....................................................................................................................323 13.1. Schema tic R epresen tation of Wrapping P rocess.................................................................................326 13.2. Individual O bjec t Loop......................................................................................................................329 13.3. Collec tive Objec t Loops .....................................................................................................................330 13.4. Overlaid G eometr y Clipp ed with the P an P lane ..................................................................................333 13.5. Leak D etection U sing the P an R egions D ialog Box..............................................................................333 13.6. Wrapping Individual O bjec ts.............................................................................................................336 13.7. Multiple S olids ..................................................................................................................................336 13.8. Single S olid Sur face...........................................................................................................................337 13.9. Extracting the F low Volume ...............................................................................................................337 14.1. Possible M esh C ell S hap es.................................................................................................................342 14.2. Mesh with P risms in a B oundar y La yer Region ....................................................................................343 14.3. Sur face Mesh C ontaining Only Tetrahedr a.........................................................................................343 14.4. Sur face Mesh ....................................................................................................................................343 14.5. Hexcore Mesh ...................................................................................................................................344 14.6. CutCell M esh .....................................................................................................................................345 14.7. Extending an Existing Tetrahedr al M esh U sing P risms ........................................................................345 14.8. Example of a N on-C onformal In terface..............................................................................................346 14.9. Mesh G ener ated U sing I sola ted N odes t o Concentrate Cells ...............................................................348 14.10. Mesh G ener ated Without U sing I sola ted N odes ................................................................................348 14.11. Pyramid C ell—T ransition fr om a H exahedr on t o a Tetrahedr on.........................................................353 14.12. Pyramid C ells In tersec ting E ach O ther and B oundar y.......................................................................356 14.13. Fixed In tersec ting P yramid C ells U sing Triangular F aces....................................................................356 14.14. Creating the H eat Exchanger M esh ..................................................................................................358 14.15. The Thread C ontrol D ialog Box.........................................................................................................365 15.1. Prism S hap es....................................................................................................................................367 15.2. Layer H eigh ts Comput ed U sing the F our G rowth M etho ds.................................................................371 15.3. Different Growth P aramet ers on A djac ent Zones ................................................................................374 15.4. Different Growth P aramet ers on N onadjac ent Zones—U sing the A uto Mesh Option ...........................376 15.5. Prism G rowth on a D angling Wall.......................................................................................................377 15.6. Ignor ing In valid N ormals ...................................................................................................................377 15.7. Collision of P rism La yers....................................................................................................................378 15.8. Prism La yers S hrunk t o Avoid C ollision ...............................................................................................379 15.9. Ignor ing A reas of P roximit y...............................................................................................................380 15.10. Uniform O ffset D istanc e Metho d.....................................................................................................382 15.11. Minimum-H eigh t Offset D istanc e Metho d.......................................................................................382 15.12. Last R atio M etho d...........................................................................................................................383 15.13. Effect of O ffset S moothing ..............................................................................................................384 15.14. Uniform D irection Vector for a S traigh t-Sided P rism R egion ..............................................................384 15.15. Normal D irection Vectors f or a C urved P rism R egion ........................................................................385 15.16. Normal D irection Vectors B efore Smoothing ....................................................................................385 lxxx vRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide15.17. Normal D irection Vectors A fter Smoothing ......................................................................................386 15.18. Effect of A djac ent Zone A ngle .........................................................................................................387 15.19. Symmetr y Zone and C ar Wall B efore Prism G ener ation .....................................................................388 15.20. Symmetr y Zone and C ar Wall A fter Prism G ener ation Without R etriangula tion ..................................388 15.21. Symmetr y Zone and C ar Wall A fter Prism G ener ation and R etriangula tion ........................................389 15.22. Node S moothing in R ings ................................................................................................................390 15.23. Use of M ultiple Sc oped P rism C ontrols.............................................................................................394 15.24. Stair S tepp ed P rism La yers in S harp Corner ......................................................................................395 16.1. Local Refinemen t Region f or the Tetrahedr al M esh .............................................................................409 17.1. Hexcore Mesh U sing (A) B uffer La yers = 1 (B) B uffer La yers = 2 ............................................................417 17.2. Hexcore Mesh U sing (A) P eel La yers = 0 (B) P eel La yers = 2 .................................................................417 17.3. Hexcore to the F ar-Field B oundar y.....................................................................................................419 17.4. Hexcore to Boundar ies......................................................................................................................420 17.5. Only H excore....................................................................................................................................421 17.6. Local Refinemen t Region f or the H excore Mesh .................................................................................422 20.1. Schema tic R epresen tation of the C artesian G rid Refinemen t Using S ize Functions ..............................434 20.2. Mesh A fter R efinemen t.....................................................................................................................435 20.3. Mesh A fter Projec tion ........................................................................................................................435 20.4. Cells S epar ated A fter D ecomp osition .................................................................................................436 20.5. CutCell M esh A fter B oundar y Recovery..............................................................................................437 20.6. Mesh G ener ated for G eometr y Ha ving Z ero-Thick ness B affles ............................................................440 20.7. Recovering O verlapping Sur faces......................................................................................................441 20.8. Resolving Thin R egions .....................................................................................................................442 20.9. Rezoning M ultiply C onnec ted F aces..................................................................................................443 20.10. Gener ating P risms f or the C utCell M esh ...........................................................................................445 20.11. Prism G rowth Limita tions—V olumes S haring an E dge ......................................................................446 20.12. Prism G rowth Limita tions—V olumes S haring an E dge ......................................................................446 20.13. Prism G rowth Limita tions—V olumes S haring the P rism B ase ............................................................447 21.1. 2–3 and 3–2 S wap C onfigur ations ......................................................................................................453 21.2. 4–4 S wap C onfigur ation ....................................................................................................................453 21.3. Sliver Formation ................................................................................................................................454 21.4. Movemen t of B oundar y Nodes ..........................................................................................................460 21.5. Cavity Around a M irror R emeshed With Tetrahedr a............................................................................463 21.6. Cavity Around a M irror R emeshed With H excore Mesh .......................................................................465 21.7. Copying and Transla ting a C ell Z one ..................................................................................................467 21.8. The S elec tive Mesh C heck D ialog.......................................................................................................470 22.1. Mesh D ispla y (A) With S hrink F actor = 0 (B) With S hrink F actor = 0.01 ..................................................478 22.2. Camer a Definition .............................................................................................................................483 22.3. Graphics D ispla y with B ounding F rame ..............................................................................................485 23.1. Ideal and S kewed Triangles and Q uadr ilaterals...................................................................................495 23.2. Vectors U sed t o Comput e Or tho S kew/In verse Or thogonal Q ualit y for a C ell.......................................499 23.3. Vectors U sed t o Comput e Or tho S kew Q ualit y for a F ace....................................................................500 23.4. Calcula ting the F luen t Aspect Ratio f or a U nit C ube............................................................................501 1. Quadr ilateral M esh ................................................................................................................................523 2. Quadr ilateral M esh with P eriodic B oundar ies.........................................................................................524 3. Quadr ilateral M esh with Hanging N odes ................................................................................................525 1.1.The GUI C omp onen ts..........................................................................................................................550 1.2.The F luen t Ribbon...............................................................................................................................550 1.3.The F luen t Outline View ......................................................................................................................551 1.4. Graphics Windo w Context Menu: Single-S elec tion ...............................................................................553 1.5. Graphics Windo w Context Menu: Multiple-S elec tion ............................................................................554 1.6. Displa ying Two Graphics Windo ws......................................................................................................555 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. lxxx viUser's G uide1.7.The S tandar d Toolbar ..........................................................................................................................556 1.8.The G raphics Toolbar ...........................................................................................................................557 1.9.The P ointer Tools.................................................................................................................................557 1.10. The View Tools..................................................................................................................................558 1.11. The P rojec tion Tools..........................................................................................................................558 1.12. Mesh D ispla y Configur ation ..............................................................................................................559 1.13. Additional D ispla y Options ................................................................................................................560 1.14. The S elec t File D ialog Box for Windo ws..............................................................................................570 1.15. The S elec t File D ialog Box for Linux P latforms....................................................................................571 1.16. Another Version of the S elec t File D ialog Box for Linux P latforms........................................................571 1.17. Preferences D ialog Box......................................................................................................................574 1.18. Fluen t GUI in Japanese ......................................................................................................................575 3.1.The S elec t File D ialog Box....................................................................................................................582 3.2.The A utosave Dialog Box.....................................................................................................................591 3.3.The Write Profile D ialog Box.................................................................................................................595 3.4. Multiple S elec tion of J ournal F iles .......................................................................................................600 3.5.The Imp ort Menu ................................................................................................................................603 3.6.The Exp ort Dialog Box.........................................................................................................................613 3.7.The Exp ort Particle Hist ory Data D ialog Box.........................................................................................626 3.8.The C alcula tion A ctivities Task P age .....................................................................................................628 3.9.The A utoma tic Exp ort Dialog Box........................................................................................................629 3.10. The A utoma tic P article Hist ory Data Exp ort Dialog Box.......................................................................631 3.11. The Exp ort to CFD-P ost D ialog Box....................................................................................................633 3.12. The S olution F iles D ialog Box.............................................................................................................636 3.13. The In terpolate Data D ialog Box........................................................................................................637 3.14. The Volume FSI M apping D ialog Box for C ell Z one D ata......................................................................642 3.15. The Sur face FSI M apping D ialog Box for Face Zone D ata.....................................................................642 3.16. The S ave Picture Dialog Box...............................................................................................................646 3.17. The D ata File Q uantities D ialog Box...................................................................................................652 4.1.The S et U nits D ialog Box.....................................................................................................................656 4.2.The D efine U nit D ialog Box..................................................................................................................658 5.1.The Expr ession E ditor D ialog Box.........................................................................................................666 5.2.The Expr ession D ialog Box...................................................................................................................667 5.3. Contours of Velocity - P arabolic Inflo w.................................................................................................670 5.4. Parabolic Inflo w Velocity Over Time .....................................................................................................673 5.5. Pipe Geometr y Color ed b y ID (H eated Wall is G reen) ............................................................................676 5.6. Contours of Temp erature (outlet is closest) ..........................................................................................676 5.7. Plots of Inlet Temp erature, Average Outlet Temp erature, and M aximum Outlet Temp erature.................677 6.1. Cell Types...........................................................................................................................................704 6.2. Structured Q uadr ilateral M esh f or an A irfoil.........................................................................................705 6.3. Unstr uctured Q uadr ilateral M esh ........................................................................................................705 6.4. Multiblo ck S tructured Q uadr ilateral M esh ............................................................................................706 6.5. O-T ype Structured Q uadr ilateral M esh .................................................................................................706 6.6. Parachut e Modeled With Z ero-Thick ness Wall......................................................................................706 6.7. C-Type Structured Q uadr ilateral M esh .................................................................................................707 6.8. 3D M ultiblo ck S tructured M esh ...........................................................................................................707 6.9. Unstr uctured Triangular M esh f or an A irfoil..........................................................................................707 6.10. Unstr uctured Tetrahedr al M esh .........................................................................................................708 6.11. Hybrid Triangular/Q uadr ilateral M esh with Hanging N odes ................................................................708 6.12. Non-C onformal H ybrid M esh f or a R otor-S tator G eometr y..................................................................709 6.13. Polyhedr al M esh ...............................................................................................................................709 6.14. Face and N ode N umb ering f or Triangular C ells...................................................................................710 lxxx viiRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide6.15. Face and N ode N umb ering f or Q uadr ilateral Cells ..............................................................................711 6.16. Face and N ode N umb ering f or Tetrahedr al Cells.................................................................................712 6.17. Face and N ode N umb ering f or Wedge C ells .......................................................................................713 6.18. Face and N ode N umb ering f or P yramidal C ells...................................................................................714 6.19. Face and N ode N umb ering f or H ex Cells ............................................................................................715 6.20. An Example of a P olyhedr al Cell.........................................................................................................716 6.21. Setup of A xisymmetr ic Geometr ies with the x A xis as the C enterline ..................................................719 6.22. The Vectors U sed t o Comput e Or thogonalit y.....................................................................................720 6.23. Calcula ting the A spect Ratio f or a U nit C ube......................................................................................721 6.24. The S elec t File D ialog Box..................................................................................................................734 6.25. The Sur face Meshes D ialog Box.........................................................................................................738 6.26. The R eference Frame D ialog Box........................................................................................................739 6.27. The M otion Tab of the R eference Frame D ialog Box............................................................................740 6.28. Point Sur face Creation on L ocal Reference Frame ...............................................................................741 6.29. Profile D efinition on L ocal Reference Frame .......................................................................................741 6.30. Complet ely O verlapping M esh In terface Intersec tion .........................................................................742 6.31. Partially O verlapping M esh In terface Intersec tion ..............................................................................742 6.32. Two-Dimensional N on-C onformal M esh In terface..............................................................................743 6.33. Non-C onformal P eriodic B oundar y Condition ( Transla tional) ..............................................................744 6.34. Non-C onformal P eriodic B oundar y Condition (R otational) ..................................................................745 6.35. Transla tional N on-C onformal In terface with the P eriodic R epeats Option ............................................746 6.36. Rotational N on-C onformal In terface with the P eriodic R epeats Option ...............................................747 6.37. Non-C onformal C oupled Wall In terfaces............................................................................................748 6.38. Matching N on-C onformal Wall In terfaces...........................................................................................749 6.39. Non-C onformal M app ed In terface with a G ap and P enetr ation ...........................................................750 6.40. A C ircular N on-C onformal In terface...................................................................................................755 6.41. The M esh In terfaces D ialog Box.........................................................................................................756 6.42. The A uto Create Options D ialog Box..................................................................................................757 6.43. The E dit M esh In terfaces D ialog Box..................................................................................................758 6.44. Contours of In terface Overlap F raction ..............................................................................................761 6.45. The C reate/Edit M esh In terfaces D ialog Box.......................................................................................763 6.46. Transf erring D isplac emen ts...............................................................................................................765 6.47. Projec ting N odes ..............................................................................................................................766 6.48. Overset C omp onen t and B ackground M esh .......................................................................................767 6.49. Solve Cells A fter Initializa tion .............................................................................................................767 6.50. Valid O verset M eshes with C omp onen ts in C lose P roximit y................................................................769 6.51. Second C omp onen t Modifying Existing B ody....................................................................................769 6.52. Existing B ody Modific ation A fter Initializa tion ....................................................................................770 6.53. Multiple C omp onen ts Bridged b y Collars M eshes ...............................................................................770 6.54. Multiple C omp onen ts with C ollar M eshes Initializ ed..........................................................................771 6.55. Adding F luid t o a R egion U sing C ut C ontrol.......................................................................................771 6.56. Cut C ontrolled R egion A fter Initializa tion ...........................................................................................772 6.57. Overset C omp onen t and B ackground M eshes B efore Hole C utting .....................................................773 6.58. Overset C omp onen t and B ackground M eshes A fter H ole C utting .......................................................773 6.59. Overset C omp onen t and B ackground M eshes A fter O verlap M inimiza tion .........................................774 6.60. Overset M esh B efore Hole C utting .....................................................................................................775 6.61. Overset M esh A fter M inimiza tion B ased on B oundar y Distanc e..........................................................775 6.62. Valid O verlap....................................................................................................................................776 6.63. Invalid O verlap C reating Or phans ......................................................................................................778 6.64. Create/Edit O verset In terfaces D ialog Box..........................................................................................782 6.65. Contours of O verset C ell Type: Background M esh ...............................................................................786 6.66. Contours of O verset C ell Type: Comp onen t Mesh ...............................................................................786 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. lxxx viiiUser's G uide6.67. The S olution M etho ds Task P age ........................................................................................................791 6.68. Connec tion of E dge C entroids with F ace Centroids ............................................................................797 6.69. A P olyhedr al Cell...............................................................................................................................797 6.70. A C onverted P olyhedr al Cell with P reser ved H exahedr al Cell S hap e....................................................798 6.71. Treatmen t of Wedge B oundar y La yers................................................................................................798 6.72. The Or iginal Tetrahedr al M esh ...........................................................................................................799 6.73. The C onverted P olyhedr al M esh ........................................................................................................799 6.74. The M erge Z ones D ialog Box.............................................................................................................803 6.75. The S epar ate Face Zones D ialog Box..................................................................................................806 6.76. Cell Z one S epar ation B ased on R egion ...............................................................................................807 6.77. The S epar ate Cell Z ones D ialog Box...................................................................................................808 6.78. The F use F ace Zones D ialog Box........................................................................................................809 6.79. The R eplac e Cell Z one D ialog Box......................................................................................................816 6.80. The D elete Cell Z ones D ialog Box.......................................................................................................817 6.81. The D eactivate Cell Z ones D ialog Box................................................................................................817 6.82. The A ctivate Cell Z ones D ialog Box....................................................................................................818 6.83. The S elec t File D ialog Box..................................................................................................................819 6.84. The A djac ency Dialog Box.................................................................................................................821 6.85. The Sc ale M esh D ialog Box................................................................................................................823 6.86. The Transla te Mesh D ialog Box..........................................................................................................825 6.87. The R otate Mesh D ialog Box..............................................................................................................826 6.88. The Impr ove Mesh D ialog Box...........................................................................................................828 6.89. Result of S moothing Op erator on N ode P osition ................................................................................829 6.90. Initial M esh B efore Smoothing Op eration ..........................................................................................829 6.91. Mesh S moothing C ausing M esh-Line C rossing ...................................................................................830 6.92. Examples of C ell C onfigur ations in the C ircle Test...............................................................................832 6.93. Swapp ed F aces to Satisfy the D elauna y Circle Test..............................................................................832 6.94. 3D F ace Swapping .............................................................................................................................833 7.1.The B oundar y Conditions Task P age ....................................................................................................837 7.2.The C opy Conditions D ialog Box..........................................................................................................841 7.3.The P aramet ers D ialog Box..................................................................................................................843 7.4.The N ew Input P aramet er/Expr ession... Selec tion .................................................................................845 7.5.The P aramet er Expr ession D ialog Box..................................................................................................846 7.6. Use Input P aramet er in Scheme P rocedur e Dialog Box.........................................................................848 7.7. Use Input P aramet er for UDF D ialog Box..............................................................................................849 7.8. Selec ting M ultiple B oundar ies f or D ispla y in the G raphics Windo w.......................................................851 7.9. Example Op erations f or M ultiple S elec ted Sur faces in the G raphics Windo w........................................852 7.10. The F luid D ialog Box..........................................................................................................................855 7.11. Rotation S pecified in the A bsolut e Reference Frame ..........................................................................857 7.12. Rotation S pecified R elative to a M oving Z one ....................................................................................858 7.13. The S olid D ialog Box..........................................................................................................................860 7.14. Single R otating S olid Z one ................................................................................................................861 7.15. Rotating solid z one separ ated fr om another fluid or solid z one separ ated b y a sur face of r evolution. .................................................................................................................................................................862 7.16. Multiple r otating solid z ones ha ving the same ma terial and motion sp ecific ations , separ ated b y mesh interfaces or c oupled w alls........................................................................................................................862 7.17. Rotating solid with b oundar ies which ar e not tangen tial t o the motion. .............................................863 7.18. Two solids in c ontact with some squish. At the c ontact, the r otational motion has some nor mal c om- ponen t, so the solv er will not achie ve global ener gy conser vation. However, the t emp erature field migh t still be acc eptable f or engineer ing pur poses ....................................................................................................863 7.19. The F luid D ialog Box for a P orous Z one ..............................................................................................874 7.20. Cone Half A ngle ................................................................................................................................877 lxxxixRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide7.21. The H eat Transf er Settings G roup B ox of the F luid D ialog Box.............................................................885 7.22. The F luid D ialog Box: Relative Permeabilit y........................................................................................888 7.23. The Table Input D ialog Box for R elative Permeabilit y..........................................................................889 7.24. Skjae veland C orrelation B ehavior [117] .............................................................................................893 7.25. The Table F ile M anager D ialog Box.....................................................................................................895 7.26. The Table Input D ialog Box for C apillar y Pressur e...............................................................................896 7.27. The F luid D ialog Box for a 3D F an Z one ..............................................................................................902 7.28. The Inflec tion P oint Ratio of a P itched B lade Turbine ..........................................................................903 7.29. Fixing Values f or the F low in a S tirred Tank .........................................................................................905 7.30. Defining a S ource for a Tiny Inlet .......................................................................................................909 7.31. The P ressur e Inlet D ialog Box.............................................................................................................921 7.32. Cylindr ical Velocity Comp onen ts in 3D , 2D, and A xisymmetr ic Domains ..............................................925 7.33. The Velocity Inlet D ialog Box..............................................................................................................930 7.34. The M ass-F low Inlet D ialog Box.........................................................................................................936 7.35. The M ass-F low Outlet D ialog Box.......................................................................................................943 7.36. The Inlet Vent Dialog Box...................................................................................................................948 7.37. The In take Fan D ialog Box.................................................................................................................950 7.38. The P ressur e Outlet D ialog Box..........................................................................................................952 7.39. Pressur es a t the F ace of a P ressur e Outlet B oundar y...........................................................................957 7.40. The P ressur e Outlet D ialog Box with the Target M ass F low Rate Option Enabled .................................959 7.41. The P ressur e Far-Field D ialog Box......................................................................................................961 7.42. Choic e of the Outflo w Boundar y Condition L ocation ..........................................................................965 7.43. The Outflo w D ialog Box.....................................................................................................................966 7.44. The Outlet Vent Dialog Box................................................................................................................968 7.45. The Exhaust F an D ialog Box...............................................................................................................970 7.46. The Wall D ialog Box for a M oving Wall................................................................................................973 7.47. The Wall D ialog Box for Specified S hear ..............................................................................................976 7.48. The Wall D ialog Box for the S pecular ity Coefficien t.............................................................................977 7.49. The Wall D ialog Box for M arangoni S tress...........................................................................................978 7.50. Downw ard Shift of the L ogarithmic Velocity Profile ............................................................................980 7.51. Illustr ation of E quiv alen t Sand-G rain R oughness ................................................................................981 7.52. The Wall D ialog Box for High Roughness (Icing) Models ...................................................................983 7.53. The Wall D ialog Box (Thermal Tab).....................................................................................................985 7.54. A Thin Wall........................................................................................................................................987 7.55. Uncoupled Thin Walls........................................................................................................................989 7.56. 2D In terface with P enetr ation and G aps .............................................................................................992 7.57. The Wall D ialog Box for Species B oundar y Condition Input .................................................................993 7.58. Use of S ymmetr y to Model One Q uarter of a 3D D uct.........................................................................998 7.59. Use of S ymmetr y to Model One Q uarter of a C ircular C ross-S ection ....................................................998 7.60. Inappr opriate Use of S ymmetr y.........................................................................................................999 7.61. Use of P eriodic B oundar ies t o Define S wirling F low in a C ylindr ical Vessel .........................................1000 7.62. Example of Transla tional P eriodicit y - P hysical D omain .....................................................................1000 7.63. Example of Transla tional P eriodicit y - M odeled D omain ...................................................................1001 7.64. The P eriodic D ialog Box...................................................................................................................1001 7.65. Use of an A xis B oundar y as the C enterline in an A xisymmetr ic Geometr y..........................................1002 7.66. The F an D ialog Box..........................................................................................................................1004 7.67. Polynomial P rofile D ialog Box for P ressur e Jump D efinition ..............................................................1005 7.68. A Fan L ocated In a 2D D uct..............................................................................................................1007 7.69. The R adia tor D ialog Box..................................................................................................................1011 7.70. Polynomial P rofile D ialog Box for Loss C oefficien t Definition ............................................................1013 7.71. A Simple D uct with a R adia tor.........................................................................................................1013 7.72. The P orous J ump D ialog Box...........................................................................................................1017 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. xcUser's G uide7.73. The M ulti E dit Velocity Inlet D ialog Box............................................................................................1020 7.74. Mesh and P rescr ibed B oundar y Conditions in a 3D A xial F low Problem .............................................1023 7.75. Mesh and P rescr ibed B oundar y Conditions in a 3D R adial F low Problem ...........................................1023 7.76. Mesh and P rescr ibed B oundar y Conditions in a 2D C ase ...................................................................1024 7.77. Prescr ibed Inlet A ngles ....................................................................................................................1027 7.78. The L ocal Or thogonal C oordina te System on to which E uler E qua tions ar e Recasted for the G ener al NRBC M etho d.........................................................................................................................................1033 7.79. Waves Leaving and En tering a B oundar y Face on Inflo w and Outflo w Boundar ies.The Wave Amplitudes are Shown with the A ssociated E igen values f or a Subsonic F low Condition ..............................................1034 7.80. The P ressur e Outlet D ialog Box With the N on-R eflec ting B oundar y Enabled ......................................1036 7.81. The Inlet , Fan, and P ressur e Outlet Z ones f or a C ircular F an Op erating in a C ylindr ical D omain ...........1045 7.82. The U ser-D efined F an M odel D ialog Box..........................................................................................1046 7.83. The F an D ialog Box..........................................................................................................................1049 7.84. Transv erse Velocities a t the S ite of the F an........................................................................................1050 7.85. Static P ressur e Jump A cross the F an.................................................................................................1051 7.86. The P rofiles D ialog Box....................................................................................................................1058 7.87. Example of U sing P rofiles as B oundar y Conditions ...........................................................................1059 7.88. The Or ient Profile D ialog Box...........................................................................................................1060 7.89. Scalar P rofile a t the Outlet ...............................................................................................................1062 7.90. Problem S pecific ation .....................................................................................................................1064 7.91. The R eplic ate Profile D ialog Box.......................................................................................................1065 7.92. The 1D S imula tion Libr ary Dialog Box..............................................................................................1072 7.93. Using GT-PO WER D ata for B oundar y Conditions ..............................................................................1073 7.94. Cell Z one C onditions f or Torque-S peed C oupling with GT-PO WER ....................................................1074 7.95. The 1D S imula tion Libr ary Dialog Box with WAVE S elec ted...............................................................1076 7.96. Using WAVE D ata for B oundar y Conditions .......................................................................................1077 8.1.The M aterials Task P age .....................................................................................................................1082 8.2.The M aterials B ranch in the Outline View..........................................................................................1083 8.3. Fluen t Database M aterials D ialog Box................................................................................................1085 8.4. Open D atabase D ialog Box................................................................................................................1088 8.5. User-D efined D atabase M aterials D ialog Box......................................................................................1089 8.6. New M aterial N ame D ialog Box.........................................................................................................1090 8.7. Copy Case M aterial D ialog Box..........................................................................................................1091 8.8. User-D efined D atabase M aterials D ialog Box: Blank ............................................................................1092 8.9. Material P roperties D ialog Box: Blank .................................................................................................1093 8.10. Edit P roperty Metho ds D ialog Box...................................................................................................1094 8.11. The P olynomial P rofile D ialog Box....................................................................................................1096 8.12. The P iecewise-Linear P rofile D ialog Box...........................................................................................1097 8.13. Piecewise-Linear D efinition of Viscosity as a F unction of Temp erature...............................................1097 8.14. The P iecewise-P olynomial P rofile D ialog Box....................................................................................1098 8.15. Compr essible Liquid M aterials S etting .............................................................................................1102 8.16. Compr essible Liquid D ensit y Settings P anel .....................................................................................1103 8.17. Variation of Viscosity with S hear R ate According t o the C arreau M odel.............................................1114 8.18. The C arreau M odel D ialog Box.........................................................................................................1115 8.19. Variation of S hear S tress with S hear R ate According t o the H erschel-B ulkley Model...........................1116 8.20. The C reate/Edit M aterials D ialog Box...............................................................................................1118 8.21. The A nisotr opic C onduc tivit y Dialog Box.........................................................................................1122 8.22. The B iaxial C onduc tivit y Dialog Box.................................................................................................1123 8.23. The Or thotr opic C onduc tivit y Dialog Box.........................................................................................1124 8.24. The C ylindr ical Or thotr opic C onduc tivit y Dialog Box........................................................................1125 8.25. Unaligned P rincipal A xes.................................................................................................................1127 8.26. The A nisotr opic C onduc tivit y - P rincipal C omp onen ts D ialog Box.....................................................1128 xciRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide8.27. The UDS D iffusion C oefficien ts D ialog Box.......................................................................................1130 8.28. The A nisotr opic UDS D iffusivit y Dialog Box......................................................................................1132 8.29. The Or thotr opic UDS D iffusivit y Dialog Box......................................................................................1133 8.30. The C ylindr ical Or thotr opic UDS D iffusivit y Dialog Box.....................................................................1134 8.31. The UDS D iffusion C oefficien ts D ialog Box.......................................................................................1135 8.32. Anisotr opic S pecies D iffusion M atrix................................................................................................1144 8.33. The Thermal D iffusion C oefficien ts D ialog Box.................................................................................1145 8.34. The M ass D iffusion C oefficien ts D ialog Box for D ilute Approxima tion ...............................................1147 8.35. The M ass D iffusion C oefficien ts D ialog Box for the M ultic omp onen t Metho d....................................1148 8.36. Typic al PT D iagr am of a P ure Material..............................................................................................1155 8.37. Typic al PV D iagr am of a P ure Material..............................................................................................1156 8.38. The C ubic E qua tion of S tate Model f or a R eal-G as Fluid ....................................................................1165 8.39. The C ubic E qua tion of S tate Model f or a R eal-G as M ixture................................................................1167 8.40. The Op erating C onditions f or a R eal G as State..................................................................................1168 8.41. The PV D iagr am f or the C ubic E qua tion of S tate Real G as M odel.......................................................1170 9.1.The U ser-D efined Sc alars D ialog Box..................................................................................................1201 9.2.The F luid D ialog Box with Inputs f or S ource Terms f or a U ser-D efined Sc alar .......................................1202 9.3.The U ser Sc alar S ources D ialog Box....................................................................................................1203 9.4.The M aterials D ialog Box with Input f or D iffusivit y for UDS E qua tions .................................................1204 9.5.The U ser-D efined Sc alars D ialog Box for a M ultiphase F low................................................................1205 9.6. Example of P eriodic F low in a 2D H eat Exchanger G eometr y..............................................................1207 9.7.The P eriodic C onditions D ialog Box...................................................................................................1208 9.8.The P eriodic D ialog Box.....................................................................................................................1210 9.9. Periodic P ressur e Field P redic ted for Flow in a 2D H eat Exchanger G eometr y......................................1211 9.10. Rotating F low in a C avity.................................................................................................................1214 9.11. Swirling F low in a G as B urner ...........................................................................................................1215 9.12. Flow in a C onverging-D iverging N ozzle ............................................................................................1218 10.1. Single C omp onen t (Blower Wheel B lade P assage) ............................................................................1228 10.2. Multiple C omp onen t (Blower Wheel and C asing) ..............................................................................1228 10.3. Single B lade M odel with R otationally P eriodic B oundar ies................................................................1229 10.4. The F luid D ialog Box Displa ying F rame M otion Inputs ......................................................................1231 10.5. Geometr y with the R otating Imp eller ...............................................................................................1233 10.6. Absolut e Velocity Vectors................................................................................................................1235 10.7. Relative Velocity Vectors..................................................................................................................1236 10.8. The S olution Initializa tion Task P age f or M oving R eference Frames ...................................................1243 10.9. The M ixing P lanes D ialog Box..........................................................................................................1245 10.10. Frozen G ust v ariations ...................................................................................................................1250 11.1. Two Passing Trains in a Tunnel .........................................................................................................1252 11.2. Rotor-S tator In teraction (S tationar y Guide Vanes with R otating B lades) ............................................1253 11.3. Blower............................................................................................................................................1253 11.4. Initial P osition of the M eshes ...........................................................................................................1254 11.5. Rotor M esh S lides with R espect to the S tator...................................................................................1255 11.6. 2D Linear M esh In terface.................................................................................................................1255 11.7. 2D C ircular-A rc Mesh In terface........................................................................................................1256 11.8. 3D C onic al M esh In terface...............................................................................................................1256 11.9. 3D P lanar-S ector M esh In terface......................................................................................................1257 11.10. The M esh In terfaces D ialog Box.....................................................................................................1260 11.11. Lift Coefficien t Plot f or a Time-P eriodic S olution .............................................................................1262 11.12. Contours of S tatic P ressur e for the R otor-S tator Example ................................................................1263 11.13. The D ynamic M esh Task P age ........................................................................................................1267 11.14. The S moothing Tab of the M esh M etho d Settings D ialog Box.........................................................1268 11.15. The M esh S moothing P aramet ers D ialog Box.................................................................................1269 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. xciiUser's G uide11.16. The Initial M esh .............................................................................................................................1271 11.17. Valid M esh A fter 45 D egree R otation U sing D iffusion-B ased S moothing ..........................................1272 11.18. Degener ated M esh A fter 40 D egree R otation U sing S pring-B ased S moothing .................................1272 11.19. Effect of D iffusion P aramet er of 0 on In terior N ode M otion .............................................................1274 11.20. Effect of D iffusion P aramet er of 1 on In terior N ode M otion .............................................................1274 11.21. Spring-B ased S moothing on In terior N odes: Start...........................................................................1277 11.22. Spring-B ased S moothing on In terior N odes: End ............................................................................1277 11.23. Interior N odes Ex tend B eyond B oundar y (Spring C onstan t Factor = 1) ............................................1278 11.24. Interior N odes R emain Within B oundar y (Spring C onstan t Factor = 0) .............................................1278 11.25. The U ndef ormed M esh ..................................................................................................................1283 11.26. The D eformed M esh ......................................................................................................................1283 11.27. Zooming in to the U ndef ormed C omplian t Strip.............................................................................1284 11.28. Zooming in to the D eformed C omplian t Strip with B oundar y La yer Smoothing A pplied ..................1285 11.29. Dynamic La yering .........................................................................................................................1286 11.30. Results of S plitting La yer with the H eigh t-Based Option .................................................................1286 11.31. Results of S plitting La yer with the R atio-B ased Option ....................................................................1287 11.32. The La yering Tab in the M esh M etho d Settings D ialog Box.............................................................1288 11.33. Use of S liding In terfaces to Transition B etween A djac ent Cell Z ones and the D ynamic La yering C ell Zone .......................................................................................................................................................1289 11.34. The R emeshing Tab in the M esh M etho d Settings D ialog Box.........................................................1291 11.35. The R emeshing Tab in the M esh M etho d Settings D ialog Box Using the S izing F unction Option ......1292 11.36. Mesh a t the End of a D ynamic M esh S imula tion Without S izing F unctions ......................................1295 11.37. Mesh a t the End of a D ynamic M esh S imula tion With S izing F unctions ............................................1295 11.38. Sizing F unction D etermina tion a t Background M esh Vertex I..........................................................1296 11.39. Interpolating the Value of the S izing F unction ................................................................................1297 11.40. Determining the N ormaliz ed D istanc e...........................................................................................1298 11.41. Expanding C ylinder B efore Region F ace Remeshing .......................................................................1301 11.42. Expanding C ylinder A fter Region F ace Remeshing ..........................................................................1301 11.43. Volume D ecomp osition f or P rism La yers........................................................................................1302 11.44. Volume D ecomp osition f or the B ase of the P rism La yers.................................................................1303 11.45. Unstr uctured Tetrahedr al M esh B efore CutCell Z one R emeshing .....................................................1304 11.46. Mesh A fter C utCell Z one R emeshing ..............................................................................................1305 11.47. CutCell Z one R emeshing With Infla tion La yers................................................................................1305 11.48. Close-U p of 2.5D Ex truded F low M eter Pump G eometr y Before Remeshing and Laplacian S mooth- ing .........................................................................................................................................................1308 11.49. Close-U p of 2.5D Ex truded F low M eter Pump G eometr y After Remeshing and Laplacian S moothing .1309 11.50. The R emeshing Tab for the 2.5D M odel..........................................................................................1310 11.51. 2.5D Ex truded G ear P ump G eometr y.............................................................................................1311 11.52. Cross S ection of a 3D C orner ..........................................................................................................1313 11.53. The In-C ylinder Tab of the Options D ialog Box................................................................................1314 11.54. Determining the S ign of the P iston P in O ffset................................................................................1315 11.55. The In-C ylinder Output C ontrols D ialog Box...................................................................................1316 11.56. Sample Output F ile S howing Various Q uantities .............................................................................1318 11.57. A 2D In-C ylinder G eometr y............................................................................................................1319 11.58. Mesh Topology Showing the Various M esh R egions ........................................................................1320 11.59. Mesh A ssociated With the C hosen Topology..................................................................................1320 11.60. The U se of S liding In terfaces to Connec t the Exhaust Valve La yering Z one t o the R emeshing Z one ...1321 11.61. Mesh S equenc e 1..........................................................................................................................1322 11.62. Mesh S equenc e 2..........................................................................................................................1323 11.63. Mesh S equenc e 3..........................................................................................................................1323 11.64. Mesh S equenc e 4..........................................................................................................................1324 11.65. Mesh S equenc e 5..........................................................................................................................1324 xciiiRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide11.66. Mesh S equenc e 6..........................................................................................................................1325 11.67. Piston P osition (m) as a F unction of C rank A ngle (deg) ...................................................................1326 11.68. Intake and Exhaust Valve Lif t (m) as a F unction of C rank A ngle (deg) ...............................................1327 11.69. Definition of Valve Zone A ttribut es (In take Valve)...........................................................................1328 11.70. The S ix DOF Tab of the Options D ialog Box.....................................................................................1329 11.71. The S ix DOF P roperties D ialog Box.................................................................................................1331 11.72. A C heck Valve with One DOF Transla tion ........................................................................................1332 11.73. The Implicit U pdate Tab of the Options D ialog Box.........................................................................1333 11.74. The C ontact Detection Tab of the Options D ialog Box.....................................................................1335 11.75. The F low Controls D ialog Box........................................................................................................1336 11.76. The D ynamic M esh E vents D ialog Box............................................................................................1337 11.77. The D efine E vent Dialog Box..........................................................................................................1338 11.78. The E vents Preview D ialog Box for In-C ylinder F lows.......................................................................1339 11.79. The D efine E vent Dialog Box for the C reating S liding In terface Option ............................................1341 11.80. Boundar y Zone B efore Inser tion ....................................................................................................1343 11.81. Boundar y Zone A fter Inser tion .......................................................................................................1343 11.82. Interior Z one B efore Inser tion ........................................................................................................1344 11.83. Interior Z one A fter Inser tion ..........................................................................................................1344 11.84. The D ynamic M esh Z ones D ialog Box for a S tationar y Zone ............................................................1347 11.85. The D ynamic M esh Z ones D ialog Box for a C utCell B oundar y Zone .................................................1349 11.86. The D ynamic M esh Z ones D ialog Box for a R igid B ody Motion ........................................................1350 11.87. Orientation C alcula tor D ialog Box..................................................................................................1352 11.88. The D ynamic M esh Z ones D ialog Box for a R igid B ody Motion U sing the S ix DOF S olver..................1353 11.89. The D ynamic M esh Z ones D ialog Box for a D eforming M otion with C ell Z one Options ....................1355 11.90. The D ynamic M esh Z ones D ialog Box for a D eforming C utCell C ell Z one .........................................1357 11.91. The C utCell B oundar y Zones Inf o Dialog Box..................................................................................1358 11.92. The D ynamic M esh Z ones D ialog Box for an In trinsic FSI Z one ........................................................1363 11.93. Solid B ody Rotation C oordina tes....................................................................................................1367 11.94. The Z one M otion D ialog Box..........................................................................................................1368 11.95. The M esh M otion D ialog Box.........................................................................................................1369 11.96. The M esh M otion D ialog Box for S teady-State Dynamic M eshes .....................................................1371 11.97. Initial O bjec t Position ....................................................................................................................1372 11.98. The M esh M otion D ialog Box After 40 U pdates...............................................................................1373 11.99. Final O bjec t Position A fter 40 Ex ecutions .......................................................................................1373 12.1. Velocity Profiles f or A xi-symmetr ic Diffuser F low (C ase CS0 – D river). Impac t of Variation of ......1380 12.2. Impac t of C hanges in on F ree M ixing La yer. Left:Velocity Profiles , Right:Turbulenc e Kinetic Ener gy Profiles ...................................................................................................................................................1380 12.3. Impac t of C hanges in on B ackward Facing J et with H eat Transf er. Left:Wall S hear S tress C oefficien t, , Right:Wall H eat Transf er C oefficien t, ..............................................................................................1381 12.4. Impac t of C hanges in on F ree Jet Flows. Left: Plane J et, Right: Round J et....................................1381 12.5. Illustr ation of SST-UR ANS v s. SST-SAS M odels ...................................................................................1386 12.6. The Viscous M odel D ialog Box.........................................................................................................1393 12.7. The Viscous M odel D ialog Box Displa ying the S palar t-Allmar as P roduction .......................................1395 12.8. The Viscous M odel D ialog Box Displa ying the S tandar d k-ε Model....................................................1397 12.9. The Viscous M odel D ialog Box Displa ying the RNG k- ε Model...........................................................1399 12.10. The Viscous M odel D ialog Box Displa ying the S tandar d k-ω Model..................................................1402 12.11. The Viscous M odel D ialog Box Displa ying the BSL k- ω Model..........................................................1404 12.12. The Viscous M odel D ialog Box Displa ying the SST k- ω Model..........................................................1405 12.13. The Viscous M odel D ialog Box with GEK O Options f or the F ull M odel .............................................1408 12.14. The Viscous M odel D ialog Box with GEK O Options f or the Wall D istanc e Free Version ......................1409 12.15. The Viscous M odel D ialog Box for the Transition SST M odel............................................................1411 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. xcivUser's G uide12.16. The In termitt ency Transition M odel in C ombina tion with the SST k- ω Model...................................1413 12.17. The Viscous M odel D ialog Box Displa ying the R eynolds S tress M odel Options .................................1415 12.18. The Viscous M odel D ialog Box Displa ying the S tress-Omega M odel Options ...................................1417 12.19. Scale-A daptiv e Simula tion (SAS) in C ombina tion with the SST Turbulenc e Model............................1418 12.20. Scale-A daptiv e Simula tion (SAS) in C ombina tion with the Transition SST M odel..............................1419 12.21. The Viscous M odel D ialog Box Displa ying Options f or DES with the S palar t-Allmar as M odel............1421 12.22. The Viscous M odel D ialog Box Displa ying Options f or DES with the R ealizable k- ε Model................1423 12.23. The Viscous M odel D ialog Box Displa ying Options f or DES with the SST k- ω Model..........................1425 12.24. The Viscous M odel D ialog Box Displa ying Options f or DES with the BSL k- ω Model..........................1427 12.25. The Viscous M odel D ialog Box Displa ying Options f or DES with the Transition SST M odel................1429 12.26. The Viscous M odel D ialog Box Displa ying the Lar ge E ddy Simula tion M odel Options ......................1431 12.27. Specifying an ELES Z one in the F luid D ialog Box.............................................................................1434 12.28. Specifying the R ANS/LES In terface.................................................................................................1435 12.29. The R ANS/LES In terface Dialog Box................................................................................................1436 12.30. The Viscous M odel D ialog Box with the SBES Options .....................................................................1446 12.31. Specifying Inlet B oundar y Conditions f or the R eynolds S tresses ......................................................1451 12.32. The S ampling Options D ialog Box..................................................................................................1466 13.1. Enabling the Ener gy Equa tion .........................................................................................................1468 13.2. Typic al Coun terflow H eat Exchanger In volving H eat Transf er Between Two Separ ated F luid S treams ..1470 13.3. The R un C alcula tion Task P age S howing S olid Time S tep...................................................................1473 13.4. The Op erating C onditions D ialog Box..............................................................................................1478 13.5. A B oundar y Wall with S hell C onduc tion ...........................................................................................1482 13.6. A Two-Sided Wall with S hell C onduc tion ..........................................................................................1483 13.7. The S hell C onduc tion M anager D ialog Box.......................................................................................1484 13.8. Shell C onduc tion La yers D ialog Box.................................................................................................1486 13.9. Shell Sur face Names f or a B oundar y Wall.........................................................................................1487 13.10. Shell Sur face Names f or a Two-Sided Wall.......................................................................................1488 13.11. The R adia tion M odel D ialog Box (DO M odel) ..................................................................................1490 13.12. The R adia tion M odel D ialog Box (N on-G ray P-1 M odel) ...................................................................1492 13.13. The DTRM R ays Dialog Box............................................................................................................1493 13.14. The R adia tion M odel D ialog Box (S2S M odel) .................................................................................1496 13.15. The View F actors and C lustering D ialog Box...................................................................................1498 13.16. The Wall D ialog Box.......................................................................................................................1500 13.17. The P articipa ting B oundar y Zones D ialog Box................................................................................1504 13.18. The Thread C ontrol D ialog Box.......................................................................................................1507 13.19. The R adia tion M odel D ialog Box (N on-G ray DO M odel) ...................................................................1511 13.20. The R adia tion M odel D ialog Box with DO/Ener gy Coupling Enabled ...............................................1512 13.21. The R adia tion M odel D ialog Box (MC) ............................................................................................1513 13.22. The Wall D ialog Box Showing R adia tion C onditions f or an Opaque Wall..........................................1517 13.23. The Wall D ialog Box Showing In ternal Emissivit y Thermal C onditions f or an Opaque Wall................1518 13.24. The Wall D ialog Box Showing Ex ternal Emissivit y and Ex ternal R adia tion Temp erature Thermal C ondi- tions .......................................................................................................................................................1519 13.25. The Wall D ialog Box for a S emi-T ranspar ent Wall B oundar y.............................................................1520 13.26. The Wall D ialog Box for an In terior S emi-T ranspar ent Wall...............................................................1522 13.27. The Wall D ialog Box for an Opaque Wall with MC M odel (G ray).......................................................1523 13.28. The Wall D ialog Box for an Opaque Wall with MC M odel (B oundar y Source)....................................1524 13.29. The Wall D ialog Box for an Opaque Wall with MC M odel (P olar D istribution with Expr ession) ...........1525 13.30. The Wall D ialog Box for an Opaque Wall with MC M odel (P olar D istribution with Table) ...................1526 13.31. The Wall D ialog Box Showing In ternal Emissivit y Thermal C onditions f or an Opaque Wall (G ray)......1527 13.32. The Wall D ialog Box for an Opaque Wall with MC M odel (N on-gr ay)................................................1528 13.33. The Wall D ialog Box Showing Ex ternal Emissivit y and Ex ternal R adia tion Temp erature Thermal C ondi- tions .......................................................................................................................................................1529 xcvRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide13.34. The S olid D ialog Box......................................................................................................................1531 13.35. The R adia tion M odel D ialog Box (DTRM) ........................................................................................1533 13.36. The DTRM G raphics D ialog Box......................................................................................................1538 13.37. Ray Displa y...................................................................................................................................1539 13.38. The S2S Inf ormation D ialog Box.....................................................................................................1540 13.39. The R adia tion M odel D ialog Box....................................................................................................1549 13.40. The R adia tion M odel D ialog Box (With S olar L oad M odel S olar R ay Tracing Option) .........................1550 13.41. The R adia tion M odel D ialog Box (with S olar L oad M odel S olar Ir radia tion Option) ...........................1551 13.42. The S olar C alcula tor D ialog Box......................................................................................................1553 13.43. The Velocity Inlet D ialog Box..........................................................................................................1555 13.44. The Wall D ialog Box.......................................................................................................................1556 13.45. The Wall D ialog Box.......................................................................................................................1557 13.46. The P orous J ump D ialog Box..........................................................................................................1558 13.47. The Wall D ialog Box Radia tion tab with S olar Ir radia tion .................................................................1560 13.48. The C ontours D ialog Box...............................................................................................................1565 13.49. The Ex ecut e Commands D ialog Box...............................................................................................1566 13.50. Temp erature Field in a 2D H eat Exchanger G eometr y With F ixed Temp erature Boundar y Condi- tions .......................................................................................................................................................1572 14.1. An Example of a F our-P ass H eat Exchanger ......................................................................................1573 14.2. Heat Exchanger M odeling Options ..................................................................................................1575 14.3. The H eat Exchanger M odel D ialog Box.............................................................................................1577 14.4. The D ual C ell H eat Exchanger D ialog Box.........................................................................................1577 14.5. The S et D ual C ell H eat Exchanger D ialog Box...................................................................................1578 14.6. The H eat Rejec tion Tab....................................................................................................................1579 14.7. The P erformanc e Data Tab...............................................................................................................1580 14.8. The H eat Transf er D ata Table D ialog Box...........................................................................................1581 14.9. The F rontal A rea Tab........................................................................................................................1582 14.10. The C oupling Tab..........................................................................................................................1583 14.11. An Example of a F our-P ass H eat Exchanger ....................................................................................1583 14.12. The H eat Exchanger M odel D ialog Box...........................................................................................1587 14.13. The U ngroup ed M acro Heat Exchanger D ialog Box Displa ying the M odel D ata Tab.........................1588 14.14. The H eat Transf er D ata Table D ialog Box for the NTU M odel............................................................1589 14.15. The U ngroup ed M acro Heat Exchanger D ialog Box Displa ying the G eometr y Tab............................1590 14.16. The U ngroup ed M acro Heat Exchanger D ialog Box Displa ying the A uxiliar y Fluid Tab.....................1591 14.17. 1x4x3 M acros................................................................................................................................1594 14.18. Mesh D ispla y With M acros.............................................................................................................1595 14.19. The C ore Porosity Model D ialog Box...............................................................................................1597 14.20. The M acro Heat Exchanger G roup D ialog Box.................................................................................1599 14.21. The H eat Transf er D ata Table D ialog Box for the NTU M odel............................................................1600 14.22. The M acro Heat Exchanger G roup D ialog Box - G eometr y Tab........................................................1601 14.23. The M acro Heat Exchanger G roup D ialog Box - A uxiliar y Fluid Tab..................................................1602 14.24. The M acro Heat Exchanger G roup D ialog Box - Supplemen tary Auxiliar y Fluid S tream Tab..............1603 14.25. The H eat Exchanger R eport Dialog Box for R eporting C omput ed H eat Rejec tion .............................1607 14.26. The H eat Exchanger R eport Dialog Box for R eporting the Inlet Temp erature...................................1608 14.27. The H eat Exchanger R eport Dialog Box for R eporting M ass F low Rate.............................................1609 14.28. The H eat Exchanger R eport Dialog Box for R eporting S pecific H eat................................................1610 14.29. The Volume R eport Definition D ialog Box.......................................................................................1611 15.1. The S pecies M odel D ialog Box.........................................................................................................1617 15.2. The S pecies M odel D ialog Box Displa ying the Thick ened F lame M odel.............................................1622 15.3. The S elec t Boundar y Species D ialog Box..........................................................................................1623 15.4. The S elec t Residual M onit ored S pecies ............................................................................................1624 15.5. The Imp ort CHEMKIN F ormat Mechanism D ialog Box for Volumetr ic Kinetics ....................................1626 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. xcviUser's G uide15.6. The M aterial D ialog Box When Imp orting CHEMKIN Transp ort Properties ..........................................1628 15.7. The C reate/Edit M aterials D ialog Box (Showing a M ixture Material)...................................................1630 15.8. The S pecies D ialog Box....................................................................................................................1631 15.9. The R eactions D ialog Box................................................................................................................1635 15.10. The Third-Body Efficienc y Dialog Box.............................................................................................1638 15.11. The P ressur e-Dependen t Reaction D ialog Box................................................................................1639 15.12. The C overage D ependen t Reaction D ialog Box...............................................................................1640 15.13. Backward Reaction P aramet ers D ialog Box.....................................................................................1641 15.14. The R eaction M echanisms D ialog Box............................................................................................1642 15.15. The S ite Paramet ers D ialog Box......................................................................................................1644 15.16. The C oal C alcula tor D ialog Box......................................................................................................1647 15.17. The Imp ort CHEMKIN F ormat Mechanism D ialog Box for Sur face Kinetics .......................................1656 15.18. The S pecies M odel D ialog Box with E lectrochemic al Reactions Enabled ..........................................1664 15.19. The R eactions D ialog Box...............................................................................................................1666 15.20. The R eaction M echanisms D ialog Box............................................................................................1668 15.21. Wall P otential B oundar y Condition ................................................................................................1669 15.22. Optimal Sur face Mesh on the R eacting C hannel Wall......................................................................1673 15.23. The R eacting C hannel M odel D ialog Box........................................................................................1674 15.24. The R eacting C hannel M odel D ialog Box (G roup Inlet C onditions Tab)............................................1676 15.25. The Wall B oundar y Condition D ialog Box for the R eacting C hannel M odel......................................1678 15.26. Reacting C hannel 2D C urves D ialog Box (Plot) ................................................................................1679 15.27. Reacting C hannel 2D C urves D ialog Box (Report)...........................................................................1680 15.28. Reactor N etwork Dialog Box (Steady-State Flow)............................................................................1682 15.29. Reactor N etwork Dialog Box - Exp ert Options .................................................................................1683 16.1. Defining E quilibr ium C hemistr y.......................................................................................................1688 16.2. Defining S teady Diffusion F lamelet C hemistr y.................................................................................1689 16.3. Defining C hemic al Boundar y Species ...............................................................................................1689 16.4. Calcula ting S teady Diffusion F lamelets ............................................................................................1690 16.5. Calcula ting the C hemistr y Look-U p Table .........................................................................................1691 16.6. The S pecies M odel D ialog Box (Chemistr y Tab).................................................................................1692 16.7. The C hemistr y Tab for the U nsteady Diffusion F lamelet M odel..........................................................1696 16.8. The Enabled D iesel U nsteady Flamelet M odel..................................................................................1699 16.9. The U nsteady Flamelet P aramet ers D ialog Box.................................................................................1700 16.10. The F lamelet F luid Z ones D ialog Box..............................................................................................1701 16.11. The S pecies M odel D ialog Box (Boundar y Tab)...............................................................................1703 16.12. The C oal C alcula tor D ialog Box......................................................................................................1712 16.13. The S pecies M odel D ialog Box (Control Tab)...................................................................................1714 16.14. The S pecies M odel D ialog Box (Control Tab) f or the S teady Diffusion F lamelet M odel......................1715 16.15. Metho d to Zero Out the S low Chemistr y Species ............................................................................1716 16.16. The S pecies M odel D ialog Box (Flamelet Tab).................................................................................1717 16.17. The F lamelet Tab for the U nsteady Diffusion F lamelet M odel..........................................................1719 16.18. The F lamelet 2D cur ves D ialog Box................................................................................................1720 16.19. The F lamelet 3D Sur faces D ialog Box.............................................................................................1721 16.20. Example 2D P lot of F lamelet D ata..................................................................................................1722 16.21. Example 3D P lot of F lamelet D ata..................................................................................................1723 16.22. The S pecies M odel D ialog Box (Table) Tab D ispla ying A utoma ted G rid Refinemen t.........................1724 16.23. The S pecies M odel D ialog Box (Table) Tab Ex cluding A utoma ted G rid Refinemen t..........................1725 16.24. The PDF Table D ialog Box (N on-A diaba tic C ase With F lamelets) ......................................................1729 16.25. Mean S pecies M ole F raction D erived F rom an E quilibr ium C hemistr y Calcula tion ...........................1731 16.26. Mean Temp erature Derived F rom an E quilibr ium C hemistr y Calcula tion .........................................1732 16.27. 3D P lot of L ook-U p Table f or Temp erature Gener ated for a S imple H ydrocarbon S ystem..................1732 16.28. The Iner t Model D ialog Box............................................................................................................1735 xcviiRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide16.29. The Iner t Model D ialog Box............................................................................................................1736 16.30. The Velocity Inlet D ialog Box Showing M ixture Fraction B oundar y Conditions .................................1739 16.31. The S pecies M odel D ialog Box for a Two-M ixture-Fraction C alcula tion ............................................1744 16.32. Predic ted C ontours of M ixture Fraction in a M ethane D iffusion F lame ............................................1746 16.33. Predic ted C ontours of C O2 M ass F raction U sing the N on-P remix ed C ombustion M odel...................1746 17.1. The S pecies M odel D ialog Box for P remix ed C ombustion .................................................................1751 17.2. The S pecies M odel D ialog Box for the G-E qua tion M odel..................................................................1752 17.3. The S pecies M odel D ialog Box for ECFM ...........................................................................................1756 18.1. Premix ed F lamelet G ener ated M anifolds (F lamelet Tab)....................................................................1763 18.2. Diffusion F lamelet G ener ated M anifolds (F lamelet Tab)....................................................................1765 18.3. The S pecies M odel D ialog Box:Table Tab with no A utoma ted G rid Refinemen t.................................1766 18.4. The S pecies M odel D ialog Box:Table Tab D ispla ying A utoma ted G rid Refinemen t.............................1767 18.5. The S elec t Transp orted Sc alars D ialog Box.......................................................................................1768 18.6. The PDF Table D ialog Box (Adiaba tic C ase With FGM) .......................................................................1770 18.7. The PDF Table D ialog Box (N on-A diaba tic C ase With FGM) ................................................................1771 18.8. The S pecies M odel D ialog Box (Properties Tab).................................................................................1774 18.9. The Q uadr atic of M ixture Fraction D ialog Box...................................................................................1774 18.10. The P iecewise Linear D ialog Box....................................................................................................1775 18.11. The S pecies M odel D ialog Box(Premix Tab).....................................................................................1776 19.1. The S pecies M odel D ialog Box for Lagr angian C omp osition PDF Transp ort.......................................1781 19.2. The In tegration P aramet ers D ialog Box............................................................................................1782 19.3. The S pecies M odel D ialog Box for E uler ian C omp osition PDF Transp ort............................................1784 19.4. The Velocity Inlet D ialog Box for Euler ian C omp osition PDF Transp ort...............................................1786 19.5. The S olution Initializa tion Task P age f or Euler ian C omp osition PDF Transp ort....................................1787 19.6. The R un C alcula tion Task P age f or C omp osition PDF Transp ort.........................................................1788 19.7. The P article Tracks D ialog Box for Tracking PDF P articles ...................................................................1791 20.1. The In tegration P aramet ers D ialog Box............................................................................................1793 20.2. The Selec t DA C Target S pecies Dialog Box.....................................................................................1805 21.1. The S park Ignition D ialog Box..........................................................................................................1808 21.2. The S et Spark Ignition D ialog Box....................................................................................................1809 21.3. The S et Spark Ignition D ialog Box Displa ying the ECFM S park Model Options ...................................1810 21.4. The Ignition D elay Model in the A utoignition M odel D ialog Box.......................................................1812 21.5. The K nock M odel in the A utoignition M odel D ialog Box...................................................................1812 21.6. The Ignition D elay Model f or the P artially P remix ed C ombustion M odel...........................................1813 21.7. The K nock M odel with the P artially P remix ed C ombustion M odel Enabled ........................................1814 21.8. Exp erimen tal Engine M esh ..............................................................................................................1815 21.9. Cylinder M ass v s. Crank A ngle ..........................................................................................................1818 21.10. Cylinder P ressur e vs. Crank A ngle ...................................................................................................1819 21.11. Crevice Pressur es...........................................................................................................................1821 22.1. The NO x Model D ialog Box..............................................................................................................1825 22.2. The NO x Model D ialog Box Displa ying the F uel S treams ...................................................................1828 22.3. The NO x Dialog Box Displa ying the R ebur n Reduc tion M etho d.........................................................1834 22.4. The NO x Dialog Box Displa ying the SNCR R educ tion M etho d...........................................................1834 22.5. The NO x Model D ialog Box and the Turbulenc e Interaction M ode Tab...............................................1836 22.6. The SO x Model D ialog Box...............................................................................................................1842 22.7. The SO x Model D ialog Box Displa ying Liquid F uel P aramet ers..........................................................1845 22.8. The SO x Model D ialog Box Displa ying S olid F uel P aramet ers............................................................1846 22.9. The SO x Model D ialog Box for a G as Fuel Type with Turbulenc e........................................................1849 22.10. The M ass-F low Inlet D ialog Box: the Species Tab............................................................................1852 22.11. The S oot M odel D ialog Box for the One-S tep M odel.......................................................................1856 22.12. The S oot M odel D ialog Box for the Two-Step M odel.......................................................................1858 22.13. The S oot M odel D ialog Box for the M oss-B rookes M odel................................................................1860 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. xcviiiUser's G uide22.14. The S oot M odel D ialog Box for the M oss-B rookes M odel with a U ser-D efined P recursor C orrelation .1864 22.15. The P iecewise-P olynomial P rofile D ialog Box..................................................................................1866 22.16. The S oot M odel D ialog Box for the M etho d of M omen ts M odel......................................................1867 22.17. The S oot M odel D ialog Box for the D etailed CHEMKIN F ormat Soot M echanism ..............................1868 22.18. Sticking C oefficien ts for S oot P recursors ........................................................................................1869 22.19. Settings f or the N uclea tion M echanism ..........................................................................................1870 22.20. The D ecoupled D etailed C hemistr y Dialog Box...............................................................................1873 23.1. The A coustics M odel D ialog Box......................................................................................................1880 23.2. The A coustics M odel D ialog Box for a 3D S teady-State Case with a S ingle M oving R eference Frame ....1882 23.3. The A coustics M odel D ialog Box for Exp orting in C GNS F ormat.........................................................1884 23.4. The A coustics M odel D ialog Box......................................................................................................1885 23.5. The In terior C ell Z one S elec tion D ialog Box......................................................................................1886 23.6. An Interior S ource Sur face...............................................................................................................1886 23.7. The A coustic R eceivers D ialog Box...................................................................................................1888 23.8. The R un C alcula tion Task P age .........................................................................................................1890 23.9. The A coustic S ignals D ialog Box.......................................................................................................1892 23.10. The R ead ASD F iles Tab of the A coustic S ource FFT D ialog Box........................................................1896 23.11. The C omput e FFT F ields Tab of the A coustic S ource FFT D ialog Box................................................1897 23.12. The FFT Sur face Variables Tab of the A coustic S ource FFT D ialog Box for the O ctave Bands ..............1898 23.13. Bar C hart of Sur face Pressur e Level for O ctave Bands ......................................................................1899 23.14. The FFT Sur face Variables Tab of the A coustic S ource FFT D ialog Box for a S et of Individual M odes ...1900 23.15. The Write CGNS F iles Tab of the A coustic S ource FFT D ialog Box.....................................................1901 23.16. The A coustics M odel D ialog Box....................................................................................................1903 23.17. The B asic S hap es D ialog Box..........................................................................................................1905 23.18. The A coustics Wave Equa tion S olver C ontrols Task P age .................................................................1906 23.19. The A coustics Initializa tion D ialog Box...........................................................................................1907 23.20. The A coustics M odel D ialog Box for B roadband N oise ....................................................................1909 24.1. The D iscrete Phase M odel D ialog Box and the Tracking P aramet ers..................................................1923 24.2. The D iscrete Phase M odel D ialog Box and the P hysical M odels .........................................................1926 24.3. Discrete Phase D ialog Box with DEM C ollision M odel.......................................................................1930 24.4. Wall B oundar y Condition f or the DEM M odel...................................................................................1932 24.5. Collision D ialog Box.........................................................................................................................1933 24.6. DEM C ollision S ettings D ialog Box...................................................................................................1933 24.7. The D iscrete Phase M odel D ialog Box and the UDFs .........................................................................1936 24.8. The D iscrete Phase M odel D ialog Box and the N umer ics...................................................................1938 24.9. Particle Injec tion D efining a S ingle P article S tream ...........................................................................1946 24.10. Particle Injec tion D efining an Initial S patial D istribution of the P article S treams ..............................1946 24.11. Particle Injec tion D efining an Initial S pray Distribution of the P article Velocity.................................1946 24.12. Cone Injec tor G eometr y................................................................................................................1951 24.13. Flat Fan Viewed fr om A bove and fr om the S ide..............................................................................1959 24.14. Example of C umula tive Size Distribution of P articles ......................................................................1964 24.15. Rosin-R ammler C urve Fit for the Example P article S ize Data............................................................1965 24.16. The Injec tions B ranch in the Outline View....................................................................................1967 24.17. The Injec tions D ialog Box..............................................................................................................1967 24.18. The S et Injec tion P roperties D ialog Box..........................................................................................1969 24.19. Setting Sur face Injec tion P roperties ...............................................................................................1971 24.20. Mean Trajec tory in a Turbulen t Flow...............................................................................................1979 24.21. Stochastic Trajec tories in a Turbulen t Flow.....................................................................................1980 24.22. The C ustom La ws Dialog Box.........................................................................................................1981 24.23. The S et M ultiple Injec tion P roperties D ialog Box............................................................................1982 24.24. Discrete Phase B oundar y Conditions in the Wall D ialog Box............................................................1986 24.25. “Trap” Boundar y Condition f or the D iscrete Phase ...........................................................................1988 xcixRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide24.26. “Escape” Boundar y Condition f or the D iscrete Phase .......................................................................1988 24.27. The Wall D ialog Box: the P article-W all H eat Exchange Option ..........................................................1993 24.28. The S et Injec tion P roperties D ialog Box: Condensa te Injec tion ........................................................1995 24.29. The Gener ic Erosion M odel P aramet ers Dialog Box.....................................................................1997 24.30. The Finnie M odel P aramet ers Dialog Box.....................................................................................1997 24.31. The McLaury M odel P aramet ers Dialog Box.................................................................................1998 24.32. The Oka M odel P aramet ers Dialog Box........................................................................................1999 24.33. The Shear S tress M odel P aramet ers Dialog Box...........................................................................2000 24.34. The Erosion D ynamic M esh C oupling S etup Dialog Box..............................................................2002 24.35. The Run E rosion-D ynamic M esh S imula tion Dialog Box..............................................................2005 24.36. The Graphics O bjec ts Dialog Box..................................................................................................2007 24.37. The C omp onen ts Tab.....................................................................................................................2013 24.38. Uncoupled D iscrete Phase C alcula tions ..........................................................................................2023 24.39. Coupled D iscrete Phase C alcula tions ..............................................................................................2024 24.40. Effect of N umb er of S ource Term U pdates on S ource Term A pplied t o Flow Equa tions .....................2026 24.41. The P article Tracks D ialog Box........................................................................................................2029 24.42. The Track S tyle A ttribut es D ialog Box.............................................................................................2032 24.43. The P article S pher e Style A ttribut es D ialog Box..............................................................................2033 24.44. Particles with the Vector S tyle........................................................................................................2034 24.45. Particles with the C entered Vector S tyle.........................................................................................2035 24.46. Particles with the C entered C ylinder S tyle......................................................................................2036 24.47. The P article Vector S tyle A ttribut es D ialog Box...............................................................................2037 24.48. The Imp ort Particle D ata D ialog Box...............................................................................................2037 24.49. The P article F ilter A ttribut es D ialog Box..........................................................................................2038 24.50. The R eporting Variables D ialog Box................................................................................................2046 24.51. The S ample Trajec tories D ialog Box................................................................................................2055 24.52. The Trajec tory Sample Hist ograms D ialog Box................................................................................2057 24.53. The Trajec tory Sample Hist ograms D ialog Box: Correlation ..............................................................2059 24.54. The Trajec tory Sample Hist ograms D ialog Box: Data File R educ tion .................................................2060 24.55. The P article Summar y Dialog Box...................................................................................................2062 24.56. The S hared M emor y Option with Workpile A lgor ithm Enabled .......................................................2068 25.1. Macroscopic P article M odel D ialog Box (Particle Tracking Tab)..........................................................2073 25.2. Macroscopic P article M odel D ialog Box (D rag Tab)...........................................................................2075 25.3. Macroscopic P article M odel D ialog Box (Collision Tab)......................................................................2077 25.4. Macroscopic P article M odel D ialog Box (D eposition Tab)..................................................................2078 25.5. Macroscopic P article M odel D ialog Box (Injec tion Tab).....................................................................2079 25.6. Macroscopic P article M odel D ialog Box (Attraction F orces Tab).........................................................2088 25.7. Macroscopic P article M odel D ialog Box (Initializ e MPM Tab).............................................................2089 26.1. Multiphase M odel D ialog Box for the VOF M odel..............................................................................2094 26.2. Multiphase M odel D ialog Box for the M ixture Model........................................................................2095 26.3. Multiphase M odel D ialog Box for the E uler ian M odel.......................................................................2096 26.4. The P hases D ialog Box.....................................................................................................................2103 26.5. The S pecies M odel D ialog Box with a M ultiphase M odel Enabled .....................................................2105 26.6. The P hase P roperties D ialog Box......................................................................................................2106 26.7. The P hase In teraction D ialog Box for H eterogeneous R eactions ........................................................2107 26.8. The P hase In teraction D ialog Box for M ass Transf er...........................................................................2110 26.9. The C avitation M odel D ialog Box.....................................................................................................2115 26.10. Table Input f or Vaporization P ressur e.............................................................................................2116 26.11. The E vaporation-C ondensa tion M odel D ialog Box (Euler ian M ultiphase M odel) ..............................2119 26.12. The S pecies M ass Transf er M odel D ialog Box..................................................................................2122 26.13. The B oundar y Conditions Task P age ...............................................................................................2125 26.14. The P ressur e Inlet D ialog Box for a M ixture.....................................................................................2126 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. cUser's G uide26.15. The Wall D ialog Box for a M ixture in a M ultiphase C alcula tion with Wall A dhesion ...........................2127 26.16. Measur ing the C ontact Angle ........................................................................................................2128 26.17. The P orous J ump D ialog Box Displa ying J ump A dhesion ................................................................2129 26.18. The P ressur e Inlet D ialog Box for a P hase ........................................................................................2130 26.19. The P ressur e Outlet D ialog Box for a P hase .....................................................................................2130 26.20. The C ell Z one C onditions Task P age ...............................................................................................2131 26.21. Mass-F low Inlet B oundar y Condition D ialog Box............................................................................2137 26.22. Determining the F ree Sur face Level and the B ottom L evel..............................................................2148 26.23. Pressur e Inlet f or Op en C hannel F low.............................................................................................2150 26.24. Densit y Interpolation M etho d for Op en C hannel F low....................................................................2152 26.25. The Velocity Inlet f or Op en C hannel Wave BC .................................................................................2155 26.26. Segregated Velocity Inputs f or Op en C hannel Wave BC ...................................................................2156 26.27. The Velocity Inlet f or Op en C hannel Wave BC (Explicit F ormula tion) ................................................2158 26.28. The S olution Initializa tion Task P age ...............................................................................................2165 26.29. The F luid D ialog Box to Enable N umer ical Beach ............................................................................2168 26.30. Numer ical Beach S ketch................................................................................................................2170 26.31. The P rimar y Phase D ialog Box........................................................................................................2172 26.32. The S econdar y Phase D ialog Box for the VOF M odel.......................................................................2173 26.33. The P hase In teraction D ialog Box (Sur face Tension Tab)..................................................................2174 26.34. The P hase In teraction D ialog Box for the VOF M odel (D iscretiza tion Tab).........................................2178 26.35. The VOF-t o-DPM P aramet ers D ialog Box........................................................................................2186 26.36. The S econdar y Phase D ialog Box for the M ixture Model.................................................................2190 26.37. The S econdar y Phase D ialog Box for a G ranular P hase U sing the M ixture Model..............................2191 26.38. The S econdar y Phase D ialog Box Displa ying the In terfacial A rea C oncentration S ettings .................2194 26.39. The P hase In teraction D ialog Box for the M ixture Model (D rag Tab)................................................2197 26.40. The P hase In teraction D ialog Box for the M ixture Model ( SlipTab)..................................................2198 26.41. The E vaporation-C ondensa tion M odel D ialog Box..........................................................................2201 26.42. Boiling M odel Exp ert Options ........................................................................................................2205 26.43. Transition F unction v s.Volume F raction of Liquid ...........................................................................2207 26.44. The S econdar y Phase D ialog Box for a N on-G ranular P hase ............................................................2209 26.45. The S econdar y Phase D ialog Box for a G ranular P hase ....................................................................2211 26.46. Syamlal O brien M odel Dialog Box................................................................................................2218 26.47. Antal et al. Model D ialog Box.........................................................................................................2222 26.48. Tomiy ama M odel D ialog Box.........................................................................................................2222 26.49. Frank M odel D ialog Box.................................................................................................................2223 26.50. Hosok awa Model D ialog Box.........................................................................................................2224 26.51. Lopez de B ertodano M odel D ialog Box..........................................................................................2225 26.52. Simonin M odel D ialog Box............................................................................................................2226 26.53. Burns et al. Model D ialog Box.........................................................................................................2226 26.54. Diffusion—in—v of M odel D ialog Box............................................................................................2227 26.55. The Viscous M odel D ialog Box for an E uler ian M ultiphase C alcula tion .............................................2230 26.56. The P hase In teraction D ialog Box for Turbulenc e Interaction ...........................................................2231 26.57. Troshk o-Hassan M odel D ialog Box.................................................................................................2232 26.58. Sato M odel D ialog Box..................................................................................................................2232 26.59. Simonin-et-al M odel D ialog Box.....................................................................................................2233 26.60. The P hase In teraction D ialog Box for H eat Transf er.........................................................................2234 26.61. The P hase In teraction D ialog Box for In terfacial A rea......................................................................2235 26.62. The D ense D iscrete Phase M odel...................................................................................................2237 26.63. The D iscrete Phase D ialog Box.......................................................................................................2238 26.64. The S et Injec tion P roperties D ialog Box..........................................................................................2239 26.65. The D iscrete Phase D ialog Box for a G ranular P hase ........................................................................2240 26.66. The B oiling M odel.........................................................................................................................2242 ciRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide26.67. The S econdar y Phase D ialog Box...................................................................................................2244 26.68. The P hase In teraction D ialog Box...................................................................................................2244 26.69. The B oiling M odel D ialog Box........................................................................................................2246 26.70. The M ultiphase M odel D ialog Box with the Wet Steam M odel S elec ted...........................................2252 26.71. The S olution M etho ds Task P age D ispla ying The P ressur e-Velocity Coupling Options ......................2266 26.72. The S olution C ontrols Task P age D ispla ying the C oupled Volume F raction M etho d for the VOF and Mixture Models .......................................................................................................................................2268 26.73. The S olution C ontrols Task P age D ispla ying the C oupled Volume F raction M etho d for the E uler ian Multiphase M odel...................................................................................................................................2270 27.1. The P opula tion B alanc e Model D ialog Box.......................................................................................2287 27.2. The Sur face Tension f or P opula tion B alanc e Dialog Box....................................................................2290 27.3. The Hamak er C onstan t for P opula tion B alanc e Dialog Box................................................................2291 27.4. The Prince and Blanch M odel P aramet ers Dialog Box....................................................................2291 27.5. The Sur face Tension and Weber N umb er D ialog Box.........................................................................2292 27.6. The G hadir i Breakage C onstan t for P opula tion B alanc e Dialog Box...................................................2293 27.7. The S hap e Factor for P arabolic PDF D ialog Box.................................................................................2293 27.8. The G ener alized p df for multiple br eakage D ialog Box.....................................................................2294 27.9. The P opula tion B alanc e Model D ialog Box for the DQMOM M odel....................................................2296 27.10. DQMOM Values P roduced F rom a PDF F ile.....................................................................................2297 27.11. Specifying Inlet B oundar y Conditions f or the P opula tion B alanc e Model.........................................2300 27.12. The E qua tions D ialog Box..............................................................................................................2302 27.13. The S econdar y Phase D ialog box for H ydrodynamic C oupling ........................................................2303 27.14. The P hase In teraction D ialog Box for N on-r eacting S pecies .............................................................2305 27.15. The P hase In teraction D ialog Box for a H eterogeneous R eaction .....................................................2306 27.16. The P opula tion B alanc e Momen ts D ialog Box.................................................................................2308 27.17. The N umb er D ensit y Function D ialog Box......................................................................................2309 28.1. The S olidific ation and M elting D ialog Box........................................................................................2321 28.2. The C reate/Edit M aterials D ialog Box for M elting and S olidific ation ...................................................2323 28.3. The S olidific ation and M elting D ialog Box........................................................................................2325 28.4. Liquid F raction C ontours f or C ontinuous C rystal G rowth ..................................................................2327 29.1. The S tructural M odel D ialog Box......................................................................................................2331 29.2. The S tructure Tab of the Wall D ialog Box..........................................................................................2332 29.3. The Wall D ialog Box for a Two-Sided Wall..........................................................................................2333 30.1. Euler ian Wall F ilm S olution C ontrols (S teady Flow)............................................................................2342 30.2. Euler ian Wall F ilm S olution C ontrols (U nsteady Flow).......................................................................2343 30.3. Wall D ialog Box (Initial C onditions) ..................................................................................................2345 32.1. The B attery Model Option in the Outline View................................................................................2359 32.2. The B attery Model D ialog Box (M odel P aramet ers Tab).....................................................................2360 32.3. The B attery Model D ialog Box (Separ ator Tab)..................................................................................2362 32.4. The B attery Model D ialog Box (Electric Field Tab)..............................................................................2363 32.5. The MSMD B attery Model Option in the Outline View.....................................................................2370 32.6. The MSMD B attery Model D ialog Box (M odel Options Tab)...............................................................2372 32.7. Model P aramet ers Tab—NT GK M odel..............................................................................................2378 32.8. NTGK U-par amet er D ata Table D ialog Box........................................................................................2380 32.9. Model P aramet ers Tab—E quiv alen t Circuit M odel............................................................................2382 32.10. Model P aramet ers Tab—N ewman ’s P2D M odel..............................................................................2384 32.11. Model P aramet ers Tab—U ser-D efined E-M odel..............................................................................2387 32.12. The MSMD B attery Model D ialog Box (Conduc tive Zones Tab)........................................................2388 32.13. The MSMD B attery Model D ialog Box (Electric Contacts Tab)...........................................................2389 32.14. The MSMD B attery Model D ialog Box (Advanced Option Tab).........................................................2391 33.1. The PEMFC Option in the Outline View...........................................................................................2412 33.2. The M odel Options in the PEM F uel C ell M odel D ialog Box...............................................................2414 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. ciiUser's G uide33.3. The P aramet ers Tab of the PEM F uel C ell M odel D ialog Box...............................................................2417 33.4. The A node Tab of the PEM F uel C ell M odel D ialog Box with C urrent Collec tor S elec ted.....................2420 33.5. The A node Tab of the PEM F uel C ell M odel D ialog Box with F low Channel S elec ted...........................2421 33.6. The A node Tab of the PEM F uel C ell M odel D ialog Box with P orous E lectrode S elec ted......................2422 33.7. The A node Tab of the PEM F uel C ell M odel D ialog Box with TPB La yer (C atalyst) S elec ted..................2423 33.8. The A node Tab of the PEM F uel C ell M odel D ialog Box with M icro Porous La yer Selec ted..................2425 33.9. The E lectrolyte Tab of the PEM F uel C ell M odel D ialog Box................................................................2427 33.10. The C athode Tab of the PEM F uel C ell M odel D ialog Box with TPB La yer (C atalyst) S elec ted.............2429 33.11. The A dvanced Tab of the PEM F uel C ell M odel D ialog Box for C ontact Resistivities ..........................2431 33.12. The A dvanced Tab of the PEM F uel C ell M odel D ialog Box for the C oolan t Channel ..........................2433 33.13. The A dvanced Tab of the PEM F uel C ell M odel D ialog Box for S tack M anagemen t...........................2434 33.14. The R eports Tab of the PEM F uel C ell M odel D ialog Box..................................................................2435 33.15. The F uel C ell and E lectrolysis Option in the Tree.............................................................................2447 33.16. The M odel Options in the F uel C ell and E lectrolysis M odels D ialog Box—PEMFC Enabled ................2448 33.17. The P aramet ers Tab of the F uel C ell and E lectrolysis M odels D ialog Box...........................................2450 33.18. The A node Tab of the F uel C ell and E lectrolysis M odels D ialog Box With C urrent Collec tor Selec ted..2452 33.19. The A node Tab of the F uel C ell and E lectrolysis M odels D ialog Box With F low Channel S elec ted......2453 33.20. The A node Tab of the F uel C ell and E lectrolysis M odels D ialog Box With P orous E lectrode S elec ted..2453 33.21. The A node Tab of the F uel C ell and E lectrolysis M odels D ialog Box With TPB La yer (C atalyst) S elec- ted.........................................................................................................................................................2454 33.22. The E lectrolyte Tab of the F uel C ell and E lectrolysis M odels D ialog Box...........................................2455 33.23. The C athode Tab of the F uel C ell and E lectrolysis M odels D ialog Box With C urrent Collec tor Selec- ted.........................................................................................................................................................2456 33.24. The C athode Tab of the F uel C ell and E lectrolysis M odels D ialog Box With F low Channel S elec ted....2457 33.25. The C athode Tab of the F uel C ell and E lectrolysis M odels D ialog Box With P orous E lectrode S elec- ted.........................................................................................................................................................2458 33.26. The C athode Tab of the F uel C ell and E lectrolysis M odels D ialog Box With TPB La yer (C atalyst) S elec- ted.........................................................................................................................................................2459 33.27. The A dvanced Tab of the F uel C ell and E lectrolysis M odels D ialog Box for C ontact Resistivities ........2460 33.28. The A dvanced Tab of the F uel C ell and E lectrolysis M odels D ialog Box for the C oolan t Channel .......2461 33.29. The A dvanced Tab of the F uel C ell and E lectrolysis M odels D ialog Box for Stack M anagemen t.........2462 33.30. The R eports Tab of the F uel C ell and E lectrolysis M odels D ialog Box................................................2464 33.31. The E lectric Conduc tivit y Field in the C reate/Edit M aterials D ialog Box............................................2465 33.32. Opening the SOFC M odel D ialog Box in the Outline View..............................................................2474 33.33. The M odel P aramet ers Tab in the SOFC M odel D ialog Box...............................................................2483 33.34. The E lectrochemistr y Tab in the SOFC M odel D ialog Box................................................................2485 33.35. The E lectrolyte and Tortuosit y Tab in the SOFC M odel D ialog Box...................................................2487 33.36. The E lectric Field Tab in the SOFC M odel D ialog Box.......................................................................2488 34.1. Enabling the MHD M odel D ialog Box...............................................................................................2497 34.2. The MHD M odel D ialog Box.............................................................................................................2498 34.3. The MHD M odel D ialog Box for P atching an Ex ternal M agnetic F ield .................................................2499 34.4. The MHD M odel D ialog Box for S pecifying a M oving F ield ................................................................2500 34.5. The MHD M odel D ialog Box for Imp orting an Ex ternal M agnetic F ield ...............................................2501 34.6. Apply Ex ternal B0 F ield D ialog Box...................................................................................................2502 34.7. Cell B oundar y Condition S etup ........................................................................................................2503 34.8. Editing M aterial P roperties within B oundar y Condition S etup ..........................................................2504 34.9. Wall B oundar y Condition S etup .......................................................................................................2505 34.10. Conduc ting Wall B oundar y Conditions in E lectrical Potential M etho d.............................................2506 34.11. Solution C ontrol Tab in the MHD M odel D ialog Box........................................................................2507 35.1. The F iber M odel D ialog Box.............................................................................................................2520 35.2. The F iber Injec tions D ialog Box........................................................................................................2526 35.3. The S et Fiber Injec tion P roperties D ialog Box...................................................................................2530 ciiiRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide35.4. The S et Fiber Injec tion P roperties D ialog Box With Take-Up Point Properties .....................................2532 35.5. Line Injec tions .................................................................................................................................2533 35.6. Matrix Injec tions .............................................................................................................................2534 35.7. Equidistan t Fiber G rid......................................................................................................................2534 35.8. One-S ided F iber G rid.......................................................................................................................2535 35.9. Two-Sided F iber G rid.......................................................................................................................2535 35.10. Three-S ided F iber G rid...................................................................................................................2536 35.11. Defining a Three-S ided F iber G rid U sing the S et Fiber Injec tion P roperties D ialog Box.....................2536 35.12. The F iber M odel D ialog Box...........................................................................................................2542 35.13. Fiber Solution C ontrols D ialog Box.................................................................................................2543 35.14. Displa ying F iber Locations U sing the C ontours D ialog Box..............................................................2545 35.15. The F iber M esh D ispla y Dialog Box.................................................................................................2546 35.16. The F iber Style A ttribut es D ialog Box.............................................................................................2546 35.17. The F iber D ispla y Dialog Box..........................................................................................................2549 36.1. The R educ ed Or der M odel D ialog Box..............................................................................................2552 37.1. The G ener al Task P age .....................................................................................................................2561 37.2. The S olution M etho ds Task P age f or the HO TR Option ......................................................................2566 37.3. The R elaxa tion Options D ialog Box..................................................................................................2567 37.4. The S olution M etho ds Task P age f or the P ressur e-Based S egregated A lgor ithm ................................2568 37.5. The S olution C ontrols Task P age f or the P ressur e-Based S olver..........................................................2574 37.6. The A dvanced S olution C ontrols D ialog Box for the P ressur e-Based S egregated N on-I terative Solver.2577 37.7. The S olution C ontrols Task P age f or the D ensit y-Based Explicit F ormula tion ......................................2583 37.8. The S olution M etho ds Task P age f or the D ensit y-Based Implicit F ormula tion .....................................2585 37.9. The M ultigr id Tab............................................................................................................................2590 37.10. The A dvanced S olution C ontrols D ialog Box...................................................................................2598 37.11. The S olution Limits D ialog Box.......................................................................................................2599 37.12. The M ulti-S tage Tab.......................................................................................................................2602 37.13. The S olution Initializa tion Task P age ...............................................................................................2606 37.14. The P atch D ialog Box.....................................................................................................................2608 37.15. The S olution Initializa tion Task P age f or H ybrid Initializa tion ...........................................................2612 37.16. The H ybrid Initializa tion D ialog Box...............................................................................................2613 37.17. The R un C alcula tion Task P age .......................................................................................................2615 37.18. The S olution M etho ds Task P age ....................................................................................................2619 37.19. The S olution C ontrols Task P age f or the P seudo Transien t Runs .......................................................2620 37.20. The A dvanced S olution C ontrols D ialog Box for the P seudo Transien t Metho d................................2622 37.21. The R un C alcula tion Task P age f or the U ser-S pecified P seudo Transien t Time S tep M etho d..............2623 37.22. The R un C alcula tion Task P age f or the A utoma tic P seudo Transien t Option .....................................2625 37.23. Time-D ependen t Calcula tion of Vortex Shedding (t=36.6 sec) .........................................................2626 37.24. Time-D ependen t Calcula tion of Vortex Shedding (t=41.6 sec) .........................................................2627 37.25. The G ener al Task P age f or a Transien t Calcula tion ...........................................................................2628 37.26. The S olution M etho ds Task P age f or a Transien t Calcula tion ............................................................2629 37.27. The R un C alcula tion Task P age f or Implicit Transien t Calcula tions ....................................................2633 37.28. The S ampling Options D ialog Box..................................................................................................2638 37.29. Lift Coefficien t Plot f or a Time-P eriodic S olution .............................................................................2646 37.30. The R esidual M onit ors D ialog Box..................................................................................................2650 37.31. The R esidual M onit ors D ialog Box Displa ying R elative or A bsolut e Convergenc e.............................2652 37.32. Report File for 'flo w-time', 'delta-time', and 'it ers-p er-timest ep'.......................................................2656 37.33. Fluctuating S imula tion Example ....................................................................................................2659 37.34. The Ex ecut e Commands D ialog Box...............................................................................................2661 37.35. The D efine M acro Dialog Box.........................................................................................................2663 37.36. The A utoma tically Initializ e Solution and M odify C ase Option .........................................................2665 37.37. The A utoma tic S olution Initializa tion and C ase M odific ation D ialog Box..........................................2666 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. civUser's G uide37.38. The C ase M odific ation Tab.............................................................................................................2667 37.39. The R un C alcula tion Task P age .......................................................................................................2669 37.40. The E dit A utoma tic Initializa tion and C ase M odific ations D ialog Box...............................................2670 37.41. The A nima tion D efinition D ialog Box.............................................................................................2671 37.42. The P layback D ialog Box................................................................................................................2673 37.43. The C ase C heck D ialog Box............................................................................................................2678 37.44. The Inf ormation D ialog Box...........................................................................................................2678 37.45. The M esh Tab in the C ase C heck D ialog Box...................................................................................2680 37.46. The M odels Tab in the C ase C heck D ialog Box................................................................................2682 37.47. The B oundar ies and C ell Z ones Tab in the C ase C heck D ialog Box...................................................2684 37.48. The M aterials Tab in the C ase C heck D ialog Box..............................................................................2687 37.49. The S olver Tab in the C ase C heck D ialog Box..................................................................................2688 37.50. Reporting P oor Q ualit y Elemen ts...................................................................................................2695 37.51. The R un C alcula tion Task P age with S olution S teering Enabled .......................................................2700 37.52. The S olution S teering D ialog Box...................................................................................................2702 37.53. The FMG S ettings Tab in the S olution S teering D ialog Box..............................................................2703 38.1. Turbine C ascade M esh B efore Adaption ...........................................................................................2706 38.2. Turbine C ascade M esh af ter A daption ..............................................................................................2706 38.3. The A daption C ontrols D ialog Box...................................................................................................2709 38.4. Additional R efinemen t Layers: 1, 2, 3................................................................................................2710 38.5. Marking B oundar y Cells...................................................................................................................2711 38.6. Mesh B efore Adaption .....................................................................................................................2712 38.7. Mesh af ter B oundar y Adaption ........................................................................................................2713 38.8. Wing M esh B efore Adaption ............................................................................................................2714 38.9. Marking C ells B ased on R egion ........................................................................................................2715 38.10. Wing M esh A fter R egion C ell R egist er-B ased A daption ...................................................................2716 38.11. Field Variable R efinemen t Regist er.................................................................................................2717 38.12. Field Variable C oarsening R egist er.................................................................................................2717 38.13. Controls f or R efining and C oarsening the M esh ..............................................................................2718 38.14. Simple Expr ession R efinemen t Setting ...........................................................................................2719 38.15. Cells M arked for S imple Expr ession R efinemen t.............................................................................2720 38.16. Advanced Expr ession R efinemen t Setting ......................................................................................2720 38.17. Cells M arked for A dvanced Expr ession R efinemen t.........................................................................2721 38.18. The A nisotr opic A daption D ialog Box.............................................................................................2722 38.19. The G eometr y Based A daption D ialog Box.....................................................................................2724 38.20. The G eometr y Based A daption C ontrols D ialog Box.......................................................................2725 39.1. The Z one Sur face Dialog Box...........................................................................................................2729 39.2. Contours of C ell P artitions on P artition Sur face Overlaid on M esh .....................................................2730 39.3. The P artition Sur face Dialog Box......................................................................................................2731 39.4. The Impr int Sur face Dialog Box........................................................................................................2732 39.5. Impr inted Sur face (pink) Sup erimp osed O ver Imp orted Sur face (whit e)............................................2734 39.6. The P oint Sur face Dialog Box...........................................................................................................2735 39.7. The P oint Tool.................................................................................................................................2736 39.8. The S tructural Point Sur face Dialog Box...........................................................................................2737 39.9. The Line/R ake Sur face Dialog Box....................................................................................................2739 39.10. The Line Tool.................................................................................................................................2741 39.11. The P lane Sur face Dialog Box.........................................................................................................2743 39.12. The P lane Tool...............................................................................................................................2745 39.13. The Q uadr ic Sur face Dialog Box.....................................................................................................2747 39.14. The Iso-Sur face Dialog Box............................................................................................................2749 39.15. External Wall Sur face Isoclipp ed t o Values of x C oordina te..............................................................2751 39.16. The Iso-C lip D ialog Box..................................................................................................................2752 cvRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide39.17. The Transf orm Sur face Dialog Box..................................................................................................2754 39.18. The Sur faces D ialog Box................................................................................................................2756 39.19. Region R egist er D ialog Box............................................................................................................2760 39.20. Boundar y Regist er D ialog Box........................................................................................................2762 39.21. Limit R egist er D ialog Box...............................................................................................................2763 39.22. Field Variable R egist er D ialog Box..................................................................................................2765 39.23. Residual R egist er D ialog Box..........................................................................................................2767 39.24. Volume C hange—R atio of the Volumes of the C ells ........................................................................2768 39.25. Volume R egist er D ialog Box...........................................................................................................2768 39.26. Airfoil Wall C ells M arked b y Y+ Values .............................................................................................2769 39.27. Yplus/Ystar R egist er D ialog Box.....................................................................................................2770 39.28. Manage C ell R egist ers D ialog Box..................................................................................................2771 39.29. Report Regist er D ialog Box............................................................................................................2772 39.30. Manage R egist er Op erations D ialog Box........................................................................................2773 40.1. Outline D ispla y...............................................................................................................................2776 40.2. Mesh E dge D ispla y..........................................................................................................................2777 40.3. Mesh F ace (Filled M esh) D ispla y.......................................................................................................2777 40.4. Node D ispla y..................................................................................................................................2778 40.5. The M esh D ispla y Dialog Box...........................................................................................................2779 40.6. The M esh C olors D ialog Box.............................................................................................................2780 40.7. Standar d Outline of C omple x Duct..................................................................................................2781 40.8. Feature Outline of C omple x Duct.....................................................................................................2782 40.9. Mesh D ispla y with S hrink F actor = 0 .................................................................................................2783 40.10. Mesh D ispla y with S hrink F actor = 0.01 ..........................................................................................2783 40.11. Contours of S tatic P ressur e............................................................................................................2784 40.12. Profile P lot of y Velocity.................................................................................................................2785 40.13. The C ontours D ialog Box...............................................................................................................2786 40.14. The P rofile Options D ialog Box.......................................................................................................2787 40.15. Filled C ontours of S tatic P ressur e...................................................................................................2788 40.16. Filled C ontours with C lip to Range On ............................................................................................2790 40.17. Filled C ontours with C lip to Range O ff............................................................................................2790 40.18. Velocity Vector P lot........................................................................................................................2794 40.19. The Vectors D ialog Box..................................................................................................................2795 40.20. The Vector Options D ialog Box.......................................................................................................2796 40.21. Velocity Vectors G ener ated U sing the In P lane Option ....................................................................2797 40.22. The C ustom Vectors D ialog Box......................................................................................................2800 40.23. The Vector D efinitions D ialog Box..................................................................................................2801 40.24. Pathline P lot..................................................................................................................................2803 40.25. The P athlines D ialog Box...............................................................................................................2804 40.26. The Sc ene D ialog Box....................................................................................................................2812 40.27. The S weep Sur face Dialog Box.......................................................................................................2814 40.28. The C reate Sur face Dialog Box.......................................................................................................2815 40.29. Explo ded Sc ene D ispla y of Temp erature and Velocity.....................................................................2818 40.30. The D ispla y Options D ialog Box.....................................................................................................2819 40.31. Graphics Windo w with Text Annota tion .........................................................................................2822 40.32. The A nnota te Dialog Box...............................................................................................................2822 40.33. The C olor map D ialog Box..............................................................................................................2824 40.34. The D efault C olor map Lab el D ispla y..............................................................................................2826 40.35. The C olor map with S kipped Lab els................................................................................................2827 40.36. The C olor map E ditor D ialog Box....................................................................................................2828 40.37. The Ligh ts D ialog Box....................................................................................................................2830 40.38. Using the Triad t o Change the Or ientation of the O bjec t.................................................................2837 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. cviUser's G uide40.39. The Views Dialog Box.....................................................................................................................2838 40.40. The C amer a Paramet ers D ialog Box................................................................................................2838 40.41. Zooming In (M agnifying the D ispla y).............................................................................................2841 40.42. Zooming Out (S hrinking the D ispla y).............................................................................................2841 40.43. Camer a Definition .........................................................................................................................2842 40.44. The Write Views Dialog Box............................................................................................................2844 40.45. Mirroring A cross a S ymmetr y Boundar y.........................................................................................2845 40.46. The Views Dialog Box.....................................................................................................................2845 40.47. Before Applying P eriodicit y...........................................................................................................2846 40.48. After A pplying P eriodicit y..............................................................................................................2846 40.49. The G raphics P eriodicit y Dialog Box...............................................................................................2847 40.50. The M irror P lanes D ialog Box.........................................................................................................2848 40.51. The Sc ene D escr iption D ialog Box..................................................................................................2849 40.52. The D ispla y Properties D ialog Box..................................................................................................2850 40.53. Velocity Vectors Transla ted Outside the D omain f or B etter Viewing .................................................2852 40.54. The Transf ormations D ialog Box.....................................................................................................2853 40.55. The Iso-V alue D ialog Box................................................................................................................2854 40.56. The P athline A ttribut es D ialog Box.................................................................................................2855 40.57. Graphics D ispla y with B ounding F rame ..........................................................................................2856 40.58. The B ounding F rame D ialog Box....................................................................................................2856 40.59. The A nima te Dialog Box................................................................................................................2858 40.60. Sample X Y Plot..............................................................................................................................2863 40.61. Sample Hist ogram.........................................................................................................................2864 40.62. The S olution X Y Plot D ialog Box.....................................................................................................2865 40.63. Geometr y Used f or X Y Plot............................................................................................................2867 40.64. Data Plotted a t Outlet U sing a P lot D irection of (1,0,0) ....................................................................2867 40.65. Data Plotted a t Outlet U sing a P lot D irection of (0,1,0) ....................................................................2868 40.66. The F ile X Y Plot D ialog Box............................................................................................................2870 40.67. The P lot P rofile D ata D ialog Box.....................................................................................................2871 40.68. The P lot In terpolated D ata D ialog Box............................................................................................2872 40.69. Iso-C lips C reated F or C ircumf erential A veraging .............................................................................2873 40.70. XY Plot of C ircumf erential A verages ...............................................................................................2874 40.71. The Hist ogram D ialog Box.............................................................................................................2876 40.72. The A xes D ialog Box......................................................................................................................2877 40.73. The C urves D ialog Box...................................................................................................................2879 40.74. The Turbo Topology Dialog Box......................................................................................................2882 40.75. Turbomachiner y Boundar y Types...................................................................................................2884 40.76. The Turbo Report Dialog Box.........................................................................................................2885 40.77. Pump or C ompr essor .....................................................................................................................2889 40.78. Turbine .........................................................................................................................................2891 40.79. The Turbo Averaged C ontours D ialog Box......................................................................................2893 40.80. Turbo Averaged F illed C ontours of S tatic P ressur e..........................................................................2894 40.81. The Turbo 2D C ontours D ialog Box.................................................................................................2895 40.82. The Turbo Averaged X Y Plot D ialog Box..........................................................................................2896 40.83. The Turbo Options D ialog Box........................................................................................................2897 40.84. The F ourier Transf orm D ialog Box...................................................................................................2901 40.85. The P lot/M odify Input S ignal D ialog Box........................................................................................2902 40.86. A-, B-, and C-W eigh ting F unctions ..................................................................................................2906 41.1. Report Definitions D ialog Box..........................................................................................................2913 41.2. Sur face Report Definition D ialog Box...............................................................................................2915 41.3. Volume R eport Definition D ialog Box...............................................................................................2916 41.4. Force Report Definition D ialog Box..................................................................................................2918 cviiRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide41.5. Drag R eport Definition D ialog Box...................................................................................................2919 41.6. Lift Report Definition D ialog Box.....................................................................................................2920 41.7. Momen t Report Definition D ialog Box.............................................................................................2921 41.8. Flux R eport Definition D ialog Box....................................................................................................2923 41.9. DPM S ource Report Definition D ialog Box........................................................................................2924 41.10. DPM R eport Definition D ialog Box.................................................................................................2925 41.11. User D efined R eport Definition D ialog Box.....................................................................................2927 41.12. Expr ession R eport Definition D ialog Box........................................................................................2928 41.13. New R eport File D ialog Box...........................................................................................................2930 41.14. Report File D efinitions D ialog Box..................................................................................................2931 41.15. Edit R eport File D ialog Box.............................................................................................................2932 41.16. New R eport Plot D ialog Box...........................................................................................................2933 41.17. Report Plot D efinitions D ialog Box.................................................................................................2934 41.18. Edit R eport Plot D ialog Box............................................................................................................2935 41.19. The F lux R eports D ialog Box..........................................................................................................2937 41.20. The S ave Output P aramet er D ialog Box..........................................................................................2938 41.21. The F lux R eports D ialog Box..........................................................................................................2940 41.22. The F lux R eports D ialog Box with DPM ...........................................................................................2941 41.23. The F orce Reports D ialog Box........................................................................................................2943 41.24. An Airfoil with its C omput ed C enter of P ressur e.............................................................................2945 41.25. The F orce Reports D ialog Box for a C enter of P ressur e Report.........................................................2945 41.26. The P rojec ted Sur face Areas D ialog Box.........................................................................................2946 41.27. The Sur face Integrals D ialog Box....................................................................................................2948 41.28. The Volume In tegrals D ialog Box....................................................................................................2950 41.29. The R eference Values Task P age .....................................................................................................2953 41.30. The Input Summar y Dialog Box......................................................................................................2954 42.1. Computing N ode Values ..................................................................................................................2960 42.2. Cylindr ical Velocity Comp onen ts in 3D , 2D, and A xisymmetr ic Domains ............................................2962 42.3. The C ustom F ield F unction C alcula tor D ialog Box.............................................................................3040 42.4. The F ield F unction D efinitions D ialog Box........................................................................................3042 43.1. ANSY S Fluen t Architecture..............................................................................................................3046 43.2. The P arallel S ettings Tab of F luen t Launcher .....................................................................................3049 43.3. The Scheduler Tab of F luen t Launcher ( Windo ws 64 Version) ............................................................3052 43.4. The R emot e Tab of F luen t Launcher .................................................................................................3055 43.5. Partitioning the M esh ......................................................................................................................3069 43.6. The A uto Partition M esh D ialog Box.................................................................................................3070 43.7. The P artitioning and L oad B alancing D ialog Box..............................................................................3072 43.8. The Weigh ting Tab in the P artitioning and L oad B alancing D ialog Box..............................................3075 43.9. The P artitioned M esh ......................................................................................................................3077 43.10. The P artitioned ID S et to Zero........................................................................................................3079 43.11. The P artitioned ID S et to 1.............................................................................................................3079 43.12. The D ynamic L oad B alancing Tab...................................................................................................3082 43.13. Partitions C reated with the C artesian A xes M etho d........................................................................3085 43.14. Partitions C reated with the C artesian S trip or C artesian X-C oordina te Metho d................................3086 43.15. Partitions C reated with the P rincipal A xes M etho d.........................................................................3086 43.16. Partitions C reated with the P rincipal S trip or P rincipal X-C oordina te Metho d..................................3087 43.17. Partitions C reated with the P olar A xes or P olar Theta-C oordina te Metho d.......................................3087 43.18. The S mooth Optimiza tion Scheme .................................................................................................3088 43.19. The M erge Optimiza tion Scheme ...................................................................................................3088 43.20. The Thread C ontrol D ialog Box.......................................................................................................3095 43.21. The P arallel C onnec tivit y Dialog Box..............................................................................................3096 44.1. Adjoin t Obser vables D ialog Box.......................................................................................................3124 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. cviiiUser's G uide44.2. Create New O bser vable D ialog Box (O bser vable Types)....................................................................3125 44.3. Create New O bser vable D ialog Box (Op eration Types)......................................................................3126 44.4. Manage A djoin t Obser vables D ialog Box.........................................................................................3127 44.5. Adjoin t Obser vables D ialog Box.......................................................................................................3130 44.6. Adjoin t Solution M etho ds D ialog Box..............................................................................................3131 44.7. The S tabiliz ed Scheme & S trategy Settings D ialog Box......................................................................3135 44.8. The D issipa tion Scheme S ettings .....................................................................................................3136 44.9. The R esidual M inimiza tion Scheme S ettings ....................................................................................3137 44.10. Adjoin t Residual M onit ors D ialog Box............................................................................................3142 44.11. Run A djoin t Calcula tion D ialog Box................................................................................................3143 44.12. Adjoin t Reporting D ialog Box........................................................................................................3148 44.13. Design Tool D ialog Box..................................................................................................................3149 44.14. A C ylindr ical Region ......................................................................................................................3152 44.15. The D esign C ondition D ispla y Options D ialog Box..........................................................................3156 44.16. Specifying a B ounding P lane f or D esign C hanges ...........................................................................3157 44.17. The B ounding Or ientation D ialog Box............................................................................................3158 44.18. The S trict Conditions D ialog Box....................................................................................................3165 44.19. The D esign Exp ort Dialog Box........................................................................................................3167 44.20. The P review M orphing D ialog Box.................................................................................................3167 44.21. The Exp ort STL D ialog Box.............................................................................................................3168 44.22. Gradien t-Based Optimiz er D ialog Box............................................................................................3170 44.23. Adjoin t Optimiz er O bser vables D ialog Box.....................................................................................3171 44.24. Adjoin t Optimiz er C onditions D ialog Box.......................................................................................3171 44.25. Adjoin t Optimiza tion Hist ory Monit or D ialog Box...........................................................................3174 44.26. Adjoin t Optimiz er A utosave Dialog Box.........................................................................................3175 44.27. The R egions Tab of the M esh M orpher/Optimiz er D ialog Box..........................................................3183 44.28. The R egions Tab of the M esh M orpher/Optimiz er D ialog Box for an U nstr uctured D istribution ........3185 44.29. Displa ying the C ontrol Points for a R egular D istribution .................................................................3187 44.30. The D efine C ontrol Points D ialog Box.............................................................................................3188 44.31. Displa ying the C ontrol Points for an U nstr uctured D istribution .......................................................3190 44.32. The C onstr aints Tab of the M esh M orpher/Optimiz er D ialog Box.....................................................3192 44.33. The D eformation Tab of the M esh M orpher/Optimiz er D ialog Box..................................................3193 44.34. The P aramet er B ounds D ialog Box.................................................................................................3194 44.35. The M otion S ettings D ialog Box for a R egular D istribution ..............................................................3195 44.36. The M otion S ettings D ialog Box for an U nstr uctured D istribution ...................................................3198 44.37. The Optimiz er Tab of the M esh M orpher/Optimiz er D ialog Box.......................................................3201 44.38. The O bjec tive Function D efinition D ialog Box................................................................................3202 44.39. The Optimiza tion Hist ory Monit or D ialog Box.................................................................................3205 45.1. Force transf erred t o System C oupling when P orous J ump Thick ness is N on-Z ero..............................3213 45.2. Skewed pr ism c ells due t o transla tional motion b etween t wo bodies in close pr oximit y ...................3220 45.3. Example geometr y..........................................................................................................................3220 45.4. Cell Z one c ontaining the inner b oundar y layer mesh ........................................................................3221 45.5. Cell Z one c ontaining the out er b oundar y layer mesh .......................................................................3222 45.6. Cell Z one c ontaining the in terior mesh ............................................................................................3222 45.7. Prism la yer mesh qualit y main tained f or lar ge def ormations .............................................................3223 45.8. Overset mesh gener ated using 3 separ ate meshes ...........................................................................3224 45.9. Prism la yer mesh qualit y is main tained ............................................................................................3224 45.10. Original M esh (lef t) and def ormed mesh (r ight) with smo othing and r emeshing enabled ...............3226 45.11. Original M esh (lef t) and def ormed mesh (r ight) using smo othing and R egion F ace Remeshing .......3227 47.1. The B asic S hap es D ialog Box............................................................................................................3377 47.2. Orientation C alcula tor D ialog Box....................................................................................................3595 47.3. The A coustics Initializa tion D ialog Box.............................................................................................3622 cixRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uide1. Quadr ilateral M esh ..............................................................................................................................3978 2. Quadr ilateral M esh with P eriodic B oundar ies........................................................................................3979 3. Quadr ilateral M esh with Hanging N odes ..............................................................................................3980 1.1. Progress B ar with S tart Server Option ................................................................................................4018 1.2. Progress B ar with S tart Client Option .................................................................................................4019 1.3. Actions R ibbon Tab...........................................................................................................................4022 1.4. Run C alcula tion P roperties ................................................................................................................4022 1.5. Example S olution M etho ds................................................................................................................4023 1.6. Example S olution C ontrols................................................................................................................4023 1.7. Example R esiduals P roperties ............................................................................................................4024 1.8. Example G raphics O bjec t Properties ..................................................................................................4025 1.9. Viewing R ibbon Tab..........................................................................................................................4026 1.10. Example of S ending a C ommand: Changing the Velocity Units t o cm/s .............................................4027 1.11. Writing C ase and/or D ata fr om the C lient.........................................................................................4028 2.1.The F luen t Icing G raphic al U ser In terface...........................................................................................4040 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. cxUser's G uideList of Tables 1.1. Supp orted Versions of Third-Party Software...........................................................................................21 4.1. Available C ommand Line Options f or Linux and Windo ws Platforms.......................................................47 22.1. Default S tyle A ttribut es.....................................................................................................................480 23.1. Skewness R anges and C ell Q ualit y.....................................................................................................495 5. Mini F low Chart Symb ol D escr iptions ....................................................................................................dxlv 3.1. CGNS Variables Supp orted b y ANSY S Fluen t........................................................................................605 3.2. FEA F ile Ex tensions f or FSI M apping .....................................................................................................640 3.3. Units A ssociated with the Temp erature Units D rop-D own List S elec tions ..............................................645 5.1. Operations and F unctions ...................................................................................................................660 5.2. Solution Variables ...............................................................................................................................662 5.3. Scien tific C onstan ts.............................................................................................................................663 5.4. Aliases ................................................................................................................................................663 5.5. Field Variables .....................................................................................................................................679 7.1. Zone Types b y Categor y......................................................................................................................836 7.2. Air-side R adia tor D ata.......................................................................................................................1014 7.3. Reduc ed R adia tor D ata......................................................................................................................1014 7.4. CSV P rofile S ection Iden tifiers .......................................................................................................1054 7.5. Profile Types and the C orresponding R equir ed F ield Lab els................................................................1055 8.1. Recommended S ettings f or Op erating P ressur e.................................................................................1153 8.2.Temp erature Limits f or D roplet M aterials in ANSY S Fluen t Database pr odb.scm ..................................1171 8.3. Fluids Supp orted b y REFPR OP v9.1 ....................................................................................................1175 14.1. NTU M odel Vs. Simple E ffectiveness M odel.......................................................................................1575 15.1. Modified S pecific H eat Capacit y (Cp) P olynomial C oefficien ts ..........................................................1646 23.1. Source Data Saved in S ource Data Files ............................................................................................1882 24.1. Property Inputs f or Iner t Particles ....................................................................................................2008 24.2. Property Inputs f or D roplet P articles ................................................................................................2008 24.3. Property Inputs f or C ombusting P articles (La ws 1–4) ........................................................................2009 24.4. Property Inputs f or C ombusting P articles (La w 5) .............................................................................2010 24.5. Property Inputs f or M ultic omp onen t Particles (La w 7) ......................................................................2011 24.6. Common M ean D iamet ers and Their F ields of A pplic ation ................................................................2061 26.1. Spatial D iscretiza tion Schemes f or the VOF and E uler ian with M ulti-F luid VOF M odels .......................2099 26.2. Spatial D iscretiza tion Schemes f or the E uler ian M odel without M ulti-F luid VOF.................................2099 26.3. Spatial D iscretiza tion Schemes f or the M ixture Model......................................................................2099 26.4. Phase-S pecific and M ixture Conditions f or the VOF M odel................................................................2133 26.5. Phase-S pecific and M ixture Conditions f or the M ixture Model..........................................................2134 26.6. Phase-S pecific and M ixture Conditions f or the E uler ian M odel (f or Laminar F low).............................2138 26.7. Phase-S pecific and M ixture Conditions f or the E uler ian M odel (with the M ixture Turbulenc e Model) ..2138 26.8. Phase-S pecific and M ixture Conditions f or the E uler ian M odel (with the D ispersed Turbulenc e Mod- el)...........................................................................................................................................................2139 26.9. Phase-S pecific and M ixture Conditions f or the E uler ian M odel (with the P er-P hase Turbulenc e Mod- el)...........................................................................................................................................................2139 26.10. Open C hannel B oundar y Paramet ers f or the VOF M odel.................................................................2145 26.11. Slope Limit er D iscretiza tion Scheme ..............................................................................................2179 26.12. Paramet ers f or the C oalesc ence and B reakage Ker nels ...................................................................2195 26.13. Paramet ers f or the C oalesc ence and B reakage Ker nels ...................................................................2215 27.1. Macros for P opula tion B alanc e Variables D efined in sg_pb.h .........................................................2310 32.1. User-D efined Sc alar A llocations .......................................................................................................2365 32.2. User-D efined M emor y Allocations ...................................................................................................2365 33.1. User-D efined Sc alar A llocations .......................................................................................................2437 33.2. User-D efined M emor y Allocations ...................................................................................................2438 cxiRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.33.3. User-D efined Sc alar A llocations .......................................................................................................2467 33.4. User-D efined M emor y Allocations ...................................................................................................2467 33.5. User-D efined M emor y Allocations ...................................................................................................2477 33.6. User-D efined Sc alar A llocations .......................................................................................................2482 34.1. User-D efined Sc alars in MHD M odel.................................................................................................2498 34.2. MHD Vectors...................................................................................................................................2508 35.1. Source Terms and C orresponding UDFs ...........................................................................................2518 40.1. Standar d Views...............................................................................................................................2836 40.2. Numb ers of D ata Points Supp orted b y the P rime-F actor FFT A lgor ithm ............................................2900 40.3. Octave Band F requencies and Weigh tings ........................................................................................2907 42.1. Pressur e and Densit y Categor ies....................................................................................................2966 42.2. Velocity Categor y...........................................................................................................................2967 42.3. Temp erature,Radia tion , and Solidific ation/M elting Categor ies....................................................2968 42.4. Turbulenc e Categor y......................................................................................................................2969 42.5. Species ,Reac tions ,Pdf, and Premix ed C ombustion Categor ies.....................................................2972 42.6. NOx,Soot, and Stead y|Unstead y Statistics Categor ies...................................................................2974 42.7. Phases ,Discr ete Phase M odel,Granular P ressur e,Granular Temp erature, and Wall F ilm Categor- ies..........................................................................................................................................................2976 42.8. Properties Categor y.......................................................................................................................2979 42.9. Euler ian Wall F ilm Categor y...........................................................................................................2979 42.10. Sensitivities Categor y..................................................................................................................2981 42.11. Wall F luxes,User D efined Sc alars , and User D efined M emor y Categor ies...................................2982 42.12. Cell Inf o and Mesh Categor ies......................................................................................................2983 42.13. Mesh Categor y (Turbomachiner y-Specific Variables) ......................................................................2984 42.14. Residuals Categor y.......................................................................................................................2985 42.15. Derivatives Categor y....................................................................................................................2985 42.16. Potential Categor y.......................................................................................................................2986 42.17. Acoustics Categor y.......................................................................................................................2987 42.18. Structure Categor y.......................................................................................................................2988 43.1. Examples f or GPGPU s per M achine ..................................................................................................3048 43.2. Supp orted In terconnec ts for the Windo ws Platform.........................................................................3060 43.3. Available MPI s for Windo ws Platforms..............................................................................................3060 43.4. Supp orted MPI s for Windo ws Architectures (P er In terconnec t).........................................................3061 43.5. Supp orted In terconnec ts for Linux P latforms (P er Platform)..............................................................3065 43.6. Available MPI s for Linux P latforms...................................................................................................3066 43.7. Supp orted MPI s for Linux A rchitectures (P er In terconnec t)...............................................................3066 45.1. Variables On B oundar y Wall R egions ................................................................................................3211 45.2. Variables On C ell Z one R egions ........................................................................................................3211 45.3. Variables On P orous J ump B oundar y...............................................................................................3211 45.4. Licenses r equir ed for Fluen t as par t of a S ystem C oupling analy sis....................................................3232 1. Moving D omain M odels v s. Multiphase M odels ....................................................................................3965 2. Multiphase M odels v s.Turbulenc e Models ............................................................................................3965 3. Combustion M odels v s. Multiphase M odels ..........................................................................................3965 4. Moving D omain M odels v s.Turbulenc e Models ....................................................................................3966 5. Combustion M odels v s. Moving D omain M odels ...................................................................................3966 6. Combustion M odels v s.Turbulenc e Models ..........................................................................................3966 1. Summar y of B asic CHEMKIN-CFD P aramet ers .......................................................................................3990 2. Summar y of A dvanced CHEMKIN-CFD P aramet ers ...............................................................................3991 3. Diagnostic Output F iles C reated D uring a CHEMKIN-CFD R un...............................................................3994 4. Error M essages tha t May Be Printed t o the F luen t GUI ...........................................................................3996 5. Other E rror M essages in KINetics-log.txt ...................................................................................3999 1.1. Remot e Visualiza tion C lient En vironmen t Variables ............................................................................4033 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. cxiiUser's G uide2.1. Pressur e Far-Field, Mapping of A irflow Fluen t Icing B oundar y Condition in to Fluen t & FENSAP B oundar y Conditions ..............................................................................................................................................4066 2.2.Velocity Inlet , Mapping of A irflow Fluen t Icing B oundar y Condition in to Fluen t & FENSAP B oundar y Conditions ..............................................................................................................................................4067 2.3. Mass F low Inlet , Mapping of A irflow Fluen t Icing B oundar y Condition in to Fluen t & FENSAP B oundar y Conditions ..............................................................................................................................................4068 2.4. Pressur e Inlet , Mapping of A irflow Fluen t Icing B oundar y Condition In to Fluen t Boundar y Conditions ..4068 cxiiiRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User's G uideRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. cxivPart I: Getting S tarted The sec tion descr ibes getting star ted with ANSY S Fluen t. •Introduc tion t o ANSY S Fluen t (p.3), introduc tion t o ANSY S Fluen t . •Basic S teps f or CFD A naly sis using ANSY S Fluen t (p.25), basic st eps f or CFD analy sis using ANSY S Fluen t . •Guide t o a Succ essful S imula tion U sing ANSY S Fluen t (p.31), guide t o a succ essful simula tion using ANSY S Fluen t . •Starting and Ex ecuting ANSY S Fluen t (p.33), provides instr uctions f or star ting and e xecuting ANSY S Fluen t . •Glossar y of Terms (p.63), this glossar y contains a listing of t erms c ommonly used thr oughout the ANSY S Fluen t do cumen tation.Chapt er 1: Introduc tion t o ANSY S Fluen t ANSY S Fluen t is a sta te-of-the-ar t comput er pr ogram f or mo deling fluid flo w, hea t transf er, and chem- ical reactions in c omple x geometr ies. ANSY S Fluen t is wr itten in the C c omput er language and mak es full use of the fle xibilit y and p ower offered b y the language . Consequen tly, true d ynamic memor y allo cation, efficien t da ta str uctures, and flexible solv er control ar e all p ossible . In addition, ANSY S Fluen t uses a clien t/ser ver ar chitecture, which enables it t o run as separ ate simultaneous pr ocesses on clien t deskt op w orksta tions and p owerful comput e ser vers.This ar chitecture allo ws for efficien t execution, interactive control, and c omplet e flexibilit y between diff erent types of machines or op erating sy stems . ANSY S Fluen t provides c omplet e mesh fle xibilit y, including the abilit y to solv e your flo w pr oblems using unstr uctured meshes tha t can b e gener ated ab out c omple x geometr ies with r elative ease . Supp orted mesh t ypes include 2D tr iangular/quadr ilateral, 3D t etrahedr al/he xahedr al/p yramid/w edge/p olyhedr al, and mix ed (h ybrid) meshes . ANSY S Fluen t also enables y ou t o refine or c oarsen y our mesh based on the flo w solution. You c an r ead y our mesh in to ANSY S Fluen t, or, for 3D geometr ies, create your mesh using the meshing mode of F luen t (see the Fluen t User’s Guide (p.1) for fur ther details). All remaining op erations ar e performed within the solution mo de of F luen t, including setting b oundar y conditions , defining fluid properties, executing the solution, refining the mesh, and p ostpr ocessing and viewing the r esults . The ANSY S Fluen t ser ial solv er manages file input and output , data st orage, and flo w field c alcula tions using a single solv er pr ocess on a single c omput er. ANSY S Fluen t also uses a utilit y called cortex tha t manages ANSY S Fluen t’s user in terface and basic gr aphic al func tions . ANSY S Fluen t’s par allel solv er enables y ou t o comput e a solution using multiple pr ocesses tha t ma y be executing on the same c om- puter, or on diff erent comput ers in a net work. The ANSY S Fluen t solv er manages file input and output , data st orage, and flo w field c alcula tions . Pro- cessing in volves an in teraction b etween ANSY S Fluen t, a host pr ocess, and one or mor e comput e-no de processes . ANSY S Fluen t interacts with the host pr ocess and the c omput e no de(s) using a utilit y called cortex , which manages ANSY S Fluen t’s user in terface and basic gr aphic al func tions . 3Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Figur e 1.1: ANSY S Fluen t Archit ecture ANSY S Fluen t’s ser ial solv er uses a single c omput e no de, wher eas the par allel solv er comput es a solution using multiple c omput e no des tha t ma y be executing on the same c omput er, or on diff erent comput ers in a net work. For mor e inf ormation ab out ANSY S Fluen t’s par allel pr ocessing c apabilities , message passing in terfaces (MPI), and so on, refer to Parallel P rocessing (p.3045 ) in the User's G uide (p.1). All func tions r equir ed t o comput e a solution and displa y the r esults ar e acc essible in ANSY S Fluen t through an in teractive in terface. For mor e inf ormation, see the f ollowing sec tions: 1.1.The ANSY S Product Impr ovemen t Program 1.2. Program C apabilities 1.3. Known Limita tions in ANSY S Fluen t 2019 R3 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4Introduction t o ANSY S Fluen t1.1. The ANSY S Produc t Impr ovemen t Program This pr oduc t is c overed b y the ANSY S Produc t Impr ovemen t Program, which enables ANSY S, Inc., to collec t and analyz e anonymous usage da ta reported b y our sof tware without aff ecting y our w ork or produc t performanc e. Analyzing pr oduc t usage da ta helps us t o understand cust omer usage tr ends and pa tterns, interests , and qualit y or p erformanc e issues .The da ta enable us t o de velop or enhanc e produc t features tha t better addr ess y our needs . How to Participa te The pr ogram is v olun tary.To par ticipa te, selec t Yes when the P roduc t Impr ovemen t Program dialo g app ears . Only then will c ollec tion of da ta for this pr oduc t begin. How the P rogram Works After y ou agr ee t o par ticipa te, the pr oduc t collec ts anon ymous usage da ta dur ing each session. When you end the session, the c ollec ted da ta is sen t to a secur e ser ver acc essible only t o author ized ANSY S emplo yees. After ANSY S receives the da ta, various sta tistic al measur es such as distr ibutions , coun ts, means , medians , mo des, etc., are used t o understand and analyz e the da ta. Data We Collec t The da ta w e collec t under the ANSY S Produc t Impr ovemen t Program ar e limit ed.The t ypes and amoun ts of c ollec ted da ta v ary from pr oduc t to pr oduc t.Typic ally, the da ta fall in to the c ategor ies list ed her e: Hardware: Information ab out the har dware on which the pr oduc t is r unning , such as the: •brand and t ype of CPU •numb er of pr ocessors a vailable •amoun t of memor y available •brand and t ype of gr aphics c ard System: Configur ation inf ormation ab out the sy stem the pr oduc t is r unning on, such as the: •operating sy stem and v ersion •coun try code •time z one •language used •values of en vironmen t variables used b y the pr oduc t Session: Characteristics of the session, such as the: •interactive or ba tch setting •time dur ation •total CPU time used 5Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.The ANSY S Product Impr ovemen t Program•produc t license and lic ense settings b eing used •produc t version and build iden tifiers •command line options used •numb er of pr ocessors used •amoun t of memor y used •errors and w arnings issued Session A ctions: Coun ts of c ertain user ac tions dur ing a session, such as the numb er of : •projec t saves •restar ts •meshing , solving , postpr ocessing , etc., actions •times the H elp sy stem is used •times wizar ds ar e used •toolbar selec tions Model: Statistics of the mo del used in the simula tion, such as the: •numb er and t ypes of en tities used , such as no des, elemen ts, cells, surfaces, primitiv es, etc. •numb er of ma terial types, loading t ypes, boundar y conditions , species , etc. •numb er and t ypes of c oordina te sy stems used •system of units used •dimensionalit y (1-D , 2-D , 3-D) Analysis: Characteristics of the analy sis, such as the: •physics t ypes used •linear and nonlinear b ehaviors •time and fr equenc y domains (sta tic, steady-sta te, transien t, mo dal, har monic , etc.) •analy sis options used Solution: Characteristics of the solution p erformed , including: •the choic e of solv ers and solv er options •the solution c ontrols used , such as c onvergenc e criteria, precision settings , and tuning options •solv er sta tistics such as the numb er of equa tions , numb er of load st eps, numb er of design p oints, etc. Specialt y: Special options or f eatures used , such as: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 6Introduction t o ANSY S Fluen t•user-pr ovided plug-ins and r outines •coupling of analy ses with other ANSY S pr oduc ts Data We Do Not C ollec t The P roduc t Impr ovemen t Program do es not collec t an y inf ormation tha t can iden tify y ou p ersonally , your c ompan y, or y our in tellec tual pr operty.This includes , but is not limit ed t o: •names , addr esses , or user names •file names , par t names , or other user-supplied lab els •geometr y- or design-sp ecific inputs , such as c oordina te values or lo cations , thick nesses , or other dimen- sional v alues •actual v alues of ma terial pr operties, loadings , or an y other r eal-v alued user-supplied da ta In addition t o collec ting only anon ymous da ta, we mak e no r ecord of wher e we collec t da ta fr om. We ther efore cannot asso ciate collec ted da ta with an y sp ecific cust omer , compan y, or lo cation. Opting Out of the P rogram You ma y stop your par ticipa tion in the pr ogram an y time y ou wish. To do so , selec t ANSY S Produc t Impr ovemen t Program from the H elp menu . A dialo g app ears and asks if y ou w ant to continue par ti- cipa ting in the pr ogram. Selec t No and then click OK. Data will no longer b e collec ted or sen t. The ANSY S, Inc., Privacy Polic y All ANSY S pr oduc ts ar e covered b y the ANSY S, Inc.,Privacy Policy. Frequen tly A sked Q uestions 1. Am I r equir ed t o par ticipat e in this pr ogram? No, your par ticipa tion is v olun tary.We enc ourage y ou t o par ticipa te, however, as it helps us cr eate produc ts tha t will b etter meet y our futur e needs . 2. Am I aut omatic ally enr olled in this pr ogram? No.You ar e not enr olled unless y ou e xplicitly agr ee t o par ticipa te. 3. Does par ticipating in this pr ogram put my int ellec tual pr operty at r isk of b eing c ollec ted or disc overed b y ANSY S? No.We do not c ollec t an y pr ojec t-sp ecific , compan y-sp ecific , or mo del-sp ecific inf ormation. 4. Can I st op par ticipating e ven af ter I agr ee t o par ticipat e? Yes, you c an st op par ticipa ting a t an y time .To do so , selec t ANSY S Produc t Impr ovemen t Program from the H elp menu . A dialo g app ears and asks if y ou w ant to continue par ticipa ting in the pr ogram. Selec t No and then click OK. Data will no longer b e collec ted or sen t. 5. Will par ticipation in the pr ogram slo w the p erformanc e of the pr oduc t? 7Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.The ANSY S Product Impr ovemen t ProgramNo, the da ta collec tion do es not aff ect the pr oduc t performanc e in an y signific ant way.The amoun t of da ta collec ted is v ery small. 6. How fr equentl y is data c ollec ted and sent t o ANSY S ser vers? The da ta is c ollec ted dur ing each use session of the pr oduc t.The c ollec ted da ta is sen t to a secur e server onc e per session, when y ou e xit the pr oduc t. 7. Is this pr ogram a vailable in all ANSY S pr oduc ts? Not a t this time , although w e ar e adding it t o mor e of our pr oduc ts at each r elease .The pr ogram is available in a pr oduc t only if this ANSY S Produc t Impr ovement P rogram descr iption app ears in the produc t do cumen tation, as it do es her e for this pr oduc t. 8. If I enr oll in the pr ogram f or this pr oduc t, am I aut omatic ally enr olled in the pr ogram f or the other ANSY S pr oduc ts I use on the same machine? Yes.Your enr ollmen t choic e applies t o all ANSY S pr oduc ts you use on the same machine . Similar ly, if you end y our enr ollmen t in the pr ogram f or one pr oduc t, you end y our enr ollmen t for all ANSY S produc ts on tha t machine . 9. How is enr ollment in the P roduc t Impr ovement P rogram det ermined if I use ANSY S pr oduc ts in a clust er? In a clust er configur ation, the P roduc t Impr ovemen t Program enr ollmen t is det ermined b y the host machine setting . 10. Can I easil y opt out of the P roduc t Impr ovement P rogram f or all clients in my net work installation? Yes. Perform the f ollowing st eps on the file ser ver: a.Naviga te to the installa tion dir ectory:[Drive:]\v195\commonfiles\globalsettings b.Open the file ANSY SProduc tImpr ovemen tProgram.tx t. c.Change the v alue fr om "on" t o "off " and sa ve the file . 1.2. Program C apabilities When in meshing mo de, ANSY S Fluen t func tions as a r obust unstr uctured-v olume-mesh gener ator (see Meshing M ode C apabilities (p.69) in the Fluen t User’s Guide (p.1) for fur ther details). When in solution mode, Fluen t allo ws you t o simula te the f ollowing: •2D planar , 2D axisymmetr ic, 2D axisymmetr ic with swir l (rotationally symmetr ic), and 3D flo ws •Flows on quadr ilateral, triangular , hexahedr al (br ick), tetrahedr al, wedge , pyramid , polyhedr al, and mix ed elemen t meshes •Steady-sta te or tr ansien t flo ws •Incompr essible or c ompr essible flo ws, including all sp eed r egimes (lo w subsonic , transonic , sup ersonic , and hypersonic flo ws) •Inviscid , laminar , and turbulen t flo ws •Newtonian or non-N ewtonian flo ws Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 8Introduction t o ANSY S Fluen t•Ideal or r eal gases •Heat transf er, including f orced, natural, and mix ed c onvection, conjuga te (solid/fluid) hea t transf er, and r a- diation •Chemic al sp ecies mixing and r eaction, including homo geneous and het erogeneous c ombustion mo dels and sur face dep osition/r eaction mo dels •Free sur face and multiphase mo dels f or gas-liquid , gas-solid , and liquid-solid flo ws •Lagr angian tr ajec tory calcula tions f or disp ersed phase (par ticles/dr oplets/bubbles), including c oupling with continuous phase and spr ay mo deling •Cavitation mo del simula tions •Melting/solidific ation applic ations using the phase change mo del •Porous media with non-isotr opic p ermeabilit y, iner tial r esistanc e, solid hea t conduc tion, and p orous-fac e pressur e jump c onditions •Lump ed par amet er mo dels f or fans , pumps , radia tors, and hea t exchangers •Acoustic mo dels f or pr edic ting flo w-induc ed noise •Iner tial (sta tionar y) or non-iner tial (r otating or acc elerating) r eference frames •Multiple mo ving fr ames using multiple r eference frame (MRF) and sliding mesh options •Mixing-plane mo del simula tions of r otor-sta tor in teractions , torque c onverters, and similar turb omachiner y applic ations with options f or mass c onser vation and swir l conser vation •Dynamic mesh mo del simula tions f or domains with mo ving and def orming meshes •Volumetr ic sour ces of mass , momen tum, hea t, and chemic al sp ecies •Simula tions tha t use a ma terial pr operty da tabase •Simula tions in which the design is r evised or optimiz ed, using the adjoin t solv er or the mesh mor pher/optimiz er •Simula tions cust omiz ed b y user-defined func tions •Dynamic (t wo-w ay) coupling with GT-PO WER and WAVE •Simula tions tha t use the f ollowing add-on mo dules: –Battery mo dule –Continuous fib er mo dule –Macroscopic par ticle mo del (MPM) mo dule –Fuel c ell mo dules –Magnet ohydrodynamics (MHD) mo dule –Popula tion balanc e mo dule 9Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Program C apabilities•Fluen t as a S erver (do cumen ted separ ately) ANSY S Fluen t is ideally suit ed f or inc ompr essible and c ompr essible fluid-flo w simula tions in c omple x geometr ies. ANSY S Fluen t’s par allel solv er enables y ou t o comput e solutions f or c ases with v ery lar ge meshes on multiple pr ocessors , either on the same c omput er or on diff erent comput ers in a net work. ANSY S, Inc. also off ers other solv ers tha t addr ess diff erent flo w regimes and inc orporate alt ernative physical mo dels . Additional CFD pr ograms fr om ANSY S, Inc. include CFX, ANSY S Icepak, and ANSY S Polyflo w. 1.3. Known Limita tions in ANSY S Fluen t 2019 R3 This sec tion lists limita tions tha t are known t o exist in ANSY S Fluen t.Where possible , suggest ed w ork- arounds ar e pr ovided . •File imp ort/export (for a list of supp orted files , refer to the table in this sec tion, under Third-par ty sof tware) –(Windo ws only) ANSY S Fluen t cannot imp ort CGNS files gr eater than 2 GB in siz e. (105076) –Due t o a 3r d par ty issue , Mechanic al APDL r esults files using sparsific ation file c ompr ession (default at ANSY S Release 2019 R3) c annot b e read in to Fluen t and ma y cause the session t o close une xpec- tedly . As a w orkaround , you c an un-c ompr ess these files using the *XPL c ommand in M echanic al APDL (r efer to the UNC OMP value of the COPY action descr ibed in X Commands in the Command Referenc e) –If you change the File S torage Options settings in the Autosa ve dialo g box, the solution hist ory will b e lost. –When e xporting EnS ight Case G old files f or tr ansien t simula tions , the solv er cannot b e swit ched b etween serial and par allel, and the numb er of c omput e no des c annot b e changed f or a giv en par allel r un. Other wise , the e xported EnS ight Case G old files f or each time st ep will not b e compa tible . –EnSight export with t opology changes is not supp orted. –To pr operly view F ieldview U nstr uctured (.fvuns ) results fr om a ser ial or par allel ANSY S Fluen t simula tion: →Mesh files must b e exported using the fieldview-unstruct-grid text command . →Mesh and da ta files should all b e exported fr om par allel ANSY S Fluen t sessions with the same numb er of no des. –Tecplot file imp ort do es not supp ort the Tecplot360 file f ormat. –The maximum numb er of pr ofiles tha t can b e read in to a single F luen t session is 50. –The P ARALLEL INDEPENDENT mo de f or Hier archic al D ata Format file I/O is k nown t o exhibit slo w wr ite performanc e. On par allel file sy stems , consider using the P ARALLEL C OLLECTIVE mo de when wr iting HDF files . On other net work file sy stems , consider using the HOST or NODE0 mo de. –If you ar e acc essing a file using a U niversal N aming C onvention (UNC) pa th, you must ensur e tha t you have permission t o acc ess t o all of the f olders in the pa th or y ou will not b e able t o op en the file . –(Windo ws only) The file filt er available in the Selec t File dialo g box ma y not w ork as e xpected, requir ing you t o manually selec t the desir ed file(s) without filt ering aid . (174291) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 10Introduction t o ANSY S Fluen t–Files wr itten b y ANSY S pr oduc ts do not supp ort synchr oniza tion with M icrosof t's OneD rive file hosting service. (187717 / 74067) –When y ou ha ve read a mesh or c ase file in F luen t, you c annot then app end a c ase file tha t uses the Hier- archic al D ata Format (HDF)—tha t is, a .cas.h5 file.Workaround: If one of the c ase files do es not use HDF , then r ead the HDF c ase file first and app end the other file . (183851) •Mesh –Boundar y zone e xtrusion is not p ossible fr om fac es tha t ha ve hanging no des. –For simula tions tha t involve the F luen t, Mechanic al, and M eshing applic ations , meshing pr oblems c an arise in instanc es wher e ther e are multiple r egions and c ontacts between them. In F luen t, a zone c an only exist in a single c ontact region. The M echanic al and M eshing applic ations b oth use a diff erent appr oach concerning c ontact regions when c ompar ed t o Fluen t. –ANSY S Fluen t do es not supp ort FSI da ta mapping of edges and , ther efore, it is not supp orted in 2D . –At non-c onformal in terfaces, the Matching option is no longer allo wed with the Mapp ed option. When opening a c ase set up in a pr evious r elease with b oth options enabled , you will b e pr ompt ed t o recreate the in terface without the Matching option. –If your mesh t opology has a st ep-wise pr ism mesh near the w alls, do not use no de-based gr adien ts with MUSCL. –For shell c onduc tion c ases in which y ou ha ve performed adaption using the p olyhedr al unstr uctured mesh adaption (PUMA) metho d, ANSY S Fluen t ma y termina te abnor mally if y ou a ttempt t o impr ove mesh qualit y in a par allel session with multiple c omput e no des.Workaround: After adapting with the PUMA metho d, you must sa ve the c ase file and r ead it back in to Fluen t before impr oving mesh qualit y. •Models –Fluen t allo ws you t o selec t via S ystem C oupling as a ther mal b oundar y condition option on the child z one of a sliding in terface.This is not supp orted, and the .scp file c orrectly suppr esses tha t region fr om c oupling . –ANSY S Fluen t supp orts the C hemk in II f ormat for Opp dif flamelet imp ort only . –The sur face-to-sur face (S2S) r adia tion mo del do es not w ork with mo ving/def orming meshes . –The DPM w ork pile algor ithm is not c ompa tible with the w all film b oundar y condition. –For tr ansien t Lagr angian multiphase analy sis with DPM unst eady par ticle tr acking, atomiz er or c one injec- tions will r elease par ticles fr om the same p osition r ather than fr om r andom p ositions if Particle Time Step S ize is smaller than Time S tep S ize.To use r andom star ting p oints for the par ticles , enter the f ollowing Scheme c ommands in the ANSY S Fluen tconsole: (rpsetvar 'dpm/random/seed-timestep-corrected? #t) (dpm-parameters-changed) Note tha t this change will also aff ect par ticle tr ajec tories if st ochastic tr acking, par ticle br eakup, or other mechanisms tha t involve random numb ers ar e used . (176638) 11Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Known Limita tions in ANSY S Fluen t 2019 R3–The shell c onduc tion mo del is not applic able on mo ving w alls. –The hea t exchanger mo del is not c ompa tible with mesh adaption. –The F luen t/ANSY S Reaction D esign KIN etics c oupling is not a vailable on the win64 pla tform. –DO-Ener gy coupling is r ecommended f or lar ge optic al thick ness c ases (> 10) only . –FMG initializa tion is not a vailable with the shell c onduc tion mo del. –FMG initializa tion is not c ompa tible with the unst eady solv er. –The MHD mo dule is not c ompa tible with E uler ian multiphase mo dels . –Bounded 2nd or der discr etiza tion in time is not c ompa tible with mo ving and def orming meshes . –When simula ting p orous media, the v alue of the Porosit y (defined in the Fluid dialo g box) cannot b e 0 or 1 (tha t is, it must b e in b etween these v alues) if the non-equilibr ium ther mal mo del is enabled . –When simula ting p orous media, the non-equilibr ium ther mal mo del is not supp orted with r adia tion and/or multiphase mo dels . –For p orous media simula tions , the r elative velocity resistanc e formula tion is not supp orted with axisym- metr ic-swir l when ther e are non-z ero swir l resistanc es. –The junc tion of a w all with shell c onduc tion enabled and a non-c onformal c oupled w all is not supp orted. Such a junc tion will not b e ther mally c onnec ted, tha t is, ther e will b e no hea t transf er b etween the shell and the mesh in terface wall. –After you enable the E uler ian Wall F ilm mo del, Fluen t will not allo w you t o sa ve the mesh mo dific ations , such as separ ating c ells, extruding fac e zones , and changing the c ell z ones t ype. If you w ant to mo dify the mesh in F luen t, be sur e to complet e all mesh op erations pr ior t o enabling the E uler ian Wall F ilm model. –The Transition SST mo del (also k nown as the γ-Reθ mo del) is not G alilean in variant and should ther efore not b e applied t o sur faces tha t mo ve relative to the c oordina te sy stem f or which the v elocity field is comput ed; for such c ases , the In termitt ency Transition mo del (also k nown as the γ mo del) should b e used instead. –In simula tions tha t use the discr ete phase mo del, par ticle mass ma y be lost when simula tion of tr ansien t particles r eleased with c onstan t par cel siz e is c ombined with aut o-sa ve of c ase files . –User-defined w all func tions ar e not c ompa tible with the E uler ian multiphase f ormula tion and c annot b e used . –The view fac tor files gener ated as par t of a sur face-to-sur face radia tion mo del c alcula tion f or v ersion 16.0 or 16.1 of F luen t ma y not b e compa tible with new er versions if the Matching option w as enabled f or a mapp ed in terface. For an y case file with such a setup , you must r ecomput e the view fac tors in the new er version t o ensur e correct results . •Parallel pr ocessing –The discr ete transf er radia tion mo del (DTRM) is una vailable in the par allel solv er. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 12Introduction t o ANSY S Fluen t–Mellano x OFED v ersion 1.5.3–1.0.0 is k nown t o cause r andom cr ashes or star tup issues in F luen t when using c ore coun ts gr eater than appr oxima tely 64. The last k nown stable M ellano x version is 1.5.2. You may use either of the f ollowing as a w orkaround: →Revert to OFED 1.5.2. →Set the v alue of log_num_mtt to 24 in the mlx4_core driver on all machines . –IBM MPI do es not supp ort running in par allel in an o verload c ondition (using mor e cores than ar e ph ysically available on a machine). For p erformanc e reasons , running in an o verload c ondition is gener ally not r e- commended . However, if it is r equir ed t o run o verloaded , then y ou c an use In tel MPI (-mpi=intel ) or Open MPI (-mpi=openmpi ). –The v ersion of IBM MPI tha t is distr ibut ed with F luen t is no w limit ed t o a maximum of 4096 pr ocesses f or a single simula tion. For higher c ore coun ts, an additional lic ense is r equir ed. Refer to IBM P latform MPI with High (>4096) P rocess C oun t in the ANSY S, Inc . Installation G uides for mor e inf ormation. –Note tha t on sy stems using lar ge pages f or memor y allo cation (such as C ray), the vir tual memor y usage reported b y Fluen t ma y be much higher than ac tual memor y used . In this c ase r esiden t memor y (also reported b y Fluen t) is a mor e reliable guide . –Degener ate contact points ar e known t o cause t opological mesh c onnec tivit y issues in par allel. Degener ate contact points ar e no des tha t are shar ed b y 2 or mor e cell z ones tha t do not shar e fac es. Fluen t can det ect degener ate contact points in ser ial via a mesh check with the mesh check v erbosity set gr eater than 0. If a case has gener ate contact points then y ou must use the f ollowing c ommand b efore reading the c ase for pr oper par allel handling of such c ontact points. (rpsetvar 'parallel/add-dgcp-to-int-or-corner?) –The E uler ian Wall-film mo del is not c ompa tible with the DPM D omain option of the h ybrid par allel DPM tracking. For such mo del c ombina tion, the Use DPM D omain option must b e disabled in the Parallel tab of the Discr ete Phase M odel dialo g box. –The F luen t process binding (affinit y) setting is not supp orted f or Windo ws machines with mor e than 64 cores tha t are using the IBM MPI c ommunic ation libr ary, which ma y incr ease pr ocessing time . As a w ork- around , you c an use In tel MPI or disable h yper-thr eading (if the machine has In tel pr ocessors) t o lower the c ore coun t to be equal t o or b elow 64. –Starting in v ersion 18.0, ANSY S Fluen t will r equir e appr oxima tely 60 MB mor e memor y per no de pr ocess compar ed t o version 17.0–17.2. –If you ha ve Op enSSH inside C:\windo ws\sy stem32 and w ant to run a mix ed Windo ws-Linux simu- lation, Fluen t ma y not b e able t o lo cate and e xecut e the ssh c ommand , and the f ollowing w arning will b e pr inted: 'ssh' is not recognized as an internal or external command, operable program or batch file. You must sp ecify the pa th of the ac tual ssh t o be used: launching fr om the c ommand line , use the -rsh option (f or e xample ,-rsh=c:\cygwin64\bin\ssh.exe ); using F luen t Launcher , selec t Other from the Remot e Spawn C ontrol list in the Remot e tab and en ter the pa th in the t ext box (for e xample ,c:\cygwin64\bin\ssh.exe ). 13Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Known Limita tions in ANSY S Fluen t 2019 R3In addition, you should add the lo cation of ssh executable t o the b eginning of the P ATH en viron- men t variable . (184255/176971) –The In tel MPI v ersion up grade in F luen t release 2019 R1 br eaks c ompa tibilit y with older r eleases on Win- dows.Workaround: To swit ch b etween r unning older r eleases and the la test r elease on a clust er, you must mak e sur e tha t the appr opriate ser vices ha ve been c onfigur ed t o run b y the administr ator as f ollows: →To swit ch fr om old t o new (f or e xample , 19.2 t o 2019 R1), run the f ollowing c ommand on all no des from the c ommand pr ompt with administr ator pr ivileges: “C:\Program Files (x86)\IntelSWTools\compilers_and_libraries_2018.3.210\windows\mpi\intel64\bin\ hydra_service.exe” -install →To swit ch fr om new t o old (f or e xample , 2019 R1 t o 19.2), run the f ollowing c ommand on all no des from the c ommand pr ompt with administr ator pr ivileges: “C:\Program Files (x86)\IntelSWTools\compilers_and_libraries_2017.4.210\windows\mpi\intel64\bin\ hydra_service.exe” -install After installing b oth v ersions of In tel MPI, the I_MPI_R OOT en vironmen t variable should b e delet ed from all no des. (180338) •Platform supp ort and dr ivers –On Windo ws Server OS, ANSY S Fluen t supp orts only MS MPI f or par allel r uns. Installing an y other unsup- ported MPI libr aries (IBM MPI or In tel MPI) will r esult in c onflic ts. –On Windo ws 7 and la ter, installing ANSY S Fluen t on an y dr ive other than C: may result in issues ar ising from spac es in the pa thname not getting c onverted t o shor t file names .This is the r esult of a change in the default v alue f or NtfsDisable8dot3NameCreation star ting with Windo ws 7. If you need t o install ANSY S Fluen t on an y dr ive other than C: you must r un the f ollowing c ommand prior to installing ANSY S Fluen t: fsutil 8dot3name set 0 wher e is the tar get dr ive lett er including the c olon (f or e xample ,D:). –The minimum OS r equir emen ts for Linux ar e SLES 11 SP2 or RHEL 6. –The pa thname length t o the cpr opep.so libr ary (including the lib name) is limit ed t o 80 char acters. (Linux Opt eron clust er using Infiniband in terconnec t only .) –On Linux pla tforms, including a spac e char acter in the cur rent working dir ectory pa th is not supp orted. –If you ar e installing ANSY S Fluen t 2019 R3 on a Windo ws machine tha t alr eady has one or mor e pr evious versions of ANSY S Fluen t, then af ter installing IBM MPI and In tel MPI libr aries fr om the pr erequisit es, mak e sure to delet e the en vironmen t variables MPI_R OOT (for IBM MPI) and I_MPI_R OOT (for In tel MPI). Other wise ther e will b e a c onflic t while r unning pr evious ANSY S Fluen t versions in par allel mo de. –Remot e Solver Facilit y (RSF) is no longer supp orted in ANSY S Fluen t. –Itanium pla tform (lnia64) is no longer supp orted. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 14Introduction t o ANSY S Fluen t–ANSY S Fluen t uses se veral TCP/IP p orts for communic ations and er ror handling . Port conflic ts with other programs tr ying t o use the same p orts ar e handled b y ANSY S Fluen t and gener ate warnings similar t o the f ollowing: 428: mpt_accept: warning: incorrect exercise message "GET /" from 10.1.0.188 on port 56564 Long r unning lar ge sessions ar e mor e pr one t o gener ating such w arnings , but these ar e gener ally safe for y ou t o ignor e. –When using the default MPI ( ibmmpi ) on some new er har dware the f ollowing message ma y app ear when exiting the F luen t session. hwloc has encountered what looks like an error from the operating system. object (Socket cpuset 0xff00ffff) intersection without inclusion! Error occurred in topology.c line 758 Please report this error message to the hwloc user's mailing list, along with any relevant topology information from your platform. This message is fr om the har dware lo cality libr ary used b y IBM MPI. You c an set the f ollowing en- vironmen t variable t o hide this message , or swit ch t o In tel MPI. HWLOC_HIDE_ERRORS=1 –If you lo ck the c omput er scr een b efore the F luen t graphics ar e initializ ed, the F luen t session will not launch if you ar e using the Op enGL gr aphics dr iver.To avoid this issue with the Op enGL dr iver, you c an use the alternative dr ivers x11 or null for Linux/unix and msw or null for Windo ws.You c an sp ecify an alt ernate graphics dr iver either b y defining it in the HOOPS_PICTURE environmen t variable or using the -driver Fluen t command line option. –Fluen t ma y termina te abnor mally dur ing launch when r unning on C ommunit y En terprise OS (C entOS) 7.3 or R ed Ha t En terprise Linux (RHEL) 7.3 when DISPL AY is set t o a Virtual N etwork Computing ( VNC) session. To attempt t o resolv e this , verify tha t you ar e using a supp orted gr aphics c ard and up date the graphics c ard dr ivers (dir ectly fr om the gr aphics c ard vendor w ebsit e). If the issue p ersists , you c an do one of the f ollowing: set the DISPL AY to a lo cal machine; set the LD_PRELOAD environmen t variable t o /usr/lib64/libstdc++.so.6 ; or use the alt ernative dr ivers x11 or null (either b y defining it in the HOOPS_PICTURE environmen t variable or using the -driver Fluen t command line option). –When launching F luen t (in meshing mo de or solution mo de) on Windo ws with the default IBM MPI, if the installa tion pa th is v ery long , then y ou ma y receive the f ollowing er ror message and b e forced t o use the Task M anager t o end the F luen t applic ation: mpirun.exe has stopped working As a w orkaround , you c an a void this issue b y using the In tel MPI (not e tha t in F luen t Launcher , you c an only r evise the MPI as par t of par allel settings , so f or a ser ial c ase y ou need t o selec t par- allel with a single pr ocessor); or, you c an tr y minimizing the numb er of char acters in the F luen t installa tion pa th. (153945) •Remot e displa y –Connec ting or disc onnec ting a VPN net work while r unning a F luen t simula tion will r esult in a failur e because of changes t o the net work interface. 15Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Known Limita tions in ANSY S Fluen t 2019 R3–If you e xperienc e an abnor mal t ermina tion when r unning F luen t via a r emot e displa y, check y ou gr aphics card to ensur e tha t you ha ve a mo dern pr ofessional gr aphics c ard tha t is up-t o-da te (tha t is, the la test updated dr iver for tha t card, which is a vailable on the c ompan y's w ebsit e). If your sy stem do es not meet the gr aphics c ard requir emen ts, launch F luen t using a c omplet ely sof tware-based dr iver, such as MSW (Windo ws) or X11 (Linux). –(Exceed onD emand and VNC Viewer) The Num L ock numb er keys and ar rows ma y not func tion in the graphic al user in terface or c onsole . As a w orkaround , you c an define the XKB_DEFAULT_RULES envir- onmen t variable set equal t o base , which r esolv es the ar row keys' func tionalit y. Numb er en tries must still b e complet ed using the numb er keys at the t op of the standar d keyboard. (172528) –(Linux only) When r unning ANSY S Fluen t using the Virtual N etwork Computing ( VNC), Nice DCV , or Ex ceed on D emand (E oD) applic ations , you ma y experienc e une xpected er ror messages due t o a 3r d par ty issue . To resolv e these er rors, install the f ollowing pack ages: (185796) →xcb-util-wm-0.4.1-5.el6.x86_64 →xcb-util-k eysyms-0.4.0-1.el6.x86_64 →xcb-util-0.4.0-2.2.el6.x86_64 →compa t-xcb-util-0.4.0-2.2.el6.x86_64 →xcb-util-image-0.4.0-3.el6.x86_64 –(Linux only) On some clust ers without acc elerated gr aphics , Fluen t ma y not acc ept k eyboard inputs . If you enc oun ter this b ehavior, set the QT_XKB_CONFIG_ROOT environmen t variable equal t o /usr/share/X11/xkb . •Cell Z ones and B oundar y Conditions –A reference frame is alw ays displa yed a t its initial sta te (p osition and or ientation) when displa yed fr om the Referenc e Frame dialo g box.While r unning a tr ansien t simula tion f or multiple time st eps, a reference frame is displa yed a t its cur rent sta te. After the c alcula tion is c omplet ed, if you op en the Referenc e Frame dialo g box and displa y it, the r eference frame tr iad will mo ve back t o its initial sta te. (184248) –Clicking OK within the Referenc e Frame dialo g box will r eset a r eference frame t o its initial sta te. If you do not in tend t o mak e changes t o a r eference frame , leave the dialo g box by click ing Canc el. (184248) •Reference Frames –Fluid z ones designa ted as 3D fan z ones c annot ha ve non-c onformal in terfaces. •Solver –The absolut e and r elative velocity formula tions ma y yield diff erent results in c ases wher e a str ong r eversal of flo w exists a t a pr essur e outlet b oundar y. –The non-it erative time ad vancemen t (NIT A) solv er is applic able with only a limit ed set of mo dels . See the ANSY S Fluen t User's G uide f or mor e details . –NITA (using fr actional time st ep metho d) is not c ompa tible with p orous media. –The following mo dels ar e not a vailable f or the densit y-based solv ers: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 16Introduction t o ANSY S Fluen t→Volume-of-fluid ( VOF) mo del →Multiphase mix ture mo del →Euler ian multiphase mo del →Non-pr emix ed c ombustion mo del →Premix ed c ombustion mo del →Partially pr emix ed c ombustion mo del →Comp osition PDF tr ansp ort mo del →Soot mo del →Rosseland r adia tion mo del →Melting/solidific ation mo del →Enhanc ed C oher ent Flamelet mo del →Iner t mo del: transp ort of iner t species (EGR in IC engines) →Dense discr ete phase mo del →Shell c onduc tion mo del →Floating op erating pr essur e →Spark ignition and aut o-ignition mo dels →Physical velocity formula tion f or p orous media →Selec tive multigr id (SAMG) –The pr essur e-based c oupled solv er is not a vailable with the f ollowing f eatures: →Fixed v elocity –On some Linux pla tforms, pressing Ctrl+C will not in terrupt the solution. A suggest ed w orkaround is t o use the check point mechanism in F luen t to sa ve files and/or e xit F luen t. (Check pointing an ANSY S Flu- ent Simula tion in the Fluent U ser's G uide (p.59)) –In certain c ases with t etrahedr al or h ybrid meshes , the use of the L east-S quar es C ell B ased gr adien t metho d in c ombina tion with the c ell-t o-cell limit er ma y cause div ergenc e. If this is obser ved, it is r ecom- mended tha t you either change the gr adien t metho d to Green-G auss N ode B ased or change the limit er type to the c ell-t o-fac e limit er. –Beginning in v ersion 17.0, the w arped-fac e gr adien t correction ( WFGC) is not supp orted with shell c on- duc tion if the abilit y to define multi-la yer shells has b een disabled thr ough the define/models/shell- conduction/multi-layer-shell text command . 17Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Known Limita tions in ANSY S Fluen t 2019 R3–For tr ansien t and time-dep enden t cases , the solution ad vances to the ne xt time st ep based on v arious inputs including time st ep siz e and c onvergenc e criteria, but it is not dir ectly dep enden t on the flo w time interval sp ecified when 'flo w-time' is selec ted f or monit oring (r eport definitions , aut osaving , transien t export and so on). For these flo w time dep enden t op erations , the ac tion will o ccur when the flo w time meets or e xceeds the sp ecified flo w time in terval. –Note the f ollowing issues aff ecting r esiduals: →Restar ting c ases tha t ha ve the High Or der Term Relaxa tion option enabled ma y pr oduce a small r e- sidual jump af ter the r estar t. (178223) →Restar ting c ases tha t ha ve turbulen t flo w with a w all-func tion-based b oundar y treatmen t and a No Slip shear c ondition a t the w all ma y pr oduce a sligh tly diff erent residual hist ory compar ed t o a c ontinu- ous r un. (165935) These issues c an o ccasionally impac t the r esidual hist ory of long tr ansien t simula tions (such as those tha t use the LES, SRS, or SBES mo del) when the solutions f or each time st ep ar e not deeply converged . –For case files cr eated in R elease 19.2 or ear lier and ar e steady, single phase , and use the pr essur e-based solv er, the Densit y explicit r elaxa tion fac tor in the Solution C ontrols task page is set t o 1 in the f ollowing circumstanc es, even though it should b e set t o 0.25 (in or der t o ma tch ho w a c ase file cr eated in R elease 2019 R1 w ould b ehave): →if the ph ysics includes r eacting flo w and/or sp ecies tr ansp ort together with the pseudo tr ansien t solution metho d, and y ou click the Default butt on in the Solution C ontrols task page →if you newly enable one or b oth of the f ollowing so tha t both ar e enabled: •a reacting flo w mo del and/or the sp ecies tr ansp ort mo del •the pseudo tr ansien t solution metho d Work-ar ound: Manually en ter 0.25 for Densit y in the Solution C ontrols task page . (182453) –The following t ext command w orks appr opriately f or setting limits t o default v alues , but fails t o tak e ac tion on solution c ontrols and AMG c ontrols: > solve/set/set-controls-to-default Set solution controls to default? [no] yes Set AMG Controls to default? [no] yes Set limits to default values? [no] yes Work-ar ound: Click the Default butt on in the Solution C ontrols task page and the Multigr id tab of the Advanc ed S olution C ontrols dialo g box, respectively. As not ed pr eviously , for older st eady- state, single-phase c ases tha t use the pr essur e-based solv er and in volve reacting flo w and/or sp ecies transp ort with the pseudo tr ansien t solution metho d, you must also manually set the Densit y ex- plicit r elaxa tion fac tor to 0.25 in the Solution C ontrols task page . (183926) •User-D efined –Any scr ipts or jour nals tha t attempt t o add menu it ems t o Fluen t pull-do wn menus (which ha ve been r e- plac ed with the F luen t ribbon) will no longer w ork.You must cr eate separ ate user-defined menus t o house all user-defined menu it ems . For additional inf ormation ab out user-defined menus , see Adding Menus t o the R ight of the R ibbon in the Fluent C ustomization Manual . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 18Introduction t o ANSY S Fluen t•User-defined func tions (UDFs) –Interpreted UDFs c annot b e used with an Infiniband in terconnec t or, when r unning in par allel, on the Cray pla tform.The c ompiled UDF appr oach must b e used inst ead. –The Visual S tudio E xpress 2015 f or Windo ws installer on Windo ws 10 installs libr aries in non-standar d locations , resulting in UDF c ompila tion failur es on this pla tform. It is r ecommended tha t you inst ead use the Visual S tudio E xpress 2015 f or D eskt op installer , or manually set the libr ary pa th based on y our local installa tion (f or e xample , LIB="C:\P rogram F iles (x86)\M icrosof t Visual S tudio 14.0\V C\lib\onec ore\amd64";%LIB%). •Graphics , Reporting , and P ostpr ocessing –Monit ors ma y continue t o pr int/plot v alues , even if the z ones on which the y are defined ar e deac tivated. –If you ar e aut osaving multiple sc enes on a Windo ws machine , the Headligh t ligh ting eff ect ma y inc on- sistently change its sta te (on/off ).This c an b e avoided b y render ing each sc ene in a separ ate gr aphics windo w. –Mean and r oot-mean-squar ed-er ror (RMSE) quan tities of cust om field func tions ar e only a vailable f or mixtures. In pr evious r eleases it w as p ossible t o sp ecify these quan tities f or phases , which w as an inc orrect behavior.This b ehavior is no longer allo wed in R16.0 or la ter releases . If you ar e running a pr e-R16.0 c ase set t o output such quan tities in R2019 R3, you ma y get a segmen tation er ror.To avoid the er ror, redefine the pr eviously defined monit ors r eporting mean or RMSE quan tities of phases . –The mouse-annota te feature is no longer a vailable . Annota tions c an still b e created using the A nnota te dialo g box (see Annota te Dialog Box in the Fluent U ser's G uide (p.3700 ) for additional inf ormation). –Beginning in v ersion 15.0, if a flux r eport for the hea t transf er rate is gener ated on the w all of a mo ving solid , the r eported v alues will include the c onvective hea t flux due t o the motion of the solid . Depending on the mesh and qualit y of the geometr y represen tation, this ma y pr esen t flux v alues tha t are diff erent than the flux sp ecified in the b oundar y condition definition (f or e xample , a non-z ero flux ma y be reported for an adiaba tic w all). –Beginning in v ersion 18.0, if you imp ort a legac y case c ontaining multiple monit ors plotting in the same windo w, you must r eview the setup t o ensur e each r eport plot is assigned t o a diff erent windo w before running the c alcula tion. If the plot windo ws are not r eassigned , then plots assigned t o the same windo w will b e lost. –It is p ossible t o use t ext commands t o create contour, vector, mesh, pathline , par ticle tr ack, XY plot , and scene gr aphics objec ts with spac es in the name (f or e xample , through the display/objects/create text command); however, objec ts with such names c annot b e displa yed using the display/ob- jects/display text command , and a ttempting t o do so will only r esult in the pr inting of an er ror. As a workaround , you c an cr eate gr aphics objec ts without spac es in the name or use the gr aphic al user in- terface to displa y gr aphics objec ts with spac es in the name . –In rare cases , the Curve Length X A xis F unc tion for X Y plots ma y not plot c orrectly, even if the cur vilinear surface is piec ewise linear and app ears t o be a single closed cur ve. A w orkaround is t o use the Direction Vector X A xis F unc tion . –Transien t sta tistics (M ean and RMS) r eported f or F luen t quan tities tha t are nonlinear func tions of the un- derlying solution v ariables r epresen t evalua tions of those quan tities using the M ean or RMS v alues of the under lying solution v ariables . For instanc e,Mean Velocity M agnitude is comput ed as the magnitude of a vector constr ucted fr om the mean v elocity comp onen ts, and Mean P ressur e Coefficien t is comput ed 19Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Known Limita tions in ANSY S Fluen t 2019 R3as the pr essur e coefficien t comput ed using the mean pr essur e.To constr uct the tr ue M ean and/or RMS values of such quan tities , you c an define a cust om field func tion and c ollec t transien t sta tistics of the cust om field func tion. For e xample , define a cust om field func tion vmag_cff = sqrt (Vx ^ 2 + Vy ^ 2 + Vz ^ 2) , and r eport Mean and RMS of vmag_cff . –Scene anima tions cr eated using Key Frames in the Anima te dialo g box are not c ompa tible with gr aphics displa ys on isosur faces (c ontours , vectors, pathlines , par ticle tr acks). Pathlines ar e not c ompa tible with scene anima tions , regar dless of the selec ted sur face(s). –When meshes c ontain a lar ge numb er of c ells (f or e xample , ~150 million c ells or higher), the meshing mode of F luen t ma y report an inc orrect numb er of sk ewed c ells, based on an inc orrect inverse or thosk ew (IOS) v alue . As a w orkaround , you c an use the (tgapi-util-set-number-of-parallel-compute- threads 1) command . (168453) –If you cr eate an X Y plot f or displa y on a r ake sur face and y ou use the sa vable X Y plot gr aphics objec t, ac- cessed b y click ing New... in the r ibbon or outline view , then the r esults ma y not b e displa yed immedia tely. If the y do not app ear, click Curves... in the XY Plot dialo g box and selec t a Symb ol from the dr op-do wn list in the Marker S tyle group b ox, click Apply , then r edispla y the X Y plot. (180547) If you ar e viewing c ell v alues ( Node Values disabled) on an X Y plot of a r ake sur face and the p oints are being sho wn as a c ontinuous line , then y ou c an change the Pattern to "empt y" in the Curves - Solution X Y Plot dialo g box (Line S tyle group b ox). (180547) –The tr ansf orm op eration in the Transf orm S urface dialo g box is not a vailable f or user-cr eated surfaces such as lines , points, iso-sur faces, and so on. To cr eate a tr ansf ormed line , point, iso-sur face, or other user-cr eated sur face, you must manually tr ansla te the input p oint(s) and cr eate a new line/p oint/iso-sur face in the r espective dialo g box (Line/R ake,Point Surface,Iso-S urface, and so on). –Densit y contour plots tha t include a solid r egion in the displa y will include the solid z one(s) in an y range calcula tions and will sho w a densit y for the solid tha t do es not r eflec t the ac tual c ase setup . Fluid z one densities ar e still displa yed c orrectly. Selec ting Densit y... and Densit y All in the Contours of drop-do wn lists will c orrectly displa y densit y values f or solids and fluids . (155346) –Special char acters (/^*%@,<>{}()?&~!=) should not b e used in objec t names: the y can aff ect ho w an objec t is render ed in the gr aphics displa y, and ma y mak e it so the objec t do es not app ear a t all. (157473) –For annota tions , the foreground and back ground color options f or text are not in sync with those specified in Preferenc es, but ar e inst ead c ontrolled using the display/set/colors/fore- ground and display/set/colors/background text commands , respectively. –For an y meshing mo de or solution mo de session tha t displa ys graphics in the gr aphics windo w (including when r unning a ba tch job with the -gu command line option) and/or sa ves pic ture files , the r ender ing / saving sp eed will b e signific antly slo wer if y ou do not f ollow all of the f ollowing b est pr actices: →Run C ortex on a suitable machine with an appr opriate gr aphics c ard and the la test dr ivers (f or details , see the ANSY S websit e). Note tha t you c an assign C ortex to a par ticular machine using the -gui_machine= command line option, or b y selec ting Specify M achine from the Graphics D ispla y M achine list in the Scheduler tab of F luen t Launcher . →Ensur e tha t Cortex / the host pr ocess is r un on a separ ate machine than tha t used f or comput e no de 0. For e xample , do not include the machine assigned using the -gui_machine option as the first machine in the hosts file / machine list (sp ecified using the -cnf=x command line option). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 20Introduction t o ANSY S Fluen t→Do not set the gr aphics dr iver to null ,x11 (for Linux), or msw (for Windo ws). →When sa ving pic ture files , enable the Fast har dcopy option in the Preferenc es dialo g box (under Graphics ). –Right-click ing p oint sur faces to displa y them fr om the Outline View tr ee is not w orking due t o a 3rd par ty issue . As a w orkaround , you c an displa y point sur faces using the Mesh D ispla y dialo g box. (181843) •Fluen t in Workbench –(For R OM) C learing the Geometr y or Mesh cells in a Fluen t fluid flo w sy stem cr eated in a pr evious release ma y pr event the R OM fr om b eing cr eated. Recreate the F luen t mesh using the la test r elease to allo w for R OM cr eation. (102336) –Coupling b etween F luen t and HFSS or Q3D Ex tractor is not supp orted. –For two-w ay coupling b etween M axwell and F luen t, by default F luen t uses the f ollowing z ones: when mapping v olumetr ic losses , the same list of z ones tha t you selec ted f or receiving v olumetr ic losses in Fluen t's Maxwell M apping Volumetr ic dialo g box are used; and when mapping sur face losses , all c ell zones ar e used .To change the z ones tha t are used f or feedback mapping , you c an use a Scheme c ommand , shown in the f ollowing e xample .This e xample sp ecifies tha t only c ell z one ID 1 and 2 ar e used:(em- set-feedback-map-cell-zone '(1 2)) . Note tha t you c an only sp ecify the IDs of the c ell z ones as the ar gumen ts. –In a F luen t analy sis sy stem, the Clear G ener ated D ata option f or the Solution cell will not clear the files asso ciated with anima tions .To ha ve the Clear G ener ated D ata option clear the anima tion files as w ell, you must define the FLUENT_WB_REMOVE ALL_GENERATE_FILES as a sy stem en vironmen t variable on y our lo cal machine , prior t o op ening Workbench. •Fluen t as a S erver –When r unning F luen t with the -aaS option, if you ha ve a mesh with a v ery low cell c oun t and ha ve set a lar ge numb er of it erations t o be stored using the Residual M onit ors dialo g box (see Storing R esidual Hist ory Points in the Fluent U ser's G uide (p.2650 )), you will see a r elative degr adation of p erformanc e. Reducing the numb er of st ored it erations will r educ e this degr adation. –When launching F luen t with the -gu or -g command line options and F luen t as a ser ver enabled , Fluen t will r un with the gr aphic user in terface minimiz ed. •Third-par ty sof tware –Fluen t-Platform LSF in tegration is not supp orted on the MS Windo ws pla tform. –Fluen t-SGE in tegration is supp orted only on Linux pla tforms. –Wave and GT-PO WER c oupling ar e available only with stand-alone ANSY S Fluen t and not in the Workbench environmen t. –Supp orted v ersions of thir d-par ty sof tware are list ed b elow: Table 1.1: Supp orted Versions of Third-Party Software Supp orted Version Third-Party Software 6.14 ODB Libr ary: 6.14.5 Abaqus 21Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Known Limita tions in ANSY S Fluen t 2019 R3Supp orted Version Third-Party Software 5.1 Altair HYPERMESH 5.0 AVS 3.2.1 CGNS 7.0* Cray MPI (MPT ) 4.2 Data Explor er Ensigh t 6 EnSight 6 ( TUI only) 10.1.6 EnSight Case G old 1.3 FAST 16.0 Fieldview v2018 B uild 3 GT-PO WER 23.00-1 HOOPS 9.1.4.5 ( Windo ws) and 9.1.4.3 (Linux) HP/IBM MPI I-deas NX S eries 11 I-deas 2018.3.210** Intel MPI 1.6.18 libpng 970.0 LSTC-DYNA 9.0.1 Microsof t MPI 3.0.5 MPC CI Bulk da ta input file - MSC.NASTR AN 2010 NASTR AN OUTPUT2 da ta file - NX/NASTR AN 10 9.1 NIST 3.1.2*** Open MPI 3.0 PATRAN PTC/M echanic a Wildfir e 4.0 PTC MECHANIC A 2.5.0 Sundials Tecplot file f ormat, version 11.2 TECPL OT 4.3.6 VKI 2019.1 WAVE 1.2.8 zlib * When using MPT v ersion 5.0 and higher (up t o, but not including 7.0), you must set the f ollowing environmen t variable:export FLUENT_USE_CRAY_MPT5=1 . ** B y default , the In tel MPI ma y fail when mixing har dware for c omput e no des. As a w orkaround , you c an use the f ollowing en vironmen t setting: I_MPI_PLATFORM zero *** This v ersion of Op en MPI is dep enden t on the f ollowing v ersions (or higher) of sof tware: →OFED v ersion 3.5 →LSF v ersion 10.1 →UGE v ersion 8.5 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 22Introduction t o ANSY S Fluen t→PBS v ersion 13.1.2 •Other –If the net work connec tion is lost dur ing a ser ial or par allel c alcula tion, the F luen t session ma y termina te abnor mally . –The IRIS Image and HPGL har d copy formats ar e no longer supp orted in ANSY S Fluen t. –When using ANSY S Fluen t with the R emot e Solve Manager (RSM): →Only one c opy of a sa ved pr ojec t tha t is in the p ending sta te can r econnec t succ essfully . →Maxwell c oupling is not supp orted. →UDFs ar e supp orted with limita tions as detailed in Submitting F luen t Jobs t o Remot e Solve Manager in Workbench U ser's G uide . –The turb o-averaged c ontour plot in turb omachiner y postpr ocessing ma y giv e an une xpected c ontour region in a selec ted t opology. –The Inverse D istanc e and Least S quar es profile in terpolation metho ds ar e not applic able when a pr ofile is attached t o cell z ones . –Heat exchanger net works ar e not supp orted in HDF-f ormatted c ase and da ta files . –When op ening ANSY S Help fr om F luen t in Linux, you ma y receive an er ror message in the Linux c onsole . This c an r esult when another user has cr eated the installa tion and r un F luen t, thus cr eating a r egistr y file; if you then r un this same installa tion, ther e will b e a p ermissions c onflic t. As a w orkaround , remo ve the registr y file: path/ansys_inc/v195/Tools/mono/Linux64/etc/mono/registry (wher e path is the dir ectory in which y ou ha ve plac ed the r elease dir ectory).Then change the permissions f or the M ono pla tform in or der t o remo ve wr ite acc ess fr om the dir ectory: path/ansys_inc/v195/Tools/mono/Linux64/etc/mono –On Windo ws, mesh r eading in to a ser ial ANSY S Fluen t session ma y fail if y ou use mor e than 20 million cells p er core. –For non-c onformal in terfaces, the use of the Matching option with the Mapp ed option is not r ecommen- ded , esp ecially if the e xtents of Interface Zone 1 and Interface Zone 2 do not c oincide . –Fluen t do es not supp ort non-ASCII char acters in the names of files , zones , and b oundar ies. –When e xiting a F luen t session on Linux tha t was star ted with the L oad A CT option, Fluen t ma y become unresponsiv e. If this o ccurs , the F luen t process must b e manually t ermina ted. In the c onsole , the er ror message sp ecifies tha t a c orrupted double-link ed list is r esponsible f or the er ror. Because this une xpected shut down o ccurs af ter the pr ojec t has b een sa ved, no da ta is lost. –When F luen t is r un on Linux with the L oad A CT option, Fluen t ma y repeatedly issue the f ollowing w arning during solution it eration: Unexpected error checking licensing server. 23Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Known Limita tions in ANSY S Fluen t 2019 R3This w arning is har mless and do es not impac t Fluen t or A CT usage . –When r unning a stand-alone instanc e of F luen t in a mix ed Windo ws / Linux c onfigur ation or fr om a r emot e Windo ws installa tion, ACT do es not op en.To correct the pr oblem, you must set the AWP_ROOT195 en- vironmen t variable t o point to the ANSY S installa tion dir ectory. –ACT with ANSY S Fluen t is disabled on Linux sy stems star ting in R elease 19.2. To use A CT with ANSY S Fluen t, use R elease 19.2 or la ter on Windo ws or use R elease 19.1 on Linux. (177173) –If you set the numb er of meshing pr ocesses t o 0 (with the goal of r everting t o a v ersion of F luen t tha t is similar t o ser ial fr om R18.1), your r equest will b e ignor ed if y ou ha ve sp ecified a nonz ero value f or the numb er of solv er pr ocesses . In such cir cumstanc es, the numb er of solv er pr ocesses will b e used f or launching b oth meshing and solv er mo des. –If the net work connec tion is lost dur ing a ser ial or par allel c alcula tion, the ANSY S Fluen t session ma y ter- mina te abnor mally . –ANSY S Fluen t uses se veral TCP/IP p orts for communic ations and er ror handling . Port conflic ts with other programs tr ying t o use the same p orts ar e handled b y ANSY S Fluen t and gener ate warnings similar t o the f ollowing 428: mpt_accept: warning: incorrect exercise message "GET /" from 10.1.0.188 on port 56564 Long r unning lar ge sessions ar e mor e pr one t o gener ating such w arnings , but these ar e gener ally save for y ou t o ignor e. •Remot e Visualiza tion C lient –On some Linux machines y ou ma y see a w arning message c ontaining SO_REUSEPORT printed in the console when star ting the ser ver.This message c an b e ignor ed—it will not ha ve an y eff ect on the simula tion or on the R emot e Visualiza tion C lient. (176526) –For a clien t session with multiple c onnec ted ser vers, only one ser ver can r eceive commands thr ough the Send C ommand t o Server dialo g box—tha t ser ver is whiche ver one y ou send a c ommand t o first using this dialo g box. As a w orkaround , you c an use the P ython c onsole t o control the other c onnec ted ser vers. (177632) •Fluen t Meshing –Limita tions r elated t o the F luen t guided meshing w orkflows are do cumen ted separ ately. See Limita tions of the F luen t Guided Workflows (p.124) for details . –After ANSY S Fluen t 19.2, you c an no longer ha ve multiple in terior z ones defined in a single c ell z one . If your c ase file has such z ones , the y will not app ear as a vailable z ones .Workaround: Read the mesh file into ANSY S Fluen t 19.2, and set the t ype for the in terior z ones t o be 'w all' in or der t o restore the missing zones . (143347) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 24Introduction t o ANSY S Fluen tChapt er 2: Basic S teps f or CFD A naly sis using ANSY S Fluen t Before you b egin y our CFD analy sis using ANSY S Fluen t, careful c onsider ation of the f ollowing issues will c ontribut e signific antly t o the succ ess of y our mo deling eff ort. Also, when y ou ar e planning a CFD projec t, be sur e to tak e ad vantage of the cust omer supp ort available t o all ANSY S Fluen t users . For mor e inf ormation, see the f ollowing sec tions: 2.1. Steps in S olving Your CFD P roblem 2.2. Planning Your CFD A naly sis 2.1. Steps in S olving Your CFD P roblem Onc e you ha ve det ermined the imp ortant features of the pr oblem y ou w ant to solv e, follow the basic procedur al st eps sho wn b elow. 1.Define the mo deling goals . 2.Create the mo del geometr y and mesh. 3.Set up the solv er and ph ysical mo dels . 4.Comput e and monit or the solution. 5.Examine and sa ve the r esults . 6.Consider r evisions t o the numer ical or ph ysical mo del par amet ers, if nec essar y. Step 2. of the solution pr ocess r equir es a geometr y mo deler and mesh gener ator.You c an use D esign- Modeler and ANSY S M eshing within ANSY S Workbench or y ou c an use a separ ate CAD sy stem f or geometr y mo deling and mesh gener ation. When meshing 3D geometr ies, you c an also use the meshing mode of F luen t. Alternatively, you c an use supp orted C AD pack ages t o gener ate volume meshes f or imp ort into ANSY S Fluen t (see the User's G uide (p.1)). For mor e inf ormation on cr eating geometr y and gener ating meshes using each of these pr ograms , refer to their r espective manuals . The details of the r emaining st eps ar e covered in the User's G uide (p.1). 2.2. Planning Your CFD A naly sis For each of the pr oblem-solving st eps, ther e ar e some questions tha t you need t o consider : •Defining the M odeling G oals –What results ar e you lo oking f or, and ho w will the y be used? →What are your mo deling options? →What ph ysical mo dels will need t o be included in y our analy sis? 25Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.→What simplifying assumptions do y ou ha ve to mak e? →What simplifying assumptions c an y ou mak e? →Do you r equir e a unique mo deling c apabilit y? •Could y ou use user-defined func tions (wr itten in C)? –What degr ee of accur acy is r equir ed? –How quick ly do y ou need the r esults? –How will y ou isola te a piec e of the c omplet e ph ysical sy stem? –Where will the c omputa tional domain b egin and end? →Do you ha ve boundar y condition inf ormation a t these b oundar ies? →Can the b oundar y condition t ypes acc ommo date tha t inf ormation? →Can y ou e xtend the domain t o a p oint wher e reasonable da ta exists? –Can it b e simplified or appr oxima ted as a 2D or axisymmetr ic pr oblem? •Creating Your M odel G eometr y and M esh ANSY S Fluen t uses unstr uctured meshes in or der t o reduc e the amoun t of time y ou sp end gener ating meshes , to simplify the geometr y mo deling and mesh gener ation pr ocess, to enable mo deling of mor e comple x geometr ies than y ou c an handle with c onventional, multi-blo ck str uctured meshes , and t o enable y ou t o adapt the mesh t o resolv e the flo w-field f eatures. ANSY S Fluen t can also use body-fitt ed, blo ck-str uctured meshes (f or e xample , those used b y ANSY S Fluen t 4 and man y other CFD solv ers). ANSY S Fluen t is c apable of handling tr iangular and quadr ilateral elemen ts (or a c ombin- ation of the t wo) in 2D , and t etrahedr al, hexahedr al, pyramid , wedge , and p olyhedr al elemen ts (or a combina tion of these) in 3D .This fle xibilit y enables y ou t o pick mesh t opologies tha t are best suit ed for y our par ticular applic ation, as descr ibed in the User's G uide (p.1). For 3D geometr ies, you c an cr eate the mesh using the meshing mo de of F luen t; other wise , you must gener ate the initial mesh (wha tever the elemen t types used) outside of F luen t or use one of the C AD systems f or which mesh imp ort filt ers e xist. When in solution mo de, Fluen t can b e used t o adapt all types of meshes (e xcept f or p olyhedr al), in or der t o resolv e lar ge gr adien ts in the flo w field . The f ollowing questions should b e consider ed when y ou ar e gener ating a mesh: –Can y ou b enefit fr om other ANSY S, Inc. produc ts such as CFX or ANSY S Icepak? –Can y ou use a quad/he x mesh or should y ou use a tr i/tet mesh or a h ybrid mesh? →How comple x is the geometr y and flo w? →Will you need a non-c onformal in terface? –What degr ee of mesh r esolution is r equir ed in each r egion of the domain? →Is the r esolution sufficien t for the geometr y? Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 26Basic S teps f or CFD A naly sis using ANSY S Fluen t→Can y ou pr edic t regions with high gr adien ts? →Will you use adaption t o add r esolution? –Do you ha ve sufficien t comput er memor y? →How man y cells ar e requir ed? →How man y mo dels will b e used? •Setting U p the S olver and P hysical M odels For a giv en pr oblem, you will need t o: –Imp ort and check the mesh. –Selec t the numer ical solv er (f or e xample , densit y based , pressur e based , unst eady, and so on). –Selec t appr opriate ph ysical mo dels . →Turbulenc e, combustion, multiphase , and so on. –Define ma terial pr operties. →Fluid →Solid →Mixture –Prescr ibe op erating c onditions . –Prescr ibe boundar y conditions a t all b oundar y zones . –Provide an initial solution. –Set up solv er controls. –Set up c onvergenc e monit ors. –Initializ e the flo w field . •Computing and M onit oring Your S olution –The discr etized c onser vation equa tions ar e solv ed it eratively. →A numb er of it erations ar e usually r equir ed t o reach a c onverged solution. –Convergenc e is r eached when: →Changes in solution v ariables fr om one it eration t o the ne xt are negligible . •Residuals pr ovide a mechanism t o help monit or this tr end . →Overall pr operty conser vation is achie ved. 27Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Planning Your CFD A naly sis–The accur acy of a c onverged solution is dep enden t up on: →Appropriateness and accur acy of ph ysical mo dels . →Mesh r esolution and indep endenc e. →Problem setup . •Examining and S aving Your Results Examine the r esults t o review the solution and e xtract useful da ta. –Visualiza tion t ools c an b e used t o answ er such questions as: →What is the o verall flo w pa ttern? →Is ther e separ ation? →Where do sho cks, shear la yers, and so on f orm? →Are key flo w features b eing r esolv ed? –Numer ical reporting t ools c an b e used t o calcula te the f ollowing quan titative results: →Forces and momen ts →Average hea t transf er coefficien ts →Surface and v olume in tegrated quan tities →Flux balanc es •Revising Your M odel Onc e your solution is c onverged , the f ollowing questions should b e consider ed when y ou ar e analyzing the solution: –Are ph ysical mo dels appr opriate? →Is flo w turbulen t? →Is flo w unst eady? →Are ther e compr essibilit y eff ects? →Are ther e 3D eff ects? –Are boundar y conditions c orrect? →Is the c omputa tional domain lar ge enough? →Are boundar y conditions appr opriate? →Are boundar y values r easonable? Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 28Basic S teps f or CFD A naly sis using ANSY S Fluen t–Is the mesh adequa te? →Can the mesh b e adapt ed t o impr ove results? →Does the solution change signific antly with adaption, or is the solution mesh indep enden t? →Does b oundar y resolution need t o be impr oved? 29Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Planning Your CFD A naly sisRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 30Chapt er 3: Guide t o a S uccessful S imula tion U sing ANSY S Fluen t The f ollowing guidelines c an help y ou mak e sur e your CFD simula tion is a succ ess. Before lo gging a technic al supp ort request , mak e sur e you do the f ollowing: 1.Examine the qualit y of the mesh in F luen t. There ar e two basic things tha t you should do b efore you star t a simula tion: •Perform a mesh check t o avoid pr oblems due t o inc orrect mesh c onnec tivit y, and so on. In par ticular , you should b e sur e tha t the minimum r eported c ell v olume is not nega tive. •Look a t maximum c ell sk ewness (f or e xample , using the Comput e butt on in the Contours dialo g box after initializing the mo del). As a r ule of thumb , the sk ewness should b e below 0.98. You c an also use the Rep ort Qualit y func tion t o calcula te the minimum c ell or thogonalit y.You c an find mor e details about mesh qualit y consider ations in Mesh Q ualit y in the Fluent U ser's G uide (p.719). If ther e ar e mesh pr oblems , you ma y ha ve to re-mesh the pr oblem. 2.Scale the mesh and check length units . In ANSY S Fluen t, all ph ysical dimensions ar e initially assumed t o be in met ers.You should sc ale the mesh acc ordingly . Other quan tities c an also b e sc aled indep enden tly of other units used . ANSY S Fluen t defaults t o SI units . 3.Emplo y the appr opriate ph ysical mo dels . 4.Set the ener gy under-r elaxa tion fac tor b etween 0.95 and 1. For pr oblems with c onjuga te hea t transf er, when the c onduc tivit y ratio is v ery high, smaller v alues of the ener gy under-r elaxa tion fac tor pr actically stall the c onvergenc e rate. 5.Use no de-based gr adien ts with unstr uctured t etrahedr al meshes . The no de-based a veraging scheme is k nown t o be mor e accur ate than the default c ell-based scheme for unstr uctured meshes , most notably f or tr iangular and t etrahedr al meshes . 6.Monit or convergenc e with r esiduals hist ory. Residual plots c an sho w when the r esidual v alues ha ve reached the sp ecified t oler ance. After the simula tion, not e if y our r esiduals ha ve decr eased b y at least 3 or ders of magnitude t o at least . For the pr essur e-based solv er, the sc aled ener gy residual must decr ease t o . Also, the sc aled species r esidual ma y need t o decr ease t o to achie ve sp ecies balanc e. You c an also monit or lif t, drag, or momen t forces as w ell as p ertinen t variables or func tions (f or example , sur face in tegrals) a t a b oundar y or an y defined sur face. 7.Run the CFD simula tion using sec ond or der discr etiza tion f or b etter accur acy rather than a fast er solution. 31Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.A converged solution is not nec essar ily a c orrect one .You should use the sec ond-or der up wind discr etiza tion scheme f or final r esults . 8.Monit or v alues of solution v ariables t o mak e sur e tha t an y changes in the solution v ariables fr om one it er- ation t o the ne xt are negligible . 9.Verify tha t property conser vation is sa tisfied . After the simula tion, not e if o verall pr operty conser vation has b een achie ved. In addition t o monit- oring r esidual and v ariable hist ories, you should also check f or o verall hea t and mass balanc es. At a minimum, the net imbalanc e should b e less than 1% of the smallest flux thr ough the domain boundar y. 10.Check f or mesh dep endenc e. You should ensur e tha t the solution is mesh-indep enden t and use mesh adaption t o mo dify the mesh or cr eate additional meshes f or the mesh-indep endenc e stud y. 11.Check t o see tha t the solution mak es sense based on engineer ing judgmen t. If flo w features do not seem r easonable , you should r econsider y our ph ysical mo dels and b oundar y conditions . Reconsider the choic e of the b oundar y locations (or the domain). An inadequa te choic e of domain (esp ecially the outlet b oundar y) can signific antly impac t solution accur acy. You ar e enc ouraged t o collab orate with y our t echnic al supp ort engineer in or der t o de velop a solution process tha t ensur es go od results f or y our sp ecific applic ation. This t ype of c ollab oration is a go od in- vestmen t of time f or b oth y ourself and the ANSY S Fluen t supp ort engineer . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 32Guide t o a Succ essful S imula tion U sing ANSY S Fluen tChapt er 4: Starting and E xecuting ANSY S Fluen t This chapt er pr ovides instr uctions f or star ting and e xecuting ANSY S Fluen t. 4.1. Starting ANSY S Fluen t 4.2. Running ANSY S Fluen t in B atch M ode 4.3. Switching B etween M eshing and S olution M odes 4.4. Check pointing an ANSY S Fluen t Simula tion 4.5. Cleaning U p Processes F rom an ANSY S Fluen t Simula tion 4.6. Exiting ANSY S Fluen t 4.1. Starting ANSY S Fluen t The f ollowing sec tions descr ibe ho w star t ANSY S Fluen t: 4.1.1. Starting ANSY S Fluen t Using F luen t Launcher 4.1.2. Starting ANSY S Fluen t on a Windo ws System 4.1.3. Starting ANSY S Fluen t on a Linux S ystem 4.1.4. Command Line S tartup Options 4.1.1. Starting ANSY S Fluen t Using F luen t Launcher You c an in teractively sp ecify ANSY S Fluen t dimension, displa y, processing and other options using the Fluen t Launcher . 33Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.To star t the F luen t Launcher , do one of the f ollowing: •Start ANSY S Fluen t from the Linux or Windo ws command line with no ar gumen ts. •Start ANSY S Fluen t from the Windo ws Start menu . •Start ANSY S Fluen t from the Windo ws deskt op or Q uick Launch bar . Any options set in the F luen t Launcher will b e retained f or y our ne xt session. Specify the Dimension of the simula tion y ou in tend t o perform. Imp ortant For Meshing M ode, you must selec t 3D.Meshing M ode is not a vailable if 2D is selec ted. Selec t your r equir ed Displa y Options . •Optionally , cho ose t o Displa y M esh A fter Reading (disabled b y default). This option is applic able only t o volume meshes and not sur face meshes . All of the b oundar y zones will b e displa yed e xcept f or the in terior zones of 3D geometr ies. Note You c an o verride this option on a file-b y-file basis using the Displa y M esh A fter Reading option in the Selec t File dialo g box tha t op ens when y ou ar e reading in a file . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 34Starting and Ex ecuting ANSY S Fluen tOptionally , enable the Load A CT option t o load ANSY S ACT. For additional inf ormation on A CT, see Customizing F luen t in the Fluent U ser's G uide (p.3233 ). Selec t your r equir ed Options . •Choose t o perform solution c alcula tions in Double-P recision mo de, if desir ed. (Default is single-pr ecision mode) S ee Single-P recision and D ouble-P recision S olvers (p.38) to help with y our decision. Note Meshing M ode is alw ays run in Double P recision .This option applies f or S olution M ode only . •Choose t o star t ANSY S Fluen t in Meshing M ode, if desir ed. (Default is S olution M ode.) See the Fluen t User’s Guide (p.1) for fur ther details ab out using F luen t in meshing mo de. •Choose an appr opriate Use J ob Scheduler option, if applic able . For e xample , the M icrosof t Job Scheduler for Windo ws, or LSF , SGE , and PBS P ro on Linux. For mor e inf ormation ab out using F luen t Launcher with job schedulers , see Setting Scheduler Options in F luen t Launcher (p.42), as w ell as Setting P arallel Scheduler Options in F luen t Launcher (p.3051 ) in the User's G uide (p.1). Note This option is a vailable only if Parallel is selec ted under Processing Options . •You c an cho ose t o run par allel simula tions on Linux clust ers, via the Windo ws interface using the Use Remot e Linux N odes option (see Setting R emot e Options in F luen t Launcher (p.41) for details). Note This option is a vailable only if Parallel is selec ted under Processing Options . Selec t your r equir ed Processing Options . •Use Serial to restrict the meshing/solution c alcula tions t o a single pr ocessor c ore. •Use Parallel to allo w multiple simultaneous pr ocesses .You will b e ask ed t o sp ecify the numb er of processes f or b oth M eshing (if enabled) and S olver. See Setting P arallel Options in F luen t Launch- er (p.39).When par allel is enabled , several additional par allel-sp ecific it ems ar e available f or selec tion in the Parallel ribbon tab . Selec t Show M ore Options to expand the F luen t Launcher windo w to reveal mor e options . (Fig- ure 4.1: The G ener al Options Tab of F luen t Launcher (p.37)). Note tha t onc e Fluen t Launcher e xpands , 35Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Starting ANSY S Fluen tthe Show M ore Options butt on b ecomes the Show F ewer Options butt on, allo wing y ou t o hide the additional options . Imp ortant Fluen t Launcher also app ears when y ou star t ANSY S Fluen t within ANSY S Workbench. For mor e inf ormation, see the separ ate ANSY S Fluen t in Workbench U ser's G uide . 4.1.1.1. Setting G ener al O ptions in F luent L auncher Set file and pa th options using the Gener al Options tab in F luen t Launcher . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 36Starting and Ex ecuting ANSY S Fluen tFigur e 4.1: The G ener al Options Tab of F luen t Launcher 1. Enable Pre/Post Only to run ANSY S Fluen t with only the setup and p ostpr ocessing c apabilities a vailable . The default ANSY S Fluen t full solution mo de allo ws you t o set up , solv e, and p ostpr ocess a pr oblem, while Pre/Post Only will not allo w you t o perform calcula tions . 37Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Starting ANSY S Fluen t2. Specify the pa th of y our cur rent working dir ectory using the Working D irectory field or click to browse thr ough y our dir ectory str ucture. Note a Uniform N aming C onvention (UNC) pa th c annot b e set as a w orking dir ectory.You need t o map a dr ive to the UNC pa th (Windo ws only) 3. Specify the lo cation of the ANSY S Fluen t installa tion on y our sy stem using the Fluen t Ro ot P ath field , or click to br owse thr ough y our dir ectory str ucture.Try to use the UNC pa th if applic able . Note The butt on aut oma tically c onverts a lo cal pa th to a UNC pa th if an y ma tching shar ed dir ectory is f ound ( Windo ws only). Onc e set , various fields in F luen t Launcher (f or example , par allel settings , etc.) ar e aut oma tically p opula ted with the a vailable options , dep ending on the ANSY S Fluen t installa tions tha t are available . 4. To use a jour nal file t o aut oma tically load the c ase, compile an y user-defined func tions , iterate un til the solution c onverges, and wr ite results t o an output file , a. Enable Use J our nal F ile. Note This option do es not supp ort reading multiple jour nal files . b.Specify y our jour nal file pa th and name , or click to br owse thr ough y our dir ectory str ucture to locate the file . 4.1.1.2. Single-P recision and D ouble-P recision S olvers Both single-pr ecision and double-pr ecision v ersions of ANSY S Fluen t are available on all c omput er platforms. For most c ases , the single-pr ecision solv er will b e sufficien tly accur ate, but c ertain t ypes of pr oblems ma y benefit fr om the use of a double-pr ecision v ersion. Several examples ar e list ed b elow: •If your geometr y has f eatures of v ery dispar ate length sc ales (f or e xample , a very long , thin pip e), single- precision c alcula tions ma y not b e adequa te. Note tha t no dal c oordina tes ar e alw ays stored in double precision (e ven for the single-pr ecision v ersion of ANSY S Fluen t), so the y are not a c oncern in this r egar d. •If your geometr y involves multiple enclosur es c onnec ted via small-diamet er pip es (f or e xample , aut omotiv e manif olds), mean pr essur e levels in all but one of the z ones c an b e quit e lar ge (sinc e you c an set only one global r eference pr essur e location). Double-pr ecision c alcula tions ma y ther efore be nec essar y to resolv e the pr essur e diff erences tha t drive the flo w, sinc e these will t ypic ally b e much smaller than the pr essur e levels. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 38Starting and Ex ecuting ANSY S Fluen t•For conjuga te pr oblems in volving high ther mal-c onduc tivit y ratios and/or high-asp ect-ratio meshes , convergenc e and/or accur acy ma y be impair ed with the single-pr ecision solv er, due t o inefficien t transf er of b oundar y inf ormation. •For multiphase pr oblems wher e the p opula tion balanc e mo del is used t o resolv e par ticle siz e distr ibutions , which c ould ha ve sta tistic al momen ts whose v alues span man y or ders of magnitude . Note ANSY S Fluen t allo ws only a p eriod to be used as a decimal separ ator. If your sy stem is set to a E uropean lo cale tha t uses a c omma separ ator (f or e xample , German y), fields tha t acc ept numer ic input ma y acc ept a c omma, but ma y ignor e everything af ter the c omma. If your system is set t o a non-E uropean lo cale, numer ic fields will not acc ept a c omma a t all. ANSY S Workbench acc epts c ommas as decimal delimit ers.These ar e transla ted in to periods when da ta is passed t o ANSY S Fluen t. 4.1.1.3. Setting P arallel O ptions in F luent L auncher The Parallel S ettings tab allo ws you t o sp ecify settings f or running ANSY S Fluen t in par allel. This tab is only a vailable if y ou ha ve selec ted Parallel under Processing Options . 39Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Starting ANSY S Fluen tFigur e 4.2: The P arallel S ettings Tab of F luen t Launcher Onc e you selec t Parallel , 1. Enter the numb er of pr ocesses t o be used f or meshing under Meshing P rocesses , if enabled . 2. Enter the numb er of pr ocesses t o be used f or solution under Solver P rocesses .When y ou change t o solution mo de, additional pr ocesses will b e spa wned as nec essar y to br ing the t otal numb er of pr ocesses to this v alue .This must b e set t o a v alue gr eater than or equal t o Meshing P rocesses . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 40Starting and Ex ecuting ANSY S Fluen t3. If your machine is equipp ed with G ener al Purpose G raphics P rocessing U nits y ou c an also sp ecify GPGPU s per M achine . Note With P arallel pr ocessing enabled , some global file r ead and wr ite op erations ar e aff ected. Unavailable options will ha ve their menu en try gr ayed out. Refer to Parallel P rocessing in the Fluent U ser's G uide (p.3045 ) for details on par allel pr ocessing using Fluen t and Starting P arallel ANSY S Fluen t Using F luen t Launcher in the Fluent U ser's G uide (p.3047 ) for additional details par allel pr ocess c onfigur ation options on this tab . 4.1.1.4. Setting R emot e O ptions in F luent L auncher The Remot e tab ( Figur e 4.3: The R emot e Tab of F luen t Launcher (p.42)) allo ws you t o sp ecify settings for running ANSY S Fluen t par allel simula tions on Linux clust ers, via the Windo ws interface. 41Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Starting ANSY S Fluen tFigur e 4.3: The Remot e Tab of F luen t Launcher For additional inf ormation ab out this tab , see Setting A dditional Options When R unning on R emot e Linux M achines (p.3054 ) in the User's G uide (p.1). 4.1.1.5. Setting Scheduler O ptions in F luent L auncher The Scheduler tab ( Figur e 4.4: The Scheduler Tab of F luen t Launcher ( Windo ws 64 Version) (p.43)) allows you t o sp ecify settings f or running ANSY S Fluen t with v arious job schedulers (f or e xample , the Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 42Starting and Ex ecuting ANSY S Fluen tMicrosof t Job Scheduler f or Windo ws, or LSF , SGE , and PBS P ro on Linux). This tab is a vailable if y ou have selec ted Use J ob Scheduler under Options . Figur e 4.4: The Scheduler Tab of F luen t Launcher ( Windo ws 64 Version) For additional inf ormation ab out this tab , see Setting P arallel Scheduler Options in F luen t Launch- er (p.3051 ) in the User's G uide (p.1). 43Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Starting ANSY S Fluen t4.1.1.6. Setting E nvironment O ptions in F luent L auncher The Environmen t tab ( Figur e 4.5: The En vironmen t Tab of F luen t Launcher (p.44)) allo ws you t o specify c ompiler settings f or c ompiling user-defined func tions (UDFs) with ANSY S Fluen t (Windo ws only). The Environmen t tab also allo ws you t o sp ecify en vironmen t variable settings f or running ANSY S Fluen t. Figur e 4.5: The E nvironmen t Tab of F luen t Launcher Specify a ba tch file tha t contains UDF c ompila tion en vironmen t settings b y selec ting the Set up Compila tion E nvironmen t for UDF check b ox (enabled b y default). Onc e selec ted, you c an then Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 44Starting and Ex ecuting ANSY S Fluen tenter a ba tch file name in the t ext field . By default , Fluen t Launcher uses the udf.bat file tha t is located in the dir ectory wher e ANSY S Fluen t is installed . It is r ecommended tha t you k eep the default batch file , which is t ested with the thr ee most r ecent versions of MS Visual S tudio C++ c ompilers a t the time of the ANSY S Fluen t release da te (as not ed in Compiler R equir emen ts for Windo ws Systems ). For mor e inf ormation ab out c ompiling UDFs , see the separ ate Fluen t Customiza tion M anual . Under Other E nvironmen t Variables , enter or edit lic ense file or en vironmen t variable inf ormation in the t ext field . For e xample ,FLUENT_AFFINITY=x specifies the pr ocess binding (affinit y) setting , in the same manner as the -affinity=x command line option (see Parallel Options (p.51) for details). Using the Default butt on r esets the default v alue(s). 4.1.2. Starting ANSY S Fluen t on a Windo ws System There ar e two ways to star t ANSY S Fluen t on a Windo ws system: •From the Windo ws Start menu , click Start > ANSY S 2019 R3 > F luid D ynamics > F luen t 2019 R3 This option star ts Fluen t Launcher (see Starting ANSY S Fluen t Using F luen t Launcher (p.33)).The Fluen t Launcher ma y also b e acc essed via an ic on on y our deskt op or in the Q uick Launch bar . Note If the default “ANSY S 2019 R3” program gr oup name w as changed when ANSY S Fluen t was installed , you will find the Fluen t menu it em in the pr ogram gr oup with the new name that was assigned , rather than in the ANSY S 2019 R3 program gr oup . •From a C ommand P rompt windo w, type fluent version , wher e version is replac ed with one of the four options sp ecifying the dimension and pr ecision of the solv er. –2d for the 2D , single-pr ecision solv er. –3d for the 3D , single-pr ecision solv er. –2ddp for the 2D , double-pr ecision solv er. –3ddp for the 3D double-pr ecision solv er. For additional inf ormation on star ting F luent fr om the c ommand pr ompt , see Command Line Star tup Options (p.47). Imp ortant To be able t o star t ANSY S Fluen t from the c ommand pr ompt , be sur e the pa th to your ANSY S Fluen t home dir ectory is in y our c ommand sear ch pa th en vironmen t variable b y 45Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Starting ANSY S Fluen texecuting the setenv.exe program lo cated in the ANSY S Fluen t dir ectory (for e xample , C:\Program Files\ANSYS Inc\v195\fluent\ntbin\win64 ). Tip You c an also star t the par allel v ersion of ANSY S Fluen t, or star t ANSY S Fluen t in meshing mode fr om the C ommand P rompt. •To star t the par allel v ersion on x processors , type fluent version -tx , replacing version with the desir ed solv er version and x with the numb er of pr ocessors . For e xample ,fluent 3d -t4 to run the 3D v ersion on 4 pr ocessors . •To star t in meshing mo de, add the c ommand line option -meshing . For e xample ,fluent 3d -meshing to star t in meshing mo de. •Both par allel and meshing mo de ma y be combined .You must sp ecify the numb er of meshing processes using -tmy . For e xample ,fluent 3ddp -meshing -tm4 -t8 will star t ANSY S Fluen t in meshing mo de with 4 meshing pr ocesses .When swit ched t o solution mo de, the solv er will b e 3D , double pr ecision and r un 8 pr ocesses . 4.1.3. Starting ANSY S Fluen t on a Linux S ystem There ar e two ways to star t ANSY S Fluen t on a Linux sy stem: •Start Fluen t from the c ommand line without sp ecifying a v ersion, and then use F luen t Launcher t o cho ose the appr opriate version along with other options . See Starting ANSY S Fluen t Using F luen t Launcher (p.33) for details . •Start the appr opriate version fr om the c ommand line b y typing fluent version , wher e version is replac ed with one of the f our options sp ecifying the dimension and pr ecision of the solv er. –2d for the 2D , single-pr ecision solv er. –3d for the 3D , single-pr ecision solv er. –2ddp for the 2D , double-pr ecision solv er. –3ddp for the 3D double-pr ecision solv er. You c an also star t the par allel v ersion of ANSY S Fluen t from the c ommand line .To star t the par allel version on x processors , type fluent version -tx at the pr ompt , replacing version with the desir ed solv er v ersion and x with the numb er of pr ocessors . For e xample ,fluent 3d -t4 will r un the 3D v ersion on 4 pr ocessors . See Starting P arallel ANSY S Fluen t on a Linux S ystem (p.3063 ) in the User's G uide (p.1) for mor e inf ormation ab out star ting the par allel solv ers. Note ANSY S Fluen t aut oma tically selec ts the b est gr aphics dr iver and defaults t o the X11 dr iver when it do es not det ect the r equir ed gr aphics supp ort.You c an use the HOOPS_PICTURE Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 46Starting and Ex ecuting ANSY S Fluen tenvironmen t variable t o force a par ticular gr aphics dr iver, if y ou f eel it is nec essar y to use an alt ernate dr iver. 4.1.4. Command Line S tartup Options Table 4.1: Available C ommand Line Options f or Linux and Windo ws Platforms (p.47) lists the a vailable command line ar gumen ts for Linux and Windo ws. More detailed descr iptions of these options c an b e found in the f ollowing sec tions . To obtain inf ormation ab out a vailable star tup options , you c an t ype fluent -help before star ting up F luen t. Table 4.1: Available C ommand Line Options f or Linux and Windo ws Platforms Descr iption Platform Option Start Fluen t in ser ver mo de. all -aas Load A CT on F luen t star tup. all -act Specifies the pr ocess binding (affinit y) setting , as descr ibed in Parallel Options (p.51).all -affinity= Loads the sp ecified applic ation, for example flremote launches the Remot e Visualiza tion C lient.all -app= Runs the sp ecified scr ipt in the specified applic ation (must b e used with the -app= star tup option.all -appscript= Uses the M icrosof t Job Scheduler , wher e is the head no de name .Windo ws only -ccp Ensur es tha t the file c ache buff ers ar e flushed .Linux only -cflush Specifies tha t is the hosts file or (for Linux) machine list.all -cnf= Sets the gr aphics dr iver (a vailable drivers v ary by pla tform, and includeall -driver opengl ,x11 , and null for Linux and opengl ,msw , and null for Windo ws). Show en vironmen t variables . all -env Run without the GUI or gr aphics . all -g Specifies the numb er of GPGPU s per machine tha t should b e used f or AMG acceleration. Only a vailable in par allel.Linux and Win64 only-gpgpu= Run without gr aphics . all -gr Run without the GUI but with gr aphics . You c annot in teract with the displa yed graphics objec ts.all -gu 47Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Starting ANSY S Fluen tDescr iption Platform Option Specifies tha t is used f or running C ortex (the pr ocess tha t manages the GUI and gr aphics).Linux only -gui_machine= Displa y command line options . all -help Run in minimiz ed mo de. Windo ws only -hidden Specifies tha t the IP in terface is to be used b y the host.all -host_ip= Reads the sp ecified jour nal file(s). Read multiple jour nals a t onc e as f ollows:-iall -i example1.jou -i example2.jou -i example3.jou ... AAS Mo de does not supp ort multiple journals fr om the c ommand line . Start Fluen t in meshing mo de (y ou must sp ecify F luen t as either 3d or 3ddp).all -meshing Specifies tha t the MPI implemen tation is ibmmpi|intel|... .all -mpi= Launches an MPI pr ogram t o collec t network performanc e da ta and pr intsall -mpitest to console (Linux) or t o the w orking directory (Windo ws). Do not displa y mesh af ter reading . all -nm Specify in terconnec t;={default | eth | ib}all -p Check the net work connec tions b efore spawning c omput e no des.Linux only -pcheck Loads a binar y tha t is sp ecially p orted for a par ticular pla tform, as descr ibed in Performanc e Options (p.51).Linux only -platform= Run the ANSY S Fluen t postpr ocessing-only e xecutable .all -post List all r eleases installed in the cur rent directory.all -r Run r elease of ANSY S Fluen t. all -r Specify the machine t o be used f or executing mpir un t o launch the no deLinux only -remote_node= processes; if = is omitt ed, the first no de in the hosts file will b e used . Run ANSY S Fluen t under a scheduler ; can b e set t o lsfLinux only -scheduler= (LSF),pbs (PBS P rofessional), or sge (Univa Grid Engine—f ormer ly Sun G rid Engine). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 48Starting and Ex ecuting ANSY S Fluen tDescr iption Platform Option Enables an additional option that is r elevant for the selec tedLinux only -scheduler_opt= scheduler ; this c ommand line option can b e included multiple times . Sets the par allel en vironmen t to when r unning under SGE .Linux only -scheduler_pe= Sets the scheduler queue t o . Linux only -scheduler_queue= Enables a job-scheduler-supp orted native remot e no de acc ess mechanism.Linux only -scheduler_tight_coupling Sets the en vironmen t variable to .all -setenv="=" Run ANSY S Fluen t and star t the r emot e visualiza tion ser ver.You c an pr ovide aall -sifile=.txt path b efore the ser ver inf o filename t o specify wher e the file is cr eated. Prints the memor y band width. Linux only -stream Specifies tha t the numb er of pr ocessors is .all -t Specifies tha t the numb er of pr ocessors for meshing is .all -tm 4.1.4.1. ACT O ption fluent -act loads ANSY S ACT a t Fluen t star tup. For additional inf ormation ab out A CT in F luen t, see Customizing F luen t in the Fluent U ser's G uide (p.3233 ). 4.1.4.2. Applic ation O ption fluent -app , when set equal t o flremote , launches either the F luen t Launcher or the sp ecified dimension of F luen t (for e xample , 3ddp), along with the F luen t Remot e Visualiza tion C lient. For addi- tional inf ormation ab out the F luen t Remot e Visualiza tion C lient, refer to Remot e Visualiza tion and Accessing F luen t Remot ely (p.4017 ). 4.1.4.3. Applic ation Script O ption fluent -appscript , allo ws you t o sp ecify a scr ipt tha t will r un in the sp ecified applic ation (-appscript must b e used in c onjunc tion with -app ). 4.1.4.4. Graphics O ptions Note Fluen t aut oma tically selec ts the b est gr aphics dr iver for the giv en r untime en vironmen t, unless y ou cho ose a sp ecific gr aphics dr iver with the fluent -driver command line option. 49Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Starting ANSY S Fluen tfluent -driver allo ws you t o sp ecify the gr aphics dr iver to be used in the session. When enabling graphics displa y, you ha ve various options: on Linux, the a vailable dr ivers include fluent -driver opengl and fluent -driver x11 ; on Windo ws, the a vailable dr ivers include fluent -driver opengl and fluent -driver msw (the la tter instr ucts ANSY S Fluen t to use the Op erating S ystems Windo ws dr iver). For b oth Linux and Windo ws, you c an disable gr aphics displa y using fluent - driver null . For a c ompr ehensiv e list of the dr ivers a vailable t o you, open a F luen t session, enter the display/set/rendering-options/driver text command , and then pr ess the Enter key at the driver> prompt. For mor e details ab out using the dr iver options , see Hiding the G raphics Windo w D ispla y (p.2815 ) in the User's G uide (p.1). Note For an y session tha t displa ys graphics in a gr aphics windo w and/or sa ves pic ture files , having the dr iver set t o x11 ,msw , or null will c ause the r ender ing / sa ving sp eed t o be signific antly slo wer. fluent -gui_machine= will r un C ortex on a sp ecified machine ( ). This option is only a vailable when r unning on Linux, and ma y be needed t o ensur e optimal gr aphics performanc e when r unning F luen t under a scheduler / load manager (using the -scheduler= option, as descr ibed in Scheduler Options (p.53)). Imp ortant (Exceed onD emand Only) When y ou ar e using the -gui_machine flag y ou must also use -setenv="CORTEX_PRE=ssrun" to sp ecify the ser ver side r ender ing t o ensur e acc el- erated gr aphics p erformanc e. For e xample:fluent 3ddp -t2 -setenv="CORTEX_PRE=/opt/Exceed_connec- tion_server_13.8_64/bin/ssrun" -scheduler= -sched- uler_queue= -gui_machine= Note tha t the pa th to ssrun ma y be diff erent for y our sp ecific en vironmen t. fluent -g will r un C ortex without gr aphics and without the gr aphic al user in terface.This option is useful if w ant to submit a ba tch job . fluent -gr will r un C ortex without gr aphics .This option c an b e used in c onjunc tion with the -i option t o run a job in “back ground ” mo de. fluent -gu will r un C ortex without the gr aphic al user in terface but will op en gr aphics windo ws and displa y gr aphics objec ts.You c annot in teract with the displa yed gr aphics objec ts. To star t Fluen t and immedia tely r ead a jour nal file , type fluent -i , replacing with the name of the jour nal file y ou w ant to read. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 50Starting and Ex ecuting ANSY S Fluen tfluent -nm will r un C ortex without displa ying the mesh in the gr aphics windo w. Imp ortant Download gr aphics c ard dr iver up dates dir ectly fr om the gr aphics c ard vendor's w ebsit e, for e xample www .nvidia.c om. Do not use the "U pdate Driver" f eature off ered b y the op er- ating sy stem as these c an sometimes up date to an older v ersion of the dr iver. 4.1.4.5. Meshing Mo de O ption fluent -meshing specifies tha t Fluen t op ens in meshing mo de r ather than the default solution mode. See the Fluen t User’s Guide (p.1) for fur ther details ab out the meshing mo de. 4.1.4.6. Performanc e O ptions -cflush specifies tha t memor y is allo cated in such a w ay as t o ensur e tha t all of the asso ciated file cache buff ers ar e flushed .This ma y resolv e pr ocessing p erformanc e issues . For mor e details , see Clearing the Linux F ile C ache B uffers (p.3103 ) in the User's G uide (p.1). -platform= loads a binar y tha t is sp ecially p orted f or a par ticular pla tform.When =intel , an A VX2 optimiz ed binar y is used tha t enhanc es p erformanc e when r unning on pr ocessors tha t supp ort the A VX2 instr uction set (a vailable only on Linux). -stream prints the memor y band width, using a v ariant of the STREAM b enchmar k.This inf ormation can b e helpful in det ermining if y our memor y is set up in an optimal manner . 4.1.4.7. Parallel O ptions These options ar e used in asso ciation with the par allel solv er. -affinity= specifies the pr ocess binding (affinit y) setting , except when the M icrosof t MPI is used in Windo ws—in tha t case, the M icrosof t MPI affinit y setting is alw ays used; for all other c ases , process binding is enabled b y default and c an b e disabled b y setting =off (except when the Intel MPI is used on Windo ws, in which c ase the In tel MPI affinit y setting is used). When r unning on Linux in e xclusiv e mo de (tha t is, when no other users / jobs ha ve acc ess t o your machine) or on Windo ws, Fluen t will assign the pr ocesses in an optimiz ed manner when pr ocess binding is enabled . When r unning on Linux in non-e xclusiv e mo de, you c an set the affinit y thusly : when =sock (the default), processes ar e bound t o a c ore if no other jobs ar e running on the machine , other wise the y are bound t o a so cket; when =core , processes ar e bound t o a c ore in all c ases . -ccp (wher e is the name of the head no de) r uns the par allel job thr ough the M icrosof t Job Scheduler as descr ibed in Starting P arallel ANSY S Fluen t with the M icrosof t Job Scheduler (p.3061 ) in the User's G uide (p.1). -cnf= (wher e is the name of a hosts file or a list of Linux machines) spa wns a c omput e node on each of the sp ecified machines . For details , see Starting P arallel ANSY S Fluen t on a Windo ws System U sing C ommand Line Options (p.3058 ) or Starting P arallel ANSY S Fluen t on a Linux S ystem Using C ommand Line Options (p.3064 ) in the User's G uide (p.1). -gpgpu= specifies the numb er of gener al pur pose gr aphics pr ocessing units (GPGPU s) per machine to be used f or AMG acc eleration. For mor e inf ormation, see Using G ener al Purpose G raphics P rocessing Units (GPGPU s) With the A lgebr aic M ultigr id (AMG) S olver in the Fluent U ser's G uide (p.3093 ). 51Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Starting ANSY S Fluen t-host_ip= specifies the IP in terface to be used b y the host pr ocess. -mpi= specifies tha t is to be used f or the MPI. You c an sk ip this flag if y ou cho ose t o use the default MPI. -mpiopt= allo ws you t o sp ecify an y additional MPI flags ( ) to be included in the r un (Linux only). -mpitest runs the mpit est pr ogram inst ead of ANSY S Fluen t to test the net work. -p specifies the use of par allel in terconnec t , wher e can b e an y of the in terconnec ts listed in Starting P arallel ANSY S Fluen t on a Windo ws System U sing C ommand Line Options (p.3058 ) or Starting P arallel ANSY S Fluen t on a Linux S ystem U sing C ommand Line Options (p.3064 ) in the User's Guide (p.1). -pcheck checks the net work connec tions b efore spa wning c omput e no des (Linux only). By default , the mpir un c ommand (which launches the no de pr ocesses) is e xecut ed on the c omput e node wher e the host pr ocess is spa wned .You c an use -remote_node= to sp ecify a different machine f or the e xecution of this c ommand . If = is omitt ed, the first no de in the hosts file will b e used . (Linux only) -ssh specifies tha t SSH should b e used t o spa wn r emot e pr ocesses . (Beginning with ANSY S Fluen t R16.0, SSH is used b y default. This option is included pr imar ily for back ward compa tibilit y with e xisting launch scr ipts, etc.) -t specifies tha t processors ar e to be used . For mor e inf ormation ab out star ting the par allel version of ANSY S Fluen t, see Starting P arallel ANSY S Fluen t on a Windo ws System (p.3058 ) or Starting Parallel ANSY S Fluen t on a Linux S ystem (p.3063 ) in the User's G uide (p.1). -tm specifies tha t processors ar e to be used f or meshing .This v alue must b e less than or equal t o the numb er of pr ocesses sp ecified with -t . 4.1.4.8. Postpr ocessing O ption fluent -post will r un a v ersion of F luen t tha t allo ws you t o set up a pr oblem or p erform p ostpr o- cessing , but will not allo w you t o perform calcula tions . Running ANSY S Fluen t for pr e- and p ostpr o- cessing r equir es y ou t o use the -post flag on star tup.To use this option on Linux, launch ANSY S Fluen t by adding the -post flag af ter the v ersion numb er, for e xample , fluent 3d -post To use this same f eature from the gr aphic al in terface on Windo ws or Linux, selec t the Pre/Post option in the Gener al tab of F luen t Launcher , as descr ibed in Starting ANSY S Fluen t Using F luen t Launch- er (p.33). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 52Starting and Ex ecuting ANSY S Fluen t4.1.4.9. Remot e Visualization O ptions The -sifile=.txt option star ts ANSY S Fluen t and the ser ver tha t is nec essar y for running the r emot e visualiza tion clien t. For additional inf ormation on r emot e visualiza tion, refer to Remot e Visualiza tion and A ccessing F luen t Remot ely (p.4017 ). Note You c an sp ecify the lo cation f or the ser ver inf o file pr ior t o the filename , for e xample -sifile=D:/example_folder/server_info_example_name.txt . If you do not provide a file pa th b efore the file name and y ou do not pr ovide a pa th using the SERV- ER_INFO_DIR environmen t variable , then the file is sa ved in y our w orking dir ectory. 4.1.4.10. Scheduler O ptions The -scheduler= option allo ws you t o sp ecify tha t your Linux session is r un under a scheduler / load manager , wher e can b e one of the f ollowing: •lsf : this allo ws you t o run ANSY S Fluen t under IBM S pectrum LSF sof tware, and ther eby tak e ad vantage of the check pointing f eatures of tha t load managemen t tool. For fur ther details , see Part I: Running F luen t Under LSF . •pbs : this r uns ANSY S Fluen t under A ltair PBS P rofessional, and allo ws you t o use the f eatures of this sof tware to manage y our distr ibut ed c omputing r esour ces. For fur ther details , see Part II: Running F luen t Under PBS P rofessional . •sge : this r uns ANSY S Fluen t under U niva Grid Engine (pr eviously k nown as Sun G rid Engine , or SGE) sof tware, and allo ws you t o use the f eatures of this sof tware to manage y our distr ibut ed computing r esour ces. For fur ther details , see Part III: Running F luen t Under SGE . Note You c an use the -scheduler= option along with the -gui_ma- chine= (descr ibed in Graphics Options (p.49)), in or der t o ensur e optimal graphics p erformanc e. Other options ar e available when y ou use a scheduler : you c an sp ecify a queue using -sched- uler_queue= ; you c an enable an additional option f or the scheduler using -sched- uler_opt= (not e tha t you c an include multiple instanc es of this option when y ou w ant to use mor e than one scheduler option); and when r unning under U niva Grid Engine sof tware, you c an set the par allel en vironmen t using -scheduler_pe= . It is also p ossible t o enable a job-scheduler-supp orted na tive remot e no de acc ess mechanism using -scheduler_tight_coupling in Linux. For details ab out the MPI / job scheduler c ombina tions that are supp orted f or this tigh t coupling , see Running F luen t Using a L oad M anager . 4.1.4.11. Version, Release O ptions , and E nvironment Variables Typing fluent -r , replacing with the desir ed v ersion (2d or 3d, or f or double pr ecision,fluent or 3ddp ), will list all r eleases of the sp ecified v ersion. 53Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Starting ANSY S Fluen tfluent -r will r un r elease of ANSY S Fluen t. Typing fluent -env , replacing with the desir ed v ersion, will list all environmen t variables b efore running ANSY S Fluen t. Including the -setenv="=" option sets the en vironmen t variable explicitly to before launching ANSY S Fluen t. Note tha t you c an include as man y instanc es of this option as y ou need t o set all of the r elevant en vironmen t variables .You c an also unset an en vironmen t variable b y en tering -setenv="=" . 4.1.4.12. System C oupling O ptions The f ollowing c ommand line options (in either Windo ws or Linux) c an b e used when ANSY S Fluen t is in volved in a sy stem c oupling simula tion. -schost="" (wher e is the name of the host machine , in quot es) sp ecifies the host machine on which the c oupling ser vice is r unning (t o which the c o-simula tion par ticipan t/solv er must c onnec t). -scid= (wher e is the session-id of the sy stem c oupling r un, without quot es) sp ecifies the iden tity of the c oupling ser vice run. -sclic= (wher e is the name of the p ort and host machine , without quot es) sp ecifies the port and host of the machine with the sy stem c oupling lic ense r unning (tha t the c o-simula tion par ti- cipan t/solv er must c onnec t to). For e xample ,7468@localhost . -scport= (wher e is the p ort numb er) sp ecifies the p ort on the host machine up on which the c oupling ser vice is list ening f or c onnec tions fr om c o-simula tion par ticipan ts. -scname="" (wher e is the name of the par ticipan t, in quot es) sp ecifies the unique name used b y the c o-simula tion par ticipan t to iden tify itself t o the c oupling ser vice (see System C oupling Server F ile (scServer.scs ) in the System C oupling U ser's G uide for mor e inf ormation). The gener al syn tax f or in voking ANSY S Fluen t for sy stem c oupling is: fluent 3d –schost= host name in quot es–scport= port numb er–scname= name of the sol ver in quot es For instanc e: fluent 3d –schost="machine1.domain.com" –scport=1234 –scname="Solution1" Onc e ANSY S Fluen t loads the c ase, initializ e the solution using the f ollowing c ommand: s i i Onc e your c ase is initializ ed, star t the sy stem c oupling b y typing the f ollowing c ommand in the ANSY S Fluen t text user in terface (TUI): (sc-solve) For mor e inf ormation, see Performing S ystem C oupling S imula tions U sing F luen t (p.3207 ) in the Fluen t User's G uide , as w ell as the System C oupling U ser's G uide . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 54Starting and Ex ecuting ANSY S Fluen t4.1.4.13. Other Star tup O ptions There ar e other star tup options tha t are not list ed when y ou t ype the fluent -help command . These options c an b e used t o cust omiz e your gr aphic al user in terface. For e xample , to change the ANSY S Fluen t windo w siz e and p osition y ou c an either mo dify the .Xdefaults file descr ibed in Modifying the G raphic al U ser In terface (p.573) in the User's G uide (p.1), or y ou c an simply t ype the f ollowing command a t star tup: fluent -geometry x+- wher e and are the width and heigh t in pix els, respectively, and + - is the p os- ition of the windo w. Therefore, typing fluent 3d -geometry 700x500+20-400 will star t the 3D v ersion of ANSY S Fluen t, sizing the ANSY S Fluen t console t o 700x500 pix els and p ositioning it on y our monit or scr een at +20-400. There ar e additional Qt c ommand line star tup options f or mo difying the gr aphic al st ylesheet and mor e, which c an b e found in Qt do cumen tation. 4.2. Running ANSY S Fluen t in B atch M ode ANSY S Fluen t can b e used in teractively, with input fr om and displa y to your c omput er scr een, or it c an be used in a ba tch or back ground mo de in which inputs ar e obtained fr om and outputs ar e stored in files . Gener ally y ou will p erform pr oblem setup , initial c alcula tions , and p ostpr ocessing of r esults in an interactive mo de. However, when y ou ar e ready to perform a lar ge numb er of it erative calcula tions , you ma y want to run ANSY S Fluen t in ba tch or back ground mo de.This allo ws the c omput er resour ces to be pr ioritized, enables y ou t o control the pr ocess fr om a file (elimina ting the need f or y ou t o be presen t dur ing the c alcula tion), and also pr ovides a r ecord of the c alcula tion hist ory (residuals) in an output file .While the pr ocedur es for running ANSY S Fluen t in a ba tch mo de diff er dep ending on y our comput er op erating sy stem, Background Ex ecution on Linux S ystems (p.55) provides guidanc e for running in ba tch/back ground on Linux sy stems , and Background Ex ecution on Windo ws Systems (p.56) provides guidanc e for running in ba tch/back ground on Windo ws systems . For additional inf ormation, see the f ollowing sec tions: 4.2.1. Background Ex ecution on Linux S ystems 4.2.2. Background Ex ecution on Windo ws Systems 4.2.3. Batch Ex ecution Options 4.2.1. Background E xecution on Linux S ystems To run ANSY S Fluen t in the back ground in a C-shell (csh) on a Linux sy stem, type a c ommand of the following f orm a t the sy stem-le vel pr ompt: fluent 2d -g < inputfile > & outputfile & or in a B ourne/K orn-shell, type: fluent 2d -g < inputfile > outputfile 2>&1 & In these e xamples , 55Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Running ANSY S Fluen t in B atch M ode•fluent is the c ommand y ou t ype to run ANSY S Fluen t interactively. •-g indic ates tha t the pr ogram is t o be run without the GUI or gr aphics (see Starting ANSY S Fluen t (p.33)). •inputfile is a file of ANSY S Fluen t commands tha t are iden tical to those tha t you w ould t ype interactively. •outputfile is a file tha t the back ground job will cr eate, which will c ontain the output tha t ANSY S Flu- ent would nor mally pr int to the scr een (f or e xample , the menu pr ompts and r esidual r eports). •& tells the Linux sy stem t o perform this task in back ground and t o send all standar d sy stem er rors (if an y) to outputfile . The file inputfile can b e a jour nal file cr eated in an ear lier ANSY S Fluen t session, or it c an b e a file that you ha ve created using a t ext edit or. In either c ase, the file must c onsist only of t ext interface commands (sinc e the GUI is disabled dur ing ba tch e xecution). A typic al inputfile is sho wn b elow: ; Read case file rc example.cas ; Initialize the solution /solve/initialize/initialize-flow ; Calculate 50 iterations it 50 ; Write data file wd example50.dat ; Calculate another 50 iterations it 50 ; Write another data file wd example100.dat ; Exit Fluent exit yes This e xample file r eads a c ase file example.cas , initializ es the solution, and p erforms 100 it erations in two gr oups of 50, saving a new da ta file af ter each 50 it erations .The final line of the file t ermina tes the session. Note tha t the e xample input file mak es use of the standar d aliases f or reading and wr iting case and da ta files and f or it erating . (it is the alias f or /solve/iterate ,rc is the alias f or /file/read-case ,wd is the alias f or /file/write-data , etc.) These pr edefined aliases allo w you t o execut e commonly used c ommands without en tering the t ext menu in which the y are found . In gener al, ANSY S Fluen t assumes tha t input b eginning with a / star ts in the t op-le vel text menu , so if you use an y text commands f or which aliases do not e xist, you must b e sur e to type in the c omplet e name of the c ommand (f or e xample ,/solve/initialize/initialize-flow ). Note also tha t you c an include c ommen ts in the file . As in the e xample ab ove, commen t lines must b egin with a ; (semic olon). An alt ernate str ategy for submitting y our ba tch r un, as f ollows, has the ad vantage tha t the outputfile will c ontain a r ecord of the c ommands in the inputfile . In this appr oach, you w ould submit the batch job in a C-shell using: fluent 2d -g -i inputfile >& outputfile & or in a B ourne/K orn-shell using: fluent 2d -g -i inputfile > outputfile 2>&1 & 4.2.2. Background E xecution on Windo ws Systems To run ANSY S Fluen t in the back ground on a Windo ws system, the f ollowing c ommands c an b e used: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 56Starting and Ex ecuting ANSY S Fluen tfluent 3d -g -i journal fluent 3d -g -wait -i journal fluent 3d -hidden -i journal In these e xamples , •fluent is the c ommand y ou t ype to run ANSY S Fluen t interactively. •-g indic ates tha t the pr ogram is t o be run minimiz ed in the task bar . •-i journal reads the sp ecified jour nal file . •-wait is the c ommand y ou t ype in a DOS ba tch file or some other scr ipt in a situa tion wher e the scr ipt must w ait un til ANSY S Fluen t has c omplet ed its r un. •-hidden is similar t o the -wait command , but also r uns ANSY S Fluen t complet ely hidden and non-in ter- actively. To get an output (or tr anscr ipt) file while r unning ANSY S Fluen t in the back ground on a Windo ws system, the jour nal file must c ontain the f ollowing c ommand t o wr ite a tr anscr ipt file: ; start transcript file /file/start-transcript outputfile.trn wher e the outputfile is a file tha t the back ground job will cr eate, which will c ontain the output that ANSY S Fluen t would nor mally pr int to the scr een (f or e xample , the menu pr ompts and r esidual reports). See Creating and R eading J ournal F iles (p.597) in the User's G uide (p.1) for details ab out jour nal files . See Creating Transcr ipt F iles (p.601) in the User's G uide (p.1) for details ab out tr anscr ipt files . 4.2.3. Batch E xecution Options During a t ypic al session, ANSY S Fluen t ma y requir e feedback fr om y ou in the e vent of a pr oblem it encoun ters. ANSY S Fluen t usually c ommunic ates pr oblems or questions thr ough the use of Error dialo g boxes,Warning dialo g boxes, or Question dialo g boxes.While e xecuting ANSY S Fluen t in ba tch mo de, you ma y want to suppr ess this t ype of in teraction in or der t o, for e xample , create jour nal files mor e easily . There ar e thr ee c ommon ba tch c onfigur ation options a vailable t o you when r unning ANSY S Fluen t in batch mo de.You c an acc ess these options using the Batch Options dialo g box (Figur e 4.6: The B atch Options D ialog Box (p.58)). File → Batch Options ... 57Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Running ANSY S Fluen t in B atch M odeFigur e 4.6: The B atch Options D ialo g Box The Batch Options dialo g box contains the f ollowing it ems: Confir m F ile O verwrite determines whether ANSY S Fluen t confir ms a file o verwrite.This option is tur ned on b y default. Hide Q uestions allows you t o hide Question dialo g boxes.This option is tur ned off b y default. Exit on E rror allows you t o aut oma tically e xit fr om ba tch mo de when an er ror o ccurs .This option is disabled b y default. When r un in ba tch mo de thr ough the c ommand pr ompt or a jour nal file with Exit on E rror enabled , Fluen t will e xit under the f ollowing cir cumstanc es: •Normal r un t ermina tion up on r eaching the end of a jour nal (r etur n value 0) •Error retur ned dur ing scr ipted t ext command e xecution (r etur n value 1) •Unexpected input (wr ong t ype) to text command (r etur n value 1) •Licensing er ror (r etur n value 2) If an in valid t ext command is en tered, Fluen t will not e xit, but pr oceed t o the ne xt text input. Note that in Windo ws you must star t Fluent with the -wait command line option. file → set-batch-options Any combina tion of these options c an b e tur ned on or off a t an y giv en time pr ior t o running in ba tch mode. Imp ortant Batch option settings ar e not saved with c ase files .They are mean t to apply f or the dur ation of the cur rent ANSY S Fluen t session only . If you r ead in additional mesh or c ase files dur ing this session, the ba tch option settings will not b e alt ered. As ba tch options ar e not sa ved with c ase files , jour nal files de velop ed f or use in ba tch mo de should b egin b y enabling the desir ed ba tch option settings (if diff erent from the default settings). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 58Starting and Ex ecuting ANSY S Fluen t4.3. Switching B etween M eshing and S olution M odes You c an swit ch fr om the meshing mo de of F luen t to the solution mo de b y click ing the Switch t o Solution butt on, located b y default in the t op lef t corner of the applic ation windo w.The mesh fr om your meshing mo de session will b e transf erred and r ead in the new solution mo de session. You c an swit ch fr om the solution mo de of F luen t to the meshing mo de b y using the switch-to- meshing-mode text command . Note tha t this t ext command is only a vailable f or 3D sessions , before you ha ve read a mesh or c ase file . 4.4. Check pointing an ANSY S Fluen t Simula tion The check pointing f eature of ANSY S Fluen t allo ws you t o sa ve case and da ta files while y our simula tion is running .While similar t o the aut osave feature of ANSY S Fluen t (Automa tic S aving of C ase and D ata Files (p.591) in the User's G uide (p.1)), which allo ws you t o sa ve files thr oughout a simula tion, check- pointing allo ws you sligh tly mor e control in tha t you c an sa ve an ANSY S Fluen t job e ven af ter y ou ha ve started the job and did not set the aut osave option. Check pointing also allo ws you t o sa ve case and data files and then e xit out of ANSY S Fluen t.This f eature is esp ecially useful when y ou need t o stop an ANSY S Fluen t job abr uptly and sa ve its da ta. There ar e two diff erent ways to check point an ANSY S Fluen t simula tion, dep ending up on ho w the simula tion has b een star ted. 1.ANSY S Fluen t running under LSF or SGE ANSY S Fluen t is in tegrated with load managemen t tools lik e LSF and SGE .These t wo tools allo w you t o check point an y job r unning under them. You c an use the standar d metho d pr ovided b y these t ools t o check point the ANSY S Fluen t job . For mor e inf ormation on using ANSY S Fluen t and SGE or LSF , see Part III: Running F luen t Under SGE or Part I: Running F luen t Under LSF , respectively. 2.Indep enden tly r unning ANSY S Fluen t When not using t ools such as LSF or SGE , a diff erent check pointing mechanism c an b e used when running an ANSY S Fluen t simula tion. You c an check point an ANSY S Fluen t simula tion while it erat- ing/time-st epping , so tha t ANSY S Fluen t saves the c ase and da ta files and then c ontinues the c alcu- lation, or so tha t ANSY S Fluen t saves the c ase and da ta files and then e xits. •Saving c ase and da ta files and c ontinuing the c alcula tion: On Linux, create a file c alled check-fluent , tha t is, /tmp/check-fluent On Windo ws, create a file c alled check-fluent.txt , tha t is, C:\temp\check-fluent.txt •Saving c ase and da ta files and e xiting ANSY S Fluen t: On Linux, create a file c alled exit-fluent , tha t is, /tmp/exit-fluent 59Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Check pointing an ANSY S Fluen t Simula tionOn Windo ws, create a file c alled exit-fluent.txt , tha t is, C:\temp\exit-fluent.txt The sa ved c ase and da ta files will ha ve the cur rent iteration numb er app ended t o their file names . ANSY S Fluen t off ers an alt ernate way to check point an unst eady simula tion. While the default b eha- vior is t o check point the simula tion a t the end of the cur rent iteration, for unst eady simula tions y ou have the option of c ompleting all of the it erations in the cur rent time-st ep b efore check pointing . This c an b e set b y en tering the f ollowing Scheme c ommand pr ior t o running the unst eady simula tion: (ckpt/time-step? #t) Now when y ou sa ve the check point file (as descr ibed pr eviously), the c ase and da ta file will b e sa ved at the end of the cur rent time st ep and named acc ordingly .To swit ch back t o the default check- pointing mechanism a t the end of the cur rent iteration, use the f ollowing Scheme c ommand: (ckpt/time-step? #f) Imp ortant Note tha t the (ckpt/time-step? #t) command will ha ve the eff ect only in the c ase of an unst eady simula tion. Note It is r ecommended tha t you do not use check pointing when using ANSY S Fluen t in Workbench. However, if check pointing is nec essar y, the exit-fluent/exit-fluent.txt file c an be used and the file will b e check ed in its default lo cation (the FFF/FLU system dir ectory containing the *.set file) . If ANSY S Fluen t is c alcula ting , then the e xistence of the file is equiv alen t to an interrupt command . Similar ly, the check-fluent/check-fluent.txt file c an b e used t o sa ve the pr ojec t on demand when ANSY S Fluen t is c alcula ting . 4.5. Cleaning U p Processes F rom an ANSY S Fluen t Simula tion ANSY S Fluen t lets y ou easily r emo ve extraneous pr ocesses in the e vent tha t an ANSY S Fluen t simula tion must b e stopp ed. When a session is star ted, ANSY S Fluen t creates a cleanup-fluent script file .The scr ipt c an b e used to clean up all ANSY S Fluen t-related pr ocesses . ANSY S Fluen t creates the cleanup-scr ipt file in the cur rent working dir ectory with a filename tha t includes the machine name and the pr ocess iden tification numb er (PID) (f or e xample ,cleanup-fluent-mymachine-1234 ). If the cur rent dir ectory do es not p ossess the pr oper wr ite permissions , then ANSY S Fluen t will wr ite the cleanup-scr ipt file t o your home dir ectory. If, for e xample , ANSY S Fluen t is star ted on a machine c alled thor and the pr ocess iden tification numb er is 32895 , ANSY S Fluen t will cr eate a cleanup-scr ipt c alled cleanup-fluent-thor-32895 in the current dir ectory.To run the cleanup-scr ipt, and clean up all ANSY S Fluen t processes r elated t o your session, on Linux pla tforms, type the f ollowing c ommand in the c onsole windo w: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 60Starting and Ex ecuting ANSY S Fluen tsh cleanup-fluent-thor-32895 Or, if the shell scr ipt alr eady has e xecutable p ermissions , simply t ype: cleanup-fluent-thor-32895 To clean up e xtraneous ANSY S Fluen t processes on Windo ws (ser ial or par allel), double-click the c orres- ponding ba tch file (f or e xample ,cleanup-fluent-thor-32895.bat ) tha t ANSY S Fluen t gener ates at the b eginning of each session. Imp ortant During a nor mal r un, this file will b e delet ed aut oma tically af ter e xiting ANSY S Fluen t. In abnor mal situa tions , you ma y use this ba tch file t o clean up the ANSY S Fluen t processes . Onc e an ANSY S Fluen t session has b een closed , you c an saf ely delet e an y lef t over cleanup scripts fr om y our w orking dir ectory. Imp ortant If an ANSY S Fluen t session hangs or fr eezes on Windo ws, and y ou w ant to view the c omplet e contents of the ANSY S Fluen t console output in a tr anscr ipt file , you should use the taskkill command thr ough the DOS c ommand pr ompt , rather than t ermina ting the ANSY S Fluen t applic ation thr ough the Windo ws Task M anager . 4.6. Exiting ANSY S Fluen t You c an e xit ANSY S Fluen t by selec ting Exit in the File ribbon tab . If the pr esen t sta te of the pr ogram has not b een wr itten t o a file , a Question dialo g box will op en t o confir m if y ou w ant to pr oceed.You can c ancel the e xit and wr ite the appr opriate file(s) or y ou c an c ontinue t o exit without sa ving the c ase or da ta. 61Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Exiting ANSY S Fluen tRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 62Glossar y of Terms This glossar y contains a listing of t erms c ommonly used thr oughout the do cumen tation. •adaption (p.63) •case files (p.63) •cell types (p.64) •computa tional fluid d ynamics (CFD) (p.64) •console (p.65) •convergenc e (p.65) •cortex (p.65) •data files (p.65) •dialo g boxes (p.65) •discr etiza tion (p.65) •GUI (p.65) •mesh (p.65) •models (p.65) •node (p.65) •postpr ocessing (p.65) •residuals (p.65) •skewness (p.65) •solv ers (p.66) •terminal emula tor (p.66) •TUI (p.66) adaption A technique useful in impr oving o verall mesh qualit y.The solution-adapt- ive mesh r efinemen t feature of ANSY S Fluen t allo ws you t o refine and/or coarsen y our mesh based on geometr ic and numer ical solution da ta. In addition, ANSY S Fluen t provides t ools f or cr eating and viewing adaption fields cust omiz ed t o par ticular applic ations . case files Files tha t contain the mesh, boundar y conditions , and solution par amet ers for a pr oblem. A c ase file also c ontains the inf ormation ab out the user interface and gr aphics en vironmen t. 63Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.cell t ypes The v arious shap es or units tha t constitut e the base elemen ts of a mesh. ANSY S Fluen t can use meshes c omp osed of t etrahedr al, hexahedr al, pyramid , wedge , or p olyhedr al cells (or a c ombina tion of these). Figur e 8: Cell Types computa tional fluid d ynam- ics (CFD)The scienc e of pr edic ting fluid flo w, hea t transf er, mass tr ansf er (as in perspir ation or dissolution), phase change (as in fr eezing or b oiling), chemic al reaction (f or e xample , combustion), mechanic al mo vemen t (for example , fan r otation), stress or def ormation of r elated solid str uctures (such as a mast b ending in the wind), and r elated phenomena b y solving Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 64Glossar y of Termsthe ma thema tical equa tions tha t go vern these pr ocesses using a numer- ical algor ithm on a c omput er. console The c onsole is par t of the ANSY S Fluen t applic ation windo w tha t allo ws for text command input and the displa y of inf ormation. convergenc e The p oint at which the solution is no longer changing with each succ ess- ive iteration. Convergenc e cr iteria, along with a r educ tion in r esiduals , also help in det ermining when a solution is c omplet e. Convergenc e cr i- teria ar e pr e-set c onditions on the r esiduals tha t indic ate tha t a c ertain level of c onvergenc e has b een achie ved. If the r esiduals f or all pr oblem variables fall b elow the c onvergenc e cr iteria but ar e still in decline , the solution is still changing t o a gr eater or lesser degr ee. A b etter indic ator occurs when the r esiduals fla tten in a tr aditional r esidual plot (of r esidual value v s. iteration). This p oint, sometimes r eferred t o as c onvergenc e at the le vel of machine accur acy, tak es time t o reach, however, and ma y be beyond y our needs . For this r eason, alternative tools such as r eports of forces, hea t balanc es, or mass balanc es c an b e used inst ead. cortex A utilit y tha t manages ANSY S Fluen t’s user in terface and basic gr aphic al func tions . data files Files tha t contain the v alues of the flo w field in each gr id elemen t and the c onvergenc e hist ory (residuals) f or tha t flo w field . dialo g boxes The separ ate windo ws tha t are used lik e forms t o perform input tasks . Each dialo g box is unique and emplo ys various t ypes of input c ontrols that mak e up the f orm. discr etiza tion The ac t of r eplacing the diff erential equa tions tha t go vern fluid flo w with a set of algebr aic equa tions tha t are solv ed a t distinc t points. GUI The gr aphic al user in terface, which c onsists of the main ANSY S Fluen t applic ation windo w, dialo g boxes, graphics windo ws, etc. mesh A collec tion of p oints represen ting the flo w field , wher e the equa tions of fluid motion (and t emp erature, if relevant) ar e calcula ted. models Numer ical algor ithms tha t appr oxima te ph ysical phenomenon (f or e x- ample , turbulenc e). node The distinc t points of a mesh (p.65) at which the equa tions of fluid motion ar e solv ed. postpr ocessing The ac t of analyzing the numer ical results of y our CFD simula tion using reports, integrals, and gr aphic al analy sis t ools such as c ontour plots , an- imations , etc. residuals The small imbalanc e tha t is cr eated dur ing the c ourse of the it erative solution algor ithm. This imbalanc e in each c ell is a small, non-z ero value that, under nor mal cir cumstanc es, decr eases as the solution pr ogresses . skewness The diff erence between the shap e of the c ell and the shap e of an equi- lateral cell of equiv alen t volume . Highly sk ewed c ells c an decr ease accur- acy and destabiliz e the solution. 65Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.solv ers ANSY S Fluen t has t wo distinc t solv ers, based on numer ical pr ecision (single-pr ecision v s. double-pr ecision). Within each of these c ategor ies, ther e ar e solv er formula tions: pressur e based; densit y based e xplicit; and densit y based implicit. terminal emula tor See console (p.65). TUI The t ext user in terface, which c onsists of t extual c ommands tha t can b e entered in to the t erminal emula tor. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 66Glossar y of TermsPart II: Meshing M ode The sec tion descr ibes ho w to use ANSY S Fluen t in meshing mo de. •Introduc tion t o M eshing M ode in F luen t (p.69) introduces the meshing mo de in F luen t and giv es an o verview of its c apabilities . •Starting F luen t in M eshing M ode (p.71) provides instr uctions f or star ting F luen t in meshing mo de. •Graphic al U ser In terface (p.75) descr ibes the use of the gr aphic al user in terface and e xplains ho w to use the online help sy stem. •Text User In terface (p.99) introduces the t ext-based user in terface. •Reading and Writing F iles (p.101) descr ibes the file t ypes tha t can b e read and wr itten (including pic ture files) and giv es details f or imp orting C AD geometr y. •Working With F luen t Guided Workflows (p.123) descr ibes the guided meshing w orkflows tha t mak e it easier to gener ate a v olume mesh star ting fr om C AD geometr ies. •CAD A ssemblies (p.199) descr ibes additional t ools f or imp orted C AD da ta in F luen t Meshing . •Size Functions and Sc oped S izing (p.207) descr ibes ho w to control the mesh siz e distr ibution on a sur face or within the v olume . •Objec ts and M aterial P oints (p.223) descr ibes the use of objec ts and ma terial p oints for iden tifying the mesh region. •Objec t-Based Sur face Meshing (p.239) descr ibes the objec t-based w orkflow for gener ating a c onformal, connec ted sur face mesh. •Objec t-Based Volume M eshing (p.263) descr ibes ho w to fill the go od qualit y sur face mesh with t et, hexcore, poly, or h ybrid volume mesh. •Manipula ting the B oundar y Mesh (p.273) explains the need f or a high-qualit y boundar y mesh and descr ibes the v arious options a vailable f or cr eating such meshes . •Wrapping O bjec ts (p.325) descr ibes the option f or cr eating a high-qualit y boundar y mesh star ting fr om bad surface mesh using the b oundar y wr app er tool. •Creating a M esh (p.341) descr ibes the z one-based meshing str ategy and the cr eation of p yramids , non- conformals , and hea t exchanger meshes . •Gener ating P risms (p.367) descr ibes the pr ocedur e to create infla tion la yers in y our v olume mesh. It also explains ho w to deal with c ommon pr oblems tha t can b e fac ed while cr eating pr isms . •Gener ating Tetrahedr al M eshes (p.399) descr ibes the meshing pr ocedur es for tetrahedr al meshes . •Gener ating the H excore Mesh (p.413) descr ibes the pr ocedur e and options f or cr eating C artesian c ells in the in terior of the domain.•Gener ating P olyhedr al M eshes (p.423) descr ibes the pr ocedur e and options f or cr eating p olyhedr al meshes . •Gener ating P oly-H excore Meshes (p.429) descr ibes the pr ocedur e and options f or cr eating p oly-he xcore meshes . •Gener ating the C utCell M esh (p.433) descr ibes the C utCell meshing pr ocedur e and options a vailable f or CutCell meshing . •Impr oving the M esh (p.451) descr ibes the options a vailable f or impr oving the qualit y of a v olume mesh. •Examining the M esh (p.475) descr ibes the metho ds a vailable f or e xamining the mesh gr aphic ally. •Determining M esh S tatistics and Q ualit y (p.491) descr ibes metho ds for check ing the mesh diagnostic ally. •Appendix A: Imp orting B oundar y and Volume M eshes (p.505) descr ibes filt ers tha t you c an use t o convert data fr om v arious sof tware pack ages t o a f orm tha t can b e read. •Appendix B: Mesh F ile F ormat (p.511) descr ibes the f ormat of the mesh file . •Appendix C: Shortcut Ke ys (p.527) lists all the hot-k eys (shor tcut k eys) available . •Biblio graph y (p.539) presen ts the biblio graph y for the pr evious chapt ers.Chapt er 1: Introduc tion t o M eshing M ode in F luen t When in meshing mo de, Fluen t func tions as a r obust , unstr uctured mesh gener ation pr ogram tha t can handle meshes of vir tually unlimit ed siz e and c omple xity. Meshes ma y consist of t etrahedr al, hexahedr al, polyhedr al, prisma tic, or p yramidal c ells. Unstr uctured mesh gener ation t echniques c ouple basic geo- metr ic building blo cks with e xtensiv e geometr ic da ta to aut oma te the mesh gener ation pr ocess. A numb er of t ools ar e available f or check ing and r epair ing the b oundar y mesh t o ensur e a go od star ting point for gener ating the v olume mesh. The v olume mesh c an b e gener ated fr om the b oundar y mesh using one of the appr oaches descr ibed. The user in terface is wr itten in the Scheme language , which is a dialec t of LISP . Most f eatures ar e ac- cessible thr ough the gr aphic al in terface or the in teractive menu in terface.The ad vanced user c an cus- tomiz e and enhanc e the in terface by adding or changing the Scheme func tions . 1.1. Meshing A ppr oach There ar e two pr incipal appr oaches t o cr eating meshes in ANSY S Fluen t Meshing: •Gener ate a t etrahedr al, hexcore, or h ybrid volume mesh fr om an e xisting b oundar y mesh. In this c ase, you can imp ort a b oundar y mesh fr om ANSY S Meshing or a thir d-par ty mesh gener ation pack age.You c an imp ort boundar y meshes cr eated in C AD/C AE pack ages b y using the appr opriate menu it em in the File → Imp ort submenu (or the asso ciated t ext commands), or y ou c an c onvert them using the appr opriate stand-alone grid filt er. •Gener ate a t etrahedr al, hexcore, or h ybrid volume mesh based on meshing objec ts fr om a fac eted geometr y (from C AD or the .tgf format from ANSY S Meshing). In this c ase, you need t o create a c onformally c onnec ted surface mesh using the objec t wr apping and sewing op erations b efore gener ating the v olume mesh. You can alt ernatively use the C utCell mesher t o dir ectly cr eate a he x-dominan t volume mesh f or the geometr y (imp orted fr om C AD or the .tgf format from ANSY S Meshing) based on meshing objec ts. When the mesh gener ation is c omplet e, you c an tr ansf er the mesh t o solution mo de using the M ode toolbar or the c ommand switch-to-solution-mode .The r emaining op erations—such as setting boundar y conditions , defining fluid pr operties, executing the solution, and viewing and p ostpr ocessing the r esults—ar e performed in solution mo de (see the User’s Guide (p.1) for details). 1.2. Meshing M ode C apabilities When in meshing mo de, Fluen t: •Functions as a r obust , unstr uctured v olume mesh gener ator •Gener ates v olume meshes tha t can b e transf erred t o solution mo de in F luen t •Uses the D elauna y triangula tion metho d for tetrahedr a •Uses the ad vancing la yer metho d for pr isms •Gener ates he xcore mesh •Has a r obust sur face wr app er tool 69Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.•Includes siz e func tions tha t can pr oduce ideal siz e distr ibutions f or man y CFD c alcula tions •Can dir ectly cr eate a he x-dominan t mesh on fac eted geometr y (using the C utCell mesher) •Can e xport polyhedr al cells •Has t ools f or check ing, repair ing, and impr oving b oundar y mesh t o ensur e a go od star ting p oint for the volume mesh •Can manipula te fac e/cell z ones •Is fle xible—it allo ws the most appr opriate cell type to be used t o gener ate the v olume mesh: –Tet meshes ar e suitable f or comple x geometr ies. –Hexcore meshes c an c ombine the fle xibilit y of t et, hex, and pr ism meshes with a smaller c ell c oun t and higher he x-to-tet ratio. –CutCell (he x-dominan t) meshes c an b e dir ectly cr eated fr om fac eted geometr y and c an also b e combined with pr ism la yers. •Has h ybrid meshes: –Prism la yers near w alls allo w pr oper b oundar y layer resolution. –Allows flo w alignmen ts with mesh lines . –Gener ates smaller v olume mesh with highly str etched pr isma tic elemen ts. •Has non-c onformal meshes: –Suitable f or studies in volving selec tive replac emen t of par ts. –Meshes gener ated separ ately c an b e glued t ogether . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 70Introduction t o Meshing M ode in F luen tChapt er 2: Starting F luen t in M eshing M ode Starting F luen t in meshing mo de is acc omplished b y enabling the Meshing M ode check box under Options in the F luen t Launcher , or b y adding the dir ective -meshing when using the c ommand line interface. See Starting and Ex ecuting ANSY S Fluen t (p.33) in the Fluen t Getting S tarted G uide for full details on setting dimension and other options f or star ting in meshing mo de. The .t grid F ile When star ting up in meshing mo de, Fluen t looks in y our home dir ectory for an optional file c alled .tgrid .This file is then loaded using the Scheme func tion load .You c an use the .tgrid file t o cust omiz e the op eration of the c ode in meshing mo de. For e xample , the Scheme func tion ti-menu-load-string is used t o include t ext commands in the .tgrid file. If the .tgrid file c ontains (ti-menu-load-string "file read-case test.cas") , then the c ase file test.cas will b e read in. For mor e details ab out the func tion ti-menu-load- string , see Text Menu Input fr om C haracter S trings in the Fluent Text Command List . Imp ortant Another optional file ,.fluent , if pr esen t, is also loaded a t star t up .This file ma y contain Scheme func tions tha t cust omiz e the op eration of the c ode in solution mo de.When b oth the .tgrid and .fluent files ar e pr esen t, the .fluent file will b e loaded first , followed by the .tgrid file, when the meshing mo de is launched . Hence, the func tions in the .tgrid file will tak e pr ecedenc e over those in the .fluent file f or the meshing mo de. The .fluent file is not loaded again aut oma tically when swit ching t o solution mo de fr om meshing mo de.You will need t o load the file separ ately using the Scheme load func tion, if needed . 2.1. Starting the D ual P rocess Build The dual pr ocess build allo ws you t o run C ortex on y our lo cal machine (host) and F luen t on a r emot e machine .The ad vantage of using the dual pr ocess build is fast er response t o gr aphics ac tions (such as zoom-in, zoom-out , opening a dialo g box, and so on) when y ou use F luen t remot ely. If the net work connec tivit y is slo w, then gr aphics ac tions ma y app ear slo w and jer ky. By controlling the gr aphics ac tions locally, the slo w response of the gr aphics ac tions c an b e avoided . For e xample , if y ou ar e handling a big mesh (such as the under hood mesh), you c an star t a dual pr ocess build t o run F luen t remot ely with only the displa y set t o your lo cal machine . To star t the dual pr ocess build of F luen t in meshing mo de, do the f ollowing: 1. Start Fluen t on y our lo cal machine using the c ommand fluent -serv -meshing . 71Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.The F luen t windo w will app ear with the v ersion pr ompt in the c onsole . 2. Type listen and pr ess Enter. You will b e pr ompt ed f or a timeout (the p eriod of time t o wait f or a c onnec tion fr om r emot e Fluen t). The default v alue is 300 sec onds .You c an also sp ecify the timeout v alue based on y our r equir emen t. Utilize this time t o lo g in to the r emot e machine and t o star t Fluen t. 3. Press Enter again. A message will pr ompt y ou t o star t Fluen t on the r emot e machine with the f ollowing ar gumen ts: -cx host:p1:p2 wher e, host is the name of the host (lo cal) machine on which C ortex is r unning . p1 and p2 are the t wo in tegers indic ating the c onnec ting p ort numb ers tha t are used t o commu- nicate inf ormation b etween C ortex on the host machine and F luen t on the r emot e machine . 4. Login t o the r emot e machine and set the displa y to the host machine . 5. Start Fluen t from the r emot e machine using the f ollowing c ommand:fluent 3d -cx host:p1:p2 The host and p ort numb ers ar e displa yed in the message windo w. Note The user in terface commands r elated t o the File menu (such as r eading files , imp orting files) and other Selec t File dialo g boxes do not w ork for the dual pr ocess build .You need t o use the TUI c ommands inst ead (f or e xample ,/file/read-mesh ). Imp ortant •The host c annot b e detached and r eattached; onc e the c onnec tion is br oken the da ta is lost. You need t o sa ve the da ta if the machine needs t o be shut do wn in b etween. •All gr aphics inf ormation will b e sen t over the net work, so initially it c ould tak e a long time t o assemble gr aphic al inf ormation (esp ecially if the host and r emot e ser ver ar e acr oss c ontinen ts) but af ter tha t the gr aphics manipula tion is fast. 2.2. Dynamic ally S pawning P rocesses B etween F luen t Meshing and F luen t Solution M odes For par allel simula tions star ted in meshing mo de with mor e than one pr ocess, the F luen t session will be star ted b y using the numb er of pr ocesses r equest ed f or meshing .When swit ching t o solution mo de, Fluen t will aut oma tically spa wn the r emaining par allel no de pr ocesses needed t o achie ve the r equest ed numb er of t otal solution pr ocesses . Even though aut oma tic spa wning is used b y default a t star t up f or runs using mor e than one pr ocess, you c an alw ays change the numb er of additional pr ocesses t o be Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 72Starting F luen t in M eshing M odespawned b efore swit ching t o solution mo de using the /parallel/spawn-solver-process text user in terface (TUI) c ommand . This t ext command pr ompts y ou f or: •Total numb er of desir ed pr ocesses (must b e gr eater than or equal t o the numb er of meshing pr ocesses). Fluen t will spa wn additional pr ocesses as nec essar y. •(Linux and mix ed Windo ws / Linux) In terconnec t type to be used f or the distr ibut ed par allel simula tion. You can cho ose fr om infiniband ,ethernet ,shared memory , or y ou c an r etain the default v alue . •Machine list or host file . If you decide t o run in par allel using mor e than one machine , then y ou should provide the machine list or host file , other wise , you c an sk ip this option b y pr essing Enter. •(Linux and mix ed Windo ws / Linux) Option t o use ssh for distr ibut ed simula tions , other wise , you c an sk ip this option b y pr essing Enter to retain the default option. Imp ortant Note the f ollowing: •Dynamic pr ocess spa wning is not supp orted on C ray systems .You c an k eep the same numb er of c ores for meshing mo de as f or solv er mo de, however, you should c ontinue the solv er it erations using another separ ate solv er session. •Dynamic pr ocess spa wning is only supp orted with the f ollowing MPI s: –default –ibmmpi •While r unning under the F luen t–supp orted load managers (f or e xample , SGE/LSF/PBS Pro), the t otal numb er of r equir ed par allel no de pr ocesses must b e request ed a t the start of F luen t session, and F luen t will initially star t with the sp ecified numb er of processes f or meshing mo de and will aut oma tically spa wn the r emaining no de pr o- cesses while swit ching t o solution mo de. •Using a single machine host file with diff erent numb ers of meshing and solv er cores a t the start of an ANSY S Fluen t session ma y result in an unin tended host allo cation. Inst ead, you should sp ecify a machine host file only f or the initial (meshing) mo de.Then b efore swit ching from the meshing t o the solution mo de, you should use the parallel/spawn-solver- processes text command t o request additional c ores and sp ecify a separ ate machine host file f or the additional c ores. 73Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dynamic ally S pawning P rocesses B etween F luen t Meshing and F luen t Solution M odesRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 74Chapt er 3: Graphic al U ser In terface The gr aphic al user in terface (GUI) c omp onen ts ar e illustr ated in Figur e 3.1: The U ser In terface Comp on- ents (p.75).The in terface will change dep ending on whether y ou ar e in meshing mo de (as descr ibed in this guide) or solution mo de (as descr ibed in the Fluen t User's G uide (p.1)). For details on swit ching between the meshing and solution mo de, see Solution (p.76). Figur e 3.1: The U ser In terface Comp onen ts Objec t-based meshing is a c ontext-driven, visual w orkflow, acc essible using the major in terface com- ponen ts. A c omplet e descr iption of the c omp onen ts is f ound in the User In terface Comp onen ts (p.76) section. Menu bar c ommands ar e appr opriate for z one-based meshing or ad vanced displa y and r eport options . Full descr iptions of the menu c ommands ar e in their r elated chapt ers in this manual. Some of the user in terface elemen ts can b e mo ved or tabb ed t ogether t o suit y our pr eferences.You can also mo dify a ttribut es of the in terface (including c olors and t ext fonts) t o better ma tch y our pla tform environmen t.These ar e descr ibed in Customizing the U ser In terface (p.95). 75Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.The help butt on ( ) acc esses a dr op do wn list f or quick acc ess t o the in tegrated help sy stem, including the F luen t User's G uide .The F luen t integrated help sy stem is descr ibed in detail in Using the H elp S ys- tem (p.96). 3.1. User In terface Comp onen ts The c omp onen ts ar e descr ibed in detail in the subsequen t sec tions . 3.1.1. The R ibbon 3.1.2. The Workflow Tab 3.1.3. The Outline View Tab 3.1.4. The G raphics Windo w 3.1.5. Quick S earch 3.1.6. The C onsole 3.1.7. The Toolbars 3.1.8. ACT S tart Page 3.1.1. The R ibbon In Mesh G ener ation mo de, the r ibbon c ontains options t o help with managing the gr aphic al displa y, selec ting objec ts or z ones , and pa tching options . Note When w orking with C AD A ssemblies , certain meshing r ibbon t ools ar e disabled . The hide r ibbon butt on ( ) is used t o minimiz e the r ibbon, allo wing mor e ar ea for the gr aphics windo w. Click a sec ond time t o maximiz e the r ibbon t o restore the gr aphics windo w ar ea. Solution The Switch t o Solution option enables y ou t o swit ch fr om meshing mo de t o solution mo de. It transf ers all of the v olume mesh da ta fr om meshing mo de t o solution mo de in ANSY S Fluen t. You will b e ask ed t o confir m the mesh is v alid and tha t you w ant to swit ch t o solution mo de. Imp ortant •Only v olume meshes c an b e transf erred t o solution mo de; surface meshes c annot b e transf erred. Face zones which ar e not c onnec ted t o volume mesh (geometr y objec ts or un- referenced z ones in c ase of mesh objec t-based w orkflow) will b e transf erred as imp orted sur faces when the v olume mesh is tr ansf erred fr om meshing t o solution mode. Also, any unmeshed fac e zones c onnec ted t o volume mesh (mesh objec t with some r egions filled or unr eferenced z ones), will b e disc onnec ted and transf erred as imp orted sur faces in solution mo de. •You should check tha t the mesh qualit y is adequa te before transf erring the mesh da ta to solution mo de. See Check ing the M esh (p.469) and Check ing the M esh Q ualit y (p.472) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 76Graphic al User In terfacefor details .When y ou ar e sa tisfied with the qualit y of the gener ated mesh, you c an proceed t o solution mo de. •Hanging-no de meshes ar e converted t o polyhedr a dur ing mesh tr ansf er. Imp ortant In objec t-based w orkflows, mer ging c ell z ones r equir es tha t the y be in the same volumetr ic region. To mer ge c ell z ones tha t cannot b e in the same v olumetr ic region b ecause the y are not c ontiguous , you will need t o first delet e the objec t(s) only , and then use the Manage C ell Z ones dialo g box. Note •The c ommand switch-to-solution-mode corresponds t o the Switch t o Solution butt on. •You c annot swit ch back fr om solution mo de t o meshing mo de af ter the mesh da ta has been tr ansf erred. However, if no file has b een r ead in solution mo de, you c an use the c ommand switch-to-meshing-mode to swit ch t o meshing mo de t o gener ate a mesh to be transf erred, if y ou desir e. •The meshing and solution mo des in F luen t ha ve diff erent options a vailable f or some user c onfigur ation settings .Thus, these c onfigur ation settings ma y be changed when swit ching fr om meshing t o solution mo de and ma y not b e the same when r etur ning to one mo de af ter using the other . Bounds Use the Bounds group t o limit the displa y region based on pr oximit y to a selec ted en tity in y our model. •Selec tion is used t o sp ecify the en tity on which the B ounds ar e centered. You c an set a selec tion filt er and then click t o selec t the en tity in the gr aphics windo w. •Set symmetr ical upp er and lo wer distanc e limits in the +/- D elta text box. Limit the b ounds dir ectionally with the X-, Y-, and Z-R ange check boxes. •Use Set R anges to apply the displa y limits .Reset disables the b ounds displa y.You will ha ve to redraw to see the eff ect. •If Cutplanes is check ed, the displa y region is link ed t o the B ounds tab in the Displa y Grid dialo g box.You ma y inser t up t o six cutplanes (t wo in each of the x-, y-, and z-dir ection) and asymmetr ically control their lo cation. See Gener ating the M esh D ispla y Using the D ispla y Grid D ialog Box (p.476). 77Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User In terface Comp onen tsClipping P lanes Crops the displa y region along the c oordina te sy stem ax es when Inser t Clipping P lanes is enabled . The slider allo ws interactive position of the clipping plane . Use the Flip check box to reverse the dir ection of the clipping plane . Use the Show C ut E dges option t o displa y the cut edges of the mo del e xposed b y the clipping plane .This option is disabled b y default. Use the Draw C ell L ayer check box to visualiz e a la yer of c ells of the v olume mesh on the clipping plane .This option is disabled b y default. Onc e the Draw C ell L ayer option is enabled , use the Freeze Cell L ayer check box to keep the displa yed la yer of c ells in plac e while y ou perform additional mesh displa y op erations . To dr aw a la yer of c ells on the clipping plane f or sp ecific c ell z ones , selec t the c ell z one(s) under M esh O bjec ts in the Tree and use the Draw C ell L ayer option in the c ontext menu . Selec tion H elper Use the Selec tion H elper group t o assist in selec ting fac e zones , edge z ones , objec ts, objec t fac e zones , or objec t edge z ones b y a Name P attern and Geometr y Rec overy level. Selec t the t ype of zone or objec t using the Filter drop do wn list , then use the Name P attern field t o refine y our selec- tion. When selec ting Face Zones in the Filter list, the Geometr y Rec overy option is a vailable t o further r efine y our selec tion. The Advanc ed... butt on op ens the Zone S elec tion H elper dialo g box. Use this dialo g box to expand the z one selec tion cr iteria to include the numb er of en tities pr esen t in them, or using the minimum or maximum fac e zone ar ea. The Selec tion H elper options and the Zone S elec tion H elper dialo g box ma y be used with all dialo g boxes tha t contain z one or objec t lists (f or e xample ,Cell Z ones and Boundar y Zones dialo g boxes). Mouse P robe Func tion Use the Mouse P robe Func tion group t o set the b ehavior of the mouse pr obe butt on. Selec t enables the selec tion of a single en tity based on the filt er selec ted and also adds the selec ted entity to a list tha t can b e used in most dialo g boxes. Box enables the selec tion of a gr oup of en tities within a b ox.To define the selec tion b ox, click the mouse pr obe butt on a t one c orner of the r egion t o be selec ted, drag the mouse t o the opp osite corner, and r elease the mouse pr obe butt on. Polygon enables the selec tion of a gr oup of en tities within a p olygonal r egion. To define the selec tion polygon, click the mouse pr obe butt on a t one v ertex of the p olygonal r egion t o be selec ted, and use the lef t mouse butt on t o succ essiv ely selec t each of the r emaining v ertices. Click the mouse pr obe butt on again (an ywher e in the gr aphics windo w) t o complet e the polygon definition. Selec t Visible E ntities enables selec tion of only visible en tities (no des, faces, zones , objec ts) when the mouse pr obe func tion is set t o Box or Polygon .The selec tion includes only en tities visible t o the e ye, and not Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 78Graphic al User In terfacethose hidden b ehind other en tities in the displa y.This option is disabled b y default. When enabled , ensur e tha t the mo del is z oomed t o an appr opriate level for correct selec tion. Note •If the mesh is not c onnec ted, all en tities (no des, faces, zones , objec ts) will b e selec ted irrespective of whether the y are visible or not. •This visual selec tion b ehavior w orks only on lo cal displa ys and ma y gener ate warning messages when a ttempting selec tion on a r emot e sy stem. Note For additional mouse pr obe func tion options , see Controlling the M ouse P robe Function (p.488) Displa y contains options t o control the displa y in the gr aphics windo w. All Faces enable or disable the displa y of all fac es in the visible z ones or objec ts, color ed b y their z one type. Free F aces enable or disable the displa y and highligh ting of fr ee fac es on the visible z ones or objec ts. A fr ee face is one ha ving a t least one edge not shar ed with a neighb oring fac e. Multi F aces enable or disable the displa y of multi-c onnec ted fac es on the visible z ones or objec ts, along with their no des. A multi-c onnec ted fac e is a b oundar y fac e tha t shar es an edge with mor e than one other fac e, while a multi-c onnec ted no de is a no de tha t is on a multi-c onnec ted edge (tha t is, an edge tha t is shar ed b y mor e than t wo boundar y fac es). Face Edges enable or disable the displa y of fac e edges in the visible z ones or objec ts.This option w orks in conjunc tion with the All Faces option. Title enable or disable the displa y of the c aption blo ck ar ea b elow the gr aphic c ontaining da te, produc t, and c ontents of the displa y. Help Text enable or disable the displa y of help t ext for tool butt ons or hot-k eys. Detailed help is displa yed whene ver a c ommand is selec ted b y click ing a butt on (or pr essing a hotk ey on the k eyboard), and r emains visible un til the c ommand is c omplet e or another c ommand selec ted. Highligh t enable or disable the highligh ting of objec ts, face zone lab els, volumetr ic regions , or c ell z ones selec ted in the tr ee. Edge Z ones enable or disable the displa y of edge z ones c ompr ising the objec ts dr awn in the gr aphics windo w. 79Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User In terface Comp onen tsTranspar enc y toggle the tr anspar ency of the selec ted objec ts/zones dep ending on the mo de of selec tion set. If no objec t/zone is selec ted then the en tire geometr y is made tr anspar ent so tha t internal ob- jects/zones ar e visible . Explo de toggle b etween a nor mal view and an e xplo ded view of the objec ts in the geometr y. Edge Z one S elec tion M ode enable or disable the edge z one selec tion mo de.This r estricts selec tion t o edge z ones en tities only . Edges show or hide edges on selec ted z ones and objec ts indep enden t of the mo de of selec tion. If no objec t/zone is selec ted, then the edges on the displa yed z ones/objec ts ar e sho wn/hidden. Examine contains options f or obtaining additional inf ormation ab out the selec ted en tities . Centroid prints the c oordina tes of the c entroid of the selec ted fac e to the c onsole . This also w orks for edges and no des. Distanc e calcula tes and displa ys the distanc e between t wo selec ted lo cations or no des. Entity Inf ormation prints detailed inf ormation ab out the selec ted en tities in the message windo w. For mor e details , see Entity Inf ormation (p.537). In addition, if a selec ted z one or objec t has b een set as a target, this will t oggle the iden tifying c olor . Patch Options contains additional options applic able t o the pa tching t ools. Remesh enables aut oma tic r emeshing of the pa tched ar ea. Separ ate enables y ou t o create a separ ate fac e zone/objec t for the new fac es cr eated. Additional options for objec t/zone gr anular ity and t ype are available in the Patch Options dialo g box (see Using the P atch Options D ialog Box (p.243) for details). The Remesh and Separ ate options ar e enabled b y default. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 80Graphic al User In terface3.1.2. The Workflo w Tab Use the Workflo w tab t o acc ess guided w orkflow templa tes tha t can b e used t o str eamline the use of F luen t in meshing mo de. Common tasks and pr operty settings ar e available t o walk y ou thr ough the pr ocess of gener ating a v olume mesh f or use in the F luen t solv er. For instanc e, the Watertigh t Geometr y guided w orkflow can b e used t o quick ly gener ate a v olume mesh fr om an imp orted w atertigh t CAD geometr y.You c an also cr eate your o wn w orkflow using the a vailable tasks (such as , adding lo cal sizing c ontrols, creating a sur face mesh, capping inlets and outlets , creating r egions , and so on). See Working With F luen t Guided Workflows (p.123) for mor e inf ormation. Figur e 3.2: The Watertigh t Geometr y Workflo w 3.1.3. The Outline View Tab In Mesh G ener ation mo de, you use the Outline View tr ee f or objec t-focused managemen t of the meshing w orkflow and displa y. Branches c an b e expanded and c ollapsed as r equir ed. At each le vel, right-click and selec t from c ontext-sensitiv e menus t o manage the mesh gener ation pr ocess. 81Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User In terface Comp onen tsFigur e 3.3: The Outline View Tree Figur e 3.4: Model L evel M enu At the t op of the tr ee, right-click Model to acc ess c ontrols not sp ecific t o an y en tity. For e xample , you can acc ess dialo g boxes to cr eate new c onstr uction geometr y or objec ts; set mesh siz e par amet ers; and manage ma terial p oints, periodicit y, and user-defined gr oups .You c an also pr epar e the mesh f or solving in solution mo de. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 82Graphic al User In terfaceFigur e 3.5: CAD A ssemblies Tree The CAD A ssemblies tree is cr eated when the Create CAD A ssemblies option is selec ted f or C AD imp ort. It represen ts the C AD tr ee as it is pr esen ted in the C AD pack age in which it w as cr eated.The CAD en tities in the tr ee ar e categor ized as c omp onen ts and b odies . Comp onen ts represen t an assembly , sub-assembly , or par t in the or iginal C AD pack age, while b odies ar e the basic en tities which include CAD z ones .You c an also set up lab els f or the C AD z ones , if requir ed. Figur e 3.6: CAD A ssemblies M enu Right-click CAD A ssemblies to dr aw or delet e all imp orted assemblies , and obtain the r eferenced FMDB file lo cations .The Tree sub-menu c ontains options tha t control the app earance of the C AD A s- semblies tr ee.These options c an b e used t o selec t or deselec t the C AD objec ts and z ones in the tr ee, expand or c ollapse the tr ee br anches , and also delet e suppr essed or lo cked C AD objec ts. 83Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User In terface Comp onen tsFigur e 3.7: CAD C omp onen t/Body Level M enu The tr ee menus a t CAD c omp onen t and b ody levels c ontain displa y options and options f or up dating the C AD en tities , creating and manipula ting geometr y/mesh objec ts, setting the sta te and mo difying the C AD en tities , and tr ee selec tion options . Figur e 3.8: CAD L abel L evel M enu The C AD lab el menu c ontains options f or deleting and r enaming the lab els. For a full descr iption of the C AD A ssemblies tr ee menus , see CAD A ssemblies (p.199). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 84Graphic al User In terfaceGeometr y and Mesh O bjec ts When r eading a mesh file , the tr ee is p opula ted with Geometr y O bjec ts and Mesh O bjec ts, if alr eady defined . Imp orting a mesh fr om other f ormats will r esult in the edge z ones , boundar y fac e zones , and cell z ones a vailable in the Unreferenc ed branch. These z ones ar e not included in an y objec t. Geometr y objec ts ar e created when C AD files ar e imp orted using the CAD F aceting option. The geo- metr y objec ts ma y be non-c onformal. Mesh objec ts ar e created when C AD files ar e imp orted using the CFD S urface M esh option. The mesh objec ts ar e conformal. See Imp orting C AD F iles (p.112) for details on the C AD imp ort options . You c an also cr eate geometr y/mesh objec ts fr om the C AD en tities in the C AD A ssemblies tr ee. CAD entities ar e lo cked when c orresponding geometr y or mesh objec ts ar e created. See Creating and Modifying G eometr y/M esh O bjec ts (p.203) for details . Figur e 3.9: Global O bjec t Level M enu You use the Geometr y O bjec ts or Mesh O bjec ts context-sensitiv e menu t o perform ac tions on all objec ts in y our mo del. At the global objec t level, right-click ( Geometr y O bjec ts or Mesh O bjec ts) to draw or selec t all the objec ts. If the objec ts ar e asso ciated with C AD en tities , you c an also up date all or detach all objec ts. 85Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User In terface Comp onen tsFigur e 3.10: Individual O bjec t Level M enu Right-click ing on an individual Objec t (Geometr y or M esh) name in the Outline View op ens a c ontext- sensitiv e menu t o acc ess objec t level refinemen t and c ontrol tasks .You c an also selec t objec ts gr aph- ically, but the menus ar e available only when selec ting in the Outline View. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 86Graphic al User In terfaceFigur e 3.11: Face Zone L abels L evel M enu For geometr y objec ts,Face Zone L abels are gr oups of fac e zones c ompr ising the objec t. For mesh objec ts, these ar e or iginal C AD z ones or b odies , or fac e zones c ompr ising the mesh objec t. If the mesh objec t is cr eated b y mer ging multiple mesh objec ts, the fac e zone lab els r epresen t the objec ts tha t were mer ged .They pr ovide the link t o the or iginal geometr y. Under M esh O bjec ts,Face Zone L abels form b oundar ies enclosing the Volumetr ic Regions --separ ate, closed , water-tigh t volumes .Cell Z ones are regions of v olume mesh. The c ontext-sensitiv e menu f or Face Zone L abels contains options f or dr awing and selec ting all lab els, creating new lab els, and obtaining an o verall summar y or detailed inf ormation ab out the fac e zone labels. For geometr y objec ts, ther e ar e additional options t o remo ve lab els fr om z ones and options for displa ying and selec ting unlab eled z ones . For mesh objec ts, the Join/In tersec t... option c ontains options f or cr eating a c onformal sur face mesh. 87Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User In terface Comp onen tsFigur e 3.12: Individual L abel M enu Right-click ing on a Zone L abel name under geometr y/mesh objec ts allo ws for z one le vel displa y and selec tion options , and meshing tasks . Figur e 3.13: Unreferenc ed Z ones M enu The Unreferenc ed menu includes the c ommon Draw and List S elec tion menus as w ell as options t o manage the unr eferenced z ones . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 88Graphic al User In terfaceFor a full descr iption of objec t based meshing using the tr ee and c ontext menus , refer to Surface M esh Processes (p.239). Note Any dialo g box op ened via r ight-click ing in the Outline View b ecomes modal.That is, to preser ve the ac tive selec tion, the ac tion must b e complet ed or the dialo g box closed b efore the tr ee selec tion c an b e changed . 3.1.4. The G raphics Windo w The gr aphics windo w displa ys the cur rent sta te of y our mo del acc ording t o your selec ted Render ing, Color Scheme and Displa y options . See Controlling D ispla y Options (p.480) for details . The hide r ibbon butt on ( ) is used t o expand the ar ea for the gr aphics windo w b y minimizing the ribbon. Click a sec ond time t o maximiz e the r ibbon t o restore the gr aphics windo w ar ea. The axis tr iad indic ates the or ientation of the mo del and also pr ovides options f or manipula ting the orientation in the gr aphics windo w. To change the or ientation of the mo del using the tr iad, you c an: •Click an axis/semi-spher e to or ient the mo del in the p ositiv e/nega tive dir ection. •Right-click an axis/semi-spher e to or ient the mo del in the nega tive/positiv e dir ection. •Click the c yan iso-ball t o set the isometr ic view . •Click the whit e rotational ar rows to perform in-plane clo ckwise or c oun terclockwise 90 degr ee rotations . •Left-click and hold--in the vicinit y of the tr iad--and use the mouse t o perform fr ee rotations in an y dir ection. Release the lef t mouse butt on t o stop r otating . You c an cho ose ho w the mouse butt ons in teract with the gr aphics displa y using the Mouse Butt ons dialo g box. See Controlling the M ouse B uttons (p.487). 3.1.5. Quick S earch The sear ch bar (upp er right of the F luen t windo w) allo ws you t o quick ly lo cate the c ommands or controls tha t you ar e lo oking f or. Clicking the sear ch r esults is equiv alen t to click ing the same c ontrol in the r ibbon. Hovering o ver a sear ch r esult highligh ts the lo cation of the c ontrol in the r ibbon. Clicking a text command sear ch r esult aut oma tically en ters the t ext of the c ommand , but it do es not e xecut e the c ommand; you still ha ve to pr ess En ter in the c onsole t o execut e the t ext command . 89Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User In terface Comp onen ts3.1.6. The C onsole The c onsole is usually lo cated b elow the G raphics Windo w, as sho wn in Figur e 3.1: The U ser In terface Comp onen ts (p.75). It is used t o pr ovide a t ext based in terface to Fluen t meshing . •The c onsole will displa y messages r elating t o meshing or solution pr ocedur es. All console inf ormation is sa ved t o memor y, so y ou c an r eview it a t an ytime b y using the scr oll bar on the r ight side of the console .The c onsole visually indic ates whether the t ext is an er ror message (r ed), user input (blue), or pr ogram gener ated output (black). •The c onsole b ehaves lik e an "x term" or other Linux c ommand shell t ool, or t o the MS-DOS C ommand Prompt windo w. It enables y ou t o interact with the TUI menu . For mor e inf ormation on the TUI, see Text User In terface in the Fluent Text Command List . •You ma y interrupt the pr ogram b y issuing a "br eak" c ommand (pr ess Ctrl+C) while da ta is b eing pr o- cessed .You c annot c ancel an op eration af ter it is c omplet e and the pr ogram has star ted dr awing in the gr aphics windo w. •You ma y perform text copy and past e op erations b etween the c onsole and other X Windo w (or Win- dows) applic ations tha t supp ort copy and past e. Note On a Linux sy stem, follow the st eps b elow to copy text to the clipb oard: 1.Drag the p ointer acr oss the t ext to be copied . 2.Move the p ointer to the tar get windo w. 3.Press the middle mouse butt on t o “past e” the t ext. The Auto-scr oll check b ox enables aut oma tic scr olling of the c onsole when new c ontent is pr inted. When the Auto-scr oll is disabled , the cursor sta ys at the last selec ted p osition. Messages will c ontinue to be app ended in the c onsole , but the cursor will not aut oma tically scr oll t o the b ottom un til the Auto-scr oll is enabled . 3.1.7. The Toolbars The user in terface includes se veral toolbars t o pr ovide shor tcuts t o performing c ommon tasks .You can enable or disable the visibilit y of the t oolbars tha t app ear in the gr aphic al user in terface.You c an dock the t oolbars ar ound the gr aphics windo w or p osition them "floa ting" a t an y convenien t location in the user in terface. The Standar d Toolbar contains options t o control the la yout and t o find additional r esour ces. •Click the ANSY S logo t o op en the ANSY S home page in y our default br owser. •Use the options in the Arrange the w orkspac e ( ) menu t o control the applic ation windo w la yout. You can also enable or disable the visibilit y of each in terface comp onen t in this menu . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 90Graphic al User In terfaceThe most r ecent arrangemen t of the user in terface comp onen ts will b e sa ved t o a .cxlayout file in your home f older .The la yout will b e restored the ne xt time ANSY S Fluen t is op ened . Note Do not use multiple gr aphics windo ws in meshing mo de. •Help ( ) contains options f or acc essing the U ser D ocumen tation and obtaining lic ense usage and pr oduc t version inf ormation. See Using the H elp S ystem (p.96) for details . On each side of the gr aphics windo w ar e context-sensitiv e toolbars f or quick acc ess t o commonly used operations . Right-click an y toolbar t o acc ess the Toolbar Options to set the visibilit y of the r espective toolbars . 3.1.7.1. Point er Tools You c an quick ly change the r ole of the lef t mouse butt on using the options in the Pointer Tools toolbar . See Controlling the M ouse B uttons (p.487) for a descr iption of the options . 91Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User In terface Comp onen ts•Rota te View assigns the mouse-r otate func tion t o the lef t mouse butt on. •Pan assigns the mouse-dolly func tion t o the lef t mouse butt on. •Zoom In/Out assigns the mouse-r oll-z oom func tion t o the lef t mouse butt on. •Zoom t o Area assigns the mouse-z oom func tion t o the lef t mouse butt on. 3.1.7.2. View Tools You c an quick ly change the mo del displa y using the View Tools toolbar . •Fit to Windo w adjusts the o verall siz e of y our mo del t o tak e maximum ad vantage of the gr aphics windo w’s width and heigh t. •Last View restores the displa y to the pr evious view . •Set vie w contains a dr op-do wn of view s, allo wing y ou t o displa y the mo del in isometr ic or one of six or thographic view s. You c an also click on the displa y ax es tr iad in the gr aphics windo w to change t o one of the standar d view s. Use the r ight mouse butt on t o reverse the or thographic view . •Save Picture captur es an image of the ac tive gr aphics windo w. For mor e inf ormation, see Saving Picture Files (p.119). 3.1.7.3. Projec tion Use the Projec tion toolbar t o cho ose t o displa y a p ersp ective view of the gr aphics (default) or an orthographic view . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 92Graphic al User In terfaceWhen the or thographic view is enabled , the r uler is enabled in the gr aphics windo w. 3.1.7.4. Displa y O ptions This t oolbar is applic able only in solution mo de. See Mesh D ispla y Configur ation (p.559) for details . 3.1.7.5. Additional D ispla y O ptions There ar e additional displa y options a vailable when w orking in the gr aphics windo w: •Ruler turns the r uler on and off (and swit ches the view t o or thographic). •Grid D ispla y opens the Displa y Grid dialo g wher e you c an selec t options f or displa ying the mesh. See Gener ating the M esh D ispla y Using the D ispla y Grid D ialog Box (p.476) for mor e inf ormation. •Front Faces Transpar ent mak es the fr ont fac es of the displa yed objec t transpar ent, allo wing y ou t o see inside . •Axes Visibilit y turns the ax es displa y on and off . •Titles Visibilit y turns the titles on and off . 3.1.7.6. Filter Toolbar Use the Filter toolbar t o set the en tity type tha t the mouse pr obe filt er will r ecogniz e. See Controlling the M ouse P robe Function (p.488). 93Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User In terface Comp onen tsThe selec tion filt ers a vailable in the t oolbar ar e Position ,Node,Edge ,Zone , and Objec t.You c an also set the mouse pr obe to Draw S izes and e xamine the mesh siz e at the pr obe point. The t oolbar also c ontains options f or selec ting visible en tities based on the filt er set , deselec ting the last en tity, and clear ing all selec tions . 3.1.7.7. CAD Tools Use the CAD Toolbar to acc ess t ools f or manipula ting C AD en tities and cr eating/managing lab els and geometr y/mesh objec ts asso ciated with the C AD en tities .This t oolbar is a vailable only when the CAD en tities ar e displa yed in the gr aphics windo w. See CAD A ssemblies (p.199) for details . 3.1.7.8. Tools Use the Tools toolbar t o acc ess options f or c onstr ucting geometr y pr imitiv es or lo op selec tion t ools. You c an also use the Isola te tools t o isola te selec ted z ones/objec ts in the displa y or limit the displa y to zones/objec ts based on ar ea/cur vature of the selec ted z ones/objec ts. 3.1.7.9. Cont ext Toolbar Use the Context toolbar t o see c ontext-sensitiv e options based on the en tities selec ted.When en tities are selec ted with the mouse pr obe, this t oolbar changes t o represen t the tasks and pr ocesses applic able to the selec ted en tities , as a subset of all tasks and pr ocesses used t o gener ate a mesh. An example is sho wn b elow. Descr iptions of a vailable t ools ar e compiled in Shortcut Ke y Actions (p.527). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 94Graphic al User In terface3.1.8. ACT S tart Page The ACT S tart Page is a vailable when A CT func tionalit y is enabled in F luen t.To enable A CT func tion- ality, use one of these options: •Enable Load A CT in the F luen t Launcher . •Selec t ACT from the Arrange the w orkspac e ( ) menu . •Use the c ommand:/file/load-act-tool . The ACT S tart Page provides an acc ess p oint for ANSY S ACT func tionalit y in F luen t. From this page , you c an acc ess t ools tha t can b e used in the de velopmen t and e xecution of e xtensions . For mor e in- formation, see ACT Tools in the ANSY S ACT D evelop er's G uide . For inf ormation on cr eating tar get pr oduc t wizar ds for F luen t, see the ACT C ustomization G uide f or Fluent . 3.2. Customizing the U ser In terface You ma y want to cust omiz e the gr aphic al user in terface by changing the w ay tha t the v arious elemen ts are ar ranged .This c an b e achie ved b y "dr agging" elemen ts and "dr opping" them a t a new lo cation. For example , the gr aphics windo w can b e tabb ed on t op of the c onsole , or the c onsole c an b e mo ved b elow the tr ee. In meshing mo de, you c an mo ve the c onsole and the t oolbars . To restore items tha t you in tentionally or unin tentionally closed , right-click the t op t oolbar t o restore those it ems .You c an also click to selec t one of the pr edefined la youts and r estore missing it ems . You ma y also w ant to cust omiz e the gr aphic al user in terface by changing a ttribut es such as t ext color , back ground c olor , and t ext fonts.The pr ogram will tr y to pr ovide default t ext fonts tha t are sa tisfac tory for y our pla tform's displa y siz e, but in some c ases cust omiza tion ma y be nec essar y if the default t ext fonts mak e the GUI t oo small or t oo lar ge on y our displa y, or if the default c olors ar e undesir able . The GUI in F luen t is based on the Qt Toolkit. If you ar e unfamiliar with the Qt Toolkit, refer to an y documen tation y ou ma y ha ve tha t descr ibes ho w to use the Qt Toolkit or applic ation. The gr aphic al attribut es c an b e mo dified in a Qt st ylesheet file named cxdisplay.qss and plac ed in y our home directory. 3.3. Setting U ser P referenc es/Options You c an sp ecify global settings tha t are applied whene ver y ou ar e op erating in ANSY S Fluen t.These settings ar e case-indep enden t and ar e controlled using the Preferenc es dialo g box. To review and mo dify y our pr eferences, open the Preferenc es dialo g box by selec ting Preferenc es... from the File menu . File → Preferenc es... 95Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U ser P references/OptionsFigur e 3.14: Preferenc es D ialo g Box Note •Some settings , such as r uler visibilit y and mouse-butt on c ontrols, can also b e controlled lo cally within a F luen t session (tha t is, outside of the Preferenc es dialo g box). Settings tha t de viate from the global settings sp ecified in the Preferenc es dialo g box will not b e retained b eyond the cur rent session. 3.4. Using the H elp S ystem Fluen t includes an in tegrated help sy stem tha t provides an easy acc ess t o the do cumen tation. Using the gr aphic al user in terface, you c an acc ess the en tire User's G uide and other do cumen tation. The U ser's Guide and other manuals ar e displa yed in the ANSY S Help, which enables y ou t o use the h ypertext links and the br owser's sear ch and na viga tion t ools t o find the inf ormation y ou need . There ar e man y ways to acc ess the inf ormation c ontained in the online help: •You c an get r eference inf ormation fr om the main windo w or an y dialo g box by click ing Help. •You c an r equest c ontext-sensitiv e help f or a par ticular menu it em or dialo g box by selec ting Help → Context- Sensitiv e Help. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 96Graphic al User In terfaceWith the r esulting question-mar k cursor , selec t an it em fr om a pull-do wn menu t o op en the ANSY S Help a t the selec ted it em. •You c an go t o the c ontents page f or the M eshing sec tion of the U ser's G uide and use the h ypertext links ther e to find the inf ormation y ou ar e looking f or. Selec t Help → User's G uide C ontents. 3.4.1. Help f or Text Interface Commands To find inf ormation ab out t ext interface commands , you c an either go t o the M eshing sec tion of the Fluen t Text Command List in the ANSY S Help, or use the t ext interface help sy stem descr ibed in Text User In terface in the Fluent Text Command List . 3.4.2. Obtaining a Listing of O ther Lic ense U sers If you ar e running with an e xisting F luen t license (F luen tLM), you c an obtain a listing of cur rent Fluen t users in the c onsole b y selec ting Help → License U sage . If your installa tion of F luen t is managed b y the ANSY S Lic ense M anager (ANSLIC_ADMIN), you will see a message tha t will indic ate tha t licensing is managed b y ANSLIC_ADMIN. For additional inf ormation on lic ensing inf ormation, refer to the Installa tion and Lic ensing D ocumen tation in the ANSY S Help. This inf ormation c an b e found b y doing the f ollowing in the help view er: 1.Scroll do wn t o the Installa tion and Lic ensing D ocumen tation item in the lef t pane of the view er. 2.Expand this do cumen t by click ing on the ic on t o the lef t of the do cumen t title . 3.Use the h yperlinks in the main view er windo w to find the desir ed inf ormation, or, expand the it ems in the lef t pane of the view er and scr oll t o the t opic of in terest. 97Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the H elp S ystemRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 98Chapt er 4: Text User In terface The t ext user in terface (TUI) in F luen t, also r eferred t o as The C onsole (p.560), is wr itten in a dialec t of Lisp c alled Scheme . Users familiar with Scheme will b e able t o use the in terpretive capabilities of the interface to cr eate cust omiz ed c ommands .The t ext-based menu sy stem pr ovides a hier archic al in terface to the under lying pr ocedur al in terface of the pr ogram. •You c an easily manipula te its op eration with standar d text-based t ools—input c an b e sa ved in files , modified using t ext edit ors, and r ead back in t o be execut ed. •The t ext menu sy stem is tigh tly in tegrated with the Scheme e xtension language , so it c an easily b e programmed t o pr ovide sophistic ated c ontrol and cust omiz ed func tionalit y. A mor e complet e descr iption of the t ext-based in terface, including a full list of c ommands is a vailable in Fluen t Text Command List . 99Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 100Chapt er 5: Reading and Writing F iles During a F luen t session, you ma y need t o: •Read mesh, case, CAD, jour nal, Scheme , domain, and siz e-field files . •Write mesh, case, jour nal, transcr ipt, and domain files . •Save pic tures of gr aphics windo ws. These files and op erations ar e descr ibed in the f ollowing sec tions . 5.1. Shortcuts f or R eading and Writing F iles 5.2. Mesh F iles 5.3. Case F iles 5.4. Reading and Writing S ize-Field F iles 5.5. Reading Scheme S ource Files 5.6. Creating and R eading J ournal F iles 5.7. Creating Transcr ipt F iles 5.8. Reading and Writing D omain F iles 5.9. Imp orting F iles 5.10. Saving P icture Files 5.1. Shor tcuts f or Reading and Writing F iles The f ollowing f eatures mak e reading and wr iting files c onvenien t: 5.1.1. Binar y Files 5.1.2. Reading and Writing C ompr essed F iles 5.1.3. Tilde Expansion (LINUX S ystems Only) 5.1.4. Disabling the O verwrite Confir mation P rompt 5.1.1. Binar y Files When y ou wr ite a mesh, case, or siz e-field file , a binar y file is sa ved b y default. Binar y files tak e up less memor y than t ext files and c an b e read and wr itten mor e quick ly by Fluen t. To sa ve a t ext file , disable the Write Binar y Files option in the Selec t File dialo g box when y ou ar e writing the file . 5.1.2. Reading and Writing C ompr essed F iles Fluen t enables y ou t o read and wr ite compr essed files . Use the Selec t File dialo g box to read or wr ite the files tha t ha ve been c ompr essed using compress or gzip . 5.1.2.1. Reading C ompr essed F iles 5.1.2.2. Writing C ompr essed F iles 101Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.5.1.2.1. Reading C ompr essed F iles If you selec t a c ompr essed file with a .z extension, Fluen t will aut oma tically in voke zcat to imp ort the file . If you selec t a c ompr essed file with a .gz extension, Fluen t will in voke gunzip to imp ort the file . For e xample , if y ou selec t a file named flow.msh.gz , the f ollowing message will b e reported, indic ating tha t the r esult of the gunzip is imp orted in to Fluen t via an op erating sy stem pip e. Reading "\" | gunzip -c \"Z:\flow.msh.gz\"\""... When r eading a c ompr essed file using the t ext interface, you only need t o en ter the file name . Fluen t first lo oks f or a file t o op en using just the input name . If it c annot find a file with tha t name , it a ttempts to lo cate files with default suffix es and e xtensions app ended t o the name . For e xample , if y ou en ter the name file-name , it tr averses the f ollowing list un til it finds an e xisting file t o op en: •file-name •file-name.gz •file-name.z •file-name.suffix •file-name.suffix.gz •file-name.suffix.z wher e suffix is a c ommon e xtension t o the file , such as .cas or .msh . Fluen t reports an er ror if it fails t o find an e xisting file with one of these names . Note For Windo ws systems , only files tha t were compr essed with gzip (tha t is, files with a .gz extension) c an b e read. Files tha t were compr essed using compress cannot b e read in to Fluen t on a Windo ws machine . 5.1.2.2. Writing C ompr essed F iles You c an use the Selec t File dialo g box to wr ite a c ompr essed file b y app ending a .z or .gz extension onto the file name . For e xample , if y ou ar e pr ompt ed f or a file name and y ou en ter a file name with a .gz extension, a compr essed file will b e wr itten. For e xample , if y ou en ter flow.gz as the name for a mesh file , Fluen t reports the f ollowing message: Writing "| gzip -cfv > Z:\flow.msh.gz"... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 102Reading and Writing F ilesThe sta tus message indic ates tha t the mesh file inf ormation is b eing pip ed in to the gzip command , and tha t the output of the c ompr ession c ommand is b eing r edir ected t o the file with the sp ecified name . In this par ticular e xample , the .msh extension w as added aut oma tically. Note For Windo ws systems , compr ession c an b e performed only with gzip .That is, you c an write a c ompr essed file b y app ending .gz to the name , but app ending .z does not compr ess the file . 5.1.3. Tilde E xpansion (LINUX S ystems Only) On LINUX sy stems , if y ou sp ecify ~/ as the first t wo char acters of a file name , the ~ is e xpanded as your home dir ectory. Similar ly, you c an star t a file name with ~username/ , and the ~username is expanded t o the home dir ectory of “user name ”. If you sp ecify ~/file as the mesh file t o be wr itten, Fluen t saves the file file.msh in y our home dir ectory.You c an sp ecify a sub directory of y our home directory as w ell: if y ou en ter ~/examples/file.msh , Fluen t will sa ve the file file.msh in the examples sub directory. 5.1.4. Disabling the O verwrite Confir mation P rompt By default , if y ou ask ANSY S Fluen t to wr ite a file with the same name as an e xisting file in tha t folder , it will ask y ou t o confir m tha t it is “OK t o overwrite” the e xisting file . If you do not w ant ANSY S Fluen t to ask y ou f or c onfir mation b efore it o verwrites e xisting files , you c an en ter the file/confirm- overwrite? text command and answ er no. 5.2. Mesh F iles Mesh files ar e created using the mesh gener ators (ANSY S M eshing , the meshing mo de in F luen t, GAMBIT , GeoM esh, and P reBFC), or b y se veral thir d-par ty CAD pack ages . From the p oint of view of F luen t, a mesh file is a subset of a c ase file (descr ibed in Case F iles (p.106)).The mesh file includes a list of the node c oordina tes, connec tivit y inf ormation tha t tells ho w the no des ar e connec ted t o one another t o form fac es and c ells, and the z one t ypes and numb ers of all the fac es (f or e xample ,wall-1 ,pressur e- inlet-5 ,symmetr y-2).The mesh file do es not c ontain an y inf ormation on b oundar y conditions , flow paramet ers. For inf ormation ab out the f ormat of the C AD pack age files , see Appendix A: Imp orting Boundar y and Volume M eshes (p.505), and f or details on the mesh file f ormat for F luen t, see Ap- pendix B: Mesh F ile F ormat (p.511). Note You c an also use the File → Read → Case... menu it em t o read a mesh file (descr ibed in Case F iles (p.106)) because a mesh file is a subset of a c ase file . Imp ortant If the mesh inf ormation is c ontained in t wo or mor e separ ate files gener ated b y one of the CAD pack ages , you c an r ead them one-b y-one b y selec ting Append F ile(s) in the Selec t 103Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Mesh F ilesFile dialo g box.You c an also r ead them t ogether and assemble the c omplet e mesh in the meshing mo de. By default , Fluen t saves the mesh files with the suffix .msh .You need not t ype the suffix while sa ving the mesh file , it will b e added aut oma tically. When F luen t reads a mesh file , it first sear ches f or a file with the e xact name y ou t yped. If a file with that name is not f ound , it will sear ch f or a file with .msh app ended t o the name . 5.2.1. Reading M esh F iles To read a mesh, selec t File → Read → Mesh... to op en the Selec t File dialo g box and selec t the mesh file t o be read. You c an also use this option t o read a F luen t mesh file cr eated with GAMBIT , or t o read the mesh contained in a c ase file . Note Reading a c ase file as a mesh file will r esult in loss of b oundar y condition da ta as the mesh file do es not c ontain an y inf ormation on b oundar y conditions . Case files c ontaining p olyhedr al cells c an also b e read in the meshing mo de of F luen t.You c an displa y the p olyhedr al mesh, perform certain mesh manipula tion op erations , check the mesh qualit y, and so on. Imp ortant You c annot r ead meshes fr om solv ers tha t ha ve been adapt ed using hanging no des.To read one of these meshes in the meshing mo de in F luen t, coarsen the mesh within the solv er un til you ha ve recovered the or iginal unadapt ed gr id. The /file/read-options command enables y ou t o set the f ollowing options f or reading mesh files: •Enforce mesh t opology:This option is disabled b y default. Enabling this option will or ient the fac e zones consist ently when the mesh file is r ead. If nec essar y, the z ones b eing r ead will b e separ ated, such tha t each boundar y fac e zone has a t most t wo cell z ones as neighb ors, one on either side . Also, internal fac e zones are inser ted b etween neighb oring c ell z ones tha t are connec ted b y interior fac es. •Check r ead da ta:This option enables additional checks f or the v alidit y of the mesh. Enabling this option will check the mesh t opology dur ing file r ead. In c ase inc orrect mesh t opology is enc oun tered, warning messages will b e displa yed and the er roneous en tities will b e delet ed. Note tha t in c ase of mesh t opology errors, no aut oma tic mesh r epair is done , and tha t par ts of the mesh ma y be non-c onformal, contain v oids , or b e erroneous in other w ays.The pur pose of the check-read-data option is t o enable acc ess t o corrupt files .This option is disabled b y default with the assumption tha t correct da ta will b e read, and t o shor ten file r ead times . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 104Reading and Writing F iles5.2.1.1. Reading Multiple Mesh F iles If the mesh is c ontained in t wo or mor e separ ate files , you c an r ead them t ogether in F luen t and as- semble the c omplet e mesh. For e xample , if y ou ar e creating a h ybrid mesh b y reading in a tr iangular boundar y mesh and a v olume mesh c onsisting of he xahedr al cells, read b oth files a t the same time using File → Read → Mesh... . 5.2.1.2. Reading 2D Mesh F iles in the 3D Version of F luent You c an r ead 2D meshes fr om F luen t into the 3D v ersion of F luen t by using File → Imp ort → Fluen t 2D M esh... . 5.2.2. Reading B oundar y M esh F iles To read a F luen t boundar y mesh (c ontained in a mesh file cr eated with GAMBIT or in a F luen t case file) in to Fluen t, selec t File → Read → Boundar y M esh... to op en the Selec t File dialo g box and selec t the b oundar y mesh file t o be read. This option is c onvenien t if y ou w ant to reuse the b oundar y mesh fr om a file c ontaining a lar ge v olume mesh. If the b oundar y mesh is c ontained in t wo or mor e separ ate files , you c an r ead them in t ogether and assemble the c omplet e boundar y mesh in F luen t. 5.2.3. Reading F aceted G eometr y Files fr om ANSY S Workbench in F luen t You c an r ead fac eted geometr y files (*.tgf ) exported fr om ANSY S Workbench in F luen t.To read the faceted geometr y file , use File → Read → Mesh... or File → Read → Boundar y M esh... . The naming of fac e zones c an b e controlled b y Named S elec tions defined in ANSY S Workbench. For details on e xporting fac eted geometr y from ANSY S Workbench, refer to the ANSY S Workbench H elp. 5.2.4. Appending M esh F iles You c an r ead multiple mesh files one b y one inst ead of r eading all of them a t onc e.This pr ocess is called as app ending the mesh files .To app end files , read in the first mesh file using the Selec t File dialo g box. Reop en the dialo g box and enable Append F ile(s) and r ead the r emaining files one b y one . Note Append F ile(s) is not acc essible while r eading the first mesh file . You c an also app end files using the c ommand /file/append-meshes-by-tmerge , which uses the tmer ge utilit y in ANSY S Fluen t.There is no gr aphic al in terface equiv alen t for this t ext command . Append R ules : •If zone names and IDs ar e duplic ated, the y will b e mo dified and the changes will b e reported in the c onsole . 105Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Mesh F iles•Domain inf ormation will b e retained dur ing the file app end op eration. If domain names ar e duplic ated, they will b e mo dified and the changes will b e reported in the c onsole . •Refinemen t region inf ormation will b e retained dur ing the file app end op eration. If region names ar e du- plicated, the y will b e mo dified and the changes will b e reported in the c onsole . •You c an app end files c ompr ising only edge z ones (without fac e zones). •Edge-fac e zone asso ciations will b e retained dur ing the file app end op eration. •Zone-sp ecific pr ism par amet er inf ormation will b e retained dur ing the file app end op eration. 5.2.5. Writing M esh F iles To wr ite a mesh file in the f ormat tha t can b e read b y Fluen t, selec t File → Write → Mesh... to op en the Selec t File dialo g box and sp ecify the name of the mesh file t o be wr itten. See Binar y Files (p.101) for inf ormation ab out the file f ormat. The /file/write-options command enables y ou t o set the enforce mesh topology option for wr iting mesh files .This option is disabled b y default. Enabling this option will or ient the fac e zones consist ently when the mesh file is wr itten. If nec essar y, the z ones will b e separ ated, such tha t each boundar y fac e zone has a t most t wo cell z ones as neighb ors, one on either side . Also, internal fac e zones will b e inser ted b etween neighb oring c ell z ones tha t are connec ted b y interior fac es. Note You should delet e dead z ones in the mesh b efore wr iting the mesh or c ase file f or F luen t. 5.2.6. Writing B oundar y M esh F iles Fluen t enables y ou t o wr ite a mesh file c ompr ising sp ecific b oundar y zones .This is useful f or lar ge cases wher e you ma y want to mesh diff erent par ts of the mesh separ ately and then mer ge them t o- gether .This enables y ou t o avoid fr equen t swit ching b etween domains f or such c ases .You c an wr ite out selec ted b oundar ies t o a mesh file and then cr eate the v olume mesh f or the par t in a separ ate session. You c an then r ead the sa ved mesh in to the pr evious session using the Append F ile(s) option and mer ge the par t with the r est of the mesh. To wr ite a mesh file c ompr ising selec ted b oundar ies, selec t File → Write → Boundar ies... menu it em to in voke the Write Boundar ies dialo g box and selec t the b oundar ies t o be wr itten. 5.3. Case F iles Case files c ontain the mesh, boundar y and c ell z one c onditions , and solution par amet ers f or a pr oblem. They also c ontain the inf ormation ab out the user in terface and gr aphics en vironmen t. Fluen t allo ws you t o read and wr ite either t ext or binar y files , in c ompr essed or unc ompr essed f ormats (F or details , Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 106Reading and Writing F ilessee Binar y Files (p.101) and Reading and Writing C ompr essed F iles (p.101)). Fluen t aut oma tically det ects the file t ype when r eading . Imp ortant Changing the ID of a thr ead in the meshing mo de ma y aff ect the c ase set up . In such c ases , you will b e pr ompt ed t o confir m tha t you w ant to pr oceed with the ID changing op eration. The c ommands used f or reading c ase files c an also b e used t o read na tive-format mesh files (as descr ibed in Mesh F iles (p.103)) because the mesh inf ormation is a subset of the c ase inf ormation. The c ommands for reading and wr iting c ase files ar e descr ibed in the f ollowing sec tions . 5.3.1. Reading C ase F iles 5.3.2. Writing C ase F iles 5.3.1. Reading C ase F iles To read a c ase file , selec t File → Read → Case... to op en the Selec t File dialo g box and selec t the case file t o be read. Note Cell hier archy in c ase files adapt ed in the solution mo de will b e lost when the y are read in the meshing mo de. Case files c ontaining p olyhedr al cells c an also b e read in the meshing mo de of F luen t.You c an displa y the p olyhedr al mesh, perform certain mesh manipula tion op erations , check the mesh qualit y, and so on. 5.3.2. Writing C ase F iles To wr ite a c ase file in the f ormat tha t can b e read b y Fluen t, selec t File → Write → Case. Note You should delet e dead z ones in the mesh b efore wr iting the mesh or c ase file f or F luen t. See Binar y Files (p.101) for inf ormation ab out the sa ve file f ormat. If you ar e wr iting a he xcore or C utCell mesh, enable the Write As Polyhedr a check butt on in the Selec t File dialo g box.This enables he x cells tha t are either par t of a hanging-no de sub-division or ar e at the 107Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Case F ilesboundar y of the he x-tet in terface, to be converted t o polyhedr al cells. Enabling this option p ermits the e xport of these c ells inst ead of non-c onformal meshes . Note Further manipula tion of the mesh is r estricted af ter conversion t o polyhedr a. Only limit ed operations lik e displa ying the p olyhedr al mesh, certain mesh manipula tion op erations , check ing the mesh qualit y are available f or p olyhedr al meshes . Imp ortant •Case files tha t ha ve been r ead and r e-wr itten in the meshing mo de ar e inc ompa tible with pr e- viously sa ved da ta files . Do not r ead pr eviously sa ved da ta files with the c ase file when such case files ar e transf erred or r ead in the solution mo de. •If the z one t opology changes due t o op erations p erformed in the meshing mo de, you should verify the c ase setup af ter tr ansf erring or r eading the c ase in the solution mo de. 5.3.2.1. Writing F iles Using Hier archic al D ata F ormat (HDF) When wr iting c ase files in par allel, you c an optionally use the Hier archic al D ata Format (HDF). To wr ite case files using HDF , you c an use the same menu options or TUI c ommands and simply app end .h5 to the file name . Alternatively, selec t HDF5 C ase F iles from the Files of t ype drop-do wn list in the Selec t File dialo g box. HDF files ar e alw ays binar y and mak e use of built-in c ompr ession. Thus, the y cannot b e view ed in a text edit or. However, thir d-par ty tools ar e available tha t enable y ou t o op en and e xplor e the c ontents of files sa ved in HDF f ormat. Note Files wr itten in the HDF f ormat cannot b e read in the meshing mo de. 5.4. Reading and Writing S ize-Field F iles Size-field files c ontain the siz e func tion definitions based on the par amet ers sp ecified . Selec t File → Read → Size Field ... to read a siz e-field file .This will in voke the Selec t File dialo g box, wher e you c an sp ecify the name of the siz e-field file t o be read. Note If you r ead a siz e-field file af ter sc aling the mo del, ensur e tha t the siz e-field file is appr opriate for the sc aled mo del (siz e-field v ertices should ma tch the sc aled mo del). Selec t File → Write → Size Field ... to wr ite a siz e-field file .This in vokes the Selec t File dialo g box, wher e you c an sp ecify the name of the siz e-field file t o be wr itten. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 108Reading and Writing F ilesSee Binar y Files (p.101) for inf ormation ab out the sa ve file f ormat. 5.5. Reading Scheme S our ce Files A Scheme sour ce file c an b e loaded in thr ee w ays: through the menu sy stem as a scheme file , through the menu sy stem as a jour nal file , or thr ough Scheme itself . For lar ge sour ce files , use the Selec t File dialo g box invoked b y selec ting the File → Read → Scheme ... menu it em or the Scheme load func tion. > (load "file.scm") Shorter files c an also b e loaded with File → Read → Jour nal... or the file/read-journal command in the t ext interface (or its . or source alias). > . file.scm > source file.scm In this c ase, each char acter of the file is echo ed t o the c onsole as it is r ead in the same w ay as if y ou were typing the c ontents of the file . 5.6. Creating and Reading J our nal F iles A jour nal file c ontains a sequenc e of F luen t commands , arranged as the y would b e typed in teractively into the pr ogram or en tered thr ough the user in terface.The user in terface commands ar e recorded as Scheme c ode lines in jour nal files .You c an also cr eate jour nal files manually with a t ext edit or. If you want to include c ommen ts in y our file , put a semic olon (;) at the b eginning of each c ommen t line . The pur pose of a jour nal file is t o aut oma te a ser ies of c ommands inst ead of en tering them r epeatedly on the c ommand line . It can also b e used t o pr oduce a r ecord of the input t o a pr ogram session f or later reference, although tr anscr ipt files ar e of ten mor e useful f or this pur pose (see Creating Transcr ipt Files (p.111)). Command input is tak en fr om the sp ecified jour nal file un til its end is r eached , at which time c ontrol is retur ned t o the standar d input (usually the k eyboard). Each line fr om the jour nal file is echo ed t o the standar d output (usually the scr een) as it is r ead and pr ocessed . Imp ortant A jour nal file b y design is a simple r ecord/pla yback facilit y. It contains no inf ormation ab out the sta te in which it w as recorded or the sta te in which it is b eing pla yed back. •Be careful not t o change the f older while r ecording a jour nal file . Also, try to recreate the sta te in which the jour nal w as wr itten b efore you r ead it in to the pr ogram. For e xample , if the jour nal file includes an instr uction f or F luen t to sa ve a new file with a sp ecified name , check tha t no file with tha t name e xists in y our dir ectory before you r ead in y our jour nal file . If a file with tha t name e xists and y ou r ead in y our jour nal file , it will pr ompt f or a c onfir mation t o overwrite the old file when the pr ogram r eaches the wr ite instr uction. Because the jour nal file c ontains no r esponse t o the c onfir mation r equest , Fluen t will not b e able t o continue f ollowing the instr uctions of the jour nal file . 109Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Creating and R eading J ournal F iles•Other c onditions tha t ma y aff ect the pr ogram's abilit y to perform the instr uctions c ontained in a jour nal file can b e created b y mo dific ations or manipula tions tha t you mak e within the pr ogram. For e xample , if y our jour nal file displa ys certain sur faces, you must r ead in the appr opriate mesh file before reading the jour nal file . Imp ortant At a giv en time , only one jour nal file c an b e op en f or recording . But y ou c an r ead a jour nal file a t an y time .You c an also wr ite a jour nal and a tr anscr ipt file simultaneously . •You c an r ead multiple jour nal files in one go . Selec t the files in the or der y ou w ant them r ead in F luen t in the Selec t File dialo g box. •You c an also cr eate a jour nal file tha t mak es c alls t o other jour nal files . The f ollowing is an e xample of such a nest ed jour nal file: /file/read-journal "E:/Example_journals_example1.jou" "" /file/read-journal "E:/Example_journals_example2.jou" "" /file/read-journal "E:/Example_journals_example3.jou" "" •Whene ver y ou star t recording a jour nal file , the t ext command /file/set-tui-version "XX.X" is added a t the t op of the file (wher e XX.X corresponds t o the v ersion of ANSY S Fluen t tha t is r ecord- ing the jour nal file). This t ext command c an help jour nals cr eated in an older v ersion t o work pr operly when used in a new er v ersion, as it will hide the new t ext user in terface (TUI) pr ompts and r estore the delet ed TUI pr ompts in tha t new er v ersion. If you ar e wr iting a jour nal file in a t ext edit or, it is r ecommended tha t you add /file/set-tui- version "XX.X" at the t op of the file . Note –The sp ecified v ersion must b e within t wo full r eleases of the v ersion tha t is r unning the jour nal. –To sp ecify v ersion 2019 R3, enter "19.5" for "XX.X" . •Whether y ou cho ose t o type the t ext command in full or use par tial str ings , complet e commands ar e recorded in the jour nal files . Imp ortant –Only succ essfully c omplet ed c ommands ar e recorded . For e xample , if you st opp ed an e xecution of a c ommand using Ctrl+C, it will not b e recorded in the jour nal file . –If a user in terface event happ ens while a t ext command is in pr ogress, the user in terface event is recorded first. –All default v alues ar e recorded . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 110Reading and Writing F ilesTo star t the jour naling pr ocess, selec t File → Write → Start Jour nal... . Enter a name f or the file in the Selec t File dialo g box.The jour nal r ecording b egins and the Start Jour nal menu it em b ecomes Stop Jour nal menu it em. You c an end jour nal r ecording b y selec ting Stop J our nal, or b y exiting the pr ogram. You c an r ead a jour nal file in to the pr ogram using the Selec t File dialo g box invoked b y selec ting File → Read → Jour nal... . Journal files ar e alw ays loaded in the main (t op-le vel) t ext menu , regar dless of wher e you ar e in the text menu hier archy when y ou in voke the r ead c ommand . 5.7. Creating Transcr ipt F iles A transcr ipt file c ontains a c omplet e record of all standar d input t o and output fr om F luen t (usually all keyboard and user in terface input and all scr een output). The user in terface commands ar e recorded as Scheme c ode lines in tr anscr ipt files . Fluen t creates a transcr ipt file b y recording e verything t yped as input or en tered thr ough the user in terface, and everything pr inted as output in the t ext windo w. The pur pose of a tr anscr ipt file is t o pr oduce a r ecord of the pr ogram session f or la ter reference.The transcr ipt file c annot b e read back in to the pr ogram b ecause the y contain messages and other output transcr ipt files . Imp ortant At a time , only one tr anscr ipt file c an b e op en f or recording . But y ou c an wr ite a tr anscr ipt and a jour nal file simultaneously .You c an also r ead a jour nal file while a tr anscr ipt r ecording is in pr ogress. To star t the tr anscr iption pr ocess, selec t File → Write → Start Transcr ipt.... Enter a name f or the file in the Selec t File dialo g box.The tr anscr ipt r ecording b egins and the Start Transcr ipt... menu it em becomes the Stop Transcr ipt menu it em. You c an end tr anscr ipt r ecording b y selec ting Stop Transcr ipt, or b y exiting the pr ogram. 5.8. Reading and Writing D omain F iles A complet e mesh ma y ha ve multiple domains , each ha ving its lists of no des, faces, and c ell z one IDs . A domain file is all of the domain inf ormation wr itten as a separ ate file . (A mesh file includes the domain information as one sec tion in the file .) By convention, domain file names ar e comp osed of a r oot with the suffix .dom . If you c onform to this convention, you do not ha ve to type the suffix when pr ompt ed f or a filename; it will b e added aut oma t- ically.When F luen t reads a domain file , it first sear ches f or a file with the e xact name y ou t yped. If a file with tha t name is not f ound , it will sear ch f or a file with .dom app ended t o the name .When F luen t writes a domain file ,.dom will b e added t o the name y ou t ype unless the name alr eady ends with .dom . To read the domain files in to Fluen t, selec t File → Read → Domains ... to in voke the Selec t File dialo g box and sp ecify the name of the domain file t o be read. 111Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Reading and Writing D omain F ilesIf a domain tha t is b eing r ead alr eady exists in the mesh, a w arning message is displa yed. Fluen t verifies if the z ones defining the domains e xist in the mesh. If not , it will displa y a w arning message . To wr ite domain files in F luen t, selec t File → Write → Domains ... to in voke the Selec t File dialo g box and sp ecify the name of the domain file t o be wr itten. 5.9. Imp orting F iles You c an imp ort the f ollowing file f ormats using the menu it ems in the Imp ort submenu , or using the asso ciated t ext commands: •ANSY S Prep7/c db files •CGNS files •FIDAP neutr al files •GAMBIT neutr al files •HYPERMESH ASCII files •I-deas U niversal files •NASTR AN files •PATRAN neutr al files For inf ormation ab out the f ormat of these files and details ab out imp orting them (if the imp ort commands are not a vailable on y our c omput er), see Appendix A: Imp orting B oundar y and Volume M eshes (p.505). For inf ormation ab out changing the options r elated t o mesh imp ort see Reading and Writing F iles in the Fluent U ser's G uide (p.101). Imp orting M ultiple F iles You c an also imp ort multiple files using the File → Imp ort menu . Selec t the file f ormat (for e xample , ANSYS prep7/cdb ) and the mesh t ype (sur face or v olume) t o op en the Selec t File dialo g box. Selec t the appr opriate files fr om the Files selec tion list and click OK. Appending M ultiple E xternal F iles You c an also add files of an y external f ormat to an e xisting mesh. This is k nown as app ending files .To app end e xternal files , read or imp ort the first file . Use the File → Imp ort menu and selec t the appr opriate file f ormat (for e xample ,ANSYS prep7/cdb ) and the mesh t ype (sur face or v olume). Enable Append File(s) in the Selec t File dialo g box and imp ort the nec essar y files . 5.9.1. Imp orting C AD F iles You c an imp ort CAD mo dels using the C AD r eaders or asso ciative geometr y interfaces (via plug-ins). Refer to CAD In tegration in the ANSY S Help f or detailed C AD-r elated inf ormation. For inf ormation ab out past , presen t, and futur e pla tform supp ort, see the Platform Supp ort sec tion of the ANSY S Websit e. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 112Reading and Writing F ilesUse the File → Imp ort → CAD... menu it em t o op en the Imp ort CAD G eometr y dialo g box, wher e you c an set the basic options f or imp orting C AD files . •By default , a single file will b e imp orted. Disable Imp ort Single F ile to imp ort multiple files and sp ecify the Directory and Pattern for the files t o be imp orted. Note Ensur e tha t the file pa th c ontains the appr opriate pla tform-sp ecific separ ators (f or e xample , C:\Tutorials on Windo ws systems ,Home/Tutorials on Linux sy stems). The f ollowing sp ecial char acters ar e supp orted in the file name: On Windo ws systems– + $ ^ ( ) [ ] { } @ # % _ - = , . ; ' ~ ` ! On Linux sy stems– + $ ^ ( ) [ ] { } @ # % _ - = , . : ; ' > “ ~ ` ! •Enable Append to app end C AD mo del da ta to the e xisting mo del/mesh. Note The Append option is a vailable only when a mo del/mesh has alr eady been r ead. •You c an selec t the length unit t o sc ale the mesh on imp ort; mo dels cr eated in other units will b e sc aled accordingly .The default selec tion is mm . Imp ortant The imp orted C AD mo dels ar e sc aled based on the length unit selec ted f or the meshing mode session only .When the mo del is tr ansf erred t o solution mo de, the mo del units ar e reverted t o the or iginal C AD units . Refer to Scaling the M esh (p.822) in the Fluen t User's Guide (p.1) for details on sc aling the mesh in solution mo de. •The following Tessella tion options ar e available: –If you selec t the CAD F aceting option, you c an cho ose t o refine the C AD fac eting . Enable Refine F aceting and sp ecify the Toler anc e for refinemen t and the Max S ize in the CAD F aceting C ontrols group b ox. The default v alue f or Toler anc e is 0, which implies no t essella tion (fac eting) r efinemen t dur ing imp ort. The Max S ize enables y ou t o sp ecify a maximum fac et siz e for the imp orted mo del t o avoid v ery lar ge facets dur ing the file imp ort. 113Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Imp orting F ilesThe Merge N odes option in the CAD Options dialo g box enables the mer ging of geometr y objec t nodes dur ing C AD imp ort.This option is enabled b y default when the CAD F aceting option is selec ted. Note →Use the default v alue of 0 for an initial (diagnostic) imp ort.You c an then det ermine the minimum siz e you in tend t o use f or the mesh and imp ort the file(s) again using a Toler anc e value 1/10th the in tended minimum siz e. →Due t o mer ging of no des on geometr y objec ts, the sizing c omput ed a t the fac et no des may not r epresen t the desir ed sizing . In this c ase, disable Merge N odes in the CAD Options dialo g box and r e-imp ort the geometr y objec ts. –If you selec t the CFD S urface M esh option, you need t o sp ecify the minimum and maximum fac et siz es (Min S ize,Max S ize), and the Growth R ate. Choose the t ype of Size Func tions to be used f or cr eating the sur face mesh. →By default , a Curvature size func tion will b e used f or refining the sur face mesh based on the under lying curve and sur face cur vature. Specify the Curvature Normal A ngle to be used . →You c an also use Proximit y size func tions f or cr eating the sur face mesh, based on the numb er of c ells per gap sp ecified .The pr oximit y siz e func tions c an b e sc oped t o edges , faces, or b oth fac es and edges . Note tha t for pr oximit y siz e func tions , the numb er of c ells p er gap c an b e a r eal v alue , with a minimum of 0.1 (see Proximit y (p.209) for mor e inf ormation). →The Auto-Create Sc oped S izing enables y ou t o cr eate sc oped sizing c ontrols based on the defined par amet ers: the sc ope is defined f or new objec ts cr eated dur ing imp ort.This option is enabled b y default. →You c an also cho ose t o sa ve a siz e-field file based on the defined par amet ers ( Min S ize,Max S ize, Growth R ate,Curvature Normal A ngle , and Cells P er G ap).The siz e-field will b e read on C AD imp ort. Alternatively, you c an use a pr eviously sa ved siz e-field file t o cr eate the sur face mesh b y enabling Use S ize Field F ile. Specify the Size Field F ile to be used . Note →Mesh objec t no des will alw ays be mer ged when the CFD S urface M esh is selec ted f or C AD imp ort. →The Max S ize value is limit ed t o 1/10th the b ounding b ox diagonal. →If you selec t a siz e-field file dur ing C AD imp ort, ensur e tha t siz e-field file selec ted is appr o- priate for the length units selec ted. →Surfaces with failed sur face meshes will b e separ ated in to distinc t fac e zones and will ha ve the " failed " iden tifier in the fac e zone name . →CFD Sur face Mesh options ar e not supp orted f or ANSY S ICEM CFD (*.tin) files . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 114Reading and Writing F ilesSelec ting CAD F aceting will r esult in Geometr y O bjec ts on imp ort. Selec ting CFD S urface M esh will r esult in Mesh O bjec ts on imp ort. The CAD Options dialo g box contains additional options tha t can b e set f or imp orting C AD files .The following options ar e available: •You c an cho ose t o read all C AD files in the sub directories of the selec ted dir ectory. Note CAD files with only line b odies/wir es (edge z ones) c annot b e imp orted. •You c an sa ve an in termediar y PMDB (*.pmdb) file in the dir ectory containing the C AD files imp orted. You c an use this file t o imp ort the same C AD file(s) again with diff erent options set , for a quick er imp ort than the full imp ort. A PMDB file will b e sa ved p er C AD file selec ted. •You c an cho ose t o pr ocess Named S elec tions from the C AD files , including N amed S elec tions fr om ANSY S SpaceClaim, ANSY S DesignM odeler , public ations fr om C ATIA, and so on. Additional options t o ignor e imp ort of N amed S elec tions based on pa ttern or b y wild c ard ar e available using the /file/import/cad-options/named-selections text command (see the Text Command List for details). Note Named S elec tions defined in ANSY S M eshing c annot b e imp orted. Imp ortant In gener al, names fr om the C AD file ar e retained on imp ort.Valid char acters f or ob- ject/zone names include all alphanumer ic char acters as w ell as the f ollowing sp ecial char acters: _ + - : . All other char acters, including spac es and slashes (/), are invalid. If an in valid char acter is sp ecified , it is r eplac ed b y a h yphen (-) up on imp ort. –A pr efix zone will b e added t o the objec t name and fac e zone name if the b ody, par t, file, or N amed S elec tion name b egins with a digit or a sp ecial char acter other than “_ :”. For e xample , imp orting a file .test.agdb with the option One objec t per file , will create an objec t named zone .test compr ising the fac e zone zone .test. –A suffix -sheet will b e added t o the objec t name f or sur face bodies imp orted, except f or surface bodies imp orted using the One O bjec t per par t option. •By default , the cur vature da ta fr om the no des of the C AD fac ets is imp orted.You c an cho ose t o disable this, if desir ed. •The Merge N odes option enables the mer ging of geometr y objec t no des dur ing C AD imp ort. 115Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Imp orting F ilesThis option is enabled b y default when the CAD F aceting option is selec ted. However, due t o mer ging of no des on geometr y objec ts, the sizing c omput ed a t the fac et no des ma y not r ep- resen t the desir ed sizing . In this c ase, disable Merge N odes and r e-imp ort the geometr y objec ts. Note Mesh objec t no des will alw ays be mer ged when the CFD S urface M esh is selec ted for C AD imp ort. •By default , features will b e extracted fr om the C AD mo del on imp ort.You c an cho ose t o disable this , if desir ed. Specify an appr opriate value f or Feature Angle .The default v alue is 40. •The Objec t Creation options enable y ou t o set up objec t and z one gr anular ity on imp ort. –Enable Create CAD A ssemblies to create the CAD A ssemblies tree on C AD imp ort. It represen ts the C AD tr ee as it is pr esen ted in the C AD pack age in which it w as cr eated. All sub-assembly le vels from the C AD ar e main tained on imp ort in F luen t Meshing . See CAD A ssemblies (p.199) for details . You c an sp ecify C AD objec t and z one gr anular ity using the options in the dr op-do wn lists in the Objec t Creation group b ox.You c an cho ose t o cr eate one C AD objec t per body,par t, CAD file or selec tion imp orted, wher eas the program-c ontrolled option (the default) allo ws the sof tware to mak e the appr opriate choic e.This option mak es a choic e between p er b ody and p er par t based on whether shar ed t opology is off or on, respectively. Similar ly, you c an choose t o cr eate one C AD z one p er body (default), face, or objec t imp orted. –You c an sp ecify objec t and z one gr anular ity using the options in the dr op-do wn lists in the Objec t Creation group b ox.You c an cho ose t o create one objec t per body,par t, CAD file or selec tion imp orted, wher eas the program-c ontrolled option (the default) allo ws the sof tware to mak e the appr opriate choic e.This option mak es a choic e between p er b ody and p er par t based on whether shar ed t opology is off or on, respectively. Similar ly, you c an cho ose t o create one fac e zone p er body (default), face, or objec t imp orted. Note For ANSY S ICEM CFD files (*.tin), set the objec t granular ity to one objec t per selec- tion . Imp ortant When imp orting multi-b ody par ts, it is r ecommended tha t the Objec t Creation option b e set t o one objec t per par t or one objec t per file . In this c ase, by default , the par t names fr om the C AD file will not b e included in the z one names or added as a pr efix t o the fac e zone lab els or r egion names . Also, the Tessella tion option should b e set t o CFD S urface M esh to retain the same t opology as in the C AD mo del. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 116Reading and Writing F ilesBy definition, objec ts do not shar e fac e and/or edge z ones . If the Objec t Creation option is set t o one objec t per b ody or one objec t per selec tion, common fac e/edge zones ar e duplic ated on imp ort to mak e the objec ts indep enden t. Additional imp ort options ar e available via t ext commands , see the Text Command List for details . •You c an c ontinue t o imp ort the C AD files , despit e errors or pr oblems cr eating the fac eting on c ertain sur faces, or other issues . •You c an imp ort par t names and b ody names fr om the C AD files .You c an also imp ort enclosur e and symmetr y named selec tions fr om ANSY S DesignM odeler (*.agdb) files . •You c an separ ate feature edges based on angle , connec tivit y, and named selec tions on imp ort. Edge z one names will ha ve suitable suffix es dep ending on separ ation cr iteria, order of z ones , existing z one names and other imp ort options selec ted. •You c an cho ose t o add the c omp onen t (assembly or par t) name t o the objec t/zone name . By default , the comp onen t name will b e added t o the objec t/zone name . •You c an cho ose whether t o add the par t names fr om the C AD file t o the objec t and z one names on imp ort. The default setting is auto which adds the par t names t o both objec t and z one names when objec t creation granular ity is set t o body.When the objec t creation gr anular ity is set t o par t or file, the par t names ar e not added t o the z one names , face zone lab els, or the r egion names , by default. You c an also e xplicitly selec t yes or no. •For zones without N amed S elec tions , you c an cho ose t o inher it the objec t name on imp ort.This option is disabled b y default. •When imp orting N amed S elec tions , the N amed S elec tion will b e used as the objec t/zone name b y default , according the objec t creation gr anular ity. You c an also cho ose t o mo dify z one names b y using par t or b ody names as suffix es to the N amed Selec tions spanning multiple par ts/b odies .This option is enabled b y default. •By default , Named S elec tions ar e not c onsider ed when the objec t creation gr anular ity is set t o one objec t per file .This b ehavior c an b e mo dified with the use-collection-names? text command . •You c an also imp ort the N amed S elec tions as fac e zone lab els when the CFD S urface M esh option is selec ted for Tessella tion . •You c an also add lab els t o edges c onnec ted t o a single fac e, edges c onnec ted t o multiple fac es, faces shar ed b y bodies (double c onnec ted fac es). •You c an cho ose t o remo ve the e xtension of the C AD files fr om the objec t/fac e zone names on imp ort.This option is disabled b y default. •You c an cho ose t o remo ve the pa th pr efix fr om the objec t/fac e zone names on imp ort.The default setting is auto which r emo ves the pa th pr efix fr om objec t/fac e zone names when the objec t creation gr anular ity is set t o one objec t per file .You c an also e xplicitly selec t yes or no. 117Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Imp orting F iles•You c an also cho ose t o mo dify all duplic ate objec t/zone names b y adding incr emen tal in tegers as suffix. This option is disabled b y default. Note •Compr essed C AD files (f or e xample , *.stl.zip , *.stl.gz, *.stl.bz2) c annot b e imp orted. •Filenames with DOS st yle 8.3 pa th (shor ter pa th) c annot b e imp orted. Ensur e tha t you giv e the pa th name in full while imp orting the C AD files . •Virtual t opology, suppr essed par ts/b odies , renamed par ts/b odies defined in ANSY S Mech- anic al/ANSY S Meshing will b e ignor ed dur ing C AD imp ort. •To imp ort ANSY S DesignM odeler files sa ved with blade geometr y created using ANSY S BladeM odeler (plug-in f or ANSY S DesignM odeler), ensur e tha t the G eometr y lic ense pr ef- erence is set t o ANSY S BladeM odeler as f ollows: 1. Selec t Tools > Lic ense P referenc es in the ANSY S Workbench menu . 2. Click the Geometr y tab in the License P referenc es dialo g box. 3. If ANSY S BladeM odeler is not the first lic ense list ed, then selec t it and click Move up as requir ed t o mo ve it t o the t op of the list. •When using the C ATIA V5 R eader on Linux sy stems , body hier archy inf ormation will not b e available . Only the lo west “child ” labels will app ear in the tr ee. For mor e inf ormation, refer to CAD In tegration in the ANSY S Help. •Tables of pla tform-sp ecific supp orted C AD pack ages c an b e found a t Linux in the CAD In- tegration or Windo ws in the CAD Int egration . Meshing P roblematic Imp orted C AD G eometries Certain pr oblema tic imp orted C AD geometr ies (such as multiple c oils w ound ar ound a c enterpoint) may not b e easily meshed using F luen t Meshing due t o two unchar acteristic pr operties: •The r atio of the sur face area and the squar e of the b ounding b ox diagonal is much gr eater than 1. •Projec ting a p oint located b etween the c oils c an lead t o ambiguous r esults due t o spa tial pr oximit y.This is esp ecially pr oblema tic for sur face meshing b ecause the par amet er-spac e-free appr oach is the most r obust appr oach f or the major ity of mo dels in F luen t Meshing . To avoid issues with ambiguous p oint projec tion in such geometr ies, use a plane t o split the fac e of the geometr y into an upp er half and a lo wer half : Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 118Reading and Writing F ilesFigur e 5.1: Splitting the F ace of a C oiled G eometr y When the split mo del is then imp orted in to the meshing mo de of F luen t, the single v olume is r etained , however the fac e of the v olume is split and y ou c an obtain a pr oper mesh b ecause the p oint projec tion ambiguit y no longer e xists , Figur e 5.2: Imp orted C oiled G eometr y 5.10. Saving P icture Files Graphic windo w displa ys can b e sa ved in v arious f ormats such as TIFF , EPS, and P ostScr ipt.There can be sligh t diff erences b etween pic tures and the displa yed gr aphics windo ws dep ending on y our settings and har dware, as the pic tures ma y be gener ated using the in ternal sof tware render er while the gr aphics windo ws ma y use sp ecializ ed gr aphics har dware for optimum p erformanc e.To elimina te such diff erences and sa ve these files a t the fast est r ate possible , you must f ollow all of the f ollowing b est pr actices: •Run C ortex on a suitable machine with an appr opriate gr aphics c ard and the la test dr ivers (f or details , see the ANSY S websit e). Note tha t you c an assign C ortex to a par ticular machine using the -gui_machine= command line option, or b y selec ting Specify M achine from the Graphics D ispla y M achine list in the Scheduler tab of F luen t Launcher . •Ensur e tha t Cortex / the host pr ocess is r un on a separ ate machine than tha t used f or comput e no de 0. For example , do not include the machine assigned using the -gui_machine option as the first machine in the hosts file / machine list (sp ecified using the -cnf=x command line option). •Do not set the gr aphics dr iver to null ,x11 (for Linux), or msw (for Windo ws). •When sa ving pic ture files , enable the Fast har dcopy option in the Preferenc es dialo g box (under Graphics ). 119Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Saving P icture FilesMany sy stems pr ovide a utilit y to “dump ” the c ontents of a gr aphics windo w in to a r aster file .This is gener ally the fast est metho d of gener ating a pic ture (as the sc ene is alr eady render ed in the gr aphics windo w) and guar antees tha t the pic ture will b e iden tical to the windo w. For additional inf ormation, see the f ollowing sec tions: 5.10.1. Using the S ave Picture Dialog Box 5.10.1. Using the S ave Picture Dialo g Box You c an use the Save Picture dialo g box to set the par amet ers and t o sa ve the pic ture files . For y our c onvenienc e, the Save Picture dialo g box can also b e op ened using the Save Picture butt on ( ) in the standar d toolbar .The pr ocedur e for sa ving a pic ture file is as f ollows: 1. Selec t the appr opriate file f ormat. 2. Set the c olor ing. 3. Specify the file t ype, if applic able (optional). 4. Define the r esolution, if applic able (optional). 5. Set the appr opriate options (landsc ape or ientation, whit e back ground). 6. If you ar e gener ating a windo w dump , specify the c ommand t o be used f or the dump . 7. Preview the r esult (optional). 8. Click the Save... butt on and en ter the filename in the r esulting Selec t File dialo g box. Tip Click Apply inst ead of Save... to sa ve the cur rent settings without sa ving a pic ture. The applied settings will b ecome the defaults f or subsequen t pic tures. Choosing the F ile F ormat To cho ose the file f ormat, selec t one of the f ollowing options in the Format list: EPS EPS12,JPEG ,PNG , PostScr ipt2,PPM ,TIFF3VRML4,Windo w D umps (LINUX S ystems) (p.121). 1(Enc apsula ted P ostScr ipt) output is the same as P ostScr ipt output , with the addition of A dob e Documen t Structuring C onventions (v2) sta temen ts. Currently, no pr eview bitmap is included in EPS output. Often, programs tha t imp ort EPS files use the pr eview bitmap to displa y on-scr een, although the ac tual v ector P ostScr ipt inf ormation is used f or pr inting (on a P ostScr ipt de vice).You c an sa ve EPS files in r aster or v ector format. 2Raster is an optional f ormat. 3The TIFF dr iver ma y not b e available on all pla tforms. 4VRML is a gr aphics in terchange f ormat tha t enables e xport of 3D geometr ical en tities tha t you c an displa y in the gr aphics windo w. This f ormat can c ommonly b e used b y VR sy stems and in par ticular the 3D geometr y can b e view ed and manipula ted in a w eb-br owser graphics windo w. Non-geometr ic en tities such as t ext, titles , color bars , and or ientation axis ar e not e xported. In addition, most displa y or visibilit y char acteristics set in F luen t, such as ligh ting , shading metho d, transpar ency, face and edge visibilit y, and out er fac e culling , are not e xplicitly e xported but ar e controlled b y the sof tware used t o view the VRML file . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 120Reading and Writing F ilesSpecifying the C olor Mo de You c an sp ecify which t ype of Color ing you w ant to use f or all f ormats except VRML and the Windo w Dump . Note Most mono chrome P ostScr ipt de vices will r ender Color images in shades of gr ay. Selec t Gray Sc ale to ensur e tha t the c olor r amp is r ender ed as a linear ly-incr easing gr ay ramp . Choosing the F ile Type When y ou sa ve a P ostScr ipt or EPS file , you c an cho ose either of the f ollowing file t ypes: •Raster: A raster file defines the c olor of each individual pix el in the image . Raster files ha ve a fix ed r esolution. •Vector: A vector file defines the gr aphics image as a c ombina tion of geometr ic pr imitiv es lik e lines , polygons , and t ext.Vector files ar e usually sc alable t o an y resolution. Defining the R esolution For raster files , you c an c ontrol the r esolution of the image b y sp ecifying the siz e in pix els. Set the desir ed Width and Heigh t under Resolution . If the v alues of Width and Heigh t are both z ero, the picture is gener ated a t the same r esolution as the ac tive gr aphics windo w. Note For P ostScr ipt and EPS files , specify the r esolution in dots p er inch ( DPI) inst ead of setting the width and heigh t. Picture O ptions You c an set t wo additional options f or all pic ture formats except VRML and the Windo w D ump . •Specify Landsc ape Or ientation (enabled , default) option, or disable f or P ortrait or ientation. •Specify a White Back ground (enabled , default), or disable t o use the same back ground as the gr aphics windo w. Fluen t also pr ovides options tha t enable y ou t o sa ve PostScr ipt files tha t can b e pr inted mor e quick ly. These options ar e available in the display/set/picture/driver/post-format text menu . Windo w D umps (LINUX S ystems) If you selec t the Windo w D ump format, the pr ogram will use the sp ecified Windo w D ump C ommand to sa ve the pic ture file . For e xample , if y ou w ant to use xwd to captur e a windo w, set the Windo w Dump C ommand to xwd -id %w > Fluen t will aut oma tically in terpret %w to be the ID numb er of the ac tive windo w when the dump o ccurs . 121Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Saving P icture Files•When y ou click Save..., the S elec t File dialo g box app ears . Enter the filename f or the output fr om the windo w dump (f or e xample ,myfile.xwd ). •To mak e an anima tion, save the windo w dumps in to numb ered files , using the %n variable .To do this , use the Windo w D ump C ommand xwd -id %w and t ype myfile%n.xwd as the filename in the Selec t File dialo g box. Note Each time y ou cr eate a new windo w dump , the v alue of %n incr eases b y one , so y ou need not tr ack numb ers t o the filenames manually . If you use the ImageM agick anima tion pr ogram, saving the files in MIFF f ormat (the na tive ImageM a- gick format) is mor e efficien t. In such c ases , use the ImageM agick tool import . For the Windo w Dump C ommand enter the default c ommand: import -window %w Specify the output f ormat to be MIFF b y using the .miff suffix a t the end of the filename . The windo w-dump f eature is b oth, system and gr aphics-dr iver-sp ecific .The c ommands a vailable f or dumping windo ws dep ends on y our sy stem c onfigur ation. Imp ortant The windo w dump will c aptur e the windo w exactly as it is displa yed, including the r esolution, colors , transpar ency, for e xample . For this r eason, all of the inputs tha t control these char- acteristics ar e disabled in the Save Picture dialo g box when y ou enable the Windo w D ump format. Previewing the Image Before sa ving a pic ture file , you c an pr eview the image t o be sa ved. Click Preview to apply the cur rent settings t o the ac tive gr aphics windo w so tha t you c an see the eff ects of diff erent options in teractively before sa ving the image . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 122Reading and Writing F ilesChapt er 6: Working With F luen t Guided Workflo ws The F luen t Guided w orkflows are designed t o mak e it easier t o gener ate a v olume mesh star ting fr om CAD geometr ies. Using the w orkflows, you c an use the pr edefined st eps, and add st eps of y our o wn, that walk y ou thr ough c ommon settings in F luen t in meshing mo de t o quick ly cr eate a v alid v olume mesh f or use in the F luen t solution mo de. This chapt er descr ibes the guided w orkflows tha t are available in F luen t. 6.1. Getting S tarted with the F luen t Guided Workflows 6.2. Using the Watertigh t Geometr y Workflow 6.3. Using the F ault-t oler ant Meshing Workflow 6.1. Getting S tarted with the F luen t Guided Workflo ws The guided w orkflows are available in the Workflow tab in the F luen t graphic al user in terface, and c an be used t o cr eate a c onformal, connec ted v olume mesh fr om an imp orted C AD geometr y. Selec t the appr opriate workflow fr om the Workflow tab . Available choic es ar e: •Use the Watertigh t Geometr y workflow for w ater-tigh t CAD geometr ies tha t do not r equir e much in the w ay of clean-up and mo dific ations . See Using the Watertigh t Geometr y Workflow (p.132) for a de- scription of the w orkflow and it's tasks . •Use the Fault-t oler ant Meshing workflow for mor e complic ated non-w ater-tigh t CAD geometr ies tha t may requir e some f orm of clean-up and mo dific ations (f or e xample , def ects such as o verlaps , intersec- tions , holes , duplic ates, etc.) This w orkflow can b e used f or b oth in ternal and e xternal flo ws simula tions . See Using the F ault-t oler ant Meshing Workflow (p.156) for a descr iption of the w orkflow and it's tasks . Onc e selec ted, the w orkflow is op ened and y ou c an pr oceed with w orking thr ough the e xisting tasks , or e ven cr eating cust om w orkflows by adding , grouping , or r emo ving tasks . 6.1.1. Prerequisit es for the F luen t Guided Workflows 6.1.2. Limita tions of the F luen t Guided Workflows 6.1.3. Customizing Workflows 6.1.4. Understanding Task S tates 6.1.5. Operating on Tasks 6.1.6. Grouping Tasks 6.1.7. Editing Tasks 6.1.8. Saving and L oading Workflows 6.1.9. Setting P references for Workflows 6.1.10. Getting H elp f or Workflow Tasks 6.1.1. Prerequisit es for the F luen t Guided Workflo ws The w orkflows reiy on star ting with a pr operly defined C AD geometr y, and c an supp ort geometr ies that contains multiple b odies , shar ing c ommon fac es, or e ven a single , fully enclosed b ody.To verify that an assembly of b odies ar e fully c onnec ted, use the Force Share option in SCDM, and shar e an y 123Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.faces tha t are found . If Force Share is not succ essful, the w orkflow will tr y to connec t the r emaining unconnec ted fac es.The w orkflow supp orts named selec tions fr om ANSY S DesignM odeler (DM) as w ell as gr oups fr om ANSY S SpaceClaim D irect Modeler (SCDM) if these ar e applied on fac es (not b odies). These en tities will app ear as lab els in the w orkflow. Imp ortant The use of named selec tions (DM) and gr oups (SCDM), for fac es sur rounding op enings (f or solid mo dels) and f or ar eas wher e lo cal sizing is needed , is recommended t o easily iden tify these lo cations in the w orkflow. Using named selec tions and gr oups will also impr ove per- sistence dur ing design changes and impr ove the p erformanc e for lar ger mo dels . The w orkflow recogniz es typic al naming c onventions on b oundar ies, such as "inlet ," "outlet ," "far-field ," "symmetr y," "w all," "in terior," or "in ternal." M ore pr ecisely , the changing of F luen t boundar y types based on name pa tterns is c ontrolled b y an ad vanced option, which is en- abled b y default. When enabled , the f ollowing pa tterns and c orresponding z one t ypes ar e applied on all z ones: •"inlet" maps t o a velocity-inlet zone •"outlet" maps t o a pressur e-outlet zone •"symmetr y" maps t o a symmetr y zone •"farfield" or "far-field" maps t o a pressur e-far-field zone For in ternal z ones (tha t is, internal z ones shar ed b y multiple r egions), the f ollowing pa tterns and c orresponding z one t ypes ar e applied: •"interior" or "in ternal" maps t o an internal zone •"wall" maps t o a wall zone •"fluid" or pr efixes using "enclosur e" or "air" map t o a fluid r egion Using these naming c onventions on b oundar ies will, by default , cause them t o be assigned to corresponding F luen t zone t ypes. Consequen tly, it is not recommended t o use an y of these naming c onventions within file names or within b odies or par ts in the mo del. Similar ly the use of "fluid" or "enclosur e" is , by default , used t o iden tify fluid r egions on b odies . Consequen tly, it is not recommended t o use these naming c onventions within b oundar y names . In addition, the use of "unk nown" should also b e avoided . 6.1.2. Limita tions of the F luen t Guided Workflo ws Note Zone names and their listings in v arious tasks ma y diff er sligh tly fr om pr evious r eleases , impac ting jour nal files and w orkflow templa te (.wft ) files tha t reference sp ecific z one Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 124Working With F luen t Guided Workflowsnames . In such c ases , jour nal files and t empla te files will not func tion, and y ou will need t o replac e the old z one names with the new v ersion of the z one names . Note Field-le vel user assistanc e (available b y ho vering ne xt to a field and click ing on the field's exposed help ic on) is a vailable f or man y fields of the w orkflows, however, it is not a vailable on Linux. Watertight G eometr yWorkflo w Limitations The f ollowing limita tions ha ve been obser ved in the F luen t Watertigh t Geometr y workflow: •In or der t o revert and edit an y up-t o-da te task in another session or on another c omput er sy stem (such as gener ating a v olume mesh), you will need t o ha ve the C AD geometr y file a vailable , as well as the c orrect CAD c onfigur ation, and the tasks will b e up dated fr om the Imp ort Geometr y task. •Multiple p eriodic sy stems ar e not supp orted in the w orkflow. •Using lab els in the c apping , local sizing , update boundar ies, and the mo dify mesh r efinemen t tasks will b e persist ent dur ing design changes , wher eas using z ones in these tasks is not lik ely t o be persist ent. •In addition t o the displa y options pr ovided in the w orkflow, you c an use the displa y options of the Ribbon and Outline View tr ee to visualiz e various r egions , zones , labels, edges , objec ts, etc. •The w orkflow only supp orts a single mesh objec t. Non-c onformal or o verset mesh setup is not supp or- ted. •If you need t o perform changes t o the t opology, geometr y, or the mesh, then y ou should inc orporate them in to the w orkflow using the cust om jour nal task in or der t o mak e the changes p ersist ent in the Fluen t workflow. See Customizing Workflows (p.128) for mor e inf ormation. •The following tasks and c ategor ies ha ve their o wn c orresponding limita tions: –Imp ort Geometr y →You c an only imp ort CAD geometr ies - .stl and .tgf or .msh files ar e not supp orted. →The w orkflow only fully supp orts the app ending of b odies used f or a b ody of influenc e using a cust om jour nal. –Add L ocal S izing →The w orkflow supp orts the r eading of an e xternal .szcontrol file f or ad vanced siz e control, provided tha t the siz e field is also imp orted or c omput ed within the Custom J our nal task. –Create Surface M esh →When the Shared Topology task is used , the f ollowing ad vanced options f or the Create Surface Mesh task ar e ac tually p erformed a t the end of the Shared Topology task: •Automa tic z one separ ation 125Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Getting S tarted with the F luen t Guided Workflows•Automa tic r emesh t o remo ve clust ering •Final sur face mesh impr ovemen t –Set U p Periodic B oundar ies →Automa tic p eriodicit y is not supp orted if all p eriodic fac es ar e non-planar . –Apply S hare Topology →The gap b etween t wo bodies should not e xceed 1/2 of the lo cal mesh siz e on the fac es of the gap . →The shar e topology succ ess r ate is incr eased if fac es acr oss gaps ar e par allel. –Add B oundar ies →Faces added t o a lab el ar e alw ays mer ged . –Surface Remesh →Supp ort body of influenc e (BOI) cr eated in lo cal sizing . –Boundar y Layer S ettings →The b oundar y layers settings ar e applied on all fluid r egion w alls. –Volume M esh S ettings →The w orkflow supp orts the r eading of e xternal .pzmcontrol files , and cust om jour nals , for advanced b oundar y layer settings →You c annot use diff erent volume mesh t ypes on diff erent regions . →Persist ent renaming only ensur es p ersist ence if unique b ody names ar e used . –Drawing the Volume M esh →To sho w the lo cation of the w orst v olume c ell, you must use the Displa y Grid option in the Displa y menu . –Modify M esh Refinemen t →Refinemen t uses the e xisting mesh (and not the geometr y) as the geometr y on which the mesh is refined . Hence, features tha t are not w ell c aptur ed (fr om a geometr y standp oint) cannot b e impr oved up on. –Named S elec tions on M ultiple B odies →When a N amed S elec tion is defined on multiple b odies , the w orkflow recogniz es the name but not tha t the gr oup should b e mer ged in to a single r egion. The separ ation of the b odies in to indi- vidual c ell z ones also separ ates b oundar y zones which c an incr ease the numb er of z ones c onsid- erably f or comple x mo dels . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 126Working With F luen t Guided Workflows•Limita tions f or U sing the P oly H excore Volume F ill M etho d in P arallel –The mesh qualit y ma y not b e perfect, due t o a f ew in valid c ells, and the change in siz e could b e large f or a f ew c ells in the p oly tr ansition ar ea. –Surface meshes with p oint contacts and edge c ontacts migh t lead t o sy stem failur e. Fault-t oler ant Meshing Workflo w Limitations The f ollowing limita tions ha ve been obser ved in the F luen t Fault-t oler ant Meshing workflow: •Imp ort CAD and P art Managemen t –When imp orting JT C AD da ta, the JTOpen option is a vailable on mor e recent Linux OS v ariants (requir ing a glibc supplying 'memcpy@GLIBC_2.14' ), tha t is, it is not supp orted on R ed Ha t / CentOS 6 ser ies. –When imp orting C AD da ta via the Workbench route on Linux, the SLES 15 pla tform is not supp orted. –Imp orting p olyhedr a and p oly-he xcore mesh files is not supp orted. –Imp orting C AD files is not supp orted when using r emot e Linux no des fr om Windo ws. •Extract Edge F eatures –When using the Intersec tion L oops extraction metho d, each objec t can par ticipa te only onc e for any giv en edge gr ouping (tha t is, objec ts ar e not a vailable t o shar e with separ ate gr oupings). For example , given t wo tir e objec ts (tire-1 , and tire-2 ) and a tunnel objec t (tunnel-1 ) with which the y intersec t; you c an cr eate an edge gr oup f or tire-1 ,tire-2 ,andtunnel-1 collec tively. You c annot , however, create individual edge gr oups tha t shar e tunnel-1 (for e xample , a gr ouping of tire-1 and tunnel-1 , and a separ ate gr ouping of tire-2 and tunnel-1 ). •Gener ate the S urface M esh –The w orkflow do es not supp ort adding z one-sp ecific settings (such as b oundar y layers) after the Gener ate the S urface M esh task. •Preferenc es –The w orkflow do es not fully supp ort the Write in to memor y option, so if selec ted as a pr eference, the w orkflow will use Write mesh files inst ead. See Setting P references for Workflows (p.130) for mor e inf ormation ab out pr eferences in sa ving da ta for editing tasks . •Limita tions f or U sing the P oly H excore Volume F ill M etho d in P arallel –Only 1 mesh objec t is supp orted. One c annot mesh multiple mesh objec ts. –The mesh qualit y ma y not b e perfect, due t o a f ew in valid c ells, and the change in siz e could b e large f or a f ew c ells in the p oly tr ansition ar ea. –Using p oly f or the wr app er type sur face mesh ma y gener ate a f ew p oor qualit y or in valid c ells. For a better qualit y CFD sur face mesh, use the Watertigh t Geometr y workflow. 127Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Getting S tarted with the F luen t Guided Workflows6.1.3. Customizing Workflo ws By default , the guided w orkflows consist of se veral existing tasks tha t represen t common op erations for mesh pr epar ation. In addition, you c an add and r emo ve certain tasks as needed , dep ending on wher e you ar e in the w orkflow, and the sp ecific le vel of c omple xity for y our o wn desir ed w orkflow. Each task r equir es c ertain inputs and pr ovides c ertain outputs tha t other tasks ma y dep end up on, so only c ertain task ma y be available t o add t o the w orkflow, dep ending on pr evious tasks . The tasks a vailable f or the Watertigh t Geometr y workflow ar e descr ibed in Using the Watertigh t Geometr y Workflow (p.132), wher eas the tasks a vailable f or the Fault-t oler ant Meshing workflow ar e descr ibed in Using the F ault-t oler ant Meshing Workflow (p.156). The f ollowing tasks c an b e added t o a w orkflow multiple times: •Update Regions •Add B oundar y Type •Update Boundar ies •Run C ustom J ournal Customiz ed w orkflows can b e sa ved and r eused la ter. For mor e inf ormation, see Saving and L oading Workflows (p.130). Standar d jour nals ( Creating and R eading J ournal F iles (p.109)) are supp orted in the w orkflows as w ell. While using the w orkflows, only the v alues tha t you change ar e recorded in the jour nal, mak ing them cleaner and easier t o read. Any workflow-related c ommands use the workflow prefix. For e xample: ... (%py-exec "workflow.InitializeWorkflow(WorkflowType=r'Watertight Geometry')") (%py-exec "workflow.TaskObject['Import Geometry'].Arguments.setState({r'FileName': r'D:/sample/elbow.scdoc',})") (%py-exec "workflow.TaskObject['Import Geometry'].Execute()") ... (%py-exec "workflow.TaskObject['Describe Geometry'].Execute()") (cx-use-window-id 1) (cx-set-camera-relative '(38.4549 14.9899 -8.62383) '(0 0 0) '(-0.0370945 -0.0108113 -0.141883) 0 0) (cx-use-window-id 1) (cx-set-camera-relative '(24.2404 9.77983 -16.4746) '(0 0 0) '(-0.0533986 -0.0213353 -0.0927949) 0 0) (%py-exec "workflow.TaskObject['Create Regions'].Arguments.setState({r'NumberOfFlowVolumes': 6,})") ... Customiz ed jour nal files c an b e created and added t o either w orkflow (Running C ustom J ournal Commands (p.156)).The f ollowing e xample demonstr ates a cust omiz ed sc oped pr ism c ontrol file f or boundar y layers.The e xample cr eates pr ism c ontrols and sets v arious pr operties such as the name , type, first heigh t, etc. ( ("fuselage-prisms" "last-ratio" 0.2 6 40 1.3 "fluid-1" "fluid-regions" "" "selected-face-zones" "*fuselage*") ("rest-prisms" "last-ratio" 0.1 8 40 1.1 "fluid-1" "fluid-regions" "" "selected-face-zones" "*fin* *pylon* *pod* *wing* ") ) 6.1.4. Understanding Task S tates Tasks in the w orkflow tr ee c an ha ve four sta tes: •Tasks tha t are complet e are indic ated b y a gr een check mar k icon ( ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 128Working With F luen t Guided Workflows•Tasks tha t are complet e but c ontain w arnings ar e indic ated b y a gr een check mar k icon with an ast erisk ( ).Tasks with this ic on ha ve one or mor e pr oblema tic pr operty settings , however Fluen t will still allow you t o pr oceed with defining other tasks in the w orkflow.The c onsole windo w ma y contain in- formation ab out the details sur rounding the pr oblem. Right-click the task while in this sta te and selec t Show E rrors and Warnings to displa y a dialo g the will outline the pr oblems iden tified with this task. •Tasks tha t are inc omplet e are indic ated b y a ligh tning b olt ic on ( ). •Tasks tha t requir e attention ar e indic ated b y an e xclama tion p oint icon ( ).Tasks with this ic on ha ve one or mor e pr oblema tic pr operty settings tha t requir e your a ttention b efore pr oceeding fur ther in the w orkflow.The c onsole windo w ma y contain inf ormation ab out the details sur rounding the pr oblem. Right-click the task while in this sta te and selec t Show E rrors and Warnings to displa y a dialo g the will outline the pr oblems iden tified with this task. 6.1.5. Op erating on Tasks You c an p erform v arious op erations on a task in the w orkflow tr ee b y right-click ing the task in the tree and using the c ontext menu t o: •Add new tasks t o the w orkflow by cho osing Inser t Next Task.The a vailable tasks tha t can b e inser ted are arranged b y wha t is r ecommended . •Group tasks t ogether b y selec ting them and cho osing Create Group . •Complet e, or e xecut e, a task b y cho osing Update. •Delete a task b y cho osing Delet e. •Rename a task b y cho osing Rename . The abilit y to aut oma tically displa y a task's objec ts in the gr aphics windo w (such as mesh elemen ts, facets, etc.) is disabled f or lar ger mo dels when using the Fault-t oler ant Meshing workflow, dep ending on the Task based displa y preference setting (see Setting P references for Workflows (p.130)). If a task has a par ticular displa y available , you c an displa y objec ts for tha t task in the gr aphics windo w b y hovering o ver the task in the w orkflow tr ee and selec ting the icon tha t app ears .This is useful t o quick ly visualiz e a task's objec ts without ha ving t o explicitly visit the task details . 6.1.6. Grouping Tasks In addition t o using the pr ovided tasks , you c an cr eate your o wn cust om gr oup tasks using the Create Group command on the c ontext menu in the w orkflow. A gr oup task is a c ollec tion of standar d tasks that you ha ve collec ted and gr oup ed t ogether . When y ou up date a gr oup task, the sy stem up dates all of the tasks within the gr oup sequen tially , while standar d tasks c an only b e up dated onc e (without b eing edit ed), a gr oup task c an b e up dated a t an y time . 6.1.7. Editing Tasks When a task is c omplet e and up-t o-da te, all c ontrols within tha t task ar e disabled . If you need t o mak e any changes t o an y of y our settings within the task, enable the task's c ontrols b y click ing the Edit 129Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Getting S tarted with the F luen t Guided Workflowsbutt on within the task (or click Edit in the c ontext menu fr om the w orkflow tr ee). Onc e you ha ve made your changes , click ing Update restores the task's sta te (causing all subsequen t up-t o-da te tasks t o then b ecome out-of-da te) and up dates the cur rent task with its new changes . Downstr eam tasks will remain out-of-da te un til you up date them manually . If you decide t o selec t Canc el, then all changes are disc arded and the task's sta te will r emain up-t o-da te. Some tasks include z one or lab el selec tion lists wher e you ha ve made a selec tion. To edit such tasks , enable the task's c ontrols b y click ing the Revert and E dit butt on (or click Revert and E dit in the context menu), ther eby reverting t o the task's pr evious sta te, and c ausing all subsequen t up-t o-da te tasks t o then b ecome out-of-da te. Onc e you ha ve made y our changes , click ing Update then up dates the cur rent task with its new v alues . If you decide t o selec t Canc el, then all changes ar e disc arded and the task's sta te is not r estored.The cur rent task and all do wnstr eam tasks will r emain out-of-da te un til you up date them manually . 6.1.8. Saving and L oading Workflo ws As you pr ogress thr ough using the w orkflows, you c an sa ve them a t an y time using the Save Workflo w butt on ( ).When y ou sa ve the w orkflow itself , you sa ve the tasks , sub-tasks , and their settings , as your o wn cust om w orkflow templa te for futur e use .You c an also load an y sa ved w orkflow using the Load Workflo w butt on ( ). If you mak e a mistak e in setting up y our w orkflow, you c an delet e the task (using the Delet e command in the c ontext menu f or the selec ted task), or e ven r eset the en tire workflow (using the Reset Workflo w butt on ( )). It should b e not ed tha t when y ou wr ite the mesh file ( File > Write > M esh... ), Fluen t saves the cur rent workflow along with an y mesh inf ormation within the sa ved mesh file . Note Workflows are sa ved as w orkflow templa te files (using the *.wft file e xtension). The *.wft files include the v ersion numb er of the cur rent release (f or e xample , for the 2019 R3, release , the files ar e in ternally designa ted with "version": "19.5" . 6.1.9. Setting P referenc es for Workflo ws You c an acc ess global pr eferences when using guided w orkflows in F luen t thr ough the Preferenc es dialo g. File → Preferenc es... Through the Meshing Workflo w categor y, the Preferenc es dialo g contains global settings tha t are useful when w orking with guided w orkflows: •For Saving da ta f or editing tasks , you c an det ermine ho w mesh files ar e managed when y ou edit y our w orkflow tasks . Choic es include: –Use the Write mesh files option t o sa ve a mesh file in to a t emp orary folder while editing mesh-r elated tasks within the w orkflow. →When this option is enabled (the default), Fluen t creates a mesh file f or use when a c om- plet ed mesh-r elated task needs t o be edit ed. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 130Working With F luen t Guided Workflows→When this option is disabled , Fluen t will not cr eate a mesh file , and when the c omplet ed mesh-r elated task needs t o be edit ed, Fluen t aut oma tically up dates each pr evious task in order t o gener ate the r equir ed mesh file . Disabling this pr eference is r ecommended if y ou do not need t o edit y our w orkflow tasks onc e the y ha ve been defined . –Use the Write in to memor y option t o sa ve mesh file inf ormation t o memor y while editing mesh-r elated tasks within the w orkflow. Note The Fault-t oler ant Meshing workflow do es not fully supp ort the Write in to memor y option, so if selec ted as a pr eference, the w orkflow will use Write mesh files inst ead. –Use Do not sa ve da ta to not sa ve a mesh file while editing a task. Note If the Saving da ta f or editing tasks option is set t o Do not sa ve da ta, and you ar e reverting an y changes t o a par ticular task, then up dating tha t task subsequen tly up dates all pr evious tasks . Whether the Saving da ta f or editing tasks option is set t o Write mesh files or Write in to memor y, mesh inf ormation is sa ved f or a par ticular task when the task is c omplet ed.When y ou cho ose t o edit an y settings t o a c omplet ed task, the sa ved mesh inf ormation c orresponding t o tha t task is r etrieved and the task's settings ar e restored acc ordingly . See Editing Tasks (p.129) for mor e inf ormation r everting and up dating task. •Use the Temp orary files f older field t o control wher e Fluen t will wr ite the t emp orary mesh files gener ated while using the w orkflows.You c an sp ecify a v alid lo cation, or b y default , the lo cation is set t o the %TEMP% folder on Windo ws and t o the /tmp directory on Linux. •Use the Verb osit y option t o det ermine whether or not y ou see task-r elated messages in the c onsole windo w tha t migh t assist y ou with y our w orkflow.The default is off which limits the output t o the console . •Use the Task based displa y option under Graphics S ettings to control ho w Fluen t aut oma tically displa ys items in the gr aphics windo w within the tasks of the w orkflow. –A value of auto will aut oma tically displa y objec ts (or r efinemen t regions , edge z ones , size boxes, etc.) in the gr aphics windo w within the task, based on the thr eshold v alues defined for the Automa tic displa y fac e zone limit and the Automa tic displa y fac et limit . –A value of yes will alw ays aut oma tically change displa yed objec ts in the gr aphics windo w within the task, acc ording t o the task's displa y requir emen ts. 131Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Getting S tarted with the F luen t Guided Workflows–A value of no will ne ver aut oma tically change displa yed objec ts in the gr aphics windo w, throughout the en tire workflow. 6.1.10. Getting H elp f or Workflo w Tasks You c an acc ess gener al and task-sp ecific do cumen tation f or the w orkflows and the asso ciated tasks by selec ting the Workflo w H elp butt on ( ). In addition, the w orkflows include user assistanc e for most fields without lea ving the w orkflow, available b y ho vering ne xt to a field and click ing on the field's e xposed help ic on. 6.2. Using the Watertigh t Geometr y Workflo w This sec tion descr ibes the v arious tasks tha t are pr ovided when using the Watertigh t Geometr y guided workflow: 6.2.1. Imp orting C AD G eometr ies 6.2.2. Adding L ocal Sizing 6.2.3. Creating Sur face Meshes 6.2.4. Setting U p Periodic B oundar ies 6.2.5. Descr ibing the G eometr y 6.2.6. Applying S hare Topology 6.2.7. Enclosing F luid R egions 6.2.8. Creating R egions 6.2.9. Updating R egions 6.2.10. Creating a Volume M esh 6.2.11. Updating B oundar ies 6.2.12. Impr oving the Sur face Mesh 6.2.13. Adding B oundar y Types 6.2.14. Impr oving the Volume M esh 6.2.15. Modifying M esh R efinemen t 6.2.16. Running C ustom J ournal C ommands 6.2.1. Imp orting C AD G eometr ies Use the Imp ort Geometr y task t o designa te a C AD geometr y for y our simula tion. 1.Choose a suitable option f or the Units . It is r ecommended t o work in units wher e the minimum siz e of the mesh is of the or der of one .The mesh will aut oma tically b e sc aled t o met ers while tr ansf erring the mesh t o the F luen t solv er 2.Click Advanc ed Options to acc ess additional c ontrols pr ior t o performing this task. Options include: •Use the Separ ate Zone B y option t o det ermine ho w zones ar e separ ated, either b y region alone , by region as w ell as a sp ecified separ ation angle , or neither . Zone separ ation is nec essar y if lo cal sizing needs t o be applied . Region separ ation is sufficien t for b ody sizing and/or b ody of influenc e, while separ ation b y angle is needed f or lo cal fac e sizing . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 132Working With F luen t Guided WorkflowsWhen Separ ate Zone B y is set t o region & angle , set the Separ ation A ngle to a v alue f or which CAD z ones ar e separ ated.The lo wer the v alue f or the angle , the higher the numb er of fac es tha t will b e separ ated.The default v alue is 40 degr ees. Note If you ar e separ ating z ones b y angle , and if a b ody of influenc e (BOI) is par t of the model, you must cr eate a fac e-based named selec tion or gr oup f or the BOI using DM or SCDM so tha t you ar e able t o selec t and add the BOI in the Add L ocal S izing task (see Adding L ocal Sizing (p.134)). •Set the Toler anc e (10% of min-siz e) value , det ermining the le vel of fac et refinemen t dur ing imp ort. It is r ecommended t o use a v alue ar ound 10% of the in tended minimum siz e. Using a v alue of 0 r esults in the c oarsest p ossible fac eting . •Set the Max F acet L ength value t o avoid v ery lar ge fac ets dur ing file imp ort. 3.Browse for a sp ecific File N ame . Supp orted file t ypes ar e SpaceClaim (.scdoc ) and Workbench (.agdb ) files and also .pmdb files . Note When a S paceClaim (.scdoc ) file is imp orted in to Fluen t while in meshing mo de, Fluen t also cr eates an in termediar y .pmdb file tha t can b e imp orted.The .pmdb file should always reside alongside the .scdoc file.When changes ar e made t o the geometr y in SpaceClaim, and the file is r eimp orted in to Fluen t, the or iginal .pmdb file is o verwritten. The .pmdb file c an b e mor e easily and quick ly read in to Fluen t for additional pr ocessing . Note SpaceClaim (.scdoc ) files ar e only supp orted on Windo ws.When w orking on Linux systems , however, you c an use the in termediar y .pmdb file as y our geometr y file f or the w orkflows. On Windo ws, use the Imp ort CAD G eometr y dialo g to imp ort the C AD file in to Fluen t, and enable the Save PMDB (In termediar y File) option in the Imp ort Options dialo g. After the file is imp orted, you c an mo ve the gener ated .pmdb file o ver to your Linux system t o use in y our w orkflow. 4.If you ha ve manually en tered a C AD geometr y file name , click Imp ort Geometr y, other wise the task is automa tically p erformed if y ou br owse and selec t a C AD file . If you need t o mak e adjustmen ts to an y of y our settings in this task, click Edit, mak e your changes and click Update, or click Canc el to cancel your changes . 5.Proceed t o the ne xt step in the w orkflow. 133Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the Watertigh t Geometr y Workflow6.2.2. Adding L ocal S izing You c an gain b etter control o ver the mesh siz e distr ibution b y using the Add L ocal S izing task. Using this task, you c an define sp ecific mesh siz e controls tha t op erate on sp ecific , localized, portions of the geometr y and mesh. Using this task, you c an add as man y localized siz e controls t o the w orkflow as you need , dep ending on the r equir emen ts and details of y our geometr y. Note tha t this task c an only be added t o the w orkflow pr ior t o the Create Surface M esh task. For the Would y ou lik e to add lo cal sizing? field , selec t yes if y ou need t o define lo cal sizing par a- met ers using the f ollowing st eps. Other wise , if y ou do not need t o define lo cal sizing c ontrols, keep the default of no, click Update and pr oceed t o the ne xt task. 1.Provide a Name for the new siz e control, or use the default name .The default name changes de- pending on the assigned Size Control Type. 2.Provide a Growth R ate. 3.Choose the Size Control Type. Choic es include: •Use the Face Size setting f or refining the lo cal sizing based on the fac e siz e. •Use the Body Size setting f or refining the lo cal sizing based on the b ody siz e. •Use the Body of Influenc e setting , or BOI, to assign a maximum siz e on all par ts of y our geometr y tha t falls within the b oundar ies of the b ody of influenc e. Note For a b ody tha t is asso ciated with a B ody of Influenc e (BOI b ody), keep the f ollowing in mind: –The BOI b ody must not shar e topology with the C AD mo del itself within SCDM or DM. –The BOI b ody must ha ve a unique name within SCDM or DM. –All imp orted BOI b odies must b e assigned a lo cal sizing c ontrol. •Use the Curvature setting f or refining the lo cal sizing based on the under lying cur ve and sur face curvature.This siz e control type is useful, for instanc e, in mo dels with a c ombina tion of lar ge and small scales . •Use the Proximit y setting f or refining the lo cal sizing based on the numb er of c ells p er gap sp ecified . 4.If you ar e using the Face Size,Body Size, or Body of Influenc e size control type, provide a Target M esh Size. Note Clicking in this field displa ys red b oxes in the gr aphics windo w, providing a visual r ep- resen tation of the field v alue . Use the Clear P review butt on t o hide the visualiza tion displa y. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 134Working With F luen t Guided Workflows5.If you ar e using the Curvature size control type, you ha ve the f ollowing options: •Specify a v alue f or the Local M in S ize for the cur vature siz e control. •Specify a v alue f or the Max S ize for the cur vature siz e control. •Specify a v alue f or the Curvature Normal A ngle for the cur vature. •Specify a v alue f or the Scope to field , wher e you c an lo calize the siz e control to fac es, edges , or fac es and edges . Edge selec tion selec ts the edges of a par ticular fac e. 6.If you ar e using the Proximit y size control type, you ha ve the f ollowing options: •Specify a v alue f or the Local M in S ize for the pr oximit y siz e control. •Specify a v alue f or the Max S ize for the pr oximit y siz e control. •Specify a v alue f or the Cells P er G ap.This v alue is the numb er of elemen t layers t o be gener ated in a gap f or the edge pr oximit y siz e func tion. Note tha t for pr oximit y siz e func tions , the numb er of c ells p er gap c an b e a r eal v alue , with a minimum v alue of 0.1. See Proximit y (p.209) for mor e inf ormation. •Specify a v alue f or the Scope to field , wher e you c an lo calize the siz e control to fac es, edges , or fac es and edges . 7.You c an selec t an a vailable z one or lab el to apply y our lo cal sizing changes . Choose whether t o Selec t By the z one name , or the lab el name in the list b elow. •If you Selec t By labels, in the Face Zone L abels list, you c an cho ose a lab el in the list , or en ter text to filter out the a vailable lab els in the list b efore selec ting a lab el. Note Labels or igina te from the C AD geometr y, such as fr om gr oup names in S paceClaim geometr ies, or fr om named selec tions in D esignM odeler geometr ies. •If you Selec t By zones , in the Face Zones list, you c an cho ose a z one in the list , or en ter text to filt er out the a vailable z ones in the list b efore selec ting a z one . 8.Click Add L ocal S izing . You c an add as man y local sizing c ontrols as y ou r equir e for y our w orkflow, each op erating on different zones and/or with diff erent sizing par amet ers.The siz e controls will app ear as sub-tasks under the par ent task. If you need t o mak e adjustmen ts to an y of y our settings in this task, selec t the sp ecific siz e control sub-task, click Revert and E dit, mak e your changes and click Update, or click Canc el to cancel your changes . Note If you need t o add another lo cal sizing c ontrol af ter y ou ha ve alr eady created a sur face mesh, you need t o revert and edit a t least one e xisting lo cal siz e control in or der t o properly see and use the a vailable geometr y objec ts in the gr aphics windo w and the 135Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the Watertigh t Geometr y Workflowobjec t listing . Alternatively, you c an also r e-imp ort your geometr y and up date the Add Local S izing task. 9.Onc e you ar e sa tisfied with y our changes , proceed t o the ne xt step in the w orkflow. 6.2.3. Creating S urface M eshes Use the Create Surface M esh task t o cr eate a c onformal, connec ted sur face on all of the objec ts in the geometr y, and iden tify r egions tha t will la ter b e filled with the v olume mesh. In man y cases , the default v alues will b e sufficien t for a useful CFD sur face mesh. 1.Set the Minimum S ize of the fac ets f or the sur face mesh. Note Clicking in this field displa ys red b oxes in the gr aphics windo w, providing a visual r ep- resen tation of the field v alue . Use the Clear P review butt on t o hide the visualiza tion displa y. 2.Set the Maximum S ize of the fac ets f or the sur face mesh. Note Clicking in this field displa ys red b oxes in the gr aphics windo w, providing a visual r ep- resen tation of the field v alue . Use the Clear P review butt on t o hide the visualiza tion displa y. 3.Specify the Growth R ate. 4.Choose a Size Func tion . •The Curvature size func tion c an b e used f or refining the sur face mesh based on the under lying cur ve and sur face cur vature. •The Proximit y size func tion c an b e used f or cr eating the sur face mesh, based on the numb er of c ells per gap sp ecified . •By default , a Curvature and P roximit y size func tion is assigned based on b oth cur vature and pr oximit y. For additional inf ormation, see Size Functions and Sc oped S izing (p.207). 5.For the Curvature or the Curvature and P roximit y size func tions , specify the Curvature Normal A ngle for the cur vature siz e func tion. The default v alue of 18 degr ees should appr oxima tely pr oduce 20 fac ets in the cir cumf erential dir ection of a c ylinder . 6.For the Proximit y or the Curvature and P roximit y size func tions , specify the Cells P er G ap for the proximit y siz e func tion. This v alue is the numb er of elemen t layers t o be gener ated in a gap f or the edge proximit y siz e func tion. Note tha t for pr oximit y siz e func tions , the numb er of c ells p er gap c an b e a r eal value , with a minimum v alue of 0.1. See Proximit y (p.209) for mor e inf ormation. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 136Working With F luen t Guided Workflows7.For the Proximit y or the Curvature and P roximit y size func tions , cho ose the Scope Proximit y To value for the pr oximit y siz e func tion, which c an b e sc oped t o edges , faces, or b oth fac es and edges . 8.Click Advanc ed Options to acc ess additional c ontrols pr ior t o performing this task. For additional inf orm- ation, see Face Connec tivit y Issues (p.248) and Qualit y Check ing (p.250). Options include: •Use the Check S elf-In tersec tion? field t o det ermine whether or not the sy stem will check f or self-in ter- secting fac es as par t of the sur face mesh cr eation. This check will, for e xample , det ect if shar e topology has b een omitt ed. For lar ger mo dels , this check, however, can b e time c onsuming , so if a mo del initially passes this t est the first time , it can b e saf ely disabled . Figur e 6.1: Example of a S elf-In tersec tion: Double F aces A ppear When S hare Topology is Not E nabled Figur e 6.2: Example of a S elf-In tersec tion: Local M esh S ize is S ignific antly L arger Than the Pipe Thick ness •Use the Limit f or S moothing F olded F aces option t o pr ovide a v alue limiting when f olded fac es ar e resolv ed dur ing sur face mesh cr eation. •Use the Invoke Zone S epar ation b y Angle? option t o det ermine whether or not t o separ ate zones . If set t o yes , separ ation is based on a sp ecified separ ation angle . Separ ation is needed f or op erations such as flo w volume e xtraction and mesh r efinemen ts, in c ases wher e named selec tions ha ve not b een defined in ad vance inside the C AD mo del. •Use the Separ ation A ngle option t o sp ecify a desir ed angle f or det ermining separ ation. Assigning a smaller separ ation angle will pr oduce mor e zones . •Use the Auto Assign Z one Types? option t o aut oma tically assign inlet , outlet , internal, and symmetr y boundar y types to zones dur ing sur face mesh cr eation. 137Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the Watertigh t Geometr y Workflow•Use the Invoke Qualit y Impr ove? option t o cho ose whether or not qualit y measur es ar e applied dur ing surface mesh cr eation. Sur face mesh qualit y impr ovemen ts should b e invoked af ter imp orting the C AD model. –When Invoke Qualit y Impr ove? is enabled , an a ttempt will b e made t o impr ove the qualit y on those triangles wher e the sk ewness is ab ove the Qualit y Impr ove Skewness Limit . Note If local sizing has b een added , these cur vature and pr oximit y siz e controls ar e ap- pended t o the lo cal siz es and the r esulting siz e field is used t o dic tate the siz es during sur face meshing . –When Invoke Qualit y Impr ove? is enabled , four c onsecutiv e attempts ar e made t o impr ove the qualit y, each using a lar ger adjac ent angle , until the Qualit y Impr ove M ax A ngle . –When Invoke Qualit y Impr ove? is enabled , and af ter qualit y impr ovemen ts, using the Qualit y Im- prove Skewness Limit and Qualit y Impr ove M ax A ngle are complet e, if an y remaining tr iangles are ab ove the Qualit y Impr ove Collapse S kewness Limit value , these tr iangles will b e aggr essiv ely remo ved using a fix ed maximum angle of 120 degr ees. •Use the Auto Remesh t o Remo ve Clust ering? option t o aut oma tically r emesh the sur face mesh t o remo ve excessiv e clust ering of no des. Using the default will only in voke this aut oma tic r emesh if the Add L ocal S izing task has b een added t o the w orkflow. 9.Click Create Surface M esh to gener ate a CFD sur face mesh f or the imp orted C AD geometr y. During the pr ocess of cr eating the sur face mesh f or an imp orted C AD assembly geometr y containing multiple par ts, Fluen t can det ect whether or not the geometr y has shar ed t opology enabled . If the imp orted geometr y do es not have shar ed t opology enabled , Fluen t will pr ovide y our w orkflow with a Shared Topology task (within the Descr ibe the G eometr y task, see Applying S hare Topo- logy (p.141)) wher e you c an iden tify and close an y pr oblema tic gaps and cho ose whether t o join and/or in tersec t the pr oblema tic fac es. When the Shared Topology task is used , the f ollowing ad vanced options f or the Create Surface Mesh task ar e ac tually p erformed a t the end of the Shared Topology task: •Automa tic z one separ ation •Automa tic r emesh t o remo ve clust ering •Final sur face mesh impr ovemen t If you need t o mak e adjustmen ts to an y of y our settings in this task, click Edit, mak e your changes and click Update, or click Canc el to cancel your changes . 10.Proceed t o the ne xt step in the w orkflow. Additional qualit y impr ovemen ts can b e made t o sur face meshes using the Impr ove Surface M esh task (see Impr oving the Sur face M esh (p.153)). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 138Working With F luen t Guided Workflows6.2.4. Setting U p Periodic B oundar ies You c an use the Set U p Periodic B oundar ies task t o define r otational and/or tr ansla tional p eriodicit y in your simula tion. This task essen tially r e-meshes a single p eriodic fac e to exactly ma tch the r eference side of the fac e, as w ell as define the c orresponding F luen t boundar y types (p eriodic and shado w), in prepar ation f or the F luen t solv er. If your p eriodic simula tion also in volves shar ed t opology (Applying Share Topology (p.141)), you should first in voke the Apply S hare Topology task pr ior t o the Set U p Periodic B oundar ies task. 1.Use the Type field t o cho ose whether y ou ar e creating r otational or tr ansla tional p eriodic b oundar ies. 2.Use the Metho d field t o cho ose ho w you ar e going t o define y our p eriodic b oundar y. •Choose Automa tic - pick b oth sides to define the p eriodic b oundar y based on y our z one/lab el selec tions Note When using this option, you must selec t two zones or lab els. •Choose Manual - pick r eferenc e side to manually assign pr operties of the p eriodic b oundar y. Note When using this option, you only need t o selec t a single z one or lab el. You w ould use this option in the f ollowing situa tions: –You alr eady know the p eriodicit y angle , or tr ansla tional shif t, the c omp onen ts of the or igin, and the c omp onen ts of the v ector, and which side is the r eference side . –All your p eriodic fac es ar e non-planar . –The mesh is asymmetr ic on the t wo periodic fac es, and y ou need t o use the side with the refined mesh as a r eference. For rotational p eriodicit y: a.Specify a v alue f or the Periodicit y Angle . b.For the Origin C omp onen ts, specify a v alue f or X,Y, and Z. c.For the Vector C omp onen ts, specify a v alue f or X,Y, and Z. For tr ansla tional p eriodicit y, under Transla tional S hift, specify a v alue f or X,Y, and Z. 3.Choose whether t o Selec t By the z one name or the lab el name in the list b elow. •If you Selec t By zones , in the Zones list, you c an cho ose a z one in the list , or en ter text to filt er out the a vailable z ones in the list b efore selec ting a z one . 139Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the Watertigh t Geometr y Workflow•If you Selec t By names , in the Labels list, you c an cho ose a lab el in the list , or en ter text to filt er out the a vailable lab els in the list b efore selec ting a lab el. Note Labels or igina te from the C AD geometr y, such as fr om gr oup names in S paceClaim geometr ies, or fr om named selec tions in D esignM odeler geometr ies. 4.Onc e your selec tions ar e made , click the Set U p Periodic B oundar ies butt on and pr oceed t o the next task. Onc e the task is c omplet ed, you will see an indic ator in the gr aphics windo w sho wing the origin and v ector, as w ell as up dated mesh, wher e you c an v erify tha t the p eriodic sides ha ve iden tical meshes .When the aut oma tic option is used , the c onsole displa ys the c alcula ted periodicit y angle , origin c omp onen ts, and v ector c omp onen ts for futur e reference. If you need t o mak e adjustmen ts to an y of y our settings in this task, click Edit, mak e your changes and click Update, or click Canc el to cancel your changes . Note If you r etur n to the Set U p Periodic B oundar ies task af ter cr eating a v olume mesh, you c an r estore the visibilit y of the mesh b y using the F2 hot k ey and either the Fit to Windo w icon ( ) or the Draw M esh butt on a t the b ottom of the task. 6.2.5. Descr ibing the G eometr y The Watertigh t Geometr y workflow uses the Descr ibe Geometr y task t o let y ou sp ecify the t ype of geometr y you ar e imp orting: whether it is a solid mo del, a fluid mo del, or b oth. Settings in this task determine wha t sub-tasks ar e available f or the o verall task. 1.For the Geometr y Type, cho ose fr om the f ollowing: •The geometr y consists of only solid r egions : for solid mo dels , you ar e pr ovided with sub-tasks related t o creating c apping sur faces o ver an y op enings in the geometr y, and c alcula ting r egions . •The geometr y consists of only fluid r egions with no v oids : for fluid mo dels with no p ockets, you ar e pr ovided with a sub-task f or up dating b oundar ies. •The geometr y consists of b oth fluid and solid r egions and/or v oids : for geometr ies with b oth a solid and a fluid , and p otential p ockets, you ar e pr ovided with sub-tasks r elated t o creating capping sur faces o ver an y op enings in the geometr y, updating b oundar ies, and c alcula ting r egions . 2.Indic ate whether or not y our goal is t o cover an y op enings in y our geometr y and t o extract a fluid region. 3.Indic ate whether or not y ou w ant to ha ve Fluen t convert all fluid-fluid b oundar y types fr om 'w all' t o 'internal'. The default is No, however, if you selec t Yes, Fluen t will c onvert all in terior b oundar y types Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 140Working With F luen t Guided Workflowsfrom w alls t o internal b oundar ies. Named selec tions tha t include the str ing "w all" ar e excluded fr om this c onversion. 4.Onc e your selec tions ar e made , click the Descr ibe Geometr y butt on and pr oceed t o the ne xt task. If you need t o mak e adjustmen ts to an y of y our settings in this task, click Edit, mak e your changes and click Update, or click Canc el to cancel your changes . 6.2.6. Applying S hare Topology During the pr ocess of cr eating the sur face mesh f or an imp orted C AD assembly geometr y containing multiple par ts, Fluen t can det ect whether or not the geometr y has shar ed t opology enabled . If the imp orted geometr y do es not ha ve shar ed t opology enabled , Fluen t will pr ovide y our w orkflow with an Apply S hare Topology task (within the Descr ibe the G eometr y task) wher e you c an iden tify and close an y pr oblema tic gaps and cho ose whether t o join and/or in tersec t the pr oblema tic fac es. In an assembly , each individual b ody contains all of its fac es, none of which ar e shar ed with another body, thus mak ing the mo del "non-c onformal" t o Fluen t, wher e sp ecial handling is r equir ed f or the solv er. By performing the Apply S hare Topology task, all b odies in c ontact will shar e fac es acr oss bodies , and the mo del is made "c onformal" thus mak ing the mo del c ompa tible with the F luen t solv er. Note When ANSY S SpaceClaim D esignM odeler c annot p erform a Force Share operation, the problema tic fac es ar e iden tified as sp ecific ally named selec tions (f or e xample ,Connect Topology 25 or Connect Topology 100 , and so on). You c an use such par tially shar ed t opologies within the w orkflow, however, you must r etain those sp ecific ally named selec tions - y ou should not remo ve or r ename them. 1.Specify a v alue f or the Max G ap D istanc e. 2.Click the Show M arked G aps butt on t o iden tify gaps tha t are less than the gap distanc e. Note The Max G ap D istanc e should b e equal t o or less than half of the v alue sp ecified for the Minimum S ize in the Create Surface M esh task. Also, the Max G ap D istanc e should ne ver e xceed the thick ness of a solid or fluid b ody, other wise the solid or fluid b odies ma y potentially c ollapse . Note You should b e cautious when setting an appr opriate Minimum S ize for the sur face mesh. Using an unnec essar ily small minimum siz e value , relative to the gap distanc e, may cause pr oblems gener ating a succ essful Share Topology task. See Troublesho oting G ap M arking (p.142) for mor e inf ormation. 3.Click Advanc ed Options to acc ess additional c ontrols pr ior t o performing this task. Options include: 141Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the Watertigh t Geometr y WorkflowUse the Join P air N ormal A ngle option t o sp ecify the f eature angle t o iden tify f eatures in the overlap r egion.• •Use the Initial Rela tive Join Toler anc e option t o sp ecify the t oler ance value (r elative to fac e edges) f or lo cating the o verlapping fac es. •Use the Numb er of J oin A ttempts option t o control the numb er of times the task a ttempts t o join fac es within the gap . •Use the Join Toler anc e Incr emen t option t o control the change in t oler ance with each join a ttempt. •Use the Join and In tersec t Metho d option t o control whether the gap fac es ar e joined , whether they are intersec ted, or b oth. Note The Initial Rela tive Join Toler anc e can b e aggr essiv e, in r elation t o the Numb er of J oin A ttempts , so incr easing the numb er of a ttempts ma y yield b etter results for c ertain cir cumstanc es. In addition, impr ovemen ts ar e possible if y ou cr oss-impr int overlapping fac es within S paceClaim so tha t you ha ve one-t o-one fac e ma tching . 4.Onc e your selec tions ar e made , click the Apply S hare Topology butt on and pr oceed t o the ne xt task. The task lo cates and joins pr oblema tic fac e gaps and in tersec tions thr ough a ser ies of incr e- men tal a ttempts un til the geometr y exhibits the equiv alen t of shar ed t opology. If you need t o mak e adjustmen ts to an y of y our settings in this task, click Edit, mak e your changes and click Update, or click Canc el to cancel your changes . 6.2.6.1. Troublesho oting G ap M ark ing In the Shared Topology, use the Show M arked G aps butt on t o displa y an y gaps in the geometr y less than the Max G ap D istanc e size. Gaps b etween objec t pairs ar e iden tified and highligh ted in the gr aphics windo w. Figur e 6.3: Showing M arked G aps Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 142Working With F luen t Guided WorkflowsOnc e mar ked, you c an selec t the Apply S hare Topology butt on t o up date the task and view the final results . Based on the task's default settings , pairs ar e pr ocessed and joined and/or in tersec ted acc ording to various t oler ances o ver a numb er of incr emen tal st eps, until all iden tified pairs ar e succ essfully processed and all gaps b etween par ts ar e closed . Figur e 6.4: Applying S hare Topology to M arked G aps In some c ases , sporadic gap mar kings ar e possible when the Max G ap D istanc e is not sufficien t: Figur e 6.5: Inc omplet e Gap M arking (M ax G ap D istanc e = 0.12) Impr ovemen ts can b e made b y adjusting the Max G ap D istanc e acc ordingly . Figur e 6.6: Complet e Gap M arking (M ax G ap D istanc e = 0.15) 143Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the Watertigh t Geometr y WorkflowAdditionally , using a v alue f or the gap distanc e tha t is t oo aggr essiv e ma y lead t o a c ollapse of the geometr y en tirely onc e the task is up dated. Figur e 6.7: Excessiv e Gap M arking A round a Washer (M ax G ap D istanc e = 1.2) Sligh t readjustmen ts of the Max G ap D istanc e in acc ordanc e with the minimum siz e can b e succ essful: Figur e 6.8: Proper G ap M arking A round a Washer (M ax G ap D istanc e = 0.8) In some c ase, you ma y be requir ed t o adjust and r e-adjust the v alue of the Max G ap D istanc e field so tha t all gaps ar e pr operly iden tified and closed . 6.2.7. Enclosing F luid Regions For solid mo del geometr ies, you c an use the Enclose F luid Regions (C apping) task t o cover, or c ap, any op enings in y our geometr y in or der t o later calcula te your fluid r egion(s). 1.Specify a Name for the c apping sur face, or use the default name .The default name changes de- pending on the assigned Zone Type. 2.Choose the Zone Type for the new c ap. Choic es include: •velocity-inlet •pressur e-outlet •pressur e-inlet Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 144Working With F luen t Guided Workflows•pressur e-far-field •mass-flo w-inlet •outflo w •symmetr y •wall 3.Choose whether the Cap Type will b e based on a single sur face op ening , or if it is an annular op ening with t wo sur faces. Note A single sur face op ening c an p otentially ha ve mor e than one fac e compr ising the single surface: Figur e 6.9: Example of a S ingle S urface Cap with M ultiple F aces A single sur face op ening c an also mean selec ting multiple , distinc tly separ ate, sur faces to cr eate a single c ap: Figur e 6.10: Example of a S ingle S urface Cap with M ultiple F aces Note A single named selec tion using b oth the inner and out er fac e is the only v alid selec tion for annular c apping using lab els. 145Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the Watertigh t Geometr y WorkflowFigur e 6.11: Example of an A nnular C ap Type Note The w orkflow do es not supp ort tilt ed annular fac es for c apping (highligh ted in r ed, be- low). Currently, two caps ar e created (highligh ted in gr een, below) and the r esulting intersec ting c ap must b e manually r emo ved, Figur e 6.12: Example of a P roblema tic Tilted A nnular Op ening 4.Choose whether t o Selec t By the z one name or the lab el name in the list b elow. •If you Selec t By zones , in the Zones list, you c an cho ose a z one in the list , or en ter text to filt er out the available z ones in the list b efore selec ting a z one . •If you Selec t By names , in the Labels list, you c an cho ose a lab el in the list , or en ter text to filt er out the a vailable lab els in the list b efore selec ting a lab el. Note Labels or igina te from the C AD geometr y, such as fr om gr oup names in S paceClaim geometr ies, or fr om named selec tions in D esignM odeler geometr ies. 5.Click Advanc ed Options to acc ess additional c ontrols pr ior t o performing this task. Options include: •Use the Check C ap S elf-In tersec tion? option t o control whether or not the sy stem will det ect if the capping sur face intersec ts with an y other fac e in the mo del. If an in tersec ted fac e is f ound , it is aut oma t- ically delet ed.To incr ease the efficienc y of the c apping task, this option should b e set t o no. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 146Working With F luen t Guided WorkflowsFigur e 6.13: Example of a S elf-In tersec tion: Additional C ap In tersec ts With O ther S urfaces •Use the Max C ap E dge C oun t Limit option t o control the numb er of edges tha t can b e pr esen t on the capping sur face. 6.Click Enclose F luid Regions (C apping) .The new c apping objec t will app ear in the w orkflow and in the graphics windo w. In cases wher e a fac e has multiple holes , and only a p ortion of them will b e used f or fluid e xtraction, Fluen t will c ap all holes on the fac e, and will only use the c app ed op enings tha t are requir ed f or extracting the fluid r egion. If you need t o mak e adjustmen ts to an y of y our settings in this task, click Revert and E dit, mak e your changes and click Update, or click Canc el to cancel your changes . 7.Repeat as needed f or additional inlets , outlets , etc., until all op enings ha ve been assigned a t ype and ha ve been cr eated. 8.Onc e all op enings ha ve been c overed, proceed t o the ne xt step in the w orkflow. 6.2.8. Creating Regions You c an sp ecify the numb er of fluid r egions t o be included in y our simula tion using the Create Regions task. 1.Choose the numb er of fluid v olumes y ou wish t o create in the Estima ted N umb er of F luid Regions field , or use the default v alue . Note The sy stem will det ect additional r egions if the y exist, however, it will det ect fluid r egions only wher e the y are connec ted t o capping sur faces. By default , all b odies ar e solid r egions and all v oids ar e consider ed "dead" r egions .The c onversion to a fluid r egion c an happ en in man y ways: •There is a named selec tion ma tching *fluid* or *enclosure* or air* . 147Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the Watertigh t Geometr y Workflow•Any region shar ing a b oundar y with an y of the inlet or outlet b oundar y types will aut oma tically changed t o fluid r egion. •Any region shar ing "in ternal" b oundar ies will also change t o "fluid" r egion. When c omput e regions o ccurs the estima ted v alue ar e based on e xisting fluid r egions . 2.Click Create Regions . If you need t o mak e adjustmen ts to an y of y our settings in this task, click Edit, mak e your changes and click Update, or click Canc el to cancel your changes . Note Onc e this task is c omplet ed and up dated, if fluid e xtraction is r equir ed, Fluen t will displa y the newly cr eated fluid r egions . 3.Use the Draw Regions butt on t o displa y the a vailable r egions in the gr aphics windo w. 4.When the flo w volume is gener ated, proceed t o the ne xt step in the w orkflow. For solid mo dels , you ma y pr oceed t o the Create Volume M esh task. Additional enhanc emen ts can b e made t o regions using the Update Regions task (see Updating R e- gions (p.148)). 6.2.9. Updating Regions You c an up date the pr operties of an y defined r egion using the Update Regions task. This task c an be added t o the w orkflow as man y times as y ou r equir e. The table c ontains a list of all of the defined r egions , and their assigned t ypes. 1.(optional) U se the Filter butt on t o filt er the table c ontents based on a par ticular c olumn. 2.Assign a Region N ame as needed b y double-click ing the cur rent name . You c an also r ename one or mor e regions b y selec ting them in the table , right-click, and selec t Set Region N ame in the c ontext menu , and pr ovide a new name dir ectly in the menu . 3.Assign a Region Type as needed using the c orresponding dr op-do wn menu . Available r egion t ypes include: •fluid •solid •dead Note Dead r egions ar e the same as a v oid or a p ocket in the domain, and ar e not transf erred to the F luen t solv er. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 148Working With F luen t Guided WorkflowsMultiple r egions c an b e assigned a sp ecific t ype all a t onc e by selec ting them in the table , right- click, and selec t Set Region Type in the c ontext menu , then designa te a t ype for the selec ted regions dir ectly in the menu . 4.Use the Draw Regions butt on t o displa y the a vailable r egions in the gr aphics windo w. Multiple r egions c an b e visualiz ed all a t onc e by selec ting them in the table , right-click, and selec t Draw S elec tions in the c ontext menu . 5.When y ou ar e sa tisfied with the r egion assignmen ts, click Update Regions . If you need t o mak e adjustmen ts to an y of y our settings in this task, click Revert and E dit, mak e your changes and click Update, or click Canc el to cancel your changes . 6.Onc e all r egions ha ve been up dated, proceed t o the ne xt step in the w orkflow. 6.2.10. Creating a Volume M esh You c an gener ate a c omputa tional mesh f or y our fluid v olume(s) using the Create Volume M esh task. In man y cases , the default v alues will b e sufficien t. The Create Volume M esh task ac tually p erforms t wo separ ate op erations: creating the b oundar y layer, as w ell as the cr eating the v olume mesh. Boundar y layers ar e aut oma tically added up on all the b oundar ies of all fluid r egions , except on an y boundar ies f or which a b oundar y condition (inlet , outlet , symmetr y, internal) has b een applied . On these b oundar ies, the b oundar y layers will b e impr inted on the fac e. 1.Provide b oundar y layer settings . See Prism M eshing Options f or Sc oped P risms (p.393) for mor e inf ormation. a.Choose an Offset M etho d Type.The off set metho d tha t you cho ose det ermines ho w the mesh c ells closest t o the b oundar y are gener ated. See Offset D istanc es (p.381) for mor e inf ormation. Choic es in- clude: •asp ect-ratio: allo ws you t o control the asp ect ratio of the b oundar y layer cells (or pr ism c ells) tha t are extruded fr om the base b oundar y zone .The asp ect ratio is defined as the r atio of the pr ism base length t o the pr ism la yer heigh t. •smo oth-tr ansition : allo ws you t o use the lo cal tetrahedr al elemen t siz e to comput e each lo cal initial heigh t and t otal heigh t so tha t the r ate of v olume change is smo oth. Each tr iangle tha t is b eing in- flated will ha ve an initial heigh t tha t is c omput ed with r espect to its ar ea, averaged a t the no des. This means tha t for a unif orm mesh, the initial heigh ts will b e roughly the same , while f or a v arying mesh, the initial heigh ts will v ary •unif orm: allo ws you t o gener ate every new no de (child) t o be initially the same distanc e away from its par ent no de (tha t is, the c orresponding no de on the pr evious la yer, from which the dir ection vector is p ointing). •last-r atio: allo ws you t o control the asp ect ratio of the b oundar y layer cells (or pr ism c ells) tha t are extruded fr om the base b oundar y zone .You c an sp ecify First H eigh t for the first pr ism la yer. i.If the Offset M etho d Type is set t o smo oth-tr ansition or last-r atio, specify the Transition R atio. This v alue det ermines the r atio of the heigh t of the last la yer in the infla tion and the first c ell in the v olume fill. 149Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the Watertigh t Geometr y Workflowii.If the Offset M etho d Type is set t o asp ect-ratio, specify the First A spect Ratio.You c an c ontrol the heigh ts of the infla tion la yers b y defining the asp ect ratio of the infla tions tha t are extruded from the infla tion base .The asp ect ratio is defined as the r atio of the lo cal infla tion base siz e to the infla tion la yer heigh t.The v alue f or the First A spect Ratio allo ws you t o sp ecify the first asp ect ratio t o be used . iii.If the Offset M etho d Type is set t o unif orm or last-r atio, specify the First H eigh t.This v alue is the heigh t of the first la yer of c ells in the b oundar y layer. iv.If the Offset M etho d Type is not set t o last-r atio, provide the Growth R ate.This v alue det ermines the r elative thick ness of adjac ent infla tion la yers. As you mo ve away from the fac e to which the infla tion c ontrol is applied , each succ essiv e layer is appr oxima tely one gr owth r ate fac tor thick er than the pr evious one . b.Specify the Numb er of L ayers.This v alue det ermines the maximum numb er of b oundar y layers t o be created in the mesh. c.Click Advanc ed Options to acc ess additional c ontrols pr ior t o performing this task. See Impr oving Prism M esh Q ualit y (p.389) for mor e inf ormation. Options include: •Use the Ignor e Infla tion a t Acute Angles? option t o cho ose whether t o aut oma tically ignor e infla tion layers wher e ther e are acut e angles . •Use the Infla tion G ap F actor option t o sp ecify the r elative gap b etween t wo boundar y layer caps in a nar row channel. A value of 1 indic ates a gap tha t is of the same or der as the b oundar y layer cap tr iangle siz e in the infla tion la yer. •Use the Infla tion M ax A spect Ratio option t o sp ecify the maximum asp ect ratio f or the infla tion layer when pr oximit y compr ession is applied . •Use the Infla tion M in A spect Ratio option t o sp ecify the minimum asp ect ratio f or the infla tion layer. •Use the Keep F irst Infla tion L ayer H eigh t option t o retain the initial infla tion la yer's heigh t. •Use the Adjac ent Attach A ngle option t o set the angle f or which the infla tion w ould impr int on an adjac ent boundar y. 2.Provide v olume settings . a.Choose the t ype of Volume F ill tha t you r equir e. Available options ar e: •tetrahedr al •hexcore •polyhedr a •poly-he xcore b.Indic ate whether t o Mesh S olid Regions or not. This is enabled b y default. c.If the Volume F ill metho d is set t o tetrahedr al or polyhedr a, specify the Growth R ate.This v alue determines the r elative length-based siz e change of c ells fr om the b oundar y (or the b oundar y layer cap) t owards the in terior of the domain. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 150Working With F luen t Guided Workflowsd.If the Volume F ill metho d is set t o hexcore or poly-he xcore, specify the numb er of Buff er L ayers and Peel L ayers.The buff er la yers ar e additional la yers of c ells t o alle viate an r apid tr ansition fr om finer c ells t o coarser c ells (see Buffer La yers (p.416) for details). The p eel la yers ar e additional la yers that control the gap b etween the he xahedr a core and the geometr y (see Peel La yers (p.417) for details). e.Use the Max C ell L ength field t o det ermine the maximum length of the v olume mesh c ell. Note Clicking in this field displa ys red b oxes in the gr aphics windo w, providing a visual represen tation of the field v alue . Use the Clear P review butt on t o hide the visualiz- ation displa y. f.If the Volume F ill metho d is set t o poly-he xcore or set t o tetrahedr al (with the Numb er of Layers for the b oundar y layer is gr eater than 1), the Enable P arallel M eshing option (enabled by default) allo ws you t o apply par allel pr ocessing of the v olume mesh. The Enable P arallel Meshing option is also only a vailable when the numb er of par allel pr ocessors is gr eater than 1). For inf ormation ab out par allel pr ocessing and aut oma tically par titioning the mesh, see Auto Partitioning (p.359). Disable this option if y ou ar e in terested in only gener ating the v olume mesh in ser ial mo de. g.Click Advanc ed Options to acc ess additional c ontrols pr ior t o performing this task. Options include: •Use the Invoke Persist ent Renaming option t o allo w the v olume mesh c omp onen ts to use persist ent and unique names f or the solv er.This will mak e zone names equiv alen t to region names , and will mak e cell and fac e zone names unique . Using this field is highly r ecommended for an y par ametr ic stud y. Note Persist ent renaming only w orks if all b ody names ar e unique . •Use the Use S ize Field? option t o det ermine whether or not t o use siz e fields as par t of gener ating the v olume mesh. •Use the Polyhedr al M esh F eature Angle option t o set the angle t o pr eser ve features when using a polyhedr al-based mesh. •Use the Avoid 1/8 O ctree Transition? option t o det ermine whether or not y ou w ant to avoid any potential 1:8 c ell tr ansition in the he xcore region of the v olume mesh, replacing an y abr upt change in the c ell siz e with p olyhedr al cells. •Use the Fill P olyhedr a in S olids? option t o det ermine whether or not t o apply p olyhedr al cells t o an y solids dur ing v olume meshing . •Use the Qualit y Warning Limit option t o the set the thr eshold f or when mesh qualit y warnings are gener ated. 3.Click Create Volume M esh to gener ate a v olume mesh f or the imp orted C AD geometr y. 151Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the Watertigh t Geometr y WorkflowIf you need t o mak e adjustmen ts to an y of y our settings in this task, click Edit, mak e your changes and click Update, or click Canc el to cancel your changes . 4.Use the Draw M esh butt on t o displa y the fluid and/or solid meshes . Figur e 6.14: Example of a F luid and a S olid Volume M esh Additional enhanc emen ts can b e made t o the v olume mesh using the Impr ove Volume M esh task (see Impr oving the Volume M esh (p.154)). For mor e inf ormation ab out v olume meshing , see Objec t- Based Volume M eshing (p.263). When y ou ar e sa tisfied with the v olume mesh, you c an pr oceed t o setting up y our CFD simula tion in Fluen t solv er mo de. 6.2.11. Updating B oundar ies You c an up date the pr operties of an y defined b oundar y using the Update Boundar ies task. This task can b e added t o the w orkflow as man y times as y ou r equir e. 1.Choose a Selec tion Type as either b y label or b y zone . 2.(optional) U se the Filter butt on t o filt er the table c ontents based on a par ticular c olumn. 3.(optional) R ename an y Boundar y Name by double-click ing the lab el in the table and en tering a new name . You c an also r ename a b oundar y by selec ting it in the table , right-click, and selec t Set B oundar y Name in the c ontext menu , and pr ovide a new name dir ectly in the menu . 4.(optional) R e-assign an y Boundar y Type to another v alue b y selec ting a t ype in the table and using the corresponding dr op-do wn menu . Choic es include: •velocity-inlet •pressur e-outlet Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 152Working With F luen t Guided Workflows•pressur e-inlet •pressur e-far-field •mass-flo w-inlet •symmetr y •wall •outflo w Multiple b oundar ies c an b e assigned a sp ecific t ype all a t onc e by selec ting them in the table , right- click, and selec t Set B oundar y Type in the c ontext menu , then designa te a t ype for the selec ted boundar ies dir ectly in the menu . 5.(optional) B y default , the table only lists e xternal w all b oundar ies. Selec t the List A ll Boundar ies to see additional b oundar ies, such as fluid-fluid in ternal b oundar ies. 6.When y ou ar e sa tisfied with the b oundar y assignmen ts, click Update Boundar ies. If you need t o mak e adjustmen ts to an y of y our settings in this task, click Revert and E dit, mak e your changes and click Update, or click Canc el to cancel your changes . 7.Use the Draw B oundar ies butt on t o visualiz e all b oundar ies or just w all b oundar ies. Multiple b oundar ies c an b e visualiz ed all a t onc e by selec ting them in the table , right-click, and selec t Draw S elec tions in the c ontext menu . 8.Onc e all b oundar ies ha ve been up dated, proceed t o the ne xt step in the w orkflow. Additional b oundar y types c an b e created using the Add B oundar y Type task (see Adding B oundar y Types (p.154)). 6.2.12. Impr oving the S urface M esh You c an mak e impr ovemen ts to your sur face mesh using the Impr ove Surface M esh task. For addi- tional inf ormation, see Face Connec tivit y Issues (p.248) and Qualit y Check ing (p.250). 1.Provide a v alue f or the Face Qualit y Limit . 2.Click Advanc ed Options to acc ess additional c ontrols pr ior t o performing this task. Options include: •Use the Qualit y Impr ove M ax A ngle option t o set the maximum angle b etween the nor mals of adjac ent faces dur ing mesh impr ovemen ts. •Use the Qualit y Impr ove Iterations option t o sp ecify the numb er of it erations tha t will b e performed to impr ove the mesh. •Use the Qualit y Impr ove Collapse S kewness Limit option t o sp ecify the limiting sk ewness v alue when impr oving the mesh. After qualit y impr ovemen ts using the Qualit y Impr ove M ax A ngle are performed , if an y remaining tr iangles ar e ab ove the Qualit y Impr ove Collapse S kewness Limit , these will b e ag- gressiv ely r emo ved using a fix ed maximum angle of 120 degr ees. 3.Click Impr ove Surface M esh. 153Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the Watertigh t Geometr y WorkflowIf you need t o mak e adjustmen ts to an y of y our settings in this task, click Edit, mak e your changes and click Update, or click Canc el to cancel your changes . 4.Onc e you ar e sa tisfied with y our changes , proceed t o the ne xt step in the w orkflow. Note Changing the Face Q ualit y Limit too extensiv ely c an r esult in aggr essiv e changes t o your surface mesh. 6.2.13. Adding B oundar y Types You c an cr eate additional b oundar ies f or y our simula tion using the Add B oundar y Type task. This task c an b e added t o the w orkflow as man y times as y ou r equir e. 1.Provide a Name for the new b oundar y, or use the default name .The default name changes dep end- ing on the assigned Boundar y Type. 2.Choose the Boundar y Type. Choic es include: •velocity-inlet •pressur e-outlet •pressur e-inlet •pressur e-far-field •mass-flo w-inlet •symmetr y •wall •outflo w 3.Use the Zones list t o selec t an a vailable z one t o apply t o the b oundar y. 4.Click Add B oundar y Type.The new b oundar y will app ear in the w orkflow. If you need t o mak e adjustmen ts to an y of y our settings in this task, click Revert and E dit, mak e your changes and click Update, or click Canc el to cancel your changes . 5.Onc e you ar e sa tisfied with y our changes , proceed t o the ne xt step in the w orkflow. 6.2.14. Impr oving the Volume M esh You c an mak e impr ovemen ts to your v olume mesh b y using the Impr ove Volume M esh task. 1.Provide a v alue f or the Cell Q ualit y Limit . 2.Click Advanc ed Options to acc ess additional c ontrols pr ior t o performing this task. Options include: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 154Working With F luen t Guided WorkflowsUse the Qualit y Impr ove M in A ngle option t o set the minimum angle b etween the nor mals of adjac ent faces dur ing mesh impr ovemen ts.• •Use the Qualit y Impr ove Iterations option t o sp ecify the numb er of it erations tha t will b e performed to impr ove the mesh. •Use the Ignor e Features f or Remaining B ad C ells? option t o cho ose whether or not t o ignor e pr ob- lema tic c ells. 3.Click Impr ove Volume M esh. If you need t o mak e adjustmen ts to an y of y our settings in this task, click Edit, mak e your changes and click Update, or click Canc el to cancel your changes . For mor e inf ormation, see Impr oving the M esh (p.451) or Impr oving P rism M esh Q ualit y (p.389). 4.Onc e you ar e sa tisfied with y our changes , proceed t o the ne xt step in the w orkflow. 6.2.15. Modifying M esh Refinemen t You c an p erform additional enhanc emen ts to your sur face mesh using the Modify M esh Refinemen t task. It is not r ecommended t o use this task t o coarsen the mesh lo cally, par ticular ly on cur ved sur faces, instead, perform an y coarsening op erations using the Add L ocal S izing task (see Adding L ocal Siz- ing (p.134) for mor e inf ormation). 1.Provide a Name , or use the default name ( soft_size_1 ). 2.Choose a means f or adding or c ontrolling the r emeshing using the Refinemen t Sequenc e drop-do wn menu . You c an cho ose t o simply Add a mesh r efinemen t control, and r emesh la ter when the task is complet ed and up dated, or y ou c an cho ose t o Add and Remesh a mesh r efinemen t control tha t will add the c ontrol and p erform a r emeshing op eration a t the same time . When Add & Remesh is used , and y ou selec t only one lab el, no additional labels are created. In all other c ases , a new lab el is cr eated, represen ting the selec ted z ones/lab els. 3.Specify a Local S ize. 4.Choose a selec tion metho d using the Selec t By field . •If you Selec t By zones , in the Zones list, you c an cho ose a z one in the list , or en ter text to filt er out the available z ones in the list b efore selec ting a z one . •If you Selec t By names , in the Labels list, you c an cho ose a lab el in the list , or en ter text to filt er out the a vailable lab els in the list b efore selec ting a lab el. Note Labels or igina te from the C AD geometr y, such as fr om gr oup names in S paceClaim geometr ies, or fr om named selec tions in D esignM odeler geometr ies. 5.Click Advanc ed Options to acc ess additional c ontrols pr ior t o performing this task. Options include: 155Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the Watertigh t Geometr y WorkflowUse the Remesh F eature M in A ngle option t o sp ecify the minimum angle f or which f eatures will b e preser ved up on r emeshing .• •Use the Remesh F eature M ax A ngle option t o sp ecify the maximum angle f or which f eatures will b e preser ved up on r emeshing . •Use the Remesh C orner A ngle option t o sp ecify the c orner angle f or remeshing . 6.Click Modify M esh Refinemen t.The additional sur face mesh settings will b e applied and visible . For mor e inf ormation ab out sur face meshes , see Objec t-Based Sur face Meshing (p.239). If you need t o mak e adjustmen ts to an y of y our settings in this task, click Revert and E dit, mak e your changes and click Update, or click Canc el to cancel your changes . 6.2.16. Running C ustom J our nal C ommands Customiz e your meshing w orkflow using the Run C ustom J our nal task. Use a t ext edit or to copy portions of an y of y our o wn jour nal files , and past e them in to this task t o perform additional meshing r efinemen t. See Customizing Workflows (p.128) for mor e inf ormation. Onc e you ar e sa tisfied with y our changes , click Run C ustom J our nal, and pr oceed t o the ne xt step in the w orkflow. If you need t o mak e adjustmen ts to an y of y our settings in this task, click Edit, mak e your changes and click Update, or click Canc el to cancel your changes . Note This task c an b e added t o the w orkflow as man y times as y ou r equir e, however, this task cannot b e the initial task in a cust om w orkflow. In addition, this task assumes tha t you ar e familiar with scr ipting and the a vailable standar d Fluen t commands in meshing mo de. See Query and U tility Functions in the Fluent Text Command List - Wrap F unctions in the Fluent Text Command List for mor e inf ormation. 6.3. Using the F ault-t oler ant Meshing Workflo w This sec tion descr ibes the v arious tasks tha t are pr ovided when using the Fault-t oler ant Meshing guided w orkflow: 6.3.1. Imp orting C AD G eometr ies and M anaging C AD P arts 6.3.2. Descr ibing the G eometr y and the F low 6.3.3. Enclosing F luid R egions 6.3.4. Creating Ex ternal F low Boundar ies 6.3.5. Creating L ocal Refinemen t Regions 6.3.6. Iden tifying C onstr uction Sur faces 6.3.7. Extracting E dge F eatures 6.3.8. Adding Thick ness t o Your G eometr y 6.3.9. Creating P orous R egions 6.3.10. Iden tifying R egions 6.3.11. Defining L eakage Thresholds 6.3.12. Updating Your R egion S ettings 6.3.13. Choosing M esh C ontrol Options Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 156Working With F luen t Guided Workflows6.3.14. Setting U p Size Controls 6.3.15. Gener ating the Sur face Mesh 6.3.16. Setting U p Boundar y La yer C ontrols 6.3.17. Gener ating the Volume M esh 6.3.18. Separ ating C ontacts 6.3.1. Imp orting C AD G eometr ies and M anaging C AD P arts Use the Imp ort CAD and P art Managemen t task t o imp ort one or mor e CAD files in to your simula tion and t o perform selec tive managemen t of which par ts you ma y want to include in y our simula tion, if needed . Selec ted par ts ar e then designa ted as p otential meshing objec ts, wher e selec tive settings c an be adjust ed as desir ed. Upon c ompleting the task, meshing objec ts ar e created f or la ter use in y our Fluen t simula tion. You c an imp ort one or mor e CAD geometr y files in to your w orkflow, as w ell as app end additional files as needed . Onc e sp ecified , you c an det ermine ho w the p ortions of y our C AD geometr y will b e converted into meshing objec ts for y our simula tion: aut oma tically by par t, or b y manually cho osing y our cust om parts or assemblies . Upon loading the C AD geometr y, you c an view the c omp onen ts of the C AD geometr y in the C AD Model tr ee.You c an also view p otential meshing objec ts in the M eshing M odel tr ee.Various pr operties for y our meshing objec ts (such as f eature extraction angle , or cust om r efac eting settings) c an b e view ed and adjust ed acc ordingly .When y ou ar e sa tisfied with y our meshing mo del objec ts and their pr operties, you c an c omplet e the task, ther eby creating meshing objec ts for la ter use in y our F luen t simula tion. 1.For the CAD F ile field , provide a pa th and a name f or the C AD file tha t you w ant to load in to the task, or use the ( …) butt on t o br owse for a sp ecific file . Standar d ANSY S file t ypes ar e supp orted, including .scdoc ,.agdb ,.fmd ,.fmdb ,.fmd ,.pmdb , .tgf , and .msh . Other C AD f ormats ar e also supp orted, including .jt ,.plmxml ,.stl ,.CATPart ,.CATProduct , .prt ,.x_t ,.sat ,.step ,.iges , and.igs . See, for e xample ,File F ormat Supp ort for additional formats. 2.Selec t an appr opriate Imp ort Rout e option, or k eep the default v alue , dep ending on y our r equir e- men ts and pla tform. In most c ases , the default v alue is r ecommended and should lead t o the desir ed data b eing imp orted, however, you should b e aware of and v erify the C AD c onfigur ations b eing made b ecause the y ma y be consider ed dur ing imp ort. See CAD In tegration for details . The w orkflow uses an .fmd file t o extract and p ersist C AD inf ormation f or this task. To gener ate an appr opriate .fmd file, the a vailable options f or the Imp ort Rout e dep end on the selec ted CAD File, and y our par ticular pla tform (Windo ws or Linux). The v arious Imp ort Rout e options include: •The Native option loads the C AD file na tively in to FM, and in ternally gener ates an FMD file tha t is then loaded in to the w orkflow.This option is a vailable f or .fmd ,.fmdb , and .stl file f ormats. Note Using this imp ort route, the C AD da ta should not diff er acr oss Windo ws and Linux for default settings . 157Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the F ault-t oler ant Meshing Workflow•The SCDM option uses ANSY S SpaceClaim D irect Modeler t o read the C AD file and in ternally gener ates an .fmd file tha t is then loaded in to the w orkflow.You ma y also w ant to not e an y SpaceClaim file options that you ma y ha ve configur ed. Note This r oute is only a vailable on Windo ws, and is not a vailable on Linux. •The Workbench option uses ANSY S Workbench C AD r eaders or plug-ins t o attach or load the giv en CAD file and gener ates an .fmd file tha t is then loaded in to the w orkflow. Note This r oute is a vailable on Windo ws and Linux., though not all f ormats ar e supp orted on Linux when c ompar ed t o Windo ws. Also, thir d-par ty add-on mo dules c an lead t o sligh tly diff erent CAD da ta up on imp ort (for e xample , names , assembly hier archy, etc.). •The ACIS option is the default imp ort route for .sab and .sat file t ypes. •The MSH option is the default imp ort route for .tgf and .msh file t ypes. •The JTOpen option is the default imp ort route for .jt and .plmxml file t ypes, and only fac eted data is imp orted. Note The JTOpen option is a vailable on mor e recent Linux OS v ariants (r equir ing a glibc supplying 'memcpy@GLIBC_2.14' ), tha t is, it is not supp orted on R ed Ha t / C entOS 6 ser ies. 3.For selec ted .stl files , use the File U nit field t o indic ate the units in which the file w as cr eated. Note Imp orted .stl files c an ha ve diff erent sets of units . 4.For selec ted .jt files using the JTOPEN imp ort route, you c an use the Jt L OD field t o cho ose the level of C AD t essella tion accur acy (le vel of detail) e xposed af ter imp ort. For e xample , typic ally, you migh t ha ve thr ee le vels of detail (such as , 1 for 'fine', 2 for 'medium', and 3 f or 'c oarse') but up t o ten migh t be contained in the .jt file. If a c ertain le vel of detail do es not e xist in the file , the ne xt finer le vel of detail is tak en aut oma tically. 5.Selec t an option fr om the Create M eshing O bjec t Per field . •Choose One p er par t so tha t Fluen t aut oma tically cr eates meshing objec ts for all the par ts within the CAD mo del. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 158Working With F luen t Guided Workflows•Choose Custom to be able t o manually assign which par ts of y our C AD mo del ar e to be included as meshing objec ts in y our simula tion. 6.Use the Displa y Unit field t o sp ecify the units tha t you w ant to work with when the geometr y and mesh is displa yed in the gr aphics windo w.This field also sp ecifies the dimensions of the gener ated mesh. 7.Use the Load butt on t o load the C AD file in to the task. Note You c an app end additional C AD file(s) t o your cur rently loaded C AD file . See Appending CAD F iles (p.159) for details . 8.Use the C AD M odel tr ee to visualiz e the hier archy of y our C AD mo del. By default , the C AD M odel tr ee is automa tically p opula ted with the c omp onen ts of the imp orted and/or app ended C AD file(s). For mor e information, see Working with the C AD M odel Tree (p.160) 9.Use the M eshing M odel tr ee to visualiz e the hier archy of y our meshing objec ts. •If Create M eshing O bjec ts P er is set t o One p er par t, the M eshing M odel tr ee is aut oma tically p opula ted with all of the c orresponding par ts fr om the C AD mo del, providing y ou with a pr eview of the numb er of meshing objec ts tha t will b e gener ated. •If Create M eshing O bjec ts P er is set t o Custom, the M eshing M odel tr ee is initially empt y, and y ou can selec t individual par ts and manually add them t o the M eshing M odel tr ee, providing y ou with a mor e cust omiz ed appr oach t o the numb er of meshing objec ts tha t will b e gener ated. For mor e inf ormation, see Working with the M eshing M odel Tree (p.162). 10.Set various pr operties, such as f eature extraction angle , or cust om r efac eting settings , for selec ted meshing objec ts ( ). See Setting P roperties f or M eshing M odel O bjec ts (p.164) for details . 11.Onc e your selec tions ar e made , click Create M eshing O bjec ts to gener ate a c ollec tion of meshing objec ts based on the imp orted C AD geometr y. If you need t o mak e adjustmen ts to an y of y our settings in this task, click Edit, mak e your changes and click Update, or click Canc el to cancel your changes . 12.Proceed t o the ne xt step in the w orkflow. 6.3.1.1. Appending C AD F iles Onc e a C AD file is loaded in to the Imp ort CAD and P art Managemen t task, you c an app end addi- tional files t o the cur rent CAD mo del. a.Selec t the Append check box. b.Specify additional C AD files in the Append F ile field , provide a pa th and a name f or the C AD file that you w ant to imp ort, or use the ( …) butt on t o br owse for a sp ecific file . 159Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the F ault-t oler ant Meshing Workflowc.For selec ted .stl files , use the File U nit field t o indic ate the units in which the file w as cr eated. Note Appended .stl files c an ha ve diff erent sets of units . d.For selec ted .jt files using the JTOPEN imp ort route, you c an use the Jt L OD field t o cho ose the le vel of C AD t essella tion accur acy (le vel of detail) e xposed af ter imp ort. e.Repeat as r equir ed, and when finished , selec t the Append butt on. The c ontents of the app ended file(s) ar e added t o the tr ee, after the or iginal C AD objec ts 6.3.1.2. Work ing with the C AD Mo del Tree Many CAD mo dels c ontain t ens and hundr eds of separ ate comp onen ts, and y ou migh t only b e in ter- ested in p erforming a CFD simula tion on a small p ortion of those c omp onen ts. In the C AD M odel tree, you c an tak e portions of the C AD mo del and isola te them f or y our simula tion b y mo ving them from the C AD M odel tr ee and placing them in to the M eshing M odel tr ee. Figur e 6.15: A C AD F ile L oaded in to the C AD M odel Tree •Objec ts in the C AD M odel tr ee c an b e assemblies ( ) or par ts ( ).You c an ha ve an y numb er of le vels in the tr ee. •Selec t CAD mo del objec ts dir ectly in the tr ee in or der t o perform various tasks . Use Ctrl+left-click to selec t multiple non-sequen tial objec ts in the tr ee. Use Shift+left-click to selec t multiple sequen tial objec ts in the tr ee. See Using H ot Ke y Shortcuts in the M odel Trees and the G raphics Windo w (p.168) for additional selec tion and displa y shor tcuts f or this task. Note An objec t is highligh ted when it is selec ted in the tr ee.The check box for an objec t is used f or displa ying tha t objec t in the gr aphics windo w. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 160Working With F luen t Guided WorkflowsAlternatively, you c an r ight-click the objec t dir ectly in the gr aphics windo w, and it will b ecome selec ted in the c orresponding tr ee. Use Ctrl+right-click to selec t multiple objec ts in the gr aphics windo w (and ther eby selec ting multiple objec ts in the tr ee). •Displa y a C AD mo del objec t in the gr aphics windo w by enabling the check box ( ) to the lef t of objec t in the tr ee. Likewise , to hide an objec t from view in the gr aphics windo w, disable the check box. Selec t- ing/deselec ting a par ent assembly no de in the tr ee to sho w/hide the geometr y in the gr aphics windo w allows for all of its c omp onen t par ts to also b e sho wn/hidden. •Use the Filter Text field t o perform name-based sear ching and filt ering on mo dels c ontaining a large numb er of c omp onen ts. •Selec t and mo ve objec ts fr om the C AD M odel tr ee and plac e them in the M eshing M odel tr ee: –Drag and dr op c omp onen ts fr om the C AD M odel tr ee on to the M eshing M odel tr ee on the r ight. –Alternatively, iden tify one or mor e par t(s) - b y enabling the c orresponding check box(es) - in the C AD Model tr ee, right-click and selec t Move Check ed t o Active Node in the c ontext menu , so tha t all of the gr aphic ally visible objec ts ar e mo ved t o ac tive no de –Selec t the objec t(s) dir ectly in the gr aphics windo w, and use the Ctrl+middle-click mouse butt on combina tion t o mo ve them fr om the C AD M odel tr ee to the M eshing M odel tr ee. Selec ting an objec t dir ectly in the gr aphics windo w also selec ts the c orresponding objec t in the tree.You need t o right-click on an objec t to selec t it in the gr aphics windo w. Use Ctrl+right- click to selec t multiple objec ts in the gr aphics windo w, ther eby selec ting the c orresponding objec ts in the tr ee. –As items ar e mo ved fr om the C AD M odel tr ee, the y become gr ayed out in the C AD M odel tr ee and visible in the M eshing M odel tr ee. If you mistak enly add a c omp onen t to the M eshing M odel tr ee, you c an 161Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the F ault-t oler ant Meshing Workfloweasily r emo ve it using the Rest ore to Cad M odel option fr om the c ontext menu , ther eby adding it back to the C AD M odel tr ee. •If the C AD M odel tr ee is ac tive, you c an visualiz e the check ed C AD objec ts by click ing the Show C AD Model butt on. •Various f eatures ar e available fr om the c ontext menu of the C AD M odel tr ee, dep ending on wha t is selec ted, including: –Use the Move Check ed t o Active Node option t o aut oma tically mo ve the check ed objec t to the ac tive node in the M eshing M odel tr ee. –Use the Create M eshing O bjec t for E ach P art option t o aut oma tically cr eate a par t for the selec ted objec t and mo ve it t o the M eshing M odel tr ee. –Use the Hide O thers option t o displa y only the selec ted it ems in the gr aphics windo w. 6.3.1.3. Work ing with the Meshing Mo del Tree The M eshing M odel tr ee is pr imar ily p opula ted with selec tive par ts fr om y our C AD mo del. The c om- ponen ts in the M eshing M odel tr ee will b e the piec es of y our C AD mo del tha t you w ant to include in your F luen t simula tion. They will ultima tely b ecome meshing objec ts, and visible as such, in the Outline View in y our F luen t session. Figur e 6.16: Selec ted P ortions of a C AD F ile L oaded in to the M eshing M odel Tree •Objec ts in the M eshing M odel tr ee c an b e top-le vel meshing objec ts ( ) or par ts ( ).You c an only have two levels in the tr ee. •Selec t meshing objec ts dir ectly in the tr ee in or der t o perform various tasks . Use Ctrl+left-click to selec t multiple non-sequen tial objec ts in the tr ee. Use Shift+left-click to selec t multiple sequen tial objec ts in the tr ee. See Using H ot Ke y Shortcuts in the M odel Trees and the G raphics Windo w (p.168) for additional selec tion and displa y shor tcuts f or this task. Note An objec t is highligh ted when it is selec ted in the tr ee.The check box for an objec t is used f or displa ying tha t objec t in the gr aphics windo w. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 162Working With F luen t Guided WorkflowsAlternatively, you c an r ight-click the objec t dir ectly in the gr aphics windo w, and it will b ecome selec ted in the c orresponding tr ee. Use Ctrl+right-click to selec t multiple objec ts in the gr aphics windo w, ther eby selec ting multiple objec ts in the tr ee. •Displa y a meshing objec t in the gr aphics windo w by enabling the check box ( ) to the lef t of objec t in the tr ee. Likewise , to hide an objec t from view in the gr aphics windo w, disable the check box. Selec t- ing/deselec ting a par ent assembly no de in the tr ee to sho w/hide the geometr y in the gr aphics windo w allows for all of its c omp onen t par ts to also b e sho wn/hidden. •Use the Filter Text field t o perform name-based sear ching and filt ering on mo dels c ontaining a large numb er of c omp onen ts. •Set various pr operties f or selec ted meshing objec ts ( ). See Setting P roperties f or M eshing M odel O b- jects (p.164) for details . •If the M eshing M odel tr ee is ac tive, you c an visualiz e the check ed meshing objec ts by using the Show Meshing M odel butt on a t the b ottom of the task. •Various f eatures ar e available fr om the c ontext menu of the M eshing M odel tr ee, dep ending on wher e in the hier archy you ar e located, including: –Use the Create Objec t option t o add a gener ic objec t to the tr ee. By default the M eshing M odel tr ee is empt y, however, using the Create O bjec t option fr om the context menu , you c an cr eate your o wn cust om c ollec tion of objec t categor ies, wher e you c an add c omp onen ts fr om the C AD M odel tr ee. Onc e created, you c an sa ve tha t collec tion of simu- lation meshing objec ts using the Save M eshing O bjec ts icon ( ) wher e you c an sa ve the objec t collec tion in a .mmt file. If you need t o use tha t collec tion of objec ts again, you c an use the Load M eshing O bjec ts icon ( ) and lo cate a pr eviously sa ved .mmt file. The *.mmt objec t collec tion files include the v ersion numb er of the cur rent release (f or e xample , for the 2019 R3, release , the files ar e in ternally designa ted with "version": "19.5" . You c an also use the Selec t a t empla te drop do wn field ab ove the tr ee t o cho ose an a vailable templa te of objec ts, such as External F low, which c ontains a t empla te of objec t categor ies specific t o typic al external flo w objec ts. –Use the Rename option t o assign a new name f or the selec ted objec t in the tr ee. –Use the Set as A ctive Node option t o sp ecify the cur rent no de as the ac tive no de.The ac tive no de's label is indic ated in bold.When a no de is selec ted as the ac tive no de, you ar e able t o transf er check ed CAD mo del objec ts mor e easily t o the ac tive no de using the c ontext menu . –Use the Hide O thers option t o displa y only the selec ted it ems in the gr aphics windo w. –Use the Rest ore to Cad M odel option t o remo ve the selec ted it em fr om the tr ee and r estore it in the CAD M odel tr ee. 163Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the F ault-t oler ant Meshing Workflow6.3.1.4. Setting P roperties for Meshing Mo del O bjec ts Meshing mo del objec ts list ed in the tr ee ha ve various pr operties tha t you c an set , if nec essar y. For cust om meshing objec t creation (tha t is, when y ou ha ve set the Create M eshing O bjec t Per field t o Custom), these pr operties ar e available under Advanc ed O bjec t Settings . Figur e 6.17: Properties of a S elec ted C ustom M eshing M odel O bjec t •Set the Create One Z one P er option t o objec t,par t,body, or face, acc ordingly . For instanc e, if face is selec ted, each C AD sur face or fac e will b e assigned t o a fac e zone . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 164Working With F luen t Guided Workflows•Specify a v alue f or the Feature Extraction A ngle field , or use the default v alue of 40 degr ees, to specify the angle a t which f eatures will b e extracted fr om the C AD mo del on imp ort. See Faceting Consider ations (p.166) for details . •Enable or disable the Prefix O bjec t Name t o Zone N ame acc ordingly . Enabling this allo ws for naming the c orresponding fac e zone using the objec t name as a pr efix. This option is a vailable only for cust om meshing objec t creation. •When cr eating meshing objec ts by par t, use the Refac et check box to enable or disable additional faceting r efinemen t in this task. When enabled , you c an change the fac eting of the selec ted objec t. Likewise , for cust om meshing objec t creation, use the Refac et D uring U pdate check box to enable or disable additional fac eting r efinemen t when this task is up dated. Refac eting will r efac et the or iginal CAD geometr y. Only the fac eted C AD mo del is used dur ing the meshing pr ocess. In either c ase, when disabled , nor mal C AD fac eting is p erformed as defined b y the imp orted C AD file(s). –The Deviation controls ho w far fac et edges ar e away from the mo del. 165Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the F ault-t oler ant Meshing Workflow–The Normal A ngle also c ontrols ho w far fac et edges ar e away from the mo del. Decreasing the normal angle will r esult in mor e fac ets along the cur ved edges . –The Max S ize controls the maximum siz e of the fac ets af ter the de viation and the nor mal angle are respected. In the f ollowing e xample , the lef t-hand mo del uses small v alues f or the de viation and the normal angle in or der t o captur e the cur ved sur face, and a lar ge v alue f or the maximum siz e in or der t o get lar ger fac ets on the fla t sur face.The r ight-hand mo del uses lar ger v alues f or the de viation and the nor mal angle in or der t o captur e the cur ved sur face coarsely , and a smaller v alue f or the maximum siz e in or der t o captur e the fla t sur face evenly . For cust om meshing objec t creation, you c an: –When r efac eting is enabled , use the Preview Refac et butt on t o pr eview changes t o the r efac eting settings in the gr aphics windo w while y ou ar e still within the task. Change values and r epeat as needed f or as man y objec ts in the tr ee as r equir ed. –Use the Copy Settings t o Child O bjec ts butt on t o apply changes t o these pr operties t o any child objec ts asso ciated with the selec ted par ent objec t in the tr ee. –Use the … menu butt on a t the b ottom of the task, and selec t the Save FMD option t o sa ve your changes in a new .fmd file f or futur e use .This is esp ecially useful f or par ticular ly lar ge, complic ated mo dels in which y ou ha ve made man y sp ecializ ed changes t o the pr operties (such as r efac eting), and allo ws for a fast er load time . Note tha t mir rored c omp onen ts cannot be sa ved t o the .fmd format. 6.3.1.4.1. Faceting C onsider ations Faceting is v ery imp ortant for man y reasons: if the fac eting is t oo coarse , you will lose fidelit y; if the faceting is t oo fine , then y ou will not c aptur e imp ortant features in r ounds or fillets . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 166Working With F luen t Guided WorkflowsFigur e 6.18: Faceting E xample Here the minimum fac et edge in the fillet is r oughly the same siz e as the minimum lo cal siz e control to be used . Onc e feature edges ar e extracted using 12 degr ees, you will ha ve: 167Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the F ault-t oler ant Meshing WorkflowThis will lead t o fast er gr aphics op eration (due t o ligh ter mo del), fast er meshing , and b etter feature captur ing. Even if the tar get siz e becomes lar ger (not mor e than 2 times), it will still r espect those feature lines , leading t o anisotr opic mesh, and r educ ed c ell c oun t. 6.3.1.5. Setting D ispla y O ptions for C AD Mo del and Meshing O bjec ts To change ho w diff erent comp onen ts ar e color ed and displa yed in the gr aphics windo w, use the … menu butt on a t the b ottom of the task, and selec t Displa y Options . This displa ys the Displa y Options dialo g: The Displa y Options dialo g allo w you t o selec t color pr eferences for the displa yed c omp onen ts of the C AD M odel tr ee or the M eshing M odel tr ee. Options include t o color b y Default (aut oma tic), by CAD, by Comp onen t, or b y Objec ts.You c an also pr ovide an Area S elec tion Toler anc e. 6.3.1.6. Using H ot K ey Shor tcuts in the Mo del Trees and the Gr aphics Windo w In addition t o the hot k ey shor tcuts tha t are available in F luen t in meshing mo de ( Appendix C: Shortcut Keys (p.527)), the f ollowing selec tion and displa y hot k ey shor tcuts ar e available in the Imp ort CAD and P art Managemen t task: Keys Action Ctrl+I Selec t comp onen t instanc es Selec tion ToolsCtrl+P Selec t par ent assembly f2 Clear selec tions Ctrl+Y Clear C AD M odel tr ee selec tions Ctrl+J Preview the other displa y mo de Displa y Mode ToolsCtrl+K Disable the pr eview of the other displa y mo de Ctrl+L Toggle b etween the pr eview of the other displa y mo de Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 168Working With F luen t Guided WorkflowsKeys Action Ctrl+Shift+A Show all Displa y ToolsCtrl+Shift+E Show/hide edges Ctrl+Shift+H Hide Ctrl+Shift+I Isola te Ctrl+D Comput e distanc e Miscellaneous ToolsCtrl+H Print this help Ctrl+X Position filt er f3 Toggle r ight mouse butt on f4 Toggle selec tion metho d Ctrl+A Auto sc ale Ctrl+B CAD objec t filt er 6.3.2. Descr ibing the G eometr y and the F low The Descr ibe Geometr y and F low task lets y ou sp ecify the t ype of geometr y you ha ve and the t ype of flo w you ar e trying t o simula te. Settings in this task det ermine wha t sub-tasks ar e available f or the overall task. 1.For the Flow Type, cho ose fr om the f ollowing: •If you ar e going t o be simula ting e xternal flo w over or ar ound an objec t (such as a tr uck, car, bicycle, etc.), selec t External flo w ar ound objec t and a Create External F low B oundar ies task is added to the w orkflow (see Creating Ex ternal F low Boundar ies (p.171)). •If you ar e going t o be simula ting flo w within an objec t (such as a manif old, or c atalytic c onverter, etc.), selec t Internal flo w thr ough the objec t and an Enclose F luid Regions (C apping) task is added t o the w orkflow (see Enclosing F luid R egions (p.170)). 2.For e xternal flo ws, indic ate whether or not y ou will r equir e an y enclosur es to captur e external flo w regions . If you selec t Yes, then a Create External F low B oundar ies task is added t o the w orkflow (see Creating Ex ternal F low Boundar ies (p.171)). 3.Indic ate whether or not y our geometr y will r equir e an y local refinemen t regions . If you selec t Yes, then a Create Local Refinemen t Regions task is added t o the w orkflow (see Creating L ocal Refinemen t Regions (p.173)). 4.Indic ate whether or not y our geometr y contains an y pr edefined c onstr uction sur faces (such as c ylinders for mo ving r eference frames , or c apping sur faces, etc.). If you selec t Yes, then an Iden tify C onstr uction Surface task is added t o the w orkflow (see Iden tifying C onstr uction Sur faces (p.177)). 5.Click Advanc ed Options to acc ess additional c ontrols pr ior t o performing this task. Options include: •Indic ate whether or not y our geometr y contains an y zones with z ero thick ness . If you selec t Yes, then an Add Thick ness task is added t o the w orkflow (see Adding Thick ness t o Your G eo- metr y (p.182)). •Indic ate whether or not y our geometr y will r equir e an y form of edge or f eature extraction. If you selec t Yes, then an Extract Edge F eatures task is added t o the w orkflow (see Extracting E dge Features (p.178)). 169Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the F ault-t oler ant Meshing Workflow•Indic ate whether or not y our geometr y contains an y porous r egions . If you selec t Yes, then a Create Porous Regions task is added t o the w orkflow (see Creating P orous R egions (p.184)). 6.Onc e your selec tions ar e made , click Descr ibe Geometr y and F low and pr oceed on to the ne xt task. If you need t o mak e adjustmen ts to an y of y our settings in this task, click Edit, mak e your changes and click Update, or click Canc el to cancel your changes . 6.3.3. Enclosing F luid Regions For in ternal flo w simula tions with solid mo del geometr ies, you c an use the Enclose F luid Regions (Capping) task t o cover, or c ap, any op enings in y our geometr y in or der t o later calcula te your fluid region(s). 1.Specify a Name for the c apping sur face. 2.Choose the Zone Type for the new c ap. Choic es include: •velocity-inlet •pressur e-outlet •pressur e-inlet •pressur e-far-field •mass-flo w-inlet •outflo w •symmetr y •wall 3.Choose whether t o Selec t By the z one name or the lab el name in the list b elow. •If you Selec t By zones , in the Zones list, you c an cho ose a z one in the list , or en ter text to filt er out the available z ones in the list b efore selec ting a z one .You ar e able t o selec t multiple z ones f or capping . •If you Selec t By names , in the Labels list, you c an cho ose a lab el in the list , or en ter text to filt er out the a vailable lab els in the list b efore selec ting a lab el. Note Labels or igina te from the C AD geometr y, such as fr om gr oup names in S paceClaim geometr ies, or fr om named selec tions in D esignM odeler geometr ies. 4.Click Advanc ed Options to acc ess additional c ontrols pr ior t o performing this task. Options include: •Use the Check C ap S elf-In tersec tion? option t o control whether or not the sy stem will det ect if the capping sur face intersec ts with an y other fac e in the mo del. If an in tersec ted fac e is f ound , it is aut oma t- ically delet ed.To incr ease the efficienc y of the c apping task, this option should b e set t o no. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 170Working With F luen t Guided WorkflowsFigur e 6.19: Example of a S elf-In tersec tion: Additional C ap In tersec ts With O ther S urfaces •Use the Max C ap E dge C oun t Limit option t o control the numb er of edges tha t can b e pr esen t on the capping sur face. 5.Click Enclose F luid Regions (C apping) .The new c apping objec t will app ear in the w orkflow and in the graphics windo w. In cases wher e a fac e has multiple holes , and only a p ortion of them will b e used f or fluid e xtraction, Fluen t will c ap all holes on the fac e, and will only use the c app ed op enings tha t are requir ed f or extracting the fluid r egion. If you need t o mak e adjustmen ts to an y of y our settings in this task, click Revert and E dit, mak e your changes and click Update, or click Canc el to cancel your changes . 6.Repeat as needed f or additional inlets , outlets , etc., until all op enings ha ve been assigned a t ype and ha ve been cr eated. 7.Onc e all op enings ha ve been c overed, proceed t o the ne xt step in the w orkflow. 6.3.4. Creating E xternal F low B oundar ies When simula ting e xternal flo w ar ound an objec t, your geometr y ma y not c ontain a fully defined e x- ternal flo w b oundar y.You c an manually cr eate an e xternal flo w b oundar y in this task, by defining a bounding b ox tha t sur rounds the r elevant asp ects of y our geometr y, such as ar ound a v ehicle . Figur e 6.20: An Example of an E xternal F low B oundar y 1.Specify a Name for the e xternal b oundar y, or use the default name ( tunnel ). 171Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the F ault-t oler ant Meshing Workflow2.For Metho d, selec t Create a ne w external flo w b oundar y if you ar e creating a new e xternal b oundar y, or selec t My geometr y alr ead y has an e xternal flo w b oundar y if the e xternal b oundar y is alr eady defined as par t of y our imp orted geometr y. 3.Choose whether t o Selec t By the objec t name or the z one name in the list b elow. •If you Selec t By objec t, in the Objec ts list, you c an cho ose an objec t in the list , or en ter text to filt er out the a vailable objec ts in the list b efore selec ting an objec t. •If you Selec t By zones , in the Zones list, you c an cho ose a z one in the list , or en ter text to filt er out the available z ones in the list b efore selec ting a z one . 4.Onc e one or mor e objec t(s) or z one(s) is selec ted, you c an define the e xtents of the e xternal b oundar ies around the selec tion b y defining a b ounding b ox. 5.For new e xternal flo w regions , additional settings ar e requir ed. When y ou selec t Ratio r elative to geometr y siz e, the Box Paramet ers hold the minimum and maximum e xtension r atios f or the X, Y, and Z dimensions . By default , the y are set t o extend the dimensions of a b ounding b ox around y our selec ted objec t(s) or z one(s) out b y a fac tor equiv alen t to the t otal singular length of the geometr y in the X, Y, and Z dir ections .You c an change the v alues according t o your needs , and the displa y in the gr aphics windo w will change acc ordingly . When y ou selec t Directly sp ecify c oordina tes, the Box Paramet ers hold the minimum and max- imum e xtension distanc e for the X, Y, and Z dimensions . By default , the y are set t o values tha t correspond t o the e xtension r atios, but y ou c an set them t o mor e suitable v alues as r equir ed, and the displa y in the gr aphics windo w will change acc ordingly . Figur e 6.21: An External F low B ounding B ox 6.Onc e your selec tions ar e made , click Create External F low B oundar ies and pr oceed on to the ne xt task. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 172Working With F luen t Guided WorkflowsFigur e 6.22: An External F low B oundar y Around a C ar If you need t o mak e adjustmen ts to an y of y our settings in this task, click Revert and E dit, mak e your changes and click Update, or click Canc el to cancel your changes . 6.3.5. Creating L ocal Refinemen t Regions When simula ting flo w within and ar ound an objec t, your geometr y ma y not c ontain a fully defined refinemen t region, or b ody of influenc e (BOI). If a v olume r egion needs mesh r efinemen t, tha t region can b e iden tified b y watertigh t sur face.You c an manually cr eate such a sur face in this task b y: defining a bounding b ox around one or mor e selec ted objec ts; using one or mor e existing objec ts tha t ha ve already been imp orted; or cr eating an off set sur face. For e xample , this v olume r egion, which sur rounds the r elevant asp ects of y our flo w ph ysics, can b e used t o as an alt ernative to refine the mesh in a particular ar ea, such as the w ake region b ehind a v ehicle . Figur e 6.23: An Example of a Refinemen t Region A round a C ar 1.For Type, cho ose fr om the f ollowing: •Selec t Box to define a b ounding b ox for the r efinemen t region. •Selec t Existing if the r efinemen t region is alr eady defined as par t of y our imp orted geometr y. •Selec t Offset S urface if the r efinemen t region will b e off set fr om the sur face of an e xisting objec t or zone tha t you will selec t. 2.Specify a Name for the b ody of influenc e, or use the default name ( local-refinement-1 ). 3.Specify a v alue f or the Min S ize for the r efinemen t region. 4.Choose whether t o Selec t By the objec t name or the z one name in the list b elow. 173Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the F ault-t oler ant Meshing Workflow•If you Selec t By objec t, in the Objec ts list, you c an cho ose an objec t in the list , or en ter text to filt er out the a vailable objec ts in the list b efore selec ting an objec t. •If you Selec t By zones , in the Zones list, you c an cho ose a z one in the list , or en ter text to filt er out the available z ones in the list b efore selec ting a z one . 5.Onc e one or mor e objec t(s) or z one(s) is selec ted, you c an define the e xtents of the r efinemen t region around the selec tion b y defining a b ounding b ox. 6.Depending on the Type of r efinemen t region, additional par amet ers ar e requir ed. •For a Box refinemen t region: –When y ou selec t Ratio r elative to geometr y siz e, the Box Paramet ers hold the minimum and maximum e xtension r atios f or the X, Y, and Z dimensions . By default , the y are set t o extend the di- mensions of a b ounding b ox around y our selec ted objec t(s) or z one(s) out b y a fac tor equiv alen t to the t otal singular length of the geometr y in the X, Y, and Z dir ections .You c an change the v alues according t o your needs , and the displa y in the gr aphics windo w will change acc ordingly . –When y ou selec t Directly sp ecify c oordina tes, the Box Paramet ers hold the minimum and maximum extension distanc e for the X, Y, and Z dimensions . By default , the y are set t o values tha t correspond Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 174Working With F luen t Guided Workflowsto the e xtension r atios, but y ou c an set them t o mor e suitable v alues as r equir ed, and the displa y in the gr aphics windo w will change acc ordingly . •For an Offset S urface refinemen t region: –Specify the Flow D irection . It is used t o det ermine the w ake.The w ake is do wnstr eam of the selec ted geometr y objec t(s). –Use the Flip option if the flo w dir ection is in opp osite dir ection. –Specify a v alue f or the Defeaturing S ize, or use the default v alue .This will obtain the r ough shap e of the selec ted objec t(s), which ar e wr app ed using this siz e. –Specify a v alue f or the Total B oundar y Layer H eigh t, or use the default v alue .This ho w far fr om the selec ted objec t (s) the r ough shap e is off set. –Specify a v alue f or the Boundar y Layer L evels, or use the default v alue , to det ermine the numb er of off set sur faces to be created. –Specify a v alue f or the Wake Growth L evels, or use the default v alue .The r ough shap e is sc aled in the w ake dir ection as w ell as in the cr oss-w ake dir ection. This v alue det ermines ho w man y scaled offsets ar e to be created. –Specify a v alue f or the Wake Growth F actor, or use the default v alue . Each sc aled off set sur face is grown in siz e in the w ake dir ection b y this fac tor fr om the pr evious sc aled off set. –Specify a v alue f or the Cross Wake Growth F actor, or use the default v alue . Each sc aled off set sur face is gr own in siz e in the cr oss-w ake dir ection b y this fac tor fr om the pr evious sc aled off set. For e xample , given an aut omobile geometr y, the base is the sur face on the v ehicle , which has maximum siz e of 8 mm. The f ollowing siz e control settings w ere aut oma tically gener ated: Max SizeSize Func tionName 8 soft name 16 boi name-1 32 boi name-2 64 boi name-w ake-1 128 boi name-w ake-2 256 boi name-w ake-3 512 boi name-w ake-4 The r efinemen t regions and the v arious settings c an b e visualiz ed using Figur e 6.24: An Example of M ultiple R efinemen t Regions A round a C ar (p.176) and Figur e 6.25: An Example of M ultiple Refinemen t Regions A round a Vehicle (p.176). 175Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the F ault-t oler ant Meshing WorkflowFigur e 6.24: An Example of M ultiple Refinemen t Regions A round a C ar Figur e 6.25: An Example of M ultiple Refinemen t Regions A round a Vehicle Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 176Working With F luen t Guided Workflows7.Onc e your selec tions ar e made , click Create Local Refinemen t Regions and pr oceed on to the ne xt task. For mor e inf ormation ab out b odies of influenc e, see Body of Influenc e (p.214). If you need t o mak e adjustmen ts to an y of y our settings in this task, click Revert and E dit, mak e your changes and click Update, or click Canc el to cancel your changes . 6.3.6. Iden tifying C onstr uction S urfaces For geometr ies tha t ha ve pr imitiv e constr uction sur faces (e .g., capping sur faces, or c ylindr ical sur faces for mo ving r eference frames) alr eady defined as par t of the C AD mo del, you c an use the Iden tify Constr uction S urface task t o lo cate those p ortions of the geometr y and iden tify them as such so tha t Fluen t can handle them acc ordingly dur ing the meshing pr ocess.These sur faces ar e used t o fur ther decomp ose the main fluid in to multiple r egions , such as r egions ar ound a r otating fan f or a mo ving reference frame (MRF) simula tion. 177Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the F ault-t oler ant Meshing Workflow1.Specify a Name for the c onstr uction sur face, or use the default name ( construction-surface-1 ). 2.Choose an objec t in the list , or en ter text to filt er out the a vailable objec ts in the list b efore selec ting an objec t. 3.Onc e your selec tions ar e made , click Iden tify C onstr uction S urfaces and pr oceed on to the ne xt task. If you need t o mak e adjustmen ts to an y of y our settings in this task, click Edit, mak e your changes and click Update, or click Canc el to cancel your changes . 6.3.7. Extracting E dge F eatures You c an use the Extract Edge F eatures task t o iden tify imp ortant geometr ic features in or der t o retain their fidelit y for y our simula tion and t o impr ove the in tegrity of the final sur face mesh. Onc e these imp ortant feature ar e iden tified , additional op erations ar e applied t o impr int them on to the final sur face mesh. Size controls c an also b e applied t o them t o refine the mesh on those f eatures. 1.Specify a Name for the sp ecific edge f eature objec t, or use the default name ( edge-group-1 ). 2.For the Extraction M etho d Using field , selec t the t echnique t o be used f or the f eature extraction. Choic es are Feature Angle ,Intersec tion L oops , or Sharp Angle . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 178Working With F luen t Guided Workflows3.In the Objec ts list, you c an cho ose an objec t in the list , or en ter text to filt er out the a vailable objec ts in the list b efore selec ting an objec t. 4.Depending on the e xtraction metho d, you will ha ve to pr ovide the f ollowing: •For the Feature Angle extraction metho d, specify the Feature Angle tha t you w ant to use as the threshold f or feature extraction. If the angle b etween t wo adjac ent geometr y fac et nor mals is mor e than this f eature angle v alue , then a f eature is e xtracted a t the shar ing edge . •For the Intersec tion L oops extraction metho d, specify the Intersec ted B y option tha t you w ant to use as the thr eshold f or feature extraction: either individually or collec tively.This is a f eature located a t the in tersec tion of t wo geometr y fac ets. For collec tively, only fac ets acr oss objec ts ar e consider ed. For individually , all fac ets ar e consider ed. 179Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the F ault-t oler ant Meshing Workflow•For the Sharp Angle extraction metho d, specify the Sharp Angle tha t you w ant to use as the thr eshold for feature extraction. If the angle b etween t wo adjac ent geometr y fac et nor mals is mor e than this shar p angle v alue , then a f eature is e xtracted a t the shar ing edge .The default angle is 110 degr ees, in- dicating tha t these sur faces ha ve a v ery shar p angle b etween them. You c an define mor e refined siz e controls on them and also apply sp ecial op erations on these objec ts to force shar ing no des of the final surface mesh on to the geometr y. Figur e 6.26: An Example of A ddr essing S harp A ngles - C AD G eometr y Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 180Working With F luen t Guided WorkflowsFigur e 6.27: An Example of A ddr essing S harp A ngles - F inal M esh Figur e 6.28: Sharp A ngles With and Without the Z ones S epar ated B y Face To force the shar ing no des, the geometr y fac e zones need t o be separ ated a t the shar p angle edge . Selec t fac e zones p er par t for tha t objec t. 181Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the F ault-t oler ant Meshing Workflow5.Onc e your selec tions ar e made , click Extract Edge F eatures and pr oceed on to the ne xt task. If you need t o mak e adjustmen ts to an y of y our settings in this task, click Revert and E dit, mak e your changes and click Update, or click Canc el to cancel your changes . 6.3.8. Adding Thick ness t o Your G eometr y Some p ortions of an imp orted geometr y ma y not ha ve a thick ness (such as a baffle , or other in terior wall, for instanc e), and ma y be imp ortant or r elevant to your simula tion. A mor e refined sur face mesh can b e gener ated if all imp ortant and r elevant asp ects of the geometr y ha ve a c ertain thick ness . Not all p ortions of a geometr y requir e a thick ness . However, if it has no thick ness , and is imp ortant for your simula tion, and c ontains an adequa te numb er of qualit y geometr y fac ets, then y ou c an use the Add Thick ness task t o define a thick ness t o tha t portion of the geometr y.The geometr y is thick ened in the nor mal dir ection of the fac ets.You ma y want to reverse the fac et nor mal dir ection (see Manip- ulating B oundar y Zones (p.308)) before applying this op eration. 1.Specify a Name for the z ero thick ness geometr y, or use the default name ( face_group ). 2.Choose whether t o Selec t By the objec t name or the z one name in the list b elow. •If you Selec t By zones , in the Zones list, you c an cho ose a z one in the list , or en ter text to filt er out the available z ones in the list b efore selec ting a z one . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 182Working With F luen t Guided Workflows•If you Selec t By objec t, in the Objec ts list, you c an cho ose an objec t in the list , or en ter text to filt er out the a vailable objec ts in the list b efore selec ting an objec t. 3.Specify the Offset D istanc e tha t you w ant to use as the distanc e for the z ero thick ness geometr y.The geometr y will b e thick ened b y this v alue . 4.Onc e your selec tions ar e made , click Add Thick ness and pr oceed on to the ne xt task. If you need t o mak e adjustmen ts to an y of y our settings in this task, click Edit, mak e your changes and click Update, or click Canc el to cancel your changes . The f ollowing illustr ations demonstr ate some e xamples of r equir ing thick ness: 183Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the F ault-t oler ant Meshing Workflow6.3.9. Creating P orous Regions If your geometr y contains some r egions wher e porous media is pr esen t and y ou need t o simula te flo w through those p orous r egions , you c an use the Create Porous Regions task t o define p ortions of y our geometr y tha t will e xhibit p orous b ehavior in the flo w field . Figur e 6.29: An Example of a P orous Region Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 184Working With F luen t Guided WorkflowsFigur e 6.30: An Example of a P orous Region: Fins and Tubes in a H eat Exchanger Simula ting the pr essur e dr op of the fluid passing thr ough a p orous media r equir es a separ ate region. This separ ate porous r egion r equir es a v ery course and str uctured mesh. The Create Porous Regions task c an b e used t o gener ate such a mesh, which is used f or rectangular-shap ed r egions . 1.Specify a Name for the p orous r egion, or use the default name ( porous-region ). 2.Choose whether the Specify lo cation b y field is set t o Node S elec tion or Position S elec tion . 3.Use the r ight mouse butt on t o selec t four p oints in the gr aphics windo w to define the p orous r egion (P1, P2, P3, and P4). Their c oordina tes will b e list ed in the table in the task. Figur e 6.31: The P oints of a P orous Region 4.Specify a v alue either f or the Cell S ize Between P1 and P2 or the Numb er of C ells. 5.Specify a v alue either f or the Cell S ize Between P1 and P3 or the Numb er of C ells. 6.Specify a v alue either f or the Cell S ize Between P1 and P4 or the Numb er of C ells. 185Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the F ault-t oler ant Meshing Workflow7.Specify a v alue f or the Buff er S ize Ratio along with the Buff er S ize.There are two ad vantages f or ha ving a buff er zone: •The wr app er will not det ect the inlet or outlet of the c ore, which will a void z one r ecovery issues , mak ing for a much cleaner r ezoning of the wr app er sur faces. •The macr o-based hea t exchanger mo del in the F luen t solv er do es not allo w mesh in terfaces a t the in- let/outlet of the c ore.With the buff er la yer, the inlet and outlet ar e conformal, and the buff er can b e very thin (f or e xample , 1 to 2 mm). Figur e 6.32: The Buff er S ize for a P orous Region 8.Onc e your selec tions ar e made , click Create Porous Region and pr oceed on to the ne xt task. The final cell z one f or the p orous r egion will b e created. Fluen t will also cr eate a geometr y objec t for all tr iangula ted bounding fac es. If you need t o mak e adjustmen ts to an y of y our settings in this task, click Revert and E dit, mak e your changes and click Update, or click Canc el to cancel your changes . 6.3.10. Iden tifying Regions In comple x geometr ies, ther e could b e hundr eds or thousands of r egions r anging in v arious siz es, however, much of the time , you ar e only in terested in only a f ew r egions . Use the Iden tify Regions task t o pinp oint sp ecific r egions in y our imp orted geometr y, such as a v ehicle in an e xternal flo w simula tion. Here, you ar e positioning sp ecific p oints in the domain wher e certain objec ts of in terest can b e iden tified and classified f or la ter use in y our simula tion. In most c ases , ther e is not a single objec t tha t defines a r egion. Such r egions , such as most fluids and some v oids , can only b e iden tified using a sp ecific p oint (also r eferred t o as a mat erial point). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 186Working With F luen t Guided WorkflowsFigur e 6.33: Iden tifying a F luid Region in the Wake Behind a C ar Note Material p oints can also b e plac ed inside an y additional r egions tha t will b e created as a result of the dec omp osition of the main fluid r egion b y constr uction sur faces (see Iden tifying Constr uction Sur faces (p.177)). If ma terial p oints ar e not plac ed inside an y of the dec omp osed regions , these r egions will b e aut oma tically iden tified and named acc ording t o the name of the c onstr uction sur face. For e xample , if y ou ha ve iden tified a c onstr uction sur face in your w orkflow, named fan_mrf , any dec omp osed r egions cr eated fr om this c onstr uction surface and which neighb ors an y user-defined r egions , will b e aut oma tically named as fan_mrf-1 ,fan_mrf-2 , etc. For the Would y ou lik e to iden tify an y fluid or v oid r egion(s)? field , keep the default v alue of yes if your mo del r equir es y ou t o sp ecify an y fluid or v oid r egions using the f ollowing st eps. Other wise , selec t no, click Update and pr oceed t o the ne xt task. 1.Specify a Name for the r egion, or use the default name ( fluid-region-1 ).The default name changes dep ending on the assigned Region Type. 2.For Define L ocation U sing , selec t Centroid of O bjec ts to calcula te the p osition of the r egion based on the c entroid of the selec ted objec t(s), or selec t Numer ical Inputs to assign sp ecific c oordina tes to a par- ticular r egion. 3.Choose a Region Type for the r egion (either fluid or void). 187Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the F ault-t oler ant Meshing Workflow4.For the Link t o Constr uction S urface(s) field , keep the default v alue of no for most c ases in volving a singular fluid r egion. If, however, you mean t o iden tify an additional fluid r egion tha t is either inside or adjac ent to a c onstr uction sur faces, then set this v alue t o yes in or der t o pr operly mesh the additional fluid r egion acc ordingly (tha t is, using a sur face mesh). 5.Choose whether t o Selec t By the objec t name or the z one name in the list b elow. •If you Selec t By objec t, in the Objec ts list, you c an cho ose an objec t in the list , or en ter text to filt er out the a vailable objec ts in the list b efore selec ting an objec t. •If you Selec t By zones , in the Zones list, you c an cho ose a z one in the list , or en ter text to filt er out the available z ones in the list b efore selec ting a z one . 6.Use the View E xac t Coordina tes field t o see the sp ecific c oordina te values f or the r egion's iden tified location. 7.Onc e your selec tions ar e made , click Iden tify Regions and pr oceed on to the ne xt task. If you need t o mak e adjustmen ts to an y of y our settings in this task, click Revert and E dit, mak e your changes and click Update, or click Canc el to cancel your changes . Note If you ha ve pr eviously defined r egions based on sp ecific meshing objec ts tha t you sub- sequen tly r emo ve or r ename (f or e xample , in the Imp ort CAD and P art Managemen t task), you ma y need t o revert this task in or der t o refresh the list of meshing objec ts available f or y our r egion definition. Fluen t will pr ompt y ou if the list needs t o be re- freshed . 6.3.11. Defining L eak age Thresholds Onc e you ha ve defined all of y our objec ts in the Imp ort Geometr y and P art Managemen t task, it's always recommended t o mak e sur e tha t ther e ar e no lar ge par ts missing and tha t all the par ts fit t o- gether w ell. For instanc e, an imp orted c ar geometr y ma y be missing a lar ge par t (such as a do or), resulting in a lar ge hole and c ausing p otential flo w leak age in to the c abin. There ma y also b e potential imp erfections in the geometr y (for e xample , missing b olts, missing sealan ts, etc.), resulting in other , medium siz ed holes .These holes ma y be lar ger than an y of y our initial lo cal siz e controls, resulting in leaks tha t need t o be closed . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 188Working With F luen t Guided WorkflowsAny missing , misaligned par ts, or small imp erfections will lead t o leak ages tha t need t o be iden tified and closed using this task. For the Would y ou lik e to close an y leak ages f or y our r egion(s)? field , selec t yes if y our mo del r e- quir es y ou t o lo cate and addr ess an y leak age issues using the f ollowing st eps. Other wise , if y our model do es not ha ve an y leak age issues t o addr ess, keep the default of no, click Update and pr oceed to the ne xt task. 1.Specify a Name for the leak age thr eshold c ontrol, or use the default name ( leakage-1 ). 2.Use the Regions list t o selec t the r egion tha t requir es a leak age thr eshold c ontrol. 3.Specify a Maximum L eak age S ize. 4.Selec t the Preview Leak ages butt on t o see if ther e are an y leak ages pr esen t or not. If you c an see leak ages occur ring b etween r egions , adjust the Maximum L eak age S ize and click the Preview Leak ages butt on again t o reconstr uct the gener alized mesh. Repeat as needed un til all leaks ha ve been r esolv ed. Figur e 6.34: Iden tifying P otential L eak ages Within a C ar 189Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the F ault-t oler ant Meshing Workflow5.Use a Leak age P lane controls t o assess the in terior of y our geometr y to help y ou t o pr eview and iden tify leak ages . •Use the slider t o adjust the Location acc ordingly t o visualiz e an y leak ages . •Specify the Orientation as either in the X,Y, or Z direction. •Use the Flip option t o flip the or ientation of the clipping plane t o suit y our r equir emen ts. 6.Onc e your selec tions ar e made , click Define L eak age Threshold and pr oceed on to the ne xt task. If you need t o mak e adjustmen ts to an y of y our settings in this task, click Revert and E dit, mak e your changes and click Update, or click Canc el to cancel your changes . 6.3.12. Updating Your Region S ettings You c an r eview and up date the pr operties of an y defined r egions using the Update Region S ettings task. Any aut oma tically det ected r egions will b e filled with t etrahedr al cells, designa ted as fluid , and given a single la yer of pr ism c ells f or the b oundar y layer. 1.The Main F luid field indic ates the name of the pr imar y fluid r egion f or y our simula tion. 2.Use the Displa yed Regions field t o indic ate ho w your r egions will b e displa yed in the table .You can selec t All Regions ,Objec t Based Regions , or Iden tified Regions .This c an b e helpful when you ha ve a lar ge numb er of r egions . 3.(optional) U se the Filter butt on t o filt er the table c ontents based on a par ticular c olumn. 4.Rename an y region Name by double-click ing the lab el in the table and en tering a new name . 5.Choose a r egion Type as either fluid ,solid , or void. Multiple r egions c an b e assigned a sp ecific t ype all a t onc e by selec ting them in the table , right- click, and selec t Set Type in the c ontext menu , then designa te a t ype for the selec ted r egions dir ectly in the menu . 6.Assign the Extraction M etho d to either wrap or surface mesh . Multiple r egions c an b e assigned a sp ecific e xtraction metho d all a t onc e by selec ting them in the table , right-click, and selec t Set E xtraction M etho d in the c ontext menu , then designa te an e xtrac- tion metho d for the selec ted r egions dir ectly in the menu . Fluid r egions tha t are within or adjac ent to constr uction sur faces (using the Link t o Constr uction Surface(s) field) will aut oma tically use the surface mesh extraction metho d. 7.Choose a Volume F ill as either none ,tet, or hexcore, or k eep the default setting . Multiple r egions c an b e assigned a sp ecific v olume fill t ype all a t onc e by selec ting them in the table , right-click, and selec t Set Volume F ill in the c ontext menu , then designa te a v olume fill t ype for the selec ted r egions dir ectly in the menu . The options a vailable f or Volume F ill dep end up on the selec ted Type(s). For a selec ted fluid region, for e xample , you c an only cho ose fr om tet or hexcore for the Volume F ill option. However, if y ou selec t multiple r egions , such as a fluid and a solid region, no options ar e available sinc e ther e ar e no v olume fill t ypes tha t can b e applied t o both r egion t ypes. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 190Working With F luen t Guided Workflows8.Specify a v alue f or the Leak age S ize, or k eep the default v alue . Multiple r egions c an b e assigned a sp ecific leak age siz e value all a t onc e by selec ting them in the table , right-click, and selec t Set L eak age S ize in the c ontext menu , then sp ecify a v alue f or the selec ted r egions dir ectly in the menu . 9.When y ou ar e sa tisfied with the r egion assignmen ts, click Update Region S ettings . If you need t o mak e adjustmen ts to an y of y our settings in this task, click Revert and E dit, mak e your changes and click Update, or click Canc el to cancel your changes . 10.One or mor e regions c an b e visualiz ed all a t onc e by selec ting them in the table , right-click, and selec t Draw S elec tions in the c ontext menu . 11.Onc e all r egions ha ve been up dated, proceed t o the ne xt step in the w orkflow. 6.3.13. Choosing M esh C ontrol Options The Choose M esh C ontrol Options task allo ws you t o pick and cho ose v arious means of gener ating and r efining the mesh in y our simula tion. 1.Specify ho w you w ould lik e to manage y our siz e controls. •Selec t Create New to star t with a new c ollec tion of siz e controls. •Selec t Read e xisting siz e control file to add y our siz e controls based on those alr eady defined in a size control file (*.szcontrol ), specified using the Size Control F ile field . 2.If you ar e creating new siz e controls, you need t o sp ecify the na ture of the siz e controls y ou ar e going t o use. •Selec t Default to popula te your siz e controls with default settings , based on the numb er of objec ts in your mo del. Using this option and up dating the task will add a Setup S ize Controls task t o the w orkflow, along with as man y siz e controls as ther e are objec ts, each using the same default settings . •Selec t Custom to popula te as man y siz e controls as y ou need using y our o wn cust omiz ed settings . Using this option and up dating the task will add a single Setup S ize Controls task t o your w orkflow, wher e you cr eate as man y siz e controls as y ou r equir e. For mor e inf ormation, see (see Setting U p Size Controls (p.192)) 3.Click Advanc ed Options to acc ess additional c ontrols pr ior t o performing this task. Options include: •For the Apply quick edge pr oximit y? prompt , selec t Yes to sp eed up the c alcula tion and r educ e memor y requir emen ts when using a pr oximit y siz e func tion with geometr ies ha ving a v ery lar ge numb er of small f eature edges . •Specify a v alue f or the Solid/F luid S ize Ratio field , or k eep the default. This is the r atio of the actual siz e of the solid and the ac tual siz e of the fluid , used f or solid meshing . For e xample , if this r atio is 1.5 and the fluid siz e is 1, then the solid siz e will b e 1.5. •Specify a v alue f or the Wrap/T arget S ize Ratio field , or k eep the default. This is the r atio of the initial wrap siz e and the lo cal tar get siz e. For e xample , if this r atio is 0.67 and the tar get siz e is 1, then the initial wr ap siz e will b e 0.67. 191Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the F ault-t oler ant Meshing Workflow4.Onc e your selec tions ar e made , click Choose M esh C ontrol Options and pr oceed on to the ne xt task. If you need t o mak e adjustmen ts to an y of y our settings in this task, click Edit, mak e your changes and click Update, or click Canc el to cancel your changes . 6.3.14. Setting U p Size Controls Use the Setup S ize Controls task t o cr eate individual sizing c ontrols f or y our mesh. For e very siz e control tha t you cr eate, it is added t o the w orkflow as a subtask of the Setup S ize Controls task. 1.Specify a Name for the mesh sizing c ontrol, or use the default name ( size-control-1 ). 2.Choose an option f or the Size Func tions field . Available options ar e: •Choose the curvature size func tion tha t comput es edge and fac e siz es using their siz e and nor mal angle par amet ers. •Choose the proximit y size func tion tha t comput es edge and fac e siz es in ‘gaps ’ using the sp ecified minimum numb er of elemen t layers. •Choose the soft size func tion tha t enables y ou t o set the maximum siz e on the selec ted z one , while the sp ecified gr owth r ate from the defined siz e influenc es the siz e on adjac ent zones . •Choose the boi size func tion enables y ou t o sp ecify a b ody of influenc e (tha t is, a refinemen t region for the sizing c ontrol). For additional inf ormation, see Size Functions and Sc oped S izing (p.207). 3.Specify a v alue f or the Minimum S ize for the siz e control when using the curvature or proximit y size func tion t ypes. 4.Specify a v alue f or the Maximum S ize for the siz e control. 5.Specify a v alue f or the Growth R ate for the siz e control. 6.Specify a v alue f or the Cells P er G ap when using the proximit y size func tion t ype. Note tha t for pr oximit y size func tions , the numb er of c ells p er gap c an b e a r eal v alue , with a minimum v alue of 0.1. See Proxim- ity (p.209) for mor e inf ormation. 7.Specify a v alue f or the Curvature Normal A ngle when using the curvature size func tion t ype. 8.If applic able , deselec t Ignor e Self when using the proximit y size func tion t ype. By default ,Ignor e Self is enabled , such tha t the pr oximit y between t wo fac ets b elonging in a single fac e zone will b e ignor ed, avoiding unnec essar y over-refinemen t. 9.Choose an option in the Scope Proximit y To field , wher e the siz e controls c an b e sc oped t o edges ,faces, or to both faces and edges . Note tha t if y ou selec t faces-and-edges , you c an only selec t objec ts. 10.Choose whether t o Selec t By the objec t name or the z one name in the list b elow. •If you Selec t By objec t, in the Objec ts list, you c an cho ose an objec t in the list , or en ter text to filt er out the a vailable objec ts in the list b efore selec ting an objec t. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 192Working With F luen t Guided Workflows•If you Selec t By zones , in the Zones list, you c an cho ose a z one in the list , or en ter text to filt er out the available z ones in the list b efore selec ting a z one . Note tha t this option is not applic able when Scope Proximit y To is set t o faces-and-edges . 11.Selec t the Show S ize Box field t o visualiz e the siz e control's minimum and maximum siz es in the gr aphics windo w (in the f orm of r ed cub es). 12.Click Advanc ed Options to acc ess additional c ontrols pr ior t o performing this task. Options include: •Specify a v alue f or the Wrap M in S ize field . •Specify a v alue f or the Wrap M ax S ize field . •Selec t the Show Wrap S ize Box field t o visualiz e the wr ap's minimum and maximum siz es in the graphics windo w (in the f orm of r ed cub es). 13.Onc e your selec tions ar e made , click Setup S ize Controls and pr oceed on to the ne xt task. If you need t o mak e adjustmen ts to an y of y our settings in this task, click Revert and E dit, mak e your changes and click Update, or click Canc el to cancel your changes . 6.3.15. Gener ating the S urface M esh The Gener ate the S urface M esh task will close all the leak ages t o objec ts and v oid r egions and then gener ate only the sur face mesh. If requir ed, specify the Surface M esh Target S kewness , or k eep the default setting .This v alue is the target maximum sur face mesh qualit y, and is r ecommended t o be between 0.7 and 0.85. For Advanc ed Options , you c an: •Indic ate whether or not y ou w ant to sa ve intermedia te files . Selec t Yes if you w ant to sa ve files af ter each major op eration such as c omputing siz e field , wrapping , surface remesh, etc.This is useful when meshing lar ge mo dels so tha t you c an load those files of in terest dur ing the meshing pr ocess. •Indic ate whether or not y ou w ant to separ ate the sur face mesh. Selec t Yes if you w ant to ha ve the final surface mesh t o be view ed as separ ated z ones . 193Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the F ault-t oler ant Meshing Workflow•Indic ate whether or not y ou w ant to separ ate contact pairs b etween fluids and solids in the surface mesh. •Indic ate whether or not y ou w ant to perform solid meshing using par allel sessions . Selec t Yes and indic ate the Maximum N umb er of S essions .The numb er of par allel sessions tha t are used will dep end up on the numb er of solid objec ts tha t need t o be meshed . For e xample , if y ou in- dicate four par allel sessions , and y ou w ant to mesh thr ee solid objec ts, then thr ee par allel ses- sions will b e used t o perform the solid meshing . If, however, you ha ve six solid objec ts tha t need t o be meshed , then the y will b e equally divided b etween the f our par allel sessions . Onc e your selec tions ar e made , click Gener ate the S urface M esh and pr oceed on to the ne xt task. If you need t o mak e adjustmen ts to an y of y our settings in this task, click Revert and E dit, mak e your changes and click Update, or click Canc el to cancel your changes . 6.3.16. Setting U p Boundar y Layer C ontrols For most fluid r egions , the b oundar y layer flo w along the w alls of the geometr y is b est c aptur ed using specializ ed b oundar y layer elemen ts within the v olume mesh (also c alled prisms or inflation la yers). Prism elemen ts ar e gener ated on the w alls of the geometr y tha t fac e the fluid r egion (t ypic ally r eferred to as “wetted” walls). You c an use the Setup B oundar y Layers task t o assign diff erent regions t o ha ve their o wn b oundar y layer controls.When a b oundar y layer is assigned t o a r egion, all fac e zones asso- ciated with tha t region will b e assigned those settings . Any zone-sp ecific settings (e xcept the numb er of la yers) defined in the Prisms dialo g ar e respected. For mor e inf ormation ab out pr isms , see Gener ating Prisms (p.367) and Growth Options f or Z one-S pecific P risms (p.373). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 194Working With F luen t Guided WorkflowsFor the Would y ou w ant to add b oundar y la yers t o fluid r egions? field , selec t yes if y our mo del requir es y ou t o lo cate and addr ess an y boundar y layers using the f ollowing st eps. Other wise , if y our model do es not r equir e you t o ha ve boundar y layers, keep the default of no, click Update and pr oceed to the ne xt task. 1.Specify a Name for the b oundar y layer control, or use the default name ( prism-1 ). 2.Choose an Offset M etho d Type.The off set metho d tha t you cho ose det ermines ho w the mesh c ells closest t o the b oundar y are gener ated. See Offset D istanc es (p.381) for mor e inf ormation. Choic es include: •asp ect-ratio: allo ws you t o control the asp ect ratio of the b oundar y layer cells (or pr ism c ells) tha t are extruded fr om the base b oundar y zone . Specify the Aspect Ratio tha t you w ant to use f or the b oundar y layer.The asp ect ratio is defined as the r atio of the pr ism base length t o the pr ism la yer heigh t. •last-r atio: allo ws you t o sp ecify the c ell siz e ratio b etween the last la yer and base c ell of the b oundar y layer cells (or pr ism c ells) tha t are extruded fr om the base b oundar y zone . –You c an sp ecify a v alue f or the First H eigh t, which c orresponds t o the heigh t of the first la yer of c ells in the b oundar y layer. –You c an sp ecify a v alue f or the Last R atio P ercentage . 195Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the F ault-t oler ant Meshing Workflow•unif orm: allo ws you t o gener ate every new no de (child) t o be initially the same distanc e away from its parent no de (tha t is, the c orresponding no de on the pr evious la yer, from which the dir ection v ector is pointing). 3.Specify a v alue f or the Growth R ate.This v alue det ermines the r elative thick ness of adjac ent infla tion layers. As you mo ve away from the fac e to which the infla tion c ontrol is applied , each succ essiv e layer is appr oxima tely one gr owth r ate fac tor thick er than the pr evious one . 4.Use the Region list t o selec t the r egion tha t requir es a b oundar y layer control. 5.Onc e your selec tions ar e made , click Setup B oundar y Layers and pr oceed on to the ne xt task. If you need t o mak e adjustmen ts to an y of y our settings in this task, click Revert and E dit, mak e your changes and click Update, or click Canc el to cancel your changes . 6.3.17. Gener ating the Volume M esh The Gener ate the Volume M esh task will p erform v arious op erations and gener ate the v olume mesh. If requir ed, specify the Volume M esh Target S kewness , or k eep the default setting .This v alue is the target maximum v olume mesh qualit y, and is r ecommended t o be ar ound 0.96. If you w ould lik e to review and change the v olume meshing t echnique f or y our r egion(s), you c an selec t the Edit Volume F ill S ettings option. This displa ys a tabular o verview of the simula tion's v olume r e- gion(s) and their mesh settings (f ormer ly set in the Update Region S ettings task), tha t you c an change accordingly b efore finally gener ating the v olume mesh. Onc e your selec tion is made , click Gener ate the Volume M esh and pr oceed on to the ne xt task. If you need t o mak e adjustmen ts to an y of y our settings in this task, click Revert and E dit, mak e your changes and click Update, or click Canc el to cancel your changes . From this task, if y ou need t o addr ess an y sur face contact issues , you c an add a Separ ating C ontacts task t o your w orkflow (see Separ ating C ontacts (p.196)). 6.3.18. Separ ating C ontacts Onc e you ha ve complet ed the v olume mesh, you c an add the Separ ate Contacts task t o addr ess an y issues with c ontact sur faces and separ ate an y contacts b etween fluid c ell z ones (fluid r egions). 1.Use the Separ ate Contacts field t o enable or disable the abilit y to separ ate an y existing c ontacts between surfaces. 2.Onc e your selec tions ar e made , click Separ ate Contacts to up date the task. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 196Working With F luen t Guided WorkflowsUpon c ompletion, the task will gener ate a Scheme file c alled out_solver_f2f_set_nci.scm . This Scheme file c an b e loaded in to the F luen t solv er af ter mesh sc aling ( File > Read > Scheme ), which will aut oma tically set the mesh in terfaces. If you need t o mak e adjustmen ts to an y of y our settings in this task, click Edit, mak e your changes and click Update, or click Canc el to cancel your changes . 197Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the F ault-t oler ant Meshing WorkflowRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 198Chapt er 7: CAD A ssemblies The CAD A ssemblies mo de off ers additional t ools f or imp orted C AD da ta in F luen t Meshing .The CAD Assemblies tree r epresen ts the C AD tr ee as it is pr esen ted in the C AD pack age in which it w as cr eated. All sub-assembly le vels fr om the C AD ar e main tained on imp ort in F luen t Meshing . Advantages of using the C AD A ssemblies tr ee include the f ollowing: •The C AD assemblies tr ee enables fast er visualiza tion which sa ves time in par t managemen t for lar ge, comple x models c ompr ising multiple assemblies . •It enables r e-imp orting or up dating of selec ted par ts or b odies using diff erent fac eting qualities and t opology represen tations fr om a neutr al da tabase file . •Geometr y and mesh objec ts can b e easily cr eated f or only those assemblies , par ts, or b odies tha t are needed for the analy sis. Other assemblies , par ts, or b odies c an b e simply suppr essed . •The geometr y and mesh objec ts ar e link ed t o the c orresponding C AD objec ts (which ar e then lo cked), enabling quick design changes and up dates. •Labels c an b e assigned t o en tities , and these ar e pr eser ved thr oughout the objec t-based meshing w orkflow in Fluen t Meshing . The use of C AD assemblies f or C AD imp ort in F luen t Meshing is descr ibed in the f ollowing sec tions . 7.1. CAD A ssemblies Tree 7.2.Visualizing C AD En tities 7.3. Updating C AD En tities 7.4. Manipula ting C AD En tities 7.5. CAD A ssociation 7.1. CAD A ssemblies Tree The CAD A ssemblies tree is cr eated when the Create CAD A ssemblies option is selec ted f or C AD imp ort. It represen ts the C AD tr ee as it is pr esen ted in the C AD pack age in which it w as cr eated. All sub-assembly levels fr om the C AD ar e main tained on imp ort in F luen t Meshing . To cr eate the C AD A ssemblies tr ee on imp ort, enable Create CAD A ssemblies in the Objec t Creation group b ox in the CAD Options dialo g box.The C AD objec t and z one gr anular ity can b e sp ecified in the Objec t Creation group b ox.You c an cho ose t o cr eate one C AD objec t per par t,body, CAD file or selec tion imp orted. Similar ly, you c an cho ose t o cr eate one C AD z one p er body,face, or objec t imp orted. Tip Imp orting C AD objec ts b y body giv es an ideal C AD assemblies tr ee, with the or iginal sub- assemblies pr eser ved. 199Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.The C AD assemblies tr ee includes individual C AD assemblies or sub-assemblies imp orted in F luen t Meshing .The en tity at the highest le vel is also r eferred t o as the root no de. The C AD en tities in the tr ee ar e categor ized as comp onen ts and bodies . Comp onen ts represen t an assembly , sub-assembly , or par t in the or iginal C AD pack age, while b odies ar e the basic en tities in the CAD assemblies tr ee which include C AD z ones .You c an also set up lab els f or the C AD z ones , if requir ed. Named S elec tions ar e also imp orted as lab els.These lab els ar e pr eser ved thr oughout the objec t-based meshing w orkflow in F luen t Meshing . In addition t o the c ontext-sensitiv e menus , you c an manage the C AD en tities using hotk eys or onscr een tool butt ons.Tools e xist f or visualizing the C AD en tities , for op erations such as up dating and mo difying the C AD en tities , creating and/or mo difying geometr y or mesh objec ts, and tr ee selec tion options . See Appendix C: Shortcut Ke ys (p.527) for mor e inf ormation. Note When w orking with C AD A ssemblies , certain meshing r ibbon t ools ar e disabled . At the global CAD A ssemblies level, you c an use the menu options t o dr aw or delet e all the assemblies imp orted, and obtain the lo cations of the r eferenced FMDB files .The Tree sub-menu c ontains options for na viga tion and selec tions in the tr ee. 7.1.1. FMDB F ile 7.1.2. CAD En tity Path 7.1.3. CAD A ssemblies Tree Options 7.1.1. FMDB F ile The FMDB file (*.fmdb) is a C AD neutr al file tha t is cr eated when the C AD A ssemblies ar e created during C AD imp ort.This file enables quick r e-imp ort of the C AD da ta with changes t o the fac eting qualities and/or t opology represen tations . •When imp orting a single file , the FMDB file is cr eated in the f older c ontaining the C AD file and has the same name as the file imp orted. •When imp orting multiple files , the FMDB file is cr eated in the f older c ontaining the C AD files and is named multiple.fmdb by default. You c an sp ecify an appr opriate name in the FMDB L ocation dialo g box when pr ompt ed. The menu a t the global C AD A ssemblies le vel enables y ou t o obtain a list of the r eferenced FMDB files . Selec t Referenc ed FMDB in the menu t o op en the Referenc ed FMDB files dialo g box containing the list of FMDB files . 7.1.2. CAD E ntity Path All CAD en tities and lab els in the C AD A ssemblies tr ee ar e referred t o by their pa th.The pa th is used in commands in the cad-assemblies menu (see cad-assemblies/ for details). To see the pa th, right-click the C AD en tity in the tr ee and selec t Tree → Show P ath. Examples of the C AD en tity pa th: |assembly.agdb|component_1 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 200CAD A ssemblies|assembly.agdb|component_1|body_1 |assembly.agdb|body_1|label 7.1.3. CAD A ssemblies Tree Options The Tree menu c ontains options tha t control the app earance of the C AD A ssemblies tr ee.These options can b e used t o selec t or deselec t the C AD objec ts and z ones in the tr ee, expand or c ollapse the tr ee branches , and also delet e suppr essed or lo cked C AD objec ts. At the global CAD A ssemblies level: •The Selec tion H elper enables y ou t o selec t or deselec t CAD objec ts or lab els in the tr ee based on the specified Name P attern.You c an cho ose cad-objec ts,leaf-c ad-objec ts,non-leaf-c ad-objec ts, or label in the Filter list. •The Selec t Next Level option selec ts the C AD assemblies or objec ts at the ne xt lower le vel. •The Collapse A ll option c ollapses the tr ee to the le vel selec ted. •The Delet e Locked/S uppr essed option delet es all lo cked or suppr essed C AD assemblies or objec ts. •The Rest ore Delet ed option r estores pr eviously delet ed C AD assemblies or objec ts. At the c omp onen t level: •The Selec tion H elper enables y ou t o selec t CAD objec ts or lab els in the tr ee based on the sp ecified Name Pattern.You c an cho ose leaf-c ad-objec ts,non-leaf-c ad-objec ts, or label in the Filter list. •The Selec t Next Level option selec ts the C AD assemblies or objec ts at the ne xt lower le vel. •The Expand A ll option e xpands the tr ee to sho w all subsequen t levels (C AD objec ts and lab els, if applic able). Similar ly, the Collapse A ll option c ollapses the tr ee to the le vel selec ted. •The Show P ath option pr ints the C AD en tity pa th in the c onsole . •The Suppr ess O ther option suppr esses all other C AD en tities a t the same le vel. •The Selec t Associated O bjec ts selec ts geometr y/mesh objec ts asso ciated with the selec ted c omp onen t. At the b ody level: •The Show P ath option pr ints the C AD en tity pa th in the c onsole . •The Suppr ess O ther option suppr esses all other C AD en tities a t the same le vel. •The Selec t Associated O bjec ts selec ts geometr y/mesh objec ts asso ciated with the selec ted b ody. At the lab el le vel: •The Selec t All Parent option selec ts all the par ent CAD en tities in the tr ee. •The Show P ath option pr ints the C AD en tity pa th in the c onsole . 201Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.CAD A ssemblies Tree7.2. Visualizing C AD E ntities CAD en tities c an b e displa yed using the options a vailable f or the C AD A ssemblies tr ee: •The global menu f or the CAD A ssemblies contains an option t o dr aw all the C AD assemblies imp orted. •The menu f or individual c omp onen ts and b odies c ontains an option t o dr aw the selec ted en tity.You c an also use the additional options in the Draw Options menu t o add , remo ve, or highligh t the selec ted en tity in the displa y.You c an also dr aw the unlab eled z ones f or the en tity selec ted. •The menu f or lab els c ontains an option t o dr aw the selec ted lab el.You c an also use the additional options in the Draw Options menu t o dr aw all lab els and add , remo ve, or highligh t the selec ted lab el in the displa y. You c an also dr aw the o verlapping z ones f or the lab el selec ted. The C AD en tities ar e displa yed using a diff erent color palett e to tha t used f or the geometr y/mesh objec ts. The z one and objec t selec tion filt ers also apply t o the C AD z ones and objec ts. Other visualiza tion t ools and shor tcuts ar e also applic able t o the C AD en tities .You c an use the shor tcut keys or onscr een t ools t o selec t visible en tities , deselec t all or the last selec ted en tity, hide/sho w en tities . You c an also use the Isola te tools t o isola te selec ted en tities in the displa y or limit the displa y to en tities based on ar ea/cur vature of the selec ted en tities . 7.3. Updating C AD E ntities The Update option enables r eimp orting the C AD en tities using new par amet ers. Selec t the C AD objec ts in the tr ee and selec t Update. Alternatively, selec t the C AD objec ts in the gr aphics displa y and click to op en the Update dialo g box. Tip Be sur e to clear the tr ee (using Ctrl+Y) before selec ting it ems t o up date. •You c an change the C AD z one gr anular ity, if requir ed. •Selec t the Tessella tion option and sp ecify the t essella tion c ontrols: –If you selec t the CAD F aceting option, you need t o sp ecify the Toler anc e for refinemen t and the Max Size in the CAD F aceting C ontrols group b ox.The default v alue f or Toler anc e is 0, which implies no tessella tion (fac eting) r efinemen t dur ing imp ort.The Max S ize enables y ou t o sp ecify a maximum fac et size for the imp orted mo del t o avoid v ery lar ge fac ets dur ing the file imp ort. –If you selec t the CFD S urface M esh option, you need t o sp ecify the minimum and maximum fac et siz es (Min S ize,Max S ize), and the cur vature nor mal angle t o be used f or refining the sur face mesh based on the under lying cur ve and sur face cur vature.You c an optionally use the edge pr oximit y siz e func tion f or creating the sur face mesh, based on the numb er of c ells p er gap sp ecified .You c an also cho ose t o sa ve a siz e-field file based on these defined par amet ers (i.e ., Min S ize,Max S ize,Curvature Normal A ngle ,Cells Per G ap). Note tha t for pr oximit y siz e func tions , the numb er of c ells p er gap c an b e a r eal v alue , with a minimum of 0.1 (see Proximit y (p.209) for mor e inf ormation). Alternatively, you c an use a pr eviously sa ved siz e-field file t o cr eate the sur face mesh b y enabling Use S ize Field F ile. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 202CAD A ssemblies•You c an cho ose t o imp ort edge z ones fr om the C AD en tities . Specify an appr opriate value f or Angle . 7.4. Manipula ting C AD E ntities CAD managemen t op erations ar e available fr om the tr ee menus as w ell as thr ough the gr aphics ic ons and hot-k eys. 7.4.1. Creating and M odifying G eometr y/M esh O bjec ts 7.4.2. Managing Lab els 7.4.3. Setting C AD En tity States 7.4.4. Modifying C AD En tities 7.4.1. Creating and M odifying G eometr y/M esh O bjec ts The Objec t menu c ontains options f or cr eating geometr y/mesh objec ts fr om the C AD en tities and modifying e xisting objec ts. Selec t the C AD en tities in the tr ee and then cho ose the appr opriate menu option. Alternatively, selec t the C AD objec ts in the gr aphics displa y and selec t the option fr om the CAD Tools. •Use the Create ( ) option t o create a new geometr y/mesh objec t.The Create Objec t dialo g box contains options f or cr eating a geometr y or mesh objec t based on the tr ee selec tions . Specify the Objec t Name , Objec t Type (geom or mesh), and the Cell Z one Type (solid , fluid , or dead). In c ase of multiple selec tions , you c an cho ose t o create One O bjec t per C AD O bjec t Selec tion .You c an also cho ose t o retain the C AD zone gr anular ity by enabling Keep C AD Z ones G ranular ity. Note The C AD asso ciation will b e transf erred t o the objec ts when y ou cho ose t o retain the CAD z one gr anular ity for objec t creation. •Use the Add t o ( ) option t o add the selec ted C AD en tities t o an e xisting objec t.The Add t o O bjec t dialo g box contains a list of the cur rent objec ts. Selec t the objec t to be mo dified and click Add. When C AD en tities ar e added t o an objec t, the z ones ar e mer ged t o cr eate a single z one . If the C AD entities ha ve lab els defined: –Adding the en tities t o an objec t with no lab els defined will r esult in the lab eled z ones r etained as separ ate zones . –Adding the en tities t o an objec t with the same lab els defined will r esult in the lab els b eing mer ged , but retain the z ones r etained as separ ate zones . •Use the Replac e option ( ) to replac e an e xisting objec t with the selec ted C AD en tities .The Replac e Objec t dialo g box contains a list of the cur rent objec ts. Selec t the objec t to be replac ed and click Replac e. 203Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Manipula ting C AD En tities7.4.2. Managing L abels You c an set up lab els f or the C AD z ones , if requir ed. Named S elec tions ar e also imp orted as lab els. These lab els ar e pr eser ved thr oughout the objec t-based meshing w orkflow in F luen t Meshing . You c an manage lab els f or C AD en tities using the Manage L abels dialo g box. Selec t the C AD z ones in the displa y using the z one selec tion filt er ( ) and then click Manage L abels ( ). •Use the Create/A dd lab el option t o create a new lab el for the C AD z ones selec ted and click Add. If Remo ve CAD Z ones fr om G raphics is enabled (default), the selec ted C AD z ones will b e remo ved fr om the displa y after the lab el is cr eated. •Use the Create/A dd lab el option t o add an e xisting lab el to the C AD z ones selec ted. Selec t the lab els fr om the list and click Add. If Remo ve CAD Z ones fr om G raphics is enabled (default), the selec ted C AD z ones will b e remo ved fr om the displa y after the z ones ar e added t o the lab el. •Use the Remo ve lab el option t o remo ve an e xisting lab el fr om the C AD z ones selec ted. Selec t the lab els from the list and click Remo ve. The Modify menu f or lab els c ontains options f or deleting and r enaming lab els. •Use the Delet e option t o delet e the selec ted lab els. •Use the Rename option t o rename the lab els.Specify the name in the Rename L abels dialo g box and click OK. In c ase of multiple selec tions , the sp ecified name will b e used , with a suitable inde x as suffix. For e xample , specifying a new lab el name wall will r esult in lab els wall.1 ,wall.2 , etc. 7.4.3. Setting C AD E ntity States The State menu f or the C AD en tities (c omp onen t or b ody) contains options f or setting the C AD en tity state. Locked CAD en tities ar e locked when c orresponding geometr y or mesh objec ts ar e created. Locked en tities cannot b e mo dified or used f or cr eating objec ts.This pr events the use of the same C AD en tity in multiple objec ts. To unlo ck an en tity, use the State → Unlock option. Suppr essed CAD en tities c an b e suppr essed if the y are not r equir ed f or the analy sis.You c an tr ansf er only nec essar y entities t o geometr y or mesh objec ts for meshing using the objec t-based w orkflow and suppr ess the r e- maining en tities . To suppr ess an en tity, use the State → Suppr ess option. Alternatively, selec t the C AD objec ts and click . To unsuppr ess an en tity, use the State → Unsuppr ess option. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 204CAD A ssemblies7.4.4. Modifying C AD E ntities The options in the Modify menu a t the C AD en tity (comp onen t or b ody) le vel enable mo difying the CAD en tities . Selec t the C AD en tities in the tr ee and then cho ose the appr opriate menu option. Altern- atively, selec t the C AD objec ts in the gr aphics displa y and selec t the option fr om the CAD Tools. •Use the Extract Edge Z ones option ( ) to extract the f eature edge z one f or the selec ted en tities . Specify the Angle in the Extract Edge Z ones dialo g box and click Create. •Use the Rename ( ) option t o rename the selec ted en tities . Specify the name in the Rename C AD Assemblies dialo g box (or the Rename E ntities dialo g box) and click OK. For multiple en tities , the sp ecified name will b e used , with a suitable inde x as suffix. For e xample , specifying a new name wall will r esult in entities wall.1 ,wall.2 , etc. •Use the Add P refix option t o add a pr efix t o the selec ted en tities . Specify the pr efix in the Prefix name dialo g box and click OK. 7.5. CAD A ssociation The CAD A ssociation menu f or geometr y/mesh objec ts contains options f or mo difying the selec ted objec ts based on the asso ciated C AD en tities .You c an also a ttach or detach the C AD en tities fr om the objec ts. •Use the Update from C AD option t o up date the geometr y/mesh objec ts based on changes t o the asso ciated CAD objec ts. •Use the Unlock C AD option t o unlo ck the C AD objec ts asso ciated with the selec ted geometr y/mesh objec ts. •Use the Selec t CAD option t o selec t the C AD objec ts asso ciated with the selec ted geometr y/mesh objec ts. •Use the Detach C AD option t o detach the C AD objec ts asso ciated with the selec ted geometr y/mesh objec ts. All asso ciation will b e remo ved and the geometr y/mesh objec ts will b e indep enden t of changes t o the C AD entities . •Use the Attach C AD option t o attach C AD objec ts to the selec ted geometr y/mesh objec ts. Selec t CAD objec ts to be asso ciated with the geometr y/mesh objec ts in the tr ee and click Confir m in the Attach C AD assemblies dialo g box.The selec ted geometr y/mesh objec ts will b e asso ciated with the C AD objec ts which will then be locked. •Use the Rest ore CAD option t o restore the geometr y/mesh objec t from the asso ciated C AD objec ts. 205Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.CAD A ssociationRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 206Chapt er 8: Size Func tions and Sc oped S izing Size Func tions and Scoped S izing provide c ontrol o ver ho w the mesh siz e is distr ibut ed on a sur face or within the v olume .They pr ovide accur ate sizing inf ormation f or the mesh distr ibution and pr ecise refinemen t control. Scoped sizing diff ers fr om siz e func tions in ho w the sizing c an b e asso ciated with objec ts or z ones , re- spectively. Scoped sizing ma y be applied t o mo del f eatures such as fac es, edges , face zone lab els or unreferenced fac e or edge z ones .You c an optionally selec t the t ype of objec t (geom, mesh) while ap- plying sc oped sizing . Scoped sizing c an b e defined on individual z one or objec t en tities b y selec ting from a list or using wildc ards (*). For c onvenienc e, your sc oped sizing definitions c an also b e sa ved t o a file (*.szcontrol ) which c an b e read in and r eused f or similar mo dels ha ving the same naming conventions . The siz e field is c omput ed based on the siz e func tions and/or sc oped sizing defined .You c an r emesh surfaces and edges based on the siz e field .The C utCell mesher also uses the siz e field t o refine the initial C artesian mesh. Imp ortant Size func tions c an b e comput ed only f or tr iangula ted z ones . For z ones c ompr ising non-tr ian- gular elemen ts, you c an tr iangula te the z ones manually b efore computing the siz e func tions . Alternatively, you c an use the c ommand triangulate-quad-faces? before computing the siz e func tions .This c ommand iden tifies the z ones c ompr ising non-tr iangular elemen ts and uses a tr iangula ted c opy of these z ones f or c omputing the siz e func tions . When the siz e func tions or sc oped sizing is used , the mesh distr ibution is influenc ed b y •The minimum and maximum siz e values •The gr owth r ate •The siz e sour ce which c an b e an y one of the f ollowing: –Edge and fac e cur vature, based on the nor mal angle v ariation b etween adjac ent edges or fac es. –Edge and fac e pr oximit y, based on the numb er of elemen t layers cr eated in a gap b etween edges or fac es. –The b ody of influenc e defined . –Constan t user-defined siz es thr ough har d and sof t behaviors .The cur vature, proximit y, body of influenc e, and sof t siz e func tions ha ve sof t behavior.The meshed and har d siz e func tions ha ve har d behavior. This chapt er contains the f ollowing sec tions: 8.1.Types of S ize Functions or Sc oped S izing C ontrols 8.2. Defining S ize Functions 8.3. Defining Sc oped S izing C ontrols 8.4. Computing the S ize Field 207Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.8.5. Using the S ize Field 8.1. Types of S ize Func tions or Sc oped S izing C ontrols The f ollowing siz e func tions or sc oped sizing c ontrols ar e available: 8.1.1. Curvature 8.1.2. Proximit y 8.1.3. Meshed 8.1.4. Har d 8.1.5. Soft 8.1.6. Body of Influenc e 8.1.1. Curvature The cur vature siz e func tion/sc oped c ontrol comput es edge and fac e siz es using their siz e and nor mal angle par amet ers, which ar e either aut oma tically c omput ed or defined . The cur vature sizing is defined b y the f ollowing par amet ers: •Min, Max siz e •Growth r ate •Normal angle The cur vature siz e func tion/sc oped c ontrol uses the nor mal angle par amet er as the maximum allo wable angle tha t one elemen t edge ma y span. For e xample a v alue of 5 implies tha t a division will b e made when the angle change along the cur ve is 5 degr ees; henc e, a 90 degr ee ar c will b e divided in to ap- proxima tely 18 segmen ts. Note As the cur vature values ar e comput ed appr oxima tely using edges and fac e fac ets, ther e may be some numer ical er rors, esp ecially when fac e fac ets ar e excessiv ely str etched . Figur e 8.1: Use of C urvature Sizing (p.209) sho ws an e xample wher e the sur face has b een r emeshed based on a cur vature siz e func tion. The change in nor mal angle and gr owth r ate controls the siz e distr ibution. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 208Size Functions and Sc oped S izingFigur e 8.1: Use of C urvature Sizing 8.1.2. Proximit y The pr oximit y siz e func tion/sc oped c ontrol comput es edge and fac e siz es in ‘gaps ’ using the sp ecified minimum numb er of elemen t layers. For the pur poses of sp ecifying pr oximit y sizing , a ‘gap’ is defined in one of t wo ways: •The ar ea b etween t wo opp osing b oundar y edges of a fac e •The in ternal v olumetr ic region b etween t wo fac es The pr oximit y sizing is defined b y the f ollowing par amet ers: •Min, Max siz e •Growth r ate •Cells p er gap Figur e 8.2: Use of P roximit y Sizing (p.210) sho ws an e xample wher e the sur face has b een r emeshed based on a pr oximit y siz e func tion. The change in the c ells p er gap and gr owth r ate par amet ers c ontrol the siz e distr ibution. 209Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Types of S ize Functions or Sc oped S izing C ontrolsFigur e 8.2: Use of P roximit y Sizing Note For pr oximit y siz e func tions , the numb er of c ells p er gap c an b e a r eal v alue , with a minimum of 0.1. This has the eff ect of incr easing the siz e of fac e elemen ts lo cated far ther a way from edges , and str etching fac e elemen ts with lar ger siz es along side fac es, or gaps , ther eby re- ducing the o verall fac e coun t, and ultima tely the c ell c oun t. Additional options f or defining the fac e pr oximit y sizing ar e as f ollows: •The Face Boundar y option enables y ou t o comput e the shell pr oximit y (edge-edge pr oximit y within each face).The pr oximit y between f eature edges on the fac e zones selec ted is c omput ed.This option is par ticular ly useful f or resolving tr ailing edges and thin pla tes without using the har d siz e func tion. The e xample in Figur e 8.3: Use of the F ace Boundar y Option f or F ace Proximit y (p.211) sho ws the use of this option f or a blade c onfigur ation. Though the nor mals on the blade sur face point out ward, the c ells acr oss the tr ailing edges will b e refined based on the pr oximit y siz e func tion defined f or the tr ailing sur faces when the Face Boundar y option is enabled . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 210Size Functions and Sc oped S izingFigur e 8.3: Use of the F ace Boundar y Option f or F ace Proximit y Note The Face Boundar y option w orks on the in ternally e xtracted b oundar y edge z ones of the fac e zones . Edge z ones e xtracted in the meshing mo de/C AD imp orted edges will not be consider ed f or the pr oximit y calcula tion. •The Face - F ace option enables y ou t o comput e the pr oximit y between t wo fac es in the fac e zones selec ted. When the Face - F ace option is enabled , additional options f or ignor ing self pr oximit y (Ignor e Self) and ignor ing the fac e nor mal or ientation ( Ignor e Or ientation ) are also a vailable . The Ignor e Self option c an b e used with the Face - F ace option in c ases wher e self pr oximit y (proximit y between fac es in the same fac e zone) is t o be ignor ed.This option is disabled b y default. The Ignor e Or ientation option c an b e used t o ignor e the fac e nor mal or ientation dur ing the pr ox- imit y calcula tion. This option is enabled b y default. In gener al, the pr oximit y dep ends on the dir ection of fac e nor mals . An example is sho wn in Figur e 8.4: Use of the Ignor e Or ientation Option f or F ace Proximit y (p.212).The nor mals on the gr ooved b ox point inw ard.With only the Face - F ace option, the pr oximit y siz e func tion do es not r efine the sur face along the en tire gr oove length. When the Ignor e Or ientation option is enabled along with the Face - F ace option, the sur face will b e refined along the gr oove length. 211Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Types of S ize Functions or Sc oped S izing C ontrolsFigur e 8.4: Use of the Ignor e Or ientation Option f or F ace Proximit y Note You must selec t at least one of the Face Boundar y and Face - F ace options; other wise , an error will b e reported. The edge pr oximit y siz e func tion dep ends only on the distanc e between the edges , irrespective of their asso ciation with a fac e zone or the or ientation of the fac e zones asso ciated with the edge z ones . Imp ortant When using a pr oximit y sizing in c ertain geometr ies (with angle > 30 degr ees or c ompr ising extended r egion of non-in tersec ting fac es), the pr oximal fac e zones ma y not b e det ected and ma y result in a w arning message . In such c ases , split the pr oximit y sizing in to multiple proximit y sc oped sizing c ontrols. Tip When using a pr oximit y siz e func tion with geometr ies ha ving a v ery lar ge numb er of small feature edges , you c an sp eed up the c alcula tion and r educ e memor y requir emen ts b y en- abling Quick E dge P roximit y. Go to Displa y → Controls, selec t Size Func tions from the Categor ies drop do wn list , and check Quick E dge P roximit y. Accur acy will b e reduc ed when Quick E dge P roximit y is enabled . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 212Size Functions and Sc oped S izing8.1.3. Meshed The meshed siz e func tion/sc oped c ontrol enables y ou t o set the siz e based on e xisting siz es.This provides gr adation b etween the minimum and maximum siz e based on the sp ecified gr owth r ate. The default b ehavior f or the meshed siz e func tion/sc oped c ontrol is sof t, allo wing other har d siz es or locally smaller siz es to override it. You c an enable Hard M eshed S ize Func tions by going t o the Displa y > Controls menu , and selec ting Size Func tions in the dr op do wn list. Note In R elease 15.0 and ear lier, the b ehavior f or the meshed siz e func tion/sc oped c ontrol w as hard.This b ehavior is sa ved with the mesh file .Therefore, when r eading a mesh sa ved using such a r elease , the Hard M eshed S ize Func tions control ma y be enabled . The meshed sizing is defined b y the gr owth r ate. In Figur e 8.5: Use of M eshed S izing (p.213), the fac e zone is r emeshed based on the pr emeshed fac e zone indic ated. Figur e 8.5: Use of M eshed S izing 8.1.4. Hard The har d siz e func tion/sc oped c ontrol enables y ou t o main tain a unif orm siz e based on the siz e sp ecified , while the gr owth r ate from the defined siz e influenc es the siz e on adjac ent zones .The har d sizing will override an y other siz e func tion sp ecified . The har d sizing is defined b y the f ollowing par amet ers: •Min Size •Growth r ate Imp ortant •It is r ecommended t o not ha ve two har d siz es ne xt to each other as the mesh siz e transition between the t wo will not b e smo oth. 213Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Types of S ize Functions or Sc oped S izing C ontrols•If two har d siz es ar e applied a t the same lo cation, the la tter will b e honor ed.The smaller siz e rule do es not apply in this c ase. 8.1.5. Soft The sof t siz e func tion/sc oped c ontrol enables y ou t o set the maximum siz e on the selec ted z one , while the sp ecified gr owth r ate from the defined siz e influenc es the siz e on adjac ent zones .When the soft sizing is selec ted f or edges and/or fac es, the siz e will b e aff ected b y other siz e func tions/sc oped c ontrols. The minimum siz e on the z one will b e det ermined based on the influenc e of other siz e func tions/sc oped controls, else a unif orm siz e will b e main tained . In other w ords, a sof t sizing is ignor ed in a r egion wher e other sizing c ontrols sp ecify smaller siz es. The sof t sizing is defined b y the f ollowing par amet ers: •Max siz e •Growth r ate In the e xample in Figur e 8.6: Use of S oft Sizing (p.214), the minimum siz e is det ermined b y the har d sizing applied on the smaller fac e zones indic ated, and maximum siz e is limit ed b y the sof t sizing ap- plied . Figur e 8.6: Use of S oft Sizing 8.1.6. Body of Influenc e The b ody of influenc e siz e func tion/sc oped c ontrol enables y ou t o sp ecify a b ody of influenc e (tha t is, a region f or sizing c ontrol).The maximum mesh siz e will b e equal t o the sp ecified siz e within the Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 214Size Functions and Sc oped S izingbody of influenc e.The minimum siz e will b e det ermined based on the influenc e of other siz e func- tions/sc oped c ontrols. An example is sho wn in Figur e 8.7: Use of B ody of Influenc e Sizing (p.215). Note The set of fac e zones selec ted t o define the b ody of influenc e should c onstitut e a geomet- rically closed r egion. If an op en r egion is used as a b ody of influenc e, the sizing will b e processed as a sof t sizing . The b ody of influenc e sizing is defined b y the f ollowing par amet ers: •Max S ize •Growth r ate In Figur e 8.7: Use of B ody of Influenc e Sizing (p.215), the mesh is gener ated based on the b ody of in- fluenc e sizing defined .The finer mesh siz e is obtained due t o other siz e func tions (f or e xample , curvature, proximit y) defined in addition t o the b ody of influenc e siz e func tions . Figur e 8.7: Use of B ody of Influenc e Sizing Imp ortant •In case of multiple non-in tersec ting closed b odies , a single BOI siz e func tion/sc oped sizing control can b e set up .The sizing c an b e sc oped t o the set of fac e zones c ompr ising the r espective bodies . •In case of multiple in tersec ting closed b odies f or sc oping the same BOI sizing , you need t o create separ ate BOI siz e func tions/sc oped sizing c ontrols f or each geometr ic body. Note When using BOI s with p eriodic b oundar ies, if the BOI e xtends outside the domain, it ma y cause unnec essar y refinemen t. 8.2. Defining S ize Func tions Size func tions c an b e defined using the Size Func tions dialo g box. Right-click on Model in the tr ee and selec t Func tions ... from the Sizing menu .The gener ic pr ocedur e to define siz e func tions is as f ollows: 215Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Defining S ize Functions1. Ensur e tha t the global c ontrols ar e set as r equir ed.The r elevant siz e func tion par amet er values (minimum and maximum siz e, growth r ate) will b e up dated based on the global c ontrols sp ecified . 2. Enable Face Zones (or Edge Z ones ) as appr opriate. 3. Selec t the b oundar y zones (or the edge z ones) f or which the siz e func tion is t o be defined in the Boundar y Zones (or Edge Z ones ) selec tion list. Note All boundar y fac e zones and edge z ones included in the global domain ar e available for defining siz e func tions , even if a lo cal domain has b een ac tivated. 4. Selec t the appr opriate siz e func tion t ype in the Size Func tion Type drop-do wn list in the Define S ize Func tion group b ox. 5. Enter an appr opriate siz e func tion name in the Name field or lea ve the field blank if y ou w ant to ha ve the name gener ated aut oma tically. In this c ase, the Name will b e assigned acc ording t o the z one t ype (face or edge) and the siz e func tion t ype. (For e xample ,face-cur vature-sf-5 indic ates tha t the cur vature size func tion is defined f or fac e zones .The siz e func tion ID is 5.) 6. Specify the siz e func tion par amet ers applic able f or the selec ted siz e func tion as appr opriate and click Create. The defined siz e func tion will b e available in the Size Func tions list. 8.2.1. Creating D efault S ize Func tions You c an cr eate default siz e func tions based on fac e and edge cur vature and pr oximit y using the Create Defaults option in the Size Func tions dialo g box. Alternatively, you c an use the c ommand /size- functions/create-defaults to cr eate the default siz e func tions . The f ollowing siz e func tions will b e defined: •Curvature siz e func tion on all edge z ones , with the global minimum and maximum siz es and gr owth r ate, and a nor mal angle of 18. •Curvature siz e func tion on all fac e zones , with the global minimum and maximum siz es and gr owth r ate, and a nor mal angle of 18. •Proximit y siz e func tion on all edge z ones , with the global minimum and maximum siz es and gr owth r ate, and the c ells p er gap set t o 3. •Proximit y siz e func tion on all fac e zones , with the global minimum and maximum siz es and gr owth r ate, and the c ells p er gap set t o 3. When the Create D efaults option is used af ter the default siz e func tions ha ve been cr eated, the pr e- vious definitions will b e up dated based on an y changes t o the global minimum and maximum siz es and gr owth r ate. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 216Size Functions and Sc oped S izing8.3. Defining Sc oped S izing C ontrols Scoped sizing c ontrols c an b e defined using the Scoped S izing dialo g box. Right-click on Model in the tree and selec t Scoped... from the Sizing menu .The gener ic pr ocedur e for defining sc oped sizing controls is as f ollows: 1. Set the global sc oped sizing c ontrols as r equir ed.The r elevant local control par amet er values (minimum and maximum siz e, growth r ate) will b e up dated based on the global v alues sp ecified . 2. Selec t the appr opriate sc oped c ontrol type in the Type drop-do wn list in the Local Sc oped S izing group box. 3. Enter an appr opriate name in the Name field . 4. Specify the lo cal sizing par amet ers applic able f or the selec ted sc oped c ontrol type as appr opriate. 5. Selec t the sc ope for the sc oped c ontrol defined fr om the Scope To drop-do wn list. Additionally , selec t the Objec t Type (Geom and/or Mesh) and sp ecify a suitable pa ttern in the Selec tions field . You c an also click to op en the Scope dialo g box and selec t the objec ts, face zone lab els, face zones , or edge z ones f or defining the siz e control sc ope. 6. Click Create New. The defined siz e control will b e available in the Controls list. You c an v alida te the defined sc oped sizing c ontrols using the c ommand /scoped-sizing/validate . An er ror will b e reported if the sc oped sizing c ontrols do not e xist or the sc ope for one (or mor e) controls is in valid. 8.3.1. Size Control F iles The siz e controls file (*.szcontrol ) contains the sc oped sizing c ontrol definitions .The c ontrol name and t ype, and the sc ope of the c ontrol will b e included in the siz e control file along with global siz e paramet ers. To read a siz e controls file , click Read ... in the Scoped S izing dialo g box to in voke the Selec t File dialo g box and sp ecify the name of the file t o be read. Alternatively, you c an use the /scoped- sizing/read command and sp ecify the name of the file t o be read. To wr ite a siz e controls file , click Write... in the Scoped S izing dialo g box to in voke the Selec t File dialo g box and sp ecify the name of the file t o be wr itten. Alternatively, you c an use the /scoped- sizing/write command and sp ecify the name of the file t o be wr itten. 8.4. Computing the S ize Field The siz e field c an b e comput ed based on the defined siz e func tions and sc oped sizing c ontrols b y click ing Comput e in the Size Func tions dialo g box or the Scoped S izing dialo g box. Alternatively, use 217Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Computing the S ize Fieldthe c ommand /size-functions/compute or /scoped-sizing/compute to comput e the siz e field . Imp ortant If the siz e field has b een c omput ed in the cur rent session, sizes will b e based on the c omput ed size field .You c annot define additional siz e func tions or sc oped sizing c ontrols, or mo dify the cur rent siz es without deleting the siz e field . 8.4.1. Size Field F iles Size field files c ontain the siz e func tion definitions based on the par amet ers sp ecified . Selec t the File/Read/S ize Field ... menu t o read a siz e field file .This will in voke the Selec t File dialo g box, wher e you c an sp ecify the name of the siz e field file t o be read. Alternatively, you c an use the /file/read-size-field command and sp ecify the name of the file t o be read. Imp ortant If a siz e field file has b een r ead in the cur rent session, sizes will b e based on the siz e field read.You c annot define additional siz e func tions or sc oped sizing c ontrols, or mo dify the current siz es without deleting the siz e field . Selec t the File/W rite/Size Field ... menu t o sa ve a siz e field file based on the par amet ers set. This will invoke the Selec t File dialo g box, wher e you c an sp ecify the name of the siz e field file t o be wr itten. Alternatively, you c an use the /file/write-size-field command and sp ecify the name of the file t o be wr itten. 8.4.2. Using S ize Field F ilters Additional siz e field filt ering options ar e available af ter the siz e field is c omput ed/r ead.These options are available in the Size Field F ilters dialo g box. Click Filters... in the Size Func tions or Scoped S izing dialo g box to op en the Size Field F ilters dialo g box. •You c an sp ecify a sc ale fac tor to filt er the siz e output fr om the siz e field , without deleting and r ecomputing the siz e field .The sc aling filt er can b e applied as f ollows: 1. Specify an appr opriate value f or Factor,Min and Max (for Scale). 2. Click Apply . Alternatively, you c an use the c ommand /size-functions/set-scaling-filter , and sp ecify the sc ale fac tor, minimum and maximum siz e values . •You c an apply p eriodicit y to the siz e field , without deleting and r ecomputing the siz e field as f ollows: 1. Click Set... to op en the Periodicit y dialo g box. 2. Selec t the t ype of p eriodicit y (Rota tional or Transla tional ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 218Size Functions and Sc oped S izing3. For tr ansla tional p eriodicit y, specify the shif t vector comp onen ts You c an also click Define and selec t 2 no des t o set up the shif t vector for tr ansla tional p eriodicit y. 4. For rotational p eriodicit y, enter an appr opriate value f or Angle . 5. For rotational p eriodicit y, specify the piv ot p oint and axis of r otational p eriodicit y. You c an also selec t 1–6 no des and click Define to set up the piv ot p oint and axis of r otation for rotational p eriodicit y as f ollows: –If only 1 no de is selec ted, the piv ot p oint is a t the no de lo cation and the axis of r otation is the global z-axis . –For 2 no des, the piv ot p oint is a t the midp oint of the no des selec ted and the axis of r otation is the global z-axis . –For 3 no des, the piv ot p oint is a t the first no de selec ted.The axis of r otation is the lo cal z-axis nor mal to the plane defined b y the thr ee p oints, the p ositiv e dir ection is det ermined b y the r ight-hand r ule. –For 4, 5 or 6 no des, the first 3 p oints define a cir cle.The piv ot p oint is a t the c enter of the cir cle.The axis of r otation is the lo cal z-axis nor mal t o the cir cular plane , the p ositiv e dir ection is det ermined by the r ight-hand r ule. 6. Click Apply to enable Periodicit y in the Size Field F ilters dialo g box. Note –If periodicit y is set up pr ior t o computing the siz e-field , the Periodicit y filter will b e en- abled when the siz e-field is c omput ed. Alternatively, you c an set up the p eriodic b oundar y using the Make Periodic B oundar ies dialo g box. See Creating P eriodic B oundar ies (p.320) for details . Boundar y → Create → Periodic... You c an also use the c ommand /size-functions/enable-periodicity-filter and sp ecify the angle , pivot, and axis of r otation. If periodicit y has b een pr eviously defined , the e xisting settings will b e applied . 8.4.3. Visualizing S izes Before computing the siz e field , you c an check if the global minimum and maximum siz es ar e suitable locally. After computing the siz e field , you c an set the selec tion filt er to size and use the pr obe to determine lo cal siz e or mak e a c ontour plot of the sizing on an y sur face You c an displa y the c ontours of siz e using the options in the Size Func tions dialo g box as f ollows: 1. Selec t the fac e zones in the Boundar y Zones selec tion list in the Size Func tions dialo g box. 2. Specify appr opriate values f or Min and Max in the Contours group b ox. 3. Click Draw (in the Contours group b ox). 219Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Computing the S ize FieldAlternatively, after selec ting the fac e zones , use the hot k ey Ctrl+T (Miscellaneous Tools), then Ctrl+C to dr aw siz e contours . Figur e 8.8: Contours of S ize (p.220) sho ws the displa y of c ontours of siz e on the selec ted fac e zones after the siz e field has b een c omput ed or r ead Figur e 8.8: Contours of S ize A visual indic ation of mesh siz e is also a vailable using the mouse pr obe. Size selec tion filt er If the selec tion filt er is set t o size (hot k ey Ctrl+Y), right-click a t the r equir ed lo cations t o see the siz e boxes indic ating the mesh siz e. See Figur e 8.9: Displa y of M esh S ize Based on S ize Field (p.220). Figur e 8.9: Displa y of M esh S ize Based on S ize Field Preview siz es Alternatively, after selec ting the fac e zones , use the hot k ey Ctrl+T (Miscellaneous Tools), then Ctrl+P to preview siz es on the selec ted z ones .You c an set the minimum and maximum siz e values in the Preview Sizes dialo g box. 8.5. Using the S ize Field The siz e field c an b e used t o remesh sur faces and edges .The C utCell mesher also uses the siz e field t o refine the initial C artesian mesh. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 220Size Functions and Sc oped S izingRemeshing S urfaces The gener ic pr ocedur e for remeshing sur faces is as f ollows: 1. Selec t the sur face(s) t o be remeshed .You c an use the gr aphics selec t tools or selec t from a list in a dialo g box. 2. Use the hotk ey Ctrl+Shift+R or click the R emesh butt on t o op en the Zone Remesh dialo g box. 3. Choose the appr opriate Sizing from the dr op do wn list and set other par amet ers as nec essar y. 4. Click Remesh . For mor e control of sur face remeshing par amet ers, use the Surface Retr iangula tion dialo g box as f ollows: Boundar y → Mesh → Remesh 1. Selec t the sur faces to be remeshed in the Face Zones list. 2. Enable Size Func tion in the Face Remesh Options group b ox and click the Specify butt on t o op en the Size Func tions dialo g box and check tha t the siz e func tions ar e appr opriate. See Defining S ize Func- tions (p.215). Alternatively, ensur e tha t the siz e field has b een c omput ed or r ead in. 3. Set the other options f or fac e remeshing as appr opriate. 4. Click Remesh . Imp ortant Edge z ones asso ciated with fac e zones ar e not r emeshed implicitly . If you ha ve feature edge z ones asso ciated with the sur face being r emeshed , you need t o remesh them b efore remeshing the fac e zones . Remeshing E dges The gener ic pr ocedur e for remeshing edges is similar t o the ab ove pr ocedur e for sur faces. Use the hotk ey Ctrl+Shift+Z, or click the E dge Z one r estriction butt on, to constr ain the selec tion t o edge z ones only . For mor e control of edge r emeshing par amet ers, use the Feature M odify dialo g box as f ollows: Boundar y → Mesh → Feature 1. Ensur e tha t the edge z ones ar e extracted as r equir ed. 2. Selec t the edges t o be remeshed in the Edge Z ones list in the Feature M odify dialo g box. 3. Selec t Remesh in the Options list and selec t Size Func tion in the Metho d drop-do wn list. 4. Make sur e the siz e func tions ar e defined as appr opriate in the Size Func tions dialo g box (see Defining Size Functions (p.215)). Alternatively, ensur e tha t the siz e field has b een c omput ed or r ead in. 221Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the S ize Field5. Click Apply . Refining the C utC ell M esh The C utCell mesher uses the siz e func tions/siz e field t o refine the initial C artesian mesh as descr ibed in The C utCell M eshing P rocess (p.433). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 222Size Functions and Sc oped S izingChapt er 9: Objec ts and M aterial P oints This chapt er descr ibes the use of objec ts and ma terial p oints for iden tifying the mesh r egion. 9.1. Objec ts 9.2. Material P oints 9.1. Objec ts An objec t—gener ally a set of fac e zones and edge z ones—is used t o iden tify the domain t o be meshed . By including edge z ones in the objec t definition, you ar e able t o captur e the objec t features e ven when wrapping . Objec ts ar e gener ally closed solid v olumes , closed fluid (w etted) v olumes , capping sur faces, or individual face zones tha t can b e used f or meshing . For e xample , using c apping sur faces in c onjunc tion with a material p oint and a closed solid v olume enables y ou t o extract the flo w volume using wr apping . Objec ts (defined or imp orted) ar e indep enden t of each other ; tha t is, objec ts do not shar e fac e and/or edge z ones . In c ases wher e objec ts ar e defined using a c ommon fac e/edge z one , the c ommon fac e/edge zones ar e duplic ated t o mak e the objec ts indep enden t. Objec t Based M eshing Objec ts can b e used f or mesh gener ation as descr ibed: Surface M eshing Objec t wr apping or join and in tersec t op erations ar e used t o create a c onformal, connec ted sur face mesh. This is the first of a t wo-st ep pr ocess f or cr eating a t etrahedr al, hexcore, polyhedr al, or h ybrid mesh in meshing objec ts.This pr ocess is descr ibed in Objec t-Based Sur face Meshing (p.239). Volume M eshing The Volumetr ic Regions are calcula ted fr om the c onformal, connec ted sur face mesh, and then filled with tetrahedr al, hexcore, or p olyhedr al mesh, with or without infla tion la yers.This is the sec ond of a t wo-st ep process f or meshing objec ts and is descr ibed in Objec t-Based Volume M eshing (p.263) Auto M esh An objec t-based w orkflow to gener ate a v olume mesh. You c an selec t the desir ed mesh objec t in the Model tr ee and selec t Auto M esh... from the menu a vailable . Alternatively, use the Mesh → AutoMesh... menu t o op en the Auto M esh dialo g box, then selec t the mesh objec t in the Objec t drop-do wn list. See Using the A uto M esh D ialog Box (p.349) or Meshing A ll Regions C ollec tively U sing A uto Mesh (p.268) for details on using the Auto M esh dialo g box. Note The No Fill option is not a vailable when a mesh objec t is selec ted f or v olume meshing . 223Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Auto Fill Volume A selec tive workflow to gener ate a v olume mesh on selec ted v olumetr ic regions .You c an selec t the desir ed Volumetr ic Regions in the M odel tr ee and selec t Auto Fill Volume from the menu a vailable . See Meshing R egions S elec tively U sing A uto Fill Volume (p.271). CutC ell M eshing A gener al pur pose, hex-dominan t meshing t echnique using a dir ect sur face and v olume appr oach. Objec ts can b e used t o det ermine the inclusion of C artesian gr id en tities f or C utCell meshing .The C artesian gr id will b e refined and snapp ed t o an y fac e zone included in the objec ts selec ted f or C utCell meshing . See Gener ating the C utCell M esh (p.433). Objec ts descr iptions include attribut es (type, cell z one t ype and pr iority) and entities (fac e zone lab els, volumetr ic regions and c ell z ones). You c an manage y our objec ts using se veral tools acc essible with hotk eys, onscr een t ool butt ons, text commands , or b y using t ools in the Manage O bjec ts dialo g box.Tools e xist f or op erations such as objec t creation, mo dific ation, changing pr opertes, alignmen t, remeshing , deleting , mer ging , and mo ving . 9.1.1. Objec t Attribut es 9.1.2. Objec t Entities 9.1.3. Managing O bjec ts 9.1.1. Objec t Attribut es Each objec t has a ttribut es such as objec t type, cell z one t ype, and pr iority. Objec t Type The following objec t types ar e available: Geometr y Objec ts imp orted thr ough C AD using the C AD F aceting option (see Imp orting C AD F iles (p.112)) or created f or a giv en geometr y.The geometr y objec ts ma y be non-c onformal. Mesh Objec ts tha t are go od qualit y sur face mesh r epresen tations of the geometr y. Mesh objec ts ma y contain multiple v olumes with shar ed fac es.They ma y be imp orted using the CFD S urface M esh option f or CAD imp ort or cr eated using the objec t wr apping options . Mesh objec ts can also b e created using the S ew op eration. Cell Z one Type The objec t cell z one t ype indic ates the t ype of c ell z one cr eated when the mesh is gener ated based on objec ts. Figur e 9.1: Mesh With D ifferent Cell Z one Types (p.225) sho ws a C utCell mesh with diff erent cell zone t ype assigned t o respective objec ts. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 224Objec ts and M aterial P ointsFigur e 9.1: Mesh With D ifferent Cell Z one Types Priority The objec t priority controls the inclusion of the mesh en tities . In c ase of o verlapping objec ts, the en tities in the o verlapp ed r egion will b e included with the objec t ha ving a higher pr iority value . Figur e 9.2: Use of the O bjec t Priority for O verlapping O bjec ts (p.225) sho ws an e xample with o ver- lapping objec ts.The o verlapp ed r egion is included with the z one c orresponding t o the objec t having the higher pr iority value (in this c ase, 4). Figur e 9.2: Use of the O bjec t Priority for O verlapping O bjec ts Note Multiple objec ts ha ving the same pr iority assigned will b e mer ged in to a single c ell zone , irrespective of c ell z one t ype. Priority is also imp ortant when objec ts ar e created f or b ounding b oxes or wind tunnels , and so on. In such c ases , the objec t created f or a b ounding b ox or wind tunnel must b e assigned the lowest pr iority. 225Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Objec ts9.1.1.1. Creating O bjec ts Figur e 9.3: Creating O bjec ts—Example (p.226) sho ws the Subtr act metho d for cr eating objec ts, using an e xample with thr ee non-in tersec ting b odies . Figur e 9.3: Creating O bjec ts—E xample The or der of pr iority assigned t o individual objec ts is imp ortant when using the Subtr act metho d. Zones in higher pr iority objec ts will b e ignor ed when defining lo wer pr iority objec ts. In this c ase the order of pr iority is objec t-1 > objec t-2 > objec t-3. Figur e 9.4: Objec ts D efined U sing the S ubtr act Metho d 1. Selec t the fac e and edge z ones c ompr ising the inner most b ody, set the Cell Z one type, and set the highest Priority value . 2. Selec t the fac e and edge z ones c ompr ising the inner b ody, set the Cell Z one type, and set an in terme- diate Priority value . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 226Objec ts and M aterial P oints3. Selec t the fac e and edge z ones c ompr ising the out er b ody, set the Cell Z one type, and set the lo west Priority value . Note Objec ts (defined or imp orted) ar e indep enden t of each other ; tha t is, objec ts do not shar e face and/or edge z ones . In c ases wher e objec ts ar e defined using a c ommon fac e/edge zone , the c ommon fac e/edge z ones ar e duplic ated t o mak e the objec ts indep enden t. 9.1.2. Objec t Entities Objec t en tities include fac e zone lab els, volumetr ic regions , and c ell z ones .Volumetr ic regions and cell z ones ar e available only f or mesh objec ts. •Face zone lab els: For geometr y objec ts, these ar e gr oups of fac e zones c ompr ising the objec t. For mesh objec ts, these ar e or iginal C AD z ones or b odies , or fac e zones c ompr ising the mesh objec t. If the mesh objec t is cr eated b y mer ging multiple mesh objec ts, the fac e zone lab els r epresen t the objec ts tha t were mer ged .They pr ovide the link t o the or iginal geometr y. When the CAD A ssemblies option is selec ted f or C AD imp ort, you c an set up lab els f or the C AD zones , if requir ed. Named S elec tions ar e also imp orted as lab els.These lab els ar e pr eser ved throughout the objec t-based meshing w orkflow in F luen t Meshing . Several tools f or managing F ace Zone Lab els ar e available via the c ontext-sensitiv e menus . Note Geometr y objec ts can c ontain unlab eled z ones . Mesh objec ts alw ays contain fac e zone labels which ar e der ived fr om the asso ciated geometr y objec ts. In c ase of unlab eled z ones in the geometr y objec t, the mesh objec t fac e zone lab el is the same as the asso ciated geometr y objec t. •Volumetr ic regions: These ar e finit e, contiguous domains tha t are ready for v olume meshing . •Cell z ones: These ar e created when the v olume mesh is gener ated. 9.1.2.1. Using F ace Zone L abels Various options ar e available f or fac e zone lab els via the c ontext-sensitiv e menus in the tr ee: •The c ontext-sensitiv e menu f or Face Zone L abels contains options f or dr awing and selec ting all lab els and obtaining an o verall summar y or detailed inf ormation ab out the fac e zone lab els. For Geometr y O bjec ts, you ha ve these additional options: –Unlab eled fac e zones c an b e lab eled using the Create Labels... option. The Create Labels dialo g box op ens. Selec t the fac e zones fr om the Face Zones selec tion list and sp ecify an appr opriate Label N ame . For geometr y objec ts, you c an cho ose t o list all a vailable objec t fac e zones or only unlab eled objec t fac e zones f or selec tion. Enable the 227Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Objec tsCreate a lab el for each fac e zone check box to gener ate an individual lab el for each fac e zone . –Use the Remo ve All Labels fr om Z ones ... to remo ve lab eled fac e zones fr om an objec t. The Remo ve All Labels dialo g box op ens. Selec t the O bjec t and Lab eled F ace Zones , and then click Remo ve All. Note Unlab eled fac e zones ar e not supp orted f or M esh objec ts. –Unlab eled z ones c an b e dr awn and/or selec ted without ha ving t o cr eate a new lab el using the Unlab eled Z ones ... options . For Mesh O bjec ts, you ha ve the additional Join/In tersec t... option which op ens a dialo g box to assist with cr eating a c onformal sur face mesh. •The c ontext-sensitiv e menu f or individual lab els contains options f or renaming , mer ging , and deleting face zone lab els in addition t o the standar d options f or dr awing and selec ting all lab els, and obtaining an overall summar y or detailed inf ormation. You c an also add or r emo ve zones fr om an e xisting fac e zone lab el. –Selec t Add Z ones ... from the c ontext sensitiv e menu t o op en the Add Z ones t o Label dialo g box. Selec t the fac e zones and click Add. For geometr y objec ts, you c an add unlab eled z ones or those alr eady included in other lab els within the objec t selec ted. –Selec t Remo ve Zones ... from the c ontext sensitiv e menu t o op en the Remo ve Zones fr om L abel dialo g box. Selec t the fac e zones and click Remo ve. For Mesh O bjec ts, the c ontext-sensitiv e menu f or individual lab els c ontains additional options f or: –connec ting the fac e zones using Join/In tersec t.... –finding and r epair ing fac e connec tivit y and qualit y pr oblems using Diagnostics .... –creating or r ecovering p eriodic b oundar ies using Rec over P eriodic.... 9.1.3. Managing O bjec ts You c an manage y our objec ts using se veral tools acc essible with hotk eys, onscr een t ool butt ons, text commands , or b y using t ools in the Manage O bjec ts dialo g box. Tools e xist f or op erations such as objec t creation, mo dific ation, changing pr opertes, alignmen t, remeshing , deleting , mer ging , and mo ving . 9.1.3.1. Using hotk eys and onscr een t ools 9.1.3.2. Using the M anage O bjec ts D ialog Box Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 228Objec ts and M aterial P oints9.1.3.1. Using hotk eys and onscr een t ools Tools f or the most c ommon objec t managemen t op erations ar e acc essible via hotk eys, icons, or t ext commands . 9.1.3.1.1. Creating O bjec ts for C AD En tities 9.1.3.1.2. Creating O bjec ts for U nreferenced Z ones 9.1.3.1.3. Creating M ultiple O bjec ts 9.1.3.1.4. Easy O bjec t Creation and M odific ation 9.1.3.1.5. Changing O bjec t Properties 9.1.3.1.6. Automa tic A lignmen t of O bjec ts 9.1.3.1.7. Remeshing G eometr y Objec ts 9.1.3.1.8. Creating E dge Z ones 9.1.3.1.1. Creating O bjec ts for C AD E ntities When the CAD A ssemblies option is selec ted f or C AD imp ort, the C AD en tities c an b e used t o cr eate or mo dify geometr y/mesh objec ts.The objec ts ar e asso ciated with the C AD en tities (which ar e then locked), enabling r e-imp orting or up dating of selec ted par ts or b odies using diff erent fac eting qualities and t opology represen tations f or quick design changes and up dates. •Use the options in the Objec t menu f or C AD en tities f or cr eating geometr y/mesh objec ts and mo difying existing objec ts. Selec t the C AD en tities in the tr ee and then cho ose the appr opriate menu option. Al- ternatively, selec t the C AD objec ts in the gr aphics displa y and selec t the option fr om the CAD Tools. See Creating and M odifying G eometr y/M esh O bjec ts (p.203) for details . •Use the options in the CAD A ssociation menu f or geometr y/mesh objec ts for mo difying the selec ted objec ts based on the asso ciated C AD en tities .You c an also a ttach or detach the C AD en tities fr om the objec ts. See CAD A ssociation (p.205) for details . 9.1.3.1.2. Creating O bjec ts for Unr efer enc ed Z ones Use the options in the Create O bjec ts dialo g box to define objec ts for unr eferenced b oundar y fac e zones and edge z ones . Right click Boundar y Face Zones in the Unreferenc ed branch of the tr ee and selec t Create New O bjec ts... from the c ontext-sensitiv e menu . 1.Enter an appr opriate name in the Objec t Name field . You c an also ha ve the objec t name gener ated aut oma tically b y lea ving the Objec t Name field blank. In this c ase, the objec t name will b e assigned based on the Prefix , cell z one t ype, and priority sp ecified (f or e xample , an objec t named objec t-fluid:3-20 has pr efix objec t-, cell z one type fluid , priority 3, and objec t ID 20). 2.Selec t the appr opriate option fr om the Cell Z one Type drop-do wn list. 3.Set the pr iority. 4.Selec t the appr opriate type from the Objec t Type drop-do wn list (default ,geom ). 5.Enable the Create a lab el for each fac e zone check box to gener ate an individual lab el for each face zone . 6.Click Create. 229Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Objec ts9.1.3.1.3. Creating Multiple O bjec ts You c an also cr eate one objec t per selec ted z one using the c ommand /objects/create-mul- tiple .This is par ticular ly useful f or C AD e xported mo dels , as y ou c an define an objec t per par t. An objec t will b e created f or each selec ted z one and will b e named aut oma tically based on the specified pr efix and pr iority.The name assigned is prefix fac e zone name-pr iority:objec t ID . (For example , an objec t named objec t-wall-3:20 will b e created f or the fac e zone wall, with the sp ecified prefix objec t- and pr iority 3.The objec t ID is 20.) 1.Specify the first and last z one f or which objec ts ar e to be created.You c an also use wild-c ards for sp e- cifying the fac e zones t o be consider ed. Note You need t o sp ecify v alid z one names or IDs . 2.Specify the pr efix t o be used f or the objec t name and the c ell z one t ype. 3.Specify the pr iority for the first objec t (for the first z one selec ted) and the incr emen t in pr iority. When the incr emen t is set t o a v alue gr eater than z ero, the pr iority will b e assigned in the or der of fac e zone ID . If the incr emen t is set t o zero, all objec ts will ha ve the same pr iority. A geometr y objec t will b e created f or the first and last z one (as sp ecified) and f or all v alid fac e zones having IDs b etween the first and last z one . 9.1.3.1.4. Easy O bjec t Creation and Mo dific ation You c an easily mo ve a z one fr om one objec t to another or cr eate a new objec t using the Transf er Zones tool ( ) or Ctrl+Shift+Y hotk ey combina tion. 1.Selec t the z one(s) t o be mo ved or t o form a new objec t. 2.Press the hotk ey combina tion or click . 3.If a tar get objec t is set , the selec ted z one(s) ar e mo ved t o the tar get. If no tar get is set , enter the new objec t name in the Create Geometr y Objec t dialo g box. To set a tar get objec t, 1.Selec t the objec t using the mouse pr obe. 2.Press the hotk ey combina tion Ctrl+S or . Note Empt y objec ts will b e aut oma tically delet ed. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 230Objec ts and M aterial P oints9.1.3.1.5. Changing O bjec t Properties Use the Change O bjec t Properties dialo g box to change the pr operties of objec ts based on selec tions in the gr aphics windo w. Selec t one or mor e objec ts and then use the hot-k ey Ctrl+Shift+N to op en the Change O bjec t Properties dialo g box. Alternatively, selec t the objec ts in the M odel tr ee and then selec t Rename/C hange P roperties ... from the menu a vailable t o acc ess the Change O bjec t Properties dialo g box. If a single objec t is selec ted, you c an sp ecify a new objec t name . If multiple objec ts ar e selec ted, you c an sp ecify a c ommon pr efix f or the objec ts selec ted.This enables y ou t o easily view the objec ts with the same pr efix using the tr ee view butt on f or selec tion lists .You c an also cho ose t o rename objec t zones and set the geometr y recovery option f or the objec t zones (high or lo w). 9.1.3.1.6. Automatic A lignment of O bjec ts You ma y also fit objec ts together in pr ecise alignmen t, for e xample t o position a flange on a b ody by aligning b olt holes . The pr ocedur e is initia ted via the hotk ey Ctrl+Shift+G, and uses a t emp orary local coordina te sy stems (LCS) t o achie ve the alignmen t. Defining a lo cal coordina te sy stem b y selec ting 1-6 no des w orks as f ollows: •If only 1 no de is selec ted, the L CS or igin is a t the no de lo cation and ax es ar e aligned t o global c o- ordina te sy stem. •For 2 no des, the L CS or igin is a t the midp oint of no des and ax es ar e aligned t o global c oordina te system. •For 3 no des, the or igin is a t the first p oint, the L CS x-axis is along a v ector fr om the first t o the sec ond point, and the L CS y-axis is along a v ector fr om the first p oint to the 3r d point. •For 4, 5 or 6 no des, the first 3 p oints define a cir cle.The L CS or igin is a t the c enter of the cir cle and the z-axis is nor mal t o the cir cular plane (p ositiv e dir ection is det ermined b y the r ight-hand r ule). –For 4 no des, the x-axis is defined b y a v ector fr om the c enter of the cir cle t o the pr ojec tion of the 4th p oint on the cir cular plane . –For 5 no des, the x-axis is defined b y a v ector fr om the c enter of the cir cle t o the pr ojec tion of the mid-p oint of 4th and 5th p oints on the cir cular plane . –For 6 no des, the x-axis is defined b y a v ector fr om the c enter of the cir cle t o the pr ojec tion of the circumc enter of 4th, 5th and 6th p oints on the cir cular plane . 9.1.3.1.7. Remeshing G eometr y O bjec ts You c an cr eate mesh objec ts fr om the geometr y objec ts without wr apping b y using the Remesh dialo g box. 1.Selec t Remesh... in the c ontext-sensitiv e menu f or geometr y objec ts to op en the Remesh dialo g box. 2.Selec t Individually or Collec tively from the Target list. Enter the objec t name when using the c ollec tive option. 231Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Objec ts3.Click OK. The siz e field based on cur rently defined sizing c ontrols or siz e func tions will b e used t o remesh the geometr y objec ts. 9.1.3.1.8. Creating E dge Z ones You c an cr eate edge z ones on selec ted fac e zones or selec ted sur faces using the onscr een t ools or context menus .This f eature is descr ibed in Extract Edge Z ones (p.327). 9.1.3.2. Using the M anage O bjec ts D ialo g Box The Manage O bjec ts dialo g box contains options tha t enable y ou t o define objec ts and p erform certain objec t manipula tion op erations . Right-click on Model in the tr ee and selec t Objec t Managemen t... from the menu t o acc ess the Manage O bjec ts dialo g box. •Selec t the Objec ts,Face Zones , or Edge Z ones from their r espective lists as r equir ed. Note If edge z ones ar e to be included in the objec t definition, the y must ha ve been cr e- ated and visible in the lists . •List all z ones controls ho w fac e and edge z ones ar e list ed. –If enabled , all a vailable z ones ar e list ed. –If disabled , the lists will c ontain only z ones tha t are not included in e xisting objec ts.You c an use this t o iden tify z ones tha t are not asso ciated with objec ts. •Selec t Objec t Zones controls highligh ting of fac e and edge z ones in the lists . If enabled , when an objec t is selec ted, face and edge z ones in the objec t will b e highligh ted. Choose one of the tabs t o acc ess the objec t managemen t tools. 9.1.3.2.1. Defining O bjec ts 9.1.3.2.2. Objec t Manipula tion Op erations 9.1.3.2.3. Objec t Transf ormation Op erations 9.1.3.2.1. Defining O bjec ts You c an define the objec ts using the options in the Definition tab of the Manage O bjec ts dialo g box. 1. Enter an appr opriate name in the Objec t Name field . You c an also ha ve the objec t name gener ated aut oma tically b y lea ving the Objec t Name field blank. In this c ase, the objec t name will b e assigned based on the Prefix , cell z one t ype, and priority sp ecified (f or e xample , an objec t named objec t-fluid:3-20 has pr efix objec t-, cell z one type fluid , priority 3, and objec t ID 20). 2. Selec t the appr opriate option fr om the Cell Z one Type drop-do wn list. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 232Objec ts and M aterial P oints3. Set the pr iority. 4. Selec t the appr opriate type from the Objec t Type drop-do wn list (default ,geom ). 5. Click Create. You c an mo dify the objec t definition using the Change option in the Manage O bjec ts dialo g box. Selec t the objec t to be mo dified , mak e the nec essar y changes in the Definition tab , and click Change . You c an also use the Change Type to M esh option in the menu a vailable f or geometr y objec ts. Objec ts can b e delet ed using the Delet e option in the Definition tab .You c an also enable Include Faces and E dges to delet e the fac es and edges c ompr ising the objec t, when the objec t is delet ed. Note When an objec t is delet ed along with the fac e and edge z ones c ompr ising the objec t, any corresponding fac e/edge gr oups will also b e delet ed. 9.1.3.2.2. Objec t Manipulation O perations The f ollowing objec t manipula tion op erations c an b e performed using the options in the Operations tab of the Manage O bjec ts dialo g box or using the options fr om the menu a vailable on an y geometr y or mesh objec t selec ted in the Outline View: •Objec ts of the same t ype (geometr y or mesh) c an b e mer ged using the Merge O bjec ts... option. Specify the name f or the mer ged objec t in the Merge O bjec ts dialo g box. When multiple mesh objec ts ar e mer ged , the fac e zone lab els r epresen t the objec ts tha t were mer ged . Imp ortant Merging z ones tha t ha ve diff erent fac e zone lab els will r esult in a mer ged z one with the or iginal lab els app ended . •Wall fac e zones c ompr ising objec ts can b e mer ged using the Merge Walls option. •The edge z ones c ompr ising an objec t can b e mer ged in to a single edge z one using the Merge E dges option. Note If the objec t contains edge z ones of diff erent types (b oundar y and in terior), the edge zones of the same t ype (b oundar y or in terior) will b e mer ged in to a single edge z one . •Intersec tion lo ops c an b e created within an objec t or b etween objec ts using the options in the Intersec tion Loops group b ox. 233Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Objec ts•Edge z ones c an b e extracted fr om the fac e zones included in the sp ecified objec ts, based on the f eature angle v alue sp ecified using the options in the Edge Z ones group b ox.You c an sp ecify whether only feature edges or all edges ar e to be extracted f or the objec ts selec ted. Previously cr eated edges will automa tically b e disasso ciated fr om the objec t and added t o the Unreferenc ed branch of the Outline View tr ee. Note –This func tionalit y is also a vailable in the Extract Edges dialo g box. See Extract Edge Zones (p.327) –Similar func tionalit y is also a vailable in the F eature Modify dialo g box and Sur face Retrian- gular ization dialo g box. See Creating and M odifying F eatures (p.291) and Remeshing Boundar y Zones (p.298). •A fac e gr oup and an edge gr oup c ompr ising the fac e zones and edge z ones included in the sp ecified objec ts can b e created using the options in the Zone G roup group b ox. •The fac e zones c ompr ising the objec t can b e separ ated based on the angle or seed sp ecified using the options in the Separ ate Faces group b ox. •When the fac e zones and/or edge z ones c ompr ising an objec t are delet ed, you will b e pr ompt ed t o up date the objec t definition. You c an use the c ommand /objects/update to up date the defined objec ts per the changes . •You c an r ename the fac e and edge z ones c ompr ising the objec t based on the objec t name and also specify the separ ator to be used . 9.1.3.2.3. Objec t Transformation O perations The f ollowing objec t transf ormation op erations c an b e performed using the options a vailable in the Transf ormations tab of the Manage O bjec ts dialo g box: •Objec ts can b e rotated using the Rota te option. Specify the angle of r otation and the piv ot p oint and the axis of r otation b y selec ting 1-6 no des in the gr aphics windo w. The piv ot p oint and the axis of r otation c an b e defined b y selec ting 1-6 no des as f ollows: –If only 1 no de is selec ted, the piv ot p oint is a t the no de lo cation and the axis of r otation is the global z-axis . –For 2 no des, the piv ot p oint is a t the midp oint of the no des selec ted and the axis of r otation is the global z-axis . –For 3 no des, the piv ot p oint is a t the first no de selec ted.The axis of r otation is the lo cal z-axis normal t o the plane defined b y the thr ee p oints, the p ositiv e dir ection is det ermined b y the right-hand r ule. –For 4, 5 or 6 no des, the first 3 p oints define a cir cle.The piv ot p oint is a t the c enter of the cir cle. The axis of r otation is the lo cal z-axis nor mal t o the cir cular plane , the p ositiv e dir ection is de- termined b y the r ight-hand r ule. •Objec ts can b e sc aled using the Scale option. Specify the sc ale fac tors (X, Y, Z) f or the sc aling op eration. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 234Objec ts and M aterial P oints•Objec ts can b e transla ted using the Transla te option. Specify the v ector comp onen ts to define the transla tion, or click Define and selec t two scr een lo cations t o det ermine the tr ansla tion. 9.2. Material P oints In addition t o objec ts, ma terial p oints can b e defined t o allo w the mesher t o separ ate the c ell z one . Typic ally, a ma terial p oint can b e defined t o retrieve a c ell z one f or which an objec t cannot b e defined , or the objec t definition alone is not sufficien t to retrieve the c ell z one . Material p oints can also b e used to retrieve regions fr om a non-c ontiguous c ell z one . Contiguous r egions will b e separ ated based on the r espective ma terial p oints defined .The c ell z one r etrieved based on the defined ma terial p oint will be of the t ype fluid and ha ve the sp ecified name . The f ollowing e xamples demonstr ate the use of a ma terial p oint in addition t o objec ts: •Some c ases in volving “dirty” geometr y ma y result in multiple v oids . In this c ase, the v olume t o be meshed can b e recovered b y defining an objec t compr ising the z ones enclosing the domain t o be meshed , combined with a ma terial p oint within the e xpected meshed domain (see Figur e 9.5: Using M aterial P oints—Ex- ample (p.235)). Figur e 9.5: Using M aterial P oints—E xample Note The in tersec tion lo ops c an b e created (see Objec t Manipula tion Op erations (p.233)) to re- cover the in tersec ting f eatures accur ately. •In Figur e 9.6: Example—C utCell M esh, Only O bjec ts D efined (p.236), the use of only objec ts to define the meshed domain r esults in a mesh with t wo cell z ones ,solid and fluid . 235Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Material P ointsFigur e 9.6: Example—C utC ell M esh, Only O bjec ts D efined By sp ecifying a ma terial p oint in addition t o the objec t definition (fluid or dead), the fluid zone in Figur e 9.6: Example—C utCell M esh, Only O bjec ts D efined (p.236) will b e fur ther separ ated in to a fluid zone (c ontaining the ma terial p oint) and a dead z one (see Figur e (A) (p.236)). If auto-delete- dead-zones? is enabled (default), the separ ated dead z ones will b e delet ed aut oma tically ( Figur e (B) (p.236)). (A) C utCell M esh—M aterial P oint and O bjec ts D efined ,auto-delete-dead-zones? Disabled (B) C utCell M esh—M aterial P oint and O bjec ts D efined ,auto-delete-dead-zones? Enabled Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 236Objec ts and M aterial P ointsNote For c ases wher e a single r egion is separ ated b y a double-sided sur face (fan,radia tor, or porous-jump ), you need t o define a ma terial p oint for each of the r egions t o be recovered (tha t is, both upstr eam and do wnstr eam of the double-sided sur face). Separ ate cell z ones will b e recovered f or each r egion on either side of the double-sided sur face. You c an mer ge the c ell z ones manually af ter the mesh has b een gener ated. •Figur e 9.7: Example—F luid Sur face Ex tracted F rom G eometr y Objec ts and M aterial P oint (p.237) sho ws the use of a ma terial p oint in addition t o objec ts defined t o extract the in ternal fluid sur face, using the objec t wrapping op eration. Figur e 9.7: Example—F luid S urface Extracted F rom G eometr y O bjec ts and M aterial P oint 9.2.1. Creating M aterial P oints Right-click Model in the tr ee and selec t Material P oints... from the menu t o acc ess the Material Points dialo g box. Click Create... to op en the Create M aterial P oint dialo g box. Follow the pr ocess descr ibed. 237Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Material P oints1. Selec t the appr opriate zones or objec ts in the gr aphics windo w.The selec tions should b e such tha t the material p oint created will lie a t a c entral point in the fluid domain. 2. Click Comput e to obtain the ma terial p oint coordina tes based on the selec tions . You c an also sp ecify the c oordina tes manually if the ma terial p oint location is k nown. 3. Enable Preview to verify tha t the lo cation is appr opriate. 4. Enter an appr opriate fluid z one name in the Name field . 5. Click Create. Use the List butt on t o displa y the x-, y-, and z- c oordina tes of the selec ted ma terial p oint(s) in the console . Use the Delet e butt on t o remo ve the selec ted ma terial p oint(s). Use the Draw butt on t o displa y the selec ted ma terial p oint(s) in the gr aphics windo w. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 238Objec ts and M aterial P ointsChapt er 10: Objec t-Based S urface M eshing Objec t-based meshing is the r ecommended meshing appr oach with which y ou c an gener ate a t etrahedr al, hexcore, or p olyhedr al volume mesh, with or without infla tion la yers. In this appr oach, you first cr eate a conformal, connec ted sur face mesh on all the objec ts to be meshed .The sur face mesh, and ma terial points if r equir ed, are then used t o iden tify the r egions t o be filled with the v olume mesh. This chapt er descr ibes the pr ocesses used t o cr eate a c onformal, connec ted sur face mesh. Steps t o create the v olume mesh ar e descr ibed in Objec t-Based Volume M eshing (p.263). Refer to Objec ts and Material P oints (p.223) for mor e inf ormation on meshing objec ts. Imp ortant Ensur e tha t the mo del is suitably sc aled dur ing imp ort and the global minimum siz e is a t least 0.01 t o avoid numer ical pr oblems dur ing mesh gener ation. The t ools t o complet e the objec t-based sur face meshing st eps ar e found in the c ontext-sensitiv e menus in the Outline View or in the onscr een t ools and hotk eys. Instr uctions ar e descr ibed in the f ollowing sections . 10.1. Sur face Mesh P rocesses 10.2. Prepar ing the G eometr y 10.3. Diagnostic Tools 10.4. Connec ting O bjec ts 10.5. Advanced Options 10.1. Surface M esh P rocesses In pr incipal, ther e ar e two basic w orkflows to cr eate a c onformal, connec ted sur face mesh fr om an un- connec ted assembly . Note It is assumed tha t objec ts ar e alr eady created up on C AD imp ort. Objec t managemen t, if nec essar y, is descr ibed in Objec ts (p.223). Single fluid v olume using Wrapp er based w orkflo w The basic Wrapp er based w orkflow for a single fluid v olume simula tion f ollows these st eps: 1.Imp ort the C AD mo del using the CAD F aceting tessella tion option. Geometr y objec ts ar e created. See Imp orting C AD F iles (p.112) for additional inf ormation. 2.Define sizing and c omput e the siz e field . 239Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Scoped S izing is r ecommended t o apply individual siz e controls on sp ecific objec ts as r equir ed. See Defining Sc oped S izing C ontrols (p.217) for additional inf ormation. 3.Define ma terial p oints to assist in iden tifying the fluid v olume . See Material P oints (p.235) for additional inf ormation. 4.Check and fix the geometr y, par ticular ly gaps . You c an use the c ontext menu Diagnostics → Geometr y, acc essible fr om an y Geometr y objec t, to assist in finding an y geometr y issues . See Diagnostic Tools (p.247) for additional inf ormation. Missing geometr y objec ts ma y be constr ucted as descr ibed in Prepar ing the G eometr y (p.241). 5.Define p eriodic b oundar ies, if applic able . See Creating P eriodic B oundar ies (p.320) for additional inf ormation. 6.Wrap the mo del. Step thr ough the options a vailable in the Wrap context menu . See The Wrapping P rocess (p.325) for details . 7.Check the mesh and impr ove the qualit y, if nec essar y. You c an use the c ontext menu Diagnostics → Connec tivit y and Q ualit y, acc essible fr om an y mesh objec t. Comple x topology using J oin and In tersec t based w orkflo w The basic J oin/in tersec t based w orkflow for c omple x topology such as CHT simula tion, follow these steps: 1.Imp ort the C AD mo del using the CFD S urface M esh tessela tion option. Mesh objec ts ar e created. See Imp orting C AD F iles (p.112) for additional inf ormation. Note If the assembly has alr eady been c onnec ted (f or e xample , using S hare Topology operations in ANSY S DesignM odeler or S paceClaim), it is sufficien t to just imp ort the CAD using the One objec t per file and CFD S urface M esh options . 2.Check the mesh and fix the c onnec tivit y, if nec essar y. You c an use the c ontext menu Diagnostics → Connec tivit y and Q ualit y, acc essible fr om an y mesh objec t. 3.Check and fix the geometr y, par ticular ly gaps . You c an use the c ontext menu Diagnostics → Geometr y, acc essible fr om an y Geometr y objec t, to assist in finding an y geometr y issues . See Diagnostic Tools (p.247) for additional inf ormation. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 240Objec t-Based Sur face MeshingMissing geometr y objec ts ma y be constr ucted as descr ibed in Prepar ing the G eometr y (p.241). 4.Merge all objec ts to a single objec t using the Merge option in the c ontext menu . 5.Connec t all b odies . You c an use the Join/In tersec t context menu or the onscr een t ools f or Join or Intersec t. See Connec ting O bjec ts (p.251) for additional inf ormation. 6.Optionally define sizing , comput e the siz e field and r emesh if nec essar y. Remesh is r ecommended as it of ten r educ es mesh c oun t and impr oves qualit y while main taining sufficien t mesh densit y.You c an use the Remesh F aces context menu or the onscr een t ools. Computing a siz e field is nec essar y only if y ou cho ose t o remesh. Scoped S izing is r ecommended to apply individual siz e controls on sp ecific objec ts as r equir ed. See Defining Sc oped S izing Controls (p.217) for additional inf ormation. 7.Define p eriodic b oundar ies, if applic able . See Creating P eriodic B oundar ies (p.320) for additional inf ormation. 8.Check the mesh and impr ove the qualit y, if nec essar y. You c an use the c ontext menu Diagnostics → Connec tivit y and Q ualit y, acc essible fr om an y mesh objec t. When the sur face mesh is c onformally c onnec ted and of sufficien t qualit y, proceed t o gener ate the volume mesh as descr ibed in Objec t-Based Volume M eshing (p.263). 10.2. Prepar ing the G eometr y When the geometr y is imp orted fr om C AD, ther e ma y be a numb er of gaps and the fac eted geometr y may be disc onnec ted.Though op erations such as mer ging no des and fac eted stit ching c an b e used t o partially c onnec t the mo del, some gaps ma y remain and f eatures ma y be lost. You ma y want to perform tasks such as cr eate a wind tunnel or far-field domain, close annular gaps , create capping sur faces for inlets or outlets , or cr eate gr oups of z ones f or mo dels with a lar ge numb er of zones . Right-click on Model in the tr ee and selec t the appr opriate option fr om the menu t o acc ess the options t o perform such op erations . 10.2.1. Using a B ounding B ox 10.2.2. Closing A nnular G aps in the G eometr y 10.2.3. Patching Tools 10.2.4. Using U ser-D efined G roups 10.2.1. Using a B ounding B ox The b ounding b ox tool can b e used t o cr eate a wind tunnel or far-field domain f or the imp orted geometr y. A geometr y objec t can b e created f or the b ounding b ox sur face created.You c an also use the b ounding b ox tool to cr eate a b ody of influenc e to be used f or defining siz e func tions . See Using the B ounding B ox Dialog Box (p.310) for details on the options f or cr eating a b ounding b ox. Right-click on Model in the tr ee and selec t Constr uction G eometr y → Bounding B ox... to op en the Bounding Box dialo g box. 241Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Prepar ing the G eometr y10.2.2. Closing A nnular G aps in the G eometr y See Creating a C ylinder/F rustum (p.313) to cr eate a c ylindr ical or annular sur face to close r adial gaps in the geometr y. A geometr y objec t can b e created f or the sur face created. Right-click on Model in the tr ee and selec t Constr uction G eometr y → Cylinder ... to op en the Cylinder dialo g box. Figur e 10.1: Closing a R adial G ap (p.242) sho ws an e xample wher e a r adial gap is closed using a c yl- indr ical sur face. Figur e 10.1: Closing a R adial G ap 1. Selec t 3 Arc, 1 H eigh t Node in the Options list. 2. Click Selec t Nodes ... and selec t 3 no des on one cir cle and one (heigh t no de) on the other acr oss the radial gap . 3. Enter an appr opriate value f or Edge L ength . 4. Enable Create Objec t and disable Caps. 5. Click Create. 10.2.3. Patching Tools The pa tching t ools enable filling of unw anted holes in the geometr y. A hole ma y be bounded b y either free edges or f eature edges . Use the pa tching t ools t o: •patch holes asso ciated with fr ee fac es in multiple z ones •fill punched holes in a single z one •cap inlets/outlets and assign the appr opriate zone t ype •patch other c omple x shap es to close gaps including shar p angles and small p ockets in the geometr y using the lo op selec tion t ools Use the pa tching t ools t o lo cate and fix the major holes in the geometr y. If you miss an y holes , you can fix them la ter using the hole det ection f eature. See Fixing H oles in O bjec ts (p.331) for details . 10.2.3.1. Using the P atch Options D ialog Box 10.2.3.2. Using the L oop S elec tion Tool Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 242Objec t-Based Sur face Meshing10.2.3.1. Using the P atch O ptions D ialo g Box When the pa tching t ools ar e used , by default , the new fac es ar e added t o a new fac e zone and ar e remeshed .These options ar e available in the Patch Options group in the r ibbon. •Remesh enables the aut oma tic r emeshing of the pa tched ar ea. •Separ ate enables the cr eation of a separ ate fac e zone/objec t for the new fac es cr eated. Additional options for objec t/zone gr anular ity and t ype are available in the Patch Options dialo g box. The Patch Options dialo g box contains options f or objec t/zone gr anular ity and t ype and is a vailable when the Separ ate option is selec ted. Specify the objec t/zone gr anular ity as f ollows: •Selec t New O bjec t to create a new objec t for the fac e zones . Specify the objec t name and a lab el name . If the lab el name is not sp ecified , the objec t name will b e used as the lab el name . Face zone names will be the same as the lab el names . Selec t the Objec t Type and Zone Type from the lists . •Selec t Add t o O bjec t to add the fac e zones t o an e xisting objec t. Selec t the objec t and sp ecify a lab el name . If the lab el name is not sp ecified , the default name patch:# (# indic ates the ID) will b e used . Face zone names will b e the same as the lab el names . Selec t the Zone Type from the list. •Selec t Add t o Unreferenc ed to create unr eferenced fac e zones . Selec t the Zone Type from the list. The default name patch:# (# indic ates the ID) will b e used f or the z one name .These z ones will b e available in the Unreferenc ed branch of the tr ee. Using E dge/N ode S elec tions Selec t edges/no des in the gr aphics windo w to fix the holes in the geometr y. •Fixing holes b y selec ting edges . 1. Set the pa tching options in the Patch Options group in the r ibbon. 2. Selec t the edge filt er ( or hot-k ey Ctrl+E) and selec t an y edge on the hole b oundar y.You c an selec t either fr ee edges or f eature edges . 3. Click or pr ess F5 to create the sur face tha t closes the hole . a. If the Separ ate option is enabled , set the objec t/zone gr anular ity and t ype in the Patch Options dialo g box (Using the P atch Options D ialog Box (p.243)). If the Remesh option is enabled , the face zones will b e remeshed . b.Click Create in the Patch Options dialo g box. Figur e 10.2: Creating a Sur face Using an E dge (p.244) sho ws an e xample wher e the c apping sur face is cr eated b y selec ting an edge on the e xisting objec t. 243Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Prepar ing the G eometr yFigur e 10.2: Creating a S urface Using an E dge •Fixing holes b y selec ting no des. 1. Set the pa tching options in the Patch Options group in the r ibbon. 2. Selec t the no de filt er ( or hot-k ey Ctrl+N) and selec t the no des ar ound the hole . 3. Press or F5 to create the sur face tha t closes the hole . a. If the Separ ate option is enabled , set the objec t/zone gr anular ity and t ype in the Patch Options dialo g box (Using the P atch Options D ialog Box (p.243)). If the Remesh option is enabled , the face zones will b e remeshed . b.Click Create in the Patch Options dialo g box. Figur e 10.3: Creating a Sur face Using N odes (p.245) sho ws an e xample wher e the c apping sur faces are created b y selec ting no des on the e xisting objec t. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 244Objec t-Based Sur face MeshingFigur e 10.3: Creating a S urface Using N odes Patching Multiple H oles in a S ingle Z one All holes asso ciated with fr ee edges or punched holes in a single z one c an b e closed in a single patching op eration using the hot-k ey Ctrl+R ( ). 1. Set the pa tching options in the Patch Options group in the r ibbon. 2. Selec t the appr opriate en tity for the op eration: •For pa tching holes with fr ee fac es, selec t the appr opriate fac e zones in the gr aphics windo w. •For pa tching punched holes , selec t a fac e adjac ent to a hole in the fac e zone . Note Punched holes c an b e closed only in a single fac e zone ha ving finit e thick ness . There should b e no fr ee fac es in the fac e zone b eing pa tched . 245Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Prepar ing the G eometr y3. Click or use the hot-k ey Ctrl+R. a. If the Separ ate option is enabled , set the objec t/zone gr anular ity and t ype in the Patch Options dialo g box (Using the P atch Options D ialog Box (p.243)). If the Remesh option is enabled , the fac e zones will b e remeshed . b.Click Create in the Patch Options dialo g box. 10.2.3.2. Using the L oop S elec tion Tool The lo op selec tion t ool can b e acc essed b y click ing in the gr aphics windo w or using the hot- key Ctrl+Shift+L.This t ool pr ovides additional options , such as using f ewer no de selec tions , for cr e- ating the c apping sur face.You c an also selec t positions t o define the lo op. The f ollowing selec tion options ar e available: •In the first gr oup of t ools, cho ose ho w the pa th b etween selec ted no des/p ositions is defined - b y edges , feature, boundar y, or dir ect pa th. Click to swit ch b etween selec ting no des or p ositions t o define the loop. •The sec ond gr oup of ic ons is used t o selec t op en or closed lo op.Then, for closed lo op mo de, you c an choose ho w the pa th b etween the first and last no des is defined - b y edges , feature, boundar y, or dir ect path. After mak ing the nec essar y selec tions , click or use the hot-k ey Ctrl+K in the L oop S elec tion mode t o op en the Create Cap dialo g box. The Create Cap dialo g box contains options f or objec t/zone gr anular ity and t ype and f or remeshing the c apping sur face. 1. Specify the objec t/zone gr anular ity. •Selec t New O bjec t to create a new objec t for the fac e zones . Specify the objec t name and a lab el name . If the lab el name is not sp ecified , the objec t name will b e used as the lab el name . Face zone names will b e the same as the lab el names . Selec t the Objec t Type and Zone Type from the lists . •Selec t Add t o O bjec t to add the fac e zones t o an e xisting objec t. Selec t the objec t and sp ecify a lab el name . If the lab el name is not sp ecified , the default name patch:# (# indic ates the ID) will b e used . Face zone names will b e the same as the lab el names . Selec t the Zone Type from the list. •Selec t Add t o Unreferenc ed to create unr eferenced fac e zones . Selec t the Zone Type from the list. The default name patch:# (# indic ates the ID) will b e used f or the z one name .These z ones will b e available in the Unreferenc ed branch of the tr ee. 2. Enable Remesh to remesh the c apping sur face created. 3. Click Create in the Create Cap dialo g box. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 246Objec t-Based Sur face MeshingFor the list of hot-k eys asso ciated with the options in the L oop S elec tion t oolbar , refer to Ap- pendix C: Shortcut Ke ys (p.527). 10.2.4. Using U ser-D efined G roups You c an define user-defined gr oups t o better handle lar ge mo dels .The options f or manipula ting user- defined gr oups ar e available in the User D efined G roups dialo g box. Right-click on Model in the tr ee and selec t Groups ... to op en the User D efined G roups dialo g box. You c an cr eate a fac e gr oup and an edge gr oup c ompr ising the fac e zones and edge z ones included in the sp ecified objec ts using the options in the Zone G roup group b ox in the Operations tab in the Manage O bjec ts dialo g box.You c an ac tivate a par ticular gr oup using the Activate option in the User Defined G roups dialo g box. Additionally , a fac e zone gr oup is aut oma tically cr eated when a mesh objec t is cr eated using the Sew operation. This fac e zone gr oup is pr efixed b y _mesh_gr oup , and enables easy selec tion of mesh objec t face zones f or v arious op erations (impr ove, smo oth, and so on). Note When an objec t is delet ed along with the fac e and edge z ones c ompr ising the objec t, the corresponding gr oups will also b e delet ed. Imp ortant You c annot cr eate a new gr oup ha ving the name global , or ha ving the same name as one of the default gr oups . 10.3. Diagnostic Tools The options in the Diagnostic Tools dialo g box enable y ou t o find and fix pr oblems in b oundar y meshes , or displa y boundar y mesh sta tistics , of selec ted objec ts.The Diagnostic Tools dialo g box is acc essed by selec ting the appr opriate option fr om the Diagnostics sub-menu a vailable b y right-click ing on an y geometr y or mesh objec t selec ted in the Outline View. Diagnostic t ools ar e available f or the f ollowing: •finding and fixing Geometr y problems , such as gaps or in tersec tions b etween objec ts. •finding and fixing Connec tivit y problems in the sur face mesh, such as fr ee or multi-c onnec ted edges , and o verlapping or in tersec ting fac es. •finding and fixing Qualit y problems in the sur face mesh. A Summar y table of mesh sta tistics c an b e obtained using the Summar y butt on a t the b ottom of the Diagnostic Tools dialo g box, or fr om the c ontext-sensitiv e menu on an y geometr y or mesh objec t se- lected in the tr ee. 10.3.1. Geometr y Issues 10.3.2. Face Connec tivit y Issues 10.3.3. Qualit y Check ing 247Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Diagnostic Tools10.3.4. Summar y Note When selec ting Diagnostics ... from under a mesh objec t’s Face Zone L abel, the Geometr y options ar e not a vailable .The dialo g box contains only Face Connec tivit y and Qualit y options for the b oundar y zones included in the Face Zone L abel. 10.3.1. Geometr y Issues Problems in the geometr y, such as gaps or in tersec tions c an b e lo cated and fix ed using the diagnostic tools. Selec t the objec ts (geometr y or mesh) in the M odel tr ee, and then selec t Geometr y... from the Diagnostics sub-menu a vailable fr om the c ontext-sensitiv e menu . 1. Selec t the desir ed Issue and then set the r elevant mar king options .The issues tha t can b e diagnosed are as f ollows: •Self In tersec tions •Cross In tersec tions •Self F ace Proximit y •Cross F ace Proximit y •Self E dge P roximit y 2. Click Mark to iden tify and obtain a c oun t of the Unvisit ed problems in y our b oundar y mesh. 3. Click First (Next) to step thr ough the pr oblems individually . At each st ep, the iden tified pr oblem r egion will b e highligh ted in the gr aphics windo w. 4. To correct the iden tified pr oblem (if nec essar y), click the appr opriate butt on in the Operations group box.You c an cho ose t o fix all iden tified pr oblem ar eas or the ar ea tha t is cur rently displa yed. Note Many other geometr y mo dific ation t ools ar e available .The butt ons pr esen ted in the Oper- ations group b ox represen t the most lik ely t ools f or the t ype of issue . 10.3.2. Face Connec tivit y Issues Problems in the sur face mesh such as fr ee or multi-c onnec ted fac es, self-in tersec ting fac es, or other problema tic c onfigur ations c an b e lo cated and fix ed using the diagnostic t ools. Selec t the objec ts Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 248Objec t-Based Sur face Meshing(geometr y or mesh) in the M odel tr ee, and then selec t Connec tivit y and Q ualit y... from the Diagnostics sub-menu a vailable fr om the c ontext-sensitiv e menu . Note If a Face Zone L abel is selec ted under a mesh objec t, the Diagnostics ... menu will not have an y submenu choic es, but will op en dir ectly with Face Connec tivit y and Qualit y options a vailable . 1. Selec t the b oundar y zones t o be examined . •Selec t All to selec t the b oundar y zones fr om a list including all b oundar y fac e zones a vailable . •Selec t Unmeshed to selec t the b oundar y zones fr om a list of the unmeshed tr i zones a vailable .The unmeshed z ones ar e those tha t are not c onnec ted t o a v olume mesh. 2. On the Face Connec tivit y tab , selec t the desir ed Issue and then set the r elevant mar king options .The issues tha t can b e diagnosed ar e as f ollows: •Free •Multi •Self In tersec tions •Self P roximit y •Duplic ate •Spikes •Islands •Steps •Slivers •Point Contacts •Invalid N ormals Note Zone-sp ecific or sc oped pr ism settings should b e applied pr ior t o using this option. •Leaks •Deviation 3. Click Mark to iden tify and obtain a c oun t of the Unvisit ed problems in y our b oundar y mesh. 249Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Diagnostic Tools4. Click First (Next) to step thr ough the pr oblems individually . At each st ep, the iden tified pr oblem r egion will b e highligh ted in the gr aphics windo w. 5. To correct the iden tified pr oblem (if nec essar y), click the appr opriate butt on in the Operations group box.You c an cho ose t o fix all iden tified pr oblem ar eas or the ar ea tha t is cur rently displa yed. Note Many other mesh mo dific ation t ools ar e available . For e xample , you c an do Local Remesh (use the hotk ey Ctrl+Shift+R) or S mooth ( F6) inst ead of C ollapse ( Ctrl+J) to remo ve sliv ers. The butt ons pr esen ted in the Operations group b ox represen t the most lik ely t ools f or the type of issue . 10.3.3. Qualit y Check ing Problems with the sur face mesh qualit y can b e lo cated and fix ed using the diagnostic t ools. Selec t the objec ts (geometr y or mesh) in the M odel tr ee, and then selec t Connec tivit y and Q ualit y... from the Diagnostics sub-menu a vailable fr om the c ontext-sensitiv e menu . Note If a Face Zone L abel is selec ted under a mesh objec t, the Diagnostics ... menu will not have an y submenu choic es, but will op en dir ectly with Face Connec tivit y and Qualit y tabs available . 1. Selec t the b oundar y zones t o be examined . •Selec t All to selec t the b oundar y zones fr om a list including all b oundar y fac e zones a vailable . •Selec t Unmeshed to selec t the b oundar y zones fr om a list of the unmeshed tr i zones a vailable .The unmeshed z ones ar e those tha t are not c onnec ted t o a v olume mesh. 2. On the Qualit y tab , set the numb er of qualit y measur es and sp ecify up t o thr ee qualit y measur es to be used .Then selec t from the f ollowing qualit y measur e options . •Skewness •Size Change •Edge R atio •Area •Aspect Ratio •Warp •Dihedr al Angle •Ortho S kew Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 250Objec t-Based Sur face Meshing3. Click Mark to iden tify and obtain a c oun t of the Unvisit ed problems in y our b oundar y mesh. 4. Click First (Next) to step thr ough the pr oblems individually . At each st ep, the iden tified pr oblem r egion will b e highligh ted in the gr aphics windo w. 5. To correct the iden tified pr oblem (if nec essar y), selec t the appr opriate option in the Operations group box and click Apply f or A ll. Alternatively, you c an cho ose t o collapse or smo oth all mar ked fac es tha t are cur rently displa yed. For mor e inf ormation on ho w Fluen t calcula tes the qualit y and adjusts the mesh, see the Qualit y Measur es (p.492) page . Note Many other mesh mo dific ation t ools ar e available . For e xample , you c an do Local Remesh (use the hotk ey Ctrl+Shift+R) inst ead of S mooth ( F6) or C ollapse ( Ctrl+J) to remo ve a skewed fac e.The butt ons pr esen ted in the Operations group b ox represen t the most lik ely tools f or the t ype of issue . 10.3.4. Summar y A tabular summar y of mesh sta tistics c an b e displa yed in the c onsole b y selec ting Summar y from the context sensitiv e menu f or a geometr y or mesh objec t in the Outline View tr ee. The displa yed da ta includes the numb er of fr ee-, multi-, and duplic ate fac es; face qualit y (sk ewness) statistics , and t otal numb er of fac es and fac e zones .This is the same inf ormation as is displa yed b y click ing the Summar y butt on in the Diagnostic Tools dialo g box. 10.4. Connec ting O bjec ts The join and in tersec t op erations ar e used t o connec t fac e zone lab els within a mesh objec t by joining overlapping fac es or in tersec ting fac e zones . In c ase of multiple mesh objec ts, mer ge the objec ts in to a single mesh objec t and then pr oceed t o join/in tersec t them. For b est r esults , it is r ecommended tha t faces b e of similar siz e wher e the join or in tersec t op eration is o ccur ring.The pr ocess is in teractive, fast , scriptable , and enables dir ect control o ver lo cal shap e and qualit y, and v olumetr ic and sur face overlaps . Join/In tersec t ma y be emplo yed as a b ottom-up str ategy tha t enables y ou t o build multiple sub-assem- blies individually , and then c onnec t the sub-assemblies t o cr eate the final assembly . It can b e used t o connec t all the fac e zone lab els within a mesh objec t into the final assembly in one op eration. Supp ort for par t replac emen t without global r emeshing is inher ent in the pr ocess. An example of the join op eration is sho wn in Figur e 10.4: Overlapping Sur faces (p.252) and Fig- ure 10.5: Connec ted Sur faces A fter Join (p.252).The o verlapping ar ea of the fac e zones is separ ated based on the par amet ers sp ecified and mer ged in to a single separ ated fac e zone af ter the join op eration. The joined sur faces will b e lo cally r emeshed .The multi-c onnec ted fac es indic ate tha t the z ones ar e no w connec ted. 251Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Connec ting O bjec tsFigur e 10.4: Overlapping S urfaces Figur e 10.5: Connec ted S urfaces A fter J oin An example of the in tersec t op eration is sho wn in Figur e 10.6: Intersec ting Sur faces (p.253) and Fig- ure 10.7: Connec ted Sur faces A fter In tersec t (p.253).The in tersec ting fac es ar e mar ked based on the paramet ers sp ecified .The in tersec ting fac e zones ar e connec ted and lo cally r emeshed . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 252Objec t-Based Sur face MeshingFigur e 10.6: Intersec ting S urfaces Figur e 10.7: Connec ted S urfaces A fter In tersec t Imp ortant After an y Join or Intersec t operation, remesh is c alled aut oma tically.To disable the p ost- remesh op eration, use one of the t ext commands: /objects/join-intersect/controls/remesh-post-intersection? no /boundary/remesh/controls/intersect/remesh-post-intersection? no The f ollowing options ar e available f or c onnec ting objec t zones: 10.4.1. Using the J oin/In tersec t Dialog Box 10.4.2. Using the J oin D ialog Box 10.4.3. Using the In tersec t Dialog Box 253Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Connec ting O bjec ts10.4.1. Using the Join/In tersec t Dialo g Box The Join/In tersec t dialo g box is acc essed fr om the c ontext-sensitiv e menu under an y Mesh O bjec t, or an y Face Zone L abels under a Mesh O bjec t. For b est r esults , the f ollowing pr actices ar e highly recommended: •Prepar e clean input pr ior t o using Join/In tersec t: –Resolv e free, duplic ate and sliv er fac es using the Diagnostics tools. See Diagnostic Tools (p.247). –Iden tify self-pr oximit y locations and separ ate it in to diff erent zones using the Diagnostics tools. –Remo ve gaps b etween the fac e zones t o be joined t o get clean c ontacts (o verlaps). Alternatively, cho ose Absolut e Toler anc e with a v alue gr eater than or equal t o the k nown gap if joining o ver smaller gaps . –Have similar mesh siz es (densit y) on fac e zones t o be joined . •If wr app ed meshes ar e used with Join, use the High option t ogether with a sc aled Size Func tion to pr oduce a very fine mesh. After join, all the sur faces ma y be remeshed with the default siz e func tion. The Join/In tersec t dialo g box can b e used as f ollows: 1. Selec t Join/In tersec t... from the c ontext-sensitiv e menu a vailable f or the Mesh O bjec t selec ted in the tree to op en the Join/In tersec t dialo g box.The c orresponding Face Zone L abels and Face Zones are listed. Note Face Zone L abel represen ts either the c ollec tive name of the fac e zones in the mesh objec t or, in the c ase of c onformal fac eted imp ort with one objec t per par t, the b odies of the par t. 2. Choose Join or Intersec t in the Operation group b ox. Tip Always use the join op eration first , then in tersec t. a. For the Join operation, Skip B ad J oins is enabled b y default (in the Controls group b ox). b.Specify an appr opriate value f orMin. Dihedr al A ngle . The Skip B ad J oins option enables joined pairs t o be undone lo cally if a self in tersec tion is found or if the smallest dihedr al angle is less than the sp ecified v alue . 3. In the Paramet ers group b ox, specify the decision thr esholds f or Angle (default is 40 degr ees) and Toler anc e (default is r elative toler ance of 0.05, or 5% of lo cal tr iangle siz e). Check Absolut e Toler anc e to sp ecify t oler ance is in the same dimensional units as the geometr y. 4. Use the global Join (Intersec t), under the Face Zones list, to perform the selec ted Operation on selec ted Face Zones using the sp ecified Paramet ers. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 254Objec t-Based Sur face MeshingAlternatively, use Local controls t o perform the op erations on pairs of o verlapping or in tersec ting face zones . Local is r ecommended f or geometr y wher e you do not k now the t oler ances. Note Length sc ales of geometr ic features should b e smaller than the lo cal tr iangle siz e. a. Click Find P airs in the Local group b ox. b.Click First (and subsequen tly Next) to step thr ough each pair of sur faces individually .The displa y is aut oma tically limit ed t o the ar ea of o verlap/in tersec tion sinc e Bounded View is enabled b y default. c.Click Mark Faces to view the o verlapping/in tersec ting fac es. d.Click Join (or Intersec t) in the Local group b ox to perform the selec ted Operation on the selec ted pair of sur faces. Imp ortant •Since the join op eration separ ates the t wo overlapping fac e zones and k eeps only one separ ated fac e zone , it is p ossible tha t the separ ated z one ma y overlap with a thir d zone , so y ou should r epeat the op eration it eratively un til no o verlaps ar e found .The in tersec tion operation do es not separ ate the fac e zones; still, it is a go od pr actice to repeat the op eration iteratively un til no in tersec tions ar e found . •The sur face should b e insp ected f or self-in tersec tions , duplic ates, and so on af ter Join or Intersec t operations using the Diagnostics tools. Imp ortant Quads ar e not supp orted b y Join or Intersec t. 10.4.2. Using the Join Dialo g Box Use the Join dialo g box to join o verlapping fac e zones based on selec tions in the gr aphics windo w. 1. Selec t the o verlapping fac e zones in the gr aphics windo w and click . Alternatively, use the hot-k ey Ctrl+T to invoke the misc ellaneous t ools and then Ctrl+J to op en the Join dialo g box. 2. Specify an appr opriate Toler anc e (default is r elative toler ance of 0.05, or 5% of lo cal siz e). Alternatively, enable Absolut e Toler anc e and sp ecify a v alue gr eater than or equal t o the k nown gap . 3. Click Mark. After verifying the mar ked fac es, selec t the fac e zones t o be joined again. 4. Click Join. 255Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Connec ting O bjec tsClick Undo if the r esults of the join op eration ar e unsa tisfac tory.The op eration c an b e undone until the ne xt mesh op eration or un til the Join dialo g box is closed . 10.4.3. Using the Intersec t Dialo g Box Use the Intersec t dialo g box to in tersec t fac e zones based on selec tions in the gr aphics windo w. 1. Selec t the in tersec ting fac e zones in the gr aphics windo w and click . Alternatively, use the hot-k ey Ctrl+T and then Ctrl+I to op en the Intersec t dialo g box. 2. Specify an appr opriate Toler anc e (default is r elative toler ance of 0.05, or 5% of lo cal siz e). Alternatively, enable Absolut e Toler anc e and sp ecify the absolut e value . 3. Enable Separ ate if you need t o separ ate the in tersec ting z ones a t the edge lo op of in tersec tion. 4. Retain the default selec tion of Ignor e Parallel F aces and en ter an appr opriate value f or Parallel A ngle . The default v alue is 5. 5. Click Mark. After verifying the mar ked fac es, selec t the fac e zones t o be intersec ted again. 6. Click Intersec t. Click Undo if the r esults of the in tersec t op eration ar e unsa tisfac tory.The op eration c an b e undone until the ne xt mesh op eration or un til the Intersec t dialo g box is closed . 10.5. Advanc ed Options Objec ts define the domain t o be meshed .The f ollowing ad vanced options ar e available: 10.5.1. Objec t Managemen t 10.5.2. Remo ving G aps B etween M esh O bjec ts 10.5.3. Remo ving Thick ness in M esh O bjec ts 10.5.4. Sewing O bjec ts 10.5.1. Objec t Managemen t The Manage O bjec ts dialo g box contains the f ollowing tabs: •Definition : Used t o create, mo dify, or delet e objec ts. •Operations : Used f or manipula tions such as mer ge, extract edges , create gr oups , and separ ate fac es. •Transf ormations : Used t o rotate, scale or tr ansla te objec ts. Right-click on Model in the tr ee and selec t Objec t Managemen t... from the menu t o acc ess the Manage O bjec ts dialo g box.See Using the M anage O bjec ts D ialog Box (p.232). Note When the fac e zones and/or edge z ones c ompr ising an objec t are delet ed, the objec t definition will b e up dated. If all the z ones asso ciated with an objec t are delet ed, the empt y objec t will b e delet ed as w ell. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 256Objec t-Based Sur face Meshing10.5.2. Remo ving G aps B etween M esh O bjec ts Gaps b etween mesh objec ts can b e remo ved using the options in the Remo ve Gaps dialo g box.The gaps c an b e between sur faces (fac e-fac e) or b etween a sur face and an edge (fac e-edge). 1. Right click on the objec t in the Outline View. Selec t Advanc ed → Remo ve Gaps ... from the c ontext sensitiv e menu . 2. Selec t Remo ve Gaps B etween O bjec ts in the Operation list. 3. Specify an appr opriate value f or the Min. Gap D istanc e,Max. Gap D istanc e, and Percentage M argin. 4. Specify an appr opriate value f or Critical A ngle .The cr itical angle is the maximum angle b etween the faces c onstituting the gap t o be remo ved. 5. Ignor e Or ientation is enabled b y default. If the thick ness of an y of the objec t selec ted is less than the Max. Gap D istanc e, then y ou c an disable Ignor e Or ientation . In this c ase the or ientations of the nor mals will b e consider ed. Ensur e tha t, the nor mals in the gaps t o be remo ved ar e appr opriately or iented ( Fig- ure 10.8: Orientation of N ormals in G ap (p.257)). Figur e 10.8: Orientation of N ormals in G ap 6. Selec t the appr opriate option f or feature edge e xtraction ( none ,feature, or all) and sp ecify the Extract Angle to be used . 7. Selec t the t ype of gap in the Gap Type list ( Face-Face or Edge-F ace). 257Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Advanced Options• For fac e-fac e gap r emo val, selec t the appr opriate option f or pr ojec tion in the Order list. You c an choose t o pr ojec t the fac es to the objec t of higher pr iority (Low To High P riority) or t o the objec t of lo wer pr iority (High t o Low P riority). 8. Click Mark to see the fac es mar ked f or pr ojec tion. 9. Click Remo ve to remo ve the gaps b etween the objec ts selec ted. Figur e 10.9: Remo ving G aps B etween O bjec ts—F ace-Face Option (p.258) sho ws an e xample wher e a face-fac e gap b etween mesh objec ts has b een r emo ved. Figur e 10.9: Remo ving G aps B etween O bjec ts—F ace-Face Option Figur e 10.10: Remo ving G aps B etween O bjec ts—F ace-Edge Option (p.258) sho ws an e xample wher e a face-edge gap b etween mesh objec ts has b een r emo ved. Figur e 10.10: Remo ving G aps B etween O bjec ts—F ace-Edge Option 10.5.3. Remo ving Thick ness in M esh O bjec ts The thick ness acr oss a mesh objec t can b e remo ved b y pr ojec ting the close sur faces to a mid-sur face. During the thick ness r emo val op eration, the objec t fac e zones will b e separ ated in or der t o pr ojec t the close sur faces to the mid-sur face and the separ ated z ones will b e mer ged back af ter the pr ojec tion. The options f or thick ness r emo val ar e available in the Remo ve Gaps dialo g box. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 258Objec t-Based Sur face MeshingConfigur ations c an b e distinguished as gaps or thick nesses based on the or ientation of the nor mals on the mesh objec t (Figur e 10.11: Gap and Thick ness C onfigur ations (p.259)).The nor mals acr oss a gap configur ation p oint toward each other , while f or a thick ness c onfigur ation, the nor mals p oint away from each other . Figur e 10.11: Gap and Thick ness C onfigur ations When using the option f or thick ness r emo val, ensur e tha t the objec t nor mals ar e appr opriately or iented dep ending on the c onfigur ations t o be remo ved (see Figur e 10.11: Gap and Thick ness C onfigur a- tions (p.259)). The gener ic pr ocedur e for remo ving thick ness in objec ts using the Remo ve Gaps dialo g box is as follows: 1. Right click on the objec t in the Outline View. Selec t Advanc ed → Remo ve Gaps ... from the c ontext sensitiv e menu . 2. Selec t Remo ve Thick ness In O bjec ts in the Operation list. 3. Specify an appr opriate value f or the Max. Gap D istanc e and Percentage M argin. 4. Specify an appr opriate value f or Critical A ngle .The cr itical angle is the maximum angle b etween the faces c onstituting the thick ness t o be remo ved. 5. Selec t the appr opriate option f or feature edge e xtraction ( none ,feature, or all) and sp ecify the Extract Angle to be used . 6. Click Remo ve to remo ve the thick ness in the objec ts selec ted. Note The thick ness r emo val op eration in volves separ ation and mer ging back of fac e zones , which ma y aff ect the mesh qualit y. It is r ecommended tha t you sa ve the mesh b efore proceeding . 259Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Advanced OptionsFigur e 10.12: Remo ving Thick ness in O bjec ts (p.260) sho ws an e xample wher e the thick ness in the mesh objec t has b een r emo ved. Figur e 10.12: Remo ving Thick ness in O bjec ts 10.5.4. Sewing O bjec ts The sewing op eration is a fac e connec ting op eration applic able t o mesh objec ts. Disconnec ted assem- blies c an b e connec ted t o cr eate the c onformal, triangular sur face mesh on the sp ecified objec ts.This operation cr eates c onformal mesh b etween b odies and pr oduces a t opology-verified mo del. Normals are also r eoriented suitably f or fur ther pr ism meshing . The pr ocedur e to Sew objec ts is: 1. Selec t the mesh objec ts in the Outline View. Right-click and selec t Advanc ed → Sew... from the c ontext sensitiv e menu . 2. Ensur e tha t the mesh objec ts for the sew op eration ar e selec ted in the Objec ts list in the Sew dialo g box. 3. Specify the name f or the mesh objec t to be created f or the selec ted mesh objec ts. 4. If desir ed, disable the Impr ove option. If disabled , you ma y need t o impr ove the sur face mesh qualit y of the mesh objec t created using the options in the Diagnostic Tools dialo g box and the Impr ove dialo g box. Figur e 10.13: Mesh O bjec ts to be Connec ted (p.261) sho ws an e xample with disc onnec ted mesh objec ts. The sewing op eration cr eates the c onformal sur face mesh b y connec ting the individual objec ts in to a single mesh objec t (Figur e 10.14: Mesh O bjec t Created b y Sewing (p.261)). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 260Objec t-Based Sur face MeshingFigur e 10.13: Mesh O bjec ts to be Connec ted Figur e 10.14: Mesh O bjec t Created b y Sewing 261Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Advanced OptionsA fac e zone gr oup is aut oma tically cr eated f or the mesh objec t created b y the Sew operation. This face zone gr oup is pr efixed b y _mesh_gr oup , and enables easy selec tion of mesh objec t fac e zones for v arious op erations (impr ove, smo oth, and so on). Note The sew op eration is not needed f or a single mesh objec t, or flo w volume (only) e xtraction type pr oblems .You c an use the options in the Diagnostic Tools dialo g box and then use the Impr ove dialo g box or the c ommand /objects/improve-object-quality to impr ove the sur face mesh (see Impr oving the M esh O bjec ts (p.338)). You c an use the c ommand /objects/sew/sew to connec t the mesh objec ts. Specify the objec ts to be connec ted and the name f or the mesh objec t to be created. 10.5.4.1. Resol ving Thin R egions Surfaces in close pr oximit y constitut e thin r egions in the mesh. Examples of thin r egions include shar p corners , trailing edge c onfigur ations , and so on, which ma y not b e recovered accur ately enough during the sewing op eration and sur face elemen ts ma y span b etween no des on the pr oximal sur faces. You c an use the c ommand /objects/sew/set/include-thin-cut-edges-and-faces to allow b etter recovery of such c onfigur ations dur ing the sewing op eration. 10.5.4.2. Processing Slits In cases c ontaining baffles , when the shrink-wr ap metho d is used f or the objec t wr apping op eration, the mesh objec t is cr eated with near ly overlapping sur faces represen ting the baffle .Though the sur faces are near ly overlapping , ther e is a numer ically a small angle b etween them (par allel fac e angle). Such configur ations c onstitut e slits in the mesh objec t. The c ommand /objects/sew/set/process-slits-as-baffles? enables y ou t o collapse the near ly overlapping sur faces c orresponding t o the baffle when the sew op eration is p erformed t o create the mesh objec t. Specify the maximum slit thick ness r elative to the minimum siz e sp ecified and the par allel fac e angle b etween the fac es c ompr ising the slit when process-slits-as- baffles is enabled . Note When process-slits-as-baffles is enabled f or the Sew operation, it is r ecommen- ded tha t you check the mesh objec t created f or v oids or p ockets. Use the c ommand /objects/merge-voids to remo ve an y voids or p ockets cr eated in the mesh objec t (see Remo ving Voids (p.262) for details). 10.5.4.3. Remo ving Voids The c ommand /objects/merge-voids enables y ou t o remo ve voids or p ockets cr eated in the mesh objec t. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 262Objec t-Based Sur face MeshingChapt er 11: Objec t-Based Volume M eshing This chapt er descr ibes the v olume meshing appr oach with which y ou c an gener ate a t etrahedr al, hexcore, polyhedr al, or h ybrid volume mesh, with or without infla tion la yers, for mesh objec ts cr eated fr om the imp orted geometr y.You need t o cr eate a c onformally c onnec ted sur face mesh using the objec t wr apping or join/in tersec t op erations b efore gener ating the v olume mesh. See Objec t-Based Sur face M eshing (p.239) for details . The t ools t o complet e these st eps c an b e found in the c ontext-sensitiv e menus in the Outline View tree. Instr uctions ar e descr ibed in the f ollowing sec tions . 11.1. Volume M esh P rocess 11.2. Volumetr ic Region M anagemen t 11.3. Gener ating the Volume M esh 11.4. Cell Z one Options As an alt ernative, you c an use the C utCell mesher t o dir ectly cr eate a he x-dominan t volume mesh f or the geometr y based on meshing objec ts cr eated. See Gener ating the C utCell M esh (p.433) for details . 11.1. Volume M esh P rocess When the c onformal, connec ted sur face mesh is r eady, use the Outline View tr ee t o na viga te the v olume meshing w orkflow as f ollows: 1. Set up Volumetr ic Regions . Volumetr ic regions ar e finit e, contiguous domains r eady to receive a v olume mesh. You use the Comput e menu option t o initializ e the v olumetr ic regions within a mesh objec t. If you p erform operations such as mer ging or deleting , you should Valida te the r egions b efore computing the volume mesh. The Update option will r ecomput e existing v olumetr ic regions while pr eser ving names and t ypes. Tools t o comput e, update and v alida te the v olumetr ic regions , as w ell as t ools t o mo dify selec ted regions , are acc essible via the c ontext-sensitiv e menus . For a full descr iption of a vailable op erations , see Volumetr ic Region M anagemen t (p.264). 2. Fill the v olumetr ic regions c ollec tively or individually , as appr opriate. a. Right-click on an y individual v olumetr ic region and y ou c an acc ess menus t o setup Scoped P rism, Tet, or Hexcore volume meshing par amet ers, as appr opriate. Descr iptions of meshing par amet ers are found in Prism M eshing Options f or Sc oped P risms (p.393),Gener ating Tetrahedr al M eshes (p.399), and Gener ating the H excore Mesh (p.413). After setting mesh par amet ers, you c an c omput e the mesh in an individual v olumetr ic region using the Auto Fill Volume option. See Meshing R egions S elec tively U sing A uto Fill Volume (p.271). 263Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.b.To apply meshing par amet ers and c omput e the v olume mesh c ollec tively f or all v olumetr ic regions of the selec ted objec t(s), use the Auto M esh option in the Volumetr ic Regions context menu . See Meshing A ll Regions C ollec tively U sing A uto M esh (p.268). You c an also acc ess the Auto M esh option fr om the objec t level context menu , and acc ess the sc oped pr ism option dir ectly using Setup Sc oped P risms ... from the Volumetr ic Regions menu . 3. Examine the v olume mesh and v erify the mesh qualit y. a. The c omput ed v olume mesh is plac ed in to Cell Z ones .You c an use the c ontext menus t o dr aw the cell z ones individually or c ollec tively t o examine the mesh. Cell z ones ma y be mer ged or delet ed if necessar y.Volumetr ic regions ar e not aff ected if c ell z ones ar e delet ed. Refer to Cell Z one Op- tions (p.272). b.Impr ove the mesh qualit y using the Auto Node M ove tool, if needed . See Moving N odes (p.458). When y ou ar e sa tisfied with the qualit y of the v olume mesh, prepar e the mesh f or tr ansf er to solution mode. Right click on Model at the t op of the tr ee and selec t Prepar e for S olve from the c ontext menu . Operations such as deleting dead z ones , deleting geometr y objec ts, deleting edge z ones , remo ving face/cell z one name pr efixes and/or suffix es, and deleting unused fac es and no des ar e performed dur ing this op eration. Imp ortant In objec t-based w orkflows, mer ging c ell z ones r equir es tha t the y be in the same v olumetr ic region. To mer ge c ell z ones tha t cannot b e in the same v olumetr ic region b ecause the y are not contiguous , you will need t o first delet e the objec t(s) only , and then use the Manage C ell Zones dialo g box. Note When y ou gener ate a p oly mesh, node w eigh ts for no de-based gr adien ts ar e enabled b y default. For p ostpr ocessing , this setting c an impr ove the accur acy of the displa yed r esults near w all edges when y ou ar e displa ying c ontours on the p oly mesh. When y ou tr ansf er the poly mesh t o solution mo de, a message will notify y ou tha t this in terpolation is enabled . You c an disable it b y setting the /display/set/nodewt-based-interp? command to no. 11.2. Volumetr ic Region M anagemen t Volumetr ic regions ar e finit e, contiguous domains tha t are ready for v olume meshing .Volumetr ic regions are comput ed fr om the c onformal sur face mesh and ma terial p oints. If a v olumetr ic region is changed , you should v alida te or up date the r egions pr ior t o filling with the v olume mesh. You c an use the c ontext-sensitiv e menu a vailable f or Volumetr ic Regions for managing the r egions collec tively: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 264Objec t-Based Volume M eshing•Use Comput e to initializ e the r egions; Valida te to confir m the finit e, contiguous domains af ter changes; and Update to pr eser ve names and t ypes while r ecalcula ting r egions . •You c an use the Selec t Regions and External B affles sub-menus t o assist in selec ting or visualizing regions based on t ype. •Objec t-based meshing par amet ers ar e set and the v olumetr ic regions filled using the Auto M esh tool. The Setup Sc oped P risms ... tool is a dir ect link t o the Scoped P risms dialo g box. •You c an get sur face mesh sta tistics using the Summar y option, and a listing of r egion c omp osition using the Info option. Individually , you c an use the c ontext-sensitiv e menu f or a named v olumetr ic region t o mo dify and e x- amine the r egion, as w ell as set up r egional mesh par amet ers. •Use Draw,Draw Options , and List S elec tion to assist in selec ting and visualizing the r egions . •The t ools a vailable in the Diagnostics ...,Change Type,Manage , and Remesh F aces menus ar e used t o mo dify the v olumetr ic region. •You c an set up r egional mesh par amet ers using the Scoped P risms ,Tet, and Hexcore menus .The Auto Fill Volume ... tool is used t o gener ate the v olume mesh f or the individual r egion. •Delet e Cells will r emo ve an y existing v olume mesh while pr eser ving the v olumetr ic region inf ormation. •You c an get sur face mesh sta tistics using the Summar y option and the r egion's c omp osition using the Info option. The a vailable options ar e descr ibed in detail in the f ollowing sec tions . 11.2.1. Computing and Verifying R egions 11.2.2. Volumetr ic Region Op erations 11.2.1. Computing and Verifying Regions The c ontrols descr ibed her e ar e found in the c ontext-sensitiv e menu acc essed b y right-click ing on Volumetr ic Regions . Comput e Volumetr ic regions need t o be comput ed pr ior t o objec t based v olume meshing .The Comput e Regions dialo g box contains options f or computing v olumetr ic regions t o pr oduce ready to mesh domains .The computing of r egions includes t opology checks , re-or ienting of nor mals , and baffle iden tification and handling b efore gener ating the v olume mesh. The v olumetr ic region c omputa tion c an also handle o verlapping z ones , so long as the y are not multi-c onnec ted. 1. Selec t Comput e... to op en the Comput e Regions dialo g box. 265Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Volumetr ic Region M anagemen t2. Selec t the ma terial p oints in the Material P oints selec tion list and click OK. Note When r egions ar e comput ed, region names and t ypes will b e based on the fac e zone labels of the mesh objec t selec ted. If regions ar e recomput ed, all pr evious r egion names and t ypes will b e over wr itten. Valida te Volumetr ic regions must b e closed , water-tigh t domains . If individual r egions ar e mo dified af ter initially computing v olumetr ic regions , the mo dified r egions need t o be valida ted b efore pr oceeding t o volume meshing . Regions c an b e mo dified using op erations such as mer ging , deleting , or r enaming them or changing the r egion t ype. Also, the r egion ma y also b e mo dified if sc oped pr ism settings ar e applied . To manually v alida te the v olumetr ic regions , selec t Valida te. Also, the r egions will b e valida ted when the v olume mesh is gener ated. Update Some of y our mo dific ations ma y involve changing the name or t ype for the v olumetr ic region. You c an recalcula te the v olumetr ic region without aff ecting the r egion name or t ype using the Update control. Selec t Regions Connec ts to a sub-menu tha t allo ws you t o selec t multiple r egions based on t ype (fluid , solid , dead , or all). External B affles Connec ts to a sub-menu tha t allo ws you t o displa y, selec t, or r emo ve the baffle(s) fr om the v olumetr ic regions . Setup Sc oped P risms Provides dir ect acc ess t o Scoped P risms dialo g box in which y ou c an define infla tion la yers t o sp ecific entities in the mo del. Auto M esh Use this menu it em f or setting up v olume fill meshing par amet ers and c omputing the v olume mesh in the full objec t. Summar y From the Volumetr ic Regions menu , you c an use Summar y to obtain an o verall summar y with c oun ts of fac e zones , all, free, multi, and duplic ate fac es, the maximum sk ewness and numb er of fac es with skewness > 0.85. Info From the Volumetr ic Regions menu , you c an use Info to obtain a listing of all r egions with t ype, volume , material p oint, and fac e zones . 11.2.2. Volumetr ic Region Op erations The c ontext-sensitiv e menus f or individual v olumetr ic regions off er se veral options t o selec t or dr aw regions .With one or mor e regions selec ted in the tr ee: •Use the Draw menu it em t o dr aw the highligh ted r egion(s), replacing wha t was pr eviously displa yed. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 266Objec t-Based Volume M eshing•Use the Draw Options submenu t o add , remo ve, highligh t, or selec t the r egion(s) t o (fr om) the displa y. This submenu also pr ovides options t o dr aw, add , remo ve, highligh t, or selec t regions based on b oundar y type (Walls or Baffles ), interface type (Fluid-F luid interface,Fluid-S olid interface, or Solid-S olid interface), or v olume t ype (Filled Volume or Empt y Volume ). •Use the List S elec tion submenu t o add , remo ve, or selec t the r egion(s) t o (fr om) a selec tion list in a dialo g box. This submenu also pr ovides options t o selec t, add , or r emo ve regions based on b oundar y type (Walls or Baffles ), interface type (Fluid-F luid interface,Fluid-S olid interface, or Solid-S olid interface), or v olume t ype (Filled Volume or Empt y Volume ). Operations t o mo dify the selec ted v olumetr ic region(s) include the f ollowing: •Face connec tivit y and qualit y based diagnostic t ools ar e available f or fluid v olumetr ic regions . Selec t Dia- gnostics ... in the menu a vailable f or the r egion selec ted t o op en the Diagnostic Tools dialo g box. •Use the Change Type option t o change the r egion t ype in the c orresponding dr op do wn list. •Merge multiple r egions using the Manage → Merge... option in the menu . Enter the New Region N ame and selec t the t ype for the mer ged r egion in the New Region Type drop-do wn list in the Merge Regions dialo g box. Note If ther e ar e shar ed fac e zones , mer ging r egions will delet e the shar ed fac e zones . However, if ther e ar e cell z ones asso ciated with the r egions , then mer ging the r egions will not delet e the shar ed fac e zones . In this c ase, the shar ed fac e zones will b e delet ed when the c ell zones ar e delet ed. •Rename individual r egions using the Manage → Rename option in the menu . Enter the New Region N ame in the Rename Region dialo g box. •Delete regions using the Manage → Delet e option in the menu . Tip Deleting r egions ma y cause fac e zones t o be delet ed. It is r ecommended tha t the r egion type be changed t o dead inst ead of deleting the r egion. •Use the Remesh F aces option in the menu t o remesh the fac e zones based on the e xisting siz e field . Volume meshing op erations include options t o set up meshing par amet ers, fill the v olume based on the par amet ers set , and manipula te the c ell z ones in the r egions . •Use the Scoped P risms → Set... option t o op en the Scoped P risms dialo g box for setting sc oped pr ism controls. •Use the Tets → Set... option t o op en the Tet dialo g box for setting t etrahedr al mesh c ontrols. •Use the Hexcore → Set... option t o op en the Hexcore dialo g box for setting he xcore mesh c ontrols. 267Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Volumetr ic Region M anagemen t•Use the Auto Fill Volume ... option t o op en the Auto Fill Volume dialo g box to create the v olume mesh for the selec ted v olumetr ic regions based on the meshing par amet ers set. •Use the Delet e Cells option t o delet e the c ell z ones of the v olumetr ic regions . The Summar y and Info options pr int inf ormation t o the c onsole ab out the sur face mesh and the r egion's comp osition, respectively, for the selec ted v olumetr ic region(s). 11.3. Gener ating the Volume M esh When r egions ha ve been c omput ed and v erified , you c an pr oceed t o gener ate the v olume mesh. Use the pr ocess descr ibed b elow tha t is b est suit ed t o your w orkflow or pr oblem: 11.3.1. Meshing A ll Regions C ollec tively U sing A uto Mesh 11.3.2. Meshing R egions S elec tively U sing A uto Fill Volume Note The w orkflow for objec t-based v olume meshing do es not supp ort par tial meshing within a region. Operations such as pr isms gener ation only ,Tet-initializa tion only , Hexcore only , etc., requir e a domain-based w orkflow. Imp ortant In the objec t-based v olume meshing pr ocedur e, by default a back up of the sur face mesh is created b efore volume meshing star ts.To restore the sur face mesh a t an y point, selec t Rest ore Faces in the c ontext-sensitiv e menu f or the mesh objec t.When y ou selec t the Rest ore Faces option, the cur rent objec t fac e zones and c ell z ones will b e delet ed. To disable the back up, set the /mesh/auto-mesh-controls/backup-object command to no. In tha t case, you will not b e able t o restore the sur face mesh using the Rest ore Faces option. There ma y be a diff erence in the initial v olume mesh gener ated f or an objec t and tha t gen- erated af ter restoring the objec t sur face mesh due t o diff erences in the or der of z ones/en tities processed dur ing v olume meshing . 11.3.1. Meshing A ll Regions C ollec tively U sing A uto M esh The Auto M esh dialo g box contains options f or gener ating the v olume mesh f or all c omput ed v olu- metr ic regions of the mesh objec t. The v olume mesh c an b e gener ated as f ollows: 1. Open the Auto M esh dialo g box from the c ontext-sensitiv e menu a vailable b y right-click ing on an y mesh objec t or its Volumetr ic Regions or Cell Z ones branch in the tr ee. You c an also use the Mesh → Auto M esh menu it em t o op en the Auto M esh dialo g box. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 268Objec t-Based Volume M eshing2. Ensur e tha t the mesh objec t is selec ted in the Objec t drop-do wn list. Note If you op en the Auto M esh dialo g box from the c ontext-sensitiv e menu in the tr ee, the mesh objec t to which the c ell z ones , or v olumetr ic regions , belong is aut oma tically selec ted. 3. Enable/disable Keep S olid C ell Z ones and Keep D ead C ell Z ones , as r equir ed. 4. Selec t the appr opriate option in the Grow P risms drop-do wn list in the Boundar y Layer M esh group box. a. Retain the default selec tion of none if you do not need t o gr ow pr ism la yers f or the cur rent meshing appr oach. b.Selec t scoped if you w ant to sp ecify objec t-based pr ism c ontrols. Click Set... to op en the Scoped Prisms dialo g box and define the pr ism c ontrols f or the mesh objec t. Refer to Prism M eshing Options for Sc oped P risms (p.393) for details . Tip You c an sa ve your sc oped pr ism c ontrols t o a file (*.p zmc ontrol) f or use in ba tch mode, or r ead in a pr eviously sa ved sc oped pr ism file . c.Selec t zone-sp ecific if you w ant to sp ecify z one-sp ecific pr ism par amet ers. Click Set... to op en the Prisms dialo g box and sp ecify the z one-sp ecific pr ism par amet ers. Refer to Procedur e for C reating Zone-based P risms (p.369) for details . Note Poly meshing do es not supp ort zone-sp ecific pr isms . 5. Selec t the appr opriate quad-t et tr ansition elemen ts fr om the Quad Tet Transition list. Click the Set... butt on t o op en the Pyramids dialo g box or the Non C onformals dialo g box (dep ending on the selec tion) and sp ecify the appr opriate par amet ers. Refer to Creating P yramids (p.353) and Creating a N on-C onformal Interface (p.357) for details . Note The Quad Tet Transition options ar e not applic able t o poly mesh. 6. Selec t the appr opriate option fr om the Volume F ill list. Click the Set... butt on t o op en the Tet,Hexcore, or Poly dialo g box (dep ending on the selec tion). Specify the appr opriate par amet ers. Refer to Initializing 269Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Gener ating the Volume M eshthe Tetrahedr al M esh (p.406),Refining the Tetrahedr al M esh (p.407),Controlling H excore Paramet ers (p.416), and Gener ating P olyhedr al M eshes (p.423) for details . Note •The No Fill option is not a vailable when a mesh objec t is selec ted f or v olume meshing . •Some op erations such as pr isms gener ation only ,Tet-initializa tion only , Hexcore only , are not a vailable f or objec t-based v olume meshing . Similar ly, options under the Zones group in the Tet and Hexcore dialo g boxes, tha t requir e a z one-based w orkflow, have no eff ect for objec t-based v olume meshing . 7. Specify the appr opriate Volume F ill Options . a. For the Tet or Poly metho ds, set the f ollowing: •Selec t the appr opriate option f or Cell S izing . –Size Field specifies tha t the c ell siz e is det ermined based on the cur rent siz e-field . –Geometr ic specifies tha t the c ell siz e in the in terior of the domain is obtained b y a geometr ic growth fr om the closest b oundar y acc ording t o the gr owth r ate sp ecified . Set the Growth R ate requir ed. •Specify the Max C ell L ength . Click Comput e to comput e the maximum c ell siz e based on the mesh objec t. b.For the Hexcore metho d, set the f ollowing: •Selec t the appr opriate option f or Type. Retain the default selec tion of Cartesian or selec t the Octree type. •Set the numb er of Buff er L ayers and Peel L ayers. •Specify the Max C ell L ength for the C artesian appr oach. Click Comput e to comput e the maximum cell siz e based on the mesh objec t. Specify the Min C ell L ength for the O ctree appr oach. 8. Enable or disable additional Options as desir ed. • Enable Merge C ell Z ones within Regions to create a single c ell z one within a r egion, or disable t o keep the c ell z ones separ ate. 9. Click Mesh in the Auto M esh dialo g box. Alternatively, you c an use the c ommand /mesh/auto-mesh to gener ate the mesh aut oma tically. Specify a mesh objec t name f or objec t-based aut o mesh; if no name is giv en, face zone based aut o Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 270Objec t-Based Volume M eshingmesh is p erformed . Specify the mesh elemen ts to be used when pr ompt ed. Specify whether t o mer ge the c ells in to a single z one or k eep the c ell z ones separ ate. For fac e zone based meshing , specify whether t o aut oma tically iden tify the domain t o be meshed based on the t opology inf ormation. Note You c an sp ecify the meshing par amet ers f or the mesh elemen ts (pr isms , pyramids or non-c onformals , tet, or he x) using either the r espective dialo g boxes or the asso ciated text commands pr ior t o using the auto-mesh command . Commands f or p oly meshes are lo cated under the mesh/poly menu . 11.3.2. Meshing Regions S elec tively U sing A uto Fill Volume The Auto Fill Volume dialo g box contains options f or gener ating the v olume mesh in selec ted v olu- metr ic regions f or mesh objec ts. The v olume mesh c an b e gener ated as f ollows: 1. In the tr ee, expand Volumetr ic Regions and selec t the r egions t o be meshed . 2. Set up the r egional meshing par amet ers f or the selec ted r egions . a. Specify sc oped pr ism c ontrols f or the b oundar y layer mesh, if applic able . Selec t Scoped P risms → Set... in the c ontext-sensitiv e menu t o op en the Scoped P risms dialo g box. Refer to Prism M eshing Options f or Sc oped P risms (p.393) for details . b.Specify t etrahedr al mesh or he xcore mesh par amet ers, as applic able . Selec t Tets → Set... to op en the Tet dialo g box. Refer to Initializing the Tetrahedr al Mesh (p.406), and Refining the Tetrahedr al M esh (p.407) for details . Selec t Hexcore → Set... to op en the Hexcore dialo g box. Refer to Controlling H excore Para- met ers (p.416) for details . Note When y ou click the Comput e butt on in the Tet or Hexcore dialo g box, you will be ask ed if the maximum c ell siz e is t o be comput ed based on the mesh objec t selec ted. Click Yes to recomput e the c ell siz es based on the mesh objec t. Alternatively, open the Auto Fill Volume dialo g box from the menu f or the selec ted r egions . Click the Set... butt on in the Boundar y Layer M esh and Volume F ill group b ox to set the sc oped prism and t etrahedr al/he xcore mesh par amet ers, respectively. 3. Set the b oundar y layer mesh and v olume fill options in the Auto Fill Volume dialo g box. a. Enable Grow Sc oped P risms if sc oped pr ism c ontrols ha ve been set up . b.Selec t Tet or Hexcore in the Volume F ill list. 4. Click Mesh in the Auto Fill Volume dialo g box. 271Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Gener ating the Volume M eshRepeat this pr ocedur e for an y empt y volumetr ic regions un til all r egions ar e filled . 11.4. Cell Z one Options The c ontext-sensitiv e menu f or Cell Z ones contains options f or visualizing and manipula ting all c ell zones c ollec tively: •Use Draw A ll Boundar ies to dr aw all the c ell z one b oundar ies or Draw A ll Cells in R ange to dr aw all the c ells within a sp ecified r ange (f or either unr eferenced or r eferenced z ones). The r ange c an b e set in the Bounds group in the r ibbon. •Use Auto M esh... to acc ess the Auto M esh tool for v olume meshing . •Use Auto Node M ove... to acc ess the Auto Node M ove tool for impr oving the mesh qualit y by mo ving nodes. •Use the Selec t Cell Z ones sub-menu f or selec tion of all c ell z ones as w ell as selec tion b y type (fluid , solid , or dead). •Use Delet e All to delet e all c ell z ones , if needed . •Use Summar y to obtain an o verall summar y of c ell c oun t and qualit y or Info to obtain individual c ell z one type and c ell z one c oun t by type. The c ontext-sensitiv e menu f or individual c ell z ones off ers se veral options t o selec t or dr aw cell z ones . •Use Draw B oundar ies to dr aw the b oundar ies of the selec ted z ones , or Draw C ells in R ange to dr aw the cells within a sp ecified r ange . •Use the Draw Options submenu t o add , remo ve, highligh t, or selec t the c ell z one(s) t o (fr om) the displa y. •Use the List S elec tion submenu t o add , remo ve, or selec t the c ell z one(s) t o (fr om) a selec tion list in a dialo g box. •Use Auto Node M ove... to acc ess the Auto Node M ove tool for impr oving the mesh qualit y of the selec ted zone b y mo ving no des. •Use Merge to combine t wo or mor e selec ted c ell z ones in to a single z one . Imp ortant In objec t-based w orkflows, mer ging c ell z ones r equir es tha t the y be in the same v olumetr ic region. To mer ge c ell z ones tha t cannot b e in the same v olumetr ic region b ecause the y are not contiguous , you will need t o first delet e the objec t(s) only , and then use the Manage C ell Zones dialo g box. •Use Delet e to delet e the c ell z ones , if needed .Volumetr ic regions ar e not aff ected if c ell z ones ar e delet ed. •Use Summar y to obtain a summar y of c ell c oun t and qualit y or Info to obtain individual c ell z one t ype and cell z one c oun t by type. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 272Objec t-Based Volume M eshingChapt er 12: Manipula ting the B oundar y M esh The first st ep in pr oducing an unstr uctured mesh is t o define the shap e of the domain b oundar ies.You can cr eate a b oundar y mesh in which the b oundar ies ar e defined b y triangular or quadr ilateral fac ets using a pr eprocessor (GAMBIT or a thir d-par ty CAD pack age) and then cr eate a mesh in the meshing mode in F luen t.You c an also mo dify the b oundar y mesh t o impr ove its qualit y and cr eate sur face meshes on c ertain pr imitiv e shap es.The f ollowing sec tions discuss mesh qualit y requir emen ts and various t echniques f or gener ating an adequa te boundar y mesh f or numer ical analy sis. 12.1. Manipula ting B oundar y Nodes 12.2. Intersec ting B oundar y Zones 12.3. Modifying the B oundar y Mesh 12.4. Impr oving B oundar y Sur faces 12.5. Refining the B oundar y Mesh 12.6. Creating and M odifying F eatures 12.7. Remeshing B oundar y Zones 12.8. Faceted S titching of B oundar y Zones 12.9. Triangula ting B oundar y Zones 12.10. Separ ating B oundar y Zones 12.11. Projec ting B oundar y Zones 12.12. Creating G roups 12.13. Manipula ting B oundar y Zones 12.14. Manipula ting B oundar y Conditions 12.15. Creating Sur faces 12.16. Remo ving G aps B etween B oundar y Zones 12.17. Using the L oop S elec tion Tool 12.1. Manipula ting B oundar y Nodes Manipula tion of b oundar y no des is an eff ective way to influenc e the b oundar y mesh qualit y. Operations for deleting unw anted b oundar y no des c an b e performed in the Merge B oundar y Nodes dialo g box or with the asso ciated t ext commands . 12.1.1. Free and I sola ted N odes 12.1.1. Free and I sola ted N odes The mesh gener ation algor ithm do es not p ermit duplic ate no des; tha t is, two no des tha t ha ve the same C artesian c oordina tes. Duplic ate no des ma y be created b y mesh gener ators tha t preser ve the node lo cations a t adjoining edges of adjac ent sur faces, but giv e diff erent lab els t o the t wo sets of nodes.The no des and edges a t which these sur faces meet ar e termed fr ee no des and fr ee edges . 273Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Figur e 12.1: Free N odes Figur e 12.1: Free N odes (p.274) sho ws a simple geometr y in which the fr ee no des ar e mar ked. Although the no de a t the end of cur ve C1 (N12) is lo cated in the same p osition as the no de a t the b eginning of cur ve C2 (N21), each is a fr ee no de b ecause it is not c onnec ted in an y way to the adjoining cur ve. Though the no des ha ve the same lo cation, the mesher k nows only tha t the y ha ve diff erent names , and not tha t the cur ves meet a t this lo cation. Similar ly, a fr ee edge is a sur face edge tha t is used b y only one b oundar y fac e.To check the lo cation of fr ee no des, use the Displa y Grid dialo g box. Free edges ar e acc eptable when mo deling a z ero-thick ness w all (“ thin w all") in the geometr y (for e xample , Figur e 12.2: Example of a Thin Wall (p.274)). Isola ted no des ar e no des tha t are not used b y an y boundar y fac es.You c an either r etain these no des t o influenc e the gener ation of the in terior mesh (see Inser ting I sola ted N odes in to a Tet M esh (p.346)), or delet e them. Figur e 12.2: Example of a Thin Wall 12.2. Intersec ting B oundar y Zones You c an c onnec t triangular b oundar y zones in the geometr y using the set of in tersec tion op erations available .These c an b e used t o resolv e in tersec tions , overlaps , and f or c onnec ting z ones along the fr ee boundar ies. 12.2.1. Intersec ting Z ones 12.2.2. Joining Z ones Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 274Manipula ting the B oundar y Mesh12.2.3. Stitching Z ones 12.2.4. Using the In tersec t Boundar y Zones D ialog Box 12.2.5. Using S hortcut Ke ys/Icons 12.2.1. Intersec ting Z ones The in tersec t option is used t o connec t intersec ting tr i boundar y zones .Figur e 12.3: Intersec tion of Boundar y Zones (p.275) sho ws an e xample wher e the in tersec t option c an b e used .The c onnec tion is made along the cur ve (or line) of in tersec tion of the b oundar y zones .You c an use the in tersec tion operation on multi-c onnec ted fac es as w ell as in r egions of mesh siz e discr epanc y. Figur e 12.3: Intersec tion of B oundar y Zones To in tersec t boundar y zones with a gap b etween them, specify an appr opriate Toler anc e value . All zones with the distanc e between them less the sp ecified t oler ance value will b e in tersec ted.The t oler- ance can b e either r elative or absolut e.When in tersec ting z ones ha ving diff erent mesh siz es, you c an use the Refine option t o obtain a b etter gr aded mesh ar ound the in tersec ting fac es (see Figur e 12.4: In- tersec tion (A) Without and (B) With the R efine Option (p.275)). Figur e 12.4: Intersec tion (A) Without and (B) With the Refine Option 275Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Intersec ting B oundar y Zones12.2.2. Joining Z ones The join option is used t o connec t two overlapping tr i boundar y zones ( Figur e 12.5: Partially O verlapping Faces (p.276)).The o verlapping ar eas of b oth the b oundar y zones ar e mer ged and the mesh a t the boundar y of the r egion of o verlap is made c onformal. To join sur faces tha t are on t op of each other but not c onnec ted (with a small gap), specify an appr opriate Toler anc e value .The p ortion of the sur faces within the t oler ance value will b e joined .The b oundar y zone selec ted in the Intersec t Tri Zone defines the shap e of the c ombined sur face in the o verlap r egion. The shap e in the With Tri Zone ma y be changed t o perform the join op eration. Figur e 12.5: Partially O verlapping F aces Figur e 12.6: Joining of O verlapping F aces (p.277) and Figur e 12.7: Remeshing of J oined F aces (p.277) show the o verlapp ed fac es af ter joining and af ter remeshing the joined fac es. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 276Manipula ting the B oundar y MeshFigur e 12.6: Joining of O verlapping F aces Figur e 12.7: Remeshing of J oined F aces Tip In case of c omplet ely o verlapping fac e zones , you ma y need t o separ ate the z ones and then join individual pairs . In such c ases , you ma y use the /boundary/check-duplicate- geom command t o delet e the duplic ate fac e zone inst ead. 277Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Intersec ting B oundar y Zones12.2.3. Stitching Z ones The stit ch option is used t o connec t two tri boundar y zones along their fr ee edges .You c annot use this option t o connec t the sur faces a t a lo cation other than the fr ee edges in the mesh. Gaps within the giv en t oler ance ar e closed using near est p oint projec tion. Figur e 12.8: Nearest P oint Projec tion f or S titching Figur e 12.8: Nearest P oint Projec tion f or S titching (p.278) sho ws a cut thr ough the t wo sur faces,Face- 1 and Face-2 , tha t are separ ated b y a gap .The p oints of near est pr ojec tion will det ermine the lo cation of the in tersec tion cur ve.Therefore,point-1 will b e connec ted t o point-2 or point-3 . All thr ee connec t op erations allo w a small gap (within the t oler ance sp ecified) b etween the in tersec ting boundar y zones; however, the gap should not dist ort the shap e of the geometr y. Figur e 12.9: Sur faces B efore Stitch (p.278) and Figur e 12.10: Sur faces A fter S titch (p.279) sho w the sur faces before and af ter the stit ch op eration, respectively Figur e 12.9: Surfaces B efore Stitch Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 278Manipula ting the B oundar y MeshFigur e 12.10: Surfaces A fter S titch 12.2.4. Using the In tersec t Boundar y Zones D ialo g Box In gener al, all thr ee c onnec t op erations c alcula te the in tersec tion cur ve (or line) b etween the t wo surfaces to be connec ted.The in tersec tion cur ve is c onstr ucted as f ollows: •Intersec t constr ucts the cur ve as the in tersec tion of t wo zones . •Join constr ucts the cur ve as the out er b oundar y of the o verlapping r egion within the sp ecified t oler ance of the t wo sur faces. •Stitch constr ucts the cur ve along the fr ee b oundar ies and within the sp ecified t oler ance. The in tersec tion cur ve is r emeshed with a lo cal spacing c alcula ted fr om the in tersec ting sur faces.The intersec tion cur ve is inser ted in to the sur faces and will r esult in a r etriangula tion of the sur faces along the in tersec tion cur ve. The /boundary/remesh/remesh-overlapping-zones command e xtracts the b oundar y edge zones fr om the z one t o impr int.The in tersec ting cur ve is inser ted in to the z ones . During the inser tion, the z ones ar e retriangula ted. After an y connec t op eration, remesh is c alled aut oma tically.To disable the p ost-r emesh op eration, use the t ext command: /boundary/remesh/controls/intersect/remesh-post-intersection? no To perform an y of the in tersec tion op erations , do the f ollowing: 1. Selec t the b oundar y zones y ou w ant to intersec t in the Intersec t Tri Zone list. 2. Selec t the b oundar y zones with which y ou w ant to intersec t the selec ted b oundar y zone in the With Tri Zone list. 3. Selec t the appr opriate op eration fr om the Operation list. 279Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Intersec ting B oundar y Zones4. Specify the appr opriate Toler anc e value (if the sur faces ha ve a gap b etween them). 5. Enable Absolut e Toler anc e,Refine , or Separ ate as appr opriate. 6. Click Mark. The fac es tha t will b e aff ected b y the in tersec tion op eration ar e highligh ted.This also helps y ou decide whether the sp ecified t oler ance is appr opriate. 7. Click Apply . 12.2.5. Using S hor tcut K eys/Icons You c an use the Join dialo g box to join o verlapping fac e zones based on selec tions in the gr aphics windo w. Selec t the o verlapping fac e zones in the gr aphics windo w and click . Alternatively, use the hot- key Ctrl+T to in voke the misc ellaneous t ools and then Ctrl+J to op en the Join dialo g box. The detailed pr ocedur e is descr ibed in Using the Join Dialog Box (p.255). You c an use the Intersec t dialo g box to join o verlapping fac e zones based on selec tions in the graphics windo w. Selec t the o verlapping fac e zones in the gr aphics windo w and click . Alternatively, use the hot- key Ctrl+T to in voke the misc ellaneous t ools and then Ctrl+I to op en the Intersec t dialo g box. The detailed pr ocedur e is descr ibed in Using the Intersec t Dialog Box (p.256). 12.3. Modifying the B oundar y M esh Tools ar e available f or mak ing b oundar y repairs , enabling y ou t o perform pr imitiv e op erations on the boundar y mesh, such as cr eating and deleting no des and fac es, mo ving no des, swapping edges , mer ging and smo othing no des, collapsing no des, edges , and fac es, splitting fac es, and mo ving fac es to another boundar y zone . 12.3.1. Using the M odify B oundar y Dialog Box 12.3.2. Operations P erformed: Modify B oundar y Dialog Box 12.3.3. Locally R emeshing a B oundar y Zone or F aces 12.3.4. Moving N odes 12.3.1. Using the M odify B oundar y Dialo g Box This sec tion descr ibes the gener ic pr ocedur e for mo difying the b oundar y mesh using the Modify Boundar y dialo g box. In addition t o the Modify B oundar y dialo g box, you ma y also use the Displa y Grid dialo g box dur ing the mo dific ation pr ocess. 1. Displa y the b oundar y zones tha t you w ant to mo dify, using the Displa y Grid dialo g box. If you need t o modify man y zones , displa y them one a t a time t o mak e the gr aphics displa y less clutt ered. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 280Manipula ting the B oundar y Mesh2. Selec t the t ype of en tity you w ant to selec t with the mouse: edge ,node,position , and so on in the Filter list in the Modify B oundar y dialo g box. 3. Selec t the en tities y ou w ant to op erate on using the mouse-pr obe butt on (a r ight-click, by default) in the gr aphics windo w. You c an selec t individual en tities one a t a time , or selec t a gr oup of them b y defining a selec tion region. See Controlling the M ouse P robe Function (p.488) for details .The selec ted en tities will app ear in the Selec tions list in the Modify B oundar y dialo g box. 4. Click the appr opriate Operation butt on t o perform the b oundar y mo dific ation. The mesh is aut oma tically r e-displa yed af ter the op eration is p erformed , enabling y ou t o immedi- ately see the eff ect of y our change . 5. Repeat the pr ocess t o perform diff erent op erations on diff erent en tities . Warning Save the mesh p eriodically as it is not alw ays possible t o undo an op eration. 12.3.2. Op erations P erformed: Modify B oundar y Dialo g Box You c an p erform the f ollowing op erations using the Modify B oundar y dialo g box: Creating N odes To cr eate no des, do the f ollowing: 1. Selec t the r equir ed p ositions (or en ter no de c oordina tes e xplicitly in the Enter S elec tion box). 2. Selec t node in the Filter list or pr ess Ctrl+N. 3. Click Create or pr ess F5. Creating F aces To cr eate a fac e, do the f ollowing: 1. Selec t 3 or 4 no des and the optional z one . Use the hot k eys Ctrl+N and Ctrl+F to selec t no de and fac e as Filter, respectively. 2. Click Create or pr ess F5. While cr eating a fac e: •If you do not selec t a z one , the new fac e will b e in the same z one as an e xisting fac e tha t uses one of the specified no des. •If the no des y ou use t o create a fac e are used b y fac es in diff erent zones , mak e sur e tha t the new fac e is in the r ight zone . 281Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modifying the B oundar y Mesh•If you cr eate a fac e and it is in the wr ong z one , use the r ezoning f eature. Creating a Z one To cr eate a new z one , do the f ollowing: 1. Selec t zone in the Filter list (or Ctrl+Z). 2. Click Create or pr ess F5.The Create Boundar y Zone dialo g box will op en, prompting y ou f or the z one name and t ype. 3. Specify the name and z one t ype as appr opriate in the Create Boundar y Zone dialo g box. 4. Click OK.The new z one will aut oma tically b e added t o the Selec tions list in the Modify B oundar y dialo g box. Deleting a N ode/F ace/Zone To delet e the no des or fac es, do the f ollowing: 1. Selec t the no des or fac es or z ones t o be delet ed. 2. Click Delet e or pr ess Ctrl+W on the k eyboard. Mer ging N odes To mer ge no des, do the f ollowing: 1. Selec t the t wo no des t o be mer ged . 2. Click Merge or pr ess F9. Imp ortant The first no de selec ted is r etained; the sec ond no de is mer ged on to the first no de. Tip You c an mer ge multiple pairs of no des b y selec ting an e ven numb er of no des, in the c orrect order, before click ing Merge (or pr essing F9).The first and sec ond no des will b e mer ged , then the thir d and f ourth, and so on. Moving N odes To mo ve the no de t o an y position in the domain, do the f ollowing: 1. Selec t node in the filt er list (or Ctrl+N). 2. Selec t the no de y ou w ant to mo ve. 3. Choose position in the filt er list (or Ctrl+X). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 282Manipula ting the B oundar y Mesh4. Selec t the p osition c oordina tes or click the p osition in the gr aphics windo w to which y ou w ant to mo ve the selec ted no de. 5. Click Move To. To mo ve the no de b y sp ecifying the magnitude of the mo vemen t, do the f ollowing: 1. Selec t node in the filt er list (or Ctrl+N). 2. Selec t the no de y ou w ant to mo ve. 3. Enter the magnitude b y which y ou w ant to mo ve the selec ted no de. 4. Click Move By. Rezoning F aces To rezone one or mor e fac es, do the f ollowing: 1. Selec t the fac es y ou w ant to mo ve. 2. Selec t the z one t o which y ou w ant the selec ted fac es to mo ve. 3. Click Rezone (or Ctrl+O).You c an cr eate a z one if y ou need t o mo ve fac es to a new z one . Collapsing N odes/E dges/F aces To collapse no des, edges , or fac es, do the f ollowing: 1. Selec t the appr opriate Filter. 2. Selec t the t wo no des (or edges/fac es) y ou w ant to collapse . 3. Click Collapse (or Ctrl+^). While c ollapsing: •If a pair of no des is selec ted, both the no des ar e mo ved t owards each other (a t the midp oint) and c ollapsed into a single no de. •If an edge is selec ted, the t wo no des of the edge c ollapse on to the midp oint of the edge and sur rounding nodes ar e connec ted t o the newly cr eated no de. •If a tr iangular fac e is selec ted, a new no de is cr eated a t the c entroid of the tr iangle and the selec ted tr ian- gular fac e gets delet ed. Note You c an also c ollapse multiple pairs of en tities b y selec ting multiple en tities b efore click ing Collapse . Ensur e tha t an e ven numb er of en tities is selec ted.The first and the sec ond en tity will b e collapsed , then the thir d and the f ourth, and so on. 283Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modifying the B oundar y MeshSmo othing N odes To smo oth no des, do the f ollowing: 1. Selec t the no des y ou w ant to smo oth. 2. Click Smooth or pr ess F6. The no de will b e plac ed a t a p osition c omput ed fr om the a verage of the sur rounding no des. Splitting E dges To split edges , do the f ollowing: 1. Selec t the edges y ou w ant to split. 2. Click Split or pr ess F7. All fac es shar ing the edge will b e split in to two fac es. If you selec t multiple edges and the y shar e a fac e, the split op eration ma y not b e complet ed. If the face referenced b y the split op eration f or the sec ond edge has alr eady been split b y the op eration on the first edge , the sec ond split op eration will not b e possible b ecause the r eferenced fac e tha t no longer e xists . If this happ ens, redispla y the mesh and r eselec t the edge tha t was not split. In such c ases it ma y also b e easier t o split the fac e rather than the edge . Splitting F aces To split fac es, do the f ollowing: 1. Selec t the fac es y ou w ant to split. 2. Click Split or pr ess F7. Each tr iangular fac e will b e split in to thr ee fac es b y adding a no de a t the c entroid. Each quadr ilat- eral fac e will b e split in to two triangular fac es. Perform edge sw apping af ter this st ep t o impr ove the qualit y of the lo cal refinemen t. Swapping E dges To sw ap an edge of a tr iangular fac e, do the f ollowing: 1. Selec t the edges as appr opriate. 2. Click Swap or pr ess F8. If the tr iangular b oundar y fac e on which y ou p erform edge sw apping is the c ap face of a pr ism la yer, the sw apping will aut oma tically pr opaga te thr ough the pr ism la yers, as descr ibed in Edge S wapping and S moothing (p.389). Note Edge sw apping is not a vailable f or quadr ilateral fac es. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 284Manipula ting the B oundar y MeshFinding C oordinat es of the C entr oid To find the lo cation of the c entroid of a fac e or c ell, do the f ollowing: 1. Set Filter to face or cell as appr opriate. 2. Selec t the fac e or the c ell using the mouse pr obe butt on. 3. Click the Centroid butt on (or Ctrl+L). The fac e or c ell c entroid lo cation will b e pr inted in the c onsole windo w. Calculating D istanc e Between E ntities To comput e the distanc e between t wo en tities , do the f ollowing: 1. Set Filter to face,edge , or cell as appr opriate. 2. Selec t the t wo en tities . 3. Click Distanc e (or Ctrl+D). For e xample , if an edge (or fac e or c ell) and a no de ar e selec ted, the distanc e between the c entroid of the edge (or fac e or c ell) and the no de is c omput ed and pr inted t o the c onsole windo w. Projec ting N odes To reconstr uct features in the sur face mesh tha t were not c aptur ed in the sur face mesh gener ation, projec t selec ted no des on to a sp ecified line or plane . The Create Boundar y Zone dialo g box will app ear aut oma tically when y ou cr eate a new fac e zone . You c an sp ecify the name and t ype of the new z one in this dialo g box. To pr ojec t no des, do the f ollowing: 1. Define the pr ojec tion line or plane . For a pr ojec tion line , selec t two en tities and f or a pr ojec tion plane , selec t thr ee en tities . If edges , faces, or c ells ar e selec ted, their c entroidal lo cations will b e used . 2. Click Set (or Ctrl+S) and the pr ojec tion line or plane will b e sho wn in the gr aphics displa y. 3. Selec t the no des t o be pr ojec ted. 4. Click Projec t (or Ctrl+P). The selec ted no des ar e pr ojec ted on to the pr ojec tion line or plane tha t you defined with the Set operation. Simplifying B oundar y Mo dific ation The f ollowing func tions simplify the b oundar y mo dific ation pr ocess: Finding the Worst/M arked F aces You c an displa y fac es in the desc ending or der of their qualit y as f ollows: 285Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modifying the B oundar y Mesh1. To find the fac e ha ving the w orst qualit y in the mesh, selec t Qualit y Limit and click First or pr ess F11 . The w orst fac e will b e displa yed in the gr aphics windo w and its qualit y and z one ID ar e reported in the c onsole . •The longest edge of the fac e and the no de opp osite it ar e selec ted, and the displa y is limit ed t o the neighb orhood of the highly sk ewed fac e. •If the mesh has not b een displa yed, the w orst fac e, its qualit y, and the z one in which it lies will b e re- ported (in the c onsole). 2. Click Next (or the r ight-arrow key). The fac e ha ving the ne xt higher qualit y will b e displa yed in the gr aphics windo w.When y ou subsequen tly click Next, the fac e ha ving the ne xt higher qualit y (af ter tha t of the pr eviously dis- played or r eported fac e) will b e displa yed or r eported. 3. Click Reset (or the lef t-arrow key) to reset the displa y to the w orst qualit y elemen t. You c an also find the w orst fac e within a subset of z ones b y ac tivating a gr oup c ontaining the r equir ed zones using the User D efined G roups dialo g box and then click ing First.When y ou click the Next butt on af ter ac tivating a par ticular gr oup , the fac e ha ving the ne xt higher qualit y within the ac tive group will b e displa yed. (Ensur e tha t the global group is ac tivated t o ha ve all the z ones a vailable .) To displa y the mar ked fac es in succ ession, do the f ollowing: 1. Selec t Mark and click First (or F11 ) to find the first mar ked fac e. The fac e will b e displa yed in the gr aphics windo w. 2. Click Next (or the r ight-arrow key). The ne xt mar ked fac e is displa yed in the gr aphics windo w. 3. Click Reset (or the lef t-arrow key) to reset the displa y to the first mar ked fac e. You c an use the /bounday/unmark-selected-faces command (or Ctrl+U) to unmar k the faces. To impr ove the qualit y of the fac e, use the f ollowing op erations: •Use the Smooth operation t o smo oth the no de opp osite the longest fac e. •Use the Merge operation t o collapse the shor test edge of the fac e, mer ging the other t wo edges t ogether . The longer of the r emaining t wo edges is r etained , while the shor ter one is mer ged with the other edge . •Use the Swap operation t o sw ap the selec ted edge . •Use the Split operation t o refine the fac e by bisec ting the selec ted edge . If the selec ted en tities ar e not appr opriate, clear them, cho ose the appr opriate items , and p erform the desir ed op erations . Deselec ting a S elec ted E ntity Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 286Manipula ting the B oundar y MeshIf you selec t an inappr opriate en tity, you c an click on it again in the gr aphics windo w to deselec t it. You c an also selec t it in the Selec tions list in the Modify B oundar y dialo g box and click Clear .You can use F2 to deselec t all en tities selec ted. Warning Deselec t op erations ar e performed only on the it ems selec ted in the Selec tions list. Undoing an Op eration To undo an op eration, click Undo or pr ess F12 . In some c ases , a par ticular sequenc e of op erations cannot b e undone . Hence, mak e sur e tha t you sa ve the mesh p eriodically b etween the mo dific ations . Click Undo or pr ess F12 n times t o undo the last n operations . Warning The Undo operation is limit ed t o the op erations in the Modify B oundar y dialo g box (or the /boundary/modify menu). If other op erations/c ommands ar e in terleaved, the Undo operation ma y cause une xpected r esults . Note You c an also fix holes in the geometr y. Refer to Fixing H oles in O bjec ts (p.331) for details . 12.3.3. Locally Remeshing a B oundar y Zone or F aces The Zone Remesh dialo g box contains options f or remeshing fac e zones selec ted in the gr aphics windo w.To remesh fac e zones , selec t them in the gr aphics windo w and pr ess Ctrl+Shift+R to op en the Zone Remesh dialo g box. 1. Selec t the sizing sour ce (size-field or constan t-siz e). 2. Specify the f eature angle t o be pr eser ved while r emeshing the selec ted z ones . 3. Specify the Constan t Size value when the constan t-siz e metho d is selec ted. The Preview butt on allo ws you t o displa y siz e boxes to visualiz e the pr oposed c onstan t siz e. 4. Click Remesh . The Local Remesh dialo g box contains options f or remeshing mar ked fac es or fac es based on selec tions in the gr aphics windo w. Selec t the fac es in the gr aphics windo w. Press Ctrl+Shift+J for fac e mar king options . After selec ting/mar king the fac es, press Ctrl+Shift+R to op en the Local Remesh dialo g box. 1. Set the numb er of r adial la yers of fac es to be remeshed in the Rings field . 2. Specify the f eature angle t o be pr eser ved while r emeshing the selec ted fac es. 3. Selec t the sizing sour ce (geometr ic,size-field , or constan t-siz e). 4. Specify the Constan t Size value when the constan t-siz e metho d is selec ted. 287Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modifying the B oundar y MeshThe Preview butt on allo ws you t o displa y siz e boxes to visualiz e the pr oposed c onstan t siz e. 5. Click Remesh . 12.3.4. Moving N odes To sp ecify a distanc e and dir ection f or mo ving a no de using the Move Nodes dialo g box, do the f ol- lowing: 1. Selec t a Seed N ode from y our mo del. 2. Set the numb er of no des t o mo ve in the Node C oun t box. 3. Set the mo ve distanc e in the Move by box. 4. Selec t a dir ection. •Seed-N ormal mo ves all the no des in par allel t o the seed no de nor mal. •Local-N ormal mo ves each no de in the dir ection of its o wn nor mal. •Flip mo ves the no des in the opp osite dir ection. 5. Use Draw to pr eview the dir ection and distanc e selec ted. You ma y use the Boundar y Zones selec tion list and Boundar y Zone G roups list along with Draw to isola te the z one of in terest in the displa y. 12.4. Impr oving B oundar y Surfaces The qualit y of the v olume mesh is dep enden t on the qualit y of the b oundar y mesh fr om which it is gener ated.You c an impr ove boundar y sur faces to impr ove the o verall mesh qualit y. You c an impr ove the b oundar y mesh b y sp ecifying an appr opriate qualit y limit dep ending on the qualit y measur e consider ed.You c an also smo oth and sw ap fac es on the b oundar y sur faces to impr ove the mesh qualit y.You c an use the Boundar y Impr ove dialo g box to impr ove the sur faces.You c an diagnostic ally det ermine the b oundar y mesh qualit y using the Check and Skew butt ons a vailable when the Swap option is selec ted. 12.4.1. Impr oving the B oundar y Sur face Qualit y 12.4.2. Smoothing the B oundar y Sur face 12.4.3. Swapping F ace Edges 12.4.1. Impr oving the B oundar y Surface Qualit y You c an impr ove the b oundar y sur face qualit y using sk ewness , size change , asp ect ratio, or ar ea as the qualit y measur e. •For impr oving the b oundar y sur face qualit y based on sk ewness , size change , and asp ect ratio, specify the qualit y limit , the angle , and the numb er of impr ovemen t iterations . All the elemen ts ab ove the sp ecified qualit y limit will b e impr oved. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 288Manipula ting the B oundar y Mesh•For impr oving based on the ar ea, collapse fac es and then either sw ap the edges or smo oth the sur face. All faces ha ving ar ea smaller than the sp ecified minimum absolut e siz e will b e collapsed . You c an also sp ecify the minimum r elative siz e (siz e of the neighb oring en tity) to be consider ed while using the Collapse and S wap option. 12.4.2. Smoothing the B oundar y Surface Smoothing of the sur face mesh allo ws you t o control the v ariation in the siz e of the mesh elemen ts, ther eby impr oving the accur acy of the numer ical analy sis. Smoothing is cr itical in r egions of pr oximit y or regions wher e sur faces in tersec t and the accur acy of the appr oxima tions used in numer ical analy sis techniques det eriorates with r apid fluc tuations in the elemen t siz e.The smo othing pr ocedur e involves relocating of the mesh no des without changing the mesh t opology. 12.4.3. Swapping F ace Edges Edge sw apping c an b e used t o impr ove the tr iangular sur face mesh. The pr ocedur e involves check ing each pair of fac es tha t shar es an edge and iden tifying the c onnec ting diagonal tha t results in the most appr opriate configur ation of fac es within the r esulting quadr ilateral. For a fac e consider ed, if the un- shar ed no de on the other fac e lies within its minimal spher e, the c onfigur ation is c onsider ed t o be a Delauna y viola tion and the edge is sw app ed.The pr ocedur e mak es a single pass thr ough the fac es to avoid c yclic sw apping of the same set of edges .Thus, the edge sw apping pr ocess is r epeated un til no further impr ovemen t is p ossible . At this stage , even if a f ew D elauna y viola tions e xist, the diff erences resulting fr om c ontinual sw apping ar e mar ginal. Imp ortant If the tr iangular b oundar y zone selec ted is the c ap fac e zone of a pr ism la yer, the edge swapping will aut oma tically pr opaga te though the pr ism la yers. 12.5. Refining the B oundar y M esh To use r efinemen t regions f or lo cal refinemen t in some p ortion of the domain (f or e xample , to obtain a high mesh r esolution in the w ake of an aut omobile), you ma y refine the asso ciated b oundar y zones as w ell.When y ou p erform the lo cal refinemen t, the b oundar y fac es tha t border the r efinemen t region will not b e refined . It is ther efore possible tha t you will ha ve a jump in fac e siz e wher e a small c ell touches a lar ge b oundar y fac e.To impr ove the smo othness of the mesh, use the Refine B oundar y Zones dialo g box to appr opriately r efine the b oundar y zones tha t border the r efinemen t region b efore performing the r efinemen t of the v olume mesh. Boundar y refinemen t can b e performed only on tr ian- gular b oundar y zones . 12.5.1. Procedur e for R efining B oundar y Zones 12.5.1. Procedur e for Refining B oundar y Zones To refine b oundar y zones based on mar ked fac es, do the f ollowing: 1. Open the Refine B oundar y Zones dialo g box. Boundar y → Mesh → Refine ... 289Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Refining the B oundar y Mesh2. Selec t Mark in the Options list and define the r efinemen t region. Click the Local Regions ... butt on t o open the Boundar y Refinemen t Region dialo g box. Define the r efinemen t region as appr opriate. 3. Selec t the z ones t o be refined in the Tri Boundar y Zones list. 4. Selec t the r egion t o be refined in the Regions list. The Max F ace Area will b e up dated based on the value sp ecified in the Boundar y Refinemen t Region dialo g box. 5. Click Apply to mar k the fac es to be refined . The fac es in the selec ted z ones ha ving fac e ar ea gr eater than the Max F ace Area specified will be mar ked. 6. Selec t Refine in the Options list and Mark in the Refinemen t group b ox. 7. Click Apply . The mar ked fac es ar e refined b y dividing them in to thr ee fac es: Figur e 12.11: Refining a Triangular B oundar y Face To refine b oundar y zones based on pr oximit y, do the f ollowing: 1. Open the Refine B oundar y Zones dialo g box. Boundar y → Mesh → Refine ... 2. Selec t Refine in the Options list and Proximit y in the Refinemen t group b ox. 3. Selec t the z one fr om which the pr oximit y is t o be det ermined in the Tri Boundar y Zones selec tion list. 4. Specify the Rela tive Distanc e and numb er of r efinemen t iterations as appr opriate. 5. Click Apply . The fac es in the pr oximit y of the sp ecified z one ar e refined as sho wn her e: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 290Manipula ting the B oundar y MeshFigur e 12.12: Boundar y M esh (A) B efore and (B) A fter Refining B ased on P roximit y To fur ther impr ove the qualit y of the r efined b oundar y mesh, do the f ollowing: 1. Selec t Swap in the Options list and sp ecify the Max A ngle and Max S kew as appr opriate (use the Refine Boundar y Zones dialo g box). See Swapping (p.452) for details ab out sw apping . 2. Click Apply . 3. If the geometr y of the b oundar y is close t o planar , you c an impr ove the mesh qualit y fur ther b y selec ting the Smooth option, specifying the Max A ngle1 and Relax2 par amet ers, as appr opriate (in the Refine Boundar y Zones dialo g box), and click ing Apply . Warning If the geometr y is far fr om planar , smo othing is not r ecommended as it ma y mo dify the shap e of the b oundar y. If you w ant to repeat the pr ocess f or another r efinemen t region, first selec t the Clear option and click Apply to clear all mar ks. 12.6. Creating and M odifying F eatures Boundar y → Mesh → Feature... Geometr ic features, such as r idges , cur ves, or c orners should b e pr eser ved while p erforming v arious operations (f or e xample , smo othing , remeshing) on the b oundar y mesh. You c an cr eate edge z ones f or a fac e zone and if r equir ed, you c an also mo dify the no de distr ibution on the edge z one .The Feature Modify dialo g box contains options a vailable f or cr eating and mo difying edge z ones .You c an also dr aw the edge z ones t o det ermine their dir ection (tha t is, det ermine the star t and the end p oints). 1Max A ngle sp ecifies the maximum angle b etween t wo adjac ent fac e nor mals .When the Swap option is ac tive, only fac es with an angle below this v alue will b e sw app ed.This r estriction pr events the loss of shar p edges in the geometr y.The v alid r ange of en tries is 0 t o 180° and the default is 10°. The lar ger the angle , the gr eater the chanc e tha t a fac e sw ap will o ccur tha t ma y ha ve an impac t on the flo w solution. 2Relax sp ecifies the r elaxa tion fac tor b y which the c omput ed change in no de p osition should b y multiplied b efore the no de is mo ved. A value of z ero results in no no de mo vemen t, and a v alue of 1 r esults in mo vemen t equiv alen t to the en tire comput ed incr emen t. 291Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Creating and M odifying F eatures12.6.1. Creating E dge Z ones 12.6.2. Modifying E dge Z ones 12.6.3. Using the F eature Modify D ialog Box Imp ortant •For objec t-based meshing , you c an use the c ontext menus in the tr ee or onscr een t ools t o create edge z ones on selec ted fac e zones or sur faces.These options use the F ixed angle cr iterion. See Extract Edge Z ones (p.327). •You c an also use the Surface Retr iangula tion dialo g box for cr eating edge z ones b efore remeshing the fac e zones .The Surface Retr iangula tion dialo g box allo ws you t o use the fac e- zone appr oach only . 12.6.1. Creating E dge Z ones Edge z ones c an b e created acc ording t o the sp ecified c ombina tion of the edge z one cr eation appr oach and the angle cr iterion. The angle cr iteria used f or cr eating edge z ones ar e as f ollows: •Fixed angle cr iterion This metho d considers the f eature angle b etween adjac ent fac es when cr eating edge z ones .You can sp ecify the minimum f eature angle b etween adjac ent fac es as a par amet er for edge z one cr eation. The c ommon edge thr ead b etween t wo fac es will b e created when the f eature angle is gr eater than the v alue sp ecified . •Adaptiv e angle cr iterion This metho d compar es the angle a t the edge with the angle a t neighb oring edges . If the r elation between the angles ma tches the t ypic al pa tterns of the angles in the neighb orhood of the f eature edge , the edge in question is c onsider ed t o be a f eature edge .You do not need t o sp ecify a v alue for the f eature angle in this c ase. The appr oaches a vailable f or edge z one cr eation ar e as f ollows: •Face zone appr oach The edge thr ead is cr eated on the en tire fac e zone based on the sp ecified angle cr iteria.The fac e zone appr oach is useful when cr eating edge thr eads on c ommon edges wher e two sur faces of the zone in tersec t each other .The c ommon edge is c onsider ed t o be a f eature edge when the angle value sp ecified (fix ed angle cr iterion) is less than the f eature angle . Alternatively, the edge thr ead at the c ommon edge c an b e created b y det ecting the change in the f eature angle aut oma tically (adaptiv e angle cr iterion). •Face seed appr oach The edge thr ead is cr eated sur rounding the sur face on which the seed fac e is defined based on the specified angle cr iteria.The c ommon edge is c onsider ed t o be a f eature edge when the angle v alue specified (fix ed angle cr iterion) is less than the f eature angle . Alternatively, the edge thr ead a t the Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 292Manipula ting the B oundar y Meshcommon edge c an b e created b y det ecting the change in the f eature angle aut oma tically (adaptiv e angle cr iterion). The Face Seed appr oach is a vailable only when y ou use the Feature M odify dialo g box for cr eating edge z ones . If you use the Surface Retr iangula tion dialo g box inst ead, the Face Zone appr oach is used f or cr eating the edge z ones . Figur e 12.13: Surface M esh - F eature Angle = 60 Figur e 12.13: Sur face M esh - F eature Angle = 60 (p.293) sho ws a sur face mesh with t wo fac es c onnec ted at a c ommon edge and ha ving a f eature angle of 60 degr ees. Both fac es ar e in the same fac e zone . Figur e 12.14: Edge Z one f or F ace Zone A pproach and F ixed A ngle = 65 (p.293) and Figur e 12.17: Edge Zones f or F ace Seed A pproach and F ixed A ngle = 55 (or A daptiv e Angle) (p.295) sho w the edge z ones created f or diff erent combina tions of appr oach and angle cr iterion. •Figur e 12.14: Edge Z one f or Face Zone A pproach and F ixed A ngle = 65 (p.293) sho ws the single edge z one created b y using the Face Zone appr oach and Fixed angle cr iterion, with the angle sp ecified as 65 degr ees. The edge thr ead a t the c ommon edge is not cr eated as the sp ecified v alue f or Angle is gr eater than the feature angle . Figur e 12.14: Edge Z one f or F ace Zone A ppr oach and F ixed A ngle = 65 293Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Creating and M odifying F eatures•Figur e 12.15: Edge Z ones f or Face Zone A pproach and F ixed A ngle = 55 (or A daptiv e Angle) (p.294) sho ws the edge z ones cr eated b y using the Face Zone appr oach and Fixed angle cr iterion, with the angle sp ecified as 55 degr ees.The in terior edge thr ead a t the c ommon edge is cr eated b ecause the sp ecified v alue f or Angle is smaller than the f eature angle . Alternatively, if you use the Adaptiv e angle cr iterion, the change in angle will b e det ected aut oma tically and the in terior edge thr ead will b e created as sho wn in Fig- ure 12.15: Edge Z ones f or Face Zone A pproach and F ixed A ngle = 55 (or A daptiv e Angle) (p.294). Figur e 12.15: Edge Z ones f or F ace Zone A ppr oach and F ixed A ngle = 55 (or A daptiv e Angle) •Figur e 12.16: Edge Z one f or Face Seed A pproach and F ixed A ngle = 65 (p.294) sho ws the single edge z one created b y using the Face Seed appr oach and Fixed angle cr iterion, with the angle sp ecified as 65 degr ees. The edge thr ead a t the c ommon edge is not cr eated b ecause the sp ecified v alue f or Angle is gr eater than the f eature angle . Figur e 12.16: Edge Z one f or F ace Seed A ppr oach and F ixed A ngle = 65 •Figur e 12.17: Edge Z ones f or Face Seed A pproach and F ixed A ngle = 55 (or A daptiv e Angle) (p.295) sho ws the edge z ones cr eated b y using the Face Seed appr oach and Fixed angle cr iterion, with the angle sp ecified as 55 degr ees.The b oundar y edge thr ead is cr eated based on the seed fac e selec ted.The in terior edge thread a t the c ommon edge is cr eated b ecause the sp ecified v alue f or Angle is smaller than the f eature Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 294Manipula ting the B oundar y Meshangle . Alternatively, if you use the Adaptiv e angle cr iterion, the change in angle will b e det ected aut oma t- ically and the b oundar y and in terior edge thr eads will b e created as sho wn her e: Figur e 12.17: Edge Z ones f or F ace Seed A ppr oach and F ixed A ngle = 55 (or A daptiv e Angle) 12.6.2. Modifying E dge Z ones The f ollowing edge mo dific ation options ar e available: •Deleting edge z ones . •Copying e xisting edge z ones (including the no des) t o a new edge z one . •Toggling the edge z one t ype between b oundar y and in terior. •Grouping and ungr ouping edge z ones . •Orienting the edges on the edge z one t o point in the same dir ection. •Reversing the dir ection of the edge z one . Note The dir ection of a b oundar y edge z one det ermines the side fr om which new fac es ar e formed .The dir ection of a b oundar y edge z one should b e right-handed with r espect to the a verage nor mal of the fac e zone t o be remeshed . However, the dir ection is not so imp ortant in the c ase of in terior edge z ones b ecause fac es ar e alw ays formed on b oth sides of the z one . •Separ ating the edge z one based on the c onnec tivit y and f eature angle sp ecified . 295Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Creating and M odifying F eatures•Merging multiple edge z ones in to a single z one . Note Only edge z ones of the same t ype (b oundar y or in terior) c an b e mer ged . •Remeshing the edge z ones t o mo dify the no de distr ibution. •Projec ting the edges of the edge z one on to a fac e zone . You c an selec t the closest p oint metho d or sp ecify the dir ection in which the edge should b e pr o- jected on to the selec ted fac e zone . •Intersec ting edge z ones t o create a new edge z one c ompr ising the c ommon edges . 12.6.3. Using the F eature M odify D ialo g Box The Feature M odify dialo g box can b e used f or cr eating edge z ones as f ollows: 1. Selec t the r equir ed z ones fr om the Boundar y Zones selec tion list. 2. Selec t Create from the Options list. 3. Selec t the appr opriate option fr om the Appr oach drop-do wn list. Selec t the appr opriate Seed F ace when using the Face Seed appr oach. 4. Selec t the appr opriate option fr om the Angle C riterion drop-do wn list. Specify an appr opriate value f or the Angle when using the Fixed angle cr iterion. 5. Enable Add E dges t o O bjec t to add the e xtracted edges t o the objec t compr ising the b oundar y fac e zones selec ted. 6. Click Apply to create the edge z ones . Imp ortant •For objec t-based meshing , you c an use the c ontext menus in the tr ee or onscr een t ools t o create edge z ones on selec ted fac e zones or sur faces.These options use the F ixed angle cr iterion. See Extract Edge Z ones (p.327). •You c an also use the Surface Retr iangula tion dialo g box for cr eating edge z ones b efore remeshing the fac e zones .The Surface Retr iangula tion dialo g box allo ws you t o use the fac e- zone appr oach only . The Feature M odify dialo g box can b e used f or mo difying edge lo ops as f ollows: •Operations such as deleting , copying , grouping/ungr ouping , orienting , separ ating , and mer ging edge loops, toggling the edge lo op t ype, and r eversing the edge lo op dir ection: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 296Manipula ting the B oundar y Mesh1. Selec t the appr opriate zones in the Edge Z ones selec tion list. Warning You c an selec t only one edge z one when separ ating an edge z one . 2. Click the appr opriate butt on in the Edge M odify group b ox. •Remeshing edge z ones: 1. Selec t Remesh from the Options list. 2. Selec t the appr opriate zones fr om the Edge Z ones selec tion list. 3. Selec t an appr opriate metho d from the Metho d drop-do wn list. You c an sp ecify a c onstan t spacing of no des or selec t either the ar ithmetic or the geometr ic metho d for no de spacing .You c an also selec t the Size Field option t o use the siz e field t o remesh the edge z ones . For the Constan t,Arithmetic , or Geometr ic metho ds, set the f ollowing par amet ers: a. Specify v alues f or First S pacing and Last S pacing as r equir ed. Note For the Constan t metho d, the v alue sp ecified f or First S pacing will b e the constan t no de spacing . Also, the Last S pacing option is not r elevant for the Constan t metho d and will not b e available . b.Specify an appr opriate value f or Feature Angle . c.Enable Quadr atic Rec onstr uct, if requir ed.The quadr atic r econstr uction option allo ws you t o reconstr uct the edge b y fitting a quadr atic p olynomial b etween the or iginal edge no des. Alternatively, for remeshing using the siz e field , mak e sur e the siz e field is defined as r equir ed (see Computing the S ize Field (p.217)). 4. Click Apply to remesh the edge z one . •Projec ting edge z ones: 1. Selec t Projec t from the Options list. 2. Selec t the appr opriate zones in the Edge Z ones selec tion list. 3. Selec t the appr opriate fac e zone fr om the Face Zones selec tion list. 4. Selec t the appr opriate pr ojec tion metho d from the Metho d drop-do wn list. The Closest P oint metho d sp ecifies tha t the edge should b e pr ojec ted t o the closest p oint on the fac e zone selec ted. The Specific D irection metho d allo ws you t o pr ojec t the edge on the fac e zone in a sp ecific dir ection. 297Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Creating and M odifying F eatures5. Specify the dir ection in which the edges should b e pr ojec ted when using the Specific D irection metho d. 6. Click Apply to pr ojec t the edge on to the selec ted fac e zone . •Intersec ting edge z ones: 1. Selec t Intersec t from the Options list. 2. Selec t the appr opriate zones in the Edge Z ones selec tion list. 3. Enable Delet e in the Overlapp ed E dges group b ox if y ou w ant to aut oma tically delet e all the o ver- lapping edges . You c an use the delete-overlapped-edges text command t o delet e individual o verlapping edges . 4. Specify an appr opriate value f or Intersec tion Toler anc e. 5. Click Apply to intersec t the selec ted edge z ones . 12.7. Remeshing B oundar y Zones Boundar y → Mesh → Remesh... In some c ases , you ma y need t o regener ate the b oundar y mesh on a par ticular b oundar y fac e zone . You ma y find tha t the mesh r esolution on the b oundar y is not high enough, or tha t you w ant to gen- erate triangular fac es on a b oundar y tha t cur rently has quadr ilateral fac es. Remeshing of b oundar y fac es can b e acc omplished using the Surface Retr iangula tion dialo g box. You c an r emesh the b oundar y fac e zones based on edge angle , cur vature, and pr oximit y. 12.7.1. Creating E dge Z ones 12.7.2. Modifying E dge Z ones 12.7.3. Remeshing B oundar y Face Zones 12.7.4. Using the Sur face Retriangula tion D ialog Box 12.7.1. Creating E dge Z ones To remesh a fac e zone , you first need t o cr eate edge z ones on the b orders of the fac e zones using the paramet ers a vailable in the Edge C reate group b ox in the Surface Retr iangula tion dialo g box (see Using the Sur face Retriangula tion D ialog Box (p.300)). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 298Manipula ting the B oundar y MeshYou c an cr eate the edge z ones acc ording t o your r equir emen t by sp ecifying an appr opriate combina tion of the edge z one cr eation appr oach and angle cr iteria (r efer to Creating E dge Z ones (p.292) for details). Imp ortant The Face Seed appr oach is a vailable only when y ou use the Feature M odify dialo g box for cr eating edge z ones . Click the Feature M odify ... butt on t o op en the Feature M odify dialo g box. Note •For objec t-based meshing , you c an cr eate edge z ones on selec ted fac e zones or sur faces using the c ontext menus in the tr ee or onscr een t ools.These options use the F ixed angle cr iterion. See Extract Edge Z ones (p.327). •You c an also use the Feature M odify dialo g box to create new or mo dify e xisting edge z ones before remeshing the fac e zones . You c an also dr aw the edge z ones t o det ermine their dir ection (tha t is, the star t point and the end point). 12.7.2. Modifying E dge Z ones You c an mo dify the no de distr ibution on the edge z ones using the Feature M odify dialo g box (op ened using the Feature M odify ... butt on in the Surface Retr iangula tion dialo g box). If you w ant to assign different no de distr ibutions t o two or mor e portions of an edge z one , you c an separ ate the z one based on a sp ecified f eature angle b etween c onsecutiv e edges . Separ ation is p erformed aut oma tically a t multiply-c onnec ted no des. After cr eating edge z ones using an appr opriate combina tion of the edge z one cr eation appr oach and angle cr iteria, mo dify the edge z one as r equir ed.You c an mo dify the edge z ones using the options available in the Feature M odify dialo g box. Refer to Using the F eature M odify D ialog Box (p.296) for details on using the v arious options a vailable in the Feature M odify dialo g box. It is also p ossible t o mo dify the edges of the z ones using the op erations in the Modify B oundar y dialo g box. Any edges y ou cr eate must ha ve the same dir ection as the edge z one . Imp ortant You c annot r emesh a c ontinuous edge z one .You must first separ ate it in to two or mor e non-c ontinuous edge z ones (tha t is, edge z ones with star t and end p oints). 12.7.3. Remeshing B oundar y Face Zones If the mesh r esolution on the b oundar y fac e zone is not enough, or y ou w ant to cr eate triangular fac es on a b oundar y fac e zone tha t cur rently has quadr ilateral fac es, you c an r emesh tha t boundar y fac e zone .You c an r emesh the b oundar y fac e zone using the Surface Retr iangula tion dialo g box (see Using the Sur face Retriangula tion D ialog Box (p.300) for details). 299Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Remeshing B oundar y Zones12.7.4. Using the S urface Retr iangula tion D ialo g Box The gener alized pr ocedur e for remeshing a b oundar y fac e zone using the Surface Retr iangula tion dialo g box is as f ollows: 1. Create the edge z ones as appr opriate. a. Selec t the b oundar y fac e zone f or which y ou w ant to create edge z ones in the Boundar y Face Zones selec tion list. b.Selec t the appr opriate option fr om the Angle C riterion drop-do wn list. By default , the Face Zone appr oach is used t o cr eate edge z ones .Therefore, you c an only specify the r equir ed Angle C riterion in the Surface Retr iangula tion dialo g box. If ho wever, you w ant to use Face Seed appr oach, you c an use the Feature M odify dialo g box to cr eate the edge z ones inst ead (see Creating E dge Z ones (p.292)). c.Click Create. The edge z ones cr eated will no w b e available in the Edge Z ones selec tion list. d.Selec t the appr opriate zones in the Edge Z ones selec tion list and click Draw to displa y them. The selec ted edge z ones will b e displa yed in the gr aphics windo w. If you ar e not sa tisfied with the edge z ones and y ou w ant to mo dify them, open the Feature M odify dialo g box. 2. Modify the edge z ones as r equir ed using the options a vailable in the Feature M odify dialo g box. Click the Feature M odify ... butt on t o op en the Feature M odify dialo g box. Refer to Modifying E dge Zones (p.295) for details . When y ou ar e sa tisfied with the edge z ones y ou c an pr oceed t o remesh the fac es. 3. Selec t the z one t o be remeshed in the Boundar y Face Zones list. You c an selec t only a single b oundar y fac e zone f or remeshing , unless the Use C onformal Remesh option is enabled . 4. Set the appr opriate remeshing options in the Face Remesh Options group b ox. a. Enable Size Field if you w ant to use the siz e field t o remesh the fac es. Note Edge z ones asso ciated with fac e zones ar e not r emeshed implicitly . If you ha ve feature edge z ones asso ciated with the sur face being r emeshed , you need t o remesh them b efore remeshing the fac e zones . b.Selec t the appr opriate options fr om the Rec onstr uction (Or der) drop-do wn list in the Face Remesh Options group b ox. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 300Manipula ting the B oundar y Meshc.Enable Replac e Face Zone , if requir ed. Imp ortant Remeshing c an b e performed on b oth tr iangular and quadr ilateral fac e zones . However, it will alw ays result in a tr iangular fac e zone . d.Enable Use C onformal Remesh if you w ant to conformally r emesh multiple fac e zones c onnec ted along the shar ed b oundar y. Note •This option is a vailable only when Size Field is enabled and None is selec ted in the Rec onstr uction drop-do wn list. You will b e ask ed t o comput e the siz e field or r ead a size field file . •Periodic fac e zones c annot b e remeshed using this option. • Set the minimum Corner A ngle to sp ecify the minimum angle b etween f eature edges tha t will b e pr eser ved dur ing r emeshing . Note The shar ed b oundar y between diff erent zones will b e remeshed only if all the face zones inciden t to it ar e selec ted f or c onformal r emeshing . 5. Click Remesh to remesh the fac e zones . Note Edge z ones ar e sa ved when the mesh file is wr itten. 12.8. Faceted S titching of B oundar y Zones You c an r epair sur faces ha ving in ternal cr acks or fr ee edges using the Faceted S titch option. You c an specify an appr opriate toler ance value within which the fr ee edges will b e stit ched .The Self S titch only option allo ws you t o stit ch the edges within the same b oundar y zone .The fac eted stit ching op eration is available only f or tr iangular b oundar ies. Figur e 12.18: Mesh (A) B efore and (B) A fter U sing the F aceted S titch Option (p.302) sho ws the r epair of a sur face with in ternal cr acks . 301Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Faceted S titching of B oundar y ZonesFigur e 12.18: Mesh (A) B efore and (B) A fter U sing the F aceted S titch Option The c ommand /boundary/remesh/faceted-stitch-zones enables y ou t o perform the fac eted stitching of z ones . Note Features ma y not b e main tained when using the fac eted stit ching op eration. 12.9. Triangula ting B oundar y Zones Some op erations lik e in tersec tion, joining , stit ching , and wr apping ar e available only t o triangular boundar y zones .You c an r emesh a quadr ilateral fac e zone with tr iangular fac es as sho wn in Fig- ure 12.19: Triangula ting a B oundar y Zone (p.303). You c an use the Triangula te Zones dialo g box to perform this op eration. The dialo g box includes an option t o either c opy the quad z ones and tr iangula te the c opied z ones or r eplac e the or iginal quad zones with the tr iangula ted z one . You c an also use the c ommand /boundary/remesh/triangulate to perform this op eration. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 302Manipula ting the B oundar y MeshFigur e 12.19: Triangula ting a B oundar y Zone 12.10. Separ ating B oundar y Zones There ar e se veral metho ds a vailable tha t allo w you t o separ ate a single b oundar y fac e zone in to multiple zones of the same t ype. If your mesh c ontains a z one tha t you w ant to br eak up in to smaller p ortions , you c an mak e use of these options . For e xample , if y ou cr eated a single w all z one when gener ating the mesh f or a duc t, but y ou w ant to gener ate diff erent mesh shap es on sp ecific p ortions of the w all, you will need t o br eak tha t wall z one in to two or mor e wall z ones . 12.10.1. Separ ating F ace Zones using H otkeys 12.10.2. Using the S epar ate Face Zones dialo g box 12.10.1. Separ ating F ace Zones using H otkeys You c an use the hotk ey Ctrl+Shift+S to separ ate fac es or z ones based on wha t has b een selec ted. If help t ext displa y is ac tive, a descr iption of the fac e zone separ ation options is displa yed. •If a multi-r egion fac e zone is selec ted, separ ation will b e by region. •If a single-r egion fac e zone is selec ted, separ ation will b e by angle .The angle ma y be set using the Separ ate Face Zones dialo g box. •If a fac e (or edge) is selec ted, the fac e zone (edge z one) separ ation will b e by seed . •If edge z one with fac e seed selec tion, then the fac e zone is separ ated b y edge z one . •If no other selec tion, separ ation will b e by mar ked fac es. Faces ar e mar ked using the hotk ey Ctrl+Shift+J and the mouse pr obe/fac e selec tion filt er. If help text displa y is ac tive, a descr iption of the mar king options is displa yed. •Ctrl+S mar ks individually selec ted fac es. •Ctrl+D mar ks ar eas b y flo od-filling . •Ctrl+R mar ks ar eas b y adding r ings ar ound the selec ted fac e. •Ctrl+Q mar ks fac es b y qualit y. •Ctrl+G mar ks fac es b y angle r elative to the selec ted fac e, on the en tire fac e zone . •Ctrl+L mar ks unmar ked island fac es. 303Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Separ ating B oundar y Zones•Ctrl+U unmar ks selec ted/all fac es. •Ctrl+I opens a dialo g box to set options f or mar king fac es. 12.10.2. Using the S epar ate Face Zones dialo g box There ar e six metho ds a vailable f or separ ating a b oundar y fac e zone using the Separ ate Face Zones dialo g box acc essed via Boundar y > Z one > S epar ate....They are: Separ ating Using A ngle For geometr ies with shar p corners , it is of ten easy t o separ ate fac e zones based on the signific ant angle . Faces with nor mal v ectors tha t diff er b y an angle gr eater than or equal t o the sp ecified angle value will b e plac ed in diff erent zones . For e xample , if the mesh c onsists of a cub e, and all 6 sides of the cub e ar e in a single w all z one , you would sp ecify a signific ant angle of 89°. Because the nor mal v ector for each cub e side diff ers b y 90° from the nor mals of its adjac ent sides , each of the 6 sides will b e plac ed in a diff erent wall z one . Separ ating Using R egions You c an also separ ate fac e zones based on c ontiguous r egions . For e xample , if y ou w ant to gener ate the mesh in diff erent regions of the domain using diff erent meshing par amet ers, you ma y need t o split up a b oundar y zone tha t enc ompasses mor e than one of these r egions . Separ ating based on r egion splits non-c ontiguous b oundar y fac e zones (tha t is, zones tha t are separ ated in to two or mor e isola ted groups) in to multiple z ones . This c ommand will also split z ones tha t are divided b y another fac e zone . An example c ould b e two face zones t ouching in a “T". Using this c ommand on the t op z one (f or e xample , wall-1 in Fig- ure 12.20: Face Separ ation B ased on R egion (p.305)) would split it in to two zones . However, individual faces in the c orners a t the “T" junc tion ma y be put in their o wn z ones .To check f or this pr oblem, list the new fac e zones (using the List butt on in the Boundar y Zones dialo g box), looking f or z ones with a single fac e in them. You c an then mer ge these fac es in to the appr opriate zone . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 304Manipula ting the B oundar y MeshFigur e 12.20: Face Separ ation B ased on Region Separ ating B ased on N eighb oring C ell Z ones Region separ ation will split w all-1 in Figur e 12.20: Face Separ ation B ased on R egion (p.305) into two zones r egar dless of whether the t wo regions ar e in the same c ell z one . However, neighb or-based separ ation will yield diff erent results . If both r egions ar e in the same c ell z one , wall-1 will not b e sep- arated (see Figur e 12.21: Face Separ ation B ased on C ell N eighb or (p.305)). If the y are in diff erent cell zones , the z one will b e separ ated.Thus, when neighb or separ ation is used , wall-1 will b e separ ated only if it is adjac ent to mor e than one c ell z one . If the t wo regions ar e in t wo diff erent cell z ones , then wall-1 has t wo diff erent neighb oring c ell z ones and ther efore it will b e separ ated in to two wall z ones . Figur e 12.21: Face Separ ation B ased on C ell N eighb or 305Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Separ ating B oundar y ZonesSepar ating B ased on the F ace/Element Shap e You c an also separ ate fac e zones based on the shap e of the fac es. For e xample , if a fac e zone c ontains both tr iangular and quadr ilateral fac es, you c an separ ate the z one in to two zones (one c ontaining the triangular fac es, and the other c ontaining the quadr ilateral fac es). Separ ating Using a S eed Element You c an separ ate fac e zones b y sp ecifying a fac e elemen t (in the fac e zone) as a seed fac e.You c an also separ ate diff erent fac es of a single fac e zone using this metho d.The sur face on which y ou define a seed fac e gets separ ated fr om r est of the fac e zone .You c an separ ate fac e zones using the seed fac e based on the f ollowing cr iteria: •Feature Angle C riteria This metho d enables y ou t o separ ate the sur face on which y ou ha ve defined a seed fac e from the surfaces ar ound it based on the sp ecified v alue of the f eature angle .The f eature angle is the angle between the nor mal v ectors of the c ells.To separ ate the fac e zones based on this cr iteria, do the following: 1. Selec t Seed in the Options list and Angle in the Flood Fill Options list. 2. Specify the seed elemen t in the Face Seed text en try field . Right-click the fac e you w ant to cho ose as a seed elemen t in the gr aphics windo w.The Face Seed field will b e up dated aut oma tically. 3. Specify the r equir ed f eature angle in the Angle field . 4. Click Separ ate. The sur face on which y ou defined the seed fac e will b e separ ated fr om other sur faces of the z one for which the f eature angle change is gr eater than or equal t o the sp ecified v alue . For e xample , if the mesh c onsists of a cub e, and all 6 sides of the cub e ar e in a single w all z one , specify a signific ant angle of 89° and sp ecify a seed fac e on an y one of the w alls. Because the nor mal v ector for each cube side diff ers b y 90° fr om the nor mals of its adjac ent sides , the fac e on which y ou ha ve defined a seed c ell will b e plac ed in a diff erent wall z one .Therefore, two zones will b e created, one z one will ha ve a fac e on which y ou defined a seed fac e and the sec ond z one will ha ve remaining fac es. •Edge Z one C riteria This metho d enables y ou t o separ ate the sur face, on which y ou ha ve defined a seed fac e, from the other fac es in the z one based on the e xisting edge z ones asso ciated with it. You must cr eate the edge z ones f or the giv en mesh t o use this metho d. To separ ate the fac e zones based on this cr iteria, do the f ollowing: 1. Selec t Seed in the Options list and Edge L oop in the Flood Fill Options list. 2. Specify the seed elemen t in the Face Seed text en try field . For this metho d, you will only sp ecify the seed elemen t.The Angle field will not b e available . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 306Manipula ting the B oundar y Mesh3. Click Separ ate. Imp ortant Create edge thr eads on the sur face zones again using the Surface Retr iangula tion dialo g box after p erforming ab ove op erations . Separ ating B ased on M ark ed F aces You c an separ ate fac e zones b y placing mar ked fac es in a new z one .To use this option in the Separ ate Face Zones dialo g box, explicitly define a subr egion of the domain (using the Boundar y Refinemen t Region dialo g box), then separ ate fac e zones based on whether or not each fac e in the sp ecified z one is in the selec ted lo cal region. 12.11. Projec ting B oundar y Zones Another mesh r efinemen t metho d in volves pr ojec ting the no des of one fac e zone on to another (p ossibly non-planar) fac e zone t o cr eate a new fac e zone tha t has the same c onnec tivit y as the or iginal fac e zone .This new fac e zone is cr eated af ter the pr ojec tion, and no c ell z ones ar e created.The fac e zone that is pr ojec ted is not mo dified in an y way. Projec ting a fac e zone is used mainly t o fill in gaps b y extending the domain thr ough the pr ojec tion. The or iginal c onnec tivit y is main tained af ter the pr ojec tion, with the eff ect being tha t elemen ts on the connec ted side z ones will b e str etched t o cover the pr ojec tion distanc e. Affected side z ones should then b e remeshed t o obtain r egular siz e elemen ts on them. Such a r emeshing r esults in a new side zone , after which y ou c an (and should) delet e the or iginal side z one . Finally , you c an mesh the domain to get the v olume elemen ts. 12.12. Creating G roups You c an cr eate gr oups of fac es and edges tha t will b e available in all the dialo g boxes along with the default gr oups (f or e xample , boundar y, tri, quad , and so on). The fac e and edge z ones ar e gr oup ed separ ately.The User D efined G roups dialo g box enables y ou t o define new fac e and/or edge gr oups , update existing gr oups , activate or delet e a par ticular gr oup . Although the dialo g box is op ened fr om the Boundar y menu , it c an b e used with all dialo g boxes tha t contain z one lists . Note When a user-defined gr oup is ac tivated, the wild-c ards used f or z one selec tion in all the text commands will r etur n zones c ontained in the ac tive gr oup . For e xample , the c om- mand /display/boundary-grid * will displa y all the b oundar y zones c ontained in the ac tive gr oup . For objec t based meshing (see Objec t-Based Sur face M eshing (p.239)), you c an cr eate a fac e gr oup and an edge gr oup c ompr ising the fac e zones and edge z ones included in the sp ecified objec ts using the options in the Zone G roup group b ox in the Operations tab in the Manage O bjec ts dialo g box. Addi- tionally , a fac e zone gr oup is aut oma tically cr eated when a mesh objec t is cr eated using the Sew oper- 307Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Creating G roupsation. This fac e zone gr oup is pr efixed b y _mesh_gr oup , and enables easy selec tion of mesh objec t face zones f or v arious op erations (impr ove, smo oth, and so on). For C utCell meshing , the mesher separ ates the fac e zones b y cell neighb or and cr eates a fac e zone group f or the fac e zones of each fluid c ell z one . See Gener ating the C utCell M esh (p.433) for details . Note When an objec t is delet ed along with the fac e and edge z ones c ompr ising the objec t, the corresponding gr oups will also b e delet ed. 12.13. Manipula ting B oundar y Zones Boundar y zones ar e gr oups of b oundar y fac es. Usually the gr ouping c ollec ts b oundar y fac es with the same b oundar y conditions , but fur ther sub-gr oupings ar e of ten used t o pr eser ve a shar p edge in the surface mesh or simply as an ar tifac t of the b oundar y mesh gener ation pr ocess. Each z one has a unique ID , which must b e a p ositiv e in teger .You c an use the options in the Manage Face Zones dialo g box to manipula te the fac e zones . find inf ormation ab out each z one , iden tify them, mer ge z ones or delet e them, change the b oundar y type of all fac es in a z one , rename z ones , and r otate, scale, or tr ansla te zones . •Click List to obtain inf ormation ab out the selec ted fac e zones .The z one ID , name , boundar y type, and numb er of fac es b y type (tr i or quad) will b e reported. •Use the Change Type option t o change the b oundar y type of the selec ted fac e zones . Note When changing the b oundar y type of an y zone t o type interior , ensur e tha t ther e is a single c ell z one acr oss the interior boundar y. Retaining multiple c ell z ones acr oss an interior boundar y can c ause undesir able r esults with fur ther t et meshing or smo othing operations . Also, face zones ha ving no/one neighb oring c ell z one should not b e changed t o type interior . The mesh check will issue a w arning if multiple c ell z ones ar e main tained acr oss an in- terior boundar y.The b oundar y type in such c ases should b e set t o internal inst ead. •Use the Copy option t o copy the no des and fac es of the selec ted fac e zones . •Use the Delet e option t o delet e the selec ted fac e zones .You c an optionally delet e the no des of the fac e zones as w ell (enabled b y default). •Use the Merge option t o mer ge the selec ted fac e zones based on Alphab etic al Or der (default) or Larger Area. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 308Manipula ting the B oundar y Mesh•Use the Rename option t o rename the selec ted fac e zones .You c an optionally change the z one name pr efix as w ell. Note The z one name c an ha ve a maximum of 256 char acters. •Use the Flip N ormals option t o flip the dir ection of all fac e nor mals on the selec ted fac e zones . •Use the Orient option t o consist ently or ient the fac e nor mals on the selec ted fac e zones . •Use the Rota te option t o rotate all no des of the selec ted fac e zones thr ough the angle sp ecified . Enter the pivot and axis of r otation or use the Define option t o selec t six no des or p ositions t o define the piv ot and axis inst ead.You c an optionally cr eate a c opy inst ead of r eplacing the or iginal z ones . •Use the Scale option t o sc ale all no des of the selec ted fac e zones b y the sc ale fac tors sp ecified .You c an optionally cr eate a c opy inst ead of r eplacing the or iginal z ones . •Use the Transla te option t o transla te all no des of the selec ted fac e zones b y the tr ansla tion off sets sp ecified . Use the Define option t o selec t two no des or p ositions t o define the tr ansla tion v ector inst ead.You c an optionally cr eate a c opy inst ead of r eplacing the or iginal z ones . The hotk ey Ctrl+Shift+N opens the Change Z one P roperties dialo g box which enables y ou t o quick ly rename the selec ted z one , set the b oundar y type, and set the geometr y recovery option (lo w or high). Note When changing the b oundar y type of an y zone t o type interior , ensur e tha t ther e is a single c ell z one acr oss the interior boundar y. Retaining multiple c ell z ones acr oss an interior boundar y can c ause undesir able r esults with fur ther t et meshing or smo othing operations . Also, face zones ha ving no/one neighb oring c ell z one should not b e changed t o type in- terior . The mesh check will issue a w arning if multiple c ell z ones ar e main tained acr oss an interior boundar y.The b oundar y type in such c ases should b e set t o internal inst ead. 12.14. Manipula ting B oundar y Conditions Case files r ead in the meshing mo de also c ontain the b oundar y and c ell z one c onditions along with the mesh inf ormation. The Boundar y Conditions dialo g box enables y ou t o copy or clear b oundar y conditions assigned t o the b oundar y zones when a c ase file is r ead. •You c an c opy the b oundar y conditions fr om the z one selec ted in the With list t o those selec ted in the Without list using the Copy option. •You c an clear the b oundar y conditions assigned t o the z ones selec ted in the With list using the Clear option. 309Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Manipula ting B oundar y Conditions12.15. Creating S urfaces You c an cr eate sp ecific t ypes of sur faces within the e xisting geometr y using one of the options a vailable in the Boundar y/Create menu . The Constr uct Geometr y tool ( ) also enables y ou t o cr eate a b ounding b ox or c ylinder/fr ustum for selec ted or all z ones displa yed in the gr aphics windo w. The f ollowing sec tions e xplain ho w to cr eate sur faces. 12.15.1. Creating a B ounding B ox 12.15.2. Creating a P lanar Sur face Mesh 12.15.3. Creating a C ylinder/F rustum 12.15.4. Creating a S wept Sur face 12.15.5. Creating a R evolved Sur face 12.15.6. Creating P eriodic B oundar ies 12.15.1. Creating a B ounding B ox In some c ases , you ma y want to cr eate a b ox tha t encloses the input geometr y (for e xample , creating a wind tunnel ar ound the geometr y).You c an cr eate a b ounding b ox around the input geometr y or only the selec ted z ones of the geometr y using the Bounding B ox dialo g box, or the Constr uct Geo- metr y tool.You c an also sp ecify the r equir ed clear ance values of the b ounding b ox from the b ound- aries of the geometr y. There ar e two metho ds a vailable f or cr eating b ounding b ox: Using A bsolut e Values This metho d enables y ou t o cr eate the b ounding b ox by sp ecifying the minimum and maximum e xtents of the b ounding b ox in X, Y, and Z dir ections . Using Rela tive Values This metho d enables y ou t o cr eate the b ounding b ox by sp ecifying the r elative coordina te values with reference to the selec ted fac e zone . 12.15.1.1. Using the B ounding B ox Dialo g Box The pr ocedur e for cr eating a b ounding b ox is as f ollows: 1. Selec t the z ones ar ound which y ou w ant to create a b ounding b ox in the Face Zones list. 2. Selec t the appr opriate metho d in the Metho d list. a. For the Absolut e metho d, specify the b ounding b ox extents (X M in,X M ax,Y M in,Y M ax,Z M in, and Z M ax). If you click Comput e, the e xtents will b e comput ed such tha t the b ounding b ox encloses the selec ted b oundar y zones . b.For the Rela tive metho d, specify the clear ance values in the Delta entry fields ( Delta X M in,Delta X M ax,Delta Y M in,Delta Y M ax,Delta Z M in, and Delta Z M ax). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 310Manipula ting the B oundar y MeshInitially , all the Delta entry fields will b e set t o 0.This implies tha t the b ounding b ox will touch the b oundar ies of the selec ted fac e zones . Positiv e delta v alues indic ate tha t the bounding b ox will b e created outside the initial b ounding b ox while nega tive values indic ate that the b ounding b ox will b e created inside the initial b ounding b ox. 3. Specify an appr opriate value f or Edge L ength .When y ou click Comput e for the Absolut e metho d, the value will b e aut oma tically set t o 1/10th tha t of the minimum length of the b ounding b ox. 4. Enable Create Objec t if you need t o create a geometr y objec t based on the b ounding b ox fac e zone created. Note Do not use the Create O bjec t option if the b ox is t o be used as a b ody of influenc e while setting up the siz e func tions . 5. Click Draw to visualiz e the b ounding b ox. 6. Click Create to create a b ounding b ox based on the sp ecified par amet ers. 12.15.1.2. Using the C onstruc t Geometr y Tool The Constr uct Geometr y tool ( ) enables y ou t o cr eate a b ounding b ox for selec ted or all z ones displa yed in the gr aphics windo w.The b ounding b ox extents ar e comput ed based on the en tities selec ted or displa yed and ar e indic ated in the gr aphics windo w. 1. Selec t the z ones (if r equir ed) and click the Bounding B ox tool ( ) to pr eview the b ounding b ox extents.The b ounding b ox is alw ays created in the global X-Y-Z ax es. 2. The b ounding b ox extents can b e alt ered in teractively b y selec ting the dir ection and dr agging the mouse t o change the b ox dimensions . Click the y ellow dot on the b ounding b ox sur face to selec t the direction. 3. Click Create ( ) to op en the Create Objec t dialo g box. a. Enter an appr opriate Objec t Name . b.Specify the mesh siz e for the sur face mesh. By default , the edge length is c omput ed as one fif th of the smallest side . Alternatively, enable Specify S izing and sp ecify the siz e to be used . Click Preview to visualiz e the siz e set. 4. Click Create to create the b ounding b ox. A geometr y objec t compr ising the b ounding b ox fac e zones will b e created. 311Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Creating Sur faces12.15.2. Creating a P lanar S urface M esh In some c ases , you ma y need t o cr eate a plane sur face mesh in the geometr y (for e xample , creating a baffle-lik e sur face inside a hollo w tub e).You c an cr eate a plane sur face and mesh the sur face using triangular fac es of the r equir ed siz e using the Plane S urface dialo g box. Warning It is p ossible t o cr eate a planar sur face only of r ectangular shap e; you c annot cr eate a planar sur face of an y other shap e. There ar e two metho ds a vailable f or cr eating planar sur face mesh: •Axis D irection M etho d: This metho d enables y ou t o cr eate the plane sur face perpendicular t o an y of the c oordina te ax es. Selec t the axis p erpendicular t o which y ou w ant to cr eate a planar sur face mesh and then, specify the c oordina tes of the p oints tha t will f orm a r ectangular sur face perpendicular t o the axis selec ted. You c an also cr eate a plane sur face enclosing the b oundar ies of the selec ted fac e zone using this metho d. •Planar P oints M etho d: This metho d enables y ou t o cr eate a plane sur face mesh fr om thr ee p oints in the geometr y selec ted using the mouse . The c oncept of the planar p oints metho d is sho wn in Figur e 12.22: Planar P oints M etho d (p.312). After sp ecifying the planar p oints, the first p oint (P1) and sec ond p oint (P2) are connec ted t o each other b y a line ( line-1 ). Another line ( line-2 ) is dr awn thr ough the thir d point (P3) par allel t o the first line . Perpendiculars ar e dr awn fr om p oints P1 and P3 on line-2 and line-1 respectively. Figur e 12.22: Planar P oints M etho d Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 312Manipula ting the B oundar y MeshThis cr eates a r ectangular sur face tha t you c an mesh as r equir ed. 12.15.2.1. Using the P lane S urface Dialo g Box The pr ocedur e for cr eating a sur face mesh is as f ollows: 1. Selec t the appr opriate metho d in the Options list. a. For the Axis D irection metho d, selec t the appr opriate fac e zones , direction, and sp ecify the c o- ordina tes of the p oints perpendicular t o the axis . If you selec t X A xis then the en try box for sp ecifying c oordina tes in X dir ection will not b e accessible .This applies t o the other t wo ax es as w ell. b.For the Points metho d, specify the c oordina tes for the thr ee p oints defining the plane .You c an click the Selec t Points... butt on and selec t the p oints using the mouse butt on. 2. Specify an appr opriate value f or Edge L ength . If you click Comput e, the Edge L ength will b e comput ed as 1/10th of the minimum distanc e along the c oordina te ax es. 3. Enable Create Objec t if you need t o create a geometr y objec t based on the plane sur face fac e zone created. 4. Click Draw to visualiz e the sur face. 5. Click Create to create the planar sur face. 12.15.3. Creating a C ylinder/F rustum In some c ases , you ma y want to cr eate a c ylinder or fr ustum within the e xisting geometr y (for e xample , creating an MRF z one f or pr oblems in volving mo ving par ts such as r otating blades or imp ellers , creating a cylindr ical sur face to close a gap in the geometr y, and so on). You c an cr eate a c ylindr ical sur face and mesh it with a tr iangular sur face mesh using the options a vailable in the Cylinder dialo g box, or the Constr uct Geometr y tool. •Using 3 A rc Nodes: You c an cr eate a c ylindr ical sur face using thr ee no des tha t lie on a cir cular ar c (see Figur e 12.23: Cylinder D efined b y 3 A rc Nodes, Radial G ap, and A xial D elta (p.314)). Specify the r adial gap and tap er angle tha t will det ermine the ac tual r adii of the c ylinder/fr ustum t o be created.You c an sp ecify a positiv e or nega tive radial gap v alue dep ending on the r equir ed siz e of the c ylinder/fr ustum. A tap er angle of z ero will r esult in a c ylinder .The axial delta v alues det ermine the axial length of the c ylinder/fr ustum. The Caps option enables y ou t o create the cir cular c apping sur faces along with the c ylindr ical sur face. 313Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Creating Sur facesFigur e 12.23: Cylinder D efined b y 3 A rc Nodes , Radial G ap, and A xial D elta •Using 3 A rc Nodes and a H eigh t Node: You c an cr eate a c ylindr ical sur face using thr ee no des which lie on a cir cular ar c, and a f ourth no de t o det ermine the heigh t of the c ylinder/fr ustum (see Figur e 12.24: Cyl- inder D efined b y 3 A rc Nodes and a H eigh t Node (p.315)).The r adii, heigh t, and tap er angle will b e det erm- ined based on the no des selec ted. Note A planar annular sur face will b e created if the f our no des selec ted ar e in the same plane (tha t is, the heigh t is z ero). The Caps option enables y ou t o create the cir cular c apping sur faces along with the c ylindr ical sur face. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 314Manipula ting the B oundar y MeshFigur e 12.24: Cylinder D efined b y 3 A rc Nodes and a H eigh t Node •Using 2 A xis L ocations or 2 A xis N odes: You c an also cr eate a c ylindr ical sur face by sp ecifying the r adii (r1, r2) of the c ylinder/fr ustum and t wo points (P1 and P2) defining the axis (see Figur e 12.25: Cylinder Defined b y Axial P oints and R adii (p.316)). Equal v alues of r1 and r2 will r esult in a c ylinder .The axis c an b e defined b y sp ecifying the lo cation (X, Y, Z) of the p oints or b y sp ecifying the appr opriate boundar y no des corresponding t o the axial p oints P1 and P2. The Caps option enables y ou t o create the cir cular c apping surfaces along with the c ylindr ical sur face. 315Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Creating Sur facesFigur e 12.25: Cylinder D efined b y Axial P oints and R adii 12.15.3.1. Using the C ylinder D ialo g Box The pr ocedur e for cr eating a c ylindr ical sur face is as f ollows: 1. Selec t the appr opriate option f or defining the c ylinder . a. For the 3 Arc Nodes metho d, selec t the no des on the cir cular ar c. Enter appr opriate values f or Axial D elta 1 ,Axial D elta 2 ,Taper A ngle , and Radial G ap. b.For the 3 Arc, 1 H eigh t Node metho d, selec t the 3 no des on the cir cular ar c and the heigh t no de. c.For the 2 Axis L ocations and 2 Axis N odes metho ds, specify the p oints defining the axis .You c an specify the lo cations (or no de IDs) manually . Alternatively, you c an click the Selec t Points... (or the Selec t Nodes ...) butt on and selec t the p oints using the mouse . Enter appr opriate values f or Radius1 and Radius2 . 2. Enter an appr opriate value f or Edge L ength . 3. Enable Caps to create the cir cular c apping sur faces along with the c ylindr ical sur face. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 316Manipula ting the B oundar y Mesh4. Enable Create Objec t if you need t o create a geometr y objec t based on the c ylinder/fr ustum fac e zones created. Note Do not use the Create O bjec t option if the c ylinder/fr ustum is t o be used as a b ody of influenc e while setting up the siz e func tions . 5. Click Preview to pr eview the c ylinder t o be created. 6. When y ou ar e sa tisfied with the settings , click Create to create the c ylindr ical sur face. Enter an appr o- priate zone name pr efix in the Objec t/Zone P refix dialo g box and click OK. 12.15.3.2. Using the C onstruc t Geometr y Tool The Constr uct Geometr y tool ( ) enables y ou t o cr eate a c ylinder/fr ustum based on selec tions in the gr aphics windo w.The c ylinder/fr ustum dimensions ar e comput ed based on the en tities selec ted or displa yed and ar e indic ated in the gr aphics windo w. 1. Selec t the en tities and click the Cylinder tool ( ) to pr eview the c ylinder e xtents. Alternatively, click the Frustum tool ( ) to pr eview the fr ustum e xtents. •When no selec tions ar e made , the c ylinder/fr ustum is aligned along the global Z-axis .The default heigh t and r adius ar e comput ed based on the b ounding b ox dimensions f or the en tities displa yed. •When fac e zones ar e selec ted, the c ylinder/fr ustum is aligned along the global Z- axis . If any two di- mensions of the b ounding b ox for the selec ted z ones ar e the same , the c ylinder/fr ustum will b e aligned along the thir d (remaining) dir ection. The default heigh t and r adius ar e comput ed based on the b ounding b ox dimensions f or the z ones selec ted. •When a single no de is selec ted, it is used as an axis no de.The c ylinder/fr ustum will b e aligned along the global Z- axis .The default r adius and heigh t are equal and c omput ed as one-t enth the length of the diagonal of the b ounding b ox for the displa yed z ones . If no z ones ar e displa yed, a value one- tenth the length of the diagonal of the global b ounding b ox will b e used . •When t wo no des ar e selec ted, the mid-p oint of the line joining the t wo is used as an axis no de and the c ylinder/fr ustum will b e aligned along the global Z-axis . If the no des selec ted ar e aligned in the Z-axis , the c ylinder/fr ustum will b e aligned along the global Y-axis inst ead.The default r adius and heigh t are equal, and c omput ed as half the distanc e between the selec ted no des. •When thr ee no des ar e selec ted, the c ylinder/fr ustum base cir cle passes thr ough the selec ted no des. The axial dir ection is det ermined b y the r ight hand thumb r ule.The default r adius and heigh t are equal. The r adius is det ermined b y the no des selec ted. •When f our no des ar e selec ted, the first thr ee ar e used t o det ermine the c ylinder/fr ustum base cir cle. The fourth no de is used t o det ermine the heigh t.The r adius is det ermined b y the first thr ee no des selec ted. 317Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Creating Sur faces2. The c ylinder dimensions c an b e alt ered in teractively b y selec ting the dir ection and dr agging the mouse to change the dimensions . Click the y ellow dot on the c ylinder sur face to change the heigh t. The fr ustum dimensions c an b e alt ered in teractively b y selec ting the dir ection and dr agging the mouse t o change the dimensions . Click the y ellow dot on either sur face to change the r adii and heigh t. 3. Click Create ( ) to op en the Create Objec t dialo g box. a. Enter an appr opriate Objec t Name . b.Specify the mesh siz e for the sur face mesh. By default , the edge length is c omput ed as one-se venth the a verage r adius or heigh t, whiche ver is smaller . Alternatively, enable Specify S izing and sp ecify the siz e to be used . Click Preview to visualiz e the siz e set. c.The Caps option enables y ou t o create the cir cular c apping sur faces along with the c ylindr ical surface. Disable this option t o obtain only the c ylindr ical sur face. 4. Click Create to create the c ylinder/fr ustum. A geometr y objec t compr ising the c ylinder/fr ustum fac e zones will b e created. 12.15.4. Creating a S wept S urface In some c ases , you ma y want to cr eate a sw ept sur face by pr ojec ting an edge z one along a sp ecified linear distanc e in a sp ecified dir ection. You c an cr eate a sw ept sur face using the options a vailable in the Swept S urface dialo g box. 12.15.4.1. Using the S wept S urface Dialo g Box The pr ocedur e for cr eating a sw ept sur face is as f ollows: 1. Create the edge z one f or the sw ept sur face. •Use the in teractive edge z one cr eation t ool to extract edge z ones fr om e xisting fac e zones or sur faces. See Extract Edge Z ones (p.327) for details . •Use the L oop S elec tion t ool to create an edge z one fr om selec ted no des or p oints. See Using the Loop S elec tion Tool (p.323) for details . •Use edge z one cr eation and mo dific ation options a vailable in the Manage O bjec ts,Feature M odify , or Surface Retr iangular ization dialo g boxes. See Objec t Manipula tion Op erations (p.233),Using the Feature Modify D ialog Box (p.296), or Using the Sur face Retriangula tion D ialog Box (p.300) respectively. 2. Open the Swept S urface dialo g box. Boundar y → Create → Swept S urface... 3. Selec t the edge z one t o be sw ept fr om the Edge Z ones drop-do wn list. 4. Selec t the c orresponding fac es fr om the Face Zones selec tion list. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 318Manipula ting the B oundar y Mesh5. Specify the distanc e along which the edge is t o be sw ept in the Total D istanc e field . 6. Specify the appr opriate value in the No. of O ffsets field . 7. Specify the Vector defining the dir ection in which the edge is t o be sw ept. Alternatively, you c an click Define and selec t two no des or p ositions t o sp ecify the v ector.The Total D istanc e is also c omput ed based on the no des/p ositions selec ted. 8. Enable Split Q uad F aces, if requir ed. 9. Enable Create Objec t if you need t o create a geometr y objec t based on the sw ept sur face fac e zone created. 10. Click Create to create the sw ept sur face. 12.15.5. Creating a Re volved S urface In some c ases , you ma y want to cr eate a r evolved sur face from sp ecific edge z ones .The r evolved sur face is cr eated b y revolving the selec ted edge z ones thr ough the angle sp ecified using the piv ot and axis of rotation defined .You c an cr eate a r evolved sur face using the options a vailable in the Revolved Surface dialo g box. 12.15.5.1. Using the R evolved S urface Dialo g Box The pr ocedur e for cr eating a r evolved sur face is as f ollows: 1. Create the edge z ones t o be used f or cr eating the r evolved sur face. •Use the in teractive edge z one cr eation t ool to extract edge z ones fr om e xisting fac e zones or sur faces. See Extract Edge Z ones (p.327) for details . •Use the L oop S elec tion t ool to create an edge z one fr om selec ted no des or p oints. See Using the Loop S elec tion Tool (p.323) for details . •Use edge z one cr eation and mo dific ation options a vailable in the Manage O bjec ts,Feature M odify , or Surface Retr iangular ization dialo g boxes. See Objec t Manipula tion Op erations (p.233),Using the Feature Modify D ialog Box (p.296), or Using the Sur face Retriangula tion D ialog Box (p.300) respectively. 2. Open the Revolved S urface dialo g box. Boundar y → Create → Revolved S urface... 3. Selec t the edges t o be revolved fr om the Edge Z ones selec tion list. 4. Specify the appr opriate value in the Numb er of S egmen ts field . 5. Specify the angle thr ough which the edge is t o be revolved in the Angle field . 6. Specify an appr opriate value f or Scale F actor dep ending on the r adius r equir ed f or the r evolved sur face. 7. Specify the piv ot p oint and the axis of r evolution. Click Define and selec t 1-6 no des t o define the piv ot and axis as f ollows: 319Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Creating Sur faces•If only 1 no de is selec ted, the piv ot p oint is a t the no de lo cation and the axis of r otation is the global z-axis . •For 2 no des, the piv ot p oint is a t the midp oint of the no des selec ted and the axis of r otation is the global z-axis . •For 3 no des, the piv ot p oint is a t the first no de selec ted.The axis of r otation is the lo cal z-axis nor mal to the plane defined b y the thr ee p oints, the p ositiv e dir ection is det ermined b y the r ight-hand r ule. •For 4, 5 or 6 no des, the first 3 p oints define a cir cle.The piv ot p oint is a t the c enter of the cir cle.The axis of r otation is the lo cal z-axis nor mal t o the cir cular plane , the p ositiv e dir ection is det ermined b y the r ight-hand r ule. 8. Enable Create Objec t if you need t o create a geometr y objec t based on the r evolved sur face fac e zone created. 9. Click Create to create the r evolved sur face. 12.15.6. Creating P eriodic B oundar ies Use the Make Periodic B oundar ies dialo g box to Create or Rec over the p eriodic r elationship b etween mast er and shado w fac e zones in a single mesh objec t.The p eriodic b oundar ies ar e iden tical and contain either fac e or no de c orrespondenc e inf ormation. The Make Periodic B oundar ies dialo g box is acc essible using the c ontext sensitiv e menu under an y mesh objec t or using the Boundar y → Create → Periodic... menu . Creat e Perio dic B oundaries You c an Create new p eriodic b oundar ies using the f ollowing pr ocedur e. 1. In the pr eprocessor , create only one of the b oundar ies which is t o be made p eriodic.The t o-be-periodic boundar y ma y ha ve multiple fac e zones , but should b e an y non-p eriodic b oundar y type. 2. In the Make Periodic B oundar ies dialo g box in F luen t meshing , selec t the b oundar y zone(s) fr om the Boundar y Zones list. You c an also selec t the z one(s) gr aphic ally; the names will b e highligh ted in the Boundar y Zones list. 3. Enter, or check f or accur acy, the p eriodicit y inf ormation (angle , pivot and axis f or rotational p eriodicit y; shift vector for tr ansla tional p eriodicit y) in the Make Periodic B oundar ies dialo g box. Periodicit y inf ormation ma y be defined gr aphic ally (see b elow) or using the c ontext-sensitiv e menu under Model in the Outline View, or r ead in with the mesh file . 4. Click Create. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 320Manipula ting the B oundar y MeshA corresponding p eriodic shado w b oundar y will b e added t o the objec t. A z one t ype of p eriodic will b e assigned t o both the p eriodic and the p eriodic-shado w zones , and the fac e/no de c orres- pondenc e will b e gener ated. Imp ortant •This is the only w ay to create periodic b oundar ies in the meshing mo de; it is not sufficien t to simply set a z one t ype to be periodic. •Periodicit y inf ormation will b e stored with the mesh da ta and will b e extracted when the mesh file is r ead. Multiple p eriodicities ma y be created, but only the first is r ead aut oma tically with the mesh da ta. To define p eriodicit y inf ormation b y other means , follow these st eps. •For rotational p eriodicit y, the piv ot p oint and axis of r otation c an b e defined gr aphic ally b y selec ting 1-6 nodes as f ollows, and then click ing Define . –If only 1 no de is selec ted, the piv ot p oint is a t the no de lo cation and the axis of r otation is the global z- axis. –For 2 no des, the piv ot p oint is a t the midp oint of the no des selec ted and the axis of r otation is the global z-axis . –For 3 no des, the piv ot p oint is a t the first no de selec ted.The axis of r otation is the lo cal z-axis nor mal t o the plane defined b y the thr ee p oints, the p ositiv e dir ection is det ermined b y the r ight-hand r ule. –For 4, 5 or 6 no des, the first 3 p oints define a cir cle.The piv ot p oint is a t the c enter of the cir cle.The axis of rotation is the lo cal z-axis nor mal t o the cir cular plane .The x-axis (0°) is defined b y the 4th, 5th and 6th p oints and the p ositiv e dir ection is det ermined b y the r ight-hand r ule. •For tr ansla tional p eriodicit y, the shif t vector can b e defined gr aphic ally click ing Define and then selec ting two no des. •Rotational p eriodicit y inf ormation ma y be set using the Periodicit y dialo g box acc essed b y right click ing on Model in the Outline View. •Rotational p eriodicit y inf ormation ma y be set using the t ext command boundary/set-periodicity . When the p eriodic-shado w b oundar y is cr eated fr om the or iginal (p eriodic) b oundar y, the no des ar ound the out er edges of the shado w zone will b e duplic ates of e xisting no des.These duplic ates will b e mar ked as fr ee, so the y can b e verified b y coun ting them and dr awing them. Before gener ating the initial mesh, you must mer ge these no des. Imp ortant To ensur e tha t the p eriodic-shado w b oundar y creation w orks pr operly, you must define the node distr ibution c orrectly in the pr eprocessor tha t gener ates the b oundar y mesh. 321Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Creating Sur facesEnsur e tha t the distr ibution of no des on the b oundar ies tha t will b e shar ed b y the shado w zone and the sur faces adjac ent to it is the same as the distr ibution on the b oundar ies shar ed b y the or iginal (periodic) z one and its adjac ent sur faces. Note Files cr eated pr ior t o Release 15 wr itten in mesher mo de ar e aut oma tically c onverted when read in to mesher mo de.These files ma y not c ontain sufficien t inf ormation t o pr operly set up p eriodic inf ormation in c ase of multiple p eriodic pairs . Recover P erio dic B oundaries You c an Rec over periodic b oundar ies if it e xists fr om a mesh file using the f ollowing pr ocedur e. 1. Read the mesh file . 2. In the Make Periodic B oundar ies dialo g box in F luen t meshing , selec t the p eriodic b oundar y zone(s) from the B oundar y Zones list. Tip You c an also selec t the z one(s) gr aphic ally, and the names will b e highligh ted in the Boundar y Zones list. 3. If it e xists , periodic inf ormation (angle , pivot, and or igin) will b e extracted fr om the mesh file when it is r ead and will app ear in the Periodicit y dialo g box. Alternatively, you c an manually en ter periodic inf ormation as descr ibed ab ove. 4. Click Rec over. The R ecover feature will check f or an y existing fac e zone(s) a t the p eriodic shado w b oundar y. If a shado w fac e zone is mor e comple x than the c orresponding mast er, the r ecover op eration will fail f or tha t zone and a w arning will app ear in the c onsole .You ma y be able t o recover the p eri- odic b oundar y by reversing the angle and selec ting the mor e comple x fac e zone(s). Note •Recover first cr eates the p eriodic shado w boundar y and then r emo ves an y duplic ate fac e zone(s) at the p eriodic shado w boundar y. •Periodic b oundar y recovery ma y be initia ted using the t ext command boundary/recover- periodic-surfaces . 12.16. Remo ving G aps B etween B oundar y Zones Use the Remo ve Boundar y Gaps dialo g box to remo ve gaps b etween b oundar y zones . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 322Manipula ting the B oundar y Mesh1. Selec t the tar get z one in the gr aphics windo w. Click to set the tar get z one . 2. Selec t the z ones f or the gap r emo val op eration and click to op en the Remo ve Boundar y Gaps dialo g box. Alternatively, selec t the z ones and use the hot-k ey Ctrl+K. 3. Specify an appr opriate value f or the Min. Gap D istanc e,Max. Gap D istanc e, and Percentage M argin. 4. Specify an appr opriate value f or Critical A ngle .The cr itical angle is the maximum angle b etween the faces c onstituting the gap t o be remo ved. 5. Click Mark to see the fac es mar ked f or pr ojec tion. 6. Click Remo ve to remo ve the gaps b etween the objec ts selec ted. 12.17. Using the L oop S elec tion Tool The lo op selec tion t ool can b e acc essed b y click ing in the gr aphics windo w or using the hot-k ey Ctrl+Shift+L.This t ool pr ovides options f or cr eating an op en or closed lo op of no des.You c an cr eate an edge z one or c apping sur face based on the lo op selec ted.You c an also selec t positions inst ead of nodes t o define the lo op. Figur e 12.26: Loop S elec tion Toolbar The f ollowing selec tion options ar e available: •In the first gr oup of t ools, cho ose ho w the pa th b etween selec ted no des/p ositions is defined - b y edges , feature, boundar y, or dir ect pa th. Click to swit ch b etween selec ting no des or p ositions t o define the loop. •The sec ond gr oup of ic ons is used t o selec t op en or closed lo op.Then, for closed lo op mo de, you c an cho ose how the pa th b etween the first and last no des is defined - b y edges , feature, boundar y, or dir ect pa th. Creating a C apping S urface After mak ing the nec essar y selec tions , click (hot-k ey Ctrl+K) in the L oop S elec tion mo de t o op en the Create Cap dialo g box.The Create Cap dialo g box contains options f or objec t/zone gr anular ity and t ype and f or remeshing the c apping sur face. 1. Specify the objec t/zone gr anular ity. •Selec t New O bjec t to create a new objec t for the fac e zones . Specify the objec t name and a lab el name . If the lab el name is not sp ecified , the objec t name will b e used as the lab el name . Face zone names will be the same as the lab el names . Selec t the Objec t Type and Zone Type from the lists . 323Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the L oop S elec tion Tool•Selec t Add t o O bjec t to add the fac e zones t o an e xisting objec t. Selec t the objec t and sp ecify a lab el name . If the lab el name is not sp ecified , the default name patch:# (# indic ates the ID) will b e used . Face zone names will b e the same as the lab el names . Selec t the Zone Type from the list. •Selec t Add t o Unreferenc ed to create unr eferenced fac e zones . Selec t the Zone Type from the list. The default name patch:# (# indic ates the ID) will b e used f or the z one name .These z ones will b e available in the Unreferenc ed branch of the tr ee. 2. Enable Remesh to remesh the c apping sur face created. 3. Click Create in the Create Cap dialo g box. Creating an E dge Z one After mak ing the nec essar y selec tions , click (hot-k ey Ctrl+L) in the L oop S elec tion mo de t o op en the Create Edge Z ones dialo g box.The Create Edge Z ones dialo g box enables y ou t o add the edge zone t o an e xisting objec t or cr eate an unr eferenced edge z one . Selec ting all N odes After mak ing the nec essar y selec tions , click (hot-k ey Ctrl+J) in the L oop S elec tion mo de t o selec t all the no des on the lo op.These selec tions c an then b e used f or op erations such as c ollapsing , mer ging , or smo othing no des. For the list of hot-k eys asso ciated with the options in the L oop S elec tion t oolbar , refer to Ap- pendix C: Shortcut Ke ys (p.527). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 324Manipula ting the B oundar y MeshChapt er 13: Wrapping O bjec ts Geometr ies migr ated fr om v arious C AD pack ages of ten c ontain gaps and o verlaps b etween the sur faces due t o algor ithm and t oler ance diff erences of the C AD pack ages . Repair ing such geometr ies manually is a t edious and time-c onsuming pr ocess.Wrapping pr ovides the abilit y to cr eate reliable meshes f or such geometr ies without e xtensiv e manual clean up and r educ es the time r equir ed f or pr eprocessing . The objec t wr apping op eration: •extracts a c onformal, well c onnec ted mesh objec t on the r elevant sur faces of the objec ts selec ted. •can r epair gaps and o verlaps in the mo del a t the e xpense of a user-sp ecified degr ee of geometr y details . •can handle unclean geometr ies and do es not r equir e a w atertigh t represen tation of the geometr y. •can b e used f or def eaturing or when y ou need t o walk o ver features. The wr app er is useful in the f ollowing industr ial applic ations: •Automotiv e –Under hood ther mal managemen t (engine only , front car, full c ar) –Cabin HV AC –External aer odynamics –Brake cooling and engine c ooling •Aerospac e –Engine c ore compar tmen t –Cockpit HV AC, cabin HV AC –Landing gear •Drill bit applic ations •Smok e and fir e spr ead •Biomedic al applic ations •Other applic ations with bad input geometr ies 13.1. The Wrapping P rocess The wr apping op eration uses an appr opriate ma terial p oint to iden tify the r elevant sur faces of the se- lected objec ts. A w ell-c onnec ted mesh objec t is cr eated. 325Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.The gener al pr ocedur e for cr eating a wr app er sur face is as f ollows: 1.A coarse C artesian gr id is o verlaid on the selec ted objec ts (including gaps and o verlaps) t o create a c on- tiguous r egion. This C artesian gr id is used t o aut oma tically clean the input geometr y and t o create the water-tigh t represen tation. 2.The C artesian gr id is then r efined based on the siz e func tions t o better represen t the selec ted objec ts. 3.The in tersec tion b etween the C artesian gr id and the input geometr y is c alcula ted and the in tersec ting c ells are iden tified and mar ked. 4.The in terface is e xtracted on the b oundar y of the non-in tersec ting C artesian v olume r egion tha t encloses the ma terial p oint. A w atertigh t, faceted r epresen tation is cr eated along the b oundar y of the in tersec ting cells. 5.The no des on this fac eted r epresen tation ar e pr ojec ted on to the fac es and f eature edges of the input geometr y which then r esults in a wr app er sur face closely r epresen ting the input geometr y.The edges ar e impr inted on the wr app ed z ones , and individual z ones ar e recovered and r ezoned based on the or iginal geometr y objec t(s). 6.The wr app er sur face qualit y is impr oved b y post-wr apping op erations such as smo othing , swapping , and so on. Degener ate and island edges ar e delet ed, and in tersec ted and r emeshed as appr opriate. Sur faces are remeshed based on siz e func tions/siz e field . Figur e 13.1: Schema tic R epresen tation of Wrapping P rocess (p.326) is a simple illustr ation of these st eps. Figur e 13.1: Schema tic Repr esen tation of Wrapping P rocess Note •If the global minimum siz e sp ecified c annot b e resolv ed, an er ror will b e reported. Set up appr o- priate siz es and c omput e the siz e field b efore wr apping . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 326Wrapping O bjec tsIf the minimum and maximum siz es fr om the siz e field c annot b e resolv ed, incr ease the minimum siz e and r ecomput e the siz e field b efore wr apping . •The wr apping op eration appr oxima tes the geometr y using a stairst ep-lik e Cartesian gr id without projec tion. It requir es finer c ells t o resolv e thin gaps . In cases when a gap ar ea is cur ved and not aligned t o the C artesian ax es, you ma y need to refine 3–4 times finer than the gap thick ness .This should b e tak en in to acc oun t while setting the global and lo cal minimum siz e for siz e func tions and the c ells p er gap f or the proximit y siz e func tion b eing used . You ma y sp ecify a Resolution F actor to allo w finer c ells without changing the siz e func tion. •The dimensions of the dist ortion (f or e xample hole , gap , and so on) in the input geometr y should be smaller than tha t of the siz e of the C artesian c ells cr eated b y the wr app er. If ther e is signific ant distortion in the input geometr y, repair it t o the e xtent tha t the dist ortion b ecomes smaller in size. Large holes , if pr esen t in the initial geometr y, should b e filled . Other wise such holes will b e ignor ed in the wr apping pr ocess. The objec t wr apping utilit y is acc essed using the c ontext sensitiv e menus . Right click on an y objec t and selec t Wrap.The f ollowing sec tions discuss t ools and options used in the wr apping pr ocess. Note The Impr ove... option is a vailable only f or mesh objec ts. 13.1.1. Extract Edge Z ones 13.1.2. Create Intersec tion L oops 13.1.3. Setting G eometr y Recovery Options 13.1.4. Fixing H oles in O bjec ts 13.1.5. Shrink Wrapping the O bjec ts 13.1.6. Impr oving the M esh O bjec ts 13.1.7. Objec t Wrapping Options 13.1.1. Extract Edge Z ones You c an easily e xtract edge z ones fr om e xisting fac e zones or selec ted sur faces using c ontext menus from the tr ee or onscr een t ools. In either c ase, edge z ones ar e created using the Fixed A ngle criterion as descr ibed in Creating E dge Z ones (p.292) 327Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.The Wrapping P rocessUsing O nscr een Tools You c an use the onscr een t ools t o cr eate edge z ones in teractively on selec ted fac e zones or selec ted surfaces.This metho d has the ad vantage of pr eviewing an y edges tha t meet the sp ecified cr iteria b efore creating the edge z ones . 1.Set the r equir ed S elec tion F ilter. •Use Face Selec tion F ilter to create edge z ones on the sur face(s) tha t contain the selec ted fac e(s). •Use Zone S elec tion F ilter to create edge z ones on the selec ted fac e zone(s). 2.Using the mouse pr obe, selec t the fac e(s) or fac e zone(s) f or which edge z ones ar e to be created. 3.Click the Create Edge Z ones tool butt on ( ). •If a z one is selec ted, the Interactive Edge Z one C reation dialo g box op ens. •If a fac e is selec ted, the Create Edge Z ones B y seed dialo g box op ens. Any edges on the selec ted sur face, or fac e zone , tha t meet the dihedr al angle cr iterion will b e highligh ted. 4.Adjust the Preview E dge A ngle slider as nec essar y to selec t the edge thr eads t o be included in the new edge z one , based on the Fixed A ngle criterion. 5.Click Create Edge Z ones . The new edge z one will b e added t o the objec t tha t contains the selec ted fac e (or fac e zone). Using C ont ext Menus You c an use the c ontext menus t o extract edge z ones f or an y selec ted geometr y or mesh objec t in the tr ee. 1.In the Outline View, selec t the geometr y objec t or mesh objec t. 2.Right-click on the selec ted objec t, and selec t Wrap → Extract Edges .... Note This option is also a vailable under the Advanc ed menu . 3.Specify the thr eshold Angle . From the Option list, cho ose whether feature or all edges ar e to be extracted. 4.Click OK. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 328Wrapping O bjec tsThe e xtracted edge z ones ar e plac ed in the Unreferenc ed branch of the tr ee. Note •The Extract Edges dialo g box off ers the same func tionalit y as the Edge Z ones group on the Operations tab of the Manage O bjec ts dialo g box. See Objec t Manipula tion Op erations (p.233). •The Feature M odify and Surface Retr iangular ization dialo g boxes also c ontain gr oups t o modify or cr eate Edge Z ones . See Creating and M odifying F eatures (p.291) or Remeshing Boundar y Zones (p.298). 13.1.2. Create In tersec tion L oops You c an use these options t o cho ose ho w fac e zones ar e pr ocessed within objec ts, prior t o wr apping . 13.1.2.1. Individuall y Within each objec t, edge z ones ar e created on the lo ops wher e the fac e zones o verlap. In Figur e 13.2: In- dividual O bjec t Loop (p.329), after applying Create In tersec tion L oops → Individually to all objec ts, only one such edge z one is cr eated - in the lar ge geometr y objec t at the in tersec tion of the t wo cubic volumes . Figur e 13.2: Individual O bjec t Loop 13.1.2.2. Collec tively Edge z ones ar e created on the lo ops wher e fac e zones o verlap, both within a single objec t and between multiple objec ts. In Figur e 13.3: Collec tive Objec t Loops (p.330), an additional edge z one is created wher e the lar ge geometr y objec t intersec ts the smaller objec t. 329Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.The Wrapping P rocessFigur e 13.3: Collec tive O bjec t Loops 13.1.3. Setting G eometr y Rec overy Options You c an det ermine the sur faces and f eatures which need t o be captur ed with higher accur acy based on the usage of the mo del. For e xample , when using a c ar mo del f or an e xternal aer odynamic simula tion, the r ecovery of e xternal sur faces requir es gr eater accur acy. Other c omp onen ts lik e the br aking sy stem or under hood comp onen ts can b e recovered with lo wer accur acy sinc e the y are not as signific ant for the simula tion. The r ecovery of f eatures and sur face mesh qualit y are controlled b y setting the Geometr y Rec overy attribut e for objec ts or fac e zones in the Geometr y Rec overy Options dialo g box.The wr app ed sur face mesh inher its the geometr y recovery attribut e from the under lying objec ts or fac e zones . Low enables y ou t o create a r ough wr app ed r epresen tation of the selec ted objec ts. Features ar e not pr eser ved and the mesh qualit y is not as go od as a CFD mesh. High enables b etter feature captur e and high qualit y sur face mesh. By default , the High attribut e is set f or all face zones in the mesh. To set the geometr y recovery attribut e, 1.Right-click on an y geometr y or mesh objec t, and then selec t Wrap → Geometr y Rec overy Options ... to op en the Geometr y Rec overy Options dialo g box. 2.Selec t the objec ts or fac e zones in the selec tion list. 3.Click Apply for the appr opriate option in the Geometr y Rec overy group b ox. To visualiz e the geometr y recovery option, use the hot k ey Ctrl+Shift+C to go t o Color Options M ode, then Ctrl+G to apply c olor b y geometr y recovery. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 330Wrapping O bjec ts13.1.4. Fixing H oles in O bjec ts The r egion/v olume of in terest should b e well c onnec ted b efore the v olume mesh c an b e gener ated. Any holes or leaks need t o be lo cated and fix ed b efore pr oceeding with v olume meshing . Holes/leaks can b e lo cated using a ma terial p oint.When y ou selec t the ma terial p oint and set the minimum and maximum limits f or the hole siz e, those lo cations , within the set siz e limits , at which a pa th tr aces back to the ma terial p oint thr ough the geometr y are recogniz ed as holes or leaks . When y ou r efine an e xisting r egion or sp ecify additional sizing func tions f or b etter represen tation of the geometr y, the minimum siz e ma y be reduc ed t o a siz e smaller than some e xisting leak ages .These leak ages c an b e det ected aut oma tically using the aut oma tic hole det ection t ool in ANSY S Fluen t Meshing .The r efinemen t of a r egion ma y result in the joining of pr eviously separ ate regions thr ough cells newly in troduced b y the r efinemen t (region c ollision). While r efining a r egion, ANSY S Fluen t Meshing will aut oma tically det ect cells c ausing r egion c ollision and gr oup them. Such gr oups of c ells will b e iden tified as holes in the r egion. The numb er of holes e xposed b y the cur rent refinemen t will be reported in the c onsole . The f ollowing op erations allo w you t o aut oma tically det ect holes: •Refining a single r egion. •Specifying lo cal siz e func tion and additional z one-sp ecific siz es af ter initializa tion. •Refining lo cal regions defined acc ording t o requir emen ts.   You c an use the Fix H oles dialo g box to lo cate and fix such holes as descr ibed in the f ollowing gener ic procedur e: 1. Right-click on the selec ted geometr y or mesh objec t(s) in the M odel tr ee and then selec t Wrap → Fix Holes .... You c an add or change Objec ts using the selec tion list in the dialo g box. Click Draw to displa y only the selec ted objec t(s) in the gr aphics windo w. 2. Selec t an appr opriate ma terial p oint. The default ma terial p oint (external) is a suitable p oint, external t o the selec ted objec ts. Click Change to enable the Material P oint drop-do wn list , if nec essar y. 3. Retain the Use S ize Field option, if requir ed. This will use a siz e field based on pr eviously defined siz e controls or siz e func tions t o det ermine the limits f or hole siz es. a. Set a Resolution F actor if desir ed. Setting a v alue less than 1 c an help t o find holes not aligned t o the C artesian ax es b y using finer sampling than the giv en siz e field . In situa tions wher e a hole's minimum siz e is lar ger than the siz e field's minimum siz e, using a Resolution F actor helps t o find holes without mo difying the siz e field .That is, you c an use the same siz e field f or b oth hole fixing and wr apping . 331Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.The Wrapping P rocessb.Set the minimum and maximum limits f or the Hole S izes under c onsider ation. The siz e values enable y ou t o limit the sear ch f or holes t o a r elevant subset based on the size range . As you lo cate the r espective holes and fix them, the p ossibilit y of false holes is reduc ed. You c an click Draw S izes to check the siz es on the geometr y; click Draw to tur n off siz e displa y. In situa tions wher e a hole's minimum siz e is lar ger than the siz e field's minimum siz e, using the Resolution F actor helps t o find holes without mo difying the siz e field .That is, you c an use the same siz e field f or b oth hole fixing and wr apping . You c an alt ernatively cho ose t o use a sp ecific siz e to find the holes or leaks in the mesh. To find holes based on a sp ecified siz e, disable Use S ize Field . Enter an appr opriate value f or Min Size and click Apply . The Max S ize can b e set t o limit the sear ch t o a r elevant siz e range . 4. Click Find H oles to locate all the holes based on the sp ecified par amet ers. The numb er of holes is r eported in the Coun t field in the Wetted H oles group b ox. Using the P an R egions D ialo g Box The options in the Pan Regions dialo g box enable y ou t o obser ve and analyz e the r egion t o be wrapp ed, overlayed on a plane aligned with the C artesian gr id.The plane c an b e passed thr ough the selec ted r egion (or all a vailable r egions) along the X, Y, or Z dir ection, as r equir ed.The in terior of the selec ted r egion(s) is displa yed on the plane , at every position of the plane . Click Pan Regions ... to open the Pan Regions dialo g box. You c an also o verlay the b oundar y sur faces while panning , and clip the b oundar y sur faces on either side of the cutting plane . To pan thr ough all the r egions of y our choic e, do the f ollowing: 1. Displa y the r equir ed r egion (using the Draw butt on b elow the Regions list). 2. Click the Pan Regions ... butt on t o op en the Pan Regions dialo g box. 3. Selec t the appr opriate axis along which y ou w ant to pan thr ough the selec ted r egions fr om the Direction list. The Start,End, and Incr emen t fields will b e up dated aut oma tically based on the c ell siz e distr i- bution of the C artesian gr id.You c an change these v alues as appr opriate. 4. Enable Overlay Graphics if you w ant to see the geometr y along with the pan plane . Selec t Positiv e or Nega tive to clip the sur faces on the p ositiv e or nega tive side of the cutting plane .Figur e 13.4: Overlaid G eometr y Clipp ed with the P an P lane (p.333) sho ws the geometr y on the p ositiv e side of the cutting plane . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 332Wrapping O bjec tsFigur e 13.4: Overlaid G eometr y Clipp ed with the P an P lane 5. Selec t the r egions t o be analyz ed in the Region selec tion list. By default , all r egions ar e selec ted. In c ases compr ising a lar ge numb er of C artesian r egions , you c an pan thr ough selec ted r egions inst ead. 6. Click Pan to star t the plane mo vemen t thr ough the selec ted r egions . Alternatively, use the ar row butt ons or the slider t o manually mo ve the pan plane t o a par ticular location. The in terior of the C artesian gr id is displa yed on e very position of the plane dur ing its mo vemen t through the r egion. Incr ease (or decr ease) the Incr emen t value t o incr ease (or decr ease) the sp eed of mo vemen t of the plane . Figur e 13.5: Leak D etection U sing the P an R egions D ialog Box (p.333) sho ws ho w the leak age c an be det ected using the Pan Regions dialo g box. If, at an y position of the plane , the c olor of the region is seen inside the geometr y, ther e ma y be a leak or hole in the C artesian gr id. Figur e 13.5: Leak D etection U sing the P an Regions D ialo g Box 333Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.The Wrapping P rocess7. Adjust the plane a t the p osition wher e the leak is seen on the plane . Warning The Pan Regions dialo g box only enables y ou t o know whether or not ther e is a leak or hole in the geometr y. If the geometr y has a hole or leak, you need t o find its e xact location and fill it. Closing holes Options f or closing or op ening the holes ar e in the Operations group b ox: •You use the Wetted H oles group b ox to traverse the holes det ected, or t o globally pa tch or op en all the holes . –Click Draw A ll to view all the w etted holes det ected. –Click First to view the first hole .The displa y will b e limit ed t o the r egion of the hole . Click Next repeatedly t o traverse all the w etted holes and e xamine them individually . –Click Patch A ll to aut oma tically pa tch all the w etted holes det ected. –Click Open A ll to op en all the w etted holes det ected (when the holes iden tified do not r epresen t actual holes). •You use the Selec ted H oles or Create Patch group b ox to close the displa yed hole individually . –Click Patch to aut oma tically close the cur rently displa yed hole . –Click Open if the cur rently displa yed hole do es not r epresen t an ac tual hole . Opening a hole enables you t o indic ate tha t the appr oxima ted w etted r egion should pr opaga te thr ough the c onfigur ation de- tected as a hole . –Click Ignor e if the cur rently displa yed hole is not r elevant for the objec t wr apping/sewing op eration. –Click Cylinder ... to op en the Cylinder (p.316) dialo g box to create a c ylindr ical sur face to fix the hole . •You use the Trace to Points group b ox to locate holes or leaks b y tracing a pa th fr om the Material P oint to a selec ted Target P oint through all the objec ts. Even af ter you fix the holes/leaks , you c an use the Trace to Points options t o verify tha t no tin y leaks r emain. 1. Selec t a p oint from the Target P oints selec tion list and click Trace. The pa th c onnec ting the tar get p oint to the ma terial p oint will b e highligh ted and will pass through the hole/leak. 2. Fix the hole using the options in the Wetted H oles ,Selec ted H oles , or Create Patch group b ox, as appr opriate. 3. Click Update in the Wetted S urface group b ox to up date the w etted sur face represen tation. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 334Wrapping O bjec ts4. Click Update in the Trace to Points group b ox and then click Trace again t o locate an y remaining holes/leaks . 5. Repeat the hole fixing st eps as needed t o ensur e no holes/leaks r emain. •You use the options in the Wetted S urface group b ox to view the appr oxima te represen tation of the volume or r egion of in terest based on the objec ts and ma terial p oint selec ted.You c an also cr eate a mesh objec t using the shr ink-wr ap metho d. –Click Show to view the appr oxima te represen tation of the w etted sur face, based on the objec ts and material p oint selec ted. Enable Overlay Graphics to view the objec t(s) along with the w etted sur face. Click Hide to hide the w etted sur face in the gr aphics windo w. –Click Update to up date the w etted sur face represen tation af ter an y hole fixing op erations (pa tch, open, creating c aps, and so on) ar e performed . Examine the up dated r egion f or fur ther leaks or holes . Fill an y remaining leaks or holes b efore proceeding . After all the holes/leaks ar e fix ed y ou c an pr oceed t o wr ap the objec ts. Specify an appr opriate New Objec t Name and New L abel N ame (if r equir ed). Click Shrink Wrap to cr eate a mesh objec t for the selec ted objec ts using the shr ink-wr ap metho d. Imp ortant The o ctree r efinemen t used t o iden tify and r epair holes o ccurs in a diff erent order than when used t o wr ap objec ts.Thus, using this butt on ma y gener ate a diff erent mesh than if you use the Wrap dialo g box as descr ibed in Shrink Wrapping the O bjec ts (p.335) 13.1.5. Shrink Wrapping the O bjec ts The Wrap dialo g box contains options f or shr ink wr apping the selec ted objec ts. Selec t the objec ts to be wr app ed in the Outline View and then selec t Wrap → Shrink Wrap... from the c ontext sensitiv e menu t o op en the Wrap dialo g box. 1. Selec t the appr opriate option, Individually or Collec tively, from the Target list. These options ar e de- scribed in Creating Individual M esh O bjec ts (p.335) and Creating a C ollec tive Mesh O bjec t (p.336). Creating Individual Mesh O bjec ts The Individually option enables y ou t o cr eate a c onformal sur face mesh f or each objec t selec ted. A w ell-c onnec ted mesh objec t and c orresponding z ones will b e created f or each objec t.The mesh objec t name is the or iginal objec t name with the suffix -mesh .This op eration uses a suitable material p oint tha t is e xternal t o the objec ts selec ted. Hence, any internal v oids or f eatures will be elimina ted.The mesh objec ts cr eated ar e suitable f or repair op erations such as gap or thick ness remo val, or as the final sur face mesh. Figur e 13.6: Wrapping Individual O bjec ts (p.336) sho ws the mesh objec ts cr eated f or geometr y objec ts using the Individually option. 335Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.The Wrapping P rocessFigur e 13.6: Wrapping Individual O bjec ts Creating a C ollec tive Mesh O bjec t The Collec tively option enables y ou t o cr eate a single , well-c onnec ted mesh objec t and c orres- ponding z ones , based on the objec ts selec ted.You c an sp ecify an appr opriate name f or the mesh objec t and a new lab el name . When y ou selec t external in the Material P oint drop-do wn list , a suitable r eference point external to the objec ts is selec ted f or the objec t wr apping op eration. Hence, any internal v oids or f eatures will b e elimina ted.Figur e 13.7: Multiple S olids (p.336) sho ws an e xample with multiple solid objec ts. The aim of the objec t wr apping op eration is t o mesh the solids c onformally and cr eate a single solid c ell z one in the final mesh. Figur e 13.8: Single S olid Sur face (p.337) sho ws the mesh objec t created, wher e the multiple solids ar e unified . Figur e 13.7: Multiple S olids Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 336Wrapping O bjec tsFigur e 13.8: Single S olid S urface Alternatively, you c an use this option t o cr eate the flo w volume , when the sur rounding solids ar e not needed in the final mesh. All objec ts b ounding the flo w volume should b e selec ted f or the wrapping op eration. Selec t the appr opriate ma terial p oint needed t o iden tify the “wetted” region that is the flo w volume .The ma terial p oint can b e defined in the Material P oints dialo g box. Figur e 13.9: Extracting the F low Volume (p.337) sho ws the e xtraction of the in ternal flo w volume for a T-junc tion b y sp ecifying a ma terial p oint and using the Fluid S urface option. Figur e 13.9: Extracting the F low Volume • For the Collec tively option, specify the New O bjec t Name and New Label N ame . 337Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.The Wrapping P rocess2. Set the Resolution F actor.This field c an b e used t o set sampling c oarser or finer than the final sur face mesh. Tip For industr ial siz e pr oblems wher e the geometr y recovery is set t o high, it is r ecommen- ded tha t the r esolution fac tor not b e smaller than 0.7. Imp ortant Wrapping mo dels with a lar ge numb er of fac e zones ma y cause signific ant slo w do wn in performanc e. Merging fac e zones with the same b oundar y conditions will impr ove the effi- cienc y of the wr apping op eration. Imp ortant When wr apping lar ge, comple x geometr ies with small mesh siz es, you ma y need t o incr ease the memor y allo cation. From the Displa y → Controls menu , selec t Shrink Wrap in the Categor ies drop do wn list , and sp ecify a new v alue f or Max O ctree M emor y. Imp ortant By default , the initial b ounding b ox for shr ink wr apping is the global bounding b ox. In multiple session wr apping , a newly cr eated wr app er sur face ma y incr ease the global bounding b ox, which aff ects subsequen t wr app er results .To avoid this issue , go t o the Displa y+Controls menu , selec t Shrink Wrap in the Categor ies drop do wn list , and cho ose selec tion for the Initial B ounding B ox. You c an use the c ommand /objects/wrap/wrap to cr eate the mesh objec t. Specify the objec ts to be wr app ed and other r elevant par amet ers. The c ommand /objects/wrap/set/shrink-wrap-rezone-parameters enables y ou t o set the par amet ers f or impr oving the mesh objec t sur face qualit y using r ezoning .The geometr y objec t zones will b e separ ated based on the separ ation angle sp ecified t o impr ove the f eature impr inting on the mesh objec t. 13.1.6. Impr oving the M esh O bjec ts The options in the Impr ove dialo g box enable y ou t o impr ove the sur face mesh qualit y of mesh objec ts. The wr app er sur face created af ter impr inting is of go od qualit y and it r epresen ts the input geometr y very well in most r egions . However, you c an impr ove it fur ther in some r egions of the geometr y such as shar p corners and cur ves.The p ost wr apping impr ovemen t op erations allo w you t o impr ove the wrapp er sur face by performing v arious op erations such as smo othing , swapping , infla ting thin r egions , remo ving cr osso vers, and so on. 1. Selec t the mesh objec ts in the Outline View. Right-click and selec t Wrap → Impr ove... from the c ontext sensitiv e menu . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 338Wrapping O bjec ts2. Choose the appr opriate Metho d. •The Smooth and Impr ove option impr oves the mesh b y a c ombina tion of smo othing , swapping , and surface mesh impr ovemen t op erations . Objec t nor mals ar e correctly or iented and island fac es ar e also delet ed.You c an optionally c oarsen the sur face mesh b y sp ecifying a suitable Coarsening F actor. Additional Impr int operations c an b e done t o impr ove feature captur e on the sur face mesh. Note Using the Impr int option ma y result in qualit y det erioration. •The Surface Remesh option impr oves the mesh b y remeshing based on the cur rent siz e field . Objec t normals ar e correctly or iented and island fac es ar e also delet ed. 3. Set Coarsening F actor and Impr int as desir ed. The wr app er sur face created ma y be finer than y ou r equir e in some r egions .You c an c oarsen the mesh in such r egions or globally f or the en tire wr app er sur face.This op eration also r educ es the cell c oun t of the mesh, ther eby reducing the c omputa tion time . 4. Click Impr ove. Note Additional c ontrols c an b e set in the Objec ts categor y in the Displa y → Controls dialo g box for impr oving the mesh objec t qualit y. Enable the Impr ove Q ualit y Aggr essiv ely option t o collapse fac es without pr eser ving boundar y features.This option is disabled b y default. You c an alt ernatively use the c ommand /objects/improve-object-quality . 13.1.7. Objec t Wrapping Options The f ollowing objec t wr apping options ar e available: 13.1.7.1. Resolving Thin R egions D uring O bjec t Wrapping 13.1.7.2. Detecting H oles in the O bjec t 13.1.7.3. Impr oving F eature Captur e For M esh O bjec ts 13.1.7.1. Resol ving Thin R egions D uring O bjec t Wrapping Surfaces in close pr oximit y constitut e thin r egions in the mesh. Examples of thin r egions include shar p corners , trailing edge c onfigur ations , and so on, which ma y not b e recovered accur ately enough during the objec t wr apping op eration and sur face elemen ts ma y span b etween no des on the pr ox- imal sur faces. You c an use the c ommand /objects/wrap/set/include-thin-cut-edges-and-faces to enable b etter recovery of such c onfigur ations dur ing the objec t wr apping op eration. 339Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.The Wrapping P rocess13.1.7.2. Detecting H oles in the O bjec t The c ommand /objects/wrap/set/report-holes? enables y ou t o check f or holes in the objec t created. Holes , if an y will b e reported a t the end of the objec t wr apping op eration. The c ommand /objects/wrap/set/max-free-edges-for-hole-patching enables y ou to set the maximum numb er of fr ee edges in a lo op t o fill the holes . The c ommand /objects/wrap/check-holes enables y ou t o check f or holes in the objec ts.The numb er of hole fac es mar ked will b e reported. 13.1.7.3. Impr oving F eatur e Captur e For Mesh O bjec ts The c ommand /objects/improve-feature-capture enables y ou t o impr int the edges c om- prising the mesh objec t on t o the objec t fac e zones t o impr ove feature captur e for mesh objec ts.You can sp ecify the numb er of impr inting it erations t o be performed . Note The geometr y objec ts used t o cr eate the mesh objec t should b e available when the im- prove-feature-capture command is in voked. Additionally , the fac e zones c ompr ising the objec ts should b e of t ype other than geometr y. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 340Wrapping O bjec tsChapt er 14: Creating a M esh After reading the b oundar y mesh and p erforming the nec essar y mo dific ations (such as mer ging duplic ate nodes, edge sw apping) y ou will cr eate the v olume mesh. Depending on the t ype of mesh y ou ar e star ting fr om (b oundar y mesh only , boundar y mesh with hexahedr al cells in one or mor e regions , and so on), you c an aut oma tically gener ate the mesh, manually gener ate the mesh st ep b y step, or use a c ombina tion of manual and aut oma tic c ommands . You c an cr eate se veral types of meshes c ompr ising diff erent elemen t types.The meshing str ategy and the use of the Auto M esh tool ar e descr ibed in this chapt er. Information on ho w to deal with thin r egions , quad-t et tr ansition elemen ts (p yramid and non-c onformal meshing), and cr eation of a hea t exchanger zone ar e also descr ibed. Detailed descr iptions of meshing t echniques such as pr ism meshing , tetrahedr al and he xcore meshing options , and so on ar e descr ibed in subsequen t chapt ers. 14.1. Choosing the M eshing S trategy 14.2. Using the A uto Mesh D ialog Box 14.3. Gener ating a Thin Volume M esh 14.4. Gener ating P yramids 14.5. Creating a N on-C onformal In terface 14.6. Creating a H eat Exchanger Z one 14.7. Parallel M eshing 14.1. Choosing the M eshing S trategy You c an use a v ariety of c ell shap es to mesh the domain: 341Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Figur e 14.1: Possible M esh C ell S hap es A mesh c onsisting en tirely of t etrahedr al elemen ts is a t etrahedr al mesh, and a mesh with an y combin- ation of c ell shap es is r eferred t o as a h ybrid mesh . Before gener ating a v olume mesh, det ermine the shap es tha t are appr opriate for the c ase y ou ar e solving , then f ollow the instr uctions f or cr eating the r equir ed c ell t ypes. Most c ases will fall in to one of the f ollowing c ategor ies: 14.1.1. Boundar y Mesh C ontaining Only Triangular F aces 14.1.2. Mixed B oundar y Mesh 14.1.3. Hexcore Mesh 14.1.4. CutCell M esh 14.1.5. Additional M eshing Tasks 14.1.6. Inser ting I sola ted N odes in to a Tet M esh 14.1.1. Boundar y M esh C ontaining Only Triangular F aces If you r equir e a high mesh r esolution in some p ortion of the domain, such as a b oundar y layer, you can obtain an efficien t and b etter qualit y mesh b y meshing tha t portion with pr isms (w edges) and then meshing the r est of the domain with t etrahedr a (tets). The r esulting mesh is r eferred t o as a visc ous hybrid mesh. The pr ocedur e is as f ollows: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 342Creating a M esh1.Build one or mor e layers of pr isms , star ting fr om the appr opriate boundar y (or b oundar ies). Refer to Gener ating P risms (p.367) for details . 2.Create a domain enc ompassing the r egion t o be meshed with t etrahedr a. Refer to Using D omains t o Group and M esh B oundar y Faces (p.468) for details . 3.Gener ate the t ets in the selec ted domain using either an aut oma tic t et mesh gener ation, a manual t et mesh gener ation, or a c ombina tion of the t wo. Refer to Gener ating Tetrahedr al M eshes (p.399) for details . Figur e 14.2: Mesh with P risms in a B oundar y La yer R egion (p.343) sho ws se veral la yers of pr isms in a portion of a mesh cr eated in this manner .The pr isms e xtend thr oughout the en tire region b ounded by the quadr ilateral fac es, but only a f ew of them ar e sho wn her e. Figur e 14.2: Mesh with P risms in a B oundar y Layer Region The sur face mesh or iginally c ontained only tr iangular fac es.The quadr ilateral fac es ar e created aut o- matically when the pr isms ar e built on the tr iangular fac es. If the quadr ilateral fac es of the pr isms do not lie on the e xternal b oundar y of the domain (tha t is, if the pr ism r egion b egins and/or ends in the in terior of the domain), create a la yer of tr ansitional p yr- amids b etween st eps 1 and 2. Refer to Gener ating P yramids (p.352) for details . If you ha ve no sp ecial b oundar y layer resolution r equir emen ts, you c an gener ate a mesh c onsisting entirely of t etrahedr a (see Figur e 14.3: Sur face M esh C ontaining Only Tetrahedr a (p.343)).You c an use the aut oma tic t etrahedr al mesh gener ation pr ocedur e, the manual pr ocedur e, or a c ombina tion of both. Refer to Gener ating Tetrahedr al M eshes (p.399) for details . Figur e 14.3: Surface M esh C ontaining Only Tetrahedr a 14.1.2. Mixed B oundar y M esh Start from a b oundar y mesh tha t contains tr iangular and quadr ilateral fac es as w ell as he xahedr al cells in the quadr ilateral fac e regions .The r esulting mesh is r eferred t o as a zonal hybr id mesh . 1.Add a la yer of p yramids t o the quadr ilateral boundar y fac e zone tha t lies b etween the he xahedr al region and the adjac ent region t o be meshed with t etrahedr a.This cr eates the tr iangular b oundar y fac e zone that is r equir ed t o create tetrahedr a in the adjac ent region. Refer to Gener ating P yramids (p.352) for details . 2.Create a domain enc ompassing the r egion t o be meshed with t etrahedr a. Refer to Using D omains t o Group and M esh B oundar y Faces (p.468) for details . 3.Gener ate the t etrahedr a in the selec ted domain using either aut oma tic or manual t et mesh gener ation, or a c ombina tion of b oth. Refer to Gener ating Tetrahedr al M eshes (p.399) for details . Figur e 14.4: Sur face M esh (p.343) sho ws the sur face mesh f or a p ortion of a gr id containing he xahedr a, pyramids , tetrahedr a, and pr isms tha t was cr eated on a plenum f eeding a v alve-port cylinder . Figur e 14.4: Surface M esh 343Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Choosing the M eshing S trategy•The less c omplic ated plenum pip e on the lef t of the figur e is meshed using he xahedr al cells. •The mor e comple x valve port (valve not visible b ecause it is inside the sur rounding pip e) is meshed using tetrahedr a. •Pyramids ar e used as a tr ansition b etween the he xahedr al gr id for the plenum and the t etrahedr al gr id for the v alve port.This tr ansition o ccurs wher e the tr iangular and quadr ilateral fac es meet in the middle of the figur e. •Additionally , the quadr ilateral fac es pr oduced b y extending tr iangular fac es in the c ylinder (tha t is, the quadr ilateral sides of the r esulting pr ism w edges) c an b e seen in the far r ight of the figur e. 14.1.3. Hexcore M esh The he xcore mesh f eatures a t etrahedr al/h ybrid mesh adjac ent to walls and a C artesian mesh in the core flo w region. Figur e 14.5: Hexcore M esh (p.344) sho ws the t ypic al he xcore mesh. The he xcore meshing scheme cr eates a mesh c onsisting of t wo regions: •An inner r egion c omp osed of r egular C artesian c ells. •An out er region c onsisting of t etrahedr al elemen ts. Figur e 14.5: Hexcore M esh Wedge elemen ts ar e created only when b oundar y layers ar e attached on fac es pr e-meshed with tr ian- gular elemen ts. It combines the aut oma tion and geometr ic fle xibilit y of t etrahedr al/h ybrid meshes with gr eatly r educ ed c ell c oun ts in man y applic ations .The he xcore mesh is most b eneficial in geometr ies with lar ge op en spac es, as in aut omotiv e, aer ospac e, and HV AC applic ations . Refer to Gener ating the Hexcore M esh (p.413) for details . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 344Creating a M esh14.1.4. CutC ell M esh CutCell meshing is a gener al-pur pose he x-dominan t meshing t echnique tha t can b e used inst ead of tetrahedr al or he xcore meshing , without r equir ing a v ery high-qualit y sur face mesh as a star ting p oint. This metho d uses a dir ect sur face and v olume appr oach without the need of cleanup or dec omp osition, ther eby reducing the tur naround time r equir ed f or meshing . A k ey feature is the lar ge fr action of he x cells in the mesh. Figur e 14.6: CutC ell M esh Refer to Gener ating the C utCell M esh (p.433) for details . 14.1.5. Additional M eshing Tasks Additional meshing tasks tha t can b e handled ar e: •If you ha ve a c omplet e volume mesh and w ant to extend some p ortion of the domain (f or e xample , incr ease the length of an inlet pip e), you c an gr ow one or mor e layers of pr isms fr om the cur rent external (quadr i- lateral or tr iangular) b oundar y. Figur e 14.7: Extending an Existing Tetrahedr al M esh U sing P risms (p.345) sho ws a r egion of pr isms (wedges) e xtended fr om the tr iangular fac e zone tha t bounds a t etrahedr al region. Figur e 14.7: Extending an E xisting Tetrahedr al M esh U sing P risms •Unless ther e is a r eason t o use he xahedr al cells in the quad r egions , it is pr eferable t o convert a mix ed tri/quad b oundar y mesh t o an all-tr i boundar y mesh and then cr eate a t etrahedr al mesh f or a 3D b oundar y mesh c onsisting of only tr iangular fac es. Use the Triangula te Zones dialo g box or the c ommand /boundary/remesh/triangulate to convert quad fac e zones t o tri fac e zones . You c an then use the Boundar y Impr ove dialo g box to impr ove the sk ewness of the tr iangular boundar y zone cr eated. 345Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Choosing the M eshing S trategy•You ma y cho ose t o use a non-c onformal in terface to define the c omputa tional domain. This t ype of in terface enables y ou t o relax the r equir emen t for p oint-to-point ma tching a t the in terface between the meshes , as illustr ated in Figur e 14.8: Example of a N on-C onformal In terface (p.346). Figur e 14.8: Example of a N on-C onformal In terface This f eature of r elaxing the r equir emen t for p oint-to-point ma tching a t the in terface between the meshes is par ticular ly useful in par ametr ic studies wher e you w ant to change an isola ted r egion of the domain without changing the en tire mesh. The pr ocedur e is as f ollows: 1.Read the meshes in meshing mo de in F luen t.These meshes need not shar e no des, edges , faces, or c ells. 2.Create the v olume mesh using an appr opriate meshing str ategy.You c an also cr eate domains f or each indep enden t mesh r egion and mesh the individual domains separ ately. 3.Separ ate the r egion of non-c onformal in terface into new fac e zones . Use Boundar y → Manage to change the fac e zone t ype of the t wo sur faces tha t will b e treated as non-c onformal t o interface. 4.Transf er the mesh t o solution mo de in F luen t and cr eate the non-c onformal in terface using the Mesh Interfaces dialo g box. Refer to Mesh In terfaces D ialog Box (p.3852 ) for details . 14.1.6. Inser ting I sola ted N odes in to a Tet M esh To add no des t o the mesh without sp ecifying the fac es, you c an cr eate a b oundar y zone in the boundar y mesh (in the pr ogram tha t created it) just f or this pur pose, then y ou c an in troduce the no des asso ciated with these fac es. This f eature is useful f or clust ering no des (and ther efore cells) in a c ontrolled manner .Figur e 14.9: Mesh Gener ated U sing I sola ted N odes t o Concentrate Cells (p.348) sho ws a mesh tha t was gener ated using this metho d to clust er the no des b ehind the w edge . A mesh tha t was gener ated f or the same geometr y without clust ering is sho wn in Figur e 14.10: Mesh G ener ated Without U sing I sola ted N odes (p.348). You c an f ollow either of the t wo pr ocedur es to inser t isola ted no des in to a mesh: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 346Creating a M esh•Delete the fac e zone b efore meshing . •Introduce the no des using fac e zones af ter meshing . Deleting the F ace Zone B efor e Meshing This pr ocedur e is as f ollows: 1. Delete the fac e zone , but lea ve the asso ciated no des. Disable Delet e Nodes in the Manage F ace Zones dialo g box to retain these no des. Note By default , the unused no des ar e delet ed when the fac es of the z one ar e delet ed. 2. Disable Delet e Unused N odes in the Tet dialo g box and gener ate the v olume mesh. Note By default , unused no des will b e delet ed dur ing the aut oma tic meshing . The no des will b e in troduced when y ou initializ e the mesh. When y ou use this pr ocedur e,all nodes must b e inser ted in to the mesh or the initializa tion will fail. Warning Do not plac e isola ted no des t oo close t o the b oundar y or t o other no des. 347Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Choosing the M eshing S trategyFigur e 14.9: Mesh G ener ated U sing I sola ted N odes t o Conc entrate Cells Figur e 14.10: Mesh G ener ated Without U sing I sola ted N odes Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 348Creating a M eshIntr oducing the N odes Using F ace Zones A fter Meshing This pr ocedur e is as f ollows: 1. Create a sub domain tha t do es not include the fac e zones used t o control the mesh densit y. 2. Create the v olume mesh using the sub domain. 3. Activate the global domain. 4. Introduce the additional no des using the t ext command:/mesh/modify/mesh-nodes-on-zone . Imp ortant The /mesh/modify/mesh-nodes-on-zone command will delet e the fac es asso ci- ated with the fac e zone . 14.2. Using the A uto M esh D ialo g Box The Auto M esh dialo g box enables y ou t o aut oma tically cr eate the v olume mesh using the diff erent mesh elemen ts available .This dialo g box can used f or gener ating the v olume mesh based on fac e zones or based on a mesh objec t and r elevant ma terial p oints. For mor e detail ab out objec t-based mesh gener ation, refer to Objec ts (p.223). The gener ic pr ocedur e for using the Auto M esh dialo g box for cr eating the v olume mesh is as f ollows: 1. Determine the meshing appr oach (fac e zone based or objec t based) and the mesh elemen ts requir ed f or the par ticular c ase. 2. Open the Auto M esh dialo g box using the Mesh → Auto M esh... menu it em or fr om the c ontext-sensitiv e menu a vailable b y right-click ing on an y Mesh O bjec t, or its Cell Z ones or Volumetr ic Regions branch in the Outline View. 3. Selec t the appr opriate option in the Objec t drop-do wn list in the Auto Iden tify Volume group b ox. a. For the fac e zone based meshing appr oach, ensur e tha t none is selec ted in the Objec t drop-do wn list. b.For the objec t based meshing appr oach, selec t the appr opriate mesh objec t in the Objec t drop-do wn list. Enable/disable Keep S olid C ell Z ones and Keep D ead C ell Z ones as r equir ed. Tip If you op en the A uto M esh dialo g box from the c ontext-sensitiv e menu in the Model tr ee, the M esh O bjec t is aut oma tically selec ted. 4. Selec t the appr opriate option in the Grow P risms drop-do wn list in the Boundar y Layer M esh group box. 349Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the A uto Mesh D ialog Boxa. Retain the default selec tion of none if you do not need t o gr ow pr ism la yers f or the cur rent meshing appr oach. b.Selec t scoped if you w ant to sp ecify objec t-sp ecific pr ism par amet ers. Click Set... to op en the Scoped Prisms dialo g box and define the pr ism par amet ers and sc ope. Refer to Prism M eshing Options f or Scoped P risms (p.393) for details . c.Selec t zone-sp ecific if you w ant to sp ecify z one-sp ecific pr ism par amet ers. Click Set... to op en the Prisms dialo g box and sp ecify the z one-sp ecific pr ism par amet ers. Refer to Procedur e for C reating Zone-based P risms (p.369) for details . 5. Selec t the appr opriate quad-t et tr ansition elemen ts fr om the Quad Tet Transition list. Click Set... to op en the Pyramids dialo g box or the Non C onformals dialo g box (dep ending on the selec tion) and sp ecify the appr opriate par amet ers. Refer to Creating P yramids (p.353) and Creating a N on-C onformal In ter- face (p.357) for details . 6. Selec t the appr opriate option fr om the Volume F ill list. Click Set... to op en the Tet,Hexcore, or Poly dialo g box (dep ending on the selec tion) and sp ecify the appr opriate par amet ers. Refer to Initializing the Tetrahedr al M esh (p.406),Refining the Tetrahedr al M esh (p.407),Controlling H excore Paramet ers (p.416), and Steps f or C reating the P olyhedr al M esh (p.424) for details . Note The No Fill option is not a vailable f or objec t based v olume meshing . 7. Specify the appr opriate Volume F ill Options . a. For the Tet or Poly metho ds, set the f ollowing: •Selec t the appr opriate option f or Cell S izing . –Size Field specifies tha t the c ell siz e is det ermined based on the cur rent siz e-field . –Geometr ic specifies tha t the c ell siz e in the in terior of the domain is obtained b y a geometr ic growth fr om the closest b oundar y acc ording t o the gr owth r ate sp ecified . Set the Growth R ate requir ed. •Specify the Max C ell L ength . Click Comput e to comput e the maximum c ell siz e based on the mesh objec t. b.For the Hexcore metho d, set the f ollowing: •Selec t the appr opriate option f or Type. Retain the default selec tion of Cartesian or selec t the Octree type. •Set the numb er of Buff er L ayers and Peel L ayers. •Specify the Max C ell L ength for the C artesian appr oach. Click Comput e to comput e the maximum cell siz e based on the mesh objec t. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 350Creating a M eshSpecify the Min C ell L ength for the O ctree appr oach. c.For the Poly-H excore metho d, set the f ollowing: •Specify the numb er of Buff er L ayers and Peel L ayers. •Specify the Min C ell L ength for the p oly-he xcore appr oach. The h ybrid p oly-he xcore volume meshing metho d is a c ombina tion of the e xisting p oly and the o ctree he xcore meshing algor ithms , and is a vailable f or ser ial pr ocessing only , with objec t based w orkflows when the Grow P risms option is set t o none or scoped. While similar t o the Octree mesh option, the Poly-H excore option le verages the use of he xcore volume meshing and uses a p olyhedr on tr ansitional mesh r ather than a t etrahedr on tr ansitional mesh. 8. For objec t-based meshing enable Merge C ell Z ones within Regions to create a single c ell z one within a region, or disable t o keep the c ell z ones separ ate. For z one-based meshing , enable Merge C ell Z ones to cr eate a single c ell z one within a domain, or disable t o keep the c ell z ones separ ate. Note For objec t-based meshing and par allel pr ocessing , after y our mesh is distr ibut ed, this option is ac tive aut oma tically. To apply par allel pr ocessing of the mesh, enable Auto Partition (P arallel M eshing) .This option is only a vailable f or Poly-H excore volume fill (enabled b y default), or f or z one-based meshing with Tet and pr ism v olume fill, and is not available f or the pur e tetrahedr a, polyhedr a, or he xcore fill metho ds.The Auto Partition (P arallel M eshing) option is also only a vailable when the numb er of par allel pr ocessors is gr eater than 1). Enabling this setting will also enable the Auto par tition option in the Parallel M esh S ettings dialo g box (see Auto Partitioning (p.359)). Disable the Auto Partition (P arallel M eshing) option if y ou ar e in terested in only gener ating the v olume mesh in serial mo de. 9. Click Mesh to aut oma tically cr eate the mesh. Alternatively, you c an use the c ommand /mesh/auto-mesh to gener ate the mesh aut oma tically. Specify a mesh objec t name f or objec t-based aut o mesh; if no name is giv en, face zone based aut o mesh is p erformed . Specify the mesh elemen ts to be used when pr ompt ed. Specify whether t o mer ge the c ells in to a single z one or k eep the c ell z ones separ ate. For fac e zone based meshing , specify whether t o aut oma tically iden tify the domain t o be meshed based on the t opology inf ormation. Note You c an sp ecify the meshing par amet ers f or the mesh elemen ts (pr isms , pyramids or non-c onformals , tet, or he x) using either the r espective dialo g boxes or the asso ciated text commands pr ior t o using the auto-mesh command . 351Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the A uto Mesh D ialog Box14.3. Gener ating a Thin Volume M esh Thin Volume M esh creates sw eep-lik e mesh f or a b ody occup ying a thin gap .You define b oundar y face zones f or sour ce and tar get such tha t the sour ce fac e nor mal should p oint to the tar get. The sour ce face mesh ma y be triangles or quads . Four other c ontrols ar e then used b y Fluen t Meshing t o gr ow the volume mesh fr om the sour ce zone t o the tar get z one . To gener ate a Thin Volume M esh: 1. Check the sour ce boundar y mesh t o ensur e tha t free no des or fac es with high sk ewness do not e xist. See Manipula ting B oundar y Nodes (p.273) and Determining Sur face Mesh Q ualit y (p.492) for details . 2. Open the Thin Volume M esh dialo g box. Mesh → Thin Volume M esh 3. Selec t the Sour ce Boundar y Face Zone from the list. 4. Selec t the Target B oundar y Face Zone from the list. 5. Specify the Gap Thick ness . •If set t o 0, the mesher will aut oma tically c alcula te the gap thick ness . •If non-z ero, the G ap Thick ness defines the maximum separ ation b etween sour ce and tar get z ones in the sw ept-mesh r egion. 6. Specify the Numb er of D ivisions between sour ce and tar get fac es. 7. Specify the Growth R ate between adjac ent layers. 8. Choose Remesh o verlap z ones behavior. Remesh o verlap z ones r eplac es an y overlapp ed par t of the surface mesh on the tar get and adjac ent fac es. Original meshes in these ar eas ar e replac ed. 9. Click Create to calcula te the thin solid mesh. 10. Click Draw to displa y the mesh in the gr aphics windo w of the user in terface. 14.4. Gener ating P yramids A pyramid has a quadr ilateral fac e as its base and f our tr iangular fac es e xtending fr om the sides of the quadr ilateral up t o a single p oint ab ove the base . See Figur e 14.11: Pyramid C ell—T ransition fr om a Hexahedr on t o a Tetrahedr on (p.353). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 352Creating a M eshFigur e 14.11: Pyramid C ell—T ransition fr om a H exahedr on t o a Tetrahedr on To gener ate a c onformal mesh with a r egion of t etrahedr al cells adjac ent to a r egion of he xahedr al cells, you will first cr eate a la yer of p yramids as a tr ansition fr om quadr ilateral fac es to triangular fac es. After cr eating a single la yer of p yramids , the r esulting tr iangular fac es will b e used t o cr eate tetrahedr a. To cr eate pyramids , you need t o sp ecify the b oundar y from which the p yramids will b e built , the metho d for det ermining the t op v ertex of each p yramid , and the p yramid heigh t. 14.4.1. Creating P yramids 14.4.2. Zones C reated D uring P yramid G ener ation 14.4.3. Pyramid M eshing P roblems 14.4.1. Creating P yramids The pr ocedur e for cr eating a la yer of p yramids fr om a quadr ilateral b oundar y zone is as f ollows: 1.Check the asp ect ratio limits of the b oundar y fac e zones on which y ou need t o build p yramids . Rep ort → Size Field The use of a high-asp ect-ratio quadr ilateral for the base of a p yramid pr oduces sk ewed tr iangular faces tha t can c ause pr oblems dur ing the t etrahedr al mesh gener ation. If the maximum quadr ilat- eral fac e asp ect ratio is much gr eater than 10, you will need t o regener ate them. •If the fac es w ere created in a diff erent preprocessor , retur n to tha t applic ation and tr y to reduc e the aspect ratio of the fac es in question. •If the fac es w ere created dur ing the building of pr ism la yers, rebuild the pr isms using a mor e gr adual growth r ate. 2.Selec t the appr opriate quadr ilateral boundar y zones in the Boundar y Zones selec tion list in the Pyramids dialo g box. Mesh → Pyramids Click Draw to view the selec ted z ones . If the quadr ilateral zone y ou r equir e do es not app ear in the list , use the /boundary/reset- element-type text command t o up date the t ype of the z one . It is p ossible tha t the quadr ilateral zone ma y not b e recogniz ed the due t o changes made t o the b oundar y mesh. 353Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Gener ating P yramidsFor e xample , if y ou separ ate a mix ed (tr i and quad) fac e zone in to a tr i fac e zone and a quad fac e zone , each of these will b e iden tified as a mix ed z one .You need t o reset the elemen t type for the quad z one f or it t o be recogniz ed and included in the Boundar y Zones selec tion list. 3.Selec t the appr opriate metho d for det ermining the p yramid v ertex location in the Options list. The skewness metho d is selec ted b y default , and is appr opriate for most c ases . 4.Specify the heigh t of the p yramids b y setting the Offset Sc aling value . 5.Click Create.The new p yramid c ell z one and the new fac e zones cr eated will b e reported in the c onsole . You c an then use the Displa y Grid dialo g box to view these new z ones . Displa y → Grid 6.Change the b oundar y type of the quadr ilateral base z one t o the appr opriate type (if nec essar y). Boundar y → Manage Note Because y ou built c ells ne xt to the quadr ilateral base z one , its or iginal b oundar y type may no longer b e correct. Imp ortant The p yramids should b e aut oma tically cr eated on the appr opriate side of the sp ecified boundar y zones . If the p yramids ar e on the wr ong side , do the f ollowing: 1.Delete the newly cr eated z ones r elated t o the p yramids . 2.Reverse the nor mal dir ection on the quadr ilateral boundar y wher e the p yramids ar e being built (using the Flip N ormals option in the Manage F ace Zones dialo g box). 3.Recreate the p yramids . 14.4.2. Zones C reated D uring P yramid G ener ation When p yramids ar e gener ated, at least t wo new z ones ar e created: a cell z one c ontaining the p yramid cells and a fac e zone c ontaining the tr iangular fac es of the p yramids . The f ollowing z ones will b e created dur ing p yramid gener ation: •The c ell z one c ontaining the p yramids (pyramid-cells-n ). •The fac e zone c ontaining the tr iangular fac es of the p yramid c ells (base-zone-pyramid-cap-n ). For e xample , if the p yramids w ere built fr om the quadr ilateral fac e zone wall-4 , the y will b e plac ed in a new z one c alled wall-4-p yramid-c ap-9 (wher e the 9 is the z one numb er assigned). •The fac e zones c ontaining the p yramid sides tha t use e xisting fac es fr om the or iginal b oundar y mesh (base-zone-pyramid-side:n ), wher e,n is the z one numb er assigned . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 354Creating a M eshFor e xample , if tr iangular b oundar y fac es fr om the z one wall-3 are used , the y will b e plac ed in a new z one c alled wall-3-p yramid-side-6 (wher e the 6 is the z one numb er assigned). Imp ortant If you include the pyramid-side boundar y zones when defining the domain in which you ar e going t o gener ate a t etrahedr al mesh, the t etrahedr al meshing will fail. 14.4.3. Pyramid M eshing P roblems Most pr oblems asso ciated with cr eating p yramid la yers manif est themselv es in the subsequen t process of gener ating the t etrahedr al mesh. Rapid C hanges in Volume Rapid changes in the siz es of c ells ha ve a nega tive influenc e on the c onvergenc e and accur acy of the numer ical solution. The p yramid la yer cr eation c an pr oduce rapid v ariations in c ell v olume in the f ol- lowing situa tions: •If the quadr ilateral sur face mesh has fac es with r apid changes in siz e. •If ther e is gr eat dispar ity between the siz es of the quadr ilateral fac es and the neighb oring tr iangular fac es used in the p yramid cr eation. You c an a void the r apid v ariation in v olume b y creating quadr ilateral and neighb oring tr iangular gr ids with smo oth v ariations in fac e siz e. Intersec ting F aces If the quadr ilateral sur face used t o cr eate pyramids has highly c oncave corners , the r esulting p yramids may pier ce each other and/or neighb oring b oundar y fac es: 355Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Gener ating P yramidsFigur e 14.12: Pyramid C ells In tersec ting E ach O ther and B oundar y In such c ases , you c an either incr ease the r esolution t o pr event the in tersec tions or alt er the meshing strategy. An alt ernative is t o separ ate the quadr ilaterals in the c oncave corner in to another z one (using techniques descr ibed in Separ ating B oundar y Zones (p.303) or Modifying the B oundar y Mesh (p.280)), create triangular fac es fr om the quadr ilateral fac es using the /boundary/remesh/triangulate text command , and then cr eate pyramids . The sk ewness-based p yramid cr eation will use the e xisting tr iangular fac es and a void the in tersec tion problem (see Figur e 14.13: Fixed In tersec ting P yramid C ells U sing Triangular F aces (p.356)). Figur e 14.13: Fixed In tersec ting P yramid C ells U sing Triangular F aces Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 356Creating a M eshHigh Asp ect Ratio Creating p yramids on quadr ilateral fac es with v ery high asp ect ratios r esults in highly sk ewed tr iangular faces. Subsequen t attempts t o cr eate a t etrahedr al mesh fr om these elemen ts will pr oduce a p oor- qualit y mesh. Irrespective of the metho d used t o gener ate the quadr ilaterals, mo dify the meshing str ategy to reduc e the asp ect ratio using an e xternal gr id gener ation pack age or the pr ism la yer capabilit y. 14.5. Creating a N on-C onformal In terface For meshes c ontaining b oth he xahedr al and t etrahedr al elemen ts, you c an gener ate a non-c onformal interface to avoid cr eating in termedia te pyramids as tr ansition elemen ts b etween the quadr ilateral and triangular sur faces.You c an also cho ose t o cr eate a non-c onformal in terface when gr owing pr isms fr om a boundar y on a sur face mesh, to avoid quad fac es in the domain t o be meshed .The sur faces c ontaining quad elemen ts will b e copied and then tr iangula ted while k eeping the or iginal sur faces in tact.The fr ee nodes of the tr iangula ted sur face will then b e mer ged with the no des on the or iginal sur face mesh. Both sur faces will then b e converted t o in terface type. The options in the Non C onformals dialo g box enable y ou t o cr eate a non-c onformal in terface. 14.5.1. Separ ating the N on-C onformal In terface Between C ell Z ones 14.5.1. Separ ating the N on-C onformal In terface Between C ell Z ones The c ommand /mesh/non-conformals/separate enables y ou t o separ ate the fac e zones a t the non-c onformal in terface between the c ell z ones sp ecified . Specify the c ell z ones wher e the in terface is not c onformal, an appr opriate gap distanc e (absolut e or r elative), and the cr itical angle t o be used for separ ating the fac e zones .The gap distanc e used f or the separ ation is the lar ger v alue of the absolut e gap distanc e sp ecified and the r elative gap distanc e times the a verage lo cal edge length. You c an also choose t o or ient the b oundar y fac e zones af ter separ ation and additionally wr ite a jour nal file dur ing the separ ation op eration. This jour nal file c an then b e read in solution mo de t o cr eate the mesh in ter- faces aut oma tically. The separ ated fac e zones will b e named as f ollows:cell z one 1:c ell z one 2-or ig fac e zone 1 for fac e zone 1 a ttached t o cell z one 1 and cell z one 2:c ell z one 1-or ig fac e zone 2 for fac e zone 2 a ttached to cell z one 2. If the separ ated in terface zone has mor e than one fac e zone , the or iginal fac e zone contributing a lar ger numb er of fac es will b e used f or the name . Invalid c ontact locations will b e sk ipped dur ing the separ ation op eration. The lo cation of the in valid contact will b e reported in the c onsole . 14.6. Creating a H eat Exchanger Z one Many engineer ing sy stems , including p ower plan ts, clima te control, and engine c ooling sy stems t ypic ally contain hea t exchangers . However, for most engineer ing pr oblems , it is impr actical to mo del individual fins and tub es of the hea t exchanger c ore. You c an cr eate a hea t exchanger v olume mesh using the options in the Heat Exchanger M esh dialo g box. 357Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Creating a H eat Exchanger Z oneThe hea t exchanger mesh cr eated c ontains pr isms gener ated fr om a quad split sur face mesh. You need to sp ecify f our p oints (either b y selec ting the lo cations or no des) and the r equir ed in tervals b etween the first selec ted p oint and the each of the r emaining p oints to cr eate the hea t exchanger mesh. A meshed plane is cr eated using the first thr ee sp ecified p oints and the c orresponding in tervals. Prisms are created on the meshed plane using the f ourth p oint and the c orresponding in terval. Mesh → Create → Heat Exchanger ... 1. In the Location group b ox, selec t Position or Nodes to sp ecify the sour ce for lo cation c oordina tes. 2. Click Selec t Points... or Selec t Nodes ... and selec t the f our p oints (no des) in the c orrect order. Imp ortant The or der of selec tion of the p oints is imp ortant because the hea t exchanger z one is created based on the in tervals sp ecified b etween the first selec ted p oint and each of the r emaining p oints. If the p oints ar e not sp ecified in the c orrect order, you will get a heat exchanger z one tha t is diff erent from the r equir ed one . 3. In the Create By group b ox, selec t Interval or Size to setup the mesh densit y. 4. Specify the numb er of in tervals (or mesh siz e) b etween selec ted p oints (no des) 1–2, 1–3, and 1–4, respect- ively. 5. Enable Create Objec t, if you need t o create a mesh objec t for the hea t exchanger mesh z ones cr eated. 6. Click Preview to pr eview the hea t exchanger z ones and mo dify the par amet ers if y ou ar e dissa tisfied with the r esults . 7. Click Create. 8. Specify the pr efix f or the z ones as r equir ed in the Objec t/Zone P refix dialo g box and click OK. The hea t exchanger z ones (pr efixed b y hxc-) are created as sho wn in Figur e 14.14: Creating the H eat Exchanger M esh (p.358). Figur e 14.14: Creating the H eat Exchanger M esh Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 358Creating a M esh14.7. Parallel M eshing If you launched F luen t with par allel pr ocessing f or meshing enabled , you will b e able t o distr ibut e the mesh da ta acr oss the a vailable c omput e no des, or r ecombine the mesh da ta as r equir ed. For additional information on sp ecifying par allel pr ocessing , see Starting ANSY S Fluen t Using F luen t Launcher (p.33). The f ollowing options ar e available f or par allel meshing: 14.7.1. Auto Partitioning 14.7.2. Computing P artitions 14.7.3. Controlling the Threads 14.7.1. Auto Partitioning Auto par titioning enables aut oma tic dec omp osition of the mesh in to suitable par titions f or par allel meshing .The pr ism base z ones will b e aut oma tically par titioned if z one-sp ecific pr ism par amet ers or scoped pr ism c ontrols ar e sp ecified .The pr ism mesh will b e gener ated on the r espective comput e nodes. After the pr ism mesh has b een gener ated, the t etrahedr al mesh will b e gener ated on c omput e node 0. Follow these st eps t o gener ate the mesh using aut o-par titioning . 1.Prepar e the sur face mesh f or v olume meshing . Ensur e tha t the mesh qualit y and c onnec tivit y are appr o- priate. 2.Enable Auto Partition in the Parallel M esh S ettings dialo g box. When Auto Partition is enabled , and after volume meshing has o ccur red, several elemen ts of the graphic al user in terface ar e no longer a vailable ( Availabilit y of G raphic al U ser In terface Options After P arallel M eshing (p.360)). Likewise , ther e ar e elemen ts of the t ext user in terface tha t are also no longer a vailable ( Availabilit y of Text Interface Options A fter P arallel M eshing (p.362)). 3.Create the v olume mesh using the options in the Auto M esh dialo g box. Note •Available v olume meshing options include z one-sp ecific or sc oped pr isms , pyramid and non-c onformal quad-t et tr ansition, and t etrahedr al fill. •For objec t-based meshing , the objec t back up c annot b e created and henc e, the mesh objec t surface mesh c annot b e restored la ter. 4.Impr ove the v olume mesh using the options a vailable , if requir ed. 5.Save the mesh or c ase file . Note The c ase file will b e wr itten in HDF5 f ormat and c an b e read only in F luen t solution mode. 359Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Parallel M eshing14.7.1.1. Availabilit y of Gr aphic al User Int erface O ptions A fter P arallel Meshing After aut o par titioning is enabled , and after par allel meshing has o ccur red, the f ollowing it ems in the graphic al user in terface ar e not a vailable as not ed: Unavailable I tems Location Free F ace Displa y (Ribbon) Multi F aces Remesh Patch Options (Ribbon) Separ ate Append F ile(s) Selec t File Dialog (File > Read M esh) Merge N odes Boundar y Menu Intersec t Create Create Modify B oundar y Dialog (Op era- tions)Merge Delet e Collapse Split Swap Prisms Separ ate Face Zones Dialog (Op- tions)Thin Volume M esh Seed Flip N ormals Manage F ace Zones Dialog (Op- tions)Orient Prisms Mesh Menu Thin Volume M esh Pyramids Non-C onformals Tet Hexcore CutC ell Create Tet Impr ove (not a vailable f or the P oly- H excore volume fill metho d, other wise , available f or the Tet volume fill metho d using pr isms)Mesh > Tools Cavity Remesh Impr ove (not a vailable f or the P oly- H excore volume fill metho d, other wise , available f or the Tet v olume fill metho d using pr isms)Mesh > Tools > P rism Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 360Creating a M eshUnavailable I tems Location Split Post Ignor e Tet Impr ove Cavity Split Modify C ells Dialog (Options) Swap Constr uction G eometr y Outline View: Model context menu optionsPeriodicit y CAD A ssemblies Diagnostics Outline View: Model > G eometr y O bjec ts context menu optionsConvert to M esh O bjec t Wrap Remesh Advanc ed CAD A ssociation Diagnostics Outline View: Model > M esh O bjec ts context menu optionsWrap Remesh F aces Join/In tersec t Rec over P eriodic Rest ore Faces Advanc ed CAD A ssociation Join/In tersec t Outline View: Model > M esh O bjec ts > F ace Zone L abels sub-le vel context menu optionsDiagnostics Rec over P eriodic Comput e Outline View: Model > M esh O bjec ts > Volu- metr ic Regions context menu:Valida te Update External B affles Setup Sc oped P risms Diagnostics Outline View: Model > M esh O bjec ts > Volu- metr ic Regions sub-le vel context menu optionsManage Remesh F aces Scoped P risms Tet Hexcore Auto Fill Volume CAD A ssociation 361Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Parallel M eshingUnavailable I tems Location Graphics Toolbars : Constr uct Geometr y Graphics Toolbars : Loop S elec tion M ode Graphics Toolbars : Miscellaneous P ortions of the ContextToolbar 14.7.1.2. Availabilit y of Text Int erface O ptions A fter P arallel Meshing After aut o par titioning is enabled , and after par allel meshing has o ccur red, the f ollowing it ems in the text user in terface ar e not a vailable as not ed: Status Command TUI M enu objects / available check-mesh available delete available delete-all available delete-all-geom available delete-unreferenced-faces-and- edges available extract-edges available list available mer ge-w alls available rename-cell-zone-boundaries-us- ing-labels available rename-object available rename-object-zones available rotate available scale available summary available translate available update mesh / not a vailable auto-mesh-multiple-objects not a vailable auto-prefix-cell-zones available domains/ Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 362Creating a M eshnot a vailable manage/auto-set-active not a vailable manage/get-material-point not a vailable modify/extract-unused-nodes not a vailable modify/list-skewed-cells not a vailable modify/repair-negative-volume- cells not a vailable; available when Auto Partition is disablednon-conformals/ available prepare-for-solve available prism/ not a vailable prism/create not a vailable prism/mark-ignore-faces not a vailable prism/mark-nonmanifold-nodes not a vailable prism/controls/ not a vailable scoped-prisms/ not a vailable tet/ boundary / available delete-unused-nodes not a vailable modify/ 14.7.2. Computing P artitions When the mesh file is initially loaded , all mesh da ta is asso ciated with c omput e no de 0. Comput e the partitions based on the closed r egions in the mesh. Each closed r egion will b e assigned t o the c omput e nodes a vailable with some c onsider ation f or load balancing .When the mesh is distr ibut ed, the mesh data will b e distr ibut ed t o the c omput e no des based on the par titions c omput ed. Combined mesh data is r equir ed f or geometr y and sur face mesh r epair . Follow these st eps t o distr ibut e the mesh acr oss the a vailable c omput e no des. 1.Section the b oundar y zones . Any closed sur face mesh b etween objec ts or b odies ma y ser ve to separ ate sec tions .The domain may be pr e-par titioned (indep enden t creation of separ ate regions), or y ou ma y tak e ad vantage of regions in the geometr y, or y ou ma y main tain a sur face mesh b etween objec ts or b odies . Parallel meshing supp orts non-c onformally c onnec ted b odies if the y can b e iden tified as separ ate bodies .Within a b ody, sur faces must b e conformal. 2.Open the Parallel M esh S ettings dialo g box under Parallel → Mesh S ettings .... 3.Click Comput e Partitions . All the Boundar y Zones will b e assigned t o the a vailable par titions as gr oups of closed r egions . Assignmen t is based on lo cation with some c onsider ation f or load balancing . 363Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Parallel M eshingIf the numb er of closed r egions is less than the numb er of c omput e no des, then the numb er of regions is tak en as the numb er of par titions and the other c omput e no des will b e idle with no mesh. 4.Use the Comput e Node N um,List , and Draw controls t o examine the e xpected mesh distr ibution. 5.Click Distribut e M esh. Mesh da ta will b e distr ibut ed t o the a vailable c omput e no des based on the c omput ed par titions . Note If you r ead in a c ase file (using the File → Read → Case... menu or the /file/read- case command) and then distr ibut e the mesh, boundar y conditions ma y not b e pr e- served. 6.Create your v olume mesh. Note •Available v olume meshing options include z one-sp ecific or sc oped pr isms , pyramid and non-c onformal quad-t et tr ansition, and t etrahedr al fill. Unavailable options will b e gr eyed out. •For objec t-based meshing , any existing objec t back up da ta will b e delet ed and henc e, the mesh objec t sur face mesh c annot b e restored la ter. •If including pr ism la yers, consist ent orientation must b e done b efore computing the v olume mesh. •The mesh cr eated b y par allel pr ocessing is v alid although it ma y ha ve some diff erences when c ompar ed t o a ser ial pr ocessed mesh. 7.If nec essar y to perform geometr y or sur face mesh r epair , use Agglomer ate M esh. Distribut ed mesh da ta will b e recombined in to a single par tition on c omput e no de 0. 14.7.3. Controlling the Threads You c an c ontrol the maximum numb er of thr eads on each machine b y using the Thread C ontrol dialo g box (Figur e 14.15: The Thread C ontrol D ialog Box (p.365)). Parallel → Thread C ontrol... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 364Creating a M eshFigur e 14.15: The Thread C ontrol D ialo g Box You ha ve the f ollowing options when using the Thread C ontrol dialo g box: •Numb er of N ode P rocesses on M achine When this option is chosen, the maximum numb er of thr eads on each machine is equal t o the numb er of ANSY S Fluen t no de pr ocesses on each machine . •Numb er of C ores on M achine This is the default option. When this option is chosen, the maximum numb er of thr eads on each machine is equal t o the numb er of c ores on the machine . ANSY S Fluen t obtains the numb er of c ores from the OS. This ma y be applic able when the multi-thr eaded par t of the c alcula tion is domina ting the c omputa tion time , and the c ontinuous phase c alcula tion is r elatively small, and y ou w ant to take full ad vantage of the c omputa tion r esour ces. For e xample , if y ou ha ve a v ery small c ase with regar d to the numb er of c ells, but a lar ge numb er of par ticles t o be tracked, you ma y want to spa wn one ANSY S Fluen t no de pr ocess on each machine , but use the maximum numb er of c ores in or der to get a go od overall p erformanc e. •Fixed N umb er When this option is chosen, you ma y sp ecify the maximum numb er of thr eads tha t can b e spa wned on each machine in the numb er-en try box below Fixed N umb er.This ma y only b e applic able when you w ant to ha ve fine c ontrol of the numb er of thr eads on each machine; it is not r ecommended in gener al. 365Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Parallel M eshingRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 366Chapt er 15: Gener ating P risms You c an cr eate pr ism c ells star ting fr om either quadr ilateral or tr iangular b oundar y fac es, or b oth. Prisms can b e used t o resolv e a b oundar y layer region of a t etrahedr al mesh. They can b e used t o extend some portion of a domain f or which the v olume mesh alr eady exists (f or e xample , incr ease the length of an inlet pip e), or t o cr eate a v olume mesh b y extrusion. Figur e 15.1: Prism S hap es (p.367) sho ws the t ypes of pr isms tha t can b e gener ated. Figur e 15.1: Prism S hap es To cr eate pr isms , you need t o sp ecify the sur faces fr om which the pr isms will b e built and the par amet ers that control the pr ism gr owth. Details ab out ho w the par amet ers ar e used t o gener ate the pr isms ar e provided in The P rism G ener ation P rocess (p.367). For z one-based pr ism gr owth, the pr isms ar e gr own fr om selec ted b oundar y zones . Growth par amet ers such as off set and gr owth metho ds, prism heigh t, the numb er of la yers, and the dir ection ma y be applied only t o sp ecific z ones . Additional gr owth options including options f or pr ism pr oximit y det ection and splitting c an also b e sp ecified . Instr uctions f or building z one-based pr isms ar e pr ovided in Procedur e for C reating Z one-based P risms (p.369).The additional options ar e descr ibed in Prism M eshing Options for Z one-S pecific P risms (p.373). For objec t-based meshing , use the sc oped pr ism pr ocess t o selec t regions f or pr ism cr eation and set up c ontrols f or the pr ism gener ation. Each c ontrol sp ecifies the off set metho d, prism heigh t, numb er of la yers and gr owth r ate (sc oped pr ism uses the geometr ic gr owth metho d).The sc ope for pr ism cr eation can b e set t o fluid-r egions ,solid-r egions , or sp ecific ally named-r egions .Within the selec ted r egions , you c an gr ow pr ism la yers on only-w alls (default), all-z ones , or the solid-fluid-in terface. Alternatively, you c an gr ow pr ism la yers on selec ted z ones ( selec ted-fac e-zones ) or fac e zone lab els ( selec ted-lab els). The sc oped pr ism c ontrols c an b e read fr om a pr eviously sa ved file or c an b e wr itten t o a file f or fur ther use.These options ar e descr ibed in Prism M eshing Options f or Sc oped P risms (p.393). Problems r elated t o pr ism gener ation ar e discussed in Prism M eshing P roblems (p.395). 15.1. The P rism G ener ation P rocess The f ollowing pr ocess is used b y the mesher t o build the pr isms and t o cr eate a high-qualit y mesh. 367Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.1. Boundar y mesh analy sis: The initial sur face mesh is analyz ed t o det ermine if an y adjac ent zones should b e pr ojec ted t o ad- jacent zones and r etriangula ted (if tr iangular), or if their fac es should b e used as the sides of new prism c ells (if quadr ilateral). For details on det ermining whether t o use e xisting b oundar y zones or not , see Using A djac ent Zones as the S ides of P risms (p.386). 2. Prism la yer gr owth. Prism la yers ar e gr own one b y one , based on the la yer heigh t sp ecific ation. This is a multist ep procedur e, and henc e some of the st eps ma y be mo dified or sk ipped: a. Determine the initial dir ection v ectors so tha t the dir ection in which t o build the pr isms is det ermined . The dir ection metho ds a vailable ar e discussed in Direction Vectors (p.384). b.Check f or pr oximit y and det ermine shr inkage of pr ism la yers based on the pr oximit y options sp ecified . c.Determine the initial off set distanc es so tha t the mesher will k now ho w far fr om the c orresponding nodes on the pr evious la yer to plac e the new no des tha t define the pr isms . See Offset D istanc es (p.381) for details . d.Smooth the initial dir ection v ectors. See Normal S moothing (p.385) for details . e.Adjust and smo oth the off set distanc es to elimina te spik es and dips in the new pr ism la yer. See Offset Smoothing (p.383) for details f. Projec t new no des along the out er edges of the pr ism la yer to adjac ent zones , based on the analy sis in st ep 1. g.Create pr ism fac es and c ells using the new no des.The new fac es a t the t op of the pr ism la yer ar e referred t o as c ap fac es. h. The new c ap fac es of sk ewness v alue gr eater than the sp ecified thr eshold ar e impr oved b y edge swapping or edge no de smo othing . See Edge S wapping and S moothing (p.389) for details . i. Apply global smo othing acr oss the new sur face.This is also sk ewness-dr iven, but is based on the nodes not the fac es. See Node S moothing (p.390) for details . j. Check the qualit y of all new c ells and fac es. k. If qualit y pr oblems ar e det ected, prism la yer cr eation is st opp ed. If mor e layers ar e to be gr own, the process is r epeated star ting fr om subst ep (a). 3. Zone clean up: After all the pr ism la yers ha ve been gr own, the new fac es along the out er sides of the layers ar e mo ved t o zones of the same t ypes as the z ones t o which their no des ar e pr ojec ted. Unprojec ted faces ar e collec ted in a single prism-side zone . 4. Retriangula tion: Adjac ent triangular z ones tha t ha ve been pr ojec ted t o adjac ent zones ar e aut oma tically retriangula ted.Triangles tha t are overlapp ed b y new quadr ilateral fac es fr om the pr ism la yers ar e remo ved. Most of the or iginal no des ar e used in the new tr iangula tion. The r esult is a c onformal in terface between the sides of the pr ism la yers and the adjac ent triangular z ones . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 368Gener ating P risms15.1.1. Zones C reated D uring P rism G ener ation When pr isms ar e gener ated, several new c ell and fac e zones ar e created.You c an iden tify the new zones b y their default names . •The c ell z one c ontaining the pr isms will b e named prism-cells-# . •The fac e zone cr eated a t the end of the last pr ism la yer will b e named prism-cap-# . •If the pr ism la yers ar e bounded b y one or mor e existing tr iangular fac e zones , each of these will b e retrian- gula ted so tha t the fac es of the z one tha t are adjac ent to the pr isms will b ecome quadr ilateral fac es, while the r est of the fac es in the z one r emain tr iangles . If an or iginal tr iangular fac e zone is c alled symmetry , the p ortion of it tha t still c ontains tr iangles will b e retained as symmetry , while the p ortion c ontaining quadr ilateral fac es will b e named symmetry-quad:# . •Any fac es tha t were not pr ojec ted t o adjac ent zones (see Using A djac ent Zones as the S ides of P risms (p.386)) are collec ted in to a z one named prism-side-n . •For a z one wall-# , the z one cr eated b y ignor ing pr ism gr owth in the r egion of pr oximit y will b e named as wall-#:ignore , wher e,# is the z one numb er assigned . Imp ortant All the ignor ed thr eads r elated t o a base thr ead will b e mer ged in to a single thr ead b y default. You c an ho wever change this using the c ommand /mesh/prism/con- trols/merge-ignored-threads? which will gener ate mor e than one thr ead p er base thr ead. To mer ge one or mor e pr ism c ell z ones with other c ell z ones (and mer ge the c orresponding fac e zones), use the Merge option in the Manage C ell Z ones dialo g box. By default , the prism-cap-# zones will b e wall z ones . If you do not w ant to include these w alls in the mo del, change them t o in terior z ones (or an y other t ype) using the Manage F ace Zones dialo g box. Note If the pr ism mesh is gener ated using the Auto M esh tool and Merge C ell Z ones is enabled , the new fac e zones will b e mer ged with the or iginal b oundar y zones and a single c ell z one will b e created. 15.2. Procedur e for C reating Z one-based P risms The pr ocedur e for cr eating pr isms b y setting up z one-sp ecific par amet ers is as f ollows: 1. Check the b oundar y mesh t o ensur e tha t free no des or fac es with high sk ewness do not e xist. See Manip- ulating B oundar y Nodes (p.273) and Determining Sur face Mesh Q ualit y (p.492) for details . 369Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Procedur e for C reating Z one-based P risms2. Selec t the b oundar y zones fr om which y ou w ant to gr ow pr isms in the Boundar y Zones selec tion list in the Prisms dialo g box. Mesh → Prisms ... Alternatively, when using Auto M esh, selec t zone-sp ecific in the Grow P risms drop-do wn list and click Set... to op en the Prisms dialo g box. Imp ortant If you r ead in a mesh file cr eated in a pr evious v ersion, it is r ecommended tha t you r eset all the pr ism par amet ers using the c ommand /mesh/prism/reset-parameters before pr oceeding with setting the pr ism par amet ers. 3. Specify pr ism gr owth par amet ers in the Growth tab . a. Selec t the appr opriate Offset M etho d and Growth M etho d for gr owing pr isms . Figur e 15.2: Layer H eigh ts C omput ed U sing the F our G rowth M etho ds (p.371) sho ws layer heigh ts for all f our metho ds, using a first heigh t of 1 and a slop e/rate/exponen t of 1.2. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 370Gener ating P rismsFigur e 15.2: Layer H eigh ts C omput ed U sing the F our G rowth M etho ds See Offset D istanc es (p.381) for details . b.Define the heigh t of the first pr ism la yer (First H eigh t/First A spect Ratio). c.Set the gr owth metho d related par amet er (Slope,Rate, or Exponen t, as applic able) and the Numb er of L ayers. d.Specify options f or pr ism gr owth, proximit y det ection, and splitting of pr ism la yers (if needed) in the Prisms G rowth Options dialo g box (op ened using the Growth Options ... butt on), if requir ed. Refer to Prism M eshing Options f or Z one-S pecific P risms (p.373) for details . e.Click the Plot butt on t o pr eview the heigh t distr ibution. For inf ormation on setting diff erent growth par amet ers f or diff erent zones , see Growing P risms Simultaneously fr om M ultiple Z ones (p.374). 4. Specify the dir ection f or pr ism gr owth (see Direction Vectors (p.384)). a. Click the Direction tab in the Prisms dialo g box to view the dir ection par amet ers. 371Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Procedur e for C reating Z one-based P rismsb.Verify the or ientation of the nor mals f or the z ones on which y ou w ant to gr ow pr ism la yers. Ensur e that the nor mals ar e pointing in the dir ection tha t you w ant to build the pr isms . You c an use the Color b y Normal option, acc essible using the hotk ey Ctrl+Shift+C then Ctrl+N to verify the nor mal dir ection. •If the b oundar y zone nor mals ar e inc orrectly or iented, click the Orient Normals ... butt on t o op en the Orient Normals dialo g box. Specify the ma terial p oint based on which the nor mals ar e to be oriented and click Apply . •For mesh objec ts, use the options in the Orient Mesh O bjec t Face Normals group b ox to or ient the nor mals . a. Selec t the mesh objec t in the Objec t Name drop-do wn list. b.Selec t Region or Material P oint as appr opriate, and then selec t the r egion or ma terial p oint in the dr op-do wn list. c.Ensur e tha t Selec t is enabled , and enable Selec t Walls and/or Selec t Baffles as needed . d.Click Orient. Face boundar y zone gr oups c ompr ising the pr ism base z ones will b e created (pr efixed by _prisms ). c.Specify the metho d for det ermining the dir ection of the pr isms: •Selec t Normal in the Metho d list t o comput e nor mal dir ection v ectors.This metho d tak es in to accoun t the change in dir ection r equir ed f or a cur ved r egion. Specify the v alues f or the maximum angle change . •Selec t Uniform in the Metho d list t o use a c onstan t, unif orm dir ection f or fla t prism r egions . Specify the appr opriate dir ection v ector. 5. Set the par amet ers f or pr ism impr ovemen t and pr ism pr ojec tion a vailable in the Impr ove and Projec t tabs , respectively, as r equir ed. See Impr oving P rism M esh Q ualit y (p.389) or Using A djac ent Zones as the Sides of P risms (p.386) for mor e inf ormation. 6. Click Apply to sa ve your settings . 7. Save the mesh: File → Write → Mesh Imp ortant It is a go od pr actice to sa ve the mesh a t this p oint. If you ar e dissa tisfied with the pr isms gener ated, you c an r ead in this mesh and mo dify the pr ism par amet ers t o regener ate the pr isms . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 372Gener ating P risms8. Click Create to gener ate only the pr ism c ell z one . Refer to Prism M eshing P roblems (p.395) for suggestions on solving pr oblems o ccur ring dur ing prism gener ation. Alternatively, when using Auto M esh, click Apply and close the Prisms dialo g box.The pr ism c ells will b e created first , and then the mesher will pr oceed t o gener ating the t et/he xcore mesh. Refer to Using the A uto M esh D ialog Box (p.349) for details . 9. Check the maximum fac e sk ewness v alue r eported in the c onsole when the final pr ism la yer is cr eated, to ensur e tha t the v alue is acc eptable . This is esp ecially imp ortant if y ou ar e going t o gener ate tetrahedr al or p yramidal c ells using this new b oundar y zone . The new z one should not ha ve highly sk ewed tr iangles or quadr ilaterals. For mor e inf ormation about the qualit y of quadr ilateral fac es used f or cr eating p yramids , refer to Creating P yramids (p.353). If the r eported maximum sk ewness is t oo high, read the mesh file y ou sa ved af ter setting the pr ism paramet ers and tr y again with diff erent par amet ers. Refer to Prism M eshing P roblems (p.395) for details . 10. A numb er of new z ones ar e created when the pr ism gener ation is c omplet e (see Zones C reated D uring Prism G ener ation (p.369)). If the pr ism-c ap or pr ism-side fac e zones ar e not supp osed t o be walls (f or e x- ample , if the y are supp osed t o be simple in terior z ones), change them t o the appr opriate boundar y type. Boundar y → Manage For most c ases , performing these st eps will r esult in an acc eptable mesh of pr isma tic c ells, but f or some comple x geometr ies, you ma y ha ve to mo dify the pr ocedur e. If you ar e not sa tisfied with the pr isms gener ated, you c an r ead in the mesh y ou sa ved b efore gener ating pr isms and mo dify the pr ism par a- met ers. Refer to subsequen t sec tions f or details on mo difying the pr ism gener ation par amet ers t o cr eate a better mesh. The pr ocedur e for using z one-sp ecific pr ism c ontrols f or cr eating pr isms dur ing v olume meshing using Auto M esh is descr ibed in Using the A uto M esh D ialog Box (p.349). 15.3. Prism M eshing Options f or Z one-S pecific P risms This sec tion descr ibes the pr ism meshing options a vailable f or cr eating a pr ism mesh based on z one- specific settings . 15.3.1. Growth Options f or Z one-S pecific P risms 15.3.2. Offset D istanc es 15.3.3. Direction Vectors 15.3.4. Using A djac ent Zones as the S ides of P risms 15.3.5. Impr oving P rism M esh Q ualit y 15.3.6. Post P rism M esh Q ualit y Impr ovemen t 15.3.1. Growth Options f or Z one-S pecific P risms This sec tion descr ibes the additional gr owth options a vailable f or cr eating a pr ism mesh based on zone-sp ecific settings . 15.3.1.1. Growing P risms S imultaneously fr om M ultiple Z ones 373Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Prism M eshing Options f or Z one-S pecific P risms15.3.1.2. Growing P risms on a Two-Sided Wall 15.3.1.3. Ignor ing In valid N ormals 15.3.1.4. Detecting P roximit y and C ollision 15.3.1.5. Splitting P rism La yers 15.3.1.6. Preser ving Or thogonalit y 15.3.1.1. Growing P risms S imultaneousl y from Multiple Z ones You c an selec t multiple fac e zones f or simultaneously gr owing pr ism la yers. If the fac e zones ar e connec ted, the pr isms gr own will also b e connec ted. A single z one of pr ism c ells and a single z one of c ap fac es will b e created f or each set of simultaneously gr own la yers.To retain the individual pr ism cell z ones and c ap fac e zones , enable Grow Individually in the Prisms G rowth Options dialo g box (opened b y click ing the Growth Options ... butt on). You c an gr ow pr isms fr om multiple z ones with the same or diff erent growth par amet ers. •To use the same gr owth par amet ers f or all z ones , follow the st eps in Procedur e for C reating Z one-based Prisms (p.369). In this c ase, the same numb er of la yers ar e gr own fr om all z ones , and all other par amet ers (growth metho d, offset metho d, direction metho d, and so on) also r emain the same . •To use diff erent growth par amet ers f or diff erent zones , you c an apply diff erent growth metho ds, offset metho ds, first heigh t, and other gr owth par amet ers (as r equir ed f or the gr owth metho d selec ted) individu- ally f or each z one and click the Apply butt on in the Zone S pecific G rowth group b ox in the Prisms dialo g box. If you sp ecify diff erent growth par amet ers f or diff erent zones , all other par amet ers (dir ection metho d, offset metho d, and so on) c an b e set separ ately f or each z one . In this c ase, the off set heigh t of each no de tha t is shar ed b y multiple z ones will b e the a verage of the heigh ts applied on the separ ate zones . This pr oduces a c ontinuous tr ansition b etween the z ones ( Figur e 15.3: Different Growth P aramet ers on A djac ent Zones (p.374)). Offset smo othing (see Offset S moothing (p.383)) is r ecommended in these c ases t o avoid shar p heigh t changes a t such edges . Figur e 15.3: Different Growth P aramet ers on A djac ent Zones To assign diff erent growth c ontrols and diff erent off set t ypes to diff erent fac e zones , replac e steps 2 and 3 in Procedur e for C reating Z one-based P risms (p.369) with the f ollowing st eps: 1. Selec t the z ones f or which y ou w ant to sp ecify a set of gr owth par amet ers in the Boundar y Zones list in the Prisms dialo g box. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 374Gener ating P risms2. Set the appr opriate Offset M etho d,Growth M etho d,First H eigh t, and the r elated gr owth par amet ers (as r equir ed) in the Growth tab . 3. Specify par amet ers f or pr oximit y/collision det ection in the Prisms G rowth Options dialo g box (see Detecting P roximit y and C ollision (p.378) for details). Imp ortant By default , a single z one of pr ism c ells and c ap fac es is gener ated f or the simultan- eously gr own pr ism la yers. If you w ant to retain individual pr ism c ell z ones and c ap faces, enable Grow Individually in the Gener al Options group b ox in the Prisms Growth Options dialo g box. 4. Click Apply in the Prisms dialo g box. 5. Repeat this pr ocedur e for other z ones f or which y ou w ant to apply diff erent growth c ontrols. 6. Click Create. Warning Before you click the Create butt on, ensur e tha t all the z ones f or which y ou w ant to gr ow pr isms ar e selec ted in the Boundar y Zones list. Note When the Prisms dialo g box is used t o gener ate pr ism la yers on multiple z ones (adjac ent or nonadjac ent), the numb er of la yers is det ermined b y the chr onolo gically last selec ted z one in the Boundar y Zones selec tion list. Imp ortant –If you sp ecify diff erent numb er of la yers t o be gr own on adjac ent zones , the same numb er of la yers (gener ally the smaller numb er of la yers) will b e gr own on b oth the zones (see Figur e 15.3: Different Growth P aramet ers on A djac ent Zones (p.374)). –If you sp ecify diff erent numb er of la yers on multiple (nonadjac ent) zones and use the Prisms dialo g box to gener ate the pr ism la yers, the same numb er of la yers will b e gr own on the r espective zones .The numb er of la yers is det ermined b y the chr onolo gically last selec ted z one in the Boundar y Zones selec tion list. –If you sp ecify diff erent numb er of la yers on multiple (nonadjac ent) zones and use the Auto M esh dialo g box to gener ate the pr ism la yers, the pr ism la yers will b e gr own separ ately fr om each z one: 375Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Prism M eshing Options f or Z one-S pecific P rismsFigur e 15.4: Different Growth P aramet ers on N onadjac ent Zones—U sing the Auto M esh Option 15.3.1.2. Growing P risms on a Two-S ided Wall Two-sided w alls ma y be pr esen t in some mo dels .To gr ow pr isms on b oth sides of a t wo-sided w all (for e xample , growing pr isms on dangling w alls), do the f ollowing: 1. Selec t the t wo-sided w all on which y ou w ant to gr ow pr isms fr om the Boundar y Zones selec tion list. 2. Specify the pr ism gr owth par amet ers as r equir ed. 3. Enable Grow on Two Sided Wall in the Growth tab of the Prisms dialo g box. 4. Click Create.Figur e 15.5: Prism G rowth on a D angling Wall (p.377) sho ws an e xample of pr isms gr own on a dangling w all. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 376Gener ating P rismsFigur e 15.5: Prism G rowth on a D angling Wall 15.3.1.3. Ignoring In valid N ormals Some mo dels ma y contain r egions wher e the nor mals c onsider ed while gr owing pr isms ma y be invalid. The nor mal a t a par ticular no de ma y be near ly tangen tial t o the sur rounding fac es in the mo del and as a r esult , the pr ism gener ation ma y fail. For such c ases , you c an cho ose t o ignor e regions of the model wher e invalid nor mals e xist, dur ing pr ism gener ation. Prism la yers will b e gr own fr om the r e- maining r egions acc ording t o the sp ecified par amet ers. Figur e 15.6: Ignor ing In valid N ormals (p.377) sho ws a p ortion of the mo del wher e the nor mal a t the highligh ted no de will b e near ly tangen tial t o some of the sur rounding fac es.You c an see tha t the region ar ound this no de has b een ignor ed while cr eating pr isms . Figur e 15.6: Ignor ing In valid N ormals You c an ignor e regions based on nor mals while cr eating pr isms as f ollows: 1. Specify the pr ism gr owth par amet ers. 377Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Prism M eshing Options f or Z one-S pecific P risms2. Selec t the Boundar y Zone containing the in valid nor mal and click the Growth Options ... butt on t o open the Prisms G rowth Options dialo g box. a. Enable Ignor e In valid N ormals in the Gener al Options group b ox. b.Click Apply and close the Prism G rowth Options dialo g box. 3. Grow pr isms as r equir ed. 15.3.1.4. Detecting P roximit y and C ollision If the z ones on which y ou w ant to gr ow pr isms ar e very close t o each other , the pr ism la yers fr om zones ma y intersec t or c ollide with each other .This r esults in bad qualit y of pr ism la yers. For e xample , in Figur e 15.7: Collision of P rism La yers (p.378), the pr ism la yers gr own fr om pr oximal surfaces in tersec t each other .The Allow S hrinkage option allo ws you t o avoid the in tersec tion of prism la yers b y adjusting the heigh t of the pr ism la yers in closely plac ed z ones .Figur e 15.8: Prism Layers S hrunk t o Avoid C ollision (p.379) sho ws the use of this option t o avoid in tersec tion of the prism la yers b y adjusting the pr ism la yer heigh t. Figur e 15.7: Collision of P rism L ayers Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 378Gener ating P rismsFigur e 15.8: Prism L ayers S hrunk t o Avoid C ollision A value of n for Gap F actor implies tha t a gap equal t o n times the maximum base edge length a t the no de in question will b e main tained . Hence, a value of 1 implies tha t the gap main tained is equal to the maximum base edge length a t the no de c onsider ed. Imp ortant Offset heigh ts ar e sc aled only in the r egions wher e the in tersec tion of pr ism la yers tak es plac e. For the r emaining r egions , the pr isms ar e created acc ording t o the sp ecified par a- met ers. You c an also ignor e pr isms in r egions of close pr oximit y dur ing pr ism gener ation. The ar ea of pr oximit y will b e det ermined based on the shr ink fac tor sp ecified . Prism la yers will b e gr own fr om the r emaining regions acc ording t o the sp ecified par amet ers. Figur e 15.9: Ignor ing A reas of P roximit y (p.380) sho ws a p ortion of the mo del wher e the r egion of proximit y in a shar p corner has b een ignor ed while cr eating pr isms . 379Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Prism M eshing Options f or Z one-S pecific P rismsFigur e 15.9: Ignor ing A reas of P roximit y For aut oma tic adjustmen t of in tersec ting/c olliding pr ism la yers while gr owing pr isms , do the f ollowing: 1. Specify the pr ism gr owth par amet ers. 2. Click Growth Options ... in the Growth tab t o op en the Prisms G rowth Options dialo g box. 3. Enable the appr opriate options in the Gener al Options group b ox. 4. Specify the par amet ers r equir ed f or the pr oximit y calcula tion and c ontrolling the pr ism la yer heigh t. a. Enable Allow S hrinkage to allo w shr inkage of pr ism la yers in ar eas of pr oximit y.This option is enabled b y default. b.Enable Keep F irst L ayer O ffsets , if requir ed. This option allo ws you t o keep the or iginal first off set heigh t and sc ale the off set heigh ts for the r emaining la yers in c ase of in tersec ting pr ism la yers. c.Specify an appr opriate value f or Gap F actor. d.Enable Allow Ignor e to ignor e the pr ism gr owth par amet ers in ar eas of pr oximit y. e.Enter an appr opriate value f or Max A spect Ratio or Max S hrink F actor as r equir ed. f. Click Apply and close the Prism G rowth Options dialo g box. 5. Click Create in the Prisms dialo g box. 15.3.1.5. Splitting P rism L ayers You c an gener ate fewer pr ism la yers and then split them as par t of the pr ism gener ation pr ocess t o gener ate the t otal numb er of pr ism la yers r equir ed.This option is fast er than gener ating the same total numb er of pr ism la yers. You c an sp ecify the numb er of divisions p er pr ism la yer as f ollows: 1. Specify the pr ism gr owth par amet ers. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 380Gener ating P risms2. Click Growth Options ... to op en the Prisms G rowth Options dialo g box. 3. Enable Split in the Split Options group b ox. 4. Specify the Divisions P er L ayer. 5. Click Apply and close the Prism G rowth Options dialo g box. 15.3.1.6. Preser ving O rtho gonalit y In some c ases , it ma y be imp ortant for the pr isma tic mesh t o be or thogonal near the or iginal boundar y. For such c ases , ther e ar e two ways to pr eser ve or thogonalit y: •Decrease the v alue sp ecified f or the Max. Angle C hange in the Direction tab of the Prisms dialo g box to a lo wer value t o limit the change in nor mal dir ection in each pr ism la yer. This par amet er is set t o 60 degr ees b y default. This means the nor mal dir ection a t a no de c an change up t o 60 degr ees dur ing nor mal, edge , and no de smo othing . For e xample , if y ou r educ e this par amet er to 10 degr ees, the change in nor mal dir ection will b e mor e gr adual, and the mesh near the or iginal b oundar y will b e near ly or thogonal. •Specify an e xplicit numb er for Ortho gonal L ayers in the Direction tab of the Prisms dialo g box. When y ou sp ecify or thogonal la yers, you should decr ease the Max A ngle C hange to appr oxima tely 10 degr ees.This will pr event sudden shar p changes in nor mal dir ection a t the first non-or thogonal layer. For a non-or thogonal la yer, edge sw apping , nor mal, edge , or no de smo othing will b e performed so tha t the la yer is or thogonal t o the or iginal b oundar y. For e xample , if y ou sp ecify 5 or thogonal layers, no smo othing will b e performed on the first 5 la yers, resulting in dir ection v ectors tha t are normal t o the or iginal sur face mesh fac es. Full smo othing is used on the six th and subsequen t layers. Imp ortant If you ar e pr eser ving or thogonalit y near the or iginal b oundar y, mak e sur e tha t the pr ism layers do not gr ow too quick ly. Use small la yer heigh ts, relative to the siz es of the fac es on the or iginal b oundar y. If prism la yers gr ow quick ly, the near ly-or thogonal dir ection vectors ar e lik ely t o cr oss a t shar p concave corners , causing the pr ism gener ation t o fail. The pr ism la yer gener ation will b e stopp ed a t this p oint. See Normal S moothing (p.385). Preser ving or thogonalit y can aff ect skewness and lead t o lef t-handed fac es and/or nega tive volumes . See Negative Volumes/L eft-Handed F aces/High S kewness (p.396) for details . 15.3.2. Offset D istanc es The off set distanc e for a giv en no de is the distanc e between adjac ent layers a t tha t no de.This distanc e is based on the pr ism la yer heigh t comput ed fr om the sp ecified pr ism gr owth par amet ers.The new node f or a pr ism la yer is plac ed a t this distanc e along the dir ection v ector. There ar e four metho ds a vailable f or det ermining the off set distanc es: 381Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Prism M eshing Options f or Z one-S pecific P risms•Uniform O ffset D istanc e M etho d: In this metho d, every new no de (child) is initially the same distanc e away from its par ent no de (tha t is, the c orresponding no de on the pr evious la yer, from which the dir ection vector is p ointing). Figur e 15.10: Uniform O ffset D istanc e M etho d Uniform distanc es ar e fine f or planar sur face meshes , but the y result in cr evices a t shar p corners , for e xample , the 90 degr ee c orner in Figur e 15.10: Uniform O ffset D istanc e M etho d (p.382).The dir- ection v ector a t the c orner no de will b e at an angle of 45 degr ees, while the v ectors a t the adjac ent nodes will b e sligh tly mor e or thogonal t o their fac es. For unif orm distanc es, this plac es the no des for the first la yer as sho wn in Figur e 15.10: Uniform O ffset D istanc e M etho d (p.382). The dashed line c onnec ting the new no des b egins t o pinch inw ard at the c orner.The distanc es between par ent and child no des ar e still all the same , but the angles of the dir ection v ectors in troduce this pinching eff ect.Without some sor t of c orrection such cr evices c an e ventually c ollapse . •Minimum H eigh t Offset D istanc e M etho d: In this metho d, child no des ar e guar anteed t o be at least as far fr om their par ent no des as the distanc e comput ed f or the cur rent layer fr om the gr owth inputs .The mesher will also tr y to retain the shap e of the or iginal b oundar y. Figur e 15.11: Minimum-H eigh t Offset D istanc e M etho d For a p erfect 90 degr ee c orner, this r esults in a p erfect 90 degr ee c orner f or the ne xt layer (see Fig- ure 15.11: Minimum-H eigh t Offset D istanc e M etho d (p.382)).Thus, in this metho d the shap e is b etter preser ved if no additional smo othing is applied . The minimum heigh t metho d ha ve some limita tions . If the angle of the dir ection v ector a t the c orner is not 45 degr ees (tha t is, if it do es not e xactly bisec t the angle b etween the fac es), the minimum- heigh t metho d can incr ease sk ewness . •Aspect Ratio M etho d:This metho d allo ws you t o control the asp ect ratio of the pr ism c ells tha t are extruded from the base b oundar y zone .The asp ect ratio is defined as the r atio of the pr ism base length t o the pr ism layer heigh t.The v arious gr owth metho ds (c onstan t, linear , geometr ic, and e xponen tial) c an b e used t o specify the asp ect ratio of the first la yer. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 382Gener ating P rismsWhen a non-c onstan t growth metho d is used , the asp ect ratio f or subsequen t layers will change accordingly .The heigh ts of the pr ism c ells will v ary acc ording t o the lo cal fac e siz es in the sur face mesh, providing a c onvenien t way to aut oma tically v ary pr ism heigh ts acr oss a z one . •Last R atio M etho d:This metho d also allo ws you t o control the asp ect ratio of the pr ism c ells tha t are ex- truded fr om the base b oundar y zone .You c an sp ecify First H eigh t for the first pr ism la yer. If you selec t this metho d, the v arious gr owth metho ds will not b e acc essible .The last asp ect ratio metho d is e xplained in Figur e 15.12: Last R atio M etho d (p.383). Figur e 15.12: Last R atio M etho d Local base mesh siz e is used t o find out the off set heigh t for the last la yer. For e xample , if y ou sp ecify 80 as the Last P ercent value the off set heigh t of the last la yer will b e 0.8 times the lo cal base mesh size. Local gr owth r ate is used t o calcula te the other in termedia te off set heigh ts exponen tially . Note Onc e calcula ted, the ac tual last last la yer off set heigh t is not adjust ed in c ases of concave or c onvex base , or non-or thogonal la yers. Offset Smo othing The pur pose of off set smo othing is t o elimina te spik es and dips in the new sur face layer. Smoothing is applied it eratively.Figur e 15.13: Effect of O ffset S moothing (p.384) sho ws ho w the no des ar e mo ved during off set smo othing . 383Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Prism M eshing Options f or Z one-S pecific P rismsFigur e 15.13: Effect of O ffset S moothing 15.3.3. Direction Vectors As each la yer of pr isms is built , the mesher needs t o know the dir ection in which t o build .There ar e two metho ds a vailable f or det ermining the dir ection v ectors: •Extrusion M etho d: For cr eating str aigh t-sided pr ism r egions without an y cur vature, you c an sp ecify a unif orm dir ection v ector for all pr ism la yers. Selec t Uniform in the Metho d list in the Direction tab of the Prisms dialo g box. Figur e 15.14: Uniform D irection Vector f or a S traigh t-Sided P rism Region Specify the unif orm dir ection v ector or click Comput e in the Vector group b ox.This c onstan t vector will b e used f or all pr ism la yers, inst ead of c omputing a new dir ection f or each la yer (see Fig- ure 15.14: Uniform D irection Vector for a S traigh t-Sided P rism R egion (p.384)). Note The Grow On Two Sided Wall option c annot b e used when the Uniform metho d is se- lected. •Normal M etho d: For regions with cur vature, the appr opriate nor mal dir ection v ector a t each no de will b e determined b ecause it ma y be diff erent for each no de and each la yer. See Figur e 15.15: Normal D irection Vectors f or a C urved P rism R egion (p.385). Selec t Normal in the Metho d group b ox in the Direct tab of the Prisms dialo g box. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 384Gener ating P rismsFigur e 15.15: Normal D irection Vectors f or a C urved P rism Region Normal Smo othing The nor mal dir ection v ectors obtained using the metho ds descr ibed in Direction Vectors (p.384) are smo othed so tha t ther e is a gr adual change in dir ection fr om one no de t o the ne xt.This will r educ e the chanc e of dir ection v ector in tersec tion, which c auses the pr ism gener ation t o fail. This st ep is not necessar y when a unif orm dir ection v ector is used b ecause ther e is no change in dir ection fr om one node t o the ne xt. Figur e 15.16: Normal D irection Vectors B efore Smoothing (p.385) sho ws nor mal dir ection v ectors in the vicinit y of a shar p (90 degr ee) c orner. Figur e 15.16: Normal D irection Vectors B efore Smoothing The dir ection v ector is a t an angle of 45 degr ee a t the c orner, while elsewher e it is 0 or 90 degr ees. These dir ection v ectors will in tersec t and pr isms c annot b e gener ated.Figur e 15.17: Normal D irection Vectors A fter S moothing (p.386) sho ws the nor mal dir ection v ectors near the c orner af ter the y ha ve been smo othed . After smo othing , the nor mal dir ection changes mor e gr adually fr om no de t o no de. 385Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Prism M eshing Options f or Z one-S pecific P rismsFigur e 15.17: Normal D irection Vectors A fter S moothing It is p ossible t o cr eate very thin pr ism la yers using the dir ection v ectors sho wn in Figur e 15.16: Normal Direction Vectors B efore Smoothing (p.385), as long as the last la yer lies b elow the p oint wher e the vectors cr oss. 15.3.4. Using A djac ent Zones as the S ides of P risms For each z one adjac ent to the z ones fr om which y ou gr ow pr isms , the angle b etween the pr ism gr owth direction and the adjac ent zone will b e check ed. Depending on the siz e of this angle , the mesher will decide whether t o use the adjac ent zone f or the pr ism sides , or cr eate a new z one . Using A djac ent Q uadrilat eral F ace Zones An adjac ent zone with quadr ilateral fac es will b e used without mo dific ation as the pr ism-side b oundar y if it sa tisfies the f ollowing r equir emen ts: •It must shar e no des with the b oundar y zone fr om which y ou ar e building the pr isms tha t is, ther e must b e no fr ee no des (see Free and I sola ted N odes (p.273)) wher e the z ones t ouch. •The angle b etween the adjac ent zone and the pr ism gr owth dir ection must b e less than the sp ecified threshold ,Max. Adjac ent Zone A ngle (in the Projec t tab of the Prisms dialo g box).The default thr eshold value is 75 degr ees. For e xample , if y ou ar e gr owing pr isms fr om the b ottom sur face in Figur e 15.18: Effect of A djac ent Zone A ngle (p.387) using the default maximum adjac ent zone angle of 75 degr ees, the z one on the left will b e excluded , but the z one on the r ight will b e used as it is . A new z one will b e created f or the left sides of the pr isms . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 386Gener ating P rismsFigur e 15.18: Effect of A djac ent Zone A ngle To fill in the gap on the lef t side of Figur e 15.18: Effect of A djac ent Zone A ngle (p.387), create pyramids using the pr ism side fac es, create a domain, and gener ate tetrahedr al cells. Projec ting t o Adjac ent Triangular F ace Zones If an adjac ent zone has tr iangular fac es, two additional st eps will b e performed t o inc orporate the zone in to the pr ism la yers: projec tion and r etriangula tion. The mesher will pr ojec t the out er no des of the pr isms on to the tr iangular fac es of the adjac ent zone , provided it sa tisfies the f ollowing r equir emen ts: •It must shar e no des with the b oundar y zone fr om which y ou ar e building the pr isms .That is, ther e must b e no fr ee no des (see Free and I sola ted N odes (p.273)) wher e the z ones t ouch. •The angle b etween the adjac ent zone and the pr ism gr owth dir ection must b e less than the sp ecified threshold ,Max. Adjac ent Zone A ngle (in the Projec t tab of the Prisms dialo g box).The default threshold v alue is 75 degr ees. In Figur e 15.18: Effect of A djac ent Zone A ngle (p.387), the z one on the r ight will b e pr ojec ted t o and retriangula ted, while the z one on the lef t will b e excluded . Retriangulation As sho wn in Figur e 15.1: Prism S hap es (p.367), the sides of the pr ism will alw ays be quadr ilateral fac es, regar dless of the t ype of fac e from which the pr ism is built (tr iangular or quadr ilateral). If the pr ism- side no des ar e pr ojec ted t o an adjac ent triangular b oundar y fac e zone: 1. The pr ism-side fac es on the shar ed b oundar y will b e overlaid on the tr iangular fac es of the e xisting boundar y zone . 2. The tr iangular b oundar y zone will b e retriangula ted so tha t the tr iangular p ortion of the z one ends a t the b order of the p ortion no w filled with quadr ilateral fac es.This is done t o obtain a c onformal mesh wher e all the no des ma tch up a t fac e edges . 3. The tr iangles tha t were overlapping the quadr ilateral pr ism-side fac es will b e delet ed. Figur e 15.19: Symmetr y Zone and C ar Wall B efore Prism G ener ation (p.388) sho ws the initial b oundar y mesh f or a c ar and the symmetr y boundar y beside it. If the pr isms ar e gener ated fr om the c ar b ody without retriangula tion of the tr iangular symmetr y boundar y, the r esulting b oundar y mesh will b e as shown in Figur e 15.20: Symmetr y Zone and C ar Wall A fter P rism G ener ation Without R etriangula- tion (p.388).With r etriangula tion, the b oundar y mesh will app ear as in Figur e 15.21: Symmetr y Zone and C ar Wall A fter P rism G ener ation and R etriangula tion (p.389). 387Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Prism M eshing Options f or Z one-S pecific P rismsFigur e 15.19: Symmetr y Zone and C ar Wall B efore Prism G ener ation Figur e 15.20: Symmetr y Zone and C ar Wall A fter P rism G ener ation Without Retr iangula tion Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 388Gener ating P rismsFigur e 15.21: Symmetr y Zone and C ar Wall A fter P rism G ener ation and Retr iangula tion Imp ortant Though it is p ossible t o disable r etriangula tion (b y disabling the Retr iangula te Adjac ent Zones option in the Projec t tab of the Prisms dialo g box), it is not alw ays recommended . Expert users e xperimen ting with diff erent settings ma y temp orarily disable r etriangula tion. 15.3.5. Impr oving P rism M esh Q ualit y You c an cho ose t o impr ove pr ism mesh qualit y by sw apping or smo othing edges , and smo othing nodes.These options ar e swit ched off b y default. 15.3.5.1. Edge S wapping and S moothing 15.3.5.2. Node S moothing 15.3.5.1. Edge S wapping and Smo othing You c an cho ose t o impr ove pr ism mesh qualit y by sw apping or smo othing edges . After the new c ap faces ar e created f or the new la yer, the sk ewness is c ompar ed with the sp ecified sk ewness thr eshold (Skewness in the Swapping and S moothing group b ox in the Impr ove tab of the Prisms dialo g box). If the sk ewness of a fac e is t oo high, the f ollowing impr ovemen t procedur e is c arried out: 1. Swap the longest edges of highly sk ewed fac es. When edge sw apping o ccurs on a c ap fac e, swapping pr opaga tes do wnw ard. Swapping must be performed on the c orresponding fac es on all pr ism la yers, including the fac e on the or iginal boundar y mesh, so tha t the gr id lines within the pr ism la yers do not cr oss. Imp ortant Swapping is not performed if it will signific antly alt er the geometr y defined b y the original b oundar y mesh. 389Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Prism M eshing Options f or Z one-S pecific P risms2. If sw apping is not p erformed , the sk ewness will b e impr oved b y smo othing the no des of the sk ewed faces using one of the f ollowing op erations . •If the shar pest angle a t the no de (tha t is, the most acut e angle b etween adjac ent fac es tha t use the node) is near ly 180 degr ees, smo othing will b e performed (as descr ibed in Node S moothing (p.390)) to mo ve the no des. •If the shar pest angle is far fr om 180 degr ees, the smo othing will b e limit ed so tha t the no des ar e only allowed t o mo ve along the fac e’s longest edge .This metho d will pr event the c ollapse of shar p corners in the mesh. Note Smoothing do es not propaga te do wnw ard, it is p erformed only on the sk ewed c ap faces themselv es. Imp ortant This edge sw apping/smo othing pr ocedur e is not p erformed on quadr ilateral cap fac es. 15.3.5.2. Node Smo othing If the edge sw apping and smo othing ar e not sufficien t to reduc e the sk ewness of some fac es, you can include an additional smo othing op eration. In this metho d, if an y of the fac es sur rounding a new node ha ve a sk ewness gr eater than the sp ecified thr eshold , the no de is smo othed . Instead of mo ving only the no de, this metho d will also mo ve the sur rounding no des t o mak e spac e for the no de t o mo ve. Figur e 15.22: Node S moothing in R ings The sur rounding no des ar e gr oup ed and smo othed in r ings (see Figur e 15.22: Node S moothing in Rings (p.390)).The no des on the out ermost r ing ar e smo othed first , and so on, until the tar get no de (on r ing z ero) is finally smo othed . This t ype of smo othing is helpful in c oncave ar eas wher e the ad vancing la yers c ontinually decr ease the a vailable sur face ar ea, causing squashing of tr iangular fac es. By smo othing out er rings of no des first , mor e spac e is pr ovided f or the no des tha t need t o be mo ved in or der t o reduc e the sk ewness . Thus, this metho d performs r egional smo othing ar ound fac es of high sk ewness .The no de smo othing procedur e can b e performed on b oth tr i and quad fac es. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 390Gener ating P risms15.3.6. Post P rism M esh Q ualit y Impr ovemen t You c an impr ove pr ism c ell qualit y in a p ostpr ocessing st ep af ter all the r equir ed pr ism la yers ar e created.The f ollowing options ar e available: 15.3.6.1. Impr oving the P rism C ell Q ualit y 15.3.6.2. Remo ving P oor Q ualit y Cells 15.3.6.3. Impr oving Warp 15.3.6.1. Impr oving the P rism C ell Q ualit y The Prism Impr ove dialo g box contains options tha t allo w you t o impr ove the pr ism c ell qualit y based on the qualit y measur e selec ted.The qualit y measur es a vailable ar e ICEM CFD qualit y, orthosk ew, skewness , or squish. The f ollowing options ar e available: •The Smooth option allo ws optimiza tion based smo othing of pr ism c ells. Poor qualit y cells c an b e iden tified based on the qualit y measur e selec ted.The no des of c ells with qualit y worse than the sp ecified Max C ell Qualit y value will b e mo ved t o impr ove qualit y.The c ell asp ect ratio will also b e main tained based on the v alue sp ecified f or max-aspect-ratio . •The Impr ove option c ollec ts and smo oths c ells in la yers ar ound p oor qualit y cells. Poor qualit y cells c an be iden tified based on the qualit y measur e selec ted. Cells with qualit y worse than the sp ecified Max C ell Qualit y value will b e iden tified , and the no des of the c ells sur rounding the p oor qualit y cells will b e mo ved to impr ove qualit y.The c ell asp ect ratio will also b e main tained based on the v alue sp ecified f or max- aspect-ratio . •The Smooth and Impr ove option uses a c ombina tion of no de mo vemen t and optimiz ed smo othing t o impr ove the qualit y.This option is a c ombina tion of the Smooth and Impr ove options .The c ell asp ect ratio will also b e main tained based on the v alue sp ecified f or max-aspect-ratio . When the Smooth and Impr ove option is enabled in the Post Op erations group b ox in the Impr ove tab of the Prisms dialo g box, the pr ism c ells will b e impr oved based on the options selec ted in the Prism Impr ove dialo g box, after the r equir ed pr ism la yers ar e created. You c an alt ernatively use the options in the Prism Impr ove dialo g box to impr ove the pr ism c ell qualit y in a p ostpr ocessing st ep af ter the mesh is cr eated. Mesh → Tools → Prism → Impr ove 15.3.6.2. Remo ving P oor Q ualit y Cells In cases wher e the pr ism mesh is cr eated separ ately (without using the Merge C ell Z ones option in the Auto M esh tool) and the prism-c ap zone e xists , you c an use additional options t o remo ve layers of p oor qualit y cells in r egions of p oor qualit y and shar p corners . •The Prism P ost Ignor e dialo g box contains options tha t allo w you t o remo ve poor qualit y pr ism c ells based on qualit y, intersec tion, interior w arp, and f eature edges .You c an sp ecify the numb er of c ell rings to be remo ved ar ound the mar ked c ells. Cells will b e mar ked f or remo val in r egions of shar p corners based on the Ignor e Options selec ted and then e xtended based on the numb er of c ell rings sp ecified . Additional cells will b e mar ked f or remo val in r egions of high asp ect ratio and f eature angle (if selec ted in the Expand Ignor e Options group b ox) ar ound the e xposed pr ism side . The Feature Edges tab c ontains options f or manipula ting f eature edges t o be used f or the p ost- ignor e op eration. You c an e xtract edge z ones fr om the pr ism base z ones when the pr ism c ap z one 391Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Prism M eshing Options f or Z one-S pecific P rismsis selec ted in the Boundar y Zones list. The edge z ones ar e extracted based on the Feature Angle specified . Other op erations lik e mer ging or separ ating the edge z ones ar e also a vailable . The b oundar y will b e smo othed a t feature corners af ter the pr ism c ells ha ve been r emo ved.The prism-side fac es e xposed b y the r emo val of the pr ism c ells will b e collec ted in a z one named prism-side-# , while f or a z one wall-# , the fac es c orresponding t o the ignor ed pr ism c ells will be collec ted in a z one named wall-#:ignore .You c an also optionally smo oth the pr ism side nodes fr om the base no de t o the c ap no de t o cr eate better tr iangles f or the non-c onformal in terface. When the Ignor e option is enabled in the Post Op erations group b ox on the Impr ove tab of the Prisms dialo g box, the pr ism c ells will b e remo ved based on the options selec ted in the Prism Post Ignor e dialo g box, after the r equir ed pr ism la yers ar e created. Note The Feature Edge option, under Ignor e Options in the Prism P ost Ignor e dialo g box, requir es a pr ism-c ap z one t o be pr esen t so it c annot b e used as a Post Op er- ation control dur ing pr ism gener ation. You c an alt ernatively use the options in the Prism P ost Ignor e dialo g box to remo ve layers of p oor qualit y cells in a p ostpr ocessing st ep af ter the mesh is cr eated. Mesh → Tools → Prism → Post Ignor e •The Prism Tet Impr ove Cavity dialo g box contains options f or cr eating a c avity in r egions wher e the prism qualit y is adequa te, but the qualit y of adjac ent tetrahedr a is p oor.The c avity is cr eated based on the t etrahedr al cell z one , the qualit y measur e and the c orresponding thr eshold v alue sp ecified . Additional cells will b e remo ved based on the numb er of e xpand c ell rings sp ecified .You c an cr eate a c avity compr ising only t etrahedr al cells or optionally include pr ism c ells when the c avity is cr eated.When pr ism c ells ar e also included in the c avity, you c an sp ecify whether the non-c onformal in terface is t o be created. Mesh → Tools → Prism → Tet Impr ove Cavity 15.3.6.3. Impr oving Warp Impr oving w arp in pr isms is a p ostpr ocessing st ep which is c arried out af ter all the r equir ed pr ism layers ar e created.The fac e warp in the gener ated pr ism fac es is impr oved b y mo ving the no des of the fac e to mak e it planar . When the Impr ove Warp option is enabled in the Post Op erations group b ox in the Impr ove tab of the Prisms dialo g box, the pr ism la yers ha ving fac es with w arp ≥ 0.5 ar e iden tified . The no des on the iden tified fac es ar e mo ved and the new lo cation of the no de is up dated only when: 1.The o verall maximum w arp of the fac es c onnec ted t o the no de has decr eased . 2.The o verall maximum sk ewness of the c ells c onnec ted t o the no de has decr eased or r emained the same . This is useful in r egions ha ving c omple x shar p corners , wher e the no des of a pr ism c ell ma y ha ve drastic nor mal change . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 392Gener ating P risms15.4. Prism M eshing Options f or Sc oped P risms Scoped pr ism c ontrols allo w you t o apply pr ism la yer par amet ers t o sp ecific r egions of the mesh objec t. Accessible thr ough the Auto M esh volume-meshing t ool, the scoped prism pr ocess first cr eates boundar y layers based on the defined c ontrols, and then pr oceeds t o gener ating the t et/he xcore mesh. Imp ortant •Volumetr ic regions need t o be comput ed pr ior t o objec t based v olume meshing .The c omputing of regions includes t opology checks , re-or ienting of nor mals , and baffle iden tification and handling b efore gener ating the v olume mesh. •The dir ection of pr ism gr owth do es not need t o be set up separ ately.The pr ism la yers ar e alw ays grown in to the r egions selec ted; nor mals ar e re-or iented acc ordingly when the r egions ar e comput ed. •The sc oped pr isms metho d do es not use an y of the settings made in the Prisms dialo g box or using the c ommands in the /mesh/prism menu . To set up sc oped pr ism c ontrols, selec t scoped from the Grow P risms drop-do wn list in the Auto M esh dialo g box and click Set... to op en the Scoped P risms dialo g box. •You use the Scope To drop do wn list t o selec t fluid or solid r egions . You c an selec t fluid-r egions ,solid-r egions , or named-r egions . If named-r egions is selec ted, you can en ter the r egion name (wildc ards supp orted) in the Volume Sc ope field or click the Browse butt on ( ) and selec t the r egions in the Volume Sc ope dialo g box. •Within the selec ted r egions , you use the Grow On drop-do wn list t o selec t the b oundar y type on which t o grow pr ism la yers. You c an use all-z ones for unr estricted b oundar y type. Alternatively, use only-w alls to sc ope pr ism growth b y wall b oundar y type.To sc ope pr isms b y boundar y name , use selec ted-lab els,selec ted- face-zones , or solid-fluid-in terface and en ter the name or pa ttern in the Boundar y Sc ope field , or click the Browse butt on ( ) to use the Boundar y Sc ope dialo g box. If interior baffles e xist, the Grow on b oth sides of baffles option will b e available .You c an cho ose to gr ow pr isms on b oth sides (default) or on a single side . In c ase of single side , use the Color b y Normal option (hot-k ey combina tion Ctrl+Shift+C and Ctrl+N) to see on wha t side (gr ay) the pr isms will gr ow. •You use the Offset M etho d drop do wn list t o selec t from unif orm,asp ect-ratio, or last-r atio as the pr ism offset metho d.The geometr ic growth metho d is used; you c an sp ecify the gr owth r ate as appr opriate. •A meaning ful Name is recommended . Imp ortant Fluen t Meshing supp orts multiple sc oped pr ism c ontrols, however only one sc oped pr ism control can b e applied t o a fac e zone in a giv en r egion. 393Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Prism M eshing Options f or Sc oped P rismsIn Figur e 15.23: Use of M ultiple Sc oped P rism C ontrols (p.394), prism la yers ar e gr own on adjac ent zones within the fluid r egion, but with multiple sc oped c ontrols defined .The pr ism layers ar e stair st epp ed t o obtain a gr adual tr ansition b etween the la yers. Also,solid-fluid- interface is selec ted fr om the Grow On drop-do wn list , to enable gr owth of diff erent numb er of la yers in the solid and fluid r egions . Figur e 15.23: Use of M ultiple Sc oped P rism C ontrols Note •The sc oped pr ism c ontrols c an b e read fr om a pr eviously sa ved file (*.pzmcontrol ) or c an b e written t o a file f or fur ther use . •The c ommand /mesh/scoped-prisms/set-no-imprint-zones enables y ou t o sp ecify boundar y zones which should not b e impr inted dur ing the pr ism gener ation. Proximit y Handling Onc e the initial pr ism la yers ar e gener ated, the pr ism mesh is impr oved b y a c ombina tion of optimiza tion- based smo othing and no de mo vemen t to smo oth the pr ism c ell la yers.The sc oped pr isms appr oach includes t wo steps of c ollision a voidanc e—la yer compr ession and stair st epping . Use the Growth Options butt on t o setup c ontrols t o avoid c ollision of pr ism la yers in pr oximal r egions . Enable Keep F irst L ayer O ffsets to pr eser ve the first off set heigh t as other la yers ar e mo dified t o pr event collisions . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 394Gener ating P rismsIn regions of close pr oximit y the pr ism la yers ar e first c ompr essed t o resolv e gaps and shar p corners , based on the Gap F actor and Max A spect Ratio specified . After this , cells ar e iden tified f or stair st epping — a p ost pr ism meshing pr ocess c arried out t o avoid prism la yer collision and main tain mesh qualit y. In ar eas wher e it is not p ossible t o meet the qualit y limit sp ecified b y the Stair S tepping Threshold , or wher e in tersec tions ar e det ected, the higher pr ism layers will b e remo ved and filled with p yramids and t etrahedr a as tr ansition elemen ts b etween the r e- maining la yers and the v olume fill. A list of lo cations wher e the pr ism la yers w ere stair st epp ed is pr inted in the c onsole . For pr ism meshing , it is r ecommended t o use ICEM CFD Q ualit y as the qualit y metho d sinc e it is mor e str ingen t than the Skewness metr ic. If the final mesh qualit y is not acc eptable , you c an use the Auto N ode M ove tool with ICEM CFD qualit y measur e to impr ove the mesh. Figur e 15.24: Stair S tepp ed P rism La yers in S harp Corner (p.395) sho ws an e xample of a shar p corner wher e the pr ism la yers ha ve been stair st epp ed. Figur e 15.24: Stair S tepp ed P rism L ayers in S harp Corner 15.5. Prism M eshing P roblems This sec tion discusses a numb er of c ommon pr oblems tha t you ma y enc oun ter when gener ating pr is- matic meshes . An appr opriate solution is also r ecommended f or each pr oblem. If the pr ism gener ation fails or is unsa tisfac tory, you ma y read in the mesh y ou sa ved b efore star ting the pr ism gener ation (in step 6 of Procedur e for C reating Z one-based P risms (p.369)) and r epeat the pr ocess, incorporating the appr opriate corrections . The most c ommon pr ism meshing pr oblems ar e: •Orientation •Retriangula tion failur es •Too man y or t oo few no des, or unk nown fac e combina tions •Negative volumes , left-handed fac es, or high sk ewness 395Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Prism M eshing P roblems•Growing t oo far •Large jumps in pr ism heigh t at the edges of la yers Orientation If the fac es of the b oundar y zone fr om which y ou ar e building pr isms ar e not all or iented in the same direction, you will b e aler ted tha t the fac es ha ve been r eoriented, and the pr ism gener ation pr ocess will pr oceed. Retr iangula tion F ailur es If no des, wher e adjac ent zones meet the z ones (fr om which pr isms ar e gr owing) ar e duplic ated, the mesher will b e una ware tha t the z ones ar e connec ted. It will ignor e such z ones when c onsider ing no des for pr ojec tion, and henc e retriangula tion is lik ely t o fail. Solution :To verify this pr oblem check the messages pr inted b efore the first pr ism la yer. It should contain a list of all the z ones c onnec ted t o the z ones fr om which y ou ar e gr owing the pr isms . 1. Make sur e ther e are no fr ee no des in the sur face mesh b efore gr owing an y pr isms . 2. Use the Coun t Free N odes butt on in the Merge B oundar y Nodes dialo g box to check f or fr ee no des. 3. Enable the Free option in the Faces sec tion of the Displa y Grid dialo g box to see wher e the fr ee no des are located. Too M any/Few N odes or U nknown F ace Combina tions If you r eceive the f ollowing t ype of messages , then y ou ar e most lik ely gr owing pr isms in to existing cells. Warning: wedge cell c887 has too many nodes Warning: wedge cell c1928 has too few nodes Warning: base_mask = 7 (0x7), unknown face combinations Either y ou ha ve alr eady gr own pr isms fr om the selec ted z ones , or y ou ar e gr owing them in the wr ong direction in to cells on the other sides of the selec ted z ones . In the la tter case, reorient the nor mals and growing the la yers. See st ep 4 in Procedur e for C reating Z one-based P risms (p.369). Nega tive Volumes/L eft-Handed F aces/High S kewness The pr ism la yer cr eation pr ocess will aut oma tically st op if nega tive cell v olumes , left-handed fac es, or high sk ewness ar e det ected. Left-handed fac es ar e fac es tha t ha ve collapsed in to their c ells.You c an view them b y enabling the Left Handed option in the Faces sec tion of the Displa y Grid dialo g box.Very high sk ewness o ccurs when the v alue of sk ewness is gr eater than the sp ecified Max. Allowable S kewness in the Impr ove sec tion of the Prisms dialo g box).These pr oblems c an o ccur wher e pr ism la yer fr onts ar e ad vancing t oo quick ly in ar eas of high cur vature. For e xample , the first la yer heigh t ma y be gr eater than the minimum edge length of y our or iginal sur face mesh. You should c ompar e the First H eigh t with the r esults of click ing the Edge S ize Limits butt on Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 396Gener ating P rismsin the Growth sec tion of the Prisms dialo g box.The First H eigh t should usually b e smaller than the minimum edge siz e. Solution : If the First H eigh t is reasonable but y ou ar e unable t o succ essfully gener ate your r equest ed Total H eigh t, try one of the f ollowing solutions: •Reduc e the First H eigh t or the par amet er used f or the gr owth Metho d (tha t is,Slope,Rate, or Exponen t), and incr ease the Numb er of L ayers. Extra layers allo w smo othing t o comp ensa te better for shar p edges and c orners . •If you ha ve sp ecified a nonz ero value f or Ortho gonal L ayers (in the Direct sec tion of the Prisms dialo g box), change it t o zero. Incr easing or thogonalit y can r educ e robustness . •If you ha ve reduc ed the Max. Angle C hange (in the Direct sec tion of the Prisms dialo g box) fr om its default of 70 degr ees t o impr ove or thogonalit y, reset it t o 70. •If you ha ve disabled edge sw apping or nor mal, offset, or edge smo othing , turn them back on. •If you ar e using the minimum-heigh t off set metho d (enabled with the mesh/controls/prism/offset- method text command), swit ch back t o the unif orm metho d. •Lower the Skewness for Swapping and S moothing in the Impr ove sec tion of the Prisms dialo g box. •Increase the numb er of Layers in the Impr ove sec tion of the Prisms dialo g box if it is smaller than the numb er of la yers b eing gr own. •Enable Smooth N odes in the Impr ove sec tion of the Prisms dialo g box.You c an also incr ease the numb er of smo othing r ings , using the c ommand: /mesh/controls/prism/node-smooth-rings •If you ar e gr owing simultaneously fr om multiple z ones , use z one-sp ecific gr owth c ontrols. Use smaller initial heigh ts and/or gr owth r ates for zones tha t are ha ving pr oblems . Growing Too Far The pr oblem her e is gr owing t oo man y layers. Ideally , to pr ovide f or a smo oth tr ansition t o the near ly- equila teral tetrahedr a, the v olume of the t etrahedr a should b e the lo cal gr owth r ate times the v olume of the last la yer pr ism c ells. Solution :To ensur e this do es not happ en, verify tha t the pr ism par amet ers sa tisfy the ab ove condition. Large Jumps in P rism H eigh t If the pr isms use quadr ilateral fac es of adjac ent zones , and the no de spacings on these fac es ar e very different from the la yer heigh ts, the pr ism heigh ts jump a t the out er edges . Solution :To fix this pr oblem, replac e the adjac ent quadr ilateral fac e zones with tr iangular fac e zones , using the /boundary/remesh/triangulate text command .When y ou r eattempt the pr ism gen- eration, the z one will b e pr ojec ted t o and r etriangula ted. Because the out er no des of the pr isms ar e pr ojec ted t o the adjac ent boundar y zone , and the or iginal nodes on tha t portion of the z one ar e disc arded , the diff erent no de spacing on the adjac ent zone will not aff ect the pr ism heigh ts at the out er edges . 397Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Prism M eshing P roblemsRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 398Chapt er 16: Gener ating Tetrahedr al M eshes This chapt er descr ibes ho w to cr eate the t etrahedr al mesh in the domain. It also descr ibes some of the common pr oblems fac ed dur ing t etrahedr al meshing . You c an use one of the f ollowing t echniques t o gener ate tetrahedr al meshes: •Automa tic mesh gener ation (see Automa tically C reating a Tetrahedr al M esh (p.399)) •Manual mesh gener ation (see Manually C reating a Tetrahedr al M esh (p.403)) •A combina tion of manual and aut oma tic c ommands (see Initializing the Tetrahedr al M esh (p.406),Refining the Tetrahedr al M esh (p.407)) If the c ells (f or e xample , prisms or p yramids) ha ve alr eady been cr eated in some p ortion of the c ompu- tational domain, you need t o cr eate a domain enc ompassing the r egion t o be meshed with t etrahedr al cells b efore star ting with the t etrahedr al mesh gener ation. See Using D omains t o Group and M esh Boundar y Faces (p.468) for details . In such c ases , all aut oma tic and/or manual meshing ac tions will apply only t o the ac tive domain. Alternatively, inst ead of cr eating a new domain, you c an sp ecify the c ell z ones t o be pr eser ved while gener ating the t etrahedr al mesh, before pr oceeding with the mesh gener ation. You c an use the c ommand /mesh/tet/preserve-cell-zone to sp ecify the c ell z ones t o be pr eser ved. 16.1. Automa tically C reating a Tetrahedr al M esh The Mesh → Auto M esh feature contains c ommands tha t enc apsula te the r ecommended v olume mesh gener ation str ategy.The star ting p oint for this pr ocedur e is a v alid sur face mesh. 16.1.1. Automa tic M eshing P rocedur e for Tetrahedr al M eshes 16.1.2. Using the A uto Mesh Tool 16.1.3. Automa tic M eshing of M ultiple C ell Z ones 16.1.4. Automa tic M eshing f or H ybrid M eshes 16.1.5. Further M esh Impr ovemen ts 16.1.1. Automa tic M eshing P rocedur e for Tetrahedr al M eshes The aut oma tic t etrahedr al mesh gener ation pr ocess is divided in to two fundamen tal tasks: initializa tion and r efinemen t. •The aut oma tic initializa tion pr ocedur e includes the f ollowing st eps: 1.Merging fr ee no des. 2.Deleting unused no des. 3.Impr oving the sur face mesh. 399Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.4.Initializing the mesh. 5.Gener ating and separ ating c ell regions . Imp ortant If the mesh fails t o initializ e, typic ally this indic ates a pr oblem with the sur face mesh. In some r are cases , the sliv er siz e (which is aut oma tically c omput ed) ma y need t o be changed .This ma y happ en f or domains in which the minimum b oundar y fac e siz e is very small as c ompar ed t o the domain e xtent.When changing the sliv er siz e, the r ule of thumb is tha t the sp ecified v alue should b e of the or der 1e-12 times the minimum face ar ea. •The aut oma tic r efinemen t procedur e includes the f ollowing st eps: 1.Sorting the b oundar y fac es b y siz e. 2.Refining the b oundar y cells. 3.Reverse sor ting c ells b y sk ewness . 4.Refining the ac tive cell z ones . 5.Swapping c ells based on sk ewness . 6.Reverse sor ting c ells b y sk ewness . 7.Smoothing the mesh. 8.Remo ving b oundar y sliv ers. You c an selec t either the ad vancing fr ont refinemen t, or the sk ewness-based r efinemen t of the t etra- hedr al mesh. The r efinemen t procedur e is r epeated a numb er of times . You c an c ontrol the numb er of r epetitions f or sk ewness-based r efinemen t by setting the Numb er of Levels in the Tet Refine C ontrols dialo g box. For each subsequen t level of r efinemen t, the c ell skewness thr esholds ar e lowered. Additional r efinemen t levels incr ease the mesh r esolution (and the numb er of c ells) and decr ease the a verage c ell sk ewness . Each r efinemen t level ac tually c onsists of t wo sw eeps thr ough the r efinemen t procedur e: •One sw eep a t the appr opriate sk ewness thr eshold f or tha t par ticular le vel of r efinemen t. •Another sw eep with a high sk ewness thr eshold and a r elax ed Min B oundar y Closeness set in the Tet Refine C ontrols dialo g box. This sw eep a ttempts t o reduc e highly sk ewed c ells in c onfined r egions of the geometr y. Boundar y sliv ers will b e remo ved af ter the r efinemen t sw eeps ar e complet e if the Remo ve Slivers option is enabled in the Refinemen t tab of the Tet dialo g box. In some r are cases , it ma y happ en tha t the first sw eep of the first r efinemen t level will ne ver finish because mor e sk ewed c ells ar e formed due t o refinemen t, which will b e fur ther r efined t o cr eate mor e skewed c ells, and so on. Such a pr oblem ma y occur when ther e is a pr oblem with the b oundar y mesh, Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 400Gener ating Tetrahedr al M eshessuch as r apid mesh tr ansition in small gaps , and so on. You c an a void this pr oblem b y using the incr e- men tal impr ovemen t option f or the r efinemen t par amet ers or b y incr easing the Min N ode C loseness value in the Tet Refine C ontrols dialo g box. You c an selec t the fast tr ansition option f or the r efinemen t par amet ers in or der t o gener ate a mesh with a smaller numb er of c ells.When this option is selec ted, appr opriate refinemen t par amet ers will be used t o gener ate fewer cells dur ing meshing .The r ate of change of the c ell siz e is incr eased in or der to reduc e the numb er of c ells gener ated. Alternatively, you c an sp ecify an appr opriate cell sizing option with a sufficien tly lar ge v alue f or the gr owth r ate. Imp ortant Various st eps in the aut oma tic meshing pr ocess c an b e added or elimina ted using the Tet dialo g box. In addition, most asp ects of the aut oma tic meshing pr ocess c an b e changed dynamic ally thr ough the Scheme in terface. Contact your supp ort engineer f or details . 16.1.2. Using the A uto M esh Tool You c an use the Mesh → Auto M esh tool to aut oma tically: •Gener ate a t etrahedr al volume mesh star ting fr om a b oundar y mesh. •Gener ate a t etrahedr al volume mesh in an unmeshed domain of a mesh tha t contains other c ell shap es. The Auto M esh tool enables y ou t o gener ate the t etrahedr al volume mesh aut oma tically.When y ou selec t Tet in the Volume F ill list and click Mesh in the Auto M esh dialo g box: •If the v olume mesh do es not e xist, all the st eps list ed in Automa tic M eshing P rocedur e for Tetrahedr al Meshes (p.399) will b e performed . •If a v olume mesh alr eady exists , a Question dialo g box will app ear, ask ing if y ou w ant to clear the e xisting mesh. If you click Yes, the v olume mesh will b e clear ed and the ac tive steps in the aut oma tic mesh gener- ation pr ocess will b e performed . If you click No, the op eration will b e canceled . Imp ortant You c an use the c ommand /mesh/tet/preserve-cell-zone to sp ecify the c ell zones t o be pr eser ved dur ing mesh gener ation and click Mesh to pr oceed with the automa tic mesh gener ation. 16.1.3. Automa tic M eshing of M ultiple C ell Z ones The Auto M esh tool enables y ou t o mesh multiple c ell z ones aut oma tically.This is useful when the mesh has multiple c ell z ones (f or e xample , the pr oblem r equir es a fluid z one and one or mor e solid zones). You c an r efine the mesh using r efinemen t par amet ers sp ecific t o individual z ones , if requir ed. The pr ocedur e for meshing multiple c ell z ones includes the f ollowing st eps: 1.Initializ e the mesh. 2.Activate the appr opriate zones using the Manage C ell Z ones dialo g box. 401Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Automa tically C reating a Tetrahedr al M esh3.Set the z one-sp ecific r efinemen t par amet ers and r efine the ac tive zones . If you w ant to mesh all the z ones included in the mesh with the same r efinemen t par amet ers, modify the Non-F luid Type in the Tet dialo g box. Imp ortant By default , the Non-F luid Type is set t o dead as the mesh is assumed t o consist of a single fluid r egion and one or mor e dead r egions .The ac tive zone is c onsider ed t o be the fluid z one and only this fluid z one will b e consider ed f or refinemen t dur ing the automa tic meshing pr ocess. When the Non-F luid Type is set t o a t ype other than dead (for e xample ,solid ), all the zones will b e ac tive af ter the initializa tion is c omplet e. Hence, all the z ones will b e con- sider ed f or refinemen t. If requir ed, you c an change the z one t ype using the Manage Cell Z ones dialo g box. Selec t the appr opriate type from the Non-F luid Type drop-do wn list in the Tet Z ones group b ox in the Tet dialo g box before initializing the mesh. Note For z one-based meshing , if an y cell z one has a t least one b oundar y zone t ype as inlet , it will aut oma tically b e set t o fluid t ype. For objec t based meshing , volume r egion t ype is used t o det ermine the c ell z one t ype. 16.1.4. Automa tic M eshing f or H ybrid M eshes The Auto M esh tool can also cr eate pr isms and p yramids aut oma tically, allo wing aut oma tic gener ation of h ybrid meshes . •If a mix of sur face mesh t ypes (quadr ilateral and tr iangular) is pr esen t in the domain, pyramid c ell z ones will b e created on the quadr ilateral boundar y fac es b efore meshing the t etrahedr al domain. •If prism gr owth par amet ers ha ve been a ttached t o a b oundar y zone (using the Prisms dialo g box), the prism la yers will b e aut oma tically e xtruded b efore meshing the t etrahedr al domain. When p yramids or pr isms ar e gener ated using the aut oma tic mesh gener ation f eature, the in terme- diate boundar y zones will b e mer ged aut oma tically af ter the t etrahedr al mesh gener ation is c omplet e. This enhanc emen t avoids the cr eation of additional b oundar y zones such as prism-side and pyramid- cap (see Zones C reated D uring P rism G ener ation (p.369) and Zones C reated D uring P yramid G ener- ation (p.354)). •You c an tr ansition fr om quad t o tri fac es using the Non C onformals option. This option is useful when y ou want to avoid p yramids on quad fac es when gr owing pr isms fr om a b oundar y. For mix ed sur face mesh types (quadr ilateral and tr iangular), you c an selec t Non C onformal in the Quad Tet Transition list in the Auto M esh dialo g box.The sur faces c ontaining quad fac es will b e copied and tr iangula ted, keeping the original fac es in tact.The fr ee no des of the tr iangula ted sur face will then b e mer ged with the no des of the original sur face mesh and b oth the sur faces will b e converted t o interface type. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 402Gener ating Tetrahedr al M eshes16.1.5. Further M esh Impr ovemen ts Examine the f ollowing af ter completing the aut oma tic mesh gener ation pr ocess: •The mesh siz e with the Rep ort Mesh S ize dialo g box (see also Determining M esh S tatistics (p.491)). •The pr ism la yer cell qualit y distr ibution (see Determining B oundar y Cell Q ualit y (p.494)), if appr opriate. •The t et cell qualit y reports (see also Determining Volume M esh Q ualit y (p.493)). It is t ypic ally p ossible t o reduc e the maximum sk ewness t o the r ange 0.8–0.9. Skewness v alues higher than 0.9 ar e typic ally obtained due t o constr aints imp osed b y the sur face meshes . If you still ha ve highly sk ewed c ells apply additional sw apping and smo othing t o impr ove the qualit y (see Smoothing Nodes (p.451) and Swapping (p.452)).To incr ease the densit y of the mesh lo cally, use r efinemen t regions (see Using L ocal Refinemen t Regions (p.408)). Warning Do not o ver-refine the mesh. The v olume mesh pr oduced should b e of sufficien t densit y to resolv e the shap e of the geometr y.The mesh c an b e impr oved mor e eff ectively using the solution-adaptiv e mesh c apabilit y pr ovided in the solution mo de in F luen t. 16.2. Manually C reating a Tetrahedr al M esh In addition t o the Auto M esh tool, you c an c ontrol the t etrahedr al mesh gener ation pr ocess b y mo di- fying par amet ers a t each st ep.The basic op erations ar e descr ibed her e, and the metho ds for mo difying the asso ciated par amet ers ar e descr ibed in Initializing the Tetrahedr al M esh (p.406) and Refining the Tetrahedr al M esh (p.407). 16.2.1. Manual M eshing P rocedur e for Tetrahedr al M eshes 16.2.1. Manual M eshing P rocedur e for Tetrahedr al M eshes The basic c omp onen ts of the manual meshing pr ocess ar e examining and r epair ing the sur face mesh, creating an initial mesh, refining the mesh, and impr oving the mesh. The f ollowing st eps descr ibe the r ecommended meshing pr ocedur e. Step 1: Examining the S urface Mesh The first st ep in the mesh gener ation pr ocess is t o examine the v alidit y and qualit y of the sur face mesh. The r ecommended appr oach includes the f ollowing st eps: 1.Check ing f or fr ee and isola ted no des (see Free and I sola ted N odes (p.273)). 2.Check ing and impr oving the sur face mesh qualit y (see Impr oving B oundar y Sur faces (p.288)). 3.Visually e xamining the sur face mesh f or fr ee, multiply-c onnec ted, skewed, and/or close-pr oximit y fac es (see Displa ying the M esh (p.475)). 4.Making lo cal repairs if r equir ed (see Modifying the B oundar y Mesh (p.280)). After obtaining a v alid, (ideally) high-qualit y sur face mesh, you c an pr oceed t o cr eate the v olume mesh. 403Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Manually C reating a Tetrahedr al M eshStep 2: Creating the Initial Mesh The first st ep in gener ating the v olume mesh is cr eating the initial mesh. This pr ocess first cr eates a pre-meshed b ox enc ompassing the en tire geometr y, and then sequen tially in troduces each b oundar y node in to the mesh. As the no des of a b oundar y fac e ar e inser ted in to the mesh, any nec essar y mesh modific ations needed t o inser t the fac e ar e performed , effectively inser ting b oth b oundar y no des and faces in to the mesh simultaneously . For mor e inf ormation see Initializing the Tetrahedr al M esh (p.406). Activating M ultiple Z ones (f or M ulti-z one M eshes Only) If the mesh has multiple r egions (f or e xample , the pr oblem r equir es a fluid z one and one or mor e solid z ones), you c an r efine the mesh using r efinemen t par amet ers sp ecific t o individual z ones , if re- quir ed.The pr ocedur e for meshing multiple c ell z ones includes the f ollowing st eps: 1. Initializ e the mesh. 2. Activate the appr opriate zones using the Manage C ell Z ones dialo g box. 3. Set the z one-sp ecific r efinemen t par amet ers and r efine the ac tive zones . If you w ant to mesh all the z ones included in the mesh with the same r efinemen t par amet ers, modify the Non-F luid Type in the Tet dialo g box. Selec t the appr opriate type from the Non-F luid Type drop-do wn list in the Tet Z ones group b ox in the Tet dialo g box. Imp ortant By default , the Non-F luid Type is set t o dead as the mesh is assumed t o consist of a single fluid r egion and one or mor e dead r egions .The ac tive zone is c onsider ed t o be the fluid z one and only this fluid z one will b e consider ed f or refinemen t dur ing the automa tic meshing pr ocess. When the Non-F luid Type is set t o a t ype other than dead (for e xample ,solid ), all the zones will b e ac tive af ter the initializa tion is c omplet e. Hence, all the z ones will b e consider ed f or refinemen t. If requir ed, you c an change the z one t ype using the Manage Cell Z ones dialo g box. Note For z one-based meshing , if an y cell z one has a t least one b oundar y zone t ype as inlet , it will aut oma tically b e set t o fluid t ype. For objec t based meshing , volume r egion t ype is used t o det ermine the c ell z one t ype. Step 3: Refining the Mesh You will r efine the initial mesh b y adding c ells a t the b oundar y and in the in terior.The r efinemen t metho ds a vailable ar e the sk ewness-based metho d and the ad vancing fr ont metho d.You c an also define lo cal refinemen t regions using the Tet Refinemen t Region dialo g box.You c an mo dify the paramet ers in the Refinemen t tab of the Tet dialo g box and selec t additional r efinemen t options f or skewness-based r efinemen t in the Tet Refine C ontrols dialo g box, if requir ed. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 404Gener ating Tetrahedr al M eshesStep 4: Impr oving the Mesh You c an impr ove the sk ewness b y smo othing , swapping , and r efining the mesh fur ther t o impr ove the qualit y of the v olume mesh. At an y point in the mesh gener ation pr ocess, you c an c omput e and plot the c ell sk ewness distr ibution using the Cell D istribution dialo g box.The numb er of c ells in the specified r ange in each of the r egular ly spac ed par titions is displa yed in a hist ogram f ormat.The x axis sho ws either the siz e or the qualit y and the y axis giv es the numb er of c ells or the p ercentage of the t otal. This will giv e you an idea of the impr ovemen t requir ed. It is t ypic ally p ossible t o reduc e skewness t o 0.8–0.85 (f or simple geometr ies) or 0.9–0.95 (f or mor e comple x geometr ies). Note If you ha ve used domains t o gener ate the mesh or gr oup z ones f or reporting (as descr ibed in Using D omains t o Group and M esh B oundar y Faces (p.468)), you c an r eport the c ell dis- tribution only f or those c ell z ones tha t are in the ac tive domain. Step 4a: Swapping and S moothing without Refining Swapping and smo othing impr ove the mesh b y manipula ting the no des and fac es without incr easing the t otal numb er of c ells. Refinemen t, on the other hand , impr oves the mesh b y adding no des, which typic ally incr eases the numb er of c ells.To get the b est p ossible mesh with the minimum numb er of cells, perform only smo othing and sw apping b efore refining the mesh an y fur ther . Smoothing r epositions in terior no des t o lo wer the maximum sk ewness of the mesh. For sw apping , given n+2 no des in dimension n, ther e ar e at most t wo triangula tions of the no des dep ending on the configur ation of the no des. In c ases wher e two triangula tions e xist, the t wo alt ernatives ar e examined , and the one tha t has the lo west maximum sk ewness is selec ted. Smoothing and sw apping ar e aut o- matically p erformed t o impr ove the mesh when the Impr ove M esh option is enabled in the Refinemen t tab of the Tet dialo g box. Refer to Smoothing N odes (p.451) and Swapping (p.452) for details on impr oving the mesh b y sw apping and smo othing . Step 4b: Further Refinemen t You c an fur ther r efine the c ells in the ac tive zones b y changing par amet ers such as Max C ell Volume , and Max C ell S kew and Max B oundar y Cell S kew (available only f or sk ewness-based r efinemen t). Imp ortant Changing mesh siz e controls other than Max C ell Volume will ha ve no eff ect on a mesh that has alr eady been r efined . Alternately, use lo cal refinemen t regions . Refer to Using Local Refinemen t Regions (p.408) for details . Refining with sk ewness par amet ers r educ ed t o values less than 0.5 will r arely impr ove the mesh and will b e very time-c onsuming . Imp ortant Do not o ver-refine the mesh, the v olume mesh pr oduced should b e of sufficien t densit y to resolv e the shap e and an y intuitiv e flo w features (f or e xample , wall b oundar y layers). Addi- 405Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Manually C reating a Tetrahedr al M eshtional r esolution c an b e mor e eff ectively pr oduced using the solution-adaptiv e mesh c ap- abilit y pr ovided in the solution mo de in F luen t. At this st ep y ou will ha ve an acc eptable mesh f or most geometr ies. Step 4c: Boundar y Slivers and O ther S our ces of Linger ing High S kewness When viewing the c ell distr ibution plot , if y ou find tha t ther e ar e a f ew c ells with v ery high sk ewness , check t o see wher e the y are lo cated (tha t is, on the b oundar y or in the in terior). To do so , use the Rep ort Boundar y Cell Limits dialo g box.When using tha t dialo g box, not e tha t if y ou ha ve used domains t o gener ate the mesh or gr oup z ones f or reporting (as descr ibed in Using D omains t o Group and M esh B oundar y Faces (p.468)), the r eport will apply only t o the ac tive domain. Refer to Remo ving S livers fr om a Tetrahedr al M esh (p.454) and Moving N odes (p.458) for details on remo ving sliv ers and other mesh impr ovemen t options . You c an initializ e and r efine the t etrahedr al mesh in a single st ep b y click ing the Init & Refine butt on in the Tet dialo g box after setting the appr opriate par amet ers in the Initializa tion and Refinemen t tabs . Alternatively, you c an set the appr opriate par amet ers in the Initializa tion tab and click the Init butt on t o cr eate the initial mesh. You c an then r efine the initial mesh b y setting the appr opriate paramet ers in the Refinemen t tab and click ing the Refine butt on. If you need t o refine a par ticular r egion, you c an define the r egion t o be refined using the Tet Refine- men t Region dialo g box. 16.3. Initializing the Tetrahedr al M esh The first st ep in the v olume mesh gener ation pr ocess is initializa tion. The initial mesh c onsists of the nodes and tr iangles of the b oundar y sur face mesh. For some geometr ies, it is not p ossible t o cr eate a tetrahedr al mesh fr om the b oundar y no des alone . In such c ases , a small numb er of no des ar e aut oma t- ically added in the in terior of the domain. Interior no des ma y also ha ve to be added t o resolv e numer- ical pr oblems asso ciated with the D elauna y criterion. 16.3.1. Initializing U sing the Tet D ialog Box 16.3.1. Initializing U sing the Tet D ialo g Box You c an use Mesh → Tet to initializ e the mesh using the options a vailable in the Initializa tion tab of the Tet dialo g box. 1. Selec t the appr opriate ac tions t o be performed dur ing initializa tion fr om the Options group b ox. The Merge F ree N odes and Delet e Unused N odes options ar e enabled b y default. You c an also include impr oving the sur face mesh in the mesh initializa tion pr ocess b y enabling the Impr ove Surface M esh option. 2. Selec t the appr opriate option fr om the Non-F luid Type drop-do wn list. Enable Delet e Dead Z ones , if requir ed. When the initial mesh is gener ated, all the c ells ar e gr oup ed in to contiguous z ones separ ated b y boundar ies.The mesh is c onsider ed t o contain a single fluid z one and one or mor e dead r egions . The z one just inside the out er b oundar y is set t o be ac tive and is lab eled a fluid z one . All other Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 406Gener ating Tetrahedr al M eshesnon-fluid z ones will b e inac tive. Only ac tive zones will b e consider ed f or refinemen t dur ing the mesh gener ation pr ocess. Note For z one-based meshing , if an y cell z one has a t least one b oundar y zone t ype as inlet , it will aut oma tically b e set t o fluid t ype. For objec t based meshing , volume r egion t ype is used t o det ermine the c ell z one t ype. You c an r efine diff erent groups of z ones using diff erent refinemen t par amet ers f or each gr oup by toggling the z ones b etween ac tive and inac tive. If ho wever, you need t o use the same r efine- men t par amet ers f or all the z ones , you c an change the sp ecific ation of Non-F luid Type to a t ype other than dead (for e xample ,solid ).When the Non-F luid Type is set t o a t ype other than dead , all the z ones will b e ac tivated af ter initializa tion. Hence, you c an set the appr opriate refinemen t paramet ers without setting all the z ones t o be ac tive. 3. Specify additional initializa tion par amet ers, if requir ed.These par amet ers ar e available in the Tet Init Controls dialo g box. Click the Controls... butt on t o op en the Tet Init C ontrols dialo g box. 4. Click Init to initializ e the mesh. A Working dialo g box will app ear, informing y ou tha t the initializa tion is in pr ogress. Click the Canc el butt on in the Working dialo g box to ab ort the mesh initializa tion pr ocess. Canceling the initializa tion will lea ve the mesh inc omplet e. •If you tr y to initializ e the mesh af ter canceling an initial a ttempt , a dialo g box will ask if it is OK t o clear the inc omplet e mesh. After y ou appr ove, the initializa tion pr ocess will b egin again. •If you tr y to initializ e the mesh when duplic ate no des e xist, the initializa tion will fail. You must clear the mesh and mer ge the duplic ate no des b efore attempting the initializa tion again. •If you tr y to initializ e the mesh when a v olume mesh alr eady exists , a Question dialo g box will app ear, asking if y ou w ant to clear the e xisting mesh. If you click Yes, the v olume mesh will b e clear ed and then the mesh will b e initializ ed. If you click No, the op eration will b e canceled . •If you need t o pr eser ve the e xisting mesh dur ing the meshing pr ocess, use the c ommand /mesh/tet/preserve-cell-zone to sp ecify the c ell z ones t o be pr eser ved and click the Init butt on t o pr oceed with the initializa tion. •If the initial mesh gener ation fails , check the v alidit y of the sur face mesh. In some r are cases , you ma y need t o change the sliv er siz e par amet er (b y using the Tet dialo g box). Refer to Common Tetrahedr al M eshing P roblems (p.410) for mor e inf ormation on meshing pr oblems . 16.4. Refining the Tetrahedr al M esh After initializing the mesh, you c an impr ove the qualit y and densit y of the mesh using global and lo cal refinemen t. Global r efinemen t enables y ou t o refine all c ells in the ac tive zones , while lo cal refinemen t enables y ou t o refine c ells within a sp ecified r egion. 407Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Refining the Tetrahedr al M eshIn most applic ations , you will use only global r efinemen t to cr eate an acc eptable discr etiza tion of the volume . Local refinemen t is used t o mo dify the gr ading a way from b oundar ies or incr ease the r esolution of an in terior r egion of the mesh. You need t o define and ac tivate the r egions t o be refined b efore proceeding . The r efinemen t process includes a ser ies of sw eeps thr ough a sequenc e of sor ting , refining , reverse sorting , and sw apping and smo othing of the c ells.You c an sp ecify the numb er of r efinemen t levels t o be performed f or sk ewness-based r efinemen t. Each r efinemen t level consists of t wo iterations thr ough the r efinemen t procedur e. For each subsequen t level of r efinemen t, the c ell sk ewness thr esholds ar e lowered. Additional r efinemen t levels will incr ease the mesh r esolution (and the numb er of c ells) and decr ease the a verage c ell sk ewness .The pr eset r efinemen t control par amet ers ar e available in the Tet Refine C ontrols dialo g box. Alternatively, you c an selec t the ad vancing fr ont refinemen t metho d. Specify whether the mesh has t o be impr oved or if the sliv ers ha ve to be remo ved dur ing r efinemen t. •The Impr ove M esh option p erforms additional smo othing and sw apping with lo wered sk ewness thr esholds , attempting t o impr ove the a verage sk ewness of the mesh. •The Remo ve Slivers option a ttempts t o lower the maximum sk ewness b y impr oving highly sk ewed (sliv er) cells.There are two appr oaches f or sliv er remo val: fast and aggr essiv e. Both metho ds use the same c ontrols and giv e similar r esults f or go od qualit y sur face meshes . In c ase of p oor sur face meshes (meshes with lar ge size diff erence between neighb oring elemen ts, nar row gaps with widely v arying mesh siz es on either side of the gap , and so on), the aggr essiv e metho d will t ypic ally succ eed in impr oving the mesh t o a gr eater extent, but it ma y be slo wer than the default fast metho d. The aggr essiv e metho d corresponds t o the Impr ove option in the Tet Impr ove dialo g box. The b oundar y mesh is fix ed dur ing the mesh impr ovemen t and sliv er remo val op erations . Refinemen t Controls The r efinemen t controls f or the sk ewness metho d ar e available in the Tet Refine C ontrols dialo g box. Click the Controls... butt on in the Refinemen t tab of the Tet dialo g box to op en the Tet Refine C ontrols dialo g box. The r efinemen t controls f or the ad vancing fr ont metho d ar e available in the /mesh/tet/con- trols/adv-front-method menu .The /mesh/tet/controls/adv-front-method/skew- improve/target? command is imp ortant as it enables y ou t o enable tar geted sk ewness-based r e- finemen t for the ad vancing fr ont metho d.The r efinemen t process will a ttempt t o reach the tar geted skewness (sp ecified b y the c ommand /mesh/tet/controls/adv-front-method/skew-im- prove/target-skew ).Though the default v alues w ork well in most situa tions , it ma y be ad vantageous to incr ease the target-skew value in some c ases (f or e xample , cases wher e a c ombina tion of a p oor surface mesh and nar row gaps will r esult in p oor c ells in the mesh) t o incr ease the meshing sp eed. 16.4.1. Using L ocal Refinemen t Regions 16.4.2. Refinemen t Using the Tet D ialog Box 16.4.1. Using L ocal Refinemen t Regions A refinemen t region limits r efinemen t to sp ecific c ells inside the domain. When y ou use the Refine option in the Tet Refinemen t Region dialo g box, the c ells within the ac tivated r egions ar e refined . The pr imar y use of r efinemen t regions is t o reduc e the c ell siz e in the r egion t o less than it w ould b e normally . Currently, the only p ossible r egion shap e is a b ox, which c an b e or iented as r equir ed. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 408Gener ating Tetrahedr al M eshesThe r egion is defined b y an x,y, and z range and its or ientation ab out the x,y, and z axes. Any cell within the r egion or tha t intersec ts the r egion will b e subjec ted t o the r efinemen t criteria.You c an control the c oncentration of in terior no des b y sp ecifying the maximum c ell v olume in the r efinemen t region. It is p ossible t o sa ve diff erent values f or the Maximum C ell Volume when y ou sa ve each r egion. You c an also sp ecify an out er region with the r equir ed v olume gr owth t o ha ve a smo oth tr ansition between the or iginal and the r efined c ells. Note In addition t o the use of r efinemen t regions f or refinemen t dur ing the mesh gener ation process, the y can also b e used as a p ostpr ocessing t ool to refine a r egion of an e xisting mesh. You c an cr eate multiple r egions tha t overlap each other and the geometr y.To cr eate additional r egions , you c an c opy an e xisting r egion and then mo dify the par amet ers as r equir ed.The default r egion includes the en tire geometr y. Figur e 16.1: Local Refinemen t Region f or the Tetrahedr al M esh (p.409) sho ws the r efinemen t region and out er region. The maximum c ell siz e for the r efinemen t and out er regions is displa yed based on the maximum c ell v olume and outside v olume gr owth sp ecified . For inf ormation on r efining tr iangular boundar y fac es in an ticipa tion of lo cal refinemen t, refer to Refining the B oundar y Mesh (p.289). Figur e 16.1: Local Refinemen t Region f or the Tetrahedr al M esh 16.4.2. Refinemen t Using the Tet D ialo g Box You c an use Mesh → Tet to refine the mesh using the options a vailable in the Refinemen t tab of the Tet dialo g box. 1. Selec t the appr opriate refinemen t metho d from the Refine M etho d drop-do wn list. 2. Enable the appr opriate options in the Options group b ox. 409Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Refining the Tetrahedr al M esh3. Specify an appr opriate value f or Max C ell Volume . 4. Selec t the appr opriate option fr om the Cell S izing drop-do wn list. Ensur e tha t the c ells in the in terior ar e not lar ger than the siz e requir ed b y selec ting the appr opriate option in the Cell S izing list. The f ollowing options ar e available: geometr ic specifies tha t the c ell siz e in the in terior of the domain is obtained b y a geometr ic gr owth fr om the closest b oundar y acc ording t o the gr owth r ate sp ecified . size-field specifies tha t the c ell siz e is det ermined based on the cur rent siz e-field . Note Additional c ell sizing options ( none (for sk ewness-based r efinemen t only) and linear ) are available only via t ext commands . See the Text Command List for details . 5. Modify the r efinemen t control par amet ers, if requir ed. •For the sk ewness metho d, click the Controls... butt on t o op en the Tet Refine C ontrols dialo g box. Selec t the appr opriate option fr om the Preset P aramet ers drop-do wn list. Verify the par amet er values in the Tet Refine C ontrols dialo g box and mo dify the v alues as appr opriate. •For the ad vancing fr ont metho d, use the c ommands a vailable in the /mesh/tet/controls/adv- front-method menu .You c an also sp ecify the tar geted sk ewness f or the r efinemen t process (see Refinemen t Controls (p.408) for details). 6. To refine sp ecific r egions of the mesh, click the Local Regions ... butt on t o op en the Tet Refinemen t Region dialo g box. Define the r efinemen t regions and ac tivate them. The numb er of ac tivated r egions will b e reported in the Message field in the Refinemen t tab of the Tet dialo g box. 7. Click Refine to refine the mesh. 16.5. Common Tetrahedr al M eshing P roblems Most pr oblems with the mesh gener ation pr ocess b ecome manif est in the failur e to gener ate an initial mesh. There ar e two sour ces of such pr oblems: •An invalid sur face mesh •Incorrect sliv er siz e sp ecified Some of the c ommon pr oblems and suggestions f or check ing and fixing the mesh ar e descr ibed in this section. To lo ok a t the no des and fac es tha t ha ve not b een meshed , enable Unmeshed in the Displa y Grid dialo g box. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 410Gener ating Tetrahedr al M eshesDuplic ate Nodes or F aces Some c odes cr eate multiple c opies of the same no de wher e two boundar y cur ves or sur faces meet , resulting in a c onnec tivit y pr oblem. This pr oblem c an b e det ected b y reporting the numb er of fr ee nodes or b y dr awing the fr ee edges . If the geometr y do es not c ontain infinit ely thin w alls then ther e should not b e an y free no des or edges .You c an r emo ve duplic ate no des using the /boundary/de- lete-duplicate-nodes command . The pr esenc e of duplic ate fac es c an b e det ected in one of t wo ways: •If the no des of the duplic ate fac es ar e not shar ed b y the non-duplic ate fac es, the duplic ate fac es ma y ha ve free edges tha t can b e displa yed. •If the no des ar e not distinc t or ha ve been mer ged , ther e will b e multiply-c onnec ted edges . Note Duplic ate fac es c an b e handled , it is not nec essar y to remo ve them. Extra Nodes or F aces Nodes tha t are not used b y an y fac e ar e called unused no des.The unused no des c an easily b e found and delet ed using the Merge B oundar y Nodes dialo g box, if those no des ar e not r equir ed. However, ther e ar e cases wher e these additional no des ma y be useful (see Inser ting I sola ted N odes in to a Tet Mesh (p.346)). Extra fac es c an b e iden tified and r emo ved using the metho d descr ibed f or duplic ate faces. To mer ge no des tha t are not on a fr ee edge , in the Merge B oundar y Nodes dialo g box disable Only Free N odes in the Compar e... or With... group b ox or in b oth gr oup b oxes. For e xample , if y ou r ead a hybrid mesh c ontaining he xahedr al cells (and quadr ilateral b oundar y fac es) and tr iangular b oundar y faces, ther e ma y be some duplic ate no des on adjac ent quadr ilateral and tr iangular b oundar y zones .To mer ge them, compar e free no des on b oth z ones with all nodes on b oth z ones (tha t is, selec t both z ones in the Compar e... and With... group b oxes, and disable Only F ree N odes in one of them). Intersec ting F aces If ther e ar e in tersec ting fac es in the mesh, you will not b e able t o gener ate a mesh un til the pr oblem faces ar e remo ved. Most in tersec ting fac es c an b e lo cated using the /boundary/mark-face-inter- section command . If intersec ting b oundar y fac es ar e enc oun tered dur ing initializa tion, a message will b e displa yed. After the meshing fails , the unmeshed fac es c an b e dr awn t o see the pr oblem ar ea. Usually , because the in tersec ting fac e will ha ve been meshed , it will not b e dr awn and some additional sleuthing will be requir ed. Draw all the fac es near the unmeshed fac es b y setting displa y bounds (b y using the Displa y Grid dialo g box). Click the Mark butt on in the Intersec t Boundar y Zones dialo g box to highligh t the face in tersec tion. Alternatively, you c an use the c ommand /boundary/mark-face-intersection to highligh t the fac e in tersec tion. When y ou set the Feature Angle , not e tha t this sp ecifies the minimum angle b etween the f eature edges tha t should b e pr eser ved dur ing r etriangula tion. All the edges in the zone ha ving f eature angle gr eater than the sp ecified Feature Angle are retained .This option is useful for pr eser ving the shap e of the in tersec ting b oundar y zones . A v alue in the r ange of 10–50° is r ecom- mended; a lar ge v alue ma y dist ort the shap e of the in tersec ting b oundar y zones . 411Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Common Tetrahedr al M eshing P roblemsPoor B oundar y Node D istribution Some meshing pr oblems c an b e caused b y a p oor qualit y sur face mesh. The sur face mesh ma y ha ve highly sk ewed fac es, or t wo or mor e boundar ies in close pr oximit y ma y ha ve very diff erent fac e siz es. In the la tter case, the b oundar ies c an b e connec ted (f or e xample , in a c orner) or c omplet ely separ ate. Either w ay, the b oundar y mesh c annot b e created without c onsider ing the impac t of other nearb y boundar ies. If the gap b etween t wo boundar ies is D, the lar gest edge on a fac e should not e xceed D.The mesh qualit y is e xtremely imp ortant when a c oarse mesh is r equir ed in a small gap . Non-C losed B oundar ies You c an gener ate an initial mesh e ven if ther e is a hole in a b oundar y either due t o missing fac es or a gap b etween t wo zones . In this c ase, inst ead of ha ving t wo separ ate zones on opp osite sides of the boundar y, you will ha ve just one c ombined z one .This situa tion is e viden t because y ou will ha ve very few z ones . •If the hole is in the out er b oundar y, the c ells outside the b oundar y will b e combined with the c ells inside , resulting in an er ror.The edges ar ound the hole will b e mar ked as fr ee edges and ther efore can b e displa yed. •If the pr oblem is c aused b y a small gap b etween b oundar ies and the duplic ate no des ha ve alr eady been mer ged , incr ease the t oler ance and p erform additional mer ging . The f ollowing c ommand c an b e used t o det ect holes in the geometr y by tracing the pa th b etween the two sp ecified c ells: /mesh/tet/trace-path-between-cells A pa th b etween the selec ted c ells will b e highligh ted. Interior N ode N ear B oundar y During r efinemen t, a no de ma y be plac ed t oo close t o a b oundar y fac e, resulting in a highly sk ewed cell.You c an det ect this situa tion b y displa ying the highly sk ewed c ells.You c an then smo oth the mesh to elimina te the pr oblem. If the in terior no de is c onstr ained b y the b oundar y fac es, incr ease the Min B oundar y Closeness (in the Tet Refine C ontrols dialo g box) and r egener ate the mesh. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 412Gener ating Tetrahedr al M eshesChapt er 17: Gener ating the H excore M esh Hexcore meshing is a h ybrid meshing scheme tha t gener ates axis-aligned C artesian c ells inside the c ore of the domain and t etrahedr al cells close t o the b oundar ies. Hanging-no de (or H-) r efinemen ts on the Cartesian c ells enable efficien t cell siz e transition fr om b oundar y to in terior of the domain. This r esults in fewer cells with full aut oma tion and c an handle c omple x geometr ies, internal w alls and gaps . The he xcore meshing scheme is applic able t o all v olumes but is useful mainly f or v olumes with lar ge internal r egions and f ew in ternal b oundar ies such as in trusions or holes .The Hexcore submenu c ontains options t o control the he xcore mesh gener ation. The star ting p oint is a v alid sur face mesh. 17.1. Hexcore Meshing P rocedur e 17.2. Using the H excore Dialog Box 17.3. Controlling H excore Paramet ers 17.1. Hexcore M eshing P rocedur e You c an c ontrol the gener al shap e, size, and densit y of the c ore, as w ell as the siz e of elemen ts cr eated at the out er b oundar y of the c ore using the par amet ers in the Hexcore dialo g box and the c ommands in the /mesh/hexcore/ menu . There ar e two appr oaches a vailable f or gener ating the he xcore mesh. •The default Cartesian type. •The Octree type which supp orts the siz e controls defined , or the c omput ed siz e field .This r esults in fast er hexcore mesh gener ation. However, it do es not supp ort gener ation of he xcore mesh up t o boundar ies. When the Cartesian type is used , internally the f ollowing st eps ar e tak en t o gener ate the he xcore mesh: 1.Gener ating initial C artesian c ells inside a b ounding b ox (or the r egion sp ecified) ar ound the v olume t o be meshed . 2.Marking b oth, the C artesian c ells tha t intersec t the b oundar y mesh and those c ells ha ving siz es lar ger than the a verage siz e of the fac es the y intersec t. 3.Marking additional buff er-la yer cells adjac ent to the c ells mar ked in S tep 2 (if sp ecified). 4.Marking additional c ells t o enf orce one-le vel refinemen t diff erence between adjac ent cells. 5.Sub dividing all mar ked (in st eps 2–4) c ells and r epeating st eps 2–5 un til the lo cal fac e siz e criteria is met. 6.Deleting c ells tha t intersec t or ar e within some distanc e to the closest fac e on the sur face mesh. 413Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.7.Triangula ting the e xternal sur face of the he xcore by converting quads in to tri interface fac es.The quad faces b ecome par ents (with t ype parent-face ) of the in terface fac es. Note Pyramids ar e not used f or the tr ansition fr om the he xcore to the t etrahedr al cell r egions . 8.Smoothing the in terface fac es (if in terface smo othing is enabled). 9.Initializing and r efining the t etrahedr al cells b etween the in terface fac es and the b oundar y mesh. Note The maximum sk ewness r eported a t the end of the r efinemen t process is not nec essar ily the final maximum sk ewness . Sliver cells on the in terfaces c an b e remo ved a t a la ter stage . 10.Remo ving sliv er cells on the in terface fac es. 11.Merging C artesian c ells with t etrahedr al (and w edge , if pr esen t) cells t o form contiguous c ell z ones . When the Octree type is used , internally the f ollowing st eps ar e tak en t o gener ate the he xcore mesh. 1.A unif orm O ctree domain is initializ ed f or the r egion sp ecified b y the v olume t o be meshed . 2.The o ctants ar e refined t o local sur face mesh siz es and t o respect BOI siz e controls, if defined . If the siz e-field e xists , the O ctree r efinemen t will b e dr iven b y the siz e-field inst ead. 3.Peel la yers ar e enf orced. Cells tha t intersec t the sur face mesh or ar e within some distanc e to the sur face mesh ar e delet ed. 4.Buffer la yers ar e enf orced as applic able . 5.The e xternal sur face of the he xcore mesh is tr iangula ted, the quads ar e converted t o tri interface fac es. The quad fac es b ecome par ents (with t ype parent-face ) of the in terface fac es. Note Pyramids ar e not used f or the tr ansition fr om the he xcore to the t etrahedr al cell r egions . 6.The in terface fac es ar e smo othed (if in terface smo othing is enabled). 7.The t etrahedr al cells b etween the in terface fac es and the sur face mesh ar e gener ated. 8.The sliv er cells on the in terface fac es ar e remo ved. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 414Gener ating the H excore Mesh9.The he x cells ar e mer ged with t etrahedr al cells t o form contiguous c ell z ones . Imp ortant If prism par amet ers ha ve been a ttached t o boundar y zones , the pr ism la yers will first b e gener ated.The he xcore meshing pr ocedur e will then b e applied t o the r esulting pr ism c aps, along with the other b oundar y zones tha t were not in volved in the pr ism mesh gener ation. 17.2. Using the H excore Dialo g Box To cr eate a he xcore mesh using the Hexcore dialo g box, do the f ollowing: 1. Read in a b oundar y mesh and check and impr ove its qualit y, if nec essar y. 2. (optional) S plit an y quad fac es in the b oundar y mesh in to triangular fac es using the /bound- ary/remesh/triangulate command . By default , quad fac es ar e not allo wed while initializing the he xcore mesh. Alternatively, use the c ommand /mesh/non-conformals/controls/enable? to enable the creation of a non-c onformal in terface. If this option is enabled , all the sur faces ha ving quad elemen ts will b e copied and r emeshed with triangular fac es.The fr ee no des of the tr iangular mesh will b e mer ged with the or iginal sur face mesh. The metho d to be used f or retriangula tion c an b e sp ecified using the c ommand /mesh/non- conformals/controls/retri-method . The quad-split metho d is the default metho d used f or retriangula tion. You c an selec t prism , quad-split , or remesh as appr opriate. 3. Selec t the appr opriate option in the Type list. Retain the default selec tion of Cartesian or selec t the Octree type. 4. Specify the he xcore par amet ers. Some par amet ers (maximum c ell length or minimum c ell length) r equir ed dur ing the he xcore meshing ar e aut oma tically c alcula ted.The he xcore meshing par amet ers c an b e changed using the Hexcore dialo g box or using the c ommands in the /mesh/hexcore text menu . Note Some op erations , such as H excore only , are not a vailable f or objec t-based v olume meshing . Similar ly, options under the Zones group in the Hexcore dialo g box, tha t re- quir e a z one-based w orkflow, have no eff ect for objec t-based v olume meshing . 5. Click Create in the Hexcore dialo g box to gener ate the he xcore mesh. 415Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the H excore Dialog Box17.3. Controlling H excore Paramet ers The par amet ers tha t control the he xcore mesh gener ation c an b e changed using the Hexcore dialo g box.The f ollowing options ar e available: 17.3.1. Maximum or M inimum C ell L ength 17.3.2. Buffer La yers 17.3.3. Peel La yers 17.3.4. Defining H excore Ex tents 17.3.5. Only H excore 17.3.6. Local Refinemen t Regions 17.3.1. Maximum or M inimum C ell L ength The use of M aximum or M inimum c ell length is det ermined b y your choic e of Type. •When using the Cartesian type, the Max C ell L ength is used f or gener ating the initial C artesian c ells. An optimal maximum c ell length c an b e aut oma tically c alcula ted f or a par ticular mesh. Click the Comput e butt on ne xt to the Max C ell L ength field t o obtain the optimal maximum c ell length f or the mesh. Alternatively, specify the maximum c ell length as r equir ed. •When using the Octree type, the Min C ell L ength as set b y the global minimum siz e for sc oped sizing is used f or gener ating the he xcore mesh. Note Changing the default Min C ell L ength value will change the global minimum siz e for scoped sizing as w ell. If a siz e-field has b een c omput ed, the minimum c ell length will b e the global minimum siz e sp ecified for the siz e-field . 17.3.2. Buff er L ayers The C artesian c ells ar e mar ked (and subsequen tly sub divided) t o sa tisfy the siz e requir emen t on the boundar y mesh. When ther e is lar ge dispar ity in siz e distr ibution b etween the b oundar y mesh and the initial C artesian c ells, ther e will b e a r apid tr ansition fr om fine t o coarser c ells.To avoid this , addi- tional la yers of c ells ar e mar ked adjac ent to those mar ked b y the siz e requir emen t (see Figur e 17.1: Hex- core M esh U sing (A) B uffer La yers = 1 (B) B uffer La yers = 2 (p.417)).You c an c ontrol the numb er of additional la yers b y setting the Buff er L ayers in the Hexcore dialo g box.The default numb er of buff er layers is set t o 1. Setting the numb er of buff er la yers t o zero ma y result in a p oor qualit y mesh. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 416Gener ating the H excore MeshFigur e 17.1: Hexcore M esh U sing (A) Buff er L ayers = 1 (B) Buff er L ayers = 2 Note If the siz e-field has b een c omput ed and the O ctree t ype is used t o gener ate the mesh, the hexcore mesh siz e is dr iven b y the siz e-field . In this c ase, the numb er of buff er la yers is not requir ed. 17.3.3. Peel L ayers The p eel la yers c ontrol the gap b etween the he xahedr a core and the geometr y. After the C artesian cells ar e sub divided t o meet the siz e requir emen t, the c ells in tersec ted b y boundar y mesh and those within some distanc e to the closest fac e on the b oundar y mesh ar e delet ed.The default v alue f or Peel Layers is 1, henc e this distanc e is assumed t o be the heigh t of an ideal t etrahedr al cell on the boundar y fac e. If Peel L ayers is set t o 0, the gap siz e can b e smaller than the ideal heigh t.The r esulting hexcore mesh will c ontain the maximum numb er of C artesian c ells p ossible f or the chosen par amet ers. Figur e 17.2: Hexcore M esh U sing (A) P eel La yers = 0 (B) P eel La yers = 2 (p.417) sho ws the he xcore mesh gener ated f or diff erent values of Peel L ayers. Figur e 17.2: Hexcore M esh U sing (A) P eel L ayers = 0 (B) P eel L ayers = 2 417Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Controlling H excore Paramet ers17.3.4. Defining H excore Extents When using the Cartesian type, you c an cho ose t o cr eate the he xcore mesh up t o the b oundar y of the domain inst ead of cr eating a t etrahedr al mesh a t the b oundar y.The he xcore mesh e xtents can b e defined b y sp ecifying a b ox in which the he xcore mesh is t o be gener ated and/or a set of axis-aligned planar b oundar ies t o which the he xahedr al core is t o be extended .The e xtents can b e defined as f ollows: 1. Enable Define H excore Extents in the Hexcore dialo g box. 2. Click the Specify ... butt on t o op en the Out er D omain P aramet ers dialo g box. 3. Enable Coordina te Extents in the Out er D omain P aramet ers dialo g box.The minimum and maximum domain e xtents will b e aut oma tically up dated with v alues sligh tly gr eater than the b ounding b ox of the surface mesh in the domain. The c oordina te extents of the he xcore out er b ox can also b e sp ecified as requir ed. Imp ortant The he xcore mesh will e xtend t o the defined domain e xtents. A w arning will b e dis- played if the gap b etween the user-defined domain e xtents and geometr ic boundar ies is less than 20% of siz e of the b ounding b ox which c ontains the giv en geometr y. 4. Enable Draw Out er B ox and click Draw to verify tha t the domain e xtents ar e correctly defined . 5. Click Apply in the Out er D omain P aramet ers dialo g box. 6. Create the he xcore mesh. This f eature is useful f or the he xcore mesh gener ation f or e xternal flo w domains (f or e xample , external aerodynamics c ases wher e the b oundar y conformity is not needed f or far-field b oundar ies). This also helps incr ease the c oun t of he xahedr al cells in the mesh. In Figur e 17.3: Hexcore to the F ar-F ield B oundar y (p.419), the he xcore mesh has b een e xtended un til the domain b oundar y and do es not ha ve a t etrahedr al mesh a t the far-field b oundar y. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 418Gener ating the H excore MeshFigur e 17.3: Hexcore to the F ar-F ield B oundar y 17.3.4.1. Hexcore to Selec ted B oundaries You c an use the Boundar y Extents option in the Out er D omain P aramet ers dialo g box to impr int quad fac es on selec ted axis-aligned planar b oundar ies.The selec ted b oundar y will b e replac ed with a mix of quad- and tr i-fac e zones .You c an gener ate the he xcore mesh t o selec ted b oundar ies as f ollows: 1. Enable Define H excore Extents in the Hexcore dialo g box. 2. Click the Specify ... butt on t o op en the Out er D omain P aramet ers dialo g box. 3. Enable Boundar y Extents in the Out er D omain P aramet ers dialo g box and selec t the appr opriate planar , axis-aligned b oundar ies t o which the he xcore mesh is r equir ed. Note The planar b oundar ies must b e split in to separ ated b oundar y zones . Click Apply in the Out er D omain P aramet ers dialo g box. The he xcore box coordina tes will aut oma tically snap t o the selec ted b oundar ies. Enable Draw Out er B ox. Draw the out er b ox along with the selec ted b oundar ies t o verify tha t the b ox snaps t o the selec ted b oundar ies. If the b ox do es not snap t o a selec ted b oundar y, it indic ates tha t the he xcore mesh c annot b e grown t o the b oundar y. If the selec ted b oundar y zone is a plane which is misaligned with the axis, you c an align it using the Auto A lign option as f ollows: a. Selec t the z ones t o be aligned in the Boundar y Zones selec tion list. The Auto A lign group b ox will no w b e ac tivated. 419Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Controlling H excore Paramet ersb.Enable Auto Align . c.The r ecommended aut o align t oler ance value c an b e comput ed f or the selec ted set of b oundar y zones . Click Comput e to det ermine the r ecommended t oler ance or en ter an appr opriate toler ance value . d.Click Apply in the Auto Align group b ox to align the selec ted z ones which ar e within the t oler ance specified . Warning The Auto A lign option ma y def orm the geometr y permanen tly.Take care while selec ting the b oundar y zones . e.Draw the out er b ox along with the selec ted b oundar ies t o verify tha t the b ox has snapp ed t o the selec ted b oundar ies. 4. Enable Delet e Old F ace Zones , if requir ed and click Apply in the Out er D omain E xtents dialo g box. 5. Create the he xcore mesh. The newly cr eated quad fac e zones will b e named with the or iginal z one names . The he xcore mesh will e xtend t o the selec ted b oundar ies, aligned with the X,Y, and Z axes. An example is sho wn in Figur e 17.4: Hexcore to Boundar ies (p.420). Warning If you a ttempt t o use this option when the geometr y is c omplet ely within the domain, an error will b e reported. Figur e 17.4: Hexcore to Boundar ies 17.3.5. Only H excore When using the Cartesian type, the Only H excore option enables y ou t o pr event the aut oma tic cr eation of the t etrahedr al mesh af ter he xcore gener ation (see Figur e 17.5: Only H excore (p.421)). However, the Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 420Gener ating the H excore Meshtetrahedr al mesh domain is cr eated and ac tivated dur ing the he xcore meshing pr ocedur e.You c an manually cr eate the t etrahedr al mesh in a separ ate step. Figur e 17.5: Only H excore Hex cell islands ma y be created when the Only H excore option is used .You c an delet e small islands which ma y be created b y setting the minimum allo wable siz e for the he x cell islands using the c ommand /mesh/hexcore/controls/post-relative-island-count .This c ommand is a vailable only when the Only H excore option has b een enabled in the Hexcore dialo g box.You c an also use the command /mesh/hexcore/controls/only-hexcore? to enable only he xcore meshing . The default v alue f or post-relative-island-count is 10. All he x cell islands whose siz e is less than the sp ecified p ercentage (in the default c ase, 10%) of the lar gest he x cell z one will b e aut oma tically delet ed. No islands will b e remo ved if y ou set the v alue t o 0. Note This option is not a vailable f or objec t-based v olume meshing . Warning You ma y need t o verify tha t he x cells ar e created only in the domain of in terest as the mesher c annot iden tify whether the c ells ar e within the domain without t etrahedr al meshing . Also, all the non-fluid t ype zones ar e created as separ ate fluid z ones .You need to retain the fluid z ones of in terest and delet e the others . 421Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Controlling H excore Paramet ers17.3.6. Local Refinemen t Regions When using the Cartesian type, you c an use lo cal refinemen t regions t o refine sp ecific c ells within the domain. During the he xcore meshing pr ocedur e, the c ells within the ac tivated lo cal refinemen t regions will b e refined . Currently, the only p ossible r egion shap e is a b ox, either aligned with the c o- ordina te ax es, or or iented as r equir ed. The r egion e xtents ar e defined b y the c enter and the length of the r egion. The c ell siz e within the r egion can b e manipula ted b y setting the le vel of r efinemen t relative to the maximum c ell length in the hexcore domain. You c an also or ient the r egion as r equir ed.You c an cr eate multiple r egions tha t overlap each other and the geometr y.To cr eate additional r egions , you c an c opy an e xisting r egion and then mo dify the par amet ers as r equir ed.The default r egion includes the en tire geometr y. You c an use the Draw butt on in the Hexcore Refinemen t Region dialo g box to displa y the defined region. Figur e 17.6: Local Refinemen t Region f or the H excore M esh (p.422) sho ws a r efinemen t region defined . A sample C artesian c ell with the sp ecified Max L ength is also displa yed a t the c enter of the refinemen t box. Figur e 17.6: Local Refinemen t Region f or the H excore M esh Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 422Gener ating the H excore MeshChapt er 18: Gener ating P olyhedr al M eshes Polyhedr al meshes c ontain p olyhedr al cells. An ad vantage tha t polyhedr al meshes ha ve sho wn r elative to tetrahedr al or h ybrid meshes is the lo wer o verall c ell c oun t, almost 3-5 times lo wer for unstr uctured meshes than the or iginal c ell c oun t. Since the p olyhedr al mesh has a lo wer cell c oun t than the equiv alen t original t etrahedr al mesh, solution c onvergenc e will gener ally b e fast er, possibly sa ving some c ompu- tational e xpense . Polyhedr al meshes c an b e gener ated using the objec t-based v olume meshing appr oach. The star ting point is a v alid sur face mesh (see Surface M esh P rocesses (p.239)). Prerequisit es for gener ating a p olyhedr al mesh include: •A valid sur face mesh must b e a tr iangular mesh of go od qualit y. •Surface triangula tion siz e should not e xceed ma terial thick ness . •The asp ect ratio of pr isms should b e less than 50. Note The p olyhedr al meshing pr ocess changes tr iangle fac es in the sur face mesh t o he xagonal faces. Onc e the p olyhedr al mesh e xists , you c annot r egener ate the v olume mesh unless y ou first selec t the Rest ore Faces option. When y ou selec t Rest ore Faces, the cur rent objec t face zones and c ell z ones ar e delet ed.You c an then b egin the v olume meshing pr ocess again using the or iginal v alid sur face mesh as the star ting p oint. See Gener ating the Volume Mesh (p.268) for mor e inf ormation ab out Rest ore Faces. The pr ocess f ollowed and st eps r equir ed t o gener ate the p olyhedr al mesh ar e explained . 18.1. Meshing P rocess f or P olyhedr al M eshes 18.2. Steps f or C reating the P olyhedr al M esh 18.1. Meshing P rocess f or P olyhedr al M eshes The Auto M esh dialo g box contains options f or setting up and gener ating a p olyhedr al mesh fr om a valid sur face mesh f or all c omput ed v olumetr ic regions of the mesh objec t. •If enabled , the pr ism mesh is gener ated based on the scoped prism settings sp ecified . Polyhedr al meshing does not supp ort zone-sp ecific pr isms . •The p olyhedr al meshing pr ocess star ts by gener ating a t etrahedr al mesh in t wo stages: initializa tion and refinemen t. –The aut oma tic initializa tion pr ocedur e includes the f ollowing st eps: 1.Merging fr ee no des. 423Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.2.Deleting unused no des. 3.Impr oving the sur face mesh based on p olyhedr a-dr iven cr iteria. 4.Initializing the mesh. 5.Gener ating and separ ating c ell regions . The c ell z ones ar e then asso ciated with the r egions and the c ell z one t ype will b e applied . Dead cell z ones will b e delet ed. –The r efinemen t procedur e includes the f ollowing st eps: 1.Inser ting no des f or refining the mesh. 2.Two stages of t et mesh impr ovemen t. •The p olyhedr al mesh is cr eated as a dual of the t etrahedr al mesh, such tha t the v ertex of the mesh-elemen t (tetrahedr on) is close t o the c enter of the solv er-elemen t (polyhedr on). Tessella tions ar e created f or the boundar y and c ell z ones .When pr ism mesh is gener ated, the dual is used dir ectly, meaning the la yering structure of the mesh is main tained . •The p olyhedr al mesh is impr oved b y op erations lik e mer ging shor t edges and splitting c ells. Concave cells, concave boundar y fac es, and stair-st epp ed p oly c ells ar e split t o impr ove qualit y.The qualit y is fur ther im- proved b y smo othing . The b est qualit y measur es for p olyhedr al meshing ar e squish and or tho sk ew. If you selec t squish or ortho sk ew, skewness e valua tions dur ing smo othing will b e supplemen ted with additional in ternal measur es. If you selec t a qualit y measur e other than squish or or tho sk ew, mesh gener ation will use an in ternal v ariant of squish b ecause it pr ovides some dir ect control o ver the c onvexity of the c ell. 18.2. Steps f or C reating the P olyhedr al M esh The Auto M esh dialo g box contains options t o control the p olyhedr al volume mesh gener ation. You c an gener ate the p oly mesh as f ollows: 1. Open the Auto M esh dialo g box from the c ontext-sensitiv e menu a vailable b y right-click ing on an y mesh objec t or its Volumetr ic Regions or Cell Z ones branch in the tr ee. You c an also use the Mesh → Auto M esh menu it em t o op en the Auto M esh dialo g box. 2. Ensur e tha t the mesh objec t is selec ted in the Objec t drop-do wn list. Note If you op en the Auto M esh dialo g box from the c ontext-sensitiv e menu in the tr ee, the Mesh O bjec t to which the c ell z ones or v olumetr ic regions b elong is aut oma tically selec- ted. 3. Enable/disable the Keep S olid C ell Z ones option, as appr opriate. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 424Gener ating P olyhedr al M eshes4. Selec t the appr opriate option in the Grow P risms drop-do wn list in the Boundar y Layer M esh group box. a. Retain the default selec tion of none if you do not need t o gr ow pr ism la yers f or the cur rent meshing appr oach. b.Selec t scoped if you w ant to sp ecify objec t-based pr ism c ontrols. Click Set... to op en the Scoped Prisms dialo g box and define the pr ism c ontrols f or the mesh objec t. Refer to Prism M eshing Options for Sc oped P risms (p.393) for details . Tip You c an sa ve your sc oped pr ism c ontrols t o a file (*.p zmc ontrol) f or use in ba tch mode, or r ead in a pr eviously sa ved sc oped pr ism file . Note •Poly meshing do es not supp ort zone-sp ecific pr isms . •Stair-st epping will o ccur in r egions of tr ansition b etween the pr ism la yers and the adja- cent tets. 5. Set the Poly mesh par amet ers. Selec t the Poly option fr om the Volume F ill list and set the f ollowing Volume F ill Options . •Selec t the appr opriate option f or Cell S izing . –Size Field specifies tha t the c ell siz e is det ermined based on the cur rent siz e-field . –Geometr ic specifies tha t the c ell siz e in the in terior of the domain is obtained b y a geometr ic gr owth from the closest b oundar y acc ording t o the gr owth r ate sp ecified . Set the Growth R ate requir ed. •Specify the Max C ell L ength . Click Comput e to comput e the maximum c ell siz e based on the mesh objec t. Note You c an also set these par amet ers in the Poly dialo g box. Click the Set... butt on t o op en the Poly dialo g box. a. Selec t the options in the Options group b ox. The Merge F ree N odes,Delet e Unused N odes, and Impr ove Poly M esh options ar e enabled by default. You c an also include impr oving the sur face mesh b y enabling the Impr ove Surface Mesh option. 425Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Steps f or C reating the P olyhedr al M eshb.Specify an appr opriate value f or Feature Angle .This sets the thr eshold f or pr eser ving f eatures.The default setting is 30 degr ees. c.Selec t the appr opriate cell z one t ype from the Non-F luid Type list in the Poly Z ones group b ox. Note Dead c ell z ones will b e aut oma tically delet ed af ter the mesh is initializ ed. When the initial mesh is gener ated, all the c ells ar e gr oup ed in to contiguous z ones separ ated by boundar ies.The mesh is c onsider ed t o contain a single fluid z one and one or mor e dead regions .The z one just inside the out er b oundar y is set t o be ac tive and is lab eled a fluid z one . All other non-fluid z ones will b e inac tive. Only ac tive zones will b e consider ed f or refinemen t during the mesh gener ation pr ocess. Note Volume r egion t ype is used t o det ermine the c ell z one t ype. You c an r efine diff erent groups of z ones using diff erent refinemen t par amet ers f or each gr oup by toggling the z ones b etween ac tive and inac tive. If ho wever, you need t o use the same r e- finemen t par amet ers f or all the z ones , you c an change the sp ecific ation of Non-F luid Type to a t ype other than dead (for e xample ,solid ).When the Non-F luid Type is set t o a t ype other than dead , all the z ones will b e ac tivated af ter initializa tion. Hence, you c an set the ap- propriate refinemen t par amet ers without setting all the z ones t o be ac tive. d.In most c ases , the default no de spacing thr eshold should b e acc eptable . If you w ant to change it , click Controls to op en the Poly Init C ontrols dialo g box wher e you c an mo dify the v alue . e.Set p oly c ell gr owth par amet ers using the options in the Cell S ize group b ox. Specify appr opriate values f or Max C ell Volume and Growth R ate.You c an use the Comput e butt on t o det ermine the maximum c ell siz e based on the siz e field . Ensur e tha t cells in the in terior ar e not lar ger than the siz e requir ed b y selec ting the appr opriate option in the Cell S izing list: geometr ic specifies tha t the c ell siz e in the in terior of the domain is obtained b y a geometr ic gr owth fr om the closest b oundar y acc ording t o the gr owth r ate sp ecified . size-field specifies tha t the c ell siz e is det ermined based on the cur rent siz e-field . f. Click the Local Regions butt on t o acc ess the Tet Refinemen t Region dialo g box, wher e you c an setup and ac tivate local tetrahedr al refinemen t regions .These r egions ar e used dur ing the initial tetrahedr al mesh gener ation; the y are not dir ectly applic able t o the p oly mesh. The numb er of ac tiv- ated r egions will b e reported in the Message field . 6. Retur n to the Auto M esh dialo g box and enable or disable additional Options as desir ed. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 426Gener ating P olyhedr al M eshes• Enable Merge C ell Z ones within Regions to create a single c ell z one within a r egion, or disable t o keep the c ell z ones separ ate. 7. Click Mesh in the Auto M esh dialo g box. 18.2.1. Further M esh Impr ovemen ts Examine the f ollowing af ter completing the aut oma tic mesh gener ation pr ocess: •The mesh siz e with the Rep ort Mesh S ize dialo g box (see also Determining M esh S tatistics (p.491)). •The pr ism la yer cell qualit y distr ibution (see Determining B oundar y Cell Q ualit y (p.494)). •The p olyhedr al cell qualit y reports (see Determining Volume M esh Q ualit y (p.493)). Note The qualit y measur e will b e set t o Inverse Or tho gonal Q ualit y after the p olyhedr al mesh is gener ated. 18.2.2. Transf erring the P oly M esh t o Solution M ode Node w eigh ts for no de-based gr adien ts ar e enabled b y default f or p oly meshes gener ated in F luen t Meshing .This setting c an impr ove the accur acy of the displa yed r esults near w all edges when y ou ar e displa ying c ontours on a na tive poly mesh. When y ou tr ansf er the p oly mesh t o solution mo de, a message will notify y ou tha t this in terpolation is enabled .You c an disable it b y setting the /display/set/nodewt-based-interp? command to no. 427Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Steps f or C reating the P olyhedr al M eshRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 428Chapt er 19: Gener ating P oly-H excore M eshes Poly-he xcore meshes c ontain p olyhedr al and he xcore cells.Therefore, the p oly-he xcore mesh char acter- istics c ontains elemen ts of b oth t ypes of meshes . For mor e inf ormation ab out p olyhedr a meshes , see Gener ating P olyhedr al M eshes (p.423). Likewise , for mor e inf ormation ab out he xcore meshes , see Gen- erating the H excore M esh (p.413). 19.1. Steps f or C reating the P oly-H excore Mesh 19.1. Steps f or C reating the P oly-H excore M esh The Auto M esh dialo g box contains options t o control the p oly-he xcore volume mesh gener ation. You c an gener ate the p oly-he xcore mesh as f ollows: 1. Open the Auto M esh dialo g box from the c ontext-sensitiv e menu a vailable b y right-click ing on an y mesh objec t or its Volumetr ic Regions or Cell Z ones branch in the tr ee. You c an also use the Mesh → Auto M esh menu it em t o op en the Auto M esh dialo g box. 2. Ensur e tha t the mesh objec t is selec ted in the Objec t drop-do wn list. Note If you op en the Auto M esh dialo g box from the c ontext-sensitiv e menu in the tr ee, the Mesh O bjec t to which the c ell z ones or v olumetr ic regions b elong is aut oma tically selec- ted. 3. Enable/disable the Keep S olid C ell Z ones option, as appr opriate. 4. Selec t the appr opriate option in the Grow P risms drop-do wn list in the Boundar y Layer M esh group box. a. Retain the default selec tion of none if you do not need t o gr ow pr ism la yers f or the cur rent meshing appr oach. b.Selec t scoped if you w ant to sp ecify objec t-based pr ism c ontrols. Click Set... to op en the Scoped Prisms dialo g box and define the pr ism c ontrols f or the mesh objec t. Refer to Prism M eshing Options for Sc oped P risms (p.393) for details . Tip You c an sa ve your sc oped pr ism c ontrols t o a file (*.p zmc ontrol) f or use in ba tch mode, or r ead in a pr eviously sa ved sc oped pr ism file . 429Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.5. Set the Poly-H excore mesh par amet ers. Selec t the Poly-H excore option fr om the Volume F ill list and set the f ollowing Volume F ill Options . •Specify the numb er of Buff er L ayers and Peel L ayers for the p oly-he xcore mesh. •Specify the Min C ell L ength . Click Comput e to comput e the maximum c ell siz e based on the mesh objec t. Click the Set... butt on t o op en the Poly-H excore Controls dialo g box. a. Selec t the Avoid 1:8 C ell Jump in H excore option t o elimina te the 1:8 c ell tr ansition tha t can o ccur in the he xcore region. When enabled , use the Replac e (With P olyhedr a) drop-do wn menu t o selec t whether just lar ge c ells, just small c ells, or if b oth t ypes of c ells ar e to be replac ed with p olyhedr a cells in the he xcore transition. You c an also use the c orresponding t ext command:mesh/poly-hexcore/con- trols/avoid-1:8-cell-jump-in-hexcore . b.Selec t the Mark Core Region C ell Type as H ex to ha ve only he xcore cells within the c ore of the volume mesh. You c an also use the c orresponding t ext command:mesh/poly-hexcore/con- trols/mark-core-region-cell-type-as-hex? .The default v alue is yes . c.Selec t the Only P olyhedr a for S elec ted Regions to assign p olyhedr a only t o selec tive regions .This option is a vailable only if y ou ha ve first c omput ed y our r egion(s). Onc e this option is enabled , you need t o cho ose a sp ecific r egion. For Selec t Regions (L argest Region E xcluded) , you c an cho ose fluid-r egion ,solid-r egion , or other (Fluen t aut oma tically excludes the lar gest r egion fr om the listing of a vailable r egions t o cho ose). When y ou cho ose other , the Selec ted Regions field is a vailable so tha t you c an sp ecify one or mor e regions . Enter the r egion name(s), or use the ... butt on t o op en the Volume Sc ope dialo g. In the Volume Sc ope dialo g, you c an selec t one or mor e regions , using the Draw butt on t o visualiz e the r egions pr ior t o selec tion. Onc e you ha ve selec ted y our r egion(s), click OK, and those selec tions will b e displa yed as Selec ted Regions in the Poly H excore Controls dialo g. You c an also use the c orresponding t ext command:mesh/poly-hexcore/con- trols/only-polyhedra-for-selected-regions . For e xample: Meshing/mesh/poly-hexcore/controls> only-polyhedra-for-selected-regions Mesh object [""] cyl* only-polyhedra-for-selected-regions? [yes] yes Select regions: [other]> all-fluid-regions other Select regions: [other]> other Use the following list and enter a valid region name for the mesh object "cylinder" (Largest Region Excluded). (cylinder:1 cylinder) Region name [""] "cylinder" Region name [""] Meshing/mesh/poly-hexcore/controls> Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 430Gener ating P oly-H excore Meshes6. Retur n to the Auto M esh dialo g box and enable or disable additional Options as desir ed. • Enable Merge C ell Z ones within Regions to create a single c ell z one within a r egion, or disable t o keep the c ell z ones separ ate. 7. Click Mesh in the Auto M esh dialo g box. 431Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Steps f or C reating the P oly-H excore MeshRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 432Chapt er 20: Gener ating the C utC ell M esh CutCell meshing is a gener al pur pose he x-dominan t meshing t echnique .The C utCell meshing algor ithm is suitable f or a lar ge r ange of applic ations , and due t o the lar ge fr action of he x cells in the mesh, often produces b etter results than r egular t etrahedr al meshes .This metho d can b e used inst ead of t etrahedr al or he xcore meshing , without r equir ing a v ery high qualit y sur face mesh as a star ting p oint. Also, this metho d uses a dir ect sur face and v olume appr oach without the need of cleanup or dec omp osition, ther eby reducing the tur naround time r equir ed f or meshing . The f ollowing sec tions ar e descr ibed in this chapt er: 20.1. The C utCell M eshing P rocess 20.2. Using the C utCell D ialog Box 20.3. Impr oving the C utCell M esh 20.4. Post C utCell M esh G ener ation C leanup 20.5. Gener ating P risms f or the C utCell M esh 20.6. The C ut-T et Workflow 20.1. The C utC ell M eshing P rocess The C utCell meshing pr ocess in volves the f ollowing appr oach: 1.Objec ts, material p oints (optional), and siz e func tions ar e defined . 2.The initial siz e of the C artesian gr id is c omput ed based on the minimum and maximum siz e set f or the siz e func tions . 3.A unif orm C artesian gr id is cr eated within the b ounding b ox for the geometr y. The base siz e for the C artesian gr id is c omput ed fr om the minimum and maximum siz e sp ecified in the Size Func tions dialo g box as f ollows: Base S ize = 2n × M in S ize such tha t Base S ize ≤ Max S ize 433Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.wher e n is the numb er of r efinemen t levels. Note You should main tain the r atio b etween the base siz e and the global minimum siz e such that Base S ize = 2n × M in S ize.This ensur es tha t the c orrect minimum siz e is used dur ing the C utCell meshing . Warning During initializa tion, the C artesian gr id cr eated will c ontain the maximum numb er of Cartesian c ells p ossible f or the c omput ed base siz e. If the c ell c oun t of the initial C artesian grid e xceeds the limit , use the c ommand /mesh/cutcell/set/max-initial- cells to set a mor e appr opriate numb er. 4.The siz e func tion v alues ar e comput ed and the gr id is then adaptiv ely r efined based on the lo cal siz e func tion v alues . Figur e 20.1: Schema tic R epresen tation of the C artesian G rid R efinemen t Using S ize Functions (p.434) shows a schema tic r epresen tation of the r efinemen t using siz e func tions .The siz e sour ce sp ecified via the siz e func tions will b e assimila ted in to the siz e func tion o ctree.The final mesh a t respective locations will r eflec t an in terpolated siz e based on the siz e func tions . Figur e 20.1: Schema tic Repr esen tation of the C artesian G rid Refinemen t Using S ize Func tions Figur e 20.2: Mesh A fter R efinemen t (p.435) sho ws the mesh af ter refining the initial gr id based on size func tions . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 434Gener ating the C utCell M eshFigur e 20.2: Mesh A fter Refinemen t 5.The c ells in tersec ted b y the geometr y are mar ked. Only no des on mar ked c ells ar e consider ed f or pr ojec tion. The no des ar e pr ojec ted t o the geometr y (corner, edge , and fac e in or der of r educing pr iority). Figur e 20.3: Mesh A fter P rojec tion (p.435) sho ws the mesh af ter no de pr ojec tion. Figur e 20.3: Mesh A fter P rojec tion 435Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.The C utCell M eshing P rocess6.The edges in tersec ted b y the geometr y are iden tified . Mesh edges t o be pr eser ved/r ecovered ar e det ermined , and ar e used t o constr uct mesh fac es. Onc e the mesh fac es ar e iden tified , cells ar e dec omp osed t o recover these fac es.The c ells ar e dec omp osed based on a numb er of t empla tes. Note The C utCell mesher ma y ha ve pr oblems c aptur ing f eatures lik e acut e in ternal and e xternal face angles (f or e xample , trailing edges of fins , wheel-gr ound in tersec tions). If such f eatures are not r ecovered pr operly, the pr isms gener ated a t such lo cations ar e most lik ely t o have bad qualit y. In such c ases , you c an use the set-thin-cut-edge-zones command (see Resolving Thin R egions (p.441)) and sp ecify the edges wher e the f eature captur ing fails , and then regener ate the mesh. The qualit y of the c ells thus gener ated is impr oved. 7.You c an set the default par amet ers t o be used f or impr oving the C utCell mesh using the c ommand /mesh/cutcell/set/set-post-snap-parameters .This c ommand sets the qualit y limits and other par amet ers r elevant to the no de mo vemen t and c avity remeshing tha t are performed t o impr ove qualit y. 8.Cells ar e separ ated in to cell z ones based on the r espective objec ts and ma terial p oints (if an y).When a c ell has a v ertex tha t lies out of the objec t while the other lies within the objec t, the c ell will b e dec omp osed further t o represen t the b oundar y crossing the c ell. A cell included in multiple objec ts will b e included with the objec t ha ving the highest pr iority. Figur e 20.4: Cells S epar ated A fter D ecomp osition (p.436) sho ws the c ells separ ated in to respective cell z ones af ter dec omp osition. Figur e 20.4: Cells S epar ated A fter D ecomp osition 9.Dead z ones ar e gener ally delet ed (auto-delete-dead-zones? is enabled b y default). Solid z ones will be retained or delet ed, dep ending on the setting of auto-delete-solid-zones? (disabled b y default). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 436Gener ating the C utCell M esh10.The b oundar y mesh is r ecovered and separ ated based on the under lying geometr y. •Faces whose adjac ent neighb oring c ells ar e in diff erent cell z ones aut oma tically c onstitut e the b oundar y mesh. •The neighb oring c ells of a fac e on an in ternal baffle ar e in the same c ell z one . In such c ases , faces close to and near ly par allel t o the baffle sur face are recovered t o represen t the baffle sur face. •As each c ell z one is a closed r egion, the mesh b oundar y is c onformal. The b oundar y zone t ypes ar e assigned based on the under lying geometr y zone t ype.Figur e 20.5: Cut- Cell M esh A fter B oundar y Recovery (p.437) sho ws the C utCell mesh af ter the b oundar y mesh is r e- covered. Note The C utCell mesher will assign the t ype wall on the sur face recovered o ver a geometr y zone of the t ype internal (for e xample , baffles) and the t ype geometr y. Figur e 20.5: CutC ell M esh A fter B oundar y Rec overy 437Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.The C utCell M eshing P rocess20.2. Using the C utC ell D ialo g Box The CutC ell dialo g box and the c ommands in the /mesh/cutcell menu enable y ou t o perform various tasks r elated t o gener ating the C utCell mesh. You c an use Create in the CutC ell dialo g box to gener ate the C utCell mesh based on the objec ts and material p oints selec ted. The gener ic pr ocedur e for gener ating the C utCell mesh is as f ollows: 1. Define the objec ts. a. Right click on Model in the Outline View and selec t Objec t Managemen t... to op en the Manage Objec ts dialo g box. See Using the M anage O bjec ts D ialog Box (p.232). b.Make sur e the objec ts ar e appr opriately defined (see Objec t Attribut es (p.224) for details). c.Create capping sur faces if r equir ed (see Patching Tools (p.242) for details). Imp ortant The objec ts defined include the c orresponding edges tha t are used f or c aptur ing f eatures during the C utCell mesh gener ation. If you ar e star ting fr om an ear lier setup , you ma y need t o add the appr opriate edge z ones t o the objec t before pr oceeding . Several options for cr eating the Edge Z ones are descr ibed in Extract Edge Z ones (p.327). 2. Define the ma terial p oints, if needed . a. Right click on Model in the Outline View and selec t Material P oints... to op en the Material P oints dialo g box. b.Make sur e the ma terial p oints ar e appr opriately defined (see Creating M aterial P oints (p.237) for details). 3. Define the siz e func tions as appr opriate (see Defining S ize Functions (p.215) for details). a. Right click on Model in the Outline View and selec t Func tions from the Sizing context menu t o open the Size Func tions dialo g box. b.Make sur e the siz e func tions ar e appr opriately defined . 4. Selec t the objec ts and ma terial p oints to be used f or the C utCell mesh gener ation in the CutC ell dialo g box. a. From the Mesh menu , selec t Cutcell... to op en the CutC ell dialo g box. b.Selec t the appr opriate objec ts in the Objec ts selec tion list. c.Selec t the appr opriate ma terial p oints in the Material p oints selec tion list. d.Enable Keep S olids C ell Z ones in the Options group b ox, if requir ed. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 438Gener ating the C utCell M esh5. Click Create in the CutC ell dialo g box. The fac e zones ar e separ ated b y cell neighb or and nor mals on fac e zones c onnec ted t o the fluid cell z ones ar e or iented in to the fluid z one . A fac e zone gr oup is cr eated f or the fac e zones of each fluid c ell z one . Additionally , the defaults f or p ost v olume mesh pr ism gener ation will b e set (see Gener ating P risms f or the C utCell M esh (p.443) for details). 6. Right click on Model in the Outline View and selec t Prepar e for S olve. Operations such as deleting dead z ones , deleting geometr y objec ts, deleting edge z ones , remo ving face/cell z one name pr efixes and/or suffix es, deleting unused fac es and no des ar e performed dur ing the cleanup op eration. 7. Gener ate pr ism la yers, if requir ed. a. Click Create Prisms ... to op en the Prisms dialo g box. b.Examine the fac e zone gr oup cr eated f or the fac e zones of the fluid c ell z ones and det ermine the face zones f or which pr ism meshing par amet ers ar e to be sp ecified . c.Specify the pr ism meshing par amet ers as appr opriate and click Apply . d.Click Create in the Prisms dialo g box. 8. Verify the qualit y of the C utCell mesh and p erform qualit y impr ovemen t op erations , if requir ed. Note Use the File → Write → Case... menu it em with the Write As Polyhedr a option enabled t o write the c ase file in the f ormat tha t can b e read in solution mo de in F luen t. 20.2.1. Handling Z ero-Thick ness Walls Certain geometr ies ma y ha ve comp onen ts tha t ha ve zero-thick ness . Such c onfigur ations c an b e handled during the C utCell meshing pr ocess.There ar e two types of z ero-thick ness w alls: •Baffles (z ero-thick ness w alls ha ving the same fluid/solid z one on either side) •Interior w alls (z ero-thick ness w alls ha ving diff erent fluid/solid z ones on either side) To allo w the r ecovery of baffles , any such sur face must b e of the t ype internal, which will b e recovered as a wall. For jump c onditions , the sur face must b e of one of the t ypes fan,radia tor, or porous-jump , which will b e recovered based on the t ype defined . All such sur faces should b e included in the objec t defined . If not , the sur face will not b e recovered. The r ecovered sur face for the z ero-thick ness baffles will b e pr efixed b y cutcell-t wo-sided in the gen- erated C utCell mesh. Figur e 20.6: Mesh G ener ated f or G eometr y Ha ving Z ero-Thick ness B affles (p.440) sho ws an e xample wher e the C utCell mesh has b een gener ated f or a stir rer geometr y ha ving z ero-thick ness baffles . 439Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the C utCell D ialog BoxFigur e 20.6: Mesh G ener ated f or G eometr y Having Z ero-Thick ness B affles For in terior w alls, you c an define t wo objec ts, each including the z ones c ompr ising the r espective domains . Hence, the in terior w all will app ear in b oth objec ts defined , and will b e recovered pr operly. 20.2.2. Handling O verlapping S urfaces Overlapping sur faces ar e sur faces fr om indep enden tly defined objec ts which par tially or fully o verlap. To allo w the r ecovery of o verlapping sur faces as a separ ate sur face, the o verlapping w alls must b e included in b oth defined objec ts.The distanc e between such sur faces must b e at least t en times smaller than the minimum siz e set t o avoid “trapp ed" c ell z ones .The o verlapping sur face will b e included with the r ecovered b oundar y from the objec t ha ving a higher pr iority value . Figur e 20.7: Recovering O verlapping Sur faces (p.441) sho ws an e xample wher e the C utCell mesh has been gener ated f or a butt erfly v alve.The o verlapping sur faces b etween the v alve and flo w region as well as the pip e walls and flo w region ar e recovered. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 440Gener ating the C utCell M eshFigur e 20.7: Rec overing O verlapping S urfaces 20.2.3. Resolving Thin Regions Surfaces in close pr oximit y constitut e thin r egions in the mesh. Examples of thin r egions include shar p corners , trailing edge c onfigur ations , and so on. Such c onfigur ations ma y not b e recovered accur ately enough b y the C utCell mesher , and sur face elemen ts ma y span b etween no des on the pr oximal sur faces. You c an e xplicitly define thin r egions tha t need t o be resolv ed when the C utCell mesh is gener ated. •The c ommand /mesh/cutcell/set/set-thin-cut-face-zones enables y ou t o sp ecify the face zones c onstituting the thin r egions t o be recovered. •The c ommand /mesh/cutcell/set/set-thin-cut-edge-zones enables y ou t o sp ecify edge zones defining the f eatures to be recovered in thin r egions . Figur e 20.8: Resolving Thin R egions (p.442) sho ws an e xample wher e the thin r egions ha ve been r esolv ed during the C utCell meshing pr ocess. 441Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the C utCell D ialog BoxFigur e 20.8: Resolving Thin Regions 20.3. Impr oving the C utC ell M esh The Mesh/T ools/A uto N ode M ove... menu it em op ens the Auto N ode M ove dialo g box, which y ou can use t o impr ove the C utCell mesh qualit y. The f ollowing t ext commands also enable y ou t o impr ove the C utCell mesh: /mesh/cutcell/modify/cavity-remeshing enables y ou t o use the Cavity Remeshing utilit y to impr ove the C utCell mesh qualit y near the b oundar y. Specify the c ell z ones t o be impr oved and the qualit y limit as appr opriate. For details on the options available , refer to Cavity Remeshing (p.460). Note Face zones of t ype internal are recovered as t ype wall in the cut cell mesher .These should b e reset t o type internal before using the c avity remesher . /mesh/cutcell/modify/rezone-multi-connected-faces enables y ou t o resolv e multi-c onnec ted c onfigur ations on the C utCell b oundar y. Specify an appr opriate value f or the cr itical coun t for contiguous manif old fac es. An example is sho wn in Figur e 20.9: Rezoning M ultiply C onnec ted F aces (p.443) wher e the multiply connec ted fac es ar ound the sur face ar e remo ved. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 442Gener ating the C utCell M eshFigur e 20.9: Rezoning M ultiply C onnec ted F aces 20.4. Post C utC ell M esh G ener ation C leanup After gener ating the C utCell mesh, you c an p erform cleanup op erations such as deleting dead z ones , deleting geometr y objec ts, deleting edge z ones , remo ving fac e/cell z one name pr efixes and/or suffix es, deleting unused fac es and no des.These op erations c an b e performed b y selec ting Prepar e for S olve in the c ontext menu under Model in the Outline View. Note It is r ecommended tha t you use the Delet e option in the Manage C ell Z ones dialo g box or the c ommand /mesh/manage/delete to delet e cell z ones in the C utCell mesh, inst ead of the Mesh/C lear option or the /mesh/clear-mesh command . 20.5. Gener ating P risms f or the C utC ell M esh After gener ating the C utCell mesh, the fac e zones ar e separ ated b y cell neighb or and nor mals on fac e zones c onnec ted t o the fluid c ell z ones ar e or iented in to the fluid z one . A fac e zone gr oup is cr eated for the fac e zones of each fluid c ell z one . Additionally , the defaults f or p ost v olume mesh pr ism gener- ation will b e set. These include the f ollowing pr ism c ontrols t o reduc e stair-st epping of pr ism la yers: •Disable edge sw apping . /mesh/prism/controls/improve/edge-swap? no •Disable fac e smo othing . /mesh/prism/controls/face-smooth? no •Set the sk ewness thr eshold f or edge sw apping and edge and no de smo othing t o 0.95 . /mesh/prism/controls/improve/swap-smooth-skew 0.95 •Ensur e tha t shr inkage f or pr ism la yers is enabled . /mesh/prism/controls/proximity/allow-shrinkage? yes •Set the smo othing r ate (rate at which shr inkage is pr opaga ted la terally) t o 1.2 . 443Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Gener ating P risms f or the C utCell M esh/mesh/prism/controls/proximity/smoothing-rate 1.2 •Disable ignor ing of no des tha t ha ve poor nor mals . /mesh/prism/controls/normal/ignore-invalid-normals? no •Set the c ell qualit y criterion f or smo othing and qualit y check ing t o 0.999 . /mesh/prism/controls/improve/max-allowable-cell-skew 0.999 •Enable smo othing of nor mals along the f eature lines of the base fac e zones . /mesh/prism/controls/improve/identify-feature-line? yes •Set the maximum allo wable sk ewness f or cap fac es af ter smo othing t o 0.999 . /mesh/prism/controls/improve/max-allowable-cap-skew 0.999 •Set the qualit y metho d to Orthosk ew. /mesh/prism/quality-method orthoskew •Enable the impr ovemen t of c ell qualit y for e very pr ism la yer.This will in volve smo othing of nor mals in the current layer and p erturba tion smo othing t o impr ove cell qualit y in the lo wer la yer. /mesh/prism/controls/improve/cell-quality-improve? yes •Enable the adjustmen t of pr ism heigh ts at prism c ap c orners t o impr ove cell qualit y. /mesh/prism/controls/improve/corner-height-weight? yes •Disable f orcible smo othing of c ells if c ell qualit y remains bad af ter regular smo othing . /mesh/prism/improve/smooth-brute-force? no You c an gener ate pr ism la yers on the appr opriate fac e zones as f ollows: 1. Click Create Prisms ... in the CutC ell dialo g box to op en the Prisms dialo g box. 2. Examine the fac e zone gr oup cr eated f or the fac e zones of the fluid c ell z ones and det ermine the fac e zones f or which pr ism meshing par amet ers ar e to be sp ecified . 3. Specify the pr ism meshing par amet ers as appr opriate and click Apply . Note Hanging-no de c ells on a b oundar y for which pr ism gener ation has b een assigned , will be triangula ted b efore the pr ism gener ation star ts. Imp ortant Attempting t o gr ow thick er pr ism la yers in ar eas wher e the asp ect ratio of the base t o the pr ism c ap is v ery lar ge ma y result in an in valid mesh. In such c ases , (for e xample , Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 444Gener ating the C utCell M eshexternal flo w pr oblems) it is r ecommended tha t asp ect ratio based gr owth b e used t o avoid pr oblems with in valid meshes . 4. Click Create in the Prisms dialo g box. As the v olume mesh alr eady exists , a Question dialo g box will app ear, ask ing if y ou w ant to mor ph the e xisting v olume mesh. Click Yes to gener ate the pr ism la yers. Alternatively, use the c ommand /mesh/cutcell/create-prism to cr eate the pr ism la yers. Specify the c ell z ones in to which the pr ism la yers ar e to be gr own. The gap fac tor c ontrols the numb er of elemen ts in r egions of pr oximit y. Note If the c ell asp ect ratio e xceeds the sp ecified maximum asp ect ratio, a message will app ear during the pr ism meshing pr ocess, indic ating tha t shr inkage w as limit ed b y the maximum aspect ratio sp ecified . You c ould also r educ e the gap fac tor to avoid the c ell asp ect ratio e xceeding the sp ecified maximum asp ect ratio. Reducing the gap fac tor (f or e xample , a value of 0.5) ma y impr ove the qualit y, but c ould ha ve a nega tive impac t on the r obustness of the mor phing . A higher v alue (f or e xample , 1.5) is gener ally mor e robust , but ma y not r esult in the b est mesh qualit y. Note During the sur face mesh mor phing , only the b oundar ies of fac e thr eads will b e treated as features. When pr ism la yers ar e gr own in to cell z ones shar ing a fac e, the pr isms will b e impr inted on the shar ed fac e. Figur e 20.10: Gener ating P risms f or the C utCell M esh (p.445) sho ws the pr ism la yers cr eated f or the CutCell mesh. The pr ism la yers will b e compr essed in r egions of pr oximit y and bad nor mals . Note that local stair-st epping ma y occur in ar eas of p oor qualit y. Figur e 20.10: Gener ating P risms f or the C utC ell M esh 445Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Gener ating P risms f or the C utCell M esh•When pr ism la yers ar e gr own in to two volumes shar ing an edge , stair-st epping will o ccur a t the c ommon vertex between the v olumes ( Figur e 20.11: Prism G rowth Limita tions—V olumes S haring an E dge (p.446)). Figur e 20.11: Prism G rowth Limita tions—V olumes S haring an E dge •When pr ism la yers ar e gr own in to two volumes shar ing an edge , stair-st epping will o ccur a t the no des on the c ommon b oundar y (Figur e 20.12: Prism G rowth Limita tions—V olumes S haring an E dge (p.446)). Figur e 20.12: Prism G rowth Limita tions—V olumes S haring an E dge •Prism la yers c annot b e gr own on b oth sides of a sur face shar ed b y adjac ent volumes ( Figur e 20.13: Prism Growth Limita tions—V olumes S haring the P rism B ase (p.447)). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 446Gener ating the C utCell M eshFigur e 20.13: Prism G rowth Limita tions—V olumes S haring the P rism B ase A combina tion of no de mo vemen t and c avity remeshing is c arried out t o impr ove the C utCell mesh qualit y after the pr ism la yers ha ve been gener ated.The par amet ers f or impr oving the CutCell mesh qualit y can b e sp ecified using the c ommand /mesh/cutcell/set/set-post- morph-parameters prior t o cr eating the pr ism la yers.The qualit y metho d consider ed is tha t set b y the /mesh/cutcell/set/set-cutcell-quality-method command . 5. Ensur e tha t the qualit y of the pr isms cr eated is appr opriate. If the qualit y of the pr ism c ells is lo w, you c an use p ost-pr ism smo othing t o impr ove the qualit y. Use the options in the Prism Impr ove dialo g box or text commands such as /mesh/prism/improve/smooth-improve-prism-cells to impr ove the pr ism c ell qualit y. 6. To fur ther impr ove the C utCell mesh using the c ommand /mesh/cutcell/modify/post-morph- improve , mo dify the r elevant par amet ers using the c ommand /mesh/cutcell/set/set-post- morph-parameters .The qualit y consider ed is tha t set b y the /mesh/cutcell/set/set-cutcell- quality-method command . Note This op eration uses a c ombina tion of no de mo vemen t and c avity remeshing t o impr ove the C utCell mesh qualit y. For details on the r elevant par amet ers, refer to Moving Nodes (p.458) and Cavity Remeshing (p.460). Note It is r ecommended tha t you use the /mesh/cutcell/modify/post-morph-im- prove command f or c ell z ones other than the pr ism c ells. 447Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Gener ating P risms f or the C utCell M esh20.6. The C ut-T et Workflo w The C ut-T et w orkflow enables y ou t o cr eate a t etrahedr al, hexcore, or pr ism mesh based on a tr iangula ted and impr oved C utCell sur face mesh. The initial r equir emen t is the gener ated C utCell mesh. The gener ic w orkflow is as f ollows: 1. Make the C utCell b oundar ies c onformal t o remo ve hanging-no des. /mesh/cutcell/modify/split-boundary cutcell-* , The c ommand /mesh/cutcell/modify/split-boundary creates a c opy of the sp ecified CutCell b oundar y zones and mak es the b oundar y mesh c onformal a t the hanging-no des on the copied z ones .The new z ones will b e named based on the or iginal z one names pr efixed b y split- . 2. Clear the v olume mesh. /mesh/clear-mesh 3. Triangula te the split C utCell b oundar y zones . /boundary/remesh/triangulate split-* , yes The split C utCell b oundar y zones will b e replac ed b y the c orresponding tr iangula ted b oundar y zones . 4. Impr ove the b oundar y mesh b y sw apping edges based on a no de degr ee v alue other than 6. The no de degr ee is defined as the numb er of edges c onnec ted t o the no de. /boundary/improve/degree-swap Use b oundar y smo othing op erations t o fur ther impr ove the b oundar y mesh qualit y (see subsequen t step). Note Do not use the /boundary/improve/swap operation immedia tely af ter the /boundary/improve/degree-swap operation, as this will r estore the or iginal degr ee configur ations . 5. Impr ove the tr iangula ted b oundar y mesh fur ther using an y of the f ollowing options a vailable: a. Use wr app er smo othing op erations t o impr ove the b oundar y mesh qualit y. i. Change the t ype of the tr iangula ted b oundar y mesh t o wrapp er. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 448Gener ating the C utCell M eshii. Use the wr app er p ost impr ove op erations t o impr ove the b oundar y mesh qualit y. Refer to Dia- gnostic Tools (p.247) or Impr oving the M esh O bjec ts (p.338)for detailed descr iptions of the options available . Note Make sur e the or iginal geometr y is r etained when the C utCell mesh is gener- ated, this r equir ed f or reprojec tion when using the p ost impr ove op erations . b.Use op erations lik e impr oving based on b oundar y mesh qualit y, smo othing , and sw apping t o impr ove the b oundar y mesh qualit y. Refer to Impr oving B oundar y Sur faces (p.288) for the detailed descr iptions of the options a vailable . c.Use sur face remeshing with the siz e func tions defined f or the C utCell mesh. i. Extract edge z ones fr om the tr iangula ted b oundar y mesh. This enables y ou t o main tain the b oundar y no de lo cations on the r emeshed fac es and facilita tes the c onnec tion b etween the r emeshed fac es using simple no de mer ge op era- tions . Split the edges ha ving siz es bigger than the siz e func tion defined using the Scheme command (ti-refine-edge-threads-by-sf (get-edge-zones-of-filter 'split-*)) ii. Remesh the tr iangula ted b oundar y mesh using the defined siz e func tions using the Scheme command (ti-remesh-multiple-threads (get-face-zones-of-filter 'split- *) #f #t "none" #t) This enables y ou t o remesh multiple sur faces in a single op eration. Tip You c an also add a meshed siz e func tion on the edge z ones e xtracted fr om the tr iangula ted b oundar y mesh t o impr ove the qualit y. iii. Merge duplic ate boundar y no des on the r emeshed b oundar y zones . 6. Gener ate the t etrahedr al/he xcore/pr ism mesh. Refer to Gener ating Tetrahedr al M eshes (p.399),Gener ating the H excore Mesh (p.413), and Gener ating P risms (p.367) for the detailed descr iptions of the meshing 449Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.The C ut-T et Workflowoptions a vailable .You c an also use the Auto M esh option (see Using the A uto M esh D ialog Box (p.349)) for gener ating the mesh. Note To gener ate the t etrahedr al mesh using the defined siz e func tions , use (tgsetvar! 'impose/cell-size-method 4) .This will also r espect the b ody of influenc e siz e func tions defined f or the C utCell meshing . You c an also use additional op erations dur ing the v olume meshing pr ocess, as appr opriate. For example ,/mesh/manage/merge-dead-zones can b e used t o mer ge dead z ones ha ving a c ell coun t lower than the sp ecified thr eshold v alue , with the adjac ent cell z one . 7. Impr ove the mesh qualit y using the v arious impr ovemen t options a vailable . Refer to Impr oving the Mesh (p.451) for detailed descr iptions of the options a vailable . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 450Gener ating the C utCell M eshChapt er 21: Impr oving the M esh A volume mesh cr eated fr om a high-qualit y sur face mesh ma y contain some high-sk ewness c ells.The poor c ells ma y result fr om unsuitable mesh siz e distr ibution o ver the domain or , mor e of ten, are caused by constr aints imp osed b y the b oundar ies. After cr eating a t etrahedr al or h ybrid mesh, you c an impr ove the qualit y of the mesh b y smo othing nodes and sw apping fac es. Smoothing and fac e sw apping ar e tools tha t help t o impr ove the qualit y of the final numer ical mesh. You c an also use the impr ove command which c ombines op erations lik e collapsing c ells, node smo othing , face sw apping , and inser ting no des.This chapt er descr ibes the options available f or impr oving the mesh qualit y by remo ving highly sk ewed c ells. 21.1. Smoothing N odes 21.2. Swapping 21.3. Impr oving the M esh 21.4. Remo ving S livers fr om a Tetrahedr al M esh 21.5. Modifying C ells 21.6. Moving N odes 21.7. Cavity Remeshing 21.8. Manipula ting C ell Z ones 21.9. Manipula ting C ell Z one C onditions 21.10. Using D omains t o Group and M esh B oundar y Faces 21.11. Check ing the M esh 21.12. Selec tively C heck ing the Volume M esh 21.13. Check ing the M esh Q ualit y 21.14. Clearing the M esh 21.1. Smoothing N odes Smoothing r epositions the no des t o impr ove the mesh qualit y.The smo othing metho ds a vailable ar e: 21.1.1. Laplac e Smoothing 21.1.2. Variational S moothing of Tetrahedr al M eshes 21.1.3. Skewness-B ased S moothing of Tetrahedr al M eshes 21.1.1. Laplac e Smoothing Laplac e smo othing is used t o impr ove (reduc e) the a verage sk ewness of the mesh. In this metho d, a Laplacian smo othing op erator is applied t o the unstr uctured gr id to reposition no des.The new no de position is the a verage of the p ositions of its no de neighb ors. The r elaxa tion fac tor (a numb er b etween 0.0 and 1.0) multiplies the c omput ed no de p osition incr emen t. A value of z ero results in no mo vemen t of the no de and a v alue of unit y results in mo vemen t equiv alen t to the en tire comput ed incr emen t. This no de r epositioning str ategy impr oves the sk ewness of the mesh, but usually r elax es the clust ering of no de p oints. In e xtreme cir cumstanc es, the uncheck ed op erator ma y create gr id lines tha t cross over the b oundar y, creating nega tive cell v olumes .To pr event such cr osso vers, the sk ewness of the 451Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.resulting c ells is check ed b efore the no de is r epositioned .This mak es the smo othing op eration time- consuming . The smo othing op erator c an also b e applied r epeatedly , but as the numb er of smo othing it erations increases , the no de p oints ha ve a t endenc y to pull a way from b oundar ies and the mesh t ends t o lose any clust ering char acteristics . 21.1.2. Variational S moothing of Tetrahedr al M eshes Variational smo othing is a vailable only f or tetrahedr al meshes . It can b e consider ed as a v ariant of Laplac e smo othing .The new no de p osition is c omput ed as a w eigh ted a verage of the cir cumc enters of the c ells c ontaining the no de.The v ariational smo othing metho d is pr ovided as a c omplemen t to Laplac e smo othing . 21.1.3. Skewness-B ased S moothing of Tetrahedr al M eshes Skewness-based smo othing is a vailable only f or tetrahedr al meshes .When y ou use sk ewness-based smo othing , a smo othing op erator is applied t o the mesh, repositioning in terior no des t o lo wer the maximum sk ewness of the mesh. Interior no des will b e mo ved t o impr ove the sk ewness of c ells with skewness gr eater than the sp ecified minimum sk ewness .You c an also sp ecify an appr opriate value f or the minimum impr ovemen t, if requir ed.This allo ws you t o stop p erforming the smo othing it erations when the maximum change in c ell sk ewness is less than or equal t o the v alue sp ecified f or minimum impr ovemen t. The maximum change in c ell sk ewness will b e compar ed with the sp ecified v alue f or minimum im- provemen t.When the maximum change in c ell sk ewness is less than or equal t o the v alue sp ecified for minimum impr ovemen t, further smo othing it erations will no longer yield appr eciable impr ovemen t in the mesh. The smo othing will b e stopp ed a t this p oint even if the r equest ed numb er of it erations has not b een c omplet ed. This sk ewness-based smo othing pr ocess c an b e very time-c onsuming , so it is ad visable t o perform smo othing only on c ells with high sk ewness . Impr oved r esults c an b e obtained b y smo othing the nodes se veral times .There ar e in ternal checks tha t will pr event a no de fr om b eing mo ved if mo ving it causes the maximum sk ewness t o incr ease , but it is c ommon f or the sk ewness of some c ells t o incr ease when a c ell with a higher sk ewness is b eing impr oved. Hence, you ma y see the a verage sk ewness in- crease while the maximum sk ewness is decr easing . You should c onsider whether the impr ovemen ts to the mesh due t o a decr ease in the maximum skewness ar e worth the p otential incr ease in the a verage sk ewness . Performing smo othing only on cells with v ery high sk ewness (f or e xample , 0.8 or 0.9) ma y decr ease the ad verse eff ects on the a verage skewness . 21.2. Swapping For tetrahedr al meshes , swapping in volves sear ching f or a sp ecific c onfigur ation of c ells and r eplacing it by an alt ernative configur ation. The default option is a 3–2 sw ap c onfigur ation wher e thr ee t etrahedr a are replac ed b y two tetrahedr a after sw apping .The other p ossible c ombina tions ar e the 2–3 sw ap configur ation (r eplacing t wo tetrahedr a by thr ee) and the 4–4 sw ap c onfigur ation (r eplacing f our e xisting tetrahedr a with f our alt ernate tetrahedr a). Figur e 21.1: 2–3 and 3–2 S wap C onfigur ations (p.453) sho ws the 2–3 and 3–2 sw ap c onfigur ations .The two tetrahedr a (on the lef t) ha ving a c ommon in terior fac e can b e replac ed b y thr ee t etrahedr a ha ving Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 452Impr oving the M esha common in terior edge .The c ommon fac e will b e replac ed b y thr ee in terior fac es and an in terior edge during sw apping . Conversely , the thr ee t etrahedr a (on the r ight) ha ve two in terior fac es each and shar e a common in terior edge . During sw apping f or a 3–2 c onfigur ation, three in terior fac es and the c ommon interior edge will b e replac ed b y a single fac e.This r esults in t wo tetrahedr a ha ving a c ommon in terior face. Figur e 21.1: 2–3 and 3–2 S wap C onfigur ations Another p ossible sw ap c onfigur ation is the 4–4 sw ap c onfigur ation wher e four t etrahedr a will b e replac ed by four alt ernate tetrahedr a. In Figur e 21.2: 4–4 S wap C onfigur ation (p.453), either the c ommon in terior edge or t wo common fac es c an b e replac ed, resulting in f our alt ernate tetrahedr a. Figur e 21.2: 4–4 S wap C onfigur ation 453Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Swapping21.3. Impr oving the M esh The Impr ove operation is an aut oma ted pr ocedur e for sliv er remo val or f or reducing the maximum skewness in the mesh. The impr ovemen t is c arried out b y remo ving c ells ab ove the sp ecified sk ewness threshold b y collapsing c ells, swapping fac es, smo othing no des, and inser ting new no des it eratively. Each op eration is sp ecializ ed, and the mesh will b e mo dified only if the mesh is notic eably impr oved. The sk ewness b efore and af ter an op eration is tak en in to acc oun t to det ermine the impr ovemen t. Hence, the lo wer the sk ewness of the c ells in volved, the lar ger the impr ovemen t will ha ve to be in or der f or the mesh t o be mo dified .The impr ove op eration is a mor e elab orate version of the Remo ve Slivers option in voked fr om the Refinemen t tab in the Tet dialo g box. 21.4. Remo ving S livers fr om a Tetrahedr al M esh A sliv er typic ally denot es a fla t tetrahedr al cell.Figur e 21.3: Sliver F ormation (p.454) sho ws an acc eptable tetrahedr on. Figur e 21.3: Sliver F ormation If the t op no de of the t etrahedr on w ere to travel along the pa th of the dott ed line in the dir ection of the ar row, as it appr oached the end of the line the r esulting c ell w ould b e a degener ate tetrahedr on, or a sliv er. In the f ollowing sec tions , the t erm sliv er is used t o denot e all t ypes of p oorly shap ed c ells.There ar e several commands f or remo ving sliv ers or t o reduc e the maximum sk ewness of the mesh. 21.4.1. Automa tic S liver Remo val 21.4.2. Remo ving S livers M anually 21.4.1. Automa tic S liver Remo val Sliver remo val op erations c an b e invoked dur ing the t etrahedr al mesh r efinemen t process.The Remo ve Slivers option in the Refinemen t tab of the Tet dialo g box controls the r emo val of sliv ers dur ing the meshing pr ocess.The Remo ve Slivers option includes op erations such as c ollapsing c ells (t o remo ve nodes), face sw apping , smo othing , and p oint inser tion, which ar e invoked it eratively. Usually the sliv er cells will b e remo ved dur ing r efinemen t, but o ccasionally a f ew migh t be lef t behind . In such c ases , you c an use the options in the Slivers tab in the Tet Impr ove dialo g box to remo ve Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 454Impr oving the M eshthe sliv ers manually .The Impr ove command uses an aut oma ted pr ocedur e to remo ve sliv ers or t o impr ove the mesh qualit y in gener al. 21.4.2. Remo ving S livers M anually The Tet Impr ove dialo g box contains options f or remo ving sliv ers manually .The op erations a vailable for sliv er remo val ar e as f ollows: Smo othing B oundar y Sliv ers This op eration in volves smo othing no des on sliv er cells ha ving a t least one no de on the b oundar y. During smo othing , the no des will b e repositioned so long as the sk ewness of the sur rounding c ells is impr oved.The no des on f eatures will also b e smo othed , but will not b e pr ojec ted on t o the or iginal geometr y. However, nodes a t branch p oints (mor e than t wo feature edges a t the no de) and end p oints (one f eature edge a t the no de) will b e fix ed.The no des will b e smo othed un til the sk ewness v alue is less than the sp ecified v alue .The default v alues f or the sk ewness thr eshold , minimum dihedr al angle between b oundar y fac es, and f eature angle ar e 0.985 ,10, and 30, respectively. Smo othing Int erior Sliv ers This op eration in volves smo othing non-b oundar y no des on sliv er cells ha ving sk ewness gr eater than the sp ecified thr eshold v alue .The default v alue f or the sk ewness thr eshold is 0.985 . Swapping B oundar y Sliv ers A fla t boundar y cell c ontaining t wo boundar y fac es c an b e remo ved b y mo ving the b oundar y to exclude the c ell fr om the z one in which it is lo cated, effecting a minor change in the geometr y. However, if ther e is another liv e zone on the other side of the b oundar y, this op eration will r esult in the c ell b eing moved t o the other z one . In such c ases (f or e xample , conjuga te hea t transf er pr oblems), you c an decide which liv e zone is least cr itical, and then mo ve the b oundar y sliv er to tha t zone . The default v alues f or the sk ewness thr eshold and the minimum dihedr al angle b etween fac es ar e 0.95 and 10, respectively. Refining B oundar y Sliv ers This op eration a ttempts t o incr ease the v olume of b oundar y sliv ers t o cr eate a v alid t etrahedr al cell. Tetrahedr a ha ving one or t wo fac es on the b oundar y are iden tified and then the edge opp osite the boundar y fac es ar e split. The edge opp osite the fac e pair with the lar gest dihedr al angle will b e split for a t etrahedr on with one b oundar y fac e, while the edge opp osite the b oundar y fac es will b e split for a t etrahedr on ha ving t wo boundar y fac es.The split no de is then smo othed such tha t the v olume of the t etrahedr on incr eases , ther eby creating a v alid t etrahedr al cell. Refining Int erior Sliv ers This op eration a ttempts t o remo ve the sliv er b y placing a no de a t or near the c entroid of the sliv er cell. Swapping and smo othing ar e then p erformed t o impr ove the sk ewness . 455Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Remo ving S livers fr om a Tetrahedr al M eshCollapsing Sliv ers This op eration a ttempts t o collapse the edge of a sk ewed sliv er cell on an y one of its neighb ors.The default sk ewness thr eshold is 0.985 . Note •If you ar e not using a t wo-sided w all c ondition f or the b oundar y, you c an slit the fac e zone containing the sliv er (using the /boundary/slit-boundary-face command) and then perform the sliv er-remo val op eration. •Multiple sliv ers ma y exist on t op of each other thus , requir ing multiple op erations t o remo ve them all. 21.5. Modifying C ells Additional t ools ar e available f or y ou t o perform pr imitiv e op erations on the c ells such as smo othing nodes, swapping c ells, splitting c ells, and so on. This sec tion descr ibes the gener ic pr ocedur e for modifying the c ells using the Modify C ells dialo g box.You will also use the Displa y Grid dialo g box during the mo dific ation of the c ells. 21.5.1. Using the M odify C ells D ialog Box 21.5.1. Using the M odify C ells D ialo g Box 1.Displa y the c ells or c ell z ones t o be mo dified using the options in the Displa y Grid dialo g box. 2.Selec t the t ype of en tity (cell,face,node, and so on) y ou w ant in the Filter list in the Modify C ells dialo g box. 3.Selec t the en tity to be mo dified in the gr aphics windo w. 4.Click the appr opriate butt on in the Operation group b ox. The displa y will b e aut oma tically up dated t o reflec t the change made b y the op eration. 5.Repeat the pr ocedur e to perform diff erent op erations on the c ells. Warning Save the mesh p eriodically as not all op erations ar e reversible . The options in the Draw C ells group b ox enable dr awing of c ells using no des or fac es selec ted in the graphics windo w. •Use the Using N odes option t o displa y cells which c ontain the selec ted no des. •Use the Using F aces option t o displa y cells which c ontain the selec ted fac es. The op erations a vailable in the Modify C ells dialo g box for mo difying c ells ar e as f ollows: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 456Impr oving the M eshSmo othing N odes The selec ted no des will b e repositioned based on the a verage of the sur rounding no des dur ing no de smo othing . Selec t the no des t o be smo othed and click Smooth in the Operation group b ox to smo oth nodes. Splitting C ells The selec ted c ell will b e refined b y the addition of a no de a t the c entroid of the c ell dur ing splitting . Each c ell will b e split in to four c ells. Moving N odes You c an mo ve the selec ted no de either t o a sp ecified p osition or b y a sp ecified magnitude . Do the f ollowing t o mo ve a no de t o a par ticular p osition: 1. Selec t node in the Filter list and selec t the no de t o be mo ved. 2. Selec t position in the Filter list and selec t the appr opriate position. 3. Click Move To in the Operation group b ox. Do the f ollowing t o mo ve a no de b y a sp ecified magnitude: 1. Selec t node in the Filter list and selec t the no de t o be mo ved. 2. Enter the magnitude b y which y ou w ant to mo ve the no de in the Enter S elec tion field and pr ess Enter. The incr emen t will no w b e selec ted in the Selec tions list. 3. Click Move By in the Operation group b ox. Swapping C ells You c an p erform either a 3-2 c onfigur ation sw ap or a 2-3 c onfigur ation sw ap. Refer to Swapping (p.452) for details on the sw ap c onfigur ations . Do the f ollowing t o sw ap c ells: 1. Selec t the appr opriate option in the Filter list and selec t the en tities t o be sw app ed. •Selec t 3 c ells or the c ommon edge in or der t o perform a 3-2 sw ap. •Selec t 2 c ells or the c ommon fac e in or der t o perform a 2-3 sw ap. 2. Click Swap in the Operation group b ox. Determining the C oordinat es of the C entr oid Do the f ollowing t o det ermine the c entroid: 1.Selec t the appr opriate option in the Filter list ( cell,face,edge , or node) and selec t the r equir ed en tity. 2.Click Centroid in the Operation group b ox. 457Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modifying C ellsThe c entroid c oordina tes will b e pr inted in the c onsole . Determining the D istanc e Between E ntities Do the f ollowing t o det ermine the distanc e between en tities: 1.Selec t the appr opriate option in the Filter list and selec t the t wo en tities b etween which the distanc e is to be det ermined . 2.Click Distanc e in the Operation group b ox. The distanc e between the selec ted en tities will b e pr inted in the c onsole . Projec ting N odes You c an pr ojec t no des on to a sp ecified pr ojec tion line or plane . Do the f ollowing t o pr ojec t no des: 1.Define the pr ojec tion line or pr ojec tion plane , as appr opriate. a.Selec t the appr opriate option in the Filter list. b.Selec t two en tities t o define the pr ojec tion line or thr ee en tities t o define the pr ojec tion plane . c.Click Set in the Operation group b ox to define the pr ojec tion line or plane . The line c oordina tes or plane p osition will b e reported in the c onsole . 2.Selec t the no des t o be pr ojec ted. The pr ojec tion line/plane will b e highligh ted in the displa y windo w. 3.Click Projec t in the Operation group b ox. 21.6. Moving N odes Highly sk ewed meshes c an b e impr oved b y mo ving the no des of the c ells. Moving no des manually is a time c onsuming pr ocess.The no de mo vemen t process f or impr oving the mesh qualit y is aut oma ted. You c an sp ecify qualit y impr ovemen t based on the qualit y measur e sp ecified or based on the w arp (quadr ilateral elemen ts).You c an also cho ose b etween the aut oma tic c orrection pr ocedur e and the semiaut oma tic c orrection pr ocedur e for the qualit y-based c orrection. You c an also r epair nega tive volume c ells b y mo ving no des using the aut oma tic c orrection pr ocedur e. 21.6.1. Automa tic C orrection 21.6.2. Semi-A utoma tic C orrection 21.6.3. Repair ing N egative Volume C ells 21.6.1. Automa tic C orrection The aut oma tic c orrection allo ws you t o impr ove all the c ells in the selec ted c ell z one based on the specified cr iteria.You c an also impr ove the c ells based on the w arp values . You c an acc ess the Auto N ode M ove dialo g box using the Mesh → Tools menu; or b y right click ing on Cell Z ones or an y individual c ell z one in the tr ee. Selec ting fr om the tr ee will aut oma tically selec t the individual c ell z one or all z ones . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 458Impr oving the M eshQualit y-Based Impr ovement For the qualit y-based c orrection, you c an sp ecify the qualit y limit based on the qualit y measur e selec ted, dihedr al angle , and the numb er of it erations p er no de t o be mo ved.The c ells which ha ve a qualit y above the sp ecified thr eshold limit will b e selec ted. For b oundar y no des, you c an r estrict the no de mo vemen t in the plane c ontaining each of the boundar y fac es shar ing the no de b eing mo ved. Nodes on shar p features and fr ee edges will not b e consider ed f or mo vemen t. The no de t o be mo ved f or a par ticular c ell will b e selec ted based on the selec tion of z ones in the Boundar y Zones selec tion list and an alt ernative position f or the no de will b e det ermined .The no de will b e mo ved t o the new p osition only if the qualit y of the c ell and its neighb ors is impr oved b y the change in no de p osition. The pr ocedur e is r epeated f or the sp ecified it erations p er no de.You c an also set the numb er of r epetitions thr ough the aut oma tic c orrection pr ocedur e as r equir ed. By default , the correction pr ocedur e is p erformed only onc e. Warp-B ased Impr ovement For the w arp-based c orrection, you c an sp ecify the maximum w arp and the numb er of it erations p er face to be impr oved.The quadr ilateral fac es which ha ve a w arp value gr eater than the sp ecified max- imum w arp will b e selec ted.The ideal p osition f or the no de t o be mo ved will b e det ermined based on the r emaining thr ee no des.The no de will b e mo ved t o the new p osition only if the w arp of the face decr eases and the c ell qualit y do es not det eriorate by the change in no de p osition. The pr ocedur e is repeated f or the sp ecified it erations p er fac e.You c an also set the numb er of r epetitions thr ough the aut oma tic c orrection pr ocedur e as r equir ed. By default , the c orrection pr ocedur e is p erformed f our times . 21.6.2. Semi-A utoma tic C orrection The semi-aut oma tic c orrection is a vailable only f or qualit y-based impr ovemen t.The gener ic pr ocedur e for using the semiaut oma tic c orrection is as f ollows: 1. Selec t the appr opriate zones in the Cell Z ones drop-do wn list and the Boundar y Zones selec tion list. 2. Selec t the qualit y measur e and sp ecify v alues f or Qualit y Limit ,Iterations/N ode, and Dihedr al A ngle as appr opriate. 3. Enable Restr ict Boundar y Nodes A long S urface if requir ed.When this option is enabled , the mo vemen t of the b oundar y no de will b e limit ed t o the plane c ontaining the b oundar y fac es shar ing the b oundar y node (see Figur e 21.4: Movemen t of B oundar y Nodes (p.460)). 459Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Moving N odesFigur e 21.4: Movemen t of B oundar y Nodes 4. Click Skew to displa y the c ell with the w orst qualit y dep ending on the qualit y limit sp ecified .The c ell having the w orst qualit y and c ells/fac es within a pr e-defined r ange of the c ell will b e displa yed. 5. Click Propose.The no de t o be mo ved and the alt ernative position will b e highligh ted.The impr ovemen t in the sk ewness will also b e reported in the c onsole . 6. If the pr oposed p osition is appr opriate, click Accept; other wise , click Refuse and then Propose to obtain the ne xt suggestion. 7. Click Next Skew to pr oceed with the no de c orrection f or the ne xt cell. 21.6.3. Repair ing N ega tive Volume C ells You c an also r epair nega tive volume c ells b y mo ving no des. Specify the appr opriate boundar y zones , dihedr al angle , the numb er of it erations p er no de t o be mo ved and the numb er of it erations of the automa tic no de mo vemen t procedur e (default , 1).You c an also cho ose t o restrict the mo vemen t of boundar y no des along the sur face. 21.7. Cavity Remeshing Cavity remeshing is useful in par ametr ic studies b ecause it enables y ou add , remo ve, and r eplac e diff erent parts of the e xisting mesh. You c an c ompar e alt ernative designs b y creating a c avity around the objec t to be replac ed and then, inser ting the new objec t and c onnec ting it t o the e xisting mesh. Prisms c an be gr own using appr opriate par amet ers and the c avity can b e filled with c ells.You c an also impr ove the qualit y of the v olume mesh b y creating an appr opriate cavity around the sk ewed c ells and remeshing it. You c an cr eate a c avity in an e xisting mesh b y remo ving c ells in a defined b ounded r egion. The c ells intersec ting the b ounded r egion will b e mar ked and the c avity boundar ies will b e extracted fr om the mar ked c ells.The mar ked c ells will then b e delet ed t o cr eate the c avity. The v arious options a vailable ar e: •Remo ving z ones: This option allo ws you t o sp ecify z ones t o be remo ved fr om the e xisting v olume mesh. •Adding z ones: This option allo ws you t o add new z ones t o the e xisting v olume mesh. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 460Impr oving the M esh•Replacing z ones: This option allo ws you t o remo ve a set of z ones and r eplac e them with a new set of z ones . •Impr oving a r egion: This option allo ws you t o define a c avity around sk ewed c ells in the e xisting mesh. You can mo dify the mesh as appr opriate and then r emesh the c avity. The f ollowing sec tions descr ibe the c avity remeshing options: 21.7.1. Tetrahedr al Cavity Remeshing 21.7.2. Hexcore Cavity Remeshing 21.7.1. Tetrahedr al C avity Remeshing The gener ic pr ocedur e for remeshing a c avity with t etrahedr a using the Cavity Remesh dialo g box is as follows: 1.Selec t the appr opriate zones fr om the Remo ve Boundar y Zones and Add B oundar y Zones selec tion lists . •Remo ving Z ones : Selec t the z ones t o be remo ved in the Remo ve Boundar y Zones selec tion list. Make sure tha t no z ones ha ve been selec ted in the Add B oundar y Zones list. •Adding Z ones : Selec t the z ones t o be added in the Add B oundar y Zones selec tion list. Make sur e tha t no z ones ha ve been selec ted in the Remo ve Boundar y Zones list. •Replacing Z ones : Selec t the z ones t o be remo ved in the Remo ve Boundar y Zones selec tion list and the z ones t o be added in the Add B oundar y Zones selec tion list. •Impr oving a Region : Make sur e tha t no z ones ha ve been selec ted in the Remo ve Boundar y Zones and Add B oundar y Zones selec tion lists . 2.Enable Create Face Group if you w ant to create a user-defined gr oup (UDG) c ompr ising the z ones defining the c avity domain. The cavity UDG and the c orresponding cavity domain will b e created, but the global domain will be retained as ac tive when the Create Face Group option is enabled .When this option is disabled , the cavity domain will b e ac tivated when the c avity is cr eated. Imp ortant The Create Face Group option is useful when using the c avity remeshing f eature for large c ases . For such c ases , you c an a void fr equen t swit ching b etween domains b y en- abling the Create Face Group option when cr eating the c avity.The basic pr ocedur e is as follows: a.Create a UDG f or the c avity and sa ve the b oundar y mesh f or the c avity gr oup defined using the File/W rite/Boundar ies... option (see Writing B oundar y Mesh F iles (p.106)). b.Read this b oundar y mesh in a separ ate session and cr eate the v olume mesh in the c avity as appr opriate. c.Save the v olume mesh and r ead it back in to the pr evious session using the Append F ile(s) option. 461Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Cavity Remeshingd.Connec t the meshed c avity to the par ent mesh and mer ge the c avity domain with the parent domain. 3.Enter an appr opriate value f or Scale and click Comput e.The e xtents of the b ounding b ox will b e comput ed (based on the z ones selec ted in the Remo ve Boundar y Zones and Add B oundar y Zones selec tion lists , and the sc ale fac tor sp ecified) and r eported in the Cavity Remesh dialo g box. Alternatively, you c an specify the e xtents of the b ounding b ox as r equir ed. Warning You need t o manually sp ecify the e xtents of the b ounding b ox when using the cavity remeshing f eature to impr ove a r egion of sk ewed c ells. 4.Specify the or ientation of the b ounding b ox in the Orient group b ox. 5.Click Draw to pr eview the c avity domain t o be created. 6.Click Create to create the c avity domain. The b oundar y zones t ouching the c avity bounding b ox will b e separ ated and included in the c avity domain along with the new z ones t o be added . Any zones t o be re- moved will not b e included in the c avity domain. The e xisting v olume mesh in the c avity will b e remo ved and b oundar y zones e xtracted fr om the in terior z ones (if an y) will b e changed t o internal type and included in the c avity domain. 7.Connec t the new z ones with the b oundar ies of the c avity domain using no de mer ging or in tersec t op er- ations when r emo ving , adding , or r eplacing z ones in the v olume mesh. Refer to Manipula ting B oundar y Nodes (p.273) and Intersec ting B oundar y Zones (p.274) for details . Modify the b oundar y mesh (if r equir ed) when impr oving a r egion in the v olume mesh. Refer to Manipula ting the B oundar y Mesh (p.273) for details on the v arious mesh impr ovemen t options . 8.Activate the c avity domain and cr eate the v olume mesh as appr opriate. Figur e 21.5: Cavity Around a M irror R emeshed With Tetrahedr a (p.463) sho ws a c avity created ar ound the r ear-view mir ror of a c ar.You c an see the or iginal mesh and the c avity created ar ound the mirror and r emeshed with t etrahedr a.The b ounding b ox defined f or the c avity is also sho wn. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 462Impr oving the M eshFigur e 21.5: Cavity Around a M irror Remeshed With Tetrahedr a 9.Activate the global domain and delet e the b oundar y zones which ar e no longer r equir ed. Merge the cavity domain with the par ent domain using the c ommand /mesh/cavity/merge-cavity . During the mer ging op eration, the c avity cell z ones will b e mer ged with the c ell z ones in the par ent domain. The b oundar ies e xtracted fr om the in terior z ones will b e converted t o interior type and mer ged with the c orresponding z ones in the par ent domain. Other b oundar y zones included in the c avity domain will b e mer ged with the par ent fac e zones . 21.7.2. Hexcore Cavity Remeshing The gener ic pr ocedur e for remeshing a c avity with a he xcore mesh using the Cavity Remesh dialo g box is as f ollows: 1.Selec t the appr opriate zones fr om the Remo ve Boundar y Zones and Add B oundar y Zones selec tion lists . •Remo ving Z ones : Selec t the z ones t o be remo ved in the Remo ve Boundar y Zones selec tion list. Make sure tha t no z ones ha ve been selec ted in the Add B oundar y Zones list. •Adding Z ones : Selec t the z ones t o be added in the Add B oundar y Zones selec tion list. Make sur e tha t no z ones ha ve been selec ted in the Remo ve Boundar y Zones list. •Replacing Z ones : Selec t the z ones t o be remo ved in the Remo ve Boundar y Zones selec tion list and the z ones t o be added in the Add B oundar y Zones selec tion list. •Impr oving a Region : Make sur e tha t no z ones ha ve been selec ted in the Remo ve Boundar y Zones and Add B oundar y Zones selec tion lists . Note •Hexcore cavity remeshing is not supp orted f or baffles/dangling w alls. •Hexcore cavity remeshing is not supp orted if the mesh c ontains an y dead c ell z ones . 463Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Cavity Remeshing2.Enable Hexcore Cavity to remesh the c avity with he xcore mesh. Note If this option is disabled , only the t etrahedr al cells in the c avity will b e replac ed dur ing the c avity remeshing . 3.Enter an appr opriate value f or Scale and click Comput e.The e xtents of the b ounding b ox will b e comput ed (based on the z ones selec ted in the Remo ve Boundar y Zones and Add B oundar y Zones selec tion lists , and the sc ale fac tor sp ecified) and r eported in the Cavity Remesh dialo g box. Alternatively, you c an specify the e xtents of the b ounding b ox as r equir ed. Warning You need t o manually sp ecify the e xtents of the b ounding b ox when using the cavity remeshing f eature to impr ove a r egion of sk ewed c ells. Note The Orient group b ox will b e disabled when the Hexcore Cavity option is enabled . 4.Click Draw to pr eview the c avity domain t o be created. Note Any dead c ells which in tersec t the c avity bounding b ox should b e converted t o fluid or solid t ype. 5.Click Create to create the c avity domain. The b oundar y zones t ouching the c avity bounding b ox will b e separ ated and included in the c avity domain along with the new z ones t o be added . Any zones t o be re- moved will b e delet ed fr om the global domain. The e xisting v olume mesh in the c avity will b e remo ved and b oundar y zones e xtracted fr om the in terior z ones (if an y) will b e changed t o internal type and included in the c avity domain. 6.Connec t the new z ones with the b oundar ies of the c avity domain using no de mer ging or in tersec t op er- ations when r emo ving , adding , or r eplacing z ones in the v olume mesh. Ensur e tha t the new b oundar ies are pr operly connec ted with the e xisting b oundar ies. Refer to Manipula ting B oundar y Nodes (p.273) and Intersec ting B oundar y Zones (p.274) for details . Modify the b oundar y mesh (if r equir ed) when impr oving a region in the v olume mesh. Refer to Manipula ting the B oundar y Mesh (p.273) for details on the v arious mesh impr ovemen t options . 7.If requir ed, create the pr ism la yers as appr opriate. Imp ortant To facilita te easier scr ipting of design changes in H excore meshes with pr ism la yers using the C avity Remeshing utilit y, the pr ism base b oundar y zones separ ated dur ing the c avity Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 464Impr oving the M eshcreation ar e suffix ed b y _cavity-pr ism:# .This allo ws you t o easily iden tify the z ones t o be assigned pr ism gr owth settings while r emeshing . 8.Click Remesh to create the v olume mesh in the c avity. During the r emeshing op eration, the c avity cell z ones will b e mer ged with the c ell z ones in the parent domain. The b oundar ies e xtracted fr om the in terior z ones will b e converted t o interior type and mer ged with the c orresponding z ones in the par ent domain. If the r emeshing in volves he xcore mesh gener ated t o selec ted b oundar ies, the old b oundar ies will b e remo ved and r eplac ed dur ing the r emeshing op eration. Note Do not change domains b etween the Create and Remesh operations . Figur e 21.6: Cavity Around a M irror R emeshed With H excore M esh (p.465) sho ws the pr ocedur e for creating a c avity to replac e the r ear-view mir ror of a c ar.You c an see the or iginal mesh and the c avity created ar ound the mir ror. Prisms ar e then gener ated and the c avity is r emeshed with he xcore mesh. Figur e 21.6: Cavity Around a M irror Remeshed With H excore M esh 465Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Cavity Remeshing21.8. Manipula ting C ell Z ones When a v olume mesh is cr eated (of an y cell shap e) fr om a b oundar y mesh, these c ells will b e gr oup ed into cell z ones (c ontiguous z ones separ ated b y boundar ies). You c an manipula te these z ones t o control further mesh gener ation or t o duplic ate an e xisting v olume mesh t o mo del a r epeated geometr y. 21.8.1. Active Zones and C ell Types 21.8.2. Copying and M oving C ell Z ones 21.8.1. Active Zones and C ell Types After the initial mesh is gener ated, all the c ells ar e gr oup ed in to contiguous z ones separ ated b y boundar ies. An ar tifac t of the meshing algor ithm is tha t a vir tual z one is cr eated outside the out er boundar y, and it is alw ays giv en a c ell t ype of dead .This z one is aut oma tically delet ed up on c ompletion of the initial mesh gener ation. If the initial mesh gener ation is in terrupted f or some r eason, this z one will r emain in the mesh un til the initializa tion is c omplet ed. Other z one t ypes a vailable ar e fluid and solid . The z one just inside the out er b oundar y is aut oma tically set t o be ac tive and lab eled a fluid z one , al- though y ou c an change this t ype later.When r efining the mesh, only the ac tive zones ar e refined . By toggling the z ones b etween ac tive and inac tive, you c an r efine diff erent groups of z ones indep enden tly, using diff erent mesh par amet ers f or the diff erent groups . If you plan t o refine all c ell z ones using the same r efinemen t par amet ers, change the Non-F luid Type in the Tet dialo g box before initializing the mesh. If you change the Non-F luid Type to an y type other than dead , all z ones will b e set ac tive aut oma tically af ter the initializa tion o ccurs .This elimina tes the need f or y ou t o set all z ones t o be ac tive in the Cell Z ones dialo g box. 21.8.2. Copying and M oving C ell Z ones If you ar e creating a mesh f or a geometr y tha t repeats p eriodically, you c an simplify the meshing tasks . To do this , create the b oundar y and v olume mesh f or just one of the r epeated sec tions . Copy the ap- propriate cell z ones t o the r equir ed lo cations . If the c opy shar es a b oundar y with the or iginal z one (tha t is, if the t wo zones ar e connec ted), ensur e tha t the distr ibution of no des is the same on the t wo overlaid b oundar ies. A simplified c ase is illustr ated in Figur e 21.7: Copying and Transla ting a C ell Z one (p.467). Here, the volume mesh w as cr eated f or z one 1, and then c opied and tr ansla ted t o cr eate zone 2. The no de dis- tribution on the lef t boundar y of z ones 1 and 2 is the same as the distr ibution on the r ight boundar y. Because the lef t boundar y of z one 2 is o verlaid on the r ight boundar y of z one 1, ther e will b e duplic ate nodes. It is imp ortant tha t you mer ge these duplic ate no des. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 466Impr oving the M eshFigur e 21.7: Copying and Transla ting a C ell Z one The pr ocedur e for doing this is as f ollows: 1.Open the Merge B oundar y Nodes dialo g box. 2.Compar e all no des on b oth b oundar ies.To do this , selec t the t wo zones in b oth the Compar e... and With... group b oxes. 3.Disable Only F ree N odes for b oth the z ones . 4.Click the Merge butt on t o mer ge the duplic ate no des. After the duplic ate no des on the t wo boundar ies ha ve been mer ged , one of the t wo boundar y fac e zones will b e delet ed aut oma tically. Because duplic ate fac es ar e mer ged when the duplic ate no des are mer ged , one z one will no longer ha ve an y fac es. 21.9. Manipula ting C ell Z one C onditions Case files r ead in the meshing mo de also c ontain the b oundar y and c ell z one c onditions along with the mesh inf ormation. The Cell Z one C onditions dialo g box enables y ou t o copy or clear c ell z one conditions when a c ase file is r ead. •You c an c opy the c ell z one c onditions fr om the z one selec ted in the With list t o those selec ted in the Without list using the Copy option. •You c an clear the c ell z one c onditions assigned t o the z ones selec ted in the With list using the Clear option. 467Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Manipula ting C ell Z one C onditions21.10. Using D omains t o Group and M esh B oundar y Faces Domains allo w you t o gr oup diff erent boundar y zones t ogether so tha t you c an cr eate tetrahedr al meshes in the r egion the y enclose , or y ou c an limit the z ones a vailable f or a displa y or r eport to only those z ones in a selec ted subset of the domain, rather than the en tire domain. 21.10.1. Using D omains 21.10.2. Defining D omains 21.10.1. Using D omains If you ar e gener ating a h ybrid mesh c ontaining he xahedr a, tetrahedr a, and p yramids , you c an iden tify a domain of the global mesh as the r egion in which y ou w ant to gener ate tetrahedr al cells.You c an also use domains t o gr oup b oundar y zones so tha t you c an p erform diagnostics on them or displa y them. When y ou displa y the gr id, the z ones a vailable f or displa y will b e only those z ones tha t are in- cluded in the ac tive domain. Similar ly, diagnostic r eports will r eport inf ormation ab out only those zones . •If you w ant to check a subset of the global domain, you c an cr eate and ac tivate a domain tha t includes the desir ed z ones , and then pr oceed with the displa y or r eport. •If you w ant your gr id displa y or r eport to include all z ones in the mesh, activate the global domain in the Domains dialo g box. 21.10.2. Defining D omains The pr ocedur e for defining a new domain is as f ollows: 1.Deselec t all z ones in the Boundar y Zones list and click Create. It is quick er to create an empt y domain and then add the z ones y ou w ant, inst ead of cr eating a domain with man y zones and then r emo ving those y ou do not w ant. 2.In the Boundar y Zones list, selec t the z ones y ou w ant to include in the new domain. If you ar e not sur e about the z ones , click Draw to displa y the z ones tha t are cur rently selec ted in the Boundar y Zones list. It is p ossible t o selec t all tr iangular or quadr ilateral b oundar y fac e zones b y cho osing tri or quad in the Boundar y Zone G roups list. •If you ar e creating a domain within a h ybrid mesh t o create tetrahedr a, mak e sur e tha t the domain contains all z ones r equir ed t o enclose the r egion tha t is t o be meshed with t etrahedr a, and only those zones . •If the z ones y ou selec t do not c omplet ely enclose the r egion, or if y ou include additional z ones tha t do not b ound this r egion, the t etrahedr al meshing is lik ely t o fail or b e inc orrect. 3.Click Change .The dialo g box will b e up dated so tha t the no de, face, and c ell z ones highligh ted in their respective lists ar e those tha t are affilia ted with the b oundar y zones in the domain. 4.Selec t the domain tha t you w ant to mesh (or displa y or r eport on) in the Domains list, and then click the Activate butt on.This domain is then c onsider ed t o be the ac tive domain, and the Activate butt on is disabled un til you selec t another domain. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 468Impr oving the M eshBy default , the most r ecently cr eated domain is aut oma tically set t o be the ac tive domain, so y ou only need t o explicitly set the ac tive domain if it is not the one y ou just cr eated. Note If you ar e dissa tisfied with the domain definition, delet e it using the Delet e butt on and start over, or mo dify it b y selec ting it and using the Change butt on. 21.11. Check ing the M esh When y ou c omplet e the mesh gener ation pr ocess, you need t o check the mesh b efore sa ving it. The mesh check ing c apabilit y will check the mesh c onnec tivit y and the or ientation of the fac es (fac e handedness , which should b e right-handed f or all fac es b ecause the solv ers use a r ight-handed sy stem). The domain e xtents and sta tistics f or v olume and fac e ar ea will b e reported along with the r esults of other checks on the mesh. Mesh → Check . The mesh check inf ormation will b e pr inted in the c onsole .The sample output is as f ollows: Domain extents. x-coordinate: min = -2.500000e+00, max = 2.500000e+00. y-coordinate: min = -4.357625e-15, max = 2.000000e+00. z-coordinate: min = -1.111022e-04, max = 2.000000e+00. Volume statistics. minimum volume: 2.297312e-09. maximum volume: 7.856795e-03. total volume: 1.953600e+01. Face area statistics. minimum face area: 1.258676e-06. maximum face area: 4.944555e-02. average face area: 1.939640e-04. Checking number of nodes per edge. Checking number of nodes per face. Checking number of nodes per cell. Checking number of faces/neighbors per cell. Checking cell faces/neighbors. Checking isolated cells. Checking face handedness. Checking periodic face pairs. Checking face children. Checking face zone boundary conditions. Checking for invalid node coordinates. Checking poly cells. Done. The domain e xtents list the x, y, and z c oordina tes in met ers. The v olume sta tistics include the maximum, minimum, and t otal c ell v olume in m3. A nega tive value for the minimum v olume indic ates tha t one or mor e cells ha ve impr oper connec tivit y.The nega tive volume c ells should b e elimina ted b efore the c omputing the flo w solution. The fac e ar ea sta tistics include the maximum, minimum, and a verage fac e ar ea in m2. A v alue of z ero for minimum fac e ar ea indic ates tha t one or mor e cells ha ve degener ate fac es.The mesh check ma y also fail if c ells ha ve fac es with v ery small non-z ero fac e ar eas. Such c ells should also b e corrected b efore computing the flo w solution. 469Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Check ing the M eshThe t opological inf ormation v erified includes the numb er of no des and fac es p er cell. A tetrahedr al cell should ha ve 4 fac es and 4 no des while a he xahedr al cell should ha ve 6 fac es and 8 no des. Next, the fac e-handedness and fac e no de or der f or each z one will b e check ed.The z ones should c ontain all r ight-handed fac es and all fac es should ha ve the c orrect no de or der. Besides this , the mesh check report will also displa y warnings based on the r esults of the checks pr eviously descr ibed. If an y pr oblems are reported, you need t o repair the mesh. Note The mesh check will issue a w arning if multiple c ell z ones ar e main tained acr oss an interior boundar y.The b oundar y type in such c ases should b e set t o internal inst ead. 21.12. Selec tively C heck ing the Volume M esh After cr eating a v olume mesh, it is imp ortant to perform a thor ough check of the mesh in or der t o ensur e that the mesh is v alid. In some c ases , you migh t prefer to ha ve mor e control o ver wha t asp ects of the mesh ar e check ed, or y ou ma y wish t o perform the mesh check on sp ecific z ones , rather than all z ones . To selec tively check the v olume mesh, use the c orresponding option a vailable under the Mesh menu . Mesh → Selec tive Check This displa ys the Selec tive M esh C heck dialo g wher e you c an ha ve mor e fle xibilit y and mor e gr anular control o ver the mesh check pr ocedur e and sc ope. Figur e 21.8: The S elec tive M esh C heck D ialo g 1.Selec t one or mor e cell z ones fr om the Cell Z one list. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 470Impr oving the M esh2.Alternatively, you c an selec t one or mor e gr oups of c ell z ones fr om the Cell Z one G roups list. 3.From the Paramet ers group , selec t specific it ems fr om the list of a vailable mesh check ing c ategor ies, use the Selec t All or Deselec t All butt ons acc ordingly , or k eep the default selec tion of all the it ems . •Domain E xtents •Volume S tatistics •Face Area S tatistics •Numb er of N odes p er E dge •Numb er of N odes p er F ace •Numb er of N odes p er C ell •Numb er of F aces/N eighb ors p er C ell •Cell F aces/N eighb ors •Isola ted C ells •Face Handedness •Periodic F ace Pairs •Face Childr en •Zone B oundar y Conditions •Invalid N ode C oordina tes •Poly C ells 4.Onc e the c ell z one(s) and the par amet ers ar e selec ted, click the Check butt on t o perform the selec tive mesh check, and view the output in the c onsole windo w.The check is p erformed f or the selec ted z one and the c orresponding adjac ent fac es, including the in teriors of the selec ted z one , as w ell as an y corres- ponding edges . You c an p erform a selec tive mesh check using the t ext user in terface (TUI). mesh/selective-mesh-check The c ommand will pr ompt y ou f or one or mor e cell z ones , as w ell as whether t o include an y of the mesh check par amet ers. For e xample: Meshing/mesh> selective-mesh-check Select one or more cell zones for the mesh check. Available cell zone(s): (solid_up:232 fluid1) () Cell Zones(1) [()] fluid1 Cell Zones(2) [()] Specify selective mesh check parameters: Domain Extents? [yes] y Volume Statistics? [yes] y Face Area Statistics? [no] n Number of Nodes per Edge? [no] n Number of Nodes per Face? [yes] n Number of Nodes per Cell? [yes] n 471Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Selec tively C heck ing the Volume M eshNumber of Faces/Neighbors per Cell? [no] n Cell Faces/Neighbors? [no] n Isolated Cells? [yes] n Face Handedness? [yes] n Periodic Face Pairs? [yes] n Face Children? [yes] n Zone Boundary Conditions? [yes] n Invalid Node Coordinates? [yes] n Poly Cells? [yes] n Onc e the pr ompts ar e complet e, the mesh check will pr oceed and displa y the r esults in the c onsole windo w. For e xample , given the pr evious input e xample , the output w ould lo ok lik e: Mesh check for cell zone(s): (fluid1) Domain extents. x-coordinate: min = -3.627150e+02, max = 1.345894e+01. y-coordinate: min = -1.250188e+02, max = 2.475194e-09. z-coordinate: min = -1.018144e+02, max = 1.343869e+01. Volume statistics. minimum volume: 1.420005e-03. maximum volume: 2.548519e+02. total volume: 8.211535e+05. Done. 21.13. Check ing the M esh Q ualit y It is imp ortant to check the qualit y of the v olume mesh t o evalua te whether it is sufficien t for the problem y ou ar e mo deling . It is r ecommended tha t you check the mesh qualit y before transf erring the mesh da ta to solution mo de or wr iting out the mesh/c ase file . You c an obtain inf ormation ab out the v olume mesh qualit y by selec ting the Mesh/C heck Q ualit y menu item. Mesh → Check Q ualit y When y ou selec t Mesh → Check Q ualit y, the qualit y inf ormation will b e pr inted in the c onsole .The sample output is as f ollows: Mesh Quality: Minimum Orthogonal Quality = 6.07960e-01 (To improve Orthogonal quality, use "Inverse Orthogonal Quality", where Inverse Orthogonal Quality = 1 - Orthogonal Quality) Maximum Aspect Ratio = 5.42664e+00 Note The qualit y reported c orresponds t o tha t reported using the Rep ort Qualit y butt on in the Gener al task page in solution mo de (r efer to Mesh Q ualit y (p.719) for details). For inf ormation ab out additional qualit y metr ics, set the /mesh/check-quality-level to 1 prior to using the Mesh → Check Q ualit y option. In addition t o the or thogonal qualit y and F luen t asp ect ratio, additional metr ics such as c ell squish and sk ewness will b e reported when the check-quality- level is set t o 1. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 472Impr oving the M esh21.14. Clear ing the M esh If you ar e dissa tisfied with the v olume mesh gener ated, you c an cho ose t o clear the mesh and star t again fr om the b oundar y mesh. When the mesh is clear ed, all in terior no des and fac es, and all c ells both liv e and dead ar e delet ed. Only the b oundar y no des and fac es will b e lef t. After the mesh is clear ed, you c an gener ate a new mesh. This f eature is a vailable via Mesh → Clear . You c an also use the t ext command /mesh/clear-mesh .To delet e the b oundar y mesh, use the t ext command mesh/reset-mesh .When y ou use either of these c ommands y ou will b e ask ed t o confir m that you w ant to clear or r eset the mesh. Imp ortant If you ha ve used domains t o gener ate the mesh or gr oup ed z ones f or reporting (as descr ibed in Using D omains t o Group and M esh B oundar y Faces (p.468)), only the mesh in the ac tive domain will b e clear ed. 473Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Clearing the M eshRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 474Chapt er 22: Examining the M esh The f ollowing sec tions e xplain ho w to examine the mesh visually as w ell as manipula te the gr aphics displa y and mouse func tion. You c an sp ecify v arious par amet ers tha t aff ect ho w the mesh app ears in the gr aphics windo w, manipula te the ligh ting and cr eate comp osite view s, control the displa y en viron- men t, mo dify the mouse butt on func tions , and set pr ogram c ontrol variables . 22.1. Displa ying the M esh 22.2. Controlling D ispla y Options 22.3. Modifying and S aving the View 22.4. Comp osing a Sc ene 22.5. Controlling the M ouse B uttons 22.6. Controlling the M ouse P robe Function 22.7. Annota ting the D ispla y 22.8. Setting D efault C ontrols 22.1. Displa ying the M esh You c an manipula te the displa y of mesh en tities and mo dify the w ay the y app ear in the gr aphics windo w. Options e xist f or dr awing and selec ting the en tities a t your choic e of c omple xity (objec t, zone , face, edge , node). Tools e xist f or setting c olors or highligh ting based on sp ecific par amet ers such as fr ee or multiply-c onnec ted, size field , or geometr y recovery.You c an also manipula te the displa y to sho w a cross-sec tion, adjust ligh ting , or o verlay multiple images . 22.1.1. Gener ating the M esh D ispla y using Onscr een Tools 22.1.2. Gener ating the M esh D ispla y Using the D ispla y Grid D ialog Box 22.1.1. Gener ating the M esh D ispla y using Onscr een Tools The most c ommonly used mesh displa y tools ar e easily acc essible in the gr aphic al user in terface ribbon. For mor e fle xibilit y and ad vanced displa y controls, see Gener ating the M esh D ispla y Using the D ispla y Grid D ialog Box (p.476). In the M odel tr ee, selec t the objec ts to be displa yed using the r ight mouse butt on. At the global Geometr y O bjec ts or Mesh O bjec ts level, you c an cho ose t o Draw A ll. At the individual objec t level, the Draw menu it em allo ws you t o dr aw the selec ted objec t exclusiv ely, or use the Draw Options menu t o Add to or Remo ve from the e xisting displa y, as w ell as Highligh t or Selec t the objec t. In the meshing mo de r ibbon, ther e ar e gr oups of t ools t o in teractively cr op the displa y of the mesh, to assist in selec ting z ones or objec ts, or t o mo dify ho w the mo del is displa yed in the gr aphics windo w. •You c an use the Bounds group t o limit the displa y to within a sp ecified distanc e of a selec ted en tity. Selec t an en tity (no de, edge , face, zone) and sp ecify a Delta value .The Set R anges and Reset butt ons aff ect all dir ections simultaneously , or enable and disable the dir ections individually . 475Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Enable Cutplanes to limit the gr aphics displa y to within delta v alue of the selec ted en tity in the selec ted r anges . Tip The settings in the Bounds group ar e also a vailable when e xamining the v olume mesh. The Displa y → Grid dialo g box has a Bounded check b ox on the Cells tab , and the Cell Z ones context menu includes an option t o displa y the c ells in the specified r ange . •You c an use the Clipping P lanes group t o interactively cr op the displa y in one dir ection and pan the cropp ed view as nec essar y. Enable Inser t Clipping P lanes and use the slider t o adjust the viewing limits .You c an use the Flip and Limit in options t o fur ther manipula te the p osition and dir ection of the clipping plane . You c an also use the Show C ut E dges option t o displa y the cut edges of the mo del e xposed by the clipping plane .This option is disabled b y default. Enable the Draw C ell L ayer option in or der t o quick ly visualiz e a la yer of c ells of the v olume mesh on the clipping plane . Onc e the Draw C ell L ayer option is enabled , you c an enable the Freeze Cell L ayer option in or der t o keep the displa yed c ell la yer in plac e as y ou c ontinue t o stud y the mesh using other t ools. To dr aw a la yer of c ells on the clipping plane f or sp ecific c ell z ones , selec t the c ell z one(s) under Mesh O bjec ts in the Tree and use the Draw C ell L ayer option in the c ontext menu . •You c an use the Selec tion H elper group t o assist in selec ting z ones or objec ts by a Name P attern (wild c ards acc epted) and Geometr y Rec overy level. Use the Filter drop do wn t o sp ecify fac e zones , edge z ones , objec ts, objec t fac e zones or objec t edge z ones f or selec tion. The Advanc ed butt on op ens a dialo g box off ering mor e options f or zone selec tion. •You c an use the Selec tion group t o cho ose ho w to selec t en tities using the mouse in the gr aphics displa y. •The Global D ispla y group c ontains se veral check b oxes to enable or disable c ertain elemen ts of the graphics windo w (Title, Help Text) or mo del displa y (Faces, Edges , Highligh ts). •The Local D ispla y group c ontains se veral tools t o help with visualizing the cur rent mo del. These include Transpar ency, Explo ded view , Centroid, Edge Z one selec tion mo de, Face edge displa y and M easur e Distanc e. •Several on-scr een t ool butt ons ha ve asso ciated hot-k eys. A complet e list is a vailable in Shortcut Ke y Actions (p.527). 22.1.2. Gener ating the M esh D ispla y Using the D ispla y Grid D ialo g Box The Displa y Grid dialo g box includes a full set of t ools t o control the displa y of it ems using se veral criteria. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 476Examining the M eshTo gener ate the mesh displa y: 1. Selec t Displa y → Grid.... 2. Selec t the en tities t o be displa yed in the Zones lists in the Nodes,Edges ,Faces, or Cells tabs .You c an also selec t several en tities of the same gr oup using the Zone G roups lists in these tabs . 3. Selec t the displa y Options as appr opriate from the gr oup b ox in the Nodes,Edges ,Faces, or Cells tabs . You ma y selec t intrinsic par amet ers such as sk ewness or siz e.When y ou sp ecify a r ange f or a particular par amet er, the en tities tha t satisfy tha t condition ar e displa yed. If mor e than one r ange limita tion is sp ecified , then only those en tities tha t ma tch all sp ecified r ange limita tions ar e dr awn. 4. The Bounds tab off ers enhanc ed func tionalit y relative to the r ibbon gr oup . You ma y inser t up t o six cutplanes (t wo in each of the x-, y-, and z-dir ection) and asymmetr ically control their lo cation based on sp ecific c oordina tes. Alternatively, you c an c omput e ranges based on the pr oximit y to a selec ted en tity. 5. Set the displa y options as appr opriate in the Attribut es tab . See Mesh D ispla y Attribut es (p.477) You c an sp ecify inf ormation r egar ding c olor , displa y of solid (filled) fac es, and shr inkage of fac es and c ells.These f eatures c an help y ou visualiz e your mesh eff ectively and quick ly det ermine the cause of an y pr oblems in the mesh. 6. Click Displa y to dr aw the mesh in the ac tive gr aphics windo w. To cancel a displa y op eration, press Ctrl+C while the da ta is b eing pr ocessed in pr epar ation f or graphic al displa y.You c annot c ancel the op eration af ter the pr ogram b egins t o dr aw in the graphics windo w. 22.1.2.1. Mesh D ispla y Attribut es The mesh displa y options include mo difying the mesh c olors , adding the outline of imp ortant features to a displa y, displa ying nor mals , shr inking the fac es and/or c ells in the displa y, adding ligh ts for filled mesh displa ys, and so on. Mo difying the Mesh C olors You c an c ontrol the c olors used t o render the mesh f or each z one t ype or en tity.You c an mo dify the colors using the Grid C olors dialo g box. 1. To op en the Grid C olors dialo g box, go t o the Attribut es tab in the Displa y Grid dialo g box, and click Colors .... By default , the Color b y Type option is selec ted, enabling y ou t o assign c olors based on z one type. 2. To change the c olor assigned t o a par ticular z one t ype, selec t the z one t ype in the Types list. 3. Selec t the r equir ed c olor in the Colors list. 4. If you pr efer to assign c olors based on the z one ID , selec t the Color b y ID option. 477Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Displa ying the M esh5. Selec t Color b y Normal to color one side of the fac es in gr ey and the other side in y ellow, dep ending on the nor mal dir ection. The side c olor ed gr ey indic ates nor mal dir ection (nor mals p ointing t oward you), while the side c olor ed y ellow has nor mals p ointing a way. Imp ortant You c an set c olors individually f or the mesh displa yed on each of the z ones using the Scene D escr iption dialo g box. Adding F eatur es t o an O utline D ispla y For closed 3D geometr ies, the standar d outline displa y ma y not sho w sufficien t details t o accur ately depic t the shap e.This is b ecause f or each b oundar y, only the edges on the outside of the geometr y (tha t is, those used b y only one fac e on the b oundar y) ar e dr awn. You c an c aptur e additional f eatures using the Feature option in the Displa y Grid dialo g box. Specify an appr opriate value f or the Feature Angle to obtain the outline displa y requir ed. Shrink ing F aces and C ells in the D ispla y To distinguish individual fac es or c ells in the displa y, you ma y want to enlar ge the spac e between adjac ent fac es or c ells b y incr easing the Shrink F actor in the Displa y Grid dialo g box.The default value of z ero pr oduces a displa y in which the adjac ent fac es or c ells o verlap. A v alue of 1 cr eates the opp osite extreme , wher e each fac e or c ell is r epresen ted b y a p oint and ther e is a c onsider able spac e between en tities . A small v alue such as 0.01 ma y be sufficien t to enable y ou t o distinguish a fac e or cell fr om its neighb or.Figur e 22.1: Mesh D ispla y (A) With S hrink F actor = 0 (B) With S hrink F actor = 0.01 (p.478) sho ws displa ys with diff erent Shrink F actor values . Figur e 22.1: Mesh D ispla y (A) With S hrink F actor = 0 (B) With S hrink F actor = 0.01 Adding Lights You c an add ligh ts with a sp ecified c olor and dir ection t o your displa y.These ligh ts can enhanc e the app earance of the displa y, esp ecially f or 3D geometr ies. •To enable the eff ect of ligh ting using the Displa y Options dialo g box, enable Ligh ts On in the Ligh ting Attribut es group b ox and click Apply .You c an also cho ose the metho d to be used in ligh ting in terpolation. Selec t Flat,Gour aud , or Phong in the Ligh ting drop-do wn list. Flat is the most basic metho d: ther e is no in terpolation within the individual p olygonal fac ets.Gour aud and Phong have smo other gr adations of color b ecause the y interpolate on each fac et. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 478Examining the M esh•The Ligh ts dialo g box contains options f or cr eating ligh ts and then enabling/disabling individual ligh ts as needed . In this w ay, you c an r etain ligh ts tha t you ha ve defined pr eviously but do not w ant to use a t presen t. The default ligh t,ligh t 0 is defined t o be dar k gr ay with a dir ection of (1,1,1). To define additional ligh ts, do the f ollowing: 1. Increase Ligh t ID to a new v alue (f or e xample , 1). 2. Enable Ligh t On . 3. Define the ligh t color b y en tering a descr iptiv e str ing (f or e xample ,lavender ) in the Color field , or by mo ving the Red ,Green , and Blue sliders t o obtain the desir ed c olor .The default c olor f or all ligh ts is dar k gr ay. 4. Specify the ligh t dir ection b y doing one of the f ollowing: –Enter the (X, Y, Z) C artesian c omp onen ts under Direction . –Click the middle mouse butt on in the desir ed lo cation on the spher e under Active Ligh ts. (You can also mo ve the ligh t along the cir cles on the sur face of the spher e by dr agging the mouse while holding do wn the middle butt on.) You c an r otate the spher e by pr essing the lef t mouse butt on and mo ving the mouse (lik e a tr ackball). –Use y our mouse t o change the view in the gr aphics windo w so tha t your p osition in r eference to the geometr y is the p osition fr om which y ou w ould lik e a ligh t to shine .Then click Use View Vector to up date the X,Y ,Z fields with the appr opriate values f or y our cur rent position and up date the graphics displa y with the new ligh t dir ection. This metho d is c onvenien t if y ou k now wher e you want a ligh t to be, but y ou ar e not sur e of the e xact dir ection v ector. 5. Repeat steps 1–4 t o add mor e ligh ts. 6. When the ligh ts ha ve been defined , click Apply in the Ligh ts dialo g box to sa ve the definitions . To remo ve a ligh t, enter the ID numb er of the ligh t to be remo ved in the Ligh t ID field and then clear the Ligh t On check b ox.When a ligh t is disabled , its definition is r etained , so y ou c an easily add it t o the displa y again a t a la ter time b y selec ting the Ligh t On check b ox. If you ha ve made changes t o the ligh t definitions , but y ou ha ve not y et click ed Apply , you c an reset the ligh ts b y click ing Reset . All ligh ting char acteristics will r evert to the last sa ved sta te (tha t is, the ligh ting tha t was in eff ect the last time y ou op ened the dialo g box or click ed on Apply ). Using St yles The Style A ttribut es dialo g box is op ened b y click ing on the Styles ... butt on in the Attribut es tab frame of the Displa y Grid dialo g box. It controls the app earance of fac es, edges , and no des tha t are displa yed using the Displa y Grid dialo g box.To mo dify the a ttribut es of a c ertain t ype of fac e, edge , 479Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Displa ying the M eshor no de (e .g., unmeshed), selec t the appr opriate item in the Styles list, change the par amet ers, and click Apply .You will see the eff ect of these changes the ne xt time y ou displa y the gr id. Table 22.1: Default S tyle A ttribut es Size Symb ol Color Visible Weigh t ColorNodes VisibleEdges ColorFaces VisibleStyles 0.5 o red yes 2 red yes red yes left-handed 0.5 o magen ta yes 2 yellow yes magen ta yes refine 0.5 o orange yes 2 foreground yes cyan yes free 0.5 o magen ta yes 2 foreground yes yellow yes multi 0.5 o red yes 2 orange yes – no unmeshed 0.5 x green yes 2 green yes – no unused 0.5 o magen ta yes 2 yellow yes magen ta yes mar k 0.5 o magen ta yes 2 yellow yes magen ta yes tag – – – no 1 foreground yes blue yes face-siz e – – – no 1 red yes – no cell-siz e – – – no 1 foreground yes red yes face-qualit y – – – no 1 red yes – no cell-qualit y 22.2. Controlling D ispla y Options The Displa y Options dialo g box contains options f or changing some of the r ender ing par amet ers f or the mesh displa yed in the gr aphics windo w.You c an also c ontrol the ligh ting a ttribut es in a sc ene or modify par amet ers based on the gr aphics har dware and sof tware you ar e using or change the gr aphics windo w la yout or c olor scheme . After mak ing a change t o an y of the par amet ers, click Apply to up date the ac tive gr aphics windo w with the new a ttribut es. Displa y → Options ... Render ing The f ollowing Render ing options ar e available: Line Width Use this c ontrol to incr ease the width fr om the default v alue of 1 pix el. Point Symb ol The default symb ol is a + sign inside a cir cle. Selec ting a diff erent symb ol in the Point Symb ol drop-do wn list ma y help visibilit y in some situa tions . Anima tion Options There are two anima tion options tha t you c an cho ose fr om: All uses a solid-t one shading r epresen tation of all geometr y dur ing mouse manipula tion. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 480Examining the M eshWireframe uses a wir eframe r epresen tation of all geometr y dur ing mouse manipula tion. If your c omput er has a graphics acc elerator, you ma y not w ant to use this option; other wise , the mouse manipula tion ma y be very slo w. Double Buff ering Enabling the Double Buff ering option c an dr ama tically r educ e scr een flick er dur ing gr aphics up dates. Note, however, tha t if y our displa y har dware do es not supp ort double buff ering and y ou tur n this option on, double buff ering will b e done in sof tware. Software double buff ering uses e xtra memor y. Out er F ace Culling This option enables y ou t o tur n off the displa y of out ward pointing fac es of shells or meshes .This is sometimes useful f or displa ying b oth sides of a slit w all. By default , when y ou displa y a slit w all, one side will “bleed ” through t o the other .When y ou enable the Out er F ace Culling option, the displa y of a slit wall will sho w each side distinc tly as y ou r otate the displa y.This option c an also b e useful f or displa ying two-sided w alls (tha t is, walls with fluid or solid c ells on b oth sides). Please not e, however, tha t enabling it can also hides some unin tended sur faces on c ertain viewing angles , e.g. while displa ying C ontours , it migh t be visible only fr om one side of the sur face and not fr om the other Hidden S urface Remo val If you use hidden sur face remo val, ANSY S Fluen t will tr y to det ermine which sur faces in the displa y are behind others . If you do not use hidden sur face remo val, all sur faces will b e displa yed, and a clutt ered displa y will r esult f or most 3D mesh displa ys. You c an cho ose one of the f ollowing metho ds for p erforming hidden sur face remo val in the Hidden Surface M etho d drop-do wn list. These options v ary in sp eed and qualit y, dep ending on the de vice you ar e using . Hardware Z-buff er is the fast est metho d if supp orted b y your har dware.The accur acy and sp eed of this metho d is har dware dep enden t. Painters will sho w fewer edge-aliasing eff ects than har dware-z-buff er.This metho d is of ten used inst ead of software-z-buff er when memor y is limit ed. Software Z-buff er is the fast est of the accur ate sof tware metho ds a vailable (esp ecially f or comple x scenes), but it is memor y intensiv e. Z-sor t only is a fast sof tware metho d, but it is not as accur ate as sof tware-z-buff er. Color Scheme Choose the back ground c olor — gr adien t (Workbench) or solid black (C lassic). Layout Choose t o enable or disable additional displa y sta tus inf ormation: 481Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Controlling D ispla y Options•Titles : caption blo ck ar ea b elow the gr aphic c ontaining da te, produc t, and c ontents of the displa y.The caption blo ck supp orts limit ed t ext editing . Position the cursor a t the end of a line t o add or delet e text. Text in the c aption blo ck will not b e delet ed when y ou clear Annota tions . •Axes: X-Y-Z tr iad sho wing or ientation. Click on the tip of one axis t o rotate the mo del t o the selec ted or tho- gonal view , or the c yan-c olor ed dot f or isometr ic view . •Scale R uler :Visual indic ator sho wing the siz e in the plane of the gr aphics displa y.The indic ator aut oma tically resizes as the mo del is z oomed in the gr aphics displa y. •Logo: ANSY S and v ersion numb er. •Color map : when displa ying simula tion r esults , the sc ale ma y be sho wn as func tion of the visible sp ectrum. Graphics D evice Inf ormation If you need t o know which gr aphics dr iver y ou ar e using and wha t graphics har dware it r ecogniz es, you c an click Info in the Displa y Options dialo g box.The gr aphics de vice inf ormation will b e pr inted in the t ext windo w. Note When w orking r emot ely, you c an optimiz e the gr aphics windo w settings using the t ext command remote-display-defaults . Restore the settings f or y our lo cal displa y using the t ext command native-display-defaults . 22.3. Modifying and S aving the View You c an use the Views dialo g box to control the mo del or ientation and z oom le vel in the gr aphics windo w. Displa y → Views •You c an cho ose isometr ic or one of the standar d or thographic view s from the list. The displa yed mo del will b e centered and z oomed t o fit the a vailable gr aphics windo w. You c an also use the Set vie w shor tcut ( ) in the View Tools (p.92) to set one of the standar d view s. •You c an mo dify the view b y scaling , centering, or r otating the mo del. You c an Save a mo dified view or Delet e any view fr om the list. •You c an use Write... to op en the Write Views dialo g box to sa ve selec ted view s to a file , which y ou can Read ... and use with other mesh files . 22.3.1. Mirroring a N on-symmetr ic D omain You c an use the Mirror P lanes dialo g box to define a symmetr y plane f or a non-symmetr ic domain for use with gr aphics . Click Define P lane ... to op en the dialo g box. 1. In the Plane E qua tion group b ox, specify the c oefficien ts of A, B, C, and the distanc e from the or igin. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 482Examining the M eshThe equa tion f or the mir ror plane will b e Ax+B y+C z=distanc e. 2. Click Add. The Mirror P lanes list c ontains a list of all mir ror planes y ou ha ve defined (but not the mir ror planes tha t exist in the domain due t o symmetr y as the y cannot b e mo dified). 3. Selec t a mir ror plane fr om the list. Click Apply to see b oth the or iginal and the mir rored image in the graphics windo w. 22.3.2. Controlling P ersp ective and C amer a Paramet ers You c an use the Camer a Paramet ers dialo g box to control p ersp ective and mo dify the “camer a” through which y ou ar e viewing the gr aphics displa y inst ead of tr ansla ting , rotating , and z ooming the displa y. You c an cho ose t o displa y a p ersp ective view of the gr aphics (default) or an or thographic view . Selec t the appr opriate option in the Projec tion drop-do wn list in the Camer a Paramet ers dialo g box.. The Camer a is defined b y four par amet ers (see Figur e 22.2: Camer a Definition (p.483)): Figur e 22.2: Camer a D efinition •Position is the c amer a’s location. •Target is the lo cation of the p oint the c amer a is lo oking a t. •Up Vector indic ates to the c amer a which w ay is up . •Field indic ates the field of view (width and heigh t) of the displa y. 483Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modifying and S aving the ViewSelec t the par amet er to be mo dified and sp ecify the c oordina tes or field distanc es in the X,Y, and Z fields . Click Apply after y ou change each c amer a par amet er. Imp ortant When using the sliders and dial t o manipula te the view , selec t All in the Displa y Options dialo g box so tha t you c an w atch the displa y mo ve in teractively while y ou mo ve the slider or the dial indic ator. 22.4. Comp osing a Sc ene After displa ying the mesh or par ts of the mesh in y our gr aphics windo w, you ma y want to overlay an additional displa y or mo ve en tities ar ound and change their char acteristics t o incr ease the eff ectiveness of the sc ene displa yed. Displa y → Scene ... You c an use the Scene D escr iption dialo g box—and the Displa y Properties dialo g box and the Transf ormations dialo g box tha t are op ened fr om it—t o rotate, transla te, and sc ale each en tity indi- vidually , as w ell as t o change the c olor and visibilit y of each en tity.You c an mak e geometr ic en tities visible and in visible , ther eby adding or deleting en tities fr om the sc ene one a t a time . 22.4.1. Changing the D ispla y Properties 22.4.2. Transf orming G eometr ic En tities in a Sc ene 22.4.3. Adding a B ounding F rame 22.4.4. Using the Sc ene D escr iption D ialog Box 22.4.1. Changing the D ispla y Properties To enhanc e the sc ene in the gr aphics windo w, you c an change the c olor , visibilit y, and other displa y properties of each geometr ic en tity in the sc ene using the options a vailable in the Displa y Properties dialo g box. •You c an sp ecify diff erent colors f or displa ying the edges and fac es of a z one t o sho w the under lying mesh (edges) when the fac es ar e filled and shaded . •You c an also mak e a selec ted en tity temp orarily in visible . If, for e xample , you ar e displa ying the en tire mesh for a c omplic ated pr oblem, you c an mak e en tities visible or in visible t o displa y only c ertain b oundar y zones of the gr id without r egener ating the gr id displa y using the Displa y Grid dialo g box. •You c an also use the visibilit y controls t o manipula te geometr ic en tities f or efficien t graphics displa y. For details , refer to Using the Sc ene D escr iption D ialog Box (p.485). 22.4.2. Transf orming G eometr ic Entities in a Sc ene When c omp osing a sc ene in y our gr aphics windo w, it is helpful t o mo ve a par ticular en tity from its original p osition or t o incr ease or decr ease its siz e. For e xample , you ma y want to temp orarily mo ve an in terior p ortion of the mesh outside the mesh b oundar ies wher e it c an b e seen and in terpreted mor e easily . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 484Examining the M eshYou c an also mo ve an en tity by rotating it ab out a sp ecified p oint. If you w ant to displa y one en tity mor e pr ominen tly than the others , you c an sc ale its siz e. All these c apabilities ar e available in the Transf ormations dialo g box. 22.4.3. Adding a B ounding F rame You c an optionally add a b ounding fr ame t o the displa y of the domain and include measur e mar kings to indic ate the length, heigh t, and/or width of the domain using the Bounding F rame dialo g box. Figur e 22.3: Graphics D ispla y with B ounding F rame To add a b ounding fr ame t o the displa y: 1. Click Frame Options ... in the Scene D escr iption dialo g box. 2. Selec t Domain or Displa y in the Frame E xtents list t o indic ate whether the b ounding fr ame should encompass the domain e xtents or only the p ortion of the domain tha t is sho wn in the displa y. 3. Indic ate the b ounding plane(s) t o be displa yed b y click ing on the whit e squar e on the appr opriate plane of the b ox sho wn under the Axes heading .You c an use an y of the mouse butt ons.The squar e will tur n red t o indic ate tha t the asso ciated b ounding plane will b e displa yed in the gr aphics windo w. 4. Specify wher e you w ould lik e to see the measur emen t annota tions b y click ing on the appr opriate edge of the b ox.The edge will tur n red t o indic ate tha t the mar kings will b e displa yed along tha t edge of the displa yed geometr y 5. Click Displa y to up date the displa y with the cur rent settings . If you w ant to include the b ounding fr ame in all subsequen t displa ys, enable the Draw F rame option in the Scene D escr iption D ialo g Box and click Apply . If this option is not enabled , the b ounding b ox will app ear only in the cur rent displa y; it will not b e redispla yed when y ou gener ate a new displa y (unless y ou ha ve overlays enabled). 22.4.4. Using the Sc ene D escr iption D ialo g Box You c an use the Scene D escr iption dialo g box and its asso ciated dialo g boxes as f ollows: 1. Selec t the mesh en tities in the Names selec tion list in the Scene D escr iption dialo g box. 485Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Comp osing a Sc eneThe Names list is a list of the mesh en tities tha t cur rently e xist in the sc ene (including those tha t are pr esen tly in visible). If you selec t mor e than one en tity, any op eration (c olor sp ecific ation, transf ormation, and so on) will apply t o all the selec ted en tities .You c an also selec t the en tities by click ing them in the gr aphics windo w using the mouse pr obe butt on (r ight mouse butt on, by default). 2. Set the c olor , visibilit y, and other displa y pr operties f or the mesh en tities selec ted using the Displa y Properties dialo g box. •You c an sp ecify diff erent colors f or individual mesh en tities .You c an sp ecify diff erent colors f or dis- playing the edges and fac es of a z one t o sho w the under lying mesh (edges) when the fac es of the grid ar e filled and shaded . To mo dify the c olor of fac es, edges , or lines , cho ose face-color ,edge-c olor ,line-c olor , or node- color in the Color drop-do wn list. The Red ,Green , and Blue color sc ales will sho w the R GB comp onen ts of the fac e, edge or line c olor , which y ou c an mo dify b y mo ving the sliders on the color sc ales .When y ou ar e sa tisfied with the c olor sp ecific ation, click Apply to sa ve it and up date the displa y. •You c an c ontrol the visibilit y of individual mesh en tities using the Visible option. Hence, you c an mak e an en tity visible or in visible t o displa y only c ertain b oundar y zones , without r egener ating the en tire mesh displa y. •To enable the eff ect of ligh ting f or the selec ted en tities on or off , selec t Ligh ting .You c an cho ose t o have ligh ting aff ect only c ertain en tities inst ead of all of them. •To toggle the filled displa y of fac es for the selec ted z ones , use the Faces option. Enabling Faces on here has the same eff ect as tur ning it on f or the en tire mesh in the Displa y Grid dialo g box. •To enable the displa y of out er edges , use the Out er F aces option. This option is useful f or displa ying both sides of a slit w all. By default , when y ou displa y a slit w all, one side will “bleed ” through t o the other .When y ou disable the Out er F aces option, the displa y of a slit w all will sho w each side distinc tly as y ou r otate the displa y.This option c an also b e useful f or displa ying t wo-sided w alls (tha t is, walls with fluid or solid c ells on b oth sides). •To enable/disable the displa y of in terior and e xterior edges of the z ones , selec t Edges . •To enable/disable the displa y of the outline of the z ones , selec t Perimet er E dges . •To enable/disable the displa y of f eature lines , selec t Feature Edges . •To enable/disable the displa y of the lines , selec t Lines . •To enable/disable the displa y of no des, selec t Nodes. 3. To overlay one displa y over another , selec t the mesh en tities in the Names selec tion list , enable Overlays in the Scene C omp osition group b ox and click Apply . Onc e overlaying is enabled , subsequen t graphics that you gener ate will b e displa yed on t op of the e xisting displa y in the ac tive gr aphics windo w.To gener ate a plot without o verlays, you must disable the Overlays option and click Apply . Note To overlay bounded c ell z ones o ver fac e zones in the displa y, do the f ollowing: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 486Examining the M esh1. Displa y only the b ounded c ell z ones (fac e zones should not b e selec ted). 2. Selec t the c ell z ones in the Names selec tion list in the Scene D escr iption dialo g box, enable Overlays and click Apply . 3. Displa y the fac e zones with the appr opriate bounds sp ecified . If you selec t the b ounded fac e zones first and enable Overlays, you will need t o deselec t the fac e zones in the Displa y Grid dialo g box before displa ying the b ounded c ell z ones . 4. To transf orm the en tities displa yed, selec t the mesh en tities in the Names selec tion list in the Scene Descr iption dialo g box and click Transf orm... to op en the Transf ormations dialo g box for the selec ted entities . •To transla te the selec ted en tities , enter the tr ansla tion distanc e in each dir ection in the X, Y, and Z r eal numb er fields under Transla te. •To rotate the selec ted en tities , enter the numb er of degr ees b y which t o rotate ab out each axis in the X,Y, and Z in teger numb er fields under Rota te By.You c an en ter an y value b etween -360 and 360. By default , the r otation or igin will b e (0,0,0). If you w ant to spin an en tity ab out its o wn or igin, or ab out some other p oint, specify the X, Y, and Z c oordina tes of tha t point under Rota te About. •To sc ale the selec ted en tities , enter the amoun t by which t o sc ale in each dir ection in the X, Y, and Z real numb er fields under Scale.To avoid dist ortion of the shap e, be sur e to sp ecify the same v alue f or all thr ee en tries. 22.5. Controlling the M ouse Butt ons You c an assign a sp ecific func tion t o each of the mouse butt ons using the Mouse Butt ons dialo g box. These func tions apply only t o the gr aphics windo ws; click ing a mouse butt on in the gr aphics windo w will c ause the appr opriate ac tion t o be tak en. Displa y → Mouse Butt ons ... Imp ortant 3DC onne xion S pace pr oduc ts (B all, Mouse , Pilot, and N aviga tor) ar e not supp orted with Fluen t. The pr edefined butt on func tions a vailable ar e as f ollows: mouse-r otate enables y ou t o rotate the view b y dr agging the mouse acr oss the scr een. •Horizontal mouse mo vemen t rotates the en tity ab out the scr een’s y-axis . •Vertical mouse mo vemen t rotates the en tity ab out the scr een’s x-axis . •The func tion c omplet es when the mouse butt on is r eleased or the cursor lea ves the gr aphics windo w. 487Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Controlling the M ouse B uttonsmouse-dolly enables y ou t o transla te the view b y dr agging the mouse while holding do wn the butt on.The func tion complet es when the mouse butt on is r eleased or the cursor lea ves the gr aphics windo w. mouse-z oom enables y ou t o dr aw a z oom b ox, anchor ed a t the p oint at which the butt on is pr essed , by dr agging the mouse .When y ou r elease the butt on: •If the dr agging w as fr om lef t to right, a magnified view of the ar ea within the z oom b ox will fill the windo w. •If the dr agging w as fr om r ight to lef t, the ar ea of the windo w shr inks t o fit in to the z oom b ox, resulting in a “zoomed out ” view . •If the mouse butt on is click ed (not dr agged), the selec ted p oint becomes the c enter of the windo w. mouse-r oll-z oom enables y ou t o zoom in or out , or r otate the mo del, by rolling the mouse while the butt on is pr essed . •If dragging up or do wn, the image is z oomed out or in, respectively. •If dragging lef t or r ight, the image is r otated ab out the scr een’s z-axis . mouse-pr obe enables y ou t o perform the sp ecified mouse pr obe func tion. The mouse pr obe func tion c an b e set in the Mouse P robe dialo g box (see Controlling the M ouse P robe Function (p.488)). mouse-annota te enables y ou t o inser t text into the gr aphics windo w. If you dr ag the mouse , an a ttachmen t line is dr awn. When y ou r elease the butt on, a cursor displa ys in the gr aphics windo w and y ou c an en ter the t ext. Press Enter or mo ve the cursor out of the gr aphics windo w. To remo ve annota ted t ext and a ttachmen t lines , selec t Clear butt on in the Annota te dialo g box. This delet es all annota ted t ext from the windo w. 22.6. Controlling the M ouse P robe Func tion You c an assign a sp ecific mouse pr obe func tion and filt er using the Mouse P robe dialo g box. Onc e set , click ing the mouse pr obe butt on in the gr aphics windo w causes the ac tion t o occur . Displa y → Mouse P robe... Use the Func tion list t o cho ose an ac tion f or the mouse pr obe butt on. off disables the mouse pr obe. label displa ys the lab el for the selec ted en tity in the gr aphics windo w. selec t enables the selec tion of an en tity by click ing.The selec ted en tity is highligh ted in the gr aphics windo w and , if op en, in a list in most dialo g boxes. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 488Examining the M eshprint prints inf ormation ab out the selec ted en tity in the c onsole . See Reporting M esh Inf ormation (p.502) for a descr iption of the output. box enables the selec tion of a gr oup of en tities within a b ox.The selec ted en tities ar e highligh ted in the graphics windo w and , if op en, in a list in most dialo g boxes.To define the selec tion b ox, click the mouse probe butt on a t one c orner of the r egion t o be selec ted, drag the mouse t o the opp osite corner, and r elease the mouse pr obe butt on. polygon enables the selec tion of a gr oup of en tities within a p olygonal r egion. The selec ted en tities ar e highligh ted in the gr aphics windo w and , if op en, in a list in most dialo g boxes.To define the selec tion p olygon, click the mouse pr obe butt on a t one v ertex of the p olygonal r egion t o be selec ted, and use the lef t mouse butt on t o succ essiv ely selec t each of the r emaining v ertices. Click the mouse pr obe butt on again (an ywher e in the gr aphics windo w) t o complet e the p olygon definition. Use the Filter selec tion list t o sp ecify the t ype of en tity selec ted.The a vailable filt ers ar e off,cell,face, edge ,node,zone ,position ,objec t, and size. Note •If off is chosen and a selec tion is made , it is first check ed t o see if it is a c ell, then a fac e, an edge , and so on. •When the node filter is used , if a c ell or fac e is selec ted the no de closest t o the selec tion p oint is pick ed.Thus no des do not ha ve to be displa yed t o be pick ed. When using box selec t or polygon selec t, by default , all en tities will b e selec ted.To selec t only visible entities (no des, faces, zones , objec ts) inst ead, enable Selec t Visible E ntities in the Mouse P robe Func tion group in the r ibbon.The selec tion will then include only en tities visible t o the e ye, and not those hidden b ehind other en tities in the displa y.When enabled , ensur e tha t the mo del is z oomed t o an appr opriate level for c orrect selec tion. Note •If the mesh is not c onnec ted, all en tities (no des, edges , faces, zones , objec ts) will b e selec ted irrespective of whether the y are visible or not. •This visual selec tion b ehavior w orks only on lo cal displa ys and ma y gener ate warning mes- sages when a ttempting selec tion on a r emot e sy stem. 22.7. Annota ting the D ispla y Text annota tions with optional a ttachmen t lines ma y be added t o the gr aphics windo ws. Displa y → Annota te... 489Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Annota ting the D ispla yThe t ext is added t o the windo w at a lo cation chosen with the mouse , using the mouse-pr obe butt on (see Controlling the M ouse B uttons (p.487) for inf ormation on setting the mouse butt ons). Dragging with the mouse-pr obe butt on pr essed will dr aw an a ttachmen t line fr om the p oint wher e the mouse was first click ed t o the p oint wher e it w as released .The annota tion t ext will b e plac ed a t the p oint wher e the mouse butt on w as released . The annota tion t ext is asso ciated with the ac tive gr aphics windo w; it is r emo ved only when the annota- tions ar e explicitly clear ed.You c an edit the t ext in the gr aphics windo w’s caption blo ck b y the lef t mouse butt on in the desir ed lo cation. When a cursor app ears , you c an t ype the new t ext or delet e the existing t ext.Text in the c aption blo ck will not be delet ed when y ou clear annota tions . 22.8. Setting D efault C ontrols The Displa y → Controls menu it em op ens the Controls dialo g box to set file-sp ecific v ariables c alled tgvars . The dialo g box has t wo comp onen ts: the Categor ies drop-do wn list and the ac tual v ariables asso ciated with tha t categor y. Selec t the desir ed c ategor y, and then en ter the desir ed default v alues . Click Apply to up date your file with the new v alues . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 490Examining the M eshChapt er 23: Determining M esh S tatistics and Q ualit y The b est w ay to det ermine the qualit y of a mesh is b y looking a t sta tistics such as maximum sk ewness , rather than just p erforming a visual insp ection. Unlike str uctured meshes , unstr uctured meshes ar e near ly imp ossible t o compr ehend with only a gr aphic al plot. The Rep ort menu has a v ariety of r eporting capabilities .The t ypes of mesh inf ormation tha t can b e reported include: •The siz e of the mesh (tha t is, the numb er of no des, faces, and c ells in it): use the Rep ort Mesh S ize dialo g box. Rep ort → Mesh S ize... •Minimum, maximum, and a verage v alues of fac e siz e and qualit y: use the Rep ort Face Limits dialo g box. Rep ort → Face Limits ... •Minimum, maximum, and a verage v alues of c ell siz e and qualit y in a v olume mesh: use the Rep ort Cell Limits dialo g box.The default qualit y measur e is sk ewness , but y ou c an also r eport the limits based on other qualit y measur es or the r ange of change in c ell siz e. Rep ort → Cell Limits ... •Boundar y cell qualit y limits: use the Rep ort Boundar y Cell Limits dialo g box. Rep ort → Boundar y Cell Limits ... •Information ab out individual c omp onen ts of the mesh: use the print-info command . Imp ortant If you used domains t o gener ate the mesh or gr oup z ones f or reporting (as descr ibed in Using D omains t o Group and M esh B oundar y Faces (p.468)), the r eport will apply only t o the active domain. These r eporting op erations ar e descr ibed in the f ollowing sec tions . 23.1. Determining M esh S tatistics 23.2. Determining M esh Q ualit y 23.3. Reporting M esh Inf ormation 23.1. Determining M esh S tatistics The Rep ort Mesh S ize dialo g box reports the numb er of no des, faces, and c ells. Nodes and fac es ar e group ed in to those defining the b oundar ies and those used inside c ell z ones . Click Update to view the latest mesh sta tistics . If the gener ation of the initial mesh fails , you c an det ermine the numb er of meshed b oundar y no des and fac es b y enabling Rep ort Numb er M eshed in the Rep ort Mesh S ize dialo g box.The headings Bound- 491Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.ary and Interior will b e replac ed b y Total and Meshed , respectively, and the t otal numb er of b oundar y nodes and fac es will b e reported along with the numb er tha t were meshed . 23.2. Determining M esh Q ualit y A go od qualit y mesh guar antees the b est analy sis r esults f or the pr oblem, minimiz es the need f or addi- tional analy sis r uns, and impr oves y our pr edic tive capabilities .The mesh should b e fine enough t o resolv e the pr imar y features of the pr oblem b eing analyz ed.The mesh r esolution dep ends on the b oundar y mesh fr om which y ou star t and the par amet ers c ontrolling the gener ation of the in terior mesh. In a high-qualit y mesh, the change in siz e from one fac e or c ell t o the ne xt should b e minimiz ed. Large differences in siz e between adjac ent fac es or c ells will r esult in a p oor c omputa tional mesh b ecause the diff erential equa tions b eing solv ed assume tha t the c ells shr ink or gr ow smo othly . 23.2.1. Determining Sur face Mesh Q ualit y 23.2.2. Determining Volume M esh Q ualit y 23.2.3. Determining B oundar y Cell Q ualit y 23.2.4. Qualit y Measur e 23.2.1. Determining S urface M esh Q ualit y Before gener ating a v olume mesh, check the qualit y of the fac es to get an indic ation of the o verall mesh qualit y.To check fac e siz e and qualit y limits , use the Rep ort > F ace Limits ... dialo g box. For 3D meshes , a maximum of less than 0.9 and an a verage of 0.4 ar e go od.The lo wer the maximum sk ewness , the b etter the mesh. See Qualit y Measur e (p.494) for inf ormation on fac e and c ell qualit y measur es available . The default qualit y measur e is sk ewness , but y ou c an also r eport other qualit y measur es such as the aspect ratio limits or the r ange in siz e change f or a fac e zone . Before creating a la yer of p yramid c ells, check the asp ect ratio of the quadr ilateral fac es tha t will f orm the base of the p yramids .This asp ect ratio should b e less than 8, other wise the tr iangular fac es of the p yramids will b e highly sk ewed. If the aspect ratio is gr eater than 8, regener ate the quadr ilateral fac es: •If the quadr ilateral fac es w ere created in a diff erent preprocessor , retur n to tha t applic ation and tr y to reduc e the asp ect ratio of the fac es in question. •If the quadr ilateral fac es w ere created dur ing the building of pr ism la yers, rebuild the pr isms using a mor e gradual gr owth r ate. Check the sk ewness of tr iangular fac es on a b oundar y from which y ou ar e going t o build pr isms t o ensur e tha t the qualit y of the pr ism c ells will b e go od. After y ou cr eate the pr isms , check the sk ewness of the tr iangular fac es tha t were created dur ing the pr ism gener ation. Face Distribution hist ogram When check ing the qualit y of the mesh y ou ma y find it useful t o lo ok a t a hist ogram of b oundar y fac e qualit y or siz e.You c an gener ate such a plot or r eport using the Face D istribution dialo g box. Displa y → Plot → Face D istribution The numb er of fac es on the selec ted z ones with a siz e or qualit y measur e value (e .g., skewness) in the specified r ange in each of the r egular ly spac ed par titions is displa yed in a hist ogram f ormat.The x axis sho ws the siz e or qualit y and the y axis giv es the numb er of fac es or the p ercentage of the t otal numb er of fac es. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 492Determining M esh S tatistics and Q ualit yYou c an mo dify the app earance of the hist ogram using the options a vailable in the Axes dialo g box. The f ollowing par amet ers c an b e mo dified: •Labels f or the ax es. •Scaling of the ax es: decimal (default) or lo garithmic . •Range of v alues: enable Auto Range or sp ecify minimum and maximum v alues . •Major and minor r ules: hor izontal or v ertical lines mar king the pr imar y and sec ondar y da ta divisions , respectively.You c an selec t the line c olor and thick ness t o be used . •Numb er format. You c an also mo dify the app earance of the hist ogram using the options a vailable in the Curves dialo g box.The f ollowing par amet ers c an b e mo dified: •Line st yle pa tterns, colors , and w eigh t. •Marker symb ols, colors , and st yles . When the hist ogram plot is displa yed in the gr aphics windo w, you c an use an y of the mouse butt ons to add t ext annota tions t o the plot. See Controlling the M ouse B uttons (p.487) and Annota ting the Displa y (p.489) for mor e inf ormation ab out using the mouse butt ons and annota tion f eatures. 23.2.2. Determining Volume M esh Q ualit y After gener ating the v olume mesh, check the qualit y of the c ells t o get an indic ation of o verall mesh qualit y.The qualit y of the mesh pla ys a signific ant role in the accur acy and stabilit y of the numer ical computa tion. To check c ell siz e and qualit y limits , use the Rep ort > C ell Limits ... dialo g box. The default qualit y measur e is sk ewness , but y ou c an also r eport other qualit y measur es such as the aspect ratio limits or the r ange in siz e change f or a c ell z one . See Qualit y Measur e (p.494) for inf ormation on fac e and c ell qualit y measur es a vailable . Cell D istribution hist ogram You c an gener ate a hist ogram plot t o gr aphic ally displa y cell siz e or qualit y by using the c ontrols in the Cell D istribution dialo g box. Displa y → Plot → Cell D istribution The numb er of c ells in the selec ted z ones with a siz e or qualit y value (e .g., skewness) in the sp ecified range in each of the r egular ly spac ed par titions is displa yed in a hist ogram f ormat.The x axis sho ws either the siz e or the qualit y and the y axis giv es the numb er of c ells or the p ercentage of the t otal. You c an mo dify the app earance of the hist ogram using the options a vailable in the Axes dialo g box. The f ollowing par amet ers c an b e mo dified: •Labels f or the ax es. •Scaling of the ax es: decimal (default) or lo garithmic . •Range of v alues: enable Auto Range or sp ecify minimum and maximum v alues . 493Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Determining M esh Q ualit y•Major and minor r ules: hor izontal or v ertical lines mar king the pr imar y and sec ondar y da ta divisions , respectively.You c an selec t the line c olor and thick ness t o be used . •Numb er format. You c an also mo dify the app earance of the hist ogram using the options a vailable in the Curves dialo g box.The f ollowing par amet ers c an b e mo dified: •Line st yle pa tterns, colors , and w eigh t. •Marker symb ols, colors , and st yles . When the hist ogram plot is displa yed in the gr aphics windo w, you c an use an y of the mouse butt ons to add t ext annota tions t o the plot. For mor e inf ormation ab out the annota tion f eatures, see Controlling the M ouse B uttons (p.487) and Annota ting the D ispla y (p.489). 23.2.3. Determining B oundar y Cell Q ualit y For b oundar y layer flo ws, boundar y cells with lo w sk ewness ar e very imp ortant. Use the Rep ort Boundar y Cell Limits dialo g box to report the qualit y of c ells c ontaining a sp ecified numb er of boundar y fac es or no des. For tetrahedr al meshes , the maximum sk ewness will not b e lower than the maximum fac e sk ewness , because the b oundar y cell sk ewness is limit ed b y the b oundar y fac e sk ewness . You c an r emo ve highly sk ewed c ells with t wo boundar y fac es b y using the Tet Impr ove dialo g box. Mesh → Tools → Tet Impr ove... 23.2.4. Qualit y M easur e To sp ecify the qualit y measur e (sk ewness , asp ect ratio, change in siz e, and so on), use the Qualit y Measur e dialo g box.The default qualit y measur e is sk ewness . Rep ort → Qualit y M easur e... Mesh qualit y is det ermined b y the f ollowing qualit y measur es: Skewness Skewness is one of the pr imar y qualit y measur es for a mesh. Skewness det ermines ho w close t o ideal (tha t is, equila teral or equiangular) a fac e or c ell is: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 494Determining M esh S tatistics and Q ualit yFigur e 23.1: Ideal and S kewed Triangles and Q uadr ilaterals The f ollowing table lists the r ange of sk ewness v alues and the c orresponding c ell qualit y. Table 23.1: Skewness R anges and C ell Q ualit y Cell Q ualit y Skewness degener ate 1 bad (sliv er) 0.9–<1 poor 0.75–0.9 fair 0.5–0.75 good 0.25–0.5 excellen t >0–0.25 equila teral 0 According t o the definition of sk ewness , a value of 0 indic ates an equila teral cell (b est qualit y) and a value of 1 indic ates a c omplet ely degener ate cell. Degener ate cells (sliv ers) ar e char acterized b y nodes tha t are near ly coplanar . Cells with a sk ewness v alue ab ove 1 ar e invalid. Highly sk ewed fac es and c ells should b e avoided b ecause the y can lead t o less accur ate results than when r elatively equila teral/equiangular fac es and c ells ar e used . Two metho ds for measur ing sk ewness ar e: •Based on the equila teral volume (applies only t o tetrahedr a). 495Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Determining M esh Q ualit y•Based on the de viation fr om a nor maliz ed equila teral angle .This metho d applies t o all c ell and fac e shap es, such as p yramids and pr isms . The default sk ewness metho d for tetrahedr a is the equila teral volume metho d, but y ou c an change to the angle de viation metho d using the Qualit y M easur e dialo g box. Equila teral-V olume-B ased S kewness In the equila teral volume de viation metho d, skewness is defined as (23.1) wher e, the optimal c ell siz e is the siz e of an equila teral cell with the same cir cumr adius . In 3D meshes , most c ells should b e rated go od or b etter, but a small p ercentage will gener ally b e in the fair r ange and ther e ar e usually e ven a f ew p oor c ells.The pr esenc e of p oor c ells c an indic ate poor b oundar y no de plac emen t.You should tr y to impr ove your b oundar y mesh as much as p ossible because the qualit y of the o verall mesh c an b e no b etter than tha t of the b oundar y mesh. Normaliz ed E quiangular S kewness In the nor maliz ed angle de viation metho d, skewness is defined (in gener al) as (23.2) wher e = lar gest angle in the fac e or c ell = smallest angle in the fac e or c ell = angle f or an equiangular fac e/cell (such as 60 f or a tr iangle , 90 f or a quad , and so on) The c ell sk ewness will b e the maximum sk ewness c omput ed f or an y fac e. For e xample , an ideal pyramid (sk ewness = 0) is one in which the 4 tr iangular fac es ar e equila teral (and equiangular) and the quadr ilateral base fac e is a squar e.The guidelines in Table 23.1: Skewness R anges and C ell Qualit y (p.495) apply t o the nor maliz ed equiangular sk ewness as w ell. Size Change Size change is the r atio of the ar ea (or v olume) of a fac e (or c ell) in the geometr y to the ar ea (or v olume) of each neighb oring fac e (or c ell). This r atio is c alcula ted f or e very fac e (or c ell) in the domain. The minimum and maximum v alues ar e reported f or the selec ted z ones . Edge R atio The edge r atio is defined as the r atio of maximum length of the edge of the elemen t to the minimum length of the edge of the elemen t. By definition, edge r atio is alw ays greater than or equal t o 1. The higher the v alue of the edge r atio, the less r egular ly shap ed is its asso ciated elemen t. For equila teral elemen t shap es, the edge r atio is alw ays equal t o 1. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 496Determining M esh S tatistics and Q ualit yAspect Ratio The asp ect ratio of a fac e or c ell is the r atio of the longest edge length t o the shor test edge length. The aspect ratio applies t o triangular , tetrahedr al, quadr ilateral, and he xahedr al elemen ts and is defined dif- ferently for each elemen t type. The asp ect ratio c an also b e used t o det ermine ho w close t o ideal a fac e or c ell is . •For an equila teral fac e or c ell (such as an equila teral tr iangle , a squar e, and so on), the asp ect ratio is 1. •For less r egular ly-shap ed fac es or c ells, the asp ect ratio will b e gr eater than 1 as the edges diff er in length. •For tr iangular fac es and t etrahedr al cells and f or p yramids , you c an usually f ocus on impr oving the skewness , and the smo othness and asp ect ratio will c onsequen tly b e impr oved as w ell. •For pr isms , it is imp ortant to check the asp ect ratio and/or the change in siz e in addition t o the sk ewness , because it is p ossible t o ha ve a lar ge jump in c ell siz e between t wo cells with lo w sk ewness or a high- aspect-ratio lo w-sk ew c ell. Squish Squish is a measur e used t o quan tify the non-or thogonalit y of a c ell with r espect to its fac es. It is defined as follows: (23.3) wher e A = fac e unit ar ea v ector = the v ector c onnec ting the adjac ent cell c entroids (f or fac e squish) or the c ell and fac e centroids (for c ell squish) Warp (Q uadr ilateral E lemen ts only) Face warp applies only t o quadr ilateral elemen ts and is defined as the v ariation of nor mals b etween the two triangular fac es tha t can b e constr ucted fr om the quadr ilateral fac e.The ac tual v alue is the maximum of the t wo possible w ays triangles c an b e created. Mathema tically, it is e xpressed as f ollows: (23.4) wher e = the de viation fr om a b est-fit plane tha t contains the elemen t , = the lengths of the line segmen ts tha t bisec t the edges of the elemen t The v alue of fac e warp ranges b etween 0 and 1. A v alue of 0 sp ecifies an equila teral elemen t and a value of 1 sp ecifies a highly sk ewed elemen t. Dihedr al A ngle Dihedr al angle applies only t o fac es and not c ells.The dihedr al angle is defined as the angle b etween the normals of adjac ent fac es.This qualit y measur e is useful in lo cating shar p corners in c omplic ated geomet- ries.The dihedr al angle v alue r anges fr om 0–180. 497Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Determining M esh Q ualit yICEM CFD Q ualit y The ICEM CFD qualit y measur e calcula tes elemen t qualit y based on the qualit y values in ANSY S ICEM CFD .This measur e is only a vailable f or c ells, not fac es. •Tetrahedr a:The qualit y is c alcula ted as the sk ewness of the t etrahedr al elemen t. The r emaining qualit y values ar e based on v arious qualit y metr ics c omput ed in ANSY S ICEM CFD . Qualit y = 1 - ANSY S ICEM CFD Q ualit y •Hexahedr a:The qualit y is based on the D eterminan t, Max Or thogls, and M ax Warpgls metr ics in ANSY S ICEM CFD . –The det erminan t is the r atio of the smallest and the lar gest det erminan t of the Jac obian ma trices, wher e a Jac obian ma trix is c omput ed a t each no de of the elemen t. –The max or thogls metr ic calcula tes the maximum de viation of the in ternal angles of the elemen t from 90 degr ees. Angles b etween 180 and 360 degr ees (de viation up t o 270 degr ees) will also b e consider ed. –The w arp for each fac e is c alcula ted as the maximum angle b etween the tr iangles c onnec ted a t the diagonals of the fac e.The max w arpgls metr ic is c alcula ted as the maximum w arp of the fac es c om- prising the elemen t. These v alues ar e nor maliz ed and the minimum v alue of the thr ee nor maliz ed diagnostics will be used . •Pyramids: The qualit y is based on the D eterminan t comput ed in ANSY S ICEM CFD . The det erminan t is the r atio of the smallest and the lar gest det erminan t of the Jac obian ma trices, wher e a Jac obian ma trix is c omput ed a t each no de of the elemen t. •Prisms: The qualit y is based on the D eterminan t and Warp comput ed in ANSY S ICEM CFD . –The det erminan t is the r atio of the smallest and the lar gest det erminan t of the Jac obian ma trices, wher e a Jac obian ma trix is c omput ed a t each no de of the elemen t. –The w arp for each fac e is c alcula ted as the maximum angle b etween the r espective edges and a plane c ontaining the mid-p oints of the edges c ompr ising the fac e.The w arp for the elemen t is then calcula ted as the maximum w arp of the fac es c ompr ising the elemen t. The qualit y is c alcula ted as the minimum of the det erminan t and w arp. For fur ther details on the qualit y measur es a vailable in ANSY S ICEM CFD , refer to the ANSY S ICEM CFD H elp M anual. The r ange of qualit y values r eported is b etween 0-2 (the r ange in ANSY S ICEM CFD is -1 t o 1, and a value of 2 c orresponds t o -1 in ANSY S ICEM CFD , 1 to 0, and 0 t o 1, respectively). A v alue of 0 indic ates a p erfect, non-dist orted elemen t, 1 indic ates a degener ate elemen t, and v alues ab ove 1 indic ate an in valid elemen t (such as c oncave, dihedr al angle > 180 degr ee, or nega tive volume elemen ts). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 498Determining M esh S tatistics and Q ualit yOrtho S kew The or tho sk ew qualit y for a c ell is c omput ed using the fac e nor mal v ector, for each fac e; the v ector from the c ell c entroid t o the c entroid of each of the adjac ent cells, ; and the v ector fr om the c ell c entroid to the c entroid of each fac e, .Figur e 23.2: Vectors U sed t o Comput e Or tho S kew/In verse Or thogonal Qualit y for a C ell (p.499) illustr ates the v ectors used t o det ermine the or tho sk ew qualit y for a c ell. Figur e 23.2: Vectors U sed t o Comput e Or tho S kew/In verse Or tho gonal Q ualit y for a C ell For each fac e , the c alcula tion first finds the v alue of (1 - the c osine of the angle b etween the fac e normal v ector and the c orresponding v ector fr om the c entroid of the c ell t o the c entroid of tha t face): (23.5) Next, for each fac e , the c alcula tion finds the v alue of (1 - the c osine of the angle b etween the face nor mal v ector and the c orresponding v ector fr om the c entroid of the c ell t o the c entroid of the adjac ent cell tha t shar es tha t fac e): (23.6) The r eported Or tho S kew qualit y for a c ell then dep ends on the c ell t ype: •For most c ells, Ortho S kew is the maximum of the ab ove quan tities c omput ed f or each fac e. •For p yramid c ells, Ortho S kew is the maximum of the c ell sk ewness and the ab ove quan tities comput ed f or each fac e. Note •When the c ell is lo cated on the b oundar y, the v ector across the b oundar y fac e is ignor ed during the qualit y computa tion. 499Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Determining M esh Q ualit y•When the c ell is separ ated fr om the adjac ent cell b y an in ternal w all, the v ector across the in ternal b oundar y fac e is ignor ed dur ing the qualit y computa tion. •When the adjac ent cells shar e a par ent-child r elation, the v ector is the v ector fr om the cell c entroid t o the c entroid of the child fac e while the v ector is the v ector fr om the c ell centroid t o the c entroid of the adjac ent child c ell shar ing the child fac e. The or tho sk ew qualit y for fac es is similar ly comput ed using the edge nor mal v ector, , and the vector fr om the fac e centroid t o the c entroid of each edge , .Figur e 23.3: Vectors U sed t o Comput e Ortho S kew Q ualit y for a F ace (p.500) illustr ates the v ectors used t o det ermine the or tho sk ew qualit y for a fac e. Figur e 23.3: Vectors U sed t o Comput e Or tho S kew Q ualit y for a F ace The or tho sk ew f or a fac e is the maximum of the c omput ed v alues f or (1 - the c osine of the angle between the edge nor mal v ector and the v ector fr om the c entroid of the fac e to the c entroid of the edge), for each edge : (23.7) Fluen t Aspect Ratio The F luen t asp ect ratio is a measur e of the str etching of a c ell. It is c omput ed as the r atio of the maximum value t o the minimum v alue of an y of the f ollowing distanc es: the nor mal distanc es b etween the c ell centroid and fac e centroids , and the distanc es b etween the c ell c entroid and no des. For a unit cub e (see Figur e 23.4: Calcula ting the F luen t Aspect Ratio f or a U nit C ube (p.501)), the maximum distanc e is 0.866, and the minimum distanc e is 0.5, so the asp ect ratio is 1.732. This t ype of definition c an b e applied on any type of mesh, including p olyhedr al. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 500Determining M esh S tatistics and Q ualit yFigur e 23.4: Calcula ting the F luen t Aspect Ratio f or a U nit C ube Inverse Or tho gonal Q ualit y The in verse or thogonal qualit y for a c ell is c omput ed using the fac e nor mal v ector, for each fac e; the vector fr om the c ell c entroid t o the c entroid of each of the adjac ent cells, ; and the v ector fr om the c ell centroid t o the c entroid of each fac e, (see Figur e 23.2: Vectors U sed t o Comput e Or tho S kew/In verse Orthogonal Q ualit y for a C ell (p.499)). For each fac e, the c osines of the angle b etween and , and between and are calcula ted.The smallest c alcula ted c osine v alue is the or thogonalit y of the c ell. Then, inverse or thogonalit y is f ound b y subtr acting this c osine v alue fr om 1. Finally ,Inverse Or tho gonal Q ualit y dep ends on c ell t ype: •For tetrahedr al, prism, and p yramid c ells, Inverse Or thogonal Q ualit y is the maximum of the c ell skewness and the in verse or thogonalit y. •For he xahedr al and p olyhedr al cells, Inverse Or thogonal Q ualit y is the same as the in verse or tho- gonalit y. The w orst c ells will ha ve an In verse Or thogonal Q ualit y closer t o 1 and the b est c ells will ha ve an Inverse Or thogonal Q ualit y closer t o 0. Note Inverse Or tho gonal Q ualit y = 1 - Ortho gonal Q ualit y Ortho gonal Q ualit y can b e reported using the Qualit y option in the r ibbon or the Rep ort Qualit y butt on in the Gener al task page in solution mo de (r efer to Mesh Qualit y (p.719) for details). 501Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Determining M esh Q ualit y23.3. Rep orting M esh Inf ormation The mouse pr obe print func tion displa ys inf ormation ab out individual c omp onen ts of the mesh. The type of inf ormation is det ermined b y the selec ted mouse pr obe filt er. The print-info command r eports inf ormation ab out an individual mesh en tity (tha t is, a no de, face, or c ell). In some cir cumstanc es, the inf ormation includes pr efixes or punc tuation t o iden tify the inf orm- ation t ype. An en tity is iden tified b y its pr efix with an inde x value .Valid pr efixes ar e:bn (boundar y node),n (no de),bf (boundar y fac e),f (fac e), and c (cell). Hence, the first b oundar y no de w ould b e bn1 . The output f or some of the en tity types is as e xplained in this sec tion. cell The f ollowing inf ormation is list ed f or a c ell: •zone ID •the no des f orming the c ell •the fac es forming the c ell •the siz e •the c oordina tes of the cir cumc enter (r elevant for tetrahedr al cells only) •squar e of the cir cumc enter radius (r elevant for tetrahedr al cells only) •the qualit y of the c ell c26 = (1 (n262 n34 bn204 bn205) (f4743 f5372 f1822 f3426) 0.00020961983 (2.7032523 0.32941867 0.072823988) 0.0081779587 0.44769606) The default measur e of qualit y is sk ewness , but y ou c an use the Qualit y M easur e dialo g box to sp ecify aspect ratio or change in siz e inst ead. face The f ollowing inf ormation is list ed f or a fac e: •asso ciated z one ID •the no des f orming the fac e •the neighb oring c ells f32 = (4 (n95 bn197 n90) (c4599 c1279)) Due t o the manner in which the algor ithm main tains memor y, not all indic es will ha ve values—tha t is, an empt y slot c an b e caused b y a delet e op eration. Empt y slots ar e reused in subsequen t op erations , so the ac tual en tity at a par ticular inde x ma y change as the mesh is gener ated. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 502Determining M esh S tatistics and Q ualit yboundar y fac e The f ollowing inf ormation is list ed f or a b oundar y fac e: •asso ciated z one ID •the no des f orming the fac e •the neighb oring c ells •the p eriodic shado w (null if not p eriodic) •the qualit y of the fac e bf17 = (2 (bn1308 bn1314 bn1272) (() c1533) () 0.014393554) The default measur e of qualit y is sk ewness , but y ou c an use the Qualit y M easur e dialo g box to sp ecify aspect ratio or change in siz e inst ead. node The f ollowing inf ormation is list ed f or a no de: •asso ciated z one ID •Cartesian c oordina tes of the no de •the no de r adius n30 = (5 (2.433799 0.078610075 0.52846689) 0.12702106) For in terior no des, the no de r adius is the distanc e-weigh ted a verage t o the sur rounding no des. boundar y no de The f ollowing inf ormation is list ed f or the b oundar y no de: •asso ciated z one ID •Cartesian c oordina tes of the no de •node r adius •faces using the no de. bn1 = (3 (0 0 0) 0.1 (bf2099 bf1093 bf193)) For b oundar y no des, the no de r adius is the a verage distanc e to neighb oring b oundar y no des. 503Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Reporting M esh Inf ormationRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 504Appendix A. Imp orting B oundar y and Volume M eshes The v olume-mesh gener ation scheme r equir es sets of tr iangular and/or quadr ilateral elemen ts defining the b oundar ies of the c omputa tional domain. In addition t o the basic c apabilit y pr ovided in GAMBIT , Fluen t can use other p opular C AD/C AE sof tware pack ages . A.1. GAMBIT M eshes A.2. TetraMesher Volume M esh A.3. Meshes fr om Third-Party CAD P ackages A.1. GAMBIT M eshes GAMBIT c an cr eate both sur face and v olume meshes . See the GAMBIT M odeling G uide f or details . A.2. TetraMesher Volume M esh ICEM CFD Engineer ing wr ites a R AMP ANT file fr om TetraMesher .TetraMesher gener ates tetrahedr al volume gr ids using a r ecursiv e sub division o ctree scheme . To read a R AMP ANT file , use the File → Read → Mesh menu it em or the file/read-mesh text command . A.3. Meshes fr om Third-Party CAD P ack ages You c an imp ort grid files fr om thir d-par ty CAD pack ages b y using the it ems in the File → Imp ort menu . Alternatively, the fe2ram filter enables y ou t o convert files cr eated b y se veral finit e-elemen t pack ages to the gr id file f ormat used b y Fluen t.You c an c onvert sur face or v olume meshes fr om ANSY S, I-deas , NASTR AN, PATRAN, VRML files fr om VRML v ersion 1.0, or other pack ages . ARIES files c an b e converted only if the y are first sa ved as ANSY S Prep7 files , as descr ibed in ARIES F iles (p.509). If you cho ose t o convert the file manually b efore reading it , enter the f ollowing c ommand: utility fe2ram [ dimension ] read-format [merge] [zoning] [write-format ] input-file output-file The it ems in squar e br ackets ar e optional. •dimension indic ates the dimension of the da taset. –For a 3D gr id, do not sp ecify dimension as 3D is the default. –For a 2D gr id, replac e dimension by -d2 . –For a sur face mesh, replac e dimension by -surface . •read-format indic ates the f ormat of the file y ou w ant to convert. Replac e read-format as f ollows: –For an ANSY S file , use -tANSYS . 505Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.–For an I-deas file , use -tIDEAS . –For a NASTR AN file , use -tNASTRAN . –For a P ATRAN file , use -tPATRAN . For a list of c onversion c apabilities fr om other C AD pack ages , type utility fe2ram -cl -help . •merge indic ates the gr id toler ance.The default is 10-6 (1.0e-06 ).To set another t oler ance value , replac e mer ge b y -mTOLERANCE , wher e TOLERANCE is an appr opriate real numb er value .To reset the t oler ance to the default v alue , replac e merge by -m. •zoning indic ates ho w zones w ere iden tified in the C AD pack age. Replac e zoning as f ollows: –For a gr id zoned b y gr oup , do not sp ecify zoning as z oning b y gr oups is the default. –For a gr id tha t was zoned b y pr operty IDs , use -zID . –To ignor e all z one gr oupings , use -zNONE . •write-format indic ates the output f ormat for the file y ou w ant to convert. Replac e write-format as follows: –To wr ite the gr id for use in F luen t, do not sp ecify write-format as this is the default. –To wr ite the gr id in FIDAP format, use -oFIDAP7 . •input-file and output-file are the names of the or iginal file and the file t o which y ou w ant to wr ite the c onverted gr id inf ormation, respectively. For e xample , to convert the 2D I-deas v olume mesh file sample.unv to an output file c alled sample.msh , enter: utility fe2ram -d2 -tIDEAS sample.unv sample.msh After the output file has b een wr itten, you c an r ead it using File → Imp ort in the meshing mo de of Fluen t. For v olume meshes , the r esulting output file c an also b e read in to the solution mo de of F luen t. Imp ortant All boundar y types ar e consider ed t o be wall z ones .You c an set the appr opriate boundar y types in meshing mo de or in solution mo de. Note The f e2ram utilit y supp orts VRML files fr om VRML v ersion 1.0. A.3.1. I-deas U niversal F iles For I-deas sur face meshes , the filt er reads tr iangular and quadr ilateral elemen ts tha t define the boundar ies of the domain and ha ve been gr oup ed within I-deas t o cr eate zones . For v olume meshes , the filt er reads a 2D or 3D mesh tha t has its b oundar y no des or 2D b oundar y elemen ts appr opriately Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 506Imp orting B oundar y and Volume M eshesgroup ed t o cr eate boundar y zones . Do not include no des and b oundar y elemen ts in the same gr oup . All boundar y zones will b e consider ed w all z ones; you c an set the appr opriate boundar y types in the meshing mo de or in the solution mo de. See Meshes fr om Third-Party CAD P ackages (p.505) for fur ther details . A.3.1.1. Recogniz ed I-deas D atasets The f ollowing U niversal file da tasets ar e recogniz ed b y the gr id filt er: Node C oordina tes dataset numb er 15, 781, 2411 Elemen ts dataset numb er 780 or 2412 Permanen t Groups dataset numb er 752, 2417, 2429, 2430, 2432, 2435 Because F luen t uses linear elemen ts, you should use linear elemen ts to gener ate the gr id inside the mesh ar eas. If par abolic elemen ts exist in the da taset , the filt er ignor es the mid side no des.This as- sumption is v alid if the edges of the elemen t are near linear . However, if this is not the c ase, an inc or- rect topology ma y result fr om this assumption. For e xample , in r egions of high cur vature the par abolic elemen t ma y look much diff erent than the linear elemen t. For v olume meshes , not e tha t mesh ar ea/mesh v olume da tasets ar e not recogniz ed.This implies tha t writing multiple mesh ar eas/mesh v olumes t o a single U niversal file ma y confuse fe2ram or F luen t. A.3.1.2. Grouping Elements t o Creat e Zones for a S urface Mesh The G roup c ommand in I-deas is used t o cr eate the b oundar y zones needed b y Fluen t. All fac es group ed t ogether ar e list ed t ogether in the output as a single z one . In F luen t, boundar y conditions are set on a p er-zone basis . One t echnique is t o gener ate gr oups aut oma tically based on mesh ar eas—tha t is, every mesh ar ea will b e a diff erent zone . Although this metho d ma y gener ate a lar ge numb er of z ones , the z ones c an be mer ged in the meshing mo de or in the solution mo de of F luen t. Another t echnique is t o cr eate a gr oup of elemen ts related t o a giv en mesh ar ea manually .This enables y ou t o selec t multiple mesh areas f or one gr oup . A.3.1.3. Grouping N odes t o Creat e Zones for a Volume Mesh The G roup c ommand is used in I-deas t o cr eate the b oundar y zones needed b y Fluen t. All no des group ed t ogether ar e list ed t ogether in the output as a single z one . It is imp ortant not t o gr oup nodes of in ternal fac es with no des of b oundar y fac es. One t echnique is t o gener ate gr oups aut oma tically based on cur ves or mesh ar eas—tha t is, every curve or mesh ar ea will b e a diff erent zone in F luen t. Another t echnique is t o cr eate the gr oups manually , gener ating gr oups c onsisting of all no des r elated t o a giv en mesh ar ea (3D). 507Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Meshes fr om Third-Party CAD P ackagesA.3.1.4. Perio dic B oundaries In gener al, it is difficult t o gener ate a v alid gr id with p eriodic b oundar ies in I-deas . However, a sp ecial feature exists in the meshing mo de in F luen t tha t enables y ou t o gener ate a gr id in a domain with periodic b oundar ies. See Creating P eriodic B oundar ies (p.320) for fur ther details . A.3.1.5. Deleting D uplic ate Nodes I-deas of ten gener ates duplic ate no des in the pr ocess of cr eating tr iangular elemen ts.These must b e remo ved b y using either the r emo ve coinciden t no de c ommand in I-deas or the Merge butt on in the Merge B oundar y Nodes dialo g box (or the /boundary/merge-duplicates text command). This no de mer ging pr ocess is usually fast er in the meshing mo de in F luen t but mor e visual in I-deas . A.3.2. PATRAN N eutr al Files For P ATRAN sur face meshes , the filt er reads tr iangular and quadr ilateral linear elemen ts tha t define the b oundar ies of the domain and ha ve been gr oup ed b y named c omp onen t or iden tified b y pr operty IDs within P ATRAN t o cr eate zones . For v olume meshes , the filt er reads a 2D or 3D mesh tha t has its boundar y no des gr oup ed b y named c omp onen t to cr eate boundar y zones . All boundar y zones will be consider ed w all z ones; you c an set the appr opriate boundar y types in the meshing mo de or in the solution mo de of F luen t. See Meshes fr om Third-Party CAD P ackages (p.505) for details . A.3.2.1. Recogniz ed P ATRAN D atasets The f ollowing N eutr al file da tasets ar e recogniz ed b y the gr id filt er: Node D ata Packet Type 01 Elemen t Data Packet Type 02 Distribut ed L oad D ata Packet Type 06 Node Temp erature Data Packet Type 10 Name C omp onen ts Packet Type 21 File H eader Packet Type 25 A.3.2.2. Grouping Elements t o Creat e Zones In PATRAN, named c omp onen ts ar e applied t o the no des t o cr eate gr oups of fac es c alled z ones . In Fluen t, boundar y conditions ar e applied t o each z one . For e xample , all no des on a cur ve or pa tch can b e put in a N ame C omp onen t. For 2D v olume meshes , an additional c onstr aint is plac ed on the elemen ts: existence in the Z=0 plane . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 508Imp orting B oundar y and Volume M eshesA.3.2.3. Perio dic B oundaries In gener al, it is difficult t o gener ate a v alid gr id with p eriodic b oundar ies in P ATRAN. However, a special f eature exists in the meshing mo de in F luen t tha t enables y ou t o gener ate a gr id in a domain with p eriodic b oundar ies. See Creating P eriodic B oundar ies (p.320) for fur ther details . A.3.3. ANSY S Files For ANSY S sur face meshes , the filt er reads tr iangular and quadr ilateral linear elemen ts tha t define the boundar ies of the domain and ha ve been gr oup ed within ANSY S using no de and elemen t selec tion. For v olume meshes , the filt er reads a 2D or 3D mesh tha t has its b oundar y no des gr oup ed within ANSY S using no de and elemen t selec tion. All boundar y zones will b e consider ed w all z ones; you c an set the appr opriate boundar y types in the meshing mo de or in the solution mo de in F luen t. See Meshes from Third-Party CAD P ackages (p.505) for details . A.3.3.1. Recogniz ed D atasets The f ollowing da tasets ar e recogniz ed b y the gr id filt er: NBL OCK node blo ck da ta EBL OCK elemen t blo ck da ta CMBL OCK elemen t/no de gr ouping The elemen ts must b e STIF63 linear shell elemen ts. In addition, if elemen t da ta without an e xplicit elemen t ID is used , the filt er assumes sequen tial numb ering of the elemen ts when cr eating the z ones . A.3.3.2. Perio dic B oundaries In gener al, it is difficult t o gener ate a v alid gr id with p eriodic b oundar ies in ANSY S. However, a sp ecial feature exists in the meshing mo de in F luen t tha t enables y ou t o gener ate a gr id in a domain with periodic b oundar ies. See Creating P eriodic B oundar ies (p.320) for fur ther details . A.3.4. ARIES F iles ARIES pr ovides a filt er or y ou ma y wr ite a P rep7 file fr om ARIES and use the fe2ram filter with ar gu- men ts for an ANSY S file . For mor e inf ormation on imp orting ANSY S files , see ANSY S Files (p.509). In gener al, to wr ite a P rep7 file within ARIES the f ollowing cr iteria must b e met: •Name the par t in the G eom mo dule . •Create a ma terial or r ead one fr om the ma t_lib in the M aterial mo dule .To create a ma terial, you must supply densit y, Poisson ’s ratio, and elastic mo dulus . •Gener ate fac e pr essur es for the sur face in the En vironmen t mo dule . Later, when y ou wr ite the P rep7 file , these will b e transf erred t o the individual elemen ts. •Gener ate at least one r estraint in the En vironmen t mo dule . 509Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Meshes fr om Third-Party CAD P ackages•Set the elemen t type to be STIF63 (tr iangular shell elemen ts) and sp ecify some finit e thick ness . •Write the P rep7 file , mak ing sur e you let it aut oma tically assign the pr essur e to the elemen ts. You c an filt er the P rep7 file b y using the ARIES or F luen t filt er, whiche ver y ou find most c onvenien t. A.3.5. NASTR AN F iles For NASTR AN sur face meshes , the filt er reads tr iangular and quadr ilateral linear elemen ts tha t define the b oundar ies of the solution domain. For v olume meshes , the filt er reads a 2D or 3D mesh. All boundar y zones ar e consider ed w all z ones; you c an set the appr opriate boundar y types in the meshing mode or in the solution mo de in F luen t. For details , see Meshes fr om Third-Party CAD P ackages (p.505). A.3.5.1. Recogniz ed NASTR AN Bulk D ata E ntries The f ollowing NASTR AN bulk en tries ar e recogniz ed b y the gr id filt er: GRID single-pr ecision no de c oordina tes GRID* double-pr ecision no de c oordina tes CBAR line elemen ts CTETR A, CTRIA3 tetrahedr al and tr iangular elemen ts CHEX A, CQUAD4, CPENT A hexahedr al, quadr ilateral, and w edge elemen ts Because F luen t uses linear elemen ts, you should use linear elemen ts in the mesh-gener ation pr ocess. If par abolic elemen ts exist in the da taset , the filt er ignor es the mid-side no des.This assumption is valid if the edges of the elemen t are near linear . However, if this is not the c ase, an inc orrect topology may result fr om this assumption. For e xample , in r egions of high cur vature the par abolic elemen t may look much diff erent than the linear elemen t. A.3.5.2. Perio dic B oundaries In gener al, it is difficult t o gener ate a v alid gr id with p eriodic b oundar ies in NASTR AN. However, a special f eature exists in the meshing mo de in F luen t tha t enables y ou t o gener ate a gr id in a domain with p eriodic b oundar ies. For details , see Creating P eriodic B oundar ies (p.320). A.3.5.3. Deleting D uplic ate Nodes NASTR AN of ten gener ates duplic ate no des in the pr ocess of cr eating tr iangular elemen ts.You must remo ve them b y click ing Merge in the Merge B oundar y Nodes dialo g box (or b y using the /boundary/merge-duplicates text command). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 510Imp orting B oundar y and Volume M eshesAppendix B . Mesh F ile F ormat The c ontent and f ormat of F luen t mesh files is descr ibed in the f ollowing sec tions: B.1. Guidelines B.2. Formatting C onventions in B inar y Files and F ormatted F iles B.3. Grid Sections B.4. Non-G rid Sections B.5. Example F iles Note A mesh file is a subset of a c ase file; it c ontains only those sec tions of the c ase file tha t pertain to the mesh. The cur rently defined sec tions r elevant for the mesh file ar e explained in the following sec tions . For inf ormation ab out sec tions in the c ase file , refer to Grid S ections (p.3970 ) and Other (N on-G rid) C ase S ections (p.3981 ) in the Fluen t User's G uide (p.1). B.1. Guidelines The mesh files ar e br oken in to se veral sec tions acc ording t o the f ollowing guidelines: •Each sec tion is enclosed in par entheses and b egins with a decimal in teger indic ating its t ype.This in teger is diff erent for formatted and binar y files (see Formatting C onventions in B inar y Files and F ormatted Files (p.511)). •All gr oups of it ems ar e enclosed in par entheses .This mak es sk ipping t o ends of (sub)sec tions and parsing them v ery easy . It also allo ws for easy and c ompa tible addition of new it ems in futur e releases . •Header inf ormation f or lists of it ems is enclosed in separ ate sets of par entheses , preceding the it ems , which are in their o wn par entheses . B.2. Formatting C onventions in Binar y Files and F ormatted F iles For formatted files , examples of file sec tions ar e giv en in Grid S ections (p.512) and Non-G rid S ec- tions (p.521). For binar y files , the header indic es descr ibed in subsequen t sec tions (f or e xample ,10 for the no de sec tion) ar e pr eceded b y 20 for single-pr ecision binar y da ta, or b y 30 for double-pr ecision binar y da ta (tha t is,2010 or 3010 inst ead of 10). The end of the binar y da ta is indic ated b y End of Binary Section 2010 or End of Binary Section 3010 before the closing par amet ers of the sec tion. An example with the binar y da ta represen ted b y periods is as f ollows: (3010 (2 1 2aad 2 3)( . . . ) End of Binary Section 3010) 511Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.B.3. Grid S ections Grid sec tions ar e stored in the c ase file . A mesh file is a subset of a c ase file , containing only those sec tions pertaining t o the mesh. The cur rently defined gr id sec tions ar e explained in the f ollowing sec tions . B.3.1. Commen t B.3.2. Header B.3.3. Dimensions B.3.4. Nodes B.3.5. Periodic S hado w Faces B.3.6. Cells B.3.7. Faces B.3.8. Edges B.3.9. Face Tree B.3.10. Cell Tree B.3.11. Interface Face Parents The sec tion ID numb ers ar e indic ated in b oth symb olic and numer ic forms.The symb olic r epresen tations are available as symb ols in a Scheme sour ce file (xfile.scm ), which is a vailable fr om ANSY S, Inc., or as macr os in a C header file ( xfile.h ), which is lo cated in y our installa tion ar ea. B.3.1. Commen t 0 Inde x: xf-comment Scheme symb ol: XF_COMMENT C macr o: optional Status: Commen t sec tions c an app ear an ywher e in the file (e xcept within other sec tions) as: (0 "comment text") You should pr ecede each long sec tion or gr oup of r elated sec tions , by a c ommen t sec tion e xplaining wha t is t o follow. For e xample , (0 "Variables:") (60 ( (max-skew-limit 1.) (max-cell-skew 0.85) (skewness-method 0) )) B.3.2. Header 1 Inde x: xf-header Scheme symb ol: XF_HEADER C macr o: optional Status: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 512Mesh F ile F ormatHeader sec tions c an app ear an ywher e in the file (e xcept within other sec tions). The f ollowing is an example: (1 "ANSYS(R) TGrid(TM) 3D, serial 15.0.0") The pur pose of this sec tion is t o iden tify the pr ogram tha t wr ote the file . Although this sec tion c an app ear an ywher e, it is t ypic ally one of the first sec tions in the file . Additional header sec tions indic ate other pr ograms tha t ma y ha ve been used in gener ating the file .This pr ovides a hist ory mechanism showing wher e the file c ame fr om and ho w it w as pr ocessed . B.3.3. Dimensions 2 Inde x: xf-dimension Scheme symb ol: XF_DIMENSION C macr o: optional Status: The dimensions of the gr id app ear as: (2 ND) wher e ND is 2 or 3. This sec tion is supp orted as a check tha t the gr id has the appr opriate dimensions . B.3.4. Nodes 10 Inde x: xf-node Scheme symb ol: XF_NODE C macr o: requir ed Status: The no des sec tion app ears as: (10 (zone-id first-index last-index type ND)( x1 y1 z1 x2 y2 z2 . . . )) •If zone-id is zero, this pr ovides the t otal numb er of no des in the mesh. In this c ase,first-index will be one ,last-index will b e the t otal numb er of no des in he xadecimal ,type is zero,ND is omitt ed, and ther e are no c oordina tes following (the par entheses f or the c oordina tes ar e omitt ed as w ell). For e xample , (10 (0 1 2d5 0)) •If zone-id is gr eater than z ero, it indic ates the z one t o which the no des b elong . In this c ase,first- index and last-index are the indic es of the no des in the z one in he xadecimal .The v alues of last- index in each z one must b e less than or equal t o the v alue in the declar ation sec tion.type indic ates the type of no des in the z one .The following v alues ar e used t o indic ate the no de t ype: 513Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Grid Sections–Zero for “virtual” nodes. –One f or no (an y) type. –Two for b oundar y no des. Nodes of t ype zero ar e ignor ed but t ypes one and t wo ar e read and wr itten. ND is an optional ar gumen t tha t indic ates the dimensionalit y of the no de da ta, wher e ND is 2 or 3. If the numb er of dimensions in the gr id is t wo, as sp ecified in the Dimensions (p.513) or in the no de header , then only x and y c oordina tes ar e pr esen t on each line . The f ollowing is an e xample of a t wo-dimensional gr id: (10 (1 1 2d5 1 2)( 1.500000e-01 2.500000e-02 1.625000e-01 1.250000e-02 . . . 1.750000e-01 0.000000e+00 2.000000e-01 2.500000e-02 1.875000e-01 1.250000e-02 )) As the gr id connec tivit y is c omp osed of in tegers r epresen ting p ointers (see Cells (p.515) and Faces (p.516)), using he xadecimal c onser ves spac e in the file and pr ovides f or fast er file input and output. The header indic es ar e also in he xadecimal so tha t the y ma tch the indic es in the b odies of the grid connec tivit y sec tions .The zone-id and type are also in he xadecimal f or c onsist ency. B.3.5. Periodic S hado w Faces 18 Inde x: xf-periodic-face Scheme symb ol: XF_PERIODIC_FACE C macr o: requir ed only f or gr ids with p eriodic boundar iesStatus: This sec tion indic ates the pair ings of p eriodic fac es on p eriodic b oundar ies. Grids without p eriodic boundar ies do not ha ve sec tions of this t ype. The f ormat of the sec tion is as f ollows: (18 (first-index last-index periodic-zone shadow-zone)( f00 f01 f10 f11 f20 f21 . . . )) wher e: •first-index is the inde x of the first p eriodic fac e pair in the list. •last-index is the inde x of the last p eriodic fac e pair in the list. •periodic-zone is the z one ID of the p eriodic fac e zone . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 514Mesh F ile F ormat•shadow-zone is the z one ID of the c orresponding shado w fac e zone . These ar e in he xadecimal f ormat. The indic es in the sec tion b ody (f*) refer to the fac es on each of the p eriodic b oundar ies (in he xa- decimal), the indic es b eing off sets in to the list of fac es for the gr id. Note The first-index and last-index do not refer to fac e indic es; the y refer to indic es in the list of p eriodic pairs . An example of such a sec tion is as f ollows: (18 (1 2b a c) ( 12 1f 13 21 ad 1c2 . . . )) B.3.6. Cells 12 Inde x: xf-cell Scheme symb ol: XF_CELL C macr o: requir ed Status: The declar ation sec tion f or c ells is similar t o tha t for no des. (12 (zone-id first-index last-index type element-type)) When zone-id is z ero, it indic ates tha t it is a declar ation of the t otal numb er of c ells. If last-index is zero, then ther e ar e no c ells in the gr id.This is useful when the file c ontains only a sur face mesh as it ser ves to aler t Fluen t tha t it c annot b e used in the solv er. In a declar ation sec tion, the type has a v alue of z ero, while the element-type is not pr esen t. For e xample , (12 (0 1 3e3 0)) states tha t ther e ar e 3e3 (he xadecimal) = 995 c ells in the gr id.This declar ation sec tion is r equir ed and must pr ecede the r egular c ell sec tions . The element-type in a r egular c ell sec tion header indic ates the t ype of c ells in the sec tion, as f ollows: faces/c ell nodes/c ell descr iption elemen t-type mixed 0 3 3 triangular 1 515Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Grid Sectionsfaces/c ell nodes/c ell descr iption elemen t-type 4 4 tetrahedr al 2 4 4 quadr ilateral 3 6 8 hexahedr al 4 5 5 pyramid 5 5 6 wedge 6 NF NN polyhedr al 7 wher e NN and NF will v ary, dep ending on the sp ecific p olyhedr al cell. Regular c ell sec tions ha ve no b ody, but the y ha ve a header of the same f ormat wher e first-index and last-index indic ate the r ange f or the par ticular z one ,type indic ates whether the c ell z one is fluid (type = 1) or solid ( type = 17). A type of z ero indic ates a dead z one and will b e sk ipped when the file is r ead in solution mo de in Fluen t. If a z one is of mix ed t ype (element-type =0), it will ha ve a b ody tha t lists the element- type of each c ell. In the f ollowing e xample , ther e ar e 3d (he xadecimal) = 61 c ells in c ell z one 9, of which the first 3 ar e triangles , the ne xt 2 ar e quadr ilaterals, and so on. (12 (9 1 3d 0 0)( 1 1 1 3 3 1 1 3 1 . . . )) Note The c ell sec tion is not r equir ed in meshing mo de when the file c ontains only a sur face mesh. B.3.7. Faces 13 Inde x: xf-face Scheme symb ol: XF_FACE C macr o: requir ed Status: The fac e sec tion has a header with the same f ormat as tha t for c ells, but with a sec tion inde x of 13. The f ormat is as f ollows: (13 (zone-id first-index last-index bc-type face-type)) wher e: •zone-id = zone ID of the fac e sec tion •first-index = inde x of the first fac e in the list •last-index = inde x of the last fac e in the list •bc-type = ID of the b oundar y condition r epresen ted b y the fac e sec tion Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 516Mesh F ile F ormat•face-type = ID of the t ype(s) of fac e(s) in the sec tion A zone-id of z ero indic ates a declar ation sec tion, which pr ovides a c oun t of the t otal numb er of faces in the mesh. Such a sec tion omits the bc-type and is not f ollowed b y a b ody with fur ther in- formation. A non-z ero zone-id indic ates a r egular fac e sec tion and will b e followed b y a b ody containing in- formation ab out the gr id connec tivit y. Each line descr ibes one fac e and app ears as f ollows: n0 n1 n2 c0 c1 wher e n* are the defining no des (v ertices) of the fac e, and c* are the adjac ent cells. This is an e xample of the f ormat for a 3D gr id with a tr iangular fac e format.The ac tual numb er of nodes dep ends on the face-type .The or der of the c ell indic es is imp ortant and is det ermined b y the r ight-hand r ule: if y ou cur l the fingers of y our r ight hand in the or der of the no des, your thumb will p oint toward c0. If the fac e zone is of mix ed t ype (fac e-type= 0) or of p olygonal t ype (fac e-type= 5), each line of the section b ody will b egin with a r eference to the numb er of no des tha t mak e up tha t par ticular fac e, and has the f ollowing f ormat: x n0 n1 ... nf c0 c1 wher e x = numb er of no des (v ertices) of the fac e and nf is the final no de of the fac e. All cells, faces, and no des ha ve positiv e indic es. If a fac e has a c ell only on one side , then either c0 or c1 is z ero. For files c ontaining only a b oundar y mesh, both these v alues ar e zero. bc-type indic ates the ID of the b oundar y condition r epresen ted b y the fac e sec tion. The cur rent valid b oundar y condition t ypes ar e defined in the f ollowing table: Descr iption bc-type interior 2 wall 3 pressur e-inlet , inlet-v ent, intake-fan 4 pressur e-outlet , exhaust-fan, outlet-v ent 5 symmetr y 7 periodic-shado w 8 pressur e-far-field 9 velocity-inlet 10 periodic 12 fan, porous-jump , radia tor 14 mass-flo w-inlet 20 interface 24 parent (hanging no de) 31 outflo w 36 axis 37 517Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Grid SectionsThe fac es resulting fr om the in tersec tion of the non-c onformal gr ids ar e plac ed in a separ ate fac e zone . A fac tor of 1000 is added t o the bc-type of these sec tions; for e xample , 1003 is a w all z one . face-type indic ates the t ype of fac es in the z one as defined in the f ollowing table: nodes/fac e descr iption face-type mixed 0 2 linear 2 3 triangular 3 4 quadr ilateral 4 NN polygonal 5 wher e NN will v ary, dep ending on the sp ecific p olygonal fac e. B.3.8. Edges 11 Inde x: xf-edge Scheme symb ol: XF_EDGE C macr o: optional Status: The edge sec tion has a header of the f ollowing f ormat: (11 (zone-id first-index last-index type element-type)) wher e: •zone-id is the z one ID f or the edge sec tion •first-index and last-index are the inde x of the first and last edge in the list , respectively •type indic ates the edge t ype •The element-type is ignor ed c omplet ely. A zone-id of z ero indic ates a declar ation sec tion with no b ody, which pr ovides a c oun t of the t otal numb er of edges in the mesh. A non-z ero zone-id indic ates a r egular edge sec tion, and will b e fol- lowed b y a b ody containing inf ormation ab out the gr id connec tivit y. Each line descr ibes one edge and app ears as f ollows: v0 v1 wher e v0,v1 are the v ertices defining the edge . type denot es the edge t ype as defined in the f ollowing table: type Descr iption 5 boundar y edge Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 518Mesh F ile F ormattype Descr iption 6 interior edge Note In case files wr itten f or F luen t, the E dges sec tion will b e omitt ed. B.3.9. Face Tree 59 Inde x: xf-face-tree Scheme symb ol: XF_FACE_TREE C macr o: only f or gr ids with hanging-no de adaptionStatus: This sec tion indic ates the fac e hier archy of the gr id containing hanging no des.The f ormat of the sec tion is as f ollows: (59 (face-id0 face-id1 parent-zone-id child-zone-id) ( number-of-kids kid-id-0 kid-id-1 ... kid-id-n . . . )) wher e face-id0 is the inde x of the first par ent fac e in the sec tion. face-id1 is the inde x of the last par ent fac e in the sec tion. parent-zone-id is the ID of the z one c ontaining the par ent fac es child-zone-id is the ID of the z one c ontaining the childr en fac es. number-of-kids is the numb er of childr en of the par ent fac e. kid-id-n are the fac e IDs of the childr en. These ar e in he xadecimal f ormat.You c an r ead files tha t contain this sec tion in the meshing mo de in Fluen t. B.3.10. Cell Tree 58 Inde x: xf-cell-tree Scheme symb ol: XF_CELL_TREE C macr o: only f or gr ids with hanging-no de adaptionStatus: 519Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Grid SectionsThis sec tion indic ates the c ell hier archy of the gr id containing hanging no des. The f ormat of the sec tion is as f ollows: (58 (cell-id0 cell-id1 parent-zone-id child-zone-id) ( number-of-kids kid-id-0 kid-id-1 ... kid-id-n . . . )) wher e: •cell-id0 is the inde x of the first par ent cell in the sec tion. •cell-id1 is the inde x of the last par ent cell in the sec tion. •parent-zone-id is the ID of the z one c ontaining the par ent cells. •child-zone-id is the ID of the z one c ontaining the childr en c ells. •number-of-kids is the numb er of childr en of the par ent cell. •kid-id-n are the c ell IDs of the childr en. These ar e in he xadecimal f ormat.You c annot r ead files tha t contain this sec tion in the meshing mo de in Fluen t. B.3.11. Interface Face Parents 61 Inde x: xf-face-parents Scheme symb ol: XF_FACE_PARENTS C macr o: only f or gr ids with non-c onformal interfacesStatus: This sec tion indic ates the r elationship b etween the in tersec tion fac es and or iginal fac es.The in tersec tion faces (childr en) ar e pr oduced fr om in tersec ting t wo non-c onformal sur faces (par ents) and ar e some fraction of the or iginal fac e. Each child will r efer to at least one par ent. The f ormat of the sec tion is as f ollows: (61 (face-id0 face-id1) ( parent-id-0 parent-id-1 . . . )) wher e: •face-id0 is the inde x of the first child fac e in the sec tion. •face-id1 is the inde x of the last child fac e in the sec tion. •parent-id-* is the inde x of the par ent fac es. These ar e in he xadecimal f ormat. If you set up and sa ve a non-c onformal mesh in the solution mo de and then r ead it in to the meshing mode of F luen t, this sec tion will b e sk ipped. Hence, all the inf ormation nec essar y to pr eser ve the non- Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 520Mesh F ile F ormatconformal in terface will not b e main tained .When y ou swit ch t o the solution mo de or r ead the mesh back in to the solution mo de, you will need t o recreate the in terface. B.4. Non-G rid S ections The non-gr id sec tions c ontain the b oundar y conditions , ma terial pr operties, and solv er control settings . B.4.1. Zone B.4.1. Zone 39 or 45 Inde x: xf-rp-tv Scheme symb ol: XF_RP_TV C macr o: requir ed Status: Typic ally, ther e is one z one sec tion f or each z one r eferenced b y the gr id. Although some gr id zones may not ha ve corresponding sec tions , ther e cannot b e mor e than one z one sec tion f or each z one . The z one sec tion has the f ollowing f orm: (39 (zone-id zone-type zone-name domain-id)( (condition1 . value1) (condition2 . value2) (condition3 . value3) . . . )) Grid gener ators and pr eprocessors need only pr ovide the sec tion header and lea ve the list of c onditions empt y, as in: (39 (zone-id zone-type zone-name domain-id)()) The empt y par entheses a t the end ar e requir ed.The solv er adds c onditions as appr opriate, dep ending on the z one t ype. When only zone-id ,zone-type ,zone-name , and domain-id are sp ecified , the inde x 45 ma y be used f or a z one sec tion. However, the inde x 39 must b e used if b oundar y conditions ar e pr esen t, because an y and all r emaining inf ormation in a sec tion of inde x 45 af ter zone-id ,zone-type , zone-name , and domain-id will b e ignor ed. In meshing mo de, the z one name and t ype can b e extracted fr om the b oundar y condition sec tion 39 (refer to the F luen t User’s Guide f or details) or 45, but only sec tion 39 can b e wr itten. The zone-id is in decimal f ormat.This is in c ontrast t o the use of he xadecimal in the gr id sec tions . The zone-type is one of the f ollowing: degassing exhaust-fan fan fluid geometry inlet-vent 521Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Non-G rid Sectionsintake-fan interface interior internal mass-flow-inlet outflow outlet-vent parent-face porous-jump pressure-far-field pressure-inlet pressure-outlet radiator solid symmetry velocity-inlet wall wrapper The interior ,fan ,porous-jump , and radiator types c an b e assigned only t o zones of fac es inside the domain. The interior type is used f or the fac es within a c ell z one; the others ar e for in- terior fac es tha t form infinit ely thin sur faces within the domain. Fluen t allo ws the wall type to be assigned t o fac e zones b oth on the inside and on the b oundar ies of the domain. Some z one t ypes ar e valid only f or c ertain t ypes of gr id comp onen ts (f or e xample , cell z ones c an b e assigned only either fluid or solid type). All other t ypes list ed c an b e used f or only b oundar y (fac e) zones . The zone-name is a lab el for the z one . It must b e a v alid Scheme symb ol and is wr itten without quot es.The r ules f or a v alid zone-name are as f ollows: •The first char acter must b e a lo wercase lett er or a sp ecial-initial. •Each subsequen t char acter must b e a lo wercase lett er, a sp ecial-initial, a digit , or a sp ecial-subsequen t. A sp ecial-initial char acter is one of the f ollowing: ! $ % & * / : < = > ? ~ _ ^ and a sp ecial subsequen t is one of the f ollowing: . + - Some e xamples of z one sec tions pr oduced in the meshing mo de ar e as f ollows: (39 (1 fluid fuel 1)()) (39 (8 pressure-inlet pressure-inlet-8 2)()) (39 (2 wall wing-skin 3)()) (39 (3 symmetry mid-plane 1)()) B.5. Example F iles The e xamples sho w 2D quadr ilateral meshes f or easier illustr ation. The same c onc epts ar e applied t o 3D meshes . Example 1 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 522Mesh F ile F ormatFigur e 1: Quadr ilateral M esh (p.523) illustr ates a simple quadr ilateral mesh with no p eriodic b oundar ies or hanging no des. Figur e 1: Quadr ilateral M esh The f ollowing descr ibes this mesh: (0 "Grid:") (0 "Dimensions:") (2 2) (12 (0 1 3 0)) (13 (0 1 a 0)) (10 (0 1 8 0 2)) (12 (7 1 3 1 3)) (13 (2 1 2 2 2)( 1 2 1 2 3 4 2 3)) (13 (3 3 5 3 2)( 5 1 1 0 1 3 2 0 3 6 3 0)) (13 (4 6 8 3 2)( 7 4 3 0 4 2 2 0 2 8 1 0)) (13 (5 9 9 a 2)( 8 5 1 0)) (13 (6 a a 24 2)( 6 7 3 0)) (10 (1 1 8 1 2) ( 1.00000000e+00 0.00000000e+00 1.00000000e+00 1.00000000e+00 2.00000000e+00 0.00000000e+00 2.00000000e+00 1.00000000e+00 0.00000000e+00 0.00000000e+00 3.00000000e+00 0.00000000e+00 3.00000000e+00 1.00000000e+00 0.00000000e+00 1.00000000e+00)) Example 2 Figur e 2: Quadr ilateral M esh with P eriodic B oundar ies (p.524) illustr ates a simple quadr ilateral mesh with periodic b oundar ies but no hanging no des. In this e xample ,bf9 and bf10 are fac es on the p eriodic zones . 523Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Example F ilesFigur e 2: Quadr ilateral M esh with P eriodic B oundar ies The f ollowing descr ibes this mesh: (0 "Dimensions:") (2 2) (0 "Grid:") (12 (0 1 3 0)) (13 (0 1 a 0)) (10 (0 1 8 0 2)) (12 (7 1 3 1 3)) (13 (2 1 2 2 2)( 1 2 1 2 3 4 2 3)) (13 (3 3 5 3 2)( 5 1 1 0 1 3 2 0 3 6 3 0)) (13 (4 6 8 3 2)( 7 4 3 0 4 2 2 0 2 8 1 0)) (13 (5 9 9 c 2)( 8 5 1 0)) (13 (1 a a 8 2)( 6 7 3 0)) (18 (1 1 5 1)( 9 a)) (10 (1 1 8 1 2)( 1.00000000e+00 0.00000000e+00 1.00000000e+00 1.00000000e+00 2.00000000e+00 0.00000000e+00 2.00000000e+00 1.00000000e+00 0.00000000e+00 0.00000000e+00 3.00000000e+00 0.00000000e+00 3.00000000e+00 1.00000000e+00 0.00000000e+00 1.00000000e+00)) Example 3 Figur e 3: Quadr ilateral M esh with Hanging N odes (p.525) illustr ates a simple quadr ilateral mesh with hanging no des. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 524Mesh F ile F ormatFigur e 3: Quadr ilateral M esh with H anging N odes The f ollowing descr ibes this mesh: (0 "Grid:") (0 "Dimensions:") (2 2) (12 (0 1 7 0)) (13 (0 1 16 0)) (10 (0 1 d 0 2)) (12 (7 1 6 1 3)) (12 (1 7 7 20 3)) (58 (7 7 1 7)( 4 6 5 4 3)) (13 (2 1 7 2 2)( 1 2 6 3 1 3 3 4 1 4 4 5 1 5 5 6 6 7 1 2 5 8 2 6 9 5 2 5)) (13 (3 8 b 3 2)( a 6 1 0 6 9 2 0 4 b 4 0 9 4 5 0)) (13 (4 c f 3 2)( 2 8 6 0 c 2 3 0 8 7 2 0 7 d 1 0)) (13 (5 10 10 a 2)( d a 1 0)) (13 (6 11 12 24 2)( 3 c 3 0 b 3 4 0)) (13 (b 13 13 1f 2)( c 8 7 0)) (13 (a 14 14 1f 2)( b c 7 0)) (13 (9 15 15 1f 2)( 9 b 7 0)) (13 (8 16 16 1f 2)( 9 8 2 7)) (59 (13 13 b 4)( 2 d c)) 525Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Example F iles (59 (14 14 a 6)( 2 12 11)) (59 (15 15 9 3)( 2 b a)) (59 (16 16 8 2)( 2 7 6)) (10 (1 1 d 1 2) ( 2.50000000e+00 5.00000000e-01 2.50000000e+00 1.00000000e+00 3.00000000e+00 5.00000000e-01 2.50000000e+00 0.00000000e+00 2.00000000e+00 5.00000000e-01 1.00000000e+00 0.00000000e+00 1.00000000e+00 1.00000000e+00 2.00000000e+00 1.00000000e+00 2.00000000e+00 0.00000000e+00 0.00000000e+00 0.00000000e+00 3.00000000e+00 0.00000000e+00 3.00000000e+00 1.00000000e+00 0.00000000e+00 1.00000000e+00)) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 526Mesh F ile F ormatAppendix C. Shor tcut K eys Creating a mesh and mo difying or r epair ing it in volves man y op erations .Various t ools ar e available f or mak ing b oundar y repairs , enabling y ou t o perform pr imitiv e op erations on the b oundar y mesh, such as cr eating and deleting no des/fac es; mo ving no des; swapping edges; mer ging/smo othing no des; col- lapsing no des, edges , and fac es; and so on. You c an p erform these op erations using the appr opriate dialo g boxes. However, if y ou ar e handling a large and c omplic ated mesh, you ma y find it difficult t o perform these op erations r epetitiv ely using the dialo g boxes.To mak e your task easy , keyboard shor tcuts ar e available . C.1. Shortcut Ke y Actions Imp ortant To mak e use of the k eyboard shor tcuts , displa y the geometr y in the gr aphics windo w, click in the gr aphics windo w, then pr ess the k ey combina tion. Many of the k eyboard shor tcuts are available as an onscr een t ool butt on along the lef t side and b ottom of the gr aphics windo w. To repeat the same shor tcut multiple times , after pr essing the k ey combina tion, press Ctrl while using the r ight mouse butt on f or multiple selec tions .This r epeat shor tcut is a vailable only f or some op erations .The hot k ey help indic ates the (pr evious) op eration tha t will b e performed in c ase of multiple selec tions . C.1. Shor tcut K ey Actions Onscr een Tool Keys Action Feature Ctrl+H Print the a vailable hot k eys in the message and graphics windo w.Hot k ey list Ctrl+B CAD objec t filt er Selec tion filtersCAD En tities Note Some Keys Ctrl+Z CAD z one filt er Ctrl+X Position filt er and Onscr eenF6 Highligh t par ent CAD objec t Displa y optionsTools may F7 Highligh t child C AD objec t Ctrl+Shift+C Color b y lab els have differentCtrl+Shift+D Color b y thr eadsbehavior Ctrl+C Isola te similar cur vature Isola te tools for CAD 527Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Onscr een Tool Keys Action Feature Assemblies and Ctrl+L Isola te smaller ar ea Ctrl+S Isola te similar ar ea Geometr y/M esh Objec ts. Ctrl+G Delete inac tive/suppr essed C AD objec tsTree options Ctrl+Y Clear C AD tr ee selec tions Ctrl+Shift+P Show C AD objec t pa th Ctrl+P Add t o objec t Objec t managemen t Ctrl+Q Replac e objec t Ctrl+Shift+B Create objec ts Ctrl+Shift+L Manage lab els Label managemen t Ctrl+I CAD z one asso ciated lab els Ctrl+Shift+F Extract edge z ones Modify Ctrl+Shift+N Rename C AD objec ts Ctrl+Shift+R Update CAD objec ts Ctrl+Shift+S Suppr ess C AD objec ts Ctrl+J Restore delet ed no des Up ar row Increase Displa y boundsDown ar- rowDecrease Ctrl+L Prints the c oordina tes of the c entroid of the selec ted fac e to the c onsole . This also w orks for edges and no des.Faces Ctrl+O Rezones the selec ted fac es/c ells t o the tar get z one . Apply af ter setting a tar get z one and selec ting sour ce fac e(s) or c ell(s). Ctrl+Shift+J Mark fac es based on selec tions and sp ecified paramet ers. Marking fac es allo ws for selec tive separ ation or r emeshing . If help t ext displa y is ac tive, a descr iption of the mar king options is displa yed. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 528Shortcut Ke ysOnscr een Tool Keys Action Feature Ctrl+S Mark selec ted fac es. Marking optionsCtrl+D Mark fac es b y flo od filling . Ctrl+R Mark fac es in r ings ar ound selec tion. Ctrl+Q Mark fac es b y qualit y. Ctrl+G Mark fac es b y angle . Ctrl+L Mark island fac es. Ctrl+U Unmar k all/selec ted mar ked fac es Ctrl+I Opens the Mark Settings dialo g box, wher e you c an set the paramet ers f or mar king fac es. Ctrl+Shift+R Open the Local Remesh or Zone Remesh dialo g box to set options and r emesh fac es (or z ones) based on y our selec tion in the gr aphics windo w. •Face selec tion will r emesh the fac e and sp ecified radial la yers based on settings in the Local Remesh dialo g box. •Face zone selec tion will r emesh the z one based on settings in the Zone Remesh dialo g box. •No selec tion will r emesh mar ked fac es. Ctrl+Shift+S Separ ates the fac e or edge z ones based on the selec ted en tity. •If a multi-r egion fac e zone is selec ted, then the face zones ar e separ ated b y region. •If a single r egion fac e zone is selec ted, then the face zones ar e separ ated b y angle . •If a fac e (or edge) is selec ted, then the fac e zone (edge z one) is separ ated b y seed . •If edge z one with fac e seed selec tion, then the face zone is separ ated b y edge lo op. •If no selec tion, then the fac e zones ar e separ ated by mar k. Opens the C reate Edge Z ones dialo g box to extract the edges of the sur face(s) c ontaining the selec ted face(s). See Extract Edge Z ones (p.327). Ctrl+Shift+E Show/hide edges on selec ted z ones and objec ts indep enden t of the mo de of selec tion.I f noEdges objec t/zone is selec ted, then the edges on the entire geometr y are sho wn/hidden. Ctrl+L Prints the c oordina tes of the c enter of the selec ted edge t o the c onsole . This also w orks for fac es and no des. 529Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Shortcut Ke y ActionsOnscr een Tool Keys Action Feature Right ar- rowDispla y in decr easing or der of sk ewness in the mesh/ac tive gr oup or the mar ked fac es.Skewed fac es Left ar row Clear F3 Toggle b etween the mouse-dolly and the option currently selec ted f or the r ight-mouse butt on.Mouse But- tons dialo g box or orF4 Toggle the selec tion of the mouse pr obe func tion between polygon and the option cur rently selec ted in the Mouse P robe dialo g box. Note When using box selec t or polygon selec t, by default , all en titiesMouse P robe (nodes, faces, zones , objec ts) will be selec ted. To selec t only visible en tities instead, enable Selec t Visible E n- tities in the Mouse P robe Func- tions group in the r ibbon. •If the mesh is not c onnec ted, all entities (no des, faces, zones , objec ts) will b e selec ted ir respective of whether the y are visible or not. •This visual selec tion b ehavior w orks only on lo cal displa ys and ma y gener ate warning messages when attempting selec tion on a r emot e system. Ctrl+B Selec t objec t as the selec tion filt er. Ctrl+C Selec t cell as the selec tion filt er. This w orks only in the Linux v ersion. Ctrl+E Selec t edge as the selec tion filt er. Ctrl+F Selec t face as the selec tion filt er. Ctrl+N Selec t node as the selec tion filt er. Ctrl+X Selec t position as the selec tion filt er. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 530Shortcut Ke ysOnscr een Tool Keys Action Feature Ctrl+Y Selec t size based on the c omput ed siz e field as the selec tion filt er. Ctrl+Z Selec t zone as the selec tion filt er. F5 Create the selec ted en tity. Entities F6 Smooth the selec ted en tity. F7 Perform the split op eration on the selec ted en tity (only fac e and edge). F8 Perform the sw ap op eration on the selec ted en tity (only fac e and edge). F9 Merge the selec ted pair . Ctrl+J Alternatively, Ctrl+^Perform the c ollapse op eration on the selec ted nodes, edges , or fac es. Ctrl+W Delete the selec ted en tities (nodes/fac es/z ones/objec ts) without c onfir ming . Ctrl+Shift+Z Toggle E dge Z one selec tion mo de.This r estricts selec tion t o edge z ones en tities only . Ctrl+Shift+H Hide the selec ted objec ts or z ones in the displa y dep ending on the mode of selec tion set.Viewing options only .These do not Ctrl+Shift+I Isola te selec ted z ones/objec ts. affect the mesh. Ctrl+Shift+U Reverse the last sho w/hide operation. Ctrl+I Print detailed inf ormation about the selec ted en tities in the message windo w. For mor e details , see Entity Information (p.537). In addition, if a selec ted z one or objec t has b een set as a target, this hotk ey, or t ool butt on, will t oggle the iden tifying c olor . Ctrl+[ Alternatively: EscDeselec t the last selec ted en tity. 531Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Shortcut Ke y ActionsOnscr een Tool Keys Action Feature F2 Clear all selec tion and visualiza tion assists . Ctrl+Shift+A Show all hidden z ones/objec ts; show pr eviously hidden zones/objec ts. Ctrl+D Calcula te and displa y the distanc e between the t wo selec ted en tities . The v alue is also pr inted in the console windo w. Ctrl+G Displa ys the neighb oring fac e zones of the selec ted en tity. Ctrl+V Move no des fr om their or iginal lo cation t o a new position.Nodes Ctrl+L Prints the c oordina tes of the selec ted no de t o the console . F11 Show only the w orst sk ewed fac e and its ID; print the sk ewness v alue in the c onsole .Mesh/ac tive group F12 Undo la test op eration (if p ossible). Mesh operation Ctrl+A Adjust t o fit in the gr aphics windo w. Mesh displa y Ctrl+K Remo ve Boundar y Gaps. Apply af ter setting a target z one and selec ting a sour ce zone .Objec ts Ctrl+Shift+M Merge all the selec ted objec ts/zones in to one objec t/zone dep ending on which mo de of selec tion is set. •For objec t selec tion, only objec ts of the same type (geometr y or mesh) c an b e mer ged . Enter a name f or the mer ged objec t in the Merge O b- jects dialo g box. •For zone selec tion, only z ones of the same t ype or b elonging t o the same objec t can b e mer ged . The r esulting z one inher its the name of the z one selec ted first. Ctrl+Shift+N Open the Change O bjec t Properties or Change Zone P roperties dialo g box, dep ending on y our selec tion. Ctrl+Shift+O Randomly allo cates c olors t o selec ted objec ts/zones , or, if no objec t/zone is selec ted, to the en tire geometr y. Expands the on-scr een selec tion tools menu .Selec tion ToolsGraphics windo w Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 532Shortcut Ke ysOnscr een Tool Keys Action Feature Selec ts the objec t at the mouse pointer. Click and dr ag t o selec t objec ts within a r ectangular b ox. Click r epeatedly t o define an objec t selec tion p olygon. Ctrl+Shift+V Selec ts all the visible objec ts/zones in the gr aphics windo w. Ctrl+_ Displa y the pr evious view . Ctrl+[ Alternatively: EscDeselec t the last selec ted en tity. Ctrl+Shift+G Align objec ts. Ctrl+Shift+A Show all hidden z ones/objec ts; show pr eviously hidden zones/objec ts.Visualiza tion Tools Ctrl+Shift+H Hide the selec ted objec ts or z ones in the displa y dep ending on the mode of selec tion set. Ctrl+Shift+I Isola te selec ted z ones/objec ts. Ctrl+Shift+U Reverse the last sho w/hide operation. Expands the on-scr een Viewing tools menu Ctrl+Shift+X Toggle b etween a nor mal view and an e xplo ded view of the objec ts in the geometr y. Ctrl+Shift+T Toggle the tr anspar ency of the selec ted objec ts/zones dep ending on the mo de of selec tion set. If no objec t/zone is selec ted then the entire geometr y is made tr anspar ent so tha t internal objec ts/zones ar e visible . Displa ys objec ts with similar curvature as the cur rent selec tion. Ctrl+D Calcula te and displa y the distanc e between the t wo selec ted en tities . The v alue is also pr inted in the c onsole windo w. 533Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Shortcut Ke y ActionsOnscr een Tool Keys Action Feature Preview siz e field a t selec ted location. Displa ys objec ts with similar ar ea as the cur rent selec tion. Displa ys objec ts with smaller ar ea than the cur rent selec tion. Ctrl+S Set/U nset a pr ojec tion tar get. The tar get will be a line , plane , zone , or objec t dep ending on the selec tion.Projec tion The tar get is used f or easy objec t mo dific ation, for rezoning of fac es/c ells, for pr ojec ting nodes or z ones , or f or gap r emo val. If help t ext displa y is ac tive, a descr iption of the tar get options is displa yed. Ctrl+P Projec t selec ted no des/no de lo ops/z ones on to wha t you ha ve set using Ctrl+S. Ctrl+I Displa ys inf ormation ab out the selec ted tar get and toggles the iden tifying tar get c olor . Ctrl+R Auto pa tch z ones b y filling all holes based on the selec ted en tity. Selec t the fac e zone t o patch all holes asso ciated with fr ee fac es.Zones Selec t individual fac es adjac ent to the hole in the fac e zone t o pa tch punched holes . See the User's G uide (p.245) for details . Ctrl+Shift+N Open the Change O bjec t Properties or Change Z one P roperties dialo g box, dep ending on the selec tion of objec ts or zones in the gr aphics windo w. Ctrl+Shift+R If zones ar e gr aphic ally selec ted, the y are remeshed using the siz e field , if a vailable . Ctrl+Shift+Y Transf er the selec ted z one(s) t o the tar get objec t, if applied af ter setting a tar get objec t and selec ting sour ce zone(s). If no tar get is set , the selec ted zone(s) will f orm a new geometr y objec t as specified in the Create Geometr y O bjec t dialo g box. Opens the C reate Edge Z ones dialo g box to extract edges of the selec ted fac e zone . See Extract Edge Zones (p.327). Ctrl+Shift+K Enter the C onstr uct Geometr y mo de t o cr eate a bounding b ox, cylinder , or fr ustum f or selec ted or all z ones displa yed in the gr aphics windo w.Constr uct geometr y primitiv es Ctrl+B Create a b ounding b ox for selec ted/all displa yed zones . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 534Shortcut Ke ysOnscr een Tool Keys Action Feature Ctrl+C Create a c ylinder based on selec tions or b ounding all displa yed z ones . Ctrl+F Create a fr ustum based on selec tions or b ounding all displa yed z ones . F5 Open the Create O bjec t dialo g box to sp ecify additional settings . Click Create to cr eate the geometr y objec t based on the selec tions and settings . Ctrl+Shift+L Enter the L oop S elec tion M ode. Selec t a lo op of nodes/p ositions f or pr obe selec tion or f or cr eating an edge lo op or c apping sur face.Loop of nodes Selec t position f or lo op cr eation. Selec tion options Ctrl+O Toggle b etween an op en or closed loop. Ctrl+D Toggle b etween using the dir ect or no de lo opClosed lo op options closing pa th between the first and last no des. Ctrl+E Toggle b etween using the dir ect or feature pa th between the first and last no des. Ctrl+B Toggle b etween using the dir ect or z one boundar y pa th between the first and last no des. Ctrl+P Toggle b etween using the no de path or the dir ect pa th b etween the last t wo no des selec ted. Ctrl+F Toggle b etween using the f eature path or the dir ect pa th b etween the last t wo no des selec ted. Ctrl+Z Toggle b etween using the z one boundar y pa th or the dir ect pa th between the last t wo no des selec ted. Ctrl+J Selec t all no des on the lo op pa th. Create options 535Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Shortcut Ke y ActionsOnscr een Tool Keys Action Feature Ctrl+K Create a c apping sur face based on the no des selec ted. Ctrl+L Create an edge lo op based on the nodes selec ted. Ctrl+Shift+B Enter List S elec tion options mo de. List S elec tion Options mode Contains options f or c ontrolling selec tion lists in dialo g boxes based on z ones or objec ts selec ted in the gr aphics windo w.You c an also selec t fac e zone lab els in the tr ee based on zones selec ted in the gr aphics windo w. Ctrl+Q Add the selec ted z ones t o the current selec tions in the dialo g box list.Zone selec tion Ctrl+S Remo ve the selec ted z ones fr om the current selec tions in the dialo g box list. Ctrl+D Set the selec ted z ones as the current selec tions in the dialo g box list. Ctrl+J Add the selec ted objec ts to the current selec tions in the dialo g box list.Objec t selec tion Ctrl+K Remo ve the selec ted objec ts fr om the cur rent selec tions in the dialo g box list. Ctrl+L Set the selec ted objec ts as the current selec tions in the dialo g box list. Ctrl+F Add the fac e zone lab els corresponding t o zones selec ted t o the cur rent selec tions in the tr ee.Face Zone Label selec tion Ctrl+G Remo ve the fac e zone lab els corresponding t o zones selec ted from the cur rent selec tions in the tree. Ctrl+R Set the fac e zone lab els corresponding t o zones selec ted as the cur rent selec tions in the tr ee. F2 Exit list selec tion options mo de. Ctrl+Shift+C Enter the C olor Options mo de. Color Options modeCtrl+G Color the it ems b y geometr y recovery attribut e. Ctrl+O Color the it ems b y objec t. Ctrl+Z Color the it ems b y zone . Ctrl+N Color the it ems based on nor mals . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 536Shortcut Ke ysOnscr een Tool Keys Action Feature Ctrl+P Toggle the c olor palett e. Ctrl+R Randomiz e the c olors used in the displa y. F2 Exit c olor options mo de. Ctrl+Shift+D Enter the C onditional D ispla y Options mo de. Conditional Displa y Ctrl+S Isola te zones/objec ts with similar sur face ar ea t o selec ted.Options mode Ctrl+I Isola te zones/objec ts with sur face ar ea less than or equal t o selec ted. Ctrl+C Isola te zones/objec ts of similar sur face cur vature. Ctrl+N Isola te zones/objec ts with neighb orhood. Ctrl+Shift+A Show all z ones/objec ts in the gr aphics windo w; unhide pr eviously hidden z ones/objec ts. F2 Exit c onditional displa y options mo de. Ctrl+T Enter the M iscellaneous Tools mo de. Miscellaneous Tools mo deCtrl+P Preview siz es on selec ted/all z ones . Ctrl+C Draw siz e contours on selec ted/all z ones . Ctrl+T Trace pa th b etween selec ted en tities . Ctrl+J Join selec ted fac e zones using the options in the Join dialo g box. Ctrl+I Intersec t selec ted fac e zones using the options in the Intersec t dialo g box. Ctrl+Shift+F Enables y ou t o impr ove feature captur e and/or rezone wr ap fac e zones .Wrap fac e zones •When wr ap fac e zones ar e selec ted, the y are rezoned . •When wr ap fac e zones and edge z ones ar e selec ted, feature captur e on the wr ap fac e zones is impr oved and the fac e zones ar e rezoned . •When wr ap fac e zones and edge en tities ar e selec ted, feature captur e on the wr ap fac e zones is impr oved. C.1.1. Entity Inf ormation The inf ormation displa yed f or the selec ted en tities using the hot k ey Ctrl+I is as f ollows: Information displa yed Entity selec ted Zone Zone name Zone ID Location 537Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Shortcut Ke y ActionsInformation displa yed Entity selec ted Zone t ype Objec t tha t the z one is included in Face zone lab els tha t the z one is included in Regions tha t the z one is included in Size func tions Face Face name Zone ID Nodes Adjoining c ell(s) Face sk ewness (if applic able) Periodic t wins (if applic able) Child fac es (if applic able) Edge Edge name Zone ID Adjoining fac es Cell Cell name Zone ID Nodes Faces Cell c enter Cell sk ewness Cell simple x radius Cell siz e Node Node name Zone ID Location Adjoining fac es (if applic able) Adjoining c ells (if applic able) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 538Shortcut Ke ysBiblio graph y Imp ortant Under U.S. and in ternational c opyright law, ANSY S, Inc. is unable t o distr ibut e copies of the pap ers list ed in the biblio graph y, other than those published in ternally b y ANSY S, Inc. Use your libr ary or a do cumen t deliv ery ser vice to obtain c opies of c opyrighted pap ers. [1] T. J. Baker.Three D imensional Mesh G ener ation B y Triangulation of A rbitr ary Point S ets.Technic al R eport AIAA -87-1124 .Amer ican Institut e of A eronautics and A stronautics .1987. [2] T. J. Barth.Three-D imensional Unstr uctured G rid G ener ation via Incr emental Inser tion and L ocal O ptim- ization In S oftware Systems f or S urface Mo deling and G rid G ener ation .Langle y Resear ch C enter, Hampt on,Virginia, NASA C onference Public ation. 3143. April 1992. [3] K. R. Blake.A 3D D elauna y Unstr uctured G rid G ener ator A pplied t o Trains , Planes , and A utomobiles . Technic al R eport AIAA93-0673 .Amer ican Institut e of A eronautics and A stronautics .1993. [4] A. Bowyer.Computing D irichlet Tessellations .The C omput er J ournal .24(2). 162–166. May 1981. [5] M. Garland .Surface Simplific ation U sing Q uadr ic E rror Metr ics.24th A nnual C onferenc e on C omput er Graphics and Int eractive Techniques .209–216. 1997. [6] D. G. Holmes .The G ener ation of Unstr uctured Triangular Meshes U sing D elauna y Triangulation .J. Hauser .Numer ical G rid G ener ation in C omputational F luid Mechanics 88 .643–652. Piner idge P ress Limit ed.1988. [7] Y. Kallinder is.Hybr id P rismatic/T etrahedr al G rid G ener ation f or C omple x Geometr ies Technic al R eport AIAA -95-0211 .AIAA 33r d Aerospac e Scienc es Meeting and E xhibit R eno , Nevada.1995. [8] Y. Kallinder is.Prismatic G rid G ener ation f or Three-D imensional C omple x Geometr ies.AIAA J ournal .31(10). 1850–1856. October 1993. [9] L. Kobb elt. A Shrink Wrapping A ppr oach t o Remeshing P olygonal S urfaces.Comput er G raphics F orum. 18(3). 119–130. 1999. [10] C. L. Lawson. Properties of n-dimensional Triangulations .Comput er-Aided G eometr ic D esign .3. 231–246. Decemb er 1986. [11] R. Löhner .Gener ation of Three-D imensional Unstr uctured G rids b y the A dvancing F ront Metho d Tech- nical R eport, AIAA -88-0515 .Amer ican Institut e of A eronautics and A stronautics .1988. [12] D. J. Mavriplis .Adaptiv e Mesh G ener ation f or Viscous F lows Using D elauna y Triangulation .Journal of Computational P hysics .90(12). 271–291. October 1990. [13] J. D. Müller .A Frontal A ppr oach f or N ode G ener ation in D elauna y Triangulations .International J ournal For N umer ical Metho ds in F luids .17(3). 241–255. August 1993. [14] S. Pirzadeh. Unstr uctured Viscous G rid G ener ation b y the A dvancing-L ayers Metho d.AIAA J ournal .32(8). 1735–1737. August 1994. [15] S. Pirzadeh. Three-D imensional Unstr uctured Viscous G rids b y the A dvancing-L ayers Metho d.AIAA Journal .34(1). 43–49. Januar y 1996. 539Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.[16] W. R. Quadr os.Finite Element Mesh S izing f or S urfaces U sing S kelet on.In P roc 13th Int Meshing Roundtable .2004. [17] J. Z.Wang .An A daptiv e Cartesian G rid G ener ation Metho d for ‘Dirty’ Geometr y.International J ournal For N umer ical Metho ds in F luids .39.703–717. 2002. [18] D. F.Watson. Computing the n-dimensional D elauna y tessellation with applic ation t o Voronoi p olytopes. The C omput er J ournal .24(2). 167–172. May 1981. [19] N. P.Weather ill.A Metho d For G ener ating Irr egular C omputational G rids in Multipl y Connec ted P lanar Domains .International J ournal F or N umer ical Metho ds in F luids .8(2). 181–197 . February 1988. [20] M. A.Yerry.Automatic Three-D imensional Mesh G ener ation b y the Mo dified-O ctree Technique .Interna- tional J ournal f or N umer ical Metho ds in E ngineer ing.20.1965–1990. 1984. [21] J. Zhu .Back ground O verlay Grid S ize Func tions .In P roc 11th Int Meshing R oundtable .2002. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 540Biblio graph yPart III: Solution M ode The sec tion descr ibes ho w to use ANSY S Fluen t in solution mo de. •Using This M anual (p.dxlv ), provides t ypographic al and ma thema tical conventions . •Graphic al U ser In terface (GUI) (p.549), descr ibes the mechanics of using the gr aphic al user in terface and the GUI on-line help . •Text User In terface (TUI) (p.579), descr ibes the mechanics of using the t ext interface and the TUI on-line help . (See the Text Command List f or inf ormation ab out sp ecific t ext interface commands .) •Reading and Writing F iles (p.581), descr ibes the files tha t ANSY S Fluen t can r ead and wr ite, including pic ture files . •Unit S ystems (p.655), descr ibes ho w to use the standar d and cust om unit sy stems a vailable in ANSY S Fluen t. •Fluen t Expr essions Language (p.659), descr ibes ho w to use theANSY S Fluen t Expr ession Language . •Reading and M anipula ting M eshes (p.703), descr ibes the v arious sour ces of c omputa tional meshes and e x- plains ho w to obtain diagnostic inf ormation ab out the mesh and ho w to mo dify it b y scaling , transla ting , and other metho ds.This chapt er also c ontains inf ormation ab out the use of non-c onformal meshes . •Cell Z one and B oundar y Conditions (p.835), descr ibes the diff erent types of b oundar y conditions a vailable in ANSY S Fluen t, when t o use them, how to define them, and ho w to define b oundar y pr ofiles and v olumetr ic sour ces and fix the v alue of a v ariable in a par ticular r egion. It also c ontains inf ormation ab out p orous media and lump ed par amet er mo dels . •Physical Properties (p.1079 ), descr ibes the ph ysical pr operties of ma terials and the equa tions tha t ANSY S Fluen t uses t o comput e the pr operties fr om the inf ormation tha t you input. •Modeling B asic F luid F low (p.1197 ), descr ibes the go verning equa tions and ph ysical mo dels used b y ANSY S Fluen t to comput e fluid flo w (including p eriodic flo w, swir ling and r otating flo ws, compr essible flo ws, and inviscid flo ws), as w ell as the inputs y ou need t o pr ovide t o use these mo dels . •Modeling F lows with M oving R eference Frames (p.1227 ), descr ibes the use of single mo ving r eference frames , multiple mo ving r eference frames , and mixing planes in ANSY S Fluen t. •Modeling F lows Using S liding and D ynamic M eshes (p.1251 ), descr ibes the use of sliding and def orming meshes in ANSY S Fluen t. •Modeling Turbulenc e (p.1375 ), descr ibes the use of the turbulen t flo w mo dels in ANSY S Fluen t. •Modeling H eat Transf er (p.1467 ), descr ibes the use of the ph ysical mo dels in ANSY S Fluen t to comput e hea t transf er(including c onvective and c onduc tive hea t transf er, natural convection, radia tive hea t transf er, and periodic hea t transf er), as w ell as the inputs y ou need t o pr ovide t o use these mo dels •Modeling H eat Exchangers (p.1573 ), descr ibes the use of the hea t exchanger mo dels in ANSY S Fluen t.•Modeling S pecies Transp ort and F inite-Rate Chemistr y (p.1613 ), descr ibes the use of the finit e-rate chemistr y models in ANSY S Fluen t.This chapt er also pr ovides inf ormation ab out mo deling sp ecies tr ansp ort in non- reacting flo ws. •Modeling N on-P remix ed C ombustion (p.1687 ), descr ibes the use of the non-pr emix ed c ombustion mo del in ANSY S Fluen t.This chapt er includes details ab out using pr ePDF . •Modeling P remix ed C ombustion (p.1749 ), descr ibes the use of the pr emix ed c ombustion mo del in ANSY S Fluen t. •Modeling P artially P remix ed C ombustion (p.1759 ), descr ibes the use of the par tially pr emix ed c ombustion model in ANSY S Fluen t. •Modeling a C omp osition PDF Transp ort Problem (p.1779 ), descr ibes the use of the c omp osition PDF tr ansp ort model in ANSY S Fluen t. •Using C hemistr y Acceleration (p.1793 ), descr ibes the use of metho ds to acc elerate computa tions f or detailed chemic al mechanisms in volving laminar and turbulen t flames . •Modeling Engine Ignition (p.1807 ), descr ibes the use of the engine ignition mo dels in ANSY S Fluen t. •Modeling P ollutan t Formation (p.1823 ), descr ibes the use of the mo dels f or the f ormation of NO x, SOx, and soot in ANSY S Fluen t. •Predic ting A erodynamic ally G ener ated N oise (p.1875 ), descr ibes the use of the ac oustics mo del in ANSY S Fluen t. •Modeling D iscrete Phase (p.1911 ), descr ibes the use of the discr ete phase mo dels in ANSY S Fluen t. •Modeling M acroscopic P articles (p.2071 ), descr ibes the use of the macr oscopic par ticle mo dels in ANSY S Fluen t. •Modeling M ultiphase F lows (p.2091 ), descr ibes the use of the gener al multiphase mo dels in ANSY S Fluen t (VOF, mixture, and E uler ian). •Popula tion B alanc e Model (p.2285 ), descr ibes the use of the p opula tion balanc e mo dels in ANSY S Fluen t. •Modeling S olidific ation and M elting (p.2321 ), descr ibes the use of the solidific ation and melting mo del in ANSY S Fluen t. •Modeling F luid-S tructure Interaction (FSI) Within F luen t (p.2329 ), descr ibes the use of a str uctural mo del f or intrinsic fluid-str ucture interaction (FSI) simula tions in ANSY S Fluen t. •Modeling E uler ian Wall F ilms (p.2337 ), descr ibes the use of the E uler ian w all film mo del in ANSY S Fluen t. •Modeling E lectric Potential F ield (p.2351 ), descr ibes the use of the elec tric potential mo del in ANSY S Fluen t. •Modeling B atteries (p.2355 ), descr ibes the use of the ba ttery mo dels in ANSY S Fluen t. •Modeling F uel C ells (p.2409 ), descr ibes the use of the fuel c ell mo dels in ANSY S Fluen t. •Modeling M agnet ohydrodynamics (p.2493 ), descr ibes the use of the magnet ohydrodynamics mo dels in ANSY S Fluen t. •Modeling C ontinuous F ibers (p.2515 ), descr ibes the use of the c ontinuous fib er mo del in ANSY S Fluen t.•Creating R educ ed Or der M odels (R OMs) (p.2551 ), descr ibes the use of the r educ ed or der mo del in ANSY S Fluen t. •Using the S olver (p.2559 ), descr ibes the use of the ANSY S Fluen t solv ers. •Adapting the M esh (p.2705 ), descr ibes the use of the solution-adaptiv e mesh r efinemen t feature in ANSY S Fluen t. •Creating Sur faces and C ell R egist ers f or D ispla ying and R eporting D ata (p.2727 ), descr ibes ho w to create surfaces in the domain on which y ou c an e xamine ANSY S Fluen t solution da ta. •Displa ying G raphics (p.2775 ), descr ibes the use of the gr aphics t ools t o examine y our ANSY S Fluen t solution. •Reporting A lphanumer ic D ata (p.2909 ), descr ibes ho w to obtain r eports of flux es, forces, surface integrals, and other solution da ta. •Field F unction D efinitions (p.2959 ), descr ibes the flo w variables tha t app ear in the v ariable selec tion dr op- down lists in ANSY S Fluen t dialo g boxes, and t ells y ou ho w to create your o wn cust om field func tions . •Parallel P rocessing (p.3045 ), descr ibes the use of the par allel pr ocessing f eatures in ANSY S Fluen t.This chapt er also pr ovides inf ormation ab out par titioning y our mesh f or par allel pr ocessing . •Design A naly sis and Optimiza tion (p.3105 ), descr ibes the use of the adjoin t solv er and the mesh mor pher/op- timiz er.These f eatures allo w you t o mo dify the design and solv e optimiza tion pr oblems in ANSY S Fluen t. •Performing S ystem C oupling S imula tions U sing F luen t (p.3207 ), descr ibes c onnec ting ANSY S Fluen t to external solv ers. •Customizing F luen t (p.3233 ), provides inf ormation ab out using ANSY S ACT t o create simula tion wizar ds tha t can b e run fr om either stand-alone F luen t or F luen t in Workbench. •Task P age R eference Guide (p.3235 ), descr ibes the use of the task pages within the ANSY S Fluen t user in terface. •Ribbon R eference Guide (p.3745 ), descr ibes the File ribbon tab and other dialo g boxes tha t are available fr om the r ibbon a t the t op of the ANSY S Fluen t user in terface. •Appendix A: ANSY S Fluen t Model C ompa tibilit y (p.3965 ), presen ts a ser ies of tables outlining the c ompa tibilit y of se veral ANSY S Fluen t mo del c ategor ies. •Appendix B: ANSY S Fluen t File F ormats (p.3969 ), presen ts inf ormation ab out the c ontents and f ormats of ANSY S Fluen t case, data, and mesh mor pher/optimiz er files . •Appendix C: Controlling CHEMKIN-CFD S olver Paramet ers U sing Text Commands (p.3989 ), descr ibes the available t ext commands tha t can b e used t o control or impr ove the p erformanc e and c onvergenc e behavior of the CHEMKIN-CFD solv er withinANSY S Fluen t, as w ell as their default v alues and their r ecommended use . •Appendix D: Nomencla ture (p.4001 ), presen ts a br ief listing of the ph ysical pr operties and fluid d ynamic quan tities used thr oughout the ANSY S Fluen t do cumen tation. •Biblio graph y (p.4005 ) presen ts the biblio graph y for the pr evious chapt ers.Using This M anual This pr efac e is divided in to the f ollowing sec tions: 1.Typographic al Conventions 2. Mathema tical Conventions 1.Typographic al C onventions Several typographic al conventions ar e used in this manual ’s text to help y ou find c ommands in the user in terface. •Different type styles ar e used t o indic ate gr aphic al user in terface items and t ext interface items . For example: Iso-S urface dialo g box surface/iso-surface text command •The t ext interface type style is also used when illustr ating e xactly wha t app ears on the scr een t o distin- guish it fr om the nar rative text. In this c ontext, user inputs ar e typic ally sho wn in b oldfac e. For e xample , solve/initialize/set-fmg-initialization Customize your FMG initialization: set the number of multigrid levels [5] set FMG parameters on levels .. residual reduction on level 1 is: [0.001] number of cycles on level 1 is: [10] 100 residual reduction on level 2 is: [0.001] number of cycles on level 2 is: [50] 100 •Mini flo w char ts ar e used t o guide y ou thr ough the r ibbon or the tr ee, leading y ou t o a sp ecific option, dialo g box, or task page .The following tables list the meaning of each symb ol in the mini flo w char ts. Table 5: Mini F low C har t Symb ol D escr iptions Indic ated A ction Symb ol Look a t the r ibbon Look a t the tr ee Double-click t o op en task page Selec t from task page Right-click the pr eceding it em For e xample , Setting U p D omain → Mesh → Transf orm → Transla te... dxlvRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.indic ates selec ting the Setting U p D omain ribbon tab , click ing Transf orm (in the Mesh group box) and selec ting Transla te..., as indic ated in the figur e below: And Setup → Models → Visc ous Model → Realizable k-epsilon indic ates e xpanding the Setup and Models branches , right-click ing Visc ous , and selec ting Realizable k-epsilon from the Model sub-menu , as sho wn in the f ollowing figur e: And Setup → Boundar y Conditions → velocity-inlet-5 indic ates op ening the task page as sho wn b elow: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. dxlviUsing This M anualIn this manual, mini flo w char ts usually acc ompan y a descr iption of a dialo g box or c ommand , or a scr een illustr ation sho wing ho w to use the dialo g box or c ommand .They sho w you ho w to quick ly acc ess a c ommand or dialo g box without ha ving t o sear ch the sur rounding ma terial. •In-text references to File ribbon tab selec tions c an b e indic ated using a “/”. For e xample File/W rite/Case... indic ates click ing the File ribbon tab and selec ting Case... from the Write submenu (which op ens the Selec t File dialo g box). 2. Mathema tical C onventions •Where possible , vector quan tities ar e displa yed with a r aised ar row (e .g., , ). Boldfac ed char acters ar e re- served f or v ectors and ma trices as the y apply t o linear algebr a (e.g., the iden tity ma trix, ). •The op erator , referred t o as gr ad, nabla, or del, represen ts the par tial der ivative of a quan tity with r espect to all dir ections in the chosen c oordina te sy stem. In C artesian c oordina tes, is defined t o be (8) app ears in se veral w ays: –The gr adien t of a sc alar quan tity is the v ector whose c omp onen ts ar e the par tial der ivatives; for e xample , (9) –The gr adien t of a v ector quan tity is a sec ond-or der t ensor ; for e xample , in C artesian c oordina tes, dxlviiRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Mathema tical Conventions(10) This t ensor is usually wr itten as (11) –The div ergenc e of a v ector quan tity, which is the inner pr oduc t between and a v ector; for e xample , (12) –The op erator , which is usually wr itten as and is k nown as the Laplacian; for e xample , (13) is diff erent from the e xpression , which is defined as (14) •An exception t o the use of is found in the discussion of R eynolds str esses in Turbulenc e in the Fluent Theor y Guide , wher e convention dic tates the use of C artesian t ensor nota tion. In this chapt er, you will also find tha t some v elocity vector comp onen ts ar e wr itten as , , and inst ead of the c onventional with directional subscr ipts. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. dxlviiiUsing This M anualChapt er 1: Graphic al U ser In terface (GUI) The F luen t graphic al in terface consists of a r ibbon (tabs), a toolbar , a tr ee, a task page , a gr aphics t oolbar , graphics windo ws, and a c onsole , which is a t extual c ommand line in terface (descr ibed in Text User Interface (TUI) (p.579)).You will also ha ve acc ess t o the dialo g boxes via the r ibbon or task pages . 1.1. GUI C omp onen ts 1.2. Modifying the G raphic al User In terface 1.3. Setting U ser P references/Options 1.4. Fluen t Graphic al User In terface in Japanese 1.5. Using the H elp S ystem 1.1. GUI C omp onen ts The gr aphic al user in terface (GUI) is made up of se ven main c omp onen ts, which ar e descr ibed in detail in the subsequen t sec tions: the r ibbon, the tr ee, toolbars , task pages , a console , dialo g boxes, and graphics windo ws.When y ou use the GUI, you will b e in teracting with one of these c omp onen ts at all times .The GUI will change dep ending on whether y ou ar e in meshing mo de (as descr ibed in the F luen t Meshing sec tion of the U ser’s Guide) or solution mo de (as descr ibed in this guide , and as sho wn in Figur e 1.1: The GUI C omp onen ts (p.550)). For details on ho w to swit ch b etween these mo des, see Switching B etween M eshing and S olution M odes (p.59) in the Getting S tarted G uide . Many of the GUI elemen ts can b e mo ved or tabb ed t ogether t o suit y our pr eferences.You c an also modify a ttribut es of the GUI t o better ma tch y our pla tform en vironmen t.These ar e descr ibed in Modi- fying the G raphic al U ser In terface (p.573) and Setting U ser P references/Options (p.573). 549Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Figur e 1.1: The GUI C omp onen ts For additional inf ormation, see the f ollowing sec tions: 1.1.1. The R ibbon 1.1.2. The Outline View 1.1.3. Graphics Windo ws 1.1.4. Quick S earch 1.1.5. Toolbars 1.1.6. Task P ages 1.1.7. The C onsole 1.1.8. Dialog Boxes 1.1.1. The R ibbon The r ibbon, located a t the t op of the F luen t GUI, is the pr imar y metho d for setting up and r unning your simula tion. It facilita tes acc ess t o the most c ommonly used it ems , with tabs nominally ar ranged in a lef t to right workflow for a t ypic al simula tion. Contents within each tab ar e gr oup ed with r elated content and ar e or ganiz ed lo gically t o acc ommo date varied pr ojec ts and pr iorities .You ha ve the option to minimiz e the r ibbon b y click ing , located t o the r ight of the r ibbon tabs . Figur e 1.2: The F luen t Ribbon Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 550Graphic al User In terface (GUI)Often, mak ing a selec tion in the r ibbon op ens a dialo g box. In some instanc es, a ribbon selec tion op ens a task page . 1.1.2. The Outline View The outline view tr ee, located on the lef t side of the F luen t GUI, is an in teractive represen tation of your pr ojec t. Its it ems ar e list ed in an or der tha t complemen ts the t ypic al pr oblem setup y ou f ollow in the r ibbon. Branches c an b e expanded and c ollapsed t o suit y our pr eferences. You c an selec t multiple r elated it ems b y lef t-click ing and dr agging or using Shift/Ctrl + lef t-click. Right- click ing selec ted it ems in the tr ee pr ovides a list of c ommon c ommands .Typographic al C onven- tions (p.dxlv ) sho ws the c onvention used t o descr ibe this r ight-click ac tion, when it is r eferred t o in the documen tation. Figur e 1.3: The F luen t Outline View You c an p erform wildc ard and r egular e xpression sear ches in the tr ee using the filt er text en try box at the t op of the tr ee; see Filter Text En try Boxes (p.565) for additional inf ormation. Double-click ing man y of the br anches under Setup ,Solution , or Results displa ys the c orresponding Task P age to the r ight of the tr ee. For additional inf ormation, see ( Task P ages (p.560)). 551Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.GUI C omp onen tsDrag and D rop, Copy and P aste There ar e multiple uses f or dr ag and dr op op erations with a r unning F luen t session. You c an use dr ag and dr op t o: •Open files b y dr opping them on to the op en F luen t session. The supp orted file t ypes include: –Case and da ta (*.cas ,*.cas.gz ,*.dat ,*.dat.gz ,*.msh ,*.msh.gz ) –Journals (*.jou ,*.log ) –Profiles (*.csv ) –PDFs (*.pdf ) •Copy various settings and objec ts within a F luen t session and acr oss F luen t sessions . For e xample , you c an drag a r eport definition fr om one session and dr op it on another op en F luen t session. This r eport definition will then b e created in the new session. Note that F luent displa ys a plus ( ) icon f or v alid dr op op erations and a in valid ( ) icon f or op erations or lo cations that ar e not allo wed. •Displa y items in the gr aphics windo w by dr agging them fr om the tr ee and dr opping them on the gr aphics windo w.This func tions lik e the Add t o gr aphics right-click option. Copy and past e is a vailable f or c opying it ems fr om the outline view t o the clipb oard so tha t you c an past e them elsewher e in the same session or in to another session without ha ving t o hold do wn the left-mouse-butt on lik e you do f or a dr ag and dr op op eration. Copy and past e is a vailable f or: •Boundar y conditions •Named e xpressions •Report definitions , files , and plots •Postpr ocessing objec ts (mesh, contours , and so on) Export To File and Imp ort From F ile Export To File... and Imp ort From F ile... are available as r ight-click options f or c ertain br anches in the outline view , including: •Boundar y conditions •Named e xpressions •Report definitions •Postpr ocessing objec ts These options allo w you t o sa ve the settings of a single sub-br anch (f or e xample , a single b oundar y condition or named e xpression) or all of the it ems in the higher-le vel br anch (f or e xample , all of the boundar ies or all of the named e xpressions) f or la ter use .These e xports ar e sa ved in .tsv format . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 552Graphic al User In terface (GUI)1.1.3. Graphics Windo ws Graphics windo ws displa y the pr ogram’s graphic al output , and ma y be view ed within the F luen t ap- plication windo w or in separ ate windo ws.You c an r ight-click the t op of the gr aphics windo w to selec t whether y ou w ant new gr aphics windo ws to be tabb ed or as additional sub-windo ws within the graphics windo w gr oup spac e. By default , graphics windo ws view ed within the applic ation windo w will b e plac ed b elow the t oolbar on the r ight, as sho wn in Figur e 1.1: The GUI C omp onen ts (p.550). Using c ontext menus in the gr aphics windo w you c an acc ess and mo dify settings dir ectly on the model. Figur e 1.4: Graphics Windo w C ontext Menu: Single-S elec tion (p.553) and Figur e 1.5: Graphics Windo w C ontext Menu: Multiple-S elec tion (p.554) demonstr ate some of the options a vailable via r ight- click. You c an mak e multiple selec tions on the displa yed gr aphics objec t by holding Ctrl . Figur e 1.4: Graphics Windo w C ontext Menu: Single-S elec tion Figur e 1.4: Graphics Windo w C ont ext Menu: Single-S elec tion (p.553 ) sho ws right-click ing the inlet (selec tion highlight ed in gr een) and sp ecifying it as a pressur e-inlet . 553Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.GUI C omp onen tsFigur e 1.5: Graphics Windo w C ontext Menu: Multiple-S elec tion Figur e 1.5: Graphics Windo w C ont ext Menu: Multiple-S elec tion (p.554 ) sho ws right-click ing the objec t when multiple sur faces ar e selec ted and a sc ene is displa yed. Note There ar e a f ew situa tions wher e a r ight-click in the gr aphics windo w will not op en a c ontext menu: •Right-mouse-butt on (RMB) is set as mouse-pr obe and y ou r ight-click on the mo del when nothing is selec ted. •RMB is set as mouse-pr obe and long descr iption and y ou r ight-click an ywher e in the gr aphics windo w when nothing is selec ted. •RMB is set as mouse-z oom. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 554Graphic al User In terface (GUI)For additional inf ormation on mouse butt on settings , see Controlling the M ouse B utton Functions (p.2833 ). In Figur e 1.6: Displa ying Two Graphics Windo ws (p.555), two gr aphics windo ws are displa yed b y right- click ing the t op of the gr aphics windo w and selec ting SubW indo w View, then cr eating t wo gr aphic al displa ys and fitting them in the spac e acc ordingly . Figur e 1.6: Displa ying Two G raphics Windo ws The Displa y Options dialo g box (see Displa y Options D ialog Box (p.3681 )) can b e used t o change the attribut es of the gr aphics windo w or t o op en another gr aphics windo w. In the View tab ( Mouse group 555Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.GUI C omp onen tsbox), you c an set the ac tion tak en in the gr aphics windo w when a mouse butt on is pr essed (see Modifying the M ouse B utton F unctions (p.2834 ) for details). Imp ortant To cancel a displa y op eration, press Ctrl+c while the da ta is b eing pr ocessed in pr epar ation for gr aphic al displa y.You c annot c ancel the op eration af ter the pr ogram b egins t o dr aw in the gr aphics windo w. Imp ortant It is p ossible tha t the gr aphics windo w ma y become [Out of D ate] (which w ould b e indic ated at the t op of the gr aphics windo w), if y ou mak e changes t o items tha t are alr eady displa yed. To resolv e this out of da te sta te, right-click in the gr aphics windo w and click Refr esh D ispla y in the c ontext menu tha t app ears . If a c ont ext menu do es not app ear on a r ight-click of the gr aphics windo w, ensur e that the r ight- mouse butt on is set t o an ac tion other than mouse-z oom or mouse-pr obe and long description (Vie w ribbon tab ,Mouse group b ox). Copy to Clipb oar d Right-click ing the gr aphics windo w tab allo ws you t o selec t Copy to Clipb oard.This plac es a c opy of the cur rent pic ture displa yed in the selec ted gr aphics windo w tab on to your clipb oard.The siz e of your gr aphics windo w aff ects the siz e of the t ext fonts used in the pic ture. 1.1.4. Quick S earch The sear ch bar (upp er right of the F luen t windo w or via Ctrl + F) allo ws you t o quick ly lo cate the commands or c ontrols tha t you ar e lo oking f or. Clicking the sear ch r esults is equiv alen t to click ing the same c ontrol in the r ibbon. Hovering o ver a sear ch r esult highligh ts the lo cation of the c ontrol in the ribbon. Clicking a t ext command sear ch r esult aut oma tically en ters the t ext of the c ommand , but it does not e xecut e the c ommand; you still ha ve to pr ess Enter in the c onsole t o execut e the t ext com- mand . 1.1.5. Toolbars The F luen t GUI includes t oolbars lo cated within the applic ation windo w.These t oolbars pr ovide shor tcuts t o performing c ommon tasks in F luen t.The t oolbars include a standar d toolbar and an objec ts toolbar . 1.1.5.1. The Standar d Toolbar The standar d toolbar ( Figur e 1.7: The S tandar d Toolbar (p.556)) contains options f or getting help , ar- ranging the gr aphic al user in terface, and visiting the ANSY S websit e. Figur e 1.7: The S tandar d Toolbar Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 556Graphic al User In terface (GUI)The f ollowing is a br ief descr iption of each of the standar d toolbar options: •Help allo ws you t o acc ess the F luen t User's G uide (p.1) for help t opics . For mor e inf ormation, see Using the H elp S ystem (p.576). •Arrange the w orkspac e provides y ou with se veral applic ation windo w la yout options . For e xample , you c an cho ose t o hide c ertain windo ws or ha ve the gr aphics windo w be much lar ger than the other elemen ts.These options also allo w you t o retur n to a standar d layout if y ou acciden tally r earrange (b y dragging and dr opping , or closing elemen ts) the w orkspac e in an undesir able manner . •Link t o the ANSY S Websit e opens a link t o the ANSY S home page in y our default br owser. 1.1.5.2. The Gr aphics Toolbar Figur e 1.8: The G raphics Toolbar The f ollowing t ools ar e available in the gr aphics t oolbar : 1.1.5.2.1. Pointer Tools 1.1.5.2.2. View Tools 1.1.5.2.3. Projec tion Tools 1.1.5.2.4. Mesh D ispla y Configur ation 1.1.5.2.5. Additional D ispla y Options 1.1.5.2.1. Point er Tools The p ointer tools ( Figur e 1.9: The P ointer Tools (p.557)) allo w you t o mo dify the w ay in which y ou view y our mo del or selec t objec ts in the gr aphics windo w. Figur e 1.9: The P ointer Tools The f ollowing is a descr iption of each of the p ointer tools: •Rota te View lets y ou r otate your mo del ab out a c entral point in the gr aphics windo w. For mor e information, see Button F unctions (p.2833 ). •Pan allo ws you t o pan hor izontally or v ertically acr oss the view using the lef t mouse butt on. For mor e inf ormation, see Button F unctions (p.2833 ). •Zoom In/Out allo ws you t o zoom in t o and out of the mo del b y holding the lef t mouse butt on down and mo ving the mouse do wn or up . For mor e inf ormation, see Button F unctions (p.2833 ).You c an also r oll the view b y holding the lef t mouse butt on do wn and mo ving the mouse lef t or r ight. 557Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.GUI C omp onen ts•Zoom t o Area allo ws you t o focus on an y par t of y our mo del. After selec ting this option, position the mouse p ointer at a c orner of the ar ea to be magnified , hold do wn the lef t mouse butt on and dr ag open a b ox to the desir ed siz e, and then r elease the mouse butt on.The enclosed ar ea will then fill the graphics windo w. Note tha t you must dr ag the mouse t o the r ight in or der t o zoom in. To zoom out , you must dr ag the mouse t o the lef t. For mor e inf ormation, see Button F unctions (p.2833 ). •Print inf ormation ab out selec ted it em allo ws you t o selec t items fr om the gr aphics windo ws and request inf ormation ab out displa yed sc enes .This b ehaves as a mouse pr obe butt on. For mor e inf ormation, see Button F unctions (p.2833 ). 1.1.5.2.2. View Tools The view t ools ( Figur e 1.10: The View Tools (p.558)) allo w you t o mo dify the w ay your mo del is dis- played in the gr aphics windo w. Figur e 1.10: The View Tools The f ollowing is a descr iption of each of the view t ools: •Fit to Windo w adjusts the o verall siz e of y our mo del t o tak e maximum ad vantage of the gr aphics windo w’s width and heigh t. •Last View allo ws you t o revert to the displa yed objec ts pr evious lo cation and or ientation in the graphics windo w. •Set vie w contains a dr op-do wn of view s, allo wing y ou t o displa y the mo del fr om the dir ection of the v ector equidistan t to all thr ee ax es, as w ell as in diff erent axes or ientations . •Save Picture allo ws you t o captur e an image of the ac tive gr aphics windo w. For mor e inf ormation, see Saving P icture Files (p.645). 1.1.5.2.3. Projec tion Tools The pr ojec tion t ools ( Figur e 1.11: The P rojec tion Tools (p.558)) allo w you t o mo dify the p ersp ective of objec ts in the gr aphics windo w. Figur e 1.11: The P rojec tion Tools The f ollowing is a br ief descr iption of each of the pr ojec tion t ools: •Persp ective View sho ws the 3D objec t on y our 2D scr een appr oxima tely ho w your e ye would see it in r eal lif e.This butt on is only a vailable when r unning F luen t in 3D . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 558Graphic al User In terface (GUI)•Ortho graphic View sho ws 3D objec ts to sc ale, ignor ing p ersp ective view .When enabled , it mak es it so the r uler is accur ate.This butt on is only a vailable when r unning F luen t in 3D . Note When Ortho graphic is selec ted f or Graphics vie w in Preferenc es (Appearanc e branch), an additional Ruler option app ears . Enabling Ruler mak es it so tha t the r uler is displa yed whene ver the view is changed t o or thographic .You c an still disable the r uler b y toggling the r uler butt on ). 1.1.5.2.4. Mesh D ispla y Configur ation The mesh displa y configur ation options ( Figur e 1.12: Mesh D ispla y Configur ation (p.559)) contains predefined settings f or ho w a mesh and objec ts ar e displa yed. Figur e 1.12: Mesh D ispla y Configur ation The f ollowing is a br ief descr iption of the c onfigur ation options: •Mesh D ispla y Configur ation contains options f or changing ho w the mesh displa ys in the gr aphics windo w. –Meshing draws mesh on edges and fac es of the outline sur faces, color ed b y their z one ID with ligh ting enabled . –Solution draws mesh on edges and fac es of the outline sur faces, color ed b y their z one t ype with ligh ting enabled . –Post P rocessing draws the objec t outline with ligh ting disabled . –Classic draws mesh on all edges of the outline sur faces. 1.1.5.2.5. Additional D ispla y O ptions The additional displa y options ( Figur e 1.13: Additional D ispla y Options (p.560)) provides acc ess t o the Mesh D ispla y Dialog Box (p.3239 ) and the abilit y to mak e the out er fac es tr anspar ent. 559Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.GUI C omp onen tsFigur e 1.13: Additional D ispla y Options The f ollowing is a descr iption of each of the additional displa y options: •Ruler Visibilit y turns the r uler on and off .When enabled , it swit ches the view t o ortho graphic (if it was pr eviously set t o persp ective). •Mesh D ispla y opens the Mesh D ispla y Dialog Box (p.3239 ). •Front Faces Transpar ent mak es the fr ont fac es of the displa yed objec t transpar ent, allo wing y ou to see inside . •Axes Visibilit y turns the ax es displa y on and off . •Titles Visibilit y turns the titles displa y on and off . •Copy to Clipb oard copies the cur rent pic ture displa yed in the selec ted gr aphics windo w tab on to your clipb oard. 1.1.6. Task P ages Task pages app ear on the r ight side of the tr ee when c ertain br anches ar e double-click ed.They pr ovide access t o mor e ad vanced settings than ar e of ten a vailable thr ough a r ight-click of the same br anch or sub-br anches .The e xpected w orkflow is tha t you tr avel do wn the tr ee, using a r ight-click most br anches and sub-br anches t o acc ess the settings and c ontrols r equir ed f or to solv e your pr oblem. Some of y our setup will o ccur in dialo g boxes, while others in task pages . For e xample , if y ou double- click Gener al in the tr ee, the Gener al Task P age (p.3235 ) is displa yed. Global settings ar e made in this task page , which ar e sa ved t o the c ase definition. Each task page has a Help butt on. Clicking this butt on op ens the r elated help t opic in the Task P age Reference Guide (p.3235 ). See Using the H elp S ystem (p.576) for mor e inf ormation. 1.1.7. The C onsole The c onsole is lo cated b elow the gr aphics windo w, as sho wn in Figur e 1.1: The GUI C omp onen ts (p.550). Fluen t communic ates with y ou thr ough the c onsole . It is used t o displa y various k inds of inf ormation (tha t is, messages r elating t o meshing or solution pr ocedur es, and so on). Console t ext is c olor ed based on whether it is user-input , standar d output , or a w arning message . Fluen t saves a c ertain amoun t of information tha t is wr itten t o the c onsole in to memor y.You c an r eview this inf ormation a t an y time by using the scr oll bar on the r ight side of the c onsole .You c an enable/disable aut oscr olling using the check b ox at the b ottom r ight of the c onsole t o either ha ve the cursor jump t o the la test pr inted content or sta y wher e it is .The siz e of the c onsole c an b e adjust ed b y raising or lo wering the b ottom frame of the gr aphics windo w. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 560Graphic al User In terface (GUI)The c onsole is similar in b ehavior t o “xterm” or other Linux c ommand shell t ools, or t o the MS-DOS Command P rompt windo w on Windo ws systems . It allo ws you t o in teract with the TUI menu . More information on the TUI c an b e found in Text User In terface (TUI) (p.579). The c onsole acc epts a “break” command (pr essing Ctrl+c at the same time) t o let y ou in terrupt the program while it is w orking. It also lets y ou p erform text copy and past e op erations b etween the console and other X Windo w (or Windo ws) applic ations tha t supp ort copy and past e.The f ollowing steps sho w you ho w to perform a c opy and past e op eration on a Windo ws system: 1.Move the p ointer to the b eginning of the t ext to be copied . 2.Press and hold do wn the lef t mouse butt on. 3.Move the p ointer to the end of the t ext (text should b e highligh ted). 4.Release the lef t mouse butt on. 5.Press the Ctrl and keys at the same time . 6.Move the p ointer to the tar get windo w and click the lef t mouse butt on. 7.Press the Ctrl+v keys at the same time . On a Linux sy stem, you will f ollow the st eps b elow to copy text to the clipb oard: 1.Move the p ointer to the b eginning of the t ext to be copied . 2.Press and hold do wn the lef t mouse butt on. 3.Move the p ointer to the end of the t ext (text should b e highligh ted). 4.Release the lef t mouse butt on. 5.Move the p ointer to the tar get windo w. 6.Press the middle mouse butt on t o “past e” the t ext. Note The c onsole has a 30,000 line r etention limit. Onc e the numb er of lines passes 30,000, the auto-scr oll check box (lo wer right of the C onsole) no longer has an eff ect. 1.1.8. Dialo g Boxes There ar e two types of dialo g boxes in F luen t. Some dialo g boxes ar e used t o perform simple input/out- put tasks , such as issuing w arning and er ror messages , or ask ing a question r equir ing a y es or no answ er. Other f orms of dialo g boxes allo w you t o perform mor e complic ated input tasks . A dialo g box is a separ ate “temp orary” windo w tha t app ears when F luen t needs t o communic ate with you, or when v arious t ypes of input c ontrols ar e emplo yed t o set up y our c ase.The t ypes of c ontrols you will see ar e descr ibed fur ther in this sec tion. 561Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.GUI C omp onen tsWhen y ou ha ve finished en tering da ta in a dialo g box’s controls, you must apply the changes y ou have made , or c ancel the changes , if desir ed. For this task, each dialo g box falls in to one of t wo beha- vior al categor ies, dep ending on ho w it w as designed . The first c ategor y of dialo g boxes is used in situa tions wher e it is desir able t o apply the changes and immedia tely close the dialo g box.This t ype of dialo g box includes an OK and a Canc el butt on tha t func tion as descr ibed b elow: OK applies an y changes y ou ha ve made t o the dialo g box, then closes the dialo g box. Canc el closes the dialo g box, ignor ing an y changes y ou ha ve made . An example of this t ype of dialo g box is sho wn in the f ollowing figur e: The other c ategor y of dialo g boxes is used in situa tions wher e it is desir able t o keep the dialo g box displa yed on the scr een af ter changes ha ve been applied .This mak es it easy t o quick ly go back t o tha t dialo g box and mak e mor e changes . Dialog boxes used f or p ostpr ocessing and mesh adaption of ten fall in to this c ategor y.This t ype of dialo g box typic ally includes an Apply butt on and a Close butt on as descr ibed b elow: Apply applies an y changes y ou ha ve made t o the dialo g box, but do es not close the dialo g box.The name of this butt on is of ten changed t o something mor e descr iptiv e. For e xample , man y of the p ostpr ocessing dialo g boxes use the name Displa y for this butt on, and the adaption dialo g boxes use the name Adapt . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 562Graphic al User In terface (GUI)Close closes the dialo g box. An example of this t ype of dialo g box is sho wn in the f ollowing figur e: All dialo g boxes include the f ollowing butt on used t o acc ess ANSY S Help: Help displa ys inf ormation ab out the c ontrols in the dialo g box.The inf ormation app ears in the ANSY S Help Viewer. Many dialo g boxes also pr esen t additional butt ons t o acc omplish sp ecific tasks or op en additional dialo g boxes.You c an find descr iptions of the func tions of these additional butt ons in Ribbon R eference Guide (p.3745 ) or Task P age R eference Guide (p.3235 ). Note Dialog boxes c ontaining lists ar e expandable . 563Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.GUI C omp onen ts1.1.8.1. Input C ontr ols Each t ype of input c ontrol utiliz ed b y the dialo g boxes is descr ibed b elow. Note tha t the e xamples shown her e ar e for a Windo ws system; if y ou ar e working on a Linux sy stem, your dialo g box controls may look sligh tly diff erent, but the y will w ork exactly as descr ibed her e. 1.1.8.1.1. Tabs Much lik e the tabs on a not ebook divider , tabs in dialo g boxes ar e used t o mar k the diff erent sec tions into which a dialo g box is divided . A dialo g box tha t contains man y controls ma y be divided in to different sec tions t o reduc e the amoun t of scr een spac e it o ccupies .You c an acc ess each sec tion of the dialo g box by “click ing” the lef t mouse butt on on the c orresponding tab . A click is one pr ess and r elease of the mouse butt on. 1.1.8.1.2. Butt ons A butt on, also r eferred t o as a push butt on, is used t o perform a func tion indic ated b y the butt on label.To ac tivate a butt on, plac e the p ointer o ver the butt on and click the lef t mouse butt on. 1.1.8.1.3. Check B oxes A check b ox, also r eferred t o as a check butt on, is used t o enable / disable an it em or ac tion indic ated by the check b ox lab el. Click the lef t mouse butt on on the check b ox to toggle the sta te. 1.1.8.1.4. Radio Butt ons Radio butt ons ar e a set of check b oxes with the c ondition tha t only one c an b e set in the “on” pos- ition a t a time .When y ou click the lef t mouse butt on on a r adio butt on, it will b e tur ned on, and all others will b e tur ned off . Radio butt ons app ear either as diamonds (in Linux sy stems) or as cir cles (as sho wn ab ove). 1.1.8.1.5. Text Entry Boxes A text en try box lets y ou t ype text input. It will of ten ha ve a lab el asso ciated with it t o indic ate the purpose of the en try. 1.1.8.1.6. Integer Numb er E ntry Boxes Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 564Graphic al User In terface (GUI)An in teger numb er en try box is similar t o a t ext en try except it only allo ws integer numb ers t o be entered (f or e xample , 10, -10, 50000 and 5E4). You ma y find it easier t o en ter lar ge in teger numb ers using scien tific nota tion. For e xample , you c ould en ter 350000 or 3.5E5 . The in teger numb er en try also has ar row butt ons tha t allo w you t o easily incr ease or decr ease its value . For most in teger numb er en try controls, the v alue will b e incr eased (or decr eased) b y one when y ou click an ar row butt on.You c an incr ease the siz e of the incr emen t by holding do wn a keyboard key while click ing the ar row butt on.The k eys used ar e sho wn b elow: Factor of Incr ease Key 10 Shift 100 Ctrl 1.1.8.1.7. Real Numb er E ntry Boxes A real numb er en try box is similar t o a t ext en try, except it only allo ws real numb ers t o be en tered (for e xample , 10, -10.538, 50000.45 and 5.72E-4). In most c ases , the lab el will sho w the units asso ciated with the r eal numb er en try. 1.1.8.1.8. Filter Text Entry Boxes The filt er text en try box allo ws you t o sear ch and or ganiz e a list using a t ext str ing.The t ext str ing can include wildc ards and r egular e xpressions , which allo w you t o perform pa ttern ma tching . For example , sear ching *let* finds sur faces such as in lets and out lets, including those with longer names , such as "upp er-inlet-5". If you ha ve walls separ ated b y a numb er, you c an sear ch example- wall-?-23 , which w ould sho w example-wall-1-23 ,example-wall-2-23 , and so on. Filtering b egins as so on as y ou en ter text. Clicking Enter expands an y sub-br anches c ontaining matches t o the en tered str ing. 1.1.8.1.9. Single-S elec tion Lists A single-selec tion list pr esen ts a list of it ems , with each it em pr inted on a separ ate line .You c an selec t an it em b y placing the p ointer o ver the it em line and click ing with the lef t mouse butt on.The selec ted it em will b ecome highligh ted. Selec ting another it em will deselec t the pr eviously selec ted item in the list. 565Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.GUI C omp onen tsMany dialo g boxes will also acc ept a double-click in or der t o in voke the dialo g box ac tion tha t is asso ciated with the list selec tion (see inf ormation on the dialo g box of in terest f or mor e details). 1.1.8.1.10. Multiple-S elec tion Lists A multiple-selec tion list is similar t o a single-selec tion list , except it allo ws for mor e than one selec ted item a t a time .When y ou click the lef t mouse butt on on an it em, its selec tion sta te will t oggle . Clicking an unselec ted it em will selec t it. Clicking a selec ted it em will deselec t it. To selec t a r ange of it ems in a multiple-selec tion list , you c an selec t the first desir ed it em, and then selec t the last desir ed it em while holding do wn the Shift key.The first and last it ems , and all the items b etween them, will b e selec ted.You c an also click and dr ag the lef t mouse butt on t o selec t multiple it ems . There ar e se veral small butt ons in the upp er right corner of the multiple selec tion list t o acc elerate selec ting or deselec ting it ems fr om the selec tion list. •Click to displa y all of the it ems tha t are cur rently selec ted. •Click or to toggle t o a tr ee view of the selec tion list , and ther eby gr oup it ems b y categor ies such as name or sur face type.You c an selec t or deselec t all the it ems in a par ticular gr oup b y click ing the t op-le vel br anch. For e xample , if y ou ha ve the sur faces gr oup ed b y Surface Type, click ing Inlet will selec t or deselec t all inlets . Note tha t onc e you swit ch t o a tr ee view , the ic on changes t o or , respectively. •Click to selec t all the it ems displa yed in the selec tion list. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 566Graphic al User In terface (GUI)•Click to deselec t all the it ems displa yed in the selec tion list. 1.1.8.1.11. Drop-D own Lists A dr op-do wn list is a hidden single-selec tion list tha t sho ws only the cur rent selec tion t o sa ve spac e. When y ou w ant to change the selec tion, follow the st eps b elow: 1.Click the ar row butt on t o displa y the list. 2.Place the p ointer o ver the new list it em. 3.Click the lef t mouse butt on on the it em t o mak e the selec tion and close the list. If you w ant to stop the selec tion op eration while the list is displa yed, you c an mo ve the p ointer anywher e outside the list and click the lef t mouse butt on. 1.1.8.1.12. Scales A sc ale is used t o selec t a v alue fr om a pr edefined r ange b y mo ving a slider .The numb er sho ws the current value .You c an change the v alue b y click ing the ar row butt ons, or b y following one of the procedur es b elow: 1.Place the p ointer o ver the slider . 2.Press and hold do wn the lef t mouse butt on. 3.Move the p ointer along the slider bar t o change the v alue . 4.Release the lef t mouse butt on. or 1.Place the p ointer o ver the slider and click the lef t mouse butt on. 567Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.GUI C omp onen ts2.Using the ar row keys on the k eyboard, mo ve the slider bar lef t or r ight to change the v alue . 1.1.8.2. Types of D ialo g Boxes The f ollowing sec tions descr ibe the v arious t ypes of dialo g boxes. 1.1.8.2.1. Information D ialo g Boxes The Information dialo g box is used t o report some inf ormation tha t Fluen t thinks y ou should k now. After y ou ha ve read the inf ormation, you c an click the OK butt on t o close the dialo g box. 1.1.8.2.2. Warning D ialo g Boxes The Warning dialo g box is used t o warn you of a p otential pr oblem or deliv er an imp ortant message . Your c ontrol of F luen t will b e susp ended un til you ack nowledge the w arning b y click ing the OK butt on. 1.1.8.2.3. Error D ialo g Boxes The Error dialo g box is used t o aler t you of an er ror tha t has o ccur red. After y ou ha ve read the er ror information, you c an click the OK butt on t o close the dialo g box. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 568Graphic al User In terface (GUI)1.1.8.2.4. The Work ing D ialo g Box The Working dialo g box is displa yed when F luen t is busy p erforming a task. This is a sp ecial dialo g box, because it r equir es no ac tion b y you. It is ther e to let y ou k now tha t you must w ait.When the program is finished , it will close the dialo g box aut oma tically.You c an, however, abort the task tha t is being p erformed b y click ing the Canc el butt on. 1.1.8.2.5. Question D ialo g Box The Question dialo g box is used t o ask y ou a question. Sometimes the question will r equir e a Yes or No answ er, while other times it will r equir e tha t you either allo w an ac tion t o pr oceed ( OK) or Canc el the ac tion. You c an click the appr opriate butt on t o answ er the question. 1.1.8.2.6. The S elec t File D ialo g Box File selec tion is acc omplished using the Selec t File dialo g box (The S elec t File D ialog Box (Win- dows) (p.569) or The S elec t File D ialog Box (Linux) (p.570)). 1.1.8.2.6.1. The S elec t File D ialo g Box (Windo ws) File selec tion on Windo ws systems is acc omplished using the standar d Windo ws Selec t File dialo g box (Figur e 1.14: The S elec t File D ialog Box for Windo ws (p.570)). 569Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.GUI C omp onen tsFigur e 1.14: The S elec t File D ialo g Box for Windo ws See do cumen tation r egar ding y our Windo ws system f or fur ther instr uctions on file selec tion. Note If you ar e acc essing a file using a U niversal N aming C onvention (UNC) pa th, you must ensur e tha t you ha ve permission t o acc ess t o all of the f olders in the pa th or y ou will not be able t o op en the file . 1.1.8.2.6.2. The S elec t File D ialo g Box (Linux) For Linux sy stems , not e tha t the app earance of the Selec t File dialo g box will not alw ays be the same . The v ersion sho wn in Figur e 1.15: The S elec t File D ialog Box for Linux P latforms (p.571) will app ear in almost all c ases , but it will b e diff erent if y ou ar e loading e xternal da ta files f or use in an X Y plot (see Including Ex ternal D ata in the S olution X Y Plot (p.2868 ) for mor e inf ormation). In such c ases , the dialo g box will lo ok lik e Figur e 1.16: Another Version of the S elec t File D ialog Box for Linux P lat- forms (p.571). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 570Graphic al User In terface (GUI)Figur e 1.15: The S elec t File D ialo g Box for Linux P latforms Figur e 1.16: Another Version of the S elec t File D ialo g Box for Linux P latforms 571Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.GUI C omp onen tsThe st eps f or file selec tion ar e as f ollows: 1.Go to the appr opriate dir ectory.You c an do this in t wo diff erent ways: •Enter the pa th to the desir ed dir ectory in the Filter text en try box and then pr ess the Enter key or click the Filter butt on. Be sur e to include the final / char acter in the pa thname , before the optional sear ch pa ttern (descr ibed b elow). •Double-click a dir ectory, and then a sub directory, and so on, in the Directories list un til you r each the dir ectory you w ant.You c an also click onc e on a dir ectory and then click the Filter butt on, inst ead of double-click ing. Note tha t the “ .” item r epresen ts the cur rent dir ectory and the “ ..” item r epresen ts the par ent dir ectory. Note If you ar e acc essing a file using a U niversal N aming C onvention (UNC) pa th, you must ensur e tha t you ha ve permission t o acc ess t o all of the f olders in the pa th or y ou will not b e able t o op en the file . 2.Specify the file name b y selec ting it in the Files list or en tering it in the File text en try box (if a vailable) at the b ottom of the dialo g box.The name of this t ext en try box will change dep ending on the t ype of file y ou ar e selec ting ( Case F ile,Jour nal F ile, and so on). Imp ortant Note tha t if y ou ar e sear ching f or an e xisting file with a nonstandar d extension, you may need t o mo dify the “sear ch pa ttern” at the end of the pa th in the Filter text en try box. For e xample , if y ou ar e reading a da ta file , the default e xtension in the sear ch path will b e *.dat* , and only those files tha t ha ve a .dat extension will app ear in the Files list. If you w ant files with a .DAT extension t o app ear in the Files list, you can change the sear ch pa ttern to *.DAT* . If you w ant all files in the dir ectory to be listed in the Files list, enter just * as the sear ch pa ttern. 3.If you ar e reading a mesh or c ase file , use the Displa y M esh af ter Reading option t o sp ecify whether you w ant Fluen t to aut oma tically displa y the mesh af ter the file is r ead. All of the b oundar y zones will be displa yed, except f or the in terior z ones of 3D geometr ies.The default sta tus of this option (tha t is, enabled or disabled) is det ermined b y your decision r egar ding the Displa y M esh A fter Reading option in Fluen t Launcher . 4.If you ar e using the Replac e M esh... option in the Domain tab ( Zones group b ox) to replac e a mesh with e xisting da ta, you c an enable the Interpolate Data A cross Z ones option t o interpolate the da ta across c ell z ones .This option is appr opriate when the ma tching z one pairs (tha t is, the z ones with the same names in b oth the cur rent mesh and the r eplac emen t mesh) do not ha ve the same in terior z one boundar ies. See Replacing the M esh (p.819) for details . 5.If you ar e reading multiple X Y-plot da ta files , the selec ted file will b e added t o the list of XY File(s) .You can cho ose another file , following the instr uctions ab ove, and it will also b e added t o this list. (If you acciden tally selec t the wr ong file , you c an cho ose it in the XY File(s) list and click the Remo ve butt on to remo ve it fr om the list of files t o be read.) Repeat un til all of the desir ed files ar e in the XY File(s) list. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 572Graphic al User In terface (GUI)6.If you ar e wr iting a c ase, data, or r adia tion file , use the Write Binar y Files check b ox to sp ecify whether the file should b e wr itten as a t ext or binar y file .You c an r ead and edit a t ext file , but it will r equir e mor e storage spac e than the same file in binar y format. Binar y files tak e up less spac e and c an b e read and written b y Fluen t mor e quick ly. 7.Click the OK butt on t o read or wr ite the sp ecified file . Shortcuts f or this st ep ar e as f ollows: •If your file app ears in the Files list and you ar e not reading an X Y file , double-click it inst ead of just selec ting it. This will aut oma tically ac tivate the OK butt on. (If you ar e reading an X Y file , you will alw ays have to click OK yourself . Clicking or double-click ing will just add the selec ted file t o the XY File(s) list.) •If you en tered the name of the file in the File text en try box, you c an pr ess the Enter key inst ead of click ing the OK butt on. 1.2. Modifying the G raphic al U ser In terface You ma y want to cust omiz e the gr aphic al user in terface by changing the w ay tha t the v arious elemen ts are ar ranged and siz ed.This c an b e achie ved b y “dragging ” elemen ts and “dropping ” them a t a new location and b y gr abbing near the edge and e xpanding or c ollapsing the selec ted elemen t. For e xample , certain it ems c an b e tabb ed on t op of other it ems , such as the gr aphics windo w on t op of the c onsole . The it ems tha t you c an mo ve include the c onsole , the task page , and the t oolbars .You c an r esize these elemen ts while the solv er is c alcula ting t o adjust the f ocus t owards y our ar ea of in terest, such as incr eas- ing the siz e of the gr aphics windo w. To restore items tha t you in tentionally or unin tentionally closed , click in the upp er-right of the Fluen t windo w, to selec t one of the pr edefined la youts and r estore missing it ems .You c an also r ight- click the t op p ortion of the Outline Vie w or Console to restore missing it ems . You ma y want to cust omiz e the gr aphic al user in terface by changing a ttribut es such as t ext color , back ground c olor , and t ext fonts.You c an c ontrol man y of these settings globally , using Preferenc es (see Setting U ser P references/Options (p.573) for mor e inf ormation). The pr ogram will tr y to pr ovide default t ext fonts tha t are sa tisfac tory for y our pla tform’s displa y siz e, but in some c ases cust omiza tion may be nec essar y if the default t ext fonts mak e the GUI t oo small or t oo lar ge on y our displa y, or if the default c olors ar e undesir able . The GUI in F luen t is based on the Qt Toolkit. If you ar e unfamiliar with the Qt Toolkit, refer to an y documen tation y ou ma y ha ve tha t descr ibes ho w to use the Qt Toolkit or applic ation. The gr aphic al attribut es c an b e mo dified in a Qt st ylesheet file named cxdisplay.qss and plac ed in y our home directory. 1.3. Setting U ser P referenc es/Options You c an sp ecify global settings tha t are applied whene ver y ou ar e op erating in ANSY S Fluen t.These settings ar e case-indep enden t and ar e controlled using the Preferenc es dialo g box. To review and mo dify y our pr eferences, open the Preferenc es dialo g box by selec ting Preferenc es... from the File menu . Tooltips ar e available when y ou ho ver o ver setting lab els tha t clar ify the pur pose/func tion of the setting . 573Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U ser P references/OptionsFile → Preferenc es... Figur e 1.17: Preferenc es D ialo g Box Note •Some settings , such as r uler visibilit y and mouse-butt on c ontrols, can also b e controlled lo cally within a F luen t session (tha t is, outside of the Preferenc es dialo g box). Settings tha t de viate from the global settings sp ecified in the Preferenc es dialo g box will not b e retained b eyond the cur rent session. •If you change a setting lo cally tha t is also c ontrolled b y Preferenc es, the lo cal change will b e shown f or this session only . If you op en the Preferenc es dialo g box and click Apply in an a ttempt to overwrite the lo cal settings change , the global setting will only app ear if it is a change fr om how the setting is alr eady sp ecified globally . For e xample , if you ha ve ANSY S Logo set as Black in Preferenc es, then y ou change the lo go t o White in the Displa y Options dialo g box, the lo go will change fr om black t o whit e. If you then r e-op en the Preferenc es dialo g box and click Apply , the lo go will r emain whit e, even though it is sp ecified as Black in the pr eferences dialo g box. The r eason b eing tha t globally , the lo go is alr eady sp ecified as black, so click ing Apply does not change the cur rent global c olor of the lo go, which is b eing o verruled b y your lo cal change t o whit e. The c ontr olling pr eferenc es file lo cation is: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 574Graphic al User In terface (GUI)•Windo ws:%HOMEDRIVE%\%HOMEPATH%\.fluentconf\19.5.0\preferences •Linux:%HOMEPATH%/.fluentconf/19.5.0/preferences If no pr eferenc e file is f ound (f or instanc e, after installation of a ne w v ersion or deletion of the pr eferenc e file), Fluent will att empt t o load user pr eferenc es fr om a pr evious v ersion. If no pr evious v ersion's pr eferenc es are found , Fluent will cr eate a ne w file using the default settings . At any time , you c an r evert your pr eferenc es t o the default settings b y click ing the Default butt on in the Prefer enc es dialo g box. Or you c an delet e the pr eferenc es file and F luent will f ollo w the ab ove rule t o cr eate a ne w one . 1.4. Fluen t Graphic al U ser In terface in J apanese You c an ha ve the F luen t graphic al user in terface app ear in Japanese b y defining the lang=ja environ- men t variable b efore launching F luen t (you c an define it in the Environmen t tab of the F luen t Launcher). Figur e 1.18: Fluen t GUI in J apanese Limita tions f or L ocaliza tion Some ar eas of the F luen t 2019 R3 GUI ar e not tr ansla ted in to Japanese including: •Drop-do wn menu/list it ems •Quick sear ch results •Pop up messages •Graphics windo w titles and lab els •Objec t names (b oundar y conditions , graphics objec ts, and so on) 575Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Fluen t Graphic al User In terface in Japanese•The Outline View tr ee in meshing mo de •Interface (GUI lab els) f or it ems without a meaning ful Japanese equiv alen t, for e xample X, Y, Z, Cp, OK, and so on 1.5. Using the H elp S ystem You c an acc ess do cumen tation, videos , and tut orials on the ANSY S Help sit e. Fluen t includes an in tegrated help sy stem tha t provides easy acc ess t o the pr ogram do cumen tation. Through the gr aphic al user in terface, you ha ve the en tire User's G uide (p.1) and other do cumen tation available t o you with the click of a mouse butt on.The F luen t User's G uide and other manuals ar e dis- played on the ANSY S help sit e, which allo ws you t o use links and sear ch t ools and inde x tools t o find the inf ormation y ou need . There ar e man y ways to acc ess ANSY S help .You c an get r eference inf ormation fr om within a task page or dialo g box, or (on Linux machines) r equest c ontext-sensitiv e help f or a par ticular task page it em or dialo g box.You c an also go t o the User's G uide (p.1) contents page and use the links t o find the in- formation y ou ar e lo oking f or. In addition t o the User's G uide (p.1), you c an also acc ess the other Fluen t do cumen tation (f or e xample , the Theor y Guide or Fluen t Customiza tion M anual ). Note tha t the last t wo chapt ers of the User's G uide ( Task P age R eference Guide (p.3235 ) and Ribbon Reference Guide (p.3745 )) (p.1) are also r eferred t o as the R eference Guide , and c ontain a descr iption of each task page , and dialo g box. The sec tions tha t follow pr ovide inf ormation on ho w to get help f or a task page or dialo g box, and brief descr iptions of the help menu it ems in F luen t. 1.5.1. Task P age and D ialog Box Help 1.5.2. Context-Sensitiv e Help (Linux Only) 1.5.3. Obtaining Lic ense U se Inf ormation 1.5.4. Version and R elease Inf ormation 1.5.1. Task P age and D ialo g Box Help To get help ab out a task page or dialo g box tha t you ar e cur rently using , click the Help butt on in the task page or dialo g box.The help will op en t o the sec tion of the User's G uide (p.1) tha t explains the func tion of each it em in the task page or dialo g box. In this sec tion, you will also find h ypertext links to mor e sp ecific sec tion(s) of the User's G uide (p.1) tha t discuss ho w to use the task page or dialo g box and pr ovide r elated inf ormation. 1.5.2. Context-Sensitiv e Help (Linux Only) If you w ant to find out ho w or when a par ticular task page it em or dialo g box is used , you c an use the c ontext-sensitiv e help f eature. Selec t the Context-Sensitiv e Help item in the help menu (acc essed by click ing ). With the r esulting question-mar k cursor , selec t an it em fr om a dr op-do wn menu .The help will op en to the sec tion of the User's G uide (p.1) tha t discusses the selec ted it em. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 576Graphic al User In terface (GUI)1.5.3. Obtaining Lic ense U se Inf ormation Your installa tion of F luen t is managed b y the ANSY S Lic ense M anager (ANSLIC_ADMIN). To lear n mor e about ANSY S lic ensing inf ormation, refer to the ANSY S, Inc. Licensing G uide . 1.5.4. Version and Release Inf ormation You c an obtain inf ormation ab out the v ersion and r elease of F luen t you ar e running b y selec ting the Version... option in help menu (acc essed b y click ing ). 577Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the H elp S ystemRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 578Chapt er 2: Text User In terface (TUI) The t ext user in terface (TUI) in F luen t, also r eferred t o as The C onsole (p.560), is wr itten in a dialec t of Lisp c alled Scheme . Users familiar with Scheme will b e able t o use the in terpretive capabilities of the interface to cr eate cust omiz ed c ommands .The t ext-based menu sy stem pr ovides a hier archic al in terface to the under lying pr ocedur al in terface of the pr ogram. •You c an easily manipula te its op eration with standar d text-based t ools—input c an b e sa ved in files , modified using t ext edit ors, and r ead back in t o be execut ed. •The t ext menu sy stem is tigh tly in tegrated with the Scheme e xtension language , so it c an easily b e programmed t o pr ovide sophistic ated c ontrol and cust omiz ed func tionalit y. A mor e complet e descr iption of the t ext-based in terface, including a full list of c ommands is a vailable in Fluen t Text Command List . 579Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 580Chapt er 3: Reading and Writing F iles During an ANSY S Fluen t session y ou ma y need t o imp ort and e xport several kinds of files . Files tha t are read include mesh, case, data, profile , Scheme , and jour nal files . Files tha t are wr itten include c ase, data, profile , jour nal, and tr anscr ipt files . ANSY S Fluen t also has f eatures tha t enable y ou t o sa ve pic tures of graphics windo ws.You c an also e xport da ta for use with v arious visualiza tion and p ostpr ocessing t ools. These op erations ar e descr ibed in the f ollowing sec tions . 3.1. Shortcuts f or R eading and Writing F iles 3.2. Reading M esh F iles 3.3. Reading and Writing C ase and D ata Files 3.4. Reading F luen t/UNS and R AMP ANT C ase and D ata Files 3.5. Reading and Writing P rofile F iles 3.6. Reading and Writing B oundar y Conditions 3.7.Writing a B oundar y Mesh 3.8. Reading Scheme S ource Files 3.9. Creating and R eading J ournal F iles 3.10. Creating Transcr ipt F iles 3.11. Imp orting F iles 3.12. Exp orting S olution D ata 3.13. Exp orting S olution D ata af ter a C alcula tion 3.14. Exp orting S teady-State Particle Hist ory Data 3.15. Exp orting D ata D uring a Transien t Calcula tion 3.16. Exp orting t o ANSY S CFD-P ost 3.17. Parallel Exp orting t o ANSY S EnS ight 3.18. Managing S olution F iles 3.19. Mesh-t o-M esh S olution In terpolation 3.20. Mapping D ata for Fluid-S tructure Interaction (FSI) A pplic ations 3.21. Saving P icture Files 3.22. Setting D ata File Q uantities 3.23. The .fluen t File 3.1. Shor tcuts f or Reading and Writing F iles The f ollowing f eatures in ANSY S Fluen t mak e reading and wr iting files c onvenien t: •Automa tic app ending or det ection of default file name suffix es •Binar y file r eading and wr iting •Automa tic det ection of file f ormat (text/binar y) •Recent file list •Reading and wr iting of c ompr essed files •Tilde e xpansion 581Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.•Automa tic numb ering of files •Abilit y to disable the o verwrite confir mation pr ompt •Standar d toolbar butt ons f or reading and wr iting files For additional inf ormation, see the f ollowing sec tions: 3.1.1. Default F ile Suffix es 3.1.2. Binar y Files 3.1.3. Detecting F ile F ormat 3.1.4. Recent File List 3.1.5. Reading and Writing C ompr essed F iles 3.1.6. Tilde Expansion (Linux S ystems Only) 3.1.7. Automa tic N umb ering of F iles 3.1.8. Disabling the O verwrite Confir mation P rompt 3.1.9. Toolbar B uttons 3.1.1. Default F ile S uffix es Each t ype of file r ead or wr itten in ANSY S Fluen t has a default file suffix asso ciated with it. When y ou specify the first par t of the file name (the pr efix) f or the c ommonly used files , Fluen t aut oma tically app ends or det ects the appr opriate suffix. For e xample , to wr ite a c ase file named myfile.cas , just specify the pr efix myfile in the Selec t File dialo g box (Figur e 3.1: The S elec t File D ialog Box (p.582)) and .cas is aut oma tically app ended . Similar ly, to read the c ase file named myfile.cas into Fluen t, you c an just sp ecify myfile and ANSY S Fluen t aut oma tically sear ches f or a file of tha t name with the suffix .cas . Figur e 3.1: The S elec t File D ialo g Box Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 582Reading and Writing F ilesThe default file suffix f or c ase and da ta files , PDF (P robabilit y Densit y Function) files , DTRM r ay files , profiles , scheme files , jour nal files , and so on, are aut oma tically det ected and app ended .The appr opriate default file suffix app ears in the Selec t File dialo g box for each t ype of file . 3.1.2. Binar y Files When y ou wr ite a c ase, data, or r ay file , a binar y file is sa ved b y default. Binar y files tak e up less memor y than t ext files and c an b e read and wr itten b y ANSY S Fluen t mor e quick ly. Note You c annot r ead and edit a binar y file , as y ou c an do f or a t ext file . To sa ve a t ext file , turn off the Write Binar y Files option in the Selec t File dialo g box when y ou ar e writing the file . Note tha t if y ou use the HDF file f ormat to wr ite out y our c ase and da ta files , the y will always be binar y (Reading and Writing F iles U sing Hier archic al D ata Format (HDF) (p.589)). 3.1.3. Detecting F ile F ormat When y ou r ead a c ase, data, mesh, PDF , or r ay file , Fluen t aut oma tically det ermines whether it is a t ext (formatted) or binar y file . 3.1.4. Rec ent File List At the b ottom of the File/Read ribbon tab submenu ther e is a list of f our ANSY S Fluen t case files tha t you most r ecently r ead or wr ote.To read one of these files in to ANSY S Fluen t, selec t it in the list. This allows you t o read a r ecently used file without selec ting it in the Selec t File dialo g box. If you w ant to change the numb er of r ecent files list ed, you c an change the Numb er of files r ecently used setting in the Preferenc es dialo g box, which y ou c an acc ess b y selec ting Preferenc es... from the File ribbon tab. Note tha t the files list ed in this submenu ma y not b e appr opriate for y our cur rent session (f or e xample , a 3D c ase file c an b e list ed e ven if y ou ar e running a 2D v ersion of ANSY S Fluen t). Also, if y ou r ead a case file using this shor tcut, the c orresponding da ta file is r ead only if it has the same base name as the c ase file (f or e xample ,file1.cas and file1.dat ) and it w as read/wr itten with the c ase file the last time the c ase file w as read/wr itten. 3.1.5. Reading and Writing C ompr essed F iles For mor e inf ormation, see the f ollowing sec tions: 3.1.5.1. Reading C ompr essed F iles 3.1.5.2. Writing C ompr essed F iles 3.1.5.1. Reading C ompr essed F iles You c an use the Selec t File dialo g box to read files c ompr essed using compress or gzip . If you selec t a c ompr essed file with a .Z extension, ANSY S Fluen t aut oma tically op ens zcat to imp ort the file. If you selec t a c ompr essed file with a .gz extension, Fluen t op ens gunzip to imp ort the file . 583Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Shortcuts f or R eading and Writing F ilesFor e xample , if y ou selec t a file named flow.msh.gz , Fluen t reports the f ollowing message indic ating that the r esult of the gunzip is imp orted in to ANSY S Fluen t via an op erating sy stem pip e. Reading "\"| gunzip -c \"Y:\flow.msh.gz\"\""... You c an also t ype in the file name without an y suffix (f or e xample , if y ou ar e not sur e whether or not the file is c ompr essed). First, Fluen t attempts t o op en a file with the input name . If it c annot find a file with tha t name , it a ttempts t o lo cate files with default suffix es and e xtensions app ended t o the name . For e xample , if y ou en ter the name file-name , Fluen t traverses the f ollowing list un til it finds an existing file: •file-name •file-name.gz •file-name.Z •file-name. suffix •file-name. suffix.gz •file-name. suffix.Z wher e suffix is a c ommon e xtension t o the file , such as .cas or .msh . Fluen t reports an er ror if it fails t o find an e xisting file with one of these names . Note In addition t o .gz and .Z compr ession, ANSY S Fluen t can also handle .bz2 compr essed files . Imp ortant •For Windo ws systems , only files tha t were compr essed with gzip (tha t is, files with a .gz ex- tension) c an b e read. Files tha t were compr essed with compress cannot b e read in to ANSY S Fluen t on a Windo ws machine . •Do not r ead a c ompr essed r ay file; ANSY S Fluen t cannot acc ess the r ay tracing inf ormation properly from a c ompr essed r ay file . 3.1.5.2. Writing C ompr essed F iles You c an use the Selec t File dialo g box to wr ite a c ompr essed file b y app ending a .Z or .gz extension onto the file name . For e xample , if y ou en ter flow.gz as the name f or a c ase file , Fluen t reports the f ollowing message: Writing "| gzip -cfv > Y:\flow.cas.gz"... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 584Reading and Writing F ilesThe sta tus message indic ates tha t the c ase file inf ormation is b eing pip ed in to the gzip command , and tha t the output of the c ompr ession c ommand is b eing r edir ected t o the file with the sp ecified name . In this par ticular e xample , the .cas extension is added aut oma tically. Note In addition t o .gz and .Z compr ession, ANSY S Fluen t can also handle .bz2 compr essed files . Imp ortant •For Windo ws systems , compr ession c an b e performed only with gzip .That is, you c an wr ite a compr essed file b y app ending .gz to the name , but app ending .Z does not c ompr ess the file. •Do not wr ite a c ompr essed r ay file; ANSY S Fluen t cannot acc ess the r ay tracing inf ormation properly from a c ompr essed r ay file . 3.1.6. Tilde E xpansion (Linux S ystems Only) On Linux sy stems , if y ou sp ecify ~/ as the first t wo char acters of a file name , the ~ is e xpanded as your home dir ectory. Similar ly, you c an star t a file name with ~username/ , and the ~username is expanded t o the home dir ectory of “user name ”. If you sp ecify ~/file as the c ase file t o be wr itten, ANSY S Fluen t saves the file file.cas in y our home dir ectory.You c an sp ecify a sub directory of y our home dir ectory as w ell: if y ou en ter ~/cases/file.cas , ANSY S Fluen t saves the file file.cas in the cases sub directory. 3.1.7. Automa tic N umb ering of F iles There ar e se veral sp ecial char acters tha t you c an include in a file name . Using one of these char acter strings in y our file name pr ovides a shor tcut f or numb ering the files based on v arious par amet ers (tha t is, iteration numb er, time st ep, or t otal numb er of files sa ved so far), because y ou need not en ter a new file name each time y ou sa ve a file . (See also Automa tic S aving of C ase and D ata Files (p.591) for information ab out sa ving and numb ering c ase and da ta files aut oma tically.) •For tr ansien t calcula tions , you c an sa ve files with names tha t reflec t the time st ep a t which the y are sa ved by including the char acter str ing %t in the file name . For e xample , you c an sp ecify contours-%t.ps for the file name , and F luen t saves a file with the appr opriate name (f or e xample ,contours-0001.ps if the solution is a t the first time st ep). This aut oma tic sa ving of files with the time st ep should not b e used f or st eady-sta te cases , sinc e the time st ep will alw ays remain z ero. •For tr ansien t calcula tions , you c an sa ve files with names tha t reflec t the flo w-time a t which the y are sa ved by including the char acter str ing %f in the file name .The usage is similar t o %t. For e xample , when y ou specify filename-%f.ps for the file name , Fluen t will sa ve a file with the appr opriate name (f or e xample , filename-005.000000.ps for a solution a t a flo w-time of 5 sec onds). By default , the flo w-time tha t is included in the file name will ha ve a field width of 10 and 6 decimal plac es.To mo dify this f ormat, use the char acter str ing %x.yf, wher e x and y are the pr eferred field width and numb er of decimal plac es, respectively. ANSY S Fluen t will aut oma tically add z eros to the b eginning of the flo w-time t o achie ve the 585Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Shortcuts f or R eading and Writing F ilesprescr ibed field width. To elimina te these z eros and lef t align the flo w-time , use the char acter str ing %- x .yf inst ead. This aut oma tic sa ving of files with flo w-time should not b e used f or st eady-sta te cases , sinc e the flow-time will alw ays remain z ero. •To sa ve a file with a name tha t reflec ts the it eration a t which it is sa ved, use the char acter str ing %i in the file name . For e xample , you c an sp ecify contours-%i.ps for the file name , and F luen t saves a file with the appr opriate name (f or e xample ,contours-0010.ps if the solution is a t the 10th it eration). •To sa ve a pic ture file with a name tha t reflec ts the t otal numb er of pic ture files sa ved so far in the cur rent Fluen t session, use the char acter str ing %n in the file name .This option c an b e used only f or pic ture files . The default field width f or %i,%t, and %n formats is 4. You c an change the field width b y using %x i,%xt, and %xn in the file name , wher e x is the pr eferred field width. 3.1.8. Disabling the O verwrite Confir mation P rompt By default , if y ou ask ANSY S Fluen t to wr ite a file with the same name as an e xisting file in tha t folder , it will ask y ou t o confir m tha t it is “OK t o overwrite” the e xisting file . If you do not w ant Fluen t to ask you f or c onfir mation b efore it o verwrites e xisting files , you c an use the Batch Options dialo g box (see Batch Ex ecution Options (p.57) in the Getting S tarted G uide for details). Alternatively, enter the file/confirm-overwrite? text command and answ er no (see Text User In terface (TUI) (p.579) for the t ext user in terface commands). 3.1.9. Toolbar Butt ons The standar d toolbar pr ovides butt ons tha t mak e it easier t o read and wr ite files: •The Read a file butt on ( ) allo ws you t o read e xisting files using a file selec tion dialo g box.The files available f or reading include all those a vailable thr ough the File/Read ribbon tab it em, as descr ibed in this chapt er. •The Write a file butt on ( ) allo ws you t o wr ite various t ypes of files .The files a vailable f or wr iting include all those a vailable thr ough the File/W rite ribbon tab it em, as descr ibed in this chapt er. 3.2. Reading M esh F iles Mesh files ar e created using the mesh gener ators (ANSY S M eshing , the meshing mo de of F luen t, Fluen t Meshing , GAMBIT , GeoM esh, and P reBFC), or b y se veral thir d-par ty CAD pack ages . From the p oint of view of ANSY S Fluen t, a mesh file is a subset of a c ase file (descr ibed in Reading and Writing C ase Files (p.588)).The mesh file c ontains the c oordina tes of all the no des, connec tivit y inf ormation tha t tells how the no des ar e connec ted t o one another t o form fac es and c ells, and the z one t ypes and numb ers of all the fac es (f or e xample , wall-1, pressur e-inlet-5, symmetr y-2). The mesh file do es not c ontain an y inf ormation on b oundar y conditions , flow par amet ers. For inf ormation about meshes , see Reading and M anipula ting M eshes (p.703). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 586Reading and Writing F ilesTo read a na tive-format mesh file (tha t is, a mesh file tha t is sa ved in the ANSY S Fluen t format, which includes FL UENT 5/6, Fluen t/UNS, or R AMP ANT meshes) in to Fluen t, use the File/Read/M esh... ribbon tab it em. File → Read → Mesh... Note tha t you c an also use the File/Read/C ase... ribbon tab it em (descr ibed in Reading and Writing Case F iles (p.588)), because a mesh file is a subset of a c ase file . ANSY S M eshing , the meshing mo de of Fluen t, Fluen t Meshing , GAMBIT , GeoM esh, and P reBFC c an all wr ite a na tive-format mesh file . For in- formation ab out these files and ho w the y are created, see ANSY S M eshing M esh F iles (p.724),Fluen t Meshing M ode M esh F iles (p.724),Fluen t Meshing M esh F iles (p.724),GAMBIT M esh F iles (p.724),Geo- Mesh M esh F iles (p.724), and PreBFC M esh F iles (p.725). If after reading in a mesh file (or a c ase and da ta file), you w ould lik e to read in another mesh file , the Read M esh Options D ialog Box (p.3746 ) will op en, wher e you c an cho ose t o •Discard the c ase and r ead in a new mesh. •Replac e the e xisting mesh. You also ha ve the option t o ha ve the Scale M esh dialo g box app ear aut oma tically f or y ou t o check or scale y our mesh, which in gener al is the r ecommended pr actice. For this t o happ en, enable Show Sc ale Mesh P anel A fter Replacing M esh. For inf ormation on imp orting an unpar titioned mesh file in to the par allel v ersion of F luen t using the partition filt er, see Using the P artition F ilter (p.3089 ). For inf ormation ab out r eading sur face mesh files , see Reading Sur face M esh F iles (p.737). 3.3. Reading and Writing C ase and D ata F iles Information r elated t o the ANSY S Fluen t simula tion is st ored in b oth the c ase file and the da ta file .The commands f or reading and wr iting these files ar e descr ibed in the f ollowing sec tions , along with c om- mands f or the aut oma tic sa ving of c ase and da ta a t sp ecified in tervals. ANSY S Fluen t can r ead and wr ite either t ext or binar y case and da ta files . Binar y files r equir e less st orage spac e and ar e fast er to read and wr ite. By default , ANSY S Fluen t wr ites files in binar y format.To wr ite a text file , disable the Write Binar y Files check butt on in the Selec t File dialo g box. In addition, you can r ead and wr ite either t ext or binar y files in c ompr essed f ormats (F or details , see Reading and Writing Compr essed F iles (p.583)). ANSY S Fluen t aut oma tically det ects the file t ype when r eading . Further mor e, when wr iting c ase and da ta files , ANSY S Fluen t can impr ove I/O p erformanc e using asynchr onous file c ompr ession which c an b e enabled using the Optimiz e Using A synchr onous I/O check butt on in the Selec t File dialo g box. This option is par ticular ly beneficial if y ou w ant to impr ove the o verall p erformanc e of simula tions in- volving solution check-p ointing . Performanc e is impr oved b y overlapping the file c ompr ession and file system c opy op erations with subsequen t iterations or other op erations . It is b est if the fr ont end C ortex 587Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Reading and Writing C ase and D ata Filesprocess has its o wn dedic ated pr ocessor c ore (or machine) not used b y the ANSY S Fluen t comput e- node pr ocesses , even though the option w ould aid p erformanc e even if the y reside on the same machine . Imp ortant •The Optimiz e Using A synchr onous I/O option is not a vailable on Windo ws machines . •If you adapt the mesh, you must sa ve a new c ase file as w ell as a da ta file . Other wise , the new data file will not c orrespond t o the c ase file (f or e xample , the y will ha ve diff erent numb ers of cells). If you ha ve not sa ved the la test c ase or da ta file , ANSY S Fluen t will w arn you when y ou tr y to exit the pr ogram. For additional inf ormation, see the f ollowing sec tions: 3.3.1. Reading and Writing C ase F iles 3.3.2. Reading and Writing D ata Files 3.3.3. Reading and Writing C ase and D ata Files Together 3.3.4. Reading and Writing F iles U sing Hier archic al D ata Format (HDF) 3.3.5. Automa tic S aving of C ase and D ata Files 3.3.1. Reading and Writing C ase F iles Case files c ontain the mesh, boundar y and c ell z one c onditions , and solution par amet ers f or a pr oblem. It also c ontains the inf ormation ab out the user in terface and gr aphics en vironmen t. For inf ormation about the f ormat of c ase files see Case and D ata File F ormats (p.3969 ).The c ommands used f or reading case files c an also b e used t o read na tive-format mesh files (as descr ibed in Reading M esh F iles (p.586)) because the mesh inf ormation is a subset of the c ase inf ormation. Selec t the File/Read/C ase... ribbon tab it em t o op en the Selec t File dialo g box. File → Read → Case... Read a c ase file using the Selec t File dialo g box. Note tha t the Displa y M esh A fter Reading option in the Selec t File dialo g box allo ws you t o ha ve the mesh displa yed aut oma tically af ter it is r ead. Selec t the File/W rite/Case... ribbon tab it em t o op en the Selec t File dialo g box. File → Write → Case... Write a c ase file using the Selec t File dialo g box. When ANSY S Fluen t reads a c ase file , it first lo oks f or a file with the e xact name y ou t yped. If a file with that name is not f ound , it sear ches f or the same file with diff erent extensions ( Reading and Writing Compr essed F iles (p.583)).When ANSY S Fluen t wr ites a c ase file ,.cas is added t o the name y ou t ype unless the name alr eady ends with .cas . In the single-pr ecision v ersion of ANSY S Fluen t, nodal c oordina tes ar e wr itten b y default in double precision, in or der t o ensur e tha t ther e is no loss of pr ecision if the c ase file is r ead back in to the meshing mo de.You c an r educ e the pr ecision and c ase file siz e by using the f ollowing t ext command prior t o wr iting: file → single-precision-coordinates? Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 588Reading and Writing F iles3.3.2. Reading and Writing D ata F iles Data files c ontain the v alues of the sp ecified flo w field quan tities in each mesh elemen t and the c on- vergenc e hist ory (residuals) f or tha t flo w field . For inf ormation ab out the f ormat of da ta files see Case and D ata File F ormats (p.3969 ). 1.After reading a mesh or c ase file , selec t the File/Read/D ata... ribbon tab it em t o op en the Selec t File dialo g box. File → Read → Data... 2.Read a da ta file using the Selec t File dialo g box. 3.After gener ating da ta for a c ase file , selec t the File/W rite/D ata... ribbon tab it em t o op en the Selec t File dialo g box. File → Write → Data... 4.Write a da ta file using the Selec t File dialo g box. When ANSY S Fluen t reads a da ta file , it first lo oks f or a file with the e xact name y ou t yped. If a file with tha t name is not f ound , it sear ches f or the same file with diff erent extensions ( Reading and Writing C ompr essed F iles (p.583)).When ANSY S Fluen t wr ites a da ta file ,.dat is added t o the name you t ype unless the name alr eady ends with .dat . You c an output additional quan tities f or p ost-pr ocessing in other applic ations using the D ata File Quan tities dialo g box (see Setting D ata File Q uan tities (p.651)). 3.3.3. Reading and Writing C ase and D ata F iles Together A case file and a da ta file t ogether c ontain all the inf ormation r equir ed t o restar t a solution. Case files contain the mesh, boundar y and c ell z one c onditions , and solution par amet ers. Data files c ontain the values of the flo w field in each mesh elemen t and the c onvergenc e hist ory (residuals) f or tha t flo w field . You c an r ead a c ase file and a da ta file t ogether b y using the Selec t File dialo g box op ened b y selec ting the File/Read/C ase & D ata... ribbon tab it em. To read b oth files , selec t the appr opriate case file , and the c orresponding da ta file (same name with .dat suffix) is also r ead. Note tha t the Displa y M esh After Reading option in the Selec t File dialo g box allo ws you t o ha ve the mesh displa yed aut oma tically after it is r ead. File → Read → Case & D ata... To wr ite a c ase file and a da ta file , selec t the File/W rite/Case & D ata... ribbon tab it em. File → Write → Case & D ata... 3.3.4. Reading and Writing F iles U sing Hier archic al D ata F ormat (HDF) When r eading and wr iting c ase and da ta files in ser ial or par allel, you c an optionally use the Hier arch- ical D ata Format (HDF). To read or wr ite case/da ta files using HDF , you c an use the same GUI or TUI commands as y ou nor mally w ould and simply app end .h5 to the file name . Alternatively, you c an 589Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Reading and Writing C ase and D ata Filesselec t HDF5 C ase F iles or HDF5 D ata F iles from the Files of t ype drop-do wn list in the Selec t File dialo g box. If you w ant to wr ite HDF files aut oma tically a t sp ecified in tervals dur ing a c alcula tion, do not app end .h5 to the file name in the Autosave Dialog Box (p.3628 ), but inst ead set HDF as the default for reading and wr iting files b y using the f ollowing t ext command: file → hdf-files? Note HDF files ar e not supp orted in F luen t Meshing or when r unning F luen t under ANSY S Workbench. HDF files ar e alw ays binar y and mak e use of built-in c ompr ession. Thus, the y cannot b e view ed in a text edit or. However, thir d-par ty tools ar e available tha t allo w you t o op en and e xplor e the c ontents of files sa ved in HDF f ormat. You c an sp ecify the I/O mo de and/or the HDF c ompr ession le vel thr ough t ext commands: > file hdfio-options compression-level compression-level [0-9]? [1] 4 > file hdfio-options io-mode HDF5 I/O Modes: 1. HOST 2. NODE0 3. PARALLEL INDEPENDENT 4. PARALLEL COLLECTIVE Enter Mode Number: [2] 1 HOST mode selected. The c ompr ession le vel can b e set fr om 0 (no c ompr ession; fast est) t o 9 (maximum c ompr ession; slowest); the default le vel is 1. Note tha t incr easing the c ompr ession le vel ma y not nec essar ily yield a corresponding decr ease in file siz e. The a vailable I/O mo des ar e: HOST : I/O is done ser ially b y the host pr ocess.This is the default mo de when the file pa th is not acc essible t o comput e-no de 0. NODE0 : I/O is done ser ially b y the no de 0 pr ocess.This is the default mo de when the file pa th is acc essible t o comput e-no de 0. PARALLEL INDEPENDENT : I/O is done in a par allel file sy stem using the indep enden t mo de of MPI I/O . PARALLEL C OLLECTIVE : I/O is done in a par allel file sy stem using the c ollec tive mo de of MPI I/O. Note •The P arallel I/O mo des do not supp ort compr ession. If you ha ve sp ecified a non-z ero level for compr ession and y ou swit ch to one of the par allel mo des, the c ompr ession will b e set t o 0. When using the double-pr ecision solv er, you c an sp ecify tha t the da ta wr itten in HDF da ta files is single precision (and thus sacr ifice some pr ecision in or der t o reduc e the siz e of the files) b y using the f ollowing text command pr ior t o wr iting: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 590Reading and Writing F ilesfile → hdfio-options → single-precision-data? 3.3.5. Automa tic S aving of C ase and D ata F iles You c an r equest ANSY S Fluen t to aut oma tically sa ve case and da ta files a t sp ecified in tervals dur ing a calcula tion. This is esp ecially useful f or time-dep enden t calcula tions , sinc e it allo ws you t o sa ve the results a t diff erent time st eps, flow times , or cr ank angles (f or in-c ylinder simula tions) without st opping the c alcula tion and p erforming the sa ve manually .You c an also use the aut osave feature for st eady- state pr oblems , and thus e xamine the solution a t diff erent stages in the it eration hist ory. Automa tic sa ving is sp ecified using the Autosave Dialog Box (p.3628 ) (Figur e 3.2: The A utosave Dialog Box (p.591)), which is op ened b y click ing the Edit... butt on ne xt to the Autosa ve Every text box in the Calcula tion A ctivities task page . Calcula tion A ctivities Figur e 3.2: The A utosa ve D ialo g Box Specify ho w of ten y ou w ould lik e to sa ve your mo dified files b y en tering the fr equenc y in the Save Data F ile E very numb er-en try field .Save D ata F ile E very is set t o zero by default , indic ating tha t no automa tic sa ving is p erformed . For tr ansien t in-c ylinder simula tions , specify whether y ou w ant to sa ve the da ta b y Time S teps or Crank A ngles . If you cho ose t o sa ve the c ase file only if it is mo dified , then selec t Only if mo dified under Save As- sociated C ase F iles. Note tha t the c ase file will b e sa ved whether y ou mak e a manual change , or if 591Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Reading and Writing C ase and D ata FilesANSY S Fluen t mak es a change in ternally dur ing the c alcula tion. If you cho ose t o sa ve the c ase file every time the da ta file is sa ved, then selec t Each Time . Imp ortant To sa ve only the da ta files , use the f ollowing TUI option: file → auto-save → case-frequency → if-mesh-is-modified This will r esult in the options in the Save Associated C ase F iles group b ox being disabled in the Autosa ve dialo g box. In essenc e, this TUI c ommand f orces ANSY S Fluen t to the sa ve case file only when the mesh is mo dified . It do es not disable c ase file sa ving , but r educ es it to an absolut e minimum. This is nec essar y to do so sinc e you c annot r ead a da ta file without a c ase file c ontaining a ma tching mesh. For st eady-sta te solutions , specify the fr equenc y in it erations . For tr ansien t solutions , specify it in time steps (unless y ou ar e using the e xplicit time st epping f ormula tion, in which c ase sp ecify the fr equenc y in it erations). For tr ansien t in-c ylinder solutions , you c an cho ose t o sp ecify the fr equenc y in cr ank angles . If you define a fr equenc y of 5, for e xample , a case file is sa ved e very 5 it erations , time st eps, or cr ank angles . If you ha ve limit ed disk spac e, restrict the numb er of files sa ved b y ANSY S Fluen t by selec ting the Retain Only the M ost Rec ent Files option. When selec ted, enter the Maximum N umb er of D ata F iles you would lik e to retain. Note tha t the c ase and da ta files ar e treated separ ately with r egar d to the maximum numb er of files sa ved when o verwriting . For e xample , if the v alue of Maximum N umb er of D ata F iles is set t o fiv e, ANSY S Fluen t saves a maximum of fiv e case and fiv e da ta files , irrespective of the fr equenc y. After the maximum limit of files has b een sa ved, ANSY S Fluen t begins o verwriting the ear liest e xisting file. Note When the Retain only the M ost Rec ent Files option is selec ted, the solution hist ory cur rently in memor y will b e disc arded and the solution hist ory reset. If you ha ve gener ated da ta (either b y initializing the solution or r unning the c alcula tion) y ou c an view the list of standar d quan tities tha t will b e wr itten t o the da ta file as a r esult of the aut osave, and e ven selec t additional quan tities f or p ostpr ocessing in alt ernative applic ations . Click the Data F ile Q uan tities ... butt on t o op en the Data F ile Q uan tities dialo g box, and mak e an y nec essar y selec tions . For details , see Setting D ata File Q uan tities (p.651). Enter a r oot name f or the aut osave files in the File N ame text box.When the files ar e sa ved, a numb er will b e app ended t o this r oot name t o indic ate the p oint at which it w as sa ved dur ing the c alcula tion: for st eady-sta te solutions , this will b e the it eration numb er, wher eas f or tr ansien t solutions it will b e either the time st ep numb er, flow time , or cr ank angle (dep ending on y our selec tion in the st ep tha t follows). An extension will also b e aut oma tically added t o the r oot name (.cas or .dat ). If the sp ecified File N ame ends in .gz or .Z, appr opriate file c ompr ession is p erformed . For details ab out file c om- pression, see Reading and Writing C ompr essed F iles (p.583). For details on aut osaving files in the hier archic al da ta format (HDF), see Reading and Writing F iles U sing Hier archic al D ata Format (HDF) (p.589). For tr ansien t calcula tions , mak e a selec tion fr om the Append F ile N ame with drop-do wn list t o indic ate whether y ou w ant the r oot file name t o be app ended with the time-st ep,flow-time or crank-angle Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 592Reading and Writing F iles(see Figur e 3.2: The A utosave Dialog Box (p.591)). If you selec t either of the la tter two, you c an set the Decimal P laces in F ile N ame to det ermine the ultima te width of the file name . Consider a tr ansien t case f or which y ou w ant to sa ve your c ase and da ta files a t known time st eps. The pr ocedur e you w ould f ollow is t o first set the fr equenc y in the Save D ata F ile E very text box. Selec t Each Time if y ou w ant both c ase and da ta files sa ved a t the same in terval.Then en ter my_file for the File N ame . Finally , selec t time-st ep from the Append F ile N ame with drop-do wn list. An ex- ample of the r esulting files sa ved w ould b e my_file-0005.cas my_file-0005.dat indic ating tha t these files w ere sa ved a t the fif th time st ep. You c an r evise the instr uctions f or the pr evious e xample t o inst ead sa ve case and da ta files a t known flow times , by selec ting flow-time from the Append F ile N ame with drop-do wn list. The default Decimal P laces in F ile N ame will b e six. An example of the r esulting files sa ved w ould b e my_file-0.500000.cas my_file-0.500000.dat indic ating tha t these files w ere sa ved a t a flo w time of 0.5 sec onds . For st eady-sta te and tr ansien t cases , you ha ve the option of aut oma tically numb ering the files (as de- scribed in Automa tic N umb ering of F iles (p.585)), and ther eby include fur ther inf ormation ab out when the files w ere sa ved.This in volves the addition of sp ecial char acters t o the File N ame . For e xample , you ma y want the file names t o convey the flo w times with their c orresponding time st eps (tr ansien t cases only). Selec t time-st ep from the Append F ile N ame with , and en ter a File N ame tha t ends with -%f to aut oma tically numb er the files with the flo w time .Thus, entering a File N ame of filename- %f could r esult in a sa ved c ase file named filename-000.500000-0010.cas .The c onventions used in this e xample c an b e explained as f ollows: •filename- is the file name y ou en tered when aut osaving y our solution. •000.500000 is the r esult of the sp ecial char acter %f added t o the file name , and is the flo w time .This flow time has a field width of t en char acters, which allo ws for six decimal plac es (as discussed in Automa tic Numb ering of F iles (p.585)). •-0010 is the app ended time-st ep, as designa ted b y the selec tion in the Append F ile N ame with drop- down list. •.cas is the file e xtension aut oma tically added when using the aut osave option. All of the aut osave inputs ar e stored in memor y when y ou click OK in the Autosa ve dialo g box, and can then b e sa ved with the c ase file . 3.4. Reading F luen t/UNS and R AMP ANT C ase and D ata F iles Case files cr eated b y Fluen t/UNS 3 or 4 or R AMP ANT 2, 3, or 4 c an b e read in to ANSY S Fluen t in the same w ay tha t cur rent case files ar e read (see Reading and Writing C ase and D ata Files (p.587)). If you read a c ase file cr eated b y Fluen t/UNS, ANSY S Fluen t selec ts Pressur e-Based in the Solver group b ox of the Gener al Task P age (p.3235 ). If you r ead a c ase file cr eated b y RAMP ANT , ANSY S Fluen t selec ts 593Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Reading F luen t/UNS and R AMP ANT C ase and D ata FilesDensit y-Based in the Solver group b ox of the Gener al Task P age (p.3235 ), as w ell as Explicit from the Formula tion drop-do wn menu in the Solution M etho ds Task P age (p.3603 ). Data files cr eated b y Fluen t/UNS 4 or R AMP ANT 4 c an b e read in to ANSY S Fluen t in the same w ay tha t current da ta files ar e read (see Reading and Writing C ase and D ata Files (p.587)). 3.5. Reading and Writing P rofile F iles Boundar y pr ofiles ar e used t o sp ecify flo w conditions on a b oundar y zone of the solution domain. For example , the y can b e used t o pr escr ibe a v elocity field on an inlet plane . For inf ormation on b oundar y profiles , see Profiles (p.1051 ). For inf ormation ab out tr ansien t profiles , see Defining Transien t Cell Z one and B oundar y Conditions (p.1066 ). For additional inf ormation, see the f ollowing sec tions: 3.5.1. Reading P rofile F iles 3.5.2. Writing P rofile F iles 3.5.1. Reading P rofile F iles To read the b oundar y pr ofile files , open the Selec t File dialo g box by selec ting the File/Read/P rofile ... ribbon tab it em. File → Read → Profile ... This op ens the Selec t File dialo g box so tha t you c an r ead a b oundar y pr ofile with the standar d exten- sion .prof or a tr ansien t profile in tabular f ormat with the standar d extension .ttab . If a pr ofile in the file has the same name as an e xisting pr ofile , the old pr ofile will b e overwritten. Note The maximum numb er of pr ofiles tha t can b e read in to a single F luen t session is 50. 3.5.2. Writing P rofile F iles You c an also cr eate a pr ofile file fr om the c onditions on a sp ecified b oundar y or sur face. For e xample , you c an cr eate a pr ofile file fr om the outlet c onditions of one c ase.Then y ou c an r ead tha t profile in to another c ase and use the outlet pr ofile da ta as the inlet c onditions f or the new c ase. To wr ite a pr ofile file , use the Write Profile D ialog Box (p.3478 ) (Figur e 3.3: The Write Profile D ialog Box (p.595)). File → Write → Profile ... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 594Reading and Writing F ilesFigur e 3.3: The Write Profile D ialo g Box 1.Retain the default option of Define N ew P rofiles . 2.Selec t the sur face(s) fr om which y ou w ant to extract da ta for the pr ofile(s) in the Surfaces list. 3.Choose the v ariable(s) f or which y ou w ant to create pr ofiles in the Values list. 4.Optionally selec t Write M erge P rofiles .This wr ites a .csv file with the selec ted sur faces c onsolida ted into one set of da ta p oints. Note tha t this option is only a vailable if y ou ha ve selec ted 2 or mor e sur faces. 5.Click Write... and sp ecify the pr ofile file name in the r esulting Selec t File dialo g box. ANSY S Fluen t saves the mesh c oordina tes of the da ta p oints for the selec ted sur face(s) and the values of the selec ted v ariables a t those p ositions .When y ou r ead the pr ofile file back in to Fluen t, you c an selec t the pr ofile v alues fr om the r elevant drop-do wn lists in the b oundar y condition dialo g boxes.The names of the pr ofile v alues in the dr op-do wn lists will c onsist of the sur face name and the par ticular v ariable . 6.Selec t the Write Currently D efined P rofiles option: •if you ha ve made an y mo dific ations t o the b oundar y pr ofiles sinc e you r ead them in (f or e xample , if you r eoriented an e xisting pr ofile t o create a new one). •if you w ant to store all the pr ofiles used in a c ase file in a separ ate file . 595Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Reading and Writing P rofile F iles7.Click Write... and sp ecify the file name in the r esulting Selec t File dialo g box. All cur rently defined pr ofiles are sa ved in this file .This file c an b e read back in to Fluen t whene ver you w ant to use these pr ofiles again. 3.6. Reading and Writing B oundar y Conditions To sa ve all cur rently defined b oundar y conditions t o a file , enter the file/write-settings text command and sp ecify a name f or the file . file → write-settings ANSY S Fluen t wr ites the b oundar y and c ell z one c onditions , the solv er, and mo del settings t o a file using the same f ormat as the “zone” sec tion of the c ase file . See Case and D ata File F ormats (p.3969 ) for details about the c ase file f ormat. To read b oundar y conditions fr om a file and t o apply them t o the c orresponding z ones in y our mo del, enter the file/read-settings text command . file → read-settings ANSY S Fluen t sets the b oundar y and c ell z one c onditions in the cur rent mo del b y compar ing the z one name asso ciated with each set of c onditions in the file with the z one names in the mo del. If the mo del does not c ontain a ma tching z one name f or a set of b oundar y conditions , those c onditions ar e ignor ed. If you r ead b oundar y conditions in to a mo del tha t contains a diff erent mesh t opology (for e xample , a cell z one has b een r emo ved), check the c onditions a t boundar ies within and adjac ent to the r egion of the t opological change .This is imp ortant for w all z ones . Note If the b oundar y conditions ar e not check ed and some r emain uninitializ ed, the c ase will not run succ essfully . When the file/read-settings text command is not used , all b oundar y conditions get the default settings when a mesh file is imp orted, allo wing the c ase t o run with the default v alues . If you w ant ANSY S Fluen t to apply a set of c onditions t o multiple z ones with similar names , or t o a single z one with a name y ou ar e not sur e of in ad vance, you c an edit the b oundar y-condition file sa ved with the file/write-settings command t o include wildc ards (*) within the z one names . For e x- ample , if y ou w ant to apply a par ticular set of c onditions t o wall-12 ,wall-15 , and wall-17 in y our cur rent model, edit the b oundar y-condition file so tha t the z one name asso ciated with the desir ed c onditions is wall-* . Note The settings file c ontains only y our user-mo dified settings and do es not include default ANSY S Fluen t par amet ers.The default par amet ers ma y be up dated with each new r elease . Consequen tly, the usage of the same settings file in diff erent releases of ANSY S Fluen t does not guar antee the same setup , which c an c ause solution diff erences. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 596Reading and Writing F iles3.7. Writing a B oundar y M esh You c an wr ite the b oundar y zones (sur face mesh) t o a file .This file c an b e read and used b y the meshing mo de of F luen t to pr oduce a v olume mesh. You ma y find this f eature useful if y ou ar e unsa t- isfied with a mesh obtained fr om another mesh gener ation pr ogram. A boundar y mesh c an b e wr itten using the Selec t File dialo g box, opened b y selec ting the File/W rite/Boundar y M esh... ribbon tab it em. File → Write → Boundar y M esh... 3.8. Reading Scheme S our ce Files A Scheme sour ce file c an b e loaded in thr ee w ays: through the menu sy stem as a scheme file , through the menu sy stem as a jour nal file , or thr ough Scheme itself . For lar ge sour ce files , use the Selec t File dialo g box, opened b y selec ting the File/Read/Scheme ... ribbon tab it em File → Read → Scheme ... or use the Scheme load func tion in the c onsole , as sho wn in the f ollowing e xample: > (load "file.scm") Shorter files c an also b e loaded with the File/Read/J our nal... ribbon tab it em or the file/read- journal command in the t ext interface (or its . or source alias , as sho wn in the e xample tha t follows). >. file.scm > source file.scm In this c ase, each char acter of the file is echo ed t o the c onsole as it is r ead, in the same w ay as if y ou were typing in the c ontents of the file . 3.9. Creating and Reading J our nal F iles A jour nal file c ontains a sequenc e of ANSY S Fluen t commands , arranged as the y would b e typed in ter- actively in to the pr ogram or en tered thr ough the GUI or TUI. The GUI and TUI c ommands ar e recorded as Scheme c ode lines in jour nal files .You c an also cr eate jour nal files manually with a t ext edit or. If you want to include c ommen ts in y our file , be sur e to put a semic olon (;) at the b eginning of each c ommen t line. See Background Ex ecution on Linux S ystems (p.55) in the Getting S tarted G uide for an e xample . The pur pose of a jour nal file is t o aut oma te a ser ies of c ommands inst ead of en tering them r epeatedly on the c ommand line . Another use is t o pr oduce a r ecord of the input t o a pr ogram session f or la ter reference, although tr anscr ipt files ar e of ten mor e useful f or this pur pose. (For details , see Creating Transcr ipt F iles (p.601)). 597Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Creating and R eading J ournal F ilesCommand input is tak en fr om the sp ecified jour nal file un til its end is r eached , at which time c ontrol is retur ned t o the standar d input (usually the k eyboard). Each line fr om the jour nal file is echo ed t o the standar d output (usually the scr een) as it is r ead and pr ocessed . Imp ortant •A jour nal file is , by design, just a simple r ecord and pla yback facilit y. It contains no inf ormation about the sta te in which it w as recorded (other than the v ersion of ANSY S Fluen t tha t it w as created in) or the sta te in which it is b eing pla yed back. •The pr ecision (single or double) tha t the jour nal is r ecorded in ma y aff ect pla yback when it is read in to a session tha t is r unning in the other pr ecision. •Be careful not t o change the f older while r ecording a jour nal file . Also, try to re-cr eate the sta te in which the jour nal w as wr itten b efore you r ead it in to the pr ogram. For e xample , if your jour nal file includes an instr uction to sa ve a new file with a sp ecified name , you should check tha t if a file with tha t name e xists in y our f older before you r ead in y our jour nal file . If a file with tha t name e xists and y ou r ead in y our jour nal file , when the program r eaches the wr ite instr uction, it will pr ompt f or a c onfir mation t o overwrite the old file . Since the jour nal file do es not c ontain an y response t o the c onfir mation r equest , ANSY S Fluen t cannot continue t o follow the instr uctions of the jour nal file . •Other c onditions tha t ma y aff ect the pr ogram’s abilit y to perform the instr uctions c ontained in a jour nal file can b e created b y mo dific ations or manipula tions tha t you mak e within the pr ogram. For e xample , if y our jour nal file cr eates se veral sur faces and displa ys da ta on those sur faces, you must be sur e to read in appr opriate case and da ta files b efore reading the jour nal file . Imp ortant At a p oint of time , only one jour nal file c an b e op en f or recording , but y ou c an wr ite a jour nal and a tr anscr ipt file simultaneously .You c an also r ead a jour nal file a t an y time . •Whene ver y ou star t recording a jour nal file , the t ext command /file/set-tui-version "XX.X" is added a t the t op of the file (wher e XX.X corresponds t o the v ersion of ANSY S Fluen t tha t is r ecord- ing the jour nal file). This t ext command c an help jour nals cr eated in an older v ersion t o work pr operly when used in a new er v ersion, as it will hide the new t ext user in terface (TUI) pr ompts and r estore the delet ed TUI pr ompts in tha t new er v ersion. If you ar e wr iting a jour nal file in a t ext edit or, it is r ecommended tha t you add /file/set-tui- version "XX.X" at the t op of the file . Note –The sp ecified v ersion must b e within t wo full r eleases of the v ersion tha t is r unning the jour nal. –To sp ecify v ersion 2019 R3, enter "19.5" for "XX.X" . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 598Reading and Writing F ilesWhether y ou cho ose t o type the t ext command in full or use par tial str ings (as descr ibed in Command Abbreviation ), complet e commands ar e recorded in the jour nal files . Consider the f ollowing e xamples: •Typing in the TUI solve/set/expert , , yes , , will b e recorded in the jour nal file as /solve/set/expert yes no yes no no wher e , or Enter signifies default v alues or en tries, as descr ibed in Text Prompt S ystem. •Typing in the TUI so set ur mom 0.2 pres 0.4 will b e recorded in the jour nal file as t wo separ ate commands: /solve/set/under-relaxation/mom 0.2 /solve/set/under-relaxation/pressure 0.4 Imp ortant •Only succ essfully c omplet ed c ommands ar e recorded . For e xample , if you st opp ed an e xecution of a c ommand using Ctrl+c, it will not b e recorded in the jour nal file . •If a GUI e vent happ ens while a t ext command is in pr ogress, the GUI e vent is r ecorded first. •All default v alues ar e recorded (as in the first e xample ab ove). For additional inf ormation, see the f ollowing sec tion: 3.9.1. Procedur e 3.9.2. Multiple J ournal F iles 3.9.1. Procedur e To star t the jour naling pr ocess, selec t the File/W rite/Start Jour nal... ribbon tab it em. File → Write → Start Jour nal... After y ou en ter a name f or the file in the Selec t File dialo g box, jour nal r ecording b egins .The Start Jour nal... menu it em b ecomes the Stop J our nal menu it em. You c an end jour nal r ecording b y selec ting Stop J our nal, or b y exiting the pr ogram. File → Write → Stop J our nal You c an r ead a jour nal file in to the pr ogram using the Selec t File dialo g box op ened b y selec ting the File/Read/J our nal... ribbon tab it em. File → Read → Jour nal... 599Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Creating and R eading J ournal F ilesJournal files ar e alw ays loaded in the main (tha t is, top-le vel) t ext menu , regar dless of wher e you ar e in the t ext menu hier archy when y ou in voke the r ead c ommand . 3.9.2. Multiple J our nal F iles It is p ossible t o read multiple jour nal files in to Fluen t at onc e. To read multiple jour nal files thr ough the Selec t File dialo g box: 1.Open the Selec t File dialo g box. File → Read → Jour nal... 2.Selec t your files in the or der y ou w ant them r ead in to Fluen t. The or der in which the y will b e read is indic ated b y the r ed b ox in Figur e 3.4: Multiple S elec tion of Journal F iles (p.600 ). Figur e 3.4: Multiple S elec tion of J our nal F iles 3.Click OK to load the selec ted files . Nested J ournal F iles It is p ossible t o cr eate a jour nal file tha t mak es c alls t o other jour nal files . The f ollowing is an e xample of a nest ed jour nal file: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 600Reading and Writing F iles/file/read-journal "E:/Example_journals_example1.jou" "" /file/read-journal "E:/Example_journals_example2.jou" "" /file/read-journal "E:/Example_journals_example3.jou" "" 3.10. Creating Transcr ipt F iles A transcr ipt file c ontains a c omplet e record of all standar d input t o and output fr om ANSY S Fluen t (usually all k eyboard and GUI input and all scr een output). GUI c ommands ar e recorded as Scheme c ode lines in tr anscr ipt files . ANSY S Fluen t creates a tr anscr ipt file b y recording e verything t yped as input or en tered through the GUI, and e verything pr inted as output in the t ext windo w. The pur pose of a tr anscr ipt file is t o pr oduce a r ecord of the pr ogram session f or la ter reference. Because they contain messages and other output , transcr ipt files (unlik e jour nal files), cannot b e read back in to the pr ogram. Imp ortant Only one tr anscr ipt file c an b e op en f or recording a t a time , but y ou c an wr ite a tr anscr ipt and a jour nal file simultaneously .You c an also r ead a jour nal file while a tr anscr ipt r ecording is in pr ogress. To star t the tr anscr iption pr ocess, selec t the File/W rite/Start Transcr ipt... ribbon tab it em. File → Write → Start Transcr ipt... After y ou en ter a name f or the file in the Selec t File dialo g box, transcr ipt r ecording b egins and the Start Transcr ipt... menu it em b ecomes the Stop Transcr ipt menu it em. You c an end tr anscr ipt r ecording b y selec ting Stop Transcr ipt, or b y exiting the pr ogram. File → Write → Stop Transcr ipt 3.11. Imp orting F iles ANSY S Fluen t allo ws you t o imp ort the f ollowing file f ormats: •ABAQUS .inp ,.fil , and .odb files* •CFX .def and .res files •CGNS files* •EnSight files* •ANSY S FIDAP files* •GAMBIT files •HYPERMESH ASCII files* •I-deas U niversal files* 601Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Imp orting F iles•LSTC/DYNA k eyword input files and sta te da tabases* •Marc POST files* •Mechanic al APDL .inp ,.cdb ,.rst , and .rmg files* •NASTR AN B ulk D ata files* •PATRAN N eutr al files* •PLOT3D mesh files* •PTC M echanic a Design studies* •Tecplot files* *Requir es a VKI lic ense Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 602Reading and Writing F ilesFigur e 3.5: The Imp ort Menu Imp ortant Onc e you ha ve imp orted an y 3r d par ty file it is r ecommended tha t you c onfir m tha t the boundar y zones and c ell z ones ar e set up as y ou e xpect. For inf ormation on imp orting par ticle hist ory da ta, see Imp orting P article D ata (p.2037 ). For additional inf ormation, see the f ollowing sec tions: 3.11.1. ABAQUS F iles 3.11.2. CFX F iles 3.11.3. Meshes and D ata in C GNS F ormat 3.11.4. EnS ight Files 603Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Imp orting F iles3.11.5. ANSY S FIDAP N eutr al Files 3.11.6. GAMBIT and G eoM esh M esh F iles 3.11.7. HYPERMESH ASCII F iles 3.11.8. I-deas U niversal F iles 3.11.9. LST C Files 3.11.10. Marc POST F iles 3.11.11. Mechanic al APDL F iles 3.11.12. NASTR AN F iles 3.11.13. PATRAN N eutr al Files 3.11.14. PLOT3D F iles 3.11.15. PTC M echanic a Design F iles 3.11.16. Tecplot F iles 3.11.17. Fluen t 4 C ase F iles 3.11.18. PreBFC F iles 3.11.19. Partition F iles 3.11.20. CHEMKIN M echanism 3.11.1. ABAQUS F iles To imp ort an AB AQUS input file , use the File/Imp ort/AB AQUS/Input F ile... ribbon tab it em. File → Imp ort → ABAQUS → Input F ile... Selec t this menu it em t o op en the Selec t File dialo g box. Specify the name of the AB AQUS Input F ile to be read.The AB AQUS input file (.inp) is a t ext file tha t contains the input descr iption of a finit e elemen t mo del f or the AB AQUS finit e elemen t program. The in terface only pr oduces da tasets asso ciated with the finit e elemen t mo del, no r esults of da tasets ar e pr oduced. Elemen t types c ommonly asso ciated with str uctural analy sis ar e supp orted b y this file f ormat.There is a list of input k eywords tha t are re- cogniz ed in the AB AQUS Input F ile[4] (p.4005 ). To imp ort an AB AQUS filbin file , use the File/Imp ort/AB AQUS/F ilbin F ile... ribbon tab it em. File → Imp ort → ABAQUS → Filbin F ile... Selec t this menu it em t o op en the Selec t File dialo g box. Specify the name of the AB AQUS Filbin F ile to be read.This output file has a .fil extension and c onsists of finit e elemen t mo del and r esults data. To imp ort an AB AQUS ODB file , use the File/Imp ort/AB AQUS/ODB F ile... ribbon tab it em. File → Imp ort → ABAQUS → ODB F ile... Selec t this menu it em t o op en the Selec t File dialo g box. Specify the name of the AB AQUS ODB F ile to be read.This output da tabase file has a .odb extension and c onsists of finit e elemen t mo del and results da ta in the Op enD ocumen t format. 3.11.2. CFX F iles To imp ort a CFX definition file , use the File/Imp ort/CFX/D efinition F ile... ribbon tab it em. File → Imp ort → CFX → Definition F ile... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 604Reading and Writing F ilesSelec t this menu it em t o op en the Selec t File dialo g box. Specify the name of the CFX Definition F ile to be read. Fluen t reads mesh inf ormation fr om the CFX file with .def extensions . For inf ormation about imp orting CFX files , see CFX F iles (p.730). To imp ort a CFX r esult file , use the File/Imp ort/CFX/Result F ile... ribbon tab it em. File → Imp ort → CFX → Result F ile... In the Selec t File dialo g box, specify the name of the CFX Result F ile to be read.Those imp orted files will ha ve .res extensions . Note tha t the Create Zones fr om C CL P hysics D ata option in the Selec t File dialo g boxes allo ws you to cr eate zones fr om the ph ysics da ta objec ts or the pr imitiv e mesh r egion objec ts. Imp ortant CFX file imp ort is a vailable f or 3D c ases only . 3.11.3. Meshes and D ata in C GNS F ormat To imp ort meshes in CFD gener al nota tion sy stem (C GNS) f ormat (.cgns ) into ANSY S Fluen t, use the File/Imp ort/CGNS/M esh... ribbon tab it em. File → Imp ort → CGNS → Mesh... To imp ort a mesh and the c orresponding C GNS da ta, use the File/Imp ort/CGNS/M esh & D ata... ribbon tab it em. File → Imp ort → CGNS → Mesh & D ata... To imp ort only the C GNS da ta, use the File/Imp ort/CGNS/D ata... ribbon tab it em. File → Imp ort → CGNS → Data... Table 3.1: CGNS Variables S upp orted b y ANSY S Fluen t ANSY S Fluen t Name CGNS Variable N ame pressur e Pressur e uu-str ess ReynoldsS tressX X uv-str ess ReynoldsS tressX Y uw-str ess ReynoldsS tressXZ vv-str ess ReynoldsS tressY Y vw-str ess ReynoldsS tressYZ ww-str ess ReynoldsS tressZZ temp erature Temp erature epsilon Turbulen tDissipa tion omega Turbulen tDissipa tionR ate k Turbulen tEner gyKinetic 605Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Imp orting F ilesANSY S Fluen t Name CGNS Variable N ame x-velocity VelocityX y-velocity VelocityY z-velocity VelocityZ Imp ortant •To imp ort da ta correctly, first imp ort the mesh using the mesh only option ( Mesh... ) and set up the b oundar y conditions . For e xample , if a b oundar y zone is of t ype pressur e-outlet and is r ead as outlet , it should b e changed t o pressur e-outlet before imp orting the da ta.Then selec t the appr opriate mo del and r ead the da ta using the da ta only option ( Data... ) •The new and or iginal meshes should ha ve the same z ones , numb ered in the same or der. A warning is issued if the y do not , because inc onsist encies c an cr eate pr oblems with the b oundar y conditions . •ANSY S Fluen t defaults t o the Laminar Visc ous M odel after reading a C GNS mesh. You must selec t the appr opriate mo del b efore reading da ta sinc e ANSY S Fluen t selec tively imp orts only those v alues fr om the C GNS file r equir ed f or a giv en mo del. For e xample , if Epsilon is a vailable in the C GNS file , the mo del must b e changed t o k-epsilon to ensur e tha t ANSY S Fluen t will imp ort this quan tity. 3.11.4. EnSight Files You c an imp ort an EnS ight file using the File/Imp ort/EnSight... ribbon tab it em. File → Imp ort → EnSight... This file f ormat is applied t o both unstr uctured and str uctured da ta, wher e each par t contains its o wn local coordina te ar ray.The EnS ight Gold sof tware pack age, which uses this file f ormat, allo ws you t o analyz e, visualiz e, and c ommunic ate engineer ing da tasets . It allo ws you t o tak e full ad vantage of par- allel pr ocessing and r ender ing and supp orts a r ange of vir tual r ealit y de vices. Further mor e, it enables real-time c ollab oration. When selec ting this option, the Selec t File dialo g box will app ear, wher e you will sp ecify a file name . This file will ha ve an .encas or .case extension. Only the mesh file is r ead in to ANSY S Fluen t, and an y da ta pr esen t is disc arded . 3.11.5. ANSY S FIDAP N eutr al Files You c an r ead an ANSY S FIDAP neutr al file using the File/Imp ort/FIDAP ... ribbon tab it em. File → Imp ort → FIDAP ... In the Selec t File dialo g box, specify the name of the ANSY S FIDAP Neutr al F ile to be read.This file will ha ve an .FDNEUT or .unv file e xtension. ANSY S Fluen t reads mesh inf ormation and z one t ypes from the ANSY S FIDAP file .You must sp ecify b oundar y conditions and other inf ormation af ter reading Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 606Reading and Writing F ilesthis file . For inf ormation ab out imp orting ANSY S FIDAP N eutr al files , see ANSY S FIDAP N eutr al Files (p.733). 3.11.6. GAMBIT and G eoM esh M esh F iles If you ha ve sa ved a neutr al file fr om GAMBIT , rather than an ANSY S Fluen t mesh file , you c an imp ort it in to ANSY S Fluen t using the File/Imp ort/GAMBIT ... ribbon tab it em. File → Imp ort → GAMBIT ... For inf ormation ab out imp orting files fr om GAMBIT and G eoM esh, see GAMBIT M esh F iles (p.724) and GeoM esh M esh F iles (p.724). 3.11.7. HYPERMESH ASCII F iles You c an r ead a HYPERMESH ASCII file using the File/Imp ort/HYPERMESH ASCII... ribbon tab it em. File → Imp ort → HYPERMESH ASCII... HYPERMESH is a high-p erformanc e finit e elemen t pre- and p ostpr ocessor f or p opular finit e elemen t solv ers, allo wing engineers t o analyz e pr oduc t design p erformanc e in a highly in teractive and visual environmen t. When selec ting this option, the Selec t File dialo g box will app ear, wher e you will sp ecify a file name . This file should ha ve an .hm ,.hma , or .hmascii extension. 3.11.8. I-deas U niversal F iles I-deas U niversal files c an b e read in to ANSY S Fluen t with the File/Imp ort/I-deas U niversal... ribbon tab it em. File → Imp ort → I-deas U niversal... Selec t the I-deas U niversal... menu it em t o op en the Selec t File dialo g box. Specify the name of the I-deas U niversal file t o be read. Fluen t reads mesh inf ormation and z one t ypes from the I-deas U niversal file . For inf ormation ab out imp orting I-deas U niversal files , see I-deas U niver- sal F iles (p.725). 3.11.9. LST C Files To imp ort an LST C input file , use the File/Imp ort/LST C/Input F ile... ribbon tab it em. File → Imp ort → LST C → Input F ile... The LST C input file is a t ext file tha t contains the input descr iption of a finit e elemen t mo del f or the LS-D YNA finit e elemen t program. This in terface only pr oduces da tasets asso ciated with the mesh, no results da tasets ar e pr oduced.The elemen t types c ommonly asso ciated with str uctural analy sis ar e supp orted. LSTC input files ha ve the f ollowing file e xtensions:.k,.key , and .dyn 607Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Imp orting F ilesTo imp ort an LST C sta te file , use the File/Imp ort/LST C/State File... ribbon tab it em. File → Imp ort → LST C → State File... The sta te file c onsists of thr ee major sec tions: control da ta, geometr y da ta, and sta te da ta. Each da taset in the sta te da ta sec tion c orresponds t o the time and global da ta it ems asso ciated with each sta te on the da tabase . Dataset a ttribut es include such things as time , ener gy, and momen tum. An LST C sta te file has a .d3plot file e xtension. 3.11.10. Marc POST F iles Marc POST files c an b e read in to ANSY S Fluen t using the File/Imp ort/M arc POST ... ribbon tab it em. File → Imp ort → Marc POST ... Selec t the Marc POST ... menu it em and in the Selec t File dialo g box, specify the name of the file t o be read. These files ar e gener ated using MSC M arc, a nonlinear finit e elemen t program. MSC M arc allo ws you to stud y def ormations tha t exceed the linear elastic r ange of some ma terials, enabling y ou t o assess the str uctural in tegrity and p erformanc e of the ma terial. It also allo ws you t o simula te def ormations that are par t-to-par t or par t-to-self c ontact under a r ange of c onditions . 3.11.11. Mechanic al APDL F iles To imp ort a M echanic al APDL input file , use the File/Imp ort/M echanic al APDL/Input F ile... ribbon tab it em. File → Imp ort → Mechanic al APDL → Input F ile... Selec t this menu it em t o op en the Selec t File dialo g box. Specify the name of the M echanic al AP- DL Prep7 F ile to be read. Fluen t reads mesh inf ormation fr om the M echanic al APDL file with .ans , .neu ,.cdb , and .prep7 extensions . For inf ormation ab out imp orting M echanic al APDL files , see Mechanic al APDL F iles (p.729). To imp ort a M echanic al APDL r esult file , use the File/Imp ort/M echanic al APDL/Result F ile... ribbon tab it em. File → Imp ort → Mechanic al APDL → Result F ile... In the Selec t File dialo g box. Specify the name of the M echanic al APDL Result F ile to be read.Those imp orted files will ha ve .rst ,.rth , and .rmg extensions . 3.11.12. NASTR AN F iles You c an r ead NASTR AN B ulkda ta files in to ANSY S Fluen t with the File/Imp ort/NASTR AN/Bulkda ta File... ribbon tab it em. File → Imp ort → NASTR AN → Bulkda ta F ile... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 608Reading and Writing F ilesWhen y ou selec t the Bulkda ta F ile... menu it em, the Selec t File dialo g box will app ear and y ou will specify the name of the NASTR AN File to be read.This file will ha ve .nas ,.dat ,.bdf file e xtensions . Fluen t reads mesh inf ormation fr om the NASTR AN file . For inf ormation ab out imp orting NASTR AN files , see NASTR AN F iles (p.727). To imp ort NASTR AN Op2 files in to ANSY S Fluen t, use the File/Imp ort/NASTR AN/Op2 F ile... ribbon tab it em. File → Imp ort → NASTR AN → Op2 F ile... In the Selec t File dialo g box, specify the name of the NASTR AN Output2 F ile to be read.This file is an output binar y da ta file tha t contains da ta used in the NASTR AN finit e elemen t program. This file will ha ve .op2 file e xtension. 3.11.13. PATRAN N eutr al Files To read a P ATRAN N eutr al file z oned b y named c omp onen ts (tha t is, a file in which y ou ha ve gr oup ed nodes with the same sp ecified gr oup name), use the File/Imp ort/PATRAN N eutr al... ribbon tab it em. File → Imp ort → PATRAN N eutr al... Selec ting this menu it em op ens the Selec t File dialo g box. Specify the name of the P ATRAN N eutr al file to be read (e xtension .neu ,.out , or .pat ). Fluen t reads mesh inf ormation fr om the P ATRAN N eut- ral file . For inf ormation ab out imp orting P ATRAN N eutr al files , see PATRAN N eutr al Files (p.728). 3.11.14. PLOT3D F iles To imp ort a PL OT3D mesh file , use the File/Imp ort/PL OT3D G rid... ribbon tab it em. File → Imp ort → PLOT3D G rid... The PL OT3D mesh files ha ve .p3d ,.bin ,.x,.xyz , or .grd file e xtensions . These file f ormats ma y be formatted, unf ormatted or binar y. 3.11.15. PTC M echanic a Design F iles To imp ort a PT C M echanic a Design file , use the File/Imp ort/PT C M echanic a D esign... ribbon tab it em. File → Imp ort → PTC M echanic a D esign... This will op en the Selec t File dialo g box. Specify the name of the neutr al file t o be read. The PT C M echanic a Design file c ontains analy sis, mo del and r esults da ta. Only the binar y form of the results da ta files is supp orted. 609Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Imp orting F ilesThe f orm of the file must ha ve the .neu extension. Imp ortant Mechanic a results c onsists of an en tire dir ectory str ucture of files , called a “stud y” in M ech- anic a terminolo gy, which must b e used in e xactly the f orm tha t Mechanic a or iginally gen- erates it. ANSY S Fluen t’s VKI in terface keys on the .neu file and c an tr averse the dir ectory structure from ther e to acc ess the other files tha t it needs . 3.11.16. Tecplot F iles To imp ort a Tecplot file , use the File/Imp ort/Tecplot ... ribbon tab it em. File → Imp ort → Tecplot ... This will op en the Selec t File dialo g box. Specify the name of the neutr al file t o be read. The Tecplot file is a binar y file . Only the mesh is r ead in to ANSY S Fluen t and an y da ta pr esen t is dis- carded . The f orm of the file must ha ve the .plt extension. ANSY S Fluen t supp orts the imp ortation of p oly- hedr al cells and files cr eated b y Tecplot v ersion 7.1–11.2, except f or v ersion 11.0 (which is unsupp orted). 3.11.17. Fluen t 4 C ase F iles You c an r ead a F luen t 4 c ase file using the File/Imp ort/Fluen t 4 C ase F ile... ribbon tab it em. File → Imp ort → Fluen t 4 C ase F ile... Selec t the Fluen t 4 C ase F ile... menu it em t o op en the Selec t File dialo g box. Specify the name of the F luen t 4 c ase file t o be read. ANSY S Fluen t reads only mesh inf ormation and z one t ypes fr om the Fluen t 4 c ase file .You must sp ecify b oundar y and c ell z one c onditions , mo del par amet ers, ma terial properties, and other inf ormation af ter reading this file . For inf ormation ab out imp orting F luen t 4 c ase files , see FLUENT 4 C ase F iles (p.732). 3.11.18. PreBFC F iles You c an r ead a P reBFC str uctured mesh file in to ANSY S Fluen t using the File/Imp ort/PreBFC F ile... ribbon tab it em. File → Imp ort → PreBFC F ile... Selec t the PreBFC F ile... menu it em t o op en the Selec t File dialo g box. Specify the name of the PreBFC str uctured mesh file t o be read. Fluen t reads mesh inf ormation and z one t ypes fr om the P reB- FC mesh file . For inf ormation ab out imp orting P reBFC mesh files , see PreBFC M esh F iles (p.725). 3.11.19. Partition F iles To perform METIS par titioning on an unpar titioned mesh, use the File/Imp ort/Partition/M etis ... ribbon tab it em. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 610Reading and Writing F ilesFile → Imp ort → Partition → Metis ... You ma y also par tition each c ell z one individually , using the File/Imp ort/Partition/M etis Z one ... ribbon tab it em. File → Imp ort → Partition → Metis Z one ... See Using the P artition F ilter (p.3089 ) for detailed inf ormation ab out par titioning . 3.11.20. CHEMKIN M echanism To imp ort a CHEMKIN f ormat, you c an imp ort the mechanism file in to ANSY S Fluen t using the File/Imp ort/CHEMKIN M echanism... ribbon tab it em ( Figur e 15.5: The Imp ort CHEMKIN F ormat Mechanism D ialog Box for Volumetr ic Kinetics (p.1626 )). File → Imp ort → CHEMKIN M echanism... See Imp orting a Volumetr ic Kinetic M echanism in CHEMKIN F ormat (p.1624 ) for detailed inf ormation on imp orting a CHEMKIN M echanism file . 3.12. Exporting S olution D ata The cur rent release of ANSY S Fluen t allo ws you t o export da ta to AB AQUS, , Mechanic al APDL Input , ASCII, AVS, CDA T for CFD-P ost and EnS ight, CGNS, Data Explor er, EnS ight, FAST, FIELD VIEW, I-deas , NASTR AN, PATRAN, TAITherm, and Tecplot f ormats.Exporting S olution D ata af ter a C alcula tion (p.613) explains ho w to export solution da ta in these f ormats af ter the c alcula tion is c omplet e, and ABAQUS Files (p.614) to Tecplot F iles (p.625) provide sp ecific inf ormation f or each t ype of File Type. For inf orm- ation ab out e xporting solution da ta dur ing tr ansien t flo w solutions , see Exporting D ata D uring a Tran- sien t Calcula tion (p.627). For NASTR AN, ABAQUS, Mechanic al APDL Input , I-deas U niversal, and P ATRAN file f ormats, the f ollowing quan tities ar e exported [4] (p.4005 ): •Nodes, Elemen ts •Node S ets (B oundar y Conditions) •Temp erature •Pressur e •Heat Flux •Heat Transf er C oefficien t •Force To gener ate the f orce da ta tha t is e xported f or no des a t boundar ies, ANSY S Fluen t performs the f ol- lowing st eps: 1.Facial f orce for each w all fac e is c alcula ted b y summing the pr essur e force, visc ous f orce and sur face tension f orce of the fac e. 611Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Exporting S olution D ata2.Partial f orce for each w all fac e is c alcula ted b y dividing its facial f orce by its numb er of shar ed no des. 3.Total f orce for each w all no de is c alcula ted b y summing the par tial f orces of all the w all fac es shar ing that no de. For additional inf ormation, see the f ollowing sec tion: 3.12.1. Exp orting Limita tions 3.12.1. Exporting Limita tions Note the f ollowing limita tions when e xporting solution da ta: •When using the par allel v ersion of ANSY S Fluen t, you c an only e xport to the f ollowing pack ages: –ABAQUS –CDA T for CFD-P ost and EnS ight –ASCII –CGNS –EnSight Case G old –Fieldview U nstr uctured –I-deas U niversal –Mechanic al APDL Input –NASTR AN –PATRAN –TAITherm Note that par allel TAITherm e xport is onl y available f or sur face data. –Tecplot The e xported file will b e wr itten b y the host pr ocess (see Introduc tion t o Parallel P rocessing (p.3045 )). Note tha t the memor y requir ed t o wr ite the file ma y exceed the memor y available t o the host pr ocess. •When using the ser ial v ersion of ANSY S Fluen t, you c an only e xport sur face da ta for TAITherm sof tware. •The solution mo de of F luen t cannot imp ort sur faces. Consequen tly, if you e xport a file fr om ANSY S Fluen t with sur faces selec ted, you ma y not b e able t o read these files back in to the solution mo de. However, the meshing mo de of F luen t can imp ort sur face da ta (see the F luen t Meshing sec tion of the U ser’s Guide f or details). •The following file t ypes requir e a VKI lic ense: ABAQUS, CGNS, Ideas-U niversal, NASTR AN, PATRAN, Tecplot •ANSY S Fluen t supp orts exporting p olyhedr al da ta only f or ASCII, CDA T for CFD-P ost and EnS ight, CGNS, EnSight Case G old, NASTR AN, TAITherm,Tecplot and F ieldview U nstr uctured file f ormats. For fur ther details , see ASCII F iles (p.615),CDA T for CFD-P ost and EnS ight (p.615),CGNS F iles (p.617),EnSight Case Gold F iles (p.618),NASTR AN F iles (p.623),TAITherm Files (p.624) and FieldV iew U nstr uctured F iles (p.621). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 612Reading and Writing F iles•If the files tha t are exported dur ing multiple tr ansien t simula tions ar e to be used as a set , you must mak e sure tha t all of the simula tions ar e run on the same pla tform, using the same numb er of pr ocessors .This ensur es tha t all of the files ar e compa tible with each other . •Data on user defined/cr eated sur faces is not a vailable f or e xport to EnS ight Case G old file f ormat. 3.13. Exporting S olution D ata af ter a C alcula tion To export solution da ta to a diff erent file f ormat after a c alcula tion is c omplet e, use the Export Dialog Box (p.3757 ) (Figur e 3.6: The Exp ort Dialog Box (p.613)). File → Export → Solution D ata... Figur e 3.6: The E xport Dialo g Box Information c oncerning the nec essar y steps and a vailable options f or each File Type are list ed in ABAQUS Files (p.614) to Tecplot F iles (p.625). For details ab out gener al limita tions f or e xporting solution da ta and the manner in which it is e xported, see Exporting S olution D ata (p.611). For additional inf ormation, see the f ollowing sec tions: 3.13.1. ABAQUS F iles 3.13.2. Mechanic al APDL Input F iles 3.13.3. ASCII F iles 3.13.4. AVS Files 3.13.5. CDA T for CFD-P ost and EnS ight 3.13.6. CGNS F iles 3.13.7. Data Explor er Files 3.13.8. EnS ight Case G old F iles 3.13.9. FAST F iles 613Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Exporting S olution D ata af ter a C alcula tion3.13.10. FAST S olution F iles 3.13.11. FieldV iew U nstr uctured F iles 3.13.12. I-deas U niversal F iles 3.13.13. NASTR AN F iles 3.13.14. PATRAN F iles 3.13.15. TAITherm Files 3.13.16. Tecplot F iles 3.13.1. ABAQUS F iles Selec t AB AQUS fr om the File Type drop-do wn list and cho ose the sur face(s) f or which y ou w ant to write da ta in the Surfaces list. If no sur faces ar e selec ted, the en tire domain is e xported. When the Energy Equa tion is enabled in the Ener gy Dialog Box (p.3252 ), you c an cho ose the loads t o be wr itten based on the k ind of finit e elemen t analy sis y ou in tend t o under take. By selec ting Structural in the Analy sis list, you c an selec t the f ollowing Structural L oads :Force,Pressur e, and Temp erature. By selec ting Thermal in the Analy sis list, you c an selec t the f ollowing Thermal L oads :Temp erature, Heat Flux, and Heat Trans C oeff. Note the f ollowing limita tions with these loads: •When the Energy Equa tion is disabled , only the Structural L oads options of Force and Pressur e are available . •Loads ar e wr itten only on b oundar y walls when the en tire domain is e xported (tha t is, if no Surfaces are selec ted). Click the Write... butt on t o sa ve the file , using the Selec t File dialo g box.The e xported file f ormat of ABAQUS (file.inp ) contains c oordina tes, connec tivit y, zone gr oups , and optional loads . Export of da ta to AB AQUS is v alid only f or solid z ones or f or those sur faces tha t lie a t the in tersec tion of solid z ones .Temp erature da ta is e xported f or the whole domain. You ha ve the option of e xporting da ta a t sp ecified in tervals dur ing a tr ansien t calcula tion thr ough the Automa tic E xport dialo g box. See Exporting D ata D uring a Transien t Calcula tion (p.627) for the c omplet e details . 3.13.2. Mechanic al APDL Input F iles Selec t Mechanic al APDL Input fr om the File Type drop-do wn list and cho ose the sur face(s) f or which you w ant to wr ite da ta in the Surfaces list. If no sur faces ar e selec ted, the en tire domain is e xported. When the Energy Equa tion is enabled in the Ener gy Dialog Box (p.3252 ), you c an cho ose the loads t o be wr itten based on the k ind of finit e elemen t analy sis y ou in tend t o under take. By selec ting Structural in the Analy sis list, you c an selec t the f ollowing Structural L oads :Force,Pressur e, and Temp erature. By selec ting Thermal in the Analy sis list, you c an selec t the f ollowing Thermal L oads :Temp erature, Heat Flux, and Heat Trans C oeff. Note the f ollowing limita tions with these loads: •When the Energy Equa tion is disabled , only the Structural L oads options of Force and Pressur e are available . •Loads ar e wr itten only on b oundar y walls when the en tire domain is e xported (tha t is, if no Surfaces are selec ted). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 614Reading and Writing F ilesClick the Write... butt on t o sa ve the file , using the Selec t File dialo g box. ANSY S Fluen t exports an input file tha t contains M echanic al APDL finit e elemen t inf ormation including no des, elemen ts, and loads tha t can b e used t o do finit e elemen t analy sis in M echanic al APDL with minimal eff ort.The file format is wr itten in .cdb format.The e xport of M echanic al APDL Input files is in ASCII f ormat and ther efore is a vailable on all pla tforms. You ha ve the option of e xporting da ta a t sp ecified in tervals dur ing a tr ansien t calcula tion thr ough the Automa tic E xport dialo g box. See Exporting D ata D uring a Transien t Calcula tion (p.627) for the c omplet e details . 3.13.3. ASCII F iles Selec t ASCII from the File Type drop-do wn list and cho ose the sur face(s) f or which y ou w ant to wr ite data in the Surfaces list. If no sur faces ar e selec ted, the en tire domain is e xported. Also selec t the variable(s) f or which da ta is t o be sa ved in the Quan tities list. When e xporting ASCII files , you ha ve the f ollowing options: •Selec t the Location from which the v alues of sc alar func tions ar e to be tak en. If you sp ecify the da ta Location as Node, then the da ta values a t the no de p oints ar e exported. If you cho ose Cell C enter, then the da ta values fr om the c ell c enters ar e exported. For b oundar y fac es, it is the fac e center values tha t are exported when the Cell C enter option is selec ted. •Selec t the Delimit er separ ating the fields ( Comma or Spac e). Click the Write... butt on t o sa ve the file , using the Selec t File dialo g box. ANSY S Fluen t will e xport a single ASCII file c ontaining c oordina tes, optional loads , and sp ecified sc alar func tion da ta. Imp ortant ANSY S Fluen t supp orts exporting p olyhedr al da ta to ASCII. You ha ve the option of e xporting da ta a t sp ecified in tervals dur ing a tr ansien t calcula tion thr ough the Automa tic E xport dialo g box. See Exporting D ata D uring a Transien t Calcula tion (p.627) for the c omplet e details . 3.13.4. AVS Files Selec t AVS from the File Type drop-do wn list and sp ecify the sc alars y ou w ant in the Quan tities list. Click the Write... butt on t o sa ve the file , using the Selec t File dialo g box. An AVS version 4 UCD file contains c oordina te and c onnec tivit y inf ormation and sp ecified sc alar func tion da ta. You ha ve the option of e xporting da ta a t sp ecified in tervals dur ing a tr ansien t calcula tion thr ough the Automa tic E xport dialo g box. See Exporting D ata D uring a Transien t Calcula tion (p.627) for the c omplet e details . 3.13.5. CDA T for CFD-P ost and E nSight The default output file f or ANSY S Fluen t is a .dat file (see Reading and Writing D ata Files (p.589)), however, when r eading F luen t output in to CFD-P ost, a .cdat file is str ongly pr eferred..cdat files 615Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Exporting S olution D ata af ter a C alcula tionare also c ompa tible with EnS ight, although EnS ight Case G old files ( EnSight Case G old F iles (p.618)) are recommended f or the b est p erformanc e in EnS ight. Imp ortant When r eading .dat files in to ANSY S CFD-P ost, some v ariables ma y sho w inc orrect values in some c onditions .You should use .cdat files inst ead of .dat files . If you don't , then you ma y need t o cr oss check these v alues b etween CFD-P ost and F luen t. To export da ta to files tha t are compa tible with ANSY S CFD-P ost and Ensigh t, selec t CDA T for CFD- Post and E nSight from the File Type drop-do wn list. Next, specify the Cell Z ones tha t contain the data you w ant exported; not e tha t by default , all of the c ell z ones will b e exported. If you w ant to export solution da ta for par ticular sur faces, then selec t them fr om the Surfaces list. Onc e you ha ve chosen your c ells z ones and/or sur faces y ou must selec t the Quan tities tha t you w ant to export.When selec ting the v ariables , be sur e to include an y variable tha t was used t o cr eate an isosur face or clipp ed sur face (as descr ibed in Isosur faces (p.2748 ) and Clipping Sur faces (p.2750 ), respectively); other wise , the sur face will not b e created pr operly if y ou tr y to read the e xported sta te file in CFD-P ost. Specify the f ormat of the .cdat file b y selec ting either Binar y or ASCII from the Format list. The advantage of the binar y format is tha t it tak es less time t o load the e xported da ta in to ANSY S CFD- Post and r equir es less st orage spac e. Note tha t the f ormat for the .cst will alw ays be ASCII. By default , Fluen t will wr ite a c ase file (tha t is,.cas ) along with the CDA T for CFD-P ost and E nSight files . If you do not w ant such a c ase file f or an y reason (f or e xample ., to impr ove I/O p erformanc e or save disc spac e), disable the Write Case F ile option. Disabling this option is only r ecommended if y ou are performing multiple e xport op erations f or a c ase file tha t is not changing . Click the Write... butt on t o sa ve the files , using the Selec t File dialo g box. A .cdat file is wr itten, containing the sp ecified v ariable da ta for the sp ecified c ell z ones and all of the b oundar y zones . A state file (tha t is,.cst ) is also wr itten, which c ontains the f ollowing sur faces tha t you cr eated in F luen t for p ostpr ocessing: point sur faces, line sur faces, plane sur faces, isosur faces, and clipp ed sur faces (see Creating Sur faces and C ell R egist ers f or D ispla ying and R eporting D ata (p.2727 )). Note Impr inted sur faces defined in ANSY S Fluen t are not a vailable f or p ostpr ocessing in ANSY S CFD-P ost. Imp ortant When y ou r ead the .cdat file in to ANSY S CFD-P ost, the applic ation will a ttempt t o read in the c ase file tha t produced the da ta b y looking in the f older f or a .cas file with the same pr efix. If the c ase file is not in tha t folder (e .g., if y ou disabled the Write Case F ile option when e xporting), ANSY S CFD-P ost will pr ompt y ou t o sp ecify the appr opriate case file. Imp ortant Before loading the .cst file in to ANSY S CFD-P ost, mak e sur e tha t the .cas and .cdat files ar e alr eady loaded f or the session. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 616Reading and Writing F ilesYou ha ve the option of e xporting da ta a t sp ecified in tervals dur ing a tr ansien t calcula tion thr ough the Automa tic E xport dialo g box. See Exporting D ata D uring a Transien t Calcula tion (p.627) for the c omplet e details . 3.13.6. CGNS F iles Selec t CGNS from the File Type drop-do wn list and sp ecify the sc alars y ou w ant in the Quan tities list. Selec t the Location from which the v alues of sc alar func tions ar e to be tak en. If you sp ecify the da ta Location as Node, then the da ta v alues a t the no de p oints ar e exported. If you cho ose Cell C enter, then the da ta v alues fr om the c ell c enters ar e exported. For b oundar y fac es, it is the fac e center v alues that are exported when the Cell C enter option is selec ted. Click the Write... butt on t o sa ve the file , using the Selec t File dialo g box. CGNS (CFD gener al nota tion system) is a single file (f or e xample ,file.cgns ) containing c oordina tes, connec tivit y, zone inf ormation, velocity, and selec ted sc alars . Imp ortant ANSY S Fluen t supp orts exporting p olyhedr al da ta to CGNS. You ha ve the option of e xporting da ta a t sp ecified in tervals dur ing a tr ansien t calcula tion thr ough the Automa tic E xport dialo g box. See Exporting D ata D uring a Transien t Calcula tion (p.627) for the c omplet e details . 3.13.7. Data E xplor er F iles Selec t Data E xplor er from the File Type drop-do wn list and cho ose the sur face(s) f or which y ou w ant to wr ite da ta in the Surfaces list. If no sur faces ar e selec ted, the en tire domain is e xported. Also sp ecify the sc alars y ou w ant in the Quan tities list. Imp ortant When y ou ar e exporting da ta for D ata Explor er, EnS ight Case G old, or I-deas U niversal and the r eference zone is not a sta tionar y zone , the da ta in the v elocity fields is e xported b y default as v elocities r elative to the motion sp ecific ation of tha t zone .This da ta is alw ays exported, even if y ou do not cho ose t o export an y sc alars . Any velocities tha t you selec t to export as sc alars in the Quan tities list (f or e xample ,X Velocity,Y Velocity,Radial Velocity, and so on) ar e exported as absolut e velocities . For all other t ypes of e xported files , the v e- locities e xported b y default ar e absolut e velocities . Click the Write... butt on t o sa ve the file , using the Selec t File dialo g box. A single file (f or e xample , file.dx ) is e xported, containing c oordina te, connec tivit y, velocity, and sp ecified func tion da ta. You ha ve the option of e xporting da ta a t sp ecified in tervals dur ing a tr ansien t calcula tion thr ough the Automa tic E xport dialo g box. See Exporting D ata D uring a Transien t Calcula tion (p.627) for the c omplet e details . 617Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Exporting S olution D ata af ter a C alcula tion3.13.8. EnSight Case G old F iles When e xporting t o EnS ight, you c an cho ose t o export the da ta asso ciated with a single da ta file , or you c an e xport the da ta asso ciated with multiple files tha t were gener ated b y a tr ansien t solution. •To export the solution da ta fr om a single da ta file , read in the c ase and da ta file and op en the Export dialo g box. File → Export → Solution D ata... Then p erform the f ollowing st eps in the Export dialo g box: 1.Selec t EnSight Case G old from the File Type drop-do wn list. 2.Selec t the Location from which the v alues of sc alar func tions ar e to be tak en. If you sp ecify the da ta Location as Node, then the da ta values a t the no de p oints ar e exported. If you cho ose Cell C enter, then the da ta values fr om the c ell c enters ar e exported. For b oundar y fac es, it is the fac e center values that are exported when the Cell C enter option is selec ted. 3.Specify the f ormat of the file b y selec ting either Binar y or ASCII from the Format list. The ad vantage of the binar y format is tha t it tak es less time t o load the e xported files in to EnS ight. 4.(optional) S elec t the Cell Z ones from which y ou w ant da ta exported (y ou must selec t at least one z one). By default , all of the c ell z ones ar e selec ted. 5.(optional) S elec t the Interior Z one S urfaces from which y ou w ant da ta exported. By default , the da ta being e xported is tak en fr om the en tire ANSY S Fluen t domain. The Interior Z one S urfaces selec tion list allo ws you t o also sp ecify tha t the da ta b e tak en fr om selec ted z one sur faces whose Type is iden tified as interior in the Boundar y Conditions task page . Note Data on user defined/cr eated sur faces is not a vailable f or e xport to EnS ight Case G old file f ormat. 6.Selec t the sc alars y ou w ant to wr ite from the Quan tities selec tion list. 7.Click the Write... butt on t o op en the Selec t File dialo g box, which y ou c an use t o sa ve a file tha t contains the sp ecified v ariable da ta for the sp ecified c ell z ones , the sp ecified in terior z one sur faces, and all of the b oundar y zones . •To export solution da ta asso ciated with multiple files tha t were gener ated b y a tr ansien t solution, you must first mak e sur e tha t the f ollowing cr iteria ar e met: –All of the r elevant case and da ta files must b e in the w orking f older . –The da ta files must b e separ ated b y a c onsist ent numb er of time st eps. Next, enter the f ollowing t ext command in the c onsole: file → transient-export → ensight-gold-from-existing-files Then, enter responses t o the f ollowing pr ompts in the c onsole: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 618Reading and Writing F iles1.EnSight Case Gold file name Enter the name y ou w ant assigned t o the e xported files . 2.Case / Data file selection by base name? Enter yes if the c ase and da ta files shar e a “base name ” (tha t is, a common initial str ing of char acters). The alphanumer ic or der of the full names must c orrespond t o the or der in which the files w ere created.You will then b e pr ompt ed t o en ter the base name a t the Case / Data file base name prompt tha t follows. For e xample , with a set of files named elbow-0001 , elbow-0002 ,elbow-0003 , and so on, enter elbow- for the base name . Enter no if y ou ha ve created an ASCII file in the w orking f older tha t lists the names of the da ta files in or der of when the y were created.The file should list one da ta file name p er line .You will then b e pr ompt ed t o en ter the name of this file a t the Provide the file name which contains the data file names prompt tha t follows. Note tha t you must include the file e xtension if an y in y our en try at the pr ompt. 3.Specify Skip Value Enter an in teger v alue t o sp ecify the numb er of files y ou w ant to sk ip in b etween e xporting files from the sequenc e. For e xample , enter 1 to export every other file , enter 2 to export every thir d file, and so on. 4.Cell-Centered? Enter yes if y ou w ant to export the da ta v alues fr om the c ell c enters (or fac e center v alues , for boundar y fac es). Enter no if y ou w ant to export the da ta v alues fr om the no de p oints. 5.Write separate file for each time step for each variable? Enter yes if y ou w ant separ ate EnS ight Case G old files wr itten f or each time st ep. Other wise , all of the da ta for the .scl1 and .vel files will b e combined in to a single file f or each. 6.Write in binary format? Enter yes to wr ite the files in binar y format. Other wise , the y will b e wr itten in ASCII f ormat.The advantage of the binar y format is tha t it tak es less time t o load the e xported files in to EnS ight. 7.Specify Data File Frequency Enter the numb er of time st eps b etween the da ta files b eing e xported. 8.Separate case file for each time step? Enter no if all the da ta files w ere gener ated fr om the same c ase file (tha t is, the simula tion in volved a sta tic mesh). Note tha t the name of the c ase file must b e the same (not including the e xtension) as the name of the first da ta file in the sequenc e. Enter yes if the da ta files w ere gener ated fr om the diff erent case files (tha t is, the simula tion involved a sliding or d ynamic mesh). Note tha t the names of the c ase files must b e the same (not including the e xtension) as the names of the c orresponding da ta files . 619Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Exporting S olution D ata af ter a C alcula tion9.Read the case file? Enter no if the first (or only , for a sta tic mesh) c ase file is alr eady in memor y. Enter yes if the first (or only , for a sta tic mesh) c ase file is not already in memor y. 10.cell zone id/name(1) Enter the name or ID of an y cell z one fr om which y ou w ant da ta e xported. By default , the da ta being e xported is tak en fr om the en tire ANSY S Fluen t domain. After y ou sp ecify the first c ell zone , you will b e pr ompt ed t o sp ecify the sec ond one , and so on, until you pr ess Enter without typing an y char acters. 11.Interior Zone Surfaces(1) Enter the name of an y interior z one sur face from which y ou w ant da ta e xported. By default , the data b eing e xported is tak en fr om the en tire ANSY S Fluen t domain. This pr ompt allo ws you t o also sp ecify tha t the da ta b e tak en fr om selec ted z one sur faces whose Type is iden tified as in- terior in the Boundar y Conditions task page . After y ou sp ecify the first in terior z one sur face, you will b e pr ompt ed t o sp ecify the sec ond one , and so on, until you pr ess Enter without t yping any char acters. 12.EnSight Case Gold scalar(1) else q to continue Enter in the first sc alar quan tity you w ant exported.You c an pr ess the Enter key to pr int a list of a vailable sc alar quan tities in the c onsole . After y ou en ter the first quan tity, you will b e prompt ed t o en ter the sec ond quan tity, and so on, until you en ter q.The EnS ight Case G old files will then b e wr itten. When e xporting t o EnS ight Case G old, files will b e created with the f ollowing f our f ormats: •A geometr y file (f or e xample ,file.geo ) containing the c oordina tes and c onnec tivit y inf ormation. •A velocity file (f or e xample ,file.vel ) containing the v elocity. •A sc alar file (f or e xample ,file.scl1 ) for each selec ted v ariable or func tion. •An EnS ight case file (f or e xample ,file.encas ) tha t contains details ab out the other e xported files . Imp ortant •For non-sta tionar y reference zones , all the v elocities ar e exported t o EnS ight as v elocities r elative to the selec ted r eference zone . See the inf ormational not e in Data Explor er Files (p.617) for fur ther details . •ANSY S Fluen t supp orts exporting p olyhedr al da ta to EnS ight. You also ha ve the option of e xporting da ta a t sp ecified in tervals dur ing a tr ansien t calcula tion thr ough the Automa tic E xport dialo g box. For details , see Exporting D ata D uring a Transien t Calcula tion (p.627). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 620Reading and Writing F iles3.13.9. FAST F iles This file t ype is v alid only f or tr iangular and t etrahedr al meshes . Selec t FAST from the File Type drop- down list and selec t the sc alars y ou w ant to wr ite in the Quan tities list. Click the Write... butt on t o sa ve the file f or the sp ecified func tion(s), using the Selec t File dialo g box. The f ollowing files ar e wr itten: •A mesh file in e xtended P lot3D f ormat containing c oordina tes and c onnec tivit y. •A velocity file c ontaining the v elocity. •A sc alar file f or each selec ted v ariable or func tion. You ha ve the option of e xporting da ta a t sp ecified in tervals dur ing a tr ansien t calcula tion thr ough the Automa tic E xport dialo g box. See Exporting D ata D uring a Transien t Calcula tion (p.627) for the c omplet e details . 3.13.10. FAST S olution F iles This file t ype is v alid only f or tr iangular and t etrahedr al meshes . Selec t FAST S olution from the File Type drop-do wn list and click the Write... butt on. A single file is wr itten c ontaining densit y, velocity, and t otal ener gy da ta. You ha ve the option of e xporting da ta a t sp ecified in tervals dur ing a tr ansien t calcula tion thr ough the Automa tic E xport dialo g box. See Exporting D ata D uring a Transien t Calcula tion (p.627) for the c omplet e details . 3.13.11. FieldVie w U nstr uctured F iles Selec t Field view U nstr uctured from the File Type drop-do wn list. Next, specify the c ell z ones and surfaces fr om which y ou w ant da ta e xported b y mak ing selec tions in the Cell Z ones or Surfaces lists (you must selec t at least one z one or sur face); not e tha t by default , all of the c ell z ones will b e exported. Then selec t the sc alars y ou w ant to wr ite in the Quan tities list. Finally , click the Write... butt on t o open the Selec t File dialo g box, which y ou c an use t o sa ve a file tha t contains the sp ecified func tion(s) for the sp ecified c ell z ones and asso ciated b oundar y zones or sur faces. The f ollowing files ar e wr itten: •A binar y file (f or e xample ,file.fvuns ) containing c oordina te and c onnec tivit y inf ormation and sp ecified scalar func tion da ta. In par allel, each par tition wr ites to this file with a gr id for each c ell z one or sur face that is e xported.This allo ws par allel p ostpr ocessing in F ieldV iew. •A regions file (f or e xample ,file.fvuns.fvreg ) containing inf ormation ab out the c ell z ones or sur faces and the fr ame of r eference. It also includes inf ormation ab out which gr ids mak e up the v arious c ell z ones or sur faces. The c ell z one and sur face inf ormation includes the names of the c ell z ones/sur faces along with the mesh numb ers. For the mo ving fr ame of r eference, the r egions file c ontains inf ormation ab out the origin, the axis of r otation and the r otation sp eed.Volume da ta is wr itten using the absolut e frame of reference. 621Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Exporting S olution D ata af ter a C alcula tionIf you ar e running multiple st eady-sta te solutions on the same mesh, you c an e xport only the da ta files and a void the r epeated wr iting of the mesh file b y using the f ollowing TUI c ommand f or sur faces and c ell z ones: file/export/fieldview-unstruct-data file_name(list_of_sur faces)(list_of_z ones) list_of_sc alarsq wher e •file_name specifies the name (without the e xtension) of the file tha t you w ant to wr ite. •list_of_sur faces specifies the list of sur faces (separ ated b y spac es, tha t is, no c ommas) fr om which y ou w ant data exported. If you w ant to sp ecify all of the sur faces, enter * within the par entheses . •list_of_z ones specifies the list of c ell z ones (separ ated b y spac es, tha t is, no c ommas) fr om which y ou w ant data exported. If you w ant to sp ecify all of the c ell z ones , enter * within the par entheses . •list_of_sc alars specifies the list of c ell func tions (separ ated b y spac es, tha t is, no c ommas) tha t you w ant to write to the e xported file .The q input t ermina tes the list. For e xample , the input x-velocity cell- zone q will selec t velocity and the c ell v olume . To export only the da ta files f or sur faces, use the f ollowing TUI c ommand: file/export/fieldview-unstruct-surfaces 2 file_name(list_of_sur faces)list_of_sc alars q wher e •2 specifies tha t you w ant to wr ite a F ieldview unstr uctured r esults only file . •file_name specifies the name (without the e xtension) of the file tha t you w ant to wr ite. •list_of_sur faces specifies the list of sur faces (separ ated b y spac es, tha t is, no c ommas) fr om which y ou w ant data exported. If you w ant to sp ecify all of the sur faces, enter * within the par entheses . •list_of_sc alars specifies the list of c ell func tions (separ ated b y spac es, tha t is, no c ommas) tha t you w ant to write to the e xported file .The q input t ermina tes the list. For e xample , the input x-velocity q will selec t only the velocity. You ha ve the option of e xporting da ta a t sp ecified in tervals dur ing a tr ansien t calcula tion thr ough the Automa tic E xport dialo g box. See Exporting D ata D uring a Transien t Calcula tion (p.627) for the c omplet e details . 3.13.12. I-deas U niversal F iles Imp ortant If you in tend t o export da ta to I-deas , ensur e tha t the mesh do es not c ontain p yramidal elemen ts, as these ar e cur rently not supp orted b y I-deas . Selec t I-deas U niversal from the File Type drop-do wn list. Selec t the sur face(s) f or which y ou w ant to wr ite da ta in the Surfaces list. If no sur faces ar e selec ted, the en tire domain is e xported.You c an specify which sc alars y ou w ant in the Quan tities list. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 622Reading and Writing F ilesYou ha ve the option of selec ting loads t o be included in the e xported file .When the Energy Equa tion is enabled in the Ener gy Dialog Box (p.3252 ), you c an cho ose the loads based on the k ind of finit e elemen t analy sis y ou in tend t o under take. By selec ting Structural in the Analy sis list, you c an selec t the f ollowing Structural L oads :Force,Pressur e, and Temp erature. By selec ting Thermal in the Analy sis list, you can selec t the f ollowing Thermal L oads :Temp erature,Heat Flux, and Heat Trans C oeff. These loads ha ve the f ollowing limita tions: •When the Energy Equa tion is disabled , only the Structural L oads options of Force and Pressur e are available . •Loads ar e wr itten only on b oundar y walls when the en tire domain is e xported (tha t is, if no Surfaces are selec ted). Imp ortant For non-sta tionar y reference zones , all the v elocities ar e exported t o I-deas U niversal as v e- locities r elative to the selec ted r eference zone . See the inf ormational not e in Data Ex- plor er F iles (p.617) for fur ther details . Click the Write... butt on t o sa ve the file , using the Selec t File dialo g box. A single file is wr itten c on- taining c oordina tes, connec tivit y, optional loads , zone gr oups , velocity, and selec ted sc alars . You ha ve the option of e xporting da ta a t sp ecified in tervals dur ing a tr ansien t calcula tion thr ough the Automa tic E xport dialo g box. See Exporting D ata D uring a Transien t Calcula tion (p.627) for the c omplet e details . 3.13.13. NASTR AN F iles Selec t NASTR AN from the File Type drop-do wn list. Selec t the sur face(s) c ontaining the da ta you w ant to export in the Surfaces list. If you do not selec t an y sur faces, the en tire domain is e xported.You c an specify which sc alars y ou w ant in the Quan tities list. Note If you ar e exporting da ta on a p olyhedr al mesh, only z one sur faces will b e available f or se- lection (no v olumetr ic da ta or user-defined sur faces). You ha ve the option of selec ting loads t o be included in the e xported file .When the Energy Equa tion is enabled in the Ener gy Dialog Box (p.3252 ), you c an cho ose the loads based on the k ind of finit e elemen t analy sis y ou in tend t o under take. By selec ting Structural in the Analy sis list, you c an selec t the f ollowing Structural L oads :Force,Pressur e, and Temp erature. By selec ting Thermal in the Analy sis list, you can selec t the f ollowing Thermal L oads :Temp erature,Heat Flux, and Heat Trans C oeff. These loads ha ve the f ollowing limita tions : •When the Energy Equa tion is disabled , only the Structural L oads options of Force and Pressur e are available . •Loads ar e wr itten only on b oundar y walls when the en tire domain is e xported (tha t is, if no Surfaces are selec ted). 623Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Exporting S olution D ata af ter a C alcula tionClick the Write... butt on t o sa ve the file , using the Selec t File dialo g box. A single file (f or e xample , file.bdf ) is wr itten c ontaining c oordina tes, connec tivit y, optional loads , zone gr oups , and v elocity. Pressur e is wr itten as PLOAD4 , and hea t flux is wr itten as QHBDYE data. If you selec t wall z ones in the Surfaces list, nodal f orces ar e wr itten f or the w alls.When da ta is wr itten f or the hea t transf er coefficien t, it is based on the w all fac es rather than the no des. You ha ve the option of e xporting da ta a t sp ecified in tervals dur ing a tr ansien t calcula tion thr ough the Automa tic E xport dialo g box. For details , see Exporting D ata D uring a Transien t Calcula tion (p.627). 3.13.14. PATRAN F iles Selec t PATRAN from the File Type drop-do wn list. Selec t the sur face(s) f or which y ou w ant to wr ite data in the Surfaces list. If you do not selec t an y sur faces, the en tire domain is e xported.You c an specify which sc alars y ou w ant in the Quan tities list. You ha ve the option of selec ting loads t o be included in the e xported file .When the Energy Equa tion is enabled in the Ener gy Dialog Box (p.3252 ), you c an cho ose the loads based on the k ind of finit e elemen t analy sis y ou in tend t o under take. By selec ting Structural in the Analy sis list, you c an selec t the f ollowing Structural L oads :Force,Pressur e, and Temp erature. By selec ting Thermal in the Analy sis list, you can selec t the f ollowing Thermal L oads :Temp erature,Heat Flux, and Heat Trans C oeff. These loads ha ve the f ollowing limita tions : •When the Energy Equa tion is disabled , only the Structural L oads options of Force and Pressur e are available . •Loads ar e wr itten only on b oundar y walls when the en tire domain is e xported (tha t is, if no Surfaces are selec ted). Click the Write... butt on t o sa ve the file , using the Selec t File dialo g box. A neutr al file (f or e xample , file.out ) is wr itten c ontaining c oordina tes, connec tivit y, optional loads , zone gr oups , velocity, and selec ted sc alars . Pressur e is wr itten as a distr ibut ed load . If wall z ones ar e selec ted in the Surfaces list, nodal f orces ar e wr itten f or the w alls.The P ATRAN r esult t empla te file (f or e xample ,file.res_tmpl ) is wr itten, which lists the sc alars pr esen t in the no dal r esult file (f or e xample ,file.rst ). You ha ve the option of e xporting da ta a t sp ecified in tervals dur ing a tr ansien t calcula tion thr ough the Automa tic E xport dialo g box. For details , see Exporting D ata D uring a Transien t Calcula tion (p.627). 3.13.15. TAITherm F iles The option t o export a TAITherm file t ype is a vailable only when the Energy Equa tion is enabled in the Ener gy Dialog Box (p.3252 ). Selec t TAITherm from the File Type drop-do wn list and selec t the surface(s) f or which y ou w ant to wr ite da ta in the Surfaces list. If no sur faces ar e selec ted, the en tire domain is e xported. If the mesh c ontains p olyhedr al cells, ANSY S Fluen t will e xport only b oundar y data. No volume da ta will b e exported. Selec t the metho d of wr iting the hea t transf er coefficien t (Heat Transf er C oefficien t), which c an b e Flux B ased or, if a turbulenc e mo del is enabled ,Wall F unc tion based .The flux-based hea t transf er coefficien t is c alcula ted using Equa tion 7.123 (p.995). If no turbulenc e mo del is enabled , the w all- func tion based hea t transf er coefficien t is c alcula ted as , wher e is the ther mal c onduc tivit y, and is the c ell heigh t of the w all-adjac ent cell. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 624Reading and Writing F ilesClick the Write... butt on t o sa ve the file , using the Selec t File dialo g box. A P ATRAN neutr al file (f or example ,file.neu ) is wr itten c ontaining elemen t velocity comp onen ts (tha t is, the elemen t tha t is just t ouching the w all), hea t transf er coefficien ts, and t emp eratures of the w all for an y selec ted w all surface. If the w all is one-sided , the da ta is wr itten f or one side of the w all. If the w all is t wo-sided (a wall-w all shado w pair), the v alues ar e wr itten only f or the or iginal w all fac e, not f or the shado w fac e (which is a duplic ate). You ha ve the option of e xporting da ta a t sp ecified in tervals dur ing a tr ansien t calcula tion thr ough the Automa tic E xport dialo g box. See Exporting D ata D uring a Transien t Calcula tion (p.627) for the c omplet e details . Note If no turbulenc e mo del is enabled , the Wall F unc tion based H eat Transf er C oefficien t is equal t o k/h, wher e k is the ther mal c onduc tivit y, and h is the c ell heigh t of the w all-adjac ent cell. 3.13.16. Tecplot F iles Selec t Tecplot from the File Type drop-do wn list and cho ose the sur face(s) f or which y ou w ant to write da ta in the Surfaces list. If no sur faces ar e selec ted, the da ta is wr itten f or the en tire domain. Selec t the v ariable(s) f or which da ta is t o be sa ved in the Quan tities list. Click the Write... butt on t o sa ve the file , using the Selec t File dialo g box. A single file is wr itten c on- taining the c oordina tes and sc alar func tions in the appr opriate tabular f ormat. Imp ortant •The utilit y fe2ram can imp ort Tecplot files only in FEPOINT format. •If you in tend t o postpr ocess ANSY S Fluen t da ta with Tecplot , you c an either e xport da ta fr om ANSY S Fluen t and imp ort it in to Tecplot , or use the Tecplot ANSY S Fluen t Data Loader included with y our Tecplot distr ibution. The da ta loader r eads na tive ANSY S Fluen t case and da ta files directly. If you ar e interested in this option, contact Tecplot , Inc. for assistanc e or visit www .tecplot.c om. You ha ve the option of e xporting da ta a t sp ecified in tervals dur ing a tr ansien t calcula tion thr ough the Automa tic E xport dialo g box. See Exporting D ata D uring a Transien t Calcula tion (p.627) for the c omplet e details . 3.14. Exporting S tead y-State Particle Hist ory Data Particle hist ory da ta can b e exported f or st eady-sta te solutions or f or single tr ansien t par ticle st eps b y selec ting the Particle Hist ory Data... option under the File/E xport ribbon tab and p erforming the steps descr ibed in this sec tion. For details ab out e xporting par ticle hist ory da ta aut oma tically dur ing transien t simula tions , see Creating A utoma tic Exp ort Definitions f or Transien t Particle Hist ory Data (p.631). File → Export → Particle Hist ory Data... 625Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Exporting S teady-State Particle Hist ory DataFigur e 3.7: The E xport Particle Hist ory Data D ialo g Box 1.Specify the File Type you w ant to export by selec ting one of the f ollowing: •CFD-P ost for the CFD-P ost c ompa tible f ormat •FieldVie w for the FIELD VIEW format •EnSight for the EnS ight format •Geometr y for the .ibl format (not a vailable when Unstead y Particle Track ing is enabled in the Discr ete Phase M odel dialo g box) Imp ortant If you plan t o export par ticle da ta to EnS ight, you should first v erify tha t you ha ve alr eady written the files asso ciated with the EnS ight Case G old file t ype by using the File/E x- port/Solution D ata... ribbon tab option (see EnSight Case G old F iles (p.618)). Selec t the pr edefined injec tions tha t are the sour ce of the par ticles fr om the Injec tions selec tion list. See Creating and M odifying Injec tions (p.1966 ) for details ab out cr eating injec tions . 2.Selec t the par ticle v ariables c ontained in the e xport file b y click ing the Exported P article Variables ... butt on and selec ting the v ariables app earing in the Rep orting Variables dialo g box (Figur e 24.50: The Reporting Variables D ialog Box (p.2046 )), as descr ibed in Reporting of C urrent Positions f or U nsteady Tracking (p.2048 ). Note tha t although the v ariable Particle Residenc e Time does not app ear in the Available Particle Variables selec tion list , it is alw ays exported. 3.If you ha ve added the Color b y variable in the Rep orting Variables dialo g box, selec t an appr opriate categor y and v ariable under Quan tity for the par ticle da ta to be exported. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 626Reading and Writing F iles4.If your e xported par ticle hist ory file is t oo lar ge t o postpr ocess b ecause ther e are too man y tracks or par ticles written t o the file , you c an r educ e the numb er of par ticle tr acks b y incr easing the Skip value . 5.To control the e xported file siz e, the numb er of p oints of the par ticle tr ajec tories c an b e reduc ed using the Coarsen value .This is only v alid f or st eady-sta te par ticle tr ajec tories. 6.Enter the name (and f older pa th, if you do not w ant it t o be wr itten in the cur rent folder) f or the e xported particle da ta file in the Particle F ile N ame text box. Alternatively, you c an sp ecify it thr ough the Selec t File dialo g box, which is op ened b y click ing the Browse... butt on. 7.If you selec ted EnSight under File Type, you should sp ecify the EnSight Encas F ile N ame . Use the Browse... butt on t o selec t the .encas file tha t was cr eated when y ou e xported the file with the File/E xport/Solution Data... ribbon tab option. The selec ted file will b e mo dified and r enamed as a new file tha t contains inf orm- ation ab out all of the r elated par ticle files tha t are gener ated dur ing the e xport process (including geometr y, velocity, scalars , par ticle and par ticle sc alar files). The name of the new file will b e the r oot of the or iginal file with .new app ended t o it (f or e xample , if test.encas is selec ted, a file named test.new.encas will b e wr itten). It is this new file tha t should b e read in to EnS ight. If you do not sp ecify a EnSight Encas F ile N ame , then y ou must cr eate an appr opriate .encas file manually . 8.If you selec ted EnSight under File Type, and y ou ar e exporting st eady-sta te par ticle tr acks , enter the Numb er of P article Time S teps. 9.Click Write to export the par ticle hist ory da ta. If you selec ted EnSight under File Type, data files will b e written in b oth .mpg and .mscl formats. 10.Click Close to close the dialo g box. 3.15. Exporting D ata D uring a Transien t Calcula tion Before you r un a tr ansien t flo w solution, you c an set up the c ase file so tha t solution da ta and par ticle history da ta is e xported as the c alcula tion pr ogresses .This is acc omplished b y creating aut oma tic e xport definitions using the Calcula tion A ctivities Task P age (p.3626 ) (Figur e 3.8: The C alcula tion A ctivities Task Page (p.628)), as descr ibed in the f ollowing sec tions . 627Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Exporting D ata D uring a Transien t Calcula tionFigur e 3.8: The C alcula tion A ctivities Task P age The names of the aut oma tic e xport definitions y ou cr eate ar e displa yed in the Automa tic E xport selec tion list, along with the f ormat in which it will b e exported.You c an edit or delet e the definition b y selec ting a definition in the list and click ing the Edit... or Delet e butt on,. For additional inf ormation, see the f ollowing sec tions: 3.15.1. Creating A utoma tic Exp ort Definitions f or Solution D ata Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 628Reading and Writing F iles3.15.2. Creating A utoma tic Exp ort Definitions f or Transien t Particle Hist ory Data 3.15.1. Creating A utoma tic E xport Definitions f or S olution D ata To cr eate an aut oma tic e xport definition f or solution da ta, begin b y mak ing sur e tha t Transien t is se- lected f or Time in the Gener al Task P age (p.3235 ). Next, click the Create butt on under the Automa tic Export selec tion list in the Calcula tion A ctivities task page (a dr op-do wn list will app ear). Selec t Solution D ata E xport... from the dr op-do wn list t o op en the Automa tic E xport dialo g box (Fig- ure 3.9: The A utoma tic Exp ort Dialog Box (p.629)). Figur e 3.9: The A utoma tic E xport Dialo g Box Then p erform the f ollowing st eps: 1.Enter a name f or the aut oma tic e xport definition in the Name text box.This is the name tha t will b e dis- played in the Automa tic E xport selec tion list in the Calcula tion A ctivities task page . 2.Define the da ta to be exported b y mak ing selec tions in the r elevant group b oxes and selec tion lists: File Type,Cell Z ones ,Surfaces,Interior Z one S urfaces,Quan tities ,Analy sis,Structural L oads ,Thermal Loads ,Location ,Delimit er,Format, and Heat Transf er C oefficien t. See ABAQUS F iles (p.614) – Tecplot F iles (p.625) for details ab out the sp ecific options a vailable f or the v arious file t ypes. 3.Set the fr equenc y at which the solution da ta will b e exported dur ing the c alcula tion using the Export Data E very field and sp ecify whether y ou w ant the sa ve rate based on Time S teps or Flow Time . 4.If you selec ted EnSight Case G old from the File Type drop-do wn list , the Separ ate Files f or E ach Time Step option allo ws you t o sp ecify tha t separ ate files ar e wr itten a t the pr escr ibed time st eps.This option is enabled b y default and is the r ecommended pr actice, as it ensur es tha t all of the da ta is not lost if ther e 629Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Exporting D ata D uring a Transien t Calcula tionis a disr uption t o the c alcula tion (f or e xample , from a net work failur e) b efore it is c omplet e. If you cho ose to disable this option, all of the da ta for the .scl1 and .vel files will b e combined in to a single file f or each. 5.If you selec ted CDA T for CFD-P ost and E nSight from the File Type drop-do wn list , by default ANSY S Fluen t will sa ve a c ase (.cas ) file with e very .cdat file (tha t is, at the sp ecified Frequenc y).You c an change the cr iteria for when c ase files ar e sa ved b y disabling the Write Case F ile E very Time option; then, ANSY S Fluen t will sa ve case files acc ording t o the settings sp ecified b y the f ollowing t ext command: file → transient-export → settings → cdat-for-cfd-post-&-ensight By default , the cdat-for-cfd-post-&-ensight text command is set t o sa ve a c ase file only if ANSY S Fluen t det ects tha t the mesh or c ase file has b een mo dified . Note tha t regar dless of the settings , only a single .cst file will b e wr itten when e xporting dur ing a transien t calcula tion. For mor e inf ormation ab out the CDA T for CFD-P ost and E nSight file t ype, refer to CDA T for CFD- Post and EnS ight (p.615). 6.Specify ho w the e xported files will b e named . Every file sa ved will b egin with the char acters en tered in the File N ame text box (not e tha t a file e xtension is not nec essar y).You c an sp ecify a f older pa th if y ou do not w ant it wr itten in the cur rent folder .The File N ame can also b e sp ecified thr ough the Selec t File dialo g box, which is op ened b y click ing the Browse... butt on. Next, mak e a selec tion in the Append F ile N ame with drop-do wn list , to sp ecify tha t the File Name be followed b y either the time st ep or flo w time a t which it w as sa ved. Note tha t this selec tion is not a vailable when e xporting t o EnS ight.When EnSight Case G old is selec ted fr om the File Type drop-do wn list , the time st ep is alw ays app ended if the Separ ate Files f or E ach Time S tep option is enabled; other wise , no digits ar e app ended . When app ending the file name with the flo w time , you c an sp ecify the numb er of decimal plac es that will b e used b y mak ing an en try in the Decimal P laces in F ile N ame text box. By default , six decimal plac es will b e used . 7.Click OK to sa ve the settings f or the aut oma tic e xport definition. For details ab out gener al limita tions f or e xporting solution da ta and the manner in which it is e xported, see Exporting S olution D ata (p.611). Imp ortant •If the files tha t are exported dur ing multiple tr ansien t simula tions ar e to be used as a set , you should r un all of the simula tions on the same pla tform, using the same numb er of pr ocessors . This ensur es tha t all of the files ar e compa tible with each other . Note If you selec ted EnSight Case G old from the File Type drop-do wn list , ANSY S Fluen t do es not supp ort exporting da ta files t o EnS ight dur ing a tr ansien t cal- cula tion in which a new c ell z one or sur face is cr eated af ter the c alcula tion has b egun (as c an b e the c ase f or an in-c ylinder simula tion, for e xample). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 630Reading and Writing F iles3.15.2. Creating A utoma tic E xport Definitions f or Transien t Particle Hist ory Data To cr eate an aut oma tic e xport definition f or par ticle hist ory da ta, begin b y mak ing sur e tha t Unstead y Particle Track ing is selec ted in the Discr ete Phase M odel dialo g box. Next, click the Create butt on under the Automa tic E xport selec tion list in the Calcula tion A ctivities task page (a dr op-do wn list will app ear). Selec t Particle Hist ory Data E xport... from the dr op-do wn list t o op en the Automa tic Particle Hist ory Data E xport dialo g box (Figur e 3.10: The A utoma tic P article Hist ory Data Exp ort Dialog Box (p.631)). Figur e 3.10: The A utoma tic P article Hist ory Data E xport Dialo g Box Then p erform the f ollowing st eps: 1.Enter a name f or the aut oma tic e xport definition in the Name text box.This is the name tha t will b e dis- played in the Automa tic E xport selec tion list in the Calcula tion A ctivities task page . Make sur e tha t the chosen name is not alr eady used f or another Automa tic E xport. 2.Choose the File Type you w ant to export by selec ting one of the f ollowing: •CFD-P ost for the CFD-P ost c ompa tible f ormat •FieldVie w for the FIELD VIEW format •EnSight for the EnS ight format Imp ortant If you plan t o export par ticle da ta to EnS ight, you should first set up an aut oma tic e xport definition so tha t solution da ta is also e xported t o EnS ight dur ing this c alcula tion (see Creating A utoma tic Exp ort Definitions f or S olution D ata (p.629)). As descr ibed in the 631Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Exporting D ata D uring a Transien t Calcula tionsteps tha t follow, some of the settings must c orrespond b etween the t wo aut oma tic export definitions . 3.Selec t the pr edefined injec tions tha t are the sour ce of the par ticles fr om the Injec tions selec tion list. See Creating and M odifying Injec tions (p.1966 ) for details ab out cr eating injec tions . 4.Selec t the par ticle v ariables c ontained in the e xport file b y click ing the Exported P article Variables ... butt on and selec ting the v ariables app earing in the Rep orting Variables dialo g box (Figur e 24.50: The Reporting Variables D ialog Box (p.2046 )), as descr ibed in Reporting of C urrent Positions f or U nsteady Tracking (p.2048 ). Note tha t although the v ariable Particle Residenc e Time does not app ear in the Available Particle Variables selec tion list , it is alw ays exported. 5.If you ha ve added the Color b y variable in the Rep orting Variables dialo g box, selec t an appr opriate categor y and v ariable under Quan tity for the par ticle da ta to be exported. 6.Set the Frequenc y at which the par ticle hist ory da ta will b e exported dur ing the c alcula tion. If you en ter 10 in the Frequenc y text box, for e xample , a file will b e wr itten af ter every 10 time st eps f or tr ansien t flow cases or 10 DPM I terations f or st eady flo w cases . 7.If your e xported par ticle hist ory file is t oo lar ge t o postpr ocess b ecause ther e are too man y tracks or particles wr itten t o the file , you c an r educ e the numb er of par ticle tr acks b y incr easing the Skip value . 8.If you selec ted EnSight Case G old for the File Type, the Separ ate Files f or E ach Time S tep option allo ws you t o sp ecify tha t separ ate files ar e wr itten a t the pr escr ibed time st eps.This option is enabled b y default and is the r ecommended pr actice, as it ensur es tha t all of the da ta is not lost if ther e is a disr uption t o the calcula tion (f or e xample , from a net work failur e) b efore it is c omplet e. If you cho ose t o disable this option, all of the da ta for the .mscl and .mpg files will b e combined in to a single file f or each. Imp ortant The setting f or the Separ ate Files f or E ach Time S tep option should b e the same (tha t is, enabled or disabled) as tha t of the aut oma tic e xport definition y ou set up t o export solution da ta to EnS ight dur ing this c alcula tion. For details , see Creating A utoma tic Exp ort Definitions f or S olution D ata (p.629). 9.Enter the name (and f older pa th, if you do not w ant it t o be wr itten in the cur rent folder) f or the e xported particle da ta file in the Particle F ile N ame text box. Alternatively, you c an sp ecify it thr ough the Selec t File dialo g box, which is op ened b y click ing the Browse... butt on. Make sur e the file name is diff erent from other e xisting Automa tic E xport definitions t o avoid o verwriting da ta. If you selec ted FieldVie w under File Type, you c an wr ite par ticle hist ory da ta for each time st ep to separ ate files b y including the char acter str ing %t in the par ticle file name . At the time of e xport, Fluen t will substitut e %t with the cur rent time st ep.The sa ved files c an b e pr ocessed b y FieldV iew 14 or new er. 10.If you selec ted EnSight under File Type, you should sp ecify the EnSight Encas F ile N ame . Enter the same name (and f older pa th, if nec essar y) tha t you en tered in the File N ame text box when y ou set up the automa tic e xport definition f or e xporting solution da ta to EnS ight dur ing this c alcula tion. (For details , see Creating A utoma tic Exp ort Definitions f or S olution D ata (p.629)).The .encas file cr eated dur ing the solution da ta export will b e mo dified and r enamed as a new file tha t contains inf ormation ab out all of Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 632Reading and Writing F ilesthe r elated par ticle files tha t are gener ated af ter every time st ep dur ing the e xport process (including geometr y, velocity, scalars , par ticle and par ticle sc alar files). The name of the new file will b e the r oot of the or iginal .encas file with .new app ended t o it (f or e xample , if the solution da ta export creates test.encas , a file named test.new.encas will b e wr itten for the par ticle da ta export). It is this new file tha t should b e read in to EnS ight. Imp ortant If you do not sp ecify an EnSight Encas F ile N ame , you will ha ve to manually cr eate an appr opriate .encas file. 11.Click OK to sa ve the settings f or the aut oma tic e xport definition. The par ticle da ta will b e exported as it is gener ated dur ing the tr ansien t calcula tion. If you selec ted EnSight under File Type, data files will b e wr itten in b oth .mpg and .mscl formats. 3.16. Exporting t o ANSY S CFD-P ost You c an use the Export to CFD-P ost dialo g box (Figur e 3.11: The Exp ort to CFD-P ost D ialog Box (p.633)) to export the r esults fr om c ell z ones and/or sur faces to files tha t are compa tible with ANSY S CFD-P ost (and EnS ight). For instr uctions on e xporting v ariables in ANSY S CFD-P ost c ompa tible file f ormat (.cdat ) using this dialo g box, see CDA T for CFD-P ost and EnS ight (p.615). File → Export to CFD-P ost... Figur e 3.11: The E xport to CFD-P ost D ialo g Box 633Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Exporting t o ANSY S CFD-P ostBy default , the Open CFD-P ost option is enabled so tha t the f ollowing ac tions will o ccur af ter the files are exported: 1.A CFD-P ost session op ens aut oma tically. 2.The c ase and .cdat files ar e loaded in CFD-P ost. 3.CFD-P ost displa ys the r esults . If you disable the Open CFD-P ost option, you c an op en CFD-P ost manually and use the Load Results item in the File drop-do wn menu t o load the r esults files . For mor e inf ormation ab out this f eature in CFD-P ost, see the separ ate ANSY S CFD-P ost manual. Note •When e xporting t o CFD-P ost, Fluen t only sa ves a new c ase file if the mesh or c ase has changed sinc e the last time the c ase file w as sa ved, which c onser ves st orage spac e. •CFD-P ost ma y ha ve difficult y reading tr ansien t cases tha t ha ve changing mesh t opology and/or zones added/r emo ved dur ing the simula tion. 3.17. Parallel E xporting t o ANSY S EnSight Using the EnSight Parallel option in the Export dialo g box you c an sa ve Fluen t solution c ase and data files f or p ostpr ocessing in ANSY S EnS ight En terprise (EnS ight in par allel). To setup par allel EnS ight export in F luen t: 1.Ensur e tha t you ar e running F luen t in par allel. This func tionalit y is onl y available when F luent is r unning in par allel. 2.Open the Export dialo g box. File → Export → Solution D ata... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 634Reading and Writing F iles3.Selec t EnSight Case G old from the File Type drop-do wn. 4.Selec t either Node or Cell C enter for the Location wher e the da ta will b e wr itten. 5.Selec t the Format for ho w the da ta will b e sa ved. 6.Enable EnSight Parallel . 7.Selec t either the Cell Z ones or Surfaces tha t you w ant to export. 8.Selec t the Quan tities tha t you w ant to export. 9.Click Write... to sp ecify the lo cation wher e the da ta will b e sa ved. Note that y ou c an also setup f or aut omatic e xporting of solution data using the same st eps as descr ibed above but using the Automatic E xport Dialo g Box (p.3631 ). Imp ortant You c an either e xport solution da ta fr om Cell Z ones or Surfaces, but y ou c annot do b oth at onc e. 3.18. Managing S olution F iles You c an manage y our solution files eff ectively and efficien tly using the Solution F iles dialo g box. Here, you c an selec t previously sa ved files cr eated using the Autosa ve dialo g box and r ead or delet e them. File → Solution F iles ... 635Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Managing S olution F ilesFigur e 3.12: The S olution F iles D ialo g Box The Solution F iles dialo g box (Figur e 3.12: The S olution F iles D ialog Box (p.636)) lists all of the solution files tha t ha ve been aut oma tically sa ved.They are list ed b y iteration numb er or time st ep/flo w time . For the file tha t is cur rently r ead in, the sta tus of current will app ear in the Solution F iles a t list. You can mak e an y of the files in the list cur rent by click ing the Read butt on. Note tha t if mor e than one file is selec ted, the Read butt on is disabled .When an ear lier solution is made cur rent, the solution files tha t were gener ated f or a la ter it eration/time st ep will b e remo ved fr om this list when the c alcula tion c on- tinues . You c an delet e solution files b y selec ting an en try in the list and click ing Delet e. Note tha t a cur rently loaded solution file c annot b e delet ed, however multiple (non-cur rent) files c an b e selec ted and delet ed. If multiple files ar e selec ted and one of those files is a cur rently loaded solution file , click ing Delet e will result in the cur rent solution file b eing sk ipped. You c an click the File N ames ... butt on t o obtain inf ormation ab out the solution files and the pa th of the asso ciated files . When r unning F luen t under Workbench, you c an r ecover the la test c ase and da ta files fr om the sy stem folder (\dp0\FFF\Fluent\ for analy sis sy stem and \dp0\ FLU \Fluent\ for c omp onen t system) b y click ing Rec over M issing S olution... The r ecovered files will app ear in the Solution F iles a t list. You c an use this option when the la test ma tching/c ompa tible case and da ta files ar e missing fr om the Solution F iles a t list. The Solution F iles dialo g box is par ticular ly useful f or reading in files tha t were sa ved dur ing the autosave session, sinc e case and da ta files ma y not nec essar ily ha ve the same file name . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 636Reading and Writing F iles3.19. Mesh-t o-M esh S olution In terpolation ANSY S Fluen t can in terpolate solution da ta for a giv en geometr y from one mesh t o another , allo wing you t o comput e a solution using one mesh (f or e xample , hexahedr al) and then change t o another mesh (for e xample , hybrid) and c ontinue the c alcula tion using the first solution as a star ting p oint. Imp ortant ANSY S Fluen t do es z eroth-or der in terpolation f or in terpolating the solution da ta fr om one mesh t o another . For additional inf ormation, see the f ollowing sec tions: 3.19.1. Performing M esh-t o-M esh S olution In terpolation 3.19.2. Format of the In terpolation F ile 3.19.1. Performing M esh-t o-M esh S olution In terpolation The pr ocedur e for mesh-t o-mesh solution in terpolation is as f ollows: 1.Set up the mo del and c alcula te a solution on the initial mesh. 2.Write an in terpolation file f or the solution da ta to be interpolated on to the new mesh, using the Interpolate Data dialo g box (Figur e 3.13: The In terpolate Data D ialog Box (p.637)). File → Interpolate... Figur e 3.13: The In terpolate D ata D ialo g Box a.Under Options , selec t Write Data. 637Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Mesh-t o-M esh S olution In terpolationb.In the Cell Z ones selec tion list , selec t the c ell z ones f or which y ou w ant to sa ve da ta to be interpolated. Note If your c ase includes b oth fluid and solid z ones , write the da ta for the fluid z ones and the da ta for the solid z ones t o separ ate files . c.Selec t the v ariable(s) f or which y ou w ant to interpolate da ta in the Fields selec tion list. All ANSY S Fluen t solution v ariables ar e available f or in terpolation. d.Selec t the Binar y File check b ox if y ou w ant a binar y interpolation file t o be gener ated. Note Writing a binar y interpolation file is signific antly fast er and r equir es less memor y than wr iting a t ext file . e.Click Write... and sp ecify the in terpolation file name in the r esulting Selec t File dialo g box.The file format is descr ibed in Format of the In terpolation F ile (p.639). 3.Set up a new c ase. a.Read in the new mesh, using the appr opriate ribbon tab it em ( File/Read/ or File/Imp ort/). b.Define the appr opriate mo dels . Imp ortant Enable all of the mo dels tha t were enabled in the or iginal c ase. For e xample , if the ener gy equa tion w as enabled in the or iginal c ase and y ou f orget t o enable it in the new c ase, the t emp erature da ta in the in terpolation file will not b e in terpolated. c.Define the b oundar y conditions , material pr operties, and so on. Imp ortant An alt ernative way to set up the new c ase is t o sa ve the b oundar y conditions fr om the original mo del using the write-settings text command , and then r ead in those boundar y conditions with the new mesh using the read-settings text command . See Reading and Writing B oundar y Conditions (p.596) for fur ther details . 4.Read in the da ta to be interpolated. File → Interpolate... a.Under Options , selec t Read and In terpolate. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 638Reading and Writing F ilesb.In the Cell Z ones list, selec t the c ell z ones f or which y ou w ant to read and in terpolate da ta. If the solution has not b een initializ ed, comput ed, or r ead, all z ones in the Cell Z ones list ar e selec ted b y default , to ensur e tha t no z one r emains without da ta af ter the in terpolation. If all zones alr eady ha ve da ta (fr om initializa tion or a pr eviously c omput ed or r ead solution), selec t a subset of the Cell Z ones to read and in terpolate da ta on to a sp ecific z one (or z ones). c.Click the Read ... butt on and sp ecify the in terpolation file name in the r esulting Selec t File dialo g box. Imp ortant If your c ase includes b oth fluid and solid z ones , the t wo sets of da ta ar e sa ved t o separ ate files . Hence perform these st eps t wice, onc e to in terpolate the da ta for the fluid z ones and onc e to in terpolate the da ta for the solid z ones . 5.Reduc e the under-r elaxa tion fac tors and c alcula te on the new mesh f or a f ew it erations t o avoid sudden changes due t o an y imbalanc e of flux es af ter in terpolation. Then incr ease the under-r elaxa tion fac tors and c omput e a solution on the new mesh. 3.19.2. Format of the In terpolation F ile An example of an in terpolation file is sho wn b elow: 3 2 34800 3 x-velocity pressure y-velocity (-0.068062 -0.0680413 ... The f ormat of the in terpolation file is as f ollows: •The first line is the in terpolation file v ersion. It is 2 for files gener ated using ANSY S Fluen t 12.0 thr ough 14.0,3 for text files gener ated using ANSY S Fluen t 14.5,4 for binar y files gener ated using single pr ecision ANSY S Fluen t 14.5, and 5 for files gener ated using double pr ecision ANSY S Fluen t 14.5. •The sec ond line is the dimension ( 2 or 3). •The thir d line is the t otal numb er of p oints. •The fourth line is the t otal numb er of fields (t emp erature, pressur e, and so on) included . •Starting a t the fif th line is a list of field names .To see a c omplet e list of the field names used b y ANSY S Fluen t, enter the display/contour text command and view the a vailable choic es b y pr essing Enter at the contours of> prompt. The list dep ends on the mo dels tur ned on. •After the field names is a sec tion f or each list of , , and (in 3D) coordina tes for all the da ta p oints. •At the end is a sec tion f or each list of the field v alues a t all the p oints in the same or der as their names .The numb er of c oordina te and field p oints should ma tch the numb er giv en in line 3. 639Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Mesh-t o-M esh S olution In terpolation•For v ersion 3 interpolation files , the sec tions ar e bounded b y “(” and “)”. •For v ersion 4 and 5 interpolation files , the sec tions ar e bounded b y “(” and “\nEnd of B inar y Section 0)” . •The delimit ers help sk ip a sec tion if the asso ciated mo del is not enabled .With v ersion 2 interpolation files (wher e the delimit ers do not e xist), sec tions ma y not b e sk ipped pr operly if the siz e of the field c annot b e determined without enabling the asso ciated mo del. This ma y result in inc orrect interpolation of the sub- sequen t field v ariables . Imp ortant An in terpolation file wr itten with ANSY S Fluen t 14.5 and ab ove is not r eadable in pr ior versions of ANSY S Fluen t. 3.20. Mapping D ata for F luid-S tructure In teraction (FSI) A pplic ations ANSY S Fluen t allo ws you t o map v ariables (f or e xample , temp erature, pressur e) fr om the c ell or fac e zones of an ANSY S Fluen t simula tion on to lo cations asso ciated with a finit e elemen t analy sis (FEA) mesh. The r esults ar e wr itten t o a file f or inclusion in to an FEA simula tion. During this pr ocess, both the or i- ginal and the new mesh c an b e view ed simultaneously . ANSY S Fluen t maps the da ta using z eroth-or der interpolation, and c an wr ite the output file in a v ariety of f ormats. This c apabilit y is useful when solving fluid-str ucture in teraction (FSI) pr oblems , and allo ws you t o perform further analy sis on the solid p ortion of y our mo del using FEA sof tware. Mapping the da ta ma y be preferable t o simply e xporting the ANSY S Fluen t da ta file (as descr ibed in Exporting S olution D ata (p.611)), sinc e the meshes used in CFD analy sis ar e typic ally finer than those used in finit e elemen t analy sis. For additional inf ormation, see the f ollowing sec tions: 3.20.1. FEA F ile F ormats 3.20.2. Using the FSI M apping D ialog Boxes 3.20.1. FEA F ile F ormats The FEA sof tware types tha t are compa tible with ANSY S Fluen t’s FSI mapping c apabilit y include AB AQUS, I-deas , ANSY S, NASTR AN, and P ATRAN. For details ab out the k inds of files tha t can b e read or wr itten during this pr ocess, see Table 3.2: FEA F ile Ex tensions f or FSI M apping (p.640). Table 3.2: FEA F ile E xtensions f or FSI M apping Output F ile Input F ile Type .inp .inp ABAQUS .unv .unv I-deas .cdb .cdb ,.neu ANSY S .bdf .bdf NASTR AN .out .neu ,.out ,.pat PATRAN Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 640Reading and Writing F iles3.20.2. Using the FSI M apping D ialo g Boxes To begin the pr ocess of mapping ANSY S Fluen t da ta, you must first cr eate a mesh file tha t can b e used as the input file in the st eps tha t follow.The r esolution of the mesh should b e appr opriate for y our eventual finit e elemen t analy sis.You ar e free t o use the metho d and pr eprocessor of y our choic e in the cr eation of this file , but the end r esult must c orrespond t o one of the en tries in the Input F ile column of Table 3.2: FEA F ile Ex tensions f or FSI M apping (p.640). When cr eating the input file , not e the f ollowing: •While the input file ma y be sc aled when it is r ead in to ANSY S Fluen t, the v olumes or sur faces on which the data is t o be mapp ed must other wise b e spa tially c oinciden t with their c oun terparts in the ANSY S Fluen t sim- ulation. •ANSY S Fluen t can map v olume and sur face da ta only f or 3D c ases; data mapping is not supp orted f or 2D cases sinc e da ta mapping f or edges is not supp orted. •The input file c an b e only a p ortion of the o verall FEA mo del (tha t is, you c an e xclude the par ts of the model on which y ou ar e not mapping ANSY S Fluen t da ta).When this is the c ase, not e tha t the numb ering of the no des and elemen ts in the input file must ma tch the numb ering of the no des and elemen ts in the complet e file y ou will use f or y our finit e elemen t analy sis. Next, read a c ase file in ANSY S Fluen t and mak e sur e da ta is a vailable f or mapping , either b y running the c alcula tion or b y reading a da ta file . Finally , perform the f ollowing st eps t o gener ate an output file in which the ANSY S Fluen t da ta has been mapp ed t o the mesh of the input file: 1.Open the ANSY S Fluen t dialo g box tha t is appr opriate for the z ones fr om which the da ta is t o be tak en. If the da ta you ar e mapping is fr om a v olume (f or e xample , the c ell z one of a solid r egion), open the Volume FSI M apping dialo g box using the File/FSI M apping/V olume ... ribbon tab it em ( Figur e 3.14: The Volume FSI M apping D ialog Box for C ell Z one D ata (p.642)). If inst ead the da ta is fr om a sur face (for e xample , a fac e boundar y zone), open the Surface FSI M apping dialo g box using the File/FSI M apping/S urface... ribbon tab it em ( Figur e 3.15: The Sur face FSI M apping D ialog Box for Face Zone D ata (p.642)). File → FSI M apping → Volume ... or File → FSI M apping → Surface... 641Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Mapping D ata for Fluid-S tructure Interaction (FSI) A pplic ationsFigur e 3.14: The Volume FSI M apping D ialo g Box for C ell Z one D ata Figur e 3.15: The S urface FSI M apping D ialo g Box for F ace Zone D ata 2.Specify the par amet ers of the input file and r ead it in to ANSY S Fluen t. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 642Reading and Writing F ilesa.Selec t the f ormat of the input file fr om the Type list in the Input F ile group b ox, based on the FEA software with which it is asso ciated.The choic es include: •ABAQUS •I-deas •Mechanic al APDL •NASTR AN •PATRAN For a list of the file e xtensions asso ciated with these t ypes, see the Input F ile c olumn of Table 3.2: FEA F ile Ex tensions f or FSI M apping (p.640). b.Enter the name and e xtension (along with the f older pa th, if it is not in the cur rent folder) of the input file in the FEA F ile text-en try box. Alternatively, you c an sp ecify it thr ough the Selec t File dialo g box, which is op ened b y click ing the Browse... butt on. c.Specify the length units tha t were used in the cr eation of the input file b y mak ing a selec tion fr om the Length U nits drop-do wn menu .This ensur es tha t the input file is sc aled appr opriately r elative to the ANSY S Fluen t file . d.Click the Read butt on t o read the input file in to memor y. Imp ortant Note tha t the input file will only b e held in memor y un til the output file is wr itten, or until the FSI mapping dialo g box is closed . 3.Displa y the meshes so tha t you c an visually v erify tha t the input file is pr operly sc aled and aligned with the ANSY S Fluen t mesh file . a.Make sur e tha t the FEA M esh and Fluen t - M esh options ar e selec ted in the Displa y Options group box. Note tha t you c an disable either of these options if y ou w ant to examine one of the meshes inde- penden tly. b.Click the Displa y butt on t o displa y the meshes in the gr aphics windo w. Imp ortant For the ANSY S Fluen t mesh, only the z ones selec ted in the Fluen t Zones group b ox will be displa yed—in this c ase, the default selec tions . If the default z ones ar e not appr opriate, you should r edispla y the meshes af ter y ou mak e your z one selec tions in a la ter st ep. 4.Specify the t ype of da ta variables t o be mapp ed. a.Selec t either Structural or Thermal in the Analy sis group b ox.Your selec tion should r eflec t the k ind of fur ther analy sis y ou in tend t o pursue , and will det ermine wha t variables ar e available f or mapping . 643Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Mapping D ata for Fluid-S tructure Interaction (FSI) A pplic ationsb.Enable the v ariables y ou w ant to map in the Structural L oads or Thermal L oads group b ox.When mapping v olume da ta, you c an enable only Temp erature.When mapping sur face da ta, you c an enable Force,Pressur e, and Temp erature for str uctural analy sis, or Temp erature,Heat Flux, and Heat Trans Coeff for ther mal analy sis. Imp ortant Note tha t the Energy Equa tion must b e enabled in the Energy dialo g box if y ou w ant to map t emp erature for a str uctural analy sis or an y variable f or a ther mal analy sis. 5.Selec t the z ones tha t contain the da ta to be mapp ed in the Flluen t Zones group b ox.You c an selec t in- dividual z ones in the Cell Z ones or Face Zones selec tion lists , or selec t all z ones of a par ticular t ype in the Zone Type selec tion list. If you mo dify the default selec tions , you should displa y the meshes again, as descr ibed pr eviously . Imp ortant •Note tha t all w all z ones in the Face Zones selec tion list ar e selec ted b y default in the Surface FSI M apping dialo g box, and this includes the shado w w alls cr eated f or two-sided w alls. If your ANSY S Fluen t file c ontains a w all/shado w pair (f or e xample , separ ating a solid z one from a fluid z one), you should mak e sur e tha t only the c orrect wall or shado w of the pair is selec ted. •Inlet z ones do not ha ve hea t transf er coefficien t da ta, and so an y attempts t o map this combina tion will b e ignor ed. 6.Specify the par amet ers of the output file and wr ite it. a.Selec t the f ormat of the output file fr om the Type list in the Output F ile group b ox, based on the software with which y ou plan t o perform your finit e elemen t analy sis.The choic es in this list ar e the same as those f or the input file t ype. Note tha t you c an selec t an output file t ype tha t is diff erent from the input file t ype. For details ab out the file e xtensions asso ciated with the v arious t ypes of output files , see the Output F ile c olumn of Table 3.2: FEA F ile Ex tensions f or FSI M apping (p.640). b.Enter the name (with the f older pa th, if appr opriate) of the output file in the File N ame text-en try box. Alternatively, you c an sp ecify it thr ough the Selec t File dialo g box, which is op ened b y click ing the Browse... butt on. c.To include additional FEA inf ormation lik e no de/elemen t inf ormation in the e xported output file , enable Include FEA M esh. By default , this option is disabled and ther efore, only the selec ted b oundar y con- dition v alues ar e exported. d.When mapping t emp erature for a str uctural analy sis or an y variable f or a ther mal analy sis, mak e a selec tion in the Temp erature Units drop-do wn menu .Table 3.3: Units A ssociated with the Temp erature Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 644Reading and Writing F ilesUnits D rop-D own List S elec tions (p.645) sho ws the units f or the mapp ed v ariables , dep ending on the Temp erature Units selec tion. Table 3.3: Units A ssociated with the Temp erature Units D rop-D own List S elec tions Heat Transf er C oefficien t Heat Flux Temp erature Temp erature Units Selec tion W/ -K W/ K K W/ - °CW/ °CC BTU/ -hr- °F BTU/ -hr°FF e.When mapping the hea t transf er coefficien t for a ther mal analy sis, mak e a selec tion in the HTC Type drop-do wn menu t o det ermine ho w the hea t transf er coefficien t is calcula ted. ref-t emp calcula tes using Equa tion 42.39 (p.3029 ), wher e is the r eference temp erature defined in the Reference Values Task P age (p.3601 ). Note tha t this option has the same definition as the field variable Surface Heat Transf er C oef., as descr ibed in Alphab etical Listing of F ield Variables and Their D efinitions (p.2988 ). cell-t emp calcula tes using the gener al form of Equa tion 42.39 (p.3029 ), but defines as the t emp erature of the c ell adjac ent to the fac e. wall-func-h tc calcula tes using Equa tion 42.57 (p.3037 ). Note tha t this option has the same definition as the field v ariable Wall F unc . Heat Tran. Coef., as descr ibed in Alphab etical Listing of F ield Variables and Their D efinitions (p.2988 ). f.Click Write to wr ite an output file in which the ANSY S Fluen t da ta has b een mapp ed t o the mesh of the input file . The input file will b e released fr om memor y when the output file is wr itten. 3.21. Saving P icture Files Graphic windo w displa ys can b e sa ved in v arious 2D and 3D f ormats (see Choosing the P icture File Format (p.647) for a full listing of the supp orted file t ypes).There can b e sligh t diff erences b etween pictures and the displa yed gr aphics windo ws dep ending on y our settings and har dware, as the pic tures may be gener ated using the in ternal sof tware render er while the gr aphics windo ws ma y use sp ecializ ed graphics har dware for optimum p erformanc e.To elimina te such diff erences and sa ve these files a t the fastest r ate possible , you must f ollow all of the f ollowing b est pr actices: •Run C ortex on a suitable machine with an appr opriate gr aphics c ard and the la test dr ivers (f or details , see the ANSY S websit e). Note tha t you c an assign C ortex to a par ticular machine using the -gui_machine= command line option, or b y selec ting Specify M achine from the Graphics D ispla y M achine list in the Scheduler tab of F luen t Launcher . 645Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Saving P icture Files•Ensur e tha t Cortex / the host pr ocess is r un on a separ ate machine than tha t used f or comput e no de 0. For example , do not include the machine assigned using the -gui_machine option as the first machine in the hosts file / machine list (sp ecified using the -cnf=x command line option). •Do not set the gr aphics dr iver to null ,x11 (for Linux), or msw (for Windo ws). •When sa ving pic ture files , enable the Fast har dcopy option in the Preferenc es dialo g box (under Graphics ). Many sy stems pr ovide a utilit y to “dump ” the c ontents of a gr aphics windo w in to a r aster file .This is gener ally the fast est metho d of gener ating a pic ture (sinc e the sc ene is alr eady render ed in the gr aphics windo w), and guar antees tha t the pic ture is iden tical to the windo w. Note You c an c ontrol the line thick ness in sa ved images b y sp ecifying the Line width setting in Preferenc es, under Save Picture Settings . For additional inf ormation, see the f ollowing sec tions: 3.21.1. Using the S ave Picture Dialog Box 3.21.2. Picture Options f or P ostScr ipt F iles 3.21.1. Using the S ave Picture Dialo g Box To set pic ture par amet ers and sa ve pic ture files , use the Save Picture Dialog Box (p.3676 ) (Figur e 3.16: The Save Picture Dialog Box (p.646)). File → Save Picture... Figur e 3.16: The S ave Picture D ialo g Box Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 646Reading and Writing F ilesFor y our c onvenienc e, this dialo g box ma y also b e op ened using the Save Picture butt on ( ) in the standar d toolbar . The pr ocedur e for sa ving a pic ture file is as f ollows: 1.Choose the pic ture file Format. 2.Set the Color ing. 3.Specify the File Type, if applic able . 4.Define the Resolution , if applic able . 5.Set the appr opriate Options . 6.If you ar e gener ating a windo w dump , specify the Windo w D ump C ommand . 7.(optional) P review the r esult b y click ing Preview. 8.Click the Save... butt on and en ter the file name in the r esulting Selec t File dialo g box. See Automa tic Numb ering of F iles (p.585) for inf ormation on sp ecial f eatures related t o file name sp ecific ation. If you ar e not r eady to sa ve a pic ture but w ant to sa ve the cur rent pic ture settings , click the Apply butt on inst ead of the Save... butt on.The applied settings b ecome the defaults f or subsequen t pic tures. 3.21.1.1. Choosing the P icture File F ormat To cho ose the pic ture file f ormat, selec t one of the f ollowing it ems in the Format list: EPS (Enc apsula ted P ostScr ipt) output is the same as P ostScr ipt output , with the addition of A dob e Documen t Structuring C onventions (v2) sta temen ts. Currently, no pr eview bitmap is included in EPS output. Often, programs tha t imp ort EPS files use the pr eview bitmap t o displa y on-scr een, although the ac tual v ector PostScr ipt inf ormation is used f or pr inting (on a P ostScr ipt de vice).You c an sa ve EPS files in r aster or vector format. JPEG is a c ommon r aster file f ormat. PPM output is a c ommon r aster file f ormat. PostScr ipt is a c ommon v ector file f ormat.You c an also cho ose t o sa ve a P ostScr ipt file in r aster format. TIFF is a c ommon r aster file f ormat. PNG is a c ommon r aster file f ormat. HSF is HOOPS Visualiz e Stream F ormat, a highly-c ompr essible and str eamable 2D/3D file f ormat. 647Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Saving P icture FilesAVZ is the fr ee ANSY S Viewer Format, which is a 3D file f ormat allo wing y ou t o visualiz e, shar e, collab orate, and in teractively manipula te the displa yed objec t. For additional inf ormation on the ANSY S Viewer, refer to ANSY S Viewer U ser's G uide . Limitations for A VZ E xport: •Only mesh fac es (not edges) c an b e displa yed in the ANSY S Viewer. •Contour v alues ma y be displa yed inc orrectly in the ANSY S Viewer, if the Node Values option w as disabled when the .avz file w as sa ved. •Scenes c ontaining multiple c olor maps ma y sho w the c olor maps o verlapping when displa yed in the ANSY S Viewer.You c an r earrange the c olor maps b y dr agging and dr opping them t o diff erent locations in the graphics windo w (t op, bottom, right) in ANSY S Fluen t before sa ving in A VZ f ormat to avoid this o verlap issue . •The ANSY S Viewer has a fix ed siz e for pa thline and par ticle tr ack displa ys tha t ma y not ma tch the e xact settings of the pa thline or par ticle tr ack objec t when it w as sa ved in .avz format in ANSY S Fluen t. •2D plots c annot b e sa ved in .avz format, including r eport plots , residuals , and X Y plots . •Mesh included as par t of a sc ene ma y app ear black, if the tr anspar ency has b een mo dified fr om 0. •Hovering o ver individual v ectors will not displa y their v alues in the ANSY S Viewer.This also applies f or pathline displa ys with the Style set t o either line ,point, or spher e. •The c olor map t ype and pr ecision displa yed in the ANSY S Viewer ma y not ma tch ho w the c olor map app eared when the .avz file w as sa ved in ANSY S Fluen t. VRML is a gr aphics in terchange f ormat tha t allo ws export of 3D geometr ical en tities tha t you c an displa y in the ANSY S Fluen t graphics windo w.This f ormat can c ommonly b e used b y VR sy stems and the 3D geo- metr y can b e view ed and manipula ted in a w eb-br owser gr aphics windo w. Imp ortant Non-geometr ic en tities such as t ext, titles , color bars , and or ientation axis ar e not e x- ported. In addition, most displa y or visibilit y char acteristics set in ANSY S Fluen t, such as ligh ting , shading metho d, transpar ency, face and edge visibilit y, and out er fac e culling , are not e xplicitly e xported but ar e controlled b y the sof tware used t o view the VRML file . Windo w D ump (Linux sy stems only) selec ts a windo w dump op eration f or gener ating the pic ture.With this f ormat, you must sp ecify the appr opriate Windo w D ump C ommand . Imp ortant The ad vantage t o sa ving the anima tion sequenc e using the HSF F ile option is tha t these files ar e highly c ompr essible and c an b e view ed and in teracted with using a “HOOPS Viewer” applic ation on iOS and A ndroid equipp ed de vices.The “HOOPS Viewer” applic ation Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 648Reading and Writing F ilescan b e do wnloaded t o iOS and A ndroid equipp ed de vices fr om the “App S tore” and “Google Play” respectively. An ad vantage t o sa ving the anima tion sequenc e using the PPM Image option is tha t you can use the separ ate pixmap image files f or the cr eation of a single GIF file . GIF file cr eation can b e done quick ly with gr aphics t ools pr ovided b y other thir d-par ty gr aphics pack ages such as ImageM agick, tha t is,animate or convert . For e xample , if y ou sa ve the PPM files star ting with the str ing sequence-2 , and y ou ar e using the ImageM agick sof tware, you c an use the convert command with the -adjoin option t o cr eate a single GIF file out of the sequenc e using the f ollowing c ommand . convert -adjoin sequence-2_00*.ppm sequence2.gif 3.21.1.2. Specifying the C olor Mo de For all f ormats except VRML, HSF , and the windo w dump , specify the t ype of Color ing you w ant to use f or the pic ture file . •Selec t Color for a c olor-sc ale c opy. •Selec t Gray Sc ale for a gr ay-sc ale c opy. •Selec t Mono chrome for a black-and-whit e copy. Most mono chrome P ostScr ipt de vices render Color images in shades of gr ay, but t o ensur e tha t the color r amp is r ender ed as a linear ly-incr easing gr ay ramp , you should selec t Gray Sc ale. 3.21.1.3. Choosing the F ile Type When y ou sa ve an EPS (Enc apsula ted P ostScr ipt) or P ostScr ipt file , cho ose one of the f ollowing under File Type: •A Raster file defines the c olor of each individual pix el in the image . Raster files ha ve a fix ed r esolution. The supp orted r aster formats ar e EPS, JPEG, PPM, PostScr ipt,TIFF , and PNG. •A Vector file defines the gr aphics image as a c ombina tion of geometr ic pr imitiv es lik e lines , polygons , and t ext.Vector files ar e usually sc alable t o an y resolution. The supp orted v ector formats include EPS, PostScr ipt, and VRML. Imp ortant For the quick est pr int time , you c an sa ve vector files f or simple 2D displa ys and r aster files for c omplic ated sc enes . 3.21.1.4. Defining the R esolution For raster pic ture files (tha t is, JPEG, PPM, TIFF , and PNG), you c an c ontrol the r esolution of the pic ture image b y sp ecifying the siz e (in pix els). Set the desir ed Width and Heigh t under Resolution . If the Width and Heigh t are both z ero, the pic ture is gener ated a t the same r esolution as the ac tive graphics windo w.To check the siz e of the ac tive windo w in pix els, click Info in the Displa y Options dialo g box. 649Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Saving P icture FilesFor EPS and P ostScr ipt files , specify the r esolution in dots p er inch ( DPI) inst ead of setting the width and heigh t. 3.21.1.5. Picture O ptions For all pic ture formats except VRML, HSF , and the windo w dump , you c an c ontrol two additional settings under Options : •Specify the or ientation of the pic ture using the Landsc ape Or ientation butt on. If this option is tur ned on, the pic ture is made in landsc ape mo de; other wise , it is made in p ortrait mo de. •Control the f oreground/back ground c olor using the White Back ground option. If this option is enabled , the pic ture is sa ved with a whit e back ground , and (if y ou ar e using the classic c olor scheme f or the graphics windo w) the f oreground c olor is changed t o black. 3.21.2. Picture Options f or P ostScr ipt F iles ANSY S Fluen t provides options tha t allo w you t o sa ve PostScr ipt files tha t can b e pr inted mor e quick ly. The f ollowing options ar e found in the display/set/picture/driver/ post-format text menu: fast-raster enables a r aster file tha t ma y be lar ger than the standar d raster file , but will pr int much mor e quick ly. raster enables the standar d raster file . rle-raster enables a r un-length enc oded r aster file tha t is ab out the same siz e as the standar d raster file , but will print sligh tly mor e quick ly.This is the default file t ype. vector enables the standar d vector file . 3.21.2.1. Windo w D umps (Linux S ystems O nly) If you selec t the Windo w D ump format, the pr ogram uses the sp ecified Windo w D ump C ommand to sa ve the pic ture file . For e xample , if y ou w ant to use xwd to captur e a windo w, set the Windo w Dump C ommand to xwd -id %w > When the dump o ccurs , ANSY S Fluen t aut oma tically in terprets %w to be the ID numb er of the ac tive windo w. When y ou click the Save... butt on, the Selec t File dialo g box app ears . Enter the file name f or the output fr om the windo w dump (f or e xample ,myfile.xwd ). If you ar e planning t o mak e an anima tion, save the windo w dumps in to numb ered files , using the %n variable .To do this , use the Windo w D ump C ommand (xwd -id %w ), but f or the file name in the Selec t File dialo g box en ter myfile%n.xwd . Each time a new windo w dump is cr eated, the value of %n incr eases b y one . So ther e is no need t o tack numb ers on to the pic ture file names manually . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 650Reading and Writing F ilesTo use the ImageM agick anima te pr ogram, saving the files in MIFF f ormat (the na tive ImageM agick format) is mor e efficien t. In such c ases , use the ImageM agick tool import . Set the default Windo w Dump C ommand enter import -window %w Click Save... to op en the Selec t File dialo g box. Specify the output f ormat to be MIFF b y using the .miff suffix a t the end of file name . The windo w dump f eature is b oth, system and gr aphics-dr iver sp ecific .Thus the c ommands a vailable for dumping windo ws dep ends on the par ticular c onfigur ation. The windo w dump c aptur es the windo w exactly as it is displa yed, including r esolution, colors , trans- parency, and so on. For this r eason, all of the inputs tha t control these char acteristics ar e disabled in the Save Picture dialo g box when y ou enable the Windo w D ump format. If you ar e using an 8-bit graphics displa y, use one of the built-in r aster dr ivers (f or e xample ,TIFF) t o gener ate higher-qualit y 24-bit c olor output r ather than dumping the 8-bit windo w. 3.21.2.2. Previewing the P icture Image Before sa ving a pic ture file , you ha ve the option of pr eviewing wha t the sa ved image will lo ok lik e. Click Preview to op en a new windo w tha t will displa y the gr aphics using the cur rent settings .This allows you t o in vestiga te the eff ects of diff erent options in teractively b efore sa ving the final, appr oved picture. 3.22. Setting D ata F ile Q uan tities By default , the inf ormation sa ved in a da ta file includes a standar d set of quan tities tha t were comput ed during the c alcula tion. These quan tities ar e sp ecific ally suitable f or p ostpr ocessing and r estar ting solutions in ANSY S Fluen t. If, however, you plan t o postpr ocess the da ta file in an applic ation other than ANSY S Fluen t (such as ANSY S CFD-P ost) y ou ma y want to include additional quan tities tha t are der ived fr om the standar d quan tities . Note tha t some standar d quan tities ar e also list ed as additional quan tities . If using ANSY S CFD-P ost, wher e a standar d quan tity has a c orresponding en try in the additional quan tity list , the la tter should be selec ted.This is b ecause ANSY S CFD-P ost r equir es tha t some standar d quan tities ar e der ived in a specific f orm. Note Not all standar d quan tities ar e available in CFD-P ost f or p ostpr ocessing . An example of such a quan tity is M ach numb er. The pr ocedur e for gener ating a da ta file with additional quan tities is as f ollows: 1.Read the c ase file (.cas ) for y our simula tion. 2.Initializ e the solution using the Solution Initializa tion Task P age (p.3620 ). 3.Specify the quan tities t o be wr itten in the da ta file , using the Data F ile Q uan tities dialo g box (Fig- ure 3.17: The D ata File Q uan tities D ialog Box (p.652)). 651Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting D ata File Q uantitiesFile → Data F ile Q uan tities ... Figur e 3.17: The D ata F ile Q uan tities D ialo g Box a.View the Standar d Q uan tities list t o see wha t will b e sa ved in the da ta file b y default. Note tha t you cannot deselec t an y of the Standar d Q uan tities . b.Selec t the additional quan tities y ou w ant saved fr om the Additional Q uan tities selec tion list. c.Click OK. 4.Save the c ase file . Note tha t the da ta file quan tities sp ecified in the pr evious st ep will b e sa ved as par t of the c ase file . 5.Run the c alcula tion and sa ve the da ta file .This c an b e done as separ ate steps, or as one st ep if y ou ha ve selec ted the aut oma tic sa ving of da ta files via the Calcula tion A ctivities Task P age (p.3626 ). The Data F ile Q uan tities dialo g box can also b e op ened b y click ing the Data F ile Q uan tities ... butt on in the Autosa ve Case/D ata dialo g box. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 652Reading and Writing F iles3.23. The .fluen t File When star ting up , ANSY S Fluen t looks in y our home f older f or an optional file c alled .fluent . If it finds the file , it loads it with the Scheme load func tion. This file c an c ontain Scheme func tions tha t cust omiz e the c ode’s op eration. The .fluent file c an also c ontain TUI c ommands tha t are execut ed via the Scheme func tion ti-menu- load-string . For e xample , if the .fluent file c ontains (ti-menu-load-string "file read-case test.cas") then ANSY S Fluen t will r ead in the c ase file test.cas . For mor e details ab out the func tion ti-menu- load-string , see Text Menu Input fr om C haracter S trings . Imp ortant Another optional file ,.tgrid , if pr esen t, is also loaded a t star t up .This file ma y contain Scheme func tions tha t cust omiz e the op eration of the c ode in meshing mo de.When b oth the .fluent and .tgrid files ar e pr esen t, the .tgrid file will b e loaded first , followed by the .fluent file, when the solution mo de is launched . Hence, the func tions in the .fluent file will tak e pr ecedenc e over those in the .tgrid file f or the solution mo de. The .fluent file is not loaded aut oma tically when swit ching t o solution mo de fr om meshing mo de.You will need t o load the file separ ately using the Scheme load func tion, if needed . 653Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.The .fluen t FileRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 654Chapt er 4: Unit S ystems This chapt er descr ibes the units used in ANSY S Fluen t and ho w you c an c ontrol them. Information is organiz ed in to the f ollowing sec tions: 4.1. Restrictions on U nits 4.2. Units in M esh F iles 4.3. Built-In U nit S ystems in ANSY S Fluen t 4.4. Customizing U nits ANSY S Fluen t enables y ou t o work in an y unit sy stem, including inc onsist ent units .Thus, for e xample , you ma y work in B ritish units with hea t input in Watts or y ou ma y work in SI units with length defined in inches .This is acc omplished b y pr oviding ANSY S Fluen t with a c orrect set of c onversion fac tors between the units y ou w ant to use and the standar d SI unit sy stem tha t is used in ternally b y the solv er. ANSY S Fluen t uses these c onversion fac tors f or input and output , internally st oring all par amet ers and performing all c alcula tions in SI units . Both solv ers alw ays pr ompt y ou f or the units r equir ed f or all di- mensional inputs . Units c an b e alt ered par t-way thr ough a pr oblem setup and/or af ter y ou ha ve complet ed y our c alcula tion. If you ha ve en tered some par amet ers in SI units and then y ou swit ch t o British, all of y our pr evious inputs (and the default pr ompts) ar e converted t o the new unit sy stem. If you ha ve complet ed a simula tion in SI units but y ou w ould lik e to report the r esults in an y other units , you c an alt er the unit sy stem and ANSY S Fluen t will c onvert all of the pr oblem da ta to the new unit sy stem when r esults ar e displa yed. As not ed ab ove, all pr oblem inputs and r esults ar e stored in SI units in ternally .This means tha t the paramet ers st ored in the c ase and da ta files ar e in SI units . ANSY S Fluen t simply c onverts these v alues to your unit sy stem a t the in terface level. 4.1. Restr ictions on U nits It is imp ortant to not e tha t the units f or some inputs in ANSY S Fluen t are diff erent from the units used for the r est of the pr oblem setup . •You must alw ays define the f ollowing in SI units , regar dless of the unit sy stem y ou ar e using: –Boundar y pr ofiles (see Profiles (p.1051 )) –Source terms (see Defining M ass, Momen tum, Ener gy, and O ther S ources (p.908)) –Custom field func tions (see Custom F ield F unctions (p.3038 )) –Data in e xternally-cr eated X Y plot files (see XY Plots of F ile D ata (p.2869 )) –User-defined func tions (S ee the Fluen t Customiza tion M anual for details ab out user-defined func tions .) •If you define a ma terial pr operty by sp ecifying a t emp erature-dep enden t polynomial or piec ewise-p olyno- mial func tion, rememb er tha t temp erature in the func tion is alw ays in units of Kelvin or R ankine. If you ar e using C elsius or Kelvin as y our t emp erature unit , then p olynomial c oefficien t values must b e en tered in terms of Kelvin; if you ar e using F ahrenheit or R ankine as the t emp erature unit , values must b e en tered in 655Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.terms of R ankine. See Defining P roperties U sing Temp erature-Dependen t Functions (p.1095 ) for inf ormation about t emp erature-dep enden t ma terial pr operties. 4.2. Units in M esh F iles Some mesh gener ators allo w you t o define a set of units f or the mesh dimensions . However, when y ou read the mesh in to ANSY S Fluen t, it is alw ays assumed tha t the unit of length is met ers. If this is not true, you must sc ale the mesh, as descr ibed in Scaling the M esh (p.822). 4.3. Built-In U nit S ystems in ANSY S Fluen t ANSY S Fluen t provides f our built-in unit sy stems: British, SI, CGS, and "default" , all of which c an b e se- lected in the Set U nits dialo g box (Figur e 4.1: The S et U nits D ialog Box (p.656)), using the butt ons under the Set A ll to heading .To displa y the Set U nits dialo g box, right-click Gener al and click Units ..., under Setup in the tr ee. Setup → Gener al Units Figur e 4.1: The S et U nits D ialo g Box To cho ose the English Engineer ing standar d for all units , click the british butt on; to selec t the In terna- tional S ystem of units (SI) standar d for all units , click the si butt on; to cho ose the C GS (c entimet er-gr am- second) standar d for all units , click the cgs butt on; and t o retur n to the "default" system, click the default butt on.The default sy stem of units is similar t o the SI sy stem, but uses degr ees inst ead of r adians f or angles . Clicking on one of the butt ons under Set A ll to will immedia tely change the unit sy stem. You can then close the dialo g box if y ou ar e not in terested in cust omizing an y units . Changing the unit sy stem in the Set U nits dialo g box causes all futur e inputs tha t ha ve units t o be based on the newly selec ted unit sy stem. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 656Unit S ystems4.4. Customizing U nits If you w ould lik e a mix ed unit sy stem, or an y unit sy stem diff erent from the f our supplied b y ANSY S Fluen t (and descr ibed in Built-In U nit S ystems in ANSY S Fluen t (p.656)), you c an use the Set U nits dialo g box (Figur e 4.1: The S et U nits D ialog Box (p.656)) to selec t an a vailable unit or sp ecify y our o wn unit name and c onversion fac tor for each quan tity. For additional inf ormation, see the f ollowing sec tions: 4.4.1. Listing C urrent Units 4.4.2. Changing the U nits f or a Q uantity 4.4.3. Defining a N ew U nit 4.4.1. Listing C urrent Units Before cust omizing units f or one or mor e quan tities , you ma y want to list the cur rent units .You c an do this b y click ing the List butt on a t the b ottom of the Set U nits dialo g box. ANSY S Fluen t will pr int out a list (in the t ext windo w) c ontaining all quan tities and their cur rent units , conversion fac tors, and offsets . 4.4.2. Changing the U nits f or a Q uan tity ANSY S Fluen t will enable y ou t o mo dify the units f or individual quan tities .This is useful f or pr oblems in which y ou w ant to use one of the built-in unit sy stems , but y ou w ant to change the units f or one quan tity (or f or a f ew). For e xample , you ma y want to use SI units f or y our pr oblem, but the dimensions of the geometr y are giv en in inches .You c an selec t the SI unit sy stem, and then change the unit of length fr om met ers t o inches . To change the units f or a par ticular quan tity, you will f ollow these t wo steps: 1. Selec t the quan tity in the Quan tities list (the y are arranged in alphab etical or der). 2. Choose a new unit fr om those tha t are available in the Units list. For the e xample cit ed ab ove, you w ould cho ose length in the Quan tities list, and then selec t in in the Units list. The Factor will aut oma tically b e up dated t o sho w 0.0254 met ers/inch. (See Figur e 4.1: The Set U nits D ialog Box (p.656).) If ther e was a nonz ero off set f or the new unit , the Offset field w ould also b e up dated. For e xample , if y ou w ere using SI units but w anted t o define t emp erature in C elsius instead of Kelvin, you w ould selec t temp erature in the Quan tities list and c in the Units list. The Factor would change t o 1, and the Offset would change t o 273.15. Onc e you ha ve selec ted the quan tity and the new unit , no fur ther ac tion is needed , unless y ou w ant to change the units f or another quan tity by following the same pr ocedur e. 4.4.3. Defining a N ew U nit To cr eate a new unit t o be used f or a par ticular quan tity, you will f ollow the pr ocedur e below: 1. In the Set U nits dialo g box, selec t the quan tity in the Quan tities list. 2. Click the New... butt on and the Define U nit dialo g box (Figur e 4.2: The D efine U nit D ialog Box (p.658)) will op en. In this dialo g box, the selec ted quan tity will b e sho wn in the Quan tity field . 657Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Customizing U nitsFigur e 4.2: The D efine U nit D ialo g Box 3. Enter the name of y our new unit in the Unit field , the c onversion fac tor in the Factor field , and the off set in the Offset field . 4. Click OK in the Define U nit dialo g box, and the new unit will app ear in the Set U nits dialo g box. For e xample , if y ou w ant to use hours as the unit of time , selec t time in the Quan tities list in the Set Units dialo g box and click the New... butt on. In the r esulting Define U nit dialo g box, enter hr for the Unit and 3600 for the Factor, as in Figur e 4.2: The D efine U nit D ialog Box (p.658).Then click OK. The new unit hr will app ear in the Units list in the Set U nits dialo g box, and it will b e selec ted. 4.4.3.1. Determining the C onversion F actor The c onversion fac tor y ou sp ecify ( Factor in the Define U nit dialo g box) tells ANSY S Fluen t the numb er to multiply b y to obtain the SI unit v alue fr om y our cust omiz ed unit v alue .Thus the c onversion factor should ha ve the f orm SI units/cust om units . For e xample , if y ou w ant the unit of length t o be inches , you should en ter a c onversion fac tor of 0.0254 met ers/inch. If you w ant the unit of v elocity to be feet/min, you c an det ermine the c onversion fac tor b y using the f ollowing equa tion: (4.1) You should en ter a c onversion fac tor of 0.0051, which is equal t o 0.3048/60. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 658Unit S ystemsChapt er 5: Fluen t Expressions L anguage 5.1. Introduc tion t o Expressions The F luen t Expr ession Language is an in terpreted, declar ative language based on P ython, tha t enables you t o: •Specify c omple x boundar y conditions and sour ce terms with r espect to time , iteration numb er, position, and solution v ariables . •Specify v arious mo del and solv er settings in t erms of time or it eration. 5.1.1. Expression S yntax An expression is a str ing r epresen ting a c ombina tion of v alues , variables , operators, and func tion c alls that retur ns a v alue when e valua ted with appr opriate values f or the v ariables . For e xample:Vmax*(5.0*exp(-t-0.3 [s]/2.8 [s])) The f ollowing sec tions c over the basic elemen ts of pr oper e xpression syn tax: 5.1.1.1. Expr ession D ata Types 5.1.1.2. Expr ession Values 5.1.1.3. Expr ession Op erations and F unctions 5.1.1.1. Expr ession D ata Types The e valua ted r esult of an e xpression c an b e a r eal numb er, a b oolean, a real field or a b oolean field . For e xample ,2*StaticPressure evalua tes to a r eal field when c omput ed on a z one .Whereas, average(2*StaticPressure, ["inlet"]) evalua tes to a single r eal v alues . Note Cell r egist ers e valua te as b oolean. 5.1.1.2. Expr ession Values Values c an b e real numb ers (f or e xample ,1.0e-3 ), integers (f or e xample , -10, 5, 37), booleans (tr ue or false), or quan tities . Quan tities ar e real numb ers with units asso ciated.The syn tax supp orted f or quan tities is [ ] , for e xample ,2324.0 [Pa kg^-3 s] .The unit sp ecific ation is based on CFX ( Units S yntax in the CFX-P re User's G uide ). 659Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.5.1.1.3. Expr ession O perations and F unc tions All of the f ollowing ma thema tical func tions tak e inputs in the f orm of an e xpression tha t evalua tes to a r eal numb er or a r eal field and r etur n a r eal numb er or r eal field: Table 5.1: Op erations and F unc tions Func tion Descr iption +,-,*,/,** (power),>,>=,<,<=,==,!= Operators AND(, , …) Conditional IF(, , ) NOT() OR(, , …) XOR() acosh() Hyperbolic asinh() atanh() cosh() sinh() tanh() abs() Mathema tical ceil() exp() floor() log() log10() max(, , …) min(,, …) mod(, ) round() sqrt() trunc() Area([, , …]) Reduc tion Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 660Fluen t Expr essions LanguageFunc tion Descr iption Average(, [, , …], Weight=None|"Area"|Volume") Maximum(, [, , …]) Minimum(, [, , …]) Sum(, [, , …], Weight=None|"Area"|Volume") Volume([, , …]) acos() Trigonometr ic asin() atan() atan2(, ) cos() sin() tan() Operations Comp onen ts of v ectors c an b e acc essed with the .x,.y, and the .z suffix es; magnitude c an b e ac- cessed with the .mag suffix. Imp ortant Do not use multiple c ompar ison op erators within a single e xpression, as the op eration will not w ork as in tended . For e xample ,400[K]>--> StaticTemperature > 300[K] will not w ork.To acc omplish this e xpression, use AND(StaticTemperature>300[K], StaticTemperature<400[K]) . IF Stat ements The IF(, , ) func tion r etur ns the if is tr ue, else it r etur ns the . Any of the ar gumen ts can b e fields .The t ype and unit dimension of and must b e the same . OR Stat ements OR(, ) retur ns tr ue if an y of the c onditions (an y of which c an b e a b oolean field) r etur ns tr ue. 661Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Introduction t o Expr essionsAND Stat ements AND(, ) retur ns tr ue if all of the c onditions (an y of which c an b e a b oolean field) r etur ns tr ue. 5.1.2. Units Valida tion Expr essions ar e valida ted t o ensur e the y ha ve consist ent unit t ypes. For e xample , Fluen t flags 1 [cm] + TotalPressure because c entimet ers ar e not units of pr essur e. Note tha t units c an still b e pr ovided in diff erent unit sy stems , for e xample ,1 [atm] + 200 [Pa] . 5.2. Expression S our ces Expr ession sour ces ar e the v ariables tha t can b e used in e xpressions . 5.2.1. Field Variables 5.2.2. Solution Variables 5.2.3. Scien tific C onstan ts 5.2.4. Aliases 5.2.1. Field Variables A subset of the F luen t postpr ocessing field v ariables ar e available f or use in e xpressions . See Appendix: Supp orted F ield Variables (p.679) for a listing of all the a vailable field v ariables . 5.2.2. Solution Variables The f ollowing solution v ariables ar e available: Table 5.2: Solution Variables Descr iption Variable Current time* Time *In st eady sta te, time evalua tes as 0, unless the c ase w as run in transien t, then swit ched t o steady state, in which c ase it will e valua te as the latest time fr om the transien t run. Current time st ep* Timestep *In st eady sta te, timest ep e valua tes as 0, unless the c ase w as run in tr ansien t, then swit ched t o steady state, in which c ase it Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 662Fluen t Expr essions LanguageDescr iption Variable will e valua te as the latest timest ep fr om the tr ansien t run. Current time st ep siz e* DeltaTime *In st eady sta te, delta time e valua tes as 0, unless the c ase w as run in tr ansien t, then swit ched t o steady state, in which c ase it will e valua te as the latest delta time fr om the tr ansien t run. Global it eration c oun t Iteration 5.2.3. Scien tific C onstan ts Table 5.3: Scien tific C onstan ts Value Descr iption Variable 3.14159265358979323846 Pi PI 2.71828182845904523536 e (base of the na tural lo garithm) e 8.314472 [ J K^-1 mol^-1] Gas c onstan t R 6.02214199e23 [mol^-1] Avogadr o's numb er avogadro 1.3806503 [ J K^-1] Boltzmann c onstan t boltzmann 2.99792458e8 [m s^-1] Ligh t velocity clight 1.60217653e-19 [A s] Electron char ge echarge 9.8066502 [m s^-2] Acceleration due t o gr avity g 6.62606876e-34 [ J s] Planck's c onstan t planck 5.670400e-08 [ W m^-2 K^-2] Stephan-B oltzmann c onstan t stephan 4.0*PI*1.0e-7 [N A^-2] Magnetic p ermeabilit y mupermo 1./(cligh t*cligh t*mup ermo) Electric constan t epspermo 5.2.4. Aliases Aliases pr ovide simplified syn tax t o acc ess fr equen tly used v ariables . Table 5.4: Aliases Alias t o Variable Position.x x Position.y y Position.z z Velocity.x u 663Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Expr ession S ourcesAlias t o Variable Velocity.y v Velocity.z w Time* t *In st eady sta te, time evalua tes as 0, unless the c ase w as run in transien t, then swit ched t o steady state, in which c ase it will e valua te as the latest time fr om the transien t run. DeltaT ime* dt *In st eady sta te, delta time e valua tes as 0, unless the c ase w as run in tr ansien t, then swit ched t o steady state, in which c ase it will e valua te as the latest delta time fr om the tr ansien t run. Global it eration c oun t iter StaticTemp erature T StaticPressur e P MassF raction mf 5.3. Creating and U sing E xpressions There ar e two ways tha t you c an cr eate expressions in ANSY S Fluen t.The first w ay is b y creating an expression dir ectly in the field wher e it will b e applied .The sec ond is b y creating a named e xpression, which c an b e reused a t multiple lo cations .These t wo formats ar e discussed in the f ollowing sec tions: 5.3.1. Directly A pplied Expr essions 5.3.2. Named Expr essions 5.3.3. Context Specific ation Imp ortant Be careful t o avoid situa tions wher e you ar e creating a cir cular dep endenc y for a field or property. For e xample , setting the Velocity M agnitude field of a v elocity inlet t o Velo- city.mag , without sp ecifying a v alue f or the v elocity magnitude elsewher e, results in a 0- value f or the v elocity magnitude . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 664Fluen t Expr essions Language5.3.1. Directly A pplied E xpressions You c an use e xpressions a t boundar y and c ell z one c onditions a t fields and pr operties wher e pr ofiles and par amet ers c an also b e defined . Expr essions c an also b e used a t most other non-c ell z one or boundar y condition lo cations wher e par amet ers c an b e defined . To define an e xpression f or a b oundar y or c ell z one c ondition: 1.Open the dialo g box for the b oundar y/cell z one wher e you w ant to create an e xpression. For e xample , the Velocity Inlet dialo g box. 2.Click the dr op-do wn ar row to the r ight of the field tha t you w ould lik e to define using an e xpression and selec t expression . 3.You c an en ter your e xpression dir ectly in the t ext field .ANSY S Fluent pr ovides messaging r egar ding the validit y of the e xpression as so on as y ou b egin ent ering it . Alternatively, you c an click to op en a bigger edit or (Figur e 5.1: The Expr ession E ditor D ialog Box (p.666)). 665Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Creating and U sing Expr essionsFigur e 5.1: The E xpression E ditor D ialo g Box Expr essions in the C onsole You c an sp ecify e xpressions f or settings thr ough the t ext user in terface (C onsole). To do so , enter a string inst ead of a r eal v alue t o sp ecify a setting as an e xpression. For e xample: 5.3.2. Named E xpressions You c an cr eate named e xpressions thr ough the gr aphic al user in terface (GUI) via the Tree. Setup → Named E xpressions New... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 666Fluen t Expr essions LanguageFigur e 5.2: The E xpression D ialo g Box 1.Provide a Name for the e xpression. The name must star t with a lett er and it ma y contain numb ers and un- dersc ores. Note It ma y cause c onfusion if y ou cr eate named e xpressions with names tha t ma tch e xpression func tions such as "e xp" and "abs". 2.Enter the Definition of the e xpression. You c an use the dr op-do wns t o the r ight of the Definition text box to add func tions , variables , cell r egist ers, constants , report definitions , and e xisting e xpressions t o this e xpression definition. 667Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Creating and U sing Expr essionsAll of the supp orted v ariables ar e list ed in the dr op-do wn list . Note When y ou use cur ly br ackets "{}" t o sp ecify the name of a defined objec t, such as a r eport definition or c ell r egist er, aut oma tic suggestions ar e disabled and y ou must pr ovide the displa y name of tha t objec t. 3.(Optional) A dd a Descr iption of the e xpression. 4.(Optional) Enable Use as par amet er, if you w ant to use the named e xpression as an input par amet er. Refer to Defining and Viewing P aramet ers (p.842) for additional inf ormation on par amet ers. 5.Click OK to create the e xpression. TheUsed In field lists the lo cations wher e the e xpression is used , including other e xpressions . You c an use a named e xpression t o define other e xpressions—b oth inline e xpressions and named expressions . For e xample , a named e xpression with the name Vel_magnitude can b e used t o setup the v elocity magnitude setting of an inlet as f ollows: Note •Expr essions tha t are in use c annot b e delet ed. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 668Fluen t Expr essions Language•You c an cr eate and mo dify named e xpressions thr ough the define/named-expressions/ text command in the c onsole . Imp ortant Expr essions must b e dimensionally c onsist ent.For e xample , you c annot add t wo quantities that ha ve diff erent unit dimensions . Saving and Imp orting N amed E xpr essions You ha ve the option of sa ving some or all of the named e xpressions y ou cr eate to a file f or futur e use . Click Export To File... to cho ose a dir ectory and sa ve your e xpression(s) t o a file . Click Imp ort From F ile... to selec t and load an e xpression file . 5.3.3. Context Specific ation Some v ariables r equir e additional c ontext before the y can b e evalua ted. For e xample ,MassFraction requir es the sp ecies c ontext.Velocity ma y requir e phase c ontext when it is e valua ted in a multiphase simula tion. The c ontext is sp ecified as a k eyword ar gumen t to a func tion c all on the v ariable . For e x- ample ,MassFraction(species="co2", phase="smoke") . 5.4. Expression E xamples The f ollowing ar e a f ew e xamples tha t demonstr ate wh y or wher e you ma y want to use an e xpression and ho w you w ould do so f or these situa tions . 5.4.1. Parabolic Inflo w Profile 5.4.2. Time-V aried P arabolic Inflo w 5.4.3. Controlled Outlet Temp erature 5.4.1. Parabolic Inflo w P rofile The f ollowing e xample sho ws you ho w to define a par abolic inlet pr ofile f or laminar pip e flo w, as shown in Figur e 5.3: Contours of Velocity - P arabolic Inflo w (p.670). In this e xample , the pip e is c entered in the X and Z dir ections and the pip e axis is aligned t o the Y-dir ection. 669Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Expr ession ExamplesFigur e 5.3: Contours of Velocity - P arabolic Inflo w The e xpression f or defining the par abolic inflo w sho wn in Figur e 5.3: Contours of Velocity - P arabolic Inflo w (p.670) is Equa tion 5.1 (p.670), (5.1) Where is the v elocity at the axis , is the r adius of the pip e, and is the lo cal radial coordina te. To fully define this e xample: 1.Create a named e xpression f or the maximum v elocity called umax . Setup → Named E xpressions New... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 670Fluen t Expr essions Languagea.Enter umax for the Name . b.Enter 0.2 [m/s] for the Definition and click OK. 2.Create an e xpression f or the r adius of the pip e. a.Open the Expressions dialo g box by right-click ing Named E xpressions in the outline view tr ee and selec ting New.... b.Enter Radius for the Name . c.Enter sqrt(Area(["in"])/PI) for the Definition ."in" is the name of the inlet b oundar y. PI is the e xpression constant f or P i. d.Click OK to create the named e xpression. 671Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Expr ession Examples3.Create an e xpression f or the lo cal radial pr ofile . a.Open the Expressions dialo g box and en ter radius for the Name . b.Enter sqrt(x**2+z**2) for the Definition .This e xpression uses the squar e root mathematic al e xpression operator. c.Click OK to create the named e xpression. 4.Create an e xpression f or the inlet v elocity pr ofile .This e xpression c ombines the other e xpressions y ou cr eated. a.Open the Expressions dialo g box and en ter upr ofile for the Name . b.Enter umax*(1- (r adius/R adius)**2) for the Definition .You c an use the Expr essions drop-do wn t o the right of the Definition box to add named e xpressions t o your e xpression definition as an alt ernativ e to typing the names manuall y. c.Click OK to create the named e xpression. 5.Assign upr ofile to the v elocity inlet. Setup → Boundar y Conditions → Inlet → in Edit... You c an gr oup the b oundar y conditions b y type to or ganiz e the b oundar ies and r educ e the siz e of the list.This c an b e acc omplished b y right-click ing Boundar y Conditions in the tr ee and selec ting Group By> Zone Type. a.Selec t expression from the dr op-do wn t o the r ight of Velocity M agnitude . b.Enter upr ofile in the Velocity M agnitude field and click OK. 5.4.2. Time-V aried P arabolic Inflo w The f ollowing e xample sho ws you ho w to define a par abolic inlet pr ofile f or laminar pip e flo w tha t varies o ver time (a sine func tion with a p eriod of 10 sec onds). The v elocity pr ofile in this e xample is the same as f or Parabolic Inflo w Profile (p.669) except it is f or a tr ansien t simula tion b ecause the v elocity Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 672Fluen t Expr essions Languagevaries o ver time .Figur e 5.4: Parabolic Inflo w Velocity Over Time (p.673) plots the ar ea w eigh ted a verage of the v elocity magnitude o ver 10 sec onds . Figur e 5.4: Parabolic Inflo w Velocity O ver Time To cr eate an e xpression f or this time-v aried v elocity pr ofile: 1.Define all of the named e xpressions as descr ibed in Parabolic Inflo w Profile (p.669). 2.Create an e xpression f or omega. Setup → Named E xpressions New... 673Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Expr ession Examplesa.Enter omega for the Name . b.Enter 2*PI / (10[s]) for the Definition and click OK. 3.Create an e xpression f or the v elocity pr ofile tha t varies o ver time . a.Open the Expressions dialo g box and en ter upr ofile_tr ansien t for the Name . b.Enter upr ofile*(sin(omega*T ime)*0.1 + 1) for the Definition and click OK. 4.Assign upr ofile_tr ansien t to the v elocity inlet. Setup → Boundar y Conditions → Inlet → in Edit... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 674Fluen t Expr essions LanguageYou c an gr oup the b oundar y conditions b y type to or ganiz e the b oundar ies and r educ e the siz e of the list.This c an b e acc omplished b y right-click ing Boundar y Conditions in the tr ee and selec ting Group By> Zone Type. a.Selec t expression from the dr op-do wn t o the r ight of Velocity M agnitude . b.Enter upr ofile_tr ansien t in the Velocity M agnitude field and click OK. 5.4.3. Controlled Outlet Temp erature The f ollowing e xample sho ws you ho w to dr ive the maximum t emp erature at the outlet t o a tar get temp erature by varying the inlet t emp erature. For this sc enar io, a pip e with laminar flo w has a par t of the w all tha t is hea ted t o 350 Kelvin and a tar get outlet t emp erature of 320 Kelvin ( Figur e 5.5: Pipe Geometr y Color ed b y ID (H eated Wall is G reen) (p.676) sho ws the p ortion of the w all tha t is hea ted). A controller tur ns on e very 10th it eration (st eady-sta te case) and adjusts the inlet t emp erature acc ording to Equa tion 5.2 (p.675). In the other it erations , the c ontroller lea ves the t emp erature unchanged .This is achie ved b y using the c onditional sta temen t giv en in Equa tion 5.3 (p.675).Figur e 5.6: Contours of Temp erature (outlet is closest) (p.676) sho ws the de velop ed t emp erature pr ofile f or this c ase. (5.2) (5.3) is the f ormula used t o adjust the inlet t emp erature, is the cur rent inlet t emp erature, is the tar get t emp erature for the outlet , which is set t o 320 Kelvin, is the maximum temp erature at the outlet , and is a r elaxa tion fac tor. 675Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Expr ession ExamplesFigur e 5.5: Pipe Geometr y Color ed b y ID (H eated Wall is G reen) Figur e 5.6: Contours of Temp erature (outlet is closest) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 676Fluen t Expr essions LanguageFigur e 5.7: Plots of Inlet Temp erature, Average Outlet Temp erature, and M aximum Outlet Temp erature The f ollowing st eps sho w ho w to cr eate the e xpressions used in this e xample: 1.Create a named e xpression f or the initial t emp erature, called TStart. Setup → Named E xpressions New... 677Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Expr ession Examplesa.Enter TStart for the Name . b.Enter 300 [K] for the Definition and click OK. 2.Create an e xpression f or the tar get t emp erature for the outlet , called TTarget, and set it equal t o 320 [K] . Use the same pr ocess that y ou used t o cr eate TStar t. 3.Create an e xpression f or the maximum t emp erature tha t occurs a t the outlet , called TMaxOut .In this e x- pression y ou will b e using a func tion t o det ermine the maximum t emp eratur e. a.Click the Func tions drop-do wn and selec t Reduc tion → Maximum . b.Enter StaticT emp erature for the first field of the func tion and ["out"] for the lo cation. The t otal e x- pression should app ear as Maximum(S taticT emp erature, ["out"]) . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 678Fluen t Expr essions Language4.Create an e xpression f or the cur rent inlet t emp erature, called TInC urrent, and set it equal t o Average(S tat- icTemp erature, ["in"], Weigh t=N one) .Use a similar pr ocess t o what y ou used t o cr eate TMaxO ut, but with selec ting the Average func tion inst ead . 5.Create an e xpression f or the r elaxa tion fac tor, called relax , and set it equal t o 0.9. 6.Create an e xpression f or adjusting the inlet t emp erature, called TAdjust , and set it equal t o TInC urrent + (TTarget - TMaxOut)*r elax . 7.Create an e xpression f or the inlet t emp erature, which will b e called TIn, and set it equal t o IF(it er<5, TStart, IF(mo d(it er+1, 10)==0, TAdjust ,TInC urrent)).Use a similar pr ocess t o what y ou used t o cr eate TMaxO ut, but with selec ting the IF conditional func tion inst ead . 8.Assign TIn to the inlet. Setup → Boundar y Conditions → Inlet → in Edit... a.Selec t expression from the dr op-do wn t o the r ight of Temp erature. b.Enter TIn in the Temp erature field and click OK. 5.5. Appendix: Supp orted F ield Variables Table 5.5: Field Variables Variable (t ype) Descr iption AbsolutePressure (scalar) Absolut e Pressur e AbsoluteIRSolarFlux (scalar) Absolut e IR S olar F lux AbsoluteRadiationFlux (scalar) Absolut e Radia tion F lux AbsoluteVisibleSolarFlux (scalar) Absolut e Visible S olar F lux AbsorptionCoefficient (scalar) Absor ption C oefficien t Accumulated Deformation (scalar) Accumula ted D eformation 679Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Appendix: Supp orted F ield VariablesVariable (t ype) Descr iption AcentricFactor (scalar) Acentric Factor AcousticPower (scalar) Acoustic P ower AcousticPowerLeveldB (scalar) Acoustic P ower L evel (dB) ActiveElementPartition (scalar) Active Cell P artition AdaptionCurvature (scalar) Adaption C urvature AdaptionFunction (scalar) Adaption F unction AdaptionIsoValue (scalar) Adaption I so-V alue AdaptionSpaceGradient (scalar) Adaption S pace Gradien t AdaptionFlameTemperature (scalar) Adaption F lame Temp erature AdjointAp (scalar) Adjoin t Ap AdjointLocalSolutionMaker (scalar) Adjoin t Local Solution M aker ArtificialDissipation (scalar) Artificial D issipa tion ArtificialInterfacialViscosity (scalar) Artificial In terfacial Viscosity AxialVelocity (scalar) Axial Velocity BCDNormalizedVariableU (scalar) BCD N ormaliz ed Variable U BCDNormalizedVariableV (scalar) BCD N ormaliz ed Variable V BCDNormalizedVariableW (scalar) BCD N ormaliz ed Variable W BackgroundSizingFunction (scalar) Background S izing F unction BeamIrradiationFlux (scalar) Beam Ir radia tion F lux BlendingFunctionforGEKO (scalar) Blending F unction f or GEK O BodyForceMagnitude (scalar) Body Force M agnitude BodyForced (vector) Body-Force-d%s BoundaryCellDistance (scalar) Boundar y Cell D istanc e BoundaryVolumeDistance (scalar) Boundar y Volume D istanc e CapillaryPressure (scalar) Capillar y-Pressur e CellAR (scalar) Cell AR CellARDirectional (scalar) Cell AR D irectional CellARRatio (scalar) Cell AR R atio CellARRatioTag (scalar) Cell AR R atio Tag CellBoundaryDistanceMeshSmoothing (scalar) Cell B oundar y Distanc e M esh Smoothing CellBoundaryDistanceOverset (scalar) Cell B oundar y Distanc e Overset CellCFLMultiplier (scalar) Cell CFL M ultiplier CellChildren (scalar) Cell C hildr en CellElementType (scalar) Cell E lemen t Type CellEquiangleSkew (scalar) Cell E quiangle S kew CellEquivolumeSkew (scalar) Cell E quiv olume S kew CellID (scalar) Cell ID Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 680Fluen t Expr essions LanguageVariable (t ype) Descr iption CellIndex (scalar) Cell Inde x CellMachine (scalar) Cell M achine CellMap (scalar) Cell M ap CellMind (scalar) Cell M in d CellMindDirectional (scalar) Cell M in d D irectional CellMindRatio (scalar) Cell M in d R atio CellNormalizedSumFaceArea (scalar) Cell N ormaliz ed Sum F ace Area CellRefineLevel (scalar) Cell R efine L evel CellSquishIndex (scalar) Cell S quish Inde x CellSurfaceArea (scalar) Cell Sur face Area CellTimeScale (scalar) Cell Time Sc ale CellVolume (scalar) Cell Volume CellVolumeChange (scalar) Cell Volume C hange CellVolumeDerivative (scalar) Cell Volume D erivative CellVolumeError (scalar) Cell Volume E rror CellWarpage (scalar) Cell Warpage CellWeight (scalar) Cell Weigh t CellZoneCounter (scalar) Cell Z one C oun ter CellZoneIndex (scalar) Cell Z one Inde x CellZoneType (scalar) Cell Z one Type ChemicalTimeScale (scalar) Chemic al Time Sc ale CompressibilityFactor (scalar) Compr essibilit y Factor ConnectedRegion (scalar) Connec ted R egion ConservedMassFraction (scalar with sp ecies) Conser ved M ass F raction of %s ContactCellMark (scalar) Contact Cell M ark ContactResistivity (scalar) Contact Resistivit y ConvectionTimeStep (scalar) Convection Time S tep CriticalPressure (scalar) Critical Pressur e CriticalSpecificVolume (scalar) Critical Specific Volume CriticalStrainRate (scalar) Critical Strain R ate CriticalTemperature (scalar) Critical Temp erature CurvatureCorrectionFunctionfr (scalar) Curvature Correction F unction fr DESLengthScale (scalar) DES L ength Sc ale DESTKEDissipationMultiplier (scalar) DES TKE D issipa tion M ultiplier DPMAbsorptionCoefficient (scalar) DPM A bsor ption C oefficien t DPMAccretion (scalar) DPM A ccretion DPMAccretionRate (scalar) DPM A ccretion R ate DPMApproachingPackingLimit (scalar) DPM A pproaching P acking Limit 681Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Appendix: Supp orted F ield VariablesVariable (t ype) Descr iption DPMBurnout (scalar) DPM B urnout DPMCollisionRate (scalar) DPM C ollision R ate DPMConcentration (scalar) DPM C oncentration DPMDomainPartition (scalar) DPM D omain P artition DPMEmission (scalar) DPM Emission DPMEnthalpySource (scalar) DPM En thalp y Source DPMEvaporationDevolatilization (scalar) DPM E vaporation/D evolatiliza tion DPMMassSource (scalar) DPM M ass S ource DPMMomentumSource (vector) DPM %s M omen tum S ource DPMNumberDensity (scalar) DPM N umb er D ensit y DPMNumberofParcels (scalar) DPM N umb er of P arcels DPMNumberofParticles (scalar) DPM N umb er of P articles DPMScattering (scalar) DPM Sc attering DPMSensibleEnthalpySource (scalar) DPM S ensible En thalp y Source DPMSource (scalar with sp ecies) DPM %s S ource DPMSpecificTurbulentDissipationSource (scalar) DPM S pecific Turbulen t Dissipa tion Source DPMStepsperCell (scalar) DPM S teps p er C ell DPMTurbulentDissipationSource (scalar) DPM Turbulen t Dissipa tion S ource DPMTurbulentKineticEnergySource (scalar) DPM Turbulen t Kinetic Ener gy Source DPMUUReynoldsStressSource (scalar) DPM UU R eynolds S tress S ource DPMUVReynoldsStressSource (scalar) DPM UV R eynolds S tress S ource DPMUWReynoldsStressSource (scalar) DPM UW R eynolds S tress S ource DPMVVReynoldsStressSource (scalar) DPM VV R eynolds S tress S ource DPMVWReynoldsStressSource (scalar) DPM VW R eynolds S tress S ource DPMVelocityMagnitude (scalar) DPM Velocity Magnitude DPMVolume (scalar) DPM Volume DPMVolumeFraction (scalar) DPM Volume F raction DPMWWReynoldsStressSource (scalar) DPM WW R eynolds S tress S ource DPMWallForce (vector) DPM Wall %s F orce DPMWallNormalPressure (scalar) DPM Wall N ormal P ressur e DQMOM-m4 (scalar) DQMOM-m4 DRGReducedNumberofReactions (scalar) DRG Reduc ed N umb er of R eactions DRGReducedNumberofSpecies (scalar) DRG Reduc ed N umb er of S pecies DamkohlerNumber (scalar) Damk ohler N umb er Density (scalar) Densit y DensityAll (scalar) Densit y All Diameter (scalar) Diamet er Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 682Fluen t Expr essions LanguageVariable (t ype) Descr iption DiffusionTimeStep (scalar) Diffusion Time S tep DiffusivityMeshSmoothing (scalar) Diffusivit y mesh S moothing DropletAverageRadiusmicrons (scalar) Droplet A verage R adius (micr ons) DropletCriticalRadiusmicrons (scalar) Droplet C ritical Radius (micr ons) DropletGrowthRatemicronss (scalar) Droplet G rowth R ate (micr ons/s) DropletSurfaceTension (scalar) Droplet Sur face Tension DynamicAlgebraicVarianceConstant (scalar) Dynamic A lgebr aic Varianc e Constan t DynamicCellVolumeChange (scalar) Dynamic C ell Volume C hange DynamicPressure (scalar) Dynamic P ressur e DynamicPrismFaceCavMarks (scalar) Dynamic P rism F ace Cav. Marks DynamicViscosity (scalar) Molecular Viscosity EDCCellVolumeFraction (scalar) EDC C ell Volume F raction EdgeLengthRatio (scalar) Edge L ength R atio EffDiffCoefof (scalar with sp ecies) Eff Diff C oef of %s EffectivePrandtlNumber (scalar) Effective Prandtl N umb er EffectiveThermalConductivity (scalar) Effective Thermal C onduc tivit y EffectiveViscosity (scalar) Effective Viscosity ElectricCurrentMagnitude (scalar) Electric Current Magnitude ElectricPotential (scalar) Electric Potential ElectricalConductivity (scalar) Electrical C onduc tivit y ElectrodeSurfacePotential (scalar) Electrode Sur face Potential ElementAcousticCourantNumber (scalar) Cell A coustic C ourant Numb er ElementAspectRatio (scalar) Aspect Ratio ElementConvectionCourantNumber (scalar) Cell C onvective Courant Numb er ElementReynoldsNumber (scalar) Cell R eynolds N umb er ElementWallDistance (scalar) Cell Wall D istanc e EllipticRelaxationFunction (scalar) Elliptic R elaxa tion F unction EnthalpyAp (scalar) Enthalp y Ap EnthalpySource (scalar) Enthalp y Source Enthalpyof (scalar with sp ecies) Enthalp y of %s Entropyof (scalar with sp ecies) Entropy of %s EquilibriumMassfractionof (scalar with sp ecies) Equilibr ium M ass fr action of %s EquilibriumTemperature (scalar) Equilibr ium Temp erature EvaporationHeatFlux (scalar) Evaporation H eat Flux ExistingValue (scalar) Existing Value ExpansionRatio (scalar) Expansion R atio ExternalTemperatureShell (scalar) External Temp erature (Shell) 683Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Appendix: Supp orted F ield VariablesVariable (t ype) Descr iption F1DampingFunction (scalar) F-1 D amping F unction F2DampingFunction (scalar) F-2 D amping F unction FaceAreaMagnitude (scalar) Face Area M agnitude FaceHandedness (scalar) Face Handedness FaceRadiation (scalar) Face Radia tion FaceSkew (scalar) Face Skew FaceSquishIndex (scalar) Face Squish Inde x FaceWarpage (scalar) Face Warpage FaradaicCurrentDensity (scalar) Faradaic C urrent Densit y FaradaicHeatSource (scalar) Faradaic H eat Source FaradaicVoltageJump (scalar) Faradaic Voltage J ump FaradaicVoltageResistance (scalar) Faradaic Voltage R esistanc e FilmCourantNumber (scalar) Film C ourant Numb er FilmCoverage (scalar) Film C overage FilmDPMEnergySource (scalar) Film DPM Ener gy Source FilmDPMMassSource (scalar) Film DPM M ass S ource FilmDPMXMomentumSource (scalar) Film DPM X-M omen tum S ource FilmDPMYMomentumSource (scalar) Film DPM Y-M omen tum S ource FilmDPMZMomentumSource (scalar) Film DPM Z-M omen tum S ource FilmDensity (scalar) Film D ensit y FilmEffectivePressure (scalar) Film E ffective Pressur e FilmMass (scalar) Film M ass FilmOutflowMass (scalar) Film Outflo w M ass FilmPassiveScalar (scalar) Film P assiv e Sc alar FilmPhaseChangeRate (scalar) Film P hase C hange R ate FilmSecondaryPhaseCollectionCoef (scalar) Film S econdar y Phase C ollec tion Coef FilmSecondaryPhaseMass (scalar) Film S econdar y Phase M ass FilmSeparatedDiam (scalar) Film S epar ated D iam FilmSeparatedMass (scalar) Film S epar ated M ass FilmSeparationRate (scalar) Film S epar ation R ate FilmStrippedDiam (scalar) Film S tripped D iam FilmStrippedMass (scalar) Film S tripped M ass FilmStrippingRate (scalar) Film S tripping R ate FilmStrippingWeberNumber (scalar) Film S tripping Weber N umb er FilmSurfaceTemperature (scalar) Film Sur face Temp erature FilmSurfaceVelocity (vector) Film Sur face %s-V elocity FilmSurfaceVelocityMagnitude (scalar) Film Sur face Velocity Magnitude Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 684Fluen t Expr essions LanguageVariable (t ype) Descr iption FilmTemperature (scalar) Film Temp erature FilmThickness (scalar) Film Thick ness FilmVelocity (vector) Film %s-V elocity FilmVelocityMagnitude (scalar) Film Velocity Magnitude FilmWeberNumber (scalar) Film Weber N umb er FineScaleMassfractionof (scalar with sp ecies) Fine Sc ale M ass fr action of %s FineScaleTemperature (scalar) Fine Sc ale Temp erature FiniteRateSource (scalar) Finite-Rate Source FlameAreaDensity (scalar) Flame A rea D ensit y FlameAreaDestruction (scalar) Flame A rea D estruction FlameAreaProductionP1 (scalar) Flame A rea P roduc tion P1 FlameAreaProductionP2 (scalar) Flame A rea P roduc tion P2 FlameAreaProductionP3 (scalar) Flame A rea P roduc tion P3 FlameAreaProductionP4 (scalar) Flame A rea P roduc tion P4 FlameletMeanTemperature (scalar) Mean Temp erature Fmean2Ap (scalar) Fmean2 A p Fmean2Source (scalar) Fmean2 S ource FmeanAp (scalar) Fmean A p FmeanSource (scalar) Fmean S ource FmuDampingFunction (scalar) F-mu D amping F unction FrictionalViscosity (scalar) Frictional Viscosity Fvar2Ap (scalar) Fvar2 A p Fvar2Prod (scalar) Fvar2 P rod Fvar2Source (scalar) Fvar2 S ource FvarAp (scalar) Fvar A p FvarProd (scalar) Fvar P rod FvarSource (scalar) Fvar S ource GasConstantR (scalar) Gas C onstan t (R) GeometricRoughnessHeight (scalar) Geometr ic Roughness H eigh t GequationAp (scalar) G-equa tion A p GequationSource (scalar) G-equa tion S ource GradientQualityMeasure (scalar) Gradien t Qualit y Measur e GranularBulkViscosity (scalar) Granular B ulk Viscosity GranularConductivity (scalar) Granular C onduc tivit y GranularPressure (scalar) Granular P ressur e GranularPressureGcmpn (vector) Granular P ressur e G %s cmpn GranularTemperature (scalar) Granular Temp erature GvarianceAp (scalar) G-varianc e Ap 685Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Appendix: Supp orted F ield VariablesVariable (t ype) Descr iption GvarianceSource (scalar) G-varianc e Source HTCCellMark (scalar) HTC Cell M ark HTCLBBoundaryZones (scalar) HTC LB B oundar y Zones HTCLBVolumeFraction (scalar) HTC LB Volume F raction HeatExchangerSource (scalar) Heat Exchanger S ource HeatReleaseRate (scalar) Heat Release R ate HeatTransferCoefficient (scalar) Surface Heat Transf er C oef. HeatofHeterogeneousReaction (scalar) Heat of H eterogeneous R eaction HeatofReaction (scalar) Heat of R eaction Helicity (scalar) Helicit y HreconNorm (scalar) Hrecon N orm HviscNorm (scalar) Hvisc N orm IgnitionVariable (scalar) Ignition Variable IgnitionVariableProduction (scalar) Ignition Variable P roduc tion IncidentRadiation (scalar) Inciden t Radia tion IncidentRadiationInner (scalar) Inciden t Radia tion (Inner) InertDensity (scalar) Iner t Densit y InertEnthalpy (scalar) Iner t En thalp y InertMassFraction (scalar) Iner t Mass F raction InertSpecificHeat (scalar) Iner t Specific H eat InertialConvectiveVariance (scalar) Iner tial-C onvective Varianc e InterfaceOverlapFraction (scalar) Interface Overlap F raction InterfaceWallIDs (scalar) Interface Wall IDs InterfacialAreaConcentration (scalar) Interfacial A rea C oncentration IntermittencyAp (scalar) Intermitt ency Ap IntermittencyEffective (scalar) Intermitt ency Effective IntermittencyEffectiveSmooth (scalar) Intermitt ency Effective Smooth IntermittencySource (scalar) Intermitt ency Source IntermittentTurbNetFlameStretch (scalar) Intermitt ent Turb N et F lame S tretch JetAcousticPower (scalar) Jet A coustic P ower JetAcousticPowerLeveldB (scalar) Jet A coustic P ower L evel (dB) JouleHeatSource (scalar) Joule H eat Source LEESelfNoiseXSource (scalar) LEE S elf-N oise X-S ource LEESelfNoiseYSource (scalar) LEE S elf-N oise Y-Source LEESelfNoiseZSource (scalar) LEE S elf-N oise Z-S ource LEEShearNoiseXSource (scalar) LEE S hear-N oise X-S ource LEEShearNoiseYSource (scalar) LEE S hear-N oise Y-Source LEEShearNoiseZSource (scalar) LEE S hear-N oise Z-S ource Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 686Fluen t Expr essions LanguageVariable (t ype) Descr iption LEETotalNoiseXSource (scalar) LEE Total N oise X-S ource LEETotalNoiseYSource (scalar) LEE Total N oise Y-Source LEETotalNoiseZSource (scalar) LEE Total N oise Z-S ource LESSubgridTurbulentViscosity (scalar) LES Sub grid Turbulen t Viscosity LamDiffCoefof (scalar with sp ecies) Lam D iff C oef of %s Lambda2Criterion (scalar) Lamb da 2 C riterion LaminarFlameSpeed (scalar) Laminar F lame S peed LaminarFlameThickness (scalar) Laminar F lame Thick ness LaminarKineticEnergy (scalar) Laminar K inetic Ener gy LevelsetFunction (scalar) Level-set F unction LilleysSelfNoiseSource (scalar) Lille y's S elf-N oise S ource LilleysShearNoiseSource (scalar) Lille y's S hear-N oise S ource LilleysTotalNoiseSource (scalar) Lille y's Total N oise S ource LiquidDensityLiquidPhase (scalar) Liquid D ensit y (Liquid-P hase) LiquidFraction (scalar) Liquid F raction LiquidMassFraction (scalar) Liquid M ass F raction LiquidMassGenerationRate (scalar) Liquid M ass G ener ation R ate LiquidPhaseHeatFlux (scalar) Liquid P hase H eat Flux LiquidSpeciesMassFraction (scalar with sp ecies) Liquid sp ecies mass fr action of %s LiquidusTemperature (scalar) Liquidus Temp erature LocalIgnitionTime (scalar) Local Ignition Time Log10DropletsNucleationRate (scalar) Log10(D roplets N uclea tion R ate) Log10DropletsPerUnitVolume (scalar) Log10(D roplets P er U nit Volume) LumpID (scalar) Lump ID MPPSource (scalar) MP P S ource MachNumber (scalar) Mach N umb er MagnitudeofSensitivitytoBodyForces (scalar) Magnitude of S ensitivit y to Body Forces MagnitudeofSensitivitytoBodyForcesCellValues (scalar)Magnitude of S ensitivit y to Body Forces (C ell Values) MarkPoorElements (scalar) Mark Poor E lemen ts MassFraction (scalar with sp ecies) Mass fr action of %s MassImbalance (scalar) Mass Imbalanc e MaxPackingLimit (scalar) Max. Packing Limit MeanDeformation (scalar) Mean D eformation MeanDistancefromFlame (scalar) Mean D istanc e from F lame MeanGranularTemperature (scalar) Mean G ranular Temp erature MeanMassFractionof (scalar with sp ecies) Mean M ass F raction of %s MeanMassfraction (scalar with sp ecies) Mean %s M ass fr action 687Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Appendix: Supp orted F ield VariablesVariable (t ype) Descr iption MeanMixtureFraction (scalar) Mean M ixture Fraction MeanPhaseDiameter (scalar) Mean P hase D iamet er MeanPressureCoefficient (scalar) Mean P ressur e Coefficien t MeanReactionProgress (scalar) Mean R eaction P rogress MeanSkinFrictionCoefficient (scalar) Mean S kin Friction C oefficien t MeanSoundPressure (scalar) Mean S ound P ressur e MeanSoundWaveEqModelSource (scalar) Mean S ound WaveEq M odel S ource MeanStaticPressure (scalar) Mean S tatic P ressur e MeanStaticTemperature (scalar) Mean S tatic Temp erature MeanSurfaceHeatFlux (scalar) Mean Sur face Heat Flux MeanSurfaceHeatTransferCoef (scalar) Mean Sur face Heat Transf er C oef. MeanSurfaceNusseltNumber (scalar) Mean Sur face Nusselt N umb er MeanSurfaceStantonNumber (scalar) Mean Sur face Stanton N umb er MeanVelocityMagnitude (scalar) Mean Velocity Magnitude MeanVolumefraction (scalar) Mean Volume fr action MeanofMixtureFraction (scalar) Mean of M ixture Fraction MeshVariationEffect (scalar) Mesh Variation E ffect MeshVelocity (vector) Mesh %s-V elocity MigrationDiffCoefof (scalar with sp ecies) Migration D iff C oef of %s MixtureDensity (scalar) Mixture Densit y MixtureFractionVariance (scalar) Mixture Fraction Varianc e ModifiedTurbViscosityAp (scalar) Modified Turb Viscosity Ap ModifiedTurbViscositySource (scalar) Modified Turb Viscosity Source ModifiedTurbulenceViscosity (scalar) Modified Turbulen t Viscosity MolarConcentration (scalar with sp ecies) Molar C oncentration of %s MoleFraction (scalar with sp ecies) Mole fr action of %s MolecularMass (scalar) Mean M olecular Weigh t MomThicknReAp (scalar) Mom. Thick n. Re Ap MomThicknReSource (scalar) Mom. Thick n. Re Source MomentumThicknessRe (scalar) Momen tum Thick ness R e NetFlameAreaProduction (scalar) Net F lame A rea P roduc tion NetReactionRateof (scalar with sp ecies) Net R eaction R ate of %s NodePairCheck (scalar) Node P air C heck NonEquilibriumThermalModelSource (scalar) Non-E quilibr ium Thermal M odel Source Normalizedvolumefraction (scalar) Normaliz ed v olume fr action NormalOptimalDisplacement (scalar) Normal Optimal D isplac emen t NormalShapeSensitivity (scalar) Normal S hap e Sensitivit y Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 688Fluen t Expr essions LanguageVariable (t ype) Descr iption NormalizedQCriterion (scalar) Normaliz ed Q C riterion OrthogonalQuality (scalar) Orthogonal Q ualit y OversetCellType (scalar) Overset C ell Type OversetDonorCount (scalar) Overset D onor C oun t OversetReceptorCount (scalar) Overset R eceptor C oun t PDFDepartureEnthalpy (scalar) PDF D epar ture En thalp y PDFLaminarFlameSpeed (scalar) Laminar F lame S peed PDFMeanTemperature (scalar) Mean S tatic Temp erature PDFStaticTemperature (scalar) Static Temp erature PDFTableAdiabaticEnthalpy (scalar) PDF Table A diaba tic En thalp y PDFTableHeatLossGain (scalar) PDF Table H eat Loss/G ain PHI (scalar) PHI ParticleTimeStep (scalar) Particle Time S tep PartitionNeighbors (scalar) Partition N eighb ors PdfEnthalpy (scalar) Pdf En thalp y PdfFmean (scalar) Pdf Fmean PdfFvar (scalar) Pdf Fv ar PhaseID (scalar) Phase ID PollutantCorrectionAp (scalar) Pollutan t Correction A p PollutantCorrectionSource (scalar) Pollutan t Correction S ource Position (vector) %s-C oordina te PrandtlNumber (scalar) Molecular P randtl N umb er PreconditioningReferenceVelocity (scalar) Preconditioning R eference Velocity PressureCoefficient (scalar) Pressur e Coefficien t PressureCorrectionAp (scalar) Pressur e Correction A p PressureCorrectionSource (scalar) Pressur e Correction S ource PressureSpectrumIm0 (scalar) Pressur e Spectrum Im 0 PressureSpectrumIm1 (scalar) Pressur e Spectrum Im 1 PressureSpectrumIm10 (scalar) Pressur e Spectrum Im 10 PressureSpectrumIm11 (scalar) Pressur e Spectrum Im 11 PressureSpectrumIm12 (scalar) Pressur e Spectrum Im 12 PressureSpectrumIm13 (scalar) Pressur e Spectrum Im 13 PressureSpectrumIm14 (scalar) Pressur e Spectrum Im 14 PressureSpectrumIm15 (scalar) Pressur e Spectrum Im 15 PressureSpectrumIm16 (scalar) Pressur e Spectrum Im 16 PressureSpectrumIm17 (scalar) Pressur e Spectrum Im 17 PressureSpectrumIm18 (scalar) Pressur e Spectrum Im 18 PressureSpectrumIm19 (scalar) Pressur e Spectrum Im 19 689Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Appendix: Supp orted F ield VariablesVariable (t ype) Descr iption PressureSpectrumIm2 (scalar) Pressur e Spectrum Im 2 PressureSpectrumIm3 (scalar) Pressur e Spectrum Im 3 PressureSpectrumIm4 (scalar) Pressur e Spectrum Im 4 PressureSpectrumIm5 (scalar) Pressur e Spectrum Im 5 PressureSpectrumIm6 (scalar) Pressur e Spectrum Im 6 PressureSpectrumIm7 (scalar) Pressur e Spectrum Im 7 PressureSpectrumIm8 (scalar) Pressur e Spectrum Im 8 PressureSpectrumIm9 (scalar) Pressur e Spectrum Im 9 PressureSpectrumRe0 (scalar) Pressur e Spectrum R e 0 PressureSpectrumRe1 (scalar) Pressur e Spectrum R e 1 PressureSpectrumRe10 (scalar) Pressur e Spectrum R e 10 PressureSpectrumRe11 (scalar) Pressur e Spectrum R e 11 PressureSpectrumRe12 (scalar) Pressur e Spectrum R e 12 PressureSpectrumRe13 (scalar) Pressur e Spectrum R e 13 PressureSpectrumRe14 (scalar) Pressur e Spectrum R e 14 PressureSpectrumRe15 (scalar) Pressur e Spectrum R e 15 PressureSpectrumRe16 (scalar) Pressur e Spectrum R e 16 PressureSpectrumRe17 (scalar) Pressur e Spectrum R e 17 PressureSpectrumRe18 (scalar) Pressur e Spectrum R e 18 PressureSpectrumRe19 (scalar) Pressur e Spectrum R e 19 PressureSpectrumRe2 (scalar) Pressur e Spectrum R e 2 PressureSpectrumRe3 (scalar) Pressur e Spectrum R e 3 PressureSpectrumRe4 (scalar) Pressur e Spectrum R e 4 PressureSpectrumRe5 (scalar) Pressur e Spectrum R e 5 PressureSpectrumRe6 (scalar) Pressur e Spectrum R e 6 PressureSpectrumRe7 (scalar) Pressur e Spectrum R e 7 PressureSpectrumRe8 (scalar) Pressur e Spectrum R e 8 PressureSpectrumRe9 (scalar) Pressur e Spectrum R e 9 ProductFormationRate (scalar) Produc t Formation R ate ProductionofEntropy (scalar) Produc tion of En tropy Productionofk (scalar) Produc tion of k Productionoflaminark (scalar) Produc tion of laminar k ProgressVariable (scalar) Progress Variable ProgressVariableAp (scalar) Progress Variable A p ProgressVariableGradientMagnitude (scalar) Progress Variable G radien t Magnitude ProgressVariableSource (scalar) Progress Variable S ource ProgressVariableVariance (scalar) Progress Variable Varianc e Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 690Fluen t Expr essions LanguageVariable (t ype) Descr iption Q (scalar) Q QCriterion (scalar) Q Criterion QTimeAverage (scalar) Q Time-A verage QuenchingHeatFlux (scalar) Quenching H eat Flux RMSEGranularTemperature (scalar) RMSE G ranular Temp erature RMSEMassFractionof (scalar with sp ecies) RMSE M ass F raction of %s RMSEPhaseDiameter (scalar) RMSE P hase D iamet er RMSEReactionProgress (scalar) RMSE R eaction P rogress RMSESoundPressure (scalar) RMSE S ound P ressur e RMSESoundWaveEqModelSource (scalar) RMSE S ound WaveEq M odel S ource RMSEStaticPressure (scalar) RMSE S tatic P ressur e RMSEStaticTemperature (scalar) RMSE S tatic Temp erature RMSEVelocityMagnitude (scalar) RMSE Velocity Magnitude RMSEVolumefraction (scalar) RMSE Volume fr action RMSEofMixtureFraction (scalar) RMSE of M ixture Fraction RMSMassfraction (scalar with sp ecies) RMS %s M ass fr action RMSStaticTemperature (scalar) RMS S tatic Temp erature RMSTemperature (scalar) RMS Temp erature RadialVelocity (scalar) Radial Velocity RadiationIntensityNormalizedStdDeviation (scalar)Radia tion In tensit y.Normaliz ed S td Deviation RadiationTemperature (scalar) Radia tion Temp erature RadiativeHeatFlux (scalar) Radia tion H eat Flux ReactorNetTemperature (scalar) Reactor N et Temp erature ReactorNetZoneID (scalar) Reactor N et Z one ID ReconstructiondHd (vector) Reconstr uction dH/d%s ReconstructiondTd (vector) Reconstr uction dT/d%s ReconstructiondXVelocityd (vector) Reconstr uction dX-V elocity/d%s ReconstructiondYVelocityd (vector) Reconstr uction dY-V elocity/d%s ReconstructiondZVelocityd (vector) Reconstr uction dZ-V elocity/d%s Reconstructionded (vector) Reconstr uction de/d%s Reconstructiondkd (vector) Reconstr uction dk/d%s Reconstructiondnutd (vector) Reconstr uction dnut/d%s Reconstructiondpd (vector) Reconstr uction dp/d%s Reconstructiondrhod (vector) Reconstr uction dr ho/d%s Reconstructiondvofd (vector) Reconstr uction d vof/d%s ReducedPressure (scalar) Reduc ed P ressur e ReducedTemperature (scalar) Reduc ed Temp erature 691Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Appendix: Supp orted F ield VariablesVariable (t ype) Descr iption ReflectedIRSolarFlux (scalar) Reflec ted IR S olar F lux ReflectedRadiationFlux (scalar) Reflec ted R adia tion F lux ReflectedVisibleSolarFlux (scalar) Reflec ted Visible S olar F lux RefractiveIndex (scalar) Refractive Inde x RelativeHumidity (scalar) Relative Humidit y RelativeStrain (scalar) Relative Strain RichFlammabilityFactor (scalar) Rich F lammabilit y Factor RngStrainrateTerm (scalar) Rng S trainr ate Term SASTermStrainRateMagnitude (scalar) SAS Term S train R ate M agnitude SPLfor13OctaveBandat05HzdB (scalar) SPL f or 1/3-O ctave Band a t 0.5Hz (dB) SPLfor13OctaveBandat063HzdB (scalar) SPL f or 1/3-O ctave Band a t 0.63Hz (dB) SPLfor13OctaveBandat08HzdB (scalar) SPL f or 1/3-O ctave Band a t 0.8Hz (dB) SPLfor13OctaveBandat100HzdB (scalar) SPL f or 1/3-O ctave Band a t 100Hz (dB) SPLfor13OctaveBandat100kHzdB (scalar) SPL f or 1/3-O ctave Band a t 100kHz (dB) SPLfor13OctaveBandat10HzdB (scalar) SPL f or 1/3-O ctave Band a t 10Hz (dB) SPLfor13OctaveBandat10kHzdB (scalar) SPL f or 1/3-O ctave Band a t 10kHz (dB) SPLfor13OctaveBandat125HzdB (scalar) SPL f or 1/3-O ctave Band a t 1.25Hz (dB) SPLfor13OctaveBandat125kHzdB (scalar) SPL f or 1/3-O ctave Band a t 1.25kHz (dB) SPLfor13OctaveBandat160HzdB (scalar) SPL f or 1/3-O ctave Band a t 160Hz (dB) SPLfor13OctaveBandat16HzdB (scalar) SPL f or 1/3-O ctave Band a t 1.6Hz (dB) SPLfor13OctaveBandat16kHzdB (scalar) SPL f or 1/3-O ctave Band a t 1.6kHz (dB) SPLfor13OctaveBandat1HzdB (scalar) SPL f or 1/3-O ctave Band a t 1Hz (dB) SPLfor13OctaveBandat1kHzdB (scalar) SPL f or 1/3-O ctave Band a t 1kHz (dB) SPLfor13OctaveBandat200HzdB (scalar) SPL f or 1/3-O ctave Band a t 200Hz (dB) SPLfor13OctaveBandat20HzdB (scalar) SPL f or 1/3-O ctave Band a t 20Hz (dB) SPLfor13OctaveBandat20kHzdB (scalar) SPL f or 1/3-O ctave Band a t 20kHz (dB) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 692Fluen t Expr essions LanguageVariable (t ype) Descr iption SPLfor13OctaveBandat250HzdB (scalar) SPL f or 1/3-O ctave Band a t 250Hz (dB) SPLfor13OctaveBandat25HzdB (scalar) SPL f or 1/3-O ctave Band a t 2.5Hz (dB) SPLfor13OctaveBandat25kHzdB (scalar) SPL f or 1/3-O ctave Band a t 2.5kHz (dB) SPLfor13OctaveBandat2HzdB (scalar) SPL f or 1/3-O ctave Band a t 2Hz (dB) SPLfor13OctaveBandat2kHzdB (scalar) SPL f or 1/3-O ctave Band a t 2kHz (dB) SPLfor13OctaveBandat315HzdB (scalar) SPL f or 1/3-O ctave Band a t 3.15Hz (dB) SPLfor13OctaveBandat315kHzdB (scalar) SPL f or 1/3-O ctave Band a t 3.15kHz (dB) SPLfor13OctaveBandat400HzdB (scalar) SPL f or 1/3-O ctave Band a t 400Hz (dB) SPLfor13OctaveBandat40HzdB (scalar) SPL f or 1/3-O ctave Band a t 40Hz (dB) SPLfor13OctaveBandat40kHzdB (scalar) SPL f or 1/3-O ctave Band a t 40kHz (dB) SPLfor13OctaveBandat4HzdB (scalar) SPL f or 1/3-O ctave Band a t 4Hz (dB) SPLfor13OctaveBandat4kHzdB (scalar) SPL f or 1/3-O ctave Band a t 4kHz (dB) SPLfor13OctaveBandat500HzdB (scalar) SPL f or 1/3-O ctave Band a t 500Hz (dB) SPLfor13OctaveBandat50HzdB (scalar) SPL f or 1/3-O ctave Band a t 50Hz (dB) SPLfor13OctaveBandat50kHzdB (scalar) SPL f or 1/3-O ctave Band a t 50kHz (dB) SPLfor13OctaveBandat5HzdB (scalar) SPL f or 1/3-O ctave Band a t 5Hz (dB) SPLfor13OctaveBandat5kHzdB (scalar) SPL f or 1/3-O ctave Band a t 5kHz (dB) SPLfor13OctaveBandat630HzdB (scalar) SPL f or 1/3-O ctave Band a t 630Hz (dB) SPLfor13OctaveBandat63HzdB (scalar) SPL f or 1/3-O ctave Band a t 6.3Hz (dB) SPLfor13OctaveBandat63kHzdB (scalar) SPL f or 1/3-O ctave Band a t 6.3kHz (dB) SPLfor13OctaveBandat800HzdB (scalar) SPL f or 1/3-O ctave Band a t 800Hz (dB) SPLfor13OctaveBandat80HzdB (scalar) SPL f or 1/3-O ctave Band a t 80Hz (dB) SPLfor13OctaveBandat80kHzdB (scalar) SPL f or 1/3-O ctave Band a t 80kHz (dB) 693Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Appendix: Supp orted F ield VariablesVariable (t ype) Descr iption SPLfor13OctaveBandat8HzdB (scalar) SPL f or 1/3-O ctave Band a t 8Hz (dB) SPLfor13OctaveBandat8kHzdB (scalar) SPL f or 1/3-O ctave Band a t 8kHz (dB) SPLforConstWidthBand0dB (scalar) SPL f or C onst Width B and 0 (dB) SPLforConstWidthBand10dB (scalar) SPL f or C onst Width B and 10 (dB) SPLforConstWidthBand11dB (scalar) SPL f or C onst Width B and 11 (dB) SPLforConstWidthBand12dB (scalar) SPL f or C onst Width B and 12 (dB) SPLforConstWidthBand13dB (scalar) SPL f or C onst Width B and 13 (dB) SPLforConstWidthBand14dB (scalar) SPL f or C onst Width B and 14 (dB) SPLforConstWidthBand15dB (scalar) SPL f or C onst Width B and 15 (dB) SPLforConstWidthBand16dB (scalar) SPL f or C onst Width B and 16 (dB) SPLforConstWidthBand17dB (scalar) SPL f or C onst Width B and 17 (dB) SPLforConstWidthBand18dB (scalar) SPL f or C onst Width B and 18 (dB) SPLforConstWidthBand19dB (scalar) SPL f or C onst Width B and 19 (dB) SPLforConstWidthBand1dB (scalar) SPL f or C onst Width B and 1 (dB) SPLforConstWidthBand2dB (scalar) SPL f or C onst Width B and 2 (dB) SPLforConstWidthBand3dB (scalar) SPL f or C onst Width B and 3 (dB) SPLforConstWidthBand4dB (scalar) SPL f or C onst Width B and 4 (dB) SPLforConstWidthBand5dB (scalar) SPL f or C onst Width B and 5 (dB) SPLforConstWidthBand6dB (scalar) SPL f or C onst Width B and 6 (dB) SPLforConstWidthBand7dB (scalar) SPL f or C onst Width B and 7 (dB) SPLforConstWidthBand8dB (scalar) SPL f or C onst Width B and 8 (dB) SPLforConstWidthBand9dB (scalar) SPL f or C onst Width B and 9 (dB) SPLforOctaveBandat125HzdB (scalar) SPL f or O ctave Band a t 125Hz (dB) SPLforOctaveBandat16HzdB (scalar) SPL f or O ctave Band a t 16Hz (dB) SPLforOctaveBandat16kHzdB (scalar) SPL f or O ctave Band a t 16kHz (dB) SPLforOctaveBandat1HzdB (scalar) SPL f or O ctave Band a t 1Hz (dB) SPLforOctaveBandat1kHzdB (scalar) SPL f or O ctave Band a t 1kHz (dB) SPLforOctaveBandat250HzdB (scalar) SPL f or O ctave Band a t 250Hz (dB) SPLforOctaveBandat2HzdB (scalar) SPL f or O ctave Band a t 2Hz (dB) SPLforOctaveBandat2kHzdB (scalar) SPL f or O ctave Band a t 2kHz (dB) SPLforOctaveBandat315HzdB (scalar) SPL f or O ctave Band a t 31.5Hz (dB) SPLforOctaveBandat315kHzdB (scalar) SPL f or O ctave Band a t 31.5kHz (dB) SPLforOctaveBandat4HzdB (scalar) SPL f or O ctave Band a t 4Hz (dB) SPLforOctaveBandat4kHzdB (scalar) SPL f or O ctave Band a t 4kHz (dB) SPLforOctaveBandat500HzdB (scalar) SPL f or O ctave Band a t 500Hz (dB) SPLforOctaveBandat63HzdB (scalar) SPL f or O ctave Band a t 63Hz (dB) SPLforOctaveBandat63kHzdB (scalar) SPL f or O ctave Band a t 63kHz (dB) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 694Fluen t Expr essions LanguageVariable (t ype) Descr iption SPLforOctaveBandat8HzdB (scalar) SPL f or O ctave Band a t 8Hz (dB) SPLforOctaveBandat8kHzdB (scalar) SPL f or O ctave Band a t 8kHz (dB) SPLforOneThirdOctaveBandat125HzdB (scalar) SPL f or 1/3-O ctave Band a t 125Hz (dB) SPLforOneThirdOctaveBandat125kHzdB (scalar) SPL f or 1/3-O ctave Band a t 12.5kHz (dB) SPLforOneThirdOctaveBandat12p5HzdB (scalar) SPL f or 1/3-O ctave Band a t 12.5Hz (dB) SPLforOneThirdOctaveBandat16HzdB (scalar) SPL f or 1/3-O ctave Band a t 16Hz (dB) SPLforOneThirdOctaveBandat16kHzdB (scalar) SPL f or 1/3-O ctave Band a t 16kHz (dB) SPLforOneThirdOctaveBandat25HzdB (scalar) SPL f or 1/3-O ctave Band a t 25Hz (dB) SPLforOneThirdOctaveBandat25kHzdB (scalar) SPL f or 1/3-O ctave Band a t 25kHz (dB) SPLforOneThirdOctaveBandat315HzdB (scalar) SPL f or 1/3-O ctave Band a t 315Hz (dB) SPLforOneThirdOctaveBandat315kHzdB (scalar) SPL f or 1/3-O ctave Band a t 31.5kHz (dB) SPLforOneThirdOctaveBandat31p5HzdB (scalar) SPL f or 1/3-O ctave Band a t 31.5Hz (dB) SPLforOneThirdOctaveBandat63HzdB (scalar) SPL f or 1/3-O ctave Band a t 63Hz (dB) SPLforOneThirdOctaveBandat63kHzdB (scalar) SPL f or 1/3-O ctave Band a t 63kHz (dB) SSTF1BlendingFunction (scalar) SST F1 B lending F unction SSTF2BlendingFunction (scalar) SST F2 B lending F unction SaturationPressure (scalar) Saturation P ressur e SaturationRatio (scalar) Saturation R atio SaturationTemperature (scalar) Saturation Temp erature ScalarDissipation (scalar) Scalar D issipa tion ScatteringCoefficient (scalar) Scattering C oefficien t SchmidtNumber (scalar) Schmidt N umb er SecondaryMeanMixtureFraction (scalar) Secondar y Mean M ixture Fraction SecondaryMixtureFractionVariance (scalar) Secondar y M ixture Fraction Varianc e SensibleEnthalpy (scalar) Sensible En thalp y SensitivityToViscosity (scalar) Sensitivit y To Viscosity SensitivitytoBodyForceXComponent (scalar) Sensitivit y to Body Force X-Comp onen t SensitivitytoBodyForceXComponentCellValues (scalar)Sensitivit y to Body Force X-Comp onen t (Cell Values) 695Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Appendix: Supp orted F ield VariablesVariable (t ype) Descr iption SensitivitytoBodyForceYComponent (scalar) Sensitivit y to Body Force Y-Comp onen t SensitivitytoBodyForceYComponentCellValues (scalar)Sensitivit y to Body Force Y-Comp onen t (Cell Values) SensitivitytoBodyForceZComponent (scalar) Sensitivit y to Body Force Z-Comp onen t SensitivitytoBodyForceZComponentCellValues (scalar)Sensitivit y to Body Force Z-Comp onen t (Cell Values) SensitivitytoBoundaryHeatFlux (scalar) Sensitivit y to Boundar y Heat Flux SensitivitytoBoundaryPressure (scalar) Sensitivit y to Boundar y Pressur e SensitivitytoBoundaryTemperature (scalar) Sensitivit y to Boundar y Temp erature SensitivitytoBoundaryVelocity (vector) Sensitivit y to Boundar y %s-V elocity SensitivitytoEnergySources (scalar) Sensitivit y to Ener gy Sources SensitivitytoEnergySourcesCellValues (scalar) Sensitivit y to Ener gy Sources (C ell Values) SensitivitytoFlowBlockage (scalar) Sensitivit y to Flow Blockage SensitivitytoMassSources (scalar) Sensitivit y to M ass S ources SensitivitytoMassSourcesCellValues (scalar) Sensitivit y to M ass S ources (C ell Values) ShapeSensitivityComponent (vector) Shap e Sensitivit y %s C omp onen t ShapeSensitivityMagnitude (scalar) Shap e Sensitivit y Magnitude ShieldingFunctionforSBESorSDES (scalar) Shielding F unction f or SBES or SDES SkewSizeCavMarkType (scalar) Skew/S ize Cav. Mark Type SkewSizeCavMarking (scalar) Skew/S ize Cav. Marking SkewSizeCavSeeds (scalar) Skew/S ize Cav. Seeds SkinFrictionCoefficient (scalar) Skin Friction C oefficien t SmoothedCurvature (scalar) Smoothed C urvature SmoothedVOF (scalar) Smoothed VOF SmoothedVOFGradientMagnitude (scalar) Smoothed VOF G radien t Magnitude SmoothedVOFGradientd (vector) Smoothed VOF G radien t-d%s SolarBINID (scalar) Solar BIN ID SolarHeatFlux (scalar) Solar H eat Flux SolidusTemperature (scalar) Solidus Temp erature SolvedTurbulentKineticEnergyk (scalar) Solved Turbulen t Kinetic Ener gy (k) SoundPotential (scalar) Sound P otential SoundPressure (scalar) Sound P ressur e SoundSpongeLayerMarker (scalar) Sound S ponge La yer M arker SoundWaveEqAp (scalar) Sound WaveEq Ap SoundWaveEqModelSource (scalar) Sound WaveEq M odel S ource SoundWaveEqModelSourceMask (scalar) Sound WaveEq M odel S ource M ask Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 696Fluen t Expr essions LanguageVariable (t ype) Descr iption SoundWaveEqModelSourceSmoothed (scalar) Sound WaveEq M odel S ource Smoothed SoundWaveEqReconstructiondVard (vector) Sound WaveEq Reconstr uction dVar/d%s SoundWaveEqSource (scalar) Sound WaveEq Source SoundWaveEqdVard (vector) Sound WaveEq dV ar/d%s Soundd2Pdt2 (scalar) Sound d2P/dt2 SounddPdt (scalar) Sound dP/dt SourceTerm (scalar with sp ecies) %s S ource Term SourcesofDQMOMm4 (scalar) Sources of DQMOM-m4 SourcesofDQMOMvof (scalar) Sources of DQMOM-v of SparkDiffusionMultiplier (scalar) Spark Diffusion M ultiplier SparkHeatSource (scalar) Spark Heat Source SpatialSpectralBandwidth (scalar) Spatial S pectral Band width SpecDissAp (scalar) Spec D iss A p SpecDissSource (scalar) Spec D iss S ource SpeciesTurbulentTimeScale (scalar) Turbulen t Time Sc ale SpecificDissipationRateOmega (scalar) Specific D issipa tion R ate (Omega) SpecificEnthalpy (scalar) Enthalp y SpecificEntropy (scalar) Entropy SpecificHeatCapacity (scalar) Specific H eat (Cp) SpecificHeatRatiogamma (scalar) Specific H eat Ratio (gamma) SpecificHeatof (scalar with sp ecies) Specific H eat of %s SpecificInternalEnergy (scalar) Internal Ener gy SpecificTotalEnergy (scalar) Total Ener gy SpecificTotalEnthalpy (scalar) Total En thalp y SpeedOfSound (scalar) Sound S peed SpinodalTemperature (scalar) Spino dal Temp erature StaticPressure (scalar) Static P ressur e StaticTemperature (scalar) Static Temp erature SteamDensityGasPhase (scalar) Steam D ensit y (G as-P hase) StoredElementPartition (scalar) Stored C ell P artition StrainRate (scalar) Strain R ate StretchFactor (scalar) Stretch F actor SubcooledVaporTemperature (scalar) Sub cooled Vapor Temp erature SubcriticalCondition (scalar) Sub critical C ondition SubgridDissipationRate (scalar) Sub grid D issipa tion R ate SubgridDynamicPrandtlNumber (scalar) Sub grid D ynamic P randtl N umb er SubgridDynamicScof (scalar with sp ecies) Sub grid D ynamic Sc of %s 697Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Appendix: Supp orted F ield VariablesVariable (t ype) Descr iption SubgridDynamicScofFmean (scalar) Sub grid D ynamic Sc of Fmean SubgridDynamicScofProgressVariable (scalar) Sub grid D ynamic Sc of P rogress Variable SubgridDynamicViscosityConst (scalar) Sub grid D ynamic Viscosity Const SubgridEffectiveViscosity (scalar) Sub grid E ffective Viscosity SubgridFilterLength (scalar) Sub grid Filter L ength SubgridKineticEnergy (scalar) Sub grid K inetic Ener gy SubgridTestFilterLength (scalar) Sub grid Test-F ilter L ength SubgridTurbulentViscosity (scalar) Sub grid Turbulen t Viscosity SubgridTurbulentViscosityRatio (scalar) Sub grid Turbulen t Viscosity Ratio SubtestKineticEnergy (scalar) Subt est K inetic Ener gy SurfaceAcousticPower (scalar) Surface Acoustic P ower SurfaceAcousticPowerLeveldB (scalar) Surface Acoustic P ower L evel (dB) SurfaceClusterID (scalar) Surface Cluster ID SurfaceHeatFlux (scalar) Total Sur face Heat Flux SurfaceHeatTransferCoefficient (scalar) Wall F unc. Heat Tran. Coef. SurfaceIncidentRadiation (scalar) Surface Inciden t Radia tion SurfaceNusseltNumber (scalar) Surface Nusselt N umb er SurfaceStantonNumber (scalar) Surface Stanton N umb er SurfacedpdtRMS (scalar) Surface dp dt RMS TFMEfficiencyFactor (scalar) TFM E fficienc y Factor TFMOmega (scalar) TFM Omega TFMThickeningFactor (scalar) TFM Thick ening F actor TangentialVelocity (scalar) Tangen tial Velocity TemperatureAp (scalar) Temp erature Ap TemperatureEMSurfaceSource (scalar) Temp erature EM Sur face Source TemperatureEMVolumeSource (scalar) Temp erature EM Volume S ource TemperatureSource (scalar) Temp erature Source TemporalSpectralBandwidth (scalar) Temp oral Spectral Band width ThermalConductivity (scalar) Thermal C onduc tivit y ThermalDiffCoefof (scalar with sp ecies) Thermal D iff C oef of %s ThinFilmHeatFlux (scalar) Thin F ilm H eat Flux TimeStep (scalar) Time S tep TimeStepScale (scalar) Time S tep Sc ale TotalEChemHeatSource (scalar) Total EC hem H eat Source TotalEnthalpyDeviation (scalar) Total En thalp y Deviation TotalFluctuationEnergy (scalar) Total F luctuation Ener gy TotalPressure (scalar) Total P ressur e Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 698Fluen t Expr essions LanguageVariable (t ype) Descr iption TotalSurfaceCorrosionRate (scalar) Total Sur face Corrosion R ate TotalTemperature (scalar) Total Temp erature TransmittedIRSolarFlux (scalar) Transmitt ed IR S olar F lux TransmittedRadiationFlux (scalar) Transmitt ed R adia tion F lux TransmittedVisibleSolarFlux (scalar) Transmitt ed Visible S olar F lux TurbDissAp (scalar) Turb D iss A p TurbDissSource (scalar) Turb D iss S ource TurbKinEnergyAp (scalar) Turb K in. Ener gy Ap TurbKinEnergySource (scalar) Turb K in. Ener gy Source TurbulenceDissipationRate (scalar) Turbulen t Dissipa tion R ate (Epsilon) TurbulenceIntensity (scalar) Turbulen t Intensit y TurbulenceIntermittency (scalar) Intermitt ency TurbulenceViscosity (scalar) Turbulen t Viscosity TurbulenceViscosityRatio (scalar) Turbulen t Viscosity Ratio TurbulentFlameSpeed (scalar) Turbulen t Flame S peed TurbulentFlameSpeedSource (scalar) Turbulen t Flame S peed S ource TurbulentKineticEnergyk (scalar) Turbulen t Kinetic Ener gy (k) TurbulentLengthScale (scalar) Turbulen t Length Sc ale TurbulentReynoldsNumberRe_t (scalar) Turbulen t Reynolds N umb er (R e_t) TurbulentReynoldsNumberRe_y (scalar) Turbulen t Reynolds N umb er (R e_y) TurbulentTimeScale (scalar) Turbulen t Time Sc ale TurbulentTimeStep (scalar) Turbulen t Time S tep TurbulentVelocityScale (scalar) Turbulen t Velocity Sc ale TurbulentViscositylargescale (scalar) Turbulen t Viscosity (lar ge-sc ale) TurbulentViscositysmallscale (scalar) Turbulen t Viscosity (small-sc ale) TwoLayerBlendingFunction (scalar) Two La yer B lending F unction UCorrectionVelocity (scalar) U Correction Velocity UnNormalizedProgressVariable (scalar) Un-Normaliz ed P rogress Variable UnNormalizedProgressVariableVariance (scalar) Un-Normaliz ed P rogress Variable Varianc e UnburntDensity (scalar) Unbur nt Densit y UnburntFuelMassFraction (scalar) Unbur nt Fuel M ass F raction UnburntThermalDiffusivity (scalar) Unbur nt Thermal D iffusivit y UserEnergySource (scalar) User Ener gy Source UserMassSource (scalar) User M ass S ource V2FTimeScale (scalar) V2F Time Sc ale VCorrectionVelocity (scalar) V Correction Velocity VOFAp (scalar) VOF A p 699Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Appendix: Supp orted F ield VariablesVariable (t ype) Descr iption VOFGradientd (vector) VOF G radien t-d%s VOFS (scalar) VOF S VaporPhaseHeatFlux (scalar) Vapor P hase H eat Flux VarianceofDistancefromFlame (scalar) Varianc e of D istanc e from F lame VelocityAngle (scalar) Velocity Angle VelocityDivergence (scalar) Velocity Divergenc e VelocityMagnitude (scalar) Velocity Magnitude VelocityVarianceScalev2 (scalar) Velocity Varianc e Sc ale (v2) ViscousConvectiveVariance (scalar) Viscous-C onvective Varianc e ViscousDiffusiveVariance (scalar) Viscous-D iffusiv e Varianc e VolumeGlobFactor (scalar) Volume G lob F actor VolumeGlobSource (scalar) Volume G lob S ource Volumefraction (scalar) Volume fr action VolumetricAbsorbedRadiation (scalar) Volumetr ic A bsorb ed R adia tion VolumetricEmittedRadiation (scalar) Volumetr ic Emitt ed R adia tion Vorticity (vector) %s-V orticit y VorticityMagnitude (scalar) Vorticit y Magnitude WCorrectionVelocity (scalar) W C orrection Velocity WallAdjacentHeatTransferCoef (scalar) Wall A djac ent Heat Transf er C oef. WallAdjacentTemperature (scalar) Wall A djac ent Temp erature WallCoverage (scalar) Wall C overage WallFilmFacePressGradient (vector) Wall F ilm F ace Press %s-G radien t WallFilmFacePressure (scalar) Wall F ilm F ace Pressur e WallFilmHeatFlux (scalar) Wall F ilm H eat Flux WallFilmHeight (scalar) Wall F ilm H eigh t WallFilmImpingementMassFlux (scalar) Wall F ilm Impingemen t Mass F lux WallFilmImpingementMomentum (vector) Wall F ilm Impingemen t %s-M omen tum WallFilmImpingementMomentumMag (scalar) Wall F ilm Impingemen t Momen tum Mag WallFilmMass (scalar) Wall F ilm M ass WallFilmMassM0 (scalar) Wall F ilm M ass WallFilmTemperature (scalar) Wall F ilm Temp erature WallFilmVelocity (vector) Wall F ilm %s-V elocity WallFilmVelocityMagnitude (scalar) Wall F ilm Velocity Magnitude WallIrradiationFluxNormalizedStdDeviation (scalar)Wall Ir radia tion F lux.N ormaliz ed S td Deviation WallTemperature (scalar) Wall Temp erature WallTemperatureShellCellThin (scalar) Wall Temp erature (Shell C ell/T hin) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 700Fluen t Expr essions LanguageVariable (t ype) Descr iption WallTemperatureThin (scalar) Wall Temp erature (Thin) WallYplus (scalar) Wall Yplus WallYstar (scalar) Wall Ystar XFaceArea (scalar) X Face Area XVelocityMeshSmoothing (scalar) X Velocity Mesh S moothing YFaceArea (scalar) Y Face Area YVelocityMeshSmoothing (scalar) Y Velocity Mesh S moothing ZFaceArea (scalar) Z Face Area ZVelocityMeshSmoothing (scalar) Z Velocity Mesh S moothing dHd (vector) dH-d%s dMassFractiondx (scalar with sp ecies) dMass F raction %s-dx dMassFractiondy (scalar with sp ecies) dMass F raction %s-d y dMassFractiondz (scalar with sp ecies) dMass F raction %s-dz dSDRd (vector) dSDR/d%s dTEDd (vector) dTED/d%s dTKEd (vector) dTKE/d%s dTd (vector) dT-d%s dVelocitydz (vector) d%s-V elocity/dz ded (vector) de-d%s dkd (vector) dk-d%s dnutd (vector) dnut-d%s dpd (vector) dp-d%s dpdt (scalar) dp-dt drhod (vector) drho-d%s dvofd (vector) dvof-d%s log10ShapeSensitivityMagnitude (scalar) log10(S hap e Sensitivit y Magnitude) 701Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Appendix: Supp orted F ield VariablesRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 702Chapt er 6: Reading and M anipula ting M eshes ANSY S Fluen t can imp ort diff erent types of meshes fr om v arious sour ces.You c an mo dify the mesh b y transla ting or sc aling no de c oordina tes, par titioning the domain f or par allel pr ocessing , and mer ging or separ ating z ones .You c an c onvert all 3D meshes t o polyhedr al cells, except f or pur e he x meshes . Hexahedr al cells ar e pr eser ved dur ing c onversion. You c an also obtain diagnostic inf ormation on the mesh, including memor y usage and simple x, topological, and domain inf ormation. You c an find out the numb er of no des, faces, and c ells in the mesh, det ermine the minimum and maximum c ell v olumes in the domain, and check f or the pr oper numb ers of no des and fac es p er cell.These and other c apabil- ities ar e descr ibed in the f ollowing sec tions . 6.1. Mesh Topologies 6.2. Mesh R equir emen ts and C onsider ations 6.3. Mesh S ources 6.4. Reference Frames 6.5. Non-C onformal M eshes 6.6. Overset M eshes 6.7. Check ing the M esh 6.8. Reporting M esh S tatistics 6.9. Converting the M esh t o a P olyhedr al M esh 6.10. Modifying the M esh See Adapting the M esh (p.2705 ) for inf ormation ab out adapting the mesh based on solution da ta and related func tions , and Mesh P artitioning and L oad B alancing (p.3067 ) for details on par titioning the mesh for par allel pr ocessing . 6.1. Mesh Topologies As an unstr uctured solv er, ANSY S Fluen t uses in ternal da ta str uctures to assign an or der t o the c ells, faces, and gr id p oints in a mesh and t o main tain c ontact between adjac ent cells.Therefore, it do es not requir e i,j,k inde xing t o lo cate neighb oring c ells.This giv es y ou the fle xibilit y to use the b est mesh t o- pology for y our pr oblem, as the solv er do es not f orce an o verall str ucture or t opology on the mesh. For 2D meshes , quadr ilateral and tr iangular c ells ar e acc epted, and f or 3D meshes , hexahedr al, tetrahedr al, pyramid , wedge , and p olyhedr al cells c an b e used .Figur e 6.1: Cell Types (p.704) depic ts each of these cell t ypes. Both single-blo ck and multi-blo ck str uctured meshes , as w ell as h ybrid meshes c ontaining quadr ilateral and tr iangular c ells or he xahedr al, tetrahedr al, pyramid , and w edge c ells ar e acc eptable . ANSY S Fluen t also acc epts meshes with hanging no des (tha t is, nodes on edges and fac es tha t are not vertices of all the c ells shar ing those edges or fac es) and hanging edges (tha t is, edges on fac es tha t do not ac t as edges f or b oth of the c ells shar ing those fac es), although y ou ma y need t o remo ve the hanging no des/edges fr om in terior w alls. See Hanging N ode A daption in the Theor y Guide for inf ormation about acc eptable hanging no des, and Remo ving Hanging N odes/E dges (p.731) and Converting C ells with Hanging N odes / E dges t o Polyhedr a (p.801) for details on r emo ving hanging no des/edges . Meshes with non-c onformal b oundar ies (tha t is, meshes with multiple sub domains in which the mesh no de locations a t the in ternal sub domain b oundar ies ar e not iden tical) ar e also acc eptable . For details , see Non-C onformal M eshes (p.741). 703Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Figur e 6.1: Cell Types Some e xamples of meshes tha t are valid f or ANSY S Fluen t are pr esen ted in Examples of A cceptable Mesh Topologies (p.704). Different cell shap es and their fac e-no de c onnec tivit y are explained in Face- Node C onnec tivit y in ANSY S Fluen t (p.709).Choosing the A ppropriate M esh Type (p.716) explains ho w to cho ose the mesh t ype tha t is b est suit ed f or y our pr oblem. 6.1.1. Examples of A cceptable M esh Topologies ANSY S Fluen t can solv e pr oblems on a wide v ariety of meshes .Figur e 6.2: Structured Q uadr ilateral Mesh f or an A irfoil (p.705)-Figur e 6.13: Polyhedr al M esh (p.709) sho w examples of meshes tha t are valid f or ANSY S Fluen t. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 704Reading and M anipula ting M eshesO-type meshes , meshes with z ero-thick ness w alls, C-type meshes , conformal blo ck-str uctured meshes , multiblo ck str uctured meshes , non-c onformal meshes , and unstr uctured tr iangular , tetrahedr al, quad- rilateral, hexahedr al, and p olyhedr al meshes ar e all acc eptable . Note Though ANSY S Fluen t do es not r equir e a c yclic br anch cut in an O-t ype mesh, it will acc ept a mesh tha t contains one . Figur e 6.2: Structured Q uadr ilateral M esh f or an A irfoil Figur e 6.3: Unstr uctured Q uadr ilateral M esh 705Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Mesh TopologiesFigur e 6.4: Multiblo ck S tructured Q uadr ilateral M esh Figur e 6.5: O-T ype Structured Q uadr ilateral M esh Figur e 6.6: Parachut e M odeled With Z ero-Thick ness Wall Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 706Reading and M anipula ting M eshesFigur e 6.7: C-T ype Structured Q uadr ilateral M esh Figur e 6.8: 3D M ultiblo ck S tructured M esh Figur e 6.9: Unstr uctured Triangular M esh f or an A irfoil 707Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Mesh TopologiesFigur e 6.10: Unstr uctured Tetrahedr al M esh Figur e 6.11: Hybr id Triangular/Q uadr ilateral M esh with H anging N odes Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 708Reading and M anipula ting M eshesFigur e 6.12: Non-C onformal H ybr id M esh f or a Rot or-S tator G eometr y Figur e 6.13: Polyhedr al M esh 6.1.2. Face-N ode C onnec tivit y in ANSY S Fluen t This sec tion c ontains inf ormation ab out the c onnec tivit y of fac es and their r elated no des in t erms of node numb er and fac e numb er. Face-no de c onnec tivit y for the f ollowing c ell shap es is e xplained her e: •triangular ( Figur e 6.14: Face and N ode N umb ering f or Triangular C ells (p.710)) •quadr ilateral (Figur e 6.15: Face and N ode N umb ering f or Q uadr ilateral Cells (p.711)) •tetrahedr al (Figur e 6.16: Face and N ode N umb ering f or Tetrahedr al Cells (p.712)) •wedge ( Figur e 6.17: Face and N ode N umb ering f or Wedge C ells (p.713)) •pyramidal ( Figur e 6.18: Face and N ode N umb ering f or P yramidal C ells (p.714)) •hex (Figur e 6.19: Face and N ode N umb ering f or H ex Cells (p.715)) •polyhedr al (Figur e 6.20: An Example of a P olyhedr al Cell (p.716)) This inf ormation is useful in in terfacing with ANSY S Fluen t. 709Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Mesh Topologies6.1.2.1. Face-N ode C onnec tivit y for Triangular C ells Figur e 6.14: Face and N ode N umb ering f or Triangular C ells Associated N odes Face 1-2 Face 1 2-3 Face 2 3-1 Face 3 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 710Reading and M anipula ting M eshes6.1.2.2. Face-N ode C onnec tivit y for Q uadrilat eral C ells Figur e 6.15: Face and N ode N umb ering f or Q uadr ilateral C ells Associated N odes Face 1-2 Face 1 2-3 Face 2 3-4 Face 3 4-1 Face 4 711Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Mesh Topologies6.1.2.3. Face-N ode C onnec tivit y for Tetrahedr al C ells Figur e 6.16: Face and N ode N umb ering f or Tetrahedr al C ells Associated N odes Face 4-3-2 Face 1 3-4-1 Face 2 2-1-4 Face 3 3-1-2 Face 4 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 712Reading and M anipula ting M eshes6.1.2.4. Face-N ode C onnec tivit y for Wedge C ells Figur e 6.17: Face and N ode N umb ering f or Wedge C ells Associated N odes Face 1-2-3 Face 1 1-4-5-2 Face 2 2-5-6-3 Face 3 3-6-4-1 Face 4 4-6-5 Face 5 713Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Mesh Topologies6.1.2.5. Face-N ode C onnec tivit y for P yramidal C ells Figur e 6.18: Face and N ode N umb ering f or P yramidal C ells Associated N odes Face 1-2-3-4 Face 1 1-5-2 Face 2 2-5-3 Face 3 3-5-4 Face 4 4-5-1 Face 5 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 714Reading and M anipula ting M eshes6.1.2.6. Face-N ode C onnec tivit y for H ex Cells Figur e 6.19: Face and N ode N umb ering f or H ex Cells Associated N odes Face 1-2-3-4 Face 1 1-5-6-2 Face 2 2-6-7-3 Face 3 4-3-7-8 Face 4 1-4-8-5 Face 5 5-8-7-6 Face 6 715Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Mesh Topologies6.1.2.7. Face-N ode C onnec tivit y for P olyhedr al C ells Figur e 6.20: An Example of a P olyhedr al C ell For p olyhedr al cells, ther e is no e xplicit fac e and no de numb ering as with the other c ell t ypes. 6.1.3. Choosing the A ppr opr iate M esh Type ANSY S Fluen t can use meshes c omp osed of tr iangular or quadr ilateral cells (or a c ombina tion of the two) in 2D , and t etrahedr al, hexahedr al, polyhedr al, pyramid , or w edge c ells (or a c ombina tion of these) in 3D .The choic e of which mesh t ype to use will dep end on y our applic ation. When cho osing mesh type, consider the f ollowing issues: •setup time •computa tional e xpense •numer ical diffusion 6.1.3.1. Setup Time Many flo w pr oblems solv ed in engineer ing pr actice involve comple x geometr ies.The cr eation of structured or blo ck-str uctured meshes (c onsisting of quadr ilateral or he xahedr al elemen ts) f or such problems c an b e extremely time-c onsuming if not imp ossible .Therefore, setup time f or c omple x geometr ies is the major motiv ation f or using unstr uctured meshes emplo ying tr iangular or t etrahedr al cells. However, if y our geometr y is r elatively simple , ther e ma y be no sa ving in setup time with either appr oach. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 716Reading and M anipula ting M eshesOther r isks of using str uctured or blo ck-str uctured meshes with c omplic ated geometr ies include the oversimplific ation of the geometr y, mesh qualit y issues , and a less efficien t mesh distr ibution (f or example , fine r esolution in ar eas of less imp ortanc e) tha t results in a high c ell c oun t. If you alr eady ha ve a mesh cr eated f or a str uctured c ode, it will sa ve you time t o use this mesh in ANSY S Fluen t rather than r egener ate it. This c an b e a motiv ation f or using quadr ilateral or he xahedr al cells in y our ANSY S Fluen t simula tion. Note ANSY S Fluen t has a r ange of filt ers tha t allo w you t o imp ort str uctured meshes fr om other codes, including FL UENT 4. For details , see Mesh S ources (p.723). 6.1.3.2. Computational E xpense When geometr ies ar e comple x or the r ange of length sc ales of the flo w is lar ge, a tr iangular/t etrahedr al mesh c an b e created with far f ewer cells than the equiv alen t mesh c onsisting of quadr ilateral/he xa- hedr al elemen ts.This is b ecause a tr iangular/t etrahedr al mesh allo ws clust ering of c ells in selec ted regions of the flo w domain. Structured quadr ilateral/he xahedr al meshes will gener ally f orce cells t o be plac ed in r egions wher e the y are not needed . Unstr uctured quadr ilateral/he xahedr al meshes off er man y of the ad vantages of tr iangular/t etrahedr al meshes f or mo derately-c omple x geometr ies. A char acteristic of quadr ilateral/he xahedr al elemen ts tha t migh t mak e them mor e ec onomic al in some situa tions is tha t the y permit a much lar ger asp ect ratio than tr iangular/t etrahedr al cells. A lar ge asp ect ratio in a tr iangular/t etrahedr al cell will in variably aff ect the sk ewness of the c ell, which is undesir able as it ma y imp ede accur acy and c onvergenc e.Therefore, if y ou ha ve a r elatively simple geometr y in which the flo w conforms w ell t o the shap e of the geometr y, such as a long thin duc t, use a mesh of high-asp ect-ratio quadr ilateral/he xahedr al cells.The mesh is lik ely t o ha ve far f ewer cells than if y ou use tr iangular/t etrahedr al cells. Converting the en tire domain of y our (t etrahedr al) mesh t o a p olyhedr al mesh will r esult in a lo wer cell c oun t than y our or iginal mesh. Although the r esult is a c oarser mesh, convergenc e will gener ally be fast er, possibly sa ving y ou some c omputa tional e xpense . In summar y, the f ollowing pr actices ar e gener ally r ecommended: •For simple geometr ies, use quadr ilateral/he xahedr al meshes . •For mo derately c omple x geometr ies, use unstr uctured quadr ilateral/he xahedr al meshes . •For relatively c omple x geometr ies, use tr iangular/t etrahedr al meshes with w edge elemen ts in the boundar y layers. •For e xtremely c omple x geometr ies, use pur e triangular/t etrahedr al meshes . 6.1.3.3. Numeric al D iffusion A dominan t sour ce of er ror in multidimensional situa tions is numer ical diffusion (false diffusion). The term false diffusion is used b ecause the diffusion is not a r eal phenomenon, yet its eff ect on a flo w calcula tion is analo gous t o tha t of incr easing the r eal diffusion c oefficien t. The f ollowing c ommen ts can b e made ab out numer ical diffusion: 717Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Mesh Topologies•Numer ical diffusion is most notic eable when the r eal diffusion is small, tha t is, when the situa tion is c on- vection-domina ted. •All pr actical numer ical schemes f or solving fluid flo w contain a finit e amoun t of numer ical diffusion. This is because numer ical diffusion ar ises fr om tr uncation er rors tha t are a c onsequenc e of r epresen ting the fluid flo w equa tions in discr ete form. •The sec ond-or der and the MUSCL discr etiza tion scheme used in ANSY S Fluen t can help r educ e the eff ects of numer ical diffusion on the solution. •The amoun t of numer ical diffusion is in versely r elated t o the r esolution of the mesh. Therefore, one w ay of dealing with numer ical diffusion is t o refine the mesh. •Numer ical diffusion is minimiz ed when the flo w is aligned with the mesh. This is the most r elevant to the choic e of the mesh. If you use a tr iangular/t etrahedr al mesh, the flow can never be aligned with the mesh. If you use a quadr ilateral/he xahedr al mesh, this situa tion migh t occur , but not f or c omple x flo ws. It is only in a simple flow, such as the flo w thr ough a long duc t, in which y ou c an r ely on a quadr ilateral/he xahedr al mesh t o minimiz e numer ical diffusion. In such situa tions , it is ad vantageous t o use a quadr ilateral/he xahedr al mesh, sinc e you will b e able to get a b etter solution with f ewer cells than if y ou w ere using a tr iangular/t etrahedr al mesh. •If you w ould lik e higher r esolution f or a gr adien t tha t is p erpendicular t o a w all, you c an cr eate pr ism layers with higher asp ect ratios near the w all. 6.2. Mesh Requir emen ts and C onsider ations This sec tion c ontains inf ormation ab out sp ecial geometr y/mesh r equir emen ts and gener al commen ts on mesh qualit y. 6.2.1. Geometr y/M esh R equir emen ts 6.2.2. Mesh Q ualit y 6.2.1. Geometr y/M esh Requir emen ts You should b e aware of the f ollowing geometr y setup and mesh c onstr uction r equir emen ts at the beginning of y our pr oblem setup: •Axisymmetr ic geometr ies must b e defined such tha t the axis of r otation is the axis of the C artesian c o- ordina tes used t o define the geometr y (Figur e 6.21: Setup of A xisymmetr ic G eometr ies with the x A xis as the C enterline (p.719)). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 718Reading and M anipula ting M eshesFigur e 6.21: Setup of A xisymmetr ic G eometr ies with the x A xis as the C enterline •ANSY S Fluen t allo ws you t o set up p eriodic b oundar ies using either c onformal or non-c onformal p eriodic zones . For conformal p eriodic b oundar ies, the p eriodic z ones must ha ve iden tical meshes . The c onformal p eriodic b oundar y zones c an b e created in the meshing mo de of F luen t or GAMBIT when y ou ar e gener ating the v olume mesh. See the F luen t Meshing sec tion of the U ser’s Guide or the GAMBIT M odeling G uide f or mor e inf ormation. Although F luen t to cr eate periodic b oundar ies tha t are conformal, as w ell as p eriodic in terfaces tha t are non-c onformal; the la tter is nec essar y if y ou cr eated y our mesh using a C AD pack age tha t is not able t o pr oduce true p eriodic b oundar ies. For details on cr eating such in terfaces, see Creating P eri- odic Z ones and In terfaces (p.811). 6.2.2. Mesh Q ualit y The qualit y of the mesh pla ys a signific ant role in the accur acy and stabilit y of the numer ical compu- tation. Regar dless of the t ype of mesh used in y our domain, check ing the qualit y of y our mesh is es- sential. One imp ortant indic ator of mesh qualit y tha t ANSY S Fluen t allo ws you t o check is a quan tity referred t o as the or thogonalit y. In or der t o det ermine the or thogonalit y of a giv en c ell, the f ollowing quan tities ar e calcula ted f or each fac e : •the nor maliz ed dot pr oduc t of the ar ea v ector of a fac e ( ) and a v ector fr om the c entroid of the c ell to the c entroid of tha t fac e ( ): (6.1) •the nor maliz ed dot pr oduc t of the ar ea v ector of a fac e ( ) and a v ector fr om the c entroid of the c ell to the c entroid of the adjac ent cell tha t shar es tha t fac e ( ): (6.2) The minimum v alue tha t results fr om c alcula ting Equa tion 6.1 (p.719) and Equa tion 6.2 (p.719) for all of the fac es is then defined as the or thogonalit y for the c ell.Therefore, the w orst c ells will ha ve an 719Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Mesh R equir emen ts and C onsider ationsorthogonalit y closer t o 0 and the b est c ells will ha ve an or thogonalit y closer t o 1. Figur e 6.22: The Vectors U sed t o Comput e Or thogonalit y (p.720) illustr ates the r elevant vectors. Figur e 6.22: The Vectors U sed t o Comput e Or tho gonalit y Orthogonal Q ualit y dep ends on c ell t ype: •For tetrahedr al, prism, and p yramid c ells, the Or thogonal Q ualit y is the minimum of the or thogonalit y and (1- c ell sk ewness). •For he xahedr al and p olyhedr al cells, the Or thogonal Q ualit y is the same as the or thogonalit y. Another imp ortant indic ator of the mesh qualit y is the asp ect ratio.The asp ect ratio is a measur e of the str etching of a c ell. It is c omput ed as the r atio of the maximum v alue t o the minimum v alue of any of the f ollowing distanc es: the nor mal distanc es b etween the c ell c entroid and fac e centroids (comput ed as a dot pr oduc t of the distanc e vector and the fac e nor mal), and the distanc es b etween the c ell c entroid and no des. For a unit cub e (see Figur e 6.23: Calcula ting the A spect Ratio f or a U nit Cube (p.721)), the maximum distanc e is 0.866, and the minimum distanc e is 0.5, so the asp ect ratio is 1.732. This t ype of definition c an b e applied on an y type of mesh, including p olyhedr al. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 720Reading and M anipula ting M eshesFigur e 6.23: Calcula ting the A spect Ratio f or a U nit C ube To check the qualit y of y our mesh, you c an use the Rep ort Qualit y butt on in the Gener al task page: Setup → Gener al → Rep ort Qualit y A message will b e displa yed in the c onsole , such as the e xample tha t follows: Mesh Quality: Orthogonal Quality ranges from 0 to 1, where values close to 0 correspond to low quality. Minimum Orthogonal Quality = 6.07960e-01 Maximum Aspect Ratio = 5.42664e+00 If you w ould lik e mor e inf ormation ab out the qualit y displa yed in the c onsole (including additional qualit y metr ics and the z ones tha t ha ve the c ells with the lo west qualit y), set the mesh/check- verbosity text command t o 2 (valid v alues ar e 0,1,2) prior t o using the Rep ort Qualit y butt on. For inf ormation ab out ho w to impr ove poor qualit y cells, see Repair ing M eshes (p.790). When e valua ting whether the qualit y of y our mesh is sufficien t for the pr oblem y ou ar e mo deling , it is imp ortant to consider a ttribut es such as mesh elemen t distr ibution, cell shap e, smo othness , and flow-field dep endenc y.These a ttribut es ar e descr ibed in the sec tions tha t follow. 6.2.2.1. Mesh Element D istribution Since you ar e discr etely defining a c ontinuous domain, the degr ee t o which the salien t features of the flo w (such as shear la yers, separ ated r egions , sho ck w aves, boundar y layers, and mixing z ones) are resolv ed dep ends on the densit y and distr ibution of mesh elemen ts. In man y cases , poor resolution in cr itical regions c an dr ama tically aff ect results . For e xample , the pr edic tion of separ ation due t o an adverse pr essur e gr adien t dep ends hea vily on the r esolution of the b oundar y layer upstr eam of the point of separ ation. Resolution of the b oundar y layer (tha t is, mesh spacing near w alls) also pla ys a signific ant role in the accur acy of the c omput ed w all shear str ess and hea t transf er coefficien t.This is par ticular ly tr ue in laminar flo ws wher e the mesh adjac ent to the w all should ob ey 721Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Mesh R equir emen ts and C onsider ations(6.3) wher e = distanc e to the w all fr om the adjac ent cell c entroid = fr ee-str eam v elocity = k inema tic visc osity of the fluid = distanc e along the w all fr om the star ting p oint of the b oundar y layer Equa tion 6.3 (p.722) is based up on the B lasius solution f or laminar flo w over a fla t pla te at zero incid- ence [110] (p.4011 ). Proper resolution of the mesh f or turbulen t flo ws is also v ery imp ortant. Due t o the str ong in teraction of the mean flo w and turbulenc e, the numer ical results f or turbulen t flo ws tend t o be mor e susc eptible to mesh elemen t distr ibution than those f or laminar flo ws. In the near-w all region, diff erent mesh resolutions ar e requir ed dep ending on the near-w all mo del b eing used . See Model Hier archy (p.1391 ) for guidelines . In gener al, no flo w passage should b e represen ted b y fewer than 5 c ells. Most c ases will r equir e man y mor e cells t o adequa tely r esolv e the passage . In r egions of lar ge gr adien ts, as in shear la yers or mixing zones , the mesh should b e fine enough t o minimiz e the change in the flo w variables fr om c ell t o cell. Unfortuna tely, it is v ery difficult t o det ermine the lo cations of imp ortant flo w features in ad vance. Moreover, the mesh r esolution in most c omplic ated 3D flo w fields will b e constr ained b y CPU time and c omput er resour ce limita tions (tha t is, memor y and disk spac e). Although accur acy incr eases with larger meshes , the CPU and memor y requir emen ts to comput e the solution and p ostpr ocess the results also incr ease . Solution-adaptiv e mesh r efinemen t can b e used t o incr ease and/or decr ease mesh densit y based on the e volving flo w field , and ther efore pr ovides the p otential f or mor e ec onom- ical use of gr id p oints (and henc e reduc ed time and r esour ce requir emen ts). See Adapting the Mesh (p.2705 ) for inf ormation on solution adaption. 6.2.2.2. Cell Q ualit y The qualit y of the c ell (including its or thogonal qualit y, asp ect ratio, and sk ewness) also has a signi- ficant impac t on the accur acy of the numer ical solution. •Ortho gonal qualit y is comput ed f or cells using c ell sk ewness and the v ector fr om the c ell c entroid t o each of its fac es, the c orresponding fac e area v ector, and the v ector fr om the c ell c entroid t o the c entroids of each of the adjac ent cells (see Equa tion 6.1 (p.719),Equa tion 6.2 (p.719), and Figur e 6.22: The Vectors U sed to Comput e Or thogonalit y (p.720)).The w orst c ells will ha ve an or thogonal qualit y closer t o 0, with the best c ells closer t o 1. The minimum or thogonal qualit y for all t ypes of c ells should b e mor e than 0.01, with an a verage v alue tha t is signific antly higher . •Aspect ratio is a measur e of the str etching of the c ell. As discussed in Computa tional Exp ense (p.717), for highly anisotr opic flo ws, extreme asp ect ratios ma y yield accur ate results with f ewer cells. Gener ally, it is best t o avoid sudden and lar ge changes in c ell asp ect ratios in ar eas wher e the flo w field e xhibit lar ge changes or str ong gr adien ts. •Skewness is defined as the diff erence between the shap e of the c ell and the shap e of an equila teral cell of equiv alen t volume . Highly sk ewed c ells c an decr ease accur acy and destabiliz e the solution. For e xample , optimal quadr ilateral meshes will ha ve vertex angles close t o 90 degr ees, while tr iangular meshes should preferably ha ve angles of close t o 60 degr ees and ha ve all angles less than 90 degr ees. A gener al rule is Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 722Reading and M anipula ting M eshesthat the maximum sk ewness f or a tr iangular/t etrahedr al mesh in most flo ws should b e kept b elow 0.95, with an a verage v alue tha t is signific antly lo wer. A maximum v alue ab ove 0.95 ma y lead t o convergenc e difficulties and ma y requir e changing the solv er controls, such as r educing under-r elaxa tion fac tors and/or swit ching t o the pr essur e-based c oupled solv er. Cell siz e change and fac e warp ar e additional qualit y measur e tha t could aff ect stabilit y and accur acy. See the F luen t Meshing sec tion of the U ser’s Guide f or mor e details . 6.2.2.3. Smo othness Truncation er ror is the diff erence between the par tial der ivatives in the go verning equa tions and their discr ete appr oxima tions . Rapid changes in c ell v olume b etween adjac ent cells tr ansla te in to lar ger truncation er rors. ANSY S Fluen t provides the c apabilit y to impr ove the smo othness b y refining the mesh based on the change in c ell v olume or the gr adien t of c ell v olume . For inf ormation on mar king cells b y cell v olume and then r efining the mesh, see Volume (p.2767 ) and Refining and C oarsen- ing (p.2708 ). 6.2.2.4. Flow-F ield D ependenc y The eff ect of r esolution, smo othness , and c ell shap e on the accur acy and stabilit y of the solution process is dep enden t on the flo w field b eing simula ted. For e xample , very sk ewed c ells c an b e toler ated in b enign flo w regions , but c an b e very damaging in r egions with str ong flo w gr adien ts. Since the lo cations of str ong flo w gr adien ts gener ally c annot b e det ermined a pr iori, you should str ive to achie ve a high-qualit y mesh o ver the en tire flo w domain. 6.3. Mesh S our ces Since ANSY S Fluen t can handle a numb er of diff erent mesh t opologies , ther e ar e man y sour ces fr om which y ou c an obtain a mesh t o be used in y our simula tion. You c an gener ate a mesh using ANSY S Meshing , the meshing mo de of F luen t, Fluen t Meshing , GAMBIT , GeoM esh, PreBFC, ICEM CFD , I-deas , NASTR AN, PATRAN, ARIES, Mechanic al APDL, CFX, or other pr eprocessors .You c an also use the mesh contained in a F luen t/UNS, RAMP ANT , or FL UENT 4 c ase file .You c an also pr epar e multiple mesh files and c ombine them t o cr eate a single mesh. 6.3.1. ANSY S Meshing M esh F iles 6.3.2. Fluen t Meshing M ode M esh F iles 6.3.3. Fluen t Meshing M esh F iles 6.3.4. GAMBIT M esh F iles 6.3.5. GeoM esh M esh F iles 6.3.6. PreBFC M esh F iles 6.3.7. ICEM CFD M esh F iles 6.3.8. I-deas U niversal F iles 6.3.9. NASTR AN F iles 6.3.10. PATRAN N eutr al Files 6.3.11. Mechanic al APDL F iles 6.3.12. CFX F iles 6.3.13. Using the f e2ram F ilter to Convert Files 6.3.14. Remo ving Hanging N odes/E dges 6.3.15. Fluen t/UNS and R AMP ANT C ase F iles 6.3.16. FLUENT 4 C ase F iles 6.3.17. ANSY S FIDAP N eutr al Files 723Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Mesh S ources6.3.18. Reading M ultiple M esh/C ase/D ata Files 6.3.19. Reading Sur face Mesh F iles 6.3.1. ANSY S M eshing M esh F iles You c an use ANSY S M eshing t o cr eate your mesh. Follow the meshing pr ocedur e and e xport to the ANSY S Fluen t mesh f ormat (see Fluen t Mesh Exp ort in the ANSY S M eshing U ser’s Guide for details). To imp ort the mesh in to Fluen t, use the File/Read/M esh... ribbon tab it em (as descr ibed in Reading Mesh F iles (p.586)). 6.3.2. Fluen t Meshing M ode M esh F iles You c an use the meshing mo de of F luen t (which w as pr eviously a stand-alone pr ogram named F luen t Meshing) t o cr eate 3D unstr uctured tr iangular/t etrahedr al meshes fr om b oundar y or sur face meshes . Switch t o meshing mo de and then f ollow the meshing pr ocedur e descr ibed in the F luen t Meshing section of the U ser’s Guide .You c an sa ve your mesh using the File/W rite/M esh... menu it em. Then swit ch t o the solution mo de t o set up the c ase file f or the tr ansf erred mesh, or imp ort the sa ved mesh in to a new F luen t session using the File/Read/M esh... ribbon tab it em (as descr ibed in Reading Mesh F iles (p.586)). For inf ormation ab out swit ching b etween meshing and solution mo des, see Switching B etween Meshing and S olution M odes (p.59) in the Getting S tarted G uide . 6.3.3. Fluen t Meshing M esh F iles Prior t o version 14.5, Fluen t Meshing w as a stand-alone pr oduc t tha t was used t o cr eate 3D unstr uctured triangular/t etrahedr al meshes fr om b oundar y or sur face meshes . Fluen t Meshing has b een in tegrated as the F luen t meshing mo de.To imp ort meshes cr eated b y Fluen t Meshing in to Fluen t, use the File/Read/M esh... ribbon tab it em (as descr ibed in Reading M esh F iles (p.586)). 6.3.4. GAMBIT M esh F iles You c an use GAMBIT t o cr eate 2D and 3D str uctured/unstr uctured/h ybrid meshes .To cr eate an y of these meshes f or ANSY S Fluen t, follow the pr ocedur e descr ibed in the GAMBIT M odeling G uide , and export your mesh in F luen t 5/6 f ormat. All such meshes c an b e imp orted dir ectly in to ANSY S Fluen t using the File/Read/M esh... ribbon tab it em, as descr ibed in Reading M esh F iles (p.586). 6.3.5. GeoM esh M esh F iles You c an use G eoM esh t o cr eate complet e 2D quadr ilateral or tr iangular meshes , 3D he xahedr al meshes , and tr iangular sur face meshes f or 3D t etrahedr al meshes .To cr eate an y of these meshes f or ANSY S Fluen t, follow the pr ocedur e descr ibed in the G eoM esh U ser's G uide . To complet e the gener ation of a 3D t etrahedr al mesh, read the sur face mesh in to the meshing mo de of F luen t and gener ate the v olume mesh ther e (see the F luen t Meshing sec tion of the U ser’s Guide for details). All other meshes c an b e read dir ectly in to the solution mo de of F luen t. Use the File/Read/M esh... ribbon tab it em t o read the mesh files , as descr ibed in Reading M esh F iles (p.586). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 724Reading and M anipula ting M eshes6.3.6. PreBFC M esh F iles You c an use P reBFC t o cr eate two diff erent types of meshes f or ANSY S Fluen t, structured quadr ilater- al/he xahedr al and unstr uctured tr iangular/t etrahedr al. 6.3.6.1. Struc tured Mesh F iles To gener ate a str uctured 2D or 3D mesh, follow the pr ocedur e descr ibed in the P reBFC U ser's Guide (C hapt ers 6 and 7). The r esulting mesh will c ontain quadr ilateral (2D) or he xahedr al (3D) elemen ts. Do not sp ecify mor e than 70 w all z ones and 35 inlet z ones . To imp ort the mesh, use the File/Imp ort/PreBFC F ile... ribbon tab it em, as descr ibed in PreBFC Files (p.610). To manually c onvert a file in P reBFC f ormat to a mesh file suitable f or ANSY S Fluen t, enter the f ollowing command: utility fl42seg input_filename output_filename The output file pr oduced c an b e read in to ANSY S Fluen t using the File/Read/M esh... ribbon tab it em, as descr ibed in Reading M esh F iles (p.586). 6.3.6.2. Unstruc tured Triangular and Tetrahedr al Mesh F iles To gener ate an unstr uctured 2D mesh, follow the pr ocedur e descr ibed in the P reBFC U ser's G uide . Save the mesh file in the R AMP ANT f ormat using the MESH-RAMPANT/TGRID command .The cur rent ANSY S Fluen t format is the same as the R AMP ANT f ormat.The r esulting mesh will c ontain tr iangular elemen ts.To imp ort the mesh, use the File/Read/M esh... ribbon tab it em, as descr ibed in Reading Mesh F iles (p.586). To gener ate a 3D unstr uctured t etrahedr al mesh, follow the pr ocedur e descr ibed in C hapt er 8 of the PreBFC U ser's G uide f or gener ating a sur face mesh. Then r ead the sur face mesh in to the meshing mode of F luen t, and c omplet e the mesh gener ation ther e. See the F luen t Meshing sec tion of the User’s Guide f or details . 6.3.7. ICEM CFD M esh F iles You c an use ICEM CFD t o cr eate str uctured meshes in FL UENT 4 f ormat and unstr uctured meshes in RAMP ANT f ormat. •To imp ort a FL UENT 4 mesh, follow the instr uctions in FLUENT 4 C ase F iles (p.732). •To imp ort a R AMP ANT mesh, use the File/Read/M esh... ribbon tab it em, as descr ibed in Reading M esh Files (p.586). The cur rent ANSY S Fluen t format is the same as the R AMP ANT f ormat,not the FL UENT 4 f ormat. After reading a tr iangular or t etrahedr al ICEM CFD v olume mesh, impr ove its qualit y thr ough smo othing (as descr ibed in Qualit y-Based S moothing (p.827)). 6.3.8. I-deas U niversal F iles You c an imp ort an I-deas U niversal file in to ANSY S Fluen t in thr ee diff erent ways. 725Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Mesh S ources•Gener ate an I-deas sur face or v olume mesh c ontaining tr iangular , quadr ilateral, tetrahedr al, wedge and/or hexahedr al elemen ts. Imp ort it in to the meshing mo de of F luen t using the c ommands descr ibed in the Fluen t Meshing sec tion of the U ser’s Guide . Adher e to the r estrictions descr ibed in Appendix B: Mesh F ile Format (p.511) in the F luen t Meshing sec tion of the U ser’s Guide . In meshing mo de, complet e the mesh gener ation (if nec essar y); then y ou c an swit ch to the solution mo de of F luen t or r ead it in to a new F luen t session as descr ibed in Fluen t Meshing M ode M esh F iles (p.724). •Gener ate an I-deas v olume mesh with linear tr iangular , quadr ilateral, tetrahedr al, wedge , or he xahedr al elemen ts. Imp ort it dir ectly using the File/Imp ort/I-deas U niversal... ribbon tab it em, as descr ibed in I- deas U niversal F iles (p.607). •Gener ate an I-deas v olume mesh with linear tr iangular , quadr ilateral, tetrahedr al, wedge , or he xahedr al elemen ts. Use the fe2ram filter to convert the U niversal file t o the f ormat used b y ANSY S Fluen t.To convert an input file in I-deas U niversal f ormat to an output file in ANSY S Fluen t format, follow the instr uctions below in Using the f e2ram F ilter to Convert Files (p.731). After the output file is wr itten, read it in to ANSY S Fluen t using the File/Read/M esh... ribbon tab it em, as descr ibed in Reading M esh F iles (p.586). 6.3.8.1. Recogniz ed I-deas D atasets The f ollowing U niversal file da tasets ar e recogniz ed b y the ANSY S Fluen t mesh imp ort utilit y: •Node C oordina tes dataset numb er 15, 781, 2411 •Elemen ts dataset numb er 71, 780, 2412 •Permanen t Groups dataset numb er 752, 2417, 2429, 2430, 2432, 2435 For 2D v olume meshes , the elemen ts must e xist in a c onstan t plane . Note The mesh ar ea or mesh v olume da tasets ar e not recogniz ed.This implies tha t wr iting multiple mesh ar eas/v olumes t o a single U niversal file ma y confuse ANSY S Fluen t. 6.3.8.2. Grouping N odes t o Creat e Face Zones Nodes ar e gr oup ed in I-deas using the Group command t o cr eate boundar y fac e zones . In ANSY S Fluen t, boundar y conditions ar e applied t o each z one . Faces tha t contain the no des in a gr oup ar e gather ed in to a single z one . It is imp ortant not t o gr oup no des of in ternal fac es with no des of boundar y fac es. One t echnique is t o gener ate gr oups aut oma tically based on cur ves or mesh ar eas—tha t is, every curve or mesh ar ea will b e a diff erent zone in ANSY S Fluen t.You ma y also cr eate the gr oups manually , gener ating gr oups c onsisting of all no des r elated t o a giv en cur ve (2D) or mesh ar ea (3D). 6.3.8.3. Grouping Elements t o Creat e Cell Z ones Elemen ts in I-deas ar e gr oup ed using the Group command t o cr eate the multiple c ell z ones . All ele- men ts gr oup ed t ogether ar e plac ed in a single c ell z one in ANSY S Fluen t. If the elemen ts ar e not group ed, ANSY S Fluen t will plac e all the c ells in to a single z one . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 726Reading and M anipula ting M eshes6.3.8.4. Deleting D uplic ate Nodes I-deas ma y gener ate duplic ate or c oinciden t no des in the pr ocess of cr eating elemen ts.These no des must b e remo ved in I-deas b efore wr iting the univ ersal file f or imp ort into ANSY S Fluen t. 6.3.9. NASTR AN F iles There ar e thr ee diff erent ways in which y ou c an imp ort a NASTR AN file in to ANSY S Fluen t: •You c an gener ate a NASTR AN sur face or v olume mesh c ontaining tr iangular , quadr ilateral, tetrahedr al, wedge , and/or he xahedr al elemen ts, and imp ort it in to the meshing mo de of F luen t using the c ommands descr ibed in the F luen t Meshing sec tion of the U ser’s Guide . Adher e to the r estrictions descr ibed in Ap- pendix B: Mesh F ile F ormat (p.511) in the F luen t Meshing sec tion of the U ser’s Guide . In meshing mo de, complet e the mesh gener ation (if nec essar y); then y ou c an swit ch to the solution mo de of F luen t or r ead it in to a new F luen t session as descr ibed in Fluen t Meshing M ode M esh F iles (p.724). •You c an gener ate a NASTR AN v olume mesh with linear tr iangular , quadr ilateral, tetrahedr al, wedge , or hexahedr al elemen ts, and imp ort it dir ectly using the File/Imp ort/NASTR AN ribbon tab it em, as descr ibed in NASTR AN F iles (p.608). •You c an gener ate a NASTR AN v olume mesh with linear tr iangular , quadr ilateral, tetrahedr al, wedge , or hexahedr al elemen ts.Then use the fe2ram filter to convert the NASTR AN file t o the f ormat used b y ANSY S Fluen t.To convert an input file in NASTR AN f ormat to an output file in ANSY S Fluen t format, follow the in- structions b elow in Using the f e2ram F ilter to Convert Files (p.731). After the output file has b een wr itten, you c an r ead it in to ANSY S Fluen t using the File/Read/M esh... ribbon tab it em, as descr ibed in Reading Mesh F iles (p.586). After reading a tr iangular or t etrahedr al NASTR AN v olume mesh using the la tter metho ds, impr ove its qualit y thr ough smo othing (as descr ibed in Qualit y-Based S moothing (p.827)). 6.3.9.1. Recogniz ed NASTR AN Bulk D ata E ntries The f ollowing NASTR AN file da tasets ar e recogniz ed b y the ANSY S Fluen t mesh imp ort utilit y: •GRID single-pr ecision no de c oordina tes •GRID* double-pr ecision no de c oordina tes •CBAR line elemen ts •CTETR A, CTRIA3 tetrahedr al and tr iangular elemen ts •CHEX A, CQUAD4, CPENT A hexahedr al, quadr ilateral, and w edge elemen ts For 2D v olume meshes , the elemen ts must e xist in a c onstan t plane . 6.3.9.2. Deleting D uplic ate Nodes NASTR AN ma y gener ate duplic ate or c oinciden t no des in the pr ocess of cr eating elemen ts.These nodes must b e remo ved in NASTR AN b efore wr iting the file f or imp ort into ANSY S Fluen t. 727Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Mesh S ources6.3.10. PATRAN N eutr al Files There ar e thr ee diff erent ways in which y ou c an imp ort a P ATRAN N eutr al file in to ANSY S Fluen t. •You c an gener ate a P ATRAN sur face or v olume mesh c ontaining tr iangular , quadr ilateral, tetrahedr al, wedge , and/or he xahedr al elemen ts, and imp ort it in to the meshing mo de of F luen t using the c ommands descr ibed in the F luen t Meshing sec tion of the U ser’s Guide . Adher e to the r estrictions descr ibed in Ap- pendix B: Mesh F ile F ormat (p.511) in the F luen t Meshing sec tion of the U ser’s Guide . In meshing mo de, complet e the mesh gener ation (if nec essar y); then y ou c an swit ch to the solution mo de of F luen t or r ead it in to a new F luen t session as descr ibed in Fluen t Meshing M ode M esh F iles (p.724). •You c an gener ate a P ATRAN v olume mesh with linear tr iangular , quadr ilateral, tetrahedr al, wedge , or hexahedr al elemen ts (gr ouping no des with the same c omp onen t-group name) and imp ort it dir ectly t o ANSY S Fluen t by selec ting the File/Imp ort/PATRAN ribbon tab it em, as descr ibed in PATRAN N eut- ral Files (p.609). •You c an gener ate a P ATRAN v olume mesh with linear tr iangular , quadr ilateral, tetrahedr al, wedge , or hexahedr al elemen ts and then use the fe2ram filter to convert the N eutr al file in to the f ormat used b y ANSY S Fluen t.To convert an input file in P ATRAN N eutr al format to an output file in ANSY S Fluen t format, follow the instr uctions b elow in Using the f e2ram F ilter to Convert Files (p.731). After the output file has been wr itten, you c an r ead it in to ANSY S Fluen t using the File/Read/M esh... ribbon tab it em, as descr ibed in Reading M esh F iles (p.586). After reading a tr iangular or t etrahedr al PATRAN v olume mesh using the la tter metho ds, impr ove its qualit y thr ough smo othing (as descr ibed in Qualit y-Based S moothing (p.827)). Imp ortant To retain a z one t ype dur ing P ATRAN N eutr al file imp ort, add the abbr eviated f orm of the “zone-t ype” before the “zone-name ”, as sho wn b elow: Zone N ame f or P ATRAN e xport (zone-t ype) - (z one-name) Zone Type in ANSY S Fluen t m-f-i-z one-name mass-flo w-inlet p-o-z one-name pressur e-outlet fan-z one-name fan v-i-z one-name velocity-inlet p-f-f-z one-name pressur e-far-field solid-z one-name solid fluid-z one-name fluid 6.3.10.1. Recogniz ed P ATRAN D atasets The f ollowing P ATRAN N eutr al file pack et types ar e recogniz ed b y the ANSY S Fluen t mesh imp ort utilit y: •Node D ata Packet Type 01 •Elemen t Data Packet Type 02 •Distribut ed L oad D ata Packet Type 06 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 728Reading and M anipula ting M eshes•Node Temp erature Data Packet Type 10 •Name C omp onen ts Packet Type 21 •File H eader Packet Type 25 For 2D v olume meshes , the elemen ts must e xist in a c onstan t plane . 6.3.10.2. Grouping Elements t o Creat e Cell Z ones Elemen ts ar e gr oup ed in P ATRAN using the Named Component command t o cr eate the multiple cell z ones . All elemen ts gr oup ed t ogether ar e plac ed in a single c ell z one in ANSY S Fluen t. If the elemen ts ar e not gr oup ed, ANSY S Fluen t will plac e all the c ells in to a single z one . 6.3.11. Mechanic al APDL F iles There ar e thr ee diff erent ways in which y ou c an imp ort a M echanic al APDL file in to ANSY S Fluen t. •You c an gener ate a sur face or v olume mesh c ontaining tr iangular , quadr ilateral, tetrahedr al, wedge , or hexahedr al elemen ts using M echanic al APDL or ARIES, and imp ort it in to the meshing mo de of F luen t using the c ommands descr ibed in the F luen t Meshing sec tion of the U ser’s Guide . Adher e to the r estrictions de- scribed in Appendix B: Mesh F ile F ormat (p.511) in the F luen t Meshing sec tion of the U ser’s Guide . In meshing mo de, complet e the mesh gener ation (if nec essar y); then y ou c an swit ch to the solution mo de of Fluen t or r ead it in to a new F luen t session as descr ibed in Fluen t Meshing M ode M esh F iles (p.724). •You c an gener ate a M echanic al APDL v olume mesh with linear tr iangular , quadr ilateral, tetrahedr al, wedge , or he xahedr al elemen ts, as w ell as with higher or der elemen ts lik e 20 no de he xahedr on, SOLID92, and SOLID187. Then imp ort it dir ectly t o ANSY S Fluen t using the File/Imp ort/M echanic al APDL ribbon tab item, as descr ibed in Mechanic al APDL F iles (p.608). The higher or der elements will b e converted t o their c orresp onding linear elements dur ing the imp ort in ANSY S Fluent . •You c an gener ate a M echanic al APDL v olume mesh with linear tr iangular , quadr ilateral, tetrahedr al, wedge , or he xahedr al elemen ts, and then use the fe2ram filter to convert the M echanic al APDL file in to the f ormat used b y ANSY S Fluen t.To convert an input file in ANSY S 5.4 or 5.5 f ormat to an output file in ANSY S Flu- ent format, follow the instr uctions in Using the f e2ram F ilter to Convert Files (p.731). After the output file has b een wr itten, you c an r ead it in to ANSY S Fluen t using the File/Read/M esh... ribbon tab it em, as descr ibed in Reading M esh F iles (p.586). After reading a tr iangular or t etrahedr al volume mesh using metho d 2 or 3 ab ove, you should impr ove its qualit y thr ough smo othing (as descr ibed in Qualit y-Based S moothing (p.827)). 6.3.11.1. Recogniz ed ANSY S 5.4 and 5.5 D atasets ANSY S Fluen t can imp ort mesh files fr om ANSY S 5.4 and 5.5 ( .cdb files), retaining or iginal b oundar y names .The f ollowing ANSY S file da tasets ar e recogniz ed b y the ANSY S Fluen t mesh imp ort utilit y: •NBL OCK node blo ck da ta •EBL OCK elemen t blo ck da ta •CMBL OCK elemen t/no de gr ouping 729Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Mesh S ourcesThe elemen ts must b e STIF63 linear shell elemen ts. In addition, if elemen t da ta without an e xplicit elemen t ID is used , the filt er assumes sequen tial numb ering of the elemen ts when cr eating the z ones . 6.3.12. CFX F iles You c an imp ort the meshes fr om 3D CFX files , such as definition ( .def ) and r esult (.res ) files in to ANSY S Fluen t, using the File/Imp ort/CFX ribbon tab it em, as descr ibed in CFX F iles (p.604).The fe2ram utilit y is used as the imp ort filt er, which c an b e used as a stand-alone pr ogram t o obtain an ANSY S Fluen t mesh file . See Using the f e2ram F ilter to Convert Files (p.731) for inf ormation ab out fe2ram . Imp ortant Note tha t you ha ve the abilit y to imp ort only the mesh fr om a CFX file , and not an y results or da ta. When imp orting a mesh fr om a CFX definition or r esults file , selec t whether y ou w ant the ANSY S Fluen t zones t o be created fr om the ph ysics da ta objec ts or the pr imitiv e mesh r egion objec ts.The former option is the default and is c alled “Zoning b y CCL” and the la tter option is c alled “Zoning b y Group ”.This will allo w you t o cho ose the t ype of mesh t opology you w ould lik e to pr eser ve when imp orting the file: •If you w ant zones t o be created fr om the ph ysics da ta objec ts, enable Create Zones fr om C CL P hysics Data in the Selec t File dialo g box. •If you w ant zones t o be created fr om the pr imitiv e mesh r egion objec ts, disable Create Zones fr om C CL Physics D ata in the Selec t File dialo g box.This will r esult in the gr oup z oning . Imp ortant The pr imitiv e mesh t opology ma y contain additional r egions tha t do not app ear in the physics definition. The default imp ort metho d is the Create Zones fr om C CL P hysics D ata metho d.This metho d will not imp ort CFX sub domain r egions , however, the z oning b y gr oup metho d can imp ort sub domain regions . The 3D elemen t set c orresponding t o zones/domains pr esen t in these files ar e imp orted as c ell z ones in ANSY S Fluen t.They ma y contain t etrahedr al, pyramidal, wedge , and he xahedr al elemen ts.The boundar y zones in these files ar e a gr oup of fac es with a b oundar y condition name/t ype and ar e im- ported as fac e zones with the b oundar y condition name/t ype retained in ANSY S Fluen t.The f ollowing boundar y condition t ypes ar e retained: •inlet •outlet •symmetr y •interface •wall Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 730Reading and M anipula ting M eshesThe b oundar ies of t ype Interface ma y be conformal or non-c onformal. If the y are non-c onformal, they are retained . However, conformal in terfaces c ontain c oinciden t no des tha t are mer ged and changed to type Interior . For some c ases , for the mer ge t o work correctly, the mer ge t oler ance ma y need to be adjust ed. Alternatively, the Fuse F ace Zones D ialog Box (p.3829 ) in ANSY S Fluen t can b e used t o mer ge the c onformal in terfaces. For details , see Fusing F ace Zones (p.809). 6.3.13. Using the f e2ram F ilter to Convert Files The fe2ram filter can b e used t o manually c onvert files of c ertain f ormats in to ANSY S Fluen t mesh files , which c an then b e read in to ANSY S Fluen t.To use the fe2ram filter, enter the f ollowing a t a command pr ompt in a t erminal or c ommand windo w: utility fe2ram [dimension ] format [zoning ] input_file output_file Note The it ems enclosed in squar e br ackets ar e optional. Do not t ype the squar e br ackets. •dimension indic ates the dimension of the da taset. Replac e dimension with -d2 to indic ate tha t the mesh is two dimensional. For a 3D mesh, do not en ter an y value f or dimension , because 3D is the default. •format indic ates the f ormat of the file y ou w ant to convert. For e xample , replac e format with -tANSYS for a Mechanic al APDL file ,-tIDEAS for an I-deas file ,-tNASTRAN for a NASTR AN file , and so on. To pr int a list of the f ormats which fe2ram can c onvert, type utility fe2ram -cl -help . Note fe2ram do es not supp ort VRML 2.0 or la ter. •zoning indic ates ho w zones w ere iden tified in the or iginal f ormat. Replac e zoning by -zID for a mesh tha t was zoned b y pr operty IDs , or -zNONE to ignor e all z one gr oupings . For a mesh z oned b y gr oup , do not enter an ything f or zoning , because z oning b y gr oups is the default. •input_file is the name of the or iginal file .output_file is the name of the file t o which y ou w ant to wr ite the converted mesh inf ormation. For e xample , if y ou w anted t o convert the 2D I-deas v olume mesh file sample.unv to an output file c alled sample.grd , you will en ter the f ollowing c ommand: utility fe2ram -d2 -tIDEAS sample.unv sample.grd 6.3.14. Remo ving H anging N odes/E dges As not ed in Mesh Topologies (p.703), ANSY S Fluen t can acc ept meshes tha t contain hanging no des or hanging edges . However, the cr eation of in terior w alls c an yield an er ror if hanging no des/edges ar e located on the z one tha t is tur ned in to an in terior w all.This pr oblem c an o ccur in the f ollowing c ases: •If you r ead a mesh file tha t has an in terior (or t wo-sided) w all b oundar y condition setup , but the shado w wall has not b een cr eated y et. 731Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Mesh S ources•If you tur n an in terior sur face into a w all. •If you slit an in terior sur face (for e xample , turn it in to a non-c onformal in terface). Such er ror-pr oducing hanging no des / edges ma y be pr esen t in he xcore or C utCell meshes , for e xample . You c an r emo ve the hanging no des/edges b y converting the asso ciated c ells t o polyhedr a. Each c ell that is c onverted will r etain the same o verall dimensions , but the numb er of fac es asso ciated with the cell will incr ease .You ha ve the option of r eading the mesh in the meshing mo de of F luen t and then writing it with the Write As Polyhedr a option enabled; alternatively, you c ould r ead it in the solution mode of F luen t and use the mesh/polyhedra/convert-hanging-nodes text command . 6.3.14.1. Limitations Meshes with p olyhedr a ha ve the f ollowing limita tions: •The following mesh manipula tion t ools ar e not a vailable on p olyhedr al meshes: –extrude-face-zone under the modify-zone option –skewness smo othing –swapping (will not aff ect polyhedr al cells) •The p olyhedr al cells tha t result fr om the c onversion ar e not eligible f or adaption with the default hanging node metho d, though the y can b e refined with the p olyhedr al unstr uctured mesh adaption (PUMA) metho d. For mor e inf ormation ab out adaption, see Adapting the M esh (p.2705 ). •The p olyhedr al cells tha t result fr om this c onversion ha ve the f ollowing limita tions with r egar d to the update metho ds a vailable f or d ynamic mesh pr oblems: –When applying d ynamic la yering t o a c ell z one , you c annot ha ve polyhedr al cells adjac ent to the mo ving face zone . –None of the r emeshing metho ds e xcept f or C utCell z one r emeshing will mo dify p olyhedr al cells. Note tha t smo othing is allo wed f or p olyhedr al cells, and diffusion-based smo othing is r ecommended over spr ing-based smo othing (see Diffusion-B ased S moothing (p.1269 ) for details). The linear ly elastic solid smo othing metho d is not c ompa tible with p olyhedr al cells. 6.3.15. Fluen t/UNS and R AMP ANT C ase F iles If you ha ve a F luen t/UNS 3 or 4 c ase file or a R AMP ANT 2, 3, or 4 c ase file and y ou w ant to run an ANSY S Fluen t simula tion using the same mesh, you c an r ead it in to ANSY S Fluen t using the File/Read/C ase... ribbon tab it em, as descr ibed in Reading F luen t/UNS and R AMP ANT C ase and D ata Files (p.593). 6.3.16. FLUENT 4 C ase F iles If you ha ve a FL UENT 4 c ase file and y ou w ant to run an ANSY S Fluen t simula tion using the same mesh, imp ort it in to ANSY S Fluen t using the File/Imp ort/FL UENT 4 C ase F ile... ribbon tab it em, as descr ibed Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 732Reading and M anipula ting M eshesin Fluen t 4 C ase F iles (p.610). ANSY S Fluen t will r ead mesh inf ormation and z one t ypes fr om the FL UENT 4 case file . Imp ortant FLUENT 4 ma y interpret some pr essur e boundar ies diff erently fr om the cur rent release of ANSY S Fluen t. Check the c onversion inf ormation pr inted out b y ANSY S Fluen t to see if y ou need t o mo dify an y boundar y types. To manually c onvert an input file in FL UENT 4 f ormat to an output file in the cur rent ANSY S Flu- ent format, enter the f ollowing c ommand: utility fl42seg input_filename output_filename After the output file has b een wr itten, you c an r ead it in to ANSY S Fluen t using the File/Read/C ase... ribbon tab it em, as descr ibed in Reading M esh F iles (p.586). 6.3.17. ANSY S FIDAP N eutr al Files If you ha ve an ANSY S FIDAP N eutr al file and y ou w ant to run an ANSY S Fluen t simula tion using the same mesh, imp ort it using the r ibbon it em, as descr ibed in ANSY S FIDAP N eutr al Files (p.606). ANSY S Fluen t will r ead mesh inf ormation and z one t ypes fr om the ANSY S FIDAP file . To manually c onvert an input file in ANSY S FIDAP f ormat to an output file in ANSY S Fluen t utility fe2ram [ dimension ] -tFIDAP7 input_file output_file The it em in squar e br ackets is optional. Do not t ype the squar e br ackets. For a 2D file , replac e dimension with -d2 . For a 3D file , do not en ter an ything f or dimension , because 3D is the default. After the output file has b een wr itten, read it in to ANSY S Fluen t using the File/Read/C ase... ribbon tab it em, as descr ibed in Reading M esh F iles (p.586). 6.3.18. Reading M ultiple M esh/C ase/D ata F iles There ma y be some c ases in which y ou will need t o read multiple mesh files (sub domains) t o form your c omputa tional domain. •To solv e on a multiblo ck mesh, gener ate each blo ck of the mesh in the mesh gener ator and sa ve it t o a separ ate mesh file . •For v ery complic ated geometr ies, it ma y be mor e efficien t to sa ve the mesh f or each par t as a separ ate mesh file . The mesh no de lo cations need not b e iden tical at the b oundar ies wher e two separ ate meshes meet. ANSY S Fluen t can handle non-c onformal mesh in terfaces. See Non-C onformal M eshes (p.741) for details about non-c onformal mesh b oundar ies. There ar e thr ee w ays of r eading multiple mesh files in ANSY S Fluen t: •Read multiple mesh files in to the solution mo de of F luen t. •Read multiple mesh files in to the meshing mo de of F luen t. 733Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Mesh S ources•Use tmerge to manipula te the individual files and mer ge them in to a single file tha t can then b e read in to Fluen t. 6.3.18.1. Reading Multiple Mesh F iles via the S olution Mo de of F luent The solution mo de of F luen t allo ws you t o handle mor e than one mesh a t a time within the same solv er settings .This c apabilit y of handling multiple meshes sa ves time , sinc e you c an dir ectly r ead in the diff erent mesh files and star t setting up the solution, without ha ving t o swit ch o ver fr om meshing mode or emplo y another t ool such as tmerge . The st eps t o tak e when r eading mor e than one mesh file ar e: 1.Read in y our first mesh file . File → Read → Mesh... In The S elec t File D ialog Box (p.569) (Figur e 6.24: The S elec t File D ialog Box (p.734)), selec t the mesh file and click OK. Figur e 6.24: The S elec t File D ialo g Box Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 734Reading and M anipula ting M eshes2.Read in y our sec ond mesh file and app end it t o the first mesh selec ted in the first st ep. Domain → Zones → Append → Append C ase F ile... In The S elec t File D ialog Box (p.569), selec t the sec ond mesh file and click OK. 3.(optional). Displa y your meshes using the Mesh D ispla y dialo g box. Setup → Gener al → Displa y... You will find tha t the sec ond mesh is app ended t o the first. ANSY S Fluen t also allo ws you t o app end the da ta on the mesh. To do tha t, follow the pr ocedur e above. For the sec ond st ep, use the f ollowing r ibbon tab it em: Domain → Zones → Append → Append C ase & D ata F iles ... Selec t the c ase file in The S elec t File D ialog Box (p.569) (Figur e 6.24: The S elec t File D ialog Box (p.734)), and click OK. Both the c ase and da ta files will b e app ended . Imp ortant Review y our c ase setup af ter app ending multiple mesh and/or da ta files b efore pr oceeding with the c alcula tion. 6.3.18.2. Reading Multiple Mesh F iles via the Meshing Mo de of F luent 1.Gener ate the mesh f or the whole domain in the mesh gener ator, and sa ve each c ell z one (or blo ck or part) to a separ ate mesh file f or F luen t. Imp ortant If one (or mor e) of the meshes y ou w ant to imp ort is str uctured (f or e xample , a FL UENT 4 mesh file), first c onvert it t o ANSY S Fluen t format using the fl42seg filter descr ibed in FLUENT 4 C ase F iles (p.732). 2.In the meshing mo de of F luen t, combine the meshes in to one mesh file . a.Read all of the mesh files . As the mesh files ar e read, the y will b e aut oma tically mer ged in to a single mesh. b.Save the mer ged mesh file . See the F luen t Meshing sec tion of the U ser’s Guide f or inf ormation ab out r eading and wr iting files in meshing mo de. 3.Switch o ver to the solution mo de of F luen t or r ead the c ombined mesh file in to a new session using the File/Read/M esh... ribbon tab it em. For a c onformal mesh, if y ou do not w ant a b oundar y between the adjac ent cell z ones , use the Fuse Face Zones dialo g box to fuse the o verlapping b oundar ies. For details , see Fusing F ace Zones (p.809). 735Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Mesh S ourcesThe ma tching fac es will b e mo ved t o a new z one with a b oundar y type of interior and the or iginal zone(s) will b e disc arded . Imp ortant If you ar e planning t o use sliding meshes , or if y ou ha ve non-c onformal b oundar ies b etween adjac ent cell z ones , do not c ombine the o verlapping z ones . Inst ead, change the t ype of the t wo overlapping z ones t o interface (as descr ibed in Non-C onformal M eshes (p.741)). 6.3.18.3. Reading Multiple Mesh F iles via tmer ge 1.Gener ate the mesh f or the whole domain in the mesh gener ator, and sa ve each c ell z one (or blo ck or part) to a separ ate mesh file f or ANSY S Fluen t. Imp ortant If one (or mor e) of the meshes y ou w ant to imp ort is str uctured (f or e xample , a FL UENT 4 mesh file), first c onvert it t o ANSY S Fluen t format using the fl42seg filter descr ibed in FLUENT 4 C ase F iles (p.732). 2.Before launching F luen t, use the tmerge filter to combine the meshes in to one mesh file .The tmerge metho d allo ws you t o rotate, scale, and/or tr ansla te the meshes b efore the y are mer ged . Note tha t the tmerge filter allo ws you t o mer ge lar ge meshes with v ery low memor y requir emen t. a.For 3D pr oblems , type utility tmerge -3d . For 2D pr oblems , type utility tmerge -2d . b.When pr ompt ed, specify the names of the input files (the separ ate mesh files) and the name of the output file in which t o sa ve the c omplet e mesh. Be sur e to include the .msh extension. c.For each input file , specify sc aling fac tors, transla tion distanc es, and r otation inf ormation. For inf ormation ab out the v arious options a vailable when using tmerge , type utility tmerge -h. 3.Read the c ombined mesh file in to the solution mo de of F luen t in the usual manner (using the File/Read/M esh... ribbon tab it em). For a c onformal mesh, if y ou do not w ant a b oundar y between the adjac ent cell z ones , use the Fuse Face Zones dialo g box to fuse the o verlapping b oundar ies. For details , see Fusing F ace Zones (p.809). The ma tching fac es will b e mo ved t o a new z one with a b oundar y type of interior and the or iginal zone(s) will b e disc arded . Imp ortant If you ar e planning t o use sliding meshes , or if y ou ha ve non-c onformal b oundar ies b etween adjac ent cell z ones , do not c ombine the o verlapping z ones . Inst ead, change the t ype of the t wo overlapping z ones t o interface (as descr ibed in Non-C onformal M eshes (p.741)). In this e xample , scaling , transla tion, or r otation is not r equest ed. Hence you c an simplify the inputs to the f ollowing: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 736Reading and M anipula ting M eshes user@mymachine:> utility tmerge -2d Starting /ansys_inc/v195/fluent/fluent19.5.0/utility/tmerge/lnamd64/tmerge_2d Append 2D grid files. tmerge2D ANSYS Inc, stream Enter name of grid file (ENTER to continue) : my1.msh x,y scaling factor, eg. 1 1 : 1 1 x,y translation, eg. 0 1 : 0 0 rotation angle (deg), eg. 45 : 0 Enter name of grid file (ENTER to continue) : my2.msh x,y scaling factor, eg. 1 1 : 1 1 x,y translation, eg. 0 1 : 0 0 rotation angle (deg), eg. 45 : 0 Enter name of grid file (ENTER to continue) : {Enter} Enter name of output file : final.msh Reading... node zone: id 1, ib 1, ie 1677, typ 1 node zone: id 2, ib 1678, ie 2169, typ 2 . . . done. Writing... 492 nodes, id 1, ib 1678, ie 2169, type 2. 1677 nodes, id 2, ib 1, ie 1677, type 1. . . . done. Appending done. 6.3.19. Reading S urface M esh F iles Surface meshes ar e used as back ground meshes f or geometr y-based adaption. Perform the f ollowing steps t o read the sur face mesh file in to ANSY S Fluen t: 1.Open the Geometr y Based A daption dialo g box. Domain → Adapt → More → Geometr y... 2.Enable the Rec onstr uct Geometr y option. 3.Click the Surface M eshes ... butt on t o op en the Surface M eshes dialo g box (Figur e 6.25: The Sur face Meshes D ialog Box (p.738)). 4.In the Surface Meshes D ialog Box (p.3929 ), click Read ... and selec t the sur face mesh file using The S elec t File D ialog Box (p.569). Specify the units the mesh w as cr eated in (default is met ers). Note tha t you c an also displa y and delet e the sur faces using Figur e 6.25: The Sur face M eshes D ialog Box (p.738). 737Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Mesh S ourcesFigur e 6.25: The S urface M eshes D ialo g Box 6.4. Ref erenc e Frames You c an cr eate multiple lo cal reference frames f or use in setting up ANSY S Fluen t cases . The r eference frames f eature allo ws you t o cr eate lo cal coordina te sy stems with a giv en p osition and orientation, either with or without motion. Without lo cal reference frames , you w ould ha ve to sp ecify things such as sur faces based on the global r eference frame/c oordina te sy stem. 6.4.1. Creating and U sing Ref erenc e Frames To cr eate a r eference frame: 1.Open the Referenc e Frame dialo g box by right-click ing Referenc e Frames in the outline view and selec ting New.... Setup → Referenc e Frames New... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 738Reading and M anipula ting M eshesFigur e 6.26: The Ref erenc e Frame D ialo g Box 2.Enter a Name for the r eference frame . 3.Specify ho w you w ant to define the r eference frame . •User D efined allo ws you t o complet ely sp ecify the details of wher e the r eference frame is lo cated and oriented and ho w it mo ves. •Track b y Zone allo ws you t o "a ttach" a r eference frame t o a c ell z one .You c an still sp ecify wher e the reference frame is lo cated and ho w it is or iented, but y ou c annot sp ecify an y motion. If the z one it is tracking mo ves, so do es the r eference frame . 4.Specify either the Parent reference frame (when y ou selec t User D efined) or the Zone tha t the r eference frame will tr ack (when y ou selec t Track b y Zone . 5.(Optional, User D efined only) enable Motion and sp ecify the additional settings tha t app ear in the Motion tab. 739Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Reference FramesFigur e 6.27: The M otion Tab of the Ref erenc e Frame D ialo g Box •Linear Velocity is the linear v elocity with r espect to the par ent reference frame or ientation. •Rota tional Velocity is the r otational v elocity with r espect to the par ent reference frame or ientation. 6.Specify the Origin of y our r eference frame . 7.Specify the or ientation of the first axis of y our r eference frame in the Axis-1 Or ientation group b ox. Selec t which axis y ou ar e sp ecifying using b y selec ting either the X,Y, or Z radio butt on. You c an either sp ecify the or ientation b y pr oviding a p oint or a dir ection. 8.(Optional) S pecify the or ientation of the sec ond axis of y our r eference frame . By default , Fluen t aut oma t- ically pr ovides an or ientation f or the sec ond axis , but y ou c an sp ecify it manually b y disabling Automa tic and pr oviding y our o wn inputs . 9.Click OK to create the r eference frame . The Current State field sho ws you the cur rent origin and ax es dir ections of the r eference frame with respect to the global r eference frame . Using R efer enc e Frames You c an use an y local reference frame when defining p oint sur faces and pr ofiles . Just selec t the desir ed reference frame fr om the Referenc e Frame drop-do wn in the Point Surface or Profile dialo g boxes. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 740Reading and M anipula ting M eshesFigur e 6.28: Point Surface Creation on L ocal Ref erenc e Frame Figur e 6.29: Profile D efinition on L ocal Ref erenc e Frame 6.5. Non-C onformal M eshes In ANSY S Fluen t it is p ossible t o use a mesh tha t has non-c onformal in terfaces, tha t is, boundar ies between c ell z ones in which the mesh no de lo cations ar e not iden tical. Such non-c onformal in terfaces permit the c ell z ones t o be easily c onnec ted t o each other b y passing flux es fr om one mesh t o another . The pr inciple r equir emen t is tha t the b oundar y zones tha t mak e up the non-c onformal in terface must overlap either par tially or fully . (This r equir emen t do es not apply t o non-c onformal p eriodic b oundar ies.) 6.5.1. Non-C onformal M esh C alcula tions 6.5.2. Non-C onformal In terface Algor ithm 6.5.3. Requir emen ts and Limita tions of N on-C onformal M eshes 6.5.4. Using a N on-C onformal M esh in ANSY S Fluen t 741Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Non-C onformal M eshes6.5.1. Non-C onformal M esh C alcula tions To comput e the flux acr oss the non-c onformal b oundar y, ANSY S Fluen t must first c omput e the in ter- section b etween the in terface zones tha t mak e up the b oundar y. In the c ase of a solid-t o-solid z one interface of the same ma terial or a fluid-t o-fluid z one in terface, the r esulting in tersec tion pr oduces an interior z one wher e the t wo in terface zones o verlap (see Figur e 6.30: Complet ely O verlapping M esh Interface In tersec tion (p.742)). In the c ase of a solid-t o-solid z one in terface of diff erent ma terials or a fluid-t o-solid z one in terface, the b oundar y is tr eated as a c oupled w all (see The C oupled Wall Op- tion (p.747)). Figur e 6.30: Complet ely O verlapping M esh In terface In tersec tion If one of the in terface zones e xtends b eyond the other ( Figur e 6.31: Partially O verlapping M esh In terface Intersec tion (p.742)), by default ANSY S Fluen t will cr eate additional w all z ones f or the p ortion(s) of the boundar y wher e the t wo in terface zones do not o verlap; these ar e referred t o as "non-o verlapping zones", and c an b e changed t o be other b oundar y conditions t ypes a t your discr etion. Figur e 6.31: Partially O verlapping M esh In terface In tersec tion Fluxes acr oss the mesh in terface ar e comput ed using the fac es resulting fr om the in tersec tion of the two in terface zones , not fr om the in terface zone fac es. In the e xample sho wn in Figur e 6.32: Two-Dimensional N on-C onformal M esh In terface (p.743), the in- terface zones ar e comp osed of fac es A-B and B-C, and fac es D-E and E-F . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 742Reading and M anipula ting M eshesFigur e 6.32: Two-D imensional N on-C onformal M esh In terface The in tersec tion of these z ones pr oduces the fac es a-d , d-b , b-e , and e-c . Faces pr oduced in the r egion wher e the t wo cell z ones o verlap (d-b , b-e , and e-c) ar e gr oup ed t o form an in terior or c oupled w all zone (dep ending on the t ypes of the adjac ent cell z ones), while the r emaining fac e (a-d) f orms a w all zone . To comput e the flux acr oss the in terface in to cell IV , face D-E is ignor ed and inst ead fac es d-b and b- e ar e used t o br ing inf ormation in to cell IV fr om c ells I and III. While the pr evious discussion descr ibed the default tr eatmen t of a non-c onformal in terface, ther e ar e several options y ou c an enable a t the in terface in or der t o revise the tr eatmen t of the flux es and/or reduc e the memor y usage and pr ocessing time: •periodic b oundar y condition •periodic r epeats •coupled w all •matching •mapp ed •static These non-c onformal in terface options ar e descr ibed in the f ollowing sec tions . 6.5.1.1. The P eriodic B oundar y Condition Option 6.5.1.2. The P eriodic R epeats Option 6.5.1.3. The C oupled Wall Option 6.5.1.4. Matching Option 743Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Non-C onformal M eshes6.5.1.5. The M app ed Option 6.5.1.6. The S tatic Option 6.5.1.7. Interface Zones A utoma tic N aming C onventions 6.5.1.1. The P erio dic B oundar y Condition O ption Non-c onformal in terfaces c an b e used t o implemen t a p eriodic b oundar y condition lik e tha t descr ibed for c onformal p eriodic b oundar ies (see Periodic B oundar y Conditions (p.999)).The ad vantage of using a mesh in terface is tha t, unlik e the standar d periodic b oundar y condition, the no des of the t wo zones do not ha ve to ma tch one-f or-one . The in terface zones tha t utiliz e the p eriodic b oundar y condition option ( Figur e 6.33: Non-C onformal Periodic B oundar y Condition ( Transla tional) (p.744) and Figur e 6.34: Non-C onformal P eriodic B oundar y Condition (R otational) (p.745)) are coupled in the manner descr ibed in the pr evious sec tion, except that the z ones do not o verlap (tha t is, the z ones ar e not spa tially c oinciden t at an y point). In or der to gener ate the new fac es tha t will b e used t o comput e the flux es acr oss the in terface, the no des of the first z one ar e either tr ansla ted or r otated (ab out a giv en axis) on to the other z one .The dis- tanc e/angle tha t the no des ar e transla ted/r otated is c alled the “periodic off set”.The new fac es will be defined b etween all of the c ombined no des, and then applied t o each of the or iginal z ones . Figur e 6.33: Non-C onformal P eriodic B oundar y Condition ( Transla tional) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 744Reading and M anipula ting M eshesFigur e 6.34: Non-C onformal P eriodic B oundar y Condition (Rota tional) 6.5.1.2. The P erio dic R epeats O ption The p eriodic r epeats option is appr opriate when each of the in terface zones is adjac ent to a non- conformal p eriodic in terface or a pair of c onformal p eriodic z ones (see Figur e 6.35: Transla tional N on- Conformal In terface with the P eriodic R epeats Option (p.746) and Figur e 6.36: Rotational N on-C onformal Interface with the P eriodic R epeats Option (p.747)).The p eriodic r epeats option tak es in to acc oun t the r epeating na ture of the flo w solutions in the t wo cell z ones in the f ollowing manner .Wherever the in terface zones o verlap (tha t is, wher ever in terface zone 1 and 2 ar e spa tially c oinciden t), the fluxes on either side of the in terface ar e coupled in the usual w ay.The p ortion of in terface zone 1 that do es not o verlap is c oupled t o the non-o verlapping p ortion of in terface zone 2, by transla ting or rotating the flux es b y the p eriodic off set. This is similar t o the tr eatmen t of non-c onformal p eriodic boundar y conditions .The p eriodic r epeats option is t ypic ally used in c onjunc tion with the sliding mesh mo del when simula ting the in terface between a r otor and sta tor. Note The p eriodic r epeats option is not supp orted if the in terface zone is adjac ent to a solid zone . 745Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Non-C onformal M eshesFigur e 6.35: Transla tional N on-C onformal In terface with the P eriodic Rep eats Option Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 746Reading and M anipula ting M eshesFigur e 6.36: Rota tional N on-C onformal In terface with the P eriodic Rep eats Option 6.5.1.3. The C oupled Wall O ption As descr ibed pr eviously , the t ypic al func tion of non-c onformal in terfaces is t o couple fluid z ones , so as to permit fluid flo w to pass fr om one mesh in terface to the other . Another a vailable option is t o create a c oupled w all b oundar y at the in terface. In such a c ase, fluid flo w w ould not pass acr oss the interface, as the in terface is ac ting as a w all z one . Coupled w all hea t transf er, on the other hand , would b e permitt ed. Such tr eatmen t is applied b y default in the c ase of a solid-t o-solid z one in terface of diff erent ma terials or a fluid-t o-solid z one in terface. For fluid-t o-fluid z one in terfaces, you must enable the Coupled Wall option t o ha ve such tr eatmen t; for e xample , you c an mo del a thin w all or baffle separ ating the t wo fluid z ones .Figur e 6.37: Non-C onformal C oupled Wall In terfaces (p.748) illus- trates c oupled w alls with b oth solid and fluid z ones . Note tha t coupled w alls c an also mak e use of the p eriodic r epeats option. That is, both options c an be invoked simultaneously . For details see Using a N on-C onformal M esh in ANSY S Fluen t (p.756). 747Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Non-C onformal M eshesFigur e 6.37: Non-C onformal C oupled Wall In terfaces 6.5.1.4. Matching O ption When t wo in terface zones do not ma tch w ell (which c ould r esult fr om diff erent mesh t opologies , geometr ic misalignmen t, or the e xistence of lar ge gaps), wall z ones will b e created on the in terface. If, in such c ases , you w ant to ha ve only in ternal z ones gener ated on the in terface (tha t is, interior or wall / shado w pairs), it is b est t o use a ma tching in terface. If the in terface zones ar e complet ely overlapping (see Figur e 6.30: Complet ely O verlapping M esh In terface In tersec tion (p.742)) as opp osed to par tially o verlapping (see Figur e 6.31: Partially O verlapping M esh In terface In tersec tion (p.742)) and so no w all z ones ar e expected t o be created on the mesh in terface, it is r ecommended tha t you selec t the Matching option. Note The Matching option is also c ompa tible with the p eriodic b oundar y condition option. Figur e 6.38: Matching N on-C onformal Wall In terfaces (p.749) below sho ws two in terface zones tha t do not ma tch up w ell in the c enter -- the in terface zone on the r ight has an in verted spik e. Even with such a lar ge misma tch, the Matching option still enables y ou t o cr eate an in terface with only the interior z one . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 748Reading and M anipula ting M eshesFigur e 6.38: Matching N on-C onformal Wall In terfaces When the Matching option is selec ted, ANSY S Fluen t checks if one in terface zone sits on t op of the other and displa ys messages if ther e is an o verlap of c ell z ones tha t are connec ted thr ough a mesh interface (ther efore mak ing the in terface invalid f or use). Since the se verity of z one o verlap is diff erent for ma tching in terfaces and non-ma tching in terfaces, ANSY S Fluen t displa ys diff erent messages ac- cordingly . For e xample , for non-ma tching in terfaces: Info: Interface zones overlap for mesh interface (interface-name). This could adversely affect your solution. Likewise , for ma tching in terfaces: Warning: Interface zone overlaps for mesh interface (interface-name). This could generate left-handed faces on the interface and make it invalid for use. 6.5.1.5. The M app ed O ption The Mapp ed option is an alt ernative appr oach f or mo deling c oupled w alls b etween z ones .This ap- proach pr ovides b etter handling f or in terface zones tha t penetr ate each other or ha ve gaps b etween them. The Mapp ed option is useful in situa tions wher e using the standar d non-c onformal in terface 749Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Non-C onformal M eshesformula tions c auses the simula tion t o fail (as ma y occur when ther e is in terface penetr ation or gaps between in terfaces, causing the cr eation of lef t-handed fac es a t the in terface). Figur e 6.39: Non-C onformal M app ed In terface with a G ap and P enetr ation Figur e 6.39: Non-C onformal M app ed In terface with a G ap and P enetr ation (p.750) sho ws signific ant penetr ation b etween the t wo in terface zones and lar ge gap .The mapp ed option allo ws you t o cr eate a coupled w all e ven with the lar ge amoun t of p enetr ation and gap sho wn in this image . The Mapp ed option only w orks in c onjunc tion with the Coupled Wall option. Enabling the Mapp ed automa tically enables Coupled Wall. You c an use the Interface Options D ialog Box (p.3838 ) to mo dify the global settings f or the mapp ed interfaces, as w ell as t o convert existing mesh in terfaces (either all of them or just those tha t ha ve penetr ating z ones) t o use the Mapp ed option. You c an c onfir m tha t you cr eated go od qualit y mapp ed in terfaces b y performing a mesh check. If you ha ve mapp ed in terfaces tha t did not pass the qualit y check, Fluen t will suggest tha t you use the text command define/mesh-interface/improve-quality , which allo ws you t o incr ease the interface toler ance to impr ove the qualit y of the mapp ed in terfaces. In pr oblems set up in v ersion 19.2 or ear lier, wher e you ha ve a solid z one adjac ent to a fluid z one (conjuga te hea t transf er) with a mapp ed mesh in terface between them, it is r ecommended y ou swit ch from the e xplicit c oupling metho d to the implicit metho d using the t ext command /define/mod- els/cht/implicit-coupling? .The implicit metho d pr oduces b etter convergenc e behavior compar ed t o the e xplicit metho d for these fluid-solid pairs . Note tha t the implicit metho d is the no w the default. Note the f ollowing limita tions when using the Mapp ed option: •The Mapp ed option c an only b e applied if a t least one side of the in terface consists of only solid z ones . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 750Reading and M anipula ting M eshes•The Mapp ed option is not c ompa tible with shell c onduc tion. •Thermal c oupling c alcula tions will not b e performed a t mapp ed in terfaces for the E uler ian multiphase model. •No other in terface options b esides Coupled Wall are allo wed with the Mapp ed option. •For the S2S mo del, the Face to Face basis f or the view fac tors is not c ompa tible with mapp ed in terfaces for p olyhedr al meshes . •Mapp ed in terfaces ar e not supp orted with the densit y-based solv er. •Mapp ed in terfaces ar e not supp orted with the Lagr angian discr ete phase mo del. •Mapp ed in terfaces ar e not supp orted with mo ving / def orming meshes . 6.5.1.6. The Static O ption For a default mesh in terface or when the Coupled and/or Matching options ar e enabled , ANSY S Fluen t will aut oma tically cr eate zones tha t will b e needed if the in terface should change due t o motion (from mo ving r eference frames or sliding meshes) or def ormation. If you k now in ad vance tha t the interface zones will not b e mo ving or def orming r elative to each other a t the in terface, then (and only then) it is r ecommended tha t you enable the Static option. The Static option pr events the cr eation of such z ones , and thus r educ es the memor y usage and pr ocessing time (f or b oth the cr eation of the interface and the r unning of the c alcula tion). This r educ tion c an b e signific ant, esp ecially when ther e are man y zones on b oth sides of the in terface. Warning If the Static option is applied a t an in terface tha t do es end up under going r elative motion or def ormation, the r esults will b e inc orrect. Note tha t the Static option is not limit ed t o steady-sta te cases . 6.5.1.7. Interface Zones A utomatic N aming C onventions The f ollowing sub-sec tions descr ibe the aut oma tic naming c onventions f or each t ype of non-c onformal interface. Note tha t in these descr iptions: • is user sp ecified • is a v alue b etween 1 and m, wher e m is the numb er of z ones in in terface zone side 1 • is a v alue b etween 1 and n, wher e n is the numb er of z ones in in terface zone side 2 • is 1 or 2 6.5.1.7.1. Default (N o Options Enabled) 6.5.1.7.2. Periodic B oundar y Condition 6.5.1.7.3. Periodic R epeats 6.5.1.7.4. Coupled Wall 751Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Non-C onformal M eshes6.5.1.7.5. Matching 6.5.1.7.6. Mapp ed 6.5.1.7.7. Static 6.5.1.7.1. Default (N o O ptions E nabled) The aut oma tic naming c onvention f or the non-o verlapping z ones is as f ollows: - non-o verlapping . The aut oma tic naming c onvention f or in terface wall z one side 1 is as f ollows: - wall1 - - . The aut oma tic naming c onvention f or in terface wall z one side 2 is as f ollows: - wall1 - - - shado w. The aut oma tic naming c onvention f or in terface in terior z ones is as f ollows: - interior - - . 6.5.1.7.2. Perio dic B oundar y Condition The aut oma tic naming c onvention f or the non-o verlapping z ones is as f ollows: - non-o verlapping . The aut oma tic naming c onvention f or in terface in terior z ones is as f ollows: - periodic. 6.5.1.7.3. Perio dic R epeats The aut oma tic naming c onvention f or in terface in terior z ones is as f ollows: - periodic. 6.5.1.7.4. Coupled Wall The aut oma tic naming c onvention f or the non-o verlapping z ones is as f ollows: - non-o verlapping . The aut oma tic naming c onvention f or in terface wall z one side 1 is as f ollows: - wall1 - - . The aut oma tic naming c onvention f or in terface wall z one side 2 is as f ollows: - wall1 - - - shado w. For e xample , > define/mesh-interfaces/list List of Mesh Interfaces Interface Name: cw:01 Interface Options: Coupled Description Name ID Area Area Percentage --------------------------- ---------------------------- -------- ----------------- ----------------- Interface-Zone-1 a2 17 0.1707190424 Interface-Zone-1 a1 13 0.1707191467 Interface-Zone-2 b1 4 36.7499923706 Non-Overlapping-Zone-Side-2 b1-non-overlapping 53 36.4085540771 99.070915% Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 752Reading and M anipula ting M eshes Interface-Wall-Zone-1 cw:01-wall1-1-1 50 0.1706306934 99.948250% Interface-Wall-Zone-1 cw:01-wall1-2-1 49 0.1706308126 99.948257% Interface-Wall-Zone-2 cw:01-wall1-1-1-shadow 54 0.1706306934 0.464301% Interface-Wall-Zone-2 cw:01-wall1-2-1-shadow 55 0.1706308126 0.464302% 6.5.1.7.5. Matching The aut oma tic naming c onvention f or in terface in terior z ones is as f ollows: - interior - - . 6.5.1.7.6. Mapp ed The aut oma tic naming c onvention f or the non-o verlapping z ones is as f ollows: - non-o verlapping . The aut oma tic naming c onvention f or in terface wall z ones is as f ollows: - wall - - . For e xample , > define/mesh-interfaces/list List of Mesh Interfaces Interface Name: map:01 Interface Options: Mapped Description Name ID Area Area Percentage --------------------------- ---------------------------- -------- ----------------- ----------------- Interface-Zone-1 a2 17 0.1707190424 Interface-Zone-1 a1 13 0.1707191467 Interface-Zone-2 b1 4 36.7499923706 Non-Overlapping-Zone-Side-2 b1-non-overlapping 32 36.4085540771 99.070915% Interface-Wall-Zone-1 map:01-wall1-a2 28 0.1707190424 100.000000% Interface-Wall-Zone-1 map:01-wall1-a1 27 0.1707191467 100.000000% Interface-Wall-Zone-2 map:01-wall2-b1 29 0.3414205313 0.929036% 6.5.1.7.7. Static The Static option do es not aff ect the naming c onventions of the z ones; tha t is, the z one names will be based en tirely on the other settings in the Interface Options group b ox. 6.5.2. Non-C onformal In terface Algor ithm In the cur rent version of ANSY S Fluen t, non-c onformal in terface calcula tions ar e handled using one of three appr oaches dep ending on the t ype of in terface.Coupled Wall interfaces ar e handled using in- terface boundar y metr ics and Mapp ed interfaces use a pr ojec tion appr oach. The in terface boundar y metr ics and pr ojec tion appr oach ar e both r obust algor ithms tha t avoid cr eating lef t-handed fac es and are par ticular ly useful when y ou ha ve comple x geometr ies. The r emaining t ypes of non-c onformal in terfaces ar e handled using a vir tual p olygon appr oach. The virtual p olygon appr oach st ores the ar ea v ector and c entroid of the p olygon fac es.This appr oach do es not in volve no de mo vemen t and c ells ar e not nec essar ily w ater-tigh t cells. Hence gr adien ts ar e corrected to tak e in to acc oun t the missing fac e ar ea. Note tha t in tr ansien t cases , the sta tionar y non-c onformal interfaces will b e aut oma tically pr eser ved b y ANSY S Fluen t dur ing mesh up date. 753Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Non-C onformal M eshesPrevious v ersions (16.0 and ear lier) of F luen t used the vir tual p olygon appr oach f or all non-c onformal interfaces.The in terface boundar y metr ics is a mor e robust appr oach f or cr eating c oupled w all in terfaces than the vir tual p olygon appr oach b ecause it a voids cr eating lef t-handed fac es. Older v ersions of F luen t (6.1 or ear lier) used a tr iangular fac e appr oach, which tr iangula ted the p olygon in tersec tion fac es and stored tr iangular fac es.This appr oach in volved no de mo vemen t and w ater-tigh t cells, and w as not as stable as the vir tual p olygon appr oach. Note tha t case files cr eated in r eleases pr ior t o 16.0 c an b e read and r un nor mally in the cur rent version of F luen t unless y ou r ecreate an y of the in terfaces. Recre- ated c oupled w all in terfaces will use in terface boundar y metr ics and all other r ecreated in terfaces will use the vir tual p olygon appr oach. It is p ossible tha t dist orted meshes ma y be pr oduced dur ing sliding mesh c alcula tions , gener ating lef t- handed fac es.You c annot obtain a flo w solution un til all of the fac es ar e “right handed ”, and so ANSY S Fluen t corrects the lef t-handedness of these fac es aut oma tically. In e xtreme c ases , the lef t-handed faces c annot b e fully c orrected and ar e delet ed aut oma tically, so tha t the solution do es not div erge. Left-handed c ells c an also b e created f or the geometr ies tha t contain shar p edges and c orners , which may aff ect the final solution. For such geometr ies, you should first separ ate the z ones and then cr eate the in terfaces separ ately t o get the b etter solution. The additional input of the angle/tr ansla tion v ector a t the angle/translation-vector prompt in the c onsole ma y be requir ed t o recreate fac e-periodic in terfaces. Also, with the cur rent mesh in terface algor ithm in par allel, ther e is no need f or enc apsula tion. 6.5.3. Requir emen ts and Limita tions of N on-C onformal M eshes This sec tion descr ibes the r equir emen ts and limita tions of non-c onformal meshes: •The mesh in terface can b e of an y shap e (including a non-planar sur face, in 3D), provided tha t the t wo in- terface boundar ies ar e based on the same geometr y. If ther e are shar p features (f or e xample , 90-degr ee angles) or cur vature in the mesh, it is esp ecially imp ortant tha t both sides of the in terface closely f ollow that feature. For e xample , consider the c ase of t wo concentric cir cles tha t define t wo fluid z ones with a cir cular , non-c onformal in terface between them, as sho wn in Figur e 6.40: A C ircular N on-C onformal In ter- face (p.755). Because the no de spacing on the in terface edge of the out er fluid z one is c oarse c om- pared t o the r adius of cur vature, the in terface do es not closely f ollow the f eature (in this c ase, the circular edge .) Imp ortant The maximum t oler ance between t wo in terfaces should not b e lar ger than their adjac ent cell siz e at tha t location That is no c ell should b e complet ely enclosed b etween t wo in ter- faces. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 754Reading and M anipula ting M eshesFigur e 6.40: A C ircular N on-C onformal In terface •If you cr eate a single mesh with multiple c ell z ones separ ated b y a non-c onformal b oundar y, you must b e sure tha t each c ell z one has a distinc t fac e zone on the non-c onformal b oundar y. The fac e zones f or two adjac ent cell z ones will ha ve the same p osition and shap e, but one will c or- respond t o one c ell z one and one t o the other . It is also p ossible t o cr eate a separ ate mesh file f or each of the c ell z ones , and then mer ge them as descr ibed in Reading M ultiple M esh/C ase/D ata Files (p.733). •All periodic z ones must b e correctly or iented (either r otational or tr ansla tional) b efore you cr eate the non- conformal in terface. •In or der f or the p eriodic b oundar y condition option or p eriodic r epeats option t o be valid, the edges of the sec ond in terface zone must b e off set fr om the c orresponding edges of the first in terface zone b y a unif orm amoun t (either a unif orm tr ansla tional displac emen t or a unif orm rotation angle). This is not tr ue for non-c onformal in terfaces in gener al. The p eriodic b oundar y condition option has the additional r equir emen t tha t the angle asso ciated with a r otationally p eriodic must b e able t o divide 360 without r emainder . •The p eriodic r epeats option r equir es tha t some p ortion of the t wo interface zones must o verlap (tha t is, be spa tially c oinciden t). •The p eriodic r epeats option r equir es tha t the non-o verlapping p ortions of the in terface zones must ha ve iden tical shap e and dimensions . If the in terface is par t of a sliding mesh, you must define the mesh motion such tha t this cr iterion is met a t all times . •Note tha t for 3D c ases , you c annot ha ve mor e than one pair of c onformal p eriodic z ones adjac ent to each of the in terface zones . •You must not ha ve a single non-c onformal in terface wher e par t of the in terface is made up of a c oupled two-sided w all, while another par t is not c oupled (tha t is, the nor mal in terface treatmen t). In such c ases , you must br eak the in terface up in to two interfaces: one tha t is a c oupled in terface, and the other tha t is a standar d fluid-fluid in terface. See Using a N on-C onformal M esh in ANSY S Fluen t (p.756) for inf ormation about cr eating c oupled in terfaces. 755Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Non-C onformal M eshes•For simula tions tha t involve the F luen t, Mechanic al, and M eshing applic ations , meshing pr oblems c an ar ise in instanc es wher e ther e are multiple r egions and c ontacts between them. In F luen t, a zone c an only e xist in a single c ontact region. The M echanic al and M eshing applic ations b oth use a diff erent appr oach c on- cerning c ontact regions when c ompar ed t o Fluen t. •Fluid z ones designa ted as 3D fan z ones c annot ha ve non-c onformal in terfaces. 6.5.4. Using a N on-C onformal M esh in ANSY S Fluen t If your multiple-z one mesh includes non-c onformal b oundar ies, check if the mesh meets all the r equir e- men ts (list ed in Requir emen ts and Limita tions of N on-C onformal M eshes (p.754)).This ensur es tha t ANSY S Fluen t can obtain a solution on the mesh. Then do the f ollowing: 1.Read the mesh in to ANSY S Fluen t. If you ha ve multiple mesh files tha t ha ve not y et b een mer ged , first follow the instr uctions in Reading M ultiple M esh/C ase/D ata Files (p.733) to mer ge them in to a single mesh. 2.For all of the z ones tha t mak e up the non-c onformal b oundar ies, change the t ype to interface (as descr ibed in Changing C ell and B oundar y Zone Types (p.837)). Setup → Boundar y Conditions 3.Open the Mesh In terfaces D ialog Box (p.3852 ) (Figur e 6.41: The M esh In terfaces D ialog Box (p.756)). Setup → Mesh In terfaces New... Figur e 6.41: The M esh In terfaces D ialo g Box 4.Create all of the mesh in terfaces tha t use the p eriodic or p eriodic r epeat option. This must b e done using the manual metho d, by click ing the Manual C reate... butt on and using the Create/Edit M esh In terfaces Dialog Box (p.3794 ). For details , see Manually C reating M esh In terfaces (p.762). 5.Create all of the mesh in terfaces tha t do not use the p eriodic or p eriodic r epeat option, using the aut oma tic metho d. As par t of this metho d, Fluen t will aut oma tically det ermine which of the selec ted in terface boundar y zones c an b e gr oup ed t ogether t o form the t wo sides of one or mor e mesh in terfaces. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 756Reading and M anipula ting M eshesTo use the aut oma tic metho d, perform the f ollowing st eps in the Mesh In terfaces dialo g box: a.Selec t all of the z ones in the selec tion list in the Unassigned In terface Zones group b ox.This list contains only those z ones tha t are not alr eady par t of an e xisting mesh in terface. Note tha t you ma y want to selec t only some of the z ones when y ou w ant the r esulting mesh in terfaces to ha ve diff erent name pr efixes or diff erent settings in the Auto Create Options dialo g box (as descr ibed in the st eps that follow); for e xample , you c ould selec t only the in terface zones fr om the fr ont half of a mo del, and then ha ve all of the r esulting mesh in terfaces named with the pr efix "fr ont". b.Enter the Interface Name P refix you w ant applied t o all of the r esulting in terfaces. c.(optional) C lick the Options… butt on in the Unassigned In terface Zones group b ox to op en the Auto Create Options D ialog Box (p.3785 ), and enable the settings tha t you w ant applied t o all of the resulting in terfaces. Figur e 6.42: The A uto Create Options D ialo g Box •You c an sp ecify tha t all of the r esulting in terfaces ar e created using One t o One P airing, so tha t a single z one is assigned t o each side of all of the mesh in terfaces. Using this option ma y decr ease your c omputa tional e xpense and help with tr oublesho oting la ter on, though it ma y pr oduce a lar ger numb er of mesh in terfaces for y ou t o manage . Note tha t you c an sp ecify the pr oximit y toler ance tha t ANSY S Fluen t uses t o det ermine which zones should b e gr oup ed t ogether as one-t o-one in terfaces.The pr oximit y toler ance is defined relative to the edge lengths in the in terface zones , and c an r ange fr om 0 to 1 (represen ting the minimum and maximum edge lengths , respectively). Examples of when y ou ma y need to adjust this setting fr om the default v alue of 0.5 include: when y ou ha ve multiple mesh interfaces tha t are close t o each other (in which c ase y ou ma y need a smaller t oler ance so that the z ones ar e not gr oup ed er roneously); and when y ou ha ve very small edges on an interface zone (in which c ase y ou ma y need a lar ger t oler ance so tha t the mesh in terface is iden tified). To revise the pr oximit y toler ance, use the f ollowing t ext command: define → mesh-interfaces → auto-options → proximity-tolerance •You c an sp ecify tha t the mapp ed option is applied t o all of the r esulting in terfaces for which a t least one side of the in terface consists of only solid z ones , by enabling the Mapp ed option. Note tha t the mapp ed option will b e applied r egar dless of the mesh qualit y, and the t oler ance used f or mapping will b e tha t specified in the Interface Options D ialog Box (p.3838 ). For mor e inf ormation about the mapp ed option, see The M app ed Option (p.749). •You c an sp ecify tha t all of the r esulting in terfaces use the Static option, if and only if y ou k now tha t the in terface zones will not b e mo ving or def orming r elative to each other a t the in terface.While 757Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Non-C onformal M eshesyou will ha ve the abilit y to enable the sta tic option af ter the in terfaces ar e created, doing so pr ior to creation a voids the cr eation of unnec essar y zones (and thus sa ves memor y usage and pr ocessing time , which c an b e signific ant when y ou ha ve selec ted man y Unassigned In terface Zones ). d.Click the Auto Create butt on in the Mesh In terfaces dialo g box to create the in terfaces.The r esulting interfaces will b e added t o the Mesh In terfaces list. Note tha t when all of the unassigned z ones get assigned , the Unassigned In terface Zones group b ox will b ecome hidden, in or der t o simplify the user in terface. 6.If you need t o revise an y of the e xisting mesh in terfaces (f or e xample , if you w ant to enable the Coupled Wall option), mak e a selec tion fr om the Mesh In terfaces list, click Edit..., and then c omplet e the setup in the Edit M esh In terfaces D ialog Box (p.3813 ) tha t op ens. Figur e 6.43: The E dit M esh In terfaces D ialo g Box In the Edit M esh In terfaces dialo g box, selec t the Mesh In terfaces you w ant to change , revise the settings , and click Apply .You c an edit the Interface Name and/or the Interface Zones tha t mak e up the in terface (pr ovided tha t the z ones y ou selec t are unassigned and lo cated appr opriately), though such changes ar e only allo wed if y ou selec t a single in terface.You c an selec t one or mor e interfaces and enable the f ollowing Interface Options ; not e tha t you c an click the butt on t o group the in terfaces in the list b y their cur rently enabled in terface option(s), which allo ws you t o selec t / deselec t all those of a par ticular t ype by simply click ing the t op-le vel br anch. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 758Reading and M anipula ting M eshes•Enable Coupled Wall if you w ould lik e to mo del a ther mally c oupled w all b etween t wo fluid z ones tha t shar e a non-c onformal in terface. Imp ortant In the c ase of a solid-t o-solid z one in terface of diff erent ma terials or a fluid-t o-solid zone in terface, by default it is tr eated as a c oupled w all.Therefore, no ac tion is r equir ed in the Edit M esh In terfaces dialo g box to set up such an in terface. •Enable the Matching option if only in ternal z ones should b e created (tha t is, interior or w all / shado w pairs), sinc e the in terface zones on b oth sides ar e aligned .With the Matching option, even in terface zones tha t are not p erfectly aligned ar e treated as if the y are; however, if the discr epanc y between the interface zones on b oth sides e xceeds default thr esholds , then w arning messages will b e displa yed. See Matching Option (p.748) for mor e inf ormation ab out the r ecommended uses of this option. •Enable the Mapp ed option when ther e is p enetr ation or lar ge gaps b etween in terface zones . Note tha t at least one side of the in terface must c onsist of only solid z ones . For additional inf ormation, see The Mapp ed Option (p.749). Enable Enable L ocal Toler anc e in the Mapp ed group b ox for the selec ted in terface, if y ou w ant to override the global t oler ance defined f or Mapp ed Toler anc e in the Interface Options D ialog Box (p.3838 ). •Enable Static if and only if y ou k now tha t the in terface zones will not b e mo ving or def orming r elative to each other a t the in terface.This option will r educ e memor y usage and pr ocessing time dur ing the running of the c alcula tion, esp ecially when ther e are man y zones on b oth sides of the in terface.The only options it is c ompa tible with ar e the Coupled Wall and/or Matching options . See The S tatic Op- tion (p.751) for details . Note the f ollowing: •The Periodic B oundar y Condition and Periodic Rep eats options ar e not a vailable in the Edit M esh Interfaces dialo g box, and so c annot b e changed fr om enabled t o disabled (or vic e-versa) f or an e xisting interface; to change them, you must delet e the in terface and cr eate it again with those options r evised . •For in terfaces tha t ha ve the Periodic B oundar y Condition option enabled , you c an edit the Type and Offset from the Edit M esh In terfaces dialo g box. Note tha t the Auto Comput e Offset option must be disabled t o edit the Offset. When all y our changes ar e applied , close the Edit M esh In terfaces dialo g box. 7.The butt ons a t the b ottom of the Mesh In terfaces group b ox allo w you t o tak e fur ther ac tions , such as deleting or dr awing a selec ted in terface. Note the f ollowing: •The Delet e butt on in the Mesh In terfaces dialo g box can only b e used on one mesh in terface at a time . If you w ould inst ead lik e to delet e multiple in terfaces in a single ac tion, you c an selec t them in the tr ee and use the r ight-click menu c ommand . •The Options ... butt on op ens the Interface Options D ialog Box (p.3838 ), which allo ws you t o up date which mesh in terfaces use the mapp ed option and the r elated settings . 8.Additional w all and in terior z ones will b e created (and delet ed) along with the mesh in terfaces. These z ones will b e named as descr ibed in Interface Zones A utoma tic N aming C onventions (p.751), 759Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Non-C onformal M eshesand ar e visible in the tr ee (f or fur ther details , see Interface Zones A utoma tic N aming C onven- tions (p.751)).There ar e times when y ou ma y need t o tak e ac tion on these additional z ones , including the f ollowing: •If the t wo in terface zones did not o verlap en tirely, check the b oundar y zones cr eated f or the non-o verlapping p ortions t o ensur e tha t the y are the pr oper b oundar y type and/or defined ap- propriately.The non-o verlapping z ones ar e list ed in the tr ee (as childr en of the asso ciated in terface boundar y zones), as w ell as in the r elevant Interface dialo g boxes. If the z one t ype is not c orrect, you c an use the Boundar y Conditions Task P age (p.3479 ) to change it; if the z one is not defined appr opriately, double-click it in the tr ee or click the Edit... butt on in the Interface dialo g box, and mak e the nec essar y changes in the dialo g box tha t op ens. •If you ha ve an y Coupled Wall type interfaces, define b oundar y conditions (if r elevant) by up dating the interface wall z ones using the Boundar y Conditions task page . Setup → Boundar y Conditions 9.It is alw ays a go od pr actice to initializ e the solution and r eview y our in terfaces: •You c an visualiz e the mesh in terface(s) y ou ha ve created b y displa ying c ontours of Mesh and Interface Overlap F raction in the Contours D ialog Box (p.3790 ). See Figur e 6.44: Contours of In terface Overlap Fraction (p.761) for an e xample . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 760Reading and M anipula ting M eshesFigur e 6.44: Contours of In terface O verlap F raction •You c an pr int inf ormation in the c onsole ab out the ar eas of the z ones asso ciated with in terfaces either by using the List butt on in the Mesh In terfaces dialo g box or b y en tering the t ext command define/mesh-interface/list , as sho wn in the f ollowing e xample: >define/mesh-interfaces/list List of Mesh Interfaces Interface Name: int:01 Interface Options: Coupled Description Name ID Area Area Percentage --------------------------- --------------------------- ------- ---------------- ----------------- Interface-Zone-1 f-1 18 0.0010104603 Interface-Zone-2 s-1 6 0.0010102915 Non-Overlapping-Zone-Side-1 f-1-non-overlapping 52 0.0001105132 10.936916% Non-Overlapping-Zone-Side-2 s-1-non-overlapping 53 0.0001103031 10.917952% Interface-Wall-Zone-1 int:01-wall1-1-1 51 0.0008975386 88.824722% Interface-Wall-Zone-2 int:01-wall1-1-1-shadow 54 0.0008975386 88.839561% The Area P ercentage for int:01-side1-w all-f-1 is c alcula ted as the ar ea of int:01-side1-w all-f- 1 divided b y the ar ea of f-1.The Area P ercentage for int:01-w all1-1-1-shado w is c alcula ted as 761Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Non-C onformal M eshesthe ar ea of int:01-w all1-1-1-shado w divided b y the ar ea of s-1.The r emaining ar ea p ercentages are calcula ted in a similar manner . 10.For d ynamic meshes , by default an y motion is aut oma tically tr ansf erred acr oss a mesh in terface when only one side is mo ving as a r esult of user-defined or sy stem c oupling motion, to ensur e that the c oupling is main tained on b oth sides .To change the metho d by which the displac emen t of the passiv e no des is c alcula ted or t o disable this tr ansf er alt ogether , use the define/mesh- interfaces/transfer-motion-across-interfaces? text command . With r egar d to the metho d by which the motion is tr ansf erred, you ha ve two options: transfer- displacements (the default) in terpolates no dal displac emen t from the ac tive side of the in terface to the passiv e side , and is r ecommended when ther e ar e gaps and/or p enetr ations in the mesh interface tha t must b e main tained;project-nodes projec ts the passiv e no des on to the fac es of ac tive side , and is r ecommended when the ac tive side under goes signific ant tangen tial motion (as only the nor mal displac emen t is eff ectively tr ansf erred t o the passiv e side in this metho d). For further details , see Transf erring M otion A cross a M esh In terface (p.765). Note For c ase files in which the in terface was cr eated in ANSY S Fluen t version 17.2 or ear lier, you may reduc e qualit y issues (such as lef t-handed fac es) and/or c onvergenc e pr oblems if y ou recreate the in terface in v ersion 18.0 or la ter b y en tering the f ollowing Scheme c ommand in the c onsole:(recreate-sliding-interfaces) . 6.5.4.1. Manuall y Creating Mesh Int erfaces While it is p ossible t o cr eate every type of mesh in terface using the manual metho d, it is only nec essar y when y ou w ant your in terface to use the p eriodic or p eriodic r epeats option. For all other t ypes it is mor e convenien t to use the aut oma tic metho d (as descr ibed in the pr eceding sec tion), esp ecially when y ou ha ve man y interface zones and/or ar e unfamiliar with their names / lo cations . To manually cr eate a mesh in terface, you will use the Create/Edit M esh In terfaces D ialog Box (p.3794 ), which is op ened b y click ing the Manual C reate... butt on in the Mesh In terfaces D ialog Box (p.3852 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 762Reading and M anipula ting M eshesFigur e 6.45: The C reate/Edit M esh In terfaces D ialo g Box 1.Enter a name f or the in terface in the Mesh In terface text-en try box. 2.Specify the in terface zones tha t mak e up the mesh in terface by selec ting one or mor e zones in the Inter- face Zones S ide 1 list and one or mor e zones in the Interface Zones S ide 2 list. Note tha t you must selec t only one z one p er side if y ou plan t o use the p eriodic or p eriodic r epeats option. Imp ortant If one of y our in terface zones is much smaller than the other , you should sp ecify the smaller z one as Interface Zones S ide 1 to impr ove the accur acy of the in tersec tion calcula tion. 3.Enable the desir ed Interface Options : •Enable Periodic B oundar y Condition to create a non-c onformal p eriodic b oundar y condition in terface. –Selec t either Transla tional or Rota tional as the p eriodic b oundar y condition Type to define the type of p eriodicit y. 763Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Non-C onformal M eshes–Retain the enabled default setting of Auto Comput e Offset if you w ant ANSY S Fluen t to aut oma t- ically c omput e the off set. After cr eating the in terface, the off sets will b e displa yed in these fields . The fields will b e uneditable when the Auto Comput e Offset is enabled . –Disable Auto Comput e Offset if you decide tha t you do not w ant ANSY S Fluen t to find the off set. In this c ase, you will ha ve to pr ovide the off set c oordina tes or angle in the r equir ed fields , dep ending on whether Transla tional or Rota tional periodicit y is selec ted. Imp ortant →Auto computa tion means tha t the r otational angle or the tr ansla tional off set will b e automa tically c alcula ted and used while cr eating a non-c onformal p eriodic b oundar y condition in terface. However, it still r elies on the Rota tional A xis Or igin and the Ro- tational A xis D irection tha t was en tered f or the c ell z one in the c ell z one c ondition dialo g box (for e xample , the Fluid dialo g box).Therefore, before pr oceeding with the creation of the non-c onformal p eriodic b oundar y condition in terface, you ha ve to correctly en ter the r otational axis f or the c orresponding c ell z one . Note tha t aut o computa tion of the non-c onformal p eriodic b oundar y condition offset do es not mean tha t the Rota tional A xis Or igin and Rota tional A xis Direction are also det ected aut oma tically and up dated. It is still y our r esponsib- ility to set up these v alues c orrectly. →For 3D c ases , the Auto Comput e O ffset option r equir es tha t the p eriodic in ter- faces ar e connec ted b y at least t wo fac e zones tha t meet a t an edge tha t points from one p eriodic z one t o the other ; this edge is used t o calcula te the off set. If necessar y, you c an split a c onnec ting z one in to multiple z ones in or der t o cr eate such an edge pr ior t o cr eating the mesh in terface. •Enable Periodic Rep eats when each of the t wo cell z ones has a single pair of c onformal or non-c on- formal p eriodics adjac ent to the in terface (see Figur e 6.35: Transla tional N on-C onformal In terface with the P eriodic R epeats Option (p.746)).This option is t ypic ally used in c onjunc tion with the sliding mesh model, when simula ting the in terface between a r otor and sta tor. •Other options ar e available , as descr ibed in the pr eceding sec tion. Note tha t only Matching is compa t- ible with Periodic B oundar y Condition , and only Coupled Wall is compa tible with Periodic Rep eats. 4.Click Create/Edit... to cr eate a new mesh in terface. ANSY S Fluen t will aut oma tically cr eate addi- tional w all and/or in terior z ones f or the in terface, which will app ear under Non-O verlapping Zones S ide 1 ,Non-O verlapping Z ones S ide 2 ,Interface Wall Z ones S ide 1 ,Interface Wall Zones S ide 2 , and Interface In terior Z ones . 5.The butt ons a t the b ottom of the dialo g box allo w you t o tak e fur ther ac tions , such as the f ollowing: •If you cr eate an inc orrect mesh in terface, you c an selec t it in the selec tion list and click the Delet e butt on t o delet e it. Any additional w all and/or in terior z ones tha t were created when the in terface was cr eated will also b e delet ed. •To edit an in terface, selec t it in the selec tion list and click Create/Edit..., and then r evise the settings using the Edit M esh In terfaces D ialog Box (p.3813 ) tha t op ens. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 764Reading and M anipula ting M eshes•You c an click the Draw butt on t o displa y interface zones or mesh in terfaces in the gr aphics windo w. Note tha t you c an only selec t and displa y interface zones fr om Interface Zones S ide 1 or Interface Zones S ide 2 if no in terfaces ar e selec ted in the selec tion list and if the z one in question is not y et assigned t o an in terface. After an in terface is defined , you c an selec t the appr opriate mesh in terface and click the Draw butt on t o displa y the z ones under Interface Zones S ide 1 and Interface Zones Side 2 together . Drawing is par ticular ly useful if y ou w ant to check the lo cation of the in terface zones prior t o setting up a mesh in terface. 6.5.4.2. Transferring Motion A cross a Mesh Int erface ANSY S Fluen t allo ws motion t o be sp ecified on either side of a mesh in terface, and in some instanc es, can tr ansf er the motion fr om one side of a mesh in terface to the other .When motion is sp ecified on one side of the in terface (but not on the other) using either User-D efined M otion (p.1359 ) or System Coupling M otion (p.1361 ), by default ANSY S Fluen t will aut oma tically in terpolate and tr ansf er this motion so tha t the c oupling is main tained on b oth sides .To disable this tr ansf er or change the metho d by which the displac emen t of the no des on the passiv e side is c alcula ted, use the f ollowing text command: define → mesh-interfaces → transfer-motion-across-interfaces? When such tr ansf er is disabled , the sides of the mesh in terface ma y separ ate and/or p enetr ate over the c ourse of the simula tion, which ma y lead t o convergenc e difficulties and/or an in valid mesh. When it is enabled , you ha ve the f ollowing options: •the transfer-displacements appr oach (default) This appr oach in terpolates no dal displac emen t from the ac tive side of the in terface to the passiv e side; it uses an in verse-distanc e weigh ted in terpolation, so tha t the closer ac tive no des ha ve mor e influenc e.This ma y be beneficial in situa tions wher e gaps and/or p enetr ations ar e pr esen t at the interface, and the y need t o be main tained as the simula tion pr ogresses . Note tha t an y motion specified tangen tial t o the in terface will also b e in terpolated t o the passiv e side , which c an lead to unin tended mesh dr agging . Figur e 6.46: Transf erring D isplac emen ts •the project-nodes appr oach This appr oach pr ojec ts the no des of the passiv e side of the in terface on to the fac es of the ac tive side , in or der t o main tain c onformity. It is b eneficial in situa tions tha t involve signific ant tangen tial motions on the ac tive side of the in terface, as only the nor mal displac emen t is eff ectively tr ansf erred to the passiv e side . Note tha t for mesh in terfaces tha t involve signific ant gaps or p enetr ation, the project-nodes appr oach ma y cause the mesh t o become in valid. 765Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Non-C onformal M eshesFigur e 6.47: Projec ting N odes Note If you e xpect the motion t o pr oduce lar ge displac emen ts, you should c onsider applying a mesh up date metho d on the c ell z one of the passiv e side (such as smo othing or r emeshing , as descr ibed in Dynamic M esh U pdate M etho ds (p.1267 )). 6.6. Overset M eshes Fluen t allo ws you t o build up the c omputa tional domain fr om o verlapping meshes—also k nown as Chimer a or o verset metho dolo gy.This giv es y ou another w ay to build the c omplet e mesh, in addition to using c onformally c onnec ted c ell z ones and non-c onformal in terfaces. 6.6.1. Introduction 6.6.2. Overset Topologies 6.6.3. Overset D omain C onnec tivit y 6.6.4. Diagnosing O verset In terface Issues 6.6.5. Overset M eshing B est P ractices 6.6.6. Overset M eshing Limita tions and C ompa tibilities 6.6.7. Setting up an O verset In terface 6.6.8. Postpr ocessing O verset M eshes 6.6.9. Writing and R eading O verset F iles 6.6.1. Introduc tion Whereas non-c onformal in terfaces c onnec t cell z ones along ma tching fac e zones , overset in terfaces connec t cell z ones b y interpolating c ell da ta in the o verlapping r egions . For o verset meshing t o be succ essful, the c ell z ones must o verlap sufficien tly. An ad vantage of o verset meshing is tha t the indi- vidual par ts of an o verset mesh c an b e gener ated indep enden tly and with f ewer constr aints than if the par ts had t o fit t ogether c onformally or along non-c onformal in terfaces.This c an mak e it easier t o replac e par ts of a mesh without ha ving t o remesh lar ge par ts or e ven the c omplet e mesh. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 766Reading and M anipula ting M eshesFigur e 6.48: Overset C omp onen t and B ack ground M esh Figur e 6.48: Overset C omp onen t and B ackground M esh (p.767) sho ws a simplified mesh f or a simula tion of flo w over a c ylinder in a duc t.The mesh c onsists of t wo par ts—a back ground mesh r epresen ting the duc t and a separ ate comp onent mesh ar ound the c ylinder .The c ase is set up in F luen t as an overset c ase b y sp ecifying the out er b oundar y of the c ylinder mesh as overset (boundar y type), and by creating an o verset in terface containing the t wo cell z ones .With these t wo steps c omplet e, Fluen t automa tically establishes the nec essar y connec tivit y between the meshes when the flo w is initializ ed. In this pr ocess, cells tha t fall outside the c omputa tional domain ar e classified as dead cells.The c ells wher e the flo w equa tions ar e solv ed ar e referred t o as solve cells.Receptor cells r eceive da ta in terpolated from another mesh. The donor cells—the c ells wher e the r eceptors get their da ta—ar e a subset of the solv e cells. For the ab ove case,Figur e 6.49: Solve Cells A fter Initializa tion (p.767) sho ws the solv e cells of the mesh af ter the flo w is initializ ed. Note tha t in par allel, you c an pr int par tition sta tistics t o get information ab out some of the c ell classific ations , as descr ibed in Interpreting P artition S tatistics (p.3089 ). Figur e 6.49: Solve Cells A fter Initializa tion There is no limit on the numb er of c ell z ones tha t can b e pair ed in an o verset in terface. Fluen t classifies the c ell z ones in an o verset in terface as either back ground or comp onent : •Background z ones ar e the c ell z ones tha t mak e up the back ground mesh of the c omputa tional domain. They must b e conformally c onnec ted and c annot ha ve overset boundar ies. •Comp onen t zones o verlay back ground z ones and ha ve overset boundar ies near wher e the y connec t to the back ground and other c omp onen t zones . Comp onen t zones c an b e conformally c onnec ted. If multiple 767Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Overset M eshescomp onen t zones ar e conformally c onnec ted, at least one of these z ones needs t o ha ve an o verset boundar y. All cell t ypes gener ally supp orted in F luen t are supp orted with o verset meshing , including p olyhedr al cells in 3D .The diff erent zones pair ed in an o verset in terface can ha ve diff erent elemen t types or c an have mix ed elemen t types. Overset meshing in F luen t is c ompa tible with mesh adaption. The mesh z ones of an o verset in terface can b e lo cally adapt ed using all a vailable adaption t ools. Overset meshing c an b e used f or st eady-sta te or tr ansien t solutions . Note tha t for st eady-sta te cases in par allel tha t use the default Metis par titioning , ANSY S Fluen t will aut oma tically r epar tition o verset meshes when the solution is initializ ed or da ta is r ead; a mo del-w eigh ted par titioning tha t is designed for optimal p erformanc e is used . 6.6.2. Overset Topologies There ar e a multitude of c onfigur ations tha t can b e constr ucted b y sup erposing back ground and comp onen t meshes in an o verset in terface. Fluen t analyz es the t opology of an in terface with minimal user input , which r equir es tha t the sup erposed meshes adher e to some t opological constr aints. A case c an ha ve multiple o verset in terfaces, but a c ell z one c an only b elong t o a single in terface.That is, interfaces c annot shar e comp onen t or back ground meshes . It is alw ays possible t o ha ve a single overset in terface for an en tire mo del. However, it is mor e efficien t to declar e multiple in terfaces if the zonal t opology allo ws it. Only including c ell z ones tha t are absolut ely r equir ed in an in terface also in- creases efficienc y. In gener al, most o verset in terfaces will ha ve at least one back ground and one c omp onen t mesh. However, ANSY S Fluen t also allo ws you t o set up o verset in terfaces tha t ha ve no back ground mesh and c onsist only of t wo or mor e comp onen t meshes . An overset in terface can c ontain multiple c omp onen t and back ground meshes , provided tha t the back ground meshes do not in tersec t each other . Currently, non-c onformal in terfaces ar e not fully c ompa tible with o verset meshing . Comp onen t meshes cannot b e connec ted t o a non-c onformal in terface and back ground meshes c annot ha ve non-c onformal interfaces b etween them if the y are par t of the same o verset in terface. The c omp onen t meshes of an o verset in terface ar e allo wed t o overlap arbitr arily and multiple c omp onen t meshes c an b e combined t o cr eate an objec t of in terest. However, an imp ortant topological constr aint is tha t ph ysical b oundar y zones (w all, inlet , outlet , symmetr y, and so on) ar e not allo wed t o intersec t each other .That is, a w all b oundar y cannot cr oss another w all b oundar y. For e xample , in the mo del shown in Figur e 6.48: Overset C omp onen t and B ackground M esh (p.767), the c omp onen t mesh c annot be plac ed such tha t its w all b oundar y zone in tersec ts with the w all of the back ground mesh. Overset b oundar ies c an in tersec t with other o verset b oundar ies and with ph ysical b oundar ies. In Fig- ure 6.48: Overset C omp onen t and B ackground M esh (p.767) the o verset b oundar y of the c omp onen t mesh e xtends outside of the in tended c omputa tional domain, crossing the w all b oundar y of the back ground mesh—this is allo wed.Figur e 6.50: Valid O verset M eshes with C omp onen ts in C lose Proximit y (p.769) sho ws a v alid c onfigur ation of thr ee c ylinders in pr oximit y (none of the ph ysical boundar ies in tersec t with other ph ysical b oundar ies). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 768Reading and M anipula ting M eshesFigur e 6.50: Valid O verset M eshes with C omp onen ts in C lose P roximit y Physical b oundar y zones ar e allo wed t o overlap, tha t is, a w all b oundar y (or par ts of a w all b oundar y) can b e coinciden t with another w all b oundar y, as long as the y do not cr oss.This p owerful func tionalit y lets y ou build a b ody from o verlapping par ts or mo dify a b ody by adding par ts.Figur e 6.51: Second Comp onen t Modifying Existing B ody (p.769) sho ws an o verset c onfigur ation wher e a sec ond c omp onen t mesh is added t o an e xisting b ody to mo dify its shap e. Fluen t analyz es and aut oma tically det ects the overlapping b oundar ies (w alls in this c ase) of the diff erent meshes in an o verset in terface, when deciding which c ells ar e solv e cells and which c ells ar e dead c ells. Figur e 6.51: Second C omp onen t Modifying E xisting B ody Note that par t of the w all b oundar y of mesh A lays on t op of par t of the w all b oundar y of mesh B, overlap- ping it , but the w alls do not cr oss or int ersec t. Figur e 6.52: Existing B ody Modific ation A fter Initializa tion (p.770) sho ws the solv e cells of the mesh after the flo w field is initializ ed. 769Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Overset M eshesFigur e 6.52: Existing B ody M odific ation A fter Initializa tion The pr evious e xample sho ws a c ase wher e ph ysical b oundar ies o verlap b etween t wo comp onen t meshes . Overlapping b oundar ies c an also e xist b etween c omp onen t and back ground meshes . If a b ody can only b e built fr om c omp onen ts tha t ha ve in tersec ting b oundar ies, then y ou must use a collar mesh t o pr operly connec t them. A c ollar mesh is an additional c omp onen t mesh tha t bridges the in tersec ting ph ysical b oundar ies, essen tially tr ansf orming the in tersec tion pr oblem (not allo wed) into a pr oblem of o verlapping b oundar ies (allo wed). Figur e 6.53: Multiple C omp onen ts Bridged b y Collars M eshes (p.770) sho ws an o verset in terface consisting of t wo comp onen t meshes tha t ha ve in- tersec ting w all b oundar ies.Two collar meshes (lab eled C and D) are manually cr eated t o correctly define the c onnec tivit y wher e the w all b oundar ies of the or iginal c omp onen t meshes (lab eled A and B) intersec t.The w all b oundar ies of meshes C and D overlap with the w all b oundar ies of meshes A and B. Figur e 6.53: Multiple C omp onen ts Br idged b y Collars M eshes Figur e 6.54: Multiple C omp onen ts with C ollar M eshes Initializ ed (p.771) sho ws the r esulting solv e cells after the flo w is initializ ed.The c ollar meshes ac t as fillet meshes tha t plac e the ac tual b oundar y inter- sections in to the in terior of the b ody and outside of the fluid domain. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 770Reading and M anipula ting M eshesFigur e 6.54: Multiple C omp onen ts with C ollar M eshes Initializ ed Special c onsider ations ar e requir ed when y ou in tend t o add a fluid r egion tha t expands the b ounds of an e xisting r egion, as sho wn in Figur e 6.55: Adding F luid t o a R egion U sing C ut C ontrol (p.771). In this e xample , a duc t (A) is mo dified b y adding a c avity (B).The b oundar ies of the t wo meshes in tersec t, and b y default the lo wer b oundar y of the duc t would cut off the added c avity. In or der t o avoid this , you need t o use cut c ontrol to sp ecify tha t the duc t wall is not cutting the c avity cell z one , and , similar ly, that the c avity boundar y is not cutting in to the duc t cell z one . See Hole C utting C ontrol (p.773) for details on the a vailable cut c ontrols.The r esulting mesh f or the duc t / c avity example af ter initializa tion is sho wn in Figur e 6.56: Cut C ontrolled R egion A fter Initializa tion (p.772). Figur e 6.55: Adding F luid t o a Region U sing C ut C ontrol 771Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Overset M eshesFigur e 6.56: Cut C ontrolled Region A fter Initializa tion Baffles (c oupled w alls) ar e permissible in o verset meshing—b oth in back ground and c omp onen t meshes . 6.6.3. Overset D omain C onnec tivit y When an o verset in terface is initializ ed, ther e ar e thr ee main st eps tha t Fluen t complet es to establish connec tivit y between the par ticipa ting z ones: 6.6.3.1. Hole C utting 6.6.3.2. Overlap M inimiza tion 6.6.3.3. Donor S earch 6.6.3.1. Hole C utting Hole cutting is the pr ocess b y which c ells lying outside of the flo w region (tha t is, inside b odies and outside of the c omputa tional domain) ar e mar ked as dead c ells.This is achie ved b y mar king all the cells tha t are cut b y ph ysical b oundar y zones (w all, inlet , outlet , symmetr y, and so on), and mar king seed c ells det ermined t o lie outside the flo w region f or subsequen t flo od filling of dead c ells.The result of this flo od filling is a v alid o verset mesh with maximum mesh o verlap. Figur e 6.57: Overset C omp onen t and B ackground M eshes B efore Hole C utting (p.773) and Fig- ure 6.58: Overset C omp onen t and B ackground M eshes A fter H ole C utting (p.773) sho w an o verset mesh b efore and af ter hole cutting . All of the back ground c ells tha t are bounded or cut b y the c ylinder wall ar e classified as dead dur ing hole cutting .The maximum o verlap mesh sho wn in Figur e 6.58: Over- set C omp onen t and B ackground M eshes A fter H ole C utting (p.773) is a v alid o verset mesh, however, it ma y not b e ideal. An overly lar ge o verlap b etween c omp onen t and back ground meshes is c ompu- tationally inefficien t (the equa tions ar e solv ed in mor e cells than ar e nec essar y). Additionally , the c ell sizes of the o verlapping meshes ma y vary gr eatly—this aff ects the da ta in terpolation and is detr imen tal to solution qualit y. Ideally meshes should tr ansition in r egions of similar r esolution. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 772Reading and M anipula ting M eshesFigur e 6.57: Overset C omp onen t and B ack ground M eshes B efore Hole C utting Figur e 6.58: Overset C omp onen t and B ack ground M eshes A fter H ole C utting 6.6.3.1.1. Hole C utting C ontr ol By default all b oundar y zones (other than o verset b oundar ies) cut all other c ell z ones and mar k dead cells. If this is not the desir ed b ehavior (see Overset Topologies (p.768)), you c an manually sp ecify that a b oundar y zone do es not cut c ertain c ell z ones .This optional cut c ontrol is a vailable using the following t ext command: define → overset-interfaces → cut-control → add A comp onen t mesh with only o verset b oundar ies (f or e xample , a refinemen t mesh z one o verlaying other z ones) will cut in to other mesh z ones a t its c enter and mar k a single dead c ell (cut seed) in the o verlaying mesh z ones .This ac ts as a pilot hole tha t is then enlar ged dur ing the o verlap minim- ization. In c ases wher e all cut b oundar ies of a c omp onen t mesh ar e overlapping with other b ound- aries, you c an f orce cut seeds in all c omp onen t zones using the f ollowing t ext command: define → overset-interfaces → cut-control → cut-seeds → cut-seeds-for-all- component-zones? Cut seeds ar e aut oma tically enabled f or all c omp onen t zones when a cut c ontrol is added . 773Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Overset M eshes6.6.3.2. Overlap M inimization Overlap minimiza tion is used t o minimiz e mesh o verlap among diff erent comp onen t and back ground meshes b y converting additional solv e cells in to receptor c ells and tur ning unnec essar y receptors into dead c ells. During this pr ocess, a solv e cell is tur ned in to a r eceptor c ell if the c ell c an find a suitable donor c ell with higher donor pr iority. By default , smaller c ells ha ve a higher donor pr iority. Thus, in mesh o verlap ar eas, without additional user input the solv er a ttempts t o obtain the solution on the finest lo cal mesh. The r esulting mesh in terface mo ves to an ar ea wher e the meshes ar e mor e compar able in c ell siz e, leading t o better solution qualit y.Figur e 6.59: Overset C omp onen t and B ack- ground M eshes A fter O verlap M inimiza tion (p.774) sho ws the c ylinder c ase fr om the pr evious figur e after the o verlap minimiza tion st ep. Figur e 6.59: Overset C omp onen t and B ack ground M eshes A fter O verlap M inimiza tion Note tha t overlap minimiza tion is not lit erally minimizing the mesh o verlap.The o verlap minimiza tion is based on a flo od filling of r eceptor c ells, wher ever suitable solv e cells with higher donor pr iority can b e found .The r esulting ac tual mesh o verlap dep ends on the lo cal donor pr iority distr ibution. Also not e tha t with o verlap minimiza tion, data in terpolation b etween c ell z ones do es not nec essar ily occur a t the o verset b oundar ies.The pur pose of sp ecifying an o verset b oundar y is pr imar ily to sp ecify that overset mesh c oupling should happ en, and not wher e it should o ccur . You ha ve the option t o sp ecify diff erent donor pr iority metho ds in or der t o control the lo cation of the o verset in terface.The t ext user in terface command define/overset-interfaces/op- tions/donor-priority-method allo ws you t o sp ecify tha t the donor pr iority is based either on the c ell siz e (pr oportional t o the in verse of the c ell v olume) or the b oundar y distanc e (pr oportional to the in verse of the distanc e to the closest b oundar y). Overlap minimiza tion with donor pr iority based on c ell siz e (default) w orks b est if the c omp onen t mesh r esolution is fine near w alls and incr eases away from w alls, to spacings similar t o—or lar ger than—the back ground mesh (see Figur e 6.57: Overset Comp onen t and B ackground M eshes B efore Hole C utting (p.773) for an e xample of this t ype of mesh). If the o verlapping meshes ha ve unif orm and near ly iden tical resolutions , then o verlap minimiza tion based on c ell siz e will not r educ e the o verlap and a donor pr iority based on the b oundar y distanc e should b e used inst ead.The f ollowing t wo figur es illustr ate an o verset mesh b efore and af ter initial- ization wher e a donor pr iority based on b oundar y distanc e is used . Note tha t for the e valua tion of donor pr iorities based on b oundar y distanc e, all b oundar ies (including inlets , outlets , and so on) ar e used f or the distanc e evalua tion. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 774Reading and M anipula ting M eshesFigur e 6.60: Overset M esh B efore Hole C utting Figur e 6.61: Overset M esh A fter M inimiza tion B ased on B oundar y D istanc e You ha ve the option f or additional c ontrol o ver the o verlap minimiza tion pr ocess b y assigning gr id priorities t o comp onen t and back ground meshes , using the t ext user in terface command define/overset-interfaces/grid-priorities . Meshes (tha t is, cell z ones) with higher grid pr iorities ar e favored dur ing the minimiza tion pr ocess, irrespective of the lo cal cell donor pr iority. If two cell z ones ha ve the same gr id pr iority, then the c ell donor pr iorities ar e used f or the o verlap minimiza tion. For e xample , by assigning a higher gr id pr iority to a c oarser mesh, you c an f orce Fluen t to minimiz e the finer mesh and obtain the solution on the c oarser mesh, even if the donor pr iority is based on c ell siz e. Using gr id pr iorities , similar t o using donor pr iority based on b oundar y distanc e, is helpful if lo cal mesh distr ibutions ar e irregular , and pr oduce overlap r egions tha t are irregular as well. Note tha t the gr id pr iorities tak e pr ecedenc e over the donor pr iorities . You ha ve the option of disabling o verlap minimiza tion b y using the t ext command define/overset- interfaces/options/minimize-overlap? .This c ommand is only a vailable globally and applies to all o verset in terfaces in the domain. 775Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Overset M eshes6.6.3.3. Donor S ear ch The donor sear ch is the final st ep in establishing the domain c onnec tivit y. Fluen t sear ches other meshes f or v alid solv e cells f or each r eceptor.The solv e cell c ontaining the c ell c entroid of the r eceptor cell, along with its c onnec ted solv e cells, are used as donor c andida tes for a giv en r eceptor. Each r e- ceptor must ha ve at least one v alid donor c ell. There must b e four or mor e cells in the o verlap of b oth meshes t o ensur e a succ essful donor sear ch. The r eceptor c ells, which f orm the fr inge la yer of a mesh z one , must o verlap sufficien tly with the opp osite mesh, such tha t the y find v alid solv e cells as donors . For an e xample of v alid mesh o verlap, see Figur e 6.62: Valid O verlap (p.776). Figur e 6.62: Valid O verlap 6.6.4. Diagnosing O verset In terface Issues Topology det ection of o verset in terfaces in F luen t is aut oma tic and do es not r equir e user input. However, for it t o work well, it requir es tha t the pr ovided meshes ar e of sufficien t qualit y, par ticular ly when dealing with meshes tha t ha ve overlapping b oundar ies. Overset meshes ar e built fr om par ts tha t can b e meshed indep enden tly, which c an lead p eople t o think of this as a much simpler pr ocess f or mesh gener ation. This is not alw ays the c ase, as c onsider able though t is of ten r equir ed t o gener ate go od meshes f or the individual c omp onen ts to avoid pr oblems during o verset in terface initializa tion. If you ar e fac ed with issues dur ing the initializa tion of an o verset in terface, ther e is most of ten no r e- covery without mak ing changes t o the mesh. You must analyz e the c ause of the issue , using the available p ostpr ocessing and diagnostic t ools, and impr ove the mesh b efore the simula tion c an c on- tinue . When diagnosing o verset in terface failur es, it c an b e convenien t to use the t ext commands define/overset-interfaces/intersect and define/overset-interfaces/clear (available af ter enabling the e xpert tools a vailable under define/overset-interfaces/op- tions/expert ) to execut e and clear the hole cutting without ha ving t o initializ e the solution. The issues most of ten enc oun tered ar e: 6.6.4.1. Flood Filling F ails D uring H ole C utting 6.6.4.2. Donor S earch F ails D ue to Or phan C ells Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 776Reading and M anipula ting M eshes6.6.4.1. Flood Filling F ails D uring H ole C utting These ar e the issues tha t can c ause pr oblems with flo od filling: 6.6.4.1.1. Incorrect Seed C ells 6.6.4.1.2. Leakage B etween O verlapping B oundar ies 6.6.4.1.1. Inc orrect Seed C ells Flood filling of dead c ells will fail if F luen t inad vertently iden tifies seed c ells inside of the fluid z one instead of outside .This c an o ccur as a r esult of c omple xities in the t opology or geometr y of the boundar y zones , or b ecause of mesh r esolution issues . It manif ests itself as an en tire fluid r egion, or a complet e cell z one , being mar ked as dead . This issue c an b e diagnosed b y using the list c ommand with the o verset v erbosity set t o 1 (see Overset In terface listing (p.787)). You c an use the TUI c ommand define/overset-interfaces/debug-hole-cut (available after enabling the e xpert tools a vailable under define/overset-interfaces/options/ex- pert ) to iden tify the pr oblema tic seed c ells.This c ommand allo ws you t o execut e the hole cutting process on a sp ecific o verset in terface and mar k dead and seed c ells. When the flo od fill option of the debug c ommand is disabled , it will cr eate two regist ers with dead cells and seed c ells which y ou c an then displa y using the define/overset-interface/dis- play-cells text command .The dead mar ks sho w the c ells cut b y the ph ysical b oundar y zones . The seed c ells (mar k0 r egist er) sho w the c ell c andida tes tha t will b e used f or flo od filling . If the flo od fill option of the debug c ommand is enabled , Fluen t will then also cr eate a r egist er of the seed c ells fr om wher e flo od filling ac tually star ted (mar k1 r egist er). If flo od filling fails , displa ying these mar k1 c ells is the most efficien t way to det ect the pr oblema tic lo cations in the mo del. It is cr itical tha t all the seed c ells ar e lo cated inside b odies or outside of the c omputa tional domain. If ther e is a seed c ell in the fluid r egion, it will c ause a flo od fill failur e. It is not p ossible t o recover from flo od filling failur e without mak ing changes t o the mo del. 6.6.4.1.2. Leak age B etween O verlapping B oundaries If no bad seed c ells ar e found , as descr ibed in Incorrect Seed C ells (p.777), and ther e ar e overlapping boundar ies, it is lik ely tha t the o verlapping b oundar ies do not ma tch sufficien tly and the flo od filling of dead c ells leaks fr om the inside of the b ody to the outside . As a r esult , a complet e cell z one c an disapp ear, due t o ha ving only dead c ells.The p ermissible t oler ance between o verlapping b oundar y zones is a t most one c ell-siz e in the w all nor mal dir ection. This c an b e restrictive when dealing with prisma tic b oundar y layer meshes with high c ell asp ect ratios a t the w all. If your mo del suff ers fr om this leak age, you must impr ove the qualit y of the mesh, by mak ing the o verlapping b oundar y zones match b etter. 6.6.4.2. Donor S ear ch F ails D ue t o O rphan C ells If a r eceptor c ell c annot find a v alid donor c ell, then it b ecomes an orphan cell.The pr esenc e of or phan cells gener ally indic ates tha t ther e is insufficien t overlap b etween meshes or tha t the mesh r esolutions do not ma tch w ell. As a r esult , the r eceptors ar e either finding no c andida te donor c ells, or in valid candida tes (dead or r eceptor c ells). 777Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Overset M eshesOrphan c ells c an b e an issue when w alls of diff erent meshes ar e in pr oximit y.You must ha ve at least four c ells in a gap , such as the ones b etween the w alls in Figur e 6.50: Valid O verset M eshes with Comp onen ts in C lose P roximit y (p.769), in or der t o ha ve a go od connec tion b etween the meshes—other wise or phan c ells ar e created.When a r eceptor o verlays another r eceptor, it b ecomes an or phan. See Figur e 6.63: Invalid O verlap C reating Or phans (p.778) for an e xample of insufficien t overlap c ausing the cr eation of or phan c ells. For inf ormation on visualizing or phan c ells, see Postpr ocessing O verset Meshes (p.783).Figur e 6.62: Valid O verlap (p.776) sho ws meshes o verlapping sufficien tly t o avoid the creation of or phan c ells. Figur e 6.63: Invalid O verlap C reating Or phans You c an mar k the or phan c ells, as descr ibed in Overset C ell M arks (p.787), which will lik ely indic ate wher e the mesh o verlap must b e incr eased . Sometimes , incr easing the mesh r esolution c an lead t o a sufficien t incr ease in mesh o verlap. If mesh r esolution is the issue , you c an also use lo cal mesh ad- aption, along with mesh mo dific ation, to refine the mesh. Most of ten the mesh r equir ing adaption is the mesh wher e the or phan should find its donors , and not the mesh z one c ontaining the or phan. If the pr esenc e of or phan c ells in the simula tion is una voidable and y ou pr oceed with a c alcula tion, by default the solv er applies a numer ical tr eatmen t tha t attempts t o assign r easonable v alues t o the orphan c ells.This tr eatmen t has b een f ound t o pr event div ergenc e in some instanc es, allo wing the solution t o pr oceed; however, the or phan c ell tr eatmen t do es not guar antee the solution qualit y and robustness a pr iori.The succ ess of this tr eatmen t is c ase dep enden t, and difficult t o pr edic t based on or phan c ell c oun ts. It is ther efore highly r ecommended tha t you mak e every eff ort to elimina te orphan c ells b y mo difying the mesh, as descr ibed pr eviously . 6.6.5. Overset M eshing B est P ractices Receptor and donor c ell siz es should b e compar able t o ensur e tha t interpolation er rors ar e minimiz ed. You c an manually adapt the mesh t o reduc e the misma tch b etween donors and r eceptors. You must ha ve a minimum of f our c ells in a gap t o cr eate a v alid o verset in terface, but a higher numb er is r ecommended t o ensur e robust c oupling b etween meshes and t o pr event the cr eation of orphan c ells (see Figur e 6.63: Invalid O verlap C reating Or phans (p.778) and Figur e 6.62: Valid O ver- lap (p.776)). It is r ecommended tha t you star t transien t simula tions fr om a c onverged st eady-sta te solution. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 778Reading and M anipula ting M eshesIf you ar e experiencing star tup issues with a st eady-sta te case, it is r ecommended tha t you r amp-up to the final b oundar y conditions . For e xample , you c an b egin with a lo wer inlet v elocity and a higher viscosity to establish flo w, before incr easing t o the tar get v elocity and the desir ed final ma terial properties. When using aut oma tic timest ep c alcula tion f or the pseudo-tr ansien t metho d, it is r ecommended tha t you use the user-defined length sc ale option. If you r eplac e a z one tha t is par t of an o verset in terface, you should either r einitializ e the solution or patch the solution on the r eplac ed z one(s) b efore continuing with the c alcula tion. It is r ecommended tha t you use the double-pr ecision solv er for o verset mesh simula tions . Closed domain c ases ar e defined as setups tha t do not ha ve a flo w inlet or outlet b oundar y; this t ype of setup is not supp orted with o verset meshing if the w orking fluid is inc ompr essible . If such a setup is una voidable , creating a small pr essur e-outlet b oundar y far a way from the r egion of in terest is r ecom- mended b efore attempting t o run the c ase using o verset meshes . For d ynamic and sliding mesh c ases , not e the f ollowing: •The ideal time st ep siz e should b e chosen such tha t the r elative mesh motion do es not e xceed the length of the smallest c ell a t the o verset in terface for a giv en time st ep.The mesh length used f or calcula ting the time st ep should b e restricted t o cells in the o verset o verlap r egion. This ensur es a mor e gr adual e volution of the o verset in terface with the motion and is r ecommended f or b etter ac- curacy and stabilit y. •In gener al, the motion of the o verset in terface ma y change the sta tus f or individual c ells fr om dead to receptor or solv e, and vic e versa. The e xact instanc es dep end on the r elative mesh siz es of the moving c ell z ones par ticipa ting in the o verset in terface, the magnitude of the r elative mesh v elocity, and the time st ep siz e.There is cur rently no mechanism t o elimina te this t ype of c ell sta tus change for gener al cases . •While the solv er is c apable of handling the c ell sta tus change , it is r ecommended tha t you ac tively monit or these instanc es b y setting the o verset mesh v erbosity to 1 using the define/overset- interface/options/verbosity text command .With such a v erbosity, the solv er reports the instanc es of dead t o solv e cells in the c onsole . Keeping these t o a minimum is highly r ecommended for b etter accur acy and stabilit y. •Do not ha ve lar ge v ariations in mesh r esolution in the motion pa th tha t could tr igger lar ge changes in the o verset in terface as the motion pr oceeds .The use of gr id pr iorities c an minimiz e lar ge v ariations in the o verset in terface. You c an sp ecify tha t the o verset in terfaces use either the least squar es in terpolation metho d (the default) or the in verse distanc e in terpolation metho d by using the f ollowing t ext command . solve → set → overset → interpolation-method 6.6.6. Overset M eshing Limita tions and C ompa tibilities Overset meshing has the f ollowing limita tions and c ompa tibilities: 6.6.6.1. Limitations Overset meshing cur rently has the f ollowing limita tions: 779Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Overset M eshes•Overset in terfaces c annot c ontain solid cell z ones . •Comp onen t meshes c annot b e connec ted t o a non-c onformal in terface. •Background meshes c annot ha ve non-c onformal in terfaces b etween them if the y are par t of the same overset in terface. •Comp onen t zones c annot ha ve periodic boundar y conditions . •Background z ones c annot ha ve overset boundar ies. •Comp onen t mesh b oundar ies c annot o verlap with c oupled w alls. •FMG initializa tion is not a vailable . •The F AS multigr id scheme is not used . •Implicit r esidual smo othing c annot b e enabled . •Overset meshing is not supp orted f or inc ompr essible flo ws in a closed domain. •The use of no de w eigh ts for no de-based gr adien ts in p ostpr ocessing is not a vailable f or cases with o verset meshes . 6.6.6.2. Compatibilities Overset meshing is c ompa tible with the tr ansien t and st eady-sta te solv ers. Both laminar and turbulen t flow regimes with hea t transf er ar e allo wed as w ell as non-p orous single phase flo ws, and Volume of Fluid ( VOF) and mix ture multiphase flo ws.These applic ations ar e valid with o verset f or the list ed solv er options and c onfigur ations . Unless other wise sp ecified , consider all other solv er features and models t o be unsupp orted. Supp orted Options and M odels: •Pressur e-based solv er using: –2D (planar and axisymmetr ic) and 3D flo ws in the absolut e velocity formula tion –Compr essible flo ws –Cell-based gr adien t metho ds:Green-G auss C ell B ased and Least S quar es C ell B ased –All pr essur e interpolation schemes –First-or der and sec ond-or der spa tial schemes –Coupled scheme f or pr essur e-velocity coupling –Pseudo tr ansien t metho d –First-or der and (f or sta tionar y meshes only) sec ond-or der and b ounded sec ond-or der tr ansien t formu- lations •Densit y-based solv er using: –2D (planar and axisymmetr ic) and 3D flo ws in the absolut e velocity formula tion Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 780Reading and M anipula ting M eshes–Compr essible flo ws –Cell-based gr adien t metho ds:Green-G auss C ell B ased and Least S quar es C ell B ased –All convective flux t ypes (R oe-FDS, AUSM, and L ow D iffusion R oe-FDS) –First-or der and sec ond-or der spa tial schemes –Pseudo tr ansien t metho d –First-or der and (f or sta tionar y meshes only) sec ond-or der and b ounded sec ond-or der tr ansien t formu- lations • - turbulenc e mo dels (S tandar d, RNG, and R ealizable) • - turbulenc e mo dels (S tandar d, BSL, and SST ) •Spalar t-Allmar as turbulenc e mo del •Species tr ansp ort mo del: –single-phase flo w only –reactions must b e disabled •VOF mo dels: –Open channel flo w and sur face gr avity waves –Cavitation and e vaporation/c ondensa tion mass tr ansf er •Mixture multiphase mo del: –Non-gr anular flo ws –Cavitation and e vaporation/c ondensa tion mass tr ansf er •Cavitation and e vaporation/c ondensa tion mass tr ansf er in VOF/M ixture multiphase applic ations •Non-gr anular flo ws in multiphase applic ations •Dynamic and sliding meshes with the first-or der tr ansien t formula tion •User-defined sc alars •User-defined func tions (f or inf ormation ab out o verset-sp ecific macr os tha t can b e useful when writing user-defined func tions , see Overset M esh L ooping M acros in the Fluen t Customiza tion Manual ) •All AMG options •All boundar y conditions ar e supp orted with the f ollowing limita tions: –Non-in terior fac e zone b oundar y conditions—e xhaust fan, inlet v ent, intake fan, outlet v ent—ar e only allowed on c ell z ones tha t are not par ticipa ting in an o verset in terface 781Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Overset M eshes–Interior fac e zone b oundar y conditions—fan, porous-jump , and r adia tor—ar e only allo wed on c ell z ones that are not par ticipa ting in an o verset in terface •Cell z one c onditions –Source terms ma y only b e defined on c ell z ones not par ticipa ting in an o verset in terface –Fixed v alues ma y only b e defined on c ell z ones not par ticipa ting in an o verset in terface –Multiple R eference Frame (MRF) mo del •Hybrid and standar d initializa tion •An overset meshing solution ma y be obtained on an y mesh t ype, including manually adapt ed meshes 6.6.7. Setting up an O verset In terface Onc e you ha ve read all of the r elated meshes in to Fluen t, use the f ollowing st eps t o setup an o verset interface. 1.Change the b oundar y zones of c omp onen t meshes t o overset (boundar y type), wher e needed . Imp ortant You must c orrectly sp ecify the overset boundar ies f or all z ones in an o verset in terface before creating the o verset in terface. (Onc e overset in terfaces ar e created y ou c annot change an y boundar ies fr om overset to another t ype or fr om another t ype to overset .) Setup → Boundar y Conditions → Type → overset 2.Create an o verset in terface between the c ell z ones tha t must b e coupled . A case c an ha ve multiple in ter- faces. Each in terface must ha ve at least one back ground and one c omp onen t mesh. Domain → Interfaces → Overset Figur e 6.64: Create/Edit O verset In terfaces D ialo g Box a.Enter a name under Overset In terface. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 782Reading and M anipula ting M eshesb.Selec t the z ones of the in terface in the Back ground Z ones and Comp onen t Zones selec tion lists . ANSY S Fluen t allo ws you t o cr eate in terfaces tha t contain only c omp onen t zones; in such cases , you do not selec t a back ground z one , but inst ead selec t two or mor e comp onen t zones . c.Click Create. 3.(optional) U se the t ext user in terface for additional c ontrol o ver the hole cutting st ep of the in terface initializa tion. •If certain b oundar y zones should not cut par ticular c ell z ones , use the define/overset-inter- faces/cut-control/add text command t o set up cut c ontrol. •If comp onen t meshes ha ve no b oundar ies tha t will cut a c ell z one , you c an use the define/overset- interfaces/cut-control/cut-seeds/cut-seeds-for-all-component-zones? text command t o ensur e tha t all c omp onen t zones get cut seeds (see Hole C utting C ontrol (p.773)). 4.(optional) U se the t ext user in terface for additional c ontrol over the o verlap minimiza tion of the o verset interface. It can b e helpful t o revise the default settings if y our o verlapping meshes ha ve unif orm and near ly iden tical resolutions or if lo cal mesh distr ibutions ar e irregular , as this ma y impr ove the c omputa- tional efficienc y and/or the solution qualit y. See Overlap M inimiza tion (p.774) for details . •To sp ecify whether the c ell donor pr iorities used dur ing minimiza tion ar e based on the c ell siz e or dis- tanc e to the near est b oundar y, use the f ollowing t ext command: define → overset-interfaces → options → donor-priority-method •To revise the gr id pr iorities dur ing minimiza tion, use the f ollowing t ext command .The gr id pr iority for each z one is an in teger , and only the r elative values b etween the z ones ma tter. define → overset-interfaces → grid-priorities •To disable o verlap minimiza tion en tirely, use the f ollowing t ext command .This c ommand is only available globally and applies t o all o verset in terfaces in the domain. define → overset-interfaces → options → minimize-overlap? Note tha t these st eps only define an o verset in terface. Hole cutting o ccurs dur ing solution initializa tion. If a c ase c ontains overset face zones , but no defined o verset in terfaces, then F luen t creates a default interface with the name default-overset-interface upon initializa tion. This default o verset interface contains all c ell z ones in the domain. If you k now tha t some c ell z ones do not need t o be included in an o verset in terface, then y ou c an incr ease the solution p erformanc e by manually cr eating the in terface and only including the r elevant back ground and c omp onen t meshes . 6.6.8. Postpr ocessing O verset M eshes Fluen t has se veral overset-sp ecific p ostpr ocessing t ools t o help y ou analyz e/understand the domain connec tivit y.These t ools ar e only a vailable af ter the flo w field is initializ ed and the domain c onnec tivit y is established . 6.6.8.1. Overset M esh D ispla y 6.6.8.2. Overset F ield F unctions 6.6.8.3. Overset C ell M arks 6.6.8.4. Overset In terface listing 6.6.8.5. Overset P ostpr ocessing Limita tions 783Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Overset M eshes6.6.8.1. Overset Mesh D ispla y You c an either visualiz e the c omplet e mesh or just the ac tive cells. If the Overset option is enabled in the Mesh D ispla y dialo g box, by default only solv e cells ar e sho wn. Disabling the Overset option displa ys the c omplet e sur faces. Domain → Mesh → Displa y You ha ve the option t o ha ve receptor c ells displa yed along with the solv e cells when Overset is se- lected.You c an enable this option via the TUI c ommand define/overset-interfaces/op- tions/render-receptor-cells? . Note When displa ying c ontours of p ostpr ocessing quan tities , dead c ell v alues ar e ne ver sho wn, regar dless of whether or not Overset is enabled in the Mesh D ispla y dialo g box. 6.6.8.2. Overset F ield F unc tions There is an Overset C ell Type func tion a vailable in the Cell Inf o... categor y in the Contours D ialog Box (p.3790 ).The in teger func tion v alue dep ends on the o verset c ell t ype: Integer F unc tion Value Cell Type 2 donor 1 solv e 0 receptor –1 orphan –2 dead Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 784Reading and M anipula ting M eshesThis field func tion is also a vailable in the Contours dialo g box. Results → Graphics → Contours → Edit... 1. Selec t Cell Inf o... and Overset C ell Type from the Contours of drop-do wn lists . 2. Choose the sur faces c ontaining the o verset c ells y ou w ant to visualiz e and click Displa y. 785Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Overset M eshesFigur e 6.65: Contours of O verset C ell Type: Back ground M esh Figur e 6.66: Contours of O verset C ell Type: Comp onen t Mesh Figur e 6.65: Contours of O verset C ell Type: Background M esh (p.786) and Figur e 6.66: Contours of Overset C ell Type: Comp onen t Mesh (p.786) displa y a back ground mesh and c omp onen t mesh (se- Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 786Reading and M anipula ting M eshesquen tially) of Overset C ell Type for the c ylinder pr oblem sho wn in Figur e 6.48: Overset C omp onen t and B ackground M esh (p.767). Note If you w ant to displa y or phan c ells, then y ou must enable the TUI c ommand define/overset-interfaces/options/render-receptor-cells? . If the e xpert options ar e enabled under define/overset-interfaces/options/expert , then y ou c an also cho ose t o displa y Overset D onor C oun t and Overset Rec eptor C oun t under Cell Info….The Overset D onor C oun t is filled f or each r eceptor and sho ws the numb er of donors . Similar ly, the Overset Rec eptor C oun t is filled f or donor c ells and sho ws the numb er of r eceptors tha t are referencing the donors . Note that the donor c ounts r eported ar e the maximum numb er of donors a vailable f or the data int erpol- ation. The ac tual numb er of donors used b y the sol ver ma y be less . 6.6.8.3. Overset C ell M arks It can b e difficult t o in terpret contours of o verset c ells in 3D . Often, it is mor e illustr ative to mar k a certain t ype of o verset c ells and displa y these mar ked c ells. Using the t ext command define/overset-interfaces/mark-cells you c an mar k cells of specified o verset c ell t ype (solv e, receptor, donor , orphan, or dead), either globally or on a single c ell zone .This c ommand aut oma tically fills r egist ers tha t can b e displa yed using the define/overset- interfaces/display-cells text command . 6.6.8.4. Overset Int erface listing Use the t ext command define/overset-interfaces/list to pr int overset in terface related information t o the c onsole . If the o verset v erbosity,define/overset-interfaces/op- tions/verbosity , is set t o 1, then c oun ts of each o verset c ell t ype ar e pr inted p er cell z one as well. 6.6.8.5. Overset P ostpr ocessing Limitations Volume in tegrals ar e tak en o ver all solv e cells in the domain. This r esults in double c oun ting wher e solv e cells o verlap, leading t o er rors in v olume in tegrals on o verset meshes . Similar ly, sur face in tegrals, including f orce and momen t reports, will include er rors when tak en on surfaces cr eated f or p ostpr ocessing (such as plane sur faces or r ake sur faces) in r egions wher e solv e cells or b oundar y zones o verlap. If sur face in tegrals ar e tak en on b oundar y zones r ather than cr eated surfaces and/or in a r egion without o verlap, then the sur face in tegrals ar e exact. Imp ortant Errors in in tegral evalua tions sc ale with the siz e of the o verlap. 787Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Overset M eshes6.6.9. Writing and Reading O verset F iles When wr iting o verset c ase files , it is r ecommended tha t you use the hier archic al da ta format (HDF), as in this f ormat the o verset domain c onnec tivit y is sa ved in the c ase file .This mak es it unnec essar y to reestablish the domain c onnec tivit y when r eading an o verset c ase in to a new session. It also guar- antees an iden tical connec tivit y when a c ase is r ead on a diff erent numb er of c omput e no des. For mor e details ab out HDF , see Reading and Writing F iles U sing Hier archic al D ata Format (HDF) (p.589). When y ou wr ite an o verset c ase file in HDF and the c ase has not y et b een initializ ed, ANSY S Fluen t will b y default establish the domain c onnec tivit y pr ior t o wr iting the file .This c an b e disabled using the define/overset-interfaces/options/update-before-case-write? text command , which is a vailable af ter y ou enable the e xpert tools using the define/overset-interfaces/op- tions/expert command . 6.7. Check ing the M esh The mesh check ing c apabilit y in ANSY S Fluen t examines v arious asp ects of the mesh, including the mesh t opology, periodic b oundar ies, simple x coun ters, and (f or axisymmetr ic cases) no de p osition with respect to the axis , and pr ovides a mesh check r eport with details ab out domain e xtents, statistics related t o cell v olume and fac e ar ea, and inf ormation ab out an y pr oblems asso ciated with the mesh. You c an check the mesh b y click ing the Check butt on in the Gener al task page . Setup → Gener al → Check Imp ortant It is gener ally a go od idea t o check y our mesh r ight after reading it in to Fluen t, in or der t o detect an y mesh tr ouble b efore you get star ted with the pr oblem setup . The mesh check e xamines the t opological inf ormation, beginning with the numb er of fac es and no des per cell. A tr iangular c ell (2D) should ha ve 3 fac es and 3 no des, a tetrahedr al cell (3D) should ha ve 4 faces and 4 no des, a quadr ilateral cell (2D) should ha ve 4 fac es and 4 no des, and a he xahedr al cell (3D) should ha ve 6 fac es and 8 no des. Polyhedr al cells (3D) will ha ve an arbitr ary numb er of fac es and no des. Next, the fac e handedness and fac e no de or der f or each z one is check ed.The z ones should c ontain all right-handed fac es, and all fac es should ha ve the c orrect no de or der. The last t opological verification is check ing the elemen t-type consist ency. If a mesh do es not c ontain mixed elemen ts (quadr ilaterals and tr iangles or he xahedr a and t etrahedr a), ANSY S Fluen t will det ermine that it do es not need t o keep tr ack of the elemen t types. By doing so , it c an elimina te some unnec essar y work. For axisymmetr ic cases , the numb er of no des b elow the axis is list ed. Nodes b elow the axis ar e forbidden f or axisymmetr ic cases , sinc e the axisymmetr ic cell v olumes ar e created b y rotating the 2D cell v olume ab out the axis; ther efore no des b elow the axis w ould cr eate nega tive volumes . For solution domains with r otationally p eriodic b oundar ies, the minimum, maximum, average, and prescr ibed p eriodic angles ar e comput ed. A c ommon mistak e is t o sp ecify the angle inc orrectly. For domains with tr ansla tionally p eriodic b oundar ies, the b oundar y inf ormation is check ed t o ensur e tha t the b oundar ies ar e truly p eriodic. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 788Reading and M anipula ting M eshesFinally , the simple x coun ters ar e verified .The ac tual numb ers of no des, faces, and c ells tha t Fluen t has constr ucted ar e compar ed t o the v alues sp ecified in the c orresponding header declar ations in the mesh file. Any discr epancies ar e reported. 6.7.1. Mesh C heck R eport 6.7.2. Repair ing M eshes 6.7.1. Mesh C heck Rep ort When y ou click the Check butt on in the Gener al task page , a mesh check r eport will b e displa yed in the c onsole .The f ollowing is a sample of a succ essful output : Mesh Check Domain Extents: x-coordinate: min (m) = -4.000000e-002, max (m) = 2.550000e-001 y-coordinate: min (m) = 0.000000e+000, max (m) = 2.500000e-002 Volume statistics: minimum volume (m3): 2.463287e-009 maximum volume (m3): 4.508038e-007 total volume (m3): 4.190433e-004 minimum 2d volume (m3): 3.000589e-007 maximum 2d volume (m3): 3.019523e-006 Face area statistics: minimum face area (m2): 4.199967e-004 maximum face area (m2): 2.434403e-003 Checking mesh....................... Done. The mesh check r eport begins b y listing the domain e xtents.The domain e xtents include the minimum and maximum , , and coordina tes in met ers. Then the v olume sta tistics ar e pr ovided , including the minimum, maximum, and t otal c ell v olume in . A nega tive value f or the minimum v olume indic ates tha t one or mor e cells ha ve impr oper con- nectivit y. Cells with a nega tive volume c an of ten b e iden tified and view ed b y creating an iso-v alue field v ariable c ell r egist er (Field Variable (p.2763 )).You c an tr y adapting the mesh t o resolv e the nega tive volume c ells ( Adapting the M esh (p.2705 )).You must elimina te these nega tive volumes b efore continuing the flo w solution pr ocess. Next, the mesh r eport lists the fac e ar ea sta tistics , including the minimum and maximum ar eas in . A value of 0 f or the minimum fac e ar ea indic ates tha t one or mor e cells ha ve degener ated. As with nega tive volume c ells, you must elimina te such fac es. It is also r ecommended t o correct cells tha t ha ve nonz ero fac e ar eas, if the v alues ar e very small. Besides the inf ormation ab out the domain e xtents and sta tistics , the mesh check r eport will also displa y warnings based on the r esults of the checks pr eviously descr ibed.You c an sp ecify tha t the mesh check report displa ys mor e detailed inf ormation ab out the v arious checks and the mesh failur es, by using the f ollowing t ext command pr ior t o performing the mesh check: mesh → check-verbosity You will then b e pr ompt ed t o en ter the le vel of v erbosity for the mesh check r eport.The p ossible levels include: •0 This is the default le vel, and only notifies y ou tha t checks ar e being p erformed (f or e xample , Check ing mesh... ).The r eport will lo ok lik e the pr evious e xample; while w arnings will b e displa yed 789Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Check ing the M eshbelow the domain e xtents and sta tistics , the names of the individual checks will not b e list ed as they are conduc ted. •1 This le vel lists the individual checks as the y are performed (f or e xample ,Check ing r ight-handed cells). Any warnings tha t result will b e displa yed immedia tely b elow the check tha t produced it. •2 This le vel pr ovides the maximum inf ormation ab out the mesh check. The r eport will list the individual checks as the y are performed (f or e xample ,Check ing r ight-handed c ells); any warnings tha t result will b e displa yed immedia tely b elow the check tha t produced it. Additional details ab out the check failur e will also b e displa yed, such as the lo cation of the pr oblem or the aff ected c ells. 6.7.2. Repair ing M eshes If the mesh check r eport indic ates a mesh pr oblem or if y ou r eceive warnings , you c an in vestiga te the extent of the pr oblem b y pr inting the p oor elemen t sta tistics in the c onsole .This c an b e acc omplished using the Rep ort Poor Q ualit y Elemen ts butt on, located a t the b ottom of the Solution M etho ds task page ( Figur e 6.67: The S olution M etho ds Task P age (p.791)). Note tha t this butt on is only a vailable when the mesh has p oor qualit y elemen ts. For mor e inf ormation ab out the Rep ort Poor Q ualit y Ele- men ts feature, see Robustness on M eshes of P oor Q ualit y (p.2694 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 790Reading and M anipula ting M eshesFigur e 6.67: The S olution M etho ds Task P age Alternatively, you c an pr int the p oor elemen t sta tistics via the f ollowing t ext command: mesh → repair-improve → report-poor-elements You c an also visualiz e the in valid and p oor elemen ts b y mar king and displa ying them b y using the Mesh... and Mark Poor E lemen ts selec tions fr om the Field Value of drop-do wn lists of the Field Variable Regist er dialo g box (see Field Variable (p.2763 ) for fur ther details). Similar ly, you c an displa y them using the Contours dialo g box, by selec ting Mesh... and Mark Poor E lemen ts from the Contours of drop-do wn lists . In either c ase, a value of 1 is assigned t o the c ells tha t are iden tified as in valid or poor, as w ell as the c ells tha t are adjac ent to the fac e of an in valid or p oor c ell, and a v alue of 0 is as- signed t o all other c ells. 791Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Check ing the M eshThe mesh check r eport will indic ate if the mesh has pr oblems tha t must b e repair ed, such as lef t- handed fac es and/or fac es tha t ha ve the wr ong no de or der. If repair able failur es ar e det ected b y the mesh check, the Repair butt on in the Domain ribbon tab ( Mesh group b ox) b ecomes a vailable: Domain → Mesh → Repair Using the Repair butt on is the simplest w ay to attempt t o correct your mesh pr oblems . It will a ttempt to correct a numb er of pr oblems iden tified b y the mesh check, including c ells tha t ha ve: •the wr ong no de or der •the wr ong fac e handedness or tha t are not c onvex •faces tha t are small or none xistent •very poor qualit y (see Mesh Q ualit y (p.719) for additional details) Note tha t by default , the Repair butt on will only adjust the p ositions of in terior no des. If you w ant to also mo dify the no des on the b oundar ies of the mesh, use the f ollowing t ext command before you repair the mesh: mesh → repair-improve → allow-repair-at-boundaries The Repair butt on ma y convert degener ate cells in to polyhedr a, based on sk ewness cr iteria (f or mor e information on ho w cells ar e converted, see Converting S kewed C ells t o Polyhedr a (p.800)). If you w ant to ensur e tha t ther e ar e no p olyhedr a in the r epair ed mesh (f or e xample , if y ou if plan on p erforming hanging no de adaption), you must disable such c onversions using the f ollowing t ext command before you r epair the mesh: mesh → repair-improve → include-local-polyhedra-conversion-in-repair If you w ould lik e to only a ttempt t o impr ove the p oor qualit y cells, you c an use the f ollowing t ext command: mesh → repair-improve → improve-quality You c an use the improve-quality text command multiple times , until the mesh is impr oved t o your sa tisfac tion. For gr eater control o ver the degr ee t o which the mesh is impr oved, you c an p erform qualit y-based smo othing (as descr ibed in Smoothing (p.827)). It should b e not ed tha t both the Repair butt on and the improve-quality text command c an b e CPU in tensiv e, if ther e ar e a lar ge numb er of p oor qualit y cells in the mesh. If you ar e not as c oncerned about c ell qualit y, you c an a ttempt t o fix only the lef t-handed fac es and fac es with the wr ong no de order. Begin b y repair ing the no de or der with the f ollowing t ext command: mesh → repair-improve → repair-face-node-order Because the lef t-handed fac es ma y be a r esult of impr oper fac e no de or der, the pr evious t ext command may resolv e both issues a t the same time . Be sur e to perform another mesh check af ter en tering the repair-face-node-order command , to see if the mesh has b een fully r epair ed. If at an y point the mesh check r eveals tha t the mesh c ontains lef t-handed fac es without an y no de or der issues , you c an a ttempt t o repair the fac e handedness b y mo difying the c ell c entroids with the f ollowing text command: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 792Reading and M anipula ting M eshesmesh → repair-improve → repair-face-handedness Onc e again, perform a mesh check t o see if the t ext command w as succ essful. The repair-face- handedness text command is most eff ective for c ells with high asp ect ratios. If the mesh check r eport includes a w arning message such as WARNING: node on face thread 2 has multiple shadows. it indic ates the e xistence of duplic ate shado w no des.This er ror o ccurs only in meshes with p eriodic- type walls.You c an r epair such a mesh using the f ollowing t ext command: mesh → repair-improve → repair-periodic If the in terface is r otationally p eriodic, you will b e pr ompt ed f or the r otation angle . 6.8. Rep orting M esh S tatistics There ar e se veral metho ds for reporting inf ormation ab out the mesh af ter it has b een r ead in to ANSY S Fluen t.You c an r eport the amoun t of memor y used b y the cur rent problem, the mesh siz e, and sta tistics about the mesh par titions . Zone-b y-zone c oun ts of c ells and fac es c an also b e reported. Information ab out mesh sta tistics is pr ovided in the f ollowing sec tions: 6.8.1. Mesh S ize 6.8.2. Memor y Usage 6.8.3. Mesh Z one Inf ormation 6.8.4. Partition S tatistics 6.8.1. Mesh S ize You c an pr int out the numb ers of no des, faces, cells, and par titions in the mesh b y click ing Info and selec ting Size, in the Domain ribbon tab ( Mesh group b ox). Domain → Mesh → Info → Size A par tition is a piec e of a mesh tha t has b een segr egated f or par allel pr ocessing (see Parallel P ro- cessing (p.3045 )). A sample of the r esulting output f ollows: Mesh Size Level Cells Faces Nodes Partitions 0 7917 12247 4468 1 2 cell zones, 11 face zones. If you ar e in terested in ho w the c ells and fac es ar e divided among the diff erent zones , click Info and selec t Zones , in the Domain ribbon tab ( Mesh group b ox), as descr ibed in Mesh Z one Inf orma- tion (p.795). If you ar e using the densit y-based c oupled e xplicit solv er, the mesh inf ormation will b e pr inted f or each gr id le vel.The gr id le vels r esult fr om cr eating c oarse gr id le vels f or the F AS multigr id convergenc e 793Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Reporting M esh S tatisticsacceleration (see Full-A pproxima tion S torage (F AS) M ultigr id in the Theor y Guide ). A sample of the resulting output is sho wn b elow: Mesh Size Level Cells Faces Nodes Partitions 0 7917 12247 4468 1 1 1347 3658 0 1 2 392 1217 0 1 3 133 475 0 1 4 50 197 0 1 5 17 78 0 1 2 cell zones, 11 face zones. 6.8.2. Memor y Usage During an ANSY S Fluen t session y ou ma y want to check the amoun t of memor y used and allo cated in the pr esen t analy sis. ANSY S Fluen t has a f eature tha t will r eport the f ollowing inf ormation: the numb ers of no des, faces, cells, edges , and objec t pointers (gener ic pointers f or v arious mesh and graphics utilities) tha t are used and allo cated; the amoun t of ar ray memor y (scr atch memor y used f or surfaces) used and allo cated; and the amoun t of memor y used b y the solv er pr ocess. You c an obtain this inf ormation b y click ing Info and selec ting Memor y Usage , in the Domain ribbon tab ( Mesh group b ox). Domain → Mesh → Info → Memor y Usage The memor y inf ormation will b e diff erent for Linux and Windo ws systems . 6.8.2.1. Linux S ystems On Linux sy stems , not e the f ollowing definitions r elated t o pr ocess memor y inf ormation: •Process sta tic memor y is essen tially the siz e of the c ode itself . •Process d ynamic memor y is the allo cated heap memor y used t o store the mesh and solution v ariables . •Process t otal memor y is the sum of sta tic and d ynamic memor y. 6.8.2.2. Windo ws Systems On Windo ws systems , not e the f ollowing definitions r elated t o pr ocess memor y inf ormation: •Process ph ysical memor y is the allo cated heap memor y cur rently r esiden t in R AM. •Process vir tual memor y is the allo cated heap memor y cur rently sw app ed t o the Windo ws system page file. •Process t otal memor y is the sum of ph ysical and vir tual memor y. Note the f ollowing: •The memor y inf ormation do es not include the sta tic (c ode) memor y. •Cortex runs in its o wn pr ocess, so the heap memor y value includes st orage f or the mesh and solution variables only . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 794Reading and M anipula ting M eshesOn Windo ws systems , you c an also get mor e inf ormation on the ANSY S Fluen t process (or pr ocesses) by using the Task M anager (see y our Windo ws do cumen tation f or details). Examples of pr ocess image names ar e as f ollows:cx1950.exe (Cortex),fl1950.exe (solv er host), and fl_mpi1950.exe (solv er no de). 6.8.3. Mesh Z one Inf ormation You c an pr int inf ormation in the c onsole ab out the no des, faces, and c ells in each z one the b y click ing Info and selec ting Zones , in the Domain ribbon tab ( Mesh group b ox). Domain → Mesh → Info → Zones The mesh z one inf ormation includes the t otal numb er of no des and , for each fac e and c ell z one , the numb er of fac es or c ells, the c ell (and , in 3D , face) type (tr iangular , quadr ilateral, and so on), the boundar y condition t ype, and the z one ID . Sample output is sho wn b elow: Zone sizes on domain 1: 21280 hexahedral cells, zone 4. 532 quadrilateral velocity-inlet faces, zone 1. 532 quadrilateral pressure-outlet faces, zone 2. 1040 quadrilateral symmetry faces, zone 3. 1040 quadrilateral symmetry faces, zone 7. 61708 quadrilateral interior faces, zone 5. 1120 quadrilateral wall faces, zone 6. 23493 nodes. 6.8.4. Partition S tatistics You c an pr int mesh par tition sta tistics in the c onsole b y click ing Info and selec ting Partitions , in the Domain ribbon tab ( Mesh group b ox). Domain → Mesh → Info → Partitions The sta tistics include the numb ers of c ells, faces, interfaces, and neighb ors of each par tition. See Inter- preting P artition S tatistics (p.3089 ) for fur ther details , including sample output. 6.9. Converting the M esh t o a P olyhedr al M esh Since the ANSY S Fluen t solv er is fac e based , it supp orts p olyhedr al cells.The ad vantages tha t polyhedr al meshes ha ve sho wn o ver some of the t etrahedr al or h ybrid meshes is the lo wer o verall c ell c oun t, almost 3-5 times lo wer for unstr uctured meshes than the or iginal c ell c oun t. Currently, ther e ar e thr ee options in ANSY S Fluen t tha t allo w you t o convert your non-p olyhedr al cells t o a p olyhedr a: •Converting the en tire domain in to polyhedr al cells (applic able only f or meshes tha t contain t etrahedr al and/or w edge c ells). •Converting sk ewed t etrahedr al cells t o polyhedr al cells. •Converting c ells with hanging no des/edges t o polyhedr al cells. Information ab out p olyhedr al mesh c onversion is pr ovided in the f ollowing sec tions: 6.9.1. Converting the D omain t o a P olyhedr a 6.9.2. Converting S kewed C ells t o Polyhedr a 6.9.3. Converting C ells with Hanging N odes / E dges t o Polyhedr a 795Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Converting the M esh t o a P olyhedr al M esh6.9.1. Converting the D omain t o a P olyhedr a Conversion of a mesh t o polyhedr a only applies t o 3D meshes tha t contain t etrahedr al and/or w edge cells. To begin the c onversion pr ocess, ANSY S Fluen t aut oma tically dec omp oses each non-he xahedr al cell into multiple sub-v olumes c alled “duals ” (the shaded r egions seen in the 2D e xample in Figur e 6.68: Con- nection of E dge C entroids with F ace Centroids (p.797)). Each dual is asso ciated with one of the or iginal nodes of the c ell.These duals ar e then agglomer ated in to polyhedr al cells ar ound the or iginal no des. Therefore, the c ollec tion of duals fr om all c ells shar ing a par ticular no de mak es up each p olyhedr al cell (see Figur e 6.69: A P olyhedr al C ell (p.797)).The no de tha t is no w within the p olyhedr al cell is no longer needed and is r emo ved. To better understand ho w duals ar e formed , you c an c onsider the str aigh tforward case of a t etrahedr al mesh. Each of the c ells ar e dec omp osed in the f ollowing manner : first , new edges ar e created on each face between the fac e centroid and the c entroids of the edges of tha t fac e.Then, new fac es ar e created within the c ell b y connec ting the c ell c entroid t o the new edges on each fac e.These in terior fac es establish the b oundar ies b etween the duals of a c ell, and divide the c ell in to 4 sub-v olumes .These dividing fac es ma y be adjust ed and mer ged with neighb oring fac es dur ing the agglomer ation pr ocess, in or der t o minimiz e the numb er of fac es on the r esultan t polyhedr al cell. Note By default , ANSY S Fluen t checks the asp ect ratio of b oundar y layer cells and if the asp ect ratios ar e high, ANSY S Fluen t asks whether y ou w ant to pr eser ve cells a t the b oundar y layer (which c ould b e useful f or k eeping c ell c oun ts lo w when r etaining b oundar y features).You can o verride this default with the t ext command:mesh/polyhedra/options/pre- serve-boundary-layer? (for additional inf ormation ab out these options , see mesh/ in the Fluent Text Command List ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 796Reading and M anipula ting M eshesFigur e 6.68: Connec tion of E dge C entroids with F ace Centroids Figur e 6.69: A P olyhedr al C ell Imp ortant Hexahedr al cells ar e not c onverted t o polyhedr a when the domain is c onverted, except when the y border non-he xahedr al cells.When the neighb oring c ell is r econfigur ed as 797Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Converting the M esh t o a P olyhedr al M eshpolyhedr a, the shar ed fac e of the he xahedr al cell is dec omp osed in to multiple fac es as w ell, resulting in a p olyhedr al cell. In such a c ase the shap e of the or iginal he xahedr al cell is preser ved (tha t is the o verall dimensions of the c ell sta y the same), but the c onverted c ell has mor e than the or iginal 6 fac es (see Figur e 6.70: A C onverted P olyhedr al C ell with P re- served H exahedr al C ell S hap e (p.798)). Figur e 6.70: A C onverted P olyhedr al C ell with P reser ved H exahedr al C ell S hap e Conversion pr oceeds in a sligh tly diff erent manner in b oundar y layers tha t are mo deled using thin wedge c ells.These c ells ar e dec omp osed in the plane of the b oundar y sur face, but not in the dir ection normal t o the sur face.The r esulting p olyhedr a will ther efore pr eser ve the thick ness of the or iginal wedge c ells ( Figur e 6.71: Treatmen t of Wedge B oundar y La yers (p.798)). In most c ases , the c ell c oun t in the new p olyhedr al b oundar y layer will b e lower than the or iginal b oundar y layer. Figur e 6.71: Treatmen t of Wedge B oundar y Layers To convert the en tire domain of y our mesh, click Make Polyhedr a in the Domain ribbon tab ( Mesh group b ox). Domain → Mesh → Make Polyhedr a The f ollowing is an e xample of the r esulting message pr inted in the c onsole: Setup conversion to polyhedra. Converting domain to polyhedra... Creating polyhedra zones. Processing face zones........... Processing cell zones... Building polyhedra mesh................... Optimizing polyhedra mesh..... >> Reordering domain using Reverse Cuthill-McKee method: zones, cells, faces, done. Bandwidth reduction = 1796/247 = 7.27 Done. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 798Reading and M anipula ting M eshesFigur e 6.72: The Or iginal Tetrahedr al M esh (p.799), the or iginal t etrahedr al mesh of a sec tion of a manif old, is c ompar ed t o Figur e 6.73: The C onverted P olyhedr al M esh (p.799), which is the r esulting mesh af ter the en tire domain is c onverted t o a p olyhedr a. Figur e 6.72: The Or iginal Tetrahedr al M esh Figur e 6.73: The C onverted P olyhedr al M esh Note tha t by default , the sur faces (tha t is, manif old z ones of t ype interior) will b e lost dur ing the conversion t o polyhedr a. If you w ould lik e to pr eser ve an y of these z ones (in or der t o utiliz e them f or postpr ocessing , for e xample), use the f ollowing t ext command pr ior t o the c onversion: mesh → polyhedra → options → preserve-interior-zones You will b e pr ompt ed t o en ter a str ing of char acters, and only those in terior sur faces with a name tha t includes the str ing y ou sp ecify will b e pr eser ved. In par allel, a new par titioning will b e stored af ter the c onversion, but b y default these new par titions will not b e made ac tive (tha t is, migr ated t o the c omput e-no des) as this r equir es signific ant additional memor y.The new par titions will b e sa ved with the c ase file and used aut oma tically when it is op ened in a new F luen t session; it is r ecommended tha t you then manually r eorder the domain pr ior t o calcu- lating (using the mesh/reorder/reorder-domain text command). If you w ant to use the new partitions in the cur rent Fluen t session, you should first ensur e tha t no mor e than half of the a vailable memor y of this sy stem is cur rently used , and then y ou c an manually migr ate the par titions (using the parallel/partition/use-stored-partitions text command) and r eorder. If you k now prior t o conversion tha t you will w ant to calcula te a solution in the same session (and y ou ha ve sufficien t memor y), you c an enable the f ollowing t ext command , so tha t the migr ation and r eordering is p erformed automa tically as par t of the c onversion: mesh → polyhedra → options → migrate-and-reorder? 799Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Converting the M esh t o a P olyhedr al M esh6.9.1.1. Limitations Some limita tions y ou will find with p olyhedr al meshes tha t you gener ally do not e xperienc e with other c ell t ypes include: •Meshes tha t alr eady contain p olyhedr al cells c annot b e converted. •Meshes with hanging no des/edges will not b e converted.This includes meshes tha t ha ve under gone hanging no de adaption (see Hanging N ode A daption in the Theor y Guide ), as w ell as C utCell meshes (gener ated b y Workbench or the meshing mo de of F luen t, or r esulting fr om the C utCell z one r emeshing metho d in the solution mo de of F luen t) and he xcore meshes (gener ated when using the Hex Core meshing scheme in GAMBIT or the Hexcore menu option in the meshing mo de of F luen t). •The following mesh manipula tion t ools ar e not a vailable f or p olyhedr al meshes: –the mesh/modify-zones/extrude-face-zone-delta text command –the mesh/modify-zones/extrude-face-zone-para text command –skewness smo othing –swapping •Meshes in which the domain has b een c onverted t o polyhedr al cells ar e not eligible f or adaption with the default hanging no de metho d, though the y can b e refined with the p olyhedr al unstr uctured mesh adaption (PUMA) metho d. For mor e inf ormation ab out adaption, see Adapting the M esh (p.2705 ). •A mesh tha t is c omp osed en tirely of p olyhedr al cells has limita tions when used in a d ynamic mesh pr oblem: it cannot under go d ynamic la yering, and the only r emeshing metho d available is C utCell z one r emeshing . Smoothing is allo wed f or p olyhedr al cells, and diffusion-based smo othing is r ecommended o ver spr ing- based smo othing (see Diffusion-B ased S moothing (p.1269 ) for details). The linear ly elastic solid smo othing metho d is not c ompa tible with p olyhedr al cells. •Since polyhedr al meshes c an ha ve a much higher r atio of no des t o cells then t et or he x meshes , the use of the no de-based gr adien t metho d ma y result in a signific ant incr ease in memor y consumption c ompar ed with other gr adien t metho ds. 6.9.2. Converting S kewed C ells t o Polyhedr a Another metho d of c ell agglomer ation is the sk ewness-based clust er appr oach. This t ype of c onversion is designed t o convert only par t of the domain. The objec tive is t o convert only sk ewed t etrahedr al cells ab ove a sp ecified c ell equiv olume sk ewness thr eshold in to polyhedr a. By converting the highly skewed t etrahedr al cells, the qualit y of the mesh c an b e impr oved signific antly. A diff erent algor ithm is used f or lo cal conversion. This algor ithm e valua tes each highly sk ewed t etra- hedr al cell and all of the sur rounding c ells, to selec t an edge on the highly sk ewed c ell tha t best matches cr iteria for c ell agglomer ation. Then all of the c ells tha t shar e this edge ar e combined in to a polyhedr al cell. During the pr ocess, the da ta is in terpolated fr om the or iginal c ells t o the r esultan t polyhedr a. 6.9.2.1. Limitations There ar e certain limita tions with this t ype of c onversion: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 800Reading and M anipula ting M eshes•The following mesh manipula tion t ools ar e not a vailable on p olyhedr al meshes: –the mesh/modify-zones/extrude-face-zone-delta text command –the mesh/modify-zones/extrude-face-zone-para text command –skewness smo othing –swapping will not aff ect polyhedr al cells •The p olyhedr al cells tha t result fr om the c onversion ar e not eligible f or adaption with the default hanging no de metho d, though the y can b e refined with the p olyhedr al unstr uctured mesh adaption (PUMA) metho d. For mor e inf ormation ab out adaption, see Adapting the M esh (p.2705 ). •Only t etrahedr al cells ar e converted, as all other c ells ar e sk ipped. •Meshes with hanging no des / edges will not b e converted.This includes meshes tha t ha ve under gone hanging no de adaption (see Hanging N ode A daption in the Theor y Guide ), as w ell as C utCell meshes (gener ated b y Workbench or the meshing mo de of F luen t, or r esulting fr om the C utCell z one r emeshing metho d in the solution mo de of F luen t) and he xcore meshes (gener ated when using the Hex Core meshing scheme in GAMBIT or the Hexcore menu option in the meshing mo de of F luen t). Note tha t if the mesh is a C utCell / he xcore mesh in which the tr ansitional c ells ha ve been c onverted t o polyhedr a, then it do es not ha ve hanging no des / edges and c an ther efore be converted. •The p olyhedr al cells tha t result fr om this c onversion ha ve the f ollowing limita tions with r egar d to the update metho ds a vailable f or d ynamic mesh pr oblems: –When applying d ynamic la yering t o a c ell z one , you c annot ha ve polyhedr al cells adjac ent to the mo ving face zone . –None of the r emeshing metho ds e xcept f or C utCell z one r emeshing will mo dify p olyhedr al cells. Note tha t smo othing is allo wed f or p olyhedr al cells, and diffusion-based smo othing is r ecommended over spr ing-based smo othing (see Diffusion-B ased S moothing (p.1269 ) for details). The linear ly elastic solid smo othing metho d is not c ompa tible with p olyhedr al cells. 6.9.3. Converting C ells with H anging N odes / E dges t o Polyhedr a ANSY S Fluen t provides a t ext command tha t allo ws you t o convert cells tha t ha ve hanging no des / edges in to polyhedr a. Such a c onversion ma y be done in or der t o pr event errors asso ciated with in terior walls (see Remo ving Hanging N odes/E dges (p.731)). Each of the c onverted p olyhedr a pr eser ve the shap e of the or iginal c ell (tha t is, the o verall dimensions of each c ell sta y the same), but the numb er of fac es asso ciated with each c ell incr eases (see Figur e 6.70: A C onverted P olyhedr al C ell with P reser ved Hexahedr al C ell S hap e (p.798) for an e xample). Such a c onversion ma y be helpful f or C utCell meshes (gener ated b y Workbench or the meshing mo de of F luen t, or r esulting fr om the C utCell z one remeshing metho d in the solution mo de of F luen t), as w ell as he xcore meshes (gener ated when using the Hex Core meshing scheme in GAMBIT or the Hexcore menu option in the meshing mo de of F luen t). You c ould also c onvert the c ells with hanging no des in a mesh tha t has under gone hanging no de adaption (see Adapting the M esh (p.2705 )), but y ou w ould need t o be sur e tha t no fur ther r efine- men t/coarsening of the mesh will b e nec essar y. To convert the c ells with hanging no des / edges , use the f ollowing t ext command: mesh → polyhedra → convert-hanging-nodes 801Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Converting the M esh t o a P olyhedr al M esh6.9.3.1. Limitations There ar e certain limita tions with this t ype of c onversion: •The following mesh manipula tion t ools ar e not a vailable on p olyhedr al meshes: –the mesh/modify-zones/extrude-face-zone-delta text command –the mesh/modify-zones/extrude-face-zone-para text command –skewness smo othing –swapping will not aff ect polyhedr al cells •The p olyhedr al cells tha t result fr om the c onversion ar e not eligible f or adaption with the default hanging no de metho d, though the y can b e refined with the p olyhedr al unstr uctured mesh adaption (PUMA) metho d. For mor e inf ormation ab out adaption, see Adapting the M esh (p.2705 ). •The p olyhedr al cells tha t result fr om this c onversion ha ve the f ollowing limita tions with r egar d to the update metho ds a vailable f or d ynamic mesh pr oblems: –When applying d ynamic la yering t o a c ell z one , you c annot ha ve polyhedr al cells adjac ent to the mo ving face zone . –None of the r emeshing metho ds e xcept f or C utCell z one r emeshing will mo dify p olyhedr al cells. Note tha t smo othing is allo wed f or p olyhedr al cells, and diffusion-based smo othing is r ecommended over spr ing-based smo othing (see Diffusion-B ased S moothing (p.1269 ) for details). The linear ly elastic solid smo othing metho d is not c ompa tible with p olyhedr al cells. 6.10. Modifying the M esh There ar e se veral w ays in which y ou c an mo dify or manipula te the mesh af ter it has b een r ead in to ANSY S Fluen t.You c an sc ale or tr ansla te the mesh, copy, mer ge, or separ ate zones , create or slit p eri- odic z ones , fuse b oundar ies, and smo oth and sw ap fac es. Metho ds for par titioning meshes t o be used in a par allel solv er ar e discussed in Mesh P artitioning and L oad B alancing (p.3067 ). Imp ortant Whene ver y ou mo dify the mesh, you should b e sur e to sa ve a new c ase file (and a da ta file, if da ta e xists). If you ha ve old da ta files tha t you w ould lik e to be able t o read in again, be sur e to retain the or iginal c ase file as w ell, as the da ta in the old da ta files ma y not c or- respond t o the new c ase file . Information ab out mesh manipula tion is pr ovided in the f ollowing sec tions: 6.10.1. Merging Z ones 6.10.2. Separ ating Z ones 6.10.3. Fusing F ace Zones 6.10.4. Creating P eriodic Z ones and In terfaces 6.10.5. Slitting P eriodic Z ones 6.10.6. Slitting F ace Zones 6.10.7. Orienting F ace Zones 6.10.8. Extruding F ace Zones Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 802Reading and M anipula ting M eshes6.10.9. Replacing , Deleting , Deactivating , and A ctivating Z ones 6.10.10. Copying C ell Z ones 6.10.11. Replacing the M esh 6.10.12. Managing A djac ent Zones 6.10.13. Reordering the D omain 6.10.14. Scaling the M esh 6.10.15. Transla ting the M esh 6.10.16. Rotating the M esh 6.10.17. Impr oving the M esh b y Smoothing and S wapping 6.10.1. Merging Z ones To simplify the solution pr ocess, you ma y want to mer ge z ones . Merging z ones in volves c ombining multiple z ones of similar t ype in to a single z one . Setting b oundar y conditions and p ostpr ocessing ma y be easier af ter y ou ha ve mer ged similar z ones . Zone mer ging is p erformed in the Merge Z ones D ialog Box (p.3850 ) (Figur e 6.74: The M erge Z ones Dialog Box (p.803)). Domain → Zones → Combine → Merge... Figur e 6.74: The M erge Z ones D ialo g Box 6.10.1.1. When t o Mer ge Z ones ANSY S Fluen t allo ws you t o mer ge z ones of similar t ype in to a single z one .This is not nec essar y unless the numb er of z ones b ecomes pr ohibitiv e to efficien t setup or p ostpr ocessing of the numer ical ana- lysis. For e xample , setting the same b oundar y condition par amet ers f or a lar ge numb er of z ones c an be time-c onsuming and ma y introduce inc onsist encies . In addition, the p ostpr ocessing of the da ta often in volves sur faces gener ated using the z ones . A lar ge numb er of z ones of ten tr ansla tes in to a large numb er of sur faces tha t must b e selec ted f or the v arious displa y options , such as c olor c ontouring. Fortuna tely, sur faces c an also b e mer ged (see Grouping , Editing , Renaming , and D eleting Sur- faces (p.2755 )), minimizing the nega tive impac t of a lar ge numb er of z ones on p ostpr ocessing efficienc y. Although mer ging z ones c an b e helpful, ther e ma y be cases wher e you will w ant to retain a lar ger numb er of z ones . Since the mer ging pr ocess is not fully r eversible , a lar ger numb er of z ones pr ovides mor e fle xibilit y in imp osing b oundar y conditions . Although a lar ge numb er of z ones c an mak e selec tion 803Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modifying the M eshof sur faces for displa y tedious , it c an also pr ovide mor e choic es for render ing the mesh and the flo w- field solution. For instanc e, it c an b e difficult t o render an in ternal flo w-field solution. If the out er domain is c omp osed of se veral zones , the meshes of subsets of these z ones c an b e plott ed along with the solution t o pr ovide the r elationship b etween the geometr y and solution field . Merging z ones may also ad versely aff ect dynamic z ones and mesh in terfaces. 6.10.1.2. Using the Mer ge Z ones D ialo g Box The pr ocedur e for mer ging multiple z ones of the same t ype in to a single z one is as f ollows: 1.Selec t the z one t ype in the Multiple Types list. This list c ontains all the z one t ypes for which ther e are multiple z ones .When y ou cho ose a t ype from this list , the c orresponding z ones will app ear in the Zones of Type list. 2.Selec t two or mor e zones in the Zones of Type list. 3.Click the Merge butt on t o mer ge the selec ted z ones . Note tha t if y our c ase file has d ynamic z ones or mesh in terfaces, the Warning dialo g box will op en b efore the mer ge is initia ted, allo wing y ou t o sp ecify whether y ou w ant to delet e such z ones or in terfaces first (see Warning D ialog Box (p.3960 ) for details). Imp ortant Rememb er to sa ve a new c ase file (and a da ta file , if da ta e xists). 6.10.2. Separ ating Z ones Upon r eading a mesh file , ANSY S Fluen t aut oma tically p erforms z one separ ations in t wo conditions . If a fac e zone is a ttached t o multiple c ells z ones in the pr eprocessor , the fac e zone will b e separ ated so that each one is a ttached t o only one c ell z one . Further mor e, if y ou ha ve defined an in ternal fac e as a wall t ype, an additional shado w w all z one will b e gener ated (f or e xample , for a w all named baffle , a shado w w all z one named baffle-shado w will b e gener ated). There ar e se veral metho ds a vailable in ANSY S Fluen t tha t allo w you t o manually separ ate a single fac e or c ell z one in to multiple z ones of the same t ype. If your mesh c ontains a z one tha t you w ant to br eak up in to smaller p ortions , you c an mak e use of these f eatures. For e xample , if y ou cr eated a single w all zone when gener ating the mesh f or a duc t, but y ou w ant to sp ecify diff erent temp eratures on sp ecific portions of the w all, you will need t o br eak tha t wall z one in to two or mor e wall z ones . If you plan t o solv e a pr oblem using the sliding mesh mo del or multiple r eference frames , but y ou f orgot t o cr eate different fluid z ones f or the r egions mo ving a t diff erent sp eeds , you will need t o separ ate the fluid zone in to two or mor e fluid z ones . Imp ortant •After p erforming an y of these separ ations , you should sa ve a new c ase file . If data exists , it is automa tically assigned t o the pr oper zones when separ ation o ccurs , so y ou should also wr ite a new da ta file .The old da ta cannot b e read on t op of the c ase file in which the z ones ha ve changed . •The maximum numb er of z ones in to which y ou c an separ ate an y one fac e zone or c ell z one is 32. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 804Reading and M anipula ting M eshesThere ar e four w ays to separ ate fac e zones and t wo ways to separ ate cell z ones .The fac e separ ation metho ds will b e descr ibed first , followed b y the c ell separ ation t ools. Slitting (dec oupling) of p eriodic zones is discussed in Slitting P eriodic Z ones (p.812). Note tha t all of the separ ation metho ds allo w you t o report the r esult of the separ ation b efore you commit t o performing it. 6.10.2.1. Separ ating F ace Zones For mor e inf ormation, see the f ollowing sec tions: 6.10.2.1.1. Metho ds for Separ ating F ace Zones 6.10.2.1.2. Inputs f or Separ ating F ace Zones 6.10.2.1.1. Metho ds for S epar ating F ace Zones For geometr ies with shar p corners , it is of ten easy t o separ ate fac e zones based on signific ant angle . Faces with nor mal v ectors tha t diff er b y an angle gr eater than or equal t o the sp ecified signific ant angle will b e plac ed in diff erent zones . For e xample , if y our mesh c onsists of a cub e, and all 6 sides of the cub e ar e in a single w all z one , you w ould sp ecify a signific ant angle of 89°. Since the nor mal vector for each cub e side diff ers b y 90° fr om the nor mals of its adjac ent sides , each of the 6 sides will b e plac ed in a diff erent wall z one . If you ha ve a small fac e zone and w ould lik e to put each fac e in the z one in to its o wn z one , you c an do so b y separ ating the fac es based on fac e. Each individual fac e (tr iangle , quad , or p olygon) will be separ ated in to diff erent zones . You c an also separ ate fac e zones based on c ell r egist ers. For e xample , you c an mar k cells based on their lo cation in the domain (r egion r egist er), their b oundar y closeness (b oundar y regist er), field values of some v ariable , or an y of the c ell mar king metho ds discussed in Using C ell R egist ers (p.2758 ). When y ou sp ecify which r egist er is t o be used f or the separ ation of the fac e zone , all fac es of c ells that are mar ked will b e plac ed in to a new fac e zone . Finally , you c an separ ate fac e zones based on c ontiguous r egions . For e xample , when y ou use coupled w all b oundar y conditions y ou need the fac es on the z one t o ha ve a c onsist ent orientation. Consist ent orientation c an only b e guar anteed on c ontiguous r egions , so y ou ma y need t o separ ate face zones t o allo w pr oper b oundar y condition sp ecific ation. 6.10.2.1.2. Inputs for S epar ating F ace Zones To br eak up a fac e zone based on angle , face, cell r egist er mar k, or r egion, use the Separ ate Face Zones D ialog Box (p.3915 ) (Figur e 6.75: The S epar ate Face Zones D ialog Box (p.806)). Domain → Zones → Separ ate → Faces... 805Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modifying the M eshFigur e 6.75: The S epar ate Face Zones D ialo g Box Imp ortant If you ar e planning t o separ ate fac e zones , you should do so b efore performing an y ad- aptions using the (default) hanging no de adaption metho d. Face zones tha t contain hanging no des c annot b e separ ated. The st eps f or separ ating fac es ar e as f ollows: 1.Selec t the separ ation metho d (Angle ,Face,Mark, or Region ) under Options . 2.Specify the fac e zone t o be separ ated in the Zones list. 3.If you ar e separ ating b y fac e or r egion, skip to the ne xt step. Other wise , do one of the f ollowing: •If you ar e separ ating fac es b y angle , specify the signific ant angle in the Angle field . •If you ar e separ ating fac es b y mar k, selec t the c ell regist er to be used in the Regist ers list. 4.(optional) To check wha t the r esult of the separ ation will b e before you ac tually separ ate the fac e zone , click the Rep ort butt on.The r eport will lo ok lik e the f ollowing e xample: 45 faces in contiguous region 0 30 faces in contiguous region 1 11 faces in contiguous region 2 14 faces in contiguous region 3 Separates zone 4 into 4 zone(s). 5.To separ ate the fac e zone , click the Separ ate butt on. A report will b e pr inted in the c onsole lik e the following e xample: 45 faces in contiguous region 0 30 faces in contiguous region 1 11 faces in contiguous region 2 14 faces in contiguous region 3 Separates zone 4 into 4 zone(s). Updating new zone information ... created new zone wall-4:001 from wall-4 created new zone wall-4:002 from wall-4 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 806Reading and M anipula ting M eshes created new zone wall-4:010 from wall-4 done. Imp ortant When y ou separ ate the fac e zone b y cell r egist er mar k, you ma y sometimes find tha t a face of a c orner c ell will b e plac ed in the wr ong fac e zone .You c an usually c orrect this problem b y performing an additional separ ation, based on angle , to mo ve the off ending face to a new z one .You c an then mer ge this new z one with the z one in which y ou w ant the fac e to be plac ed, as descr ibed in Merging Z ones (p.803). 6.10.2.2. Separ ating C ell Z ones For mor e inf ormation, see the f ollowing sec tions: 6.10.2.2.1. Metho ds for Separ ating C ell Z ones 6.10.2.2.2. Inputs f or Separ ating C ell Z ones 6.10.2.2.1. Metho ds for S epar ating C ell Z ones If you ha ve two or mor e enclosed c ell r egions shar ing in ternal b oundar ies (as sho wn in Figur e 6.76: Cell Zone S epar ation B ased on R egion (p.807)), but all of the c ells ar e contained in a single c ell z one , you can separ ate the c ells in to distinc t zones using the separ ation-b y-region metho d. Note tha t if the shar ed in ternal b oundar y is of t ype interior, you must change it t o another double-sided fac e zone type (fan,radia tor, and so on) pr ior t o performing the separ ation. Figur e 6.76: Cell Z one S epar ation B ased on Region You c an also separ ate cell z ones based on the mar ks st ored in c ell r egist ers.You c an mar k cells using any of the metho ds discussed in Using C ell R egist ers (p.2758 ) (for e xample , you c an mar k cells with a certain field v alue r ange or c ells inside or outside a sp ecified r egion). When y ou sp ecify which r e- gister is t o be used f or the separ ation of the c ell z one , cells tha t are mar ked will b e plac ed in to a new c ell z one . 6.10.2.2.2. Inputs for S epar ating C ell Z ones To br eak up a c ell z one based on r egion or c ell r egist er mar k, use the Separ ate Cell Z ones D ialog Box (p.3914 ) (Figur e 6.77: The S epar ate Cell Z ones D ialog Box (p.808)). Domain → Zones → Separ ate → Cells ... 807Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modifying the M eshFigur e 6.77: The S epar ate Cell Z ones D ialo g Box Imp ortant If you ar e planning t o separ ate cell z ones , you should do so b efore performing an y adap- tions using the (default) hanging no de adaption metho d. Cell z ones tha t contain hanging nodes c annot b e separ ated. The st eps f or separ ating c ells ar e as f ollows: 1.Selec t the separ ation metho d (Mark or Region ) under Options . 2.Specify the c ell z one t o be separ ated in the Zones list. 3.If you ar e separ ating c ells b y mar k, selec t the c ell regist er to be used in the Regist ers list. 4.(optional) To check wha t the r esult of the separ ation will b e before you ac tually separ ate the c ell z one , click the Rep ort butt on.The r eport will lo ok lik e this: Separates zone 14 into two zones, with 1275 and 32 cells. 5.To separ ate the c ell z one , click the Separ ate butt on. ANSY S Fluen t will pr int the f ollowing inf ormation: Separates zone 14 into two zones, with 1275 and 32 cells. No faces marked on thread, 2 No faces marked on thread, 3 No faces marked on thread, 1 No faces marked on thread, 5 No faces marked on thread, 7 No faces marked on thread, 8 No faces marked on thread, 9 No faces marked on thread, 61 Separates zone 62 into two zones, with 1763 and 58 faces. All faces marked on thread, 4 No faces marked on thread, 66 Moved 32 cells from cell zone 14 to zone 10 Updating new zone information ... created new zone interior-4:010 from interior-4 created new zone interior-6:009 from interior-6 created new zone fluid-14:008 from fluid-14 done. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 808Reading and M anipula ting M eshesAs sho wn in the e xample ab ove, separ ation of a c ell z one will of ten r esult in the separ ation of fac e zones as w ell.When y ou separ ate by mar k, faces of c ells tha t are mo ved t o a new z one will b e plac ed in a new fac e zone .When y ou separ ate by region, faces of c ells tha t are mo ved t o a new z one will not nec essar ily b e plac ed in a new fac e zone . If you find tha t an y fac es ar e plac ed inc orrectly, see the c ommen t ab ove, at the end of the inputs for fac e zone separ ation. 6.10.3. Fusing F ace Zones The fac e-fusing utilit y is a c onvenien t feature tha t can b e used t o fuse b oundar ies (and mer ge duplic ate nodes and fac es) cr eated b y assembling multiple mesh r egions .When the domain is divided in to subdomains and the mesh is gener ated separ ately f or each sub domain, you will c ombine the sub do- mains in to a single file b efore reading the mesh in to Fluen t. For details , see Reading M ultiple Mesh/C ase/D ata Files (p.733).This situa tion c ould ar ise if y ou gener ate each blo ck of a multiblo ck mesh separ ately and sa ve it t o a separ ate mesh file . Another p ossible sc enar io is tha t you decided , dur ing mesh gener ation, to sa ve the mesh f or each par t of a c omplic ated geometr y as a separ ate par t file . (Note tha t the mesh no de lo cations need not b e iden tical at the b oundar ies wher e two sub domains meet; see Non-C onformal M eshes (p.741) for details .) The Fuse F ace Zones dialo g box (Figur e 6.78: The F use F ace Zones D ialog Box (p.809)) allo ws you t o mer ge the duplic ate no des and delet e these ar tificial in ternal b oundar ies. Domain → Zones → Combine → Fuse ... Figur e 6.78: The F use F ace Zones D ialo g Box The b oundar ies on which the duplic ate no des lie ar e assigned z one ID numb ers (just lik e an y other boundar y) when the mesh files ar e combined , as descr ibed in Reading M ultiple M esh/C ase/D ata Files (p.733).You need t o keep tr ack of the z one ID numb ers when tmerge or the meshing mo de of Fluen t reports its pr ogress or , after the c omplet e mesh is r ead in, displa y all b oundar y mesh z ones and use the mouse-pr obe butt on t o det ermine the z one names (see Controlling the M ouse B utton F unc- 809Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modifying the M eshtions (p.2833 ) for inf ormation ab out the mouse butt on func tions). Alternatively, you c an sp ecify a name for the fused z one . 6.10.3.1. Inputs for F using F ace Zones The st eps f or fusing fac e zones ar e as f ollows: 1.Selec t the z ones t o be fused in the Zones list. Imp ortant When using the F use F ace Zone utilit y, each of the selec ted fac e zones must b e fused in its en tirety with another fac e zone ha ving the same c onnec tivit y. Partial fusing of face zones is not supp orted. 2.(Optional) I f you w ould lik e to sp ecify a name f or the fused z one r ather than use an aut oma tically gener- ated name (f or instanc e, to pr eser ve the or iginal name of one of the fac e zones), disable Use default name f or ne w fused z one and en ter the desir ed name . 3.Click the Fuse butt on t o fuse the selec ted z ones . If all of the appr opriate fac es do not get fused using the default Toler anc e, you should incr ease it and a ttempt t o fuse the z ones again. (This t oler ance is the same as the ma tching t oler ance discussed in Creating P eriodic Z ones and In terfaces (p.811).) The Toler anc e should not e xceed 0.5, or y ou ma y fuse the wr ong no des. You c an also fuse z ones using the mesh/modify-zones/fuse-face-zones text command , as shown in the f ollowing e xample . /mesh/modify-zones > fuse-face-zones () Zone to fuse(1) [()] w1.top Zone to fuse(2) [()] w3 Zone to fuse(3) [()] [Enter] Choose from list (automatic w3 w1.top) or pick your own Enter the fused zone name: [automatic] w3 Name of zone 14 is changed into w3. Fused list of zones successfully. Imp ortant Rememb er to sa ve a new c ase file (and a da ta file , if da ta e xists) af ter fusing fac es. 6.10.3.1.1. Fusing Z ones on Br anch C uts Meshes imp orted fr om str uctured mesh gener ators or solv ers (such as FL UENT 4) c an of ten b e O- type or C-t ype meshes with a r eentrant branch cut wher e coinciden t duplic ate no des lie on a p eri- odic b oundar y. Since ANSY S Fluen t uses an unstr uctured mesh r epresen tation, ther e is no r eason t o Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 810Reading and M anipula ting M eshesretain this ar tificial in ternal b oundar y. (You c an pr eser ve these p eriodic b oundar ies and the solution algor ithm will solv e the pr oblem with p eriodic b oundar y conditions .) To fuse this p eriodic z one with itself , you must first slit the p eriodic z one , as descr ibed in Slitting Periodic Z ones (p.812).This will cr eate two symmetr y zones tha t you c an fuse using the pr ocedur e above. Note tha t if y ou need t o fuse p ortions of a non-p eriodic z one with itself , you must use the mesh/modify-zones/fuse-face-zones text command . mesh → modify-zones → fuse-face-zones This c ommand will pr ompt y ou f or the name or ID of each z one t o be fused . (You will en ter the same z one t wice.) To change the no de t oler ance, use the mesh/modify-zones/matching- tolerance text command . 6.10.4. Creating P eriodic Z ones and In terfaces ANSY S Fluen t allo ws you t o assign p eriodicit y to your mesh b y coupling a pair of fac e zones . If the two zones ar e conformal (tha t is, have iden tical no de and fac e distr ibutions), then y ou c an c ombine them in a single b oundar y zone of t ype periodic. If the t wo zones ar e not iden tical at the b oundar ies within a sp ecified t oler ance, then y ou c an change them b oth t o be of t ype interface and include them in a non-c onformal mesh in terface tha t is p eriodic. Imp ortant Rememb er to sa ve a new c ase file (and a da ta file , if da ta e xists) af ter cr eating or slitting a periodic b oundar y. To cr eate a p eriodic b oundar y or in terface, you c an use the f ollowing t ext command . mesh → modify-zones → create-periodic-interface You c an sp ecify whether the fac e zones tha t mak e up the p eriodic pair ar e conformal or not , or let Fluen t aut oma tically handle this decision (in which c ase a c onformal pair ing will b e used if p ossible). Next, you must sp ecify the b oundar y zones , using either their full names or just their IDs; not e tha t the or der in which y ou sp ecify them is not signific ant.Then y ou must indic ate if the y are rotationally or tr ansla tionally p eriodic, and define the axis and off set. For pair ings tha t are non-c onformal (or c ould potentially b e, when using the aut oma tic metho d), you must pr ovide a name f or the p eriodic mesh interface tha t will / ma y be created.The f ollowing is an e xample this t ext command: /mesh/modify-zones> create-periodic-interface Periodic interface methods: auto, conformal, nonconformal Enter method [auto] Periodic zone [()] 10 Shadow zone [()] 9 Rotational periodic? (if no, translational) [yes] Current axis origin is (0 0 0) Enter a new axis origin? [no] Current axis direction is (0 0 1) Enter a new axis direction? [no] 811Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modifying the M eshAuto detect offset? [yes] Create periodic zone? [yes] Periodic interface name [] per-zone Create matching interface? [no] zone 9 deleted Created conformal periodic interface. When a ttempting t o cr eate a c onformal p eriodic b oundar y, Fluen t will check t o see if the fac es on the selec ted z ones “match” (tha t is, whether or not the no des on c orresponding fac es ar e coinciden t).The matching t oler ance for a fac e is a fr action of the minimum edge length of the fac e. If the cr eation of a conformal p eriodic b oundar y fails , you c an change the ma tching t oler ance using the f ollowing t ext command .The t oler ance should not e xceed 0.5, or y ou ma y ma tch up the p eriodic z ones inc orrectly and c orrupt the mesh. mesh → modify-zones → matching-tolerance Note tha t when using the densit y-based solv er, you c an sp ecify a pr essur e jump f or a c onformal p eri- odic z one; for details , see Periodic F lows (p.1206 ). For mor e inf ormation ab out non-c onformal p eriodic b oundar ies and an alt ernate way to cr eate them, see Non-C onformal M eshes (p.741) and Using a N on-C onformal M esh in ANSY S Fluen t (p.756), respect- ively. 6.10.5. Slitting P eriodic Z ones If you w ant to dec ouple the z ones in a p eriodic pair , you c an use the mesh/modify-zones/slit- periodic text command . mesh → modify-zones → slit-periodic You will sp ecify the p eriodic z one’s name or ID , and F luen t will dec ouple the t wo zones in the pair (the p eriodic z one and its shado w) and change them t o two symmetr y zones: /mesh/modify-zones> slit-periodic Periodic zone [()] periodic-1 Slit periodic zone? [yes] yes Slit periodic zone. 6.10.6. Slitting F ace Zones The fac e-zone slitting f eature has t wo uses: •You c an slit a single b oundar y zone of an y double-sided t ype (tha t is, any boundar y zone tha t has c ells on both sides of it) in to two distinc t zones . •You c an slit a c oupled w all z one in to two distinc t, unc oupled w all z ones . When y ou slit a fac e zone , Fluen t will duplic ate all fac es and no des, except those no des tha t are lo cated at the ends (2D) or edges (3D) of the z one . One set of no des and fac es will b elong t o one of the r es- ulting b oundar y zones and the other set will b elong t o the other z one .The only ill eff ect of the shar ed Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 812Reading and M anipula ting M eshesnodes a t each end is tha t you ma y see some inaccur acies a t those p oints when y ou gr aphic ally displa y solution da ta with a slit b oundar y. (Note tha t if y ou adapt the b oundar y after slitting , you will not b e able t o fuse the b oundar ies back t ogether again.) Before you c an slit , you first need t o selec t the z one in the Boundar y Condition task page and change the Type to wall. Upon changing the Type to wall, another shado w zone will b e created (tha t is, if the or iginal z one is c alled rad-outlet , another z one c alled rad-outlet-shado w will b e created). Then you c an apply the mesh/modify-zones/slit-face-zone text command on either of the w alls (tha t is,rad-outlet or rad-outlet-shado w) to separ ate them in to two distinc t walls. Imp ortant When a w all and w all-shado w pair is cr eated b y slitting a fac e zone , the w all will inher it the zone id numb er and fac e or ientation of the or iginal z one . A new z one id numb er will b e created and assigned t o the w all-shado w. For e xample , the outlet of the r adia tor in an under hood applic ation is t ypic ally of interior type (tha t is, has c ells on b oth sides). If you k now the mass flo w rate thr ough this z one (either fr om other CFD models or fr om t est da ta) and w ant to apply it as a b oundar y condition a t the r adia tor outlet , you first need t o slit the r adia tor outlet. To be able t o slit it , selec t wall from the Type drop-do wn list in the Boundar y Conditions task page f or this outlet. It will cr eate a w all and a shado w.Then y ou c an use the TUI c ommand (mesh/modify-zones/slit-face-zone ) to slit them. After it is slit , two addi- tional w alls will b e created, one facing one side of the outlet and another facing the other .Then y ou can selec t the appr opriate wall and change the Type to mass-flo w-inlet and sp ecify the mass flo w rate using the Mass-F low Inlet D ialog Box (p.3502 ).There is no option of mass-flo w-inlet without first slitting it. Imp ortant You should not c onfuse “slitting ” a fac e zone with “separ ating ” a fac e zone .When y ou slit a fac e zone , additional fac es and no des ar e created and plac ed in a new z one .When y ou separ ate a fac e zone , a new z one will b e created, but no new fac es or no des ar e created; the e xisting fac es and no des ar e simply r edistr ibut ed among the z ones . 6.10.6.1. Inputs for Slitting F ace Zones If you w ant to slit a fac e zone , you c an use the mesh/modify-zones/slit-face-zone text command . mesh → modify-zones → slit-face-zone You will sp ecify the fac e zone’s name or ID , and F luen t will r eplac e the z one with t wo zones: /mesh/modify-zones > slit-face-zone Face zone id/name [] wall-4 zone 4 deleted 813Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modifying the M esh face zone 4 created face zone 10 created Imp ortant Rememb er to sa ve a new c ase file (and a da ta file , if da ta e xists) af ter slitting fac es. 6.10.7. Orienting F ace Zones The fac es of a b oundar y fac e zone (which ha ve cells only on one side) ar e or iented such tha t the nor mals are all p ointing in one dir ection. However, for in ternal fac e zones (which ha ve cells on b oth sides), the normals ar e allo wed t o point in either dir ection. To or ient them so tha t the y all p oint in one dir ection, you c an use the f ollowing TUI c ommand: mesh → modify-zones → orient-face-zone Having all of the nor mals or iented in one dir ection is needed f or some b oundar y condition t ypes. For example , the fan boundar y condition t ype det ermines the flo w dir ection based on its nor mals . If some of the nor mals ar e pointing in one dir ection and some in the other , the c orrect flo w or ientation c annot be det ermined , which leads t o inc orrect results . 6.10.8. Extruding F ace Zones The abilit y to extrude a b oundar y fac e zone allo ws you t o extend the solution domain without ha ving to exit F luen t. A typic al applic ation of the e xtrusion c apabilit y is t o extend the solution domain when recircula ting flo w is impinging on a flo w outlet. The cur rent extrusion c apabilit y creates pr isma tic or hexahedr al la yers based on the shap e of the fac e and nor mal v ectors c omput ed b y averaging the fac e normals t o the fac e zone’s no des.You c an define the e xtrusion pr ocess b y sp ecifying a list of displac e- men ts (in SI units) or b y sp ecifying a t otal distanc e (in SI units) and par ametr ic coordina tes. Imp ortant •Note tha t extrusion is not p ossible fr om b oundar y fac e zones tha t ha ve hanging no des. •Extruding fac e zones is not allo wed on p olygonal fac e zones . •Extruding fac e zones is only allo wed in the 3D v ersion of ANSY S Fluen t. 6.10.8.1. Specifying E xtrusion b y Displac ement D istanc es You c an sp ecify the e xtrusion b y en tering a list of displac emen t distanc es (in SI units) using the mesh/modify-zones/extrude-face-zone-delta text command . mesh → modify-zones → extrude-face-zone-delta Note This t ext command is not a vailable in the par allel v ersion of ANSY S Fluen t. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 814Reading and M anipula ting M eshesYou will b e pr ompt ed f or the b oundar y fac e zone ID or name and a list of displac emen t distanc es. 6.10.8.2. Specifying E xtrusion b y Parametric C oordinat es You c an sp ecify the e xtrusion b y sp ecifying a distanc e (in SI units) and par ametr ic coordina tes using the mesh/modify-zones/extrude-face-zone-para text command . mesh → modify-zones → extrude-face-zone-para Note This t ext command is not a vailable in the par allel v ersion of ANSY S Fluen t. You will b e pr ompt ed f or the b oundar y fac e zone ID or name , a total distanc e, and a list of par ametr ic coordina tes.The list of par ametr ic coordina tes should b egin with 0.0 and end with 1.0. For e xample , the f ollowing list of par ametr ic coordina tes w ould cr eate two equally spac ed e xtrusion la yers: 0.0, 0.5, 1.0. 6.10.9. Replacing , Deleting , Deac tivating , and A ctivating Z ones ANSY S Fluen t allo ws you t o app end or r eplac e an e xisting c ell z one in the mesh. You c an also p erman- ently delet e a c ell z one and all asso ciated fac e zones , or t emp orarily deac tivate and ac tivate zones from y our ANSY S Fluen t case. 6.10.9.1. Replacing Z ones This f eature allo ws you t o replac e a small r egion of a c omputa tional domain with a new r egion of different mesh qualit y.This func tionalit y will b e requir ed wher e you ma y want to mak e changes t o the geometr y or mesh qualit y for an y par t of the domain. This abilit y of ANSY S Fluen t will sa ve you time , sinc e you c an mo dify only the r equir ed par t of the domain without r emeshing the whole domain every time . The r eplac emen t mesh must b e pr epar ed in ad vance, with the f ollowing c onsider ations: •The r eplac emen t mesh must c ontain a single c ell z one . •The c ell z one in the r eplac emen t mesh must b e of the same z one t ype as the z one tha t is b eing r eplac ed. •If the b oundar ies of the r eplac emen t mesh will f orm a non-c onformal in terface with e xisting z ones (tha t is, zones tha t are not r eplac ed in the e xisting mesh), these b oundar ies should b e based on the same geometr y as the e xisting z ones . If ther e are shar p features (f or e xample , 90-degr ee angles) or cur vature in the mesh, it is esp ecially imp ortant tha t both sides of the in terface closely f ollow tha t feature. •The r eplac emen t cell z one do es not need t o ha ve the same name as the e xisting z one b eing r eplac ed. •When naming the b oundar y zones of the r eplac emen t cell z one , not e tha t boundar y conditions will b e automa tically tr ansf erred fr om the e xisting c ell z one based on name . All boundar ies of the r eplac emen t cell z one tha t ha ve unique names will b e assigned the default b oundar y condition f or tha t zone t ype. Replacing a z one is p erformed using the Replac e Cell Z one D ialog Box (p.3905 ) (Figur e 6.79: The R eplac e Cell Z one D ialog Box (p.816)). 815Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modifying the M eshDomain → Zones → Replac e Zone ... Figur e 6.79: The Replac e Cell Z one D ialo g Box To replac e a z one , do the f ollowing: 1.Click Browse... and selec t the new or mo dified mesh c ontaining the c ell z one tha t will r eplac e one of the c ell z ones in the cur rent mesh. The name of the c ell z one in the r eplac ement mesh will b e displa yed in the Replac e with list . 2.Under Existing Z ones , selec t the z one y ou w ant to replac e. 3.Under Replac e with , selec t the z one fr om the r eplac emen t mesh. 4.Enable/D isable Interpolate Data, if da ta alr eady exists . If the r eplac emen t cell z one is geometr ically different, then Interpolate Data can b e tur ned off t o pr event da ta in terpolation o ver the non-ma tching geometr ies. Imp ortant Disable Interpolate D ata if the z one b eing r eplac ed is par t of an o verset in terface. 5.Click Replac e to replac e the selec ted z one . 6.Set up the b oundar y conditions f or an y of the b oundar ies of the r eplac emen t mesh tha t do not shar e a name with one of the e xisting b oundar ies. 6.10.9.2. Deleting Z ones To permanen tly delet e zones , selec t them in the Delete Cell Z ones D ialog Box (p.3802 ) (Figur e 6.80: The Delete Cell Z ones D ialog Box (p.817)), and click Delet e. Domain → Zones → Delet e... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 816Reading and M anipula ting M eshesFigur e 6.80: The D elet e Cell Z ones D ialo g Box All of the c ells, faces, and no des asso ciated with the c ell z one will b e delet ed. If one of the fac es is of type interior and b orders another c ell z one , the fac e will aut oma tically b e changed t o a w all and will sta y attached t o the r emaining c ell z one . 6.10.9.3. Deac tivating Z ones To deac tivate zones , selec t them in the Deactivate Cell Z ones D ialog Box (p.3799 ) (Figur e 6.81: The Deactivate Cell Z ones D ialog Box (p.817)), and click Deac tivate. Domain → Zones → Deac tivate... Figur e 6.81: The D eac tivate Cell Z ones D ialo g Box 817Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modifying the M eshDeactivation will separ ate all r elevant interior fac e zones (tha t is, fan, interior, porous-jump , or r adia tor) into wall and w all-shado w pairs . Note When y ou deac tivate a z one using the Deac tivate Cell Z ones dialo g box, ANSY S Fluen t will remo ve the z one fr om the mesh and fr om all r elevant solv er lo ops. Imp ortant If a c ell z one c ontains mesh in terfaces it c annot b e deac tivated un til the solution has b een initializ ed. 6.10.9.4. Activating Z ones You c an r eactivate the z ones and r ecover the last da ta a vailable f or them using the Activate Cell Zones D ialog Box (p.3776 ) (Figur e 6.82: The A ctivate Cell Z ones D ialog Box (p.818)). Domain → Zones → Activate... Figur e 6.82: The A ctivate Cell Z ones D ialo g Box Note The Activate Cell Z ones dialo g box will only b e popula ted with z ones tha t were pr eviously deac tivated. After reactivation, you need t o mak e sur e tha t the b oundar y conditions f or the w all and w all-shado w pairs ar e restored c orrectly t o wha t you assigned b efore deac tivating the z ones . If you plan t o react- ivate them a t a la ter time , mak e sur e tha t the fac e zones tha t are separ ated dur ing deac tivation ar e not mo dified . Adaption, however, is supp orted. 6.10.10. Copying C ell Z ones You c an cr eate a c opy of a c ell z one tha t is off set fr om the or iginal either b y a tr ansla tional distanc e or a r otational angle . Note tha t in the c opied z one , the b ounding fac e zones ar e all c onverted t o walls, Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 818Reading and M anipula ting M eshesany existing c ell da ta is initializ ed t o a c onstan t value , and non-c onformal in terfaces and d ynamic zones ar e not c opied; other wise , the mo del settings ar e the same as in the or iginal z one . To copy a z one , use the f ollowing t ext command: mesh → modify-zones → copy-move-cell-zone You will then b e pr ompt ed t o en ter the ID of the z one y ou w ant to copy, and either the distanc e for transla tion in each of the ax es or the r otational angle , origin, and axis . Note tha t if y ou w ant the c opied z one t o be connec ted t o existing z ones , you must either fuse the boundar ies (as descr ibed in Fusing F ace Zones (p.809)) or set up a non-c onformal in terface (as descr ibed in Using a N on-C onformal M esh in ANSY S Fluen t (p.756)). 6.10.11. Replacing the M esh ANSY S Fluen t allo ws you t o replac e your mesh, so tha t you c an c ontinue t o run y our simula tion on a new mesh without ha ving t o manually c opy the c ase file settings or in terpolate the e xisting da ta. Re- placing the mesh globally ma y be helpful, for e xample , if y ou w ould lik e to perform a mesh r efinemen t stud y with a pr epar ed ser ies of meshes , or if y our r esults indic ate tha t your cur rent mesh is not of sufficien t qualit y. Note tha t the da ta in terpolation is done aut oma tically dur ing the r eplac emen t if da ta exists (tha t is, you ha ve initializ ed the flo w field or r un a c alcula tion). Global mesh r eplac emen t is p erformed b y click ing Replac e M esh... in the Domain ribbon tab Zones group b ox), which op ens the Selec t File dialo g box (Figur e 6.83: The S elec t File D ialog Box (p.819)). Figur e 6.83: The S elec t File D ialo g Box 819Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modifying the M esh6.10.11.1. Inputs for R eplacing the Mesh The st eps f or replacing the mesh using the Selec t File dialo g box (Figur e 6.83: The S elec t File D ialog Box (p.819)) are as f ollows: 1.Selec t the r eplac emen t mesh fr om the appr opriate folder . 2.By default , data is in terpolated b etween ma tching z one pairs (tha t is, between the z ones with the same names in b oth the cur rent mesh and the r eplac emen t mesh). You c an enable the Interpolate Data Across Z ones option if y ou w ant to interpolate da ta acr oss c ell z ones when r eplacing the mesh. This option is appr opriate when the ma tching z one pairs do not ha ve the same in terior z one b oundar ies. Note tha t global c onser vation of da ta is not enf orced when the Interpolate Data A cross Z ones option is enabled , so it should only b e used when absolut ely nec essar y. For b est da ta in terpolation, the z one boundar ies of the r eplac emen t mesh should b e coinciden t with those of the cur rent mesh. When r unning in par allel the r eplac emen t mesh gets par titioned such tha t ma tching c ells r eside on the same c omput e no de. In some c ases , diff erences in mesh r esolution c an c ause the mesh t o not b e able t o find its in terpolation c ell on the same c omput e no de dur ing in terpolation. Fluen t then aut oma tically enables Interpolate D ata A cross Z ones to ensur e succ essful da ta in terpolation across z ones , even if y ou ha ve not enabled the option. To avoid this b ehavior use the Scheme command:(rpsetvar 'dynamesh/replace-mesh/partition-per-zone? #t) . Note that using this c ommand c omes a t the e xpense of r equir ing additional r epar titioning st eps. 3.Click the OK butt on t o replac e the mesh. 6.10.11.2. Limitations The f ollowing limita tions apply when r eplacing meshes: •The b oundar y conditions of the z ones in the cur rent mesh ar e mapp ed on to the z ones with the same names in the r eplac emen t mesh, as descr ibed in Reading and Writing B oundar y Conditions (p.596). If your replac emen t mesh c ontains z ones f or which no ma tch is f ound , these z ones will ha ve the default b oundar y conditions f or tha t zone t ype. •The r eplac emen t mesh is e xpected t o be an ANSY S Fluen t mesh (.msh ) file .You c an selec t an ANSY S Fluen t case (.cas ) file inst ead, but b e aware tha t only the mesh inf ormation will b e used and all of the setup inf ormation asso ciated with tha t case file will b e ignor ed. •If you in tend t o selec t an ANSY S Fluen t case (.cas ) file as the r eplac emen t mesh, you must first delet e any defined non-c onformal mesh in terfaces in the c ase file (as descr ibed in Using a N on-C onformal M esh in ANSY S Fluen t (p.756)). •You should ensur e tha t the r eplac emen t mesh has the same mesh sc aling as y our cur rent mesh. The da ta interpolation will not w ork pr operly if the meshes ar e sc aled diff erently. 6.10.12. Managing A djac ent Zones In some c ases y ou ma y want to iden tify and displa y the fac e zones which ar e adjac ent to a c ell z one . You c an do this using the Adjac enc y dialo g box. Domain → Zones → Adjac enc y... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 820Reading and M anipula ting M eshesFigur e 6.84: The A djac enc y D ialo g Box Using the Adjac enc y dialo g box (Figur e 6.84: The A djac ency Dialog Box (p.821)) you c an also optionally rename z ones based on their adjac ency or with default names based on z one t ype.The st eps t o use the Adjac enc y dialo g box are: 1.Open the Adjac enc y dialo g box by click ing Adjac enc y... in the Domain ribbon tab ( Zones group b ox). 2.Selec t a z one under Cell Z one(s) to popula te the Adjac ent Face Zones list. You c an use the 'T oggle Tree View' ic on ( ) to gr oup the c ell z ones b y type. If the Multiple C ell Z ones option is disabled , only one cell z one c an b e selec ted a t a time . 3.Selec t the fac e zones y ou w ant to displa y in Adjac ent Face Zones and click the Displa y Face Zones butt on. 4.Enable Draw D efault M esh to op en the Mesh D ispla y dialo g box wher e you ma y cho ose t o displa y mesh zones .These will b e displa yed p ermanen tly while others will b e displa yed as cur rently selec ted in the Adjac ent Face Zones list. This is useful f or finding y our w ay thr ough a new and c omple x mesh. 5.Enable Rename F ace Zones if you w ant to rename or clean up some of the names tha t ma y cause c onfu- sion. See Renaming Z ones U sing the A djac ency Dialog Box (p.821) for mor e inf ormation. 6.10.12.1. Renaming Z ones Using the A djac enc y Dialo g Box You c an r ename selec ted z ones fr om the A djac ency dialo g box after enabling Rename F ace Zones . The f ollowing r enaming metho ds ar e available: Rename b y Adjac enc y app ends the name of the c ell z one t o the t ype of the adjac ent fac e zone . For e xample , if fluid is selec ted in the Cell Z one(s) and interior is selec ted in the Adjac ent Face Zones list, then r enaming b y adjac ency 821Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modifying the M eshproduces interior-fluid . If the name is alr eady in use , the or iginal z one ID is app ended in addition in order t o create a unique name . Note tha t it is b est if y ou a void using long c ell z one names . Rename t o D efault simply app ends the or iginal z one ID t o the z one t ype. Enable Abbr eviate Types to abbr eviate the z one type (for e xample ,vi for v elocity inlet ,int for in terior,ifc for in terface, and so on). Rename b y Wildc ard performs pa ttern ma tching of the selec ted z one names against the pa ttern in the From text box (with optional wildc ards) and r eplac es a ma tching substr ing with the lit eral str ing in the To text box.Wildcard char acters * and ? are interpreted as f ollows: •A * at the b eginning and/or end of the From pattern ma tches z ero or mor e char acters a t the b eginning and/or end of the z one name tha t are retained dur ing r enaming with the r est of the name r eplac ed by the To string. A * used an ywher e except a t the b eginning or end of the From pattern is not supp orted and may ha ve unpr edic table r esults . •A ? matches e xactly one char acter and is c onsider ed par t of the str ing t o be replac ed. Multiple ? char acters c an b e used t o ma tch substr ings of mor e than one char acter. For all of the r enaming metho ds, you c an enable Exclude C ustom N ames to exclude cust omiz ed names (those tha t do not c onform to a r ecogniz ed pa ttern or ma tch an y default names) fr om r enaming . This is a pr otective measur e so as not t o acciden tally destr oy your desir ed naming . Disabling this option will unc onditionally r ename all selec ted z ones acc ording t o the sp ecified r enaming metho d and cust omiz ed names will b e permanen tly lost. 6.10.13. Reor dering the D omain In a F luen t session tha t uses multiple pr ocesses , the mesh domain is aut oma tically r eordered when it is read, in or der t o incr ease memor y acc ess efficienc y.The r eordering uses the R everse C uthill-M cKee algor ithm [26] (p.4006 ), and is applied t o cells and fac es. A typic al output pr oduced dur ing the domain r eordering a t read is sho wn b elow: Building... mesh auto partitioning mesh by Metis (fast), distributing mesh parts..., faces..., nodes..., cells..., bandwidth reduction using Reverse Cuthill-McKee: 3875/150 = 25.8333 The band width is the maximum diff erence between neighb oring c ells in the z one—tha t is, if y ou numb ered each c ell in the z one list sequen tially and c ompar ed the diff erences b etween these indic es. 6.10.14. Scaling the M esh Internally , ANSY S Fluen t stores the c omputa tional mesh in met ers, the SI unit of length. When mesh information is r ead, it is assumed tha t the mesh w as gener ated in units of met ers. If your mesh w as created using a diff erent unit of length (inches , feet, centimet ers, and so on), you must sc ale the mesh to met ers.To do this , you c an selec t from a list of c ommon units t o convert the mesh or y ou c an Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 822Reading and M anipula ting M eshessupply y our o wn cust om sc ale fac tors. Each no de c oordina te will b e multiplied b y the c orresponding scale fac tor. Scaling c an also b e used t o change the ph ysical siz e of the mesh. For instanc e, you c ould str etch the mesh in the direction b y assigning a sc ale fac tor of 2 in the direction and 1 in the and directions . This w ould double the e xtent of the mesh in the direction. However, you should use anisotr opic scaling with c aution, sinc e it will change the asp ect ratios of the c ells in y our mesh. Imp ortant •If you plan t o sc ale the mesh in an y way, you should do so b efore you c omput e the view fac tors (as par t of an S2S r adia tion pr oblem), initializ e the flo w, or b egin c alcula tions . Any da ta tha t exists when y ou sc ale the mesh will b e invalid. •It is a go od pr actice to sc ale the mesh b efore setting up the c ase, esp ecially when y ou plan t o create mesh in terfaces or shell c onduc tion z ones . •Scaling the mesh mak es the gr aphics windo w [Out of D ate]. Right-click in the gr aphics windo w and selec t Refr esh D ispla y to up date the windo w. You ma y ha ve to click to see the objec t in the gr aphics windo w af ter r efreshing the dis- play. You will use the Scale M esh D ialog Box (p.3238 ) (Figur e 6.85: The Sc ale M esh D ialog Box (p.823)) to sc ale the mesh fr om a standar d unit of measur emen t or t o apply cust om sc aling fac tors. Setup → Gener al → Mesh → Scale... Figur e 6.85: The Sc ale M esh D ialo g Box 823Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modifying the M esh6.10.14.1. Using the Sc ale Mesh D ialo g Box The pr ocedur e for sc aling the mesh is as f ollows: 1.Use the c onversion fac tors pr ovided b y ANSY S Fluen t by selec ting Convert Units in the Scaling group box.Then indic ate the units used when cr eating the mesh b y selec ting the appr opriate abbr eviation f or met ers, centimet ers, millimet ers, inches , or f eet fr om the Mesh Was C reated In drop-do wn list. The Scaling F actors will aut oma tically b e set t o the c orrect values (f or e xample , 0.0254 met ers/inch). If you cr eated y our mesh using units other than those in the Mesh Was C reated In drop-do wn list, you c an selec t Specify Sc aling F actors and en ter v alues f or X,Y, and Z manually in the Scaling F actors group b ox (for e xample , the numb er of met ers p er y ard). 2.Click the Scale butt on.The Domain E xtents will b e up dated t o sho w the c orrect range in met ers. If you prefer to use y our or iginal unit of length dur ing the ANSY S Fluen t session, you c an follow the pr ocedur e descr ibed b elow to change the unit. 6.10.14.1.1. Changing the Unit of L ength As men tioned in S tep 2. of the pr evious sec tion, when y ou sc ale the mesh y ou do not change the units; you just c onvert the or iginal dimensions of y our mesh p oints fr om y our or iginal units t o met ers by multiplying each no de c oordina te by the sp ecified Scaling F actors. If you w ant to work in y our original units , inst ead of in met ers, you c an mak e a selec tion fr om the View L ength U nit In drop- down list. This up dates the Domain E xtents to sho w the r ange in y our or iginal units and aut oma t- ically changes the length unit in the Set U nits D ialog Box (p.3242 ) (see Customizing U nits (p.657)). Note tha t this unit will b e used f or all futur e inputs of length quan tities . 6.10.14.1.2. Unsc aling the Mesh If you use the wr ong sc ale fac tor, acciden tally click the Scale butt on t wice, or w ant to undo the scaling f or an y other r eason, you c an click the Unscale butt on.“Unscaling ” simply divides each of the no de c oordina tes b y the sp ecified Scale F actors. (Selec ting m in the Mesh Was C reated In list and click ing on Scale will not unsc ale the mesh.) 6.10.14.1.3. Changing the P hysical S ize of the Mesh You c an also use the Scale M esh D ialog Box (p.3238 ) to change the ph ysical siz e of the mesh. For example , if y our 2D mesh is 5 f eet b y 8 f eet, and y ou w ant to mo del the same geometr y with dimen- sions t wice as big (10 f eet b y 16 f eet), you c an en ter 2 for X and Y in the Scaling F actors group box and click Scale.The Domain E xtents will b e up dated t o sho w the new r ange . 6.10.15. Transla ting the M esh You c an “move” the mesh b y applying pr escr ibed off sets t o the C artesian c oordina tes of all the no des in the mesh. This w ould b e nec essar y for a r otating pr oblem if the mesh w ere set up with the axis of rotation not passing thr ough the or igin, or f or an axisymmetr ic pr oblem if the mesh w ere set up with the axis of r otation not c oinciding with the axis . It is also useful if , for e xample , you w ant to mo ve the or igin t o a par ticular p oint on an objec t (such as the leading edge of a fla t pla te) to mak e an X Y plot ha ve the desir ed distanc es on the axis . You c an tr ansla te mesh p oints in ANSY S Fluen t using the Transla te M esh D ialog Box (p.3937 ) (Fig- ure 6.86: The Transla te M esh D ialog Box (p.825)). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 824Reading and M anipula ting M eshesDomain → Mesh → Transf orm → Transla te... Figur e 6.86: The Transla te M esh D ialo g Box 6.10.15.1. Using the Translat e Mesh D ialo g Box The pr ocedur e for tr ansla ting the mesh is as f ollows: 1.Enter the desir ed tr ansla tions in the , , and (f or 3D) directions (tha t is, the desir ed delta in the ax es) in the X,Y, and Z text-en try boxes in the Transla tion O ffsets group b ox.You c an sp ecify p ositiv e or nega tive real numb ers in the cur rent unit of length. 2.Click the Transla te butt on and r edispla y the mesh. The Domain E xtents will b e up dated t o displa y the new e xtents of the tr ansla ted mesh. (Note tha t the Domain E xtents are pur ely inf ormational; you c annot edit them manually .) 6.10.16. Rota ting the M esh The abilit y to rotate the mesh is analo gous t o the abilit y to transla te the mesh in ANSY S Fluen t.You can r otate the mesh ab out the , , or (f or 3D) axis and also sp ecify the r otation or igin. This option is useful in the c ases wher e the str uctural mesh and the CFD mesh ar e off set b y a small angle . You c an r otate the mesh in ANSY S Fluen t using the Rotate M esh D ialog Box (p.3912 ) (Figur e 6.87: The Rotate M esh D ialog Box (p.826)). Domain → Mesh → Transf orm → Rota te... 825Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modifying the M eshFigur e 6.87: The Rota te M esh D ialo g Box 6.10.16.1. Using the R otat e Mesh D ialo g Box The pr ocedur e for rotating the mesh is as f ollows: 1.Specify the r equir ed Rota tion A ngle for the mesh. You c an sp ecify an y positiv e or nega tive real numb er in the c orrect unit of angle . 2.In the Rota tion Or igin group b ox, enter X,Y, and (f or 3D) Z coordina tes to sp ecify a new or igin f or the axis of r otation. 3.In the Rota tion A xis group b ox, enter values f or the X,Y, and (f or 3D) Z axes to sp ecify the v ector for the axis of r otation. 4.Click the Rota te butt on and r edispla y the mesh. The D omain Ex tents will b e up dated t o displa y the new e xtents of the r otated mesh. (Note tha t the D omain Ex tents ar e pur ely inf ormational; you c annot edit them manually .) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 826Reading and M anipula ting M eshes6.10.17. Impr oving the M esh b y Smoothing and S wapping Smoothing and fac e sw apping ar e tools tha t complemen t mesh adaption b y incr easing the qualit y of the final numer ical mesh. Smoothing r epositions the no des, and fac e sw apping mo difies the c ell c on- nectivit y to achie ve these impr ovemen ts in qualit y. Imp ortant Only smo othing tha t is based on qualit y is r ecommended; face sw apping and smo othing based on sk ewness or a Laplacian op erator ha ve mor e limita tions , and supp ort for them may be remo ved in a futur e release . Imp ortant Face sw apping is applic able only t o meshes with tr iangular or t etrahedr al cells. Imp ortant Face sw apping and smo othing based on sk ewness or a Laplacian op erator ar e available only f or ser ial c ases; only qualit y-based smo othing c an b e used f or par allel c ases . For additional inf ormation, see the f ollowing sec tions: 6.10.17.1. Smoothing 6.10.17.2. Face Swapping 6.10.17.3. Combining S kewness-B ased S moothing and F ace Swapping 6.10.17.1. Smo othing The thr ee smo othing metho ds tha t are available in ANSY S Fluen t are: •qualit y-based smo othing This metho d is the only r ecommended metho d, and is a vailable f or all t ypes of meshes in ser ial and par allel. •Laplacian smo othing This metho d is not r ecommended , though it is a vailable f or all t ypes of meshes in ser ial (and is best suit ed f or quadr ilateral and he xahedr al meshes). •skewness-based smo othing This metho d is not r ecommended , though it is a vailable f or tr iangular and t etrahedr al meshes in serial; it c an b e used alt ernatively with fac e sw apping (see Combining S kewness-B ased S moothing and F ace Swapping (p.833)). 6.10.17.1.1. Qualit y-Based Smo othing Smoothing tha t is based on qualit y is p erformed using the Impr ove M esh D ialog Box (p.3836 ) (Fig- ure 6.88: The Impr ove M esh D ialog Box (p.828)). 827Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modifying the M eshDomain → Mesh → Qualit y → Impr ove M esh Q ualit y... Figur e 6.88: The Impr ove M esh D ialo g Box ANSY S Fluen t divides the mesh in to a numb er of “bins ”, each of which c ontain a c ertain numb er of cells. Impr ovemen ts ar e attempt ed on the c ells in those bins tha t exhibit the lo west or thogonal qualit y (as defined in Mesh Q ualit y (p.719)). As par t of this metho d, you sp ecify the p ercentage of the t otal numb er of c ells, in or der t o det ermine ho w man y bins ar e mo dified . Note tha t this smo othing is similar t o when y ou use the mesh/repair-improve/improve text command .The ad vantage of using the Impr ove M esh dialo g box rather than the t ext command is that you c an c ontrol the p ercentage of the c ells tha t ANSY S Fluen t attempts t o impr ove. To perform qualit y-based smo othing , do the f ollowing st eps: 1.In the Impr ove Mesh D ialog Box (p.3836 ) (Figur e 6.88: The Impr ove Mesh D ialog Box (p.828)), enter the Percentage of C ells t o be Impr oved. Imp ortant Qualit y-based smo othing will b e CPU in tensiv e if y ou sp ecify a lar ge v alue f or the Percentage of C ells t o be Impr oved. It is r ecommended tha t you en ter a small v alue initially , and then p erform the smo othing pr ocess multiple times , if nec essar y. Note that the maximum p ercentage allo wed is 10%. 2.Specify the numb er of succ essiv e smo othing sw eeps t o be performed on the mesh in the Numb er of Iterations numb er-en try box.The default v alue is 4. 3.Click the Impr ove butt on. 6.10.17.1.2. Laplacian Smo othing When y ou use this metho d, a Laplacian smo othing op erator is applied t o the unstr uctured mesh t o reposition no des.The new no de p osition is the a verage of the p ositions of its no de neighb ors.The comput ed no de p osition incr emen t is multiplied b y the r elaxa tion fac tor (which is set t o a v alue between 0.0 and 1.0). A v alue of z ero for the r elaxa tion fac tor results in no mo vemen t of the no de, and a v alue of unit y results in mo vemen t equiv alen t to the en tire comput ed incr emen t.Figur e 6.89: Res- ult of S moothing Op erator on N ode P osition (p.829) illustr ates the new no de p osition f or a t ypic al configur ation of quadr ilateral cells.The dashed line is the or iginal mesh and the solid line is the final mesh. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 828Reading and M anipula ting M eshesFigur e 6.89: Result of S moothing Op erator on N ode P osition This r epositioning str ategy impr oves the sk ewness of the mesh, but r elax es the clust ering of no de points. In e xtreme cir cumstanc es, the pr esen t op erator ma y create mesh lines tha t cross o ver the boundar y, creating nega tive cell v olumes .This is most lik ely t o occur near shar p or c oarsely r esolv ed convex corners , esp ecially if y ou p erform multiple smo othing op erations with a lar ge r elaxa tion factor.Figur e 6.90: Initial M esh B efore Smoothing Op eration (p.829) illustr ates an initial t etrahedr al mesh b efore one unr elax ed smo othing it eration cr eates mesh lines tha t cross o ver each other ( Fig- ure 6.91: Mesh S moothing C ausing M esh-Line C rossing (p.830)). Figur e 6.90: Initial M esh B efore Smoothing Op eration 829Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modifying the M eshFigur e 6.91: Mesh S moothing C ausing M esh-Line C rossing The default smo othing par amet ers ar e designed t o impr ove mesh qualit y with minimal ad verse eff ects, but it is r ecommended tha t you sa ve a c ase file b efore smo othing the mesh. If you apply a c onser- vative relaxa tion fac tor and star t with a go od qualit y initial mesh, the fr equenc y of failur e due t o smo othing is e xtremely lo w in t wo dimensions . However, corruption of the mesh t opology occurs much mor e frequen tly in thr ee dimensions , par ticular ly with t etrahedr al meshes . The smo othing op erator c an also b e applied r epeatedly , but as the numb er of smo othing sw eeps increase , the no de p oints ha ve a t endenc y to pull a way from b oundar ies and the mesh t ends t o lose any clust ering char acteristics . To perform Laplacian smo othing , enter the mesh/smooth-mesh text command in the c onsole and respond t o the pr ompts as f ollows: 1.Enter "laplace" for the type of smoothing . 2.Specify the numb er of succ essiv e smo othing sw eeps t o be performed on the mesh in r esponse t o the number of iterations prompt. The default v alue is 4. 3.Specify the fac tor b y which t o multiply the c omput ed p osition incr emen t for the no de in r esponse t o the relaxation factor prompt. The lo wer the fac tor, the mor e reduc tion in no de mo vemen t. 6.10.17.1.3. Skewness-B ased Smo othing When y ou use sk ewness-based smo othing , ANSY S Fluen t applies a smo othing op erator to the mesh, repositioning in terior no des t o lo wer the maximum sk ewness of the mesh. ANSY S Fluen t will tr y to move in terior no des t o impr ove the sk ewness of c ells with sk ewness gr eater than the sp ecified “skewness thr eshold ”.This pr ocess c an b e very time c onsuming , so p erform smo othing only on c ells with high sk ewness . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 830Reading and M anipula ting M eshesImpr oved r esults c an b e obtained b y smo othing the no des se veral times .There ar e in ternal checks that will pr event a no de fr om b eing mo ved if mo ving it c auses the maximum sk ewness t o incr ease , but it is c ommon f or the sk ewness of some c ells t o incr ease when a c ell with a higher sk ewness is being impr oved.Thus, you ma y see the a verage sk ewness incr ease while the maximum sk ewness is decr easing . Imp ortant Carefully c onsider whether the impr ovemen ts to the mesh due t o a decr ease in the maximum sk ewness ar e worth the p otential incr ease in the a verage sk ewness . Performing smo othing only on c ells with v ery high sk ewness (f or e xample , 0.8 or 0.9) ma y reduc e the ad verse eff ects on the a verage sk ewness . To perform sk ewness-based smo othing , enter the mesh/smooth-mesh text command in the console and r espond t o the pr ompts as f ollows: 1.Enter "skewness" for the type of smoothing . 2.Specify the numb er of succ essiv e smo othing sw eeps t o be performed on the mesh in r esponse t o the number of iterations prompt. The default v alue is 4. 3.Specify the minimum c ell sk ewness v alue f or which no de smo othing will b e attempt ed in r esponse t o the skewness threshold prompt. ANSY S Fluen t will tr y to mo ve interior no des t o impr ove the skewness of c ells with sk ewness gr eater than this v alue . By default , skewness thr eshold is set t o 0.4 f or 2D c ases and 0.8 f or 3D c ases . 6.10.17.2. Face Swapping While it is not r ecommended o ver smo othing (and supp ort for it ma y be remo ved in futur e releases), face sw apping c an b e used t o impr ove the qualit y of a tr iangular or t etrahedr al mesh in the ser ial version of ANSY S Fluen t. To perform fac e sw apping , enter the mesh/swap-mesh-faces text command r epeatedly un til the console r eport declar es tha t 0 fac es w ere sw app ed out. The c onsole r eport will displa y the t otal numb er of fac es tha t were visit ed and t ested f or p ossible fac e sw apping . 6.10.17.2.1. Triangular Meshes The appr oach f or tr iangular meshes is t o use the D elauna y cir cle t est t o decide if a fac e shar ed b y two triangular c ells should b e sw app ed. A pair of c ells shar ing a fac e sa tisfies the cir cle t est if the circumcir cle of one c ell do es not c ontain the unshar ed no de of the sec ond c ell.Figur e 6.92: Examples of C ell C onfigur ations in the C ircle Test (p.832) illustr ates c ell neighb ors in the cir cle t est. In c ases wher e the cir cle t est is not sa tisfied , the diagonal or fac e is sw app ed, as illustr ated in Fig- ure 6.93: Swapp ed F aces to Satisfy the D elauna y Circle Test (p.832). 831Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modifying the M eshFigur e 6.92: Examples of C ell C onfigur ations in the C ircle Test Figur e 6.93: Swapp ed F aces t o Satisfy the D elauna y Circle Test Repeated applic ation of the fac e-sw apping t echnique will pr oduce a c onstr ained D elauna y mesh. If you ha ve a D elauna y mesh, it is a unique tr iangula tion tha t maximiz es the minimum angles in the mesh. Thus, the tr iangula tion t ends t oward equila teral cells, providing the most equila teral mesh for the giv en no de distr ibution. For mor e inf ormation on D elauna y mesh gener ation, see Gener ating Tetrahedr al M eshes (p.399) in the F luen t Meshing sec tion of the U ser’s Guide . 6.10.17.2.2. Tetrahedr al Meshes For tetrahedr al meshes , face sw apping c onsists of sear ching f or c onfigur ations of thr ee c ells shar ing an edge and c onverting them in to two cells shar ing a fac e to decr ease sk ewness and the c ell c oun t (see Figur e 6.94: 3D F ace Swapping (p.833)). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 832Reading and M anipula ting M eshesFigur e 6.94: 3D F ace Swapping 6.10.17.3. Combining Sk ewness-B ased Smo othing and F ace Swapping As men tioned in Skewness-B ased S moothing (p.830), skewness-based smo othing should usually b e alternated with fac e sw apping . Guidelines f or this pr ocedur e ar e pr esen ted her e. •Perform four smo othing it erations using a skewness threshold of 0.8 f or 3D c ases , or 0.4 f or 2D cases . •Swap un til the numb er of fac es sw app ed decr eases t o 0. •For 3D meshes , decr ease the skewness threshold to 0.6 and r epeat the smo othing/sw apping pr o- cedur e. 833Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modifying the M eshRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 834Chapt er 7: Cell Z one and B oundar y Conditions This chapt er descr ibes the c ell z one and b oundar y condition options a vailable in ANSY S Fluen t. Details regar ding the c ell z one and b oundar y condition inputs and the in ternal tr eatmen t at boundar ies ar e provided . The inf ormation in this chapt er is divided in to the f ollowing sec tions: 7.1. Overview 7.2. Cell Z one C onditions 7.3. Boundar y Conditions 7.4. Editing M ultiple B oundar y Conditions a t Onc e 7.5. Boundar y Acoustic Wave Models 7.6. User-D efined F an M odel 7.7. Profiles 7.8. Coupling B oundar y Conditions with GT-PO WER 7.9. Coupling B oundar y Conditions with WAVE 7.1. Overview Cell z one and b oundar y conditions sp ecify the flo w and ther mal v ariables on the b oundar ies of y our physical mo del. They are, ther efore, a cr itical comp onen t of y our ANSY S Fluen t simula tions and it is imp ortant tha t the y are sp ecified appr opriately. In this chapt er, most of the c ell z ones and b oundar y conditions will b e descr ibed in detail, and an e x- plana tion of ho w to set them and wher e the y are most appr opriately used will b e pr ovided . 7.1.1. Available C ell Z one and B oundar y Types 7.1.2. The C ell Z one and B oundar y Conditions Task P ages 7.1.3. Changing C ell and B oundar y Zone Types 7.1.4. Setting C ell Z one and B oundar y Conditions 7.1.5. Copying C ell Z one and B oundar y Conditions 7.1.6. Changing C ell or B oundar y Zone N ames 7.1.7. Defining N on-U niform C ell Z one and B oundar y Conditions 7.1.8. Defining and Viewing P aramet ers 7.1.9. Selec ting C ell or B oundar y Zones in the G raphics D ispla y 7.1.10. Operating and P eriodic C onditions 7.1.11. Highligh ting S elec ted B oundar y Zones 7.1.12. Saving and R eusing C ell Z one and B oundar y Conditions 835Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.7.1.1. Available C ell Z one and B oundar y Types The c ell z one and b oundar y zone t ypes a vailable in ANSY S Fluen t are classified as f ollows: Table 7.1: Zone Types b y Categor y Zone Types Categor y axis, degassing , exhaust fan, inlet v ent, intake fan, interface, mass-flo w inlet , mass-flo w outlet , outflo w, outlet v ent, overset , pressur e far-field ,External pressur e inlet , pressur e outlet , symmetr y, velocity inlet , and w all (one-sided only) fan, interior, porous jump , radia tor, RANS/LES in terface, and w all (t wo-sided only)Internal periodic Periodic fluid , solid (p orous media and 3D fans ar e a t ype of fluid c ell) Cells Note tha t internal b oundar y zones ar e connec ted with the c ells on b oth of their fac es, wher eas e xternal boundar y zones ar e connec ted with the c ells on only one of their fac es. 7.1.2. The C ell Z one and B oundar y Conditions Task P ages The Cell Z one C onditions and Boundar y Conditions task pages ( Figur e 7.1: The B oundar y Conditions Task P age (p.837)) displa y lists of the z ones (which c an b e gr oup ed b y name or z one t ype), and allo w you t o revise their settings and p erform other r elated ac tions .They pr ovide an alt ernate setup metho d to working dir ectly in the Outline View tr ee. Setup → Cell Z one C onditions Setup → Boundar y Conditions Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 836Cell Z one and B oundar y ConditionsFigur e 7.1: The B oundar y Conditions Task P age The sec tions tha t follow explain ho w to perform op erations , mostly using the Outline View tr ee, however these same op erations c an also b e complet ed using the Cell Z one C onditions or Boundar y Conditions task page .The sec tions also e xplain ho w to use the mouse and the gr aphics displa y in c onjunc tion with the dialo g box. Note — You c an mo dify individual b oundar y conditions and c ell z ones b y expanding the Cell Z ones and Boundar y Conditions branches in the tr ee, and r ight-click ing the b oundar y condition or c ell z one you w ant to mo dify. 7.1.3. Changing C ell and B oundar y Zone Types Before you set an y cell z one or b oundar y conditions , you should check the z one t ypes of all b oundar y zones and change an y if nec essar y. For e xample , if y our mesh includes a pr essur e inlet , but y ou w ant to use a v elocity inlet inst ead, you will need t o change the pr essur e-inlet z one t o a v elocity-inlet z one . Note tha t external and in ternal b oundar y zones (as list ed in Table 7.1: Zone Types b y Categor y (p.836)) can only b e changed t o a z one of the same c ategor y. The st eps f or changing a z one t ype using the gr aphic al user in terface ar e as f ollows: 1.Selec t the b oundar y or c ell z one in the tr ee (under Setup /Boundar y Conditions or Setup /Cell Z one Conditions ). Note tha t you c an selec t multiple z ones b y holding the Shift or Ctrl keys when selec ting , though y ou must ensur e tha t all of the selec tions ar e of the same c ategor y. 2.Right-click a selec ted b oundar y or c ell z one , and selec t the c orrect zone t ype from the Type sub-menu . 837Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.OverviewYou c an also change the z one t ype using either the define/boundary-conditions/zone-type or the define/boundary-conditions/modify-zones/zone-type text command .To change the t ype for multiple z ones of the same c ategor y thr ough a single ac tion, you c an en ter a list of names or IDs c ontained within a pair of par entheses a t the pr ompt , as sho wn in the f ollowing e xample (which changes z one 4 and 9 t o be pr essur e inlets): > define/boundary-conditions/zone-type zone id/name/list [] (4 9) external-type> pressure-inlet Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 838Cell Z one and B oundar y ConditionsWhen changing the c ell or b oundar y zone t ype, not e the f ollowing: •For zones tha t ha ve the default name (tha t is,- ), the name will b e changed aut oma tically along with the t ype. •When y ou ha ve a lar ge numb er of in ternal b oundar y zones tha t you w ant to change t o or fr om a w all / shado w pair , it is r ecommended tha t you change their t ype with a single ac tion (either b y multi-selec ting in the tr ee or b y using par entheses a t the t ext command pr ompt); this will gr eatly r educ e the pr ocessing time asso ciated with the change . •When changing a w all / shado w pair t o one of the other in ternal t ypes (fan, interior, porous jump , radia tor, or R ANS/LES in terface), you c an selec t either the w all or the w all-shado w to change . In either c ase, the resulting z one will r etain the ID and or ientation of the w all z one and the w all-shado w zone will b e delet ed. •Note tha t you c annot use this metho d to change z one t ypes to or fr om the p eriodic t ype, sinc e additional restrictions e xist f or this b oundar y type.Creating P eriodic Z ones and In terfaces (p.811) explains ho w to create and unc ouple p eriodic z ones . •If you ar e using one of the gener al multiphase mo dels ( VOF, mix ture, or E uler ian), the pr ocedur e for changing types is sligh tly diff erent. See Steps f or S etting B oundar y Conditions (p.2124 ) for details . 7.1.4. Setting C ell Z one and B oundar y Conditions In ANSY S Fluen t, boundar y conditions ar e asso ciated with z ones , not with individual fac es or c ells. If you w ant to combine t wo or mor e zones tha t will ha ve the same b oundar y conditions , see Merging Zones (p.803) for inf ormation ab out mer ging z ones . To set c ell z one and b oundar y conditions f or a par ticular z one , perform one of the f ollowing sequenc es: 1.Right-click the name of z one in the tr ee (under Setup /Boundar y Conditions or Setup /Cell Z one C ondi- tions ). 2.Selec t Edit.... Note You c an gr oup Boundar y Conditions based on adjac ency, allo wing y ou t o see which boundar ies b elong t o the same c ell z one .To do this , right-click the Boundar y Conditions branch in the Outline View tree and selec t Group B y/Adjac enc y. Setup → Boundar y Conditions Group B y → Adjac enc y or 1.Selec t the z one fr om the Zone list in the Cell Z one C onditions or Boundar y Conditions task page . 2.Click the Edit... butt on. 839Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.OverviewThe dialo g box for the selec ted c ell or b oundar y zone will op en, and y ou c an sp ecify the appr opriate conditions . Imp ortant If you ar e using one of the gener al multiphase mo dels ( VOF, mix ture, or E uler ian), the pr o- cedur e for setting c onditions is sligh tly diff erent from tha t descr ibed ab ove. See Steps f or Setting B oundar y Conditions (p.2124 ) for details . You c an use the t ext command:define/boundary-conditions/set/ to define one or mor e settings a t a single or multiple b oundar ies/c ell z ones of a giv en t ype.This facilita tes quick and efficien t setup of c ell/b oundar y conditions f or c ases with lar ge numb ers of z ones . To edit multiple b oundar ies y ou c an either pr ovide a list of b oundar y names / IDs enclosed in par en- thesis: /define/boundary-conditions/set> wall (rotor-hub rotor-shroud rotor-blade-1 rotor-blade-2 stator-hub stator-shroud stator-blade-1 stator-blade-2) zone(s) to set boundary conditions(1) [rotor-hub] (rotor-blade-1 rotor-blade-2) or y ou c an use a wildc ard pa ttern for the b oundar y names: /define/boundary-conditions/set> wall (rotor-hub rotor-shroud rotor-blade-1 rotor-blade-2 stator-hub stator-shroud stator-blade-1 stator-blade-2) zone(s) to set boundary conditions(1) [rotor-hub] (rotor-blade-*) For additional inf ormation on f ormatting lists in the c onsole , see Lists . After en tering the z one(s) y ou w ant to change y ou will b e pr ompt ed f or wha t setting t o change . Pressing Enter will list the a vailable settings . When y ou ha ve changed all of the desir ed settings , press q to exit the define/boundary-condi- tions/set/ command . Note tha t some settings will not tak e eff ect un til af ter y ou ha ve exited the c ommand , by pr essing q. 7.1.5. Copying C ell Z one and B oundar y Conditions You c an c opy cell z ones and b oundar y conditions fr om one z one t o other z ones of the same t ype. If, for e xample , you ha ve se veral w all z ones in y our mo del and the y all ha ve the same b oundar y conditions , you c an set the c onditions f or one w all, and then simply c opy them t o the others . The pr ocedur e for c opying c ell z one or b oundar y conditions is as f ollows: 1.Right-click the name of z one in the tr ee tha t you w ant to copy (under Setup /Boundar y Conditions or Setup /Cell Z one C onditions ) and selec t Copy....This will op en the Copy Conditions dialo g box (Fig- ure 7.2: The C opy Conditions D ialog Box (p.841)). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 840Cell Z one and B oundar y ConditionsFigur e 7.2: The C opy Conditions D ialo g Box 2.In the From C ell Z one or From B oundar y Zone list, confir m tha t the z one tha t has the c onditions y ou want to copy is selec ted. 3.In the To Cell Z ones or To Boundar y Zones list, selec t the z one or z ones t o which y ou w ant to copy the conditions . 4.Click Copy. ANSY S Fluen t will set all of the c ell z ones or b oundar y conditions f or the z ones selec ted in the To Cell Z ones or To Boundar y Zones list t o be the same as the c onditions f or the z one selec ted in the From C ell Z one or From B oundar y Zone list. (You c annot c opy a subset of the c onditions , such as only the ther mal c onditions .) Note tha t you c annot c opy conditions fr om e xternal w alls t o in ternal (tha t is, two-sided) w alls, or vic e versa, if the ener gy equa tion is b eing solv ed, sinc e the ther mal c onditions f or e xternal and in ternal walls ar e diff erent. Imp ortant If you ar e using one of the gener al multiphase mo dels ( VOF, mix ture, or E uler ian), the pr o- cedur e for c opying b oundar y conditions is sligh tly diff erent. See Steps f or C opying C ell Zone and B oundar y Conditions (p.2140 ) for details . 7.1.6. Changing C ell or B oundar y Zone N ames The default name f or a z one is - (for e xample ,pressur e-inlet-7 ). In some c ases , you ma y want to assign mor e descr iptiv e names t o the b oundar y zones . If you ha ve two pr essur e-inlet z ones , for e xample , you migh t want to rename them small-inlet and large-inlet . (Changing the name of a zone will not change its t ype. Instr uctions f or changing a z one’s type ar e pr ovided in Changing C ell and B oundar y Zone Types (p.837).) You c an r ename b oundar ies and c ell z ones dir ectly within the tr ee, by selec ting the z one tha t you want to rename , then click ing the name (slo w double-click). 841Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.OverviewAlternatively, you c an r ename a z one b y following these st eps: 1.Right-click the name of z one in the tr ee (under Setup /Boundar y Conditions or Setup /Cell Z one C ondi- tions ). 2.Selec t Edit... to op en the dialo g box for the selec ted z one . 3.Enter a new name under Zone N ame . 4.Click the OK butt on. Note If you sp ecify a non-default name f or a z one and then change its t ype, the name y ou sp ecified will b e retained; the aut oma tic name change tha t acc ompanies a change in t ype occurs only f or those with the default name . 7.1.7. Defining N on-U niform C ell Z one and B oundar y Conditions Most c onditions a t each t ype of b oundar y zone c an b e defined as pr ofile func tions inst ead of c onstan t values .You c an use a pr ofile c ontained in an e xternally gener ated pr ofile file , or a func tion tha t you create using a user-defined func tion (UDF). Profiles ar e descr ibed in Profiles (p.1051 ), and user-defined func tions ar e descr ibed in the separ ate Fluen t Customiza tion M anual . 7.1.8. Defining and Viewing P aramet ers You c an define a ser ies of c ases based on a set of par ametr ic values .These par amet ers ma y be defined for numer ic cell z one and b oundar y condition settings .This is esp ecially useful if y ou ar e using Work- bench and p erforming par ametr ic studies (optimiza tion), compar ing c ases with diff erent boundar y settings; information ab out such usage c an b e found in see Working with P aramet ers and D esign Points in the Workbench U ser's G uide . If you ar e not r unning ANSY S Fluen t thr ough Workbench, then you c an use the par amet er settings t o define the same b oundar y condition v alue t o diff erent bound- Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 842Cell Z one and B oundar y Conditionsaries ha ving the same units , or t o use the Adjoin t-Based Optimiz er to optimiz e a geometr y for multiple objec tives a t multiple op erating c onditions (see Using the G radien t-Based Optimiz er (p.3168 )). Note For mor e inf ormation ab out using par amet ers with ANSY S Fluen t in ANSY S Workbench, see Working With Input and Output P aramet ers in Workbench in the separ ate Fluen t in Work- bench U ser's G uide . The par amet ers tha t you ha ve defined in the v arious b oundar y condition dialo g boxes ar e acc essed by click ing the Paramet ers... butt on in the Cell Z one C onditions or Boundar y Conditions task page . The Paramet ers dialo g box will op en, as sho wn in Figur e 7.3: The P aramet ers D ialog Box (p.843), listing all of the input par amet ers tha t you ha ve created in the v arious b oundar y condition dialo g boxes. Figur e 7.3: The P aramet ers D ialo g Box In the Paramet ers dialo g box, under the Input P aramet ers list, you c an •Edit the input pr operties using the Paramet er E xpression dialo g box, which is the same dialo g box used to create par amet ers.This dialo g box can also b e acc essed b y selec ting New Input P aramet er... from the drop-do wn lists in the b oundar y conditions dialo g boxes, as descr ibed la ter in this sec tion. Imp ortant If you ar e using ANSY S Fluen t in ANSY S Workbench, you c annot edit the input par amet ers, you c an only view them. For mor e inf ormation, see the separ ate ANSY S Fluen t in ANSY S Workbench U ser's G uide . •Delete input par amet ers tha t are not assigned t o a setting . •More options e xist under the More drop-do wn list (see Working With A dvanced P aramet er Options (p.847)): 843Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.OverviewUse in Scheme P rocedur e displa ys the Use Input P aramet er in Scheme P rocedur e Dialog Box (p.3739 ) wher e you c an apply an input paramet er using a Scheme pr ocedur e. Use in UDF displa ys the Use Input P aramet er for UDF D ialog Box (p.3740 ) wher e you c an mak e an input par amet er available in a user-defined func tion. In the Paramet ers dialo g box, under the Output P aramet ers list, you c an also •Create output par amet ers.These ar e single v alues gener ated b y existing r eports or monit ors.You c an gener ate the output par amet ers f or Fluxes,Forces,Surface,Volume ,Drag,Lift,Momen ts, and User Defined report definitions .These output par amet ers ar e discussed in gr eater detail in Creating Output Paramet ers (p.2935 ). •Edit e xisting output par amet ers. •More options e xist under the More drop-do wn list: Delet e remo ves the selec ted output par amet er fr om the list of Output P aramet ers. Rename allows you t o edit the name of the output par amet er thr ough the Rename dialo g box. Print to Console will output v alues t o the c onsole windo w. If you selec t multiple output par amet ers, then the output includes v alues fr om multiple output par amet ers. Print All to Console outputs the v alues fr om all output par amet ers t o the c onsole windo w. Write... allows you t o store the output t o a file . A dialo g box is displa yed allo wing y ou t o pr ovide a file name . Write All... prompts y ou f or a file name and then wr ites the v alues f or all of the output par amet ers t o a file . Imp ortant Changing the units f or a quan tity changes the v alue f or an y input par amet er using tha t quan tity. Note Various ANSY S Fluen t setup-r elated input quan tities (of t ype real and pr ofile) c an b e assigned to an input par amet er (indic ated b y the New Input P aramet er... option in the c orresponding drop-do wn list or menu ne xt to the field). Clicking this option op ens the Figur e 7.5: The Paramet er Expr ession D ialog Box (p.846) wher e you c an cr eate the input par amet er. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 844Cell Z one and B oundar y Conditions7.1.8.1. Creating a N ew P aramet er You c an cr eate a new c ell z one or b oundar y condition par amet er, as sho wn in Figur e 7.4: The N ew Input P aramet er/Expr ession... Selec tion (p.845). Figur e 7.4: The N ew Input P aramet er/E xpression... Selec tion When y ou selec t New Input P aramet er/E xpression... from the dr op-do wn list , the Paramet er E x- pression dialo g box (Figur e 7.5: The P aramet er Expr ession D ialog Box (p.846)) will op en wher e you will •Enter the Name of the par amet er expression. •Specify the Definition as a c onstan t. •The Used In field displa ys inf ormation ab out wher e the par amet er is utiliz ed. Note tha t this field will b e popula ted af ter you cr eate an input par amet er. 845Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.OverviewFigur e 7.5: The P aramet er E xpression D ialo g Box Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 846Cell Z one and B oundar y ConditionsOnc e the par amet er is defined in the Paramet er E xpression dialo g box, the name of the par amet er will app ear in the dr op-do wn list of the pr operty you ar e defining , as seen in Figur e 7.4: The N ew Input Paramet er/Expr ession... Selec tion (p.845). Imp ortant Input par amet er e xpressions must b e dir ectly defined as a c onstan t value including appr o- priate units; it ma y not r eference another e xpression. Note ANSY S Fluen t aut oma tically cr eates gener ic default names f or new input and output paramet ers (f or e xample ,parameter_1 ,parameter_2 ,parameter_3 , and so on) I f a par amet er is delet ed, the default name is not r eused . For e xample , if y ou ha ve paramet- er_1 ,parameter_2 , and parameter_3 , then delet e parameter_2 and cr eate a new paramet er, the default name f or the new par amet er will b e parameter_4 . 7.1.8.2. Work ing With A dvanc ed P aramet er O ptions Various ANSY S Fluen t setup r elated input quan tities c an b e assigned t o an input par amet er.You c an define a ser ies of simula tions based on a set of par ametr ic values tha t are managed b oth in ANSY S Fluen t and in Workbench. These par amet ers ma y be defined f or numer ic cell z one and b oundar y condition settings using the New Input P aramet er… option in the c orresponding dr op-do wn list or menu adjac ent to a sp ecific input setting . However, various ANSY S Fluen t settings ar e not supp orted by these metho ds. You c an mitiga te this limita tion using input par amet ers thr ough Scheme pr ocedur es and user-defined func tions (UDFs), and define input par amet ers f or v arious ANSY S Fluen t simula tion r elated settings . 7.1.8.2.1. Defining Scheme P rocedur es With Input P aramet ers 7.1.8.2.2. Defining UDFs With Input P aramet ers 7.1.8.2.3. Using the Text User In terface to Define UDFs and Scheme P rocedur es With Input P aramet ers 7.1.8.2.1. Defining Scheme P rocedur es With Input P aramet ers To use a Scheme pr ocedur e with input par amet ers, in the Paramet ers dialo g box under Input Paramet ers, selec t More, then cho ose Use in Scheme P rocedur e to displa y the Use Input P aramet er in Scheme P rocedur e Dialog Box (p.3739 ) wher e you c an r egist er the input par amet ers tha t can b e used in Scheme pr ocedur es dur ing c alcula tions . A text user in terface command is also a vailable , descr ibed in Using the Text User In terface to Define UDFs and Scheme P rocedur es With Input P ara- met ers (p.850). 847Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.OverviewFigur e 7.6: Use Input P aramet er in Scheme P rocedur e D ialo g Box Use the Selec t butt on t o op en the Selec t Input P aramet er D ialog Box (p.3472 ) wher e an input par a- met er can b e chosen. Enter a Scheme P rocedur e name or b ody star ting with lambda tha t should receive a r eal ar gumen t (the v alue of the selec ted input par amet er). For e xample , if the f ollowing Scheme pr ocedur e called my-funct is defined as a Scheme file tha t gets loaded in to the cur rent session, (define my-funct (lambda (value ) (ti-menu-load-string (format #f "/solve/set/under-relaxation/pressure ~g" value)))) then en ter my-funct for the Scheme P rocedur e. Other wise , you c an dir ectly en ter the f ollowing code f or the Scheme P rocedur e: (lambda (value)(ti-menu-load-string (args->string '/solve/set/under-relaxation/pressure value))) Click Define to popula te the Regist ered List . Use Delet e to delet e the use of the selec ted input variable , but not the asso ciated input par amet er (the input par amet er has t o be delet ed separ ately in the Paramet ers dialo g box). Use Print to pr int out details of the r egist ered input par amet ers. Imp ortant While wr iting Scheme pr ocedur es, you should use the "ar gs->str ing" help pr ocedur e inst ead of using double quot es. For e xample: (lambda ( value1) (display (args->string 'Changing-Theta-Divisions-value= value1)) (ti-menu-load-string (args->string '/define/models/radiation/discrete-ordinates? 'yes value1 '_ '_ '_)) ) Alternatively, you c ould also wr ite: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 848Cell Z one and B oundar y Conditions(lambda ( value1) (display (args->string 'Changing-Theta-Divisions-value= value1)) (ti-menu-load-string (apply args->string `(/define/models/radiation/discrete-ordinates? yes ,value1 _ _ _) )) ) wher e the ` char acter af ter args->string is the gr ave acc ent char acter (not a single quot e) and the _ char acter st ores the default v alue of the cur rent text user in terface prompt. Note tha t the first o ccur rence of value1 is the Scheme v ariable , while the sec ond occur rence of value1 will b e replac ed b y the v alue st ored in the v ariable .This metho d elimina tes the need t o sp ecify a single quot e for all ar gumen ts. Also not e tha t if y ou en ter a scheme pr ocedur e body in the Use Input P aramet er in Scheme P rocedur e dialo g box, you should c ombine the scheme pr ocedur e lines in to one single line . 7.1.8.2.2. Defining UDFs With Input P aramet ers To use a UDF with input par amet ers, in the Paramet ers dialo g box under Input P aramet ers, selec t More, then cho ose Use in UDF to displa y the Use Input P aramet er for UDF D ialog Box (p.3740 ) wher e you c an r egist er the input par amet ers tha t can b e used in UDF func tions dur ing c alcula tions . A text user in terface command is also a vailable , descr ibed in Using the Text User In terface to Define UDFs and Scheme P rocedur es With Input P aramet ers (p.850). Figur e 7.7: Use Input P aramet er f or UDF D ialo g Box Use the Selec t butt on t o op en the Selec t Input P aramet er D ialog Box (p.3472 ) wher e an input par a- met er can b e chosen. Click Define to popula te the Regist ered List . Use Delet e to delet e the use of the selec ted input v ariable , but not the asso ciated input par amet er (the input par amet er has t o be delet ed separ ately in the Paramet ers dialo g box). Click Print to pr int out the par amet er ID of the r egist ered input par amet er.This ID should b e used t o acc ess the v alue of the par amet er in UDF . By regist ering the input par amet er, ANSY S Fluen t knows tha t this input par amet er is b eing used b y a UDF . In the UDF C func tion, you c an acc ess the r egist ered input par amet er v alue using the RP_Get_Input_Parameter macr o. For e xample , 849Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Overviewreal value = RP_Get_Input_Parameter(“real-4”), wher e real-4 is an input par amet er ID obtained using the Print feature. 7.1.8.2.3. Using the Text User Int erface to Define UDFs and Scheme P rocedur es With Input Paramet ers The /define/parameters/input-parameters/advance/use-in text interface command can also b e used t o define input par amet ers and Scheme pr ocedur es and user-defined func tions . The Scheme pr ocedur es c an use other t ext user in terface (TUI) c ommands in ANSY S Fluen t to change the desir ed simula tion settings in a par ametr ic manner . Each numer ical comp onen t of the TUI command str ing c an b e mar ked and tr eated as a par amet er. Setting up ad vanced input par amet ers requir es using Scheme func tions tha t use t ext interface commands t o apply new v alues . Onc e defined , these input par amet ers ar e displa yed in the Paramet ers dialo g box alongside other input par amet ers. The input par amet er passes a c onstan t numer ic value t o the r egist ered/pr ovided Scheme func tion. Therefore, the asso ciated Scheme func tion (and c orresponding ANSY S Fluen t text command) uses the c onstan t par amet er v alues using the units tha t were alr eady defined f or the designa ted t ext command quan tity. /define/parameters/input-parameters/advance Enter the ad vanced input par amet ers menu . use-in/ Allows you t o use an input par amet er in a Scheme pr ocedur e or in a UDF .The following e xamples demonstr ates ho w to use an input par amet er using a Scheme pr ocedur e.The Scheme pr ocedur e body can b e wr itten a t the pr ompt itself : /define/parameters/input-parameters/advance> use-in Select type:> scheme-proc Name of parameter ["parameter-1"] parameter-1 value [0] 0.3 Enter the name/body of apply-function [()] (lambda (value ) (ti-menu-load-string (format #f "/solve/set/under-relaxation/pressure ~g" value))) or it c an b e wr itten in a Scheme file (f or e xample ,my-funct ) /define/parameters/custom-input-parameters> use-in Select type:> scheme-proc Name of parameter ["parameter-1"] parameter-1 value [0] 0.3 Enter the name/body of apply-function [()] my-funct wher e the my-funct Scheme file c ontents ar e: (define my-funct (lambda (value ) (ti-menu-load-string (format #f "/solve/set/under-relaxation/pressure ~g" value)))) The f ollowing e xample demonstr ates ho w to use an input par amet er using a UDF : /define/parameters/input-parameters/advance> use-in Select type:> udf-side Name of parameter ["parameter-1"] parameter-1 value [0] 0.3 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 850Cell Z one and B oundar y Conditionsdelete Deletes the use of the selec ted input v ariable , but not the asso ciated input par amet er (the input paramet er has t o be delet ed separ ately). Using the wildc ard ‘*’ allo ws you t o delet e all cust om input variable a t onc e. list Shows usage of input par amet ers f or Scheme pr ocedur es and f or UDFs 7.1.9. Selec ting C ell or B oundar y Zones in the G raphics D ispla y During setup y ou will w ant to displa y boundar y conditions , which c an b e acc omplished using the Mesh D ispla y Dialog Box (p.3239 ).You also ha ve the option t o highligh t boundar ies in the tr ee, right- click them, and selec t Displa y or Add t o G raphics .This f eature is par ticular ly useful if y ou ar e setting up a pr oblem f or the first time or if y ou w ant to visually c onfir m the lo cation of a par ticular b oundar y condition. Figur e 7.8: Selec ting M ultiple B oundar ies f or D ispla y in the G raphics Windo w 851Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.OverviewConversely , onc e a mesh or other gr aphics objec t is displa yed, you c an selec t boundar ies using a lef t mouse click (use Ctrl or Shift to selec t multiple b oundar ies)—the selec ted b oundar ies ar e highligh ted in the tr ee.The b oundar y descr iption in the tr ee includes the z one IDs , which c an help y ou diff erentiate the z ones .You c an also r ight-click selec ted b oundar ies in the gr aphics windo w to perform a numb er of options including pr inting inf ormation ab out the b oundar ies (sur face IDs , zone IDs , sur face gr oups , and so on), fusing z ones , and cr eating gr aphics objec ts. For e xample , refer to Figur e 7.9: Example Op- erations f or M ultiple S elec ted Sur faces in the G raphics Windo w (p.852), which sho ws some op erations that are available f or the selec ted sur faces (highligh ted in ligh t green). Figur e 7.9: Example Op erations f or M ultiple S elec ted S urfaces in the G raphics Windo w 7.1.10. Op erating and P eriodic C onditions The Cell Z one C onditions and Boundar y Conditions task pages allo w you t o acc ess the Operating Conditions dialo g box, wher e you c an set the op erating pr essur e, reference pr essur e lo cation, include the eff ects of gr avity, and sp ecify other op erating v ariables , as discussed in Modeling B asic F luid Flow (p.1197 ). Setup → Cell Z one C onditions → Operating C onditions ... Setup → Boundar y Conditions → Operating C onditions ... The Periodic C onditions dialo g box can b e acc essed fr om the Boundar y Conditions task page . For a detailed descr iption of this dialo g box’s inputs , refer to Periodic F lows (p.1206 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 852Cell Z one and B oundar y ConditionsSetup → Boundar y Conditions → Periodic C onditions ... 7.1.11. Highligh ting S elec ted B oundar y Zones To highligh t a selec ted b oundar y zone of a mo del tha t is displa yed in the gr aphics windo w, enable the Highligh t Zone option in the Boundar y Conditions task page . Imp ortant Note tha t this is only applic able t o 3D c ases and is a vailable only in the Boundar y Conditions task page . There ar e two ways in which y ou c an highligh t a b oundar y zone in the gr aphics windo w, after enabling the Highligh t Zone option: •Selec t the z one b y highligh ting it in the Zone list, in the Boundar y Conditions task page . •Use the mouse-pr obe butt on and selec t the z one in the gr aphics windo w. The selec ted z one in the gr aphics windo w will b e highligh ted in a c yan c olor , which is the default color .You c an change the c olor using the f ollowing t ext command: display → set → colors → highlight-color If you w ant to highligh t a b oundar y zone tha t is not displa yed in the gr aphics windo w, ANSY S Fluen t will displa y tha t boundar y zone in the gr aphics windo w and then highligh t it. If you disable the Highligh t Zone option, the displa yed b oundar y zone will b e remo ved fr om the sc ene (gr aphics windo w) and your mo del will b e redrawn t o its or iginal view . 7.1.12. Saving and Reusing C ell Z one and B oundar y Conditions You c an sa ve cell z one and b oundar y conditions t o a file so tha t you c an use them t o sp ecify the same conditions f or a diff erent case, as descr ibed in Reading and Writing B oundar y Conditions (p.596). 7.2. Cell Z one C onditions Cell z ones c onsist of fluids and solids . Porous z ones and 3D fans in ANSY S Fluen t are treated as fluid zones . A detailed descr iption of the v arious c ell z ones is giv en in the sec tions tha t follow. 7.2.1. Fluid C onditions 7.2.2. Solid C onditions 7.2.3. Porous M edia C onditions 7.2.4. 3D F an Z ones 7.2.5. Fixing the Values of Variables 7.2.6. Locking the Temp erature for Solid and S hell Z ones 7.2.7. Defining M ass, Momen tum, Ener gy, and O ther S ources 853Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Cell Z one C onditions7.2.1. Fluid C onditions A fluid z one is a gr oup of c ells f or which all ac tive equa tions ar e solv ed.The only r equir ed input f or a fluid z one is the t ype of fluid ma terial.You must indic ate which ma terial the fluid z one c ontains so that the appr opriate ma terial pr operties will b e used . Imp ortant If you ar e mo deling multiphase flo w, you will not sp ecify the ma terials her e; you will cho ose the phase ma terial when y ou define the phases , as descr ibed in Defining the P hases f or the VOF M odel (p.2171 ). Imp ortant If you ar e mo deling sp ecies tr ansp ort and/or c ombustion, you c an sp ecify the ma terial as either a mix ture or a fluid .The mix ture ma terial has t o be the same as tha t sp ecified in the Species M odel dialo g box when y ou enable the mo del. The fluid z ones , being of diff erent material t ypes, must not b e contiguous . Optional inputs allo w you t o set sour ces or fix ed v alues of mass , momen tum, hea t (temp erature), tur- bulenc e, species , and other sc alar quan tities .You c an also define motion f or the fluid z one . If ther e are rotationally p eriodic b oundar ies adjac ent to the fluid z one , you must sp ecify the r otation axis . If you ar e mo deling turbulenc e using one of the - mo dels , the - mo del, or the S palar t-Allmar as model, you c an cho ose t o define the fluid z one as a laminar flo w region. If you ar e mo deling r adia tion using the DO mo del, you c an sp ecify whether or not the fluid par ticipa tes in r adia tion. Warning In gener al, disabling Participa tes in R adia tion for fluid z ones is not r ecommended , as it can pr oduce er roneous r esults .There ar e rare cases when it is acc eptable: for e xample , if the domain c ontains multiple fluid z ones , disabling this option f or z ones wher e radia tion is negligible ma y sa ve computa tional time without aff ecting the r esults . Imp ortant For inf ormation ab out p orous z ones and 3D fan z ones , see Porous M edia C onditions (p.864) and 3D F an Z ones (p.899), respectively. 7.2.1.1. Inputs for F luid Z ones You will set all fluid c onditions in the Fluid D ialog Box (p.3457 ) (Figur e 7.10: The F luid D ialog Box (p.855)), which is acc essed fr om the Cell Z one C onditions task page (as descr ibed in Setting C ell Z one and Boundar y Conditions (p.839)). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 854Cell Z one and B oundar y ConditionsFigur e 7.10: The F luid D ialo g Box 7.2.1.1.1. Defining the F luid M aterial To define the ma terial c ontained in the fluid z one , selec t the appr opriate item in the Material N ame drop-do wn list. This list will c ontain all fluid ma terials da tabase) in the Create/Edit M aterials D ialog Box (p.3386 ). If you w ant to check or mo dify the pr operties of the selec ted ma terial, you c an click Edit... to op en the Edit M aterial dialo g box; this dialo g box contains just the pr operties of the se- lected ma terial, not the full c ontents of the standar d Create/Edit M aterials dialo g box. Imp ortant If you ar e mo deling sp ecies tr ansp ort or multiphase flo w, the Material N ame list will not app ear in the Fluid dialo g box. For sp ecies c alcula tions , the mix ture ma terial for all fluid zones will b e the ma terial y ou sp ecified in the Species M odel D ialog Box (p.3294 ). For multiphase flo ws, the ma terials ar e sp ecified when y ou define the phases , as descr ibed in Defining the P hases f or the VOF M odel (p.2171 ). 7.2.1.1.2. Defining S our ces If you w ant to define a sour ce of hea t, mass , momen tum, turbulenc e, species , or other sc alar quan tity within the fluid z one , you c an do so b y enabling the Sour ce Terms option. See Defining Mass, Momen tum, Ener gy, and O ther S ources (p.908) for details . 7.2.1.1.3. Defining F ixed Values If you w ant to fix the v alue of one or mor e variables in the fluid z one , rather than c omputing them during the c alcula tion, you c an do so b y enabling the Fixed Values option. See Fixing the Values of Variables (p.904) for details . 855Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Cell Z one C onditions7.2.1.1.4. Specifying a L aminar Z one When y ou ar e calcula ting a turbulen t flo w, it is p ossible t o “turn off ” turbulenc e mo deling in a sp e- cific fluid z one .To disable turbulenc e mo deling , turn on the Laminar Z one option in the Fluid dialo g box.This is useful if y ou k now tha t the flo w in a c ertain r egion is laminar . For e xample , if y ou k now the lo cation of the tr ansition p oint on an air foil, you c an cr eate a laminar/turbulen t transition boundar y wher e the laminar c ell z one b orders the turbulen t cell z one .This f eature allo ws you t o model turbulen t transition on the air foil. By default , the Laminar Z one option will set the turbulen t visc osity, , to zero and disable turbulenc e produc tion in the fluid z one .Turbulen t quan tities will still b e transp orted thr ough the z one , but eff ects on fluid mixing and momen tum will b e ignor ed. If you w ant to keep the turbulen t visc osity, you c an do so using the t ext command define/ boundary-conditions/fluid .You will b e ask ed if you w ant to Set Turbulent Viscosity to zero within laminar zone? . If your r e- sponse is no, ANSY S Fluen t will set the pr oduc tion t erm in the turbulenc e transp ort equa tion t o zero, but will r etain a nonz ero . Disabling turbulenc e mo deling in a fluid z one c an b e applied t o all the turbulenc e mo dels e xcept the Lar ge E ddy Simula tion (LES) mo del. 7.2.1.1.5. Specifying a R eac tion Mechanism If you ar e mo deling sp ecies tr ansp ort with r eactions , you c an enable a r eaction mechanism in a fluid zone b y tur ning on the Reac tion option and selec ting an a vailable mechanism fr om the Reac tion Mechanism drop-do wn list. See Defining Z one-B ased R eaction M echanisms (p.1642 ) for mor e inf orm- ation ab out defining r eaction mechanisms . 7.2.1.1.6. Specifying the R otation A xis If ther e ar e rotationally p eriodic b oundar ies adjac ent to the fluid z one or if the z one is r otating , either the mesh or its r eference frame , you must sp ecify the r otation axis .To define the axis f or a moving r eference frame pr oblem, set the Rota tion-A xis D irection and Rota tion-A xis Or igin under the Referenc e Frame tab .To define the axis f or a mo ving mesh pr oblem, set the Rota tion-A xis Direction and Rota tion-A xis Or igin under the Mesh M otion tab . Note If a fr ame motion and a mesh motion ar e sp ecified a t the same z one and this z one has r otationally p eriodic b oundar ies adjac ent to it, then b oth ax es ha ve to be coaxial. Other wise , the p eriodicit y assumption is not v alid and y ou will r eceive a w arning message . In addition, the mesh check will fail. The c ell z one axis is indep enden t of the axis of r otation used b y an y adjac ent wall z ones or an y other c ell z ones . For 3D pr oblems , the axis of r otation is the v ector fr om the Rota tion-A xis Or igin in the dir ection of the v ector giv en b y your Rota tion-A xis D irection inputs f or the fr ame of r eference and the mesh motion. For 2D non-axisymmetr ic pr oblems , you will sp ecify only the Rota tion-A xis Origin ; the axis of r otation is the -direction v ector passing thr ough the sp ecified p oint. (The dir- ection is nor mal t o the plane of y our geometr y so tha t rotation o ccurs in the plane .) For 2D axisymmetr ic pr oblems , you will not define the axis: the r otation will alw ays be ab out the axis , with the or igin a t (0,0). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 856Cell Z one and B oundar y Conditions7.2.1.1.7. Defining Z one Motion To define z one motion f or a mo ving r eference frame (MRF), enable the Frame M otion option in the Fluid dialo g box. Set the appr opriate par amet ers in the e xpanded p ortion of the dialo g box, under the Referenc e Frame tab . To define z one motion f or a mo ving (sliding) mesh, enable the Mesh M otion option in the Fluid dialo g box. Set the appr opriate par amet ers in the e xpanded p ortion of the dialo g box, under the Mesh M otion tab . See Setting U p the S liding M esh P roblem (p.1258 ) for details . For c ases tha t do not c ontain z ones with motion sp ecified in a r elative frame t o another z one , selec t absolut e from the Rela tive To Cell Z one drop-do wn list. Here, the v elocity and r otation c omp onen ts are sp ecified in an absolut e reference frame , which is the default setting , as sho wn in Figur e 7.11: Ro- tation S pecified in the A bsolut e Reference Frame (p.857). If no mo ving z ones ar e pr esen t in the simula tion, then absolut e will b e the only a vailable selec tion. See The M ultiple R eference Frame Model for mor e inf ormation. Figur e 7.11: Rota tion S pecified in the A bsolut e Ref erenc e Frame For c ases wher e you ha ve a mo ving z one sp ecified r elative to another mo ving z one , selec t the c ell zone c arrying the pr imar y motion fr om the Rela tive To Cell Z one drop-do wn list under the Referenc e Frame tab or the Mesh M otion tab . Note tha t for such c ases ,Rota tion-A xis Or igin (Rela tive) will app ear in the in terface, signifying c oordina tes relative to the z one selec ted fr om the Rela tive To Cell Z one drop-do wn list. 857Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Cell Z one C onditionsFigur e 7.12: Rotation S pecified R elative to a M oving Z one (p.858) illustr ates tha t the r otational axis origin of the small r otating z one is sp ecified r elative to the c ell z one c arrying the pr imar y motion (having lo cal coordina te sy stem ). Figur e 7.12: Rota tion S pecified Rela tive to a M oving Z one Note The Rela tive To Cell Z one list will c onsist of all mo ving c ell z ones with an absolut e motion specific ation (tha t is z ones tha t are mo ving , but their motion is not r elative to some other zone), excluding the cur rent cell z one . For pr oblems tha t include linear , transla tional motion of the fluid z one , specify the Transla tional Velocity by setting the X,Y, and Z comp onen ts under the Mesh M otion tab . For pr oblems tha t in- clude r otational motion, specify the r otational Speed under Rota tional Velocity.The r otation axis is defined as descr ibed ab ove. Note tha t the sp eed c an b e sp ecified as a c onstan t value or a tr ansien t profile .The tr ansien t profile ma y be in a file f ormat, as descr ibed in Defining Transien t Cell Z one and B oundar y Conditions (p.1066 ), or a UDF macr o (DEFINE_TR ANSIENT_PR OFILE). Specifying the in- dividual v elocities as either a pr ofile or a UDF allo ws you t o sp ecify a single c omp onen t of the fr ame motion individually . However, you c an also sp ecify the fr ame motion using a user-defined func tion. This ma y pr ove to be quit e convenien t if y ou ar e mo deling a mor e complic ated motion of the Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 858Cell Z one and B oundar y Conditionsmoving r eference frame , wher e the ho oking of man y diff erent user-defined func tions or pr ofiles c an be cumb ersome . Imp ortant If you need t o swit ch b etween the MRF and mo ving mesh mo dels , simply click the Copy To M esh M otion for z ones with a mo ving fr ame of r eference and Copy to Frame M otion for z ones with mo ving meshes t o transf er motion v ariables , such as the ax es, frame or igin, and v elocity comp onen ts b etween the t wo mo dels .The v ariables used f or the or igin, axis , and v elocity comp onen ts, as w ell as f or the UDF DEFINE_ZONE_MOTION will b e copied . This is par ticular ly useful if y ou ar e doing a st eady-sta te MRF simula tion t o obtain an initial solution f or a tr ansien t Moving M esh simula tion in a turb omachine . See Modeling F lows with M oving R eference Frames (p.1227 ) for details ab out mo deling flo ws in moving r eference frames . Details ab out the fr ame motion UDF c an b e found in DEFINE_ZONE_MOTION in the Fluen t Customiza tion M anual . 7.2.1.1.8. Defining R adiation P aramet ers If you ar e using the DO r adia tion mo del, you c an sp ecify whether or not the fluid z one par ticipa tes in radia tion using the Participa tes in R adia tion option. See Defining B oundar y Conditions f or R adi- ation (p.1514 ) for details . 7.2.2. Solid C onditions A “solid ” zone is a gr oup of c ells f or which no flo w equa tions ar e solv ed: in a fluid simula tion, only a heat conduc tion pr oblem is solv ed; in an in trinsic fluid-str ucture in teraction (FSI) simula tion, displac e- men t and str ess t ensor c omp onen ts ar e calcula ted.The ma terial b eing tr eated as a solid ma y ac tually be a fluid , but it is assumed tha t no c onvection is tak ing plac e.The only r equir ed input f or a solid z one is the t ype of solid ma terial.You must indic ate which ma terial the solid z one c ontains so tha t the ap- propriate ma terial pr operties will b e used . Optional inputs allo w you t o set a v olumetr ic hea t gener ation rate (hea t sour ce) or a fix ed v alue of t emp erature.You c an also define motion f or the solid z one . If ther e ar e rotationally p eriodic b oundar ies adjac ent to the solid z one , you must sp ecify the r otation axis. If you ar e mo deling r adia tion using the DO mo del, you c an sp ecify whether or not the solid ma- terial par ticipa tes in r adia tion. 7.2.2.1. Inputs for S olid Z ones You will set all solid c onditions in the Solid D ialog Box (p.3467 ) (Figur e 7.13: The S olid D ialog Box (p.860)), which is op ened fr om the Cell Z one C onditions task page (as descr ibed in Setting C ell Z one and Boundar y Conditions (p.839)). 859Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Cell Z one C onditionsFigur e 7.13: The S olid D ialo g Box 7.2.2.1.1. Defining the S olid M aterial To define the ma terial c ontained in the solid z one , selec t the appr opriate item in the Material N ame drop-do wn list. This list will c ontain all solid ma terials da tabase) in the Create/Edit M aterials D ialog Box (p.3386 ). If you w ant to check or mo dify the pr operties of the selec ted ma terial, you c an click Edit... to op en the Edit M aterial dialo g box; this dialo g box contains just the pr operties of the se- lected ma terial, not the full c ontents of the standar d Create/Edit M aterials dialo g box. 7.2.2.1.2. Defining a H eat S our ce If you w ant to define a sour ce of hea t within the solid z one , you c an do so b y enabling the Sour ce Terms option. See Defining M ass, Momen tum, Ener gy, and O ther S ources (p.908) for details . 7.2.2.1.3. Defining a F ixed Temp eratur e If you w ant to fix the v alue of t emp erature in the solid z one , rather than c omputing it dur ing the calcula tion, you c an do so b y enabling the Fixed Values option. See Fixing the Values of Vari- ables (p.904) for details . 7.2.2.1.4. Specifying the R otation A xis If ther e ar e rotationally p eriodic b oundar ies adjac ent to the solid z one or if the z one is r otating , either the mesh or its r eference frame , you must sp ecify the r otation axis .To define the axis f or a moving r eference frame pr oblem, set the Rota tion-A xis D irection and Rota tion-A xis Or igin under Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 860Cell Z one and B oundar y Conditionsthe Referenc e Frame tab .To define the axis f or a mo ving mesh pr oblem, set the Rota tion-A xis Direction and Rota tion-A xis Or igin under the Mesh M otion tab . Note If a fr ame motion and a mesh motion ar e sp ecified a t the same z one and this z one has r otationally p eriodic b oundar ies adjac ent to it, then b oth ax es ha ve to be coaxial. Other wise , the p eriodicit y assumption is not v alid and y ou will r eceive a w arning message . In addition, the mesh check will fail. The c ell z one axis is indep enden t of the axis of r otation used b y an y adjac ent wall z ones or an y other c ell z ones . For 3D pr oblems , the axis of r otation is the v ector fr om the Rota tion-A xis Or igin in the dir ection of the v ector giv en b y your Rota tion-A xis D irection inputs f or the fr ame of r eference and the mesh motion. For 2D non-axisymmetr ic pr oblems , you will sp ecify only the Rota tion-A xis Origin ; the axis of r otation is the -direction v ector passing thr ough the sp ecified p oint. (The dir- ection is nor mal t o the plane of y our geometr y so tha t rotation o ccurs in the plane .) For 2D axisymmetr ic pr oblems , you will not define the axis: the r otation will alw ays be ab out the axis , with the or igin a t (0,0). 7.2.2.1.5. Defining Z one Motion To define r otational motion f or a solid , enable the Frame M otion option under Cell Z one C onditions . Set the appr opriate par amet ers in the e xpanded p ortion of the dialo g box, under the Referenc e Frame tab . Note tha t although the user in terface implies tha t solid z one motion is mo deled b y solving the equa tions in a r otating r eference frame , it is ac tually implemen ted b y solving the equa tions in the absolut e frame using an additional ad vection t erm in the solid ener gy equa tion. This additional ad- vection t erm must b e div ergenc e-free, which r equir es tha t the sp ecified motion b e tangen tial t o the boundar ies. If the motion has a nor mal c omp onen t, the solv er cannot achie ve ener gy conser vation. The only e xception, for which nor mal motion is p ermitt ed, is a c oupled w all or mesh in terface between t wo solid z ones ha ving the same ma terial and motion. The solv er will pr int a w arning t o the solv er tr anscr ipt the first time it enc oun ters a solid v elocity ha ving a signific ant nor mal c omp onen t at an y other b oundar y type. The f ollowing e xamples illustr ate valid solid z one motion definitions: Figur e 7.14: Single Rota ting S olid Z one 861Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Cell Z one C onditionsFigur e 7.15: Rota ting solid z one separ ated fr om another fluid or solid z one separ ated b y a surface of r evolution. Figur e 7.16: Multiple r otating solid z ones ha ving the same ma terial and motion sp ecific ations , separ ated b y mesh in terfaces or c oupled w alls . The f ollowing e xamples illustr ate invalid solid z one motion definitions: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 862Cell Z one and B oundar y ConditionsFigur e 7.17: Rota ting solid with b oundar ies which ar e not tangen tial t o the motion. The f ollowing e xample illustr ates a solid motion definition which is f ormally in valid, but ma y be ac- ceptable f or engineer ing pur poses: Figur e 7.18: Two solids in c ontact with some squish. At the c ontact, the r otational motion has some nor mal c omp onen t, so the solv er will not achie ve global ener gy conser vation. However, the t emp erature field migh t still b e acc eptable f or engineer ing pur poses . If the mo ving solid is separ ated fr om a fluid z one b y a c oupled w all, you must also r ememb er to specify the w all v elocity for the fluid b oundar y to be consist ent with the solid motion. Limita tions: •The eff ects of solid motion ar e applied only t o the ener gy equa tion and the str uctural mo del calcula tions . User-defined sc alars do not include the eff ects of solid motion. •Only r otating motion c an cur rently b e mo deled . •Solid motion thr ough a b oundar y is not p ermitt ed; tha t is, ther e is no supp ort for a ‘solid inlet ’ or ‘solid outlet ’. 863Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Cell Z one C onditions7.2.2.1.6. Defining R adiation P aramet ers If you ar e using the DO r adia tion mo del, you c an sp ecify whether or not the solid ma terial par ticipa tes in radia tion using the Participa tes in R adia tion option. See Defining B oundar y Conditions f or R adi- ation (p.1514 ) for details . 7.2.3. Porous M edia C onditions The p orous media mo del c an b e used f or a wide v ariety of single phase and multiphase pr oblems , including flo w thr ough pack ed b eds, filter pap ers, perforated pla tes, flow distr ibut ors, and tub e banks . When y ou use this mo del, you define a c ell z one in which the p orous media mo del is applied and the pressur e loss in the flo w is det ermined via y our inputs as descr ibed in Momen tum E qua tions f or P orous Media (p.865). Heat transf er thr ough the medium c an also b e represen ted, with or without the assump- tion of ther mal equilibr ium b etween the medium and the fluid flo w (as descr ibed in Treatmen t of the Ener gy Equa tion in P orous M edia (p.867)). A 1D simplific ation of the p orous media mo del, termed the “porous jump ,” can b e used t o mo del a thin membr ane with k nown v elocity/pr essur e-dr op char acteristics .The p orous jump mo del is applied to a fac e zone , not t o a c ell z one , and should b e used (inst ead of the full p orous media mo del) whene ver p ossible b ecause it is mor e robust and yields b etter convergenc e. See Porous J ump Boundar y Conditions (p.1016 ) for details . 7.2.3.1. Limitations and Assumptions of the P orous Media Mo del The p orous media mo del inc orporates an empir ically det ermined flo w resistanc e in a r egion of y our model defined as “porous”. In essenc e, the p orous media mo del adds a momen tum sink in the go v- erning momen tum equa tions . Consequen tly, the f ollowing mo deling assumptions and limita tions should b e readily r ecogniz ed: •Since the v olume blo ckage tha t is ph ysically pr esen t is not r epresen ted in the mo del, by default ANSY S Fluen t uses and r eports a sup erficial v elocity inside the p orous medium, based on the v olumetr ic flo w rate, to ensur e continuit y of the v elocity vectors acr oss the p orous medium in terface.This sup erficial v e- locity formula tion do es not tak e porosity into acc oun t when c alcula ting the c onvection and diffusion terms of the tr ansp ort equa tions .You c an cho ose t o use a mor e accur ate alt ernative, in which the tr ue (physical) v elocity is c alcula ted inside the p orous medium and p orosity is included in the diff erential t erms of the tr ansp ort equa tions . See Modeling P orous M edia B ased on P hysical Velocity (p.869) for details . In a multiphase flo w sy stem, all phases shar e the same p orosity. •The eff ect of the p orous medium on the turbulenc e field is only appr oxima ted. See Treatmen t of Turbulenc e in Porous M edia (p.869) for details . •In gener al, the ANSY S Fluen t porous medium mo del, for b oth single phase and multiphase , assumes the porosity is isotr opic , and it c an v ary with spac e and time . •The Sup erficial Velocity Formula tion and the P hysical Velocity Formula tion ar e available f or multiphase porous media. See User Inputs f or P orous M edia (p.872) for details . •The p orous media momen tum r esistanc e and hea t sour ce terms ar e calcula ted separ ately on each phase . See Momen tum E qua tions f or P orous M edia (p.865) for details . •A unique pr essur e interpolation scheme is alw ays used inside p orous media z ones r egar dless of the pressur e scheme selec ted in the Solution M etho ds task page . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 864Cell Z one and B oundar y Conditions•The in teractions b etween a p orous medium and sho ck w aves ar e not c onsider ed. •When applying the p orous media mo del in a mo ving r eference frame , ANSY S Fluen t will either apply the relative reference frame or the absolut e reference frame when y ou enable the Rela tive Velocity Resistanc e Formula tion .This allo ws for the c orrect predic tion of the sour ce terms. •Standar d Initializa tion is the r ecommended initializa tion metho d for p orous media simula tions .The default Hybr id Initializa tion metho d do es not acc oun t for the p orous media pr operties, and dep ending on b oundar y conditions , may pr oduce an unr ealistic initial v elocity field . For p orous media simula tions , the Hybr id Initializa tion metho d can only b e used if the Maintain C onstan t Velocity M agnitude option is selec ted in the Hybr id Initializa tion dialo g box. •The ph ysical velocity porous f ormula tion ma y pr oduce non-ph ysical flo w fields and p oor c onvergenc e when p orous r esistanc e (Iner tial or Viscous) v alues ar e less than or c ompar able t o the change in the d ynamic pr essur e acr oss the p orous in terface (in terior fac e zone separ ating the p orous and non-p orous c ell z one). Switching the p orous in terface zone t o a p orous jump b oundar y is an eff ective way to overcome this issue . 7.2.3.2. Momentum E quations for P orous Media The p orous media mo dels f or single phase flo ws and multiphase flo ws use the Superficial Velocity Porous F ormula tion as the default. ANSY S Fluen t calcula tes the sup erficial phase or mix ture velocities based on the v olumetr ic flo w rate in a p orous r egion. The p orous media mo del is descr ibed in the following sec tions f or single phase flo w, however, it is imp ortant to not e the f ollowing f or multiphase flow: •In the E uler ian multiphase mo del ( Euler ian M odel Theor y in the Theor y Guide ), the gener al porous media modeling appr oach, physical la ws, and equa tions descr ibed b elow ar e applied t o the c orresponding phase for mass c ontinuit y, momen tum, ener gy, and all the other sc alar equa tions . •The Superficial Velocity Porous F ormula tion gener ally giv es go od represen tations of the bulk pr essur e loss thr ough a p orous r egion. However, sinc e the sup erficial v elocity values within a p orous r egion r emain the same as those outside the p orous r egion, it cannot pr edic t the v elocity incr ease in p orous z ones and ther efore limits the accur acy of the mo del. Porous media ar e mo deled b y the addition of a momen tum sour ce term to the standar d fluid flo w equa tions .The sour ce term is c omp osed of t wo par ts: a visc ous loss t erm (D arcy, the first t erm on the r ight-hand side of Equa tion 7.1 (p.865), and an iner tial loss t erm (the sec ond t erm on the r ight- hand side of Equa tion 7.1 (p.865)) (7.1) wher e is the sour ce term for the th ( , , or ) momen tum equa tion, is the magnitude of the velocity and and are pr escr ibed ma trices.This momen tum sink c ontribut es to the pr essur e gradien t in the p orous c ell, creating a pr essur e dr op tha t is pr oportional t o the fluid v elocity (or v elocity squar ed) in the c ell. To recover the c ase of simple homo geneous p orous media (7.2) 865Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Cell Z one C onditionswher e is the p ermeabilit y and is the iner tial r esistanc e fac tor, simply sp ecify and as diagonal matrices with and , respectively, on the diagonals (and z ero for the other elemen ts). ANSY S Fluen t also allo ws the sour ce term to be mo deled as a p ower la w of the v elocity magnitude: (7.3) wher e and are user-defined empir ical coefficien ts. Imp ortant In the p ower-la w mo del, the pr essur e dr op is isotr opic and the units f or are SI. 7.2.3.2.1. Darcy’s Law in P orous Media In laminar flo ws thr ough p orous media, the pr essur e dr op is t ypic ally pr oportional t o velocity and the c onstan t can b e consider ed t o be zero. Ignor ing c onvective acc eleration and diffusion, the porous media mo del then r educ es to Darcy’s La w: (7.4) The pr essur e dr op tha t ANSY S Fluen t comput es in each of the thr ee ( , , ) coordina te dir ections within the p orous r egion is then (7.5) wher e are the en tries in the ma trix in Equa tion 7.1 (p.865), are the v elocity comp onen ts in the , , and directions , and , , and are the thick nesses of the medium in the , , and directions . Here, the thick ness of the medium ( , , or ) is the actual thick ness of the p orous r egion in your mo del. Therefore if the thick nesses used in y our mo del diff er fr om the ac tual thick nesses , you must mak e the adjustmen ts in y our inputs f or . 7.2.3.2.2. Iner tial L osses in P orous Media At high flo w velocities , the c onstan t in Equa tion 7.1 (p.865) provides a c orrection f or iner tial losses in the p orous medium. This c onstan t can b e view ed as a loss c oefficien t per unit length along the flow dir ection, ther eby allo wing the pr essur e dr op t o be sp ecified as a func tion of d ynamic head . If you ar e mo deling a p erforated pla te or tub e bank, you c an sometimes elimina te the p ermeabilit y term and use the iner tial loss t erm alone , yielding the f ollowing simplified f orm of the p orous media equa tion: (7.6) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 866Cell Z one and B oundar y Conditionsor when wr itten in t erms of the pr essur e dr op in the , , directions: (7.7) Again, the thick ness of the medium ( , , or ) is the thick ness y ou ha ve defined in y our model. 7.2.3.3. Relativ e Visc osit y in P orous Media For visc ous flo ws, an eff ective visc osity, , is in troduced t o acc oun t for the eff ect of the p orous me- dium on the diffusion t erm in the momen tum equa tions: (7.8) wher e is the fluid visc osity and is the r elative visc osity. In F luen t the f ollowing sub-mo dels ar e implemen ted t o calcula te the r elative visc osity.The eff ective visc osity is then c alcula ted fr om Equa- tion 7.8 (p.867). Brinkman C orrection [17] (p.4005 ) (7.9) Einst ein F ormula [16] (p.4005 ) (7.10) Breugem C orrelation [15] (p.4005 ) (7.11) 7.2.3.4. Treatment of the E ner gy Equation in P orous Media ANSY S Fluen t solv es the standar d ener gy transp ort equa tion ( Equa tion 5.1 in the Theor y Guide ) in porous media r egions with mo dific ations t o the c onduc tion flux and the tr ansien t terms only . 7.2.3.4.1. Equilibrium Thermal Mo del E quations For simula tions in which the p orous medium and fluid flo w ar e assumed t o be in ther mal equilibr ium, the c onduc tion flux in the p orous medium uses an eff ective conduc tivit y and the tr ansien t term in- cludes the ther mal iner tia of the solid r egion on the medium: (7.12) wher e 867Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Cell Z one C onditions = total fluid ener gy = total solid medium ener gy = fluid densit y = solid medium densit y = p orosity of the medium = eff ective ther mal c onduc tivit y of the medium = fluid en thalp y sour ce term The eff ective ther mal c onduc tivit y in the p orous medium, , is c omput ed b y ANSY S Fluen t as the volume a verage of the fluid c onduc tivit y and the solid c onduc tivit y: (7.13) wher e = fluid phase ther mal c onduc tivit y (including the turbulen t contribution, ) = solid medium ther mal c onduc tivit y The fluid ther mal c onduc tivit y and the solid ther mal c onduc tivit y can b e comput ed via user- defined func tions . The anisotr opic eff ective ther mal c onduc tivit y can also b e sp ecified via user-defined func tions . In this c ase, the isotr opic c ontributions fr om the fluid , , are added t o the diagonal elemen ts of the solid anisotr opic ther mal c onduc tivit y ma trix. 7.2.3.4.2. Non-E quilibrium Thermal Mo del E quations For simula tions in which the p orous medium and fluid flo w ar e not assumed t o be in ther mal equi- librium, a dual c ell appr oach is used . In such an appr oach, a solid z one tha t is spa tially c oinciden t with the p orous fluid z one is defined , and this solid z one only in teracts with the fluid with r egar d to hea t transf er.The c onser vation equa tions f or ener gy are solv ed separ ately f or the fluid and solid zones .The c onser vation equa tion solv ed f or the fluid z one is (7.14) and the c onser vation equa tion solv ed f or the solid z one is (7.15) wher e = total fluid ener gy = total solid medium ener gy = fluid densit y = solid medium densit y Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 868Cell Z one and B oundar y Conditions = p orosity of the medium = fluid phase ther mal c onduc tivit y (including the turbulen t contribution, ) = solid medium ther mal c onduc tivit y = hea t transf er coefficien t for the fluid / solid in terface = in terfacial ar ea densit y, tha t is, the r atio of the ar ea of the fluid / solid in terface and the v olume of the p orous z one = temp erature of the fluid = temp erature of the solid medium = fluid en thalp y sour ce term = solid en thalp y sour ce term The fluid ther mal c onduc tivit y and the solid ther mal c onduc tivit y can b e comput ed via user- defined func tions . The sour ce term due t o the non-equilibr ium ther mal mo del is r epresen ted in Equa tion 7.14 (p.868) and Equa tion 7.15 (p.868) by and , respectively. 7.2.3.5. Treatment of Turbulenc e in P orous Media ANSY S Fluen t will, by default , solv e the standar d conser vation equa tions f or turbulenc e quan tities in the p orous medium. In this default appr oach, turbulenc e in the medium is tr eated as though the solid medium has no eff ect on the turbulenc e gener ation or dissipa tion r ates.This assumption ma y be reasonable if the medium ’s permeabilit y is quit e lar ge and the geometr ic sc ale of the medium does not in teract with the sc ale of the turbulen t eddies . In other instanc es, however, you ma y want to suppr ess the eff ect of turbulenc e in the medium. If you ar e using one of the turbulenc e mo dels (with the e xception of the Lar ge E ddy Simula tion (LES) model), you c an suppr ess the eff ect of turbulenc e in a p orous r egion b y enabling the Laminar Z one option in the Fluid D ialog Box (p.3457 ). Refer to Specifying a Laminar Z one (p.856) for details ab out using the Laminar Z one option. 7.2.3.6. Effec t of P orosit y on Transient Sc alar E quations For tr ansien t porous media c alcula tions , the eff ect of p orosity on the time-der ivative terms is acc oun ted for in all sc alar tr ansp ort equa tions and the c ontinuit y equa tion. When the eff ect of p orosity is tak en into acc oun t, the time-der ivative term b ecomes , wher e is the sc alar quan tity ( , , and so on) and is the p orosity. The eff ect of p orosity is enabled aut oma tically f or tr ansien t calcula tions , and the p orosity is set t o 1 by default. 7.2.3.7. Mo deling P orous Media B ased on P hysical Velocity As sta ted in Limita tions and A ssumptions of the P orous M edia M odel (p.864), by default ANSY S Flu- ent calcula tes the sup erficial v elocity based on v olumetr ic flo w rate.The sup erficial v elocity in the governing equa tions c an b e represen ted as 869Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Cell Z one C onditions(7.16) wher e is the p orosity of the media defined as the r atio of the v olume o ccupied b y the fluid t o the total v olume . The sup erficial v elocity values within the p orous r egion r emain the same as those outside of the porous r egion, and p orosity is not tak en in to acc oun t in the diff erential t erms of the tr ansp ort equa- tions .This limits the accur acy of the p orous mo del in c ases wher e ther e should b e an incr ease in v e- locity thr oughout the p orous r egion, and do es not yield accur ate results when v elocity values and gradien ts ar e imp ortant. For mor e accur ate simula tions of p orous media flo ws, it b ecomes nec essar y to solv e for the tr ue, or ph ysical, velocity thr oughout the flo wfield r ather than the sup erficial v elocity, as w ell as t o include p orosity in all t erms of the tr ansp ort equa tions . ANSY S Fluen t allo ws the c alcula tion of the ph ysical velocity using the Porous F ormula tion , available in the Cell Z one C onditions task page . By default , the Superficial Velocity option is tur ned on. 7.2.3.7.1. Single P hase P orous Media Using the ph ysical velocity formula tion, and assuming a gener al sc alar , the go verning equa tion in an isotr opic p orous media has the f ollowing f orm: (7.17) Assuming isotr opic p orosity and single phase flo w, the v olume-a veraged mass and momen tum conser vation equa tions ar e as f ollows: (7.18) (7.19) The last t erm in Equa tion 7.19 (p.870) represen ts the visc ous and iner tial dr ag f orces imp osed b y the pore walls on the fluid . Imp ortant Note tha t even when y ou solv e for the ph ysical velocity in Equa tion 7.19 (p.870), the t wo resistanc e coefficien ts can still b e der ived using the sup erficial v elocity as giv en in Defining the Viscous and Iner tial R esistanc e Coefficien ts (p.876). ANSY S Fluen t assumes tha t the inputs f or these r esistanc e coefficien ts ar e based up on w ell-established empir ical correla- tions tha t are usually based on sup erficial v elocity.Therefore, ANSY S Fluen t aut oma tically converts the inputs f or the r esistanc e coefficien ts in to those tha t are compa tible with the physical velocity formula tion. Imp ortant Note tha t the inlet mass flo w is also c alcula ted fr om the sup erficial v elocity.Therefore, for the same mass flo w rate at the inlet and the same r esistanc e coefficien ts, for either the ph ysical or sup erficial v elocity formula tion y ou should obtain the same pr essur e dr op across the p orous media z one . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 870Cell Z one and B oundar y Conditions7.2.3.7.2. Multiphase P orous Media You c an simula te porous media multiphase flo ws using the Physical Velocity Porous F ormula tion to solv e the tr ue or ph ysical velocity field thr oughout the en tire flo w field , including b oth p orous and non-p orous r egions . In this appr oach, assuming a gener al sc alar in the phase , , the go v- erning equa tion in an isotr opic p orous medium tak es on the f ollowing f orm: (7.20) Here is the p orosity, which ma y vary with time and spac e; is the phase densit y; is the v olume fraction; is the phase v elocity vector; is the sour ce term; and is the diffusion c oefficien t. The gener al sc alar equa tion Equa tion 7.20 (p.871) applies t o all other tr ansp ort equa tions in the E u- lerian multiphase mo del, such as the gr anular phase momen tum and ener gy equa tions , turbulenc e modeling equa tions , and the sp ecies tr ansp ort equa tions . Assuming isotr opic p orosity and multiphase flo ws, the go verning equa tions in the phase ,Equa- tion 18.175 ,Equa tion 18.176 , and Equa tion 18.179 in the Theor y Guide tak e the gener al forms descr ibed below. 7.2.3.7.2.1. The C ontinuit y Equation (7.21) 7.2.3.7.2.2. The Momentum E quation (7.22) wher e is c apillar y pr essur e for the w etting phase , is phase shear str ess, is the b ody force, and are the mass tr ansf ers fr om phase to phase and vic e versa, is the absolut e per- meabilit y, and is the r elative permeabilit y.The t erm in the br ackets is the p orous sink, having zero value in non-p orous flo ws/regions .The last t wo terms includes the gener al in terphase momen tum exchange f orces: is the dr ag f orce for non-p orous flo ws/regions , is the turbulen t disp ersed force, and are the r elative velocity vectors, and , , and are the e xternal b ody, lift and vir tual mass e xchange f orces. If the c apillar y pr essur e mo del is not enabled , =1. Details ab out the user inputs r elated t o the momen tum r esistanc e sour ces c an b e found in User Inputs for P orous M edia (p.872). 871Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Cell Z one C onditions7.2.3.7.2.3. The E ner gy Equation (7.23) wher e: Subscr ipts , , and denot e phase , phase , and the solid ma terial, respectively is the t otal en thalp y is the ther mal c onduc tivit y is the hea t transf er b etween phase and phase is the densit y is the hea t sour ce is the phase v olume fr action is the phase v elocity and are the t otal en thalp y diff erences b etween phases and and vic e versa 7.2.3.8. User Inputs for P orous Media When y ou ar e mo deling a p orous r egion, the additional inputs f or the pr oblem setup ar e as f ollows. Optional inputs ar e indic ated as such. 1.Define the p orous z one (as descr ibed in Defining the P orous Z one (p.874)). 2.(optional) D efine the p orous v elocity formula tion in the Cell Z one C onditions task page (as descr ibed in Defining the P orous Velocity Formula tion (p.874)). 3.Iden tify the fluid ma terial flo wing thr ough the p orous medium (as descr ibed in Defining the F luid P assing Through the P orous M edium (p.875)). 4.Enable r eactions f or the p orous z one , if appr opriate, and selec t the r eaction mechanism (as descr ibed in Enabling R eactions in a P orous Z one (p.875)). 5.Enable the Rela tive Velocity Resistanc e Formula tion . By default , this option is alr eady enabled and takes the mo ving p orous media in to consider ation (as descr ibed in Including the R elative Velocity Res- istanc e Formula tion (p.875)). 6.Set the visc ous r esistanc e coefficien ts ( in Equa tion 7.1 (p.865), or in Equa tion 7.2 (p.865)) and the iner tial r esistanc e coefficien ts ( in Equa tion 7.1 (p.865), or in Equa tion 7.2 (p.865)), and define the dir ection v ectors f or which the y apply . Alternatively, specify the c oefficien ts for the p ower-la w model. (See Defining the Viscous and Iner tial R esistanc e Coefficien ts (p.876) for mor e details .) 7.Specify the p orosity of the p orous medium (as descr ibed in Defining P orosity (p.883)). 8.(optional) S pecify the settings f or hea t transf er (as descr ibed in Specifying the H eat Transf er Set- tings (p.883)). 9.(optional) S pecify a mo del f or relative visc osity (as descr ibed in Specifying the R elative Viscosity (p.886)). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 872Cell Z one and B oundar y Conditions10.(optional, Euler ian multiphase mo dels only) S pecify r elative permeabilit y (as descr ibed in Specifying the Relative Permeabilit y (p.886). 11.(optional) S et the v olumetr ic hea t gener ation r ate in the non-solid p ortion of the p orous medium (or any other sour ces, such as mass or momen tum). (See Defining S ources (p.897) for mor e details .) 12.(optional) S et an y fix ed v alues f or solution v ariables in the fluid r egion (as descr ibed in Defining F ixed Values (p.897). 13.Suppr ess the turbulen t visc osity in the p orous r egion, if appr opriate. (See Suppr essing the Turbulen t Viscosity in the P orous R egion (p.897) for mor e details .) 14.Specify the r otation axis and/or z one motion, if relevant. (See Specifying the R otation A xis and D efining Zone M otion (p.898) for mor e details .) Metho ds for det ermining the r esistanc e coefficien ts and/or p ermeabilit y are pr esen ted b elow. If you choose t o use the p ower-la w appr oxima tion of the p orous-media momen tum sour ce term, you will enter the c oefficien ts and in Equa tion 7.3 (p.866) inst ead of the r esistanc e coefficien ts and flo w direction. You will set all par amet ers f or the p orous medium in the Fluid D ialog Box (p.3457 ) (Figur e 7.19: The Fluid D ialog Box for a P orous Z one (p.874)), which is op ened fr om the Cell Z one C onditions task page (as descr ibed in Setting C ell Z one and B oundar y Conditions (p.839)). 873Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Cell Z one C onditionsFigur e 7.19: The F luid D ialo g Box for a P orous Z one 7.2.3.8.1. Defining the P orous Z one As men tioned in Overview (p.835), a p orous z one is mo deled as a sp ecial t ype of fluid z one .To in- dicate tha t the fluid z one is a p orous r egion, enable the Porous Z one option in the Fluid dialo g box.The dialo g box will e xpand t o sho w the p orous media inputs (as sho wn in Figur e 7.19: The Fluid D ialog Box for a P orous Z one (p.874)). In a c oupled analy sis in volving F luen t and S ystem C oupling , a p orous jump b oundar y of z ero-thick ness next to the p orous z one c an b e used t o transf er da ta b etween the p orous z one and the S ystem Coupling sy stem. For mor e ab out S ystem C oupling and the v ariable tr ansf erred fr om a p orous jump boundar y, see Performing S ystem C oupling S imula tions U sing F luen t (p.3207 ). 7.2.3.8.2. Defining the P orous Velocity Formulation The Cell Z one C onditions task page c ontains a Porous F ormula tion region wher e you c an instr uct ANSY S Fluen t to use either a sup erficial or ph ysical velocity in the p orous medium simula tion. By default , the v elocity is set t o Superficial Velocity. For details ab out using the Physical Velocity formula tion, see Modeling P orous M edia B ased on P hysical Velocity (p.869). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 874Cell Z one and B oundar y Conditions7.2.3.8.3. Defining the F luid P assing Through the P orous Medium To define the fluid tha t passes thr ough the p orous medium, selec t the appr opriate fluid in the Ma- terial N ame drop-do wn list in the Fluid D ialog Box (p.3457 ). If you w ant to check or mo dify the properties of the selec ted ma terial, you c an click Edit... to op en the Edit M aterial dialo g box; this dialo g box contains just the pr operties of the selec ted ma terial, not the full c ontents of the standar d Create/Edit M aterials dialo g box. Imp ortant If you ar e mo deling sp ecies tr ansp ort or multiphase flo w, the Material N ame list will not app ear in the Fluid dialo g box. For sp ecies c alcula tions , the mix ture ma terial for all flu- id/p orous z ones will b e the ma terial y ou sp ecified in the Species M odel D ialog Box (p.3294 ). For multiphase flo ws, the ma terials ar e sp ecified when y ou define the phases , as descr ibed in Defining the P hases f or the VOF M odel (p.2171 ). 7.2.3.8.4. Enabling R eac tions in a P orous Z one If you ar e mo deling sp ecies tr ansp ort with r eactions , you c an enable r eactions in a p orous z one b y turning on the Reac tion option in the Fluid dialo g box and selec ting a mechanism in the Reac tion Mechanism drop-do wn list. If your mechanism c ontains w all sur face reactions , you also must sp ecify a v alue f or the Surface-to- Volume R atio.This v alue is the sur face ar ea of the p ore walls p er unit v olume ( ), and c an b e though t of as a measur e of c atalyst loading .With this v alue , ANSY S Fluen t can c alcula te the t otal surface ar ea on which the r eaction tak es plac e in each c ell b y multiplying by the v olume of the cell and the p orosity. See Defining Z one-B ased R eaction M echanisms (p.1642 ) for details ab out defining reaction mechanisms . See Wall Sur face Reactions and C hemic al Vapor D eposition (p.1654 ) for details about w all sur face reactions . Note The w all sur face reactions in p orous medium ar e allo wed only f or the pr essur e-based solv er. 7.2.3.8.5. Including the R elativ e Velocity Resistanc e Formulation For c ases in volving mo ving meshes , dynamic meshes or mo ving r eference frames (MRF), the Rela tive Velocity Resistanc e Formula tion option allo ws you t o better pr edic t porous media sour ces.The porous media sour ce terms ar e calcula ted using r elative velocities in the p orous z one . For mor e in- formation, see Momen tum E qua tions f or P orous M edia (p.865).The Rela tive Velocity Resistanc e Formula tion option w orks w ell for c ases with mo ving and sta tionar y porous media. It is tur ned on by default. Note the f ollowing limita tion when using the Rela tive Velocity Resistanc e Formula tion option: 875Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Cell Z one C onditions•The r elative velocity resistanc e formula tion is not supp orted with axisymmetr ic-swir l when ther e are non-z ero swir l resistanc es. Note In ANSY S Fluen t 6.3, this option w as only supp orted f or mo ving mesh and MRF (with the exception of p ower la w for mo deling p orous sour ces). Currently, this option also supp orts dynamic mesh and tak es c are of pr oper tr eatmen t of p orous sour ces using p ower la w. 7.2.3.8.6. Defining the Visc ous and Iner tial R esistanc e Coefficients The visc ous and iner tial r esistanc e coefficien ts ar e both defined in the same manner .The basic ap- proach f or defining the c oefficien ts using a C artesian c oordina te sy stem is t o define one dir ection vector in 2D or t wo dir ection v ectors in 3D , and then sp ecify the visc ous and/or iner tial r esistanc e coefficien ts in each dir ection. In 2D , the sec ond dir ection, which is not e xplicitly defined , is nor mal to the plane defined b y the sp ecified dir ection v ector and the direction v ector. In 3D , the thir d direction is nor mal t o the plane defined b y the t wo sp ecified dir ection v ectors. For a 3D pr oblem, the sec ond dir ection must b e nor mal t o the first. If you fail t o sp ecify t wo nor mal dir ections , the solv er will ensur e tha t the y are nor mal b y ignor ing an y comp onen t of the sec ond dir ection tha t is in the first dir ection. You should ther efore be certain tha t the first dir ection is c orrectly sp ecified . You c an also define the visc ous and/or iner tial r esistanc e coefficien ts in each dir ection using a user- defined func tion (UDF). The user-defined options b ecome a vailable in the c orresponding dr op-do wn list when the UDF has b een cr eated and loaded in to ANSY S Fluen t. Note tha t the c oefficien ts defined in the UDF must utiliz e the DEFINE_PROFILE macr o. For mor e inf ormation on cr eating and using user-defined func tion, see the Fluen t Customiza tion M anual . If you ar e mo deling axisymmetr ic swir ling flo ws, you c an sp ecify an additional dir ection c omp onen t for the visc ous and/or iner tial r esistanc e coefficien ts.This dir ection c omp onen t is alw ays tangen tial to the other t wo sp ecified dir ections .This option is a vailable f or b oth densit y-based and pr essur e- based solv ers. In 3D , it is also p ossible t o define the c oefficien ts using a c onic al (or c ylindr ical) c oordina te sy stem, as descr ibed b elow. Imp ortant Note tha t the visc ous and iner tial r esistanc e coefficien ts ar e gener ally based on the sup er- ficial v elocity of the fluid in the p orous media. The pr ocedur e for defining r esistanc e coefficien ts is as f ollows: 1.Define the dir ection v ectors. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 876Cell Z one and B oundar y Conditions•To use a C artesian c oordina te sy stem, simply sp ecify the Direction-1 Vector and , for 3D , the Direction- 2 Vector.The unsp ecified dir ection will b e det ermined as descr ibed ab ove.These dir ection v ectors correspond t o the pr inciple ax es of the p orous media. Note The units f or the iner tial r esistanc e coefficien ts (Direction-1 Vector and Direction- 2 Vector) is the in verse of length. Should y ou w ant to define diff erent units , you can do so b y op ening the Units dialo g box and selec ting resistanc e from the Quan tities list. For some pr oblems in which the pr incipal ax es of the p orous medium ar e not aligned with the c oordina te ax es of the domain, you ma y not k now a pr iori the dir ection v ectors of the porous medium. In such c ases , the plane t ool in 3D (or the line t ool in 2D) c an help y ou t o determine these dir ection v ectors. a.“Snap” the plane t ool (or the line t ool) on to the b oundar y of the p orous r egion. (Follow the in- structions in Using the P lane Tool (p.2744 ) or Using the Line Tool (p.2740 ) for initializing the t ool to a position on an e xisting sur face.) b.Rotate the ax es of the t ool appr opriately un til the y are aligned with the p orous medium. c.Onc e the ax es ar e aligned , click the Update From P lane Tool or Update From Line Tool butt on in the Fluid dialo g box. ANSY S Fluen t will aut oma tically set the Direction-1 Vector to the dir ection of the r ed ar row of the t ool, and (in 3D) the Direction-2 Vector to the dir ection of the gr een ar row. •To use a c onic al coordina te sy stem (f or e xample , for an annular , conic al filt er elemen t), follow the steps b elow.This option is a vailable only in 3D c ases . a.Turn on the Conic al option. b.Set the Cone H alf A ngle (the angle b etween the c one’s axis and its sur face, sho wn in Fig- ure 7.20: Cone Half A ngle (p.877)).To use a c ylindr ical coordina te sy stem, set the Cone H alf A ngle to 0. c.Specify the Cone A xis Vector and Point on C one A xis.The c one axis is sp ecified as b eing in the direction of the Cone A xis Vector (unit v ector), and passing thr ough the Point on C one A xis. The c one axis ma y or ma y not pass thr ough the or igin of the c oordina te sy stem. Figur e 7.20: Cone H alf A ngle For some pr oblems in which the axis of the c onic al filt er elemen t is not aligned with the c o- ordina te ax es of the domain, you ma y not k now a pr iori the dir ection v ector of the c one axis and c oordina tes of a p oint on the c one axis . In such c ases , the plane t ool can help y ou t o de- termine the c one axis v ector and p oint coordina tes. One metho d is as f ollows: 877Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Cell Z one C onditionsa.Selec t a b oundar y zone of the c onic al filt er elemen t tha t is nor mal t o the c one axis v ector in the drop-do wn list ne xt to the Snap t o Zone butt on. b.Click the Snap t o Zone butt on. ANSY S Fluen t will aut oma tically “snap ” the plane t ool on to the boundar y. It will also set the Cone A xis Vector and the Point on C one A xis. (Note tha t you will still ha ve to set the Cone H alf A ngle yourself .) An alt ernate metho d is as f ollows: a.“Snap” the plane t ool on to the b oundar y of the p orous r egion. (Follow the instr uctions in Using the P lane Tool (p.2744 ) for initializing the t ool to a p osition on an e xisting sur face.) b.Rotate and tr ansla te the ax es of the t ool appr opriately un til the r ed ar row of the t ool is p ointing in the dir ection of the c one axis v ector and the or igin of the t ool is on the c one axis . c.Onc e the ax es and or igin of the t ool ar e aligned , click the Update From P lane Tool butt on in the Fluid dialo g box. ANSY S Fluen t will aut oma tically set the Cone A xis Vector and the Point on Cone A xis. (Note tha t you will still ha ve to set the Cone H alf A ngle yourself .) 2.Under Visc ous Resistanc e, specify the visc ous r esistanc e coefficien t in each dir ection. Under Iner tial Resistanc e, specify the iner tial r esistanc e coefficien t in each dir ection. (You can scr oll do wn with the scr oll bar t o view these inputs .) For p orous media c ases c ontaining highly anisotr opic iner tial r esistanc es, enable Alternative Formula tion under Iner tial Resistanc e.The Alternative Formula tion option pr ovides b etter stabilit y to the c alcula tion when y our p orous medium is anisotr opic .The pr essur e loss thr ough the medium dep ends on the magnitude of the v elocity vector of the ith comp onen t in the medium. Using the f ormula tion of Equa tion 7.6 (p.866) yields the e xpression b elow: (7.24) Whether or not y ou use the Alternative Formula tion option dep ends on ho w w ell y ou c an fit your e xperimen tally det ermined pr essur e dr op da ta to the ANSY S Fluen t mo del. For e xample , if the flo w thr ough the medium is aligned with the mesh in y our ANSY S Fluen t mo del, then it will not mak e a diff erence whether or not y ou use the f ormula tion. In gener al, however, the default and the Alternative Formula tion are not equiv alen t, and solution diff erences c an o ccur when swit ching b etween the t wo options . For mor e inf ormation ab out simula tions in volving highly anisotr opic p orous media, see Solution Strategies f or P orous M edia (p.898). Imp ortant Note tha t the alt ernative formula tion is c ompa tible only with the pr essur e-based solv er. If you ar e using the Conic al specific ation metho d,Direction-1 is the tangen tial dir ection of the cone ,Direction-2 is the nor mal t o the c one sur face (radial ( ) dir ection f or a c ylinder), and Dir- ection-3 is the cir cumf erential ( ) dir ection. In 3D ther e ar e thr ee p ossible c ategor ies of c oefficien ts, and in 2D ther e ar e two: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 878Cell Z one and B oundar y Conditions•In the isotr opic c ase, the r esistanc e coefficien ts in all dir ections ar e the same (f or e xample , a sp onge). For an isotr opic c ase, you must e xplicitly set the r esistanc e coefficien ts in each dir ection t o the same value . •When (in 3D) the c oefficien ts in t wo dir ections ar e the same and those in the thir d dir ection ar e dif- ferent or (in 2D) the c oefficien ts in the t wo dir ections ar e diff erent, you must b e careful t o sp ecify the coefficien ts pr operly for each dir ection. For e xample , if you had a p orous r egion c onsisting of c ylindr ical straws with small holes in them p ositioned par allel t o the flo w dir ection, the flo w w ould pass easily through the str aws, but the flo w in the other t wo dir ections (thr ough the small holes) w ould b e very little . If you had a plane of fla t pla tes p erpendicular t o the flo w dir ection, the flo w w ould not pass through them a t all; it w ould inst ead mo ve in the other t wo dir ections . •In 3D the thir d possible c ase is one in which all thr ee c oefficien ts ar e diff erent. For e xample , if the porous r egion c onsist ed of a plane of ir regular ly-spac ed objec ts (for e xample , pins), the mo vemen t of flo w between the blo ckages w ould b e diff erent in each dir ection. You w ould ther efore need t o specify diff erent coefficien ts in each dir ection. Metho ds for der iving visc ous and iner tial loss c oefficien ts ar e descr ibed in the sec tions tha t follow. 7.2.3.8.7. Deriving P orous Media Inputs B ased on S uperficial Velocity, Using a K nown Pressur e Loss When y ou use the p orous media mo del, you must r ememb er tha t the p orous c ells in ANSY S Fluen t are 100% op en, and tha t the v alues tha t you sp ecify f or and/or must b e based on this assumption. Supp ose, however, tha t you k now ho w the pr essur e dr op v aries with the v elocity thr ough the ac tual de vice, which is only par tially op en t o flo w.The f ollowing e xercise is designed t o sho w you ho w to comput e a v alue f or which is appr opriate for the ANSY S Fluen t mo del. Consider a p erforated pla te tha t has 25% ar ea op en t o flo w.The pr essur e dr op thr ough the pla te is known t o be 0.5 times the d ynamic head in the pla te.The loss fac tor, , defined as (7.25) is ther efore 0.5, based on the ac tual fluid v elocity in the pla te, tha t is, the v elocity thr ough the 25% open ar ea.To comput e an appr opriate value f or , not e tha t in the ANSY S Fluen t mo del: 1.The v elocity thr ough the p erforated pla te assumes tha t the pla te is 100% op en. 2.The loss c oefficien t must b e converted in to dynamic head loss p er unit length of the p orous r egion. Noting it em 1, the first st ep is t o comput e an adjust ed loss fac tor, , which w ould b e based on the velocity of a 100% op en ar ea: (7.26) or, noting tha t for the same flo w rate, , (7.27) The adjust ed loss fac tor has a v alue of 8. Noting it em 2, you must no w convert this in to a loss coefficien t per unit thick ness of the p erforated pla te. Assume tha t the pla te has a thick ness of 1.0 mm ( m). The iner tial loss fac tor w ould then b e 879Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Cell Z one C onditions(7.28) Note tha t, for anisotr opic media, this inf ormation must b e comput ed f or each of the 2 (or 3) c oordina te directions . 7.2.3.8.8. Using the E rgun E quation t o D eriv e Porous Media Inputs for a P ack ed B ed As a sec ond e xample , consider the mo deling of a pack ed b ed. In turbulen t flo ws, pack ed b eds ar e modeled using b oth a p ermeabilit y and an iner tial loss c oefficien t. One t echnique f or der iving the appr opriate constan ts in volves the use of the E rgun equa tion [31] (p.4006 ), a semi-empir ical correlation applic able o ver a wide r ange of R eynolds numb ers and f or man y types of pack ing: (7.29) When mo deling laminar flo w thr ough a pack ed b ed, the sec ond t erm in the ab ove equa tion ma y be dr opp ed, resulting in the B lake-Kozeny equa tion [31] (p.4006 ): (7.30) In these equa tions , is the visc osity, is the mean par ticle diamet er, is the b ed depth, and is the v oid fr action, defined as the v olume of v oids divided b y the v olume of the pack ed b ed r egion. Compar ing Equa tion 7.4 (p.866) and Equa tion 7.6 (p.866) with Equa tion 7.29 (p.880), the p ermeabilit y and iner tial loss c oefficien t in each c omp onen t dir ection ma y be iden tified as (7.31) and (7.32) 7.2.3.8.9. Using an E mpiric al E quation t o D eriv e Porous Media Inputs for Turbulent F low Through a P erforated P late As a thir d example w e will tak e the equa tion of Van Winkle et al. [91] (p.4010 )[122] (p.4011 ) and sho w how p orous media inputs c an b e calcula ted f or pr essur e loss thr ough a p erforated pla te with squar e- edged holes . The e xpression, which is claimed b y the authors t o apply f or turbulen t flo w thr ough squar e-edged holes on an equila teral tr iangular spacing , is (7.33) wher e = mass flo w rate thr ough the pla te = the fr ee ar ea or t otal ar ea of the holes = the ar ea of the pla te (solid and holes) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 880Cell Z one and B oundar y Conditions = a c oefficien t tha t has b een tabula ted f or v arious R eynolds-numb er ranges and f or various = the r atio of hole diamet er to pla te thick ness for and f or the c oefficien t tak es a v alue of appr oxima tely 0.98, wher e the Reynolds numb er is based on hole diamet er and v elocity in the holes . Rearranging Equa tion 7.33 (p.880), mak ing use of the r elationship (7.34) and dividing b y the pla te thick ness , , we obtain (7.35) wher e is the sup erficial v elocity (not the v elocity in the holes). Compar ing with Equa tion 7.6 (p.866) is seen tha t, for the dir ection nor mal t o the pla te, the c onstan t can b e calcula ted fr om (7.36) 7.2.3.8.10. Using Tabulat ed D ata t o Deriv e Porous Media Inputs for L aminar F low Through a Fibrous M at Consider the pr oblem of laminar flo w thr ough a ma t or filt er pad which is made up of r andomly- oriented fib ers of glass w ool. As an alt ernative to the B lake-Kozeny equa tion ( Equa tion 7.30 (p.880)) we migh t cho ose t o emplo y tabula ted e xperimen tal da ta. Such da ta is a vailable f or man y types of fiber [52] (p.4007 ). Dimensionless P ermeabilit y of G lass Wool Volume F raction of S olid M aterial 0.25 0.262 0.26 0.258 0.40 0.221 0.41 0.218 0.80 0.172 wher e and is the fib er diamet er. , for use in Equa tion 7.4 (p.866), is easily c omput ed f or a giv en fib er diamet er and v olume fr action. 7.2.3.8.11. Deriving the P orous C oefficients B ased on E xperimental P ressur e and Velocity Data Experimen tal da ta tha t is a vailable in the f orm of pr essur e dr op against v elocity thr ough the p orous comp onen t, can b e extrapolated t o det ermine the c oefficien ts for the p orous media. To eff ect a pressur e dr op acr oss a p orous medium of thick ness , , the c oefficien ts of the p orous media ar e determined in the manner descr ibed b elow. If the e xperimen tal da ta is: 881Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Cell Z one C onditionsPressur e D rop (P a) Velocity (m/s) 197.8 20.0 948.1 50.0 2102.5 80.0 3832.9 110.0 then an cur ve can b e plott ed t o cr eate a tr endline thr ough these p oints yielding the f ollowing equa tion (7.37) wher e is the pr essur e dr op and is the v elocity. Imp ortant Although the b est fit cur ve ma y yield nega tive coefficien ts, it should b e avoided when using the p orous media mo del in ANSY S Fluen t. Note tha t a simplified v ersion of the momen tum equa tion, relating the pr essur e dr op t o the sour ce term, can b e expressed as (7.38) or (7.39) Hence, compar ing Equa tion 7.37 (p.882) to Equa tion 7.2 (p.865), yields the f ollowing cur ve coefficien ts: (7.40) with kg/ , and a p orous media thick ness , , assumed t o be 1 m in this e xample , the iner tial r esistanc e fac tor, . Likewise , (7.41) with , the visc ous iner tial r esistanc e fac tor, . Imp ortant Note tha t this same t echnique c an b e applied t o the p orous jump b oundar y condition. Similar t o the c ase of the p orous media, you ha ve to tak e in to acc oun t the thick ness of the medium .Your e xperimen tal da ta can b e plott ed in an cur ve, yielding an equa tion tha t is equiv alen t to Equa tion 7.145 (p.1016 ). From ther e, you c an det ermine the permeabilit y and the pr essur e jump c oefficien t . 7.2.3.8.12. Using the P ower-Law Mo del If you cho ose t o use the p ower-la w appr oxima tion of the p orous-media momen tum sour ce term (Equa tion 7.3 (p.866)), the only inputs r equir ed ar e the c oefficien ts and . Under Power L aw Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 882Cell Z one and B oundar y ConditionsModel in the Fluid dialo g box, enter the v alues f or C0 and C1. Note tha t the p ower-la w mo del c an be used in c onjunc tion with the D arcy and iner tia mo dels . C0 must b e in SI units , consist ent with the v alue of C1. 7.2.3.8.13. Defining P orosit y To define the p orosity, scroll do wn b elow the r esistanc e inputs in the Fluid dialo g box, and set the Porosit y under Fluid P orosit y. Note tha t the v alue of the Porosit y must b e in the r ange of 0–1; further mor e, the lo wer and upp er limits (tha t is,0 and 1, respectively) ar e not allo wed f or the non- equilibr ium ther mal mo del. You c an also define the p orosity using a user-defined func tion (UDF). The user-defined option b ecomes available in the c orresponding dr op-do wn list when the UDF has b een cr eated and loaded in to ANSY S Fluen t. Note tha t the p orosity defined in the UDF must utiliz e the DEFINE_PROFILE macr o. For mor e inf ormation on cr eating and using user-defined func tions , see the separ ate Fluen t Customiza tion Manual . The p orosity, , is the v olume fr action of fluid within the p orous r egion (tha t is, the op en v olume fraction of the medium). The p orosity is used in the pr edic tion of hea t transf er in the medium, as descr ibed in Treatmen t of the Ener gy Equa tion in P orous M edia (p.867), and in the time-der ivative term in the sc alar tr ansp ort equa tions f or unst eady flo w, as descr ibed in Effect of P orosity on Transien t Scalar E qua tions (p.869). It also impac ts the c alcula tion of r eaction sour ce terms and b ody forces in the medium. These sour ces will b e pr oportional t o the fluid v olume in the medium. If you w ant to represen t the medium as c omplet ely op en (no eff ect of the solid medium), you should set the porosity equal t o 1.0 (the default). When the p orosity is equal t o 1.0, the solid p ortion of the medium will ha ve no impac t on hea t transf er or ther mal/r eaction sour ce terms in the medium. 7.2.3.8.14. Specifying the H eat Transfer S ettings You c an mo del hea t transf er in the p orous ma terial, with or without the assumption of ther mal equilibr ium b etween the medium and the fluid flo w. Note tha t hea t transf er is not a vailable f or in- viscid flo w. 7.2.3.8.14.1. Equilibrium Thermal Mo del To sp ecify tha t the p orous medium and the fluid flo w ar e in ther mal equilibr ium, scroll do wn b elow the r esistanc e inputs in the Fluid dialo g box to the Heat Transf er S ettings group b ox and selec t Equilibr ium from the Thermal M odel list (this is the default selec tion). Then y ou must sp ecify the material c ontained in the p orous medium b y selec ting the appr opriate solid in the Solid M aterial Name drop-do wn list. If you w ant to check or mo dify the pr operties of the selec ted ma terial, you c an click Edit... to op en the Edit M aterial dialo g box; this dialo g box contains just the pr operties of the selec ted ma terial, not the full c ontents of the standar d Create/Edit M aterials dialo g box.You c an define the Thermal Conduc tivit y of the p orous ma terial using a user-defined func tion (UDF), in or der t o define a non- isotr opic ther mal c onduc tivit y.The user-defined option b ecomes a vailable in the c orresponding drop-do wn list when the UDF has b een cr eated and loaded in to ANSY S Fluen t. Note tha t the non- isotr opic ther mal c onduc tivit y defined in the UDF must utiliz e the DEFINE_PROPERTY macr o. For mor e inf ormation on cr eating and using user-defined func tion, see the separ ate Fluen t Customiza tion Manual . 883Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Cell Z one C onditions7.2.3.8.14.2. Non-E quilibrium Thermal Mo del Note The non-equilibr ium ther mal mo del is inc ompa tible with the densit y based solv er. The assumption of ther mal equilibr ium b etween the solid medium and the fluid flo w is not appr o- priate for all simula tions , as the pr esenc e of diff erent geometr ic length sc ales (f or e xample , pore sizes) and ph ysical pr operties of solid and liquid phases ma y result in lo cal temp erature diff erences between the phases . Examples of when a non-equilibr ium ther mal mo del ma y be suitable include the simula tion of ligh t-off f or e xhaust af ter-tr eatmen t, fuel c ells, catalytic c onverters, and so on. The non-equilibr ium ther mal mo del a vailable f or p orous media in ANSY S Fluen t is based on a dual cell appr oach. This appr oach is r eferred t o as “dual c ell” because it in volves a sec ond solid c ell z one that overlaps (tha t is, is spa tially c oinciden t with) the p orous fluid z one; the t wo zones ar e solv ed simultaneously and ar e coupled only thr ough hea t transf er. ANSY S Fluen t can aut oma tically cr eate a solid z one f or y ou tha t is a duplic ate of the p orous fluid z one; other wise , you c an cr eate a duplic ate cell z one manually using the mesh/modify-zones/copy-move-cell-zone text command before you enable the non-equilibr ium ther mal mo del, or mak e sur e tha t the mesh y ou r ead c ontains two cell z ones in the r egion wher e the p orous medium will b e defined .You should ensur e tha t the duplic ate zone is defined as a solid z one , and tha t the t wo zones ha ve similar le vels of mesh r efine- men t (as one-t o-one mapping will b e emplo yed b etween the c ell c entroids of the fluid z one and the solid z one). Imp ortant When setting up b oth the p orous fluid z one and the o verlapping solid z one , not e tha t the non-equilibr ium ther mal mo del is not supp orted f or z ones tha t under go (or ar e adja- cent to zones tha t under go) changes t o the geometr y or mesh, such as d ynamic mesh zones or z ones tha t under go hanging no de adaption, utiliz e the mesh mor pher/optimiz er, or ar e involved in fluid-str ucture in teraction (FSI) applic ations . The instr uctions tha t follow assume y ou ha ve alr eady performed st eps 1–7 in User Inputs f or P orous Media (p.872). Before you enable the non-equilibr ium ther mal mo del, click OK in the Fluid dialo g box, in or der t o sa ve your settings in the Porous Z one tab; not e tha t if y ou do not sa ve your settings , they will b e reset t o the default v alues when y ou enable the non-equilibr ium ther mal mo del. Then reop en the Fluid dialo g box and scr oll do wn b elow the r esistanc e inputs in the Porous Z one tab . Selec t Non-E quilibr ium from the Thermal M odel list in the Heat Transf er S ettings group b ox (see Figur e 7.21: The H eat Transf er S ettings G roup B ox of the F luid D ialog Box (p.885)); this will enable the dual c ell appr oach and displa y the asso ciated GUI input c ontrols. If a solid z one tha t is spa tially coinciden t with the p orous fluid z one do es not alr eady exist, use the Question dialo g box tha t op ens to aut oma tically cr eate one .The name of the newly cr eated solid c ell z one will then b e displa yed in the Solid Z one text box of the Fluid dialo g box. Imp ortant Note tha t the Non-E quilibr ium option butt on is not a vailable if a r adia tion and/or mul- tiphase mo del is enabled , as such a c ombina tion is not supp orted. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 884Cell Z one and B oundar y ConditionsFigur e 7.21: The H eat Transf er S ettings G roup B ox of the F luid D ialo g Box Next, define and (as descr ibed in Non-E quilibr ium Thermal M odel E qua tions (p.868)) for Inter- facial A rea D ensit y and Heat Transf er C oefficien t, respectively; you c an define these settings as a Constan t, a New Input P aramet er..., or as a user-defined func tion. The user-defined option b e- comes a vailable in the c orresponding dr op-do wn list when the UDF has b een cr eated and loaded into ANSY S Fluen t. Note tha t the UDF must utiliz e the DEFINE_PROFILE macr o. For mor e inf orm- ation on cr eating and using user-defined func tions , see the separ ate Fluen t Customiza tion M anual . When y ou ar e finished setting up the p orous fluid z one , you should v erify tha t the solid z one cr eated in the pr evious st ep has the appr opriate settings . Note the name of the z one displa yed in the Solid Zone text box of the Heat Transf er S ettings group b ox (see Figur e 7.21: The H eat Transf er S ettings Group B ox of the F luid D ialog Box (p.885)), and then double-click tha t zone in the Zone list of the Cell Z one C onditions task page t o op en the Solid dialo g box.Then, verify tha t an appr opriate se- lection is made f or Material N ame . If you w ant to check or mo dify the pr operties of the selec ted material, you c an click Edit... to op en the Edit M aterial dialo g box; this dialo g box contains just the properties of the selec ted ma terial, not the full c ontents of the standar d Create/Edit M aterials dialo g box.You c an define the Thermal C onduc tivit y of the solid ma terial using a user-defined func tion (UDF), in or der t o define a non-isotr opic ther mal c onduc tivit y.The user-defined option b ecomes available in the c orresponding dr op-do wn list when the UDF has b een cr eated and loaded in to ANSY S Fluen t. Note tha t the non-isotr opic ther mal c onduc tivit y defined in the UDF must utiliz e the DEFINE_PROPERTY macr o. For mor e inf ormation on cr eating and using user-defined func tions , see the separ ate Fluen t Customiza tion M anual . 885Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Cell Z one C onditionsNote tha t when p ostpr ocessing simula tions tha t utiliz e the non-equilibr ium ther mal mo del, you c an displa y the ener gy sour ce due t o the t emp erature diff erence between the fluid and solid z ones using the Non-E quilibr ium Thermal M odel S our ce variable in the Temp erature... categor y. Further mor e, attention must b e paid t o the fac t tha t ther e ar e overlapping c ell z ones (tha t is, a fluid and a solid zone) in the p orous r egion. For e xample: •When cr eating an isosur face and mak ing selec tions fr om the From Z ones selec tion list of the Iso-S urface dialo g box, you should ne ver selec t both the p orous fluid z one and the o verlapping solid z one a t the same time . Note tha t if no selec tions ar e made in this list , then all the c ell z ones ar e selec ted. •When mak ing selec tions fr om the Surfaces list of the Contours dialo g box, you should not selec t a sur face that is asso ciated with the p orous fluid z one and a sur face asso ciated with the o verlapping solid z one at the same time , if those sur faces ar e spa tially c oinciden t. •When p ostpr ocessing the ther mal c onduc tivit y pr operty in the p orous r egion, the v alue tha t is r eported for the fluid z one is the ther mal c onduc tivit y of the fluid ma terial sc aled b y the p orosity ( ) and f or the overlapping solid z one the v alue r eported is the ther mal c onduc tivit y of the solid z one sc aled b y the complemen t of the p orosity ( ); wher e is the p orosity, is the fluid phase ther mal c onduc tivit y (including the turbulen t contribution, ), and is the solid medium ther mal c onduc tivit y. 7.2.3.8.15. Specifying the R elativ e Visc osit y The r elative visc osity can b e used t o acc oun t for the eff ect of the p orous media on the diffusion term in the momen tum equa tion. By default , the r elative visc osity is set t o a c onstan t value of 1 (tha t is, the eff ective visc osity is equal t o the molecular visc osity).You c an cho ose t o mo del the r el- ative visc osity using one of the mo dels descr ibed in Relative Viscosity in P orous M edia (p.867), or you c an sp ecify a user-defined func tion using a DEFINE_PROPERTY macr o. 7.2.3.8.16. Specifying the R elativ e Permeabilit y The r elative permeabilit y of a phase denot es its abilit y to transmit the phase ma terial when its sa t- uration (v olume fr action) is less than 100%. Reser voir engineers of ten r esor t to empir ical mo dels or measur emen t cur ves to det ermine the r elative and , ther efore, the eff ective permeabilities . In F luen t, the C orey power la w mo del [18] (p.4006 ) is available t o acc oun t for the r elative permeabilit y for the t wo-phase flo w thr ough p orous media. The Corey correlations of the r elative permeabilit y can b e represen ted as f ollows: (7.42) wher e: is the r eference phase r elative permeabilit y is the nor maliz ed sa turation in the qth phase is the C orey exponen t for the qth phase In Fluen t the phase sa turation is the phase v olume fr action. Thus can b e expressed as: (7.43) wher e is the v olume fr action r esidual in the qth phase . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 886Cell Z one and B oundar y ConditionsFor the t wo-phase oil-w ater flo w example , the r elative permeabilities c an b e obtained fr om: (7.44) This r equir es the sp ecific ation of 6 par amet ers: the r eference phase r elative permeabilities f or the t wo phases and the r esidual v olume fr actions f or the t wo phases and the C orey exponen ts for the t wo phases and The C orey correlation is of ten used f or appr oxima tion of the r elative permeabilities , par ticular ly for water flo oding t ype sc enar ios.The r elative permeabilit y cur ves of the oil (or the non-w etting phase) is usually an S-shap ed cur ve and of the w ater (or the w etting phase) is a c oncave up ward cur ve. Alternatively, if relative permeabilit y da ta for one or t wo phases ar e available as tabular func tions of other solution v ariables , you c an use gener ic text files t o input such da ta to define phase r elative permeabilit y as descr ibed in Specifying Variables in a Tabular F ormat (p.894). To mo del the r elative permeabilit y in ANSY S Fluen t: 1.Set par amet ers f or the mix ture phase ( mix ture is selec ted f or Phase in the Cell Z one C onditions task page). a.In the Fluid dialo g box, in the Porous Z one tab , under Rela tive Permeabilit y, selec t Corey M odel. 887Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Cell Z one C onditionsFigur e 7.22: The F luid D ialo g Box: Rela tive Permeabilit y b.From the dr op-do wn lists , selec t Wetting P hase and Non Wetting P hase . Imp ortant Although Equa tion 7.42 (p.886) through Equa tion 7.44 (p.887) are valid f or an y given phase , care must b e exercised in defining the w etting and non-w etting phases . 2.Set conditions f or the w etting phase (the w etting phase is selec ted fr om the Phase drop-do wn list in the Cell Z one C onditions task page). In the Fluid dialo g box, in the Porous Z one tab , specify the f ol- lowing par amet ers in the Wetting P hase Rela tive Permeabilit y group b ox: Minimum Rela tive Permeabilit y sets a lo wer limit f or the r elative permeabilit y for the w etting phase . A lo w value incr eases impac t of the r esistanc e due t o relative permeabilit y eff ects on the flo w.This helps t o avoid sa turation oversho ots and undersho ots (tha t is, phase sa turation dr opping b elow residual v alues) in simula tions carried out f or a long p eriod of time .The default v alue is 1.e-8. The default should w ork for most cases , but ma y be lowered in c ase undersho ot pr oblems p ersist. •Non-tabular inputs: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 888Cell Z one and B oundar y ConditionsReferenc e Rela tive Permeabilit y in Equa tion 7.44 (p.887) Corey Exponen t in Equa tion 7.44 (p.887) Residual S aturation in Equa tion 7.44 (p.887) •Tabular input: a.Selec t tabular and click Edit.... Note Prior t o using the tabular option, you must r ead a t ext file c ontaining phase relative permeabilit y da ta as descr ibed in Capillar y Pressur e Data in a Tabular Format (p.893). b.In the Table Input dialo g box tha t op ens, selec t the table appr opriate for y our fluid z one fr om the Table List and the names of the c olumns fr om the Saturation ( VOF) and Rela tive Permeab- ility selec tion lists . Figur e 7.23: The Table Input D ialo g Box for Rela tive Permeabilit y See Capillar y Pressur e Data in a Tabular F ormat (p.893) for details ab out the t ext file f ormat. 3.Similar ly, set c onditions f or the non-w etting phase (the non-w etting phase is selec ted fr om the Phase drop-do wn list in the Cell Z one C onditions task page). In the Fluid dialo g box, in the Porous Z one tab, specify the f ollowing par amet ers in the Non Wetting P hase Rela tive Permeabilit y group: Minimum Rela tive Permeabilit y sets a lo wer limit f or the r elative permeabilit y for the non-w etting phase .This it em is similar t o Minimum Rela tive Permeabilit y for the w etting phase . •Non-tabular Inputs: 889Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Cell Z one C onditionsReferenc e Rela tive Permeabilit y in Equa tion 7.44 (p.887) Corey Exponen t in Equa tion 7.44 (p.887) Residual S aturation in Equa tion 7.44 (p.887) •Tabular Input: The inputs ar e similar t o the tabular sp ecific ation f or the w etting phase . On r are occasions , the sa turation ma y still fall b elow residual sa turation. You c an fix the aff ected phase t o its r esidual sa turation and allo w the other phase t o pass thr ough nor mally b y issuing the following t ext commands: solve/set/multiphase-numerics/porous-media/relative-permeability enable fix option below residual saturation? [no] yes Note The pr evious t ext command is not supp orted f or c ases tha t use the tabular sp ecific ation metho d for phase r elative permeabilit y. 7.2.3.8.17. Specifying the C apillar y Pressur e When using the E uler ian multiphase mo del, you c an optionally sp ecify a sub-mo del f or c apillar y pressur e. When t wo or mor e phases ar e pr esen t in p ores, one of the phase (usually w ater) has a pr eference for the p ore sur faces.This phase is r eferred t o as the w etting phase , while the other phase is c alled the non-w etting phase .The b oundar y between the phases pr esen t in a p orous medium is also curved, due t o in terfacial t ension b etween the fluid , and this giv es rise t o a diff erence in the pr essur e across the in terface: (7.45) wher e and are the non-w etting and w etting phase pr essur es, respectively.The diff erence, is the c apillar y pr essur e. It presen ts a signific ant driving f orce under the c onditions of lo w flo w pressur e and high v olume fr action. At the p ore sc ale, capillar y pr essur e dep ends pr imar ily on the p ore geometr ic char acteristics (siz es, distr ibutions , etc.), interfacial t ensions and w ettabilit y (contact angles). At the M acro sc ale the c apillar y pressur e is gener ally assumed t o be a func tion of the sa turation of the w etting fluid: (7.46) Its value is of ten obtained either b y measur emen ts or c orrelations . In Fluen t, the c apillar y pr essur e eff ect is mo deled as an additional sour ce term in the w etting phase using one of the sub-mo dels descr ibed b elow. 7.2.3.8.17.1. Brooks-C orey Model Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 890Cell Z one and B oundar y Conditions7.2.3.8.17.2. Van-G enuch ten M odel 7.2.3.8.17.3. Leverett J-F unction 7.2.3.8.17.4. Skjae veland M odel 7.2.3.8.17.5. Capillar y Pressur e Data in a Tabular F ormat 7.2.3.8.17.6. Capillar y Pressur e Usage 7.2.3.8.17.1. Brooks-C orey Mo del The B rooks-C orey mo del [18] (p.4006 ) proposed the f ollowing r elationship f or c apillar y pr essur e for primar y dr ainage , in which the p orous media initially sa turated with w ater is in vaded with oil phase: (7.47) wher e is the r esulting nor maliz ed (eff ective) sa turation: (7.48) wher e and are the minimum and maximum v olume fr action (sa turation) v alues , respectively. By default and wher e is the r esidual sa turation of phase The v alue of is limit ed t o values gr eater than 0.001 in or der t o avoid an infinit e value f or c apillar y pr essur e. In or der t o solv e Equa tion 7.47 (p.891), the en try pr essur e, , and the par amet er related t o the pore siz e ar e requir ed.The default v alues in F luen t are and which ar e appr o- priate for air-w ater flo w in sand [20] (p.4006 ). 7.2.3.8.17.2. Van-G enucht en Mo del Another w ell established par ametr ic mo del w as pr oposed b y van G enuch ten [37] (p.4007 ): (7.49) wher e is the en try pr essur e. is the p ore siz e distr ibution and .The default v alues inFluen t are and which ar e appr opriate for air-w ater flo w in sand [20] (p.4006 ). 7.2.3.8.17.3. Leverett J-F unc tion The J-func tion w as de velop ed b y Leverett in an a ttempt t o extend the p ore-sc ale c apillar y pr essur e formula tion b y Washbur n [20] (p.4006 ) to a M acro-sc ale c apillar y pr essur e mo del. Leverett pr oposed that the a veraged p ore radius c an b e expressed in t erms of p orosity and p ermeabilit y: (7.50) Further mor e, he ack nowledged tha t the c apillar y pr essur e should dep end on p orosity and p ermeab- ility. By analo gy to the Washbur n equa tion, he de velop ed a dimensionless J-func tion [64] (p.4008 ): (7.51) (7.52) wher e is the sur face tension, is the w etting or c ontact angle , and and are fitting par amet ers. Various empir ical J-func tions c an b e de velop ed t o estima te capillar y pr essur e. In the F luen t, the f ol- lowing f ormula tion is used: 891Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Cell Z one C onditions(7.53) This is the same f ormula tion as is used in the F luen t Fuel C ell M odule (see Liquid Water F ormation, Transp ort, and its E ffects (PEMFC Only) in the Fluent Theor y Guide ). 7.2.3.8.17.4. Skjae veland Mo del All of the ab ove-men tioned c apillar y pr essur e mo dels (B rooks-C orey,Van-G enuch ten, Leverett J- Function) ar e limit ed t o pr imar y dr ainage pr ocesses .Water sa turation decr eases in a pr imar y dr ainage process.To mo del a displac emen t process wher e flo oding is imp ortant, such as w ater-dr ive, mo dels that descr ibe imbibition ar e requir ed. However, most r eser voirs ar e mix ed w ettabilt y and f or these systems a mor e compr ehensiv e mo del tha t descr ibes b oth dr ainage and imbibition pr ocesses is r e- quir ed.The S kjae veland mo del f or c apillar y pr essur e enc ompasses these f eatures. The S kjae veland mo del [117] (p.4011 ) for c apillar y pr essur e treats the t wo fluids symmetr ically f or wettabilit y.The S kjae veland c apillar y pr essur e cur ve is defined b y Equa tion 7.54 (p.892). (7.54) Where is the c apillar y pr essur e of the phase , and are fitting par amet ers, and are constan ts, and and are the v olume fr actions of the t wo phases . and subscr ipts r efer to wetting and non-w etting phases , respectively. The p ositiv e par t of the c apillar y pr essur e cur ve is defined b y and . and define the nega tive portion of the c apillar y pr essur e cur ve.The eff ects of v arying , , , and on the capillar y pr essur e cur ve ar e sho wn in Figur e 7.24: Skjae veland C orrelation B ehavior [117] (p.893). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 892Cell Z one and B oundar y ConditionsFigur e 7.24: Skjae veland C orrelation B eha vior [117] (p.4011 ) Figur e 7.24: Skjae veland C orrelation B ehavior [117] (p.893) sho ws tha t ther e is a lot of fle xibilit y in the c apillar y pr essur e cur ve.You c an add fur ther fle xibilit y to the c apillar y pr essur e cur ve by estim- ating the r esidual oil sa turation. Note tha t by varying and you c an mo dify the cr oss-o ver p oint (while k eeping and unchanged). Default Value Paramet er 9.e5 9.e5 0.05 0.05 7.2.3.8.17.5. Capillar y Pressur e Data in a Tabular F ormat Often, field da ta for c apillar y pr essur e ar e available as tabular func tions of other solution v ariables . In, ANSY S Fluen t, you c an use a tabular metho d to sp ecify c apillar y pr essur e. Multiple files c an b e used t o sp ecify z one-sp ecific pr operties, for e xample , diff erent mo dels f or c apillar y pr essur e for dif- ferent zones . The t ext file f ormat and the table r eading pr ocedur e ar e descr ibed in Specifying Variables in a Tab- ular F ormat (p.894). Row 3 and all c onsecutiv e rows of the table must c ontain da ta p oints of the saturation and the c orresponding c apillar y pr essur e values as a func tion of the sa turation. See Capillar y Pressur e Usage (p.895) for mor e inf ormation on tabular input f or c apillar y pr essur e. 893Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Cell Z one C onditions7.2.3.8.17.5.1. Specifying Variables in a Tabular F ormat When the tabular input option is a vailable f or a solution v ariable , you c an sp ecify the v ariable as a tabular func tion of other solution quan tities using one or mor e gener ic text files .The tabular metho d uses a bisec tion algor ithm along with lo cal linear in terpolation t o find the v alue of the tabula ted quan tity. An example of the da ta file f or the c apillar y pr essur e variable is sho wn b elow. Default-Skjaevland-Model Sw Pc 0.2122 195399.0883 0.2245 156423.6016 0.2367 134012.8962 0.249 117936.4991 0.2612 105469.0929 0.2735 95079.83957 0.2857 86245.04955 0.298 78405.02466 The t ext file c an b e an y tab- (or spac e-) delimit ed file and must c ontain the f ollowing en tries: Row 1 – The name of the table .The name should not e xceed 128 char acters and c ontain no spac es. For e xample ,Default-Skjaevland-Model and Default_Skjaevland_Model are acc eptable names . Row 2 – C olumn names f or the table input da ta (Sw and Pc in the ab ove example). Row 3 and all c onsecutiv e rows – D ata p oints. Note tha t although ther e ar e no limits on the numb er of rows and c olumns , the files ar e in tended t o be relatively small (a f ew hundr ed da ta p oints max- imum), sinc e the y will b e stored as par t of the c ase file . Each r ow in the table must b e termina ted b y a newline or c arriage r etur n with no spac e or tab f ol- lowing the last en try in the r ow. You must pr ovide an adequa te numb er of da ta p oints in or der t o obtain meaning ful r esults f or in- terpolated v ariables .The v alues of the in terpolated quan tity app earing in the first and last r ows of the table ar e used as its lo wer and upp er b ounds , respectively. To read the table in to ANSY S Fluen t: 1.In the User-D efined ribbon tab , click Read Table (User-D efined group). User-D efined → User-D efined → Read Table 2.In the Table F ile M anager dialo g box tha t op ens, click Read .... 3.Use the Selec t File dialo g box to selec t the file c ontaining the c apillar y pr essur e da ta to be read. Onc e ANSY S Fluen t loads the file , the table name app ears in the Tables selec tion list in the Table File M anager dialo g box (see Figur e 7.25: The Table F ile M anager D ialog Box (p.895)).The table a t- tribut es, such as the table t ype and numb er of r ows and c olumns , are displa yed in the Info field . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 894Cell Z one and B oundar y ConditionsFigur e 7.25: The Table F ile M anager D ialo g Box You c an add or delet e tables a t an y time b y using the Read ... or Delet e... butt ons. Unlike lo cally st ored files , these tables , onc e read in, are wr itten out as par t of the F luen t case file . You do not ha ve to main tain lo cal copies of the tables . 7.2.3.8.17.6. Capillar y Pressur e Usage To mo del the c apillar y pr essur e: 1. In the Fluid dialo g box for the phase mix ture, in the Porous Z one tab , selec t Corey M odel (Model Options group b ox). 2. Selec t a mo del fr om the dr op-do wn list under Capillar y Pressur e.You c an cho ose fr om the f ollowing models: •brooks-c orey •van-genuch ten •leverett-j-func tion •skjae veland •tabular Note tha t prior t o using the tabular option, you must load a t ext file c ontaining c apillar y pressur e da ta as descr ibed in Capillar y Pressur e Data in a Tabular F ormat (p.893). 3. (tabular only) In the Table Input dialo g box tha t op ens when y ou selec t tabular , selec t the table ap- propriate for y our fluid z one fr om the Table List and the names of the c olumns fr om the Saturation (VOF) and Capillar y Pressur e selec tion lists . 895Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Cell Z one C onditionsFigur e 7.26: The Table Input D ialo g Box for C apillar y Pressur e For details ab out c apillar y pr essur e table files , see Capillar y Pressur e Data in a Tabular Format (p.893). Note You c an also define c apillar y pr essur e as a tabular func tion b y using the t ext com- mands a vailable under define/boundary-conditions/set/fluid . Onc e you enter mixture for domain id/name , you c an selec t the capillary-pressure TUI option, set the metho d to tabular and sp ecify its par amet ers. 4. Specify Maximum C apillar y Pressur e. The c apillar y pr essur e gr aph e xhibits asympt otic b ehavior a t the r esidual sa turation of w etting and non-w etting phases wher e the c apillar y pr essur e appr oaches plus and minus infinit y (see Figur e 6.82: The A ctivate Cell Z ones D ialog Box (p.818)). For this r eason, the c apillar y pr essur e must b e limit ed t o avoid numer ical pr oblems . 5. (Brooks-C orey mo del only) In the sec ondar y phase Fluid dialo g box, in the Porous Z one tab , specify the mo del-sp ecific par amet ers ( Brooks-C orey M odel Inputs group b ox): Entry pr essur e is in Equa tion 7.47 (p.891). Pore siz e exponen t is the par amet er in Equa tion 7.47 (p.891). 6. (Van-G enuch ten mo del only) In the sec ondar y phase Fluid dialo g box, in the Porous Z one tab , specify the mo del-sp ecific par amet ers ( Van-G enuch ten M odel Inputs group b ox): Entry pr essur e is in Equa tion 7.49 (p.891). Pore siz e exponen t is in Equa tion 7.49 (p.891). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 896Cell Z one and B oundar y Conditions7. (Skjae veland mo del only) In the Fluid dialo g boxes for the pr imar y and sec ondar y phases , in the Porous Zone tab , specify the mo del-sp ecific par amet ers ( Skjae veland M odel Inputs group b ox): Entry pr essur e is a c onstan t for the w etting phase and for the non-w etting phase in Equa tion 7.54 (p.892). Pore siz e exponen t is for the w etting phase and for the non-w etting phase in Equa tion 7.54 (p.892). 8. (Leverett J-F unction mo del only) S pecify the f ollowing mo del-sp ecific par amet ers: 1.In the Fluid dialo g boxes for the sec ondar y phase , in the Porous Z one tab , in the Leverett J- Func tion M odel Inputs group b ox, specify Contact Angle ( in Equa tion 7.51 (p.891)). 2.In the Phase In teraction dialo g boxes, in the Surface Tension tab , specify Surface Tension Coefficien t ( in Equa tion 7.51 (p.891)). Alternatively, you c an sp ecify a user-defined func tion tha t calcula tes the c apillar y pr essur e using a DEFINE_EXCHANGE_PROPERTY macr o. Note When mo deling the c apillar y pr essur e, you should ensur e tha t the w etting phases ar e chosen as the sec ondar y phases . Postpr ocessing The f ollowing additional field v ariable is a vailable f or sec ondar y phases: •Capillar y-Pressur e Note tha t, although this it em is a vailable f or b oth non-w etting and w etting phases , meaning ful values ar e reported only f or the w etting phase . 7.2.3.8.18. Defining S our ces If you w ant to include eff ects of the hea t gener ated b y the p orous medium in the ener gy equa tion, enable the Sour ce Terms option and set a nonz ero Energy sour ce.The solv er will c omput e the hea t gener ated b y the p orous r egion b y multiplying this v alue b y the t otal v olume of the c ells c ompr ising the p orous z one .You ma y also define sour ces of mass , momen tum, turbulenc e, species , or other scalar quan tities , as descr ibed in Defining M ass, Momen tum, Ener gy, and O ther S ources (p.908). 7.2.3.8.19. Defining F ixed Values If you w ant to fix the v alue of one or mor e variables in the fluid r egion of the z one , rather than computing them dur ing the c alcula tion, you c an do so b y enabling the Fixed Values option. See Fixing the Values of Variables (p.904) for details . 7.2.3.8.20. Suppr essing the Turbulent Visc osit y in the P orous R egion As discussed in Treatmen t of Turbulenc e in P orous M edia (p.869), turbulenc e will b e comput ed in the p orous r egion just as in the bulk fluid flo w. If you ar e using one of the turbulenc e mo dels (other 897Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Cell Z one C onditionsthan the Lar ge E ddy Simula tion mo del) and y ou w ant the turbulenc e gener ation t o be zero in the porous z one , turn on the Laminar Z one option in the Fluid dialo g box. Refer to Specifying a Lam- inar Z one (p.856) for mor e inf ormation ab out suppr essing turbulenc e gener ation. 7.2.3.8.21. Specifying the R otation A xis and D efining Z one Motion Inputs f or the r otation axis and z one motion ar e the same as f or a standar d fluid z one . See Inputs for F luid Z ones (p.854) for details . 7.2.3.9. Solution Str ategies for P orous Media In gener al, you c an use the standar d solution pr ocedur es and solution par amet er settings when y our ANSY S Fluen t mo del includes p orous media. You ma y find , however, tha t the r ate of c onvergenc e slows when y ou define a p orous r egion thr ough which the pr essur e dr op is r elatively lar ge in the flow dir ection (f or e xample , the p ermeabilit y, , is lo w or the iner tial fac tor, , is lar ge). This slo w convergenc e can o ccur b ecause the p orous media pr essur e dr op app ears as a momen tum sour ce term—yielding a loss of diagonal dominanc e—in the ma trix of equa tions solv ed.The b est r emed y for p oor c onvergenc e of a pr oblem in volving a p orous medium is t o supply a go od initial guess f or the pr essur e dr op acr oss the medium. Similar ly,Standar d Initializa tion is the r ecommended initializa tion metho d for p orous media simu- lations .The default Hybr id Initializa tion metho d do es not acc oun t for the p orous media pr operties, and dep ending on b oundar y conditions , ma y pr oduce an unr ealistic initial v elocity field . For p orous media simula tions , the Hybr id Initializa tion metho d should only b e used with the Maintain C onstan t Velocity M agnitude option. Another p ossible w ay to deal with p oor c onvergenc e is t o temp orarily disable the p orous media model (b y tur ning off the Porous Z one option in the Fluid D ialog Box (p.3457 )) and obtain an initial flow field without the eff ect of the p orous r egion. With the p orous media mo del tur ned off , ANSY S Fluen t will tr eat the p orous z one as a fluid z one and c alcula te the flo w field acc ordingly . Onc e an initial solution is obtained , or the c alcula tion is pr oceeding st eadily t o convergenc e, you c an enable the p orous media mo del and c ontinue the c alcula tion with the p orous r egion included . (This metho d is not r ecommended f or p orous media with high r esistanc e.) Simula tions in volving highly anisotr opic p orous media ma y, at times , pose c onvergenc e troubles .You can addr ess these issues b y limiting the anisotr opy of the p orous media c oefficien ts ( and ) to two or thr ee or ders of magnitude . Even if the medium ’s resistanc e in one dir ection is infinit e, you do not need t o set the r esistanc e in tha t dir ection t o be gr eater than 1000 times the r esistanc e in the primar y flo w dir ection. 7.2.3.10. Postpr ocessing for P orous Media The impac t of a p orous r egion on the flo w field c an b e det ermined b y examining either v elocity comp onen ts or pr essur e values . Graphic al plots (including X Y plots and c ontour or v ector plots) or alphanumer ic reports of the f ollowing v ariables/func tions ma y be of in terest: •X,Y,Z Velocity (in the Velocity... categor y) •Static P ressur e (in the Pressur e... categor y) These v ariables ar e contained in the sp ecified c ategor ies of the v ariable selec tion dr op-do wn list tha t app ears in p ostpr ocessing dialo g boxes. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 898Cell Z one and B oundar y ConditionsNote tha t ther mal r eporting in the p orous r egion is defined as f ollows: (7.55) wher e = p orosity of the medium = fluid phase ther mal c onduc tivit y (including the turbulen t contribution, ) = solid medium ther mal c onduc tivit y Imp ortant For p orous media in volving sur face reactions , you c an displa y/report the sur face reaction rates using the Arrhenius R ate of Reac tion-n in the Reac tions ... categor y of the v ariable selec tion dr op-do wn list. Imp ortant Special c are must b e tak en when p ostpr ocessing a p orous media simula tion tha t utiliz es the non-equilibr ium ther mal mo del. See Non-E quilibr ium Thermal M odel (p.884) for details . 7.2.4. 3D F an Z ones 3D fan z ones ar e fluid c ell z ones tha t simula te the eff ect of an axial fan b y applying a distr ibut ed mo- men tum sour ce in a t oroid-shap ed fluid v olume (tha t is, a blade-sw ept v olume). This is in c ontrast t o fan b oundar y conditions (f or e xample , a b oundar y zone of t ype fan or intake-fan ), which ar e based on a lump ed par amet er mo del in which the fan is c onsider ed t o be infinit ely thin and a disc ontinuous pressur e rise is sp ecified as a func tion of v elocity. 3D fan z ones ha ve the f ollowing ad vantages: •3D fan z ones c an c alcula te swir l and r adial v elocities , as opp osed t o fan b oundar y conditions , which ar e mainly used t o simula te the axial flo w and r equir e you t o input swir l and r adial c oefficien ts. •The r esults f or 3D fan z ones c an b e compar able t o mo ving r eference frame (MRF) simula tions , and do not requir e mo deling 3D r otating fan blade geometr ies. •3D fan z ones c an simula te a fan e ven if the a vailable fan cur ve da ta w as measur ed a t diff erent op erating conditions than tha t of the simula tion. Note Fluid z ones designa ted as 3D fan z ones c annot ha ve non-c onformal in terfaces. 7.2.4.1. Momentum E quations for 3D F an Z ones The f ollowing equa tions ar e used in the 3D fan z one f or the momen tum sour ces in the axial, tangen tial, and r adial dir ections , which mimic the eff ect of the fan on the fluid .The tangen tial momen tum sour ce is based on a turb omachiner y relation, wher eas the r adial momen tum sour ce is based on a c entrifugal force balanc e. (7.56) 899Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Cell Z one C onditions(7.57) (7.58) wher e = pr essur e rise acr oss the fan f or a giv en axial flo w rate = thick ness of the t oroid r egion sw ept b y the blades in the axial dir ection = fan p ower = lo cal radial distanc e from the fan axis = fan op erating angular v elocity = radius of the fan hub = radius of a p oint on the fan blade based on the inflec tion p oint ratio = radius of the fan blade tip = fluid densit y = lo cal tangen tial v elocity In or der t o calcula te the tangen tial sour ce, three other e xpressions ar e nec essar y: (7.59) (7.60) (7.61) wher e = v elocity vector a t the fan e xit plane = ar ea v ector a t the fan e xit plane = the inflec tion p oint ratio, tha t is, the fr action of the fan blade length (star ting at the hub) o ver which the tangen tial v elocity of the fan dischar ge is incr easing with increasing r adius and p eaks , before tap ering off (see Figur e 7.28: The Inflec tion P oint Ratio of a P itched B lade Turbine (p.903)) The pr essur e rise acr oss the 3D fan z one is sp ecified as a func tion of the v olumetr ic flo w rate thr ough the fan. The r elationship ma y be a c onstan t or a fan cur ve, tha t is, a p olynomial or piec ewise-linear func tion. In the c ase of a p olynomial, the r elationship is of the f orm (7.62) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 900Cell Z one and B oundar y Conditionswher e are the pr essur e head p olynomial c oefficien ts (c alcula ted b y Fluen t), and is the flo w rate normal t o the fan. Imp ortant The flo w rate can b e either p ositiv e or nega tive.You must b e careful t o mo del the fan so tha t a pr essur e rise o ccurs f or forward flo w thr ough the fan. The fan cur ve da ta is t ypic ally c ollec ted a t a pr escr ibed set of t est c onditions . However, the op erating conditions of y our CFD simula tion ma y be inc onsist ent with this da ta (f or e xample , the r otational speed or fluid t emp erature ma y be diff erent).To acc oun t for this , the 3D fan mo del c an adjust the fan cur ve da ta acc ording t o the f ollowing sc aling r elationships: (7.63) (7.64) (7.65) wher e and are the t est t emp erature and the v olume-a veraged t emp erature of the fan c ell zone (which is c alcula ted in ternally), respectively. 7.2.4.2. User Inputs for 3D F an Z ones A 3D fan z one is mo deled as a sp ecial t ype of fluid z one .The c ell z one should ha ve a t oroid shap e that is siz ed t o ma tch the blade-sw ept v olume of the fan y ou ar e simula ting (tha t is, has an inner and outer radius tha t ma tches the r adius of the fan ’s hub and blade tips , respectively, as w ell as a length that ma tches the thick ness of the t oroid r egion sw ept b y the blades in the axial dir ection). Further mor e, the fluid c ell z one should b e “interior”, tha t is, have at least t wo boundar y zones of t ype interior tha t border another fluid c ell z one and ac t as the fan inlet and outlet (the other b oundar ies c an b e of type interior as w ell). To designa te a c ell z one as a 3D fan z one , enable the 3D F an Z one option in the Fluid dialo g box and then define the geometr y and pr operties of the fan in the 3D F an Z one tab . 901Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Cell Z one C onditionsFigur e 7.27: The F luid D ialo g Box for a 3D F an Z one 7.2.4.2.1. Defining the G eometr y of a 3D F an Z one After enabling the 3D F an Z one option in the Fluid dialo g box, you c an b egin setting it up b y de- fining the settings in the Geometr y group b ox in the 3D F an Z one tab of the fluid c ell z one: 1. Selec t a b oundar y zone fr om the Inlet F an Z one drop-do wn list , which will ac t as the inlet z one f or the 3D fan z one and the sur face on which the fan will b e located.This b oundar y must meet c ertain requir emen ts: it must b e of t ype interior; it must b e planar ; and it must ac t as a b oundar y between the 3D fan z one and another fluid c ell z one . Note tha t the dir ection the fan blo ws will b e into the 3D fan z one , perpendicular t o this b oundar y zone . 2. Define the o verall dimensions of the fan b y en tering v alues f or the Hub R adius and the Tip R adius , as w ell as the Thick ness of the t oroid r egion sw ept b y the blades in the axial dir ection. Note tha t the values must fit within the c onfines of the 3D fan z one , and tha t the Thick ness will b e applied fr om the Inlet F an Z one into the 3D fan z one . 3. Specify the Inflec tion P oint ratio.The inflec tion p oint ratio r epresen ts the fr action of the fan blade length (star ting a t the hub) o ver which the tangen tial v elocity of the fan dischar ge is incr easing with increasing r adius and p eaks , before tap ering off . See Figur e 7.28: The Inflec tion P oint Ratio of a P itched Blade Turbine (p.903) for an illustr ation. You c an der ive this r atio empir ically fr om e xperimen tal da ta; other wise , you c an first use ANSY S Fluen t to mo del the ac tual fan geometr y (for e xample , using a moving r eference frame simula tion) and then use those r esults t o det ermine the input par amet ers f or simpler simula tions using the 3D F an Z one option. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 902Cell Z one and B oundar y ConditionsFigur e 7.28: The Inflec tion P oint Ratio of a P itched Blade Turbine 4. Enter the c oordina tes for the Fan Or igin .This must define a p oint tha t is on the plane of the Inlet F an Zone and lo cated such tha t the diamet ers of the fan fall within b oundar ies of the Inlet F an Z one . 7.2.4.2.2. Defining the P roperties of a 3D F an Z one To complet e the setup of a 3D fan z one , you must define the settings in the Properties group b ox in the 3D F an Z one tab of the fluid c ell z one: 1. Define the Rota tional D irection of the fan. The r otation is deemed positiv e if it f ollows the r ight-hand rule with r espect to the fan dir ection v ector (tha t is, a vector fr om the Fan Or igin tha t points in to the 3D fan z one p erpendicular t o the Inlet F an Z one ). 2. Specify the Operating A ngular Velocity of the fan. This must b e a p ositiv e nonz ero numb er. 3. You c an enable the Limit F low R ate Through F an option, and ther eby sp ecify the Maximum and Minimum flow rates tha t are allo wed. 4. You c an enable the Tangen tial S our ce Term,Radial S our ce Term, and/or Axial S our ce Term options , in or der t o enable momen tum sour ces in the sp ecified dir ections . Note tha t the tangen tial and r adial sour ces ar e defined acc ording t o imp eller theor y, and so no fur ther inputs ar e nec essar y, wher eas the axial sour ce term requir es additional input (as descr ibed in the st ep tha t follows). 5. If you ha ve enabled the Axial S our ce Term option, you must define this sour ce in the Axial S our ce Term S ettings group b ox. For the Metho d, you c an selec t one of the f ollowing choic es: •constan t pr essur e 903Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Cell Z one C onditionsWith this metho d, you must then sp ecify a c onstan t Pressur e Jump tha t is applied t o all of the c ells in the 3D fan z one . •fan cur ve This metho d allo ws you t o sp ecify the pr essur e jump thr ough a fan cur ve (pr essur e rise v s. volumetr ic flo w rate). Using the Read F an C urve... butt on, you c an r ead in a tab-delimit ed ASCII file tha t defines the r elationship b etween pr essur e and flo w rate for the 3D fan c ell zone (see 3D F an C urve File F ormat (p.3987 ) for details). You must then sp ecify the Curve Fitting Metho d Fluen t should use on the da ta p oints in y our file , selec ting either polynomial or piec ewise-linear (for the f ormer , you must then define the Order of P olynomial ). Finally , you must pr ovide an estima te of the Initial F low R ate through y our fan z one , as w ell as the Test A ngular Velocity and Test Temp erature of the e xperimen t tha t produced the da ta points. Note tha t a single file c an define multiple c ell z ones , but the file must b e read in each of the applic able Fluid dialo g boxes. 7.2.4.3. 3D F an Z one Limitations Note the f ollowing limita tions when setting up a 3D fan z one: •3D fan z ones ar e not supp orted with the pr emix ed c ombustion mo del. •3D fan z ones ar e not supp orted with the E uler ian multiphase mo del. •The Energy Equa tion must b e enabled in the Ener gy Dialog Box (p.3252 ) for 3D fan z ones when fan cur ve is selec ted f or the axial sour ce term metho d. 7.2.5. Fixing the Values of Variables The option t o fix v alues of v ariables in ANSY S Fluen t allo ws you t o set the v alue of one or mor e variables in a fluid or solid z one , essen tially setting a b oundar y condition f or the v ariables within the c ells of the z one .When a v ariable is fix ed in a giv en c ell, the tr ansp ort equa tion f or tha t variable is not solv ed in the c ell (and the c ell is not included when the r esidual sum is c omput ed f or tha t variable). The fix ed value is used f or the c alcula tion of fac e flux es b etween the c ell and its neighb ors.The r esult is a smo oth transition b etween the fix ed v alue of a v ariable and the v alues a t the neighb oring c ells. Imp ortant You c an fix v alues f or temp erature, species mass fr actions , and/or v elocity comp onen ts only if you ar e using the pr essur e-based solv er. (Refer to Pressur e-Based S olver in the Theor y Guide for inf ormation ab out the pr essur e-based solv er.) 7.2.5.1. Overview of F ixing the Value of a Variable The abilit y to fix the v alue of a v ariable has a wide r ange of applic ations .The v elocity fixing metho d is of ten used t o mo del the flo w in stir red tanks .This appr oach pr ovides an alt ernative to the use of a mo ving r eference frame (solution in the r eference frame of the blade) and c an b e used t o mo del baffled tanks . In b oth 2D and 3D geometr ies, a fluid c ell z one ma y be used in the imp eller r egions , and v elocity comp onen ts can b e fix ed based on measur ed da ta. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 904Cell Z one and B oundar y ConditionsAlthough the ac tual imp eller geometr y can b e mo deled and the flo w pa ttern calcula ted using the sliding mesh mo del, experimen tal da ta for the v elocity pr ofile in the outflo w region ar e available f or man y imp eller t ypes. If you do not need t o know the details of the flo w ar ound the blades f or y our problem, you c an mo del the imp eller b y fixing the e xperimen tally-obtained liquid v elocities in its outflo w zone .The v elocities in the r est of the v essel c an then b e calcula ted using this fix ed v elocity profile as a b oundar y condition. Figur e 7.29: Fixing Values f or the F low in a S tirred Tank (p.905) sho ws an e xample of ho w this metho d is used t o mo del the flo w pa ttern cr eated b y a disk-turbine in an axisymmetr ic stir red v essel. Figur e 7.29: Fixing Values f or the F low in a S tirred Tank 7.2.5.1.1. Variables That C an B e Fixed The v ariables tha t can b e fix ed include v elocity comp onen ts (pr essur e-based solv er only), turbulenc e quan tities , temp erature (pr essur e-based solv er only), enthalp y, species mass fr actions (pr essur e-based solv er only), and user-defined sc alars . For turbulenc e quan tities , diff erent values c an b e set dep ending on y our choic e of turbulenc e mo del. You c an fix the v alue of the t emp erature in a fluid or solid z one if you ar e solving the ener gy equa tion. If you ar e using the non-pr emix ed c ombustion mo del, you can fix the en thalp y in a fluid z one . If you ha ve mor e than one sp ecies in y our mo del, you c an sp ecify fixed v alues f or the sp ecies mass fr actions f or each individual sp ecies e xcept the last one y ou defined . See the Fluen t Customiza tion M anual for details ab out defining user-defined sc alars . 905Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Cell Z one C onditionsIf you ar e using the E uler ian multiphase mo del, you c an fix the v alues of v elocity comp onen ts and (dep ending on which multiphase turbulenc e mo del y ou ar e using) turbulenc e quan tities on a p er- phase basis . See Euler ian M odel (p.2135 ) for details ab out setting b oundar y conditions f or E uler ian multiphase c alcula tions . 7.2.5.2. Procedur e for F ixing Values of Variables in a Z one To fix the v alues of one or mor e variables in a c ell z one , follow these st eps (r ememb ering t o use only SI units): 1.In the Fluid D ialog Box (p.3457 ) or Solid D ialog Box (p.3467 ), enable the Fixed Values option. 2.Fix the v alues f or the appr opriate variables in the Fixed Values tab , noting the c ommen ts below. •To sp ecify a c onstan t value f or a v ariable , cho ose constan t in the dr op-do wn list ne xt to the r elevant field and then en ter the c onstan t value in the field . •To sp ecify a non-c onstan t value f or a v ariable , you c an use a pr ofile (see Profiles (p.1051 )) or a user- defined func tion f or a pr ofile (see the Fluen t Customiza tion M anual ). Selec t the appr opriate pr ofile or UDF in the dr op-do wn list ne xt to the r elevant field . If you sp ecify a r adial-t ype pr ofile (see Profile S pecific ation Types (p.1051 )) for temp erature, en- thalp y, species mass/mole fr actions , or turbulenc e quan tities f or the - , Spalar t-Allmar as, or - mo del, the lo cal coordina te sy stem up on which the r adial pr ofile is based is defined b y the Rota tion-A xis Or igin and Rota tion-A xis D irection for the fluid z one . See Specifying the Rotation A xis (p.856) for inf ormation ab out setting these par amet ers. (Note tha t it is acc eptable to sp ecify the r otation axis and dir ection f or a non-r otating z one .This will not c ause the z one to rotate; it will not r otate unless it has b een e xplicitly defined as a mo ving z one .) •If you do not w ant to fix the v alue f or a v ariable , cho ose (or k eep) none in the dr op-do wn list ne xt to the r elevant field .This is the default f or all v ariables . 7.2.5.2.1. Fixing Velocity Comp onents To fix the v elocity comp onen ts, you c an sp ecify X,Y, and (in 3D) Z Velocity values , or, for axisym- metr ic cases ,Axial ,Radial , and (f or axisymmetr ic swir l) Swirl Velocity values .The units f or a fix ed velocity are m/s . For 3D c ases , you c an cho ose t o sp ecify c ylindr ical velocity comp onen ts inst ead of C artesian c om- ponen ts.Turn on the Local C oordina te System F or F ixed Velocities option, and then sp ecify the Axial ,Radial , and/or Tangen tial Velocity values .The lo cal coordina te sy stem is defined b y the Rota tion-A xis Or igin and Rota tion-A xis D irection for the fluid z one . See Specifying the R otation Axis (p.856) for inf ormation ab out setting these par amet ers. (Note tha t it is acc eptable t o sp ecify the rotation axis and dir ection f or a non-r otating z one .This will not c ause the z one t o rotate; it will not rotate unless it has b een e xplicitly defined as a mo ving z one .) Imp ortant Note the f ollowing: •You c an fix v alues f or v elocity comp onen ts only if y ou ar e using the pr essur e-based solv er. (Refer to Pressur e-Based S olver in the Theor y Guide for inf ormation ab out the pr essur e-based solv er.) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 906Cell Z one and B oundar y Conditions•If all c omp onen ts of v elocity are set t o fix ed v alues , the solv er will also set the gauge pr essur e to zero on all c ells in the c ell z one . 7.2.5.2.2. Fixing Temp eratur e and E nthalp y If you ar e solving the ener gy equa tion, you c an fix the t emp erature in a z one b y sp ecifying the v alue of the Temp erature.The units f or a fix ed t emp erature ar e K. If you ar e using the non-pr emix ed c ombustion mo del, you c an fix the en thalp y in a z one b y sp ecifying the v alue of the Enthalp y.The units f or a fix ed en thalp y are J/k g. If you sp ecify a r adial-t ype pr ofile (see Profile S pecific ation Types (p.1051 )) for temp erature or en thalp y, the lo cal coordina te sy stem up on which the r adial pr ofile is based is defined b y the Rota tion-A xis Origin and Rota tion-A xis D irection for the fluid z one . See ab ove for details . Imp ortant You c an fix the v alue of t emp erature only if y ou ar e using the pr essur e-based solv er. 7.2.5.2.3. Fixing Sp ecies M ass F ractions If you ar e using the sp ecies tr ansp ort mo del, you c an fix the v alues of the sp ecies mass fr actions f or individual sp ecies . ANSY S Fluen t allo ws you t o fix the sp ecies mass fr action f or each sp ecies (f or e x- ample ,h2,o2) except the last one y ou defined . If you sp ecify a r adial-t ype pr ofile (see Profile S pecific ation Types (p.1051 )) for a sp ecies mass fr action, the lo cal coordina te sy stem up on which the r adial pr ofile is based is defined b y the Rota tion-A xis Origin and Rota tion-A xis D irection for the fluid z one . See ab ove for details . Imp ortant You c an fix v alues f or sp ecies mass fr actions only if y ou ar e using the pr essur e-based solv er. 7.2.5.2.4. Fixing Turbulenc e Q uantities To fix the v alues of and in the - equa tions , specify the Turbulenc e Kinetic E nergy and Tur- bulenc e D issipa tion R ate values .The units f or are / and those f or are / . To fix the v alue of the mo dified turbulen t visc osity ( ) for the S palar t-Allmar as mo del, specify the Modified Turbulen t Visc osit y value .The units f or the mo dified turbulen t visc osity are /s. To fix the v alues of and in the - equa tions , specify the Turbulenc e Kinetic E nergy and Specific D issipa tion R ate values .The units f or are / and those f or are 1/s . To fix the v alue of , , or the R eynolds str esses in the RSM tr ansp ort equa tions , specify the Turbu- lenc e Kinetic E nergy,Turbulenc e D issipa tion R ate,Specific D issipa tion R ate,UU Re ynolds S tress, VV Re ynolds S tress,WW Re ynolds S tress,UV Re ynolds S tress,VW Re ynolds S tress, and/or UW Reynolds S tress.The units f or and the R eynolds str esses ar e / , and those f or are / . 907Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Cell Z one C onditionsIf you sp ecify a r adial-t ype pr ofile (see Profile S pecific ation Types (p.1051 )) for , , , or , the lo cal coordina te sy stem up on which the r adial pr ofile is based is defined b y the Rota tion-A xis Or igin and Rota tion-A xis D irection for the fluid z one . See ab ove for details . Note tha t you c annot sp ecify radial-t ype pr ofiles f or the R eynolds str esses . 7.2.5.2.5. Fixing User -Defined Sc alars To fix the v alue of a user-defined sc alar, specify the User-defined sc alar-n value . (There will b e one for each user-defined sc alar y ou ha ve defined .) The units f or a user-defined sc alar will b e the appr o- priate SI units f or the sc alar quan tity. See the Fluen t Customiza tion M anual for inf ormation on user- defined sc alars . 7.2.6. Locking the Temp erature for S olid and S hell Z ones You c an lo ck (or “freeze”) the t emp erature values f or all the c ells in solid z ones (including c ells t o which you ha ve applied an ener gy sour ce using a UDF) and in w alls tha t ha ve shell c onduc tion enabled , so that the v alues do not change dur ing fur ther solv er it erations .When the t emp erature is lo cked f or a given c ell, the tr ansp ort equa tion will still b e solv ed in the c ell, and the c ell will b e included when the residual sum is c omput ed. You c an lo ck / unlo ck the t emp erature for solid and shell z ones b y using the f ollowing t ext command: solve → set → lock-solid-temperature? Note the f ollowing ab out the option f or lo cking the t emp erature of solid and shell z ones: •It is only a vailable when ener gy is enabled and the pr essur e-based solv er is selec ted. •When this option is used , the BCGST AB option fr om the Stabiliza tion M etho d drop-do wn list of the Ad- vanc ed S olution C ontrols dialo g box is not supp orted. •Alternative means of monit oring the c onvergenc e of ener gy ma y be used . 7.2.7. Defining M ass, Momen tum, Energy, and O ther S our ces You c an define v olumetr ic sour ces of mass (f or single or multiple sp ecies), momen tum, ener gy, turbu- lenc e, and other sc alar quan tities in a fluid z one , or a sour ce of ener gy for a solid z one .This f eature is useful when y ou w ant to input a k nown v alue f or these sour ces. (For mor e complic ated sour ces with func tional dep endenc y, you c an cr eate a user-defined func tion as descr ibed in the separ ate Fluen t Customiza tion M anual .) To add sour ce terms t o a c ell or gr oup of c ells, you must plac e the c ell(s) in a separ ate zone .The sour ces ar e then applied t o tha t cell z one .Typic al uses f or this f eature ar e list ed below: •A flo w sour ce tha t cannot b e represen ted b y an inlet , for e xample , due t o an issue of sc ale. If you need t o model an inlet tha t is smaller than a c ell, you c an plac e the c ell wher e the tin y “inlet ” is lo cated in its o wn fluid z one and then define the mass , momen tum, and ener gy sour ces in tha t cell z one . For the e xample shown in Figur e 7.30: Defining a S ource for a Tiny Inlet (p.909), you should set a mass sour ce of and a momen tum sour ce of , wher e is the c ell v olume . •Heat release due t o a sour ce (for e xample , fire) tha t is not e xplicitly defined in y our mo del. For this c ase, you c an plac e the c ell(s) in to which the hea t is or iginally r eleased in its o wn fluid z one and then define the ener gy sour ce in tha t cell z one . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 908Cell Z one and B oundar y Conditions•An ener gy sour ce in a solid z one , for conjuga te hea t transf er applic ations . For this c ase, you c an plac e the cell(s) in to which the hea t is or iginally r eleased in its o wn solid z one and then define the ener gy sour ce in that cell z one . •A sp ecies sour ce due t o a r eaction tha t is not e xplicitly included in the mo del. In the ab ove example of simula ting a fir e, you migh t need t o define a sour ce for a sp ecies r epresen ting smok e gener ation. Imp ortant Note tha t if y ou define a mass sour ce for a c ell z one , you should also define a momen tum sour ce and , if appr opriate for y our mo del, ener gy and turbulenc e sour ces. If you define only a mass sour ce, tha t mass en ters the domain with no momen tum or ther mal hea t.The mass will ther efore ha ve to be acc elerated and hea ted b y the flo w and , consequen tly, ther e ma y be a dr op in v elocity or t emp erature.This dr op ma y or ma y not b e perceptible , dep ending on the siz e of the sour ce. (Note tha t defining only a momen tum, ener gy, or turbulenc e sour ce is acc eptable .) Figur e 7.30: Defining a S our ce for a Tiny Inlet 7.2.7.1. Sign C onventions and Units All positiv e sour ce terms indic ate sour ces, and all nega tive sour ce terms indic ate sinks . All sour ces must b e sp ecified in SI units . 7.2.7.2. Procedur e for D efining S our ces To define one or mor e sour ce terms f or a z one , follow these st eps (r ememb ering t o use only SI units): 1.In the Fluid D ialog Box (p.3457 ) or Solid D ialog Box (p.3467 ), turn on the Sour ce Terms option. 2.Set the appr opriate sour ce terms under the Sour ce Terms tab , noting the c ommen ts below. 909Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Cell Z one C onditions•To sp ecify a sour ce, click the Edit... butt on ne xt to the mass , momen tum, ener gy, or other sour ce.The sour ces dialo g box will op en wher e you will define the numb er of sour ces. For each sour ce, cho ose none ,constan t, or New Input P aramet er... in the dr op-do wn list. •If you do not w ant to sp ecify a sour ce term for a v ariable , cho ose (or k eep) none in the dr op-do wn list next to the r elevant field .This is the default f or all v ariables . •To sp ecify a c onstan t sour ce, cho ose constan t in the dr op-do wn list and then en ter the c onstan t value in the field . •To sp ecify a new sour ce par amet er, cho ose New Input P aramet er... in the dr op-do wn list and en ter the Name or the par amet er and the Current Value as a c onstan t. •Rememb er tha t you should not define just a mass sour ce without defining the other sour ces, as de- scribed in Defining M ass, Momen tum, Ener gy, and O ther S ources (p.908). above. •Since the sour ces y ou sp ecify ar e defined p er unit v olume , to det ermine the appr opriate value of y our sour ce term you will of ten need t o first det ermine the v olume of the c ell(s) in the z one f or which y ou are defining the sour ce.To do this , you c an use the Volume In tegrals D ialog Box (p.3730 ). 7.2.7.2.1. Mass S our ces If you ha ve only one sp ecies in y our pr oblem, you c an simply define a Mass sour ce for tha t sp ecies . The units f or the mass sour ce ar e . In the c ontinuit y equa tion ( Equa tion 1.1 in the Theor y Guide ), the defined mass sour ce will app ear in the term. If you ha ve mor e than one sp ecies , you c an sp ecify mass sour ces for each individual sp ecies .There will b e a t otal Mass sour ce term as w ell as a sour ce term list ed e xplicitly f or each sp ecies (f or e xample , h2,o2) except the last one y ou defined . If the t otal of all sp ecies mass sour ces (including the last one) is 0, then y ou should sp ecify a v alue of 0 f or the Mass sour ce, and also sp ecify the v alues of the nonz ero individual sp ecies mass sour ces. Since you c annot sp ecify the mass sour ce for the last species e xplicitly , ANSY S Fluen t will c omput e it b y subtr acting the sum of all other sp ecies mass sour ces fr om the sp ecified t otal Mass sour ce. For e xample , if the mass sour ce for h ydrogen in a h ydrogen-air mix ture is 0.01, the mass sour ce for oxygen is 0.02, and the mass sour ce for nitr ogen (the last sp ecies) is 0.015, you will sp ecify a v alue of 0.01 in the h2 field , a value of 0.02 in the o2 field , and a v alue of 0.045 in the Mass field .This concept also applies within each c ell if y ou use user-defined func tions f or sp ecies mass sour ces. The units f or the sp ecies mass sour ces ar e . In the c onser vation equa tion f or a chemic al species ( Equa tion 7.1 in the Theor y Guide ), the defined mass sour ce will app ear in the term. 7.2.7.2.2. Momentum S our ces To define a sour ce of momen tum, specify the X M omen tum ,Y M omen tum , and/or Z M omen tum term.The units f or the momen tum sour ce ar e N/ . In the momen tum equa tion ( Equa tion 1.3 in the Theor y Guide ), the defined momen tum sour ce will app ear in the term. 7.2.7.2.3. Ener gy Sour ces To define a sour ce of ener gy, specify an Energy term.The units f or the ener gy sour ce ar e W/ . In the ener gy equa tion ( Equa tion 5.1 in the Theor y Guide ), the defined ener gy sour ce will app ear in the term. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 910Cell Z one and B oundar y Conditions7.2.7.2.4. Turbulenc e Sour ces 7.2.7.2.4.1. Turbulenc e Sour ces for the k- ε Mo del To define a sour ce of or in the - equa tions , specify the Turbulen t Kinetic E nergy or Turbulen t Dissipa tion R ate term.The units f or the sour ce ar e kg/m- and those f or are kg/m- . The defined sour ce will app ear in the term on the r ight-hand side of the turbulen t kinetic ener gy equa tion (f or e xample ,Equa tion 4.39 in the Theor y Guide ). The defined sour ce will app ear in the term on the r ight-hand side of the turbulen t dissipa tion rate equa tion (f or e xample ,Equa tion 4.40 in the Theor y Guide ). 7.2.7.2.4.2. Turbulenc e Sour ces for the Spalar t-Allmar as Mo del To define a sour ce of mo dified turbulen t visc osity, specify the Modified Turbulen t Visc osit y term. The units f or the mo dified turbulen t visc osity sour ce ar e kg/m- . In the tr ansp ort equa tion f or the Spalar t-Allmar as mo del ( Equa tion 4.15 in the Theor y Guide ), the defined mo dified turbulen t visc osity sour ce will app ear in the term. 7.2.7.2.4.3. Turbulenc e Sour ces for the k- ω Mo del To define a sour ce of or in the - equa tions , specify the Turbulen t Kinetic E nergy or Specific Dissipa tion R ate term.The units f or the sour ce ar e kg/m- and those f or are kg/ - . The defined sour ce will app ear in the term on the r ight-hand side of the turbulen t kinetic ener gy equa tion ( Equa tion 4.70 in the Theor y Guide ). The defined sour ce will app ear in the term on the r ight-hand side of the sp ecific turbulen t dissipa tion r ate equa tion ( Equa tion 4.71 in the Theor y Guide ). 7.2.7.2.4.4. Turbulenc e Sour ces for the R eynolds Str ess Mo del To define a sour ce of , , or the R eynolds str esses in the RSM tr ansp ort equa tions , specify the Turbulenc e Kinetic E nergy,Turbulenc e D issipa tion R ate,Specific D issipa tion R ate,UU Re ynolds Stress,VV Re ynolds S tress,WW Re ynolds S tress,UV Re ynolds S tress,VW Re ynolds S tress, and/or UW Re ynolds S tress terms.The units f or the sour ce and the sour ces of R eynolds str ess ar e kg/m- , and those f or are kg/m- . The defined R eynolds str ess sour ces will app ear in the term on the r ight-hand side of the Reynolds str ess tr ansp ort equa tion ( Equa tion 4.199 in the Theor y Guide ). The defined sour ce will app ear in the term on the r ight-hand side of Equa tion 4.227 in the Theor y Guide . The defined will app ear in the term on the r ight-hand side of Equa tion 4.230 in the Theor y Guide . 7.2.7.2.5. Mean M ixture Fraction and Varianc e Sour ces To define a sour ce of the mean mix ture fraction or its v arianc e for the non-pr emix ed c ombustion model, specify the Mean M ixture Fraction or Mixture Fraction Varianc e term.The units f or the 911Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Cell Z one C onditionsmean mix ture fraction sour ce ar e , and those f or the mix ture fraction v arianc e sour ce ar e . The defined mean mix ture fraction sour ce will app ear in the term in the tr ansp ort equa tion f or the mix ture fraction ( Equa tion 8.4 in the Theor y Guide ). The defined mix ture fraction v arianc e sour ce will app ear in the term in the tr ansp ort equa tion for the mix ture fraction v arianc e (Equa tion 8.5 in the Theor y Guide ). If you ar e using the t wo-mix ture-fraction appr oach, you c an also sp ecify sour ces of the Secondar y Mean M ixture Fraction and Secondar y M ixture Fraction Varianc e. 7.2.7.2.6. P-1 R adiation S our ces To define a sour ce for the P-1 r adia tion mo del, specify the P1 term.The units f or the r adia tion sour ce are W/ , and the defined sour ce will app ear in the term in Equa tion 5.18 in the Theor y Guide . Note tha t, if the sour ce term y ou ar e defining r epresen ts a tr ansf er fr om in ternal ener gy to radia tive ener gy (for e xample , absor ption or emission), you must sp ecify an Energy sour ce of the same magnitude as the P1 sour ce, but with the opp osite sign, in or der t o ensur e overall ener gy conser va- tion. 7.2.7.2.7. Progress Variable S our ces To define a sour ce of the pr ogress v ariable f or the pr emix ed c ombustion mo del, specify the Progress Variable term.The units f or the pr ogress v ariable sour ce ar e kg/ -s, and the defined sour ce will app ear in the term in Equa tion 9.1 in the Theor y Guide . 7.2.7.2.8. NO , HCN, and NH3 S our ces for the NO x Mo del To define a sour ce of NO , HCN, or for the NO x mo del, specify the no,hcn , or nh3 term.The units f or these sour ces ar e kg/ -s, and the defined sour ces will app ear in the , , and terms of Equa tion 14.1 ,Equa tion 14.2 , and Equa tion 14.3 in the Theor y Guide . 7.2.7.2.9. User -Defined Sc alar (UDS) S our ces You c an sp ecify sour ce term(s) f or each UDS tr ansp ort equa tion y ou ha ve defined in y our mo del. See Setting U p UDS E qua tions in ANSY S Fluen t (p.1199 ) for details . 7.3. Boundar y Conditions Boundar y conditions c onsist of e xternal, internal, and p eriodic b oundar ies. Most of the b oundar y con- ditions ar e discussed in the sec tions tha t follow. 7.3.1. Flow Inlet and Exit B oundar y Conditions 7.3.2. Using F low Boundar y Conditions 7.3.3. Pressur e Inlet B oundar y Conditions 7.3.4. Velocity Inlet B oundar y Conditions 7.3.5. Mass-F low Inlet B oundar y Conditions 7.3.6. Mass-F low Outlet B oundar y Conditions 7.3.7. Inlet Vent Boundar y Conditions 7.3.8. Intake Fan B oundar y Conditions 7.3.9. Pressur e Outlet B oundar y Conditions Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 912Cell Z one and B oundar y Conditions7.3.10. Pressur e Far-Field B oundar y Conditions 7.3.11. Outflo w Boundar y Conditions 7.3.12. Outlet Vent Boundar y Conditions 7.3.13. Exhaust F an B oundar y Conditions 7.3.14. Degassing B oundar y Conditions 7.3.15. Wall B oundar y Conditions 7.3.16. Symmetr y Boundar y Conditions 7.3.17. Periodic B oundar y Conditions 7.3.18. Axis B oundar y Conditions 7.3.19. Fan B oundar y Conditions 7.3.20. Radia tor B oundar y Conditions 7.3.21. Porous J ump B oundar y Conditions You c an find details ab out the f ollowing t ypes her e: •interface zones: Using S liding M eshes (p.1257 ) •interior z ones: Interior D ialog Box (p.3501 ) •overset z ones: Overset M eshes (p.766) •RANS/LES in terface zones: Setting U p the Emb edded Lar ge E ddy Simula tion (ELES) M odel (p.1432 ) Note By default , boundar ies ar e gr oup ed b y type, but y ou also ha ve the option of gr ouping them by: •Alphab etical (List View) •Name •Cell Z one (A djac ency) To change the gr ouping , right-click the Boundar y Conditions branch in the Outline View tree and selec t Group B y / List View or Name or Adjac enc y. Setup → Boundar y Conditions Group B y → List View | N ame | A djac enc y 7.3.1. Flow Inlet and E xit B oundar y Conditions ANSY S Fluen t has a wide r ange of b oundar y conditions tha t permit flo w to en ter and e xit the solution domain. To help y ou selec t the most appr opriate boundar y condition f or y our applic ation, this sec tion includes descr iptions of ho w each t ype of c ondition is used , and wha t inf ormation is needed f or each one . Recommenda tions f or det ermining inlet v alues of the turbulenc e par amet ers ar e also pr ovided . 7.3.2. Using F low B oundar y Conditions This sec tion pr ovides an o verview of flo w b oundar ies in ANSY S Fluen t and ho w to use them. 913Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y ConditionsANSY S Fluen t provides 12 t ypes of b oundar y zone t ypes for the sp ecific ation of flo w inlets and e xits: velocity inlet , pressur e inlet , mass-flo w inlet , mass-flo w outlet , pressur e outlet , pressur e far-field , outflo w, inlet v ent, intake fan, outlet v ent, exhaust fan, and degassing . The inlet and e xit b oundar y condition options in ANSY S Fluen t are as f ollows: •Velocity inlet b oundar y conditions ar e used t o define the v elocity and sc alar pr operties of the flo w at inlet boundar ies. •Pressur e inlet b oundar y conditions ar e used t o define the t otal pr essur e and other sc alar quan tities a t flo w inlets . •Mass-flo w inlet b oundar y conditions ar e used in c ompr essible flo ws to pr escr ibe a mass flo w rate at an inlet. It is not nec essar y to use mass-flo w inlets in inc ompr essible flo ws because when densit y is c onstan t, velocity inlet b oundar y conditions will fix the mass flo w. Like pr essur e and v elocity inlets , other inlet sc alars ar e also pr escr ibed. •Pressur e outlet b oundar y conditions ar e used t o define the sta tic pr essur e at flo w outlets (and also other scalar v ariables , in c ase of backflo w).The use of a pr essur e outlet b oundar y condition inst ead of an outflo w condition of ten r esults in a b etter rate of c onvergenc e when backflo w occurs dur ing it eration. •Pressur e far-field b oundar y conditions ar e used t o mo del a fr ee-str eam c ompr essible flo w at infinit y, with free-str eam M ach numb er and sta tic c onditions sp ecified .This b oundar y type is a vailable only f or compr ess- ible flo ws. •Outflo w boundar y conditions ar e used t o mo del flo w exits wher e the details of the flo w velocity and pressur e are not k nown pr ior t o solution of the flo w pr oblem. They are appr opriate wher e the e xit flo w is close t o a fully de velop ed c ondition, as the outflo w boundar y condition assumes a z ero str eamwise gr adien t for all flo w variables e xcept pr essur e.They are not appr opriate for compr essible flo w calcula tions . •Inlet v ent boundar y conditions ar e used t o mo del an inlet v ent with a sp ecified loss c oefficien t, flow dir ection, and ambien t (inlet) t otal pr essur e and t emp erature. •Intake fan b oundar y conditions ar e used t o mo del an e xternal in take fan with a sp ecified pr essur e jump , flow dir ection, and ambien t (in take) total pr essur e and t emp erature. •Outlet v ent boundar y conditions ar e used t o mo del an outlet v ent with a sp ecified loss c oefficien t and ambien t (dischar ge) sta tic pr essur e and t emp erature. •Exhaust fan b oundar y conditions ar e used t o mo del an e xternal e xhaust fan with a sp ecified pr essur e jump and ambien t (dischar ge) sta tic pr essur e. •Degassing b oundar y conditions ar e used t o mo del a fr ee sur face thr ough which disp ersed gas bubbles ar e allowed t o esc ape, but the c ontinuous liquid phase is not. A typic al applic ation is a bubble c olumn in which you w ant to reduc e computa tional c ost b y not including the fr eeboard region in the simula tion. The de- gassing b oundar y condition is only a vailable f or two-phase liquid-gas flo ws using the E uler ian multiphase model. 7.3.2.1. Determining Turbulenc e Paramet ers When the flo w en ters the domain a t an inlet , outlet , or far-field b oundar y, ANSY S Fluen t requir es specific ation of tr ansp orted turbulenc e quan tities .This sec tion descr ibes which quan tities ar e needed for sp ecific turbulenc e mo dels and ho w the y must b e sp ecified . It also pr ovides guidelines f or the most appr opriate way of det ermining the inflo w b oundar y values . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 914Cell Z one and B oundar y Conditions7.3.2.1.1. Specific ation of Turbulenc e Q uantities Using P rofiles If it is imp ortant to accur ately r epresen t a b oundar y layer or fully-de velop ed turbulen t flo w at the inlet , you should ideally set the turbulenc e quan tities b y creating a pr ofile file (see Profiles (p.1051 )) from e xperimen tal da ta or empir ical formulas . If you ha ve an analytic al descr iption of the pr ofile , rather than da ta p oints, you c an either use this analytic al descr iption t o cr eate a pr ofile file , or cr eate a user-defined func tion t o pr ovide the inlet b oundar y inf ormation. (See the Fluen t Customiza tion Manual for inf ormation on user-defined func tions .) Onc e you ha ve created the pr ofile func tion, you c an use it as descr ibed b elow: •Spalar t-Allmar as mo del: Choose Modified Turbulen t Visc osit y or Turbulen t Visc osit y Ratio in the Turbulenc e Specific ation M etho d drop-do wn list and selec t the appr opriate pr ofile name in the dr op- down list ne xt to Turbulen t Visc osit y or Turbulen t Visc osit y Ratio. ANSY S Fluen t comput es the boundar y value f or the mo dified turbulen t visc osity, , by combining with the appr opriate values of densit y and molecular visc osity. • - mo dels: Choose K and E psilon in the Turbulenc e Specific ation M etho d drop-do wn list and selec t the appr opriate pr ofile names in the dr op-do wn lists ne xt to Turbulen t Kinetic E nergy and Turbulen t Dissipa tion R ate. • - mo dels: Choose K and Omega in the Turbulenc e Specific ation M etho d drop-do wn list and selec t the appr opriate pr ofile names in the dr op-do wn lists ne xt to Turbulen t Kinetic E nergy and Specific Dissipa tion R ate. • -based R eynolds str ess mo dels: Choose K and E psilon in the Turbulenc e Specific ation M etho d drop- down list and selec t the appr opriate pr ofile names in the dr op-do wn lists ne xt to Turbulen t Kinetic Energy and Turbulen t Dissipa tion R ate. Choose Reynolds-S tress C omp onen ts in the Reynolds-S tress Specific ation M etho d drop-do wn list and selec t the appr opriate pr ofile name in the dr op-do wn list ne xt to each of the individual R eynolds-str ess c omp onen ts. • -based R eynolds str ess mo dels: Choose K and Omega in the Turbulenc e Specific ation M etho d drop- down list and selec t the appr opriate pr ofile names in the dr op-do wn lists ne xt to Specific D issipa tion Rate. Choose Reynolds-S tress C omp onen ts in the Reynolds-S tress S pecific ation M etho d drop-do wn list and selec t the appr opriate pr ofile name in the dr op-do wn list ne xt to each of the individual R eynolds- stress c omp onen ts. 7.3.2.1.2. Uniform Sp ecific ation of Turbulenc e Q uantities In some situa tions , it is appr opriate to sp ecify a unif orm v alue of the turbulenc e quan tity at the boundar y wher e inflo w o ccurs . Examples ar e fluid en tering a duc t, far-field b oundar ies, or e ven fully- develop ed duc t flo ws wher e accur ate pr ofiles of turbulenc e quan tities ar e unk nown. In most turbulen t flo ws, higher le vels of turbulenc e ar e gener ated within shear la yers than en ter the domain a t flo w b oundar ies, mak ing the r esult of the c alcula tion r elatively insensitiv e to the inflo w boundar y values . Nevertheless , caution must b e used t o ensur e tha t boundar y values ar e not so unph ysical as t o contamina te your solution or imp ede c onvergenc e.This is par ticular ly tr ue of e x- ternal flo ws wher e unph ysically lar ge v alues of eff ective visc osity in the fr ee str eam c an “swamp ” the b oundar y layers. You c an use the turbulenc e sp ecific ation metho ds descr ibed ab ove to en ter unif orm constan t values instead of pr ofiles . Alternatively, you c an sp ecify the turbulenc e quan tities in t erms of mor e convenien t quan tities such as turbulenc e in tensit y, turbulen t visc osity ratio, hydraulic diamet er, and turbulenc e 915Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditionslength sc ale.The default Turbulenc e Specific ation M etho d is set t o Turbulen t Visc osit y Ratio (for the S palar t-Allmar as mo del) or Intensit y and Visc osit y Ratio (for the - mo dels , the - mo dels , or the RSM). These quan tities ar e discussed fur ther in the f ollowing sec tions . 7.3.2.1.3. Turbulenc e Int ensit y The turbulenc e in tensit y, , is defined as the r atio of the r oot-mean-squar e of the v elocity fluc tuations , , to the mean flo w velocity, . A turbulenc e in tensit y of 1% or less is gener ally c onsider ed lo w and turbulenc e in tensities gr eater than 10% ar e consider ed high. Ideally , you will ha ve a go od estima te of the turbulenc e in tensit y at the inlet b oundar y from e xternal, measur ed da ta. For e xample , if y ou ar e simula ting a wind-tunnel experimen t, the turbulenc e in tensit y in the fr ee str eam is usually a vailable fr om the tunnel char ac- teristics . In mo dern lo w-turbulenc e wind tunnels , the fr ee-str eam turbulenc e in tensit y ma y be as low as 0.05%. For in ternal flo ws, the turbulenc e in tensit y at the inlets is t otally dep enden t on the upstr eam hist ory of the flo w. If the flo w upstr eam is under-de velop ed and undisturb ed, you c an use a lo w turbulenc e intensit y. If the flo w is fully de velop ed, the turbulenc e in tensit y ma y be as high as a f ew p ercent. The turbulenc e in tensit y at the c ore of a fully-de velop ed duc t flo w can b e estima ted fr om the f ollow- ing f ormula der ived fr om an empir ical correlation f or pip e flo ws: (7.66) At a R eynolds numb er of 50,000, for e xample , the turbulenc e in tensit y will b e 4%, acc ording t o this formula. The default v alue f or turbulenc e in tensit y is 5% (medium in tensit y). 7.3.2.1.4. Turbulenc e Length Sc ale and H ydraulic D iamet er The turbulenc e length sc ale, , is a ph ysical quan tity related t o the siz e of the lar ge eddies tha t contain the ener gy in turbulen t flo ws. In fully-de velop ed duc t flo ws, is restricted b y the siz e of the duc t, sinc e the turbulen t eddies c annot be lar ger than the duc t. An appr oxima te relationship b etween and the ph ysical siz e of the duc t is (7.67) wher e is the r elevant dimension of the duc t and ensur es c onsist ency with the definition of the turbulen t length sc ales f or one- and t wo-equa tion turbulenc e mo dels .The fac tor of 0.07 is based on the maximum v alue of the mixing length in fully-de velop ed turbulen t pip e flo w, wher e is the diamet er of the pip e. In a channel of non-cir cular cr oss-sec tion, you c an base on the h ydraulic diamet er. If the turbulenc e der ives its char acteristic length fr om an obstacle in the flo w, such as a p erforated plate, it is mor e appr opriate to base the turbulenc e length sc ale on the char acteristic length of the obstacle r ather than on the duc t siz e. It should b e not ed tha t the r elationship of Equa tion 7.67 (p.916), which r elates a ph ysical dimension ( ) to the turbulenc e length sc ale ( ), is not nec essar ily applic able t o all situa tions . For most c ases , however, it is a suitable appr oxima tion. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 916Cell Z one and B oundar y ConditionsGuidelines f or cho osing the char acteristic length or the turbulenc e length sc ale for selec ted flo w types ar e list ed b elow: •For fully-de velop ed in ternal flo ws, cho ose the Intensit y and H ydraulic D iamet er specific ation metho d and sp ecify the h ydraulic diamet er in the Hydraulic D iamet er field . •For flo ws do wnstr eam of tur ning v anes , perforated pla tes, and so on, cho ose the Intensit y and L ength Scale metho d and sp ecify the char acteristic length of the flo w op ening f or in the Turbulen t Length Scale field . •For w all-b ounded flo ws in which the inlets in volve a turbulen t boundar y layer, cho ose the Intensit y and Length Sc ale metho d and use the b oundar y-layer thick ness , , to comput e the turbulenc e length scale, , from . Enter this v alue f or in the Turbulenc e Length Sc ale field . 7.3.2.1.5. Turbulent Visc osit y Ratio The turbulen t visc osity ratio, , is dir ectly pr oportional t o the turbulen t Reynolds numb er ( ). is lar ge (on the or der of 100 t o 1000) in high-R eynolds-numb er b oundar y layers, shear la yers, and fully-de velop ed duc t flo ws. However, at the fr ee-str eam b oundar ies of most e xternal flows, is fair ly small. Typic ally, the turbulenc e par amet ers ar e set so tha t . For in ternal flows values up t o 100 ar e sensible f or the turbulen t visc osity ratio, .The default v alue f or the turbulen t visc osity ratio is set t o 10. To sp ecify quan tities in t erms of the turbulen t visc osity ratio, you c an cho ose Turbulen t Visc osit y Ratio (for the S palar t-Allmar as mo del) or Intensit y and Visc osit y Ratio (for the - mo dels , the - mo dels , or the RSM). The default v alue f or the turbulenc e in tensit y is set t o 5% (medium in tensit y) and the turbulen t visc osity ratio, , has a default v alue of 10. 7.3.2.1.6. Relationships for D eriving Turbulenc e Q uantities To obtain the v alues of tr ansp orted turbulenc e quan tities fr om mor e convenien t quan tities such as , , or , you must t ypic ally r esor t to an empir ical relation. Several useful r elations , most of which are used within ANSY S Fluen t, are pr esen ted b elow. 7.3.2.1.7. Estimating Mo dified Turbulent Visc osit y from Turbulenc e Int ensit y and L ength Scale To obtain the mo dified turbulen t visc osity, , for the S palar t-Allmar as mo del fr om the turbulenc e intensit y, , and length sc ale, , the f ollowing equa tion c an b e used . Note tha t this equa tion assumes that ther e is no visc ous damping , tha t is, (see Modeling the Turbulen t Viscosity in the Theor y Guide ). (7.68) This f ormula is also used in ANSY S Fluen t if y ou selec t the Intensit y and H ydraulic D iamet er spe- cific ation metho d with the S palar t-Allmar as mo del. In this c ase, is obtained fr om Equa- tion 7.67 (p.916). ensur es c onsist ency with the definition of the edd y visc osity for - and - turbulenc e mo dels .The v alue of is 0.09. 917Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions7.3.2.1.8. Estimating Turbulent K inetic E ner gy from Turbulenc e Int ensit y The r elationship b etween the turbulen t kinetic ener gy, , and turbulenc e in tensit y, , is (7.69) wher e is the mean flo w velocity. This r elationship is used in ANSY S Fluen t whene ver the Intensit y and H ydraulic D iamet er,Intensit y and L ength Sc ale, or Intensit y and Visc osit y Ratio metho d is used inst ead of sp ecifying e xplicit values f or and . 7.3.2.1.9. Estimating Turbulent D issipation R ate fr om a L ength Sc ale If you k now the turbulenc e length sc ale, , you c an det ermine from the r elationship (7.70) The det ermina tion of was discussed pr eviously . This r elationship is used in ANSY S Fluen t whene ver the Intensit y and H ydraulic D iamet er or Intensit y and L ength Sc ale metho d is used inst ead of sp ecifying e xplicit v alues f or and . 7.3.2.1.10. Estimating Turbulent D issipation R ate fr om Turbulent Visc osit y Ratio The v alue of can b e obtained fr om the turbulen t visc osity ratio and using the f ollowing r ela- tionship: (7.71) wher e is an empir ical constan t sp ecified in the turbulenc e mo del. This r elationship is used in ANSY S Fluen t whene ver the Intensit y and Visc osit y Ratio metho d is used inst ead of sp ecifying e xplicit v alues f or and . 7.3.2.1.11. Estimating Turbulent D issipation R ate for D ecaying Turbulenc e If you ar e simula ting a wind-tunnel situa tion in which the mo del is moun ted in the t est sec tion downstr eam of a mesh and/or wir e mesh scr eens , you c an cho ose a v alue of such tha t (7.72) wher e is the appr oxima te dec ay of you w ant to ha ve acr oss the flo w domain (sa y, 10% of the inlet v alue of ), is the fr ee-str eam v elocity, and is the str eamwise length of the flo w domain. Equa tion 7.72 (p.918) is a linear appr oxima tion t o the p ower-la w dec ay obser ved in high-R eynolds- numb er isotr opic turbulenc e. Its basis is the e xact equa tion f or in dec aying turbulenc e, . If you use this metho d to estima te , you should also check the r esulting turbulen t visc osity ratio to mak e sur e tha t it is not t oo lar ge, using Equa tion 7.71 (p.918). Although this metho d is not used in ternally b y ANSY S Fluen t, you c an use it t o der ive a c onstan t free-str eam v alue of tha t you c an then sp ecify dir ectly b y cho osing K and E psilon in the Turbulenc e Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 918Cell Z one and B oundar y ConditionsSpecific ation M etho d drop-do wn list. In this situa tion, you will t ypic ally det ermine from using Equa tion 7.69 (p.918). 7.3.2.1.12. Estimating Sp ecific D issipation R ate fr om a L ength Sc ale If you k now the turbulenc e length sc ale, , you c an det ermine from the r elationship (7.73) wher e is an empir ical constan t sp ecified in the turbulenc e mo del. The det ermina tion of was discussed pr eviously . This r elationship is used in ANSY S Fluen t whene ver the Intensit y and H ydraulic D iamet er or Intensit y and L ength Sc ale metho d is used inst ead of sp ecifying e xplicit v alues f or and . 7.3.2.1.13. Estimating Sp ecific D issipation R ate fr om Turbulent Visc osit y Ratio The v alue of can b e obtained fr om the turbulen t visc osity ratio and using the f ollowing r ela- tionship: (7.74) This r elationship is used in ANSY S Fluen t whene ver the Intensit y and Visc osit y Ratio metho d is used inst ead of sp ecifying e xplicit v alues f or and . 7.3.2.1.14. Estimating R eynolds Str ess C omp onents fr om Turbulent K inetic E ner gy When the RSM is used , if y ou do not sp ecify the v alues of the R eynolds str esses e xplicitly a t the inlet using the Reynolds-S tress C omp onen ts option in the Reynolds-S tress S pecific ation M etho d drop- down list , the y are appr oxima tely det ermined fr om the sp ecified v alues of .The turbulenc e is as- sumed t o be isotr opic such tha t (7.75) and (7.76) (no summa tion o ver the inde x ). ANSY S Fluen t will use this metho d if y ou selec t K or Turbulenc e In tensit y in the Reynolds-S tress Specific ation M etho d drop-do wn list. 7.3.2.1.15. Specifying Inlet Turbulenc e for LES The turbulenc e in tensit y value sp ecified a t a v elocity inlet f or LES, as descr ibed in Large E ddy Simu- lation M odel (p.1451 ), is used t o randomly p erturb the instan taneous v elocity field a t the inlet. It do es not sp ecify a mo deled turbulenc e quan tity. Inst ead, the st ochastic c omp onen ts of the flo w at the inlet b oundar y are acc oun ted f or b y sup erposing r andom p erturba tions on individual v elocity com- ponen ts as descr ibed in Inlet B oundar y Conditions f or Sc ale R esolving S imula tions in the Theor y Guide . 919Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions7.3.3. Pressur e Inlet B oundar y Conditions Pressur e inlet b oundar y conditions ar e used t o define the fluid pr essur e at flo w inlets , along with all other sc alar pr operties of the flo w.They are suitable f or b oth inc ompr essible and c ompr essible flo w calcula tions . Pressur e inlet b oundar y conditions c an b e used when the inlet pr essur e is k nown but the flow rate and/or v elocity is not k nown. This situa tion ma y ar ise in man y pr actical situa tions , including buo yancy-dr iven flo ws. Pressur e inlet b oundar y conditions c an also b e used t o define a “free” boundar y in an e xternal or unc onfined flo w. For an o verview of flo w b oundar ies, see Flow Inlet and Exit B oundar y Conditions (p.913). 7.3.3.1. Inputs at P ressur e Inlet B oundaries 7.3.3.1.1. Summar y You will en ter the f ollowing inf ormation f or a pr essur e inlet b oundar y: •type of r eference frame •total (stagna tion) pr essur e •total (stagna tion) t emp erature •flow dir ection •static pr essur e •turbulenc e par amet ers (f or turbulen t calcula tions) •radia tion par amet ers (f or calcula tions using the P-1, DTRM, DO, surface-to-sur face, or MC mo dels) •chemic al sp ecies mass or mole fr actions (f or sp ecies c alcula tions) •mixture fraction and v arianc e (for non-pr emix ed or par tially pr emix ed c ombustion c alcula tions) •progress v ariable (f or pr emix ed or par tially pr emix ed c ombustion c alcula tions) •discr ete phase b oundar y conditions (f or discr ete phase c alcula tions) •multiphase b oundar y conditions (f or gener al multiphase c alcula tions) •open channel flo w par amet ers (f or op en channel flo w calcula tions using the VOF multiphase mo del) •acoustic w ave mo del settings All values ar e en tered in the Pressur e Inlet D ialog Box (p.3524 ) (Figur e 7.31: The P ressur e Inlet D ialog Box (p.921)), which is op ened fr om the Boundar y Conditions task page (as descr ibed in Setting C ell Zone and B oundar y Conditions (p.839)). Note tha t op en channel b oundar y condition inputs ar e de- scribed in Modeling Op en C hannel F lows (p.2144 ), and ac oustic w ave mo del settings ar e descr ibed in Boundar y Acoustic Wave M odels (p.1021 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 920Cell Z one and B oundar y ConditionsFigur e 7.31: The P ressur e Inlet D ialo g Box 7.3.3.1.1.1. Pressur e Inputs and H ydrostatic H ead When gr avitational acc eleration is ac tivated in the Operating C onditions dialo g box (acc essed fr om the Boundar y Conditions task page), the pr essur e field (including all pr essur e inputs) will include the h ydrosta tic head .This is acc omplished b y redefining the pr essur e in t erms of a mo dified pr essur e that includes the h ydrosta tic head (denot ed ) as f ollows: (7.77) wher e is a c onstan t op erating densit y, is the gr avity vector (also a c onstan t), and (7.78) is the p osition v ector. Noting tha t (7.79) it follows tha t (7.80) The substitution of this r elation in the momen tum equa tion giv es pr essur e gr adien t and gr avitational body force terms of the f orm (7.81) 921Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditionswher e is the fluid densit y.Therefore, if the fluid densit y is c onstan t, we can set the op erating densit y equal t o the fluid densit y, ther eby elimina ting the b ody force term. If the fluid densit y is not c onstan t (for e xample , densit y is giv en b y the ideal gas la w), then the op erating densit y should be chosen t o be represen tative of the a verage or mean densit y in the fluid domain, so tha t the b ody force term is small. An imp ortant consequenc e of this tr eatmen t of the gr avitational b ody force is tha t your inputs of pressur e (no w defined as ) should not include h ydrosta tic pr essur e diff erences. Moreover, reports of sta tic and t otal pr essur e will not sho w an y influenc e of the h ydrosta tic pr essur e. See Natural Convection and B uoyancy-Driven F lows (p.1476 ) for additional inf ormation. 7.3.3.1.1.2. Defining Total P ressur e and Temp eratur e Enter the v alue f or total pr essur e in the Gauge Total P ressur e field in the Pressur e Inlet dialo g box.Total t emp erature is set in the Thermal tab , in the Total Temp erature field . Rememb er tha t the t otal pr essur e value is the gauge pr essur e with r espect to the op erating pr essur e defined in the Operating C onditions D ialog Box (p.3470 ).Total pr essur e for an inc ompr essible fluid is defined as (7.82) and f or a c ompr essible fluid of c onstan t as (7.83) = total pr essur e wher e = sta tic pr essur e M = M ach numb er = ratio of sp ecific hea ts If you ar e mo deling axisymmetr ic swir l, in Equa tion 7.82 (p.922) will include the swir l comp onen t. The Total Temp erature,Gauge Total P ressur e, and flo w dir ections ar e in absolut e or r elative to the adjac ent cell z one r eference frames , based on the Referenc e Frame setting in the Pressur e Inlet dialo g box. If the c ell z one adjac ent to a pr essur e inlet is defined as a mo ving r eference frame z one , and y ou are using the pr essur e-based solv er, the v elocity in Equa tion 7.82 (p.922) (or the M ach numb er in Equa tion 7.83 (p.922)) will b e absolut e or r elative to the mesh v elocity, dep ending on whether or not the Absolut e velocity formula tion is enabled in the Gener al task page . For the densit y-based solv er, the Absolut e velocity formula tion is alw ays used; henc e, the v elocity in Equa tion 7.82 (p.922) (or the M ach numb er in Equa tion 7.83 (p.922)) is alw ays the Absolut e velocity. For the E uler ian multiphase mo del, the t otal t emp erature, and v elocity comp onen ts must b e sp ecified for the individual phases .The Referenc e Frame (Rela tive to Adjac ent Cell Z one or Absolut e) for Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 922Cell Z one and B oundar y Conditionseach of the phases is the same as the r eference frame selec ted f or the mix ture phase . Note tha t the total pr essur e values must b e sp ecified in the mix ture phase . Imp ortant •If the flo w is inc ompr essible , then the t emp erature assigned in the Pressur e Inlet dialo g box will b e consider ed the sta tic t emp erature. •For the mix ture multiphase mo del, if a b oundar y allo ws a c ombina tion of c ompr essible and incompr essible phases t o en ter the domain, then the t emp erature assigned in the Pressur e Inlet dialo g box will b e consider ed the sta tic t emp erature at tha t boundar y. If a b oundar y allows only a c ompr essible phase t o en ter the domain, then the t emp erature assigned in the Pressur e Inlet dialo g box will b e tak en as the t otal t emp erature (relative/absolut e) at tha t boundar y.The t otal t emp erature will dep end on the Referenc e Frame option selec ted in the Pressur e Inlet dialo g box. •For the VOF multiphase mo del, if a b oundar y allo ws a compr essible phase to en ter the domain, then the t emp erature assigned in the Pressur e Inlet dialo g box will b e consider ed the t otal temp erature at tha t boundar y.The t otal t emp erature (relative/absolut e) will dep end on the Referenc e Frame option chosen in the dialo g box. Other wise , the t emp erature assigned t o the b oundar y will b e consider ed the sta tic t emp erature at the b oundar y. •For the E uler ian multiphase mo del, if a b oundar y allo ws a mix ture of c ompr essible and inc om- pressible phases in the domain, then the t emp erature of each of the phases will b e the t otal or sta tic t emp erature, dep ending on whether the phase is c ompr essible or inc ompr essible . •Total t emp erature (relative/absolut e) will dep end on the Referenc e Frame option chosen in the Pressur e Inlet dialo g box. 7.3.3.1.1.3. Defining the F low D irection The flo w dir ection is defined as a unit v ector ( ) which is aligned with the lo cal velocity vector, . This c an b e expressed simply as (7.84) Imp ortant For the inputs in ANSY S Fluen t, the flo w dir ection need not b e a unit v ector, as it will be aut oma tically nor maliz ed b efore it is applied . Imp ortant For a mo ving r eference frame , the r elative flo w dir ection is defined in t erms of the relative velocity, .Thus, (7.85) 923Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y ConditionsYou c an define the flo w dir ection a t a pr essur e inlet e xplicitly , or y ou c an define the flo w to be normal t o the b oundar y. If you cho ose t o sp ecify the dir ection v ector, you c an set either the (C artesian) , , and comp onen ts, or the (c ylindr ical) r adial, tangen tial, and axial c omp onen ts. For mo ving z one pr oblems c alcula ted using the pr essur e-based solv er, the flo w dir ection will b e absolut e or r elative to the mesh v elocity, dep ending on whether or not the Absolut e velocity for- mula tion is selec ted in the Gener al task page . For the densit y-based solv er, the flo w dir ection will always be in the absolut e frame . The pr ocedur e for defining the flo w dir ection is as f ollows (refer to Figur e 7.31: The P ressur e Inlet Dialog Box (p.921)): 1.Specify the flo w dir ection b y selec ting Direction Vector or Normal t o Boundar y in the Direction Specific ation M etho d drop-do wn list. 2.If you selec ted Normal t o Boundar y in st ep 1 and y ou ar e mo deling axisymmetr ic swir l, enter the ap- propriate value f or the Tangen tial-C omp onen t of F low D irection . If you chose Normal t o Boundar y and y our geometr y is 3D or 2D without axisymmetr ic swir l, ther e are no additional inputs f or flo w dir- ection. 3.If you selec ted Direction Vector in st ep 1, and y our geometr y is 3D , cho ose Cartesian (X, Y, Z),Cyl- indr ical(R adial, Tangen tial, Axial) ,Local C ylindr ical (R adial, Tangen tial, Axial) , or Local C ylindr ical Swirl from the Coordina te System drop-do wn list. Some not es on these selec tions ar e pr ovided b elow: •The Cartesian coordina te option is based on the C artesian c oordina te sy stem used b y the geometr y. Enter appr opriate values f or the X,Y, and Z-Comp onen t of F low D irection . •The Cylindr ical coordina te sy stem uses the axial, radial, and tangen tial c omp onen ts based on the following c oordina te sy stems: –For pr oblems in volving a single c ell z one , the c oordina te sy stem is defined b y the r otation axis and origin sp ecified in the Fluid D ialog Box (p.3457 ). –For pr oblems in volving multiple z ones (f or e xample , multiple r eference frames or sliding meshes), the c oordina te sy stem is defined b y the r otation axis sp ecified in the Fluid (or Solid ) dialo g box for the fluid (or solid) z one tha t is adjac ent to the inlet. For all of the ab ove definitions of the c ylindr ical coordina te sy stem, positiv e radial v elocities point radially out ward from the r otation axis , positiv e axial v elocities ar e in the dir ection of the r otation axis v ector, and p ositiv e tangen tial v elocities ar e based on the r ight-hand r ule using the p ositiv e rotation axis (see Figur e 7.32: Cylindr ical Velocity Comp onen ts in 3D , 2D, and A xisymmetr ic D omains (p.925)). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 924Cell Z one and B oundar y ConditionsFigur e 7.32: Cylindr ical Velocity Comp onen ts in 3D , 2D, and A xisymmetr ic D omains •The Local C ylindr ical coordina te sy stem allo ws you t o define a c oordina te sy stem sp ecific ally f or the inlet. When y ou use the lo cal cylindr ical option, you will define the c oordina te sy stem r ight her e in the Pressur e Inlet dialo g box.The lo cal cylindr ical coordina te sy stem is useful if y ou ha ve se veral inlets with diff erent rotation ax es. Enter appr opriate values f or the Axial ,Radial , and Tangen tial- Comp onen t of F low D irection , and then sp ecify the X,Y, and Z comp onen ts of the A xis Or igin and Axis D irection. •The Local C ylindr ical S wirl coordina te sy stem option allo ws you t o define a c oordina te sy stem specific ally f or the inlet wher e the t otal pr essur e, swir l velocity, and the c omp onen ts of the v elocity in the axial and r adial planes ar e sp ecified . Enter appr opriate values f or the Axial and Radial-C om- ponen t of F low D irection , and the Tangen tial-V elocity. Specify the X,Y, and Z comp onen ts of the Axis Or igin and A xis D irection. It is r ecommended tha t you star t your simula tion with a smaller swir l velocity and then pr ogressiv ely incr ease the v elocity to obtain a stable solution. Imp ortant Local C ylindr ical S wirl should not b e used f or op en channel b oundar y conditions and on the mixing plane b oundar ies while using the mixing plane mo del. 4.If you selec ted Direction Vector in st ep 1, and y our geometr y is 2D , define the v ector comp onen ts as follows: •For a 2D planar geometr y, enter appr opriate values f or the X,Y, and Z-Comp onen t of F low D irection . •For a 2D axisymmetr ic geometr y, enter appr opriate values f or the Axial ,Radial-C omp onen t of F low Direction . •For a 2D axisymmetr ic swir l geometr y, enter appr opriate values f or the Axial ,Radial , and Tangen tial- Comp onen t of F low D irection . Figur e 7.32: Cylindr ical Velocity Comp onen ts in 3D , 2D, and A xisymmetr ic D omains (p.925) sho ws the v ector c omp onen ts for these diff erent coordina te sy stems . 925Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions7.3.3.1.1.4. Defining Static P ressur e The sta tic pr essur e (termed the Supersonic/Initial G auge P ressur e) must b e sp ecified if the inlet flow is sup ersonic or if y ou plan t o initializ e the solution based on the pr essur e inlet b oundar y con- ditions . Solution initializa tion is discussed in Initializing the S olution (p.2604 ). Rememb er tha t the sta tic pr essur e value y ou en ter is r elative to the op erating pr essur e set in the Operating C onditions D ialog Box (p.3470 ). Note the c ommen ts in Pressur e Inputs and H ydrosta tic Head (p.921) regar ding h ydrosta tic pr essur e. The Supersonic/Initial G auge P ressur e is ignor ed b y ANSY S Fluen t whene ver the flo w is subsonic , in which c ase it is c alcula ted fr om the sp ecified stagna tion quan tities . If you cho ose t o initializ e the solution based on the pr essur e-inlet c onditions , the Supersonic/Initial G auge P ressur e will b e used in conjunc tion with the sp ecified stagna tion pr essur e to comput e initial v alues acc ording t o the is- entropic r elations (f or c ompr essible flo w) or B ernoulli ’s equa tion (f or inc ompr essible flo w).Therefore, for a sub-sonic inlet it should gener ally b e set based on a r easonable estima te of the inlet M ach numb er (f or c ompr essible flo w) or inlet v elocity (for inc ompr essible flo w). 7.3.3.1.1.5. Prevent R everse F low When this option is selec ted, Fluen t will er ect artificial w alls on the b oundar y mesh fac es to pr event flow out of the domain. The ar tificial w alls ar e remo ved when the flo w is no longer lea ving the domain and when a fa vorable pr essur e gr adien t is r ecovered a t the b oundar y mesh fac es. When ar tificial w alls ar e created, Fluen t will pr int a message in the c onsole windo w indic ating the numb er of fac es on which ar tificial w alls ha ve been er ected and the equiv alen t area p ercentage of the b oundar y it r epresen ts. Note This f eature is not a vailable with multiphase flo w. 7.3.3.1.1.6. Defining Turbulenc e Paramet ers For turbulen t calcula tions , ther e ar e se veral w ays in which y ou c an define the turbulenc e par amet ers. Instr uctions f or deciding which metho d to use and det ermining appr opriate values f or these inputs are pr ovided in Determining Turbulenc e Paramet ers (p.914).Turbulenc e mo deling in gener al is de- scribed in Modeling Turbulenc e (p.1375 ). 7.3.3.1.1.7. Defining R adiation P aramet ers If you ar e using the P-1, DTRM, DO , sur face-to-sur face, or MC mo dels , you will set the Internal Emissivit y and (optionally) External Black B ody Temp erature. See Defining B oundar y Conditions for R adia tion (p.1514 ) for details . (The R osseland r adia tion mo del do es not r equir e an y boundar y condition inputs .) 7.3.3.1.1.8. Defining Sp ecies M ass or Mole F ractions If you ar e mo deling sp ecies tr ansp ort, you will set the sp ecies mass or mole fr actions under Species Mole F ractions or Species M ass F ractions . For details , see Defining C ell Z one and B oundar y Condi- tions f or S pecies (p.1649 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 926Cell Z one and B oundar y Conditions7.3.3.1.1.9. Defining N on-P remix ed C ombustion P aramet ers If you ar e using the non-pr emix ed or par tially pr emix ed c ombustion mo del, you will set the Mean Mixture Fraction and Mixture Fraction Varianc e (and the Secondar y M ean M ixture Fraction and Secondar y M ixture Fraction Varianc e, if y ou ar e using t wo mix ture fractions), as descr ibed in De- fining N on-P remix ed B oundar y Conditions (p.1739 ). 7.3.3.1.1.10. Defining P remix ed C ombustion B oundar y Conditions If you ar e using the pr emix ed or par tially pr emix ed c ombustion mo del, you will set the Progress Variable , as descr ibed in Setting B oundar y Conditions f or the P rogress Variable (p.1754 ). 7.3.3.1.1.11. Defining D iscr ete Phase B oundar y Conditions If you ar e mo deling a discr ete phase of par ticles , you c an set the fa te of par ticle tr ajec tories a t the pressur e inlet. See Setting B oundar y Conditions f or the D iscrete Phase (p.1985 ) for details . 7.3.3.1.1.12. Defining Multiphase B oundar y Conditions If you ar e using the VOF, mix ture, or E uler ian mo del f or multiphase flo w, you will need t o sp ecify volume fr actions f or sec ondar y phases and (f or some mo dels) additional par amet ers. See Defining Multiphase C ell Z one and B oundar y Conditions (p.2124 ) for details . 7.3.3.1.1.13. Defining O pen C hannel B oundar y Conditions If you ar e using the VOF mo del f or multiphase flo w and mo deling op en channel flo ws, you will need to sp ecify the Free S urface Level,Bottom L evel, and additional par amet ers. See Modeling Op en Channel F lows (p.2144 ) for details . 7.3.3.2. Default S ettings at P ressur e Inlet B oundaries Default settings (in SI) f or pr essur e inlet b oundar y conditions ar e as f ollows: 0 Gauge Total P ressur e 0 Supersonic/Initial G auge P ressur e 300 Total Temp erature Normal t o Boundar yDirection S pecific ation M etho d 5% Turbulen t In tensit y 10 Turbulen t Visc osit y Ratio 7.3.3.3. Calculation P rocedur e at P ressur e Inlet B oundaries The tr eatmen t of pr essur e inlet b oundar y conditions b y ANSY S Fluen t can b e descr ibed as a loss-fr ee transition fr om stagna tion c onditions t o the inlet c onditions . For inc ompr essible flo ws, this is acc om- plished b y applic ation of the B ernoulli equa tion a t the inlet b oundar y. In c ompr essible flo ws, the equiv alen t isen tropic flo w relations f or an ideal gas ar e used . 927Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions7.3.3.3.1. Inc ompr essible F low C alculations at P ressur e Inlet B oundaries When flo w en ters thr ough a pr essur e inlet b oundar y, ANSY S Fluen t uses the b oundar y condition pressur e you input as the t otal pr essur e of the fluid a t the inlet plane , . In inc ompr essible flo w, the inlet t otal pr essur e and the sta tic pr essur e, , are related t o the inlet v elocity via B ernoulli ’s equa tion: (7.86) With the r esulting v elocity magnitude and the flo w dir ection v ector y ou assigned a t the inlet , the velocity comp onen ts can b e comput ed.The inlet mass flo w rate and flux es of momen tum, ener gy, and sp ecies c an then b e comput ed as outlined in Calcula tion P rocedur e at Velocity Inlet B oundar- ies (p.934). For inc ompr essible flo ws, densit y at the inlet plane is either c onstan t or c alcula ted as a func tion of temp erature and/or sp ecies mass/mole fr actions , wher e the mass or mole fr actions ar e the v alues you en tered as an inlet c ondition. If flo w exits thr ough a pr essur e inlet , the t otal pr essur e sp ecified is used as the sta tic pr essur e. For incompr essible flo ws, total t emp erature is equal t o sta tic t emp erature. 7.3.3.3.2. Compr essible F low C alculations at P ressur e Inlet B oundaries In compr essible flo ws, isen tropic r elations f or an ideal gas ar e applied t o relate total pr essur e, static pressur e, and v elocity at a pr essur e inlet b oundar y.Your input of t otal pr essur e, , at the inlet and the sta tic pr essur e, , in the adjac ent fluid c ell ar e ther efore related as (7.87) wher e (7.88) = the sp eed of sound , and . Note tha t the op erating pr essur e, , app ears in Equa- tion 7.87 (p.928) because y our b oundar y condition inputs ar e in t erms of pr essur e relative to the operating pr essur e. Given and ,Equa tion 7.87 (p.928) and Equa tion 7.88 (p.928) are used t o comput e the v elocity magnitude of the fluid a t the inlet plane . Individual v elocity comp onen ts at the inlet ar e then der ived using the dir ection v ector c omp onen ts. For c ompr essible flo w, the densit y at the inlet plane is defined b y the ideal gas la w in the f orm (7.89) For multi-sp ecies gas mix tures, the sp ecific gas c onstan t, , is c omput ed fr om the sp ecies mass or mole fr actions , tha t you defined as b oundar y conditions a t the pr essur e inlet b oundar y.The static t emp erature at the inlet , , is c omput ed fr om y our input of t otal t emp erature, , as (7.90) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 928Cell Z one and B oundar y Conditions7.3.4. Velocity Inlet B oundar y Conditions Velocity inlet b oundar y conditions ar e used t o define the flo w velocity, along with all r elevant scalar properties of the flo w, at flo w inlets . In this c ase, the t otal (or stagna tion) pr essur e is not fix ed but will rise (in r esponse t o the c omput ed sta tic pr essur e) to wha tever v alue is nec essar y to pr ovide the pr e- scribed v elocity distr ibution. This b oundar y condition is applic able t o inc ompr essible and c ompr essible flows. Imp ortant Use c aution when sp ecifying the v elocity inlet b oundar y condition f or a c ompr essible fluid in in ternal flo w mo deling . If the flo w pa th is c omplet ely chok ed with no sec ondar y flo w path for relief , the v elocity inlet b oundar y condition is not r ecommended , as it c an c ause numer ical instabilities . In this c ase, you should swit ch t o the pr essur e inlet b oundar y condition or refrain fr om r eaching op erating c onditions tha t chok e the in ternal flo w.The chok ing condition c an happ en in high sp eed sup ersonic and tr ansonic flo w. In sp ecial instanc es, a velocity inlet ma y be used in ANSY S Fluen t to define the flo w velocity at flo w exits. (The sc alar inputs ar e not used in such c ases .) In such c ases y ou must ensur e tha t overall c ontinuit y is main tained in the domain. For an o verview of flo w b oundar ies, see Flow Inlet and Exit B oundar y Conditions (p.913). 7.3.4.1. Inputs at Velocity Inlet B oundaries 7.3.4.1.1. Summar y You will en ter the f ollowing inf ormation f or a v elocity inlet b oundar y: •type of r eference frame •velocity magnitude and dir ection or v elocity comp onen ts •swir l velocity (for 2D axisymmetr ic pr oblems with swir l) •static pr essur e •temp erature (for ener gy calcula tions) •outflo w gauge pr essur e (for calcula tions with the densit y-based solv er) •turbulenc e par amet ers (f or turbulen t calcula tions) •radia tion par amet ers (f or calcula tions using the P-1, DTRM, DO, surface-to-sur face, or MC mo dels) •chemic al sp ecies mass or mole fr actions (f or sp ecies c alcula tions) •mixture fraction and v arianc e (for non-pr emix ed or par tially pr emix ed c ombustion c alcula tions) •progress v ariable (f or pr emix ed or par tially pr emix ed c ombustion c alcula tions) •discr ete phase b oundar y conditions (f or discr ete phase c alcula tions) •multiphase b oundar y conditions (f or gener al multiphase c alcula tions) 929Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions•acoustic w ave mo del settings (see Boundar y Acoustic Wave Models (p.1021 )) All values ar e en tered in the Velocity Inlet D ialog Box (p.3540 ) (Figur e 7.33: The Velocity Inlet D ialog Box (p.930)), which is op ened fr om the Boundar y Conditions task page (as descr ibed in Setting C ell Zone and B oundar y Conditions (p.839)). Note tha t acoustic w ave mo del settings ar e descr ibed in Boundar y Acoustic Wave M odels (p.1021 ). Figur e 7.33: The Velocity Inlet D ialo g Box 7.3.4.1.2. Defining the Velocity You c an define the inflo w velocity by sp ecifying the v elocity magnitude and dir ection, the v elocity comp onen ts, or the v elocity magnitude nor mal t o the b oundar y. If the c ell z one adjac ent to the velocity inlet is mo ving (tha t is, if y ou ar e using a mo ving r eference frame , multiple r eference frames , or sliding meshes), you c an sp ecify either r elative or absolut e velocities . For axisymmetr ic pr oblems with swir l in ANSY S Fluen t, you will also sp ecify the swir l velocity. The pr ocedur e for defining the inflo w velocity is as f ollows: 1.Specify the flo w dir ection b y selec ting Magnitude and D irection ,Comp onen ts, or Magnitude , Normal to Boundar y in the Velocity Specific ation M etho d drop-do wn list. 2.If the c ell z one adjac ent to the v elocity inlet is mo ving , you c an cho ose t o sp ecify r elative or absolut e velocities b y selec ting Rela tive to Adjac ent Cell Z one or Absolut e in the Referenc e Frame drop-do wn list. If the adjac ent cell z one is not mo ving ,Absolut e and Rela tive to Adjac ent Cell Z one will b e equiv alen t, so y ou need not visit the list. 3.If you ar e going t o set the v elocity magnitude and dir ection or the v elocity comp onen ts, and y our geometr y is 3D , cho ose Cartesian (X, Y, Z),Cylindr ical (R adial, Tangen tial, Axial) , or Local C ylindr ical Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 930Cell Z one and B oundar y Conditions(Radial, Tangen tial, Axial) from the Coordina te System drop-do wn list. See Defining the F low D irec- tion (p.923) for inf ormation ab out C artesian, cylindr ical, and lo cal cylindr ical coordina te sy stems . 4.Set the appr opriate velocity par amet ers, as descr ibed b elow for each sp ecific ation metho d. 7.3.4.1.3. Setting the Velocity M agnitude and D irection If you selec ted Magnitude and D irection as the Velocity Specific ation M etho d in st ep 1 ab ove, you will en ter the magnitude of the v elocity vector a t the inflo w b oundar y (the Velocity M agnitude ) and the dir ection of the v ector: •If your geometr y is 2D non-axisymmetr ic, or y ou chose in st ep 3 t o use the Cartesian coordina te sy stem, you will define the X,Y, and (in 3D) Z-Comp onen t of F low D irection . •If your geometr y is 2D axisymmetr ic, or y ou chose in st ep 3 t o use a Cylindr ical coordina te sy stem, enter the appr opriate values of Radial ,Axial , and (if y ou ar e mo deling axisymmetr ic swir l or using c ylindr ical coordina tes) Tangen tial-C omp onen t of F low D irection . •If you chose in st ep 3 t o use a Local C ylindr ical coordina te sy stem, enter appr opriate values f or the Axial ,Radial , and Tangen tial-C omp onen t of F low D irection , and then sp ecify the X,Y, and Z comp on- ents of the Axis Or igin and the Axis D irection . Figur e 7.32: Cylindr ical Velocity Comp onen ts in 3D , 2D, and A xisymmetr ic D omains (p.925) sho ws the v ector c omp onen ts for these diff erent coordina te sy stems . 7.3.4.1.4. Setting the Velocity M agnitude N ormal t o the B oundar y If you selec ted Magnitude , Normal t o Boundar y as the Velocity Specific ation M etho d in st ep 1 above, you will en ter the magnitude of the v elocity vector a t the inflo w b oundar y (the Velocity Magnitude ). 7.3.4.1.5. Setting the Velocity Comp onents If you selec ted Comp onen ts as the Velocity Specific ation M etho d in st ep 1 ab ove, you will en ter the c omp onen ts of the v elocity vector a t the inflo w b oundar y as f ollows: •If your geometr y is 2D non-axisymmetr ic, or y ou chose in st ep 3 t o use the C artesian c oordina te sy stem, you will define the X,Y, and (in 3D) Z-Velocity. •If your geometr y is 2D axisymmetr ic without swir l, you will set the Radial and Axial-V elocity. •If your mo del is 2D axisymmetr ic with swir l, you will set the Axial ,Radial , and Swirl-Velocity, and (op- tionally) the Angular Velocity, as descr ibed b elow. •If you chose in st ep 3 t o use a Cylindr ical coordina te sy stem, you will set the Radial ,Tangen tial, and Axial-V elocity, and (optionally) the Angular Velocity, as descr ibed b elow. 931Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions•If you chose in st ep 3 t o use a Local C ylindr ical coordina te sy stem, you will set the Radial ,Tangen tial, and Axial-V elocity, and (optionally) the Angular Velocity, as descr ibed b elow, and then sp ecify the X, Y, and Z comp onen t of the Axis Or igin and the Axis D irection . Imp ortant Rememb er tha t positiv e values f or , , and velocities indic ate flo w in the p ositiv e , , and directions . If flo w en ters the domain in the nega tive direction, for e xample , you will need t o sp ecify a nega tive value f or the velocity.The same holds tr ue f or the radial, tangen tial, and axial v elocities . Positiv e radial v elocities p oint radially out fr om the axis, positiv e axial v elocities ar e in the dir ection of the axis v ector, and p ositiv e tangen tial velocities ar e based on the r ight-hand r ule using the p ositiv e axis . 7.3.4.1.6. Setting the A ngular Velocity If you chose Comp onen ts as the Velocity Specific ation M etho d in st ep 1 ab ove, and y ou ar e modeling axisymmetr ic swir l, you c an sp ecify the inlet Angular Velocity in addition t o the Swirl- Velocity. Similar ly, if y ou chose Comp onen ts as the Velocity Specific ation M etho d and y ou chose in st ep 3 t o use a Cylindr ical or Local C ylindr ical coordina te sy stem, you c an sp ecify the inlet An- gular Velocity in addition t o the Tangen tial-V elocity. If you sp ecify , is c omput ed f or each fac e as , wher e is the r adial c oordina te in the c oordina te system defined b y the r otation axis and or igin. If you sp ecify b oth the Swirl-Velocity and the Angular Velocity, or the Tangen tial-V elocity and the Angular Velocity, ANSY S Fluen t will add and to get the swir l or tangen tial v elocity at each fac e. 7.3.4.1.7. Defining Static P ressur e The sta tic pr essur e (termed the Supersonic/Initial G auge P ressur e) must b e sp ecified if the inlet flow is sup ersonic or if y ou plan t o initializ e the solution based on the v elocity inlet b oundar y con- ditions . Solution initializa tion is discussed in Initializing the S olution (p.2604 ). The Supersonic/Initial G auge P ressur e is ignor ed b y ANSY S Fluen t whene ver the flo w is subsonic . If you cho ose t o initializ e the flo w based on the v elocity inlet c onditions , the Supersonic/Initial Gauge P ressur e will b e used in c onjunc tion with the sp ecified stagna tion quan tities t o comput e initial v alues acc ording t o isen tropic r elations . Rememb er tha t the sta tic pr essur e value y ou en ter is r elative to the op erating pr essur e set in the Operating C onditions D ialog Box (p.3470 ). Note the c ommen ts in Pressur e Inputs and H ydrosta tic Head (p.921) 7.3.4.1.8. Defining the Temp eratur e For c alcula tions in which the ener gy equa tion is b eing solv ed, you will set the sta tic t emp erature of the flo w at the v elocity inlet b oundar y in the Thermal tab in the Temp erature field . 7.3.4.1.9. Defining O utflo w G auge P ressur e If you ar e using the densit y-based solv er, you c an sp ecify an Outflo w G auge P ressur e for a v elocity inlet b oundar y. If the flo w exits the domain a t an y fac e on the b oundar y, tha t fac e will b e treated as a pr essur e outlet with the pr essur e pr escr ibed in the Outflo w G auge P ressur e field . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 932Cell Z one and B oundar y Conditions7.3.4.1.10. Defining Turbulenc e Paramet ers For turbulen t calcula tions , ther e ar e se veral w ays in which y ou c an define the turbulenc e par amet ers. Instr uctions f or deciding which metho d to use and det ermining appr opriate values f or these inputs are pr ovided in Determining Turbulenc e Paramet ers (p.914).Turbulenc e mo deling in gener al is de- scribed in Modeling Turbulenc e (p.1375 ). 7.3.4.1.11. Defining R adiation P aramet ers If you ar e using the P-1, DTRM, DO , sur face-to-sur face, or MC mo dels , you will set the Internal Emissivit y and (optionally) External Black B ody Temp erature. See Defining B oundar y Conditions for R adia tion (p.1514 ) for details . (The R osseland r adia tion mo del do es not r equir e an y boundar y condition inputs .) 7.3.4.1.12. Defining Sp ecies M ass or Mole F ractions If you ar e mo deling sp ecies tr ansp ort, you will set the sp ecies mass or mole fr actions under Species Mole F ractions or Species M ass F ractions . For details , see Defining C ell Z one and B oundar y Condi- tions f or S pecies (p.1649 ). 7.3.4.1.13. Defining N on-P remix ed C ombustion P aramet ers If you ar e using the non-pr emix ed or par tially pr emix ed c ombustion mo del, you will set the Mean Mixture Fraction and Mixture Fraction Varianc e (and the Secondar y M ean M ixture Fraction and Secondar y M ixture Fraction Varianc e, if y ou ar e using t wo mix ture fractions), as descr ibed in De- fining N on-P remix ed B oundar y Conditions (p.1739 ). 7.3.4.1.14. Defining P remix ed C ombustion B oundar y Conditions If you ar e using the pr emix ed or par tially pr emix ed c ombustion mo del, you will set the Progress Variable , as descr ibed in Setting B oundar y Conditions f or the P rogress Variable (p.1754 ). 7.3.4.1.15. Defining D iscr ete Phase B oundar y Conditions If you ar e mo deling a discr ete phase of par ticles , you c an set the fa te of par ticle tr ajec tories a t the velocity inlet. See Setting B oundar y Conditions f or the D iscrete Phase (p.1985 ) for details . 7.3.4.1.16. Defining Multiphase B oundar y Conditions If you ar e using the VOF, mix ture, or E uler ian mo del f or multiphase flo w, you will need t o sp ecify volume fr actions f or sec ondar y phases and (f or some mo dels) additional par amet ers. See Defining Multiphase C ell Z one and B oundar y Conditions (p.2124 ) for details . 7.3.4.2. Default S ettings at Velocity Inlet B oundaries Default settings (in SI) f or v elocity inlet b oundar y conditions ar e as f ollows: 300 Temp erature 0 Velocity M agnitude 1 X-C omp onen t of F low D irection 0 Y-C omp onen t of F low D irection 0 Z-Comp onen t of F low D irection 933Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions0 X-V elocity 0 Y-V elocity 0 Z-Velocity 5% Turbulen t In tensit y 10 Turbulen t Visc osit y Ratio 0 Outflo w G auge P ressur e 7.3.4.3. Calculation P rocedur e at Velocity Inlet B oundaries ANSY S Fluen t uses y our b oundar y condition inputs a t velocity inlets t o comput e the mass flo w in to the domain thr ough the inlet and t o comput e the flux es of momen tum, ener gy, and sp ecies thr ough the inlet. This sec tion descr ibes these c alcula tions f or the c ase of flo w en tering the domain thr ough the v elocity inlet b oundar y and f or the less c ommon c ase of flo w exiting the domain thr ough the velocity inlet b oundar y. 7.3.4.3.1. Treatment of Velocity Inlet C onditions at F low Inlets When y our v elocity inlet b oundar y condition defines flo w en tering the ph ysical domain of the model, ANSY S Fluen t uses b oth the v elocity comp onen ts and the sc alar quan tities tha t you defined as b oundar y conditions t o comput e the inlet mass flo w rate, momen tum flux es, and flux es of ener gy and chemic al sp ecies . The mass flo w rate en tering a fluid c ell adjac ent to a v elocity inlet b oundar y is c omput ed as (7.91) Note tha t only the v elocity comp onen t nor mal t o the c ontrol volume fac e contribut es to the inlet mass flo w rate. 7.3.4.3.2. Treatment of Velocity Inlet C onditions at F low E xits Sometimes a v elocity inlet b oundar y is used wher e flo w exits the ph ysical domain. This appr oach migh t be used , for e xample , when the flo w rate thr ough one e xit of the domain is k nown or is t o be imp osed on the mo del. Imp ortant In such c ases y ou must ensur e tha t overall c ontinuit y is main tained in the domain. In the pr essur e-based solv er, when flo w exits the domain thr ough a v elocity inlet b oundar y ANSY S Fluen t uses the b oundar y condition v alue f or the v elocity comp onen t nor mal t o the e xit flo w ar ea. It do es not use an y other b oundar y conditions tha t you ha ve input. Inst ead, all flo w conditions e xcept the nor mal v elocity comp onen t are assumed t o be those of the upstr eam c ell. In the densit y-based solv er, if the flo w exits the domain a t an y fac e on the b oundar y, tha t fac e will be treated as a pr essur e outlet with the pr essur e pr escr ibed in the Outflo w G auge P ressur e field . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 934Cell Z one and B oundar y Conditions7.3.4.3.3. Densit y Calculation Densit y at the inlet plane is either c onstan t or c alcula ted as a func tion of t emp erature, pressur e, and/or sp ecies mass/mole fr actions , wher e the mass or mole fr actions ar e the v alues y ou en tered as an inlet c ondition. 7.3.5. Mass-F low Inlet B oundar y Conditions Mass flo w b oundar y conditions c an b e used in ANSY S Fluen t to pr ovide a pr escr ibed mass flo w rate or mass flux distr ibution a t an inlet. As with a v elocity inlet , specifying the mass flux p ermits the t otal pressur e to vary in r esponse t o the in terior solution. This is in c ontrast t o the pr essur e inlet b oundar y condition (see Pressur e Inlet B oundar y Conditions (p.920)), wher e the t otal pr essur e is fix ed while the mass flux v aries.The mass-flo w inlet is applic able t o inc ompr essible and c ompr essible flo ws. Imp ortant Use c aution when sp ecifying the mass-flo w inlet b oundar y condition f or a c ompr essible fluid in in ternal flo w mo deling . If the flo w pa th is c omplet ely chok ed with no sec ondar y flow pa th for relief , the mass-flo w inlet b oundar y condition is not r ecommended , as it c an cause numer ical instabilities . In this c ase, you should swit ch t o the pr essur e inlet b oundar y condition or r efrain fr om r eaching op erating c onditions tha t chok e the in ternal flo w.The chok ing c ondition c an happ en in high sp eed sup ersonic and tr ansonic flo w. A mass-flo w inlet is of ten used when it is mor e imp ortant to ma tch a pr escr ibed mass flo w rate than to ma tch the t otal pr essur e of the inflo w str eam. An example is the c ase of a small c ooling jet tha t is bled in to the main flo w at a fix ed mass flo w rate, while the v elocity of the main flo w is go verned primar ily b y a (diff erent) pr essur e inlet/outlet b oundar y condition pair . A mass-flo w inlet b oundar y condition c an also b e used as an outflo w b y sp ecifying the flo w dir ection a way from the solution domain. 7.3.5.1. Limitations and Sp ecial C onsider ations •The adjustmen t of inlet t otal pr essur e migh t result in a slo wer convergenc e, so if b oth the pr essur e inlet boundar y condition and the mass-flo w inlet b oundar y condition ar e acc eptable choic es, you should choose the f ormer . •It is not nec essar y to use mass-flo w inlets in inc ompr essible flo ws because when densit y is c onstan t, velocity inlet b oundar y conditions will fix the mass flo w. For an o verview of flo w b oundar ies, see Flow Inlet and Exit B oundar y Conditions (p.913). 7.3.5.2. Inputs at M ass-F low Inlet B oundaries 7.3.5.2.1. Summar y You will en ter the f ollowing inf ormation f or a mass-flo w inlet b oundar y: •type of r eference frame •mass flo w rate, mass flux, or (pr imar ily for the mixing plane mo del) mass flux with a verage mass flux •total (stagna tion) t emp erature 935Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions•static pr essur e •flow dir ection •turbulenc e par amet ers (f or turbulen t calcula tions) •radia tion par amet ers (f or calcula tions using the P-1, DTRM, DO, surface-to-sur face, or MC mo dels) •chemic al sp ecies mass or mole fr actions (f or sp ecies c alcula tions) •mixture fraction and v arianc e (for non-pr emix ed or par tially pr emix ed c ombustion c alcula tions) •progress v ariable (f or pr emix ed or par tially pr emix ed c ombustion c alcula tions) •discr ete phase b oundar y conditions (f or discr ete phase c alcula tions) •open channel flo w par amet ers (f or op en channel flo w calcula tions using the VOF multiphase mo del) •acoustic w ave mo del settings All values ar e en tered in the Mass-F low Inlet D ialog Box (p.3502 ) (Figur e 7.34: The M ass-F low Inlet Dialog Box (p.936)), which is op ened fr om the Boundar y Conditions task page (as descr ibed in Setting C ell Z one and B oundar y Conditions (p.839)). Note tha t op en channel b oundar y condition inputs ar e descr ibed in Modeling Op en C hannel F lows (p.2144 ), and ac oustic w ave mo del settings are descr ibed in Boundar y Acoustic Wave M odels (p.1021 ). Figur e 7.34: The M ass-F low Inlet D ialo g Box Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 936Cell Z one and B oundar y Conditions7.3.5.2.2. Selec ting the R efer enc e Frame You will ha ve the option t o sp ecify the mass flo w b oundar y conditions either in the absolut e or r el- ative reference frame , when the c ell z one adjac ent to the mass-flo w inlet is mo ving . For such a c ase, choose Absolut e (the default) or Rela tive to Adjac ent Cell Z one in the Referenc e Frame drop- down list. If the c ell z one adjac ent to the mass-flo w inlet is not mo ving , both f ormula tions ar e equiv alen t. 7.3.5.2.3. Defining the M ass F low R ate or M ass F lux You c an sp ecify the mass flo w rate thr ough the inlet z one and ha ve ANSY S Fluen t convert this v alue to mass flux, or sp ecify the mass flux dir ectly. For c ases wher e the mass flux v aries acr oss the boundar y, you c an also sp ecify an a verage mass flux; see b elow for mor e inf ormation ab out this specific ation metho d. You c an define the mass flux or mass flo w rate using a pr ofile or a user-defined func tion. The inputs f or mass flo w rate or flux ar e as f ollows: 1.Make a selec tion in the Mass F low S pecific ation M etho d drop-do wn list t o sp ecify whether y ou will define a Mass F low R ate,Mass F lux, or Mass F lux with A verage M ass F lux. 2.If you selec ted Mass F low R ate (the default), enter the pr escr ibed Mass F low R ate when constan t is selec ted fr om the dr op-do wn list. Other wise , selec t your ho oked user-defined func tion (UDF) or tr ansien t profile . Imp ortant The ho oked UDF or tr ansien t profile c an only b e used t o pr ovide time-v arying sp ecific- ation of mass flo w rate.Therefore, the tr ansien t solv er must b e used t o run the simu- lation. Note tha t the v ariation of pr ofile with p osition in spac e is not applic able with this ho okup. See DEFINE_PROFILE in the Fluen t Customiza tion M anual for an e xample of a mass-flo w inlet UDF . Imp ortant Note tha t for axisymmetr ic pr oblems , this mass flo w rate is the flo w rate thr ough the entire ( -radian) domain, not thr ough a 1-r adian slic e. 3.If you selec ted Mass F lux, enter the pr escr ibed Mass F lux, or selec t your ho oked UDF or pr ofile . 4.If you selec ted Mass F lux with A verage M ass F lux, enter the pr escr ibed Mass F lux and Average M ass Flux. Imp ortant Note tha t for axisymmetr ic pr oblems , the Mass F lux and Average M ass F lux is the flux through a 1-r adian slic e of the domain. 937Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions7.3.5.2.4. Mor e About M ass F lux and A verage M ass F lux As not ed pr eviously , you c an sp ecify an a verage mass flux with the mass flux. If, for e xample , you specify a mass flux pr ofile such tha t the a verage mass flux in tegrated o ver the z one ar ea is 4.7, but you ac tually w ant to ha ve a t otal mass flux of 5, you c an k eep the pr ofile unchanged , and sp ecify an a verage mass flux of 5. ANSY S Fluen t will main tain the pr ofile shap e but adjust the v alues so tha t the r esulting mass flux acr oss the b oundar y is 5. The mass flux with a verage mass flux sp ecific ation metho d is also used b y the mixing plane mo del descr ibed in The M ixing P lane M odel (p.1239 ). If the mass-flo w inlet b oundar y is going t o represen t one of the mixing planes , then y ou do not need t o sp ecify the mass flux or flo w rate; you c an k eep the default Mass F low R ate of 1. When y ou cr eate the mixing plane la ter on in the pr oblem setup , ANSY S Fluen t will aut oma tically selec t the Mass F lux with A verage M ass F lux metho d in the Mass- Flow Inlet dialo g box and set the Average M ass F lux to the v alue obtained b y integrating the mass flux pr ofile f or the upstr eam z one .This will ensur e tha t mass is c onser ved b etween the upstr eam zone and the do wnstr eam (mass-flo w inlet) z one . 7.3.5.2.5. Defining the Total Temp eratur e Enter the v alue f or the t otal (stagna tion) t emp erature of the inflo w str eam in the Total Temp erature field in the Thermal tab . The t otal t emp erature is sp ecified either in the absolut e reference frame or r elative to the adjac ent cell z one , dep ending on y our setting f or the Referenc e Frame . For the E uler ian multiphase mo del, the t otal t emp erature, and mass flux c omp onen ts need t o be specified f or the individual phases .The Referenc e Frame (Rela tive to Adjac ent Cell Z one or Abso- lute) for each of the phases is the same as the r eference frame selec ted f or the mix ture phase . Imp ortant Note tha t you c an only set the r eference frame f or the mix ture, however, the t otal t em- perature can only b e set f or the individual phases . Imp ortant •If the flo w is inc ompr essible , then the t emp erature assigned in the Mass-F low Inlet dialo g box is c onsider ed t o be the sta tic t emp erature. •For the mix ture multiphase mo del, if a b oundar y allo ws a c ombina tion of c ompr essible and incompr essible phases t o en ter the domain, then the t emp erature assigned in the Mass-F low Inlet dialo g box is c onsider ed t o be the sta tic t emp erature at tha t boundar y. If a b oundar y allows only a c ompr essible phase to en ter the domain, then the t emp erature assigned in the Mass-F low Inlet dialo g box is the t otal t emp erature (relative/absolut e) at tha t boundar y.The total t emp erature dep ends on the Referenc e Frame option selec ted in the Mass-F low Inlet dialo g box. •For the VOF multiphase mo del, if a b oundar y allo ws a compr essible phase to en ter the domain, then the t emp erature assigned in the Mass-F low Inlet dialo g box is c onsider ed t o be the total t emp erature at tha t boundar y.The t otal t emp erature (relative/absolut e) dep ends on the Referenc e Frame option chosen in the dialo g box. Other wise , the t emp erature assigned t o the b oundar y is c onsider ed t o be the sta tic t emp erature at the b oundar y. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 938Cell Z one and B oundar y Conditions•For the E uler ian multiphase mo del, if a b oundar y allo ws a mix ture of c ompr essible and inc om- pressible phases in the domain, then the t emp erature of each of the phases is the t otal or static t emp erature, dep ending on whether the phase is c ompr essible or inc ompr essible .Total temp erature (relative/absolut e) dep ends on the Referenc e Frame option chosen in the Mass- Flow Inlet dialo g box. 7.3.5.2.6. Defining Static P ressur e The sta tic pr essur e (termed the Supersonic/Initial G auge P ressur e) must b e sp ecified if the inlet flow is sup ersonic or if y ou plan t o initializ e the solution based on the pr essur e inlet b oundar y con- ditions . Solution initializa tion is discussed in Initializing the S olution (p.2604 ). The Supersonic/Initial G auge P ressur e is ignor ed b y ANSY S Fluen t whene ver the flo w is subsonic . If you cho ose t o initializ e the flo w based on the mass-flo w inlet c onditions , the Supersonic/Initial Gauge P ressur e will b e used in c onjunc tion with the sp ecified stagna tion quan tities t o comput e initial v alues acc ording t o isen tropic r elations . Rememb er tha t the sta tic pr essur e value y ou en ter is r elative to the op erating pr essur e set in the Operating C onditions D ialog Box (p.3470 ). Note the c ommen ts in Pressur e Inputs and H ydrosta tic Head (p.921) regar ding h ydrosta tic pr essur e. 7.3.5.2.7. Defining the F low D irection You c an define the flo w dir ection a t a mass-flo w inlet e xplicitly , or y ou c an define the flo w to be normal t o the b oundar y. The pr ocedur e for defining the flo w dir ection is as f ollows, referring t o Figur e 7.34: The M ass-F low Inlet D ialog Box (p.936): 1.Specify the flo w dir ection b y selec ting Direction Vector or Normal t o Boundar y in the Direction Specific ation M etho d drop-do wn list. 2.If you selec ted Direction Vector and y our geometr y is 2D , go t o the ne xt step. If your geometr y is 3D , choose Cartesian (X, Y, Z),Cylindr ical (R adial, Tangen tial, Axial) ,Local C ylindr ical (R adial, Tangen- tial, Axial) , or Local C ylindr ical S wirl in the Coordina te System drop-do wn list. See Defining the F low Direction (p.923) for inf ormation ab out C artesian, cylindr ical, local cylindr ical, and lo cal cylindr ical swir l coordina te sy stems . 3.If you selec ted Direction Vector, set the v ector comp onen ts as f ollows: •If your geometr y is 2D non-axisymmetr ic, or y ou chose t o use a 3D Cartesian coordina te sy stem, enter appr opriate values f or the X-,Y-, and (in 3D) Z-Comp onen t of F low D irection . •If your geometr y is 2D axisymmetr ic, or y ou chose t o use a 3D Cylindr ical coordina te sy stem, enter appr opriate values f or the Axial- ,Radial- , and (if y ou ar e mo deling swir l or using c ylindr ical coordin- ates) Tangen tial-C omp onen t of F low D irection . •If you chose t o use a 3D Local C ylindr ical coordina te sy stem, enter appr opriate values f or the Axial- , Radial- , and Tangen tial-C omp onen t of F low D irection , and then sp ecify the X,Y, and Z comp onen ts of Axis Or igin and the Axis D irection . 939Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions•If you chose t o use a 3D Local C ylindr ical S wirl coordina te sy stem, enter appr opriate values f or the Axial- and Radial-C omp onen t of F low D irection in the axial and r adial planes , and the Tangen tial- Velocity. Specify the X,Y, and Z comp onen ts of the Axis Or igin and the Axis D irection . Imp ortant Local C ylindr ical S wirl should not b e used f or op en channel b oundar y conditions and on the mixing plane b oundar ies, while using the mixing plane mo del. 4.If you selec ted Normal t o Boundar y, ther e are no additional inputs f or flo w dir ection. Imp ortant Note tha t if y ou ar e mo deling axisymmetr ic swir l, the flo w dir ection will b e nor mal t o the b oundar y; tha t is, ther e will b e no swir l comp onen t at the b oundar y for axisym- metr ic swir l. 7.3.5.2.8. Defining Turbulenc e Paramet ers For turbulen t calcula tions , ther e ar e se veral w ays in which y ou c an define the turbulenc e par amet ers. Instr uctions f or deciding which metho d to use and det ermining appr opriate values f or these inputs are pr ovided in Determining Turbulenc e Paramet ers (p.914).Turbulenc e mo deling is descr ibed in Modeling Turbulenc e (p.1375 ). 7.3.5.2.9. Defining R adiation P aramet ers If you ar e using the P-1, DTRM, DO , sur face-to-sur face, or MC mo dels , you will set the Internal Emissivit y and (optionally) External Black B ody Temp erature. See Defining B oundar y Conditions for R adia tion (p.1514 ) for details . (The R osseland r adia tion mo del do es not r equir e an y boundar y condition inputs .) 7.3.5.2.10. Defining Sp ecies M ass or Mole F ractions If you ar e mo deling sp ecies tr ansp ort, you will set the sp ecies mass or mole fr actions under Species Mole F ractions or Species M ass F ractions . For details , see Defining C ell Z one and B oundar y Condi- tions f or S pecies (p.1649 ). 7.3.5.2.11. Defining N on-P remix ed C ombustion P aramet ers If you ar e using the non-pr emix ed or par tially pr emix ed c ombustion mo del, you will set the Mean Mixture Fraction and Mixture Fraction Varianc e (and the Secondar y M ean M ixture Fraction and Secondar y M ixture Fraction Varianc e, if y ou ar e using t wo mix ture fractions), as descr ibed in De- fining N on-P remix ed B oundar y Conditions (p.1739 ). 7.3.5.2.12. Defining P remix ed C ombustion B oundar y Conditions If you ar e using the pr emix ed or par tially pr emix ed c ombustion mo del, you will set the Progress Variable , as descr ibed in Setting B oundar y Conditions f or the P rogress Variable (p.1754 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 940Cell Z one and B oundar y Conditions7.3.5.2.13. Defining D iscr ete Phase B oundar y Conditions If you ar e mo deling a discr ete phase of par ticles , you c an set the fa te of par ticle tr ajec tories a t the mass-flo w inlet. See Setting B oundar y Conditions f or the D iscrete Phase (p.1985 ) for details . 7.3.5.2.14. Defining O pen C hannel B oundar y Conditions If you ar e using the VOF mo del f or multiphase flo w and mo deling op en channel flo ws, you will need to sp ecify the Free S urface Level,Bottom L evel, and additional par amet ers. See Modeling Op en Channel F lows (p.2144 ) for details . 7.3.5.3. Default S ettings at M ass-F low Inlet B oundaries Default settings (in SI) f or mass-flo w inlet b oundar y conditions ar e as f ollows: 1 Mass F low R ate 300 Total Temp erature 0 Supersonic/Initial G auge P ressur e 1 X-C omp onen t of F low D irection 0 Y-C omp onen t of F low D irection 0 Z-Comp onen t of F low D irection 5% Turbulen t In tensit y 10 Turbulen t Visc osit y Ratio 7.3.5.4. Calculation P rocedur e at M ass-F low Inlet B oundaries When mass flo w b oundar y conditions ar e used f or an inlet z one , a velocity is c omput ed f or each fac e in tha t zone , and this v elocity is used t o comput e the flux es of all r elevant solution v ariables in to the domain. With each it eration, the c omput ed v elocity is adjust ed so tha t the c orrect mass flo w value is main tained . To comput e this v elocity, your inputs f or mass flo w rate, flow dir ection, static pr essur e, and t otal temp erature ar e used . There ar e two ways to sp ecify the mass flo w rate.The first is t o sp ecify the t otal mass flo w rate, , for the inlet. The sec ond is t o sp ecify the mass flux, (mass flo w rate per unit ar ea). If a t otal mass flow rate is sp ecified , ANSY S Fluen t converts it in ternally t o a unif orm mass flux b y dividing the mass flow rate by the t otal inlet ar ea: (7.92) If the dir ect mass flux sp ecific ation option is used , the mass flux c an b e varied o ver the b oundar y by using pr ofile files or user-defined func tions . If the a verage mass flux is also sp ecified (either e xplicitly by you or aut oma tically b y ANSY S Fluen t), it is used t o correct the sp ecified mass flux pr ofile , as de- scribed ear lier in this sec tion. Onc e the v alue of at a giv en fac e has b een det ermined , the densit y, , at the fac e must b e de- termined in or der t o find the nor mal v elocity, .The manner in which the densit y is obtained dep ends upon whether the fluid is mo deled as an ideal gas or not. Each of these c ases is e xamined b elow. 941Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions7.3.5.4.1. Flow C alculations at M ass F low B oundaries for Ideal G ases If the fluid is an ideal gas , the sta tic t emp erature and sta tic pr essur e ar e requir ed t o comput e the densit y: (7.93) If the inlet is sup ersonic , the sta tic pr essur e used is the v alue tha t has b een set as a b oundar y con- dition. If the inlet is subsonic , the sta tic pr essur e is e xtrapolated fr om the c ells inside the inlet fac e. The sta tic t emp erature at the inlet is c omput ed fr om the t otal en thalp y, which is det ermined fr om the t otal t emp erature tha t has b een set as a b oundar y condition. The t otal en thalp y is giv en b y (7.94) wher e the v elocity magnitude is r elated t o the mass flo w rate giv en b y Equa tion 7.92 (p.941) and the k nown user-sp ecified flo w dir ection v ector. Using Equa tion 7.93 (p.942) to relate densit y to the (known) sta tic pr essur e and (unk nown) t emp erature,Equa tion 7.94 (p.942) can b e solv ed t o obtain the sta tic t emp erature. 7.3.5.4.2. Flow C alculations at M ass F low B oundaries for Inc ompr essible F lows When y ou ar e mo deling inc ompr essible flo ws, the sta tic t emp erature is equal t o the t otal t emp erature. The densit y at the inlet is either c onstan t or r eadily c omput ed as a func tion of the t emp erature and (optionally) the sp ecies mass or mole fr actions .The v elocity is then c omput ed using Equa- tion 7.92 (p.941). 7.3.5.4.3. Flux C alculations at M ass F low B oundaries To comput e the flux es of all v ariables a t the inlet , the flux v elocity, , is used along with the inlet value of the v ariable in question. For e xample , the flux of mass is , and the flux of turbulenc e kinetic ener gy is .These flux es ar e used as b oundar y conditions f or the c orresponding c onser- vation equa tions dur ing the c ourse of the solution. 7.3.6. Mass-F low Outlet B oundar y Conditions Mass-flo w outlet b oundar ies c an b e used in ANSY S Fluen t to pump flo w out of the domain a t a pr e- scribed mass flo w rate or mass flux distr ibution. A mass-flo w outlet is of ten used when it is mor e im- portant to ma tch a pr escr ibed mass flo w rate than t o ma tch the sta tic pr essur e of the outflo w str eam. 7.3.6.1. Limitations Mass-flo w outlet b oundar ies ha ve the f ollowing limita tions: •It is supp orted with single-phase flo w only , and so is not supp orted with the VOF, mix ture, and E uler ian multiphase mo dels in the pr essur e-based solv er. •It is not supp orted with the Wet Steam mo del in the densit y-based solv er. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 942Cell Z one and B oundar y Conditions7.3.6.2. Inputs at M ass-F low O utlet B oundaries 7.3.6.2.1. Summar y You will en ter the f ollowing inf ormation f or a mass-flo w outlet b oundar y: •mass flo w rate, mass flux, mass flux with a verage mass flux, or e xit c orrected mass flo w rate with r eference temp erature and gauge pr essur e •radia tion par amet ers (f or calcula tions using the P-1, DTRM, DO, surface-to-sur face, or MC mo dels) •discr ete phase b oundar y conditions (f or discr ete phase c alcula tions) All values ar e en tered in the Mass-F low Outlet D ialog Box (p.3507 ) (Figur e 7.35: The M ass-F low Outlet Dialog Box (p.943)), which is op ened fr om the Boundar y Conditions task page (as descr ibed in Setting C ell Z one and B oundar y Conditions (p.839)). Figur e 7.35: The M ass-F low Outlet D ialo g Box 7.3.6.2.2. Selec ting the R efer enc e Frame Mass-flo w outlets only supp ort the Rela tive to Adjac ent Cell Z one specific ation f or the Referenc e Frame . 7.3.6.2.3. Defining the M ass F low R ate or M ass F lux You c an sp ecify the mass flo w rate thr ough the outlet z one and ha ve ANSY S Fluen t convert this value t o mass flux, or sp ecify the mass flux dir ectly. For c ases wher e the mass flux v aries acr oss the boundar y, you c an sp ecify an a verage mass flux. For c ompr essible pr oblems , you c an sp ecify tha t the mass flo w rate is adjust ed t o total c onditions a t the outlet , thus main taining a c onstan t exit corrected mass flo w rate. 943Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y ConditionsYou c an define the mass flo w or mass flux r ate using a pr ofile or a user-defined func tion (UDF). For an e xample of a mass-flo w outlet UDF , see DEFINE_PROFILE in the Fluen t Customiza tion M anual . Imp ortant The ho oked UDF or tr ansien t profile c an only b e used t o pr ovide time-v arying sp ecific ation of mass flo w or mass flux r ate.Therefore, the tr ansien t solv er must b e used t o run the simula tion. Note tha t the v ariation of pr ofile with p osition in spac e is not applic able with this ho okup. The inputs f or mass flo w rate or flux ar e as f ollows: 1.Make a selec tion in the Mass F low S pecific ation M etho d drop-do wn list t o sp ecify whether y ou will define a Mass F low R ate,Mass F lux,Mass F lux with A verage M ass F lux, or (if the densit y of the ma- terial is defined either as an ideal gas or using a r eal gas mo del) Exit C orrected M ass F low R ate. 2.If you selec ted Mass F low R ate (the default), enter the pr escr ibed Mass F low R ate when constan t is selec ted fr om the dr op-do wn list. Other wise , selec t your ho oked user-defined func tion (UDF) or tr ansien t profile . 3.If you selec ted Mass F lux, enter the pr escr ibed Mass F lux (or selec t your ho oked UDF or pr ofile). 4.If you selec ted Mass F lux with A verage M ass F lux, enter the pr escr ibed Mass F lux (or selec t your hooked UDF or pr ofile) and Average M ass F lux. Note tha t if y ou sp ecify a mass flux pr ofile such tha t the a verage mass flux in tegrated o ver the zone ar ea is 4.7, but y ou ac tually w ant to ha ve a t otal mass flux of 5, you c an k eep the pr ofile unchanged , and sp ecify an a verage mass flux of 5. ANSY S Fluen t will main tain the pr ofile shap e but adjust the v alues so tha t the r esulting mass flux acr oss the b oundar y is 5. 5.If you selec ted Exit C orrected M ass F low R ate, enter the pr escr ibed Exit C orrected M ass F low R ate (or selec t your ho oked UDF or pr ofile); this c orresponds t o in Equa tion 7.96 (p.946).Then en ter the ECMF Ref erenc e Temp erature ( ) and the ECMF Ref erenc e Gauge P ressur e ( ). For complet e details ab out this metho d, see Exit C orrected M ass F low Rate (p.946). Imp ortant Note tha t for axisymmetr ic pr oblems: •If you pr ovide a mass flo w rate, you must sp ecify the flo w rate thr ough the en tire ( -radian) domain, not thr ough a 1-r adian slic e. •If you pr ovide a mass flux r ate, you must sp ecify the flux thr ough a 1-r adian slic e of the domain. The mass flo w b oundar y will b e pumping flo w out of the domain nor mal t o the b oundar y at the prescr ibed r ate or flux. If the mass flo w rate is sp ecified , then b y default , the flux es on the b oundar y Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 944Cell Z one and B oundar y Conditionswill b e allo wed t o vary to pr eser ve the flo w pr ofile out of the domain. At convergenc e, the t otal mass flo w rate should ma tch the sp ecified v alue . Imp ortant Note tha t if c onstan t mass flux is needed r ather than the default v ariable flux es to pr eser ve the pr ofiles , then y ou c an do so via the t ext command define/boundary-condi- tions/bc-settings/mass-flow . Answ er no when ask ed t o preserve profile while flow leaves . Note The mass-flo w outlet b oundar y condition is designed t o be str ictly used only when flo w is lea ving the domain; it should not b e used f or mix ed flo w conditions (wher e flo w is flowing in and out) or when flo w is changing dir ections . 7.3.6.2.4. Defining R adiation P aramet ers If you ar e using the P-1, DTRM, DO , sur face-to-sur face, or MC mo dels , you will set the Internal Emissivit y and (optionally) External Black B ody Temp erature. See Defining B oundar y Conditions for R adia tion (p.1514 ) for details . (The R osseland r adia tion mo del do es not r equir e an y boundar y condition inputs .) 7.3.6.2.5. Defining D iscr ete Phase B oundar y Conditions If you ar e mo deling a discr ete phase of par ticles , you c an set the fa te of par ticle tr ajec tories a t the mass-flo w outlet. See Setting B oundar y Conditions f or the D iscrete Phase (p.1985 ) for details . 7.3.6.3. Default S ettings at M ass-F low O utlet B oundaries Default settings (in SI) f or mass-flo w outlet b oundar y conditions ar e as f ollows: 1 Mass F low R ate 7.3.6.4. Calculation P rocedur e at M ass-F low O utlet B oundaries For the Mass F low R ate specific ation metho d, you sp ecify the t otal mass flo w rate, , for the outlet. For the Mass F lux or Mass F lux with A veraged M ass F lux specific ation metho ds, you sp ecify the mass flux, (mass flo w rate per unit ar ea). If a t otal mass flo w rate is sp ecified , ANSY S Fluen t converts it in ternally t o a unif orm mass flux b y dividing the mass flo w rate by the t otal outlet ar ea: (7.95) If the dir ect mass flux sp ecific ation option is used , the mass flux c an b e varied o ver the b oundar y by using pr ofile files or user-defined func tions . If the a verage mass flux is also sp ecified , it is used t o correct the sp ecified mass flux pr ofile , as descr ibed pr eviously in this sec tion. Onc e the v alue of at a giv en fac e has b een det ermined , the densit y, , at the fac e must b e de- termined in or der t o find the nor mal v elocity, . 945Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y ConditionsBoundar y velocities ar e sc aled t o achie ve the sp ecified v alue of mass flo w rate or mass flux. When the mass-flo w outlet is used with the pr ofile pr eser ving f eature, a sc aling fac tor of the sp ecified mass flow rate over the c omput ed mass flo w rate at the b oundar y is used t o sc ale the nor mal fac e velocities at the b oundar y.The other v elocity comp onen ts will b e extrapolated fr om the in terior. Flow variables such as pr essur e, temp erature, species , or other sc alar quan tities will b e also e xtrapolated fr om adjac ent cell c enters. 7.3.6.4.1. Exit C orrected M ass F low R ate The Exit C orrected M ass F low R ate specific ation metho d adjusts the mass flo w rate to the t otal conditions a t the outlet , main taining a c onstan t exit c orrected mass flo w rate.This b oundar y option is mainly in tended f or turb omachiner y applic ations .This metho d allo ws you t o sw eep thr ough the complet e machine op erational r ange , including machine op erating p oints fr om chok ed flo w to stall conditions .When using the Exit C orrected M ass F low R ate specific ation metho d, the b oundar y operates lik e a mass-flo w outlet on the lef t side of the sp eedline cur ve away from the b est efficienc y point, and mor e lik e a pr essur e outlet b oundar y to the r ight of the b est efficienc y point all the w ay beyond the chok e point.This metho d allo ws you t o sp ecify the equiv alen t mass flo w, based on similar cr iteria, corrected t o a sp ecified r eference temp erature and pr essur e. For c ompr essible flo ws, the e xit c orrected mass flo w rate ( ) is c alcula ted as: (7.96) wher e and are mass-a veraged v alues of t otal pr essur e and t emp erature in the absolut e frame at the outlet. and are the r eference conditions , which ar e constan ts in the equa tion. It should b e not ed tha t the numer ical b ehavior of the b oundar y condition is not aff ected b y the choic e of reference conditions; rather , the r eference conditions simply pr ovide a dimensional meaning t o the other wise non-dimensional mass flo w rate. It is t ypic al to sp ecify these r eference conditions t o be the same as the inflo w total pr essur e and t emp erature. In or der t o main tain a c onstan t exit c orrected mass flo w, you c an obser ve tha t the r esulting mass flow rate must b e pr oportional t o the e xit t otal pr essur e and in versely pr oportional t o the squar e root of the e xit t otal t emp erature (or equiv alen tly, inversely pr oportional t o the stagna tion sp eed of sound). This allo ws the b oundar y condition t o adapt d ynamic ally t o varying op erating c onditions , while r emaining stable as the flo w de velops fr om the initial guess . Note tha t the Exit C orrected M ass F low R ate specific ation metho d is only a vailable f or ideal gas and r eal gas ma terials. You c an obtain an initial e xit c orrected mass flo w rate value ( ) from a pr eviously c onverged c ase that uses standar d inlet and outlet b oundar ies (f or e xample , a pr essur e inlet and a pr essur e outlet). Use the c onverged solution t o obtain the mass-flo w-averaged v alue of and at the outlet boundar y, as w ell as the mass flo w rate ( ).These v alues c an then b e applied t o Equa tion 7.96 (p.946) along with and (which ar e usually tak en as the inflo w total t emp erature and pr essur e). After y ou ha ve calcula ted the e xit c orrected mass flo w rate, you c an adjust this v alue up or do wn in or der t o traverse the sp eed line fr om chok e to stall. 7.3.7. Inlet Vent Boundar y Conditions Inlet v ent boundar y conditions ar e used t o mo del an inlet v ent with a sp ecified loss c oefficien t, flow direction, and ambien t (inlet) pr essur e and t emp erature. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 946Cell Z one and B oundar y Conditions7.3.7.1. Inputs at Inlet Vent B oundaries You will en ter the f ollowing inf ormation f or an inlet v ent boundar y: •type of r eference frame •total (stagna tion) pr essur e •total (stagna tion) t emp erature •flow dir ection •static pr essur e •turbulenc e par amet ers (f or turbulen t calcula tions) •radia tion par amet ers (f or calcula tions using the P-1, DTRM, DO, surface-to-sur face, or MC mo dels) •chemic al sp ecies mass or mole fr actions (f or sp ecies c alcula tions) •mixture fraction and v arianc e (for non-pr emix ed or par tially pr emix ed c ombustion c alcula tions) •progress v ariable (f or pr emix ed or par tially pr emix ed c ombustion c alcula tions) •discr ete phase b oundar y conditions (f or discr ete phase c alcula tions) •multiphase b oundar y conditions (f or gener al multiphase c alcula tions) •loss c oefficien t •open channel flo w par amet ers (f or op en channel flo w calcula tions using the VOF multiphase mo del) All values ar e en tered in the Inlet Vent Dialog Box (p.3490 ) (Figur e 7.36: The Inlet Vent Dialog Box (p.948)), which is op ened fr om the Boundar y Conditions task page (as descr ibed in Setting C ell Z one and Boundar y Conditions (p.839)). The first 12 it ems list ed ab ove ar e sp ecified in the same w ay tha t the y are sp ecified a t pressur e inlet boundar ies. See Inputs a t Pressur e Inlet B oundar ies (p.920) for details . Specific ation of the loss c oeffi- cien t is descr ibed her e. Open channel b oundar y condition inputs ar e descr ibed in Modeling Op en Channel F lows (p.2144 ). 947Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y ConditionsFigur e 7.36: The Inlet Vent Dialo g Box 7.3.7.1.1. Specifying the L oss C oefficient An inlet v ent is c onsider ed t o be infinit ely thin, and the pr essur e dr op thr ough the v ent is assumed to be pr oportional t o the d ynamic head of the fluid , with an empir ically det ermined loss c oefficien t that you supply .That is, the pr essur e dr op, , varies with the nor mal c omp onen t of v elocity thr ough the v ent, , as f ollows: (7.97) wher e is the fluid densit y, and is the non-dimensional loss c oefficien t. Imp ortant is the pr essur e dr op in the dir ection of the flo w; ther efore the v ent will app ear as a resistanc e even in the c ase of backflo w. You c an define the Loss-C oefficien t across the v ent as a constan t,polynomial ,piec ewise-linear , or piec ewise-p olynomial func tion of the nor mal v elocity.The dialo g boxes for defining these func tions ar e the same as those used f or defining t emp erature-dep enden t properties. See Defining Properties U sing Temp erature-Dependen t Functions (p.1095 ) for details . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 948Cell Z one and B oundar y Conditions7.3.8. Intake Fan B oundar y Conditions Intake fan b oundar y conditions ar e used t o mo del an e xternal in take fan with a sp ecified pr essur e jump , flow dir ection, and ambien t (in take) pr essur e and t emp erature. Note The in take fan b oundar y condition c onsiders only momen tum. Diffusion pr ocesses ar e not consider ed. 7.3.8.1. Inputs at Intak e Fan B oundaries You will en ter the f ollowing inf ormation f or an in take fan b oundar y: •type of r eference frame •total (stagna tion) pr essur e •total (stagna tion) t emp erature •flow dir ection •static pr essur e •turbulenc e par amet ers (f or turbulen t calcula tions) •radia tion par amet ers (f or calcula tions using the P-1, DTRM, DO, surface-to-sur face, or MC mo dels) •chemic al sp ecies mass or mole fr actions (f or sp ecies c alcula tions) •mixture fraction and v arianc e (for non-pr emix ed or par tially pr emix ed c ombustion c alcula tions) •progress v ariable (f or pr emix ed or par tially pr emix ed c ombustion c alcula tions) •discr ete phase b oundar y conditions (f or discr ete phase c alcula tions) •multiphase b oundar y conditions (f or gener al multiphase c alcula tions) •pressur e jump •open channel flo w par amet ers (f or op en channel flo w calcula tions using the VOF multiphase mo del) All values ar e en tered in the Intake Fan D ialog Box (p.3496 ) (sho wn in Figur e 7.37: The In take Fan D ialog Box (p.950)), which is op ened fr om the Boundar y Conditions task page (as descr ibed in Setting C ell Zone and B oundar y Conditions (p.839)). The first 12 it ems list ed ab ove ar e sp ecified in the same w ay tha t the y are sp ecified a t pressur e inlet boundar ies. See Inputs a t Pressur e Inlet B oundar ies (p.920) for details . Specific ation of the pr essur e jump is descr ibed her e. Open channel b oundar y condition inputs ar e descr ibed in Modeling Op en Channel F lows (p.2144 ). 949Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y ConditionsFigur e 7.37: The In take Fan D ialo g Box 7.3.8.1.1. Specifying the P ressur e Jump An in take fan is c onsider ed t o be infinit ely thin, and the disc ontinuous pr essur e rise acr oss it is specified as a func tion of the v elocity thr ough the fan. In the c ase of r eversed flo w, the fan is tr eated like an outlet v ent with a loss c oefficien t of unit y. You c an define the Pressur e-Jump across the fan as a constan t,polynomial ,piec ewise-linear , or piec ewise-p olynomial func tion of the nor mal v elocity.The dialo g boxes for defining these func tions are the same as those used f or defining t emp erature-dep enden t properties. See Defining P roperties Using Temp erature-Dependen t Functions (p.1095 ) for details . 7.3.9. Pressur e Outlet B oundar y Conditions Pressur e outlet b oundar y conditions r equir e the sp ecific ation of a sta tic (gauge) pr essur e at the outlet boundar y.The v alue of the sp ecified sta tic pr essur e is used only while the flo w is subsonic . Should the flo w b ecome lo cally sup ersonic , the sp ecified pr essur e will no longer b e used; pressur e will b e extrapolated fr om the flo w in the in terior. All other flo w quan tities ar e extrapolated fr om the in terior. A set of “backflo w” conditions is also sp ecified should the flo w reverse dir ection a t the pr essur e outlet boundar y dur ing the solution pr ocess. Convergenc e difficulties will b e minimiz ed if y ou sp ecify r ealistic values f or the backflo w quan tities . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 950Cell Z one and B oundar y ConditionsSeveral options in ANSY S Fluen t exist, wher e a r adial equilibr ium outlet b oundar y condition c an b e used (see Defining S tatic P ressur e (p.952) and a tar get mass flo w rate for pr essur e outlets (see Target Mass F low R ate Option (p.958) for details) c an b e sp ecified . For an o verview of flo w b oundar ies, see Flow Inlet and Exit B oundar y Conditions (p.913). 7.3.9.1. Inputs at P ressur e O utlet B oundaries 7.3.9.1.1. Summar y You will en ter or selec t the f ollowing inf ormation f or a pr essur e outlet b oundar y: •static pr essur e •pressur e pr ofile multiplier •backflo w conditions –total (stagna tion) t emp erature (for ener gy calcula tions) –backflo w pr essur e sp ecific ation –backflo w dir ection sp ecific ation metho d –turbulenc e par amet ers (f or turbulen t calcula tions) –chemic al sp ecies mass or mole fr actions (f or sp ecies c alcula tions) –mixture fraction and v arianc e (for non-pr emix ed or par tially pr emix ed c ombustion c alcula tions) –progress v ariable (f or pr emix ed or par tially pr emix ed c ombustion c alcula tions) –multiphase b oundar y conditions (f or gener al multiphase c alcula tions) –type of backflo w reference frame (not a vailable f or multiphase flo ws or with the ac oustic w ave mo del) •radia tion par amet ers (f or calcula tions using the P-1, DTRM, DO, surface-to-sur face, or MC mo dels) •discr ete phase b oundar y conditions (f or discr ete phase c alcula tions) •open channel flo w par amet ers (f or op en channel flo w calcula tions using the VOF multiphase mo del) •radial equilibr ium pr essur e distr ibution •average pr essur e sp ecific ation (not a vailable f or multiphase flo ws) •target mass flo w rate (not a vailable f or multiphase flo ws) •acoustic w ave mo del settings All values ar e en tered in the Pressur e Outlet D ialog Box (p.3530 ) (Figur e 7.38: The P ressur e Outlet Dialog Box (p.952)), which is op ened fr om the Boundar y Conditions task page (as descr ibed in Setting C ell Z one and B oundar y Conditions (p.839)). Note tha t op en channel b oundar y condition inputs ar e descr ibed in Modeling Op en C hannel F lows (p.2144 ), and ac oustic w ave mo del settings are descr ibed in Boundar y Acoustic Wave M odels (p.1021 ). 951Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y ConditionsFigur e 7.38: The P ressur e Outlet D ialo g Box 7.3.9.1.2. Defining Static P ressur e To set the sta tic pr essur e at the pr essur e outlet b oundar y, enter the appr opriate value f or Gauge Pressur e in the Pressur e Outlet dialo g box.This v alue will b e used when the flo w is lo cally subsonic . Should the flo w b ecome lo cally sup ersonic , the pr essur e will b e extrapolated fr om the upstr eam conditions . By default the subsonic and sup ersonic lo cal flo w condition a t the b oundar y is det ermined based on the lo cal nor mal v elocity comp onen t. Rememb er tha t the sta tic pr essur e value y ou en ter is r elative to the op erating pr essur e set in the Operating C onditions D ialog Box (p.3470 ). Refer to Pressur e Inputs and H ydrosta tic H ead (p.921) re- garding h ydrosta tic pr essur e. ANSY S Fluen t also pr ovides an option t o use a r adial equilibr ium outlet b oundar y condition. This option is used t o mo del the e xit flo w in turb omachiner y flo w pr oblems .To tur n on this option, enable Radial E quilibr ium P ressur e D istribution .When this f eature is ac tive, the sp ecified gauge pr essur e applies only t o the p osition of minimum r adius (r elative to the axis of r otation) a t the b oundar y.The static pr essur e on the r est of the z one is c alcula ted fr om the assumption tha t radial v elocity is neg- ligible , so tha t the pr essur e gr adien t is giv en b y Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 952Cell Z one and B oundar y Conditions(7.98) wher e is the distanc e from the axis of r otation and is the tangen tial v elocity. Note tha t this boundar y condition c an b e used e ven if the r otational v elocity is z ero. For e xample , it c ould b e applied to the c alcula tion of the flo w thr ough an annulus c ontaining guide v anes . Imp ortant Note tha t the r adial equilibr ium outlet c ondition is a vailable only f or 3D and axisymmetr ic swir l calcula tions . ANSY S Fluen t also pr ovides an option t o use an Average P ressur e Specific ation metho d at the pressur e outlet b oundar y.This option allo ws the pr essur e along the outlet b oundar y to vary, but main tain an a verage equiv alen t to the sp ecified v alue in the Gauge P ressur e input field .The pr essur e variation allo wed in this b oundar y implemen tation sligh tly diminishes the r eflec tivit y of the b oundar y as c ompar ed with the default unif orm pr essur e sp ecific ation. In the densit y-based solv er two averaging metho ds ar e available ,Strong A veraging and Weak A veraging .The a verage pr essur e sp ecific ation in the pr essur e-based solv er is the same as the str ong pr essur e averaging in the densit y-based solv er. For mor e details , see Calcula tion P rocedur e at Pressur e Outlet B oundar ies (p.955). The Pressur e Profile M ultiplier allo ws you t o sp ecify a c onstan t fac tor b y which the Gauge P ressur e is multiplied .This is pr ovided mainly f or c ases wher e a non-unif orm distr ibution of the sta tic pr essur e at the pr essur e outlet b oundar y is sp ecified b y means of a pr ofile file or a user-defined func tion. The scaling of an outlet pr ofile with a multiplier c an b e convenien t, for e xample , when c omputing a performanc e map f or a turb omachine a t diff erent mass flo w rates.The option will also w ork for a constan t Gauge P ressur e simply b y sc aling its v alue b y a fac tor.This sc aled pr essur e value will b e used c onsist ently when additional options ar e enabled in the Pressur e Outlet dialo g box; for e xample , when the Radial E quilibr ium P ressur e D istribution option is enabled , the sc aled gauge pr essur e will b e applied t o the p osition of minimum r adius (r elative to the axis of r otation) a t the b oundar y. 7.3.9.1.3. Defining B ackflo w C onditions Backflo w pr operties c onsist ent with the mo dels y ou ar e using will app ear in the Pressur e Outlet dialo g box.The sp ecified v alues will b e used only if flo w is pulled in thr ough the outlet. •The Backflo w Total Temp erature (in the Thermal tab) should b e set f or pr oblems in volving ener gy calcula tion. •When the dir ection of the backflo w re-en tering the c omputa tional domain is k nown, and deemed t o be relevant to the flo w field solution, you c an sp ecify it cho osing one of the options a vailable in the Backflo w Direction S pecific ation M etho d drop-do wn list. The default v alue f or this field is Normal t o Boundar y, and r equir es no fur ther input. If you cho ose Direction Vector, the dialo g box will e xpand t o sho w the inputs f or the c omp onen ts of the dir ection v ector for the backflo w, and if y ou ar e running the 3D v ersion of ANSY S Fluen t, the dialo g box will displa y a Coordina te System drop-do wn list. If you cho ose From Neighb oring C ell, ANSY S Fluen t will det ermine the dir ection of the backflo w using the dir ection of the flow in the c ell la yer adjac ent to the pr essur e outlet. •For turbulen t calcula tions , ther e are se veral w ays in which y ou c an define the turbulenc e par amet ers. Instr uctions f or deciding which metho d to use in det ermining appr opriate values f or these inputs ar e provided in Determining Turbulenc e Paramet ers (p.914).Turbulenc e mo deling in gener al is descr ibed in Modeling Turbulenc e (p.1375 ). 953Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions•If you ar e mo deling sp ecies tr ansp ort, you will set the backflo w sp ecies mass or mole fr actions under Species M ass F ractions or Species M ole F ractions . For details , see Defining C ell Z one and B oundar y Conditions f or S pecies (p.1649 ). •If you ar e mo deling c ombustion using the non-pr emix ed or par tially pr emix ed c ombustion mo del, you will set the backflo w mix ture fraction and v arianc e values . See Defining N on-P remix ed B oundar y Condi- tions (p.1739 ) for details . •If you ar e mo deling c ombustion using the pr emix ed or par tially pr emix ed c ombustion mo del, you will set the backflo w Progress Variable value . See Setting B oundar y Conditions f or the P rogress Vari- able (p.1754 ) for details . •If you ar e using the VOF, mix ture, or E uler ian mo del f or multiphase flo w, you will need t o sp ecify v olume fractions f or sec ondar y phases and (f or some mo dels) additional par amet ers. See Defining M ultiphase Cell Z one and B oundar y Conditions (p.2124 ) for details . •If backflo w occurs , 1. The pr essur e you sp ecified as the Gauge P ressur e will b e used t o det ermine the t otal pr essur e or the sta tic pr essur e (based on y our selec tion fr om the Backflo w P ressur e Specific ation drop-do wn list), so y ou need not sp ecify a backflo w pr essur e value e xplicitly .When Total P ressur e is selec ted for Backflo w P ressur e Specific ation , boundar y fac e pr essur e values ar e calcula ted b y combining the Gauge P ressur e with a d ynamic c ontribution tha t is based on the v elocity in the adjac ent cell zone; when Static P ressur e is selec ted f or Backflo w P ressur e Specific ation , the sp ecified Gauge Pressur e value is dir ectly imp osed as the b oundar y fac e pr essur e. 2. The flo w dir ection will b e based on y our selec tion fr om the Backflo w D irection S pecific ation Metho d drop-do wn list. 3. The t otal t emp erature, total pr essur e, and flo w dir ections ar e in absolut e or relativ e to the adjac ent cell z one reference frames , based on the Backflo w Ref erenc e Frame setting sp ecified in the Pressur e Outlet dialo g box. If the c ell z one adjac ent to the pr essur e outlet is mo ving (tha t is, if y ou ar e using a mo ving r eference frame , multiple r eference frames , mixing planes , or sliding meshes) and y ou ar e using the pr essur e- based solv er, the v elocity in the d ynamic c ontribution t o total pr essur e (see Equa tion 7.82 (p.922)) will b e absolut e or r elative to the motion of the c ell z one , dep ending on whether or not the Ab- solut e velocity formula tion is selec ted in the Gener al task page . For the densit y-based solv er, the velocity in Equa tion 7.82 (p.922) (or the M ach numb er in Equa tion 7.83 (p.922)) is alw ays in the absolut e frame . Imp ortant Even if no backflo w is e xpected in the c onverged solution, you should alw ays set r ealistic values t o minimiz e convergenc e difficulties in the e vent tha t backflo w do es o ccur dur ing the c alcula tion. The Backflo w Ref erenc e Frame option is not a vailable f or all multiphase mo dels or non- reflec ting b oundar y condition options . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 954Cell Z one and B oundar y Conditions7.3.9.1.3.1. Prevent R everse F low When this option is selec ted, Fluen t will er ect artificial w alls on the b oundar y mesh fac es to pr event flow back in to the domain. The ar tificial w alls ar e remo ved when the flo w is no longer en tering the domain and when a fa vorable pr essur e gr adien t is r ecovered a t the b oundar y mesh fac es. When ar tificial w alls ar e created, Fluen t will pr int a message in the c onsole windo w indic ating the numb er of fac es on which ar tificial w alls ha ve been er ected and the equiv alen t area p ercentage of the b oundar y it r epresen ts. Note This f eature is not a vailable with multiphase flo w. 7.3.9.1.4. Defining R adiation P aramet ers If you ar e using the P-1, DTRM, DO , sur face-to-sur face, or MC mo dels , you will set the Internal Emissivit y and (optional) External Black B ody Temp erature M etho d. See Defining B oundar y Conditions f or R adia tion (p.1514 ) for details . (The R osseland r adia tion mo del do es not r equir e an y boundar y condition inputs .) 7.3.9.1.5. Defining D iscr ete Phase B oundar y Conditions If you ar e mo deling a discr ete phase of par ticles , you c an set the fa te of par ticle tr ajec tories a t the pressur e outlet. See Setting B oundar y Conditions f or the D iscrete Phase (p.1985 ) for details . 7.3.9.1.6. Defining O pen C hannel B oundar y Conditions If you ar e using the VOF mo del f or multiphase flo w and mo deling op en channel flo ws, you will need to sp ecify the Free S urface Level,Bottom L evel, and additional par amet ers. See Modeling Op en Channel F lows (p.2144 ) for details . 7.3.9.2. Default S ettings at P ressur e O utlet B oundaries Default settings (in SI) f or pr essur e outlet b oundar y conditions ar e as f ollows: 0 Gauge P ressur e 1 Pressur e Profile M ultiplier 300 Backflo w Total Temp erature 5% Backflo w Turbulen t In tensit y 10 Backflo w Turbulen t Visc osit y Ratio 7.3.9.3. Calculation P rocedur e at P ressur e O utlet B oundaries At pressur e outlets , if the flo w exiting the b oundar y is subsonic , then ANSY S Fluen t uses the pr essur e specified in the Pressur e Outlet dialo g box as the sta tic pr essur e of the fluid a t the outlet plane , , and e xtrapolates all other c onditions fr om the in terior of the domain. However, if the flo w exiting the b oundar y becomes sup ersonic , then the fac e pr essur e values ar e extrapolated fr om the in terior cell pr essur e. 955Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions7.3.9.3.1. Average P ressur e Sp ecific ation When this option is selec ted, the e xit pr essur e is not k ept c onstan t over the pr essur e outlet b oundar y, but inst ead is allo wed t o vary acr oss the b oundar y while main taining an a verage b oundar y pr essur e close t o the sp ecified sta tic e xit pr essur e.This option c an b e used f or pr essur e sp ecified as a c onstan t or as a pr ofile (f or e xample , in turb omachiner y cases with r adial, axial, or r adial equilibr ium pr essur e distr ibutions). There ar e two implemen tations of the Average P ressur e Specific ation .These ar e Strong A veraging and Weak A veraging .The str ong a veraging appr oach is a vailable in b oth the densit y-based and the pr essur e-based solv er.The w eak a veraging appr oach is a vailable only in the densit y-based solv er. Note •The Average P ressur e Specific ation option is not a vailable with multiphase flo ws. •When using the densit y-based solv er,Strong A veraging is the r ecommended metho d and is used b y default. The w eak a veraging metho d is main tained pr imar ily for legac y cases . •When one of the Acoustic Wave M odels is ac tive, the A verage P ressur e Specific ation option is not off ered b ecause the pr essur e will b e obtained based on the Acoustic Wave M odel chosen. •Using the A verage P ressur e Specific ation option in unst eady simula tions c an r esult in non- physical pr essur e feedback and is not r ecommended . 7.3.9.3.1.1. Str ong A veraging In the Strong A veraging appr oach, the fac e pr essur e value for subsonic e xit flo w is c omput ed using the f ollowing e xpression: (7.99) = in terior c ell pr essur e at neighb oring e xit fac e, f wher e = a veraged in terior c ell pr essur e at a b oundar y = sp ecified e xit pr essur e = pr essur e blending fac tor; recovers the fully a veraged pr essur e, recovers the sp ecified pr essur e. When the str ong a veraging option is used with a pr ofile sp ecific ation metho d (radial, axial, or r adial equilibr ium pr essur e distr ibution) then the outlet b oundar y will b e sub divided in to radial or axial containers c alled “bins ”, and the ab ove averaging pr ocedur e is applied t o each bin. You c an use the f ollowing TUI c ommand t o change the blending fac tor and the numb er of bins: /define/boundary-conditions/bc-settings/pressure-outlet Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 956Cell Z one and B oundar y Conditions7.3.9.3.1.2. Weak A veraging When the w eak a veraging metho d is used and the flo w is subsonic , the pr essur e at the fac es of the outlet b oundar y is c omput ed using a w eigh ted a verage of the lef t and r ight sta te of the fac e boundar y.This w eigh ting is a blend of fif th-or der p olynomials based on the e xit fac e nor mal M ach numb er [69] (p.4008 ).Therefore, the fac e pr essur e is a func tion of ( , , ), wher e is the interior c ell pr essur e neighb oring the e xit fac e f, is the sp ecified e xit pr essur e, and is the fac e normal M ach numb er. Figur e 7.39: Pressur es a t the F ace of a P ressur e Outlet B oundar y For inc ompr essible flo ws, the fac e pr essur e is c omput ed as an a verage b etween the sp ecified pr essur e and the in terior pr essur e. (7.100) In this b oundar y implemen tation, the e xit pr essur e is not c onstan t along the pr essur e outlet boundar y. However, upon flo w convergenc e, the a verage b oundar y pr essur e will b e close t o the specified sta tic e xit pr essur e. 7.3.9.4. Other O ptional Inputs at P ressur e O utlet B oundaries 7.3.9.4.1. Non-R eflec ting B oundar y Conditions O ption One of the options tha t ma y be used a t pressur e outlets is non-r eflec ting b oundar y conditions (NRBC). This option is used when w aves ar e made t o pass thr ough the b oundar ies while a voiding false r e- flections . Details of non-r eflec ting b oundar y conditions c an b e found in Gener al N on-R eflec ting Boundar y Conditions (p.1031 ). 957Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions7.3.9.4.2. Target M ass F low R ate O ption The simple B ernoulli's equa tion is used t o adjust the pr essur e at every iteration on a pr essur e outlet zone in or der t o meet the desir ed mass flo w rate.The change in pr essur e, based on B ernoulli ’s equa tion is giv en b y the f ollowing equa tion: (7.101) wher e is the change in pr essur e, is the cur rent comput ed mass flo w rate at the pr essur e-outlet boundar y, is the r equir ed mass flo w rate, is the c omput ed a verage densit y at the pr essur e- outlet b oundar y, and is the ar ea of the pr essur e-outlet b oundar y. Limitations •The tar get mass flo w rate option is not a vailable with multiphase flo ws or when an y of the non-r eflec ting boundar y conditions mo dels ar e used . •If the pr essur e-outlet z one is used in the mixing-plane mo del, the tar get mass flo w rate option will not be available f or tha t par ticular z one . •The pr essur e outlet will not achie ve the tar get mass flo w rate if the flo w becomes chok ed (tha t is, the Mach numb er of the fluid in the pr essur e-outlet z one b ecomes equal t o 1). •The pr essur e outlet ma y not achie ve the tar get mass flo w rate if p orous z ones ar e pr esen t in the flo w domain c ausing a lar ge pr essur e dr op. Target M ass F low R ate Settings To use the tar get mass flo w rate option 1.Enable Target M ass F low R ate in the Pressur e Outlet dialo g box. 2.Specify the Target M ass F low as either a c onstan t value or ho ok a UDF t o set the tar get mass flo w rate. The settings f or the tar get mass flo w rate option c an b e acc essed fr om the target-mass- flow-rate-settings text command: define → boundary-conditions → target-mass-flow-rate-settings You will b e pr ompt ed t o a.Set the under-r elaxa tion fac tor (the default setting is 0.05). b.Enable the tar geted mass flo w rate verbosity (the default is no). If enabled , it pr ints to the c onsole windo w the r equir ed mass flo w rate, comput ed mass flo w rate, mean pr essur e, the new pr essur e imp osed on the outlet , and the change in pr essur e in SI units . 3.In the Pressur e Outlet dialo g box, specify the Upper Limit of A bsolut e Pressur e and Lower Limit of Absolut e Pressur e. Specifying the r ange of the pr essur e limits impr oves c onvergenc e in c ases with a large numb er of outlet b oundar ies, which ha ve diff erent pressur e variations on diff erent boundar ies. You c an also use the define/boundary-conditions/pressure-outlet text command t o specify these limits . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 958Cell Z one and B oundar y ConditionsFigur e 7.40: The P ressur e Outlet D ialo g Box with the Target M ass F low R ate Option E nabled Solution Str ategies When Using the Target M ass F low R ate O ption If convergenc e difficulties ar e enc oun tered or if the solution is not c onverging a t the desir ed mass flow rate, then tr y to lo wer the under-r elaxa tion fac tor fr om the default v alue . Other wise , you c an use the alt ernate metho d to converge a t the r equir ed mass flo w rate. In some c ases , you ma y want to swit ch off the tar get mass flo w rate option initially , then guess an exit pr essur e tha t will br ing the solution closer t o the tar get mass flo w rate. After the solution stabil- izes, you c an tur n on the tar get mass flo w rate option and it erate to convergenc e. For man y comple x flow pr oblems , this str ategy is usually v ery succ essful. The use of F ull M ultigr id Initializa tion is also v ery helpful in obtaining a go od star ting solution and in gener al will r educ e the time r equir ed t o get a c onverged solution on a tar get mass flo w rate. For further inf ormation on F ull M ultigr id Initializa tion, see Full M ultigr id (FMG) Initializa tion (p.2609 ). 959Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y ConditionsSetting Target M ass F low R ates Using UDFs For some unst eady pr oblems it is desir able tha t the tar get mass flo w rate be a func tion of the physical flo w time .This enf orcemen t of b oundar y condition c an b e done b y attaching a UDF with DEFINE_PROFILE func tions t o the tar get mass flo w rate field . Imp ortant Note tha t the mass flo w rate pr ofile is a func tion of time and only one c onstan t value should b e applied t o all z one fac es a t a giv en time . An example of a simple UDF using a DEFINE_PROFILE tha t will adjust the mass flo w rate can b e found in DEFINE_PROFILE in the Fluen t Customiza tion M anual . 7.3.10. Pressur e Far-F ield B oundar y Conditions Pressur e far-field c onditions ar e used in ANSY S Fluen t to mo del a fr ee-str eam c ondition a t infinit y, with free-str eam M ach numb er and sta tic c onditions b eing sp ecified .The pr essur e far-field b oundar y con- dition is of ten c alled a char acteristic b oundar y condition, sinc e it uses char acteristic inf ormation (Riemann in variants) t o det ermine the flo w variables a t the b oundar ies. 7.3.10.1. Limitations Note the f ollowing limita tions and r estrictions when using pr essur e far-field b oundar y conditions: •This b oundar y condition is applic able only when the densit y is c alcula ted using the ideal-gas la w (see Densit y (p.1099 )). Using it f or other flo ws is not p ermitt ed.To eff ectively appr oxima te true infinit e-extent conditions , you must plac e the far-field b oundar y far enough fr om the objec t of in terest. For e xample , in lifting air foil c alcula tions , it is not unc ommon f or the far-field b oundar y to be a cir cle with a r adius of 20 chor d lengths . •It is inc ompa tible with the multiphase mo dels ( VOF, mix ture, and E uler ian) tha t are available with the pressur e-based solv er. •It cannot b e applied t o flo ws tha t emplo y constan t densit y, the r eal gas mo del, and the w et st eam mo del, which ar e available in the densit y-based solv er. For an o verview of flo w b oundar ies, see Flow Inlet and Exit B oundar y Conditions (p.913). 7.3.10.2. Inputs at P ressur e Far-Field B oundaries 7.3.10.2.1. Summar y You will en ter the f ollowing inf ormation f or a pr essur e far-field b oundar y: •static pr essur e •Mach numb er •temp erature •flow dir ection Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 960Cell Z one and B oundar y Conditions•turbulenc e par amet ers (f or turbulen t calcula tions) •radia tion par amet ers (f or calcula tions using the P-1, DTRM, DO, surface-to-sur face, or MC mo dels) •chemic al sp ecies mass or mole fr actions (f or sp ecies c alcula tions) •discr ete phase b oundar y conditions (f or discr ete phase c alcula tions) All values ar e en tered in the Pressur e Far-F ield D ialog Box (p.3520 ) (Figur e 7.41: The P ressur e Far-F ield Dialog Box (p.961)), which is op ened fr om the Boundar y Conditions task page (as descr ibed in Setting C ell Z one and B oundar y Conditions (p.839)). Figur e 7.41: The P ressur e Far-F ield D ialo g Box 7.3.10.2.2. Defining Static P ressur e, Mach Numb er, and Static Temp eratur e To set the sta tic pr essur e and t emp erature at the far-field b oundar y in the Pressur e Far-F ield dialo g box, enter the appr opriate values f or Gauge P ressur e and Mach N umb er in the Momen tum tab . The M ach numb er can b e subsonic , sonic , or sup ersonic . Set the Temp erature in the Thermal tab . 7.3.10.2.3. Defining the F low D irection You c an define the flo w dir ection a t a pr essur e far-field b oundar y by setting the c omp onen ts of the direction v ector. If your geometr y is 2D non-axisymmetr ic en ter appr opriate values f or X and Y in the Pressur e Far-F ield dialo g box (Figur e 7.41: The P ressur e Far-F ield D ialog Box (p.961)). If your 961Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditionsgeometr y is 2D axisymmetr ic, enter the appr opriate values f or Axial ,Radial , and (if y ou ar e mo deling axisymmetr ic swir l) Tangen tial-C omp onen t of F low D irection . If your geometr y is 3D , you c an cho ose a Coordina te System tha t is Cartesian ,Cylindr ical, or Local C ylindr ical. In the C artesian c oordina te sy stem, enter the appr opriate values f or X,Y, and Z- Comp onen t of F low D irection . If the dir ection c osine da ta on the b oundar y is a vailable , then use the c ylindr ical or lo cal cylindr ical coordina te sy stem and sp ecify the Axial ,Radial ,Tangen tial- Comp onen t of F low D irection . For Cylindr ical, axis par amet ers need t o be sp ecified on the adjac ent cell z one of the b oundar y fac e. For Local C ylindr ical S wirl, specify the Axis Or igin and Axis D irection . 7.3.10.2.4. Defining Turbulenc e Paramet ers For turbulen t calcula tions , ther e ar e se veral w ays in which y ou c an define the turbulenc e par amet ers. Instr uctions f or deciding which metho d to use and det ermining appr opriate values f or these inputs are pr ovided in Determining Turbulenc e Paramet ers (p.914).Turbulenc e mo deling is descr ibed in Modeling Turbulenc e (p.1375 ). 7.3.10.2.5. Defining R adiation P aramet ers If you ar e using the P-1, DTRM, DO , sur face-to-sur face, or MC mo dels , you will set the Internal Emissivit y and (optionally) External Black B ody Temp erature M etho d. See Defining B oundar y Conditions f or R adia tion (p.1514 ) for details . 7.3.10.2.6. Defining Sp ecies Transp ort Paramet ers If you ar e mo deling sp ecies tr ansp ort, you will set the sp ecies mass or mole fr actions under Species Mass F ractions or Species M ole F ractions . See Defining C ell Z one and B oundar y Conditions f or Species (p.1649 ) for details . 7.3.10.3. Defining D iscr ete Phase B oundar y Conditions If you ar e mo deling a discr ete phase of par ticles , you c an set the fa te of par ticle tr ajec tories a t the pressur e far-field b oundar y. See Setting B oundar y Conditions f or the D iscrete Phase (p.1985 ) for details . 7.3.10.4. Default S ettings at P ressur e Far-Field B oundaries Default settings (in SI) f or pr essur e far-field b oundar y conditions ar e as f ollows: 0 Gauge P ressur e 0.6 Mach N umb er 300 Temp erature 1 X-C omp onen t of F low D irection 0 Y-C omp onen t of F low D irection 0 Z-Comp onen t of F low D irection 5% Turbulen t In tensit y 10 Turbulen t Visc osit y Ratio Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 962Cell Z one and B oundar y Conditions7.3.10.5. Calculation P rocedur e at P ressur e Far-Field B oundaries The pr essur e far-field b oundar y condition is a non-r eflec ting b oundar y condition based on the in tro- duc tion of R iemann in variants (tha t is, char acteristic v ariables) f or a one-dimensional flo w nor mal t o the b oundar y. For flo w tha t is subsonic ther e ar e two Riemann in variants, corresponding t o inc oming and out going w aves: (7.102) (7.103) wher e is the v elocity magnitude nor mal t o the b oundar y, is the lo cal sp eed of sound and is the r atio of sp ecific hea ts (ideal gas). The subscr ipt refers t o conditions b eing applied a t infinit y (the b oundar y conditions), and the subscr ipt refers t o conditions in the in terior of the domain (tha t is, in the c ell adjac ent to the b oundar y fac e).These t wo in variants can b e added and subtr acted t o give the f ollowing t wo equa tions: (7.104) (7.105) wher e and become the v alues of nor mal v elocity and sound sp eed applied on the b oundar y. At a fac e thr ough which flo w exits, the tangen tial v elocity comp onen ts and en tropy are extrapolated from the in terior; at an inflo w fac e, these ar e sp ecified as ha ving fr ee-str eam v alues . Using the v alues for , , tangen tial v elocity comp onen ts, and en tropy the v alues of densit y, velocity, temp erature, and pr essur e at the b oundar y fac e can b e calcula ted. 7.3.11. Outflo w B oundar y Conditions Outflo w b oundar y conditions in ANSY S Fluen t are used t o mo del flo w exits wher e the details of the flow velocity and pr essur e ar e not k nown pr ior t o solving the flo w pr oblem. You do not define an y conditions a t outflo w b oundar ies (unless y ou ar e mo deling r adia tive hea t transf er, a discr ete phase of particles , or split mass flo w): ANSY S Fluen t extrapolates the r equir ed inf ormation fr om the in terior. It is imp ortant, however, to understand the limita tions of this b oundar y type. Imp ortant Note tha t outflo w b oundar ies c annot b e used in the f ollowing c ases: •If a pr oblem includes pr essur e inlet b oundar ies; use pr essur e outlet b oundar y conditions (see Pressur e Outlet B oundar y Conditions (p.950)) inst ead. •If you ar e mo deling c ompr essible flo w. •If you ar e mo deling unst eady flo ws with v arying densit y (even if the fluid is inc ompr essible), it is pr eferable t o use a pr essur e outlet. In gener al, an outflo w condition ma y be used in inc ompr essible c ases using the E uler ian or Mixture multiphase mo dels . However, if the flo w ma y pr oduce a r ecircula tion a t the outlet or if the flo w field is not stable and fully de velop ed a t the outlet , then a pr essur e outlet boundar y condition is pr eferred. 963Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y ConditionsFor an o verview of flo w b oundar ies, see Flow Inlet and Exit B oundar y Conditions (p.913). 7.3.11.1. ANSY S Fluent ’s Treatment at O utflo w B oundaries The b oundar y conditions used b y ANSY S Fluen t at outflo w b oundar ies ar e as f ollows: •A zero diffusion flux f or all flo w variables . •An overall mass balanc e correction. The z ero diffusion flux c ondition applied a t outflo w cells means tha t the c onditions of the outflo w plane ar e extrapolated fr om within the domain and ha ve no impac t on the upstr eam flo w.The e xtra- polation pr ocedur e used b y ANSY S Fluen t up dates the outflo w velocity and pr essur e in a manner that is c onsist ent with a fully-de velop ed flo w assumption, as not ed b elow, when ther e is no ar ea change a t the outflo w b oundar y. The z ero diffusion flux c ondition applied b y ANSY S Fluen t at outflo w b oundar ies is appr oached physically in fully-de velop ed flo ws. Fully-de velop ed flo ws are flo ws in which the flo w velocity pr ofile (and/or pr ofiles of other pr operties such as t emp erature) is unchanging in the flo w dir ection. It is imp ortant to not e tha t gradien ts in the cr oss-str eam dir ection ma y exist a t an outflo w b oundar y. Only the diffusion flux es in the dir ection nor mal t o the e xit plane ar e assumed t o be zero. 7.3.11.2. Using O utflo w B oundaries As not ed in ANSY S Fluen t’s Treatmen t at Outflo w Boundar ies (p.964), the outflo w b oundar y condition is ob eyed in fully-de velop ed flo ws wher e the diffusion flux f or all flo w variables in the e xit dir ection are zero. However, you ma y also define outflo w b oundar ies a t ph ysical b oundar ies wher e the flo w is not fully de velop ed—and y ou c an do so with c onfidenc e if the assumption of a z ero diffusion flux a t the e xit is e xpected t o ha ve a small impac t on y our flo w solution. The appr opriate plac emen t of an outflo w b oundar y is descr ibed b y example b elow. •Outflo w boundar ies wher e nor mal gr adien ts ar e negligible: Figur e 7.42: Choic e of the Outflo w Boundar y Condition L ocation (p.965) sho ws a simple t wo-dimensional flo w pr oblem and se veral possible outflo w boundar y location choic es. Location C sho ws the outflo w boundar y located upstr eam of the plenum e xit but in a r egion of the duc t wher e the flo w is fully-de velop ed. At this lo cation, the outflo w boundar y con- dition is e xactly ob eyed. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 964Cell Z one and B oundar y ConditionsFigur e 7.42: Choic e of the Outflo w B oundar y Condition L ocation •Ill-posed outflo w boundar ies: Location B in Figur e 7.42: Choic e of the Outflo w Boundar y Condition L oca- tion (p.965) sho ws the outflo w boundar y near the r eattachmen t point of the r ecircula tion in the w ake of the back ward-facing st ep.This choic e of outflo w boundar y condition is ill-p osed as the gr adien ts nor mal to the e xit plane ar e quit e lar ge a t this p oint and c an b e expected t o ha ve a signific ant impac t on the flo w field upstr eam. Because the outflo w boundar y condition ignor es these axial gr adien ts in the flo w, location B is a p oor choic e for an outflo w boundar y.The e xit lo cation should b e mo ved do wnstr eam fr om the reattachmen t point. Figur e 7.42: Choic e of the Outflo w Boundar y Condition L ocation (p.965) sho ws a sec ond ill-p osed outflo w b oundar y at location A. Here, the outflo w is lo cated wher e flo w is pulled in to the ANSY S Fluen t domain thr ough the outflo w b oundar y. In situa tions lik e this the ANSY S Fluen t calcula tion typic ally do es not c onverge and the r esults of the c alcula tion ha ve no v alidit y.This is b ecause when flow is pulled in to the domain thr ough an outflo w, the mass flo w rate thr ough the domain is “floating ” or undefined . In addition, when flo w en ters the domain thr ough an outflo w b oundar y, the sc alar pr operties of the flo w ar e not defined . For e xample , the t emp erature of the flo w pulled in thr ough the outflo w is not defined . (ANSY S Fluen t cho oses the t emp erature using the t emp erature of the fluid adjac ent to the outflo w, inside the domain.) Therefore you should view all c alcula tions that involve flo w en tering the domain thr ough an outflo w b oundar y with sk epticism. For such calcula tions , pressur e outlet b oundar y conditions (see Pressur e Outlet B oundar y Conditions (p.950)) are recommended . Imp ortant Note tha t convergenc e ma y be aff ected if ther e is r ecircula tion thr ough the outflo w boundar y at an y point dur ing the c alcula tion, even if the final solution is not e xpected to ha ve an y flo w reentering the domain. This is par ticular ly tr ue of turbulen t flo w simu- lations . 965Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions7.3.11.3. Mass F low Split B oundar y Conditions In ANSY S Fluen t, it is p ossible t o use multiple outflo w b oundar ies and sp ecify the fr actional flo w rate through each b oundar y. In the Outflo w D ialog Box (p.3511 ), set the Flow R ate Weigh ting to indic ate wha t portion of the outflo w is thr ough the b oundar y. Figur e 7.43: The Outflo w D ialo g Box The Flow R ate Weigh ting is a w eigh ting fac tor: (7.106) By default , the Flow R ate Weigh ting for all outflo w b oundar ies is set t o 1. If the flo w is divided equally among all of y our outflo w b oundar ies (or if y ou ha ve just one outflo w b oundar y), you need not change the settings fr om the default; ANSY S Fluen t will sc ale the flo w rate fractions t o obtain equal fr actions thr ough all outflo w b oundar ies.Therefore, if y ou ha ve two outflo w b oundar ies and you w ant half of the flo w to exit thr ough each one , no inputs ar e requir ed fr om y ou. If, however, you want 75% of the flo w to exit thr ough one , and 25% thr ough the other , you will need t o explicitly specify both Flow R ate Weigh ting values , tha t is, 0.75 f or one b oundar y and 0.25 f or the other . Imp ortant If you sp ecify a Flow R ate Weigh ting of 0.75 a t the first e xit and lea ve the default Flow Rate Weigh ting (1.0) a t the sec ond e xit, then the flo w thr ough each b oundar y will b e Boundar y 1 = = 0.429 or 42.9% Boundar y 2 = = 0.571 or 57.1% 7.3.11.4. Other Inputs at O utflo w B oundaries 7.3.11.4.1. Radiation Inputs at O utflo w B oundaries In gener al, ther e ar e no b oundar y conditions f or y ou t o set a t an outflo w b oundar y. If, however, you are using the P-1, DTRM, DO , sur face-to-sur face, or MC mo dels , you will set the Internal E missivit y and (optionally) External Black B ody Temp erature M etho d in the Outflo w dialo g box.These Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 966Cell Z one and B oundar y Conditionsparamet ers ar e descr ibed in Defining B oundar y Conditions f or R adia tion (p.1514 ).The default v alue for Internal E missivit y is 1 and the default v alue f or Black B ody Temp erature is 300. 7.3.11.4.2. Defining D iscr ete Phase B oundar y Conditions If you ar e mo deling a discr ete phase of par ticles , you c an set the fa te of par ticle tr ajec tories a t the outflo w b oundar y. See Setting B oundar y Conditions f or the D iscrete Phase (p.1985 ) for details . 7.3.12. Outlet Vent Boundar y Conditions Outlet v ent boundar y conditions ar e used t o mo del an outlet v ent with a sp ecified loss c oefficien t and ambien t (dischar ge) pr essur e and t emp erature. 7.3.12.1. Inputs at O utlet Vent B oundaries You will en ter the f ollowing inf ormation f or an outlet v ent boundar y: •static pr essur e •backflo w conditions –total (stagna tion) t emp erature (for ener gy calcula tions) –backflo w pr essur e sp ecific ation –backflo w dir ection sp ecific ation metho d –turbulenc e par amet ers (f or turbulen t calcula tions) –chemic al sp ecies mass or mole fr actions (f or sp ecies c alcula tions) –mixture fraction and v arianc e (for non-pr emix ed or par tially pr emix ed c ombustion c alcula tions) –progress v ariable (f or pr emix ed or par tially pr emix ed c ombustion c alcula tions) –multiphase b oundar y conditions (f or gener al multiphase c alcula tions) –type of backflo w reference frame (not a vailable f or multiphase flo ws) •radia tion par amet ers (f or calcula tions using the P-1, DTRM, DO, surface-to-sur face, or MC mo dels) •discr ete phase b oundar y conditions (f or discr ete phase c alcula tions) •loss c oefficien t •open channel flo w par amet ers (f or op en channel flo w calcula tions using the VOF multiphase mo del) All values ar e en tered in the Outlet Vent Dialog Box (p.3513 ) (Figur e 7.44: The Outlet Vent Dialog Box (p.968)), which is op ened fr om the Boundar y Conditions task page (as descr ibed in Setting C ell Zone and B oundar y Conditions (p.839)). The first 4 it ems list ed ab ove ar e sp ecified in the same w ay tha t the y are sp ecified a t pressur e outlet boundar ies. See Inputs a t Pressur e Outlet B oundar ies (p.951) for details . Specific ation of the loss coefficien t is descr ibed her e. Open channel b oundar y condition inputs ar e descr ibed in Modeling Open C hannel F lows (p.2144 ). 967Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y ConditionsFigur e 7.44: The Outlet Vent Dialo g Box 7.3.12.1.1. Specifying the L oss C oefficient An outlet v ent is c onsider ed t o be infinit ely thin, and the pr essur e dr op thr ough the v ent is assumed to be pr oportional t o the d ynamic head of the fluid , with an empir ically det ermined loss c oefficien t that you supply .That is, the pr essur e dr op, , varies with the nor mal c omp onen t of v elocity thr ough the v ent, , as f ollows: (7.107) wher e is the fluid densit y, and is the nondimensional loss c oefficien t. Imp ortant is the pr essur e dr op in the dir ection of the flo w; ther efore the v ent will app ear as a resistanc e even in the c ase of backflo w. You c an define a constan t,polynomial ,piec ewise-linear , or piec ewise-p olynomial func tion f or the Loss C oefficien t across the v ent.The dialo g boxes for defining these func tions ar e the same as those used f or defining t emp erature-dep enden t properties. See Defining P roperties U sing Temp er- ature-Dependen t Functions (p.1095 ) for details . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 968Cell Z one and B oundar y Conditions7.3.13. Exhaust F an B oundar y Conditions Exhaust fan b oundar y conditions ar e used t o mo del an e xternal e xhaust fan with a sp ecified pr essur e jump and ambien t (dischar ge) pr essur e. Note The e xhaust fan b oundar y condition c onsiders only momen tum. Diffusion pr ocesses are not c onsider ed. 7.3.13.1. Inputs at E xhaust F an B oundaries You will en ter the f ollowing inf ormation f or an e xhaust fan b oundar y: •static pr essur e •backflo w conditions –total (stagna tion) t emp erature (for ener gy calcula tions) –backflo w pr essur e sp ecific ation –backflo w dir ection sp ecific ation metho d –turbulenc e par amet ers (f or turbulen t calcula tions) –chemic al sp ecies mass or mole fr actions (f or sp ecies c alcula tions) –mixture fraction and v arianc e (for non-pr emix ed or par tially pr emix ed c ombustion c alcula tions) –progress v ariable (f or pr emix ed or par tially pr emix ed c ombustion c alcula tions) –multiphase b oundar y conditions (f or gener al multiphase c alcula tions) –type of backflo w reference frame (not a vailable f or multiphase flo ws) –user-defined sc alar b oundar y conditions (f or user-defined sc alar c alcula tions) •radia tion par amet ers (f or calcula tions using the P-1, DTRM, DO, surface-to-sur face, or MC mo dels) •discr ete phase b oundar y conditions (f or discr ete phase c alcula tions) •pressur e jump •open channel flo w par amet ers (f or op en channel flo w calcula tions using the VOF multiphase mo del) All values ar e en tered in the Exhaust F an D ialog Box (p.3483 ) (Figur e 7.45: The Exhaust F an D ialog Box (p.970)), which is op ened fr om the Boundar y Conditions task page (as descr ibed in Setting C ell Zone and B oundar y Conditions (p.839)). The first 4 it ems list ed ab ove ar e sp ecified in the same w ay tha t the y are sp ecified a t pressur e outlet boundar ies. See Inputs a t Pressur e Outlet B oundar ies (p.951) for details . Specific ation of the pr essur e jump is descr ibed her e. Open channel b oundar y condition inputs ar e descr ibed in Modeling Op en Channel F lows (p.2144 ). 969Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions7.3.13.1.1. Specifying the P ressur e Jump An exhaust fan is c onsider ed t o be infinit ely thin, and the disc ontinuous pr essur e rise acr oss it is specified as a func tion of the lo cal fluid v elocity nor mal t o the fan. You c an define a constan t, polynomial ,piec ewise-linear , or piec ewise-p olynomial func tion f or the Pressur e Jump across the fan. The dialo g boxes for defining these func tions ar e the same as those used f or defining t emp er- ature-dep enden t properties. See Defining P roperties U sing Temp erature-Dependen t Functions (p.1095 ) for details . Figur e 7.45: The E xhaust F an D ialo g Box Imp ortant You must b e careful t o mo del the e xhaust fan so tha t a pr essur e rise o ccurs f or forward flow thr ough the fan. In the c ase of r eversed flo w, the fan is tr eated lik e an inlet v ent with a loss c oefficien t of unit y. 7.3.14. Degassing B oundar y Conditions Degassing b oundar y conditions ar e used t o mo del a fr ee sur face thr ough which disp ersed gas bubbles are allo wed t o esc ape, but the c ontinuous phase is not. A typic al applic ation is a bubble c olumn in which y ou w ant to reduc e computa tional c ost b y not including the fr eeboard region in the simula tion. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 970Cell Z one and B oundar y ConditionsWhen the degassing b oundar y condition is sp ecified f or an outlet , the c ontinuous liquid phase sees the b oundar y as a fr ee-slip w all and do es not lea ve the domain. The disp ersed gas phase sees the boundar y as an outlet. The outlet pr essur e is not sp ecified . Inst ead, ANSY S Fluen t aut oma tically sp ecifies a mass sink f or the disp ersed gas phase in the c ells adjac ent to the degassing outlet. The mass sink is calcula ted using the flux nor mal t o the b oundar y at the c ell c enter. Note The degassing b oundar y condition is only a vailable f or two-phase liquid-gas flo ws using the E uler ian multiphase mo del. 7.3.14.1. Limitations The f ollowing limita tions apply t o the degassing b oundar y condition in ANSY S Fluen t: •The degassing b oundar y condition is only a vailable f or liquid-gas t wo-phase flo w using the E uler ian model. The pr imar y phase must b e liquid . •In or der f or the gas t o esc ape from the degassing b oundar y, gravity must b e swit ched on in the mo del. •The degassing b oundar y condition is only r ecommended f or mo deling situa tions lik e bubble c olumns without the fr eeboard region. •When p ostpr ocessing on a degassing b oundar y, ther e is no nor mal v elocity for either phase sinc e the gas escape is mo deled b y a mass sink in the neighb oring c ells. 7.3.14.2. Inputs at D egassing B oundaries No inputs ar e nec essar y for the degassing b oundar y condition. However, the initial c ondition f or volume fr action must b e set appr opriately. It is r ecommended tha t the gas phase v olume fr action b e initializ ed with a nonz ero value smaller than the st eady-sta te gas holdup v alue . 7.3.15. Wall B oundar y Conditions Wall b oundar y conditions ar e used t o bound fluid and solid r egions . In visc ous flo ws, the no-slip boundar y condition is enf orced a t walls b y default , but y ou c an sp ecify a tangen tial v elocity comp onen t in terms of the tr ansla tional or r otational motion of the w all b oundar y, or mo del a “slip” wall b y sp e- cifying shear . (You c an also mo del a slip w all with z ero shear using the symmetr y boundar y type, but using a symmetr y boundar y will apply symmetr y conditions f or all equa tions . See Symmetr y Boundar y Conditions (p.997) for details .) The shear str ess and hea t transf er b etween the fluid and w all ar e comput ed based on the flo w details in the lo cal flo w field . 7.3.15.1. Inputs at Wall B oundaries 7.3.15.1.1. Summar y You will en ter the f ollowing inf ormation f or a w all b oundar y: •wall motion c onditions (f or mo ving or r otating w alls) 971Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions•shear c onditions (f or slip w alls, optional) •wall roughness (f or turbulen t flo ws, optional) •ther mal b oundar y conditions (f or hea t transf er calcula tions) •species b oundar y conditions (f or sp ecies c alcula tions) •chemic al reaction b oundar y conditions (f or sur face reactions) •radia tion b oundar y conditions (f or calcula tions using the P-1, DTRM, DO, surface-to-sur face, or MC models) •discr ete phase b oundar y conditions (f or discr ete phase c alcula tions) •wall adhesion c ontact angle (f or VOF c alcula tions , optional) •displac emen t boundar y conditions f or in trinsic fluid-str ucture in teraction (FSI) simula tions 7.3.15.2. Wall Motion Wall b oundar ies c an b e either sta tionar y or mo ving .The sta tionar y boundar y condition sp ecifies a fixed w all, wher eas the mo ving b oundar y condition c an b e used t o sp ecify the tr ansla tional or r ota- tional v elocity of the w all, or the v elocity comp onen ts. Wall motion c onditions ar e en tered in the Momen tum tab of the Wall D ialog Box (p.3549 ) (Fig- ure 7.46: The Wall D ialog Box for a M oving Wall (p.973)), which is op ened fr om the Boundar y Conditions Task P age (p.3479 ) (as descr ibed in Setting C ell Z one and B oundar y Conditions (p.839)).To view the wall motion c onditions , click the Momen tum tab . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 972Cell Z one and B oundar y ConditionsFigur e 7.46: The Wall D ialo g Box for a M oving Wall 7.3.15.2.1. Defining a Stationar y Wall For a sta tionar y wall, cho ose the Stationar y Wall option under Wall M otion . 7.3.15.2.2. Velocity Conditions for Mo ving Walls If you w ant to include tangen tial motion of the w all in y our c alcula tion, you need t o define the transla tional or r otational v elocity, or the v elocity comp onen ts. Selec t the Moving Wall option under Wall M otion .The Wall dialo g box will e xpand , as sho wn in Figur e 7.46: The Wall D ialog Box for a Moving Wall (p.973), to sho w the w all v elocity conditions . Note tha t you c annot use the mo ving w all c ondition t o mo del pr oblems wher e the w all motion with respect to the adjac ent cell z one has a c omp onen t tha t is nor mal t o the w all itself . For such pr oblems , consider using a S liding or D ynamic M esh appr oach as discussed in Modeling F lows Using S liding and D ynamic M eshes (p.1251 ). ANSY S Fluen t will neglec t an y nor mal c omp onen t of w all motion tha t you sp ecify using the metho ds b elow. •Specifying Rela tive or A bsolut e Velocity 973Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y ConditionsIf the c ell z one adjac ent to the w all is mo ving (f or e xample , if y ou ar e using a mo ving r eference frame or a sliding mesh), you c an cho ose t o sp ecify v elocities r elative to the z one motion b y en- abling the Rela tive to Adjac ent Cell Z one option. If you cho ose t o sp ecify r elative velocities , a velocity of z ero means tha t the w all is sta tionar y in the r elative frame , and ther efore mo ving a t the sp eed of the adjac ent cell z one in the absolut e frame . If you cho ose t o sp ecify absolut e velo- cities (b y enabling the Absolut e option), a velocity of z ero means tha t the w all is sta tionar y in the absolut e frame , and ther efore mo ving a t the sp eed of the adjac ent cell z one—but in the op- posite dir ection—in the r elative reference frame . Imp ortant If you ar e using one or mor e mo ving r eference frames , sliding meshes , or mixing planes , and y ou w ant the w all t o be fix ed in the mo ving fr ame , it is r ecommended tha t you specify r elative velocities (the default) r ather than absolut e velocities .Then, if y ou modify the sp eed of the adjac ent cell z one , you will not need t o mak e an y changes t o the w all v elocities , as y ou w ould if y ou sp ecified absolut e velocities . Note tha t if the adjac ent cell z one is not mo ving , the absolut e and r elative options ar e equiv alen t. •Transla tional Wall M otion For pr oblems tha t include linear tr ansla tional motion of the w all b oundar y (for e xample , a rectan- gular duc t with a mo ving b elt as one w all) y ou c an enable the Transla tional option and sp ecify the w all’s Speed and Direction (X,Y,Z vector). By default , wall motion is “disabled ” by the sp ecific- ation of Transla tional velocity with a Speed of z ero.You c an define time-v arying tr ansla tional speed using a tr ansien t profile ( Standar d Transien t Profiles (p.1067 )) or user-defined func tion f or the sp eed of the w all. If you need t o define nonlinear tr ansla tional motion, you will need t o use the Comp onen ts option, descr ibed b elow. •Rota tional Wall M otion For pr oblems tha t include r otational w all motion y ou c an enable the Rota tional option and define the r otational Speed about a sp ecified axis .To define the axis , set the Rota tion-A xis D irection and Rota tion-A xis Or igin .This axis is indep enden t of the axis of r otation used b y the adjac ent cell z one , and indep enden t of an y other w all rotation axis . For 3D pr oblems , the axis of r otation is the v ector passing thr ough the sp ecified Rota tion-A xis Or igin and par allel t o the v ector fr om (0,0,0) t o the ( X,Y,Z) point sp ecified under Rota tion-A xis D irection . For 2D pr oblems , you will specify only the Rota tion-A xis Or igin ; the axis of r otation is the -direction v ector passing thr ough the sp ecified p oint. For 2D axisymmetr ic pr oblems , you will not define the axis: the r otation will always be ab out the axis , with the or igin a t (0,0). You c an define time-v arying r otational sp eed using a tr ansien t profile ( Standar d Transien t Profiles (p.1067 )) profile or a user-defined func tion f or the sp eed of the w all. Note tha t the mo deling of tangen tial r otational motion will b e correct only if the w all b ounds a surface of r evolution ab out the pr escr ibed axis of r otation (f or e xample , a cir cle or c ylinder). Note also tha t rotational motion c an b e sp ecified f or a w all in a sta tionar y reference frame . •Wall M otion B ased on Velocity Comp onen ts For pr oblems tha t include linear or nonlinear tr ansla tional motion of the w all b oundar y you c an enable the Comp onen ts option and sp ecify the X-V elocity,Y-V elocity, and Z-Velocity of the Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 974Cell Z one and B oundar y Conditionswall.You c an define nonlinear tr ansla tional motion using a pr ofile or a user-defined func tion f or the X-V elocity,Y-V elocity, and/or Z-Velocity of the w all. •Wall M otion f or Two-Sided Walls As discussed ear lier in this sec tion, when y ou r ead a mesh with a t wo-sided w all z one (which f orms the in terface between fluid/solid r egions) in to ANSY S Fluen t, a “shado w” zone will aut oma tically be created so tha t each side of the w all is a distinc t wall z one . For two-sided w alls, it is p ossible to sp ecify diff erent motions f or the w all and shado w zones , whether or not the y are coupled . Note, however, tha t you c annot sp ecify motion f or a w all (or shado w) tha t is adjac ent to a solid zone . 7.3.15.2.3. Shear C onditions at Walls Four t ypes of shear c onditions ar e available: •no-slip •specified shear •specular ity coefficien t •Marangoni str ess The no-slip c ondition is the default , and it indic ates tha t the fluid sticks t o the w all and mo ves with the same v elocity as the w all, if it is mo ving .The sp ecified shear and M arangoni str ess b oundar y conditions ar e useful in mo deling situa tions in which the shear str ess (r ather than the motion of the fluid) is k nown. Examples of such situa tions ar e applied shear str ess, slip w all (z ero shear str ess), and free sur face conditions (z ero shear str ess or shear str ess dep enden t on sur face tension gr adien t). The sp ecified shear b oundar y condition allo ws you t o sp ecify the , , and comp onen ts of the shear str ess as c onstan t values or pr ofiles .The M arangoni str ess b oundar y condition allo ws you t o specify the gr adien t of the sur face tension with r espect to the t emp erature at this sur face.The shear stress is c alcula ted based on the sur face gr adien t of the t emp erature and the sp ecified sur face tension gradien t.The M arangoni str ess option is a vailable only f or c alcula tions in which the ener gy equa tion is being solv ed. The sp ecular ity coefficien t shear c ondition is sp ecific ally used in multiphase with gr anular flo ws.The specular ity coefficien t is a measur e of the fr action of c ollisions tha t transf er momen tum t o the w all and its v alue r anges b etween z ero and unit y.This implemen tation is based on the J ohnson and Jackson [54] (p.4008 ) boundar y conditions f or gr anular flo ws. Shear c onditions ar e en tered in the Momen tum tab of the Wall D ialog Box (p.3549 ), which is op ened from the Boundar y Conditions Task P age (p.3479 ) (as descr ibed in Setting C ell Z one and B oundar y Conditions (p.839)). 7.3.15.2.4. No-Slip Walls You c an mo del a no-slip w all b y selec ting the No Slip option under Shear C ondition .This is the default f or all w alls in visc ous flo ws. 7.3.15.2.5. Specified Shear In addition t o the no-slip w all tha t is the default f or visc ous flo ws, you c an mo del a slip w all b y specifying z ero or nonz ero shear . For nonz ero shear , the shear t o be sp ecified is the shear a t the 975Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditionswall b y the fluid .To sp ecify the shear , selec t the Specified S hear option under Shear C ondition (see Figur e 7.47: The Wall D ialog Box for S pecified S hear (p.976)).You c an then en ter , , and comp onen ts of shear under Shear S tress.Wall func tions f or turbulenc e ar e not used with the Spe- cified S hear option. Figur e 7.47: The Wall D ialo g Box for S pecified S hear 7.3.15.2.6. Specularit y Coefficient For multiphase gr anular flo w, you c an sp ecify the sp ecular ity coefficien t such tha t when the v alue is zero, this c ondition is equiv alen t to zero shear a t the w all, but when the v alue is near unit y, ther e is a signific ant amoun t of la teral momen tum tr ansf er.To sp ecify the sp ecular ity coefficien t, selec t the Specular ity Coefficien t option under Shear C ondition (see Figur e 7.48: The Wall D ialog Box for the S pecular ity Coefficien t (p.977)) and en ter the desir ed v alue in the t ext-en try box under Specular ity Coefficien t. Note The sp ecular ity coefficien t is not a vailable f or mo ving w alls. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 976Cell Z one and B oundar y ConditionsFigur e 7.48: The Wall D ialo g Box for the S pecular ity Coefficien t 7.3.15.2.7. Marangoni Str ess ANSY S Fluen t can also mo del shear str esses c aused b y the v ariation of sur face tension due t o tem- perature.The shear str ess applied a t the w all is giv en b y (7.108) wher e is the sur face tension gr adien t with r espect to temp erature, and is the sur face gradien t.This shear str ess is then applied t o the momen tum equa tion. To mo del M arangoni str ess f or the w all, selec t the Marangoni S tress option under Shear C ondition (see Figur e 7.49: The Wall D ialog Box for M arangoni S tress (p.978)).This option is a vailable only f or calcula tions in which the ener gy equa tion is b eing solv ed.You c an then en ter the sur face tension gradien t ( in Equa tion 7.108 (p.977)) in the Surface Tension G radien t field .Wall func tions for turbulenc e ar e not used with the Marangoni S tress option. 977Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y ConditionsFigur e 7.49: The Wall D ialo g Box for M arangoni S tress 7.3.15.2.8. Wall R oughness E ffec ts in Turbulent Wall-B ounded F lows Fluid flo ws over rough sur faces ar e enc oun tered in div erse situa tions . Examples ar e, among man y others , flows over the sur faces of air planes (esp ecially due t o ice accr etion), ships , turb omachiner y, heat exchangers , and piping sy stems , and a tmospher ic boundar y layers o ver terrain of v arying roughness .Wall roughness aff ects dr ag (r esistanc e) and hea t and mass tr ansf er on the w alls. If you ar e mo deling a turbulen t wall-b ounded flo w in which the w all roughness eff ects ar e consider ed to be signific ant, you c an include the w all roughness eff ects thr ough the Standar d La w-of-the-W all Modified f or R oughness (p.978) law-of-the-w all mo dified f or roughness or y ou c an use one of the Additional R oughness M odels f or Icing S imula tions (p.982). 7.3.15.2.8.1. Standar d Law-of-the-W all Mo dified for R oughness Experimen ts in r oughened pip es and channels indic ate tha t the mean v elocity distr ibution near rough w alls, when plott ed in the usual semi-lo garithmic sc ale, has the same slop e ( ) but a dif- ferent intercept (additiv e constan t in the lo g-la w).Therefore, the la w-of-the-w all for mean v elocity modified f or roughness has the f orm (7.109) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 978Cell Z one and B oundar y Conditionswher e and (7.110) wher e is a r oughness func tion tha t quan tifies the shif t of the in tercept due t o roughness eff ects. dep ends , in gener al, on the t ype (unif orm sand , rivets, threads , ribs, mesh-wir e, and so on) and size of the r oughness .There is no univ ersal r oughness func tion v alid f or all t ypes of r oughness . For a sand-gr ain r oughness and similar t ypes of unif orm roughness elemen ts, however, has b een found t o be well-c orrelated with the nondimensional r oughness heigh t, , wher e is the ph ysical roughness heigh t and . Analy ses of e xperimen tal da ta sho w tha t the roughness func tion is not a single func tion of , but tak es diff erent forms dep ending on the value . It has b een obser ved tha t ther e ar e thr ee distinc t regimes: •hydrodynamic ally smo oth ( ) •transitional ( ) •fully r ough ( ) According t o the da ta, roughness eff ects ar e negligible in the h ydrodynamic ally smo oth r egime , but become incr easingly imp ortant in the tr ansitional r egime , and tak e full eff ect in the fully r ough r egime . In ANSY S Fluen t, the whole r oughness r egime is sub divided in to the thr ee r egimes , and the f ormulas proposed b y Cebeci and B radsha w based on Nik uradse ’s da ta [22] (p.4006 ) are adopt ed t o comput e for each r egime . For the h ydrodynamic ally smo oth r egime ( ): (7.111) For the tr ansitional r egime ( ): (7.112) wher e is a r oughness c onstan t, and dep ends on the t ype of the r oughness . In the fully r ough r egime ( ): (7.113) In the solv er, given the r oughness par amet ers, is e valua ted using the c orresponding f ormula (Equa tion 7.111 (p.979),Equa tion 7.112 (p.979), or Equa tion 7.113 (p.979)).The mo dified la w-of-the- wall in Equa tion 7.109 (p.978) is then used t o evalua te the shear str ess a t the w all and other w all func tions f or the mean t emp erature and turbulen t quan tities . represen ts a do wnw ard shif t of the lo garithmic v elocity pr ofile , as sho wn in the f ollowing figur e: 979Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y ConditionsFigur e 7.50: Downw ard Shift of the L ogarithmic Velocity Profile This do wnw ard shif t leads t o a singular ity for lar ge r oughness heigh ts and lo w values of . Depending on the turbulenc e mo del and near w all tr eatmen t, two diff erent appr oaches ar e used in ANSY S Fluen t in or der t o avoid this issue: •reducing the r oughness heigh t as decr eases The first appr oach c onsists in r edefining the r oughness heigh t based on the mesh r efinemen t: (7.114) This ensur es tha t as appr oaches z ero, so t oo do es .Therefore, the mesh r equir emen t for rough w alls in this c ase is , in or der t o main tain the full eff ect of the r oughness on the flo w. •virtually shif ting the w all The sec ond appr oach is based on the obser vation tha t the visc ous subla yer is fully established only near h ydraulic ally smo oth w alls. In the tr ansitional r oughness r egime , the r oughness elemen ts are sligh tly thick er than the visc ous subla yer and star t to disturb it , so tha t in fully r ough flo ws, the subla yer is destr oyed and visc ous eff ects b ecome negligible .The f ollowing figur e illustr ates the equiv alen t sand-gr ain r oughness using a w all with a la yer of closely pack ed spher es, which have an a verage r oughness heigh t represen ting a t echnic al roughness with p eaks and v alleys of different shap es and siz es (see Schlich ting and G ersten [111] (p.4011 )): Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 980Cell Z one and B oundar y ConditionsFigur e 7.51: Illustr ation of E quiv alen t Sand-G rain Roughness It can b e assumed tha t the r oughness has a blo ckage eff ect, which is ab out 50% of its heigh t (not e tha t the figur e ab ove sho ws a t wo-dimensional cut of a thr ee-dimensional ar rangemen t). It is ther efore sensible t o vir tually shif t the w all t o 50% of the heigh t of the r oughness elemen ts. This r esults in a c orrected value f or the first c ell c enter: (7.115) which giv es ab out the c orrect displac emen t caused b y the sur face roughness .Thus the singular ity issue is a voided and fine meshes c an b e handled c orrectly. The sec ond appr oach (tha t is, virtually shif ting the w all) is the default tr eatmen t for rough w alls f or all t wo-equa tion turbulenc e mo dels based on the -equa tion and f or the f ollowing turbulenc e models based on the -equa tion, when the y are used with standar d and sc alable w all func tions (not e tha t the use of sc alable w all func tions is r ecommended o ver the use of standar d w all func tions): •standar d, RNG, and r ealizable - mo del •Reynolds str ess mo dels All other mo del c ombina tions with r ough w alls (f or e xample , the S palar t-Allmar as mo del) ha ve no special c alibr ation on fine meshes , and ther efore the first appr oach (r educing the r oughness heigh t as decr eases) is used . Note Rough w alls c annot b e used t ogether with the f ollowing mo del c ombina tions: •an -equa tion mo del with enhanc ed w all tr eatmen t or the M enter-L echner near-w all tr eatmen t Note tha t the f ollowing ar e the r elevant -equa tion mo dels: –all of the - mo dels (tha t is, standar d, RNG, and r ealizable) –the R eynolds str ess mo del with the Linear P ressur e-Strain mo del selec ted –the detached edd y simula tion (DES) mo del with the Realizable k-epsilon option selec ted •the R eynolds str ess mo del with the Stress-Omega or Stress-BSL mo del selec ted •the tr ansition - - mo del 981Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions•the lar ge edd y simula tion (LES) mo del Imp ortant Prior t o ANSY S Fluen t 14, the shif t descr ibed b y Equa tion 7.115 (p.981) was not applied when using turbulenc e mo dels based on the -equa tion. You c an r ecover the pr evious code b ehavior b y using the f ollowing scheme c ommand: (rpsetvar 'ke-rough-wall-treatment-r14? #f) (models-changed) 7.3.15.2.8.1.1. Setting the R oughness P aramet ers The r oughness par amet ers ar e in the Momen tum tab of the Wall D ialog Box (p.3549 ) (see Fig- ure 7.49: The Wall D ialog Box for M arangoni S tress (p.978)), which is op ened fr om the Boundar y Conditions Task P age (p.3479 ) (as descr ibed in Setting C ell Z one and B oundar y Conditions (p.839)). To mo del the w all roughness eff ects, you must sp ecify t wo roughness par amet ers: the Roughness Heigh t, , and the Roughness C onstan t, .The default r oughness heigh t ( ) is z ero, which c or- responds t o smo oth w alls. For the r oughness t o tak e eff ect, you must sp ecify a nonz ero value f or . For a unif orm sand-gr ain r oughness , the heigh t of the sand-gr ain c an simply b e tak en f or . For a non-unif orm sand-gr ain, however, the mean diamet er ( ) would b e a mor e meaning ful roughness heigh t. For other t ypes of r oughness , an “equiv alen t” sand-gr ain r oughness heigh t could be used f or .The ab ove appr oaches ar e only r elevant if the heigh t is c onsider ed c onstan t per surface. However, if the r oughness c onstan t or r oughness heigh t is not c onstan t, then y ou c an sp ecify a pr ofile (see Profiles (p.1051 )). Similar ly, user-defined func tions ma y be used t o define a w all roughness heigh t tha t is not c onstan t. For details on the f ormat of user-defined func tions , refer to the Fluen t Customiza tion M anual . Choosing a pr oper roughness c onstan t ( ) is dic tated mainly b y the t ype of the giv en r oughness . The default r oughness c onstan t ( ) was det ermined so tha t, when used with - turbulenc e models , it reproduces Nik uradse ’s resistanc e da ta for pip es roughened with tigh tly-pack ed, unif orm sand-gr ain r oughness .You ma y need t o adjust the r oughness c onstan t when the r oughness y ou want to mo del depar ts much fr om unif orm sand-gr ain. For instanc e, ther e is some e xperimen tal evidenc e tha t, for non-unif orm sand-gr ains , ribs, and wir e-mesh r oughness , a higher v alue ( ) is mor e appr opriate. Unfortuna tely, a clear guideline f or cho osing for arbitr ary types of roughness is not a vailable . Note The ad vantage of the r ough w all formula tion using a vir tual shif t of the w all (Equa- tion 7.115 (p.981)) compar ed t o reducing the r oughness heigh t as decr eases ( Equa- tion 7.114 (p.980)) is tha t it elimina tes all r estrictions with r espect to mesh r esolution near the w all, and c an ther efore be used on arbitr arily fine meshes . 7.3.15.2.8.2. Additional R oughness Mo dels for I cing S imulations Additional r oughness mo dels ar e available if y ou ha ve selec ted the Spalar t-Allmar as or the SST k- ω mo del in the Visc ous M odel dialo g box. See the Steps in U sing a Turbulenc e M odel (p.1392 ) for mor e inf ormation. With one of these visc ous mo dels ac tive, the additional r oughness mo dels will Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 982Cell Z one and B oundar y Conditionsbe available on the Wall boundar y condition panel on the Momen tum tab under Wall Roughness → Roughness M odels → High Roughness (Icing) . A discussion of the tr eatmen t of the turbulenc e models with the High Roughness (Icing) enabled is giv en in Treatmen t of the S palar t-Allmar as Model f or Icing S imula tions and Treatmen t of the SST M odel f or Icing S imula tions .These mo dels ar e primar ily designed and t ested f or simula tions of icing applic ations , however the y ma y also b e useful for other applic ations in which the b oundar y layer is fully r esolv ed and ther e is sur face roughness that is lar ge r elative to the near-w all mesh. Note tha t the High Roughness (Icing) mo dels ar e only v alid f or lo w-R e numb er turbulenc e, or need fine near-w all meshes (mesh should fully r esolv e the b oundar y layer). Figur e 7.52: The Wall D ialo g Box for High Roughness (Icing) Models You ha ve the f ollowing options: •Specified R oughness •NASA C orrelation •Shin-et-al •ICE3D R oughness F ile 7.3.15.2.8.2.1. Specified R oughness The Specified Roughness option is the same as in the Standar d roughness mo del. See Setting the Roughness P aramet ers (p.982) for mor e details . 983Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions7.3.15.2.8.2.2. NASA C orrelation If the NASA C orrelation option is selec ted, the sur face sand-gr ain r oughness heigh t is c omput ed with an empir ical NASA c orrelation f or icing in air flo ws [113] (p.4011 ).The sand-gr ain r oughness heigh t is c omput ed fr om the pr oduc t of the f ollowing c oefficien ts: (7.116) (7.117) (7.118) Where is the Free S tream Velocity, is the Free S tream Temp erature, LC is the Liquid C ontent (in most c ases w ater for ic e accr etion), c is the Characteristic L ength , and . The sand-gr ain r oughness heigh t is then obtained fr om the f ormula tion: (7.119) 7.3.15.2.8.2.3. Shin-et-al If the Shin-et-al option is selec ted the empir ical correlation f or the sur face sand-gr ain r oughness is comput ed with the S hin and B ond f ormula tion [113] (p.4011 ), which mo difies the NASA c orrelation (see the NASA C orrelation (p.984) for a descr iption of v ariables) with the f ollowing fac tor: (7.120) wher e MVD is the dr oplet mean diamet er (Droplet D iamet er).The c orresponding v alue of the sand- grain r oughness heigh t is obtained fr om: (7.121) 7.3.15.2.8.2.4. ICE3D R oughness F ile If the ICE3D Roughness F ile is selec ted, the sand-gr ain r oughness heigh t is r ead fr om a no de-based input file obtained fr om FENSAP-ICE .The file must ha ve the f ormat , and b e read in Fluen t via File → Read → Profile . After the FENSAP-ICE r oughness file is r ead in to Fluen t, the file name will app ear in the dr opdown list. 7.3.15.3. Thermal B oundar y Conditions at Walls When y ou ar e solving the ener gy equa tion, you need t o define ther mal b oundar y conditions a t wall boundar ies. Seven t ypes of ther mal c onditions ar e available: •fixed hea t flux Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 984Cell Z one and B oundar y Conditions•fixed t emp erature •convective hea t transf er •external r adia tion hea t transf er •combined e xternal r adia tion and c onvection hea t transf er •ther mal da ta tr ansf erred b etween another sy stem in Workbench using S ystem C oupling •ther mal c oupling acr oss a mapp ed in terface If the w all z one is a “two-sided w all” (a w all tha t forms the in terface between t wo regions , such as the fluid/solid in terface for a c onjuga te hea t transf er pr oblem) a subset of these ther mal c onditions will b e available , but y ou will also b e able t o cho ose whether or not the t wo sides of the w all ar e “coupled ”. See b elow for details . The inputs f or each t ype of ther mal c ondition ar e descr ibed b elow. If the w all has a nonz ero-thick ness , you should also set par amet ers f or c alcula ting thin-w all ther mal r esistanc e and hea t gener ation in the w all, as descr ibed b elow. You c an mo del c onduc tion within b oundar y walls and in ternal (tha t is, two-sided) w alls of y our model. This t ype of c onduc tion, called shell c onduc tion, allo ws you t o mor e convenien tly mo del hea t conduc tion on w alls wher e the w all thick ness is small with r espect to the o verall geometr y (for e xample , finned hea t exchangers or sheet metal in aut omobile under hoods). Meshing these w alls with solid cells w ould lead t o high-asp ect-ratio meshes and a signific ant incr ease in the t otal numb er of c ells. See b elow for details ab out shell c onduc tion. Thermal c onditions ar e en tered in the Thermal tab of the Wall D ialog Box (p.3549 ) (Figur e 7.53: The Wall D ialog Box (Thermal Tab) (p.985)), which is op ened fr om the Boundar y Conditions task page (as descr ibed in Setting C ell Z one and B oundar y Conditions (p.839)). Figur e 7.53: The Wall D ialo g Box (Thermal Tab) 985Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions7.3.15.3.1. Heat F lux B oundar y Conditions For a fix ed hea t flux c ondition, cho ose the Heat Flux option under Thermal C onditions .You will then need t o set the appr opriate value f or the hea t flux a t the w all sur face in the Heat Flux field . You c an define an adiaba tic w all b y setting a z ero hea t flux c ondition. This is the default c ondition for all w alls. 7.3.15.3.2. Temp eratur e Boundar y Conditions To selec t the fix ed t emp erature condition, cho ose the Temp erature option under Thermal C onditions in the Wall dialo g box.You will need t o sp ecify the t emp erature at the w all sur face (Temp erature). The hea t transf er to the w all is c omput ed using Equa tion 7.123 (p.995) or Equa tion 7.124 (p.995). 7.3.15.3.3. Convective Heat Transfer B oundar y Conditions For a c onvective hea t transf er w all b oundar y, selec t Convection under Thermal C onditions .Your inputs of Heat Transf er C oefficien t and Free S tream Temp erature will allo w ANSY S Fluen t to comput e the hea t transf er to the w all using Equa tion 7.127 (p.996). 7.3.15.3.4. External R adiation B oundar y Conditions If radia tion hea t transf er fr om the e xterior of y our mo del is of in terest, you c an enable the Radia tion option in the Wall dialo g box and set the External E missivit y and External R adia tion Temp erature. 7.3.15.3.5. Combined C onvection and E xternal R adiation B oundar y Conditions You c an cho ose a ther mal c ondition tha t combines the c onvection and r adia tion b oundar y conditions by selec ting the Mixed option. With this ther mal c ondition, you will need t o set the Heat Transf er Coefficien t,Free S tream Temp erature,External E missivit y, and External R adia tion Temp erature. 7.3.15.3.6. Augment ed H eat Transfer When mo deling the hea t transf er of applic ations tha t ha ve perturb ed flo w and/or disturb ed boundar y layers, it c an b e nec essar y to augmen t the c alcula tion of the diffusiv e hea t flux with a convective augmen tation fac tor. Such applic ations include the mo deling of under hood and underb ody heat loads , as w ells as tr ansien t hea t transf er in fully w armed-up e xhaust sy stems . The c onvective augmen tation fac tor represen ts the r atio of the measur ed N usselt numb er to the Nusselt numb er of an ideal flo w.You c an define it b y using the f ollowing t ext command: define → boundary-conditions → wall You will b e pr ompt ed t o define the Convective Augmentation Factor as either a pr ofile or a single v alue . Note tha t a v alue of 1 (the default v alue) r epresen ts no augmen tation of the diffusiv e heat flux, wher eas v alues gr eater than 1 initia te augmen tation. For fur ther details , see the equa tion for qid in DEFINE_HEAT_FLUX of the Fluen t Customiza tion M anual . 7.3.15.3.7. Thin-W all Thermal R esistanc e Paramet ers By default , a w all will ha ve a thick ness of z ero.You c an, however, in c onjunc tion with an y of the ther mal c onditions , mo del a thin la yer of ma terial on the w all. For e xample , you c an mo del the eff ect of a piec e of sheet metal b etween t wo fluid z ones , a coating on a solid z one , or c ontact resistanc e between t wo solid r egions . ANSY S Fluen t will solv e a 1D st eady hea t conduc tion equa tion t o comput e the ther mal r esistanc e off ered b y the w all and the hea t gener ation in the w all. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 986Cell Z one and B oundar y ConditionsTo include these eff ects in the hea t transf er calcula tion y ou will need t o sp ecify the t ype of ma terial, the thick ness of the w all, and the hea t gener ation r ate in the w all. Selec t the ma terial t ype in the Material N ame drop-do wn list , and sp ecify the thick ness in the Wall Thick ness field . If you w ant to check or mo dify the pr operties of the selec ted ma terial, you c an click Edit... to op en the Edit Material dialo g box; this dialo g box contains just the pr operties of the selec ted ma terial, not the full c ontents of the standar d Create/Edit M aterials dialo g box. When y ou sp ecify a thick ness , the w all is then tr eated as a c oupled w all, wher e the sur face tha t is adjac ent to the fluid / solid c ells is r eferred t o as the “wall sur face”. See Figur e 7.54: A Thin Wall (p.987). Figur e 7.54: A Thin Wall The ther mal r esistanc e of the w all is , wher e is the c onduc tivit y of the w all ma terial and is the w all thick ness .The ther mal w all b oundar y condition y ou set will b e sp ecified on the sur face that is separ ated fr om the fluid / solid c ells b y the w all thick ness .The t emp erature sp ecified a t this side of the w all is . Imp ortant Note tha t for thin w alls, you c an only sp ecify a c onstan t ther mal c onduc tivit y. If you w ant to use a non-c onstan t ther mal c onduc tivit y for a w all with nonz ero-thick ness , you should use the shell c onduc tion mo del (see Shell C onduc tion (p.989) for details). 987Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y ConditionsSpecify the hea t gener ation r ate inside the w all in the Heat Gener ation R ate field .This option is useful if , for e xample , you ar e mo deling pr inted cir cuit b oards wher e you k now the elec trical p ower dissipa ted in the cir cuits . When p ostpr ocessing a w all tha t has a thick ness but do es not ha ve shell c onduc tion enabled , the Temp erature... categor y pr ovides thr ee options: the t emp erature of the adjac ent fluid / solid c ells are stored as Static Temp erature; the t emp erature of the w all sur face itself is st ored as Wall Tem- perature; and the t emp erature of the sur face tha t is separ ated fr om the fluid / solid c ells b y the wall thick ness is st ored as Wall Temp erature (Thin) . If a mor e detailed analy sis of the solid z one and sur faces is r equir ed, then y ou should c onsider cr eating la yers of solid c ells in y our meshing ap- plication. 7.3.15.3.8. Thermal C onditions for Two-S ided Walls If the w all z one has a fluid or solid r egion on each side , it is c alled a “two-sided w all”.When y ou read a mesh with this t ype of w all z one in to ANSY S Fluen t, a “shado w” zone will aut oma tically b e created so tha t each side of the w all is a distinc t wall z one . In the Wall dialo g box, the shado w zone’s name will b e sho wn in the Shado w F ace Zone field .You c an cho ose t o sp ecify diff erent ther mal conditions on each z one , or t o couple the t wo zones: •To couple the t wo sides of the w all, selec t the Coupled option under Thermal C onditions . (This option will app ear in the Wall dialo g box only when the w all is a t wo-sided w all.) N o additional ther mal boundar y conditions ar e requir ed, because the solv er will c alcula te hea t transf er dir ectly fr om the solution in the adjac ent cells.You c an, however, specify the ma terial type, wall thick ness , and hea t gener ation rate for thin-w all ther mal r esistanc e calcula tions , as descr ibed ab ove. Note tha t the r esistanc e par amet ers you set f or one side of the w all will aut oma tically b e assigned t o its shado w w all z one . Specifying the heat gener ation r ate inside the w all is useful if , for e xample , you ar e mo deling pr inted cir cuit b oards wher e you k now the elec trical power dissipa ted in the cir cuits but not the hea t flux or w all temp erature. •To unc ouple the t wo sides of the w all and sp ecify diff erent ther mal c onditions on each one , cho ose Temp erature or Heat Flux as the ther mal c ondition t ype (Convection and Radia tion are not applic able for two-sided w alls); not e tha t this unc oupling will not b e eff ective if y ou ha ve enabled shell c onduc tion for the w all.The r elationship b etween the w all and its shado w will b e retained , so tha t you c an c ouple them again a t a la ter time , if desir ed.You will need t o set the r elevant par amet ers f or the selec ted ther mal condition, as descr ibed ab ove.The t wo unc oupled w alls c an ha ve diff erent thick nesses , and ar e eff ectively insula ted fr om one another . If you sp ecify a nonz ero wall thick ness f or the unc oupled w alls, the ther mal boundar y conditions y ou set will b e sp ecified f or each thin w all on the sur face tha t is separ ated fr om the fluid / solid c ells b y the w all thick ness , as sho wn in Figur e 7.55: Uncoupled Thin Walls (p.989), wher e is the Temp erature (or is the Heat Flux) specified on one w all and is the Temp erature (or is the Heat Flux) specified on the other w all. and are the ther mal c onduc tivities of the un- coupled thin w alls. Note tha t the gap b etween the w alls in Figur e 7.55: Uncoupled Thin Walls (p.989) is not par t of the mo del; it is included in the figur e only t o sho w wher e the ther mal b oundar y condition for each unc oupled w all is applied . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 988Cell Z one and B oundar y ConditionsFigur e 7.55: Uncoupled Thin Walls 7.3.15.3.9. Shell C onduc tion To enable shell c onduc tion f or a w all, enable the Shell C onduc tion option in the Wall boundar y condition dialo g box.You c an then click the Edit... butt on t o op en the Shell C onduc tion L ayers dialo g box, wher e you c an define the pr operties of the single or multiple la yers of the shell. Note that you must sp ecify a nonz ero wall thick ness f or e very layer of the shell. When shell c onduc tion is enabled , ANSY S Fluen t will c omput e hea t conduc tion f or the w all not only in the nor mal dir ection (which is alw ays comput ed when the ener gy equa tion is solv ed), but also in the planar dir ections . The Shell C onduc tion option will app ear in the Wall dialo g box for all w alls when solution of the ener gy equa tion is ac tive (e xcept f or mapp ed in terfaces). For inf ormation ab out ho w the ther mal conditions ar e applied on a w all with shell c onduc tion enabled , managing multiple shells , and postpr ocessing shell c onduc tion w alls, see Shell C onduc tion C onsider ations (p.1481 ). ANSY S Fluen t cases with shell c onduc tion c an b e read in ser ial or par allel. Either a par titioned or an unpar titioned c ase file c an b e read in par allel (see Mesh P artitioning and L oad B alancing (p.3067 ) for mor e inf ormation on par titioning). After reading a c ase file in par allel, shell z ones c an b e created on any wall. To convert every wall with a finit e thick ness in to a shell with a single ac tion, the TUI c ommand define/boundary-conditions/modify-zones/create-all-shell-threads can b e used; each c onverted shell will ha ve a single la yer with the same thick ness as the or iginal thin w all (any pr e-existing shells will not b e mo dified). To disable shell c onduc tion in e very wall with a single 989Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditionsaction, the TUI c ommand define/boundary-conditions/modify-zones/delete-all- shells can b e used .These c apabilities ar e available in b oth ser ial and par allel mo de. Imp ortant Note tha t the shell c onduc tion mo del has se veral limita tions: •It cannot b e applied on non-c onformal in terfaces, including mapp ed in terfaces. •It cannot b e applied on mo ving w all z ones . •It cannot b e used with FMG initializa tion. •Shell c onduc tion is not a vailable when the w all is set up t o receive ther mal da ta via S ystem Coupling . •It is a vailable only in 3D . •It is a vailable only when the pr essur e-based solv er is used . •Shells c annot b e split or mer ged . If you need t o split or mer ge a shell, disable the Shell C on- duc tion option f or the w all, perform the split or mer ge op eration, and then enable Shell Conduc tion for the new w all z ones . •The shell c onduc tion mo del c annot b e used on a w all z one tha t has under gone hanging node adaption. If you w ant to perform such adaption elsewher e in the c omputa tional domain, be sur e to use a b oolean op eration in an adaption e xpression t o exclude a regist er containing the w alls y ou ar e using f or shell c onduc tion. For e xample , NOT(region_0) . Refer to Adapting the M esh (p.2705 ) for additional inf ormation on adapting the mesh. •Fluxes a t the ends of a shell ar e not included in the hea t balanc e reports.These flux es ar e accoun ted f or correctly in the ANSY S Fluen t solution, but not in the flux r eport itself . •The junc tion of a w all with shell c onduc tion enabled and a non-c onformal c oupled w all is not supp orted. Such a junc tion will not b e ther mally c onnec ted, tha t is, ther e will b e no hea t transf er b etween the shell and the mesh in terface wall. •When r unning the par allel solv er with the shell c onduc tion mo del, not e tha t coupled w alls are enc apsula ted. If you enc oun ter pr oblems with the par titioning of the mesh, you c an tr y changing the enc apsula tion metho d to see if tha t resolv es the pr oblem (see Troublesho ot- ing (p.3093 ) for this and other tr oublesho oting options). 7.3.15.3.10. Heat Transfer B oundar y Conditions Through S ystem C oupling System C oupling allo ws the input and output of ther mal da ta fr om ANSY S Fluen t.When F luen t is coupled with another sy stem in Workbench using S ystem C oupling , you c an selec t the via S ystem Coupling option on the desir ed w all b oundar ies t o receive ther mal da ta thr ough S ystem C oupling service. Note tha t this option do es not need t o be selec ted t o pr ovide ther mal da ta fr om F luen t. For mor e details ab out setting up a simula tion with S ystem C oupling , see the Performing S ystem Coupling S imula tions U sing F luen t (p.3207 ) and the System C oupling U ser's G uide . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 990Cell Z one and B oundar y ConditionsWhen ther mal da ta is tr ansf erred in to Fluen t via S ystem C oupling , the f ollowing v ariables ar e available: •temp erature •heat flo w (hea t rate) When ther mal da ta is tr ansf erred out of F luen t via S ystem C oupling , the f ollowing v ariables ar e available: •temp erature •heat flo w (hea t rate) •heat transf er coefficien t (also k nown as “convection c oefficien t”) •near w all temp erature (also k nown as “bulk t emp erature” or “ambien t temp erature”) For each da ta tr ansf er, you sp ecify the t ype of da ta tr ansf er (the v ariables tr ansf erred) dur ing the System C oupling setup . As par t of standar d hea t transf er b oundar y condition settings in ANSY S Fluen t, you c an also sp ecify the t ype of ma terial, the thick ness of the w all, and the hea t gener ation r ate in the w all. Selec t the material t ype in the Material N ame drop-do wn list; if y ou w ant to check or mo dify the pr operties of the selec ted ma terial, you c an click Edit... to op en the Edit M aterial dialo g box (this dialo g box contains just the pr operties of the selec ted ma terial, and not the full c ontents of the standar d Cre- ate/Edit M aterials dialo g box).You c an sp ecify the thick ness in the Wall Thick ness numb er-en try box and the hea t gener ation r ate in the Heat Gener ation R ate numb er-en try box. Note A boundar y will b ehave in the same w ay as an adiaba tic b oundar y if the via S ystem Coupling option is enabled on this b oundar y, and ANSY S Fluen t is not r eceiving da ta from the c oupling da ta tr ansf er. Fluen t is not r eceiving c oupling da ta if it is either not involved with a S ystem C oupling simula tion, or if the c oupling is a one-w ay transf er with the F luen t analy sis only pr oviding da ta to the sec ond solv er. 7.3.15.3.11. Heat Transfer B oundar y Conditions A cross a M app ed Int erface Mapp ed in terfaces pr ovide a r obust appr oach f or mo deling c oupled w alls b etween z ones when the interface zones p enetr ate each other or ha ve gaps b etween them (see Figur e 7.56: 2D In terface with Penetr ation and G aps (p.992)). For the in terface wall b oundar y zones cr eated as par t of such in terfaces, via M app ed In terface is aut oma tically selec ted fr om the Thermal C onditions list in the Thermal tab of the Wall dialo g box, in or der t o in terpolate the ther mal da ta. Imp ortant Note tha t ther mal c oupling c alcula tions will not b e performed a t mapp ed in terfaces for the E uler ian multiphase mo del. For mor e details ab out mapp ed in terfaces, see The M app ed Option (p.749) and Using a N on-C on- formal M esh in ANSY S Fluen t (p.756). 991Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y ConditionsFigur e 7.56: 2D In terface with P enetr ation and G aps Such b oundar ies also allo w you t o sp ecify the standar d hea t transf er b oundar y condition settings , such as the t ype of ma terial, the thick ness of the w all, and the hea t gener ation r ate in the w all. Selec t the ma terial t ype in the Material N ame drop-do wn list; if y ou w ant to check or mo dify the pr operties of the selec ted ma terial, you c an click Edit... to op en the Edit M aterial dialo g box (this dialo g box contains just the pr operties of the selec ted ma terial, and not the full c ontents of the standar d Cre- ate/Edit M aterials dialo g box).You c an sp ecify the thick ness in the Wall Thick ness numb er-en try box and the hea t gener ation r ate in the Heat Gener ation R ate numb er-en try box. Note tha t the Shell C onduc tion option is not a vailable with the via M app ed In terface ther mal c ondition. 7.3.15.4. Species B oundar y Conditions for Walls By default , a zero-gr adien t condition f or all sp ecies is assumed a t walls (e xcept f or sp ecies tha t par ti- cipa te in sur face reactions), but it is also p ossible t o sp ecify sp ecies mass fr actions a t walls.That is, Dirichlet b oundar y conditions such as those tha t are sp ecified a t inlets c an b e used a t walls as w ell. If you w ant to retain the default z ero-gr adien t condition f or a sp ecies , no inputs ar e requir ed. If you want to sp ecify the mass fr action f or a sp ecies a t the w all, the st eps ar e as f ollows: 1.Click the Species tab in the Wall D ialog Box (p.3549 ) to view the sp ecies b oundar y conditions f or the w all (see Figur e 7.57: The Wall D ialog Box for S pecies B oundar y Condition Input (p.993)). 2.Under Species B oundar y Condition , selec t Specified M ass F raction (rather than Zero Diffusiv e Flux) in the dr op-do wn list t o the r ight of the sp ecies name .The dialo g box will e xpand t o include a field f or Species M ass F ractions . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 992Cell Z one and B oundar y ConditionsFigur e 7.57: The Wall D ialo g Box for S pecies B oundar y Condition Input 3.Under Species M ass F ractions , specify the mass fr action f or the sp ecies . The b oundar y condition t ype for each sp ecies is sp ecified separ ately, so y ou c an cho ose t o use diff erent metho ds for diff erent sp ecies . If you ar e mo deling sp ecies tr ansp ort with r eactions , you c an, alternatively, enable a r eaction mech- anism a t a w all b y tur ning on the Reac tion option and selec ting an a vailable mechanism fr om the Reac tion M echanisms drop-do wn list. See Defining Z one-B ased R eaction M echanisms (p.1642 ) for mor e inf ormation ab out defining r eaction mechanisms . You c an also mo del unr esolv ed sur face washc oats, which gr eatly incr ease the c atalytic sur face ar ea, by sp ecifying the Surface Area Washc oat Factor.The sur face washc oat incr eases the ar ea a vailable for sur face reaction. 7.3.15.4.1. Reac tion B oundar y Conditions for Walls If you ha ve enabled the mo deling of w all sur face reactions in the Species M odel D ialog Box (p.3294 ), you c an indic ate whether or not sur face reactions should b e ac tivated f or the w all. In the Species tab of the Wall dialo g box (Figur e 7.57: The Wall D ialog Box for S pecies B oundar y Condition In- put (p.993)), turn the Surface Reac tions option on or off . Note tha t a z ero-gr adien t condition is assumed a t the w all for sp ecies tha t do not par ticipa te in an y surface reactions . 7.3.15.5. Radiation B oundar y Conditions for Walls If you ar e using the gr ay P-1, DTRM, DO , sur face-to-sur face, or MC mo dels , you will need t o set the emissivit y of the w all ( Internal E missivit y) in the Thermal tab of the Wall dialo g box. If you ar e using the R osseland mo del y ou do not need t o set the emissivit y, because ANSY S Fluen t assumes the emissivit y is 1. 993Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y ConditionsFor the non-gr ay P-1, DO , or MC mo dels , specify a c onstan t Internal E missivit y for each w avelength band in the Radia tion tab of the Wall dialo g box (the default v alue in each band is 1). Alternatively, you c an sp ecify the in ternal emissivit y using a b oundar y condition par amet er (see Creating a N ew Paramet er (p.845)). If you ar e using the non-gr ay DO or MC mo dels , you will also need t o define the wall as opaque or semi-tr anspar ent in the Radia tion tab . See Defining B oundar y Conditions f or R adi- ation (p.1514 ) for details . If you ar e using the DO or MC mo dels , you c an enable a Boundar y Sour ce. 7.3.15.6. Discr ete Phase Mo del (DPM) B oundar y Conditions for Walls If you ar e mo deling a discr ete phase of par ticles , you c an set the fa te of par ticle tr ajec tories a t the wall in the DPM sec tion of the Wall dialo g box. See Setting B oundar y Conditions f or the D iscrete Phase (p.1985 ) for details . 7.3.15.6.1. Wall A dhesion C ontac t Angle for VOF Mo del If you ar e using the VOF mo del and y ou ar e mo deling w all adhesion, you c an sp ecify the c ontact angle f or each pair of phases a t the w all in the Momen tum tab of the Wall dialo g box. See Steps for S etting B oundar y Conditions (p.2124 ) for details . 7.3.15.7. User -Defined Sc alar (UDS) B oundar y Conditions for Walls If you ha ve defined UDS tr ansp ort equa tions in y our mo del, you c an sp ecify b oundar y conditions f or each equa tion in the UDS sec tion of the Wall dialo g box. See Setting U p UDS E qua tions in ANSY S Fluen t (p.1199 ) for details . 7.3.15.8. Wall F ilm C onditions for Walls If you ar e using the E uler ian Wall F ilm mo del (see Modeling E uler ian Wall F ilms (p.2337 ) for details), you c an set liquid film c onditions a t the w all in the Wall F ilm tab of the Wall dialo g box.This tab is available only if y ou ha ve enabled the E uler ian Wall F ilm mo del in the Models Task P age (p.3245 ). For details , see Setting E uler ian Wall F ilm S olution C ontrols (p.2342 ). 7.3.15.9. Struc tural Mo del C onditions for Walls For an in trinsic fluid-str ucture in teraction (FSI) simula tion, you c an set the displac emen t boundar y condition settings f or w alls tha t are adjac ent to solid c ell z ones in the Structure tab of the Wall dialo g box.This tab is only a vailable when a mo del is selec ted in the Structural M odel D ialog Box (p.3378 ). For details , see Setting U p an In trinsic F luid-S tructure In teraction (FSI) S imula tion (p.2330 ). 7.3.15.10. Default S ettings at Wall B oundaries The default ther mal b oundar y condition is a fix ed hea t flux of z ero.Walls ar e, by default , not mo ving . 7.3.15.11. Shear -Str ess C alculation P rocedur e at Wall B oundaries For no-slip w all c onditions , ANSY S Fluen t uses the pr operties of the flo w adjac ent to the w all/fluid boundar y to pr edic t the shear str ess on the fluid a t the w all. In laminar flo ws this c alcula tion simply dep ends on the v elocity gr adien t at the w all, while in turbulen t flo ws one of the appr oaches descr ibed in Near-W all Treatmen ts for Wall-B ounded Turbulen t Flows in the Theor y Guide is used . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 994Cell Z one and B oundar y ConditionsFor sp ecified-shear w alls, ANSY S Fluen t will c omput e the tangen tial v elocity at the b oundar y. If you ar e mo deling in viscid flo w with ANSY S Fluen t, all w alls use a slip c ondition, so the y are frictionless and e xert no shear str ess on the adjac ent fluid . 7.3.15.11.1. Shear -Str ess C alculation in L aminar F low In a laminar flo w, the w all shear str ess is defined b y the nor mal v elocity gr adien t at the w all as (7.122) When ther e is a st eep v elocity gr adien t at the w all, you must b e sur e tha t the mesh is sufficien tly fine t o accur ately r esolv e the b oundar y layer. Guidelines f or the appr opriate plac emen t of the near- wall no de in laminar flo ws are pr ovided in Mesh E lemen t Distribution (p.721). 7.3.15.11.2. Shear -Str ess C alculation in Turbulent F lows Wall tr eatmen ts for turbulen t flo ws are descr ibed in Near-W all Treatmen ts for Wall-B ounded Turbulen t Flows in the Theor y Guide . 7.3.15.12. Heat Transfer C alculations at Wall B oundaries 7.3.15.12.1. Temp eratur e Boundar y Conditions When a fix ed t emp erature condition is applied a t the w all, the hea t flux t o the w all fr om a fluid c ell is comput ed as (7.123) wher e = fluid-side lo cal hea t transf er coefficien t = w all sur face temp erature = lo cal fluid t emp erature = radia tive hea t flux Note tha t the fluid-side hea t transf er coefficien t is c omput ed based on the lo cal flo w-field c onditions (for e xample , turbulenc e level, temp erature, and v elocity pr ofiles), as descr ibed b y Equa- tion 7.130 (p.997). Heat transf er to the w all b oundar y from a solid c ell is c omput ed as (7.124) wher e = ther mal c onduc tivit y of the solid = lo cal solid t emp erature = distanc e between w all sur face and the solid c ell c enter 995Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions7.3.15.12.2. Heat F lux B oundar y Conditions When y ou define a hea t flux b oundar y condition a t a w all, you sp ecify the hea t flux a t the w all sur face. ANSY S Fluen t uses Equa tion 7.123 (p.995) and y our input of hea t flux t o det ermine the w all sur face temp erature adjac ent to a fluid c ell as (7.125) wher e, as not ed ab ove, the fluid-side hea t transf er coefficien t is c omput ed based on the lo cal flo w- field c onditions .When the w all b orders a solid r egion, the w all sur face temp erature is c omput ed as (7.126) 7.3.15.12.3. Convective Heat Transfer B oundar y Conditions When y ou sp ecify a c onvective hea t transf er coefficien t boundar y condition a t a w all, ANSY S Flu- ent uses y our inputs of the e xternal hea t transf er coefficien t and e xternal hea t sink t emp erature to comput e the hea t flux t o the w all as (7.127) wher e = e xternal hea t transf er coefficien t defined b y you = e xternal hea t-sink t emp erature defined b y you = radia tive hea t flux Equa tion 7.127 (p.996) assumes a w all of z ero-thick ness . 7.3.15.12.4. External R adiation B oundar y Conditions When the e xternal r adia tion b oundar y condition is used in ANSY S Fluen t, the hea t flux t o the w all is comput ed as (7.128) wher e = emissivit y of the e xternal w all sur face defined b y you = S tefan-B oltzmann c onstan t = sur face temp erature of the w all = temp erature of the r adia tion sour ce or sink on the e xterior of the domain, defined by you = radia tive hea t flux t o the w all fr om within the domain Equa tion 7.128 (p.996) assumes a w all of z ero-thick ness . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 996Cell Z one and B oundar y Conditions7.3.15.12.5. Combined E xternal C onvection and R adiation B oundar y Conditions When y ou cho ose the c ombined e xternal hea t transf er condition, the hea t flux t o the w all is c omput ed as (7.129) wher e the v ariables ar e as defined ab ove.Equa tion 7.129 (p.997) assumes a w all of z ero-thick ness . 7.3.15.12.6. Calculation of the F luid-S ide H eat Transfer C oefficient In laminar flo ws, the fluid side hea t transf er a t walls is c omput ed using F ourier’s law applied a t the walls. ANSY S Fluen t uses its discr ete form: (7.130) wher e is the lo cal coordina te nor mal t o the w all. For turbulen t flo ws, ANSY S Fluen t uses the la w-of-the-w all for temp erature der ived using the analo gy between hea t and momen tum tr ansf er [63] (p.4008 ). See Standar d Wall F unctions in the separ ate Theor y Guide for details . 7.3.16. Symmetr y Boundar y Conditions Symmetr y boundar y conditions ar e used when the ph ysical geometr y of in terest, and the e xpected pattern of the flo w/ther mal solution, have mir ror symmetr y.They can also b e used t o mo del z ero-shear slip w alls in visc ous flo ws.This sec tion descr ibes the tr eatmen t of the flo w at symmetr y planes and provides e xamples of the use of symmetr y.You do not define an y boundar y conditions a t symmetr y boundar ies, but y ou must tak e care to correctly define y our symmetr y boundar y locations . Imp ortant At the c enterline of an axisymmetr ic geometr y, you should use the axis b oundar y type rather than the symmetr y boundar y type, as illustr ated in Figur e 7.65: Use of an A xis Boundar y as the C enterline in an A xisymmetr ic G eometr y (p.1002 ). See Axis B oundar y Condi- tions (p.1002 ) for details . 7.3.16.1. Examples of S ymmetr y Boundaries Symmetr y boundar ies ar e used t o reduc e the e xtent of y our c omputa tional mo del t o a symmetr ic subsec tion of the o verall ph ysical sy stem. Figur e 7.58: Use of S ymmetr y to M odel One Q uarter of a 3D D uct (p.998) and Figur e 7.59: Use of S ymmetr y to M odel One Q uarter of a C ircular C ross-S ec- tion (p.998) illustr ate two examples of symmetr y boundar y conditions used in this w ay. 997Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y ConditionsFigur e 7.58: Use of S ymmetr y to M odel One Q uar ter of a 3D D uct Figur e 7.59: Use of S ymmetr y to M odel One Q uar ter of a C ircular C ross-S ection Figur e 7.60: Inappr opriate Use of S ymmetr y (p.999) illustr ates two pr oblems in which a symmetr y plane w ould b e inappr opr iate. In b oth e xamples , the pr oblem geometr y is symmetr ic but the flo w itself does not ob ey the symmetr y boundar y conditions . In the first e xample , buo yancy creates an asym- metr ic flo w. In the sec ond , swir l in the flo w cr eates a flo w nor mal t o the w ould-b e symmetr y plane . Note tha t this sec ond e xample should b e handled using r otationally p eriodic b oundar ies (as illustr ated in Figur e 7.61: Use of P eriodic B oundar ies t o Define S wirling F low in a C ylindr ical Vessel (p.1000 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 998Cell Z one and B oundar y ConditionsFigur e 7.60: Inappr opr iate Use of S ymmetr y 7.3.16.2. Calculation P rocedur e at S ymmetr y Boundaries ANSY S Fluen t assumes a z ero flux of all quan tities acr oss a symmetr y boundar y.There is no c onvective flux acr oss a symmetr y plane: the nor mal v elocity comp onen t at the symmetr y plane is ther efore zero.There is no diffusion flux acr oss a symmetr y plane: the nor mal gr adien ts of all flo w variables ar e ther efore zero at the symmetr y plane .The symmetr y boundar y condition c an ther efore be summar ized as follows: •zero nor mal v elocity at a symmetr y plane •zero nor mal gr adien ts of all v ariables a t a symmetr y plane As sta ted ab ove, these c onditions det ermine a z ero flux acr oss the symmetr y plane , which is r equir ed by the definition of symmetr y. Since the shear str ess is z ero at a symmetr y boundar y, it c an also b e interpreted as a “slip” wall when used in visc ous flo w calcula tions . 7.3.17. Periodic B oundar y Conditions Periodic b oundar y conditions ar e used when the ph ysical geometr y of in terest and the e xpected pa ttern of the flo w/ther mal solution ha ve a p eriodically r epeating na ture.Two types of p eriodic c onditions are available in ANSY S Fluen t.The first t ype do es not allo w a pr essur e dr op acr oss the p eriodic planes . (Note to FL UENT 4 users: This t ype of p eriodic b oundar y is r eferred t o as a “cyclic” boundar y in FL UENT 4.) The sec ond t ype allo ws a pr essur e dr op t o occur acr oss tr ansla tionally p eriodic b oundar ies, enabling you t o mo del “fully-de velop ed” periodic flo w. (In FL UENT 4 this is a “periodic” boundar y.) This sec tion discusses the no-pr essur e-dr op p eriodic b oundar y condition. A c omplet e descr iption of the fully-de velop ed p eriodic flo w mo deling c apabilit y is pr ovided in Periodic F lows (p.1206 ). 999Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions7.3.17.1. Examples of P erio dic B oundaries Periodic b oundar y conditions ar e used when the flo ws acr oss t wo opp osite planes in y our c omputa- tional mo del ar e iden tical.Figur e 7.61: Use of P eriodic B oundar ies t o Define S wirling F low in a C yl- indr ical Vessel (p.1000 ) illustr ates a t ypic al applic ation of p eriodic b oundar y conditions . In this e xample the flo w en tering the c omputa tional mo del thr ough one p eriodic plane is iden tical to the flo w exiting the domain thr ough the opp osite periodic plane . Periodic planes ar e alw ays used in pairs as illustr ated in this e xample . Figur e 7.61: Use of P eriodic B oundar ies t o D efine S wirling F low in a C ylindr ical Vessel 7.3.17.2. Inputs for P erio dic B oundaries For a p eriodic b oundar y without an y pr essur e dr op, ther e is only one input y ou need t o consider : whether the geometr y is r otationally or tr ansla tionally p eriodic. (Additional inputs ar e requir ed f or a periodic flo w with a p eriodic pr essur e dr op. See Periodic F lows (p.1206 ).) Rotationally p eriodic b oundar ies ar e boundar ies tha t form an included angle ab out the c enterline of a rotationally symmetr ic geometr y.Figur e 7.61: Use of P eriodic B oundar ies t o Define S wirling F low in a Cylindr ical Vessel (p.1000 ) illustr ates rotational p eriodicit y.Transla tionally p eriodic b oundar ies ar e boundar ies tha t form p eriodic planes in a r ectilinear geometr y.Figur e 7.62: Example of Transla tional Periodicit y - P hysical D omain (p.1000 ) illustr ates tr ansla tionally p eriodic b oundar ies. Figur e 7.62: Example of Transla tional P eriodicit y - P hysical D omain Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1000Cell Z one and B oundar y ConditionsFigur e 7.63: Example of Transla tional P eriodicit y - M odeled D omain You will sp ecify tr ansla tional or r otational p eriodicit y for a p eriodic b oundar y in the Periodic D ialog Box (p.3517 ) (Figur e 7.64: The P eriodic D ialog Box (p.1001 )), which is op ened fr om the Boundar y Condi- tions task page (as descr ibed in Setting C ell Z one and B oundar y Conditions (p.839)). Figur e 7.64: The P eriodic D ialo g Box Note tha t ther e will b e an additional it em in the Periodic dialo g box for the densit y-based solv er, which allo ws you t o sp ecify the p eriodic pr essur e jump . See Periodic F lows (p.1206 ) for details . If the domain is r otationally p eriodic, selec t Rota tional as the Periodic Type; if it is tr ansla tionally periodic, selec t Transla tional . For rotationally p eriodic domains , the solv er will aut oma tically c omput e the angle thr ough which the p eriodic z one is r otated.The axis used f or this r otation is the axis of rotation sp ecified f or the adjac ent cell z one . Note tha t ther e is no need f or the adjac ent cell z one t o be mo ving f or y ou t o use a r otationally p eri- odic b oundar y.You c ould , for e xample , mo del pip e flo w in 3D using a sta tionar y reference frame with a pie-slic e of the pip e; the sides of the slic e would r equir e rotational p eriodicit y. Click the Check butt on in the Mesh group b ox of the Domain tab (see Check ing the M esh (p.788)) to comput e and displa y the minimum, maximum, and a verage r otational angles of all fac es on p eri- odic b oundar ies. If the diff erence between the minimum, maximum, and a verage v alues is not negli- gible , then ther e is a pr oblem with the mesh: the mesh geometr y is not p eriodic ab out the sp ecified axis. 1001Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions7.3.17.3. Default S ettings at P erio dic B oundaries By default , all p eriodic b oundar ies ar e transla tional. 7.3.17.4. Calculation P rocedur e at P erio dic B oundaries ANSY S Fluen t treats the flo w at a p eriodic b oundar y as though the opp osing p eriodic plane is a dir ect neighb or to the c ells adjac ent to the first p eriodic b oundar y.Therefore, when c alcula ting the flo w through the p eriodic b oundar y adjac ent to a fluid c ell, the flo w conditions a t the fluid c ell adjac ent to the opp osite periodic plane ar e used . 7.3.18. Axis B oundar y Conditions The axis b oundar y type must b e used as the c enterline of an axisymmetr ic geometr y (see Figur e 7.65: Use of an A xis B oundar y as the C enterline in an A xisymmetr ic G eometr y (p.1002 )). It can also b e used f or the c enterline of a c ylindr ical-p olar quadr ilateral or he xahedr al mesh (f or e xample , a mesh cr eated f or a str uctured-mesh c ode such as FL UENT 4). You do not need t o define an y boundar y conditions a t axis b oundar ies. Imp ortant When cr eating 2D axisymmetr ic geometr y, the axis b oundar y must lie on the y=0 line . Figur e 7.65: Use of an A xis B oundar y as the C enterline in an A xisymmetr ic G eometr y 7.3.18.1. Calculation P rocedur e at A xis B oundaries To det ermine the appr opriate ph ysical value f or a par ticular v ariable a t a p oint on the axis , ANSY S Fluen t uses the c ell v alue in the adjac ent cell. 7.3.19. Fan B oundar y Conditions The fan mo del is a lump ed par amet er mo del tha t can b e used t o det ermine the impac t of a fan with known char acteristics up on some lar ger flo w field .The fan b oundar y type allo ws you t o input an em- pirical fan cur ve tha t go verns the r elationship b etween head (pr essur e rise) and flo w rate (velocity) across a fan elemen t.You c an also sp ecify r adial and tangen tial c omp onen ts of the fan swir l velocity. The fan mo del do es not pr ovide an accur ate descr iption of the detailed flo w thr ough the fan blades . Instead, it pr edic ts the amoun t of flo w thr ough the fan. Fans ma y be used in c onjunc tion with other Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1002Cell Z one and B oundar y Conditionsflow sour ces, or as the sole sour ce of flo w in a simula tion. In the la tter case, the sy stem flo w rate is determined b y the balanc e between losses in the sy stem and the fan cur ve. ANSY S Fluen t also pr ovides a c onnec tion f or a sp ecial user-defined fan mo del tha t up dates the pr essur e jump func tion dur ing the c alcula tion. This f eature is descr ibed in User-D efined F an M odel (p.1043 ). 7.3.19.1. Fan E quations 7.3.19.1.1. Mo deling the P ressur e Rise A cross the F an A fan is c onsider ed t o be infinit ely thin, and the disc ontinuous pr essur e rise acr oss it is sp ecified as a func tion of the v elocity thr ough the fan. The r elationship ma y be a c onstan t, a p olynomial, piec ewise- linear , or piec ewise-p olynomial func tion, or a user-defined func tion. In the c ase of a p olynomial, the r elationship is of the f orm (7.131) wher e is the pr essur e jump , are the pr essur e-jump p olynomial c oefficien ts, and is the magnitude of the lo cal fluid v elocity nor mal t o the fan. Imp ortant The v elocity can b e either p ositiv e or nega tive.You must b e careful t o mo del the fan so tha t a pr essur e rise o ccurs f or forward flo w thr ough the fan. You c an, optionally , use the mass-a veraged v elocity nor mal t o the fan t o det ermine a single pr essur e- jump v alue f or all fac es in the fan z one . 7.3.19.1.2. Mo deling the F an S wirl Velocity For thr ee-dimensional pr oblems , the v alues of the c onvected tangen tial and r adial v elocity fields can b e imp osed on the fan sur face to gener ate swir l.These v elocities c an b e sp ecified as func tions of the r adial distanc e from the fan c enter.The r elationships ma y be constan t or p olynomial func tions , or user-defined func tions . Imp ortant You must use SI units f or all fan swir l velocity inputs . For the c ase of p olynomial func tions , the tangen tial and r adial v elocity comp onen ts can b e sp ecified by the f ollowing equa tions: (7.132) (7.133) 1003Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditionswher e and are, respectively, the tangen tial and r adial v elocities on the fan sur face in m/s , and are the tangen tial and r adial v elocity polynomial c oefficien ts, and is the distanc e to the fan c enter. 7.3.19.2. User Inputs for F ans Onc e the fan z one has b een iden tified (in the Boundar y Conditions task page), you will set all modeling inputs f or the fan in the Fan D ialog Box (p.3488 ) (Figur e 7.66: The F an D ialog Box (p.1004 )), which is op ened fr om the Boundar y Conditions Task P age (p.3479 ) (as descr ibed in Setting C ell Z one and B oundar y Conditions (p.839)). Figur e 7.66: The F an D ialo g Box Inputs f or a fan ar e as f ollows: 1.Iden tify the fan z one . 2.Define the pr essur e jump acr oss the fan. 3.Define the discr ete phase b oundar y condition f or the fan (f or discr ete phase c alcula tions). 4.Define the swir l velocity, if desir ed (3D only). 7.3.19.2.1. Identifying the F an Z one Since the fan is c onsider ed t o be infinit ely thin, it must b e mo deled as the in terface between c ells, rather than a c ell z one .Therefore the fan z one is a t ype of in ternal fac e zone (wher e the fac es ar e line segmen ts in 2D or tr iangles/quadr ilaterals in 3D). If, when y ou r ead y our mesh in to ANSY S Fluen t, the fan z one is iden tified as an interior zone , right-click the z one in the tr ee and use the Type sub- menu t o change it t o a fan zone (f or mor e details , see Changing C ell and B oundar y Zone Types (p.837)). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1004Cell Z one and B oundar y ConditionsOnc e the in terior z one has b een changed t o a fan z one , you c an op en the Fan dialo g box and sp ecify the pr essur e jump and , optionally , the swir l velocity. 7.3.19.2.2. Defining the P ressur e Jump To define the pr essur e jump , you will sp ecify a p olynomial, piec ewise-linear , or piec ewise-p olynomial func tion of v elocity, a user-defined func tion, or a c onstan t value .You should also check the Zone Average D irection vector to be sur e tha t a pr essur e rise o ccurs f or forward flo w thr ough the fan. The Zone A verage D irection , calcula ted b y the solv er, is the fac e-averaged dir ection v ector for the fan z one . If this v ector is p ointing in the dir ection y ou w ant the fan t o blo w, do not selec t Reverse Fan D irection ; if it is p ointing in the opp osite dir ection, selec t Reverse F an D irection . 7.3.19.2.2.1. Polynomial, Piecewise-Linear , or P iecewise-P olynomial F unc tion Follow these st eps t o set a p olynomial, piec ewise-linear , or piec ewise-p olynomial func tion f or the pressur e jump: 1.Check tha t the Profile S pecific ation of P ressur e-Jump option is off in the Fan D ialog Box (p.3488 ). 2.Choose polynomial ,piec ewise-linear , or piec ewise-p olynomial in the dr op-do wn list t o the r ight of Pressur e-Jump . (If the func tion t ype you w ant is alr eady selec ted, you c an click the Edit... butt on t o open the dialo g box wher e you will define the func tion.) 3.In the dialo g box tha t app ears f or the definition of the Pressur e Jump func tion (f or e xample ,Fig- ure 7.67: Polynomial P rofile D ialog Box for P ressur e Jump D efinition (p.1005 )), enter the appr opriate values . These pr ofile input dialo g boxes ar e used the same w ay as the pr ofile input dialo g boxes for temp erature- dep enden t properties. See Defining P roperties U sing Temp erature-Dependen t Functions (p.1095 ) to find out ho w to use them. Figur e 7.67: Polynomial P rofile D ialo g Box for P ressur e Jump D efinition 4.Set an y of the optional par amet ers descr ibed b elow. (optional) When y ou define the pr essur e jump using an y of these t ypes of func tions , you c an cho ose t o limit the minimum and maximum v elocity magnitudes used t o calcula te the pr essur e jump . Enabling the 1005Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y ConditionsLimit P olynomial Velocity Range option limits the pr essur e jump when a Min Velocity M agnitude and a Max Velocity M agnitude are sp ecified . Imp ortant The v alues c orresponding t o the Min Velocity M agnitude and the Max Velocity M ag- nitude do not limit the flo w field v elocity to this r ange . However, this r ange do es limit the v alue of the pr essur e jump , which is a p olynomial and a func tion of v elocity, as seen in Equa tion 7.131 (p.1003 ). If the c alcula ted nor mal v elocity magnitude e xceeds the Max Velocity M agnitude tha t has b een sp ecified , then the pr essur e jump a t the Max Velocity Magnitude value will b e used . Similar ly, if the c alcula ted v elocity is less than the sp ecified Min Velocity M agnitude , the pr essur e jump a t the Min Velocity M agnitude will b e substitut ed f or the pr essur e jump c orresponding t o the c alcula ted v elocity. You also ha ve the option t o use the mass-a veraged v elocity nor mal t o the fan t o det ermine a single pressur e-jump v alue f or all fac es in the fan z one .Turning on Calcula te Pressur e-Jump fr om A verage Conditions enables this option. 7.3.19.2.2.2. Constant Value To define a c onstan t pressur e jump , follow these st eps: 1.Turn off the Profile S pecific ation of P ressur e-Jump option in the Fan D ialog Box (p.3488 ). 2.Choose constan t in the dr op-do wn list t o the r ight of Pressur e-Jump . 3.Enter the v alue f or in the Pressur e-Jump field . You c an f ollow the pr ocedur e below, if it is mor e convenien t: 1.Turn on the Profile S pecific ation of P ressur e-Jump option. 2.Selec t constan t in the dr op-do wn list b elow Pressur e Jump P rofile , and en ter the v alue f or in the Pressur e Jump P rofile field . 7.3.19.2.2.3. User -Defined F unc tion or P rofile For a user-defined pr essur e-jump func tion or a func tion defined in a b oundar y pr ofile file , you will follow these st eps: 1.Turn on the Profile S pecific ation of P ressur e-Jump option. 2.Choose the appr opriate func tion in the dr op-do wn list b elow Pressur e Jump P rofile . See the Fluen t Customiza tion M anual for inf ormation ab out user-defined func tions , and Profiles (p.1051 ) for details ab out pr ofile files . 7.3.19.2.2.4. Example: Determining the P ressur e Jump F unc tion This e xample sho ws you ho w to det ermine the func tion f or the pr essur e jump . Consider the simple two-dimensional duc t flo w illustr ated in Figur e 7.68: A F an L ocated In a 2D D uct (p.1007 ). Air at constan t densit y en ters the 2.0 m 0.4 m duc t with a v elocity of 15 m/s . Centered in the duc t is a fan. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1006Cell Z one and B oundar y ConditionsFigur e 7.68: A F an L ocated In a 2D D uct Assume tha t the fan char acteristics ar e as f ollows when the fan is op erating a t 2000 r pm: (Pa) ( /s) 0.0 25 175 20 350 15 525 10 700 5 875 0 wher e is the flo w thr ough the fan and is the pr essur e rise acr oss the fan. The fan char acteristics in this e xample f ollow a simple linear r elationship b etween pr essur e rise and flo w rate.To convert this in to a r elationship b etween pr essur e rise and v elocity, the cr oss-sec tional ar ea of the fan must be known. In this e xample , assuming tha t the duc t is 1.0 m deep , this ar ea is 0.4 m2, so tha t the corresponding v elocity values ar e as f ollows: (Pa) (m/s) 0.0 62.5 175 50.0 350 37.5 525 25.0 700 12.5 875 0 The p olynomial f orm of this r elationship is the f ollowing equa tion f or a line: (7.134) 7.3.19.2.3. Defining D iscr ete Phase B oundar y Conditions for the F an If you ar e mo deling a discr ete phase of par ticles , you c an set the fa te of par ticle tr ajec tories a t the fan. See Setting B oundar y Conditions f or the D iscrete Phase (p.1985 ) for details . 7.3.19.2.4. Defining the F an S wirl Velocity If you w ant to set tangen tial and r adial v elocity fields on the fan sur face to gener ate swir l in a 3D problem, follow these st eps: 1007Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions1.Turn on the Swirl-Velocity Specific ation option in the Fan D ialog Box (p.3488 ). 2.Specify the fan ’s axis of r otation b y defining the axis or igin ( Fan Or igin ) and dir ection v ector (Fan A xis). 3.Set the v alue f or the r adius of the fan ’s hub ( Fan Hub R adius ).The default is to avoid division by zero in the p olynomial. 4.Set the tangen tial and r adial v elocity func tions as p olynomial func tions of r adial distanc e, constan t values , or user-defined func tions . Imp ortant You must use SI units f or all fan swir l velocity inputs . 7.3.19.2.4.1. Polynomial F unc tion To define a p olynomial func tion f or tangen tial or r adial v elocity, follow the st eps b elow: 1.Check tha t the Profile S pecific ation of Tangen tial Velocity or Profile S pecific ation of R adial Velocity option is off in the Fan D ialog Box (p.3488 ). 2.Enter the c oefficien ts in Equa tion 7.132 (p.1003 ) or in Equa tion 7.133 (p.1003 ) in the Tangen tial- or Radial-V elocity Polynomial C oefficien ts field . Enter first , then , and so on. Separ ate each c oef- ficien t by a blank spac e. Rememb er tha t the first c oefficien t is f or . 7.3.19.2.4.2. Constant Value To define a c onstan t tangen tial or r adial v elocity, the st eps ar e as f ollows: 1.Turn on the Profile S pecific ation of Tangen tial Velocity or Profile S pecific ation of R adial Velocity option in the Fan D ialog Box (p.3488 ). 2.Selec t constan t in the dr op-do wn list under Tangen tial or Radial Velocity Profile . 3.Enter the v alue f or or in the Tangen tial or Radial Velocity Profile field . You c an f ollow the pr ocedur e below, if it is mor e convenien t: 1.Turn off the Profile S pecific ation of Tangen tial Velocity or Profile S pecific ation of R adial Velocity option in the Fan D ialog Box (p.3488 ). 2.Enter the v alue f or or in the Tangen tial- or Radial-V elocity Polynomial C oefficien ts field . 7.3.19.2.4.3. User -Defined F unc tion or P rofile For a user-defined tangen tial or r adial v elocity func tion or a func tion c ontained in a pr ofile file , follow the pr ocedur e below: 1.Turn on the Profile S pecific ation of Tangen tial or Radial Velocity option. 2.Choose the appr opriate func tion fr om the dr op-do wn list under Tangen tial or Radial Velocity Profile . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1008Cell Z one and B oundar y ConditionsSee the Fluen t Customiza tion M anual for inf ormation ab out user-defined func tions , and Profiles (p.1051 ) for details ab out pr ofile files . 7.3.19.3. Postpr ocessing for F ans 7.3.19.3.1. Reporting the P ressur e Rise Through the F an You c an use the Surface In tegrals D ialog Box (p.3726 ) to report the pr essur e rise thr ough the fan, as descr ibed in Surface In tegration (p.2947 ).There ar e two steps t o this pr ocedur e: 1.Create a sur face on each side of the fan z one . Use the Transf orm Sur face Dialog Box (p.3935 ) (as descr ibed in Transf orming Sur faces (p.2753 )) to transla te the fan z one sligh tly upstr eam and sligh tly do wnstr eam to create two new sur faces. 2.In the Surface In tegrals dialo g box, report the a verage Static P ressur e just upstr eam and just do wn- stream of the fan. You c an then c alcula te the pr essur e rise thr ough the fan. 7.3.19.3.2. Graphic al P lots Graphic al reports of in terest with fans ar e as f ollows: •Contours or pr ofiles of Static P ressur e and Static Temp erature. •XY plots of Static P ressur e and Static Temp erature vs position. Displa ying G raphics (p.2775 ) explains ho w to gener ate gr aphic al displa ys of da ta. Imp ortant When gener ating these plots , be sur e to tur n off the displa y of no de v alues so tha t you can see the diff erent values on each side of the fan. (If you displa y no de v alues , the c ell values on either side of the fan will b e averaged t o obtain a no de v alue , and y ou will not see, for e xample , the pr essur e jump acr oss the fan.) 7.3.20. Radia tor B oundar y Conditions A lump ed-par amet er mo del f or a hea t exchange elemen t (for e xample , a radia tor or c ondenser), is available in ANSY S Fluen t.The r adia tor b oundar y type allo ws you t o sp ecify b oth the pr essur e dr op and hea t transf er coefficien t as func tions of the v elocity nor mal t o the r adia tor. A mor e detailed hea t exchanger mo del is also a vailable in ANSY S Fluen t. See Modeling H eat Ex- changers (p.1573 ) for details . 7.3.20.1. Radiat or E quations 7.3.20.1.1. Mo deling the P ressur e Loss Through a R adiat or A radia tor is c onsider ed t o be infinit ely thin, and the pr essur e dr op thr ough the r adia tor is assumed to be pr oportional t o the d ynamic head of the fluid , with an empir ically det ermined loss c oefficien t that you supply .That is, the pr essur e dr op, , varies with the nor mal c omp onen t of v elocity thr ough the r adia tor, , as f ollows: 1009Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions(7.135) wher e is the fluid densit y, and is the non-dimensional loss c oefficien t, which c an b e sp ecified as a c onstan t or as a p olynomial, piec ewise-linear , or piec ewise-p olynomial func tion. In the c ase of a p olynomial, the r elationship is of the f orm (7.136) wher e are polynomial c oefficien ts and is the magnitude of the lo cal fluid v elocity nor mal t o the r adia tor. 7.3.20.1.2. Mo deling the H eat Transfer Through a R adiat or The hea t flux fr om the r adia tor to the sur rounding fluid is giv en as (7.137) wher e is the hea t flux, is the t emp erature do wnstr eam of the hea t exchanger (r adia tor), and is the r adia tor temp erature.The c onvective hea t transf er coefficien t, , can b e sp ecified as a constan t or as a p olynomial, piec ewise-linear , or piec ewise-p olynomial func tion. For a p olynomial, the r elationship is of the f orm (7.138) wher e are polynomial c oefficien ts and is the magnitude of the lo cal fluid v elocity nor mal t o the r adia tor in m/s . To define the ac tual hea t flux , specify a Temp erature of absolut e zero (0 K, 0 °R, –273.15 °C, –459.67 °F), and set the c onstan t Heat Flux value . To define the r adia tor temp erature, enter the v alue f or in the Temp erature field .To define the Heat-Transf er-C oefficien t , you c an sp ecify a p olynomial, piec ewise-linear , or piec ewise-p olyno- mial func tion of v elocity, or a c onstan t value . (either the en tered v alue or the v alue c alcula ted using Equa tion 7.137 (p.1010 )) is in tegrated o ver the r adia tor sur face ar ea. Fluen t do es not allo w you t o sp ecify a v alue less than absolut e zero for the r adia tor temp erature. 7.3.20.1.2.1. Calculating the H eat Transfer C oefficient To mo del the ther mal b ehavior of the r adia tor, you must supply an e xpression f or the hea t transf er coefficien t, , as a func tion of the fluid v elocity thr ough the r adia tor, .To obtain this e xpression, consider the hea t balanc e equa tion: (7.139) wher e Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1010Cell Z one and B oundar y Conditions = hea t flux ( W/ ) = fluid mass flo w rate (kg/s) = sp ecific hea t capacit y of fluid ( J/kg-K) = empir ical hea t transf er coefficien t (W/ -K) = e xternal t emp erature (reference temp erature for the liquid) (K) = temp erature do wnstr eam fr om the hea t exchanger (K) = hea t exchanger fr ontal ar ea ( ) Equa tion 7.139 (p.1010 ) can b e rewritten as (7.140) wher e is the upstr eam air t emp erature.The hea t transf er coefficien t, , can ther efore be com- puted as (7.141) or, in t erms of the fluid v elocity, (7.142) 7.3.20.2. User Inputs for R adiat ors Onc e the r adia tor z one has b een iden tified (in the Boundar y Conditions task page), you will set all modeling inputs f or the r adia tor in the Radia tor D ialog Box (p.3537 ) (Figur e 7.69: The R adia tor D ialog Box (p.1011 )), which is op ened fr om the Boundar y Conditions Task P age (p.3479 ) (as descr ibed in Setting Cell Z one and B oundar y Conditions (p.839)). Figur e 7.69: The R adia tor D ialo g Box 1011Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y ConditionsThe inputs f or a r adia tor ar e as f ollows: 1.Iden tify the r adia tor zone . 2.Define the pr essur e loss c oefficien t. 3.Define either the hea t flux or the hea t transf er coefficien t and r adia tor temp erature. If defining the heat flux, specify the Temp eratureas absolut e zero. 4.Define the discr ete phase b oundar y condition f or the r adia tor (f or discr ete phase c alcula tions). 7.3.20.2.1. Identifying the R adiat or Z one Since the r adia tor is c onsider ed t o be infinit ely thin, it must b e mo deled as the in terface between cells, rather than a c ell z one .Therefore the r adia tor z one is a t ype of in ternal fac e zone (wher e the faces ar e line segmen ts in 2D or tr iangles/quadr ilaterals in 3D). If, when y ou r ead y our mesh in to ANSY S Fluen t, the r adia tor z one is iden tified as an interior zone , right-click the z one in the tr ee and use the Type sub-menu t o change it t o a radia tor zone (f or mor e details , see Changing C ell and Boundar y Zone Types (p.837)). Onc e the in terior z one has b een changed t o a r adia tor z one , you c an op en the Radia tor dialo g box and sp ecify the loss c oefficien t and hea t flux inf ormation. 7.3.20.2.2. Defining the P ressur e Loss C oefficient F unc tion To define the pr essur e loss c oefficien t you c an sp ecify a p olynomial, piec ewise-linear , or piec ewise- polynomial func tion of v elocity, or a c onstan t value . 7.3.20.2.2.1. Polynomial, Piecewise-Linear , or P iecewise-P olynomial F unc tion Follow these st eps t o set a p olynomial, piec ewise-linear , or piec ewise-p olynomial func tion f or the pressur e loss c oefficien t: 1.Choose polynomial ,piec ewise-linear , or piec ewise-p olynomial in the dr op-do wn list t o the r ight of Loss C oefficien t. (If the func tion t ype you w ant is alr eady selec ted, you c an click the Edit... butt on t o open the dialo g box wher e you will define the func tion.) 2.In the dialo g box tha t app ears f or the definition of the Loss C oefficien t func tion (f or e xample ,Fig- ure 7.70: Polynomial P rofile D ialog Box for Loss C oefficien t Definition (p.1013 )), enter the appr opriate values .These pr ofile input dialo g boxes ar e used the same w ay as the pr ofile input dialo g boxes for temp erature-dep enden t properties. See Defining P roperties U sing Temp erature-Dependen t Func- tions (p.1095 ) to find out ho w to use them. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1012Cell Z one and B oundar y ConditionsFigur e 7.70: Polynomial P rofile D ialo g Box for L oss C oefficien t Definition 7.3.20.2.2.2. Constant Value To define a c onstan t loss c oefficien t, follow these st eps: 1.Choose constan t in the Loss C oefficien t drop-do wn list. 2.Enter the v alue f or in the Loss C oefficien t field . 7.3.20.2.2.3. Example: Calculating the L oss C oefficient This e xample sho ws you ho w to det ermine the loss c oefficien t func tion. Consider the simple t wo- dimensional duc t flo w of air thr ough a w ater-c ooled r adia tor, sho wn in Figur e 7.71: A S imple D uct with a R adia tor (p.1013 ). Figur e 7.71: A S imple D uct with a R adia tor The r adia tor char acteristics must b e known empir ically. For this c ase, assume tha t the r adia tor to be modeled yields the t est da ta sho wn in Table 7.2: Air-side R adia tor D ata (p.1014 ), which w as tak en with a waterside flo w rate of 7 k g/min and an inlet w ater temp erature of 400.0 K. To comput e the loss coefficien t, it is helpful t o constr uct a table with v alues of the d ynamic head , , as a func tion of pressur e dr op, , and the r atio of these t wo values , (from Equa tion 7.135 (p.1010 )). (The air 1013Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditionsdensit y, defined in Figur e 7.71: A S imple D uct with a R adia tor (p.1013 ), is 1.0 k g/ .) The r educ ed da ta are sho wn in Table 7.3: Reduc ed R adia tor D ata (p.1014 ). Table 7.2: Air-side R adia tor D ata Pressur e D rop Downstr eam Temp (K) Upstr eam Temp (K) Velocity (m/s) 75.0 330.0 300.0 5.0 250.0 322.5 300.0 10.0 450.0 320.0 300.0 15.0 Table 7.3: Reduc ed R adia tor D ata (Pa) (Pa)v (m/s) 6.0 75.0 12.5 5.0 5.0 250.0 50.0 10.0 4.0 450.0 112.5 15.0 The loss c oefficien t is a linear func tion of the v elocity, decr easing as the v elocity incr eases .The f orm of this r elationship is (7.143) wher e is no w the absolut e value of the v elocity thr ough the r adia tor. 7.3.20.2.3. Defining the H eat F lux P aramet ers As men tioned in Radia tor E qua tions (p.1009 ), you c an either define the ac tual hea t flux in the Heat Flux field , or set the hea t transf er coefficien t and r adia tor temp erature . All inputs ar e in the Radia tor D ialog Box (p.3537 ). To define the ac tual hea t flux, specify a Temp erature of 0 K, and set the c onstan t Heat Flux value . To define the r adia tor temp erature, enter the v alue f or in the Temp erature field .To define the Heat-Transf er-C oefficien t, you c an sp ecify a p olynomial, piec ewise-linear , or piec ewise-p olynomial func tion of v elocity, or a c onstan t value . 7.3.20.2.3.1. Polynomial, Piecewise-Linear , or P iecewise-P olynomial F unc tion Follow these st eps t o set a p olynomial, piec ewise-linear , or piec ewise-p olynomial func tion f or the heat transf er coefficien t: 1.Choose polynomial ,piec ewise-linear , or piec ewise-p olynomial in the dr op-do wn list t o the r ight of Heat-Transf er-C oefficien t. (If the func tion t ype you w ant is alr eady selec ted, you c an click the Edit... butt on t o op en the dialo g box wher e you will define the func tion.) 2.In the dialo g box tha t app ears f or the definition of the Heat-Transf er-C oefficien t func tion, enter the appr opriate values .These pr ofile input dialo g boxes ar e used the same w ay as the pr ofile input dialo g boxes for temp erature-dep enden t properties. See Defining P roperties U sing Temp erature-Dependen t Functions (p.1095 ) to find out ho w to use them. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1014Cell Z one and B oundar y Conditions7.3.20.2.3.2. Constant Value To define a c onstan t hea t transf er coefficien t, follow these st eps: 1.Choose constan t in the Heat-Transf er-C oefficien t drop-do wn list. 2.Enter the v alue f or in the Heat-Transf er-C oefficien t field . 7.3.20.2.3.3. Example: Determining the H eat Transfer C oefficient F unc tion This e xample sho ws you ho w to det ermine the func tion f or the hea t transf er coefficien t. Consider the simple t wo-dimensional duc t flo w of air thr ough a w ater-c ooled r adia tor, sho wn in Figur e 7.71: A Simple D uct with a R adia tor (p.1013 ). The da ta supplied in Table 7.2: Air-side R adia tor D ata (p.1014 ) along with v alues f or the air densit y (1.0 k g/ ) and sp ecific hea t (1000 J/k g-K) c an b e used t o obtain the f ollowing v alues f or the hea t transf er coefficien t : (W/ -K) Velocity (m/s) 2142.9 5.0 2903.2 10.0 3750.0 15.0 The hea t transf er coefficien t ob eys a sec ond-or der p olynomial r elationship (fit t o the p oints in the table ab ove) with the v elocity, which is of the f orm (7.144) Note tha t the v elocity is assumed t o be the absolut e value of the v elocity passing thr ough the radia tor. 7.3.20.2.4. Defining D iscr ete Phase B oundar y Conditions for the R adiat or If you ar e mo deling a discr ete phase of par ticles , you c an set the fa te of par ticle tr ajec tories a t the radia tor. See Setting B oundar y Conditions f or the D iscrete Phase (p.1985 ) for details . 7.3.20.3. Postpr ocessing for R adiat ors 7.3.20.3.1. Reporting the R adiat or P ressur e Drop You c an use the Surface In tegrals D ialog Box (p.3726 ) to report the pr essur e dr op acr oss the r adia tor, as descr ibed in Surface In tegration (p.2947 ).There ar e two steps t o this pr ocedur e: 1.Create a sur face on each side of the r adia tor zone . Use the Transf orm Sur face Dialog Box (p.3935 ) (as descr ibed in Transf orming Sur faces (p.2753 )) to transla te the r adia tor zone sligh tly upstr eam and sligh tly downstr eam t o create two new sur faces. 2.In the Surface In tegrals dialo g box, report the a verage Static P ressur e just upstr eam and just do wn- stream of the r adia tor.You c an then c alcula te the pr essur e dr op acr oss the r adia tor. To check this v alue against the e xpected v alue based on Equa tion 7.135 (p.1010 ), you c an use the Surface In tegrals dialo g box to report the a verage nor mal v elocity thr ough the r adia tor. (If the r a- diator is not aligned with the , , or axis , you will need t o use the Custom F ield F unction C alcu- 1015Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditionslator D ialog Box (p.3797 ) to gener ate a func tion f or the v elocity nor mal t o the r adia tor.) Onc e you have the a verage nor mal v elocity, you c an use Equa tion 7.136 (p.1010 ) to det ermine the loss c oefficien t and then Equa tion 7.135 (p.1010 ) to calcula te the e xpected pr essur e loss . 7.3.20.3.2. Reporting H eat Transfer in the R adiat or To det ermine the t emp erature rise acr oss the r adia tor, follow the pr ocedur e outlined ab ove for the pressur e dr op t o gener ate sur faces upstr eam and do wnstr eam of the r adia tor.Then use the Surface Integrals D ialog Box (p.3726 ) (as f or the pr essur e dr op r eport) to report the a verage Static Temp erature on each sur face.You c an then c alcula te the t emp erature rise acr oss the r adia tor. 7.3.20.3.3. Graphic al P lots Graphic al reports of in terest with r adia tors ar e as f ollows: •Contours or pr ofiles of Static P ressur e and Static Temp erature. •XY plots of Static P ressur e and Static Temp erature vs position. Displa ying G raphics (p.2775 ) explains ho w to gener ate gr aphic al displa ys of da ta. Imp ortant When gener ating these plots , be sur e to tur n off the displa y of no de v alues so tha t you can see the diff erent values on each side of the r adia tor. (If you displa y no de v alues , the cell v alues on either side of the r adia tor will b e averaged t o obtain a no de v alue , and y ou will not see , for e xample , the pr essur e loss acr oss the r adia tor.) 7.3.21. Porous Jump B oundar y Conditions Porous jump c onditions ar e used t o mo del a thin “membr ane” tha t has k nown v elocity (pr essur e-dr op) char acteristics . It is essen tially a 1D simplific ation of the p orous media mo del a vailable f or c ell z ones . Examples of uses f or the p orous jump c ondition include mo deling pr essur e dr ops thr ough scr eens and filt ers, and mo deling r adia tors when y ou ar e not c oncerned with hea t transf er.This simpler mo del should b e used whene ver p ossible (inst ead of the full p orous media mo del) b ecause it is mor e robust and yields b etter convergenc e. The thin p orous medium has a finit e thick ness o ver which the pr essur e change is defined as a c ombin- ation of D arcy’s La w and an additional iner tial loss t erm: (7.145) wher e is the laminar fluid visc osity, is the p ermeabilit y of the medium, is the pr essur e-jump coefficien t, is the v elocity nor mal t o the p orous fac e, and is the thick ness of the medium. Appro- priate values f or and can b e calcula ted using the t echniques descr ibed in User Inputs f or P orous Media (p.872). In a c oupled analy sis in volving F luen t and S ystem C oupling , data can b e transf erred t o and fr om the porous jump b oundar y. For mor e ab out S ystem C oupling , see Performing S ystem C oupling S imula tions Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1016Cell Z one and B oundar y ConditionsUsing F luen t (p.3207 ). For mor e inf ormation ab out the da ta tr ansf erred, see Force transf erred t o System Coupling fr om a P orous J ump B oundar y (p.3212 ). Note •The p orous jump b oundar y condition c onsiders only the momen tum r esistanc e. Diffusion pr o- cesses ar e not c onsider ed. •In some c ases , the pr essur e-based c oupled solv er with p orous jump b oundar y conditions ma y suffer fr om c onvergenc e issues tha t do not r espond t o changes in the c oupled solv er settings . This b ehavior dep ends on the sp ecific flo w configur ation and p orous jump b oundar y condition values . If convergenc e instabilit y is obser ved using the c oupled pr essur e-based solv er, it is r e- commended tha t you change the pr essur e-velocity coupling t o one of the segr egated schemes . 7.3.21.1. User Inputs for the P orous Jump Mo del Onc e the p orous jump z one has b een iden tified (in the Boundar y Conditions task page), you will set all mo deling inputs f or the p orous jump in the Porous J ump D ialog Box (p.3518 ) (Figur e 7.72: The Porous J ump D ialog Box (p.1017 )), which is op ened fr om the Boundar y Conditions Task P age (p.3479 ) (as descr ibed in Setting C ell Z one and B oundar y Conditions (p.839)). Figur e 7.72: The P orous Jump D ialo g Box The inputs r equir ed f or the p orous jump mo del ar e as f ollows: 1.Iden tify the p orous-jump z one . 2.Set the Face Permeabilit y of the medium ( in Equa tion 7.145 (p.1016 )). 3.Set the Porous M edium Thick ness ( ). 1017Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions4.Set the Pressur e-Jump C oefficien t ( ). Note The unit f or the pr essur e-jump c oefficien t (C2) is the in verse of length. Should y ou want to define diff erent units , you c an do so b y op ening the Units dialo g box and se- lecting length-in verse from the Quan tities list. 5.Set the Thermal C ontact Resistanc e. 6.Define the discr ete phase b oundar y condition f or the p orous jump (f or discr ete phase c alcula tions). 7.If you ha ve enabled the solar load mo del, define the Solar B oundar y Conditions for the p orous jump . These settings allo w you t o define the b oundar y such tha t it ac ts as a semi-tr anspar ent sur face (with r e- spect to the solar r adia tion c alcula tion only), and ther efore allo ws a p ortion of the solar r adia tion t o pass through it. See Solar R ay Tracing (p.1554 ) for details . 7.3.21.1.1. Identifying the P orous Jump Z one Since the p orous jump mo del is a 1D simplific ation of the p orous media mo del, the p orous-jump zone must b e mo deled as the in terface between c ells, rather than a c ell z one .Therefore the p orous- jump z one is a t ype of in ternal fac e zone (wher e the fac es ar e line segmen ts in 2D or tr iangles/quad- rilaterals in 3D). If the p orous-jump z one is not iden tified as such b y default when y ou r ead in the mesh (tha t is, if it is iden tified as another t ype of in ternal fac e zone), you c an r ight-click the z one in the tr ee and use the Type sub-menu t o change it t o a porous-jump zone (f or mor e details , see Changing C ell and B oundar y Zone Types (p.837)). After the z one has b een changed t o a p orous jump , you c an op en the Porous J ump D ialog Box (p.3518 ) (as descr ibed in Setting C ell Z one and B oundar y Conditions (p.839)) and sp ecify the p orous jump paramet ers list ed ab ove. 7.3.21.1.2. Defining D iscr ete Phase B oundar y Conditions for the P orous Jump If you ar e mo deling a discr ete phase of par ticles , you c an set the fa te of par ticle tr ajec tories a t the porous jump . See Setting B oundar y Conditions f or the D iscrete Phase (p.1985 ) for details . 7.3.21.2. Postpr ocessing for the P orous Jump Postpr ocessing suggestions f or a pr oblem tha t includes a p orous jump ar e the same as f or p orous media pr oblems . See Postpr ocessing f or P orous M edia (p.898). 7.4. Editing M ultiple B oundar y Conditions a t Onc e You c an edit multiple r elated b oundar ies (z ones of the same t ype) at the same time t o simplify the setup pr ocess f or ANSY S Fluen t cases . Using the Multi E dit dialo g box, you c an edit or apply selec ted settings only , to a set of b oundar ies without op ening multiple diff erent dialo g boxes.The dialo g box includes c olor ed ic ons t o indic ate which setting(s) will b e applied on the selec ted z ones . To acc ess the Multi E dit dialo g box: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1018Cell Z one and B oundar y Conditions1.Selec t the b oundar ies tha t you w ant to edit in the Outline View tr ee.You c an selec t multiple-b oundar ies b y holding Ctrl while y ou lef t-click. Alternatively, you c an selec t the b oundar ies tha t you w ant to edit in the Adjac ent Face Zones list of the Adjac ency Dialog Box (p.3780 ). Note One-sided (or e xternal) w alls c annot b e selec ted t ogether with c oupled (or in ternal) w alls for multi-editing . 2.Right-click the highligh ted b oundar ies and click Multi E dit.... While Figur e 7.73: The M ulti E dit Velocity Inlet D ialog Box (p.1020 ) is only f or p erforming a multi-edit of v elocity inlets , the multi-edit func tionalit y is a vailable f or the f ollowing b oundar y types: •exhaust fans •inlet v ents •intake fans •mass flo w inlets •mass flo w outlets •outflo ws •outlet v ents •pressur e far fields •pressur e inlets •pressur e outlets •velocity inlets •walls The setup f or the mult-edit v ersions of these dialo g boxes is the same as their non-multi-edit coun terparts.The multi-edit func tionalit y descr ibed in this sec tion is c onsist ent for all of the t ypes. 1019Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Editing M ultiple B oundar y Conditions a t Onc eFigur e 7.73: The M ulti E dit Velocity Inlet D ialo g Box The c olor ed ic ons within the Multi E dit dialo g box indic ate the sta tes of the v arious fields: • indic ates tha t the v alue of this setting v aries b etween the selec ted b oundar ies. • indic ates tha t the displa yed v alue will b e applied t o the selec ted b oundar ies when y ou click Apply . You c an click an ic on t o change its stat e, which w ould b e useful if y ou mo dify multiple settings , then realiz e you made a mistak e on one of them. To rectify the mistak e, you c an simpl y click to remo ve it, indic ating that the setting will not b e applied when y ou click Appl y. Note For an y value en try or selec tion tha t results in changes t o other fields , do not r ely on just reverting the "mast er field" (b y click ing the icon) t o revert the other aff ected fields . If a field has a gr een check mar k ( ) ne xt to it, assume tha t the sho wn v alue will b e applied on Apply , regar dless of if y ou r evert the initial change tha t led t o the other field changes . 3.The Zone List sho ws the selec ted b oundar ies wher e the fields denot ed with the icon will b e applied . You c an change which b oundar ies ar e highligh ted in the Zone List , allo wing y ou t o selec tively apply settings t o a subset of the b oundar ies in the list. The settings ar e applied t o the selec ted (highligh ted) zones when y ou click Apply . Note The "mast er zone" (sho wn in the Master Z one N ame field) c annot b e deselec ted in the Zone List . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1020Cell Z one and B oundar y Conditions7.5. Boundar y Acoustic Wave M odels The standar d boundar y conditions , when imp osed on the b oundar ies of an ar tificially tr uncated domain, result in the r eflec tion of the out going pr essur e waves. As a c onsequenc e, the in terior domain will contain spur ious w ave reflec tions . Many applic ations r equir e pr ecise c ontrol of the w ave reflec tions from the domain b oundar ies t o obtain accur ate flo w solutions . ANSY S Fluen t off ers se veral b oundar y wave mo dels tha t can b e used t o at the domain b oundar ies t o control these spur ious w ave reflec tions . The f ollowing b oundar y ac oustic w ave mo dels ar e available: •turb o-sp ecific non-r eflec ting b oundar y condition (NRBC) (densit y-based solv er only) •gener al NRBC (pr essur e-based and densit y-based solv ers) •imp edanc e boundar y condition (pr essur e-based solv er only) •transpar ent flo w forcing (pr essur e-based solv er only) In the densit y-based solv er, the NRBC mo dels ar e available f or flo ws using the c ompr essible ideal-gas law. In the pr essur e-based solv er, the gener al NRBC, imp edanc e, and tr ansien t flo w forcing mo dels a vailable for tr ansien t simula tions of c ompr essible flo ws (including the ideal-gas la w, real gas la w, species tr ansp ort, and c ompr essible mix ture mo dels). Information ab out the a vailable b oundar y ac oustic w ave mo dels is pr ovided in the f ollowing sec tions . 7.5.1. Turbo-Specific N on-R eflec ting B oundar y Conditions 7.5.2. Gener al Non-R eflec ting B oundar y Conditions 7.5.3. Imp edanc e Boundar y Conditions 7.5.4. Transpar ent Flow Forcing B oundar y Conditions 7.5.1. Turb o-Specific N on-Reflec ting B oundar y Conditions Information ab out turb o-sp ecific NRBCs is pr ovided in the f ollowing sec tions . 7.5.1.1. Overview 7.5.1.2. Limita tions 7.5.1.3. Theor y 7.5.1.4. Using Turbo-Specific N on-R eflec ting B oundar y Conditions 7.5.1.1. Overview The standar d pr essur e boundar y conditions f or c ompr essible flo w fix sp ecific flo w variables a t the boundar y (for e xample , static pr essur e at an outlet b oundar y). As a r esult , pressur e waves inciden t on the b oundar y will r eflec t in an unph ysical manner , leading t o lo cal er rors.The eff ects ar e mor e pronounc ed f or in ternal flo w pr oblems wher e boundar ies ar e usually close t o geometr y inside the domain, such as c ompr essor or turbine blade r ows. The turb o-sp ecific non-r eflec ting b oundar y conditions p ermit w aves to “pass ” through the b oundar ies without spur ious r eflec tions .The metho d used in ANSY S Fluen t is based on the F ourier tr ansf ormation of solution v ariables a t the non-r eflec ting b oundar y [41] (p.4007 ). Similar implemen tations ha ve been investiga ted b y other authors [80] (p.4009 )[107] (p.4010 ).The solution is r earranged as a sum of t erms corresponding t o diff erent frequencies , and their c ontributions ar e calcula ted indep enden tly.While 1021Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Acoustic Wave Modelsthe metho d w as or iginally designed f or axial turb omachiner y, it has b een e xtended f or use with r adial turb omachiner y. 7.5.1.2. Limitations Note the f ollowing limita tions of turb o-sp ecific NRBCs: •They are available only with the densit y-based solv er (e xplicit or implicit). •The cur rent implemen tation applies t o steady compr essible flo ws, with the densit y calcula ted using the ideal gas la w. •Inlet and outlet b oundar y conditions must b e pr essur e inlets and outlets only . Imp ortant Note tha t the pr essur e inlet b oundar ies must b e set t o the c ylindr ical coordina te flo w specific ation metho d when turb o-sp ecific NRBCs ar e used . •Quad-mapp ed (str uctured) sur face meshes must b e used f or inflo w and outflo w boundar ies in a 3D geo- metr y (tha t is, triangular or quad-pa ved sur face meshes ar e not allo wed). See Figur e 7.74: Mesh and P re- scribed B oundar y Conditions in a 3D A xial F low Problem (p.1023 ) and Figur e 7.75: Mesh and P rescr ibed Boundar y Conditions in a 3D R adial F low Problem (p.1023 ) for e xamples . Imp ortant Note tha t you ma y use unstr uctured meshes in 2D geometr ies ( Figur e 7.76: Mesh and Prescr ibed B oundar y Conditions in a 2D C ase (p.1024 )), and an unstr uctured mesh ma y be used a way from the inlet and outlet b oundar ies in 3D geometr ies. •The turb o-sp ecific NRBC [41] (p.4007 ) has b een e xtended f or use on 3D geometr ies [107] (p.4010 ) by dec oup- ling the tangen tial flo w variations fr om the r adial v ariations .This appr oxima tion w orks b est f or geometr ies with a blade pit ch tha t is small c ompar ed t o the r adius of the geometr y. •Reverse flo w on the inflo w and outflo w boundar ies ar e not allo wed. If str ong r everse flo w is pr esen t, then you should c onsider using the G ener al NRBCs inst ead. •NRBCs ar e not c ompa tible with sp ecies tr ansp ort mo dels .They are mainly used t o solv e ideal-gas single- species flo w. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1022Cell Z one and B oundar y ConditionsFigur e 7.74: Mesh and P rescr ibed B oundar y Conditions in a 3D A xial F low P roblem Figur e 7.75: Mesh and P rescr ibed B oundar y Conditions in a 3D R adial F low P roblem 1023Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Acoustic Wave ModelsFigur e 7.76: Mesh and P rescr ibed B oundar y Conditions in a 2D C ase 7.5.1.3. Theor y Turbo-sp ecific NRBCs ar e based on F ourier dec omp osition of solutions t o the linear ized E uler equa tions . The solution a t the inlet and outlet b oundar ies is cir cumf erentially dec omp osed in to Fourier mo des, with the 0th mo de r epresen ting the a verage b oundar y value (which is t o be imp osed as a user input), and higher har monics tha t are mo dified t o elimina te reflec tions [107] (p.4010 ). 7.5.1.3.1. Equations in C har acteristic Variable F orm In or der t o treat individual w aves, the linear ized E uler equa tions ar e transf ormed t o char acteristic variable ( ) form. If we first c onsider the 1D f orm of the linear ized E uler equa tions , it c an b e sho wn that the char acteristic v ariables are related t o the solution v ariables as f ollows: (7.146) wher e Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1024Cell Z one and B oundar y Conditions(7.147) wher e is the a verage ac oustic sp eed along a b oundar y zone , , , , , and represen t perturb- ations fr om a unif orm condition (f or e xample , , and so on). Note tha t the analy sis is p erformed using the c ylindr ical coordina te sy stem. All overlined (a veraged) flow field v ariables (f or e xample , , ) are in tended t o be averaged along the pit chwise dir ection. In quasi-3D appr oaches [41] (p.4007 )[80] (p.4009 )[107] (p.4010 ), a pr ocedur e is de velop ed t o det ermine the changes in the char acteristic v ariables , denot ed b y , at the b oundar ies such tha t waves will not r eflec t.These changes in char acteristic v ariables ar e det ermined as f ollows: (7.148) wher e (7.149) The changes t o the out going char acteristics — one char acteristic f or subsonic inflo w ( ), and f our char acteristics f or subsonic outflo w ( , , , ) — ar e det ermined fr om e xtrapolation of the flow field v ariables using Equa tion 7.148 (p.1025 ). The changes in the inc oming char acteristics — f our char acteristics f or subsonic inflo w ( , , , ), and one char acteristic f or subsonic outflo w ( ) — ar e split in to two comp onen ts: average change along the b oundar y ( ), and lo cal changes in the char acteristic v ariable due t o har monic variation along the b oundar y ( ).The inc oming char acteristics ar e ther efore giv en b y (7.150) (7.151) wher e on the inlet b oundar y or on the outlet b oundar y, and is the gr id inde x in the pit chwise dir ection including the p eriodic p oint onc e.The under-r elaxa tion fac tor has a default v alue of . Note tha t this metho d assumes a p eriodic solution in the pit chwise dir ection. The flo w is dec omp osed in to mean and cir cumf erential c omp onen ts using F ourier dec omp osition. The 0th F ourier mo de c orresponds t o the a verage cir cumf erential solution, and is tr eated acc ording to the standar d 1D char acteristic theor y.The r emaining par ts of the solution ar e descr ibed b y a sum of har monics , and tr eated as 2D non-r eflec ting b oundar y conditions [41] (p.4007 ). 1025Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Acoustic Wave Models7.5.1.3.2. Inlet B oundar y For subsonic inflo w, ther e is one out going char acteristic ( ) det ermined fr om Equa tion 7.148 (p.1025 ), and f our inc oming char acteristics ( , , , ) calcula ted using Equa tion 7.150 (p.1025 ).The average changes in the inc oming char acteristics ar e comput ed fr om the r equir emen t tha t the en tropy ( ), radial and tangen tial flo w angles ( and ), and stagna tion en thalp y ( ) are sp ecified . Note that in ANSY S Fluen t you c an sp ecify and at the inlet , from which and are easily obtained . This is equiv alen t to forcing the f ollowing f our r esiduals t o be zero: (7.152) (7.153) (7.154) (7.155) wher e (7.156) (7.157) The a verage char acteristic is then obtained fr om r esidual linear ization as f ollows (see also Fig- ure 7.77: Prescr ibed Inlet A ngles (p.1027 ) (7.158) wher e (7.159) (7.160) (7.161) and (7.162) (7.163) (7.164) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1026Cell Z one and B oundar y ConditionsFigur e 7.77: Prescr ibed Inlet A ngles wher e (7.165) (7.166) (7.167) (7.168) (7.169) (7.170) To addr ess the lo cal char acteristic changes a t each grid p oint along the inflo w b oundar y, the f ol- lowing r elations ar e de velop ed [41] (p.4007 )[107] (p.4010 ): (7.171) Note tha t the r elation f or the first and f ourth lo cal char acteristics f orce the lo cal en tropy and stagna- tion en thalp y to ma tch their a verage st eady-sta te values . The char acteristic v ariable is c omput ed fr om the in verse discr ete Fourier tr ansf orm of the sec ond char acteristic .The discr ete Fourier tr ansf orm of the sec ond char acteristic in tur n is r elated t o the discr ete Fourier tr ansf orm of the fif th char acteristic . Hence, the char acteristic v ariable is c omput ed along the pit ch as f ollows: 1027Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Acoustic Wave Models(7.172) The F ourier c oefficien ts are related t o a set of equidistan t distr ibut ed char acteristic v ariables by the f ollowing [80] (p.4009 ): (7.173) wher e (7.174) and (7.175) The set of equidistr ibut ed char acteristic v ariables is c omput ed fr om arbitr ary distr ibut ed by using a cubic spline f or in terpolation, wher e (7.176) For sup ersonic inflo w the user-pr escr ibed sta tic pr essur e ( ) along with t otal pr essur e ( ) and total t emp erature ( ) are sufficien t for det ermining the flo w condition a t the inlet. 7.5.1.3.3. Outlet B oundar y For subsonic outflo w, ther e ar e four out going char acteristics ( , , , and ) calcula ted using Equa tion 7.148 (p.1025 ), and one inc oming char acteristic ( ) det ermined fr om Equa tion 7.150 (p.1025 ). The a verage change in the inc oming fif th char acteristic is giv en b y (7.177) wher e is the cur rent averaged pr essur e at the e xit plane and is the desir able a verage e xit pressur e (this v alue is sp ecified b y you f or single-blade c alcula tions or obtained fr om the assigned profile f or mixing-plane c alcula tions). The lo cal changes ( ) are giv en b y (7.178) The char acteristic v ariable is c omput ed along the pit ch as f ollows: (7.179) The F ourier c oefficien ts are related t o two sets of equidistan tly distr ibut ed char acteristic v ariables ( and , respectively) and giv en b y the f ollowing [80] (p.4009 ): Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1028Cell Z one and B oundar y Conditions(7.180) wher e (7.181) (7.182) The t wo sets of equidistr ibut ed char acteristic v ariables ( and ) are comput ed fr om arbitr arily distr ibut ed and char acteristics b y using a cubic spline f or in terpolation, wher e (7.183) (7.184) For sup ersonic outflo w all flo w field v ariables ar e extrapolated fr om the in terior. 7.5.1.3.4. Up dat ed F low Variables Onc e the changes in the char acteristics ar e det ermined on the inflo w or outflo w b oundar ies, the changes in the flo w variables can b e obtained fr om Equa tion 7.148 (p.1025 ).Therefore, the v alues of the flo w variables a t the b oundar y fac es ar e as f ollows: (7.185) (7.186) (7.187) (7.188) (7.189) 7.5.1.4. Using Turb o-Sp ecific N on-R eflec ting B oundar y Conditions Imp ortant If you in tend t o use turb o-sp ecific NRBCs in c onjunc tion with the densit y-based implicit solv er, it is r ecommended tha t you first c onverge the solution b efore tur ning on turb o- specific NRBCs , then c onverge it again with turb o-sp ecific NRBCs tur ned on. If the solution is div erging , then y ou should lo wer the CFL numb er.These st eps ar e nec essar y because only appr oxima te flux Jac obians ar e used f or the pr essur e-inlet and pr essur e-outlet boundar ies when turb o-sp ecific NRBCs ar e ac tivated with the densit y-based implicit solv er. The pr ocedur e for using the turb o-sp ecific NRBCs is as f ollows: 1.Turn on the turb o-sp ecific NRBCs using the non-reflecting-bc text command: define → boundary-conditions → non-reflecting-bc → turbo-specific-nrbc → enable? 1029Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Acoustic Wave ModelsIf you ar e not sur e whether or not NRBCs ar e tur ned on, use the show-status text command . 2.Perform NRBC initializa tion using the initialize text command: define → boundary-conditions → non-reflecting-bc → turbo-specific-nrbc → initialize If the initializa tion is succ essful, a summar y pr intout of the domain e xtent will b e displa yed. If the initializa tion is not succ essful, an er ror message will b e displa yed indic ating the sour ce of the problem. The initializa tion will set up the pr essur e-inlet and pr essur e-outlet b oundar ies f or use with turb o-sp ecific NRBCs . Imp ortant Note tha t the pr essur e inlet b oundar ies must b e set t o the c ylindr ical coordina te flo w specific ation metho d when turb o-sp ecific NRBCs ar e used . 3.If nec essar y, mo dify the par amet ers in the set/ submenu: define → boundary-conditions → non-reflecting-bc → turbo-specific-nrbc → set under-relaxation allows you t o set the v alue of the under-r elaxa tion fac tor in Equa tion 7.150 (p.1025 ).The default value is . discretization allows you t o set the discr etiza tion scheme .The default is t o use higher-or der r econstr uction if available . verbosity allows you t o control the amoun t of inf ormation pr inted t o the c onsole dur ing an NRBC c alcula tion. •0 : silen t •1 : basic inf ormation (default) •2: detailed inf ormation (f or debugging pur poses only) 7.5.1.4.1. Using the NRBCs with the M ixing-P lane Mo del If you w ant to use the NRBCs with the mixing-plane mo del y ou must define the mixing plane in terfaces as pr essur e-outlet and pr essur e-inlet z one t ype pairs . Imp ortant Turbo-sp ecific NRBCs should not b e used with the mixing-plane mo del if r everse flo w is presen t acr oss the mixing-plane . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1030Cell Z one and B oundar y Conditions7.5.1.4.2. Using the NRBCs in P arallel ANSY S Fluent When the turb o-sp ecific NRBCs ar e used in c onjunc tion with the par allel solv er, all c ells in each boundar y zone , wher e NRBCs will b e applied , must b e lo cated or c ontained within a single par tition. You c an ensur e this b y manually par titioning the mesh (see Partitioning the M esh M anually and Balancing the L oad (p.3071 ) for mor e inf ormation). 7.5.2. Gener al N on-Reflec ting B oundar y Conditions Information ab out gener al NRBCs is pr ovided in the f ollowing sec tions . 7.5.2.1. Overview 7.5.2.2. Restrictions and Limita tions 7.5.2.3. Theor y 7.5.2.4. Using the G ener al Non-R eflec ting B oundar y Condition 7.5.2.1. Overview The gener al non-r eflec ting b oundar y conditions in ANSY S Fluen t are based on char acteristic w ave relations der ived fr om the E uler equa tions . In the densit y-based solv er, the non-r eflec ting b oundar y conditions ar e applied only on pr essur e-outlet b oundar y conditions . In the pr essur e-based solv er the y are applied on pr essur e-inlet , pressur e-outlet , velocity-inlet and mass-flux b oundar y conditions .To obtain the pr imitiv e flo w quan tities ( ), reformula ted E uler equa tions ar e solv ed on the boundar y of the domain in an algor ithm similar t o the flo w equa tions applied t o the in terior of the domain. Unlike the turb o-sp ecific NRBC, the gener al NRBC metho d is not r estricted b y geometr ic constr aints or mesh t ype. However, good cell sk ewness near the b oundar ies wher e the NRBCs c an b e applied for b etter convergenc e. 7.5.2.2. Restric tions and Limitations Note the f ollowing r estrictions and limita tions on the gener al NRBCs: •The gener al NRBC is not a vailable if the tar get mass flo w rate is ac tivated in the pr essur e-outlet dialo g box. •The gener al NRBC using the densit y-based solv er is a vailable only with c ompr essible flo w while using the ideal-gas la w. Imp ortant The gener al NRBC using the densit y-based solv er should not b e used with the w et st eam or real gas mo dels . •The gener al NRBCs using the densit y-based solv er ar e not c ompa tible with sp ecies tr ansp ort and mix ture fraction tr ansp ort mo dels (f or pr emix ed and par tially-pr emix ed mo dels). They are mainly used t o solv e ideal-gas single-c omp onen t flo w. •The gener al NRBCs using the pr essur e-based solv er ar e not c ompa tible with st eady-sta te cases or the E uler ian multiphase mo del. For VOF or mix ture multiphase c ases tha t involve compr essible gases or c ompr essible liquids , only pr essur e inlets and pr essur e outlets c an enable the non-r eflec ting 1031Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Acoustic Wave Modelsboundar y condition option. Note tha t some small r eflec tions ma y still o ccur fr om NRBC b oundar ies when sec ondar y-phase v olume fr actions ar e nonz ero at the b oundar ies. 7.5.2.3. Theor y Gener al NRBCs ar e der ived b y first r ecasting the E uler equa tions in an or thogonal c oordina te sy stem ( ) such tha t one of the c oordina tes, , is nor mal t o the b oundar y Figur e 7.78: The L ocal Or tho- gonal C oordina te System on to which E uler E qua tions ar e Recasted f or the G ener al NRBC M etho d (p.1033 ). The char acteristic analy sis [136] (p.4012 )[137] (p.4012 ) is then used t o mo dify t erms c orresponding t o waves pr opaga ting in the nor mal dir ection. When doing so , a sy stem of equa tions c an b e wr itten to descr ibe the w ave pr opaga tion as f ollows: (7.190) Where , and and , and are the v elocity comp onen ts in the c oordina te system ( , , ).The equa tions ab ove ar e solv ed on non-r eflec ting b oundar ies, along with the in terior governing flo w equa tions , using similar time st epping algor ithms t o obtain the v alues of the pr imitiv e flow variables ( ). Imp ortant Note tha t a tr ansf ormation b etween the lo cal or thogonal c oordina te sy stem ( , , ) and the global C artesian sy stem (X, Y, Z) must b e defined on each fac e on the b oundar y to obtain the v elocity comp onen ts ( , , ) in a global C artesian sy stem. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1032Cell Z one and B oundar y ConditionsFigur e 7.78: The L ocal Or tho gonal C oordina te System on to which E uler E qua tions ar e Rec asted for the G ener al NRBC M etho d The terms in the tr ansf ormed E uler equa tions c ontain the out going and inc oming char acteristic wave amplitudes , , and ar e defined as f ollows: (7.191) From char acteristic analy ses, the w ave amplitudes , , are giv en b y: (7.192) 1033Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Acoustic Wave ModelsThe out going and inc oming char acteristic w aves ar e asso ciated with the char acteristic v elocities of the sy stem (i.e eigen values), , as seen in Figur e 7.79: Waves L eaving and En tering a B oundar y Face on Inflo w and Outflo w Boundar ies.The Wave Amplitudes ar e Shown with the A ssociated E igen values for a Subsonic F low C ondition (p.1034 ).These eigen values ar e giv en b y: (7.193) Figur e 7.79: Waves L eaving and E ntering a B oundar y Face on Inflo w and Outflo w B oundar ies. The Wave Amplitudes ar e Shown with the A ssociated E igen values f or a S ubsonic F low C ondition For subsonic flo w lea ving a b oundar y, four w aves lea ve the domain (asso ciated with p ositiv e eigen- values , , , and ) and one en ters the domain (asso ciated with nega tive eigen value ). For subsonic flo w en tering a b oundar y, four w aves en ter the domain (asso ciated with the nega tive eigen- values , , , ) and one lea ves the domain (asso ciated with a p ositiv e eigen value ). To solv e Equa tion 7.190 (p.1032 ) on a b oundar y, the amplitude of the inc oming and out going w aves must b e first det ermined .The amplitude of out going w aves ar e comput ed fr om Equa tion 7.192 (p.1033 ) by using e xtrapolated v alues of flo w der ivatives , , , , and from inside the domain. The amplitude of the inc oming w aves ar e comput ed as f ollows.The amplitude of w aves , , for tangen tial velocity comp onen ts, is set t o zero.The amplitude of the inc oming pr essur e and en tropy waves ar e comput ed fr om the Linear R elaxa tion M etho d (LRM) of P oinsot [93] (p.4010 )[94] (p.4010 ).The LRM metho d sets the v alue of the inc oming w ave amplitude t o be pr oportional t o the diff erences b etween the lo cal pr imitiv e variable on a b oundar y fac e and the imp osed b oundar y value .The e xpression f or the amplitudes dep ends on the b oundar y type as sho wn b elow: 1.Pressur e Outlet (7.194) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1034Cell Z one and B oundar y Conditionswher e is the imp osed pr essur e at the e xit b oundar y, is the r elaxa tion fac tor, and is the local pr essur e value a t the b oundar y. In gener al, the desir able a verage pr essur e on a non-r eflec ting b oundar y can b e either r elax ed t o- ward a pr essur e value a t infinit y or enf orced t o be equiv alen t to some desir ed pr essur e at the e xit of the b oundar y. In the c ase of a backflo w, the pr essur e-based solv er has t wo options f or sp ecifying pr essur e at the b oundar y; static pr essur e or t otal pr essur e. If the sta tic pr essur e option is selec ted, the pr essur e at infinit y is equal t o the pr essur e defined in the b oundar y dialo g box. If the t otal pr essur e option is selec ted, the pr essur e at infinit y is a t otal pr essur e tha t is c omput ed fr om the v alue in the dialo g box. For the densit y-based solv er, the t otal pr essur e option is used and no other options ar e available . If you w ant the a verage pr essur e at the b oundar y to relax t oward at infinit y (tha t is ), the suggest ed factor is giv en b y: (7.195) wher e is the ac oustic sp eed, is the domain siz e, is the maximum M ach numb er in the domain, and is the under-r elaxa tion fac tor (default v alue is 0.15). On the other hand , if the desir ed average pr essur e at the b oundar y is t o appr oach a sp ecific imp osed v alue a t the b oundar y, then the factor is giv en b y: (7.196) wher e the default v alue f or is 5.0 Imp ortant The desir ed a verage pr essur e option is only a vailable f or the densit y-based solv er. 2.Pressur e Inlet : (7.197) wher e the imp osed pr essur e, , and densit y, , are comput ed fr om the sp ecified t otal pressur e and t otal t emp erature. 3.Mass F lux B oundar y: (7.198) wher e the imp osed e xit v elocity and densit y are comput ed fr om sp ecific mass flux and t otal temp erature. 4.Velocity Inlet : (7.199) 1035Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Acoustic Wave Modelswher e the imp osed v elocity, , is sp ecified a t the b oundar y and the imp osed densit y is comput ed fr om the sp ecified b oundar y temp erature and e xtrapolated pr essur e. 7.5.2.4. Using the G ener al N on-R eflec ting B oundar y Condition The gener al N on-R eflec ting B oundar y Condition is a vailable f or use in the Pressur e Outlet dialo g box when either the densit y-based (with ideal gas la w) or pr essur e-based solv ers ar e ac tivated t o solv e for c ompr essible flo ws.The gener al N on-R eflec ting B oundar y Condition is a vailable f or use in the Pressur e Inlet ,Mass-F low Inlet , and Velocity Inlet dialo g boxes when the pr essur e-based solv er is ac tivated t o solv e for c ompr essible flo ws. The e xample b elow sho ws you ho w to enable the gener al N on-R eflec ting B oundar y Condition in the Pressur e Outlet dialo g box.You w ould f ollow similar st eps f or the other b oundar y condition t ypes men tioned ab ove. 1. Selec t pressur e-outlet from the Boundar y Conditions task page and click the Edit... butt on. 2. In the Pressur e Outlet dialo g box, cho ose Non Reflec ting under Acoustic Wave M odel. Figur e 7.80: The P ressur e Outlet D ialo g Box With the N on-Reflec ting B oundar y Enabled 3. For the densit y-based solv er, selec t one of the t wo Exit P ressur e Specific ation options: Pressur e at Infinit y or Average B oundar y Pressur e.The pr essur e-based solv er uses the Pressur e at Infinit y option and the Exit P ressur e Specific ation drop-do wn list is not a vailable . a. The Pressur e at Infinit y boundar y is t ypic ally used in unst eady calcula tions or when the e xit pressur e value is imp osed a t infinit y.The b oundar y is designed so tha t the pr essur e at the boundar y relax es toward the imp osed pr essur e at infinit y.The sp eed a t which this r elaxa tion tak es plac e is c ontrolled b y the par amet er,sigma , which c an b e adjust ed in the TUI: define → boundary-conditions → non-reflecting-bc → general-nrbc → set Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1036Cell Z one and B oundar y ConditionsIn the set/ submenu , you c an set the sigma value .The default v alue f or sigma is 0.15. b.The Average B oundar y Pressur e specific ation is usually used in st eady-sta te calcula tions when you w ant to force the a verage pr essur e on the b oundar y to appr oach the e xit pr essur e value .The matching of a verage e xit pr essur e to the imp osed a verage pr essur e is c ontrolled b y the par amet er sigma2 which c an b e adjust ed in the TUI: define → boundary-conditions → non-reflecting-bc → general-nrbc → set In the set/ submenu , you c an set the sigma2 value .The default v alue f or sigma2 is 5.0. Imp ortant There is no guar antee tha t the sigma2 value of 5.0 will f orce the a verage b oundar y pressur e to ma tch the sp ecified e xit pr essur e in all flo w situa tions . In the c ase wher e the desir ed a verage b oundar y pr essur e has not b een achie ved, you c an in tervene t o adjust the sigma2 value so tha t the desir ed a verage pr essur e on the b oundar y is appr oached . 4. For the pr essur e-based solv er, you c an selec t one of t wo Backflo w P ressur e Specific ation options: Static P ressur e or Total P ressur e. For the densit y-based solv er, the Backflo w P ressur e Specific ation is not sho wn and the Total P ressur e option is used b y default. Note tha t backflo w is not allo wed f or pressur e inlets , mass-flo w inlets , or v elocity inlets . Imp ortant For the pr essur e-based solv er, you should cho ose Direction Vector or From N eigh- boring C ell as the Backflo w D irection S pecific ation M etho d if the flo w is tangen tial to the b oundar y.You should not selec t the Normal t o the B oundar y option f or Backflo w D irection S pecific ation M etho d in this c ase b ecause the fac e velocity comp onen ts for this c ase will b e comput ed fr om flux as z ero dur ing initializa tion. This initializa tion will c ause the solv er convergenc e to fail. Usually , the solv er can op erate at higher CFL v alues without the NRBCs b eing tur ned on. Therefore, the b est pr actice is t o first achie ve a go od stable solution (not nec essar ily c onverged) b efore ac tivating the non-r eflec ting b oundar y condition. In man y flo w situa tions , the CFL v alue must b e reduc ed fr om the nor mal op eration t o keep the solution stable .This is par ticular ly tr ue with the densit y-based im- plicit solv er sinc e the b oundar y up date is done in an e xplicit manner . A typic al CFL v alue in the densit y-based implicit solv er, with the NRBC ac tivated, is 2.0 and 4.0 in the pr essur e-based solv er. 7.5.3. Imp edanc e Boundar y Conditions The imp edanc e boundar y condition (IBC) lies in b etween a tr aditional r eflec tive boundar y condition and a fully non-r eflec tive boundar y condition. It provides the abilit y to sp ecify a par tial r eflec tion in the r ange fr om full-r eflec tion t o no-r eflec tion. Imp edanc e is a c omple x value; it is the r eflec tion tha t changes the amplitude and the phase of the inc oming w ave.The use of imp edanc e boundar y conditions comes in c ases wher e the flo w in the simula tion is highly influenc ed b y reflec ted w aves fr om objec ts outside the c omputa tional domain. In such c ases the ac oustic w ave in teraction fr om the lar ger domain can b e mo deled in the smaller domain thr ough the use of imp edanc e boundar y conditions . 1037Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Acoustic Wave Models7.5.3.1. Restric tions and Limitations The imp edanc e boundar y condition is a vailable only in the pr essur e-based solv er. It is inc ompa tible with st eady-sta te flo w, multiphase , or c ompr essible liquid mo dels ( compr essible-liquid metho d for densit y). 7.5.3.2. Theor y Imp edanc e sp ecifies an ac oustic r esistanc e in the fr equenc y domain. It is a char acteristic of the properties of the media and sp ecific geometr y descr ibed b y a r atio of the pr essur e perturba tion t o the nor mal v elocity perturba tion a t the b oundar y Blackst ock [[11] (p.4005 )]. (7.200) wher e ap ostr ophe denot es ac oustic p erturba tion and ha t denot es quan tity in the fr equenc y domain. Fluen t is a time domain solv er. It cannot use the imp edanc e from the fr equenc y domain dir ectly.The above expression and all its v ariables ha ve to be converted t o the time domain. After the c onversion the r elation b etween pr essur e and nor mal v elocity perturba tions is e xpressed thr ough a c onvolution integral. (7.201) If imp edanc e, , is unb ounded in the time domain, then admittanc e is used (admittanc e is the inverse of imp edanc e). Fluen t uses the r eflec tion c oefficien t inst ead of imp edanc e/admittanc e, to unif ormly tr eat unb ounded c ases F ung [ [36] (p.4006 )].The r eflec tion c oefficien t is a r atio b etween r e- flected and inc oming w ave amplitudes a t the b oundar y. It is e xpressed thr ough the imp edanc e as: (7.202) Using a r eflec tion c oefficien t, the r elation b etween pr essur e and nor mal v elocity perturba tion is: (7.203) The discr etized f orm of this e xpression is used in F luen t to connec t acoustic pr essur e and nor mal velocity.The c omput ed ac oustic p erturba tions ar e sup erimp osed on to the pr essur e and v elocity from non-r eflec ting b oundar y condition equa tions .The non-r eflec ting b oundar y condition equa tions pr ovide mean flo w values a t the b oundar y, which dr ive the flo w in the domain. The da ta for the r eflec tion c oefficien t are available in the fr equenc y domain. As such the y usually do not sa tisfy the c ausalit y and r ealit y conditions . Fluen t asks y ou t o pr ovide the r eflec tion c oefficien t data in the f orm of a sp ecial appr oxima tion. This appr oxima tion is based on the sy stem theor y, which ensur es tha t the r eflec tion c oefficien t in the time domain will sa tisfy the ab ove conditions F ung [[35] (p.4006 )].The r eflec tion c oefficien t is r epresen ted as a sum of z ero, first and sec ond or der sy stems . The z ero sy stem is descr ibed with a r eal v alue , the first or der sy stem is descr ibed with a r eal p ole, and the sec ond or der sy stem is descr ibed with a pair of c omple x conjuga te poles . Introducing a sy stem variable , the c omplet e appr oxima tion f or the r eflec tion c oefficien t is: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1038Cell Z one and B oundar y Conditions(7.204) wher e is a r eal t erm, is a numb er of r eal p oles , and are real p ole and its amplitude , is a numb er of c omple x conjuga te pole pairs , , are real and imaginar y par t of the c omple x conjuga te pole, and are real and imaginar y par t of the amplitude of the c omple x pole. To ob ey the c ausalit y and r ealit y conditions , real p ole , real and imaginar y par t of the c omple x conjuga te pole should b e positiv e.The passivit y condition r equir es tha t the absolut e value of z ero order t erm be less than 1. The ab ove restrictions ar e enf orced in the user in terface. In addition y ou should ensur e tha t the absolut e value of the r eflec tion c oefficien t comput ed b y this f ormula is less than 1. The imp edanc e da ta can b e obtained fr om measur emen ts or fr om an ac oustic solv er. Running these data thr ough a ma thema tics pack age will pr ovide an appr oxima tion in t erms of first and sec ond or der poles . 7.5.3.3. Using the Imp edanc e Boundar y Condition The e xample b elow sho ws you ho w to enable the imp edanc e boundar y condition (IBC) in the Pressur e Outlet dialo g box. Similar ly, you c an enable IBC in the Pressur e Inlet ,Velocity Inlet , and Mass-F low Inlet dialo g boxes for c ompr essible flo ws with the pr essur e-based solv er. 1. Selec t pressur e-outlet from the Boundar y Condition task page and click the Edit... butt on. 2. In the Pressur e Outlet dialo g box, cho ose Imp edanc e under Acoustic Wave M odel. The dialo g box will e xpand t o reveal Imp edanc e Paramet ers. 1039Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Acoustic Wave Models3. In Imp edanc e Paramet ers enter da ta for the r eflec tion c oefficien t acc ording t o the appr oxima tion formula ( Equa tion 7.204 (p.1039 )). a. Specify the Zero Or der Term, . b.Under Real P ole S eries, set the Numb er of Real P oles and f or each r eal p ole sp ecify the Pole, , and the Amplitude , . c.Under Comple x Pole S eries, set the Numb er of C omple x Poles and f or each c omple x pole pair , specify Pole Real , ,Pole Imaginar y, ,Amplitude Real , , and Amplitude Imaginar y, . Imp ortant If flo w is tangen tial t o the b oundar y, then sp ecify either From N eighb oring C ell or Direction Vector for Back flo w D irection S pecific ation M etho d. Do not selec t Normal to the b oundar y because this c omput es the fac e velocity comp onen ts fr om flux t o zero values dur ing initializa tion, which impairs solv er convergenc e. The IBC is implemen ted on t op of the non-r eflec tive boundar y condition. Note •The mean flo w in the domain should b e well established b efore enabling IBC. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1040Cell Z one and B oundar y Conditions•The c ell ac oustic C ourant (CFL) numb er should b e less than 1 in c ells adjac ent to the boundar y wher e you define an imp edanc e ac oustic b oundar y condition. (For the definition of the Cell A coustic C our ant Numb er, refer to Field F unction D efinitions (p.2959 )). •With the imp edanc e ac oustic b oundar y condition, you need t o tigh ten the c onvergenc e criteria for continuit y to 1e-4 in or der t o incr ease the numb er of c oupling it erations b etween the imp edanc e boundar y condition c alcula tion and the solv er at each time st ep. 7.5.4. Transpar ent Flow Forcing B oundar y Conditions It is of ten desir able in simula tions t o cut a domain do wn t o a smaller r egion t o mo del only a par t of the lar ger domain. The tr eatmen t at the b oundar ies cr eated when doing so should b e consist ent with a slic e thr ough the lar ger domain. That is, incoming tr ansien ts should b e allo wed t o en ter the c ompu- tational domain and out going tr ansien ts should lea ve the domain without r eflec tions . Artificial numer- ical reflec tions a t the b oundar ies c an signific antly aff ect the pr edic ted flo w, par ticular ly if the geometr y of the numer ical domain has E igen-fr equencies tha t ma tch the fr equencies of ph ysical w aves propaga ting thr ough the flo w. The tr anspar ent flo w forcing tr eatmen t provides the c apabilit y to mo del inc oming w aves while allo wing outgoing w aves to pass thr ough the b oundar ies without r eflec tion. It is a vailable in tr ansien t simula tions of c ompr essible flo w using the pr essur e-based solv er and c an b e applied f or v elocity inlets , mass-flo w inlets , pressur e inlets , and pr essur e outlets . 7.5.4.1. Restric tions and Limitations The tr anspar ent flo w forcing c ondition is a vailable only in the pr essur e-based solv er and it is inc om- patible with st eady-sta te flo w, multiphase , and c ompr essible liquid mo dels (those using the c ompr ess- ible-liquid metho d for densit y). 7.5.4.2. Theor y The tr anspar ent flo w forcing b oundar y condition is implemen ted on t op of the non-r eflec ting boundar y condition. The non-r eflec ting par t of the b oundar y condition dr ives the mean flo w.The transien t flo w at the b oundar y is split in to two waves [57] (p.4008 ): incoming w ave, , and outgoing w ave, . In the ac oustic limit , the in tensities of the w aves ar e expressed thr ough pressur e and nor mal v elocity perturba tions as: wher e is the sp ecific imp edanc e of the mean flo w with densit y, , and sp eed of sound , .The outgoing w ave in tensit y, , is c omput ed in ternally while the inc oming w ave in tensit y, , is user-sp ecified thr ough a user-defined pr ofile . 1041Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Acoustic Wave Models7.5.4.3. Using the Transpar ent F low F orcing B oundar y Condition The tr anspar ent flo w forcing ( TFF) b oundar y condition is a vailable a t velocity inlets , mass-flo w inlets , pressur e inlets , and pr essur e outlets when simula ting tr ansien t compr essible flo w using the pr essur e- based solv er.The st eps f or using the tr anspar ent flo w forcing b oundar y condition ar e as f ollows: 1. Create a pr ofile f or the inc oming w ave intensit y on the b oundar y.The pr ofile c an b e created either as a pr ofile file as descr ibed in Profiles (p.1051 ) or using the DEFINE_PROFILE macr o as descr ibed in Fluen t Customiza tion M anual . In the pr ofile definition, you will sp ecify the w ave intensit y as a func tion of p osition and time . For the inc oming w ave, the pr essur e and nor mal v elocity perturba tions sa tisfy the r elation: Using this r elation the inc oming w ave in tensit y at the b oundar y can b e comput ed fr om an y of the flo w p erturba tion quan tities . •from ac oustic pr essur e, •from ac oustic v elocity, •from ac oustic mass flux, wher e is the sp eed of sound and is the ac oustic imp edanc e. 2. Open the b oundar y condition settings dialo g box for the b oundar y zone of in terest ( Setting C ell Z one and B oundar y Conditions (p.839)). 3. On the Momen tum tab , selec t Transpar ent Flow Forcing under Acoustic Wave M odel. 4. Under Transpar ent Flow Forcing P aramet ers, selec t your pr ofile fr om the dr op-do wn list ne xt to In- coming Wave. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1042Cell Z one and B oundar y ConditionsImp ortant •If flo w is tangen tial t o the b oundar y, then sp ecify either From N eighb oring C ell or Direction Vector for Back flo w D irection S pecific ation M etho d. Do not selec t Normal t o the b oundar y because this c omput es the fac e velocity comp onen ts fr om flux t o zero values dur ing initializa- tion, which impairs solv er convergenc e. •The TFF c ondition is implemen ted on t op of the non-r eflec tive boundar y condition. Choose a time st ep tha t will not mak e the CFL numb er exceed a v alue of 1 in the c ells adjac ent to the TFF b oundar y. •The mean flo w in the domain should b e well established b efore enabling TFF. 7.6. User-D efined F an M odel The user-defined fan mo del in ANSY S Fluen t allo ws you t o periodically r egener ate a pr ofile file tha t can be used t o sp ecify the char acteristics of a fan, including pr essur e jump acr oss the fan, and r adial and swir ling c omp onen ts of v elocity gener ated b y the fan. For e xample , consider the c alcula tion of the pr essur e jump acr oss the fan. You c an, through the standar d in terface, input a c onstan t for the pr essur e jump , specify a p olynomial tha t descr ibes the pressur e jump as a func tion of axial v elocity thr ough the fan, or use a pr ofile file tha t descr ibes the 1043Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User-D efined F an M odelpressur e jump as a func tion of the axial v elocity or lo cation a t the fan fac e. If you use a pr ofile file , the same pr ofile will b e used c onsist ently thr oughout the c ourse of the solution. Supp ose, however, tha t you w ant to change the pr ofile as the flo w field de velops .This w ould r equir e a p eriodic up date to the profile file itself , based up on some instr uctions tha t you supply .The user-defined fan mo del is designed to help y ou do this . To use this mo del, you need t o gener ate an e xecutable tha t reads a fan pr ofile file tha t is wr itten b y ANSY S Fluen t, and wr ites out a mo dified one , which ANSY S Fluen t will then r ead.The sour ce code f or this e xecutable c an b e wr itten in an y pr ogramming language (F ortran or C, for e xample). Your pr ogram will b e called and e xecut ed aut oma tically, acc ording t o inputs tha t you supply thr ough the standar d interface. Information ab out the user-defined fan mo del is pr ovided in the f ollowing sec tions . 7.6.1. Steps f or U sing the U ser-D efined F an M odel 7.6.2. Example of a U ser-D efined F an 7.6.1. Steps f or U sing the U ser-D efined F an M odel To mak e use of the user-defined fan mo del, follow the st eps b elow. 1.In your mo del, iden tify one or mor e interior fac es to represen t one or mor e fan z ones . Setup → Boundar y Conditions 2.Input the name of y our e xecutable and the instr uctions f or reading and wr iting pr ofile files in the User- Defined F an M odel D ialog Box (p.3947 ). User D efined → Model S pecific → Fan M odel... 3.Initializ e the flo w field and the pr ofile files . 4.Enter the fan par amet ers using the standar d Fan D ialog Box (p.3488 ) (op ened fr om the Boundar y Conditions Task P age (p.3479 )). 5.Perform the c alcula tion. 7.6.2. Example of a U ser-D efined F an Usage of the user-defined fan mo del is b est demonstr ated b y an e xample .With this in mind , consider the domain sho wn in Figur e 7.81: The Inlet , Fan, and P ressur e Outlet Z ones f or a C ircular F an Op erating in a C ylindr ical D omain (p.1045 ). An inlet supplies air a t 10 m/s t o a c ylindr ical region, 1.25 m long and 0.2 m in diamet er, surrounded b y a symmetr y boundar y. At the c enter of the flo w domain is a cir cular fan. A pr essur e outlet b oundar y is a t the do wnstr eam end . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1044Cell Z one and B oundar y ConditionsFigur e 7.81: The Inlet , Fan, and P ressur e Outlet Z ones f or a C ircular F an Op erating in a C ylindr ical Domain Solving this pr oblem with the user-defined fan mo del will c ause ANSY S Fluen t to periodically wr ite out a r adial pr ofile file with the cur rent solution v ariables a t the fan fac e.These v ariables (sta tic pr essur e, pressur e jump , axial, radial, and swir ling (tangen tial) v elocity comp onen ts) will r epresen t averaged quan tities o ver annular sec tions of the fan. The siz es of the annular r egions ar e det ermined b y the siz e of the fan and the numb er of r adial p oints to be used in the pr ofiles . Onc e the pr ofile file is wr itten, ANSY S Fluen t will in voke an e xecutable , which will p erform the f ollowing tasks: 1.Read the pr ofile file c ontaining the cur rent flo w conditions a t the fan. 2.Perform a c alcula tion t o comput e new v alues f or the pr essur e jump , radial v elocity, and swir l velocity for the fan. 3.Write a new pr ofile file tha t contains the r esults of these c alcula tions . ANSY S Fluen t will then r ead the new pr ofile file and c ontinue with the c alcula tion. 7.6.2.1. Setting the User -Defined F an P aramet ers Specific ation of the par amet ers f or the user-defined fan b egins in the User-D efined F an M odel D ialog Box (p.3947 ) (Figur e 7.82: The U ser-D efined F an M odel D ialog Box (p.1046 )). User D efined → Model S pecific → Fan M odel... 1045Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User-D efined F an M odelFigur e 7.82: The U ser-D efined F an M odel D ialo g Box In this dialo g box, you c an selec t the fan z one(s) on which y our e xecutable will op erate under Fan Zones . In this e xample , ther e is only one fan, fan-8 . If you ha ve multiple fan z ones in a simula tion, for which y ou ha ve diff erent profile sp ecific ations , you c an selec t them all a t this p oint.Your e xecutable will b e able t o diff erentiate between the fan z ones b ecause the z one ID f or each fan is included in the solution pr ofile file .The e xecutable will b e invoked onc e for each z one , and separ ate pr ofile files will b e wr itten f or each. The e xecutable file will b e called on t o up date the pr ofile file p eriodically, based on the input f or the Iteration U pdate In terval. An input of 10, as sho wn in the dialo g box, means tha t the fan e xecutable in this e xample will ac t every 10 it erations t o mo dify the pr ofile file . The numb er of p oints in the pr ofile file t o be wr itten b y ANSY S Fluen t is en tered under Output P rofile Points.This pr ofile file c an ha ve the same or a diff erent numb er of p oints as the one tha t is wr itten by the e xternal e xecutable . Finally , the name of the e xecutable should b e en tered under External C ommand N ame . In the cur rent example , the name of the e xecutable is fan-model . Imp ortant If the e xecutable is not lo cated in y our w orking dir ectory, then y ou must t ype the c omplet e path to the e xecutable . 7.6.2.2. Sample User -Defined F an P rogram The e xecutable file will b e built fr om the F ortran pr ogram,fantest.f , which is sho wn b elow. c c This program is invoked at intervals by ANSYS Fluent to c read a profile-format file that contains radially Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1046Cell Z one and B oundar y Conditions c averaged data at a fan face, compute new pressure-jump c and swirl-velocity components, and write a new profile c file that will subsequently be read by ANSYS Fluent to c update the fan conditions. c c Usage: fantest input_profile output_profile c integer npmax parameter (npmax = 900) integer inp ! input: number of profile points integer iptype ! input: profile type (0=radial, 1=point) real ir(npmax) ! input: radial positions real ip(npmax) ! input: pressure real idp(npmax) ! input: pressure-jump real iva(npmax) ! input: axial velocity real ivr(npmax) ! input: radial velocity real ivt(npmax) ! input: tangential velocity character*80 zoneid integer rfanprof ! function to read a profile file integer status c status = rfanprof(npmax,zoneid,iptype, $ inp,ir,ip,idp,iva,ivr,ivt) if (status.ne.0) then write(*,*) ’error reading input profile file’ else do 10 i = 1, inp idp(i) = 200.0 - 10.0*iva(i) ivt(i) = 20.0*ir(i) ivr(i) = 0.0 10 continue call wfanprof(6,zoneid,iptype,inp,ir,idp,ivr,ivt) endif stop end After the v ariable declar ations , which ha ve commen ts on the r ight, the subr outine rfanprof is called t o read the pr ofile file , and pass the cur rent values of the r elevant variables (as defined in the declar ation list) t o fantest . A lo op is done on the numb er of p oints in the pr ofile t o comput e new values f or: •The pr essur e jump acr oss the fan, idp , which in this e xample is a func tion of the axial v elocity,iva . •The swir ling or tangen tial v elocity,ivt , which in this e xample is pr oportional t o the r adial p osition,ir. •The r adial v elocity,ivr , which in this e xample is set t o zero. After the lo op, a new pr ofile is wr itten b y the subr outine wfanprof , sho wn b elow. (For mor e inf orm- ation on pr ofile file f ormats, see Profile F ile F ormats (p.1052 ).) subroutine wfanprof(unit,zoneid,ptype,n,r,dp,vr,vt) c c writes an ANSYS Fluent profile file for input by the c user fan model c integer unit ! output unit number character*80 zoneid integer ptype ! profile type (0=radial, 1=point) integer n ! number of points real r(n) ! radial position real dp(n) ! pressure jump real vr(n) ! radial velocity real vt(n) ! tangential velocity character*6 typenam if (ptype.eq.0) then typenam = ’radial’ 1047Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User-D efined F an M odel else typenam = ’point’ endif write(unit,*) ’((’, zoneid(1:index(zoneid,’\0’)-1), ’ ’, $ typenam, n, ’)’ write(unit,*) ’(r’ write(unit,100) r write(unit,*) ’)’ write(unit,*) ’(pressure-jump’ write(unit,100) dp write(unit,*) ’)’ write(unit,*) ’(radial-velocity’ write(unit,100) vr write(unit,*) ’)’ write(unit,*) ’(tangential-velocity’ write(unit,100) vt write(unit,*) ’)’ 100 format(5(e15.8,1x)) return end This subr outine will wr ite a pr ofile file in either r adial or p oint format, based on y our input f or the integer ptype . (See Profiles (p.1051 ) for mor e details on the t ypes of pr ofile files tha t are available .) The names tha t you use f or the v arious pr ofiles ar e arbitr ary. Onc e you ha ve initializ ed the pr ofile files , the names y ou use in wfanprof will app ear as pr ofile names in the Fan D ialog Box (p.3488 ). 7.6.2.3. Initializing the F low F ield and P rofile F iles The ne xt step in the setup of the user-defined fan is t o initializ e (cr eate) the pr ofile files tha t will b e used .To do this , first initializ e the flo w field with the Solution Initializa tion Task P age (p.3620 ) (using the v elocity inlet c onditions , for e xample), and then t ype the c ommand (update-user-fans) in the c onsole windo w. (The par entheses ar e par t of the c ommand , and must b e typed in.) This will cr eate the pr ofile names tha t are giv en in the subr outine wfanprof . 7.6.2.4. Selec ting the P rofiles Onc e the pr ofile names ha ve been established , you will need t o visit the Fan D ialog Box (p.3488 ) (Fig- ure 7.83: The F an D ialog Box (p.1049 )) to complet e the pr oblem setup . (See Fan B oundar y Condi- tions (p.1002 ) for gener al inf ormation on using the Fan dialo g box.) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1048Cell Z one and B oundar y ConditionsFigur e 7.83: The F an D ialo g Box At this time , the Fan A xis,Fan Or igin , and Fan Hub R adius can b e en tered, along with the choic e of pr ofiles f or the c alcula tion of pr essur e jump , tangen tial v elocity, and r adial v elocity.With the pr ofile options enabled , you c an selec t the names of the pr ofiles fr om the dr op-do wn lists . In the dialo g box above, the selec ted pr ofiles ar e named fan_8_pr essur e_jump ,fan_8_tangen tial_v elocity, and fan_8_r adial_v elocity, corresponding t o the names tha t were used in the subr outine wfanprof . 7.6.2.5. Performing the C alculation The solution is no w ready to run. As it b egins t o converge, the r eport in the c onsole windo w sho ws that the pr ofile files ar e being wr itten and r ead e very 10 it erations: iter continuity x-velocity y-velocity z-velocity k ! 1 residual normalization factors changed (continuity 1 1.0000e+00 1.0000e+00 1.0000e+00 1.0000e+00 1.0000e+00 ! 2 residual normalization factors changed (continuity 2 1.0000e+00 1.0000e+00 1.0000e+00 1.0000e+00 9.4933e-01 3 6.8870e-01 7.2663e-01 7.3802e-01 7.5822e-01 6.1033e-01 . . . . . . . . . . . . . . . . . . 9 2.1779e-01 9.8139e-02 3.0497e-01 2.9609e-01 2.8612e-01 Writing "fan-8-out.prof"... Done. Reading "fan-8-in.prof"... Reading profile file... 10 "fan-8" radial-profile points, r, pressure-jump, radial-velocity, tangential-velocity. Done. 10 1.7612e-01 7.4618e-02 2.5194e-01 2.4538e-01 2.4569e-01 11 1.6895e-01 8.3699e-02 2.0316e-01 2.0280e-01 2.1169e-01 . . . . . . . . . . . . . . . . . . The file fan-8-out.prof is wr itten out b y ANSY S Fluen t and r ead b y the e xecutable fantest . It contains v alues f or pr essur e, pressur e jump , axial v elocity, radial v elocity, and tangen tial v elocity at 20 r adial lo cations a t the sit e of the fan. The file fan-8-in.prof is gener ated b y fantest and contains up dated v alues f or pr essur e jump and r adial and tangen tial v elocity only . It is ther efore a 1049Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User-D efined F an M odelsmaller file than fan-8-out.prof .The pr efix f or these files tak es its name fr om the fan z one with which the pr ofiles ar e asso ciated. An example of the pr ofile file fan-8-in.prof is sho wn b elow. This r epresen ts the last pr ofile file t o be wr itten b y fantest dur ing the c onvergenc e hist ory. ((fan-8 radial 10) (r 0.24295786E-01 0.33130988E-01 0.41966137E-01 0.50801374E-01 0.59636571E-01 0.68471842E-01 0.77307090E-01 0.86142287E-01 0.94963484E-01 0.95353782E-01 ) (pressure-jump 0.10182057E+03 0.98394081E+02 0.97748657E+02 0.97787750E+02 0.97905228E+02 0.98020668E+02 0.98138817E+02 0.98264198E+02 0.98469681E+02 0.98478783E+02 ) (radial-velocity 0.00000000E+00 0.00000000E+00 0.00000000E+00 0.00000000E+00 0.00000000E+00 0.00000000E+00 0.00000000E+00 0.00000000E+00 0.00000000E+00 0.00000000E+00 ) (tangential-velocity 0.48591572E+00 0.66261977E+00 0.83932275E+00 0.10160275E+01 0.11927314E+01 0.13694369E+01 0.15461419E+01 0.17228458E+01 0.18992697E+01 0.19070756E+01 ) 7.6.2.6. Results A plot of the tr ansv erse v elocity comp onen ts at the sit e of the fan is sho wn in Figur e 7.84: Transv erse Velocities a t the S ite of the F an (p.1050 ). As expected, ther e is no r adial c omp onen t, and the tangen tial (swir ling) c omp onen t incr eases with r adius . Figur e 7.84: Transv erse Velocities a t the S ite of the F an As a final check on the r esult , an X Y plot of the sta tic pr essur e as a func tion of position is sho wn (Figur e 7.85: Static P ressur e Jump A cross the F an (p.1051 )).This X Y plot is made on a line a t =0.05 m, or a t ab out half the r adius of the duc t. According t o the input file sho wn ab ove, the pr essur e jump at the sit e of the fan should b e appr oxima tely 97.8 P a/m. Examina tion of the figur e supp orts this finding . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1050Cell Z one and B oundar y ConditionsFigur e 7.85: Static P ressur e Jump A cross the F an 7.7. Profiles Profiles c an b e boundar y conditions , cell z one c onditions , and initial c onditions f or discr ete phases . ANSY S Fluen t provides a v ery fle xible pr ofile definition mechanism. This f eature allo ws you t o use e x- perimen tal da ta, data calcula ted b y an e xternal pr ogram, or da ta wr itten fr om a pr evious solution using the Write Profile D ialog Box (p.3478 ) (as descr ibed in Reading and Writing P rofile F iles (p.594)) as the boundar y condition f or a v ariable . Information ab out pr ofiles is pr esen ted in the f ollowing subsec tions: 7.7.1. Profile S pecific ation Types 7.7.2. Profile F ile F ormats 7.7.3. Using P rofiles 7.7.4. Reorienting P rofiles 7.7.5. Replic ating P rofiles 7.7.6. Defining Transien t Cell Z one and B oundar y Conditions 7.7.1. Profile S pecific ation Types The f ollowing is a list of the six t ypes of pr ofiles tha t can b e read in to ANSY S Fluen t, as w ell as inf orm- ation ab out the in terpolation metho d emplo yed b y ANSY S Fluen t for each t ype. •Point profiles ar e sp ecified b y an unor dered set of points: for 2D pr oblems or for 3D pr oblems , wher e . Profiles wr itten using the Write Profile dialo g box and pr ofiles of e xperimen tal data in r andom or der ar e examples of p oint profiles . ANSY S Fluen t will in terpolate the p oint cloud t o obtain v alues a t the b oundar y fac es.The default interpolation metho d for the unstr uctured p oint da ta is z eroth or der.That is, for each c ell fac e at the b oundar y, the solv er uses the v alue fr om the pr ofile file lo cated closest t o the c ell.Therefore, to get an accur ate sp ecific ation of an inlet pr ofile using the default in terpolation metho d, your 1051Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Profilesprofile file should c ontain a sufficien tly high p oint densit y. For inf ormation ab out other a vailable interpolation metho ds for p oint profiles , see Using P rofiles (p.1056 ). •Line pr ofiles ar e sp ecified f or 2D pr oblems b y an or dered set of points: , wher e . Zeroth- order in terpolation is p erformed b etween the p oints. An example of a line pr ofile is a pr ofile of da ta obtained from an e xternal pr ogram tha t calcula tes a b oundar y-layer pr ofile . •Mesh pr ofiles ar e sp ecified f or 3D pr oblems b y an by mesh of p oints: , wher e and . Zeroth-or der in terpolation is p erformed b etween the p oints. Examples of mesh pr ofiles ar e profiles of da ta fr om a str uctured mesh solution and e xperimen tal da ta in a r egular ar ray. •Radial pr ofiles ar e sp ecified f or 2D and 3D pr oblems b y an or dered set of points: , wher e . The da ta in a r adial pr ofile ar e a func tion of r adius only . Linear in terpolation is p erformed b etween the points, which must b e sor ted in asc ending or der of the field .The axis f or the c ylindr ical coordina te sy stem is det ermined as f ollows: –For 2D pr oblems , it is the -direction v ector thr ough (0,0). –For 2D axisymmetr ic pr oblems , it is the -direction v ector thr ough (0,0). –For 3D pr oblems in volving a swir ling fan, it is the fan axis defined in the Fan D ialog Box (p.3488 ) (unless you ar e using lo cal cylindr ical coordina tes a t the b oundar y, as descr ibed b elow). –For 3D pr oblems without a swir ling fan, it is the r otation axis of the adjac ent fluid z one , as defined in the Fluid D ialog Box (p.3457 ) (unless y ou ar e using lo cal cylindr ical coordina tes a t the b oundar y, as descr ibed below). –For 3D pr oblems in which y ou ar e using lo cal cylindr ical coordina tes to sp ecify c onditions a t the boundar y, it is the axis of the sp ecified lo cal coordina te sy stem. •Axial pr ofiles ar e sp ecified f or 3D pr oblems b y an or dered set of points: , wher e .The da ta in an axial pr ofile ar e a func tion of the axial dir ection. Linear in terpolation is p erformed b etween the p oints, which must b e sor ted in asc ending or der of the field . •Transien t profiles ar e sp ecified f or 2D and 3D pr ofiles b y an or dered set of points: . Linear in terpolations ar e done b etween the p oints which must b e sor ted in asc ending or der of the (time or cr ank angle) field . Examples of tr ansien t profiles ar e transien t cell z one and b oundar y conditions (see Defining Transien t Cell Z one and B oundar y Conditions (p.1066 )) and p oint properties f or par ticle injec tions (see Point Properties f or Transien t Injec tions (p.1984 )). 7.7.2. Profile F ile F ormats There ar e two pr ofile f ormat options: 7.7.2.1. Standar d Profiles 7.7.2.2. CSV P rofiles 7.7.2.1. Standar d Profiles The f ormat of the pr ofile files is fair ly simple .The file c an c ontain an arbitr ary numb er of pr ofiles . Each profile c onsists of a header tha t sp ecifies the pr ofile name , profile t ype (point ,line ,mesh ,radial , Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1052Cell Z one and B oundar y Conditionsor axial ), and numb er of defining p oints, and is f ollowed b y an arbitr ary numb er of named “fields ”. Some of these fields c ontain the c oordina te points and the r est c ontain b oundar y da ta. Imp ortant Keep pr ofile names t o 64 char acters or less . If the pr ofile name c ontains mor e than 64 char acters, Fluen t truncates the name t o the first 64 char acters. All quan tities , including c oordina te values , must b e sp ecified in SI units b ecause ANSY S Fluen t do es not p erform unit c onversion when r eading pr ofile files . Parentheses ar e used t o delimit pr ofiles and the fields within the pr ofiles . Any combina tion of tabs , spac es, and newlines c an b e used t o separ ate elemen ts. Imp ortant In the gener al format descr iption b elow,“ |” indic ates tha t you should input only one of the it ems separ ated b y |’s and “ ... ” indic ates a c ontinua tion of the list. ((profile1-name point|line|radial n) (field1-name a1 a2 ... an) (field2-name b1 b2 ... bn) . . . (fieldf-name f1 f2 ... fn)) ((profile2-name mesh m n) (field1-name a11 a12 ... a1n a21 a22 ... a2n . . . am1 am2 ... amn) . . . (fieldf-name f11 f12 ... f1n f21 f22 ... f2n . . . fm1 fm2 ... fmn)) Profile names must ha ve all lo wercase lett ers (f or e xample ,name ). Uppercase lett ers in pr ofile names are not acc eptable . Each pr ofile of t ype point ,line , and mesh must c ontain fields with names x, y, and , for 3D ,z. Each pr ofile of t ype radial must c ontain a field with name r. Each pr ofile of t ype axial must c ontain a field with name z.The r est of the names ar e arbitr ary, but must b e valid Scheme symb ols. For c ompa tibilit y with old-st yle pr ofile files , if the pr ofile t ype is missing ,point is assumed . 7.7.2.1.1. Example A typic al usage of a pr ofile file is t o sp ecify the pr ofile of the b oundar y layer a t an inlet. For a c om- pressible flo w calcula tion, this will b e done using pr ofiles of t otal pr essur e, , and . For an inc om- pressible flo w, it migh t be pr eferable t o sp ecify the inlet v alue of str eamwise v elocity, together with and . 1053Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.ProfilesBelow is an e xample of a pr ofile file tha t do es this: ((turb-prof point 8) (x 4.00000E+00 4.00000E+00 4.00000E+00 4.00000E+00 4.00000E+00 4.00000E+00 4.00000E+00 4.00000E+00 ) (y 1.06443E-03 3.19485E-03 5.33020E-03 7.47418E-03 2.90494E-01 3.31222E-01 3.84519E-01 4.57471E-01 ) (u 5.47866E+00 6.59870E+00 7.05731E+00 7.40079E+00 1.01674E+01 1.01656E+01 1.01637E+01 1.01616E+01 ) (tke 4.93228E-01 6.19247E-01 5.32680E-01 4.93642E-01 6.89414E-03 6.89666E-03 6.90015E-03 6.90478E-03 ) (eps 1.27713E+02 6.04399E+01 3.31187E+01 2.21535E+01 9.78365E-03 9.79056E-03 9.80001E-03 9.81265E-03 ) ) 7.7.2.2. CSV P rofiles CSV pr ofiles ar e compa tible with spr eadsheets and ar e available f or b oth r eading and wr iting in F luen t. Many pr ofile t ypes c an b e wr itten in CSV f ormat, including: •Radial •Axial •Point (X, Y, Z) •Transien t •Transien t-Periodic If wr iting a pr ofile using the Write Profile dialo g box, you c an sa ve the pr ofile in CSV f ormat by sa ving with a .csv extension. Formatting R ules: CSV pr ofiles must b e setup so the y can b e read and in terpreted c orrectly in F luen t: 1.The pr ofile file must c ontain the sec tion iden tifiers sho wn in Table 7.4: CSV P rofile S ection Iden tifiers (p.1054 ).These iden tifiers must b e used in the or der,[Name] then [Data] . Table 7.4: CSV P rofile S ection Iden tifiers Remar k Section Iden tifiers Next line should ha ve the pr ofile name .Note- if the pr ofile name has spac e char acters, the y will b e replac ed with '_' (spac e char acter is not allo wed).[Name] Data v alues b egin on the ne xt line . [Data] Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1054Cell Z one and B oundar y Conditions2.After the [Data] iden tifier y ou must lab el the t ype of da ta tha t you ar e pr oviding; refer to Table 7.5: Profile Types and the C orresponding R equir ed F ield Lab els (p.1055 ) for the c orrect lab els. If Fluen t do es not find one of the e xpected lab els, the pr ofile r ead will fail. Table 7.5: Profile Types and the C orresp onding Requir ed F ield L abels Requir ed F ield L abel Profile Type radius radial axis axial X,Y, Z point time , angle transien t time-p eriodic, angle-p eriodic transien t-periodic Imp ortant The f ollowing lab els ar e reser ved f or X-axis func tions:x,y,z,r,time , and angle . If your file c ontains fields lab eled with an y of these r eser ved names , then those fields will b e treated as X-axis func tions . For fields t o be consider ed as Y-axis func tions , you must use names tha t are not r eser ved f or X-axis func tions . 3.If ther e is an unsupp orted sec tion iden tifier , Fluen t ignor es the sec tion and lo oks f or the [Name] and [Data] sec tion iden tifiers . 4.Multiple pr ofiles ma y be included in a single file . Imp ortant •Only use c ommas as v alue separ ators. Space char acters should not b e used as the y will c onfuse external spr eadsheet applic ations . •Only SI v alues ar e supp orted. Quan tities c annot b e en tered with units . CSV P rofile F ile E xamples A file c ontaining one pr ofile: [Name] outlet [Data] x,y,z,x-velocity -0.00036448459,0.0068932362,3,0.5 0.0014999653,-0.0090896944,3,0.5 -0.0014358073,-0.0094413245,3, 0.5 0.0022810854,0.014916174,3,0.5 -0.0024638004,0.014873175,3,0.5 -0.0069573424,0.013364096,3,0.5 A file c ontaining t wo pr ofiles , the first one is spa tial (st eady-sta te) and the sec ond is tr ansien t. [Name] outlet 1055Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Profiles[Data] x,y,z,x-velocity -0.00036448459,0.0068932362,3,0.05 0.0014999653,-0.0090896944,3,0.05 [Name] transient-temperature [Data] time,temperature 1.1,300 1.2,350 1.3,400 7.7.3. Using P rofiles The pr ocedur e for using a pr ofile t o define a par ticular c ell z one or b oundar y condition is outlined below. 1.Create a file tha t contains the desir ed pr ofile , following the f ormat descr ibed in Profile F ile F ormats (p.1052 ). 2.Read the pr ofile using the Read ... butt on in the Profiles D ialog Box (p.3473 ) (Figur e 7.86: The P rofiles D ialog Box (p.1058 )) or the File/Read/P rofile ... ribbon tab it em. Setup → Cell Z one C onditions → Profiles ... Setup → Boundar y Conditions → Profiles ... File → Read → Profile ... Note tha t if y ou use the Profiles dialo g box to read a file , and a pr ofile in the file has the same name as an e xisting pr ofile , the old pr ofile will b e overwritten. 3.If it is a p oint profile , you c an cho ose the metho d of in terpolation using the Profiles dialo g box (Fig- ure 7.86: The P rofiles D ialog Box (p.1058 )): Setup → Cell Z one C onditions → Profiles ... Setup → Boundar y Conditions → Profiles ... Selec t the p oint profile in the Profile selec tion list. Then selec t one of the thr ee choic es in the In- terpolation M etho d list and click the Apply butt on.The thr ee choic es include: •Constan t This metho d is z eroth-or der in terpolation. For each c ell fac e at the b oundar y, the solv er uses the value fr om the pr ofile file lo cated closest t o the c ell.Therefore, the accur acy of the in terpolated profile will b e aff ected b y the densit y of the da ta p oints in y our pr ofile file .This is the default interpolation metho d for p oint profiles . •Inverse D istanc e Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1056Cell Z one and B oundar y ConditionsThis metho d assigns a v alue t o each c ell fac e at the b oundar y based on w eigh ted c ontributions from the v alues in the pr ofile file .The w eigh ting fac tor is in versely pr oportional t o the distanc e between the pr ofile p oint and the c ell fac e center. •Least S quar es This metho d assigns v alues t o the c ell fac es a t the b oundar y thr ough a first-or der in terpolation metho d tha t tries t o minimiz es the sum of the squar es of the off sets (r esiduals) b etween the profile da ta p oints and the c ell fac e centers.The least squar es solution is f ound using S ingular Value D ecomp osition (SVD). Note The Inverse D istanc e and Least S quar es profile in terpolation metho ds ar e not applic able when a pr ofile is a ttached t o cell z ones . For inf ormation ab out the in terpolation metho ds emplo yed f or other pr ofile t ypes (tha t is, line , mesh, radial, or axial pr ofiles), see Profile S pecific ation Types (p.1051 ). 4.You c an a ttach a pr ofile t o a r eference frame so tha t the pr ofile will r otate acc ording t o the r eference frame .This c an b e used t o mo del the clo cking eff ect of a r otor on a sta tor, for e xample . Under Referenc e Frames , selec t the r eference frame t o attach the chosen pr ofile t o. 5.In the b oundar y conditions dialo g boxes (f or e xample , the Velocity Inlet and Pressur e Inlet dialo g boxes), the fields defined in the pr ofile file (and those defined in an y other pr ofile file tha t you ha ve read in) will app ear in the dr op-do wn list t o the r ight of or b elow each par amet er for which pr ofile sp ecific ation is al- lowed.To use a par ticular pr ofile , selec t it in the appr opriate list. 6.Initializ e the solution t o interpolate the pr ofile . Note You c an use a pr ofile file or the DEFINE_PROFILE user-defined func tion t o sp ecify v olu- metr ic sour ce terms. If you sp ecify the sour ce terms with a pr ofile , you will not ha ve acc ess to the c entral coefficien t of the equa tions solv ed in or der t o linear ize the sour ce term.You will need t o use a user-defined func tion t o do this . For mor e inf ormation on UDFs , refer to the Fluen t Customiza tion M anual . 7.7.3.1. Check ing and D eleting P rofiles Each pr ofile file c ontains one or mor e pr ofiles , and each pr ofile has one or mor e fields defined in it. Onc e you ha ve read in a pr ofile file , you c an check which fields ar e defined in each pr ofile , and y ou can also delet e a par ticular pr ofile .These tasks ar e acc omplished in the Profiles D ialog Box (p.3473 ) (Figur e 7.86: The P rofiles D ialog Box (p.1058 )). Setup → Cell Z one C onditions → Profiles ... Setup → Boundar y Conditions → Profiles ... 1057Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.ProfilesFigur e 7.86: The P rofiles D ialo g Box To check which fields ar e defined in a par ticular pr ofile , selec t the pr ofile name in the Profile list. The available fields in tha t file will b e displa yed in the Fields list. In Figur e 7.86: The P rofiles D ialog Box (p.1058 ), the pr ofile fields fr om the pr ofile file of Example (p.1053 ) are sho wn. To delet e a pr ofile , selec t it in the Profile list and click the Delet e butt on.When a pr ofile is delet ed, all fields defined in it will b e remo ved fr om the Fields list. Imp ortant If you ar e deleting an e xisting pr ofile t o replac e it with a new pr ofile , use the f ollowing procedur e: 1. Delete the e xisting pr ofile . 2. Change the par amet ers defined b y the e xisting pr ofile t o Constan t. 3. Read the new pr ofile and apply as desir ed. 7.7.3.2. Viewing P rofile D ata The Plots task page options allo w you t o gener ate XY plots of da ta related t o pr ofiles .You c an plot the or iginal da ta p oints fr om the pr ofile file y ou ha ve read in to ANSY S Fluen t, or y ou c an plot the values assigned t o the c ell fac es on the b oundar y after the pr ofile file has b een in terpolated. See XY Plots of P rofiles (p.2870 ) for the st eps t o gener ate these plots . You ha ve the additional option of viewing the par amet ers) using the Plot or the Contours options . Note tha t these displa y options do not allo w you t o plot the ac tual v alues of the c ell fac es (as is done with the Interpolated D ata option), because the y interpolate the v alues st ored in the adjac ent cells. To view the b oundar y condition par amet ers y ou must first r ead in the pr ofile , save a b oundar y con- dition with a pr ofile field selec ted as a par amet er, and initializ e the flo w solution. Then y ou c an view the sur face da ta as f ollows: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1058Cell Z one and B oundar y Conditions•For 2D c alcula tions , open the Solution X Y Plot dialo g box. Selec t the appr opriate boundar y zone in the Surfaces list, the v ariable of in terest in the Y Axis F unc tion drop-do wn list , and the desir ed Plot D irection . Ensur e tha t the Node Values check butt on is tur ned on, and then click Plot.You should then see the profile plott ed. If the da ta plott ed do es not agr ee with y our sp ecified pr ofile , this means tha t ther e is an error in the pr ofile file . •For 3D c alcula tions , use the Contours dialo g box to displa y contours on the appr opriate boundar y zone surface.The Node Values check butt on must b e tur ned on in or der f or y ou t o view the pr ofile da ta. If the data sho wn in the c ontour plot do es not agr ee with y our sp ecified pr ofile , this means tha t ther e is an er ror in the pr ofile file . 7.7.3.3. Example In Figur e 7.87: Example of U sing P rofiles as B oundar y Conditions (p.1059 ), profiles ar e used t o sp ecify the gauge t otal pr essur e and the x, y, z flo w dir ection c omp onen ts at a pr essur e inlet b oundar y. Figur e 7.87: Example of U sing P rofiles as B oundar y Conditions 7.7.4. Reor ienting P rofiles For 3D c ases only , ANSY S Fluen t allo ws you t o change the or ientation of an e xisting pr ofile so tha t it can b e used a t a b oundar y positioned arbitr arily in spac e.This allo ws you, for e xample , to tak e exper- imen tal da ta for an inlet with one or ientation and apply it t o an inlet in y our mo del tha t has a diff erent spatial or ientation. Note tha t ANSY S Fluen t assumes tha t the pr ofile and the b oundar y are planar . 1059Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Profiles7.7.4.1. Steps for C hanging the P rofile O rientation The pr ocedur e for or ienting the pr ofile da ta in the pr incipal dir ections of a b oundar y is outlined b elow: 1.Define and r ead the pr ofile as descr ibed in Using P rofiles (p.1056 ). 2.In the Profiles D ialog Box (p.3473 ), selec t the pr ofile in the Profile list, and then click the Orient... butt on. This will op en the Orient Profile D ialog Box (p.3476 ) (Figur e 7.88: The Or ient Profile D ialog Box (p.1060 )). Figur e 7.88: The Or ient Profile D ialo g Box 3.In the Orient Profile dialo g box, enter the name of the new pr ofile y ou w ant to create in the New P rofile box. 4.Specify the numb er of fields y ou w ant to create using the up/do wn ar rows ne xt to the New Fields box. The numb er of new fields is equal t o the numb er of v ectors and sc alars t o be defined plus 1 (f or the c o- ordina tes). 5.Define the c oordina te field . a.Enter the names of the thr ee c oordina tes ( , , ) in the first r ow under New Field N ames . Imp ortant Ensur e tha t the c oordina tes ar e named , , and only . Do not use an y other names or upp er case lett ers in this field . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1060Cell Z one and B oundar y Conditionsb.Selec t the appr opriate local coordina te fields f or , , and from the dr op-do wn lists under Comput e From... . (A selec tion of 0 indic ates tha t the c oordina te do es not e xist in the or iginal pr ofile; tha t is, the or iginal pr ofile w as defined in 2D .) 6.Define the v ector fields in the new pr ofile . a.Enter the names of the 3 c omp onen ts in the dir ections of the c oordina te ax es of the b oundar y under New Field N ames . Imp ortant Do not use upp er case lett ers in these fields . b.Selec t the names of the 3 c omp onen ts of the v ector in the lo cal , , and directions of the pr ofile from the dr op-do wn lists under Comput e From... . 7.Define the sc alar fields in the new pr ofile . a.Enter the name of the sc alar in the first c olumn under New Field N ames . Imp ortant Do not use upp er case lett ers in these fields . b.Click the butt on under Treat as Sc alar Q uan tity in the same r ow. c.Selec t the name of the sc alar in the c orresponding dr op-do wn list under Comput e From... . 8.Under Orient To..., specify the r otational ma trix under the Rota tion M atrix [RM] .The r otational matrix used her e is based on E uler angles ( , , and ) tha t define an or thogonal sy stem as the result of the thr ee succ essiv e rotations fr om the or iginal sy stem .That is, (7.205) (7.206) wher e C, B, and A ar e the succ essiv e rotations ar ound the , , and axes, respectively. Rotation ar ound the axis: (7.207) Rotation ar ound the axis: (7.208) 1061Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.ProfilesRotation ar ound the axis: (7.209) 9.Under Orient To..., specify the Direction Vector.The Direction Vector is the v ector tha t transla tes a profile t o the new p osition, and is defined b etween the c enters of the pr ofile fields . Imp ortant Note tha t dep ending on y our c ase, it ma y be nec essar y to perform only a r otation, only a transla tion, or a c ombina tion of a tr ansla tion and a r otation. 10.Click the Create butt on in the Orient Profile dialo g box, and y our new pr ofile will b e created. Its name , which y ou en tered in the New P rofile box, will no w app ear in the Profiles dialo g box and will b e available for use a t the desir ed b oundar y. 7.7.4.2. Profile O rienting E xample Consider the domain with a squar e inlet and outlet , sho wn in Figur e 7.89: Scalar P rofile a t the Out- let (p.1062 ). A sc alar pr ofile a t the outlet is wr itten out t o a pr ofile file .The pur pose of this e xample is to imp ose this outlet pr ofile on the inlet b oundar y via a 90° rotation ab out the axis . However, the rotation will lo cate the pr ofile a way from the inlet b oundar y.To align the pr ofile t o the inlet b oundar y, a transla tion via a dir ectional v ector must b e performed . Figur e 7.89: Scalar P rofile a t the Outlet Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1062Cell Z one and B oundar y ConditionsThe pr oblem is sho wn schema tically in Figur e 7.90: Problem S pecific ation (p.1064 ). is the sc alar profile of the outlet. is the image of the rotated 90° around the axis . In this e xample , sinc e , then , wher e is the iden tity ma trix, and the r otation ma trix is (7.210) To overlay the outlet pr ofile on the inlet b oundar y, a tr ansla tion will b e performed . To overlay the outlet pr ofile on the inlet b oundar y, a tr ansla tion will b e performed .The dir ectional vector is the v ector tha t transla tes to . In this e xample , the dir ectional v ector is . The appr opriate inputs f or the Orient Profile dialo g box are sho wn in Figur e 7.88: The Or ient Profile Dialog Box (p.1060 ). Note tha t if the pr ofile b eing imp osed on the inlet b oundar y was due t o a r otation of -90° about the axis , then the r otational ma trix must b e found f or and , and a new dir ectional vector must b e found t o align the pr ofile t o the b oundar y. 1063Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.ProfilesFigur e 7.90: Problem S pecific ation 7.7.5. Replic ating P rofiles In man y turb omachiner y cases , a pr ofile c an b e obtained fr om an initial small-sc ale simula tion (of ten one passage but sometimes mor e) and then applied t o a lar ger, often full 360 degr ee, simula tion. Replic ating a pr ofile enables y ou t o copy the initial pr ofile p eriodically f or use in a lar ger simula tion. 7.7.5.1. Steps for R eplic ating a P rofile The pr ocedur e for replic ating the pr ofile da ta p eriodically is outlined b elow: 1.Define and r ead the pr ofile as descr ibed in Using P rofiles (p.1056 ). 2.Open the Profiles dialo g box. Physics → Zones → Profiles ... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1064Cell Z one and B oundar y Conditions3.Selec t the pr ofile t o replic ate and click Replic ate... to op en the Replic ate Profile dialo g box (Fig- ure 7.91: The R eplic ate Profile D ialog Box (p.1065 )). Figur e 7.91: The Replic ate Profile D ialo g Box a.Enter a name in the New P rofile field (f or the e xpanded pr ofile name). b.Specify the numb er of fields y ou w ant to create using the up/do wn ar rows ne xt to the New Fields box.The numb er of new fields is equal t o the numb er of v ectors and sc alars t o be defined plus 1 (including the c oordina tes). c.Define the c oordina te field . i.Enter the names of the thr ee c oordina tes (x, y, z) in the first r ow under New Field N ames . Imp ortant Ensur e tha t the c oordina tes ar e named x, y, and z only . Do not use an y other names or upp er case lett ers in this field . ii.Selec t the appr opriate local coordina te fields f or x, y, and z fr om the dr op-do wn lists under Comput e From... . (A selec tion of 0 indic ates tha t the c oordina te do es not e xist in the or iginal profile; tha t is, the or iginal pr ofile w as defined in 2D .) d.Define the v ector fields in the new pr ofile . 1065Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Profilesi.Enter the names of the 3 c omp onen ts in the dir ections of the c oordina te ax es under New Field Names . Imp ortant Do not use upp er case lett ers in these fields . ii.Selec t the names of the 3 c omp onen ts of the v ector in the lo cal coordina tes of the pr ofile fr om the dr op-do wn lists under Comput e From... . e.Define the sc alar fields in the new pr ofile . i.Enter the name of the sc alar in the first c olumn under New Field N ames . Imp ortant Do not use upp er case lett ers in these fields . ii.Selec t Treat as Sc alar Q uan tity in the same r ow. iii.Selec t the name of the sc alar in the c orresponding dr op-do wn list under Comput e From... . 4.Specify the r eplic ation settings in the Current Profile D efinitions group b ox. a.If you ar e creating a full 360 degr ee pr ofile , selec t Full 360 deg .. Fluen t aut oma tically det ermines the numb er of c opies of the or iginal pr ofile tha t are needed t o mak e the full 360 degr ee pr ofile based on the other inf ormation y ou sp ecify . b.If you did not selec t Full 360 deg ., you must sp ecify the Numb er of c opies to manually det ermine how man y copies of the or iginal pr ofile ar e created. c.The Numb er of sec tors in 360 deg . is the numb er of p eriodic sec tions , based on the or iginal pr ofile , that are pr esen t in 360 degr ees. d.The Numb er of sec tors in pr ofile is the numb er of p eriodic sec tions in the or iginal pr ofile . e.The Calcula ted angle is for displa y only and is the angle o ccupied b y the or iginal pr ofile .When using the Full 360 deg . option, you c an det ermine the numb er of c opies tha t are created b y dividing 360 by the Calcula ted angle . f.Specify the Rota tion-A xis D irection .This is the X,Y, and Z comp onen ts of the axis ab out which the selec ted pr ofile is r eplic ated. 5.Click the Create butt on in the Replic ate Profile dialo g box, and y our new pr ofile will b e created. Its name , which y ou en tered in the New P rofile box, will no w app ear in the Profiles dialo g box and will b e available f or use a t the desir ed b oundar y. 7.7.6. Defining Transien t Cell Z one and B oundar y Conditions There ar e thr ee w ays you c an sp ecify tr ansien t cell z one and b oundar y conditions: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1066Cell Z one and B oundar y Conditions•transien t profile with a f ormat similar t o the standar d pr ofiles descr ibed in Profiles (p.1051 ) •transien t profile in a tabular f ormat •transien t profile in c omma separ ated v alues (CSV ) format, as descr ibed in CSV P rofiles (p.1054 ). Imp ortant For b oth metho ds, the c ell z one or b oundar y condition will v ary only in time; it must b e spatially unif orm. However, if the in-c ylinder mo del is ac tivated ( In-C ylinder S ettings (p.1313 )), then y ou ha ve the option t o use the cr ank angle inst ead of time . Crank angles c an b e in- cluded in tr ansien t tables as w ell as tr ansien t profiles , in a similar fashion t o time . Examples of tr ansien t profiles and tr ansien t tables in cr ank angle c an b e found in the sec tions tha t follow. For inf ormation ab out b oundar y pr ofiles , refer to Reading and Writing P rofile F iles (p.594). 7.7.6.1. Standar d Transient P rofiles The f ormat of the standar d transien t profile file (based on the pr ofiles descr ibed in Profiles (p.1051 )) is ((profile-name transient n periodic?) (field_name-1 a1 a2 a3 .... an) (field_name-2 b1 b2 b3 .... bn) . . . . (field_name-r r1 r2 r3 .... rn)) The pr ofile name as w ell as the field names ha ve to be shor ter than 64 char acters. One of the field_name s should b e used f or the time field , and the time field sec tion must be in asc ending order. n is the numb er of en tries p er field .The periodic? entry indic ates whether or not the pr ofile is time-p eriodic. Set it t o 1 for a time-p eriodic pr ofile , or 0 if the pr ofile is not time-p eriodic. An example is sho wn b elow: ((sampleprofile transient 3 0) (time 1 2 3 ) (u 10 20 30 ) ) This e xample demonstr ates the use of cr ank angle in a tr ansien t profile ((example transient 3 1) (angle 0.000000e+00 1.800000e+02 3.600000e+02) (temperature 1067Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Profiles 3.000000e+02 5.000000e+02 3.000000e+02) ) Imp ortant All quan tities , including c oordina te values , must b e sp ecified in SI units b ecause ANSY S Fluen t do es not p erform unit c onversion when r eading pr ofile files . Also, profile names must ha ve all lo wercase lett ers (f or e xample ,name ). Uppercase lett ers in pr ofile names ar e not acc eptable . You c an r ead this file in to ANSY S Fluen t using the Profiles D ialog Box (p.3473 ) or the File/Read/P rofile ... ribbon tab it em. Setup → Cell Z one C onditions → Profiles ... Setup → Boundar y Conditions → Profiles ... File → Read → Profile ... See Using P rofiles (p.1056 ) for details . 7.7.6.2. Tabular Transient P rofiles The f ormat of the tabular tr ansien t profile file is profile-name n_field n_data periodic? field-name-1 field-name-2 field-name-3 .... field-name-n_field v-1-1 v-2-1... ... ... ... v-n_field-1 v-1-2 v-2-2... ... ... ... v-n_field-2 . . . . . v-1-n_data v-2-n_data ... ... ... ... v-n_field-n_data The first field name (f or e xample field-name-1 ) should b e used f or the time field , and the time field sec tion, which r epresen ts the flo w time ,must be in asc ending or der.The periodic? entry in- dicates whether or not the pr ofile is time-p eriodic. Set it t o 1 for a time-p eriodic pr ofile , or 0 if the profile is not time-p eriodic. An example is sho wn b elow: sampletabprofile 2 3 0 time u 1 10 2 20 3 30 This file defines the same tr ansien t profile as the standar d pr ofile e xample ab ove. If the p eriodicit y is set t o 1, then n_data must b e the numb er tha t closes one p eriod. An example is sho wn b elow: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1068Cell Z one and B oundar y Conditions periodtabprofile 2 4 1 time u 0 10 1 20 2 30 3 10 The f ollowing e xample uses cr ank angle inst ead of time: example 2 3 1 angle temperature 0 300 180 500 360 300 Imp ortant •All quan tities , including c oordina te values , must b e sp ecified in SI units b ecause ANSY S Flu- ent do es not p erform unit c onversion when r eading pr ofile files . Also, profile names must ha ve all lo wercase lett ers (f or e xample ,name ). Uppercase lett ers in pr ofile names ar e not acc eptable . When cho osing the field names , spac es or par entheses should not b e included . •Some file f ormats ma y not b e read in to Fluen t correctly (f or e xample , UCS-2). If your file is not read c orrectly, copy the c ontents in to a t ext edit or (N otepad++/VIM/N otepad) and sa ve it. This updated v ersion of y our pr ofile is no w readable in F luen t. You c an r ead this file in to ANSY S Fluen t using the read-transient-table text command . file → read-transient-table After reading the table in to ANSY S Fluen t, the pr ofile will b e list ed in the Profiles D ialog Box (p.3473 ) and c an b e used in the same w ay as a b oundar y pr ofile . See Using P rofiles (p.1056 ) for details . 7.7.6.3. Profiles for Mo ving and D eforming Meshes You c an use pr ofiles t o sp ecify p osition, velocity, and angular v elocity.There ar e two diff erent valid profile f ormats for mo ving and def orming mesh c ases . profile-name n_field n_data periodic? field-name-1 field-name-2 field-name-3 .... field-name-n_field v-1-1 v-2-1... ... ... ... v-n_field-1 v-1-2 v-2-2... ... ... ... v-n_field-2 . . . . . v-1-n_data v-2-n_data ... ... ... ... v-n_field-n_data and ((profile-name transient n periodic?) (field_name-1 a1 a2 a3 .... an) (field_name-2 b1 b2 b3 .... bn) . . . . (field_name-r r1 r2 r3 .... rn)) 1069Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.ProfilesYou must use the appr opriate variable nomencla ture when wr iting y our pr ofile so tha t Fluen t can properly in terpret y our inputs . For p osition, use x,y, and z. For sp ecifying v elocity, use v_x ,v_y , and v_z . Similar ly, for angular v elocity, use omega_x ,omega_y , and omega_z . 7.8. Coupling B oundar y Conditions with GT-PO WER GT-PO WER users c an define time-dep enden t boundar y conditions in ANSY S Fluen t based on inf ormation from GT-PO WER. During the ANSY S Fluen t simula tion, ANSY S Fluen t and GT-PO WER ar e coupled t ogether and inf ormation ab out the b oundar y conditions a t each time st ep is tr ansf erred b etween them. 7.8.1. Requir emen ts and R estrictions 7.8.2. User Inputs 7.8.3. Torque-S peed C oupling with GT-PO WER 7.8.1. Requir emen ts and Restr ictions Note the f ollowing r equir emen ts and r estrictions f or the GT-PO WER c oupling: •The flo w must b e unst eady. •The c ompr essible ideal gas la w must b e used f or densit y. •Each b oundar y zone f or which y ou plan t o define c onditions using GT-PO WER must b e a b oundar y of one of the f ollowing t ypes: –velocity inlet –mass-flo w inlet –pressur e inlet –pressur e outlet –wall (f or details , see Torque-S peed C oupling with GT-PO WER (p.1074 )) Also, a maximum of 20 b oundar y zones c an b e coupled t o GT-PO WER. •Fluen t checks the ar ea of the 1D c oupled b oundar y as c alcula ted b y Fluen t and GT-PO WER t o ensur e the calcula ted ar eas diff er b y no mor e than 5%. When the diff erence is mor e than 5%, Fluen t stops with an error message and displa ys the t wo ar eas. •If a mass-flo w inlet or pr essur e inlet is c oupled t o GT-PO WER, you must selec t Normal t o Boundar y as the Direction S pecific ation M etho d in the Mass-F low Inlet or Pressur e Inlet dialo g box. For a v elocity inlet , you must selec t Magnitude , Normal t o Boundar y as the Velocity Specific ation M etho d in the Velocity Inlet dialo g box. •The mass flo w sp ecific ation metho d in the Mass-F low Inlet boundar y has t o alw ays be Mass F lux and not Mass F low R ate when c oupling with GTP ower. •Boundar y conditions f or the f ollowing v ariables c an b e obtained fr om GT-PO WER: –velocity –temp erature Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1070Cell Z one and B oundar y Conditions–pressur e –densit y –species mass fr actions – and (Note tha t it is r ecommended tha t you define these c onditions in ANSY S Fluen t yourself , rather than using the da ta pr ovided b y GT-PO WER, sinc e the GT-PO WER v alues ar e based on a 1D mo del.) •Make sur e tha t the ma terial pr operties y ou set in ANSY S Fluen t are the same as those used in GT-PO WER, so tha t the b oundar y conditions will b e valid f or y our c oupled simula tion. •If your mo del includes sp ecies , mak e sur e tha t the name of each sp ecies in GT-PO WER c orresponds t o the Chemic al F ormula for tha t species ma terial in the Materials dialo g box. Also, recall tha t ANSY S Fluen t can handle a maximum of 50 sp ecies . •You c an install the GT-PO WER libr aries in a dir ectory other than the default lo cation. If the GT-PO WER lib- raries ar e loaded in to a non-default lo cation, you need t o set the f ollowing en vironmen t variables: –Fluent_GTIHOME — the GTI installa tion dir ectory wher e GT-PO WER is installed –Fluent_GTIVERSION — the cur rent version of the GTI installa tion Imp ortant GTI is not back wards c ompa tible . 7.8.2. User Inputs The pr ocedur e for setting up the GT-PO WER c oupling in ANSY S Fluen t is pr esen ted b elow. 1.Read in the mesh file and define the mo dels , materials, and b oundar y zone t ypes (but not the ac tual boundar y conditions), noting the r equir emen ts and r estrictions list ed in Requir emen ts and R estric- tions (p.1070 ). 2.Specify the lo cation of the GT-PO WER da ta and ha ve ANSY S Fluen t use them t o gener ate user-defined func tions f or the r elevant boundar y conditions (using the 1D S imula tion Libr ary Dialog Box (p.3776 ), sho wn in Figur e 7.92: The 1D S imula tion Libr ary Dialog Box (p.1072 )). User D efined → Model S pecific → 1D C oupling ... 1071Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Coupling B oundar y Conditions with GT-PO WERFigur e 7.92: The 1D S imula tion Libr ary D ialo g Box a.Selec t GTp ower in the 1D Libr ary drop-do wn list. b.Specify the name of the GT-PO WER input file in the 1D Input F ile N ame field . c.Click the Start butt on. When y ou click Start, GT-PO WER will star t up and ANSY S Fluen t user-defined func tions f or each boundar y in the input file will b e gener ated. 3.Set b oundar y conditions f or all z ones . For flo w boundar ies f or which y ou ar e using GT-PO WER da ta, selec t the appr opriate UDFs as the c onditions . Imp ortant Note tha t you must selec t the same UDF f or all c onditions a t a par ticular b oundar y zone (as sho wn, for e xample , in Figur e 7.93: Using GT-PO WER D ata for B oundar y Condi- tions (p.1073 )); this UDF c ontains all of the c onditions a t tha t boundar y. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1072Cell Z one and B oundar y ConditionsFigur e 7.93: Using GT-PO WER D ata f or B oundar y Conditions 4.If you plan t o continue the simula tion a t a la ter time , star ting fr om the final da ta file of the cur rent simu- lation, specify ho w of ten y ou w ant to ha ve the c ase and da ta files sa ved aut oma tically. Solution → Calcula tion A ctivities (Autosa ve Case/D ata) → Edit... To use a GT-PO WER r estar t file t o restar t an ANSY S Fluen t calcula tion, you must edit the GT-PO WER input da ta file . See the GT-PO WER U ser’s Guide f or instr uctions . 5.Continue the pr oblem setup and c alcula te a solution in the usual manner . 1073Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Coupling B oundar y Conditions with GT-PO WER7.8.3. Torque-S peed C oupling with GT-PO WER Torque-sp eed c oupling with GT-PO WER is a unique c ase in which F luen t receives shaf t sp eed fr om GT-PO WER and r etur ns torque .The pr ocedur e diff ers fr om the t ypic al coupling b etween GT-P ower and F luen t, and is as f ollows: Imp ortant You must b e using GT-PO WER v2017.2 or gr eater to perform torque-sp eed c oupling with ANSY S Fluen t. 1.Complet e steps 1 and 2 in the ab ove sec tion on User Inputs (p.1071 ).The .dat file should ha ve at least one turb o-machine e xposed t o complet e the c oupling . 2.Enable Frame M otion in the c ell z one tha t is r eceiving shaf t speed fr om GT-P ower.You must also selec t the appr opriate UDF f or Rota tional Velocity.The UDF must c orrespond t o the turb o-machine e xposed from GT-PO WER ("turbine", in the e xample sho wn b elow). Figur e 7.94: Cell Z one C onditions f or Torque-S peed C oupling with GT-PO WER 3.Specify a Wall boundar y on which the t orque is c alcula ted and tr ansf erred t o GT-PO WER. The following requir emen ts apply : •The w all b oundar y must b e attached t o the r otating c ell z one fr om st ep 2, to receive the shaf t speed from GT-PO WER. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1074Cell Z one and B oundar y Conditions•The name of the w all b oundar y must b e the same as the turb o-machine it is c oupled with ("turbine", in the c ase pr esen ted ab ove). During the solution, shaf t sp eed is obtained fr om GT-PO WER a t every time-st ep, with F luen t calcula ting and r etur ning t orque within each time-st ep as w ell. 7.9. Coupling B oundar y Conditions with WAVE WAVE users c an define time-dep enden t boundar y conditions in ANSY S Fluen t based on inf ormation from WAVE. During the ANSY S Fluen t simula tion, ANSY S Fluen t and WAVE ar e coupled t ogether and information ab out the b oundar y conditions a t each time st ep is tr ansf erred b etween them. 7.9.1. Requir emen ts and R estrictions 7.9.2. User Inputs 7.9.1. Requir emen ts and Restr ictions Note the f ollowing r equir emen ts and r estrictions f or the WAVE c oupling: •WAVE must b e installed and lic ensed . •There are alw ays fiv e sp ecies tha t must b e mo deled in ANSY S Fluen t just as the y are defined in WAVE (F1, F2,F3,F4, and F5). It is r ecommended tha t realistic ma terial pr operties b e assigned t o each of the fiv e species . •The flo w must b e unst eady. •The c ompr essible ideal gas la w must b e used f or densit y. •Each b oundar y zone f or which y ou plan t o define c onditions using WAVE must b e a flo w boundar y of one of the f ollowing t ypes: –velocity inlet –mass-flo w inlet –pressur e inlet –pressur e outlet Also, a maximum of 20 b oundar y zones c an b e coupled t o WAVE. •If a mass-flo w inlet or pr essur e inlet is c oupled t o WAVE, you must selec t Normal t o Boundar y as the Dir- ection S pecific ation M etho d in the Mass-F low Inlet or Pressur e Inlet Dialog Box. For a v elocity inlet , you must selec t Magnitude , Normal t o Boundar y as the Velocity Specific ation M etho d in the Velocity Inlet Dialog Box. •Boundar y conditions f or the f ollowing v ariables c an b e obtained fr om WAVE: –velocity –temp erature –pressur e 1075Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Coupling B oundar y Conditions with WAVE–densit y –species mass fr actions – and (Note tha t you ar e requir ed t o define these c onditions in ANSY S Fluen t yourself , sinc e WAVE does not c alcula te them.) •Make sur e tha t the ma terial pr operties y ou set in ANSY S Fluen t are the same as those used in WAVE, so that the b oundar y conditions will b e valid f or y our c oupled simula tion. •If your mo del includes sp ecies , mak e sur e tha t the name of each sp ecies in WAVE c orresponds t o the Chemic al F ormula for tha t species ma terial in the Create/Edit M aterials dialo g box. Also, recall tha t ANSY S Fluen t can handle a maximum of 50 sp ecies . 7.9.2. User Inputs The pr ocedur e for setting up the WAVE c oupling in ANSY S Fluen t is pr esen ted b elow. 1.Read in the mesh file and define the mo dels , materials, and b oundar y zone t ypes. 2.Specify the lo cation of the WAVE da ta and ha ve ANSY S Fluen t use them t o gener ate user-defined func tions for the r elevant boundar y conditions (using the 1D S imula tion Libr ary Dialog Box (p.3776 ), sho wn in Fig- ure 7.95: The 1D S imula tion Libr ary Dialog Box with WAVE S elec ted (p.1076 )). User D efined → Model S pecific → 1D C oupling ... Figur e 7.95: The 1D S imula tion Libr ary D ialo g Box with WAVE S elec ted a.Selec t WAVE in the 1D Libr ary drop-do wn list. b.Specify the name of the WAVE input file in the 1D Input F ile N ame field . c.Click the Start butt on. When y ou click Start,WAVE will star t up and ANSY S Fluen t user-defined func tions f or each boundar y in the input file will b e gener ated. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1076Cell Z one and B oundar y Conditions3.Set b oundar y conditions f or all z ones . For flo w boundar ies f or which y ou ar e using WAVE da ta, selec t the appr opriate UDFs as the c onditions . Imp ortant Note tha t you must selec t the same UDF f or all c onditions a t a par ticular b oundar y zone (as sho wn, for e xample , in Figur e 7.96: Using WAVE D ata for B oundar y Conditions (p.1077 )); this UDF c ontains all of the c onditions a t tha t boundar y. Figur e 7.96: Using WAVE D ata f or B oundar y Conditions 4.If you plan t o continue the simula tion a t a la ter time , restar ting fr om the final da ta file of the cur rent simula tion, you need t o instr uct both ANSY S Fluen t and WAVE ho w of ten tha t you w ant to aut oma tically save your da ta.You should instr uct ANSY S Fluen t to aut oma tically sa ve case and da ta files a t specified intervals using the aut osave feature. Solution → Calcula tion A ctivities → Autosa ve On 1077Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Coupling B oundar y Conditions with WAVEIn addition, you should instr uct WAVE as t o ho w of ten it should gener ate its o wn r estar t files . See the WAVE U ser's G uide f or instr uctions on this f eature. Imp ortant To use the r estar t feature, the time in terval for wr iting da ta files must b e set t o the same value in b oth ANSY S Fluen t and WAVE. For e xample , if ANSY S Fluen t has set the aut osave feature to 100, then WAVE must also set the r estar t file wr ite frequenc y to 100 as w ell. 5.Continue the pr oblem setup and c alcula te a solution in the usual manner . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1078Cell Z one and B oundar y ConditionsChapt er 8: Physical P roperties This chapt er descr ibes ho w to define ma terials, the ph ysical equa tions used t o comput e ma terial properties, and the metho ds y ou c an use f or each pr operty input. Each pr operty is descr ibed in detail in the f ollowing sec tions . If you ar e using one of the gener al multiphase mo dels ( VOF, mix ture, or E u- lerian), see Defining the P hases (p.2103 ) for inf ormation ab out ho w to define the individual phases and their ma terial pr operties. 8.1. Defining M aterials 8.2. Defining P roperties U sing Temp erature-Dependen t Functions 8.3. Densit y 8.4.Viscosity 8.5.Thermal C onduc tivit y 8.6. User-D efined Sc alar (UDS) D iffusivit y 8.7. Specific H eat Capacit y 8.8. Radia tion P roperties 8.9. Mass D iffusion C oefficien ts 8.10. Standar d State En thalpies 8.11. Standar d State En tropies 8.12. Unbur nt Thermal D iffusivit y 8.13. Kinetic Theor y Paramet ers 8.14. Operating P ressur e 8.15. Reference Pressur e Location 8.16. Real G as M odels 8.1. Defining M aterials An imp ortant step in the setup of the mo del is t o define the ma terials and their ph ysical pr operties. Material pr operties ar e defined using either the Materials Task P age (p.3384 ) or the Materials tree br anch, wher e you c an en ter v alues f or the pr operties tha t are relevant to the pr oblem sc ope you ha ve defined in the Models Task P age (p.3245 ).These pr operties ma y include the f ollowing: •densit y and/or molecular w eigh ts •viscosity •heat capacit y •ther mal c onduc tivit y •UDS diffusion c oefficien ts •mass diffusion c oefficien ts •standar d sta te en thalpies •kinetic theor y par amet ers 1079Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Properties ma y be temp erature-dep enden t and/or c omp osition-dep enden t, with t emp erature dep endenc e based on a p olynomial, piec ewise-linear , or piec ewise-p olynomial func tion and individual c omp onen t properties either defined b y you or c omput ed via k inetic theor y. The Materials Task P age (p.3384 ) will sho w the pr operties tha t need t o be defined f or the ac tive ph ysical models . If an y pr operty you define r equir es the ener gy equa tion t o be solv ed (f or e xample , ideal gas law for densit y, temp erature-dep enden t profile f or visc osity), ANSY S Fluen t will aut oma tically enable the ener gy equa tion. Then y ou ha ve to define the ther mal b oundar y conditions and other par amet ers yourself . For additional inf ormation, see the f ollowing sec tions: 8.1.1. Physical Properties f or Solid M aterials 8.1.2. Material Types and D atabases 8.1.3. Using the C reate/Edit M aterials D ialog Box 8.1.4. Using a U ser-D efined M aterials D atabase 8.1.1. Physical P roperties f or S olid M aterials For solid ma terials, only densit y, ther mal c onduc tivit y, and hea t capacit y are defined . If you ar e mo d- eling semi-tr anspar ent media, then r adia tion pr operties ar e also defined .You c an sp ecify a c onstan t value , a temp erature-dep enden t func tion, or a user-defined func tion f or ther mal c onduc tivit y; a constan t value or t emp erature-dep enden t func tion f or hea t capacit y; and a c onstan t value f or densit y. If you ar e using the pr essur e-based solv er, densit y and hea t capacit y for a solid ma terial ar e not r equir ed unless y ou ar e mo deling tr ansien t flo w or mo ving solid z ones . Heat capacit y will app ear in the list of solid pr operties f or st eady flo ws as w ell.The v alue will b e used just f or p ostpr ocessing en thalp y; not in the c alcula tion. 8.1.2. Material Types and D atabases In ANSY S Fluen t, you c an define six t ypes of ma terials: fluids , solids , mix tures, combusting-par ticles , droplet-par ticles , and iner t-par ticles . Physical pr operties of fluids and solids ar e asso ciated with named material; these ma terials ar e then assigned as b oundar y conditions f or z ones . When y ou mo del sp ecies tr ansp ort, define a mix ture ma terial, consisting of the v arious sp ecies in volved in the pr oblem. Properties will b e defined f or the mix ture, as w ell as f or the c onstituen t sp ecies , which are fluid ma terials.The mix ture ma terial c oncept is discussed in detail in Mixture M aterials (p.1615 ). Combusting-par ticles , droplet-par ticles , and iner t-par ticles ar e available f or the discr ete-phase mo del, as descr ibed in The C oncept of D iscrete-Phase M aterials (p.2011 ). ANSY S Fluen t provides a built-in global da tabase of appr oxima tely 675 pr edefined ma terials along with their pr operties and default v alues f or each pr operty.To define a ma terial in the pr oblem setup , you c an c opy ma terials fr om this global (sit e-wide) da tabase and use the default pr operties or define new ma terials b y editing their pr operties.The ANSY S Fluen t ma terials da tabase is lo cated in the f ol- lowing file: path/ansys_inc/v195/fluent/fluent19.5.0/cortex/lib/propdb.scm wher e path is the dir ectory in which y ou installed ANSY S Fluen t. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1080Physical PropertiesIn addition t o using the ANSY S Fluen t ma terial da tabase , you c an also cr eate your o wn da tabase and materials, and use it t o define the ma terials in y our pr oblem setup . See Using a U ser-D efined M aterials Database (p.1087 ) for inf ormation ab out cr eating and using user-defined cust om ma terial da tabases . Imp ortant All the ma terials in y our lo cal ma terials list will b e sa ved in the c ase file (when y ou wr ite one). The ma terials sp ecified b y you will b e available t o you if y ou r ead this c ase file in to a new solv er session. 8.1.3. Using the Create/Edit M aterials Dialo g Box The Create/Edit M aterials D ialog Box (p.3386 ) allo ws you t o define the ma terials and their pr operties in your pr oblem setup using either the Fluen t Database or a User-D efined D atabase . It enables y ou t o copy ma terials fr om a da tabase , create new ma terials, and mo dify ma terial pr operties. These gener ic func tions ar e descr ibed in this sec tion. The inputs f or temp erature-dep enden t properties are explained in Defining P roperties U sing Temp erature-Dependen t Functions (p.1095 ).The sp ecific inputs for each ma terial pr operty are discussed in the r emaining sec tions of this chapt er. The Create/Edit M aterials D ialog Box (p.3386 ) can b e acc essed in one of t wo ways: •Through the Materials task page . Setup → Materials 1081Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Defining M aterialsFigur e 8.1: The M aterials Task P age •Through the ma terial types (Fluid ,Solid , and so on) and defined in the c ase ma terials under Materials in the tr ee. For e xample , if y ou w ant to cr eate a new fluid ma terial y ou c an acc ess the Create/Edit M aterials dialo g box as f ollows: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1082Physical PropertiesSetup → Materials → Fluid New... Figur e 8.2: The M aterials Br anch in the Outline View By default , your lo cal ma terials list will include a single fluid ma terial (air) and a single solid ma terial (aluminum). If the fluid in volved in y our pr oblem is air , you c an use the default pr operties f or air or modify the pr operties. If the fluid in y our pr oblem is w ater, you c an either c opy water fr om the ANSY S Fluen t da tabase or cr eate a new “water” ma terial fr om scr atch. If you c opy water fr om the da tabase , you c an still mak e mo dific ations t o the pr operties of y our lo cal copy of w ater. See the f ollowing sec tions for detailed inf ormation on ho w to change ma terial pr operties. Mixture ma terials will not e xist in y our lo cal list unless y ou ha ve enabled sp ecies tr ansp ort (see Modeling Species Transp ort and F inite-Rate Chemistr y (p.1613 )). Similar ly, iner t, droplet , and c ombusting par ticle materials will not b e available unless y ou ha ve created a discr ete phase injec tion of these par ticle t ypes (see Modeling D iscrete Phase (p.1911 )).When a mix ture ma terial is c opied fr om the da tabase , all of its constituen t fluid ma terials (sp ecies) will aut oma tically b e copied o ver as w ell. 8.1.3.1. Mo difying P roperties of an E xisting M aterial Probably , the most c ommon op eration y ou will p erform in the Create/Edit M aterials D ialog Box (p.3386 ) is the mo dific ation of pr operties f or an e xisting ma terial.The st eps f or this pr ocedur e ar e as f ollows: 1.In the Materials Task P age (p.3384 ), selec t the ma terial y ou w ant to mo dify and click the Create/Edit... butt on. (You c an also r ight-click the ma terial in the tr ee and selec t Edit... from the ma terial submenu .) 2.In the Create/Edit M aterials D ialog Box (p.3386 ) selec t the t ype of ma terial (fluid ,solid , and so on) in the Material Type drop-do wn list. 3.Choose the ma terial for which y ou w ant to mo dify pr operties, in the Fluen t Fluid M aterials drop-do wn list,Fluen t Solid M aterials list, or other similar ly named list. The name of the list will b e the same as the material type you selec ted in the pr evious st ep. 4.Make the r equir ed changes t o the pr operties list ed in the Properties sec tion of the dialo g box.You c an use the scr oll bar t o the r ight of the Properties sec tion t o scr oll thr ough the list ed it ems . 5.Click the Change/C reate butt on t o change the pr operties of the selec ted ma terial to your new pr operty settings . 1083Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Defining M aterialsTo change the pr operties of an additional ma terial, repeat the pr ocess descr ibed ab ove. Click the Change/C reate butt on af ter mak ing changes t o the pr operties f or each ma terial. 8.1.3.2. Renaming an E xisting M aterial Each ma terial is iden tified b y a name and a chemic al formula (if one e xists). You c an change the name of a ma terial, but not its chemic al formula (unless y ou ar e creating a new ma terial). The pr ocedur e for renaming a ma terial is as f ollows: 1.In the Materials Task P age (p.3384 ), selec t the ma terial y ou w ant to rename and click the Create/Edit... butt on. (You c an also r ight-click the ma terial in the tr ee and selec t Edit... from the ma terial submenu .) 2.In the Create/Edit M aterials D ialog Box (p.3386 ), cho ose the ma terial for which y ou w ant to mo dify pr op- erties, in the Fluen t Fluid M aterials list,Fluen t Solid M aterials list, or other similar ly named list. The name of the list will b e the same as the ma terial type you selec ted in the pr evious st ep. 3.Enter the new name in the Name field a t the t op of the Create/Edit M aterials D ialog Box (p.3386 ). Imp ortant The maximum char acter length y ou c an en ter in the Name field is 29. If you en ter a material name tha t is mor e than 29 char acters long , ANSY S Fluen t will pr int an er ror message in the c onsole windo w. 4.Click the Change/C reate butt on. A Question D ialog Box (p.569) will app ear, ask ing y ou if the or iginal ma terial should b e overwritten. If you ar e renaming the or iginal ma terial, click Yes to overwrite it. If you w ere creating a new material, click No to retain the or iginal ma terial. To rename another ma terial, repeat the pr ocess descr ibed ab ove. Click the Change/C reate butt on after renaming each ma terial. 8.1.3.3. Copying M aterials fr om the ANSY S Fluent D atabase The global (sit e-wide) ma terials da tabase c ontains man y commonly used fluid , solid , and mix ture materials, with pr operty da ta fr om se veral diff erent sour ces [74] (p.4009 ),[103] (p.4010 ),[144] (p.4013 ), [50] (p.4007 ).To use one of these ma terials in y our pr oblem, copy it fr om the ANSY S Fluen t da tabase to your lo cal ma terials list. The pr ocedur e for c opying a ma terial is as f ollows: 1.Click the Fluen t Database ... butt on in the Create/Edit M aterials D ialog Box (p.3386 ) to op en the Fluen t Database M aterials D ialog Box (p.3396 ) (Figur e 8.3: Fluen t Database M aterials D ialog Box (p.1085 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1084Physical PropertiesFigur e 8.3: Fluen t Database M aterials D ialo g Box 2.Selec t the t ype of ma terial (fluid ,solid , and so on) in the Material Type drop-do wn list. 3.In the Fluen t Fluid M aterials list,Fluen t Solid M aterials list, or other similar ly named list , cho ose the materials y ou w ant to copy by click ing on them. The pr operties of the selec ted ma terial will b e displa yed in the Properties area. 4.To check the ma terial pr operties, use the scr oll bar t o the r ight of the Properties area to scr oll thr ough the list ed it ems . For some pr operties, temp erature-dep enden t func tions ar e available in addition t o the constan t values . Selec t one of the func tion t ypes in the dr op-do wn list t o the r ight of the pr operty and the r elevant par amet ers will b e displa yed.You c annot edit these v alues , but the dialo g boxes in which they are displa yed func tion in the same w ay as those used f or setting t emp erature-dep enden t property func tions ( Defining P roperties U sing Temp erature-Dependen t Functions (p.1095 )). The inac tive butt ons in the Fluent D atabase Mat erials D ialo g Box (p.3396 ) are op erations that ar e ap- plic able onl y for a user -defined database .These op erations will b e available when y ou click the User - Defined D atabase ... butt on in the Create/Edit Mat erials D ialo g Box (p.3386 ). 5.Click Copy. 1085Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Defining M aterialsThe ma terials and their pr operties will b e do wnloaded fr om the da tabase in to your lo cal list , and your c opy of pr operties will no w b e displa yed in the Materials Task P age (p.3384 ) and in the tr ee under the appr opriate ma terial t ype. 6.Close the Fluen t Database M aterials D ialog Box (p.3396 ). After copying a ma terial fr om the da tabase , you c an mo dify its pr operties or change its name , as descr ibed ear lier in this sec tion. The or iginal ma terial in the da tabase will not b e aff ected b y an y changes made t o your lo cal copy of the ma terial. 8.1.3.4. Creating a N ew M aterial If the ma terial y ou w ant to use is not a vailable in the da tabase , you c an easily cr eate a new ma terial for the lo cal list. This ma terial will b e available f or use only f or the cur rent problem and will not b e saved in the ANSY S Fluen t da tabase .The pr ocedur e for cr eating a new ma terial is as f ollows: 1.In the Materials Task P age (p.3384 ), click the Create/Edit... butt on. (You c an also r ight-click the c orrespond- ing ma terial type in the tr ee ( Fluid ,Solid , and so on) and selec t New... from the ma terial type submenu .) 2.Selec t the new ma terial type (fluid ,solid , and so on) in the Material Type drop-do wn list. It do es not matter which ma terial is selec ted in the Fluen t Fluid M aterials,Fluen t Solid M aterials, or other similar ly named list. 3.Enter the new ma terial name in the Name field . Imp ortant The maximum char acter length y ou c an en ter in the Name field is 29. If you en ter a material name tha t is mor e than 29 char acters long , ANSY S Fluen t will pr int an er ror message in the c onsole windo w. 4.Set the ma terial’s properties in the Properties area. If ther e are man y pr operties list ed, you ma y use the scroll bar t o the r ight of the Properties area to scr oll thr ough the list ed it ems . 5.Click the Change/C reate butt on. A Question D ialog Box (p.569) will app ear, ask ing y ou if the or iginal material should b e overwritten. a.Click No to retain the or iginal ma terial and add your new ma terial to the list. A dialo g box will app ear asking y ou t o en ter the chemic al formula of y our new ma terial. b.Click OK, enter the f ormula if it is k nown. Else, leave the f ormula blank and click OK. Selec t the Change/C reate butt on and answ er the Question . The Materials Task P age (p.3384 ) and the Material tree br anch will b e up dated t o sho w the new ma terial name and chemic al formula under the appr opriate ma terial t ype (Fluid ,Solid , or others). 8.1.3.5. Saving M aterials and P roperties All the ma terials and pr operties in y our lo cal list ar e sa ved in the c ase file when it is wr itten. If you read this c ase file in to a new solv er session, all of y our ma terials and pr operties will b e available f or use in the new session. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1086Physical Properties8.1.3.6. Deleting a M aterial If ther e ar e ma terials list tha t you no longer need , you c an delet e them in one of the f ollowing w ays: •Using the Materials Task P age (p.3384 ). In the Materials Task P age (p.3384 ), selec t the ma terial t o be delet ed and click the Delet e butt on a t the b ottom of the Materials Task P age (p.3384 ). •Using the tr ee. Right-click the ma terial in the tr ee and selec t Delet e from the ma terial submenu . •Using the Create/Edit M aterials D ialog Box (p.3386 ). 1.From the Material Type drop-do wn list , selec t the t ype of ma terial (fluid ,solid , and so on). 2.Selec t the ma terial to be delet ed fr om the Fluen t Fluid M aterials drop-do wn list ,Fluen t Solid M ater- ials list, or other similar ly named list. The list ’s name will b e the same as the ma terial type you selec ted in the pr evious st ep. 3.Click the Delet e butt on. Deleting ma terials fr om y our lo cal list will ha ve no eff ect on the ma terials c ontained in the global database . 8.1.3.7. Changing the O rder of the M aterials List By default , the ma terials in y our lo cal list and those in the da tabase ar e list ed alphab etically b y name (for e xample ,air,atomic-o xygen (o) ,carb on-dio xide (c o2)). If you pr efer to list them alphab etically by chemic al formula, selec t the Chemic al F ormula option under Order M aterials B y.The e xample materials list ed, will no w b e in the or der of :air,co2 (c arb on-dio xide) ,o (a tomic-o xygen) .To change back t o the alphab etical listing b y name , cho ose the Name option under Order M aterials B y. You ma y sp ecify the or dering metho d separ ately f or the Create/Edit M aterials D ialog Box (p.3386 ) and Fluen t Database M aterials D ialog Box (p.3396 ). For e xample , you c an or der the da tabase ma terials list by name . Each dialo g box has its o wn Order M aterials B y options . 8.1.4. Using a U ser-D efined M aterials D atabase In addition t o the Fluen t Database M aterials D ialog Box (p.3396 ), you c an also use or cr eate a user- defined ma terials da tabase using the User-D efined D atabase M aterials D ialog Box (p.3398 ).You c an browse and do the f ollowing: •selec t from e xisting user-defined da tabases •copy ma terials fr om a user-defined da tabase •create a new da tabase , create new ma terials •add them t o the user-defined da tabase •delet e ma terials fr om the da tabase 1087Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Defining M aterials•copy ma terials fr om a c ase t o a user-defined da tabase •view the da tabase The f ollowing sec tions will addr ess each of these func tionalities in detail. 8.1.4.1. Opening a User -Defined D atabase In ANSY S Fluen t, you c an op en da tabases of cust om ma terials sa ved as .scm files and use them t o define the ma terials in y our pr oblem setup .The ma terial da ta must b e pr epar ed in a sp ecific f ormat as sho wn in the e xamples tha t follow. Examples: The pr escr ibed f ormat for sa ving ma terial pr operties inf ormation is sho wn her e for air and aluminum. These files c an b e created in a t ext edit or and sa ved with a .scm extension. ((air fluid (chemical-formula . #f) (density (constant . 1.225) (premixed-combustion 1.225 300)) (specific-heat (constant . 1006.43)) (thermal-conductivity (constant . 0.0242)) (viscosity (constant . 1.7894e-05) (sutherland 1.7894e-05 273.11 110.56) (power-law 1.7894e-05 273.11 0.666)) (molecular-weight (constant . 28.966)) ) (aluminum solid (chemical-formula . al) (density (constant . 2719)) (specific-heat (constant . 871)) (thermal-conductivity (constant . 202.4)) (formation-entropy (constant . 164448.08)) )) To selec t a user-defined da tabase , click the User-D efined D atabase ... butt on in the Create/Edit M a- terials D ialog Box (p.3386 ).This will op en the Open D atabase D ialog Box (p.3397 ). Figur e 8.4: Op en D atabase D ialo g Box Click the Browse... butt on, selec t the da tabase in The S elec t File D ialog Box (p.569) tha t op ens and click OK. Click OK in the Open D atabase D ialog Box (p.3397 ) to op en the User-D efined D atabase M a- terials D ialog Box (p.3398 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1088Physical Properties8.1.4.2. Viewing M aterials in a User -Defined D atabase When an e xisting user-defined da tabase is op ened , the ma terials pr esen t in the da tabase ar e list ed in the User-D efined D atabase M aterials D ialog Box (p.3398 ).You c an selec t the ma terial t ype in the Material Type drop-do wn list and the c orresponding ma terials will app ear in the User-D efined F luid Materials,User-D efined S olid M aterials or other similar ly named list. The name of the list will b e the same as the ma terial t ype you selec ted. Figur e 8.5: User-D efined D atabase M aterials D ialo g Box The pr operties of the selec ted ma terial will app ear in the Properties sec tion of the dialo g box.This dialo g box is similar t o the Fluen t Database M aterials D ialog Box (p.3396 ) in func tion and op eration. 8.1.4.3. Copying M aterials fr om a User -Defined D atabase The pr ocedur e for c opying a ma terial fr om a cust om da tabase is as f ollows: 1.In the Create/Edit M aterials D ialog Box (p.3386 ), click the User-D efined D atabase ... butt on and op en the database fr om which y ou w ant to copy the ma terial. 1089Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Defining M aterials2.In the User-D efined D atabase M aterials D ialog Box (p.3398 ) of the selec ted da tabase , selec t the t ype of material (fluid ,solid , and so on) in the Material Type drop-do wn list. 3.In the User-D efined F luid M aterials list,User-D efined S olid M aterials list, or other similar ly named list (the list ’s name will b e the same as the ma terial type you selec ted in the pr evious st ep), cho ose the materials y ou w ant to copy by click ing on them. The pr operties ar e displa yed in the Properties area. 4.If you w ant to check the ma terial pr operties, use the scr oll bar t o the r ight of the Properties area to scr oll through the list ed it ems . 5.Click the Copy butt on. The selec ted ma terials and their pr operties will b e copied fr om the da tabase in to your lo cal list , and y our c opy of the pr operties will no w b e displa yed in the Materials Task P age (p.3384 ) and under the Materials tree br anch. To copy all the mat erials fr om the database in one st ep, click the butt on ( ) ne xt to User -Defined Materials title and click Copy. If a ma terial with the same name is alr eady defined in the c ase, ANSY S Fluen t will pr ompt y ou t o enter a new name and f ormula in the New M aterial N ame D ialog Box (p.3401 ). Enter a new name and f ormula in the r espective fields and click OK to mak e a lo cal copy of the ma terial. Figur e 8.6: New M aterial N ame D ialo g Box 6.Close the User-D efined D atabase M aterials D ialog Box (p.3398 ). After copying a ma terial fr om the da tabase , you ma y mo dify its pr operties or change its name , as descr ibed ear lier in Using the Create/Edit M aterials Dialog Box (p.1081 ).The ma terial in the da tabase will not b e aff ected b y an y changes y ou mak e to your lo cal copy of the ma terial. 8.1.4.4. Copying M aterials fr om the C ase t o a User -Defined D atabase The pr ocedur e for c opying a ma terial t o a cust om da tabase is as f ollows: 1.In the Create/Edit M aterials D ialog Box (p.3386 ), click User-D efined D atabase .... 2.In the Open D atabase D ialog Box (p.3397 ), selec t the da tabase t o which y ou w ant to copy the ma terial. If you w ant to create a new da tabase , enter the name of the new da tabase in the Database N ame field and click OK. A Question D ialog Box (p.569) will ask y ou t o confir m if y ou w ant to create a new file . Click Yes to confir m. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1090Physical Properties3.In the User-D efined D atabase M aterials D ialog Box (p.3398 ), click Copy M aterials F rom C ase.....This will open the Copy Case M aterial D ialog Box (p.3399 ). Figur e 8.7: Copy Case M aterial D ialo g Box a.In the Copy Case M aterial D ialog Box (p.3399 ), selec t the ma terials tha t you w ant to copy. To selec t all the mat erials, click the shaded ic on t o the r ight of the Case M aterials title . Click ing on the unshaded ic on will deselec t the selec tions in the list . b.Click Copy and close the dialo g box. Note Do not c opy ma terials one b y one .This will r esult in pr eviously c opied ma terials getting o verwritten b y the new ones . Inst ead, selec t all the ma terials t o be copied and click Copy. 8.1.4.5. Mo difying P roperties of an E xisting M aterial You c an mo dify the pr operties of an e xisting ma terial and use the mo dified ma terial in the pr oblem setup and sa ve the mo dified ma terial t o the ma terials da tabase . 1.In the Create/Edit M aterials D ialog Box (p.3386 ), click the User-D efined D atabase ... butt on and op en the database tha t you w ant to use . a.In the User-D efined D atabase M aterials D ialog Box (p.3398 ) of the selec ted da tabase , selec t the t ype of ma terial (fluid ,solid , and so on) in the Material Type drop-do wn list. b.In the User-D efined F luid M aterials list,User-D efined S olid M aterials list, or other similar ly named list (the name of the list will b e the same as the ma terial type you selec ted in the pr evious st ep), selec t the ma terial to be mo dified . c.Click Edit... to op en the Material P roperties D ialog Box (p.3399 ). i.In the Materials P roperties list, selec t the pr operty to be mo dified and click Edit... to op en the Edit P roperty Metho ds D ialog Box (p.3400 ). 1091Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Defining M aterialsii.Selec t the metho d to be mo dified in the Material P roperties list of the Edit P roperty Metho ds Dialog Box (p.3400 ) and click Edit... under Edit P roperties , in or der t o mo dify the pr operties. iii.Make the changes in the c orresponding metho d dialo g box and click OK. iv.Click Apply in the Material P roperties D ialog Box (p.3399 ). d.To use the mo dified ma terial in the pr oblem setup , click Copy in the User-D efined D atabase M aterials Dialog Box (p.3398 ). e.To sa ve the mo dified ma terial to the da tabase , click Save and close the dialo g box. 8.1.4.6. Creating a N ew M aterials D atabase and M aterials Using the Create/Edit M aterials D ialog Box (p.3386 ), you c an cr eate a new ma terials da tabase , copy materials t o this da tabase , and also cr eate new ma terials fr om scr atch.The pr ocedur e for cr eating a new da tabase and add new ma terials t o the da tabase is as f ollows: 1.In the Materials Task P age (p.3384 ), click User-D efined D atabase .... 2.In the Open D atabase D ialog Box (p.3397 ), enter the name of the da tabase tha t you ar e creating and click OK. 3.A dialo g box will app ear ask ing y ou c onfir m the cr eation of a new file . Click Yes to confir m. This will op en a blank User-Defined D atabase Mat erials D ialo g Box (p.3398 ) (Figur e 8.8: User-Defined Database Mat erials D ialo g Box: Blank (p.1092 )). Figur e 8.8: User-D efined D atabase M aterials D ialo g Box: Blank Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1092Physical Properties4.Click New... in the User-D efined D atabase M aterials D ialog Box (p.3398 ).This will op en a blank Material Properties dialo g box. Figur e 8.9: Material P roperties D ialo g Box: Blank a.In the Material P roperties D ialog Box (p.3399 ), under Types, selec t the ma terial type.You c an selec t from fluid ,solid ,iner t-par ticle ,droplet-par ticle ,combusting-par ticle , and mix ture materials. b.Enter the name and f ormula (if r equir ed) of the ma terial tha t you ar e creating in the Name and For- mula fields . c.Depending on the t ype of ma terial selec ted in the Types list, properties applic able t o tha t ma terial type will app ear in the Available P roperties list. Selec t the pr operties tha t are applic able f or the material tha t you ar e defining b y click ing on them. d.Click the butt on t o mo ve these pr operties t o the Material P roperties list on the r ight and click Apply .You c an use the butt on t o mo ve the pr operty from the Material P roperties list t o the Available P roperties list. 5.To edit the par amet ers tha t define a pr operty, selec t the pr operty in the Material P roperties list and click Edit....This op ens the Edit P roperty Metho ds D ialog Box (p.3400 ). 1093Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Defining M aterialsFigur e 8.10: Edit P roperty M etho ds D ialo g Box a.The metho ds tha t can b e used t o define the selec ted pr operty are list ed in the Available P roperties list.You c an selec t one or mor e metho ds and sp ecify them f or the ma terial tha t you ar e defining , by selec ting and mo ving them t o the Material P roperties list. b.To mo dify each of these metho ds, you c an selec t the metho d in the Edit P roperties drop-do wn list and click Edit....This will op en the c orresponding pr operty dialo g box, wher e you c an mo dify the paramet ers used b y the pr operty metho d. Refer to Defining P roperties U sing Temp erature-Dependen t Functions (p.1095 ) to Real G as M odels (p.1154 ) for details of these pr operties, metho ds used t o define the pr operties and the par amet ers f or each metho d. c.Click OK in the Edit P roperty Metho ds D ialog Box (p.3400 ). 6.Click Apply in the Material P roperties D ialog Box (p.3399 ). 7.Click Save in the User-D efined D atabase M aterials D ialog Box (p.3398 ) to sa ve the changes t o the new materials da tabase . Similar ly, you c an also app end new ma terials and click sa ve to app end these ma terials t o the e xisting database . 8.1.4.7. Deleting M aterials fr om a D atabase To delet e a ma terial fr om a da tabase , click the User-D efined D atabase butt on in the Open D atabase Dialog Box (p.3397 ). Selec t the da tabase and click OK in the Open D atabase D ialog Box (p.3397 ). Selec t the Material Type and the ma terials tha t you w ant to delet e in the User-D efined M aterials list and click Delet e. Click Save to sa ve the da tabase . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1094Physical Properties8.2. Defining P roperties U sing Temp erature-D ependen t Func tions Material pr operties c an b e defined as func tions of t emp erature. For most pr operties, you c an define a polynomial, piec ewise-linear , or piec ewise-p olynomial func tion of t emp erature. •polynomial: (8.1) •piec ewise-linear : (8.2) wher e and is the numb er of segmen ts •piec ewise-p olynomial: (8.3) In the equa tions ab ove, is the pr operty. Imp ortant If you define a p olynomial or piec ewise-p olynomial func tion of t emp erature, the t emp erature in the func tion is alw ays in units of Kelvin or R ankine. If you use C elsius or Kelvin as the temp erature unit , then p olynomial c oefficien t values must b e en tered in t erms of Kelvin. If you use F ahrenheit or R ankine as the t emp erature unit , enter the v alues in t erms of R ankine. Some pr operties ha ve additional func tions a vailable and f or some only a subset of these thr ee func tions can b e used . See the sec tion on the pr operty in question t o det ermine which t emp erature-dep enden t func tions y ou c an use . For additional inf ormation, see the f ollowing sec tions: 8.2.1. Inputs f or P olynomial F unctions 8.2.2. Inputs f or P iecewise-Linear F unctions 8.2.3. Inputs f or P iecewise-P olynomial F unctions 8.2.4. Check ing and M odifying Existing P rofiles 8.2.1. Inputs f or P olynomial F unc tions To define a p olynomial func tion of t emp erature for a ma terial pr operty, do the f ollowing: 1.In the Create/Edit M aterials D ialog Box (p.3386 ), cho ose polynomial in the dr op-do wn list t o the r ight of the pr operty name (f or e xample ,Densit y).The Polynomial P rofile D ialog Box (p.3402 ) (Figur e 8.11: The Polynomial P rofile D ialog Box (p.1096 )) will op en aut oma tically. 1095Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Defining P roperties U sing Temp erature-Dependen t FunctionsFigur e 8.11: The P olynomial P rofile D ialo g Box Since this is a mo dal dialo g box, the solv er will not allo w you t o do an ything else un til you p erform the f ollowing st eps. a.Specify the numb er of Coefficien ts up t o 8 c oefficien ts ar e available .The numb er of c oefficien ts defines the or der of the p olynomial. The default of 1 defines a p olynomial of or der 0. The pr operty will b e constan t and equal t o the single c oefficien t . An input of 2 defines a p olynomial of or der 1 and the pr operty will v ary linear ly with t emp erature and so on. b.Define the c oefficien ts. Coefficien ts 1,2,3,... correspond t o , , ,... in Equa tion 8.1 (p.1095 ).The dialo g box in Figur e 8.11: The P olynomial P rofile D ialog Box (p.1096 ) sho ws the inputs f or the f ollowing func tion: (8.4) Imp ortant To ensur e the r obustness of simula tions when using p olynomials t o sp ecify ma terial pr operty, set the solution limits so tha t the v alues r etur ned b y the p olynomial e xpression ar e ph ysically valid. For e xample , when the densit y of a ma terial is sp ecified as a func tion of t emp erature using a p olynomial e xpression, set the pr oper limits on the t emp erature range so tha t the densit y is alw ays non-nega tive. For mor e inf ormation on setting solution limits see Setting Solution Limits (p.2599 ). Also, not e the r estriction on the units f or temp erature, as descr ibed in the pr evious sec tion. 8.2.2. Inputs f or P iecewise-Linear F unc tions To define a piec ewise-linear func tion of t emp erature for a ma terial pr operty, do the f ollowing: 1.In the Create/Edit M aterials D ialog Box (p.3386 ), cho ose piec ewise-linear in the dr op-do wn list t o the r ight of the pr operty name (f or e xample ,Visc osit y).The Piecewise-Linear P rofile D ialog Box (p.3403 ) (Fig- ure 8.12: The P iecewise-Linear P rofile D ialog Box (p.1097 )) will op en aut oma tically. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1096Physical PropertiesFigur e 8.12: The P iecewise-Linear P rofile D ialo g Box Since this is a mo dal dialo g box, the sol ver will not allo w y ou t o do anything else until y ou p erform the follo wing st eps. a.Set the numb er of Points defining the piec ewise distr ibution. b.Under Data P oints, enter the da ta pairs f or each p oint. First en ter the indep enden t and dep enden t variable v alues f or Point 1, then incr ease the Point numb er and en ter the appr opriate values f or each additional pair of v ariables .The pairs of p oints must b e supplied in the or der of incr easing v alue of temp erature.The solv er will not sort them f or y ou. A maximum of 50 piec ewise p oints can b e defined for each pr operty.The dialo g box in Figur e 8.12: The P iecewise-Linear P rofile D ialog Box (p.1097 ) sho ws the final inputs f or the pr ofile depic ted in Figur e 8.13: Piecewise-Linear D efinition of Viscosity as a Function of Temp erature (p.1097 ). Imp ortant If the t emp erature exceeds the maximum Temp erature ( ) you ha ve sp ecified for the pr ofile , ANSY S Fluen t will use the Value corresponding t o . If the t emp er- ature falls b elow the minimum Temp erature ( ) specified f or y our pr ofile , ANSY S Fluen t will use the Value corresponding t o . Figur e 8.13: Piecewise-Linear D efinition of Visc osit y as a F unc tion of Temp erature 1097Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Defining P roperties U sing Temp erature-Dependen t Functions8.2.3. Inputs f or P iecewise-P olynomial F unc tions To define a piec ewise-p olynomial func tion of t emp erature for a ma terial pr operty, follow these st eps: 1.In the Create/Edit M aterials D ialog Box (p.3386 ), cho ose piec ewise-p olynomial in the dr op-do wn list t o the r ight of the pr operty name (f or e xample ,Cp).The Piecewise-P olynomial P rofile D ialog Box (p.3404 ) (Figur e 8.14: The P iecewise-P olynomial P rofile D ialog Box (p.1098 )) will op en aut oma tically. Since this is a modal dialo g box, first p erform the f ollowing st eps. Figur e 8.14: The P iecewise-P olynomial P rofile D ialo g Box 2.Specify the numb er of Ranges . For the e xample of Equa tion 8.5 (p.1098 ), two ranges of t emp eratures ar e defined: (8.5) You ma y define up t o thr ee r anges .The r anges must b e supplied in the or der of incr easing v alue of temp erature.The solv er will not sor t them f or y ou. 3.For the first r ange ( Range = 1), specify the Minimum and Maximum temp eratures, and the numb er of Coefficien ts. (Up to eigh t coefficien ts ar e available .) The numb er of c oefficien ts defines the or der of the polynomial. The default of 1 defines a p olynomial of or der 0. The pr operty will b e constan t and equal t o the single c oefficien t . An input of 2 defines a p olynomial of or der 1. The pr operty will v ary linear ly with temp erature and so on. 4.Define the c oefficien ts. Coefficien ts 1,2,3,... correspond t o , , ,... in Equa tion 8.3 (p.1095 ).The dialo g box in Figur e 8.14: The P iecewise-P olynomial P rofile D ialog Box (p.1098 ) sho ws the inputs f or the first r ange of Equa tion 8.5 (p.1098 ). 5.Increase the v alue of Range and en ter the Minimum and Maximum temp eratures, numb er of Coefficien ts, and the Coefficien ts ( , , ,...) f or the ne xt range . Repeat if ther e is a thir d range . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1098Physical Properties8.2.4. Check ing and M odifying E xisting P rofiles If you w ant to check or change the c oefficien ts, data pairs , or r anges f or a pr eviously-defined pr ofile , click the Edit... butt on t o the r ight of the pr operty name .The appr opriate dialo g box will op en, and you c an check or mo dify the inputs as desir ed. Imp ortant In the Fluen t Database M aterials D ialog Box (p.3396 ), you c annot edit the pr ofiles , but y ou can e xamine them b y click ing on the View... butt on (inst ead of the Edit... butt on.) 8.3. Densit y ANSY S Fluen t provides se veral options f or definition of the fluid densit y: •constan t densit y •temp erature and/or c omp osition-dep enden t densit y •pressur e-dep enden t densit y Each of these input options and the go verning ph ysical mo dels ar e explained in the f ollowing sec tions . In all c ases , you will define the Densit y in the Create/Edit M aterials D ialog Box (p.3386 ). Setup → Materials Note For tr ansien t, variable-densit y flo ws tha t use the pr essur e-based solv er, you ma y reach c on- vergenc e fast er if y ou sp ecify tha t the mo del equa tions ar e solv ed in an optimal or der. For details , see Equa tion Or der (p.2580 ). For additional inf ormation, see the f ollowing sec tions: 8.3.1. Defining D ensit y for Various F low Regimes 8.3.2. Input of C onstan t Densit y 8.3.3. Inputs f or the B oussinesq A pproxima tion 8.3.4. Compr essible Liquid D ensit y Metho d 8.3.5. Densit y as a P rofile F unction of Temp erature 8.3.6. Incompr essible Ideal G as La w 8.3.7. Ideal G as La w for C ompr essible F lows 8.3.8. Comp osition-D ependen t Densit y for M ultic omp onen t Mixtures 8.3.1. Defining D ensit y for Various F low Regimes The selec tion of densit y in ANSY S Fluen t is v ery imp ortant. Set the densit y relationship based on y our flow regime . •For compr essible flo ws, the ideal gas la w is the appr opriate densit y relationship . •For inc ompr essible flo ws, you ma y cho ose one of the f ollowing metho ds: 1099Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Densit y–Constan t densit y, if you do not w ant densit y to be a func tion of t emp erature. –The inc ompr essible ideal gas la w, when pr essur e variations ar e small enough tha t the flo w is fully inc om- pressible but y ou w ant to use the ideal gas la w to express the r elationship b etween densit y and t emp er- ature (for e xample , for a na tural convection pr oblem). –Densit y as a p olynomial, piec ewise-linear , or piec ewise-p olynomial func tion of t emp erature, when the densit y is a func tion of t emp erature only , as in a na tural convection pr oblem. –The B oussinesq mo del, for na tural convection pr oblems in volving small changes in t emp erature. –The c ompr essible liquid densit y metho d allo ws you t o mo del c ompr essible liquids under high pr essur es. 8.3.1.1. Mixing D ensit y Relationships in Multiple-Z one Mo dels If your mo del has multiple fluid z ones tha t use diff erent ma terials, you should b e aware of the f ollowing: •For calcula tions with the pr essur e-based solv er tha t do not use one of the gener al multiphase mo dels (Solution S trategies f or M ultiphase M odeling (p.2261 )), the c ompr essible ideal gas la w cannot b e mix ed with an y other densit y metho ds.This means tha t if the c ompr essible ideal gas la w is used f or one ma terial, it must b e used f or all ma terials. This r estriction do es not apply t o the densit y-based solv ers. •There is only one sp ecified op erating pr essur e and one sp ecified op erating t emp erature.This means tha t if you ar e using the ideal gas la w for mor e than one ma terial, the y will shar e the same op erating pr essur e. If you ar e using the B oussinesq mo del f or mor e than one ma terial, the y will shar e the same op erating temp erature. 8.3.2. Input of C onstan t Densit y If you w ant to define the densit y of the fluid as a c onstan t, selec t constan t in the Densit y drop-do wn list under Properties in the Create/Edit M aterials D ialog Box (p.3386 ). Enter the v alue of densit y for the material. For the default fluid (air), the densit y is 1.225 k g/ . 8.3.3. Inputs f or the B oussinesq A ppr oxima tion To enable the B oussinesq appr oxima tion f or densit y, cho ose boussinesq from the Densit y drop-do wn list in the Create/Edit M aterials D ialog Box (p.3386 ) and sp ecify a c onstan t value f or Densit y.You will also need t o set the Thermal E xpansion C oefficien t, as w ell as r elevant op erating c onditions , as de- scribed in The B oussinesq M odel (p.1476 ). 8.3.4. Compr essible Liquid D ensit y M etho d The c ompr essible liquid tr eatmen t enables y ou t o mo del liquid c ompr essibilit y under high pr essur e applic ations . Fluen t mo dels c ompr essible liquids using the Tait equa tion of sta te, which establishes a nonlinear r elationship b etween densit y and pr essur e under isother mal c onditions . The c ompr essible liquid tr eatmen t also helps in r educing unph ysical pr essur e spik es tha t app ear in moving and d ynamic mesh applic ations , esp ecially dur ing solid-fluid in teractions . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1100Physical PropertiesThe Tait equa tion c an b e represen ted in t erms of pr essur e and densit y using the f ollowing r elationship: (8.6) wher e, and are coefficien ts tha t can b e det ermined b y assuming tha t the bulk mo dulus is a linear func tion of pr essur e.The v alues of c oefficien ts and are based on the r eference sta te values of pressur e, densit y, and bulk mo dulus . The simplified f orm of the Tait equa tion c an b e wr itten as: (8.7) wher e, (8.8) and (8.9) wher e, = R eference liquid pr essur e (A bsolut e) = R eference liquid densit y (D ensit y at reference pr essur e, ) = R eference bulk mo dulus (B ulk mo dulus a t reference pr essur e, ) = D ensit y exponen t = Liquid pr essur e (A bsolut e) = Liquid densit y at pressur e, = B ulk mo dulus a t pressur e, The densit y ratio is limit ed t o the r ange: (8.10) wher e, = M inimum densit y ratio limit , when = M aximum densit y ratio limit , when The sp eed of sound , , is c alcula ted as: (8.11) Note You c an p ostpr ocess the sp eed of sound f or c ompr essible liquid ma terials. For multiphase models , sound-sp eed p ostpr ocessing is a vailable a t mix ture and/or phase le vel, dep ending on the mo del selec ted. Sound-sp eed p ostpr ocessing is also enabled if y ou descr ibe the speed of sound f or a user-defined densit y. 1101Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Densit y8.3.4.1. Compr essible Liquid Inputs Selec t the compressible-liquid under Densit y in the Create/Edit M aterials panel as seen in Figur e 8.15: Compr essible Liquid M aterials S etting (p.1102 ). Figur e 8.15: Compr essible Liquid M aterials S etting In the Compr essible Liquid dialo g box you need t o sp ecify v alues f or the f ollowing settings: •Reference Pressur e •Reference Densit y •Reference Bulk M odulus •Densit y Exp onen t •Maximum D ensit y Ratio Limit •Minimum D ensit y Ratio Limit Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1102Physical PropertiesFigur e 8.16: Compr essible Liquid D ensit y Settings P anel Note •ANSY S Fluen t aut oma tically fills user input v alues f or certain ma terials based on op en lit erature. If data is not a vailable F luen t will fill in v alues of z ero.Therefore, you must v erify tha t suitable values ar e en tered f or y our applic ation. •When F luen t aut oma tically fills in v alues , the default v alue of the densit y exponen t is set close to the v alue f or w ater-liquid . •The v alue f or the densit y exponen t is gener ally f ound b y calibr ating against da ta for densit y, pressur e, bulk mo dulus , and sp eed of sound . If the v alue is unk nown, it is r ecommended tha t you use a v alue of 1, which c orresponds t o a linear r elationship b etween densit y and pr essur e. You c an set the c ompr essible-liquid densit y metho d using the f ollowing t ext command: define → materials → change-create In the t ext command in terface, set the change Density? option t o yes , and set new method [constant] to compressible-liquid as sho wn b elow: /define/materials> change-create material-name> water-liquid material name [water-liquid] water-liquid is a fluid change Density? [no] yes Density methods: (constant ideal-gas incompressible-ideal-gas real-gas-soave-redlich-kwong real-gas-peng-robinson real-gas-aungier-redlich-kwong real-gas-redlich-kwong boussinesq piecewise-linear piecewise-polynomial polynomial compressible-liquid user-defined) new method [constant] compressible-liquid Reference Pressure (pascal) [101325] Reference Density (kg/m3) [998.2000000000001] Reference Bulk Modulus (pascal) [2200000000] Density Exponent [7.15] Maximum Density Ratio Limit [1.1] Minimum Density Ratio Limit [0.9] 1103Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Densit y8.3.4.2. Compr essible Liquid D ensit y Metho d Availabilit y The c ompr essible liquid densit y metho d is a vailable with fluid ma terials or with c omp onen ts of a mixture ma terial ha ving the densit y metho d set t o volume-weighted-mixing-law for b oth single and multiphase c ases . This metho d is not a vailable with the densit y-based solv er. 8.3.5. Densit y as a P rofile F unc tion of Temp erature If you ar e mo deling a pr oblem tha t involves hea t transf er, you c an define the densit y as a func tion of temp erature.Three t ypes of func tions ar e available: •piec ewise-linear : (8.12) •piec ewise-p olynomial: (8.13) •polynomial: (8.14) For one of the these metho ds, selec t piec ewise-linear ,piec ewise-p olynomial , or polynomial in the Densit y drop-do wn list. You c an en ter the da ta pairs ( ), ranges and c oefficien ts, or c oefficien ts that descr ibe these func tions using the Create/Edit M aterials D ialog Box (p.3386 ), as descr ibed in Defining Properties U sing Temp erature-Dependen t Functions (p.1095 ). 8.3.6. Incompr essible Ideal G as L aw In ANSY S Fluen t, if y ou cho ose t o define the densit y using the ideal gas la w for an inc ompr essible flow, the solv er will c omput e the densit y as (8.15) wher e, = the univ ersal gas c onstan t = the molecular w eigh t of the gas = the op erating pr essur e In this f orm, the densit y dep ends only on the op erating pr essur e and not on the lo cal relative pr essur e field . 8.3.6.1. Densit y Inputs for the Inc ompr essible Ideal G as L aw The inputs f or the inc ompr essible ideal gas la w ar e as f ollows: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1104Physical Properties1.Enable the ideal gas la w for an inc ompr essible fluid b y cho osing incompr essible-ideal-gas from the drop-do wn list t o the r ight of Densit y in the Create/Edit M aterials D ialog Box (p.3386 ). Specify the inc ompr essible ideal gas la w individually f or each ma terial tha t you w ant to use it f or. See Comp osition-D ependen t Densit y for M ultic omp onen t Mixtures (p.1106 ) for inf ormation on specifying the inc ompr essible ideal gas la w for mix tures. 2.Set the op erating pr essur e by defining the Operating P ressur e in the Operating C onditions D ialog Box (p.3470 ). Setup → Cell Z one C onditions → Operating C onditions ... Imp ortant By default , operating pr essur e is set t o 101325 P a.The input of the op erating pr essur e is of gr eat imp ortanc e when y ou ar e computing densit y with the ideal gas la w. See Operating P ressur e (p.1152 ) for recommenda tions on setting appr opriate values f or the operating pr essur e. 3.Set the molecular w eigh t of the homo geneous or single-c omp onen t fluid (if no chemic al sp ecies tr ansp ort equa tions ar e to be solv ed), or the molecular w eigh ts of each fluid ma terial (sp ecies) in a multic omp onen t mixture. For each fluid ma terial, enter the v alue of the Molecular Weigh t in the Create/Edit M aterials Dialog Box (p.3386 ). 8.3.7. Ideal G as L aw for C ompr essible F lows For c ompr essible flo ws, the gas la w is as f ollowing: (8.16) wher e, = the lo cal relative (or gauge) pr essur e pr edic ted b y ANSY S Fluen t = the op erating pr essur e 8.3.7.1. Densit y Inputs for the Ideal G as L aw for C ompr essible F lows The inputs f or the ideal gas la w ar e as f ollows: 1.Enable the ideal gas la w for a c ompr essible fluid b y cho osing ideal-gas from the dr op-do wn list t o the right of Densit y in the Create/Edit M aterials D ialog Box (p.3386 ). Specify the ideal gas la w individually f or each ma terial tha t you w ant to use it f or. See Comp osition- Dependen t Densit y for M ultic omp onen t Mixtures (p.1106 ) for inf ormation on sp ecifying the ideal gas la w for mix tures. 2.Set the op erating pr essur e by defining the Operating P ressur e in the Operating C onditions D ialog Box (p.3470 ). 1105Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Densit ySetup → Cell Z one C onditions → Operating C onditions ... Imp ortant The input of the op erating pr essur e is of gr eat imp ortanc e when y ou ar e computing densit y with the ideal gas la w.Equa tion 8.16 (p.1105 ) not es tha t the op erating pr essur e is added t o the r elative pr essur e field c omput ed b y the solv er, yielding the absolut e static pr essur e. See Operating P ressur e (p.1152 ) for recommenda tions on setting appr o- priate values f or the op erating pr essur e. By default , operating pr essur e is set t o 101325 Pa. 3.Set the molecular w eigh t of the homo geneous or single-c omp onen t fluid (if no chemic al sp ecies tr ansp ort equa tions ar e to be solv ed), or the molecular w eigh ts of each fluid ma terial (sp ecies) in a multic omp onen t mixture. For each fluid ma terial, enter the v alue of the Molecular Weigh t in the Create/Edit M aterials Dialog Box (p.3386 ). 8.3.8. Comp osition-D ependen t Densit y for M ultic omp onen t Mixtures If you ar e solving sp ecies tr ansp ort equa tions , set pr operties f or the mix ture ma terial and f or the c on- stituen t fluids (sp ecies), as descr ibed in detail in Defining P roperties f or the M ixture and I ts C onstituen t Species (p.1629 ).To define a c omp osition-dep enden t densit y for a mix ture, do the f ollowing: 1.Selec t the densit y metho d: •For non-ideal-gas mix tures, selec t the volume-w eigh ted-mixing-la w metho d for the mix ture ma terial in the dr op-do wn list t o the r ight of Densit y in the Create/Edit M aterials D ialog Box (p.3386 ). •If you ar e mo deling c ompr essible flo w, selec t ideal-gas for the mix ture ma terial in the dr op-do wn list t o the r ight of Densit y in the Create/Edit M aterials D ialog Box (p.3386 ). •If you ar e mo deling inc ompr essible flo w using the ideal gas la w, selec t incompr essible-ideal-gas for the mix ture ma terial in the Densit y drop-do wn list in the Create/Edit M aterials D ialog Box (p.3386 ). •If you ha ve a user-defined func tion tha t you w ant to use t o mo del the densit y, you c an cho ose either the user-defined metho d or the user-defined-mixing-la w metho d for the mix ture ma terial in the drop-do wn list. The only diff erence between the user-defined-mixing-la w and the user-defined option f or sp e- cifying densit y, visc osity and ther mal c onduc tivit y of mix ture ma terials, is tha t with the user-defined- mixing-la w option, the individual pr operties of the sp ecies ma terials c an also b e sp ecified . (Note that only the c onstan t, the p olynomial metho ds and the user-defined metho ds ar e available .) 2.Click Change/C reate. 3.If you ha ve selec ted volume-w eigh ted-mixing-la w, define the densit y for each of the fluid ma terials tha t mak e up the mix ture.You ma y define c onstan t or c ompr essible-liquid or (if applic able) t emp erature-de- penden t densities f or the individual sp ecies . 4.If you selec ted user-defined-mixing-la w, define the densit y for each of the fluid ma terials tha t mak e up the mix ture.You ma y define c onstan t, or (if applic able) t emp erature-dep enden t densities , or user-defined densities f or the individual sp ecies . More inf ormation on defining pr operties with user-defined func tions can b e found in the Fluen t Customiza tion M anual . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1106Physical PropertiesIf you ar e mo deling a non-ideal-gas mix ture, ANSY S Fluen t will c omput e the mix ture densit y as (8.17) wher e is the mass fr action and is the densit y of sp ecies . For c ompr essible flo ws, the gas la w has the f ollowing f orm: (8.18) wher e, = the lo cal relative (or gauge) pr essur e pr edic ted b y ANSY S Fluen t = the univ ersal gas c onstan t = the mass fr action of sp ecies = the molecular w eigh t of sp ecies = the op erating pr essur e In ANSY S Fluen t, if y ou cho ose t o define the densit y using the ideal gas la w for an inc ompr essible flow, the solv er will c omput e the densit y as (8.19) wher e, = the univ ersal gas c onstan t = the mass fr action of sp ecies = the molecular w eigh t of sp ecies = the op erating pr essur e 8.4. Visc osit y ANSY S Fluen t provides se veral options f or definition of the fluid visc osity: •constan t visc osity •temp erature-dep enden t and/or c omp osition-dep enden t visc osity •kinetic theor y •non-N ewtonian visc osity •user-defined func tion 1107Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.ViscosityEach of these input options and the go verning ph ysical mo dels ar e detailed in this sec tion. (User-defined func tions ar e descr ibed in the Fluen t Customiza tion M anual ). In all c ases , define the Visc osit y in the Create/Edit M aterials D ialog Box (p.3386 ). Setup → Materials Viscosities ar e input as d ynamic visc osity ( ) in units of k g/m-s in SI units or /ft-s in B ritish units . ANSY S Fluen t do es not ask f or input of the k inema tic visc osity ( ). For additional inf ormation, see the f ollowing sec tions: 8.4.1. Input of C onstan t Viscosity 8.4.2. Viscosity as a F unction of Temp erature 8.4.3. Defining the Viscosity Using K inetic Theor y 8.4.4. Comp osition-D ependen t Viscosity for M ultic omp onen t Mixtures 8.4.5. Viscosity for N on-N ewtonian F luids 8.4.1. Input of C onstan t Visc osit y If you w ant to define the visc osity of y our fluid as a c onstan t, selec t constan t in the Visc osit y drop- down list in the Create/Edit M aterials D ialog Box (p.3386 ), and en ter the v alue of visc osity for the fluid . For the default fluid (air), the visc osity is kg/m-s . 8.4.2. Visc osit y as a F unc tion of Temp erature If you ar e mo deling a pr oblem tha t involves hea t transf er, you c an define the visc osity as a func tion of temp erature. Five types of func tions ar e available . •piec ewise-linear : (8.20) •piec ewise-p olynomial: (8.21) •polynomial: (8.22) •Suther land ’s law •power la w Imp ortant The p ower la w descr ibed her e is diff erent from the non-N ewtonian p ower la w descr ibed in Viscosity for N on-N ewtonian F luids (p.1112 ). For one of the first thr ee, selec t piec ewise-linear ,piec ewise-p olynomial ,polynomial in the Visc osit y drop-do wn list and then en ter the da ta pairs ( ), ranges and c oefficien ts, or c oefficien ts tha t descr ibe Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1108Physical Propertiesthese func tions Defining P roperties U sing Temp erature-Dependen t Functions (p.1095 ). For Suther land ’s law or the p ower la w, cho ose suther land or power-la w respectively in the dr op-do wn list and en ter the par amet ers. 8.4.2.1. Sutherland Visc osit y Law Suther land ’s visc osity law result ed fr om a k inetic theor y by Suther land (1893) using an idealiz ed in ter- molecular-f orce potential. The f ormula is sp ecified using t wo or thr ee c oefficien ts. Suther land ’s law with t wo coefficien ts has the f orm (8.23) wher e, = the visc osity in k g/m-s = the sta tic t emp erature in K and = the c oefficien ts For air a t mo derate temp eratures and pr essur es, kg/m-s- , and K. Suther land ’s law with thr ee c oefficien ts has the f orm (8.24) wher e, = the visc osity in k g/m-s = the sta tic t emp erature in K = reference value in k g/m-s = reference temp erature in K = an eff ective temp erature in K (Suther land c onstan t) For air a t mo derate temp eratures and pr essur es, kg/m-s , = 273.11 K, and = 110.56 K. 8.4.2.1.1. Inputs for S utherland’ s Law To use Suther land ’s law, cho ose suther land in the dr op-do wn list t o the r ight of Visc osit y.The Suther land La w D ialog Box (p.3407 ) will op en, and y ou c an en ter the c oefficien ts as f ollows: 1.Selec t the Two Coefficien t Metho d or the Three C oefficien t Metho d. Imp ortant Use SI units if y ou cho ose the t wo-coefficien t metho d. 2.For the Two Coefficien t Metho d, set C1 and C2. For the Three C oefficien t Metho d, set the Referenc e Visc osit y , the Referenc e Temp erature , and the Effective Temp erature . 1109Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Viscosity8.4.2.2. Power-Law Visc osit y Law Another c ommon appr oxima tion f or the visc osity of dilut e gases is the p ower-la w form. For dilut e gases a t mo derate temp eratures, this f orm is c onsider ed t o be sligh tly less accur ate than Suther land ’s law. A power-la w visc osity law with t wo coefficien ts has the f orm (8.25) wher e, = the visc osity in k g/m-s = the sta tic t emp erature in K = a dimensional c oefficien t For air a t mo derate temp eratures and pr essur es, , and . A power-la w visc osity law with thr ee c oefficien ts has the f orm (8.26) wher e, = the visc osity in k g/m-s = the sta tic t emp erature in K = a r eference value in K = a r eference value in k g/m-s For air a t mo derate temp eratures and pr essur es, kg/m-s , K, and . Imp ortant The non-N ewtonian p ower la w for visc osity is descr ibed in Viscosity for N on-N ewtonian Fluids (p.1112 ). 8.4.2.2.1. Inputs for the P ower L aw To use the p ower la w, cho ose power-la w in the dr op-do wn list t o the r ight of Visc osit y.The Power Law D ialog Box (p.3408 ) will op en, and y ou c an en ter the c oefficien ts as f ollows: 1.Selec t the Two Coefficien t Metho d or the Three C oefficien t Metho d. Imp ortant Note tha t you must use SI units if y ou cho ose the t wo-coefficien t metho d. 2.For the Two Coefficien t Metho d, set B and the Temp erature Exponen t . For the Three C oefficien t Metho d, set the Referenc e Visc osit y , the Referenc e Temp erature , and the Temp erature Expo- nen t . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1110Physical Properties8.4.3. Defining the Visc osit y Using K inetic Theor y If you ar e using the ideal gas la w (as descr ibed in Densit y (p.1099 )), you ha ve the option t o define the fluid visc osity using k inetic theor y as (8.27) wher e, is in units of k g/m-s , is in units of Kelvin is in units of A ngstr oms is the molecular w eigh t wher e (8.28) The L ennar d-Jones par amet ers, and , are inputs t o the k inetic theor y calcula tion tha t you supply b y selec ting kinetic-theor y from the dr op-do wn list t o the r ight of Visc osit y in the Create/Edit Materials D ialog Box (p.3386 ).The solv er will use these k inetic theor y inputs in Equa tion 8.27 (p.1111 ) to comput e the fluid visc osity. See Kinetic Theor y Paramet ers (p.1151 ) for details ab out these inputs . 8.4.4. Comp osition-D ependen t Visc osit y for M ultic omp onen t Mixtures If you ar e mo deling a flo w tha t includes mor e than one chemic al sp ecies (multic omp onen t flo w), you have the option t o define a c omp osition-dep enden t visc osity. (Note tha t you c an also define the vis- cosity of the mix ture as a c onstan t value or a func tion of t emp erature.) To define a c omp osition-dep enden t visc osity for a mix ture, follow these st eps: 1.For the mix ture ma terial, cho ose mass-w eigh ted-mixing-la w or, if you ar e using the ideal gas la w for densit y,ideal-gas-mixing-la w in the dr op-do wn list t o the r ight of Visc osit y. If you ha ve a user-defined func tion tha t you w ant to use t o mo del the visc osity, you c an cho ose either the user-defined metho d or the user-defined-mixing-la w metho d for the mix ture ma terial in the dr op-do wn list. 2.Click Change/C reate. 3.Define the visc osity for each of the fluid ma terials tha t mak e up the mix ture.You ma y define c onstan t or (if applic able) t emp erature-dep enden t visc osities f or the individual sp ecies .You ma y also use k inetic theor y for the individual visc osities , or sp ecify a non-N ewtonian visc osity, if applic able . 4.If you selec ted user-defined-mixing-la w, define the visc osity for each of the fluid ma terials tha t mak e up the mix ture.You ma y define c onstan t, or (if applic able) t emp erature-dep enden t visc osities , or user- defined visc osities f or the individual sp ecies . More inf ormation on defining pr operties with user-defined func tions c an b e found in the Fluen t Customiza tion M anual . The only diff erence between the user-defined-mixing-la w and the user-defined option f or sp e- cifying densit y, visc osity and ther mal c onduc tivit y of mix ture ma terials, is tha t with the user-defined- 1111Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Viscositymixing-la w option, the individual pr operties of the sp ecies ma terials c an also b e sp ecified . (Note that only the c onstan t, the p olynomial metho ds and the user-defined metho ds ar e available .) If you ar e using the ideal gas la w, the solv er will c omput e the mix ture visc osity based on k inetic theor y as (8.29) wher e (8.30) and is the mole fr action of sp ecies . For non-ideal gas mix tures, the mix ture visc osity is c omput ed based on a simple mass fr action a verage of the pur e sp ecies visc osities: (8.31) 8.4.5. Visc osit y for N on-N ewtonian F luids For inc ompr essible N ewtonian fluids , the shear str ess is pr oportional t o the r ate-of-def ormation t ensor : (8.32) wher e is defined b y (8.33) and is the visc osity, which is indep enden t of . For some non-N ewtonian fluids , the shear str ess c an similar ly be wr itten in t erms of a non-N ewtonian viscosity : (8.34) In gener al, is a func tion of all thr ee in variants of the r ate-of-def ormation t ensor . However, in the non-N ewtonian mo dels a vailable in ANSY S Fluen t, is c onsider ed t o be a func tion of the shear r ate only . is related t o the sec ond in variant of and is defined as (8.35) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1112Physical Properties8.4.5.1. Temp eratur e Dependent Visc osit y If the flo w is non-isother mal, then the t emp erature dep endenc e on the visc osity can b e included along with the shear r ate dep endenc e. In this c ase, the t otal visc osity consists of t wo par ts and is calcula ted as (8.36) wher e H( T) is the t emp erature dep endenc e, known as the A rrhenius la w. (8.37) wher e is the r atio of the ac tivation ener gy to the ther modynamic c onstan t and is a r eference temp erature for which H( T) = 1. , which is the t emp erature shif t, is set t o 0 b y default , and c orres- ponds t o the lo west t emp erature tha t is ther modynamic ally acc eptable .Therefore and are ab- solut e temp eratures.Temp erature dep endenc e is only included when the ener gy equa tion is enabled . Set the par amet er to 0 when y ou w ant temp erature dep endenc e to be ignor ed, even when the ener gy equa tion is solv ed. ANSY S Fluen t provides f our options f or mo deling non-N ewtonian flo ws: •power la w •Carreau mo del f or pseudo-plastics •Cross mo del •Herschel-B ulkley mo del f or B ingham plastics Imp ortant •Note tha t the mo dels list ed ab ove are not a vailable when mo deling turbulen t flo w. •Note tha t the non-N ewtonian p ower la w descr ibed b elow is diff erent from the p ower la w de- scribed in Power-La w Viscosity La w (p.1110 ). •Non-N ewtonian mo del based on single fluid f ormula tion is a vailable f or the mix ture mo del and it is r ecommended tha t this should b e attached t o the pr imar y phase . Appropriate values f or the input par amet ers f or these mo dels c an b e found in the lit erature (for e x- ample ,[132] (p.4012 )). 8.4.5.2. Power L aw for N on-N ewtonian Visc osit y If you cho ose non-ne wtonian-p ower-la w in the dr op-do wn list t o the r ight of Visc osit y, non-N ewto- nian flo w will b e mo deled acc ording t o the f ollowing p ower la w for the non-N ewtonian visc osity: (8.38) wher e and are input par amet ers. is a measur e of the a verage visc osity of the fluid (the c onsist- ency inde x); is a measur e of the de viation of the fluid fr om N ewtonian (the p ower-la w inde x).The value of det ermines the class of the fluid: 1113Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Viscosity → Newtonian fluid → shear-thick ening (dila tant fluids) → shear-thinning (pseudo-plastics) 8.4.5.2.1. Inputs for the N on-N ewtonian P ower L aw To use the non-N ewtonian p ower la w, cho ose non-ne wtonian-p ower-la w in the dr op-do wn list t o the r ight of Visc osit y.The Non-N ewtonian P ower La w D ialog Box (p.3409 ) will op en, and y ou c an choose b etween Shear R ate D ependen t and Shear R ate and Temp erature D ependen t. Enter the Consist enc y Inde x ,Power-L aw Inde x ,Minimum and Maximum Visc osit y Limit ,Referenc e Temp erature , and Activation E nergy/R, , which is the r atio of the ac tivation ener gy to the ther modynamic c onstan t. 8.4.5.3. The C arreau Mo del for P seudo-P lastics The p ower la w mo del descr ibed in Equa tion 8.38 (p.1113 ) results in a fluid visc osity tha t varies with shear r ate. For , , and f or , , wher e and are, respectively, the upp er and lower limiting v alues of the fluid visc osity. The C arreau mo del a ttempts t o descr ibe a wide r ange of fluids b y the establishmen t of a cur ve-fit t o piec e together func tions f or b oth N ewtonian and shear-thinning ( ) non-N ewtonian la ws. In the Carreau mo del, the visc osity is (8.39) and the par amet ers , , , , and are dep enden t up on the fluid . is the time c onstan t, is the p ower-la w inde x (as descr ibed ab ove for the non-N ewtonian p ower la w), and are, respectively, the z ero- and infinit e-shear visc osities , is the r eference temp erature, and is the r atio of the ac- tivation ener gy to ther modynamic c onstan t.Figur e 8.17: Variation of Viscosity with S hear R ate According to the C arreau M odel (p.1114 ) sho ws ho w visc osity is limit ed b y and at low and high shear r ates. Figur e 8.17: Variation of Visc osit y with S hear R ate According t o the C arreau M odel 8.4.5.3.1. Inputs for the C arreau Mo del To use the C arreau mo del, cho ose carreau in the dr op-do wn list t o the r ight of Visc osit y.The Carreau Model D ialog Box (p.3409 ) will op en, and y ou c an cho ose b etween Shear R ate D ependen t and Shear Rate and Temp erature D ependen t. Enter the Time C onstan t ,Power-L aw Inde x ,Referenc e Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1114Physical PropertiesTemp erature ,Zero Shear Visc osit y ,Infinit e Shear Visc osit y , and Activation E nergy/R . Figur e 8.18: The C arreau M odel D ialo g Box 8.4.5.4. Cross Mo del The C ross mo del f or visc osity is: (8.40) wher e, = z ero-shear-r ate visc osity = na tural time (tha t is, inverse of the shear r ate at which the fluid changes fr om Newtonian t o power-la w b ehavior) = p ower-la w inde x The C ross mo del is c ommonly used t o descr ibe the lo w-shear-r ate behavior of the visc osity. 8.4.5.4.1. Inputs for the C ross Mo del To use the C ross mo del, cho ose cross in the dr op-do wn list t o the r ight of Visc osit y.The Cross Model D ialog Box (p.3411 ) will op en, and y ou c an cho ose b etween Shear R ate D ependen t and Shear Rate and Temp erature D ependen t. Enter the Zero Shear Visc osit y ,Time C onstan t ,Power- Law Inde x ,Referenc e Temp erature , and Activation E nergy/R, , which is the r atio of the activation ener gy to the ther modynamic c onstan t. 1115Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Viscosity8.4.5.5. Herschel-Bulk ley Mo del for B ingham P lastics The p ower la w mo del descr ibed ab ove is v alid f or fluids f or which the shear str ess is z ero when the strain r ate is z ero. Bingham plastics ar e char acterized b y a nonz ero shear str ess when the str ain r ate is zero. (8.41) wher e is the yield str ess: •For , the ma terial remains r igid . •For , the ma terial flo ws as a p ower-la w fluid . The H erschel-B ulkley mo del c ombines the eff ects of B ingham and p ower-la w b ehavior in a fluid . For low str ain r ates ( ), the “rigid” ma terial ac ts lik e a v ery visc ous fluid with visc osity . As the strain r ate incr eases and the yield str ess thr eshold , , is passed , the fluid b ehavior is descr ibed b y a power la w. For (8.42) For (8.43) wher e is the c onsist ency inde x, and is the p ower-la w inde x. Figur e 8.19: Variation of S hear S tress with S hear R ate According t o the H erschel-B ulkley Model (p.1116 ) shows ho w shear str ess ( ) varies with shear r ate ( ) for the H erschel-B ulkley mo del. Figur e 8.19: Variation of S hear S tress with S hear R ate According t o the H erschel-Bulk ley M odel If you cho ose the H erschel-B ulkley mo del f or B ingham plastics ,Equa tion 8.42 (p.1116 ) will b e used t o determine the fluid visc osity. The H erschel-B ulkley mo del is c ommonly used t o descr ibe ma terials such as c oncr ete, mud , dough, and t oothpast e, for which a c onstan t visc osity after a cr itical shear str ess is a r easonable assumption. In addition t o the tr ansition b ehavior b etween a flo w and no-flo w regime , the H erschel-B ulkley model c an also e xhibit a shear-thinning or shear-thick ening b ehavior dep ending on the v alue of . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1116Physical Properties8.4.5.5.1. Inputs for the H erschel-Bulk ley Mo del To use the H erschel-B ulkley mo del, cho ose herschel-bulk ley in the dr op-do wn list t o the r ight of Visc osit y.The Herschel-B ulkley Dialog Box (p.3411 ) will op en, and y ou c an cho ose b etween Shear Rate D ependen t and Shear R ate and Temp erature D ependen t. Enter the Consist enc y Inde x , Power-L aw Inde x ,Yield S tress Threshold ,Critical S hear R ate ,Referenc e Temp erature , and the r atio of the ac tivation ener gy to ther modynamic c onstan t ,Activation E nergy/R. 8.5. Thermal C onduc tivit y The ther mal c onduc tivit y must b e defined when hea t transf er is ac tive.You must define ther mal c on- duc tivit y when y ou ar e mo deling ener gy and visc ous flo w. ANSY S Fluen t provides se veral options f or definition of the ther mal c onduc tivit y: •constan t ther mal c onduc tivit y •temp erature- and/or c omp osition-dep enden t ther mal c onduc tivit y •kinetic theor y •anisotr opic (anisotr opic , biaxial, orthotr opic , cylindr ical or thotr opic , principal ax es and pr incipal v alues , user- defined anisotr opic) (f or solid ma terials only) •user-defined Each of these input options and the go verning ph ysical mo dels ar e detailed in this sec tion. User-defined func tions (UDFs) ar e descr ibed in the Fluen t Customiza tion M anual . In all c ases , you will define the Thermal C onduc tivit y in the Create/Edit M aterials D ialog Box (p.3386 ) (Figur e 8.20: The C reate/Edit M aterials D ialog Box (p.1118 )). Setup → Materials → Create/Edit... 1117Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Thermal C onduc tivit yFigur e 8.20: The C reate/Edit M aterials D ialo g Box Thermal c onduc tivit y is defined in units of W/m-K in SI units or B TU/hr-f t-°R in B ritish units . For additional inf ormation, see the f ollowing sec tions: 8.5.1. Constan t Thermal C onduc tivit y 8.5.2. Thermal C onduc tivit y as a F unction of Temp erature 8.5.3. Thermal C onduc tivit y Using K inetic Theor y 8.5.4. Comp osition-D ependen t Thermal C onduc tivit y for M ultic omp onen t Mixtures 8.5.5. Anisotr opic Thermal C onduc tivit y for Solids 8.5.1. Constan t Thermal C onduc tivit y If you w ant to define the ther mal c onduc tivit y as a c onstan t, check tha t constan t is selec ted in the drop-do wn list t o the r ight of Thermal C onduc tivit y in the Create/Edit M aterials D ialog Box (p.3386 ) (Figur e 8.20: The C reate/Edit M aterials D ialog Box (p.1118 )), and en ter the v alue of ther mal c onduc tivit y for the ma terial. For the default fluid (air), the ther mal c onduc tivit y is 0.0242 W/m-K. 8.5.2. Thermal C onduc tivit y as a F unc tion of Temp erature You c an also cho ose t o define the ther mal c onduc tivit y as a func tion of t emp erature.Three t ypes of func tions ar e available: •piec ewise-linear : (8.44) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1118Physical Properties•piec ewise-p olynomial: (8.45) •polynomial: (8.46) You c an input the da ta pairs ( ), ranges and c oefficien ts and , or c oefficien ts tha t descr ibe these func tions using the Create/Edit M aterials D ialog Box (p.3386 ), as descr ibed in Defining P roperties Using Temp erature-Dependen t Functions (p.1095 ). 8.5.3. Thermal C onduc tivit y Using K inetic Theor y If you ar e using the ideal gas la w (as descr ibed in Densit y (p.1099 )), you ha ve the option t o define the ther mal c onduc tivit y using k inetic theor y as (8.47) wher e is the univ ersal gas c onstan t, is the molecular w eigh t, is the ma terial’s sp ecified or comput ed visc osity, and is the ma terial’s sp ecified or c omput ed sp ecific hea t capacit y. To enable the use of this equa tion f or c alcula ting ther mal c onduc tivit y, selec t kinetic-theor y from the drop-do wn list t o the r ight of Thermal C onduc tivit y in the Create/Edit M aterials D ialog Box (p.3386 ). The solv er will use Equa tion 8.47 (p.1119 ) to comput e the ther mal c onduc tivit y. 8.5.4. Comp osition-D ependen t Thermal C onduc tivit y for M ultic omp onen t Mixtures If you ar e mo deling a flo w tha t includes mor e than one chemic al sp ecies (multic omp onen t flo w), you have the option t o define a c omp osition-dep enden t ther mal c onduc tivit y. (Note tha t you c an also define the ther mal c onduc tivit y of the mix ture as a c onstan t value or a func tion of t emp erature, or using k inetic theor y.) To define a c omp osition-dep enden t ther mal c onduc tivit y for a mix ture, follow these st eps: 1.For the mix ture ma terial, cho ose mass-w eigh ted-mixing-la w or, if you ar e using the ideal gas la w,ideal- gas-mixing-la w in the dr op-do wn list t o the r ight of Thermal C onduc tivit y. If you ha ve a user-defined func tion tha t you w ant to use t o mo del the ther mal c onduc tivit y, you c an cho ose either the user-defined metho d or the user-defined-mixing-la w metho d for the mix ture ma terial in the dr op-do wn list. The only diff erence between the user-defined-mixing-la w and the user-defined option f or sp e- cifying densit y, visc osity and ther mal c onduc tivit y of mix ture ma terials, is tha t with the user-defined- mixing-la w option, the individual pr operties of the sp ecies ma terials c an also b e sp ecified . Note that only the c onstan t, the p olynomial metho ds and the user-defined metho ds ar e available . Imp ortant If you use ideal-gas-mixing-la w for the ther mal c onduc tivit y of a mix ture, you must use ideal-gas-mixing-la w or mass-w eigh ted-mixing-la w for visc osity, because these two visc osity sp ecific ation metho ds ar e the only ones tha t allo w sp ecific ation of the 1119Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Thermal C onduc tivit ycomp onen t visc osities , which ar e used in the ideal gas la w for ther mal c onduc tivit y (Equa tion 8.48 (p.1120 )). 2.Click Change/C reate. 3.Define the ther mal c onduc tivit y for each of the fluid ma terials tha t mak e up the mix ture.You ma y define constan t or (if applic able) t emp erature-dep enden t ther mal c onduc tivities f or the individual sp ecies .You may also use k inetic theor y for the individual ther mal c onduc tivities , if applic able . 4.If you selec ted user-defined-mixing-la w, define the ther mal c onduc tivit y for each of the fluid ma terials that mak e up the mix ture.You ma y define c onstan t, or (if applic able) t emp erature-dep enden t ther mal conduc tivities , or user-defined ther mal c onduc tivities f or the individual sp ecies . More inf ormation ab out defining pr operties with user-defined func tions c an b e found in the Fluen t Customiza tion M anual . If you ar e using the ideal gas la w, the solv er will c omput e the mix ture ther mal c onduc tivit y based on kinetic theor y as (8.48) wher e (8.49) and is the mole fr action of sp ecies . For non-ideal gases , the mix ture ther mal c onduc tivit y is c omput ed based on a simple mass fr action average of the pur e sp ecies c onduc tivities: (8.50) 8.5.5. Anisotr opic Thermal C onduc tivit y for S olids The anisotr opic c onduc tivit y option in ANSY S Fluen t solv es the c onduc tion equa tion in solid z ones and shells with the ther mal c onduc tivit y sp ecified as a ma trix.The hea t flux v ector is wr itten as (8.51) The f ollowing options ar e available f or defining anisotr opic ther mal c onduc tivit y in ANSY S Fluen t. These ar e discussed b elow. •anisotr opic •biaxial (a vailable f or shells only) •orthotr opic •cylindr ical or thotr opic Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1120Physical Properties•principal ax es and pr incipal v alues •user-defined anisotr opic Note When p ostpr ocessing solid ma terial pr operties, the Thermal C onduc tivit y will b e displa yed as z ero if an anisotr opic ther mal c onduc tivit y mo del is b eing used f or a solid ma terial. Imp ortant The anisotr opic c onduc tivit y options ar e available only with the pr essur e-based solv er; you cannot use them with the densit y-based solv ers. 8.5.5.1. Anisotr opic Thermal C onduc tivit y For anisotr opic diffusion, the ther mal c onduc tivit y ma trix (Equa tion 8.51 (p.1120 )) is sp ecified as (8.52) wher e is the c onduc tivit y and is a ma trix (2 2 for two dimensions and 3 3 for thr ee-dimen- sional pr oblems). Note tha t can b e a non-symmetr ic ma trix. To define anisotr opic ther mal c onduc tivit y for a solid ma terial, selec t anisotr opic for Thermal C on- duc tivit y in the Create/Edit M aterials D ialog Box (p.3386 ) (Figur e 8.20: The C reate/Edit M aterials D ialog Box (p.1118 )). Note the f ollowing: •If the pr incipal ax es of y our anisotr opic ma terial ar e not aligned with the global c oordina te sy stem of y our simula tion, it ma y be easier f or y ou t o use one of the f ollowing options: if the ax es ar e or thogonal, you can use the orthotr opic option, as descr ibed in Orthotr opic Thermal C onduc tivit y (p.1123 ); if the ax es ar e not or thogonal, you c an use the principal-ax es-v alues option, as descr ibed in Principal A xes and P rincipal Values (p.1126 ). If you use the anisotr opic option with unaligned ax es, it is y our r esponsibilit y to transf orm the ther mal c onduc tivit y pr operties in to the tensor aligned with the global c oordina te sy stem. •The anisotr opic option is appr opriate when the c omp onen ts of the matrix ar e constan ts and do not vary indep enden tly; if this is not the c ase, you c an use a UDF t o define the ma trix and selec t user-defined- anisotr opic-k , as descr ibed in User-D efined A nisotr opic Thermal C onduc tivit y (p.1128 ). Selec ting anisotr opic will op en the Anisotr opic C onduc tivit y Dialog Box (p.3417 ) (Figur e 8.21: The A n- isotr opic C onduc tivit y Dialog Box (p.1122 )). 1121Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Thermal C onduc tivit yFigur e 8.21: The A nisotr opic C onduc tivit y D ialo g Box In the Anisotr opic C onduc tivit y Dialog Box (p.3417 ), enter the Matrix C omp onen ts of ma trix and then selec t the Conduc tivit y ( in Equa tion 8.52 (p.1121 )) to be a constan t, polynomial func tion of temp erature (polynomial ,piec ewise-linear ,piec ewise-p olynomial ), or user-defined func tion. See Constan t Thermal C onduc tivit y (p.1118 ) and Thermal C onduc tivit y as a F unction of Temp erature (p.1118 ) for details on c onstan ts and ther mal p olynomial func tions . When y ou selec t the user-defined option, the User-D efined F unctions D ialog Box (p.3406 ) will op en, allowing y ou t o ho ok a DEFINE_PROPERTY UDF only if y ou ha ve pr eviously loaded a c ompiled UDF library or in terpreted the UDF . Other wise , you will get an er ror message . Details ab out user-defined func tions c an b e found in the Fluen t Customiza tion M anual . 8.5.5.2. Biaxial Thermal C onduc tivit y Biaxial ther mal c onduc tivit y is applic able only f or solid ma terials used f or the w all shell c onduc tion model. To define a biaxial ther mal c onduc tivit y, selec t biaxial in the dr op-do wn list f or Thermal Conduc tivit y in the Create/Edit M aterials D ialog Box (p.3386 ).This op ens the Biaxial C onduc tivit y Dialog Box (p.3412 ) (Figur e 8.22: The B iaxial C onduc tivit y Dialog Box (p.1123 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1122Physical PropertiesFigur e 8.22: The Biaxial C onduc tivit y D ialo g Box In the Biaxial C onduc tivit y Dialog Box (p.3412 ), both the c onduc tivit y nor mal t o the sur face of the shell (Transv erse C onduc tivit y) and the c onduc tivit y par allel t o the sur face of the shell ( Planar C onduc t- ivity) can b e defined as constan t,polynomial ,piec ewise-linear , or piec ewise-p olynomial . See Constan t Thermal C onduc tivit y (p.1118 ) and Thermal C onduc tivit y as a F unction of Temp erature (p.1118 ) for details on these par amet ers. Note tha t the Planar C onduc tivit y is isotr opic . See Figur e 13.7: The Shell C onduc tion M anager D ialog Box (p.1484 ). 8.5.5.3. Orthotr opic Thermal C onduc tivit y When the or thotr opic ther mal c onduc tivit y is used , the ther mal c onduc tivities in the principal dir ections are sp ecified .The c onduc tivit y ma trix is then c omput ed as (8.53) To define an or thotr opic ther mal c onduc tivit y in solids , selec t orthotr opic in the dr op-do wn list f or Thermal C onduc tivit y in the Create/Edit M aterials D ialog Box (p.3386 ).This op ens the Orthotr opic Conduc tivit y Dialog Box (p.3415 ) (Figur e 8.23: The Or thotr opic C onduc tivit y Dialog Box (p.1124 )). 1123Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Thermal C onduc tivit yFigur e 8.23: The Or thotr opic C onduc tivit y D ialo g Box Since the dir ections are mutually or thogonal, only the first t wo need t o be sp ecified f or three-dimensional pr oblems . is defined using X,Y, Z under Direction 0 C omp onen ts, and is defined using X,Y, Z under Direction 1 C omp onen ts.You c an define Conduc tivit y 0 ,Conduc t- ivity 1 , and Conduc tivit y 2 as constan t,polynomial ,piec ewise-linear ,piec ewise-p oly- nomial func tions of t emp erature, or user-defined . See Constan t Thermal C onduc tivit y (p.1118 ) and Thermal C onduc tivit y as a F unction of Temp erature (p.1118 ) for details on c onstan t and t emp erature profile func tions . When y ou selec t the user-defined option, the User-D efined F unctions D ialog Box (p.3406 ) will op en, allowing y ou t o ho ok a DEFINE_PROPERTY UDF only if y ou ha ve pr eviously loaded a c ompiled UDF Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1124Physical Propertieslibrary or in terpreted the UDF . Other wise , you will get an er ror message . More inf ormation ab out user-defined func tions c an b e found in the Fluen t Customiza tion M anual . Imp ortant For two-dimensional pr oblems , only the func tions and the unit v ector need to be sp ecified . 8.5.5.4. Cylindric al O rthotr opic Thermal C onduc tivit y The or thotr opic c onduc tivit y of solids c an b e sp ecified in c ylindr ical coordina tes.To define the or tho- tropic ther mal c onduc tivit y in c ylindr ical coordina tes, selec t cyl-or thotr opic in the dr op-do wn list f or Thermal C onduc tivit y in the Create/Edit M aterials D ialog Box (p.3386 ).This op ens the Cylindr ical Or- thotr opic C onduc tivit y Dialog Box (p.3413 ) (Figur e 8.24: The C ylindr ical Or thotr opic C onduc tivit y Dialog Box (p.1125 )). Figur e 8.24: The C ylindr ical Or thotr opic C onduc tivit y D ialo g Box In thr ee-dimensional c ases , the or igin and the dir ection of the c ylindr ical coordina te sy stem must b e specified along with the r adial, tangen tial, and axial dir ection c onduc tivities . In t wo-dimensional c ases , 1125Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Thermal C onduc tivit ythe or igin of the c ylindr ical coordina te sy stem must b e sp ecified along with the r adial and tangen tial direction c onduc tivities . Note tha t in t wo-dimensional c ases , the dir ection is alw ays along the +Z axis . ANSY S Fluen t will aut oma tically c omput e the anisotr opic c onduc tivit y ma trix at each c ell fr om this input. The c alcula tion is based on the lo cation of the c ell in the c ylindr ical coordina te sy stem sp ecified . You c an define the Radial C onduc tivit y,Tangen tial C onduc tivit y, and Axial C onduc tivit y as con- stan t,polynomial ,piec ewise-linear ,piec ewise-p olynomial , or as user-defined func tions of t emp er- ature. See Constan t Thermal C onduc tivit y (p.1118 ) and Thermal C onduc tivit y as a F unction of Temp er- ature (p.1118 ) for details on c onstan t and ther mal pr ofile func tions . When y ou selec t the user-defined option, the User-D efined F unctions D ialog Box (p.3406 ) will op en, allowing y ou t o ho ok a DEFINE_PROPERTY UDF only if y ou ha ve pr eviously loaded a c ompiled UDF library or in terpreted the UDF . Other wise , you will get an er ror message . More inf ormation ab out user-defined func tions c an b e found in the Fluen t Customiza tion M anual . Imp ortant For c onduc tivit y calcula tions near the w all, the c ell ne xt to the w all is chosen f or c omputing the c onduc tivit y ma trix inst ead of the w all itself . 8.5.5.5. Principal A xes and P rincipal Values When the pr incipal ax es of y our anisotr opic ma terial ar e not aligned with the global c oordina te sy stem of the simula tion, you c an define the ther mal c onduc tivit y using the c omp onen ts of these ax es ( , , and f or 3D pr oblems , ) and the asso ciated pr inciple v alues ( , , and f or 3D pr oblems , ). The ax es tak e the f ollowing f orm: (8.54) Note tha t while the ax es must b e linear ly indep enden t vectors, the y do not ha ve to be unit v ectors or or thogonal. An example of pr incipal ax es tha t are not aligned with the global c oordina te sy stem is sho wn in Figur e 8.25: Unaligned P rincipal A xes (p.1127 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1126Physical PropertiesFigur e 8.25: Unaligned P rincipal A xes Represen ting the ther mal c onduc tivit y ma trix ( in Equa tion 8.51 (p.1120 )) in ma trix nota tion ( ), the f ollowing equa tion is used b y ANSY S Fluen t to transf orm the pr incipal ax es and pr incipal v alues into the c orrect tensor f orm: (8.55) The ma trices in the pr evious equa tion ar e defined as f ollows: (8.56) (8.57) wher e is the c onduc tivit y. To use pr incipal ax es and pr incipal v alues t o define the anisotr opic ther mal c onduc tivit y for y our solid ma terial, selec t principal-ax es-v alues for Thermal C onduc tivit y in the Create/Edit M aterials Dialog Box (p.3386 ) (Figur e 8.20: The C reate/Edit M aterials D ialog Box (p.1118 )).This will op en the Aniso- tropic C onduc tion - P rincipal C omp onen ts D ialog Box (p.3416 ) (Figur e 8.26: The A nisotr opic C onduc tivit y - Principal C omp onen ts D ialog Box (p.1128 )). 1127Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Thermal C onduc tivit yFigur e 8.26: The A nisotr opic C onduc tivit y - P rincipal C omp onen ts D ialo g Box In the Principal A xes group b ox of the Anisotr opic C onduc tion - P rincipal C omp onen ts D ialog Box (p.3416 ), enter the i,j, and k comp onen ts for each of the n1,n2, and n3 vectors ( Equa- tion 8.54 (p.1126 )) tha t define the pr incipal ax es of y our ma terial in the global c oordina te sy stem; not e that these must b e linear ly indep enden t vectors.Then in the Principal Values group b ox, enter the K1,K2, and K3 values tha t define the magnitudes of the pr incipal v alues along the asso ciated pr in- cipal ax es. Finally , mak e a selec tion fr om the Conduc tivit y drop-do wn menu t o sp ecify (in Equa- tion 8.57 (p.1127 )) as a constan t, polynomial func tion of t emp erature (polynomial ,piec ewise-linear , piec ewise-p olynomial ), or user-defined func tion, and then define it using the numb er-en try box that becomes a vailable or the dialo g box tha t op ens. See Constan t Thermal C onduc tivit y (p.1118 ) and Thermal C onduc tivit y as a F unction of Temp erature (p.1118 ) for details on c onstan ts and ther mal func tions . When y ou selec t the user-defined option, the User-D efined F unctions D ialog Box (p.3406 ) will op en, allowing y ou t o ho ok a DEFINE_PROPERTY UDF only if y ou ha ve pr eviously loaded a c ompiled UDF library or in terpreted the UDF . Other wise , you will get an er ror message . Details ab out user-defined func tions c an b e found in the Fluen t Customiza tion M anual . 8.5.5.6. User -Defined A nisotr opic Thermal C onduc tivit y You ha ve the option of mo deling anisotr opic c onduc tion f or domains wher e the c omp onen ts of the ther mal c onduc tivit y ma trix ( in Equa tion 8.52 (p.1121 )) are not c onstan ts and v ary indep enden tly, perhaps as a func tion of spac e or b ecause the domain has man y anisotr opic ma terials stit ched t ogether to form a c omp osite.To use this option, you must first define the c onduc tivit y ma trix using a UDF , as descr ibed in DEFINE_ANISOTROPIC_CONDUCTIVITY in the Fluen t Customiza tion M anual . After y ou ha ve in terpreted or c ompiled the DEFINE_ANISOTROPIC_CONDUCTIVITY UDF , you must then selec t user-defined-anisotr opic-k for Thermal C onduc tivit y in the Create/Edit M aterials Dialog Box (p.3386 ).This will op en the User-D efined F unctions D ialog Box (p.3406 ), which y ou c an use to ho ok the UDF . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1128Physical Properties8.6. User-D efined Sc alar (UDS) D iffusivit y There ar e two types of UDS diffusivit y tha t you c an sp ecify in ANSY S Fluen t: isotr opic and anisotr opic . Diffusion is isotr opic when it is the same in all dir ections . Isotr opic diffusion c oefficien ts can b e sp ecified in two ways: either as a single user-defined tha t applies t o all UDS tr ansp ort equa tions defined f or your mo del; or on a p er-sc alar basis as constan ts,polynomial func tions of t emp erature, or user-defined func tions . Diffusion is anisotr opic when the diffusion c oefficien ts ar e diff erent in diff erent dir ections . Anisotr opic diffusion c an b e sp ecified b y a t ensor diffusion c oefficien t ma trix (Equa tion 8.58 (p.1129 )) for each UDS (in b oth fluid and solid z ones) in f our diff erent ways: gener al anisotr opic ,orthotr opic ,cyl-or thotr opic , and user-defined-anisotr opic . All UDS diffusivit y par amet ers ar e set fr om the Create/Edit M aterials Dialog Box (p.3386 ) and ar e discussed b elow. Note tha t details ab out ho w to define and use UDFs in UDS tr ansp ort equa tions is discussed in the Fluen t Customiza tion M anual . The sec ond-or der diffusion t erm in the most gener al form is (8.58) wher e is a 3 3 tensor in 3D . For additional inf ormation, see the f ollowing sec tions: 8.6.1. Isotr opic D iffusion 8.6.2. Anisotr opic D iffusion 8.6.3. User-D efined A nisotr opic D iffusivit y 8.6.1. Isotr opic D iffusion For isotr opic diffusion, in Equa tion 8.58 (p.1129 ) is equal t o a sc alar times the iden tity ma trix and the equa tion r educ es to (8.59) You c an sp ecify isotr opic diffusivit y as a single user-defined func tion tha t applies t o all UDS tr ansp ort equa tions . For this c ase, cho ose user-defined from the dr op-do wn list f or UDS D iffusivit y in the Create/Edit M aterials D ialog Box (p.3386 ). Setup → Materials If you ha ve pr eviously loaded a c ompiled UDF libr ary or ha ve in terpreted the UDF , then the User- Defined F unctions D ialog Box (p.3406 ) will op en, allo wing y ou t o ho ok the DEFINE_DIFFUSIVITY UDF t o ANSY S Fluen t. If no func tions ha ve been loaded , you will get an er ror message . More inf ormation about user-defined func tions c an b e found in the Fluen t Customiza tion M anual . Isotr opic diffusion c oefficien ts can also b e defined on a p er-sc alar basis b y selec ting defined-p er-uds from the dr op-do wn list f or UDS D iffusivit y in the Create/Edit M aterials D ialog Box (p.3386 ).This will open the UDS D iffusion C oefficien ts D ialog Box (p.3433 ) (Figur e 8.27: The UDS D iffusion C oefficien ts Dialog Box (p.1130 )). 1129Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User-D efined Sc alar (UDS) D iffusivit yFigur e 8.27: The UDS D iffusion C oefficien ts D ialo g Box In the UDS D iffusion C oefficien ts D ialog Box (p.3433 ), selec t a sc alar equa tion (f or e xample ,uds-0 ) and then cho ose a constan t,polynomial , or user-defined func tion fr om the Coefficien t drop-do wn list. For the default fluid (air), the c onstan t diffusion c oefficien t is kg/m-s . If you cho ose polynomial , the Polynomial P rofile D ialog Box (p.3402 ) will op en and y ou c an sp ecify y our c oefficien ts as a func tion of temp erature. See Inputs f or P olynomial F unctions (p.1095 ) for details . When y ou selec t the user-defined option, the User-D efined F unctions D ialog Box (p.3406 ) will op en, allowing y ou t o ho ok a DEFINE_DIFFUSIVITY UDF only if y ou ha ve pr eviously loaded a c ompiled UDF libr ary or in terpreted a UDF . Other wise , you will get an er ror message . More inf ormation ab out user-defined func tions c an b e found in the Fluen t Customiza tion M anual . 8.6.2. Anisotr opic D iffusion You c an sp ecify anisotr opic diffusion c oefficien ts in b oth fluid and solid z ones b y defining the t ensor diffusion c oefficien t ma trix (Equa tion 8.58 (p.1129 )) on a p er-sc alar basis .You c an use anisotr opic diffusivit y for UDS sc alar tr ansp ort equa tions t o mo del sp ecies tr ansp ort equa tions in p orous media and in solids wher e sp ecies diffusion sho ws anisotr opic b ehavior. Imp ortant •Note tha t the anisotr opic diffusion options discussed in the f ollowing sec tions ar e available with the pr essur e-based solv er and the densit y-based solv ers. •UDS diffusion c oefficien ts can b e postpr ocessed only in those c ells tha t ha ve isotr opic diffusivit y. In all other c ells, the diffusion c oefficien t will b e zero. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1130Physical PropertiesIn all c ases , you enable anisotr opic diffusion b y selec ting defined-p er-uds under UDS D iffusivit y in the Create/Edit M aterials D ialog Box (p.3386 ).This will op en the UDS D iffusion C oefficien ts D ialog Box (p.3433 ) (Figur e 8.27: The UDS D iffusion C oefficien ts D ialog Box (p.1130 )). Setup → Materials In the UDS D iffusion C oefficien ts D ialog Box (p.3433 ), selec t a sc alar equa tion (f or e xample ,uds-0 ) and then cho ose one of the f ollowing metho ds under Coefficien t to sp ecify the anisotr opic diffusion coefficien t.These metho ds ar e descr ibed in detail b elow. •anisotr opic •orthotr opic •cylindr ical or thotr opic •user-defined anisotr opic 8.6.2.1. Anisotr opic D iffusivit y For anisotr opic diffusivit y, you c an sp ecify in Equa tion 8.58 (p.1129 ) in the f orm wher e is a constan t ma trix in 3D and is a sc alar multiplier . The diffusion c oefficien t ma trix is sp ecified as (8.60) wher e is the diffusivit y and is a ma trix (2 2 for two dimensions and 3 3 for thr ee-dimensional problems). Note tha t can b e a non-symmetr ic ma trix. To sp ecify anisotr opic diffusion c oefficien ts, first selec t a sc alar equa tion (f or e xample ,uds-0 ) from the User-D efined Sc alar D iffusion list in the UDS D iffusion C oefficien ts D ialog Box (p.3433 ) (Fig- ure 8.27: The UDS D iffusion C oefficien ts D ialog Box (p.1130 )).Then cho ose anisotr opic in the dr op- down list under Coefficien t.This will op en the Anisotr opic UDS D iffusivit y dialo g box (Figur e 8.28: The Anisotr opic UDS D iffusivit y Dialog Box (p.1132 )). 1131Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User-D efined Sc alar (UDS) D iffusivit yFigur e 8.28: The A nisotr opic UDS D iffusivit y D ialo g Box In the Anisotr opic UDS D iffusivit y dialo g box, enter the Matrix C omp onen ts and then selec t the Diffusivit y to be a constan t, polynomial func tion of t emp erature (polynomial ,piec ewise-linear , piec ewise-p olynomial ), or user-defined . See Inputs f or P olynomial F unctions (p.1095 ),Inputs f or Piecewise-Linear F unctions (p.1096 ), and Inputs f or P iecewise-P olynomial F unctions (p.1098 ) for details on p olynomial t emp erature func tions . When y ou selec t the user-defined option, the User-D efined F unctions D ialog Box (p.3406 ) will op en, allowing y ou t o ho ok a DEFINE_DIFFUSIVITY UDF only if y ou ha ve pr eviously loaded a c ompiled UDF libr ary or in terpreted a UDF . Other wise , you will get an er ror message . More inf ormation ab out user-defined func tions c an b e found in the Fluen t Customiza tion M anual . 8.6.2.2. Orthotr opic D iffusivit y For or thotr opic diffusivit y, you c an sp ecify in Equa tion 8.58 (p.1129 ) through ’pr incipal ’ direction vectors and diffusion c oefficien ts along these dir ections . ANSY S Fluen t, in tur n, comput es from paramet ers tha t you supply .The pr incipal dir ections ar e the same e verywher e, but each of he dir ec- tional diffusion c oefficien ts can b e sp ecified as a c onstan t, polynomial func tion of t emp erature, or through user-defined func tions . When or thotr opic diffusivit y is used , the diffusion c oefficien ts in the pr incipal dir ections are sp ecified .The diffusivit y ma trix is then c omput ed as (8.61) Imp ortant For two-dimensional pr oblems , only the func tions and the unit v ector need to be sp ecified . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1132Physical PropertiesTo sp ecify or thotr opic diffusion c oefficien ts, first selec t a sc alar equa tion (f or e xample ,uds-0 ) from the User-D efined Sc alar D iffusion list in the UDS D iffusion C oefficien ts D ialog Box (p.3433 ) (Fig- ure 8.27: The UDS D iffusion C oefficien ts D ialog Box (p.1130 )).Then cho ose orthotr opic in the dr op- down list under Coefficien t.This will op en the Orthotr opic UDS D iffusivit y dialo g box (Fig- ure 8.29: The Or thotr opic UDS D iffusivit y Dialog Box (p.1133 )). Figur e 8.29: The Or thotr opic UDS D iffusivit y D ialo g Box Since the dir ections are mutually or thogonal, only the first t wo need t o be sp ecified f or three-dimensional pr oblems . is defined using X,Y,Z under Direction 0 C omp onen ts, and is defined using X,Y,Z under Direction 1 C omp onen ts.You c an define Diffusivit y 0 ,Diffusivit y 1 , and Diffusivit y 2 as constan t,polynomial ,piec ewise-linear ,piec ewise-p olynomial func tions of t emp erature, or user-defined . See Inputs f or P olynomial F unctions (p.1095 ),Inputs f or Piecewise-Linear F unctions (p.1096 ), and Inputs f or P iecewise-P olynomial F unctions (p.1098 ) for details on p olynomial t emp erature func tions . When y ou selec t the user-defined option, the User-D efined F unctions D ialog Box (p.3406 ) will op en, allowing y ou t o ho ok a DEFINE_DIFFUSIVITY UDF only if y ou ha ve pr eviously loaded a c ompiled UDF libr ary or in terpreted a UDF . If no func tions ha ve been loaded , you will get an er ror message . More inf ormation ab out user-defined func tions c an b e found in the Fluen t Customiza tion M anual . 1133Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User-D efined Sc alar (UDS) D iffusivit y8.6.2.3. Cylindric al O rthotr opic D iffusivit y Orthotr opic UDS diffusivit y can also b e sp ecified on a p er-sc alar basis in c ylindr ical coordina tes.This metho d is similar t o or thotr opic UDS diffusivit y, except tha t the pr incipal dir ections ar e sp ecified as radial, tangen tial, and axial. To sp ecify c ylindr ical or thotr opic diffusion c oefficien ts, first selec t a sc alar equa tion (f or e xample ,uds- 0) from the User-D efined Sc alar D iffusion list in the UDS D iffusion C oefficien ts D ialog Box (p.3433 ) (Figur e 8.27: The UDS D iffusion C oefficien ts D ialog Box (p.1130 )).Then cho ose cyl-or thotr opic in the drop-do wn list under Coefficien t.This will op en the Cylindr ical Or thotr opic UDS D iffusivit y dialo g box (Figur e 8.30: The C ylindr ical Or thotr opic UDS D iffusivit y Dialog Box (p.1134 )). Figur e 8.30: The C ylindr ical Or thotr opic UDS D iffusivit y D ialo g Box In thr ee-dimensional c ases , the or igin and the dir ection of the c ylindr ical coordina te sy stem must b e specified along with the r adial, tangen tial, and axial dir ection c onduc tivities . In t wo-dimensional c ases , the or igin of the c ylindr ical coordina te sy stem must b e sp ecified along with the r adial and tangen tial direction c onduc tivities . Note tha t in t wo-dimensional c ases , the dir ection is alw ays along the +z axis . ANSY S Fluen t will aut oma tically c omput e the anisotr opic diffusivit y ma trix at each c ell fr om this input. The c alcula tion is based on the lo cation of the c ell in the c ylindr ical coordina te sy stem sp ecified . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1134Physical PropertiesYou c an define the Radial D iffusivit y,Tangen tial D iffusivit y, and Axial D iffusivit y as constan t, polynomial ,piec ewise-linear ,piec ewise-p olynomial , or as user-defined func tions of t emp erature, using the dr op-do wn list b elow each of the diffusivities . See Inputs f or P olynomial F unctions (p.1095 ), Inputs f or P iecewise-Linear F unctions (p.1096 ), and Inputs f or P iecewise-P olynomial F unctions (p.1098 ) for details on p olynomial t emp erature func tions . When y ou selec t the user-defined option, the User-D efined F unctions D ialog Box (p.3406 ) will op en, allowing y ou t o ho ok a DEFINE_DIFFUSIVITY UDF only if y ou ha ve pr eviously loaded a c ompiled UDF libr ary or in terpreted a UDF . If no func tions ha ve been loaded , you will get an er ror message . More inf ormation ab out user-defined func tions c an b e found in the Fluen t Customiza tion M anual . 8.6.3. User-D efined A nisotr opic D iffusivit y You c an sp ecify in Equa tion 8.58 (p.1129 ) on a p er-sc alar basis , directly, through user-defined func tions (UDFs). To sp ecify a UDF f or anisotr opic diffusivit y on a p er-sc alar basis , first selec t a sc alar equa tion (f or e xample , uds-0 ) from the User-D efined Sc alar D iffusion list in the UDS D iffusion C oefficien ts D ialog Box (p.3433 ) (Figur e 8.31: The UDS D iffusion C oefficien ts D ialog Box (p.1135 )). Figur e 8.31: The UDS D iffusion C oefficien ts D ialo g Box Then cho ose user-defined-anisotr opic in the dr op-do wn list under Coefficien t.The User-D efined Functions D ialog Box (p.3406 ) will op en, allo wing y ou t o ho ok a DEFINE_ANISOTROPIC_DIFFUSIVITY UDF only if y ou ha ve pr eviously loaded a c ompiled UDF libr ary or in terpreted a UDF . Other wise , you will get an er ror message . More inf ormation ab out user-defined func tions c an b e found in the Fluen t Customiza tion M anual . 1135Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User-D efined Sc alar (UDS) D iffusivit y8.7. Specific H eat Capacit y The sp ecific hea t capacit y must b e defined when the ener gy equa tion is ac tive. ANSY S Fluen t provides several options f or definition of the hea t capacit y: •constan t hea t capacit y •temp erature- and/or c omp osition-dep enden t hea t capacit y •kinetic theor y Each of these input options and the go verning ph ysical mo dels ar e detailed in this sec tion. In all c ases , you will define the Cp in the Create/Edit M aterials D ialog Box (p.3386 ). Setup → Materials Specific hea t capacit y is input in units of J/k g-K in SI units or B TU/lbm-°R in B ritish units . Imp ortant For c ombustion applic ations , a temp erature-dep enden t sp ecific hea t is r ecommended . For additional inf ormation, see the f ollowing sec tions: 8.7.1. Input of C onstan t Specific H eat Capacit y 8.7.2. Specific H eat Capacit y as a F unction of Temp erature 8.7.3. Defining S pecific H eat Capacit y Using K inetic Theor y 8.7.4. Specific H eat Capacit y as a F unction of C omp osition 8.7.1. Input of C onstan t Specific H eat Capacit y If you w ant to define the hea t capacit y as a c onstan t, check tha t constan t is selec ted in the dr op-do wn list t o the r ight of Cp in the Create/Edit M aterials D ialog Box (p.3386 ), and en ter the v alue of hea t capacit y. The sp ecific hea t for the default fluid (air) is 1006.43 J/k g-K. 8.7.2. Specific H eat Capacit y as a F unc tion of Temp erature You c an also cho ose t o define the sp ecific hea t capacit y as a func tion of t emp erature.Three t ypes of func tions ar e available: •piec ewise-linear : (8.62) •piec ewise-p olynomial: (8.63) •polynomial: (8.64) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1136Physical PropertiesYou c an input the da ta pairs ( ), ranges and c oefficien ts and , or c oefficien ts tha t descr ibe these func tions using the Create/Edit M aterials D ialog Box (p.3386 ), as descr ibed in Defining P roperties Using Temp erature-Dependen t Functions (p.1095 ). 8.7.3. Defining S pecific H eat Capacit y Using K inetic Theor y If you ar e using the ideal gas la w (as descr ibed in Densit y (p.1099 )), you ha ve the option t o define the specific hea t capacit y using k inetic theor y as (8.65) wher e is the numb er of mo des of ener gy storage (degr ees of fr eedom) f or the gas sp ecies tha t you c an input b y selec ting kinetic-theor y from the dr op-do wn list t o the r ight of Cp in the Create/Edit Materials D ialog Box (p.3386 ).The solv er will use y our k inetic theor y inputs in Equa tion 8.65 (p.1137 ) to comput e the sp ecific hea t capacit y. See Kinetic Theor y Paramet ers (p.1151 ) for details ab out k inetic theor y inputs . 8.7.4. Specific H eat Capacit y as a F unc tion of C omp osition If you ar e mo deling a flo w tha t includes mor e than one chemic al sp ecies (multic omp onen t flo w), you have the option t o define a c omp osition-dep enden t sp ecific hea t capacit y.You c an also define the heat capacit y of the mix ture as a c onstan t value or a func tion of t emp erature, or using k inetic theor y. To define a c omp osition-dep enden t sp ecific hea t capacit y for a mix ture, follow these st eps: 1.For the mix ture ma terial, cho ose mixing-la w in the dr op-do wn list t o the r ight of Cp. 2.Click Change/C reate. 3.Define the sp ecific hea t capacit y for each of the fluid ma terials tha t mak e up the mix ture.You ma y define constan t or (if applic able) t emp erature-dep enden t hea t capacities f or the individual sp ecies .You ma y also use k inetic theor y for the individual hea t capacities , if applic able . The solv er will c omput e the mix ture’s sp ecific hea t capacit y as a mass fr action a verage of the pur e species hea t capacities: (8.66) 8.8. Radia tion P roperties When y ou ha ve ac tivated one of the r adia tion mo dels (e xcept f or the sur face-to-sur face mo del, which requir es no additional pr operties), ther e will b e additional pr operties f or y ou t o set in the Create/Edit Materials D ialog Box (p.3386 ): •For the P-1 mo del, you must set the r adia tion Absor ption C oefficien t and Scattering C oefficien t ( and in Equa tion 5.18 in the Theor y Guide ). •For the R osseland mo del, set the Absor ption C oefficien t and Scattering C oefficien t ( and in Equa- tion 5.19 in the Theor y Guide ). •For the DTRM, only the Absor ption C oefficien t is requir ed ( in Equa tion 5.52 in the Theor y Guide ). 1137Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Radia tion P roperties•For the DO mo del, set the Absor ption C oefficien t and the Scattering C oefficien t ( and in Equa tion 5.59 in the Theor y Guide ). In addition, if you ar e mo deling semi-tr anspar ent media, specify the Refr active Inde x ( or in Equa tion 5.78 in the Theor y Guide ).With the DO mo del, you c an sp ecify r adia tion pr operties f or solid ma terials, to be used when semi-tr anspar ent media ar e mo deled . •For the MC mo del, set the Absor ption C oefficien t and the Scattering C oefficien t ( and in Equa tion 5.59 in the Theor y Guide ). In addition, if you ar e mo deling semi-tr anspar ent media, specify the Refr active Inde x ( or in Equa tion 5.78 in the Theor y Guide ).With the MC mo del, you c an sp ecify r adia tion pr operties f or solid ma terials, to be used when semi-tr anspar ent media ar e mo deled . For additional inf ormation, see the f ollowing sec tions: 8.8.1. Absor ption C oefficien t 8.8.2. Scattering C oefficien t 8.8.3. Refractive Inde x 8.8.4. Reporting the R adia tion P roperties 8.8.1. Absor ption C oefficien t To define the absor ption c oefficien t, you c an sp ecify a c onstan t value , a temp erature-dep enden t func tion (see Defining P roperties U sing Temp erature-Dependen t Functions (p.1095 )), a comp osition- dep enden t func tion, or a user-defined func tion. The absorbing and emitting par ts of the r adia tive transf er equa tion (R TE), Equa tion 5.17 in the Theor y Guide , is a func tion of the absor ption c oefficien t. The absorbing or emitting eff ects dep end on the chosen r adia tion mo del. If ther e ar e only absor ption effects, then Lamb ert’s La w of absor ption applies (8.67) wher e is the r adia tion in tensit y, is the absor ption c oefficien t, and is the distanc e thr ough the material. If you ar e mo deling non-gr ay radia tion with the P-1, DO , or MC r adia tion mo dels , you also ha ve the option t o sp ecify a c onstan t absor ption c oefficien t in each of the gr ay bands .The absor ption c oefficien t is request ed in units of 1/length. Along with the sc attering c oefficien t, it descr ibes the change in r adi- ation in tensit y per unit length along the pa th thr ough the fluid medium. Absor ption c oefficien ts can be comput ed using tables of emissivit y for and O, which ar e gener ally a vailable in t extbooks on r adia tion hea t transf er. 8.8.1.1. Inputs for a C onstant A bsorption C oefficient To define a c onstan t absor ption c oefficien t, simply en ter the v alue in the field ne xt to Absor ption Coefficien t in the Create/Edit M aterials D ialog Box (p.3386 ). Selec t constan t in the dr op-do wn list first if it is not alr eady selec ted. 8.8.1.2. Inputs for a C omp osition-D ependent A bsorption C oefficient ANSY S Fluen t also allo ws you t o input a c omp osition-dep enden t absor ption c oefficien t, wher e the local value of is a func tion of the lo cal mass fr actions of w ater v apor and c arbon dio xide .This modeling option c an b e useful f or the simula tion of r adia tion in c ombustion applic ations .The v ariable- absor ption-c oefficien t mo del used b y ANSY S Fluen t is the w eigh ted-sum-of-gr ay-gases mo del ( WSGGM) descr ibed in Radia tion in C ombusting F lows in the Theor y Guide .To ac tivate it, first enable the sp ecies calcula tion and mak e sur e tha t and O ar e pr esen t in the mix ture. Next, selec t wsggm-domain- based ,wsggm-user-sp ecified , or user-defined-w sggm in the dr op-do wn list t o the r ight of Absor p- Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1138Physical Propertiestion C oefficien t in the Create/Edit M aterials dialo g box. If you selec t user-defined-w sggm , the User-D efined F unc tions dialo g box will op en, allo wing y ou t o selec t a pr eviously loaded c ompiled UDF libr ary or a pr eviously in terpreted UDF (see Hooking DEFINE_WSGGM_ABS_COEFF UDFs in the Fluen t Customiza tion M anual ).The WSGGM options diff er in the metho d used t o comput e the pa th length, as descr ibed in the sec tion tha t follows. 8.8.1.2.1. Path L ength Inputs When the WSGGM is used t o comput e the absor ption c oefficien t, you c an cho ose ho w pa th length, , is defined f or Equa tion 5.106 in the Theor y Guide . See Radia tion in C ombusting F lows in the Theor y Guide to det ermine which metho d is appr opriate for y our c ase. You will selec t the pa th length metho d when y ou cho ose the pr operty input metho d for Absor ption Coefficien t, as descr ibed pr eviously . •If you cho ose wsggm-domain-based , is set equal t o a mean b eam length c alcula ted b y ANSY S Fluen t according t o Equa tion 5.107 in the Theor y Guide , which is an a verage dimension of the domain; no fur ther inputs ar e requir ed. •If you cho ose wsggm-user-sp ecified , is set equal t o a mean b eam length tha t you en ter for Path Length in the WSGGM U ser S pecified D ialog Box (p.3434 ). •If you cho ose user-defined-w sggm , ANSY S Fluen t will initially c omput e the absor ption c oefficien t in the same manner as descr ibed f or the wsggm-domain-based option; however, you ha ve the option of writing a user-defined func tion tha t cust omiz es this c alcula ted v alue . If the so ot mo del is enabled , you can also use the UDF t o cust omiz e the so ot absor ption c oefficien t comput ed b y ANSY S Fluen t. See DEFINE_WSGGM_ABS_COEFF in the Fluen t Customiza tion M anual for fur ther details . 8.8.1.2.1.1. Inputs for a N on-Gr ay Radiation A bsorption C oefficient If you ar e using the non-gr ay DO mo del (see The DO M odel E qua tions of the Theor y Guide and De- fining N on-G ray Radia tion f or the DO M odel (p.1510 )), the non-gr ay P-1 mo del (see The P-1 M odel Equa tions of the Theor y Guide and Setting U p the P-1 M odel with N on-G ray Radia tion (p.1491 )), or the non-gr ay MC mo del (see Monte Carlo (MC) R adia tion M odel Theor y), you c an sp ecify a diff erent constan t absor ption c oefficien t for each of the bands used b y the gr ay-band mo del. Selec t gray- band from the Absor ption C oefficien t drop-do wn list in the Create/Edit M aterials dialo g box and then define the absor ption c oefficien t for each band in the Gray-Band A bsor ption C oefficien t Dialog Box (p.3435 ). (Note tha t you must c omplet e this dialo g box in or der t o pr oceed.) 8.8.1.2.1.2. Effec t of P articles and S oot on the A bsorption C oefficient ANSY S Fluen t will include the eff ect of par ticles on the absor ption c oefficien t if y ou ha ve tur ned on the Particle R adia tion In teraction option in the Discrete Phase M odel D ialog Box (p.3360 ) (only f or the P-1 and DO r adia tion mo dels). If you ar e mo deling so ot formation and y ou w ant to include the eff ect of so ot formation on the absor ption c oefficien t, turn on the Soot-R adia tion In teraction in the Soot M odel D ialog Box (p.3343 ). The so ot eff ects can b e included f or an y of the r adia tion mo dels , as long as y ou ar e using the WSGGM to comput e a c omp osition-dep enden t absor ption c oefficien t. Note tha t you c an use the user-defined- wsggm option t o cust omiz e the so ot absor ption c oefficien t calcula ted b y ANSY S Fluen t, as descr ibed previously . 1139Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Radia tion P roperties8.8.2. Scattering C oefficien t The sc attering c oefficien t is, by default , set t o zero, and it is assumed t o be isotr opic .You c an sp ecify a constan t value , a temp erature-dep enden t func tion (see Defining P roperties U sing Temp erature-De- penden t Functions (p.1095 )), or a user-defined func tion. You c an also sp ecify a non-isotr opic phase func tion. The sc attering c oefficien t is r equest ed in units of 1/length. Along with the absor ption c oefficien t, it descr ibes the change in r adia tion in tensit y per unit length along the pa th thr ough the fluid medium. You ma y want to incr ease the sc attering c oefficien t in c ombustion sy stems , wher e par ticula tes ma y be pr esen t. 8.8.2.1. Inputs for a C onstant Sc attering C oefficient To define a c onstan t scattering c oefficien t, simply en ter the v alue in the field ne xt to Scattering Coefficien t in the Create/Edit M aterials D ialog Box (p.3386 ). (Selec t constan t in the dr op-do wn list first if it is not alr eady selec ted.) 8.8.2.2. Inputs for the Sc attering P hase F unc tion Scattering is assumed t o be isotr opic , by default , but y ou c an also sp ecify a linear-anisotr opic sc attering func tion. If you ar e using the DO mo del, Delta-E ddingt on and user-defined sc attering func tions ar e also a vailable . 8.8.2.2.1. Isotr opic P hase F unc tion To mo del isotr opic sc attering, selec t isotr opic in the Scattering P hase F unc tion drop-do wn list. No fur ther inputs ar e nec essar y.This is the default setting in ANSY S Fluen t. 8.8.2.2.2. Linear -Anisotr opic P hase F unc tion To mo del anisotr opic sc attering, selec t linear-anisotr opic in the Scattering P hase F unc tion drop- down list and set the v alue of the phase func tion c oefficien t ( in Equa tion 5.19 in the Theor y Guide ). 8.8.2.2.3. Delta-E ddingt on P hase F unc tion To use a D elta-E ddingt on phase func tion, selec t delta-eddingt on in the Scattering P hase F unc tion drop-do wn list. This will op en the Delta-E ddingt on Sc attering F unction D ialog Box (p.3435 ), in which you c an sp ecify the Forward Sc attering F actor and Asymmetr y Factor ( and in Equa tion 5.68 in the Theor y Guide ). Since this is a mo dal dialo g box, you must t end t o it immedia tely. 8.8.2.2.4. User -Defined P hase F unc tion To use a user-defined phase func tion, selec t user-defined in the Scattering P hase F unc tion drop- down list. The user-defined func tion will c ontain sp ecific ations f or and in Equa tion 5.69 in the Theor y Guide . More inf ormation ab out user-defined func tions c an b e found in the Fluen t Customiz- ation M anual . 8.8.3. Refr active Inde x The r efractive inde x is the r atio of sp eed of ligh t in the medium t o the sp eed of ligh t in v acuum. It is by default set t o 1. You c an sp ecify a c onstan t value in the field ne xt to Refr active Inde x. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1140Physical PropertiesIf you ar e using the non-gr ay DO mo del (see The DO M odel E qua tions of the Theor y Guide and Defining Non-G ray Radia tion f or the DO M odel (p.1510 )), the non-gr ay P-1 mo del (see The P-1 M odel E qua tions of the Theor y Guide and Setting U p the P-1 M odel with N on-G ray Radia tion (p.1491 )), or the non-gr ay MC mo del (see Monte Carlo (MC) R adia tion M odel Theor y), you c an sp ecify a diff erent constan t refractive inde x for each of the bands used b y the gr ay-band mo del. Selec t refractive-band from the Refr active Inde x drop-do wn list in the Create/Edit M aterials dialo g box and then define the r efractive inde x for each band in the Gray-Band R efractive Inde x Dialog Box (p.3436 ). Note tha t because this is a mo dal dialo g box, you must t end t o it immedia tely. 8.8.4. Rep orting the R adia tion P roperties You c an displa y the c omput ed lo cal values f or and using the Absor ption C oefficien t and Scat- tering C oefficien t items in the Radia tion... categor y of the v ariable selec tion dr op-do wn list tha t ap- pears in p ostpr ocessing dialo g boxes.You will also find the Refr active Inde x in the Radia tion... cat- egor y. 8.9. Mass D iffusion C oefficien ts For sp ecies tr ansp ort calcula tions , ther e ar e two ways to mo del the diffusion of chemic al sp ecies . For most applic ations the F ick’s law appr oxima tion is adequa te, but f or some applic ations (f or e xample , diffusion-domina ted laminar flo ws such as chemic al vapor dep osition), the full multic omp onen t diffusion model is r ecommended . Imp ortant The full multic omp onen t diffusion mo del is enabled in the Species M odel D ialog Box (p.3294 ) and is c omputa tionally e xpensiv e. For additional inf ormation, see the f ollowing sec tions: 8.9.1. Fickian D iffusion 8.9.2. Full M ultic omp onen t Diffusion 8.9.3. Anisotr opic S pecies D iffusion 8.9.4. Thermal D iffusion C oefficien ts 8.9.5. Mass D iffusion C oefficien t Inputs 8.9.6. Mass D iffusion C oefficien t Inputs f or Turbulen t Flow 8.9.1. Fickian D iffusion Mass diffusion c oefficien ts ar e requir ed whene ver y ou ar e solving sp ecies tr ansp ort equa tions in mul- ticomp onen t flo ws. Mass diffusion c oefficien ts ar e used t o comput e the diffusion flux of a chemic al species in a laminar flo w using (b y default) F ick’s law: (8.68) wher e is the mass diffusion c oefficien t for sp ecies in the mix ture and is the ther mal (S oret) diffusion c oefficien t. Equa tion 8.68 (p.1141 ) is str ictly v alid when the mix ture comp osition is not changing , or when is indep enden t of c omp osition. This is an acc eptable appr oxima tion in dilut e mix tures when , for all except the c arrier gas . ANSY S Fluen t can also c omput e the tr ansp ort of non-dilut e mix tures in 1141Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Mass D iffusion C oefficien tslaminar flo ws by treating such mix tures as multic omp onen t systems .Within ANSY S Fluen t, can be sp ecified in a v ariety of w ays, including b y sp ecifying , the binar y mass diffusion c oefficien t of comp onen t in c omp onen t . is not used dir ectly, however; inst ead, the diffusion c oefficien t in the mix ture, , is c omput ed as (8.69) wher e is the mole fr action of sp ecies .You c an input or for each chemic al sp ecies , as de- scribed in Mass D iffusion C oefficien t Inputs (p.1146 ). In turbulen t flo ws,Equa tion 8.68 (p.1141 ) is replac ed with the f ollowing f orm: (8.70) wher e is the eff ective Schmidt numb er for the turbulen t flo w: (8.71) and is the eff ective mass diffusion c oefficien t due t o turbulenc e. In turbulen t flo ws your mass diffusion c oefficien t inputs c onsist of defining the molecular c ontribution to diffusion using the same metho ds a vailable f or the laminar c ase, with the added option t o alt er the default settings f or the turbulen t Schmidt numb er. As seen fr om Equa tion 8.71 (p.1142 ), this par a- met er relates the eff ective mass diffusion c oefficien t due t o turbulenc e with the edd y visc osity . As discussed in Mass D iffusion C oefficien t Inputs f or Turbulen t Flow (p.1150 ), the turbulen t diffusion c oef- ficien t nor mally o verwhelms the laminar diffusion c oefficien t, so the default c onstan t value f or the laminar diffusion c oefficien t is usually acc eptable . 8.9.2. Full M ultic omp onen t Diffusion A careful tr eatmen t of chemic al sp ecies diffusion in the sp ecies tr ansp ort and ener gy equa tions is im- portant when details of the molecular tr ansp ort processes ar e signific ant (for e xample , in diffusion- domina ted laminar flo ws). As one of the laminar-flo w diffusion mo dels , ANSY S Fluen t has the abilit y to mo del full multic omp onen t sp ecies tr ansp ort. 8.9.2.1. Gener al Theor y For multic omp onen t systems it is not p ossible , in gener al, to der ive relations f or the diffusion flux es containing the gr adien t of only one c omp onen t (as descr ibed in Fickian D iffusion (p.1141 )). Here, the Maxwell-S tefan equa tions will b e used t o obtain the diffusiv e mass flux. This will lead t o the definition of gener alized F ick’s law diffusion c oefficien ts [133] (p.4012 ).This metho d is pr eferred o ver computing the multic omp onen t diffusion c oefficien ts sinc e their e valua tion r equir es the c omputa tion of co- factor det erminan ts of siz e , and one det erminan t of siz e [128] (p.4012 ), wher e is the numb er of chemic al sp ecies . 8.9.2.2. Maxwell-St efan E quations From M erk [79] (p.4009 ), the M axwell-S tefan equa tions c an b e wr itten as Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1142Physical Properties(8.72) wher e, = the mole fr action = the diffusion v elocity = the binar y mass diffusion c oefficien t of sp ecies in sp ecies = the ther mal diffusion c oefficien t. For an ideal gas the M axwell diffusion c oefficien ts ar e equal t o the binar y diffusion c oefficien ts. If the external f orce is assumed t o be the same on all sp ecies and tha t pressur e diffusion is negligible , then . Since the diffusiv e mass flux v ector is , the ab ove equa tion c an b e wr itten as (8.73) After some ma thema tical manipula tions , the diffusiv e mass flux v ector, , can b e obtained fr om (8.74) wher e is the mass fr action of sp ecies . Other t erms ar e defined as f ollows: (8.75) wher e, and = ma trices = an ma trix of the gener alized F ick’s law diffusion c oefficien ts [133] (p.4012 ) = the molecular w eigh t = a subscr ipt used t o define a mean molecular w eigh t in the mix ture 1143Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Mass D iffusion C oefficien ts8.9.3. Anisotr opic S pecies D iffusion You c an mo del anisotr opic sp ecies diffusion in p orous media. For F ickian diffusion, the mass flux v ector of sp ecies is mo deled as , (8.76) wher e is the p orosity, is the anisotr opic diffusion ma trix in the p orous z one , and the r emaining nomencla ture is the same as in Equa tion 8.70 (p.1142 ). The F ull M ulti-c omp onen t (M axwell-S tefan) anisotr opic diffusion flux v ector is c alcula ted similar t o Equa tion 8.74 (p.1143 ) as, (8.77) To acc oun t for anisotr opic sp ecies diffusion in p orous media simula tions , selec t the Anisotr opic S pecies Diffusion check b ox in the Porous Z one tab of the Fluid dialo g box and sp ecify the Matrix C omp on- ents for the anisotr opic diffusion ma trix (see Figur e 8.32: Anisotr opic S pecies D iffusion M atrix (p.1144 )). Figur e 8.32: Anisotr opic S pecies D iffusion M atrix By default , is the iden tity ma trix tha t corresponds t o isotr opic diffusion. 8.9.4. Thermal D iffusion C oefficien ts The ther mal diffusion c oefficien ts can b e defined as c onstan ts, polynomial func tions , user-defined func tions , or using the f ollowing empir ically-based c omp osition-dep enden t expression der ived fr om [62] (p.4008 ): Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1144Physical Properties(8.78) This f orm of the S oret diffusion c oefficien t will c ause hea vy molecules t o diffuse less r apidly , and ligh t molecules t o diffuse mor e rapidly , towards hea ted sur faces. 8.9.4.1. Thermal D iffusion C oefficient Inputs If you ha ve enabled ther mal diffusion (in the Species M odel D ialog Box (p.3294 )), you c an define the ther mal diffusion c oefficien ts in the Create/Edit M aterials D ialog Box (p.3386 ) as f ollows: 1.Selec t one of the f ollowing thr ee metho ds in the dr op-do wn list t o the r ight of Thermal D iffusion Coefficien t: •Choose kinetic-theor y to ha ve ANSY S Fluen t comput e the ther mal diffusion c oefficien ts using the empir ically-based e xpression in Equa tion 8.78 (p.1145 ). No fur ther inputs ar e requir ed f or this option. •Choose specified to input the c oefficien t for each sp ecies .The Thermal D iffusion C oefficien ts D ialog Box (p.3432 ) (Figur e 8.33: The Thermal D iffusion C oefficien ts D ialog Box (p.1145 )) will op en. Further inputs are descr ibed in the st ep 2. •Choose user-defined to use a user-defined func tion. More inf ormation ab out user-defined func tions can b e found in the Fluen t Customiza tion M anual . 2.(specified metho d only) F or each sp ecies in the Species Thermal D i list of the Thermal D iffusion Coefficien ts dialo g box, perform the f ollowing st eps: Figur e 8.33: The Thermal D iffusion C oefficien ts D ialo g Box 1145Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Mass D iffusion C oefficien tsa.Selec t the sp ecies in the Species Thermal D i list f or which y ou ar e going t o define the ther mal diffusion coefficien t. b.Define for the selec ted sp ecies either as a c onstan t value or as a p olynomial func tion of t emp er- ature: •To define a c onstan t diffusion c oefficien t, selec t constan t (the default) in the dr op-do wn list b elow Coefficien t, and then en ter the v alue in the field b elow the list. •To define a t emp erature-dep enden t diffusion c oefficien t, cho ose polynomial in the Coefficien t drop-do wn list and then define the p olynomial c oefficien ts as descr ibed in Defining P roperties Using Temp erature-Dependen t Functions (p.1095 ). 8.9.5. Mass D iffusion C oefficien t Inputs By default , the solv er comput es the sp ecies diffusion using Equa tion 8.68 (p.1141 ) (for laminar flo ws) with y our inputs f or , the diffusion c oefficien t for sp ecies in the mix ture. For turbulen t flo ws, species diffusion is c omput ed with Equa tion 8.70 (p.1142 ). You c an input the mass diffusion c oefficien ts using one of the f ollowing metho ds: •Constan t dilut e appr oxima tion (F ickian diffusion only): define one c onstan t for all . •Dilute appr oxima tion (F ickian diffusion only): define each as a c onstan t or as a p olynomial func tion of temp erature (if hea t transf er is enabled). •Multic omp onen t metho d: define the binar y diffusion of sp ecies in each sp ecies , as a c onstan t or a polynomial func tion of t emp erature, or (f or ideal gases only) using k inetic theor y. •Unity Lewis N umb er: define under the assumption of unit y Lewis numb er for all sp ecies in the mix ture. •User-defined func tion (UDF): define a single func tion tha t will apply t o all mass diffusion c oefficien ts.This is done using the DEFINE_DIFFUSIVITY macr o and is e xplained in the Fluen t Customiza tion M anual . You should cho ose t o input (using one of the first t wo metho ds) if y ou ar e mo deling a dilut e mixture, with chemic al sp ecies pr esen t at low mass fr action in a “carrier” fluid tha t is pr esen t at high concentration. You ma y want to define the individual binar y mass diffusion c oefficien ts, , if y ou ar e modeling a non-dilut e mix ture. If you cho ose t o define , the solv er will c omput e the diffusion of species in the mix ture using Equa tion 8.69 (p.1142 ), unless y ou ha ve enabled full multic omp onen t diffusion. The L ewis numb er is the r atio of ther mal diffusivit y (Prandtl numb er) t o mass diffusivit y (Schmidt numb er). Flames with non-unit y Lewis numb er can displa y instabilities , as w ell as non-adiaba tic flame temp eratures.The U nity Lewis N umb er mass diffusivit y option a voids these issues , and is par ticular ly appr opriate for the Thick ened F lame mo del. Imp ortant If you w ant to use the full multic omp onen t diffusion mo del descr ibed in Full M ultic omp onen t Diffusion (p.1142 ), turn on the Full M ultic omp onen t Diffusion option in the Species M odel Dialog Box (p.3294 ), and then selec t the multic omp onen t diffusion mo del. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1146Physical PropertiesYou will define or for each chemic al sp ecies using the Create/Edit M aterials D ialog Box (p.3386 ). Setup → Materials The diffusion c oefficien ts ha ve units of /s in SI units or /s in B ritish units . 8.9.5.1. Constant D ilut e Appr oximation Inputs To use the c onstan t dilut e appr oxima tion metho d, follow these st eps: 1.Selec t constan t-dilut e-appx in the dr op-do wn list t o the r ight of Mass D iffusivit y. 2.Enter a single v alue of .The same v alue will b e used f or the diffusion c oefficien t of each sp ecies in the mix ture. 8.9.5.2. Dilut e Appr oximation Inputs To use the dilut e appr oxima tion metho d, follow the st eps b elow: 1.Selec t dilut e-appr ox in the dr op-do wn list t o the r ight of Mass D iffusivit y. 2.In the r esulting Mass D iffusion C oefficien ts D ialog Box (p.3431 ) (Figur e 8.34: The M ass D iffusion C oefficien ts Dialog Box for D ilute Approxima tion (p.1147 )), selec t the sp ecies in the Species D i list f or which y ou ar e going t o define the mass diffusion c oefficien t. Figur e 8.34: The M ass D iffusion C oefficien ts D ialo g Box for D ilute Appr oxima tion 3.You c an define for the selec ted sp ecies either as a c onstan t value or (if hea t transf er is ac tive) as a polynomial func tion of t emp erature: 1147Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Mass D iffusion C oefficien ts•To define a c onstan t diffusion c oefficien t, selec t constan t (the default) in the dr op-do wn list b elow Coefficien t, and then en ter the v alue in the field b elow the list. •To define a t emp erature-dep enden t diffusion c oefficien t, cho ose polynomial in the Coefficien t drop- down list and then define the p olynomial c oefficien ts as descr ibed in Inputs f or P olynomial F unc- tions (p.1095 ). (8.79) 4.Repeat steps 2 and 3 un til you ha ve defined diffusion c oefficien ts for all sp ecies in the Species D i list in the Mass D iffusion C oefficien ts D ialog Box (p.3431 ). 8.9.5.3. Multic omp onent Metho d Inputs To use the multic omp onen t metho d, and define c onstan t or t emp erature-dep enden t diffusion c oeffi- cien ts, follow the st eps b elow: 1.Selec t multic omp onen t in the dr op-do wn list t o the r ight of Mass D iffusivit y. 2.In the r esulting Mass D iffusion C oefficien ts D ialog Box (p.3431 ) (Figur e 8.35: The M ass D iffusion C oefficien ts Dialog Box for the M ultic omp onen t Metho d (p.1148 )), selec t the sp ecies in the Species D i list and the Species Dj list f or which y ou ar e going t o define the mass diffusion c oefficien t for sp ecies in sp ecies . Figur e 8.35: The M ass D iffusion C oefficien ts D ialo g Box for the M ultic omp onen t Metho d 3.You c an define for the selec ted pair of sp ecies as a c onstan t value or as a p olynomial func tion of temp erature (if hea t transf er is ac tive). •To define a c onstan t diffusion c oefficien t, selec t constan t (the default) in the dr op-do wn list b elow Coefficien t, and then en ter the v alue in the field b elow the list. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1148Physical Properties•To define a t emp erature-dep enden t diffusion c oefficien t, cho ose polynomial in the Coefficien t drop- down list and then define the p olynomial c oefficien ts as descr ibed in Inputs f or P olynomial F unc- tions (p.1095 ). (8.80) 4.Repeat steps 2 and 3 un til you ha ve defined diffusion c oefficien ts for all pairs of sp ecies in the Species Di and Species Dj lists in the Mass D iffusion C oefficien ts D ialog Box (p.3431 ). To use the multic omp onen t metho d, and define the diffusion c oefficien t using k inetic theor y (available only when the ideal gas la w is used), follow these st eps: 1.Choose kinetic-theor y in the dr op-do wn list t o the r ight of Mass D iffusivit y. 2.Click Change/C reate after completing other pr operty definitions f or the mix ture ma terial. 3.Define the L ennar d-Jones par amet ers, and , for each sp ecies (fluid ma terial), as descr ibed in Kinetic Theor y Paramet ers (p.1151 ). The solv er will use a mo dific ation of the C hapman-Ensk og formula [75] (p.4009 ) to comput e the diffusion coefficien t using k inetic theor y: (8.81) wher e, is the absolut e pr essur e is the diffusion c ollision in tegral, which is a measur e of the in teraction of the molecules in the sy stem is a func tion of the quan tity , wher e (8.82) is the B oltzmann c onstan t, which is defined as the gas c onstan t, , divided b y Avogadr o’s numb er. for the mix ture is the geometr ic average: (8.83) For a binar y mix ture, is c alcula ted as the arithmetic average of the individual s: (8.84) 8.9.5.4. Unit y Lewis Numb er The laminar mass diffusivit y of all sp ecies is c alcula ted as: 1149Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Mass D iffusion C oefficien tswher e denot es the mass diffusivit y of sp ecies in the mix ture, is the ther mal c onduc tivit y, is the mix ture densit y, and is the mix ture sp ecific hea t. 8.9.6. Mass D iffusion C oefficien t Inputs f or Turbulen t Flow When y our flo w is turbulen t, you will define or , as descr ibed f or laminar flo ws in Mass D iffusion Coefficien t Inputs (p.1146 ), and y ou will also ha ve the option t o alt er the default setting f or the turbulen t Schmidt numb er, , as defined in Equa tion 8.71 (p.1142 ). Usually , in a turbulen t flo w, the mass diffusion is domina ted b y the turbulen t transp ort as det ermined by the turbulen t Schmidt numb er (Equa tion 8.71 (p.1142 )).The turbulen t Schmidt numb er measur es the r elative diffusion of momen tum and mass due t o turbulenc e and is on the or der of unit y in all turbulen t flo ws. Because the turbulen t Schmidt numb er is an empir ical constan t tha t is r elatively in- sensitiv e to the molecular fluid pr operties, you will ha ve little r eason t o alt er the default v alue (0.7) for an y sp ecies . Should y ou w ant to mo dify the Schmidt numb er, enter a new v alue f or Turb . Schmidt N umb er in the Viscous M odel D ialog Box (p.3253 ). Setup → Models → Visc ous Edit... Imp ortant Note tha t the full multic omp onen t diffusion mo del descr ibed in Full M ultic omp onen t Diffu- sion (p.1142 ) is not r ecommended f or turbulen t flo ws. 8.10. Standar d State Enthalpies When y ou ar e solving a r eacting flo w using the finit e-rate or edd y dissipa tion mo del, you must define the standar d sta te en thalp y (also k nown as the f ormation en thalp y or hea t of f ormation), for each species .These inputs ar e used t o define the mix ture en thalp y as (8.85) wher e is the molecular w eigh t of the th species with units of k g/kmol and is the r eference temp erature at which is defined . Standar d sta te en thalpies ar e input in units of J/k g mol in SI units or in units of Btu/ mol in B ritish units . For each sp ecies in volved in the r eaction (tha t is, each fluid ma terial c ontained in the mix ture ma terial), you c an set the Standar d State Enthalp y and Referenc e Temp erature in the Create/Edit M aterials Dialog Box (p.3386 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1150Physical Properties8.11. Standar d State Entropies If you ar e using the finit e-rate mo del with r eversible r eactions (see Direct Use of F inite-Rate Kinetics (no TCI) in the Theor y Guide ), you must define the standar d sta te en tropy, for each sp ecies .These inputs ar e used t o define the mix ture en tropy as (8.86) wher e is the molecular w eigh t of the th species with units of k g/kmol and is the r eference temp erature at which is defined . Standar d sta te en tropies ar e input in units of J/k mol-K in SI units or in units of Btu/ mol-°R in B ritish units . For each sp ecies in volved in the r eaction (tha t is, each fluid ma terial c ontained in the mix ture ma terial), you c an set the Standar d State Entropy and Referenc e Temp erature in the Create/Edit M aterials Dialog Box (p.3386 ). 8.12. Unbur nt Thermal D iffusivit y If you ar e mo deling pr emix ed c ombustion (see Modeling P remix ed C ombustion (p.1749 )), the fluid ma- terial in y our domain should b e assigned the pr operties of the unbur nt mix ture, including the ther mal diffusivit y ( in Equa tion 9.8 in the Theor y Guide ). is defined as , and v alues a t standar d con- ditions c an b e found in c ombustion handb ooks (f or e xample ,[62] (p.4008 )).To det ermine v alues a t non- standar d conditions , you must use a thir d-par ty 1D c ombustion pr ogram with detailed chemistr y.You can set the Unbur nt Thermal D iffusivit y in the Create/Edit M aterials D ialog Box (p.3386 ). 8.13. Kinetic Theor y Paramet ers You ma y cho ose t o define the f ollowing pr operties using k inetic theor y when the ideal gas la w is enabled: •viscosity (for fluids) •ther mal c onduc tivit y (for fluids) •specific hea t capacit y (for fluids) •mass diffusion c oefficien ts (for multi-sp ecies mix tures) If you ar e using k inetic theor y for a fluid ’s visc osity (Equa tion 8.27 (p.1111 )), you must input the k inetic theor y par amet ers and for tha t fluid .These par amet ers ar e the L ennar d-Jones par amet ers and are referred t o by ANSY S Fluen t as the “char acteristic length ” and the “ener gy par amet er” respectively. •When k inetic theor y is applied t o calcula tion of a fluid ’s ther mal c onduc tivit y only , no inputs ar e requir ed. •To calcula te sp ecific hea t of a fluid using k inetic theor y (Equa tion 8.65 (p.1137 )), you need t o en ter the degr ees of fr eedom f or the fluid ma terial. •If you use k inetic theor y to define a mix ture ma terial’s mass diffusivit y (Equa tion 8.81 (p.1149 )), you must input and for each chemic al sp ecies . 1151Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Kinetic Theor y Paramet ersFor additional inf ormation, see the f ollowing sec tion: 8.13.1. Inputs f or K inetic Theor y 8.13.1. Inputs f or K inetic Theor y The pr ocedur e for using k inetic theor y is as f ollows: 1.Selec t kinetic-theor y as the pr operty sp ecific ation metho d for the Visc osit y,Thermal C onduc tivit y, or heat capacit y Cp of a fluid ma terial, or f or the Mass D iffusivit y of a mix ture ma terial. 2.If the ma terial for which y ou ha ve selec ted the k inetic theor y metho d for one or mor e pr operties is a fluid material, you must set the k inetic theor y par amet ers f or each of the c onstituen t species (fluid ma terials). The par amet ers t o be set ar e as f ollows: •L-J C haracteristic L ength •L-J E nergy Paramet er •Degrees of F reedom (only r equir ed if k inetic theor y is used f or sp ecific hea t) See the b eginning of this sec tion t o find out which par amet ers ar e requir ed t o calcula te each property using k inetic theor y. Characteristic length is defined in units of A ngstr oms .The ener gy par amet er is defined in units of ab- solut e temp erature. Degrees of fr eedom is a dimensionless input. All kinetic theor y ma terials c an b e found in the lit erature (for e xample ,[49] (p.4007 )). 8.14. Op erating P ressur e Specific ation of the op erating pr essur e aff ects your c alcula tion in diff erent ways for diff erent flo w regimes . This sec tion pr esen ts inf ormation ab out the op erating pr essur e, its r elevance for diff erent cases , and how to set it c orrectly. For additional inf ormation, see the f ollowing sec tions: 8.14.1. The S ignific ance of Op erating P ressur e 8.14.2. Operating P ressur e, Gauge P ressur e, and A bsolut e Pressur e 8.14.3. Setting the Op erating P ressur e 8.14.1. The S ignific anc e of Op erating P ressur e Operating pr essur e is signific ant for inc ompr essible ideal gas flo ws because it dir ectly det ermines the densit y: the inc ompr essible ideal gas la w comput es densit y as .You must ther efore be sur e to set the op erating pr essur e appr opriately. In lo w-M ach-numb er compr essible flo w, the o verall pr essur e dr op is small c ompar ed t o the absolut e static pr essur e, and c an b e signific antly aff ected b y numer ical roundoff .To understand wh y this is tr ue, consider a c ompr essible flo w with .The pr essur e changes , , are related t o the d ynamic head , , wher e is the sta tic pr essur e and is the r atio of sp ecific hea ts.This giv es the simple r elation- ship , so tha t as .Therefore, unless adequa te pr ecaution is tak en, low- Mach-numb er flo w calcula tions ar e very susc eptible t o roundoff er ror. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1152Physical PropertiesOperating pr essur e is signific ant for lo w-M ach-numb er compr essible flo ws because of its r ole in avoiding r oundoff er ror pr oblems . Ensur e tha t you set the op erating pr essur e appr opriately.You ma y want to sp ecify a floa ting op erating pr essur e inst ead of a c onstan t op erating pr essur e for lo w-M ach- numb er, time-dep enden t compr essible flo ws with a verage pr essur e in the domain v arying in time . See Floating Op erating P ressur e (p.1221 ) for details . Operating pr essur e is less signific ant for higher-M ach-numb er compr essible flo ws.The pr essur e changes in such flo ws are much lar ger than those in lo w-M ach-numb er compr essible flo ws, so ther e is no r eal problem with r oundoff er ror and , ther efore, no r eal need t o use gauge pr essur e. In fac t, it is c ommon convention t o use absolut e pr essur es in such c alcula tions . Since ANSY S Fluen t alw ays uses gauge pressur e, you c an simply set the op erating pr essur e to zero, mak ing gauge and absolut e pr essur es equiv alen t. If the densit y is assumed c onstan t or if it is der ived fr om a pr ofile func tion of t emp erature, the op erating pressur e is not used in the densit y calcula tion. Note tha t the default op erating pr essur e is 101325 P a. 8.14.2. Op erating P ressur e, Gauge P ressur e, and A bsolut e Pressur e ANSY S Fluen t avoids the pr oblem of r oundoff er ror (discussed in The S ignific ance of Op erating P res- sure (p.1152 )) by subtr acting the op erating pr essur e (gener ally a lar ge pr essur e roughly equal t o the average absolut e pr essur e in the flo w) fr om the absolut e pr essur e, and using the r esult (t ermed the gauge pr essur e).The r elationship b etween the op erating pr essur e, gauge pr essur e, and absolut e pressur e is sho wn b elow.The absolut e pr essur e is simply the sum of the op erating pr essur e and the gauge pr essur e: (8.87) All pr essur es tha t you sp ecify and all pr essur es c omput ed or r eported b y ANSY S Fluen t are gauge pressur es. 8.14.3. Setting the Op erating P ressur e The cr iteria for cho osing a suitable op erating pr essur e ar e based on the M ach-numb er regime of the flow and the r elationship tha t is used t o det ermine densit y. For e xample , if y ou use the ideal gas la w in an inc ompr essible flo w calcula tion (f or e xample , for a na tural convection pr oblem), you should use a value r epresen tative of the mean flo w pr essur e. To plac e this discussion in p ersp ective,Table 8.1: Recommended S ettings f or Op erating P ressur e (p.1153 ) shows the r ecommended appr oach f or setting op erating pr essur es.The default op erating pr essur e is 101325 P a. Table 8.1: Rec ommended S ettings f or Op erating P ressur e Operating P ressur e Mach N umb er Regime Densit y Rela tionship 0 or mean flo w pr essur e ideal gas la w mean flo w pr essur e ideal gas la w not used incompr essible profile func tion of t emp erature not used incompr essible constan t mean flo w pr essur e incompr essible incompr essible ideal gas la w 1153Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Operating P ressur eYou will set the Operating P ressur e in the Operating C onditions D ialog Box (p.3470 ). Setup → Cell Z one C onditions → Operating C onditions ... 8.15. Ref erenc e Pressur e Location For inc ompr essible flo ws tha t do not in volve an y pr essur e boundar ies, ANSY S Fluen t adjusts the gauge pressur e field af ter each it eration t o keep it fr om floa ting .This is done using the pr essur e in the c ell located a t (or near est t o) the r eference pr essur e lo cation. The pr essur e value in this c ell is subtr acted from the en tire gauge pr essur e field; as a r esult , the gauge pr essur e at the r eference pr essur e lo cation is alw ays zero. If pressur e boundar ies ar e involved, the adjustmen t is not needed and the r eference pressur e lo cation is ignor ed. The r eference pr essur e lo cation is , by default , the c ell c enter a t or closest t o (0,0,0). There ma y be cases in which y ou migh t want to mo ve the r eference pr essur e lo cation, perhaps lo cating it a t a p oint wher e the absolut e sta tic pr essur e is k nown (f or e xample , if y ou ar e planning t o compar e your r esults with experimen tal da ta).To change the lo cation, enter new ( X,Y,Z) coordina tes for Referenc e Pressur e Location in the Operating C onditions D ialog Box (p.3470 ). Setup → Cell Z one C onditions → Operating C onditions ... For additional inf ormation, see the f ollowing sec tion: 8.15.1. Actual R eference Pressur e Location 8.15.1. Actual Ref erenc e Pressur e Location For c ases tha t do not ha ve pr essur e-related b oundar y conditions (f or e xample , pressur e inlet , pressur e outlet , pressur e far-field , and so on), you need t o sp ecify the Referenc e Pressur e Location at a p oint in the pr oblem domain. Internally , ANSY S Fluen t sets the lo cation of the r eference pr essur e at a sligh tly different nearb y location. Therefore, the ac tual lo cation used as the pr essur e reference is diff erent than that of y our input v alue .To report the ac tual r eference pr essur e lo cation tha t ANSY S Fluen t uses , use the f ollowing t ext command: define → operating-conditions → used-ref-pressure-location Imp ortant •This t ext command is a vailable only when the c ase is initializ ed and has no pr essur e-related boundar y zones . •Reporting the ac tual r eference pr essur e location is not a vailable thr ough the gr aphic al user in- terface. 8.16. Real G as M odels Some engineer ing pr oblems in volve fluids tha t do not b ehave as ideal gases . For e xample , at very high- pressur e or v ery low-temp erature conditions (f or e xample , the flo w of a r efriger ant thr ough a c ompr essor) the flo w cannot t ypic ally b e mo deled accur ately using the ideal-gas assumption. Therefore, the r eal gas Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1154Physical Propertiesmodel allo ws you t o solv e accur ately f or the fluid flo w and hea t transf er pr oblems wher e the w orking fluid b ehavior de viates fr om the ideal-gas assumption. ANSY S Fluen t provides thr ee r eal gas options f or solving these t ypes of flo ws: •Cubic E qua tion of S tate Models (p.1157 ) •The NIST R eal G as M odels (p.1173 ) •The U ser-D efined R eal G as M odel (p.1185 ) All the mo dels allo w you t o solv e for either a single-sp ecies fluid flo w or a multiple-sp ecies mix ture fluid flo w. For additional inf ormation, see the f ollowing sec tions: 8.16.1. Introduction 8.16.2. Choosing a R eal G as M odel 8.16.3. Cubic E qua tion of S tate Models 8.16.4. The NIST R eal G as M odels 8.16.5. The U ser-D efined R eal G as M odel 8.16.1. Introduc tion The sta tes a t which a pur e ma terial c an e xist c an b e gr aphic ally r epresen ted in diagr ams of pr essur e vs. temp erature (PT diagr ams) and pr essur e vs. molecular or sp ecific v olume (PV diagr ams). Homo gen- eous fluids ar e nor mally divided in to two classes , liquids and gases . However the distinc tion c annot always be shar ply dr awn, because the t wo phases b ecome indistinguishable a t wha t is c alled the cr it- ical p oint. A typic al pr essur e-temp erature (PT ) diagr am of a pur e ma terial is sho wn in Figur e 8.36: Typ- ical PT D iagr am of a P ure M aterial (p.1155 ). Figur e 8.36: Typic al PT D iagr am of a P ure M aterial This figur e sho ws the single phase r egions , as w ell as the c onditions of P and T wher e two phases coexist. Therefore the solid and the gas r egion ar e divided b y the sublima tion cur ve, the liquid and gas r egions b y the v aporization cur ve, and the solid and liquid r egions b y the fusion cur ve.The thr ee curves meet a t the tr iple p oint, wher e all thr ee phases c oexist in equilibr ium. Although the fusion 1155Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Real G as M odelscurve continues up ward indefinit ely, the v aporization cur ve termina tes a t the cr itical p oint.The c oordin- ates of this p oint are called the cr itical pr essur e and cr itical temp erature .These r epresen t the highest t emp erature and pr essur e at which a pur e ma terial c an e xist in v apor-liquid equilibr ium. At temp eratures and pr essur es ab ove the cr itical p oint, the ph ysical pr operty diff erences tha t diff erentiate the liquid phase fr om the gas phase b ecome less defined .This r eflec ts the fac t tha t, at extremely high temp eratures and pr essur es, the liquid and gaseous phases b ecome indistinguishable .This new phase , which has some pr operties tha t are similar t o a liquid and some pr operties tha t are similar t o a gas , is called a sup ercritical fluid . Figur e 8.37: Typic al PV D iagr am of a P ure M aterial Figur e 8.37: Typic al PV D iagr am of a P ure M aterial (p.1156 ) presen ts a t ypic al diagr am of pr essur e versus molar or sp ecific v olume (PV diagr am) of a pur e ma terial.The dome shap ed cur ve ACD is c alled the saturation dome and separ ates the single phase r egions in the diagr am; cur ve AC represen ts the sa t- urated liquid and cur ve CD the sa turated v apor.The ar ea under the sa turation dome A CD is the t wo- phase r egion and r epresen ts all p ossible mix tures of v apor and liquid in equilibr ium. Curve ECB is the critical isother m and e xhibits a hor izontal inflec tion a t point C a t the t op of the dome .This is the cr it- ical p oint.The sp ecific v olume c orresponding t o the cr itical p oint, is c alled the cr itical sp ecific v olume .The c onditions t o the r ight of the cr itical isother m ECB c orrespond t o sup ercritical fluid .The dashed lines CF and C G in Figur e 8.37: Typic al PV D iagr am of a P ure M aterial (p.1156 ) represen t the liquid and the v apor spino dal cur ves with the r egions A CF and DC G between the sa turation and spino dal lines represen ting the sup erheated liquid and sup ercooled v apor sta tes, respectively.These sta tes ar e called "metastable" b ecause the y exist t emp orarily in small lo cal regions un til phase change o ccurs . As an example , liquid metastable sta tes ma y be formed in situa tions of fast depr essur ization, dep ending on the r ate of depr essur ization and the disturbanc es tha t tend t o mak e the liquid flash in to vapor. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1156Physical Properties8.16.2. Choosing a Real G as M odel The equa tion of sta te is the ma thema tical expression tha t relates pr essur e, molar or sp ecific v olume , and t emp erature for an y pur e homo geneous fluid in equilibr ium sta tes. The simplest equa tion of sta te is the ideal gas la w, which is appr oxima tely v alid f or the lo w pr essur e gas r egion of the PT and PV diagr ams . Ideal gas b ehavior c an b e expected when or and If your flo w conditions c orrespond t o either of those c ases , you ma y use the ideal gas la w in y our simula tion. Another idealiza tion, tha t of the inc ompr essible fluid , can b e emplo yed f or the lo w pr essur e region of the liquid phase . A c onstan t densit y option is the appr opriate selec tion in tha t case. However, both of these appr oaches ar e not go od appr oxima tions f or flo w conditions close t o and beyond the cr itical p oint, wher e the fluid b ehavior c annot b e descr ibed b y the ideal gas , or the inc om- pressible liquid assumptions .We refer to a fluid under those c onditions as a r eal fluid , or a r eal gas and mor e comple x relations ar e used f or the det ermina tion of its ph ysical and ther modynamic pr op- erties. ANSY S Fluen t provides the f ollowing options f or solving r eal fluid pr oblems: •The cubic equa tion of sta te mo dels c an b e used t o solv e pr oblems in the gas , liquid , and sup ercritical fluid regimes .The mo dels ar e not a vailable f or the t wo-phase r egion under the phase dome . For fur ther details see Cubic E qua tion of S tate Models (p.1157 ). •The NIST r eal gas mo del c an b e used t o solv e pr oblems in the liquid , or gas and sup ercritical fluid r egimes . The mo del do es not allo w mo deling of the t wo-phase r egion. For fur ther details see The NIST R eal G as Models (p.1173 ). •The user-defined r eal gas mo del allo ws you t o solv e pr oblems in all r egimes , as long as appr opriate rela- tionships ar e pr ovided thr ough the user-defined r eal gas func tions . For fur ther details see The U ser-D efined Real G as M odel (p.1185 ). The c oncepts pr esen ted in this sec tion f or pur e ma terials ar e also e xtended t o multic omp onen t mix tures with the in troduc tion of appr opriate comp osition-dep enden t par amet ers in the r eal gas equa tions of state and the ma terial pr operty mo dels . All the r eal-gas mo deling options ab ove allo w for either single- species or multic omp onen t flo w mo deling . In addition, you ma y solv e reacting flo w pr oblems with the cubic equa tions of sta te mo dels and the user-defined r eal gas func tions . 8.16.3. Cubic E qua tion of S tate M odels 8.16.3.1. Overview and Limitations An equa tion of sta te is a ther modynamic equa tion, which pr ovides a ma thema tical relationship between t wo or mor e sta te func tions asso ciated with the ma tter, such as its t emp erature, pressur e, volume , or in ternal ener gy. One of the simplest equa tions of sta te for this pur pose is the ideal gas 1157Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Real G as M odelslaw, which is r oughly accur ate for gases a t low pr essur es and high t emp eratures. However, this equa tion b ecomes incr easingly inaccur ate at higher pr essur es and lo wer temp eratures, and fails t o predic t condensa tion fr om a gas t o a liquid . Introduced in 1949, the R edlich-K wong equa tion of sta te [95] (p.4010 ) was a c onsider able impr ovemen t over other equa tions of tha t time . It is an analytic cubic equa tion of sta te and is still of in terest primar ily due t o its r elatively simple f orm.The or iginal f orm is (8.88) wher e P = absolut e pr essur e (P a) R = univ ersal gas c onstan t V = sp ecific molar v olume ( ) T = t emp erature (K) = reduc ed t emp erature , wher e is the cr itical temp erature and are constan ts related dir ectly t o the fluid cr itical pr essur e and t emp erature Many investiga tors ha ve attempt ed t o impr ove the accur acy of the R edlich-K wong equa tion. ANSY S Fluen t has adopt ed the or iginal f orm of the R edlich-K wong equa tion, as w ell as the f ollowing mo dified forms: •The S oave-Redlich-K wong [124] (p.4011 ) equa tion is a thr ee-par amet er equa tion of sta te, which c an b e applied f or v apor, sup ercritical, and liquid pr operty pr edic tions . It has f ound wide acc eptanc e mainly in the oil and gas industr y and r equir es k nowledge of the cr itical temp erature, critical pr essur e, and ac entric factor. It was de velop ed b y replacing the R edlich-K wong a ttractive coefficien t defined as with a two-par amet er form , wher e is the ac entric fac tor. •The P eng-R obinson equa tion [90] (p.4010 ) is a thr ee-par amet er equa tion of sta te, also r equir ing the cr itical temp erature, critical pr essur e and ac entric fac tor par amet ers. It is though t to perform as w ell as the S oave- Redlich-K wong equa tion, with an ad vantage in the pr edic tion of the liquid densities . •The A ungier-R edlich-K wong [8] (p.4005 ) equa tion pr ovides impr oved pr edic tions f or v apor and sup ercritical fluids near the cr itical point, as w ell as f or ma terials with a nega tive value of the ac entric fac tor.The Aungier mo dified f orm is a f our par amet er equa tion and r equir es the cr itical sp ecific v olume in addition to the cr itical temp erature, critical pr essur e and ac entric fac tor. The f ollowing limita tions e xist in ANSY S Fluen t for all cubic equa tion of sta te mo dels: •Pressur e-inlets , mass flo w-inlets , and pr essur e-outlets ar e the only inflo w and outflo w boundar ies a vailable for use with the r eal gas mo dels . •Non-r eflec ting b oundar y conditions ar e not c ompa tible with the r eal gas mo dels when using the densit y- based solv er. If your mo del r equir es NRBC and a r eal gas mo del, you must use the pr essur e-based solv er. •The cubic equa tion of sta te real gas mo dels ar e compa tible with the E uler ian multiphase mo dels . •The cubic equa tion of sta te mo dels ar e compa tible with the Lagr angian D ispersed P hase M odels . If you are mo deling dr oplet or multic omp onen t par ticles , not e tha t the cur rent formula tion do es not tak e into accoun t the near-cr itical point phenomena, which means tha t accur ate results c an b e obtained f or dr oplet Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1158Physical Propertiestemp eratures b elow . See Using the C ubic E qua tion of S tate Models with the Lagr angian D is- persed P hase M odels (p.1171 ) for mor e details . •The r eal gas mo dels ar e not a vailable with the pr emix ed, iner t, and c omp osition PDF tr ansp ort combustion models . •The cubic equa tion of sta te real gas mo dels c an b e used with the f ollowing sp ecies mo dels: –Species tr ansp ort. Chemic al reactions c an b e mo deled with the finit e rate and edd y dissipa tion mo dels . Note tha t the Dimension Reduc tion mo del is not a vailable with the r eal gas mo dels . –Non-pr emix ed mo del and par tially-pr emix ed mo del. Note tha t the Compr essibilit y Effects option must b e enabled in the Species M odel dialo g box in or der f or the r eal-gas mo dels t o be available . In addition the f ollowing r estrictions apply when the non-pr emix ed mo del is used t ogether with a cubic equa tion of sta te real-gas mo del: →The empir ical str eam options c annot b e used , as f or the empir ical sp ecies the cr itical pr operties cannot b e defined . →Condensed sp ecies such as h2o and c ar e not supp orted and should b e excluded fr om the PDF table , so ensur e tha t you add all c ondensed sp ecies f or y our sy stem in the e xcluded sp ecies list prior t o the PDF table gener ation. The laminar flame sp eeds f or the par tially-pr emix ed mo del ar e assumed t o be the same as f or ideal- gases . •When the cubic equa tion of sta te mo dels ar e applied f or sub critical conditions near or under the phase dome , the t wo-phase flo w is not mo deled and either v apor or liquid sta te must b e selec ted. Sub critical and sup ercritical sta tes c an c o-exist in the same simula tion. 8.16.3.2. Equation of Stat e The gener al form of pr essur e P f or the cubic equa tion of sta te mo dels is wr itten as [8] (p.4005 ) : (8.89) wher e P = absolut e pr essur e (P a) V = sp ecific molar v olume ( ) T = t emp erature (K) R = univ ersal gas c onstan t The c oefficien ts , , , , and are giv en f or each equa tion of sta te as func tions of the cr itical temp erature , critical pr essur e , acentric fac tor and cr itical sp ecific v olume . Note tha t the attractive coefficien t also has a t emp erature dep endenc e, which v aries f or each equa tion of sta te model, and is c ommonly wr itten as . Redlich-K wong E qua tion [100] (p.4010 ): (8.90) 1159Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Real G as M odels(8.91) (8.92) The par amet er is set equal t o , while and are set t o 0. The R edlich-K wong equa tion is the simplest of the cubic equa tions of sta te in ANSY S Fluen t and r equir es two par amet ers only , the cr itical temp erature and the cr itical pr essur e . Soave-Redlich-K wong E qua tion [124] (p.4011 ): (8.93) (8.94) and are giv en b y Equa tion 8.91 (p.1160 ) and Equa tion 8.92 (p.1160 ) respectively. As in the or iginal Redlich-K wong equa tion the par amet er is set equal t o , while and are set t o 0. The S oave- Redlich-K wong r equir es thr ee par amet ers, the cr itical temp erature , the cr itical pr essur e , and the ac entric fac tor . Peng-Robinson E qua tion [90] (p.4010 ): (8.95) (8.96) The func tion is giv en b y Equa tion 8.93 (p.1160 ), with n pr ovided in Equa tion 8.97 (p.1160 ) as f ollows: (8.97) In the P eng-R obinson equa tion is set equal t o , is equal t o , and is set t o 0. Similar t o the S oave-Redlich-K wong equa tion, the P eng-R obinson equa tion is a thr ee-par amet er equa tion and r equir es the cr itical temp erature , the cr itical pr essur e , and the ac entric fac tor . Aungier-Redlich-K wong E qua tion [8] (p.4005 ): (8.98) (8.99) and are giv en b y Equa tion 8.91 (p.1160 ) and Equa tion 8.92 (p.1160 ), respectively. As in the or iginal Redlich-K wong equa tion, the par amet er is set equal t o and is set t o 0. Paramet er is giv en b y: (8.100) The A ungier-R edlich-K wong equa tion r equir es four par amet ers, namely the cr itical temp erature , the cr itical pr essur e , the cr itical sp ecific v olume , and the ac entric fac tor . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1160Physical Properties8.16.3.3. Enthalp y, Entropy, and Sp ecific H eat C alculations Enthalp y, entropy, and sp ecific hea t are comput ed in t erms of the r elevant ideal gas pr operties and the depar ture func tions .The depar ture func tion of an y conceptual pr operty is defined as [95] (p.4010 ) (8.101) wher e is the v alue of the pr operty as c omput ed fr om the ideal gas r elations .The depar ture func tion can b e der ived fr om basic ther modynamic r elations and the equa tion of sta te. Following the ab ove definition, the en thalp y for the equa tions of sta te mo dels is giv en b y the f ol- lowing equa tions [8] (p.4005 ): (8.102) (8.103) (8.104) wher e, = ideal gas en thalp y at temp erature T (J/kg) = depar ture en thalp y (J/kmol) = mean molecular w eigh t (Kg/k mol) = pr essur e (P a) = sp ecific molar v olume ( /kmol) = univ ersal gas c onstan t , , and are comput ed using Equa tion 8.90 (p.1159 )– Equa tion 8.100 (p.1160 ) dep ending on the equa tion of sta te mo del See Equa tion 8.89 (p.1159 ) for a descr iption of other c oefficien ts. Similar ly, the depar ture in ternal ener gy can b e sho wn t o be (8.105) wher e = depar ture in ternal ener gy (J/kmol) = temp erature (K) = sp ecific molar v olume ( /kmol) is giv en b y Equa tion 8.104 (p.1161 ) , , and are comput ed using Equa tion 8.90 (p.1159 ) – Equa tion 8.100 (p.1160 ) dep ending on the equa tion of sta te mo del The sp ecific hea t can b e comput ed fr om the ideal sp ecific hea t and the depar ture sp ecific heat at constan t volume as f ollows: 1161Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Real G as M odels(8.106) (8.107) wher e = mean molecular w eigh t (kg/kmol) = pr essur e (P a) = temp erature (K) = sp ecific molar v olume ( /kmol) = univ ersal gas c onstan t In Equa tion 8.107 (p.1162 ) is c omput ed b y diff erentiating the equa tion of depar ture in ternal ener gy (Equa tion 8.105 (p.1161 )) with r espect to , and the par tial der ivatives of the sp ecific v olume ar e comput ed b y diff erentiating Equa tion 8.89 (p.1159 ) appr opriately. The en tropy is c omput ed b y (8.108) (8.109) wher e = ideal gas en tropy at temp erature T and r eference pr essur e (J/kg/K) = ideal gas sp ecific molar v olume a t temp erature T and the r eference pressur e ( /kmol) = pr essur e (P a) = temp erature (K) = sp ecific molar v olume ( /kmol) = mean molecular w eigh t (kg/kmol) is giv en b y Equa tion 8.104 (p.1161 ) and , , and are comput ed using Equa tion 8.90 (p.1159 ) – Equa tion 8.100 (p.1160 ), dep ending on the equa tion of sta te mo del. Note tha t the pr essur e term in Equa tion 8.108 (p.1162 ) cancels out as b oth and are evalua ted a t the r eference pr essur e. 8.16.3.4. Critic al C onstants for P ure Comp onents Equa tions descr ibing r eal-gas pr operties r equir e the k nowledge of the cr itical constan ts for pur e comp onen ts and mix tures.These c onsist of the cr itical temp erature ( ), critical pr essur e ( ), critical specific v olume ( ), and the ac entric fac tor ( ). Several cr itical constan ts for fluid ma terials in the ANSY S Fluen t property da tabase propdb.scm have been c ompiled fr om a v ariety of sour ces a vailable in the op en lit erature [95] (p.4010 ),[86] (p.4009 ), [87] (p.4009 ),[118] (p.4011 ),[119] (p.4011 ),[125] (p.4011 ),[7] (p.4005 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1162Physical PropertiesFor those fluid ma terials, for which the cr itical pr operties ha ve not b een f ound in the op en lit erature, these ha ve been estima ted using the c ommer cially a vailable sof tware CR ANIUM b y Molecular K now- ledge S ystems Inc .[1] (p.4005 ) :http://www.molknow.com/Cranium/cranium.htm Critical pr operty values f or man y hydrocarbon and nitr ogenous r adic al sp ecies ha ve been obtained from Tang and B rezinsk y [131] (p.4012 ).Where the cr itical pr operties f or the r adic als w ere not a vailable in the lit erature, these w ere estima ted using a mo dific ation of the J oback metho d [95] (p.4010 ).This assumes tha t the r adic al sit e constitut es a distinc t group with z ero gr oup c ontribution and utiliz es the gr oup c ontribution v alues f or stable sp ecies . The cr itical pr operties of c oal v olatiles ha ve been estima ted assuming tha t the v olatiles c an b e appr ox- imated b y a mix ture of C O, , , , and in such a w ay, tha t the a tom c omp osition and the net c alor ific v alue of the v olatiles is similar t o tha t of the assumed mix ture.The cr itical pr operties of the lignit e and biomass v olatiles ha ve been assumed equal t o those of f ormaldeh yde.The cr itical properties of diesel and jet-a fuels ha ve been set equal t o those of dec ane.The cr itical pr operties of kerosene ha ve been set equal t o those of do decane. 8.16.3.5. Calculations for M ixtures For the c omputa tion of pr operties in r eal-gas mix tures, ANSY S Fluen t follows the so-c alled pseudo crit- ical metho d. According t o this metho d, the b ehavior and pr operties of a r eal gas mix ture will b e the same as tha t of a pur e comp onen t, to which appr opriate cr itical constan ts ar e assigned .These mix ture critical constan ts ar e func tions of the mix ture comp osition and pur e comp onen t critical pr operties, and ar e sometimes c alled pseudo critical constan ts, because their v alues ar e gener ally e xpected t o be different from the tr ue mix ture cr itical constan ts tha t ma y be det ermined e xperimen tally . However for c omputa tional pur poses the y are the appr opriate cr itical constan t values f or the mix ture. According to the pseudo critical metho d, ANSY S Fluen t applies Equa tion 8.89 (p.1159 )– Equa tion 8.109 (p.1162 ) also for mix tures, wher e the cr itical temp erature , critical pr essur e , critical sp ecific v olume , and acentric fac tor , are replac ed b y the c orresponding mix ture cr itical constan ts, critical temp erature , critical pr essur e , critical sp ecific v olume , and ac entric fac tor . The f ollowing options ar e available in ANSY S Fluen t for the c alcula tion of the mix ture pseudo critical constan ts: •The simplest r ule f or computing the pseudo critical constan ts for a r eal gas mix ture is the mole fr action average [95] (p.4010 ).This metho d is r ecommended f or mix tures wher e the pur e comp onen t critical properties f or all c omp onen ts ar e not v ery diff erent: (8.110) wher e = mix ture pseudo critical constan t (temp erature, pressur e, specific v olume or ac entric fac tor) = cr itical constan t of c omp onen t i (t emp erature, pressur e, specific v olume or ac entric fac tor) = mole fr action of c omp onen t i = numb er of c omp onen ts in mix ture 1163Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Real G as M odels•An alt ernative appr oach is based on the one-fluid v an der Waals mixing r ules as e xpressed in [100] (p.4010 ). According t o this appr oach, in or der t o apply the equa tion of sta te mo dels t o mix tures, the c oefficien ts and in Equa tion 8.89 (p.1159 ) are replac ed b y comp osition-dep enden t expressions as f ollows: (8.111) (8.112) wher e = mole fr action of sp ecies i With the appr opriate expressions fr om Equa tion 8.90 (p.1159 )– Equa tion 8.100 (p.1160 ) for each equa tion of sta te, and assuming a mix ture ac entric fac tor for the e valua tion of par amet er in Equa tion 8.94 (p.1160 ),Equa tion 8.97 (p.1160 ), and Equa tion 8.99 (p.1160 ), the mixing r ules Equa- tion 8.111 (p.1164 ) and Equa tion 8.112 (p.1164 ) can b e rearranged t o yield dir ect expressions of the mixture cr itical pr operties as func tions of the mole fr actions and the c omp onen t critical pr operties [8] (p.4005 ). The r esulting e xpressions f or the mix ture cr itical sp ecific t emp erature are as f ollows: –Soave-Redlich-K wong and P eng-R obinson mo dels (8.113) –Redlich-K wong mo del and A ungier-R edlich-K wong mo del: (8.114) wher e for the A ungier-R edlich-K wong mo del is obtained fr om Equa tion 8.99 (p.1160 ) as func tion of the mix ture ac entric fac tor . For the R edlich-K wong mo del . The mix ture cr itical sp ecific pr essur e is c omput ed as: (8.115) The mix ture cr itical sp ecific v olume is c omput ed as: (8.116) The nota tion f or Equa tion 8.113 (p.1164 ) to Equa tion 8.116 (p.1164 ) is = mix ture pseudo critical temp erature (K) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1164Physical Properties = mix ture pseudo critical pr essur e (P a) = mix ture pseudo critical molar v olume ( /kmol) = cr itical temp erature for c omp onen t i (K) = cr itical pr essur e for c omp onen t i (P a) = cr itical molar v olume f or c omp onen t i ( /kmol) = mole fr action f or c omp onen t i 8.16.3.5.1. Using the C ubic E quation of Stat e Real G as Mo dels For single or multic omp onen t flo ws, you will enable the cubic equa tion of sta te real gas mo dels b y selec ting real-gas-soa ve-redlich-k wong ,real-gas-p eng-r obinson ,real-gas-aungier-r edlich-k wong , or real-gas-r edlich-k wong from the Densit y drop-do wn list in the Create/Edit M aterials dialo g box. Setup → Materials → Create/Edit... The r equir ed inputs f or the cubic equa tion of sta te real gas mo dels f or single c omp onen t flo w and mixtures ar e descr ibed b elow. Single C omp onen t Flow Figur e 8.38: The C ubic E qua tion of S tate M odel f or a Real-G as F luid When an y of the cubic equa tion of sta te mo dels is enabled , enter the f ollowing ma terial pr operties in the dialo g box: 1165Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Real G as M odels•ideal sp ecific hea t •molecular w eigh t •standar d sta te en tropy •reference temp erature •critical temp erature •critical pr essur e •critical sp ecific v olume •acentric fac tor Imp ortant Your inputs f or the sp ecific hea t in the Materials dialo g box will no w b e used t o comput e the ideal pr operty func tions , , and in Equa tion 8.102 (p.1161 ),Equa- tion 8.106 (p.1162 ), and Equa tion 8.108 (p.1162 ), respectively. In ANSY S Fluen t the depar ture properties will b e comput ed and added t o the ideal par t, to yield the r eal gas sp ecific heat, enthalp y, and en tropy. Mixtures Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1166Physical PropertiesFigur e 8.39: The C ubic E qua tion of S tate M odel f or a Real-G as M ixture When one of the cubic equa tion of sta te mo dels is selec ted fr om the Densit y drop-do wn list , specify the f ollowing ma terial pr operties f or the mix ture ma terial in the dialo g box: •ideal sp ecific hea t •critical temp erature •critical pr essur e •critical sp ecific v olume •acentric fac tor You also need t o en ter the f ollowing ma terial pr operties f or each of the mix ture comp onen ts in the dialo g box: •molecular w eigh t •standar d sta te en tropy •reference temp erature When y ou ar e mo deling a r eal-gas mix ture, the f ollowing metho ds ar e available f or the mix ture critical constan ts: 1167Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Real G as M odels•constan t: defines a c onstan t critical temp erature, critical pr essur e, critical sp ecific v olume , or ac entric factor for the mix ture ma terial. •mole-w eigh ted-mixing-la w: applies Equa tion 8.110 (p.1163 ) for cr itical temp erature, critical pr essur e, critical sp ecific v olume , or ac entric fac tor for the mix ture ma terial. •one-fluid-v an-der-w aals-mixing-la w applies Equa tion 8.113 (p.1164 ) and Equa tion 8.114 (p.1164 ) for the mixture critical temp erature (dep ending on the r eal-gas mo del), Equa tion 8.115 (p.1164 ) for the mix ture critical pr essur e, and Equa tion 8.116 (p.1164 ) for the mix ture molar v olume . Imp ortant •Ensur e to click the Change/C reate butt on so tha t all the ab ove men tioned pr operties ar e uploaded and ar e visible in the in terface. •If you ha ve selec ted mixing-la w for the mix ture ideal sp ecific hea t you will also need t o en ter the ideal sp ecific hea t values f or the individual mix ture comp onen ts. If you ha ve not selec ted constan t as the option f or an y of the cr itical pr operties, you must en ter the c orresponding pure comp onen t critical pr operties f or the mix ture comp onen ts. If the op erating c onditions in y our mo del ar e in the sub critical regime , selec t Vapor or Liquid as the Real G as S tate in the Operating C onditions dialo g box (Figur e 8.40: The Op erating C onditions for a R eal G as S tate (p.1168 )). Alternatively, you c an use the define/operating-condi- tions/set-state text command . Note tha t the default is Vapor and ther efore Vapor is assumed if no changes ar e made t o the Real G as S tate settings . If the op erating c onditions in y our mo del are en tirely in the sup ercritical regime , this setting will ha ve no eff ect. Figur e 8.40: The Op erating C onditions f or a Real G as S tate Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1168Physical PropertiesIn addition, you ma y sp ecify the sta te for a sp ecific fluid z one or a sp ecific phase (if y ou ar e using multiphase mo deling) b y typing the f ollowing t ext command a t the ANSY S Fluen t console pr ompt: > define boundary-conditions modify-zones change-zone-state Select a name/id from fluid zones list [(liquid-zone fluid-1)] liquid-zone Set zone real-gas state: -1:use global setting 0:liquid 1:vapor [-1] 0 8.16.3.5.2. Solution Str ategies and C onsider ations for C ubic E quations of Stat e Real G as Mo dels The flo w mo deling of r eal-gas flo w is mor e comple x and challenging than simple ideal-gas flo w. Therefore, the solution migh t converge a t a slo wer rate with r eal-gas flo w than when r unning ideal- gas flo w. It is r ecommended tha t you first a ttempt t o converge y our solution using first-or der dis- cretiza tion then swit ch t o sec ond-or der discr etiza tions and r e-iterate to convergenc e. Special c onsider ations apply if the op erating r egime in y our mo del is fully or par tly sub critical, wher e the ph ysical sta te ma y be vapor, liquid , or a v apor/liquid mix ture. In the cubic EOS r eal-gas mo del, the phase sta te is det ermined b y the selec tion of the cubic r oot to calcula te the molar-v olume .This is illustr ated in Figur e 8.41: The PV D iagr am f or the C ubic E qua tion of S tate Real G as M odel (p.1170 ), which sho ws a pr essur e versus molar v olume (PV ) diagr am, with a sub critical isother m ABFED a t temp erature T calcula ted fr om a cubic EOS. Curve C1C C2 r epresen ts the cr itical isother m and cur ve ACD the sa turation dome . Points A, F, and D r epresen t the thr ee r oots of the EOS a t the sa turation pressur e Ps, wher e A c orresponds t o the molar v olume of sa turated liquid , D t o the molar v olume of sa turated v apor and p oint F do es not ha ve a ph ysical signific ance. Points A1 and D1 c orrespond to the liquid and v apor molar v olumes a t pressur e P1, which is lo wer than the sa turation pr essur e. The liquid and v apor molar v olumes a t pressur e P2, which is higher than the sa turation pr essur e, are mar ked as A2 and D2 r espectively. Points B and E , wher e the par tial der ivatives of pr essur e with respect to volume are 0, are called spino dal p oints.The lo ci of these p oints for all sub crit- ical temp eratures, the spino dal cur ve, is sho wn with the dashed cur ve BCE and sets the b oundar y beyond which the equa tion of sta te is no longer v alid, because the lo cal der ivative of pr essur e with respect to volume b ecomes p ositiv e. State points inside the dome , up t o the spino dal cur ve, are called “metastable ” because nor mally the y only e xist t emp orarily in small lo cal regions un til phase change o ccurs . 1169Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Real G as M odelsFigur e 8.41: The PV D iagr am f or the C ubic E qua tion of S tate Real G as M odel It is imp ortant to realiz e tha t the cur rent implemen tation of the cubic equa tions of sta te real gas model do es not det ermine the sa turation c onditions and do es not mo del the t wo-phase flo w wher e liquid and v apor c oexist. In the sub critical regime and f or c onditions wher e the cubic EOS has thr ee roots, the phase sta te selec tion is c ontrolled b y your input of Vapor or Liquid for Real G as S tate in the Operating C onditions dialo g box (Figur e 8.40: The Op erating C onditions f or a R eal G as State (p.1168 )).The default setting is Vapor, which c orresponds t o the sta te points to the r ight of the vapor spino dal. With r eference to Figur e 8.41: The PV D iagr am f or the C ubic E qua tion of S tate Real Gas M odel (p.1170 ), for the op erating p oint at temp erature T and pr essur e P1, if the Real G as S tate is set t o Vapor, the molar v olume a t point D1, which c orresponds t o sup erheated v apor, will b e se- lected in the c alcula tion. On the other hand , if y ou ha ve selec ted Liquid , the molar v olume of p oint A1 will b e tak en, and the c orresponding sta te will b e metastable sup erheated liquid . Similar ly for pressur e P2, which is higher than the sa turation pr essur e Ps, if y ou selec t Liquid for Real G as S tate, the liquid molar v olume a t A2 will b e comput ed, and if y ou selec t Vapor the molar v olume will correspond t o the sub cooled v apor sta te point D2. In case the c alcula tions fall inside the sa turation dome , the solv er will not limit the solution, but if conditions ar e pr edic ted tha t extend b eyond the v apor spino dal cur ve a w arning will b e issued: temperature is below the spinodal point in 12 cells on zone 3. Cubic equa tions of sta te real gas mo dels ar e not a vailable f or two-phase flo ws but c an b e applied to conditions of sup ercritical pr essur e and sub critical temp erature , wher e the fluid is in the liquid sta te, and the sup ercritical liquid c o-exists with gas and sup ercritical fluid in the same Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1170Physical Propertiessimula tion. In those c ases , phase change ma y tak e plac e, without an y of the flo w conditions falling inside the sa turation dome . For multic omp onen t simula tions , when Diffusion E nergy Sour ce is enabled in the Species M odel dialo g box, the sp ecies ener gy diffusion is b y default suppr essed in the sup ercritical liquid r egime and acr oss the gas-liquid b oundar y.The diffusion ener gy sour ce can b e included in the liquid r egime using the define/models/species/liquid-energy-diffusion? text command . 8.16.3.5.3. Using the C ubic E quation of Stat e Mo dels with the L agr angian D ispersed Phase Mo dels If your simula tion c ontains a liquid str eam, the appr opriate mo deling appr oach in the v arious op er- ating c ondition r egimes is as f ollows: 1.For a liquid phase do es not e xist. 2.In the r egion , you c an define the flo w str eams dir ectly in the b oundar y conditions b y setting the appr opriate pr essur e and t emp erature and the pr operties will b e comput ed dir ectly b y the cubic EOS. 3.For or , a str eam c an e xist in liquid phase when its t emp erature . If you w ould lik e to model phase change in this r egime , the f ollowing r ecommenda tions apply : •The DPM dr oplet and multic omp onen t mo dels ar e adequa te and r ecommended f or the c onditions away from the cr itical point.This r egime c an b e defined as , wher e the liquid ph ysical properties c an b e assumed indep enden t of pr essur e. •The r egion is char acterized b y near-cr itical-p oint phenomena, such as str ong liquid densit y and sp ecific hea t dep endenc e on b oth t emp erature and pr essur e.The DPM mo del c an also be used in this r egime , but y ou should b e cautious , as it will not tak e into consider ation the near- critical-p oint behavior. In addition, the applic abilit y of the e vaporation and b oiling r ate equa tions is questionable in this r egime . •If the pr essur e in y our mo del is ab ove the cr itical point, it is r ecommended t o use the compr essible- liquid metho d for Densit y of the dr oplet ma terial. The t emp erature gives an indic ation of the maximum dr oplet t emp erature for applic ab- ility of the DPM mo dels f or each dr oplet ma terial.These t emp erature limits ar e list ed in Table 8.2: Temp erature Limits f or D roplet M aterials in ANSY S Fluen t Database pr odb.scm (p.1171 ) for man y of the dr oplet ma terials in ANSY S Fluen t's propdb.scm ma terials da tabase . For sup ercritical pressur es ( ), the DPM mo dels c an still b e used pr ovided the dr oplet t emp eratures remain b elow the limit . Table 8.2: Temp erature Limits f or D roplet M aterials in ANSY S Fluen t Database pr odb.scm Tlim (K) Normal BP (K) Pc (MP a) Tc (K) Material 135.77 87.30 4.89 150.86 Argon 505.80 353.00 4.89 562.00 Benzene 4.77 4.20 0.23 5.30 Helium 29.68 20.40 1.30 32.98 Hydrogen 460.80 338.00 8.10 512.00 Methyl-alc ohol 486.80 371.00 2.74 540.00 Heptanes 1171Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Real G as M odels456.30 342.00 3.02 507.00 Hexane 512.10 399.00 2.49 569.00 Octane 423.00 309.00 3.37 470.00 Pentane 113.40 77.40 3.40 126.00 Nitrogen 138.60 90.20 5.04 154.00 Oxygen 532.80 384.00 4.11 592.00 Toluene 582.30 373.00 22.00 647.00 Water For high pr essur e simula tions the b oiling p oint will b e diff erent from the nor mal b oiling p oint, and for v arying pr essur e applic ations the b oiling p oint will v ary with the dr oplet lo cation in the domain. When a cubic equa tion of sta te real gas mo del is enabled in a simula tion tha t includes e vaporating droplet par ticles , the b oiling p oint is c alcula ted fr om the v apor pr essur e da ta dir ectly, as the t emp er- ature wher e the sa turation v apor pr essur e equals the domain pr essur e. In addition, the la tent hea t of the e vaporating or b oiling dr oplet will v ary with the dr oplet t emp erature. The la tent hea t at temp erature is giv en b y (8.117) wher e is the nor mal b oiling p oint and is the la tent hea t at the nor mal b oiling p oint. In the Create/Edit M aterials dialo g box you must en ter the Normal B oiling P oint (NBP) and the Latent Heat at NBP for the droplet-par ticle Material Type.These inputs will b e used f or c alcula ting the Latent Heat at the r eference temp erature (see Equa tion 16.470 ) and the la tent hea t in the dr oplet ener gy balanc e dur ing v aporization and b oiling acc ording t o Equa tion 8.117 (p.1172 ). Imp ortant The c onstan t property option is disabled f or the Saturation Vapor P ressur e property when a r eal gas mo del is used in the simula tion. Also, ensur e to en ter the appr opriate droplet sa turation v apor pr essur e da ta to cover the c omplet e pr essur e/temp erature range in y our mo del. Finally when a cubic equa tion of sta te real-gas mo del is enabled in a simula tion with dr oplet mo dels , the c ondition f or swit ching fr om the v aporization t o the b oiling la w will b e (8.118) wher e is the sa turation v apor pr essur e and P is the domain pr essur e. If while in the boiling la w, the mo del will swit ch back t o the v aporization la w. Under sup ercritical pr essur e conditions ( ), the v aporization mo dels ar e applic able a t droplet t emp eratures b elow the cr itical p oint, and the swit ching c ondition fr om v aporization t o boiling is ne ver met b ecause the v apor pr essur e curve is defined only up t o the cr itical p oint. For the multic omp onen t droplets in the sup ercritical pr essur e regime , failur e of the sa turation t em- perature calcula tion algor ithm ma y indic ate tha t the dr oplet has appr oached the cr itical temp erature, provided tha t you ha ve en tered accur ate vapor pr essur e da ta for all c omp onen ts. In such a c ase, you c an use the f ollowing t ext command: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1172Physical Propertiesdefine/models/dpm/options/treat-multicomponent-saturation-temperature- failure? Dump multicomponent particle mass if the saturation temperature calcu- lation fails? [no] y When this option is enabled , ANSY S Fluen t dumps the par ticle mass in to the c ontinuous phase if the sa turation t emp erature calcula tion fails . 8.16.3.5.4. Postpr ocessing the C ubic E quations of Stat e Real G as Mo del All postpr ocessing func tions pr operly report and displa y the cur rent ther modynamic and tr ansp ort properties of the selec ted r eal gas mo del. The ther modynamic and tr ansp ort properties c ontrolled by the cubic equa tions of sta te real gas mo del include the f ollowing: •densit y •enthalp y •entropy •sound sp eed •specific hea t •any quan tities tha t are der ived fr om the pr operties list ed ab ove (for e xample , total quan tities , ratio of specific hea ts) In addition t o the pr operties list ed ab ove, you c an also r eport •compr essibilit y fac tor •reduc ed t emp erature •reduc ed pr essur e •spino dal t emp erature •subcritical condition If you ar e mo deling a r eal-gas mix ture you c an r eport the c omp osition-dep enden t mix ture cr itical properties •critical temp erature •critical pr essur e •critical sp ecific v olume •acentric fac tor 8.16.4. The NIST Real G as M odels The NIST r eal gas mo dels use the N ational Institut e of S tandar ds and Technolo gy (NIST ) Thermodynamic and Transp ort Properties of R efriger ants and R efriger ant Mixtures D atabase Version 9.1 (REFPR OP v9.1) 1173Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Real G as M odelsto evalua te ther modynamic and tr ansp ort properties of appr oxima tely 125 fluids or a mix ture of these fluids . The REFPR OP v9.1 da tabase is a shar ed libr ary tha t is d ynamic ally loaded in to the solv er when y ou enable one of the NIST r eal gas mo dels in an ANSY S Fluen t session. Onc e the NIST r eal gas mo del is activated, control of r elevant property evalua tions is r elinquished t o the REFPR OP da tabase . All post- processing func tions will pr operly report and displa y the cur rent ther modynamic and tr ansp ort prop- erties of the r eal gas . 8.16.4.1. Limitations of the NIST R eal G as Mo dels The f ollowing limita tions e xist f or the NIST r eal gas mo del: •When y ou ar e using the NIST r eal gas mo dels , the NIST ma terials defined in y our simula tion will app ear in the Create/Edit M aterials D ialog Box (p.3386 ) either with the name real-gas-_name , wher e _name is the NIST ma terial selec ted f or the single sp ecies mo del, or with the name real-gas-mix ture for the multiple species mo del. The inputs f or the pr operties c alcula ted b y the NIST func tions ar e disabled .You c an use the Create/Edit M aterials D ialog Box (p.3386 ) to define or mo dify : –Mass diffusivit y pr operty in the real-gas-mix ture material if y ou ar e using the multiple-sp ecies NIST real gas mo del (not e tha t the kinetic-theor y option is not a vailable) –Radia tion pr operties if y ou ar e mo deling r adia tion –Properties of ma terials other than the NIST real-gas-mix ture or real-gas-fluid materials •The NIST r eal gas mo del assumes tha t the fluid y ou will b e using in y our ANSY S Fluen t computa tion is superheated v apor, sup ercritical fluid , or liquid . Note tha t sub critical flo w conditions , wher e vapor coexists with liquid in t wo-phase flo w, are not supp orted. In addition, all fluid z ones must c ontain the r eal gas; you c annot include a r eal gas and another fluid in the same pr oblem. •Pressur e-inlet , mass flo w-inlet , and pr essur e-outlet ar e the only inflo w and outflo w boundar ies a vailable for use with the r eal gas mo dels . •Non-r eflec ting b oundar y conditions ar e not c ompa tible with the r eal gas mo dels when using the densit y- based solv er. If your mo del r equir es NRBC and a r eal gas mo del, you must use the pr essur e-based solv er. •The mix ture flo w do es not p ermit chemic al reactions with the NIST r eal gas mo del. •The multic omp onen t NIST r eal gas mo dels c annot b e used with an y of the multiphase mo dels .You c an, however, use a NIST ma terial in single-c omp onen t multiphase flo ws.The mo del is c ompa tible with the Lagr angian D ispersed P hase M odels only f or the massless and iner t par ticle t ypes. •You c annot mo dify ma terial pr operties in the REFPR OP da tabase libr aries, or add cust om ma terials t o the NIST r eal gas mo del. •The Diffusion E nergy Sour ce in the ener gy equa tion (see The Ener gy Equa tion in the Theor y Guide ) is not included with the nist-multisp ecies-r eal-gas-mo dels and the pr essur e-based solv er. 8.16.4.2. The REFPR OP v9.1 D atabase The NIST r eal gas mo del supp orts 125 fluids fr om the REFPR OP da tabase .These include pur e fluids (with the file e xtension .fld ) and pseudo-fluids (with the file e xtension .ppf ).The fluids tha t are Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1174Physical Propertiessupp orted b y REFPR OP v9.1 and used in the NIST r eal gas mo del ar e list ed in Table 8.3: Fluids Supp orted by REFPR OP v9.1 (p.1175 ) (the c orresponding pr operty file name app ears in par entheses , wher e it do es not c oincide with the fluid name). The REFPR OP v9.1 da tabase emplo ys accur ate pur e-fluid equa tions of sta te tha t are available fr om NIST .These equa tions ar e based on thr ee mo dels: •modified B enedic t-Webb-R ubin (MB WR) equa tion of sta te •Helmholtz-ener gy equa tion of sta te •extended c orresponding sta tes (ECS) For a fluid tha t consists of a multisp ecies-mix ture the ther modynamic pr operties ar e comput ed b y emplo ying mixing-r ules applied t o the H elmholtz ener gy of the mix ture comp onen ts. Imp ortant The da tabase do es not include tr ansp ort property mo dels f or the sp ecies mar ked with * in Table 8.3: Fluids Supp orted b y REFPR OP v9.1 (p.1175 ). As a r esult the NIST r eal gas mo del with those sp ecies c an only b e used f or mo deling in viscid flo w. Table 8.3: Fluids S upp orted b y REFPR OP v9.1 nitrogen 1-but ene nonane propanone (ac etone .fld) Dodecafluor o-2-meth ylpentan-3-one (no vec649.fld) air octane ammonia orthoh ydrogen (or thoh yd.fld)* argon oxygen benzene 1,2-dimeth ylbenzene (o xylene .fld)* n-butane (butane .fld) parahydrogen (par ahyd.fld) dodecane (c12.fld) pentane meth ylcyclohe xane (c1cc6.fld) propane cis-2-but ene (c2but ene.fld) propene (pr opylen.fld) n-pr opylcyclohe xane (c3cc6.fld) propyne decafluor obutane (c4f10.fld) 1,4-dimeth ylbenzene (px ylene .fld)* dodecafluor o-pentane (c5f12.fld) 1,1,2-tr ichlor o-1,2,2-tr ifluor o-ethane (r113.fld) trifluor o-io do-methane (cf3i.fld) 1,2-dichlor o-1,1,2,2-t etrafluor o-ethane (r114.fld) carbondio xide chlor o-pentafluor o-ethane (r115.fld) carbonmono xide hexafluor o-ethane (r116.fld) carbono xidesulfide (c os.fld)* trichlor o-fluor o-methane (r11.fld) cyclohe xane (c yclohe x.fld) hexafluor o-pr opene (r1216.fld) cyclop entane (c yclop en.fld) 1-chlor o-3,3,3-tr ifluor oprop-1-ene (r1233z d.fld) cyclopr opane (c yclopr o.fld) 2,3,3,3-t etrafluor oprop-1-ene (r1234yf .fld) deut erium (d2.fld) trans-1,3,3,3-t etrafluor o-pr opene (r1234z e.fld) deut eriumo xide (d2o .fld) 1175Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Real G as M odels2,2-dichlor o-1,1,1-tr ifluor o-ethane (r123.fld) octameth yl-cyclotetra-silo xane (d4.fld) 1-chlor o-1,2,2,2-t etrafluor o-ethane (r124.fld) decameth yl-cyclop entasilo xane(d5.fld) pentafluor o-ethane (r125.fld) dodecameth yl-cyclohe xasilo xane (d6.fld) dichlor o-difluor o-methane (r12.fld) decane 1,1,1,2-t etrafluor o-ethane (r134a.fld) dieth ylether (dee .fld)* chlor otrifluor o-methane (r13.fld) dimeth ylest ercarbonic acid (dmc .fld) 1,1-dichlor o-1-fluor oethane (r141b .fld) metho xymethane (dme .fld) 1-chlor o-1,1-difluor o-ethane (r142b .fld) phen ylethane (eb enzene.fld)* 1,1,1-tr ifluor oethane (r143a.fld) ethane tetrafluor omethane (r14.fld) ethyl alc ohol (ethanol.fld) 1,1-difluor oethane (r152a.fld) ethene (eth ylene .fld) fluor oethane (r161.fld) fluor ine octa-fluor o-pr opane (r218.fld) hydrogen sulfide (h2s .fld) dichlor o-fluor o-methane (r21.fld) hydrogen chlor ide (hcl.fld)* 1,1,1,2,3,3,3-hepta-fluor o-pr opane (r227ea.fld) helium chlor o-difluor o-methane (r22.fld) heptane 1,1,1,2,3,3-he xafluor o-pr opane (r236ea.fld) hexane 1,1,1,3,3,3-he xafluor o-pr opane (r236fa.fld) hydrogen (nor mal) trifluor o-methane (r23.fld) 2-meth yl-1-pr opene (ibut ene.fld) 1,1,2,2,3-p entafluor o-pr opane (r245c a.fld) 2-meth ylpentane (ihe xane .fld) 1,1,1,3,3-p entafluor o-pr opane (r245fa.fld) 2,2,4-tr imeth ylpentane (io ctane .fld) difluor o-methane (r32.fld) 2-meth ylbutane (ip entane .fld) 1,1,1,3,3-p entafluor o-butane (r365mf c.fld) 2-meth ylpr opane (isobutan.fld) 44% R125/4% R134a/52% R143a (r404a.ppf )* krypton 23% R32/25% R125/52% R134a (r407c .ppf )* decameth yl-tetrasilo xane (md2m.fld) meth yl chlor ide (r40.fld)* dodecameth yl-p entasilo xane (md3m.fld) 50% R32/50% R125 (r410a.ppf )* tetradec ameth yl-he xasilo xane (md4m.fld) fluor o-methane (r41.fld) octameth yl-tr isilo xane (mdm.fld) 50% R125/50% R143a (r507a.ppf )* methane octafluor o-cyclobutane (r c318.fld) methanol meth yl tr ifluor o-meth yl ether (r e143a.fld)* meth yl (Z,Z)-9,12-o ctadec adienoa te (mlinolea.fld) meth yl-p entafluor o-eth yl-ether (r e245cb2.fld) meth yl (Z,Z,Z)-9,12,15-o ctadec atrienoa te (mlinolen.fld) 2,2,2-tr ifluor oethyl-difluor ometh yl-ether (r e245fa2.fld) hexameth yl-disilo xane (mm.fld) meth yl-heptafluor o-pr opyl-ether (r e347mcc .fld) meth yl cis-9-o ctadec enoa te (molea te.fld) sulfur he xafluor ide (sf6.fld) meth yl he xadec anoa te (mpalmita.fld) sulfur dio xide (so2.fld) meth yl octadec anoa te (mst earat.fld) trans-2-but ene (t2but ene.fld) 1,3-dimeth ylbenzene (mx ylene .fld) meth ylbenzene (t oluene .fld) dinitr ogen mono xide (n2o .fld) water neon Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1176Physical Propertiesxenon 2,2-dimeth ylpr opane (neop entn.fld) nitrogen tr ifluor ide (nf3.fld)* 8.16.4.3. Using the NIST R eal G as Mo dels When y ou enable one of the NIST r eal gas mo dels (pur e fluid or multiple-sp ecies mix ture) and selec t a valid ma terial, ANSY S Fluen t’s func tionalit y remains the same as when y ou mo del fluid flo w and heat transf er using an ideal gas , with the e xception of the Create/Edit M aterials D ialog Box (p.3386 ). 8.16.4.3.1. Activating the NIST R eal G as Mo del Activating one of the NIST r eal gas mo dels is a t wo-st ep pr ocess. First y ou enable either the single- or multi-sp ecies NIST r eal gas mo del, and then y ou selec t the fluid ma terial fr om the REFPR OP database . 1.Enable the appr opriate NIST r eal gas mo del b y typing the f ollowing t ext command a t the ANSY S Flu- ent console pr ompt: •Pure fluid r eal gas mo del: > define/user-defined/real-gas-models/nist-real-gas-model use NIST real gas? [no] yes •Multi-sp ecies r eal gas mo del: > define/user-defined/real-gas-models/nist-multispecies-real-gas-model use multispecies NIST real gas? [no] yes The list of a vailable pur e fluid ma terials y ou c an selec t from will b e displa yed. 2.Selec t ma terial fr om the REFPR OP da tabase list: •Pure fluid r eal gas mo del: Enter the name of a single pur e fluid tha t you w ant to in vestiga te as f ollows: select real-gas data file [""] methane.fld •Multi-sp ecies r eal gas mo del: Enter the numb er of desir ed sp ecies in the mix ture: Number of species [] 3 followed b y the name of each fluid in quota tion mar ks selec ted fr om the list pr inted in the console: select real-gas data file [""] nitrogen.fld select real-gas data file [""] co2.fld select real-gas data file [""] methane.fld 1177Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Real G as M odelsa.Upon selec tion of a v alid pur e or multi-sp ecies fluids , ANSY S Fluen t will load the r elevant ma terial data fr om a libr ary of pur e fluids supp orted b y the REFPR OP da tabase , and r eport tha t it is op ening the shar ed libr ary (librealgas.so ) wher e the c ompiled REFPR OP da tabase sour ce code is located. A list of pr operties f or the sp ecified ma terial, including its applic able pr essur e and t em- perature ranges , will also b e reported in the c onsole . Imp ortant –For mix ture flo ws, not all c ombina tions of sp ecies mix tures ar e allo wed.This c ould b e due t o lack of da ta for one or mor e binar y pairs . In such situa tions an er ror message gener ated b y NIST will b e retur ned and displa yed on the ANSY S Fluen t console , and no real gas ma terial is allo wed t o be created. In some c ombina tions the mixing da ta will be estima ted, a w arning message will b e displa yed on the ANSY S Fluen t console and the mix ture ma terial allo wed t o be created. –Transp ort property calcula tions ar e not supp orted f or mix tures tha t include w ater with molar c oncentration o ver 5%. If this limit is e xceeded in y our c alcula tion, ANSY S Fluen t will issue a w arning message .Transp ort equa tions ar e not a vailable f or the ammonia/w a- ter mix ture and f or mix tures with alc ohols . As a r esult , the NIST r eal gas mo del with those mix tures c an only b e used f or mo deling in viscid flo w. 3.If you w ant to use NIST lo okup tables in y our simula tion, you c an cr eate them as descr ibed in the f ol- lowing sec tions: •Creating F ull NIST L ook-up Tables (p.1178 ) (single and multi-sp ecies ma terials with ther mal pr operties as w ell as sa turation da ta for a fix ed multi-sp ecies c omp osition) •Creating B inar y Mixture Saturation Tables f or B inar y Mixtures (p.1181 ) (binar y mix tures only) 4.(cases with no NIST tables only) I f you w ould lik e to mo del flo w in the liquid sta te, you c an use the set- state TUI c ommand . Note tha t the default sta te is v apor, so if y ou do not go thr ough this st ep, vapor is assumed . Also, if the flo w conditions do not p ermit liquid t o exist, a vapor calcula tion will b e performed instead. > define/user-defined/real-gas-models/set-state Select vapor state (else liquid)?[yes] In addition, you ma y sp ecify the sta te for a sp ecific fluid z one or a sp ecific phase (if y ou ar e using the multiphase mo del) b y typing the f ollowing t ext command a t the ANSY S Fluen t console prompt: > define boundary-conditions modify-zones change-zone-state Select a name/id from fluid zones list [(liquid-zone fluid-1)] liquid-zone Set zone real-gas state: -1:use global setting 0:liquid 1:vapor [-1] 0 8.16.4.3.2. Creating F ull NIST L ook-up Tables By default , the NIST func tions ar e called dir ectly each time the ther mal pr operties ar e up dated dur ing iteration. Alternatively, you c an use the NIST lo ok-up tables in y our simula tion as descr ibed b elow. Computing the lo ok-up table off ers t wo ad vantages: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1178Physical Properties•Reduc tion in c omputa tion time b ecause the NIST func tions do not need t o be called each time the ther mal pr operties ar e up dated •The lo ok-up table cr eated is applic able t o both liquid and v apor phases To cr eate a full NIST lo ok-up table , first enable the NIST r eal gas mo del as descr ibed in Activating the NIST R eal G as M odel (p.1177 ), and then f ollow these st eps: 1.When pr ompt ed with Create Full NIST LookUp Tables for multi components? [no] , answ er yes . 2.Specify par amet ers f or the lo ok-up table gener ation. For b oth single- and multi-sp ecies r eal gas mo dels , you need t o sp ecify : •Pressur e and t emp erature bounds f or the table You must ensur e tha t the t emp erature and pr essur e bounds y ou sp ecify ar e str ictly within the stated limits of applic abilit y tha t are displa yed when the NIST mo del is loaded . •Numb er of pr essur e, temp erature, and sa turation p oints, which det ermines the r esolution of the property look-up table The minimum numb er of pr essur e and t emp erature points is 12 and ther e is no upp er limit. However, the lar ger the table , the gr eater the memor y and c omputing time r equir emen ts. Use a few t est r uns t o str ike the b est balanc e of c osts (memor y and c omputing time) and accur acy. For multi-sp ecies , you will also need t o sp ecify : •Upper and lo wer molar densit y bounds f or bubble and dew p oint calcula tions Molar densit y is used t o build the sa turation table .The default v alues w ork well for most comp ositions . •The mix ture comp osition on a mass or mole basis You must ensur e tha t the sum of all c onstituen t fractions adds up t o 1 when sp ecifying mass/molar fr actions f or the c omp onen ts.The maximum numb er of sp ecies is 20. •The bubble p oints and dew p oints filenames and the dir ectory wher e you w ant to store the files . Examples of inputs f or the NIST lo ok-up tables: •Pure fluid r eal gas mo del: Min Pressure Value For NIST Table (pa) [13200] Max Pressure Value For NIST Table (pa) [20000] 1000000 Min Temperature Value For NIST Table (k) [237.3] Max Temperature Value For NIST Table (k) [500] 400 Number of Pressure Points For NIST Table [101] Number of Temperature Points For NIST Table [101] Number of Saturation Points For Bubble/Dew Curve [300] NIST table created! Properties for both liquid and vapor phases included! Tcrit = 3.391730e+02 pcrit = 3.617700e+06 Dcrit = 5.735823e+02 Ttrp = 1.725200e+02 •Multi-sp ecies r eal gas mo del: 1179Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Real G as M odelsMin Pressure Value For NIST Table (pa) [130000] Max Pressure Value For NIST Table (pa) [5000000] Min Temperature Value For NIST Table (k) [220] 180 Max Temperature Value For NIST Table (k) [490] 600 Number of Pressure Points For NIST Table [101] Number of Temperature Points For NIST Table [101] Please Select Mass Fractions [Y] or Molar Fractions [N] for Composition of Fluid [yes] Composition of Fluid will be set in Mass Fractions! co2.fld [0.4] methane.fld [0.4] 0.6 Create NIST Saturation Curves for the same multi components? [no] y Number of Saturation Points For Bubble/Dew Curve [300] 22 Min Molar Density For Bubble and Dew Points Calculations (mol/l) [0.1] Max Molar Density For Bubble and Dew Points Calculations (mol/l) [25] Bubble Points File Name ["Bubble_PT.xy"] Dew Points File Name ["Dew_PT.xy"] Directory to store Saturation Files [""] Start NIST Look-Up Table Calculations ... Property Table... 83.3 percent completed! NIST table for 2-components created! Properties for both liquid and vapor phases included! End NIST Look-Up Table Calculations Use the created NIST Lookup Table for thermal property calculations? [no] y Onc e the table is cr eated, you must c onfir m tha t you w ant to use the lo ok-up table f or ther mal properties c alcula tions when pr ompt ed. Use the created NIST Lookup Table for thermal property calculations? [no] yes The created NIST Lookup Table will be used to calculate the thermal properties! If properties ar e needed a t conditions outside the limits y ou ha ve sp ecified f or the table , Fluen t will aut oma tically c all the or iginal NIST mo del func tions t o calcula te the ther mal pr operties. If mor e than 10% of the pr operty evalua tions r equir e computa tion outside the lo ok-up table , Fluen t will pr int a message indic ating the p ercentage of c alcula tions using dir ect computa tion. This c an be used as an indic ator to adjust the t emp erature and pr essur e ranges f or the table t o minimiz e the c omputa tional c ost. For multi-sp ecies r eal gas pr operties, the f ollowing tables will b e created: •fluid pr operties •saturation c onditions Remarks and Limitations on Using Multi-Sp ecies F ull NIST lo ok-up Tables •The lo ok-up table is not sa ved with the c ase file . If you r estar t Fluen t or r e-read c ase and da ta files in to the cur rent Fluen t session, the table will b e clear ed and y ou must go thr ough the st eps ab ove to re-cr eate it before running a simula tion. •For computa tion of sa turation pr operties f or the bubble and dew p oints for a single- or multiple-sp ecies , Fluen t provides macr os tha t you c an use in UDFs . See NIST R eal G as S aturation P roperties in the Fluent Customization Manual for mor e inf ormation. •The tables apply f or compr essible fluids with ma terial pr operties tha t are a func tion of lo cal pr essur e and temp erature.The ma terial pr operties c overed b y the table include fluids in the liquid and v apor phases . The flashing applic ations b etween liquid and v apor phases c an b e conduc ted using sa turation c onditions established f or the fluid(s) using mass tr ansf er mo dels . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1180Physical Properties•The pr operty look-up tables and sa turation tables ar e created f or fix ed fluid c omp ositions .This means the lo ok-up tables ar e based on the f ollowing assumptions: –Mixture comp osition is c onstan t –No chemic al reactions ar e involved –No mixing of fluids of diff erent comp ositions , including no mixing b etween phases •The lo ok-up table only applies t o single-sp ecies/multi-sp ecies in single-phase flo ws. •The t emp erature and pr essur e bounds must b e sp ecified within the sta ted limits of applic abilit y tha t are displa yed when the NIST mo del is loaded . •When sp ecifying the table siz e, it is imp ortant to pick t emp erature and pr essur e ranges tha t are lar ge enough t o sa tisfy the cur rent flo w conditions . •If the t emp erature and pr essur e ranges y ou sp ecify ar e too nar row, Fluen t uses the NIST mo del t o calcula te the ther mal pr operties.The time sa ved b y creating the table will b e nega ted if the p ercentage of c alcu- lations p erformed outside of the table is gr eater than 10%. This p ercentage is pr inted, so y ou c an use it as an indic ator for adjusting the t emp erature and pr essur e range of the table . •For multi-sp ecies table , the bubble and dew p oints ar e sa ved in to files(F luen t plot file f ormat) called Bubble_PT.xy and Dew_PT.xy in the w orking dir ectory. •The lo ok-up table is a str uctured table and ma y not b e suitable f or simula ting flo w behaviors near the critical point when higher r esolution is r equir ed. 8.16.4.3.3. Creating B inar y M ixture Satur ation Tables for B inar y M ixtures To cr eate a sa turation da ta lo ok-up table f or binar y sp ecies mix tures (mix tures of t wo sp ecies only), first enable the NIST r eal gas mo del as descr ibed in Activating the NIST R eal G as M odel (p.1177 ) and then f ollow these st eps: 1.When pr ompt ed with Create Full NIST LookUp Tables for multi components? [no] , answ er no. 2.When pr ompt ed with Create Saturation Table For Binary Mixture Only? [no] , answ er yes . Imp ortant Not all binar y mix tures c an b e comput ed fr om the F luen t built-in NIST mo del. The al- lowed c ombina tion of ma terials is det ermined b y the cur rent da tabase of NIST tha t can b e found in hmx.bnc in the ANSY S Fluen t installa tion dir ectory. 3.Specify par amet ers f or the binar y sa turation da ta lo ok-up table gener ation: •The numb er of sa turation cur ves •The numb er of p oints for each sa turation cur ve 1181Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Real G as M odelsThe default numb er is 12. The ac tual numb er of p oints for each bubble and dew cur ve ma y be diff erent than sp ecified b ecause the NIST mo del ma y not yield v alid c omputa tion r esults for e very densit y point for a giv en mass fr action. •Upper and lo wer molar densit y bounds f or bubble and dew p oint calcula tions The molar densit y is used t o build the sa turation table .You should pr ovide r easonable v alues for the minimum and maximum molar densities c orresponding t o gas phase a t low pr essur e and high t emp erature, and liquid phase a t high pr essur e and lo w temp erature.The default values (as sho wn in the e xample b elow) ar e a go od star ting p oint.You ma y need t o adjust these v alues if ther e is not enough da ta in the selec ted r ange . •The filenames f or bubble p oints and dew p oints and the e xisting dir ectory wher e you w ant to store the files . An example of inputs f or the NIST binar y look-up table: Number of Mass Fraction Points For Binary Mixture [12] Number of Saturation Points For Bubble/Dew Curve [12] Min Molar Density For Bubble and Dew Points Calculations (mol/l) [0.1] Max Molar Density For Bubble and Dew Points Calculations (mol/l) [25] Bubble Points File Name ["Bubble_PT.xy"] Dew Points File Name ["Dew_PT.xy"] Directory to store Saturation Files [""] out The lo okup table builds multiple sets of the bubble and dew p oints for the binar y mix ture with mass fr actions f or the first c omp onen t between 0 and 1. The sec ond c omp onen t mass fr action is equal t o the first c omp onen t mass fr action subtr acted fr om unit y.The numb er of sa turation curves is det ermined b y the numb er of mass fr action p oints tha t you sp ecified . Onc e the lo okup table is cr eated, Fluen t saves the bubble and dew p oints da ta in to files and directory you sp ecified . NIST B inar y Satur ation F iles NIST binar y sa turation files st ore sa turation da ta lo okup table f or bubble and dew p oints for a binar y mixture with mass fr actions b etween 0 and 1. They can b e used f or mass and hea t transf er mo deling involving phase changes . The binar y sa turation file str ucture is as f ollows.The file c ontains se veral da ta sets f or bubble/dew point cur ves for a ser ies of mass fr actions . Each da ta set c onsists of the f ollowing thr ee par ts: 1.Line 1: The mass fr action of the first sp ecies (a single floa t numb er b etween 0 and 1). 2.Line 2: The numb er of da ta pairs f or sa turation pr essur e and t emp erature. 3.The sp ecified numb er of lines tha t follow line 2: Data pairs of sa turation pr essur e and t emp erature.The last pr essur e-temp erature pair c orresponds t o the cr itical condition. The e xample b elow sho ws the sa turation dew p oint da ta for the first t wo cur ves, both with 12 pressur e-temp erature pairs .The first da ta set is f or 0 and the sec ond is f or a 0.083333 mass fr action of the first sp ecies .The pr essur e-temp erature cr itical condition is (4.872200e+06, 3.053220e+02) f or the first cur ve and (5.547305e+06, 2.947561e+02) f or the sec ond cur ve. 0.000000 12 1.142108e+00 9.036800e+01 7.314020e+01 1.099093e+02 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1182Physical Properties1.202771e+03 1.294505e+02 8.833626e+03 1.489918e+02 3.890130e+04 1.685331e+02 1.219542e+05 1.880744e+02 3.025174e+05 2.076156e+02 6.354397e+05 2.271569e+02 1.182515e+06 2.466982e+02 2.011733e+06 2.662395e+02 3.201942e+06 2.857807e+02 4.872200e+06 3.053220e+02 0.083333 12 1.509489e+05 1.891238e+02 1.257388e+06 2.428513e+02 2.252097e+06 2.631615e+02 3.090473e+06 2.752623e+02 3.775539e+06 2.831498e+02 4.318958e+06 2.883822e+02 4.735586e+06 2.917723e+02 5.042345e+06 2.938262e+02 5.258091e+06 2.949048e+02 5.402834e+06 2.952901e+02 5.495209e+06 2.951982e+02 5.547305e+06 2.947561e+02 ..... ..... 8.16.4.3.4. Changing the REFPR OP Libr ary and F luid F iles In ANSY S Fluen t, you c an change the REFPR OP libr ary and the fluid files tha t are acc essed b y the NIST r eal-gas mo del b y en tering the f ollowing t ext command in the ANSY S Fluen t console: /define/user-defined/real-gas-models/nist-settings When pr ompt ed with User-defined refprop library and fluids files? answ er yes . The default names f or the r efpr op libr ary and the fluid file pa ths c orrespond t o the REFPR OP v9.1 files pr ovided with y our ANSY S Fluen t installa tion. You c an r evert to the older REFPR OP v7.0.1 database b y acc epting the default r efpr op libr ary pa th and en tering the f ollowing names a t the prompts f or libr ary name and fluid files pa th: Select refprop library path [" path\fluent19.5.0\realgas"] Select refprop library name[“librealgas”] “librealgas7” Select refprop fluid files path [" path\fluent19.5.0\realgas\lib"] “path\fluent19.5.0\realgas\lib7.0” wher e path is the ANSY S Fluen t installa tion dir ectory (for e xample ,C:\Program Files\ANSYS Inc\v195\fluent ). ANSY S Fluen t will op en REFPR OP v7.0 libr ary and r eport the inf ormation in the c onsole . To swit ch back t o the default REFPR OP v9.1 pr operty da tabase , enter the /define/user- defined/real-gas-models/nist-settings command again and en ter no at the pr ompt. ANSY S Fluen t will r eport the change in the c onsole windo w. 1183Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Real G as M odels8.16.4.4. Solution Str ategies and C onsider ations for NIST R eal G as Mo del S imulation The flo w mo deling of NIST r eal-gas flo w is much mor e comple x and challenging than simple ideal- gas flo w.Therefore, you should e xpect the solution t o converge a t much slo wer rate with r eal-gas flow than when r unning ideal-gas flo w. Also due t o the c omple xity of the equa tions used in pr operty evalua tions , converging a solution with the r eal-gas mo del is in gener al done a t much lo wer C ourant values when y ou ar e using the densit y-based solv er, or a t much lo wer under-r elaxa tion v alues if y ou are using the pr essur e-based solv er. It is r ecommended tha t you first a ttempt t o converge y our solution using first-or der discr etiza tion, then swit ch t o sec ond-or der discr etiza tions and r e-iterate to convergenc e. The r eal-gas pr operties in NIST ar e defined within a limit ed/b ounded r ange . It is imp ortant tha t the flow conditions y ou ar e pr escr ibing fall within the r ange of the da tabase . It is p ossible tha t you sp ecify flow at a sta te tha t is ph ysically v alid but other wise not defined in the da tabase . In this situa tion the solution will div erge or immedia tely gener ate an er ror message on the ANSY S Fluen t console as so on as the sta te crosses the limit of the da tabase . In some instanc es, the ac tual c onverged sta te is just within the b ounded defined da tabase but only tr ansit ory outside the r ange . In this situa tion the di- vergenc e can b e avoided b y lowering the C ourant value or under-r elaxa tion fac tors so a less aggr essiv e convergenc e rate is adapt ed. Finally , if y ou a ttempt t o initializ e the flo w fr om an inlet flo w conditions and an er ror message is gener ated fr om one of the pr operty routines , then this is an indic ator tha t the flo w conditions y ou have sp ecified is not defined within the r ange of the da tabase . 8.16.4.4.1. Writing Your C ase F ile When y ou sa ve your c omplet ed r eal gas mo del t o a c ase file , the link age t o the shar ed libr ary con- taining r eal gas pr operties will b e sa ved t o the c ase file (along with pr operty da ta for the ma terial you selec ted in the NIST r eal gas mo del). Consequen tly, whene ver y ou r ead y our c ase file in a la ter session, ANSY S Fluen t will load and r eport this inf ormation t o the c onsole dur ing the r ead pr ocess. 8.16.4.4.2. Postpr ocessing All postpr ocessing func tions pr operly report and displa y the cur rent ther modynamic and tr ansp ort properties of the selec ted r eal gas mo del. The ther modynamic and tr ansp ort properties c ontrolled by the NIST r eal gas mo del include the f ollowing: •densit y •enthalp y •entropy •molecular w eigh t •molecular visc osity •sound sp eed •specific hea t •ther mal c onduc tivit y In addition t o the pr operties list ed ab ove, you c an also r eport •compr essibilit y fac tor Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1184Physical Properties•any quan tities tha t are der ived fr om the pr operties list ed ab ove (for e xample , total quan tities , ratio of specific hea ts) 8.16.5. The U ser-D efined Real G as M odel The user-defined r eal gas mo del (UDR GM) has b een de velop ed t o allo w you t o wr ite your o wn cust om real gas mo del t o fit y our par ticular mo deling needs . It also allo ws you t o simula te a single-sp ecies flow, multiple-sp ecies mix ture flo w, multiphase flo w, or v olumetr ic reactions . The f ollowing limita tions e xist f or the UDR GM: 8.16.5.1. Limitations of the User -Defined R eal G as Mo del •You c annot include mor e than one user-defined r eal gas ma terial (fluid or mix ture) in the same pr oblem. However, you c an use other ma terials t ogether with r eal gas in y our simula tion. •When y ou ar e using the UDR GM, the ma terials defined in y our r eal gas UDF will app ear in the Create/Edit Materials D ialog Box (p.3386 ) with the name real-gas-fluid or real-gas-mix ture and all ph ysical and ther- modynamic pr operty inputs disabled . Use the Create/Edit M aterials D ialog Box (p.3386 ) to define or mo dify : –Mass diffusivit y pr operty in the r eal-gas-mix ture ma terial if y ou ar e mo deling multic omp onen t flo w. –Chemic al reactions in the r eal-gas-mix ture if y ou ar e mo deling r eacting flo w. –Radia tion pr operties f or the r eal-gas-mix ture or the r eal-gas-fluid ma terials if y ou ar e mo deling r adia tion. –Properties of ma terials other than the user-defined real-gas-mix ture or real-gas-fluid materials. Note If you ar e using the UDR GM t ogether with other ma terials fr om ANSY S Fluen t's pr operty database in disp ersed phase or multiphase c alcula tions , tak e care to use the same r efer- ence temp erature as in ANSY S Fluen t in y our r eal-gas UDF .The r eference temp erature in ANSY S Fluen t is 298.15 K. •Pressur e-inlets , mass flo w-inlets , and pr essur e-outlets ar e the only inflo w and outflo w boundar ies a vailable for use with the r eal gas mo dels . •Non-r eflec ting b oundar y conditions ar e not c ompa tible with the r eal gas mo dels when using the densit y- based solv er. If your mo del r equir es NRBC and a r eal gas mo del, you must use the pr essur e-based solv er. •The UDR GM c an b e used with the E uler ian multiphase mo dels . •The UDR GM is c ompa tible with the Lagr angian D ispersed P hase M odels . Refer to Using the C ubic E qua tion of State Models with the Lagr angian D ispersed P hase M odels (p.1171 ) for guidelines and r estrictions of this appr oach. •The r eal gas mo dels c annot b e used with the non-pr emix ed, par tially pr emix ed, and c omp osition PDF transp ort combustion mo dels . Chemic al reactions c an ho wever b e mo deled with the finit e rate and edd y dissipa tion mo dels . Note tha t the Dimension Reduc tion mo del is not a vailable with the r eal gas mo dels . 1185Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Real G as M odelsThe UDR GM r equir es a libr ary of func tions wr itten in the C pr ogramming language . Moreover, ther e are certain c oding r equir emen ts tha t need t o be followed when wr iting these func tions . Sample r eal gas func tion libr aries ar e pr ovided t o assist y ou in wr iting y our o wn UDR GM. When UDR GM func tions are compiled , the y will b e gr oup ed in a shar ed libr ary tha t later will b e loaded and link ed with the ANSY S Fluen t executable .The pr ocedur e for using the UDR GM is defined as f ollows: 1.Define the r eal gas equa tion of sta te and all r elated ther modynamic and tr ansp ort property equa tions . 2.Create a C sour ce code file tha t conforms t o the f ormat defined in this sec tion. 3.Start ANSY S Fluen t and set up y our c ase file in the usual w ay. 4.Compile y our UDR GM C libr ary and build a shar ed libr ary file (y ou c an use the a vailable c ompiled UDF utilities in either the gr aphic al user in terface or the t ext command in terface). 5.Load y our newly cr eated UDR GM libr ary via the t ext command menu: If a single-sp ecies UDR GM t o be used , then the t ext command menu is: > define/user-defined/real-gas-models/user-defined-real-gas-model use user defined real gas? [no] yes On the other hand , if y ou ar e simula ting multiple-sp ecies UDR GM flo w, then the t ext command menu t o use is: > define/user-defined/real-gas-models/user-defined-multispecies-real-gas-model use user multispecies defined real gas? [no] yes Upon ac tivating the UDR GM, the func tion libr ary will no w supply the fluid ma terial pr operties f or your c ase. 6.You c an simula te volumetr ic reactions with y our r eal gas mo del using the Species M odel D ialog Box (p.3294 ), or the t ext interface (define/models/species/volumetric-reactions? ). You c an acc ess the Species M odel from the tr ee b y going t o Setup /Models /Species and double- click ing Species . In the Species M odel D ialog Box (p.3294 ) •Enable Species Transp ort under Model. •Enable Volumetr ic under Reac tions . •Selec t the appr opriate Turbulenc e-Chemistr y In teraction option. •Set up the r eaction b y click ing the Edit... butt on f or the real-gas-mix tureMixture M aterial. Imp ortant Note tha t the fluid ma terials and their pr operties, app earing in the Create/Edit M a- terials D ialog Box (p.3386 ), are the ones defined in y our r eal gas UDF .You c annot modify the ma terials via this dialo g box, however, you c an set up the v olumetr ic re- Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1186Physical Propertiesaction. If you w ould lik e to mo dify the mix ture ma terials and their pr operties, this should b e done in the r eal gas UDF .The v olumetr ic reactions f or y our r eal gas mix ture are defined in the same w ay as f or an y ANSY S Fluen t mix ture. For details , refer to Defining R eactions (p.1634 ). Alternatively, the chemic al reactions c an b e set up using the define/models/species and define/materials text command . Imp ortant Note tha t the chemic al reactions should b e ac tivated af ter y our r eal gas UDF has b een built and loaded . It is also r ecommended t o test and v alida te your r eal gas UDF , running the c old flo w calcula tion pr ior t o attempting t o solv e the r eacting flo w. Also, mak e sur e that the applic abilit y range of the r eal gas func tions in y our UDF fully c overs the t em- perature and pr essur e range of the r eacting flo w calcula tion. 7.Run y our c alcula tion. When using the UDR GM the r obustness of the solv er and the sp eed of flo w convergenc e will lar gely dep end on the c omple xity of the ma terial pr operties y ou ha ve defined in y our UDF . It is imp ortant to understand the op erational r ange of the pr operty func tions y ou ar e coding so y ou c an simula te the flo w within tha t range . 8.16.5.2. Writing the UDR GM C F unc tion Libr ary Creating a UDR GM C func tion libr ary is r easonably str aigh tforward; however, your c ode must mak e use of sp ecific func tion names and macr os, which will b e descr ibed in detail b elow.The basic libr ary requir emen ts ar e as f ollows: •The c ode must c ontain the udf.h file inclusion dir ective at the b eginning of the sour ce code.This allo ws the definitions f or DEFINE macr os and other ANSY S Fluen t func tions t o be acc essible dur ing the c ompil- ation pr ocess. •The c ode must include a t least one of the UDF’ s DEFINE func tions (tha t is DEFINE_ON_DEMAND ) to be able t o use the c ompiled UDFs utilit y (see the sample UDR GM c odes pr ovided b elow). •Any values tha t are passed t o the solv er b y the UDR GM or r etur ned b y the solv er to the UDR GM ar e assumed to be in SI units . •You must use the pr incipal set of func tions list ed b elow in y our UDR GM libr ary.These func tions ar e the mechanism b y which y our ther modynamic pr operty da ta ar e transf erred t o the ANSY S Fluen t solv er. Note that ANYNAME can b e an y str ing of alphanumer ic char acters, and allo ws you t o pr ovide unique names t o your libr ary func tions . Function inputs fr om the ANSY S Fluen t solv er consist of one or mor e of the f ollowing v ariables: = Temp erature, K = P ressur e, Pa = D ensit y, kg/ 1187Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Real G as M odels[] = S pecies mass fr action cell = C ell or fac e inde x, dep ending on whether the thr ead is a c ell or fac e zone;NULL_CELL is passed when the func tion is c alled without a c ell/fac e context thread = P ointer to thr ead str ucture;NULL is passed when the func tion c alled without thr ead context Imp ortant • []: ANSY S Fluen t solv er retur ns a v alue of 1.0 for [] in single-sp ecies flo ws. For multiple- species flo ws, [] is a v ector ar ray containing sp ecies mass fr action in an or der defined b y the user setup func tion. •For temp erature, densit y, pressur e and sp ecies mass fr actions the UDR GM c ode should use the values pr ovided as func tions ar gumen ts.The c orresponding v alues in the solution ar rays, which are acc essible via c ell inde x and thr ead p ointer, may temp orarily diff er fr om these dep ending on algor ithmic details , and the func tion ar gumen ts tak e pr ecedenc e. The UDR GM func tion names and ar gumen t lists , followed b y a shor t descr iption of the func tion, are as follows: void ANYNAME_Setup(Domain *domain, cxboolean vapor_phase, char *species_list, int (*messagefunc)(const char *format,...), void (*errorfunc)(const char *format, ...)) performs mo del setup and initializa tion. Can b e used t o read da ta and par amet ers r elated t o your UDR GM. When wr iting UDFs f or multiple-sp ecies , use this func tion t o sp ecify the numb er of sp ecies and the name of the sp ecies as sho wn in the multiple-sp ecies e xample .The B oolean v ariable ,vapor_phase , passes to your UDF the setting of the t ext-interface command define/user-defined/real-gas-mod- els/set-state . The messagefunc argumen t is a func tion tha t you c an use f or including diagnostic output in the tr anscr ipt file , and the errorfunc argumen t is the equiv alen t of er ror reporting .The f ormat string and additional ar gumen ts follow the same syn tax as the printf C func tion. double ANYNAME_density(cell_t cell, Thread *thread, cxboolean vapor_phase, double T, double P, double yi[]) retur ns the v alue of densit y as a func tion of phase , temp erature, pressur e and sp ecies mass-fr action if applic able .The B oolean v ariable vapor_phase passes t o your UDF the setting of the t ext-interface command define/user-defined/real-gas-models/set-state , or, if applic able , the z one state set b y the t ext-interface command define/boundary-conditions/modify- zones/change-zone-state . Imp ortant Since this func tion is c alled numer ous times dur ing each solv er it eration, it is imp ortant to mak e this func tion as numer ically efficien t as p ossible . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1188Physical Propertiesdouble ANYNAME_specific_heat(cell_t cell, Thread *thread, double T, double Rho, double P, double yi[]) retur ns the r eal gas sp ecific hea t at constan t pressur e as a func tion of t emp erature, densit y, absolut e pressur e, and sp ecies mass-fr action if applic able . double ANYNAME_enthalpy(cell_t cell, Thread *thread, double T, double Rho, double P, double yi[]) retur ns the en thalp y as a func tion of t emp erature, densit y, absolut e pr essur e, and sp ecies mass-fr action if applic able . double ANYNAME_entropy(cell_t cell, Thread *thread, double T, double Rho, double P, double yi[]) retur ns the en tropy as a func tion of t emp erature, densit y, absolut e pr essur e, and sp ecies mass-fr action if applic able . double ANYNAME_mw(double yi[]) retur ns the fluid molecular w eigh t. double ANYNAME_speed_of_sound(cell_t cell, Thread *thread, double T, double Rho, double P, double yi[]) retur ns the v alue of sp eed of sound as a func tion of t emp erature, densit y, absolut e pr essur e, and sp ecies mass-fr action if applic able . double ANYNAME_viscosity(cell_t cell, Thread *thread, double T, double Rho, double P, double yi[]) retur ns the v alue of d ynamic visc osity as a func tion of t emp erature, densit y, absolut e pr essur e, and species mass-fr action if applic able . double ANYNAME_thermal_conductivity(cell_t cell, Thread *thread, double T, double Rho, double P, double yi[]) retur ns the v alue of ther mal c onduc tivit y as a func tion of t emp erature, densit y, absolut e pr essur e, and species mass-fr action if applic able . double ANYNAME_rho_t(cell_t cell, Thread *thread, double T, double Rho, double P, double yi[]) retur ns the v alue of at constan t pressur e as a func tion of t emp erature, densit y, absolut e pr essur e, and sp ecies mass-fr action if applic able . double ANYNAME_rho_p(cell_t cell, Thread *thread, double T, double Rho, double P, double yi[]) retur ns the v alue of at constan t temp erature as a func tion of t emp erature, densit y, absolut e pr essur e, and sp ecies mass-fr action if applic able . double ANYNAME_enthalpy_t(cell_t cell, Thread *thread, double T, double Rho, double P, double yi[]) retur ns the v alue of at constan t pressur e as a func tion of t emp erature, densit y, absolut e pr essur e, and sp ecies mass-fr action if applic able . Note tha t by definition , so this func tion should simply r etur n the sp ecific hea t value . 1189Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Real G as M odelsdouble ANYNAME_enthalpy_p(cell_t cell, Thread *thread, double T, double Rho, double P, double yi[]) retur ns the v alue of at constan t temp erature as a func tion of t emp erature, densit y, absolut e pr essur e, and sp ecies mass-fr action if applic able . double ANYNAME_enthalpy_prime (cell_t cell ,Thread *thread ,double T ,double Rho ,double P ,double yi[] ,double hi[] ) retur ns the v alue of the mix ture en thalp y as a func tion of t emp erature, densit y, absolut e pr essur e, and species mass fr action. In addition, your UDF must set the elemen ts of the double ar ray hi[] to the en- thalp y of each sp ecies , in the same or der as the y are referenced in the mass fr action ar ray yi[] . Note that the en thalp y in the func tion enthalpy_prime is defined as the sum of sensible en thalp y plus species f ormation en thalp y, and y ou should mak e sur e tha t its c omputa tion is c onsist ent with the sensible en thalp y func tion ANYNAME_enthalpy .The func tion ANYNAME_enthalpy_prime is requir ed for the c alcula tion of the hea t of r eactions , if chemic al reactions ar e being simula ted. If you ar e not solving r eacting flo ws, the func tion ANYNAME_enthalpy_prime can simply b e omitt ed. At the end of the c ode y ou must define a str ucture of t ype RGAS_Function whose memb ers ar e pointers t o the pr incipal func tions list ed ab ove.The str ucture is of t ype RGAS_Function and its name is RealGasFunctionList . Imp ortant It is imp erative tha t the sequenc e of func tion p ointers sho wn b elow b e followed. Other wise , your r eal gas mo del will not load pr operly in to the ANSY S Fluen t code. UDF_EXPORT RGAS_Functions RealGasFunctionList = { ANYNAME_Setup, /* Setup initialize */ ANYNAME_density, /* density */ ANYNAME_enthalpy, /* sensible enthalpy */ ANYNAME_entropy, /* entropy */ ANYNAME_specific_heat, /* specific_heat */ ANYNAME_mw, /* molecular_weight */ ANYNAME_speed_of_sound, /* speed_of_sound */ ANYNAME_viscosity, /* viscosity */ ANYNAME_thermal_conductivity, /* thermal_conductivity */ ANYNAME_rho_t, /* drho/dT |const p */ ANYNAME_rho_p, /* drho/dp |const T */ ANYNAME_enthalpy_t, /* dh/dT |const p */ ANYNAME_enthalpy_p /* dh/dp |const T */ ANYNAME_enthalpy_prime /* enthalpy */ }; If volumetr ic reactions ar e not b eing simula ted, then the func tion ANYNAME_enthalpy_prime can be remo ved or ignor ed fr om the RealGasFunctionList structure descr ibed her e. The pr incipal set of func tions descr ibed ar e the only func tions in the UDR GM tha t will b e in teracting directly with the ANSY S Fluen t code. In man y cases , your mo del ma y requir e fur ther func tions tha t will b e called fr om the pr incipal func tion set. For e xample , when multiple-sp ecies r eal gas mo del UDFs ar e wr itten, the pr incipal func tions will r etur n the mix ture ther modynamic pr operties based on some sp ecified mixing-la w.Therefore, you ma y want to add fur ther func tions tha t will r etur n the ther modynamic pr operties f or the individual sp ecies .These auxiliar y func tions will b e called fr om the principal set of func tions . See User-D efined R eal G as M odels (UDR GM) in the Fluen t Customiza tion Manual for e xamples tha t clear ly illustr ate this str ategy. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1190Physical Properties8.16.5.3. Compiling Your UDR GM C F unc tions and Building a Shar ed Libr ary File This sec tion pr esen ts the st eps y ou must f ollow to compile y our UDR GM C c ode and build a shar ed library file .This pr ocess r equir es the use of a C c ompiler . For mor e details on c ompiler r equir emen ts, see Compilers in the Fluent C ustomization Manual .To use the UDR GM y ou must first build the UDR GM library by compiling y our UDR GM C c ode and then load the libr ary into the ANSY S Fluen t code.The UDR GM shar ed libr ary is built in the same w ay tha t the ANSY S Fluen t executable itself is built. Internally , a scr ipt c alled Makefile is used t o in voke the sy stem C c ompiler t o build an objec t code libr ary that contains the na tive machine language tr ansla tion of y our higher-le vel C sour ce code.This shar ed library is then loaded in to ANSY S Fluen t (either a t run time or aut oma tically when a c ase file is r ead) by a pr ocess c alled dynamic loading .The objec t libr aries ar e sp ecific t o the c omput er ar chitecture being used , as w ell as t o the par ticular v ersion of the ANSY S Fluen t executable b eing r un.The libr aries must , ther efore, be rebuilt an y time ANSY S Fluen t is up graded , when the c omput er’s op erating sy stem level changes , or when the job is r un on a diff erent type of c omput er.The gener al pr ocedur e for compiling UDR GM C c ode is as f ollows: •Place the UDR GM C c ode in the f older , tha t is, wher e your c ase file r esides . •Launch ANSY S Fluen t. •Read y our c ase file in to ANSY S Fluen t. •You c an no w compile y our UDR GM C c ode and build a shar ed libr ary file using either the gr aphic al in terface or the t ext command in terface. Imp ortant To build UDR GM libr ary you will use the c ompiled UDF utilities . However, you will not use the UDF utilities t o load the libr ary. A separ ate loading ar ea for the UDR GM libr ary will b e used . 8.16.5.3.1. Compiling the UDR GM Using the Gr aphic al Int erface If the build is succ essful, then the c ompiled libr ary will b e plac ed in the appr opriate ar chitecture folder (f or e xample ,win64/2d) . By default the libr ary name is libudf.so (libudf.dll on Windo ws). More inf ormation on c ompiled UDFs and building libr aries using the ANSY S Fluen t graphic al user interface can b e found in the Fluen t Customiza tion M anual . 8.16.5.3.2. Compiling the UDR GM Using the Text Int erface The UDR GM libr ary can b e compiled in the t ext command in terface as f ollows: •Selec t the menu it em define → user-defined → compiled-functions . •Selec t the compile option. 1191Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Real G as M odels•Enter the c ompiled UDF libr ary name . Imp ortant The name giv en her e is the name of the f older wher e the shar ed libr ary (for e xample , libudf ) will r eside . For e xample , if y ou pr ess Enter then a f older should e xist with the name libudf , and this f older will c ontain a libr ary file c alled libudf . If, however, you t ype a new libr ary name such as myrealgas , then a f older c alled myrealgas will b e created and it will c ontain the libr ary libudf . •Continue on with the pr ocedur e when pr ompt ed. •Enter the C sour ce file names . Imp ortant Ideally y ou should plac e all of y our func tions in to a single file . However, you c an split them in to separ ate files if desir ed. •Enter the header file names , if applic able . If you do not ha ve an e xtra header file then pr ess Enter when prompt ed. ANSY S Fluen t will then star t compiling the UDR GM C c ode and put it in the appr opriate ar chitecture folder . Example: > define/user-defined/compiled-functions load OR compile ? [load] compile Compiled UDF library name: ["libudf"] my_lib Make sure that UDF source files are in the folder that contains your case and data files. If you have an existing libudf folder, please remove this folder to ensure that latest files are used. Continue?[yes] RETURN Give C-Source file names: First file name: [""] my_c_file.c RETURN Next file name: [""] RETURN Give header file names: First file name: [""] my_header_file.h RETURN 8.16.5.3.3. Loading the UDR GM Shar ed Libr ary File Load the UDR GM libr ary: •Go to the f ollowing menu it em in the t ext command in terface. define → user-defined → real-gas-models Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1192Physical Properties•Selec t one of the f ollowing –user-defined-real-gas-model if you ar e mo deling a single-sp ecies r eal gas fluid –user-defined-multispecies-real-gas-model if you ar e mo deling a multiple-sp ecies fluid- mixture •Turn on the r eal gas mo del. –For single-sp ecies: use user defined real gas? [no] yes –For multiple-sp ecies: use multispecies user defined real gas? [no] yes ANSY S Fluen t will ask f or the lo cation of the user-defined r eal gas libr ary.You c an en ter either the name of the f older wher e the UDR GM shar ed libr ary is c alled or the en tire pa th to the UDR GM shar ed libr ary. If the loading of the UDR GM libr ary is succ essful y ou will see a message similar t o the f ollowing: Opening user-defined realgas library "RealgasLibraryname"... Library "RealgasDirName/lnamd64/2d/libudf.so" opened Setting material "air" to a real-gas... Loading Real-RealGasPrefexLable Library: 8.16.5.4. UDR GM E xample: Ideal G as E quation of Stat e This sec tion descr ibes an e xample of a user-defined r eal gas mo del. You c an use this e xample as the basis f or y our o wn UDR GM c ode. In this simple e xample , the standar d ideal gas equa tion of sta te is used in the UDR GM. See User-D efined R eal G as M odels (UDR GM) in the Fluen t Customiza tion M anual for mor e examples of UDR GM func tions , including multi-sp ecies r eal gas and r eacting r eal-gas e xamples . = pr essur e = temp erature = sp ecific hea t = en thalp y = en tropy = densit y = sp eed of sound = univ ersal gas c onstan t/molecular w eigh t The ideal gas equa tion of sta te can b e wr itten in t erms of pr essur e and t emp erature as (8.119) The sp ecific hea t is defined t o be constan t = 1006.42. 1193Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Real G as M odelsThe en thalp y is, ther efore, defined as (8.120) and en tropy is giv en b y (8.121) wher e = 288.15 K and = 101325 P a The sp eed of sound is simply defined as (8.122) The densit y der ivatives ar e: (8.123) (8.124) The en thalp y der ivatives ar e: (8.125) (8.126) When y ou enable the r eal gas mo del and load the libr ary succ essfully in to ANSY S Fluen t, you will b e using the equa tion of sta te and other fluid pr operties fr om this libr ary rather than the one built in to the ANSY S Fluen t code. 8.16.5.4.1. Ideal G as UDR GM C ode Listing /**********************************************************************/ /* User Defined Real Gas Model : */ /* For Ideal Gas Equation of State */ /* */ /**********************************************************************/ #include "udf.h" #include "stdio.h" #include "ctype.h" #include "stdarg.h" #define MW 28.966 /* molec. wt. for single gas (Kg/Kmol) */ #define RGAS (UNIVERSAL_GAS_CONSTANT/MW) static int (*usersMessage)(const char *, ...); static void (*usersError)(const char *, ...); DEFINE_ON_DEMAND(I_do_nothing) { /* This is a dummy function to allow us to use */ /* the Compiled UDFs utility */ } void IDEAL_error(int err, char *f, char *msg) { Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1194Physical Properties if (err) usersError("IDEAL_error (%d) from function: %s\n%s\n", err, f, msg); } void IDEAL_Setup(Domain *domain, cxboolean vapor_phase, char *filename, int (*messagefunc)(const char *format, ...), void (*errorfunc)(const char *format, ...)) { /* Use this function for any initialization or model setups*/ usersMessage = messagefunc; usersError = errorfunc; usersMessage("\nLoading Real-Ideal Library: %s\n", filename); } double IDEAL_density(cell_t cell, Thread *thread, cxboolean vapor_phase, double Temp, double press, double yi[]) { double r = press / (RGAS * Temp); /* Density at Temp & press */ return r; /* (Kg/m^3) */ } double IDEAL_specific_heat(cell_t cell, Thread *thread, double Temp, double density, double P, double yi[]) { double cp = 1006.43; return cp; /* (J/Kg/K) */ } double IDEAL_enthalpy(cell_t cell, Thread *thread, double Temp, double density, double P, double yi[]) { double h = Temp * IDEAL_specific_heat(cell, thread, Temp, density, P, yi); return h; /* (J/Kg) */ } #define TDatum 288.15 #define PDatum 1.01325e5 double IDEAL_entropy(cell_t cell, Thread *thread, double Temp, double density, double P, double yi[]) { double s = IDEAL_specific_heat(cell, thread, Temp, density, P, yi) * log(fabs(Temp / TDatum)) + RGAS * log(fabs(PDatum / P)); return s; /* (J/Kg/K) */ } double IDEAL_mw(double yi[]) { return MW; /* (Kg/Kmol) */ } double IDEAL_speed_of_sound(cell_t cell, Thread *thread, double Temp, double density, double P, double yi[]) { double cp = IDEAL_specific_heat(cell, thread, Temp, density, P, yi); return sqrt(Temp * cp * RGAS / (cp - RGAS)); /* m/s */ } double IDEAL_viscosity(cell_t cell, Thread *thread, double Temp, double density, double P, double yi[]) { double mu = 1.7894e-05; return mu; /* (Kg/m/s) */ } double IDEAL_thermal_conductivity(cell_t cell, Thread *thread, double Temp, double density, double P, double yi[]) { double ktc = 0.0242; return ktc; /* W/m/K */ 1195Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Real G as M odels} double IDEAL_rho_t(cell_t cell, Thread *thread, double Temp, double density, double P, double yi[]) { /* derivative of rho wrt. Temp at constant p */ double rho_t = -density / Temp; return rho_t; /* (Kg/m^3/K) */ } double IDEAL_rho_p(cell_t cell, Thread *thread, double Temp, double density, double P, double yi[]) { /* derivative of rho wrt. pressure at constant T */ double rho_p = 1.0 / (RGAS * Temp); return rho_p; /* (Kg/m^3/Pa) */ } double IDEAL_enthalpy_t(cell_t cell, Thread *thread, double Temp, double density, double P, double yi[]) { /* derivative of enthalpy wrt. Temp at constant p */ return IDEAL_specific_heat(cell, thread, Temp, density, P, yi); } double IDEAL_enthalpy_p(cell_t cell, Thread *thread, double Temp, double density, double P, double yi[]) { /* derivative of enthalpy wrt. pressure at constant T */ /* general form dh/dp|T = (1/rho)*[ 1 + (T/rho)*drho/dT|p] */ /* but for ideal gas dh/dp = 0 */ return 0.0 ; } UDF_EXPORT RGAS_Functions RealGasFunctionList = { IDEAL_Setup, /* initialize */ IDEAL_density, /* density */ IDEAL_enthalpy, /* enthalpy */ IDEAL_entropy, /* entropy */ IDEAL_specific_heat, /* specific_heat */ IDEAL_mw, /* molecular_weight */ IDEAL_speed_of_sound, /* speed_of_sound */ IDEAL_viscosity, /* viscosity */ IDEAL_thermal_conductivity, /* thermal_conductivity */ IDEAL_rho_t, /* drho/dT |const p */ IDEAL_rho_p, /* drho/dp |const T */ IDEAL_enthalpy_t, /* dh/dT |const p */ IDEAL_enthalpy_p /* dh/dp |const T */ }; /**************************************************************/ 8.16.5.5. Additional UDR GM E xamples You c an find the f ollowing additional UDR GM e xamples in the Fluen t Customiza tion M anual : •The A ungier R edlich K wong equa tion of sta te for single c omp onen t flo w. See UDR GM Example: Redlich- Kwong E qua tion of S tate in the Fluen t Customiza tion M anual for details . •A simple e xample of a multi-sp ecies r eal-gas mo del. See UDR GM Example: Multiple-S pecies R eal G as Model in the Fluen t Customiza tion M anual for details . •A real gas mo del e xample with the A ungier R edlich K wong equa tion of sta te, ideal gas mixing r ules and volumetr ic reactions . See UDR GM Example: Real G as M odel with Volumetr ic Reactions in the Fluen t Cus- tomiza tion M anual for details . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1196Physical PropertiesChapt er 9: Modeling B asic F luid F low This chapt er descr ibes the basic ph ysical mo dels tha t ANSY S Fluen t provides f or fluid flo w and the commands f or defining and using them. Models f or flo ws in mo ving z ones (including sliding and d y- namic meshes) ar e explained in Modeling F lows with M oving R eference Frames (p.1227 ), mo dels f or turbulenc e ar e descr ibed in Modeling Turbulenc e (p.1375 ), and mo dels f or hea t transf er (including r adi- ation) ar e pr esen ted in Modeling H eat Transf er (p.1467 ). An overview of mo deling sp ecies tr ansp ort and reacting flo ws is pr ovided in Modeling S pecies Transp ort and F inite-Rate Chemistr y (p.1613 ), details ab out models f or sp ecies tr ansp ort and r eacting flo ws are descr ibed in Modeling S pecies Transp ort and F inite- Rate Chemistr y (p.1613 ) – Modeling a C omp osition PDF Transp ort Problem (p.1779 ), and mo dels f or p ol- lutan t formation ar e pr esen ted in Modeling P ollutan t Formation (p.1823 ).The discr ete phase mo del is descr ibed in Modeling D iscrete Phase (p.1911 ), gener al multiphase mo dels ar e descr ibed in Modeling Multiphase F lows (p.2091 ), and the melting and solidific ation mo del is descr ibed in Modeling S olidific ation and M elting (p.2321 ). For inf ormation on mo deling p orous media, porous jumps , and lump ed par amet er fans and r adia tors, see Cell Z one and B oundar y Conditions (p.835). The inf ormation in this chapt er is pr esen ted in the f ollowing sec tions: 9.1. User-D efined Sc alar (UDS) Transp ort Equa tions 9.2. Periodic F lows 9.3. Swirling and R otating F lows 9.4. Compr essible F lows 9.5. Inviscid F lows 9.1. User-D efined Sc alar (UDS) Transp ort Equa tions For additional inf ormation, see the f ollowing sec tions: 9.1.1. Introduction 9.1.2. UDS Theor y 9.1.3. Setting U p UDS E qua tions in ANSY S Fluen t 9.1.1. Introduc tion ANSY S Fluen t can solv e the tr ansp ort equa tion f or an arbitr ary, user-defined sc alar (UDS) in the same way tha t it solv es the tr ansp ort equa tion f or a sc alar such as sp ecies mass fr action. Extra sc alar tr ansp ort equa tions ma y be needed in c ertain t ypes of c ombustion applic ations or f or e xample in plasma-en- hanc ed sur face reaction mo deling . ANSY S Fluen t allo ws you t o define additional sc alar tr ansp ort equa tions in y our mo del in the User-D efined Sc alars D ialog Box (p.3953 ). 9.1.2. UDS Theor y UDS theor y is descr ibed in the f ollowing sec tions: 9.1.2.1. Single P hase F low 9.1.2.2. Multiphase F low 1197Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.9.1.2.1. Single P hase F low For an arbitr ary sc alar , ANSY S Fluen t solv es the equa tion (9.1) wher e and are the diffusion c oefficien t and sour ce term supplied b y you f or each of the scalar equa tions . Note tha t is defined as a t ensor in the c ase of anisotr opic diffusivit y.The diffusion term is ther efore For isotr opic diffusivit y, could b e wr itten as wher e I is the iden tity ma trix. For the st eady-sta te case, ANSY S Fluen t will solv e one of the thr ee f ollowing equa tions , dep ending on the metho d used t o comput e the c onvective flux: •If convective flux is not to be comput ed, ANSY S Fluen t will solv e the equa tion (9.2) wher e and are the diffusion c oefficien t and sour ce term supplied b y you f or each of the scalar equa tions . •If convective flux is t o be comput ed with mass flo w rate, ANSY S Fluen t will solv e the equa tion (9.3) •It is also p ossible t o sp ecify a user-defined func tion t o be used in the c omputa tion of c onvective flux. In this c ase, the user-defined mass flux is assumed t o be of the f orm (9.4) wher e is the fac e vector ar ea. Imp ortant User-defined sc alars in solid z ones do not tak e in to acc oun t the c onvective term with moving r eference frames . 9.1.2.2. Multiphase F low For multiphase flo ws, ANSY S Fluen t solv es tr ansp ort equa tions f or two types of sc alars: per phase and mix ture. For an arbitr ary scalar in phase-l , denot ed b y , ANSY S Fluen t solv es the tr ansp ort equa tion inside the v olume o ccupied b y phase-l (9.5) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1198Modeling B asic F luid F lowwher e , , and are the v olume fr action, physical densit y, and v elocity of phase-l , respectively. and are the diffusion c oefficien t and sour ce term, respectively, which y ou will need t o sp ecify . In this c ase, scalar is asso ciated only with one phase ( phase-l ) and is c onsider ed an individual field variable of phase-l . The mass flux f or phase-l is defined as (9.6) If the tr ansp ort variable descr ibed b y sc alar represen ts the ph ysical field tha t is shar ed b etween phases , or is c onsider ed the same f or each phase , then y ou should c onsider this sc alar as b eing asso- ciated with a mix ture of phases , . In this c ase, the gener ic tr ansp ort equa tion f or the sc alar is (9.7) wher e mix ture densit y , mix ture velocity , and mix ture diffusivit y for the sc alar are calcula ted according t o (9.8) (9.9) (9.10) (9.11) (9.12) To calcula te mix ture diffusivit y, you must sp ecify individual diffusivities f or each ma terial asso ciated with individual phases . Note tha t if the user-defined mass flux option is ac tivated, then mass flux es sho wn in Equa- tion 9.6 (p.1199 ) and Equa tion 9.10 (p.1199 ) must b e replac ed in the c orresponding sc alar tr ansp ort equa tions . For mor e inf ormation ab out the theor etical back ground of user-defined sc alar tr ansp ort equa tions , see User-D efined Sc alar (UDS) Transp ort Equa tions in the Theor y Guide . 9.1.3. Setting U p UDS E qua tions in ANSY S Fluen t ANSY S Fluen t allo ws you t o define up t o user-defined sc alar (UDS) tr ansp ort equa tions in y our model. The gener al sc alar tr ansp ort equa tion, Equa tion 1.8 in the Theor y Guide , is sho wn b elow with the f our t erms (tr ansien t, flux, diffusivit y, sour ce) tha t you c an cust omiz e. (Equa tion 9.13 (p.1199 )).You will define a UDS tr ansp ort equa tion b y setting the par amet ers f or these f our t erms. (9.13) 1199Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User-D efined Sc alar (UDS) Transp ort Equa tionsIn addition, you c an set b oundar y conditions f or the v ariables within c ells of a fluid or solid z one f or a par ticular sc alar equa tion. This is done b y fixing the v alue of in Equa tion 9.13 (p.1199 ).When is fix ed in a giv en c ell, the UDS sc alar tr ansp ort is not solv ed and the c ell is not included when the residual sum is c omput ed. Additionally , you c an also sp ecify cust om b oundar y conditions in the mix ture on all w all, inflo w, and outflo w b oundar ies on a p er-sc alar basis . The pr ocedur es for setting up a user-defined sc alar (UDS) equa tion f or single-phase and multiphase flows are outlined b elow. Note tha t a signific ant diff erence between a UDS f or a single-phase v ersus a multiphase applic ation is tha t you must asso ciate each UDS with its c orresponding phase domain or mix ture domain, dep ending on y our applic ation. If you supply UDFs f or tr ansien t terms, convective fluxes, and sour ces, you must b e aware tha t the y are dir ectly c alled fr om the phase or mix ture domains , according t o the sc alar asso ciation settings . When setting up a UDS, ensur e tha t the sc alar tr ansp ort problem is w ell defined with pr oper D irich- let/N eumann b oundar y conditions . Depending on the na ture of the pr oblem, the UDS equa tion ma y need t o converge fur ther than the default c onvergenc e cr iterion of 0.1. Set the c onvergenc e cr iterion according t o your needs . In some instanc es, the r esiduals ma y not r eflec t the qualit y of the solution. In these c ases y ou should create monit ors on the UDS and use these monit ors t o judge solution c onvergenc e.There ar e se veral controls tha t you c an adjust t o impr ove convergenc e, however some of these adjustmen ts can incr ease the c omputa tion time .The f ollowing c ontrols c an help with c onvergenc e: •Using a fix ed c ycle, such as F-Cycle in plac e of Flexible cycle in the Advanc ed S olution C ontrols dialo g box. •Using an additional stabiliz er such as the B iconjuga te gr adien t stabiliza tion metho d. •Using an IL U smo other . •Increasing the pr e- and p ost-sw eeps a vailable in the Advanc ed S olution C ontrols dialo g box. •Adjusting the under r elaxa tion fac tors. See the Fluen t Customiza tion M anual for inf ormation on using UDFs t o define sc alar quan tities . 9.1.3.1. Single P hase F low 1.Specify the numb er of UDS equa tions y ou r equir e in the User-D efined Sc alars D ialog Box (p.3953 ) (Fig- ure 9.1: The U ser-D efined Sc alars D ialog Box (p.1201 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1200Modeling B asic F luid F lowParamet ers & C ustomiza tion → User D efined Sc alars New... Imp ortant The maximum numb er of user-defined sc alar tr ansp ort equa tions y ou c an define is 50. ANSY S Fluen t assigns numb ers t o the equa tions star ting with . Imp ortant Note tha t ANSY S Fluen t assigns a default name f or each sc alar equa tion (User Scalar 0 ,User Scalar 1 , and so on). These lab els will app ear in gr aphics dialo g boxes in ANSY S Fluen t.You c an change them b y means of a UDF . See the Fluen t Cus- tomiza tion M anual for details . Figur e 9.1: The U ser-D efined Sc alars D ialo g Box 2.Enable Inlet D iffusion if you w ant to include the diffusion t erm in the UDS tr ansp ort equa tion f or all inflo w and outflo w boundar ies. 3.Set the first user-defined sc alar equa tion par amet ers b y mak ing sur e tha t the UDS Inde x is set t o . a.Specify the Solution Z ones you w ant the sc alar equa tion t o be solv ed in as all fluid z ones ,all solid zones ,all z ones (fluid and solid) or selec ted z ones . If you cho ose selec ted z ones , click the Edit butt on t o view the list of z ones y ou c an selec t. b.Specify the Flux F unc tion to be none ,mass flo w rate, or a user-defined func tion (UDF). The Flux Func tion det ermines ho w the c onvective flux is c omput ed, which det ermines the equa tion tha t ANSY S Fluen t solv es for the user-defined sc alar. Selec ting none ,mass flo w rate, or a user-defined func tion r esults in ANSY S Fluen t solving Equa tion 1.9 ,Equa tion 1.10 , or Equa tion 1.11 , respectively (in the Theor y Guide ). See the Fluen t Customiza tion M anual for details on flux UDFs . 1201Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User-D efined Sc alar (UDS) Transp ort Equa tionsc.Specify the Unstead y Func tion to be none ,default , or a user-defined func tion (UDF). Selec t none for a st eady sta te solution and default if you w ant the tr ansien t term in Equa tion 1.8 in the Theor y Guide ). See the separ ate Fluen t Customiza tion M anual for details on unst eady UDFs . d.Repeat this pr ocess f or each sc alar equa tion b y incr emen ting the UDS Inde x. e.Click OK when all user sc alar equa tions ha ve been defined . 4.To sp ecify sour ce term(s) f or each of the UDS equa tions , enable the Sour ce Terms option in the Fluid or Solid dialo g box (Figur e 9.2: The F luid D ialog Box with Inputs f or S ource Terms f or a U ser-D efined Scalar (p.1202 )) and click the Sour ce Terms tab .The sour ce par amet ers will b e displa yed. Setup → Cell Z one C onditions Figur e 9.2: The F luid D ialo g Box with Inputs f or S our ce Terms f or a U ser-D efined Sc alar a.Specify the numb er of sour ces y ou r equir e for each sc alar equa tion b y click ing on the Edit... butt on next to the sc alar name (f or e xample ,User Sc alar 0 ).This will op en the User Sc alar 0 sour ces dialo g box (Figur e 9.3: The U ser Sc alar S ources D ialog Box (p.1203 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1202Modeling B asic F luid F lowFigur e 9.3: The U ser Sc alar S our ces D ialo g Box b.Specify the Numb er of U ser Sc alar S our ces for the sc alar equa tion b y incr emen ting the c oun ter. Based on the v alue y ou ha ve chosen, the sour ces will b e added t o the list in the dialo g box. Specify each sour ce to be none ,constan t, or a user-defined func tion (UDF). For details on defining a UDF scalar sour ce, see the Fluen t Customiza tion M anual . Click OK when y ou ha ve sp ecified all sc alar sour ces. 5.To sp ecify diffusivit y for each of the UDS equa tions , displa y the Materials Task P age (p.3384 ) (Fig- ure 9.4: The M aterials D ialog Box with Input f or D iffusivit y for UDS E qua tions (p.1204 )) and selec t either defined-p er-uds (the default) or user-defined in the dr op-do wn list f or UDS D iffusivit y. Setup → Materials → Create/Edit 1203Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User-D efined Sc alar (UDS) Transp ort Equa tionsFigur e 9.4: The M aterials D ialo g Box with Input f or D iffusivit y for UDS E qua tions See User-D efined Sc alar (UDS) D iffusivit y (p.1129 ) for details on the diff erent options a vailable t o you f or defining diffusion c oefficien ts. 6.To sp ecify b oundar y conditions f or the user-defined sc alars on w all, inflo w, and outflo w boundar ies, you can define a sp ecific v alue or a sp ecific flux f or each sc alar. A coupled b oundar y condition c an b e sp ecified on t wo-sided w alls f or sc alars tha t are to be solv ed in r egions on b oth sides of the w all (tha t is, scalars solv ed in b oth fluid and solid zones). Setup → Boundar y Conditions a.In the UDS tab under User D efined Sc alar B oundar y Condition , selec t either Specified F lux or Specified Value in the dr op-do wn list ne xt to each sc alar (f or e xample ,User Sc alar 0 ) for a b oundar y wall. For in terior w alls, selec t Coupled B oundar y if the sc alars ar e to be solv ed on b oth sides of a two-sided w all. Note tha t the Coupled B oundar y option will only sho w up in the dr op-do wn list if the sc alar is defined in the fluid and solid zones in the User-D efined Sc alars D ialog Box (p.3953 ). b.Under User D efined Sc alar B oundar y Value , enter a c onstan t value or selec t a user-defined func tion from the dr op-do wn list f or each sc alar. If you selec t Specified F lux, your input will b e the v alue of the flux a t the b oundar y (tha t is, the nega tive of the t erm in par enthesis on the lef t-hand side of in the Theor y Guide ) dot [as in the dot pr oduc t of] [as in the v ector, n], wher e is the nor mal in to the domain). If you selec t Specified Value , your input will b e the v alue of the sc alar itself a t the b oundar y. See the Fluen t Customiza tion M anual for inf ormation on using UDFs f or UDS b oundar y conditions . 7.Set the solution par amet ers in the Solution C ontrols task page , specify an initial v alue f or each UDS (as you do f or all other sc alar tr ansp ort equa tions), and c alcula te a solution. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1204Modeling B asic F luid F low8.Examine the r esults using the usual p ostpr ocessing t ools. In each p ostpr ocessing dialo g box, the list of field v ariables will include the User D efined Sc alars ... categor y, which c ontains the v alue of each UDS and its diffusion c oefficien t ( in Equa tion 1.8 ,Equa tion 1.9 ,Equa tion 1.10 , or Equa tion 1.11 (in the Theor y Guide ): •User Sc alar-n •Diffusion C oef. of Sc alar-n 9.1.3.2. Multiphase F low 1.Specify the numb er of sc alars in the User-D efined Sc alars D ialog Box (p.3953 ) (Figur e 9.5: The U ser-D efined Scalars D ialog Box for a M ultiphase F low (p.1205 )). Paramet ers & C ustomiza tion → User D efined Sc alars New... Figur e 9.5: The U ser-D efined Sc alars D ialo g Box for a M ultiphase F low Imp ortant The maximum numb er of user-defined sc alar tr ansp ort equa tions y ou c an define is 50. ANSY S Fluen t assigns numb ers t o the equa tions star ting with .The default asso ciation type is set t o mixture for all sc alars . Imp ortant Note tha t ANSY S Fluen t assigns a default name f or each sc alar equa tion (User Scalar 0 ,User Scalar 1 , and so on). These lab els will app ear in gr aphics dialo g boxes in ANSY S Fluen t.You c an change them b y means of a UDF . See the Fluen t Cus- tomiza tion M anual for details . 1205Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User-D efined Sc alar (UDS) Transp ort Equa tions2.Keep the default Inlet D iffusion enabled if y ou w ant to include the diffusion t erm in the UDS tr ansp ort equa tion f or all inflo w and outflo w boundar ies. 3.Set the first user-defined sc alar equa tion par amet ers b y mak ing sur e tha t the UDS Inde x is set t o . a.Selec t the Phase you w ant the sc alar equa tion solv ed in as a pr imar y phase , sec ondar y phase , or the mixture. b.Specify the Solution Z ones you w ant the sc alar equa tion t o be solv ed in as all fluid z ones ,all solid zones ,all z ones (fluid and solid) or selec ted z ones . If you cho ose selec ted z ones , click the Edit butt on t o view the list of z ones y ou c an selec t. c.Specify the Flux F unc tion to Unstead y Func tion the same w ay as y ou w ould f or a single phase flo w (see ab ove). d.Repeat this pr ocess f or each sc alar equa tion b y incr emen ting the UDS Inde x. e.Click OK when all user sc alar equa tions ha ve been defined . 4.Specify sour ce term(s) f or each of the UDS equa tions in the Fluid or Solid dialo g box as descr ibed f or a single phase flo w (see ab ove). 5.Specify b oundar y conditions f or the user-defined sc alars in the mix ture on all w all, inflo w, and outflo w boundar y as descr ibed f or a single phase flo w (see ab ove). 6.Set the solution par amet ers, specify an initial v alue f or each UDS (as y ou do f or all other sc alar tr ansp ort equa tions), and c alcula te a solution. 9.2. Periodic F lows Periodic flo w o ccurs when the ph ysical geometr y of in terest and the e xpected pa ttern of the flo w/ther mal solution ha ve a p eriodically r epeating na ture.Two types of p eriodic flo w can b e mo deled in ANSY S Fluen t. In the first t ype, no pr essur e dr op o ccurs acr oss the p eriodic planes . In the sec ond t ype, a pr essur e drop o ccurs acr oss tr ansla tionally p eriodic b oundar ies, resulting in “fully-de velop ed” or “streamwise- periodic” flow. This sec tion discusses str eamwise-p eriodic flo w. A descr iption of no-pr essur e-dr op p eriodic flo w is provided in Periodic B oundar y Conditions (p.999), and a descr iption of str eamwise-p eriodic hea t transf er is pr ovided in Modeling P eriodic H eat Transf er (p.1567 ). Information ab out str eamwise-p eriodic flo w is pr esen ted in the f ollowing sec tions: 9.2.1. Overview and Limita tions 9.2.2. User Inputs f or the P ressur e-Based S olver 9.2.3. User Inputs f or the D ensit y-Based S olvers 9.2.4. Monit oring the Value of the P ressur e Gradien t 9.2.5. Postpr ocessing f or Streamwise-P eriodic F lows For mor e inf ormation ab out the theor etical back ground of p eriodic flo ws, see Periodic F lows in the Theor y Guide . 9.2.1. Overview and Limita tions More inf ormation ab out p eriodic flo ws is pr esen ted in the f ollowing sec tions: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1206Modeling B asic F luid F low9.2.1.1. Overview 9.2.1.2. Limita tions f or M odeling S treamwise-P eriodic F low 9.2.1.1. Overview ANSY S Fluen t provides the abilit y to calcula te str eamwise-p eriodic—or “fully-de velop ed”—fluid flo w. These flo ws are enc oun tered in a v ariety of applic ations , including flo ws in c ompac t hea t exchanger channels and flo ws acr oss tub e banks . In such flo w configur ations , the geometr y varies in a r epeating manner along the dir ection of the flo w, leading t o a p eriodic fully-de velop ed flo w regime in which the flo w pa ttern repeats in succ essiv e cycles . Other e xamples of str eamwise-p eriodic flo ws include fully-de velop ed flo w in pip es and duc ts.These p eriodic c onditions ar e achie ved af ter a sufficien t en- trance length, which dep ends on the flo w Reynolds numb er and geometr ic configur ation. Streamwise-p eriodic flo w conditions e xist when the flo w pa ttern repeats over some length , with a constan t pressur e dr op acr oss each r epeating mo dule along the str eamwise dir ection. Figur e 9.6: Ex- ample of P eriodic F low in a 2D H eat Exchanger G eometr y (p.1207 ) depic ts one e xample of a p eriodically repeating flo w of this t ype tha t has b een mo deled b y including a single r epresen tative mo dule . Figur e 9.6: Example of P eriodic F low in a 2D H eat Exchanger G eometr y 9.2.1.2. Limitations for Mo deling Str eamwise-P erio dic F low The f ollowing limita tions apply t o mo deling str eamwise-p eriodic flo w: •The flo w must b e inc ompr essible . •When p erforming unst eady-sta te simula tions with tr ansla tional p eriodic b oundar y conditions , the sp ecified pressur e gr adien t is r ecommended . •If one of the densit y-based solv ers is used , you c an sp ecify only the pr essur e jump; for the pr essur e-based solv er, you c an sp ecify either the pr essur e jump or the mass flo w rate. 1207Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Periodic F lows•No net mass addition thr ough inlets/e xits or e xtra sour ce terms is allo wed. •Species c an b e mo deled only if inlets/e xits (without net mass addition) ar e included in the pr oblem. Re- acting flo ws are not p ermitt ed. •When y ou sp ecify a p eriodic mass-flo w rate, Fluen t will assume tha t the en tire flo w rate passes through one p eriodic c ontinuous fac e zone only . •Steady par ticle tr acks c an b e mo deled only if the par ticles ha ve a p ossibilit y to lea ve the domain without gener ating inc omplet e trajec tories. •While multiphase flo w can b e mo deled with tr ansla tional p eriodic b oundar y conditions , you c annot use the mass flo w rate sp ecific ation metho d. However, you c an sp ecify a c onstan t pressur e gr adien t. For p eriodic simula tions tha t include hea t transf er, see also the limita tions descr ibed in Constr aints for P eriodic H eat Transf er P redic tions (p.1567 ). 9.2.2. User Inputs f or the P ressur e-Based S olver If you ar e using the pr essur e-based solv er, in or der t o calcula te a spa tially p eriodic flo w field with a specified mass flo w rate or pr essur e der ivative, you must first cr eate a mesh with tr ansla tionally p eri- odic b oundar ies tha t are par allel t o each other and equal in siz e.You c an sp ecify tr ansla tional p eriodicit y in the Periodic C onditions D ialog Box (p.3564 ), as descr ibed in Periodic B oundar y Conditions (p.999). (If you need t o cr eate periodic b oundar ies, see Creating P eriodic Z ones and In terfaces (p.811)). In the Periodic C onditions D ialog Box (p.3564 ) tha t is op ened fr om the Boundar y Conditions Task Page (p.3479 ), you will c omplet e the f ollowing inputs af ter the mesh has b een r ead in to ANSY S Fluen t (Figur e 9.7: The P eriodic C onditions D ialog Box (p.1208 )): Setup → Boundar y Conditions → Periodic C onditions ... Figur e 9.7: The P eriodic C onditions D ialo g Box Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1208Modeling B asic F luid F low1.Selec t either the sp ecified mass flo w rate (Specify M ass F low) option or the sp ecified pr essur e gr adien t (Specify P ressur e Gradien t) option. For most pr oblems , the mass flo w rate acr oss the p eriodic b oundar y will b e a k nown quan tity; for others , the mass flo w rate will b e unk nown, but the pr essur e gr adien t ( in Equa tion 1.22 , in the Theor y Guide ) will b e a k nown quan tity. 2.Specify the mass flo w rate and/or the pr essur e gr adien t ( in Equa tion 1.22 , in the Theor y Guide ): •If you selec ted the Specify M ass F low option, enter the desir ed v alue f or the Mass F low R ate.You c an also sp ecify an initial guess f or the Pressur e Gradien t, but this is not r equir ed. Imp ortant For axisymmetr ic pr oblems , the mass flo w rate is p er radians . •If you selec ted the Specify P ressur e Gradien t option, enter the desir ed v alue f or Pressur e Gradien t. 3.Define the flo w dir ection b y setting the X,Y,Z (or X,Y in 2D) p oint under Flow D irection .The flo w will move in the dir ection of the v ector p ointing fr om the or igin t o the sp ecified p oint.The dir ection v ector must b e par allel t o the p eriodic tr ansla tion dir ection or its opp osite. 4.If you chose in st ep 1 t o sp ecify the mass flo w rate, set the par amet ers used f or the c alcula tion of .These paramet ers ar e descr ibed in detail b elow. After completing these inputs , you c an solv e the p eriodic v elocity field t o convergenc e. 9.2.2.1. Setting P aramet ers for the C alculation of β If you cho ose t o sp ecify the mass flo w rate, ANSY S Fluen t must c alcula te the appr opriate value of the pressur e gr adien t .You c an c ontrol this c alcula tion b y sp ecifying the Relaxa tion F actor and the Numb er of I terations , and b y supplying an initial guess f or . All of these inputs ar e en tered in the Periodic C onditions D ialog Box (p.3564 ). The Numb er of I terations sets the numb er of sub-it erations p erformed on the c orrection of in the pressur e correction equa tion. Because the v alue of is not k nown a pr iori, it must b e iterated on until the Mass F low R ate tha t you ha ve defined is achie ved in the c omputa tional mo del. This c orrection of occurs in the pr essur e correction st ep of the SIMPLE , SIMPLEC, or PISO algor ithm. A c orrection to the cur rent value of is c alcula ted based on the diff erence between the desir ed mass flo w rate and the ac tual one .The sub-it erations r eferred t o her e ar e performed within the pr essur e correction step t o impr ove the c orrection f or before the pr essur e correction equa tion is solv ed f or the r esulting pressur e (and v elocity) correction v alues .The default v alue of 2 sub-it erations should suffic e in most problems , but c an b e incr eased t o help sp eed c onvergenc e.The Relaxa tion F actor is an under-r elax- ation fac tor tha t controls c onvergenc e of this it eration pr ocess. You c an also sp eed up c onvergenc e of the p eriodic c alcula tion b y supplying an initial guess f or in the Pressur e Gradien t field . Note tha t the cur rent value of will b e displa yed in this field if y ou have performed an y calcula tions .To up date the Pressur e Gradien t field with the cur rent value a t any time , click the Update butt on. 1209Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Periodic F lows9.2.3. User Inputs f or the D ensit y-Based S olvers If you ar e using one of the densit y-based solv ers, in or der t o calcula te a spa tially p eriodic flo w field with a sp ecified pr essur e jump , you must first cr eate a mesh with tr ansla tionally p eriodic b oundar ies that are par allel t o each other and equal in siz e. (If you need t o cr eate periodic b oundar ies, see Creating Periodic Z ones and In terfaces (p.811).) Then, follow the st eps b elow: 1.In the Periodic D ialog Box (p.3517 ) (Figur e 9.8: The P eriodic D ialog Box (p.1210 )), which is op ened fr om the Boundar y Conditions task page , indic ate tha t the p eriodicit y is Transla tional (the default). Setup → Boundar y Conditions → Periodic → Edit... Figur e 9.8: The P eriodic D ialo g Box 2.Also in the Periodic D ialog Box (p.3517 ), set the Periodic P ressur e Jump ( in Equa tion 1.21 in the Theor y Guide ). After completing these inputs , you c an solv e the p eriodic v elocity field t o convergenc e. 9.2.4. Monit oring the Value of the P ressur e Gradien t If you ha ve sp ecified the mass flo w rate, you c an monit or the v alue of the pr essur e gr adien t dur ing the c alcula tion b y creating a r eport plot tha t includes p eriodic pr essur e gr adien t, to ensur e tha t you reach a c onverged solution. See Monit oring S tatistics (p.2655 ) for additional inf ormation. 9.2.5. Postpr ocessing f or S treamwise-P eriodic F lows For str eamwise-p eriodic flo ws, the v elocity field should b e complet ely p eriodic. If a densit y-based solv er is used t o comput e the p eriodic flo w, the pr essur e field r eported will b e the ac tual pr essur e (which is not p eriodic). If the pr essur e-based solv er is used , the pr essur e field r eported will b e the periodic pr essur e field of Equa tion 1.22 , in the Theor y Guide .Figur e 9.9: Periodic P ressur e Field Predic ted f or F low in a 2D H eat Exchanger G eometr y (p.1211 ) displa ys the p eriodic pr essur e field in the geometr y of Figur e 9.6: Example of P eriodic F low in a 2D H eat Exchanger G eometr y (p.1207 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1210Modeling B asic F luid F lowIf you sp ecified a mass flo w rate and had ANSY S Fluen t calcula te the pr essur e gr adien t, you c an check the pr essur e gr adien t in the str eamwise dir ection ( ) by looking a t the cur rent value f or Pressur e Gradien t in the Periodic C onditions D ialog Box (p.3564 ). Figur e 9.9: Periodic P ressur e Field P redic ted f or F low in a 2D H eat Exchanger G eometr y 9.3. Swirling and Rota ting F lows Many imp ortant engineer ing flo ws involve swir l or r otation and ANSY S Fluen t is w ell-equipp ed t o model such flo ws. Swirling flo ws are common in c ombustion, with swir l introduced in bur ners and combust ors in or der t o incr ease r esidenc e time and stabiliz e the flo w pa ttern. Rotating flo ws are also encoun tered in turb omachiner y, mixing tanks , and a v ariety of other applic ations . Information ab out r otating and swir ling flo ws is pr ovided in the f ollowing subsec tions: 9.3.1. Overview of S wirling and R otating F lows 9.3.2. Turbulenc e Modeling in S wirling F lows 9.3.3. Mesh S etup f or Swirling and R otating F lows 9.3.4. Modeling A xisymmetr ic Flows with S wirl or R otation For mor e inf ormation ab out the theor etical back ground of swir ling and r otating flo ws, see Swirling and Rotating F lows in the Theor y Guide . When y ou b egin the analy sis of a r otating or swir ling flo w, it is essen tial tha t you classify y our pr oblem into one of the f ollowing fiv e categor ies of flo w: •axisymmetr ic flo ws with swir l or r otation •fully thr ee-dimensional swir ling or r otating flo ws •flows requir ing a mo ving r eference frame 1211Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Swirling and R otating F lows•flows requir ing multiple mo ving r eference frames or mixing planes •flows requir ing sliding meshes Modeling and solution pr ocedur es for the first t wo categor ies ar e pr esen ted in this sec tion. The r emaining three, which all in volve “moving z ones ”, are discussed in Modeling F lows with M oving R eference Frames (p.1227 ). 9.3.1. Overview of S wirling and Rota ting F lows An overview of swir ling and r otating flo ws is pr esen ted in the f ollowing sec tions: 9.3.1.1. Axisymmetr ic Flows with S wirl or R otation 9.3.1.2. Three-D imensional S wirling F lows 9.3.1.3. Flows Requir ing a M oving R eference Frame 9.3.1.1. Axisymmetric F lows with S wirl or R otation Your pr oblem ma y be axisymmetr ic with r espect to geometr y and flo w conditions but still include swir l or r otation. In this c ase, you c an mo del the flo w in 2D (tha t is, solv e the axisymmetr ic pr oblem) and include the pr edic tion of the cir cumf erential (or swir l) velocity. It is imp ortant to not e tha t while the assumption of axisymmetr y implies tha t ther e ar e no cir cumf erential gr adien ts in the flo w, ther e may still b e nonz ero swir l velocities . 9.3.1.1.1. Momentum C onser vation E quation for S wirl Velocity The tangen tial momen tum equa tion f or 2D swir ling flo ws ma y be wr itten as (9.14) wher e is the axial c oordina te, is the r adial c oordina te, is the axial v elocity, is the r adial v elocity, and is the swir l velocity. 9.3.1.2. Three-D imensional S wirling F lows When ther e ar e geometr ic changes and/or flo w gr adien ts in the cir cumf erential dir ection, your swir ling flow pr edic tion r equir es a thr ee-dimensional mo del. If you ar e planning a 3D ANSY S Fluen t mo del that includes swir l or r otation, you should b e aware of the setup c onstr aints list ed in Coordina te System R estrictions (p.1213 ). In addition, you migh t consider simplific ations t o the pr oblem tha t migh t reduc e it t o an equiv alen t axisymmetr ic pr oblem, esp ecially f or y our initial mo deling eff ort. Because of the c omple xity of swir ling flo ws, an initial 2D stud y, in which y ou c an quick ly det ermine the eff ects of v arious mo deling and design choic es, can b e very beneficial. Imp ortant For 3D pr oblems in volving swir l or r otation, ther e ar e no sp ecial inputs r equir ed dur ing the pr oblem setup and no sp ecial solution pr ocedur es. Note, however, tha t you ma y want to use the c ylindr ical coordina te sy stem f or defining v elocity-inlet b oundar y condition inputs , as descr ibed in Defining the Velocity (p.930). Also, you ma y find the gr adual incr ease of the r otational sp eed (set as a w all or inlet b oundar y condition) helpful dur ing the solution Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1212Modeling B asic F luid F lowprocess.This is descr ibed f or axisymmetr ic swir ling flo ws in Impr oving S olution S tabilit y by Gradually Incr easing the R otational or S wirl Speed (p.1217 ). 9.3.1.3. Flows Requiring a Mo ving R efer enc e Frame If your flo w in volves a r otating b oundar y tha t mo ves thr ough the fluid (f or e xample , an imp eller blade or a gr ooved or not ched sur face), you must use a mo ving r eference frame t o mo del the pr oblem. Such applic ations ar e descr ibed in detail in Introduc tion (p.1227 ). If you ha ve mor e than one r otating boundar y (for e xample , several imp ellers in a r ow), you c an use multiple r eference frames (descr ibed in The M ultiple R eference Frame M odel (p.1237 )) or mixing planes (descr ibed in The M ixing P lane Model (p.1239 )). 9.3.2. Turbulenc e M odeling in S wirling F lows If you ar e mo deling turbulen t flo w with a signific ant amoun t of swir l (for e xample , cyclone flo ws, swir ling jets), you should c onsider using one of ANSY S Fluen t’s ad vanced turbulenc e mo dels: the RNG - mo del, realizable - mo del, or R eynolds str ess mo del. The appr opriate choic e dep ends on the strength of the swir l, which c an b e gauged b y the swir l numb er.The swir l numb er is defined as the ratio of the axial flux of angular momen tum t o the axial flux of axial momen tum: (9.15) wher e is the h ydraulic r adius . For flo ws with w eak t o mo derate swir l ( ), both the RNG - mo del and the r ealizable - mo del yield appr eciable impr ovemen ts over the standar d - mo del. See RNG k- ε Model and Realizable k-ε ModelSwirl Modific ation (p.1440 ) for details ab out these mo dels . For highly swir ling flo ws ( ), the R eynolds str ess mo del (RSM) is str ongly r ecommended .The eff ects of str ong turbulenc e anisotr opy can b e mo deled r igor ously only b y the sec ond-momen t closur e adopt ed in the RSM. See Reynolds S tress M odel (RSM) Steps in U sing a Turbulenc e M odel (p.1392 ) for details about this mo del. For swir ling flo ws enc oun tered in de vices such as c yclone separ ators and swir l combust ors, near-w all turbulenc e mo deling is quit e of ten a sec ondar y issue a t most. The fidelit y of the pr edic tions in these cases is mainly det ermined b y the accur acy of the turbulenc e mo del in the c ore region. However, in cases wher e walls ac tively par ticipa te in the gener ation of swir l (tha t is, wher e the sec ondar y flo ws and v ortical flo ws are gener ated b y pr essur e gr adien ts), non-equilibr ium w all func tions c an of ten impr ove the pr edic tions sinc e the y use a la w of the w all for mean v elocity sensitiz ed t o pr essur e gr adien ts. See Near-W all Treatmen ts for Wall-B ounded Turbulen t Flows in the Theor y Guide for additional details about near-w all tr eatmen ts for turbulenc e. 9.3.3. Mesh S etup f or S wirling and Rota ting F lows 9.3.3.1. Coordinat e System R estric tions Recall tha t for an axisymmetr ic pr oblem, the axis of r otation must b e the axis and the mesh must lie on or ab ove the line . 1213Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Swirling and R otating F lows9.3.3.2. Mesh S ensitivit y in S wirling and R otating F lows In addition t o the setup c onstr aint descr ibed ab ove, you should b e aware of the need f or sufficien t resolution in y our mesh when solving flo ws tha t include swir l or r otation. Typic ally, rotating b oundar y layers ma y be very thin, and y our ANSY S Fluen t mo del will r equir e a v ery fine mesh near a r otating wall. In addition, swir ling flo ws will of ten in volve steep gr adien ts in the cir cumf erential v elocity (for example , near the c enterline of a fr ee-v ortex type flo w), and ther efore requir e a fine mesh f or accur ate resolution. 9.3.4. Modeling A xisymmetr ic Flows with S wirl or Rota tion As discussed in Overview of S wirling and R otating F lows (p.1212 ), you c an solv e a 2D axisymmetr ic problem tha t includes the pr edic tion of the cir cumf erential or swir l velocity.The assumption of axisymmetr y implies tha t ther e ar e no cir cumf erential gr adien ts in the flo w, but tha t ther e ma y be nonz ero cir cumf erential v elocities . Examples of axisymmetr ic flo ws involving swir l or r otation ar e de- picted in Figur e 9.10: Rotating F low in a C avity (p.1214 ) and Figur e 9.11: Swirling F low in a G as B urn- er (p.1215 ). Figur e 9.10: Rota ting F low in a C avity Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1214Modeling B asic F luid F lowFigur e 9.11: Swirling F low in a G as Bur ner 9.3.4.1. Problem S etup for A xisymmetric S wirling F lows For axisymmetr ic pr oblems , you must p erform the f ollowing st eps dur ing the pr oblem setup pr ocedur e. (Only those st eps r elevant sp ecific ally t o the setup of axisymmetr ic swir l/rotation ar e list ed her e.You must set up the r est of the pr oblem as usual.) 1.Enable the solution of the momen tum equa tion in the cir cumf erential dir ection b y tur ning on the Axisymmetr ic Swirl option f or Spac e in the Gener al task page . Setup → Gener al → Axisymmetr ic S wirl 2.Define the r otational or swir ling c omp onen t of v elocity, , at inlets or w alls. Setup → Boundar y Conditions Imp ortant Rememb er to use the axis b oundar y type for the axis of r otation. The pr ocedur es for input of r otational v elocities a t inlets and a t walls ar e descr ibed in detail in Defining the Velocity (p.930) and Velocity Conditions f or M oving Walls (p.973). 9.3.4.2. Solution Str ategies for A xisymmetric S wirling F lows The difficulties asso ciated with solving swir ling and r otating flo ws are a r esult of the high degr ee of coupling b etween the momen tum equa tions , which is in troduced when the influenc e of the r otational terms is lar ge. A high le vel of r otation in troduces a lar ge r adial pr essur e gr adien t tha t drives the flo w in the axial and r adial dir ections .This, in tur n, det ermines the distr ibution of the swir l or r otation in the field .This c oupling ma y lead t o instabilities in the solution pr ocess, and y ou ma y requir e sp ecial solution t echniques in or der t o obtain a c onverged solution. Solution t echniques tha t ma y be bene- ficial in swir ling or r otating flo w calcula tions include the f ollowing: 1215Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Swirling and R otating F lows•(Pressur e-based segr egated solv er only) U se the PREST O! scheme (enabled in the Pressur e list f or Spatial Discr etiza tion in the Solution M etho ds Task P age (p.3603 )), which is w ell-suit ed f or the st eep pr essur e gradien ts in volved in swir ling flo ws. •Ensur e tha t the mesh is sufficien tly r efined t o resolv e lar ge gr adien ts in pr essur e and swir l velocity. •(Pressur e-based solv er only) C hange the under-r elaxa tion par amet ers on the v elocities , perhaps t o 0.3–0.5 for the r adial and axial v elocities and 0.8–1.0 f or swir l. •(Pressur e-based solv er only) U se a sequen tial or st ep-b y-step solution pr ocedur e, in which some equa tions are temp orarily lef t inac tive (see b elow). •If nec essar y, star t the c alcula tions using a lo w rotational sp eed or inlet swir l velocity, incr easing the r otation or swir l gradually in or der t o reach the final desir ed op erating c ondition (see b elow). See Using the S olver (p.2559 ) for details on the pr ocedur es used t o mak e these changes t o the solution paramet ers. More details on the st ep-b y-step pr ocedur e and on the gr adual incr ease of the r otational speed ar e pr ovided b elow. 9.3.4.2.1. Step-B y-Step S olution P rocedur es for A xisymmetric S wirling F lows Often, flows with a high degr ee of swir l or r otation will b e easier t o solv e if y ou use the f ollowing step-b y-step solution pr ocedur e, in which only selec ted equa tions ar e lef t active in each st ep.This appr oach allo ws you t o establish the field of angular momen tum, then lea ve it fix ed while y ou up date the v elocity field , and then finally t o couple the t wo fields b y solving all equa tions simultaneously . Imp ortant Since the densit y-based solv ers solv e all the flo w equa tions simultaneously , the f ollowing procedur e applies only t o the pr essur e-based solv er. In this pr ocedur e, you will use the Equa tions ... butt on in the Solution C ontrols Task P age (p.3606 ) to turn individual tr ansp ort equa tions on and off b etween c alcula tions . 1.If your pr oblem in volves inflo w/outflo w, begin b y solving the flo w without r otation or swir l effects.That is, enable the Axisymmetr ic option inst ead of the Axisymmetr ic Swirl option in the Gener al Task Page (p.3235 ), and do not set an y rotating b oundar y conditions .The r esulting flo w-field da ta can b e used as a star ting guess f or the full pr oblem. 2.Enable the Axisymmetr ic Swirl option and set all r otating/swir ling b oundar y conditions . 3.Begin the pr edic tion of the r otating/swir ling flo w by solving only the momen tum equa tion descr ibing the cir cumf erential v elocity.This is the Swirl Velocity listed in the Equa tions list in the Equa tions D ialog Box (p.3609 ). Let the r otation “diffuse ” throughout the flo w field , based on y our b oundar y condition inputs . In a turbulen t flo w simula tion, you ma y also w ant to lea ve the turbulenc e equa tions ac tive dur ing this step.This st ep will establish the field of r otation thr oughout the domain. 4.Turn off the momen tum equa tions descr ibing the cir cumf erential motion ( Swirl Velocity). Leaving the velocity in the cir cumf erential dir ection fix ed, solv e the momen tum and c ontinuit y (pr essur e) equa tions (Flow in the Equa tions list in the Equa tions D ialog Box (p.3609 )) in the other c oordina te dir ections .This step will establish the axial and r adial flo ws tha t are a r esult of the r otation in the field . Again, if your problem in volves turbulen t flo w, you should lea ve the turbulenc e equa tions ac tive dur ing this c alcula tion. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1216Modeling B asic F luid F low5.Turn on all of the equa tions simultaneously t o obtain a fully c oupled solution. Note the under-r elaxa tion controls suggest ed ab ove. In addition t o the st eps ab ove, you ma y want to simplify y our c alcula tion b y solving isother mal flo w before adding hea t transf er or b y solving laminar flo w b efore adding a turbulenc e mo del. These t wo metho ds c an b e used f or an y of the solv ers (tha t is, pressur e-based or densit y-based). 9.3.4.2.2. Impr oving S olution Stabilit y by Gr aduall y Incr easing the R otational or S wirl Speed Because the r otation or swir l defined b y the b oundar y conditions c an lead t o lar ge c omple x forces in the flo w, your ANSY S Fluen t calcula tions will b e less stable as the sp eed of r otation or degr ee of swir l incr eases . Hence, one of the most eff ective controls y ou c an apply t o the solution is t o solv e your r otating flo w pr oblem star ting with a lo w rotational sp eed or swir l velocity and then slo wly increase the magnitude up t o the desir ed le vel.The pr ocedur e for acc omplishing this is as f ollows: 1.Set up the pr oblem using a lo w rotational sp eed or swir l velocity in y our inputs f or b oundar y conditions . The r otation or swir l in this first a ttempt migh t be selec ted as 10% of the ac tual op erating c onditions . 2.Solve the pr oblem a t these c onditions , perhaps using the st ep-b y-step solution str ategy outlined ab ove. 3.Save this initial solution da ta. 4.Modify y our inputs (b oundar y conditions). Incr ease the sp eed of r otation, perhaps doubling it. 5.Restar t the c alcula tion using the solution da ta sa ved in st ep 3 as the initial solution f or the new c alcula- tion. Save the new da ta. 6.Continue t o incr emen t the sp eed of r otation, following st eps 4 and 5, until you r each the desir ed op er- ating c ondition. 9.3.4.2.2.1. Postpr ocessing for A xisymmetric S wirling F lows Reporting of r esults f or axisymmetr ic swir ling flo ws is the same as f or other flo ws.The f ollowing additional v ariables ar e available f or p ostpr ocessing when axisymmetr ic swir l is ac tive: •Swirl Velocity (in the Velocity... categor y) •Swirl-Wall S hear S tress (in the Wall F luxes... categor y) 9.4. Compr essible F lows Compr essibilit y eff ects ar e enc oun tered in gas flo ws at high v elocity and/or in which ther e ar e lar ge pressur e variations .When the flo w velocity appr oaches or e xceeds the sp eed of sound of the gas or when the pr essur e change in the sy stem ( ) is lar ge, the v ariation of the gas densit y with pr essur e has a signific ant impac t on the flo w velocity, pressur e, and t emp erature. Compr essible flo ws create a unique set of flo w ph ysics f or which y ou must b e aware of the sp ecial input r equir emen ts and solution techniques descr ibed in this sec tion. Figur e 9.12: Flow in a C onverging-D iverging N ozzle (p.1218 ) sho ws compr essible flo ws comput ed using ANSY S Fluen t. 1217Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Compr essible F lowsFigur e 9.12: Flow in a C onverging-D iverging N ozzle Information ab out c ompr essible flo ws is pr ovided in the f ollowing subsec tions: 9.4.1. When t o Use the C ompr essible F low M odel 9.4.2. Physics of C ompr essible F lows 9.4.3. Modeling Inputs f or C ompr essible F lows 9.4.4. Floating Op erating P ressur e 9.4.5. Solution S trategies f or C ompr essible F lows 9.4.6. Reporting of R esults f or C ompr essible F lows For mor e inf ormation ab out the theor etical back ground of c ompr essible flo ws, see Compr essible F lows in the Theor y Guide . 9.4.1. When t o Use the C ompr essible F low M odel Compr essible flo ws can b e char acterized b y the v alue of the M ach numb er: (9.16) Here, is the sp eed of sound in the gas: (9.17) and is the r atio of sp ecific hea ts . When the M ach numb er is less than 1.0, the flo w is t ermed subsonic . At Mach numb ers much less than 1.0 ( or so), compr essibilit y eff ects ar e negligible and the v ariation of the gas densit y with pr essur e can saf ely b e ignor ed in y our flo w mo deling . As the M ach numb er appr oaches 1.0 (which is r eferred to as the tr ansonic flo w regime), compr essibilit y eff ects b ecome imp ortant.When the M ach numb er exceeds 1.0, the flo w is t ermed sup ersonic , and ma y contain sho cks and e xpansion fans which c an impac t the flo w pa ttern signific antly. ANSY S Fluen t provides a wide r ange of c ompr essible flo w mo d- eling c apabilities f or subsonic , transonic , and sup ersonic flo ws. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1218Modeling B asic F luid F low9.4.2. Physics of C ompr essible F lows Compr essible flo ws are typic ally char acterized b y the t otal pr essur e and t otal t emp erature of the flow. For an ideal gas , these quan tities c an b e related t o the sta tic pr essur e and t emp erature by the following: (9.18) For c onstan t ,Equa tion 9.18 (p.1219 ) reduc es to (9.19) These r elationships descr ibe the v ariation of the sta tic pr essur e and t emp erature in the flo w as the velocity (M ach numb er) changes under isen tropic c onditions . For e xample , given a pr essur e ratio fr om inlet t o exit (t otal t o sta tic), Equa tion 9.19 (p.1219 ) can b e used t o estima te the e xit M ach numb er tha t would e xist in a one-dimensional isen tropic flo w. For air ,Equa tion 9.19 (p.1219 ) , of 0.5283. This chok ed flo w condition will b e established a t the p oint of minimum flo w ar ea (f or e xample , in the thr oat of a no zzle). In the subsequen t area e xpansion the flo w ma y either acc elerate to a sup ersonic flo w in which the pr essur e will c ontinue t o dr op, or r etur n to subsonic flo w conditions , dec elerating with a pressur e rise. If a sup ersonic flo w is e xposed t o an imp osed pr essur e incr ease , a sho ck will o ccur , with a sudden pr essur e rise and dec eleration acc omplished acr oss the sho ck. 9.4.2.1. Basic E quations for C ompr essible F lows Compr essible flo ws are descr ibed b y the standar d continuit y and momen tum equa tions solv ed b y ANSY S Fluen t, and y ou do not need t o enable an y sp ecial ph ysical mo dels (other than the c ompr essible treatmen t of densit y as detailed b elow).The ener gy equa tion solv ed b y ANSY S Fluen t correctly inc or- porates the c oupling b etween the flo w velocity and the sta tic t emp erature, and should b e ac tivated whene ver y ou ar e solving a c ompr essible flo w. In addition, if y ou ar e using the pr essur e-based solv er, you should enable the visc ous dissipa tion t erms in Equa tion 5.1 in the Theor y Guide , which b ecome imp ortant in high-M ach-numb er flo ws. 9.4.2.2. The C ompr essible F orm of the G as L aw For c ompr essible flo ws, the ideal gas la w is wr itten in the f ollowing f orm: (9.20) wher e is the op erating pr essur e defined in the Operating C onditions D ialog Box (p.3470 ), is the local sta tic pr essur e relative to the op erating pr essur e, is the univ ersal gas c onstan t, and is the molecular w eigh t.The t emp erature, , will b e comput ed fr om the ener gy equa tion. Some c ompr essible flo w pr oblems in volve fluids tha t do not b ehave as ideal gases . For e xample , flow under v ery high-pr essur e conditions c annot t ypic ally b e mo deled accur ately using the ideal-gas as- sumption. Therefore, the r eal gas mo del descr ibed in Real G as M odels (p.1154 ) should b e used inst ead. 1219Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Compr essible F lows9.4.3. Modeling Inputs f or C ompr essible F lows To set up a c ompr essible flo w in ANSY S Fluen t, you must f ollow the st eps list ed b elow. (Only those steps r elevant sp ecific ally t o the setup of c ompr essible flo ws are list ed her e.You must set up the r est of the pr oblem as usual.) 1.Set the Operating P ressur e in the Operating C onditions D ialog Box (p.3470 ). Setup → Boundar y Conditions → Operating C onditions ... (You c an think of as the absolut e sta tic pr essur e at a p oint in the flo w wher e you will define the gauge pr essur e to be zero. See Operating P ressur e (p.1152 ) for guidelines on setting the op er- ating pr essur e. For time-dep enden t compr essible flo ws, you ma y want to sp ecify a floa ting op erating pressur e inst ead of a c onstan t op erating pr essur e. See Floating Op erating P ressur e (p.1221 ) for details .) 2.Enable the solution of the ener gy equa tion. Setup → Models → Energy On 3.(Pressur e-based solv er only) I f you ar e mo deling turbulen t flo w, enable the optional visc ous dissipa tion terms in the ener gy equa tion b y tur ning on Visc ous H eating in the Viscous M odel D ialog Box (p.3253 ). Note tha t these t erms c an b e imp ortant in high-sp eed flo ws. Setup → Models → Visc ous → Edit... This st ep is not nec essar y if y ou ar e using one of the densit y-based solv ers, because the densit y- based solv ers alw ays include the visc ous dissipa tion t erms in the ener gy equa tion. 4.Set the f ollowing it ems in the Create/Edit M aterials D ialog Box (p.3386 ): Setup → Materials → Create/Edit... a.Selec t ideal-gas in the dr op-do wn list ne xt to Densit y. b.Define all r elevant properties (sp ecific hea t, molecular w eigh t, ther mal c onduc tivit y, and so on). 5.Set cell z one c onditions and b oundar y conditions (using the Boundar y Conditions Task P age (p.3479 ) and Cell Z one C onditions Task P age (p.3455 )), being sur e to cho ose a w ell-p osed c ell z one or b oundar y condition combina tion tha t is appr opriate for the flo w regime . See b elow for details . Recall tha t all inputs f or pr essur e (either t otal pr essur e or sta tic pr essur e) must b e relative to the op erating pr essur e, and the t emp erature inputs a t inlets should b e total (stagna tion) t emp eratures,not static t emp eratures. Setup → Cell Z one C onditions Setup → Boundar y Conditions These inputs should ensur e a w ell-p osed c ompr essible flo w pr oblem. You will also w ant to consider special solution par amet er settings , as not ed in Solution S trategies f or C ompr essible F lows (p.1223 ), before beginning the flo w calcula tion. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1220Modeling B asic F luid F low9.4.3.1. Boundar y Conditions for C ompr essible F lows Well-p osed inlet and e xit b oundar y conditions f or c ompr essible flo w ar e list ed b elow: •For flo w inlets: –Pressur e inlet: Inlet t otal t emp erature and t otal pr essur e and , for sup ersonic inlets , static pr essur e –Mass-flo w inlet: Inlet mass flo w and t otal t emp erature •For flo w exits: –Pressur e outlet: Exit sta tic pr essur e (ignor ed if flo w is sup ersonic a t the e xit. All the inf ormation tr avels downstr eam in a sup ersonic r egion, henc e the pr essur e at the outlet c an b e comput ed b y dir ectly e x- trapolating fr om the adjac ent cell c enter [48] (p.4007 ).Therefore, it is not meaning ful t o use the e xit static pr essur e pr escr ibed in the b oundar y conditions task page , and the e xit sta tic pr essur e is ignor ed). –Mass-flo w outlet: Outlet mass flo w It is imp ortant to not e tha t your b oundar y condition inputs f or pr essur e (either t otal pr essur e or static pr essur e) must b e in t erms of gauge pr essur e — tha t is, pressur e relative to the op erating pressur e defined in the Operating C onditions D ialog Box (p.3470 ), as descr ibed ab ove. All temp erature inputs a t inlets should b e total (stagna tion) t emp eratures,not static t emp eratures. 9.4.4. Floating Op erating P ressur e ANSY S Fluen t provides a “floating op erating pr essur e” option t o handle time-dep enden t compr essible flows with a gr adual incr ease in the absolut e pr essur e in the domain. This option is desir able f or slo w subsonic flo ws with sta tic pr essur e build-up , sinc e it efficien tly acc oun ts for the slo w changing of ab- solut e pr essur e without using ac oustic w aves as the tr ansp ort mechanism f or the pr essur e build-up . Examples of t ypic al applic ations include the f ollowing: •combustion or hea ting of a gas in a closed domain •pumping of a gas in to a closed domain 9.4.4.1. Limitations The floa ting op erating pr essur e option should not be used f or tr ansonic or inc ompr essible flo ws. In addition, it c annot b e used if y our mo del includes an y pr essur e inlet , pressur e outlet , exhaust fan, inlet v ent, intake fan, outlet v ent, or pr essur e far field b oundar ies. 9.4.4.2. Theor y The floa ting op erating pr essur e option allo ws ANSY S Fluen t to calcula te the pr essur e rise (or dr op) from the in tegral mass balanc e, separ ately fr om the solution of the pr essur e correction equa tion. When this option is ac tivated, the absolut e pr essur e at each it eration c an b e expressed as (9.21) wher e is the pr essur e relative to the r eference lo cation, which in this c ase is in the c ell with the minimum pr essur e value .Therefore the r eference lo cation itself is floa ting . 1221Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Compr essible F lows is referred t o as the floa ting op erating pr essur e, and is defined as (9.22) wher e is the initial op erating pr essur e and is the pr essur e rise. Including the pr essur e rise in the floa ting op erating pr essur e , rather than in the pr essur e , helps t o pr event roundoff er ror. If the pr essur e rise w ere included in , the c alcula tion of the pressur e gr adien t for the momen tum equa tion w ould giv e an ine xact balanc e due t o pr ecision limits for 32-bit r eal numb ers. 9.4.4.3. Enabling F loating O perating P ressur e When time dep endenc e is ac tive, you c an tur n on the Floating Op erating P ressur e option in the Operating C onditions D ialog Box (p.3470 ). Setup → Boundar y Conditions → Operating C onditions ... (Note tha t the inputs f or Referenc e Pressur e Location will disapp ear when y ou enable Floating Operating P ressur e, sinc e these inputs ar e no longer r elevant.) Imp ortant The floa ting op erating pr essur e option should not be used f or tr ansonic flo ws or f or inc om- pressible flo ws. It is meaning ful only f or slo w subsonic flo ws of ideal gases , when the char acteristic time sc ale is much lar ger than the sonic time sc ale. 9.4.4.4. Setting the Initial Value for the F loating O perating P ressur e When the floa ting op erating pr essur e option is enabled , you must sp ecify a v alue f or the Initial Op- erating P ressur e in the Solution Initializa tion Task P age (p.3620 ). Solution → Initializa tion This initial v alue is st ored in the c ase file with all y our other initial v alues . 9.4.4.5. Storage and R eporting of the F loating O perating P ressur e The cur rent value of the floa ting op erating pr essur e is st ored in the da ta file . If you visit the Operating Conditions D ialog Box (p.3470 ) after a numb er of time st eps ha ve been p erformed , the cur rent value of the Operating P ressur e will b e displa yed. Note tha t the floa ting op erating pr essur e will aut oma tically b e reset t o the initial op erating pr essur e if you r eset the da ta (tha t is, star t over a t the first it eration of the first time st ep). 9.4.4.6. Monit oring A bsolut e Pressur e You c an monit or the absolut e pr essur e dur ing the c alcula tion using the Surface Report Definition Dialog Box (p.3930 ).You c an also gener ate gr aphic al plots or alphanumer ic reports of absolut e pr essur e when y our solution is c omplet e.The Absolut e Pressur e variable is c ontained in the Pressur e... cat- Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1222Modeling B asic F luid F lowegor y of the v ariable selec tion dr op-do wn list tha t app ears in p ostpr ocessing dialo g boxes. See Field Function D efinitions (p.2959 ) for its definition. 9.4.5. Solution S trategies f or C ompr essible F lows The difficulties asso ciated with solving c ompr essible flo ws are a r esult of the high degr ee of c oupling between the flo w velocity, densit y, pressur e, and ener gy.This c oupling ma y lead t o instabilities in the solution pr ocess and , ther efore, ma y requir e sp ecial solution t echniques in or der t o obtain a c onverged solution. In addition, the pr esenc e of sho cks (disc ontinuities) in the flo w in troduces an additional sta- bilit y pr oblem dur ing the c alcula tion. Solution t echniques tha t ma y be beneficial in c ompr essible flo w calcula tions include the f ollowing: •(Pressur e-based solv er only) Initializ e the flo w to be near stagna tion (tha t is v elocity small but not z ero, pressur e to inlet t otal pr essur e, temp erature to inlet t otal t emp erature).Turn off the ener gy equa tion f or the first 50 it erations . Leave the ener gy under-r elaxa tion a t 1. Set the pr essur e under-r elaxa tion t o 0.4, and the momen tum under-r elaxa tion t o 0.3. After the solution stabiliz es and the ener gy equa tion has b een turned on, incr ease the pr essur e under-r elaxa tion t o 0.7. •Set reasonable limits f or the t emp erature and pr essur e (in the Solution Limits D ialog Box (p.3610 )) to avoid solution div ergenc e, esp ecially a t the star t of the c alcula tion. If ANSY S Fluen t prints messages ab out t em- perature or pr essur e being limit ed as the solution nears c onvergenc e, the high or lo w comput ed v alues may be ph ysical, and y ou must change the limits t o allo w these v alues . •If requir ed, begin the c alcula tions using a r educ ed pr essur e ratio a t the b oundar ies, incr easing the pr essur e ratio gr adually in or der t o reach the final desir ed op erating c ondition. If the M ach numb er is lo w, you c an also c onsider star ting the c ompr essible flo w calcula tion fr om an inc ompr essible flo w solution (although the inc ompr essible flo w solution c an in some c ases b e a r ather p oor initial guess f or the c ompr essible c al- cula tion). •In some c ases , computing an in viscid solution as a star ting p oint ma y be helpful. See Using the S olver (p.2559 ) for details on the pr ocedur es used t o mak e these changes t o the solution paramet ers. 9.4.6. Rep orting of Results f or C ompr essible F lows You c an displa y the r esults of y our c ompr essible flo w calcula tions in the same manner tha t you w ould use f or an inc ompr essible flo w.The v ariables list ed b elow ar e of par ticular in terest when y ou mo del compr essible flo w: •Total Temp erature •Total P ressur e •Mach N umb er These v ariables ar e contained in the v ariable selec tion dr op-do wn list tha t app ears in p ostpr ocessing dialo g boxes.Total Temp erature is in the Temp erature... categor y,Total P ressur e is in the Pressur e... categor y, and Mach N umb er is in the Velocity... categor y. See Field F unction D efinitions (p.2959 ) for their definitions . 1223Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Compr essible F lows9.5. Inviscid F lows Inviscid flo w analy sis neglec t the eff ect of visc osity on the flo w and ar e appr opriate for high-R eynolds- numb er applic ations wher e iner tial f orces tend t o domina te visc ous f orces. One e xample f or which an inviscid flo w calcula tion is appr opriate is an aer odynamic analy sis of some high-sp eed pr ojec tile. In a case lik e this , the pr essur e forces on the b ody will domina te the visc ous f orces. Hence, an in viscid ana- lysis will giv e you a quick estima te of the pr imar y forces ac ting on the b ody. After the b ody shap e has been mo dified t o maximiz e the lif t forces and minimiz e the dr ag f orces, you c an p erform a visc ous analy sis t o include the eff ects of the fluid visc osity and turbulen t visc osity on the lif t and dr ag f orces. Another ar ea wher e inviscid flo w analy sis ar e routinely used is t o pr ovide a go od initial solution f or problems in volving c omplic ated flo w ph ysics and/or c omplic ated flo w geometr y. In a c ase lik e this , the viscous f orces ar e imp ortant, but in the ear ly stages of the c alcula tion the visc ous t erms in the momen tum equa tions will b e ignor ed. Onc e the c alcula tion has b een star ted and the r esiduals ar e decr easing , you can tur n on the visc ous t erms (b y enabling laminar or turbulen t flo w) and c ontinue the solution t o convergenc e. For some v ery complic ated flo ws, this is the only w ay to get the c alcula tion star ted. Information ab out in viscid flo ws is pr ovided in the f ollowing subsec tions: 9.5.1. Setting U p an In viscid F low M odel 9.5.2. Solution S trategies f or In viscid F lows 9.5.3. Postpr ocessing f or In viscid F lows For mor e inf ormation ab out the theor etical back ground of in viscid flo ws, see Inviscid F lows in the Theor y Guide . 9.5.1. Setting U p an In viscid F low M odel For in viscid flo w pr oblems , you must p erform the f ollowing st eps dur ing the pr oblem setup pr ocedur e. (Only those st eps r elevant sp ecific ally t o the setup of in viscid flo w ar e list ed her e.You must set up the rest of the pr oblem as usual.) 1.Enable the c alcula tion of in viscid flo w by selec ting Inviscid in the Viscous M odel D ialog Box (p.3253 ). Setup → Models → Visc ous → Model → Inviscid 2.Set b oundar y conditions and flo w pr operties. Setup → Boundar y Conditions Note Walls ar e assumed t o be slip sur faces (the v elocity is not equal t o zero, unlik e visc ous flows) and ther efore ha ve a tangen tial v elocity comput ed based on the solution of the governing equa tions . Setup → Materials 3.Solve the pr oblem and e xamine the r esults . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1224Modeling B asic F luid F low9.5.2. Solution S trategies f or In viscid F lows Since inviscid flo w pr oblems will usually in volve high-sp eed flo w, you ma y ha ve to reduc e the under- relaxa tion fac tors f or momen tum (if y ou ar e using the pr essur e-based solv er) or r educ e the C ourant numb er (if y ou ar e using the densit y-based solv er), in or der t o get the solution star ted. Onc e the flo w is star ted and the r esiduals ar e monot onic ally decr easing , you c an star t incr easing the under-r elaxa tion factors or C ourant numb er back up t o the default v alues . Modific ations t o the under-r elaxa tion fac tors and the C ourant numb er can b e made in the Solution Controls Task P age (p.3606 ). Solution → Controls The solution str ategies f or c ompr essible flo ws apply also t o in viscid flo ws. See Solution S trategies f or Compr essible F lows (p.1223 ) for details . 9.5.3. Postpr ocessing f or In viscid F lows If you ar e in terested in the lif t and dr ag f orces ac ting on y our mo del, you c an use the Force Reports Dialog Box (p.3724 ) to comput e them. Results → Rep orts → Forces Edit... See Forces on B oundar ies (p.2942 ) for details . 1225Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Inviscid F lowsRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1226Chapt er 10: Modeling F lows with M oving Ref erenc e Frames This chapt er pr ovides details ab out the mo ving r eference frame c apabilities in ANSY S Fluen t. The inf ormation in this chapt er is divided in to the f ollowing sec tions: 10.1. Introduction 10.2. Flow in S ingle M oving R eference Frames (SRF) 10.3. Flow in M ultiple M oving R eference Frames 10.1. Introduc tion ANSY S Fluen t solv es the equa tions of fluid flo w and hea t transf er, by default , in a sta tionar y (or iner tial) reference frame . However, ther e ar e man y pr oblems wher e it is ad vantageous t o solv e the equa tions in a mo ving (or non-iner tial) r eference frame . Such pr oblems t ypic ally in volve mo ving par ts (such as rotating blades , imp ellers , and similar t ypes of mo ving sur faces), and it is the flo w ar ound these mo ving parts tha t is of in terest. In most c ases , the mo ving par ts render the pr oblem unst eady when view ed from the sta tionar y frame .With a mo ving r eference frame , however, the flo w ar ound the mo ving par t can (with c ertain r estrictions) b e mo deled as a st eady-sta te pr oblem with r espect to the mo ving fr ame . ANSY S Fluen t’s mo ving r eference frame mo deling c apabilit y allo ws you t o mo del pr oblems in volving moving par ts b y allo wing y ou t o enable mo ving r eference frames in selec ted c ell z ones .When a mo ving reference frame is ac tivated, the equa tions of motion ar e mo dified t o inc orporate the additional acc el- eration t erms tha t occur due t o the tr ansf ormation fr om the sta tionar y to the mo ving r eference frame . By solving these equa tions in a st eady-sta te manner , the flo w ar ound the mo ving par ts can b e mo deled . For man y pr oblems , it ma y be possible t o refer the en tire computa tional domain t o a single mo ving reference frame .This is k nown as the single r eference frame (or SRF) appr oach. The use of the SRF ap- proach is p ossible; provided the geometr y meets c ertain r equir emen ts. For mor e comple x geometr ies, it ma y not b e possible t o use a single r eference frame . In such c ases , you must br eak up the pr oblem into multiple c ell z ones , with w ell-defined in terfaces b etween the z ones .The manner in which the in- terfaces ar e treated leads t o two appr oxima te, steady-sta te mo deling metho ds for this class of pr oblem: the multiple r eference frame (or MRF) appr oach, and the mixing plane appr oach. These appr oaches will be discussed in The M ultiple R eference Frame M odel (p.1237 ) and The M ixing P lane M odel (p.1239 ). If unst eady interaction b etween the sta tionar y and mo ving par ts is imp ortant, you c an emplo y the sliding mesh appr oach t o captur e the tr ansien t behavior of the flo w.The sliding meshing mo del will b e discussed in Modeling F lows Using S liding and D ynamic M eshes (p.1251 ). The pr incipal r eason f or emplo ying a mo ving r eference frame is t o render a pr oblem tha t is unst eady in the sta tionar y (iner tial) fr ame , steady with r espect to the mo ving fr ame . For a st eadily mo ving fr ame (for e xample , the fr ame sp eed is c onstan t), it is p ossible t o transf orm the equa tions of fluid motion t o the mo ving fr ame such tha t steady-sta te solutions ar e possible . By default , ANSY S Fluen t permits the activation of a mo ving r eference frame with a st eady sp eed. If the sp eed is not c onstan t, the tr ansf ormed equa tions will c ontain additional t erms (see Relative Velocity Formula tion in the Theor y Guide ). It should also b e not ed tha t you c an r un an unst eady simula tion in a mo ving r eference frame with c onstan t speed.This w ould b e nec essar y if y ou w anted t o simula te, for e xample , vortex shedding fr om a r otating fan blade .The unst eadiness in this c ase is due t o a na tural fluid instabilit y (vortex gener ation) r ather than induc ed fr om in teraction with a sta tionar y comp onen t. 1227Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.For mor e inf ormation ab out the equa tions f or mo ving r eference frames , see Equa tions f or a M oving Reference Frame in the Theor y Guide . Figur e 10.1: Single C omp onen t (Blo wer Wheel Blade P assage) Figur e 10.2: Multiple C omp onen t (Blo wer Wheel and C asing) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1228Modeling F lows with M oving R eference Frames10.2. Flow in S ingle M oving Ref erenc e Frames (SRF) Many pr oblems p ermit the en tire computa tional domain t o be referred t o a single mo ving r eference frame (henc e the name SRF mo deling). In such c ases , the equa tions giv en in Equa tions f or a M oving Reference Frame are solv ed in all fluid c ell z ones . Steady-sta te solutions ar e possible in SRF mo dels provided suitable b oundar y conditions ar e pr escr ibed. In par ticular , wall b oundar ies must adher e to the f ollowing r equir emen ts: •Any walls tha t are mo ving with the r eference frame c an assume an y shap e. An example w ould b e the blade surfaces asso ciated with a pump imp eller .The no slip c ondition is defined in the r elative frame such tha t the r elative velocity is z ero on the mo ving w alls. •For a r otating pr oblem, you c an define w alls tha t are non-mo ving with r espect to the sta tionar y coordina te system, but these w alls must b e sur faces of r evolution ab out the axis of r otation. Here the no slip c ondition is defined such tha t the absolut e velocity is z ero on the w alls. An example of this t ype of b oundar y would be a c ylindr ical wind tunnel w all tha t sur rounds a r otating pr opeller . Rotationally p eriodic b oundar ies ma y also b e used , but the sur face must b e periodic ab out the axis of rotation. As an e xample , it is v ery common t o mo del flo w thr ough a blade r ow of a turb omachine b y assuming the flo w to be rotationally p eriodic and using a p eriodic domain ab out a single blade .This permits go od resolution of the flo w ar ound the blade without the e xpense of mo deling all blades in the blade r ow (see Figur e 10.3: Single B lade M odel with R otationally P eriodic B oundar ies (p.1229 )). Flow b oundar y conditions in ANSY S Fluen t (inlets and outlets) c an, in most c ases , be pr escr ibed in either the sta tionar y or mo ving fr ames . For e xample , for a v elocity inlet , one c an sp ecify either the r elative velocity or absolut e velocity, dep ending on which is mor e convenien t. For additional inf ormation on these and other b oundar y conditions , see Setting U p a S ingle M oving R eference Frame P roblem (p.1230 ) and Cell Z one and B oundar y Conditions (p.835). Figur e 10.3: Single Blade M odel with Rota tionally P eriodic B oundar ies 10.2.1. Mesh S etup f or a S ingle M oving Ref erenc e Frame It is imp ortant to rememb er the f ollowing c oordina te-sy stem c onstr aints when y ou ar e setting up a problem in volving a mo ving r eference frame f or a r otating pr oblem: •For 2D pr oblems , the axis of r otation must b e par allel t o the axis . 1229Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Flow in S ingle M oving R eference Frames (SRF)•For 2D axisymmetr ic pr oblems , the axis of r otation must b e the axis . •For 3D geometr ies, you should gener ate the mesh with a sp ecific or igin and r otational axis in mind f or the rotating c ell z one . Usually it is c onvenien t to use the or igin of the global c oordina te sy stem (0,0,0) f or the frame or igin, and either the , , or axis f or the r otational axis; however, ANSY S Fluen t can acc ommo date an arbitr ary or igin and r otational axis . With 3D r otating pr oblems , it is also imp ortant to not e tha t if y ou w ant to include w alls tha t ha ve zero velocity in the sta tionar y frame , these w alls must b e a sur face of r evolution with r espect to the axis of rotation. If the sta tionar y walls ar e not sur faces of r evolution, you must enc apsula te the r otating parts with in terface boundar ies, ther eby br eaking y our mo del up in to multiple z ones , and use either the MRF or mixing plane mo dels f or st eady-sta te solutions (see The M ultiple R eference Frame M od- el (p.1237 ) and The M ixing P lane M odel (p.1239 )), or the sliding mesh mo del f or unst eady interaction (see Modeling F lows Using S liding and D ynamic M eshes (p.1251 )). 10.2.2. Setting U p a S ingle M oving Ref erenc e Frame P roblem To mo del a pr oblem in volving a single mo ving r eference frame , follow the st eps outlined b elow. 1.Selec t the Velocity Formula tion to be used when solving: either Rela tive or Absolut e. (See Choosing the R elative or A bsolut e Velocity Formula tion (p.1232 ) for details .) Setup → Gener al (Note tha t this st ep is ir relevant if y ou ar e using one of the densit y-based solv ers; these solv ers alw ays use an absolut e velocity formula tion.) 2.For each c ell z one in the domain, specify the tr ansla tional v elocity of the r eference frame and/or the an- gular v elocity ( ) of the r eference frame and the axis ab out which it r otates. Setup → Cell Z one C onditions a.In the Fluid or Solid dialo g box, specify the Rota tion-A xis Or igin and Rota tion-A xis D irection for the fr ame motion in the Referenc e Frame tab , in or der t o define the axis of r otation. b.Also in the Fluid (Figur e 10.4: The F luid D ialog Box Displa ying F rame M otion Inputs (p.1231 )) or Solid dialo g box, enable the Frame M otion option and then set the Speed under Rota tional Velocity and/or the X,Y, and Z comp onen ts of the Transla tional Velocity in the e xpanded p ortion of the dialo g box under the Referenc e Frame tab . Note tha t the sp eed c an b e sp ecified as a c onstan t value or a tr ansien t profile .The tr ansien t profile ma y be in a file f ormat, as descr ibed in Defining Transien t Cell Z one and B oundar y Conditions (p.1066 ), or a UDF macr o, descr ibed in DEFINE_TRANSIENT_PRO- FILE . Specifying the individual v elocities as either a pr ofile or a UDF allo ws you t o sp ecify a sp ecific input of the fr ame motion individually . However, you c an also sp ecify the fr ame motion inputs via a single user-defined func tion tha t uses the UDF macr o DEFINE_ZONE_MOTION .This ma y pr ove to be quit e convenien t if y ou ar e mo deling a mor e complic ated motion of the mo ving r eference frame , wher e the ho oking of man y diff erent user-defined func tions or pr ofiles c an b e cumb ersome . Note If you decide t o ho ok a UDF , you will no longer ha ve acc ess t o the r otation axis or igin and dir ection, or the v elocities . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1230Modeling F lows with M oving R eference FramesDetails ab out these inputs ar e pr esen ted in Inputs f or F luid Z ones (p.854) and in Inputs f or Solid Z ones (p.859). Details ab out the z one motion UDF c an b e found in DEFINE_ZONE_MOTION in the Fluen t Customiza tion M anual . c.If you need t o swit ch b etween the mo ving r eference frame and mo ving mesh mo dels , simply click the Copy To M esh M otion for zones with a mo ving fr ame of r eference and Copy to Frame M otion for zones with mo ving meshes t o transf er motion v ariables , such as the ax es, frame or igin, and v elocity comp onen ts between the t wo mo dels .The v ariables used f or the or igin, axis , and v elocity comp onen ts, as w ell as f or the UDF DEFINE_ZONE_MOTION will b e copied .This is par ticular ly useful if y ou ar e doing a st eady-sta te MRF simula tion t o obtain an initial solution f or a tr ansien t Moving M esh simula tion in a turb omachine . Figur e 10.4: The F luid D ialo g Box Displa ying F rame M otion Inputs Imp ortant Normally it is not nec essar y to enable the Frame M otion option f or solid z ones , as this is not r equir ed if y ou w ant to do a c onjuga te hea t transf er pr oblem wher e the solid and fluid z ones ar e mo ving t ogether .The c ases in which y ou w ould w ant to enable the Frame M otion option include the f ollowing: 1231Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Flow in S ingle M oving R eference Frames (SRF)•if you in tend t o include the c onvective terms in the ener gy equa tion f or the solid (see Equa tion 5.11 in the Theor y Guide ) •if you ar e running an in trinsic fluid-str ucture-in teraction (FSI) simula tion, and y ou w ant the structural mo del t o acc oun t for rotational f orces when c alcula ting the def ormation of the solid c ell z one (see Modeling F luid-S tructure Interaction (FSI) Within F luen t (p.2329 )) 3.Define the v elocity boundar y conditions a t walls.You c an cho ose t o define either an absolut e velocity or a velocity relative to the mo ving r eference frame (tha t is, relative to the v elocity of the adjac ent cell z one specified in st ep 2). If the w all is mo ving a t the sp eed of the mo ving fr ame (and henc e sta tionar y in the mo ving fr ame), it is c onvenien t to sp ecify a r elative angular v elocity of z ero. Likewise , a w all tha t is sta tionar y in the non-mo ving fr ame of r eference should b e giv en a v elocity of z ero in the absolut e reference frame . Specifying the w all v elocities in this manner ob viates the need t o mo dify these inputs la ter if a change is made in the v elocity of the fluid z one . Details ab out these inputs ar e pr esen ted in Velocity Conditions f or M oving Walls (p.973). 4.Define the b oundar y conditions a t the inlets , as descr ibed in Boundar y Conditions (p.912). For v elocity inlets , you c an cho ose t o define either absolut e velocities or v elocities r elative to the motion of the adjac ent cell z one (sp ecified in st ep 2). Likewise , the t otal pr essur e and flo w dir ection c an b e pr escr ibed in absolut e or relative frames f or pr essur e inlets . Details ab out these inputs ar e pr esen ted in Defining the F low D irection (p.923) and Defining the Velocity (p.930). 10.2.2.1. Choosing the R elativ e or A bsolut e Velocity Formulation It is r ecommended tha t you use the v elocity formula tion tha t will r esult in most of the flo w domain having the smallest v elocities in tha t frame , ther eby reducing the numer ical diffusion in the solution and leading t o a mor e accur ate solution. The absolut e velocity formula tion is pr eferred in applic ations wher e the flo w in most of the domain is not mo ving (f or e xample , a fan in a lar ge r oom). The r elative velocity formula tion is appr opriate when most of the fluid in the domain is mo ving , as in the c ase of a lar ge imp eller in a mixing tank. 10.2.2.1.1. Example A pr oblem with sta tionar y out er w alls and a r otating imp eller c an b e solv ed in a single r eference frame .The e xample is illustr ated in Figur e 10.5: Geometr y with the R otating Imp eller (p.1233 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1232Modeling F lows with M oving R eference FramesFigur e 10.5: Geometr y with the Rota ting Imp eller In case A, it is e xpected tha t only the flo w near the imp eller w ould b e rotating and tha t much of the flo w away from the imp eller w ould ha ve a lo w velocity magnitude in the absolut e frame . Therefore, solving using the absolut e velocity formula tion is r ecommended . In c ase B , most of the flow is e xpected t o be rotating with a v elocity close t o tha t of the imp eller . Hence, the r elative velocity formula tion is appr opriate. In a situa tion b etween c ase A and c ase B , either of the f ormula tions ma y be used . Imp ortant •If the v elocity formula tion is swit ched dur ing the solution pr ocess, ANSY S Fluen t will not transf orm the cur rent solution t o the other fr ame , which c an lead t o lar ge jumps in r esiduals . If changing the fr ame is nec essar y, it is r ecommended tha t you first r einitializ e, and then solv e. •When one of the densit y-based solution algor ithms is used , the absolut e formula tion is alw ays used; the r elative velocity formula tion is not a vailable in the densit y-based solv ers. For v elocity inlets , pressur e inlets , mass-flo w inlets , and w alls, you ma y sp ecify v elocity in either the absolut e or the r elative frame , regar dless of whether the absolut e or r elative velocity formula tion is used in the c omputa tion. For pr essur e outlets , the sp ecified sta tic pr essur e is indep enden t of fr ame . However, when ther e is backflo w at a pr essur e outlet , the sp ecified sta tic pr essur e is used as the t otal pr essur e. For c alcula tions using the absolut e velocity formula tion, the sp ecified sta tic pr essur e is used as the t otal pr essur e in the absolut e frame; for the r elative velocity formula tion, the sp ecified sta tic pr essur e is assumed t o be the t otal pr essur e in the r elative frame . As for the flo w dir ection, ANSY S Fluen t assumes the ab- solut e velocity to be nor mal t o the pr essur e outlet f or the absolut e velocity formula tion; for the r el- ative velocity formula tion, it is the r elative velocity tha t is assumed t o be nor mal t o the pr essur e outlet. 1233Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Flow in S ingle M oving R eference Frames (SRF)10.2.3. Solution S trategies f or a S ingle M oving Ref erenc e Frame The difficulties asso ciated with solving flo ws in mo ving r eference frames ar e similar t o those discussed in Solution S trategies f or A xisymmetr ic Swirling F lows (p.1215 ).The pr imar y issue y ou must c onfr ont is the high degr ee of c oupling b etween the momen tum equa tions when the influenc e of the r otational terms is lar ge. A high degr ee of r otation in troduces a lar ge r adial pr essur e gr adien t tha t drives the flow in the axial and r adial dir ections , ther eby setting up a distr ibution of the swir l or r otation in the field .This c oupling ma y lead t o instabilities in the solution pr ocess, and henc e requir e sp ecial solution techniques t o obtain a c onverged solution. Some t echniques tha t ma y be beneficial include the f ollow- ing: •(Pressur e-based solv er only) C onsider swit ching the fr ame in which v elocities ar e solv ed b y changing the velocity formula tion setting in the Gener al Task P age (p.3235 ). (See Choosing the R elative or A bsolut e Velocity Formula tion (p.1232 ) for details .) •(Pressur e-based segr egated solv er only) U se the PREST O! scheme (enabled in the Solution M etho ds Task Page (p.3603 )), which is w ell-suit ed f or the st eep pr essur e gr adien ts in volved in r otating flo ws. •Ensur e tha t the mesh is sufficien tly r efined t o resolv e lar ge gr adien ts in pr essur e and swir l velocity. •(Pressur e-based , segr egated solv er only) R educ e the under-r elaxa tion fac tors f or the v elocities , perhaps t o 0.3–0.5 or lo wer, if nec essar y. •Begin the c alcula tions using a lo w rotational sp eed, incr easing the r otational sp eed gr adually in or der t o reach the final desir ed op erating c ondition. See Using the S olver (p.2559 ) for details on the pr ocedur es used t o mak e these changes t o the solution paramet ers. 10.2.3.1. Gradual Incr ease of the R otational Sp eed t o Impr ove Solution Stabilit y Because the r otation of the r eference frame and the r otation defined via b oundar y conditions c an lead t o lar ge c omple x forces in the flo w, your ANSY S Fluen t calcula tions ma y be less stable as the speed of r otation (and henc e the magnitude of these f orces) incr eases . One of the most eff ective controls y ou c an e xert on the solution is t o star t with a lo w rotational sp eed and then slo wly incr ease the r otation up t o the desir ed le vel.The pr ocedur e you use t o acc omplish this is as f ollows: 1.Set up the pr oblem using a lo w rotational sp eed in y our inputs f or b oundar y conditions and f or the an- gular v elocity of the r eference frame .The r otational sp eed in this first a ttempt migh t be selec ted as 10% of the ac tual op erating c ondition. 2.Solve the pr oblem a t these c onditions . 3.Save this initial solution da ta. 4.Modify y our inputs (tha t is, boundar y conditions and angular v elocity of the r eference frame). Incr ease the sp eed of r otation, perhaps doubling it. 5.Restar t or c ontinue the c alcula tion using the solution da ta sa ved in S tep 3 as the initial guess f or the new c alcula tion. Save the new da ta. 6.Continue t o incr emen t the r otational sp eed, following S teps 4 and 5, until you r each the desir ed op erating condition. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1234Modeling F lows with M oving R eference Frames10.2.4. Postpr ocessing f or a S ingle M oving Ref erenc e Frame When y ou solv e a pr oblem in a mo ving r eference frame , you c an plot or r eport both absolut e and r e- lative velocities . For all v elocity par amet ers (f or e xample ,Velocity M agnitude and Mach N umb er), corresponding r elative values will b e available f or p ostpr ocessing (f or e xample ,Rela tive Velocity Magnitude and Rela tive M ach N umb er).These v ariables ar e contained in the Velocity... categor y of the v ariable selec tion dr op-do wn list tha t app ears in p ostpr ocessing dialo g boxes. Relative values ar e also a vailable f or p ostpr ocessing of t otal pr essur e, total t emp erature, and an y other par amet ers tha t include a d ynamic c ontribution dep enden t on the r eference frame (f or e xample ,Rela tive Total P ressur e, Rela tive Total Temp erature,Rothalp y). When plotting v elocity vectors, you c an cho ose t o plot v ectors in the absolut e frame (the default), or you c an selec t Rela tive Velocity in the Vectors of drop-do wn list in the Vectors D ialog Box (p.3954 ) to plot v ectors in the mo ving fr ame . If you plot r elative velocity vectors, you migh t want to color the vectors b y relative velocity magnitude (b y cho osing Rela tive Velocity M agnitude in the Color b y list); by default the y will b e color ed b y absolut e velocity magnitude .Figur e 10.6: Absolut e Velocity Vectors (p.1235 ) and Figur e 10.7: Relative Velocity Vectors (p.1236 ) sho w absolut e and r elative velocity vectors in a mo ving domain with a sta tionar y out er w all. Figur e 10.6: Absolut e Velocity Vectors 1235Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Flow in S ingle M oving R eference Frames (SRF)Figur e 10.7: Rela tive Velocity Vectors 10.3. Flow in M ultiple M oving Ref erenc e Frames Many pr oblems in volve multiple mo ving par ts or c ontain sta tionar y sur faces which ar e not sur faces of revolution (and ther efore cannot b e used with the S ingle R eference Frame mo deling appr oach). For these pr oblems , you must br eak up the mo del in to multiple fluid/solid c ell z ones , with in terface boundar ies separ ating the z ones . Zones tha t contain the mo ving c omp onen ts can then b e solv ed using the mo ving r eference frame equa tions ( Equa tions f or a M oving R eference Frame in the Theor y Guide ), wher eas sta tionar y zones c an b e solv ed with the sta tionar y frame equa tions .The manner in which the equa tions ar e treated a t the in terface lead t o two appr oaches tha t are supp orted in ANSY S Fluen t: •Multiple M oving R eference Frames –Multiple R eference Frame M odel (MRF) –Mixing P lane M odel (MPM) •Sliding M esh M odel (SMM) Both the MRF and mixing plane appr oaches ar e steady-sta te appr oxima tions , and diff er pr imar ily in the manner in which c onditions a t the in terfaces ar e treated.These appr oaches will b e discussed in the sections b elow.The sliding mesh mo del appr oach is , on the other hand , inher ently unst eady due t o the motion of the mesh with time .This appr oach is discussed in Modeling F lows Using S liding and Dynamic M eshes (p.1251 ). For additional inf ormation, see the f ollowing sec tions: 10.3.1. The M ultiple R eference Frame M odel 10.3.2. The M ixing P lane M odel 10.3.3. Mesh S etup f or a M ultiple M oving R eference Frame Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1236Modeling F lows with M oving R eference Frames10.3.4. Setting U p a M ultiple M oving R eference Frame P roblem 10.3.5. Solution S trategies f or MRF and M ixing P lane P roblems 10.3.6. Postpr ocessing f or MRF and M ixing P lane P roblems 10.3.7. Frozen G ust / Inlet D isturbanc e Flow M odeling 10.3.1. The M ultiple Ref erenc e Frame M odel Additional inf ormation ab out the MRF mo del is pr esen ted in the f ollowing sec tions: 10.3.1.1. Overview 10.3.1.2. Limita tions 10.3.1.1. Overview The MRF mo del [71] (p.4008 ) is, perhaps , the simplest of the t wo appr oaches f or multiple z ones . It is a steady-sta te appr oxima tion in which individual c ell z ones c an b e assigned diff erent rotational and/or transla tional sp eeds .The flo w in each mo ving c ell z one is solv ed using the mo ving r eference frame equa tions (see Introduc tion (p.1227 )). If the z one is sta tionar y ( ), the equa tions r educ e to their stationar y forms. At the in terfaces b etween c ell z ones , a lo cal reference frame tr ansf ormation is p er- formed t o enable flo w variables in one z one t o be used t o calcula te flux es a t the b oundar y of the adjac ent zone . For mor e inf ormation ab out the MRF in terface formula tion, see The MRF In terface Formula tion in the Theor y Guide . It should b e not ed tha t the MRF appr oach do es not acc oun t for the r elative motion of a mo ving z one with r espect to adjac ent zones (which ma y be mo ving or sta tionar y); the mesh r emains fix ed f or the computa tion. This is analo gous t o freezing the motion of the mo ving par t in a sp ecific p osition and obser ving the instan taneous flo wfield with the r otor in tha t position. Hence, the MRF is of ten r eferred to as the “frozen r otor appr oach. ” While the MRF appr oach is clear ly an appr oxima tion, it c an pr ovide a r easonable mo del of the flo w for man y applic ations . For e xample , the MRF mo del c an b e used f or turb omachiner y applic ations in which r otor-sta tor in teraction is r elatively w eak, and the flo w is r elatively unc omplic ated a t the in terface between the mo ving and sta tionar y zones . In mixing tanks , for e xample , sinc e the imp eller-baffle in- teractions ar e relatively w eak, large-sc ale tr ansien t eff ects ar e not pr esen t and the MRF mo del c an be used . Another p otential use of the MRF mo del is t o comput e a flo w field tha t can b e used as an initial condition f or a tr ansien t sliding mesh c alcula tion. This elimina tes the need f or a star tup c alcula tion. The multiple r eference frame mo del should not b e used , however, if it is nec essar y to ac tually simula te the tr ansien ts tha t ma y occur in str ong r otor-sta tor in teractions , the sliding mesh mo del alone should be used (see Modeling F lows Using S liding and D ynamic M eshes (p.1251 ). For mor e inf ormation ab out and e xamples of multiple mo ving r eference frames , see The M ultiple Reference Frame M odel in the Theor y Guide . 10.3.1.2. Limitations The f ollowing limita tions e xist when using the MRF appr oach: •The in terfaces separ ating a mo ving r egion fr om adjac ent regions must b e or iented such tha t the c omp onen t of the fr ame v elocity nor mal t o the b oundar y is z ero.This means tha t for a tr ansla tionally mo ving fr ame , the mo ving z one’s boundar ies must b e par allel t o the tr ansla tional v elocity vector. For rotating pr oblems , the in terfaces must b e sur faces of r evolution ab out the axis of r otation defined f or the fluid z one . For the 1237Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Flow in M ultiple M oving R eference Framesexample sho wn Figur e 2.4: Geometr y with One R otating Imp eller (in the Theor y Guide ), this r equir es the dashed b oundar y to be cir cular (not squar e or an y other shap e). •Strictly sp eaking, the use of multiple r eference frames is meaning ful only f or st eady flo w. However, ANSY S Fluen t will allo w you t o solv e an unst eady flo w when multiple r eference frames ar e being used . In this case, unst eady terms (as descr ibed in Temp oral D iscretiza tion in the Theor y Guide ) are added t o all the governing tr ansp ort equa tions .You should c arefully c onsider whether this will yield meaning ful r esults for y our applic ation, because , for unst eady flo ws, a sliding mesh c alcula tion will gener ally yield mor e meaning ful r esults than an MRF c alcula tion. •By default , pathlines and par ticle tr ajec tories dr awn b y ANSY S Fluen t use the v elocity relative to the r efer- ence frame motion of the c ell z one . However, for par ticle tr ajec tories, you c an change the r eference frame by either selec ting Track in A bsolut e Frame in the Numer ics tab of the Discr ete Phase M odel dialo g box or using the t ext command define/models/dpm/options/track-in-absolute-frame . Note Only the default b ehavior (tr acking r elative to the mo ving r eference frame) ensur es tha t pathlines and massless par ticles f ollow the flo w in a ph ysically r easonable w ay; tha t is, pathlines or massless par ticles will not hit a w all sur face with an y str ong w all-nor mal velocity comp onen t. Consist ently with this , when a pa thline or par ticle tr ajec tory crosses a boundar y between z ones with diff erent reference frame motion sp ecific ations , you may obser ve a shar p change in par ticle v elocity as a r esult of the c oordina te transf orm- ation. The par ticle injec tion v elocities (sp ecified in the Set Injec tion P roperties D ialog Box (p.3917 )) are in- terpreted in the same w ay as tr acking, tha t is, either r elative to the lo cal fr ame of r eference’s motion specific ation or in absolut e coordina tes. •You c annot accur ately mo del axisymmetr ic swir l in the pr esenc e of multiple r eference frames using the relative velocity formula tion. This is b ecause the cur rent implemen tation do es not apply the tr ansf ormation used in Equa tion 2.16 (in the Theor y Guide ) to the swir l velocity der ivatives. For this situa tion, the absolut e velocity formula tion should b e used . •Transla tional and r otational v elocities ar e assumed t o be constan t (time v arying , are not allo wed). •The r elative velocity formula tion c annot b e used in c ombina tion with the MRF and mix ture mo dels . (For details , see Mixture Model Theor y in the Theor y Guide ). For such c ases , use the absolut e velocity formula tion instead. •You must not ha ve a single in terface between r eference frames wher e par t of the in terface is made up of a coupled t wo-sided w all, while another par t is not c oupled (tha t is, the nor mal in terface treatmen t). In such c ases , you must br eak the in terface up in to two interfaces: one tha t is a c oupled in terface, and the other tha t is a standar d fluid-fluid in terface. See Using a N on-C onformal M esh in ANSY S Fluen t (p.756) for the st eps in volved in setting up a c oupled in terface. Imp ortant You c an swit ch fr om the MRF mo del t o the sliding mesh mo del f or a mor e robust and ac- curate solution, by using the mesh/modify-zones/mrf-to-sliding-mesh text command . See Using S liding M eshes (p.1257 ) for details on ho w to mak e this change in the fluid ’s boundar y conditions . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1238Modeling F lows with M oving R eference Frames10.3.2. The M ixing P lane M odel The mixing plane mo del in ANSY S Fluen t provides an alt ernative to the multiple r eference frame and sliding mesh mo dels f or simula ting flo w thr ough domains with one or mor e regions in r elative motion. Additional inf ormation ab out the mixing plane mo del is pr esen ted in the f ollowing sec tions: 10.3.2.1. Overview 10.3.2.2. Limita tions 10.3.2.1. Overview As discussed in The M ultiple R eference Frame M odel (p.1237 ), the MRF mo del is applic able when the flow at the in terface between adjac ent mo ving/sta tionar y zones is near ly unif orm (“ mixed out ”). If the flo w at this in terface is not unif orm, the MRF mo del ma y not pr ovide a ph ysically meaning ful solution. The sliding mesh mo del (see Modeling F lows Using S liding and D ynamic M eshes (p.1251 )) may be appr opriate for such c ases , but in man y situa tions it is not pr actical to emplo y a sliding mesh. For e xample , in a multistage turb omachine , if the numb er of blades is diff erent for each blade r ow, a lar ge numb er of blade passages is r equir ed in or der t o main tain cir cumf erential p eriodicit y. Moreover, sliding mesh c alcula tions ar e nec essar ily unst eady, and ther efore requir e signific antly mor e computa tion to achie ve a final, time-p eriodic solution. For situa tions wher e using the sliding mesh mo del is not feasible , the mixing plane mo del c an b e a c ost-eff ective alt ernative. In the mixing plane appr oach, each fluid z one is tr eated as a st eady-sta te pr oblem. Flow-field da ta from adjac ent zones ar e passed as b oundar y conditions tha t are spa tially a veraged or “mixed” at the mixing plane in terface.This mixing r emo ves an y unst eadiness tha t would ar ise due t o cir cumf erential variations in the passage-t o-passage flo w field (f or e xample , wakes, sho ck w aves, separ ated flo w), ther efore yielding a st eady-sta te result. Despit e the simplific ations inher ent in the mixing plane model, the r esulting solutions c an pr ovide r easonable appr oxima tions of the time-a veraged flo w field . 10.3.2.2. Limitations Note the f ollowing limita tions of the mixing plane mo del: •The LES turbulenc e mo del c annot b e used with the mixing plane mo del. •The mo dels f or sp ecies tr ansp ort and c ombustion c annot b e used with the mixing plane mo del. •The VOF multiphase mo del c annot b e used with the mixing plane mo del. •The discr ete phase mo del c annot b e used with the mixing plane mo del f or coupled flo ws. Non-c oupled computa tions c an b e done , but y ou should not e tha t the par ticles lea ve the domain of the mixing plane . You c an find mor e inf ormation ab out the f ollowing t opics in the Theor y Guide : Rotor and S tator D omains The M ixing P lane C oncept Choosing an A veraging M etho d Mixing P lane A lgor ithm of ANSY S Fluen t Mass C onser vation Swirl Conser vation Total En thalp y Conser vation 1239Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Flow in M ultiple M oving R eference Frames10.3.3. Mesh S etup f or a M ultiple M oving Ref erenc e Frame Two mesh setup metho ds ar e available . Choose the metho d tha t is appr opriate for y our mo del, noting the r estrictions in Limita tions (p.1237 ). •If the b oundar y between t wo zones tha t are in diff erent reference frames is c onformal (tha t is, the mesh node lo cations ar e iden tical at the b oundar y wher e the t wo zones meet), you c an simply cr eate the mesh as usual, with all c ell z ones c ontained in the same mesh file . A diff erent cell z one should e xist f or each portion of the domain tha t is mo deled in a diff erent reference frame . Use an interior zone f or the b oundar y between r eference frames . •If the b oundar y between t wo zones tha t are in diff erent reference frames is non-c onformal (tha t is, the mesh no de lo cations ar e not iden tical at the b oundar y wher e the t wo zones meet), follow the non-c onformal mesh setup pr ocedur e descr ibed in Using a N on-C onformal M esh in ANSY S Fluen t (p.756). 10.3.4. Setting U p a M ultiple M oving Ref erenc e Frame P roblem To lear n mor e ab out setting up a multiple r eference frame pr oblem, see the f ollowing sec tions: 10.3.4.1. Setting U p Multiple R eference Frames 10.3.4.2. Setting U p the M ixing P lane M odel 10.3.4.1. Setting Up Multiple R efer enc e Frames To mo del a pr oblem in volving multiple r eference frames , perform the f ollowing: Imp ortant The mesh-setup c onstr aints for a mo ving r eference frame list ed in Mesh S etup f or a S ingle Moving R eference Frame (p.1229 ) apply t o multiple r eference frames as w ell. 1.Selec t the Velocity Formula tion to be used in the Gener al Task P age (p.3235 ): either Absolut e or Rela tive. (For details , see Choosing the R elative or A bsolut e Velocity Formula tion (p.1232 ).) Setup → Gener al (Note tha t this st ep is ir relevant if y ou ar e using one of the densit y-based solution algor ithms; these algor ithms alw ays use an absolut e velocity formula tion.) 2.For each c ell z one in the domain, specify its tr ansla tional v elocity and/or its angular v elocity ( ) and the axis ab out which it r otates. Setup → Cell Z one C onditions a.If the z one is mo ving , or if y ou plan t o sp ecify c ylindr ical velocity or flo w-dir ection c omp onen ts at inlets t o the z one , you must define the axis of r otation of the fr ame of r eference. In the Fluid or Solid dialo g box, specify the Rota tion-A xis Or igin and Rota tion-A xis D irection under the Referenc e Frame tab . b.In the Fluid (Figur e 10.4: The F luid D ialog Box Displa ying F rame M otion Inputs (p.1231 )) or Solid dialo g box, enable the Frame M otion option. Set the Speed under Rota tional Velocity and/or the X,Y, Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1240Modeling F lows with M oving R eference Framesand Z comp onen ts of the Transla tional Velocity in the e xpanded p ortion of the dialo g box under the Referenc e Frame tab . Note tha t the sp eed c an b e sp ecified as a c onstan t value or a tr ansien t profile .The tr ansien t profile ma y be in a file f ormat, as descr ibed in Defining Transien t Cell Z one and B oundar y Conditions (p.1066 ), or a UDF macr o, descr ibed in DEFINE_TRANSIENT_PROFILE . Specifying the individual v elocities as either a pr ofile or a UDF allo ws you t o sp ecify a sp ecific input of the fr ame motion individually . However, you c an also sp ecify the fr ame motion inputs via a single user-defined func tion tha t uses the UDF macr o DEFINE_ZONE_MOTION .This ma y prove to be quit e convenien t if y ou ar e mo deling a mor e complic ated motion of the mo ving reference frame , wher e the ho oking of man y diff erent user-defined func tions or pr ofiles c an be cumb ersome . Note If you decide t o ho ok a UDF , then y ou will no longer ha ve acc ess t o the r otation axis or igin and dir ection, or the v elocities . Details ab out these inputs ar e pr esen ted in Inputs f or F luid Z ones (p.854) and in Inputs f or Solid Z ones (p.859). Details ab out the z one motion UDF c an b e found in DEFINE_ZONE_MO- TION in the Fluen t Customiza tion M anual . c.To swit ch b etween the MRF and mo ving mesh mo dels , click the Copy To M esh M otion for zones with a mo ving fr ame of r eference and Copy to Frame M otion for zones with mo ving meshes t o transf er motion v ariables , such as the ax es, frame or igin, and v elocity comp onen ts between the t wo models . The v ariables used f or the or igin, axis , and v elocity comp onen ts, as w ell as f or the UDF DEFINE_ZONE_MOTION will b e copied .This is par ticular ly useful if y ou ar e doing a st eady- state MRF simula tion t o obtain an initial solution f or a tr ansien t Moving M esh simula tion in a turb omachine . 3.Define the v elocity boundar y conditions a t walls.You c an cho ose t o define either an absolut e velocity or a v elocity relative to the v elocity of the adjac ent cell z one sp ecified in st ep 2. If the w all is mo ving a t the sp eed of the mo ving fr ame (and henc e sta tionar y relative to the moving fr ame), it is c onvenien t to sp ecify a r elative angular v elocity of z ero. Likewise , a w all tha t is sta tionar y in the non-mo ving fr ame of r eference should b e giv en a v elocity of z ero in the absolut e reference frame . Specifying the w all v elocities in this manner ob viates the need t o mo dify these inputs la ter if a change is made in the r otational v elocity of the fluid z one . An example f or which y ou w ould sp ecify a r elative velocity is as f ollows: If an imp eller is defined as wall-3 and the fluid r egion within the imp eller ’s radius is defined as fluid-5 , you w ould need to sp ecify the angular v elocity and axis of r otation f or fluid-5 and then assign wall-3 a relative velocity of 0. If you la ter w anted t o mo del a diff erent angular v elocity for the imp eller , you w ould need t o change only the angular v elocity of the fluid r egion; you w ould not need t o mo dify the wall v elocity conditions . Details ab out these inputs ar e pr esen ted in Velocity Conditions f or M oving Walls (p.973). 4.Define the b oundar y conditions a t the inlets , as descr ibed in Boundar y Conditions (p.912). For v elocity inlets , you c an cho ose t o define either absolut e velocities or v elocities r elative to the motion of the adja- 1241Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Flow in M ultiple M oving R eference Framescent cell z one (sp ecified in st ep 2). Likewise , the t otal pr essur e and flo w dir ection c an b e pr escr ibed in absolut e or r elative frames f or pr essur e inlets . Details ab out these inputs ar e pr esen ted in Defining the F low D irection (p.923) and Defining the Velocity (p.930). 5.Define the mesh in terfaces using the Mesh In terfaces D ialog Box (p.3852 ) (Figur e 11.10: The M esh In terfaces Dialog Box (p.1260 )). Setup → Mesh In terfaces New... To lear n ho w to use the Mesh In terfaces dialo g box, see Using a N on-C onformal M esh in ANSY S Fluen t (p.756). 6.Initializ e the solution using an absolut e frame of r eference (Figur e 10.8: The S olution Initializa tion Task Page f or M oving R eference Frames (p.1243 )). Solution → Initializa tion Selec t the Absolut e option under Referenc e Frame . If the Rela tive to Cell Z one option is selec ted, the initial flo w field c an c ontain disc ontinuities , which c an c ause c onvergenc e pr oblems in the first f ew it erations . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1242Modeling F lows with M oving R eference FramesFigur e 10.8: The S olution Initializa tion Task P age f or M oving Ref erenc e Frames 10.3.4.2. Setting Up the M ixing P lane Mo del The mo del inputs f or mixing planes ar e pr esen ted in this sec tion. Only those st eps r elevant sp ecific ally to the setup of a mixing plane pr oblem ar e list ed her e. Note tha t the use of w all and p eriodic boundar ies in a mixing plane mo del is c onsist ent with their use when the mo del is not ac tive. 1.Selec t the Absolut e or Rela tive Velocity Formula tion in the Gener al Task P age (p.3235 ), when the pressur e-based solv er is enabled . 1243Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Flow in M ultiple M oving R eference FramesSetup → Gener al Imp ortant When the densit y-based solv er is enabled , only the Absolut e Velocity Formula tion can b e used with the mixing plane mo del. 2.For each c ell z one in the domain, specify its angular v elocity ( ) and the axis ab out which it r otates. Setup → Cell Z one C onditions a.If the z one is r otating , or if y ou plan t o sp ecify c ylindr ical-velocity or flo w-dir ection c omp onen ts at inlets t o the z one , you must define the axis of r otation f or the fr ame of r eference. In the Fluid dialo g box or Solid D ialog Box (p.3467 ), specify the Rota tion-A xis Or igin and Rota tion-A xis D irection under the Referenc e Frame tab . b.In the Fluid (Figur e 10.4: The F luid D ialog Box Displa ying F rame M otion Inputs (p.1231 )) or Solid dialo g box, enable the Frame M otion option and then set the Speed under Rota tional Velocity and/or the X,Y, and Z comp onen ts of the Transla tional Velocity in the e xpanded p ortion of the dialo g box under the Referenc e Frame tab . Imp ortant It is imp ortant to define the axis of r otation f or the c ell z ones on both sides of the mixing plane in terface, including the sta tionar y zone . 3.Define the v elocity boundar y conditions a t walls, as descr ibed in st ep 3 of Setting U p M ultiple R eference Frames (p.1240 ). 4.Define the b oundar y conditions a t the inlets , as descr ibed in Boundar y Conditions (p.912). For v elocity inlets , you c an cho ose t o define either absolut e velocities or v elocities r elative to the motion of the adja- cent cell z one (sp ecified in st ep 2). For pr essur e inlets and mass-flo w inlets , the sp ecific ation of the flo w direction and t otal pr essur e will alw ays be absolut e, because the absolut e velocity formula tion is alw ays used f or mixing plane c alcula tions . For a mass-flo w inlet , you do not need t o sp ecify the mass flo w rate or mass flux. ANSY S Fluen t will aut oma tically selec t the Mass F lux with A verage M ass F lux specific ation metho d and set the c orrect values when y ou cr eate the mixing plane , as descr ibed in More About M ass Flux and A verage M ass F lux (p.938). Details ab out these inputs ar e pr esen ted in Defining the F low D irection (p.923),Defining the Ve- locity (p.930), and Inputs a t Mass-F low Inlet B oundar ies (p.935). Imp ortant Note tha t the outlet b oundar y zone a t the mixing plane in terface must b e defined as a pr essur e outlet , and the inlet b oundar y zone a t the mixing plane in terface must b e defined as either a v elocity inlet (inc ompr essible flo w only), a pr essur e inlet , or a mass- flow inlet. The o verall inlet and e xit b oundar y conditions c an b e an y suitable c ombina- tion p ermitt ed b y the solv er (f or e xample , velocity inlet , pressur e inlet , or mass-flo w inlet; pressur e outlet). Rememb er, however, tha t if mass c onser vation acr oss the mixing Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1244Modeling F lows with M oving R eference Framesplane is imp ortant, you must use a mass-flo w inlet as the do wnstr eam b oundar y; strict mass c onser vation is not main tained acr oss the mixing plane when y ou use a v elocity inlet or pr essur e inlet. 5.Define the mixing planes in the Mixing P lanes D ialog Box (p.3862 ) (Figur e 10.9: The M ixing P lanes D ialog Box (p.1245 )). Domain → Mesh M odels → Mixing P lanes ... Figur e 10.9: The M ixing P lanes D ialo g Box a.Specify the t wo zones tha t mak e up the mixing plane b y selec ting an upstr eam z one in the Upstr eam Zone list and a do wnstr eam z one in the Downstr eam Z one list. It is essen tial tha t the c orrect pairs be chosen fr om these lists (tha t is, tha t the b oundar y zones selec ted lie on the mixing plane in terface). You c an check this b y displa ying the mesh. Setup → Gener al → Displa y... b.(3D only) Indic ate the geometr y of the mixing plane in terface by cho osing one of the options under Mixing P lane G eometr y. A Radial geometr y signifies tha t inf ormation a t the mixing plane in terface is t o be cir cumf er- entially a veraged in to pr ofiles tha t vary in the r adial dir ection, for e xample , , .This is the c ase f or axial-flo w machines , for e xample . 1245Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Flow in M ultiple M oving R eference FramesAn Axial geometr y signifies tha t cir cumf erentially a veraged pr ofiles ar e to be constr ucted tha t vary in the axial dir ection, for e xample , , .This is the situa tion f or a r adial-flo w de vice. Imp ortant Note tha t the r adial dir ection is nor mal t o the r otation axis f or the fluid z one and the axial dir ection is par allel t o the r otation axis . c.(3D only) S et the numb er of Interpolation P oints.This is the numb er of r adial or axial lo cations used in constr ucting the b oundar y pr ofiles f or cir cumf erential a veraging .You should cho ose a numb er that appr oxima tely c orresponds t o the r esolution of the sur face mesh in the r adial or axial dir ection. Note tha t while y ou c an use mor e points if y ou w ant, the r esolution of the b oundar y pr ofile will only be as fine as the r esolution of the sur face mesh itself . In 2D the flo w da ta is a veraged o ver the en tire in terface to cr eate a pr ofile c onsisting of a single da ta p oint. For this r eason y ou do not need t o set the numb er of Interpolation P oints or selec t a Mixing P lane G eometr y in 2D . d.Set the Global P aramet ers for the mixing plane . i.Selec t the Averaging M etho d.The Area averaging metho d is the default metho d. For detailed information ab out each of the Area,Mass, or Mixed-Out options , see Choosing an A veraging Metho d in the Theor y Guide . ii.Set the Under-Relaxa tion par amet er. It is sometimes desir able t o under-r elax the changes in boundar y values a t mixing planes as these ma y change v ery rapidly dur ing the ear ly iterations of the solution and c ause the c alcula tion t o div erge.The changes c an b e relax ed b y sp ecifying an under-r elaxa tion less than 1. The new b oundar y pr ofile v alues ar e then c omput ed using (10.1) wher e is the under-r elaxa tion fac tor. Onc e the flo w field is established , the v alue of can b e incr eased . iii.Click Apply to set the Global P aramet ers. If the Default butt on is visible t o the r ight of the Apply butt on, click ing the Default butt on will r etur n Global P aramet ers back t o their default v alues . The Default butt on will then change t o be a Reset butt on. Clicking the Reset butt on will change the Global P aramet ers back t o the v alues tha t were last applied . e.Click Create to create a new mixing plane . ANSY S Fluen t will name the mixing plane b y combining the names of the z ones selec ted as the Upstr eam Z one and Downstr eam Z one and en ter the new mixing plane in the Mixing P lane list. If you cr eate an inc orrect mixing plane , you c an selec t it in the Mixing P lane list and click the Delet e butt on t o delet e it. 10.3.4.2.1. Mo deling O ptions There ar e two options a vailable f or use with the mixing plane mo del: a fix ed pr essur e level for in- compr essible flo ws, and the swir l conser vation descr ibed in Swirl Conser vation in the Theor y Guide . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1246Modeling F lows with M oving R eference Frames10.3.4.2.1.1. Fixing the P ressur e Level for an Inc ompr essible F low For c ertain turb omachiner y configur ations , such as a t orque c onverter, ther e is no fix ed-pr essur e boundar y when the mixing plane mo del is used .The mixing plane mo del is usually used t o mo del the thr ee in terfaces tha t connec t the c omp onen ts of the t orque c onverter. In this c onfigur ation, the pressur e is no longer fix ed. As a r esult , the pr essur e ma y floa t unb ounded , mak ing it difficult t o obtain a c onverged solution. To resolv e this pr oblem, ANSY S Fluen t off ers an option f or fixing the pr essur e level.When this option is enabled , ANSY S Fluen t will adjust the gauge pr essur e field af ter each it eration b y subtr acting fr om it the pr essur e value in the c ell closest t o the Referenc e Pressur e Location in the Operating C ondi- tions D ialog Box (p.3470 ). Imp ortant This option is a vailable only f or inc ompr essible flo ws calcula ted using the pr essur e-based solv er. To enable the fix ed pr essur e option, use the fix-pressure-level text command: define → mixing-planes → set → fix-pressure-level 10.3.4.2.1.2. Conser ving S wirl A cross the M ixing P lane Conser vation of swir l is imp ortant for applic ations such as t orque c onverters ( Swirl Conser vation in the Theor y Guide ). If you w ant to enable swir l conser vation acr oss the mixing plane , you c an use the c ommands in the conserve-swirl text menu: define → mixing-planes → set → conserve-swirl To tur n on swir l conser vation, use the enable? text command . Onc e the option is tur ned on, you can ask the solv er to report inf ormation ab out the swir l conser vation dur ing the c alcula tion. If you turn on verbosity? , ANSY S Fluen t will r eport for e very iteration the z one ID f or the z one on which the swir l conser vation is ac tive, the upstr eam and do wnstr eam swir l integration p er zone ar ea, and the r atio of upstr eam t o do wnstr eam swir l integration b efore and af ter the c orrection. To obtain a r eport of the swir l integration a t every pr essur e inlet , pressur e outlet , velocity inlet , and mass-flo w inlet in the domain, use the report-swirl-integration command .You c an use this inf ormation t o det ermine the t orque ac ting on each c omp onen t of the turb omachiner y acc ording to Equa tion 2.22 (in the Theor y Guide ). 10.3.4.2.1.3. Conser ving Total E nthalp y Across the M ixing P lane One of the options a vailable in the mixing plane mo del is t o conser ve total en thalp y acr oss the mixing plane .This is a desir able f eature because global par amet ers such as efficienc y are dir ectly related t o the change in t otal en thalp y acr oss a blade r ow or stage . The pr ocedur e for ensur ing c onser vation of t otal en thalp y simply in volves adjusting the do wnstr eam total t emp erature pr ofile such tha t the in tegrated t otal en thalp y ma tches the upstr eam in tegrated total en thalp y. If you w ant to enable t otal en thalp y conser vation, you c an use the c ommands in the conserve- total-enthalpy text menu: 1247Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Flow in M ultiple M oving R eference Framesdefine → mixing-planes → set → conserve-total-enthalpy To tur n on t otal en thalp y conser vation, use the enable? text command . Onc e the option is tur ned on, you c an ask the solv er to report inf ormation ab out the t otal en thalp y conser vation dur ing the calcula tion. If you tur n on verbosity? , ANSY S Fluen t will r eport at every iteration the z one ID f or the z one on which the t otal en thalp y conser vation is ac tive, the upstr eam and do wnstr eam hea t flux, and the r atio of upstr eam t o do wnstr eam hea t flux. 10.3.5. Solution S trategies f or MRF and M ixing P lane P roblems 10.3.5.1. MRF Mo del For multiple mo ving r eference frames , follow the guidelines pr esen ted in Solution S trategies f or a Single M oving R eference Frame (p.1234 ) for a single mo ving r eference frame . Rememb er tha t with multiple z ones , the p ossibilit y exists of in teraction b etween mo ving and sta tionar y comp onen ts.This will manif est itself as p oor or oscilla tory convergenc e. In such c ases , it is str ongly r ecommend tha t the sliding mesh appr oach b e used t o comput e the flo wfield in or der t o resolv e the unst eady inter- actions . 10.3.5.2. Mixing P lane Mo del It should b e emphasiz ed tha t the mixing plane mo del is a r easonable appr oxima tion so long as ther e is no signific ant reverse flo w in the vicinit y of the mixing plane . If signific ant reverse flo w o ccurs , the mixing plane will not b e a sa tisfac tory mo del of the ac tual flo w. In a numer ical simula tion, reverse flow of ten o ccurs dur ing the ear ly stages of the c omputa tion e ven though the flo w at convergenc e is not r eversed .Therefore, it is helpful in these situa tions t o first obtain a pr ovisional solution using fixed conditions a t the r otor-sta tor in terface.The mixing plane mo del c an then b e enabled and the solution r un t o convergenc e. If you ar e using the mass or mix ed-out a veraging metho d and y ou ar e experiencing c onvergenc e problems in the pr esenc e of se vere reverse flo w, initializ e your solution using the default ar ea-a veraging metho d, then swit ch t o mass or mix ed-out a veraging af ter the r everse flo w dies out. Under-r elaxing the changes in the mixing plane b oundar y values c an also help in tr oublesome situ- ations . In man y cases , setting the under-r elaxa tion fac tor to a v alue less than 1 can b e helpful. Onc e the flo w field is established , you c an gr adually incr ease the under-r elaxa tion fac tor. 10.3.6. Postpr ocessing f or MRF and M ixing P lane P roblems When y ou solv e a pr oblem using the multiple r eference frame or mixing plane mo del, you c an plot or report both absolut e and r elative velocities . For all v elocity par amet ers (f or e xample ,Velocity Magnitude and Mach N umb er), corresponding r elative values will b e available f or p ostpr ocessing (for e xample ,Rela tive Velocity M agnitude and Rela tive M ach N umb er).These v ariables ar e contained in the Velocity... categor y of the v ariable selec tion dr op-do wn list tha t app ears in p ostpr ocessing dialo g boxes. Relative values ar e also a vailable f or p ostpr ocessing of t otal pr essur e, total t emp erature, Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1248Modeling F lows with M oving R eference Framesand an y other par amet ers tha t include a d ynamic c ontribution dep enden t on the r eference frame (f or example ,Rela tive Total P ressur e,Rela tive Total Temp erature). Imp ortant Relative velocities ar e relative to the tr ansla tional/r otational v elocity of the “reference zone” (specified in the Referenc e Values task page (see Reference Values Task P age (p.3601 ))).The velocity of the r eference zone is the v elocity defined in the Fluid D ialog Box (p.3457 ) for tha t zone . When plotting v elocity vectors, you c an cho ose t o plot v ectors in the absolut e frame (the default), or you c an selec t Rela tive Velocity in the Vectors of drop-do wn list in the Vectors D ialog Box (p.3954 ) to plot v ectors r elative to the tr ansla tional/r otational v elocity of the “reference zone” (specified in the Reference Values Task P age (p.3601 )). If you plot r elative velocity vectors, you migh t want to color the vectors b y relative velocity magnitude (b y cho osing Rela tive Velocity M agnitude in the Color b y list); by default the y will b e color ed b y absolut e velocity magnitude . You c an also gener ate a plot of cir cumf erential a verages in ANSY S Fluen t.This allo ws you t o find the average v alue of a quan tity at several diff erent radial or axial p ositions in y our mo del. ANSY S Fluen t com- putes the a verage of the quan tity over a sp ecified cir cumf erential ar ea, and then plots the a verage against the r adial or axial c oordina te. For mor e inf ormation on gener ating X Y plots of cir cumf erential averages , see XY Plots of C ircumf erential A verages (p.2872 ). For details ab out turb omachiner y-sp ecific p ostpr ocessing f eatures see Turbomachiner y Postpr o- cessing (p.2881 ). 10.3.7. Frozen G ust / Inlet D isturbanc e Flow M odeling To reduc e blade r ow simula tion c ost in turb omachiner y you c an mo del blade r ow coupling (r otor / stator in teraction) using a t echnique k nown as fr ozen gust or inlet disturbanc e flo w mo deling . In this modeling str ategy, the w ake of the upstr eam r ow is obtained usually fr om a st eady-sta te simula tion and imp osed as an inlet pr ofile on the do wnstr eam blade r ow.The same c an b e done with the p otential field fr om the do wnstr eam r ow on an upstr eam r ow. By doing this , the blade r ow in teraction pr oblem is reduc ed t o a single r ow with imp osed inlet and/or outlet pr ofiles . There ar e two possible v ariations of this flo w pr oblem. See Figur e 10.10: Frozen G ust v ariations (p.1250 ). •Wake from a r otor imp osed on sta tor row (c onfigur ation A). •Wake from a sta tor imp osed on r otor row (c onfigur ation B). 1249Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Flow in M ultiple M oving R eference FramesFigur e 10.10: Frozen G ust v ariations The c ommon w orkflow for the fr ozen gust / inlet disturbanc e mo deling appr oach is as f ollows: 1.Perform a st eady-sta te simula tion of the blade r ow in teractions f or the r otor / sta tor configur ation of in terest using either the mixing plane or fr ozen-r otor metho d. See The M ultiple R eference Frame M odel (p.1237 ) or The M ixing P lane M odel (p.1239 ). 2.Extract the w ake pr ofile fr om the neighb oring r ow (w ake of the upstr eam r ow or p otential field of the downstr eam r ow). See Reading and Writing P rofile F iles (p.594). 3.Expand the w ake pr ofile t o full wheel using the Replic ate Profile dialo g box. See Replic ating P rofiles (p.1064 ). 4.Apply the e xpanded pr ofile t o the b oundar y of in terest, typic ally an inlet , on the r otor or sta tor dep ending on the c onfigur ation. 5.The final st ep is dep enden t on which c onfigur ation y ou ar e mo deling . For rotor w ake imp osed on sta tor passage (c onfigur ation A): The pr ofile must b e link ed t o a r eference frame tha t is r otating with the r otor. See Using P ro- files (p.1056 ). For sta tor w ake imp osed on a r otor passage (c onfigur ation B): The motion of the r otor with r espect to the sta tionar y sta tor w ake pr ofile c an b e mo deled using the standar d Mesh M otion feature in F luen t, wher e the r otation of the r otor and the axis of r otation are sp ecified in the fluid c ell z one c onditions . See Defining Z one M otion (p.857). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1250Modeling F lows with M oving R eference FramesChapt er 11: Modeling F lows Using S liding and D ynamic M eshes This chapt er descr ibes the setup and use of the sliding and d ynamic mesh mo dels in ANSY S Fluen t.To learn mor e ab out the theor y of sliding meshes in ANSY S Fluen t, see Sliding M esh Theor y in the Theor y Guide . For mor e inf ormation ab out the theor y behind d ynamic meshes in ANSY S Fluen t, see Dynamic Mesh Theor y in the Theor y Guide . Understanding and using the sliding and def orming mesh mo dels is pr esen ted in the f ollowing sec tions: 11.1. Introduction 11.2. Sliding M esh Examples 11.3. The S liding M esh Technique 11.4. Sliding M esh In terface Shap es 11.5. Using S liding M eshes 11.6. Using D ynamic M eshes 11.1. Introduc tion The sliding mesh mo del allo ws you t o set up a pr oblem in which separ ate zones mo ve relative to each other .The motion c an b e transla tional or r otational. The r elative motion of sta tionar y and mo ving comp onen ts (f or e xample , in a r otating machine) will giv e rise t o transien t interactions . Often, the transien t solution tha t is sough t in a sliding mesh simula tion is time-p eriodic.That is, the tr ansien t solution r epeats with a p eriod related t o the sp eeds of the mo ving domains . The d ynamic mesh mo del allo ws you t o mo ve the b oundar ies of a c ell z one r elative to other b oundar ies of the z one , and t o adjust the mesh acc ordingly .The b oundar ies c an mo ve rigidly with r espect to each other (tha t is, linear or r otational motion), and/or def orm. When deciding whether t o use a sliding mesh v ersus a d ynamic mesh, consider the f ollowing: •Many pr oblems c ould b e solv ed b y either appr oach. •If the pr oblem do es not in volve mesh def ormation, the sliding mesh mo del is r ecommended , as it is simpler and mor e efficien t. 1251Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.•The d ynamic mesh metho d must b e used if the mesh is def orming , or if the mesh motion is a func tion of the solution (f or e xample , the six degr ees of fr eedom solv er). Imp ortant Sliding mesh and d ynamic mesh ar e inc ompa tible if the y are combined within the same c ell zone or adjac ent cell z ones . If you w ant to combine these t wo mo dels within the same c ase file, the y must b e separ ated b y a non-mo ving c ell z one . Note By default , transien t simula tions tha t involve a r otating fluid z one utiliz e a b etter flo w field predic tor tha t can sp eed up the c alcula tion in some flo w simula tions .You c an deac tivate the flo w field pr edic tor b y using the c ommand solve/set/rotating-mesh-flow- predictor? and answ ering no. For e xamples of t ypic al sliding mesh and d ynamic mesh pr oblems , see Introduc tion in the Theor y Guide . 11.2. Sliding M esh E xamples When a time-accur ate solution (r ather than a time-a veraged solution) f or rotor-sta tor in teraction is desir ed, you must use the sliding mesh mo del t o comput e the unst eady flo w field .The sliding mesh mo del is the most accur ate metho d for simula ting flo ws in multiple mo ving r eference frames , but also the most computa tionally demanding . Most of ten, the unst eady solution tha t is sough t in a sliding mesh simula tion is time-p eriodic.That is, the unst eady solution r epeats with a p eriod related t o the sp eeds of the mo ving domains . However, you c an mo del other t ypes of tr ansien ts, including tr ansla ting sliding mesh z ones (f or e xample , two cars or tr ains passing in a tunnel, as sho wn in Figur e 11.1: Two Passing Trains in a Tunnel (p.1252 )). Note that the sliding mesh c an b e mo deled using p eriodic b oundar ies ( Figur e 11.2: Rotor-S tator In teraction (Stationar y Guide Vanes with R otating B lades) (p.1253 )) or a cir cular/c ylindr ical in terface (Fig- ure 11.3: Blower (p.1253 )). Figur e 11.1: Two Passing Trains in a Tunnel Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1252Modeling F lows Using S liding and D ynamic M eshesFigur e 11.2: Rot or-S tator In teraction (S tationar y Guide Vanes with Rota ting Blades) Figur e 11.3: Blo wer Note tha t for flo w situa tions wher e ther e is no in teraction b etween sta tionar y and mo ving par ts (f or example , when ther e is only a r otor), it is not nec essar y to use a sliding mesh, and the mo ving r eference frame mo del is r ecommended . (See Flow in a M oving R eference Frame for details .) If you ar e in terested in a st eady appr oxima tion of the in teraction, you ma y use the multiple r eference frame mo del or the mixing plane mo del, as descr ibed in The M ultiple R eference Frame M odel and The M ixing P lane M odel in the Theor y Guide . 1253Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Sliding M esh Examples11.3. The S liding M esh Technique In the sliding mesh t echnique , two or mor e cell z ones ar e used . (If you gener ate the mesh in each z one indep enden tly, you must mer ge the mesh files pr ior t o star ting the c alcula tion, as descr ibed in Reading Multiple M esh/C ase/D ata Files (p.733) in the U ser’s Guide .) Each c ell z one is b ounded b y at least one “interface zone” wher e it meets the opp osing c ell z one .The in terface zones of adjac ent cell z ones ar e asso ciated with one another t o form a “mesh in terface.”The t wo cell z ones will mo ve relative to each other along the mesh in terface. During the c alcula tion, the c ell z ones slide (tha t is, rotate or tr ansla te) relative to one another along the mesh in terface in discr ete steps.Figur e 11.4: Initial P osition of the M eshes (p.1254 ) and Figur e 11.5: Rotor Mesh S lides with R espect to the S tator (p.1255 ) sho w the initial p osition of t wo meshes and their p ositions after some tr ansla tion has o ccur red. Note tha t all non-c onformal in terfaces will b e aut oma tically up dated (if nec essar y) b y ANSY S Fluen t when the mesh is up dated. As the r otation or tr ansla tion tak es plac e, node alignmen t along the mesh in terface is not r equir ed. Since the flo w is inher ently unst eady, a time-dep enden t solution pr ocedur e is r equir ed. Figur e 11.4: Initial P osition of the M eshes Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1254Modeling F lows Using S liding and D ynamic M eshesFigur e 11.5: Rot or M esh S lides with Resp ect to the S tator 11.4. Sliding M esh In terface Shap es The mesh in terface and the asso ciated in terface zones c an b e an y shap e, provided tha t the t wo in terface boundar ies ar e based on the same geometr y.Figur e 11.6: 2D Linear M esh In terface (p.1255 ) sho ws an example with a linear mesh in terface and Figur e 11.7: 2D C ircular-A rc Mesh In terface (p.1256 ) sho ws a circular-ar c mesh in terface. (In b oth figur es, the mesh in terface is designa ted b y a dashed line .) Figur e 11.6: 2D Linear M esh In terface 1255Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Sliding M esh In terface Shap esFigur e 11.7: 2D C ircular-A rc M esh In terface If Figur e 11.6: 2D Linear M esh In terface (p.1255 ) was e xtruded t o 3D , the r esulting sliding in terface would be a planar r ectangle; if Figur e 11.7: 2D C ircular-A rc Mesh In terface (p.1256 ) was e xtruded t o 3D , the resulting in terface would b e a c ylinder .Figur e 11.8: 3D C onic al M esh In terface (p.1256 ) sho ws an e xample that would use a c onic al mesh in terface. (The slan ted, dashed lines r epresen t the in tersec tion of the conic al in terface with a 2D plane .) Figur e 11.8: 3D C onic al M esh In terface For an axial r otor/sta tor c onfigur ation, in which the r otating and sta tionar y par ts ar e aligned axially inst ead of b eing c oncentric (see Figur e 11.9: 3D P lanar-S ector M esh In terface (p.1257 )), the in terface will b e a Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1256Modeling F lows Using S liding and D ynamic M eshesplanar sec tor.This planar sec tor is a cr oss-sec tion of the domain p erpendicular t o the axis of r otation at a p osition along the axis b etween the r otor and the sta tor. Figur e 11.9: 3D P lanar-S ector M esh In terface 11.5. Using S liding M eshes This sec tion descr ibes ho w to use sliding meshes , including r estrictions and c onstr aints, problem setup , solution str ategies , and p ostpr ocessing . 11.5.1. Requir emen ts, Constr aints, and C onsider ations 11.5.2. Setting U p the S liding M esh P roblem 11.5.3. Solution S trategies f or Sliding M eshes 11.5.4. Postpr ocessing f or Sliding M eshes 11.5.1. Requir emen ts, Constr aints, and C onsider ations Before beginning the pr oblem setup in ANSY S Fluen t, be sur e tha t the mesh y ou ha ve created meets the f ollowing r equir emen ts: •The mesh must ha ve a diff erent cell z one f or each p ortion of the domain tha t is sliding a t a diff erent speed. •The mesh in terface must b e situa ted such tha t ther e is no motion nor mal t o it. •The mesh in terface can b e an y shap e (including a non-planar sur face, in 3D), provided tha t the t wo interface boundar ies ar e based on the same geometr y. If ther e are shar p features in the mesh (f or e xample , 90-degr ee angles), it is esp ecially imp ortant tha t both sides of the in terface closely f ollow tha t feature. •If you cr eate a single mesh with multiple c ell z ones , you must b e sur e tha t each c ell z one has a distinc t fac e zone on the sliding b oundar y.The fac e zones f or two adjac ent cell z ones will ha ve the same p osition and shap e, but one will c orrespond t o one c ell z one and one t o the other . (Note tha t it is also p ossible t o create a separ ate mesh file f or each of the c ell z ones , and then mer ge them as descr ibed in Reading M ultiple Mesh/C ase/D ata Files (p.733).) 1257Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using S liding M eshes•If you ar e mo deling a r otor/sta tor geometr y using p eriodicit y, the p eriodic angle of the mesh ar ound the rotor blade(s) must b e the same as tha t of the mesh ar ound the sta tionar y vane(s). •All periodic z ones must b e correctly or iented (either r otational or tr ansla tional) b efore you cr eate the mesh interface. •Note the f ollowing limita tions if y ou w ant to use the p eriodic r epeats option as par t of the mesh in terface: –The edges of the sec ond in terface zone must b e off set fr om the c orresponding edges of the first in terface zone b y a unif orm amoun t (either a unif orm tr ansla tional displac emen t or a unif orm rotation angle). –Some p ortion of the t wo interface zones must o verlap (tha t is, be spa tially c oinciden t). –The non-o verlapping p ortions of the in terface zones must ha ve iden tical shap e and dimensions a t all times dur ing the mesh motion. –One pair of c onformal p eriodic z ones must b e adjac ent to each of the in terface zones . For e xample , when you c alcula te just one channel and blade of a fan, turbine , and so on, you must ha ve conformal p eriodics on either side of the in terface thr eads .This will not w ork with non-c onformal p eriodics . Note tha t for 3D c ases , you c annot ha ve mor e than one pair of c onformal p eriodic z ones adjac ent to each of the in terface zones . •You must not ha ve a single sliding mesh in terface wher e par t of the in terface is made up of a c oupled t wo- sided w all, while another par t is not c oupled (tha t is, the nor mal in terface treatmen t). In such c ases , you must br eak the in terface up in to two interfaces: one tha t is a c oupled in terface, and the other tha t is a standar d fluid-fluid in terface. See Using a N on-C onformal M esh in ANSY S Fluen t (p.756) for inf ormation about cr eating c oupled in terfaces. •When using the sliding mesh t echnique , mass flux es ar e interpolated fr om the sliding in terface fac es to the sliding b oundar y fac es, which c an aff ect the lo cal mass balanc e at the sliding b oundar y.This c an r esult in pr essur e field oscilla tions a t the sliding b oundar y.These oscilla tions ma y be reduc ed b y ensur ing the surface mesh no de distr ibutions ar e similar on either side of the sliding b oundar ies.You c an use the matching option ( Matching Option (p.748)), wher e applic able , to reduc e solution oscilla tions a t the sliding boundar ies. For details ab out these r estrictions and gener al inf ormation ab out ho w the sliding mesh mo del w orks in ANSY S Fluen t, see The S liding M esh Technique (p.1254 ). 11.5.2. Setting U p the S liding M esh P roblem The st eps f or setting up a sliding mesh pr oblem ar e list ed b elow. (Note tha t this pr ocedur e includes only those st eps nec essar y for the sliding mesh mo del itself ; you must set up other mo dels , boundar y conditions , and so on, as usual.) 1.Enable the appr opriate option f or mo deling tr ansien t flo w. (See Performing Time-D ependen t Calcula- tions (p.2626 ) for details ab out the tr ansien t mo deling c apabilities in ANSY S Fluen t.) Setup → Gener al Analy sis Type → Transien t 2.Set the c ell z one c onditions f or the sliding motion: Setup → Cell Z one C onditions Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1258Modeling F lows Using S liding and D ynamic M eshesIn the Solid D ialog Box (p.3467 ) or Fluid D ialog Box (p.3457 ) of each mo ving fluid or solid z one , enable the Mesh M otion option and set the tr ansla tional and/or r otational v elocity under the Mesh M otion tab. (Note tha t a solid z one c annot mo ve at a diff erent sp eed than an adjac ent fluid z one .) Imp ortant Note tha t simultaneous tr ansla tion and r otation c an b e mo deled only if the r otation axis and the tr ansla tion dir ection ar e the same (tha t is, the or igin is fix ed). Note tha t the sp eed c an b e sp ecified as a c onstan t value or a tr ansien t profile .The tr ansien t profile may be in a file f ormat, as descr ibed in Defining Transien t Cell Z one and B oundar y Conditions (p.1066 ), or a UDF macr o, descr ibed in DEFINE_TRANSIENT_PROFILE in the Fluen t Customiza tion Manual . Specifying the individual v elocities as either a pr ofile or a UDF allo ws you t o sp ecify a single c omp onen t of the fr ame motion individually . However, you c an also sp ecify the fr ame motion using a user-defined func tion. This ma y pr ove to be quit e convenien t if y ou ar e mo deling a mor e complic ated motion of the mo ving r eference frame , wher e the ho oking of man y diff erent user- defined func tions or pr ofiles c an b e cumb ersome . Note If you decide t o ho ok a UDF , then y ou will no longer ha ve acc ess t o the r otation axis or igin and dir ection, or the v elocities . 3.Set the b oundar y conditions f or the sliding motion: Setup → Boundar y Conditions Change the z one Type of the in terface zones of adjac ent cell z ones t o interface in the Boundar y Conditions Task P age (p.3479 ). By default , the v elocity of a w all is set t o zero relative to the motion of the adjac ent mesh. For w alls bounding a mo ving mesh this r esults in a “no-slip ” condition in the r eference frame of the mesh. Therefore, you need not mo dify the w all v elocity boundar y conditions unless the w all is sta tionar y in the absolut e frame , and ther efore mo ving in the r elative frame . See Velocity Conditions f or Moving Walls (p.973) for details ab out w all motion. See Cell Z one and B oundar y Conditions (p.835) for details ab out inputting c ell z one and b oundar y conditions . 4.Define the mesh in terfaces using the Mesh In terfaces D ialog Box (p.3852 ) (Figur e 11.10: The M esh In terfaces Dialog Box (p.1260 )). Setup → Mesh In terfaces New... 1259Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using S liding M eshesFigur e 11.10: The M esh In terfaces D ialo g Box To lear n ho w to use the Mesh In terfaces dialo g box, see Using a N on-C onformal M esh in ANSY S Fluen t (p.756). Note tha t the Interface Options tha t are relevant for sliding meshes ar e Periodic Rep eats,Coupled Wall, and Matching (for mor e inf ormation on these options , see Non-C onformal Mesh C alcula tions (p.742)). 5.Preview the mesh motion using the Zone M otion dialo g box, which c an b e op ened fr om the Run C alcu- lation task page . Solution → Run C alcula tion Preview M esh M otion... For details ab out using the Zone M otion dialo g box, see Previewing the D ynamic M esh (p.1368 ). Imp ortant When y ou ha ve complet ed the pr oblem setup , you should sa ve an initial c ase file so tha t you c an easily r etur n to the or iginal mesh p osition (tha t is, the p ositions b efore an y sliding occurs). The mesh p osition is st ored in the c ase file , so c ase files tha t you sa ve at diff erent times dur ing the tr ansien t calcula tion will c ontain meshes a t diff erent positions . Imp ortant If you w ant to go fr om an MRF mo del setup t o a sliding mesh setup , use the f ollowing t ext command: mesh → modify-zones → mrf-to-sliding-mesh To succ essfully swit ch fr om an MRF t o a sliding mesh, you must pr ovide the ID of the fluid zone . ANSY S Fluen t iden tifies all the z ones b elonging t o this fluid z one , as w ell as fluid zones shar ed in the domain. ANSY S Fluen t then splits these z ones in to walls, after which the w alls ar e slit c onverted t o in terfaces. ANSY S Fluen t then changes the c ell z one c ondition of the fluid z one t o Moving M esh in the Fluid D ialog Box (p.3457 ). Note tha t the in terface Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1260Modeling F lows Using S liding and D ynamic M eshesbetween the c ells z ones should b e an in terior b oundar y.You do not need t o do this if y ou have alr eady created a mesh in terface.The sliding mesh solution t ends t o be mor e robust than the MRF solution. 11.5.3. Solution S trategies f or S liding M eshes You will b egin the sliding mesh c alcula tion b y initializing the solution (as descr ibed in Initializing the Entire Flow Field U sing S tandar d Initializa tion (p.2605 )) and then sp ecifying the time st ep siz e and numb er of time st eps in the Run C alcula tion Task P age (p.3640 ), as f or an y other tr ansien t calcula tion. (See Performing Time-D ependen t Calcula tions (p.2626 ) for details ab out time-dep enden t solutions .) Note tha t the time st ep siz e in the initial c ase file is sa ved without click ing Calcula te. ANSY S Fluen t will iterate on the cur rent time st ep solution un til sa tisfac tory residual r educ tion is achie ved, or the max- imum numb er of it erations p er time st ep is r eached .When it ad vances to the ne xt time st ep, the c ell and w all z ones will aut oma tically b e mo ved acc ording t o the sp ecified tr ansla tional or r otational v elo- cities (as discussed in the pr evious sec tion). The new in terface-zone in tersec tions will b e comput ed automa tically, and r esultan t interior/p eriodic/e xternal b oundar y zones will b e up dated. Note tha t you c an r un the MRF c ase using mesh in terfaces with an appr eciable loss of accur acy, doing so mak es it easier t o later on c onvert to a sliding mesh. Note The sliding mesh c an b e initializ ed with an MRF solution (r ather using S tandar d or H ybrid initializa tions). It is r ecommended tha t you pr eview the sliding mesh motion (as descr ibed in Previewing the D ynamic Mesh (p.1368 )) before beginning y our c alcula tion. This c an c atch pr oblems with the motion sp ecific ation(s) before you b egin the CFD c alcula tion. Rememb er to sa ve the c ase and initial da ta files b efore doing a mesh pr eview sinc e the mesh p osition is alt ered onc e you do the pr eview .You c an r eread the initial condition c ase/da ta files t o get back t o the or iginal mesh p osition. 11.5.3.1. Saving C ase and D ata F iles ANSY S Fluen t’s aut oma tic sa ving of c ase and da ta files (see Automa tic S aving of C ase and D ata Files (p.591)) can b e used with the sliding mesh mo del. This pr ovides a c onvenien t way for y ou t o save results a t succ essiv e time st eps f or la ter p ostpr ocessing . Imp ortant You must sa ve a c ase file each time y ou sa ve a da ta file b ecause the mesh p osition is stored in the c ase file . Since the mesh p osition changes with each time st ep, reading da ta for a giv en time st ep will r equir e the c ase file a t tha t time st ep so tha t the mesh will b e in the pr oper p osition. You should also sa ve your initial c ase file so tha t you c an easily r etur n to the mesh ’s original p osition t o restar t the solution if desir ed. 11.5.3.2. Time-P erio dic S olutions For some pr oblems (f or e xample , rotor-sta tor in teractions), you ma y be in terested in a time-p eriodic solution. That is, the star tup tr ansien t behavior ma y not b e of in terest t o you. Onc e this star tup phase 1261Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using S liding M esheshas passed , the flo w will star t to exhibit time-p eriodic b ehavior. If is the p eriod of unst eadiness , then f or some flo w pr operty at a giv en p oint in the flo w field: (11.1) For rotating pr oblems , the p eriod (in sec onds) c an b e calcula ted b y dividing the sec tor angle of the domain (in r adians) b y the r otor sp eed (in r adians/sec): . For 2D r otor-sta tor pr oblems , , wher e is the pit ch and is the blade sp eed.The numb er of time st eps in a p eriod can be det ermined b y dividing the time p eriod by the time st ep siz e.When the solution field do es not change fr om one p eriod to the ne xt (for e xample , if the change is less than 5%), a time-p eriodic solution has b een r eached . To det ermine ho w the solution changes fr om one p eriod to the ne xt, you must c ompar e the solution at some p oint in the flo w field o ver two periods. For e xample , if the time p eriod is 10 sec onds , you can c ompar e the solution a t a giv en p oint after 22 sec onds with the solution af ter 32 sec onds t o see if a time-p eriodic solution has b een r eached . If not , you c an c ontinue the c alcula tion f or another period and c ompar e the solutions af ter 32 and 42 sec onds , and so on un til you see little or no change from one p eriod to the ne xt.You c an also tr ack global quan tities , such as lif t and dr ag c oefficien ts and mass flo w, in the same manner .Figur e 11.11: Lift Coefficien t Plot f or a Time-P eriodic S olution (p.1262 ) shows a lif t coefficien t plot f or a time-p eriodic solution. Figur e 11.11: Lift Coefficien t Plot f or a Time-P eriodic S olution The final time-p eriodic solution is indep enden t of the time st eps tak en dur ing the initial stages of the solution pr ocedur e.You c an ther efore define “large” time st eps in the initial stages of the c alcu- lation, sinc e you ar e not in terested in a time-accur ate solution f or the star tup phase of the flo w. Starting out with lar ge time st eps will allo w the solution t o become time-p eriodic mor e quick ly. As Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1262Modeling F lows Using S liding and D ynamic M eshesthe solution b ecomes time-p eriodic, however, you should r educ e the time st ep in or der t o achie ve a time-accur ate result. Imp ortant If you ar e solving with sec ond-or der time accur acy, the t emp oral accur acy of the solution will b e aff ected if y ou change the time st ep dur ing the c alcula tion. You ma y star t out with larger time st eps, but y ou should not change the time st ep b y mor e than 20% dur ing the solution pr ocess.You should not change the time st ep a t all dur ing the last se veral p eriods to ensur e tha t the solution has appr oached a time-p eriodic sta te. 11.5.4. Postpr ocessing f or S liding M eshes Postpr ocessing f or sliding mesh pr oblems is the same as f or other tr ansien t problems .You will r ead in the c ase and da ta file f or the time of in terest and displa y and r eport results as usual. For spa tially- periodic pr oblems , you ma y want to use p eriodic r epeats (set in the Views Dialog Box (p.3690 ), as de- scribed in Modifying the View (p.2835 )) to displa y the geometr y.Figur e 11.12: Contours of S tatic P ressur e for the R otor-S tator Example (p.1263 ) sho ws the flo w field f or the r otor-sta tor e xample in Figur e 11.4: Initial Position of the M eshes (p.1254 )) at one instan t in time , using 1 p eriodic r epeat. Figur e 11.12: Contours of S tatic P ressur e for the Rot or-S tator E xample When displa ying v elocity vectors, not e tha t absolut e velocities (tha t is, velocities in the iner tial, or laboratory, reference frame) ar e displa yed b y default. You ma y also cho ose t o displa y relative velocities by selec ting Rela tive Velocity in the Vectors of drop-do wn list in the Vectors D ialog Box (p.3954 ). In this c ase, velocities r elative to the tr ansla tional/r otational v elocity of the “reference zone” (specified in the Reference Values Task P age (p.3601 )) will b e displa yed. (The v elocity of the r eference zone is the velocity defined in the Fluid D ialog Box (p.3457 ) for tha t zone .) Note tha t you c annot cr eate zone sur faces for the in tersec tion b oundar ies (tha t is, the in terior/p eriod- ic/external z ones cr eated fr om the in tersec tion of the in terface zones). You ma y inst ead cr eate zone surfaces for the in terface zones . Data displa yed on these sur faces will b e “one-sided ”.That is, nodes on the in terface zones will “see” only the c ells on one side of the mesh in terface, and sligh t disc ontinu- 1263Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using S liding M eshesities ma y app ear when y ou plot c ontour lines acr oss the in terface. Note also tha t, for non-planar in terface shap es in 3D , you ma y see small gaps in y our plots of filled c ontours .These disc ontinuities and gaps are only gr aphic al in na ture.The solution do es not ha ve these disc ontinuities or gaps .To elimina te these disc ontinuities f or p ostpr ocessing pur poses only , you c an use the define/mesh-inter- faces/enforce-continuity-after-bc? text command , which will ensur e tha t continuit y will take pr ecedenc e over the b oundar y condition. You c an also gener ate a plot of cir cumf erential a verages in ANSY S Fluen t.This allo ws you t o find the average v alue of a quan tity at several diff erent radial or axial p ositions in y our mo del. ANSY S Fluen t com- putes the a verage of the quan tity over a sp ecified cir cumf erential ar ea, and then plots the a verage against the r adial or axial c oordina te. For mor e inf ormation on gener ating X Y plots of cir cumf erential averages , see XY Plots of C ircumf erential A verages (p.2872 ). Sliding mesh r esults c an b e analyz ed b y emplo ying the time a veraging (or RMSE a veraging) option (Data S ampling f or Time S tatistics ) in the Run C alcula tion task page .This will c omput e time a verages for v elocity, pressur e, temp erature, and turbulenc e.You must plan ahead sinc e you ha ve to engage the time a veraging af ter the solution has b ecome time-p eriodic and r un f or a t least one p eriod of the oscilla ting flo w field . 11.6. Using D ynamic M eshes The st eps f or setting up a d ynamic mesh pr oblem ar e list ed b elow. (Note tha t this pr ocedur e includes only those st eps nec essar y for the d ynamic mesh mo del itself ; you must set up other mo dels , cell z one conditions , boundar y conditions , and so on, as usual.) 1.Enable the appr opriate option f or mo deling tr ansien t or st eady flo w in the Gener al Task P age (p.3235 ). Setup → Gener al If your pr oblem in volves a st eady flo w, see Steady-State Dynamic M esh A pplic ations (p.1370 ) for im- portant consider ations . 2.Set cell z one c onditions and b oundar y conditions as r equir ed in the Cell Z one C onditions Task P age (p.3455 ) and Boundar y Conditions Task P age (p.3479 ). Setup → Cell Z one C onditions Setup → Boundar y Conditions See Cell Z one and B oundar y Conditions (p.835) for inf ormation ab out inputting c onditions .The correct wall v elocity is set up aut oma tically when a d ynamic z one is cr eated f or a w all z one and the motion a ttribut es ar e sp ecified , so y ou will not sp ecify w all motion in the Wall dialo g box. If you create a mo ving d ynamic c ell z one , then all w all b oundar ies adjac ent to tha t cell z one will, by default , imp ose the c orrect (mo ving) b oundar y conditions , and it is not nec essar y to declar e these w all z ones as d ynamic z ones . Note tha t if a w all b oundar y mesh is mo ving b ecause it b elongs t o an adjac ent moving d ynamic c ell z one , but the ph ysical b oundar y conditions ar e such tha t the w all is ac tually not mo ving , then y ou will ha ve to declar e this b oundar y as a d ynamic z one and sp ecify tha t the mesh motion is not included in the b oundar y conditions (see Specifying the M otion of D ynamic Zones (p.1345 )). 3.Enable the d ynamic mesh mo del, and sp ecify r elated par amet ers in the Dynamic M esh Task P age (p.3567 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1264Modeling F lows Using S liding and D ynamic M eshesSetup → Dynamic M esh → Dynamic M esh See Setting D ynamic M esh M odeling P aramet ers (p.1266 ) for details . 4.Create the d ynamic z ones f or y our mo del, using the Dynamic M esh Z ones D ialog Box (p.3587 ). Setup → Dynamic M esh → Create/Edit... See Specifying the M otion of D ynamic Z ones (p.1345 ) for details . 5.You c an displa y the motion of the mo ving z ones with pr escr ibed motion t o verify the simula tion setup . Setup → Dynamic M esh → Displa y Zone M otion... See Previewing the D ynamic M esh (p.1368 ) for details . 6.If it is a tr ansien t simula tion, define the e vents tha t will o ccur dur ing the c alcula tion. Setup → Dynamic M esh → Events... See Defining D ynamic M esh E vents (p.1336 ) for details . 7.Save the c ase and da ta. File → Write → Case & D ata... 8.Preview y our d ynamic mesh setup (when the motion is a pr escr ibed motion). See Steady-State Dynamic Mesh A pplic ations (p.1370 ) for pr eviewing y our st eady-sta te dynamic mesh motion and r efer to Previewing the D ynamic M esh (p.1368 ) for details . Setup → Dynamic M esh → Preview M esh M otion... 9.Specify the pr essur e-velocity coupling scheme . For tr ansien t flo w calcula tions , the PISO algor ithm is r ecom- mended , as it is the most efficien t for such c ases (see PISO (p.2571 ) for details). 10.Use the aut oma tic sa ving f eature to sp ecify the file name and fr equenc y with which c ase and da ta files should b e sa ved dur ing the solution pr ocess. Solution → Calcula tion A ctivities → Autosa ve (E very) → Edit... See Automa tic S aving of C ase and D ata Files (p.591) for details ab out the use of this f eature.This provides a c onvenien t way for y ou t o sa ve results a t succ essiv e time st eps f or la ter p ostpr ocessing . Imp ortant You must sa ve a c ase file each time y ou sa ve a da ta file b ecause the mesh p osition is stored in the c ase file . Since the mesh p osition changes with each time st ep, reading da ta for a giv en time st ep will r equir e the c ase file a t tha t time st ep so tha t the mesh will b e in the pr oper p osition. You should also sa ve your initial c ase file so tha t you c an easily retur n to the mesh ’s original p osition t o restar t the solution if desir ed. 1265Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshes11.(optional) I f you w ant to create a gr aphic al anima tion of the mesh o ver time dur ing the solution pr ocedur e, you c an use the Calcula tion A ctivities Task P age (p.3626 ) to set up the gr aphic al displa ys tha t you w ant to use in the anima tion. See Anima ting the S olution (p.2670 ) for details . For additional inf ormation, see the f ollowing sec tions: 11.6.1. Setting D ynamic M esh M odeling P aramet ers 11.6.2. Dynamic M esh U pdate Metho ds 11.6.3. Feature Detection 11.6.4. In-C ylinder S ettings 11.6.5. Six DOF S olver Settings 11.6.6. Implicit U pdate Settings 11.6.7. Contact Detection S ettings 11.6.8. Defining D ynamic M esh E vents 11.6.9. Specifying the M otion of D ynamic Z ones 11.6.10. Previewing the D ynamic M esh 11.6.11. Steady-State Dynamic M esh A pplic ations 11.6.1. Setting D ynamic M esh M odeling P aramet ers To enable the d ynamic mesh mo del, enable Dynamic M esh in the Dynamic M esh Task P age (p.3567 ) (Figur e 11.13: The D ynamic M esh Task P age (p.1267 )). Setup → Dynamic M esh → Dynamic M esh Then, enable the appr opriate options in the Options group b ox. If you ar e mo deling in-c ylinder motion, enable the In-C ylinder option. If you ar e going t o use the six degr ees of fr eedom solv er, then enable the Six DOF option. If you w ant to ha ve the d ynamic mesh up dated dur ing a time st ep (as opp osed to just a t the b eginning of a time st ep), then enable the Implicit U pdate option. More inf ormation about these options and the r elated settings c an b e found in In-C ylinder S ettings (p.1313 ),Six DOF Solver S ettings (p.1328 ), and Implicit U pdate Settings (p.1332 ), respectively. Next, you must selec t the appr opriate mesh up date metho ds in the Mesh M etho ds group b ox, and set the asso ciated par amet ers, if relevant. See Dynamic M esh U pdate M etho ds (p.1267 ) for details . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1266Modeling F lows Using S liding and D ynamic M eshesFigur e 11.13: The D ynamic M esh Task P age 11.6.2. Dynamic M esh U pdate M etho ds Three gr oups of mesh motion metho ds ar e available in ANSY S Fluen t to up date the v olume mesh in the def orming r egions subjec t to the motion defined a t the b oundar ies: •Smoothing M etho ds (p.1268 ) 1267Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshes•Dynamic La yering (p.1285 ) •Remeshing M etho ds (p.1289 ) Note tha t you c an use ANSY S Fluen t’s dynamic mesh mo dels in c onjunc tion with adaption, with the exception of d ynamic la yering (in almost all c ases) and an y remeshing metho d other than C utCell z one remeshing . For mor e inf ormation on the a vailable adaption metho ds, see Hanging N ode A daption and Polyhedr al U nstr uctured M esh A daption in the Theor y Guide . Details on ho w to set up the v arious d ynamic mesh up date metho ds ar e pr ovided in the sec tions tha t follow. 11.6.2.1. Smo othing Metho ds When smo othing is used t o adjust the mesh of a z one with a mo ving and/or def orming b oundar y, the in terior no des of the mesh mo ve, but the numb er of no des and their c onnec tivit y do es not change . In this w ay, the in terior no des “absorb ” the mo vemen t of the b oundar y.To enable smo othing , perform the f ollowing st eps: 1.Enable the Smoothing option in the Mesh M etho ds group b ox of the Dynamic M esh Task P age (p.3567 ). 2.Click the Settings ... butt on t o op en the Mesh M etho d Settings dialo g box. Figur e 11.14: The S moothing Tab of the M esh M etho d Settings D ialo g Box 3.If you w ant diffusion-based smo othing , selec t Diffusion from the Metho d list. Then click the Advanc ed... butt on and define the settings in the Mesh S moothing P aramet ers dialo g box; for details , see Diffusion-B ased S moothing (p.1269 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1268Modeling F lows Using S liding and D ynamic M eshesFigur e 11.15: The M esh S moothing P aramet ers D ialo g Box 4.If you w ant spr ing-based smo othing , selec t Spring/L aplac e/Boundar y Layer from the Metho d list. Then click the Advanc ed... butt on and define the settings in the Mesh S moothing P aramet ers dialo g box; for details , see Spring-B ased S moothing (p.1275 ). 5.If you w ant smo othing using the linear ly elastic solid metho d, selec t Linear ly E lastic S olid from the Metho d list. Then click the Advanc ed... butt on and define the settings in the Mesh Smoothing P aramet ers dialo g box; for details , see Linear ly Elastic S olid B ased S moothing M eth- od (p.1279 ). 6.If you selec ted Diffusion or Linear ly E lastic S olid smo othing and the simula tion in volves p eriodic or quasi-p eriodic motion, you c an sp ecify tha t the smo othing uses a r eference position. This option may impr ove the mesh qualit y consist ency from c ycle t o cycle—see Smoothing fr om a R eference Position (p.1281 ) for details . 7.If you plan t o apply the 2.5D r emeshing metho d (as descr ibed in 2.5D Sur face Remeshing M etho d (p.1308 )), perform the f ollowing st eps t o set up Laplacian smo othing (as descr ibed in Laplacian S moothing M eth- od (p.1282 )). a.Selec t Spring/L aplac e/Boundar y Layer from the Metho d list b.Click the Advanc ed... butt on and define only the Laplac e Node Relaxa tion and the Maximum Numb er of I terations in the Mesh S moothing P aramet ers group b ox (the other settings ar e not r elevant). 8.If you plan t o apply the b oundar y layer smo othing metho d (as descr ibed in Boundar y La yer Smoothing Metho d (p.1282 )), selec t Spring/L aplac e/Boundar y Layer from the Metho d list. 11.6.2.1.1. Diffusion-B ased Smo othing For diffusion-based smo othing , the mesh motion is go verned b y the diffusion equa tion (11.2) 1269Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M esheswher e is the mesh displac emen t velocity.The b oundar y conditions f or Equa tion 11.2 (p.1269 ) are obtained fr om the user-pr escr ibed or c omput ed (six DOF) b oundar y motion. On def orming b ound- aries, the b oundar y conditions ar e such tha t the mesh motion is tangen t to the b oundar y (tha t is, the nor mal v elocity comp onen t vanishes). The Laplac e equa tion Equa tion 11.2 (p.1269 ) then descr ibes how the pr escr ibed b oundar y motion diffuses in to the in terior of the def orming mesh. The diffusion c oefficien t in Equa tion 11.2 (p.1269 ) can b e used t o control ho w the b oundar y motion affects the in terior mesh motion. A c onstan t coefficien t means tha t the b oundar y motion diffuses unif ormly thr oughout the mesh. With a nonunif orm diffusion c oefficien t, mesh no des in r egions with high diffusivit y tend t o mo ve together (tha t is, with less r elative motion). In Fluen t, two diff erent formula tions f or the diffusion c oefficien t are available f or selec tion fr om the Diffusion F unc tion drop-do wn list in the Mesh S moothing P aramet ers D ialog Box (p.3573 ).The first f ormula tion allo ws you t o ha ve the diffusion c oefficien t be a func tion of the Boundar y D istanc e, and is of the f orm (11.3) wher e is a nor maliz ed b oundar y distanc e.The sec ond f ormula tion allo ws you t o ha ve the diffusion coefficien t be a func tion of the Cell Volume , and is of the f orm (11.4) wher e is the nor maliz ed c ell v olume . In b oth Equa tion 11.3 (p.1270 ) and Equa tion 11.4 (p.1270 ), is a user input par amet er. See Diffusivit y Based on B oundar y Distanc e (p.1273 ) and Diffusivit y Based on C ell Volume (p.1275 ) for inf ormation ab out defining the diffusion c oefficien t. ANSY S Fluen t uses diff erent numer ical metho ds t o solv e the v ector Equa tion 11.2 (p.1269 ), dep ending on the elemen t types pr esen t in the mesh. In the absenc e of p olyhedr al elemen ts or elemen ts with hanging no des (tha t is, meshes tha t ha ve under gone hanging no de adaption and some he xcore or CutCell meshes) the equa tion is solv ed using a finit e elemen t discr etiza tion and the displac emen t velocity, , is obtained dir ectly a t each mesh no de. If the mesh c ontains p olyhedr al elemen ts or hanging no des, the equa tion is discr etized using ANSY S Fluen t’s standar d finit e volume metho d and the c ell-c entered solution f or the displac emen t velocity, , is in terpolated on to the no des using in- verse-distanc e-weigh ted a veraging .The no de p ositions ar e then up dated acc ording t o: (11.5) The finit e elemen t discr etiza tion is gener ally sup erior, as the solution is obtained dir ectly a t the nodes and no in terpolation st ep is nec essar y.The finit e volume metho d can b e enf orced f or meshes of all elemen t types b y executing the TUI c ommand: /define/dynamic-mesh/controls/smoothing-parameters/diffusion-fvm? yes With finit e elemen t discr etiza tion, you c an sp ecify the solution metho d used b y the linear solv er for the diffusion-based smo othing c alcula tions . By default , the CG (conjuga te gr adien t) metho d is selec ted from the AMG S tabiliza tion drop-do wn list. This metho d should b e fast er in this c ontext than the other a vailable metho ds, as it tak es ad vantage of the symmetr y of the ma trix used in the linear systems of equa tions of finit e-elemen t-based mesh smo othing . If div ergenc e is det ected with C G, then the gener alized minimal r esidual (GMRES) metho d will b e used f or an it eration as a fallback, and y ou will b e inf ormed in the c onsole tha t a finit e-elemen t-based mesh smo othing c oupled equa tion is b eing stabiliz ed t o enhanc e linear solv er robustness . In r are cases , the C G metho d ma y result in the gener ation of nega tive volume c ells; you ma y be able t o avoid this b y incr easing the Maximum N umb er of I terations from the default of 50 t o a v alue in the r ange of 200–500. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1270Modeling F lows Using S liding and D ynamic M eshesIf the C G metho d continues t o gener ate nega tive volume c ells with a higher numb er of it erations or if y ou r epeatedly see c onsole messages tha t say the GMRES fallback is b eing used , it is r ecommen- ded tha t you selec t GMRES from the AMG S tabiliza tion drop-do wn list. Note tha t the GMRES metho d is mor e robust than the C G metho d, esp ecially f or high-asp ect-ratio meshes; but it is also mor e demanding in t erms of memor y usage and solv er time . Note tha t this dr op-do wn list also allo ws you t o selec t the BCGST AB (bi-c onjuga te gr adien t stabiliz ed) metho d; like the C G metho d, BCGSTAB falls back t o the GMRES metho d for an it eration when div er- genc e is det ected. Computa tionally , solving a PDE f or mesh smo othing is gener ally mor e costly than spr ing-based smo othing . But it t ends t o pr oduce better qualit y meshes than spr ing-based smo othing and of ten allows lar ger b oundar y def ormations b efore br eaking do wn. Figur e 11.16: The Initial M esh (p.1271 ) and Figur e 11.17: Valid M esh A fter 45 D egree R otation U sing D iffusion-B ased S moothing (p.1272 ) sho w a mesh b efore and af ter rotating the b oundar y by 45 degr ees, using diffusion-based smo othing . With spr ing-based smo othing , the same mesh sho ws degener ated c ells af ter a r otation of 40 degr ees (Figur e 11.18: Degener ated M esh A fter 40 D egree R otation U sing S pring-B ased S moothing (p.1272 )). Figur e 11.16: The Initial M esh 1271Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshesFigur e 11.17: Valid M esh A fter 45 D egree Rota tion U sing D iffusion-B ased S moothing Figur e 11.18: Degener ated M esh A fter 40 D egree Rota tion U sing S pring-B ased S moothing It should b e not ed tha t with diffusion-based smo othing the in terior mesh motion is go verned b y the solution t o Equa tion 11.2 (p.1269 ) and the pr escr ibed b oundar y motion, and not b y mesh ir regu- larities . Poor qualit y elemen ts or mesh def ects ar e not smo othed out b y this metho d, but r ather move together with the pr e-comput ed (a t the b egin of each mesh up date) displac emen t velocity . It is also w orth noting tha t the na ture of the diffusion equa tion is such tha t the r esulting solution (tha t is, the displac emen t velocity ) dep ends on the dimensionalit y of the pr oblem and the t ype of b oundar y motion pr escr ibed.To illustr ate the impac t of the t ype of b oundar y motion, consider Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1272Modeling F lows Using S liding and D ynamic M eshesthe goal of b oundar y-distanc e-based diffusion ( Equa tion 11.3 (p.1270 )): to control which par ts of the mesh absorb the b oundar y motion, so tha t you c an pr eser ve the mesh in the vicinit y of the mo ving boundar y (at the e xpense of the in terior of the mesh). For mor e transla tional (pist on-t ype) b oundar y motions , you c an pr eser ve a r easonably “thick ” region of the mesh adjac ent to the b oundar y (tha t is, multiple la yers of c ells); for rotational b oundar y motions , the r ate of dec ay for the solution as y ou move away from the b oundar y is such tha t it c an b e difficult t o pr eser ve even a “thin ” region. For this r eason, mesh smo othing c an handle tr ansla tional b oundar y motions gener ally much b etter than rotational motions . Although it should in most c ases not b e nec essar y, the accur acy of the solution t o the diffusion equa tion go verning the mesh motion c an b e controlled b y defining the Maximum N umb er of I ter- ations and the Rela tive Convergenc e Toler anc e. You c an enable pr inting of smo othing r esiduals in the c onsole b y en tering 1 f or the Verb osit y. For simula tions with p eriodic or quasi-p eriodic motion, you c an impr ove the mesh qualit y consist ency by sp ecifying tha t the diffusion-based smo othing uses a r eference position, as descr ibed in Smoothing fr om a R eference Position (p.1281 ). 11.6.2.1.1.1. Diffusivit y Based on B oundar y Distanc e Using b oundar y-distanc e-based diffusion ( Equa tion 11.3 (p.1270 )) allo ws you t o control ho w the boundar y motion diffuses in to the in terior of the domain as a func tion of b oundar y distanc e. De- creasing the diffusivit y away from the mo ving b oundar y causes those r egions t o absorb mor e of the mesh motion, and b etter pr eser ves the mesh qualit y near the mo ving b oundar y.This is par ticular ly helpful f or a mo ving b oundar y tha t has pr onounc ed geometr ical features (such as shar p corners) along with a pr escr ibed motion tha t is pr edominan tly r otational. You c an manipula te the diffusion c oefficien t (in Equa tion 11.3 (p.1270 )) primar ily b y adjusting the Diffusion P aramet er in the Mesh S moothing P aramet ers D ialog Box (p.3573 ) ( ). A range of 0 t o 2 has b een sho wn t o be of pr actical use . A v alue of 0 (the default v alue) sp ecifies tha t and yields a unif orm diffusion of the b oundar y motion thr oughout the mesh. Higher v alues of preser ve lar ger regions of the mesh near the mo ving b oundar y, and c ause the r egions a way from the mo ving boundar y to absorb mor e of the motion. The f ollowing t wo figur es illustr ate the eff ect of the Diffusion P aramet er on the r esulting mesh for a tr ansla tional (pist on-t ype) b oundar y motion, when the diffusivit y is based on the b oundar y distanc e. In this e xample , an initially unif ormly meshed squar e domain is def ormed b y mo ving the left boundar y to the r ight. 1273Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshesFigur e 11.19: Effect of D iffusion P aramet er of 0 on In terior N ode M otion Figur e 11.20: Effect of D iffusion P aramet er of 1 on In terior N ode M otion Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1274Modeling F lows Using S liding and D ynamic M eshesFor rotational b oundar y motions , a value of 1.5 f or the Diffusion P aramet er is recommended as a go od star ting p oint. Two diff erent metho ds ar e available f or the e valua tion of the b oundar y distanc e if b oundar y-dis- tanc e-based diffusion is used . By default , Fluen t uses the “standar d” boundar y distanc e in Equa- tion 11.3 (p.1270 ), which is the nor maliz ed distanc e to the near est w all b oundar y; not e tha t none of the other b oundar y types (f or e xample , inlets , outlets , symmetr y, and p eriodic b oundar ies) ar e con- sider ed.This metho d is the same as tha t which is used t o evalua te the b oundar y distanc e for turbu- lenc e mo dels . An example of this metho d is sho wn in Figur e 11.20: Effect of D iffusion P aramet er of 1 on In terior N ode M otion (p.1274 ), wher e only the lef t and r ight boundar ies ar e walls.You ha ve the option of enabling the Gener aliz ed B oundar y D istanc e M etho d option inst ead, so tha t is the normaliz ed distanc e to the near est b oundar y tha t is not declar ed as def orming , regar dless of t ype. Both metho ds use the lar gest distanc e found in all def orming c ell z ones t o nor maliz e the v alue . If the gener alized b oundar y distanc e is used , an additional sc alar equa tion f or the b oundar y distanc e will b e solv ed as par t of the solution of Equa tion 11.2 (p.1269 ). 11.6.2.1.1.2. Diffusivit y Based on C ell Volume Using c ell-v olume-based diffusion ( Equa tion 11.4 (p.1270 )) allo ws you t o control ho w the b oundar y motion diffuses in to the in terior of the domain as a func tion of c ell siz e. Decreasing the diffusivit y in lar ger c ells c auses those c ells t o absorb mor e of mesh motion and ther efore better pr eser ves the cell qualit y of smaller c ells. You c an manipula te the diffusion c oefficien t (in Equa tion 11.3 (p.1270 )) by adjusting the Diffusion Paramet er in the Mesh S moothing P aramet ers D ialog Box (p.3573 ) ( ). A v alue of 0 (the default value) sp ecifies tha t and yields a unif orm diffusion of the b oundar y motion thr oughout the mesh. Higher v alues of result in lar ger c ells absorbing mor e of the motion than smaller c ells. Note tha t the c ell v olume used in Equa tion 11.4 (p.1270 ) is the lo cal cell v olume , nor maliz ed b y the average c ell v olume of all def orming c ell z ones . 11.6.2.1.1.3. Applic abilit y of the D iffusion-B ased Smo othing Metho d Diffusion-based mesh smo othing is an alt ernative metho d to spr ing-based smo othing . It is a vailable for all elemen t types, and y ou c an use it t o up date an y cell z one whose b oundar ies ar e mo ving or deforming . Diffusion-based smo othing is c omputa tionally mor e expensiv e than spr ing-based smo othing , but likely r esults in b etter mesh qualit y (esp ecially f or non-t etrahedr al / non-tr iangular c ell z ones , and for p olyhedr al cells in par ticular) and gener ally allo ws for lar ger b oundar y def ormations b efore breaking do wn. Similar t o spr ing-based smo othing , diffusion-based mesh smo othing c an handle tr ansla tional boundar y def ormations much b etter than r otational motions . Diffusion-based smo othing is not c ompa tible with the b oundar y layer smo othing metho d or the face region r emeshing metho d. For mor e inf ormation ab out these metho ds, see Boundar y La yer Smoothing M etho d (p.1282 ) and Face Region R emeshing M etho d (p.1300 ). 11.6.2.1.2. Spring-B ased Smo othing For spr ing-based smo othing , the edges b etween an y two mesh no des ar e idealiz ed as a net work of interconnec ted spr ings .The initial spacings of the edges b efore an y boundar y motion c onstitut e 1275Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshesthe equilibr ium sta te of the mesh. A displac emen t at a giv en b oundar y no de will gener ate a f orce proportional t o the displac emen t along all the spr ings c onnec ted t o the no de. Using H ook’s La w, the f orce on a mesh no de c an b e wr itten as (11.6) wher e and are the displac emen ts of no de and its neighb or , is the numb er of neigh- boring no des c onnec ted t o no de , and is the spr ing c onstan t (or stiffness) b etween no de and its neighb or .The spr ing c onstan t for the edge c onnec ting no des and is defined as (11.7) wher e is the v alue y ou en ter for Spring C onstan t Factor in the Mesh S moothing P aramet ers Dialog Box (p.3573 ). At equilibr ium, the net f orce on a no de due t o all the spr ings c onnec ted t o the no de must b e zero. This c ondition r esults in an it erative equa tion such tha t (11.8) wher e is the it eration numb er. Since displac emen ts ar e known a t the b oundar ies (af ter b oundar y no de p ositions ha ve been up dated), Equa tion 11.8 (p.1276 ) is solv ed using a Jac obi sw eep on all in terior no des. At convergenc e, the p osi- tions ar e up dated such tha t (11.9) wher e and are used t o denot e the p ositions a t the ne xt time st ep and the cur rent time st ep, respectively.The spr ing-based smo othing is sho wn in Figur e 11.21: Spring-B ased S moothing on In- terior N odes: Start (p.1277 ) and Figur e 11.22: Spring-B ased S moothing on In terior N odes: End (p.1277 ) for a c ylindr ical cell z one wher e one end of the c ylinder is mo ving . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1276Modeling F lows Using S liding and D ynamic M eshesFigur e 11.21: Spring-B ased S moothing on In terior N odes: Start Figur e 11.22: Spring-B ased S moothing on In terior N odes: End You c an c ontrol the spr ing stiffness b y adjusting the v alue of the Spring C onstan t Factor between 0 and 1. A v alue of 0 indic ates tha t ther e is no damping on the spr ings , and b oundar y no de displac e- men ts ha ve mor e influenc e on the motion of the in terior no des. A v alue of 1 imp oses the default level of damping on the in terior no de displac emen ts as det ermined b y solving Equa tion 11.8 (p.1276 ). The eff ect of the Spring C onstan t Factor is illustr ated in Figur e 11.23: Interior N odes Ex tend B eyond Boundar y (Spring C onstan t Factor = 1) (p.1278 ) and Figur e 11.24: Interior N odes R emain Within Boundar y (Spring C onstan t Factor = 0) (p.1278 ), which sho w the tr ailing edge of a NA CA-0012 air foil after a c oun ter-clo ckwise r otation of 2.3° and the mesh is smo othed using the spr ing-based 1277Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshessmo other but limit ed t o 20 it erations . Degener ate cells ( Figur e 11.23: Interior N odes Ex tend B eyond Boundar y (Spring C onstan t Factor = 1) (p.1278 )) are created with the default v alue of 1 f or the Spring Constan t Factor, as the in terior no des e xtend b eyond the mo ving b oundar y. However, the or iginal mesh distr ibution ( Figur e 11.24: Interior N odes R emain Within B oundar y (Spring C onstan t Factor = 0) (p.1278 )) is r ecovered if the Spring C onstan t Factor is set t o 0 (tha t is, no damping on the displac e- men t of in terior no des near the air foil sur face). Figur e 11.23: Interior N odes E xtend B eyond B oundar y (S pring C onstan t Factor = 1) Figur e 11.24: Interior N odes Remain Within B oundar y (S pring C onstan t Factor = 0) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1278Modeling F lows Using S liding and D ynamic M eshesYou c an c ontrol the solution of Equa tion 11.8 (p.1276 ) using the v alues of Convergenc e Toler anc e and Maximum N umb er of I terations . ANSY S Fluen t solv es Equa tion 11.8 (p.1276 ) iteratively dur ing each time st ep un til one of the f ollowing cr iteria is met: •The sp ecified numb er of it erations has b een p erformed . •The solution is c onverged f or tha t time st ep: (11.10) wher e is the in terior and def orming no des RMS displac emen t at the first it eration. 11.6.2.1.2.1. Applic abilit y of the Spring-B ased Smo othing Metho d You c an use the spr ing-based smo othing metho d to up date an y cell or fac e zone whose b oundar y is mo ving or def orming . For non-t etrahedr al cell z ones (non-tr iangular in 2D), the spr ing-based metho d can b e used when the f ollowing c onditions ar e met: •The b oundar y of the c ell z one mo ves pr edominan tly in one dir ection (tha t is, no e xcessiv e anisotr opic stretching or c ompr ession of the c ell z one). •The motion is pr edominan tly nor mal t o the b oundar y zone . If these c onditions ar e not met , the r esulting c ells ma y ha ve high sk ewness v alues , sinc e not all possible c ombina tions of no de pairs in non-t etrahedr al cells (or non-tr iangular in 2D) ar e idealiz ed as spr ings . Polyhedr al cells ar e par ticular ly lik ely t o become highly sk ewed with spr ing-based smo othing (r egar dless of whether the pr evious c onditions ar e met), and so the diffusion-based smo othing metho d is gener ally r ecommended f or p olyhedr a (see Diffusion-B ased S moothing (p.1269 )). By default , spr ing-based smo othing is enabled f or all c ell z ones .This is r eflec ted in the Mesh Smoothing P aramet ers D ialog Box (p.3573 ), wher e All is selec ted fr om the Elemen ts list. If you w ant to disable spr ing-based smo othing f or c ell z ones tha t are not en tirely c omp osed of either t etrahedr al or tr iangular c ells, you c an do tha t by selec ting Tet in Tet Z ones in 3D (or Tri in Tri Zones in 2D). If you ha ve mix ed elemen t zones and y ou do not w ant spr ing-based smo othing on all elemen t types, you c an enable spr ing-based smo othing on only the t etrahedr al or tr iangular c ells b y selec ting Tet in M ixed Z ones in 3D (or Tri in M ixed Z ones in 2D). Selec tion of smo othing elemen ts in the Mesh Smoothing P aramet ers D ialog Box (p.3573 ) applies b y default t o all c ell z ones tha t under go spr ing- based smo othing . In or der t o ha ve mor e pr ecise c ontrol, it is p ossible t o overwrite this global selec tion on individual d ynamic c ell z ones (see Deforming M otion (p.1354 )).This giv es, for e xample , the fle xib- ility to suppr ess smo othing in z ones wher e dynamic la yering (see Dynamic La yering (p.1285 )) is used and allo ws at the same time smo othing of non-simple x (tha t is not t etrahedr al or tr iangular) elemen ts in other z ones . 11.6.2.1.3. Linearl y Elastic S olid B ased Smo othing Metho d With mesh smo othing based on the linear ly elastic solid mo del, the mesh motion is go verned b y the f ollowing set of equa tions . 1279Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshes(11.11) wher e is the str ess t ensor , is the str ain t ensor , and is the mesh displac emen t. For the solution of Equa tion 11.11 (p.1280 ) only the r atio b etween the shear mo dulus , , and Lamé’ s first par amet er, , ma tters.This r atio is par amet erized thr ough P oisson ’s ratio ( ): (11.12) You define this pr operty thr ough the Poisson's R atio field in the Mesh S moothing P aramet ers D ialog Box (p.3573 ). Note tha t the linear ly elastic solid mesh smo othing mo del supp orts constan t ma terial properties only .The p ermissible r ange f or Poisson's R atio is b etween -1.0 and 0.5. The b oundar y conditions f or Equa tion 11.11 (p.1280 ) are obtained fr om the user-pr escr ibed or c omput ed (in the c ase of six DOF motion) b oundar y def ormations .These imp osed def ormations ar e transf erred into the in terior of the def orming mesh as if the mesh w as a linear ly elastic solid with the giv en material pr operties. On def orming b oundar ies y ou c an either sp ecify a geometr y along which the mesh c an slide , or lea ve the geometr y unsp ecified . If a geometr y is sp ecified f or the def orming boundar y, then the b oundar y conditions ar e such tha t the def ormation nor mal t o the b oundar y vanishes and the str ess tangen tial t o the b oundar y is z ero. If the geometr y of the def orming boundar y is unsp ecified , then the def orming b oundar y can also def orm in the nor mal dir ection and the b oundar y conditions ar e such tha t the tr action is z ero in all dir ections . See Deforming M o- tion (p.1354 ) for details of ho w to sp ecify geometr y on def orming z ones . The linear sy stem in Equa tion 11.11 (p.1280 ) is solv ed using a finit e elemen t discr etiza tion and the mesh displac emen ts for the in terior and def orming b oundar y no des ar e obtained dir ectly a t the nodes.The accur acy to which the linear sy stem is solv ed c an b e controlled b y the Maximum N umb er of Iterations and the Rela tive Convergenc e Toler anc e. You c an sp ecify the solution metho d used b y the linear solv er for the linear ly elastic solid mesh smo othing c alcula tions . By default , the CG (conjuga te gr adien t) metho d is selec ted fr om the AMG Stabiliza tion drop-do wn list. This metho d should b e fast er in this c ontext than the other a vailable metho ds, as it tak es ad vantage of the symmetr y of the ma trix used in the linear sy stems of equa tions of finit e-elemen t-based mesh smo othing . If div ergenc e is det ected with C G, then the gener alized minimal r esidual (GMRES) metho d will b e used f or an it eration as a fallback, and y ou will b e inf ormed in the c onsole tha t a finit e-elemen t-based mesh smo othing c oupled equa tion is b eing stabiliz ed t o enhanc e linear solv er robustness . In r are cases , the C G metho d ma y result in the gener ation of nega tive volume c ells; you ma y be able t o avoid this b y incr easing the Maximum N umb er of I tera- tions from the default of 50 t o a v alue in the r ange of 200–500. If the C G metho d continues t o gener ate nega tive volume c ells with a higher numb er of inner it erations or if y ou r epeatedly see c onsole messages tha t say the GMRES fallback is b eing used , it is r ecommen- ded tha t you selec t GMRES from the AMG S tabiliza tion drop-do wn list. Note tha t the GMRES metho d is mor e robust than the C G metho d, esp ecially f or high-asp ect-ratio meshes; but it is also mor e demanding in t erms of memor y usage and solv er time . Note tha t this dr op-do wn list also allo ws you t o selec t the BCGST AB (bi-c onjuga te gr adien t stabiliz ed) metho d; like the C G metho d, BCGSTAB falls back t o the GMRES metho d for an it eration when div er- genc e is det ected. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1280Modeling F lows Using S liding and D ynamic M eshesYou c an enable pr inting of smo othing r esiduals in the c onsole b y en tering 1 f or the Verb osit y. For simula tions with p eriodic or quasi-p eriodic motion, you c an impr ove the mesh qualit y consist ency by sp ecifying tha t the linear ly elastic solid mesh smo othing uses a r eference position, as descr ibed in Smoothing fr om a R eference Position (p.1281 ). 11.6.2.1.3.1. Applic abilit y of the Linearl y Elastic S olid B ased Smo othing Metho d Mesh smo othing based on the linear ly elastic solid mo del is an alt ernative metho d to diffusion-based and spr ing-based smo othing . Most of the pr operties and limita tions discussed f or diffusion-based smo othing ( Applic abilit y of the D iffusion-B ased S moothing M etho d (p.1275 )) also apply t o the linear ly elastic solid mo del, par ticular ly the mesh qualit y degr adation f or rotational motions .The linear ly elastic solid mo del is c omputa tionally mor e expensiv e than diffusion-based smo othing , but f or some meshes and mesh motions pr eser ves the mesh qualit y better. The cur rent implemen tation with c onstan t ma terial pr operties c an b e a limita tion c ompar ed with diffusion-based smo othing with non-unif orm diffusivit y. In c ases with r otational b oundar y motion and shar p corners it ma y be ad vantageous t o use diffusion-based smo othing with b oundar y-distanc e- dep enden t diffusivit y. The option t o lea ve the geometr y of def orming fac e zones unsp ecified is only a vailable with the linear ly elastic solid smo othing metho d. The linear ly elastic solid smo othing metho d supp orts tr iangular and quadr ilateral elemen ts in 2D and t etrahedr al, hexahedr al, wedge , and p yramid c ells in 3D . It cannot b e applied if the def orming cell z one c ontains p olyhedr al cells or hanging no des. In such c ases diffusion-based smo othing is recommended . Linear ly elastic solid smo othing is not c ompa tible with the b oundar y layer smo othing metho d or the fac e region r emeshing metho d. For mor e inf ormation ab out these metho ds, see Boundar y La yer Smoothing M etho d (p.1282 ) and Face Region R emeshing M etho d (p.1300 ). 11.6.2.1.4. Smo othing fr om a R efer enc e Position When the mesh smo othing is based on diffusion or the linear ly elastic solid mo del, you ha ve the option of sp ecifying tha t the smo othing uses a r eference position. This c an b e helpful when p erform- ing man y cycles of p eriodic or quasi-p eriodic motion f or sta tionar y or mo ving meshes; for e xample , turb omachiner y rotors with blade flutt er.When y ou ensur e tha t the smo othing is alw ays done fr om the same r eference position, the mesh qualit y ma y remain mor e consist ent from c ycle t o cycle. To use this f eature, enable the Smoothing F rom Ref erenc e Position option in the Mesh S moothing Paramet ers D ialog Box (p.3573 ). Note this option is enabled b y default dur ing the c alcula tion if the case includes a c ell z one tha t has Frame M otion or Mesh M otion enabled with a nonz ero rotational velocity and tha t is also defined as a def orming d ynamic mesh z one .This option is not a vailable if the Layering and/or Remeshing options ar e enabled in the Dynamic M esh task page , or if Dynamic Adaption is enabled in the Adaption C ontrols dialo g box. The r eference position is sa ved the first time y ou p erform smo othing af ter enabling this option. It is recommended tha t you sa ve your c ase / da ta files using the Hier archic al D ata Format (HDF); oth- erwise , the r eference position is not sa ved, and so r estar ting fr om a .cas file will imply tha t a dif- ferent reference position is used af ter restar t.This still pr ovides the b enefit of c onsist ent qualit y, but the r esulting meshes migh t be sligh tly diff erent from a c ontinuous r un.The impac t of such sligh t mesh changes on the solution r esults will b e small, except f or c ases with a high degr ee of mesh dep endenc e; if y ou c annot use an HDF file f or such e xceptional c ases (f or e xample , when r unning 1281Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshesFluen t under ANSY S Workbench), it is r ecommended tha t you e valua te the or iginal mesh t o ensur e that it is suitable f or the pr oblem. 11.6.2.1.5. Laplacian Smo othing Metho d Laplacian smo othing is the most c ommonly used and the simplest mesh smo othing metho d.This metho d adjusts the lo cation of each mesh v ertex to the geometr ic center of its neighb oring v ertices. This metho d is c omputa tionally ine xpensiv e but it do es not guar antee an impr ovemen t on mesh qualit y, sinc e repositioning a v ertex by Laplacian smo othing c an r esult in p oor qualit y elemen ts.To overcome this pr oblem, ANSY S Fluen t only r elocates the v ertex to the geometr ic center of its neighb oring v ertices if and only if ther e is an impr ovemen t in the mesh qualit y (tha t is, the sk ewness has b een impr oved). This impr oved Laplacian smo othing c an b e enabled on def orming b oundar ies only (tha t is, the z one with tr iangular elemen ts in 3D and z ones with linear elemen ts in 2D). The c omputa tion of the no de positions w orks as f ollows: (11.13) wher e is the a veraged no de p osition of no de at iteration , is the no de p osition of neighb or no de of at iteration , and is the numb er no des neighb oring no de .The new no de position is then c omput ed as f ollows: (11.14) wher e is the Laplac e no de r elaxa tion fac tor. This up date only happ ens if the maximum sk ewness of all fac es adjac ent to is impr oved in compar ison t o . For details on applying Laplacian smo othing t o either a c ell z one (with 2.5D r emeshing) or a fac e zone , see Smoothing M etho ds (p.1268 ) or Deforming M otion (p.1354 ), respectively. 11.6.2.1.6. Boundar y Layer Smo othing Metho d The b oundar y layer smo othing metho d is used t o def orm the b oundar y layer mesh dur ing a mo ving- deforming mesh simula tion. For c ases tha t apply mesh motion (either Rigid B ody or User-D efined ) to a fac e zone with adjac ent boundar y layers, the b oundar y layers c an b e made t o def orm acc ordingly by enabling Deform A djac ent Boundar y Layer with Z one for the fac e zone in the Dynamic M esh Zones D ialog Box (p.3587 ).With b oundar y layer smo othing enabled , the no dal c oordina tes of each cell in the b oundar y layer zone ar e up dated with the same displac emen t vector as the c orresponding nodes on the under lying fac e zone .The b oundar y layer smo othing metho d can b e applied t o boundar y layer zones of all mesh t ypes (tha t is, wedges and he xahedr a in 3D , quadr ilaterals in 2D). Consider the e xample b elow, wher e a UDF of the f orm DEFINE_GRID_MOTION provides the moving-def orming mesh mo del with the lo cations of the no des lo cated on the c omplian t str ip on an idealiz ed air foil.The no de motion v aries sinusoidally in time and spac e (compar e Figur e 11.25: The Undef ormed M esh (p.1283 ) with Figur e 11.26: The D eformed M esh (p.1283 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1282Modeling F lows Using S liding and D ynamic M eshesFigur e 11.25: The U ndef ormed M esh Figur e 11.26: The D eformed M esh 1283Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshesAs a r esult of the b oundar y layer smo othing , the c ells adjac ent to the def orming w all ar e also de- formed in or der t o pr eser ve the qualit y of b oundar y layer zone . If you c ompar e Figur e 11.27: Zooming into the U ndef ormed C omplian t Strip (p.1284 ) with Figur e 11.28: Zooming in to the D eformed C omplian t Strip with B oundar y La yer S moothing A pplied (p.1285 ), you c an see ho w the b oundar y layer cells have been def ormed acc ording t o the motion of the no des on the c omplian t str ip. Figur e 11.27: Zooming in to the U ndef ormed C omplian t Strip Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1284Modeling F lows Using S liding and D ynamic M eshesFigur e 11.28: Zooming in to the D eformed C omplian t Strip with B oundar y Layer S moothing Applied Typic ally, the b oundar y layer smo othing metho d pr eser ves the heigh t of the b oundar y layer cells adjac ent to the def ormed fac e zone . However, not e tha t this appr oach is pr imar ily in tended f or transla tional motion. If the fac es under go substan tial r otation, the b oundar y layer cells ma y become skewed. See Smoothing M etho ds (p.1268 ) and Specifying B oundar y La yer D eformation S mooth- ing (p.1360 ) for details ab out enabling smo othing and defining a mo ving and def orming b oundar y layer, respectively. Note tha t boundar y layer smo othing is c ompa tible with spr ing-based smo othing only . It cannot b e used with diffusion-based smo othing or linear ly elastic solid smo othing . Also not e that the b oundar y layer smo othing metho d will w ork whether or not y ou ha ve segr egated the boundar y layer elemen ts in to a separ ate cell z one . 11.6.2.2. Dynamic L ayering In pr isma tic (he xahedr al and/or w edge) mesh z ones , you c an use d ynamic la yering t o add or r emo ve layers of c ells adjac ent to a mo ving b oundar y, based on the heigh t of the la yer adjac ent to the moving sur face.The d ynamic mesh mo del in ANSY S Fluen t allo ws you t o sp ecify an ideal la yer heigh t on each mo ving b oundar y.The la yer of c ells adjac ent to the mo ving b oundar y (la yer in Fig- ure 11.29: Dynamic La yering (p.1286 )) is split or mer ged with the la yer of c ells ne xt to it (la yer in Figur e 11.29: Dynamic La yering (p.1286 )) based on the heigh t ( ) of the c ells in la yer . 1285Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshesFigur e 11.29: Dynamic L ayering If the c ells in la yer are expanding , the c ell heigh ts ar e allo wed t o incr ease un til (11.15) wher e is the minimum c ell heigh t of c ell la yer , is the ideal c ell heigh t, and is the la yer split fac tor. Note tha t ANSY S Fluen t allo ws you t o define as either a c onstan t value or a v alue that varies as a func tion of time or cr ank angle .When the c ondition in Equa tion 11.15 (p.1286 ) is met , the c ells ar e split based on the sp ecified la yering option. This option c an b e heigh t based or r atio based . With the heigh t-based option, the c ells ar e split t o cr eate a la yer of c ells with c onstan t heigh t and a la yer of c ells of heigh t .With the r atio-based option the c ells ar e split such tha t, locally, the r atio of the new c ell heigh ts to old c ell heigh ts is e xactly everywher e.Figur e 11.30: Results of Splitting La yer with the H eigh t-Based Option (p.1286 ) and Figur e 11.31: Results of S plitting La yer with the R atio-B ased Option (p.1287 ) sho w the r esult of splitting a la yer of c ells ab ove a v alve geometr y using the heigh t-based and r atio-based option. Figur e 11.30: Results of S plitting L ayer with the H eigh t-Based Option Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1286Modeling F lows Using S liding and D ynamic M eshesFigur e 11.31: Results of S plitting L ayer with the R atio-B ased Option If the c ells in la yer are being c ompr essed , the y can b e compr essed un til (11.16) wher e is the la yer collapse fac tor.When this c ondition is met , the c ompr essed la yer of c ells is mer ged in to the la yer of c ells ab ove the c ompr essed la yer in Figur e 11.29: Dynamic La yering (p.1286 ); that is, the c ells in la yer are mer ged with those in la yer . To enable d ynamic la yering, enable the Layering option under Mesh M etho ds in the Dynamic M esh Task P age (p.3567 ) (Figur e 11.32: The La yering Tab in the M esh M etho d Settings D ialog Box (p.1288 )). The la yering c ontrol is sp ecified in the Layering tab , which c an b e displa yed b y click ing Settings .... 1287Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshesFigur e 11.32: The L ayering Tab in the M esh M etho d Settings D ialo g Box You c an c ontrol ho w a c ell la yer is split b y sp ecifying either Heigh t Based or Ratio B ased under Options . Note tha t for Heigh t Based , the heigh t of the c ells in a par ticular new la yer will b e constan t, but y ou c an cho ose t o ha ve this heigh t vary from la yer to layer as a func tion of time or cr ank angle when y ou sp ecify the Cell H eigh t in the Dynamic M esh Z ones dialo g box (see Specifying the M otion of D ynamic Z ones (p.1345 ) for fur ther details). The Split F actor and Collapse F actor ( in Equa tion 11.15 (p.1286 ) and in Equa tion 11.16 (p.1287 ), respectively) ar e the fac tors tha t det ermine when a la yer of c ells (he xahedr a or w edges in 3D , or quadr ilaterals in 2D) tha t is ne xt to a mo ving b oundar y is split or mer ged with the adjac ent cell la yer, respectively. 11.6.2.2.1. Applic abilit y of the D ynamic L ayering Metho d You c an use the d ynamic la yering metho d to split or mer ge c ells adjac ent to an y mo ving b oundar y provided the f ollowing c onditions ar e met: •All cells adjac ent to the mo ving fac e zone ar e either w edges or he xahedr a (quadr ilaterals in 2D) e ven though the c ell z one ma y contain mix ed c ell shap es. •The c ell la yers must b e complet ely b ounded b y one-sided fac e zones , except when sliding in terfaces ar e used (see Applic abilit y of the F ace Region R emeshing M etho d (p.1303 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1288Modeling F lows Using S liding and D ynamic M eshes•Note tha t you c annot use the d ynamic la yering metho d in c onjunc tion with adaption in almost all c ases . For mor e inf ormation on the a vailable adaption metho ds, see Hanging N ode A daption and Polyhedr al Unstr uctured M esh A daption in the Theor y Guide . If the mo ving b oundar y is an in ternal z one , cells on b oth sides (p ossibly with diff erent ideal c ell layer heigh ts) of the in ternal z one ar e consider ed f or d ynamic la yering. If you w ant to use d ynamic la yering on c ells adjac ent to a mo ving w all tha t do not span fr om boundar y to boundar y, you must separ ate those c ells tha t are involved in the d ynamic la yering and use the sliding in terfaces c apabilit y in ANSY S Fluen t to transition fr om the def orming c ells t o the adjac ent non-def orming c ells (see Figur e 11.33: Use of S liding In terfaces to Transition B etween A djac ent Cell Z ones and the D ynamic La yering C ell Z one (p.1289 )). For a mo ving in terior fac e, the z ones must be separ ated such tha t the y are either e xpanding or c ollapsing on the same side . No one z one c an consist of b oth e xpanding and c ollapsing la yers. Figur e 11.33: Use of S liding In terfaces t o Transition B etween A djac ent Cell Z ones and the Dynamic L ayering C ell Z one 11.6.2.3. Remeshing Metho ds When the b oundar y displac emen t is lar ge c ompar ed t o the lo cal cell siz es, the c ell qualit y can det eri- orate or the c ells c an b ecome degener ate if only mesh smo othing is used .This will in valida te the mesh (f or e xample , result in nega tive cell v olumes) and c onsequen tly, will lead t o convergenc e problems when the solution is up dated t o the ne xt time st ep. To cir cum vent this pr oblem, ANSY S Fluen t agglomer ates c ells tha t viola te the sk ewness or siz e cr iteria and lo cally r emeshes the agglomer ated c ells or fac es. If the new c ells or fac es sa tisfy the sk ewness criterion, the mesh is lo cally up dated with the new c ells (with the solution in terpolated fr om the old cells). Other wise , the new c ells ar e disc arded and the old c ells ar e retained . ANSY S Fluen t includes se veral remeshing metho ds tha t include lo cal cell r emeshing , zone r emeshing , local fac e remeshing (f or 3D flo ws only), face region r emeshing , CutCell z one r emeshing (f or 3D flo ws only), and 2.5D sur face remeshing (f or 3D flo ws only). The r emeshing metho ds ar e suitable f or par tic- ular k inds of c ell t ypes: 1289Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshes•The lo cal cell remeshing metho d only aff ects tr iangular and t etrahedr al cell types in the mesh (tha t is, in mixed c ell z ones the non-tr iangular/t etrahedr al cells ar e sk ipped). •The lo cal fac e remeshing metho d is a vailable in 3D only and c an r emesh t etrahedr al cells and w edge c ells in b oundar y layer meshes . •The z one r emeshing metho d replac es all c ell types with tr iangular t etrahedr al cells (in 2D and 3D domains , respectively), and c an r emesh and pr oduce wedge c ells in 3D b oundar y layer meshes . •The fac e region r emeshing metho d is applied t o triangular c ells in 2D , and t etrahedr al cells in 3D . In 3D domains , the fac e region r emeshing metho d can also r emesh and pr oduce wedge c ells in 3D b oundar y layer meshes . •The C utCell z one r emeshing metho d works for all c ell types. •The 2.5D r emeshing metho d only w orks on he xagonal meshes or w edge c ells e xtruded fr om tr iangular surface elemen ts. To enable r emeshing metho ds, enable the Remeshing option under Mesh M etho ds in the Dynamic Mesh Task P age (p.3567 ) (Figur e 11.13: The D ynamic M esh Task P age (p.1267 )). Click the Settings ... butt on t o op en the Mesh M etho d Settings dialo g box, wher e you c an sp ecify the r emeshing metho d and par amet ers in the Remeshing tab ( Figur e 11.34: The R emeshing Tab in the M esh M etho d Settings Dialog Box (p.1291 )). You c an view the vital sta tistics of y our mesh b y click ing the Mesh Sc ale Inf o... butt on a t the b ottom of the Mesh M etho d Settings D ialog Box (p.3570 ).This butt on op ens the Mesh Sc ale Inf o Dialog Box (p.3574 ), wher e you c an view the minimum and maximum length sc ale v alues , as w ell as the maximum c ell and fac e sk ewness v alues . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1290Modeling F lows Using S liding and D ynamic M eshesFigur e 11.34: The Remeshing Tab in the M esh M etho d Settings D ialo g Box 1291Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshesFigur e 11.35: The Remeshing Tab in the M esh M etho d Settings D ialo g Box Using the S izing Func tion Option 11.6.2.3.1. Local R emeshing Metho d Using the lo cal remeshing metho d (tha t is, local cell r emeshing , with or without lo cal fac e remeshing), ANSY S Fluen t mar ks c ells based on c ell sk ewness and minimum and maximum length sc ales as w ell as an optional sizing func tion. ANSY S Fluen t evalua tes each c ell and mar ks it f or remeshing if it meets one or mor e of the f ollowing criteria: •It has a sk ewness tha t is gr eater than a sp ecified maximum sk ewness . •It is smaller than a sp ecified minimum length sc ale. •It is lar ger than a sp ecified maximum length sc ale. •Its heigh t do es not meet the sp ecified length sc ale (a t mo ving fac e zones , for e xample , above a mo ving piston). If local remeshing is not able t o reduc e the maximum c ell sk ewness sufficien tly, then the c ell z one remeshing metho d is used t o aut oma tically r emesh all of the c ells in the c ell z one , as w ell as the faces of all adjac ent def orming d ynamic fac e zones (see Cell Z one R emeshing M etho d (p.1299 ) for details). The maximum allo wable c ell sk ewness is set t o be 0.98 b y default. The c ell z one r emeshing Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1292Modeling F lows Using S liding and D ynamic M eshesmetho d giv es the mesher mor e fle xibilit y to cr eate a new mesh of b etter qualit y than the lo cal cell remeshing metho d.The aut oma tic r emeshing of c ell z ones c an b e disabled using the f ollowing t ext command: define → dynamic-mesh → controls → remeshing-parameter → zone-remeshing 11.6.2.3.1.1. Local C ell R emeshing Metho d As pr eviously men tioned , in lo cal cell r emeshing , ANSY S Fluen t agglomer ates c ells based on sk ewness , size, and heigh t (adjac ent mo ving fac e zones) pr ior t o the mo vemen t of the b oundar y.The siz e cr i- teria ar e sp ecified with Minimum L ength Sc ale and Maximum L ength Sc ale. Cells with length scales b elow the minimum length sc ale and ab ove the maximum length sc ale ar e mar ked f or remeshing .The v alue of Maximum C ell S kewness indic ates the desir ed sk ewness of the mesh. By default , the Maximum C ell S kewness is set t o 0.9 f or 3D simula tions and 0.7 f or 2D simula tions . Cells with sk ewness ab ove the maximum sk ewness ar e mar ked f or remeshing . The mar king of c ells based on sk ewness is done a t every time st ep when the lo cal remeshing metho d is enabled . However, mar king based on siz e and heigh t is p erformed b etween the sp ecified Size Remeshing In terval sinc e the change in c ell siz e distr ibution is t ypic ally small o ver one time step. Note tha t you should edit the fields in the Paramet ers group b ox, as the initial v alues ar e unlik ely to pr oduce your desir ed out come . Clicking Default will define v alues tha t are based on y our par tic- ular mesh and tha t should r epresen t a r easonable star ting p oint, and y ou c an then adjust them as needed . After y ou click the Default butt on, it will then change t o be a Reset butt on, which c an b e used t o retur n to the pr ior v alues . By default , ANSY S Fluen t replac es the agglomer ated c ells only if the qualit y of the r emeshed c ells has impr oved. Note tha t you c annot use the lo cal cell r emeshing metho d in c onjunc tion with adaption. For mor e information on the a vailable adaption metho ds, see Hanging N ode A daption and Polyhedr al U nstr uc- tured M esh A daption in the Theor y Guide . 11.6.2.3.1.2. Local F ace Remeshing Metho d The lo cal fac e remeshing metho d only applies t o 3D geometr ies.You c an apply this metho d to the boundar ies of def orming or user-defined z one t ypes, so tha t ANSY S Fluen t will mar k fac es (and ad- jacent cells) based on the fac e sk ewness , and then r emesh them. Local fac e remeshing also allo ws the r emeshing of w edge c ells in b oundar y layers a t those b ound- aries.The det ection of b oundar y layers (as w ell as the w edge elemen t heigh t distr ibution and numb er of la yers) is aut oma tic and do es not r equir e your input. To apply lo cal fac e remeshing , perform the f ollowing st eps: 1.Enable the Local F ace option in the Remeshing tab of the Mesh M etho d Settings D ialog Box (p.3570 ), and set the Maximum F ace Skewness to an appr opriate global v alue . 2.For each def orming or user-defined b oundar y zone on which y ou w ant local fac e remeshing applied , enable the Local option in the Meshing Options tab of the Dynamic M esh Z ones D ialog Box (p.3587 ).You c an also r evise the Maximum S kewness in this tab if y ou don't w ant to use the global setting f or a par ticular z one . Note tha t for def orming z ones , the Remeshing option must be enabled—which is the default c ondition—in or der t o acc ess the Local option, and the 1293Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshesGlobal S ettings option must b e disabled t o revise the Maximum S kewness . For fur ther details on the z one setup , see Deforming M otion (p.1354 ) and/or User-D efined M otion (p.1359 ). 11.6.2.3.1.2.1. Applic abilit y of the L ocal F ace Remeshing Metho d When y ou enable lo cal fac e remeshing f or a b oundar y, the fac es c an b e remeshed only if the f ollowing conditions ar e met: •The fac es ar e triangular . •The agglomer ated fac es do not span multiple z ones or f eature edges . Note tha t you c annot use the lo cal fac e remeshing metho d in c onjunc tion with adaption. For mor e information on the a vailable adaption metho ds, see Hanging N ode A daption and Polyhedr al U nstr uc- tured M esh A daption in the Theor y Guide . 11.6.2.3.1.3. Local R emeshing B ased on S izing F unc tion Instead of mar king c ells based on minimum and maximum length sc ales , ANSY S Fluen t also mar ks cells based on the siz e distr ibution gener ated b y the sizing func tion if the Sizing F unc tion option is enabled . Cells c an b e mar ked using sizing func tions only with the f ollowing r emeshing metho ds: •local cell remeshing •2.5D sur face remeshing (as descr ibed in 2.5D Sur face Remeshing M etho d (p.1308 )) Figur e 11.37: Mesh a t the End of a D ynamic M esh S imula tion With S izing F unctions (p.1295 ) demon- strates the ad vantages of using sizing func tions f or lo cal remeshing . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1294Modeling F lows Using S liding and D ynamic M eshesFigur e 11.36: Mesh a t the E nd of a D ynamic M esh S imula tion Without S izing F unc tions Figur e 11.37: Mesh a t the E nd of a D ynamic M esh S imula tion With S izing F unc tions In det ermining the sizing func tion, ANSY S Fluen t draws a b ounding b ox around the z one tha t is appr oxima tely t wice the siz e of the z one , and lo cates the shor test f eature length within each fluid 1295Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M esheszone . ANSY S Fluen t then sub divides the b ounding b ox based on the shor test f eature length and the sizing func tion Resolution tha t you sp ecify .This allo ws ANSY S Fluen t to cr eate a back ground mesh. You c ontrol the r esolution of the back ground mesh and a back ground mesh is cr eated f or each fluid zone .The shor test f eature length is det ermined b y shr inking a sec ond b ox around the objec t, and then selec ting the shor test edge on tha t box.The sizing func tion is e valua ted a t the v ertex of each individual back ground mesh. Figur e 11.38: Sizing F unc tion D etermina tion a t Back ground M esh Vertex I As seen in Figur e 11.38: Sizing F unction D etermina tion a t Background M esh Vertex I (p.1296 ), the local value of the sizing func tion is defined b y (11.17) wher e is the distanc e from v ertex on the back ground mesh t o the c entroid of b oundar y cell and is the mesh siz e (length) of b oundar y cell . The sizing func tion is then smo othed using Laplacian smo othing . ANSY S Fluen t then in terpolates the v alue of the sizing func tion b y calcula ting the distanc e from a giv en c ell c entroid to the back ground mesh v ertices tha t sur round the c ell (see Figur e 11.39: Interpolating the Value of the Sizing F unction (p.1297 )).The in termedia te value of the sizing func tion at the c entroid is c omput ed from (11.18) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1296Modeling F lows Using S liding and D ynamic M eshesFigur e 11.39: Interpolating the Value of the S izing F unc tion Next, a single p oint is lo cated within the domain (see Figur e 11.40: Determining the N ormaliz ed Distanc e (p.1298 )) tha t has the lar gest distanc e to the near est b oundar y to it. The nor maliz ed distanc e for the giv en c entroid is giv en b y (11.19) 1297Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshesFigur e 11.40: Determining the N ormaliz ed D istanc e Using the par amet ers and (the sizing func tion Variation and the sizing func tion Rate, respect- ively), you c an wr ite the final v alue of the sizing func tion a t point as (11.20) wher e is the in termedia te value of the sizing func tion a t the c ell c entroid. Note tha t is the sizing func tion variation . Positiv e values mean tha t the c ell siz e incr eases as y ou move away from the b oundar y. Since the maximum v alue of is one , the maximum c ell siz e becomes (11.21) ther efore, is really a measur e of the maximum c ell siz e. The fac tor is c omput ed fr om (11.22) (11.23) You c an use sizing func tion Variation (or ) to control ho w lar ge or small an in terior c ell c an b e with r espect to its closest b oundar y cell. ranges fr om to , an value of 0.5 indic ates tha t the in terior c ell siz e can b e, at most , 1.5 the siz e of the closest b oundar y cell. Conversely , an value of indic ates tha t the c ell siz e in terior of the b oundar y can b e half of tha t at the closest boundar y cell. A v alue of 0 indic ates a c onstan t siz e distr ibution a way from the b oundar y. You c an use the sizing func tion Rate (or ) to control ho w rapidly the c ell siz e varies fr om the boundar y.The v alue of should b e sp ecified such tha t . A p ositiv e value indic ates a slo wer tr ansition fr om the b oundar y to the sp ecified sizing func tion Variation value . Conversely , Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1298Modeling F lows Using S liding and D ynamic M eshesa nega tive value indic ates a fast er tr ansition fr om the b oundar y to the sizing func tion Variation value . A v alue of 0 indic ates a linear v ariation of c ell siz e away from the b oundar y. You c an also c ontrol the Resolution of the sizing func tion. This det ermines the siz e of the back ground bins used t o evalua te the siz e distr ibution with r espect to the shor test f eature length of the cur rent mesh. By default , the sizing func tion Resolution is 3 in 2D pr oblems , and 1 in 3D pr oblems . Note tha t if y ou edit the Resolution ,Variation , and/or Rate, click ing Default will r etur n these fields to the default v alues based on the cur rent mesh. The Default butt on will then change t o be a Reset butt on, which c an b e used t o retur n to the pr ior v alues . In summar y, the sizing func tion is a distanc e-weigh ted a verage of all mesh siz es on all b oundar y faces (b oth sta tionar y and mo ving b oundar ies). The sizing func tion is based on the siz es of the boundar y cells, with the siz e comput ed fr om the c ell v olume b y assuming a p erfect (equila teral) triangle in 2D and a p erfect tetrahedr on in 3D .You c an c ontrol the siz e distr ibution b y sp ecifying the sizing func tion Variation and the sizing func tion Rate. If you ha ve enabled the Sizing F unc tion option, ANSY S Fluen t will agglomer ate a c ell if (11.24) wher e is a fac tor defined b y Equa tion 11.22 (p.1298 ) and Equa tion 11.23 (p.1298 ). Note tha t the sizing func tion is only used f or mar king c ells before remeshing .The sizing func tion is not used t o go vern the siz e of the c ell dur ing r emeshing . For st eady-sta te applic ations (see Steady-State Dynamic M esh A pplic ations (p.1370 )), you c an instr uct ANSY S Fluen t to perform a sec ond r ound of c ell mar king and agglomer ation af ter the b oundar y has moved, based on sk ewness cr iteria.The in tent is t o fur ther impr ove the mesh qualit y thr ough addi- tional lo cal remeshing .This optional f eature works in c onjunc tion with the Mesh M etho d Settings dialo g box (Figur e 11.34: The R emeshing Tab in the M esh M etho d Settings D ialog Box (p.1291 )), and operates acc ording t o the sk ewness par amet ers y ou set in this dialo g box.The sizing func tion paramet ers ar e not c onsider ed dur ing this additional r emeshing . Note tha t enabling this option will increase the time r equir ed t o up date the mesh dur ing the solution. Note If you w ant to emplo y additional lo cal remeshing , first mak e sur e tha t you ha ve enabled the Remeshing option in the Dynamic M esh Task P age (p.3567 ). To enable the additional r ound of lo cal remeshing , use the f ollowing t ext command: define → dynamic-mesh → controls → remeshing-parameter → remeshing-after- moving? 11.6.2.3.2. Cell Z one R emeshing Metho d The c ell z one r emeshing metho d allo ws for the r emeshing of the c omplet e cell z one , and pr ovides the option t o also r emesh the fac es of all adjac ent def orming d ynamic fac e zones .This r emeshing metho d is enabled b y default when lo cal cell r emeshing is enabled , and is p erformed aut oma tically if the lo cal cell r emeshing do es not pr oduce an acc eptable mesh (see Local Remeshing M etho d (p.1292 ) for the acc eptabilit y criteria). Cell z one r emeshing c an also b e manually in voked, using the f ollowing text command: 1299Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshesdefine → dynamic-mesh → actions → remesh-cell-zone The c ell z one r emeshing metho d is a vailable f or tr iangular c ells in 2D meshes and t etrahedr al cells in 3D meshes . For 3D meshes , the metho d also allo ws the r emeshing of w edge c ells in b oundar y layers.The det ection of the b oundar y layers (as w ell as the w edge elemen t heigh t distr ibution and numb er of la yers) is aut oma tically p erformed b y default , and allo ws for diff erent layer par amet ers on each b oundar y zone .You c an manually sp ecify the par amet ers b y en tering nonz ero values f or first heigh t, growth r ate, and numb er of la yers via the t ext commands a vailable in the define/dynamic-mesh/controls/remeshing-parameters/prism-layer-parameters menu , although gener ally it is not nec essar y to do this .When y ou en ter them manually , the boundar y layer par amet ers ar e global: the y apply t o every pr ism la yer det ected in the r emeshing zone . Note tha t it is nec essar y to enable the d ynamic mesh mo del and the r emeshing metho d in or der t o attain acc ess t o the pr ism la yer controls, even if the c ell z one is r emeshed manually and not as par t of a d ynamic mesh up date. 11.6.2.3.2.1. Limitations of the C ell Z one R emeshing Metho d Zone r emeshing has the f ollowing limita tions: •Only tr iangular , tetrahedr al, and w edge c ell types (when the w edge c ells ar e par t of a 3D b oundar y layer mesh) ar e remeshed . •Zones with hanging no des c annot b e remeshed . 11.6.2.3.3. Face Region R emeshing Metho d The fac e region r emeshing metho d allo ws for the r emeshing of those tr iangular fac es (in 3D meshes) and linear fac es (in 2D meshes) tha t are on a def orming fac e zone and adjac ent to a mo ving fac e zone (see la yer j in Figur e 11.41: Expanding C ylinder B efore Region F ace Remeshing (p.1301 )). ANSY S Fluen t mar ks the fac es based on minimum and maximum length sc ales , and then r emeshes the fac es and the asso ciated c ells t o pr oduce a v ery regular mesh on the def orming b oundar y. Although primar ily designed f or in-c ylinder t ype configur ations , wher e the r emeshing r egion is lo cated wher e cylinder w alls meet the mo ving pist on, face region r emeshing c an b e used f or all applic ations wher e a mo ving d ynamic z one abuts def orming d ynamic fac e zones . For 3D simula tions , ANSY S Fluen t allo ws fac e region r emeshing with symmetr ic boundar y conditions and acr oss multiple fac e zones .The r emeshing c an pr eser ve features not only b etween the diff erent deforming fac e zones , but also within a fac e zone . For mor e inf ormation on f eature pr eser vation, see Feature Detection (p.1313 ). ANSY S Fluen t also allo ws fac e region r emeshing of t etrahedr al cell zones tha t contain w edge c ells in b oundar y layers, as descr ibed in the sec tion tha t follows. To begin mar king the fac es for fac e region r emeshing , ANSY S Fluen t iden tifies the no des a t the in- tersec tion of a mo ving d ynamic z one and the adjac ent def orming z ones . ANSY S Fluen t then analyz es the heigh t of the fac es on the def orming z ones tha t are in the r ange of the iden tified no des, and then r emeshes the fac es dep ending on the sp ecified maximum or minimum length sc ale. Consider the simple t etrahedr al mesh of a c ylinder tha t has a mo ving end w all (see Figur e 11.41: Ex- panding C ylinder B efore Region F ace Remeshing (p.1301 )).The fac es tha t are subjec t to remeshing are in la yer j of the side w all. If the fac es in la yer j ar e expanding , the e xpansion c ontinues un til the heigh t h r eaches the maximum length sc ale, and then the la yer is r emeshed t o form 2 la yers of elemen ts (see Figur e 11.42: Expanding C ylinder A fter R egion F ace Remeshing (p.1301 )). Conversely , if the fac es of la yer j ar e contracting , the c ontraction c ontinues un til h r eaches the minimum length Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1300Modeling F lows Using S liding and D ynamic M eshesscale, and then la yer j and the neighb oring la yer of fac es (la yer i) on the def orming z one ar e remeshed to form a single la yer. Figur e 11.41: Expanding C ylinder B efore Region F ace Remeshing Figur e 11.42: Expanding C ylinder A fter Region F ace Remeshing 11.6.2.3.3.1. Face Region R emeshing with Wedge C ells in P rism L ayers In 3D simula tions , the fac e region r emeshing metho d can b e applied on meshes tha t ha ve wedge cells along the def orming fac e zones .When r emeshing the fac es on the def orming fac e zones , the asso ciated w edge c ells ar e remeshed as w ell.The la yer par amet ers ar e based on the e xisting mesh by default; you ha ve the option of manually setting these par amet ers, as descr ibed la ter in this section. 1301Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshesIf the motion of the fac e zone is lar ge c ompar ed t o the heigh t of the adjac ent def orming fac e zones , it is r ecommended tha t you dec omp ose the mesh v olume in such a w ay as t o cr eate a d ynamic c ell zone tha t mo ves as a r igid b ody in b etween the mo ving fac e zone and the def orming d ynamic c ell zone on which fac e region r emeshing is applied . Consider Figur e 11.43: Volume D ecomp osition f or Prism La yers (p.1302 ), which displa ys only half of an in-c ylinder mesh. The r igidly mo ving c ell z one encapsula tes the pr ism la yers on the mo ving pist on so tha t the la yers ar e not r emeshed , and ther efore the r isk of gener ating degener ate cells dur ing the mesh motion up date is r educ ed. Figur e 11.43: Volume D ecomp osition f or P rism L ayers It is pr eferable (and e ven manda tory, if the mesh is a half mo del with a symmetr y plane) t o dec omp ose the v olume such tha t the “corner” region of the pr ism la yers (sho wn in the pr evious figur e) e xists entirely within the r igidly mo ving z one .This allo ws for the lar gest def ormations without r isking de- gener ate elemen ts, because the pr ism nor mals of the r emeshed c ells ar e unif ormly p erpendicular to the fac es under going r emeshing . If the r ange of motion do es not allo w you t o enc apsula te the en tire corner r egion of the pr ism la yers in a r igidly mo ving z one , it is r ecommended tha t you enc apsula te the “base ” of the pr ism la yers (sho wn in Figur e 11.44: Volume D ecomp osition f or the B ase of the P rism La yers (p.1303 )) and mo ve these c ells with a r igid b ody motion. Although this is less ideal than enc apsula ting the c orner r egion, it do es reduc e the r isk of degener ate mesh elemen ts. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1302Modeling F lows Using S liding and D ynamic M eshesFigur e 11.44: Volume D ecomp osition f or the B ase of the P rism L ayers For pist on-t ype applic ations tha t contain pr ism la yers, a reasonable r ule of thumb is tha t you should decomp ose the mesh v olume if the pist on motion is mor e than half the c ylinder heigh t. If you decide not t o dec omp ose the v olume a t all, you must a t the v ery least enable the Deform A djac ent Boundar y Layer with Z one option in the Meshing Options tab of the Dynamic M esh Z one dialo g box when setting up the mo ving fac e zone (see Rigid B ody Motion (p.1349 ) for details). In an y case, it is r ecommended tha t you alw ays pr eview the mesh motion o ver the c omplet e simula tion time , to mak e sur e tha t you will ha ve a v alid mesh a t each time st ep. The pr ism la yer par amet ers (tha t is, elemen t heigh t, growth r ate, and numb er of la yers) ar e extracted automa tically fr om the mesh and do not gener ally r equir e your input. To pr event the pr ism par amet ers from dr ifting due t o repeated r emeshing , the pr ism par amet ers f or first heigh t, growth r ate, and numb er of la yers c an b e en tered manually , using the t ext commands a vailable in the define/dy- namic-mesh/controls/remeshing-parameters/prism-layer-parameters menu . 11.6.2.3.3.2. Applic abilit y of the F ace Region R emeshing Metho d Note the f ollowing limita tions asso ciated with fac e region r emeshing: 1303Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshes•You c an use the fac e region r emeshing metho d only in c ell z ones tha t contain tr iangular c ells (in 2D) or tetrahedr al cells, with or without pr ism la yers (in 3D). For 3D meshes , the fac es on the def orming boundar ies tha t border the mo ving fac e must all b e triangular . •The fac e region r emeshing metho d is not c ompa tible with diffusion-based smo othing or linear ly elastic solid smo othing . •You c annot use the fac e region r emeshing metho d in c onjunc tion with adaption. For mor e inf ormation on the a vailable adaption metho ds, see Hanging N ode A daption and Polyhedr al U nstr uctured M esh Adaption in the Theor y Guide . 11.6.2.3.4. CutC ell Z one R emeshing Metho d The C utCell z one r emeshing metho d is a vailable t o remesh a c omplet e cell z one (including all boundar y zones of the r emeshed c ell z one). This metho d is a vailable f or 3D simula tions only .The existing v olume mesh is r eplac ed b y a pr edominan tly C artesian mesh. Infla tion la yers c an b e added as an option. When used as par t of a tr ansien t simula tion, the r emeshing o ccurs a t predefined in tervals and whene ver the mesh qualit y in the c ell z one is deemed p oor. Examples of meshes b efore and after C utCell z one r emeshing ar e sho wn in Figur e 11.45: Unstr uctured Tetrahedr al M esh B efore CutCell Zone R emeshing (p.1304 ) and Figur e 11.46: Mesh A fter C utCell Z one R emeshing (p.1305 ), respectively. Figur e 11.47: CutCell Z one R emeshing With Infla tion La yers (p.1305 ) sho ws a cut thr ough a C utCell mesh with infla tion la yers. Figur e 11.45: Unstr uctured Tetrahedr al M esh B efore CutC ell Z one Remeshing Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1304Modeling F lows Using S liding and D ynamic M eshesFigur e 11.46: Mesh A fter C utC ell Z one Remeshing Figur e 11.47: CutC ell Z one Remeshing With Infla tion L ayers During C utCell z one r emeshing , a unif orm C artesian gr id is lo cally r efined using siz e func tions , in order t o resolv e the initial mesh with sufficien t accur acy.The r esulting mesh c onsists mostly of hexahedr al elemen ts, which r educ es the c ell c oun t compar ed t o unstr uctured t etrahedr al meshing . Additional elemen t types ar e used near the b oundar ies t o closely r esolv e comple x shap es.The remeshing tak es plac e at regular in tervals, or whene ver the mesh qualit y det eriorates due t o mesh motion. The C utCell z one r emeshing metho d not only r eplac es the v olume mesh, it also r eplac es the c omplet e surface mesh of the r emeshed c ell z one . Consequen tly, this metho d can only b e used t o remesh c ell 1305Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M esheszones tha t are either stand-alone z ones or ar e only c onnec ted t o other c ell z ones thr ough non- conformal in terfaces. If infla tion la yers ar e added t o a C utCell mesh, the infla tion la yers ar e gr own from the r emeshed sur face mesh, and the C utCell mesh is mor phed such tha t it smo othly ma tches the c ap sur faces of the infla tion la yers. The CutC ell Z one remeshing metho d option is a vailable in the Remeshing M etho ds group b ox. Note tha t the CutC ell Z one remeshing metho d do es not use an y of the par amet ers sp ecified in the Mesh M etho d Settings dialo g box.The par amet ers used t o control CutC ell Z one remeshing ar e specified in the Dynamic M esh Z ones dialo g box when setting up the z one and b oundar ies. For mor e inf ormation ab out C utCell meshes , see Gener ating the C utCell M esh (p.433) in the F luen t Meshing sec tion of the U ser’s Guide . 11.6.2.3.4.1. Applic abilit y of the C utC ell Z one R emeshing Metho d The C utCell z one r emeshing metho d can b e applied t o cell z ones , with the f ollowing limita tions: •The c ase must b e 3D . •The c ell z one c annot b e conformally c onnec ted t o other c ell z ones; tha t is, a CutCell z one must b e a stand-alone c ell z one , or c an only b e connec ted t o another z one thr ough a non-c onformal in terface. In the la tter case, the non-c onformal in terface is clear ed b efore the r emeshing and aut oma tically r ecreated after the r emeshing . Note tha t the C utCell z one r emeshing metho d can b e applied t o cell z ones tha t contain adapt ed cells. In par allel, all c ells of the r emeshed z one will b e aut oma tically migr ated t o and r emeshed on a single CPU. Consequen tly, the machine memor y will limit the siz e of the z one tha t can b e remeshed .The mesh is aut oma tically r epar titioned af ter the r emeshing . In addition t o the limita tions list ed pr eviously , you should also not e the f ollowing with r egar d to CutCell z one r emeshing: •Internal c oupled w alls, such as baffles , are disc arded dur ing the r emeshing .The metho d is designed to pr imar ily remesh c ell z ones with a single in terior z one . •Interior jump b oundar y condition z ones (f or e xample , fans , porous jumps), are disc arded dur ing the remeshing . •Conformal p eriodic b oundar y conditions ar e not main tained af ter the r emeshing . Any existing conformal p eriodic b oundar ies on the z one b eing r emeshed should slit and r eplac ed with non- conformal p eriodic b oundar ies. •If the z one b eing r emeshed c ontains multiple in terior z ones pr ior t o the r emeshing , all in terior z ones will b e collec ted in to a single in terior z one dur ing the C utCell z one r emeshing . 11.6.2.3.4.2. Using the C utC ell Z one R emeshing Metho d In or der t o apply C utCell z one r emeshing t o a c ell z one , begin b y enabling the CutC ell Z one option in the Remeshing M etho ds group b ox in the Remeshing tab of the Mesh M etho d Settings dialo g box (see Figur e 11.34: The R emeshing Tab in the M esh M etho d Settings D ialog Box (p.1291 )). Next, use the Dynamic M esh Z ones dialo g box to cr eate a def orming d ynamic z one f or the c ell z one (see Deforming M otion (p.1354 )).Then enable CutC ell in the Remeshing Options group b ox and en ter the r elevant remeshing par amet ers, including: the maximum mesh siz e for the C artesian c ells; the Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1306Modeling F lows Using S liding and D ynamic M eshesglobal siz e func tion gr owth r ate; the minimum or thogonal qualit y and r emeshing in terval to control the r emeshing fr equenc y; and the optional global infla tion la yer settings . ANSY S Fluen t allo ws you t o sp ecify either a sof t or a mesh-based siz e func tion t o control ho w the Cartesian mesh incr eases in siz e from the b oundar y toward the in terior of the c ell z one . For the sof t size func tion, you sp ecify a maximum mesh siz e for each b oundar y zone of the C utCell c ell z one . When y ou use the mesh-based siz e func tion, ANSY S Fluen t analyz es the e xisting mesh t o evalua te the nec essar y mesh r efinemen t at the b oundar y. See st ep 4 of Stationar y Zones (p.1346 ) for mor e in- formation ab out these siz e func tions .You ha ve control o ver the siz e func tion t ypes and par amet ers by defining the b oundar y zones as d ynamic z ones . If no b oundar y zone adjac ent to the C utCell z one is defined as a d ynamic z one , ANSY S Fluen t will aut oma tically apply mesh-based siz e func tions t o each C utCell b oundar y zone and use the global gr owth r ate en tered f or the c ell z one t o control the remeshing . Note tha t the siz e func tions used b y the C utCell z one r emeshing metho d ar e unr elated t o the sizing func tion used f or lo cal cell r emeshing (as descr ibed in Local Remeshing B ased on S izing F unc- tion (p.1294 )). ANSY S Fluen t allo ws you t o add infla tion la yers t o a C utCell mesh in or der t o better resolv e wall- bounded flo w features. After enabling Infla tion L ayers under the CutC ell Z one P aramet ers for the CutCell c ell z one , you c an sp ecify the global infla tion par amet ers in the Infla tion S ettings dialo g box.There ar e two types of infla tion la yers a vailable: a constan t type, wher e you c an sp ecify the constan t heigh t of the first la yer; and an asp ect-ratio type, wher e the first la yer heigh t is lo cally evalua ted based on the sp ecified asp ect ratio.The la tter is r ecommended and used b y default sinc e it is mor e robust and gener ally pr oduces higher qualit y CutCell meshes . By default , the infla tion settings sp ecified apply t o every boundar y of the c ell z one . If you w ould lik e to sp ecify diff erent in- flation settings f or diff erent boundar ies, you c an define these b oundar ies as d ynamic z ones and enable Zonal Infla tion L ayer C ontrol. Note tha t the Numb er of L ayers, other than 0, has t o be the same on all b oundar y zones . If diff erent numb ers of la yers ar e sp ecified on diff erent boundar ies, ANSY S Fluen t will only infla te up t o the lar gest c ommon numb er sp ecified . By setting the numb er of la yers on a b oundar y zone t o 0, you c an lo cally suppr ess the gr owth of infla tion la yers, however, note tha t the tr ansition is handled b y stair st epping and adding w edge elemen ts, which t ends t o gener ate sk ewed elemen ts for small la yer elemen t heigh ts. The c ells tha t contain hanging no des / edges as a r esult of the C utCell z one r emeshing ar e aut oma t- ically c onverted t o polyhedr al cells. See Limita tions (p.732) for details ab out limita tions asso ciated with p olyhedr al cells. It is r ecommended tha t you first manually apply the C utCell z one r emeshing metho d (as descr ibed in the sec tion tha t follows) and insp ect the mesh b efore using the metho d as par t of a tr ansien t simula tion, as this allo ws you t o evalua te if y our r emeshing par amet ers ar e suitable b efore running a calcula tion tha t is c omputa tionally e xpensiv e. 11.6.2.3.4.3. Appl ying the C utC ell Z one R emeshing Metho d M anuall y Although the C utCell z one r emeshing metho d is pr imar ily in tended as an aut oma tic r emeshing metho d dur ing d ynamic mesh up dates, you c an also manually cr eate a C utCell mesh (tha t is, you can r emesh without r unning a c alcula tion) b y using the f ollowing t ext command: define → dynamic-mesh → actions → remesh-cell-zone-cutcell You will b e pr ompt ed t o en ter the global par amet ers f or the C utCell z one r emeshing . If no d ynamic zones ar e set up in y our c ase, ANSY S Fluen t will use the global par amet ers y ou en ter and apply mesh-based siz e func tions t o each b oundar y of the C utCell z one . If the c ase is set up as a d ynamic 1307Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshesmesh c ase, manual r emeshing will use the inf ormation sp ecified on each C utCell b oundar y zone , including the z onal infla tion la yer settings . During manual C utCell z one r emeshing , the global paramet ers ar e tak en fr om the t ext interface input , and the global par amet ers sp ecified on the CutCell c ell z one ar e ignor ed. When e xecuting manual r emeshing thr ough the remesh-cell-zone-cutcell text command , you will b e pr ompt ed t o sp ecify whether t opology warnings should b e ignor ed. If you do not ignor e the t opology warnings , ANSY S Fluen t will analyz e the z one b eing r emeshed and r eport an y interior face zones tha t will get disc arded dur ing the r emeshing . If the z one b eing r emeshed has p eriodic boundar y zones , you will also b e pr ompt ed t o either ab ort the r emeshing pr ocess or slit the p eriodics in or der t o pr oceed. You will also b e pr ompt ed t o sp ecify whether the c ells tha t contain hanging no des / edges as a result of the C utCell z one r emeshing should b e converted t o polyhedr al cells. See Limita tions (p.732) for details ab out limita tions asso ciated with p olyhedr al cells. By default , all hanging no de c ells ar e converted t o polyhedr al cells. 11.6.2.3.5. 2.5D S urface Remeshing Metho d The 2.5D sur face remeshing metho d only applies t o extruded 3D geometr ies and is similar t o lo cal remeshing in t wo dimensions on a tr iangular sur face mesh (not a mix ed z one). Faces on a def orming boundar y are mar ked f or remeshing based on fac e sk ewness , minimum and maximum length sc ale; the 2.5D r emeshing metho d also giv es y ou the option of mar king c ells using sizing func tions , as descr ibed in Local Remeshing B ased on S izing F unction (p.1294 ). Figur e 11.48: Close-U p of 2.5D E xtruded F low M eter P ump G eometr y Before Remeshing and Laplacian S moothing Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1308Modeling F lows Using S liding and D ynamic M eshesFigur e 11.49: Close-U p of 2.5D E xtruded F low M eter P ump G eometr y After Remeshing and Laplacian S moothing 11.6.2.3.5.1. Applic abilit y of the 2.5D S urface Remeshing Metho d The f ollowing applies t o the 2.5D sur face remeshing metho d: •Triangular fac es get r emeshed based on mar king. •Extruded w edges get r emeshed based on the r emeshing of the tr iangular fac e. Only e xtruded r egions get r emeshed , not mix ed r egions . •The 2.5D r emeshing metho d do es not supp ort remeshing or mo ving no des on the p erimet er of the e x- truded z one(s). •Note tha t you c annot use the 2.5D sur face remeshing metho d in c onjunc tion with adaption. For mor e information on the a vailable adaption metho ds, see Hanging N ode A daption and Polyhedr al U nstr uctured Mesh A daption in the Theor y Guide . •The e xtrusion must b e along a str aigh t line nor mal t o the def orming z one and the cr oss-sec tion of the extruded/c oopered mesh must b e constan t along the e xtrusion dir ection. For mor e inf ormation ab out the 2.5D mo del, see Using the 2.5D M odel (p.1309 ). •Periodics ar e not supp orted a t the e xtruded z ones . 11.6.2.3.5.2. Using the 2.5D Mo del For 3D simula tions only , you c an selec t the 2.5D mo del under the Remeshing tab in the Mesh Metho d Settings D ialog Box (p.3570 ).This mo del allo ws for a sp ecific subset of r emeshing t echniques . 1309Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshesThe 2.5D mesh essen tially is a 2D tr iangular mesh which is e xpanded , or e xtruded , along the nor mal axis of the sp ecific d ynamic z one tha t you ar e in terested in mo deling .The tr iangular sur face mesh is remeshed and smo othed on one side , and the changes ar e then e xtruded t o the opp osite side . Rigid b ody motion is applied t o the mo ving fac e zones , while the tr iangular e xtrusion sur face is as- signed t o a def orming z one with r emeshing and smo othing enabled .The opp osite side of the tr ian- gular mesh is assigned t o be a def orming z one as w ell, with only smo othing enabled , as in Fig- ure 11.51: 2.5D Ex truded G ear P ump G eometr y (p.1311 ). Figur e 11.50: The Remeshing Tab f or the 2.5D M odel For mor e inf ormation on setting smo othing and r emeshing par amet ers, see Dynamic M esh U pdate Metho ds (p.1267 ). The 2.5D mo del only applies t o mappable (tha t is, extrudable) mesh geometr ies such as pumps , as in Figur e 11.51: 2.5D Ex truded G ear P ump G eometr y (p.1311 ). Only the asp ects of the geometr y tha t represen t the “moving par ts” must b e extruded in the mesh. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1310Modeling F lows Using S liding and D ynamic M eshesFigur e 11.51: 2.5D E xtruded G ear P ump G eometr y Imp ortant You must only apply smo othing t o the opp osite side of the e xtruded mesh, sinc e ANSY S Fluen t requir es the geometr y inf ormation f or the d ynamic z one . ANSY S Fluen t projec ts the no des back t o its geometr y after the e xtrusion. Without this geometr y inf ormation, the d ynamic z ones t ends t o lose its in tegrity. Imp ortant In par allel, a par tition metho d tha t par titions p erpendicular t o the e xtrusion sur face should be used . For e xample , if the nor mal of the e xtrusion sur face points in the X-dir ection then Cartesian-Y or C artesian-Z w ould b e the p erfect par tition metho ds. The 2.5D mo del is used in c ombina tion with a DEFINE_GRID_MOTION UDF . (See Hooking DEFINE_GRID_MOTION UDFs in the Fluen t Customiza tion M anual for inf ormation ab out ho oking this UDF .) This UDF is asso ciated with the e xtrusion sur face tha t is adjac ent to the c ell z one , in tur n applying the same def ormation t o the en tire cell z one .This appr oach is par ticular ly useful when mo deling gear pumps tha t are pr edominan tly e xtruded he xahedr al meshes . For mor e inf ormation ab out this UDF , contact your supp ort engineer . 1311Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshes11.6.2.4. Volume Mesh Up dat e Procedur e The v olume mesh is up dated aut oma tically based on the metho ds descr ibed in Dynamic M esh U pdate Metho ds (p.1267 ). ANSY S Fluen t decides which metho d to use f or a par ticular z one based on which model is enabled and the shap e of the c ells in the z one . For e xample , if the b oundar ies of a t etrahedr al cell z one ar e mo ving , and unless the z one has b een set up f or C utCell z one r emeshing , the mesh smo othing and lo cal remeshing metho ds will b e used t o up date the v olume mesh in this z one . If the zone c onsists of pr isma tic (he xahedr al and/or w edge) c ells, then the d ynamic la yer metho d will b e used t o det ermine wher e and when t o inser t and r emo ve cell la yers. On e xtruded pr ism z ones , the 2.5D sur face meshing metho d will b e used . Depending on which mo del is enabled , ANSY S Fluen t aut oma tically det ermines which metho d to use by visiting the adjac ent cell z ones and setting appr opriate flags f or the v olume mesh up date metho ds to be used . If you sp ecify the motion f or a c ell z one , ANSY S Fluen t will visit all of the neighb oring c ell zones and set the flags appr opriately. If you sp ecify the motion of a b oundar y zone , ANSY S Fluen t will analyz e only the adjac ent cell z ones . If a c ell z one do es not ha ve an y mo ving b oundar ies, then no volume mesh up date metho d will b e applied t o the z one . Imp ortant Note tha t as a r esult of the r emeshing pr ocedur es, updated meshes ma y be sligh tly diff erent when d ynamic meshes ar e used in par allel ANSY S Fluen t, and ther efore very small diff er- ences ma y ar ise in the solutions . Imp ortant Note tha t if y our d ynamic mesh mo del c onsists of numer ous shell c onduc tion z ones , the mesh up date ma y be very time c onsuming b ecause all shells ar e delet ed and r ecreated during the mesh up date. 11.6.2.5. Transient C onsider ations for R emeshing and L ayering The sec ond or der in time tr ansien t formula tion c an b e used with r emeshing , layering, and smo othing cases . In such c ases , sec ond or der in time accur acy is pr eser ved dur ing la yering e vents and/or mesh smo othing . However, dur ing r emeshing e vents, the time ad vancemen t accur acy reverts to first or der. Therefore, it is r ecommended tha t you only use sec ond or der in time f or c ases with v ery low remeshing fr equenc y, tha t is, for c ases wher e remeshing o ccurs e very se veral timest eps or mor e. If remeshing o ccurs e very timest ep, the metho d reduc es to a first or der f ormula tion. For c ases tha t need v ery frequen t remeshing , it is r ecommended tha t you r etain the first or der in time f ormula tion. For details , see Dynamic M esh Theor y in the Fluent Theor y Guide . The swit ch t o first or der happ ens aut oma tically when the solv er det ects a t opology change as a r esult of remeshing within a timest ep.You will not see a change in the user in terface, however y ou c an monit or the swit ch b etween first and sec ond or der in time b y using the f ollowing t ext command t o enable the v erbosity with d ynamic meshes: define → dynamic-mesh → transient-settings → verbosity Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1312Modeling F lows Using S liding and D ynamic M eshesA message sho wing the ac tive time f ormula tion will pr int to the c onsole when v erbosity is set t o 1. Note For c ases with sec ond or der in time with d ynamic mesh enabled , any mesh sw apping and manual mesh manipula tion will tr igger a swit ch t o first or der in time . 11.6.3. Feature Detection The r emeshing and/or smo othing of b oundar y zones ma y result in the chamf ering of c orners wher e cell fac es meet. However, ther e ma y be some c orners (iden tified b y a par ticular angular r ange) tha t are imp ortant for y our flo w, and tha t you do not w ant chamf ered. For 3D c ases , you c an sp ecify tha t ANSY S Fluen t det ects such c orners (or "f eatures") and pr eser ves them. Such f eatures ma y be at the junc ture of diff erent boundar y zones , or the y ma y be on a single non-planar b oundar y zone . In the Geometr y D efinition tab of the Dynamic M esh Z ones D ialog Box (p.3587 ) for an y Definition type, you c an indic ate whether y ou w ant to pr eser ve features b y enabling Feature D etection under Feature Options and sp ecifying a thr eshold v alue f or the Feature Angle . A v alue of 180 degr ees (the default) f or the Feature Angle means tha t none of the c orners must b e pr eser ved, wher eas a v alue of 0 means tha t all of the c orners must b e pr eser ved. To illustr ate the setting of the Feature Angle , see Figur e 11.52: Cross S ection of a 3D C orner (p.1313 ). If you set the Feature Angle to 40 degr ees, this c orner w ould b e guar anteed t o be pr eser ved. If you set it t o 50 degr ees, this c orner c ould b e chamf ered. Figur e 11.52: Cross S ection of a 3D C orner 11.6.3.1. Applic abilit y of F eatur e Detection The f ollowing it ems ar e applic able f or use with f eature det ection: •Feature remeshing is only p ossible with fac e region r emeshing . •Features ar e pr eser ved b y local fac e remeshing , tha t is, ther e is no lo cal fac e remeshing acr oss f eatures. •Smoothing metho ds pr eser ve features, tha t is, nodes a t feature edges ar e not allo wed t o be smo othed . 11.6.4. In-C ylinder S ettings You c an enable the In-C ylinder option in the Dynamic M esh Task P age (p.3567 ) (Figur e 11.13: The D y- namic M esh Task P age (p.1267 )) for tr ansien t problems .Then click the Settings ... butt on in the Options group b ox to op en the Options D ialog Box (p.3575 ). Click the In-C ylinder tab and sp ecify the Crank Shaft Speed , the Starting C rank A ngle , and the Crank P eriod, which ar e used t o convert between flow time and cr ank angle .You must also sp ecify the time st ep t o use f or ad vancing the solution in 1313Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshesterms of cr ank angle in Crank A ngle S tep S ize. By default , ANSY S Fluen t assumes a Crank A ngle S tep Size of 0.5 degr ees. Figur e 11.53: The In-C ylinder Tab of the Options D ialo g Box ANSY S Fluen t provides a built-in func tion tha t can define the lo cation of the pist on as a func tion of crank angle .This func tion is named **pist on-full** , and is selec ted fr om the Motion/UDF P rofile drop-do wn list in the Dynamic M esh Z ones dialo g box as par t of r igid b ody motion (see Rigid B ody Motion (p.1349 ) for details). If you plan t o sp ecify the pist on motion using this func tion, you must sp ecify the Crank R adius (tha t is, the distanc e between the cr ank c enter and the c enter of the cr ank pin) and the Connec ting Ro d Length .You also ha ve the option of en tering a v alue f or the Piston P in O ffset for c ases when the pist on pin is off set p erpendicular ly fr om the plane defined b y the cr ank shaf t axis and the dir ection of motion of the pist on.The sign of this off set c an b e positiv e or nega tive, and is determined based on the geometr y and the dir ection of r otation of the cr ank shaf t (as sho wn in Fig- ure 11.54: Determining the S ign of the P iston P in O ffset (p.1315 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1314Modeling F lows Using S liding and D ynamic M eshesFigur e 11.54: Determining the S ign of the P iston P in O ffset When the **pist on-full** func tion is used , the pist on lo cation is c alcula ted acc ording t o the f ollowing equa tion: (11.25) wher e is the pist on lo cation, the cr ank r adius , is the c onnec ting r od length, is the pist on pin off set, and is the cur rent crank angle . The pist on lo cation is alw ays 0 a t top-dead-c enter (TDC), tha t is, when the cr ank pin is p erfectly aligned b etween the pist on pin and the c enter of r otation of the cr ank shaf t.TDC o ccurs when the crank angle is 0° when ther e is no pist on pin off set, and pr ior t o the cr ank angle r eaching 0° when ther e is a p ositiv e pist on pin off set. The pist on lo cation is a p ositiv e value a t bottom-dead-c enter (BDC), that is, when the cr ank shaf t is p erfectly aligned b etween the pist on pin and the cr ank pin. The v alue of at BDC is equal t o when ther e is no pist on pin off set, and gr eater than when ther e is a nonz ero pist on pin off set (p ositiv e or nega tive). The cur rent crank angle is c alcula ted fr om (11.26) wher e is the Starting C rank A ngle and is the Crank S haft Speed . The Piston S troke Cutoff and Minimum Valve Lif t values ar e used t o control the ac tual v alues of the valve lift and pist on str oke such tha t (11.27) wher e is the v alve lift comput ed fr om the appr opriate valve pr ofiles , is the Minimum Valve Lift, is the str oke calcula ted fr om Equa tion 11.25 (p.1315 ), and is the Piston S troke Cutoff. (See Defining M otion/G eometr y Attribut es of M esh Z ones (p.1322 ) on ho w the Piston S troke Cutoff is used to control the onset of la yering in the c ylinder chamb er.) Enable the Write In-C ylinder Output option then click the Output C ontrols... butt on if y ou w ant to specify sp ecific output par amet ers.The In-C ylinder Output C ontrols D ialog Box (p.3578 ) will op en, wher e 1315Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshesyou c an sp ecify v arious quan tities needed f or the c alcula tion of swir l and tumble along with the fr e- quenc y of wr iting the output t o the chosen file . Swirl is used t o descr ibe cir cula tion ab out the c ylinder axis.Tumble flo w cir cula tes ar ound an axis p erpendicular t o the c ylinder axis , orthogonal t o swir l flo w. Figur e 11.55: The In-C ylinder Output C ontrols D ialo g Box The f ollowing list descr ibes the In-C ylinder Output C ontrols D ialog Box (p.3578 ). In-C ylinder D ata Write Frequenc y is an in teger en try sp ecifying the in terval in numb er of time-st eps. Make sur e tha t a v alue other than 0 is used f or the fr equenc y, in or der t o allo w you t o complet e your setup . Swirl Center M etho d is a dr op-do wn list tha t allo ws you t o selec t the metho d to calcula te the swir l center.The list c ontains center of gr avity and fixed, with center of gr avity being the default v alue . center of gr avity option c alcula tes the swir l center inside the c ode and is used as the c enter of gr avity of the chosen cell z ones . fixed option enables y ou t o sp ecify a swir l center in the en tries b elow the dr op-do wn list. In addition t o these t wo options , you c an chose t o use y our o wn c ompiled UDF t o calcula te the swir l center. For details on using a d ynamic mesh UDF , see the Fluen t Customiza tion M anual for inf ormation on user-defined func tions . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1316Modeling F lows Using S liding and D ynamic M eshesCell Z ones is a list tha t displa ys the names of all e xisting c ell z ones in the c ase files .You c an selec t only the z ones relevant for the swir l and tumble c alcula tions . Swirl Axis specifies the swir l axis with thr ee en tries f or the dir ectional c omp onen ts. By default ,X,Y,Z = 0,1,0. Tumble A xis specifies the dir ectional c omp onen ts of Tumble A xis in X,Y,Z directions . By default ,X,Y,Z = 0,0,1.This applies only in 3D . Cross Tumble A xis specifies the dir ectional c omp onen ts of Cross Tumble A xis in X,Y,Z directions . By default ,X,Y,Z = 1, 0,0.This applies only in 3D . File N ame specifies the name of the In-C ylinder output file . By default , the file name c ontains the name of the c ase file app ended with a .txt extension. The In-C ylinder specific output c ontrols c an also b e controlled using the TUI as f ollows: Go to define/dynamic-mesh/controls/in-cylinder-output? Enable in-cylinder output?[no] yes Output Write Frequency[0] 10 Cell zone name/id(1)[()] 2 Cell zone name/id(1)[()] File Name[‘‘/nfs/devvault/data9/ic-sp-output.txt’’] Swirl Center Method: (fixed cg user-defined) Option[cg] Swirl Axis x[0] Swirl Axis y[1] Swirl Axis z[0] Tumble Axis x[0] Tumble Axis y[0] Tumble Axis z[1] Cross Tumble Axis x[1] Cross Tumble Axis y[0] Cross Tumble Axis z[0] If you selec t fixed as the choic e at Swirl Center M etho d then y ou will b e pr ompt ed t o en ter the swir l center as f ollows: Swirl Center(x) (mm) [0] Swirl Center(y) (mm) [0] Swirl Center(z) (mm) [0] If a swir l center metho d UDF has b een c ompiled alr eady and loaded in to UDF then y ou c an cho ose user-defined as the swir l center metho d option, in such a c ase the f ollowing is the sequenc e of prompts . Swirl Center UDF[] swirl_udf::libudf If the name of the UDF libr ary is libudf then y ou c an omit this and en ter in the swir l center UDF[]swirl_udf , other wise the name of the UDF f ollowed b y the UDF libr ary name with symb ol:: in b etween, should b e en tered. 1317Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshesBy filling up the v arious en tries tha t are needed in the In-C ylinder Output C ontrols D ialog Box (p.3578 ) and pr essing the OK butt on, the swir l and tumble c alcula tions will b e wr itten a t the chosen fr equenc y to the chosen file while doing the solution r un. Details of the quan tities wr itten t o the file ar e as f ollows: CA = C rank A ngle m = M ass of the en tire fluid c ontained in the selec ted c ell z ones L = A ngular momen tum v ector of fluid mass c ontained in selec ted c ell z ones with r espect to the swir l center = M agnitude of angular momen tum of fluid = S wirl Axis = Tumble A xis = C ross Tumble A xis I = M omen t of iner tia of the fluid mass ab out S wirl axis I = M omen t of iner tia of the fluid mass ab out Tumble A xis I = M omen t of iner tia of the fluid mass ab out C ross Tumble A xis = D ot pr oduc t between t wo vectors Altogether , the pr evious quan tities ar e combined t o yield eigh t columns of da ta in the output file , as shown in the figur e tha t follows: Figur e 11.56: Sample Output F ile S howing Various Q uan tities 11.6.4.1. Using the In-C ylinder O ption This sec tion descr ibes the pr oblem setup pr ocedur e for an in-c ylinder d ynamic mesh simula tion. 11.6.4.1.1. Overview Consider the 2D in-c ylinder e xample sho wn in Figur e 11.57: A 2D In-C ylinder G eometr y (p.1319 ) for a typic al p ent-roof engine . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1318Modeling F lows Using S liding and D ynamic M eshesFigur e 11.57: A 2D In-C ylinder G eometr y In setting up the d ynamic mesh mo del f or an in-c ylinder pr oblem, you must c onsider the f ollowing issues: •how to pr ovide the pr oper mesh t opology for the v olume mesh up date metho ds (smo othing , dynamic layering, and lo cal or z onal r emeshing) •how to define the motion a ttribut es and geometr y for the v alve and pist on sur faces •how to addr ess the op ening and closing of the in take and e xhaust v alves •how to sp ecify the sequenc e of e vents tha t controls the in-c ylinder simula tion 11.6.4.1.2. Defining the Mesh Topolo gy ANSY S Fluen t requir es tha t you pr ovide an initial v olume mesh with the appr opriate mesh t opology such tha t the v arious mesh up date metho ds descr ibed in Dynamic M esh U pdate M etho ds (p.1267 ) can b e used t o aut oma tically up date the d ynamic mesh. However, ANSY S Fluen t do es not r equir e you t o set up all in-c ylinder pr oblems using the same mesh t opology.When y ou gener ate the mesh for y our in-c ylinder pr oblem, you must c onsider the v arious mesh r egions tha t you c an iden tify as moving , def orming , or sta tionar y, and gener ate these mesh r egions with the appr opriate cell shap e. The mesh t opology for the e xample pr oblem in Figur e 11.57: A 2D In-C ylinder G eometr y (p.1319 ) is shown in Figur e 11.58: Mesh Topology Showing the Various M esh R egions (p.1320 ), and the c orres- ponding v olume mesh is sho wn in Figur e 11.59: Mesh A ssociated With the C hosen Topology (p.1320 ). 1319Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshesFigur e 11.58: Mesh Topology Showing the Various M esh Regions Figur e 11.59: Mesh A ssociated With the C hosen Topology Because of the r ectilinear motion of the mo ving sur faces, you c an use d ynamic la yering z ones t o represen t the mesh r egions sw ept out b y the mo ving sur faces.These r egions ar e the r egions ab ove the t op sur faces of the in take and e xhaust v alves and ab ove the pist on head sur face, and must b e meshed with quadr ilateral or he xahedr al cells (as r equir ed b y the d ynamic la yering metho d). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1320Modeling F lows Using S liding and D ynamic M eshesFor the chamb er region, you must define a r emeshing z one (tr iangular c ells) t o acc ommo date the various p ositions of the v alves in the c ourse of the simula tion. In this r egion, the motion of the boundar ies (v alves and pist on sur faces) is pr opaga ted t o the in terior no des thr ough smo othing . If the c ell qualit y viola tes an y of the r emeshing cr iteria tha t you ha ve sp ecified , ANSY S Fluen t will automa tically agglomer ate these c ells and r emesh them. Further mor e, ANSY S Fluen t will also r emesh the def orming fac es (based on the minimum and maximum length sc ale tha t you ha ve sp ecified) on the c ylinder w alls as w ell as those on the sliding in terfaces used t o connec t the chamb er cell zone t o the la yering z ones ab ove the v alve sur faces. For the in take and e xhaust p ort regions , you c an use either tr iangular or quadr ilateral cell z ones because these z ones ar e not mo ving or def orming . ANSY S Fluen t will aut oma tically mar k these r egions as sta tionar y zones and will not apply an y mesh motion metho d on these c ell z ones . The d ynamic la yering r egions ab ove the pist on and v alves ar e conformal with the adjac ent cell z one in the chamb er and p orts, respectively, so y ou do not ha ve to use sliding in terfaces to connec t these cell z ones t ogether . However, you must use sliding in terfaces to connec t the d ynamic la yering r egions above the v alves and the r emeshing r egion in the chamb er.This is sho wn in Figur e 11.60: The U se of S liding In terfaces to Connec t the Exhaust Valve La yering Z one t o the R emeshing Z one (p.1321 ) with the e xhaust v alve almost a t full e xtension. Notice tha t cells on the chamb er side of the in terface zone ar e remeshed (tha t is, split or mer ged) as the in terface zone op ens and closes b ecause of the motion of the e xhaust v alve. Figur e 11.60: The U se of S liding In terfaces t o Connec t the E xhaust Valve Layering Z one t o the Remeshing Z one 1321Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshes11.6.4.1.3. Defining Motion/G eometr y Attribut es of Mesh Z ones As the pist on mo ves do wn fr om the TDC t o the BDC p osition, you must e xpand the r emeshing r egion such tha t it c an acc ommo date the v alves when the y are fully e xtended .To acc omplish this , you must sp ecify the d ynamic la yering z one adjac ent to the pist on sur face to mo ve with the pist on un til some sp ecified distanc e from the TDC p osition. Beyond this cut off distanc e, the motion of the la yering zone is st opp ed and the pist on w all is allo wed t o continue t o the BDC p osition. Because ther e is relative motion b etween the pist on head sur face and the no w non-mo ving d ynamic la yering z one , cell la yers will b e added when the ideal la yer heigh t criteria is viola ted.Figur e 11.61: Mesh S equenc e 1 (p.1322 ) to Figur e 11.66: Mesh S equenc e 6 (p.1325 ) sho w the sequenc e of meshes b efore and af ter the onset of c ell la yering when the motion in the la yering z one ab ove the pist on sur face is st opp ed (sho wn with = 5°). Figur e 11.61: Mesh S equenc e 1 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1322Modeling F lows Using S liding and D ynamic M eshesFigur e 11.62: Mesh S equenc e 2 Figur e 11.63: Mesh S equenc e 3 1323Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshesFigur e 11.64: Mesh S equenc e 4 Figur e 11.65: Mesh S equenc e 5 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1324Modeling F lows Using S liding and D ynamic M eshesFigur e 11.66: Mesh S equenc e 6 ANSY S Fluen t provides built-in func tions t o handle the full pist on motion and the limit ed pist on motion f or the d ynamic la yering z one ab ove the pist on sur face.When y ou define the motion a ttribut e of the d ynamic la yering z one ab ove the pist on sur face, you must use the limit ed pist on motion func tion ( **pist on-limit** in the Motion UDF/P rofile field in the Dynamic M esh Z ones D ialog Box (p.3587 )). Note tha t you must define the par amet ers used b y these func tions b efore you c an use them. In the cur rent example , the cr ank r adius is 40 mm and the c onnec ting r od length is 140 mm. The pist on str oke cut off is assumed t o happ en a t 25 mm fr om TDC p osition. The lif t as a func tion of cr ank angle b etween and is sho wn in Figur e 11.67: Piston P osition (m) as a F unction of C rank A ngle (deg) (p.1326 ) for b oth limit ed and full pist on motion. 1325Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshesFigur e 11.67: Piston P osition (m) as a F unc tion of C rank A ngle (deg) To define the motion of the v alves, you must use pr ofiles tha t descr ibe the v ariation of v alve lift with cr ank angle . ANSY S Fluen t expects certain pr ofile fields t o be used t o define the lif t and the crank angle . For e xample , consider the f ollowing simplified pr ofile definition: ((ex-valve 5 point) (angle 0 180 270 360 720) (lift 0.05 0.05 1.8 0.05 0.05)) ((in-valve 5 point) (angle 0 355 440 540 720) (lift 0.05 0.05 2.0 0.05 0.05)) ANSY S Fluen t expects the angle and lift fields t o define the cr ank angle and lif t variations , re- spectively.The angle must b e sp ecified in degr ees and the lif t values must b e in met ers.The ac tual valve lift profiles tha t you will use f or the cur rent example ar e sho wn in Figur e 11.68: Intake and Exhaust Valve Lif t (m) as a F unction of C rank A ngle (deg) (p.1327 ). Notice tha t ther e is an o verlapp ed period wher e both the in take and e xhaust v alves ar e op en. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1326Modeling F lows Using S liding and D ynamic M eshesFigur e 11.68: Intake and E xhaust Valve Lif t (m) as a F unc tion of C rank A ngle (deg) The v alve lift profiles and the built-in func tions will descr ibe ho w each sur face mo ves as a func tion of cr ank angle with r espect to some r eference point. For e xample , the v alve lift is z ero when the valve is fully closed and the v alve lift is maximum when it is fully op en. In or der t o mo ve the sur faces, ANSY S Fluen t requir es tha t you sp ecify the dir ection of motion f or each sur face. ANSY S Fluen t will then up date the “center of gr avity” of each sur face such tha t (11.28) wher e is some r eference position, is the unit v ector in the dir ection of motion, and is either the v alve or the pist on distanc e with r espect to the r eference position . Note tha t the unit vector of the dir ection of motion is sp ecified t o point in the nega tive dir ection. For e xample , the correct intake valve axis f or this e xample is , as sho wn in Figur e 11.69: Definition of Valve Zone A ttribut es (In take Valve) (p.1328 ). 1327Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshesFigur e 11.69: Definition of Valve Zone A ttribut es (In take Valve) 11.6.4.1.4. Defining Valve O pening and C losur e ANSY S Fluen t assumes tha t onc e you ha ve set up the mesh t opology, the mesh t opology is unchanged throughout the en tire simula tion. Therefore, ANSY S Fluen t do es not allo w you t o complet ely close the v alves such tha t the c ells b etween the v alve and the v alve sea t become degener ate (fla t cells) when these sur faces c ome in c ontact (remo ving these fla t cells w ould r equir e the cr eation of new boundar y fac e zones). To pr event the c ollapse , you must define a minimum v alve lift and ANSY S Fluen t will aut oma tically st op the motion of the v alve when the v alve lift is smaller than the minimum valve lift value .The minimum v alve lift value c an b e sp ecified in the In-C ylinder tab of the Options Dialog Box (p.3575 ). For the cur rent example , a minimum v alve lift value of 0.1 mm is assumed . When the v alve position is smaller than the minimum v alve lift value , it is nor mal pr actice to assume that the v alve is closed .The ac tual closing of the v alves is acc omplished b y deleting the sliding in- terfaces tha t connec t the chamb er cell z one t o the d ynamic la yering z ones on the v alves.The in terface zones ar e then c onverted t o walls t o close off the “gaps ” between the v alves and the v alve sea ts. The v alve op ening is achie ved b y the r everse pr ocess.When the v alve lift has r eached b eyond the minimum v alve lift value , the v alve is assumed t o be op en and y ou c an r edefine the sliding in terfaces such tha t the chamb er zone is no w connec ted t o the d ynamic la yering z ones ab ove the v alves. 11.6.5. Six DOF S olver S ettings ANSY S Fluen t’s six degr ees of fr eedom (six DOF) solv er comput es e xternal f orces and momen ts (such as aer odynamic and gr avitational f orces and momen ts) on objec ts tha t under go r igid b ody motion. These f orces ar e comput ed b y numer ical in tegration of pr essur e and shear str ess o ver the objec t’s surfaces. Additional load f orces c an b e added , such as injec tor forces, thrust (pr opulsiv e) forces, and momen ts pr oduced b y a c oil spr ing.This t echnique , along with the ANSY S Fluen t solv er and the use of d ynamic meshes , can b e readily applied t o man y useful applic ations , such as st ore separ ation [112] (p.4011 ),[123] (p.4011 ). Note tha t the objec ts ma y be comp osed of multiple z ones . To use the six degr ees of fr eedom solv er for y our tr ansien t dynamic mesh simula tion, perform the following st eps: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1328Modeling F lows Using S liding and D ynamic M eshes1.Enable the Six DOF option in the Options group b ox of the Dynamic M esh Task P age (p.3567 ) (Fig- ure 11.13: The D ynamic M esh Task P age (p.1267 )) and click the Settings ... butt on.The Options dialo g box will op en, wher e you c an click the Six DOF tab ( Figur e 11.70: The S ix DOF Tab of the Options D ialog Box (p.1329 )). Figur e 11.70: The S ix DOF Tab of the Options D ialo g Box This tab allo ws you t o perform the f ollowing ac tions: •You c an cr eate and manage sets of six DOF pr operties f or rigid b ody motion b y using the list and butt ons under Six DOF P roperties ; other wise , you will ha ve to create one or mor e user-defined func tions . See Setting R igid B ody Motion A ttribut es for the S ix DOF S olver (p.1330 ) for details . •You c an sp ecify the gr avitational acc eleration f or the x,y, and z directions either in this dialo g box, or in the Operating C onditions dialo g box. •You c an k eep tr ack of an objec t’s motion hist ory by enabling the Write M otion Hist ory option and en tering a File N ame . A single motion hist ory file will b e gener ated f or each mo ving objec t, which c an b e used t o displa y zone motion f or p ostpr ocessing y our r esults . Note tha t the file name y ou sp ecify will b e app ended with the name of the set of six DOF pr operties / UDF , as well as the e xtension .6dof ; you c an change the e xtension b y sp ecifying y our o wn as par t of the File N ame . 2.If the mesh motion of y our six DOF simula tion dep ends on the fluid flo w, it is b eneficial t o enable implicit mesh up dating (as descr ibed in Implicit U pdate Settings (p.1332 )). If the implicit mesh up date is not sufficien t 1329Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshesto stabiliz e the solv er due t o the fluid motion, solution stabiliza tion ma y be nec essar y.The solution stabil- ization settings ar e set in the Solver Options tab of the Dynamic M esh Z ones dialo g box for b oundar y zones ( Solution S tabiliza tion f or D ynamic M esh B oundar y Zones (p.1364 )). 3.Define the r igid-b ody zone(s) tha t mak e up each mo ving objec t by using the Dynamic M esh Z ones D ialog Box (p.3587 ), as descr ibed in Rigid B ody Motion (p.1349 ). Setup → Dynamic M esh → Create/Edit... 11.6.5.1. Setting R igid B ody Motion A ttribut es for the S ix DOF S olver As par t of the six DOF solv er settings , you must pr ovide either a set of pr operties or a user-defined func tion (UDF) f or each mo ving objec t, in or der t o define its o verall mass , rotational iner tia, constr aints, loading fr om sour ces other than aer odynamics and gr avity, and so on. Each objec t needs e xactly one set of pr operties / UDF , regar dless of ho w man y zones mak e up the objec t. Note tha t if y ou ha ve multiple iden tical objec ts, you c an cr eate an initial set of pr operties / UDF , and then mak e copies with unique names . If the motion of the objec t is c omple x or if only half of the objec t is mo deled using a symmetr y zone , then y ou will need t o use a UDF (see DEFINE_SDOF_PROPERTIES in the Fluent C ustomization Manual for the details); other wise , it is easier t o use a set of pr operties. Such sets ar e created using the Six DOF P roperties dialo g box, which is op ened b y click ing the Create/Edit... butt on in the Six DOF tab of the Options D ialog Box (p.3575 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1330Modeling F lows Using S liding and D ynamic M eshesFigur e 11.71: The S ix DOF P roperties D ialo g Box In the Six DOF P roperties dialo g box, you will need t o pr ovide a Name for the set of pr operties, define the other fields in the dialo g box, and click Create. For six DOF motion, the only other fields tha t must b e defined ar e the Mass and the Iner tia Tensor comp onen ts. Note tha t the iner tia t ensor c omp onen ts ar e defined r elative to the Center of G ravity and Rigid B ody Or ientation settings defined in the Dynamic M esh Z ones D ialog Box (p.3587 ); the latter settings allo w you t o use a c oordina te sy stem tha t is lo cal (r ather than global), if tha t is mor e convenien t. If you w ant to sp ecify tha t the d ynamic objec t be limit ed t o one DOF motion (tha t is, either a simple transla tion or a simple r otation), enable the One DOF Transla tion or One DOF Rota tion option and define the settings in the One DOF group b ox.The f ollowing figur e sho ws an e xample of a one DOF transla tion: 1331Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshesFigur e 11.72: A C heck Valve with One DOF Transla tion Note the f ollowing ab out one DOF motion settings: •For rotation, you will define the Mass of the d ynamic objec t, in addition t o the Momen t of Iner tia. •For 2D c ases with r otation, the axis will b e either the p ositiv e or nega tive z direction, dep ending on the sign of the v alue y ou en ter for Z in the Axis group b ox. •You ha ve the option of defining a H ooke's la w Spring tha t exerts forces / t orques on the d ynamic objec t. It is a c ompr ession / e xtension spr ing f or tr ansla tions , and it is a t orsion spr ing f or rotations . For e xample: for a tr ansla tion, the sp ecified Constan t will b e multiplied b y the distanc e of the d y- namic objec t from its initial lo cation. This f orce will b e combined with a Preload value tha t is constan tly applied t o the d ynamic objec t, in or der t o pr oduce the net spr ing loading . Note tha t the Preload can b e a p ositiv e or nega tive value , and is defined r elative to the Direction . •You c an limit the r ange of motion of the d ynamic objec t by enabling the Constr ained option and defining the settings in the Referenc e Point group b ox (for tr ansla tion) or the Referenc e Angle group b ox (for rotation). For e xample: for a tr ansla tion, you c ould en ter 2 inches f or the Location , in or der t o assign a c o- ordina te value t o a p oint located on the d ynamic objec t in its initial p osition. Then y ou w ould define the r ange of motion allo wed r elative to tha t coordina te: you w ould en ter 1.2 and 2 inches for the Minimum and Maximum , respectively, if y ou w anted the objec t to only b e allo wed t o mo ve .8 inches in the dir ection opp osite to the Direction vector.The v alue of the Location is arbitr ary, and allo ws you t o define the r ange using v alues tha t are most c onvenien t for y our pr oblem. •The initial p osition / or ientation of the objec t (which is used t o calcula te the spr ing loading and/or r ange of motion) is established when y ou cr eate the d ynamic z one(s) using the Dynamic M esh Z ones D ialog Box (p.3587 ). 11.6.6. Implicit U pdate Settings For tr ansien t problems , you c an enable implicit mesh up dating when y ou w ant to ha ve the d ynamic mesh up dated dur ing a time st ep (as opp osed t o just a t the b eginning of a time st ep). This c apabilit y is beneficial only f or applic ations in which the mesh motion dep ends on the flo w field (f or e xample , cases tha t use the six DOF solv er or in volve fluid-str ucture in teraction). For such applic ations , having the mesh motion up dated within the time st ep based on the c onverging flo w solution r esults in a stronger c oupling b etween the flo w solution and the mesh motion, and leads t o a mor e robust solv er Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1332Modeling F lows Using S liding and D ynamic M eshesrun. Implicit mesh up dating allo ws you t o run simula tions tha t other wise c ould not b e solv ed or w ould requir e an unr easonably small time st ep. Note tha t implicit mesh up dating c annot b e used with the f ollowing: •the densit y-based solv er when Explicit is selec ted fr om the Transien t Formula tion drop-do wn menu in the Solution M etho ds task page •steady-sta te solutions •in-cylinder applic ations To enable implicit mesh up dating , perform the f ollowing st eps: 1.Enable Implicit U pdate in the Options group b ox of the Dynamic M esh Task P age (p.3567 ) (Fig- ure 11.13: The D ynamic M esh Task P age (p.1267 )). 2.Click the Settings ... butt on t o op en the Options D ialog Box (p.3575 ). Figur e 11.73: The Implicit U pdate Tab of the Options D ialo g Box Click the Implicit U pdate tab and en ter v alues f or the settings . a.Enter a v alue f or Update In terval, in or der t o sp ecify the fr equenc y in it erations a t which the mesh will b e up dated within a time st ep. 1333Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshesb.Enter a v alue (within the r ange of 0 t o 1) f or Motion Relaxa tion , in or der t o define the relaxa tion of the motion (tha t is, displac emen t of the no des) dur ing the mesh up date.The relaxa tion of the displac emen ts is defined b y the f ollowing equa tion: (11.29) wher e is the no de p osition a t iteration (within a time st ep), is the comput ed no de p osition (based on the flo w field), and is the motion r elaxa tion. c.Enter a v alue f or Residual C riteria, in or der t o set the r elative residual thr eshold tha t is used t o check the motion c onvergenc e.The r esidual cr iteria is applied t o a r elative residual. ANSY S Fluen t scales the diff erence between the motion in it eration and it eration by the motion c omput ed a t the b eginning of the time st ep. If this r elative motion diff erence is smaller than the r esidual cr iteria, the mesh motion is c onsider ed c onverged . 3.If you ar e using a UDF t o comput e the motion, mak e sur e tha t the UDF uses the cur rent flo w field during each c all to comput e the motion (tha t is, no pr eviously st ored inf ormation should b e used). This is nec essar y, as the UDF will b e called each time the mesh is up dated — which c an b e se veral times within a time st ep, dep ending on wha t you en tered f or the Update In terval. 4.After you r un the simula tion, mak e sur e tha t the motion (and c onsequen tly, the solution) is pr operly converged . If the motion r equir es mor e iterations t o converge than the flo w field , a w arning will b e displa yed in the c onsole dur ing the it eration pr ocess. Note tha t the maximum numb er of it erations per time st ep (defined in the Run C alcula tion task page) is r espected b y the mesh motion c onvergenc e check. 11.6.7. Contact Detection S ettings Contact det ection is used t o det ect if the c omput ed mesh motion will r esult in c ontact of a mo ving surface with other sur rounding sur faces. If ther e is c ontact within sp ecified t oler ances, then the mesh motion of the mo ving z one c an b e constr ained using no dal c ontact inf ormation within user-defined func tions (S ee Example 2 under DEFINE_C ONT ACT in the Fluen t ). To enable c ontact det ection in y our d ynamic mesh simula tion, selec t the Contact Detection check box in the Options group of the Dynamic M esh task page . Click the Settings ... butt on t o op en the Options dialo g box and selec t the Contact Detection tab (see Figur e 11.74: The C ontact Detection Tab of the Options D ialog Box (p.1335 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1334Modeling F lows Using S liding and D ynamic M eshesFigur e 11.74: The C ontact Detection Tab of the Options D ialo g Box You c an selec t the fac e zones tha t will b e involved in the c ontact det ection pr ocess fr om the Face Zones list. While all eligible fac e zones in the Face Zones list ar e selec ted b y default , you c an cho ose to exclude c ertain z ones f or efficienc y. Only w alls and d ynamic z ones of t ype Rigid B ody or User- Defined can b e selec ted f or c ontact det ection. From the UDF drop-do wn list , you c an sp ecify a user-defined func tion tha t will b e invoked when contact has b een det ected. For mor e inf ormation ab out c ontact UDFs , see DEFINE_CONTACT in the Fluen t Customiza tion M anual . You must sp ecify a Proximit y Threshold value in or der t o enable the c ontact det ection pr ocess.When the distanc e between fac e zones falls b elow this thr eshold v alue , the UDF sp ecified in the UDF drop- down list is in voked. Cells adjac ent to fac e zones tha t fall b elow the Proximit y Threshold distanc e can also b e tagged and separ ated in to new c ell z ones dur ing the c ontact det ection pr ocess.This is useful f or sp ecifying diff erent flow conditions in c ontact regions dur ing the simula tion. To enable flo w control options , selec t the Flow C ontrol check b ox in the Contact Detection tab . Ad- ditional settings f or flo w control can then b e sp ecified b y click ing the Controls... butt on t o displa y the Flow C ontrols dialo g box (see Figur e 11.75: The F low C ontrols D ialog Box (p.1336 )). 1335Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshesFigur e 11.75: The F low C ontrols D ialo g Box In the Flow C ontrols dialo g box, you c an sp ecify a flo w control zone (f or e xample , restrictions , and so on) f or an y cell z one in the mesh. To cr eate a flo w control zone , selec t a z one fr om the Cell Z ones list, specify a new name in the Flow C ontrol Z one text box, and click the Create Zone butt on. Onc e the flo w control zone has b een cr eated, it b ecomes a vailable in the Cell Z one C onditions task page , wher e additional ph ysical pr operties (f or e xample , iner tial and/or visc ous p orous r esistanc e) can b e specified . During the simula tion, onc e cells in the c ontact region ha ve been separ ated in to new z ones , the ph ysical pr operties sp ecified in the r espective flo w control zone ar e copied t o the newly separ ated cell z one . 11.6.8. Defining D ynamic M esh E vents If you ar e simula ting a tr ansien t flo w, you c an use the e vents in ANSY S Fluen t to control the timing of specific e vents dur ing the c ourse of the simula tion. With in-c ylinder flo ws for e xample , you ma y want to op en the e xhaust v alve (represen ted b y a pair of def orming sliding in terfaces) b y creating an e vent to cr eate the sliding in terfaces a t some cr ank angle .You c an also use d ynamic mesh e vents to control when t o susp end the motion of a fac e or c ell z one b y creating the appr opriate events based on the crank angle or time . Note tha t in-c ylinder flo ws are crank angle-based , wher eas all other flo ws are time-based . 11.6.8.1. Procedur e for D efining E vents You c an define the e vents using the Dynamic M esh E vents D ialog Box (p.3584 ) (Figur e 11.76: The D y- namic M esh E vents D ialog Box (p.1337 )). Setup → Dynamic M esh → Events... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1336Modeling F lows Using S liding and D ynamic M eshesFigur e 11.76: The D ynamic M esh E vents D ialo g Box The pr ocedur e for defining e vents is as f ollows: 1.Increase the Numb er of E vents value t o the numb er of e vents you w ant to sp ecify . As this v alue is in- creased , additional e vent en tries in the dialo g box will b ecome editable . 2.Enable the check b ox ne xt to the first e vent and en ter a name f or the e vent under the Name heading . 3.Specify either the time or the cr ank angle a t which y ou w ant the e vent to occur . For in-c ylinder flo ws, specify the cr ank angle a t which y ou w ant the e vent to occur under At Crank Angle . For non-in-c ylinder flo ws, specify the time (in sec onds) a t which y ou w ant the e vent to occur under At Time . It is not nec essar y to sp ecify the e vents in or der of incr easing time or cr ank angle , but it ma y be easier t o keep tr ack of e vents if y ou sp ecify them in the or der of incr easing time or angle . 4.Click the Define ... butt on t o op en the Define E vent Dialog Box (p.3585 ) (Figur e 11.77: The D efine E vent Dialog Box (p.1338 )). 1337Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshesFigur e 11.77: The D efine E vent Dialo g Box 5.In the Define E vent Dialog Box (p.3585 ), cho ose the t ype of e vent by selec ting Change Z one Type,Copy Zone BC ,Activate Cell Z one ,Deac tivate Cell Z one ,Create Sliding In terface,Delet e Sliding In terface, Change M otion A ttribut e,Change Time S tep S ize,Change U nder-Relaxa tion F actors,Inser t Boundar y Zone L ayer,Remo ve Boundar y Zone L ayer,Inser t Interior Z one L ayer,Remo ve In terior Zone L ayer,Inser t Cell L ayer,Remo ve Cell L ayer,Execut e Command ,Replac e M esh,Iner t EGR Reset , or Diesel U nstead y Flamelet Reset in the Type drop-do wn list. These e vent types and their definitions are descr ibed la ter in this sec tion. 6.Repeat steps 2–5 f or the other e vents, if relevant. 7.Click Apply in the Dynamic M esh E vents D ialog Box (p.3584 ) after you finish defining all e vents. 8.To pla y the e vents to check tha t the y are defined c orrectly, click the Preview... butt on in the Dynamic Mesh E vents D ialog Box (p.3584 ).This displa ys the Events Preview D ialog Box (p.3587 ). For in-c ylinder flo ws, you use the Events Preview D ialog Box (p.3587 ) (Figur e 11.78: The E vents Preview D ialog Box for In-C ylinder F lows (p.1339 )), to en ter the cr ank angles a t which y ou w ant to start and end the pla yback in the Start Crank A ngle and End C rank A ngle fields , respectively. For non-in-c ylinder flo ws, you use the Events Preview D ialog Box (p.3587 ) to en ter the time a t which you w ant to star t and end the pla yback in the Start Time and End Time fields , respectively. Specify the siz e of the st ep t o tak e dur ing the pla yback in the Incr emen t field . Click Preview to play back the e vents. ANSY S Fluen t will pla y the e vents at the time (or cr ank angle in the c ase of in-cylinder flo ws) sp ecified f or each e vent and r eport when each e vent occurs in the t ext (console) windo w. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1338Modeling F lows Using S liding and D ynamic M eshesFigur e 11.78: The E vents P review D ialo g Box for In-C ylinder F lows For in-c ylinder simula tions , you must sp ecify the e vents for one c omplet e engine c ycle. In the subsequen t cycles, the e vents ar e execut ed whene ver (11.30) wher e is the e vent crank angle , is the cur rent crank angle c alcula ted fr om Equa- tion 11.26 (p.1315 ), is the cr ank angle p eriod for one c ycle, and is some in teger . As an e xample , for in-c ylinder simula tions , you ar e not r equir ed t o sp ecify the e vent crank angle to correspond e xactly t o the cur rent crank angle c alcula ted fr om Equa tion 11.26 (p.1315 ). ANSY S Fluen t will e xecut e an e vent if the cur rent crank angle is b etween wher e is the equiv alen t change in cr ank angle f or the time st ep. For e xample , if the e vent preview is e xecut ed between cr ank angle of and (crank p eriod is ) using an incr emen t of , ANSY S Fluen t will r eport the f ollowing in the t ext windo w. Execute Event: open-in-valve-left (defined at: 353.10, current angle: 353.00) Execute Event: open-in-valve-right (defined at: 353.00, current angle: 353.00) Execute Event: close-ex-valve-right (defined at: 355.60, current angle: 356.00) Execute Event: close-ex-valve-left (defined at: 357.80, current angle: 358.00) Execute Event: close-in-valve-left (defined at: 571.60, current angle: 572.00) Execute Event: close-in-valve-right (defined at: 571.80, current angle: 572.00) Execute Event: open-ex-valve-right (defined at: 137.10, current angle: 857.00) Execute Event: open-ex-valve-left (defined at: 139.00, current angle: 859.00) Notice tha t events defined a t and are execut ed a t and , respectively, be- cause the y sa tisfy the c ondition of Equa tion 11.30 (p.1339 ). 11.6.8.2. Defining E vents for In-C ylinder A pplic ations ANSY S Fluen t will aut oma tically limit the v alve lift values dep ending on the sp ecified minimum v alve lift value . However, the c onversion of the sliding in terface zones t o walls (and vic e versa) is acc om- plished via the in-c ylinder e vents (see Defining D ynamic M esh E vents (p.1336 )). For e xample , if the exhaust v alve closes a t before TDC p osition, you must define a Delet e Sliding In terface event at the cr ank angle of .You must define similar e vents for the in take valve op ening (using the Create Sliding In terface event), the in take valve closing ( Delet e Sliding In terface event), and the exhaust v alve op ening ( Create Sliding In terface event) at the r espective crank angles . For the cur rent example , the e xhaust v alve is assumed t o be op en b etween and and the intake valve is op en b etween a t and . 1339Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshes11.6.8.2.1. Events Each of the a vailable e vents is descr ibed b elow. 11.6.8.2.2. Changing the Z one Type You c an change the t ype of a z one t o be a w all, or an in terface, interior, fluid , or solid z one dur ing your simula tion. To change the t ype of a z one , selec t Change Z one Type in the Type drop-do wn list in the Define E vent Dialog Box (p.3585 ) (Figur e 11.77: The D efine E vent Dialog Box (p.1338 )). Selec t the z one(s) tha t you w ant to change in the Zone list, and then selec t the new z one t ype in the New Zone Type drop-do wn list. 11.6.8.2.3. Copying Z one B oundar y Conditions You c an c opy boundar y conditions fr om one z one t o other z ones dur ing y our simula tion. If, for e x- ample , you ha ve changed an inlet z one t o type wall with the Change Z one Type event, you c an set the b oundar y conditions of the new z one t ype by simply c opying the b oundar y conditions fr om a known z one with the c orresponding z one t ype. To copy boundar y conditions fr om one z one t o another , selec t Copy Zone BC in the Type drop- down list in the Define E vent Dialog Box (p.3585 ) (Figur e 11.77: The D efine E vent Dialog Box (p.1338 )). In the From Z one drop-do wn list , selec t the z one tha t has the c onditions y ou w ant to copy. In the To Zone(s) list, selec t the z one or z ones t o which y ou w ant to copy the c onditions . ANSY S Fluen t will set all of the b oundar y conditions f or the z ones selec ted in the To Zone(s) list t o be the same as the c onditions f or the z one selec ted in the From Z one list. (You c annot c opy a subset of the c onditions , such as only the ther mal c onditions .) Note tha t you c annot c opy conditions fr om e xternal w alls t o in ternal (tha t is, two-sided) w alls, or vice versa, if the ener gy equa tion is b eing solv ed, sinc e the ther mal c onditions f or e xternal and in- ternal w alls ar e diff erent. 11.6.8.2.4. Activating a C ell Z one To ac tivate a c ell z one , selec t Activate Cell Z one in the Type drop-do wn list in the Define E vent Dialog Box (p.3585 ) (Figur e 11.77: The D efine E vent Dialog Box (p.1338 )), then selec t the z one tha t you want to ac tivate in the Zone(s) list. For mor e inf ormation, see Replacing , Deleting , Deactivating , and Activating Z ones (p.815). 11.6.8.2.5. Deac tivating a C ell Z one To deac tivate a c ell z one , selec t Deac tivate Cell Z one in the Type drop-do wn list in the Define E vent Dialog Box (p.3585 ) (Figur e 11.77: The D efine E vent Dialog Box (p.1338 )), then selec t the z one tha t you want to deac tivate in the Zone(s) list. Only deac tivated z ones c an b e ac tivated.When a z one is deac tivated, ANSY S Fluen t skips the z one during the c alcula tions . For mor e inf ormation, see Replacing , Deleting , Deactivating , and A ctivating Zones (p.815). 11.6.8.2.6. Creating a Sliding Int erface To cr eate a sliding in terface dur ing y our simula tion, selec t Create Sliding In terface in the Type drop-do wn list in the Define E vent Dialog Box (p.3585 ) (Figur e 11.79: The D efine E vent Dialog Box for the C reating S liding In terface Option (p.1341 )). Enter a name f or the sliding in terface in the Interface Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1340Modeling F lows Using S liding and D ynamic M eshesName field . Selec t the z ones on either side of the in terface in the Interface Zone 1 and Interface Zone 2 drop-do wn lists . You ha ve the option t o selec t an y numb er of z ones list ed under each of the in terface zones . ANSY S Fluen t calcula tes in tersec tions b etween all p ossible c ombina tions of the lef t and r ight side of the interfaces, allo wing y ou mor e fle xibilit y in t erms of cr eating z ones and defining the in terfaces. Figur e 11.79: The D efine E vent Dialo g Box for the C reating S liding In terface Option Imp ortant If ANSY S Fluen t finds another in terface with the same name as defined in the e vent, then the old in terface will b e delet ed and a new one cr eated as defined in the d ynamic mesh event. If the in terface zones tha t you selec ted ab ove do not o verlap each other c omplet ely, the non-o ver- lapp ed r egions on each in terface zones ar e put in to separ ate wall z ones b y ANSY S Fluen t. If these wall z ones (tha t is, non-o verlapp ed r egions) ha ve motion a ttribut es asso ciated with them, their motion c an only b e sp ecified b y copying the motion fr om another d ynamic z one b y selec ting the appr opriate dynamic z ones in the Wall 1 M otion and Wall 2 M otion drop-do wn lists , respectively. Note tha t you do not ha ve to change the b oundar y type from w all t o in terface.When the Create Sliding In terface event is e xecut ed, ANSY S Fluen t will aut oma tically change the b oundar y type of the fac e zones selec ted in Interface Zone 1 and Interface Zone 2 to type in terface before the sliding interface is cr eated. 1341Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshes11.6.8.2.7. Deleting a Sliding Int erface To delet e a sliding in terface tha t has b een cr eated ear lier in y our simula tion, selec t Delet e Sliding Interface in the Type drop-do wn list in the Define E vent Dialog Box (p.3585 ) (Figur e 11.77: The D efine Event Dialog Box (p.1338 )). Enter the name of the sliding in terface to be delet ed in the Interface Name field . As with the Create Sliding In terface event, ANSY S Fluen t will aut oma tically change the c orresponding interface zones t o wall. However, you ma y want to use the Copy Zone BC event to set an y boundar y conditions tha t are not the default c onditions tha t ANSY S Fluen t assumes . 11.6.8.2.8. Changing the Motion A ttribut e of a D ynamic Z one To change the motion a ttribut e of a d ynamic z one dur ing y our in-c ylinder c alcula tion, selec t Change Motion A ttribut e in the Type drop-do wn list in the Define E vent Dialog Box (p.3585 ) (Figur e 11.77: The Define E vent Dialog Box (p.1338 )). Selec t the Attribut e (smo othing or remeshing ) and set the appr o- priate Status (enable or disable ). Selec t the c orresponding d ynamic z ones f or which y ou w ant to change the motion a ttribut es in the Dynamic Z ones list. The smo othing attribut e is used t o enable or disable smo othing of no des on selec ted def orming face zones and the remeshing attribut e is used t o enable and disable fac e remeshing on selec ted deforming fac e zones . 11.6.8.2.9. Changing the Time St ep To change the time st ep a t some p oint dur ing the simula tion, selec t Change Time S tep S ize in the Type drop-do wn list in the Define E vent Dialog Box (p.3585 ). Specify the new ph ysical time st ep siz e by en tering the new Time S tep S ize in sec onds . For in-c ylinder simula tions , specify the new ph ysical time st ep b y en tering the new Crank A ngle Step S ize value in degr ees.The ph ysical time st ep is c alcula ted fr om (11.31) 11.6.8.2.10. Changing the Under -Relaxation F actor To change one or mor e under-r elaxa tion fac tors, selec t Change U nder-Relaxa tion F actor in the Type drop-do wn list in the Define E vent Dialog Box (p.3585 ) (Figur e 11.77: The D efine E vent Dialog Box (p.1338 )). Selec t the under-r elaxa tion fac tor tha t you w ant to change , and assign a new v alue t o it in the Under-Relaxa tion F actors list. For mor e inf ormation on setting under-r elaxa tion fac tors, see Setting U nder-R elaxa tion F actors (p.2573 ). 11.6.8.2.11. Inser ting a B oundar y Zone L ayer To inser t a new c ell z one la yer as a separ ate cell z one adjac ent to a b oundar y, selec t Inser t Boundar y Zone L ayer in the Type drop-do wn list in the Define E vent Dialog Box (p.3585 ). Specify the Base Dynamic Z one , from which the la yer of c ells is t o be created, and the Side D ynamic Z one , which represen ts the def orming fac e zone adjac ent to the Base D ynamic Z one before the la yer is inser ted. The new c ell z one will inher it the b oundar y conditions of the c ell z one adjac ent to the Base D ynamic Zone before the la yer is inser ted. Note tha t a new c ell la yer can b e inser ted only fr om a one-sided Base D ynamic Z one .You c annot inser t a new c ell la yer fr om an in terior fac e zone . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1342Modeling F lows Using S liding and D ynamic M eshesFigur e 11.80: Boundar y Zone B efore Inser tion (p.1343 ) and Figur e 11.81: Boundar y Zone A fter Inser- tion (p.1343 ) illustr ate the inser tion of a b oundar y zone la yer. In b oth figur es, the cir cular fac e at the top of the c ylinder is the base d ynamic z one . Figur e 11.80: Boundar y Zone B efore Inser tion Figur e 11.81: Boundar y Zone A fter Inser tion 11.6.8.2.12. Remo ving a B oundar y Zone L ayer To remo ve the c ell z one la yer inser ted using the Inser t Boundar y Zone L ayer event, selec t Remo ve Boundar y Zone L ayer in the Type drop-do wn list in the Define E vent Dialog Box (p.3585 ). Specify the same Base D ynamic Z one tha t you used when y ou defined the inser t boundar y layer e vent. Note tha t a c ell la yer can b e remo ved only fr om a one-sided Base D ynamic Z one . 11.6.8.2.13. Inser ting an Int erior Z one L ayer To inser t a new z one la yer as a separ ate cell z one adjac ent to the in ternal side of a b oundar y, selec t Inser t In terior Z one L ayer in the Type drop-do wn list in the Define E vent Dialog Box (p.3585 ). Specify the Base D ynamic Z one and the Side D ynamic Z one as descr ibed in the Inser t Boundar y Zone Layer event.You also must sp ecify the names of the new in terior fac e zones ( Internal Z one 1 N ame and Internal Z one 2 N ame ) tha t will b e created af ter the c ell z one la yer is cr eated b y ANSY S Fluen t. ANSY S Fluen t inser ts the in terior c ell la yer b y splitting the c ell z one adjac ent to the Base D ynamic Zone with a plane .The p osition of the plane and the nor mal dir ection of the plane ar e implicitly defined b y the c ylinder or igin and c ylinder axis of the Side D ynamic Z one . Figur e 11.82: Interior Z one B efore Inser tion (p.1344 ) and Figur e 11.83: Interior Z one A fter Inser tion (p.1344 ) illustr ate the inser tion of an in terior z one la yer. 1343Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshesFigur e 11.82: Interior Z one B efore Inser tion Figur e 11.83: Interior Z one A fter Inser tion 11.6.8.2.14. Remo ving an Int erior Z one L ayer To remo ve the z one la yer inser ted using the Inser t In terior Z one L ayer event, selec t Remo ve In- terior Z one L ayer in the Type drop-do wn list in the Define E vent Dialog Box (p.3585 ). Specify the same Internal Z one 1 N ame and Internal Z one 2 N ame tha t you used t o define the Inser t In terior Zone L ayer event. 11.6.8.2.15. Inser ting a C ell L ayer To manually inser t a new c ell la yer to the e xisting c ell z one , selec t Inser t Cell L ayer in the Type drop-do wn list in the Define E vent Dialog Box (p.3585 ). Specify the Adjac ent Dynamic F ace Zone and the Direction P aramet er.This c an only w ork on z ones tha t are suit ed f or la yering (see Applic- abilit y of the D ynamic La yering M etho d (p.1288 )). 11.6.8.2.16. Remo ving a C ell L ayer To manually r emo ve a c ell la yer fr om an e xisting c ell z one , selec t Remo ve Cell L ayer in the Type drop-do wn list in the Define E vent Dialog Box (p.3585 ). Specify the Adjac ent Dynamic F ace Zone Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1344Modeling F lows Using S liding and D ynamic M eshesand the Direction P aramet er.This c an only w ork on z ones tha t are suit ed f or la yering (see Applic- abilit y of the D ynamic La yering M etho d (p.1288 )). 11.6.8.2.17. Executing a C ommand To execut e a c ommand , selec t Execut e Command in the Type drop-do wn list in the Define E vent Dialog Box (p.3585 ) (Figur e 11.77: The D efine E vent Dialog Box (p.1338 )). A c ommand c an b e a ser ies of text or Scheme c ommands , or a macr o you ha ve defined (or will define) using the Define M acro Dialog Box (p.3638 ) (see Defining M acros (p.2662 )). Enter the ser ies of c ommands or the name of the macr o in the Command text-en try box. Imp ortant If the c ommand t o be execut ed in volves sa ving a file , see Saving F iles D uring the C alcu- lation (p.2664 ) for imp ortant inf ormation. 11.6.8.2.18. Replacing the Mesh To replac e the mesh and in terpolate existing da ta on to the new mesh dur ing y our simula tion, selec t Replac e M esh from the Type drop-do wn list in the Define E vent dialo g box (Figur e 11.77: The Define E vent Dialog Box (p.1338 )).Then, specify the r eplac emen t mesh under Mesh F ile. Enable In- terpolate D ata A cross Z ones if nec essar y (see Replacing the M esh (p.819) for details). 11.6.8.2.19. Resetting Iner t EGR To convert bur nt gases a t the end of the c ycle t o iner t for the ne xt cycle, selec t Iner t EGR Reset from the Type drop-do wn list in the Define E vent dialo g box (Figur e 11.77: The D efine E vent Dialog Box (p.1338 )). Specify the Zone(s) . For fur ther details , see Resetting Iner t EGR (p.1737 ). 11.6.8.2.20. Diesel Unst eady F lamelet R eset To simula te multiple-c ycle in ternal c ombustion engines using diesel unst eady flamelets , selec t Diesel U nstead y Flamelet Reset from the Type drop-do wn list in the Define E vent dialo g box (Figur e 11.77: The D efine E vent Dialog Box (p.1338 )). Specify the Zone(s) .This e vent is only applic able to and a vailable with diesel unst eady flamelets with t wo or mor e flamelets . For fur ther details , see Resetting D iesel U nsteady Flamelets (p.1702 ). Note tha t Diesel U nstead y Flamelet Reset is gener ally preferable t o Iner t EGR Reset sinc e an additional tr ansp ort equa tion is a voided . 11.6.8.3. Exporting and Imp orting E vents If you w ant to sa ve the e vents you ha ve defined t o a file , click Write... in the Dynamic M esh E vents Dialog Box (p.3584 ) and sp ecify the Event File in The S elec t File D ialog Box (p.569). To read the e vents back in to ANSY S Fluen t, click Read ... in the Dynamic M esh E vents D ialog Box (p.3584 ) and sp ecify the Event File in The S elec t File D ialog Box (p.569). 11.6.9. Specifying the M otion of D ynamic Z ones You must define the motion of the d ynamic z ones in y our mo del. If the z one is a r igid b ody, you c an use a pr ofile or user-defined func tion (UDF) t o define the motion of the r igid b ody or use the six DOF solv er. If the z one is a def orming z one , you c an define the geometr y and the par amet ers tha t control the fac e or z one r emeshing , if applic able . For a z one tha t is def orming and mo ving a t the same time , 1345Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshesyou c an use a user-defined func tion t o define the geometr y and motion of the z one as the y change with time . 11.6.9.1. Gener al P rocedur e You will sp ecify the motion of the d ynamic z ones in y our mo del using the Dynamic M esh Z ones dialo g box Setup → Dynamic M esh → Create/Edit... Details ab out sp ecifying diff erent types of motion ar e pr ovided in this sec tion. 11.6.9.1.1. Creating a D ynamic Z one When y ou ha ve complet ed the sp ecific ation of a d ynamic z one , click Create in the Dynamic M esh Zones D ialog Box (p.3587 ) to complet e the sp ecific ation and add the z one t o the Dynamic M esh Zones list. 11.6.9.1.2. Mo difying a D ynamic Z one If you w ant to mak e a change t o the sp ecific ation of a d ynamic z one , selec t the z one in the Dynamic Mesh Z ones list, change the sp ecific ation, and then click Create in the Dynamic M esh Z ones D ialog Box (p.3587 ) to up date the sp ecific ation. 11.6.9.1.3. Check ing the C ent er of Gr avity If a d ynamic z one has solid b ody motion, you c an view its cur rent position and or ientation of the center of gr avity (with r espect to initial da ta) b y selec ting the z one in the Dynamic M esh Z ones list and viewing the v alues under Center of G ravity Location and Rigid B ody Or ientation . 11.6.9.1.4. Deleting a D ynamic Z one To delet e a d ynamic z one tha t you ha ve sp ecified , selec t the z one in the Dynamic M esh Z ones list, and click Delet e or Delet e All.The z one or z ones will b e remo ved fr om the Dynamic M esh Z ones list. 11.6.9.2. Stationar y Zones By default , if no motion (mo ving or def orming) a ttribut es ar e assigned t o a fac e or c ell z one , then the z one is not c onsider ed when up dating the mesh t o the ne xt time st ep. However, ther e ar e cases wher e an e xplicit declar ation of a sta tionar y zone is r equir ed. For e xample , if a c ell z one is assigned some solid b ody motion, the p ositions of all no des b elonging t o the c ell z one will b e up dated e ven though some of the no des ma y also b e par t of a non-mo ving b oundar y zone . An explicit declar ation of a sta tionar y zone e xcludes the no des on these z ones when up dating the no de p ositions . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1346Modeling F lows Using S liding and D ynamic M eshesFigur e 11.84: The D ynamic M esh Z ones D ialo g Box for a S tationar y Zone To define a sta tionar y zone in y our mo del, follow the st eps b elow. 1.Selec t the sta tionar y zone in the Zone N ames drop-do wn list. 2.Selec t Stationar y under Type. 3.If the sta tionar y zone is a fac e zone tha t is not a b oundar y of a C utCell d ynamic c ell z one , then define the Cell H eigh t in the Meshing Options tab f or an y Adjac ent Zone tha t is in volved in lo cal remeshing or d ynamic la yering.The Cell H eigh t specifies the ideal heigh t ( in Equa tion 11.15 (p.1286 ) and Equa tion 11.16 (p.1287 ) of the adjac ent cells. Make a selec tion in the Cell H eigh t drop-do wn menu t o specify this v alue as either a constan t or a c ompiled user-defined func tion. If you selec t the constan t option, enter a v alue in the Cell H eigh t text-en try box. If you cho ose t o use a c ompiled user-defined func tion t o define an ideal c ell heigh t tha t varies as a func tion of time or cr ank angle , you must first define a DEFINE_DYNAMIC_ZONE_PROPERTY UDF . After y ou ha ve compiled the UDF sour ce file , built a shar ed libr ary, and loaded it in to ANSY S Fluen t, the name of the UDF libr ary will b e available f or selec tion in the Cell H eigh t drop-do wn list. Refer to the Fluen t Customiza tion M anual for inf ormation ab out UDFs . 4.If the sta tionar y zone is a b oundar y of a C utCell d ynamic c ell z one (this is aut oma tically det ected if the CutCell d ynamic c ell z one is cr eated first), then en ter values f or the Maximum M esh S ize and Growth Rate in the Meshing Options tab . If you ha ve enabled Infla tion L ayers for the c ell z one , then y ou will 1347Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshesalso ha ve the option t o enable Zonal Infla tion L ayer C ontrol on the b oundar y zone and sp ecify lo cal infla tion settings in the Infla tion S ettings dialo g box (using the Settings ... butt on). See Figur e 11.85: The Dynamic M esh Z ones D ialog Box for a C utCell B oundar y Zone (p.1349 ) for an e xample of the Dynamic Mesh Z ones dialo g box with the Meshing Options tab as it app ears f or C utCell b oundar y zones . (The same meshing input is r equir ed a t all C utCell b oundar y zones , whether the motion t ype is Stationar y, Rigid B ody,Deforming , or User-D efined .) Two diff erent siz e func tions ar e available t o control the lo cal mesh r efinemen t: •soft siz e func tion For this siz e func tion, the C artesian mesh is lo cally r efined such tha t the r esulting mesh size is smaller or equal t o the Maximum M esh S ize specified . •mesh-based siz e func tion For this siz e func tion, the C artesian mesh is lo cally r efined such tha t the r esulting mesh size is lo cally of the same siz e as the input mesh pr ovided . The swit ch b etween using the sof t or the mesh-based siz e func tion dep ends on the v alue en tered for the Maximum M esh S ize. A v alue of 0 specifies tha t the mesh-based siz e func tion is used . If a positiv e value is en tered, then the sof t siz e-func tion is used and the v alue en tered lo cally limits the mesh siz e.The Growth R ate controls the r ate at which the C artesian mesh gr ows away from the b oundar y.The maximum C artesian mesh siz e obtained in the c ell z one is alw ays controlled by the sp ecified Maximum M esh S ize for the C utCell c ell z one . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1348Modeling F lows Using S liding and D ynamic M eshesFigur e 11.85: The D ynamic M esh Z ones D ialo g Box for a C utC ell B oundar y Zone You c an view the vital sta tistics of y our z one b y click ing on the Zone Sc ale Inf o… butt on.This opens the Zone Sc ale Inf o Dialog Box (p.3597 ), wher e you c an view the minimum, maximum, and average length sc ale v alues , as w ell as the maximum sk ewness v alue . 5.For cases with str ong fluid-str ucture interaction, solution stabiliza tion ma y help c onvergenc e for boundar y zones . Solution stabiliza tion c an b e set in the Solver Options tab . See Solution S tabiliza tion for D ynamic M esh B oundar y Zones (p.1364 ) for details . 6.Click Create. Note tha t if y ou sp ecify infla tion la yer par amet ers in the Infla tion S ettings dialo g box, these settings ar e not sa ved un til you cr eate or up date the d ynamic z one . 11.6.9.3. Rigid B ody Motion To define a r igid-b ody zone in y our mo del, follow the st eps b elow. 1349Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshesFigur e 11.86: The D ynamic M esh Z ones D ialo g Box for a R igid B ody M otion 1.Selec t the r igid b ody zone in the Zone N ames drop-do wn list. 2.Selec t the Rigid B ody option under Type. 3.If you w ant to sp ecify the motion of the r igid b ody zone using a pr ofile or user-defined func tion, then selec t a pr ofile or user-defined func tion fr om the Motion UDF/P rofile drop-do wn list in the Motion Attribut es tab . See Profiles (p.1051 ) and Solid-B ody Kinema tics (p.1365 ) for inf ormation on pr ofiles , and see the Fluen t Customiza tion M anual for inf ormation on user-defined func tions . 4.If you enabled the In-C ylinder option in the Dynamic M esh Task P age (p.3567 ), ANSY S Fluen t provides built-in func tions in the Motion UDF/P rofile drop-do wn list tha t can b e useful f or defining the r igid body motion of a pist on. If you w ould lik e the motion of the pist on t o be a func tion of cr ank angle (tha t is, governed b y Equa tion 11.25 (p.1315 )), then y ou should selec t **pist on-full** . For fur ther inf ormation, see In-C ylinder S ettings (p.1313 ). 5.If you enabled the Six DOF option in the Dynamic M esh Task P age (p.3567 ), mak e sur e tha t On is enabled in the Six DOF group b ox in the Motion A ttribut es tab (see Figur e 11.88: The D ynamic M esh Z ones Dialog Box for a R igid B ody Motion U sing the S ix DOF S olver (p.1353 )), to ensur e tha t the six DOF solv er Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1350Modeling F lows Using S liding and D ynamic M eshesis being used .Then mak e a selec tion fr om the Six DOF UDF/P roperties drop-do wn list; for details on creating the selec tions a vailable in this list ,Setting R igid B ody Motion A ttribut es for the S ix DOF S olv- er (p.1330 ). Note tha t the Passiv e option in the Six DOF group b ox is used when y ou do not w ant the f orces and momen ts on the z one t o be tak en in to consider ation. 6.Specify the initial lo cation of the c enter of gr avity for the r igid b ody by en tering c oordina tes in the Center of G ravity Location group b ox. 7.If you w ant a r igid b ody to mo ve relative to another r igid b ody, then y ou must enable Rela tive M otion and sp ecify the Rela tive Zone . Note You must cr eate the r elative rigid b ody zone b efore creating a r igid b ody tha t is de- penden t on tha t zone , if y ou ar e setting up the motion using the gr aphic al user in terface (GUI). The or der in which y ou sp ecify the z ones do es not ma tter if y ou set up the motion using the t ext user in terface (TUI). 8.Specify the or ientation of the r igid b ody (in the iner tial c oordina te sy stem) b y en tering the or ientations of the r igid b ody in Rigid B ody Or ientation . Together , the Rigid B ody Or ientation and the Center of G ravity Location are the lo cal referenc e frame that y ou c an cho ose t o use f or y our user -defined func tion (UDF) or set of six DOF pr operties that descr ibes the motion of the r igid b ody. For additional inf ormation ab out cr eating UDFs f or solid-b ody kinematics , see DEFINE_CG_MOTION in the Fluent C ustomization Manual ; for details on cr eating UDFs / pr operties f or the six DOF sol ver, see Setting R igid B ody Motion A ttribut es f or the S ix DOF Solver (p.1330 ). For most c ases , this is an initial r eference or ientation tha t ANSY S Fluen t later up dates, letting y ou keep tr ack of the objec t’s cur rent orientation. The r igid b ody or ientation is most useful when using the six DOF solv er, wher e it is used t o comput e the tr ansf ormation ma trices (Six DOF S olver Theor y in the Theor y Guide ). If needed , you c an use the Orientation C alcula tor to convert a r otation ma trix or E uler angles into the r equir ed axis and angle inputs .You c an also use this c alcula tor if y ou k now the r otations the r igid b ody will e xperienc e, but do not k now its final or ientation. 1351Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshesFigur e 11.87: Orientation C alcula tor D ialo g Box To use the Orientation C alcula tor: a.Enter a v alue , either in Axis and A ngle ,Rota tion M atrix, or Euler A ngle format, and click Evalua te to see the v alue in the output f ormat. The c alculat or also c onverts the ent ered v alues int o the other t wo “grayed-out ” input f ormats . Note There ar e se veral p ossible E uler angle r epresen tations . Fluen t uses a v ector defined by , , and wher e: is the r otation ab out the or iginal Z axis , is the r otation about the r otated Y axis , and is the r otation ab out the r otated X axis . b.Enable Conc atena te Next Input if you w ant the ne xt input t o be concatenated t o the pr evious output. c.Click Fill to use the cur rent Output as y our Rigid B ody Or ientation in the Dynamic M esh Z ones dialo g box. 9.When using the six DOF solv er, specify the v elocity of the c enter of gr avity with r espect to the iner tia coordina te sy stem b y en tering the v elocity of the c enter of gr avity in Center of G ravity Velocity. Also, specify the angular v elocity of the r igid b ody with r espect to the iner tia c oordina te sy stem b y en tering the angular v elocity of the r igid b ody in Rigid B ody Angular Velocity. Note tha t these fields ar e ignor ed for one DOF r otation and tr ansla tion, respectively. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1352Modeling F lows Using S liding and D ynamic M eshesFigur e 11.88: The D ynamic M esh Z ones D ialo g Box for a R igid B ody M otion U sing the S ix DOF S olver 10.If you ar e solving an in-c ylinder pr oblem, specify the dir ection of the r eference axis of the v alves or pist on in Valve/Piston A xis. The cur rent valve lift or pist on str oke is aut oma tically up dated in Lift/Stroke when y ou click Create based on the par amet ers y ou ha ve sp ecified ear lier when y ou first in voke the in-c ylinder option. 11.By default , the b oundar y mesh motion is tak en in to consider ation when imp osing the ph ysical boundar y conditions , even if the b oundar y mo ves b ecause of a mo ving adjac ent cell z one and no d ynamic z one has b een cr eated f or the b oundar y. If this is not the desir ed b ehavior, and if y ou w ould lik e to exclude the mesh motion fr om c ontributing t o the b oundar y conditions , then y ou need t o enable the Exclude Mesh M otion in B oundar y Conditions option f or tha t zone . 1353Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshes12.If the r igid b ody zone is a fac e zone tha t is not a b oundar y of a C utCell d ynamic c ell z one , specify the Cell H eigh t for each Adjac ent Zone in the Meshing Options tab .The Cell H eigh t is the ideal c ell heigh t ( in Equa tion 11.15 (p.1286 ) and Equa tion 11.16 (p.1287 ) tha t is used b y ANSY S Fluen t to det ermine when the pr isma tic la yer ne xt to the r igid b ody should b e split or mer ged with the la yer ne xt to it. If the adjac ent zone is t etrahedr al or tr iangular , the ideal heigh t is used b y ANSY S Fluen t to det ermine if adjac ent cells must b e agglomer ated f or lo cal remeshing . Make a selec tion in the Cell H eigh t drop-do wn menu to sp ecify this v alue as either a constan t or a c ompiled user-defined func tion. If you selec t the constan t option, enter a v alue in the Cell H eigh t text-en try box. If you cho ose t o use a c ompiled user-defined func tion t o define an ideal c ell heigh t tha t varies as a func tion of time or cr ank angle , you must first define a DEFINE_DYNAMIC_ZONE_PROPERTY UDF . After y ou ha ve compiled the UDF sour ce file , built a shar ed libr ary, and loaded it in to ANSY S Fluen t, the name of the UDF libr ary will b e available f or selec tion in the Cell H eigh t drop-do wn list. Refer to the Fluen t Customiza tion M anual for inf ormation ab out UDFs . 13.If the r igid b ody zone is a b oundar y of a C utCell d ynamic c ell z one (this is aut oma tically det ected if the CutCell d ynamic c ell z one is cr eated first), then en ter values f or the Maximum M esh S ize and Growth Rate in the Meshing Options tab , as descr ibed in st ep 4 of Stationar y Zones (p.1346 ). If you ha ve enabled Infla tion L ayers for the c ell z one , then y ou will also ha ve the option t o enable Zonal Infla tion L ayer Control on the b oundar y zone and sp ecify lo cal infla tion settings in the Infla tion S ettings dialo g box (using the Settings ... butt on). 14.If the d ynamic z one is a fac e zone with an adjac ent boundar y layer mesh, you must apply b oundar y layer smo othing using the Deform A djac ent Boundar y Layer with Z one option in the Meshing Options tab if y ou w ant the b oundar y layer to mo ve with the mo ving fac e zone . For e xample , this option is ne- cessar y if y ou ar e applying fac e region r emeshing with pr ism la yers and y ou ha ve not dec omp osed the mesh v olume (see Face Region R emeshing with Wedge C ells in P rism La yers (p.1301 )). In such cir cumstanc es, the Deform A djac ent Boundar y Layer with Z one option ensur es tha t the base pr ism elemen ts sho wn in Figur e 11.44: Volume D ecomp osition f or the B ase of the P rism La yers (p.1303 ) will mo ve rigidly with the pist on. Note tha t the b oundar y layer smo othing metho d is pr imar ily in tended f or tr ansla tional motion of the fac e zone . If signific ant rotation is applied t o the fac e zone , the b oundar y layer cells ma y be- come sk ewed. For mor e inf ormation r efer to Boundar y La yer S moothing M etho d (p.1282 ). 15.For cases with str ong fluid-str ucture interaction, solution stabiliza tion ma y be nec essar y for b oundar y zones if the use of implicit mesh up dating (descr ibed in Implicit U pdate Settings (p.1332 )) is insufficien t to stabiliz e the solv er due t o the fluid motion. Solution stabiliza tion options c an b e set in the Solver Options tab . See Solution S tabiliza tion f or D ynamic M esh B oundar y Zones (p.1364 ) for details . 16.Click Create. 11.6.9.4. Deforming Motion To define a def orming z one in y our mo del, follow the st eps b elow. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1354Modeling F lows Using S liding and D ynamic M eshesFigur e 11.89: The D ynamic M esh Z ones D ialo g Box for a D eforming M otion with C ell Z one Options 1.Selec t the def orming z one in the Zone N ames drop-do wn list. 2.Selec t the Deforming option under Type. 3.Specify the geometr y of the def orming z one in the Geometr y Definition tab . •If no geometr y is a vailable , selec t faceted in the Definition drop-do wn list. •If the geometr y is a plane , selec t plane in the Definition drop-do wn list. To define the plane , enter the p osition of a p oint on the plane in Point on P lane and the plane nor mal in Plane N ormal . •If the geometr y is a c ylinder , selec t cylinder in the Definition drop-do wn list. To define the c ylinder , enter the Cylinder R adius , the Cylinder Or igin and the Cylinder A xis. 1355Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshes•If the geometr y is unsp ecified and mesh motion nor mal t o the b oundar y is p ermissible , selec t unsp e- cified in the Definition drop-do wn list. This option is only a vailable if the linear ly elastic solid mesh smo othing metho d is enabled ( Linear ly Elastic S olid B ased S moothing M etho d (p.1279 )). •If the geometr y is descr ibed b y a user-defined func tion, selec t user-defined in the Definition drop- down list and the appr opriate user-defined func tions in the Geometr y UDF drop-do wn list. See the Fluen t Customiza tion M anual for inf ormation on user-defined func tions . For 3D simula tions , ANSY S Fluen t allo ws you t o pr eser ve features on the b oundar y zones tha t are imp ortant for the flo w. Such f eatures ma y be at the junc ture of diff erent boundar y zones , or the y may be on a single non-planar b oundar y zone . For an y geometr y definition ( faceted,plane ,cyl- inder , or user-defined ), you c an indic ate whether y ou w ant to pr eser ve features of a sp ecific angular r ange b y enabling Feature D etection under Feature Options and setting a thr eshold value f or the Feature Angle in degr ees. For mor e inf ormation (including ho w the Feature Angle is defined), see Feature Detection (p.1313 ). When a vailable , the geometr y inf ormation is used t o pr ojec t no des on the def orming z one af ter remeshing the fac e zone , or if no des ar e mo ved thr ough smo othing . 4.For def orming b oundar y and c ell z ones tha t are not C utCell z ones , specify the appr opriate remeshing par amet ers in the Meshing Options tab . •You c an lo cally enable Remeshing and define the settings in the gr oup b ox under this option, including the f ollowing: Under Paramet ers, enabling the Global S ettings option ensur es tha t settings defined in the Mesh M etho d Settings D ialog Box (p.3570 ) are used f or this d ynamic z one . Disabling this option allows you t o revise the Minimum L ength Sc ale,Maximum L ength Sc ale and/or Maximum Skewness locally.When setting these v alues , you should use the vital sta tistics of y our z one found in the Zone Sc ale Inf o Dialog Box (p.3597 ), which c an b e op ened b y click ing the Zone Scale Inf o... butt on. For b oundar y zones , under Options you c an sp ecify the r emeshing metho ds applied t o this dynamic z one , including Region and Local. •You c an lo cally enable Smoothing and , if Spring/L aplac e/Boundar y Layer is selec ted f or smo othing in the Mesh M etho d Settings D ialog Box (p.3570 ), define the settings in the gr oup b ox under this option, including the f ollowing: If you selec ted a c ell z one , enabling the Global S ettings option ensur es tha t the elemen t type defined in the Mesh S moothing P aramet ers D ialog Box (p.3573 ) is used f or this d ynamic z one . Disabling it allo ws you t o selec t a diff erent elemen t type lo cally. If you selec ted a b oundar y zone , you c an sp ecify whether the smo othing metho d is spr ing based or Laplacian. 5.To sp ecify tha t a def orming c ell z one is r emeshed using the C utCell z one metho d, ensur e tha t Remeshing is enabled in the Meshing Options tab , and enable the CutC ell option under Options (see Figur e 11.90: The D ynamic M esh Z ones D ialog Box for a D eforming C utCell C ell Z one (p.1357 )). Note tha t this option is only a vailable if y ou ha ve pr eviously enabled the CutC ell Z one option in the Remeshing tab of the Mesh M etho d Settings dialo g box (see Figur e 11.34: The R emeshing Tab in the M esh M etho d Settings D ialog Box (p.1291 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1356Modeling F lows Using S liding and D ynamic M eshesFigur e 11.90: The D ynamic M esh Z ones D ialo g Box for a D eforming C utC ell C ell Z one After the CutC ell option has b een enabled , you must en ter v alues f or the global C utCell par amet ers Maximum M esh S ize and Growth R ate, as w ell as the c ontrols f or the r emeshing fr equenc y, Minimum Or tho gonal Q ualit y and Remeshing In terval.You also ha ve the option t o enable In- flation L ayers for the c ell z one and sp ecify the global infla tion par amet ers in the Infla tion S ettings dialo g box. See Using the C utCell Z one R emeshing M etho d (p.1306 ) for mor e inf ormation ab out adding infla tion la yers t o a C utCell mesh. The Maximum M esh S ize specified f or the C utCell c ell z one c ontrols the global maximum siz e of the C artesian c ells.The global Growth R ate is used f or all mesh-based siz e func tions applied to CutCell b oundar y zones tha t are not defined as d ynamic z ones .When selec ting v alues f or these controls, it ma y be helpful t o view the sta tistics of y our c ell z one b y click ing on the Zone Sc ale 1357Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshesInfo... butt on.This op ens the Zone Sc ale Inf o Dialog Box (p.3597 ), wher e you c an view the minimum and maximum length sc ale v alues , as w ell as the maximum sk ewness v alues . The C utCell r emeshing is p erformed aut oma tically whene ver cells e xhibit an or thogonal qualit y (as defined in Mesh Q ualit y (p.719)) tha t is less than the sp ecified Minimum Or tho gonal Q ualit y. The r emeshing is also p erformed p eriodically af ter the c alcula tion has under gone the numb er of time st eps y ou sp ecified f or the Remeshing In terval. Click the Boundar y Zones Inf o... butt on t o op en the CutC ell B oundar y Zones Inf o dialo g box (Figur e 11.91: The C utCell B oundar y Zones Inf o Dialog Box (p.1358 )).This dialo g box lists all the boundar y zones asso ciated with the C utCell c ell z one , along with the asso ciated siz e func tions and z onal meshing par amet ers.The infla tion la yer settings used on all b oundar ies ar e also sho wn. It is r ecommended tha t you r evisit this dialo g box after y ou ha ve created all of the d ynamic z ones , in or der t o review all of the par amet ers y ou ha ve set. Figur e 11.91: The C utC ell B oundar y Zones Inf o D ialo g Box You c an also enable lo cal Smoothing and r evise the asso ciated settings , as descr ibed pr eviously for def orming z ones tha t are not C utCell z ones . 6.If the def orming z one is a b oundar y of a C utCell d ynamic c ell z one (this is aut oma tically det ected if the CutCell d ynamic c ell z one is cr eated first), then en ter values f or the Maximum M esh S ize and Growth Rate in the Meshing Options tab , as descr ibed in st ep 4. of Stationar y Zones (p.1346 ). If you ha ve enabled Infla tion L ayers for the c ell z one , then y ou will also ha ve the option t o enable Zonal Infla tion L ayer Control on the b oundar y zone and sp ecify lo cal infla tion settings in the Infla tion S ettings dialo g box (using the Settings ... butt on). 7.For cases with str ong fluid-str ucture interaction, solution stabiliza tion ma y help c onvergenc e for boundar y zones . Solution stabiliza tion c an b e set in the Solver Options tab . See Solution S tabiliza tion for D ynamic M esh B oundar y Zones (p.1364 ) for details . 8.Click Create. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1358Modeling F lows Using S liding and D ynamic M eshes11.6.9.5. User -Defined Motion For a z one tha t is def orming and/or mo ving , you c an define the p osition of each no de on the gener al deforming / mo ving z one using a user-defined func tion (UDF). To define a mo ving / def orming z one , follow the st eps b elow. 1.Selec t the mo ving and def orming z one in the Zone N ames drop-do wn list. 2.Selec t the User-D efined option under Type. 3.In the Motion A ttribut es tab , selec t the user-defined func tion tha t defines the geometr y and motion of the z one fr om the Mesh M otion UDF drop-do wn list. See the Fluen t Customiza tion M anual for inf orm- ation on user-defined func tions used t o sp ecify user-defined motion. 4.By default , the b oundar y mesh motion is tak en in to consider ation when imp osing the ph ysical boundar y conditions . If this b ehavior is not desir ed and y ou w ould inst ead lik e to exclude the mesh motion fr om c ontributing t o the b oundar y conditions , then y ou need t o enable the Exclude Mesh M otion in B oundar y Conditions option f or tha t boundar y zone .The f ollowing ar e examples of when y ou migh t want to exclude such motion: •You ha ve created a d ynamic z one f or a c ell z one tha t mo ves, but one or mor e of the b oundar ies of that cell z one should b e treated as sta tionar y. •You ar e using a DEFINE_GRID_MOTION UDF tha t defines no dal motion on a b oundar y tha t, for e x- ample , includes b oth r igid b ody motion (which should c ontribut e to the b oundar y condition) and smo othing (which should not). With such UDFs , you must p erform the f ollowing st eps f or tha t boundar y: –Enable the Exclude M esh M otion in B oundar y Conditions option. –Define the r igid b ody motion in the Momen tum tab of the Wall dialo g box. 5.If you w ant the mo vemen t / def ormation t o be relative to the r igid b ody motion of a c ell z one , then y ou can enable Rela tive M otion and selec t the c ell z one fr om the Rela tive Zone list. Note You must sp ecify the mo vemen t / def ormation in y our UDF using NODE_COORD_NEST , rather than sp ecify the final c oordina tes (as y ou w ould if y ou w ere NO T sp ecifying it relative to a c ell z one). For additional inf ormation, see DEFINE_GRID_MOTION in the Fluent C ustomization Manual . You must cr eate the r elative rigid b ody zone b efore creating the user-defined z one if you ar e setting up the z ones using the gr aphic al user in terface (GUI). The or der in which you cr eate the z ones do es not ma tter if y ou set up the z ones using the t ext user in ter- face (TUI). 6.For a fac e zone tha t is not a b oundar y of a C utCell d ynamic c ell z one , you c an sp ecify the Cell H eigh t in the Meshing Options tab f or an y Adjac ent Zone tha t is in volved in lo cal remeshing or d ynamic la yering. The Cell H eigh t specifies the ideal heigh t ( in Equa tion 11.15 (p.1286 ) and Equa tion 11.16 (p.1287 ) of the adjac ent cells. Make a selec tion in the Cell H eigh t drop-do wn menu t o sp ecify this v alue as either a constan t or a c ompiled user-defined func tion. 1359Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshesIf you selec t the constan t option, enter a v alue in the Cell H eigh t text-en try box. If you cho ose t o use a c ompiled user-defined func tion t o define an ideal c ell heigh t tha t varies as a func tion of time or cr ank angle , you must first define a DEFINE_DYNAMIC_ZONE_PROPERTY UDF . After y ou ha ve compiled the UDF sour ce file , built a shar ed libr ary, and loaded it in to ANSY S Fluen t, the name of the UDF libr ary will b e available f or selec tion in the Cell H eigh t drop-do wn list. Refer to the separ ate Fluen t Customiza tion M anual for inf ormation ab out UDFs . 7.If the fac e zone is a b oundar y of a C utCell d ynamic c ell z one (this is aut oma tically det ected if the C utCell dynamic c ell z one is cr eated first), then en ter values f or the Maximum M esh S ize and Growth R ate in the Meshing Options tab , as descr ibed in st ep 4 of Stationar y Zones (p.1346 ). If you ha ve enabled Infla tion Layers for the c ell z one , then y ou will also ha ve the option t o enable Zonal Infla tion L ayer C ontrol on the b oundar y zone and sp ecify lo cal infla tion settings in the Infla tion S ettings dialo g box (using the Settings ... butt on). 8.If the d ynamic z one is a fac e zone with an adjac ent boundar y layer mesh, and y ou w ant to use the boundar y layer smo othing metho d (as descr ibed in Boundar y La yer Smoothing M etho d (p.1282 )), enable the Deform A djac ent Boundar y Layer with Z one option in the Meshing Options tab . 9.For a 3D b oundar y zone , you c an allo w lo cal fac e remeshing b y enabling the Local option (under Remeshing M etho ds) in the Meshing Options tab . For details , see Local Face Remeshing M etho d (p.1293 ). Enabling this option allo ws you t o do the f ollowing: •You c an r evise the Maximum S kewness allo wed f or fac es if y ou w ant to sp ecify a lo cal value f or this dynamic z one tha t diff ers fr om the one y ou sp ecified globally in the Mesh M etho d Settings D ialog Box (p.3570 ). Note tha t the global setting ma y still b e used if ANSY S Fluen t det ermines tha t your lo cal setting is unr easonable . •You c an pr eser ve features, not only a t the junc ture of diff erent boundar y zones , but also on a single non-planar b oundar y zone . In the Geometr y Definition tab , you c an indic ate whether y ou w ant to include f eatures of a sp ecific angular r ange b y enabling Feature Detection under Feature Options and setting a thr eshold v alue f or the Feature Angle in degr ees. For mor e inf ormation (including ho w the Feature Angle is defined), see Feature Detection (p.1313 ). 10.For cases with str ong fluid-str ucture interaction, solution stabiliza tion ma y help c onvergenc e for boundar y zones . Solution stabiliza tion c an b e set in the Solver Options tab . See Solution S tabiliza tion for D ynamic M esh B oundar y Zones (p.1364 ) for details . 11.Click Create. 12.If this z one is par t of a mesh in terface and only one side under goes user-defined motion, then b y default that motion will b e transf erred t o the other side in or der t o main tain the c oupling .You c an change the metho d by which the displac emen t of the passiv e no des is c alcula ted or disable this tr ansf er alt ogether , as descr ibed in Transf erring M otion A cross a M esh In terface (p.765). 11.6.9.5.1. Specifying B oundar y Layer D eformation Smo othing For a b oundar y layer tha t def orms acc ording t o the adjac ent fac e zone , the z one tha t is def orming and mo ving is usually defined using a user-defined func tion (UDF), as descr ibed in User-D efined Motion (p.1359 ).To define a mo ving and def orming b oundar y layer, perform the st eps tha t follow. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1360Modeling F lows Using S liding and D ynamic M eshesIf the b oundar y layer b orders a fac e zone tha t is only mo ving and is not def orming , you should consider applying r igid b ody motion t o the fac e zone (see Rigid B ody Motion (p.1349 )) rather than user-defined motion, as r igid b ody motion usually in volves a simpler UDF . 1. Set up the mo ving and def orming z one . a. Selec t the mo ving and def orming z one in the Zone N ames drop-do wn list. b.Selec t User-D efined from the Type list. c.In the Motion A ttribut es tab , selec t the user-defined func tion tha t defines the geometr y and motion of the z one fr om the Mesh M otion UDF drop-do wn list. d.In the Meshing Options tab , enable the Deform A djac ent Boundar y Layer with Z one option. e.Click Create. 2. Set up a def orming d ynamic z one f or the fluid z one tha t contains the b oundar y layer. a. Selec t the fluid z one tha t contains the b oundar y layer fr om the Zone N ames drop-do wn list. b.Selec t Deforming from the Type list. c.In the Meshing Options tab , ensur e tha t Remeshing and Smoothing are enabled . d.Click Create. 3. If the fluid z one set up in the st ep 2 c onsists en tirely of the b oundar y layer elemen ts, set up a def orming dynamic z one f or the neighb oring fluid z one .This st ep is nec essar y because the def orming b oundar y layer will def orm the adjac ent cells. a. Selec t the fluid z one tha t neighb ors the b oundar y layer zone fr om the Zone N ames drop-do wn list. b.Selec t Deforming from Type list. c.In the Meshing Options tab , enable Smoothing and Remeshing in the Metho ds group b ox. d.Click Create. 11.6.9.6. System C oupling Motion For a z one tha t is in volved in a sy stem c oupling , the motion is defined b y the applic ation tha t ANSY S Fluen t is c oupled with on this z one . For mor e details ab out setting up a simula tion with sy stem coupling see Performing S ystem C oupling S imula tions U sing F luen t (p.3207 ) and the System C oupling User's G uide .To define a sy stem c oupling r egion, follow the st eps b elow. 1.Selec t the mo ving and def orming z one in the Zone N ames drop-do wn list. 2.Selec t the System C oupling option under Type. 3.The sy stem c oupling r egion c annot b e a b oundar y of a C utCell d ynamic c ell z one , so y ou c an sp ecify the Cell H eigh t in the Meshing Options tab f or an y Adjac ent Zone tha t is in volved in lo cal remeshing or 1361Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshesdynamic la yering.The Cell H eigh t specifies the ideal heigh t ( in Equa tion 11.15 (p.1286 ) and Equa- tion 11.16 (p.1287 ) of the adjac ent cells. Make a selec tion in the Cell H eigh t drop-do wn menu t o sp ecify this v alue as either a constan t or a c ompiled user-defined func tion. If you selec t the constan t option, enter a v alue in the Cell H eigh t text-en try box. If you cho ose t o use a c ompiled user-defined func tion t o define an ideal c ell heigh t tha t varies as a func tion of time or cr ank angle , you must first define a DEFINE_DYNAMIC_ZONE_PROPERTY UDF . After y ou ha ve compiled the UDF sour ce file , built a shar ed libr ary, and loaded it in to ANSY S Fluen t, the name of the UDF libr ary will b e available f or selec tion in the Cell H eigh t drop-do wn list. Refer to the separ ate Fluen t Customiza tion M anual for inf ormation ab out UDFs . 4.For cases with str ong fluid-str ucture interaction, solution stabiliza tion ma y be nec essar y to achie ve convergenc e for b oundar y zones under going sy stem c oupling motion. Solution stabiliza tion options can b e set in the Solver Options tab . See Solution S tabiliza tion f or D ynamic M esh B oundar y Zones (p.1364 ) for details . 5.Click Create. 6.If this z one is par t of a mesh in terface and only one side under goes sy stem c oupling motion, then b y default tha t motion will b e transf erred t o the other side in or der t o main tain the c oupling .You c an change the metho d by which the displac emen t of the passiv e no des is c alcula ted or disable this tr ansf er alt o- gether , as descr ibed in Transf erring M otion A cross a M esh In terface (p.765). Note If the System C oupling option is enabled , and ANSY S Fluen t is not in volved with a sy stem coupling simula tion, then this z one t ype behaves in the same w ay as a sta tionar y zone . 11.6.9.7. Intrinsic FSI Motion For a t wo-w ay intrinsic fluid-str ucture in teraction (FSI) simula tion, you c an sp ecify tha t a w all z one between a fluid and solid c ell z one def orms acc ording t o the def ormation of the adjac ent solid z one by performing the f ollowing st eps. For mor e details ab out setting up an in trinsic FSI simula tion, see Setting U p an In trinsic F luid-S tructure In teraction (FSI) S imula tion (p.2330 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1362Modeling F lows Using S liding and D ynamic M eshesFigur e 11.92: The D ynamic M esh Z ones D ialo g Box for an In trinsic FSI Z one 1.Selec t a w all z one tha t is b etween a fluid and solid c ell z one in the Zone N ames drop-do wn list. Note that this z one must b e the side of a t wo-sided w all (tha t is, the w all or w all-shado w) tha t is immedia tely adjac ent to the fluid c ell z one (as indic ated b y the Adjac ent Cell Z one field in the Wall dialo g box). 2.Selec t Intrinsic FSI from the Type list. Note tha t this t ype is only a vailable when y ou ha ve selec ted a model in the Structural M odel D ialog Box (p.3378 ). 3.For a fac e zone tha t is not a b oundar y of a C utCell d ynamic c ell z one , you c an sp ecify the Cell H eigh t in the Meshing Options tab f or an y Adjac ent Zone tha t is in volved in lo cal remeshing or d ynamic la yering. The Cell H eigh t specifies the ideal heigh t ( in Equa tion 11.15 (p.1286 ) and Equa tion 11.16 (p.1287 ) of the adjac ent cells. Make a selec tion in the Cell H eigh t drop-do wn menu t o sp ecify this v alue as either a constan t or a c ompiled user-defined func tion. 1363Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshesIf you selec t the constan t option, enter a v alue in the Cell H eigh t text-en try box. If you cho ose t o use a c ompiled user-defined func tion t o define an ideal c ell heigh t tha t varies as a func tion of time or cr ank angle , you must first define a DEFINE_DYNAMIC_ZONE_PROPERTY UDF . After y ou ha ve compiled the UDF sour ce file , built a shar ed libr ary, and loaded it in to ANSY S Fluen t, the name of the UDF libr ary will b e available f or selec tion in the Cell H eigh t drop-do wn list. Refer to the separ ate Fluen t Customiza tion M anual for inf ormation ab out UDFs . 4.If the fac e zone is a b oundar y of a C utCell d ynamic c ell z one (this is aut oma tically det ected if the C utCell dynamic c ell z one is cr eated first), then en ter values f or the Maximum M esh S ize and Growth R ate in the Meshing Options tab , as descr ibed in st ep 4 of Stationar y Zones (p.1346 ). If you ha ve enabled Infla tion Layers for the c ell z one , then y ou will also ha ve the option t o enable Zonal Infla tion L ayer C ontrol on the b oundar y zone and sp ecify lo cal infla tion settings in the Infla tion S ettings dialo g box (using the Settings ... butt on). 5.If the d ynamic z one is a fac e zone with an adjac ent boundar y layer mesh, and y ou w ant to use the boundar y layer smo othing metho d (as descr ibed in Boundar y La yer Smoothing M etho d (p.1282 )), enable the Deform A djac ent Boundar y Layer with Z one option in the Meshing Options tab . 6.For cases with str ong fluid-str ucture interaction, solution stabiliza tion ma y help c onvergenc e for boundar y zones . Solution stabiliza tion c an b e set in the Solver Options tab . See Solution S tabiliza tion for D ynamic M esh B oundar y Zones (p.1364 ) for details . 7.Click Create. 11.6.9.8. Solution Stabilization for D ynamic Mesh B oundar y Zones For c ases with str ong fluid-str ucture in teraction, stabiliza tion is achie ved thr ough a b oundar y sour ce coefficien t introduced in the c ontinuit y equa tion, designed t o impr ove the diagonal dominanc e of the ma trix sy stem in the c ells adjac ent to dynamic mesh b oundar y zones .Two metho ds for this boundar y sour ce coefficien t are available: •volume-based This metho d uses the c ell v olume to re-sc ale the diagonal en try of the linear ma trix sy stem corresponding t o the discr etized c ontinuit y equa tion ( ) as : (11.32) •coefficien t-based This metho d dir ectly r e-sc ales the diagonal en try of the linear ma trix sy stem c orresponding to the discr etized c ontinuit y equa tion ( ) as : (11.33) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1364Modeling F lows Using S liding and D ynamic M esheswher e is the sc ale fac tor and is the numb er of c ells. Note tha t the v alue y ou cho ose f or will only aff ect the r ate of c onvergenc e, and will not aff ect the c onverged solution. Note While solution stabiliza tion is a vailable f or all t ypes of d ynamic mesh b oundar y zones , it is mor e commonly needed f or rigid b ody motion with the six degr ees of fr eedom (six DOF) solv er or f or sy stem c oupling motion. It is not r ecommended f or b oundar y zones of t ype interior, as it c an ad versely aff ect convergenc e. Solution stabiliza tion c an b e enabled f or a b oundar y zone b y op ening the Solver Options tab in the Dynamic M esh Z ones D ialog Box (p.3587 ), enabling the Solution S tabiliza tion option, and then defining the settings under Stabiliza tion P aramet ers. Available settings include the Scale F actor ( ) and the Metho d, which c an b e either volume-based or coefficien t-based (default). The Scale F actor must be set t o a nonz ero value f or the stabiliza tion t o ha ve an eff ect. The solv er option settings c an also b e defined using the define/dynamic-mesh/zones/create text command , and a summar y of these settings c an b e pr inted in the c onsole f or each d ynamic z one by using the define/dynamic-mesh/zones/list text command . 11.6.9.9. Solid-B ody K inematics ANSY S Fluen t uses solid-b ody kinema tics if the motion is pr escr ibed based on the p osition and or ient- ation of the c enter of gr avity of a mo ving objec t.This is applic able t o both c ell and fac e zones . The motion of the solid-b ody can b e sp ecified either as a pr ofile or as a user-defined func tion (UDF). A pr ofile ma y be defined b y the f ollowing pr ofile fields: •time (time) •crank angle (angle) (in-c ylinder flo ws only) •position ( , , ) •linear v elocity ( , , ) •angular v elocity ( , , ) •orientation ( , , ) For in-c ylinder simula tions , the v elocity pr ofiles f or v alves c an b e expressed as a func tion of cr ank angle inst ead of time . In addition, transien t boundar y condition pr ofiles c an also b e expressed as a func tion of cr ank angle inst ead of time . For mor e inf ormation ab out tr ansien t profiles , see Defining Transien t Cell Z one and B oundar y Conditions (p.1066 ). Below ar e two examples of a pr ofile f ormat: ((movement_linear 3 point) (time 0 1 2 ) (x 2 3 4 ) (v_y 0 -5 0 ) ) 1365Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshes ((movement_angular 3 point) (time 0 1 2 ) (omega_x 2 3 4 ) ) For in-c ylinder flo ws, crank angles c an b e included in tr ansien t tables as w ell as tr ansien t profiles , in a similar fashion t o time . An example of a tr ansien t table using (cr ank) angle is as f ollows: example 2 3 1 angle temperature 0 300 180 500 360 300 An example of a tr ansien t profile using (cr ank) angle is as f ollows: ((example transient 3 1) (angle 0.000000e+00 1.800000e+02 3.600000e+02) (temperature 3.000000e+02 5.000000e+02 3.000000e+02) ) In addition t o the motion descr iption, you must also sp ecify the star ting lo cation of the c enter of gravity and or ientation of the solid b ody. In 2D c ases (and 3D c ases tha t do not use the six DOF solv er), ANSY S Fluen t aut oma tically up dates the c enter of gr avity position and or ientation a t every time st ep such tha t (11.34) wher e and are the p osition and or ientation of the c enter of gr avity, and are the linear and angular v elocities of the c enter of gr avity. 3D, six DOF c ases use a mor e comple x form of Equa- tion 11.34 (p.1366 ) when up dating . Typic ally, is chosen t o be an appr opriate set of E uler angles . In this c ase, the solid-b ody motion must b e sp ecified using a user-defined func tion (DEFINE_CG_MOTION ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1366Modeling F lows Using S liding and D ynamic M eshesFigur e 11.93: Solid B ody Rota tion C oordina tes The p osition v ectors on the solid b ody are up dated based on r otation ab out the instan taneous angular velocity vector . For a finit e rotation angle = , the final p osition of a v ector on the solid b ody with r espect to can b e expressed as (S ee Figur e 11.93: Solid B ody Rotation C oordin- ates (p.1367 )) (11.35) wher e can b e sho wn t o be (11.36) The unit v ectors and are defined as (11.37) (11.38) If the solid b ody is also tr ansla ting with , the position v ector on the solid b ody can b e expressed as (11.39) wher e is giv en b y Equa tion 11.35 (p.1367 ). 1367Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshes11.6.10. Previewing the D ynamic M esh When y ou ha ve sp ecified the mesh up date metho ds and their asso ciated par amet ers, and y ou ha ve defined the motion of d ynamic z ones , as descr ibed in Specifying the M otion of D ynamic Z ones (p.1345 ), you c an pr eview the motion of the mesh or the z one as it changes with time b efore you star t your simula tion. The same d ynamic z one or mesh motion will b e execut ed when y ou star t your simula tion. 11.6.10.1. Previewing Z one Motion You c an pr eview the motion of z ones with Rigid B ody or User-D efined motion using the Zone M otion Dialog Box (p.3598 ) (Figur e 11.94: The Z one M otion D ialog Box (p.1368 )). Setup → Dynamic M esh → Displa y Zone M otion... Figur e 11.94: The Z one M otion D ialo g Box The z one motion pr eview only up dates the gr aphic al represen tation (in the gr aphics windo w) of the zones tha t you ha ve selec ted in the Dynamic F ace Zones list. Only z ones tha t ha ve been sp ecified with either User-D efined or Rigid B ody motion t ype ar e available f or z one motion pr eview .To use the Zone M otion preview : 1.In the Zone M otion D ialog Box (p.3598 ), selec t the fac e zones f or which y ou w ant to pr eview the motion from the Dynamic F ace Zones list. The Dynamic F ace Zones list displa ys zones tha t ha ve either User- Defined or Rigid B ody motion sp ecified . By default , all such z ones ar e selec ted. 2.Enter the Start Time ,Time S tep, and Numb er of S teps under Time C ontrol. 3.Click the Preview butt on t o pr eview the z one motion. This p ositions the mesh acc ording t o the sp ecified Start Time , and then in tegrates the p osition of the selec ted sur faces in time .The z one p ositions a t the specified Start Time can b e pr eview ed without an y subsequen t motion b y en tering 0 f or the Numb er of S teps. 4.Click Reset to restore the mesh t o its initial sta te. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1368Modeling F lows Using S liding and D ynamic M eshesPreviewing the z one motion c an also b e used as a p ostpr ocessor f or six DOF simula tions (see Six DOF Solver S ettings (p.1328 )). 11.6.10.2. Previewing Mesh Motion The mesh motion pr eview is diff erent from the z one motion descr ibed ab ove in tha t the mesh c on- nectivit y is changed in mesh motion. To pr eview the d ynamic mesh of a tr ansien t case, you c an use the Mesh M otion D ialog Box (p.3599 ) (Figur e 11.95: The M esh M otion D ialog Box (p.1369 )) Setup → Dynamic M esh → Preview M esh M otion... Figur e 11.95: The M esh M otion D ialo g Box The pr ocedur e is as f ollows: 1.Save the c ase file . File → Write → Case... Imp ortant Note tha t the mesh motion will ac tually up date the no de lo cations as w ell as the c on- nectivit y of the mesh, so y ou must b e sur e to sa ve your c ase file b efore doing the d y- namic mesh motion. Onc e you ha ve ad vanced the mesh b y a c ertain numb er of time steps, you will not b e able t o recover the pr evious sta tus of the mesh, other than b y reloading the appr opriate ANSY S Fluen t case file . 2.Specify the Numb er of Time S teps and the siz e of each time st ep ( Time S tep S ize).The cur rent time will b e displa yed in the Current Mesh Time field af ter the d ynamic mesh has b een ad vanced the sp ecified numb er of st eps. 1369Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshesNote tha t if y ou tur ned on the in-c ylinder option, the Time S tep S ize is aut oma tically c alcula ted from the Crank A ngle S tep S ize and the Crank S haft Speed tha t you ha ve sp ecified in the In- Cylinder tab of the Options D ialog Box (p.3575 ). 3.To view the d ynamic mesh in the gr aphics windo w, enable the Displa y M esh option. In addition, you can c ontrol the fr equenc y at which ANSY S Fluen t should displa y an up dated mesh in the Displa y Fre- quenc y field .To sa ve a pic ture file of the mesh each time ANSY S Fluen t up dates it dur ing the pr eview , turn on the Save Picture option. This op ens the Save Picture Dialog Box (p.3676 ) (see Saving P icture Files (p.645)). 4.Turn on Enable A utosa ve to use the aut oma tic sa ving f eature to sp ecify the file name and fr equenc y with which c ase and da ta files should b e sa ved dur ing the solution pr ocess.This op ens the Autosave Case D uring M esh M otion P review D ialog Box (p.3600 ). See Automa tic S aving of C ase and D ata Files (p.591) for details ab out the use of this f eature.This provides a c onvenien t way for y ou t o sa ve results a t succ essiv e time st eps f or la ter p ostpr ocessing . 5.Enable the Update M esh In terfaces option t o up date the in terface at every time st ep. 6.Enable the Update Overset In terfaces option t o up date the o verset in terface at every time st ep. 7.Use the Update M onit ors option t o disable the pr ocessing of monit ors and c omputa tion ac tivities dur ing mesh motion pr eview .This allo ws you t o set up monit ors and c omputa tional ac tivities b efore running mesh motion pr eview without cr eating monit or files dur ing the mesh motion pr eview . 8.Click Preview to star t the pr eview . ANSY S Fluen t will up date the d ynamic mesh b y mo ving and def orming the fac e and c ell z ones tha t you ha ve sp ecified as d ynamic z ones . Click Apply to sa ve your settings f or mesh motion. During the pr eview , information ab out the d ynamic mesh will b e displa yed in the c onsole windo w for each time st ep. Note tha t for the in-c ylinder option, the r eported Maximum Cell Skew is c al- cula ted only fr om z ones under going r emeshing .This ensur es tha t you c an alw ays asc ertain whether the sk ewness is incr easing in the def orming z ones .To report the maximum sk ewness of a c ell fr om any zone , you c an click the Rep ort Qualit y butt on in the Gener al Task P age (p.3235 ). Setup → Gener al → Rep ort Qualit y 11.6.11. Stead y-State Dynamic M esh A pplic ations While man y dynamic mesh pr oblems ar e transien t, you c an use d ynamic meshes f or st eady-sta te ap- plications as w ell. Some e xamples of st eady-sta te applic ations include: check ing the v alve applic ation after reaching a st eady-sta te valve position; or af ter a fluid-str ucture in terface applic ation has r eached a steady-sta te solution. There ar e no diff erences in the meshing asp ect between st eady-sta te cases and tr ansien t cases . Fur- ther mor e, setting up a st eady-sta te simula tion is similar t o setting up a tr ansien t case, descr ibed in Using D ynamic M eshes (p.1264 ). However, ther e ar e a f ew diff erences tha t you should not e: •A CG_MOTION UDF is needed t o sp ecify the motion of the b oundar y: a tr ansien t profile used in tr ansien t cases c annot b e used in st eady-sta te cases . •The dtime passed t o the CG_MOTION UDF is 1 b y default: if a displac emen t of 1 mm is needed t o mo ve the b oundar y, you c an sp ecify the v elocity to be 1e-3 m/s . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1370Modeling F lows Using S liding and D ynamic M eshes•Dynamic mesh par amet ers c an b e diff erent sinc e an in terpolation er ror is no longer a c oncern. •If you ha ve enabled lo cal remeshing f or y our st eady-sta te applic ation, you c an instr uct ANSY S Fluen t to perform additional r emeshing af ter the b oundar y has mo ved.This additional r emeshing is based on skewness cr iteria, and c an fur ther incr ease the qualit y of y our mesh. See Dynamic M esh U pdate Meth- ods (p.1267 ) for fur ther details . The mesh must b e manually up dated thr ough jour nal files or e xecut e commands .To up date the mesh, you c an use the Mesh M otion D ialog Box (p.3599 ). Solution → Run C alcula tion → Update D ynamic M esh... Alternatively, you c an use the f ollowing t ext command: solve → mesh-motion which c an also b e used as an e xecut e command in the Execut e Commands D ialog Box (p.3637 ): Note When y ou ar e solving a pr oblem using the six DOF solv er, you ma y need t o mo dify the pseudo time st ep siz e in or der f or the solv er to converge. It is also r ecommended tha t you ensur e tha t the st eady-sta te solution is r easonably w ell c onverged b efore performing the steady-sta te dynamic mesh up date. Solution → Calcula tion A ctivities → Execut e Commands New... You c an displa y dynamic mesh sta tistics (such as minimum and maximum v olumes and maximum c ell and fac e sk ewness) b y click ing the Update butt on in the Mesh M otion D ialog Box (p.3599 ) (Fig- ure 11.96: The M esh M otion D ialog Box for S teady-State Dynamic M eshes (p.1371 )). Figur e 11.96: The M esh M otion D ialo g Box for S tead y-State D ynamic M eshes Imp ortant The f ollowing options ar e not a vailable f or st eady-sta te applic ations: •In-C ylinder •Implicit U pdate Also, the Dynamic M esh E vents dialo g box is not a vailable f or st eady-sta te applic ations . 1371Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshes11.6.11.1. An Example of St eady -Stat e Dynamic Mesh Usage Consider a r escue dr op c ase sho wn in Figur e 11.97: Initial O bjec t Position (p.1372 ).The objec t can b e moved in an y position in the st eady-sta te solv er, after which st eady-sta te analy ses c an b e performed at diff erent objec t positions . Figur e 11.97: Initial O bjec t Position The d ynamic mesh par amet ers setup is iden tical for the st eady-sta te and tr ansien t cases , which is descr ibed in Setting D ynamic M esh M odeling P aramet ers (p.1266 ).When setting up the d ynamic z ones , the pr ocedur es ar e similar t o those descr ibed in Specifying the M otion of D ynamic Z ones (p.1345 ), except tha t the UDF selec ted fr om the Motion UDF/P rofile drop-do wn list is diff erent. In st eady-sta te cases the dtime passed t o the UDF is b y default 1. So, in this e xample , the objec t will mo ve 50 mm each time the f ollowing UDF is e xecut ed: #include "udf.h" DEFINE_CG_MOTION(pod,dt,vel,omega,time,dtime) { NV_S(vel,=,0); NV_S(omega,=,0); vel[1] = -50e-3; } The r esulting mesh is sho wn in Figur e 11.99: Final O bjec t Position A fter 40 Ex ecutions (p.1373 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1372Modeling F lows Using S liding and D ynamic M eshesFigur e 11.98: The M esh M otion D ialo g Box After 40 U pdates Figur e 11.99: Final O bjec t Position A fter 40 E xecutions 1373Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M eshesRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1374Chapt er 12: Modeling Turbulenc e This chapt er pr ovides details ab out ho w to use the turbulenc e mo dels a vailable in ANSY S Fluen t. Information ab out turbulenc e mo deling theor y is pr esen ted in Turbulenc e in the Theor y Guide . Inform- ation ab out using the turbulenc e mo dels c an b e found in the f ollowing sec tions: 12.1. Introduction 12.2. Choosing a Turbulenc e Model 12.3. Steps in U sing a Turbulenc e Model 12.4. Setting U p the S palar t-Allmar as M odel 12.5. Setting U p the k- ε Model 12.6. Setting U p the k- ω Model 12.7. Setting U p the Transition k-k l-ω Model 12.8. Setting U p the Transition SST M odel 12.9. Setting U p the In termitt ency Transition M odel 12.10. Setting U p the R eynolds S tress M odel 12.11. Setting U p Sc ale-A daptiv e Simula tion (SAS) M odeling 12.12. Setting U p the D etached E ddy Simula tion M odel 12.13. Setting U p the Lar ge E ddy Simula tion M odel 12.14. Model C onstan ts 12.15. Setting U p the Emb edded Lar ge E ddy Simula tion (ELES) M odel 12.16. Setup Options f or A ll Turbulenc e Modeling 12.17. Defining Turbulenc e Boundar y Conditions 12.18. Providing an Initial G uess f or k and ε (or k and ω) 12.19. Solution S trategies f or Turbulen t Flow Simula tions 12.20. Postpr ocessing f or Turbulen t Flows 12.1. Introduc tion Turbulenc e is the thr ee-dimensional unst eady random motion obser ved in fluids a t mo derate to high Reynolds numb ers. As technic al flo ws are typic ally based on fluids of lo w visc osity, almost all t echnic al flows are turbulen t. Many quan tities of t echnic al in terest dep end on turbulenc e, including: •Mixing of momen tum, ener gy and sp ecies •Heat transf er •Pressur e losses and efficienc y •Forces on aer odynamic b odies While turbulenc e is, in pr inciple , descr ibed b y the N avier-S tokes equa tions , it is not f easible in most situa tions t o resolv e the wide r ange of sc ales in time and spac e by Direct Numer ical Simula tion (DNS) as the CPU r equir emen ts w ould b y far e xceed the a vailable c omputing p ower for an y foreseeable futur e. For this r eason, averaging pr ocedur es ha ve to be applied t o the N avier-S tokes equa tions t o filt er out all, or a t least , par ts of the turbulen t sp ectrum. The most widely applied a veraging pr ocedur e is R eynolds- averaging (which, for all pr actical pur poses is time-a veraging) of the equa tions , resulting in the R eynolds- 1375Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Averaged N avier-S tokes (R ANS) equa tions . By this pr ocess, all turbulen t str uctures ar e elimina ted fr om the flo w and a smo oth v ariation of the a veraged v elocity and pr essur e fields c an b e obtained . However, the a veraging pr ocess in troduces additional unk nown t erms in to the tr ansp ort equa tions (R eynolds Stresses and F luxes) tha t need t o be pr ovided b y suitable turbulenc e mo dels (turbulenc e closur es).The qualit y of the simula tion c an dep end cr ucially on the selec ted turbulenc e mo del and it is imp ortant to mak e the pr oper mo del choic e as w ell as t o pr ovide a suitable numer ical gr id for the selec ted mo del. An alt ernative to RANS ar e Sc ale-R esolving S imula tion (SRS) mo dels .With SRS metho ds, at least a p ortion of the turbulen t sp ectrum is r esolv ed in a t least a par t of the flo w domain. The most w ell-k nown such metho d is Lar ge E ddy Simula tion (LES), but man y new h ybrids (mo dels b etween R ANS and LES) ar e app earing. As all SRS metho ds r equir e time-r esolv ed simula tions with r elatively small time st eps, it is imp ortant to understand tha t these metho ds ar e substan tially mor e computa tionally e xpensiv e than RANS simula tions . ANSY S Fluen t provides the f ollowing choic es of turbulenc e mo dels: •Spalar t-Allmar as mo del • - mo dels –Standar d - mo del –Renor maliza tion-gr oup (RNG) - mo del –Realizable - mo del • - mo dels –Standar d - mo del –Baseline (BSL) - mo del –Shear-str ess tr ansp ort (SST ) - mo del • mo del (add-on) •Transition - - mo del •Transition SST mo del •Reynolds str ess mo dels (RSM) –Linear pr essur e-str ain RSM –Quadr atic pr essur e-str ain RSM –Stress-Omega RSM –Stress-BSL RSM •Scale-A daptiv e Simula tion (SAS) mo del, which c an b e used in c ombina tion with one of the f ollowing -based URANS mo dels: –SST - mo del –Standar d - mo del Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1376Modeling Turbulenc e–BSL - mo del –Transition SST mo del – -based R eynolds str ess mo dels (RSM) •Detached edd y simula tion (DES) mo del, which includes one of the f ollowing R ANS mo dels . –Spalar t-Allmar as R ANS mo del –Realizable - RANS mo del –SST - RANS mo del –BSL - RANS mo del –Transition SST mo del •Shielded D etached E ddy Simula tion (SDES) mo del, which includes one of the f ollowing R ANS mo dels . –SST - RANS mo del –BSL - RANS mo del –Transition SST mo del •Stress-B lended E ddy Simula tion (SBES) mo del, which includes one of the f ollowing R ANS mo dels . –SST - RANS mo del –BSL - RANS mo del –Transition SST mo del •Large edd y simula tion (LES) mo del, which includes one of the f ollowing sub grid-sc ale mo dels . –Smagor insk y-Lilly sub grid-sc ale mo del (with or without d ynamic str ess enabled) –WALE sub grid-sc ale mo del –Dynamic k inetic ener gy sub grid-sc ale mo del –Wall-M odeled LES ( WMLES) –Wall-M odeled LES - (WMLES - ) 12.2. Choosing a Turbulenc e M odel It is an unf ortuna te fac t tha t no single turbulenc e mo del is univ ersally acc epted as b eing sup erior f or all classes of pr oblems .The choic e of turbulenc e mo del will dep end on c onsider ations such as the physics of the flo w, the established pr actice for a sp ecific class of pr oblem, the le vel of accur acy requir ed, the a vailable c omputa tional r esour ces, and the amoun t of time a vailable f or the simula tion. To mak e the most appr opriate choic e of mo del f or y our applic ation, you need t o understand the c apabilities and limita tions of the v arious options . 1377Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Choosing a Turbulenc e ModelThe pur pose of this sec tion is t o giv e an o verview of issues r elated t o the turbulenc e mo dels pr ovided in ANSY S Fluen t.The c omputa tional eff ort and c ost in t erms of CPU time and memor y of the individual models is discussed .While it is imp ossible t o sta te categor ically which mo del is b est f or a sp ecific ap- plication, gener al guidelines ar e pr esen ted t o help y ou cho ose the appr opriate turbulenc e mo del f or the flo w you w ant to mo del. Note For inf ormation on turbulenc e mo del c ompa tibilit y with other F luen t mo dels , see Ap- pendix A: ANSY S Fluen t Model C ompa tibilit y (p.3965 ). For additional inf ormation, see the f ollowing sec tions: 12.2.1. Reynolds A veraged N avier-S tokes (R ANS) Turbulenc e Models 12.2.2. Scale-R esolving S imula tion (SRS) M odels 12.2.3. Grid Resolution SRS M odels 12.2.4. Numer ics S ettings f or SRS M odels 12.2.5. Model Hier archy 12.2.1. Reynolds A veraged N avier-S tokes (R ANS) Turbulenc e M odels RANS mo dels ( Reynolds (Ensemble) A veraging in the Theor y Guide ) off er the most ec onomic appr oach for c omputing c omple x turbulen t industr ial flo ws.Typic al examples of such mo dels ar e the - or the - mo dels in their diff erent forms.These mo dels simplify the pr oblem t o the solution of t wo addi- tional tr ansp ort equa tions and in troduce an E ddy-Viscosity (turbulen t visc osity) to comput e the R eynolds Stresses . More comple x RANS mo dels ar e available tha t solv e an individual equa tion f or each of the six indep enden t Reynolds S tresses dir ectly (R eynolds S tress M odels – RSM) plus a sc ale equa tion ( -equa tion or -equa tion). RANS mo dels ar e suitable f or man y engineer ing applic ations and t ypic ally provide the le vel of accur acy requir ed. Since none of the mo dels is univ ersal, you ha ve to decide which model is the most suitable f or a giv en applic ations . 12.2.1.1. Spalar t-Allmar as O ne-E quation Mo del The S palar t-Allmar as mo del is a r elatively simple one-equa tion mo del tha t solv es a mo deled tr ansp ort equa tion f or the k inema tic edd y (turbulen t) visc osity.The S palar t-Allmar as mo del w as designed sp e- cific ally f or aer onautics and aer ospac e applic ations in volving w all-b ounded flo ws and has b een sho wn to giv e go od results f or b oundar y layers subjec ted t o ad verse pr essur e gr adien ts. It is also gaining popular ity in turb omachiner y applic ations . Do not use the mo del as a gener al pur pose mo del, as it is not w ell c alibr ated f or fr ee shear flo ws (lar ge er rors f or e xample , jet flo ws). The S palar t-Allmar as mo del has b een e xtended within ANSY S Fluen t with a -insensitiv e wall tr eat- men t, which aut oma tically blends all solution v ariables fr om their visc ous subla yer formula tion t o the corresponding lo garithmic la yer v alues dep ending on .The blending is c alibr ated t o also c over in- termedia te values in the buff er la yer 12.2.1.2. k-ε Mo dels Two-equa tion mo dels ar e hist orically the most widely used turbulenc e mo dels in industr ial CFD .They solv e two transp ort equa tions and mo del the R eynolds S tresses using the E ddy Viscosity appr oach. The standar d - mo del in ANSY S Fluen t falls within this class of mo dels and has b ecome the w orkhorse of pr actical engineer ing flo w calcula tions in the time sinc e it w as pr oposed b y Launder and S palding Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1378Modeling Turbulenc e[63] (p.4008 ). Robustness , econom y, and r easonable accur acy for a wide r ange of turbulen t flo ws explain its p opular ity in industr ial flo w and hea t transf er simula tions . The dr aw-back of some - mo dels is their insensitivit y to ad verse pr essur e gr adien ts and b oundar y layer separ ation. They typic ally pr edic t a dela yed and r educ ed separ ation r elative to obser vations . This c an r esult in o verly optimistic design e valua tions f or flo ws tha t separ ate from smo oth sur faces (for e xample , aer odynamic b odies , diffusers). The - mo del is ther efore not widely used in e xternal aerodynamics . In ANSY S Fluen t, the use of the R ealizable - mo del is r ecommended r elative to other v ariants of the - family .You should use the - mo del in c ombina tion with either the Enhanc ed Wall Treatmen t (EWT- ) or the M enter-L echner near-w all tr eatmen t. For details , refer to Enhanc ed Wall Treatmen t ε- Equa tion (E WT-ε) or Menter-L echner ε-Equa tion (ML- ε) in the Theor y Guide , respectively. For c ases wher e the flo w separ ates under ad verse pr essur e gr adien ts fr om smo oth sur faces (air foils, and so on), - mo dels ar e gener ally not r ecommended . 12.2.1.3. k-ω Mo dels The -equa tion off ers se veral ad vantages r elative to the -equa tion. The most pr ominen t one is tha t the equa tion c an b e in tegrated without additional t erms thr ough the visc ous subla yer.This mak es the f ormula tion of a r obust -insensitiv e treatmen t relatively str aigh tforward. Refer to y+-Insensitiv e Wall Treatmen t ω-Equa tion in the Theor y Guide for details . Further mor e, - mo dels ar e typic ally better a t predic ting ad verse pr essur e gr adien t boundar y layer flo ws and separ ation. The do wnside of the standar d -equa tion is a r elatively str ong sensitivit y of the solution dep ending on the fr eestr eam values of and outside the shear la yer.The use of the standar d - mo del is , for this r eason, not gener ally r ecommended in ANSY S Fluen t. The BSL and SST - mo dels ha ve been designed t o avoid the fr eestr eam sensitivit y of the standar d - mo del, by combining elemen ts of the -equa tion and the -equa tion. In addition, the SST model has b een c alibr ated t o accur ately c omput e flo w separ ation fr om smo oth sur faces.Within the - mo del family , it is ther efore recommended t o use either the BSL or SST mo del. These mo dels are some of the most widely used mo dels f or aer odynamic flo ws.They are typic ally somewha t mor e accur ate in pr edic ting the details of the w all b oundar y layer char acteristics than the S palar t-Allmar as model. The BSL and SST mo dels (lik e all other -equa tion based mo dels) use the -insensitiv e wall treatmen t by default. For the - mo dels , so-c alled lo w Reynolds numb er terms (lo w Re) ha ve been pr oposed b y Wilcox. These ar e available in ANSY S Fluen t as an option. It is imp ortant to point out tha t these t erms ar e not r equir ed f or in tegrating the equa tions thr ough the visc ous subla yer.Their main influenc e lies in mimick ing laminar-turbulen t transition pr ocesses . However, this func tionalit y is not widely c alibr ated and f or w all-b oundar y layer tr ansition, the c ombina tion of the SST mo del with the Transition SST model ( Transition SST M odel in the Theor y Guide ), Intermitt ency Transition mo del ( Intermitt ency Transition M odel in the Theor y Guide ), or the Transition - - mo del ( k-kl-ω Transition M odel in the Theor y Guide ) is mor e reliable .The use of the lo w-R e terms is ther efore not enc ouraged . 12.2.1.4. Gener aliz ed k-ω (GEK O) Mo del The goal of the GEK O mo del is t o off er a single mo del with enough fle xibilit y to cover a wide r ange of applic ations . Although most applic ations ar e alr eady covered b y the default settings , the mo del provides f our fr ee par amet ers tha t can b e adjust ed f or sp ecific t ypes of applic ations , without nega tive impac t on the basic c alibr ation of the mo del. This is a p owerful t ool for mo del optimiza tion, but r equir es a pr oper understanding of the impac t of these c oefficien ts to avoid mistuning . It is imp ortant to 1379Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Choosing a Turbulenc e Modelemphasiz e tha t the mo del has str ong defaults , so y ou c an also apply the mo del without an y fine- tuning and tha t you should mak e sur e tha t an y tuning is supp orted b y high-qualit y experimen tal data. In most c ases , you need t o only adjust to change the GEK O mo del’s sensitivit y to boundar y layer separ ation. The figur e below sho ws the impac t of this par amet er for a diffuser flo w [148] (p.4013 ). With , the mo del b ehaves essen tially the same as the mo del (no separ ation) and with , close t o perfect agr eemen t with the da ta is achie ved (lik e the SST mo del [149] (p.4013 )). Larger v alues f or can b e requir ed (f or e xample , when simula ting high-lif t air foils, wher e even the SST mo del t ends t o under-estima te separ ation str ength). Figur e 12.1: Velocity Profiles f or A xi-symmetr ic D iffuser F low (C ase CS0 – D river). Impac t of Variation of The figur e below sho ws variations of for a fr ee mixing la yer ( ) [150] (p.4013 ). Incr easing leads t o incr eased turbulenc e levels and lar ger spr eading r ates. Figur e 12.2: Impac t of C hanges in on F ree M ixing L ayer. Left:Velocity Profiles , Right: Turbulenc e Kinetic E nergy Profiles The impac t of is sho wn in the figur e below for the r eattachmen t region of a back ward-facing step [151] (p.4013 ). Both the w all shear str ess c oefficien t and the S tanton numb er for hea t transf er, , are str ongly aff ected. Incr easing leads t o higher and numb ers in this non-equilibr ium region. In most c ases , ther e is no need t o change from its default v alue . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1380Modeling Turbulenc eFigur e 12.3: Impac t of C hanges in on B ack ward Facing J et with H eat Transf er. Left:Wall Shear S tress C oefficien t, , Right:Wall H eat Transf er C oefficien t, The figur e below sho ws the influenc e of for plane [152] (p.4013 ) and r ound jet flo ws [153] (p.4013 )( =2, =0.35, =0.5). Incr easing (while is ac tive) reduc es the spreading r ate for jet flo ws without changing the spr eading r ate of mixing la yers. is a sub- model of and ther efore loses its eff ectiveness in c ases wher e is reduc ed. Figur e 12.4: Impac t of C hanges in on F ree J et F lows. Left: Plane J et, Right: Round J et Note tha t the r egion wher e is ac tive is defined b y the blending func tion . In r egions wher e =1 (near w alls) ther e is no eff ect when changing . can b e visualiz ed in the P ost Processor . It can also b e augmen ted b y the mo dific ation of e xpert par amet ers (see Gener alized k-ω (GEK O) M odel in the Fluent Theor y Guide ) or b y over-wr iting the func tion via a UDF (see DEFINE_K W_GEK O Coefficien ts and B lending F unction in the Fluent C ustomization Manual ). 12.2.1.5. Reynold Str ess Mo dels Reynolds S tress mo dels (RSM) include se veral eff ects tha t are not easily handled b y Eddy-Viscosity models .The most imp ortant eff ect is the stabiliza tion of turbulenc e due t o str ong r otation and streamline cur vature (as obser ved f or e xample , in c yclone flo ws). RSM on the other hand of ten demand a signific ant incr ease in c omputing time par tly due t o the additional equa tions but mostly due t o reduc ed c onvergenc e.This additional eff ort is not alw ays justified b y incr eased accur acy.Their usage is ther efore not gener ally r ecommended and should b e restricted t o flo ws for which their sup eriority 1381Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Choosing a Turbulenc e Modelhas b een established , esp ecially flo w with str ong swir l and r otation. If wall b oundar y layers ar e im- portant, the c ombina tion of RSM with the - or BSL-equa tion is mor e accur ate than the c ombina tion with the -equa tion. The c ombina tion of RSM with BSL r emo ves the fr ee-str eam sensitivit y obser ved with the -equa tion in the same w ay as f or two-equa tion mo dels . 12.2.1.6. Laminar -Turbulent Transition Mo dels The f ollowing thr ee mo dels f or tr ansition pr edic tion ar e available in ANSY S Fluen t.Two of them c an be combined with the sc ale-r esolving metho ds descr ibed in Scale-R esolving S imula tion (SRS) M od- els (p.1385 ). •the Transition SST mo del (also k nown as the - mo del) This mo del c an b e combined with Sc ale-A daptiv e Simula tion, Detached E ddy Simula tion, Stress- Blended E ddy Simula tion, and S hielded D etached E ddy Simula tion. •the In termitt ency Transition mo del (also k nown as the mo del, and a vailable f or BSL, SST , Scale-A daptiv e Simula tion with BSL / SST , Detached E ddy Simula tion with BSL / SST , Stress-B lended E ddy Simula tion with BSL / SST , and S hielded D etached E ddy Simula tion with BSL / SST ) •the Transition - - mo del For man y test c ases , the thr ee mo dels pr oduce similar r esults . Due t o their c ombina tion with the SST model, the Transition SST mo del and the In termitt ency Transition mo del ar e recommended o ver the Transition - - mo del. The Transition SST mo del is not G alilean in variant, and should ther efore not be applied t o sur faces tha t mo ve relative to the c oordina te sy stem f or which the v elocity field is comput ed; further mor e, it is not suitable f or fully de velop ed pip e / channel flo ws wher e no fr eestr eam is pr esen t. For such c ases , the In termitt ency Transition mo del should b e used inst ead (though y ou may need t o adjust the In termitt ency Transition mo del f or pip e / channel flo ws by mo difying the under lying c orrelations). Among the thr ee mo dels , only the In termitt ency Transition mo del is c apable of acc oun ting f or cr ossflo w instabilit y. When using these mo dels , not e the f ollowing: •These mo dels ar e only applic able t o wall-b ounded flo ws. Like all other engineer ing tr ansition mo dels , they are not applic able t o transition in fr ee shear flo ws.They will pr edic t free shear flo ws as fully turbulen t. •These mo dels ha ve not b een c alibr ated in c ombina tion with other ph ysical eff ects tha t aff ect the sour ce terms of the turbulenc e mo del, such as: –buo yancy –multiphase turbulenc e •No sp ecial c alibr ation has b een p erformed f or the c ombina tion of the Transition SST and In termitt ency Transition mo del with sc ale-r esolving metho ds. Note tha t the ac tivation of the LES t erm in the fr eestr eam in an y hybrid R ANS-LES mo del c an aff ect the dec ay of the fr eestr eam turbulenc e, which in tur n aff ects the tr ansition lo cation. •Proper mesh r efinemen t and sp ecific ation of inlet turbulenc e levels is cr ucial f or accur ate transition pr e- diction. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1382Modeling Turbulenc e•In gener al, ther e is some additional eff ort requir ed dur ing the mesh gener ation phase b ecause a lo w-R e mesh with sufficien t str eamwise r esolution is needed t o accur ately r esolv e the tr ansition r egion. Further- mor e, in r egions wher e laminar separ ation o ccurs , additional mesh r efinemen t is nec essar y in or der t o properly captur e the r apid tr ansition due t o the separ ation bubble . •The dec ay of turbulenc e from the inlet t o the leading edge of the de vice should alw ays be estima ted b efore running a solution as this c an ha ve a lar ge eff ect on the pr edic ted tr ansition lo cation. Physically c orrect values f or the turbulenc e intensit y (Tu) should b e achie ved near the lo cation of tr ansition. 12.2.1.7. Curvatur e Correction for the Spalar t-Allmar as and Two-E quation Mo dels One w eakness of the edd y-visc osity mo dels is tha t these mo dels ar e insensitiv e to str eamline cur vature and sy stem r otations , which pla y an imp ortant role in man y turbulen t flo w applic ations .To sensitiz e the standar d edd y-visc osity mo dels t o these cur vature eff ects, you c an use a mo dified turbulenc e produc tion t erm. For mor e inf ormation, see Curvature Correction f or the S palar t-Allmar as and Two- Equa tion M odels in the Fluent Theor y Guide . 12.2.1.8. Produc tion Limit ers for Two-E quation Mo dels A disad vantage of standar d two-equa tion turbulenc e mo dels is the e xcessiv e gener ation of the tur- bulenc e ener gy, , in the vicinit y of stagna tion p oints. In or der t o avoid the buildup of turbulen t kinetic ener gy in the stagna tion r egions , the pr oduc tion t erm in the turbulenc e equa tions c an b e limit ed b y one of the t wo formula tions descr ibed in Produc tion Limit ers f or Two-Equa tion M odels in the Fluent Theor y Guide . 12.2.1.9. Mo del E nhanc ements There ar e man y mo del enhanc emen ts available f or turbulenc e mo dels .While such enhanc emen ts can impr ove simula tions in some c ases , the y can also ha ve detr imen tal eff ects.The gener al recommend- ation is ther efore to use them with c aution. As not ed ab ove, the use of lo w-R e terms in c ombina tion with the -equa tion is not gener ally r ecom- mended . Another mo del enhanc emen t tha t should b e used with c are is the c ompr essibilit y eff ects of S arkar ([108] (p.4011 )). It can impr ove the pr edic tion of fr ee shear la yers a t high M ach numb ers, but has also shown a pr onounc ed nega tive impac t on w all b oundar y layers. It is ther efore not gener ally r ecom- mended .The c ompr essibilit y eff ects option is a vailable in the Viscous M odel D ialog Box (p.3253 ) when the c ompr essible f orm of the ideal gas la w or the r eal-gas mo del is enabled .This option is disabled by default (though this w as not the c ase in v ersion 14.5 and ear lier) and it is r ecommended tha t you keep this option disabled f or c ases not in volving fr ee shear flo ws. Buoyancy has a pr onounc ed eff ect on turbulenc e (Effects of B uoyancy on Turbulenc e in the Theor y Guide ).The use of the sour ce term in the -equa tion is ther efore recommended f or buo yancy aff ected flows.The sour ce term in the -equa tion and -equa tion is much less established and the t erm should be enabled with c are. 12.2.1.10. Wall Treatment for R ANS Mo dels It is r ecommended tha t you use a -insensitiv e wall tr eatmen t for all mo dels f or which it is a vailable (Spalar t-Allmar as, -equa tion and -equa tion). It provides the most c onsist ent wall shear str ess and wall hea t transf er pr edic tions with the least sensitivit y to values . (See an Overview of the S palar t- 1383Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Choosing a Turbulenc e ModelAllmar as mo del, Enhanc ed Wall Treatmen t ε-Equa tion (E WT-ε),Menter-L echner ε-Equa tion (ML- ε), and y+-Insensitiv e Wall Treatmen t ω-Equa tion in the Theor y Guide for mor e inf ormation.) When Wall F unctions ar e used , it is nec essar y to avoid gr ids with fine near w all spacing . It is r ecom- mended tha t you use in the en tire domain. The applic ation of Wall F unctions is , however, not gener ally r ecommended as the y do not allo w a sy stema tic r efinemen t of the near w all gr id.Wall Functions ar e esp ecially damaging f or flo ws at low to medium R eynolds numb ers (R e~ - ), as the assumption of an e xtended lo garithmic la yer is not v alid in these c ases . In c ase tha t Wall F unctions are desir ed, the option of Sc alable Wall F unctions ( Scalable Wall F unctions in the Theor y Guide ) avoids the gr id restrictions and c an b e run on fine meshes . 12.2.1.11. Grid R esolution for R ANS Mo dels Grid gener ation has a str ong impac t on mo del accur acy.There ar e man y consider ations tha t ha ve to be followed when gener ating high qualit y CFD gr ids. From a turbulenc e mo deling standp oint, the most imp ortant one is tha t the r elevant shear la yers should b e covered b y at least ~10 c ells nor mal to the la yer. Below this r esolution, the mo del will not b e able t o pr ovide its c alibr ated p erformanc e. Especially f or fr ee shear flo ws, whose lo cation is not k nown dur ing gr id gener ation, this is a r equir emen t that is har d to achie ve. Nevertheless , you should b e aware tha t for lo wer resolution, the mo del p er- formanc e can degr ade. For w all b ounded flo ws, a str uctured mesh in w all-nor mal dir ection is highly r ecommended .The structured p ortion of the mesh should c over the en tire boundar y layer and e xtend b eyond the boundar y layer thick ness t o avoid r estricting the gr owth of the b oundar y layer. Advanced turbulenc e models f or w all b oundar y layers lik e the S palar t-Allmar as mo del and the SST mo del will only pr ovide impr oved r esults t o other mo dels if a minimum of 10 or mor e str uctured (he x or pr ism) c ells ar e lo cated inside the b oundar y layer. In addition, one should ensur e tha t the pr ism la yer covers the w all boundar y layer en tirely. Note tha t these ar e not sp ecific r equir emen ts of these mo dels , but ar e gen- eral requir emen ts for w all b oundar y layer simula tions . Both ε-based and ω-based mo dels off er -insensitiv e wall tr eatmen t options (see Enhanc ed Wall Treatmen t ε-Equa tion (E WT-ε),Menter-L echner ε-Equa tion (ML- ε), and y+-Insensitiv e Wall Treatmen t ω-Equa tion in the Theor y Guide for mor e inf ormation), which mak e the mo dels r elatively insensitiv e to the -value of the w all c ell. Gener ally sp eaking, it is mor e imp ortant to ensur e tha t the b oundar y layer is c overed with sufficien t cells, then t o achie ve a c ertain criterion. However, for simula tions with high accur acy demands on the w all b oundar y layer (esp ecially f or hea t transf er pr edic tions), near-w all meshes with ~1 ar e recommended .When w all func tions ar e used , it is essen tial t o avoid meshes with values lo wer than ~30 as the w all shear str ess and the w all hea t transf er can and will seriously det eriorate under such c onditions . For this r eason, the usage of -insensitiv e wall tr eatmen ts (to be selec ted f or -equa tion and default f or -equa tion based mo dels) is r ecommended . For tr ansition mo dels (see k-kl-ω Transition M odel,Transition SST M odel, and Intermitt ency Transition Model in the Theor y Guide ), mor e str ingen t grid resolution r equir emen ts apply than f or standar d RANS mo dels , as tr ansition mo deling r equir es the r esolution of the thin laminar b oundar y layer up- stream of the tr ansition lo cation. For this r eason, a lo w-R e mesh ( ) with sufficien t str eamwise resolution is needed t o accur ately r esolv e the tr ansition r egion. The e xpansion r atio of the gr id nor mal to the w all should not e xceed 1.1. Further mor e, in r egions wher e laminar separ ation o ccurs , additional mesh r efinemen t is nec essar y, in or der t o pr operly captur e the r apid tr ansition due t o the separ ation bubble . Finally , the dec ay of turbulenc e from the inlet t o the leading edge of the de vice should alw ays be estima ted b efore running a solution as this c an ha ve a lar ge eff ect on the pr edic ted tr ansition location. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1384Modeling Turbulenc e12.2.2. Scale-Resolving S imula tion (SRS) M odels The alt ernative to RANS mo dels ar e mo dels tha t resolv e at least a p ortion of the turbulenc e for a t least a portion of the flo w domain. Such mo dels ar e gener ally t ermed ‘Scale-R esolving ’. 12.2.2.1. Large E ddy S imulation (LES) The most widely k nown SRS mo deling c oncept is Lar ge E ddy Simula tion (LES). It is based on the ap- proach of r esolving lar ge turbulen t str uctures in spac e and time do wn t o the gr id limit e verywher e in the flo w. However, while widely used in the ac ademic c ommunit y, LES had v ery limit ed impac t on industr ial simula tions .The r eason lies in the e xcessiv ely high r esolution r equir emen ts for w all boundar y layers. Near the w all, the lar gest sc ales in the turbulen t sp ectrum ar e ne vertheless geomet- rically v ery small and r equir e a v ery find gr id and a small time st ep. In addition, unlik e RANS, the gr id cannot only b e refined in the w all nor mal dir ection, but also must r esolv e turbulenc e in the w all parallel plane .This c an only b e achie ved f or flo ws at very low Reynolds numb er and on v ery small geometr ic sc ales (the e xtent of the LES domain c annot b e much lar ger than 10-100 times the boundar y layer thick ness par allel t o the w all). For this r eason the use of LES is only r ecommended for flo ws wher e wall b oundar y layers ar e not r elevant and need not b e resolv ed or f or flo ws wher e the b oundar y layers ar e laminar due t o the lo w Reynolds numb er. In such c ases , the most balanc ed LES mo del is the WALE mo del (see Wall-A dapting L ocal Eddy-Viscosity (WALE) M odel in the Theor y Guide ). It off ers a go od compr omise b etween mo del c omple xity and gener ality. It also allo ws computing laminar shear (b oundar y) la yers without an y mo del impac t. An extension t o LES is Wall-M odeled LES ( WMLES). It allo ws the LES c omputa tion of w all b ounded flows at higher R eynolds numb er without the lar ge incr ease in gr id resolution r equir ed f or c onven- tional LES a t high R eynolds numb ers. For WMLES, the gr id resolution is lar gely indep enden t of the Reynolds numb er with r espect to the gr id cells r equir ed p er b oundar y layer v olume . An enhanc ed version of WMLES c alled WMLES - is also a vailable .WMLES do es not pr ovide z ero edd y-visc osity for flo ws with c onstan t shear .Therefore, it do es not allo w the c omputa tion of tr ansitional eff ects, and can pr oduce overly lar ge edd y-visc osities in separ ating shear la yers.The enhanc ed WMLES - for- mula tion o vercomes these deficiencies . See Algebr aic Wall-M odeled LES M odel ( WMLES) in the Theor y Guide for fur ther details . 12.2.2.2. Hybrid R ANS-LES Mo dels In or der t o avoid the high r esolution r equir emen ts of LES, numer ous h ybrid mo dels ha ve been de- velop ed in r ecent years .These ar e mo dels tha t combine c ertain elemen ts of R ANS and LES appr oaches in a w ay tha t allo ws for the simula tion of high R eynolds numb er flo ws.With h ybrid mo dels , the a t- tached w all b oundar y layers ar e typic ally c overed b y the R ANS par t of the mo del, while lar ge detached regions ar e handled in ‘LES ’ mo de, meaning with a par tial r esolution of the turbulen t sp ectrum in spac e and time . Hybrid mo dels r ely on a str ong enough flo w instabilit y to gener ate turbulen t str uctures in the separ ated z one .This is t ypic ally the c ase f or flo ws behind bluff b odies , wher e UR ANS mo dels predic t single-mo de p eriodic v ortex shedding . Hybrid mo dels allo w these v ortices to gener ate smaller eddies do wn t o the a vailable gr id limit. Figur e 12.5: Illustr ation of SST-UR ANS v s. SST-SAS M odels (p.1386 ) shows a t ypic al sc enar io:While the applic ation of a standar d RANS mo del in unst eady mo de r esults in a single fr equenc y vortex shedding (lef t), the applic ation of h ybrid mo dels allo ws a br eak-up of the lar ge str uctures in to smaller sc ales .This is b eneficial f or pr edic ting the c orrect mixing b ehind the body or t o extract sp ectral inf ormation (f or e xample , for ac oustic simula tions). At the same time , the wall b oundar y layers ar e covered b y the R ANS par t of the h ybrid mo del a voiding the e xcessiv e resol- ution r equir emen ts of LES. 1385Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Choosing a Turbulenc e ModelFigur e 12.5: Illustr ation of SST-UR ANS v s. SST-SAS M odels Figur e 12.5: Illustr ation of SST-UR ANS v s. SST-SAS M odels (p.1386 ) sho ws a cir cular c ylinder in a cr oss flow at .The lef t hand side illustr ates the SST-UR ANS mo del, while the r ight-hand side illustr ates the SST-SAS mo del. The isosur face of is c olor ed acc ording t o the edd y visc osity ratio (not e tha t the sc ale in the r ight-hand side figur e is smaller b y a fac tor of 14). 12.2.2.2.1. Scale-A daptiv e Simulation (SAS) The SAS mo deling appr oach (see Scale-A daptiv e Simula tion (SAS) M odel in the Theor y Guide ) as proposed b y Menter et al. ([77] (p.4009 )[78] (p.4009 )) is based on the in troduc tion of the v on K arman length sc ale, , into the turbulenc e equa tions (f or the BSL and SST mo dels , it en ters in to the -equa tion). is defined as the r atio of the first divided b y the sec ond der ivative of the v elocity vector (times the v on K arman c onstan t =0.41): (12.1) The inclusion of this t erm allo ws the mo del t o adjust its length sc ale t o alr eady resolv ed sc ales in the flo w and ther eby pr ovide a lo w enough edd y visc osity to allo w the mo del t o op erate in ‘LES ’ mode. The SAS appr oach has the ad vantage tha t the R ANS par t of the mo del is unaff ected b y the gr id spacing and will ther efore not allo w a det erioration of mo del accur acy as seen in DES in r egions of refined gr id but insufficien t flo w instabilit y. However, in c ases wher e the flo w instabilit y is not str ong enough, the SAS will r emain in R ANS mo de and will not pr oduce unst eady str uctures.While this is often a sign tha t the R ANS mo del is still r easonably c apable of handling the flo w, it is a limita tion if unst eady inf ormation is r equir ed (f or e xample , in ac oustics). In such c ases , the in ternal in terface option of the ELES implemen tation c an b e applied t o convert mo deled turbulenc e in to resolv ed turbulenc e (see Internal In terface Without LES Z one in the Theor y Guide) . 12.2.2.2.2. Detached E ddy S imulation (DES) The DES mo del (see Detached E ddy Simula tion (DES) in the Theor y Guide ) achie ves the swit ch between R ANS and LES b y a c ompar ison of the turbulen t length sc ale with the gr id spacing . The mo del selec ts the minimum of b oth and ther eby swit ches b etween R ANS and LES mo de b y re- placing in the -equa tion b y: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1386Modeling Turbulenc e(12.2) Onc e the mo del selec ts the gr id spacing as the minimum, the mo del is op erating in ‘LES ’ mo de. The gr id spacing en ters e xplicitly in to the DES mo del. This c an aff ect the R ANS solution in r egions , wher e the gr id is b etween R ANS and LES r esolution (so-c alled ‘gray zones' in DES) and/or wher e the flow instabilit y is not str ong enough t o gener ate LES str uctures. Another issue t o consider with DES is the pr oblem of ‘grid-induc ed-separ ation ’ (GIS). It occurs if the gr id for an a ttached w all b oundar y layer flo w is r efined t o a p oint wher e the DES limit er b ecomes ac tive and aff ects the R ANS solution. However, in such situa tions , the flo w instabilit y is not str ong enough t o balanc e the r educ ed R ANS content by resolv ed turbulenc e.This will t ypic ally r esult in an ar tificial flo w separ ation a t the lo cation of gr id refinemen t. It typic ally happ ens if ( being the b oundar y layer thick ness). Remedies for this situa tion ha ve been pr oposed b y Menter et al. who r ecommended using the F1 blending func tion of the SST-DES mo del t o shield the b oundar y layers fr om the DES limit er. Later, alternative blending func tions f or the same pur pose ha ve been pr oposed b y Spalar t et al. ([109] (p.4011 ))—r es- ulting in the t erminolo gy Delayed DES (DDES). The DDES mo del as or iginally pr oposed f or the S palar t- Allmar as mo del pr ovided limit ed pr otection against GIS f or two-equa tion mo dels such as BSL, SST , and - .Therefore, the DDES func tion has b een r e-calibr ated f or the BSL, SST , and - mo dels and is no w the r ecommended choic e and the default setting when using these mo dels . A fur ther r efinemen t is pr ovided b y the Impr oved DDES (IDDES) f ormula tion of S trelets et al. ([115] (p.4011 )), which e xtends the LES z one of the mo del t o the out er par t of w all b oundar y layers. This allo ws the simula tion of w all b oundar y layers in Wall-M odeled LES ( WMLES) mo de. In this model, the IDDES mo del is applied lik e a LES mo del, typic ally with the sp ecific ation of unst eady inlet conditions .The gr id resolution r equir emen ts for WMLES ar e much less str ingen t than f or LES. All of the ab ove shielding func tion v ariants ar e available in ANSY S Fluen t. For the S palar t-Allmar as model, the or iginal DDES shielding func tion is used . For the - , BSL, and SST mo dels , the DDES func tion has b een r e-calibr ated f or b etter b oundar y layer pr otection. The r e-calibr ated DDES func tion is the default selec tion and is r ecommended o ver the use of the F1 or F2 func tions f or the BSL / SST model. Despit e the p otential difficulties in the applic ation of h ybrid metho ds, the y ha ve the p otential to gr eatly e xpand the usage of Sc ale-R esolving S imula tion mo dels f or engineer ing applic ations , as they avoid the e xcessiv e resolution r equir ed b y LES f or w all b oundar y layers. IDDES in WMLES mo de is an ad vanced option and should only b e used if y ou ar e familiar with the or iginal lit erature and the gr id requir emen ts for this mo del. The DES and DDES mo dels in ANSY S Fluen t ha ve been sup erseded b y the SDES and SBES mo dels descr ibed in Shielded D etached E ddy Simula tion (SDES) and S tress-B lended E ddy Simula tion (SBES) (p.1387 ). 12.2.2.2.3. Shielded D etached E ddy S imulation (SDES) and Str ess-Blended E ddy S imulation (SBES) The S hielded D etached E ddy Simula tion (SDES) mo del and the S tress-B lended E ddy Simula tion (SBES) model ar e hybrid R ANS-LES mo dels with an impr oved shielding func tion c ompar ed t o DDES / IDDES. They pr ovide str ong shielding of the R ANS b oundar y layer, fast er “transition ” from R ANS t o LES in separ ating shear la yers, and (f or SBES) e xplicit selec tion of the LES mo del. For implemen tation details , see Shielded D etached E ddy Simula tion (SDES) and Stress-B lended E ddy Simula tion (SBES) in the Theor y Guide ; for setup details , see Including the SDES or SBES M odel with BSL, SST , and Transition SST M odels (p.1444 ). 1387Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Choosing a Turbulenc e ModelThese mo dels ar e recommended o ver the older DES / DDES mo del f ormula tions .The SBES mo del is consider ed the optimal selec tion, as it off ers the clear est distinc tion b etween R ANS and LES z ones . 12.2.2.3. Zonal Mo deling and E mb edded LES (ELES) As pointed out in the pr evious sec tions , hybrid mo dels r ely on flo w instabilities t o gener ate turbulen t structures in lar ge separ ated r egions without the e xplicit in troduc tion of unst eadiness thr ough the boundar y conditions . However, ther e ar e situa tions , wher e such instabilities ar e not pr esen t or ar e not r eliable t o ser ve this pur pose. In such c ases , it is desir able t o apply R ANS and the LES mo dels in predefined z ones and pr ovide clear ly defined in terfaces b etween them. At these in terfaces, the modeled turbulen t kinetic ener gy from the upstr eam R ANS mo del is c onverted e xplicitly t o resolv ed scales a t an in ternal b oundar y to the LES z one .The LES z one c an then b e limit ed t o the r egion of interest wher e unst eady results ar e requir ed. ELES is a vailable in ANSY S Fluen t and allo ws the c om- bina tion of most R ANS mo del with classic al LES mo dels . It is imp ortant to emphasiz e tha t in this mode, a full LES r esolution is r equir ed within the LES z one . In the LES z one , using the WALE mo del is recommended (see Wall-A dapting L ocal Eddy-Viscosity (WALE) M odel in the Theor y Guide ). 12.2.3. Grid Resolution SRS M odels Grid R esolution SRS mo dels ar e discussed in the f ollowing sec tions: 12.2.3.1. Wall B oundar y La yers 12.2.3.2. Free S hear F lows 12.2.3.1. Wall B oundar y Layers For w all b oundar y layers, it is imp ortant to distinguish if the y are comput ed in R ANS or w all-r esolv ed or Wall-M odeled LES ( WMLES) mo de. Only the IDDES and the SBES mo del c an b e run in WMLES mo de reliably . In the c ase of R ANS mo de, the r equir emen ts ar e the same as f or an y RANS mo del. For a w all-r esolv ed LES, it is t ypic ally r ecommended t o use a mesh with a gr id spacing sc aling with wher e x is the str eamwise , y the w all nor mal and z the spanwise dir ection (f or e xample , channel flo w). However, in c omple x applic ations , the distinc tion b etween str eamwise and spanwise dir ection is not feasible and then would b e requir ed.This sc aling demonstr ates the str ong Reynolds numb er dep endenc y of the LES appr oach f or w all b ounded flo ws. For the IDDES and SBES mo dels in WMLES mo de, the ab ove requir emen ts can b e relax ed.The gr id spacing no longer sc ale with the w all fr iction, but with the b oundar y layer thick ness . It is r ecom- mended tha t you use .The w all nor mal r esolution should b e lik e for a finely resolv ed R ANS simula tion, meaning a near w all resolution of and ar ound 30 no des inside the boundar y layer. 12.2.3.2. Free Shear F lows For fr ee shear flo ws, it is difficult t o pr ovide gener al recommenda tions , as ther e ar e man y diff erent flow sc enar ios.The cur rent recommenda tion is ther efore based on the most c ommon (and most fr e- quen t) free shear flo w – a turbulen t mixing la yer. It will not nec essar ily apply t o other fr ee shear flo ws like jets and y ou ar e ad vised t o perform tests as t o the optimal r esolution of y our sp ecific flo w. For fr ee shear flo ws and SRS mo dels , one should aim f or unif orm isotr opic c ells (all edges ha ve similar length). The shear la yer should b e covered b y ~10-20 c ells. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1388Modeling Turbulenc e12.2.4. Numer ics S ettings f or SRS M odels For Sc ale-R esolving S imula tions (SRS), specific discr etiza tion and solv er settings ar e requir ed t o achie ve optimal accur acy with minimal numer ical eff ort.The r ecommenda tions giv en b elow should b e consider ed as a star ting p oint for y our sp ecific flo w applic ation and ar e not gener ic, but pr oblem dep enden t.The recommenda tions ar e based on inc ompr essible , single phase flo w without chemic al reactions or other comple x additional ph ysics. In c ase y our simula tion f eatures additional c omple x ph ysical eff ects, it re- quir es adjusting the r ecommended solv er settings acc ordingly . In most c ases , this will mean tha t a higher eff ort must b e invested in to the c oupling of the equa tions (f or e xample lo wer time st ep, reduc ed under-r elaxa tion, higher it eration c oun t, smaller r esiduals), in or der t o avoid a de-c oupling of diff erent physical phenomena. For Sc ale-R esolving S imula tions , optimal numer ics settings ar e essen tial f or achie ving accur ate results in an acc eptable time fr ame .The r eason is tha t at the SRS mo dels op erate at the r esolution limit of the pr ovided gr id wher e the smallest sc ales ar e of the or der of the gr id spacing and the time r esolution. Numer ics settings ther efore ha ve to be chosen t o pr ovide an optimal balanc e between accur acy and robustness . It is gener ally r ecommended t o initializ e the solution fr om a (r easonably) c onverged R ANS simula tion. 12.2.4.1. Time D iscr etization For Sc ale-R esolving S imula tions , the r esolution of the turbulen t str uctures in time is essen tial f or the succ ess of the simula tion. This is , to the lar gest e xtent, defined b y the selec ted time st ep. As the SRS model is op erating a t the gr id limit , you should selec t a time st ep tha t ensur es a C ourant-Friedr ichs- Levy (CFL) numb er of (12.3) The CFL numb er is c omput ed b y the solv er and c an b e check ed based on an initial R ANS simula tion, for e xample . It is imp ortant to emphasiz e tha t this is not a numer ical limit and tha t the solv er will b e able t o sustain much lar ger CFL numb ers. In c omple x applic ations , ther e will alw ays be limit ed r egions of fine c ells or lar ge v elocities and y ou should not r estrict the CFL numb er based on such z ones .The recommenda tion of CFL =1 should b e applied in the main SRS r egion in c ombina tion with a unif orm isotr opic gr id. It is r ecommended tha t you v ary the time st ep f or each t ype of applic ation and e xplor e its optimal v alue .This c an substan tially sa ve on c omputing c osts . The time der ivative should b e comput ed b y the S econd Or der Implicit option. (See User Inputs f or Time-D ependen t Problems (p.2627 ) for guidelines on setting solution par amet ers f or tr ansien t calcula- tions in gener al.) 12.2.4.2. Spatial D iscr etization For SRS mo dels , it is imp ortant to minimiz e the numer ical dissipa tion of the scheme in or der t o avoid damping of the smallest sc ales b y numer ical dissipa tion. For the pr essur e-based solv er, the choic e for spa tial discr etiza tion is b etween the C entral D ifferencing (CD) scheme (see Central-D ifferencing Scheme in the Theor y Guide ) and the B ounded C entral D ifferencing scheme (BCD) (see Bounded Central D ifferencing Scheme in the Theor y Guide ); for the densit y-based solv er, BCD is a vailable with the R oe-FDS or A USM flux t ype for the discr etiza tion of the flo w equa tions , but CD is not. The C entral Differencing scheme is the least dissipa tive and pr ovides the highest r esolution accur acy for the smallest sc ales . Especially f or aer o-ac oustics simula tions , wher e the sp ectral content at higher fr equen- cies c an b e imp ortant, this is a desir able f eature. However, Central D ifferencing schemes ar e pr one 1389Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Choosing a Turbulenc e Modelto solution oscilla tions (check er b oarding) in the v elocity field .When using the C entral D ifferencing scheme , it is ther efore imp ortant to pr ovide a high qualit y mesh (no mesh jumps , isotr opic c ells and high r esolution in cr itical zones) and t o avoid lar ge time st eps (the CFL numb er should b e smaller than 1 in the main SRS r egion). It is r ecommended tha t you visually monit or the solution r egular ly in order t o avoid w asting c omputa tional r esour ces. In c ase oscilla tions app ear, the choic e is t o: impr ove the mesh; reduc e the time st ep; or t o swit ch t o the sligh tly mor e dissipa tive, but also mor e robust Bounded C entral D ifferencing scheme . In man y comple x applic ations , the B ounded C entral D ifferencing Scheme is the numer ics option of choic e. It typic ally pr ovides sufficien tly lo w dissipa tion t o allo w the turbulen t str uctures to evolve, but , at the same time , is robust enough t o handle non-optimal gr ids as the y are typic ally enc oun tered in industr ial simula tions . In addition, the B ounded C entral D ifferencing scheme is also suitable f or h ybrid metho ds lik e SAS, DES, SDES, and SBES, and will pr ovide stable solutions in R ANS r egions , with highly str etched gr ids and with a CFL numb er lar ger than 1. For ELES, the numer ical scheme in the LES z one c an b e selec ted indep enden tly fr om the settings in the R ANS zone .The R ANS r egion c an then b e comput ed with standar d higher-or der up wind schemes and the LES z one c an b e covered b y either the C entral D ifferencing scheme or the B ounded C entral D ifferencing scheme . For the gr adien t calcula tion, it is r ecommended tha t you selec t the L east S quar es C ell B ased option, or the G reen-G auss N ode B ased option, to ensur e a sec ond-or der in terpolation on non-or thogonal grids. For pr essur e in terpolation, it is r ecommended tha t you use the sec ond-or der scheme , or the b ody- force-weigh ted scheme . Due t o its higher dissipa tion, the PREST O! scheme (see Pressur e In terpolation Schemes in the Theor y Guide ) can r esult in a dela yed f ormation or damping of turbulen t str uctures. It is ther efore not r ecommended f or SRS. 12.2.4.3. Iterativ e Scheme The selec tion of the it erative scheme will mostly aff ect the c omputa tional c osts as the c ost p er it eration between these metho ds is r ather diff erent. However, recommenda tions ar e not str aigh tforward, as the higher c ost p er it eration of a scheme c an b e off set b y fast er convergenc e within the time st ep. The fast est scheme is the N on-I terative Time A dvancemen t (NIT A) scheme (see Non-I terative Time- Advancemen t Scheme in the Theor y Guide as w ell as Setting S olution C ontrols f or the N on-I terative Solver (p.2575 )).This scheme t ypic ally w orks w ell for limit ed LES z ones and high qualit y meshes . It is also imp ortant to ensur e a lo w time st ep of a CFL numb er b elow 1. For the NIT A scheme , all e xplicit under-r elaxa tion fac tors ar e, by default , set equal t o one .With NIT A, it has sligh t ad vantages t o use the fr actional st ep metho d if ther e is no in volvemen t of mor e comple x ph ysics, when other wise the PISO scheme c an b e mor e beneficial. Note tha t with the LES mo del, you c an enable an acc elerated time mar ching option, which enables a mo dified NIT A scheme and other setting changes tha t can further sp eed up the simula tion; for details , see Setting S olution C ontrols f or the N on-I terative Solv- er (p.2575 ). In case the applic ation is t oo comple x for the NIT A scheme t o pr ovide a solution, the it erative SIMPLEC (SIMPLE v s. SIMPLEC (p.2570 )) or PISO ( PISO (p.2571 )) schemes ar e the ne xt possible option. They should be pr eferred r elative to the SIMPLE scheme , as the y sho w fast er convergenc e per time st ep and c an be run with mor e aggr essiv e under-r elaxa tion (higher v alues equal t o 1 or close t o 1). If such settings prevent convergenc e within the time st ep, then check if y our time st ep is small enough f or main taining CFL numb ers b elow 1 in the SRS r egion – if not , then tr y reducing . If this is not p ossible , or do es not lead t o sa tisfac tory convergenc e, then r educ e the under-r elaxa tion fac tors t o values b etween the default settings and 1. For sk ewed meshes or meshes with pr oblema tic qualit y, the r educ tion of e x- plicit r elaxa tion fac tor for pr essur e correction do wn t o 0.7 fr om 1 c an b e very helpful. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1390Modeling Turbulenc e12.2.4.3.1. Convergenc e Contr ol The c onvergenc e cr iterion within each time st ep will str ongly aff ect solution c osts , as a lo w cr iterion will r esult in an incr eased numb er of it erations . It is not p ossible t o pr ovide gener al recommenda tions , as the r equir ed r esidual dep ends on the applic ation. The most r elevant residual in the SRS mo dels is the c ontinuit y residual. It should b e converged b y appr oxima tely 2 or ders of magnitude p er time step f or a CFL numb er ~ 1. This should b e achie vable with ar ound 5-10 maximum it erations p er time step f or flo ws involving no other ph ysical mo dels . Be sur e to check the impac t of c onvergenc e on your solution t o ensur e tha t the r esidual is r educ ed t o a le vel consist ent with y our pr oblem. For simula tions with small CFL v alues , the Extrapolate Variables option (a vailable in the Run C alcu- lation Task P age (p.3640 )) can b e very beneficial. This c an substan tially r educ e the numb er of it erations within the time st ep up t o 40% when the c onvergenc e control is based on the c onvergenc e cr iteria. In case y our simula tion r equir es the c ombina tion of additional ph ysical mo dels , such as c ombustion or multiphase , a reduc tion of the under-r elaxa tion fac tors migh t be requir ed. In this c ase, the numb er of maximum it erations p er time st ep c an b e incr eased t o achie ve the desir ed r esidual r educ tion. For h ybrid R ANS/LES simula tions , such as the SAS, DES, SDES, and SBES mo dels , ther e can b e situa tions wher e the R ANS p ortion of the flo w limits c onvergenc e (for e xample , due t o poor gr id qualit y). In such c ases , the applic ation of the c oupled solv er should b e consider ed. For the c oupled pr essur e- based solv er, each it eration is t ypic ally mor e expensiv e than f or the SIMPLEC algor ithm, but this is at least par tly off set b y fast er convergenc e.The r ecommenda tions c oncerning r esiduals ar e similar to the SIMPLEC metho d, but the maximal numb er of it erations c an b e reduc ed t o values as lo w as 2-5 f or highly unstable flo ws, and 5-10 f or mor e sensible flo ws and ac oustics simula tions . 12.2.5. Model Hier archy As discussed , turbulenc e mo deling is a balanc e between accur acy and c ost. The r ecommenda tion is to use R ANS mo dels as much as p ossible and as long as the y pr ovide the accur acy requir ed f or the simula tion. RANS mo dels will r emain the w orkhorse of turbulenc e mo deling f or man y years t o come . Within the R ANS family , edd y-visc osity mo dels ar e typic ally sufficien t for most engineer ing flo w simu- lations .The applic ation of RSM is only r ecommended f or flo ws tha t are known t o sy stema tically b enefit from their usage and justify the incr ease in c omputing p ower. In cases wher e steady RANS or UR ANS mo dels c annot pr ovide the accur acy or unst eady inf ormation requir ed, it is r ecommended tha t you swit ch t o the SAS appr oach. It is r elatively f orgiving in t erms of the gr id resolution and will not det eriorate the r esults in c ase of insufficien t resolution in the unst eady zone .The SAS mo del will only pr ovide sc ale-r esolution if a str ong flo w instabilit y is pr esen t.Visual in- spection (using isosur faces of the Q cr iterion) will quick ly allo w a judgmen t if the mo del pr ovides suf- ficien t unst eadiness and r esolution r elative to the gr id spacing . In such c ases , the in ternal in terface option of the ELES implemen tation c an b e applied t o convert mo deled turbulenc e in to resolv ed tur- bulenc e (see Internal In terface Without LES Z one in the Theor y Guide) . DDES (DES is not r ecommended) mo dels c an allo w the f ormation of unst eadiness e ven f or c ases wher e SAS r emains stable . DDES do es requir e a mor e carefully cr afted gr id in the LES z one due t o the DES grid influenc e on the R ANS solution. For the DES-BSL / SST mo del, use the default DDES blending func tion f or shielding . SDES and SBES ha ve an impr oved shielding func tion c ompar ed t o DDES / IDDES. They pr ovide str ong shielding of the R ANS b oundar y layer and demonstr ate a fast “transition ” between R ANS and LES in separ ating shear la yers.The SBES mo del f ormula tion in c ombina tion with the WALE LES mo del is r e- commended o ver older mo dels lik e DES, DDES, and IDDES. 1391Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Choosing a Turbulenc e ModelELES is r ecommended in c ases wher e limit ed z ones with high accur acy requir emen ts ar e emb edded inside a lar ger R ANS z one . At the in terface between the R ANS and the LES z one , unst eady turbulenc e is gener ated either b y the Vortex Metho d or the S pectral Synthesiz er. For w all b ounded flo ws, the ELES metho d requir es a v ery fine near w all resolution in the LES z one . Pure LES should only b e applied t o free shear flo ws (for e xample , combustion chamb ers without w all influenc e) or t o very limit ed domains using meshes with fine LES near w all resolution. It is imp ortant to be aware of the str ong incr ease of gr id resolution r equir emen ts with R eynolds numb er for w all bounded flo ws. For w all b oundar y layers a t higher R eynolds numb ers, the IDDES mo del c an b e run in WMLES mo de – meaning with sp ecified unst eady inlet c onditions . 12.3. Steps in U sing a Turbulenc e M odel When y our ANSY S Fluen t mo del includes turbulenc e you need t o enable the r elevant mo del and options , and supply turbulen t boundar y conditions .These inputs ar e descr ibed in this sec tion. The pr ocedur e for setting up a turbulen t flo w pr oblem is descr ibed b elow. (Note tha t this pr ocedur e includes only those st eps nec essar y for the turbulenc e mo del itself ; you will need t o define the other settings—f or e xample , other mo dels , boundar y conditions—as usual.) 1.Define the turbulenc e mo del settings . a.Open the Viscous M odel D ialog Box (p.3253 ) (Figur e 12.6: The Viscous M odel D ialog Box (p.1393 )) by right- click ing Visc ous in the tr ee (under Setup/M odels ) and click ing Edit... in the menu tha t op ens. Setup → Models → Visc ous Edit... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1392Modeling Turbulenc eFigur e 12.6: The Visc ous M odel D ialo g Box b.Selec t either Spalar t-Allmar as,k-epsilon ,k-omega ,Transition k-k l-omega ,Transition SST ,Reynolds Stress,Scale-A daptiv e Simula tion (SAS) ,Detached E ddy Simula tion (DES) , or Large E ddy Simula tion (LES) from the Model list. 1393Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Steps in U sing a Turbulenc e ModelIf you cho ose the k-epsilon mo del, selec t either Standar d,RNG , or Realizable from the k-epsilon Model list. If you cho ose the k-omega mo del, selec t Standar d,BSL , or SST from the k-omega Model list. Imp ortant The Large E ddy Simula tion (LES) mo del is a vailable only f or 3D c ases . c.If the flo w in volves w alls, and y ou ar e using one of the - mo dels or the -based R eynolds str ess models , cho ose one of the f ollowing options fr om the Near-W all Treatmen t list in the Visc ous M odel dialo g box: •Standar d Wall F unc tions •Scalable Wall F unc tions •Non-E quilibr ium Wall F unc tions •Enhanc ed Wall Treatmen t •Menter-L echner (for - mo dels only) •User-D efined Wall F unc tions For mor e inf ormation ab out these near-w all options , see Near-W all Treatmen ts for Wall-B ounded Turbulen t Flows in the Theor y Guide . By default , the standar d w all func tion is enabled . For mor e inf ormation ab out the aut oma tically defined near-w all tr eatmen t for the S palar t-Allmar as model, see Wall B oundar y Conditions in the Theor y Guide . For mor e inf ormation ab out the aut oma tically defined near-w all tr eatmen t for the - mo del, see Wall B oundar y Conditions in the Theor y Guide . For mor e inf ormation ab out the aut oma tically defined near-w all tr eatmen t and the optional Werner-W engle near-w all tr eatmen t for the LES mo del, see Inlet B oundar y Conditions f or Sc ale Resolving S imula tions and LES N ear-W all Treatmen t in the Theor y Guide , respectively. d.Enable the other appr opriate turbulenc e mo deling options in the Visc ous M odel dialo g box, as appr o- priate. See Setup Options f or A ll Turbulenc e Modeling (p.1436 ) 2.Specify the b oundar y conditions f or the solution v ariables in the appr opriate boundar y condition dialo g boxes.The b oundar y condition dialo g boxes c an b e op ened b y right-click ing the b oundar y name in the tree (under Setup/B oundar y Conditions ) and click ing Edit... in the menu tha t op ens; alternatively, you can op en them fr om the Boundar y Conditions task page: Setup → Boundar y Conditions See Defining Turbulenc e Boundar y Conditions (p.1448 ) for details . 3.Specify the initial guess f or the solution v ariables in the Solution Initializa tion task page . Solution → Initializa tion Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1394Modeling Turbulenc eSee Providing an Initial G uess f or k and ε (or k and ω) (p.1452 ) for details . Note tha t Reynolds str esses are aut oma tically initializ ed using , and ther efore need not b e initializ ed e xplicitly . 12.4. Setting U p the S palar t-Allmar as M odel If you cho ose the S palar t-Allmar as mo del, the f ollowing options ar e available: •vorticit y-based pr oduc tion ( Vorticit y- and S train/V orticit y-Based P roduc tion (p.1439 )) •strain/v orticit y-based pr oduc tion ( Vorticit y- and S train/V orticit y-Based P roduc tion (p.1439 )) •viscous hea ting (alw ays enabled f or the densit y-based solv ers) ( Including the Viscous H eating E ffects (p.1437 )) •curvature correction ( Including the C urvature Correction f or the S palar t-Allmar as and Two-Equa tion Turbu- lenc e Models (p.1437 )) Figur e 12.7: The Visc ous M odel D ialo g Box Displa ying the S palar t-Allmar as P roduc tion 12.5. Setting U p the k- ε Model For additional inf ormation, see the f ollowing sec tions: 1395Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the k- ε Model12.5.1. Setting U p the S tandar d or R ealizable k- ε Model 12.5.2. Setting U p the RNG k- ε Model 12.5.1. Setting U p the S tandar d or Realizable k- ε Model If you cho ose the standar d - mo del or the r ealizable - mo del, the f ollowing options ar e available: •viscous hea ting (alw ays enabled f or the densit y-based solv ers) ( Including the Viscous H eating E ffects (p.1437 )) •inclusion of buo yancy eff ects on (see Effects of B uoyancy on Turbulenc e in the k- ε Models in the Theor y Guide ) •inclusion of cur vature correction ( Including the C urvature Correction f or the S palar t-Allmar as and Two- Equa tion Turbulenc e Models (p.1437 )) •inclusion of c ompr essibilit y eff ects (Including the C ompr essibilit y Effects Option (p.1438 )) •inclusion of pr oduc tion limit ers ( Including P roduc tion Limit ers f or Two-Equa tion M odels (p.1438 )) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1396Modeling Turbulenc eFigur e 12.8: The Visc ous M odel D ialo g Box Displa ying the S tandar d k-ε Model For all - mo dels , one of the f ollowing near-w all tr eatmen ts must b e selec ted (see Near-W all Treatmen ts for Wall-B ounded Turbulen t Flows in the Theor y Guide ): •standar d wall func tions •scalable w all func tions 1397Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the k- ε Model•non-equilibr ium w all func tions •enhanc ed w all tr eatmen t •Menter-L echner •user-defined w all func tions If you cho ose the enhanc ed w all tr eatmen t, the f ollowing options ar e available: •pressur e gr adien t eff ects (Including P ressur e Gradien t Effects (p.1441 )) •ther mal eff ects (Including Thermal E ffects (p.1441 )) If you selec t user-defined w all func tions f or the near-w all tr eatmen t, hook y our UDF using the Law of the Wall drop-do wn list tha t app ears a t the b ottom of the User-D efined F unc tions group b ox in the Visc ous M odel dialo g box. 12.5.2. Setting U p the RNG k- ε Model If you cho ose the RNG - mo del, the f ollowing options ar e available: •differential visc osity mo del ( Differential Viscosity Modific ation (p.1440 )) •swir l mo dific ation ( Swirl Modific ation (p.1440 )) •viscous hea ting (alw ays enabled f or the densit y-based solv ers) ( Including the Viscous H eating E ffects (p.1437 )) •inclusion of buo yancy eff ects on (see Effects of B uoyancy on Turbulenc e in the k- ε Models in the Theor y Guide ) •inclusion of cur vature correction ( Including the C urvature Correction f or the S palar t-Allmar as and Two- Equa tion Turbulenc e Models (p.1437 )) •inclusion of c ompr essibilit y eff ects (Including the C ompr essibilit y Effects Option (p.1438 )) •inclusion of pr oduc tion limit ers ( Including P roduc tion Limit ers f or Two-Equa tion M odels (p.1438 )) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1398Modeling Turbulenc eFigur e 12.9: The Visc ous M odel D ialo g Box Displa ying the RNG k- ε Model 1399Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the k- ε ModelRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1400Modeling Turbulenc eFor all - mo dels , one of the f ollowing near-w all tr eatmen ts must b e selec ted (see Near-W all Treatmen ts for Wall-B ounded Turbulen t Flows in the Theor y Guide ): •standar d wall func tions •scalable w all func tions •non-equilibr ium w all func tions •enhanc ed w all tr eatmen t •Menter-L echner •user-defined w all func tions If you cho ose the enhanc ed w all tr eatmen t, the f ollowing options ar e available: •pressur e gr adien t eff ects (Including P ressur e Gradien t Effects (p.1441 )) •ther mal eff ects (Including Thermal E ffects (p.1441 )) If you selec t user-defined w all func tions f or the near-w all tr eatmen t, hook y our UDF using the Law of the Wall drop-do wn list tha t app ears a t the b ottom of the User-D efined F unc tions group b ox in the Visc ous M odel dialo g box. 12.6. Setting U p the k- ω Model For additional inf ormation, see the f ollowing sec tions: 12.6.1. Setting U p the S tandar d k-ω Model 12.6.2. Setting U p the B aseline (BSL) k- ω Model 12.6.3. Setting U p the S hear-S tress Transp ort k-ω Model 12.6.4. Setting up the G ener alized k-ω (GEK O) M odel 12.6.1. Setting U p the S tandar d k-ω Model If you cho ose the standar d - mo del, the f ollowing options ar e available: •low-R e corrections ( Low-R e Corrections (p.1440 )) •shear flo w corrections ( Shear F low Corrections (p.1440 )) •turbulenc e damping (a vailable with the VOF and M ixture mo dels and the E uler ian multiphase mo del when using the M ulti-F luid VOF mo del) ( Turbulenc e Damping (p.1441 )) •viscous hea ting (alw ays enabled f or the densit y-based solv ers) ( Including the Viscous H eating E ffects (p.1437 )) •inclusion of cur vature correction ( Including the C urvature Correction f or the S palar t-Allmar as and Two- Equa tion Turbulenc e Models (p.1437 )) •inclusion of c ompr essibilit y eff ects (Including the C ompr essibilit y Effects Option (p.1438 )) •inclusion of pr oduc tion limit ers ( Including P roduc tion Limit ers f or Two-Equa tion M odels (p.1438 )) 1401Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the k- ω Model•a scale-r esolving simula tion option: Scale-A daptiv e Simula tion ( Setting U p Sc ale-A daptiv e Simula tion (SAS) Modeling (p.1418 )) Figur e 12.10: The Visc ous M odel D ialo g Box Displa ying the S tandar d k-ω Model The - mo dels use -insensitiv e near-w all tr eatmen t (see y+-Insensitiv e Wall Treatmen t ω-Equa tion in the Theor y Guide ). 12.6.2. Setting U p the B aseline (BSL) k- ω Model If you cho ose the baseline (BSL) - mo del, the f ollowing options ar e available: •low-R e corrections ( Low-R e Corrections (p.1440 )) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1402Modeling Turbulenc e•turbulenc e damping (a vailable with the VOF and M ixture mo dels and the E uler ian multiphase mo del when using the M ulti-F luid VOF mo del) ( Turbulenc e Damping (p.1441 )) •viscous hea ting (alw ays enabled f or the densit y-based solv ers) ( Including the Viscous H eating E ffects (p.1437 )) •inclusion of cur vature correction ( Including the C urvature Correction f or the S palar t-Allmar as and Two- Equa tion Turbulenc e Models (p.1437 )) •inclusion of c ompr essibilit y eff ects (Including the C ompr essibilit y Effects Option (p.1438 )) •inclusion of pr oduc tion limit ers ( Including P roduc tion Limit ers f or Two-Equa tion M odels (p.1438 )) •inclusion of the In termitt ency Transition mo del •scale-r esolving simula tion options: either Sc ale-A daptiv e Simula tion ( Setting U p Sc ale-A daptiv e Simula tion (SAS) M odeling (p.1418 )), Detached E ddy Simula tion ( Setting U p DES with the Transition SST M odel (p.1427 )), Stress-B lended E ddy Simula tion ( Including the SDES or SBES M odel with BSL, SST , and Transition SST Models (p.1444 )), or S hielded D etached E ddy Simula tion ( Including the SDES or SBES M odel with BSL, SST , and Transition SST M odels (p.1444 )). 1403Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the k- ω ModelFigur e 12.11: The Visc ous M odel D ialo g Box Displa ying the BSL k- ω Model 12.6.3. Setting U p the S hear-S tress Transp ort k-ω Model If you cho ose the shear-str ess tr ansp ort - mo del, the f ollowing options ar e available: •low-R e corrections ( Low-R e Corrections (p.1440 )) •turbulenc e damping (a vailable with the VOF and M ixture mo dels and the E uler ian multiphase mo del when using the M ulti-F luid VOF mo del) ( Turbulenc e Damping (p.1441 )) •viscous hea ting (alw ays enabled f or the densit y-based solv ers) ( Including the Viscous H eating E ffects (p.1437 )) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1404Modeling Turbulenc e•inclusion of cur vature correction ( Including the C urvature Correction f or the S palar t-Allmar as and Two- Equa tion Turbulenc e Models (p.1437 )) •inclusion of c ompr essibilit y eff ects (Including the C ompr essibilit y Effects Option (p.1438 )) •inclusion of pr oduc tion limit ers ( Including P roduc tion Limit ers f or Two-Equa tion M odels (p.1438 )) •inclusion of the In termitt ency Transition mo del •scale-r esolving simula tion options: Stress-B lended E ddy Simula tion or S hielded D etached E ddy Simula tion (Including the SDES or SBES M odel with BSL, SST , and Transition SST M odels (p.1444 )). Figur e 12.12: The Visc ous M odel D ialo g Box Displa ying the SST k- ω Model 1405Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the k- ω Model12.6.4. Setting up the G ener aliz ed k-ω (GEK O) M odel To enable the GEK O turbulenc e mo del, you must selec t the k-omega (2 eqn) mo del on the Viscous Model dialo g box and then selec t GEK O in the k-omega M odel group b ox. If you in tend t o combine the GEK O mo del with a R eynolds S tress M odel, you must first selec t one of the f ollowing mo dels: •Reynolds S tress M odel based on BSL equa tion (S tress-BSL) •Wallin-J ohansson Explicit A lgebr aic R eynolds S tress M odel ( WJ-BSL-EARSM, beta f eature) You c an then enable the GEK O option in the Options group b ox of the Viscous M odel dialo g box. In most c ases , you w ould only tune the c oefficien ts and . 1.Optimiz e the c oefficien t for the separ ation char acteristics of w all b oundar y layers, which in most applic ations has the str ongest impac t on p erformanc e. 2.Adjust to aff ect the mixing b ehavior of fr ee shear flo ws (free mixing la yers, etc.). For mor e details r egar ding these c oefficien ts, see Gener alized k-ω (GEK O) M odel (p.1379 ) and Gener alized k-ω (GEK O) M odel in the Fluent Theor y Guide . As these c oefficien ts ar e both a vailable thr ough UDF , you c an also adjust them diff erently in diff erent parts of the domain. The other t wo par amet ers c an, in most c ases , be lef t to their default settings . By default , the full mo del is enabled and giv es acc ess t o all mo del c oefficien ts and the blending func tion in the GEK O Options group b ox (Figur e 12.13: The Viscous M odel D ialog Box with GEK O Options f or the F ull M odel (p.1408 )). For the w all distanc e free mo del option, only a subset of mo del coefficien ts can b e used ( Figur e 12.14: The Viscous M odel D ialog Box with GEK O Options f or the Wall Distanc e Free Version (p.1409 )). The c orresponding t ext command t o enable the GEK O turbulenc e mo del is /define/models/viscous/kw-geko? For c ombina tion with R eynolds str ess mo dels y ou must first enable the c orresponding R eynolds S tress Model and then use the TUI c ommand . /define/models/viscous/rsm-or-earsm-geko-option? After GEK O is enabled , all mo del c oefficien ts and the blending func tion ar e available in the submenu geko-options : /define/models/viscous/geko-options/wall-distance-free? /define/models/viscous/geko-options/csep /define/models/viscous/geko-options/cnw /define/models/viscous/geko-options/cmix /define/models/viscous/geko-options/cjet Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1406Modeling Turbulenc e/define/models/viscous/geko-options/blending-function The auxiliar y coefficien ts ar e also a vailable as TUI c ommands . /define/models/viscous/geko-options/creal /define/models/viscous/geko-options/cnw_sub /define/models/viscous/geko-options/cjet_aux /define/models/viscous/geko-options/cbf_lam /define/models/viscous/geko-options/cbf_tur Further mor e, it is p ossible t o reset these mo del par amet ers t o default v alues b y click ing GEK O D efaults or the TUI c ommand: /define/models/viscous/geko-options/geko-defaults 1407Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the k- ω ModelFigur e 12.13: The Visc ous M odel D ialo g Box with GEK O Options f or the F ull M odel Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1408Modeling Turbulenc eFigur e 12.14: The Visc ous M odel D ialo g Box with GEK O Options f or the Wall D istanc e Free Version 12.7. Setting U p the Transition k-k l-ω Model If you cho ose the Transition - - mo del, it is not nec essar y to mo dify an y of the mo del c onstan ts. 12.8. Setting U p the Transition SST M odel If you cho ose the Transition SST mo del (also k nown as the - mo del), the f ollowing options ar e available: •roughness c orrelation ( Transition SST and R ough Walls in the Theor y Guide ) •viscous hea ting (alw ays enabled f or the densit y-based solv ers) ( Including the Viscous H eating E ffects (p.1437 )) 1409Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the Transition SST M odel•inclusion of cur vature correction ( Including the C urvature Correction f or the S palar t-Allmar as and Two- Equa tion Turbulenc e Models (p.1437 )) •inclusion of pr oduc tion limit ers ( Including P roduc tion Limit ers f or Two-Equa tion M odels (p.1438 )) •scale-r esolving simula tion options: either Sc ale-A daptiv e Simula tion ( Setting U p Sc ale-A daptiv e Simula tion (SAS) M odeling (p.1418 )), Detached E ddy Simula tion ( Setting U p DES with the Transition SST M odel (p.1427 )), Stress-B lended E ddy Simula tion ( Including the SDES or SBES M odel with BSL, SST , and Transition SST M od- els (p.1444 )), or S hielded D etached E ddy Simula tion ( Including the SDES or SBES M odel with BSL, SST , and Transition SST M odels (p.1444 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1410Modeling Turbulenc eFigur e 12.15: The Visc ous M odel D ialo g Box for the Transition SST M odel You c an cust omiz e your tr ansition c orrelations , which ar e used in c onjunc tion with the Transition SST model. The user-defined func tions tha t you c an ho ok ar e: •transition length func tion ( F_length ). 1411Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the Transition SST M odel•critical momen tum thick ness R eynolds numb er (Re_thetac ). •transition onset momen tum thick ness R eynolds numb er (Re_theta t). For detailed inf ormation ab out the tr ansition c orrelation UDFs , see DEFINE_TRANS UDFs in the Fluen t Customiza tion M anual . 12.9. Setting U p the In termitt enc y Transition M odel The In termitt ency Transition mo del (also k nown as the mo del) is a vailable as an option f or the f ollowing turbulenc e mo dels: •BSL - mo del •SST - mo del •Scale-A daptiv e Simula tion with BSL / SST •Detached E ddy Simula tion with BSL / SST •Shielded D etached E ddy Simula tion (SDES) with BSL or SST •Stress-B lended E ddy Simula tion (SBES) with BSL / SST To apply it in c ombina tion with one of these turbulenc e mo dels , you must enable the Intermitt enc y Transition M odel option fr om the Options group b ox in the Visc ous M odel dialo g box. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1412Modeling Turbulenc eFigur e 12.16: The In termitt enc y Transition M odel in C ombina tion with the SST k- ω Model After y ou ha ve enabled the In termitt ency Transition mo del, the additional option Include C rossflo w Transition will b e available .This additional option allo ws you t o include the eff ects of cr ossflo w instabilit y. 12.10. Setting U p the Re ynolds S tress M odel If you cho ose the RSM, the f ollowing submo dels ar e available: • -based R eynolds str ess mo dels: –linear pr essur e-str ain mo del (see Linear P ressur e-Strain M odel in the Theor y Guide ) 1413Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the R eynolds S tress M odel–quadr atic pr essur e-str ain mo del (see Quadr atic P ressur e-Strain M odel in the Theor y Guide ) • -based R eynolds str ess mo dels: –Stress-Omega (see Stress-Omega M odel in the Theor y Guide ) –Stress-BSL (see Stress-BSL M odel in the Theor y Guide ) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1414Modeling Turbulenc eFigur e 12.17: The Visc ous M odel D ialo g Box Displa ying the Re ynolds S tress M odel Options The f ollowing options ar e sp ecific t o the R eynolds-str ess mo dels based on the -equa tion: 1415Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the R eynolds S tress M odel•wall b oundar y conditions f or the R eynolds str esses fr om the equa tion ( Solving the k E qua tion t o Obtain Wall B oundar y Conditions (p.1442 )) for the linear and quadr atic pr essur e-str ain mo dels •wall reflec tion eff ects on R eynolds str esses ( Including the Wall R eflec tion Term (p.1441 )) for the linear pr essur e- strain mo del •near-w all tr eatmen ts (see Near-W all Treatmen ts for Wall-B ounded Turbulen t Flows in the Theor y Guide ): –standar d wall func tions –scalable w all func tions –non-equilibr ium w all func tions –enhanc ed w all tr eatmen t (only f or the linear pr essur e-str ain mo del) If you cho ose the enhanc ed w all tr eatmen t, the f ollowing options ar e available: •pressur e gr adien t eff ects (Including P ressur e Gradien t Effects (p.1441 )) •ther mal eff ects (Including Thermal E ffects (p.1441 )) For the R eynolds str ess mo dels based on the - (Stress-Omega ) and BSL-equa tion ( Stress-BSL ), a near- wall tr eatmen t is aut oma tically used t o perform a blending b etween the visc ous subla yer and the lo g- arithmic r egion, and ther efore near-w all tr eatmen t options ar e not sho wn. A lo w Re-numb er (LRN) mesh is recommended f or these mo dels . For Stress-Omega , you do ha ve the option of selec ting an y or all of the f ollowing options: •low-R e corrections ( Low-R e Corrections (p.1440 )) •shear flo w corrections ( Shear F low Corrections (p.1440 )) For b oth Stress-Omega and Stress-BSL , the f ollowing sc ale-r esolving simula tion option is a vailable: Scale-A daptiv e Simula tion ( Setting U p Sc ale-A daptiv e Simula tion (SAS) M odeling (p.1418 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1416Modeling Turbulenc eFigur e 12.18: The Visc ous M odel D ialo g Box Displa ying the S tress-Omega M odel Options Other options tha t are available f or b oth - and -based R eynolds str ess mo dels dep ending on y our case setup include: •viscous hea ting (alw ays enabled f or the densit y-based solv ers) ( Including the Viscous H eating E ffects (p.1437 )) •inclusion of c ompr essibilit y eff ects (Including the C ompr essibilit y Effects Option (p.1438 )) •inclusion of buo yancy eff ects on (see Effects of B uoyancy on Turbulenc e in the k- ε Models in the Theor y Guide ) Note The -based R eynolds str ess mo dels ar e not c ompa tible with the E uler ian multiphase mo del. 1417Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the R eynolds S tress M odel12.11. Setting U p Sc ale-A daptiv e Simula tion (SAS) M odeling Scale-A daptiv e Simula tion (SAS) mo deling is an appr oach f or the simula tion of unst eady turbulen t flo ws, and c an b e applied in c ombina tion with most -based UR ANS turbulenc e mo dels .To apply it in c om- bina tion with the SST - turbulenc e mo del, you c an simply selec t Scale-A daptiv e Simula tion (SAS) from the Model list in the Visc ous M odel dialo g box. Figur e 12.19: Scale-A daptiv e Simula tion (SAS) in C ombina tion with the SST Turbulenc e M odel You c an also apply SAS in c ombina tion with the f ollowing -based UR ANS mo dels: the S tandar d - model, the BSL - mo del, the Transition SST mo del, and the -based R eynolds str ess mo dels (RSM). Simply selec t the appr opriate Model and then enable the Scale-A daptiv e Simula tion (SAS) option in the Scale-Resolving S imula tion Options group b ox. For an e xample , see Figur e 12.20: Scale-A daptiv e Simula tion (SAS) in C ombina tion with the Transition SST M odel (p.1419 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1418Modeling Turbulenc eFigur e 12.20: Scale-A daptiv e Simula tion (SAS) in C ombina tion with the Transition SST M odel Note tha t for SAS mo deling , the Bounded C entral D ifferencing scheme (a vailable in the Solution Metho ds task page) is r ecommended f or momen tum discr etiza tion, and is the default setting . 1419Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p Sc ale-A daptiv e Simula tion (SAS) M odeling12.12. Setting U p the D etached E ddy Simula tion M odel When using the D etached E ddy Simula tion (DES) mo del, the f ollowing under lying R ANS turbulenc e models c an b e used: •Spalar t-Allmar as •Realizable - •SST - •BSL - •Transition SST Note tha t for the DES mo del, the Bounded C entral D ifferencing scheme (a vailable in the Solution Metho ds task page) is r ecommended f or momen tum discr etiza tion, and is the default setting . For additional inf ormation, see the f ollowing sec tions: 12.12.1. Setting U p DES with the S palar t-Allmar as M odel 12.12.2. Setting U p DES with the R ealizable k- ε Model 12.12.3. Setting U p DES with the SST k- ω Model 12.12.4. Setting U p DES with the BSL k- ω Model 12.12.5. Setting U p DES with the Transition SST M odel 12.12.1. Setting U p DES with the S palar t-Allmar as M odel To set up a D etached E ddy Simula tion with the S palar t-Allmar as mo del, selec t Detached E ddy Simu- lation (DES) from the Model list in the Visc ous M odel dialo g box and then selec t Spalar t-Allmar as from the RANS M odel list. ANSY S Fluen t uses Equa tion 4.244 (in the Theor y Guide ) to comput e the v alue of the length sc ale for the S palar t-Allmar as mo del. By default , the empir ical constan t is set t o 0.65. You c an change its v alue in the Cdes field under Model C onstan ts.The f ollowing options ar e available f or this mo del: •vorticit y-based pr oduc tion ( Vorticit y- and S train/V orticit y-Based P roduc tion (p.1439 )) •strain/v orticit y-based pr oduc tion ( Vorticit y- and S train/V orticit y-Based P roduc tion (p.1439 )) •dela yed DES ( Delayed D etached E ddy Simula tion (DDES) (p.1440 )) •viscous hea ting (alw ays enabled f or the densit y-based solv ers) ( Including the Viscous H eating E ffects (p.1437 )) •inclusion of cur vature correction ( Including the C urvature Correction f or the S palar t-Allmar as and Two- Equa tion Turbulenc e Models (p.1437 )) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1420Modeling Turbulenc eFigur e 12.21: The Visc ous M odel D ialo g Box Displa ying Options f or DES with the S palar t-Allmar as Model Additionally , you c an p erform the f ollowing DES-sp ecific func tion b y using the /define/models/vis- cous/detached-eddy-simulation? text command: •Modify only the length sc ales tha t app ear in the destr uction t erm in equa tion (the default is t o mo dify all length sc ales within the equa tion) 1421Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the D etached E ddy Simula tion M odel12.12.2. Setting U p DES with the Realizable k- ε Model To set up a D etached E ddy Simula tion with the R ealizable - mo del, selec t Detached E ddy Simula tion (DES) from the Model list in the Visc ous M odel dialo g box and then selec t Realizable k-epsilon from the RANS M odel list. The mo del-sp ecific options f or DES with the R ealizable - mo del ar e the f ollowing: •dela yed DES ( Delayed D etached E ddy Simula tion (DDES) (p.1440 )) •viscous hea ting (alw ays enabled f or the densit y-based solv ers) ( Including the Viscous H eating E ffects (p.1437 )) •inclusion of c ompr essibilit y eff ects (Including the C ompr essibilit y Effects Option (p.1438 )) The mo del c onstan t is set t o 0.61 f or the R ealizable - mo del (see DES with the R ealizable k- ε Model in the Theor y Guide ).The enhanc ed w all tr eatmen t (EWT- ) is alw ays enabled f or DES with the Realizable - mo del (see Enhanc ed Wall Treatmen t ε-Equa tion (E WT-ε) in the Theor y Guide ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1422Modeling Turbulenc eFigur e 12.22: The Visc ous M odel D ialo g Box Displa ying Options f or DES with the Realizable k-ε Model 12.12.3. Setting U p DES with the SST k- ω Model To set up a D etached E ddy Simula tion with the SST - mo del, selec t Detached E ddy Simula tion (DES) from the Model list in the Visc ous M odel dialo g box and then selec t SST k-omega from the RANS M odel list. The mo del-sp ecific options tha t you c an selec t for DES with the SST - mo del ar e the f ollowing: •low-R e corrections - option ( Low-R e Corrections (p.1440 )) •dela yed DES ( Delayed D etached E ddy Simula tion (DDES) (p.1440 )) •viscous hea ting (alw ays enabled f or the densit y-based solv ers) ( Including the Viscous H eating E ffects (p.1437 )) 1423Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the D etached E ddy Simula tion M odel•inclusion of cur vature correction ( Including the C urvature Correction f or the S palar t-Allmar as and Two- Equa tion Turbulenc e Models (p.1437 )) •inclusion of pr oduc tion limit ers ( Including P roduc tion Limit ers f or Two-Equa tion M odels (p.1438 )) •inclusion of the In termitt ency Transition mo del •Shielding func tions—F1, F2, DDES (D elayed DES) and IDDES (Impr oved D elayed DES)—ar e available when the dela yed DES option is enabled ( Shielding F unctions f or the BSL / SST / Transition SST D etached E ddy Simula tion M odel (p.1448 )) The mo del c onstan t is set t o 0.61 f or the SST - RANS mo del (see DES with the BSL or SST k- ω Model in the Theor y Guide ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1424Modeling Turbulenc eFigur e 12.23: The Visc ous M odel D ialo g Box Displa ying Options f or DES with the SST k- ω Model 12.12.4. Setting U p DES with the BSL k- ω Model To set up a D etached E ddy Simula tion with the BSL - mo del f or a tr ansien t case, selec t k-omega from the Model list in the Visc ous M odel dialo g box, selec t BSL from the k-omega M odel list, and enable the Detached E ddy Simula tion (DES) option in the Scale-Resolving S imula tion Options group b ox. The mo del-sp ecific options tha t you c an selec t for DES with the BSL - mo del ar e the f ollowing: 1425Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the D etached E ddy Simula tion M odel•low-R e corrections - option ( Low-R e Corrections (p.1440 )) •dela yed DES ( Delayed D etached E ddy Simula tion (DDES) (p.1440 )) •viscous hea ting (alw ays enabled f or the densit y-based solv ers) ( Including the Viscous H eating E ffects (p.1437 )) •inclusion of cur vature correction ( Including the C urvature Correction f or the S palar t-Allmar as and Two- Equa tion Turbulenc e Models (p.1437 )) •inclusion of c ompr essibilit y eff ects (Including the C ompr essibilit y Effects Option (p.1438 )) •inclusion of pr oduc tion limit ers ( Including P roduc tion Limit ers f or Two-Equa tion M odels (p.1438 )) •inclusion of the In termitt ency Transition mo del •Shielding func tions—F1, F2, DDES (D elayed DES) and IDDES (Impr oved D elayed DES)—ar e available when the dela yed DES option is enabled ( Shielding F unctions f or the BSL / SST / Transition SST D etached E ddy Simula tion M odel (p.1448 )) The mo del c onstan t is set t o 0.61 f or the BSL - RANS mo del (see DES with the BSL or SST k- ω Model in the Theor y Guide ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1426Modeling Turbulenc eFigur e 12.24: The Visc ous M odel D ialo g Box Displa ying Options f or DES with the BSL k- ω Model 12.12.5. Setting U p DES with the Transition SST M odel To set up a D etached E ddy Simula tion with the Transition SST mo del f or a tr ansien t case, selec t Transition SST from the Model list in the Visc ous M odel dialo g box and then enable the Detached Eddy Simula tion (DES) option in the Scale-Resolving S imula tion Options group b ox. 1427Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the D etached E ddy Simula tion M odelFor DES with the Transition SST mo del, you c an cho ose t o enable the Delayed DES option in the DES Options group b ox (see Delayed D etached E ddy Simula tion (DDES) (p.1440 ) for details). When this option is enabled y ou c an mak e a selec tion fr om the Shielding F unc tions list, as descr ibed in Shielding Functions f or the BSL / SST / Transition SST D etached E ddy Simula tion M odel (p.1448 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1428Modeling Turbulenc eFigur e 12.25: The Visc ous M odel D ialo g Box Displa ying Options f or DES with the Transition SST Model 1429Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the D etached E ddy Simula tion M odelRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1430Modeling Turbulenc e12.13. Setting U p the L arge E ddy Simula tion M odel If you cho ose the LES mo del, the f ollowing sub grid-sc ale submo dels ar e available ( Sub grid-Sc ale M od- el (p.1443 )): •Smagor insk y-Lilly •WALE •WMLES •WMLES S-Omega •Kinetic-E nergy Transp ort The default Subgrid-Sc ale M odel for the LES mo del is the WALE mo del. Figur e 12.26: The Visc ous M odel D ialo g Box Displa ying the L arge E ddy Simula tion M odel Options The LES options tha t are available f or the Smagor insk y-Lilly submo del ar e 1431Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the Lar ge E ddy Simula tion M odel•Dynamic S tress •Dynamic E nergy Flux (available only when the Dynamic S tress option is enabled) •Dynamic Sc alar F lux (available only when the Dynamic S tress option is enabled) The LES options tha t are available when the Kinetic-E nergy Transp ort submo del is selec ted ar e Dy- namic E nergy Flux and Dynamic Sc alar F lux. The Dynamic Fv ar option is a vailable f or all of the sub grid-sc ale submo dels when Non-P remix ed Combustion or Partially P remix ed C ombustion is selec ted in the Species M odel D ialog Box (p.3294 ). This option enables the d ynamic mix ture fraction v arianc e mo del. See The N on-P remix ed M odel f or LES in the Theor y Guide for details . When using the LES mo del, you c an enable the Werner-W engle near-w all tr eatmen t thr ough the f ollowing text command:define/models/viscous/near-wall-treatment/werner-wengle-wall- fn? . See LES N ear-W all Treatmen t in the Theor y Guide for details . 12.14. Model C onstan ts It is also p ossible t o mo dify the Model C onstan ts, but this is not nec essar y for most applic ations . For mor e inf ormation ab out the c onstan ts, see Spalar t-Allmar as M odel through Large E ddy Simula tion (LES) Model (in the Theor y Guide ). Note tha t C1-PS and C2-PS are the c onstan ts and in the linear pressur e-str ain appr oxima tion of Equa tion 4.204 and Equa tion 4.205 (in the Theor y Guide ), and C1’-PS and C2’-PS are the c onstan ts and in Equa tion 4.206 (in the Theor y Guide ).C1-SSG-PS ,C1’-SSG- PS,C2-SSG-PS ,C3-SSG-PS ,C3’-SSG-PS ,C4-SSG-PS , and C5-SSG-PS are the c onstan ts , , , , , , and in the quadr atic pr essur e-str ain appr oxima tion of Equa tion 4.215 (in the Theor y Guide ). 12.15. Setting U p the E mbedded L arge E ddy Simula tion (ELES) M odel As descr ibed in Emb edded Lar ge E ddy Simula tion (ELES) in the Theor y Guide , the Emb edded Lar ge Eddy Simula tion mo del is used when mo deling a smaller emb edded LES z one within a lar ger R ANS computa tional domain. Recall tha t the in terface between the upstr eam R ANS z one and the LES z one must b e defined (b y assigning the in terface to a v elocity fluc tuation algor ithm). In addition, the in terface between the LES z one and the do wnstr eam R ANS z one must b e consider ed. This sec tion descr ibes ho w to set up the Emb edded Lar ge E ddy Simula tion mo del. 1.In the Visc ous M odel dialo g box, enable an y RANS mo del (f or e xample , - , - ), or y ou c an selec t DES, SAS, SDES, or SBES. The only R ANS mo del not c ompa tible with ELES is the S palar t-Allmar as model, as a one-equa tion mo del c annot pr ovide the r equir ed turbulen t length sc ale t o the in terface metho d. If a R ANS mo del is selec ted, the mo del is applied globally t o the c omputa tional domain, however, values f or turbulenc e variables ar e frozen within the ELES r egion. The fr ozen sta te of the ELES zone is used t o det ermine the flo w conditions (f or - , - , and so on) a t the do wnstr eam LES- RANS z one in terface. Note tha t this appr oach r equir es a fair ly w ell c onverged global R ANS solution t o star t with. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1432Modeling Turbulenc eIf DES, SAS, SDES, or SBES is used in the out er zone , these mo dels ar e not fr ozen, but r un in the back ground in the ELES r egion, obtaining pr oper flo w conditions (f or - , - , etc.) at the downstr eam LES-R ANS z one in terface. 2.For the sp ecified fluid c ell z one , enable LES Z one in the Fluid dialo g box (Figur e 12.27: Specifying an ELES Z one in the F luid D ialog Box (p.1434 )).This enables the Embedded LES tab in the Fluid dialo g box. Note When DES, SAS, SDES, or SBES is used f or the global mo del, this and the ne xt step can, but need not , be sk ipped. (Rememb er the gener al limita tions of DES in fr ee, wall-indep enden t flo ws.) If you cho ose t o sk ip these st eps, then pr oceed with st ep 4. The ELES Z one option will only app ear in the Fluid dialo g box if y ou selec t the Transien t Solver.This must b e done manually f or R ANS mo dels . 3.In the Embedded LES tab , you c an then sp ecify the Embedded S ubgrid-Sc ale M odel, and the Mo- men tum S patial D iscr etiza tion . For the Embedded S ubgrid-Sc ale M odel, the f ollowing sub grid-sc ale submo dels ar e available (Sub grid-Sc ale M odel (p.1443 )): •Smagor insk y-Lilly •WALE •Dynamic S magor insk y (which is the same as the LES mo del with Smagor insk y-Lilly selec ted and the Dynamic S tress option enabled) •WMLES •WMLES S-Omega The default Embedded-S ubgrid Sc ale M odel for the ELES mo del is the WALE mo del. When the WALE mo del is selec ted, you c an sp ecify a v alue f or Cwale to define (see Wall- Adapting L ocal Eddy-Viscosity (WALE) M odel in the Theor y Guide for details). Likewise , when the S magor insk y-Lilly mo del is selec ted, you c an sp ecify a v alue f or Cs to define (see Smagor insk y-Lilly M odel in the Theor y Guide for details). For the Momen tum S patial D iscr etiza tion , the f ollowing options ar e available: •Bounded C entral D ifferencing •Central D ifferencing 1433Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the Emb edded Lar ge E ddy Simula tion (ELES) M odelFigur e 12.27: Specifying an ELES Z one in the F luid D ialo g Box 4.Selec t an appr opriate interior in terface and designa te it as the R ANS-LES in terface, by right-click ing the b oundar y zone name in the tr ee (under Setup/B oundar y Conditions ) and selec ting rans-les-in- terface in the Type sub-menu . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1434Modeling Turbulenc eFigur e 12.28: Specifying the R ANS/LES In terface The RANS/LES In terface dialo g box (Figur e 12.29: The R ANS/LES In terface Dialog Box (p.1436 )) will op en, allo wing y ou t o assign a Zone N ame , as w ell as the Fluctuating Velocity Algor ithm and the Numb er O f Vortices.The options f or the Fluctuating Velocity Algor ithm are: •No Perturba tions •Spectral S ynthesiz er •Vortex M etho d For mor e inf ormation ab out these options , refer to Inlet B oundar y Conditions f or Sc ale R esolving Simula tions in the Theor y Guide . Note tha t the Numb er O f Vortices is the amoun t of v ortices tha t the selec ted metho d distr ibut es randomly o ver the fac e zone and uses t o gener ate turbulen t fluc tuations .The v alue should b e 1435Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the Emb edded Lar ge E ddy Simula tion (ELES) M odellarge enough t o mak e sur e ther e ar e no sp ots on the fac e zone tha t are unaff ected b y an y vortex. Large numb ers ma y sligh tly incr ease the CPU eff ort, but will not impair the r esults . Note The minimum ad vised numb er of v ortices is appr oxima tely a quar ter of the numb er of c ell fac es a t the LES side of the in terface. Figur e 12.29: The R ANS/LES In terface D ialo g Box If the R ANS/LES in terface is a non-c onformal mesh in terface, you c an find the name of the in- terface in terior z one tha t you w ant to change in to a rans-les-in terface zone b y using the List butt on in the Mesh In terfaces D ialog Box (p.3852 ). Imp ortant It is r ecommended tha t the R ANS-LES in terface be situa ted in a r egion wher e ther e is no backflo w. 12.16. Setup Options f or A ll Turbulenc e M odeling For mor e inf ormation ab out the v arious options a vailable f or the turbulenc e mo dels , see Spalar t-Allmar as Model through Large E ddy Simula tion (LES) M odel (in the Theor y Guide ). Instr uctions f or ac tivating these options ar e pr ovided her e. For additional inf ormation, see the f ollowing sec tions: 12.16.1. Including the Viscous H eating E ffects 12.16.2. Including Turbulenc e Gener ation D ue to Buoyancy 12.16.3. Including the C urvature Correction f or the S palar t-Allmar as and Two-Equa tion Turbulenc e Models 12.16.4. Including the C ompr essibilit y Effects Option 12.16.5. Including P roduction Limit ers f or Two-Equa tion M odels 12.16.6. Including the In termitt ency Transition M odel 12.16.7. Vorticity- and S train/V orticity-Based P roduction 12.16.8. Delayed D etached E ddy Simula tion (DDES) 12.16.9. Differential Viscosity Modific ation 12.16.10. Swirl Modific ation 12.16.11. Low-Re Corrections 12.16.12. Shear F low Corrections Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1436Modeling Turbulenc e12.16.13. Turbulenc e Damping 12.16.14. Including P ressur e Gradien t Effects 12.16.15. Including Thermal E ffects 12.16.16. Including the Wall R eflec tion Term 12.16.17. Solving the k E qua tion t o Obtain Wall B oundar y Conditions 12.16.18. Quadr atic P ressur e-Strain M odel 12.16.19. Stress-Omega and S tress-BSL M odels 12.16.20. Sub grid-Sc ale M odel 12.16.21. Customizing the Turbulen t Viscosity 12.16.22. Customizing the Turbulen t Prandtl and Schmidt N umb ers 12.16.23. Modeling Turbulenc e with N on-N ewtonian F luids 12.16.24. Including Sc ale-A daptiv e Simula tion with ω-Based UR ANS M odels 12.16.25. Including D etached E ddy Simula tion with the Transition SST M odel 12.16.26. Including the SDES or SBES M odel with BSL, SST , and Transition SST M odels 12.16.27. Shielding F unctions f or the BSL / SST / Transition SST D etached E ddy Simula tion M odel 12.16.1. Including the Visc ous H eating E ffects For inf ormation ab out including visc ous hea ting eff ects in y our mo del, see Inclusion of the Viscous Dissipa tion Terms in the Theor y Guide and Solving H eat Transf er P roblems (p.1467 ). 12.16.2. Including Turbulenc e Gener ation D ue t o Buo yanc y If you sp ecify a nonz ero gr avity force (in the Operating C onditions D ialog Box (p.3470 )), and y ou ar e modeling a non-isother mal flo w, the gener ation of turbulen t kinetic ener gy due t o buo yancy ( in Equa tion 4.39 ) is, by default , alw ays included in the equa tion. However, ANSY S Fluen t do es not , by default , include the buo yancy eff ects on . To include the buo yancy eff ects on , you must tur n on the Full Buo yanc y Effects option under Options in the Viscous M odel D ialog Box (p.3253 ). This option is a vailable f or all thr ee - mo dels and f or the -based RSM (tha t is, with the Linear Pressur e-Strain or Quadr atic P ressur e-Strain mo del selec ted). 12.16.3. Including the C urvature Correction f or the S palar t-Allmar as and Two-Equa tion Turbulenc e M odels Eddy-visc osity mo dels displa y an insensitivit y to str eamline cur vature and sy stem r otation, which pla y a signific ant role in man y turbulen t flo ws of pr actical in terest, as descr ibed in Curvature Correction f or the S palar t-Allmar as and Two-Equa tion M odels in the Theor y Guide . A mo dific ation t o the turbulenc e produc tion t erm is a vailable t o sensitiz e the f ollowing standar d edd y-visc osity mo dels t o the eff ects of str eamline cur vature and sy stem r otation: •Spalar t-Allmar as one-equa tion mo del •Standar d, RNG, and R ealizable ( - ) mo dels •Standar d ( - ), BSL, SST , and Transition SST •Scale-A daptiv e Simula tion (SAS) 1437Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setup Options f or A ll Turbulenc e Modeling•Detached E ddy Simula tion with BSL (DES-BSL), with SST (DES-SST ), with S palar t-Allmar as (DES-SA), and with R ealizable ( - ) mo del (DES-r ke). •Shielded D etached E ddy Simula tion (SDES) •Stress-B lended E ddy Simula tion (SBES) Note tha t both the RNG and R ealizable ( - ) turbulenc e mo dels alr eady ha ve their o wn t erms t o include rotational or swir l eff ects (see RNG S wirl Modific ation and Modeling the Turbulen t Viscosity in the Theor y Guide for mor e inf ormation). The cur vature correction option should ther efore be used with caution f or these t wo mo dels and is off ered mainly f or c omplet eness f or RNG and R ealizable ( - ). Enable the Curvature Correction option under Options in the Viscous M odel D ialog Box (p.3253 ). You c an sp ecify a v alue f or CCUR V under Curvature Correction Options to influenc e the str ength of the cur vature correction if needed f or a sp ecific flo w.You ha ve the option of sp ecifying a c onstan t or via a UDF . 12.16.4. Including the C ompr essibilit y Effects Option The Compr essibilit y Effects option is a vailable under Options in the Viscous M odel D ialog Box (p.3253 ) for most -based mo dels , -based mo dels , and R eynolds str ess mo dels when the c ompr essible f orm of the ideal gas la w or the r eal-gas mo del is enabled .This option c an impr ove the pr edic tion of fr ee shear la yers a t high M ach numb ers. See Model Enhanc emen ts (p.1383 ) for recommenda tions on when to use this option. For details ab out ho w this c orrection is implemen ted, see Effects of C ompr essibilit y on Turbulenc e in the k- ε Models and Compr essibilit y Effects in the Theor y Guide . 12.16.5. Including P roduc tion Limit ers f or Two-Equa tion M odels A disad vantage of standar d two-equa tion turbulenc e mo dels is the e xcessiv e gener ation of the turbu- lenc e ener gy, , in the vicinit y of stagna tion p oints. In or der t o avoid the buildup of turbulen t kinetic ener gy in the stagna tion r egions , two formula tions ar e available in or der t o limit the pr oduc tion t erm in the turbulenc e kinetic ener gy equa tions: •Produc tion Limit er (f or details , see Equa tion 4.382 in the Fluent Theor y Guide ) •Produc tion K ato-Launder (f or details , see Equa tion 4.386 in the Fluent Theor y Guide ) Both these f ormula tions c an b e acc essed under Options in the Visc ous M odel dialo g box.The Pro- duc tion Limit er mo del c oefficien t is c alled the Produc tion Limit er C lip F actor and has a default value of 10. This v alue c an b e mo dified under Model C onstan ts onc e the Produc tion Limit er formu- lation is enabled . You c an use the f ollowing t ext commands t o set the f ormula tions: •Produc tion Limit er /define/models/viscous/turbulence-expert/production-limiter?[yes] •Produc tion K ato-Launder /define/models/viscous/turbulence-expert/kato-launder-model?[yes] The Produc tion Limit er is a vailable f or the f ollowing turbulenc e mo dels: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1438Modeling Turbulenc e•Standar d, RNG, and R ealizable ( - ) mo dels •Standar d ( - ), BSL, SST , and Transition SST •Scale-A daptiv e Simula tion (SAS) •Detached E ddy Simula tion with BSL (DES-BSL), with SST (DES-SST ), and with R ealizable ( - ) mo dels (DES- rke) •Shielded D etached E ddy Simula tion (SDES) •Stress-B lended E ddy Simula tion (SBES) By default , this limit er is enabled f or all turbulenc e mo dels based on the equa tion. The Produc tion K ato-Launder formula tion f or the pr oduc tion t erm is a vailable f or the f ollowing tur- bulenc e mo dels: •Standar d, and RNG ( - ) mo dels •Standar d ( - ), BSL, SST , and Transition SST •Scale-A daptiv e Simula tion (SAS) •Detached E ddy Simula tion with BSL (DES-BSL) and with SST (DES-SST ) •Shielded D etached E ddy Simula tion (SDES) •Stress-B lended E ddy Simula tion (SBES) The K ato-Launder f ormula tion is enabled b y default f or the Transition SST mo del only . 12.16.6. Including the In termitt enc y Transition M odel The In termitt ency Transition mo del is a vailable f or the BSL - mo del, SST - mo del, Scale-A daptiv e Simula tion with BSL / SST , Detached-E ddy Simula tion with BSL / SST , Shielded D etached E ddy Simula tion (SDES) with BSL / SST , and S tress-B lended E ddy Simula tion (SBES) with BSL / SST . It can b e included by enabling Intermitt enc y Transition M odel in the Options group b ox in the Visc ous M odel dialo g box with the appr opriate turbulenc e mo del selec ted. When the Intermitt enc y Transition M odel option is enabled , the additional option Include C rossflo w Transition is a vailable . It allo ws you t o include the eff ects of cr ossflo w instabilit y. For details ab out the In termitt ency Transition mo del, see Intermitt ency Transition M odel in the Theor y Guide . 12.16.7. Vorticit y- and S train/V orticit y-Based P roduc tion For the S palar t-Allmar as mo del, you c an cho ose either Vorticit y-Based P roduc tion or Strain/V orticit y- Based P roduc tion under Spalar t-Allmar as P roduc tion in the Viscous M odel D ialog Box (p.3253 ). If you cho ose Vorticit y-Based P roduc tion , ANSY S Fluen t will c omput e the v alue of the def ormation tensor using Equa tion 4.22 (in the Theor y Guide ); if y ou cho ose Strain/V orticit y-Based P roduc tion , it uses Equa tion 4.24 (in the Theor y Guide ). 1439Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setup Options f or A ll Turbulenc e Modeling(These options will not app ear unless y ou ha ve enabled the S palar t-Allmar as mo del.) 12.16.8. Delayed D etached E ddy Simula tion (DDES) The Delayed DES option is r ecommended when using the DES mo del. This option pr eser ves the R ANS model thr oughout the b oundar y layer. For mor e inf ormation, see Detached E ddy Simula tion (DES) in the Theor y Guide . 12.16.9. Differential Visc osit y M odific ation The RNG turbulenc e mo del in ANSY S Fluen t has an option of using a diff erential f ormula f or the eff ective viscosity (Equa tion 4.44 in the Theor y Guide ) to acc oun t for the lo w-R eynolds-numb er eff ects.To enable this option, the Differential Visc osit y M odel option under RNG Options in the Viscous M odel Dialog Box (p.3253 ) must b e enabled . Imp ortant This option app ears when y ou ha ve enabled the RNG - mo del. 12.16.10. Swirl Modific ation After y ou ha ve chosen the RNG mo del, the swir l mo dific ation tak es eff ect, by default , for all thr ee-di- mensional flo ws and axisymmetr ic flo ws with swir l.The default swir l constan t ( in Equa tion 4.46 in the Theor y Guide ) is set t o 0.07, which w orks w ell for w eakly to mo derately swir ling flo ws. However, for str ongly swir ling flo ws, you ma y need t o use a lar ger swir l constan t. To change the v alue of the swir l constan t, you must first enable the Swirl Domina ted F low option under RNG Options in the Viscous M odel D ialog Box (p.3253 ). Imp ortant This option will not app ear unless y ou ha ve enabled the RNG - mo del. 12.16.11. Low-Re C orrections If an y of the - mo dels or the S tress-Omega RSM is used , you ma y enable a lo w-R eynolds-numb er correction t o the turbulen t visc osity by enabling the Low-Re C orrections option under k-omega Options in the Visc ous M odel dialo g box. By default , this option is not enabled , and the damping coefficien t ( in Equa tion 4.74 in the Theor y Guide ) is equal t o 1. 12.16.12. Shear F low C orrections In the standar d - mo del and the S tress-Omega RSM, you also ha ve the option of including c orrections to impr ove the accur acy in pr edic ting fr ee shear flo ws.The Shear F low C orrections option under the k-omega Options is enabled b y default in the Visc ous M odel dialo g box, as these c orrections ar e included in the standar d - mo del [145] (p.4013 ).When this option is enabled , ANSY S Fluen t will calcula te using Equa tion 4.84 (in the Theor y Guide ) and using Equa tion 4.91 (in the Theor y Guide ). If this option is disabled , and will b e set equal t o 1. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1440Modeling Turbulenc e12.16.13. Turbulenc e Damping For c ases tha t use the VOF or M ixture multiphase mo dels , or the E uler ian multiphase mo del with the Multi-F luid VOF option selec ted, you c an enable Turbulenc e D amping (in the k-omega Options group box).This option is r equir ed f or b etter resolution of v elocity gr adien ts in the vicinit y of fluid-fluid in- terface. After enabling Turbulenc e D amping , you c an sp ecify the Damping F actor, which b y default is set t o 10. For a theor etical discussion ab out turbulenc e damping , refer to Turbulenc e Damping in the Fluent Theor y Guide . Note Incorporation of turbulenc e damping is r ecommended only f or shar p and shar p/disp ersed interface mo deling t ypes. 12.16.14. Including P ressur e Gradien t Effects If the enhanc ed w all tr eatmen t is used , you ma y include the eff ects of pr essur e gr adien ts b y enabling the Pressur e Gradien t Effects option under the Enhanc ed Wall Treatmen t Options .When this option is enabled , ANSY S Fluen t will include the c oefficien t in Equa tion 4.348 (in the Theor y Guide ). 12.16.15. Including Thermal E ffects If the enhanc ed w all tr eatmen t is used , you ma y include ther mal eff ects b y enabling the Thermal E ffects option under Enhanc ed Wall Treatmen t Options .When this option is enabled , ANSY S Fluen t will in- clude the c oefficien t in Equa tion 4.348 (in the Theor y Guide ). will also b e included in Equa tion 4.348 when the Thermal E ffects option is enabled if the ideal gas la w is selec ted f or the fluid densit y in the Create/Edit M aterials dialo g box. 12.16.16. Including the Wall Reflec tion Term If the RSM is used with the default mo del f or linear pr essur e-str ain, ANSY S Fluen t will, by default , include the w all-r eflec tion eff ects in the pr essur e-str ain t erm.That is, ANSY S Fluen t will c alcula te using Equa tion 4.206 (in the Theor y Guide ) and include it in Equa tion 4.203 (in the Theor y Guide ). For the quadr atic pr essur e-str ain mo del, Stress-Omega mo del, and S tress-BSL mo del, the w all-r eflec tion eff ects are not r equir ed and ar e not included . Imp ortant The empir ical constan ts and the func tion used in the c alcula tion of are calibr ated for simple c anonic al flo ws such as channel flo ws and fla t-pla te boundar y layers in volving a single w all. If the flo w in volves multiple w alls and the w all has signific ant cur vature (for example , an axisymmetr ic pip e or cur vilinear duc t), the inclusion of the w all-r eflec tion t erm in Equa tion 4.206 (in the Theor y Guide ) ma y not impr ove the accur acy of the RSM pr edic tions . In such c ases , you c an disable the w all-r eflec tion eff ects b y tur ning off the Wall Reflec tion Effects under Reynolds-S tress Options in the Viscous M odel D ialog Box (p.3253 ). 1441Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setup Options f or A ll Turbulenc e Modeling12.16.17. Solving the k E qua tion t o Obtain Wall B oundar y Conditions For the -based R eynolds str ess mo dels , by default ANSY S Fluen t uses the e xplicit setting of b oundar y conditions f or the R eynolds str esses near the w alls, with the v alues c omput ed with Equa tion 4.233 (in the Theor y Guide ).The turbulen t kinetic ener gy, , is c alcula ted b y solving the equa tion obtained by summing Equa tion 4.199 (in the Theor y Guide ) for nor mal str esses .To disable this option and use the w all b oundar y conditions giv en in Equa tion 4.234 (in the Theor y Guide ), turn off the Wall BC fr om k Equa tion under the Reynolds-S tress Options in the Visc ous M odel dialo g box. Imp ortant This option will not app ear unless y ou ha ve enabled the Reynolds S tress mo del. 12.16.18. Quadr atic P ressur e-Strain M odel To use the quadr atic pr essur e-str ain mo del descr ibed in Quadr atic P ressur e-Strain M odel (in the Theor y Guide ), enable the Quadr atic P ressur e-Strain M odel option under Reynolds-S tress Options in the Viscous M odel D ialog Box (p.3253 ). (This option will not app ear unless y ou ha ve enabled the RSM.) The following options ar e not a vailable when the Quadr atic P ressur e-Strain M odel is enabled: •Wall Reflec tion E ffects under Reynolds-S tress Options •Enhanc ed Wall Treatmen t under Near-W all Treatmen t 12.16.19. Stress-Omega and S tress-BSL M odels To use the S tress-Omega mo del (descr ibed in Stress-Omega M odel) or the S tress-BSL mo del (descr ibed in Stress-BSL M odel), selec t Stress-Omega or Stress-BSL , respectively, from the Reynolds-S tress Model list in the Viscous M odel D ialog Box (p.3253 ). (These options will not app ear unless y ou ha ve enabled the RSM.) The f ollowing options ar e not a vailable when the Stress-Omega or the Stress-BSL model is selec ted: •Wall BC fr om k E qua tion under Reynolds-S tress Options •Wall Reflec tion E ffects under Reynolds-S tress Options •Standar d Wall F unc tions under Near-W all Treatmen t •Scalable Wall F unc tions under Near-W all Treatmen t •Non-E quilibr ium Wall F unc tions under Near-W all Treatmen t •Enhanc ed Wall Treatmen t under Near-W all Treatmen t Instead, the f ollowing options ar e available: •Low-Re C orrections under k-omega Options (for Stress-Omega only) •Shear F low C orrections under k-omega Options (for Stress-Omega only) •Scale-A daptiv e Simula tion (SAS) under Scale-Resolving S imula tion Options Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1442Modeling Turbulenc e12.16.20. Subgrid-Sc ale M odel If you ha ve selec ted the Large E ddy Simula tion mo del, you will b e able t o cho ose one of the sub grid- scale mo dels descr ibed in Sub grid-Sc ale M odels (in the Theor y Guide ).You c an cho ose fr om the Smagor insk y-Lilly ,WALE ,WMLES ,WMLES S-Omega , or Kinetic-E nergy Transp ort sub grid-sc ale models . Note tha t Dynamic S tress is an option a vailable with the Smagor insk y-Lilly mo del (and when it is enabled , this mo del is r eferred t o as the “dynamic S magor insk y” mo del), while the Kinetic-E nergy Transp ort mo del is alw ays run as a d ynamic mo del. The Dynamic Fv ar option is a vailable f or all of the sub grid-sc ale mo dels when Non-P remix ed C ombustion or Partially P remix ed C ombustion is selec ted in the Species M odel D ialog Box (p.3294 ). Imp ortant These options will not app ear unless y ou ha ve enabled the LES mo del. 12.16.21. Customizing the Turbulen t Visc osit y If you ar e using the S palar t-Allmar as, - , - , DES, or LES mo dels , a UDF c an b e used t o cust omiz e the turbulen t visc osity.This option will enable y ou t o mo dify in the c ase of the S palar t-Allmar as, - , and - mo dels , and inc orporate complet ely new sub grid mo dels in the c ase of the LES mo del. SBES with BSL / SST allo ws the usage of a UDF in or der t o pr ovide a cust om f ormula tion f or in the RANS r egion, but not f or the sub grid mo del in the LES r egion. More inf ormation ab out UDFs c an b e found in the Fluen t Customiza tion M anual . In the Viscous M odel D ialog Box (p.3253 ), under User-D efined F unc tions , selec t the appr opriate user- defined func tion in the Turbulen t Visc osit y drop-do wn list. For the LES mo del, selec t the appr opriate UDF in the Subgrid-Sc ale Turbulen t Visc osit y drop-do wn list. 12.16.22. Customizing the Turbulen t Prandtl and Schmidt N umb ers You c an use UDFs t o cust omiz e the turbulen t Prandtl and Schmidt numb ers. For the standar d and realizable - mo dels and the standar d - mo del, your UDF c an c alcula te the TKE P randtl numb er ( ) and either the TDR or SDR P randtl numb er ( or ), dep ending on whether y ou ar e using the - or - mo del. All turbulenc e mo dels allo w you t o use UDFs f or the turbulen t Prandtl numb er a t the w all ( in Equa tion 4.319 in the Theor y Guide ), and all turbulen t mo dels e xcept f or the RNG - model allo w you t o use UDFs f or the turbulen t Prandtl numb er for ener gy ( in, for e xample ,Equa- tion 4.63 or Equa tion 4.224 in the Theor y Guide ), as w ell as the turbulen t Schmidt numb er ( , in Equa tion 7.3 in the Theor y Guide ) if sp ecies tr ansp ort has b een enabled . Note tha t UDFs c annot b e used f or the turbulen t Prandtl numb er for ener gy or the turbulen t Schmidt numb er if y ou ha ve enabled Dynamic E nergy Flux or Dynamic Sc alar F lux, respectively, as par t of the LES mo del. More inf ormation about UDFs c an b e found in the Fluen t Customiza tion M anual . In the Viscous M odel D ialog Box (p.3253 ), under User-D efined F unc tions , selec t the appr opriate UDF from the dr op-do wn lists in the Prandtl N umb ers or Prandtl and Schmidt N umb ers group b ox.The options will dep end on the turbulenc e mo del y ou ha ve selec ted (as not ed pr eviously), and include: TKE P randtl N umb er,TDR P randtl N umb er,SDR P randtl N umb er,Energy Prandtl N umb er,Wall Prandtl N umb er, and Turbulen t Schmidt N umb er. Note tha t the a vailabilit y of these dr op-do wn lists can b e aff ected b y your settings f or the ener gy equa tion and the multiphase and c ombustion mo dels . 1443Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setup Options f or A ll Turbulenc e Modeling12.16.23. Modeling Turbulenc e with N on-N ewtonian F luids If the turbulen t flo w in volves non-N ewtonian fluids , you c an use the define/models/ viscous/tur- bulence-expert/turb-non-newtonian? text command t o enable the selec tion of non-N ewto- nian options f or the ma terial visc osity. See Viscosity for N on-N ewtonian F luids (p.1112 ) for details ab out these options . 12.16.24. Including Sc ale-A daptiv e Simula tion with ω-Based UR ANS M odels You ha ve the option of including Sc ale-A daptiv e Simula tion (SAS) with most -based UR ANS mo dels . For details ab out SAS and ho w to include it , see Scale-A daptiv e Simula tion (SAS) (p.1386 ) and Setting Up Sc ale-A daptiv e Simula tion (SAS) M odeling (p.1418 ), respectively. 12.16.25. Including D etached E ddy Simula tion with the Transition SST Model You ha ve the option of including D etached E ddy Simula tion (DES) with the Transition SST mo del. For details ab out DES and ho w to include it , see Detached E ddy Simula tion (DES) (p.1386 ) and Setting U p DES with the Transition SST M odel (p.1427 ), respectively. 12.16.26. Including the SDES or SBES M odel with BSL, SST , and Transition SST M odels To enable a h ybrid R ANS-LES mo del with an impr oved shielding func tion c ompar ed t o DDES / IDDES, you c an enable the Stress Blending (SBES) / S hielded DES option in the Scale-Resolving S imula tion Options group b ox of the Visc ous M odel dialo g box.This option is a vailable f or 3D tr ansien t cases when y ou ha ve selec ted one of the f ollowing mo dels (see Figur e 12.30: The Viscous M odel D ialog Box with the SBES Options (p.1446 )): •Gener alized - (GEK O) mo del •Baseline (BSL) - mo del •Shear-S tress Transp ort (SST ) - mo del •Transition SST mo del You c an then selec t one of the f ollowing fr om the Hybr id M odel list: •SDES to apply only a shielding func tion ( Shielded D etached E ddy Simula tion (SDES) in the Fluent Theor y Guide ) •SBES to apply a shielding func tion with str ess blending ( Stress-B lended E ddy Simula tion (SBES) in the Fluent Theor y Guide ) •SBES with U ser-D efined F unc tion to define y our o wn blending func tion z onally f or cases wher e the division between R ANS and LES is clear fr om the geometr y and the flo w ph ysics (DEFINE_SBES_BF in the Fluent Customization Manual ) If you selec t SBES or SBES with U ser-D efined F unc tion for the Hybr id M odel, you c an also selec t one of the f ollowing sub grid-sc ale (LES) mo dels: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1444Modeling Turbulenc e•Smagor insk y-Lilly mo del •Dynamic S magor insk y-Lilly mo del •Wall-A dapting L ocal Eddy-Viscosity (WALE ) mo del •Algebr aic Wall-M odeled LES - (WMLES S-Omega ) mo del The WALE mo del is r ecommended , as it pr ovides the lo west edd y visc osity in 2D flo w regions and ther eby allo ws the flo w to quick ly de velop 3D turbulenc e str uctures in separ ating shear la yers.The combina tion of SBES with the WMLES S-Omega formula tion is lik ely not a useful c ombina tion, as the SBES-W ALE mo del c ombina tion c an b y itself ac t in a WMLES mo de. If you selec t SBES or SBES with U ser-D efined F unc tion for the Hybr id M odel, you c an also sp ecify an in teger v alue (b etween 1 and 10) f or Update In terval k-omega , which det ermines ho w of ten the and equa tions ar e comput ed dur ing a r un. In man y cases , the global time st ep r equir ed f or the LES p ortion of the c alcula tion is unnec essar ily fine for the R ANS p ortion. For this r eason, it is not r equir ed tha t the - par t of the SBES mo del is up dated after e very time st ep. Reducing the fr equenc y at which the - equa tions ar e solv ed b y sp ecifying an update in terval can p ositiv ely impac t the solution time , with minimal impac t on the solution or c on- vergenc e. An optimal v alue f or the par amet er is 5. Note tha t the momen tum equa tions as w ell as the LES edd y-visc osity portion of the SBES mo del ar e up dated a t every time st ep.The par amet er only r educ es the numb er of up dates of the and equa tions , as w ell as tha t of the blending func tion. For e xample , if y ou sp ecify an up date in terval of 5, the solv er w ould up date the - portion e very 5th timest ep, while still up dating the LES edd y visc osity portion e very timest ep. Note The Update In terval k-omega func tionalit y has the f ollowing limita tions: •Not compa tible with multiphase flo w. •Not compa tible with adaptiv e time-st epping . •The time scheme f or the and equa tions ar e aut oma tically set t o first or der in c ases of v ariable densit y flo w or mo ving meshes .The time scheme f or other equa tions is not aff ected b y this . 1445Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setup Options f or A ll Turbulenc e ModelingFigur e 12.30: The Visc ous M odel D ialo g Box with the SBES Options Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1446Modeling Turbulenc e1447Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setup Options f or A ll Turbulenc e ModelingNote For the SDES and SBES mo dels , the Bounded C entral D ifferencing scheme (a vailable in the Solution M etho ds task page) is r ecommended f or momen tum discr etiza tion, and is the default setting . 12.16.27. Shielding F unc tions f or the BSL / SST / Transition SST D etached Eddy Simula tion M odel For the DES mo del with the BSL - mo del, SST - mo del, or the Transition SST mo del, the shielding (or blending) func tions F1 and F2 ar e defined in Equa tion 4.107 and Equa tion 4.118 in the Theor y Guide , respectively. Note tha t the F2 func tion is mor e conser vative than the F1 func tion. In addition, the shielding func tions DDES (D elayed DES) and IDDES (Impr oved D elayed DES), are descr ibed in DES with the BSL or SST k- ω Model and Impr oved D elayed D etached E ddy Simula tion (IDDES) in the Theor y Guide . DDES is r ecommended and is used as the default. 12.17. Defining Turbulenc e Boundar y Conditions For additional inf ormation, see the f ollowing sec tions: 12.17.1. Wall R oughness E ffects 12.17.2. The S palar t-Allmar as M odel 12.17.3. k-ε Models and k- ω Models 12.17.4. Reynolds S tress M odel 12.17.5. Large E ddy Simula tion M odel 12.17.1. Wall Roughness E ffects You ma y want to include the eff ects of the w all roughness on selec ted w all b oundar ies as par t of y our turbulen t simula tion. In such c ases , you c an sp ecify the r oughness par amet ers (r oughness heigh t and roughness c onstan t) in the dialo g boxes of the c orresponding w all b oundar ies (see Setting the Roughness P aramet ers (p.982)). Note Rough w alls c annot b e used t ogether with the f ollowing mo del c ombina tions: •an -equa tion mo del with enhanc ed w all tr eatmen t or the M enter-L echner near-w all tr eatmen t Note tha t the f ollowing ar e the r elevant -equa tion mo dels: –all of the - mo dels (tha t is, standar d, RNG, and r ealizable) –the R eynolds str ess mo del with the Linear P ressur e-Strain mo del selec ted –the detached edd y simula tion (DES) mo del with the Realizable k-epsilon option selec ted •the R eynolds str ess mo del with the Stress-Omega or Stress-BSL mo del selec ted •the tr ansition - - mo del Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1448Modeling Turbulenc e•the lar ge edd y simula tion (LES) mo del 12.17.2. The S palar t-Allmar as M odel When y ou ar e mo deling turbulen t flo ws in ANSY S Fluen t using the S palar t-Allmar as mo del, you must provide the b oundar y conditions f or in addition t o other mean solution v ariables .The b oundar y conditions f or at the w alls ar e in ternally tak en c are of b y ANSY S Fluen t, which ob viates the need f or your inputs .The b oundar y condition input f or , which y ou must en ter in ANSY S Fluen t, is the one a t inlet b oundar ies (f or e xample , velocity inlets , pressur e inlets). In man y situa tions , it is imp ortant to specify c orrect or r ealistic b oundar y conditions a t the inlets , because the inlet turbulenc e can signific antly affect the do wnstr eam flo w. 12.17.3. k-ε Models and k- ω Models When y ou ar e mo deling turbulen t flo ws in ANSY S Fluen t using one of the - mo dels or one of the - mo dels , you must pr ovide the b oundar y conditions f or and (or and ) in addition t o other mean solution v ariables .The b oundar y conditions f or and (or and ) at the w alls ar e in ternally taken c are of b y ANSY S Fluen t, which ob viates the need f or y our inputs .The b oundar y condition inputs for and (or and ), which y ou must en ter in ANSY S Fluen t, are the ones a t inlet b oundar ies (f or example , velocity inlets , pressur e inlets). In man y situa tions , it is imp ortant to sp ecify c orrect or r ealistic boundar y conditions a t the inlets , because the inlet turbulenc e can signific antly aff ect the do wnstr eam flow. See Determining Turbulenc e Paramet ers (p.914) for details ab out sp ecifying the b oundar y conditions for and (or and ) at the inlets . Additionally , you c an c ontrol whether or not t o set the turbulen t visc osity to zero within a laminar zone . If the fluid z one in question is laminar , the t ext command define/ boundary-condi- tions/fluid will c ontain an option c alled Set Turbulent Viscosity to zero within laminar zone? . By setting this option t o yes , ANSY S Fluen t will set b oth the pr oduc tion t erm in the turbulenc e transp ort equa tion and to zero. In c ontrast, when the Laminar Z one option is enabled in a Fluid cell z one c ondition dialo g box, only the pr oduc tion t erm is set t o zero. See Specifying a Laminar Z one (p.856) for details ab out laminar z ones . Imp ortant Note tha t the laminar z one f eature is also a vailable f or the S palar t-Allmar as and R eynolds stress mo dels . 12.17.4. Reynolds S tress M odel The sp ecific ation of turbulen t boundar y conditions f or the RSM is the same as f or the other turbulenc e models f or all b oundar ies e xcept a t boundar ies wher e flo w en ters the domain. Additional input metho ds ar e available f or these b oundar ies and ar e descr ibed her e. When y ou cho ose t o use the RSM, the default inlet b oundar y condition inputs r equir ed ar e iden tical to those r equir ed when the - mo del is ac tive.You c an input the turbulenc e quan tities using an y of the turbulenc e sp ecific ation metho ds descr ibed in Determining Turbulenc e Paramet ers (p.914). ANSY S 1449Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Defining Turbulenc e Boundar y ConditionsFluen t then uses the sp ecified turbulenc e quan tities t o der ive the R eynolds str esses a t the inlet fr om the assumption of isotr opy of turbulenc e: (12.4) (12.5) wher e is the nor mal R eynolds str ess c omp onen t in each dir ection. The b oundar y condition f or is det ermined in the same manner as f or the - turbulenc e mo dels (see Determining Turbulenc e Paramet ers (p.914)).To use this metho d, you will selec t K or Turbulen t In tensit y as the Reynolds- Stress S pecific ation M etho d in the appr opriate boundar y condition dialo g box. Alternately, you c an dir ectly sp ecify the R eynolds str esses b y selec ting the Reynolds-S tress C omp onen ts as the Reynolds-S tress S pecific ation M etho d in the b oundar y condition dialo g box.When this option is selec ted, you should input the R eynolds str esses dir ectly. You c an set the R eynolds str esses b y using c onstan t values , profile func tions of c oordina tes (see Pro- files (p.1051 )), or user-defined func tions (in the Fluen t Customiza tion M anual ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1450Modeling Turbulenc eFigur e 12.31: Specifying Inlet B oundar y Conditions f or the Re ynolds S tresses 12.17.5. Large E ddy Simula tion M odel It is p ossible t o sp ecify the magnitude of r andom fluc tuations of the v elocity comp onen ts at an inlet only if the v elocity inlet b oundar y condition is selec ted. In this c ase, you must sp ecify a Turbulenc e Intensit y tha t det ermines the magnitude of the r andom p erturba tions on individual mean v elocity comp onen ts as descr ibed in Inlet B oundar y Conditions f or Sc ale R esolving S imula tions (in the Theor y Guide ). For all b oundar y types other than v elocity inlets , the b oundar y conditions f or LES r emain the same as f or laminar flo ws. 1451Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Defining Turbulenc e Boundar y Conditions12.18. Providing an Initial G uess f or k and ε (or k and ω) For flo ws using one of the - mo dels , one of the - mo dels , or the RSM, the c onverged solutions or (for unst eady calcula tions) the solutions af ter a sufficien tly long time has elapsed should b e indep enden t of the initial v alues f or and (or and ). For b etter convergenc e, however, it is b eneficial t o use a reasonable initial guess f or and (or and ). In gener al, it is r ecommended tha t you star t from a suitable sta te of turbulenc e.When using a -in- sensitiv e wall tr eatmen t, it is cr itically imp ortant to sp ecify suitable turbulenc e fields . Guidelines ar e provided b elow: •If you w ere able t o sp ecify r easonable b oundar y conditions a t the inlet , it ma y be a go od idea t o comput e the initial v alues f or and (or and ) in the whole domain fr om these b oundar y values . See Initializing the S olution (p.2604 ) for details . •For mor e comple x flo ws (for e xample , flows with multiple inlets with diff erent conditions) it ma y be better to sp ecify the initial v alues in t erms of Turbulen t Intensit y and Turbulen t Visc osit y Ratio, which c an b oth be sp ecified a t the inlet(s). For Turbulen t Intensit y, , typic al values lie in the r ange of 1-10%. For Turbulen t Visc osit y Ratio, typic al values lie in the r ange of 1-100. –The v alue of can then b e comput ed fr om the Turbulen t Intensit y and the char acteristic mean v elocity magnitude of y our pr oblem (not e tha t in the f ollowing c alcula tion f or , must b e giv en as a fr action): (12.6) –You should sp ecify an initial guess f or so tha t the r esulting edd y visc osity ( ) is sufficien tly lar ge in compar ison t o the molecular visc osity. Suitable le vels of turbulen t visc osity are typic ally in the r ange of 1-100 times lar ger than the molecular visc osity. From this , you c an c omput e : (12.7) wher e is the Turbulen t Visc osit y Ratio which c an b e pr escr ibed a t the inlet and then used f or the domain initializa tion. –Similar ly, for the sp ecific dissipa tion r ate, : (12.8) Note tha t, for the RSM, Reynolds str esses ar e initializ ed aut oma tically using Equa tion 12.4 (p.1450 ) and Equa tion 12.5 (p.1450 ). 12.19. Solution S trategies f or Turbulen t Flow Simula tions Compar ed t o laminar flo ws, simula tions of turbulen t flo ws are mor e challenging in man y ways. For the Reynolds-a veraged appr oach, additional equa tions ar e solv ed f or the turbulenc e quan tities . Since the equa tions f or mean quan tities and the turbulen t quan tities ( , , , , or the R eynolds str esses) ar e strongly c oupled in a highly nonlinear fashion, it tak es mor e computa tional eff ort to obtain a c onverged turbulen t solution than t o obtain a c onverged laminar solution. The LES mo del, while emb odying a simpler , algebr aic mo del f or the sub grid-sc ale visc osity, requir es a tr ansien t solution on a v ery fine mesh. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1452Modeling Turbulenc eThe fidelit y of the r esults f or turbulen t flo ws is lar gely det ermined b y the turbulenc e mo del b eing used . Here ar e some guidelines tha t can enhanc e the qualit y of y our turbulen t flo w simula tions . For additional inf ormation, see the f ollowing sec tions: 12.19.1. Mesh G ener ation 12.19.2. Accur acy 12.19.3. Convergenc e 12.19.4. RSM-S pecific S olution S trategies 12.19.5. LES-S pecific S olution S trategies 12.19.1. Mesh G ener ation The f ollowing ar e suggestions t o follow when gener ating the mesh f or use in y our turbulen t flo w simula tion: •First imagine the flo w under c onsider ation, then iden tify the main flo w features e xpected in the flo w using your ph ysical in tuition or an y da ta for a similar flo w situa tion. Gener ate a mesh tha t can r esolv e the major features tha t you e xpect. •If the flo w is w all-b ounded and the w all is e xpected t o aff ect the flo w signific antly, you should tak e addi- tional c are when gener ating the mesh. See Grid R esolution f or R ANS M odels (p.1384 ) and Wall B oundar y Layers (p.1388 ) for guidelines . 12.19.2. Accur acy The suggestions b elow ar e pr ovided t o help y ou obtain b etter accur acy in y our r esults: •Use the turbulenc e mo del tha t is b etter suit ed f or the salien t features y ou e xpect to see in the flo w (see Choosing a Turbulenc e Model (p.1377 )). •Because the mean quan tities ha ve lar ger gr adien ts in turbulen t flo ws than in laminar flo ws, it is r ecommen- ded tha t you use high-or der schemes f or the c onvection t erms.This is esp ecially tr ue if y ou emplo y a tr ian- gular or t etrahedr al mesh. Note tha t excessiv e numer ical diffusion ad versely aff ects the solution accur acy, even with the most elab orate turbulenc e mo del. •In some flo w situa tions in volving inlet b oundar ies, the flo w do wnstr eam of the inlet is dic tated b y the boundar y conditions a t the inlet. In such c ases , you should e xercise c are to mak e sur e tha t reasonably realistic b oundar y values ar e sp ecified . 12.19.3. Convergenc e The suggestions b elow ar e pr ovided t o help y ou enhanc e convergenc e for turbulen t flo w calcula tions: •Starting with e xcessiv ely cr ude initial guesses f or mean and turbulenc e quan tities ma y cause the solution to div erge. A saf e appr oach is t o star t your c alcula tion using c onser vative (small) under-r elaxa tion par amet ers and (f or the densit y-based solv ers) a c onser vative Courant numb er, and incr ease them gr adually as the it- erations pr oceed and the solution b egins t o settle do wn. •It is also helpful f or fast er convergenc e to star t with r easonable initial guesses f or the and (or and ) fields . Particular ly when a -insensitiv e wall tr eatmen t is used , it is imp ortant to star t with a sufficien tly develop ed turbulenc e field , as r ecommended in Providing an Initial G uess f or k and ε (or k and ω) (p.1452 ), to avoid the need f or an e xcessiv e numb er of it erations t o de velop the turbulenc e field . 1453Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Solution S trategies f or Turbulen t Flow Simula tions•When y ou ar e using the RNG - mo del, an appr oach tha t migh t help y ou achie ve better convergenc e is to obtain a solution with the standar d - mo del b efore swit ching t o the RNG mo del. Due t o the additional nonlinear ities in the RNG mo del, lower under-r elaxa tion fac tors and (f or the densit y-based solv ers) a lo wer Courant numb er migh t also b e nec essar y. Note tha t when y ou use the enhanc ed w all tr eatmen t (EWT- ), you ma y sometimes find dur ing the calcula tion tha t the r esidual f or is reported t o be zero.This happ ens when y our flo w is such tha t is less than 200 in the en tire flo w domain, and is obtained fr om the algebr aic f ormula ( Equa- tion 4.342 in the Theor y Guide ) inst ead of fr om its tr ansp ort equa tion. 12.19.4. RSM-S pecific S olution S trategies Using the RSM cr eates a high degr ee of c oupling b etween the momen tum equa tions and the turbulen t stresses in the flo w, and ther efore the c alcula tion c an b e mor e pr one t o stabilit y and c onvergenc e difficulties than with the - mo dels .When y ou use the RSM, ther efore, you ma y need t o adopt sp ecial solution str ategies in or der t o obtain a c onverged solution. The f ollowing str ategies ar e gener ally r e- commended: •Begin the c alcula tions using the standar d - mo del. Turn on the RSM and use the - solution da ta as a starting p oint for the RSM c alcula tion. •Use lo w under-r elaxa tion fac tors (0.2 t o 0.3) and (f or the densit y-based solv ers) a lo w Courant numb er for highly swir ling flo ws or highly c omple x flo ws. In these c ases , you ma y need t o reduc e the under-r elaxa tion factors b oth f or the v elocities and f or all of the str esses . Instr uctions f or setting these solution par amet ers ar e pr ovided b elow. If you ar e applying the RSM t o predic tion of a highly swir ling flo w, you will w ant to consider the solution str ategies discussed in Swirling and R otating F lows (p.1211 ) as w ell. 12.19.4.1. Under -Relaxation of the R eynolds Str esses ANSY S Fluen t applies under-r elaxa tion t o the R eynolds str esses .You c an set under-r elaxa tion fac tors using the Solution C ontrols Task P age (p.3606 ). Solution → Controls The default settings of 0.5 ar e recommended f or most c ases .You ma y be able t o incr ease these settings and sp eed up the c onvergenc e when the RSM solution b egins t o converge. In some situa tions , when p oor c onvergenc e is obser ved one migh t facilita te the c onvergenc e rates by mo difying some of the under-r elaxa tion v alues whilst lea ving the others unchanged .This migh t be a mor e succ essful appr oach than the simple sc aling of all under-r elaxa tion v alues . 12.19.4.2. Disabling C alculation Up dat es of the R eynolds Str esses In some instanc es, you ma y want to let the cur rent Reynolds str ess field r emain fix ed, skipping the solution of the R eynolds tr ansp ort equa tions while solving the other tr ansp ort equa tions .You c an enable/disable all R eynolds str ess equa tions in the Equa tions dialo g box. Solution → Controls Equa tions ... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1454Modeling Turbulenc e12.19.4.3. Residual R eporting for the RSM When y ou use the RSM f or turbulenc e, ANSY S Fluen t reports the equa tion r esiduals f or the individual Reynolds str ess tr ansp ort equa tions .You c an apply the usual c onvergenc e cr iteria to the R eynolds stress r esiduals: nor maliz ed r esiduals in the r ange of usually indic ate a pr actically-c onverged solution. However, you ma y need t o apply tigh ter convergenc e cr iteria (b elow ) to ensur e full convergenc e. 12.19.5. LES-S pecific S olution S trategies Large edd y simula tion in volves running a tr ansien t solution fr om some initial c ondition, on an appr o- priately fine mesh, using an appr opriate time st ep siz e.The solution must b e run long enough t o become indep enden t of the initial c ondition and t o enable the sta tistics of the flo w field t o be det ermined . The f ollowing ar e suggestions t o follow when r unning a lar ge edd y simula tion: 1.Start by running a st eady-sta te flo w simula tion using a R eynolds-a veraged turbulenc e mo del such as standar d - , - , or e ven RSM. Run un til the flo w field is r easonably c onverged and then use the solve/initialize/init-turb-vel-fluctuations text command t o gener ate the instan taneous velocity field out of the st eady-sta te RANS r esults .This c ommand must b e execut ed b efore LES is enabled . This option is a vailable f or all R ANS-based mo dels and it will cr eate a much mor e realistic initial field f or the LES r un. Additionally , it will help in r educing the time needed f or the LES simula tion t o reach a sta tist- ically stable mo de.This st ep is optional. 2.When y ou enable LES, ANSY S Fluen t will aut oma tically tur n on the unst eady solv er option and choose the sec ond-or der implicit f ormula tion. You will need t o set the appr opriate time st ep siz e and all the needed solution par amet ers. (See User Inputs f or Time-D ependen t Problems (p.2627 ) for guidelines on setting solution par amet ers f or tr ansien t calcula tions in gener al.) F or the pr essur e- based solv er, the b ounded c entral diff erencing spa tial discr etiza tion scheme will b e aut oma tically selec ted f or momen tum equa tions; both the b ounded c entral-diff erencing and pur e central-diff er- encing schemes ar e available f or all equa tions when r unning LES simula tions . For the densit y-based solv er, the b ounded c entral diff erencing scheme c an b e used f or the flo w equa tions , though it is not selec ted b y default. 3.Run LES un til the flo w becomes sta tistic ally st eady.The b est w ay to see if the flo w is fully de velop ed and statistic ally st eady is t o monit or forces and solution v ariables (f or e xample , velocity comp onen ts or pr essur e) at selec ted lo cations in the flo w. 4.Zero out the initial sta tistics using the solve/initialize/init-flow-statistics text command . Before you r estar t the solution, enable Data S ampling f or Time S tatistics in the Run Calcula tion Task P age (p.3640 ), as descr ibed in User Inputs f or Time-D ependen t Problems (p.2627 ). With this option enabled , ANSY S Fluen t will ga ther da ta for time sta tistics while p erforming a lar ge edd y simula tion. You c an set the Sampling In terval such tha t Data S ampling f or Time S tatistics can b e performed a t the sp ecified fr equenc y.When Data S ampling f or Time S tatistics is enabled , the sta tistics c ollec ted a t each sampling in terval can b e postpr ocessed and y ou c an then view b oth the mean and the r oot-mean-squar e-er ror (RMSE) v alues in ANSY S Fluen t.The Sampled Time displa ys the time p eriod over which da ta has b een sampled f or the p ostpr ocessing of the mean and RMSE values . As long as the time st ep siz e has b een c onstan t, dividing this b y the time st ep siz e yields the numb er of da ta sets tha t ha ve been c ollec ted. If the time st ep siz e is v aried, every contribution of da ta sets sampled is aut oma tically w eigh ted b y the cur rent time st ep siz e. 1455Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Solution S trategies f or Turbulen t Flow Simula tions5.Continue un til you get sta tistic ally stable da ta.The dur ation of the simula tion c an b e det ermined b efore- hand b y estima ting the mean flo w residenc e time in the solution domain ( , wher e is the char acter- istic length of the solution domain and is a char acteristic mean flo w velocity).The simula tion should be run f or a t least a f ew mean flo w residenc e times . Instr uctions f or setting the solution par amet ers f or LES ar e pr ovided b elow. 12.19.5.1. Temp oral D iscr etization ANSY S Fluen t provides b oth first-or der and sec ond-or der t emp oral discr etiza tions . For LES, the sec ond- order discr etiza tion is r ecommended . Solution → Metho ds 12.19.5.2. Spatial D iscr etization Overly diffusiv e schemes such as the first-or der up wind scheme should b e avoided , because the y may unduly damp out the ener gy of the r esolv ed eddies .The c entral-diff erencing based schemes ar e recommended f or all equa tions when y ou use the LES mo del. ANSY S Fluen t provides t wo central- differencing based schemes: pur e central-diff erencing and bounded central-diff erencing .The b ounded scheme is the default option f or momen tum discr etiza tion when y ou selec t LES, SAS, DES, SDES, or SBES. Solution → Metho ds 12.20. Postpr ocessing f or Turbulen t Flows ANSY S Fluen t provides p ostpr ocessing options f or displa ying , plotting , and r eporting v arious turbulenc e quan tities , which include the main solution v ariables and other auxiliar y quan tities . Turbulenc e quan tities tha t can b e reported f or the S palar t-Allmar as mo del ar e as f ollows: •Modified Turbulen t Visc osit y •Turbulen t Visc osit y •Effective Visc osit y •Turbulen t Visc osit y Ratio •Effective Thermal C onduc tivit y •Effective Prandtl N umb er •Wall Yplus •Curvature Correction F unc tion fr (only when the cur vature correction is enabled) Turbulenc e quan tities tha t can b e reported f or the DES mo del in c ombina tion with the S palar t-All- mar as mo del ar e as f ollows: •all of the quan tities a vailable f or the S palar t-Allmar as mo del Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1456Modeling Turbulenc e•DES TKE D issipa tion M ultiplier •Normaliz ed Q C riterion •Q C riterion •Lamb da 2 C riterion Note For a D etached E ddy Simula tion with the S palar t-Allmar as mo del, the DES TKE D issipa tion Multiplier represen ts the func tion in Equa tion 4.245 . Turbulenc e quan tities tha t can b e reported f or the - mo dels ar e as f ollows: •Turbulen t Kinetic E nergy (k) •Turbulen t Intensit y •Turbulen t Dissipa tion R ate (E psilon) •Produc tion of k •Turbulen t Visc osit y •Effective Visc osit y •Turbulen t Visc osit y Ratio •Effective Thermal C onduc tivit y •Effective Prandtl N umb er •Wall Ystar •Wall Yplus •Turbulen t Re ynolds N umb er (Re_y) (only when the enhanc ed w all tr eatmen t is used f or the near-w all treatmen t) •Curvature Correction F unc tion fr (only when the cur vature correction is enabled) Turbulenc e quan tities tha t can b e reported f or the DES mo del in c ombina tion with the R ealizable - model ar e as f ollows: •all of the quan tities a vailable f or the R ealizable - mo del •DES TKE D issipa tion M ultiplier •Normaliz ed Q C riterion •Q C riterion 1457Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Postpr ocessing f or Turbulen t Flows•Lamb da 2 C riterion Note For a D etached E ddy Simula tion with the R ealizable - mo del, the DES TKE D issipa tion Multiplier represen ts the func tion in Equa tion 4.252 . Turbulenc e quan tities tha t can b e reported f or the - mo dels ar e as f ollows: •Turbulen t Kinetic E nergy (k) •Turbulen t Intensit y •Turbulen t Dissipa tion R ate (E psilon) •Intermitt enc y •Specific D issipa tion R ate (Omega) •Produc tion of k •Turbulen t Visc osit y •Effective Visc osit y •Turbulen t Visc osit y Ratio •Effective Thermal C onduc tivit y •Effective Prandtl N umb er •Wall Ystar •Wall Yplus •Turbulen t Re ynolds N umb er (Re_y) •Curvature Correction F unc tion fr (only when the cur vature correction is enabled) Turbulenc e quan tities tha t can b e reported f or the S tandar d and BSL - mo del in c ombina tion with the SAS mo del ar e as f ollows: •all of the quan tities a vailable f or the - mo del •Normaliz ed Q C riterion •Q C riterion •Lamb da 2 C riterion Turbulenc e quan tities tha t can b e reported f or the BSL or SST - mo del in c ombina tion with the DES model ar e as f ollows: •all of the quan tities a vailable f or the - mo dels Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1458Modeling Turbulenc e•DES TKE D issipa tion M ultiplier •Normaliz ed Q C riterion •Q C riterion •Lamb da 2 C riterion Note For a D etached E ddy Simula tion with BSL / SST ,DES TKE D issipa tion M ultiplier represen ts the func tion in Equa tion 4.256 and in Equa tion 4.260 , dep ending on the sp ecified model. Within the DES c oncept, the DES TKE D issipa tion M ultiplier incr eases the destr uction term in the tr ansp ort equa tion f or the turbulenc e kinetic ener gy in LES r egions ( ). This incr ease in destr uction t erms r educ es the edd y visc osity in LES r egions . Turbulenc e quan tities tha t can b e reported f or the BSL or SST - mo del in c ombina tion with the Shielded D etached E ddy Simula tion (SDES) mo del or the S tress-B lended E ddy Simula tion (SBES) mo del are as f ollows: •all of the quan tities a vailable f or the - mo dels •Shielding F unc tion f or SBES or SDES •Normaliz ed Q C riterion •Q C riterion •Lamb da 2 C riterion Turbulenc e quan tities tha t can b e reported f or the tr ansition - - mo del ar e as f ollows: •Turbulen t Kinetic E nergy (k) •Laminar K inetic E nergy •Total F luctuation E nergy •Turbulen t Intensit y •Turbulen t Dissipa tion R ate (E psilon) •Specific D issipa tion R ate (Omega) •Produc tion of k •Produc tion of laminar k •Turbulen t Visc osit y •Turbulen t Visc osit y (lar ge-sc ale) •Turbulen t Visc osit y (small-sc ale) •Effective Visc osit y 1459Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Postpr ocessing f or Turbulen t Flows•Turbulen t Visc osit y Ratio •Effective Thermal C onduc tivit y •Effective Prandtl N umb er •Wall Ystar •Wall Yplus •Turbulen t Re ynolds N umb er (Re_y) Turbulenc e quan tities tha t can b e reported f or the Transition SST mo del ar e as f ollows: •Turbulen t Kinetic E nergy (k) •Turbulen t Intensit y •Turbulen t Dissipa tion R ate (E psilon) •Intermitt enc y •Intermitt enc y Effective •Momen tum Thick ness Re •Geometr ic Roughness H eigh t •Specific D issipa tion R ate (Omega) •Produc tion of k •Turbulen t Visc osit y •Effective Visc osit y •Turbulen t Visc osit y Ratio •Effective Thermal C onduc tivit y •Effective Prandtl N umb er •Wall Ystar •Wall Yplus •Turbulen t Re ynolds N umb er (Re_y) •Curvature Correction F unc tion fr (only when the cur vature correction is enabled) Turbulenc e quan tities tha t can b e reported f or the Transition SST mo del in c ombina tion with the SAS model ar e as f ollows: •all of the quan tities a vailable f or the Transition SST mo del •Normaliz ed Q C riterion Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1460Modeling Turbulenc e•Q C riterion •Lamb da 2 C riterion Turbulenc e quan tities tha t can b e reported f or the Transition SST mo del in c ombina tion with the DES model ar e as f ollows: •all of the quan tities a vailable f or the Transition SST mo del •DES TKE D issipa tion M ultiplier •Normaliz ed Q C riterion •Q C riterion •Lamb da 2 C riterion Note For the Transition SST mo del in c ombina tion with the DES mo del, DES TKE D issipa tion Multiplier represen ts the func tion in Equa tion 4.259 and in Equa tion 4.260 de- pending on the sp ecified mo del. Within the DES c oncept, the DES TKE D issipa tion M ultiplier increases the destr uction t erm in the tr ansp ort equa tion f or the turbulenc e kinetic ener gy in LES r egions ( ).This incr ease in destr uction t erms r educ es the edd y visc osity in LES regions . Turbulenc e quan tities tha t can b e reported f or the Transition SST mo del in c ombina tion with the Shielded D etached E ddy Simula tion (SDES) mo del or the S tress-B lended E ddy Simula tion (SBES) mo del are as f ollows: •all of the quan tities a vailable f or the Transition SST mo del •Shielding F unc tion f or SBES or SDES •Normaliz ed Q C riterion •Q C riterion •Lamb da 2 C riterion Turbulenc e quan tities tha t can b e reported f or the RSM ar e as f ollows: •Turbulen t Kinetic E nergy (k) •Turbulen t Intensit y •UU Re ynolds S tress •VV Re ynolds S tress •WW Re ynolds S tress •UV Re ynolds S tress •VW Re ynolds S tress 1461Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Postpr ocessing f or Turbulen t Flows•UW Re ynolds S tress •Turbulen t Dissipa tion R ate (E psilon) •Specific D issipa tion R ate (Omega) ( -based R eynolds str ess mo dels only) •Produc tion of k •Turbulen t Visc osit y •Effective Visc osit y •Turbulen t Visc osit y Ratio •Effective Thermal C onduc tivit y •Effective Prandtl N umb er •Wall Ystar •Wall Yplus •Turbulen t Re ynolds N umb er (Re_y) ( -based R eynolds str ess mo dels only) Turbulenc e quan tities tha t can b e reported f or the -based R eynolds str ess mo dels in c ombina tion with the SAS mo del ar e as f ollows: •all of the quan tities a vailable f or the RSM mo del •Normaliz ed Q C riterion •Q C riterion •Lamb da 2 C riterion Turbulenc e quan tities tha t can b e reported f or the SAS mo del in c ombina tion with the SST - mo del are as f ollows: •Turbulen t Kinetic E nergy (k) •Turbulen t Intensit y •Turbulen t Dissipa tion R ate (E psilon) •Intermitt enc y •Specific D issipa tion R ate (Omega) •Produc tion of k •Turbulen t Visc osit y •Effective Visc osit y •Turbulen t Visc osit y Ratio •Effective Thermal C onduc tivit y Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1462Modeling Turbulenc e•Effective Prandtl N umb er •Wall Yplus •Wall Ystar •Curvature Correction F unc tion fr (only when the cur vature correction is enabled) •Normaliz ed Q C riterion •Q C riterion •Lamb da 2 C riterion Turbulenc e quan tities tha t can b e reported f or the LES mo del ar e as f ollows: •Turbulenc e Kinetic E nergy •Turbulenc e In tensit y •Subgrid K inetic E nergy •Produc tion of k •Subgrid Turbulen t Visc osit y •Subgrid E ffective Visc osit y •Subgrid Turbulen t Visc osit y Ratio •Subgrid F ilter L ength •Subgrid Test-F ilter L ength •Subgrid D issipa tion R ate •Subgrid D ynamic Visc osit y Const •Subgrid D ynamic P randtl N umb er •Subgrid D ynamic Sc of S pecies •Subt est K inetic E nergy •Effective Thermal C onduc tivit y •Effective Prandtl N umb er •Wall Ystar •Wall Yplus •Normaliz ed Q C riterion •Q C riterion •Lamb da 2 C riterion 1463Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Postpr ocessing f or Turbulen t FlowsAdditional turbulenc e quan tities c an b e reported f or the Emb edded LES (ELES) mo del. Note Within the Emb edded LES z one , the mo deled edd y visc osity is det ermined b y an algebr aic subgrid-sc ale edd y visc osity mo del. The global turbulenc e mo del is either fr ozen or , if it is either SAS, DES, SDES, or SBES with an under lying t wo-equa tion R ANS mo del, runs in a "passiv e mo de", tha t is without aff ecting the momen tum equa tions . Hence, most turbulenc e postpr ocessing in the Emb edded LES z one r efers t o the fr ozen or "passiv e" global turbulenc e mo del. Special c are is nec essar y with the mo deled edd y visc osity, because ther e ar e two to consider : one fr om the fr ozen / passiv e global turbulenc e mo del; and one fr om the "lo cal" algebr aic sub grid-sc ale mo del tha t is r unning within the Emb edded LES z one and ac tually aff ects the momen tum equa tions . •Some p ostpr ocessing quan tities r efer to a "passiv e" global turbulenc e mo del or ar e zero if the global mo del cannot r un in "passiv e" mo de and ther efore is fr ozen in the Emb edded LES z one . –Turbulen t Visc osit y –Turbulen t Visc osit y Ratio •In the Emb edded LES z one , the sub grid-sc ale edd y visc osity from the lo cal algebr aic mo del, which ac tually affects the momen tum equa tions , is displa yed as: –LES S ubgrid Turbulen t Visc osit y •The following quan tities ar e sp ecific t o the D ynamic LES sub grid-sc ale edd y visc osity mo dels .They are available in Emb edded LES z ones if the Dynamic S magor insk y mo del is used in an y Emb edded LES z one; they are also a vailable f or global LES when the Smagor insk y-Lilly sub grid-sc ale mo del is selec ted with the Dynamic S tress option enabled or when the Kinetic-E nergy Transp ort sub grid-sc ale mo del is selec ted: –Subgrid Test-F ilter L ength –Subgrid D ynamic Visc osit y Const –Subt est K inetic E nergy All of these v ariables c an b e found in the Turbulenc e... categor y of the v ariable selec tion dr op-do wn list tha t app ears in p ostpr ocessing dialo g boxes. See Field F unction D efinitions (p.2959 ) for their definitions . For additional inf ormation, see the f ollowing sec tions: 12.20.1. Custom F ield F unctions f or Turbulenc e 12.20.2. Postpr ocessing Turbulen t Flow Statistics 12.20.3. Troublesho oting 12.20.1. Custom F ield F unc tions f or Turbulenc e In addition t o the quan tities list ed in Postpr ocessing f or Turbulen t Flows (p.1456 ), above, you c an define your o wn turbulenc e quan tities using the Custom F ield F unction C alcula tor D ialog Box (p.3797 ). User-D efineed → Field F unc tions → Custom... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1464Modeling Turbulenc eThe f ollowing func tions ma y be useful: •the r atio of pr oduc tion of to its dissipa tion ( ) •the r atio of the mean flo w to turbulen t time sc ale, ( ) •the R eynolds str esses der ived fr om the B oussinesq f ormula (f or e xample , ) 12.20.2. Postpr ocessing Turbulen t Flow Statistics As descr ibed in Large E ddy Simula tion (LES) M odel (in the Theor y Guide ), LES in volves the solution of a transien t flo w field , but it is the mean flo w quan tities tha t are of in terest fr om an engineer ing standp oint. For all other turbulen t flo w, if Data S ampling f or Time S tatistics is enabled in the Run C alcula tion Task P age (p.3640 ), ANSY S Fluen t ga thers da ta for time sta tistics while p erforming the simula tion. The statistics tha t ANSY S Fluen t collec ts at each sampling in terval (which c onsists of the mean and the root-mean-squar e-er ror (RMSE) v alues) c an b e postpr ocessed b y selec ting Unstead y Statistics ... in any of the p ostpr ocessing dialo g boxes.You c an view se veral variables tha t include , but ar e not limit ed to, shear str esses ( Resolv ed UV/UW/VW Re ynolds S tress), flow hea t flux es (Resolv ed UT/VT/W T H eat Flux), and sp ecies sta tistics ( RMSE M ass F raction of species and Mean M ass F raction of sp ecies). If you selec t Unstead y Wall S tatistics ... in an y of the p ostpr ocessing dialo g boxes, you c an view w all statistics such as Mean P ressur e Coefficien t,Mean Wall S hear S tress,Mean X-W all S hear S tress, Mean Y-W all S hear S tress,Mean Z-W all S hear S tress,Mean S kin F riction C oefficien t,Mean S urface Heat Flux,Mean S urface Heat Transf er C oef.,Mean S urface Nusselt N umb er,Mean S urface Stanton N umb er. Note tha t these quan tities ar e only the sta tistic al evalua tion of sampled solution data, and do not c ontain an y kind of mo deled turbulen t fluc tuations . See Postpr ocessing f or Time- Dependen t Problems (p.2645 ) for details . The Sampled Time field displa ys the time p eriod over which da ta has b een sampled f or the p ostpr o- cessing of the mean and RMSE v alues . As long as the time st ep siz e has b een c onstan t, dividing this by the time st ep siz e yields the numb er of da ta sets tha t ha ve been c ollec ted. If the time st ep siz e is varied, every contribution of da ta sets sampled is aut oma tically w eigh ted b y the cur rent time st ep size. Imp ortant Note tha t mean statistics ar e collec ted only in in terior c ells and not on w all sur faces. Therefore, when no de or c ell v alues of mean quan tities ar e plott ed on the w all sur face, you are ac tually plotting v alues in nearb y cells a ttached t o the w all. If you w ant to control wha t set of v ariables ar e available f or p ostpr ocessing , open the Sampling Options dialo g box and enable or disable the sta tistics sho wn in Figur e 12.32: The S ampling Options D ialog Box (p.1466 ). Solution → Run C alcula tion → Sampling Options ... 1465Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Postpr ocessing f or Turbulen t FlowsFigur e 12.32: The S ampling Options D ialo g Box Imp ortant When including or e xcluding sta tistics on v ariables , it is r ecommended tha t you r e-initializ e the flo w sta tistics . 12.20.3. Troublesho oting You c an use the p ostpr ocessing options not only f or the pur pose of in terpreting y our r esults but also for in vestiga ting an y anomalies tha t ma y app ear in the solution. For instanc e, you ma y want to plot contours of the field t o check if ther e ar e an y regions wher e is er roneously lar ge or small. You should see a high region in the r egion wher e the pr oduc tion of is lar ge.You ma y want to displa y the turbulen t visc osity ratio field in or der t o see whether or not the turbulenc e tak es full eff ect. Usually the turbulen t visc osity is a t least t wo or ders of magnitude lar ger than molecular visc osity for fully-de- velop ed turbulen t flo ws mo deled using the R ANS appr oach (tha t is, not using LES). You ma y also w ant to check whether y ou ar e using an adequa te near-w all mesh when using a -insensitiv e wall tr eatmen t (see Grid R esolution f or R ANS M odels (p.1384 ) for guidelines). For E WT- , you c an also displa y filled contours of (turbulen t Reynolds numb er) o verlaid on the mesh (see Enhanc ed Wall Treatmen t ε- Equa tion (E WT-ε) in the Theor y Guide for mor e details). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1466Modeling Turbulenc eChapt er 13: Modeling H eat Transf er This chapt er pr ovides details ab out the hea t transf er mo dels a vailable in ANSY S Fluen t. Information is presen ted in the f ollowing sec tions: 13.1. Introduction 13.2. Modeling C onduc tive and C onvective Heat Transf er 13.3. Modeling R adia tion 13.4. Modeling P eriodic H eat Transf er 13.1. Introduc tion The flo w of ther mal ener gy from ma tter o ccup ying one r egion in spac e to ma tter o ccup ying a diff erent region in spac e is k nown as hea t transf er. Heat transf er can o ccur b y thr ee main mechanisms: conduc tion, convection, and r adia tion. Physical mo dels in volving c onduc tion and/or c onvection only ar e the simplest (Modeling C onduc tive and C onvective Heat Transf er (p.1467 )), while buo yancy-dr iven flo w or na tural convection ( Natural C onvection and B uoyancy-Driven F lows (p.1476 )), and flo w in volving r adia tion (Modeling R adia tion (p.1489 )) are mor e comple x. Depending on y our pr oblem, ANSY S Fluen t will solv e a variation of the ener gy equa tion tha t tak es in to acc oun t the hea t transf er metho ds y ou ha ve sp ecified . ANSY S Fluen t is also able t o pr edic t hea t transf er in p eriodically r epeating geometr ies ( Modeling P eri- odic H eat Transf er (p.1567 )), ther efore gr eatly r educing the r equir ed c omputa tional eff ort in c ertain c ases . 13.2. Modeling C onduc tive and C onvective Heat Transf er ANSY S Fluen t allo ws you t o include hea t transf er within the fluid and/or solid r egions in y our mo del. Problems r anging fr om ther mal mixing within a fluid t o conduc tion in c omp osite solids c an ther efore be handled b y ANSY S Fluen t. When y our ANSY S Fluen t mo del includes hea t transf er y ou will need t o enable the r elevant ph ysical models , supply ther mal b oundar y conditions , and en ter ma terial pr operties (which ma y vary with t em- perature) tha t go vern hea t transf er. For inf ormation ab out hea t transf er theor y, see Heat Transf er Theor y in the Theor y Guide . Information ab out hea t transf er theor y and ho w to set up and use hea t transf er in your ANSY S Fluen t mo del is pr esen ted in the f ollowing subsec tions: 13.2.1. Solving H eat Transf er Problems 13.2.2. Solution S trategies f or H eat Transf er M odeling 13.2.3. Postpr ocessing H eat Transf er Q uantities 13.2.4. Natural Convection and B uoyancy-Driven F lows 13.2.5. Shell C onduc tion C onsider ations 13.2.1. Solving H eat Transf er P roblems The pr ocedur e for setting up a hea t transf er pr oblem is descr ibed b elow. Note tha t this pr ocedur e in- cludes only those st eps nec essar y for the hea t transf er mo del itself ; you will need t o define the other settings (f or e xample , other mo dels , boundar y conditions) as usual. 1467Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.1.To ac tivate the c alcula tion of hea t transf er, enable the ener gy equa tion b y right-click ing Energy in the tree (under Setup/M odels ) and click ing On in the menu tha t op ens. Setup → Models → Energy On Figur e 13.1: Enabling the E nergy Equa tion 2.(Optional, pressur e-based solv er only .) If you ar e mo deling visc ous flo w and y ou w ant to include the visc ous heating t erms in the ener gy equa tion, enable the Visc ous H eating option in the Visc ous M odel dialo g box. Setup → Models → Visc ous Edit... As not ed in Inclusion of the Viscous D issipa tion Terms in the Theor y Guide , the visc ous hea ting terms in the ener gy equa tion ar e (b y default) ignor ed b y ANSY S Fluen t when the pr essur e-based solv er is used .They are alw ays included f or the densit y-based solv er.Viscous dissipa tion should be enabled when the shear str ess in the fluid is lar ge (f or e xample , in lubr ication pr oblems) and/or in high-v elocity, compr essible flo ws. See Equa tion 5.9 in the Theor y Guide . 3.Define ther mal b oundar y conditions a t flo w inlets , flow outlets , and w alls.The b oundar y condition dialo g boxes c an b e op ened b y right-click ing the b oundar y name in the tr ee (under Setup/B oundar y Conditions ) and click ing Edit... in the menu tha t op ens; alternatively, you c an op en them fr om the Boundar y Condi- tions task page: Setup → Boundar y Conditions At flo w inlets and e xits y ou will set the t emp erature; at walls y ou ma y use an y of the f ollowing ther mal c onditions: •specified hea t flux •specified t emp erature •convective hea t transf er Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1468Modeling H eat Transf er•external r adia tion •combined e xternal r adia tion and e xternal c onvective hea t transf er Thermal B oundar y Conditions a t Walls (p.984) provides details on the mo del inputs tha t go vern these ther mal b oundar y conditions .The default ther mal b oundar y condition a t inlets is a sp ecified temp erature of 300 K; at walls the default c ondition is z ero hea t flux (adiaba tic). See Cell Z one and Boundar y Conditions (p.835) for details ab out b oundar y condition inputs . Imp ortant If your hea t transf er applic ation in volves two separ ated fluid r egions , see the inf ormation provided b elow. 4.Define ma terial pr operties f or hea t transf er. Setup → Materials Heat capacit y and ther mal c onduc tivit y must b e defined , and y ou c an sp ecify man y pr operties as func tions of t emp erature as descr ibed in Physical Properties (p.1079 ). 13.2.1.1. Limiting the P redic ted Temp eratur e Range For stabilit y reasons , ANSY S Fluen t includes a limit on the pr edic ted t emp erature range .The pur pose of the t emp erature ceiling and flo or is t o impr ove the stabilit y of c alcula tions in which the t emp erature should ph ysically lie within k nown limits . Sometimes in termedia te solutions of the equa tions giv e rise t o temp eratures b eyond these limits f or which pr operty definitions , and so on, are not w ell defined . The t emp erature limits k eep the t emp eratures within the e xpected r ange f or y our pr oblem. If the ANSY S Fluen t calcula tion pr edic ts a t emp erature ab ove the maximum limit , the st ored t emp erature values ar e “pegged ” at this maximum v alue .The default f or the t emp erature ceiling is 5000 K. If the ANSY S Fluen t calcula tion pr edic ts a t emp erature below the minimum limit , the st ored t emp erature values ar e “pegged ” at this minimum v alue .The default f or the t emp erature minimum is 1 K. If you e xpect the t emp erature in y our domain t o exceed 5000 K, use the Solution Limits dialo g box to incr ease the Maximum S tatic Temp erature. Solution → Controls Limits ... 13.2.1.2. Mo deling H eat Transfer in Two Separ ated F luid R egions If your hea t transf er applic ation in volves two fluid r egions separ ated b y a solid z one or a w all, as illus- trated in Figur e 13.2: Typic al C oun terflow H eat Exchanger In volving H eat Transf er B etween Two Sep- arated F luid S treams (p.1470 ), you will need t o define the pr oblem with some c are. Specific ally: •You should not use outflo w boundar y conditions in either fluid . •You c an establish separ ate fluid pr operties b y selec ting a diff erent fluid ma terial for each z one . For sp ecies calcula tions , however, you c an only selec t a single mix ture ma terial for the en tire domain. 1469Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling C onduc tive and C onvective Heat Transf erFigur e 13.2: Typic al C oun terflow H eat Exchanger In volving H eat Transf er B etween Two Separ ated Fluid S treams 13.2.2. Solution S trategies f or H eat Transf er M odeling Although man y simple hea t transf er pr oblems c an b e succ essfully solv ed using the default solution paramet ers assumed b y ANSY S Fluen t, you ma y acc elerate the c onvergenc e of y our pr oblem and/or impr ove the stabilit y of the solution pr ocess using some of the guidelines pr ovided in this sec tion. 13.2.2.1. Under -Relaxation of the E ner gy Equation When y ou use the pr essur e-based solv er, ANSY S Fluen t under-r elax es the ener gy equa tion using the under-r elaxa tion par amet er defined b y you in the Solution C ontrols task page , as descr ibed in Setting Under-R elaxa tion F actors (p.2573 ). Solution → Controls If you ar e using the non-adiaba tic non-pr emix ed c ombustion mo del, you will set the ener gy under- relaxa tion fac tor as usual but y ou will also set an under-r elaxa tion fac tor for temp erature, as descr ibed below. ANSY S Fluen t uses a default under-r elaxa tion fac tor of 1.0 f or the ener gy equa tion, regar dless of the form in which it is solv ed (t emp erature or en thalp y). In pr oblems wher e the ener gy field impac ts the fluid flo w (via t emp erature-dep enden t properties or buo yancy) you should use a lo wer v alue f or the under-r elaxa tion fac tor, in the r ange of 0.8–1.0. In pr oblems wher e the flo w field is dec oupled fr om the t emp erature field (no t emp erature-dep enden t properties or buo yancy forces), you c an usually retain the default v alue of 1.0. 13.2.2.2. Under -Relaxation of Temp eratur e When the E nthalp y Equation is S olved When the en thalp y form of the ener gy equa tion is solv ed (tha t is, when y ou ar e using the non-adia- batic non-pr emix ed c ombustion mo del), ANSY S Fluen t also under-r elax es the t emp erature, updating the t emp erature by only a fr action of the change tha t would r esult fr om the change in the (under- relax ed) en thalp y values .This sec ond le vel of under-r elaxa tion c an b e used t o go od ad vantage when you w ould lik e to let the en thalp y field change r apidly , but the t emp erature response (and its eff ect on fluid pr operties) t o lag . ANSY S Fluen t uses a default setting of 1.0 f or the under-r elaxa tion on temp erature and y ou c an mo dify this setting using the Solution C ontrols task page . Solution → Controls Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1470Modeling H eat Transf er13.2.2.3. Disabling the Sp ecies D iffusion Term If you ar e solving f or sp ecies tr ansp ort using the pr essur e-based solv er and y ou enc oun ter convergenc e difficulties , you ma y want to consider disabling the Diffusion E nergy Sour ce option in the Species Model dialo g box. Setup → Models → Species Edit... When this option is disabled , ANSY S Fluen t will neglec t the eff ects of sp ecies diffusion on the ener gy equa tion. Note tha t sp ecies diffusion eff ects ar e alw ays included when the densit y-based solv er is used . 13.2.2.4. Step-b y-Step S olutions Often the most efficien t str ategy for pr edic ting hea t transf er is t o comput e an isother mal flo w first and then add the c alcula tion of the ener gy equa tion. The pr ocedur e diff ers sligh tly, dep ending on whether or not the flo w and hea t transf er ar e coupled . 13.2.2.4.1. Decoupled F low and H eat Transfer C alculations If your flo w and hea t transf er ar e dec oupled (no t emp erature-dep enden t properties or buo yancy forces), you c an first solv e the isother mal flo w (ener gy equa tion tur ned off ) to yield a c onverged flow-field solution and then solv e the ener gy transp ort equa tion alone . Imp ortant Since the densit y-based solv er alw ays solv es the flo w and ener gy equa tions t ogether , the procedur e for solving f or ener gy alone applies t o the pr essur e-based solv er, only . You c an t emp orarily disable the flo w equa tions or the ener gy equa tion b y deselec ting them in the Equa tions dialo g box: Solution → Controls Equa tions ... You c an also disable the ener gy equa tion: Setup → Models → Energy Off 13.2.2.4.2. Coupled F low and H eat Transfer C alculations If the flo w and hea t transf er ar e coupled (tha t is, your mo del includes t emp erature-dep enden t properties or buo yancy forces), you c an first solv e the flo w equa tions b efore enabling ener gy. Onc e you ha ve a c onverged flo w-field solution, you c an enable ener gy and solv e the flo w and ener gy equa tions simultaneously t o complet e the hea t transf er simula tion. 13.2.2.5. Specifying a S olid Time st ep For tr ansien t conjuga te hea t transf er (CHT ) problems , par ticular ly those with c ombustion, the dominan t time-sc ales in the fluid and solid z ones ar e of ten quit e diff erent. In most c ases , it is desir able t o ha ve 1471Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling C onduc tive and C onvective Heat Transf era lar ger time st ep in solid z ones , while main taining a smaller time st ep in fluid z ones .This will incr ease the sp eed a t which the solid hea t transf er reaches st eady-sta te without c ompr omising the solution accur acy of the fluid flo w. You c an sp ecify a solid time st ep on the Run C alcula tion task page: Solution → Run C alcula tion Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1472Modeling H eat Transf erFigur e 13.3: The R un C alcula tion Task P age S howing S olid Time S tep 1.Under Options , selec t Solid Time S tep. 2.Use the default Automa tic time st ep or selec t User S pecified to en ter your o wn time st ep. 1473Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling C onduc tive and C onvective Heat Transf er13.2.2.5.1. Automatic Time St ep C alculation The default Automa tic time st ep is c alcula ted b y ANSY S Fluen t using the f ollowing f ormula: (13.1) wher e, • is the r epresen tative length sc ale and is c alcula ted as . • is , the r epresen tative velocity scale, wher e is the c onduc tivit y, is the densit y, and is the specific hea t capacit y of the solid . The c alcula tion f or results in an appr oxima tion f or the solid time st ep which migh t aide in the solution r unning mor e efficien tly. It should b e not ed, however, tha t this is only an engineer ing appr oxima tion as ther e is no gener al w ay to calcula te a meaning ful length sc ale f or an arbitr ary geometr y. 13.2.3. Postpr ocessing H eat Transf er Q uan tities For inf ormation ab out p ostpr ocessing hea t transf er quan tities , see the f ollowing sec tions: 13.2.3.1. Available Variables f or P ostpr ocessing 13.2.3.2. Definition of En thalp y and Ener gy in R eports and D ispla ys 13.2.3.3. Reporting H eat Transf er Through B oundar ies 13.2.3.4. Reporting H eat Transf er Through a Sur face 13.2.3.5. Reporting A veraged H eat Transf er C oefficien ts 13.2.3.6. Exp orting H eat Flux D ata 13.2.3.1. Available Variables for P ostpr ocessing ANSY S Fluen t provides r eporting options f or simula tions in volving hea t transf er.You c an gener ate graphic al plots or r eports of the v ariables list ed under the Temp erature... or Wall F luxes... categor y. See Field F unction D efinitions (p.2959 ) for the list of a vailable v ariables and their definitions . 13.2.3.2. Definition of E nthalp y and E ner gy in R eports and D ispla ys The r eported en thalp y values ma y be diff erent between the pr essur e-based and densit y-based solv er dep ending on the pr operties of the w orking fluid , compr essible , incompr essible , ideal gas , etc. For details , see the discussion of en thalp y in The Ener gy Equa tion in chapt er 5, Heat Transf er of the Theor y Guide . 13.2.3.3. Reporting H eat Transfer Through B oundaries You c an use the Flux Rep orts dialo g box to comput e the hea t transf er thr ough each b oundar y of the domain, or t o sum the hea t transf er thr ough all b oundar ies t o check the hea t balanc e. Results → Rep orts → Fluxes Edit... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1474Modeling H eat Transf erIt is r ecommended tha t you p erform a hea t balanc e check t o ensur e tha t your solution is tr uly c on- verged . Note For the C omp osition PDF Transp ort mo del, the Flux Rep orts dialo g box reports the Total Heat Transf er R ate and Total S ensible H eat Transf er R ate only f or the Lagr angian phase solution, which do es not alw ays guar antee o verall mass c onser vation due t o the na ture of the discr ete phase mo del. To check the balanc e of hea t transf er rates tha t are based on the c ontinuous phase c omputa tion, you should use the Surface In tegrals dialo g box to create a r eport for the Flow R ate of Enthalp y (Temp erature categor y). (See Reporting Heat Transf er Through a Sur face (p.1475 ) for details .) 13.2.3.4. Reporting H eat Transfer Through a S urface You c an use the Surface In tegrals dialo g box to comput e the hea t transf er thr ough an y boundar y or an y sur face created using the metho ds descr ibed in Creating Sur faces and C ell R egist ers f or D is- playing and R eporting D ata (p.2727 ). Results → Rep orts → Surface In tegrals Edit... To report the mass flo w rate of en thalp y (13.2) choose Flow R ate for the Rep ort Type in the Surface In tegrals dialo g box, selec t Enthalp y (in the Temp erature... categor y) as the Field Variable , and selec t the sur face(s) on which t o in tegrate. 13.2.3.5. Reporting A veraged H eat Transfer C oefficients The Surface In tegrals dialo g box can also b e used t o gener ate a r eport of a veraged hea t transf er coefficien t on a sur face ( ). Results → Rep orts → Surface In tegrals Edit... In the Surface In tegrals dialo g box, cho ose Area-W eigh ted A verage for Rep ort Type, selec t Surface Heat Transf er C oef. (in the Wall F luxes... categor y) as the Field Variable , and selec t the sur face. 13.2.3.6. Exporting H eat F lux D ata It is p ossible t o export hea t flux da ta on w all z ones (including r adia tion) t o a gener ic file tha t you c an examine or use in an e xternal pr ogram. To sa ve a hea t flux file , you will use the custom-heat- flux text command . file → export → custom-heat-flux Heat transf er da ta will b e exported in the f ollowing fr ee f ormat for each fac e zone tha t you selec t for export: zone-name nfaces x_f y_f z_f A Q T_w T_c HTC 1475Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling C onduc tive and C onvective Heat Transf er . . . Each blo ck of da ta star ts with the name of the fac e zone (zone-name ) and the numb er of fac es in the z one (nfaces ). Next ther e is a line f or each fac e (tha t is,nfaces lines), each c ontaining the comp onen ts of the fac e centroid (x_f ,y_f , and , in 3D ,z_f ), the fac e ar ea (A), the hea t transf er rate (Q), the fac e temp erature (T_w ), the adjac ent cell t emp erature (T_c ), and the hea t transf er coefficien t (HTC ). If the hea t transf er coefficien t is c alcula ted based on w all func tion ( Equa tion 42.57 (p.3037 )), then is the c onvective hea t transf er rate. Other wise , will b e the t otal hea t transf er rate, including radia tion hea t transf er. 13.2.4. Natural C onvection and Buo yanc y-D riven F lows When hea t is added t o a fluid and the fluid densit y varies with t emp erature, a flo w can b e induc ed due t o the f orce of gr avity ac ting on the densit y variations . Such buo yancy-dr iven flo ws are termed natural-convection (or mix ed-c onvection) flo ws and c an b e mo deled b y ANSY S Fluen t. For mor e inf ormation ab out the theor y behind na tural convection and buo yancy-dr iven flo ws, see Natural C onvection and B uoyancy-Driven F lows Theor y in the Theor y Guide . 13.2.4.1. Mo deling N atur al C onvection in a C losed D omain When y ou mo del na tural convection inside a closed domain, the solution will dep end on the mass inside the domain. Since this mass will not b e known unless the densit y is k nown, you must mo del the flo w in one of the f ollowing w ays: •Perform a tr ansien t calcula tion. In this appr oach, the initial densit y will b e comput ed fr om the initial pressur e and t emp erature, so the initial mass is k nown. As the solution pr ogresses o ver time , this mass will b e pr operly conser ved. If the t emp erature diff erences in y our domain ar e lar ge, you must f ollow this appr oach. •Perform a st eady-sta te calcula tion using the B oussinesq mo del (descr ibed in The B oussinesq M odel (p.1476 )). In this appr oach, you will sp ecify a c onstan t densit y, so the mass is pr operly sp ecified .This appr oach is valid only if the t emp erature diff erences in the domain ar e small. If not , you use the tr ansien t appr oach. Imp ortant For a closed domain, you c an use the incompr essible ideal gas la w only with a fixed oper- ating pr essur e. It cannot be used with a floa ting op erating pr essur e.You c an use the compr essible ideal gas la w with either floating or fixed operating pr essur e. See Floating Op erating P ressur e (p.1221 ) for mor e inf ormation ab out the floa ting op erating pr essur e option. 13.2.4.2. The B oussinesq Mo del For man y na tural-convection flo ws, you c an get fast er convergenc e with the B oussinesq mo del than you c an get b y setting up the pr oblem with fluid densit y as a func tion of t emp erature.This mo del treats densit y as a c onstan t value in all solv ed equa tions , except f or the buo yancy term in the mo- men tum equa tion: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1476Modeling H eat Transf er(13.3) wher e is the (c onstan t) densit y of the flo w, is the op erating t emp erature, and is the ther mal expansion c oefficien t.Equa tion 13.3 (p.1477 ) is obtained b y using the B oussinesq appr oxima tion to elimina te from the buo yancy term.This appr oxima tion is accur ate as long as changes in ac tual densit y are small; specific ally, the B oussinesq appr oxima tion is v alid when . 13.2.4.3. Limitations of the B oussinesq Mo del The B oussinesq mo del should not b e used if the t emp erature diff erences in the domain ar e lar ge. In addition, it c annot b e used with sp ecies c alcula tions , combustion, or r eacting flo ws. 13.2.4.4. Steps in S olving Buo yanc y-Driven F low P roblems The pr ocedur e for including buo yancy forces in the simula tion of mix ed or na tural convection flo ws is descr ibed b elow. 1.To ac tivate the c alcula tion of hea t transf er, enable the ener gy equa tion b y right-click ing Energy in the tree (under Setup/M odels ) and click ing On in the menu tha t op ens ( Figur e 13.1: Enabling the Ener gy Equa tion (p.1468 )). Setup → Models → Energy On 2.Define the op erating c onditions in the Operating C onditions dialo g box (Figur e 13.4: The Op erating Conditions D ialog Box (p.1478 )). Setup → Cell Z one C onditions → Operating C onditions ... 1477Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling C onduc tive and C onvective Heat Transf erFigur e 13.4: The Op erating C onditions D ialo g Box a.Enable the Gravity option under Gravity. b.Enter the appr opriate values in the X,Y, and (f or 3D) Z fields f or Gravita tional A cceler ation for each Cartesian c oordina te dir ection. (Note tha t the default gr avitational acc eleration in ANSY S Fluen t is zero.) c.If you ar e using the inc ompr essible ideal gas la w, check tha t the Operating P ressur e is set t o an appr opriate (nonz ero) value . d.Depending on whether or not y ou use the B oussinesq appr oxima tion, specify the appr opriate par a- met ers descr ibed b elow: •If you ar e not using the B oussinesq mo del, the inputs ar e as f ollows: i.If nec essar y, enable the Specified Op erating D ensit y option in the Operating C onditions dialo g box, and en ter a v alue f or the Operating D ensit y. See b elow for details . ii.Define the fluid densit y as a func tion of t emp erature as descr ibed in Defining P roperties U sing Temp erature-Dependen t Functions (p.1095 ) and Densit y (p.1099 ). Setup → Materials •If you ar e using the B oussinesq mo del (descr ibed in The B oussinesq M odel (p.1476 )) the inputs ar e as follows: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1478Modeling H eat Transf eri.Enter the Operating Temp erature ( in Equa tion 13.3 (p.1477 )) in the Operating C onditions dialo g box. ii.Selec t boussinesq in the dr op-do wn list f or Densit y in the Create/Edit M aterials dialo g box as descr ibed in Defining P roperties U sing Temp erature-Dependen t Functions (p.1095 ) and Densit y (p.1099 ), and en ter a c onstan t value . iii.Also in the Create/Edit M aterials dialo g box, enter an appr opriate value f or the Thermal E x- pansion C oefficien t ( in Equa tion 13.3 (p.1477 )) for the fluid ma terial. Note tha t if y our mo del in volves multiple fluid ma terials y ou c an cho ose whether or not t o use the B oussinesq mo del f or each ma terial. As a r esult , you ma y ha ve some ma terials using the B oussinesq mo del and others not. In such c ases , you will need t o set all the par amet ers descr ibed ab ove in this st ep. 3.Define the b oundar y conditions .The b oundar y condition dialo g boxes c an b e op ened b y right-click ing the b oundar y name in the tr ee (under Setup/B oundar y Conditions ) and click ing Edit... in the menu that op ens; alternatively, you c an op en them fr om the Boundar y Conditions task page: Setup → Boundar y Conditions The b oundar y pr essur es tha t you sp ecify a t pressur e inlet and outlet b oundar ies ar e the r edefined pressur es as giv en b y Equa tion 13.4 (p.1479 ). In gener al you should en ter equal pr essur es, , at the inlet and e xit b oundar ies of y our ANSY S Fluen t mo del if ther e ar e no e xternally imp osed pressur e gr adien ts. 4.Set the par amet ers tha t control the solution, using the Solution M etho ds task page . Solution → Metho ds a.Selec t Body Force Weigh ted or Second Or der in the dr op-do wn list f or Pressur e under Spatial Discr etiza tion in the Solution M etho ds task page . b.If you ar e using the pr essur e-based solv er, selec ting PREST O! for Pressur e under Spatial D iscr etiz- ation is recommended . c.Add c ells near the w alls t o resolv e boundar y layers, if nec essar y. See also Solving H eat Transf er P roblems (p.1467 ) for inf ormation on setting up hea t transf er calcula tions . 13.2.4.5. Operating D ensit y When the B oussinesq appr oxima tion is not used , the op erating densit y app ears in the b ody-force term in the momen tum equa tions as .This f orm of the b ody-force term follows from the r e- definition of pr essur e in ANSY S Fluen t as (13.4) The h ydrosta tic pr essur e in a fluid a t rest is then (13.5) 1479Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling C onduc tive and C onvective Heat Transf er13.2.4.5.1. Setting the O perating D ensit y By default , ANSY S Fluen t will c omput e the op erating densit y by averaging o ver all c ells. In some cases , you ma y obtain b etter results if y ou e xplicitly sp ecify the op erating densit y inst ead of ha ving the solv er comput e it f or y ou. For e xample , if y ou ar e solving a na tural-convection pr oblem with a pressur e boundar y, it is imp ortant to understand tha t the pr essur e you ar e sp ecifying is in Equa- tion 13.4 (p.1479 ). Although y ou will k now the ac tual pr essur e , you will need t o know the op erating densit y in or der t o det ermine from .Therefore, you should e xplicitly sp ecify the op erating densit y rather than use the c omput ed a verage.The sp ecified v alue should , however, be represen tative of the a verage v alue . In some c ases the sp ecific ation of an op erating densit y will impr ove convergenc e behavior, rather than the ac tual r esults . For such c ases use the appr oxima te bulk densit y value as the op erating densit y and b e sur e tha t the v alue y ou cho ose is appr opriate for the char acteristic t emp erature in the domain. Note tha t if y ou ar e using the B oussinesq appr oxima tion f or all fluid ma terials, the op erating densit y does not app ear in the b ody-force term of the momen tum equa tion. Consequen tly, you need not specify it. 13.2.4.6. Solution Str ategies for Buo yanc y-Driven F lows For high-R ayleigh-numb er flo ws you ma y want to consider the solution guidelines b elow. In addition, the guidelines pr esen ted in Solution S trategies f or H eat Transf er M odeling (p.1470 ) for solving other heat transf er pr oblems c an also b e applied t o buo yancy-dr iven flo ws. No steady-sta te solution e xists for some laminar , high-R ayleigh-numb er flo ws. 13.2.4.6.1. Guidelines for S olving High-R ayleigh-Numb er F lows When y ou ar e solving a high-R ayleigh-numb er flo w ( ), you should f ollow one of the pr ocedur es outlined b elow for b est r esults . The first pr ocedur e uses a st eady-sta te appr oach: 1.Start the solution with a lo wer value of R ayleigh numb er (f or e xample , ) and r un it t o convergenc e using the first-or der scheme . 2.To change the eff ective Rayleigh numb er, change the v alue of gr avitational acc eleration (f or e xample , from 9.8 t o 0.098 t o reduc e the R ayleigh numb er b y two or ders of magnitude). 3.Use the r esulting da ta file as an initial guess f or the higher R ayleigh numb er and star t the higher-R ayleigh- numb er solution using the first-or der scheme . 4.After you obtain a solution with the first-or der scheme y ou ma y continue the c alcula tion with a higher- order scheme . The sec ond pr ocedur e uses a time-dep enden t appr oach t o obtain a st eady-sta te solution [46] (p.4007 ): 1.Start the solution fr om a st eady-sta te solution obtained f or the same or a lo wer R ayleigh numb er. 2.Estima te the time c onstan t as [10] (p.4005 ) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1480Modeling H eat Transf er(13.6) wher e and are the length and v elocity sc ales , respectively. Use a time st ep such tha t (13.7) Using a lar ger time st ep ma y lead t o div ergenc e. 3.After oscilla tions with a t ypic al frequenc y of 0.05–0.09 ha ve dec ayed, the solution r eaches st eady- state. Note tha t is the time c onstan t estima ted in Equa tion 13.6 (p.1481 ) and is the oscilla tion fr equenc y in Hz. In gener al this solution pr ocess ma y tak e as man y as 5000 time st eps t o reach st eady-sta te. 13.2.4.7. Postpr ocessing Buo yanc y-Driven F lows The p ostpr ocessing r eports of in terest f or buo yancy-dr iven flo ws are the same as f or other hea t transf er calcula tions . See Postpr ocessing H eat Transf er Q uan tities (p.1474 ) for details . 13.2.5. Shell C onduc tion C onsider ations For inf ormation ab out shell c onduc tion c onsider ations , see the f ollowing sec tions: 13.2.5.1. Introduction 13.2.5.2. Physical Treatmen t 13.2.5.3. Limita tions of S hell C onduc tion Walls 13.2.5.4. Managing S hell C onduc tion Walls 13.2.5.5. Initializing S hells 13.2.5.6. Locking the Temp erature for Shells 13.2.5.7. Postpr ocessing S hells 13.2.5.1. Intr oduc tion By default , ANSY S Fluen t treats w alls as ha ving z ero-thick ness and pr esen ting no ther mal r esistanc e to hea t transf er acr oss them. If a thick ness is sp ecified f or a w all (ther eby mak ing it a thin w all, as descr ibed in Thin-W all Thermal R esistanc e Paramet ers (p.986)) then the appr opriate ther mal r esistanc e across the w all thick ness is imp osed , although c onduc tion is c onsider ed in the w all in the nor mal direction only .There ar e applic ations , however, wher e conduc tion in the planar dir ections of the w all is also imp ortant. For these applic ations , you ha ve two options: you c an either mesh the thick ness , or y ou c an use the shell c onduc tion appr oach. Shell c onduc tion c an b e used t o mo del one or mor e layers of w all c ells without the need t o mesh the w all thick ness in a pr eprocessor .When the shell conduc tion appr oach is utiliz ed, you ha ve the abilit y to easily swit ch on and off c onjuga te hea t transf er on an y wall. If you cr eate a shell—either b y enabling Shell C onduc tion in an individual Wall dialo g box (as descr ibed in Shell C onduc tion (p.989)) or b y defining multiple w alls as shell c onduc tion zones using the Shell C onduc tion M anager dialo g box (as descr ibed in Managing S hell C onduc tion Walls (p.1484 ))—and define the settings f or the shell la yer(s) using the Shell C onduc tion L ayers dialo g box, then ANSY S Fluen t will aut oma tically gr ow the sp ecified la yers of c ells.The c ells tha t are gr own will b e either pr ism c ells or he x cells, dep ending on the t ype of fac e mesh tha t is utiliz ed; at no p oint are the c ells visible in the displa yed mesh. Shell c onduc tion c an b e used t o acc oun t for ther mal mass in tr ansien t ther mal analy sis pr oblems (see Locking the Temp erature for S olid and S hell Z ones (p.908) for mor e inf ormation). It can also b e used 1481Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling C onduc tive and C onvective Heat Transf erfor multiple junc tions and allo ws hea t conduc tion thr ough the junc tions . Shell c onduc tion c an b e applied on b oundar y walls as w ell as t wo-sided w alls. 13.2.5.2. Physical Treatment In the c ase wher e shell c onduc tion is applied on a b oundar y wall, the or iginal sur face is r eferred t o as the “wall sur face” and is alw ays adjac ent to the fluid / solid c ells.The first time the shell mo del is enabled a t an y wall sur face, Fluen t grows the r equir ed shell z ones .These la yers ar e numb ered sequen- tially , star ting with the one closest t o the w all sur face. See Figur e 13.5: A B oundar y Wall with S hell Conduc tion (p.1482 ) for a visualiza tion of ho w the solv er tr eats shells . For the most par t, the b oundar y conditions tha t you sp ecify f or the b oundar y wall ar e applied t o the layer sur face tha t is fur thest fr om the w all sur face; only the in ternal emissivit y is applied a t the w all surface.The sides of the shell z one r equir e boundar y conditions as w ell. If the shell is c onnec ted t o another w all tha t do es not ha ve shell c onduc tion enabled , the shell side will tak e the b oundar y con- dition of the a ttached w all.The sides will b e adiaba tic if the y are connec ted t o fac e zones tha t ha ve a boundar y condition t ype other than wall. If the a ttached w all has shell c onduc tion enabled , then the c ommon sides a t the junc tion will b e coupled . Figur e 13.5: A B oundar y Wall with S hell C onduc tion The la yers of c ells gr own f or two-sided w alls c an b e visualiz ed in a similar w ay to Figur e 13.5: A Boundar y Wall with S hell C onduc tion (p.1482 ), except tha t the la yer sur face tha t is fur thest fr om the wall sur face is also adjac ent to a shado w w all (which is then adjac ent to the other fluid / solid z one). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1482Modeling H eat Transf erFigur e 13.6: A Two-Sided Wall with S hell C onduc tion 13.2.5.3. Limitations of Shell C onduc tion Walls The f ollowing is a list of limita tions f or the shell c onduc tion mo del: •Shells c annot b e created on non-c onformal in terfaces, including mapp ed in terfaces. •Shell c onduc tion c annot b e used on mo ving w all z ones . •Shell c onduc tion c annot b e used with FMG initializa tion. •Shell c onduc tion is not a vailable when the w all is set up t o receive ther mal da ta via sy stem c oupling . •Shell c onduc tion is not a vailable f or 2D . •Shell c onduc tion is a vailable only when the pr essur e-based solv er is used . •Shell c onduc ting w alls c annot b e split or mer ged . If you need t o split or mer ge a shell c onduc ting w all, you will need t o tur n off the Shell C onduc tion option f or the w all (in the Wall dialo g box), perform the split or mer ge op eration, and then enable Shell C onduc tion for the new w all z ones . •The shell c onduc tion mo del c annot b e used on a w all z one tha t has under gone hanging no de adaption. If you w ant to perform such adaption elsewher e in the c omputa tional domain, be sur e to use a b oolean operation in an adaption e xpression t o exclude a r egist er containing the shell c onduc ting w alls. For e xample , NOT(region_0) .Refer to Adapting the Mesh (p.2705 ) for additional inf ormation on adapting the mesh . •Fluxes a t the ends of a shell c onduc ting w all ar e not included in hea t balanc e reports.These flux es ar e accoun ted f or correctly in the ANSY S Fluen t solution, but ar e not list ed in the flux r eport. •The junc tion of a w all with shell c onduc tion enabled and a non-c onformal c oupled w all is not supp orted. Such a junc tion will not b e ther mally c onnec ted, tha t is, ther e will b e no hea t transf er b etween the shell and the mesh in terface wall. •When r unning the par allel solv er with the shell c onduc tion mo del, not e tha t coupled w alls ar e enc apsula ted. If you enc oun ter pr oblems with the par titioning of the mesh, you c an tr y changing the enc apsula tion 1483Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling C onduc tive and C onvective Heat Transf ermetho d to see if tha t resolv es the pr oblem (see Troublesho oting (p.3093 ) for this and other tr oublesho oting options). •Shells with a shar p bend ma y yield non-ph ysical temp erature fields when using G reen-G auss N ode B ased gradien ts.This applies t o an y angle (acut e or obtuse) with the eff ect worsening as the angle appr oaches 90 degr ees.To resolv e the issue , you should c onsider br eaking the shar p angled shells in to multiple shells or, in the e vent tha t this c annot b e done , enabling Warped F ace Gradien t Correction. 13.2.5.4. Managing Shell C onduc tion Walls The Shell C onduc tion M anager dialo g box pr ovides a c onvenien t way for y ou t o manage , define , and displa y multiple shell c onduc tion z ones .You c an •displa y an y wall z one •enable or disable shell c onduc tion f or a w all •define the settings f or shell c onduc tion w alls or la yers, such as thick ness , material, and hea t gener ation rate •enable sa ving shell z ones t o case files . Note tha t you c an still enable shell c onduc tion f or a w all and define the r elated settings using the Wall dialo g box, as descr ibed in Shell C onduc tion (p.989). However, the Shell C onduc tion M anager dialo g box pr ovides y ou with an alt ernative to do such ac tivities fr om a single dialo g box for all the walls, inst ead of visiting the individual Wall boundar y condition dialo g boxes. Physics → Model S pecific → Shell C onduc tion... Figur e 13.7: The S hell C onduc tion M anager D ialo g Box Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1484Modeling H eat Transf erTo manage shell c onduc tion using the Shell C onduc tion M anager dialo g box, perform the f ollowing steps: 1.(optional) I f you ha ve pr eviously gener ated a CSV file tha t contains shell c onduc tion settings f or the layers of the w alls, you c an r ead it b y click ing Read ... at the b ottom of the Shell C onduc tion M anager dialo g box and using the dialo g box tha t op ens; other wise , you should pr oceed t o the st eps tha t follow. Using a CSV file c an b e helpful when y ou ha ve a lar ge numb er of la yers and w alls. It is not nec essar y to cr eate the CSV file fr om nothing , as y ou c an cr eate a simplified CSV file with sample v alues using the Write... butt on (as descr ibed in st ep 5.), and then r evise the settings using a spr eadsheet program. See Shell C onduc tion S ettings F ile F ormat (p.3987 ) for details ab out the f ormat of the CSV file . 2.Use the and butt ons t o mo ve the selec ted z ones fr om one list t o another , and ther eby define whether the y are shells . Zones with shell c onduc tion enabled ar e list ed under Shell C onduc tion Z ones and those without shell c onduc tion ar e list ed under Wall Z ones . In essenc e, the butt on disables shell c onduc tion and the butt on enables shell c onduc tion. 3.Enable sa ving shell z ones t o case file is enabled b y default so tha t Fluen t aut oma tically wr ites shell zones in to .cas files .When a c ase with shell z ones is r ead back in to Fluen t, the shell z ones will not need to be recreated. 4.Click the Displa y Zones butt on t o displa y the selec ted w alls in the gr aphics windo w. Note tha t you c an selec t walls with or without shell c onduc tion. The z ones will b e displa yed with diff erent colors dep ending on the option selec ted in the Mesh C olors dialo g box, which is acc essible fr om the Mesh D ispla y dialo g box. 5.Define settings f or all of the shells b y performing the f ollowing st eps: a.Selec t walls fr om the Shell C onduc tion Z ones for which y ou w ant to define the same settings . b.Click the Settings ... butt on t o op en the Shell C onduc tion L ayers dialo g box (Figur e 13.8: Shell Conduc tion La yers D ialog Box (p.1486 )).There you c an sp ecify the numb er of la yers, and then define the thick ness , material, and hea t gener ation r ate for each la yer. Note tha t you ha ve the option of defining the hea t gener ation r ate using a user-defined func tion (UDF) tha t utiliz es the DEFINE_PROFILE macr o; for mor e inf ormation on cr eating and using user-defined func tions , see the Fluen t Customiza tion M anual . Imp ortant You must sp ecify a nonz ero-thick ness f or e very layer. 1485Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling C onduc tive and C onvective Heat Transf erFigur e 13.8: Shell C onduc tion L ayers D ialo g Box c.Click OK to sa ve your settings f or the selec ted w alls and close the Shell C onduc tion L ayers dialo g box. 6.If you w ant to sa ve all of the settings y ou sp ecified using the Shell C onduc tion M anager dialo g box as a CSV file , click Write... and sp ecify a name in the dialo g box tha t op ens.You c an edit the shell c onduc tion settings in this CSV file using a spr eadsheet pr ogram, and then r ead it in this or a separ ate case file , as descr ibed in st ep 1. Note tha t inf ormation will not b e wr itten for an y wall tha t defines the hea t gener ation rate using a UDF . Note tha t you ha ve the option of disabling shell c onduc tion in e very wall with a single ac tion, by using the f ollowing t ext command .This c apabilit y is a vailable in b oth ser ial and par allel mo de. define → boundary-conditions → modify-zones → delete-all-shells 13.2.5.5. Initializing Shells Shell z ones c an b e pa tched using the Patch dialo g box, as descr ibed in Patching Values in S elec ted Cells (p.2607 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1486Modeling H eat Transf erSolution → Initializa tion Patch... 13.2.5.6. Locking the Temp eratur e for Shells You c an lo ck (or “freeze”) the t emp erature values f or all the c ells in shells and solid z ones (including those t o which y ou ha ve a ho oked an ener gy sour ce thr ough a UDF) b y using the solve/set/lock- solid-temperature? text command , as descr ibed in Locking the Temp erature for S olid and S hell Zones (p.908). 13.2.5.7. Postpr ocessing Shells In or der t o facilita te the p ostpr ocessing of shells , sur faces (r eferred t o as “shell sur faces”) ar e created at the in terface of adjac ent layers, as w ell as a t the la yer sur face tha t is fur thest fr om the w all sur face. Note tha t shell sur faces ar e not cr eated on the sides of the shell z ones or in the in terior of the la yers. The shell sur faces c an then b e selec ted fr om the Surfaces list a vailable in a v ariety of dialo g boxes (for e xample , the Contours dialo g box, the Surface Rep ort Definition dialo g box, and the Solution XY Plot dialo g box) in the same w ay as the sur faces for the w all and (f or two-sided w alls) the shado w wall.When visualiz ed in the gr aphics displa y windo w, these shell sur faces will b e coinciden t with the wall the y are asso ciated with. The default naming c onvention f or these shell sur faces is < wall_name >-:, wher e: • is the name of the w all on which the la yers ha ve been gr own. • is the r ank of the la yer on the c0 side of the in terface (tha t is, the la yer closest t o the w all sur face). • is the r ank of the la yer on the c1 side of the in terface (tha t is, the la yer fur thest fr om the w all sur face). Note tha t the la yer sur face tha t is fur thest fr om the w all sur face do es not ha ve a la yer on the c1 side , and so a diff erent convention is used: for b oundar y walls, is set t o external; for two-sided w alls, is set t o the name of the fluid / solid adjac ent to the shado w w all. You ha ve the abilit y to rename the shell sur faces, if y ou w ant.The f ollowing figur es illustr ate the default naming c onvention, wher e the w all/shado w sur faces ar e displa yed in r ed and the shell sur faces ar e displa yed in black. Figur e 13.9: Shell S urface Names f or a B oundar y Wall 1487Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling C onduc tive and C onvective Heat Transf erFigur e 13.10: Shell S urface Names f or a Two-Sided Wall You c an use the w alls, shado w w alls, and shell sur faces to displa y the t emp erature of the in terfaces and adjac ent cells.The Temp erature... categor y pr ovides t wo options: the t emp erature of the c ell on the c0 side of the sur face is st ored as Static Temp erature; and the t emp erature of the sur face itself is st ored as Wall Temp erature. If a mor e detailed analy sis of the solid z one and sur faces is r equir ed, then y ou should c onsider cr eating la yers of solid c ells in y our meshing applic ation. The f ollowing e xamples illustr ate ho w to postpr ocess the sur faces sho wn in Figur e 13.9: Shell Sur face Names f or a B oundar y Wall (p.1487 ): •The Static Temp erature and Wall Temp erature of Bwall will pr ovide the t emp erature of the fluid c ells adjac ent to Bwall and the t emp erature of the Bwall surface itself , respectively. •The Static Temp erature and Wall Temp erature of Bwall-1:2 will pr ovide the t emp erature of the c ells of Layer 1 and the t emp erature of the in terface between Layer 1 and Layer 2 (tha t is, the Bwall-1:2 shell surface), respectively. •The Static Temp erature and Wall Temp erature of Bwall-3:e xternal will pr ovide the t emp erature of the cells of Layer 3 and the t emp erature of the la yer sur face tha t is fur thest fr om the w all sur face (tha t is, the Bwall-3:e xternal shell sur face), respectively. The f ollowing e xamples illustr ate ho w to postpr ocess the sur faces sho wn in Figur e 13.10: Shell Sur face Names f or a Two-Sided Wall (p.1488 ): •The Static Temp erature and Wall Temp erature of 2Swall-4:air will pr ovide the t emp erature of the c ells of Layer 4 and the t emp erature of the in terface between Layer 4 and the shado w w all (tha t is, the 2Swall- 4:air shell sur face), respectively. •The Static Temp erature and Wall Temp erature of 2Swall-shado w will pr ovide the t emp erature of the air c ells adjac ent to 2Swall-shado w and the t emp erature of the shado w w all, respectively. When p ostpr ocessing shells , not e the f ollowing limita tions: •You should not enable Node Values when p ostpr ocessing an y sur faces asso ciated with shells (tha t is, the wall, shado w w all, or shell sur faces).The la yers shar e no des a t the edges , and thus the a veraging a t such nodes is er roneous . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1488Modeling H eat Transf er•You c annot p ostpr ocess shells in ANSY S CFD-P ost, as shell sur faces ar e not supp orted. 13.3. Modeling R adia tion Information ab out r adia tion mo deling is pr esen ted in the f ollowing sec tions: 13.3.1. Using the R adia tion M odels 13.3.2. Setting U p the P-1 M odel with N on-G ray Radia tion 13.3.3. Setting U p the DTRM 13.3.4. Setting U p the S2S M odel 13.3.5. Setting U p the DO M odel 13.3.6. Setting U p the MC M odel 13.3.7. Defining M aterial P roperties f or R adia tion 13.3.8. Defining B oundar y Conditions f or R adia tion 13.3.9. Solution S trategies f or R adia tion M odeling 13.3.10. Postpr ocessing R adia tion Q uantities 13.3.11. Solar L oad M odel For theor etical inf ormation ab out the r adia tion mo dels in ANSY S Fluen t, refer to Modeling R adia tion in the Theor y Guide . 13.3.1. Using the R adia tion M odels The pr ocedur e for setting up and solving a r adia tion pr oblem is outlined b elow, and descr ibed in detail in referenced sec tions . Steps tha t are relevant only f or a par ticular r adia tion mo del ar e not ed as such. The st eps tha t are pertinen t to radia tion mo deling , are sho wn her e. For inf ormation ab out inputs r elated to other mo dels tha t you ar e using in c onjunc tion with r adia tion, see the appr opriate sec tions f or those mo dels . 1.Enable r adia tive hea t transf er b y selec ting a r adia tion mo del ( Rosseland ,P1,Discr ete Transf er (DTRM) , Surface to Surface (S2S) ,Discr ete Or dina tes, or Monte Carlo (MC) ) under Model in the Radia tion Model dialo g box (Figur e 13.11: The R adia tion M odel D ialog Box (DO M odel) (p.1490 )). Setup → Models → Radia tion Edit... 1489Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling R adia tionFigur e 13.11: The R adia tion M odel D ialo g Box (DO M odel) Imp ortant The Rosseland mo del c an b e used only with the pr essur e-based solv er. Note tha t when the P-1, the DTRM, the S2S, DO , or MC mo del is enabled , the Radia tion M odel dialo g box expands t o sho w additional par amet ers.These par amet ers will not app ear if y ou selec t the R osseland mo del. If you ar e running a 3D c ase, you will ha ve the added option of using the solar load mo del. The solar load options will b e displa yed in the dialo g box, below the r adia tion model settings . When the r adia tion mo del is ac tive, the r adia tion flux es will b e included in the solution of the ener gy equa tion a t each it eration. If you set up a pr oblem with the r adia tion mo del tur ned on, and y ou then decide t o tur n it off c omplet ely, you must selec t the Off butt on in the Radia tion M odel dialo g box. Note tha t when y ou enable a r adia tion mo del, ANSY S Fluen t will aut oma tically enable the ener gy equa tion so tha t step is not needed . 2.Set the appr opriate radia tion par amet ers. a.If you ar e mo deling non-gr ay radia tion using the P-1 mo del, define the non-gr ay radia tion par amet ers as descr ibed in Setting U p the P-1 M odel with N on-G ray Radia tion (p.1491 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1490Modeling H eat Transf erb.If you ar e using the DTRM, define the r ay tracing as descr ibed in Setting U p the DTRM (p.1492 ). c.If you ar e using the S2S mo del, define the sur face clust ers and view fac tors settings and c omput e or read the view fac tors as descr ibed in Setting U p the S2S M odel (p.1495 ). d.If you ar e using the DO mo del, cho ose DO/E nergy Coupling if desir ed, define the angular discr etiza tion as descr ibed in Setting U p the DO M odel (p.1509 ) and , if relevant, define the non-gr ay radia tion par a- met ers as descr ibed in Defining N on-G ray Radia tion f or the DO M odel (p.1510 ). e.If you ar e using the MC mo del, specify the Target N umb er of Hist ories as descr ibed in Setting U p the MC M odel (p.1512 ) and , if relevant, similar t o when using the DO mo del, define the non-gr ay radia tion paramet ers as descr ibed in Defining N on-G ray Radia tion f or the DO M odel (p.1510 ). 3.Define the ma terial pr operties as descr ibed in Defining M aterial P roperties f or R adia tion (p.1513 ). 4.Define the b oundar y conditions as descr ibed in Defining B oundar y Conditions f or R adia tion (p.1514 ). If your mo del c ontains a semi-tr anspar ent medium, see the inf ormation b elow on setting up semi-tr anspar ent media. 5.Set the par amet ers tha t control the solution (DTRM, DO, MC, S2S, and P-1 only) as descr ibed in Solution Strategies f or R adia tion M odeling (p.1531 ). 6.Run the solution as descr ibed in Running the C alcula tion (p.1535 ). 7.Postpr ocess the r esults as descr ibed in Postpr ocessing R adia tion Q uan tities (p.1536 ). 13.3.2. Setting U p the P-1 M odel with N on-G ray Radia tion If you w ant to mo del non-gr ay radia tion using the P-1 mo del, you c an sp ecify the Numb er of B ands under Non-G ray M odel in the e xpanded Radia tion M odel dialo g box (Figur e 13.12: The R adia tion Model D ialog Box (N on-G ray P-1 M odel) (p.1492 )). By default , the Numb er of B ands is set t o zero, indic- ating tha t only gr ay radia tion will b e mo deled . Because the c ost of c omputa tion incr eases dir ectly with the numb er of bands , you should tr y to minimiz e the numb er of bands used .When a nonz ero Numb er of B ands is sp ecified , the Radia tion M odel dialo g box will e xpand onc e again t o sho w the Wavelength Intervals. For each w avelength band , you c an sp ecify a Name , as w ell as the Start and End wavelength of the band in m. Note tha t the w avelength bands ar e sp ecified f or v acuum ( ). For mor e inf orm- ation ab out non-gr ay radia tion c alcula tions , see Defining N on-G ray Radia tion f or the DO M odel (p.1510 ). 1491Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling R adia tionFigur e 13.12: The R adia tion M odel D ialo g Box (N on-G ray P-1 M odel) ANSY S Fluen t allo ws you t o use a user-defined func tion (UDF) t o mo dify the emissivit y weigh ting fac tor (which other wise defaults t o the black b ody emission fac tor obtained fr om a standar d Planck distr ibution). The emissivit y weigh ting fac tor app ears in the emission t erm of the radia tive transf er equa tion f or the non-gr ay mo del, as sho wn in Equa tion 5.25 in the Theor y Guide . For mor e inf ormation, see the Fluen t Customiza tion M anual . 13.3.3. Setting U p the DTRM For inf ormation ab out setting up the DTRM, see the f ollowing sec tions: 13.3.3.1. Defining the R ays 13.3.3.2. Controlling the C lusters 13.3.3.3. Controlling the R ays 13.3.3.4. Writing and R eading the DTRM R ay File 13.3.3.5. Displa ying the C lusters 13.3.3.1. Defining the R ays When y ou selec t the Discr ete Transf er mo del and click OK in the Radia tion M odel dialo g box, the DTRM R ays dialo g box (Figur e 13.13: The DTRM R ays Dialog Box (p.1493 )) will op en aut oma tically. If you need t o mo dify the cur rent settings la ter in the pr oblem setup or solution pr ocedur e, you c an open this dialo g box by click ing DTRM R ays... in the Physics ribbon tab ( Model S pecific group b ox). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1492Modeling H eat Transf erFigur e 13.13: The DTRM R ays Dialo g Box In this dialo g box you will set par amet ers f or and cr eate the r ays and clust ers discussed in The DTRM Equa tions in the Theor y Guide . The pr ocedur e is as f ollows: 1.To control the numb er of r adia ting sur faces and absorbing c ells, set the Cells P er Volume C lust er and Faces P er S urface Clust er. (See the e xplana tion b elow.) 2.To control the numb er of r ays being tr aced, set the numb er of Theta D ivisions and Phi D ivisions . (Guidelines ar e pr ovided b elow.) 3.When y ou click OK in the DTRM R ays dialo g box,The S elec t File D ialog Box (p.569) will op en pr ompting you f or the name of the “ray file ”. After you ha ve sp ecified the filename and chosen whether t o wr ite a binar y ray file , ANSY S Fluen t will wr ite the r ay file and then r ead it af terward. During the wr ite pr ocess the sta tus of the DTRM r ay tracing will b e reported in the ANSY S Fluen t console . For e xample: Completed 25% tracing of DTRM rays Completed 50% tracing of DTRM rays Completed 75% tracing of DTRM rays Completed 100 % tracing of DTRM rays See f ollowing sec tions f or details on DTRM R ays dialo g box inputs . Imp ortant If you c ancel the DTRM R ays dialo g box without wr iting and r eading the r ay file , the DTRM will b e disabled . 13.3.3.2. Contr olling the C lust ers Your inputs f or Cells P er Volume C lust er and Faces P er S urface Clust er will c ontrol the numb er of radia ting sur faces and absorbing c ells. By default , each is set t o 1, so the numb er of sur face clust ers (radia ting sur faces) will b e the numb er of b oundar y fac es, and the numb er of v olume clust ers (absorb- ing c ells) will b e the numb er of c ells in the domain. For small 2D pr oblems , these ar e acc eptable numb ers, but f or lar ger pr oblems y ou will w ant to reduc e the numb er of sur face and/or v olume 1493Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling R adia tionclust ers in or der t o reduc e the r ay-tracing e xpense . See Clustering in the Theor y Guide for details about clust ering. Note •Only z ones a ttached t o fluid c ell z ones ar e used f or cr eating sur face clust ers. •Faces P er S urface Clust er (FPSC) is indic ative of the ac tual r educ tion fac tor e xcept when the surfaces ar e planar .The sur face clust ering algor ithm uses other cr iteria (angle b etween fac es, and so on) t o ensur e the clust ers ar e near ly planar , so it is p ossible tha t ther e will b e no fur ther reduc tion in the t otal numb er of clust ers b eyond a c ertain v alue of FPSC. 13.3.3.3. Contr olling the R ays Your inputs f or Theta D ivisions and Phi D ivisions will c ontrol the numb er of r ays being tr aced fr om each sur face clust er (r adia ting sur face). Theta D ivisions defines the numb er of discr ete divisions in the angle used t o define the solid angle about a p oint on a sur face.The solid angle is defined as varies fr om 0 t o 90 degr ees (in the Theor y Guide ), and the default setting of 1 f or the numb er of discr ete settings implies tha t ther e will be one r ay traced fr om the sur face. Phi D ivisions defines the numb er of discr ete divisions in the angle used t o define the solid angle about a p oint on a sur face.The solid angle is defined as varies fr om 0 t o 360 degr ees ( Fig- ure 5.2: Angles θ and φ Defining the H emispher ical Solid A ngle A bout a P oint P in the Theor y Guide ). The default setting of 4 implies tha t each r ay traced fr om the sur face will b e lo cated a t a 90° angle , and in c ombina tion with the default setting f or Theta D ivisions , above, implies tha t 4 r ays will b e traced fr om each sur face control volume . In man y cases , it is r ecommended tha t you a t least double the numb er of divisions in and . 13.3.3.4. Writing and R eading the DTRM R ay File After y ou ha ve ac tivated the DTRM and defined all of the par amet ers c ontrolling the r ay tracing , you must cr eate a r ay file , which will b e read back in and used dur ing the r adia tion c alcula tion. The r ay file c ontains a descr iption of the r ay traces (f or e xample , path lengths , cells tr aversed b y each r ay). This inf ormation is st ored in the r ay file , inst ead of b eing r ecomput ed, in or der t o sp eed up the c al- cula tion pr ocess. By default , a binar y ray file will b e wr itten.You c an also cr eate text (formatted) r ay files b y tur ning off the Write Binar y Files option in The S elec t File D ialog Box (p.569). Imp ortant Do not wr ite or r ead a c ompr essed r ay file , because ANSY S Fluen t will not b e able t o acc ess the r ay tracing inf ormation pr operly fr om a c ompr essed r ay file . The r ay filename must b e sp ecified t o ANSY S Fluen t only onc e.Thereafter, the filename is st ored in your c ase file and the r ay file will b e aut oma tically r ead in to ANSY S Fluen t whene ver the c ase file is read. ANSY S Fluen t will r emind y ou tha t it is r eading the r ay file af ter it finishes r eading the r est of the c ase file b y reporting its pr ogress in the c onsole . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1494Modeling H eat Transf erNote tha t the r ay filename st ored in y our c ase file ma y not c ontain the full name of the dir ectory in which the r ay file e xists .The full dir ectory name will b e stored in the c ase file only if y ou initially r ead the r ay file thr ough the GUI (or if y ou t yped in the dir ectory name along with the filename when using the t ext interface). In the e vent tha t the full dir ectory name is absen t, the aut oma tic r eading of the ray file ma y fail (sinc e ANSY S Fluen t do es not k now in which dir ectory to lo ok f or the file), and y ou will need t o manually sp ecify the r ay file , using the File/Read/DTRM R ays... ribbon tab it em. The safest appr oaches ar e to use the GUI when y ou first r ead the r ay file or t o supply the full dir ectory name when using the t ext interface. Imp ortant You must r ecreate the r ay file whene ver y ou do an ything tha t changes the mesh, such as: •change the t ype of a b oundar y zone •adapt the mesh •scale the mesh You c an op en the DTRM R ays dialo g box dir ectly b y click ing DTRM R ays... in the Physics ribbon tab ( Model S pecific group b ox). 13.3.3.5. Displa ying the C lust ers Onc e a r ay file has b een cr eated or r ead in manually , you c an click the Displa y Clust ers butt on in the DTRM R ays dialo g box to gr aphic ally displa y the clust ers in the domain. See Displa ying R ays and Clusters f or the DTRM (p.1538 ) for additional inf ormation ab out displa ying r ays and clust ers. 13.3.4. Setting U p the S2S M odel When y ou selec t the Surface to Surface (S2S) mo del, the Radia tion M odel dialo g box will e xpand to sho w additional par amet ers (see Figur e 13.14: The R adia tion M odel D ialog Box (S2S M odel) (p.1496 )). In these additional gr oup b oxes, you will set the solution par amet ers (see S2S S olution P aramet ers (p.1534 ) for fur ther details), acc ess the view fac tors and clust ering settings , and c omput e the view fac tors f or your pr oblem or r ead pr eviously c omput ed view fac tors in to ANSY S Fluen t. 1495Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling R adia tionFigur e 13.14: The R adia tion M odel D ialo g Box (S2S M odel) The S2S r adia tion mo del is v ery expensiv e in t erms of c omputa tion eff ort and memor y requir emen ts when ther e ar e a lar ge numb er of r adia ting sur faces.You c an r educ e the numb er of r adia ting sur faces by gr ouping fac es together t o form sur face clust ers.The sur face clust er inf ormation (c oordina tes and connec tivit y of the no des, sur face clust er IDs) is used b y ANSY S Fluen t in the r adiosit y calcula tions and to comput e the view fac tors. Imp ortant •You must r ecreate the sur face clust er inf ormation whene ver you do an ything tha t changes the mesh, such as: –change the t ype of a b oundar y zone –scale the mesh Note tha t you do not need t o recalcula te view fac tors af ter shell c onduc tion a t an y wall has b een enabled or disabled (see Thermal B oundar y Conditions a t Walls (p.984) for mor e information ab out shell c onduc tion). However, enabling or disabling shell c onduc tion in the par allel v ersion of F luen t do es c ause a migr ation of c ells and henc e a change in the partition. Whene ver ther e is c ell migr ation, the pr eviously r ead view fac tor file is no longer valid, and the view fac tor file must b e read again using either the Read E xisting F ile Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1496Modeling H eat Transf erbutt on in the Radia tion M odel dialo g box or the File/Read/Vie w F actors... ribbon tab item. •ANSY S Fluen t will w arn you t o recreate the clust er/view fac tor file if a b oundar y zone has b een changed fr om a w all to an in ternal w all (or vic e versa), or if a b oundar y zone has b een mer ged , separ ated, or fused . 13.3.4.1. View F actors and C lust ering S ettings You c an use the View F actors and C lust ering dialo g box (Figur e 13.15: The View F actors and C lustering Dialog Box (p.1498 )) to define ho w the sur face clust ers ar e formed and ho w the view fac tors ar e calcu- lated f or the S2S mo del. To op en this dialo g box, click Settings ... in the View F actors and C lust ering group b ox in the Radia tion M odel D ialog Box (p.3269 ) (Figur e 13.14: The R adia tion M odel D ialog Box (S2S M odel) (p.1496 )) or use the File/W rite/Surface Clust ers... ribbon tab it em. 1497Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling R adia tionFigur e 13.15: The View F actors and C lust ering D ialo g Box 13.3.4.1.1. Forming S urface Clust ers You c an set the numb er of fac es p er sur face clust er (FPSC) f or each flo w b oundar y (tha t is, exhaust fan, inlet v ent, intake fan, outlet v ent, mass-flo w inlet , mass-flo w outlet , pressur e far-field , pressur e inlet , pressur e outlet , outflo w, and v elocity inlet b oundar y) and w all tha t is adjac ent to a fluid z one; in this w ay, you c an c ontrol the numb er of r adia ting sur faces and (if y ou selec t Clust er t o Clust er for Basis ) view fac tor sur faces. By default , the FPSC v alue is set t o everywher e, so the numb er of surface clust ers (r adia ting/view fac tor sur faces) will b e equal t o the numb er of b oundar y fac es. For small 2D pr oblems , this is an acc eptable numb er. For lar ger pr oblems , you ma y want to reduc e the numb er of sur face clust ers (tha t is, incr ease the FPSC) t o reduc e both the siz e of the view fac tor file and the memor y requir emen t. Such a r educ tion in the numb er of clust ers, however, comes a t the cost of some accur acy. Note tha t for a ther mally c oupled mesh in terface (tha t is, a fluid-fluid in terface Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1498Modeling H eat Transf erwith Coupled Wall enabled , or an in terface involving a solid z one), the FPSC is alw ays set t o 1. See Clustering in the Theor y Guide for details ab out clust ering. Imp ortant If you plan t o use the clust er to clust er basis f or the view fac tor c alcula tion, be sur e that the FPSC v alues ar e appr opriate for b oth the r adiosit y calcula tion and the view factors. Note tha t dur ing the cr eation of a clust er on a non-c onformal in terface, its par ent thr ead is tak en into the c onsider ation; it ma y happ en tha t the clust er is somewha t lar ger than its child fac e, which may lead some inaccur acy in the flux c alcula tion. The Clust ering group b ox in the View F actors and C lust ering dialo g box (Figur e 13.15: The View Factors and C lustering D ialog Box (p.1498 )) provides t wo metho ds for revising the default FPSC v alues: •manual •automa tic If you selec t Manual in the Options group b ox, you c an sp ecify an FPSC v alue f or all flo w b oundar ies in the Faces p er S urface Clust er f or F low B oundar y Zones numb er-en try box in the Manual group box. If you then click Apply t o A ll Walls, you will apply this v alue t o all w all z ones tha t are adjac ent to fluid z ones as w ell. For a w all tha t requir es a diff erent FPSC v alue (tha t is, you ma y want a lo wer value f or w alls in cr itical ar eas, and higher v alues in non-cr itical ar eas), you will need t o op en the boundar y condition dialo g box (Figur e 13.16: The Wall D ialog Box (p.1500 )) for tha t par ticular w all and mo dify the Faces P er S urface Clust er in the S2S P aramet ers group b ox of the Radia tion tab . Note tha t the Radia tion tab also allo ws you t o sp ecify whether the w all par ticipa tes in the view factor c alcula tion, as descr ibed in Specifying B oundar y Zone P articipa tion (p.1503 ). Note •Only z ones a ttached t o fluid c ell z ones ar e used f or cr eating sur face clust ers. •Faces P er S urface Clust er (FPSC) is indic ative of the ac tual r educ tion fac tor e xcept when the surfaces ar e planar .The sur face clust ering algor ithm uses other cr iteria (angle b etween fac es, and so on) t o ensur e the clust ers ar e near ly planar , so it is p ossible tha t ther e will b e no fur ther reduc tion in the t otal numb er of clust ers b eyond a c ertain v alue of FPSC. 1499Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling R adia tionFigur e 13.16: The Wall D ialo g Box Imp ortant The Faces P er S urface Clust er numb er-en try box will not b e visible in the GUI on w all boundar y zones tha t are attached t o a solid . Using the manual metho d to sp ecify the FPSC v alues f or w alls c an b ecome v ery cumb ersome if the model in volves a lar ge numb er of r adia ting fac es, which is t ypic ally the c ase in under hood mo dels . In such cir cumstanc es, it is r ecommended tha t you use the aut oma tic clust ering metho d inst ead. In this metho d, diff erent FPSC v alues ar e assigned t o the w alls aut oma tically, based on the distanc e of the w alls fr om and the FPSC v alues of the w alls tha t are defined as cr itical.The st eps y ou will need to tak e ar e as f ollows: 1.Selec t Automa tic from the Options list in the View Factors and C lust ering dialo g box. 2.For each w all tha t you deem cr itical, perform the f ollowing ac tions in the Wall dialo g box (Fig- ure 13.16: The Wall D ialog Box (p.1500 )): a.Click the Radia tion tab . b.Enter an appr opriate value f or Faces P er S urface Clust er in the S2S P aramet ers group b ox. c.Enable the Critical Z one option. d.Click OK to close the Wall dialo g box. 3.Enter the Maximum F aces p er S urface Clust er value in the View Factors and C lust ering dialo g box and click the Comput e butt on. ANSY S Fluen t will aut oma tically c alcula te and up date the Faces P er Surface Clust er values f or all Wall dialo g boxes adjac ent to fluid z ones tha t do not ha ve Critical Z one enabled , without c omputing the clust ers. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1500Modeling H eat Transf er4.You c an check the aut oma tically assigned FPSC v alues b y op ening the b oundar y condition dialo g box of an y non-cr itical w all of in terest and e xamining the v alue f or Faces P er S urface Clust er in the S2S Paramet ers group b ox of Radia tion tab .You c an manually mo dify the v alue f or Faces P er S urface Clust er as nec essar y. 13.3.4.1.1.1. Setting the Split A ngle for C lust ers Whether y ou set the FPSC v alue manually or aut oma tically, you ha ve the option of mo difying the cutoff or “split ” angle b etween adjac ent fac e nor mals f or the pur pose of c ontrolling sur face clust ering. The split angle sets the limit f or which adjac ent fac es ar e clust ered. A smaller split angle allo ws for a better represen tation of the view fac tor. By default , no sur face clust er will c ontain an y fac e tha t has a fac e nor mal gr eater than 20°.To mo dify the v alue of this par amet er, you c an use the split- angle text command: define → models → radiation → s2s-parameters → split-angle or file → write-surface-clusters → split-angle 13.3.4.1.2. Setting Up the View F actor C alculation You c an c ontrol man y asp ects of ho w the view fac tors ar e calcula ted f or y our S2S mo del: how sur faces are defined; the c omputa tional metho d and r elated par amet ers; whether sur face blo cking will b e accoun ted f or; and which b oundar y zones will par ticipa te in the c alcula tion. All of these c ontrols ar e available in the View F actors group b ox in the View F actors and C lust ering dialo g box (Fig- ure 13.15: The View F actors and C lustering D ialog Box (p.1498 )), and ar e descr ibed in the sec tions tha t follow. 13.3.4.1.2.1. Selec ting the B asis for C omputing View F actors ANSY S Fluen t allo ws two ways to define the sur faces used f or the view fac tor c alcula tion, as descr ibed in Clustering and View F actors in the Theor y Guide . If you w ant the sur faces to be the b oundar y faces of the mesh, selec t Face to Face for Basis in the View F actor group b ox of the View F actors and C lust ering dialo g box.This is the default selec tion. Alternatively, you c an selec t Clust er t o Clust er for Basis , in or der t o reduc e the c omputa tional e x- pense and st orage r equir emen ts. In this c ase, the sur faces used t o calcula te the view fac tors ar e the clust ers defined b y the settings in the Clust er group b ox of the View F actors and C lust ering dialo g box.The r educ tion in c omputa tional time will b e pr oportional t o the numb er of sur face clust ers used in the view fac tor c alcula tion. The tr ade-off s of using the clust er to clust er basis f or the c alcu- lation ar e tha t the accur acy ma y decr ease , and the f ollowing limita tions apply : •The mesh must b e 3D . •You c annot sub divide the fac es as par t of the hemicub e metho d par amet ers, which c an c ause the view factors t o be overestima ted. •Polyhedr al meshes ar e restricted t o 1 fac e per sur face clust er. •When using the clust er to clust er basis with non-c onformal in terfaces, the Faces P er S urface Clust er will b e limit ed t o one , giving no ad vantage t o the clust er to clust er basis . 1501Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling R adia tion13.3.4.1.2.2. Selec ting the Metho d for C omputing View F actors ANSY S Fluen t provides t wo metho ds for c omputing view fac tors: the r ay tracing metho d (which is selec ted b y default) and the hemicub e metho d.The f ollowing limita tions apply : •The hemicub e metho d is a vailable only f or 3D and axisymmetr ic cases . •The hemicub e metho d should not b e used when an y of the z ones ar e defined as p eriodic or symmetr y boundar ies, as these t ypes ar e not cur rently supp orted. •For the r ay tracing metho d, when r unning in distr ibut ed par allel mo de (including with M icrosof t Job Scheduler), the w orking dir ectory must b e shar ed acr oss all machines . The hemicub e metho d uses a diff erential ar ea-t o-ar ea metho d and c alcula tes the view fac tors on a row-b y-row basis .The view fac tors c alcula ted fr om the diff erential ar eas ar e summed t o pr ovide the view fac tor for the whole sur face.This metho d or igina ted fr om the use of the r adiosit y appr oach in the field of c omput er gr aphics [24] (p.4006 ). To use the hemicub e metho d to comput e the view fac tors, selec t Hemicub e from the Metho d list in the View F actors and C lust ering dialo g box. It is r ecommended tha t you use the hemicub e metho d for lar ge, comple x mo dels with f ew obstr ucting sur faces b etween the r adia ting sur faces. The hemicub e metho d is based up on thr ee assumptions ab out the geometr y of the sur faces: aliasing , visibilit y, and pr oximit y.To valida te these assumptions , you c an sp ecify thr ee diff erent hemicub e paramet ers, which c an help y ou obtain b etter accur acy in c alcula ting view fac tors. In most c ases , however, the default settings will b e sufficien t. •Aliasing—T he tr ue pr ojec tion of each visible fac e on to the hemicub e can b e accur ately acc oun ted f or by using a finit e-resolution hemicub e. As descr ibed pr eviously , the fac es ar e pr ojec ted on to a hemicub e. Because of the finit e resolution of the hemicub e, the pr ojec ted ar eas and r esulting view fac tors ma y be overestima ted or under estima ted. Aliasing eff ects can b e reduc ed b y incr easing the v alue of the Resol- ution of the hemicub e in the Paramet ers group b ox. •Visibilit y—T he visibilit y between an y two fac es do es not change . In some c ases , face has a c omplet e view of fac e from its c entroid, but some other fac e occludes much of fac e from fac e . In such a case, the hemicub e metho d will o verestima te the view fac tor b etween fac e and fac e calcula ted fr om the c entroid of fac e .This er ror can b e reduc ed b y sub dividing fac e into smaller subfac es.You c an specify the numb er of subfac es b y en tering a v alue f or Subdivisions in the Paramet ers group b ox. Note that you c annot sub divide the fac es when Clust er to Clust er is selec ted f or Basis . •Proximit y—T he distanc e between fac es is gr eat compar ed t o the eff ective diamet er of the fac es.The proximit y assumption is viola ted whene ver fac es ar e close t ogether in c ompar ison t o their eff ective diamet er or ar e adjac ent to one another . In such c ases , the distanc es b etween the c entroid of one fac e and all p oints on the other fac e vary gr eatly. Since the view fac tor dep endenc e on distanc e is nonlinear , the r esult is a p oor estima te of the view fac tor. In the Paramet ers group b ox, you c an set a limit f or the Normaliz ed S epar ation D istanc e, which is the r atio of the minimum fac e separ ation t o the eff ective diamet er of the fac e. If the c omput ed normaliz ed separ ation distanc e is less than the sp ecified v alue , the fac e will then b e divided in to a numb er of subfac es un til the nor maliz ed distanc es of the subfac es ar e gr eater than the sp ecified value . Alternatively, you c an sp ecify the numb er of subfac es to cr eate for such fac es b y en tering a value f or Subdivisions . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1502Modeling H eat Transf erWhile the hemicub e metho d pr ojec ts radia ting sur faces on to a hemicub e, the r ay tracing metho d instead tr aces rays thr ough the c enters of e very hemicub e fac e to det ermine which sur faces ar e visible thr ough tha t fac e. Note tha t the r ay tracing metho d do es not sub divide the fac es (as c an b e done when using the hemicub e metho d by setting the Subdivisions or Normaliz ed S epar ation Distanc e par amet ers), and so the view fac tors ma y be less accur ate than those c alcula ted using the hemicub e metho d for sur faces tha t ha ve a nor maliz ed separ ation distanc e less than 5. To use the r ay tracing metho d to comput e the view fac tors, selec t Ray Tracing from the Metho d list in the View F actors and C lust ering dialo g box.You c an adjust the v alue of the Resolution in the Paramet ers group b ox in or der t o reduc e the impac t of aliasing eff ects, as descr ibed pr eviously . 13.3.4.1.2.3. Accounting for Blo cking S urfaces View fac tor c alcula tions dep end on the geometr ic or ientations of sur face pairs with r espect to each other .Two situa tions ma y be enc oun tered when e xamining sur face pairs: •If ther e is no obstr uction b etween the sur face pairs under c onsider ation, then the y are referred t o as “nonblo cking” surfaces. •If ther e is another sur face blo cking the view s between the sur faces under c onsider ation, then the y are referred t o as “blocking” surfaces. Blocking will change the view fac tors b etween the sur face pairs and requir e additional checks t o comput e the c orrect value of the view fac tors. For c ases with blo cking sur faces, selec t Blocking from the Surfaces list in the View F actors and Clust ering dialo g box. For c ases with nonblo cking sur faces, you c an cho ose either Blocking or Nonblo cking without aff ecting the accur acy. However, it is b etter to cho ose Nonblo cking for such cases , as it tak es less time t o comput e. 13.3.4.1.2.4. Specifying B oundar y Zone P articipation You c an cho ose t o exclude w alls and inlet and e xit b oundar ies fr om par ticipa ting in the view fac tor calcula tion. If you ar e unsur e whether it is nec essar y to calcula te view fac tors f or a par ticular boundar y zone ahead of time , it is r ecommended tha t you allo w it t o par ticipa te; you c an alw ays reverse this decision as par t of a futur e calcula tion r un. There ar e two ways in which y ou c an enable/disable the par ticipa tion of w alls and inlet and e xit boundar ies in the view fac tor c alcula tion. One of those w ays is t o use the Participa tes in View Factor C alcula tion option in the Radia tion tab of the b oundar y condition dialo g box.The other metho d is t o use the Participa ting B oundar y Zones dialo g box (Figur e 13.17: The P articipa ting Boundar y Zones D ialog Box (p.1504 )), which is acc essed b y click ing the Selec t... butt on ne xt to the Zones P articipa ting in View F actor C alcula tion lab el in the View F actors and C lust ering dialo g box. For c ases tha t are made up of a v ery lar ge numb er of z ones , such as under hood applic ations , the la tter metho d is r ecommended . Imp ortant If you c omput e the view fac tors and then la ter alt er which b oundar y zones par ticipa te in the view fac tor c alcula tion, you must r ecomput e the view fac tors so tha t the da ta is up to da te. 1503Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling R adia tionFigur e 13.17: The P articipa ting B oundar y Zones D ialo g Box The Participa ting B oundar y Zones dialo g box allo ws you t o easily sp ecify those z ones tha t are participa ting or non-par ticipa ting without ha ving t o visit the b oundar y conditions dialo g box of each z one . For c ases tha t ha ve a small numb er of b oundar y zones , you c an simply selec t the z ones that you do not w ant to par ticipa te in the view fac tor c alcula tion fr om the Participa ting B oundar y Zones list and click the ar row butt on tha t points to the r ight, so tha t the z ones ar e mo ved t o the Non-P articipa ting B oundar y Zones list; if y ou mak e an er ror, you c an alw ays reverse this pr ocess (tha t is, selec t a z one in the Non-P articipa ting B oundar y Zones list and click the ar row butt on tha t points to the lef t).This c an b e cumb ersome f or c ases tha t ha ve a lar ge numb er of b oundar y zones , and so the f ollowing pr ocedur e is r ecommended inst ead: 1.Make sur e tha t your clust ering options (see Forming Sur face Clusters (p.1498 )) are appr opriate for y our view fac tor settings: a.Selec t Automa tic from the Options list in the Clust ering group b ox of the View Factors and Clust ering dialo g box, as this enables some GUI it ems in the Participa ting B oundar y Zones dialo g box. Imp ortant Note tha t if y ou do not w ant to use the Automa tic option f or the clust ering, you can r evert to the Manual option af ter y ou ar e done using the Participa ting Boundar y Zones dialo g box. b.Verify tha t the w alls y ou sp ecified as cr itical (b y enabling the Critical Z one option in the Radia tion tab of the b oundar y condition dialo g box) also c orrespond t o those tha t are critical for the view factor calcula tion. You must ha ve sp ecified a t least one cr itical zone f or the st eps tha t follow. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1504Modeling H eat Transf er2.Click the Comput e butt on in the Maximum D istanc e from C ritical Z one dialo g box, to up date the value displa yed f or To All O ther Z ones .This v alue r epresen ts the maximum distanc e between the centroids of a cr itical zone and a non-cr itical zone in the mesh; it is f or inf ormation pur poses only , and cannot b e edit ed in this dialo g box. 3.Based on the v alue displa yed f or To All O ther Z ones , enter a thr eshold v alue f or To Participa ting Zones .The v alue y ou en ter will sp ecify the maximum distanc e allo wed b etween the c entroids of a critical zone and a z one tha t par ticipa tes in the view fac tor calcula tion. Then click the Apply butt on t o move all z ones b eyond this distanc e into the Non-P articipa ting B oundar y Zones list. 4.Review the z ones displa yed in the Participa ting B oundar y Zones and Non-P articipa ting B oundar y Zones lists . If nec essar y, selec t zones in these lists and use the ar row butt ons t o mo ve them t o the ap- propriate list , as descr ibed pr eviously . If at an y point you w ant to visually iden tify z ones displa yed in the Participa ting B oundar y Zones and Non-P articipa ting B oundar y Zones lists , selec t the z ones and click the Displa y Zones butt on. Only the selec ted z ones will b e displa yed in the gr aphics windo w. If an y zones ar e displa yed in the Non-P articipa ting B oundar y Zones list, ensur e to en ter an appr o- priate temp erature for Non-P articipa ting B oundar y Zones Temp erature. In most c ases the appr o- priate value is the ambien t temp erature, which b y default is assumed t o be 300 K. After y ou ha ve sp ecified which z ones do not par ticipa te in view fac tor c alcula tion and set their temp erature, click OK to store the settings and close the Participa ting B oundar y Zones dialo g box. You c an then pr oceed t o computing the view fac tors, as descr ibed in the sec tion tha t follows. 13.3.4.2. Computing View F actors ANSY S Fluen t can c omput e the view fac tors f or y our pr oblem in the cur rent session and sa ve them to a file f or use in the cur rent session and futur e sessions . Alternatively, you c an sa ve the sur face clust er inf ormation and view fac tor par amet ers t o a file , calcula te the view fac tors outside ANSY S Fluen t, and then r ead the view fac tors in to ANSY S Fluen t.These metho ds for c omputing view fac tors are descr ibed in the f ollowing sec tions . Imp ortant For lar ge meshes or c omple x mo dels , it is r ecommended tha t you c alcula te the view fac tors outside ANSY S Fluen t and then r ead them in to ANSY S Fluen t before star ting y our simula tion. Note You c an acc elerate view fac tor c alcula tions b y using ANSY S Fluen t in par allel. For mor e information see Accelerating View F actor C alcula tions f or G ener al Purpose C omputing on Graphics P rocessing U nits (GPGPU s) (p.3101 ). 13.3.4.2.1. Computing View F actors Inside ANSY S Fluent To comput e view fac tors in y our cur rent ANSY S Fluen t session, you must first set the par amet ers f or the view fac tor c alcula tion in the View F actors and C lust ering dialo g box (see View F actors and Clustering S ettings (p.1497 ) for details) and click OK to sa ve them. When y ou ha ve set the view fac tor and sur face clust er par amet ers, click the Comput e/W rite/Read ... butt on in the View F actors and Clust ering group b ox of the Radia tion M odel dialo g box. A Selec t File dialo g box will op en, 1505Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling R adia tionprompting y ou f or the name of the file in which ANSY S Fluen t should sa ve the sur face clust er inf orm- ation and the view fac tors. Note tha t the option t o Write Binar y Files is enabled b y default , in or der to reduc e the time needed t o wr ite and r ead the view fac tor files .When y ou click OK in the Selec t File dialo g box, ANSY S Fluen t will wr ite the sur face clust er inf ormation t o the file . ANSY S Fluen t will use the sur face clust er inf ormation t o comput e the view fac tors, save the view fac tors t o the same file, and then aut oma tically r ead the view fac tors.The ANSY S Fluen t console will r eport the sta tus of the view fac tor c alcula tion. For e xample: Completed 25% calculation of view factors Completed 50% calculation of view factors Completed 75% calculation of view factors Completed 100 % calculation of view factors Imp ortant •You must r ecomput e the view fac tors if y ou tak e an y of f ollowing ac tions af ter the initial computa tion: –if you alt er which b oundar y zones par ticipa te in the view fac tor calcula tion (either b y using the Participa ting B oundar y Zones dialo g box, or b y enabling / disabling the Participa tes in View Factor C alcula tion option in the Radia tion tab of the b oundar y condition dialo g box) –if you sc ale or unsc ale the mesh b y using the Scale M esh dialo g box •The view fac tor file f ormat for this v ersion of ANSY S Fluen t is k nown as the c ompr essed r ow format (CRF) and is a mor e efficien t way of wr iting view fac tors than in v ersions tha t are pr ior to Fluen t 6.4. In the CRF f ormat, only nonz ero view fac tors with their asso ciated clust er IDs are stored t o the file .This r educ es the siz e of the .s2s file, and r educ es the time it tak es to read the file in to ANSY S Fluen t.While the CRF file f ormat is the default , you c an still use the older file f ormat if nec essar y. Contact your supp ort engineer f or mor e inf ormation. •View fac tors using r ay tracing ar e comput ed with the MPI/Op enMP h ybrid mo del f or par allel runs. By default , one Op enMP thr ead is used p er MPI pr ocess, as sp ecified in the Thread Control D ialog Box (p.3934 ) (see Controlling the Threads (p.3095 ) for details). To use all the available c ores on y our machine as Op enMP thr eads , selec t Numb er of C ores on M achine . A Fixed N umb er of c ores c an also b e used based on y our needs . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1506Modeling H eat Transf erFigur e 13.18: The Thread C ontrol D ialo g Box Note For c ases tha t use the S2S mo del and c ontain non-c onformal in terfaces, if the mesh interfaces ar e defined af ter the c ase has b een r ead, then the in tersec tion of the in ter- face zones will o ccur dur ing the initializa tion pr ocess, which will c ause r elab eling of faces thr oughout the domain. If you a ttempt t o comput e view fac tors b efore solution initializa tion in such a c ase, then the f ollowing message will b e displa yed in the console and the view fac tors will b e comput ed aut oma tically dur ing solution initial- ization t o avoid a misma tch with the c ase file: Intersection zones for non-conformal interfaces are not created. View factors will be computed during solution initialization. 13.3.4.2.2. Computing View F actors O utside ANSY S Fluent To comput e view fac tors outside ANSY S Fluen t, you must sa ve the sur face clust er inf ormation and view fac tor par amet ers t o a file . File → Write → Surface Clust ers... ANSY S Fluen t will op en the View F actors and C lust ering dialo g box, wher e you will set the view factor and sur face clust er par amet ers (see View F actors and C lustering S ettings (p.1497 ) for details). When y ou click OK in the View F actors and C lust ering dialo g box, a Selec t File dialo g box will open, prompting y ou f or the name of the file in which ANSY S Fluen t should sa ve the sur face clust er information and view fac tor par amet ers t o the file . If the sp ecified Filename ends in .gz or .Z, appr opriate file c ompr ession will b e performed . To calcula te the view fac tors outside ANSY S Fluen t, enter one of the f ollowing c ommands: •For the ser ial solv er: utility viewfac inputfile wher e inputfile is the filename , or the c orrect pa th to the filename , for the sur face clust er inf orm- ation and view fac tor par amet ers file tha t you sa ved fr om ANSY S Fluen t.You c an then r ead the view fac tors in to ANSY S Fluen t, as descr ibed b elow. 1507Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling R adia tion•For the par allel solv er: –Viewfac utilit y mo dule: utility viewfac -t npr ocs [-p interconnec t] [-mpi= mpi_t ype] [-cnf= hosts]in- putfile wher e inputfile is the filename , for which y ou will need t o pr ovide the full pa th. –Raytracing utilit y mo dule: utility raytracing -t npr ocs [-p interconnec t] [-mpi= mpi_t ype] [-cnf= hosts ][-ompthreads= N]inputfile wher e inputfile is the filename , for which y ou will need t o pr ovide the full pa th. On Windo ws: -tnpr ocs specifies the numb er of pr ocesses t o use .When the -cnf option is pr esen t, the hosts file ar gumen t is used t o det ermine which machines t o use f or the par allel job . For e x- ample , if ther e ar e 8 machines list ed in the hosts file and y ou w ant to run a job with 4 pr ocesses , set npr ocs to 4 (tha t is -t4 ) and ANSY S Fluen t will use the first 4 machines list ed in the hosts file. Note tha t this do es not apply t o the C omput e Cluster S erver (C CS). -pinterconnec t (optional) sp ecifies the t ype of in terconnec t.The ether net in terconnec t is used by default if the option is not e xplicitly sp ecified . See Table 43.2: Supp orted In terconnec ts for the Windo ws Platform (p.3060 ),Table 43.3: Available MPI s for Windo ws Platforms (p.3060 ), and Table 43.4: Supp orted MPI s for Windo ws Architectures (P er In terconnec t) (p.3061 ) for mor e in- formation. -mpi= mpi_t ype (optional) sp ecifies the t ype of MPI. If the option is not sp ecified , the default MPI f or the giv en in terconnec t (IBM MPI) will b e used (the use of the default MPI is r ecommen- ded). The a vailable MPI s for Windo ws are sho wn in Table 43.3: Available MPI s for Windo ws Platforms (p.3060 ). -cnf= hosts (optional) sp ecifies the hosts file , which c ontains a list of the machines on which you w ant to run the par allel job .This option func tions the same as tha t in the c ommand f or launching par allel F luen t; see Starting P arallel ANSY S Fluen t on a Windo ws System U sing Command Line Options (p.3058 ) for details . -ompthreads= N (optional) sp ecifies tha t the desir ed numb er of Op enMP thr eads t o be used per machine is N. On Linux : -tnpr ocs specifies the numb er of pr ocesses t o used .When the -cnf option is pr esen t, the hosts file ar gumen t is used t o det ermine which machines t o use f or the par allel job . For e x- ample , if ther e ar e 10 machines list ed in the hosts file and y ou w ant to run a job with 5 pr o- cesses , set npr ocs to 5 (tha t is -t5 ) and ANSY S Fluen t will use the first 5 machines list ed in the hosts file . -pinterconnec t (optional) sp ecifies the t ype of in terconnec t.The ether net in terconnec t is used by default if the option is not e xplicitly sp ecified . See Table 43.5: Supp orted In terconnec ts for Linux P latforms (P er P latform) (p.3065 ),Table 43.6: Available MPI s for Linux P latforms (p.3066 ), and Table 43.7: Supp orted MPI s for Linux A rchitectures (P er In terconnec t) (p.3066 ) for mor e in- formation. -mpi= mpi_t ype (optional) sp ecifies the t ype of MPI. If the option is not sp ecified , the default MPI f or the giv en in terconnec t will b e used (the use of the default MPI is r ecommended). The available MPI s for Linux ar e sho wn in Table 43.6: Available MPI s for Linux P latforms (p.3066 ). -cnf= hosts (optional) sp ecifies the hosts file , which c ontains a list of the machines on which you w ant to run the par allel job .This option func tions the same as tha t in the c ommand f or Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1508Modeling H eat Transf erlaunching par allel F luen t; see Starting P arallel ANSY S Fluen t on a Linux S ystem U sing C ommand Line Options (p.3064 ) for details . -ompthreads= N (optional) sp ecifies tha t the desir ed numb er of Op enMP thr eads t o be used per machine is N. 13.3.4.3. Reading View F actors int o ANSY S Fluent If the view fac tors f or y our pr oblem ha ve alr eady been c omput ed (either inside or outside ANSY S Fluen t) and sa ved t o a file , you c an r ead them in to ANSY S Fluen t.To read in the view fac tors, click Read E xisting F ile... butt on in the View F actors and C lust ering group b ox of the Radia tion M odel dialo g box. A Selec t File dialo g box will op en wher e you c an sp ecify the name of the file c ontaining the view fac tors. Alternatively, you c an r ead the view fac tors file using the File/Read/Vie w F actors... ribbon tab it em. Imp ortant While the pr evious .s2s view fac tor file f ormat can still b e read seamlessly in to ANSY S Fluen t, ther e is no w a mor e efficien t compr essed r ow format (CRF) tha t can b e read in to ANSY S Fluen t (see the sec tion on C omputing View F actors Inside ANSY S Fluen t).You c an take ad vantage of the r educ ed siz e of the CRF file and ther efore the r educ ed time it tak es to read the file in to ANSY S Fluen t, by converting the e xisting old file f ormat to the new format (without ha ving t o recomput e the view fac tors) using the f ollowing c ommand a t the c ommand pr ompt in y our w orking dir ectory: utility viewfac -c1 -o new.s2s.gz old.s2s.gz wher e new.s2s.gz is the CRF f ormat to which y ou w ant the old file f ormat (old.s2s.gz ) converted. 13.3.5. Setting U p the DO M odel For inf ormation ab out setting up the DO mo del, see the f ollowing sec tions: 13.3.5.1. Angular D iscretiza tion 13.3.5.2. Defining N on-G ray Radia tion f or the DO M odel 13.3.5.3. Enabling DO/Ener gy Coupling For inf ormation ab out acc elerating the DO solv er, see Accelerating D iscrete Or dina tes (DO) R adia tion Calcula tions (p.3102 ). 13.3.5.1. Angular D iscr etization When y ou selec t the Discr ete Or dina tes mo del, the Radia tion M odel dialo g box will e xpand t o show inputs f or Angular D iscr etiza tion (see Figur e 13.11: The R adia tion M odel D ialog Box (DO Model) (p.1490 )). In this sec tion, you will set par amet ers f or the angular discr etiza tion and pix elation descr ibed in Angular D iscretiza tion and P ixelation in the Theor y Guide . Theta D ivisions ( ) and Phi D ivisions ( ) will define the numb er of c ontrol angles used t o discr etize each o ctant of the angular spac e (see Figur e 5.3: Angular C oordina te System in the Theor y Guide ). Note tha t higher le vels of discr etiza tion ar e recommended f or pr oblems wher e sp ecular e xchange of radia tion is imp ortant to incr ease the lik eliho od of the c orrect beam dir ection b eing c aptur ed. For a 2D mo del, ANSY S Fluen t will solv e only 4 o ctants (due t o symmetr y); ther efore, a total of dir- 1509Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling R adia tionections will b e solv ed. For a 3D mo del, 8 o ctants ar e solv ed, resulting in directions . By default , the numb er of Theta D ivisions and the numb er of Phi D ivisions are both set t o 2. For most practical pr oblems , these settings ar e acc eptable , however, a setting of 2 is c onsider ed t o be a c oarse estima te. Incr easing the discr etiza tion of Theta D ivisions and Phi D ivisions to a minimum of 3, or up t o 5, will achie ve mor e reliable r esults . A finer angular discr etiza tion c an b e sp ecified t o better resolv e the influenc e of small geometr ic features or str ong spa tial v ariations in t emp erature, but lar ger numb ers of Theta D ivisions and Phi D ivisions will add t o the c ost of the c omputa tion. Theta P ixels and Phi P ixels are used t o control the pix elation tha t acc oun ts for an y control volume overhang (see Figur e 5.7: Pixelation of C ontrol A ngle in the Theor y Guide and the figur es and discussion preceding it). For pr oblems in volving gr ay-diffuse r adia tion, the default pix elation of is usually sufficien t. For pr oblems in volving symmetr y, periodic, specular , or semi-tr anspar ent boundar ies, a pixelation of is recommended and will achie ve acc eptable r esults .The c omputa tional eff ort, as a result of incr easing the pix elation, is less than the c omputa tional eff ort caused b y incr easing the divisions .You should b e aware, however, tha t incr easing the pix elation adds t o the c ost of c omputa tion. Imp ortant Note tha t pix elations ar e applied t o boundar y fac es b y default. 13.3.5.2. Defining N on-Gr ay Radiation for the DO Mo del If you w ant to mo del non-gr ay radia tion using the DO mo del, you c an sp ecify the Numb er of B ands ( ) under Non-G ray M odel in the e xpanded Radia tion M odel dialo g box (Figur e 13.19: The R adia tion Model D ialog Box (N on-G ray DO M odel) (p.1511 )). For a 2D mo del, ANSY S Fluen t will solv e directions . For a 3D mo del, directions will b e solv ed. By default , the Numb er of B ands is set t o zero, indic ating tha t only gr ay radia tion will b e mo deled . Because the c ost of c omputa tion in- creases dir ectly with the numb er of bands , you should tr y to minimiz e the numb er of bands used . In man y cases , the absor ption c oefficien t or the w all emissivit y is eff ectively c onstan t for the w avelengths of imp ortanc e in the t emp erature range of the pr oblem. For such c ases , the gr ay DO mo del c an b e used with little loss of accur acy. For other c ases , non-gr ay behavior is imp ortant, but r elatively f ew bands ar e nec essar y. For typic al glasses , for e xample , two or thr ee bands will fr equen tly suffic e. When a nonz ero Numb er of B ands is sp ecified , the Radia tion M odel dialo g box will e xpand onc e again t o sho w the Wavelength In tervals (Figur e 13.19: The R adia tion M odel D ialog Box (N on-G ray DO M odel) (p.1511 )).You c an sp ecify a Name for each w avelength band , as w ell as the Start and End wavelength of the band in m. Note tha t the w avelength bands ar e sp ecified f or v acuum ( ). ANSY S Fluen t will aut oma tically acc oun t for the r efractive inde x in setting band limits f or media with diff erent from unit y. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1510Modeling H eat Transf erFigur e 13.19: The R adia tion M odel D ialo g Box (N on-G ray DO M odel) The fr equenc y of r adia tion r emains c onstan t as r adia tion tr avels acr oss a semi-tr anspar ent interface. The w avelength, however, changes such tha t is c onstan t.Therefore, when r adia tion passes fr om a medium with r efractive inde x to one with r efractive inde x , the f ollowing r elationship holds: (13.8) Here and are the w avelengths asso ciated with the t wo media. It is c onventional t o sp ecify the wavelength r ather than fr equenc y. ANSY S Fluen t requir es y ou t o sp ecify w avelength bands (in m) for an equiv alen t medium with . For e xample , consider a t ypic al glass with a st ep jump in the absor ption c oefficien t at a cut-off wavelength of .The absor ption c oefficien t is for and for .The r efractive inde x of the glass is . Since is c onstan t acr oss a semi-tr anspar ent interface, the equiv alen t cut-off wavelength f or a medium with is using Equa tion 13.8 (p.1511 ).You should cho ose t wo bands in this c ase, with the limits 0 t o and to 100. Here, the upp er w avelength limit has b een chosen t o be a lar ge numb er, 100, in or der t o ensur e tha t the en tire sp ectrum is c overed b y the bands .When multiple ma terials e xist, you should c onvert all the cut-off w avelengths t o equiv alen t cut-off w avelengths f or an medium, and cho ose the band b oundar ies acc ordingly . The bands c an ha ve diff erent widths and need not b e contiguous .You c an ensur e tha t the en tire spectrum is c overed b y your bands b y cho osing and . Here and are the minimum and maximum w avelength b ounds of y our w avelength bands , and is the minimum e xpected t emp erature in the domain. ANSY S Fluen t allo ws you t o use a user-defined func tion (UDF) t o mo dify the emissivit y weigh ting factor (which other wise defaults t o the black b ody emission fac tor obtained from a standar d Planck distr ibution). The emissivit y weigh ting fac tor app ears in the emission t erm of 1511Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling R adia tionthe r adia tive transf er equa tion f or the non-gr ay mo del, as sho wn in Equa tion 5.61 in the Theor y Guide . For mor e inf ormation, see DEFINE_EMISSIVITY_WEIGHTING_FACTOR in the Fluen t Customiza tion Manual . 13.3.5.3. Enabling DO/E ner gy Coupling For applic ations in volving optic al thick nesses gr eater than 10, you c an enable the DO/E nergy Coupling option in the Radia tion M odel (Figur e 13.20: The R adia tion M odel D ialog Box with DO/Ener gy Coupling Enabled (p.1512 )) in or der t o couple the ener gy and in tensit y equa tions a t each cell, solving them simultaneously .This appr oach acc elerates the c onvergenc e of the finit e volume scheme f or radia tive hea t transf er and c an b e used with the gr ay or non-gr ay radia tion mo del. Figur e 13.20: The R adia tion M odel D ialo g Box with DO/E nergy Coupling E nabled 13.3.6. Setting U p the MC M odel In the Iteration P aramet ers group b ox of the Radia tion M odel dialo g box, you ha ve the option of revising the Target N umb er of Hist ories to be tracked f or the M onte Carlo (MC) simula tion. The default value is 100,000. This c an ha ve a lar ge eff ect on the accur acy of simula tion r esults . For details , see Monte Carlo S olution A ccur acy in the Theor y Guide . In some c ases , Fluen t migh t calcula te substan tially mor e hist ories than the sp ecified Target N umb er of Hist ories, par ticular ly if a fine sur face mesh is used .The solv er will ensur e tha t an appr opriate minimum numb er of hist ories ar e star ted a t each sur face fac e, and tha t can incr ease the t otal numb er of hist ories tha t are used dur ing the c alcula tion. Thus the CPU usage ma y not sc ale dir ectly with changes t o the sp ecified tar get. In the Mesh Options group b ox, you c an c oarsen the r adia tion mesh b y sp ecifying a Target C ells P er Volume C lust er greater than one . By default , it is set t o one which implies no c oarsening . Any value Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1512Modeling H eat Transf ergreater than one r educ es the numb er of eff ective cells in the domain used b y the MC r adia tion mo del. The c oarsening is achie ved b y mer ging c ells t ogether and , ther efore, does not aff ect the sur face mesh resolution or alt er the fac es of an y mer ged c ells.The r educ tion in c ells ma y sp eed up the r adia tion calcula tion and r educ e peak memor y usage , however, it ma y also ha ve an impac t on solution accur acy. You ha ve the option sp ecifying multiple r adia tion bands using the Non-G ray M odel group b ox. For each desir ed band , you must sp ecify a star t and end w avelength similar t o Defining N on-G ray Radia tion for the DO M odel (p.1510 ). Figur e 13.21: The R adia tion M odel D ialo g Box (MC) 13.3.7. Defining M aterial P roperties f or R adia tion When y ou ar e using the P-1, DO , MC, or R osseland r adia tion mo del in ANSY S Fluen t, you should b e sure to define b oth the absor ption and sc attering c oefficien ts of the fluid in the Create/Edit M aterials dialo g box. Note tha t you c an either en ter a c onstan t value f or these par amet ers, or y ou c an sp ecify them using a user-defined func tion (UDF). For mor e inf ormation, see DEFINE_PROPERTY UDFs in the Fluen t Customiza tion M anual . 1513Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling R adia tionSetup → Materials If you ar e mo deling semi-tr anspar ent media using the DO or MC mo del, you should also define the refractive inde x for the semi-tr anspar ent fluid or solid ma terial.When using the R osseland mo del, you can sp ecify the r efractive inde x only f or the fluid ma terial.When using the P-1 mo del, you should define the r efractive inde x for the fluid ma terial only . For the DTRM, you need t o define only the ab- sorption c oefficien t. If your mo del includes gas phase sp ecies such as c ombustion pr oduc ts, absor ption and/or sc attering in the gas ma y be signific ant.The sc attering c oefficien t should b e incr eased fr om the default of z ero if the fluid c ontains disp ersed par ticles or dr oplets tha t contribut e to sc attering. Alternatively, you c an specify the sc attering c oefficien t as a user-defined func tion (UDF). For mor e inf ormation, see DEFINE_PROPERTY UDFs in the Fluen t Customiza tion M anual . ANSY S Fluen t allo ws you t o en ter a c omp osition-dep enden t absor ption c oefficien t for and mixtures, using the WSGGM. The metho d for c omputing a v ariable absor ption c oefficien t is descr ibed in Radia tion in C ombusting F lows in the Theor y Guide .Radia tion P roperties (p.1137 ) provides a detailed descr iption of the pr ocedur es used f or sp ecific ation of r adia tion pr operties. 13.3.7.1. Absorption C oefficient for a N on-Gr ay Mo del If you ar e using the non-gr ay P-1, DO , or MC mo del, you c an sp ecify a diff erent constan t absor ption coefficien t for each of the bands used b y the gr ay-band mo del, as descr ibed in Radia tion P roper- ties (p.1137 ).You c annot , however, comput e a c omp osition-dep enden t absor ption c oefficien t in each band . If you use the WSGGM t o comput e a v ariable absor ption c oefficien t, the v alue will b e the same for all bands . Alternatively, you c an sp ecify a user-defined func tion (UDF) f or the absor ption c oefficien t. For mor e inf ormation, see DEFINE_PROPERTY UDFs in the Fluen t Customiza tion M anual . 13.3.7.2. Refractive Inde x for a N on-Gr ay Mo del If you ar e using the non-gr ay P-1, DO , or MC mo del, you c an sp ecify a diff erent constan t refractive inde x for each of the bands used b y the gr ay-band mo del, as descr ibed in Radia tion P roperties (p.1137 ). You c annot , however, comput e a c omp osition-dep enden t refractive inde x in each band . 13.3.8. Defining B oundar y Conditions f or R adia tion When y ou set up a pr oblem tha t includes r adia tion, you will set additional b oundar y conditions a t inlets , exits, and w alls.These inputs ar e descr ibed in the sec tions tha t follow.The b oundar y condition dialo g boxes c an b e op ened b y right-click ing the b oundar y name in the tr ee (under Setup/B oundar y Condi- tions ) and click ing Edit... in the menu tha t op ens; alternatively, you c an op en them fr om the Boundar y Conditions task page: Setup → Boundar y Conditions 13.3.8.1. Inlet and E xit B oundar y Conditions 13.3.8.1.1. Emissivit y When r adia tion is ac tive, you c an define the emissivit y at each inlet and e xit b oundar y when y ou are defining b oundar y conditions in the asso ciated inlet or e xit b oundar y dialo g box (for e xample , Pressur e Inlet dialo g box,Velocity Inlet dialo g box,Pressur e Outlet dialo g box). Enter the appr o- Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1514Modeling H eat Transf erpriate value f or Internal E missivit y.The default v alue f or all b oundar y types is 1. Alternatively, you can sp ecify a user-defined func tion f or emissivit y. For mor e inf ormation, see DEFINE_PROFILE in the Fluen t Customiza tion M anual . For the non-gr ay P-1 mo del and the non-gr ay DO mo del, the sp ecified c onstan t emissivit y will b e used f or all w avelength bands . Imp ortant The Internal E missivit y boundar y condition is not a vailable with the R osseland mo del. 13.3.8.1.2. Black B ody Temp eratur e ANSY S Fluen t includes an option tha t allo ws you t o tak e in to acc oun t the influenc e of the t emp erature of the gas and the w alls b eyond the inlet/e xit b oundar ies, and sp ecify diff erent temp eratures for radia tion and c onvection a t inlets and e xits.This is useful when the t emp erature outside the inlet or e xit diff ers c onsider ably fr om the t emp erature in the enclosur e. For e xample , if the t emp erature of the w alls b eyond the inlet is 2000 K and the t emp erature at the inlet is 1000 K, you c an sp ecify the outside w all t emp erature to be used f or c omputing r adia tive hea t flux, while the ac tual t emp er- ature at the inlet is used f or c alcula ting c onvective hea t transf er.To do this , you w ould sp ecify a radia tion t emp erature of 2000 K as the black b ody temp erature. Although this option allo ws you t o acc oun t for b oth c ooler and hott er outside w alls, you must use caution in the c ase of c ooler w alls, sinc e the r adia tion fr om the immedia te vicinit y of the hott er inlet or outlet almost alw ays domina tes o ver the r adia tion fr om c ooler outside w alls. If, for e xample , the temp erature of the outside w alls is 250 K and the inlet t emp erature is 1500 K, it migh t be misleading to use 250 K f or the r adia tion b oundar y temp erature.This t emp erature migh t be expected t o be somewher e between 250 K and 1500 K; in most c ases it will b e close t o 1500 K. Its value dep ends on the geometr y of the outside w alls and the optic al thick ness of the gas in the vicinit y of the inlet. In the flo w inlet or e xit dialo g box (for e xample ,Pressur e Inlet dialo g box,Velocity Inlet dialo g box), selec t Specified E xternal Temp erature in the External Black B ody Temp erature M etho d drop-do wn list , and then en ter the v alue of the r adia tion b oundar y temp erature as the Black B ody Temp erature. Imp ortant •If you w ant to use the same t emp erature for radia tion and c onvection, retain the default se- lection of Boundar y Temp erature as the External Black B ody Temp erature M etho d. •The Black B ody Temp erature boundar y condition is not a vailable with the R osseland mo del. 13.3.8.2. Wall B oundar y Conditions for the DTRM, and the P -1, S2S, and R osseland Mo dels The DTRM and the S2S, Rosseland , and gr ay P-1 (tha t is,Numb er of B ands is set t o zero) mo dels as- sume all w alls t o be gr ay and diffuse .The only r adia tion b oundar y condition r equir ed in the Wall dialo g box is the emissivit y. For the R osseland mo del, the in ternal emissivit y is 1. For the DTRM and the S2S and gr ay P-1 mo dels , you c an en ter the appr opriate value f or Internal E missivit y in the Thermal tab of the Wall dialo g box.The default v alue is 1. Alternatively, you c an sp ecify a user-defined 1515Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling R adia tionfunc tion f or emissivit y. For mor e inf ormation, see DEFINE_PROFILE in the Fluen t Customiza tion Manual . For the non-gr ay P–1 mo del, specify a c onstan t Internal E missivit y for each w avelength band in the Radia tion tab of the Wall dialo g box (the default v alue in each band is 1). Alternatively, you c an specify the in ternal emissivit y using a b oundar y condition par amet er (see Creating a N ew P aramet- er (p.845)). See Defining B oundar y Conditions f or R adia tion (p.1514 ) for details . 13.3.8.2.1. Boundar y Conditions for the S2S Mo del When the S2S mo del is used , you c an sp ecify tha t some of the w alls and inlet and e xit b oundar ies are not par ticipa ting in the view fac tor c alcula tion. This c apabilit y allo ws you t o sa ve time c omputing the view fac tors and also r educ e the memor y requir ed t o store the view fac tor file dur ing the ANSY S Fluen t calcula tion. See Specifying B oundar y Zone P articipa tion (p.1503 ) for details . Imp ortant •Whene ver you r evise which b oundar y zones par ticipa te in the c alcula tion, you will need t o recomput e the view fac tors. •The Flux Rep orts dialo g box will not sho w the e xact balanc e of the Radia tion H eat Transf er Rate because the r adia tive hea t transf er to those b oundar ies tha t do not par ticipa te in the view fac tor calcula tion is not included . 13.3.8.3. Wall B oundar y Conditions for the DO Mo del When the DO mo del is used , you c an mo del opaque w alls, as discussed in Boundar y and C ell Z one Condition Treatmen t at Opaque Walls in the Theor y Guide , as w ell as semi-tr anspar ent walls ( Cell Zone and B oundar y Condition Treatmen t at Semi-T ranspar ent Walls in the Theor y Guide ). You c an use a diffuse w all t o mo del w all b oundar ies in man y industr ial applic ations sinc e, for the most par t, sur face roughness mak es the r eflec tion of inciden t radia tion diffuse . For highly p olished surfaces, such as r eflec tors or mir rors, the sp ecular b oundar y condition is appr opriate.The semi- transpar ent boundar y condition c an b e appr opriate, for e xample , when mo deling f or glass panes in air. 13.3.8.3.1. Opaque Walls In the Radia tion tab of the Wall dialo g box (Figur e 13.22: The Wall D ialog Box Showing R adia tion Conditions f or an Opaque Wall (p.1517 )), selec t opaque in the BC Type drop-do wn list t o sp ecify an opaque w all. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1516Modeling H eat Transf erFigur e 13.22: The Wall D ialo g Box Showing R adia tion C onditions f or an Opaque Wall Specify the fr action of r eflec ted r adia tion flux tha t is t o be treated as diffuse . By default , the Diffuse Fraction is set t o , indic ating tha t all of the r adia tion is diffuse . A diffuse fr action equal t o indic ates purely sp ecular r eflec ted r adia tion. A diffuse fr action b etween and will r esult in par tially diffuse and par tially sp ecular r eflec ted ener gy. If the non-gr ay DO mo del is b eing used , the Diffuse F raction can b e sp ecified f or each band . See Boundar y and C ell Z one C ondition Treatmen t at Opaque Walls in the Theor y Guide f or mor e details . You will also b e requir ed t o sp ecify the in ternal emissivit y in the Thermal tab of the Wall dialo g box (Figur e 13.23: The Wall D ialog Box Showing In ternal Emissivit y Thermal C onditions f or an Opaque Wall (p.1518 )). For gr ay-radia tion DO mo dels , enter the appr opriate value f or Internal E missivit y (default v alue is 1). For non-gr ay DO mo dels , specify a c onstan t Internal E missivit y for each wavelength band in the Radia tion tab of the Wall dialo g box. (The default v alue in each band is 1.) Alternatively, you c an sp ecify the in ternal emissivit y using a b oundar y condition par amet er (see Creating a N ew P aramet er (p.845)). 1517Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling R adia tionFigur e 13.23: The Wall D ialo g Box Showing In ternal E missivit y Thermal C onditions f or an Opaque Wall You c an also sp ecify the e xternal emissivit y and e xternal r adia tion t emp erature for an opaque w all when the ther mal c onditions ar e set t o Radia tion or Mixed in the Wall dialo g box (Figur e 13.24: The Wall D ialog Box Showing Ex ternal Emissivit y and Ex ternal R adia tion Temp erature Thermal C ondi- tions (p.1519 )). Alternatively, you c an sp ecify a UDF f or these par amet ers; for mor e inf ormation, see DEFINE_PROFILE in the Fluen t Customiza tion M anual . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1518Modeling H eat Transf erFigur e 13.24: The Wall D ialo g Box Showing E xternal E missivit y and E xternal R adia tion Temp erature Thermal C onditions For mor e inf ormation on b oundar y condition tr eatmen t at opaque w alls, see Boundar y and C ell Z one Condition Treatmen t at Opaque Walls in the Theor y Guide . 13.3.8.3.2. Semi-T ranspar ent Walls To define r adia tion f or an e xterior semi-tr anspar ent wall, click the Radia tion tab in the Wall dialo g box and then selec t semi-tr anspar ent in the BC Type drop-do wn list ( Figur e 13.25: The Wall D ialog Box for a S emi-T ranspar ent Wall B oundar y (p.1520 )).The dialo g box will e xpand t o displa y the semi- transpar ent wall inputs needed t o define an e xternal ir radia tion flux ( Figur e 13.25: The Wall D ialog Box for a S emi-T ranspar ent Wall B oundar y (p.1520 )). 1519Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling R adia tionFigur e 13.25: The Wall D ialo g Box for a S emi-T ranspar ent Wall B oundar y Then p erform the f ollowing st eps: 1.Specify the v alue of the ir radia tion flux (in W/m2) under Direct or Diffuse Ir radia tion . If the non-gr ay DO mo del is b eing used , a constan t Direct or Diffuse Ir radia tion can b e sp ecified f or each band . Imp ortant Note tha t the e xternal diffuse ir radia tion sp ecified when using Radia tion or Mixed ther mal c onditions (selec ted in the Thermal tab), or Diffuse Ir radia tion (in the Radi- ation tab) is alw ays distr ibut ed hemispher ically af ter tr ansmission thr ough semi- transpar ent walls (tha t is indep enden t of whether the e xternal semi-tr anspar ent boundar y wall is defined as a diffusely or sp ecular ly reflec ting t ype). 2.Apply D irect Irradia tion P arallel t o the B eam is the default means of sp ecifying the sc ale of ir radia tion flux. When enabled , ANSY S Fluen t assumes tha t the v alue of Direct Irradia tion tha t you sp ecify is the irradia tion flux par allel t o the Beam D irection .When deselec ted, ANSY S Fluen t inst ead assumes tha t the v alue sp ecified is the flux par allel t o the fac e nor mals and will c alcula te the r esulting b eam par allel flux f or e very fac e. See Figur e 5.12: DO Ir radia tion on Ex ternal S emi-T ranspar ent Wall in Semi-T ranspar ent Exterior Walls in the Theor y Guide for details . 3.Define the Beam Width by sp ecifying the b eam Theta and Phi extents. Beam width is sp ecified as the solid angle o ver which the ir radia tion is distr ibut ed.The default v alue f or b eam width is , which is Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1520Modeling H eat Transf ersuitable f or collima ted b eam r adia tion. A b eam width less than this is lik ely t o result in z ero irradia tion flux. 4.Specify the ( X,Y,Z) vector tha t defines the Beam D irection .The b eam dir ection is defined as the v ector of the c entroid of the solid angle (b eam width). You c an sp ecify the Beam D irection as a c onstan t, a profile or a UDF .This is esp ecially useful in applic ations wher e the shap e of the r adia tive sour ce is cir cular or c ylindr ical (or nonlinear). For inf ormation ab out b oundar y pr ofiles , see Reading and Writing P rofile Files (p.594). Note tha t the ac tual dir ection of the b eam of r adia tion tha t en ters the domain will b e fur ther influenc ed b y the solid angles a vailable fr om the numb er of divisions set up; the eff ective dir ection will b e the dir ection v ector of the solid angle tha t the inc oming b eam falls in to. Finally , any nonz ero diffuse fr action will ac t to spr ead out (hemispher ically, proportional t o the diffuse fr action) the ir radia tion tha t en ters the domain. For a UDF e xample tha t sp ecifies the b eam dir ection, see Example 5 - B eam D irection P rofile a t Semi-T ranspar ent Walls in the Fluen t Customiza tion M anual . 5.Specify the Diffuse F raction , the fr action of the r eflec ted r adia tion fr om the w all tha t is tr eated as diffuse between 0 and 1 . By default , the Diffuse F raction is set t o 1, indic ating tha t all of the r adia tion is diffuse . A Diffuse F raction of 0 tr eats the r eflec ted r adia tion as pur ely sp ecular . If you sp ecify a v alue b etween 0 and 1 , the r adia tion is tr eated as par tially diffuse and par tially sp ecular . If the non-gr ay DO mo del is being used , the Diffuse F raction can b e sp ecified f or each band . See Diffuse S emi-T ranspar ent Walls in the Theor y Guide for details . Imp ortant •Note tha t the r efractive inde x of the e xternal medium is assumed t o be 1. •If Heat Flux conditions ar e sp ecified in the Thermal tab of the Wall dialo g box, the sp ecified heat flux is c onsider ed t o be only the c onduc tion and c onvection p ortion of the b oundar y flux. The giv en ir radia tion sp ecifies the inc oming e xterior r adia tive flux; the r adia tive flux transmitt ed fr om the domain in terior t o the outside is c omput ed as a par t of the c alcula tion by ANSY S Fluen t. Internal emissivit y is ignor ed f or semi-tr anspar ent sur faces. •Note tha t when a b oundar y wall is made semi-tr anspar ent ANSY S Fluen t calcula tes the amoun t of radia tion lea ving as w ell as en tering the domain. If you do not pr ovide a sour ce of ir radia tion or a r adia ting ther mal c ondition (f or e xample Mixed or Radia tion ) then y ou ar e eff ectively radia ting t o a t emp erature of K and it is highly lik ely y ou ma y obser ve temp eratures in y our model tha t are lower than e xpected. Ensur e tha t the e xternal (inc oming) r adian t conditions give go od acc oun t of the sur roundings . You c an also sp ecify the e xternal emissivit y and e xternal r adia tion t emp erature for a semi-tr anspar ent wall when the ther mal c onditions ar e set t o Radia tion or Mixed in the Wall dialo g box (Fig- ure 13.24: The Wall D ialog Box Showing Ex ternal Emissivit y and Ex ternal R adia tion Temp erature Thermal C onditions (p.1519 )). Alternatively, you c an sp ecify a user-defined func tion (UDF) f or these paramet ers; for mor e inf ormation, see DEFINE_PROFILE in the Fluen t Customiza tion M anual . For a detailed descr iption of b oundar y condition tr eatmen t at semi-tr anspar ent walls, see Cell Z one and B oundar y Condition Treatmen t at Semi-T ranspar ent Walls in the Theor y Guide . 1521Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling R adia tionTo define r adia tion f or an in terior (t wo-sided) semi-tr anspar ent wall, in the Wall dialo g box click the Radia tion tab and then selec t semi-tr anspar ent in the BC Type drop-do wn list ( Figur e 13.26: The Wall D ialog Box for an In terior S emi-T ranspar ent Wall (p.1522 )).Then sp ecify the Diffuse F raction as descr ibed f or the pr evious c ase. Imp ortant Note tha t for semi-tr anspar ent walls, the in ternal emissivit y defined under ther mal c ondi- tions is ignor ed. If you w ant to include the eff ect of in ternal emissivit y at semi-tr anspar ent walls, you must cr eate a solid z one and sp ecify tha t it par ticipa tes in the r adia tion c alcu- lation; see Solid S emi-T ranspar ent Media in the Theor y Guide for details . Figur e 13.26: The Wall D ialo g Box for an In terior S emi-T ranspar ent Wall 13.3.8.4. Wall B oundar y Conditions for the MC Mo del When the MC mo del is used , you c an mo del opaque w alls and semi-tr anspar ent walls similar t o the DO mo del (see Wall B oundar y Conditions f or the DO M odel (p.1516 )) with some notable diff erences. 13.3.8.4.1. Opaque Walls 13.3.8.4.2. Semi-T ranspar ent Walls Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1522Modeling H eat Transf er13.3.8.4.1. Opaque Walls In the Radia tion tab of the Wall dialo g box (Figur e 13.27: The Wall D ialog Box for an Opaque Wall with MC M odel (G ray) (p.1523 )), selec t opaque in the BC Type. Figur e 13.27: The Wall D ialo g Box for an Opaque Wall with MC M odel (G ray) For e xternal w alls, you ha ve the option of sp ecifying an e xternal ir radia tion flux b y selec ting Boundar y Sour ce. (Figur e 13.28: The Wall D ialog Box for an Opaque Wall with MC M odel (B oundar y Source) (p.1524 )) 1.Specify the v alue of the ir radia tion flux (in W/m2) under Direct Irradia tion . If the non-gr ay MC mo del is being used , a constan t Direct Irradia tion can b e sp ecified f or each band . 2.Specify the ( X,Y,Z) vector tha t defines the Beam D irection .To mo del an isotr opic sour ce, you must set the Beam D irection to 0,0,0 . 1523Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling R adia tionFigur e 13.28: The Wall D ialo g Box for an Opaque Wall with MC M odel (B oundar y Sour ce) Optionally selec t Polar D istribution F unc tion , which c an b e used if the ir radia tion in tensit y varies with dir ection, but is r otationally symmetr ic ab out a giv en dir ection. For e xample , LED ligh t sour ces. You ha ve the option of sp ecifying a p olar distr ibution via an Expression or Table . If you selec t Expression (Figur e 13.29: The Wall D ialog Box for an Opaque Wall with MC M odel (P olar Distribution with Expr ession) (p.1525 )), enter an e xpression t o define the p olar distr ibution as a func tion of "P olarA ngle". For e xample: cos(PolarAngle) + sin(PolarAngle) The e xpression is e valua ted a t 100 angles b etween 0 and 90 degr ees t o form da ta pairs of Polar Angle and Rela tive In tensit y.You c an wr ite this p olar distr ibution da ta via a .csv file or plot it t o the gr aphics windo w using the Write... and Plot... butt ons, respectively. If you selec t Table (Figur e 13.30: The Wall D ialog Box for an Opaque Wall with MC M odel (P olar Distribution with Table) (p.1526 )), you must manually en ter the da ta pairs or r ead a pr eviously cr eated .csv file. 1.Selec t the Numb er of D ata P airs to define the p olar c oordina te sy stem f or y our ir radia tion sour ce. 2.Enter the da ta pairs in the f orm of Angle and Rela tive In tensit y. Note tha t the minimum numb er of da ta pairs is 2 and must include r elative in tensit y da ta for 0 degr ees. All angles must b e between 0 and 90 degr ees.Rela tive In tensit y is typic ally b etween 0 and 1 although it do es not ha ve to be. A Rela tive In tensit y of z ero at a giv en angle means ther e is no r adia tion in tha t dir ection. 3.You ha ve the option of r eading and wr iting the p olar distr ibution da ta (via .csv files) using the Read ... and Write... butt ons.You c an plot the p olar distr ibution da ta in the gr aphics windo w by selec ting Plot.... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1524Modeling H eat Transf erSpecify the ( X,Y,Z) vector tha t defines the Referenc e D irection .This det ermines the c enter of the polar distr ibution func tion. Figur e 13.29: The Wall D ialo g Box for an Opaque Wall with MC M odel (P olar D istribution with Expression) 1525Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling R adia tionFigur e 13.30: The Wall D ialo g Box for an Opaque Wall with MC M odel (P olar D istribution with Table) You will also b e requir ed t o sp ecify the in ternal emissivit y in the Thermal tab of the Wall dialo g box (Figur e 13.31: The Wall D ialog Box Showing In ternal Emissivit y Thermal C onditions f or an Opaque Wall (G ray) (p.1527 )). For gr ay-radia tion MC mo dels , enter the appr opriate value f or Internal Emissivit y. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1526Modeling H eat Transf erFigur e 13.31: The Wall D ialo g Box Showing In ternal E missivit y Thermal C onditions f or an Opaque Wall (G ray) For the non-gr ay MC mo del, specify a c onstan t Internal E missivit y for each w avelength band in the Radia tion tab of the Wall dialo g box. 1527Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling R adia tionFigur e 13.32: The Wall D ialo g Box for an Opaque Wall with MC M odel (N on-gr ay) You c an also sp ecify the e xternal emissivit y and e xternal r adia tion t emp erature for an e xternal w all when the ther mal c onditions ar e set t o Radia tion or Mixed in the Wall dialo g box (Figur e 13.33: The Wall D ialog Box Showing Ex ternal Emissivit y and Ex ternal R adia tion Temp erature Thermal C ondi- tions (p.1529 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1528Modeling H eat Transf erFigur e 13.33: The Wall D ialo g Box Showing E xternal E missivit y and E xternal R adia tion Temp erature Thermal C onditions Specify the Diffuse F raction , the fr action of the r eflec ted r adia tion fr om the w all tha t is tr eated as diffuse b etween 0 and 1 . By default , the Diffuse F raction is set t o 1, indic ating tha t all of the r adi- ation is diffuse . A diffuse fr action of 0 tr eats the r adia tion as pur ely sp ecular . If you sp ecify a v alue between 0 and 1 , the r adia tion is tr eated as par tially diffuse and par tially sp ecular . If the non-gr ay MC mo del is b eing used , the Diffuse F raction can b e sp ecified f or each band . For mor e inf ormation on b oundar y condition tr eatmen t at opaque w alls (f or the DO mo del), see Boundar y and C ell Z one C ondition Treatmen t at Opaque Walls in the Theor y Guide . 13.3.8.4.2. Semi-T ranspar ent Walls To define r adia tion f or a semi-tr anspar ent wall, click the Radia tion tab in the Wall dialo g box and then selec t semi-tr anspar ent in the BC Type. •For in ternal semi-tr anspar ent walls, specify the Internal E missivit y and Diffuse F raction as descr ibed in Opaque Walls (p.1523 ). •For e xternal semi-tr anspar ent walls, you also ha ve the option of sp ecifying e xternal ir radia tion. –If you enable Boundar y Sour ce and pr ovide a b eam dir ection, as descr ibed in Opaque Walls (p.1523 ), the e xternal ir radia tion is tr eated as dir ectional. –If you sp ecify the e xternal emissivit y and e xternal r adia tion t emp erature for a semi-tr anspar ent wall when the ther mal c onditions ar e set t o Radia tion or Mixed in the Wall dialo g box (Figur e 13.31: The 1529Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling R adia tionWall D ialog Box Showing In ternal Emissivit y Thermal C onditions f or an Opaque Wall (G ray) (p.1527 )), the e xternal ir radia tion is tr eated as diffuse . Imp ortant •Note tha t the r efractive inde x of the e xternal medium is assumed t o be 1. •If Heat Flux conditions ar e sp ecified in the Thermal tab of the Wall dialo g box, the sp ecified heat flux is c onsider ed t o be only the c onduc tion and c onvection p ortion of the b oundar y flux. The giv en ir radia tion sp ecifies the inc oming e xterior r adia tive flux; the r adia tive flux transmitt ed fr om the domain in terior t o the outside is c omput ed as a par t of the c alcula tion by ANSY S Fluen t. Internal emissivit y is ignor ed f or semi-tr anspar ent sur faces. •Note tha t when a b oundar y wall is made semi-tr anspar ent ANSY S Fluen t calcula tes the amoun t of radia tion lea ving as w ell as en tering the domain. If you do not pr ovide a sour ce of ir radia tion or a r adia ting ther mal c ondition (f or e xample Mixed or Radia tion ) then y ou ar e eff ectively radia ting t o a t emp erature of K and it is highly lik ely y ou ma y obser ve temp eratures in y our model tha t are lower than e xpected. Ensur e tha t the e xternal (inc oming) r adian t conditions give go od acc oun t of the sur roundings . •Internal E missivit y is assumed t o be zero for e xternal semi-tr anspar ent walls. For In ternal semi-tr anspar ent walls, internal emissivit y is only r equir ed on w alls b etween fluid and solid zones , or b etween t wo solid z ones . For a detailed descr iption of b oundar y condition tr eatmen t at semi-tr anspar ent walls (f or the DO model), see Cell Z one and B oundar y Condition Treatmen t at Semi-T ranspar ent Walls in the Theor y Guide . 13.3.8.5. Solid C ell Z ones C onditions for the DO or MC Mo dels With the DO or MC mo del, you c an sp ecify whether or not y ou w ant to solv e for radia tion in each cell z one in the domain. By default , the DO or MC equa tions ar e solv ed in all fluid z ones , but not in any solid z ones . If you w ant to mo del semi-tr anspar ent media, for e xample , you c an enable r adia tion in the solid z one(s). To do so , enable the Participa tes In R adia tion option in the Solid dialo g box (Figur e 13.34: The S olid D ialog Box (p.1531 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1530Modeling H eat Transf erFigur e 13.34: The S olid D ialo g Box Imp ortant In gener al, you should not disable the Participa tes In R adia tion option f or an y fluid z ones . See Solid S emi-T ranspar ent Media in the Theor y Guide f or mor e inf ormation on solid semi-tr anspar ent media. 13.3.8.6. Thermal B oundar y Conditions In gener al, any well-p osed c ombina tion of ther mal b oundar y conditions c an b e used when an y of the r adia tion mo dels is ac tive.The r adia tion mo del will b e well-p osed in c ombina tion with fix ed temp erature walls, conduc ting w alls, and/or w alls with set e xternal hea t transf er b oundar y conditions (Thermal B oundar y Conditions a t Walls (p.984)).You c an also use an y of the r adia tion mo dels with heat flux b oundar y conditions defined a t walls, in which c ase the hea t flux y ou define will b e treated as the sum of the c onvective and r adia tive hea t flux es.The e xception t o this is the c ase of semi- transpar ent walls f or the DO mo del. Here, ANSY S Fluen t allo ws you t o sp ecify the c onvective and r a- diative portions of the hea t flux separ ately. 13.3.9. Solution S trategies f or R adia tion M odeling For the P-1, DTRM, S2S, and the DO r adia tion mo dels , ther e ar e se veral par amet ers tha t control the radia tion c alcula tion. You c an use the default solution par amet ers f or most pr oblems , or y ou c an modify these par amet ers t o control the c onvergenc e and accur acy of the solution. Iteration par amet ers that are unique f or a par ticular r adia tion mo del ar e sp ecified in the Radia tion M odel dialo g box (for example ,Energy Iterations p er R adia tion I teration ).Spatial D iscr etiza tion (Discretiza tion in the 1531Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling R adia tionTheor y Guide ) and Under-Relaxa tion F actors (Under-R elaxa tion of Variables in the Theor y Guide ) are specified in the Solution M etho ds and Solution C ontrols task pages , respectively.The Convergenc e Criterion (Modifying C onvergenc e Criteria (p.2654 )) is set in the Residual M onit ors dialo g box. There ar e no solution par amet ers t o be set f or the R osseland mo del, sinc e it impac ts the solution only through the ener gy equa tion. Imp ortant If radia tion is the only mo del b eing solv ed in ANSY S Fluen t and all other equa tions ar e disabled , then the r adia tion tr ansf er equa tion will aut oma tically b e solv ed f or e very iteration, regar dless of wha t the Energy Iterations p er R adia tion I teration field is set t o in the user interface. 13.3.9.1. P-1 Mo del S olution P aramet ers For the P-1 r adia tion mo del, you c an c ontrol the c onvergenc e cr iterion and under-r elaxa tion fac tor. You should also pa y attention t o the optic al thick ness , as descr ibed b elow. The default c onvergenc e cr iterion f or the P-1 mo del is 10-6, the same as tha t for the ener gy equa tion, sinc e the t wo ar e closely link ed. See Monit oring R esiduals (p.2647 ) for details ab out c onvergenc e cr i- teria.You c an set the Convergenc e Criterion for p1 in the Residual M onit ors dialo g box. Solution → Monit ors → Residuals Edit... The under-r elaxa tion fac tor for the P-1 mo del is set with those f or other v ariables , as descr ibed in Setting U nder-R elaxa tion F actors (p.2573 ). Note tha t sinc e the equa tion f or the r adia tion t emp erature (Equa tion 5.21 in the Theor y Guide ) is a r elatively stable sc alar tr ansp ort equa tion, in most c ases y ou can saf ely use lar ge v alues of under-r elaxa tion (0.9–1.0). For optimal c onvergenc e with the P-1 mo del, the optic al thick ness must b e between 0.01 and 10 (pr eferably not lar ger than 5). Smaller optic al thick nesses ar e typic al for v ery small enclosur es (char acteristic siz e of the or der of 1 cm), but f or such pr oblems y ou c an saf ely incr ease the absor ption coefficien t to a v alue f or which . Incr easing the absor ption c oefficien t will not change the ph ysics of the pr oblem b ecause the diff erence in the le vel of tr anspar ency of a medium with optic al thick ness = 0.01 and one with optic al thick ness <0.01 is indistinguishable within the accur acy level of the c omputa tion. 13.3.9.2. DTRM S olution P aramet ers When the DTRM is ac tive, ANSY S Fluen t up dates the r adia tion field dur ing the c alcula tion and c omput es the r esulting ener gy sour ces and hea t flux es via the r ay-tracing t echnique descr ibed in Ray Tracing in the Theor y Guide . ANSY S Fluen t provides se veral solution par amet ers in the e xpanded p ortion of the Radia tion M odel dialo g box (Figur e 13.35: The R adia tion M odel D ialog Box (DTRM) (p.1533 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1532Modeling H eat Transf erFigur e 13.35: The R adia tion M odel D ialo g Box (DTRM) You c an c ontrol the maximum numb er of it erations of the r adia tion c alcula tion dur ing each global iteration b y changing the Maximum N umb er of R adia tion I terations .The default setting of 5 means that the r adiosit y will b e up dated up t o 5 times .The ac tual numb er of it erations will b e less if the residual c onvergenc e cr iterion is e xceeded a t an y point dur ing these it erations . The Residual C onvergenc e Criteria par amet er (0.001 b y default) det ermines when the r adia tion in- tensit y up date is c onverged . It is defined as the maximum nor maliz ed change in the sur face in tensit y from one DTRM r adia tion it eration t o the ne xt (see Equa tion 13.9 (p.1535 )). You c an also c ontrol the fr equenc y tha t the r adia tion field is up dated as the c ontinuous phase solution proceeds .The Energy Iterations p er R adia tion I teration par amet er is set t o 10 b y default. This means tha t the r adia tion c alcula tion is p erformed onc e every 10 it erations of the solution pr ocess. Increasing the numb er can sp eed the c alcula tion pr ocess, but ma y slo w overall c onvergenc e. 1533Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling R adia tion13.3.9.3. S2S S olution P aramet ers For the S2S mo del, as f or the DTRM, you c an c ontrol the fr equenc y with which the r adiosit y is up dated as the c ontinuous-phase solution pr oceeds . See the pr evious descr iption of Energy Iterations p er Radia tion I teration . If you ar e using the pr essur e-based solv er and y ou first solv e the flo w equa tions with the ener gy equa tion tur ned off , you should r educ e the Energy Iterations p er R adia tion I teration from 10 t o 1 or 2. This will ensur e the c onvergenc e of the r adiosit y. If the default v alue of 10 is k ept in this c ase, it is p ossible tha t the flo w and ener gy residuals ma y converge and the solution will t ermina te before the r adiosit y is c onverged . See Residual R eporting f or the S2S M odel (p.1535 ) for mor e inf ormation about r esiduals f or the S2S mo del. You c an c ontrol the maximum numb er of it erations of the r adia tion c alcula tion dur ing each global iteration b y changing the Maximum N umb er of R adia tion I terations .The default setting of 5 means that the r adiosit y will b e up dated up t o 5 times .The ac tual numb er of it erations will b e less if the residual c onvergenc e cr iterion is e xceeded a t an y point dur ing these it erations . The Residual C onvergenc e Criteria (0.001 b y default) det ermines when the r adiosit y up date is c on- verged . It is defined as the maximum nor maliz ed change in the r adiosit y from one S2S r adia tion it er- ation t o the ne xt (see Equa tion 13.10 (p.1536 )). 13.3.9.4. DO S olution P aramet ers For the discr ete or dina tes mo del, as f or the DTRM, you c an c ontrol the fr equenc y tha t the sur face intensit y is up dated as the c ontinuous phase solution pr oceeds thr ough the Energy Iterations p er Radia tion I teration setting . See the descr iption of DTRM S olution P aramet ers (p.1532 ). For most pr oblems , the default under-r elaxa tion of 1.0 f or the DO equa tions is adequa te. For pr oblems with lar ge optic al thick nesses ( ), you ma y experienc e slo w convergenc e or solution oscilla tion. For such c ases , under-r elaxing the ener gy and DO equa tions is useful. Under-r elaxa tion fac tors b etween 0.9 and 1.0 ar e recommended f or b oth equa tions . 13.3.9.5. MC S olution P aramet ers For the MC mo del, as f or the DTRM, you c an c ontrol the fr equenc y tha t the sur face in tensit y is up dated as the c ontinuous phase solution pr oceeds thr ough the Energy Iterations p er R adia tion I teration setting . See the descr iption of DTRM S olution P aramet ers (p.1532 ). Wall Irradiation Flux.Normalized Std Deviation and Radiation Intensity.Nor- malized Std Deviation (both a vailable dur ing p ostpr ocessing) c an giv e an indic ation of the qualit y of the solution. They ar ise fr om the st ochastic na ture of the M onte Carlo mo del. •Wall Irradiation Flux.Normalized Std Deviation is the maximum nor maliz ed standar d deviation of the ir radia tion flux a t an elemen t fac e on a b oundar y.The pr esenc e of small isola ted b oundar y regions with v alues of Wall Irradiation Flux.Normalized Std Deviation larger than 30% is an indic ation tha t the elemen t fac es in those r egions w ere insufficien tly sampled . Incr easing the Target Numb er of Hist ories may help addr ess this , at the e xpense of c omputa tional eff ort. •Radiation Intensity.Normalized Std Deviation is the maximum nor maliz ed standar d deviation of the r adia tion in tensit y within an elemen t.The v alue of Radiation Intensity.Normal- ized Std Deviation is e xpected t o be less than 30% within a r eliable r adia tion field solution. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1534Modeling H eat Transf erBecause of the st ochastic b ehavior, it c an b e difficult t o judge the c onvergenc e of MC r adia tion c ases based on r esiduals alone , par ticular ly if the standar d de viations ar e lar ge. It is r ecommended tha t you create a t emp erature pr obe (for e xample , a Surface Rep ort Definition ) and monit or its stabilit y during the solution. For mor e inf ormation, see Creating R eport Definitions (p.2910 ). 13.3.9.6. Running the C alculation Onc e the r adia tion pr oblem has b een set up , you c an pr oceed as usual with the c alcula tion. Note that while the P-1 and DO mo dels will solv e additional tr ansp ort equa tions and r eport residuals , the DTRM and the R osseland and S2S mo dels will not (sinc e the y impac t the solution only thr ough the ener gy equa tion). Residuals f or the DTRM and S2S mo del r adia tion it erations ar e reported b y ANSY S Fluen t every time such an it eration is p erformed , as descr ibed b elow. When r unning the S2S mo del with the par allel solv er, not e tha t coupled w alls ar e enc apsula ted, which may cause pr oblems with the par titioning of the mesh. See Troublesho oting (p.3093 ) for recommend- ations on c orrecting such pr oblems . 13.3.9.6.1. Residual R eporting for the P -1 Mo del The r esidual f or radia tion as c alcula ted b y the P-1 mo del is up dated af ter each it eration and r eported with the r esiduals f or all other v ariables . ANSY S Fluen t reports the nor maliz ed P-1 r adia tion r esidual as defined in Monit oring R esiduals (p.2647 ) for the other tr ansp ort equa tions . 13.3.9.6.2. Residual R eporting for the DO Mo del After each DO it eration, the DO mo del r eports a c omp osite nor maliz ed r esidual f or all the DO transp ort equa tions .The definition of the r esiduals is similar t o tha t for the other tr ansp ort equa tions (see Monit oring R esiduals (p.2647 )). 13.3.9.6.3. Residual R eporting for the DTRM ANSY S Fluen t do es not include a DTRM r esidual in its usual r esidual r eport tha t is issued af ter each iteration. The eff ect of r adia tion on the solution c an b e ga ther ed, inst ead, via its impac t on the ener gy field and the ener gy residual. However, each time a DTRM it eration is p erformed , ANSY S Fluen t will print out the nor maliz ed r adia tion er ror for each DTRM r adia tion it eration. The nor maliz ed r adia tion error is defined as (13.9) wher e the er ror is the maximum change in the in tensit y ( ) at the cur rent radia tion it eration, normaliz ed b y the maximum sur face emissiv e power, and is the t otal numb er of r adia ting sur faces. Note tha t the default r adia tion c onvergenc e cr iterion, as not ed in DTRM S olution P aramet ers (p.1532 ), defines the r adia tion c alcula tion t o be converged when decr eases t o or less . 13.3.9.6.4. Residual R eporting for the S2S Mo del ANSY S Fluen t do es not include an S2S r esidual in its usual r esidual r eport tha t is issued af ter each iteration. The eff ect of r adia tion on the solution c an b e ga ther ed, inst ead, via its impac t on the ener gy field and the ener gy residual. However, each time an S2S it eration is p erformed , ANSY S Fluen t will print out the nor maliz ed r adia tion er ror for each S2S r adia tion it eration. The nor maliz ed r adia tion error is defined as 1535Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling R adia tion(13.10) wher e the er ror is the maximum change in the r adiosit y ( ) at the cur rent radia tion it eration, normaliz ed b y the maximum sur face emissiv e power, and is the t otal numb er of r adia ting sur face clust ers. Note tha t the default r adia tion c onvergenc e cr iterion, as not ed in DTRM S olution P aramet- ers (p.1532 ), defines the r adia tion c alcula tion t o be converged when decr eases t o or less . 13.3.9.6.5. Disabling the Up dat e of the R adiation F luxes Sometimes , you ma y want to set up y our ANSY S Fluen t mo del with the r adia tion mo del ac tive and then disable the r adia tion c alcula tion dur ing the initial c alcula tion phase . For the P-1 and DO mo dels , you c an tur n off the r adia tion c alcula tion t emp orarily b y deselec ting P1 or Discr ete Or dina tes in the Equa tions dialo g box, which is acc essed b y right-click ing Solution C ontrols in the tr ee (under Solution ) and click ing Equa tions ... in the menu tha t op ens. For the DTRM and the S2S mo del, ther e is no r adia tion c alcula tion t o disable in the Equa tions dialo g box.You c an inst ead set a v ery lar ge numb er for Energy Iterations p er R adia tion I teration in the Iteration P aramet ers group b ox of the Radia tion M odel dialo g box. If you tur n off the r adia tion c alcula tion, ANSY S Fluen t will sk ip the up date of the r adia tion field during subsequen t iterations , but will lea ve in plac e the influenc e of the cur rent radia tion field on ener gy sour ces due t o absor ption, wall hea t flux es, and so on. Turning the r adia tion c alcula tion off in this w ay can ther efore be used t o initia te your mo deling w ork with the r adia tion mo del inac tive and/or t o focus the c omputa tional eff ort on the other equa tions if the r adia tion mo del is r elatively well c onverged . 13.3.10. Postpr ocessing R adia tion Q uan tities Information r egar ding p ostpr ocessing r adia tion quan tities c an b e found in the f ollowing sec tions: 13.3.10.1. Available Variables f or P ostpr ocessing 13.3.10.2. Reporting R adia tive Heat Transf er Through B oundar ies 13.3.10.3. Overall H eat Balanc es When U sing the DTRM 13.3.10.4. Displa ying R ays and C lusters f or the DTRM 13.3.10.5. Reporting R adia tion in the S2S M odel 13.3.10.1. Available Variables for P ostpr ocessing ANSY S Fluen t provides r adia tion quan tities tha t you c an use in p ostpr ocessing when y our mo del in- cludes the solution of r adia tive hea t transf er.You c an gener ate gr aphic al plots or alphanumer ic reports of the f ollowing v ariables/func tions: In the Radia tion... categor y: •Inciden t Radia tion (P-1, DO, and MC mo dels) •Inciden t Radia tion (B and n) (non-gr ay P-1, non-gr ay DO , non-gr ay MC mo dels) •Absor ption C oefficien t (DTRM, P-1, DO, and R osseland mo dels) •Scattering C oefficien t (P-1, DO, and R osseland mo dels) •Refr active Inde x (P–1, DO, and R osseland mo dels) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1536Modeling H eat Transf er•Radia tion Temp erature (P-1, DO, and MC mo dels) •Surface Clust er ID (S2S mo del) •Volumetr ic A bsorb ed R adia tion (P-1, DO, and MC mo dels) •Volumetr ic Emitt ed R adia tion (P-1, DO, and MC mo dels) •Radia tion In tensit y.Normaliz ed S td D eviation (MC mo del) •Wall Ir radia tion F lux.N ormaliz ed S td D eviation (MC mo del) In the Wall F luxes... categor y: •Radia tion H eat Flux (all r adia tion mo dels) •Surface Inciden t Radia tion (S2S, DTRM, and DO mo dels) •Absorb ed R adia tion F lux (DO mo del, semi-tr anspar ent wall) •Reflec ted R adia tion F lux (DO mo del, semi-tr anspar ent wall) •Transmitt ed R adia tion F lux (DO mo del, semi-tr anspar ent wall) •Beam Ir radia tion F lux (DO mo del, semi-tr anspar ent wall) See Field F unction D efinitions (p.2959 ) for definitions of these p ostpr ocessing v ariables . Note tha t in addition, inciden t radia tion, transmitt ed, reflec ted and absorb ed r adia tion flux ar e also a vailable on a per-band basis f or the non-gr ay DO mo del. Imp ortant •The sign c onvention on the r adia tive hea t flux is such tha t the hea t flux fr om the w all sur face is a p ositiv e quan tity. •It is p ossible t o export hea t flux da ta on w all z ones (including r adia tion) t o a gener ic file tha t you c an e xamine or use in an e xternal pr ogram. See Exporting H eat Flux D ata (p.1475 ) for details . •Take care not t o confuse Inciden t Radia tion and Surface Inciden t Radia tion .Inciden t Radi- ation is a v olumetr ic quan tity giving the t otal r adian t load passing thr ough the c ell (in all dir- ections), wher eas Surface Inciden t Radia tion is the t otal r adian t load hitting the sur face (which will subsequen tly b e absorb ed, transmitt ed and r eflec ted). There is no dir ect means t o report how much r adia tion has b een absorb ed/emitt ed/sc attered in c ells. 13.3.10.2. Reporting R adiativ e Heat Transfer Through B oundaries You c an use the Flux Rep orts dialo g box to comput e the r adia tive hea t transf er thr ough each boundar y of the domain, or t o sum the r adia tive hea t transf er thr ough all b oundar ies. Results → Rep orts → Fluxes Edit... See Fluxes Through B oundar ies (p.2937 ) for details ab out gener ating flux r eports. 1537Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling R adia tion13.3.10.3. Overall H eat B alanc es When Using the DTRM The DTRM yields a global hea t balanc e and a balanc e of r adian t hea t flux es only in the limit of a sufficien t numb er of r ays. In an y giv en c alcula tion, ther efore, if the numb er of r ays is insufficien t you may find tha t the r adian t flux es do not ob ey a str ict balanc e. Such imbalanc es ar e the ine vitable consequenc e of the discr ete ray tracing pr ocedur e and c an b e minimiz ed b y selec ting a lar ger numb er of rays from each w all b oundar y. 13.3.10.4. Displa ying R ays and C lust ers for the DTRM When y ou use the DTRM, ANSY S Fluen t allo ws you t o displa y sur face or v olume clust ers, as w ell as the r ays tha t emana te from a par ticular sur face clust er.You c an use the DTRM G raphics dialo g box (Figur e 13.36: The DTRM G raphics D ialog Box (p.1538 )) for all of these displa ys. Results → Model S pecific → DTRM G raphics ... Figur e 13.36: The DTRM G raphics D ialo g Box 13.3.10.4.1. Displa ying C lust ers To view clust ers, selec t Clust er under Displa y Type and then selec t either Surface or Volume under Clust er Type. To displa y all of the sur face or v olume clust ers, selec t the Displa y All Clust ers option under Clust er Selec tion and click the Displa y butt on. To displa y only the clust er (sur face or v olume) near est t o a sp ecified p oint, deselec t the Displa y All Clust ers option and sp ecify the c oordina tes under Nearest P oint.You ma y also use the mouse t o choose the near est p oint. Click the Selec t Point With M ouse butt on and then r ight-click a p oint in the gr aphics windo w. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1538Modeling H eat Transf er13.3.10.4.2. Displa ying R ays To displa y the r ays emana ting fr om the sur face clust er near est t o the sp ecified p oint, selec t Ray under Displa y Type. Set the appr opriate values f or Theta and Phi D ivisions under Ray Paramet ers (see Setting U p the DTRM (p.1492 ) for details), and then click the Displa y butt on.Figur e 13.37: Ray Displa y (p.1539 ) sho ws a r ay plot f or a simple 2D geometr y. Figur e 13.37: Ray D ispla y 13.3.10.4.3. Including the Mesh in the D ispla y For some pr oblems , esp ecially c omple x 3D geometr ies, you ma y want to include p ortions of the mesh in y our r ay or clust er displa y as spa tial r eference points. For e xample , you ma y want to sho w the lo cation of an inlet and an outlet along with displa ying the r ays.This is acc omplished b y enabling the Draw M esh option in the DTRM G raphics dialo g box.The Mesh D ispla y dialo g box will app ear automa tically when y ou enable the Draw M esh option, and y ou c an set the mesh displa y par amet ers ther e.When y ou click Displa y in the DTRM G raphics dialo g box, the mesh displa y, as defined in the Mesh D ispla y dialo g box, will b e included in the r ay or clust er displa y. 13.3.10.5. Reporting R adiation in the S2S Mo del When y ou use the S2S mo del, ANSY S Fluen t allo ws you t o view the v alues of the view fac tor and r a- diation emitt ed fr om one z one t o an y other z one .You c an use the S2S Inf ormation dialo g box (Figur e 13.38: The S2S Inf ormation D ialog Box (p.1540 )) to gener ate a r eport of these v alues in the console or as a separ ate file . Results → Model S pecific → S2S Inf ormation... 1539Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling R adia tionFigur e 13.38: The S2S Inf ormation D ialo g Box The st eps f or gener ating the r eport are as f ollows: 1.Specify the v alues in which y ou ar e interested b y selec ting View Factors and/or Inciden t Radia tion . 2.Choose the z ones f or which y ou w ould lik e da ta b y selec ting them in the lists under From and To (at least one z one must b e selec ted under each list). To selec t all of the z ones of a par ticular t ype, click tha t categor y in the list under Boundar y Types. 3.Specify ho w you w ould lik e to pr esen t the da ta.To report the v alues in the c onsole , click the Comput e butt on.To wr ite the da ta as an S2S Inf o File (.sif format), click the Write... butt on and en ter a file name in The S elec t File D ialog Box (p.569). The f ollowing is an e xample of ho w the da ta is pr esen ted: S2S Information From wall1 to: View factor Incident Radiation wall1 0.0000 0.0000 wall2 0.2929 171387.7813 wall3 0.2929 155305.7969 wall4 0.4142 29055.9023 From wall2 to: View factor Incident Radiation wall1 0.2929 306451.9688 wall2 0.0000 0.0000 wall3 0.4142 214195.0938 wall4 0.2929 19153.2715 Note tha t the header list ed ab ove (S2S Information ) is not displa yed in the c onsole . 13.3.11. Solar L oad M odel ANSY S Fluen t provides a solar load mo del tha t can b e used t o calcula te radia tion eff ects fr om the sun ’s rays tha t en ter a c omputa tional domain. Two options ar e available f or the mo del: Solar R ay Tracing and Solar Ir radia tion .The S olar R ay Tracing appr oach is a highly efficien t and pr actical means of ap- plying solar loads as hea t sour ces in the ener gy equa tions . In c ases wher e you w ant to use the DO or MC mo del t o calcula te radia tion eff ects within the domain, the S olar Ir radia tion option is a vailable t o supply outside b eam dir ection and in tensit y par amet ers dir ectly t o the r adia tion mo del. The solar load model includes a solar c alcula tor utilit y tha t can b e used t o constr uct the sun ’s location in the sk y for Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1540Modeling H eat Transf era giv en time-of-da y, date, and p osition. Solar load is a vailable in the 3D solv er only , and c an b e used to mo del st eady and unst eady flo ws. 13.3.11.1. Intr oduc tion Typic al applic ations tha t are well-suit ed f or solar load simula tions include the f ollowing: •automotiv e clima te control (A CC) applic ations •human c omf ort mo deling applic ations in buildings The eff ects of solar loading ar e needed in man y ACC applic ations , wher e the t emp erature, humidit y, and v elocity fields ar ound passengers (and dr ivers) ar e desir ed. ACC sy stems ar e tested f or their c apacit y to cool do wn passenger c ompar tmen ts af ter the y ha ve been “soak ed” in in tense solar r adia tion. ANSY S Fluen t’s solar load mo del will enable y ou t o simula te solar loading eff ects and pr edic t the time it will take to reasonably c ool do wn the c abin of a c ar tha t has b een e xposed t o solar r adia tion, as w ell as predic t the time in terval needed t o lo wer the t emp erature in sp ecified p oints and ar eas within the domain. In the analy sis of buildings , solar loading pr ovides a signific ant bur den on the c ooling r equir emen t in w arm clima tes, par ticular ly wher e ar chitects w ant to use the aesthetics of glaz ed fac ades . Even in cooler clima tes, solar loading c an pr ovide a bur den dur ing w armer seasons wher e mo dern buildings are well insula ted against ther mal loss dur ing win ter mon ths. As well as pr oviding an engineer with a pr actical tool for det ermining the solar hea ting eff ect inside a building , ANSY S Fluen t’s solar load model will allo w the solar tr ansmission thr ough all glaz ed sur faces to be det ermined o ver the c ourse of a da y, allo wing imp ortant decisions t o be made b efore under taking an y flo w studies . ANSY S Fluen t’s solar load mo del also allo ws you t o simula te porous blinds , which c an tr ansmit a p ortion of the solar radia tion while also allo wing fluid flo w. 13.3.11.2. Solar R ay Tracing The solar load mo del’s ray tracing algor ithm c an b e used t o pr edic t the dir ect illumina tion ener gy sour ce tha t results fr om inciden t solar r adia tion. It tak es a b eam tha t is mo deled using the sun p osition vector and illumina tion par amet ers, applies it t o an y or all w all, porous jump , and inlet/outlet boundar y zones tha t you sp ecify , performs a fac e-by-fac e shading analy sis t o det ermine w ell-defined shado ws on all b oundar y fac es and in terior w alls, and c omput es the hea t flux on the b oundar y fac es that results fr om the inciden t radia tion. Imp ortant The solar r ay tracing mo del includes only b oundar y zones tha t are adjac ent to fluid z ones in the r ay tracing c alcula tion. Therefore, boundar y zones tha t are attached t o solid z ones are treated as tr anspar ent and ar e not included in the r ay tracing algor ithm. The r esulting hea t flux tha t is c omput ed b y the solar r ay tracing algor ithm is c oupled t o the ANSY S Fluen t calcula tion via a sour ce term in the ener gy equa tion. The hea t sour ces ar e added dir ectly t o computa tional c ells b ordering each fac e and ar e assigned t o adjac ent cells in the f ollowing or der: shell c onduc tion c ells, solid c ells, and fluid c ells. Heat sour ces ar e assigned t o one of these t ypes of adjac ent cells, only .You c an cho ose t o override this or der and include adjac ent fluid c ells in the solar load c alcula tion b y issuing a c ommand in the t ext user in terface (see Text Interface-Only C om- mands (p.1561 ) for details). Note tha t the sun p osition v ector and solar in tensit y can b e en tered either directly b y you or c omput ed fr om the solar c alcula tor. Direct and diffuse ir radia tion par amet ers c an 1541Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling R adia tionalso b e sp ecified using a user-defined func tion (UDF) and ho oked t o ANSY S Fluen t in the Radia tion Model dialo g box. The solar r ay tracing option allo ws you t o include the eff ects of dir ect solar illumina tion as w ell as diffuse solar r adia tion in y our ANSY S Fluen t mo del. A two-band sp ectral mo del is used f or dir ect solar illumina tion and acc oun ts for separ ate ma terial pr operties in the visible and infr ared bands . A single- band hemispher ical-averaged sp ectral mo del is used f or diffuse r adia tion. Opaque ma terials ar e char acterized in t erms of t wo-band absor ptivities . A semi-tr anspar ent ma terial requir es sp ecific ation of absor ptivit y and tr ansmissivit y.Values tha t you sp ecify f or tr ansmissivit y and absor ptivit y are defined f or nor mal inciden t rays. ANSY S Fluen t recomput es/in terpolates these v alues f or the giv en angle of incidenc e. The solar r ay tracing algor ithm also acc oun ts for in ternal sc attered and diffusiv e loading .The r eflec ted comp onen t of dir ect solar ir radia tion is tr acked. A fr action of this r adia tive hea t flux, called in ternally scattered ener gy is applied t o all the sur faces par ticipa ting in the solar load c alcula tion, weigh ted b y area.The in ternally sc attered ener gy dep ends on the sc attering fr action tha t is sp ecified in the TUI, whose default v alue is . Depending on the r eflec tivit y of the pr imar y sur face, the sc attering fr action can b e responsible f or the inclusion (or e xclusion) of a lar ge amoun t of r adia tion within the r est of the domain. Also included as in ternally sc attered ener gy is the c ontribution of the tr ansmitt ed c omp onen t of diffuse solar ir radia tion (which en ters a domain thr ough semi-tr anspar ent walls dep ending up on the hemi- spher ical tr ansmissivit y).The t otal v alue of in ternally sc attered ener gy is r eported t o the ANSY S Flu- ent console .The ambien t flux is obtained b y dividing the in ternally sc attered ener gy by the t otal surface ar ea of the fac es par ticipa ting in the solar load c alcula tion. Note tha t Solar R ay Tracing is not a par ticipa ting r adia tion mo del. It do es not deal with emission from sur faces, and the r eflec ting c omp onen t of the pr imar y inciden t load is distr ibut ed unif ormly across all sur faces rather than b eing lo cal to the sur faces reflec ted t o. If sur face emission is an imp ortant factor in y our c ase then y ou c an c onsider implemen ting a r adia tion mo del (f or e xample , P-1) in c on- junc tion with Solar R ay Tracing . Note the f ollowing limita tion when using the solar r ay tracing mo del: •Non-c onformal in terfaces ar e not supp orted with the solar r ay tracing mo del. 13.3.11.2.1. Shading A lgorithm The shading c alcula tion tha t is used f or solar r ay tracing is a str aigh tforward applic ation of v ector geometr y. A ray is tr aced fr om the c entroid of a t est fac e in the dir ection of the sun. Every other face is check ed t o det ermine if the r ay intersec ts the c andida te fac e and if the c andida te fac e is in front of the t est fac e. If both c onditions ar e met , then an opaque fac e complet ely shades the t est face. A semi-tr anspar ent fac e attenua tes the inciden t ener gy. A Barycentric coordina te formula tion is used t o constr uct triangle-r ay intersec tions . A quadr ilateral ray intersec tion metho d is used t o handle the c ase when mo del sur faces c ontain quadr ilaterals. A quad-tr ee pr eprocessing st ep is applied t o reduc e the r ay tracing algor ithm c omple xity tha t can lead to long r un times f or faces and gr eater.The quad-tr ee r efinemen t fac tor c an b e mo dified in the text interface.The default v alue of this par amet er is , which is sufficien t to cover the en tire sp ectrum of mesh siz es b etween one c ell and fiv e million c ells. If the mesh is gr eater than fiv e million c ells, an incr ease in this par amet er w ould r educ e the CPU time needed t o comput e the solar loads . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1542Modeling H eat Transf er13.3.11.2.2. Glazing M aterials Inciden t solar r adia tion c an b e applied t o glass and plastic glazing ma terials of v arious t ypes a t wall boundar ies, and the eff ects of c oated glazings mo deled using the solar r ay tracing algor ithm. To model solar optic al pr operties, you will need t o sp ecify the tr ansmissivit y and r eflec tivit y of the material in the Wall boundar y conditions dialo g box.You c an obtain these v alues fr om the glass (or plastic) manufac turer or use da ta fr om another sour ce (for e xample , ASHR AE Handb ook). Glazing optic al pr operties ar e dep enden t on inciden t angle , and the v ariation is signific ant for an inciden t angle gr eater than degr ees. As the inciden t angle incr eases fr om z ero, transmissivit y decr eases , reflec tivit y incr eases , and absor ptivit y incr eases initially due t o lengthened optic al pa th, and then decr eases as mor e inciden t radia tion is r eflec ted.The shap e of the pr operty cur ve varies with glass t ype and thick ness .This diff erence is mor e pr onounc ed f or c oated glass or f or a multiple- pane glazing sy stem. It cannot b e assumed tha t all glazing sy stems ha ve a univ ersal angular dep end- ence. For c oated glazings , the sp ectral tr ansmissivit y and r eflec tivit y at an y inciden t angle ar e appr oxima ted in the solar load mo del fr om the nor mal angle of incidenc e [34] (p.4006 ). Transmissivit y is giv en b y (13.11) wher e (13.12) Reflec tivit y is giv en b y (13.13) wher e (13.14) The c onstan ts used in Equa tion 13.11 (p.1543 ) and Equa tion 13.13 (p.1543 ) are for c oated glazings and are tak en fr om F inlayson and A rasteh. [34] (p.4006 ).The nor mal tr ansmissivit y and r eflec tivit y, and are sp ecified in the Wall boundar y conditions dialo g box. 13.3.11.2.3. Inputs The f ollowing inputs ar e requir ed f or the solar r ay tracing algor ithm: •sun dir ection v ector •direct solar ir radia tion •diffuse solar ir radia tion •spectral fraction •direct and IR absor ptivit y (opaque w all) •direct and IR absor ptivit y and tr ansmissivit y (semi-tr anspar ent wall and p orous jump) •diffuse hemispher ical absor ptivit y and tr ansmissivit y (semi-tr anspar ent wall) 1543Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling R adia tion•solar tr ansmissivit y fac tor •quad tr ee refinemen t fac tor •scattering fr action •ground r eflec tivit y The sun dir ection v ector is the dir ection v ector lo oking t o the sun, from which the dir ect irradia tion will b e inciden t.You c an en ter the v ector c omp onen ts (X,Y,Z) and the dir ect and diffuse solar ir ra- diation flux es in the Radia tion M odel dialo g box, or y ou c an ha ve these par amet ers der ived fr om the solar c alcula tor.These ir radia tion flux es c an also b e sp ecified using a user-defined func tion ( User- Defined F unctions (UDFs) f or S olar L oad (p.1548 )).The sp ectral fr action is the final input in the Radi- ation M odel dialo g box.This defines the split of visible and infr a-red (shor twave and longw ave re- spectively) r adia tion, specific ally the fr action of the dir ect irradia tion flux tha t is in the visible band . These quan tities c an also b e defined thr ough the t ext interface. The sc attering fr action defines the amoun t of non-absorb ed r adia tion tha t will b e distr ibut ed (uni- formly) acr oss all par ticipa ting sur faces.This is r equir ed as the solar load mo del do es not tr ack the rays beyond the first opaque sur face.Therefore, a highly glaz ed spac e wher e inciden t radia tion is likely t o be reflec ted back out will ha ve a lo w value . Conversely , a pr edominan tly opaque (w all- bounded) spac e wher e reflec ted r adia tion is lik ely t o be inciden t up on (and ultima tely absorb ed b y) other opaque sur faces will ha ve a high v alue .This par amet er is defined thr ough the t ext interface only , tak ing a default v alue of 1.0: define → models → radiation → solar-parameters → scattering-fraction The gr ound r eflec tivit y is used b y the solar c alcula tor to comput e the back ground diffuse r adia tion intensit y comp onen t contribut ed t o by radia tion r eflec ted off the gr ound .This should b e based on typic al figur es for the sur face reflec tivit y of the outside gr ound sur faces. By default this is set t o 0.2, but c an b e adjust ed thr ough the t ext-interface: define → models → radiation → solar-parameters → ground-reflectivity The quad-tr ee-r efinemen t par amet er det ermines the le vel of detail used b y the shading algor ithm. By default this is set t o 7 which will gener ally w ork well, but c an lie b etween 0 and 10. This is defined only thr ough the t ext interface: define → models → radiation → solar-parameters → quad-tree-refinement Further details on the t ext interface-only en tries is pr ovided la ter in this sec tion (see Text Interface- Only C ommands). The absor ptivit y and tr ansmissivit y par amet ers r elated t o a w all or p orous jump ar e en tered in the Wall (under the Radia tion tab) or Porous Jump boundar y condition dialo g box, respectively, for the par ticular b oundar y zones y ou w ant to par ticipa te in solar r ay tracing . On flo w b oundar ies y ou have a solar tr ansmissivit y fac tor to allo w you t o attenua te the inc oming solar flux, for e xample , set to 1 f or a fully op en inlet or set t o 0 f or a ligh t obscur ing louv ered inlet. 13.3.11.3. Solar Irr adiation The solar load mo del’s Solar Ir radia tion option pr ovides y ou with an easy means of applying a solar load dir ectly t o the DO or MC mo del. Unlike the r ay tracing solar load option, the S olar Ir radia tion metho d do es not c omput e hea t flux es and apply them as hea t sour ces to the ener gy equa tion. Inst ead, Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1544Modeling H eat Transf erthe ir radia tion flux is applied dir ectly t o semi-tr anspar ent walls (which y ou sp ecify) as a b oundar y condition, and the r adia tive hea t transf er is der ived fr om the solution of the r adia tion mo del itself . The f ollowing inputs ar e requir ed f or S olar Ir radia tion a t semi-tr anspar ent walls: •direct irradia tion •diffuse ir radia tion (not a vailable f or MC mo del) •beam dir ection •beam width (only r equir ed f or DO mo del) •diffuse fr action In the Wall boundar y condition dialo g box for each semi-tr anspar ent wall y ou w ant to par ticipa te in Solar Ir radia tion, you c an sp ecify tha t the b eam dir ection, direct irradia tion, and diffuse ir radia tion b e derived fr om the solar par amet ers (f or e xample , solar c alcula tor) tha t you set (or c omput e) in the Radia tion M odel dialo g box.This is done b y check ing the Use B eam D irection fr om S olar L oad Model S ettings and Use Ir radia tion fr om S olar L oad M odel S ettings boxes.When selec ted, ANSY S Fluen t sets the b eam width (the angle subt ended b y the sun) t o the default v alue of degr ees when using the DO mo del. Imp ortant Note tha t the sign of the b eam dir ection tha t is needed f or the DO or MC mo del is opp osite the sun dir ection v ector tha t is en tered or der ived fr om the solar par amet ers.The b eam direction in the DO or MC mo del is the dir ection of e xternal r adia tion (f or e xample , radia tion coming fr om the sun), while the sun dir ection v ector in the solar load mo del p oints to the sun. 13.3.11.4. Solar C alculat or ANSY S Fluen t provides a solar c alcula tor tha t can b e used t o comput e solar b eam dir ection and ir ra- diation f or a giv en time , date, and p osition. These v alues c an b e used as inputs t o the solar r ay tracing algor ithm or as semi-tr anspar ent wall b oundar y conditions f or solar ir radia tion. 13.3.11.4.1. Inputs/O utputs Inputs needed f or the solar c alcula tor ar e: •global p osition (la titude , longitude , time z one) •starting da te and time •mesh or ientation •solar ir radia tion metho d •sunshine fac tor Global p osition c onsists of la titude , longitude , and time z one (r elative to GMT ).The time of da y for a transien t simula tion is the star ting time plus the flo w-time . For mesh or ientation, you will need t o specify the N orth and E ast dir ection v ector in the CFD mesh. The default solar ir radia tion metho d is 1545Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling R adia tionFair Weather C onditions . Alternatively, you c an cho ose the Theor etical M aximum metho d.The sunshine factor is simply a linear r educ tion fac tor for the c omput ed inciden t load tha t allo ws for cloud c over to be acc oun ted f or, if appr opriate. You c an sp ecify these inputs in the Solar C alcula tor dialo g box tha t is acc essible fr om the Radia tion Model dialo g box (Figur e 13.42: The S olar C alcula tor D ialog Box (p.1553 )). Alternatively, you c an en ter the par amet ers using t ext interface commands ( Additional Text Interface Commands (p.1563 )). The f ollowing v alues ar e comput ed b y the solar c alcula tor and ar e displa yed in the c onsole whene ver the solar c alcula tor is used: •sun dir ection v ector •sunshine fr action •direct nor mal solar ir radia tion a t ear th’s sur face •diffuse solar ir radia tion - v ertical and hor izontal sur face •ground r eflec ted (diffuse) solar ir radia tion - v ertical sur face Direct nor mal solar ir radia tion is c omput ed using the ASHR AE F air Weather C onditions metho d, when this option is selec ted in the solar c alcula tor. Note: Equa tion 20 and Table 7 fr om C hapt er 30 of the 2001 ASHR AE Handb ook of F undamen tals.The theor etical maximum v alues f or dir ect nor mal solar ir radia tion and diffuse solar ir radia tion ar e comput ed using NREL ’s Theor etical M aximum metho d, when this option is selec ted. In pr actice, these v alues ar e unlik ely t o be experienc ed due to atmospher ic conditions . ANSY S Fluen t comput es the diffuse solar ir radia tion c omp onen ts (v ertical and hor izontal) in ternally for each fac e in the domain. When the Theor etical M aximum metho d is chosen, these diffuse ir radi- ation v alues pr ovide estima tes for the maximum v ertical and hor izontal sur face eff ects. 13.3.11.4.2. Theor y ANSY S Fluen t provides t wo options f or c omputing the solar load: Fair Weather C onditions metho d and Theor etical M aximum metho d. Although these metho ds ar e similar , ther e is a k ey diff erence. The F air Weather C onditions metho d imp oses gr eater a ttenua tion on the solar load , which is r epres- entative of a tmospher ic conditions tha t are fair–but not c omplet ely clear . The equa tion f or nor mal dir ect irradia tion applying the F air Weather C onditions M etho d is tak en from the ASHR AE Handb ook: (13.15) wher e and are appar ent solar ir radia tion a t air mass and a tmospher ic extinc tion c oefficien t, respectively.These v alues ar e based on the ear th’s sur face on a clear da y. is the solar altitude (in degr ees) ab ove the hor izontal. The equa tion f or dir ect nor mal ir radia tion tha t is used f or the Theor etical M aximum M etho d is tak en from NREL ’s Solar P osition and In tensit y Code (S olpos): (13.16) wher e is the t op of the a tmospher e dir ect nor mal solar ir radianc e and is the c orrection factor used t o acc oun t for reduc tion in solar load thr ough the a tmospher e. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1546Modeling H eat Transf erThe c alcula tion f or the diffuse load in the solar mo del is based on the appr oach suggest ed in the 2001 ASHR AE F undamen tal Handb ook (C hapt er 20, Fenestr ation). The equa tion f or diffuse solar ir ra- diation on a v ertical sur face is giv en b y: (13.17) wher e is a c onstan t whose v alues ar e giv en in Table 7 fr om C hapt er 30 of the 2001 ASHR AE Handb ook of F undamen tals, is the r atio of sk y diffuse r adia tion on a v ertical sur face to tha t on a horizontal sur face (calcula ted as a func tion of inciden t angle), and is the dir ect nor mal ir radia tion at the ear th’s sur face on a clear da y. The equa tion f or diffuse solar ir radia tion f or sur faces other than v ertical sur faces is giv en b y: (13.18) wher e is the tilt angle of the sur face (in degr ees) fr om the hor izontal plane . The equa tion f or gr ound r eflec ted solar ir radia tion on a sur face is giv en b y: (13.19) wher e is the gr ound r eflec tivit y.The t otal diffuse ir radia tion on a giv en sur face will b e the sum of and when the input f or diffuse solar r adia tion is tak en fr om the solar c alcula tor. Other wise , if the constant option is selec ted in the Radia tion dialo g box, then the t otal diffuse ir radia tion will b e the same as sp ecified in the dialo g box. 13.3.11.4.3. Computation of L oad D istribution In calcula ting the solar load tha t will b e inciden t on each sur face, it is nec essar y to distinguish between the c alcula tion of diffuse and dir ect solar loads . A dir ect load will b e tracked fr om par ticip- ating tr ansmissiv e boundar y sur faces and non-par ticipa ting b oundar y sur faces, the f ormer pr ovides some opp ortunit y to attenua te the inc oming flux b y absor ption and r eflec tion, while the non-par ti- cipa ting sur faces allo w the flux t o en ter without an y dr op in in tensit y.The dir ect load is then tr acked through the mo del spac e un til it is inciden t on an opaque sur face, or it e xists thr ough a tr ansmissiv e or non-par ticipa ting b oundar y zone . During its passage , its in tensit y will b e attenua ted as it passes through par ticipa ting semi-tr anspar ent internal w alls, wher e some r adia tion ma y be absorb ed and some ma y be reflec ted.The t otal amoun t of dir ect radia tion tha t is r eflec ted a t internally facing surfaces will b e added t o the sc attered r adia tion budget f or fur ther use la ter. The diffuse load or igina tes a t par ticipa ting tr ansmissiv e boundar y sur faces. It is these sur faces tha t permit diffuse r adia tion t o en ter, irrespective of their or ientation r elative to the dir ection v ector. For each tr ansmissiv e sur face, some of the inc oming diffuse load ma y be immedia tely absorb ed and/or reflec ted t o the outside .The r est is assumed t o be transmitt ed inside and summed fr om all of these surfaces to giv e an initial diffuse budget. Onto this budget is added a fr action of the pr eviously comput ed sc attered r adia tion fr om the dir ect load , the fr action used is defined as an input t o the model. This pr ovides the t otal diffuse load .This is then unif ormly distr ibut ed acr oss all sur faces tha t are par ticipa ting in the solar c alcula tion, irrespective of whether the y are opaque or semi-tr anspar ent. There is no sc ope to define lo cal absor ptivit y for this distr ibution and no biasing with r egar ds pr ox- imit y to transmissiv e sur faces. Note tha t a non-par ticipa ting b oundar y zone will allo w dir ect load t o enter the mo del spac e but will not pr ovide an inc oming quan tity of diffuse load . Note tha t the solar flux tha t is e xternally inciden t on an opaque sur face will b e complet ely disr egar ded , for e xample solar load on an opaque r oof of a mo del whose in ternals only ar e mo deled will not b e 1547Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling R adia tionincluded as a hea t gain. Inst ead, this hea t gain should b e manually c alcula ted and applied as a ther mal c ondition, typic ally using a fix ed hea t flux or a r adia tion/mix ed c ondition. 13.3.11.5. Using the S olar L oad Mo del When y ou w ant to run a st eady-sta te solution with solar load enabled , you simply set up the solar load mo del ( Setting U p the S olar L oad M odel (p.1548 )) and b oundar y conditions ( Setting B oundar y Conditions f or S olar L oading (p.1554 )) for y our c ase, and then r un the simula tion. The solution da ta file will c ontain the solar flux es tha t you c an use f or p ostpr ocessing . For a st eady-sta te solution, the solar loads ar e comput ed on initializa tion. If you w ant to initially solv e a c ase without solar loading (say, for stabilit y) and then add the eff ects of solar loading af terward, you will need t o enable the solar load mo del thr ough the t ext user in terface (TUI). Imp ortant Note tha t you c an c omput e the solar load a t an y time onc e you ha ve set up the mo del b y using the sol-on-demand text interface command (see Additional Text Interface Com- mands (p.1563 ) for details). When y ou w ant to run a tr ansien t solar load simula tion, the pr ocess is the same as f or the st eady- state case but y ou will need t o sp ecify the additional Time S teps p er S olar L oad U pdate par amet er in the Radia tion M odel dialo g box. ANSY S Fluen t will r e-comput e the sun p osition and ir radia tion and up date solar loads with this sp ecified fr equenc y. Imp ortant Note tha t par allel simula tions in volving the solar load mo del ar e set up and c omput ed using the same st eps as in ser ial. 13.3.11.5.1. User -Defined F unc tions (UDFs) for S olar L oad You c an wr ite a user-defined func tion (UDF) t o sp ecify dir ect and diffuse solar in tensit y using the DEFINE_SOLAR_INTENSITY macr o. See DEFINE_SOLAR_INTENSITY for mor e inf ormation. After it is in terpreted or c ompiled , you c an ho ok y our in tensit y UDF f or dir ect or diffuse solar ir radi- ation b y selec ting user-defined in the dr op-do wn lists f or these par amet ers in the Radia tion Model dialo g box. See S tep 2 in Setting U p the S olar L oad M odel (p.1548 ) for details . 13.3.11.5.2. Setting Up the S olar L oad Mo del The solar load mo del is enabled in the Radia tion M odel dialo g box (Figur e 13.39: The R adia tion Model D ialog Box (p.1549 )). Setup → Models → Radia tion Edit... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1548Modeling H eat Transf erFigur e 13.39: The R adia tion M odel D ialo g Box Imp ortant Solar load is a vailable in the 3D solv er only , and c an b e used t o mo del st eady and unst eady flows. The solar load mo del has t wo options: Solar R ay Tracing and Solar Ir radia tion .Solar R ay Tracing can b e applied as a stand-alone solar loading mo del, or it c an b e used in c onjunc tion with one of the ANSY S Fluen t radia tion mo dels .Solar Ir radia tion is a vailable only when the Discr ete Or dina tes (DO) or Monte Carlo (MC) radia tion mo del is enabled . To set up the solar load mo del, perform the f ollowing st eps: 1.Enable the solar load mo del in the Radia tion M odel Dialog Box. a.To enable the solar r ay tracing algor ithm, selec t Solar R ay Tracing under Solar L oad (Fig- ure 13.40: The R adia tion M odel D ialog Box (With S olar L oad M odel S olar R ay Tracing Option) (p.1550 )). 1549Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling R adia tionFigur e 13.40: The R adia tion M odel D ialo g Box (With S olar L oad M odel S olar R ay Tracing Option) b.To enable the S olar Ir radia tion option, first selec t the DO or MC mo del, and then selec t Solar Ir radi- ation under Solar L oad (Figur e 13.41: The R adia tion M odel D ialog Box (with S olar L oad M odel S olar Irradia tion Option) (p.1551 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1550Modeling H eat Transf erFigur e 13.41: The R adia tion M odel D ialo g Box (with S olar L oad M odel S olar Ir radia tion Option) 2.When using the non-gr ay DO or MC mo del, if the w avelengths of the sp ecified bands do not c over the entire solar sp ectrum, a message is wr itten t o the c onsole displa ying wha t percentage of the full solar model has b een c overed. It is r ecommended tha t the full solar sp ectrum is c onsider ed. When using the non-gr ay MC mo del, if y ou only sp ecify one band then F luen t will aut oma tically cover the en tire solar sp ectrum 3.Define the solar par amet ers. a.Enter values f or the X,Y, and Z comp onen ts of the Sun D irection Vector. Alternatively, you c an choose t o ha ve this v ector comput ed fr om the solar c alcula tor b y enabling the Use D irection Comput ed fr om S olar C alcula tor option. 1551Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling R adia tionb.Specify the illumina tion par amet ers. i.Enter a v alue f or Direct Solar Ir radia tion under Illumina tion P aramet ers.This par amet er is the amoun t of ener gy per unit ar ea in due t o dir ect solar ir radia tion. This v alue ma y de- pend on the time of y ear and the clear ness of the sk y. Make your selec tion in the dr op-do wn list next to Direct Solar Ir radia tion and either en ter a constan t value , have the v alue c omput ed from the solar c alcula tor, or sp ecify it using a user-defined func tion . (For mor e inf ormation on wr iting solar in tensit y UDFs , see DEFINE_SOLAR_INTENSITY in the Fluen t Customiza tion Manual .) For tr ansien t simula tions , you ha ve the additional option of sp ecifying a time-dep enden t piec ewise-linear and polynomial profile f or dir ect solar ir radia tion. ii.Enter a v alue f or Diffuse S olar Ir radia tion for the DO mo del only , which is the amoun t of ener gy per unit ar ea in due t o diffuse solar ir radia tion. This v alue ma y dep end on the time of year, the clear ness of the sk y, and also on gr ound r eflec tivit y. Make your selec tion in the dr op- down list ne xt to Diffuse S olar Ir radia tion and either en ter a constan t value , have the v alue comput ed fr om the solar c alcula tor, or sp ecify it using a user-defined func tion . (For mor e in- formation on wr iting solar in tensit y UDFs , see DEFINE_SOLAR_INTENSITY in the .) F or tr an- sien t simula tions , you ha ve the additional option of sp ecifying a time-dep enden t piec ewise- linear and polynomial profile f or diffuse solar ir radia tion. iii.If you ar e using the Solar R ay Tracing solar load mo del ( Figur e 13.40: The R adia tion M odel Dialog Box (With S olar L oad M odel S olar R ay Tracing Option) (p.1550 )), then y ou will need t o en ter a value f or Spectral F raction .The sp ectral fraction is the fr action of inciden t solar r adia tion in the visible par t of the solar r adia tion sp ectrum. (13.20) wher e is the visible inciden t solar r adia tion, and is the t otal inciden t solar r adia tion (visible plus infr ared). 4.Use the solar c alcula tor to comput e solar b eam dir ection and ir radia tion. a.Click Solar C alcula tor... in the Radia tion M odel dialo g box to op en the Solar C alcula tor dialo g box (Figur e 13.42: The S olar C alcula tor D ialog Box (p.1553 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1552Modeling H eat Transf erFigur e 13.42: The S olar C alcula tor D ialo g Box b.In the Solar C alcula tor dialo g box, define the Global P osition by the f ollowing par amet ers: i.Enter a r eal numb er in degr ees f or Longitude .Values ma y range fr om to wher e neg- ative values indic ate the Western hemispher e and p ositiv e values indic ate the E astern hemispher e. ii.Enter a r eal numb er for Latitude in degr ees.Values c an r ange fr om (the S outh P ole) t o (the N orth P ole), with defined as the equa tor. iii.Enter an in teger f or Time zone tha t is the lo cal time z one in hours r elative to Greenwich M ean Time (+-GMT ).This v alue c an r ange fr om to . Imp ortant Note tha t you must sp ecify all thr ee Global P osition par amet ers f or the solar c al- cula tor. c.Define the lo cal Date and Time by the f ollowing par amet ers: i.Enter an in teger f or Day and Month under Day of Year. ii.Enter an in teger f or Hour tha t ranges fr om to under Time of D ay. Enter an in teger or floating p oint numb er for Minut e. The time of da y is based on a 24-hour clo ck: hours and minut es c orresponds t o 12:00 a.m. and hours min c orresponds t o 11:59.99 p .m. For e xample , if the lo cal time was 12:01:30 a.m., you w ould en ter 0 for Hour and 1.5 for Minut e. If the lo cal time w as 4:17 p .m., you w ould en ter 16 for Hour and 17 for Minut e. d.Define the Mesh Or ientation as the v ectors f or N orth and E ast in the CFD mesh sy stem of c oordina tes. 1553Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling R adia tione.Selec t the appr opriate Solar Ir radia tion M etho d.The Fair Weather C onditions is the default metho d. f.Enter an in teger f or Sunshine F raction (default = ). g.Click Apply . The solar c alcula tor output par amet ers ar e comput ed and the r esults ar e reported in the console .The default v alues ar e sho wn b elow: Fair Weather Conditions: Sun Direction Vector: X: -0.0785396, Y: 0.170758, X: 0.982178 Sunshine Fraction: 1 Direct Normal Solar Irradiation (at Earth’s surface) [W/m^2]: 881.635 Diffuse Solar Irradiation - vertical surface: [W/m^2]: 152.107 Diffuse Solar Irradiation - horizontal surface: [W/m^2]: 118.727 Ground Reflected Solar Irradiation - vertical surface: [W/m^2]: 96.4649 5.For tr ansien t simula tions , enter the Time S teps P er S olar L oad U pdate under Update Paramet ers. The numb er of time st eps tha t you sp ecify will dir ect the ANSY S Fluen t solv er to up date the solar load data for the sp ecified flo w-time in tervals in the unst eady solution pr ocess. 13.3.11.5.3. Setting B oundar y Conditions for S olar L oading Onc e you ha ve defined the solar par amet ers f or the solar load mo del ( Setting U p the S olar L oad Model (p.1548 )), you will need t o set up b oundar y conditions f or b oundar y zones tha t will par ticipa te in solar loading .The b oundar y condition dialo g boxes c an b e op ened b y right-click ing the b oundar y name in the tr ee (under Setup/B oundar y Conditions ) and click ing Edit... in the menu tha t op ens; alternatively, you c an op en them fr om the Boundar y Conditions task page: Setup → Boundar y Conditions 13.3.11.5.4. Solar R ay Tracing Note Solar r ay tracing is designed t o be applied t o your geometr ical inf ormation, ther efore, you must include e very side of the e xternal, or out er, enclosur e/boundar y for ray-tracing purposes , unless y ou e xpect tha t solar ir radia tion c annot en ter thr ough such b oundar ies. If you e xclude an y internal z one fr om the solar load c omputa tion, then this w ould mean that the r esulting obstr uction or blo ckage has b een r emo ved which w ould also b e equi- valen t to a tr anspar ent sur face. Excluded w alls will also not par ticipa te in the c omputa tion of sc attered ener gy by the solar load mo del and , ther efore, do not gain an y hea t from scattered ener gy. 1.Set the b oundar y condition f or each inlet and e xit b oundar y zone tha t you w ant to include in solar loading . a.Open the inlet or e xit b oundar y condition dialo g box (for e xample ,Velocity Inlet ) and click the Radia tion tab ( Figur e 13.43: The Velocity Inlet D ialog Box (p.1555 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1554Modeling H eat Transf erFigur e 13.43: The Velocity Inlet D ialo g Box b.Enable the Participa tes in S olar R ay Tracing option (this option is enabled f or all b oundar y condi- tions b y default). If you deac tivate solar r ay tracing b y disabling this option the sur face will b e ignor ed and the solar r ay will pass thr ough it with no in teraction, regar dless of the b oundar y condition t ype. c.Enter a v alue b etween 0 and 1 for the Solar Transmissivit y Factor.This will allo w you t o control the amoun t of solar ir radia tion en tering the domain. By reducing the solar tr ansmissivit y fac tor fr om 1 to 0.5, you c an eff ectively cut the t otal in ternal ener gy sour ce en tering the domain b y half . Imp ortant Note tha t the solar tr ansmissivit y fac tor is applied t o both dir ect and diffuse solar irradia tion c omp onen ts. d.Click OK. 2.Set the b oundar y condition f or each w all b oundar y zone tha t you w ant to include in solar loading . a.Open a Wall boundar y condition dialo g box and click the Radia tion tab . b.Define the w all as opaque or semi-tr anspar ent. (An opaque w all will not allo w an y solar r adia tion to pass thr ough it , while a semi-tr anspar ent sur face will allo w a p ortion of the solar r adia tion t o pass through it.) i.For an opaque w all, selec t opaque from the dr op-do wn list f or BC Type (Figur e 13.44: The Wall Dialog Box (p.1556 )).Then enable the Participa tes in S olar R ay Tracing option (this option is enabled f or all b oundar y conditions b y default) in the Solar B oundar y Conditions group b ox and en ter constan t values f or Direct Visible and Direct IR absor ptivit y. Note tha t if y ou deac tivate solar r ay tracing b y disabling the Participa tes in S olar R ay Tracing option, the sur face will b e 1555Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling R adia tionignor ed and the solar r ay will pass thr ough it with no in teraction, regar dless of the b oundar y condition t ype. Imp ortant Absor ption in the visible and infr ared p ortions of the sp ectrum define the sur- face ma terial for the opaque w all. Figur e 13.44: The Wall D ialo g Box ii.For a semi-tr anspar ent wall, selec t semi-tr anspar ent from the dr op-do wn list f or BC Type (Fig- ure 13.45: The Wall D ialog Box (p.1557 )).Then, enable the Participa tes in S olar R ay Tracing option (this option is enabled f or all b oundar y conditions b y default) in the Solar B oundar y Conditions group b ox and en ter constan t values f or Direct Visible ,Direct IR, and Diffuse H emispher ical absor ptivit y and tr ansmissivit y. Note tha t if y ou deac tivate solar r ay tracing b y disabling the Participa tes in S olar R ay Tracing option, the sur face will b e ignor ed and the solar r ay will pass through it with no in teraction, regar dless of the b oundar y condition t ype. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1556Modeling H eat Transf erFigur e 13.45: The Wall D ialo g Box Imp ortant For semitr anspar ent coupled w alls, the solar r ay tracing settings ar e defined on the or iginal w all and not on the shado w w all. Absor ption and tr ansmittanc e in the visible and infr ared p ortions of the sp ectrum, as w ell as the “shading ” formula tion ( Diffuse H emispher ical), define the sur face ma terial for a semi-tr anspar ent wall.These par amet ers ar e pr operties of the glaz ed unit and should b e provided b y the glazing manufac turer.The dir ect comp onen ts ar e based on nor mal inciden t radia tion (ANSY S Fluen t adjusts this f or the ac tual angle of incidenc e). Most manufac turers presen t this inf ormation in a sligh tly diff erent way so it ma y be nec essar y to seek guidanc e from the supplier . Another useful sour ce of da ta can b e found in the ASHR AE F undamen tals Handb ook, chapt er on F enestr ation. 1557Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling R adia tioniii.Click OK. Imp ortant ANSY S Fluen t will c alcula te the r eflec tivit y as the diff erence between one and the sum of absor ptivit y and tr ansmissivit y: (13.21) 3.Set the b oundar y condition f or each p orous jump b oundar y zone tha t you w ant to include in solar loading .You c an define the b oundar y such tha t it ac ts as a semi-tr anspar ent sur face tha t will allo w a portion of the solar r adia tion t o pass thr ough it , along with fluid flo w. In this w ay you c an r epresen t a partial op ening (f or e xample , a gr ate, a gr ill, or a louv er) tha t is a c ombina tion of gaps and (t ypic ally) opaque sur faces. a.Open the Porous Jump boundar y condition dialo g box (Figur e 13.46: The P orous J ump D ialog Box (p.1558 )). Figur e 13.46: The P orous Jump D ialo g Box b.Define the Face Permeabilit y,Porous M edium Thick ness ,Pressur e-Jump C oefficien t, and Thermal Contact Resistanc e as descr ibed in User Inputs f or the P orous J ump M odel (p.1017 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1558Modeling H eat Transf erc.Define the settings in the Solar B oundar y Conditions group b ox. i.Enable the Participa tes in S olar R ay Tracing option (this option is enabled f or all b oundar y conditions b y default). Note tha t if y ou deac tivate solar r ay tracing b y disabling the Participa tes in S olar R ay Tracing option, the sur face will b e ignor ed and the solar r ay will pass thr ough it with no in teraction, regar dless of the b oundar y condition t ype. ii.Enter constan t values (b etween 0 and 1) f or Direct Visible and Direct IR in the Absor ptivit y group b ox.These v alues ac t as multipliers f or the visible and infr ared p ortions of the dir ect solar radia tion sp ectrum, respectively, to acc oun t for the absor ption of the p orous jump . Imp ortant One r easonable w ay to estima te the Direct Visible and Direct IR absor ptivit y values f or a gr ill, and so on, is to use the pr oduc t of the obstr ucted ar ea fr action and the sur face absor ptivit y. For e xample , if 40% of the gr ill facial ar ea is ob- structed with gr ill sla ts, and the sla ts ha ve a sur face absor ptivit y of 0.7, you could estima te the absor ptivit y as b eing 0.28. iii.Enter constan t values (b etween 0 and 1) f or Direct Visible and Direct IR in the Transmissivit y group b ox.These v alues ac t as multipliers f or the visible and infr ared p ortions of the dir ect solar radia tion sp ectrum, respectively, to acc oun t for the tr ansmissivit y of the p orous jump . Imp ortant One r easonable w ay to estima te the Direct Visible and Direct IR transmissivit y values f or a gr ill, and so on, is to use the op en ar ea fr action. For e xample , if a grill has op enings b etween the sla ts tha t amoun t to 60% of the ar ea, you c ould estima te the tr ansmissivit y as b eing 0.6. d.Click OK. 13.3.11.5.5. Solar Irr adiation 1.For S olar Ir radia tion, all b oundar y conditions ar e set up as nor mal f or the DO or MC mo del, except tha t now you c an selec t semi-tr anspar ent boundar y sur faces tha t will pr ovide a sour ce of solar ir radia tion. a.Open a Wall boundar y condition dialo g box and click the Radia tion tab ( Figur e 13.47: The Wall Dialog Box Radia tion tab with S olar Ir radia tion (p.1560 )). 1559Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling R adia tionFigur e 13.47: The Wall D ialo g Box Radia tion tab with S olar Ir radia tion b.Selec t semi-tr anspar ent from the dr op-do wn list f or BC Type. c.Enable the Use B eam D irection fr om S olar L oad M odel S ettings option, under Solar BC Options , to ha ve the v alues f or b eam dir ection applied fr om the Solar L oad M odel settings in the Radia tion dialo g box. Imp ortant Note tha t the sign of the b eam dir ection tha t is needed f or the DO or MC mo del is opp osite the sun dir ection v ector tha t is en tered or der ived fr om the solar paramet ers.The b eam dir ection in the DO or MC mo del is the dir ection of e xternal radia tion (f or e xample , radia tion c oming fr om the sun), while the sun dir ection vector in the solar load mo del p oints to the sun. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1560Modeling H eat Transf erd.Enable the Use Ir radia tion fr om S olar L oad M odel S ettings option t o ha ve the ir radia tion sp ecified on the R adia tion M odel dialo g box for the S olar L oad mo del applied f or dir ect and diffuse ir radia tion. If selec ted while using the multiband appr oach f or the DO or MC mo dels , the dir ect and diffuse (for DO only) ir radia tion is c alcula ted and applied in each band , acc ording t o the black b ody emission w eigh ting fac tor. When Use Ir radia tion fr om S olar L oad M odel S ettings is enabled , the b eam width will automa tically b e set t o degr ees - the angle subt ended b y the sun. e.Click OK. 13.3.11.5.6. Text Int erface-O nly Commands ANSY S Fluen t has pr ovided some additional c ommands f or solar load setup tha t are only a vailable in the t ext interface.These c ommands ar e pr esen t in the f ollowing sec tions . 13.3.11.5.6.1. Automatic ally Saving S olar R ay Tracing D ata It is p ossible t o dir ect ANSY S Fluen t to aut oma tically sa ve solar load da ta to a gener ic file tha t you can e xamine or use in an e xternal pr ogram. This is done b y executing the t ext command autosave- solar-data from the t ext interface. define → models → radiation → solar-parameters → autosave-solar-data 1.Enter a v alue f or the aut osave solar da ta file fr equenc y when pr ompt ed, in or der t o sp ecify the fr equenc y (in time st eps) a t which y ou w ant the solar load da ta wr itten t o a file .The default v alue is z ero, which means tha t no aut oma tic sa ving is p erformed . 2.Enter the filename , in quota tions . 3.Choose t o wr ite file in binar y format. The t ext interface command f or autosave-solar-data for a file named solar and a fr equenc y of is sho wn b elow: /define/models/radiation/solar-parameters> autosave-solar-data Autosave Solar Data File Frequency [0] 1 Enter Filename [""] "solar" 13.3.11.5.6.2. Automatic ally Reading S olar D ata When y ou ar e executing a tr ansien t simula tion in ser ial or par allel ANSY S Fluen t version 18.2 or la ter and y ou w ant to read the solar load da ta file fr om a ser ial r un p erformed in an ear lier v ersion, you can use the f ollowing t ext command: define → models → radiation → solar-parameters → autoread-solar-data 1.Enter a v alue f or the aut oread solar da ta file fr equenc y when pr ompt ed, in or der t o sp ecify the fr equenc y (in time st eps) a t which y ou w ant the solar load da ta read fr om the file gener ated dur ing the ser ial run. The default v alue is z ero, which means tha t no aut oma tic r eading is p erformed . 2.Enter the filename , in quota tions . 1561Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling R adia tionThe t ext interface command f or autoread-solar-data for a file named solar and a fr equenc y of is sho wn b elow: /define/models/radiation/solar-parameters> autoread-solar-data Autoread Solar Data File Frequency [0] 1 Enter Filename [""] "solar" Use Binary Format for Reading Data Files [yes] 13.3.11.5.6.3. Aligning the C amer a D irection With the P osition of the S un When the solar load mo del is enabled , you c an dir ect ANSY S Fluen t to align the c amer a dir ection with the sun p osition using the t ext interface command: define → models → radiation → solar-parameters → sol-camera-pos This c ommand is useful when y ou ar e executing a tr ansien t simula tion and y ou w ant to captur e an image of y our mo del with solar load par amet ers displa yed (such as solar hea t flux) as the sun p osition changes with time in or der t o cr eate an anima tion. See Postpr ocessing S olar L oad Q uan tities (p.1564 ) for details . 13.3.11.5.6.4. Specifying the Sc attering F raction You c an mo dify the default sc attering fr action ( ) using the t ext interface command: define → models → radiation → solar-parameters → scattering-fraction The sc attering fr action is the amoun t of dir ect radia tion tha t has b een r eflec ted fr om opaque sur faces (after en tering thr ough the tr anspar ent sur faces) tha t will b e consider ed t o remain within the spac e and b e evenly distr ibut ed among all sur faces.The v alue is b etween and . The t ext interface command f or sp ecifying a scattering-fraction of is sho wn b elow: /define/models/radiation/solar-parameters> scattering-fraction Scattering Fraction [1] .5 13.3.11.5.6.5. Appl ying the S olar L oad on A djac ent F luid C ells You c an dir ect ANSY S Fluen t to apply the solar load tha t is c omput ed fr om the solar r ay tracing al- gorithm t o adjac ent fluid c ells b y issuing the f ollowing c ommand a t the t ext interface: define → models → radiation → solar-parameters → sol-adjacent-fluidcells The t ext interface command is sho wn b elow: /define/models/radiation/solar-parameters> sol-adjacent-fluidcells Apply Solar Load on adjacent Fluid Cells? [no] y This c ommand allo ws you t o apply solar loads t o adjac ent fluid c ells only , even if solid or shell c on- duc tion z ones ar e pr esen t. By applying the solar load on adjac ent fluid c ells, you ar e overruling the default or der of the adjac ent cell assignmen t in ANSY S Fluen t which is shell, solid , fluid . 13.3.11.5.6.6. Specifying Q uad Tree R efinement F actor You c an mo dify the default v alue ( ) for the maximum quad tr ee r efinemen t fac tor in the solar r ay tracing algor ithm using the t ext command: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1562Modeling H eat Transf erdefine → models → radiation → solar-parameters → quad-tree-parameters The t ext interface command is sho wn b elow, when a new maximum r efinemen t value of is sp e- cified: /define/models/radiation/solar-parameters> quad-tree-parameters Maximum Quad-Tree Refinement [7] 10 13.3.11.5.6.7. Specifying Gr ound R eflec tivit y You c an mo dify the default v alue ( ) for the gr ound r eflec tivit y using the t ext command: define → models → radiation → solar-parameters → ground-reflectivity Ground r eflec tivit y (Equa tion 13.19 (p.1547 )) includes the c ontribution of r eflec ted solar r adia tion from gr ound sur faces. It is tr eated as par t of the t otal diffuse solar ir radia tion when the solar c alcu- lator is used in c onjunc tion with the Diffuse Solar Irradiation illumina tion par amet er. The default v alue is . /define/models/radiation/solar-parameters> ground-reflectivity Ground Reflectivity [0.2] 0.5 13.3.11.5.6.8. Reverting t o Single B and Implementation of DO Mo del For c onsist ency with c ases set up pr evious t o Fluen t 2019 r1, you c an use the f ollowing c ommand so tha t the c omplet e solar load is applied t o the first band only . define → models → radiation → apply-full-solar-irradiation? /define/models/radiation/apply-full-solar-irradiation? Apply full solar irradiation to first band? [no] yes 13.3.11.5.6.9. Additional Text Int erface Commands Some solar load c ommands tha t are available in the gr aphic al user in terface ar e also made a vailable in the t ext interface. For e xample , you c an tur n the solar load mo del on using the t ext command: define → models → radiation → solar? You c an also en ter the solar c alcula tor par amet ers in the t ext interface by executing the c ommand: define → models → radiation → solar-calculator Onc e invoked, you will b e pr ompt ed t o en ter the solar c alcula tor input par amet ers. To set the illumina tion par amet ers, selec t this option fr om the solar-parameters menu: define → models → radiation → solar-parameters → illumination-parameters And finally , you c an dir ect ANSY S Fluen t to comput e the solar load on demand , by issuing the t ext command: define → models → radiation → solar-parameters → sol-on-demand When the c ommand is initia ted, the solar da ta ar e wr itten t o the c onsole . 1563Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling R adia tion13.3.11.6. Postpr ocessing S olar L oad Q uantities The f ollowing solar load quan tities c an b e used t o visualiz e the illumina ted ar eas and shado ws created by solar r adia tion. •solar hea t flux (tha t is, sum of visible and IR absorb ed solar flux on opaque w alls) •absorb ed visible and IR solar flux (semi-tr anspar ent walls and p orous jump b oundar ies only) •reflec ted visible and IR solar flux (semi-tr anspar ent walls and p orous jump b oundar ies only) •transmitt ed visible and IR solar flux (semi-tr anspar ent walls and p orous jump b oundar ies only) These quan tities ar e available f or p ostpr ocessing of solar loading a t wall b oundar ies and c an b e dis- played as c ontours of Wall F luxes in the Contours dialo g box. For st eady-sta te simula tions , the solar flux da ta is c omput ed a t solution initializa tion and is a vailable f or p ostpr ocessing .You c an also c omput e the solar load a t an y time dur ing y our ANSY S Fluen t session, after y ou ha ve set up the mo del and applied b oundar y conditions .To comput e the solar load on demand , you c an issue the sol-on- demand command in the t ext interface (see Additional Text Interface Commands (p.1563 ) for details). Solar hea t flux, for e xample , can b e displa yed f or sur faces using the Contours dialo g box. A sample dialo g box is sho wn b elow (Figur e 13.48: The C ontours D ialog Box (p.1565 )). Results → Graphics → Contours New... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1564Modeling H eat Transf erFigur e 13.48: The C ontours D ialo g Box 13.3.11.6.1. Solar L oad A nimation at D iffer ent S un P ositions The solar c amer a alignmen t command is useful when y ou w ant to tak e timed pic tures of solar loading eff ects of y our mo del dur ing tr ansien t simula tions , and la ter cr eate anima tions of the image files using an e xternal pr ogram. Follow the pr ocedur e below. 1.Read (or set up) y our tr ansien t case file in ANSY S Fluen t. 2.Set up the aut oma tic e xecution of solution c ommands in the Execut e Commands dialo g box tha t will: 1) displa y solar load par amet er gr aphics , 2) r e-position the solar c amer a such tha t the view is aligned with the instan taneous sun dir ection, and 3) gener ate a pic ture image file ( .tiff ) dur ing the solution process in the Execut e Commands dialo g box. Solution → Calcula tion A ctivities → Execut e Commands Edit... 3.Initializ e and r un the solution. 4.Anima te the .tiff files using an e xternal anima tion t ool. The f ollowing c ommands en tered in the Execut e Commands dialo g box will dir ect ANSY S Fluen t to displa y contours of solar hea t flux, align the c amer a with the cur rent dir ection of the sun, and then 1565Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling R adia tiongener ate a pic ture image file ( .tiff ) of the solar hea t flux c ontour e very 300 time st eps dur ing the unst eady simula tion. See Figur e 13.49: The Ex ecut e Commands D ialog Box (p.1566 ). /di/cont solar-heat-flux ,, /def/mod/rad/solar-para/sol-camera-pos /di/hc "flux-%t.tiff" Figur e 13.49: The E xecut e Commands D ialo g Box 13.3.11.6.2. Reporting and D ispla ying S olar L oad Q uantities ANSY S Fluen t provides some additional solar load v ariables tha t you c an use f or p ostpr ocessing when y our mo del includes solar r ay tracing .You c an gener ate gr aphic al plots or alphanumer ic reports of the f ollowing v ariables: In the Wall F luxes... categor y: •Solar H eat Flux •Transmitt ed Visible S olar F lux (semi-tr anspar ent walls and p orous jump b oundar ies) •Transmitt ed IR S olar F lux (semi-tr anspar ent walls and p orous jump b oundar ies) •Reflec ted Visible S olar F lux (semi-tr anspar ent walls and p orous jump b oundar ies) •Reflec ted IR S olar F lux (semi-tr anspar ent walls and p orous jump b oundar ies) •Absorb ed Visible S olar F lux (semi-tr anspar ent walls and p orous jump b oundar ies) •Absorb ed IR S olar F lux (semi-tr anspar ent walls and p orous jump b oundar ies) See Field F unction D efinitions (p.2959 ) for their definitions . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1566Modeling H eat Transf er13.4. Modeling P eriodic H eat Transf er ANSY S Fluen t is able t o pr edic t hea t transf er in p eriodically r epeating geometr ies, such as c ompac t hea t exchangers , by including only a single p eriodic mo dule f or analy sis. This sec tion discusses str eamwise-p eriodic hea t transf er.The tr eatmen t of str eamwise-p eriodic flo ws is discussed in Periodic F lows (p.1206 ), and a descr iption of no-pr essur e-dr op p eriodic flo w is pr ovided in Periodic B oundar y Conditions (p.999). Information ab out str eamwise-p eriodic hea t transf er is pr esen ted in the f ollowing sec tions: 13.4.1. Overview and Limita tions 13.4.2. Theor y 13.4.3. Using P eriodic H eat Transf er 13.4.4. Solution S trategies f or P eriodic H eat Transf er 13.4.5. Monit oring C onvergenc e 13.4.6. Postpr ocessing f or P eriodic H eat Transf er 13.4.1. Overview and Limita tions The f ollowing sec tions c ontain inf ormation ab out p eriodic hea t transf er: 13.4.1.1. Overview 13.4.1.2. Constr aints for P eriodic H eat Transf er Predic tions 13.4.1.1. Overview As discussed in Overview and Limita tions (p.1206 ), streamwise-p eriodic flo w conditions e xist when the flow pa ttern repeats over some length , with a c onstan t pressur e dr op acr oss each r epeating mo dule along the str eamwise dir ection. Periodic ther mal c onditions ma y be established when the ther mal b oundar y conditions ar e of the constan t wall t emp erature or w all hea t flux t ype. In such pr oblems , the t emp erature field (when sc aled in an appr opriate manner) is p eriodically fully de velop ed [89] (p.4009 ). As for p eriodic flo ws, such problems c an b e analyz ed b y restricting the numer ical mo del t o a single mo dule or p eriodic length. 13.4.1.2. Constr aints for P erio dic H eat Transfer P redic tions In addition t o the c onstr aints for str eamwise-p eriodic flo w discussed in Limita tions f or M odeling Streamwise-P eriodic F low (p.1207 ), the f ollowing c onstr aints must b e met when p eriodic hea t transf er is to be consider ed: •The pr essur e-based solv er must b e used . •The ther mal b oundar y conditions must b e of the sp ecified hea t flux or c onstan t wall temp erature type. Further mor e, in a giv en pr oblem, these ther mal b oundar y types c annot b e combined: all b oundar ies must be either c onstan t temp erature or sp ecified hea t flux. You c an, however, include c onstan t-temp erature walls and z ero-hea t-flux w alls in the same pr oblem. For the c onstan t-temp erature case, all w alls must b e at the same t emp erature (pr ofiles ar e not allo wed) or z ero hea t flux. For the hea t flux c ase, profiles and/or different values of hea t flux ma y be sp ecified a t diff erent walls. •When c onstan t-temp erature wall b oundar ies ar e used , you c annot include visc ous hea ting eff ects or an y volumetr ic hea t sour ces. 1567Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling P eriodic H eat Transf er•In cases tha t involve solid r egions , the r egions c annot str addle the p eriodic plane . •The ther modynamic and tr ansp ort properties of the fluid (hea t capacit y, ther mal c onduc tivit y, visc osity, and densit y) cannot b e func tions of t emp erature. (You c annot , ther efore, mo del r eacting flo ws.) Transp ort properties ma y, however, vary spa tially in a p eriodic manner , and this allo ws you t o mo del p eriodic turbulen t flows in which the eff ective turbulen t transp ort properties (eff ective conduc tivit y, effective visc osity) vary with the (p eriodic) turbulenc e field . Theor y (p.1568 ) and Using P eriodic H eat Transf er (p.1569 ) provide mor e detailed descr iptions of the input r equir emen ts for p eriodic hea t transf er. 13.4.2. Theor y Streamwise-p eriodic flo w with hea t transf er fr om c onstan t-temp erature walls is one of t wo classes of periodic hea t transf er tha t can b e mo deled b y ANSY S Fluen t. A p eriodic fully de velop ed t emp erature field c an also b e obtained when hea t flux c onditions ar e sp ecified . In such c ases , the t emp erature change b etween p eriodic b oundar ies b ecomes c onstan t and c an b e related t o the net hea t addition from the b oundar ies as descr ibed in this sec tion. Imp ortant Periodic hea t transf er can b e mo deled only if y ou ar e using the pr essur e-based solv er. 13.4.2.1. Definition of the P erio dic Temp eratur e for C onstant- Temp eratur e Wall Conditions For the c ase of c onstan t wall t emp erature, as the fluid flo ws thr ough the p eriodic domain, its t emp er- ature appr oaches tha t of the w all b oundar ies. However, the t emp erature can b e sc aled in such a w ay that it b ehaves in a p eriodic manner . A suitable sc aling of the t emp erature for p eriodic flo ws with constan t-temp erature walls is [89] (p.4009 ) (13.22) The bulk t emp erature, , is defined b y (13.23) wher e the in tegral is tak en o ver the inlet p eriodic b oundar y ( ). It is the sc aled t emp erature, , which obeys a p eriodic c ondition acr oss the domain of length . 13.4.2.2. Definition of the P erio dic Temp eratur e Change σ for Sp ecified H eat F lux Conditions When p eriodic hea t transf er with hea t flux c onditions is c onsider ed, the f orm of the unsc aled t emp er- ature field b ecomes analo gous t o tha t of the pr essur e field in a p eriodic flo w: (13.24) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1568Modeling H eat Transf erwher e is the p eriodic length v ector of the domain. This t emp erature gr adien t, , can b e wr itten in terms of the t otal hea t addition within the domain, , as (13.25) wher e is the sp ecified or c alcula ted mass flo w rate. 13.4.3. Using P eriodic H eat Transf er A typic al calcula tion in volving b oth str eamwise-p eriodic flo w and p eriodic hea t transf er is p erformed in two par ts. First, the p eriodic v elocity field is c alcula ted (t o convergenc e) without c onsider ation of the t emp erature field . Next, the v elocity field is fr ozen and the r esulting t emp erature field is c alcula ted. These p eriodic flo w calcula tions ar e acc omplished using the f ollowing pr ocedur e: 1.Set up a mesh with tr ansla tionally p eriodic b oundar y conditions . 2.Specify c onstan t ther modynamic and molecular tr ansp ort properties. 3.Specify either the p eriodic pr essur e gr adien t or the net mass flo w rate thr ough the p eriodic b oundar ies. 4.Comput e the p eriodic flo w field , solving momen tum, continuit y, and (optionally) turbulenc e equa tions . 5.Specify the ther mal b oundar y conditions a t walls as either hea t flux or c onstan t temp erature. 6.Define an inlet bulk t emp erature. 7.Solve the ener gy equa tion (only) t o pr edic t the p eriodic t emp erature field . In or der t o mo del the p eriodic hea t transf er, you will need t o set up y our p eriodic mo del in the manner descr ibed in User Inputs f or the P ressur e-Based S olver (p.1208 ) for p eriodic flo w mo dels with the pr essur e- based solv er, noting the r estrictions discussed in Limita tions f or M odeling S treamwise-P eriodic Flow (p.1207 ) and Constr aints for P eriodic H eat Transf er P redic tions (p.1567 ). In addition, you will need to pr ovide the f ollowing inputs r elated t o the hea t transf er mo del: 1.Enable the solution of the ener gy equa tion b y right-click ing Energy in the tr ee (under Setup/M odels ) and click ing On in the menu tha t op ens ( Figur e 13.1: Enabling the Ener gy Equa tion (p.1468 )). Setup → Models → Energy On 2.Define the ther mal b oundar y conditions acc ording t o one of the f ollowing pr ocedur es.The b oundar y condition dialo g boxes c an b e op ened b y right-click ing the b oundar y name in the tr ee (under Setup/B oundar y Conditions ) and click ing Edit... in the menu tha t op ens; alternatively, you c an op en them fr om the Boundar y Conditions task page: Setup → Boundar y Conditions •If you ar e mo deling p eriodic hea t transf er with sp ecified-t emp erature boundar y conditions , set the w all temp erature for all w all b oundar ies in their r espective Wall dialo g box. Note tha t all w all b ound- aries must b e assigned the same t emp erature and tha t the en tire domain (e xcept the p eriodic b ound- aries) must b e “enclosed ” by this fix ed-t emp erature condition, or b y symmetr y or adiaba tic ( =0) boundar ies. 1569Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling P eriodic H eat Transf er•If you ar e mo deling p eriodic hea t transf er with sp ecified-hea t-flux b oundar y conditions , set the w all heat flux in the Wall dialo g box for each w all b oundar y.You c an define diff erent values of hea t flux on different wall b oundar ies, but y ou should ha ve no other t ypes of ther mal b oundar y conditions ac tive in the domain. 3.Define solid r egions , if appr opriate, acc ording t o one of the f ollowing pr ocedur es.The c ell z ones c an b e defined b y right-click ing the z one name in the tr ee (under Setup/C ell Z one C onditions ), or using the Cell Z one C onditions task page: Setup → Cell Z one C onditions •If you ar e mo deling p eriodic hea t transf er with sp ecified-t emp erature conditions , conduc ting solid r egions can b e used within the domain, provided tha t on the p erimet er of the domain the y are enclosed b y the fix ed-t emp erature condition. Heat gener ation within the solid r egions is not allo wed when y ou ar e solving p eriodic hea t transf er with fix ed-t emp erature conditions . •If you ar e mo deling p eriodic hea t transf er with sp ecified-hea t-flux c onditions , you c an define c onduc ting solid r egions a t an y location within the domain, including v olumetr ic hea t addition within the solid , if desir ed. 4.Set constan t ma terial pr operties (densit y, hea t capacit y, visc osity, ther mal c onduc tivit y),not temp erature- dep enden t properties, using the Create/Edit M aterials dialo g box.This dialo g box can b e op ened b y right-click ing the ma terial name in the tr ee (under Setup/M aterials) and click ing Edit... in the menu tha t opens; alternatively, you c an op en them fr om the Materials task page: Setup → Materials 5.Specify the Upstr eam Bulk Temp erature in the Periodic C onditions dialo g box, which c an b e op ened from Boundar y Conditions task page: Setup → Boundar y Conditions → Periodic C onditions ... Imp ortant If you ar e mo deling p eriodic hea t transf er with sp ecified-t emp erature conditions , the bulk t emp erature should not b e equal t o the w all t emp erature, sinc e this will giv e you the tr ivial solution of c onstan t temp erature everywher e. 6.Set the solution par amet ers as descr ibed in Solution S trategies f or P eriodic H eat Transf er (p.1570 ). 7.Run the solution and monit or the c onvergenc e as descr ibed in Monit oring C onvergenc e (p.1571 ). 8.Postpr ocess the r esults as descr ibed in Postpr ocessing f or P eriodic H eat Transf er (p.1571 ). 13.4.4. Solution S trategies f or P eriodic H eat Transf er After completing the inputs descr ibed in Using P eriodic H eat Transf er (p.1569 ), you c an solv e the flo w and hea t transf er pr oblem t o convergenc e.The most efficien t appr oach t o the solution, however, is a sequen tial one in which the p eriodic flo w is first solv ed without hea t transf er and then the hea t transf er is solv ed lea ving the flo w field unalt ered.This sequen tial appr oach is acc omplished as f ollows: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1570Modeling H eat Transf er1.Disable solution of the ener gy equa tion in the Equa tions dialo g box; this dialo g box is acc essed b y right- click ing Solution C ontrols in the tr ee (under Solution ) and click ing Equa tions ... in the menu tha t op ens. Solution → Controls Equa tions ... 2.Solve the r emaining equa tions (c ontinuit y, momen tum, and , optionally , turbulenc e par amet ers) t o con- vergenc e to obtain the p eriodic flo w field . Imp ortant When y ou initializ e the flo w field b efore beginning the c alcula tion, use the mean v alue between the inlet bulk t emp erature and the w all t emp erature for the initializa tion of the t emp erature field . 3.Retur n to the Equa tions dialo g box and tur n off solution of the flo w equa tions and tur n on the ener gy solution. 4.Solve the ener gy equa tion t o convergenc e to obtain the p eriodic t emp erature field of in terest. While y ou c an solv e your p eriodic flo w and hea t transf er pr oblems b y consider ing b oth the flo w and heat transf er simultaneously , you will find tha t the pr ocedur e outlined ab ove is mor e efficien t. 13.4.5. Monit oring C onvergenc e If you ar e mo deling p eriodic hea t transf er with sp ecified-t emp erature conditions , you c an monit or the value of the bulk t emp erature ratio (13.26) during the c alcula tion b y creating a r eport plot tha t includes bulk t emp erature ratio ( periodic-bulk- temp erature-ratio), to ensur e tha t you r each a c onverged solution. See Monit oring S tatistics (p.2655 ) for additional inf ormation. 13.4.6. Postpr ocessing f or P eriodic H eat Transf er The ac tual t emp erature field pr edic ted b y ANSY S Fluen t in p eriodic mo dels will not b e periodic, and viewing the t emp erature results dur ing p ostpr ocessing will displa y this ac tual t emp erature field ( of Equa tion 13.22 (p.1568 )).The displa yed t emp erature ma y exhibit v alues outside the r ange defined by the inlet bulk t emp erature and the w all t emp erature.This is p ermissible sinc e the ac tual t emp erature profile a t the inlet p eriodic fac e will ha ve temp eratures tha t are higher or lo wer than the inlet bulk temp erature. Static Temp erature is found in the Temp erature... categor y of the v ariable selec tion dr op-do wn list tha t app ears in p ostpr ocessing dialo g boxes. Figur e 13.50: Temp erature Field in a 2D H eat Exchanger G eometr y With F ixed Temp erature Boundar y Conditions (p.1572 ) sho ws the t emp erature field in a p eriodic hea t exchanger geometr y. 1571Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling P eriodic H eat Transf erFigur e 13.50: Temp erature Field in a 2D H eat Exchanger G eometr y With F ixed Temp erature Boundar y Conditions Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1572Modeling H eat Transf erChapt er 14: Modeling H eat Exchangers Many engineer ing sy stems , including p ower plan ts, clima te control, and engine c ooling sy stems t ypic ally contain tubular hea t exchangers . However, for most engineer ing pr oblems , it is impr actical to mo del individual fins and tub es of a hea t exchanger c ore. In pr inciple , hea t exchanger c ores in troduce a pressur e dr op t o the pr imar y fluid str eam and tr ansf er hea t from or t o a sec ond fluid (f or e xample , a coolan t), referred t o her e as the auxiliar y fluid . ANSY S Fluen t provides t wo distinc t metho ds of mo deling a hea t exchanger : the dual c ell mo del and the macr o mo del. These mo dels c an b e used t o comput e the auxiliar y fluid inlet t emp erature for a fix ed heat rejec tion or the t otal hea t rejec tion f or a fix ed auxiliar y fluid inlet t emp erature.The dual c ell model allo ws the solution of the passes of the auxiliar y flo w on a separ ate mesh, tha t is, other than the primar y fluid mesh (see Figur e 14.1: An Example of a F our-P ass H eat Exchanger (p.1573 )), unlik e the macr o model, wher e the auxiliar y flo w passes ar e mo deled as 1D flo w. Figur e 14.1: An Example of a F our-P ass H eat Exchanger Imp ortant Note tha t the hea t exchanger mo dels ar e not appr opriate for mo deling a c old-only flo w; in such a c ase, you should inst ead use the p orous media mo del, as descr ibed in Porous M edia Conditions (p.864). For theor etical inf ormation ab out the v arious hea t exchanger mo dels , refer to Heat Exchangers in the Theor y Guide . The f ollowing sec tions c ontain inf ormation ab out the hea t exchanger mo dels: 1573Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.14.1. Choosing a H eat Exchanger M odel 14.2. The D ual C ell M odel 14.3. The M acro Heat Exchanger M odels 14.4. Postpr ocessing f or the H eat Exchanger M odel 14.5. Useful R eporting TUI C ommands 14.1. Choosing a H eat Exchanger M odel ANSY S Fluen t provides v arious options f or mo deling hea t exchangers , each with their o wn f eatures and limita tions .The f ollowing instr uctions c an help y ou det ermine which option/c ombina tion of options is the most appr opriate for y our pr oblem. 1.Decide whether y ou w ant to use the dual c ell mo del or the macr o mo del. a.The dual c ell mo del pr ovides the gr eatest fle xibilit y with r egar d to the shap e of the hea t exchanger core and the na ture of the mesh, and allo ws the auxiliar y fluid t o be highly non-unif orm as it en ters the c ore (for e xample , due t o passing thr ough arbitr ary shap ed inlet tanks). However, the dual c ell model ma y need t o be disc oun ted as an option b ecause of the f ollowing limita tions: •If the hea t exchanger p erformanc e da ta tha t you ha ve is in the f orm of a v elocity vs. effectiveness curve, the dual c ell mo del c annot b e used . •The dual c ell mo del do es not allo w you t o mo del phase change in the auxiliar y fluid . If the pr evious limita tions ar e not r elevant for y our pr oblem, you c an pr oceed dir ectly t o using the dual c ell mo del, as descr ibed in Using the D ual C ell H eat Exchanger M odel (p.1576 ). b.While the macr o mo del has mor e restrictions than the dual c ell mo del, it is quit e suitable f or a thin 3D heat exchanger c ore with a r ectangular cr oss-sec tion, wher e the pass-t o-pass plane is p erpendicular to the pr imar y flo w dir ection, the auxiliar y flo w is unif orm (so it c an b e treated as a 1D flo w), and the mesh is unif orm and str uctured.To verify tha t your pr oblem c an t oler ate the limita tions of the macr o model, see Restrictions (p.1586 ). 2.If you chose t o use the macr o mo del in the pr evious st ep, you must decide whether y ou w ant to use the group ed or ungr oup ed v ersion of this mo del. If you w ant to define a single hea t exchanger using multiple fluid z ones , or if y ou w ould lik e to connec t the fluid flo w pa th among multiple hea t exchangers , you should use the gr oup ed v ersion, as descr ibed in Using the G roup ed M acro Heat Exchanger M odel (p.1598 ). Other wise , you c an use the ungr oup ed v ersion, as descr ibed in Using the U ngroup ed M acro Heat Exchanger M od- el (p.1586 ). 3.If you chose t o use the macr o mo del in the st ep 1., you must decide whether y ou w ant to mo del the hea t transf er using the numb er-of-tr ansf er-units (NTU) metho d or the simple eff ectiveness metho d.This decision largely r ests on the k ind of e xperimen tal da ta tha t you ha ve: the NTU metho d requir es tha t you pr ovide the v arious pr imar y fluid flo w rates and auxiliar y fluid flo w rates and the c orresponding hea t transf er values; the simple eff ectiveness metho d requir es tha t you pr ovide the da ta p oints for a cur ve tha t defines ho w the eff ectiveness (tha t is, the r atio of ac tual r ate of hea t transf er b etween the pr imar y and auxiliar y fluids to the maximum p ossible r ate of hea t transf er) v aries with the fluid v elocity. Additionally , you should Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1574Modeling H eat Exchangersconsider the diff erences b etween the t wo hea t transf er mo dels outlined in Table 14.1: NTU M odel Vs. Simple Effectiveness M odel (p.1575 ). Table 14.1: NTU M odel Vs. Simple E ffectiveness M odel Simple E ffectiveness ModelNTU M odel single phase and t wo phasesingle phase only How man y phases ar e allo wed in the auxiliar y flo w? No Yes Can y ou mo del pr imar y fluid-side r everse flo w? No Yes Can the pr imar y fluid ha ve a v ariable densit y? Yes No Must the pr imar y fluid hea t capacit y be less than the auxiliar y fluid hea t capacit y? You will sp ecify whether y ou w ant the NTU or simple eff ectiveness mo del in the Model D ata tab of either the Ungr oup ed M acro H eat Exchanger dialo g box or the Heat Exchanger G roup dialo g box, dep ending on whether y ou opt ed f or the ungr oup ed or gr oup ed v ersion of the macr o mo del, respectively. An overview of the options a vailable t o you when mo deling hea t exchangers is sho wn in Figur e 14.2: Heat Exchanger M odeling Options (p.1575 ). Figur e 14.2: Heat Exchanger M odeling Options 14.2. The D ual C ell M odel The dual c ell hea t exchanger mo del allo ws the solution of b oth the pr imar y and auxiliar y flo w on sep- arate co-lo cated meshes and c ouples the t wo flo ws only thr ough hea t transf er a t the hea t exchanger core. For theor etical inf ormation ab out this mo del, refer to The D ual C ell M odel in the Theor y Guide . 1575Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.The D ual C ell M odel14.2.1. Restr ictions The f ollowing r estrictions e xist f or the dual c ell hea t exchanger mo dels: •The simple eff ectiveness mo del is not a vailable . •The hea t exchanger p erformanc e da ta must b e in the f orm of hea t transf er rates or numb er of tr ansf er units (NTU) f or auxiliar y / pr imar y fluid flo w rate combina tions , rather than a v elocity vs. effectiveness cur ve. •In the c ase of a hea t exchanger in which the pr imar y and auxiliar y meshes ar e not iden tical, hea t transf er may be non-c onser vative (tha t is, the hea t lost b y the hot fluid ma y not equal the hea t gained b y the c old fluid). To minimiz e the diff erence in hea t transf er, the t opology and siz e of the pr imar y and auxiliar y cells should b e as similar as p ossible , with the ideal b eing one-t o-one c ell c onduc tivit y. Note tha t you c an mak e the meshes iden tical by copying a z one via the mesh/modify-zones/copy-move-cell-zone text command . 14.2.2. Using the D ual C ell H eat Exchanger M odel The st eps f or setting up the dual c ell hea t exchanger mo del is as f ollows: 1.Read the mesh file . a.If the mesh file do es not alr eady contain o verlapping hea t exchanger c ores for pr imar y and auxiliar y fluids , then y ou must cr eate a duplic ate of the z one tha t represen ts the c ore using the f ollowing t ext command: mesh → modify-zones → copy-move-cell-zone See Copying C ell Z ones (p.818) for details on c opying meshes . b.Make sur e tha t the auxiliar y fluid mesh is divided in to separ ate zones , one f or each pass . Domain → Zones → Separ ate → Cells ... See Separ ating C ell Z ones (p.807) for details on separ ating meshes . c.Make sur e tha t the inlet and outlet f or the hea t exchanger ar e two separ ate zones . 2.Enable the c alcula tion of ener gy in the Energy dialo g box. Setup → Models → Energy ON 3.Enable the Dual C ell M odel in the Heat Exchanger M odel dialo g box and click Define ... (Figur e 14.3: The Heat Exchanger M odel D ialog Box (p.1577 )). Setup → Models → Heat Exchanger Edit... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1576Modeling H eat ExchangersFigur e 14.3: The H eat Exchanger M odel D ialo g Box 4.Specify the inputs t o the dual c ell hea t exchanger mo del, using the Dual C ell H eat Exchanger dialo g box (Figur e 14.4: The D ual C ell H eat Exchanger D ialog Box (p.1577 )). Figur e 14.4: The D ual C ell H eat Exchanger D ialo g Box 5.Click New... to define the hea t exchanger .The Set D ual C ell H eat Exchanger dialo g box will app ear (Figur e 14.5: The S et D ual C ell H eat Exchanger D ialog Box (p.1578 )), wher e you will define the hea t exchanger paramet ers. 1577Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.The D ual C ell M odelFigur e 14.5: The S et D ual C ell H eat Exchanger D ialo g Box a.Enter the hea t exchanger Name or k eep the default name .The suffix -1 is incr emen ted aut oma tically on defining mor e than one hea t exchanger . b.In the Fluid Z ones tab ( Figur e 14.5: The S et D ual C ell H eat Exchanger D ialog Box (p.1578 )) i.Specify the Numb er of P asses of y our hea t exchanger . ii.Selec t the appr opriate Primar y and Auxiliar y Fluid Z one , represen ting the hea t exchanger c ore. Imp ortant The selec ted z ones must b e overlapping in ph ysical spac e. c.Click the Heat Rejec tion tab ( Figur e 14.6: The H eat Rejec tion Tab (p.1579 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1578Modeling H eat ExchangersFigur e 14.6: The H eat Rejec tion Tab i.If you selec t Fixed H eat Rejec tion , set the inputs f or the f ollowing: •Heat Rejec tion Targeted which is the hea t rejec tion desir ed fr om the hea t exchanger . •Inlet Z one f or Temp erature Updates allo ws ANSY S Fluen t to change the t emp erature of the specified inlet z one in or der t o ma tch the tar geted hea t rejec tion. •Temp erature Update Under-Relaxa tion is a fac tor tha t controls c onvergenc e. •Iteration In terval B etween Temp erature Updates is used t o control div ergenc e. ii.Selec t Fixed Inlet Temp erature if the output desir ed is t otal hea t rejec tion. d.Click the Performanc e Data tab ( Figur e 14.7: The P erformanc e Data Tab (p.1580 )). 1579Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.The D ual C ell M odelFigur e 14.7: The P erformanc e D ata Tab You must decide whether y ou will selec t Raw D ata or NTU D ata from the Options list. Using the Raw D ata option sp ecifies tha t the eff ectiveness ( ) is e valua ted as the r atio of the r ate of heat transf er b etween the pr imar y and auxiliar y fluids (which y ou define in a table f ormat) to the maximum p ossible r ate of hea t transf er ( ) for the cur rent flo w regime (see Equa tion 6.7 in the Theor y Guide ).The c alcula ted efficienc y is then used t o calcula te the NTU v alue using the cr ossflo w formula f or each and e very set of pr imar y and auxiliar y flo w rates. If the hea t exchanger manufac turer used a similar appr oach in e valua ting the NTU v alues , then ther e is no diff erence between the Raw D ata and NTU D ata options . However, if a diff erent metho dolo gy was used b y the manufac turer tha t acc oun ts for some p ossible non-unif ormity of the pr ofile or f or the par tial mixing of the flo w str eam, then the NTU D ata option is lik ely to be mor e accur ate. Similar ly, you ma y be able t o assess mor e accur ate NTU v alues f or y our case using tables fr om the r elevant literature.This c an e ven include some mixing of the onc oming flow str eam, for situa tions wher e the pr imar y flo w can de viate from the dir ection nor mal t o the heat exchanger tub es; this c an happ en in hea t exchangers wher e the fins ar e either v ery spac ed or absen t.Therefore, the NTU D ata option c an b e mor e accur ate if the NTU v alues ar e ga ther ed at non-ideal c onditions tha t bear a close r esemblanc e to your simula ted sc enar io. i.If you selec t the Raw D ata option, then sp ecify the f ollowing: •Heat Transf er D ata... opens the Heat Transf er D ata Table D ialog Box (p.3282 ), wher e you will enter experimen tal da ta tha t defines ho w hea t transf er values r elate to the fluid flo w rates (Fig- ure 14.8: The H eat Transf er D ata Table D ialog Box (p.1581 )). See Specifying H eat Exchanger P er- formanc e Data (p.1592 ) mor e details . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1580Modeling H eat ExchangersFigur e 14.8: The H eat Transf er D ata Table D ialo g Box •Effectiveness-NTU Rela tion comput es the NTU v alues fr om the hea t transf er da ta. Choose cross-flo w-unmix ed,parallel-flo w, or coun ter-flo w, all of which ar e descr ibed in NTU R elations . •Auxiliar y Fluid Temp erature is the inlet r eference temp erature for the auxiliar y fluid . •Primar y Fluid Temp erature is the inlet r eference temp erature for the pr imar y fluid . ii.If you selec t the NTU D ata option, click NTU Table ... to acc ess the NTU Table dialo g box. Popula te this table in the same manner as descr ibed pr eviously f or the Heat Transf er D ata Table D ialog Box (p.3282 ). More inf ormation is a vailable in Specifying H eat Exchanger P erformanc e Data (p.1592 ). e.Click the Frontal A rea tab .You ha ve the option t o sp ecify the Primar y and Auxiliar y Fluid C ore Frontal A rea directly, or c omput e the ar ea fr om a sur face zone , as sho wn in Figur e 14.9: The F rontal Area Tab (p.1582 ). 1581Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.The D ual C ell M odelFigur e 14.9: The F rontal A rea Tab f.Click the Coupling tab if y ou w ant to couple the hea t exchanger passes ( Figur e 14.10: The C oupling Tab (p.1583 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1582Modeling H eat ExchangersFigur e 14.10: The C oupling Tab Consider the f ollowing e xample illustr ating the c oupling of a f our-pass hea t exchanger . Figur e 14.11: An Example of a F our-P ass H eat Exchanger 1583Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.The D ual C ell M odelFigur e 14.11: An Example of a F our-P ass H eat Exchanger (p.1583 ) sho ws a f our-pass hea t exchanger with air as the pr imar y fluid and the c oolan t as the auxiliar y fluid .The c oolan t flo ws thr ough the tub es in a ser pentine manner and air flo ws nor mal t o the tub es, forming a cr oss flo w pa ttern. To mo del this t ype of flo w using the dual c ell hea t exchanger mo del, you must first gener ate the mesh. The mesh should c ontain the f ollowing: i.A single pr imar y cell z one . ii.Four adjac ent auxiliar y cell z ones , one f or each pass . Each auxiliar y zone should b e separ ated fr om the other b y a c oupled or unc oupled w all. Each pass will ha ve its o wn inlet and outlet z ones . iii.The pr imar y and f our auxiliar y zones should o verlap in ph ysical spac e. In the Coupling tab ,mass-w eigh ted-a verage is selec ted b y default f or the Temp erature of the outlet of P ass 1 t o the inlet of P ass 2. Similar ly, the mass-w eigh ted-a verage t emp erature of the outlet of P ass 2 will b e applied a t the inlet z one of P ass 3, and so on. Alternatively, you c an couple the passes b y using Profiles ... in the Boundar y Conditions task page or b y using user- defined func tions t o define the Temp erature in the Thermal tab of the r elevant boundar y condition dialo g boxes. If you do so , mak e sur e you selec t none from the Temp erature drop- down list in the Coupling tab of the Set D ual H eat Exchanger dialo g box. Imp ortant Make sur e to sp ecify the auxiliar y zones in the c orrect order (tha t is the z one f or P ass 1 should b e selec ted first , then P ass 2, and so on) in the Fluid Z ones tab of the Set Dual C ell H eat Exchanger dialo g box. g.Click Apply to sa ve the hea t exchanger inputs . 6.To view the plot of NTU v s. primar y mass flo w rate for each auxiliar y mass flo w rate, click Plot NTU . The Plot NTU butt on will plot the p erformanc e da ta cur ve for the selec ted hea t exchanger .The performanc e da ta is supplied thr ough the Performanc e D ata tab . When y ou close the Set D ual C ell H eat Exchanger dialo g box, you will r etur n to the Dual C ell Heat Exchanger dialo g box, wher e you should no w see the hea t exchanger name in the Heat Exchanger list. You c an •Modify the settings of hea t exchanger b y selec ting it fr om the list and click ing Modify .... •Copy the da ta of one hea t exchanger t o another using the Copy butt on, assuming y ou ha ve mor e than one hea t exchanger . •Delete an y unw anted hea t exchangers b y selec ting the hea t exchanger fr om the list and click ing Delet e. Imp ortant All the inputs ar e copied e xcept f or the name , primar y fluid z one and auxiliar y fluid zone . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1584Modeling H eat Exchangers14.3. The M acro Heat Exchanger M odels To use the macr o hea t exchanger mo del, you must define one or mor e fluid z one(s) t o represen t the heat exchanger c ore.Typic ally, the fluid z one is siz ed t o the dimension of the c ore itself . As par t of the setup pr ocedur e, you will define the auxiliar y fluid pa th, the numb er of macr os, and the ph ysical pr op- erties and op erating c onditions of the c ore (pr essur e dr op par amet ers, hea t exchanger eff ectiveness , auxiliar y fluid flo w rate, and so on). Additional inf ormation ab out macr o hea t exchangers c an b e found in Overview of the M acro Heat Ex- changer M odels in the Theor y Guide . For the theor y behind these mo dels , refer to Macro Heat Exchanger Model Theor y in the Theor y Guide . ANSY S Fluen t provides t wo hea t transf er mo dels: the default NTU mo del and the simple eff ectiveness model. The simple eff ectiveness mo del in terpolates the eff ectiveness fr om the v elocity vs. effectiveness curve tha t you pr ovide . For the NTU mo del, ANSY S Fluen t calcula tes the eff ectiveness , , from the NTU value tha t is c alcula ted b y ANSY S Fluen t from the hea t transf er da ta pr ovided b y you in tabular f ormat. ANSY S Fluen t will aut oma tically c onvert this hea t transf er da ta to a pr imar y fluid mass flo w rate vs. NTU curve (this cur ve will b e piec ewise linear). This cur ve will b e used b y ANSY S Fluen t to calcula te the NTU for macr os based on their siz e and pr imar y fluid flo w rate. The NTU mo del pr ovides the f ollowing f eatures: •The mo del c an b e used t o check hea t capacit y for b oth the pr imar y and the auxiliar y fluid and tak es the lesser of the t wo for the c alcula tion of hea t transf er. •The mo del c an b e used t o mo del hea t transf er to the pr imar y fluid fr om the auxiliar y fluid , and vic e versa. •The mo del c an b e used t o mo del pr imar y fluid-side r everse flo w. •The mo del c an b e used with v ariable densit y of the pr imar y fluid . •The mo del c an b e used in either the ser ial or par allel ANSY S Fluen t solv ers. •The mo del c an b e used t o mak e a net work of hea t exchangers using a hea t exchanger gr oup ( Using the Group ed M acro Heat Exchanger M odel (p.1598 )). •Transien t profiles c an b e used f or the auxiliar y fluid inlet t emp erature and f or total hea t rejec tion. •Transien t profiles c an b e used f or auxiliar y mass flo w rates. The simple eff ectiveness mo del pr ovides the f ollowing f eatures: •The mo del c an b e used t o mo del hea t transf er fr om the auxiliar y fluid t o the pr imar y fluid , and vic e versa. •The auxiliar y fluid pr operties c an b e a func tion of pr essur e and t emp erature, ther efore allo wing phase change of the auxiliar y fluid . •The mo del c an b e used b y ser ial as w ell as par allel solv ers. •The mo del c an b e used t o mak e a net work of hea t exchangers using a hea t exchanger gr oup ( Using the Group ed M acro Heat Exchanger M odel (p.1598 )). •Transien t profiles c an b e used f or the auxiliar y fluid inlet t emp erature and f or total hea t rejec tion. •Transien t profiles c an b e used f or auxiliar y mass flo w rates. 1585Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.The M acro Heat Exchanger M odelsFor additional inf ormation, see the f ollowing sec tions: 14.3.1. Restrictions 14.3.2. Using the U ngroup ed M acro Heat Exchanger M odel 14.3.3. Using the G roup ed M acro Heat Exchanger M odel 14.3.1. Restr ictions The f ollowing r estrictions e xist f or the macr o hea t exchanger mo dels: •The c ore must b e a 3D mesh with a cr oss-sec tion tha t is appr oxima tely r ectangular in shap e. •The pr imar y fluid str eamwise dir ection (see Equa tion 6.1 in the Theor y Guide ) must b e aligned with one of the thr ee or thogonal ax es defined b y the r ectangular c ore. •The pass-t o-pass plane must b e perpendicular t o the pr imar y fluid str eamwise dir ection. •The t wo dimensions of the pass-t o-pass plane c an each b e discr etized in to multiple macr oscopic c ells (macr os), but in the dir ection p erpendicular t o this plane the macr os c annot b e sub divided . •It is highly r ecommended tha t the fr ee-f orm Tet mesh is not used in the macr o hea t exchanger mo del. In- stead, evenly distr ibut ed Hex/W edge cells should b e used f or impr oved accur acy and a mor e robust solution pr ocess. •Flow acc eleration eff ects ar e neglec ted in c alcula ting the pr essur e loss c oefficien t. •For the simple eff ectiveness mo del, the pr imar y fluid must ha ve a c apacit y rate tha t is less than tha t of the auxiliar y fluid . •Auxiliar y fluid phase change c annot b e mo deled using the NTU mo del. •The macr o-based metho d requir es tha t an equal numb er of c ells r eside in each macr o of equal siz e and shap e. •The auxiliar y fluid flo w is assumed t o be 1D . •The pass width has t o be unif orm. •Accur acy is not guar anteed when the mesh is not str uctured or la yered. •Accur acy is not guar anteed when ther e is upstr eam diffusion of t emp erature at the inlet/outlet of the c ore. •Non-c onformal meshes c annot b e attached t o the inlet/outlet of the c ore. An extra layer has t o be created to avoid it. 14.3.2. Using the U ngr oup ed M acro Heat Exchanger M odel The hea t exchanger mo del settings ma y be wr itten in to and r ead fr om the b oundar y conditions file (Reading and Writing B oundar y Conditions (p.596)) using the t ext commands ,file/write-settings and file/read-settings , respectively. Other wise , the st eps f or setting up the ungr oup ed macr o heat exchanger mo del is as f ollows: 1.Read the mesh and mak e sur e tha t the inlet and outlet f or the hea t exchanger ar e two separ ate zones . 2.Enable the c alcula tion of ener gy in the Ener gy Dialog Box (p.3252 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1586Modeling H eat ExchangersSetup → Models → Energy ON 3.Enable the Ungr oup ed M acro M odel option and click the Define ... butt on in the Heat Exchanger M odel Dialog Box (p.3278 ) (Figur e 14.12: The H eat Exchanger M odel D ialog Box (p.1587 )) to acc ess the Ungr oup ed Macro Heat Exchanger dialo g box. Setup → Models → Heat Exchanger Edit... Figur e 14.12: The H eat Exchanger M odel D ialo g Box 4.Specify the hea t exchanger inputs in the Ungr oup ed M acro Heat Exchanger dialo g box. 1587Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.The M acro Heat Exchanger M odelsFigur e 14.13: The U ngr oup ed M acro H eat Exchanger D ialo g Box Displa ying the M odel D ata Tab a.In the Fluid Z one drop-do wn list , selec t the fluid z one r epresen ting the hea t exchanger c ore. b.Under the Model D ata tab , cho ose Fixed H eat Rejec tion or Fixed Inlet Temp erature, as r equir ed (Figur e 14.13: The U ngroup ed M acro Heat Exchanger D ialog Box Displa ying the M odel D ata Tab (p.1588 )). c.Specify the Heat Transf er M odel as either the default ntu-mo del or the simple-eff ectiveness- model. See st ep 3 in Choosing a H eat Exchanger M odel (p.1574 ) for details ab out the diff erences b etween these t wo mo dels . d.Specify the Core Porosit y M odel if you w ant ANSY S Fluen t to use the pr essur e loss c oefficien t func tion to aut oma tically c omput e (and up date) the p orous media c oefficien ts in the c ell z ones c ondition dialo g box, as descr ibed in Streamwise P ressur e Drop in the Theor y Guide . More inf ormation is a vailable in Setting the P ressur e-Drop P aramet ers and E ffectiveness (p.1596 ). e.If the ntu-mo del is chosen, a Heat Transf er D ata... butt on will app ear under Heat Exchanger P er- formanc e Data. Clicking the Heat Transf er D ata... butt on will op en the Heat Transf er D ata Table Dialog Box (p.3282 ), wher e you will en ter experimen tal da ta tha t defines ho w hea t transf er values r elate Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1588Modeling H eat Exchangersto the fluid flo w rates (Figur e 14.8: The H eat Transf er D ata Table D ialog Box (p.1581 )). See Specifying Heat Exchanger P erformanc e Data (p.1592 ) mor e details . Figur e 14.14: The H eat Transf er D ata Table D ialo g Box for the NTU M odel f.Enter the Auxiliar y Fluid Temp erature and the Primar y Fluid Temp erature for the ntu-mo del. These ar e the fix ed inlet t emp eratures a t which the t est w as p erformed t o obtain the hea t transf er data. g.If the simple-eff ectiveness-mo del is chosen, then click ing the Velocity Effectiveness C urve... butt on, under the Heat Exchanger P erformanc e Data, allo ws you t o set the v elocity and c orresponding ef- fectiveness f or each p oint. More inf ormation is a vailable in Specifying H eat Exchanger P erformanc e Data (p.1592 ). h.In the Geometr y tab , define the hea t exchanger macr os using the Numb er of P asses , the Numb er of Ro ws/Pass, and the Numb er of C olumns/P ass fields .The Numb er of Ro ws/Pass is along the auxiliar y flo w dir ection (heigh t) and the Numb er of C olumns/P ass is defined in the pass-t o-pass (width) dir ection. Also, enter the Auxiliar y Fluid Inlet D irection and Pass-t o-Pass D irection .You may want to snap the plane t ool to either the inlet or outlet of the hea t exchanger using the Update 1589Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.The M acro Heat Exchanger M odelsfrom P lane Tool. Note tha t the plane t ool must b e attached e xactly and or iented so tha t its gr een arrow points in the auxiliar y flo w dir ection, and its blue ar row points in the pass-t o-pass dir ection. Imp ortant To attach the plane t ool e xactly, exact coordina tes (pr inted in the c onsole b y pr obing) of the thr ee c orner no des must b e en tered in the plane t ool (x0, x1, x2) in a sp ecific order. Also, not e tha t x0 t o x1 is the auxiliar y flo w dir ection and x1 t o x2 is the pass- to-pass dir ection. More inf ormation is a vailable in Specifying the A uxiliar y Fluid Inlet and P ass-t o-Pass D irec- tions (p.1593 ) and Defining the M acros (p.1593 ). Figur e 14.15: The U ngr oup ed M acro H eat Exchanger D ialo g Box Displa ying the G eometr y Tab Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1590Modeling H eat ExchangersFigur e 14.16: The U ngr oup ed M acro H eat Exchanger D ialo g Box Displa ying the A uxiliar y Fluid Tab i.In the Auxiliar y Fluid tab , specify the Auxiliar y Fluid P roperties M etho d, either as a constan t-sp e- cific-hea t or as a user-defined-en thalp y. j.Auxiliar y Fluid F low R ate,Heat Rejec tion ,Inlet Temp erature, and Inlet P ressur e can b e pr ovided as a constan t,polynomial or piec ewise-linear profile tha t is a func tion of time . If user-defined-en- thalp y is selec ted as the Auxiliar y Fluid P roperties M etho d, you will need t o sp ecify the Inlet Qualit y and the Pressur e Drop. More inf ormation is a vailable in Specifying the A uxiliar y Fluid P rop- erties and C onditions (p.1595 ). 1591Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.The M acro Heat Exchanger M odelsk.Click Apply in the Ungr oup ed M acro Heat Exchanger dialo g box to sa ve all the settings . Onc e you click the Apply butt on, the NTU ma trix will b e comput ed fr om the r aw da ta.Therefore, mak e sur e you click Apply at the v ery end of y our setup . Imp ortant When y ou click Apply , look f or an y er ror or w arning message in the ANSY S Fluen t con- sole . Some of the c ommon er rors y ou ma y see displa yed ar e due t o the NTU c ompu- tations not c onverging . In such c ases , check tha t •you ha ve en tered the da ta correctly •the v alues of the da ta ar e reasonable •the op erating c ondition f or the auxiliar y fluid flo w rate is not t oo far fr om the r ange of the hea t transf er da ta Other er ror messages y ou ma y enc oun ter ma y be due t o macr os not getting an y cells assigned t o it. In such c ases , mak e sur e tha t •the hea t exchanger c ore is r ectangular •the dir ections ar e correct •you ar e using unif ormly spac ed c ells in b oth dir ections •the mesh is either a he xahedr a or w edge and is str uctured l.Repeat steps (a)–(k) f or an y other hea t exchanger fluid z ones . To use multiple fluid z ones t o define a single hea t exchanger , or t o connec t the auxiliar y fluid flo w path among multiple hea t exchangers , see Using the G roup ed M acro Heat Exchanger M odel (p.1598 ). For additional inf ormation, see the f ollowing sec tions: 14.3.2.1. Selec ting the Z one f or the H eat Exchanger 14.3.2.2. Specifying H eat Exchanger P erformanc e Data 14.3.2.3. Specifying the A uxiliar y Fluid Inlet and P ass-t o-Pass D irections 14.3.2.4. Defining the M acros 14.3.2.5. Specifying the A uxiliar y Fluid P roperties and C onditions 14.3.2.6. Setting the P ressur e-Drop P aramet ers and E ffectiveness 14.3.2.1. Selec ting the Z one for the H eat E xchanger Choose the fluid z one f or which y ou w ant to define a hea t exchanger in the Fluid Z one drop-do wn list. 14.3.2.2. Specifying H eat E xchanger P erformanc e Data Based on the hea t transf er mo del y ou cho ose in the Model D ata tab , some p erformanc e da ta must be en tered f or the hea t exchanger . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1592Modeling H eat Exchangers•ntu-mo del: For the ntu-mo del you will pr ovide the hea t transf er for diff erent primar y and auxiliar y fluid flow rates. Click the Heat Transf er D ata... butt on t o op en up a tabular dialo g box. Set the numb er of auxiliar y flo w rates and pr imar y fluid flo w rates.The dialo g box will r esize itself acc ordingly .You will need to pr ovide v arious pr imar y fluid flo w rates and auxiliar y fluid flo w rates and the c orresponding hea t transf er values .You ma y wr ite this da ta to a file tha t can b e read la ter. •simple-eff ectiveness-mo del: For this mo del, you will need t o pr ovide v elocity versus eff ectiveness da ta. To pr ovide this y ou c an click the Velocity Effectiveness C urve... butt on.This will op en up a tabular dialo g box. In this dialo g box, you c an set the numb er of p oints in the cur ve, then y ou c an pr ovide v elocities and corresponding eff ectiveness v alues (not e tha t the eff ectiveness v alues must b e within the r ange of 0–1). This da ta can b e wr itten t o a file and r ead back. 14.3.2.3. Specifying the A uxiliar y Fluid Inlet and P ass-t o-P ass D irections To define the auxiliar y fluid dir ection and flo w pa th, you will sp ecify dir ection v ectors f or the Auxiliar y Fluid Inlet D irection and the Pass-t o-Pass D irection in the Geometr y tab .Figur e 14.17: 1x4x3 Macros (p.1594 ) sho ws these dir ections r elative to the macr os. For some pr oblems in which the pr incipal ax es of the hea t exchanger c ore ar e not aligned with the coordina te ax es of the domain, you ma y not k now the auxiliar y fluid inlet and pass-t o-pass dir ection vectors a pr iori. In such c ases , you c an use the plane t ool as f ollows to help y ou t o det ermine these direction v ectors. 1.“Snap” the plane t ool on to the b oundar y of the hea t exchanger c ore. (Follow the instr uctions in Initializing the P lane Tool (p.2745 ) for initializing the t ool to a p osition on an e xisting sur face.) 2.Transla te and r otate the ax es of the t ool appr opriately un til the y are aligned with the pr incipal dir ections of the hea t exchanger c ore.The depth dir ection is det ermined b y the r ed axis , the heigh t dir ection b y the gr een axis , and the width dir ection b y the blue axis . 3.Onc e the ax es ar e aligned , click the Update from P lane Tool butt on in the Ungr oup ed M acro Heat Exchanger dialo g box.The dir ectional v ectors will b e set aut oma tically. (Note tha t the Update from Plane Tool butt on will also set the heigh t, width, and depth of the hea t exchanger c ore.) 14.3.2.4. Defining the M acros As discussed in The M acro Heat Exchanger M odels (p.1585 ), the fluid z one r epresen ting the hea t ex- changer c ore is split in to macr os. Macros ar e constr ucted based on the sp ecified numb er of passes , the numb er of macr o rows per pass , the numb er of macr o columns p er pass , and the c orresponding auxiliar y fluid inlet and pass-t o-pass dir ections (see Figur e 14.17: 1x4x3 M acros (p.1594 )). Macros ar e numb ered fr om to ( ) in the dir ection of auxiliar y fluid flo w, wher e is the numb er of macr os. 1593Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.The M acro Heat Exchanger M odelsFigur e 14.17: 1x4x3 M acros In the Ungr oup ed M acro H eat Exchanger dialo g box, in the Geometr y tab , specify the Numb er of Passes , the Numb er of Ro ws/Pass, and the Numb er of C olumns/P ass.The mo del will aut oma tically extrude the macr os to the depth of the hea t exchanger c ore. For each pass , the Numb er of Ro ws/Pass are defined in the dir ection of the auxiliar y flo w inlet dir ection and the Numb er of C olumns/P ass are defined in the dir ection of the pass-t o-pass dir ection. Imp ortant The Numb er of Ro ws/Pass, as w ell as the Numb er of C olumns/P ass must b e divisible b y the numb er of c ells in their r espective dir ections . For e xample , if y ou ha ve 50 c ells in the auxiliar y flo w dir ection, you c an use 25 f or the Numb er of Ro ws/Pass, but y ou should not use 26 or 24. If you ha ve 51 c ells in tha t dir ection, you c an only use 51 f or the Numb er of Rows/Pass.The same holds tr ue f or the other dir ection. 14.3.2.4.1. Viewing the M acros You c an view the auxiliar y fluid pa th b y displa ying the macr os.To view the macr os for y our sp ecified Numb er of P asses ,Numb er of Ro ws/Pass, and Numb er of C olumns/P ass, click the Apply butt on at the b ottom of the dialo g box, then click the View P asses butt on t o displa y it. The pa th of the auxiliar y fluid is c olor-c oded in the displa y: macr o is red and macr o is blue . For some pr oblems , esp ecially c omple x geometr ies, you ma y want to include p ortions of the c om- puta tional-domain mesh in y our macr os plot as spa tial r eference points. For e xample , you ma y want to sho w the lo cation of an inlet and an outlet along with the macr os.This is acc omplished b y enabling the Draw M esh option. The Mesh D ispla y Dialog Box (p.3239 ) will app ear aut oma tically when y ou enable the Draw M esh option, wher e you c an set the mesh displa y par amet ers.When y ou click the Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1594Modeling H eat ExchangersView P asses butt on in the Ungr oup ed M acro H eat Exchanger dialo g box, the mesh displa y, as defined in the Mesh D ispla y dialo g box, will b e included in the macr os plot (see Figur e 14.18: Mesh Displa y With M acros (p.1595 )). Figur e 14.18: Mesh D ispla y With M acros 14.3.2.5. Specifying the A uxiliar y Fluid P roperties and C onditions To define the auxiliar y fluid pr operties and c onditions , you will sp ecify the Auxiliar y Fluid F low R ate ( ) in the Auxiliar y Fluid tab .The pr operties of the auxiliar y fluid c an b e sp ecified using the Auxiliar y Fluid P roperties M etho d drop-do wn list. You c an cho ose a constan t-sp ecific-hea t ( ) and set the value in the Auxiliar y Fluid S pecific H eat field b elow, or as a user-defined func tion f or the en thalp y using the user-defined-en thalp y option and selec ting the c orresponding UDF fr om the Auxiliar y Fluid E nthalp y UDF drop-do wn list. The func tion should r etur n a single v alue dep ending on the inde x: •Enthalp y for giv en v alues of t emp erature, pressur e, and qualit y. •Temp erature for giv en v alues of en thalp y and pr essur e •Specific hea t for giv en v alues of t emp erature and pr essur e The user-defined func tion should b e of t ype DEFINE_SOURCE(udf_name, cell_t c, Thread *t, real d[n], int index). wher e n in the e xpression d[n] would b e 0 for temp erature,1 for pr essur e, or 2 for qualit y.The variable index is 0 for en thalp y,1 for temp erature, or 2 for sp ecific hea t.This user-defined func tion should r etur n real value; /* (temperature or enthalpy or Cp depending on index). */ 1595Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.The M acro Heat Exchanger M odels•If you w ant ANSY S Fluen t to comput e the auxiliar y fluid inlet t emp erature for a sp ecified hea t rejec tion, follow the st eps b elow: 1.Enable the Fixed H eat Rejec tion option in the Model D ata tab . 2.Specify the Heat Rejec tion ( in Equa tion 6.15 in the Theor y Guide ) in the Auxiliar y Fluid tab . 3.Specify the Initial Temp erature, which will b e used b y ANSY S Fluen t as an initial guess f or the inlet temp erature ( in Equa tion 6.11 and Equa tion 6.13 in the Theor y Guide ). •If you w ant ANSY S Fluen t to comput e the t otal hea t rejec tion of the c ore for a giv en inlet auxiliar y fluid temp erature, follow the st eps b elow: 1.Enable the Fixed Inlet Temp erature option in the Model D ata tab . 2.Specify the Inlet Temp erature ( in Equa tion 6.11 and Equa tion 6.13 in the Theor y Guide ) in the Auxiliar y Fluid tab . •If you enable the User D efined E nthalp y option under the Auxiliar y Fluid P roperties M etho d, you must also sp ecify the Inlet P ressur e ( in Equa tion 6.21 in the Theor y Guide ) and Inlet Q ualit y ( in Equa- tion 6.20 in the Theor y Guide ). 14.3.2.6. Setting the P ressur e-D rop P aramet ers and E ffec tiveness The pr essur e dr op par amet ers and eff ectiveness define the Core Porosit y M odel. If you w ould lik e ANSY S Fluen t to set the p orosity of this a hea t exchanger z one using a par ticular c ore mo del, you can selec t the appr opriate mo del. This will aut oma tically set the p orous media inputs .There ar e thr ee ways to sp ecify the Core Porosit y M odel par amet ers: •Use the v alues in ANSY S Fluen t’s default mo del. •Define a new c ore porosity mo del with y our o wn v alues . •Read a c ore porosity mo del fr om an e xternal file . If you do not cho ose a c ore porosity mo del, you will need t o set the p orosity par amet ers in the c ell zone c onditions dialo g box for the hea t exchanger z one(s). To do this , follow the pr ocedur es descr ibed in User Inputs f or P orous M edia (p.872). The mo dels y ou define will b e sa ved in the c ase file . 14.3.2.6.1. Using the D efault C ore Porosit y Mo del ANSY S Fluen t provides a default mo del f or a t ypic al hea t exchanger c ore.The default-mo del core porosity mo del is a list of c onstan t values fr om the Ungr oup ed M acro H eat Exchanger dialo g box. These c onstan ts ar e used f or setting the p orous media par amet ers.To use these v alues , simply r etain the selec tion of default-mo del in the Core Porosit y M odel drop-do wn list in the Ungr oup ed M acro Heat Exchanger dialo g box. (You c an view the default par amet ers as descr ibed b elow.) 14.3.2.6.2. Defining a N ew C ore Porosit y Mo del If you w ant to define pr essur e-dr op and eff ectiveness par amet ers tha t are diff erent from those in the default c ore porosity mo del, you c an cr eate a new mo del. The st eps f or cr eating a new mo del are as f ollows: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1596Modeling H eat Exchangers1.Click the Edit... butt on t o the r ight of the Core Porosit y M odel drop-do wn list , for which default- model should ha ve been selec ted.This will op en the Core Porosity Model D ialog Box (p.3289 ) (Fig- ure 14.19: The C ore Porosity Model D ialog Box (p.1597 )). Figur e 14.19: The C ore Porosit y M odel D ialo g Box 2.Enter the name of y our new mo del in the Name box at the t op of the dialo g box. 3.Under Gas-S ide P ressur e Drop, specify the f ollowing par amet ers used in Equa tion 6.2 in the Theor y Guide : •Minimum F low to Face Area R atio ( ) •Entranc e Loss C oefficien t ( ) •Exit L oss C oefficien t ( ) •Gas-S ide S urface Area ( ) •Minimum C ross S ection F low A rea ( ) and the Core Friction C oefficien t and Core Friction E xponen t ( and , respectively, in Equa- tion 6.3 in the Theor y Guide ). 4.Click the Change/C reate butt on.This will add y our new mo del t o the da tabase . 14.3.2.6.3. Reading H eat E xchanger P aramet ers fr om an E xternal F ile You c an r ead par amet ers f or y our Core Porosit y M odel from an e xternal file . A sample file is sho wn below: ("modelname" (0.73 0.43 0.053 5.2 0.33 9.1 0.66)) 1597Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.The M acro Heat Exchanger M odelsThe first en try in the file is the name of the mo del (f or e xample ,modelname ).The sec ond set of numb ers c ontains the gas-side (pr imar y-side) pr essur e dr op par amet ers: ( ) To read an e xternal hea t exchanger file , you will f ollow these st eps: 1.In the Core Porosit y M odel dialo g box, click the Read ... butt on. 2.In the r esulting Selec t File dialo g box, specify the HXC Paramet ers F ile name and click OK. ANSY S Fluen t will r ead the c ore porosity mo del par amet ers, and add the new mo del t o the da tabase . 14.3.2.6.4. Viewing the P aramet ers for an E xisting C ore Mo del To view the par amet ers asso ciated with a c ore porosity mo del tha t you ha ve alr eady defined , selec t the mo del name in the Database drop-do wn list (in the Core Porosit y M odel dialo g box).The v alues for tha t mo del fr om the da tabase will b e displa yed in the Core Porosit y M odel dialo g box. 14.3.3. Using the G roup ed M acro Heat Exchanger M odel To define a single hea t exchanger tha t uses multiple fluid z ones , or t o connec t the auxiliar y fluid flo w path among multiple hea t exchangers , you c an use hea t exchanger gr oups .To use hea t exchanger groups , perform the f ollowing st eps: 1.Read the mesh and mak e sur e tha t the inlet and outlet f or the hea t exchanger ar e two separ ate zones . 2.Enable the c alcula tion of ener gy in the Ener gy Dialog Box (p.3252 ). Setup → Models → Energy ON 3.Enable the Macro M odel G roup option and click the Define ... butt on in the Heat Exchanger M odel D ialog Box (p.3278 ) to acc ess the Macro Heat Exchanger G roup dialo g box. Setup → Models → Heat Exchanger Edit... 4.Specify the inputs t o the hea t exchanger gr oup in the Macro Heat Exchanger G roup dialo g box (Fig- ure 14.20: The M acro Heat Exchanger G roup D ialog Box (p.1599 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1598Modeling H eat ExchangersFigur e 14.20: The M acro H eat Exchanger G roup D ialo g Box a.Enter the Name of the hea t exchanger gr oup . b.Under Fluid Z ones , selec t the fluid z ones tha t you w ant to define in the hea t exchanger gr oup ( Selec ting the F luid Z ones f or the H eat Exchanger G roup (p.1604 )). c.Click the Model D ata tab . i.Under Primar y Fluid F low D irection , specify the pr imar y fluid flo w dir ection as either Width , Heigh t, or Depth . ii.Under Connec tivit y, selec t the Upstr eam hea t exchanger gr oup if such a c onnec tion e xists (see Selec ting the U pstr eam H eat Exchanger G roup (p.1604 )). 1599Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.The M acro Heat Exchanger M odelsiii.In the Heat Transf er M odel drop-do wn list , cho ose either the ntu-mo del or the simple-eff ective- ness-mo del. See st ep 3 in Choosing a H eat Exchanger M odel (p.1574 ) for details ab out the diff erences between these t wo mo dels . iv.From the Core Porosit y M odel drop-do wn list , specify the c ore mo del tha t should b e used t o calcula te the p orous media par amet ers f or the z ones in the gr oup . More inf ormation is a vailable in Setting the P ressur e-Drop P aramet ers and E ffectiveness (p.1596 ). v.If the ntu-mo del is chosen, a Heat Transf er D ata... butt on will app ear under Heat Exchanger Performanc e Data. Clicking the Heat Transf er D ata... butt on will op en the Heat Transf er D ata Table D ialog Box (p.3282 ), wher e you will en ter experimen tal da ta tha t defines ho w hea t transf er values r elate to the fluid flo w rates (Figur e 14.8: The H eat Transf er D ata Table D ialog Box (p.1581 )). See Specifying H eat Exchanger P erformanc e Data (p.1592 ) mor e details . Figur e 14.21: The H eat Transf er D ata Table D ialo g Box for the NTU M odel vi.Enter the Auxiliar y Fluid Temp erature and the Primar y Fluid Temp erature for the ntu-mo del. These ar e the fix ed inlet t emp eratures a t which the t est w as p erformed t o obtain the hea t transf er data. vii.If the simple-eff ectiveness-mo del is chosen, then click ing the Velocity Effectiveness C urve... butt on, under the Heat Exchanger P erformanc e Data, allo ws you t o set the v elocity and c orres- Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1600Modeling H eat Exchangersponding eff ectiveness f or each p oint. More inf ormation is a vailable in Specifying H eat Exchanger Performanc e Data (p.1592 ). d.Click the Geometr y tab ( Figur e 14.22: The M acro Heat Exchanger G roup D ialog Box - G eometr y Tab (p.1601 )). Figur e 14.22: The M acro H eat Exchanger G roup D ialo g Box - G eometr y Tab i.Define the hea t exchanger macr os b y sp ecifying the Numb er of P asses , the Numb er of Ro ws/Pass, and the Numb er of C olumns/P ass. More inf ormation is a vailable in Specifying the A uxiliar y Fluid Inlet and P ass-t o-Pass D irections (p.1593 ) and Defining the M acros (p.1593 ). ii.Specify the Auxiliar y Fluid Inlet D irection and Pass-t o-Pass D irection (see Specifying the A uxil- iary Fluid Inlet and P ass-t o-Pass D irections (p.1605 )). 1601Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.The M acro Heat Exchanger M odelse.Click the Auxiliar y Fluid tab ( Figur e 14.23: The M acro Heat Exchanger G roup D ialog Box - A uxiliar y Fluid Tab (p.1602 )) to sp ecify the auxiliar y fluid op erating c onditions . Figur e 14.23: The M acro H eat Exchanger G roup D ialo g Box - A uxiliar y Fluid Tab i.Specify the Specific H eat as either a constan t-sp ecific-hea t or as a user-defined-en thalp y. ii.Auxiliar y Fluid F low R ate,Initial Temp erature, and Inlet P ressur e can b e pr ovided as a constan t, polynomial or piec ewise-linear profile tha t is a func tion of time (see Specifying the A uxiliar y Fluid P roperties and C onditions (p.1595 )). f.If a supplemen tary auxiliar y str eam is t o be mo deled , click the Supplemen tary Auxiliar y Fluid S tream tab. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1602Modeling H eat ExchangersFigur e 14.24: The M acro H eat Exchanger G roup D ialo g Box - S upplemen tary Auxiliar y Fluid S tream Tab i.You c an sp ecify the Supplemen tary M ass F low R ate as a constan t,polynomial or piec ewise- linear profile tha t is a func tion of time . ii.You c an sp ecify the Supplemen tary Flow Temp erature as a constan t,polynomial or piec ewise- linear profile tha t is a func tion of time . 1603Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.The M acro Heat Exchanger M odelsg.Click Create or Replac e in the Macro Heat Exchanger G roup dialo g box to sa ve all the settings .Re- plac e changes the par amet ers of the alr eady existing gr oup tha t is selec ted in the HX G roups list. Imp ortant Creating or r eplacing an y hea t exchanger gr oup initializ es an y pr eviously c alcula ted values f or temp erature and en thalp y for all macr os. 5.If a hea t exchanger gr oup is c omp osed of multiple fluid z ones and y ou w ant to override an y of the inputs defined in the pr evious st eps, click the Set... butt on t o op en the Ungr oup ed M acro Heat Exchanger dialo g box (Figur e 14.13: The U ngroup ed M acro Heat Exchanger D ialog Box Displa ying the M odel D ata Tab (p.1588 )). Selec t the par ticular fluid z one as usual. Notice tha t the individual hea t exchanger inher its the pr operties of the gr oup b y default. You ma y override an y of the f ollowing: •Numb er of P asses ,Numb er of Ro ws/Pass, and Numb er of C olumns/P ass •Auxiliar y Fluid Inlet D irection and the Pass-t o-Pass D irection •Core Porosit y M odel For additional inf ormation, see the f ollowing sec tions: 14.3.3.1. Selec ting the F luid Z ones f or the H eat Exchanger G roup 14.3.3.2. Selec ting the U pstr eam H eat Exchanger G roup 14.3.3.3. Specifying the A uxiliar y Fluid Inlet and P ass-t o-Pass D irections 14.3.3.4. Specifying the A uxiliar y Fluid P roperties 14.3.3.5. Specifying Supplemen tary Auxiliar y Fluid S treams 14.3.3.6. Initializing the A uxiliar y Fluid Temp erature 14.3.3.1. Selec ting the F luid Z ones for the H eat E xchanger Gr oup Selec t the fluid z ones tha t you w ant to define in the hea t exchanger gr oup in the Fluid Z ones drop- down list. The auxiliar y fluid flo w in all these z ones will b e in par allel. Note tha t one z one c annot b e included in mor e than one hea t exchanger gr oup . 14.3.3.2. Selec ting the Upstr eam H eat E xchanger Gr oup If you w ant to connec t the cur rent group in ser ies with another gr oup , cho ose the upstr eam hea t exchanger gr oup . Note tha t an y gr oup c an ha ve at most one upstr eam and one do wnstr eam gr oup . Also, a gr oup c annot b e connec ted t o itself . Selec t a hea t exchanger gr oup fr om the Upstr eam drop- down list under Connec tivit y in the Model D ata tab of the Macro H eat Exchanger G roup dialo g box. Imp ortant Connec ting t o an upstr eam hea t exchanger gr oup c an b e done only while cr eating a hea t exchanger gr oup .The c onnec tion will p ersist e ven if the c onnec tion is la ter changed and the Replac e butt on is click ed.To change a c onnec tion t o an upstr eam hea t exchanger group , you need t o delet e the c onnec ting gr oup and cr eate a new hea t exchanger gr oup with the pr oper connec tion. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1604Modeling H eat Exchangers14.3.3.3. Specifying the A uxiliar y Fluid Inlet and P ass-t o-P ass D irections The Auxiliar y Fluid Inlet D irection and Pass-t o-Pass D irection , in the Geometr y tab c an b e sp ecified as dir ected in Specifying the A uxiliar y Fluid Inlet and P ass-t o-Pass D irections (p.1593 ) in the Ungr oup ed Macro H eat Exchanger dialo g box. Note tha t the Update fr om P lane Tool will set the heigh t, width, and depth as the a verage of the fluid z ones selec ted in the Fluid Z ones . 14.3.3.4. Specifying the A uxiliar y Fluid P roperties The auxiliar y fluid c an b e sp ecified as ha ving a constan t-sp ecific-hea t, or a user-defined func tion can b e wr itten t o calcula te the en thalp y, as descr ibed in Specifying the A uxiliar y Fluid P roperties and Conditions (p.1595 ). 14.3.3.5. Specifying S upplementar y Auxiliar y Fluid Str eams The addition or r emo val of a supplemen tary auxiliar y fluid is allo wed in an y of the hea t exchanger groups . Note tha t auxiliar y str eams ar e not allo wed f or individual z ones .You will sp ecify the mass flow rate, temp erature, and qualit y of the supplemen tary auxiliar y fluid .You will also need t o sp ecify the hea t transf er for v arious flo w rates of pr imar y and auxiliar y flo ws.The auxiliar y str eam has the following assumptions: •The magnitude of a nega tive auxiliar y str eam must b e less than the pr imar y auxiliar y fluid inlet flo w rate of the hea t exchanger gr oup . •Added str eams will b e assumed t o ha ve the same fluid pr operties as the pr imar y inlet auxiliar y fluid . 14.3.3.6. Initializing the A uxiliar y Fluid Temp eratur e When the hea t exchanger gr oup is c onnec ted t o an upstr eam hea t exchanger gr oup , ANSY S Fluen t will automa tically set the initial guess f or the auxiliar y fluid inlet t emp erature, , to be equal t o the of the upstr eam hea t exchanger gr oup .Thus the b oundar y condition for the first hea t exchanger gr oup in a c onnec ted ser ies will aut oma tically pr opaga te as an initial guess for e very other hea t exchanger gr oup in the ser ies. However, when it is nec essar y to fur ther impr ove convergenc e pr operties, you will b e allo wed t o override for an y connec ted hea t exchanger group b y pr oviding a v alue in the Initial Temp erature field .Whene ver such an o verride is supplied , ANSY S Fluen t will aut oma tically pr opaga te the new to an y hea t exchanger gr oups fur ther downstr eam in the ser ies. Similar ly, every time the boundar y condition f or the first hea t exchanger gr oup is mo dified , ANSY S Fluen t will c orrespondingly up date every do wnstr eam hea t ex- changer gr oup . If you w ant to imp ose a non-unif orm initializa tion on the auxiliar y fluid t emp erature field , first c onnec t the hea t exchanger gr oups and then set for each hea t exchanger gr oup in str eamwise or der. All hea t exchangers included in a gr oup must use the fix ed option. All hea t exchangers within a hea t exchanger gr oup must ha ve the same . In other w ords, no lo cal override of this setting is p ossible thr ough the Ungr oup ed M acro H eat Exchanger dialo g box. 1605Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.The M acro Heat Exchanger M odels14.4. Postpr ocessing f or the H eat Exchanger M odel Postpr ocessing f or the hea t exchanger mo dels in volves c omputing the t otal hea t rejec tion r ate by setting up v olume monit ors and r eporting of v ariables such as c omput ed hea t rejec tion, inlet or outlet t emp er- ature, specific hea t, and mass flo w rate. Note tha t when p ostpr ocessing dual c ell hea t exchanger mo dels using dialo g boxes other than the Heat Exchanger Rep ort dialo g box (which r equir es y ou t o explicitly sp ecify whether y ou w ant reports on either the Primar y or the Auxiliar y fluid), attention must b e paid t o the fac t tha t ther e ar e overlapping cell z ones in the hea t exchanger r egion. For e xample: •When cr eating an isosur face and mak ing selec tions fr om the From Z ones selec tion list of the Iso-S urface dialo g box, you should ne ver selec t both the pr imar y and the auxiliar y fluid z ones a t the same time . Note that if no selec tions ar e made in this list , then all the c ell z ones ar e selec ted. •When mak ing selec tions fr om the Surfaces list of the Contours dialo g box, you should not selec t a sur face that is asso ciated with the pr imar y fluid z one and a sur face asso ciated with the auxiliar y fluid z one a t the same time , if those sur faces ar e spa tially c oinciden t. For additional inf ormation, see the f ollowing sec tions: 14.4.1. Heat Exchanger R eporting 14.4.2. Total H eat Rejec tion R ate 14.4.1. Heat Exchanger Rep orting Reporting the r esults f or the hea t exchanger mo dels is done using the Heat Exchanger Rep ort dialo g box. Results → Rep orts → Heat Exchanger Edit... The f ollowing v ariable options ar e available f or reporting: •Comput ed H eat Rejec tion •Inlet Temp erature •Outlet Temp erature •Mass F low R ate •Specific H eat 14.4.1.1. Comput ed H eat R ejec tion To displa y the Comput ed H eat Rejec tion 1.Selec t Comput ed H eat Rejec tion from the Options list. 2.Selec t the Heat Exchanger from the selec tion list. 3.Click Comput e. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1606Modeling H eat ExchangersFigur e 14.25: The H eat Exchanger Rep ort Dialo g Box for Rep orting C omput ed H eat Rejec tion You c an wr ite the c omput ed da ta to a file b y click ing the Write... butt on and en tering the name of the hea t exchanger r eport file in the Selec t File dialo g box. 14.4.1.2. Inlet/O utlet Temp eratur e Inlet/Outlet Temp erature can b e reported f or b oth pr imar y and auxiliar y fluid in the Heat Exchanger Rep ort dialo g box. 1607Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Postpr ocessing f or the H eat Exchanger M odelFigur e 14.26: The H eat Exchanger Rep ort Dialo g Box for Rep orting the Inlet Temp erature 1.Selec t Inlet Temp erature or Outlet Temp erature from the Options list. 2.Selec t the hea t exchanger fr om the Heat Exchanger selec tion list. 3.Selec t either Auxiliar y or Primar y as the Fluid Z one . 4.Selec t the appr opriate boundar y zone and r eport type from the Boundar y and Rep ort Type lists , respect- ively. Imp ortant Note tha t the macr o hea t exchangers (unlik e the dual c ell hea t exchanger) do not contain an auxiliar y cell z one . Hence, the Boundar y and Rep ort Type fields will not app ear in the dialo g box if y ou ar e reporting an auxiliar y inlet/outlet t emp erature. 5.Click Comput e. You c an wr ite the c omput ed da ta to a file b y click ing the Write... butt on and en tering the name of the hea t exchanger r eport file in the Selec t File dialo g box. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1608Modeling H eat Exchangers14.4.1.3. Mass F low R ate Mass F low R ate can b e reported f or b oth the pr imar y and auxiliar y fluid in the Heat Exchanger Rep ort dialo g box. Figur e 14.27: The H eat Exchanger Rep ort Dialo g Box for Rep orting M ass F low R ate 1.Selec t Mass F low R ate from the Options group b ox. 2.Selec t the hea t exchanger fr om the Heat Exchanger selec tion list. 3.Selec t either Auxiliar y or Primar y as the Fluid Z one . 4.Selec t the appr opriate boundar y zone and r eport type from the Boundar y and Rep ort Type lists , respect- ively. 5.Click Comput e. Imp ortant Note tha t the macr o hea t exchangers (unlik e the dual c ell hea t exchanger) do not c ontain an auxiliar y cell z one . Hence, the Boundar y field will not app ear in the dialo g box if y ou are reporting an auxiliar y fluid mass flo w rate. You c an wr ite the c omput ed da ta to a file b y click ing the Write... butt on and en tering the name of the hea t exchanger r eport file in the Selec t File dialo g box. 1609Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Postpr ocessing f or the H eat Exchanger M odel14.4.1.4. Specific H eat Specific H eat for the pr imar y or auxiliar y fluid c an b e reported thr ough the Heat Exchanger Rep ort dialo g box. If specific hea t is defined as a func tion of t emp erature, the sp ecific hea t reported will b e a cell v olume a veraged v alue . Figur e 14.28: The H eat Exchanger Rep ort Dialo g Box for Rep orting S pecific H eat 1.Selec t Specific H eat from the Options group b ox. 2.Selec t the hea t exchanger fr om the Heat Exchanger selec tion list. 3.Selec t either Auxiliar y or Primar y as the Fluid Z one . 4.Click Comput e. 14.4.2. Total H eat Rejec tion R ate To postpr ocess the t otal hea t rejec tion r ate, you c an set up a v olume r eport definition t o monit or convergenc e and view the c omput ed v alues . Solution → Rep orts → Definitions → New → Volume Rep ort → Sum... 1.Selec t Temp erature and Heat Exchanger S our ce from the Field Variables drop-do wn lists . 2.Selec t the appr opriate Cell Z ones and click OK to close the Volume M onit or dialo g box. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1610Modeling H eat ExchangersFigur e 14.29: The Volume Rep ort Definition D ialo g Box Imp ortant Note tha t the macr o hea t exchangers c ontain only the pr imar y fluid as the c ell z one , but in case of the dual c ell mo del, you c an selec t either the pr imar y or auxiliar y fluid . 14.5. Useful Rep orting TUI C ommands To report the r esults f or the macr o hea t exchangers , you c an use the f ollowing t ext command: define → models → heat-exchanger → macro-model → heat-exchanger-macro-report Specify the fluid z one for which y ou w ant to obtain inf ormation. To view the c onnec tivit y of the hea t exchanger gr oups , use the t ext command: (report-connectivity) 1611Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Useful R eporting TUI C ommandsRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1612Chapt er 15: Modeling S pecies Transp ort and F inite-Rate Chemistr y Species tr ansp ort mo deling c apabilities , both with and without r eactions , and the inputs y ou pr ovide when using the mo del ar e descr ibed in this chapt er. For theor etical inf ormation ab out sp ecies tr ansp ort, see Species Transp ort and F inite-Rate Chemistr y in the Theor y Guide . Note tha t you ma y also w ant to consider mo deling y our turbulen t reacting flame using one of the f ol- lowing appr oaches: •Mixture fraction appr oach f or non-pr emix ed sy stems ( Modeling N on-P remix ed C ombustion (p.1687 )) •Reaction pr ogress v ariable appr oach f or pr emix ed sy stems ( Modeling P remix ed C ombustion (p.1749 )) •Partially pr emix ed appr oach ( Modeling P artially P remix ed C ombustion (p.1759 )) •Comp osition PDF Transp ort appr oach ( Modeling a C omp osition PDF Transp ort Problem (p.1779 )) •Multiphase sp ecies tr ansp ort and finit e-rate chemistr y (Modeling M ultiphase F lows (p.2091 )) For simula tions using ANSY S Fluen t reacting flo w mo dels , you c an sp ecify mix tures c onsisting of up t o 700 chemic al sp ecies . The f ollowing mo dels and f eatures ma y not b e used with mor e than 50 sp ecies: •Densit y-based solv er •Euler ian PDF Transp ort mo del •Melting/solidific ation mo del •Crevice mo del •Thermal diffusivit y mo del •Surface sp ecies •Site sp ecies Note If the sp ecies mo del is used in c ombina tion with a multihpase mo del, the mass fr action of a sp ecies ma y be displa yed inc orrectly in ANSY S CFD-P ost if the v olume fr action of a c ell is zero.This applies f or all ANSY S Fluen t files wr itten pr ior t o release 2019 R3. For all multiphase , multi-sp ecies c ases cr eated in r elease 19.2 and b eyond , the mass fr actions of sp ecies will not b e available in ANSY S CFD-P ost, unless y ou add the mass fr action of a species as an additional quan tity to be sa ved in the da ta file (thr ough the Data F ile Q uan t- ities dialo g box). Information is divided in to the f ollowing sec tions: 15.1. Volumetr ic Reactions 15.2. Wall Sur face Reactions and C hemic al Vapor D eposition 1613Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.15.3. Particle Sur face Reactions 15.4. Electrochemic al Reactions 15.5. Species Transp ort Without R eactions 15.6. Reacting C hannel M odel 15.7. Reactor N etwork Model 15.1. Volumetr ic Reac tions Information ab out using sp ecies tr ansp ort and finit e-rate chemistr y as r elated t o volumetr ic reactions is pr esen ted in the f ollowing subsec tions . For mor e inf ormation ab out the theor etical back ground of volumetr ic reactions , see Volumetr ic Reactions in the Theor y Guide . 15.1.1. Overview of U ser Inputs f or M odeling S pecies Transp ort and R eactions 15.1.2. Enabling S pecies Transp ort and R eactions and C hoosing the M ixture Material 15.1.3. Imp orting a Volumetr ic Kinetic M echanism in CHEMKIN F ormat 15.1.4. Defining P roperties f or the M ixture and I ts Constituen t Species 15.1.5. Setting up C oal S imula tions with the C oal C alcula tor D ialog Box 15.1.6. Defining C ell Z one and B oundar y Conditions f or Species 15.1.7. Defining O ther S ources of C hemic al Species 15.1.8. Solution P rocedur es for C hemic al M ixing and F inite-Rate Chemistr y 15.1.9. Postpr ocessing f or Species C alcula tions 15.1.1. Overview of U ser Inputs f or M odeling S pecies Transp ort and Reac tions The basic st eps f or setting up a pr oblem in volving sp ecies tr ansp ort and r eactions ar e list ed b elow. 1.Selec t species tr ansp ort and v olumetr ic reactions , and sp ecify the mix ture ma terial. See Enabling S pecies Transp ort and R eactions and C hoosing the M ixture Material (p.1616 ).The mix ture ma terial c oncept is e x- plained in Mixture Materials (p.1615 ). 2.If you ar e also mo deling w all or par ticle sur face reactions , selec t wall sur face and/or par ticle sur face reac- tions . See Wall Sur face Reactions and C hemic al Vapor D eposition (p.1654 )Particle Sur face Reactions (p.1661 ) for details . 3.Check and/or define the pr operties of the mix ture. See Defining P roperties f or the M ixture and I ts Con- stituen t Species (p.1629 ). Mixture pr operties include the f ollowing: •species in the mix ture •reactions •other ph ysical pr operties (f or e xample , visc osity, specific hea t) 4.Check and/or set the pr operties of the individual sp ecies in the mix ture. See Defining P roperties f or the Mixture and I ts Constituen t Species (p.1629 ). 5.Set sp ecies c ell z one and b oundar y conditions . See Defining C ell Z one and B oundar y Conditions f or S pe- cies (p.1649 ). In man y cases , you will not need t o mo dify an y ph ysical pr operties of mix ture ma terial b ecause the solv er gets sp ecies pr operties, reactions , and so on, from the ma terials da tabase when y ou cho ose the mixture ma terial. Some pr operties, however, ma y not b e defined in the da tabase .You will b e warned when y ou cho ose y our ma terial if an y requir ed pr operties need t o be set , and y ou c an then assign appr opriate values f or these pr operties.You ma y also w ant to check the da tabase v alues of other Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1614Modeling S pecies Transp ort and F inite-Rate Chemistr yproperties t o be sur e tha t the y are correct for y our par ticular applic ation. For details ab out mo difying an e xisting mix ture ma terial or cr eating a new one fr om nothing , see Defining P roperties f or the M ixture and I ts C onstituen t Species (p.1629 ). Modific ations t o the mix ture ma terial c an include the f ollowing: •Addition or r emo val of sp ecies •Changing the chemic al reactions •Modifying other ma terial pr operties f or the mix ture •Modifying ma terial pr operties f or the mix ture’s constituen t species If you ar e solving a r eacting flo w, you will usually w ant to define the mix ture’s sp ecific hea t as a func tion of c omp osition, and the sp ecific hea t of each sp ecies as a func tion of t emp erature.You ma y want to do the same f or other pr operties as w ell. By default , most sp ecies sp ecific hea ts in the da tabase are piec ewise-p olynomial func tions of t emp erature, but y ou ma y cho ose t o sp ecify a diff erent temp er- ature-dep enden t func tion if y ou k now of one tha t is mor e suitable f or y our pr oblem. 15.1.1.1. Mixture M aterials The c oncept of mix ture ma terials has b een implemen ted in ANSY S Fluen t to facilita te the setup of species tr ansp ort and r eacting flo w. A mix ture ma terial ma y be though t of as a set of sp ecies and a list of r ules go verning their in teraction. The mix ture ma terial c arries with it the f ollowing inf ormation: •A list of the c onstituen t species , referred t o as “fluid ” materials •A list of mixing la ws dic tating ho w mix ture pr operties (densit y, visc osity, specific hea t, and so on) ar e to be der ived fr om the pr operties of individual sp ecies if c omp osition-dep enden t properties ar e desir ed •A dir ect specific ation of mix ture pr operties if c omp osition-indep enden t properties ar e desir ed •Diffusion c oefficien ts for individual sp ecies in the mix ture •Other ma terial pr operties (f or e xample , absor ption and sc attering c oefficien ts) tha t are not asso ciated with individual sp ecies •A set of r eactions , including a r eaction t ype (finit e-rate, edd y-dissipa tion, and so on) and st oichiometr y and r ate constan ts The mix ture ma terials ar e stored in the ANSY S Fluen t ma terials da tabase . Many common mix ture materials ar e included (f or e xample , methane-air , propane-air). Gener ally, one or t wo-st ep r eaction mechanisms and man y ph ysical pr operties of the mix ture and its c onstituen t sp ecies ar e defined in the da tabase . The ANSY S Fluen t ma terials da tabase is acc essed in one of t wo ways, dep ending on the sequenc e of your w orkflow: •through the Species M odel dialo g box before an y one of the sp ecies mo dels is enabled •through the Create/Edit M aterials dialo g box after one of the a vailable sp ecies mo dels is enabled When y ou enable one of the sp ecies mo dels , the mix ture ma terial tha t you ha ve selec ted f or y our applic ation, its c onstituen t fluid ma terials, and pr operties will b e loaded in to your simula tion. If an y necessar y inf ormation ab out the selec ted ma terial (or the c onstituen t fluid ma terials) is missing , the solv er will inf orm y ou tha t you need t o sp ecify it. In addition, you ma y cho ose t o mo dify an y of the 1615Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Volumetr ic Reactionspredefined pr operties. See Using the Create/Edit M aterials Dialog Box (p.1081 ) for inf ormation ab out the sour ces of ANSY S Fluen t da tabase pr operty da ta. For e xample , if y ou plan t o mo del c ombustion of a methane-air mix ture using global k inetics , you do not need t o explicitly sp ecify the sp ecies in volved in the r eaction or the r eaction itself .You will simply selec t methane-air as the mix ture ma terial t o be used , and the r elevant sp ecies (CH4, O2, CO2, H2O, and N2) and r eaction da ta will b e loaded in to the solv er fr om the da tabase .You c an then check the sp ecies , reactions , and other pr operties and define an y pr operties tha t are missing and/or mo dify any pr operties f or which y ou w ant to use diff erent values or func tions .You will gener ally w ant to define a c omp osition- and t emp erature-dep enden t sp ecific hea t, and y ou ma y want to define addi- tional pr operties as func tions of t emp erature and/or c omp osition. The use of mix ture ma terials giv es y ou the fle xibilit y to selec t and load fr om the F luen t da tabase one of the man y pr edefined mix tures tha t is appr opriate for y our c ase or , if y ou w ant to cr eate your o wn cust om mix ture ma terial, a mix ture-templa te (the default) c onsisting of H2O, O2, and N2. Onc e the mixture ma terial has b een c opied t o the solv er, you c an mo dify it in the Create/Edit M aterials D ialog Box (p.3386 ), as descr ibed in Defining P roperties f or the M ixture and I ts C onstituen t Species (p.1629 ). 15.1.2. Enabling S pecies Transp ort and Reac tions and C hoosing the M ixture Material The pr oblem setup f or sp ecies tr ansp ort and v olumetr ic reactions b egins in the Species M odel dialo g box (Figur e 15.1: The S pecies M odel D ialog Box (p.1617 )). For c ases tha t involve multiphase sp ecies transp ort and r eactions , refer to Modeling S pecies Transp ort in M ultiphase F lows in the Theor y Guide . Setup → Models → Species Edit... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1616Modeling S pecies Transp ort and F inite-Rate Chemistr yFigur e 15.1: The S pecies M odel D ialo g Box 1.Under Model, selec t Species Transp ort. 2.Under Reac tions , selec t Volumetr ic. 3.In the Mixture M aterial drop-do wn list under Mixture Properties , selec t which mix ture ma terial y ou want to use in y our pr oblem or , if you w ant to create your o wn mix ture ma terial, retain the default selec tion of mix ture-templa te consisting of H2O, O2, and N2.The dr op-do wn list includes all of the mix tures tha t are cur rently defined in the da tabase . If ther e is a mix ture ma terial list ed tha t is similar t o your desir ed mixture, you ma y cho ose tha t ma terial and mo dify it f ollowing the st eps pr ovided in Defining P roperties for the M ixture and I ts Constituen t Species (p.1629 ). 1617Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Volumetr ic ReactionsThe numb er of sp ecies in the selec ted mix ture ma terial is displa yed in the Numb er of Volumetr ic Species field and , if applic able , in the Numb er of S olid S pecies and Numb er of S ite Species fields .To review the mix ture comp osition and r eactions of the selec ted F luen t da tabase mix ture material, click the View... butt on t o the r ight of Mixture M aterial.This op ens the Fluen t Database Materials dialo g box. Clicking, in tur n, the View... butt ons ne xt to Mixture Species and Reac tion opens the c orresponding dialo g boxes allo wing y ou t o examine the c onstituen t sp ecies and r eactions data. Note, tha t the mix ture pr operties c annot b e edit ed b efore the mix ture ma terial is c opied t o your F luen t problem. For this r eason, all r elated c ontrols ar e dimmed while viewing the mix ture properties. When y ou enable the sp ecies tr ansp ort mo del b y click ing either OK or Apply , ANSY S Fluen t performs the f ollowing: •The selec ted F luen t da tabase mix ture ma terial including all c onstituen t fluid ma terials (sp ecies) and pr operties ar e aut oma tically c opied t o your c ase and app ear under Mixture in the tr ee and the Materials task page . •If an y pr operties f or the selec ted mix ture ma terial (or the c onstituen t fluid ma terials) ar e missing , the solv er pr ints to the c onsole a notic e of the r equir ed da ta. •When the mix ture ma terial is c opied , the Mixture M aterial drop-do wn list in the Species M odel dialo g box changes t o contain only the mix tures defined f or y our F luen t problem. •The View... butt on is r eplac ed b y the Edit... butt on giving y ou an option t o acc ess the Edit Material dialo g box (Edit M aterial D ialog Box (p.3442 )) from the Species M odel dialo g box. •The Create/Edit M aterials dialo g box lists mix ture in the Material Type drop-do wn list allo wing you t o acc ess the F luen t mix ture ma terial da tabase . If you w ant to check or mo dify an y pr operties of the mix ture ma terial, use the Create/Edit M aterials D ialog Box (p.3386 ), as descr ibed in Defining Properties f or the M ixture and I ts C onstituen t Species (p.1629 ). You c an add mor e mix ture ma terials t o your c ase b y copying them fr om the da tabase , as descr ibed in Copying M aterials fr om the ANSY S Fluen t Database (p.1084 ), or b y creating a new mix ture, as descr ibed in Creating a N ew M aterial (p.1086 ) and Defining P roperties f or the M ixture and I ts C on- stituen t Species (p.1629 ). 4.Selec t the Turbulenc e-Chemistr y In teraction (TCI) mo deling option. The following options ar e available: Finit e-Rate/N o TCI comput es only the A rrhenius r ate (see Equa tion 7.7 in the Theor y Guide ) and neglec ts turbulenc e- chemistr y interaction. This mo del is r ecommended f or laminar or turbulen t flo ws using c omple x chemistr y wher e either the turbulenc e time-sc ales ar e expected t o be fast r elative to the chemistr y time sc ales or wher e the chemistr y is sufficien tly c omple x tha t the chemistr y timesc ales of imp ortanc e are highly dispar ate thr oughout the simula tion. You c an sp ecify the f ollowing inputs: Flow Iterations p er C hemistr y Update (stead y-sta te only) Increasing the numb er reduc es the c omputa tional e xpense of the chemistr y calcula tions . By default , ANSY S Fluen t will up date the chemistr y onc e per flo w iteration. This option is not a vailable when the None - E xplicit S our ce option is selec ted f or Chemistr y Solver. Aggr essiv eness F actor (stead y-sta te only) This is a numer ical fac tor tha t controls the r obustness and the c onvergenc e sp eed.This v alue ranges b etween 0 and 1, wher e 0 is the most r obust , but r esults in the slo west c onvergenc e.The Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1618Modeling S pecies Transp ort and F inite-Rate Chemistr ydefault v alue f or the Aggr essiv eness F actor is 0.5. This option is a vailable only when Stiff Chemistr y Solver or CHEMKIN CFD S olver is selec ted f or Chemistr y Solver. Temp erature Threshold (stead y-sta te only) The r eaction r ate is highly t emp erature-dep enden t.When t emp erature is lo w, the r eaction r ate is fair ly small and c an b e ignor ed.This ma y reduc e the c omputa tional c ost without sacr ificing ac- curacy. ANSY S Fluen t sets the chemistr y reaction r ate to zero in c ells wher e temp erature is b elow the Temp erature Threshold you sp ecified .The default v alue is 200 K. This option is a vailable only when Stiff C hemistr y Solver or CHEMKIN CFD S olver is selec ted f or Chemistr y Solver. Finit e-Rate/Eddy-D issipa tion (turbulen t flo ws only) comput es b oth the A rrhenius r ate and the mixing r ate and uses the smaller of the t wo. Eddy-D issipa tion (turbulen t flo ws only) comput es only the mixing r ate (see Equa tion 7.25 and Equa tion 7.26 in the Theor y Guide ). Eddy-D issipa tion C onc ept (turbulen t flo ws only) models turbulenc e-chemistr y interaction with detailed chemic al mechanisms (see Equa tion 7.7 and Equa tion 7.30 in the Theor y Guide ).When using this mo del, you c an mo dify the f ollowing: Flow Iterations p er C hemistr y Update (stead y-sta te only) Increasing the numb er reduc es the c omputa tional e xpense of the chemistr y calcula tions . By default , ANSY S Fluen t will up date the chemistr y onc e per flo w iteration. Aggr essiv eness F actor (stead y-sta te only) This is a numer ical fac tor tha t controls the r obustness and the c onvergenc e sp eed.This v alue ranges b etween 0 and 1, wher e 0 is the most r obust , but r esults in the slo west c onvergenc e.The default v alue f or the Aggr essiv eness F actor is 0.5. Temp erature Threshold (stead y-sta te only) The r eaction r ate is highly t emp erature-dep enden t.When t emp erature is lo w, the r eaction r ate is fair ly small and c an b e ignor ed.This ma y reduc e the c omputa tional c ost without sacr ificing ac- curacy. ANSY S Fluen t sets the chemistr y reaction r ate to zero in c ells wher e temp erature is b elow the Temp erature Threshold you sp ecified .The default v alue is 200 K. Volume F raction C onstan t,Time Sc ale C onstan t in Equa tion 7.28 and in Equa tion 7.29 in the Theor y Guide .The default v alues ar e recommen- ded . 5.From the Chemistr y Solver drop-do wn list , selec t the solv er for y our simula tion (not e tha t the solv ers available in the dr op-do wn list ar e dep endan t on the selec ted Turbulenc e-Chemistr y In teraction mo del): •If you w ant the stiff chemistr y to relax t o chemic al equilibr ium without solving r eactions , selec t Relax to Chemic al E quilibr ium .This option is not a vailable f or Eddy Dissipa tion C onc ept. For inf ormation about the R elaxa tion t o Chemic al Equilibr ium mo del, refer to The R elaxa tion t o Chemic al Equilibr ium Model in the Theor y Guide Imp ortant The Relax t o Chemic al E quilibr ium chemistr y solv er requir es ther modynamic da ta of all sp ecies t o calcula te chemic al equilibr ium. You c an supply y our o wn da tabase using the Imp ort CHEMKIN F ormat Mechanism dialo g box (op ened b y click ing Imp ort CHEMKIN mechanism... ) (see Imp orting a Volumetr ic Kinetic M echanism in CHEMKIN 1619Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Volumetr ic ReactionsFormat (p.1624 ) and Imp orting a Sur face Kinetic M echanism in CHEMKIN F ormat (p.1655 ) for details). A sample da tabase is also c ontained in the file .../flu- entx.x/cpropep/data/thermo.db . If you define y our o wn sp ecies in ANSY S Fluen t, as det ermined b y the Chemic al F ormula in the Create/Edit M aterials dialo g box, and this sp ecies name is not in the ther mo.db file , ANSY S Fluen t will r eport an error.To overcome this er ror, you must manually en ter all the unk nown sp ecies in the ther mo file . •If you w ant to solv e finit e-rate chemistr y, selec t either Stiff C hemistr y Solver or CHEMKIN-CFD S olver. These t wo solv ers ar e available when using the Finit e-Rate/N o TCI or Eddy-D issipa tion C onc ept TCI option. Selec ting CHEMKIN-CFD S olver will enable y ou t o use the ANSY S CHEMKIN-CFD solution al- gorithms , which ar e based on and c ompa tible with the ANSY S Chemk in-P ro technolo gy. Onc e you click OK or Apply , you will b e pr ompt ed t o imp ort a CHEMKIN mechanism, if y ou ha ve not already done so . Refer to the ANSY S Chemk in-P ro Input and Theor y manuals f or details on the chemistr y formula tion options . See Using ANSY S Encr ypted M echanisms (p.1625 ) for instr uctions on establishing a CHEMKIN-mechanism based ma terial. In addition, Appendix C: Controlling CHEMKIN-CFD S olver P aramet ers U sing Text Commands (p.3989 ) includes inf ormation ab out ad- vanced solv er settings and diagnostic inf ormation f or the CHEMKIN-CFD solv er.With the Chemk in- CFD S olver selec ted, the metho ds for mix ture ma terial pr operties will b e default ed t o chemk in. See Procedur e for Imp orting Volumetr ic CHEMKIN M echanisms (p.1625 ) for details . •If you w ant to mak e explicit use of chemistr y sour ce terms in the sp ecies tr ansp ort equa tions , without a stiff-chemistr y solv er, selec t None - E xplicit S our ce.This solv er is not r ecommended f or stiff or comple x chemistr y. 6.(optional) F or TCI mo del options tha t consider finit e-rate chemistr y, set the in tegration par amet ers using the Integration P aramet ers dialo g box (op ened b y click ing the Integration P aramet ers... butt on). In the Integration P aramet ers dialo g box, you c an selec t acc eleration metho ds (see Using C hemistr y Accel- eration (p.1793 ) for mor e details): •Dynamic M echanism Reduc tion (DMR) (f or Stiff C hemistr y Solver): See Using D ynamic M echanism Reduc tion (p.1797 ) for details . •Chemistr y Agglomer ation (CA) (f or Stiff C hemistr y Solver and Relax t o Chemic al E quilibr ium ): See Using C hemistr y Agglomer ation (p.1802 ) for details . •ISAT: See Using ISA T (p.1794 ) for details . •Dynamic C ell C lust ering (DC C) (f or the CHEMKIN-CFD S olver): See see Using D ynamic C ell C luster- ing (p.1803 ) for details . 7.(optional) S elec t an y Options desir ed. If you w ant to mo del full multic omp onen t (Stefan-M axwell) diffusion or ther mal (S oret) diffusion, selec t the Full M ultic omp onen t Diffusion or Thermal D iffusion option, respectively. See Full M ultic omp onen t Diffusion (p.1142 ) for details . 8.Enable the Thick ened F lame M odel when mo deling unst eady laminar flames , or when using an LES model f or turbulen t premix ed and par tially-pr emix ed flames . In the Thick ened F lame M odel Options group b ox, specify : Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1620Modeling S pecies Transp ort and F inite-Rate Chemistr y•Numb er of G rid P oints in F lame : Default is 8 gr id p oints. •(simula tions with LES only) Integral L ength Sc ale: Is the r epresen tative of the lar gest edd y siz es, in Equa tion 7.35 in the Fluent Theor y Guide .You should pr ovide a v alue based on the geometr y and siz e of the char acteristic b odies (such as inlet , bur ners , or bluff b odies). Typic ally, a value r anging fr om 1/4 to 1/2 of the char acteristic dimension is used . Consequen tly, in the Create/Edit M aterials dialo g box, you will sp ecify the Laminar F lame S peed , for which y ou ha ve a choic e of constan t,user-defined , or met ghalchi-k eck-la w, and the Laminar Flame Thick ness , for which y ou ha ve a choic e of constan t,user-defined , or diffusivit y-over- flame-sp eed . Note Since the thick ened flame mo del must c aptur e the c orrect flame sp eed, it is imp er- ative tha t the c ombina tion of y our chemic al mechanism and y our molecular tr ansp ort properties (diffusion c oefficien ts and ther mal c onduc tivit y) reproduce the c orrect laminar flame sp eed. It is r ecommended tha t you v erify this with a 1D pr emix ed flame simula tion using ANSY S Chemk in-P ro, for e xample . When the Thick ened F lame M odel is enabled ( Figur e 15.2: The S pecies M odel D ialog Box Displa ying the Thick ened F lame M odel (p.1622 )), you ha ve the option t o ho ok a UDF in the User-D efined Func tion H ooks dialo g box to cust omiz e the Thick ened F lame M odel par amet ers. Refer to DEFINE_THICKENED_FLAME_MODEL in the Fluent C ustomization Manual for details . Imp ortant The Thick ened F lame M odel is a vailable only f or unst eady laminar or turbulen t (LES / DES / SAS / SBES / SDES) flo ws, with Species Transp ort and Volumetr ic Reac tions enabled . For inf ormation ab out the theor y behind the Thick ened F lame M odel, refer to The Thick ened Flame M odel in the Theor y Guide . 1621Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Volumetr ic ReactionsFigur e 15.2: The S pecies M odel D ialo g Box Displa ying the Thick ened F lame M odel The S pecies M odel D ialog Box 9.(optional) S elec t the sp ecies f or which y ou w ant to sp ecify b oundar y conditions . Only the sp ecies tha t you ha ve selec ted will b e list ed in the r elevant boundar y condition dialo g boxes.This will facilita te the problem setup , esp ecially when a lar ge numb er of sp ecies ar e used in a gas mix ture. Note tha t the Patch and Hybr id Initializa tion dialo g boxes, as w ell as the Solution Initializa tion task page will also displa y only the selec ted sp ecies . a.Click Selec t Boundar y Species . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1622Modeling S pecies Transp ort and F inite-Rate Chemistr yFigur e 15.3: The S elec t Boundar y Species D ialo g Box By default , all the gas sp ecies f or which the tr ansp ort equa tions ar e to be applied ar e set as boundar y sp ecies and app ear in the Selec ted multiple-selec tion list of the Selec t Boundar y Species dialo g box (see Figur e 15.3: The S elec t Boundar y Species D ialog Box (p.1623 )). b.Modify the b oundar y sp ecies list as f ollows: •To remo ve the sp ecies fr om the Selec ted S pecies multiple-selec tion list , selec t it and click Remo ve. The sp ecies will b e mo ved fr om the Selec ted S pecies list t o the Unselec ted S pecies list. •To add the sp ecies back t o the Selec ted S pecies list, simply selec t it in the Unselec ted S pecies multiple-selec tion list and click Add.The sp ecies will b e mo ved fr om the Unselec ted S pecies list to the Selec ted S pecies list. 10.(optional) In a similar manner , click the Selec t Rep orted Residuals butt on and selec t the sp ecies tha t you w ant to monit or. Only the r esiduals f or the selec ted sp ecies will b e monit ored and plott ed in the graphics windo w dur ing the simula tion. 1623Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Volumetr ic ReactionsFigur e 15.4: The S elec t Residual M onit ored S pecies By default , all the sp ecies f or which the sp ecies tr ansp ort equa tions ar e to be solv ed ar e set as monit ored sp ecies , and their r esidual plots will b e dr awn in the gr aphics windo w dur ing the r un. For a lar ge numb er of monit ored sp ecies , it ma y be difficult t o distinguish the o verlapping plot lines . By decr easing the numb er of monit ored sp ecies , you c an obtain clear er residual plots . Imp ortant •The F luen t solv er p erforms the c onvergenc e checks only f or the monit ored sp ecies .To pr event false c onvergenc e, mak e sur e to include the sp ecies tha t ma y ha ve difficulties c onverging in the monit ored sp ecies list. •You c an mo dify the list of the monit ored sp ecies d ynamic ally dur ing a r un. 15.1.3. Imp orting a Volumetr ic K inetic M echanism in CHEMKIN F ormat You c an imp ort gas k inetics mechanism in CHEMKIN f ormat, which c an b e used with an y solv er option. For the CHEMKIN-CFD S olver, native CHEMKIN c omputa tions will det ermine r eaction r ates, so full compa tibilit y with ANSY S Chemk in-P ro is pr ovided . Note If a mechanism includes a t least one r eaction t ype tha t is not supp orted in the F luen t ma- terial-definition in terface (tha t is, it is not included in the options f or manual setup of r eac- tions), the r eactions of the CHEMKIN mechanism will not b e displa yed in the F luen t interface, even though the y will b e correctly used in F luen t computa tions . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1624Modeling S pecies Transp ort and F inite-Rate Chemistr y15.1.3.1. Using ANSY S Encr ypt ed Mechanisms For c ertain t ypes of simula tions , Fluen t supp orts the use of encr ypted gas k inetics mechanisms , such as those der ived fr om the ANSY S M odel F uels Libr ary (encr ypted) or thr ough ANSY S ser vices. In or der to use an encr ypted mechanism, you must first imp ort both the gas-phase k inetics and ther modynamic files as descr ibed in Procedur e for Imp orting Volumetr ic CHEMKIN M echanisms (p.1625 ). When using encr ypted CHEMKIN gas mechanisms , not e the f ollowing p oints: •Encr ypted mechanisms c an only b e used with the CHEMKIN-CFD solv er or the Relax t o Chemic al E quilib- rium option •Prior t o imp orting a flamelet or r eading a PDF table gener ated with an encr ypted mechanism, you must first imp ort the mechanism •Chemic al equilibr ium PDF table gener ation is not supp orted •Multiphase and D ecoupled D etailed C hemistr y mo dels ar e not supp orted •You c annot c ombine encr ypted and plain-t ext gas k inetics , surface kinetics and ther modynamics files in a simula tion •The chemistr y acc eleration options D ynamic M echanism R educ tion (DMR) and D imension R educ tion (DR) are not supp orted. Note The pr oprietar y reaction da ta will not b e displa yed in the F luen t interface. 15.1.3.2. Procedur e for Imp orting Volumetric CHEMKIN Mechanisms You c an imp ort the CHEMKIN mechanism file in to ANSY S Fluen t using the Imp ort CHEMKIN F ormat Mechanism dialo g box (Figur e 15.5: The Imp ort CHEMKIN F ormat Mechanism D ialog Box for Volumetr ic Kinetics (p.1626 )) (op ened b y click ing Imp ort CHEMKIN M echanism... in the Species M odel dialo g box). 1625Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Volumetr ic ReactionsFigur e 15.5: The Imp ort CHEMKIN F ormat Mechanism D ialo g Box for Volumetr ic K inetics In the Imp ort CHEMKIN F ormat Mechanism dialo g box 1.Enter a name f or the chemic al mechanism under Material N ame . 2.Enter the pa th to the CHEMKIN file (f or e xample ,path/file .inp ) in the Kinetics Input F ile text field in the Gas-P hase group b ox. Imp ortant Since ANSY S Fluen t do es not solv e for the last sp ecies , you must ensur e tha t the last species in the CHEMKIN mechanism sp ecies list is an abundan t sp ecies , such as nitr ogen. If not , edit the CHEMKIN mechanism file b efore imp orting it in to ANSY S Fluen t, and move the most abundan t sp ecies (tha t is the sp ecies in y our sy stem with the lar gest total mass fr action) t o the end of the sp ecies list. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1626Modeling S pecies Transp ort and F inite-Rate Chemistr y3.Specify sp ecies ther modynamic pr operty da ta.You c an include the da ta in the k inetics input file and/or in a separ ate file as f ollows: •If you w ant to sp ecify ther modynamic da ta for all sp ecies in the k inetics input file , enable All contained in K inetics Input F ile to avoid the need t o sp ecify a separ ate file . •If you pr ovide some or all sp ecies ther modynamic da ta in a separ ate file , disable All contained in Kinetics Input F ile and sp ecify the ther modynamic da ta file lo cation. You c an either use the default ther modynamic da tabase file ,thermo.db , provided in the cpropep\data directory in y our ANSY S Fluen t installa tion ar ea or sp ecify the pa th of y our ther modynamic da tabase file if thermo.db does not c ontain all the gas-phase sp ecies in the CHEMKIN mechanism. The f ormat for thermo.db is detailed in the CHEMKIN manual [59] (p.4008 ). 4.(optional) To imp ort transp ort property da ta, enable Imp ort da tabase under Transp ort Property Data (Optional) and sp ecify the lo cation of the sp ecies tr ansp ort property da ta.You c an include the da ta in the k inetics input file and/or in a separ ate file as f ollows: •If you w ant to sp ecify tr ansp ort property da ta for all sp ecies in the k inetics input file , enable All con- tained in K inetics Input F ile, to avoid the need t o sp ecify a separ ate file . •If you w ant to pr ovide some or all sp ecies tr ansp ort da ta in a separ ate file , disable All contained in Kinetics Input F ile and sp ecify the tr ansp ort property da ta file lo cation. ANSY S Fluen t will enable mix ture-averaged multic omp onen t diffusion and set the L ennar d-Jones kinetic theor y par amet ers f or all the sp ecies in the imp orted CHEMKIN mechanism. If you w ould like to use S tefan-M axwell diffusion, enable the Full M ultic omp onen t Diffusion in the Species dialo g box. Onc e the CHEMKIN files ar e imp orted, ANSY S Fluen t creates a ma terial with the sp ecified name , which will c ontain the da ta for the sp ecies and r eactions , and add it t o the list of a vailable Mixture Materials in the Create/Edit M aterials D ialog Box (p.3386 ).The metho ds t o comput e the mix ture's material pr operties ar e set aut oma tically dep ending on which chemistr y solv er y ou selec ted. For c ases with imp orted tr ansp ort property da ta, the metho ds used t o calcula te pr operties ar e shown in the table b elow. CHEMKIN-CFD S olver Stiff C hemistr y Solver Material P roperty chemk in [a] mixing la w Specific H eat chemk in [a] ideal-gas-mixing-la w Visc osit y chemk in [a] ideal-gas-mixing-la w Thermal C onduc tivit y chemk in [a] kinetics-theor y Mass D iffusivit y chemk in [a] kinetics-theor y Thermal D iffusion a.The ma terial pr operty value will b e comput ed b y ANSY S Chemk in-P ro.You ma y cho ose to use a diff erent property metho d if it is mor e suitable f or y our pr oblem. For c ases with the CHEMKIN-CFD S olver tha t do not use tr ansp ort property da ta, only the Spe- cific H eat mix ture pr operty will b e aut oma tically set t o the chemk in metho d. 1627Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Volumetr ic ReactionsNote tha t when Full M ultic omp onen t Diffusion is enabled in the Species dialo g box, ANSY S Chemk in-P ro retur ns full multic omp onen t diffusivities . If Full M ultic omp onen t Diffusion is disabled , ANSY S Chemk in-P ro retur ns mix ture averaged mass diffusivities f or each sp ecies . Figur e 15.6: The M aterial D ialo g Box When Imp orting CHEMKIN Transp ort Properties 5.Click the Imp ort butt on. Onc e you click Imp ort, ANSY S Fluen t aut oma tically sa ves the r eaction mechanism and ther mal files in the da ta str ucture.The or iginal input files ar e not r equir ed t o be retained along with the Fluen t case file . ANSY S Fluen t will aut oma tically r egener ate these files as needed (f or e xample , when using the CHEMKIN-CFD solv er). For inf ormation on ho w to imp ort a sur face kinetic mechanism in CHEMKIN f ormat, see Imp orting a Surface Kinetic M echanism in CHEMKIN F ormat (p.1655 ). 15.1.3.3. CHEMKIN Mechanisms Included with ANSY S Fluent A CHEMKIN mechanism is a chemic al reaction mechanism (also c alled a chemistr y set) tha t has the following mechanism c omp onen ts: •A file c ontaining ther mochemic al da ta for the chemic al sp ecies of in terest •A file c ontaining a descr iption of the r eactions o ccur ring in the gas phase •(Optional) A file c ontaining a descr iption of the r eactions o ccur ring a t the gas-sur face interface or on the surface •(Optional) A file c ontaining gas-phase tr ansp ort da ta Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1628Modeling S pecies Transp ort and F inite-Rate Chemistr yA set of gas-phase and/or sur face reactions ar e gener ally de velop ed using sp ecific ther mochemic al data.Thus, the gas-phase k inetics , sur face kinetics , and ther modynamic da ta ar e treated as a chemistr y “set” in r eacting-flo w simula tions . ANSY S Fluen t provides the f ollowing fuel-c ombustion mechanisms (including r eactions , ther modynamic da ta, and tr ansp ort da ta) tha t are appr opriate for use in c ommon combustion simula tions: •Methane / E thane: 50-sp ecies v ersion of GRI-M ech 3.0 (grimech30_50spec ) This is the or iginal GRI-mech 3.0 (53 sp ecies) [120] (p.4011 ) with thr ee sp ecies (ar gon AR, propane C3H8, and pr opyl radic al C3H7) and their r eactions r emo ved. In fuel/air or fuel/o xygen c ombustion, the r emo val of these sp ecies is e xpected t o ha ve negligible effect on the mechanism pr edic tive capabilities f or methane and ethane as fuels .The applic abilit y of the GRI mechanism and v alida tion c ases ar e pr ovided on the GRI mechanism w eb sit e [120] (p.4011 ). •Propane: 37-sp ecies high-t emp erature mechanism ( Propane-NOx_highT ) The mechanism has 211 elemen tary reaction st eps and w as obtained b y remo ving sp ecies and r e- actions tha t are unimp ortant for pr opane c ombustion fr om the c ompr ehensiv e mast er mechanism [81] (p.4009 ). ANSY S Chemk in-P ro Reaction Workbench sof tware was used t o reduc e the mast er mechanism under the c onditions of sligh tly lean and high pr essur e laminar flame of a pr opane/air mixture using the D irected R elation G raph (DR G) metho d. •Two hydrogen mechanisms: –9-sp ecies v ersion f or H2 c ombustion ( H2_mech ) The mechanism has 21 elemen tary reaction st eps and has b een e xtracted fr om the Li et al. [65] (p.4008 ) mechanism f or C O and other h ydrocarbons. –21-sp ecies v ersion f or H2 c ombustion with NO x (H2_NOx_mech ) The mechanism has 105 elemen tary reaction st eps.The h ydrogen c ombustion sub-mechanism is the same as the H2_mech mechanism, above.The NOx sub-mechanism is based on the stud y by the G larb org gr oup [99] (p.4010 ). 15.1.4. Defining P roperties f or the M ixture and I ts C onstituen t Species As discussed in Overview of U ser Inputs f or M odeling S pecies Transp ort and R eactions (p.1614 ), if y ou use a mix ture ma terial fr om the ANSY S Fluen t da tabase , most mix ture and sp ecies pr operties will already be defined .You ma y follow the pr ocedur es in this sec tion t o check the cur rent properties, modify some of the pr operties, or set all pr operties f or a br and-new mix ture ma terial tha t you ar e de- fining fr om nothing . Rememb er tha t you will need t o define pr operties f or the mix ture ma terial and also f or its c onstituen t species . It is imp ortant tha t you define the mix ture pr operties b efore setting an y pr operties f or the constituen t sp ecies , sinc e the sp ecies pr operty inputs ma y dep end on the metho ds y ou use t o define the pr operties of the mix ture. The r ecommended sequenc e for pr operty inputs is as f ollows: 1.Define the mix ture sp ecies , and r eaction(s), and define ph ysical pr operties f or the mix ture. Rememb er to click the Change/C reate butt on when y ou ar e done setting pr operties f or the mix ture ma terial. 1629Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Volumetr ic Reactions2.Define ph ysical pr operties f or the sp ecies in the mix ture. Rememb er to click the Change/C reate butt on after defining the pr operties f or each sp ecies . These st eps, all of which ar e performed in the Create/Edit M aterials D ialog Box (p.3386 ), are descr ibed in detail in this sec tion. Setup → Materials 15.1.4.1. Defining the Sp ecies in the M ixture In the Create/Edit M aterials dialo g box (Figur e 15.7: The C reate/Edit M aterials D ialog Box (Showing a M ixture M aterial) (p.1630 )), check tha t the Material Type is set t o mix ture and y our mix ture is selec ted in the Fluen t Mixture M aterials list. Figur e 15.7: The C reate/Edit M aterials D ialo g Box (S howing a M ixture M aterial) Click the Edit... butt on t o the r ight of Mixture Species under the Properties group b ox and in the Species D ialog Box (p.3417 ) (Figur e 15.8: The S pecies D ialog Box (p.1631 )) tha t op ens define the sp ecies in the mix ture ma terial. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1630Modeling S pecies Transp ort and F inite-Rate Chemistr yFigur e 15.8: The S pecies D ialo g Box Imp ortant For C hemk in mechanisms , the r ecommended appr oach f or mo difying mix ture ma terials is to mo dify the C hemk in mechanism file and then r e-imp ort it in to your F luen t case. 15.1.4.1.1. Overview of the Sp ecies D ialo g Box In the Species dialo g box, the Selec ted S pecies list sho ws all of the fluid-phase sp ecies in the mix ture. If you ar e mo deling w all or par ticle sur face reactions , the Selec ted S olid S pecies list will sho w all of the bulk solid sp ecies in the mix ture. Solid sp ecies ar e sp ecies tha t are dep osit t o, or et ch fr om, wall b oundar ies or discr ete-phase par ticles (f or e xample , Si(s)) and do not e xist as fluid-phase sp ecies . If you ar e mo deling w all sur face reactions with sit e balancing , wher e sp ecies adsorb on to the w all surface, react, and then desorb off the sur face, the Selec ted S ite Species list will sho w all of the site sp ecies in the mix ture. The use of solid and sit e sp ecies with w all sur face reactions is descr ibed in Wall Sur face Reactions and C hemic al Vapor D eposition (p.1654 ). See Particle Sur face Reactions (p.1661 ) for inf ormation ab out particle sur face reactions . Imp ortant The or der of the sp ecies in the Selec ted S pecies list is v ery imp ortant. ANSY S Fluen t con- siders the last sp ecies in the list t o be the bulk sp ecies .You should ther efore be careful 1631Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Volumetr ic Reactionsto retain the most abundan t sp ecies (b y mass) as the last sp ecies when y ou add sp ecies to or delet e sp ecies fr om a mix ture ma terial. The Available M aterials list sho ws ma terials tha t are available but not in the mix ture. Gener ally, you will see air in this list , sinc e air is alw ays available b y default. 15.1.4.1.2. Adding Sp ecies t o the M ixture If you ar e creating a mix ture from nothing or star ting fr om an e xisting mix ture and adding some missing sp ecies , you will first need t o load the desir ed sp ecies fr om the da tabase (or cr eate them, if the y are not pr esen t in the da tabase) so tha t the y will b e available t o the solv er.You will need t o close the Species dialo g box before you b egin, sinc e it is a “modal” dialo g box tha t will not allo w you t o do an ything else when it is op en.The pr ocedur e for adding sp ecies is as f ollows: 1.In the Create/Edit M aterials dialo g box, click the Fluen t Database ... butt on t o op en the Fluen t Database M aterials dialo g box and c opy the desir ed sp ecies , as descr ibed in Copying M aterials fr om the ANSY S Fluen t Database (p.1084 ). Rememb er tha t the c onstituen t species of the mix ture are fluid materials, so y ou should selec t fluid as the Material Type in the Fluen t Database M aterials dialo g box to see the c orrect list of choic es. Note tha t available solid and sit e sp ecies (f or sur face reactions) are also c ontained in the fluid list. Imp ortant If you do not see the sp ecies y ou ar e lo oking f or in the da tabase , you c an cr eate a new fluid ma terial for tha t sp ecies , following the instr uctions in Creating a N ew M ater- ial (p.1086 ), and then c ontinue with st ep 2, below. 2.Re-op en the Species dialo g box.You will see tha t the fluid ma terials y ou c opied fr om the da tabase (or created) ar e list ed in the Available M aterials list. 3.To add a sp ecies t o the mix ture, selec t it in the Available M aterials list and click the Add butt on b elow the Selec ted S pecies list (or b elow the Selec ted S ite Species or Selec ted S olid S pecies list, to define a sit e or solid sp ecies). The sp ecies will b e added t o the end of the r elevant list and r emo ved fr om the Available M aterials list. 4.Repeat the pr evious st ep f or all the desir ed sp ecies .When y ou ar e finished , click the OK butt on. Imp ortant Adding a sp ecies t o the list will alt er the or der of the sp ecies .You should b e sur e tha t the last sp ecies in the list is the bulk sp ecies , and y ou should check all c ell and b oundar y zone c onditions , under-r elaxa tion fac tors, and other solution par amet ers tha t you ha ve set, as descr ibed in detail in the f ollowing sec tions . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1632Modeling S pecies Transp ort and F inite-Rate Chemistr y15.1.4.1.3. Remo ving Sp ecies fr om the M ixture To remo ve a sp ecies fr om the mix ture, simply selec t it in the Selec ted S pecies list (or the Selec ted Site Species or Selec ted S olid S pecies list) and click the Remo ve butt on b elow the list. The sp ecies will b e remo ved fr om the list and added t o the Available M aterials list. Imp ortant •Remo ving a sp ecies fr om the list will alt er the or der of the sp ecies .You should b e sur e tha t the last sp ecies in the list is the bulk sp ecies , and y ou should check an y cell z one or b oundar y conditions , under-r elaxa tion fac tors, or other solution par amet ers tha t you ha ve set , as de- scribed in detail in the f ollowing sec tions . •Any sp ecies tha t is a r eactant, produc t, or enhanc ed thir d-body in an ac tive reaction c annot be delet ed fr om the mix ture ma terial. 15.1.4.1.4. Assigning the L ast Sp ecies If you find tha t the last sp ecies in the Selec ted S pecies list is not the most abundan t sp ecies (as it should b e), you will need t o rearrange the sp ecies t o obtain the pr oper or der. 1.Selec t the bulk sp ecies in the Selec ted S pecies list. 2.Click Last S pecies .The selec ted sp ecies will b e plac ed a t the end of the Selec ted S pecies list. The transp ort equa tion of the last sp ecies will not b e solv ed. 15.1.4.1.5. The N aming and O rdering of Sp ecies As discussed pr eviously , you should r etain the most abundan t sp ecies as the last one in the Selec ted Species list when y ou add or r emo ve sp ecies . Additional c onsider ations y ou should b e aware of when adding and deleting sp ecies ar e pr esen ted her e. There ar e thr ee char acteristics of a sp ecies tha t iden tify it t o the solv er: name , chemic al formula, and position in the list of sp ecies in the Species dialo g box. Changing these char acteristics will ha ve the following eff ects: •You c an change the Name of a sp ecies (using the Create/Edit M aterials D ialog Box (p.3386 ), as descr ibed in Renaming an Existing M aterial (p.1084 )) without an y consequenc es. •You should never change the giv en Chemic al F ormula of a sp ecies . •You will change the or der of the sp ecies list if y ou add or r emo ve an y sp ecies .When this o ccurs , all c ell zone or b oundar y conditions , solv er par amet ers, and solution da ta for sp ecies will b e reset t o the default values . (Solution da ta, cell z one or b oundar y conditions , and solv er par amet ers f or other flo w variables will not b e aff ected.) Therefore, if you add or r emo ve sp ecies y ou should tak e care to redefine sp ecies cell z one and b oundar y conditions and solution par amet ers f or the newly defined pr oblem. In addition, you should r ecogniz e tha t pa tched sp ecies c oncentrations or c oncentrations st ored in an y da ta file tha t was based on the or iginal sp ecies or dering will b e inc ompa tible with the newly defined pr oblem. You can use the da ta file as a star ting guess , but y ou should b e aware tha t the sp ecies c oncentrations in the data file ma y pr ovide a p oor initial guess f or the newly defined mo del. 1633Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Volumetr ic Reactions15.1.4.2. Defining R eac tions If your ANSY S Fluen t mo del in volves chemic al reactions , you c an define the r eactions in which the defined sp ecies par ticipa te.This will b e nec essar y only if y ou ar e creating a mix ture ma terial fr om nothing , you ha ve mo dified the sp ecies , or y ou w ant to redefine the r eactions f or some other r eason. Depending on which turbulenc e-chemistr y interaction mo del y ou selec ted in the Species M odel dialo g box (see Enabling S pecies Transp ort and R eactions and C hoosing the M ixture M aterial (p.1616 )), the appr opriate reaction mo del will b e displa yed in the Reac tion drop-do wn list in the Edit M aterial dialo g box. If you ar e using the Finit e-Rate/N o TCI or Eddy-D issipa tion C onc ept mo del, the r eaction model will b e finit e-rate; if y ou ar e using the Eddy-D issipa tion mo del, the r eaction mo del will b e edd y-dissipa tion ; if y ou ar e using the Finit e-Rate/Eddy-D issipa tion mo del, the r eaction mo del will be finit e-rate/edd y-dissipa tion . 15.1.4.2.1. Inputs for R eac tion D efinition To define the r eactions , click the Edit... butt on t o the r ight of Reac tion .The Reac tions dialo g box (Figur e 15.9: The R eactions D ialog Box (p.1635 )) will op en. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1634Modeling S pecies Transp ort and F inite-Rate Chemistr yFigur e 15.9: The Reac tions D ialo g Box The st eps f or defining r eactions ar e as f ollows: 1.Set the t otal numb er of r eactions (v olumetr ic reactions , wall sur face reactions , and par ticle sur face re- actions) in the Total N umb er of Reac tions field . Use the ar rows to change the v alue , or t ype in the value and pr ess Enter. Note tha t if y our mo del includes discr ete-phase c ombusting par ticles , you should include the particula te sur face reaction(s) (f or e xample , char bur nout , multiple char o xida tion) in the numb er of reactions only if y ou plan t o use the multiple sur face reactions mo del f or sur face combustion. 2.Specify the Reac tion N ame of the r eaction y ou w ant to define . 3.Set the ID of the r eaction y ou w ant to define . Again, if you t ype in the v alue b e sur e to pr ess Enter. 4.If this is a fluid-phase r eaction, keep the default selec tion of Volumetr ic as the Reac tion Type. If this is a w all sur face reaction (descr ibed in Wall Sur face Reactions and C hemic al Vapor D eposition (p.1654 )) 1635Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Volumetr ic Reactionsor a par ticle sur face reaction (descr ibed in Particle Sur face Reactions (p.1661 )), selec t Wall S urface or Particle S urface as the Reac tion Type. See User Inputs f or P article Sur face Reactions (p.1661 ) for fur ther information ab out defining par ticle sur face reactions . 5.Specify ho w man y reactants and pr oduc ts ar e involved in the r eaction b y incr easing the v alue of the Numb er of Reac tants and the Numb er of P roduc ts. Selec t each r eactant or pr oduc t in the Species drop-do wn list and then set its st oichiometr ic coefficien t and r ate exponen t in the appr opriate Stoi- ch. Coefficien t and Rate Exponen t fields .The st oichiometr ic coefficien t is the c onstan t or in Equa tion 7.6 in the Theor y Guide and the r ate exponen t is the e xponen t on the r eactant or pr oduc t concentration, or in Equa tion 7.7 in the Theor y Guide . There ar e two gener al classes of r eactions tha t can b e handled b y the Reac tions dialo g box, so it is imp ortant tha t the par amet ers f or each r eaction ar e en tered c orrectly.The classes of r eactions are as f ollows: •Global f orward reaction (no r everse r eaction): Produc t species gener ally do not aff ect the f orward rate, so the r ate exponen t for all pr oduc ts ( ) should b e 0. For reactant species , set the r ate exponen t ( ) to the desir ed v alue . If such a r eaction is not an elemen tary reaction, the r ate exponen t will gener ally not b e equal t o the st oichiometr ic coefficien t ( ) for tha t species . An example of a global forward reaction is the c ombustion of methane: (15.1) wher e , , , , , , , and . Figur e 15.9: The R eactions D ialog Box (p.1635 ) sho ws the c oefficien t inputs f or the c ombustion of methane . See also the methane-air mix ture ma terial in the Fluen t Database M aterials D ialog Box (p.3396 ). Note tha t, in c ertain c ases , you ma y want to mo del a r eaction wher e pr oduc t sp ecies aff ect the f orward rate. For such c ases , set the pr oduc t rate exponen t ( ) to the desir ed v alue . An example of such a r eaction is the gas-shif t reaction (see the carb on-mono xide-air mix ture material in the Fluen t Database M aterials D ialog Box (p.3396 )), in which the pr esenc e of w ater has an eff ect on the r eaction r ate: In the gas-shif t reaction, the r ate expression ma y be defined as: (15.2) wher e , , , , , , , and . •Reversible r eaction: An elemen tary chemic al reaction tha t assumes the r ate exponen t for each sp ecies is equiv alen t to the st oichiometr ic coefficien t for tha t species . An example of an elemen tary reaction is the o xida tion of SO2 to SO3: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1636Modeling S pecies Transp ort and F inite-Rate Chemistr ywher e , , , , , and . See st ep 7 b elow for inf ormation ab out ho w to enable r eversible r eactions . 6.If you ar e using the laminar finit e-rate, finit e-rate/edd y-dissipa tion, edd y-dissipa tion c oncept or PDF transp ort mo del f or the turbulenc e-chemistr y interaction, enter the f ollowing par amet ers f or the Arrhenius r ate in the Arrhenius R ate group b ox: Note All quan tities f or the A rrhenius r ate par amet ers ar e in units of k gmol, m3, and sec onds . Pre-Exponen tial F actor (the c onstan t in Equa tion 7.9 in the Theor y Guide ).The units of must b e sp ecified such tha t the units of the molar r eaction r ate, in Equa tion 7.5 in the Theor y Guide , are moles/v olume-time (for e xample , kmol/ -s) and the units of the v olumetr ic reaction r ate, in Equa tion 7.5 in the Theor y Guide , are mass/v olume-time (f or e xample , kg/ -s). Imp ortant It is imp ortant to not e tha t if y ou ha ve selec ted the B ritish units sy stem, the Arrhenius fac tor should still b e en tered in SI units .This is b ecause ANSY S Fluen t applies no c onversion fac tor to your input of (the c onversion fac tor is 1.0) when you w ork in B ritish units , as the c orrect conversion fac tor dep ends on y our inputs for , , and so on. Activation E nergy (the c onstan t in the f orward rate constan t expression, Equa tion 7.9 in the Theor y Guide ). Temp erature Exponen t (the v alue f or the c onstan t in Equa tion 7.9 in the Theor y Guide ). Third-B ody Efficiencies (the v alues f or in Equa tion 7.8 in the Theor y Guide ). If you ha ve accur ate da ta for the efficiencies and w ant to include this eff ect on the r eaction r ate (tha t is, include in Equa tion 7.7 in the Theor y Guide ), selec t the Third Body Efficiencies option and click the Specify ... butt on t o op en the Third- Body Efficienc y Dialog Box (p.3423 ) (Figur e 15.10: The Third-Body Efficienc y Dialog Box (p.1638 )). For each Species in the dialo g box, specify the Third-B ody Efficienc y. Imp ortant It is not nec essar y to include the thir d-body efficiencies .You should not enable the Third-B ody Efficiencies option unless y ou ha ve accur ate da ta for these paramet ers. 1637Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Volumetr ic ReactionsFigur e 15.10: The Third-B ody Efficienc y D ialo g Box Pressur e-D ependen t Reac tion (if relevant) If you ar e using the laminar finit e-rate or edd y-dissipa tion c oncept mo del f or turbulenc e- chemistr y interaction, or ha ve selec ted the c omp osition PDF tr ansp ort mo del (see Modeling a Comp osition PDF Transp ort Problem (p.1779 )), and the r eaction is a pr essur e fall-off r eaction (see Pressur e-Dependen t Reactions in the Theor y Guide ), enable the Pressur e-D ependen t Reac tion option f or the Arrhenius R ate and click the Specify ... butt on t o op en the Pressur e-D ependen t Reac tion dialo g box (Figur e 15.11: The P ressur e-Dependen t Reaction D ialog Box (p.1639 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1638Modeling S pecies Transp ort and F inite-Rate Chemistr yFigur e 15.11: The P ressur e-D ependen t Reac tion D ialo g Box Under Reac tion P aramet ers, selec t the appr opriate Reac tion Type (lindemann ,troe, or sri). See Pressur e-Dependen t Reactions in the Theor y Guide for details ab out the thr ee metho ds. Next, specify if the Bath G as C onc entration ( in Equa tion 7.18 in the Theor y Guide ) is t o be defined as the c oncentration of the mix ture, or as the c oncentration of one of the mix ture’s constituen t sp ecies , by selec ting the appr opriate item in the dr op-do wn list. Enabling the Chemic ally A ctivated Bimolecular Reac tion option r esults in a net r ate constan t at an y pr essur e being defined as Equa tion 7.24 in the Theor y Guide . The par amet ers y ou sp ecified under Arrhenius R ate in the Reac tions dialo g box represen t the high-pr essur e Arrhenius par amet ers.You c an, however, specify v alues f or the f ollowing paramet ers under Low P ressur e Arrhenius R ate: ln(P re-Exponen tial F actor) ( in Equa tion 7.16 in the Theor y Guide ) The pr e-exponen tial fac tor is of ten an e xtremely large numb er, so y ou will input the na tural lo garithm of this t erm. Activation E nergy ( in Equa tion 7.16 in the Theor y Guide ) Temp erature Exponen t ( in Equa tion 7.16 in the Theor y Guide ) 1639Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Volumetr ic ReactionsIf you selec ted troe for the Reac tion Type, you c an sp ecify v alues f or Alpha ,T1,T2, and T3 ( , , , and in Equa tion 7.21 in the Theor y Guide ) under Troe par amet ers. If you selec ted sri for the Reac tion Type, you c an sp ecify v alues f or a,b,c,d, and e ( , , , , and in Equa tion 7.22 in the Theor y Guide ) under SRI par amet ers. Coverage D ependen t Reac tion If you ar e mo deling Wall S urface reactions with sit e-balancing and y ou ha ve reaction r ates tha t dep end on sit e coverages , you c an enable the Coverage D ependen t Reac tion option. Click Specify ... to op en the Coverage D ependen t Reac tion dialo g box (Figur e 15.12: The C overage D ependen t Reaction D ialog Box (p.1640 )) and input the c overage par amet ers. Figur e 15.12: The C overage D ependen t Reac tion D ialo g Box In the Coverage D ependen t Reac tion dialo g box, all the sit e sp ecies of the r eaction will b e presen t with a default v alue of 0 f or all the par amet ers, corresponding t o no sur face coverage modific ation. Enter the r elevant values of the par amet ers , , and (as defined in Equa- tion 7.52 in the Theor y Guide ) for all the sp ecies f or which the r eaction has c overage dep end- ence. and are dimensionless , and is in units of J/k gmol. 7.If you ar e using the laminar finit e-rate, edd y-dissipa tion c oncept or PDF tr ansp ort mo del f or turbulenc e- chemistr y interaction, and the r eaction is r eversible , enable the Include B ack ward Reac tion option f or the Arrhenius R ate.When this option is enabled , you will not b e able t o edit the Rate Exponen t for the pr oduc t species , which inst ead will b e set t o be equiv alen t to the c orresponding pr oduc t Stoi- ch. Coefficien t. By default , ANSY S Fluen t calcula tes the r everse r eaction r ate constan ts using Equa- tion 7.10 in the Fluent Theor y Guide .You c an o verwrite the ANSY S Fluen t’s default par amet ers f or the reactions or define y our o wn r eactions . In b oth sc enar ios, you also need t o sp ecify the standar d-sta te enthalp y and standar d-sta te en tropy for mix ture ma terial. ANSY S Fluen t will use these v alues in the calcula tion of the back ward reaction r ate constan t (Equa tion 7.10 in the Fluent Theor y Guide ). In addition, you ha ve the option t o pr ovide y our o wn back ward reaction par amet ers.To do this , click Specify ... next to Include B ack ward Reac tion and enable the Arrhenius B ack ward Rate option in the Back ward Reac tion P aramet ers dialo g box tha t op ens (see Figur e 15.13: Backward Reaction P aramet ers D ialog Box (p.1641 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1640Modeling S pecies Transp ort and F inite-Rate Chemistr yFigur e 15.13: Back ward Reac tion P aramet ers D ialo g Box You c an sp ecify the f ollowing back ward rate par amet ers: Pre-Exponen tial F actor (the c onstan t in Equa tion 7.14 in the Fluent Theor y Guide ). Activation E nergy (the c onstan t in the back ward rate constan t expression in Equa tion 7.14 in the Fluent Theor y Guide ). Temp erature Exponen t (the c onstan t in Equa tion 7.14 in the Fluent Theor y Guide ). ANSY S Fluen t will use y our cust om v alues t o calcula te the back ward rate constan t of the r eversible reaction acc ording t o Equa tion 7.14 in the Fluent Theor y Guide . Note tha t the r eversible r eaction option is not a vailable f or either the edd y-dissipa tion or the finit e- rate/edd y-dissipa tion turbulenc e-chemistr y interaction mo del. 8.If you ar e using the edd y-dissipa tion or finit e-rate/edd y-dissipa tion mo del f or turbulenc e-chemistr y interaction, you c an en ter values f or A and B under the Mixing R ate heading .These v alues should not be changed unless y ou ha ve reliable da ta. In most c ases y ou will use the default v alues . A is the c onstan t in the turbulen t mixing r ate (Equa tion 7.25 and Equa tion 7.26 in the Theor y Guide ) when it is applied t o a sp ecies tha t app ears as a r eactant in this r eaction. The default setting of 4.0 is based on the empir ically der ived v alues giv en b y Magnussen et al. [72] (p.4009 ). B is the c onstan t in the turbulen t mixing r ate (Equa tion 7.26 in the Theor y Guide ) when it is applied t o a sp ecies tha t app ears as a pr oduc t in this r eaction. The default setting of 0.5 is based on the empir ically der ived v alues giv en b y Magnussen et al. [72] (p.4009 ). 9.Repeat steps 2–8 f or each r eaction y ou need t o define . After defining all r eactions , click OK. 15.1.4.2.2. Defining Sp ecies and R eac tions for F uel M ixtures Quite of ten, combustion sy stems will include fuel tha t is not easily descr ibed as a pur e sp ecies (such as CH4 or C2H6). Comple x hydrocarbons, including fuel oil or e ven w ood chips , ma y be difficult t o define in t erms of such pur e sp ecies . However, if y ou ha ve available the hea ting v alue and the ultima te analy sis (elemen tal c omp osition) of the fuel, you c an define an equiv alen t fuel sp ecies and an equi- valen t hea t of f ormation f or this fuel. Consider , for e xample , a fuel k nown t o contain 50% C, 6% H, 1641Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Volumetr ic Reactionsand 44% O b y weigh t. Dividing b y atomic w eigh ts, you c an ar rive at a “fuel” species with the mo- lecular f ormula C4.17H6O275.You c an star t from a similar , existing sp ecies or cr eate a sp ecies fr om nothing , and assign it a molecular w eigh t of 100.04 k g/kmol (4.17 12 + 6 1 + 2.75 16). The chemic al reaction w ould b e consider ed t o be (15.3) You will need t o set the appr opriate stoichiometr ic coefficien ts for this r eaction. The hea t of f ormation (or standar d-sta te en thalp y) for the fuel sp ecies c an b e calcula ted fr om the known hea ting v alue sinc e (15.4) wher e is the standar d-sta te en thalp y on a molar basis . Note the sign c onvention in Equa- tion 15.4 (p.1642 ) : is nega tive when the r eaction is e xother mic. 15.1.4.3. Defining Z one-B ased R eac tion Mechanisms If your ANSY S Fluen t mo del in volves reactions tha t are confined t o a sp ecific ar ea of the domain, you can define “reaction mechanisms ” to enable diff erent reactions selec tively in diff erent geometr ical zones .You c an cr eate reaction mechanisms b y selec ting r eactions fr om those defined in the Reac tions dialo g box and gr ouping them. You c an then assign a par ticular mechanism t o a par ticular z one . 15.1.4.3.1. Inputs for R eac tion Mechanism D efinition To define a r eaction mechanism, click the Edit... butt on t o the r ight of Mechanism .The Reaction Mechanisms D ialog Box (p.3428 ) (Figur e 15.14: The R eaction M echanisms D ialog Box (p.1642 )) will op en. Figur e 15.14: The Reac tion M echanisms D ialo g Box Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1642Modeling S pecies Transp ort and F inite-Rate Chemistr yThe st eps f or defining a r eaction mechanism ar e as f ollows: 1.Set the t otal numb er of mechanisms in the Numb er of M echanisms field . Use the ar rows to change the v alue , or t ype the v alue and pr ess Enter. 2.Set the Mechanism ID of the mechanism y ou w ant to define . Again, if you t ype in the v alue , be sur e to pr ess Enter. 3.Specify the Name of the mechanism. 4.Selec t the t ype of r eaction t o add t o the mechanism under Reac tion Type. If you selec t Volumetr ic, the Reac tions list will displa y all a vailable fluid-phase r eactions . If you selec t Wall S urface or Particle Surface, the Reac tions list will displa y all a vailable w all sur face reactions (descr ibed in Wall Sur face Reactions and C hemic al Vapor D eposition (p.1654 )) or par ticle sur face reactions (descr ibed in Particle Surface Reactions (p.1661 )). If you selec t All, the Reac tions list will displa y all a vailable r eactions .This option is mean t for back ward compa tibilit y with ANSY S Fluen t 6.0 or ear lier c ases . 5.Selec t the r eactions t o be included in the mechanism. •For Volumetr ic or Particle S urface reactions , selec t available r eactions f or the mechanism in the Reac tions list. •For Wall S urface reactions , use the f ollowing pr ocedur e: a.Selec t available w all sur face reactions f or the mechanism in the Reac tions list. b.If any sit e sp ecies app ear in the selec ted r eaction(s), set the numb er of sit es in the Numb er of Sites field . Use the ar rows to change the v alue , or t ype the v alue and pr ess Enter. See Reaction- Diffusion B alanc e for Sur face Chemistr y in the Theor y Guide f or details ab out sit e sp ecies in w all surface reactions . c.If you sp ecify a Numb er of S ites tha t is gr eater than z ero, specify the pr operties of the sit e. Site Name (optional) Site Densit y (in k mol/m2) This v alue is t ypic ally in the r ange of 10-8 to 10-6. Click the Define ... butt on.This will op en the Site Paramet ers D ialog Box (p.3430 ) (Fig- ure 15.15: The S ite Paramet ers D ialog Box (p.1644 )), wher e you will define the par amet ers of the sit e sp ecies . 1643Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Volumetr ic ReactionsFigur e 15.15: The S ite Paramet ers D ialo g Box Site Name is the optional name of the sit e tha t was sp ecified in the Reac tion M echanisms dialo g box. Total N umb er of S ite Species is the numb er of adsorb ed sp ecies tha t are to be mo deled a t the sit e. (Use the ar rows to change the v alue , or t ype the v alue and pr ess Enter.) Under Site Species , selec t the appr opriate sp ecies fr om the dr op-do wn list(s) and specify the fr actional Initial S ite Coverage for each sp ecies . For st eady-sta te calcula tions , it is r ecommended (though not str ictly r equir ed) tha t the initial v alues of Initial S ite Coverage sum t o unit y. For tr ansien t calcula tions , it is r equir ed tha t these v alues sum to unit y. Click Apply in the Site Paramet ers dialo g box to store the new v alues . 6.Repeat steps 2–5 f or each r eaction mechanism y ou need t o define .When y ou ar e finished defining all reaction mechanisms , click OK. 15.1.4.4. Defining P hysical P roperties for the M ixture When y our ANSY S Fluen t mo del includes chemic al sp ecies , the f ollowing ph ysical pr operties must be defined , either b y you or b y the da tabase , for the mix ture ma terial: •densit y, which y ou c an define using the gas la w or as a v olume-w eigh ted func tion of c omp osition •viscosity, which y ou c an define as a func tion of c omp osition •ther mal c onduc tivit y and sp ecific hea t (in pr oblems in volving solution of the ener gy equa tion), which you c an define as func tions of c omp osition •mass diffusion c oefficien ts and Schmidt numb er, which go vern the mass diffusion flux es (Equa tion 7.2 and Equa tion 7.3 in the Theor y Guide ) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1644Modeling S pecies Transp ort and F inite-Rate Chemistr yDetailed descr iptions of these pr operty inputs ar e pr ovided in Physical Properties (p.1079 ). Imp ortant Rememb er to click the Change/C reate butt on when y ou ar e done setting the pr operties of the mix ture ma terial.The pr operties tha t app ear f or each of the c onstituen t sp ecies will dep end on y our settings f or the pr operties of the mix ture ma terial. If, for e xample , you specify a c omp osition-dep enden t visc osity for the mix ture, you will need t o define visc osity for each sp ecies . 15.1.4.5. Defining P hysical P roperties for the Sp ecies in the M ixture For each of the fluid ma terials in the mix ture, you (or the da tabase) must define the f ollowing ph ys- ical pr operties: •molecular w eigh t, which is used in the gas la w and/or in the c alcula tion of r eaction r ates and mole-fr action inputs or outputs •standar d-sta te (formation) en thalp y and r eference temp erature (in pr oblems in volving solution of the ener gy equa tion) •viscosity, if you defined the visc osity of the mix ture ma terial as a func tion of c omp osition •ther mal c onduc tivit y and sp ecific hea t (in pr oblems in volving solution of the ener gy equa tion), if you defined these pr operties of the mix ture ma terial as func tions of c omp osition •standar d-sta te en tropy, if you ar e mo deling r eversible r eactions •ther mal and momen tum acc ommo dation c oefficien ts, if you ha ve enabled the lo w-pr essur e boundar y slip mo del. Detailed descr iptions of these pr operty inputs ar e pr ovided in Physical Properties (p.1079 ). Imp ortant Global r eaction mechanisms with one or t wo steps ine vitably neglec t the in termedia te species . In high-t emp erature flames , neglec ting these disso ciated sp ecies ma y cause the temp erature to be overpredic ted. A mor e realistic t emp erature field c an b e obtained b y increasing the sp ecific hea t capacit y for each sp ecies . Rose and C ooper [102] (p.4010 ) have created a set of sp ecific hea t polynomials as a func tion of t emp erature. The sp ecific hea t capacit y for each sp ecies is c alcula ted as (15.5) 1645Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Volumetr ic ReactionsThe mo dified polynomial c oefficien ts (J/kg-K) ar e pr ovided in Table 15.1: Modified S pe- cific H eat Capacit y (Cp) P olynomial C oefficien ts (p.1646 ). Table 15.1: Modified S pecific H eat Capacit y (Cp) P olynomial C oefficien ts Coefficien t 8.76317e+02 1.93780e+03 5.35446e+02 1.22828e-01 -1.18077e+00 1.27867e+00 5.58304e-04 3.64357e-03 -5.46776e-04 -1.20247e-06 -2.86327e-06 -2.38224e-07 1.14741e-09 7.59578e-10 1.89204e-10 -5.12377e-13 — — 8.56597e-17 — — 15.1.5. Setting up C oal S imula tions with the C oal C alcula tor D ialo g Box The Coal C alcula tor dialo g box aut oma tes c alcula tion and setting of the r elevant input par amet ers for the S pecies , Discrete-Phase (DPM) and P ollutan t mo dels asso ciated with c oal c ombustion. It is available in the Species dialo g box for the Species Transp ort mo del when the Eddy-D issipa tion or Finit e-Rate/Eddy-D issipa tion turbulenc e-chemistr y option is selec ted.You c an define up t o thr ee coal str eams in y our simula tion using the Numb er of C oal S treams entry box. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1646Modeling S pecies Transp ort and F inite-Rate Chemistr yFigur e 15.16: The C oal C alcula tor D ialo g Box For each c oal str eam selec ted in the Coal S tream ID , you need t o define the f ollowing pr operties: 1.Coal Proxima te Analy sis, which is the mass fr action of Volatile, Fixed C arb on, Ash and Moistur e in the coal. ANSY S Fluen t will nor maliz e the mass fr actions so tha t the y sum t o unit y. 1647Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Volumetr ic Reactions2.Coal Ultima te Analy sis, which is the mass fr action of a tomic C, H, O, N and optionally S, in the D ry-Ash- Free (DAF) c oal. ANSY S Fluen t will nor maliz e the mass fr actions so tha t the y sum t o unit y. 3.A choic e of One-st ep or Two-st ep chemic al mechanism. The one-st ep mechanism is , (15.6) The t wo-st ep mechanism in volves o xida tion of v olatiles t o CO in the first r eaction and o xida tion of C O to CO2 in the sec ond r eaction: (15.7) The st oichiometr ic coefficien ts in Equa tion 15.6 (p.1648 ) and Equa tion 15.7 (p.1648 ) are calcula ted from the ultima te and pr oxima te analy ses. 4.An option t o Include SO2 .When this is enabled , an input f or the a tomic mass fr action of sulphur ,S, app ears in the ultima te analy sis fr ame . 5.The Coal P article M aterial N ame . A DPM c ombusting-par ticle ma terial will b e created with this name . The default name is coal-par ticle . 6.The Coal A s-Rec eived HCV , wher e HCV denot es the Higher C alor ific Value . 7.Volatile M olecular Weigh t is the molecular w eigh t of pur e volatiles . 8.The CO/C O2 S plit in Reac tion 1 P roduc ts can b e used t o sp ecify the molar fr action of C O to CO2 in the first r eaction of Equa tion 15.7 (p.1648 ).The default v alue of 1 implies tha t all c arbon is r eacted t o CO, with no C O2 produced. 9.The High Temp erature Volatile Yield . Enhanc ed de volatization a t higher t emp eratures c an c ause the volatile yield t o exceed the pr oxima te analy sis fr action. To mo del this , the ac tual v olatile fr action used is calcula ted as tha t specified in the Proxima te Analy sis input multiplied b y the High Temp erature Volatile Yield .The ac tual fix ed c arbon fr action is then c alcula ted as one minus the sum of the ac tual volatile, ash and moistur e fractions . 10.Fraction of N in C har (DAF) .This input is used in c alcula ting the split of a tomic nitr ogen f or the F uel NOx mo del. 11.Coal D ry Densit y is used t o calcula te the v olume fr action of liquid-w ater for the Wet C ombustion option in the Injec tions dialo g box. Clicking Apply will sa ve the Coal P roperty data for the selec ted Coal S tream ID .When y ou click OK, ANSY S Fluen t mak es the f ollowing changes: 1.A M ixture ma terial is cr eated, named coal-v olatiles-air , with a one or t wo step r eaction mechanism as specified in the Mechanism option. If the Fluid material sp ecies (O2, CO, CO2, and so on) do not e xist, they are created. A Fluid material c alled coal-v olatiles , is also cr eated with a standar d sta te en thalp y cal- cula ted fr om the ultima te and pr oxima te analy ses, as-r eceived HCV and v olatile molecular w eigh t. For the sec ond and thir d coal str eams , additional Fluid materials and r eactions with the pr operties c orres- ponding t o the sec ond and thir d coal str eams ar e also cr eated in the mix ture. 2.A combusting-par ticle ma terial is cr eated f or each c oal str eam with Volatile C omp onen t Fraction and Combustible F raction calcula ted fr om the ultima te and pr oxima te analy ses.The discr ete phase mo del (DPM) is enabled . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1648Modeling S pecies Transp ort and F inite-Rate Chemistr y3.For the fuel NO x mo del, the default fuel sp ecies is set t o vol, the char N c onversion is set t o NO, and the fuel NO x Volatile and Char mass fr actions ar e set acc ording t o the ultima te and pr oxima te comp ositions of the first c oal str eam. Note tha t even though some of the default fuel NO x par amet ers ar e changed , the fuel NO x mo del itself is not enabled . 4.If the Moistur e mass fr action in the c oal pr oxima te analy sis is nonz ero, then the Wet C ombustion option is enabled in the Coal C alcula tor dialo g box, and all subsequen t injec tions tha t are created will ha ve wet combustion enabled .The liquid ma terial will b e set t o water-liquid , and the v olume fr action of w ater will b e calcula ted fr om the Moistur e mass fr action sp ecified in the pr oxima te analy sis and the Coal D ry Densit y.The w et combustion settings ar e not mo dified f or e xisting injec tions .The Densit y for the c om- busting-par ticle in the Create/Edit M aterials dialo g box will also b e set t o Coal D ry Densit y. Note Irrespective of the Wet C ombustion option in the Coal C alcula tor dialo g box you c an modify the Wet C ombustion mo del setting f or the injec tions in the Set Injec tion P roperties dialo g box. In addition, you will need t o tak e care to en ter the flo w-rate of each injec tion on a w et or dr y basis , consist ent with the Wet C ombustion mo del setting . 15.1.6. Defining C ell Z one and B oundar y Conditions f or S pecies You will need t o sp ecify the inlet mass fr action f or all sp ecies in y our simula tion. In addition, for pr essur e outlets y ou will set sp ecies mass fr actions t o be used in c ase of backflo w. At walls, ANSY S Fluen t will apply a z ero-gr adien t (zero-flux) b oundar y condition f or all sp ecies b y default , although y ou c an change each sp ecies b oundar y condition t o a sp ecified v alue . If you ha ve sur face reactions defined (see Wall Surface Reactions and C hemic al Vapor D eposition (p.1654 )), you c an cho ose t o enable w all-sur face reac- tions and selec t the chemic al mechanism. For fluid z ones , you also ha ve the option of sp ecifying a reaction mechanism. Input of c ell z one and b oundar y conditions is descr ibed in Cell Z one and Boundar y Conditions (p.835). Imp ortant •Non-r eflec ting b oundar y conditions (NRBCs) ar e not c ompa tible with sp ecies tr ansp ort mo dels . They are mainly used t o solv e ideal-gas single sp ecies flo w. For inf ormation ab out NRBCs , see Boundar y Acoustic Wave Models (p.1021 ). •Note tha t you will e xplicitly set mass fr actions only f or the first species .The solv er will comput e the mass fr action of the last sp ecies b y subtr acting the t otal of the sp ecified mass fractions fr om 1. If you w ant to explicitly sp ecify the mass fr action of the last sp ecies , you must reorder the sp ecies in the list (in the Create/Edit M aterials D ialog Box (p.3386 )), as descr ibed in Defining P roperties f or the M ixture and I ts Constituen t Species (p.1629 ). 15.1.6.1. Diffusion at Inlets with the P ressur e-B ased S olver For the pr essur e-based solv er in ANSY S Fluen t, the net tr ansp ort of sp ecies a t inlets c onsists of b oth convection and diffusion c omp onen ts.The c onvection c omp onen t is fix ed b y the sp ecified inlet species mass or mole fr action, wher eas the diffusion c omp onen t dep ends on the gr adien t of the comput ed sp ecies c oncentration field (which is not k nown a pr iori). At very small c onvective inlet velocities , for e xample when mo deling p erforated c ombustion liners with an inlet , substan tial mass 1649Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Volumetr ic Reactionscan b e gained or lost thr ough the inlet due t o diffusion. For this r eason, inlet diffusion is disabled b y default , but c an b e enabled with the Inlet D iffusion option in the Species M odel dialo g box. Setup → Models → Species Edit... 15.1.7. Defining O ther S our ces of C hemic al S pecies You c an define a sour ce or sink of a chemic al sp ecies within the c omputa tional domain b y defining a sour ce term in the Fluid dialo g box.You ma y cho ose this appr oach when sp ecies sour ces e xist in y our problem but y ou do not w ant to mo del them thr ough the mechanism of chemic al reactions .Defining Mass, Momen tum, Ener gy, and O ther S ources (p.908) descr ibes the pr ocedur es y ou w ould f ollow to define sp ecies sour ces in y our ANSY S Fluen t mo del. If the sour ce is not a c onstan t, you c an use a user- defined func tion. See the Fluen t Customiza tion M anual for details ab out user-defined func tions . 15.1.8. Solution P rocedur es for C hemic al M ixing and F inite-Rate Chemistr y While man y simula tions in volving chemic al sp ecies ma y requir e no sp ecial pr ocedur es dur ing the solution pr ocess, you ma y find tha t one or mor e of the solution t echniques not ed in this sec tion helps to acc elerate the c onvergenc e or impr ove the stabilit y of mor e comple x simula tions .The t echniques outlined b elow ma y be of par ticular imp ortanc e if y our pr oblem in volves man y sp ecies and/or chem- ical reactions , esp ecially when mo deling c ombusting flo ws. 15.1.8.1. Stabilit y and C onvergenc e in R eac ting F lows Obtaining a c onverged solution in a r eacting flo w can b e difficult f or a numb er of r easons . First, the impac t of the chemic al reaction on the basic flo w pa ttern ma y be str ong , leading t o a mo del in which ther e is str ong c oupling b etween the mass/momen tum balanc es and the sp ecies tr ansp ort equa tions . This is esp ecially tr ue in c ombustion , wher e the r eactions lead t o a lar ge hea t release and subsequen t densit y changes and lar ge acc elerations in the flo w. All reacting sy stems ha ve some degr ee of c oupling , however, when the flo w pr operties dep end on the sp ecies c oncentrations .These c oupling issues ar e best addr essed b y the use of a t wo-st ep solution pr ocess, as descr ibed b elow, and b y the use of under- relaxa tion as descr ibed in Setting U nder-R elaxa tion F actors (p.2573 ). A sec ond c onvergenc e issue in r eacting flo ws involves the magnitude of the r eaction sour ce term. When the ANSY S Fluen t mo del in volves v ery rapid r eaction r ates (r eaction time sc ales ar e much fast er than c onvection and diffusion time sc ales), the solution of the sp ecies tr ansp ort equa tions b ecomes numer ically difficult. Such sy stems ar e termed “stiff” systems . Stiff sy stems with finit e-rate chemistr y should b e solv ed using either the pr essur e-based or densit y-based solv er together with either Stiff Chemistr y Solver or the CHEMKIN-CFD S olver (see Solution of S tiff C hemistr y Systems (p.1652 )). Finite- rate chemistr y ma y also b e used f or turbulen t combustion. For turbulen t combustion, turbulenc e- chemistr y interactions c an either b e neglec ted ( Finit e-rate/N o TCI mo del) or acc oun ted f or using Eddy-D issipa tion C onc ept or PDF Transp ort mo dels . 15.1.8.2. Two-St ep S olution P rocedur e (St eady -stat e O nly) Solving a r eacting flo w as a t wo-st ep pr ocess is a pr actical metho d for reaching a stable c onverged solution t o your ANSY S Fluen t problem. In this pr ocess, you b egin b y solving the flo w, ener gy, and species equa tions with r eactions disabled (the “cold-flo w”, or unr eacting flo w).When the basic flo w pattern has ther eby been established , you c an r e-enable the r eactions and c ontinue the c alcula tion. The c old-flo w solution pr ovides a go od star ting solution f or the c alcula tion of the c ombusting sy stem. This t wo-st ep appr oach t o combustion mo deling c an b e acc omplished using the f ollowing pr ocedur e: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1650Modeling S pecies Transp ort and F inite-Rate Chemistr y1.Set up the pr oblem including all sp ecies and r eactions of in terest. 2.Temp orarily disable r eaction c alcula tions b y tur ning off Volumetr ic in the Species M odel D ialog Box (p.3294 ). Setup → Models → Species Edit... 3.Disable c alcula tion of the pr oduc t species in the Equa tions D ialog Box (p.3609 ). Solution → Controls → Equa tions ... 4.Calcula te an initial (c old-flo w) solution. (Note tha t it is gener ally not pr oduc tive to obtain a fully c onverged cold-flo w solution unless the non-r eacting solution is also of in terest t o you.) 5.Enable the r eaction c alcula tions b y tur ning on Volumetr ic again in the Species M odel D ialog Box (p.3294 ). 6.Enable all equa tions in the Equa tions dialo g box. If you ar e using the Finit e-Rate/N o TCI,Finit e- Rate/Eddy-D issipa tion ,Eddy-D issipa tion C onc ept or PDF Transp ort mo del f or the turbulenc e- chemistr y interaction, you ma y need t o pa tch an ignition sour ce (as descr ibed in Ignition in S teady-State Combustion S imula tions (p.1651 )). 15.1.8.3. Densit y Under -Relaxation One of the main r easons a c ombustion c alcula tion c an ha ve difficult y converging is tha t lar ge changes in temp erature cause lar ge changes in densit y, which c an, in tur n, cause instabilities in the flo w solution. When y ou use the pr essur e-based solv er, ANSY S Fluen t allo ws you t o under-r elax the change in densit y to alle viate this difficult y.The default v alue f or densit y under-r elaxa tion is 1, but if y ou encoun ter convergenc e trouble y ou ma y want to reduc e this t o a v alue b etween 0.5 and 1 (in the Solution C ontrols task page). Note tha t if y ou ar e using a r eal-gas mo del the solution migh t converge a t a slo wer rate than when running ideal-gas flo w.To impr ove the c onvergenc e performanc e of y our analy sis, you need t o reduc e the under relaxa tion f or densit y to values as lo w as 0.1. 15.1.8.4. Ignition in St eady -Stat e Combustion S imulations If you in troduce fuel t o an o xidan t or ha ve a pr emix ed fuel/o xidan t mix ture, but y ou ar e not simula ting the tr ansien t ignition pr ocess, then y ou must numer ically f orce the solution t o the bur ned sta te (rather than the unbur ned sta te). Gener ally, spontaneous ignition do es not o ccur unless the t emp erature of the mix ture exceeds the ac tivation ener gy thr eshold r equir ed t o main tain c ombustion. For st eady- state ANSY S Fluen t combustion simula tions , whether y ou ar e using the sp ecies tr ansp ort or PDF transp ort mo del and r egar dless of turbulenc e-chemistr y interaction option, you ha ve to supply an ignition sour ce to initia te combustion. This ignition sour ce ma y be a hea ted sur face or inlet mass flow tha t hea ts the gas mix ture ab ove the r equir ed ignition t emp erature. Often, however, it is the equiv alen t of a spar k: an initial solution sta te tha t causes c ombustion t o pr oceed.You c an supply this initial “spar k” by pa tching a hot t emp erature in to a r egion of the ANSY S Fluen t mo del tha t contains an ignitable fuel/air mix ture. Solution → Initializa tion → Patch... Depending on the mo del, you ma y need t o pa tch b oth the t emp erature and the fuel/ o xidan t/produc t concentrations t o pr oduce ignition in y our mo del. The initial pa tch has no impac t on the final st eady- 1651Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Volumetr ic Reactionsstate solution—no mor e than the lo cation of a ma tch det ermines the final flo w pa ttern of the t orch that it ligh ts. See Patching Values in S elec ted C ells (p.2607 ) for details ab out pa tching initial v alues . 15.1.8.5. Solution of Stiff C hemistr y Systems When mo deling stiff chemistr y sy stems , such as flames with finit e-rate kinetics , you c an either use the pr essur e-based solv er with the Stiff C hemistr y Solver option enabled or CHEMKIN-CFD S olver selec ted as seen in the Species M odel D ialog Box (p.3294 ) (Figur e 15.1: The S pecies M odel D ialog Box (p.1617 )), or the densit y-based solv er. For st eady simula tions using the pr essur e-based solv er, the Stiff C hemistr y Solver option appr oxima tes the r eaction r ate in the sp ecies tr ansp ort equa tion (see Equa tion 7.5 in the Theor y Guide ) as, (15.8) wher e is an appr opriate time-st ep. Note tha t as tends t o zero the appr oxima tion b ecomes e xact but the stiff numer ics will c ause the pr essur e-based solv er to div erge. On the other hand , as tends to infinit y, the appr oxima ted r eaction r ate tends t o zero and , while the numer ical stiffness is alle- viated, ther e is no r eaction. In ANSY S Fluen t, the default v alue f or is set t o one-t enth of the minimum convective or diffusiv e time-sc ale in the c ell.This v alue w as found t o be sufficien tly accur ate and r obust , although it c an b e mo dified using the solve/set/stiff-chemistry text command . ISAT is emplo yed t o in tegrate the stiff chemistr y in Equa tion 15.8 (p.1652 ).Equa tion 15.8 (p.1652 ) is also applied for unst eady simula tions , with = flo w time st ep. Details ab out the ISA T algor ithm ma y be found in Particle R eaction in the Theor y Guide and Using ISAT Efficien tly (p.1796 ). For efficien t and accur ate use of ISA T, a review of this sec tion is highly r ecom- mended . The densit y-based implicit solv er ma y also b e used with either chemistr y solv er option. This option allows a lar ger stable C ourant (CFL) numb er sp ecific ation, although additional c alcula tions ar e requir ed to calcula te the eigen values of the chemic al sy stem Jac obian [142] (p.4012 ).When enabling the stiff- chemistr y solv er with the densit y-based solv er, the f ollowing must b e sp ecified: •Temp erature Positivit y Rate Limit : limits new t emp erature changes b y this fac tor multiplied b y the old temp erature. Its default v alue is 0.2. •Temp erature Time S tep Reduc tion : limits the lo cal CFL numb er when the t emp erature is changing t oo rapidly . Its default v alue is 0.25. 15.1.8.6. Eddy -Dissipation C onc ept Mo del S olution P rocedur e Due t o the high c omputa tional e xpense of the E ddy-Dissipa tion C oncept mo del, it is r ecommended that you use the f ollowing pr ocedur e to obtain a solution using the pr essur e-based solv er: 1.Calcula te an initial solution using the equilibr ium N on-pr emix ed or P artially-pr emix ed mo del (see Mod- eling N on-P remix ed C ombustion (p.1687 ) and Modeling P artially P remix ed C ombustion (p.1759 )). 2.Imp ort a CHEMKIN f ormat reaction mechanism (see Imp orting a Volumetr ic Kinetic M echanism in CHEMKIN Format (p.1624 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1652Modeling S pecies Transp ort and F inite-Rate Chemistr y3.Enable the r eaction c alcula tions b y tur ning on Volumetr ic Reac tions in the Species M odel dialo g box and selec ting Eddy-D issipa tion C onc ept under Turbulenc e-Chemistr y In teraction . Selec t the mech- anism tha t you just imp orted as the Mixture M aterial. Setup → Models → Species Edit... 4.Set the sp ecies b oundar y conditions . Setup → Boundar y Conditions 5.Disable the flo w and turbulenc e and solv e for the sp ecies and t emp erature only . 6.Enable all equa tions and it erate to convergenc e. Note tha t the default numer ical par amet ers f or the solution of the E ddy-Dissipa tion C oncept equa tions ar e set t o pr ovide maximum r obustness with slo west convergenc e.The c onvergenc e rate can b e incr eased b y setting the Aggr essiv eness F actor in the Species dialo g box or with the t ext command: define → models → species → set-turb-chem-interaction The Aggr essiv eness F actor can b e set fr om 0 (slo w but stable) t o 1 (fast but least stable). The default is 0.5 15.1.9. Postpr ocessing f or S pecies C alcula tions ANSY S Fluen t can r eport chemic al sp ecies as mass fr actions , mole fr actions , and molar c oncentrations . You c an also displa y laminar and eff ective mass diffusion c oefficien ts.The f ollowing v ariables ar e available f or p ostpr ocessing of sp ecies tr ansp ort and r eaction simula tions: •Mass fr action of sp ecies-n •Mole fr action of sp ecies-n •Molar C onc entration of sp ecies-n •Lam D iff C oef of sp ecies-n •Eff D iff C oef of sp ecies-n •Thermal D iff C oef of sp ecies-n •Enthalp y of sp ecies-n (pressur e-based solv er calcula tions only) •species-n S our ce Term (densit y-based solv er calcula tions only) •Rela tive Humidit y •TFM Thick ening F actor (Thick ened F lame M odel only) •TFM Omega (Thick ened F lame M odel only) •TFM Thick ening F actor (turbulen t cases (LES / DES / SAS / SBES / SDES) with Thick ened F lame M odel only) •Laminar F lame S peed (Thick ened F lame M odel only) 1653Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Volumetr ic Reactions•Laminar F lame Thick ness (Thick ened F lame M odel only) •Cell Time Sc ale (Eddy-Dissipa tion C oncept and laminar finit e-rate with stiff-chemistr y only) •Fine Sc ale M ass fr action of sp ecies-n (Eddy-Dissipa tion C oncept mo del only) •EDC C ell Volume F raction (Eddy-Dissipa tion C oncept mo del only) •Fine Sc ale Temp erature (Eddy-Dissipa tion C oncept mo del only) •Net R ate of sp ecies-n (Eddy-Dissipa tion C oncept and laminar finit e-rate with stiff-chemistr y only) •Kinetic R ate of Reac tion-n •Turbulen t Rate of Reac tion-n •Liquid sp ecies mass fr action of sp ecies-n (solidific ation and melting mo del only) •Heat of Reac tion These v ariables ar e contained in the Species ...,Temp erature..., and Reac tions ... categor ies of the variable selec tion dr op-do wn list tha t app ears in p ostpr ocessing dialo g boxes. See Field F unction Definitions (p.2959 ) for a c omplet e list of flo w variables , field func tions , and their definitions .Displa ying Graphics (p.2775 ) and Reporting A lphanumer ic D ata (p.2909 ) explain ho w to gener ate gr aphics displa ys and r eports of da ta. 15.1.9.1. Averaged Sp ecies C onc entr ations Averaged sp ecies c oncentrations a t inlets and e xits, and acr oss selec ted planes (tha t is, sur faces tha t you ha ve created using Create in the Domain ribbon tab ( Surfacegroup b ox)) within y our mo del can b e obtained using the Surface In tegrals D ialog Box (p.3726 ), as descr ibed in Surface In tegra- tion (p.2947 ). Results → Rep orts → Surface In tegrals Edit... Selec t the Molar C onc entration of sp ecies-n for the appr opriate sp ecies in the Field Variable drop- down list. 15.2. Wall S urface Reac tions and C hemic al Vapor D eposition For gas-phase r eactions , the r eaction r ate is defined on a v olumetr ic basis and the r ate of cr eation and destr uction of chemic al sp ecies b ecomes a sour ce term in the sp ecies c onser vation equa tions . Hetero- geneous sur face reactions cr eate sour ces (and sinks) of chemic al sp ecies in the gas-phase as w ell, but also alt er sur face coverages f or sur face sit e reactions , and ma y dep osit or et ch sp ecies f or bulk (solid) reactions . For mor e inf ormation ab out the theor etical back ground of w all sur face reactions and chemic al vapor dep ositions , see Wall Sur face Reactions and C hemic al Vapor D eposition in the Theor y Guide . Information about using w all sur face reactions is pr esen ted in the f ollowing subsec tions: 15.2.1. Overview of Sur face Species and Wall Sur face Reactions 15.2.2. Imp orting a Sur face Kinetic M echanism in CHEMKIN F ormat 15.2.3. Manual Inputs f or Wall Sur face Reactions 15.2.4. Including M ass Transf er To Sur faces in C ontinuit y Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1654Modeling S pecies Transp ort and F inite-Rate Chemistr y15.2.5. Wall Sur face Mass Transf er Effects in the Ener gy Equa tion 15.2.6. Modeling the H eat Release D ue to Wall Sur face Reactions 15.2.7. Solution P rocedur es for Wall Sur face Reactions 15.2.8. Postpr ocessing f or Sur face Reactions 15.2.1. Overview of S urface Species and Wall S urface Reac tions ANSY S Fluen t treats chemic al sp ecies adsorb ed and desorb ed, as w ell as those dep osited in to or et ched from the bulk solid sur faces as distinc t from the same chemic al sp ecies in the gas . Similar ly, sur face reactions ar e defined distinc tly and tr eated diff erently than gas-phase r eactions in volving the same chemic al sp ecies . Surface reactions c an b e limit ed so tha t the y occur on only some of the w all b oundar ies (while the other w all b oundar ies r emain fr ee of sur face reaction). The sur face reaction r ate is defined and c omput ed per unit sur face ar ea, in c ontrast t o the fluid-phase r eactions , which ar e based on unit v olume . 15.2.2. Imp orting a S urface Kinetic M echanism in CHEMKIN F ormat Imp orting sur face kinetic mechanisms in CHEMKIN f ormat requir es tha t the gas-phase mechanism file accompanies the sur face mechanism file f or full c ompa tibilit y with CHEMKIN (f or mor e inf ormation on how to imp ort the gas-phase mechanism, see Imp orting a Volumetr ic Kinetic M echanism in CHEMKIN Format (p.1624 )). If the gas-phase mechanism file is not a vailable , then y ou will need t o cr eate one tha t you will imp ort along with the sur face mechanism file . The mechanism files ar e imp orted in to ANSY S Fluen t using the Imp ort CHEMKIN F ormat Mechanism dialo g box (Figur e 15.17: The Imp ort CHEMKIN F ormat Mechanism D ialog Box for Sur face Kinetics (p.1656 )) which is op ened b y click ing Imp ort CHEMKIN M echanism... in the Species M odel dialo g box. 1655Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Wall Sur face Reactions and C hemic al Vapor D epositionFigur e 15.17: The Imp ort CHEMKIN F ormat Mechanism D ialo g Box for S urface Kinetics In the Imp ort CHEMKIN F ormat Mechanism dialo g box: 1.Enter a name f or the chemic al mechanism under Material N ame . 2.Enable Imp ort Surface M echanism . 3.Enter the pa ths in the Kinetic Input F ile text fields in the Gas-P hase and Surface group b oxes (f or e xample , path/chem.inp and path / path/surf.inp , respectively). 4.Specify sp ecies ther modynamic pr operty da ta.You c an include the da ta in the k inetics input file and/or in a separ ate file as f ollows: •If you w ant to sp ecify ther modynamic da ta for all sp ecies in the k inetics input file , enable All contained in K inetics Input F ile to avoid the need t o sp ecify a separ ate file . •If you pr ovide some or all sp ecies ther modynamic da ta in a separ ate file , disable All contained in K in- etics Input F ile and sp ecify the ther modynamic da ta file lo cation. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1656Modeling S pecies Transp ort and F inite-Rate Chemistr yYou c an either use the default ther modynamic da tabase file ,thermo.db , provided in the cpropep\data directory in y our ANSY S Fluen t installa tion ar ea or sp ecify the pa th of y our ther- modynamic da tabase file if thermo.db does not c ontain all the gas-phase sp ecies in the CHEMKIN mechanism. The f ormat for thermo.db is detailed in the CHEMKIN manual [59] (p.4008 ). 5.To sp ecify the sur face sp ecies ther modynamic da tabase , you c an: •Selec t All contained in K inetics Input F ile under the Thermodynamic D atabase and include the surface sp ecies ther modynamics da ta in the sur face kinetics input file . •Selec t Same as 'G as-P hase' and include the sur face sp ecies ther modynamics da ta in the ther modynamics data file used in the gas-phase mechanism. Note tha t the default thermo.db file c ontains only gas- phase sp ecies . If you w ant to use this file , you will need t o supply a ther modynamic da tabase tha t includes surface sp ecies defined in y our simula tion. Note The sur face sp ecies ther modynamic da ta must b e included either in the sur face kinetics input file or in the gas-phase ther modynamics da ta file . If you do not imp ort ther mody- namics da ta as a separ ate file in the gas-phase mechanism, then all sur face ther mody- namics da ta must b e contained in the sur face kinetics input file . 6.Click the Imp ort butt on. ANSY S Fluen t will cr eate a ma terial with the sp ecified name , which will c ontain the CHEMKIN da ta for the sp ecies and r eactions , and add it t o the list of Fluen t Mixture M aterials.You c an view all of the reactions b y click ing the Edit... butt on t o the r ight of Mechanism , under Properties in the Create/Edit Materials D ialog Box (p.3386 ). ANSY S Fluen t will also aut oma tically sa ve the imp orted da ta within the F luen t case file . Note tha t carrying the or iginal input files along with the F luen t case file is not r equir ed. ANSY S Fluen t will aut o- matically r etrieve these files when needed (f or e xample , when using the CHEMKIN-CFD solv er). For details on imp orting gas sp ecies tr ansp ort properties, see Procedur e for Imp orting Volumetr ic CHEMKIN M echanisms (p.1625 ). Imp ortant A sur face reaction r ate constan t can b e expressed in t erms of a stick ing c oefficien t in CHEMKIN mechanisms .When Stiff C hemistr y Solver is selec ted fr om the Chemistr y Solver drop-do wn list , ANSY S Fluen t will c onvert this stick ing c oefficien t form to an equiv alen t Arrhenius r ate expression [58] (p.4008 ). For full c ompa tibilit y with ANSY S Chemk in-P ro, selec t CHEMKIN-CFD S olver inst ead. 15.2.2.1. Compatibilit y and Limitations for G as P hase R eac tions Gener ally, ANSY S Fluen t handles all r eaction t ypes tha t are supp orted in ANSY S Chemk in-P ro. However, some limita tions still e xist f or the f ollowing mo dels and f eatures: •the None – E xplicit S our ce chemistr y solv er (non-stiff chemistr y) 1657Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Wall Sur face Reactions and C hemic al Vapor D eposition•the Finit e-Rate/Eddy-D issipa tion turbulenc e-chemistr y interaction In these c ases , only the f ollowing v olume r eaction t ypes c an b e used: •Arrhenius , including those r eactions with arbitr ary reaction or der, thir d-body efficiencies and non-in teger stoichiometr ic coefficien ts •Pressur e-dep enden t reactions using the Lindemann, Troe and SRI f orms •CHEMKIN mechanism files with CHEMKIN-default r ate par amet er units •Duplic ate reactions (k eyword DUP) •Arbitr ary reverse r eaction (k eyword RE V) 15.2.2.2. Compatibilit y and Limitations for S urface Reac tions When using sur face reactions in y our simula tion, not e the f ollowing: •Surface reactions ar e not supp orted with the densit y-based solv er. •As with v olume r eactions , ANSY S Fluen t gener ally handles all r eaction t ypes tha t are supp orted in ANSY S Chemk in-P ro. However, with the None – E xplicit S our ce chemistr y solv er or Finit e-Rate/Eddy-D issipa tion turbulenc e-chemistr y interaction, only the f ollowing sur face reaction t ypes c an b e used: –Arrhenius r eactions , including those with arbitr ary reaction or der, thir d-body efficiencies and non-in teger stoichiometr ic coefficien ts –Sticking c oefficien ts (k eyword STICK). ANSY S Fluen t converts these t o an equiv alen t Arrhenius e xpression. –Arbitr ary reaction units –Duplic ate reactions (k eyword DUP) –Surface coverage mo dific ation (k eyword COV) For a detailed descr iption of the k eywords, see ANSY S Chemk in-P ro Input M anual. 15.2.3. Manual Inputs f or Wall S urface Reac tions The basic st eps f or setting up a pr oblem in volving w all sur face reactions ar e the same as those presen ted in Overview of U ser Inputs f or M odeling S pecies Transp ort and R eactions (p.1614 ) for setting up a pr oblem with only fluid-phase r eactions , with a f ew additions: 1.In the Species M odel D ialog Box (p.3294 ): Setup → Models → Species Edit... a.Enable Species Transp ort, selec t Volumetr ic and Wall S urface under Reac tions , and sp ecify the Mixture M aterial. See Enabling S pecies Transp ort and R eactions and C hoosing the M ixture Materi- al (p.1616 ) for details ab out this pr ocedur e, and Mixture Materials (p.1615 ) for an e xplana tion of the mixture ma terial c oncept. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1658Modeling S pecies Transp ort and F inite-Rate Chemistr yb.(optional) I f you w ant to mo del the hea t release due t o wall sur face reactions , enable the Heat of Surface Reac tions option. c.(optional) I f you w ant to include the eff ect of sur face mass tr ansf er in the c ontinuit y equa tion, enable the Mass D eposition S our ce option. d.To control the r obustness and the c onvergenc e sp eed, enter a v alue b etween 0 and 1 f or the Aggr ess- iveness F actor. A value of 0 is the most r obust , but r esults in the slo west c onvergenc e.The default value f or the Aggr essiv eness F actor is 0.5. e.(optional) I f you ar e using the pr essur e-based solv er and y ou w ant to include sp ecies diffusion eff ects in the ener gy equa tion, enable the Diffusion E nergy Sour ce option. See Wall Sur face Mass Transf er Effects in the Ener gy Equa tion (p.1660 ) for details . f.(optional, but r ecommended f or CVD) I f you w ant to mo del full multic omp onen t (Stefan-M axwell) diffusion or ther mal (S oret) diffusion, enable the Full M ultic omp onen t Diffusion or Thermal D iffusion option. See Full M ultic omp onen t Diffusion (p.1142 ) for details . 2.Check and/or define the pr operties of the mix ture. See Defining P roperties f or the M ixture and I ts Con- stituen t Species (p.1629 ). Setup → Materials Mixture pr operties include the f ollowing: •species in the mix ture •reactions •other ph ysical pr operties (f or e xample , visc osity, specific hea t) Imp ortant •You will find all sp ecies (including the solid/bulk and sit e sp ecies) in the list of Fluen t Fluid Materials. For a dep osited sp ecies such as S i, you will need b oth S i(g) and S i(s) in the ma ter- ials list f or the fluid material type. •Note tha t the final gas-phase sp ecies named in the Selec ted S pecies list should b e the c ar- rier gas .This is b ecause ANSY S Fluen t will not solv e the tr ansp ort equa tion f or the final species . Note also tha t an y reordering, adding or deleting of sp ecies should b e handled with caution, as descr ibed in Assigning the Last S pecies (p.1633 ). 3.Check and/or set the pr operties of the individual sp ecies in the mix ture. (See Defining P roperties f or the Mixture and I ts Constituen t Species (p.1629 ).) Note tha t if y ou ar e mo deling the hea t of sur face reactions , you should b e sur e to check (or define) the f ormation en thalp y for each sp ecies . 4.Set sp ecies b oundar y conditions . Setup → Boundar y Conditions In addition t o the b oundar y conditions descr ibed in Defining C ell Z one and B oundar y Conditions for S pecies (p.1649 ), you will first need t o indic ate whether or not sur face reactions ar e in eff ect on 1659Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Wall Sur face Reactions and C hemic al Vapor D epositioneach w all. If so, you will then need t o assign a r eaction mechanism t o the w all.To enable the eff ect of sur face reaction on a w all, enable the Reac tion option in the Species sec tion of the Wall dialo g box. Imp ortant If you ha ve enabled the global Low-P ressur e Boundar y Slip option in the Viscous Model D ialog Box (p.3253 ), the Shear C ondition for each w all will b e reset t o No Slip even though the slip mo del will b e in eff ect. Note tha t the Low-P ressur e Boundar y Slip option is a vailable only when the Laminar mo del is selec ted in the Visc ous M odel dialo g box. See Inputs a t Wall B oundar ies (p.971) for details ab out b oundar y condition inputs f or w alls. See User Inputs f or P orous M edia (p.872) for details ab out b oundar y condition inputs f or p orous media. 15.2.4. Including M ass Transf er To Surfaces in C ontinuit y In the sur face reaction b oundar y condition descr ibed ab ove, the eff ects of the w all nor mal v elocity or bulk mass tr ansf er to the w all ar e not included in the c omputa tion of sp ecies tr ansp ort.The momen tum of the net sur face mass flux fr om the sur face is also ignor ed b ecause the momen tum flux thr ough the surface is usually small in c ompar ison with the momen tum of the flo w in the c ells adjac ent to the surface. However, you c an include the eff ect of sur face mass tr ansf er in the c ontinuit y equa tion b y activating the Mass D eposition S our ce option in the Species M odel D ialog Box (p.3294 ). 15.2.5. Wall S urface M ass Transf er E ffects in the E nergy Equa tion Species diffusion eff ects in the ener gy equa tion due t o wall sur face reactions ar e included in the nor mal species diffusion t erm descr ibed in Treatmen t of S pecies Transp ort in the Ener gy Equa tion in the Theor y Guide . If you ar e using the pr essur e-based solv er, you c an neglec t this t erm b y disabling the Diffusion E nergy Sour ce option in the Species M odel D ialog Box (p.3294 ). For the densit y-based solv ers, this t erm is alw ays included; you c annot disable it. Neglec ting the sp ecies diffusion t erm implies tha t errors ma y be in tro- duced t o the pr edic tion of t emp erature in pr oblems in volving mixing of sp ecies with signific antly dif- ferent hea t capacities , esp ecially f or c omp onen ts with a L ewis numb er far fr om unit y.While the eff ect of sp ecies diffusion should go t o zero at Le = 1, you ma y see subtle eff ects due t o diff erences in the numer ical in tegration in the sp ecies and ener gy equa tions . 15.2.6. Modeling the H eat Release D ue t o Wall S urface Reac tions The hea t release due t o a w all sur face reaction is , by default , ignor ed b y ANSY S Fluen t.You c an, however, cho ose t o include the hea t of sur face reaction b y ac tivating the Heat of S urface Reac tions option in the Species M odel D ialog Box (p.3294 ) and setting appr opriate formation en thalpies in the Edit M aterial D ialog Box (p.3442 ). 15.2.7. Solution P rocedur es for Wall S urface Reac tions As in all CFD simula tions , your sur face reaction mo deling eff ort ma y be mor e succ essful if y ou star t with a simple pr oblem descr iption, adding c omple xity as the solution pr oceeds . For w all sur face reac- tions , you c an f ollow the same guidelines pr esen ted f or fluid-phase r eactions in Solution P rocedur es for C hemic al M ixing and F inite-Rate Chemistr y (p.1650 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1660Modeling S pecies Transp ort and F inite-Rate Chemistr yIn addition, if y ou ar e mo deling the hea t release due t o sur face reactions and y ou ar e ha ving c onver- genc e trouble , you should tr y temp orarily tur ning off the Heat of S urface Reac tions and Mass D epos- ition S our ce options in the Species M odel D ialog Box (p.3294 ). If you ar e mo deling sur face sit e sp ecies , good estima tes of the Initial S ite Coverage will aid c onver- genc e. 15.2.8. Postpr ocessing f or S urface Reac tions In addition t o the gas-phase v ariables list ed in Postpr ocessing f or S pecies C alcula tions (p.1653 ), for surface reactions y ou c an displa y/report the sur face coverage as w ell as the dep osition r ate of the solid sp ecies dep osited on a sur face. Selec t Surface Coverage of sp ecies-n ,Surface D eposition R ate of sp ecies-n , or Porous D eposition R ate of sp ecies-n in the Species ... categor y of the v ariable selec tion drop-do wn list. Imp ortant For sur face reactions in volving p orous media, you c an displa y/report the sur face reaction rates using the Kinetic R ate of Reac tion-n(P orous) in the Reac tions ... categor y of the variable selec tion dr op-do wn list. 15.3. Particle S urface Reac tions As descr ibed in The M ultiple Sur face Reactions M odel in the Theor y Guide , it is p ossible t o define multiple particle sur face reactions t o mo del the sur face combustion of a c ombusting discr ete-phase par ticle . For mor e inf ormation ab out the theor etical back ground of par ticle sur face reactions , see Particle Sur face Reactions in the Theor y Guide . Information ab out using par ticle sur face reactions is pr ovided in the following subsec tions: 15.3.1. User Inputs f or P article Sur face Reactions 15.3.2. Modeling G aseous S olid C atalyz ed R eactions 15.3.3. Using the M ultiple Sur face Reactions M odel f or D iscrete-Phase P article C ombustion 15.3.1. User Inputs f or P article S urface Reac tions The setup pr ocedur e for par ticle sur face reactions r equir es only a f ew inputs in addition t o the pr ocedur e for v olumetr ic reactions descr ibed in Overview of U ser Inputs f or M odeling S pecies Transp ort and R e- actions (p.1614 ) – Defining O ther S ources of C hemic al Species (p.1650 ).These additional inputs ar e as follows: •In the Species M odel dialo g box, enable the Particle S urface option under Reac tions . Setup → Models → Species Edit... 1661Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Particle Sur face Reactions•When y ou sp ecify the sp ecies in volved in the par ticle sur face reaction, be sur e to iden tify the sur face sp ecies , as descr ibed in Defining P roperties f or the M ixture and I ts Constituen t Species (p.1629 ). Imp ortant You will find all sp ecies (including the sur face sp ecies) in the list of Fluen t Fluid M aterials. If, for e xample , you ar e mo deling c oal gasific ation, you will find solid c arbon, C(s), in the materials list f or the fluid ma terial t ype. •For each par ticle sur face reaction, selec t Particle S urface as the Reac tion Type in the Reac tions dialo g box, and sp ecify the f ollowing par amet ers (in addition t o those descr ibed in Defining R eactions (p.1634 )): Diffusion-Limit ed S pecies When ther e is mor e than one gaseous r eactant tak ing par t in the par ticle sur face reaction, the diffusion- limit ed sp ecies is the sp ecies f or which the c oncentration gr adien t between the bulk and the par ticle surface is the lar gest. See Figur e 7.1: A R eacting P article in the M ultiple Sur face Reactions M odel in the Theor y Guide for an illustr ation of this c oncept. In most c ases , ther e is a single gas-phase r eactant and the diffusion-limit ed sp ecies do es not need t o be defined . Cataly st S pecies This option is a vailable only when ther e are no solid sp ecies defined in the st oichiometr y of the par ticle surface reaction. In such a c ase, you will need t o sp ecify the solid sp ecies tha t acts as a c atalyst for the reaction. The r eaction will pr oceed only on the par ticles tha t contain this solid sp ecies . See Using the Multiple Sur face Reactions M odel f or D iscrete-Phase P article C ombustion (p.1662 ) for details on defining the par ticle sur face sp ecies mass fr actions . Diffusion R ate Constan t ( in Equa tion 7.75 in the Theor y Guide ) Effectiveness F actor ( in Equa tion 7.73 in the Theor y Guide ) 15.3.2. Modeling G aseous S olid C atalyz ed Reac tions The c atalytic par ticle sur face reaction option is enabled in ANSY S Fluen t when Particle S urface is se- lected as the Reac tion Type in the Reactions D ialog Box (p.3419 ) and ther e ar e no solid sp ecies in the reaction st oichiometr y.The solid sp ecies ac ting as a c atalyst for the r eaction is defined in the Reac tions dialo g box.The c atalytic par ticle sur face reaction will pr oceed only on those par ticles c ontaining the catalyst sp ecies . 15.3.3. Using the M ultiple S urface Reac tions M odel f or D iscrete-Phase P article Combustion When y ou use the multiple sur face reactions mo del, the pr ocedur e for setting up a pr oblem in volving a discr ete phase is sligh tly diff erent from tha t outlined in Steps f or U sing the D iscrete Phase M od- els (p.1917 ).The r evised pr ocedur e is as f ollows: 1.Enable an y of the discr ete phase mo deling options , if relevant, as descr ibed in Physical M odels f or the Discrete Phase M odel (p.1925 ). 2.Specify the initial c onditions , as descr ibed in Setting Initial C onditions f or the D iscrete Phase (p.1943 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1662Modeling S pecies Transp ort and F inite-Rate Chemistr y3.Define the b oundar y conditions , as descr ibed in Setting B oundar y Conditions f or the D iscrete Phase (p.1985 ). 4.Define the ma terial pr operties, as descr ibed in Setting M aterial P roperties f or the D iscrete Phase (p.2008 ). Imp ortant You must selec t multiple-sur face-reac tions in the Combustion M odel drop-do wn list in the Create/Edit M aterials dialo g box before you c an pr oceed t o the ne xt step. 5.If you ha ve defined mor e than one par ticle sur face sp ecies , for e xample , carbon ( C ) and sulfur ( S ), you will need t o retur n to the Set Injec tion P roperties dialo g box (or Set M ultiple Injec tion P roperties dialo g box) to sp ecify the mass fr action of each par ticle sur face sp ecies in the c ombusting par ticle . Click the Multiple Reac tions tab , and en ter the Species M ass F ractions .These mass fr actions r efer to the combustible fr action of the c ombusting par ticle , and should sum t o 1. If ther e is only one sur face sp ecies in the mix ture ma terial, the mass fr action of tha t species will b e set t o 1, and y ou will not sp ecify an ything under Multiple S urface Reac tions . 6.Set the solution par amet ers and solv e the pr oblem, as descr ibed in Solution S trategies f or the D iscrete Phase (p.2022 ). 7.Examine the r esults , as descr ibed in Postpr ocessing f or the D iscrete Phase (p.2027 ). Imp ortant Solid dep osition r eactions on the par ticle ar e not allo wed t ogether with cust om la ws. 15.4. Electrochemic al Reac tions Similar t o wall sur face reactions , elec trochemic al reactions gener ate sour ces (and sinks) in chemic al species tr ansp ort equa tions . For mor e inf ormation ab out the theor etical back ground of elec trochemic al reactions , see Electrochem- ical Reactions in the Fluent Theor y Guide . Information ab out using elec trochemic al reactions is pr esen ted in the f ollowing sec tions: 15.4.1. Overview of E lectrochemic al Reactions 15.4.2. User Inputs f or Electrochemic al Reactions 15.4.3. Electrochemic al Reaction E ffects in the Ener gy Equa tion 15.4.4. Electrochemic al Reaction E ffects in the S pecies Transp ort Equa tion 15.4.5. Including M ass Transf er in C ontinuit y 15.4.6. Solution P rocedur es for Electrochemic al Reactions 15.4.1. Overview of E lectrochemic al Reac tions An elec trochemic al reaction o ccurs only on w all sur faces wher e the elec trolyt e and the elec trode meet. Both aqueous and solid sp ecies c an par ticipa te in elec trochemic al reactions . Solid sp ecies tha t can b e involved in elec trochemic al reactions ar e corroded or dep osited sp ecies . Electrochemic al reactions c an b e limit ed so tha t the y can only o ccur on some of the w all b oundar ies (while the other w all b oundar ies r emain fr ee of r eaction). The r eaction r ate is defined and c omput ed per unit sur face ar ea, in c ontrast t o the fluid-phase r eactions , which ar e based on unit v olume . 1663Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Electrochemic al ReactionsYou c an sp ecify diff erent reaction mechanisms f or diff erent walls. Each r eaction mechanism c an ha ve multiple elec trochemic al reactions . 15.4.2. User Inputs f or E lectrochemic al Reac tions The st eps needed t o inc orporate elec trochemic al reactions in y our pr oblem ar e as f ollows: 1.For unst eady simula tions , selec t Transien t from the Gener al task page ( Solver group). 2.Enable chemic al sp ecies tr ansp ort mo del. Setup → Models → Species Edit... Figur e 15.18: The S pecies M odel D ialo g Box with E lectrochemic al Reac tions E nabled a.In the Species M odel dialo g box, under Model, enable Species Transp ort. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1664Modeling S pecies Transp ort and F inite-Rate Chemistr yb.Under Reac tions , selec t Volumetr ic and Electrochemic al. Note Onc e you enable the Electrochemic al reactions , the elec tric potential solv er will b e automa tically enabled (under the Models tree br anch). 3.In the Create/Edit M aterials dialo g box, define all the sp ecies ma terials tha t are pr esen t in the elec trolyt e and elec trodes. Setup → Materials a.Copy the new sp ecies fr om the F luen t da tabase t o your c ase as descr ibed in Copying M aterials fr om the ANSY S Fluen t Database (p.1084 ). If your sp ecies ma terial is not pr esen t in the da tabase , copy a similar sp ecies ma terial and edit its pr operties, including Name and Chemic al F ormula . Note •When c opying sp ecies (including c orroded and dep osited solid sp ecies), mak e sur e tha t fluid is selec ted as Material Type in the Fluen t Database M aterials dialo g box. •It is not nec essar y to represen t the elec tron in the r eaction, and e- can b e saf ely ignor ed. b.Under the Properties group b ox, set Charge N umb er for the new sp ecies . Imp ortant By default ,Charge N umb er is set t o 0, which means tha t the sp ecies is neutr al. Make sure to sp ecify the Charge N umb er for all r elevant sp ecies . Note Do not sp ecify Electrical C onduc tivit y for individual sp ecies .You will sp ecify Elec- trical C onduc tivit y for the mix ture. 4.Edit the mix ture comp osition using the Species dialo g box (op ened b y click ing Edit next to Mixture Species under Properties of the Create/Edit M aterials dialo g box). a.Remo ve unused sp ecies and add the elec trochemic al sp ecies t o the Selec ted S pecies list as descr ibed in Adding S pecies t o the M ixture (p.1632 ). 1665Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Electrochemic al Reactionsb.If solid sp ecies ar e involved in the elec trochemic al reactions (f or e xample , in c orrosion or elec tropla ting simula tions), add them t o the Selec ted S olid S pecies list. Note Make sur e tha t the bulk sp ecies is the last sp ecies in the Selec ted S pecies list. ANSY S Fluen t solv es tr ansp ort equa tions f or all but the last sp ecies in the Selec ted S pecies list. The or der of the solution is the same as the or der of the sp ecies in Selec ted Species . 5.Specify the r eactions in the Reac tions dialo g box (op ened b y click ing Edit next to Reac tions under Properties of the Create/Edit M aterials dialo g box). Figur e 15.19: The Reac tions D ialo g Box Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1666Modeling S pecies Transp ort and F inite-Rate Chemistr yFor each r eaction, configur e the f ollowing settings: a.Selec t Electrochemic al as the r eaction t ype. b.If you w ant the Tafel Equa tion 7.85 in the Fluent Theor y Guide , rather than the B ulter-V olmer Equa- tion 7.84 , to be used in the k inetics c alcula tion, selec t Tafel P aramet ers. c.Specify the f ollowing Butler-V olmer/T afel P aramet ers: •Butler-V olmer par amet ers (the Tafel P aramet ers check b ox is clear ed): –Anodic Transf er C oefficien t ( in Equa tion 7.84 in the Fluent Theor y Guide ) –Catho dic Transf er C oefficien t ( in Equa tion 7.84 in the Fluent Theor y Guide ) •Tafel par amet ers (the Tafel P aramet ers check b ox is selec ted): –Anodic Tafel S lope ( in Equa tion 7.85 in the Fluent Theor y Guide ) –Catho dic Tafel S lope ( in Equa tion 7.85 in the Fluent Theor y Guide ) •Exchange C urrent Densit y ( in Equa tion 7.84 in the Fluent Theor y Guide ) •Equilibr ium P otential ( in Equa tion 7.86 in the Fluent Theor y Guide ) You c an define a constan t,polynomial ,piec ewise-linear , or user-defined func tion f or an y of the af oremen tioned B utler-V olmer/T afel par amet ers. d.Enter the th species dimensionless p ower ( in Equa tion 7.84 in the Fluent Theor y Guide ) as Rate Exponen t. e.Under the Butler-V olmer/T afel P aramet ers group b ox, click the Specify Ref erenc e M ass F ractions ... butt on and in the Referenc e M ass F ractions dialo g box tha t op ens, enter the r eference sp ecies mass fractions ( in Equa tion 7.84 in the Fluent Theor y Guide ). Note You c an cust omiz e the elec trochemic al reaction r ate by using the f ollowoing UDFs: •DEFINE_EC_KINETICS_PARAMETER : to cust omiz e an individual k inetics par amet er in the B utler-V olmer r eaction r ate •DEFINE_EC_RATE : to define a t otally diff erent func tion f orm for the r eaction r ate. Refer to DEFINE_EC_KINETICS_PARAMETER and DEFINE_EC_RATE in the Fluent C ustomization Manual for details ab out those func tions . 6.Define r eaction mechanisms using the Reac tion M echanisms dialo g box (op ened b y click ing Edit next to Mechanism under Properties of the Create/Edit M aterials dialo g box). 1667Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Electrochemic al ReactionsFigur e 15.20: The Reac tion M echanisms D ialo g Box a.Specify Numb er of M echanisms . If you t ype in the v alue , be sur e to pr ess Enter. b.For each elec trochemic al reaction mechanism, configur e the f ollowing settings: i.Set the Mechanism ID of the mechanism y ou w ant to define . Again, if you t ype in the v alue , be sure to pr ess Enter. ii.Selec t Electrochemic al as a r eaction t ype. iii.Under Reac tions , selec t the r eaction and in the Name text en try field , specify a meaning ful name for the mechanism (f or e xample ,mechanism-anode or mechanism-cathode ). 7.In the Create/Edit M aterials dialo g box, set the r emaining mix ture pr operties, such as Densit y (typic ally volume-w eigh ted-mixing-la w),Mass D iffusivit y, and Electrical C onduc tivit y. Note tha t if the ano de, cathode, and elec trolyt e ha ve diff erent ma terial pr operties, such as sp ecies mass diffusivities , it is b est t o use a UDF . Alternatively, you c an cr eate new ma terials f or the ano de and c athode b y copying e xisting ma terials fr om the F luen t da tabase , renaming them, and then assigning these ma terials t o the ano de and c athode fluid z ones in the Cell Z one C onditions dialo g box. 8.For elec trolyt e and elec trode z ones , set c ell z one c onditions using Cell Z one C onditions Task P age (p.3455 ). Setup → Cell Z one C onditions a.In the Fluid dialo g box, specify whether or not the selec ted z one is an elec trolyt e zone b y selec ting or clear ing the Electrolyt e check b ox. By default , all fluid z ones ar e elec trolyt e zones . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1668Modeling S pecies Transp ort and F inite-Rate Chemistr yb.If ther e is no v olumetr ic reactions , clear the Reac tion check b ox. 9.Set the elec trochemic al boundar y conditions f or all r elevant walls using Boundar y Conditions Task Page (p.3479 ). Setup → Boundar y Conditions Figur e 15.21: Wall P otential B oundar y Condition Electrochemic al reaction c an b e defined a t either e xterior (1-sided) w alls or in terior (2-sided) w alls with only one side e xposed t o elec trolyt e. In the Wall dialo g box, configur e the f ollowing settings: a.For e xterior (1-sided) w alls, set the p otential b oundar y conditions as descr ibed in Using the E lectric Potential M odel (p.2351 ). b.Specify whether or not the w all is F aradaic b y selec ting or clear ing the Electrochemic al Reac tion check b ox. c.For Faradaic w alls, from the Reac tion M echanism drop-do wn list , selec t the r eaction mechanism tha t you ha ve pr eviously defined . d.If the elec trochemic al reaction is defined on the w all (Electrochemic al Reac tion is selec ted), you c an include the r eaction hea t in the ener gy equa tion b y selec ting the Faradaic H eat check b ox. Note For the 2-sided w all, you need t o sp ecify the p otential b oundar y conditions only on one side of the w all.The settings y ou ha ve sp ecified will b e aut oma tically c opied t o the other side of the w all. 10.(optional) You c an include additional sour ces in the ener gy, continuit y, and sp ecies tr ansp ort equa tions as descr ibed in the f ollowing sec tions: 1669Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Electrochemic al Reactions•Electrochemic al Reaction E ffects in the Ener gy Equa tion (p.1670 ) •Electrochemic al Reaction E ffects in the S pecies Transp ort Equa tion (p.1671 ) •Including M ass Transf er in C ontinuit y (p.1671 ). 11.Set the solution par amet ers in the Solution M etho ds Task P age (p.3603 ) and Solution C ontrols Task Page (p.3606 ). In man y elec trochemic al applic ations , fluid c onvection c an b e neglec ted, in which c ase the Flow equa tion should b e disabled in the Equa tions control b ox (acc essible fr om the Solution C ontrols Task P age (p.3606 )). Similar ly, for isother mal simula tions , the Energy equa tion should b e disabled . Imp ortant If the p otential equa tion has difficult y converging , you c an lo wer the Faradaic In terface Current under-r elaxa tion fac tor in the Solution C ontrols task page t o impr ove stabilit y. 12.Onc e the solution is c onverged , you c an displa y or r eport the f ollowing v ariables tha t are available under the Potential categor y: •Electric P otential •Electric C onduc tivit y •Faradaic C urrent Densit y •Total S urface Corrosion R ate •Electrode S urface Potential •Current Densit y •Joule H eat Sour ce •Faradaic H eat Sour ce •Total E chem H eat Sour ce In addition, you c an displa y •Echem Reac tion R ate of each r eactions (under the Reac tions categor y) •Surface Corrosion R ate of each solid sp ecies on a w all (under Species categor y) 15.4.3. Electrochemic al Reac tion E ffects in the E nergy Equa tion When the elec trochemic al reaction mo del is enabled , you c an sp ecify t wo extra sour ces in the ener gy equa tion: •Joule hea ting in the fluid and solid z ones Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1670Modeling S pecies Transp ort and F inite-Rate Chemistr yYou c an include the J oule hea ting in the ener gy equa tion c alcula tion b y selec ting the Include J oule Heating in E nergy Equa tion option in the Electric P otential dialo g box (Using the E lectric Potential Model (p.2351 )). •Electrochemic al reaction hea t at Faradaic in terfaces You c an include the elec trochemic al reaction hea t by selec ting the Faradaic H eat option in the boundar y condition dialo g boxes for each r eacting w all. 15.4.4. Electrochemic al Reac tion E ffects in the S pecies Transp ort Equa tion When the elec trochemic al reaction mo del is enabled , you c an sp ecify an e xtra sour ce in the sp ecies transp ort equa tion f or the ion-sp ecies: •Species migr ation in the elec tric field You c an include this eff ect by selec ting the Species M igration option in the Species M odel D ialog Box (p.3294 ). 15.4.5. Including M ass Transf er in C ontinuit y When a solid sp ecies (c orroded or dep osited) is in volved in an elec trochemic al reaction, the solid ma- terial c an en ter or lea ve the flo w domain. Usually the mass tr ansf er of the solid sp ecies is small and can b e ignor ed in the c ontinuit y equa tion. However, if y ou w ant, you c an include the mass sour ce in the c ontinuit y equa tion b y using the f ollowing Scheme c ommand: (rpsetvar ‘potential/corrosion-source-in-continuity? #t) 15.4.6. Solution P rocedur es for E lectrochemic al Reac tions The str ongly nonlinear c oupling b etween sp ecies and elec tric field c an c ause c onvergenc e pr oblems . To impr ove the stabilit y of the solution, you c an lo wer the Faradaic In terface Current under-r elaxa tion factor in the Solution C ontrols Task P age (p.3606 ). In addition, you c an tr y temp orarily disabling the Include J oule H eating in E nergy Equa tion and Faradaic H eat options (see Electrochemic al Reaction E ffects in the Ener gy Equa tion (p.1670 )). You c an enable these options onc e the solution b ecomes mor e stable . 15.5. Species Transp ort Without Reac tions In addition t o the v olumetr ic and sur face reactions descr ibed in the pr evious sec tions , you c an also use ANSY S Fluen t to solv e a sp ecies mixing pr oblem without r eactions .The sp ecies tr ansp ort equa tions that ANSY S Fluen t will solv e ar e descr ibed in Volumetr ic Reactions in the Theor y Guide , and the pr ocedur e you will f ollow to set up the non-r eacting sp ecies tr ansp ort problem is the same as tha t descr ibed in Overview of U ser Inputs f or M odeling S pecies Transp ort and R eactions (p.1614 ) – Defining O ther S ources of C hemic al Species (p.1650 ), with some simplific ations . The basic st eps ar e list ed b elow: 1.Enable Species Transp ort in the Species M odel dialo g box and selec t the appr opriate Mixture M aterial. 1671Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Species Transp ort Without R eactionsSetup → Models → Species Edit... See Overview of U ser Inputs f or M odeling S pecies Transp ort and R eactions (p.1614 ) for inf ormation about the mix ture ma terial c oncept, and Enabling S pecies Transp ort and R eactions and C hoosing the M ixture M aterial (p.1616 ) for mor e details ab out using the Species M odel dialo g box. 2.(optional) I f you w ant to mo del full multic omp onen t (Stefan-M axwell) diffusion or ther mal (S oret) diffusion, enable the Full M ultic omp onen t Diffusion or Thermal D iffusion option. 3.Check and/or define the pr operties of the mix ture and its c onstituen t species . Setup → Materials Mixture pr operties include the f ollowing: •species in the mix ture •other ph ysical pr operties (f or e xample , visc osity, specific hea t) See Defining P roperties f or the M ixture and I ts C onstituen t Species (p.1629 ) for details . 4.Set sp ecies b oundar y conditions , as descr ibed in Defining C ell Z one and B oundar y Conditions f or S pe- cies (p.1649 ). No sp ecial solution pr ocedur es ar e usually r equir ed f or a non-r eacting sp ecies tr ansp ort calcula tion. Upon c ompletion of the c alcula tion, you c an displa y or r eport the f ollowing quan tities: •Mass fr action of sp ecies-n •Mole fr action of sp ecies-n •Conc entration of sp ecies-n •Lam D iff C oef of sp ecies-n •Eff D iff C oef of sp ecies-n •Enthalp y of sp ecies-n (pressur e-based solv er calcula tions only) •Rela tive Humidit y (when the w ater vapors (H2O) is pr esen t in the sp ecies mix ture ma terial) •Mean M olecular Weigh t •Liquid sp ecies mass fr action of sp ecies-n (solidific ation and melting mo del only) These v ariables ar e contained in the Species ... and Properties ... categor ies of the v ariable selec tion drop-do wn list tha t app ears in p ostpr ocessing dialo g boxes. See Field F unction D efinitions (p.2959 ) for a complet e list of flo w variables , field func tions , and their definitions .Displa ying G raphics (p.2775 ) and Reporting A lphanumer ic D ata (p.2909 ) explain ho w to gener ate gr aphics displa ys and r eports of da ta. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1672Modeling S pecies Transp ort and F inite-Rate Chemistr y15.6. Reac ting C hannel M odel Information ab out using the r eacting channel mo del is pr esen ted in the f ollowing subsec tions . For mor e information ab out the theor etical back ground , see Reacting C hannel M odel in the Theor y Guide . 15.6.1. Overview and Limita tions of the R eacting C hannel M odel 15.6.2. Enabling the R eacting C hannel M odel 15.6.3. Boundar y Conditions f or C hannel Walls 15.6.4. Postpr ocessing f or R eacting C hannel M odel C alcula tions 15.6.1. Overview and Limita tions of the Reac ting C hannel M odel The r eacting channel mo del in ANSY S Fluen t off ers an efficien t solution metho dolo gy for solving r eacting flow in shell and tub e hea t exchangers with long and thin channels .The v olume inside the r eacting channels is not meshed and solv ed with the out er flo w. Inst ead, a plug flo w appr oxima tion is used f or the r eacting channels , which is c oupled t o the out er flo w thr ough hea t transf er acr oss the channel walls. The r eacting channel mo del has the f ollowing limita tions: •The r eacting channel mo del is a vailable only f or st eady-sta te 3D pr oblems . •The r eacting channel mo del solv es the one-dimensional sp ecies equa tions a t the c enterline of the r eacting channel. The accur acy of the mo del dep ends on ho w w ell ANSY S Fluen t comput es the channel c enterline from the channel w all sur face mesh. It is highly r ecommended t o use a sw ept str uctured sur face mesh on the channel w all (see Figur e 15.22: Optimal Sur face Mesh on the R eacting C hannel Wall (p.1673 )). Unstr uctured channel w all sur face meshes ma y result in loss of accur acy due t o inc onsist ent channel c enterlines . Figur e 15.22: Optimal S urface M esh on the Reac ting C hannel Wall 15.6.2. Enabling the Reac ting C hannel M odel The st eps and pr ocedur e to set up a r eacting channel mo del ar e outlined b elow. In this sec tion, the steps p ertinen t to the r eacting channel mo del only ar e explained .The setting up of other mo dels used in conjunc tion with r eacting channel mo dels ar e explained in other sec tions of the U ser's G uide . 1.Enable the r eacting channel mo del. 1673Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Reacting C hannel M odelSetup → Models → Species → Reac ting C hannel M odel Edit... Figur e 15.23: The Reac ting C hannel M odel D ialo g Box When y ou enable the Enable Reac ting C hannel M odel option, the dialo g box will e xpand t o sho w the r elevant inputs (see Figur e 15.23: The R eacting C hannel M odel D ialog Box (p.1674 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1674Modeling S pecies Transp ort and F inite-Rate Chemistr y2.Specify the Numb er of B oundar y Groups . If you ha ve multiple channels , you c an gr oup t ogether channels with c ommon flo w dir ection, mix ture ma terials, inlet c omp ositions , temp erature, pressur e, and mass flo w rate.You will b e requir ed t o pr ovide the inputs f or each b oundar y gr oup . Note If you ha ve multiple tub es, you will need t o define each tub e as a diff erent wall and set up the mo del b y gr ouping the w alls t ogether if the y ha ve the same b oundar y conditions . 3.Enter the numb er of Flow Iterations P er C oupling I teration .This is the numb er of out er flo w iterations for each channel flo w iteration. 4.Optionally change an Under-Relaxa tion F actor.The v alue of the under-r elaxa tion fac tor is used t o up date the hea t flux fr om the r eacting channel. See Equa tion 7.111 in the Theor y Guide . 5.Set the Group Inde x. Note tha t the Group Inde x for the first b oundar y gr oup is set t o 0. The inputs f or each b oundar y gr oup ar e en tered in the Group S ettings and Group Inlet C onditions tabs as fur ther descr ibed. 6.Under the Group S ettings tab , specify the mo del settings and options . (see Figur e 15.24: The R eacting Channel M odel D ialog Box (G roup Inlet C onditions Tab) (p.1676 )). a.In the Channel Walls in G roup selec tion list , selec t the w all b oundar y zones tha t correspond t o the reacting channels . b.Selec t the gr oup ma terial fr om the Material drop-do wn list. You c an cho ose an y mix ture ma terial available in the c ase as a gr oup ma terial. c.Optionally , imp ort a CHEMKIN mechanism using Imp ort CHEMKIN M echanism... butt on. For details see Imp orting a Volumetr ic Kinetic M echanism in CHEMKIN F ormat (p.1624 ). d.To mo del sur face reactions within the channel, enable Surface Reac tions under Model Options group box.The dialo g box will e xpand t o sho w the r elated inputs as sho wn in Figur e 15.23: The R eacting Channel M odel D ialog Box (p.1674 ).These inputs include: •Surface to Volume R atio of the channel gr oup •Surface reaction mechanism of the gr oup (selec ted fr om the Reac tion M echanism drop-do wn list) e.To mo del p orous medium, enable Porous M edium under Model Options group b ox.The dialo g box will e xpand t o sho w porous medium inputs as sho wn in Figur e 15.23: The R eacting C hannel M odel Dialog Box (p.1674 ).These inputs include: •Porosit y of the channel •Visc ous Resistanc e in axial dir ection of the channel •Iner tial Resistanc e in axial dir ection of the channel •Solid ma terial of the p orous medium inside the channel (selec ted fr om the Solid M aterial drop- down list) 1675Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Reacting C hannel M odel7.Under the Group Inlet C onditions tab , specify the inlet c onditions f or the b oundar y gr oup (see Fig- ure 15.24: The R eacting C hannel M odel D ialog Box (G roup Inlet C onditions Tab) (p.1676 )).You c an sp ecify the inlet c ondition par amet ers as c onstan t values . ANSY S Fluen t provides y ou also with the option of r e- defining an y or all of the inlet c ondition par amet ers using user-defined func tions (UDFs). Figur e 15.24: The Reac ting C hannel M odel D ialo g Box (G roup Inlet C onditions Tab) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1676Modeling S pecies Transp ort and F inite-Rate Chemistr ya.Specify the X-,Y-, and Z-comp onen t of the flo w at the inlets of the channels in the cur rent group in the Flow D irection group b ox. Note Since ther e is no sur face or z one t o iden tify the channel inlet or outlet , the inlet flo w direction of the gr oup is used t o det ermine the channel inlet. Therefore, It is v ery imp ortant to sp ecify the flo w dir ection c orrectly. b.Enter the inlet channel Temp erature,Flow R ate and Pressur e in the gr oup . c.Specify the inlet mass fr actions f or each sp ecies in the gr oup in the Species C omp osition group b ox. d.To sp ecify an inlet c ondition using a user-defined func tion (UDF), selec t the User D efined Inlet C on- ditions check b ox and then selec t the appr opriate user-defined func tion fr om the dr op-do wn list. For information ab out sp ecifying and ho oking DEFINE_REA CTING_CHANNEL_BC UDFs , see DEFINE_REACTING_CHANNEL_BC in the Fluent C ustomization Manual . 8.Click the Apply butt on t o sa ve the settings . 9.If you sp ecified mor e than one b oundar y gr oup in st ep 1, change the gr oup ID v alue in Group Inde x integer numb er en try box and r epeat steps 5–7 f or each r emaining b oundar y gr oup . Onc e the r eacting channel mo del is defined , you c an gener ate reports or plots of r eacting channel variables using the Reac ting channel 2D C urves dialo g box (Figur e 15.26: Reacting C hannel 2D C urves Dialog Box (Plot) (p.1679 )).You c an op en the Reac ting channel 2D C urves dialo g box by click ing the Displa y Reac ting C hannel Variables butt on in the Reac ting C hannel M odel dialo g box. For inf orm- ation ab out the plotting of r eacting channel mo del v ariables , see Postpr ocessing f or R eacting C hannel Model C alcula tions (p.1678 ). Mo deling C urvilinear R eac ting C hannels In the r eacting channel mo del, the t wo ends of a channel ar e iden tified as the inlet and the outlet based on the inputs pr ovided f or the inlet flo w dir ection of the gr oup . However, for some sp ecial channel c onfigur ations , such as U-tub es, it is not p ossible t o iden tify the inlet/outlet of the channel based on the inf ormation of the inlet flo w dir ection. For such c ases , an additional input is r equir ed t o differentiate between the end p oints of the channel as inlet or outlet. The additional input is t o pr ovide the c entroid c oordina tes of the inlet of the U shap ed channel. Therefore, for U-tub e configur ations , after setting up the r eacting channel mo del f ollowing the ear lier st eps in this sec tion, it is r equir ed t o use the f ollowing t ext user in terface commands t o set the inlet and outlets c orrectly: /define/models/species> reacting-channel-model-options Are any of the channels a U-tube configuration? [no] yes Is wall tube1 a U-tube configuration? [no] yes Enter the coordinates of the center of the inlet for wall tube1 X coordinate [0] 0.01 Y coordinate [0] 0 Z coordinate [0] 0 Where tube1 is a r eacting channel w all ha ving a U shap e.You will b e ask ed the same questions f or each of the e xisting r eacting channel w alls. 1677Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Reacting C hannel M odel15.6.3. Boundar y Conditions f or C hannel Walls In the ANSY S Fluen t wall b oundar y conditions dialo g box, the w all sur faces tha t you selec ted as channel w alls in the Reac ting C hannel M odel dialo g box will ha ve zero hea t flux b oundar y conditions , which ar e disabled as sho wn in Wall Sur face Reactions and C hemic al Vapor D eposition (p.1654 )). Figur e 15.25: The Wall B oundar y Condition D ialo g Box for the Reac ting C hannel M odel The hea t flux a t the channel w alls is c alcula ted in ternally thr ough the c oupling of the r eacting channel model with the out er flo w as descr ibed in Reacting C hannel M odel in the Theor y Guide . For all other wall sur faces, which ar e not channel w alls, all b oundar y conditions as descr ibed in Wall B oundar y Conditions (p.971) are applic able . 15.6.4. Postpr ocessing f or Reac ting C hannel M odel C alcula tions ANSY S Fluen t provides p ostpr ocessing options f or plotting and r eporting channel v ariables using the Reac ting C hannel 2D C urves dialo g box tha t op ens b y click ing the Displa y Reac ting C hannel Vari- ables butt on in the Reac ting C hannel M odel dialo g box.You c an gener ate X-Y plots or r eports of the f ollowing r eacting channel v ariables: •Bulk mean t emp erature of the channel •Wall temp erature of the channel •Nusselt N umb er (f or the channel w all on the channel side) •Wall hea t flux thr ough the channel w alls •Velocity inside the channel •Densit y of the channel Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1678Modeling S pecies Transp ort and F inite-Rate Chemistr y•Mass fr action of the sp ecies inside the channel •The sur face coverage and the dep osition r ate of the sur face sp ecies . The st eps f or gener ating the plots/r eports ar e as f ollows: 1. Selec t either Plot Reac ting C hannel Variables or Rep ort Reac ting C hannel Outlet A verage . The Reac ting C hannel 2D C urves dialo g box displa ys either the Variable N ame drop-do wn list for selec ting a single sp ecies f or X-Y plot gener ation, or the Variable N ames selec tion list f or se- lecting multiple sp ecies f or report gener ation as sho wn in Figur e 15.26: Reacting C hannel 2D Curves D ialog Box (Plot) (p.1679 ) and Figur e 15.27: Reacting C hannel 2D C urves D ialog Box (R e- port) (p.1680 ). Figur e 15.26: Reac ting C hannel 2D C urves D ialo g Box (P lot) 1679Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Reacting C hannel M odelFigur e 15.27: Reac ting C hannel 2D C urves D ialo g Box (Rep ort) 2. Specify whether y ou w ant to wr ite the plot da ta to a file b y using the Write To File check b ox. 3. If mor e than one b oundar y gr oup is defined f or reacting channel mo del, specify the gr oup ID in the Group Inde x integer numb er en try box. 4. The Variable N ame drop-do wn/ Variable N ames selec tion list c ontains r eacting channel v ariables of the sp ecified b oundar y gr oup . Selec t the r eacting channel v ariable(s) fr om the list. 5. Selec t the w all sur face(s) fr om the Wall S urfaces selec tion list on which the plot/r eport will b e gener ated (at least one w all sur face must b e selec ted). 6. Click one of the f ollowing as applic able: •Plot to view X-Y plot in the gr aphics windo w •Print to view r eport in the c onsole windo w •Write... to sa ve to file 15.7. Reac tor N etwork M odel Information ab out using the R eactor N etwork mo del is pr esen ted in the f ollowing subsec tions . 15.7.1. Overview and Limita tions of the R eactor N etwork Model 15.7.2. Solving R eactor N etworks 15.7.3. Postpr ocessing R eactor N etwork Calcula tions Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1680Modeling S pecies Transp ort and F inite-Rate Chemistr yFor mor e inf ormation ab out the theor etical back ground , see Reactor N etwork Model in the Fluent Theor y Guide . 15.7.1. Overview and Limita tions of the Reac tor N etwork M odel The R eactor N etwork mo del allo ws rapid solution of c ombust ors using detailed chemic al kinetic mechanisms .This sp eed is achie ved b y first p erforming a F luen t CFD simula tion with a fast chemistr y model, such as a N on-P remix ed, Partially-P remix ed, or E ddy-Dissipa tion mo del, and then using the Reactor N etwork mo del t o solv e with a detailed k inetic mechanism. The R eactor N etwork mo del ag- glomer ates c ells fr om the CFD solution in to a user-sp ecified small numb er of r eactors and c omput es detailed chemistr y on this r eactor net work. Since the chemic al kinetics is dec oupled fr om the flo w, reactor net work simula tions ar e applic able t o steady simula tions wher e the chemic al kinetics do es not aff ect the flo w signific antly, such as p ollutan t formation. Inher ently unst eady simula tions , such as ignition and global e xtinc tion, cannot b e mo deled with r eactor net works. Note tha t the R eactor N etwork mo del c an b e used f or unst eady simula tions of statistic ally st eady flo ws, such as LES, wher e the time-a veraged flo w and sp ecies fields ar e used t o constr uct the r eactor net work. 15.7.2. Solving Reac tor N etworks The st eps and pr ocedur e for setting up and solving a R eactor N etwork mo del ar e outlined b elow. 1.Enable the R eactor N etwork mo del. Setup → Models → Species → Reac tor N etwork Edit... Imp ortant Note tha t this mo del is only a vailable when one of the r eacting sp ecies mo dels is enabled . When y ou selec t the Reac tor N etwork M odel option, the dialo g box expands t o sho w the r elevant modeling c ontrols (see Figur e 15.28: Reactor N etwork Dialog Box (Steady-State Flow) (p.1682 )). 1681Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Reactor N etwork ModelFigur e 15.28: Reac tor N etwork D ialo g Box (S tead y-State Flow) 2.If a detailed chemic al mechanism has alr eady been imp orted, selec t the mix ture ma terial fr om the Detailed Mechanism M aterial N ame drop-do wn list. Other wise imp ort a mechanism in CHEMKIN f ormat by click ing Imp ort CHEMKIN M echanism... .The mechanism files ar e imp orted in to your c ase using the Imp ort CHEMKIN F ormat Mechanism dialo g box as descr ibed in Specifying a C hemic al M echanism F ile for Flamelet G ener ation (p.1697 ). 3.Set the Numb er of Reac tors in the r eactor net work.The default v alue of 50 is a go od star ting v alue , but it can b e incr eased f or gr eater accur acy. 4.Specify whether or not the t emp erature is c alcula ted fr om the equa tion of sta te by selec ting or clear ing the Solve Temp erature check b ox. By default , this option is selec ted, and ANSY S Fluen t will det ermine the t emp eratures in the r eactor net work. 5.Onc e cells ar e agglomer ated and a r eactor-net work solution is c alcula ted, you c an selec t the Use C urrent Reac tor N etwork option t o perform fur ther r eactor net work simula tions with the e xisting net work of connec ted r eactors.This option c an b e used t o continue it erations fr om the pr evious r eactor- net work solution if additional c onvergenc e is desir ed.The option also allo ws you t o change the chemic al mechanism or sp ecies b oundar y conditions t o gener ate a new solution on the cur rent reactor net work. 6.(for tr ansien t analy sis with the Data S ampling F or Time S tatistics option selec ted in the Run C alcula tion task page only) S pecify whether or not y ou w ant to use the time-a veraged c omp osition fields t o agglom- Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1682Modeling S pecies Transp ort and F inite-Rate Chemistr yerate the r eactors and time-a veraged v elocity fields t o calcula te the r eactor mass flux ma trix (inst ead of the instan taneous fields) b y selec ting or clear ing the Use Time A veraged F ields option. Note The Use Time A veraged F ields option should b e used f or unst eady simula tions (f or example , LES) of sta tistic ally sta tionar y combust ors. 7.If nec essar y, specify cust om-field func tions and adjust the default solv er settings using the Expert Options control.When Expert Options is selec ted, the Reac tor N etwork dialo g box expands t o reveal the f ollowing advanced options: Figur e 15.29: Reac tor N etwork D ialo g Box - E xpert Options ODE Rela tive Error Toler anc e,ODE A bsolut e Error Toler anc e The default v alues f or the ODE r elative and absolut e error toler ances ar e 1e-05 and 1e-12, respectively. If the ODE solv er fails t o converge, it is of ten helpful t o lower the ODE Rela tive Error Toler anc e and the ODE A bsolut e Error Toler anc e. 1683Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Reactor N etwork ModelReac tor N etwork Convergenc e Toler anc e The default v alue f or the r eactor net work convergenc e toler ance is 1e-08. Residuals should b e well converged a t the default t oler ance. Higher t oler ances ma y be acc eptable f or engineer ing accur acy. Solver The default segr egated solv er typic ally c onverges fast er than the c oupled solv er. However, when using the segr egated solv er, residuals ma y stall ab ove an acc eptable t oler ance. In this c ase, the c oupled solv er should b e used . Maximum N umb er of I terations (segr ega ted solv er) If residuals ar e still decr easing and b etter convergenc e is desir ed, incr ease the maximum numb er of iterations . If residuals ar e stalled and a quick er exit fr om the solv er is desir ed, decr ease the maximum numb er of it erations . Maximum In tegration Time (c oupled solv er) The ODE solv er termina tes the c alcula tion a t this time if r esiduals fail t o converge. Use C ustom F ield F unc tions t o D efine Reac tor Z ones When selec ted, this option allo ws you t o use cust om field func tions ( Custom F ield F unctions (p.3038 )) as comp osition v ariables t o create the r eactor v olumes . ANSY S Fluen t clust ers CFD c ells tha t ha ve similar c omp ositions using the f ollowing default c omp osition v ariables: •temp erature and mix ture fraction f or N on-P remix ed and P artially-P remix ed c ases •temp erature and mass fr actions of N2 and H2O for S pecies Transp ort cases You c an o verride these default c omp osition v ariables b y selec ting Use C ustom F ield F unc tions t o Define Reac tor Z ones and then selec ting up t o four cust om field func tions fr om the Custom F ield Func tions selec tion list. ANSY S Fluen t will gr oup CFD c ells tha t are close in these cust om field func tion comp osition v ariables . In the e xample sho wn in Figur e 15.29: Reactor N etwork Dialog Box - Exp ert Options (p.1683 ), cells with similar turbulen t kinetic ener gy, x coordina te, and y c oordina te will b e ag- glomer ated t o form the r eactor net work. 8.Click Calcula te Reac tor N etwork to obtain a flo w solution. As the c alcula tion is pr ogressing , ANSY S Fluen t prints the r eactor net work residuals f or each it eration in the c onsole . Note The r eactor net work solution should c onverge with the default settings . However, if the model fails t o converge with sufficien t accur acy, you c an adjust the default r eactor network solv er settings b y using the Expert Options control. 15.7.3. Postpr ocessing Reac tor N etwork Calcula tions ANSY S Fluen t provides additional p ostpr ocessing options f or reactor net work calcula tions .The f ollowing reactor net work variables ar e available f or gener ating gr aphic al plots: •Reac tor N et Z one ID •Reac tor N et Temp erature Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1684Modeling S pecies Transp ort and F inite-Rate Chemistr y•Reac tor N et M ass fr action of sp ecies-n These v ariables will app ear under the Reac tor N etwork… postpr ocessing c ategor y of the v ariable selec tion dr op-do wn lists . 1685Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Reactor N etwork ModelRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1686Chapt er 16: Modeling N on-P remix ed C ombustion This chapt er pr ovides details ab out the non-pr emix ed c ombustion mo deling c apabilities in ANSY S Fluen t. The non-pr emix ed c ombustion mo del is pr esen ted in the f ollowing sec tions: 16.1. Steps in U sing the N on-P remix ed M odel 16.2. Setting U p the E quilibr ium C hemistr y Model 16.3. Setting U p the S teady and U nsteady Diffusion F lamelet M odels 16.4. Defining the S tream C omp ositions 16.5. Setting U p Control Paramet ers 16.6. Calcula ting the F lamelets 16.7. Calcula ting the L ook-U p Tables 16.8. Standar d Files f or D iffusion F lamelet M odeling 16.9. Setting U p the Iner t Model 16.10. Defining N on-P remix ed B oundar y Conditions 16.11. Defining N on-P remix ed P hysical Properties 16.12. Solution S trategies f or N on-P remix ed M odeling 16.13. Postpr ocessing the N on-P remix ed M odel R esults For theor etical back ground on the non-pr emix ed c ombustion mo del, see Non-P remix ed C ombustion in the Theor y Guide . 16.1. Steps in U sing the N on-P remix ed M odel A descr iption of the inputs f or the non-pr emix ed mo del is pr ovided in the sec tions tha t follow. 16.1.1. Preliminar ies 16.1.2. Defining the P roblem Type 16.1.3. Overview of the P roblem S etup P rocedur e 16.1.1. Preliminar ies Before tur ning on the non-pr emix ed c ombustion mo del, you must enable turbulenc e calcula tions in the Viscous M odel D ialog Box (p.3253 ). Setup → Models → Visc ous Edit... If your mo del is non-adiaba tic, you should also enable hea t transf er (and r adia tion, if requir ed). Setup → Models → Energy ON Setup → Models → Radia tion Edit... Figur e 8.7: Reacting S ystems R equir ing N on-A diaba tic N on-P remix ed M odel A pproach in the Theor y Guide illustr ates the t ypes of pr oblems tha t must b e treated as non-adiaba tic. 1687Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.16.1.2. Defining the P roblem Type Your first task is t o define the t ype of r eaction sy stem and r eaction mo del tha t you in tend t o use .This includes selec tion of the f ollowing options: •Non-pr emix ed or par tially pr emix ed mo del option (see Modeling P artially P remix ed C ombustion (p.1759 )). •Equilibr ium chemistr y mo del, steady diffusion flamelet mo del, unst eady diffusion flamelet mo del, or diesel unst eady flamelet. •Adiaba tic or non-adiaba tic mo deling options (see Non-A diaba tic Ex tensions of the N on-P remix ed M odel in the Theor y Guide ). •Addition of a sec ondar y str eam (equilibr ium mo del only). •Empir ically defined fuel and/or sec ondar y str eam c omp osition (equilibr ium mo del only). You c an mak e these mo del selec tions using the Species M odel dialo g box (Figur e 16.6: The S pecies Model D ialog Box (C hemistr y Tab) (p.1692 )). Setup → Models → Species Edit... 16.1.3. Overview of the P roblem S etup P rocedur e For a single-mix ture-fraction pr oblem, you will p erform the f ollowing st eps: 1.Choose the chemic al descr iption of the sy stem: chemic al equilibr ium, steady diffusion flamelet , unst eady diffusion flamelet , or diesel unst eady flamelet ( Figur e 16.1: Defining E quilibr ium C hemistr y (p.1688 )). 2.Indic ate whether the pr oblem is adiaba tic or non-adiaba tic. Figur e 16.1: Defining E quilibr ium C hemistr y Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1688Modeling N on-P remix ed C ombustion3.(steady diffusion flamelet mo del only) Imp ort a flamelet file or appr opriate CHEMKIN mechanism file if gener ating flamelets ( Figur e 16.2: Defining S teady Diffusion F lamelet C hemistr y (p.1689 )). Figur e 16.2: Defining S tead y D iffusion F lamelet C hemistr y 4.Define the chemic al boundar y sp ecies t o be consider ed f or the str eams in the r eacting sy stem mo del. Note tha t this st ep is not r elevant in the c ase of flamelet imp ort (Figur e 16.3: Defining C hemic al Boundar y Species (p.1689 )). For mor e inf ormation, see Defining the S tream C omp ositions (p.1702 ). Figur e 16.3: Defining C hemic al B oundar y Species 1689Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Steps in U sing the N on-P remix ed M odel5.(steady diffusion flamelet mo del only) I f you ar e gener ating flamelets , comput e the flamelet sta te relation- ships of sp ecies mass fr actions , densit y, and t emp erature as a func tion of mix ture fraction and sc alar dis- sipa tion ( Figur e 16.4: Calcula ting S teady Diffusion F lamelets (p.1690 )). Figur e 16.4: Calcula ting S tead y D iffusion F lamelets 6.Comput e the final chemistr y look-up table , containing mean v alues of sp ecies fr actions , densit y, and temp erature as a func tion of mean mix ture fraction, mix ture fraction v arianc e, and p ossibly en thalp y and scalar dissipa tion. The c ontents of this lo ok-up table will r eflec t your pr eceding inputs descr ibing the turbulen t reacting sy stem ( Figur e 16.5: Calcula ting the C hemistr y Look-U p Table (p.1691 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1690Modeling N on-P remix ed C ombustionFigur e 16.5: Calcula ting the C hemistr y Look-U p Table The lo ok-up table is the st ored r esult of the in tegration of Equa tion 8.17 (or Equa tion 8.25 ) and Equa- tion 8.19 (in the Theor y Guide ).The lo ok-up table will b e used in ANSY S Fluen t to det ermine mean species mass fr actions , densit y, and t emp erature from the v alues of mean mix ture fraction ( ), mix ture fraction v arianc e ( ), and p ossibly mean en thalp y ( ) and mean sc alar dissipa tion ( ) as the y are comput ed dur ing the ANSY S Fluen t calcula tion of the r eacting flo w. See Look-U p Tables f or A diaba tic Systems and Figur e 8.8: Visual R epresen tation of a L ook-U p Table f or the Sc alar (M ean Value of M ass Fractions , Densit y, or Temp erature) as a F unction of M ean M ixture Fraction and M ixture Fraction Varianc e in A diaba tic S ingle-M ixture-Fraction S ystems and Figur e 8.10: Visual R epresen tation of a L ook-U p Table for the Sc alar as a F unction of M ean M ixture Fraction and M ixture Fraction Varianc e and N ormaliz ed Heat Loss/G ain in N on-A diaba tic S ingle-M ixture-Fraction S ystems in the Theor y Guide . For a pr oblem tha t includes a sec ondar y str eam (and , ther efore, a sec ond mix ture fraction), you will perform the first t wo steps list ed ab ove for the single-mix ture-fraction appr oach and then pr epar e a look-up table of instan taneous pr operties using Equa tion 8.13 or Equa tion 8.15 in the Theor y Guide . 16.2. Setting U p the E quilibr ium C hemistr y M odel In the equilibr ium chemistr y mo del, the c oncentrations of sp ecies of in terest ar e det ermined fr om the mixture fraction using the assumption of chemic al equilibr ium (see Non-P remix ed C ombustion and Mixture Fraction Theor y in the Theor y Guide ).With this mo del, you c an include the eff ects of in terme- diate sp ecies and disso ciation r eactions , producing mor e realistic pr edic tions of flame t emp eratures than the E ddy-Dissipa tion mo del. When y ou cho ose the equilibr ium chemistr y option, you will ha ve the opp ortunit y to use the r ich flammabilit y limit (RFL) option. To enable the equilibr ium chemistr y mo del 1.Selec t Non-P remix ed C ombustion in the Species M odel dialo g box. 2.Selec t Chemic al E quilibr ium in the Chemistr y tab of the Species M odel dialo g box. 1691Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the E quilibr ium C hemistr y ModelFigur e 16.6: The S pecies M odel D ialo g Box (C hemistr y Tab) For additional inf ormation, see the f ollowing sec tions: 16.2.1. Choosing A diaba tic or N on-A diaba tic Options 16.2.2. Specifying the Op erating P ressur e for the S ystem 16.2.3. Enabling a S econdar y Inlet S tream 16.2.4. Choosing t o Define the F uel S tream(s) Empir ically 16.2.5. Enabling the R ich F lammabilit y Limit (RFL) Option 16.2.1. Choosing A diaba tic or N on-A diaba tic Options You should use the non-adiaba tic mo deling option if y our pr oblem definition in ANSY S Fluen t will in- clude one or mor e of the f ollowing: •radia tion or w all hea t transf er •multiple fuel inlets a t diff erent temp eratures •multiple o xidan t inlets a t diff erent temp eratures •liquid fuel, coal par ticles , and/or hea t transf er to iner t par ticles Note tha t the adiaba tic mo del is a simpler mo del in volving a t wo-dimensional lo ok-up table in which scalars dep end only on and (or on and ). If your mo del is defined as adiaba tic, you will not need t o solv e the ener gy equa tion in ANSY S Fluen t and the sy stem t emp erature will b e det ermined directly fr om the mix ture fraction and the fuel and o xidan t inlet t emp eratures.The non-adiaba tic c ase will b e mor e comple x and mor e time-c onsuming t o comput e, requir ing the gener ation of thr ee-dimen- sional lo ok-up tables . However, the non-adiaba tic mo del option allo ws you t o include the t ypes of reacting sy stems descr ibed ab ove. Selec t Adiaba tic or Non-A diaba tic in the Chemistr y tab of the Species M odel dialo g box. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1692Modeling N on-P remix ed C ombustion16.2.2. Specifying the Op erating P ressur e for the S ystem The sy stem Operating P ressur e is used t o calcula te densit y using the ideal gas la w. For non-adiaba tic simula tions , the Compr essibilit y Effects under PDF Options can b e enabled t o acc oun t for c ases wher e substan tial pr essur e changes o ccur in time and/or spac e. In such c ases it is assumed tha t the species mass fr actions do not change with pr essur e, and the densit y is c alcula ted as (16.1) wher e is the densit y at the sp ecified Operating P ressur e ( ), and is the lo cal mean pr essur e in an ANSY S Fluen t cell. When the Compr essibilit y Effects option is enabled , the flo w op erating pr essur e (set in the Operating Conditions dialo g box) can diff er fr om the N on-P remix ed mo del op erating pr essur e.To distinguish this diff erence, the Operating P ressur e name tag in the Species M odel dialo g box changes t o Equi- libr ium Op erating P ressur e when the c ompr essibilit y eff ects option is enabled . See Solution S trategies f or N on-P remix ed M odeling (p.1741 ) for details ab out enabling c ompr essibilit y effects. 16.2.3. Enabling a S econdar y Inlet S tream If you ar e mo deling a sy stem c onsisting of a single fuel and a single o xidiz er str eam, you do not need to enable a sec ondar y str eam in y our PDF c alcula tion. As discussed in Definition of the M ixture Fraction in the Theor y Guide , a sec ondar y str eam should b e enabled if y our PDF r eaction mo del will include any of the f ollowing: •two dissimilar gaseous fuel str eams –In these simula tions , the fuel str eam defines one of the fuels and the sec ondar y str eam defines the sec ond fuel. •mixed fuel sy stems of dissimilar gaseous and liquid fuel –In these simula tions , the fuel str eam defines the gaseous fuel and the sec ondar y str eam defines the liquid fuel (or vic e versa). •mixed fuel sy stems of dissimilar gaseous and c oal fuels –In these simula tions , you c an use the fuel str eam or the sec ondar y str eam t o define either the c oal or the gaseous fuel. See Modeling C oal C ombustion U sing the N on-P remix ed M odel (p.1706 ) regar ding c oal combustion simula tions with the non-pr emix ed c ombustion mo del. •mixed fuel sy stems of c oal and liquid fuel –In these simula tions , you c an use the fuel str eam or the sec ondar y str eam t o define either the c oal or the liquid fuel. See Modeling C oal C ombustion U sing the N on-P remix ed M odel (p.1706 ) regar ding c oal combustion simula tions with the non-pr emix ed c ombustion mo del. •coal c ombustion –Coal c ombustion c an b e mor e accur ately mo deled b y using a sec ondar y str eam t o track the distinc t volatile and char off-gases .The fuel str eam must define the char and the sec ondar y str eam must define 1693Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the E quilibr ium C hemistr y Modelthe v olatile c omp onen ts of the c oal. See Modeling C oal C ombustion U sing the N on-P remix ed M odel (p.1706 ) regar ding c oal c ombustion simula tions with the non-pr emix ed c ombustion mo del. •a single fuel with t wo dissimilar o xidiz er str eams –In these simula tions , the fuel str eam defines the fuel, the o xidiz er str eam defines one of the o xidiz ers, and the sec ondar y str eam defines the sec ond o xidiz er. To include a sec ondar y str eam in y our mo del, turn on the Secondar y Stream option under Stream Options in the Chemistr y tab . Imp ortant Using a sec ondar y str eam c an substan tially incr ease the c alcula tion time f or y our simula tion sinc e the multi-dimensional PDF in tegrations ar e performed a t run time . Alternatively, ANSY S Fluen t can p erform a full tabula tion of the PDF in tegrations , as detailed in Full Tabula tion of the Two-M ixture-Fraction M odel (p.1727 ). When the sec ondar y str eam is pr esen t, only instan taneous sp ecies mass fr action, temp erature and mixture pr operties ar e stored inside PDF table .The pr obabilit y densit y func tion (PDF) c alcula tes a veraged species mass fr action and mix ture pr operties a t the r un time . After a PDF table has b een gener ated or read in to ANSY S Fluen t, you c an selec t the shap e of the assumed PDF fr om the Probabilit y D ensit y Func tion drop-do wn list ( PDF Options group b ox): •double delta : as giv en b y Equa tion 8.21 in the Fluent Theor y Guide . •beta: as giv en b y Equa tion 8.22 in the Fluent Theor y Guide . 16.2.4. Choosing t o Define the F uel S tream(s) E mpir ically The empir ical fuel option pr ovides an alt ernative metho d for defining the c omp osition of the fuel or secondar y str eam when the individual sp ecies c omp onen ts of the fuel ar e unk nown. That is, you will define the elemen tal fr action not the individual sp ecies .When this option is disabled , you will define the chemic al sp ecies tha t are pr esen t in each str eam and the mass or mole fr action of each sp ecies , as descr ibed in Defining the S tream C omp ositions (p.1702 ).The option f or defining an empir ical fuel stream is par ticular ly useful f or c oal c ombustion simula tions (see Modeling C oal C ombustion U sing the N on-P remix ed M odel (p.1706 )) or f or simula tions in volving other c omple x hydrocarbon mix tures. To define a fuel or sec ondar y str eam empir ically 1.Turn on the Empir ical F uel S tream option under Stream Options in the Chemistr y tab of the Species Model dialo g box. If you ha ve a sec ondar y str eam, enable the Empir ical S econdar y Stream option, or both as appr opriate. 2.Specify the appr opriate lower hea ting v alue (f or e xample Empir ical F uel L ower C alor ic Value ,Empir ical Secondar y Lower C alor ic Value ), specific hea t (Empir ical F uel S pecific H eat,Empir ical S econdar y Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1694Modeling N on-P remix ed C ombustionSpecific H eat), and molecular w eigh t (Empir ical F uel M olecular Weigh t,Empir ical S econdar y M olecular Weigh t) for each empir ically defined str eam. Imp ortant The empir ical definition option is a vailable only with the full equilibr ium chemistr y mo del. It cannot b e used with the r ich flammabilit y limit (RFL) option or the st eady and unst eady diffusion flamelet mo dels , sinc e equilibr ium c alcula tions ar e requir ed f or the det ermina tion of the fuel c omp osition. Imp ortant The empir ical fuel and sec ondar y molecular w eigh ts ar e only r equir ed if y our empir ical streams ar e en tering the domain via an inlet b oundar y, or if y ou ar e using the par tially premix ed mo del. If you ar e using the non-pr emix ed mo del and the empir ically defined streams or igina te from the disp ersed phase (f or e xample , if y ou ar e mo deling c oal or liquid fuel c ombustion) the molecular w eigh ts ar e not r equir ed f or the c omputa tion. 16.2.5. Enabling the R ich F lammabilit y Limit (RFL) Option You c an define a r ich limit on the mix ture fraction when the equilibr ium chemistr y option is used . Input of the r ich limit is acc omplished b y sp ecifying a v alue of the Rich F lammabilit y Limit for the appr o- priate Fuel S tream ,Secondar y Stream , or b oth. You will not b e allo wed t o sp ecify the Rich F lammab- ility Limit if y ou ha ve used the empir ical definition option f or fuel c omp osition. ANSY S Fluen t will c omput e the c omp osition a t the r ich limit using equilibr ium. For mix ture fraction values ab ove this limit , ANSY S Fluen t will susp end the equilibr ium chemistr y calcula tion and will comput e the c omp osition based on mixing , but not bur ning , of the fuel with the c omp osition a t the rich limit. A v alue of 1.0 f or the r ich limit implies tha t equilibr ium c alcula tions will b e performed o ver the full r ange of mix ture fraction. When y ou use a r ich limit tha t is less than 1.0, equilibr ium c alcula tions are susp ended whene ver , , or exceeds the limit. This RFL mo del is of ten mor e accur ate than the assumption of chemic al equilibr ium f or rich mix tures, and also a voids c omple x equilibr ium calcula tions , speeding up the pr epar ation of the lo ok-up tables . An RFL v alue of appr oxima tely t wice the st oichiometr ic mix ture fraction is appr opriate. For the Secondar y Stream , the r ich flammabilit y limit c ontrols the equilibr ium c alcula tion f or the secondar y mix ture fraction. If your sec ondar y str eam is not a fuel, you should use an RFL v alue of 1. A value of 1.0 f or the r ich limit implies tha t equilibr ium c alcula tions will b e performed o ver the full range of mix ture fraction. When y ou input a r ich limit tha t is less than 1.0, equilibr ium c alcula tions ar e susp ended whene ver exceeds the limit. (Note tha t it is the sec ondar y mix ture fraction and not the par tial fr action tha t is used her e.) Imp ortant Experimen tal studies and r eview s [12] (p.4005 ),[116] (p.4011 ) have sho wn tha t although the fuel-lean flame r egion appr oxima tes ther modynamic equilibr ium, non-equilibr ium k inetics will pr evail under fuel-r ich c onditions .Therefore, for non-empir ically defined fuels , the RFL model is str ongly r ecommended . 1695Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the E quilibr ium C hemistr y Model16.3. Setting U p the S tead y and U nstead y Diffusion F lamelet M odels To enable the diffusion flamelet mo dels 1.Selec t Non-P remix ed C ombustion in the Species M odel dialo g box. 2.Selec t Stead y Diffusion F lamelet or Unstead y Diffusion F lamelet in the Chemistr y tab of the Species Model dialo g box. See Using the U nsteady Diffusion F lamelet M odel (p.1697 ). Figur e 16.7: The C hemistr y Tab f or the U nstead y D iffusion F lamelet M odel For additional inf ormation, see the f ollowing sec tions: 16.3.1. Choosing A diaba tic or N on-A diaba tic Options 16.3.2. Specifying the Op erating P ressur e for the S ystem 16.3.3. Specifying a C hemic al M echanism F ile for Flamelet G ener ation 16.3.4. Imp orting a F lamelet 16.3.5. Using the U nsteady Diffusion F lamelet M odel 16.3.6. Using the D iesel U nsteady Laminar F lamelet M odel 16.3.7. Resetting D iesel U nsteady Flamelets 16.3.1. Choosing A diaba tic or N on-A diaba tic Options Selec t Adiaba tic or Non-A diaba tic in the Chemistr y tab of the Species M odel dialo g box. See the discussion in Choosing A diaba tic or N on-A diaba tic Options (p.1692 ) about the t wo options . 16.3.2. Specifying the Op erating P ressur e for the S ystem The sy stem Operating P ressur e is used t o calcula te densit y using the ideal gas la w.When the Com- pressibilit y Effects option is enabled , the name Operating P ressur e is changed t o Equilibr ium Op- erating P ressur e sinc e the non-pr emix ed c ombustion mo del op erating pr essur e can diff er fr om the flow op erating pr essur e.Specifying the Op erating P ressur e for the S ystem (p.1693 ) provides mor e in- formation ab out this v alue . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1696Modeling N on-P remix ed C ombustionYou c an use the st eady or unst eady diffusion flamelet mo del f or reactions in liquid sy stems .To do so , enable Liquid M icro-M ixing under PDF Options .The Liquid M icro-M ixing option is discussed in detail in Liquid R eactions in the Theor y Guide . 16.3.3. Specifying a C hemic al M echanism F ile f or F lamelet G ener ation If you ar e gener ating a flamelet file y ourself , you will need t o read in the chemic al kinetic mechanism and ther modynamic da ta.The mechanism and ther modynamic da ta must b e in CHEMKIN f ormat [59] (p.4008 ). To read in a CHEMKIN mechanism, selec t the Create Flamelet option in the Chemistr y tab of the Species M odel dialo g box and click the Imp ort CHEMKIN M echanism... butt on. Using the Imp ort CHEMKIN F ormat Mechanism dialo g box, imp ort the gas-phase files in to ANSY S Fluen t as descr ibed in Imp orting a Volumetr ic Kinetic M echanism in CHEMKIN F ormat (p.1624 ). Note tha t for flamelet gen- eration, only a gas-phase k inetic mechanism and a ther modynamic da tabase ar e requir ed. Note tha t the imp ort is limit ed t o mechanisms with 700 or f ewer sp ecies . 16.3.4. Imp orting a F lamelet To imp ort an e xisting flamelet file 1.Selec t the Imp ort Flamelet option in the Chemistr y tab of the Species M odel dialo g box. 2.(steady diffusion flamelet only) S elec t either Standar d or CFX-RIF format under File Type. 3.Click the Imp ort Flamelet F ile... butt on. In The S elec t File D ialog Box (p.569), selec t the file (f or a single flamelet) or files (f or multiple flamelets) t o be read in t o ANSY S Fluen t. After y ou ha ve complet ed this st ep, you c an sk ip ahead t o the Table tab of the Species M odel dialo g box (see Calcula ting the L ook-U p Tables (p.1723 )). 16.3.5. Using the U nstead y Diffusion F lamelet M odel The unst eady diffusion flamelet mo del c an only b e enabled fr om a v alid st eady-sta te, steady diffusion flamelet solution. When enabled , the unst eady diffusion flamelet mo del will change this c ase t o unst eady and p ostpr ocess mar ker pr obabilit y equa tions on the fr ozen flo w field .You should henc e ensur e tha t the star ting st eady-sta te, steady diffusion flamelet solution is fully c onverged . When the Unstead y D iffusion F lamelet is enabled in the Chemistr y tab , the Imp ort Flamelet F ile for Restar t... butt on app ears in the dialo g box, allo wing y ou t o run the simula tion fr om a pr eviously saved c ase, data and unst eady flamelet file . The U nsteady Diffusion F lamelet M odel r equir es four user inputs in the Flamelet tab: •The Numb er of G rid P oints in F lamelet . •The Mixture Fraction L ower Limit f or Initial P robabilit y.The initial c ondition of the mar ker pr obabilit y field is unit y for all mean mix ture fractions ab ove the Mixture Fraction L ower Limit f or Initial P robabilit y, and z ero for mean mix ture fractions b elow it. Note tha t this should b e sp ecified t o be gr eater than the stoichiometr ic mix ture fraction. 1697Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the S teady and U nsteady Diffusion F lamelet M odels•Maximum Sc alar D issipa tion . Flamelets ma y extinguish a t high sc alar dissipa tions b ecause diffusion in the flamelet o verwhelms r eaction. It is p ossible t o ha ve unr ealistic ally high mo deled sc alar dissipa tion in the 2D or 3D ANSY S Fluen t simula tions , which gets tr ansf erred t o the 1D unst eady flamelet. In or der t o avoid e xcessiv e diffusion in the 1D unst eady flamelet , the instan taneous sc alar dissipa tion in the 1D flamelet is limit ed t o the sp ecified Maximum Sc alar D issipa tion . •Cour ant Numb er.The time st ep f or the unst eady pr obabilit y mar ker equa tion is c alcula ted aut oma tically by ANSY S Fluen t based on the Cour ant Numb er. Larger v alues imply f ewer time st eps t o convect/diffuse the mar ker pr obabilit y out of the domain, but also r esults in a lar ger numer ical er ror.The Cour ant Numb er should b e small enough so tha t the unst eady flamelet mean mass fr actions ar e unchanged with an y smaller Cour ant Numb er.The default v alue of 1 should b e sufficien t for most applic ations . •Numb er of F lamelets .The numb er of unst eady laminar flamelets tha t ANSY S Fluen t will gener ate dur ing the r un.The mar ker pr obabilit y equa tion Equa tion 8.57 in the Fluent Theor y Guide will b e solv ed f or each flamelet. When these inputs ha ve been set , click ing the Initializ e Unstead y Flamelet P robabilit y butt on initial- izes the mar ker pr obabilit y equa tion f or each flamelet , aut oma tically enabling the Unstead y solv er, while disabling all equa tions e xcept the Unstead y Flamelet P robabilit y equa tion in the Solution Controls task page .This initializa tion in the Flamelet tab also sets the Time S tep S ize in the Run Calcula tion task page . Imp ortant •Do not initializ e your solution fr om the tr ee or the Solution Initializa tion task page . Note tha t you ar e postpr ocessing a pr obabilit y field on the fr ozen st eady-sta te flo w field , and b y click ing the Initializ e Unstead y Flamelet P robabilit y butt on, you ha ve alr eady initializ ed the pr obab- ility mar ker field . •If you disable the Unstead y Diffusion F lamelet mo del and y ou w ant to revert to solving a steady diffusion flamelet simula tion, mak e sur e you enable Stead y (either in the Gener al task page or in the tr ee fr om the Setup /Gener al/ Analy sis Type tree it em) and enable all the equa tions (in the Solution C ontrols task page or in the tr ee fr om the Solution /Solution C ontrols tree it em). 16.3.6. Using the D iesel U nstead y Laminar F lamelet M odel The diesel unst eady laminar flamelet mo del c an only b e enabled when c onditions f or c ompr ession- ignition ar e met: •The Transien t solv er is selec ted in the Gener al task page (or in the tr ee fr om the Setup /Gener al/ Analy sis Type). •The In-C ylinder dynamic mesh is enabled . •The D iscrete Phase mo del option Interaction with C ontinuous P hase is selec ted. The basic st eps f or setting the diesel unst eady laminar flamelet mo dels ar e as f ollows. 1.In the Chemistr y tab , selec t Diesel U nstead y Flamelet . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1698Modeling N on-P remix ed C ombustionFigur e 16.8: The E nabled D iesel U nstead y Flamelet M odel 2.If a detailed chemic al mechanism c ontaining k inetic r eactions appr opriate for compr ession ignition has not y et b een defined in y our c ase, you c an imp ort a mechanism in CHEMKIN f ormat as descr ibed in Im- porting a Volumetr ic Kinetic M echanism in CHEMKIN F ormat (p.1624 ). The mechanism c an include p ollutan t formation r eactions as w ell if y ou ar e in terested in mo deling emissions . 3.In the Boundar y tab , define the str eam c omp ositions as descr ibed in Defining the S tream C omp osi- tions (p.1702 ). 4.In the Flamelet tab , set the f ollowing flamelet par amet ers. a.Set the Numb er of G rid P oints in F lamelet . b.Set the Numb er of U nstead y Flamelets tha t ANSY S Fluen t will gener ate dur ing simula tion. c.(for multiple unst eady flamelets) S et the flamelet star t times . ANSY S Fluen t aut oma tically sets the star t time f or the first flamelet , but y ou must set the star t time f or each c onsecutiv e flamelet using the Unstead y Flamelet P aramet ers dialo g box. Open it by click ing Set F lamelet P aramet ers and en ter the star t time f or each flamelet either in seconds or in cr ank angles if the d ynamic mesh is enabled . 1699Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the S teady and U nsteady Diffusion F lamelet M odelsFigur e 16.9: The U nstead y Flamelet P aramet ers D ialo g Box ANSY S Fluen t star ts simula tion with only one flamelet , and then it aut oma tically in troduces new flamelets in to the r eacting domain a t the times y ou ha ve sp ecified . d.The default initial c ondition f or an unst eady flamelet is unbur nt. ANSY S Fluen t provides the Bur nt Initial F lamelet option tha t allo ws you t o set the initial flamelet c ondition t o a chemic al equilibr ium burnt sta te.This option is useful if y ou ar e mo deling in ternal c ombustion engines wher e residual gases may be pr esen t in the c ylinder b efore the spr ay is injec ted, which w ould b e inc orrectly mo deled b y the unbur nt sta te. Note tha t the Bur nt Initial F lamelet is only used a t case initializa tion. e.(optional) S pecify the flamelet fluid z ones . ANSY S Fluen t calcula tes diesel unst eady flamelets using the z one-a veraged pr essur e and sc alar dissipa tion a t every time st ep. By default , the a veraging is p erformed o ver all fluid z ones in the domain, but y ou c an also selec t and/or deselec t the fluid z ones using the Flamelet F luid Z ones dialo g box. Open this dialo g box by click ing Set F lamelet F luid Z ones and selec t the fluid zones t o be used f or c alcula ting a verage pr essur e and sc alar dissipa tion. If no fluid z one is se- lected, ANSY S Fluen t will c omput e domain a verage pr essur e and sc alar dissipa tion using all fluid z ones . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1700Modeling N on-P remix ed C ombustionFigur e 16.10: The F lamelet F luid Z ones D ialo g Box Note For in ternal c ombustion c ases , it is r ecommended tha t you selec t the c ylinder fluid zones and deselec t the in take and e xhaust fluid z ones . Note tha t ANSY S Fluen t calcula tes flamelets a t every time st ep of the r un. For this r eason, the option to calcula te the flamelets as a pr eprocessing st ep b efore running y our simula tion is una vailable , and Calcula te Flamelets app ears dimmed . 5.In the Table tab , set the PDF table par amet ers as descr ibed in Calcula ting the L ook-U p Tables (p.1723 ). Note tha t ANSY S Fluen t calcula tes PDF table a t every time st ep of the r un. For this r eason, the option t o calcula te the PDF table as a pr eprocessing st ep b efore running y our simula tion is una vail- able , and Calcula te PDF Table app ears dimmed . 16.3.6.1. Recommended S ettings for Int ernal C ombustion E ngines When setting up and using the D iesel U nsteady Flamelet mo del f or in ternal c ombustion engine sim- ulations , the f ollowing r ecommenda tions apply : 1.Numb er of F lamelets a.You must sp ecify a t least t wo diesel unst eady flamelets . ANSY S Fluen t will use the first flamelet t o model tr app ed bur nt gases fr om the pr evious c ycle.The sec ond flamelet will star t at the cr ank angle (CA) of fuel injec tion, specified in the Unstead y Flamelet P aramet ers dialo g box (see Figur e 16.10: The Flamelet F luid Z ones D ialog Box (p.1701 )). b.To mo del split injec tions wher e an initial fuel mass is injec ted and bur ns b efore the main fuel injec tion, three or mor e unst eady flamelets ar e requir ed. 2.Flamelet Initializa tion By default , the flamelet is initializ ed as mix ed-but-unbur nt. However, in all pr actical sc enar ios ther e is alw ays some tr app ed gas r emaining inside the c ylinder .Therefore, it is r ecommended tha t you use the Bur nt Initial F lamelet option in the Unstead y Flamelet P aramet ers dialo g box (see 1701Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the S teady and U nsteady Diffusion F lamelet M odelsFigur e 16.10: The F lamelet F luid Z ones D ialog Box (p.1701 )).When this option is selec ted, ANSY S Fluen t performs a c onstan t temp erature equilibr ium c alcula tion and sets the initial flamelet c on- dition t o a chemic al equilibr ium bur nt sta te. 3.Multi-c ycle simula tions a.To accur ately mo del multiple c ycles of in ternal c ombustion engines , the flamelets must b e reset a t the end of each c ycle.This is p erformed b y defining the Diesel U nstead y Flamelet Reset event, typic ally a t the sp ecified cr ank angle , just b efore the inlet v alve op ens. Refer to the Resetting D iesel Unsteady Flamelets (p.1702 ) for details .This appr oach is r ecommended f or mo deling the EGR tr app ed gases with the first bur nt unst eady flamelet. b.If you ar e using the Iner t (EGR) mo del in or der t o track the tr app ed iner t mix ture, you need t o define the Iner t EGR Reset event at the sp ecified cr ank angle just b efore the inlet v alve op ens. See Resetting Iner t EGR (p.1737 ) for details . 16.3.7. Resetting D iesel U nstead y Flamelets In or der t o simula te multiple c ycles in in ternal c ombustion engines , flamelets should b e reset a t the end of e very cycle. In addition, the bur ned tr app ed gases must b e mo deled , which c an b e done in one of the t wo ways.The first and r ecommended appr oach is t o use the Diesel U nstead y Flamelet Reset option. The sec ond appr oach is t o use the iner t (EGR) mo del and the Iner t EGR Reset option. You c an acc ess the Diesel U nstead y Flamelet Reset and Iner t EGR Reset options via the Dynamic Mesh E vents dialo g box.There, you need t o set the cr ank angle a t which this e vent occurs (usually shor tly b efore the inlet v alves op en) and the par ticipa ting fluid z ones (usually only the c ombustion chamb er and not the in take and e xhaust p ort zones). When the Diesel U nstead y Flamelet Reset event is e xecut ed, all flamelets ar e delet ed and a new flamelet is in troduced with a sta te set t o the pr obabilit y-weigh ted a verage c ondition of all flamelets presen t before reset. The other new flamelets ar e in troduced dur ing a new c ycle in a similar fashion to tha t descr ibed in Using the D iesel U nsteady Laminar F lamelet M odel (p.1698 ). When the iner t EGR r eset e vent is e xecut ed with the diesel unst eady flamelet mo del, the bur nt gas in the selec ted Iner t EGR R eset z ones is c onverted t o iner t, all flamelets ar e delet ed, and a new unbur nt flamelet is in troduced in to the domain. Note The Diesel U nstead y Flamelet Reset option is a vailable only when the selec ted numb er of flamelets is gr eater than one . 16.4. Defining the S tream C omp ositions In mo deling a non-pr emix ed c ombustion pr oblem, you will only sp ecify the b oundar y sp ecies (tha t is, the fuel, oxidiz er, and if nec essar y, sec ondar y str eam sp ecies). The in termedia te and pr oduc t sp ecies will b e det ermined aut oma tically. ANSY S Fluen t provides y ou with an initial list of c ommon b oundar y sp ecies (ch4 ,h2,jet-a ,n2 and o2). If your fuel and/or o xidiz er is c omp osed of diff erent sp ecies , you c an add them t o the boundar y Species list. All boundar y sp ecies must e xist in the chemic al da tabase and y ou must en ter their names in the same f ormat used in the da tabase , other wise an er ror message will b e issued . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1702Modeling N on-P remix ed C ombustionAfter defining the b oundar y sp ecies tha t will b e consider ed in the r eaction sy stem, you must define their mole or mass fr actions a t the fuel and o xidiz er inlets and a t the sec ondar y inlet , if one e xists . (If you cho ose t o define the fuel or sec ondar y str eam c omp osition empir ically, you will inst ead en ter the paramet ers descr ibed a t the end of this sec tion.) F or the e xample sho wn in Figur e 8.12: Chemic al Systems That Can B e M odeled U sing a S ingle M ixture Fraction in the Theor y Guide , for e xample , the fuel inlet consists of 60% C O4, 20% C O, 10% C O2, and 10% C3H8. Finally , the inlet str eam t emp eratures of y our r eacting sy stem ar e requir ed f or c onstr uction of the lo ok- up table and c omputa tion of the equilibr ium chemistr y mo del. For the equilibr ium chemistr y mo del, the sp ecies names ar e en tered using the Boundar y tab in the Species M odel dialo g box (Figur e 16.11: The S pecies M odel D ialog Box (B oundar y Tab) (p.1703 )). If you are gener ating a st eady or unst eady diffusion flamelet , the list of b oundar y sp ecies will b e aut oma tically filled as all the sp ecies in the CHEMKIN mechanism, and y ou will b e unable t o change these . Figur e 16.11: The S pecies M odel D ialo g Box (B oundar y Tab) The st eps f or adding new sp ecies and defining their c omp ositions ar e as f ollows: 1.(chemistr y equilibr ium chemistr y mo del only) I f your fuel, oxidiz er, or sec ondar y str eams ar e comp osed of species other than the default sp ecies list , type the chemic al formula (f or e xample ,so2 or SO2 for SO ) under Boundar y Species and click Add.The sp ecies will b e added t o the Species list. Continue in this manner un til all of the b oundar y sp ecies y ou w ant to include ar e sho wn in the Species list. To remo ve a sp ecies fr om the list , type the chemic al formula under Boundar y Species and click Remo ve.To pr int a list of all sp ecies in the ther modynamic da tabase file ( thermo.db ) in the c onsole windo w, click List A vailable S pecies . 2.(non-equilibr ium chemistr y mo dels) Optionally , selec t the b oundar y sp ecies as descr ibed in Overview of the P roblem S etup P rocedur e (p.1688 ). 3.Under Specify S pecies In , specify whether y ou w ant to en ter the Mass F raction or Mole F raction .Mass Fraction is the default. 1703Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Defining the S tream C omp ositions4.For each r elevant species in the Species list, specify its mass or mole fr action f or each str eam ( Fuel,Oxid, or Second as appr opriate) b y en tering v alues in the table . Note tha t if y ou change fr om Mass F raction to Mole F raction (or vic e versa), all v alues will b e aut oma tically c onverted if the y sum t o 0 or 1, so b e sur e that you ar e en tering either all mass fr actions or all mole fr actions as appr opriate. If the v alues do not sum to 0 or 1, an er ror will b e issued . 5.Under Temp erature, specify the f ollowing inputs: Fuel is the t emp erature of the fuel inlet in y our mo del. In adiaba tic simula tions , this input (t ogether with the o xidiz er inlet t emp erature) det ermines the inlet str eam t emp eratures tha t will b e used b y ANSY S Fluen t. In non-adiaba tic sy stems , this input should ma tch the inlet ther mal b oundar y condition tha t you will use in ANSY S Fluen t (although y ou will en ter this b oundar y condition again in the ANSY S Fluen t session). If your ANSY S Fluen t mo del will use liquid fuel or c oal c ombustion, define the inlet fuel t em- perature as the t emp erature at which v aporization/de volatiliza tion b egins (tha t is, the Vaporization Temp erature specified f or the discr ete-phase ma terial—see Setting M aterial P roperties f or the D iscrete Phase (p.2008 )). For such non-adiaba tic sy stems , the inlet t emp erature will b e used only t o adjust the look-up table gr id (f or e xample , the discr ete en thalp y values f or which the lo ok-up table is c omput ed). Note tha t if y ou ha ve mor e than one fuel inlet , and these inlets ar e not a t the same t emp erature, you must define y our sy stem as non-adiaba tic. In this c ase, you should en ter the fuel inlet t emp erature as the v alue a t the dominan t fuel inlet. Oxid is the t emp erature of the o xidiz er inlet in y our mo del. The issues r aised in the discussion of the input of the fuel inlet t emp erature (dir ectly ab ove) p ertain t o this input as w ell. Second is the t emp erature of the sec ondar y str eam inlet in y our mo del. (This it em will app ear only when y ou have defined a sec ondar y inlet.) The issues r aised in the discussion of the input of the fuel inlet t emp er- ature (dir ectly ab ove) p ertain t o this input as w ell. For additional inf ormation, see the f ollowing sec tions: 16.4.1. Setting B oundar y Stream S pecies 16.4.2. Modifying the D atabase 16.4.3. Comp osition Inputs f or Empir ically-D efined F uel S treams 16.4.4. Modeling Liquid F uel C ombustion U sing the N on-P remix ed M odel 16.4.5. Modeling C oal C ombustion U sing the N on-P remix ed M odel 16.4.1. Setting B oundar y Stream S pecies In combustion, a lar ge numb er of in termedia te and pr oduc t sp ecies ma y be pr oduced fr om a small numb er of initial b oundar y sp ecies . In ANSY S Fluen t you must sp ecify only the sp ecies c omp osition of your b oundar y sp ecies in the fuel, oxidiz er, and (if appr opriate) sec ondar y str eams . ANSY S Fluen t will calcula te all in termedia te and pr oduc t sp ecies aut oma tically.The f ollowing suggestions ma y be helpful in the definition of the sy stem chemistr y: •For coal c ombustion, char in the c oal should b e represen ted b y C(s). Imp ortant Care should b e tak en t o distinguish a tomic c arbon, C, from solid c arbon, C(s). Atomic carbon should b e selec ted only if y ou ar e using the empir ically-defined input metho d. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1704Modeling N on-P remix ed C ombustion•If your fuel c omp osition is k nown empir ically (f or e xample , C0.9 H3 O0.2), use the option f or an empir ically- defined str eam (see b elow). •If you w ant to include the sulfur tha t ma y be pr esen t in a h ydrocarbon fuel, not e tha t this ma y hinder the convergenc e of the equilibr ium solv er, esp ecially if the c oncentration of sulfur is small. It is ther efore re- commended tha t you include sulfur in the c alcula tion only if it is pr esen t in c onsider able quan tities . 16.4.1.1. Including C ondensed Sp ecies In addition t o gaseous sp ecies , liquid and solid sp ecies c an b e included in the chemistr y calcula tions . They are of ten indic ated b y an “l” or an “s” in par entheses af ter the sp ecies name . If you add a c on- densed sp ecies t o the equilibr ium chemic al sy stem, its densit y will b e retrieved fr om ANSY S Fluen t’s chemic al pr operty da tabase file propdb.scm if y ou ar e using the ther modynamic da tabase file thermo.db tha t is also supplied with ANSY S Fluen t. If you ar e using a cust om ther modynamic database file and w ant to include a c ondensed sp ecies in the equilibr ium sy stem tha t do es not e xist in propdb.scm , a densit y of 1000 k g/m3 will b e assumed .The c ondensed sp ecies densit y can b e changed in the Create/Edit M aterials D ialog Box (p.3386 ) after the PDF table has b een c alcula ted. If you mo dify the c ondensed sp ecies densit y in this manner , you will then need t o recalcula te the PDF table . 16.4.2. Modifying the D atabase If you w ant to include a new sp ecies in y our r eacting sy stem tha t is not a vailable in the chemic al database , you c an add it t o the da tabase file ,thermo.db .The f ormat for thermo.db is detailed in [59] (p.4008 ). If you cho ose t o mo dify the standar d da tabase file , you should cr eate copies of the or iginal file. 16.4.3. Comp osition Inputs f or E mpir ically-D efined F uel S treams As men tioned in Defining the P roblem Type (p.1688 ), you c an define the c omp osition of a fuel str eam (tha t is, the standar d fuel or a sec ondar y fuel) empir ically. For an empir ically-defined str eam, you will need t o en ter the a tomic mass or mole fr actions in addition t o the inputs f or lo wer calor ic (hea ting) value of the fuel and the mean sp ecific hea t of the fuel tha t were descr ibed pr eviously . The hea t of f ormation of an empir ically defined str eam is c alcula ted fr om the hea ting v alue and the atomic c omp osition. The fuel inlet t emp erature and fuel sp ecific hea t are used t o calcula te the sensible enthalp y.The molecular w eigh t is used f or the c omputa tion of the unbur nt str eam densit y. Note tha t the unbur nt densit y is only r equir ed if the str eam en ters via an inlet b oundar y, or if y ou ar e using the partially-pr emix ed mo del. When an empir ically-defined fuel or sec ondar y str eam is sp ecified in the Chemistr y tab (equilibr ium chemistr y mo del only) of the Species M odel dialo g box, you must sp ecify the a tom fr actions of C, H, O, N, and S in tha t str eam inst ead of the sp ecies mass or mole fr actions .To avoid c onfusion, the sp ecies fraction inputs f or an empir ically-defined str eam will b e gr ayed out in the table within the Boundar y tab, leaving only the fields f or a tom fr actions (tha t is,c,h,o,n, and s). 16.4.4. Modeling Liquid F uel C ombustion U sing the N on-P remix ed M odel Liquid fuel c ombustion c an b e mo deled with the discr ete phase and non-pr emix ed mo dels . In ANSY S Fluen t, the fuel v apor, which is pr oduced b y evaporation of the liquid fuel, is defined as the fuel str eam. 1705Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Defining the S tream C omp ositions(See Defining the S tream C omp ositions (p.1702 ).) The liquid fuel tha t evaporates within the domain app ears as a sour ce of the mean fuel mix ture fraction. Within ANSY S Fluen t, you define the liquid fuel discr ete-phase mo del in the usual w ay.The gas phase (oxidiz er) flo w inlet is mo deled using an inlet mix ture fraction of z ero and the fuel dr oplets ar e in tro- duced as discr ete phase injec tions (see Setting Initial C onditions f or the D iscrete Phase (p.1943 )).The property inputs f or the liquid fuel dr oplets ar e unalt ered b y the non-pr emix ed mo del (see Setting Material P roperties f or the D iscrete Phase (p.2008 )). Note tha t when y ou ar e request ed t o input the gas phase sp ecies destina tion f or the e vaporating liquid , you should sp ecify the sp ecies tha t mak e up the evaporating str eam. If the fuel str eam w as defined as a mix ture of c omp onen ts, you should selec t the lar gest of these comp onen ts as the “evaporating sp ecies ”. ANSY S Fluen t will ensur e tha t the mass e vaporated fr om the liquid dr oplet en ters the gas phase as a sour ce of the fuel mix ture tha t you defined .The e vaporating species y ou selec t her e is used only t o comput e the diffusion c ontrolled dr iving f orce in the e vaporation rate. 16.4.5. Modeling C oal C ombustion U sing the N on-P remix ed M odel If your mo del in volves c oal c ombustion, the fuel and sec ondar y str eam c omp ositions c an b e input in one of se veral w ays.You c an use a single mix ture fraction (fuel str eam) t o represen t the c oal, defining the fuel c omp osition as a mix ture of v olatiles and char (solid c arbon). Alternatively, you c an use t wo mixture fractions (fuel and sec ondar y str eams), defining the v olatiles and char separ ately. In t wo-mix ture- fraction mo dels f or c oal c ombustion, the fuel str eam r epresen ts the char and the sec ondar y str eam represen ts volatiles .This sec tion descr ibes the mo deling options and sp ecial input pr ocedur es for c oal combustion mo dels using the non-pr emix ed appr oach. There ar e thr ee options f or c oal c ombustion: •When c oal is the only fuel in the sy stem, you c an mo del the c oal using t wo mix ture fractions , wher e the primar y str eam r epresen ts the char and the sec ondar y str eam r epresen ts the v olatiles . Gener ally, the char stream c omp osition is defined as 100% C(s). The v olatile str eam c omp osition is defined b y selec ting appr o- priate sp ecies and setting their mole or mass fr actions . Alternatively, you c an use the empir ical metho d (input of a tom fr actions) f or defining these c omp ositions . Imp ortant Using t wo mix ture fractions t o mo del c oal c ombustion is mor e accur ate than using one mixture fraction as the v olatile and char str eams ar e mo deled separ ately. However, the two-mix ture-fraction mo del incurs signific ant additional c omputa tional e xpense sinc e the multi-dimensional PDF in tegrations ar e performed a t run time . •When c oal is the only fuel in the sy stem, you c an cho ose t o mo del the c oal using a single mix ture fraction (the fuel str eam). When this appr oach is adopt ed, the fuel c omp osition y ou define includes b oth v olatile species and char . Char is t ypic ally r epresen ted b y including C(s) in the sp ecies list. You c an define the fuel Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1706Modeling N on-P remix ed C ombustionstream c omp osition b y selec ting appr opriate sp ecies and setting their mole fr actions , or b y using the em- pirical metho d (input of a tom fr actions). Definition of the c omp osition is descr ibed in detail b elow. Imp ortant Using a single mix ture fraction f or c oal c ombustion is less accur ate than using t wo mix ture fractions . However, convergenc e in ANSY S Fluen t should b e substan tially fast er than the two-mix ture-fraction mo del. •When c oal is used with another (gaseous or liquid) fuel of diff erent comp osition, you must mo del the c oal with one mix ture fraction and use a sec ond mix ture fraction t o represen t the sec ond (gaseous or liquid) fuel. The str eam asso ciated with the c oal c omp osition is defined as detailed b elow for single-mix ture- fraction mo dels . 16.4.5.1. Defining the C oal C omp osition: Single-M ixture-Fraction Mo dels When c oal is mo deled using a single mix ture fraction (the fuel str eam), the fuel str eam c omp osition can b e input using the c onventional appr oach or the empir ical fuel appr oach. •Conventional appr oach: To use the c onventional appr oach, you will need t o define the mix ture of sp ecies in the c oal and their mole or mass fr actions in the fuel str eam. Use the Boundar y tab in the Species M odel dialo g box to input the list of sp ecies (f or e xample , C3H8, CH4, CO, CO2, C(s)) tha t appr oxima te the c oal comp osition, and their mole or mass fr actions . Note tha t C(s) is used t o represen t the char c ontent of the c oal. For e xample , consider a c oal tha t has a molar c omp osition of 40% v olatiles and 60% char on a dr y ash fr ee (DAF) basis . Assuming the v olatiles c an b e represen ted b y an equimolar mix ture of C3H8 and C O, the fuel str eam c omp os- ition defined in the Boundar y tab w ould b e C3H8=0.2, CO = 0.2, and C(s)=0.60. Note tha t the c oal comp osition should alw ays be defined on an ash-fr ee basis , even if ash will b e consider ed in the ANSY S Fluen t calcula tion. To define ash pr operties, go t o the Create/Edit M aterials dialo g box and selec t combusting- par ticle as the Material Type. The f ollowing table illustr ates the c onversion fr om a t ypic al mass-based pr oxima te analy sis t o the species fr action inputs r equir ed b y ANSY S Fluen t. Note tha t the c onversion r equir es tha t you mak e an assumption r egar ding the sp ecies r epresen ting the v olatiles . Here, the v olatiles ar e assumed t o exist as an equimolar mix of pr opane and c arbon mono xide . Mole F raction (DAF)Moles (DAF)Mass F raction (DAF)Weigh t % Proxima te Analy sis 30 Volatiles 0.07134 0.004625 0.2035 –C3H8 0.07134 0.004625 0.1295 – CO 0.85732 0.05558 0.667 60 Fixed C arbon (C(s)) - - - 10 Ash 1.0 0.06483 (Total) 1707Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Defining the S tream C omp ositionsMoistur e in the c oal c an b e consider ed b y adding it in the fuel c omp osition as liquid w ater, H2O(l). The moistur e can also b e defined as w ater v apor, H2O, provided tha t the c orresponding la tent hea t is included in the discr ete phase ma terial inputs in ANSY S Fluen t. If the liquid w ater is used as a boundar y sp ecies , it should b e remo ved fr om the list of e xcluded sp ecies (see Forcing the Ex clusion and Inclusion of E quilibr ium S pecies (p.1714 )). Imp ortant Note tha t if w ater is included in the c oal, the w ater release is not mo deled as e vaporation, which is t ypic ally the c ase in the w et combustion mo del, descr ibed in Particle Types (p.1947 ). •Empir ical fuel appr oach: To use the empir ical appr oach, enable the Empir ical F uel S tream option in the Chemistr y tab . This metho d is ideal if y ou ha ve an elemen tal analy sis of the c oal. In the Chemistr y tab , enter the lo wer hea ting v alue and mean sp ecific hea t of the c oal. ANSY S Fluen t will use these inputs t o det ermine the mole fr actions of the chemic al sp ecies y ou ha ve in- cluded in the sy stem. Then, in the Boundar y tab , define the a tom fr actions of C, H, N, S, and O in the fuel str eam. Note tha t for b oth of these c omp osition input metho ds, you should tak e care to distinguish a tomic carbon, C, from solid c arbon, C(s). Atomic c arbon should only b e selec ted if y ou ar e using the empir- ical fuel input metho d. See Additional C oal M odeling Inputs in ANSY S Fluen t (p.1710 ) for details ab out fur ther inputs f or modeling c oal c ombustion. 16.4.5.2. Defining the C oal C omp osition: Two-M ixture-Fraction Mo dels You c an mo del c oal using the t wo mix ture fractions mo del, wher e the pr imar y str eam r epresen ts the char and the sec ondar y str eam r epresen ts the v olatiles . As in single-mix ture-fraction c ases , the fuel str eam and sec ondar y str eam c omp ositions in a t wo- mixture-fraction c ase c an b e en tered using either the c onventional appr oach or the empir ical fuel appr oach. •Conventional appr oach: To use the c onventional appr oach, you will need t o define the mix ture of sp ecies in the c oal and their mole or mass fr actions in the fuel and sec ondar y str eams . Use the Boundar y tab of Species M odel dialo g box to define the mole or mass fr actions of v olatile species in the sec ondar y str eam (f or e xample , C3H8, CH4, CO, CO2, C(s)). Next, define the mole or mass fr actions of sp ecies used t o represen t the char . Gener ally, you will sp ecify 100% C(s) f or the fuel str eam. •Empir ical fuel appr oach: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1708Modeling N on-P remix ed C ombustionTo use the empir ical fuel appr oach, enable the Empir ical S econdar y Stream option in the Chemistr y tab f or the v olatile (sec ondar y) str eam. This metho d is ideal if y ou ha ve an elemen tal analy sis of the c oal. In the Chemistr y tab , input the lo wer hea ting v alue and mean sp ecific hea t of the c oal v olatiles . Then, in the Boundar y tab , define the mole or mass fr actions of sp ecies used t o represen t the char . Gener ally, you will sp ecify 100% C(s) f or the fuel str eam. Finally , define the a tom fr actions of C, H, N, S, and O in the v olatiles . ANSY S Fluen t will use these inputs t o det ermine the mole fr actions of the chemic al sp ecies y ou ha ve included in the sy stem. For e xample , consider c oal with the f ollowing DAF (dr y ash fr ee) da ta and elemen tal analy sis: Wt % (DAF) Wt % (dr y) Proxima te Analy sis 30.4 28 Volatiles 69.6 64 Char (C(s)) - 8 Ash Wt % (DAF) Wt % (DAF) Elemen t 89.3 89.3 C 5.0 5.0 H 3.4 3.4 O 2.3 1.5 N - 0.8 S (Note tha t in the final c olumn, for mo deling simplicit y, the sulfur c ontent of the c oal has b een combined in to the nitr ogen mass fr action.) You c an c ombine the pr oxima te and ultima te analy sis da ta to yield the f ollowing elemen tal c om- position of the v olatile str eam: Mole F raction Moles Mass F raction Mass Elemen t 0.24 5.4 0.65 (89.3 - 69.6) C 0.70 16 0.16 5.0 H 0.03 0.7 0.11 3.4 O 0.03 0.6 0.08 2.3 N 22.7 30.4 Total This adjust ed c omp osition is used t o define the sec ondar y str eam (v olatile) c omp osition. The lo wer hea ting v alue of the v olatiles c an b e comput ed fr om the k nown hea ting v alue of the coal and the char (DAF): You c an c omput e the hea ting v alue of the v olatiles as (16.2) 1709Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Defining the S tream C omp ositionsor (16.3) Note tha t for b oth of these c omp osition input metho ds, you should tak e care to distinguish a tomic carbon, C, from solid c arbon, C(s). Atomic c arbon should only b e selec ted if y ou ar e using the empir- ical fuel input metho d. 16.4.5.3. Additional C oal Mo deling Inputs in ANSY S Fluent Within ANSY S Fluen t, the DPM c oal c ombustion simula tion is defined as usual when the non-pr emix ed combustion mo del is selec ted.The air (o xidiz er) inlets ar e defined as ha ving a mix ture fraction v alue of zero. No gas phase fuel inlets will b e included and the sole sour ce of fuel will c ome fr om the c oal devolatiliza tion and char bur nout. The c oal par ticles ar e defined as injec tions using the Set Injec tion Properties dialo g box in the usual w ay, and ph ysical pr operties f or the c oal ma terial ar e sp ecified as descr ibed in Setting M aterial P roperties f or the D iscrete Phase (p.2008 ). Rememb er the f ollowing issues when y ou ar e defining injec tions and discr ete-phase ma terial pr operties f or c oal ma terials: •In the Set Injec tion P roperties dialo g box, you will sp ecify f or the Oxidizing S pecies one of the c omp on- ents of the o xidiz er str eam. This sp ecies c oncentration field will b e used t o calcula te the diffusion-c ontrolled driving f orce in the char bur nout la w (if applic able), and is O2 by default. The sp ecific ation of the char and v olatile str eams diff ers dep ending on the t ype of mo del y ou ar e defining: –If coal is mo deled using a single mix ture fraction, the gas phase sp ecies r epresen ting the v olatiles and the char c ombustion ar e represen ted b y the mix ture fraction used b y the non-pr emix ed c ombustion model. –If coal is mo deled using t wo mix ture fractions , rather than sp ecifying a destina tion sp ecies f or the volatiles and char , you will inst ead sp ecify the Devolatilizing S tream (as sec ondar y) and the Char Stream (as pr imar y). –If coal is mo deled using one mix ture fraction, and another fuel is mo deled using a sec ond mix ture fraction, you should sp ecify the str eam r epresen ting the c oal as b oth the Devolatilizing S tream and the Char S tream . •In the Create/Edit M aterials dialo g box,Vaporization Temp erature should b e set equal t o the fuel inlet temp erature.This t emp erature controls the onset of the de volatiliza tion pr ocess.The fuel inlet t emp erature that you define in the Boundar y tab of the Species M odel dialo g box should b e set t o the t emp erature at which y ou w ant to initia te de volatiliza tion. This w ay, the lo ok-up tables will include the appr opriate temp erature range f or y our pr ocess. •In the Create/Edit M aterials dialo g box,Volatile C omp onen t Fraction and Combustible F raction should be set t o values tha t are consist ent with the c oal c omp osition used t o define the fuel (and sec ondar y) stream c omp osition. •Also in the Create/Edit M aterials dialo g box, you will b e pr ompt ed f or the Bur nout S toichiometr ic R atio and f or the Latent Heat.The Bur nout S toichiometr ic R atio is used in the c alcula tion of the diffusion controlled bur nout r ate but has no other impac t on the sy stem chemistr y when the non-pr emix ed c om- bustion mo del is used .The Bur nout S toichiometr ic R atio is the mass of o xidan t requir ed p er mass of char .The default v alue of 2.67 assumes tha t C(s) is o xidiz ed b y O2 to yield C O2.The Latent Heat input determines the hea t requir ed t o gener ate the v apor phase v olatiles defined in the non-pr emix ed sy stem chemistr y.You c an usually set this v alue t o zero when the non-pr emix ed mo del is used , sinc e your Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1710Modeling N on-P remix ed C ombustiondefinition of v olatile sp ecies will ha ve been based on the o verall hea ting v alue of the c oal. However, if the c oal c omp osition includes the w ater content, the la tent hea t should b e set as f ollows: –Set the la tent hea t to zero if the w ater content of the c oal has b een defined as H2O(L) . In this c ase, the system chemistr y will include the la tent hea t requir ed t o vaporize the liquid w ater. –Set the la tent hea t to the v alue f or w ater (2.25 106 J/kg), adjust ed b y the mass loading of w ater in the v olatiles , if the w ater content of the c oal has b een defined using w ater vapor,H2O . In this c ase, the water content you defined will b e evolved along with the other sp ecies in the c oal but the sy stem chemistr y do es not include the la tent hea t eff ect. •The Densit y you define f or the c oal in the Create/Edit M aterials dialo g box should b e the appar ent densit y, including ash c ontent. •You will not b e ask ed t o define the Heat of Reac tion f or Bur nout for the char c ombustion. 16.4.5.4. Postpr ocessing N on-P remix ed Mo dels of C oal C ombustion ANSY S Fluen t reports the r ate of v olatile r elease fr om the c oal using the DPM E vaporation/D evolat- iliza tion postpr ocessing v ariable .The r ate of char bur nout is r eported in the DPM Bur nout variable . 16.4.5.5. The C oal C alculat or The Coal C alcula tor dialo g box aut oma tes the c alcula tions descr ibed ab ove for setting up a c oal case fr om the pr oxima te and ultima te analy ses. 1711Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Defining the S tream C omp ositionsFigur e 16.12: The C oal C alcula tor D ialo g Box The inputs t o the Coal C alcula tor dialo g box are: 1.Coal Proxima te Analy sis, which is the mass fr action of Volatile, Fixed C arb on, Ash and Moistur e in the c oal. 2.Coal Ultima te Analy sis, which is the mass fr action of a tomic C, H, O, N and optionally S, in the D ry-Ash- Free (DAF) c oal. 3.The option t o use a Secondar y Stream . If enabled , the t wo mix ture fraction mo del will b e set with the primar y str eam r epresen ting char as , and an empir ical sec ondar y str eam r epresen ting the v olatiles . 4.The Coal P article M aterial N ame . A DPM C ombusting P article M aterial will b e created with this name . The default name is coal-par ticle . 5.The Coal A s-Rec eived HCV (Higher C alor ific Value). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1712Modeling N on-P remix ed C ombustion6.The High Temp erature Volatile Yield . Proxima te analy ses ar e gener ally done with slo wer hea ting r ates and lo wer temp eratures than w ould o ccur in a r eal flame .Therefore, enhanc ed de volatization a t higher temp eratures c an c ause the v olatile yield t o exceed the pr oxima te analy sis fr action. To mo del this , the actual v olatile fr action used is c alcula ted as tha t specified in the Proxima te Analy sis input multiplied by the High Temp erature Volatile Yield .The ac tual Fixed C arb on fraction is then c alcula ted as one minus the sum of the ac tual Volatile,Ash, and Moistur e fractions . 7.Fraction of N in C har (DAF) .This input is used in c alcula ting the split of a tomic nitr ogen f or the F uel NOx mo del. When the OK butt on is click ed, ANSY S Fluen t mak es the f ollowing changes: a.The empir ical fuel a tomic c omp ositions in the Boundar y tab ar e set , and the Non-A diaba tic mo del is enabled as r equir ed f or DPM. The Empir ical Fuel L ower C alor ific Value is c alcula ted as f ollows. First the DAF L CV of the c oal is c omput ed as , (16.4) wher e and are the pr oxima te moistur e and ash fr actions , is the ultima te fraction, and are the molecular w eigh t of w ater and a tomic h ydrogen, respectively, and is the la tent hea t of w ater. If you ar e using the Secondar y Stream option, is c alcula ted fr om using , (16.5) wher e and are the pr oxima te fix ed c arbon and v olatile fr actions , respect- ively. b.A combusting par ticle ma terial is cr eated with Volatile C omp onen t Fraction and Combustible Fraction calcula ted fr om the ultima te and pr oxima te analy ses.The D iscrete Phase M odel (DPM) is enabled . c.For the F uel NO x mo del, the char N c onversion is set t o NO, and the F uel NO x Volatile and Char mass fr actions ar e set acc ording t o the ultima te and pr oxima te comp ositions . Note tha t even though some of the F uel NO x par amet ers ar e changed , the F uel NO x mo del itself is not enabled . After the Coal C alcula tor has set up the r elevant mo dels , you must build the PDF Table b y click ing Calcula te PDF Table in the Table tab .You will also need t o cr eate injec tions if y ou ha ve not done this y et. After converging y our c oal c ombustion c ase, you ma y want to enable the NO x mo del f or postpr ocessing nitr ogen-o xide p ollutan ts. 16.5. Setting U p Control P aramet ers For inf ormation ab out setting up c ontrol par amet ers, see the f ollowing sec tions: 16.5.1. Forcing the Ex clusion and Inclusion of E quilibr ium S pecies 16.5.2. Defining the F lamelet C ontrols 16.5.3. Zeroing S pecies in the Initial U nsteady Flamelet 1713Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p Control Paramet ers16.5.1. Forcing the E xclusion and Inclusion of E quilibr ium S pecies Because ANSY S Fluen t calcula tes all in termedia te and pr oduc t sp ecies aut oma tically dur ing the equi- librium c alcula tion, certain sp ecies will b e included tha t are gener ally not in chemic al equilibr ium. Principal among these ar e the NO x sp ecies . Specific ally, the NO x reaction r ates ar e slo w and should not b e treated using an equilibr ium assumption. Inst ead, the NO x concentration is pr edic ted most accur ately using the ANSY S Fluen t NO x postpr ocessor , wher e finit e-rate kinetics ar e included (see NOx Formation (p.1823 )).The NO x sp ecies c an b e saf ely e xcluded fr om the equilibr ium c alcula tion sinc e they are pr esen t at low concentrations and ha ve little impac t on the densit y, temp erature, and other species . To force the e xclusion of a sp ecies fr om the equilibr ium c alcula tion, click the Control tab in the Species Model dialo g box (Figur e 16.13: The S pecies M odel D ialog Box (C ontrol Tab) (p.1714 )). Figur e 16.13: The S pecies M odel D ialo g Box (C ontrol Tab) Under Species E xcluded F rom E quilibr ium , enter the chemic al formula f or the desir ed sp ecies in the Add/Remo ve Species field . Next, click Add to add the sp ecies t o the Species list or Remo ve to remo ve an e xisting sp ecies fr om the Species list. If ther e ar e sp ecies tha t you w ant to include in y our PDF table tha t would b e ignor ed b y ANSY S Flu- ent due t o their lo w concentration (f or e xample , CH, CH2, CH3 for the NOx calcula tion), you c an f orce ANSY S Fluen t to include them using the t ext interface: define → models → species → non-premixed-combustion When the c onsole windo w pr ompts y ou with Force Equilibrium Species to Include... , specify the appr opriate sp ecies b y en tering the chemic al formula(s) in double quot es (f or e xample , "ch" ,"ch2" ). Note tha t you will ha ve to first set up the inputs f or the fuel and o xidiz er b efore you ar e giv en the option t o include the sp ecies . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1714Modeling N on-P remix ed C ombustion16.5.2. Defining the F lamelet C ontrols When the st eady diffusion flamelet mo del is selec ted, and y ou ha ve created or imp orted a flamelet , you c an adjust the c ontrols f or the flamelet solution in the Control tab of the Species M odel dialo g box (Figur e 16.14: The S pecies M odel D ialog Box (C ontrol Tab) f or the S teady Diffusion F lamelet M od- el (p.1715 )). Figur e 16.14: The S pecies M odel D ialo g Box (C ontrol Tab) f or the S tead y D iffusion F lamelet Model The Initial F our ier N umb er sets the first time st ep f or the solution of the flamelet equa tions ( Equa- tion 8.47 and Equa tion 8.48 in the Theor y Guide ).This first time st ep is c alcula ted as the e xplicit stabilit y- limit ed diffusion time st ep multiplied b y this v alue . If the solution div erges b efore the first time st ep is complet e, the v alue should b e lowered. The Four ier N umb er M ultiplier incr eases the time st ep a t subsequen t times . Every time st ep af ter the first is multiplied b y this v alue . If the solution div erges af ter the first time st ep, this v alue should be reduc ed. During the numer ical in tegration of the flamelet equa tions , the lo cal er ror is c ontrolled t o be less than (16.6) wher e represen ts the sp ecies mass fr actions and t emp erature at point in the 1D flamelet. is the v alue of the Rela tive Error Toler anc e and is the v alue of the Absolut e Error Toler anc e, both of which y ou c an sp ecify . 1715Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p Control Paramet ersBecause st eady flamelets ar e obtained b y time-st epping , the y are consider ed c onverged only when the maximum absolut e change in sp ecies fr action or t emp erature at an y discr ete mix ture-fraction p oint is less than the sp ecified Flamelet C onvergenc e Toler anc e. Between time st eps, the flamelet sp ecies fractions and t emp erature will sometimes oscilla te, which c auses absolut e changes tha t are alw ays greater than the flamelet c onvergenc e toler ance. In such c ases , ANSY S Fluen t will st op the flamelet calcula tion af ter the t otal elapsed time has e xceeded the Maximum In tegration Time . 16.5.3. Zeroing S pecies in the Initial U nstead y Flamelet When mo deling gas-phase c ombustion using the E uler ian unst eady laminar flamelet mo del, the flamelet fields ar e initializ ed t o a bur ning , steady-flamelet solution in or der t o mo del ignition. However, assuming st eady-flamelet pr ofiles f or slo w-forming sp ecies is inaccur ate. A b etter appr oxima tion is t o iden tify the slo w sp ecies and t o set them t o zero, which is done in the Control tab . By default , ANSY S Fluen t selec ts some NOx species (NO , NO2, N2O, N, NH, NH2, NH3, NNH, HCN, HNO , CN, H2CN, HCNN, HCNO , HOCN, HNC O, HCO), as w ell as liquid w ater H2 and solid c arbon C t o be zeroed. See Figur e 16.15: Metho d to Zero Out the S low C hemistr y Species (p.1716 ). Figur e 16.15: Metho d to Zero Out the S low C hemistr y Species 16.6. Calcula ting the F lamelets For inf ormation ab out c alcula ting flamelets , see the f ollowing sec tions: 16.6.1. Steady Diffusion F lamelet 16.6.2. Unsteady Diffusion F lamelet 16.6.3. Saving the F lamelet D ata 16.6.4. Postpr ocessing the F lamelet D ata 16.6.1. Stead y Diffusion F lamelet In the Flamelet tab of the Species M odel dialo g box (Figur e 16.16: The S pecies M odel D ialog Box (Flamelet Tab) (p.1717 )), you will en ter v alues f or par amet ers of the flamelet(s). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1716Modeling N on-P remix ed C ombustionFigur e 16.16: The S pecies M odel D ialo g Box (F lamelet Tab) The Flamelet P aramet ers are as f ollows: Numb er of G rid P oints in F lamelet specifies the numb er of mix ture fraction gr id p oints distr ibut ed b etween the o xidiz er ( ) and the fuel ( ). Incr eased r esolution will pr ovide gr eater accur acy, but sinc e the flamelet sp ecies and t emp erature are solv ed c oupled and implicit in spac e, the solution time and memor y requir emen ts incr ease gr eatly with the numb er of grid p oints. Maximum N umb er of F lamelets specifies the maximum numb er of flamelet pr ofiles t o be calcula ted. If the flamelet e xtinguishes b efore this numb er is r eached , flamelet gener ation is halt ed and the ac tual numb er of flamelets in the flamelet library will b e less than this v alue . Initial Sc alar D issipa tion is the sc alar dissipa tion of the first flamelet in the libr ary.This c orresponds t o in Equa tion 8.53 in the Theor y Guide . Scalar D issipa tion M ultiplier specifies the r atio of the sc alar dissipa tion st ep in which succ essiv e flamelets ar e gener ated when the scalar dissipa tion is less than 1 s-1.This c orresponds t o for < 1 in Equa tion 8.53 in the Theor y Guide . 1717Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Calcula ting the F lameletsScalar D issipa tion S tep specifies the in terval between sc alar dissipa tion v alues (in s-1) for which multiple flamelets will b e calcula ted. This c orresponds t o for ≥ 1 in Equa tion 8.53 in the Theor y Guide . Note Scalar D issipa tion M ultiplier and Scalar D issipa tion S tep are used t o sp ecify the in- terval of sc alar dissipa tion f or < 1 and ≥ 1, respectively. For e xample , for initial sc alar dissipa tion of 1e-3 s-1 with a Scalar D issipa tion M ultiplier of 10, and a Scalar D issipa- tion S tep of 5, the flamelets will b e gener ated with sc alar dissipa tions of 1e-3, 1e-2, 0.1, 1.0, 6, 11, 16, and so on. User D efined F lamelet P aramet ers enables y ou t o ho ok a user-defined func tion f or sc alar dissipa tion and mean mix ture fraction (or pr ogress variable) gr id discr etiza tion Automa ted G rid Refinemen t emplo ys an adaptiv e algor ithm, which inser ts gr id p oints so tha t the change of v alues , as w ell as the change of slop es, between succ essiv e gr id p oints is less than user-sp ecified t oler ances. For inf ormation about this option, refer to Steady Diffusion F lamelet A utoma ted G rid R efinemen t in the Theor y Guide . Onc e this option is enabled , you c an sp ecify the f ollowing par amet ers: Initial N umb er of G rid P oints in F lamelet calcula tes a st eady solution on a c oarse gr id, with a default of . See Equa tion 8.54 in the Theor y Guide . Maximum N umb er of G rid P oints in F lamelet has a default of . Maximum C hange in Value R atio has a default of and is in Equa tion 8.28 in the Theor y Guide . Maximum C hange in S lope Ratio has a default of and is in Equa tion 8.29 in the Theor y Guide . Click Calcula te Flamelets to begin the diffusion flamelet c alcula tion. Sample output f or a flamelet calcula tion is sho wn b elow. Generating flamelet 1 at scalar dissipation 0.01 /s Time (s) Temp (K) Residual 1.679e-05 2233.7 3.779e+00 5.038e-05 2233.0 7.734e-02 1.175e-04 2231.5 1.648e-01 2.519e-04 2228.6 3.652e-01 5.206e-04 2223.6 8.295e-01 1.058e-03 2215.7 2.100e+00 2.133e-03 2205.5 3.540e+00 4.282e-03 2197.0 4.607e+00 8.581e-03 2193.6 6.639e+00 1.718e-02 2193.1 4.905e+00 3.437e-02 2193.4 5.792e+00 6.877e-02 2194.3 4.659e+00 1.375e-01 2195.3 3.922e+00 2.751e-01 2192.2 3.181e+00 5.502e-01 2188.6 2.549e+00 1.100e+00 2184.8 1.639e+00 2.201e+00 2182.9 4.604e+00 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1718Modeling N on-P remix ed C ombustion4.402e+00 2186.8 1.307e+00 8.804e+00 2189.6 4.420e-01 1.761e+01 2190.0 8.581e-02 3.522e+01 2190.0 1.199e-02 7.043e+01 2190.0 1.735e-03 1.409e+02 2190.0 4.217e-04 2.817e+02 190.0 6.892e-05 5.635e+02 2190.0 6.777e-06 Flamelet successfully generated 16.6.2. Unstead y Diffusion F lamelet In the Flamelet tab of the Species M odel dialo g box (Figur e 16.17: The F lamelet Tab f or the U nsteady Diffusion F lamelet M odel (p.1719 )), you will en ter v alues f or par amet ers of the flamelet. Figur e 16.17: The F lamelet Tab f or the U nstead y D iffusion F lamelet M odel The Unstead y Flamelet P aramet ers are as f ollows: Numb er of G rid P oints in F lamelet specifies the numb er of mix ture fraction gr id p oints distr ibut ed b etween the o xidiz er ( ) and the fuel ( ). Incr eased r esolution will pr ovide gr eater accur acy, but sinc e the flamelet sp ecies and t emp erature are solv ed c oupled and implicit in spac e, the solution time and memor y requir emen ts incr ease with the numb er of grid p oints. Mixture Fraction L ower Limit f or Initial P robabilit y is the mix ture fraction ab ove which the mar ker pr obabilit y will b e initializ ed t o 1, and b elow which the mar ker pr obabilit y will b e initializ ed t o 0. In gener al, it should b e set gr eater than the st oichiometr ic mixture fraction. Maximum Sc alar D issipa tion is wher e flamelets e xtinguish a t lar ge sc alar dissipa tion (mixing) r ates.To pr event excessiv e mixing in the flamelet , ANSY S Fluen t allo ws you t o sp ecify a Maximum Sc alar D issipa tion rate for the 1D flamelet equa tions . A reasonable v alue f or this is the st eady flamelet e xtinc tion sc alar dissipa tion. The default v alue 1719Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Calcula ting the F lameletsof 30/s is near the st eady extinc tion sc alar dissipa tion of a methane-air flame a t standar d temp erature and pr essur e. Cour ant Numb er is the numb er at which ANSY S Fluen t aut oma tically selec ts the time st ep f or the pr obabilit y equa tion based on this c onvective Courant numb er. Numb er of F lamelets is the numb er of unst eady laminar flamelets t o be initia ted in the simula tion. The pr obabilit y mar ker equa tion will b e solv ed f or each flamelet. Click Initializ e Unstead y Flamelet P robabilit y to initializ e the unst eady flamelet and its pr obabilit y mar ker equa tion. ANSY S Fluen t is no w ready for p ostpr ocessing the 1D unst eady flamelet and the 2D/3D unst eady mar ker pr obabilit y equa tion. 16.6.3. Saving the F lamelet D ata The flamelet tables ma y be wr itten t o a file f or imp ort into later sessions of ANSY S Fluen t.You ma y want to do this , for e xample , to change the numb er of discr etiza tion p oints in the PDF table , or t o plot the flamelet pr ofiles in ANSY S Fluen t.The flamelet tables should b e sa ved b efore you cr eate the PDF table: File → Write → Flamelet ... 16.6.4. Postpr ocessing the F lamelet D ata For the flamelet mo del, you c an displa y or wr ite flamelet cur ves. Click the Displa y Flamelets ... or Displa y Unstead y Flamelet ... butt on. If you ha ve a single flamelet , as f or the unst eady diffusion flamelet mo del, you c an acc ess the Flamelet 2D C urves dialo g box (Figur e 16.18: The F lamelet 2D curves D ialog Box (p.1720 )). Figur e 16.18: The F lamelet 2D cur ves D ialo g Box For the st eady diffusion flamelet mo del with mor e than one flamelet , you c an displa y 2D plots and 3D sur faces sho wing the v ariation of sp ecies fr action or t emp erature with the mean mix ture fraction or sc alar dissipa tion using the Flamelet 3D S urfaces dialo g box (for e xample ,Figur e 16.19: The Flamelet 3D Sur faces D ialog Box (p.1721 )). To acc ess this dialo g box, click the Displa y Flamelets ... butt on in the Flamelet tab of the Species Model dialo g box, as sho wn in Figur e 16.16: The S pecies M odel D ialog Box (Flamelet Tab) (p.1717 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1720Modeling N on-P remix ed C ombustionFigur e 16.19: The F lamelet 3D S urfaces D ialo g Box To displa y the flamelet tables gr aphic ally, use the f ollowing pr ocedur e: 1.In the Flamelet 3D S urfaces dialo g box, from the Plot Variable drop-do wn list , selec t the v ariable y ou want to displa y gr aphic ally. 2.Specify the Plot Type as either 3D S urface or 2D C urve on 3D S urface. •For a 3D sur face, enable or disable Draw N umb ers B ox under Options .When this option is tur ned on, the displa y will include a wir eframe b ox with the numer ical limits in each c oordina te dir ection. •For a 2D cur ve on a 3D sur face: a.Specify whether y ou w ant to wr ite the plot da ta to a file b y toggling Write To File under Options . b.Specify the X-A xis F unc tion against which the plot v ariable will b e displa yed b y selec ting Scalar Dissipa tion ( ), or Mixture Fraction ( ).The v ariable tha t is not selec ted will b e held c onstan t. c.Specify the t ype of discr etiza tion (tha t is, how the flamelet da ta will b e slic ed) f or the v ariable tha t is being held c onstan t (under Constan t Value of M ixture Fraction or Constan t Value of Sc alar Dissipa tion ). –If you selec ted Inde x under Slice by, specify the discr etiza tion Inde x of the v ariable tha t is b eing held c onstan t.The r ange of in teger v alues tha t you ar e allo wed t o cho ose fr om is displa yed under Min and Max, and is equiv alen t to the numb er of p oints sp ecified f or tha t variable in the Flamelet tab of the Species M odel dialo g box (see Calcula ting the F lamelets (p.1716 )). –If you selec ted Value under Slice by, specify the numer ical Value of the v ariable tha t is b eing held c onstan t.The r ange of v alues tha t you c an sp ecify is displa yed under Min and Max. 1721Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Calcula ting the F lamelets3.Write or displa y the flamelet table r esults . If you ha ve tur ned on the Write To File option f or a 2D plot , click Write and sp ecify a name f or the file in The S elec t File D ialog Box (p.569). Other wise , click Plot or Displa y as appr opriate to displa y a 2D plot or 3D sur face in the gr aphics windo w. Figur e 16.20: Example 2D P lot of F lamelet D ata (p.1722 ) and Figur e 16.21: Example 3D P lot of F lamelet Data (p.1723 ) sho w examples of a 2D cur ve plot and 3D sur face plot of a flamelet table . Figur e 16.20: Example 2D P lot of F lamelet D ata Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1722Modeling N on-P remix ed C ombustionFigur e 16.21: Example 3D P lot of F lamelet D ata 16.7. Calcula ting the L ook-U p Tables ANSY S Fluen t requir es additional inputs tha t are used in the cr eation of the lo ok-up tables . Several of these inputs c ontrol the numb er of discr ete values f or which the lo ok-up tables will b e comput ed.These paramet ers ar e input in the Table tab of the Species M odel dialo g box.When Automa ted G rid Refine- men t is enabled , you will sp ecify the table par amet ers displa yed in Figur e 16.22: The S pecies M odel Dialog Box (Table) Tab D ispla ying A utoma ted G rid R efinemen t (p.1724 ). If Automa ted G rid Refinemen t is disabled , you will sp ecify the table par amet ers displa yed in Figur e 16.23: The S pecies M odel D ialog Box (Table) Tab Ex cluding A utoma ted G rid R efinemen t (p.1725 ). Note Automa ted G rid Refinemen t is not a vailable with t wo mix ture fractions . 1723Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Calcula ting the L ook-U p TablesFigur e 16.22: The S pecies M odel D ialo g Box (Table) Tab D ispla ying A utoma ted G rid Refinemen t The lo ok-up table par amet ers when Automa ted G rid Refinemen t is enabled ar e as f ollows: Initial N umb er of G rid P oints specifies the numb er of gr id p oints for the r esolution of the mean mix ture fraction, mix ture fraction v arianc e, and mean en thalp y (for non-adiaba tic sy stems). Maximum N umb er of G rid P oints specifies the maximum numb er of gr id p oints used f or tabula tion. The gr id refinemen t procedur e will st op inser ting the p oints when either the change in v alue and slop e between succ essiv e points is within t oler ance or the maximum numb er of gr id p oints ar e gener ated. Maximum C hange in Value R atio specifies the maximum allo wable change in v alue of table v ariables b etween succ essiv e gr id p oints as specified b y Equa tion 8.28 in the Theor y Guide . Maximum C hange in S lope Ratio specifies the maximum change in the slop e of table v ariables b etween succ essiv e gr id p oints as sp ecified by Equa tion 8.29 in the Theor y Guide . Maximum N umb er of S pecies is the maximum numb er of sp ecies st ored in the lo okup tables . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1724Modeling N on-P remix ed C ombustionFigur e 16.23: The S pecies M odel D ialo g Box (Table) Tab E xcluding A utoma ted G rid Refinemen t The lo ok-up table par amet ers when Automa ted G rid Refinemen t is disabled ar e as f ollows: Numb er of M ean M ixture Fraction P oints is the numb er of discr ete values of at which the lo ok-up tables will b e comput ed. For a t wo-mix ture- fraction mo del, this v alue is the numb er of p oints in the instan taneous sta te pr ofile used t o comput e the PDF if y ou cho ose the PDF mo del (see Tuning the PDF P aramet ers f or Two-M ixture-Fraction C alcula- tions (p.1744 )). Incr easing the numb er of p oints will yield a mor e accur ate PDF shap e, but the c alcula tion will tak e longer .The mean mix ture fraction p oints will b e aut oma tically clust ered ar ound the st oichiometr ic mixture fraction v alue . Numb er of M ixture Fraction Varianc e Points is the numb er of discr ete values of at which the lo ok-up tables will b e comput ed. Lower resolution is acceptable b ecause the v ariation along the axis is , in gener al, slower than the v ariation along the axis of the lo ok-up tables .This option is a vailable only when no sec ondar y str eam has b een defined . Numb er of S econdar y M ixture Fraction P oints is the numb er of discr ete values of at which the lo ok-up tables will b e comput ed. Like the Numb er of M ean M ixture Fraction P oints, ANSY S Fluen t will use the Numb er of S econdar y M ixture Fraction Points to comput e the equilibr ium sta te-relation if y ou cho ose the PDF option (see Tuning the PDF Paramet ers f or Two-M ixture-Fraction C alcula tions (p.1744 )) for a t wo-mix ture-fraction mo del. A lar ger numb er of p oints will giv e a mor e accur ate shap e for the PDF , but with a longer c alcula tion time .This option is a vailable only when a sec ondar y str eam has b een defined . Maximum N umb er of S pecies is the maximum numb er of sp ecies tha t will b e included in the lo ok-up tables .The maximum numb er of species tha t can b e included is 200. ANSY S Fluen t will aut oma tically selec t the sp ecies with the lar gest mole fr actions t o include in the PDF table . Note tha t the PDF table v alues of densit y and sp ecific hea t are pre-calcula ted with all the sp ecies , and henc e the c onvergenc e behavior of ANSY S Fluen t will not b e aff ected 1725Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Calcula ting the L ook-U p Tablesby the input f or the Maximum N umb er of S pecies . Hence, to keep table siz es small, you should set the Maximum N umb er of S pecies to only include the sp ecies tha t you ar e interested in p ostpr ocessing . Numb er of M ean E nthalp y Points is the numb er of discr ete values of en thalp y at which the lo ok-up tables will b e comput ed.This input is requir ed only if y ou ar e mo deling a non-adiaba tic sy stem. The numb er of p oints requir ed will dep end on the chemic al sy stem tha t you ar e consider ing, with mor e points requir ed in high hea t release sy stems (f or example , hydrogen/o xygen flames). This option is not a vailable with the unst eady flamelet mo del. Minimum Temp erature is used t o det ermine the lo west t emp erature for which the lo ok-up tables ar e gener ated.Your input should correspond t o the minimum t emp erature expected in the domain (f or e xample , an inlet or w all temp erature). The minimum t emp erature should b e set 10–20 K b elow the minimum sy stem t emp erature.This option is available only if y ou ar e mo deling a non-adiaba tic sy stem. This option is not a vailable with the unst eady flamelet mo del. Include E quilibr ium F lamelet specifies tha t an equilibr ium flamelet (tha t is, ) will b e gener ated in ANSY S Fluen t and app ended t o the flamelet libr ary before the PDF table is c alcula ted.This option is a vailable when gener ating or imp orting multiple flamelets , as w ell as when a single flamelet is c onsider ed. In the la tter case, the PDF table will consist of t wo sc alar dissipa tion slic es, namely the equilibr ium slic e at , and the flamelet slic e.This option is a vailable only with the st eady diffusion flamelet mo del. When y ou ar e sa tisfied with y our inputs , click Calcula te PDF Table to gener ate the lo ok-up tables . The c omputa tions p erformed f or a single-mix ture-fraction c alcula tion culmina te in the discr ete in tegration of Equa tion 8.17 (or Equa tion 8.25 in the Theor y Guide ) as r epresen ted in Figur e 8.5: Logical D ependenc e of A veraged Sc alars on M ean M ixture Fraction, the M ixture Fraction Varianc e, and the C hemistr y Model (Adiaba tic, Single-M ixture-Fraction S ystems) (or Figur e 8.6: Logical D ependenc e of A veraged Sc alars on Mean M ixture Fraction, the M ixture Fraction Varianc e, Mean En thalp y, and the C hemistr y Model (N on- Adiaba tic, Single-M ixture-Fraction S ystems) in the Theor y Guide ). For a t wo-mix ture-fraction c alcula tion, ANSY S Fluen t will c alcula te the ph ysical pr operties using Equa tion 8.15 or its adiaba tic equiv alen t.The computa tion time will b e shor test f or adiaba tic single-mix ture-fraction equilibr ium c alcula tions and longest f or non-adiaba tic c alcula tions in volving multiple flamelet gener ation. Below, sample outputs are sho wn f or an adiaba tic single-mix ture-fraction equilibr ium c alcula tion and a non-adiaba tic c alcula tion with flamelets: Generating PDF lookup table Type of the PDF Table: Adiabatic Table (Two Streams) Calculating table ..... 1271 points calculated 22 species added PDF Table successfully generated! Generating PDF lookup table Type of the PDF Table: Nonadiabatic Table with Strained Flamelet Model (Two Streams) Calculating table ..... calculating temperature limits ..... calculating temperature limits ..... calculating scalar dissipation slices ..... - scalar dissipation slice 9 calculating equilibrium slice ..... Performing PDF integrations..... 16810 points calculated 17 species added Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1726Modeling N on-P remix ed C ombustion PDF Table successfully generated! Initializing PDF table arrays and structures. Imp ortant Note tha t ther e is a signific ant diff erence in r un time b etween the one-mix ture fraction model and the t wo-mix ture fraction mo del. In the one-mix ture fraction mo del, the PDF table contains the mean da ta of densit y, temp erature, and sp ecific hea ts, and is thr ee-dimensional for an equilibr ium nonadiaba tic c ase (mean mix ture fraction, mix ture fraction v arianc e, and mean hea t loss). For this c ase, ANSY S Fluen t up dates pr operties e very flo w it eration. In the case of the t wo-mix ture fraction mo del, only the instan taneous sta te relationships ar e stored and mean pr operties ar e calcula ted fr om these b y performing PDF in tegrations in e very cell of the ANSY S Fluen t simula tion. Since this is c omputa tionally e xpensiv e, ANSY S Fluen t provides the option of only up dating pr operties af ter a sp ecified numb er of it erations . For a t wo-mix ture fraction mo del, you c an also r efer to Full Tabula tion of the Two-M ixture- Fraction M odel (p.1727 ) for mor e inf ormation. After completing the c alcula tion a t the sp ecified numb er of mix ture fraction p oints, ANSY S Fluen t reports that the c alcula tion succ eeded . In a single-mix ture-fraction c ase, the r esulting lo ok-up tables tak e the form illustr ated in Figur e 8.8: Visual R epresen tation of a L ook-U p Table f or the Sc alar (M ean Value of Mass F ractions , Densit y, or Temp erature) as a F unction of M ean M ixture Fraction and M ixture Fraction Varianc e in A diaba tic S ingle-M ixture-Fraction S ystems in the Theor y Guide (or Figur e 8.10: Visual R epres- entation of a L ook-U p Table f or the Sc alar as a F unction of M ean M ixture Fraction and M ixture Fraction Varianc e and N ormaliz ed H eat Loss/G ain in N on-A diaba tic S ingle-M ixture-Fraction S ystems , for non- adiaba tic sy stems). These lo ok-up tables c an b e plott ed using the a vailable gr aphics t ools, as descr ibed in Postpr ocessing the L ook-U p Table D ata (p.1728 ). Note tha t in non-adiaba tic c alcula tions , the c onsole windo w will r eport tha t the t emp erature limits and enthalp y slic es ha ve been c alcula ted. For a t wo-mix ture-fraction c ase, the r esulting lo ok-up tables tak e the f orm illustr ated in Figur e 8.9: Visual Represen tation of a L ook-U p Table f or the Sc alar φ_I as a F unction of F uel M ixture Fraction and S econdar y Partial F raction in A diaba tic Two-M ixture-Fraction S ystems in the Theor y Guide (or Figur e 8.11: Visual Represen tation of a L ook-U p Table f or the Sc alar φ_I as a F unction of F uel M ixture Fraction and S econdar y Partial F raction, and N ormaliz ed H eat Loss/G ain in N on-A diaba tic Two-M ixture-Fraction S ystems , for non-adiaba tic sy stems). 16.7.1. Full Tabula tion of the Two-M ixture-Fraction M odel The default algor ithm f or the t wo-mix ture-fraction mo del is t o perform PDF in tegrations of the equi- librium sta te relationships a t run time . Since these ar e multi-dimensional in tegrals, the default t wo- mixture-fraction mo del c an b e computa tionally demanding . Alternatively, you ma y want to pr e-comput e these in tegrations and cr eate 4D lo ok-up tables f or adia- batic simula tions , or 5D tables f or non-adiaba tic simula tions . Such high-dimensional tables ar e compu- tationally e xpensiv e to build , and ma y requir e lar ge memor y and disk st orage, but c an off er substan tial impr ovemen t in r un time sp eed. The option t o cr eate a fully-tabula ted t wo-mix ture-fraction table is a vailable in c ases with the t wo- mixture-fraction mo del enabled , via the t ext command: 1727Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Calcula ting the L ook-U p Tablesdefine/models/species/full-tabulation? If you ar e mo deling p ollutan t formation, not e tha t the full tabula tion option is not c ompa tible with the mix ture-fr action option f or PDF M ode in the Turbulenc e In teraction M ode tab settings . See Setting Turbulenc e Paramet ers (p.1836 ) for details on Turbulenc e In teraction options f or p ollutan t modeling . 16.7.2. Stabilit y Issues in C alcula ting C hemic al E quilibr ium L ook-U p Tables Comple x chemistr y and non-adiaba tic eff ects ma y mak e the equilibr ium c alcula tion mor e time-c on- suming and difficult. In some instanc es the equilibr ium c alcula tion ma y even fail. You ma y be able t o elimina te an y difficulties tha t you enc oun ter b y trying the c alcula tion as an adiaba tic sy stem. Adiaba tic system c alcula tions ar e gener ally quit e str aigh tforward and c an pr ovide v aluable insigh t into the op- timal inputs t o the non-adiaba tic c alcula tion. Additional stabilit y issues ma y ar ise f or solid or hea vy liquid fuels tha t ha ve been defined using the empir ical fuel appr oach. You ma y find tha t, for rich fuel mix tures, the equilibr ium c alcula tion pr oduces very low temp eratures and e ventually fails .This indic ates tha t str ong endother mic r eactions ar e tak ing plac e and the mix ture is not able t o sustain them. In this situa tion, you ma y need t o raise the hea ting value of the fuel un til ANSY S Fluen t produces acc eptable r esults . Provided tha t your fuel will b e treated as a liquid or solid (c oal) fuel, you c an main tain the desir ed hea ting v alue in y our ANSY S Fluen t simu- lation. This is acc omplished b y defining the diff erence between the desir ed and the adjust ed hea ting values as la tent hea t (in the c ase of c ombusting solid fuel) or hea t of p yrolysis (in the c ase of liquid fuel). 16.7.3. Saving the L ook-U p Tables The lo ok-up tables ma y be stored in a file tha t you c an r ead back in to later sessions of ANSY S Fluen t. The lo ok-up tables should b e sa ved b efore you e xit fr om the cur rent ANSY S Fluen t session. File → Write → PDF ... By default , the file will b e sa ved as f ormatted (ASCII, or t ext).To sa ve a binar y (unf ormatted) file , turn on the Write Binar y Files option in the Selec t File dialo g box. 16.7.4. Postpr ocessing the L ook-U p Table D ata It is imp ortant for y ou t o view y our t emp erature and sp ecies tables t o ensur e tha t the y are adequa tely but not e xcessiv ely r esolv ed. Inadequa te resolution will lead t o inaccur acies , and e xcessiv e resolution will lead t o unnec essar ily slo w calcula tion times . After a PDF table has b een gener ated or r ead in to ANSY S Fluen t, you c an displa y 2D plots and 3D surfaces sho wing the v ariation of sp ecies mole fr action, densit y, or t emp erature with the mean mix ture fraction, mix ture fraction v arianc e, or en thalp y using the PDF Table dialo g box (for e xample ,Fig- ure 16.24: The PDF Table D ialog Box (N on-A diaba tic C ase With F lamelets) (p.1729 )).The PDF Table dialo g box can b e acc essed in one of t wo ways: •by click ing the Displa y PDF Table ... butt on in the Table tab of the Species M odel dialo g box (as sho wn in Figur e 16.23: The S pecies M odel D ialog Box (Table) Tab Ex cluding A utoma ted G rid R efinemen t (p.1725 )) •by using the f ollowing pa th: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1728Modeling N on-P remix ed C ombustionPostpr ocessing → Model S pecific → PDF Table ... Figur e 16.24: The PDF Table D ialo g Box (N on-A diaba tic C ase With F lamelets) To displa y the lo ok-up tables gr aphic ally, use the f ollowing pr ocedur e: 1.In the PDF Table dialo g box, in the Plot Variable drop-do wn list y ou c an selec t temp erature, densit y, or species mole fr action as the v ariable t o be plott ed. 2.(multiple flamelets only) S pecify the v alue of the Scalar D issipa tion . In the c ase of non-adiaba tic flamelets , ther e is the additional par amet er of mean en thalp y. In addition t o varying the mean en thalp y and mean mixture fraction, you c an v ary the displa y of the PDF table b y changing the v alue of the sc alar dissipa tion, which giv es the table a f ourth “dimension ”. 3.Specify the Plot Type as either 3D S urface or 2D C urve on 3D S urface. In the equilibr ium mo del, a 2D curve is a slic e of a 3D sur face, and ther efore some options selec ted f or a 3D sur face ma y impac t the displa y of a 2D cur ve. •For a 3D sur face: a.Enable or disable Draw N umb ers B ox under Options .When this option is tur ned on, the displa y will include a wir eframe b ox with the numer ical limits in each c oordina te dir ection. b.(non-adiaba tic c ases only) U nder Surface Paramet ers, specify the discr ete indep enden t variable to be held c onstan t in the lo ok-up table ( Constan t Value of ). 1729Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Calcula ting the L ook-U p Tables–For a single-mix ture-fraction c ase, selec t Scaled H eat Loss/G ain ( ),Mean M ixture Fraction ( ), or Scaled Varianc e ( ). For an y mean mix ture fraction , the v arianc e varies b etween a minimum of 0 and a maximum of . In or der t o view the mix ture fraction v arianc e, it is normaliz ed b y Equa tion 16.7 (p.1730 ) so tha t for an y mean mix ture fraction the sc aled v arianc e ranges fr om 0 t o 0.25. (16.7) –For a t wo-mix ture-fraction c ase, the Scaled H eat Loss/G ain is the only a vailable option. c.(non-adiaba tic c ases only) S pecify whether the 3D ar ray of da ta p oints available in the lo ok-up table will b e slic ed b y Inde x or Value under Slice by. –If you selec ted Inde x, specify the discr etiza tion Inde x of the v ariable tha t is b eing held c onstan t. The r ange of in teger v alues tha t you ar e allo wed t o cho ose fr om is displa yed under Min and Max, and is equiv alen t to the numb er of p oints sp ecified f or tha t variable in the Table tab of the Species Model dialo g box (see Calcula ting the L ook-U p Tables (p.1723 )). If you sp ecified t o hold the en thalp y (Scaled H eat Loss/G ain) constan t, the en thalp y slic e inde x corresponding t o the adiaba tic c ase will b e displa yed in the Adiaba tic field . –If you selec ted Value , specify the numer ical Value of the v ariable tha t is b eing held c onstan t.The range of v alues tha t you c an sp ecify is displa yed under Min and Max. •For a 2D cur ve on a 3D sur face: a.Specify whether y ou w ant to wr ite the plot da ta to a file b y toggling Write To File under Options . b.Under Curve Paramet ers, specify the X-A xis F unc tion against which the plot v ariable will b e dis- played. –For an adiaba tic single-mix ture-fraction c ase, selec t Mean M ixture Fraction ( ), or Scaled Varianc e ( ). –For a non-adiaba tic single-mix ture-fraction c ase, the options will dep end on wha t was selec ted under Constan t Value of under Surface Paramet ers, but will include t wo of the f ollowing: Scaled Heat Loss/G ain ( ),Mean M ixture Fraction , and Scaled Varianc e. –For a t wo-mix ture-fraction c ase, selec t Fuel M ixture Fraction ( ) or Secondar y Partial F raction ( ). c.Specify the t ype of discr etiza tion (tha t is, how the lo ok-up table da ta will b e slic ed) f or the v ariable that is b eing held c onstan t (under Constan t Value of M ean M ixture Fraction ,Constan t Value of Scaled Varianc e, and so on). Note tha t for non-adiaba tic c ases , each 3D sur face slic e contains a full set of 2D slic es. –If you selec ted Inde x under Slice by, specify the discr etiza tion Inde x of the v ariable tha t is b eing held c onstan t.The r ange of in teger v alues tha t you ar e allo wed t o cho ose fr om is displa yed under Min and Max, and is equiv alen t to the numb er of p oints sp ecified f or tha t variable in the Table tab of the Species M odel dialo g box (see Calcula ting the L ook-U p Tables (p.1723 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1730Modeling N on-P remix ed C ombustion–If you selec ted Value under Slice by, specify the numer ical Value of the v ariable tha t is b eing held c onstan t.The r ange of v alues tha t you c an sp ecify is displa yed under Min and Max. 4.Write or displa y the lo ok-up table r esults . If you ha ve tur ned on the Write To File option f or a 2D plot , click Write and sp ecify a name f or the file in The S elec t File D ialog Box (p.569). Other wise , click Plot or Displa y as appr opriate to displa y a 2D plot or 3D sur face in the gr aphics windo w. Figur e 16.25: Mean S pecies M ole F raction D erived F rom an E quilibr ium C hemistr y Calcula tion (p.1731 ) and Figur e 16.26: Mean Temp erature Derived F rom an E quilibr ium C hemistr y Calcula tion (p.1732 ) sho w examples of 2D plots der ived f or a v ery simple h ydrocarbon sy stem. Figur e 16.25: Mean S pecies M ole F raction D erived F rom an E quilibr ium C hemistr y Calcula tion 1731Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Calcula ting the L ook-U p TablesFigur e 16.26: Mean Temp erature D erived F rom an E quilibr ium C hemistr y Calcula tion Figur e 16.27: 3D P lot of L ook-U p Table f or Temp erature Gener ated f or a S imple H ydrocarbon S ys- tem (p.1732 ) sho ws an e xample of a 3D sur face der ived f or the same sy stem. Figur e 16.27: 3D P lot of L ook-U p Table f or Temp erature Gener ated f or a S imple H ydrocarb on System Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1732Modeling N on-P remix ed C ombustion16.8. Standar d Files f or D iffusion F lamelet M odeling The standar d flamelet file f ormat can b e used t o read and wr ite non-pr emix ed (diffusion) flamelets .The data str ucture for the standar d flamelet file f ormat is based on k eywords tha t precede each da ta sec tion. If an y of the k eywords in y our flamelet da ta file do not ma tch the supp orted k eywords, you will ha ve to manually edit the file and change the k eywords t o one of the supp orted t ypes. (The ANSY S Flu- ent flamelet filt er is c ase-insensitiv e, so y ou need not w orry ab out c apitaliza tion within the k eywords.) The f ollowing k eywords ar e supp orted b y the ANSY S Fluen t filt er: Keyword Descr iption HEADER Header sec tion BODY Main b ody sec tion NUMOFSPECIES Numb er of sp ecies GRIDPOINTS Numb er of gr id p oints PRESSURE Pressur e STRAINRATE Strain r ate for diffusion flamelet gener ated in physical spac e STOICH_SCADIS or CHI Stoichiometr ic sc alar dissipa tion f or diffusion flamelet STOICH_Z Stoichiometr ic mix ture fraction TEMPERATURE and TEMP Temp erature MASSFRACTION- Mass fr action Z Mixture fraction MOLEFRACTION- Mole fr action Note The str ain r ate output is wr itten if the flamelets ar e gener ated in ph ysical spac e, for e xample , using ANSY S CHEMKIN. 16.8.1. Sample S tandar d Diffusion F lamelet F ile A sample diffusion flamelet file in the standar d format is pr ovided b elow. Note tha t not all sp ecies ar e listed in this file . HEADER STOICH_SCADIS 1.000000E-02 NUMOFSPECIES 60 GRIDPOINTS 50 STOICH_Z 6.618652E-02 PRESSURE 1.013250E+05 BODY Z 0.000000000E+00 8.273315430E-03 1.240997314E-02 1.447830200E-02 1.551246643E-02 1.602954865E-02 1.654663086E-02 2.068328857E-02 2.481994629E-02 3.309326172E-02 4.136657715E-02 4.963989258E-02 5.377655029E-02 5.791320801E-02 6.204986572E-02 6.618652344E-02 6.912528540E-02 7.206404735E-02 7.500280931E-02 7.794157127E-02 7.867626176E-02 7.941095225E-02 8.088033323E-02 8.381909519E-02 8.675785714E-02 8.969661910E-02 9.263538106E-02 9.557414302E-02 1.014516669E-01 1.073291909E-01 1.132067148E-01 1.190842387E-01 1.249617626E-01 1.367168104E-01 1.425943343E-01 1.484718583E-01 1.543493822E-01 1.572881441E-01 1.602269061E-01 1.672799348E-01 1733Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Standar d Files f or D iffusion F lamelet M odeling 1.743329635E-01 1.884390209E-01 2.166511357E-01 2.448632505E-01 2.730753653E-01 3.407844408E-01 4.084935163E-01 5.709952975E-01 7.659974350E-01 1.000000000E+00 TEMPERATURE 3.000000000E+02 6.268546798E+02 7.802882604E+02 8.544333704E+02 8.908936814E+02 9.089771589E+02 9.269654154E+02 1.067550740E+03 1.203418117E+03 1.462664100E+03 1.707202552E+03 1.934669997E+03 2.037622483E+03 2.128475386E+03 2.200397351E+03 2.244572249E+03 2.254177637E+03 2.245072250E+03 2.220638695E+03 2.186735136E+03 2.177535664E+03 2.168109526E+03 2.148737393E+03 2.108856496E+03 2.068758176E+03 2.029154219E+03 1.990673114E+03 1.953782923E+03 1.885112633E+03 1.821857119E+03 1.761797286E+03 1.703540208E+03 1.647197627E+03 1.543457773E+03 1.496624533E+03 1.452642813E+03 1.410968313E+03 1.390849359E+03 1.371237774E+03 1.326602075E+03 1.286669965E+03 1.222176660E+03 1.134221753E+03 1.064763074E+03 1.004219101E+03 8.845385948E+02 7.871510772E+02 6.152847269E+02 4.605312740E+02 3.000000000E+02 massfraction-h 0.000000000E+00 8.470246609E-15 1.689876963E-13 7.823505733E-13 1.604836416E-12 2.259465253E-12 3.137901769E-12 2.297692554E-11 1.299314819E-10 2.009221085E-09 3.364446760E-08 4.504321512E-07 1.488600091E-06 4.041919731E-06 9.259044043E-06 1.764854561E-05 2.446982906E-05 2.948355957E-05 3.067005444E-05 2.858096141E-05 2.763204904E-05 2.660609671E-05 2.447858861E-05 2.024662524E-05 1.571691024E-05 1.207106883E-05 9.769042791E-06 8.144795604E-06 5.683704776E-06 3.862438419E-06 2.529575950E-06 1.577642294E-06 9.493198194E-07 3.597224020E-07 2.397461608E-07 1.672683885E-07 1.109095223E-07 8.352078253E-08 5.847760877E-08 2.024498078E-08 6.804126487E-09 1.241975019E-09 1.664800458E-10 3.824650210E-11 1.058872219E-11 1.103611172E-12 2.070333150E-13 5.521048377E-15 6.116361056E-17 0.000000000E+00 massfraction-o2 2.330000000E-01 2.037872969E-01 1.891809523E-01 1.818777426E-01 1.782261116E-01 1.764002861E-01 1.745744526E-01 1.599674402E-01 1.453586904E-01 1.161277458E-01 8.685446531E-02 5.764270922E-02 4.337649028E-02 2.986903537E-02 1.792882492E-02 8.656537748E-03 4.260825775E-03 1.718417261E-03 5.787962652E-04 1.809733781E-04 1.319197735E-04 9.626119601E-05 5.195145104E-05 1.624530279E-05 5.000207346E-06 1.625791857E-06 5.935574928E-07 2.314963476E-07 5.242565474E-08 1.388575920E-08 4.396692299E-09 1.701489188E-09 7.617025651E-10 3.172983452E-10 2.146818725E-10 1.500353242E-10 1.052693603E-10 8.680804793E-11 7.032480088E-11 3.785587351E-11 1.627110024E-11 1.631110236E-12 2.316226342E-14 1.904385354E-16 8.159316969E-19 2.851864505E-21 7.569901388E-23 1.016058744E-25 1.304158252E-26 0.000000000E+00 massfraction-oh . . . . . . . . . . . . . . . 16.8.2. Missing S pecies ANSY S Fluen t will check whether all sp ecies in the flamelet da ta file e xist in the ther modynamic properties da tabases thermo.db . If an y of the sp ecies in the flamelet file do not e xist, ANSY S Fluen t will issue an er ror message and halt the flamelet imp ort. If this o ccurs , you c an either add the missing species t o the da tabase , or r emo ve the sp ecies fr om the flamelet file . You should not r emo ve a sp ecies fr om the flamelet da ta file unless its sp ecies c oncentration is v ery small (10-3 or less) thr oughout the flamelet pr ofile . If you r emo ve a lo w-concentration sp ecies , you will not ha ve the sp ecies c oncentrations a vailable f or viewing in the ANSY S Fluen t calcula tion, but the ac- curacy of the ANSY S Fluen t calcula tion will other wise b e unaff ected. Imp ortant If you cho ose t o remo ve an y sp ecies , be sur e to also up date the numb er of sp ecies (k eyword NUMOFSPECIES ) in the flamelet da ta file , to reflec t the loss of an y sp ecies y ou ha ve remo ved from the file . If a sp ecies with r elatively lar ge c oncentration is missing fr om the ANSY S Fluen t ther modynamic databases , you will ha ve to add it. Remo ving a high-c oncentration sp ecies fr om the flamelet file is not recommended . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1734Modeling N on-P remix ed C ombustion16.9. Setting U p the Iner t Model This sec tion descr ibes ho w to set up and apply the iner t mo del. For a discussion ab out the theor y, refer to Using the N on-P remix ed M odel with the Iner t Model in the Theor y Guide . To enable the iner t mo del, mak e sur e tha t the non-pr emix ed or par tially pr emix ed mo del is selec ted in the Species M odel dialo g box, or tha t a PDF file is r ead. Refer to Steps in U sing the N on-P remix ed Model (p.1687 ) and Modeling P artially P remix ed C ombustion (p.1759 ) to lear n mor e ab out these mo dels . Setup → Models → Iner t Edit... Figur e 16.28: The Iner t Model D ialo g Box The Iner t dialo g box will b e displa yed ( Figur e 16.28: The Iner t Model D ialog Box (p.1735 )).To enable this model, selec t Iner t Transp ort.The f ollowing st eps will w alk y ou thr ough setting up the iner t mo del: 1.Selec t Fixed H/C R atio as the Comp osition Option if the h ydrogen t o carbon r atio is k nown. For e xample , for methane (CH4) enter 4 for H/C R atio. Setting the H/C r atio assumes tha t the bur ned gas r esult ed fr om the c omplet e, stoichiometr ic combustion of tha t hydrocarbon fuel with air , and the only pr oduc ts of the c ombustion ar e CO2, H2O and N2. 2.Selec t User S pecified as the Comp osition Option if you w ant to sp ecify an arbitr ary comp osition f or the iner t str eam, as sho wn in Figur e 16.29: The Iner t Model D ialog Box (p.1736 ). 1735Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the Iner t ModelFigur e 16.29: The Iner t Model D ialo g Box You c an sp ecify y our c omp osition str eam b y adding or r emo ving sp ecies if y our str eam is c omp osed of sp ecies other than the default sp ecies list. a.To add sp ecies t o the Species list, type the chemic al formula under Iner t Species and click Add. b.Enter the Mass F raction of the newly added sp ecies . Continue in this manner un til all of the iner t species you w ant to include ar e sho wn in the Species list. c.Make sur e the sum of the mass fr actions add up t o 1. ANSY S Fluen t will nor maliz e the sp ecies mass fractions f or y ou when y ou click Normaliz e Species . d.To remo ve a sp ecies fr om the list , type the chemic al formula under Iner t Species and click Remo ve. e.To pr int a list of all sp ecies in the ther modynamic da tabase file ( thermo.db ) in the c onsole windo w, click List A vailable S pecies . 16.9.1. Setting B oundar y Conditions f or Iner t Transp ort You will need t o set appr opriate boundar y conditions a t flo w inlets and e xits f or the iner t tracer mass fraction, .The tr acer sp ecies mass fr action must b e between z ero and one , with the v alue of one meaning tha t all of the ma terial en tering the domain c omes fr om the iner t str eam. The v alues f or flo w boundar ies ar e set in the Iner t Stream field of the inlet b oundar y condition dialo g boxes, under the Species tab . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1736Modeling N on-P remix ed C ombustion16.9.2. Initializing the Iner t Stream The main assumption of the iner t mo del is tha t the c omp osition of the iner t str eam do es not change with c ombustion. For some dilutan ts, this is a v ery reasonable assumption, however, it is not v alid f or rich c ombustion wher e ther e is fuel in the e xhaust str eam. For c ases wher e ther e is fuel or o xidiz er left in the e xhaust gas , the accur acy of y our r esults will dep end up on tak ing the fuel or o xidiz er sp ecies into acc oun t when setting initial c onditions . 16.9.2.1. Iner t Fraction Initializa tion of the iner t mass fr action is done in the same w ay as other v ariables: by en tering in the appr opriate value in the Solution Initializa tion task page . Another option f or initializa tion is t o patch the v alue of in a r egion of the domain. When the v alue of is pa tched in this w ay, ANSY S Fluen t aut oma tically r ecalcula tes the en thalp y field f or the cur rent temp erature field in or der t o acc oun t for the change in c omp osition. See Patching Values in S elec ted C ells (p.2607 ) for details ab out pa tching v alues of solution v ariables . 16.9.2.2. Iner t Comp osition For c ombustion c alcula tions tha t bur n a h ydrocarbon fuel, ANSY S Fluen t provides a str aigh tforward way of setting the initial c omp osition of the iner t str eam. The iner t comp osition c an b e set b y assuming a ratio of h ydrogen t o carbon in the f ollowing o verall o xida tion r eaction (fr om H eywood [47] (p.4007 )): (16.8) which c an b e rewritten in t erms of the r atio of h ydrogen t o carbon a toms ( ) in the fuel as (16.9) If Equa tion 16.9 (p.1737 ) is solv ed f or the mass fr actions of C O2, H2O and N2, the f ollowing r elations are obtained: (16.10) wher e Setting the H/C r atio assumes tha t the bur ned gas r esult ed fr om the c omplet e, stoichiometr ic com- bustion of tha t hydrocarbon fuel, and the only pr oduc ts of the c ombustion ar e CO2, H2O and N2. An arbitr ary comp osition f or the iner t str eam c an also b e sp ecified in the in terface. 16.9.3. Resetting Iner t EGR ANSY S Fluen t allo ws bur ned gases t o be converted t o an iner t gas .This has b een designed with in- cylinder c ombustion in mind t o aid the simula tion of multiple c ycles of such engines using the par tially- premix ed c ombustion mo del with e xhaust gas r ecircula tion (EGR). At the end of a c ombustion str oke, 1737Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the Iner t Modelthe pr emix ed pr ogress v ariable of the bur nt gases is unit y.When fr esh char ge, with pr ogress v ariable of zero, is mix ed with the bur nt trapp ed gases , combustion will b e initia ted unless these tr app ed gases are converted t o iner t. This facilit y is acc essed via the Dynamic M esh E vents dialo g box, as descr ibed in Resetting Iner t EGR (p.1345 ).There, you will need t o set the cr ank angle a t which the e vent occurs (usually shor tly b efore the inlet v alves op en) and a t the fluid z ones (usually the c ombustion chamb er) wher e the bur nt gases are converted t o iner t. When ANSY S Fluen t performs an iner t reset , the iner t comp osition is c alcula ted as the st oichiometr ic comp osition. For lean mix tures, the st oichiometr ic iner t is mix ed with o xidiz er, and f or rich mix tures the st oichiometr ic iner t is mix ed with fuel, so tha t overall st oichiometr y is c onser ved.This en tails: •Calcula ting the st oichiometr ic mix ture fraction, which is defined as the mix ture wher e both fuel and oxidiz er ar e complet ely c onsumed . •Calcula ting the iner t species mass fr actions as the st oichiometr ic sp ecies mass fr actions . Species with mole fr actions less than 0.01 ar e disc arded . •Setting the iner t mass fr action and the mix ture fraction as f ollows: –Lean mix tures –Rich mix tures wher e is the iner t mass fr action, is the mix ture fraction, is the r eaction pr ogress, sub- script sto denot es st oichiometr ic, subscr ipt old denot es v alues b efore iner t reset , tilde sup er- script denot es F avre averaging . •Setting the r eaction pr ogress t o zero. –For the ECFM mo del, flame ar ea densit y is set t o zero. –For the G-E qua tion mo del, G (the mean distanc e from the flame fr ont) is set t o a nega tive value . •Since ther e will b e some small er rors in the sp ecies mass fr actions fr om b efore the EGR r eset , the temp erature will change due t o the change in the sp ecific hea t. By default , ANSY S Fluen t adjusts the enthalp y so tha t temp erature is unchanged af ter EGR r eset. This ma y be limit ed b y the PDF table Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1738Modeling N on-P remix ed C ombustiontemp erature limits f or the new mix ture fraction, in which c ase the t emp erature after iner t reset will not equal the t emp erature before the iner t reset e vent. 16.10. Defining N on-P remix ed B oundar y Conditions For inf ormation ab out defining non-pr emix ed b oundar y conditions , see the f ollowing sec tions: 16.10.1. Input of M ixture Fraction B oundar y Conditions 16.10.2. Diffusion a t Inlets 16.10.3. Input of Thermal B oundar y Conditions and F uel Inlet Velocities 16.10.1. Input of M ixture Fraction B oundar y Conditions When the non-pr emix ed c ombustion mo del is used , flow b oundar y conditions a t inlets and e xits (tha t is, velocity or pr essur e, turbulenc e in tensit y) ar e defined in the usual w ay. Species mass fr actions a t inlets ar e not r equir ed. Inst ead, you define v alues f or the mean mix ture fraction, , and the mix ture fraction v arianc e, , at inlet b oundar ies. (For pr oblems tha t include a sec ondar y str eam, you will define b oundar y conditions f or the mean sec ondar y par tial fr action and its v arianc e as w ell as the mean fuel mix ture fraction and its v arianc e.) These inputs pr ovide b oundar y conditions f or the c onser- vation equa tions y ou will solv e for these quan tities .The inlet v alues ar e supplied in the b oundar y conditions task page , under the a vailable tabs , for the selec ted inlet b oundar y (for e xample ,Fig- ure 16.30: The Velocity Inlet D ialog Box Showing M ixture Fraction B oundar y Conditions (p.1739 )). Setup → Boundar y Conditions Figur e 16.30: The Velocity Inlet D ialo g Box Showing M ixture Fraction B oundar y Conditions Click the Species tab and sp ecify the Mean M ixture Fraction and Mixture Fraction Varianc e (and the Secondar y M ean M ixture Fraction and Secondar y M ixture Fraction Varianc e, if y ou ar e using two mix ture fractions). In gener al, the inlet v alue of the mean fr actions will b e 1.0 or 0.0 a t flo w inlets: the mean fuel mix ture fraction will b e 1.0 a t fuel str eam inlets and 0.0 a t oxidiz er or sec ondar y str eam inlets; the mean sec ondar y mix ture fraction will b e 1.0 a t sec ondar y str eam inlets and 0.0 a t fuel or oxidiz er inlets .The fuel or sec ondar y mix ture fraction will lie b etween 0.0 and 1.0 only if y ou ar e 1739Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Defining N on-P remix ed B oundar y Conditionsmodeling flue gas r ecycle, as illustr ated in Figur e 8.15: Using the N on-P remix ed M odel with F lue G as Recycle and discussed in Definition of the M ixture Fraction in the Theor y Guide .The fuel or sec ondar y mixture fraction v arianc e can usually b e tak en as z ero at inlet b oundar ies. 16.10.2. Diffusion a t Inlets In some c ases , you ma y want to include the diffusiv e transp ort of mix ture fraction thr ough the inlets of y our domain. You c an do this b y enabling inlet mix ture-fraction diffusion. By default , ANSY S Flu- ent excludes the diffusion flux of mix ture fraction a t inlets .To enable inlet diffusion, use either the define/models/ species/inlet-diffusion? text command , or the Species M odel dialo g box (Figur e 16.1: Defining E quilibr ium C hemistr y (p.1688 )) Setup → Models → Species Edit... and enable the Inlet D iffusion option. 16.10.3. Input of Thermal B oundar y Conditions and F uel Inlet Velocities If your mo del is non-adiaba tic, you should sp ecify the Temp erature at the flo w inlets . Recall tha t the inlet t emp eratures w ere request ed dur ing the table c onstr uction in the Chemistr y tab of the Species Model dialo g box, and w ere used in the c onstr uction of the lo ok-up tables .The inlet t emp eratures for each fuel, oxidiz er, and sec ondar y inlet in y our non-adiaba tic mo del should b e defined , in addition, as b oundar y conditions in ANSY S Fluen t. It is acc eptable f or the inlet t emp erature boundar y conditions to diff er sligh tly fr om those y ou input f or the lo ok-up table c alcula tions . If the inlet t emp eratures diff er signific antly fr om those in the Chemistr y tab , however, your lo ok-up tables ma y pr ovide inaccur ate interpolation. This is b ecause the discr ete points in the lo ok-up tables w ere clust ered ar ound a finit e range of the t emp eratures defined in the Chemistr y tab , and y our input in the ANSY S Fluen t inlet boundar y condition ma y fall outside this r ange . Wall ther mal b oundar y conditions should also b e defined f or non-adiaba tic non-pr emix ed c ombustion calcula tions .You c an use an y of the standar d conditions a vailable in ANSY S Fluen t, including sp ecified wall t emp erature, hea t flux, external hea t transf er coefficien t, or e xternal r adia tion. If radia tion is t o be included within the domain, the w all emissivit y should b e defined as w ell. See Thermal B oundar y Conditions a t Walls (p.984) for details ab out ther mal b oundar y conditions a t walls. 16.11. Defining N on-P remix ed P hysical P roperties When y ou use the non-pr emix ed c ombustion mo del, the ma terial used f or all fluid z ones is aut oma tically set t o pdf-mix ture.This ma terial is a sp ecial c ase of the mix ture ma terial c oncept discussed in Mixture Materials (p.1615 ).The c onstituen t sp ecies of this mix ture ar e the sp ecies tha t were calcula ted in the PDF look-up table cr eation; you c annot change them dir ectly.When the non-pr emix ed mo del is used , hea t capacities , molecular w eigh ts, and en thalpies of f ormation f or each sp ecies c onsider ed ar e extracted from the chemic al da tabase , so y ou will not mo dify an y pr operties f or the c onstituen t sp ecies in the PDF mix ture. For the PDF mix ture itself , the mean densit y and mean sp ecific hea t are det ermined fr om the lo ok-up tables . The ph ysical pr operty inputs f or a non-pr emix ed c ombustion pr oblem ar e ther efore only the tr ansp ort properties (visc osity, ther mal c onduc tivit y, and so on) f or the PDF mix ture.To set these in the Create/Edit Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1740Modeling N on-P remix ed C ombustionMaterials D ialog Box (p.3386 ), cho ose mix ture as the Material Type,pdf-mix ture (the default , and only choic e) in the Mixture M aterials list, and set the desir ed v alues f or the tr ansp ort properties. Setup → Materials See Physical Properties (p.1079 ) for details ab out setting ph ysical pr operties.The tr ansp ort properties in a non-pr emix ed c ombustion pr oblem c an b e defined as func tions of t emp erature, if desir ed, but not as func tions of c omp osition. In pr actice, sinc e turbulenc e eff ects will domina te, it will b e of little b enefit to include e ven the t emp erature dep endenc e of the laminar tr ansp ort properties. If you ar e mo deling r adia tion hea t transf er, you will also en ter radia tion pr operties, as descr ibed in Ra- diation P roperties (p.1137 ). Comp osition-dep enden t absor ption c oefficien ts (using the WSGGM) ar e allo wed. The non-pr emix ed mo del c an also b e used with r eal gas mo dels in ANSY S Fluen t, if the Compr essibilit y Effects option is enabled in the Species M odel dialo g box. In this c ase, the densit y metho d is based on one of the f our r eal gas mo dels , discussed in Equa tion of S tate (p.1159 ) and Using the C ubic E qua tion of S tate Real G as M odels (p.1165 ). 16.12. Solution S trategies f or N on-P remix ed M odeling The non-pr emix ed mo del setup and solution pr ocedur e in ANSY S Fluen t diff ers sligh tly f or single- and two-mix ture-fraction pr oblems . Below, an o verview of each appr oach is pr ovided . Note tha t your ANSY S Fluen t case file must alw ays meet the r estrictions list ed f or the non-pr emix ed mo deling appr oach in Restrictions on the M ixture Fraction A pproach in the Theor y Guide . In this sec tion, details ar e pr ovided regar ding the pr oblem definition and c alcula tion pr ocedur es y ou f ollow in ANSY S Fluen t. For additional inf ormation, see the f ollowing sec tions: 16.12.1. Single-M ixture-Fraction A pproach 16.12.2. Two-M ixture-Fraction A pproach 16.12.3. Starting a N on-P remix ed C alcula tion F rom a P revious C ase F ile 16.12.4. Solving the F low Problem 16.12.1. Single-M ixture-Fraction A ppr oach For a single-mix ture-fraction sy stem, when y ou ha ve complet ed the c alcula tion of the PDF lo ok-up tables , you ar e ready to begin y our r eacting flo w simula tion. In ANSY S Fluen t, you will solv e the flo w field and pr edic t the spa tial distr ibution of and (and if the sy stem is non-adiaba tic or if the system is based on laminar flamelets). ANSY S Fluen t will obtain the c orresponding v alues of t emp erature and individual chemic al sp ecies mass fr actions fr om the lo ok-up tables . 16.12.2. Two-M ixture-Fraction A ppr oach When a sec ondar y str eam is included , ANSY S Fluen t will solv e transp ort equa tions f or the mean sec- ondar y par tial fr action ( ) and its v arianc e in addition t o the mean fuel mix ture fraction and its varianc e. ANSY S Fluen t will then lo ok up the instan taneous v alues f or temp erature, densit y, and indi- vidual chemic al sp ecies in the lo ok-up tables , comput e the PDFs f or the fuel and sec ondar y str eams , and c alcula te the mean v alues f or temp erature, densit y, and sp ecies . Note tha t in or der t o avoid b oth inaccur acies and unnec essar ily slo w calcula tion times , it is imp ortant for y ou t o view y our t emp erature and sp ecies tables in ANSY S Fluen t to ensur e tha t the y are adequa tely but not e xcessiv ely r esolv ed. 1741Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Solution S trategies f or N on-P remix ed M odeling16.12.3. Starting a N on-P remix ed C alcula tion F rom a P revious C ase F ile You c an r ead a pr eviously defined ANSY S Fluen t case file as a star ting p oint for y our non-pr emix ed combustion mo deling . If this c ase file c ontains inputs tha t are inc ompa tible with the cur rent non- premix ed c ombustion mo del, ANSY S Fluen t will aler t you when the non-pr emix ed mo del is tur ned on and it will tur n off those inc ompa tible mo dels . For e xample , if the c ase file includes sp ecies tha t diff er from those included in the PDF file cr eated b y ANSY S Fluen t, these sp ecies will b e disabled . If the c ase file c ontains pr operty descr iptions tha t conflic t with the pr operty da ta in the chemic al da tabase , these property inputs will b e ignor ed. Imp ortant PDF files cr eated b y pr ePDF 2 or older ar e not supp orted b y this v ersion of ANSY S Fluen t. The files gener ated b y PrePDF v ersion 3 or new er, are fully c ompa tible . In the Species M odel dialo g box, selec t Non-P remix ed C ombustion under the Model heading .When you click OK in the Species M odel dialo g box,The S elec t File D ialog Box (p.569) will immedia tely app ear, prompting y ou f or the name of the PDF file c ontaining the lo ok-up tables cr eated in a pr evious ANSY S Fluen t session. (The PDF file is the file y ou sa ved using the File/W rite/PDF ... ribbon tab it em af ter computing the lo ok-up tables .) ANSY S Fluen t will indic ate tha t it has succ essfully r ead the sp ecified PDF file: Reading "/home/mydirectory/adiabatic.pdf"... read 5 species (binary c, adiabatic fluent) pdf file successfully read. Done. After y ou r ead in the PDF file , ANSY S Fluen t will inf orm y ou tha t some ma terial pr operties ha ve changed . You c an acc ept this inf ormation; you will b e up dating pr operties la ter on. You c an r ead in an alt ered PDF file a t an y time b y using the File/Read/PDF ... ribbon tab it em. Imp ortant Recall tha t the non-pr emix ed c ombustion mo del is a vailable only when y ou used the pr es- sure-based solv er; it c annot b e used with the densit y-based solv ers. Also, the non-pr emix ed combustion mo del is a vailable only when turbulenc e mo deling is ac tive. If you ar e mo deling a non-adiaba tic sy stem and y ou w ant to include the eff ects of c ompr essibilit y, re- open the Species M odel dialo g box and tur n on Compr essibilit y Effects under PDF Options .This option t ells ANSY S Fluen t to up date the densit y acc ording t o Equa tion 16.1 (p.1693 ).When the non- premix ed c ombustion mo del is ac tive, you c an enable c ompr essibilit y eff ects only in the Species Model dialo g box. For other mo dels , you will sp ecify c ompr essible flo w (ideal-gas ,boussinesq , and so on) in the Create/Edit M aterials dialo g box. See Specifying the Op erating P ressur e for the S ys- tem (p.1693 ) and Tuning the PDF P aramet ers f or Two-M ixture-Fraction C alcula tions (p.1744 ) for mor e information ab out c ompr essibilit y eff ects. 16.12.3.1. Retrie ving the PDF F ile D uring C ase F ile R eads The PDF filename is sp ecified t o ANSY S Fluen t only onc e.Thereafter, the filename is st ored in y our ANSY S Fluen t case file and the PDF file will b e aut oma tically r ead in to ANSY S Fluen t whene ver the Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1742Modeling N on-P remix ed C ombustioncase file is r ead. ANSY S Fluen t will r emind y ou tha t it is r eading the PDF file af ter it finishes r eading the r est of the c ase file b y reporting its pr ogress in the t ext (console) windo w. Note tha t the PDF filename st ored in y our c ase file ma y not c ontain the full name of the dir ectory in which the PDF file e xists .The full dir ectory name will b e stored in the c ase file only if y ou initially read the PDF file thr ough the GUI (or if y ou t yped in the dir ectory name along with the filename when using the t ext interface). In the e vent tha t the full dir ectory name is absen t, the aut oma tic reading of the PDF file ma y fail (sinc e ANSY S Fluen t do es not k now which dir ectory to lo ok in f or the file), and y ou will need t o manually sp ecify the PDF file .The saf est appr oaches ar e to use the GUI when y ou first r ead the PDF file or t o supply the full dir ectory name when using the t ext interface. 16.12.4. Solving the F low P roblem The ne xt step in the non-pr emix ed c ombustion mo deling pr ocess in ANSY S Fluen t is the solution of the mix ture fraction and flo w equa tions . First, initializ e the flo w. By default , the mix ture fraction and its v arianc e ha ve initial v alues of z ero, which is the r ecommended v alue; you should gener ally not set nonz ero initial v alues f or these v ariables . See Initializing the S olution (p.2604 ) for details ab out solution initializa tion. Solution → Initializa tion Next, begin c alcula tions in the usual manner . Solution → Run C alcula tion During the c alcula tion pr ocess, ANSY S Fluen t reports residuals f or the mix ture fraction and its v arianc e in the fmean and fvar columns of the r esidual r eport: iter cont x-vel y-vel k epsilon fmean fvar 28 1.57e-3 4.92e-4 4.80e-4 2.68e-2 2.59e-3 9.09e-1 1.17e+0 29 1.42e-3 4.43e-4 4.23e-4 2.48e-2 2.30e-3 8.89e-1 1.15e+0 30 1.28e-3 3.98e-4 3.75e-4 2.29e-2 2.04e-3 8.88e-1 1.14e+0 (For two-mix ture-fraction c alcula tions , columns f or psec and pvar will also app ear.) 16.12.4.1. Under -Relaxation F actors for PDF E quations The tr ansp ort equa tions f or the mean mix ture fraction and mix ture fraction v arianc e ar e quit e stable and high, under-r elaxa tion c an b e used when solving them. By default , an under-r elaxa tion fac tor of 1 is used f or the mean mix ture fraction (and sec ondar y par tial fr action) and 0.9 f or the mix ture fraction varianc e (and sec ondar y par tial fr action v arianc e). If the r esiduals f or these equa tions ar e incr easing , you should c onsider decr easing these under-r elaxa tion fac tors, as discussed in Setting U nder-R elaxa tion Factors (p.2573 ). 16.12.4.2. Densit y Under -Relaxation One of the main r easons a c ombustion c alcula tion c an ha ve difficult y converging is tha t lar ge changes in temp erature cause lar ge changes in densit y, which c an, in tur n, cause instabilities in the flo w solution. ANSY S Fluen t allo ws you t o under-r elax the change in densit y to alle viate this difficult y.The default v alue f or densit y under-r elaxa tion is 1, but if y ou enc oun ter convergenc e trouble y ou ma y want to reduc e this t o a v alue b etween 0.5 and 1 (in the Solution C ontrols task page). 1743Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Solution S trategies f or N on-P remix ed M odelingNote tha t if y ou ar e using a r eal-gas mo del the solution migh t converge a t a slo wer rate than when running ideal-gas flo w.To impr ove the c onvergenc e performanc e of y our analy sis, you need t o reduc e the under relaxa tion f or densit y to values as lo w as 0.1. 16.12.4.3. Tuning the PDF P aramet ers for Two-M ixture-Fraction C alculations For c ases tha t include a sec ondar y str eam, the PDF in tegrations ar e performed inside ANSY S Fluen t. The par amet ers f or these in tegrations ar e defined in the Species M odel D ialog Box (p.3294 ) (Fig- ure 16.31: The S pecies M odel D ialog Box for a Two-M ixture-Fraction C alcula tion (p.1744 )). Setup → Models → Species Edit... Figur e 16.31: The S pecies M odel D ialo g Box for a Two-M ixture-Fraction C alcula tion The par amet ers ar e as f ollows: Compr essibilit y Effects (non-adiaba tic sy stems only) t ells ANSY S Fluen t to up date the densit y, temp erature, species mass fr action, and en thalp y from the PDF tables t o acc oun t for the v arying pr essur e of the sy stem. 16.13. Postpr ocessing the N on-P remix ed M odel Results The final st ep in the non-pr emix ed c ombustion mo deling pr ocess is the p ostpr ocessing of sp ecies concentrations and t emp erature da ta fr om the mix ture fraction and flo w-field solution da ta.The f ollowing variables ar e of par ticular in terest: •Mean M ixture Fraction (in the Pdf... categor y) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1744Modeling N on-P remix ed C ombustion•Secondar y M ean M ixture Fraction (in the Pdf... categor y) •Mixture Fraction Varianc e (in the Pdf... categor y) •Secondar y M ixture Fraction Varianc e (in the Pdf... categor y) •Fvar P rod (in the Pdf... categor y, which is the pr oduc tion t erm in the mix ture fraction v arianc e transp ort equa tion) •Fvar2 P rod (in the Pdf... categor y) •Scalar D issipa tion (in the Pdf... categor y) •PDF Table A diaba tic E nthalp y (in the Pdf... categor y) •PDF Table H eat Loss/G ain (in the Pdf... categor y) •Mass fr action of species-n (in the Species ... categor y) •Mole fr action of species-n (in the Species ... categor y) •Molar C onc entration of species-n (in the Species ... categor y) •RMS species-n Mass F raction (in the Species ... categor y) •Static Temp erature (in the Temp erature... categor y) •RMS Temp erature (in the Temp erature... categor y) •Enthalp y (in the Temp erature... categor y) •Probabilit y (in the Unstead y Flamelet ... categor y) •Mean Temp erature (in the Unstead y Flamelet ... categor y) •Mean M ass F raction of species-n (in the Unstead y Flamelet ... categor y) Imp ortant For the unst eady diffusion flamelet mo del, mean sp ecies mass fr actions ar e displa yed f or the first fif ty sp ecies in the flamelet k inetic mechanism. These quan tities c an b e selec ted f or displa y in the indic ated c ategor y of the v ariable-selec tion dr op- down list tha t app ears in p ostpr ocessing dialo g boxes. See Field F unction D efinitions (p.2959 ) for their definitions . In all c ases , the sp ecies c oncentrations ar e der ived fr om the mix ture fraction/v arianc e field using the look-up tables . Note tha t temp erature and en thalp y can b e postpr ocessed e ven when y our ANSY S Fluen t model is an adiaba tic non-pr emix ed c ombustion simula tion in which y ou ha ve not solv ed the ener gy equa tion. In b oth the adiaba tic and non-adiaba tic c ases , the t emp erature is der ived fr om the lo ok-up table . Figur e 16.32: Predic ted C ontours of M ixture Fraction in a M ethane D iffusion F lame (p.1746 ) and Fig- ure 16.33: Predic ted C ontours of C O2 M ass F raction U sing the N on-P remix ed C ombustion M odel (p.1746 ) illustr ate typic al results f or a methane diffusion flame mo deled using the non-pr emix ed appr oach. 1745Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Postpr ocessing the N on-P remix ed M odel R esultsFigur e 16.32: Predic ted C ontours of M ixture Fraction in a M ethane D iffusion F lame Figur e 16.33: Predic ted C ontours of C O2 M ass F raction U sing the N on-P remix ed C ombustion Model For additional inf ormation, see the f ollowing sec tion: 16.13.1. Postpr ocessing f or Iner t Calcula tions 16.13.1. Postpr ocessing f or Iner t Calcula tions ANSY S Fluen t provides se veral additional r eporting options f or p ost-pr ocessing c alcula tions with the iner t mo del. You c an gener ate gr aphic al plots or alphanumer ic reports of the same it ems tha t are available with the non-pr emix ed or par tially pr emix ed mo dels , and in addition the f ollowing v ariables are available: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1746Modeling N on-P remix ed C ombustion•Iner t Mass F raction •Iner t Specific H eat •Iner t Densit y •Iner t Enthalp y •Pdf E nthalp y •Pdf Fmean •Pdf Fv ar •Mass F raction of Iner t wher e the mass fr action of the th iner t sp ecies , , is c alcula ted as wher e is the iner t tracer and is the mass fr action of the th iner t sp ecies defined in the Iner t dialo g box. Note these v ariables app ear in the Iner t... categor y. 1747Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Postpr ocessing the N on-P remix ed M odel R esultsRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1748Chapt er 17: Modeling P remix ed C ombustion This chapt ers discusses ho w to simula te pr emix ed turbulen t combustion in ANSY S Fluen t. For theor et- ical back ground on this mo del, see Premix ed C ombustion in the Theor y Guide . Information ab out using this mo del is pr ovided in the f ollowing sec tions: 17.1. Limita tions of the P remix ed C ombustion M odel 17.2. Using the P remix ed C ombustion M odel 17.3. Setting U p the C-E qua tion and G-E qua tion M odels 17.4. Setting U p the Ex tended C oher ent Flame M odel 17.5. Postpr ocessing f or P remix ed C ombustion C alcula tions 17.1. Limita tions of the P remix ed C ombustion M odel The f ollowing limita tions apply t o the pr emix ed c ombustion mo del: •You must use the pr essur e-based solv er.The pr emix ed c ombustion mo del is not a vailable with the densit y- based solv er. •The pr emix ed c ombustion mo del is v alid only f or turbulen t, subsonic flo ws.These t ypes of flames ar e called deflagr ations . Explosions , also c alled det ona tions , wher e the c ombustible mix ture is ignit ed b y the hea t behind a sho ck w ave, can b e mo deled with the finit e-rate mo del using the densit y-based solv er. See Mod- eling S pecies Transp ort and F inite-Rate Chemistr y (p.1613 ) for inf ormation ab out the finit e-rate mo del. •The pr emix ed c ombustion mo del c annot b e used in c onjunc tion with the p ollutan t (tha t is, soot and NO x) models . However, a perfectly pr emix ed sy stem c an b e mo deled with the par tially pr emix ed mo del (see Modeling P artially P remix ed C ombustion (p.1759 )), which c an b e used with the p ollutan t mo dels . •You c annot use the pr emix ed c ombustion mo del t o simula te reacting discr ete-phase par ticles , because these w ould r esult in a par tially pr emix ed sy stem. Only iner t par ticles c an b e used with the pr emix ed c om- bustion mo del. •The G-E qua tion mo del c an b e used only with the unst eady solv er b ecause it tr acks the flame fr ont in time . However, RANS solutions , which t end t o a st eady-sta te, can b e mo deled b y evolving them in time un til the solution is sta tionar y. 17.2. Using the P remix ed C ombustion M odel The pr ocedur e for setting up and solving a pr emix ed c ombustion mo del is outlined b elow, and then descr ibed in detail. Rememb er tha t only the st eps tha t are pertinen t to pr emix ed c ombustion mo deling are sho wn her e. For inf ormation ab out inputs r elated t o other mo dels tha t you ar e using in c onjunc tion with the pr emix ed c ombustion mo del, see the appr opriate sec tions f or those mo dels . 1749Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.1. Enable the pr emix ed turbulen t combustion mo del and set the r elated par amet ers. Note Make sur e a turbulenc e mo del (other than the S palar t-Allmar as mo del) is selec ted b efore selec ting a c ombustion mo del. Setup → Models → Species Edit... 2. Define the ph ysical pr operties f or the unbur nt and bur nt ma terial in the domain. Setup → Materials → Create/Edit... 3. Set the v alue of the pr ogress v ariable at flo w inlets and e xits. Setup → Boundar y Conditions 4. Initializ e and pa tch the v alue of the pr ogress v ariable . Solution → Initializa tion → Patch... 5. Solve the pr oblem and p erform p ostpr ocessing . Imp ortant If you ar e in terested in c omputing the c oncentrations of individual sp ecies in the domain, you c an use the par tially pr emix ed mo del descr ibed in Modeling P artially P remix ed C ombus- tion (p.1759 ). Alternatively, comp ositions of the unbur nt and bur nt mix tures c an b e obtained from e xternal analy ses using equilibr ium or k inetic c alcula tions . For additional inf ormation, see the f ollowing sec tions: 17.2.1. Enabling the P remix ed C ombustion M odel 17.2.2. Choosing an A diaba tic or N on-A diaba tic M odel 17.2.1. Enabling the P remix ed C ombustion M odel To enable the pr emix ed c ombustion mo del, selec t Premix ed C ombustion under Model in the Species Model D ialog Box (p.3294 ) (Figur e 17.1: The S pecies M odel D ialog Box for P remix ed C ombustion (p.1751 )). Setup → Models → Species Edit... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1750Modeling P remix ed C ombustionFigur e 17.1: The S pecies M odel D ialo g Box for P remix ed C ombustion When y ou enable Premix ed C ombustion , the dialo g box expands t o sho w the r elevant inputs . 17.2.2. Choosing an A diaba tic or N on-A diaba tic M odel Under Premix ed C ombustion M odel Options in the Species M odel D ialog Box (p.3294 ), cho ose either Adiaba tic (the default) or Non-A diaba tic.This choic e aff ects only the c alcula tion metho d used t o determine the t emp erature (either Equa tion 9.66 or Equa tion 9.67 in the Theor y Guide ). 17.3. Setting U p the C-E qua tion and G-E qua tion M odels When C Equa tion or G Equa tion is selec ted as the Premix ed M odel, you c an then cho ose t o use the zimon t or peters Flame S peed M odel (descr ibed in Turbulen t Flame S peed M odels ).You c an also modify a numb er of mo del c onstan ts, as descr ibed in Modifying the C onstan ts for the Z imon t Flame Speed M odel (p.1752 ) and Modifying the C onstan ts for the P eters F lame S peed M odel (p.1753 ). 1751Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the C-E qua tion and G-E qua tion M odelsFigur e 17.2: The S pecies M odel D ialo g Box for the G-E qua tion M odel For a non-adiaba tic pr emix ed c ombustion mo del, not e tha t the v alue y ou sp ecify f or the Turbulen t Schmidt N umb er will also b e used as the P randtl numb er for ener gy. (The Energy Prandtl N umb er will ther efore not app ear in the Visc ous M odel dialo g box for non-adiaba tic pr emix ed c ombustion models .) These par amet ers c ontrol the le vel of diffusion f or the pr ogress v ariable and f or ener gy.The progress v ariable is closely r elated t o ener gy (b ecause the flame pr ogress r esults in hea t release), so it is imp ortant tha t the tr ansp ort equa tions use the same le vel of diffusion. For additional inf ormation, see the f ollowing sec tions: 17.3.1. Modifying the C onstan ts for the Z imon t Flame S peed M odel 17.3.2. Modifying the C onstan ts for the P eters F lame S peed M odel 17.3.3. Additional Options f or the G-E qua tion M odel 17.3.4. Defining P hysical Properties f or the U nbur nt Mixture 17.3.5. Setting B oundar y Conditions f or the P rogress Variable 17.3.6. Initializing the P rogress Variable 17.3.1. Modifying the C onstan ts for the Z imon t Flame S peed M odel In gener al, you will not need t o mo dify the c onstan ts used in the equa tions pr esen ted in C-Equa tion Model Theor y in the Theor y Guide .The default v alues ar e suitable f or a wide r ange of pr emix ed flames . You c an set the Turbulen t Length Sc ale C onstan t ( in Equa tion 9.10 ),Turbulen t Flame S peed Constan t ( in Equa tion 9.8 ), the Stretch F actor C oefficien t ( in Equa tion 9.16 ), the Turbulen t Schmidt N umb er ( in Equa tion 9.1 ), and the Wall D amping C oefficien t ( in Equa tion 9.19 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1752Modeling P remix ed C ombustion17.3.2. Modifying the C onstan ts for the P eters F lame S peed M odel The P eters turbulen t flame sp eed mo del c onstan ts, as descr ibed in Peters F lame S peed M odel in the Theor y Guide , are not a vailable in the GUI b ecause the y are gener ally suitable f or a wide r ange of premix ed flames .They can, however, be acc essed fr om the TUI. The Ewald C orrector is enabled b y default and descr ibed in Peters F lame S peed M odel.The Turbulen t Schmidt N umb er ( in Equa tion 9.1 ), and the Wall D amping C oefficien t ( in Equa tion 9.19 ) are the same as those descr ibed f or the Z imon t mo del. 17.3.3. Additional Options f or the G-E qua tion M odel When the G-E qua tion mo del is enabled , the G Equa tion S ettings group b ox app ears .You c an selec t either the transp ort equa tion or algebr aic option f or the c alcula tion of the flame distanc e varianc e. Consult Peters F lame S peed M odel in the Theor y Guide for the v arianc e transp ort and algebr aic equa tion e xpressions ( Equa tion 9.5 and Equa tion 9.6 ). It is r ecommended tha t you use the transp ort equa tion option f or R ANS and the algebr aic option f or LES. When Flame C urvature Sour ce is enabled , the cur vature sour ce term in the G-E qua tion, which is the last t erm in Equa tion 9.3 , is included . By default , this t erm is e xcluded . 17.3.4. Defining P hysical P roperties f or the U nbur nt Mixture The fluid ma terial in y our domain should b e assigned the pr operties of the unbur nt mix ture, including the ther mal diffusivit y ( in Equa tion 9.8 in the Theor y Guide ). is defined as , and v alues a t standar d conditions c an b e found in c ombustion handb ooks (f or e xample ,[62] (p.4008 )). For b oth adiaba tic and non-adiaba tic c ombustion mo dels , you will need t o sp ecify the Laminar F lame Speed ( in Equa tion 9.8 in the Theor y Guide ) as a ma terial pr operty, in the Create/Edit M aterials dialo g box.You ma y cho ose t o en ter a constan t value , use a user-defined func tion, or apply the met ghalchi-k eck-la w. See Laminar F lame S peed in the Theor y Guide and Defining P hysical Properties for the U nbur nt Mixture (p.1753 ) for inf ormation ab out setting the other pr operties f or the unbur nt material. When using the Z imon t turbulen t flame sp eed mo del, if y ou w ant to include the flame str etch eff ect in your mo del, you will also need t o sp ecify a lo wer v alue than the default Critical R ate of S train ( in Equa tion 9.17 in the Theor y Guide ). As discussed in Flame S tretch E ffect in the Theor y Guide , is set t o a v ery high v alue ( ) by default , so no flame str etching o ccurs .To include flame stretching eff ects, you will need t o adjust the Critical R ate of S train based on e xperimen tal da ta for the bur ner. Because the flame str etching and flame e xtinc tion c an influenc e the turbulen t flame sp eed (as discussed in Flame S tretch E ffect in the Theor y Guide ), a realistic v alue f or the Critical R ate of Strain is requir ed f or accur ate pr edic tions .Typic al values f or lean pr emix ed c ombustion r ange from 3000 t o 8000 [147] (p.4013 ). Note tha t you c an sp ecify c onstan t values or user-defined func tions to define the Laminar F lame S peed and Critical R ate of S train. See the Fluen t Customiza tion Manual for details ab out user-defined func tions . For adiaba tic mo dels , you will also sp ecify the Adiaba tic Bur nt Temp erature ( in Equa tion 9.66 in the Theor y Guide ), which is the t emp erature of the bur nt produc ts under adiaba tic c onditions .This temp erature will b e used t o det ermine the linear v ariation of t emp erature in an adiaba tic pr emix ed combustion c alcula tion. You c an sp ecify a c onstan t value or use a user-defined func tion. 1753Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the C-E qua tion and G-E qua tion M odelsFor non-adiaba tic mo dels , you will inst ead sp ecify the Heat of C ombustion per unit mass of fuel and the Unbur nt Fuel M ass F raction ( and in Equa tion 9.68 in the Theor y Guide ). ANSY S Flu- ent will use these v alues t o comput e the hea t losses or gains due t o combustion, and include these losses/gains in the ener gy equa tion tha t it uses t o calcula te temp erature.The Heat of C ombustion can b e sp ecified only as a c onstan t value , but y ou c an sp ecify a c onstan t value or use a user-defined func tion f or the Unbur nt Fuel M ass F raction . To sp ecify the densit y for a pr emix ed c ombustion mo del, cho ose premix ed-c ombustion in the Densit y drop-do wn list and set the Adiaba tic U nbur nt Densit y and Adiaba tic U nbur nt Temp erature ( and in Equa tion 9.69 in the Theor y Guide ). For adiaba tic pr emix ed mo dels , your input f or Adiaba tic U nbur nt Temp erature ( ) will also b e used in Equa tion 9.66 in the Theor y Guide to calcula te the t emp erature. The other pr operties sp ecified f or the unbur nt mix ture ar e visc osity, specific hea t, ther mal c onduc tivit y, and an y other pr operties r elated t o other mo dels tha t are being used in c onjunc tion with the pr emix ed combustion mo del. 17.3.5. Setting B oundar y Conditions f or the P rogress Variable For pr emix ed c ombustion mo dels , you will need t o set an additional b oundar y condition a t flo w inlets and e xits: the pr ogress v ariable , .Valid inputs f or the Progress Variable are as f ollows: • : unbur nt mix ture • : bur nt mix ture 17.3.6. Initializing the P rogress Variable Often, it is sufficien t to initializ e the pr ogress v ariable to 1 (bur nt) everywher e and allo w the unbur nt ( ) mix ture en tering the domain fr om the inlets t o blo w the flame back t o the stabiliz er. A b etter initializa tion is t o pa tch an initial v alue of 0 (unbur nt) upstr eam of the flame holder and a v alue of 1 (bur nt) in the do wnstr eam r egion (af ter initializing the flo w field in the Solution Initializa tion task page). Solution → Initializa tion → Patch... See Patching Values in S elec ted C ells (p.2607 ) for details ab out pa tching v alues of solution v ariables . 17.4. Setting U p the E xtended C oher ent Flame M odel The Ex tended C oher ent Flame M odel (ECFM) solv es a tr ansp ort equa tion f or the flame sur face ar ea densit y, denot ed , in addition t o the r eaction pr ogress v ariable . Details ab out setting up the r eaction progress v ariable b oundar y and initial c onditions , and ma terial pr operties, can b e found in Setting U p the C-E qua tion and G-E qua tion M odels (p.1751 ).To use the ECFM, selec t Extended C oher ent Flame Model as the Premix ed M odel. A list of Extended C oher ent Flame M odel C onstan ts will app ear in the Species M odel dialo g box. For additional inf ormation, see the f ollowing sec tions: 17.4.1. Modifying the ECFM M odel Variant 17.4.2. Modifying the C onstan ts for the ECFM F lame S peed C losur e 17.4.3. Setting B oundar y Conditions f or the ECFM Transp ort Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1754Modeling P remix ed C ombustion17.4.4. Initializing the F lame A rea D ensit y 17.4.1. Modifying the ECFM M odel Variant The sour ce terms f or Equa tion 9.28 in the Theor y Guide are det ermined b y which ECFM mo del v ariant is used .There ar e four ECFM mo del v ariants available .The default Veynan te scheme is the r ecommended scheme , because it pr ovides the b est accur acy in most situa tions . If you w ant acc ess t o a diff erent model v ariant, you must use the f ollowing t ext command: define → models → species → set-premixed-combustion You c an then r evise the mo del c onstan ts as nec essar y. See Closur e for ECFM S ource Terms in the Theor y Guide for fur ther details . If you ar e using LES turbulenc e mo deling , see LES and ECFM as w ell. 17.4.2. Modifying the C onstan ts for the ECFM F lame S peed C losur e In the Extended C oher ent Flame M odel C onstan ts group b ox of the Species M odel dialo g box, selec t the ITNFS Treatmen t.You ha ve a choic e of constan t-delta ,mene veau ,blin t,poinsot , or constan t. The v arious ITNFS tr eatmen ts ar e descr ibed in detail in Closur e for ECFM S ource Terms in the Theor y Guide . The tr eatmen t you selec t will det ermine which c onstan ts you c an set. In all c ases , you need t o define the Turbulen t Schmidt N umb er ( ) and the Wall F lux C oefficien t. If you selec ted the constan t- delta treatmen t, you c an set the ITNFS F lame Thick ness ( in Equa tion 9.32 in the Theor y Guide ). If you selec ted the constan t treatmen t, you c an set the ITNFS Value ( in Equa tion 9.30 in the Theor y Guide ). Note tha t, in gener al, you will not need t o mo dify the c onstan ts available in the Extended Coher ent Flame M odel C onstan ts group b ox because the default v alues ar e suitable f or a wide r ange of pr emix ed flames . 1755Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the Ex tended C oher ent Flame M odelFigur e 17.3: The S pecies M odel D ialo g Box for ECFM 17.4.3. Setting B oundar y Conditions f or the ECFM Transp ort For the ECFM tr ansp ort equa tion option f or the pr emix ed c ombustion mo dels , you will need t o set an additional b oundar y condition a t flo w inlets and e xits: the flame ar ea densit y, .Valid inputs f or the Flame A rea D ensit y are as f ollows: • : no flame ar ea (unbur ned) • : bur ning with nonz ero flame ar ea 17.4.4. Initializing the F lame A rea D ensit y Often, it is sufficien t to initializ e the flame ar ea densit y to 1 (laminar flame sp eed) e verywher e and allow the unbur nt mix ture en tering the domain fr om the inlets t o de velop . Another option f or initial- ization is t o pa tch an initial v alue of 0 (not bur ning) upstr eam of the flame holder and a v alue of 10 or higher (bur ning) in the do wnstr eam r egion (af ter initializing the flo w field in the r egion). See Patching Values in S elec ted C ells (p.2607 ) for details ab out pa tching v alues of solution v ariables . 17.5. Postpr ocessing f or P remix ed C ombustion C alcula tions ANSY S Fluen t provides se veral additional r eporting options f or pr emix ed c ombustion c alcula tions .You can gener ate gr aphic al plots or alphanumer ic reports of the f ollowing it ems: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1756Modeling P remix ed C ombustion•Progress Variable •Damk ohler N umb er •Stretch F actor •Turbulen t Flame S peed •Static Temp erature •Produc t Formation R ate •Laminar F lame S peed •Critical S train R ate •Unbur nt Fuel M ass F raction •Adiaba tic F lame Temp erature These v ariables ar e contained in the Premix ed C ombustion... categor y of the v ariable selec tion dr op- down list tha t app ears in p ostpr ocessing dialo g boxes. See Field F unction D efinitions (p.2959 ) for a complet e list of flo w variables , field func tions , and their definitions .Displa ying G raphics (p.2775 ) and Reporting A lphanumer ic D ata (p.2909 ) explain ho w to gener ate gr aphics displa ys and r eports of da ta. Note tha t Static Temp erature and Adiaba tic F lame Temp erature will app ear in the Premix ed C om- bustion... categor y only f or adiaba tic pr emix ed c ombustion c alcula tions; for non-adiaba tic c alcula tions , Static Temp erature will app ear in the Temp erature... categor y.Unbur nt Fuel M ass F raction will app ear only f or non-adiaba tic mo dels . ANSY S Fluen t also pr ovides se veral additional r eporting options f or pr emix ed c ombustion c alcula tions with the ECFM mo del f or flame sp eed closur e.You c an gener ate gr aphic al plots or alphanumer ic reports of the same it ems tha t are available with the pr emix ed mo de, and in addition: •Progress Variable C urvature •Flame A rea D ensit y •Net F lame A rea P roduc tion •Flame A rea P roduc tion P1 •Flame A rea P roduc tion P2 •Flame A rea P roduc tion P3 •Flame A rea P roduc tion P4 •Intermitt ent Turb N et F lame S tretch •Flame A rea D estr uction These v ariables will also app ear in the Premix ed C ombustion... categor y. ANSY S Fluen t also pr ovides t wo additional r eporting options f or pr emix ed c ombustion c alcula tions with the G-E qua tion mo del: 1757Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Postpr ocessing f or P remix ed C ombustion C alcula tions•Mean D istanc e from F lame •Varianc e of D istanc e from F lame The Varianc e of D istanc e fr om F lame is the v arianc e of the distanc e of the instan taneous flame fr om the mean flame p osition. These v ariables app ear in the Premix ed C ombustion... categor y. For additional inf ormation, see the f ollowing sec tion: 17.5.1. Computing S pecies C oncentrations 17.5.1. Computing S pecies C onc entrations If you k now the c omp osition of the unbur nt and bur nt mix tures in y our mo del (tha t is, if y ou ha ve performed separ ate ANSY S Fluen t or e xternal analy ses of chemic al equilibr ium c alcula tions or 1D premix ed flames), you c an c omput e the sp ecies c oncentrations in the domain using cust om field func tions: •To det ermine the c oncentration of a sp ecies in the unbur nt mix ture, define the cust om func tion , wher e is the mass fr action f or the sp ecies in the unbur nt mix ture (sp ecified b y you) and is the v alue of the pr ogress v ariable (c omput ed b y ANSY S Fluen t). •To det ermine the c oncentration of a sp ecies in the bur nt mix ture, define the cust om func tion , wher e is the mass fr action f or the sp ecies in the bur nt mix ture (sp ecified b y you) and is the v alue of the progress v ariable (c omput ed b y ANSY S Fluen t). See Custom F ield F unctions (p.3038 ) for details ab out defining and using cust om field func tions . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1758Modeling P remix ed C ombustionChapt er 18: Modeling P artially P remix ed C ombustion This chapt er descr ibes ho w to use the ANSY S Fluen t's par tially-pr emix ed c ombustion mo del tha t is based on the non-pr emix ed c ombustion mo del ( Modeling N on-P remix ed C ombustion (p.1687 )) and the premix ed c ombustion mo del ( Modeling P remix ed C ombustion (p.1749 )). For inf ormation ab out the theor y behind the par tially pr emix ed c ombustion mo del, see Partially P remix ed C ombustion in the Fluent Theor y Guide . Information ab out using the par tially pr emix ed c ombustion mo del is pr esen ted in the f ollowing sec tions: 18.1. Limita tions 18.2. Using the P artially P remix ed C ombustion M odel 18.1. Limita tions •The under lying theor y, assumptions , and limita tions of the non-pr emix ed and pr emix ed mo dels apply dir ectly to the par tially pr emix ed mo del. In par ticular , the single-mix ture-fraction appr oach is limit ed t o two inlet streams , which ma y be pur e fuel, pur e oxidiz er, or a mix ture of fuel and o xidiz er.The t wo-mix ture-fraction model e xtends the numb er of inlet str eams t o thr ee, but incurs a major c omputa tional o verhead . See Limit- ations of the P remix ed C ombustion M odel (p.1749 ) for additional limita tions . •The F lamelet G ener ated M anifold (FGM) mo del is limit ed t o the c-E qua tion par tially-pr emix ed mo del. 18.2. Using the P artially P remix ed C ombustion M odel The pr ocedur e for setting up and solving a par tially pr emix ed c ombustion pr oblem c ombines par ts of the non-pr emix ed c ombustion setup and the pr emix ed c ombustion setup . An outline of the pr ocedur e is pr ovided in Setup and S olution P rocedur e (p.1759 ), along with inf ormation ab out wher e to lo ok in the non-pr emix ed and pr emix ed c ombustion chapt ers f or details . Inputs tha t are sp ecific t o the par tially premix ed c ombustion mo del ar e pr ovided in this chapt er. Information is pr ovided in the f ollowing sec tions: 18.2.1. Setup and S olution P rocedur e 18.2.2. Imp orting a F lamelet 18.2.3. Flamelet G ener ated M anifold 18.2.4. Calcula ting the L ook-U p Tables 18.2.5. Standar d Files f or Flamelet G ener ated M anifold M odeling 18.2.6. Modifying the U nbur nt Mixture Property Polynomials 18.2.7. Setting P remix F lame P ropaga tion P aramet ers 18.2.8. Modeling In C ylinder C ombustion 18.2.9. Postpr ocessing f or FGM Sc alar Transp ort Calcula tions 18.2.1. Setup and S olution P rocedur e 1.Read y our mesh file in to ANSY S Fluen t and set up an y other mo dels y ou plan t o use in c onjunc tion with the par tially pr emix ed c ombustion mo del (turbulenc e, radia tion, and so on). 1759Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.2.Enable the par tially pr emix ed c ombustion mo del. a.Turn on the Partially P remix ed C ombustion mo del in the Species M odel dialo g box. Note Make sur e a turbulenc e mo del (other than the S palar t-Allmar as mo del) is selec ted before selec ting a c ombustion mo del. Setup → Models → Species Edit... b.If you selec t the C Equa tion as the Premix ed M odel, then y ou ha ve the choic e of selec ting one of the f ollowing State Rela tion mo dels in the Chemistr y tab: Chemic al E quilibr im,Stead y Diffusion Flamelet ,Unstead y Diffusion F lamelet (for st eady-sta te simula tions star ting fr om a c onverged S teady Diffusion F lamelet solution), or Flamelet G ener ated M anif old. c.If you selec t the Extended C oher ent Flame M odel, then y ou c an selec t Chemic al E quilibr im,Stead y Diffusion F lamelet , and Unstead y Diffusion F lamelet .You c an mo dify the Extended C oher ent Flamelet M odel C onstan ts in the Premix tab . See Modifying the C onstan ts for the ECFM F lame S peed Closur e (p.1755 ) for details . Note Note tha t the Ex tended C oher ent Flame M odel (ECFM) ma y be depr ecated in futur e releases . d.If you selec t the G Equa tion as the Premix ed M odel, then y ou ha ve the choic e of selec ting one of the f ollowing State Rela tion mo dels in the Chemistr y tab: Chemic al E quilibr im or Stead y Diffusion Flamelet . 3.In the Chemistr y tab of the Species M odel dialo g box, selec t the appr opriate State Rela tion based on the t ype of par tially pr emix ed mo del y ou w ant to simula te. In ANSY S Fluen t, ther e are two types of par tially premix ed mo dels , namely a thin-flamelet mo del (equilibr ium and diffusion flamelet) and a finit e-thick ness flamelet mo del, which is a F lamelet G ener ated M anifold.You c an r efer to Non-P remix ed C ombustion in the Fluent Theor y Guide to lear n ab out diffusion flamelets or Partially P remix ed C ombustion Theor y in the Fluent Theor y Guide for FGMs . Also, you c an r efer to Overview in the Fluent Theor y Guide for gener al inf orm- ation ab out the thin-flamelet and finit e-thick ness flamelet mo dels . 4.If you selec t Flamelet G ener ated M anif old, you will also need t o define whether the FGM is c alcula ted from a pr emix ed or a diffusion flamelet , as w ell as the Turbulenc e-Chemistr y In teraction in the Premix tab.The a vailable options ( Finit e-Rate and Turbulen t Flame S peed ) are discussed in FGM Turbulen t Closur e in the Fluent Theor y Guide . 5.In the Flamelet tab , you c an mo dify the Flamelet P aramet ers as descr ibed in Flamelet G ener ated M ani- fold (p.1762 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1760Modeling P artially P remix ed C ombustion6.Gener ate a PDF lo ok-up table .The table par amet ers ar e defined in Calcula ting the L ook-U p Tables (p.1766 ). Imp ortant If ANSY S Fluen t warns y ou dur ing the par tially pr emix ed pr operties c alcula tion tha t an y paramet ers ar e out of the r ange f or the laminar flame sp eed func tion, you will need t o modify the piec ewise-linear p oints manually b efore sa ving the PDF file . See Modifying the U nbur nt Mixture Property Polynomials (p.1773 ) for details . Also, the c alcula tion of the ther mal diffusivit y uses the ther mal c onduc tivit y in the Create/Edit M aterials dialo g box. More accur ate ther mal diffusivit y polynomials c an b e obtained b y editing the ther mal c onduc tivit y in the Create/Edit M aterials dialo g box and then click ing Rec al- cula te Properties in the Properties tab . 7.Define the ph ysical pr operties f or the unbur nt ma terial in the domain. Setup → Materials ANSY S Fluen t will aut oma tically selec t the prepdf-p olynomial func tion f or Laminar F lame S peed , indic ating tha t the piec ewise-linear p olynomial func tion fr om the PDF lo ok-up table will b e used to comput e the laminar flame sp eed.You ma y also cho ose t o en ter a constan t value , use a user- defined func tion, met ghalchi-k eck-la w, or apply laminar-flame-sp eed-libr ary inst ead of a piec ewise-linear p olynomial func tion. See Laminar F lame S peed in the Fluent Theor y Guide and Defining P hysical Properties f or the U nbur nt Mixture (p.1753 ) for inf ormation ab out setting the other pr operties f or the unbur nt ma terial. 8.Set the v alues f or the mean pr ogress v ariable ( ) and the mean mix ture fraction ( ) and its v arianc e ( ) at flo w inlets and e xits. (For pr oblems tha t include a sec ondar y str eam, you will define b oundar y conditions for the mean sec ondar y par tial fr action and its v arianc e as w ell.) Setup → Boundar y Conditions See Defining N on-P remix ed B oundar y Conditions (p.1739 ) for guidelines on setting mix ture fraction and v arianc e conditions , as w ell as ther mal and v elocity conditions a t inlets . Imp ortant There ar e two ways to sp ecify a pr emix ed inlet b oundar y condition: a.If you defined the fuel c omp osition in the Boundar y tab t o be the pr emix ed inlet sp ecies , then y ou should set and in the b oundar y condition dialo g boxes. b.If you set the fuel c omp osition t o pur e fuel in the Boundar y tab , you will need t o set the correct equiv alenc e ratio ( ) and at your pr emix ed inlet b oundar y condition. For e xample , if the pr emix ed inlet of methane and air is a t an equiv alenc e ratio of 0.3, you c an a.specify the mass fr action of the fuel c omp osition of = 0.017, = 0.236, and = 0.747 in the Boundar y tab and = 1 and = 0 in the b oundar y condition dialo g box. 1761Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the P artially P remix ed C ombustion M odelb.specify the mass fr action of the fuel c omp osition of = 1.0 in the Boundar y tab and = 0.017 and = 0 in the b oundar y condition dialo g box. Metho d (a) is pr eferred sinc e it will ha ve mor e points in the flame z one than metho d (b). 9.Initializ e the v alue of the pr ogress v ariable . Solution → Initializa tion → Patch... See Initializing the P rogress Variable (p.1754 ) for details . 10.Solve the pr oblem and p erform p ostpr ocessing . See Solving the F low Problem (p.1743 ) for guidelines ab out setting solution par amet ers. (These guidelines ar e for non-pr emix ed c ombustion c alcula tions , but the y are relevant for par tially pr emix ed as w ell.) 18.2.2. Imp orting a F lamelet To imp ort an e xisting flamelet file 1.Selec t the Imp ort Flamelet option in the Chemistr y tab of the Species M odel dialo g box. 2.Click the Imp ort Flamelet F ile... butt on. In The S elec t File D ialog Box (p.569), selec t the file t o be read in to ANSY S Fluen t. After y ou ha ve complet ed this st ep, you c an sk ip ahead t o the Table tab of the Species M odel dialo g box (see Calcula ting the L ook-U p Tables (p.1766 )). 18.2.3. Flamelet G ener ated M anif old The ANSY S Fluen t Flamelet G ener ated M anifold (FGM) mo del has se veral ad vantages o ver the thin- flame equilibr ium or diffusion st eady flamelet mo dels , such as the abilit y to mo del flame quenching due t o dilution. The manif old c an b e mo deled with either a Premix ed F lamelet or a Diffusion Flamelet . When Premix ed F lamelet is selec ted as the Flamelet Type, you c an selec t to solv e the flamelets either in the Progress Variable S pac e or in the CHEMKIN P hysical S pac e (Flamelet S olution M etho d group box). For mor e inf ormation ab out these metho ds, see Premix ed FGMs in R eaction P rogress Variable Space and Premix ed FGMs in P hysical Space in the Fluent Theor y Guide . To gener ate a flamelet file , go t o the Flamelet tab of the Species M odel dialo g box (Figur e 16.16: The Species M odel D ialog Box (Flamelet Tab) (p.1717 )), wher e you will en ter v alues f or par amet ers of the flamelet. 18.2.3.1. Premix ed F lamelet G ener ated M anifolds For pr emix ed F lamelet G ener ated M anifolds , details ab out sp ecifying the Sc alar D issipa tion a t Stoi- chiometr ic M ixture Fraction c an b e found in Premix ed FGMs in R eaction P rogress Variable S pace in the Fluent Theor y Guide . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1762Modeling P artially P remix ed C ombustionFigur e 18.1: Premix ed F lamelet G ener ated M anif olds (F lamelet Tab) The Flamelet P aramet ers for pr emix ed FGMs ar e as f ollows: Numb er of G rid P oints in M ixture Fraction S pac e specifies the numb er of mix ture fraction gr id p oints distr ibut ed b etween the o xidiz er ( ) and the fuel ( ). Incr eased r esolution will pr ovide gr eater accur acy, but sinc e pr emix ed flamelets ar e solv ed a t all mixture fraction p oints, the flamelet c omputa tion time will incr ease linear ly with this input. Numb er of G rid P oints in Reac tion P rogress S pac e specifies the numb er of r eaction pr ogress gr id p oints distr ibut ed b etween unbur nt ( ) and bur nt ( ) sta tes. Incr eased r esolution will pr ovide gr eater accur acy. However, when the flamelets ar e gener- ated in the Progress Variable S pac e, the c omputa tion time and the r equir ed memor y for the flamlets calcula tion will incr ease with incr easing r esolution. Scalar D issipa tion a t Stoichiometr ic M ixture Fraction specifies the pr emix ed flamelet str ain r ate.The default of 1000/s is an appr oxima te value of the sc alar dissipa tion of a fr eely pr opaga ting (unstr ained) pr emix ed flame a t stoichiometr ic mix ture fraction (unit y equiv alenc e ratio). This option is a vailable only when the pr emix ed FGM is gener ated in the Progress Variable S pac e. User D efined F lamelet P aramet ers enables y ou t o ho ok a user-defined func tion f or sc alar dissipa tion and mean mix ture fraction (or pr ogress variable) gr id discr etiza tion Automa ted G rid Refinemen t emplo ys an adaptiv e algor ithm, which inser ts gr id p oints so tha t the change of v alues , as w ell as the change of slop es, between succ essiv e gr id p oints is less than user-sp ecified t oler ances. For inf ormation about this option, refer to Steady Diffusion F lamelet A utoma ted G rid R efinemen t in the Theor y Guide . Onc e this option is enabled , you c an sp ecify the f ollowing par amet ers: 1763Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the P artially P remix ed C ombustion M odelInitial N umb er of G rid P oints in F lamelet calcula tes a st eady solution on a c oarse gr id, with a default of . See Equa tion 8.54 in the Theor y Guide . Maximum N umb er of G rid P oints in F lamelet has a default of 64. Maximum C hange in Value R atio has a default of 0.5 and is in Equa tion 8.28 in the Theor y Guide . Maximum C hange in S lope Ratio has a default of 0.5 and is in Equa tion 8.29 in the Theor y Guide . Refine flamelet based on allows you t o selec t either the Stoichiometr ic mix ture fraction or Specified mix ture fraction . For Specified mix ture fraction , you must also sp ecify a mix ture fraction le vel at which the flamelet is solv ed dur ing the gr id refinemen t. Note When CHEMKIN P hysical S pac e is selec ted as the Flamelet S olution M etho d for the Premix ed F lamelet , the f ollowing default v alues ar e used f or the Automa ted G rid Refine- men t par amet ers: •Initial N umb er of G rid P oints in F lamelet = 12 •Maximum N umb er of G rid P oints in F lamelet =250 •Maximum C hange in Value R atio = 0.5 •Maximum C hange in S lope Ratio = 0.1 Click Calcula te Flamelets to begin the pr emix ed flamelet c alcula tion. 18.2.3.2. Diffusion F lamelet G ener ated M anifolds Gener ating diffusion F lamelet G ener ated M anifolds is similar t o gener ating S teady Diffusion F lamelets , as descr ibed in Calcula ting the F lamelets (p.1716 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1764Modeling P artially P remix ed C ombustionFigur e 18.2: Diffusion F lamelet G ener ated M anif olds (F lamelet Tab) The par amet ers f or the diffusion FGM flamelet ar e sligh tly diff erent than those f or the pr emix ed FGM flamelet (see Premix ed F lamelet G ener ated M anifolds (p.1762 ) for the definitions of the par amet ers). The additional diffusion FGM flamelet par amet ers ar e as f ollows: Initial Sc alar D issipa tion is the sc alar dissipa tion of the first flamelet in the libr ary.This c orresponds t o in Equa tion 8.53 in the Fluent Theor y Guide . Scalar D issipa tion M ultiplier specifies the r atio of the sc alar dissipa tion st ep in which succ essiv e flamelets ar e gener ated when the scalar dissipa tion is less than 1 s-1.This c orresponds t o for < 1 in Equa tion 8.53 in the Theor y Guide . Scalar D issipa tion S tep specifies the in terval between sc alar dissipa tion v alues (in s-1) for which multiple flamelets will b e calcu- lated.This c orresponds t o for ≥ 1 in Equa tion 8.53 in the Theor y Guide . Note •The FGM mo del do es not r equir e the Maximum N umb er of F lamelets par amet er. Inst ead, ANSY S Fluen t incr eases the sc alar dissipa tion un til the flamelet e xtinguishes . Hence, the Scalar D issipa tion S tep should b e set a t appr oxima tely one t wentieth of the c oun terflow diffusion flamelet e xtinc tion str ain r ate, so tha t ab out t wenty flamelets ar e calcula ted.The final, extinguishing unst eady diffusion flamelet is used t o mo del the manif old b etween the unbur nt sta te ( ) and the last st eady diffusion flamelet a t the highest sc alar dissipa tion rate just b efore extinc tion. 1765Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the P artially P remix ed C ombustion M odel•Scalar D issipa tion M ultiplier and Scalar D issipa tion S tep are used t o sp ecify the in terval of sc alar dissipa tion f or < 1 and ≥ 1, respectively. For e xample , for initial sc alar dissipa tion of 1e-3 s-1 with a Scalar D issipa tion M ultiplier of 10, and a Scalar D issipa tion S tep of 5, the flamelets will b e gener ated with sc alar dissipa tions of 1e-3, 1e-2, 0.1, 1.0, 6, 11, 16, and so on. Include E quilibr ium F lamelet determines ho w the pr ogress v ariable ( Equa tion 10.3 in the Fluent Theor y Guide ) is c alcula ted. If this option is selec ted, ANSY S Fluen t will c omput e the pr ogress v ariable using equilibr ium. Other wise , the pr ogress variable will b e comput ed using the solution of flamelet gener ated with initial sc alar dissipa tion as a denomina tor in Equa tion 10.3 in the Fluent Theor y Guide . 18.2.4. Calcula ting the L ook-U p Tables ANSY S Fluen t requir es additional inputs tha t are used in the cr eation of the lo ok-up tables . Several of these inputs c ontrol the numb er of discr ete values f or which the lo ok-up tables will b e comput ed. These par amet ers ar e input in the Table tab of the Species M odel dialo g box. For the e xample of mo deling a par tially-pr emix ed flame with either the pr emix ed or the diffusion FGM model, the Table tab of the Species M odel dialo g box is sho wn in Figur e 18.3: The S pecies M odel Dialog Box:Table Tab with no A utoma ted G rid R efinemen t (p.1766 ) when the A utoma ted G rid R efinemen t (AGR) is disabled and Figur e 18.4: The S pecies M odel D ialog Box:Table Tab D ispla ying A utoma ted G rid Refinemen t (p.1767 ) when the A GR is enabled . Figur e 18.3: The S pecies M odel D ialo g Box:Table Tab with no A utoma ted G rid Refinemen t When the aut oma ted gr id refinemen t is not selec ted, the lo ok-up table par amet ers sp ecific t o the partial-pr emix ed mo del ar e as f ollows: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1766Modeling P artially P remix ed C ombustionNumb er of M ean P rogress Variable P oints is the numb er of discr ete values of at which the lo ok-up tables will b e comput ed.This numb er is de- termined fr om the numb er of gr id p oints in the flamelet. Numb er of P rogress Variable Varianc e Points is the numb er of discr ete values of at which the lo ok-up tables will b e comput ed. Lower resolution is acceptable b ecause the v ariation along the axis is , in gener al, not as st eep as the v ariation along the axis of the lo ok-up tables . Maximum N umb er of S pecies is the maximum numb er of sp ecies tha t will b e included in the lo ok-up tables .The maximum numb er of species tha t can b e included is 200. ANSY S Fluen t will aut oma tically selec t the sp ecies with the lar gest mole fr actions t o include in the PDF table . Note tha t the PDF table v alues of densit y and sp ecific hea t are pre-calcula ted with all the sp ecies , and henc e the c onvergenc e behavior of ANSY S Fluen t will not b e af- fected b y the input f or the Maximum N umb er of S pecies . Hence, to keep table siz es small, you should set the Maximum N umb er of S pecies to only include the sp ecies tha t you ar e interested in p ostpr ocessing . Numb er of M ean E nthalp y Points is the numb er of discr ete values of en thalp y at which the lo ok-up tables will b e comput ed.This input is requir ed only if y ou ar e mo deling a non-adiaba tic sy stem. The numb er of p oints requir ed will dep end on the chemic al sy stem tha t you ar e consider ing, with mor e points requir ed in high hea t release sy stems (for e xample , hydrogen/o xygen flames). Minimum Temp erature is used t o det ermine the lo west t emp erature for which the lo ok-up tables ar e gener ated.Your input should c orrespond t o the minimum t emp erature expected in the domain (f or e xample , an inlet or w all temp erature).The minimum t emp erature should b e set 10–20 K b elow the minimum sy stem t emp erature. This option is a vailable only if y ou ar e mo deling a non-adiaba tic sy stem. Figur e 18.4: The S pecies M odel D ialo g Box:Table Tab D ispla ying A utoma ted G rid Refinemen t 1767Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the P artially P remix ed C ombustion M odelThe lo ok-up table par amet ers when Automa ted G rid Refinemen t is selec ted ar e as f ollows: Initial N umb er of G rid P oints specifies the numb er of gr id p oints for the r esolution of the mean mix ture fraction, mix ture fraction varianc e, and mean en thalp y (for non-adiaba tic sy stems); and mean pr ogress v ariable and pr ogress v ariable varianc e (for FGM). Maximum N umb er of G rid P oints specifies the maximum numb er of gr id p oints used f or tabula tion. The gr id refinemen t procedur e will stop inser ting the p oints when either the change in v alue and slop e between succ essiv e points is within toler ance or the maximum numb er of gr id p oints ar e gener ated. Maximum C hange in Value R atio specifies the maximum allo wable change in v alue of table v ariables b etween succ essiv e gr id p oints as specified b y Equa tion 8.28 in the Theor y Guide . Maximum C hange in S lope Ratio specifies the maximum change in the slop e of table v ariables b etween succ essiv e gr id p oints as sp ecified by Equa tion 8.29 in the Theor y Guide . Maximum N umb er of S pecies is the maximum numb er of sp ecies st ored in the lo okup tables . Note Automa ted G rid Refinemen t is not a vailable with t wo mix ture fractions . For the FGM mo del, you c an solv e additional tr ansp ort equa tions f or selec ted sp ecies mass fr actions , called FGM sc alars , as descr ibed in Scalar Transp ort with FGM C losur e in the Fluent Theor y Guide .To do so , click FGM Sc alar Transp ort. Figur e 18.5: The S elec t Transp orted Sc alars D ialo g Box In the Selec t Transp orted Sc alars dialo g box tha t op ens, selec t the FGM sc alars as f ollows: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1768Modeling P artially P remix ed C ombustion•To add a sp ecies t o the Transp orted Sc alars list, selec t it in the Available S pecies multiple-selec tion list and click Add. •To remo ve a sp ecies fr om the Transp orted Sc alars list back t o the Available S pecies multiple-selec tion list, selec t it and click Remo ve. For flo w b oundar ies, you c an sp ecify the b oundar y conditions f or the Scalar M ass F ractions for the selec ted tr ansp orted sc alars (in the Species tab of the c orresponding b oundar y conditions dialo g boxes). During the solution r un, ANSY S Fluen t will solv e transp ort equa tions f or the selec ted sc alars and tak e their pr e-comput ed a veraged r eaction r ates fr om the PDF lo ok-up table . Note •You must selec t the FGM tr ansp orted sc alars b efore calcula ting the PDF table . Onc e the table is calcula ted, you will no longer b e able t o mo dify the definition of the tr ansp orted FGM sc alars . In or der t o mo dify the FGM sc alar definition af ter the PDF table has b een c alcula ted, you will need t o re-imp ort or r egener ate the flamelets . •Since the sc alar equa tions do not c ouple back in to the flo w equa tions or mix ture pr operties, they could b e solv ed in a p ostpr ocessing mo de f or a st eady-sta te simula tion, such as p ollutan t formation. In such c ases , you c ould deselec t FGM Sc alar Transp ort from the Equa tions list solv ed b y ANSY S Fluen t (in the Equa tions dialo g box), and then selec t them again onc e the steady flo w field has c onverged . When y ou ar e sa tisfied with y our inputs , click Calcula te PDF Table to gener ate the lo ok-up tables . 18.2.4.1. Postpr ocessing the L ook-Up Tables with F lamelet G ener ated M anifolds For the FGM mo del, the PDF table is f our-dimensional f or adiaba tic c ases and fiv e-dimensional f or non-adiaba tic c ases . For adiaba tic PDF tables , the f our indep enden t variables ar e M ean mix ture fraction, Mean r eaction pr ogress v ariable , Mixture fraction v arianc e, and P rogress v ariable v arianc e. For non- adiaba tic tables , the additional fif th indep enden t variable is en thalp y.The FGM PDF tables c an b e post-pr ocessed using 2D cur ves and 3D sur faces b y fixing t wo or mor e indep enden t variables . The pr ocedur e to displa y the lo okup tables gr aphic ally is similar t o tha t outlined in Postpr ocessing the L ook-U p Table D ata (p.1728 ) with additional st eps as f ollows. •Adiaba tic PDF Tables 1769Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the P artially P remix ed C ombustion M odelFigur e 18.6: The PDF Table D ialo g Box (A diaba tic C ase With FGM) –3D sur faces: 1.Under Volume P aramet ers, selec t the discr ete indep enden t par amet er to be held c onstan t and fix it by sp ecifying either a slic e Inde x numb er or a Value . (For mor e inf ormation, see Postpr ocessing the L ook-U p Table D ata (p.1728 ).) 2.In a similar manner , under Surface Paramet ers, selec t and fix the sec ond discr ete indep enden t paramet er and click Plot. The r esulting plot is a 3D sur face of the selec ted Plot Variable as a func tion of the r emaining two indep enden t variables tha t ha ve not b een fix ed. –2D cur ves on 3D Sur face: 1.Under Volume P aramet ers and Surface Paramet ers, fix discr ete indep enden t par amet ers as de- scribed ab ove. 2.Under the Curve Paramet ers group b ox, selec t the X-A xis F unc tion against which the plot v ariable will b e displa yed, fix the r emaining discr ete indep enden t par amet er using c ontrols in the Constan t Value of Independent Parameter group b ox, and click Plot. The r esulting plot is a 2D cur ve of the selec ted Plot Variable as a func tion of the r emaining indep enden t variable tha t has not b een fix ed. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1770Modeling P artially P remix ed C ombustion•Non-A diaba tic PDF Tables Figur e 18.7: The PDF Table D ialo g Box (N on-A diaba tic C ase With FGM) 1.Fix the en thalp y slic e level by sp ecifying Enthalp y Slice. For non-adiaba tic PDF tables , hea t loss/gain is the fif th indep enden t variable , which is e xpressed as en thalp y levels. By default , the en thalp y level is fix ed a t the adiaba tic le vel, which is displa yed in the Enthalp y Slice, Adiaba tic = slice number lab el, as sho wn in Figur e 18.7: The PDF Table D ialog Box (N on-A diaba tic C ase With FGM) (p.1771 ). Enthalp y slic e numb ers b elow the adiaba tic slic e numb er ar e asso ciated with hea t loss , while en thalp y slic e numb ers ab ove the adiaba tic slic e numb er ar e asso ciated with en thalp y gain. 2.Depending on whether y ou w ant to displa y a 3D sur face or a 2D C urve on 3D Sur face, follow appr opriate steps f or A diaba tic PDF Tables descr ibed ab ove. 18.2.5. Standar d Files f or F lamelet G ener ated M anif old M odeling A standar d flamelet file f ormat can b e used t o read and wr ite FGM flamelets .The da ta str ucture for the standar d flamelet file f ormat is based on k eywords tha t precede each da ta sec tion. If an y of the keywords in y our flamelet da ta file do not ma tch the supp orted k eywords, you will ha ve to manually edit the file and change the k eywords t o one of the supp orted t ypes. (The ANSY S Fluen t flamelet filt er is case-insensitiv e, so y ou need not w orry ab out c apitaliza tion within the k eywords.) 1771Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the P artially P remix ed C ombustion M odelThe f ollowing k eywords ar e supp orted b y the ANSY S Fluen t filt er: •Header sec tion:HEADER •Main b ody sec tion:BODY •Numb er of sp ecies:NUMOFSPECIES •Numb er of gr id p oints:GRIDPOINTS •Pressur e:PRESSURE •Temp erature:TEMPERATURE and TEMP •Mass fr action:MASSFRACTION- •Mixture fraction:Z •Mole fr action:MOLEFRACTION- •Scalar dissipa tion f or pr emix ed flamelet: PREMIX_CHI •Reaction pr ogress:REACTION_PROGRESS •Reaction pr ogress sour ce term:PREMIX_YCDOT Note Note tha t the FGM standar d flamelet file f ormat is iden tical for b oth pr emix ed and diffusion flamelets . However, this f ormat is diff erent from the standar d format for st eady diffusion Laminar F lamelets , which is descr ibed in Calcula ting the L ook-U p Tables (p.1723 ). 18.2.5.1. Sample Standar d FGM F ile A sample FGM file in the standar d FGM f ormat is pr ovided b elow. Note tha t not all sp ecies ar e list ed in this file . HEADER PREMIX_STOICH_SCADIS 1.000000E+01 Z 0.000000E+00 NUMOFSPECIES 53 GRIDPOINTS 32 STOICH_Z 5.520020e-02 PRESSURE 1.013250E+05 BODY REACTION_PROGRESS 0.000000000E+00 5.625000000E-02 1.125000000E-01 1.687500000E-01 2.250000000E-01 2.812500000E-01 3.375000000E-01 3.937500000E-01 4.500000000E-01 5.062500000E-01 5.625000000E-01 6.187500000E-01 6.750000000E-01 7.312500000E-01 7.875000000E-01 8.437500000E-01 9.000000000E-01 9.508132748E-01 9.604275079E-01 9.668740305E-01 9.718608224E-01 9.759835686E-01 9.795270729E-01 9.826516818E-01 9.854574013E-01 9.880111737E-01 9.903602004E-01 9.925391181E-01 9.945741609E-01 9.964857158E-01 9.982899681E-01 1.000000000E+00 TEMPERATURE 3.000000000E+02 3.000000063E+02 3.000000126E+02 3.000000189E+02 3.000000251E+02 3.000000314E+02 3.000000377E+02 3.000000440E+02 3.000000503E+02 3.000000566E+02 3.000000628E+02 3.000000691E+02 3.000000754E+02 3.000000817E+02 3.000000880E+02 3.000000943E+02 3.000001006E+02 3.000001062E+02 3.000001073E+02 3.000001080E+02 3.000001086E+02 3.000001090E+02 3.000001094E+02 3.000001098E+02 3.000001101E+02 3.000001104E+02 3.000001107E+02 3.000001109E+02 3.000001111E+02 3.000001113E+02 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1772Modeling P artially P remix ed C ombustion3.000001115E+02 3.000001117E+02 massfraction-h2 0.000000000E+00 1.095241207E-53 2.190482414E-53 3.285723620E-53 4.380964827E-53 5.476206034E-53 6.571447241E-53 7.666688448E-53 8.761929655E-53 9.857170861E-53 1.095241207E-52 1.204765328E-52 1.314289448E-52 1.423813569E-52 1.533337690E-52 1.642861810E-52 1.752385931E-52 1.851324229E-52 1.870044058E-52 1.882596053E-52 1.892305813E-52 1.900333194E-52 1.907232735E-52 1.913316647E-52 1.918779651E-52 1.923752089E-52 1.928325868E-52 1.932568429E-52 1.936530852E-52 1.940252832E-52 1.943765883E-52 1.947095479E-52 . . . . . . . . . . PREMIX_YCDOT 0.000000000E+00 0.000000000E+00 0.000000000E+00 0.000000000E+00 0.000000000E+00 0.000000000E+00 0.000000000E+00 0.000000000E+00 0.000000000E+00 0.000000000E+00 0.000000000E+00 0.000000000E+00 0.000000000E+00 0.000000000E+00 0.000000000E+00 0.000000000E+00 0.000000000E+00 0.000000000E+00 0.000000000E+00 0.000000000E+00 0.000000000E+00 0.000000000E+00 0.000000000E+00 0.000000000E+00 0.000000000E+00 0.000000000E+00 0.000000000E+00 0.000000000E+00 0.000000000E+00 0.000000000E+00 0.000000000E+00 0.000000000E+00 18.2.6. Modifying the U nbur nt Mixture Property Polynomials After building the PDF table , ANSY S Fluen t aut oma tically c alcula tes the t emp erature, densit y, hea t capacit y, and ther mal diffusivit y of the unbur nt mix ture as p olynomial func tions of the mean mix ture fraction, (see Equa tion 10.23 in the Fluent Theor y Guide ).The laminar flame sp eed is aut oma tically calcula ted as a piec ewise-linear p olynomial func tion of . However, as outlined in Partially P remix ed C ombustion Theor y in the Fluent Theor y Guide , the laminar flame sp eed dep ends on details of the chemic al kinetics and molecular tr ansp ort properties, and in the pr epdf-p olynomial metho d, it is not c alcula ted dir ectly. Inst ead, cur ve fits ar e made t o flame sp eeds determined fr om detailed simula tions [43] (p.4007 ).These fits ar e limit ed t o a r ange of fuels (H2, CH4, C2H2, C2H4, C2H6, and C3H8), air as the o xidiz er, equiv alenc e ratios of the lean limit thr ough unit y, unbur nt temp eratures fr om 298 K t o 800 K, and pr essur es fr om 1 bar t o 40 bars . If your par amet ers fall outside this r ange , ANSY S Fluen t will w arn you when it c omput es the lo ok-up table . In this c ase, you will need to mo dify the piec ewise-linear p oints in the Properties tab of the Species M odel dialo g box (Fig- ure 18.8: The S pecies M odel D ialog Box (Properties Tab) (p.1774 )) before you sa ve the PDF file . If you selec ted the laminar-flame-sp eed-libr ary metho d, ANSY S Fluen t will r eport the c omput ed laminar flame sp eed. Note tha t the table v alues c annot b e mo dified . 1773Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the P artially P remix ed C ombustion M odelFigur e 18.8: The S pecies M odel D ialo g Box (P roperties Tab) For each p olynomial func tion of under Partially P remix ed M ixture Properties (Adiaba tic U nbur nt Densit y,Adiaba tic U nbur nt Temp erature,Unbur nt Cp , and Unbur nt Thermal D iffusivit y), you c an specify v alues f or Coefficien t 1,Coefficien t 2,Coefficien t 3, and Coefficien t 4 (the p olynomial c oef- ficien ts in Equa tion 10.23 in the Fluent Theor y Guide ) in the appr opriate Quadr atic of M ixture Fraction dialo g box (Figur e 18.9: The Q uadr atic of M ixture Fraction D ialog Box (p.1774 )).To op en this dialo g box, click the appr opriate Edit... butt on in the Properties tab . Figur e 18.9: The Q uadr atic of M ixture Fraction D ialo g Box If you selec ted the prepdf-p olynomial metho d, you c an also sp ecify the piec ewise-linear Mixture Fraction and its c orresponding Laminar F lame S peed for 20 diff erent points in the Piecewise Linear dialo g box (Figur e 18.10: The P iecewise Linear D ialog Box (p.1775 )).The first set of v alues is the lo wer limit and the last set of v alues is the upp er limit. Outside of either limit , the laminar flame sp eed is constan t and equal t o tha t limit. If you selec ted the laminar-flame-sp eed-libr ary metho d, you c an displa y Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1774Modeling P artially P remix ed C ombustionthe table , but y ou c annot mo dify the table v alues .To op en the Piecewise Linear dialo g box, click the Edit... butt on ne xt to Laminar F lame S peed in the Properties tab . Figur e 18.10: The P iecewise Linear D ialo g Box Imp ortant Note also tha t if y ou cho ose t o use a user-defined func tion f or the laminar flame sp eed in the Create/Edit M aterials D ialog Box (p.3386 ), the piec ewise-linear fit b ecomes ir relevant. If the sec ondar y mix ture fraction mo del is enabled , the unbur nt properties ar e a func tion of b oth the mean and sec ondar y mix ture fractions . An additional c olumn is added in the Piecewise Linear dialo g box for the sec ondar y mix ture fraction unbur nt polynomial c oefficien ts. Note tha t the Non-A diaba tic L aminar F lame S peed option when enabled includes the non-adiaba tic effects on the laminar flame sp eed b y tabula ting the laminar sp eeds in the PDF table . See Laminar Flame S peed in the Fluent Theor y Guide . 1775Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the P artially P remix ed C ombustion M odel18.2.7. Setting P remix F lame P ropaga tion P aramet ers Onc e the PDF lo ok-up table is gener ated, you c an sp ecify the turbulen t flame sp eed mo del options in the Premix ed tab of the Species M odel dialo g box. For the FGM mo del, you c an also sp ecify the varianc e settings and selec t the turbulenc e-chemistr y interaction mo del. Figur e 18.11: The S pecies M odel D ialo g Box(Premix Tab) The f ollowing c ontrols ar e available in the Turbulen t Flamelet S peed M odel group b ox. Flame sp eed M odel allows you t o selec t the metho d to calcula te turbulen t flame sp eed as descr ibed in Turbulen t Flame S peed Models in the Fluent Theor y Guide . If you selec ted zimon t, you c an adjust the Z imon t mo del par amet ers as descr ibed in Modifying the C onstan ts for the Z imon t Flame S peed M odel (p.1752 ). When the SBES turbulenc e mo del is used with the C E qua tion pr emix ed mo del, you c an also sp ecify the f ollowing additional inputs: Turbulen t Length Sc ale C onstan t (R ANS) is the mo deling c onstan t in the R ANS r egion ( in Equa tion 9.10 in the Theor y Guide ). Turbulen t Flame S peed C onstan t (R ANS) is the mo deling c onstan t in the R ANS r egion ( in Equa tion 9.8 in the Theor y Guide ). If you selec ted peters, you c an adjust the P eters mo del par amet ers as descr ibed in Modifying the Constan ts for the P eters F lame S peed M odel (p.1753 ). For the FGM mo del, you c an adjust the f ollowing additional par amet ers: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1776Modeling P artially P remix ed C ombustionTurbulenc e-Chemistr y In teraction allows you t o cho ose the metho d for mo deling the sour ce term in the pr ogress v ariable equa tion ( Equa- tion 10.9 in the Fluent Theor y Guide ).The following metho ds ar e available: •Finit e-Rate: Uses Equa tion 10.10 in the Fluent Theor y Guide to calcula te pr ogress v ariable sour ce terms from the PDF table . •Turbulen t Flame S peed : Uses Equa tion 10.11 in the Fluent Theor y Guide to calcula te pr ogress v ariable reaction sour ce terms. For mor e inf ormation ab out these mo dels , see FGM Turbulen t Closur e in the Theor y Guide . Varianc e Settings contains the Varianc e M etho d drop-do wn list tha t allo ws you t o cho ose b etween the f ollowing metho ds for calcula ting the pr ogress v ariable v arianc e: •transp ort equa tion (Equa tion 10.12 in the Fluent Theor y Guide ) •algebr aic (Equa tion 10.13 in the Fluent Theor y Guide ) •(SBES only) hybr id (Equa tion 10.14 in the Fluent Theor y Guide ) For the hybr id option, when applying Equa tion 10.14 in the Fluent Theor y Guide , the algebr aic model is used f or and the tr ansp ort equa tion mo del is used f or . For the algebr aic and hybr id options , you need t o sp ecify Algebr aic Varianc e Constan t ( in Equa tion 10.13 in the Fluent Theor y Guide ). It is r ecommended tha t you use the transp ort equa tion option f or R ANS, the algebr aic option for LES, and the hybr id option f or SBES. 18.2.8. Modeling In C ylinder C ombustion Each of the par tially pr emix ed c ombustion mo dels ma y be used f or mo deling in c ylinder c ombustion. When mo deling mor e than one c ycle of such engines , you ma y cho ose t o mo del tr app ed c ombustion produc ts and e xhaust gas r ecircula tion (EGR) using the iner t sp ecies mo del (see Setting U p the Iner t Model (p.1735 )). A Dynamic M esh E vent has also b een pr ovided f or c alcula ting the iner t comp osition, converting bur ned gases t o iner t and r esetting the c ombustion pr ocess r eady for the ne xt cycle (see Resetting Iner t EGR (p.1345 ) and Resetting Iner t EGR (p.1737 )). In the c ase of the G-E qua tion mo del, this is the only w ay to aut oma tically mo del multiple in c ylinder combustion c ycles and tak e in to acc oun t trapp ed bur ned gases r emaining in the c ylinder fr om one cycle t o the ne xt. 18.2.9. Postpr ocessing f or FGM Sc alar Transp ort Calcula tions ANSY S Fluen t provides additional r eporting options when y ou use the FGM Sc alar Transp ort option for solving tr ansp ort equa tions f or the FGM sc alars selec ted in the Selec t Transp orted Sc alars dialo g box. Quan tities f or reporting sc alar mass fr actions of the FGM sc alars ar e contained in the Premix ed Combustion… categor y the p ostpr ocessing dialo g boxes. 1777Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the P artially P remix ed C ombustion M odelRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1778Chapt er 19: Modeling a C omp osition PDF Transp ort Problem This chapt er discusses ho w to use the c omp osition PDF tr ansp ort mo del f or mo deling finit e-rate chemistr y in turbulen t flames in ANSY S Fluen t. ANSY S Fluen t has t wo diff erent discr etiza tions of the comp osition PDF tr ansp ort equa tion, namely Lagr angian and E uler ian. The Lagr angian metho d is mor e accur ate than the E uler ian metho d, but r equir es signific antly longer r un time t o converge. For inf ormation about the theor y behind the c omp osition PDF tr ansp ort mo del, see Comp osition PDF Transp ort in the Theor y Guide . Information ab out using this mo del is pr esen ted in the f ollowing sec tions: 19.1. Limita tion 19.2. Steps f or U sing the C omp osition PDF Transp ort Model 19.3. Enabling the Lagr angian C omp osition PDF Transp ort Model 19.4. Enabling the E uler ian C omp osition PDF Transp ort Model 19.5. Initializing the S olution 19.6. Monit oring the S olution 19.7. Postpr ocessing f or Lagr angian PDF Transp ort Calcula tions 19.8. Postpr ocessing f or Euler ian PDF Transp ort Calcula tions 19.1. Limita tion A limita tion tha t applies t o the c omp osition PDF tr ansp ort mo del is tha t you must use the pr essur e- based solv er as the mo del is not a vailable with the densit y-based solv er. 19.2. Steps f or U sing the C omp osition PDF Transp ort Model The pr ocedur e for setting up and solving a c omp osition PDF tr ansp ort problem is outlined b elow, and then descr ibed in detail. Rememb er tha t only st eps tha t are pertinen t to comp osition PDF tr ansp ort modeling ar e sho wn her e. For inf ormation ab out inputs r elated t o other mo dels tha t you ar e using in conjunc tion with the c omp osition PDF tr ansp ort mo del, see the appr opriate sec tions f or those mo dels . 1.Read a CHEMKIN-f ormatted gas-phase mechanism file and the asso ciated ther modynamic da ta file in the CHEMKIN M echanism dialo g box (see Imp orting a Volumetr ic Kinetic M echanism in CHEMKIN Format (p.1624 )). File → Imp ort → CHEMKIN M echanism... Imp ortant If your chemic al mechanism is not in CHEMKIN f ormat, you will ha ve to en ter the mech- anism in to ANSY S Fluen t as descr ibed in Overview of U ser Inputs f or M odeling S pecies Transp ort and R eactions (p.1614 ). 2.Enable a turbulenc e mo del. 1779Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setup → Models → Visc ous Edit... 3.Enable the Comp osition PDF Transp ort mo del and set the r elated par amet ers. Refer to Enabling the Lagr angian C omp osition PDF Transp ort Model (p.1781 ) and Enabling the E uler ian C omp osition PDF Transp ort Model (p.1783 ) for fur ther details . Setup → Models → Species Edit... 4.Check the ma terial pr operties in the Create/Edit M aterials dialo g box and the r eaction par amet ers in the Reac tions dialo g box.The default settings should b e sufficien t. Setup → Materials 5.Set the op erating c onditions , cell z one c onditions , and b oundar y conditions . Setup → Cell Z one C onditions → Operating C onditions ... Setup → Boundar y Conditions 6.Check the solv er settings . Solution → Metho ds Solution → Controls The default settings should b e sufficien t, although y ou should change the discr etiza tion t o sec ond- order onc e the solution has c onverged . 7.Initializ e the solution. You ma y need t o pa tch a high-t emp erature region t o ignit e the flame . Solution → Initializa tion → Initializ e Solution → Initializa tion → Patch... 8.Run the solution. Solution → Run C alcula tion 9.Solve the pr oblem and p erform p ostpr ocessing . Imp ortant A go od initial c ondition c an r educ e the solution time substan tially .You should star t from an existing solution c alcula ted using the Laminar F inite-Rate, EDC mo del, non-pr emix ed c om- bustion mo del, or par tially pr emix ed c ombustion mo del. See Modeling S pecies Transp ort and F inite-Rate Chemistr y (p.1613 ),Modeling N on-P remix ed C ombustion (p.1687 ), and Modeling Partially P remix ed C ombustion (p.1759 ) for fur ther inf ormation on such simula tions . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1780Modeling a C omp osition PDF Transp ort Problem19.3. Enabling the L agrangian C omp osition PDF Transp ort Model To enable the c omp osition PDF tr ansp ort mo del, selec t Comp osition PDF Transp ort in the Species Model dialo g box (Figur e 19.1: The S pecies M odel D ialog Box for Lagr angian C omp osition PDF Trans- port (p.1781 )). Setup → Models → Species Edit... When y ou enable Comp osition PDF Transp ort, the dialo g box will e xpand t o sho w the r elevant inputs . 1.Selec t Lagrangian under PDF Transp ort Options . Figur e 19.1: The S pecies M odel D ialo g Box for L agrangian C omp osition PDF Transp ort 2.Enable Volumetr ic under Reac tions . 1781Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Enabling the Lagr angian C omp osition PDF Transp ort ModelThe Comp osition Pdf Transp ort mo del uses ANSY S Fluen t stiff chemistr y solv er with ISA T enabled by default. See Using ISA T (p.1794 ) for mor e details . 3.Click the Integration P aramet ers... butt on t o op en the Integration P aramet ers D ialog Box (p.3315 ) (Fig- ure 19.2: The In tegration P aramet ers D ialog Box (p.1782 )). For additional inf ormation, see Using ISA T (p.1794 ). Figur e 19.2: The In tegration P aramet ers D ialo g Box 4.Enable Liquid M icro-M ixing to interpolate from turbulenc e mo dels and sc alar sp ectra, as not ed in Liquid Reactions in the Theor y Guide .This is applied t o cases wher e reactions in liquids o ccur a t low turbulenc e levels, among r eactants with lo w diffusivities .Therefore, a default v alue of may not b e desir able , as it over-estima tes the mixing r ate. 5.In the Mixing tab , selec t Modified C url,IEM , or EMST under Mixing M odel and sp ecify the v alue of the Mixing C onstan t ( in Equa tion 11.6 in the Theor y Guide ). For mor e inf ormation ab out par ticle diffusion, see Particle M ixing in the Theor y Guide . Imp ortant If the Liquid M icro-M ixing option is enabled , you c annot set the Mixing C onstan t. 6.You will not b e sp ecifying sp ecies b oundar y conditions in the Boundar y tab .This is only applic able t o the Euler ian PDF Transp ort Option . 7.In the Control tab , you will sp ecify the Lagr angian PDF tr ansp ort control par amet ers. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1782Modeling a C omp osition PDF Transp ort ProblemParticles P er C ell sets the numb er of PDF par ticles p er cell. Higher v alues of this par amet er will r educ e sta tistic al er ror, but incr ease c omputa tional time . Local Time S tepping is available f or st eady-sta te simula tions and c an incr ease the c onvergenc e rate by tak ing maximum allowable time-st eps on a c ell-b y-cell basis . (see Equa tion 11.4 of the Theor y Guide ). If Local Time Stepping is enabled , then y ou c an sp ecify the f ollowing par amet ers: Convection # specifies the par ticle c onvection numb er (see in Equa tion 11.4 in the Theor y Guide ). Diffusion # specifies the par ticle diffusion numb er (see in Equa tion 11.4 ). Mixing # specifies the par ticle mixing numb er (see in Equa tion 11.4 ). 19.4. Enabling the E uler ian C omp osition PDF Transp ort Model To enable the c omp osition PDF tr ansp ort mo del, selec t Comp osition PDF Transp ort in the Species Model dialo g box (Figur e 19.1: The S pecies M odel D ialog Box for Lagr angian C omp osition PDF Trans- port (p.1781 )). Setup → Models → Species Edit... When y ou enable Comp osition PDF Transp ort, the dialo g box will e xpand t o sho w the r elevant inputs . 1.Selec t Euler ian under PDF Transp ort Options . 1783Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Enabling the E uler ian C omp osition PDF Transp ort ModelFigur e 19.3: The S pecies M odel D ialo g Box for E uler ian C omp osition PDF Transp ort 2.Enable Volumetr ic under Reac tions .The Stiff C hemistr y Solver is disabled b y default and should b e enabled if the k inetic mechanism is numer ically stiff . 3.Click the Integration P aramet ers... butt on t o op en the Integration P aramet ers D ialog Box (p.3315 ) (Fig- ure 19.2: The In tegration P aramet ers D ialog Box (p.1782 )). See Using ISA T (p.1794 ) for detailed inf ormation about this dialo g box. 4.Enable Inlet D iffusion to include the diffusiv e transp ort of sp ecies thr ough the inlets of y our domain. Disable this option if the c onvective flux a t one of the inlets is v ery small, resulting in mass loss b y diffusion through tha t inlet. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1784Modeling a C omp osition PDF Transp ort Problem5.Make sur e tha t Diffusion E nergy Sour ce is enabled if y ou w ant to include sp ecies diffusion eff ects in the ener gy equa tion. 6.Enable Liquid M icro-M ixing if the fuel and o xidiz er ar e liquids with lo w diffusivities (high Schmidt numb ers). In this c ase, the Mixing C onstan t will b e calcula ted acc ording t o Equa tion 11.13 in the Theor y Guide . 7.By default , the Laminar (one mo de) ener gy equa tion is solv ed, wher e temp erature fluc tuations ar e ignor ed. By enabling Include Temp erature Fluctuations , the multi-mo de ener gy equa tion will b e solv ed as done for sp ecies . 8.In the Mixing tab , only the IEM mixing mo del is a vailable f or E uler ian PDF tr ansp ort. a.Specify the v alue of the Mixing C onstan t.The default v alue is 2 for gas phase sp ecies . Imp ortant If the Liquid M icro-M ixing option is enabled , you c annot set the Mixing C onstan t. b.Enter the numb er of Flow Iterations p er C hemistr y Update.This is the fr equenc y at which ANSY S Fluen t will up date the chemistr y dur ing the c alcula tion. Incr easing the numb er can r educ e the c ompu- tational e xpense of the chemistr y calcula tions . c.Enter the Aggr essiv eness F actor.This is a numer ical fac tor tha t controls the r obustness and the c on- vergenc e sp eed.This v alue r anges b etween 0 and 1, wher e 0 is the most r obust , but r esults in the slowest c onvergenc e.The default v alue f or the Aggr essiv eness F actor is 0.5. 9.In the Boundar y tab , define the c omp ositions of the fuel and o xidiz er.You c an selec t the b oundar y sp ecies to be displa yed as descr ibed in Overview of the P roblem S etup P rocedur e (p.1688 ). 10.(Euler ian PDF Transp ort only) Optionally , you c an selec t the monit ored sp ecies as descr ibed in Overview of the P roblem S etup P rocedur e (p.1688 ). For additional inf ormation, see the f ollowing sec tions: 19.4.1. Defining S pecies B oundar y Conditions 19.4.1. Defining S pecies B oundar y Conditions At flo w inlets , specify the Mixture Fraction in the Species tab of the b oundar y condition inlet dialo g boxes, as sho wn in Figur e 19.4: The Velocity Inlet D ialog Box for E uler ian C omp osition PDF Trans- port (p.1786 ). At outlet b oundar ies, similar ly sp ecify the Backflo w M ixture Fraction . ANSY S Fluen t alw ays applies z ero flux b oundar y conditions a t walls f or all sp ecies . 1785Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Enabling the E uler ian C omp osition PDF Transp ort ModelFigur e 19.4: The Velocity Inlet D ialo g Box for E uler ian C omp osition PDF Transp ort 19.4.1.1. Equilibr ating Inlet Str eams The Equilibr ate Inlet S tream option in the Species tab of the b oundar y conditions dialo g boxes will set the inlet c omp ositions t o their chemic al equilibr ium v alues .This option c an b e used t o mo del pilot flames and e xhaust gas r ecircula tion. Imp ortant This option should not b e enabled f or pur e fuel or o xidiz er inlets . If you ar e using the E uler ian PDF tr ansp ort mo del, specify the discr etiza tion and under-r elaxa tion f or the Euler ian PDF comp osition tr ansp ort in the Solution C ontrols and Solution M etho ds task page . 19.5. Initializing the S olution For the E uler ian PDF Transp ort mo del, the initializa tion v ariables ar e the mix ture fraction and the t em- perature.The sp ecies mass fr actions and en thalp y are calcula ted based on the fuel and o xidiz er com- position (sp ecified in the Species dialo g box) and the initializ ed mix ture fraction and t emp erature. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1786Modeling a C omp osition PDF Transp ort ProblemFigur e 19.5: The S olution Initializa tion Task P age f or E uler ian C omp osition PDF Transp ort 19.6. Monit oring the S olution At low sp eeds , combustion c ouples t o the fluid flo w thr ough densit y.The Lagr angian PDF tr ansp ort algor ithm has r andom fluc tuations in the densit y field , which in tur n causes fluc tuations in the flo w field . For st eady-sta te flo ws, statistic al fluc tuations ar e decr eased b y averaging o ver a numb er of pr evious iterations in the Run C alcula tion task page ( Figur e 19.6: The R un C alcula tion Task P age f or C omp osition PDF Transp ort (p.1788 )). 1787Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Monit oring the S olutionFigur e 19.6: The R un C alcula tion Task P age f or C omp osition PDF Transp ort Averaging r educ es sta tistic al fluc tuations and stabiliz es the solution. However, ANSY S Fluen t often in- dicates c onvergenc e of the flo w field b efore the c omp osition fields (t emp eratures and sp ecies) ar e converged .You should lo wer the default c onvergenc e cr iteria in the Residual M onit ors D ialog Box (p.3910 ), and alw ays check tha t the Total H eat Transf er R ate in the Flux R eports D ialog Box (p.3723 ) is balanc ed. It is also r ecommended tha t you monit or temp erature/sp ecies on outlet b oundar ies and ensur e tha t these ar e steady. The Lagr angian PDF metho d has the f ollowing additional solution c ontrols: Iterations in A verage and Iteration Incr emen t. By incr easing the Iterations in A verage , fluc tuations ar e smo othed out and r esid- uals le vel off a t smaller v alues . However, the c omp osition PDF metho d requir es a lar ger numb er of it er- ations t o reach st eady-sta te. It is r ecommended tha t you use the default of 50 Iterations in A verage until the st eady-sta te solution is obtained .Then, to gr adually decr ease the r esiduals , incr ease the Itera- tions in A verage by setting a Iteration Incr emen t to a v alue fr om 0 t o 1 (the v alue 0.2 is r ecommended). Subsequen t iterations will incr ease the Iterations in A verage by the Iteration Incr emen t. For additional inf ormation, see the f ollowing sec tions: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1788Modeling a C omp osition PDF Transp ort Problem19.6.1. Running U nsteady Comp osition PDF Transp ort Simula tions 19.6.2. Running C ompr essible Lagr angian PDF Transp ort Simula tions 19.6.3. Running Lagr angian PDF Transp ort Simula tions with C onjuga te Heat Transf er 19.6.1. Running U nstead y Comp osition PDF Transp ort Simula tions For unst eady Lagr angian c omp osition PDF tr ansp ort simula tions , a fr actional st ep scheme is emplo yed wher e the PDF par ticles ar e ad vanced o ver the time st ep, and then the flo w is ad vanced o ver the time step. Unlike steady-sta te simula tions , comp osition sta tistics ar e not a veraged o ver it erations , and t o reduc e sta tistic al er ror y ou should incr ease the numb er of par ticles p er cell in the Solution M onit ors dialo g box. For lo w sp eed flo ws, the ther mo-chemistr y couples t o the flo w thr ough densit y. Statistic al er rors in the c alcula tion of densit y ma y cause c onvergenc e difficulties b etween time st ep it erations . If you e x- perienc e this , incr ease the numb er of PDF par ticles p er cell, or decr ease the densit y under-r elaxa tion. 19.6.2. Running C ompr essible L agrangian PDF Transp ort Simula tions Compr essibilit y is included when ideal-gas is selec ted as the densit y metho d in the Create/Edit M ater- ials D ialog Box (p.3386 ). For such flo ws, par ticle in ternal ener gy is incr eased b y over the time st ep , wher e is the c ell pr essur e and is the change in the par ticle sp ecific v olume o ver the time step. 19.6.3. Running L agrangian PDF Transp ort Simula tions with C onjuga te Heat Transf er When solid z ones ar e pr esen t in the simula tion, ANSY S Fluen t solv es the ener gy equa tion in the turbu- lent flo w zones b y the Lagr angian M onte Carlo par ticle metho d, and the ener gy equa tion in the solid zones b y the finit e-volume metho d. 19.7. Postpr ocessing f or L agrangian PDF Transp ort Calcula tions For additional inf ormation, see the f ollowing sec tions: 19.7.1. Reporting Options 19.7.2. Particle Tracking Options 19.7.1. Rep orting Options ANSY S Fluen t provides se veral reporting options f or the Lagr angian c omp osition PDF tr ansp ort calcu- lations .You c an gener ate gr aphic al plots or alphanumer ic reports of the f ollowing it ems: •Static Temp erature •Mean S tatic Temp erature •RMSE S tatic Temp erature •Mass fr action of sp ecies-n •Mean sp ecies-n M ass F raction 1789Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Postpr ocessing f or Lagr angian PDF Transp ort Calcula tions•RMS sp ecies-n M ass F raction The instan taneous c omp osition ( Static Temp erature and Mass fr action of sp ecies-n ) in a c ell ar e calcula ted as , (19.1) wher e = instan taneous c ell sp ecies mass fr action or t emp erature at the pr esen t iteration = numb er of par ticles in the c ell = par ticle mass fr action or t emp erature = par ticle mass Mean and r oot-mean-squar e-er ror (RMSE) t emp eratures ar e calcula ted in ANSY S Fluen t by averaging instan taneous t emp eratures o ver a user-sp ecified numb er of pr evious it erations (see Monit oring the Solution (p.1787 )). Note tha t for st eady-sta te simula tions , instan taneous t emp eratures and sp ecies r epresen t a M onte Carlo realiza tion and ar e as such unph ysical. Mean and RMSE quan tities ar e much mor e useful. 19.7.2. Particle Track ing Options When y ou ha ve enabled the Lagr angian c omp osition PDF tr ansp ort mo del, you c an displa y the tr ajec t- ories of the PDF par ticles using the Particle Tracks D ialog Box (p.3881 ) (Figur e 19.7: The P article Tracks Dialog Box for Tracking PDF P articles (p.1791 )). Results → Graphics → Particle Tracks New... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1790Modeling a C omp osition PDF Transp ort ProblemFigur e 19.7: The P article Tracks D ialo g Box for Track ing PDF P articles Selec t the Track PDF Transp ort Particles option t o enable PDF par ticle tr acking.To sp eed up the plotting pr ocess, you c an sp ecify a v alue for Skip, which will plot only e very th par ticle . For details about setting other par amet ers in the Particle Tracks dialo g box, see Displa ying of Trajec tories (p.2028 ). When y ou ha ve finished setting par amet ers, click Displa y to displa y the par ticle tr ajec tories in the graphics windo w. 19.8. Postpr ocessing f or E uler ian PDF Transp ort Calcula tions For additional inf ormation, see the f ollowing sec tions: 19.8.1. Reporting Options 19.8.1. Rep orting Options To postpr ocess the E uler ian c omp osition PDF tr ansp ort mo del, the f ollowing v ariables ar e available for each mo de: •Mixture fraction 1791Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Postpr ocessing f or Euler ian PDF Transp ort Calcula tions•Mass fr action of sp ecies in mo de n •Temp erature of mo de n •Sensible E nthalp y of mo de n Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1792Modeling a C omp osition PDF Transp ort ProblemChapt er 20: Using C hemistr y Acceler ation ANSY S Fluen t can mo del detailed chemic al kinetics in laminar and turbulen t flames . Laminar flames ar e modeled with the Finit e-Rate/N o TCI option, while f our turbulenc e-chemistr y interaction mo dels ar e available f or turbulen t flames ( Finit e-Rate/N o TCI,Eddy-D issipa tion C onc ept,Lagrangian PDF Transp ort, and Euler ian PDF Transp ort). Detailed chemic al mechanisms ar e invariably numer ically stiff and c omput e-in tensiv e. ANSY S Fluen t provides f ollowing metho ds t o acc elerate these c omputa tions: •ISAT •Dynamic M echanism R educ tion (DMR) •Chemistr y Agglomer ation •Dimension R educ tion •Dynamic C ell C lustering (DC C) (a vailable with the ANSY S CHEMKIN-CFD solv er only) •Dynamic A daptiv e Chemistr y (DA C) (a vailable with the ANSY S CHEMKIN-CFD solv er only) All of the metho ds ar e enabled or disabled in the Integration P aramet ers dialo g box, acc essed fr om the Species M odel dialo g box by click ing the Integration P aramet ers... butt on in the Reac tions group box: Setup → Models → Species Edit... Figur e 20.1: The In tegration P aramet ers D ialo g Box 1793Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.All of the acc eleration metho ds induc e some accur acy loss , and the c ontrolling par amet ers should b e carefully adjust ed t o ensur e tha t this inaccur acy is acc eptable , see Chemistr y Acceleration in the Fluent Theor y Guide . In most c ases , applying ISA T and D ynamic M echanism R educ tion (DMR) t ogether should give the b est p erformanc e. Further inf ormation ab out using the chemistr y acc eleration mo dels is presen ted in the f ollowing sec tions: 20.1. Using ISA T 20.2. Using D ynamic M echanism R educ tion 20.3. Using C hemistr y Agglomer ation 20.4. Dimension R educ tion 20.5. Using D ynamic C ell C lustering 20.6. Using D ynamic A daptiv e Chemistr y with ANSY S Fluen t CHEMKIN-CFD S olver 20.1. Using ISA T In-S itu A daptiv e Tabula tion (ISA T) is a st orage-r etrieval metho d tha t constr ucts a chemistr y table a t run time (in-situ) with a user-sp ecified in terpolation accur acy (adaptiv e tabula tion). ISAT can b e used with all C hemistr y solv ers e xcept the None - E xplicit S our ce solv er option. ISAT is not a vailable f or simula tions with sur face reactions . For ODE solv ers (S tiff C hemistr y and CHEMKIN-CFD), ANSY S Fluen t uses t wo er ror toler ances (under ODE P aramet ers): •Absolut e Error Toler anc e: by default , set t o 10-8. •Rela tive Error Toler anc e: by default , set t o 10-9 for the S tiff C hemistr y solv er and 10-4 for the CHEMKIN-CFD solv er. The default v alues should b e sufficien t for most applic ations , although these t oler ances ma y need t o be decr eased f or some c ases such as ignition. For pr oblems in which the accur acy of the chemistr y in- tegrations is cr ucial, it ma y be useful t o test the accur acy of the er ror toler ances in simple z ero-dimen- sional and one-dimensional t est simula tions with par amet ers c ompar able t o those in the full simula tion. If you w ant to use chemistr y agglomer ation t ogether with ISA T, enable Chemistr y Agglomer ation in the Integration P aramet ers dialo g box and sp ecify the chemistr y agglomer ation Error Toler anc e ( ). More inf ormation c an b e found in Using C hemistr y Agglomer ation (p.1802 ). For additional inf ormation, see the f ollowing sec tions: 20.1.1. ISAT Paramet ers 20.1.2. Monit oring ISA T 20.1.3. Using ISA T Efficien tly 20.1.4. Reading and Writing ISA T Tables 20.1.1. ISA T Paramet ers If you ha ve selec ted ISAT under Integration M etho d, you will then b e able t o set additional ISA T paramet ers.The numer ical er ror in the ISA T table is c ontrolled b y the ISAT Error Toler anc e under ISAT Paramet ers.The default ISAT Error Toler anc e of 0.001 ma y be sufficien tly accur ate for temp er- ature and major sp ecies , but will most lik ely need t o be decr eased t o get accur ate minor sp ecies and pollutan t predic tions . For st eady-sta te simula tions , it ma y help t o star t with a high er ror toler ance Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1794Using C hemistr y Accelerationduring the initial it erations t owards a c onverged solution. A lar ger er ror toler ance results in smaller tables and quick er run times , but gr eater er ror. Imp ortant After y our st eady simula tion is c onverged , you should alw ays decr ease the ISAT Error Tol- eranc e and p erform fur ther it erations un til the sp ecies tha t you ar e in terested in ar e un- changed . The Max. Storage is the maximum R AM used b y the ISA T table , and has a default v alue of 100 MB . Gener ally, you do not need t o set it t o a v alue lar ger than 500 MB .The v alue of Verb osit y allo ws you to monit or ISA T performanc e in diff erent levels of detail. See Monit oring ISA T (p.1795 ) for details ab out this par amet er. To pur ge the ISA T table , click the Clear ISA T Table butt on. See Using ISA T Efficien tly (p.1796 ) for mor e details . 20.1.2. Monit oring ISA T You c an monit or ISA T performanc e by setting the Verb osit y in the Integration P aramet ers dialo g box. For a Verb osit y of 1 or 2, ANSY S Fluen t wr ites the f ollowing inf ormation p eriodically t o a file named case_file_name _stats.out : •total numb er of quer ies •total numb er of quer ies r esulting in retrieves •total numb er of quer ies r esulting in grows •total numb er of quer ies r esulting in adds •total numb er of quer ies r esulting in direct int egrations •cumula tive CPU sec onds in ISA T •cumula tive CPU sec onds outside ISA T •cumula tive wall-clo ck time in sec onds (tha t is, total CPU time in ISA T plus t otal CPU time out of ISA T plus CPU idle time) The ISA T Verb osit y option of 2 is f or e xpert users who ar e familiar with ISA T v5.0 [96] (p.4010 ). ANSY S Fluen t wr ites out the f ollowing files f or Verb osit y = 2: •table_name _stats.out , as descr ibed ab ove •table_name _ODE_accuracy.out reports the accur acy of the ODE in tegrations . For e very new ISA T table entry, if the maximum absolut e error in t emp erature or sp ecies is gr eater than an y pr evious er ror, a line is written t o this file .This line c onsists of the t otal numb er of ODE in tegrations p erformed up t o this time , the maximum absolut e sp ecies er ror, the absolut e temp erature error, the initial t emp erature and the time step. •table_name _ODE_diagnostic.out prints diagnostics fr om the ODE solv er •table_name _ODE_warning.out prints w arnings fr om the ODE solv er 1795Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using ISA TInitially , the table name is equal b y default t o the cur rent case name , and is changed as the table is written or r ead. Each pr ocessor builds its o wn ISA T table . If Verb osit y is enabled , each c omput e no de wr ites out the Verb osit y file(s) with the no de ID numb er app ended t o the file name . 20.1.3. Using ISA T Efficien tly Efficien t use of ISA T requir es though tful c ontrol.What follows are some detailed r ecommenda tions concerning the achie vemen t of this goal. Imp ortant •The numer ical er ror in the ISA T table is c ontrolled b y the ISAT Error Toler anc e, which has a default v alue of 0.001. This v alue is r elatively lar ge, which allo ws fast er convergenc e times f or steady-sta te simula tions . However, onc e the solution has c onverged , it is imp ortant to reduc e this ISAT Error Toler anc e and r e-converge.This pr ocess should b e repeated un til the sp ecies that you ar e interested in mo deling ar e unchanged . Unsteady simula tions should b e run with a sufficien tly small ISAT Error Toler anc e so tha t the sp ecies of in terest ar e unaff ected b y this paramet er. Note tha t as the er ror toler ance is decr eased , the memor y and time r equir emen ts to build the ISA T table will incr ease substan tially .There is a lar ge p erformanc e penalt y in sp e- cifying an er ror toler ance smaller than is needed t o achie ve acc eptable accur acy, and the er ror toler ance should b e decr eased gr adually and judiciously . •As descr ibed in Mesh P artitioning and L oad B alancing (p.3067 ), you c an selec t portions of the simula tion t o consider when p erforming d ynamic load balancing in multipr ocessor simula tions . If the ISAT option is selec ted in the Weigh ting tab of the Partitioning and L oad B alancing D ialog Box (p.3887 ), the time r equir ed f or solving chemistr y will b e fac tored in when assigning the computa tional c ells t o each a vailable pr ocessor . It is r ecommended tha t you selec t this option when solving stiff chemistr y, par ticular ly when the D ynamic M echanism R educ tion metho d is enabled; thus , mor e resour ces c an b e allo cated f or the c ells with the lar ger mechanisms . During the initial it erations , before a st eady-sta te solution is a ttained , transien t comp osition sta tes occur tha t are not pr esen t in the st eady-sta te solution. For e xample , you migh t pa tch a high t emp er- ature region in a c old fuel-air mixing z one t o ignit e the flame , wher eas the c onverged solution ne ver has hot r eactants without pr oduc ts. Since all sta tes tha t are realiz ed in the simula tion ar e tabula ted in ISA T, these initial mappings ar e wasteful of memor y, and c an degr ade ISA T performanc e. If the table fills the allo cated memor y and c ontains en tries fr om an initial tr ansien t tha t are no longer acc essed , it ma y be beneficial t o pur ge the ISA T table .This is achie ved b y either clear ing it in the Integration Paramet ers dialo g box, or sa ving y our c ase and da ta files , exiting ANSY S Fluen t, then r estar ting ANSY S Fluen t and r eading in the c ase and da ta.This c an also b e done with the TUI c ommand define/models/species/clear-isat-table . From e xperienc e, ISAT performs v ery well on pr emix ed turbulen t flames , wher e the r ange of c omp os- ition sta tes ar e smaller than in non-pr emix ed flames . ISAT performanc e degr ades in flames with lar ge residenc e times , wher e mor e work is r equir ed in the ODE in tegrator. 20.1.4. Reading and Writing ISA T Tables ANSY S Fluen t can wr ite and subsequen tly r ead ISA T tables . However, it is in gener al not r ecommended to wr ite and r ead ISA T tables f or the f ollowing r eason: ISAT tabula tes chemic al sta tes tha t are sp ecific Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1796Using C hemistr y Accelerationto a single simula tion. The ISA T tabula ted c omp osition sta tes ar e det ermined b y the geometr y, boundar y conditions , physics mo dels such as turbulenc e and r adia tion, ther modynamic and tr ansp ort properties, as w ell the chemic al mechanism. If an y of these par amet ers change , the r ealiz ed c omp osition spac e changes , and signific ant par ts of the e xisting ISA T table ar e no longer acc essed .These un-acc essed ISAT table en tries slo w in terpolation and decr ease the numb er of useful acc essed table en tries tha t can b e added . Since the time c onsumed building the ISA T table is t ypic ally much smaller than simula tion run times , it is ad vised t o rebuild the table when r estar ting . When ANSY S Fluen t is r un in par allel, each par tition builds its o wn ISA T table and do es not e xchange information with ISA T tables on other c omput e no des.You c an sa ve the ISA T tables on all c omput e nodes: File → Write → ISAT Table ... Each c omput e no de wr ites out its ISA T table t o the sp ecified file name , with the no de ID numb er ap- pended t o the file name . For e xample , a sp ecified file name of my_name on a t wo comput e no de r un will wr ite two files c alled my_name-0.isat and my_name-1.isat . Subsequen t runs c an star t from e xisting ISA T tables b y reading them in to memor y. File → Read → ISAT Table ... Files c an b e read in t wo ways: •Parallel no des c an r ead in c orresponding ISA T tables sa ved fr om a pr evious par allel simula tion. The app ended node ID should not b e remo ved fr om the input file name . Note The abilit y to use ISA T tables gener ated fr om a par allel simula tion with a diff erent numb er of par allel no des is not supp orted. •All no des c an r ead one unique ISA T table .You migh t use this appr oach if y ou ha ve a lar ge table fr om a serial simula tion. ANSY S Fluen t first checks t o see if the e xact file name tha t you sp ecified e xists , and if it does, all no des will r ead this one file . 20.2. Using D ynamic M echanism Reduc tion Computa tional time incr eases with the siz e of the chemic al kinetics mechanism used in the simula tion. Dynamic M echanism R educ tion (DMR) decr eases the mechanism siz e at each c ell (or par ticle) t o include only those sp ecies and r eactions nec essar y for accur ate mo deling (within defined t oler ances) of the chemic al kinetics a t the lo cal conditions .This is p erformed a t every flo w it eration (f or st eady simula tions) or time st ep (f or tr ansien t simula tions). Because the mechanism is only r equir ed t o be accur ate at the local conditions , smaller r educ ed mechanisms c an b e used with less accur acy loss than when using skeletal mechanism r educ tion, wher e a single r educ ed mechanism is used thr oughout the simula tion. The sp eed-up fr om this appr oach is pr oblem-dep enden t, but on a verage is ab out a fac tor of t wo or mor e compar ed t o a c ase with no chemistr y acc eleration. For an e ven gr eater incr ease in p erformanc e, you c an use D ynamic M echanism R educ tion with an y combina tion of the other chemistr y acc eleration options a vailable in ANSY S Fluen t. In most c ases , ap- plying ISA T and DMR t ogether should giv e the b est p erformanc e. Note, however, tha t ISA T performanc e 1797Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M echanism R educ tiondegr ades when accur acy requir emen ts ar e very str ict or when c onditions ar e not r evisit ed of ten in a simula tion. An example is unst eady ignition simula tions , wher e ISA T table en tries ma y not b e re-used . However, the imp ortant sp ecies and r eactions c an v ary widely dur ing the simula tion; for e xample , man y of the lo w temp erature ignition r eactions ar e only r equir ed f or the small spar k zone and shor t spar k duration. In such situa tions , you ma y achie ve better p erformanc e using D ynamic M echanism R educ tion along with dir ect integration metho d rather than ISA T. Combining multiple chemistr y acc eleration metho ds, however, comp ounds accur acy loss , sinc e each of these metho ds acc elerates the simula tion b y sacr ificing some accur acy. In gener al, greater sp eed-up is achie vable when the full mechanism is lar ger, because ther e is p otential f or a gr eater degr ee of r e- duc tion. Imp ortant When using D ynamic M echanism R educ tion along with ISA T, setting the er ror toler ance for either appr oach ab ove its default v alue degr ades accur acy fast er than when either metho d is used alone . Dynamic M echanism R educ tion is p erformed using the D irected R elation G raph (DR G) algor ithm. For details of the DMR algor ithm, refer to the discussion in Dynamic M echanism R educ tion in the Fluent Theor y Guide . You c an enable D ynamic M echanism R educ tion thr ough either the gr aphic al user in terface (GUI) or the text user in terface (TUI) as f ollows. •In the GUI, enable the Dynamic M echanism Reduc tion option in the Integration P aramet ers dialo g box. •In the TUI, enter the f ollowing t ext command in the c onsole: define/models/species/integration-parameters When pr ompt ed with Enable Dynamic Mechanism Reduction? , answ er with yes . Note tha t it is not nec essar y to enable C hemistr y Acceleration Exp ert mo de in or der t o use D ynamic Mechanism R educ tion. For additional inf ormation, see the f ollowing sec tions: 20.2.1. Mechanism R educ tion P aramet ers 20.2.2. Monit oring and P ostpr ocessing D ynamic M echanism R educ tion 20.2.3. Using D ynamic M echanism R educ tion E ffectively 20.2.1. Mechanism Reduc tion P aramet ers In ANSY S Fluen t, Dynamic M echanism R educ tion is c ontrolled b y the er ror toler ance and the tar get species list , as descr ibed b elow. Error Toler anc e ( in Equa tion 12.4 in the Fluent Theor y Guide ).The default v alue f or er ror toler ance is 0.01 , which should work well for most simula tions , balancing sp eed and accur acy. However, a lar ger t oler ance ma y be sufficien t for some simula tions (f or e xample , steady-sta te simula tions with mo derate accur acy requir emen ts), while a smaller t oler ance ma y be requir ed in other c ases with str icter accur acy requir emen ts (for e xample , modeling aut o-ignition dela y times f or a highly c omple x fuel). In gener al, a lar ger t oler ance yields fast er, but less accur ate simula tions . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1798Using C hemistr y AccelerationThe er ror toler ance can b e adjust ed thr ough the GUI or TUI as f ollows: •In the GUI, set Error Toler anc e to the desir ed v alue in the Mechanism Reduc tion P aramet ers group box in the Integration P aramet ers dialo g box. •In the TUI, enter the f ollowing t ext command:define/models/species/integration-para- meters .When pr ompt ed with Mechanism Reduction Error Tolerance , enter the desir ed toler ance (a p ositiv e, nonz ero value) or pr ess Enter to retain the default v alue . Note •In the TUI, you c an also enable C hemistr y Acceleration Exp ert mo de, other chemistr y acc el- eration metho ds, and sp ecify ODE in tegrator par amet ers (see Using ISA T (p.1794 ) for details about these par amet ers). •Chemistr y Acceleration Exp ert mo de should only b e enabled if y ou w ant to mo dify the default target sp ecies list. Target S pecies List As descr ibed in the Dynamic M echanism R educ tion in the Fluent Theor y Guide , the tar get sp ecies ar e those species tha t you w ant to pr edic t most accur ately.The default numb er of tar get sp ecies is 3. The first default tar get sp ecies is h ydrogen r adic al. DRG will add t wo other sp ecies with the lar gest mass fractions t o complet e the tar get sp ecies list a t each flo w time st ep or it eration. DRG will then iden tify all other sp ecies tha t must also b e included in the mechanism in or der t o accur ately mo del these tar gets . Although y ou should r arely need t o alt er the default tar get sp ecies list , ANSY S Fluen t provides an option t o sp ecify tar get sp ecies of y our choic e.The designa ted tar get sp ecies c an b e sp ecified only in the TUI when C hemistr y Acceleration Exp ert mo de is enabled . Enter the t ext command define/models/species/integration-parameters and then answ er yes when prompt ed with Enable Chemistry Acceleration expert? . ANSY S Fluen t provides the abilit y to explicitly sp ecify tar get sp ecies . From y our mix ture ma terial list , you c an selec t an y numb er of tar get sp ecies t o be included in the k inetics mechanism. In c ase no tar gets w ere selec ted ( ) or the numb er of user-selec ted tar gets is less than the minimum numb er of tar get sp ecies ( ), the DR G algor ithm will add the ( ) species with the lar gest mass fr actions t o the tar get sp ecies list. As discussed in the Dynamic M echanism R educ tion in the Fluent Theor y Guide , ther e is an option t o remo ve a sp ecies fr om the tar get list whene ver its mass fr action is b elow a sp ecified thr eshold .This option is disabled b y default in ANSY S Fluen t (tha t is, the default v alue f or minimum mass fr action is 0). When sp ecifying Target S pecies List , you will r eceive the f ollowing pr ompts in the c onsole: 1.Minimum number of target species [3] Enter the desir ed numb er of tar gets . 2.Minimum mass fraction of target species [0] Enter minimum allo wable tar get mass fr action. 1799Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M echanism R educ tionThe cur rent tar get sp ecies list will b e displa yed in the c onsole windo w (f or e xample , the c onsole output f or the default tar get sp ecies c onsisting of h ydrogen r adic al will b e Current target species list = (h) ). 3.Enter target species list... Species name [""] Enter tar get sp ecies name , for e xample ,"ch4" . Imp ortant You must enter the c omplet e name of the sp ecies as it app ears in the Chemic al F ormula field in the Create/Edit M aterials dialo g box within quot es (" "). After y ou en ter the first tar get sp ecies , you will b e pr ompt ed t o sp ecify the sec ond one , and so on, until you pr ess Enter to complet e the setup . Note, tha t if y ou ha ve en tered 0 for the minimum numb er of tar get sp ecies and ha ve not provided an y tar get sp ecies (tha t is, the numb er of user-selec ted tar gets , , is z ero), ANSY S Fluen t will aut oma tically selec t the thr ee sp ecies with the lar gest mass fr action and use them as the tar get sp ecies in the DR G algor ithm. 20.2.2. Monit oring and P ostpr ocessing D ynamic M echanism Reduc tion When C hemistr y Acceleration e xpert is enabled in the TUI, two additional field v ariables ar e available to be monit ored or e xamined in p ostpr ocessing: •DRG Reduc ed N umb er of S pecies in the Species… categor y •DRG Reduc ed N umb er of Reac tions in the Reac tions ... categor y These field v ariables quan tify the siz e of the r educ ed mechanism a t each c ell or par ticle in the domain (the numb er of r etained sp ecies and r eactions , respectively). When y ou use DMR in c ombina tion with ISA T, ANSY S Fluen t will r eport values of z ero for DRG Reduc ed Numb er of S pecies and DRG Reduc ed N umb er of Reac tions for those c ells wher e the ANSY S solv er comput ed the solution using table lo okup inst ead of dir ect integration in the ISA T algor ithm. A c ell value of z ero DRG Reduc ed N umb er of S pecies does not imply tha t the DMR algor ithm elimina ted all sp ecies fr om the mechanism; rather , it indic ates tha t the ANSY S solv er p erformed ISA T table lo okup to obtain the chemistr y solution a t the c ell. If you w ant to view the c ells f or which ISA T table lo okup w as p erformed in the last it eration or time step, displa y the DRG Reduc ed N umb er of S pecies plot clipp ed t o a r ange of 0 t o 0. (Make sur e tha t the Node Value option is deselec ted in the p ostpr ocessing dialo g boxes.) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1800Using C hemistr y AccelerationIf you w ant to view the c ells f or which DMR w as p erformed in the last it eration or time st ep, displa y the DRG Reduc ed N umb er of S pecies plot clipp ed t o a r ange of 1 t o a global maximum v alue (as it app ears in the Max field when Global R ange is selec ted in the p ostpr ocessing dialo g boxes). Note The DMR p ostpr ocessing field v ariables ar e not st ored in the da ta file and , henc e, will not be available f or p ostpr ocessing in the ne xt session. If you w ant to postpr ocess these v ariables in your ne xt session, read the da ta file and p erform a single it eration or time st ep (f or st eady- state or tr ansien t simula tions , respectively) in or der f or the DMR da ta to be calcula ted and available f or viewing . 20.2.3. Using D ynamic M echanism Reduc tion E ffectively As descr ibed in Dynamic M echanism R educ tion in the Fluent Theor y Guide , mechanism r educ tion is performed a t each c ell or par ticle , onc e per time st ep (f or tr ansien t simula tions) or p er flo w it eration (for st eady-sta te simula tions). It is assumed tha t the r educ ed mechanism cr eated f or the star ting c on- ditions will r emain v alid f or the en tire transp ort time st ep o ver which the chemistr y ODE is in tegrated. If the chemistr y integration time in terval is v ery lar ge, the chemic al sta te can change signific antly, degr ading the accur acy of the r educ ed mechanism. In some c ases (par ticular ly tr ansien t simula tions such as ignition) it ma y be nec essar y to enf orce smaller flo w time st eps in or der t o eff ectively use Dynamic M echanism R educ tion. In this w ay the r educ ed mechanisms ar e up dated mor e frequen tly t o match the changing chemic al sta tes. Note tha t Dynamic M echanism R educ tion w orks b est when ther e ar e signific ant regions in a c omputa- tional domain and/or times dur ing a simula tion with r elatively lo w chemic al ac tivit y (for e xample , low temp erature, low mixing of fuel/o xidiz er, low concentrations of r eactive sp ecies , and so on). Consider a simple opp osed flo w diffusion flame pr oblem with pur e fuel as one str eam and pur e oxygen as the other str eam. Large mechanisms (which, dep ending on the er ror toler ance, ma y be close t o the full mechanism siz e) will lik ely b e used in the mixing r egion wher e the flame is lo cated, while smaller mechanisms w ould b e used elsewher e in the domain. You should not e xpect much sp eed-up if a v ery large fr action of y our gr id cells (f or e xample , 90%) ar e in the flame r egion. In st eady-sta te simula tions , you c an impr ove the solution time b y first r unning t o convergenc e with a lar ger er ror toler ance , and then r estar ting the simula tion r epeatedly , gradually decr easing the er ror toler ance until you r each the desir ed accur acy level. For e xample , if y ou first c onverge the solution with the er ror toler ance , then it erate the solution fur ther t o convergenc e with the lo wer er ror toler ance, , and then with the desir ed er ror toler ance , you will gener ally b e able t o achie ve fast er convergenc e than it erating fr om initial c onditions with the er ror toler ance . Imp ortant As descr ibed in Mesh P artitioning and L oad B alancing (p.3067 ), you c an selec t portions of the simula tion t o consider when p erforming d ynamic load balancing in multipr ocessor simula tions .When using the D ynamic M echanism R educ tion along with ISA T, it is r ecom- mended tha t you selec t the ISAT option in the Weigh ting tab of the Partitioning and L oad Balancing D ialog Box (p.3887 ) when solving stiff chemistr y. If ISAT is selec ted, the time r e- quir ed f or solving chemistr y will b e fac tored in when assigning the c omputa tional c ells t o each a vailable pr ocessor ; thus , mor e resour ces c an b e allo cated f or the c ells with the lar ger mechanisms . 1801Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic M echanism R educ tion20.3. Using C hemistr y Agglomer ation The C hemistr y Agglomer ation metho d reduc es the numb er of c alls t o the c omputa tionally e xpensiv e ODE in tegrator b y clust ering c ells with similar c omp ositions .The siz e of these clust ers is det ermined by the agglomer ation par amet ers Error Toler anc e ( ) and Temp erature Bin ( ) in the Integration Paramet ers dialo g box. Larger v alues of and result in a lar ger numb er of agglomer ated c ells, fewer calls t o the r eaction in tegrator, incr eased r un-time sp eed, but gr eater er ror. You c an also set the chemistr y agglomer ation par amet ers using the t ext user in terface (TUI) c ommand define/models/species/integration-parameters . Onc e you enable agglomer ation chemistr y, ANSY S Fluen t prompts y ou f or Agglomerate Chemistry Error Tolerance and Agglomerate Chemistry Temperature Bin . Enter the desir ed v alues or pr ess Enter to retain the default v alues of 0.02 for Agglomerate Chemistry Error Tolerance and 10 for Agglomerate Chemistry Temperature Bin . More inf ormation c an b e found in Chemistr y Agglomer ation in the Fluent Theor y Guide . Imp ortant The solution accur acy can b e impr oved b y decr easing the t oler ances. Gener ally, it should not b e nec essar y to reduc e the t oler ances b elow 0.01 and 10 K. 20.4. Dimension Reduc tion Detailed k inetic mechanisms t ypic ally c ontain a multitude of in termedia te sp ecies tha t far e xceed the numb er of major fuel, oxidiz er, and pr oduc t sp ecies . Chemic al mechanism Dimension Reduc tion reduc es the numb er of in termedia te sp ecies tr ansp ort equa tions (c alled r epresen tative sp ecies) tha t are solv ed, and r econstr ucts the ‘unrepresen ted’ species using chemic al equilibr ium assumptions . Imp ortant Since ANSY S Fluen t is limit ed t o a maximum of 700 tr ansp orted sp ecies , the main use of Dimension Reduc tion is to enable simula tion with chemic al mechanisms c ontaining mor e than 700 sp ecies . Follow these st eps t o use Dimension Reduc tion : •Imp ort your CHEMKIN mechanism. Note tha t you c an imp ort CHEMKIN mechanisms tha t contain mor e than 700 sp ecies . •Click the Integration P aramet ers butt on in the Species M odel dialo g box, and enable Dimension Reduc tion . •Set the Numb er of Repr esen ted S pecies .This must b e gr eater than 10 and less than the numb er of sp ecies in the full mechanism. The Numb er of Repr esen ted S pecies must also b e less than 700 minus the numb er of unr epresen ted elemen ts (the numb er of chemic al elemen ts in the unr epresen ted sp ecies). A lar ger Numb er of Repr esen ted S pecies will incr ease accur acy, but also incr ease c omputa tional e xpense .The default of 12 has b een chosen t o pr ovide a go od compr omise b etween accur acy and sp eed. •Selec t the Full M echanism M aterial N ame , which is t ypic ally the name of the CHEMKIN mechanism tha t you imp orted. ANSY S Fluen t can st ore se veral imp orted CHEMKIN mechanisms in diff erent mix ture ma terials Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1802Using C hemistr y Accelerationwhose mechanisms y ou ar e not using . However, sinc e mechanisms ar e typic ally lar ge, you should delet e unused mix tures to reduc e memor y requir emen ts. •Set the b oundar y and initial fuel and o xidiz er, as w ell as pr oduc t species , as r epresen ted sp ecies .These ar e set in the Fuel/O xidiz er S pecies list. Note tha t you c an force other sp ecies t o be represen ted b y selec ting them her e. Species of in terest, esp ecially sp ecies tha t are not near chemic al equilibr ium, such as p ollutan ts, and their asso ciated in termedia te sp ecies in the mechanism should also b e included . Intermedia te sp ecies that occur in lar ge mass fr actions r elative to the fuel and o xidiz er sp ecies should b e included , as w ell as species imp ortant in the chemic al pa thw ay. For e xample , for methane c ombustion in air , CH3 should b e in- cluded as a r epresen ted sp ecies sinc e CH4 pyrolizes to CH3 first. •Click Calcula te Reduc ed D imension M ixture.This will cr eate a new mix ture ma terial c alled reduced- dimension-mixture , which c ontains the r epresen ted sp ecies as w ell as pr oxy ’species ’ for the unr epres- ented elemen ts.These unr epresen ted elemen ts ha ve “u" pr epended t o the elemen t name .You should never rename the r educ ed-dimension-mix ture mix ture ma terial, or selec t another mix ture as the ac tive material, while Dimension Reduc tion is enabled . •Continue with the setup , solution, and p ostpr ocessing as f or other detailed chemistr y cases . Note tha t the boundar y and initial mass fr action of unr epresen ted elemen ts should alw ays be zero.The en tries f or the unrepresen ted elemen t mass fr actions ar e disabled in the ANSY S Fluen t GUI. For p ostpr ocessing , the unr epresen ted elemen ts ar e available in the Species list as the elemen t name with “u" pr epended . All sp ecies in the full mechanism, consisting of b oth r epresen ted and unr epresen ted species , are available in the Full M echanism S pecies ... categor y of the p ostpr ocessing dialo g boxes. After y ou obtain a pr eliminar y solution with Dimension Reduc tion , it is r ecommended tha t you check the magnitude of all unr epresen ted sp ecies , which ar e available in the Full M echanism S pecies ... option in the Contours dialo g box. If the mass fr action of an y unr epresen ted sp ecies is lar ger than other r ep- resen ted sp ecies , you should r epeat the simula tion with this sp ecies included in the r epresen ted sp ecies list. In tur n, the mass fr action of all unr epresen ted elemen ts should decr ease . Note Note tha t Dimension Reduc tion is only a vailable with ISA T.Dimension Reduc tion is initially compar able in sp eed t o a simula tion with the full mechanism, but it erations b ecome signi- ficantly fast er a t later times when the ISA T table is p opula ted. For inf ormation ab out the theor y of this option, see Chemic al M echanism D imension R educ tion in the Fluent Theor y Guide . 20.5. Using D ynamic C ell C lust ering The D ynamic C ell C lustering (DC C) metho d is a vailable with the ANSY S CHEMKIN-CFD solv er. DCC gr oups computa tional c ells with similar t emp eratures, pressur es, and initial sp ecies mass fr actions in to clust ers. To use the DC C metho d, selec t Dynamic C ell C lust ering in the Integration P aramet ers dialo g box. The f ollowing par amet ers ar e available f or c ontrolling d ynamic c ell clust ering: •Max.Temp erature Dispersion (default =10 K) •Max. Equiv . Ratio D ispersion (default =0.05) 1803Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic C ell C lustering•Max. Clust erization (default = 10) and Min. Clust erization (default = 0) These par amet ers limit the numb er of gener ated clust ers and allo cate the r equir ed amoun t of memor y in your analy sis. •Reac tants Threshold (mass fr action) (default = 1e-09) If the c omput ed v alue of the sp ecies mass fr action is ab ove the sp ecified thr eshold , then the solv er calcula tes the clust erization par amet ers; other wise , it is c onsider ed t o be zero. The default v alues f or these par amet ers ha ve been f ound t o pr ovide accur ate results f or a wide r ange of c ombustion c ases .Varying these par amet ers ma y aff ect the c omputa tional c ost. For e xample , reducing maximum t emp erature and equiv alenc e ratio of disp ersions incr eases the numb er of clust ers, which leads t o a higher CPU c ost. For back ground inf ormation ab out DC C, refer to Dynamic C ell C lustering with ANSY S Fluen t CHEMKIN- CFD S olver in the Fluent Theor y Guide . 20.6. Using D ynamic A daptiv e Chemistr y with ANSY S Fluen t CHEMKIN- CFD S olver Note Dynamic A daptiv e Chemistr y is not c ompa tible with ISA T. The Dynamic A daptiv e Chemistr y metho d is c ontrolled b y the f ollowing par amet ers: •DAC Error Toler anc e: Controls the le vel of accur acy. A lar ger t oler ance would t end t o lo wer the accur acy but migh t sp eed up the c omputa tion. The default v alue f or DA C er ror toler ance is 0.001, which should b e suitable f or most c ases . •DAC tar get sp ecies: Are the initial sp ecies t o be tracked b y the DA C algor ithm. You c an selec t the tar get sp ecies f or y our analy sis in the Selec t DA C Target S pecies dialo g box that op ens when y ou click Selec t Target S pecies in the Integration P aramet ers dialo g box. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1804Using C hemistr y AccelerationFigur e 20.2: The Selec t DA C Target S pecies Dialo g Box For b oth diesel and gasoline sur rogate fuels , CO, HO2, and fuel sp ecies ar e an eff ective choic e for the tar get sp ecies ( 321 and 322). By default , only co and ho2 are selec ted as the DA C tar get species .You must also selec t fuel sp ecies f or y our analy sis. To mo dify the DA C tar get sp ecies list: –To remo ve the sp ecies fr om the Selec ted S pecies multiple-selec tion list , selec t it and click Remo ve. The sp ecies will b e mo ved fr om the Selec ted S pecies list t o the Unselec ted S pecies list. –To add the sp ecies back t o the Selec ted S pecies list, selec t it in the Unselec ted S pecies multiple- selec tion list and click Add.The sp ecies will b e mo ved fr om the Unselec ted S pecies list t o the Selec- ted S pecies list. For inf ormation ab out the theor y of this metho d, see Dynamic A daptiv e Chemistr y with ANSY S Fluen t CHEMKIN-CFD S olver in the Fluent Theor y Guide . 1805Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using D ynamic A daptiv e Chemistr y with ANSY S Fluen t CHEMKIN-CFD S olverRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1806Chapt er 21: Modeling E ngine Ignition This chapt er discusses ho w to use the engine ignition mo dels a vailable in ANSY S Fluen t in the f ollowing sections . For inf ormation ab out the theor y behind these ignition mo dels , see Engine Ignition in the Theor y Guide . 21.1. Spark Model 21.2. Autoignition M odels 21.3. Crevice Model 21.1. Spark M odel The spar k mo del in ANSY S Fluen t will b e descr ibed in the c ontext of the pr emix ed and par tially pr emix ed combustion mo dels , including the sp ecies tr ansp ort mo del. For inf ormation r egar ding the theor y of this mo del, see Spark Model in the Theor y Guide . Information r egar ding the use of this mo del is detailed in the f ollowing sec tions: 21.1.1. Using the S park Model 21.1.2. Using the ECFM S park Model 21.1.1. Using the S park M odel You c an mo del a single spar k or multiple spar ks.To use the spar k mo del, perform the f ollowing st eps: 1.Selec t Transien t from the Time list in the Gener al task page (or fr om the Gener al → Analy sis Type in the tr ee). 2.In the Species M odel dialo g box, selec t one of the f ollowing r eaction mo dels: Setup → Models → Species Edit... •Under Model, selec t Species Transp ort, and under Reac tions , enable Volumetr ic. •Under Model, selec t Premix ed M odel with the C Equa tion or G Equa tion mo del enabled . See Setting Up the C-E qua tion and G-E qua tion M odels (p.1751 ) for mor e inf ormation. The Spar k Ignition mo del will no w app ear in the Models task page and under the Models tree item. Imp ortant When y ou r ead in a R14.5 c ase file , ANSY S Fluen t will r evert to the R14.5 spar k mo del by default. To swit ch t o the cur rent spar k mo del, you c an either •open the Spar k Ignition dialo g box, or •use the TUI define/models/species/spark-model command . 1807Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.You c an also use the TUI define/models/species/spark-model command t o revert back t o the R14.5 spar k mo del. 3.Define spar ks for y our c ase using the Spar k Ignition dialo g box (see Figur e 21.1: The S park Ignition D ialog Box (p.1808 )). Setup → Models → Species → Spar k Ignition Edit... Figur e 21.1: The S par k Ignition D ialo g Box 4.Specify the Numb er of S par ks you w ould lik e to include in y our simula tion. You c an define up t o 16 spar ks. 5.While y ou c an define se veral spar ks, you c an cho ose which ones t o tur n on using the On option. 6.Enter the Name of the spar k, or simply k eep the default name . 7.Click the Define ... butt on t o op en the Set S par k Ignition dialo g box (Figur e 21.2: The S et Spark Ignition Dialog Box (p.1809 )), wher e you will set the par amet ers of the selec ted spar k ignition mo dels . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1808Modeling Engine IgnitionFigur e 21.2: The S et S par k Ignition D ialo g Box 8.Set the spar k mo del par amet ers. •Set X, Y, and Z c oordina tes of the spar k center and the Initial R adius of the spar k kernel in the Spar k Location group b ox. •Enter Start Time and Duration in the Spar k Paramet ers group b ox. Imp ortant When the in-c ylinder mo del is tur ned on, the Start Time is en tered in cr ank angle degr ees inst ead of sec onds , while the spar k Duration is still in sec onds .The v alue you en ter for Start Time is for one c omplet e engine c ycle. In subsequen t cycles, the spar k is enabled acc ording t o Equa tion 11.30 (p.1339 ), wher e corresponds t o the spar k star t crank angle . •(optional) S et Energy to a p ositiv e value if y ou w ant to mo del the higher t emp erature levels within the spar k kernel. The ener gy input will b e evenly distr ibut ed acr oss the sp ecified spar k dur ation. This ener gy is not r equir ed t o initia te combustion. The spar k mo del will c ontrol the spar k kernel gr owth and c om- bustion pr ogress. For this r eason the default ener gy input is z ero. If you sp ecify e xtra ener gy her e, it will r aise the k ernel t emp erature beyond tha t giv en b y the c ombustion pr ocess. •Selec t the Flame S peed M odel from the dr op-do wn list. For details of these mo dels see Spark Model Theor y in the Fluent Theor y Guide . 1809Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Spark Model21.1.2. Using the ECFM S park M odel When the Extended C oher ent Flamelet M odel (see Setting U p the Ex tended C oher ent Flame M od- el (p.1754 )) is selec ted in the Species M odel dialo g box, the Set S par k Ignition dialo g box will e xhibit additional ECFM S par k M odel options , as sho wn in Figur e 21.3: The S et S park Ignition D ialog Box Displa ying the ECFM S park Model Options (p.1810 ). Figur e 21.3: The S et S par k Ignition D ialo g Box Displa ying the ECFM S par k M odel Options In addition t o sp ecifying the v ariables men tioned in Using the S park Model (p.1807 ), you c an selec t from one of the f ollowing ECFM S park mo dels: •Turbulen t •Zimon t (default) •Constan t Value •User D efined S igma S our ce This c ontrols the w ay in which the v alue of the flame sur face densit y is c alcula ted. More details ar e given in ECFM S park Model Variants in the Fluent Theor y Guide . If you cho ose Constan t Value you will b e requir ed t o sp ecify the v alue f or flame sur face densit y. If you cho ose User D efined S igma S our ce you will need t o cho ose the ho oked user-defined func tion to apply a cust om sour ce term to the ECFM equa tion within the v olume of the spar k ignition k ernel. For mor e detail ab out this user-defined func tion, refer to Hooking DEFINE_ECFM_SPARK_SOURCE UDFs in the Fluent C ustomization Manual . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1810Modeling Engine Ignition21.2. Autoignition M odels Autoignition phenomena in engines ar e due t o the eff ects of chemic al kinetics of the r eacting flo w inside the c ylinder .There ar e two types of aut oignition mo dels c onsider ed in ANSY S Fluen t: •knock mo del in spar k-ignit ed (SI) engines •ignition dela y mo del in diesel engines For inf ormation r egar ding the theor y behind aut oignition mo dels , see Autoignition M odels in the Theor y Guide .Using the A utoignition M odels (p.1811 ) descr ibes ho w to use the aut oignition mo dels in ANSY S Fluen t. 21.2.1. Using the A utoignition M odels To use the aut oignition mo del, perform the f ollowing st eps: 1.Selec t Transien t from the Time list in the Gener al task page (or fr om the Gener al → Analy sis Type in the tr ee). 2.Selec t an appr opriate reaction mo del in the Species M odel dialo g box. Setup → Models → Species Edit... 3.The mo dels in the Species M odel dialo g box tha t are compa tible with the aut oignition mo del ar e Species Transp ort,Premix ed C ombustion , and Partially P remix ed C ombustion . The Autoignition mo del will no w app ear in the Models task page and under the Models tree item. Imp ortant •If you selec t Species Transp ort, you must also enable the Volumetr ic option in the Reac tions group b ox. •The Premix ed C ombustion and Partially P remix ed C ombustion mo dels ar e only a vailable for turbulen t flo ws using the pr essur e-based solv er. 4.Selec t the A utoignition mo del. Setup → Models → Species → Autoignition Edit... •If Species Transp ort is selec ted in the Species M odel dialo g box, you c an only selec t the Ignition Delay M odel. 1811Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Autoignition M odelsFigur e 21.4: The Ignition D elay M odel in the A utoignition M odel D ialo g Box •If Premix ed C ombustion is selec ted in the Species M odel dialo g box, you c an only selec t the Knock Model. Figur e 21.5: The K nock M odel in the A utoignition M odel D ialo g Box •If Partially P remix ed C ombustion is selec ted in the Species M odel dialo g box, you c an selec t either the Knock M odel or the Ignition D elay M odel. 5.When the Ignition D elay M odel is enabled , the dialo g box expands t o include the mo deling par amet ers for this mo del ( Figur e 21.6: The Ignition D elay Model f or the P artially P remix ed C ombustion M odel (p.1813 )). The t wo correlation options tha t exist with this mo del ar e Hardenbur g and Gener aliz ed. Depending on which c orrelation option is selec ted, the appr opriate mo deling par amet ers will app ear in the dialo g box. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1812Modeling Engine IgnitionFigur e 21.6: The Ignition D elay M odel f or the P artially P remix ed C ombustion M odel •The Hardenbur g option is t ypic ally used f or hea vy dut y diesel engines .With this option, the f ollowing paramet ers ar e available: –Pre-Exponen tial –Pressur e Exponen t –Activation E nergy –Cetane N umb er For the Species Transp ort mo del, Fuel S pecies is selec ted fr om the dr op-do wn list. •The Gener aliz ed option is descr ibed b y Equa tion 13.10 in the Theor y Guide .With this option, the f ol- lowing par amet ers ar e available: –Pre-Exponen tial –Temp erature Exponen t –Activation E nergy –RPM E xponen t –Pressur e Exponen t –Equiv alenc e Ratio E xponen t –Octane N umb er –Octane N umb er E xponen t For the Species Transp ort mo del, Fuel S pecies is selec ted fr om the dr op-do wn list. 1813Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Autoignition M odelsDefault v alues of these par amet ers c an b e found in Default Values of the Variables in the Har denbur g Correlation in the Fluent Theor y Guide . 6.When the Knock M odel is enabled , the dialo g box expands t o include mo deling par amet ers f or this model ( Figur e 21.7: The K nock M odel with the P artially P remix ed C ombustion M odel Enabled (p.1814 )).The two correlation options tha t exist with this mo del ar e Douaud and Gener aliz ed. Depending on which correlation option is selec ted, the appr opriate mo deling par amet ers will app ear in the dialo g box. Figur e 21.7: The K nock M odel with the P artially P remix ed C ombustion M odel E nabled •The Douaud option is used f or k nock in SI engines .The mo deling par amet ers tha t are sp ecified in the Autoignition M odel dialo g box for this option ar e the Pre-Exponen tial,Pressur e Exponen t,Activation Temp erature,Octane N umb er, and Octane E xponen t (Equa tion 13.9 in the Theor y Guide ). •The Gener aliz ed option ( Equa tion 13.10 in the Theor y Guide ) in the k nock mo del r equir es the same paramet ers as in the ignition dela y mo del. 21.3. Crevice M odel For inf ormation r egar ding the theor y behind the cr evice mo del, see Crevice M odel in the Theor y Guide . Using the cr evice mo dels in ANSY S Fluen t are descr ibed in the f ollowing sec tions: 21.3.1. Using the C revice Model 21.3.2. Crevice Model S olution D etails 21.3.3. Postpr ocessing f or the C revice Model 21.3.1. Using the C revice M odel An optic al experimen tal engine [28] (p.4006 ) is used b elow to sho w a w orking e xample of ho w to use the cr evice mo del as it is implemen ted in ANSY S Fluen t.The mesh a t ten cr ank angle degr ees b efore top c enter is sho wn in Figur e 21.8: Exp erimen tal Engine M esh (p.1815 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1814Modeling Engine IgnitionFigur e 21.8: Experimen tal E ngine M esh The f ollowing e xample sho ws the nec essar y steps t o enable the cr evice mo del f or a t ypic al in-c ylinder flow. 1.From the > pr ompt , enter the define/models menu b y using the f ollowing t ext command: define → models 2.Enable the cr evice mo del, as f ollows: /define/models crevice-model? Enable crevice model? [no] yes /define/models acoustics/ multiphase/ species/ addon-module noniterative-time-advance? steady? axisymmetric? nox? unsteady-1st-order? crevice-model-controls/ radiation/ unsteady-2nd-order? crevice-model? solidification-melting? viscous/ dpm/ solver/ energy? soot? frozen-flux? sox? 3.Enter the r ing pack geometr y: /define/models crevice-model-controls Cylinder bore (m) [0.1] 0.1397 Piston to bore clearance (m) [3.0e-5] 5.08e-05 Piston crevice temperature (K) [400] 433 Piston sector angle (deg) [360] 45 1815Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Crevice Model Ring discharge coefficient [0.8] 0.7 Pressure in crankcase (exit pressure) (Pa) [101325] Write out crevice data to a file? [no] yes output file name ["crev.out"] Available wall threads are: (wall.1 wall wall-8) Leaking wall [] wall.1 Shared boundary [] wall-8 Selected boundary threads : (wall.1 wall-8) Use these zones? [yes] yes Solve crevice model ? [no] yes Number of rings [3] Width of ring number 0 is: [0.00375] Thickness of ring number 0 is: [0.0015] Spacing of ring number 0 is: [0.008] Land Length for ring number 0 is: [0.00391] Top Gap of ring number 0 is: [6e-05] Middle Gap of ring number 0 is: [4e-05] Bottom Gap of ring number 0 is: [6e-05] Width of ring number 1 is: [0.00375] Thickness of ring number 1 is: [0.0015] Spacing of ring number 1 is: [0.008] Land Length for ring number 1 is: [0.00391] Top Gap of ring number 1 is: [6e-05] Middle Gap of ring number 1 is: [4e-05] Bottom Gap of ring number 1 is: [6e-05] Width of ring number 2 is: [0.00375] Thickness of ring number 2 is: [0.0015] Spacing of ring number 2 is: [0.00391] Land Length for ring number 2 is: [0.00391] Top Gap of ring number 2 is: [6e-05] Middle Gap of ring number 2 is: [4e-05] Bottom Gap of ring number 2 is: [6e-05] Initial conditions in ring pack Pressure 1 is: [4600623.5] Pressure 2 is: [4173522.5] Pressure 3 is: [3689110.5] Pressure 4 is: [3130620] Pressure 5 is: [2214841.8] A fast w ay to set up multiple r ings in the r ing pack is t o sp ecify only one r ing and en ter the geo- metr y. Onc e the r ing geometr y is en tered, invoke the crevice-model- controls menu a second time and sp ecify the numb er of r ings desir ed.When the numb er of r ings changes , the geometr y from the first r ing is c opied t o all subsequen t rings . Default v alues c an b e tak en f or the rest of the w ay thr ough the menu str ucture. A summar y of the cr evice mo del is pr inted out b y en tering the (crevice-summary) command at the c ommand pr ompt: >(crevice-summary) crevice/n-rings : 3 crevice/ring-width : (0.00375 0.00375 0.00375) crevice/ring-thickness : (0.0015 0.0015 0.0015) crevice/ring-mass : (0.00375 0.00375 0.00375) crevice/ring-spacing : (0.008 0.008 0.00391) crevice/land-length : (0.00391 0.00391 0.00391) crevice/top-ring-gap : (6e-05 6e-05 6e-05) crevice/mid-ring-gap : (4e-05 4e-05 4e-05) crevice/bot-ring-gap : (6e-05 6e-05 6e-05) crevice/piston-temperature : 433 crevice/sector-angle : 45 crevice/mid-gap-cd : 0.7 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1816Modeling Engine Ignition crevice/exit-pressure : 101325 crevice/threads : (5 6) names of crevice/threads : (wall.1 wall-8) crevice/unit-roundoff : 5.9604645e-08 crevice/piston-bore-clearance : 5.08e-05 crevice/write? : #t crevice/output-file : crev.out crevice/solve? : #t crevice/enabled? : #t crevice/pressures : (4600623.5 4173522.5 3689110.5 3130620 2214841) 21.3.2. Crevice M odel S olution D etails The under-r elaxa tion fac tor for the cr evice mo del sour ce terms c an b e found in the Solution C ontrols task page .The default v alue f or Crevice M odel S our ces is 0.8, which has b een f ound t o work well for mot ored engine simula tions . Onc e the cr evice mo del is enabled , the solution pr oceeds nor mally . Solution → Controls Solution → Initializa tion Solution → Run C alcula tion 21.3.3. Postpr ocessing f or the C revice M odel A plot of c ylinder mass with and without the cr evice mo del dur ing the mot ored engine simula tion is shown in Figur e 21.9: Cylinder M ass v s. Crank A ngle (p.1818 ).The r ate of mass loss fr om the cr evice is proportional t o the pr essur e diff erence between the c ylinder and the cr ankc ase pr essur e defined in the t ext interface. 1817Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Crevice ModelFigur e 21.9: Cylinder M ass v s. Crank A ngle A plot of c ylinder pr essur e with and without the cr evice mo del f or the same engine simula tion is sho wn in Figur e 21.10: Cylinder P ressur e vs. Crank A ngle (p.1819 ).The eff ect of the mass loss fr om the cr evice is to lo wer the p eak pr essur e in pr oportion t o the t otal mass loss fr om the c ylinder . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1818Modeling Engine IgnitionFigur e 21.10: Cylinder P ressur e vs. Crank A ngle 21.3.3.1. Using the C revice O utput F ile The pr essur e in the t op r ing land is defined as the c ylinder pr essur e (tha t is, the pr essur e in the c ells defining the r ing landing). Intermedia te pr essur es ar e available a t an y point dur ing the ANSY S Flu- ent session thr ough the (crevice-summary) command as pr eviously sho wn. If the optional da ta file output is chosen in the crevice-model-controls , the in termedia te pr essur es in the defined crevices ar e pr inted t o the file crev.out at the star t of each new time st ep.The f ormat of the file is as f ollows: # crank (deg) data-press[0...1...2...3...4...5...6] total_mdot 1.95500e+02 2.16650e+05 1.01325e+05 1.01325e+05 1.01325e+05 1.01325e+05 1.01325e+05 1.01325e+05 0.0 1.96000e+02 2.09945e+05 1.06794e+05 1.81553e+05 1.04111e+05 1.48582e+05 1.02202e+05 1.01325e+05 -1.6 1.96500e+02 2.17787e+05 1.13070e+05 1.88242e+05 1.07960e+05 1.53544e+05 1.03526e+05 1.01325e+05 -1.6 1.97000e+02 2.17434e+05 1.19065e+05 1.88060e+05 1.11705e+05 1.53475e+05 1.04830e+05 1.01325e+05 -1.6 1.97500e+02 2.17652e+05 1.24777e+05 1.88299e+05 1.15286e+05 1.53668e+05 1.06081e+05 1.01325e+05 -1.6 1.98000e+02 2.17937e+05 1.30215e+05 1.88594e+05 1.18711e+05 1.53900e+05 1.07283e+05 1.01325e+05 -1.6 wher e the first c olumn is the cur rent flo w time (or cr ank angle), and the ne xt columns ar e the ring pr essur es (wher e is the numb er of cr evice volumes , or ), including the fac e pr essur e on the cr evice cell, and the defined pr essur e at the cr evice exit.The final c olumn is the mass flo w past the t op r ing.This file is cur rently f ormatted so tha t it c an b e read in to the fr ee Gnuplot plotting pack age, which is a vailable a t www.gnuplot.info . To read the cr evice output file in to ANSY S Fluen t as a da ta file , you will need t o put each c olumn of the cr evice output file in its o wn individual file .The first thr ee lines of each c olumn of the da ta file should b e of the f ollowing f orm: 1819Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Crevice Model "Title" "X-Label" "Y-Label" 0 0 0 0 wher e the title , -lab el, and -lab el str ings ar e enclosed b y double quot es and the thir d line of the file c ontains f our z eros.The lines f ollowing the first thr ee lines of the file ar e the c olumns y ou w ant to plot. For e xample , to plot c olumn 1 v ersus c olumn 3 of the cr evice mo del output file in ANSY S Fluen t, you w ould en ter the f ollowing c ommands in a Linux t erminal: cat > crev_col_1_3.dat "Column 1 vs Column 3" "Crank Angle (deg)" "Pressure behind ring 1 (Pa)" 0 0 0 0 ctrl-d wher e ctrl-d is the end-of-file char acter made holding do wn the Ctrl key and pr essing d (Ctrl+d). To app end c olumns 1 and 3 t o this file , enter the f ollowing: tail +2 crev.out | awk ’{print $1, $3}’ >> crev_col_1_3.dat The file crev_col_1_3.dat can no w b e read in to ANSY S Fluen t using the File X Y Plot D ialog Box (p.3708 ). See XY Plots of F ile D ata (p.2869 ) for details ab out cr eating - plots . For Windo ws users , the file crev.out can b e imp orted in to Ex cel for plotting pur poses without an y mo dific ation. A Gnuplot plot of the pr essur e in the r ing pack cr evices for the ab ove engine simula tion is sho wn in Figur e 21.11: Crevice Pressur es (p.1821 ). After an initial tr ansien t period wher e the flo ws in the net work settle do wn, Figur e 21.11: Crevice Pressur es (p.1821 ) sho ws tha t the pr essur e in the r ing cr evices follows the c ylinder pr essur e in f orm, though with pr essur e magnitudes tha t are controlled b y the r ing pack geometr y. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1820Modeling Engine IgnitionFigur e 21.11: Crevice Pressur es 1821Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Crevice ModelRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1822Chapt er 22: Modeling P ollutan t Formation This chapt er discusses ho w to use the mo dels a vailable in ANSY S Fluen t for mo deling p ollutan t formation. For inf ormation ab out the theor y behind the mo dels in ANSY S Fluen t, see Pollutan t Formation in the Theor y Guide . Information is pr esen ted in the f ollowing sec tions: 22.1. NOx Formation 22.2. SOx Formation 22.3. Soot Formation 22.4. Using the D ecoupled D etailed C hemistr y Model 22.1. NO x Formation The f ollowing sec tions descr ibe ho w to use the NOx mo dels in ANSY S Fluen t. For inf ormation ab out the theor y behind the NOx mo dels in ANSY S Fluen t, see NOx Formation in the Theor y Guide . 22.1.1. Using the NO x Model 22.1.2. Solution S trategies 22.1.3. Postpr ocessing 22.1.1. Using the NO x M odel 22.1.1.1. Decoupled A nal ysis: Overview NOx concentrations gener ated in c ombustion sy stems ar e gener ally lo w. As a r esult , NOx chemistr y has negligible influenc e on the pr edic ted flo w field , temp erature, and major c ombustion pr oduc t concentrations . It follows tha t the most efficien t way to use the NOx mo del is as a p ostpr ocessor t o the main c ombustion c alcula tion. The r ecommended pr ocedur e is as f ollows: 1.Calcula te your c ombustion pr oblem using ANSY S Fluen t as usual. Imp ortant The pr emix ed c ombustion mo del is not c ompa tible with the NOx mo del. Imp ortant If you plan t o use the ANSY S Fluen t selec tive non-c atalytic r educ tion (SNCR) mo del f or NOx reduc tion, you must first include ammonia NH3 or ur ea C O(NH2)2 (dep ending up on which r eagen t is emplo yed) as a fluid sp ecies in the main c ombustion c alcula tion and define appr opriate sp ecies injec tions , as descr ibed la ter in this sec tion. See Defining 1823Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.the S pecies in the M ixture (p.1630 ) for details ab out adding sp ecies t o your mo del and Setting Initial C onditions f or the D iscrete Phase (p.1943 ) for details ab out cr eating injec- tions . 2.Enable the desir ed NOx mo dels (ther mal, prompt , fuel, and/or N2O in termedia te NOx, with or without rebur n), define the fuel str eams (f or pr ompt NOx and fuel NOx only), and set the appr opriate par amet ers, as descr ibed in this sec tion. Setup → Models → Species → NOx Edit... 3.Define the b oundar y conditions f or NO (and HCN, NH3, or N2O if nec essar y) at flo w inlets . Setup → Boundar y Conditions 4.(steady sta te only) In the Equa tions D ialog Box (p.3609 ), turn off the solution of all v ariables e xcept sp ecies NO (and HCN, NH3, or N2O, based on the mo del selec ted). Solution → Controls → Equa tions ... 5.(transien t cases only) In the Run C alcula tion task page , selec t Postpr ocess P ollutan ts and adjust Max Post I terations/T ime S tep as needed . Solution → Run C alcula tion 6.Perform calcula tions un til convergenc e (tha t is, until the NO—and HCN, NH3, or N2O, if solv ed—sp ecies residuals ar e below 10-6). Solution → Run C alcula tion 7.Review the mass fr actions of NO (and HCN, NH3, or N2O) b y gener ating gr aphic al plots or alphanumer ic reports in the usual w ay. 8.Save a new set of c ase and da ta files , if desir ed. File → Write → Case & D ata... Inputs sp ecific t o the c alcula tion of NOx formation ar e explained in the r emainder of this sec tion. 22.1.1.2. Enabling the NO x Mo dels To enable the NOx mo dels and set r elated par amet ers, you will use the NOx Model D ialog Box (p.3332 ) (for e xample ,Figur e 22.1: The NO x Model D ialog Box (p.1825 )). Setup → Models → Species → NOx Edit... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1824Modeling P ollutan t FormationFigur e 22.1: The NO x M odel D ialo g Box In the Formation tab , selec t the NOx mo dels under Pathw ays to be used in the c alcula tion of the NO and HCN, NH3, or N2O concentrations: •To enable ther mal NOx, turn on the Thermal NO x option. •To enable pr ompt NOx, turn on the Prompt NO x option. •To enable fuel NOx, turn on the Fuel NO x option. Imp ortant When using the non-pr emix ed c ombustion mo del, the f ollowing limita tion e xists f or the Fuel NO x option: –The Fuel NO x option is only a vailable if the DPM mo del is also enabled . •To enable the f ormation of NOx through N2O in termedia te, turn on the N2O In termedia te option. (Note that the N2O option will not app ear un til you ha ve enabled one of the other NO mo dels list ed ab ove.) Your selec tion(s) under Pathw ays will enable the c alcula tion of ther mal, prompt , fuel, and/or N2O- intermedia te NOx in acc ordanc e with the chemic al kinetic mo dels descr ibed in Thermal NO x Formation through NOx Formation fr om In termedia te N2O in the Theor y Guide . Mean NO f ormation r ates will be comput ed dir ectly fr om mean c oncentrations and t emp erature in the flo w field . 1825Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.NOx Formation22.1.1.3. Defining the F uel Str eams When mo deling fuel NOx formation, ANSY S Fluen t allo ws you t o define up t o thr ee separ ate fuel streams , and t o selec t fuel sour ces for each fuel str eam. You c an define multiple fuel str eams t o include in y our mo del with the f ollowing c onfigur ations: •Solid and liquid fuels (c ombusting par ticle and dr oplet) b oth c ontributing t o fuel NOx. •Two or thr ee solid fuels with diff erent -content and NOx mo del par amet ers (t wo or thr ee c ombusting particles), for e xample c oal blends , coal-biomass c ofiring, and so on. •Two or thr ee liquid fuels with diff erent -content and NOx mo del par amet ers (t wo or thr ee dr oplet or multic omp onen t par ticles). •Gas and solid (or dr oplet) fuel b oth c ontributing t o fuel NOx. In addition, you c an mo del one solid fuel c ontributing t o NOx in the pr esenc e of another r e- acting solid par ticle not c ontaining an y (for e xample , sorb ent injec tion in a c oal fur nace or calcina tion r eaction in c emen t kiln) b y sp ecifying the ac tive fuel sour ce for NOx formation. For this c onfigur ation, you will not need t o define multiple fuel str eams in y our mo del. If Fuel NO x is enabled in the Pathw ays group b ox in the Formation tab , perform the f ollowing st eps to define multiple fuel str eams: 1.Specify the Numb er of F uel S treams in the Fuel S treams group b ox. Note You ar e allo wed up t o thr ee separ ate fuel str eams . 2.Define the first fuel str eam. a.Selec t the fuel str eam t o be defined b y using the ar row keys of the Fuel S tream ID field . b.Selec t the Fuel Type in the Fuel tab f or the Formation M odel P aramet ers. c.If your Fuel Type is Liquid or Solid , selec t the N sour ces fr om the Fuel S our ces list. •If the Fuel Type is Solid and y ou ha ve defined multiple injec tions with diff erent combusting par ticle materials in y our r eacting flo w calcula tion, the a vailable c ombusting par ticle ma terials will b e list ed in the Fuel S our ces list. Selec t one or mor e ma terials fr om the list t o be included as fuel sour ces in the Fuel NO x calcula tion. Your selec tion will b e used t o det ermine the char bur nout r ate and volatile r elease r ate in the c oal fuel NOx formation r ate mo dels descr ibed in Fuel NO x from Coal in the Theor y Guide . Make sur e to deselec t all c ombusting par ticle ma terials tha t do not contribut e to NOx. •If the Fuel Type is Liquid and y ou ha ve defined multiple injec tions with diff erent droplet or mul- ticomp onen t par ticle ma terials in y our r eacting flo w calcula tion, the a vailable ma terials will b e listed in the Fuel S our ces list. Selec t one or mor e ma terials fr om the list t o be included as fuel sour ces in the Fuel NO x calcula tion. Your selec tion will b e used t o det ermine the fuel r elease r ate Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1826Modeling P ollutan t Formation in the liquid fuel NOx formation r ate mo dels descr ibed in Fuel NO x from In termedia te Hydrogen Cyanide (HCN) and Fuel NO x from In termedia te Ammonia (NH3) in the Theor y Guide . Make sur e to deselec t all dr oplet and multic omp onen t ma terials tha t do not c ontribut e to NOx. d.If you ar e also mo deling Prompt NO x, selec t the fuel sp ecies fr om the Fuel S pecies list. You c annot selec t mor e than 5 fuel sp ecies f or each fuel str eam, and the t otal numb er of fuel sp ecies selec ted for all the fuel str eams c ombined c annot e xceed 10. You c an define the same , or diff erent Fuel S pecies , Fuel C arb on N umb er and Equiv alenc e Ratio for each str eam. The Fuel C arb on N umb er and Equiv alenc e Ratio can b e mo dified in the Prompt tab under Formation M odel P aramet ers. e.If the Fuel Type in y our mo del is Gas, selec t one or mor e ma terials fr om the Fuel S pecies list. Your selec tion will b e used t o det ermine the mean limiting r eaction r ate in the gaseous fuel NOx formation r ate mo dels descr ibed in Fuel NO x from In termedia te Hydrogen C yanide (HCN) and Fuel NOx from In termedia te Ammonia (NH3) in the Theor y Guide . If you ar e also mo deling Prompt NO x formation, the same fuel selec tion will apply also f or the pr ompt NOx mo del. f.Set the other par amet ers asso ciated with y our selec ted pa thw ay(s) in the Prompt and/or Fuel tabs under Formation M odel P aramet ers. See Setting P rompt NO x Paramet ers (p.1829 ) and Setting F uel NOx Paramet ers (p.1830 ) for details . 3.Repeat steps 2.(a)–2.(f ) for each additional fuel str eam. Imp ortant •The gaseous fuel option is a vailable only when the sp ecies mo del is enabled . •Imp ortant consider ations should b e made when r eading c ase and da ta files set up in a v ersion of ANSY S Fluen t 14.5 or ear lier: –When r eading a c ase and da ta file with multiple injec tion ma terials tha t was set up in ANSY S Fluen t version 14.5 or ear lier, ANSY S Fluen t will initializ e the injec tion ma terial sp ecific fuel N sour ces for the fuel NOx mo del. ANSY S Fluen t will p erform a DPM it eration when the flo w iterations ar e initia ted. –When r eading a c ase file tha t was set up in a v ersion older than ANSY S Fluen t 14.5 with multiple fuel str eams defined f or the Fuel NO x mo del, you must r eview the setup and selec t the N sour ces fr om the Fuel S our ces list. 1827Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.NOx FormationFigur e 22.2: The NO x M odel D ialo g Box Displa ying the F uel S treams 22.1.1.4. Specifying a User -Defined F unc tion for the NO x Rate You c an cho ose t o sp ecify a user-defined func tion f or the r ate of NOx produc tion. By default , the r ate retur ned fr om the UDF is added t o the r ate retur ned fr om the standar d NOx produc tion options , if any are selec ted.You also ha ve the option of r eplacing an y or all of ANSY S Fluen t’s NOx rate calcula tions with y our o wn user-defined NOx rate. In addition t o or inst ead of using the UDF t o sp ecify the NOx rate, you c an use it t o sp ecify cust om values f or the maximum limit ( ) tha t is used f or the in tegration of the t emp erature PDF (when temp erature is acc oun ted f or in the turbulenc e in teraction mo deling). To use a UDF t o add a r ate to ANSY S Fluen t’s NOx rate calcula tions , you must c ompile and load the desir ed func tion, and then selec t it fr om the NOx Rate drop-do wn list in the User-D efined F unc tions group b ox in the Formation tab . After y ou ha ve selec ted the UDF , you ha ve the f ollowing options: •You c an sp ecify tha t your cust om r ate is added t o the ANSY S Fluen t NOx rate calcula tions , by retaining the default selec tion of Add t o Fluen t Rate in the UDF R ate group b ox for the appr opriate NOx formation pathw ay(s) (f or e xample , in the Fuel tab). •You c an r eplac e the ANSY S Fluen t NOx rate calcula tions with y our cust om r ate, by selec ting Replac e Fluen t Rate in the UDF R ate group b ox for the appr opriate NOx formation pa thw ay(s) (f or e xample , in the Fuel tab). •You c an sp ecify cust om v alues f or , by selec ting user-defined from the Tmax Option drop-do wn list in the Turbulenc e In teraction M ode tab . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1828Modeling P ollutan t FormationSee the Fluen t Customiza tion M anual for details ab out user-defined func tions . 22.1.1.5. Setting Thermal NO x Paramet ers The routines emplo y thr ee metho ds for c alcula tion of ther mal NOx (as descr ibed in Metho d 1: Equilibr ium A pproach in the Theor y Guide ).You will sp ecify the metho d to be used in the Thermal tab, under Formation M odel P aramet ers in the NOx Model D ialog Box (p.3332 ): •To cho ose the equilibr ium metho d, selec t equilibr ium in the [O] M odel drop-do wn list. •To cho ose the par tial equilibr ium metho d, selec t par tial-equilibr ium in the [O] M odel or [OH] M odel drop-do wn list. •To use the pr edic ted O and/or OH c oncentration, selec t instan taneous in the [O] M odel or [OH] M odel drop-do wn list. Imp ortant Note tha t the ur ea mo del uses the [OH] mo del. If you ho oked a user-defined func tion in the Formation tab , you c an mak e a selec tion in the UDF Rate group b ox to sp ecify the tr eatmen t of the user-defined NOx rate: •Selec t Replac e Fluen t Rate to replac e ANSY S Fluen t’s ther mal NOx rate calcula tions with the cust om NOx rate pr oduced b y your UDF . •Selec t Add t o Fluen t Rate to add the cust om NOx rate pr oduced b y your UDF t o ANSY S Fluen t’s ther mal NOx rate calcula tions . 22.1.1.6. Setting P rompt NO x Paramet ers Prompt NOx formation is pr edic ted using Equa tion 14.26 and Equa tion 14.28 in the Theor y Guide . For each fuel str eam sp ecified in the Fuel S tream ID field in the Formation tab , set the par amet ers in the Prompt tab under Formation M odel P aramet ers in the NOx Model D ialog Box (p.3332 ) in the following manner : •Set the Fuel C arb on N umb er to sp ecify the numb er of c arbon a toms p er fuel molecule . •Set the Equiv alenc e Ratio as f ollows: (22.1) If you ho oked a user-defined func tion in the Formation tab , you c an mak e a selec tion in the UDF Rate group b ox to sp ecify the tr eatmen t of the user-defined NOx rate: •Selec t Replac e Fluen t Rate to replac e ANSY S Fluen t’s prompt NOx rate calcula tions with the cust om NOx rate pr oduced b y your UDF . •Selec t Add t o Fluen t Rate to add the cust om NOx rate pr oduced b y your UDF t o ANSY S Fluen t’s prompt NOx rate calcula tions . 1829Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.NOx Formation22.1.1.7. Setting F uel NO x Paramet ers When using the fuel NOx mo del, you must set the par amet ers in the Fuel tab under Formation Model P aramet ers for each fuel str eam sp ecified in the Fuel S tream ID field in the Formation tab . If you ho oked a user-defined func tion in the Formation tab , you c an mak e a selec tion in the UDF Rate group b ox to sp ecify the tr eatmen t of the user-defined NOx rate: •Selec t Replac e Fluen t Rate to replac e ANSY S Fluen t’s fuel NOx rate calcula tions with the cust om NOx rate produced b y your UDF . •Selec t Add t o Fluen t Rate to add the cust om NOx rate pr oduced b y your UDF t o ANSY S Fluen t’s fuel NOx rate calcula tions . If ther e is no NOx rate UDF or if y ou selec ted Add t o Fluen t Rate, you must define fuel par amet ers. To begin, specify the fuel t ype in the f ollowing manner : •For solid fuel NOx, selec t Solid under Fuel Type. •For liquid fuel NOx, selec t Liquid under Fuel Type. •For gaseous fuel NOx, selec t Gas under Fuel Type. Note tha t you c an use only one of the fuel t ypes for a giv en fuel str eam. The Gas option is a vailable only when the Species Transp ort mo del is enabled (see Enabling S pecies Transp ort and R eactions and C hoosing the M ixture M aterial (p.1616 )). 22.1.1.7.1. Setting G aseous and Liquid F uel NO x Paramet ers If you ha ve selec ted Gas or Liquid as the Fuel Type, you must also sp ecify the f ollowing: •Selec t the in termedia te sp ecies ( hcn ,nh3 , or hcn/nh3/no ) in the N In termedia te drop-do wn list. •Set the c orrect mass fr action of nitr ogen in the fuel (k g nitr ogen p er kg fuel) in the Fuel N M ass F raction field . •Specify the o verall fr action of the fuel N, by mass , tha t will b e converted t o the in termedia te sp ecies and/or pr oduc t NO in the Conversion F raction field .The Conversion F raction for the N In termedia te has a default v alue of 1. Therefore, any remaining N will not c ontribut e to NOx formation. This is based on the assumption tha t the r emaining v olatile N will c onvert to gas phase nitr ogen. However, this has very little eff ect on the o verall mass fr action of gas phase nitr ogen. Therefore, you do not ha ve to solv e for nitr ogen sp ecies when solving p ollutan t transp ort equa tions . •If you selec ted hcn/nh3/no as the in termedia te, specify the fr action of the c onverted fuel N, by mass , that will b ecome hcn and nh3 under Partition F ractions .The fr action of fuel N tha t will b ecome NO will be calcula ted b y the r emainder . Note tha t setting a par tition fr action of 0 f or b oth HCN and NH3 is equiv alen t to assuming tha t all fuel N is c onverted t o the final pr oduc t NO , wher eas a par tition fr action of 0 f or HCN and 1 f or NH3 is the same as selec ting nh3 as the in termedia te. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1830Modeling P ollutan t FormationANSY S Fluen t will use Equa tion 14.31 and Equa tion 14.32 in the Theor y Guide (for HCN) or Equa- tion 14.42 and Equa tion 14.43 in the Theor y Guide (for NH3) to pr edic t NO f ormation f or a gaseous or liquid fuel. Imp ortant Note tha t ther e is a limita tion tha t must b e consider ed when defining mor e than one liquid fuel str eam. See Defining the F uel S treams (p.1826 ) for details . 22.1.1.7.2. Setting S olid (C oal) F uel NO x Paramet ers For solid (c oal) fuel, ANSY S Fluen t will use Equa tion 14.55 and Equa tion 14.56 in the Theor y Guide (for HCN) or Equa tion 14.62 and Equa tion 14.63 in the Theor y Guide (for NH3) to pr edic t NO f ormation. Several inputs ar e requir ed f or the c oal fuel NOx mo del as f ollows: •Selec t the in termedia te sp ecies ( hcn ,nh3 , or hcn/nh3/no ) in the N In termedia te drop-do wn list. •Specify the mass fr action of nitr ogen in the v olatiles in the Volatile N M ass F raction field . •Specify the o verall fr action of the v olatile , by mass , tha t will b e converted t o the in termedia te sp ecies and/or pr oduc t NO in the Conversion F raction field . •If you selec ted hcn/nh3/no as the v olatile N in termedia te, specify the fr action of the c onverted v olatile N, by mass , tha t will b ecome hcn and nh3 under Partition F ractions .The fr action of v olatile N tha t will become NO will b e calcula ted b y the r emainder . •Selec t the char N c onversion pa th fr om the Char N C onversion drop-do wn list as no,hcn ,nh3 , or hcn/nh3/no . Note tha t hcn or nh3 can b e selec ted only if the same sp ecies has b een selec ted as the in- termedia te sp ecies in the N In termedia te drop-do wn list. •Specify the mass fr action of nitr ogen in the char in the Char N M ass F raction field . •Specify the o verall fr action of the char N, by mass , tha t will b e converted t o the in termedia te sp ecies and/or pr oduc t NO in the Conversion F raction field . •If you selec ted hcn/nh3/no as the char N c onversion, specify the fr action of the c onverted char N, by mass , tha t will b ecome hcn and nh3 under Partition F ractions .The fr action of char N tha t will b ecome NO will b e calcula ted b y the r emainder . •Define the BET in ternal p ore sur face area (see BET Sur face Area in the Theor y Guide f or details) of the particles in the BET S urface Area field . Imp ortant Note tha t ther e ar e limita tions tha t must b e consider ed when defining mor e than one solid fuel str eam. See Defining the F uel S treams (p.1826 ) for details . The f ollowing equa tions ar e used t o det ermine the mass fr action of nitr ogen in the v olatiles and char : (22.2) 1831Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.NOx Formationwher e = release r ate of fuel nitr ogen in k g/s = release r ate of v olatiles ( ) or char ( ) in k g/s = mass fr action of nitr ogen in v olatiles or char Let = total nitr ogen mass fr action in daf c oal (tha t is, from daf ultima te analy sis) = char nitr ogen as a fr action of t otal nitr ogen = mass fr action of v olatiles in daf c oal = mass fr action of char in daf c oal Then the f ollowing should hold: (22.3) (22.4) (22.5) (22.6) (22.7) 22.1.1.8. Setting N2O P athw ay Paramet ers The f ormation of NO thr ough an N2O in termedia te can b e pr edic ted b y an y of quasi-st eady and transp orted-simple metho ds, which c an b e sp ecified in the N2O P ath tab . •To cho ose the quasi-st eady-sta te metho d, selec t quasi-st ead y in the N2O M odel drop-do wn list. Imp ortant The tr ansp ort equa tion f or the sp ecies N2O will not b e solv ed f or N2O. However, N2O will b e up dated a t every iteration. Therefore, the r esidual v alues tha t app ear f or N2O ar e always zero. Do not b e alar med if the solv er k eeps pr inting z ero at each it eration. •To cho ose the simplified f orm of the N2O-in termedia te mechanism, selec t transp orted-simple in the N2O M odel drop-do wn list. Here, the sp ecies N2O is added t o the list of p ollutan t species , and its mass fraction is solv ed via a tr ansp ort equa tion. The a tomic O c oncentration will b e calcula ted acc ording t o the ther mal NOx[O] M odel tha t you ha ve specified pr eviously . If you ha ve not selec ted the Thermal NO x pathw ay, then y ou will b e giv en the option t o sp ecify an [O] M odel for the N2O pa thw ay calcula tion. The same thr ee options f or the ther mal NOx[O] M odel will b e the a vailable options . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1832Modeling P ollutan t FormationIf you ho oked a user-defined func tion in the Formation tab , you c an mak e a selec tion in the UDF Rate group b ox to sp ecify the tr eatmen t of the user-defined NOx rate: •Selec t Replac e Fluen t Rate to replac e the NOx rate calcula ted b y ANSY S Fluen t using N2O in termedia tes with the cust om NOx rate pr oduced b y your UDF . •Selec t Add t o Fluen t Rate to add the cust om NOx rate pr oduced b y your UDF t o the NOx rate calcula ted by ANSY S Fluen t using N2O in termedia tes. 22.1.1.9. Setting P aramet ers for NO x Reburn To enable NOx reduc tion b y rebur ning , click the Reduc tion tab in the NOx Model D ialog Box (p.3332 ) and enable the Rebur n option under Metho ds. In the e xpanded p ortion of the dialo g box, as sho wn in Figur e 22.3: The NO x Dialog Box Displa ying the R ebur n Reduc tion M etho d (p.1834 ), click the Rebur n tab under Reduc tion M etho d Paramet ers, wher e you c an cho ose fr om the f ollowing options: •To cho ose the instan taneous metho d, selec t instan taneous [CH] in the Rebur n M odel drop-do wn list. Imp ortant When y ou use this metho d, you must b e sur e to include the sp ecies CH, CH2, and CH3 in your pr oblem definition. See NOx Reduc tion b y Rebur ning in the Theor y Guide for details . •To cho ose the par tial equilibr ium metho d, selec t par tial-equilibr ium in the Rebur n M odel drop-do wn list.You then must selec t the Rebur n Fuel S pecies from the list of a vailable sp ecies . ANSY S Fluen t will allow you selec t up t o six r ebur n fuel sp ecies . Specify the Equiv alen t Fuel Type (ch4 ,ch3 ,ch2 , or ch). For e xample , if you cho ose methane as the r ebur n fuel, then the Equiv alen t Fuel Type would b e ch4 . If you cho ose a r ebur n fuel such as hv_v ol (a v olatile c omp onen t of c oal), then y ou must sp ecify the most appr opriate equiv alen t hydrocarbon fuel t ype so tha t the par tial equilibr ium mo del will b e set up c orrectly. •Due t o coal v olatiles b ehaving v ery diff erently, it is imp ortant to selec t the c orrect equiv alen t fuel t ype. You must first c onsider the v olatile fuel c omp osition, then check the C/H r atio t o find the fuel tha t most closely ma tches CH, CH2, CH3, or CH4[68] (p.4008 ).While the metho d for b est det ermining the equiv alen t fuel is deba table , consider ing the C/H r atio of the fuel itself is a r easonable indic ator. 1833Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.NOx FormationFigur e 22.3: The NO x Dialo g Box Displa ying the Rebur n Reduc tion M etho d 22.1.1.10. Setting SNCR P aramet ers Prior t o enabling r educ tion b y SNCR, mak e sur e tha t you ha ve included in the sp ecies list nh3 (for reduc tion b y ammonia injec tion) and co2 (for reduc tion b y ur ea injec tion). See NOx Reduc tion by SNCR in the Theor y Guide for detailed inf ormation ab out SNCR theor y. 1.To enable NOx reduc tion b y SNCR, click the Reduc tion tab in the NOx Model D ialog Box (p.3332 ) and enable the SNCR option under Metho ds, as sho wn in Figur e 22.4: The NO x Dialog Box Displa ying the SNCR Reduc tion M etho d (p.1834 ). Figur e 22.4: The NO x Dialo g Box Displa ying the SNCR Reduc tion M etho d 2.In the SNCR tab under Reduc tion M etho d Paramet ers,set fr om the f ollowing options: •To ha ve ammonia or ur ea included as a gas-phase p ollutan t species fr om the injec tion lo cations , selec t gaseous in the Injec tion M etho d drop-do wn list. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1834Modeling P ollutan t FormationIf you plan t o selec t this option f or NOx postpr ocessing , then y ou must also include ammonia or ur ea as a gas-phase sp ecies . Additionally , you must sp ecify the mass fr action of ammonia or urea a t the r espective inlet f or the SNCR injec tion. You must include this set of inputs pr ior t o the main ANSY S Fluen t combustion c alcula tion. •To ha ve ammonia included as a liquid-phase p ollutan t species fr om the injec tion lo cations , selec t liquid in the Injec tion M etho d drop-do wn list. If urea is injec ted as a liquid solution, then selec t liquid in the Injec tion M etho d drop-do wn list. Note tha t you must enable the DPM mo del with ur ea or ammonia included as a ma terial. Note All par ticle t ypes such as dr oplets , combusting , and multic omp onen t par ticles ar e compa tible with the SNCR mo del. If you plan t o selec t this option f or NOx postpr ocessing , then y ou must include NH3 as b oth a gas-phase and liquid-phase sp ecies . Additionally , you must sp ecify injec tion lo cations f or liquid droplet ammonia par ticles and set gaseous ammonia as the e vaporation sp ecies .You must in- clude this set of inputs in c onjunc tion with the main ANSY S Fluen t combustion c alcula tion. Since ur ea is a subliming solid , and usually is injec ted as a solution, mix ed in w ater, you ha ve to define solid pr operties f or ur ea under the Create/Edit M aterials D ialog Box (p.3386 ). It is assumed that the w ater e vaporates b efore ur ea b egins its subliming pr ocess.The sublima tion pr ocess is modeled similar t o the single r ate de volatiliza tion mo del of c oal. You will supply the v alue f or the sublima tion r ate (s-1).You must sp ecify the w ater content while defining the injec tion properties. •Specify the SNCR Reagen t Species as nh3 (ammonia) or co2 (urea) in the dr op-do wn list. •When using the non-pr emix ed c ombustion mo del with a liquid-phase r eagen t injec tion, enter a v alue in the Reagen t Fraction in S tream to sp ecify the mass fr action of the r eagen t in the r eagen t str eam. The r emaining mass fr action is assumed t o be water. If you enabled a sec ondar y str eam in y our PDF calcula tion, by default the sec ondar y str eam will ac t as the r eagen t str eam. You c an assign the pr imar y stream as the r eagen t str eam b y using the t ext command tha t follows (en ter 0 in r esponse t o the PDF Stream ID prompt tha t follows the Injection Method prompt): define/models/nox-parameters/nox-chemistry •If the Reagen t Species selec ted is co 2 , then y ou will either acc ept the rate-limiting option for Urea D ecomp osition , or sp ecify the NH3 C onversion value when selec ting a user-sp ecified Urea Decomp osition . You will use the ur ea dec omp osition under the SNCR tab t o define which of the t wo dec om- position mo dels is t o be used .The first mo del (which is the default) is the r ate-limiting dec om- position mo del, as giv en in Table 14.3: Two-Step U rea B reakdo wn P rocess in the Theor y Guide . ANSY S Fluen t will then c alcula te the sour ce terms acc ording t o the r ates giv en in Table 14.3: Two- Step U rea B reakdo wn P rocess in the Theor y Guide .The sec ond mo del is f or when y ou assume that the ur ea dec omp oses instan tly in to ammonia and HNC O at a giv en pr oportion. In this c ase, you will sp ecify the molar c onversion fr action f or ammonia, assuming tha t the r est of the ur ea is converted t o HNC O. An example v alue is giv en ab ove. 1835Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.NOx FormationThe v alue f or user-sp ecified NH3 conversion is the mole fr action of NH3 in the mix ture of NH3 and HNC O tha t is instan tly cr eated fr om the r eagen t injec tion. In this c ase, ther e is no ur ea sour ce because all of r eagen t is assumed t o convert to both NH3 and HNC O, instan tly. 22.1.1.11. Setting Turbulenc e Paramet ers If you w ant to tak e in to acc oun t turbulen t fluc tuations (as descr ibed in NOx Formation in Turbulen t Flows in the Theor y Guide ) when y ou c omput e the sp ecified NOx formation (ther mal, prompt , and/or fuel, with or without r ebur n), define the turbulenc e par amet ers in the Turbulenc e In teraction M ode tab. Figur e 22.5: The NO x M odel D ialo g Box and the Turbulenc e In teraction M ode Tab Selec t one of the options in the PDF M ode drop-do wn list in the Turbulenc e In teraction M ode tab: •Selec t temp erature to tak e into acc oun t fluc tuations of t emp erature. •Selec t temp erature/sp ecies to tak e into acc oun t fluc tuations of t emp erature and mass fr action of the species selec ted in the Species drop-do wn list (which app ears when y ou selec t this option). •(non-pr emix ed and par tially pr emix ed c ombustion c alcula tions only) S elec t mix ture fraction to tak e into accoun t fluc tuation in the mix ture fraction(s). Imp ortant When mo deling the f ormation of other p ollutan ts along with NOx, you should c ompar e the selec tions made in the PDF M ode drop-do wn lists in the Turbulenc e In teraction Mode group b oxes of the NOx Model D ialog Box (p.3332 ) and the Turbulenc e In teraction Mode group b oxes of the SOx M odel and Soot M odel dialo g boxes. If mix ture fr action Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1836Modeling P ollutan t Formationis selec ted in an y of these dialo g boxes, then it must b e selec ted in all of the others as well. The mix ture fr action option is a vailable only if y ou ar e using either the non-pr emix ed or par tially premix ed c ombustion mo del t o mo del the r eacting sy stem. If you use the mix ture fr action option, the instan taneous t emp eratures and sp ecies c oncentrations ar e tak en fr om the PDF lo ok-up table as a func tion of mix ture fraction and en thalp y and the instan taneous NOx rates ar e calcula ted a t each cell.The PDF used f or c onvoluting the instan taneous NOx rates is the same as the one used t o comput e the mean flo w-field pr operties. For e xample , for single-mix ture fraction mo dels the b eta PDF is used , and f or two-mix ture fraction mo dels , the b eta or the double delta PDF c an b e used .The PDF f or mixture fraction is c alcula ted fr om the v alues of mean mix ture fraction and v arianc e at each c ell, and the instan taneous NOx rates ar e convolut ed with the mix ture fraction PDF t o yield the mean r ates in turbulen t flo w. Note When mixture fraction is selec ted as PDF mo de, ANSY S Fluen t calcula tes and tabu- lates the NOx rates apr iori for fast er computa tions of NOx rates.The NOx rates ar e tabula ted at the first NOx iteration and a message Performing Pollutant PDF integrations... is displa yed in the F luen t console . If you selec ted temp erature or temp erature/sp ecies for the PDF M ode, you should define the f ol- lowing par amet ers in the Turbulenc e In teraction M ode tab: PDF Type allows you t o sp ecify the shap e of the PDF , which is then in tegrated t o obtain mean r ates for the t em- perature and (if y ou selec ted temp erature/sp ecies for the PDF M ode) the sp ecies . If you selec t beta, the PDF will b e mo deled using Equa tion 14.108 in the Theor y Guide . If you selec t gaussian , the PDF will be mo deled using Equa tion 14.111 in the Theor y Guide . PDF P oints allows you t o sp ecify the numb er of p oints used t o integrate the b eta or G aussian func tion in Equa- tion 14.105 or Equa tion 14.106 in the Theor y Guide on a hist ogram basis .The default v alue of 10 is a minimum v alue . It is r ecommended tha t you r un the c alcula tion with this minimum v alue t o convergenc e, and then k eep incr easing the v alue (f or e xample , 20–25) un til the p ollutan ts of in terest st op changing . Increasing this v alue ma y impr ove accur acy, but will also incr ease the c omputa tion time . Temp erature Varianc e allows you t o sp ecify the f orm of tr ansp ort equa tion tha t is solv ed t o calcula te the t emp erature varianc e. The default selec tion is algebr aic, which is an appr oxima te form of the tr ansp ort equa tion (see Equa- tion 14.114 of the Theor y Guide ).You also ha ve the option of selec ting transp orted to solv e Equa- tion 14.113 in the Theor y Guide .Though the transp orted form is mor e exact, it is mor e expensiv e computa tionally . Tmax Option provides v arious options f or det ermining the maximum limit of the t emp erature used f or the in tegration of the PDF (see Equa tion 8.44 in the Fluent Theor y Guide ) to calcula te mean r ates for turbulen t fluc tuations of NOx: 1837Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.NOx Formation•The default selec tion is global-tmax , which sets the limit as the maximum t emp erature in the flo w field . •You c an selec t local-tmax if you w ould r ather obtain c ell-based maximum t emp erature limits b y multiplying the lo cal cell mean t emp erature by the v alue en tered in Tmax F actor. •You c an selec t specified-tmax to set the limit f or each c ell to be the v alue en tered in Tmax . •If you ha ve selec ted a user-defined func tion in the NOx Rate drop-do wn list in the Formation tab , then y ou c an selec t user-defined so tha t the t emp erature limit is sp ecified b y a user-defined func tion. See the Fluen t Customiza tion M anual for details ab out user-defined func tions . Species only app ears if y ou ha ve selec ted temp erature/sp ecies for the PDF M ode.Your selec tion in this dr op- down menu det ermines which sp ecies ’ mass fr action is included in the NOx formation c alcula tions . Imp ortant Note tha t the sp ecies v arianc e will alw ays be calcula ted using the algebr aic f orm of the transp ort equa tion ( Equa tion 14.114 in the Theor y Guide ). 22.1.1.12. Defining B oundar y Conditions for the NO x Mo del At flo w inlet b oundar ies, you must sp ecify the Pollutan t NO M ass F raction , and if nec essar y, the Pollutan t HCN M ass F raction ,Pollutan t NH3 M ass F raction , and Pollutan t N2O M ass F raction . Setup → Boundar y Conditions You c an r etain the default inlet v alues of z ero for these quan tities or y ou c an en ter nonz ero numb ers as appr opriate for y our c ombustion sy stem. 22.1.2. Solution S trategies To solv e for NOx produc ts, perform the f ollowing st eps: 1.(optional) I f the discr ete phase mo del (DPM) is tur ned on (b y enabling the Interaction with C ontinuous Phase ) to run with the NOx mo del, then set the DPM I teration In terval to 0 such tha t no DPM it erations are performed as the NOx case is b eing solv ed. 2.In the Equa tions D ialog Box (p.3609 ) of the Solution C ontrols Task P age (p.3606 ), turn off the solution of all variables e xcept sp ecies NO (and HCN, NH3, or N2O, based on the mo del selec ted). 3. Solution → Controls → Equa tions ... 4.In the Solution C ontrols task page , set a suitable v alue f or the NO (and HCN, NH3, or N2O, if appr opriate) under-r elaxa tion. A value of 1.0 is suggest ed, although lo wer values ma y be requir ed f or certain pr oblems (tha t is, if convergenc e cannot b e obtained , try a lo wer under-r elaxa tion v alue). 5.In the Residual M onit ors D ialog Box (p.3910 ), decr ease the c onvergenc e criterion f or NO (and HCN, NH3, or N2O, if appr opriate) to 10-6. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1838Modeling P ollutan t FormationSolution → Monit ors → Residuals Edit... 6.Perform calcula tions un til convergenc e (tha t is, until the NO—and HCN, NH3, or N2O, if solv ed—sp ecies residuals ar e below 10-6) to ensur e tha t the NO and HCN or NH3 concentration fields ar e no longer e volving . Solution → Run C alcula tion 22.1.3. Postpr ocessing When y ou c omput e NOx formation, the f ollowing additional v ariables will b e available f or p ostpr ocessing: •Mass fr action of P ollutan t no •Mass fr action of P ollutan t hcn (appr opriate fuel NOx mo del only) •Mass fr action of P ollutan t nh3 (appr opriate fuel NOx mo del only) •Mass fr action of P ollutan t n2o (N2O-in termedia te mo del only) •Mass fr action of P ollutan t ur ea (SNCR ur ea injec tion) •Mass fr action of P ollutan t hnc o (SNCR ur ea injec tion) •Mass fr action of P ollutan t nc o (SNCR ur ea injec tion) •Mole fr action of P ollutan t no •Mole fr action of P ollutan t hcn (appr opriate fuel NOx mo del only) •Mole fr action of P ollutan t nh3 (appr opriate fuel NOx mo del only) •Mole fr action of P ollutan t n2o (N2O-in termedia te mo del only) •Mole fr action of P ollutan t ur ea (SNCR ur ea injec tion) •Mole fr action of P ollutan t hnc o (SNCR ur ea injec tion) •Mole fr action of P ollutan t nc o (SNCR ur ea injec tion) •no D ensit y •hcn D ensit y (appr opriate fuel NOx mo del only) •nh3 D ensit y (appr opriate fuel NOx mo del only) •n2o D ensit y (N2O-in termedia te mo del only) •urea D ensit y (SNCR ur ea injec tion) •hnc o D ensit y (SNCR ur ea injec tion) •nco D ensit y (SNCR ur ea injec tion) 1839Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.NOx Formation•Rate of no (from the individual pa thw ays) •Rate of hcn (appr opriate fuel NOx mo del only) •Rate of nh3 (appr opriate fuel NOx mo del only) •Rate of n2o (N2O-in termedia te mo del only) •Rate of ur ea (SNCR ur ea injec tion) •Rate of hnc o (SNCR ur ea injec tion) •Rate of nc o (SNCR ur ea injec tion) These v ariables ar e contained in the NOx... categor y of the v ariable selec tion dr op-do wn list tha t app ears in p ostpr ocessing dialo g boxes. Additional NO r ates fr om individual pa thw ays,Thermal ,Prompt ,Fuel, N2O P ath, and SNCR can b e plott ed. 22.2. SOx Formation The f ollowing sec tions descr ibe ho w to use the SOx mo del in ANSY S Fluen t. For inf ormation ab out the theor y behind the SOx mo dels in ANSY S Fluen t, see SOx Formation in the Theor y Guide . 22.2.1. Using the SO x Model 22.2.2. Solution S trategies 22.2.3. Postpr ocessing 22.2.1. Using the SO x M odel When the sulfur c ontent in the fuel is lo w, SOx concentrations tha t are gener ated in c ombustion gen- erally ha ve minimal influenc e on the pr edic ted flo w field , temp erature, and major c ombustion pr oduc t concentrations .The most efficien t way to use the SOx mo del is as a p ostpr ocessor t o the main c om- bustion c alcula tion. However, if the sulfur c ontent is high, then SOx formation should b e coupled with the gas phase c ombustion pr ocess r ather than tr eating it as a p ostpr ocessing st ep. The pr ocedur e for enabling and setting up the mo del f or a dec oupled solution is as f ollows: 1.Calcula te your c ombustion pr oblem using ANSY S Fluen t. Imp ortant The pr emix ed c ombustion mo del and the F lamelet gener ated manif old mo del ar e not compa tible with the SOx mo del. 2.Enable the SOx mo del, define the fuel str eams , and set the appr opriate par amet ers, as descr ibed in this section. Setup → Models → Species → SOx Edit... 3.Define the b oundar y conditions f or SO2 and H2S (and SO3, SH, or SO if nec essar y) at flo w inlets . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1840Modeling P ollutan t FormationSetup → Boundar y Conditions 4.In the Equa tions D ialog Box (p.3609 ), turn off the solution of all v ariables e xcept sp ecies SO2 and H2S (and SO3, SH, or SO , based on y our selec tions). Solution → Controls → Equa tions ... 5.Perform calcula tions un til convergenc e (tha t is, until the SO2 and H2S—and SO3, SH, or SO , if solv ed—sp ecies r esiduals ar e below 10-6) to ensur e tha t the SO2 and H2S concentration fields ar e no longer e volving . Solution → Run C alcula tion 6.Review the mass fr actions of SO2 and H2S (and SO3, SH, or SO) b y gener ating gr aphic al plots or alphanu- mer ic reports in the usual w ay. 7.Save a new set of c ase and da ta files , if desir ed. File → Write → Case & D ata... 22.2.1.1. Enabling the SO x Mo del To mo del SOx formation, enable the SOx Formation option in the SOx Model D ialog Box (p.3339 ) (Figur e 22.6: The SO x Model D ialog Box (p.1842 )). Setup → Models → Species → SOx Edit... 1841Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.SOx FormationFigur e 22.6: The SO x M odel D ialo g Box 22.2.1.2. Defining the F uel Str eams When mo deling fuel SOx formation, ANSY S Fluen t allo ws you t o define up t o thr ee separ ate fuel streams , and t o selec t the fuel sour ces for each fuel str eam. You c an define multiple fuel str eams t o include in y our mo del with the f ollowing c onfigur ations: •Solid and liquid fuels (c ombusting par ticle and dr oplet) b oth c ontributing t o fuel SOx. •Two or thr ee solid fuels with diff erent -content and SO2 /H2S pr oduc tion mo dels (t wo or thr ee combusting par ticles), for e xample c oal blends , coal-biomass c ofiring, and so on. •Two or thr ee liquid fuels with diff erent -content and SO2 /H2S pr oduc tion mo dels (t wo or thr ee droplet or multic omp onen t par ticles). •Gas and solid (or dr oplet) fuel b oth c ontributing t o fuel SOx. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1842Modeling P ollutan t FormationIn addition, you c an mo del one solid fuel c ontributing t o SOx in the pr esenc e of another r eacting solid par ticle not c ontaining an y , by sp ecifying the ac tive fuel sour ce for SOx formation. For this c onfigur ation, you will not need t o define multiple fuel str eams in y our mo del. You c an define multiple fuel str eams when y ou ar e mo deling SOx formation, as sho wn in the f ollowing steps: 1.Specify the Numb er of F uel S treams in the Fuel S treams group b ox.You ar e allo wed up t o thr ee sep- arate fuel str eams . 2.Define the first fuel str eam. a.Selec t the fuel str eam t o be defined b y using the ar row keys of the Fuel S tream ID field . b.Selec t the Fuel Type in the Fuel S tream S ettings group b ox. c.If your Fuel Type is Liquid or Solid , selec t the S sour ces fr om the Fuel S our ces list. •If the Fuel Type is Solid and y ou ha ve defined multiple injec tions with diff erent combusting par ticle materials in y our r eacting flo w calcula tion, the a vailable c ombusting par ticle ma terials will b e list ed in the Fuel S our ces list. Selec t one or mor e ma terials fr om the list t o be included as fuel sour ces in the SOx calcula tion. Your selec tion will b e used t o det ermine the char bur nout r ate and volatile r elease r ate in Equa tion 14.124 and Equa tion 14.125 in the Theor y Guide . Make sur e to deselec t all c ombusting par ticle ma terials tha t do not c ontribut e to SOx. •If the Fuel Type is Liquid and y ou ha ve defined multiple injec tions with diff erent droplet or mul- ticomp onen t par ticle ma terials in y our r eacting flo w calcula tion, the a vailable ma terials will b e listed in the Fuel S our ces list. Selec t one or mor e ma terials fr om the list t o be included as fuel sour ces in the SOx calcula tion. Your selec tion will b e used t o det ermine the fuel r elease r ate in Equa tion 14.123 in the Theor y Guide . Make sur e to deselec t all dr oplet and multic omp onen t materials tha t do not c ontribut e to SOx. d.If the Fuel Type in y our mo del is Gas, selec t one or mor e ma terials fr om the Fuel S pecies list. You cannot selec t mor e than 5 fuel sp ecies f or each fuel str eam, and the t otal numb er of fuel sp ecies se- lected f or all the fuel str eams c ombined c annot e xceed 10. Your selec tion will b e used t o det ermine the mean limiting r eaction r ate in Equa tion 14.122 in the Theor y Guide . e.Specify the par amet ers f or this par ticular fuel str eam in the Fuel S tream S ettings group b ox. See Defining the SO x Fuel S tream S ettings (p.1844 ) for details . 3.Repeat steps 2.(a)–2.(e) f or each additional fuel str eam. Imp ortant Imp ortant consider ations should b e made when r eading c ase and da ta files set up in a version of ANSY S Fluen t 14.5 or ear lier: •When r eading a c ase and da ta file with multiple injec tion ma terials tha t was set up in a v ersion of ANSY S Fluen t previous t o and including 14.5, ANSY S Fluen t will initializ e the injec tion ma- terial sp ecific fuel sour ces for the fuel SOx mo del. ANSY S Fluen t will p erform a DPM it eration when the flo w iterations ar e initia ted. 1843Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.SOx Formation•When r eading a c ase file tha t was set up in a v ersion older than ANSY S Fluen t 14.5 with multiple fuel str eams defined f or the SOx mo del, you must r eview the setup and selec t the S sour ces from the Fuel S our ces list. 22.2.1.3. Defining the SO x Fuel Str eam S ettings When using the SOx mo del, you must set the par amet ers in the Fuel S tream S ettings group b ox for each fuel str eam sp ecified in the Fuel S tream ID field . To begin, specify the fuel t ype in the f ollowing manner : •To calcula te SOx formation fr om a solid fuel, selec t Solid under Fuel Type. •To calcula te SOx formation fr om a liquid fuel, selec t Liquid under Fuel Type. •To calcula te SOx formation fr om a gaseous fuel, selec t Gas under Fuel Type. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1844Modeling P ollutan t FormationFigur e 22.7: The SO x M odel D ialo g Box Displa ying Liquid F uel P aramet ers Note tha t you c an use only one of the fuel t ypes for a giv en fuel str eam. The Gas option is a vailable only when the Species Transp ort mo del is enabled (see Enabling S pecies Transp ort and R eactions and C hoosing the M ixture M aterial (p.1616 )). 22.2.1.3.1. Setting SO x Paramet ers for G aseous and Liquid F uel Types If you ha ve selec ted Gas or Liquid as the Fuel Type, you must sp ecify the f ollowing: •Selec t the in termedia te sp ecies ( h2s ,so2, or h2s/so2 ) in the S In termedia te drop-do wn list. •Set the c orrect mass fr action of sulfur in the fuel (k g sulfur p er kg fuel) in the Fuel S M ass F raction field . •Specify the o verall fr action of the fuel , by mass , tha t will b e converted t o the in termedia te sp ecies and/or pr oduc t SO2 in the Conversion F raction field .Therefore, any remaining will not c ontribut e to SOx formation. This is based on the assumption tha t the r emaining v olatile will c onvert to gas phase sulfur .The Conversion F raction for the S In termedia te has a default v alue of 1. 1845Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.SOx Formation•If you selec ted h2s/so2 as the in termedia te, you must set the fr action of the c onverted fuel , by mass , that will b ecome h2s under Partition F ractions .The fr action of fuel tha t will b ecome SO2 will b e cal- cula ted b y the r emainder . Note tha t setting a par tition fr action of 0 f or H2S is equiv alen t to assuming tha t all fuel S is c on- verted t o the final pr oduc t SO2. 22.2.1.3.2. Setting SO x Paramet ers for a S olid F uel For solid fuel, several inputs ar e requir ed f or the SOx mo del. Figur e 22.8: The SO x M odel D ialo g Box Displa ying S olid F uel P aramet ers •Selec t the in termedia te sp ecies ( h2s ,so2, or h2s/so2 ) in the S In termedia te drop-do wn list. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1846Modeling P ollutan t Formation•Specify the mass fr action of sulfur in the v olatiles in the Volatile S M ass F raction field . •Specify the o verall fr action of the v olatile , by mass , tha t will b e converted t o the in termedia te sp ecies and/or pr oduc t SO2 in the Conversion F raction field . •If you selec ted h2s/so2 as the v olatile intermedia te, you must sp ecify the fr action of the c onverted volatile , by mass , tha t will b ecome h2s under Partition F ractions .The fr action of v olatile tha t will become SO2 will b e calcula ted b y the r emainder . •Selec t the char conversion pa th fr om the Char S C onversion drop-do wn list as so2,h2s , or so2/h2s . •Specify the mass fr action of sulfur in the char in the Char S M ass F raction field . •Specify the o verall fr action of the char , by mass , tha t will b e converted t o the in termedia te sp ecies and/or pr oduc t SO2 in the Conversion F raction field . •If you selec ted so2/h2s from the Char S C onversion drop-do wn list , you must sp ecify the fr action of the c onverted char , by mass , tha t will b ecome SO2 under Partition F ractions .The fr action of char that will b ecome H2S will b e calcula ted b y the r emainder . The f ollowing equa tions ar e used t o det ermine the mass fr action of sulfur in the v olatiles and char : (22.8) wher e = release r ate of fuel sulfur in k g/s = release r ate of v olatiles (v) or char (c) in k g/s = mass fr action of sulfur in v olatiles or char Let = total sulfur mass fr action in daf c oal (tha t is, from daf ultima te analy sis) = char sulfur as a fr action of t otal sulfur = mass fr action of v olatiles in daf c oal = mass fr action of char in daf c oal Then the f ollowing should hold: (22.9) (22.10) (22.11) (22.12) (22.13) 1847Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.SOx Formation22.2.1.4. Defining the SO x Formation Mo del P aramet ers You c an set the SOx formation mo del par amet ers tha t apply t o all of the fuel str eams in the Formation Model P aramet ers group b ox: •You ha ve the option of including SO3 as a pr oduc t, and including SH and SO as in termedia tes b y enabling the Include SO3 P roduc t and the Include SH and SO In termedia tes options , respectively. See Reaction Mechanisms f or Sulfur O xida tion in the Theor y Guide for fur ther inf ormation. •Specify the metho d by which O and OH will b e calcula ted.The SOx routines emplo y thr ee metho ds for reduc tion c alcula tions of SOx: –You c an selec t equilibr ium ,par tial-equilibr ium , or instan taneous in the [O] M odel drop-do wn list. –You c an selec t none ,par tial-equilibr ium , or instan taneous in the [OH] M odel drop-do wn list. Imp ortant To use the pr edic ted O and/or OH c oncentration, selec t instan taneous in the [O] Model or [OH] M odel drop-do wn list. 22.2.1.5. Setting Turbulenc e Paramet ers If you w ant to tak e in to acc oun t turbulen t fluc tuations when y ou c omput e the sp ecified SO2 formation, define the turbulenc e par amet ers in the Turbulenc e In teraction M ode group b ox. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1848Modeling P ollutan t FormationFigur e 22.9: The SO x M odel D ialo g Box for a G as F uel Type with Turbulenc e Selec t one of the options in the PDF M ode drop-do wn list: •Selec t temp erature to tak e into acc oun t fluc tuations of t emp erature. •Selec t temp erature/sp ecies to tak e into acc oun t fluc tuations of t emp erature and mass fr action of the species selec ted in the Species drop-do wn list (which app ears when y ou selec t this option). 1849Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.SOx Formation•(non-pr emix ed and par tially pr emix ed c ombustion c alcula tions only) S elec t mix ture fraction to tak e into accoun t fluc tuation in the mix ture fraction(s). Imp ortant When mo deling the f ormation of other p ollutan ts along with SOx, you should c ompar e the selec tions made in the PDF M ode drop-do wn lists in the Turbulenc e In teraction Mode tab of the NOx Model D ialog Box (p.3332 ) and the Turbulenc e In teraction M ode group b oxes of the SOx M odel and Soot M odel dialo g boxes. If mix ture fr action is selec ted in an y of these dialo g boxes, then it must b e selec ted in all of the others as w ell. The mix ture fr action option is a vailable only if y ou ar e using either the non-pr emix ed or par tially premix ed c ombustion mo del t o mo del the r eacting sy stem. If you use the mix ture fr action option, the instan taneous t emp eratures and sp ecies c oncentrations ar e tak en fr om the PDF lo ok-up table as a func tion of mix ture fraction and en thalp y and the instan taneous SOx rates ar e calcula ted a t each cell.The PDF used f or c onvoluting the instan taneous SOx rates is the same as the one used t o comput e the mean flo w-field pr operties. For e xample , for single-mix ture fraction mo dels the b eta PDF is used , and f or two-mix ture fraction mo dels , the b eta or the double delta PDF c an b e used .The PDF f or mixture fraction is c alcula ted fr om the v alues of mean mix ture fraction and v arianc e at each c ell, and the instan taneous SOx rates ar e convolut ed with the mix ture fraction PDF t o yield the mean r ates in turbulen t flo w. If you selec ted temp erature or temp erature/sp ecies for the PDF M ode, you should define the f ol- lowing par amet ers in the Turbulenc e In teraction M ode group b ox: PDF Type allows you t o sp ecify the shap e of the PDF , which is then in tegrated t o obtain mean r ates for the t em- perature and (if y ou selec ted temp erature/sp ecies for the PDF M ode) the sp ecies . If you selec t beta, the PDF will b e mo deled using Equa tion 14.108 in the Theor y Guide . If you selec t gaussian , the PDF will be mo deled using Equa tion 14.111 in the Theor y Guide . PDF P oints allows you t o sp ecify the numb er of p oints used t o integrate the b eta or G aussian func tion in Equa- tion 14.105 or Equa tion 14.106 in the Theor y Guide on a hist ogram basis .The default v alue of 10 is a minimum v alue . It is r ecommended tha t you r un the c alcula tion with this minimum v alue t o convergenc e, and then k eep incr easing the v alue (f or e xample , 20–25) un til the p ollutan ts of in terest st op changing . Increasing this v alue ma y impr ove accur acy, but will also incr ease the c omputa tion time . Temp erature Varianc e allows you t o sp ecify the f orm of tr ansp ort equa tion tha t is solv ed t o calcula te the t emp erature varianc e. The default selec tion is algebr aic, which is an appr oxima te form of the tr ansp ort equa tion (see Equa- tion 14.114 in the Theor y Guide ).You ha ve the option of selec ting transp orted to inst ead solv e Equa- tion 14.113 in the Theor y Guide .Though the transp orted form is mor e exact, it is also mor e expensiv e computa tionally . Tmax Option provides v arious options f or det ermining the maximum limit of the t emp erature used f or the in tegration of the PDF (see Equa tion 8.44 in the Fluent Theor y Guide ) to calcula te mean r ates for turbulen t fluc tuations of SOx: •The default selec tion is global-tmax , which sets the limit as the maximum t emp erature in the flo w field . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1850Modeling P ollutan t Formation•You c an selec t local-tmax if you w ould r ather obtain c ell-based maximum t emp erature limits b y multiplying the lo cal cell mean t emp erature by the v alue en tered in Tmax F actor. •You c an selec t specified-tmax to set the limit f or each c ell to be the v alue en tered in Tmax . •If you ha ve selec ted a user-defined func tion fr om the SOx Rate drop-do wn menu in the User-D efined Func tions group b ox, then y ou c an selec t user-defined so tha t the limit is sp ecified b y a user-defined func tion. See the Fluen t Customiza tion M anual for details ab out user-defined func tions . Species only app ears if y ou ha ve selec ted temp erature/sp ecies for the PDF M ode.Your selec tion in this dr op- down menu det ermines which sp ecies ’ mass fr action is included in the SOx formation c alcula tions . Imp ortant Note tha t the sp ecies v arianc e will alw ays be calcula ted using the algebr aic f orm of the transp ort equa tion ( Equa tion 14.114 in the Theor y Guide ). 22.2.1.6. Specifying a User -Defined F unc tion for the SO x Rate You c an cho ose t o sp ecify a user-defined func tion f or the r ate of SOx produc tion. By default , the r ate retur ned fr om the user-defined func tion is added t o the r ate retur ned fr om the standar d SOx produc tion options .You also ha ve the option of r eplacing ANSY S Fluen t’s SOx rate calcula tions with y our o wn user-defined SOx rate. In addition t o or inst ead of using the UDF t o sp ecify the SOx rate, you c an use it t o sp ecify cust om values f or the maximum limit ( ) tha t is used f or the in tegration of the t emp erature PDF (when temp erature is acc oun ted f or in the turbulenc e in teraction mo deling). To use a UDF t o add a r ate to ANSY S Fluen t’s SOx rate calcula tions , you must c ompile and load the desir ed func tion, and then selec t it fr om the SOx Rate drop-do wn list in the User-D efined F unc tions group b ox. After y ou ha ve selec ted the UDF , you ha ve the f ollowing options: •You c an sp ecify tha t your cust om r ate is added t o the ANSY S Fluen t SOx rate calcula tions , by retaining the default selec tion of Add t o the F luen t Rate in the UDF R ate group b ox. •You c an r eplac e the ANSY S Fluen t SOx rate calcula tions with y our cust om r ate, by selec ting Replac e Fluen t Rate in the UDF R ate group b ox. •You c an sp ecify cust om v alues f or , by selec ting user-defined from the Tmax Option drop-do wn list in the Turbulenc e In teraction M ode group b ox. See the Fluen t Customiza tion M anual for details ab out user-defined func tions . 22.2.1.7. Defining B oundar y Conditions for the SO x Mo del At flo w inlet b oundar ies, you must sp ecify the Pollutan t SO M ass F raction , and if nec essar y, the Pollutan t SH M ass F raction ,Pollutan t H2S M ass F raction ,Pollutan t SO3 M ass F raction , and Pol- lutan t SO2 M ass F raction in the Species tab , as demonstr ated in Figur e 22.10: The M ass-F low Inlet Dialog Box: the Species Tab (p.1852 ). 1851Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.SOx FormationSetup → Boundar y Conditions You c an r etain the default inlet v alues of z ero for these quan tities or y ou c an en ter nonz ero numb ers as appr opriate for y our c ombustion sy stem. Figur e 22.10: The M ass-F low Inlet D ialo g Box: the Species Tab 22.2.2. Solution S trategies To solv e for SOx produc ts: •(optional) I f the discr ete phase mo del (DPM) is tur ned on (b y enabling the Interaction with C ontinuous Phase ) to run with the SOx mo del, then set the DPM I teration In terval to 0 such tha t no DPM it erations are performed as the SOx case is b eing solv ed. •In the Equa tions D ialog Box (p.3609 ) of the Solution C ontrols Task P age (p.3606 ), turn off the solution of all variables e xcept Pollutan t so2 and Pollutan th2s (and Pollutan t so3 ,Pollutan t sh , and Pollutan t so , if applic able). Solution → Controls → Equa tions ... •In the Solution C ontrols Task P age (p.3606 ), set suitable v alues f or the p ollutan t SO2 and H2S (and SO3, SH, and SO , if applic able) under-r elaxa tion fac tors. A value of 1.0 is suggest ed, although lo wer values ma y be requir ed f or certain pr oblems .That is, if convergenc e cannot b e obtained , try a lo wer under-r elaxa tion value . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1852Modeling P ollutan t FormationSolution → Controls •Under Spatial D iscr etiza tion in the Solution M etho ds Task P age (p.3603 ), selec t the desir ed scheme f or each of the p ollutan ts, SO2 and H2S (and SO3, SH, and SO , if applic able) Solution → Metho ds •In the Residual M onit ors D ialog Box (p.3910 ), decr ease the c onvergenc e criterion f or the p ollutan ts SO2 and H2S (and SO3, SH, and SO , if applic able) t o 10-6. Solution → Monit ors → Residuals Edit... •Perform calcula tions un til convergenc e (tha t is, until the SO2 and H2S—and SO3, SH, and SO—p ollutan t residuals ar e below 10-6) to ensur e tha t SO2 and H2S (and SO3, SH, and SO) c oncentration fields ar e no longer e volving . Solution → Run C alcula tion •Review the mass fr actions of p ollutan ts, SO2 and H2S (and SO3, SH, and SO), by gener ating gr aphic al plots or alphanumer ic reports as descr ibed in Postpr ocessing (p.1853 ). 22.2.3. Postpr ocessing When y ou c omput e SOx formation, the f ollowing additional v ariables will b e available f or p ostpr ocessing . They are contained in the SOx... categor y of the v ariable selec tion dr op-do wn list tha t app ears in postpr ocessing dialo g boxes. •Mass fr action of p ollutan t so2 •Mass fr action of p ollutan t h2s •Mass fr action of p ollutan t so3 •Mass fr action of p ollutan t sh •Mass fr action of p ollutan t so •Mole fr action of p ollutan t so2 •Mole fr action of p ollutan t h2s •Mole fr action of p ollutan t so3 •Mole fr action of p ollutan t sh •Mole fr action of p ollutan t so •so2 D ensit y •h2s D ensit y 1853Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.SOx Formation•so3 D ensit y •sh D ensit y •so D ensit y •Rate of so2 •Rate of h2s •Rate of so3 •Rate of sh •Rate of so 22.3. Soot F ormation This sec tion c ontains inf ormation ab out using the so ot formation mo dels in ANSY S Fluen t. For inf orm- ation ab out the theor y behind the so ot mo dels in ANSY S Fluen t, see Soot F ormation in the Theor y Guide . 22.3.1. Using the S oot M odels 22.3.1. Using the S oot M odels When the mass fr action of so ot is r elatively lar ge (f or e xample , 10%) or if y our pr oblem in volves the effect of r adia tion, the so ot formation should b e comput ed as par t of the main c ombustion solution and not thr ough p ostpr ocessing (as is done f or the NOx and SOx mo dels). The pr ocedur e for setting up and solving a so ot formation mo del is outlined b elow. Only the st eps tha t are pertinen t to so ot modeling ar e sho wn her e. For inf ormation ab out inputs r elated t o other mo dels tha t you ar e using in conjunc tion with the so ot formation mo del, see the appr opriate sec tions f or those mo dels . 1.Set up y our c ombustion pr oblem using ANSY S Fluen t as usual. Note the f ollowing limita tions: •None of the so ot mo dels ar e compa tible with pr emix ed c ombustion. •The one-st ep and t wo-st ep so ot formation mo dels ar e only a vailable f or turbulen t flo ws. 2.Enable the desir ed so ot formation mo del and set the r elated par amet ers, as descr ibed in this sec tion. Setup → Models → Species → Soot Edit... 3.Define the b oundar y conditions f or so ot (and nuclei, if you ar e not using the one-st ep mo del) a t flo w inlets . Setup → Boundar y Conditions 4.In the Solution C ontrols Task P age (p.3606 ), set a suitable v alue f or the so ot (and nuclei, if you ar e not using the one-st ep mo del) under-r elaxa tion fac tor(s). The default v alue is 0.9. If convergenc e cannot b e obtained with this v alue , try a lo wer under-r elaxa tion v alue . Solution → Controls Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1854Modeling P ollutan t Formation5.Perform calcula tions un til convergenc e (tha t is, until the so ot / nuclei r esidual is b elow 10-6) to ensur e that the so ot (and nuclei) field is no longer e volving . Solution → Run C alcula tion Note tha t when Soot-R adia tion In teraction is enabled in the Soot M odel dialo g box, soot equa tions (soot, nuclei, and tar sp ecies , if a vailable) must b e solv ed t ogether with the c ombustion solution to obtain c orrect radia tion c oupling .Therefore, when Soot-R adia tion In teraction is enabled , the soot equa tions ar e not a vailable f or p ollutan t postpr ocessing , but will b e solv ed t ogether with the combustion solution. However, if other p ollutan ts ar e to be solv ed (while so ot/radia tion in teraction is enabled), those p ollutan t equa tions c an b e postpr ocessed . 6.Review the mass fr action of so ot (and nuclei) b y gener ating gr aphic al plots or alphanumer ic reports in the usual w ay. 7.Save a new set of c ase and da ta files , if desir ed. 22.3.1.1. Setting Up the O ne-St ep Mo del You c an enable and set up the one-st ep so ot formation mo del b y using the Soot M odel D ialog Box (p.3343 ) (Figur e 22.11: The S oot M odel D ialog Box for the One-S tep M odel (p.1856 )). Setup → Models → Species → Soot Edit... 1855Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Soot FormationFigur e 22.11: The S oot M odel D ialo g Box for the One-S tep M odel 1.Under Model, selec t One-S tep.The dialo g box will e xpand t o sho w the appr opriate inputs . 2.Define the fuel and o xidiz er sp ecies . Under Species D efinition , selec t the fuel in the Fuel drop-do wn list and the o xidiz er in the Oxidan t drop-do wn list. If you ar e using the non-pr emix ed mo del f or the combustion c alcula tion and y our fuel str eam c onsists of a mix ture of c omp onen ts, you should cho ose the most appr opriate sp ecies as the Fuel species f or the so ot formation mo del. Similar ly, the most signi- ficant oxidizing c omp onen t (for e xample , O2) should b e selec ted as the Oxidan t. 3.If you w ant to include the eff ects of so ot formation on the r adia tion absor ption c oefficien t, enable Soot- Radia tion In teraction in the Options group b ox. For mor e details , see The E ffect of S oot on the A bsor p- tion C oefficien t in the Theor y Guide . 4.Define the f ollowing Process P aramet ers: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1856Modeling P ollutan t FormationStoichiometr y for S oot C ombustion is the mass st oichiometr y, , in Equa tion 14.131 in the Theor y Guide , which c omput es the so ot combustion r ate.The default v alue of 2.6667 assumes tha t the so ot is pur e carbon and the o xidiz er is O2. Stoichiometr y for F uel C ombustion is the mass st oichiometr y, , in Equa tion 14.131 in the Theor y Guide , which c omput es the so ot combustion r ate.The default v alue supplied b y ANSY S Fluen t (3.6363) is f or combustion of pr opane (C3H8) by oxygen (O2). 5.Set the Modeling P aramet ers tha t are used in Equa tion 14.128 ,Equa tion 14.130 , and Equa tion 14.131 in the Theor y Guide : Soot F ormation C onstan t is the par amet er (kg/n-m-s) in Equa tion 14.128 in the Theor y Guide . Equiv alenc e Ratio E xponen t is the e xponen t in Equa tion 14.128 in the Theor y Guide . Equiv alenc e Ratio M inimum and Equiv alenc e Ratio M aximum are the minimum and maximum v alues of the fuel equiv alenc e ratio in Equa tion 14.128 in the Theor y Guide .This equa tion will b e solv ed only if Equiv alenc e Ratio Minimum Equiv alenc e Ratio M aximum ; if falls outside of this r ange , it is assumed tha t soot does not f orm. Activation Temp erature of S oot F ormation R ate is the t erm in Equa tion 14.128 in the Theor y Guide . Magnussen C onstan t for S oot C ombustion is the c onstan t used in the r ate expressions go verning the so ot combustion r ate (Equa tion 14.130 and Equa tion 14.131 in the Theor y Guide ). Note tha t the default v alues f or these par amet ers ar e for pr opane fuel [23] (p.4006 ),[139] (p.4012 ), which are valid f or a wide r ange of h ydrocarbon fuels . 22.3.1.2. Setting Up the Two-St ep Mo del You c an enable and set up the t wo-st ep so ot formation mo del b y using the Soot M odel D ialog Box (p.3343 ) (Figur e 22.12: The S oot M odel D ialog Box for the Two-Step M odel (p.1858 )). Setup → Models → Species → Soot Edit... 1857Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Soot FormationFigur e 22.12: The S oot M odel D ialo g Box for the Two-Step M odel 1.Under Model, selec t Two-Step.The dialo g box will e xpand t o sho w the appr opriate inputs . Imp ortant Note tha t the t wo-st ep Tesner mo del should only b e used when the edd y-dissipa tion model is used t o define the turbulenc e-chemistr y interaction. 2.Under Species D efinition , selec t the fuel in the Fuel drop-do wn list and the o xidiz er in the Oxidan t drop-do wn list. If you ar e using the non-pr emix ed mo del f or the c ombustion c alcula tion and y our fuel stream c onsists of a mix ture of c omp onen ts, you should cho ose the most appr opriate sp ecies as the Fuel species f or the so ot formation mo del. Similar ly, the most signific ant oxidizing c omp onen t (for e x- ample , O2) should b e selec ted as the Oxidan t. 3.If you w ant to include the eff ects of so ot formation on the r adia tion absor ption c oefficien t, enable Soot- Radia tion In teraction in the Options group b ox. For mor e details , see The E ffect of S oot on the A bsor p- tion C oefficien t in the Theor y Guide . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1858Modeling P ollutan t Formation4.Define the f ollowing Process P aramet ers: Mean D iamet er of S oot P article ,Mean D ensit y of S oot P article are the assumed a verage diamet er and a verage densit y of the so ot par ticles in the c ombustion sy stem, used t o comput e the so ot par ticle mass in Equa tion 14.134 in the Theor y Guide . Note tha t the default v alues f or so ot densit y and diamet er ar e tak en fr om [72] (p.4009 ). Stoichiometr y for S oot C ombustion is the mass st oichiometr y in Equa tion 14.131 in the Theor y Guide , which c omput es the so ot combustion r ate.The default v alue of 2.6667 assumes tha t the so ot is pur e carbon and the o xidiz er is O2. Stoichiometr y for F uel C ombustion is the mass st oichiometr y, , in Equa tion 14.131 in the Theor y Guide , which c omput es the so ot combustion r ate.The default v alue supplied b y ANSY S Fluen t (3.6363) is f or combustion of pr opane ( ) by oxygen ( ). 5.Set the Modeling P aramet ers tha t are used in Equa tion 14.130 ,Equa tion 14.131 ,Equa tion 14.134 , Equa tion 14.136 , and Equa tion 14.137 in the Theor y Guide : Limiting N uclei F ormation R ate is the limiting v alue of the k inetic nuclei f ormation r ate, in Equa tion 14.137 in the Theor y Guide . Below this limiting v alue , the br anching and t ermina tion t erm, ( ) in Equa tion 14.136 in the Theor y Guide , is not included . Nuclei Br anching-T ermina tion C oefficien t is the t erm in Equa tion 14.136 in the Theor y Guide . Nuclei C oefficien t of Linear Termina tion on S oot is the t erm in Equa tion 14.136 in the Theor y Guide . Pre-Exponen tial C onstan t of N uclei F ormation is the pr e-exponen tial t erm in the k inetic nuclei f ormation t erm,Equa tion 14.137 in the Theor y Guide . Activation Temp erature of N uclei F ormation R ate is the t erm in the k inetic nuclei f ormation t erm,Equa tion 14.137 in the Theor y Guide . Alpha f or S oot F ormation R ate is , the c onstan t in the so ot formation r ate equa tion, Equa tion 14.134 in the Theor y Guide . Beta f or S oot F ormation R ate is , the c onstan t in the so ot formation r ate equa tion, Equa tion 14.134 in the Theor y Guide . Magnussen C onstan t for S oot and N uclei C ombustion is the c onstan t used in the r ate expressions go verning the so ot combustion r ate (Equa tion 14.130 and Equa tion 14.131 in the Theor y Guide ). The default v alues f or the t wo-st ep mo del ar e the same as in M agnussen and Hjer tager [72] (p.4009 ) (for ac etylene flame), except f or , which is assumed t o ha ve the or iginal v alue fr om Tesner et al.[135] (p.4012 ). If your mo del in volves pr opane fuel r ather than ac etylene , = 3.5x108[5] (p.4005 ) is recommended . For b est r esults , you should mo dify b oth of these par amet ers using empir ically de- termined inputs f or y our sp ecific c ombustion sy stem. 1859Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Soot Formation22.3.1.3. Setting Up the Moss-Br ookes Mo del and the H all E xtension You c an enable and set up the M oss-B rookes and M oss-B rookes-Hall so ot formation mo dels b y using the Soot M odel D ialog Box (p.3343 ) (Figur e 22.13: The S oot M odel D ialog Box for the M oss-B rookes Model (p.1860 )). Setup → Models → Species → Soot Edit... Figur e 22.13: The S oot M odel D ialo g Box for the M oss-Br ookes M odel 1.Under Model, selec t Moss-Br ookes or Moss-Br ookes-H all.The dialo g box will e xpand t o sho w the ap- propriate inputs . Note the f ollowing ab out these mo dels: •The Moss-Br ookes mo del w as or iginally pr oposed f or so ot pr edic tion in methane flames . However, it can b e equally applic able t o higher h ydrocarbon sp ecies b y appr opriately mo difying the so ot pr e- cursor and par ticipa ting sur face gr owth sp ecies . •The Moss-Br ookes-H all mo del is applic able f or higher h ydrocarbon fuels (f or e xample , kerosene) and will only b e available when C2H2, C6H6, C6H5, and H2 are pr esen t in the gas phase sp ecies list. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1860Modeling P ollutan t Formation2.Define the pr ecursor sp ecies in the Species D efinition group b ox.When suitable pr ecursor sp ecies ar e presen t in the sp ecies list , you c an selec t species-list from the Precursor fr om drop-do wn list , and then selec t the Soot P recursor species and the Surface Growth species fr om the selec tion lists . Note tha t for the Moss-Br ookes mo del, you c an selec t acetylene ( c2h2 ), eth ylene ( c2h4 ), and/or b enzene ( c6h6 ) for the Soot P recursor ; if neither ar e pr esen t or if y ou w ould lik e to sp ecify a diff erent precursor c orrel- ation, then cur ve fitting will b e used t o det ermine the pr ecursor and sur face gr owth sp ecies mass fr actions (see Species D efinition f or the M oss-B rookes M odel with a U ser-D efined P recursor C orrelation (p.1864 ) for further details r egar ding cur ve fitting). 3.Specify ho w turbulen t fluc tuations will b e acc oun ted f or in the so ot formation c alcula tions b y defining the turbulenc e par amet ers in the Turbulenc e In teraction M ode group b ox. Selec t one of the options in the PDF M ode drop-do wn list: •Selec t none to ignor e turbulenc e and use laminar so ot rate calcula tions . •Selec t temp erature to tak e into acc oun t fluc tuations of t emp erature. •Selec t temp erature/sp ecies to tak e into acc oun t fluc tuations of t emp erature and mass fr action of the sp ecies selec ted in the Species drop-do wn list (which app ears when y ou selec t this option). •(non-pr emix ed and par tially pr emix ed c ombustion c alcula tions only) S elec t mix ture fraction to tak e into acc oun t fluc tuation in the mix ture fraction(s). This is the r ecommended appr oach, as it gener ally yields the b est r esults and accur acy. Imp ortant When mo deling the f ormation of other p ollutan ts along with so ot, you should c ompar e the selec tions made in the PDF M ode drop-do wn lists in the Turbulenc e In teraction Mode tab of the NOx Model D ialog Box (p.3332 ) and the Turbulenc e In teraction M ode group b oxes of the SOx M odel and Soot M odel dialo g boxes. If mix ture fr action is selec ted in an y of these dialo g boxes, then it must b e selec ted in all of the others as well. The mix ture fr action option is a vailable only if y ou ar e using either the non-pr emix ed or par tially premix ed c ombustion mo del t o mo del the r eacting sy stem. If you use the mix ture fr action option, the instan taneous t emp eratures and sp ecies c oncentrations ar e tak en fr om the PDF lo ok-up table as a func tion of mix ture fraction and en thalp y and the instan taneous so ot pr oduc tion r ates ar e calcula ted a t each c ell.The PDF used f or c onvoluting the instan taneous so ot rates is the same as the one used t o comput e the mean flo w-field pr operties. For e xample , for single-mix ture fraction models the b eta PDF is used , and f or two-mix ture fraction mo dels , the b eta or the double delta PDF c an b e used .The PDF in t erms of mix ture fraction is c alcula ted fr om the v alues of mean mixture fraction and v arianc e at each c ell, and the instan taneous so ot rates ar e convolut ed with the mix ture fraction PDF t o yield the mean r ates in turbulen t flo w. Note When mix ture fr action is selec ted as PDF mo de, ANSY S Fluen t calcula tes and tabula tes the so ot rates apr iori for fast er computa tions of so ot rates.The so ot rates ar e tabula ted at the first so ot it eration and a message Performing Pollutant PDF integrations... 1861Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Soot Formationis displa yed in the F luen t console . 4.If you selec ted temp erature or temp erature/sp ecies for the PDF M ode, you should define the f ollowing paramet ers in the Turbulenc e In teraction M ode group b ox: PDF Type allows you t o sp ecify the shap e of the PDF , which is then in tegrated t o obtain mean r ates for the temp erature and (if y ou selec ted temp erature/sp ecies for the PDF M ode) the sp ecies . If you selec t beta, the PDF will b e mo deled using Equa tion 14.108 in the Theor y Guide . If you selec t gaussian , the PDF will b e mo deled using Equa tion 14.111 in the Theor y Guide . PDF P oints allows you t o sp ecify the numb er of p oints used t o integrate the b eta or G aussian func tion in Equa- tion 14.105 or Equa tion 14.106 in the Theor y Guide on a hist ogram basis .The default v alue of 10 is a minimum v alue . It is r ecommended tha t you r un the c alcula tion with this minimum v alue t o con- vergenc e, and then k eep incr easing the v alue (f or e xample , 20–25) un til the p ollutan ts of in terest stop changing . Incr easing this v alue ma y impr ove accur acy, but will also incr ease the c omputa tion time . Temp erature Varianc e allows you t o sp ecify the f orm of tr ansp ort equa tion tha t is solv ed t o calcula te the t emp erature varianc e.The default selec tion is algebr aic, which is an appr oxima te form of the tr ansp ort equa tion (see Equa tion 14.114 of the Theor y Guide ).You ha ve the option of selec ting transp orted to inst ead solv e Equa tion 14.113 in the Theor y Guide .Though the transp orted form is mor e exact, it is also mor e expensiv e computa tionally . Tmax Option provides v arious options f or det ermining the maximum limit of the t emp erature used f or the in teg- ration of the PDF (see Equa tion 8.44 in the Fluent Theor y Guide ) to calcula te mean r ates for turbulen t fluctuations of so ot.The default selec tion is global-tmax , which sets the limit as the maximum temp erature in the flo w field .You c an selec t local-tmax if you w ould r ather obtain c ell-based max- imum t emp erature limits b y multiplying the lo cal cell mean t emp erature by the v alue en tered in Tmax F actor.You c an selec t specified-tmax to set the limit f or each c ell to be the v alue en tered in Tmax . Finally , if you ha ve compiled a user-defined func tion f or the so ot rate and loaded the libr ary into ANSY S Fluen t, then y ou c an selec t user-defined so tha t the limit is sp ecified b y a user-defined func tion. Species only app ears if y ou ha ve selec ted temp erature/sp ecies for the PDF M ode.Your selec tion in this drop-do wn menu det ermines which sp ecies ’ mass fr action is included in the so ot formation c alcula- tions . Imp ortant Note tha t the sp ecies v arianc e will alw ays be calcula ted using the algebr aic f orm of the tr ansp ort equa tion ( Equa tion 14.114 in the Theor y Guide ). 5.Under Process P aramet ers, enter inf ormation ab out the mass and mean densit y of the so ot par ticles: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1862Modeling P ollutan t FormationMass of Incipien t Soot P articles is in Equa tion 14.142 and Equa tion 14.144 in the Theor y Guide . Note tha t this v alue w as assumed to be 144 k g/kmol (12 c arbon a toms) in the w ork of B rookes and M oss, wher eas the Hall e xtension model assumed it t o be 1200 k g/kmol (100 c arbon a toms). Mean D ensit y of S oot P article is in Equa tion 14.141 and Equa tion 14.144 in the Theor y Guide . Note tha t this v alue w as assumed to be 1800 k g/m3 in the w ork of B rookes and M oss [19] (p.4006 ), wher eas Hall et al. [45] (p.4007 ) assumed it to be 2000 k g/m3. 6.Selec t the Soot O xida tion M odel.Your choic es include the Fenimor e-Jones mo del, as or iginally used in Brookes and M oss’ work, or the Lee extended mo del. The Lee mo del will mo del so ot o xida tion due to hydroxyl radic als as in the Fenimor e-Jones mo del, as w ell as the o xida tion due t o molecular o xygen. 7.Set the Modeling P aramet ers: [OH] M odel allows you t o sp ecify the metho d by which the OH r adic al concentration is c alcula ted.The r ecom- mended selec tion fr om the dr op-do wn list is instan taneous , although this option is only a vailable when OH is a vailable in the sp ecies list and is c alcula ted b y the c ombustion mo del. The other option is the par tial-equilibr ium mo del, which nec essita tes the a vailabilit y of O r adic al concentration within the field . [O] M odel must b e defined when y ou ha ve selec ted par tial-equilibr ium for the [OH] M odel, and sp ecifies the metho d by which the O r adic al concentration is c alcula ted.The options include equilibr ium ,par tial- equilibr ium , and instan taneous . 8.If you w ant to include the eff ects of so ot formation on the r adia tion absor ption c oefficien t, enable Soot- Radia tion In teraction in the Options group b ox. For mor e details , see The E ffect of S oot on the A bsor p- tion C oefficien t in the Theor y Guide . Note tha t in ANSY S Fluen t, the o xida tion r ate sc aling par amet er ( in Equa tion 14.142 in the Theor y Guide ) is set t o unit y. If you w ould lik e to change the v alue of this par amet er, you c an use the define/models/soot-parameters text command . A lo wer v alue will r educ e the amoun t of soot o xida tion. 22.3.1.3.1. Specifying a User -Defined F unc tion for the S oot O xidation R ate You c an cho ose t o sp ecify a user-defined func tion f or the so ot o xida tion r ate.The c ompiled UDF hook is a vailable fr om the User D efined O xida tion R ate drop-do wn list of the Soot M odel dialo g box. See DEFINE_SOOT_OXIDATION_RATE in the Fluent C ustomization Manual for details ab out user-defined func tions . 22.3.1.3.2. Specifying a User -Defined F unc tion for the S oot P recursor C onc entr ation You c an cho ose t o sp ecify a user-defined func tion f or the so ot o xida tion r ate.The c ompiled UDF hook is a vailable fr om the User D efined P recursor drop-do wn list in the Species D efinition group box of the Soot M odel dialo g box. See DEFINE_SOOT_PRECURSOR in the Fluent C ustomization Manual for details ab out user-defined func tions . 1863Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Soot Formation22.3.1.3.3. Species D efinition for the Moss-Br ookes Mo del with a User -Defined P recursor Correlation ANSY S Fluen t acc epts the f ollowing as p ossible pr ecursor sp ecies f or the M oss-B rookes mo del: C2H2, C6H6, and C2H4. If none of these sp ecies ar e pr esen t in the sp ecies list (as is of ten the c ase when using the edd y-dissipa tion mo del) or if y ou w ould pr efer to sp ecify a diff erent precursor c orrelation, your setup f or the M oss-B rookes mo del will b e diff erent than not ed pr eviously . Under such cir cum- stanc es, you should selec t user-c orrelation from the Precursor fr om drop-do wn list in the Species Definition group b ox (not e tha t this is only option p ossible when the appr opriate sp ecies ar e not presen t).The Soot M odel D ialog Box (p.3343 ) will then b e as sho wn in Figur e 22.14: The S oot M odel Dialog Box for the M oss-B rookes M odel with a U ser-D efined P recursor C orrelation (p.1864 ).The par a- met ers y ou set in the Species D efinition group b ox allo w ANSY S Fluen t to calcula te a mix ture fraction based on the mass fr actions of the o xidan t and the c arbon/h ydrogen c ontribut ed b y a designa ted fuel sp ecies .The pr ecursor sp ecies mass fr action will then b e comput ed as a func tion (which y ou will also define) of this mix ture fraction. Figur e 22.14: The S oot M odel D ialo g Box for the M oss-Br ookes M odel with a U ser-D efined Precursor C orrelation 1.In the Species D efinition group b ox, selec t a Fuel species and en ter the r elated Fuel C arb on N umb er and Fuel H ydrogen N umb er for use in the mix ture fraction c alcula tion. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1864Modeling P ollutan t Formation2.Enter the Molecular Weigh t of P recursor (the default v alue is f or ac etylene). 3.Make a selec tion in the Precursor C orrelation drop-do wn list t o indic ate ho w the pr ecursor mass fraction will b e related t o the mix ture fraction. A piec ewise-p olynomial profile is defined b y default. Imp ortant Note tha t the default v alues f or the piec ewise-p olynomial profile ar e only v alid f or a methane diffusion flame simula tion, in which b oth the air and fuel initial t emp eratures are set t o 290 K, and ac etylene is assumed as the so ot pr ecursor . If you decide not t o use the default v alues f or Precursor C orrelation , define the c orrelation between the pr ecursor mass fr action and the mix ture fraction. This c orrelation should b e based on a laminar flamelet pr ofile tha t you ha ve gener ated. If possible , you should gener ate the pr ofile using the Species M odel dialo g box (as descr ibed in Setting U p the S teady and U nsteady Diffusion Flamelet M odels (p.1696 )) with Stead y Flamelet selec ted in the Chemistr y tab . If ther e is no mechanism, you c an gener ate the pr ofile using the equilibr ium chemistr y mo del (see Setting U p the E quilibr ium C hemistr y Model (p.1691 ) for details). You ma y also use a thir d-par ty sof tware pack age of y our choic e.You should then apply a cur ve-fitting t echnique t o your gener ated pr ofile , to obtain either a c onstan t value or a piec ewise-p olynomial func tion. In a piec ewise-p olynomial func tion, the laminar flamelet pr ofile is divided in to a numb er of mixture fraction r anges . In each r ange , the pr ecursor sp ecies mass fr action is defined using the f ollowing equa tion: (22.14) wher e is the numb er of c oefficien ts , and is the mix ture fraction. The f ollowing piec ewise- polynomial func tion c orresponds t o the default settings in ANSY S Fluen t: (22.15) 4.To define a piec ewise-p olynomial pr ofile t o relate the pr ecursor mass fr action t o the mix ture fraction, selec t piec ewise-p olynomial from the Precursor C orrelation drop-do wn list and click the Edit... butt on. 1865Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Soot FormationFigur e 22.15: The P iecewise-P olynomial P rofile D ialo g Box In the Piecewise-P olynomial P rofile Piecewise-P olynomial P rofile D ialog Box (p.3404 ), set the following c ontrols: a.Enter the numb er of Ranges . For the e xample sho wn in Equa tion 22.15 (p.1865 ), three ranges of mixture fraction ar e defined , which is the maximum allo wed. b.For the first r ange ( Range = 1), enter the Minimum and Maximum mix ture fraction v alues , and the numb er of Coefficien ts. (Up to eigh t coefficien ts ar e available .) The numb er of c oefficien ts defines the or der of the p olynomial. An input of 1 defines a p olynomial of or der 0, and the mass fr action will b e constan t and equal t o the single c oefficien t. An input of 2 defines a p olynomial of or der 1, and the mass fr action will v ary linear ly with mix ture fraction, and so on. c.Define the v alues f or the c oefficien ts in the Coefficien ts group b ox.The dialo g box in Fig- ure 22.15: The P iecewise-P olynomial P rofile D ialog Box (p.1866 ) sho ws the inputs f or the first r ange of Equa tion 22.15 (p.1865 ). d.Increase the v alue of Range and en ter the Minimum and Maximum mix ture fractions , numb er of Coefficien ts, and the v alues f or the Coefficien ts for the ne xt range . Repeat if ther e is a thir d range . Imp ortant Note when defining the r anges , you must star t with the lo west mix ture fraction range , and then pr oceed in or der t o the highest r ange .The solv er will not sor t them f or y ou. 5.To define a c onstan t profile t o relate the pr ecursor mass fr action t o the mix ture fraction, selec t constan t from the Precursor C orrelation drop-do wn list and en ter a v alue in the acc ompan ying t ext en try box. 22.3.1.4. Setting Up the Metho d of Moments S oot Mo del You c an enable and set up the M etho d of M omen ts mo del b y using the Soot M odel dialo g box (Figur e 22.16: The S oot M odel D ialog Box for the M etho d of M omen ts M odel (p.1867 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1866Modeling P ollutan t FormationSetup → Models → Species → Soot Edit... 1.In the Soot M odel dialo g box under Model, selec t Metho d of M omen ts.The dialo g box will e xpand t o show the appr opriate inputs . Figur e 22.16: The S oot M odel D ialo g Box for the M etho d of M omen ts M odel 2.Specify Numb er O f Momen ts. ANSY S Fluen t will solv e an equal numb er of momen t transp ort equa tions .The default v alue of 3 momen ts w orks reasonably w ell for a wide r ange of applic ations . However, you c an sp ecify up t o 6 momen ts to achie ve higher accur acy. 3.From the Soot M echanism group b ox, selec t an appr opriate option t o use f or so ot mo deling: 1867Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Soot Formation•Detailed CHEMKIN F ormat: allo ws you t o use a so ot mechanism in CHEMKIN f ormat. See Detailed Soot M echanism in the Fluent Theor y Guide for details ab out this option. •Built-In HA CA: allo ws you t o set up the nuclea tion mechanism and use the-built-in HA CA sur face growth and o xida tions mechanisms . See Built-In HA CA M echanism in the Fluent Theor y Guide for details about this option. 4.If you selec ted Detailed CHEMKIN F ormat, perform the f ollowing st eps: Figur e 22.17: The S oot M odel D ialo g Box for the D etailed CHEMKIN F ormat Soot M echanism a.Under Process P aramet ers, specify Normaliza tion P aramet er for M omen ts. The nor maliza tion par amet er is used t o minimiz e numer ical er rors when solving the nor maliz ed soot momen t transp ort equa tions .The default v alue f or this par amet er is enough f or most cases . b.Prior t o using this mo del, you must imp ort the so ot mechanism in a CHEMKIN f ormat thr ough the File menu: File → Imp ort → CHEMKIN M echanism... In the Imp ort CHEMKIN F ormat Mechanism dialo g box tha t op ens, selec t the Imp ort Surface Mechanism option and pr ovide a full pa thname t o the k inetics input file under the Surface group b ox. For mor e inf ormation ab out imp orting so ot mechanisms , see Imp orting a Sur face Kinetic Mechanism in CHEMKIN F ormat (p.1655 ). 5.If you selec ted Built-In HA CA (as sho wn in Figur e 22.16: The S oot M odel D ialog Box for the M etho d of Momen ts M odel (p.1867 )), perform the f ollowing st eps: a.From the Soot N uclea tion M odel group b ox, selec t one of the f ollowing options: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1868Modeling P ollutan t Formation•Use P recursor (default): Enables y ou t o define the pr ecursor sp ecies f or y our so ot pr edic tion sim- ulation. •Specify M echanism : Enables y ou t o pr ovide the nuclea tion r ate and sp ecify nuclea tion as a r eaction between so ot pr ecursors . Using this option, you c an achie ve mor e accur ate results wher e the nuclea tion r ate da ta is a vailable . b.(if Use P recursor is selec ted f or the so ot nuclea tion mo del) U nder the Species D efinition group box, define pr ecursor sp ecies . i.In the Soot P recursor group list (which is p opula ted with all pr ecursors a vailable in y our analy sis), selec t one or mor e pr ecursors . The so ot pr ecursor sp ecies must b e a h ydrocarbon sp ecies . ANSY S Fluen t uses k inetic theor y to calcula te the nuclea tion r ates c onsider ing c oagula tion b etween pr ecursor sp ecies . ii.Click Stick ing C oefficien ts... to sp ecify the stick ing c oefficien t for each pr ecursor in the Stick ing Coefficien ts dialo g box tha t will op en. Figur e 22.18: Stick ing C oefficien ts for S oot P recursors You must sp ecify the stick ing c oefficien t for each pr ecursor b ecause the nuclea tion r ates calcula ted based on k inetic theor y of c ollision of t wo so ot pr ecursors ar e gener ally v ery large, causing numer ical er rors. Imp ortant The default v alue f or a stick ing c oefficien t is c alcula ted based on pr ecursor molecular w eigh t. In gener al, you c an use smaller v alues f or stick ing c oefficien ts for smaller pr ecursors . For guidelines on sp ecifying the stick ing c oefficien ts for precursor sp ecies , see Nuclea tion in the Fluent Theor y Guide . c.(if Specify M echanism is selec ted f or the so ot nuclea tion mo del) C lick Set N uclea tion M echanism... and en ter the r eaction r ates inputs in the Mechanism dialo g box tha t will op en. 1869Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Soot FormationFigur e 22.19: Settings f or the N uclea tion M echanism i.Specify Numb er of nuclea tion r eac tions . The nuclea tion r eactions c an b e single or multi-st ep. ii.For each r eaction, specify the f ollowing: •Reactant species and c orresponding st oichiometr ic coefficien t and r ate exponen t •The Arhenius R ate par amet ers ( Pre-Exponen tial F actor,Activation E nergy, and Temp erature Exponen t) Note The inputs in the Mechanism dialo g box are requir ed only f or reactant sp ecies as the main pr oduc t of sp ecified nuclea tion r eaction is alw ays assumed t o be a so ot nuclei, and all other pr oduc ts ar e not c onsider ed in c alcula tions of so ot nuclea tion rates. d.If you w ant to acc oun t for so ot aggr egate formation, selec t Enable A ggr ega tion M odel In addition t o the momen t transp ort equa tions , ANSY S Fluen t will solv e an equal numb er of the par ticle momen t transp ort equa tions . Onc e you ha ve enabled the aggr egation mo del, you c an sp ecify the f ollowing par amet ers: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1870Modeling P ollutan t FormationCritical diamet er: A v alue of the so ot par ticle diamet er ab ove which the c oagula tion r egime is swit ched fr om c oalesc ent coagula tion t o aggr egate coagula tion. Fractal D imension : A par amet er tha t descr ibes the fr actal str ucture of the aggr egate.Values between 1.7 and 2.0 w ork reasonably go od for the aggr egate coagula tion. Note When the Enable A ggr ega tion M odel option is enabled , the M etho d of M o- men ts mo del t ends t o over-pr edic t the pr oduc tion of so ot.This is due , in par t, to the linear in terpolation of the par ticle momen ts.This asp ect of the o ver- predic tion c an b e overcome b y emplo ying quadr atic in terpolation of the par ticle momen ts. Another r eason f or the o ver-pr edic tion of so ot is due t o ho w ANSY S Fluen t cur rently ignor es the depletion of ac etylene dur ing the so ot c alcula tions . Acetylene is c onsumed dur ing the sur face gr owth of so ot, and sinc e the gas field sta ys frozen and has no k nowledge of the so ot pr ocess, ther eby pr oducing a higher sur face gr owth of so ot, and e ventually higher so ot yields . For inf ormation ab out the aggr egation mo del, see Soot A ggregation in the Fluent Theor y Guide . e.Under Soot S urface Growth Options , specify Soot D ensit y. The gr owth of so ot due t o sur face reactions and depletion due t o oxida tion r eactions ar e modeled using HA CA mechanism (see Surface Growth and O xida tion in the separ ate Theor y Guide ). For reaction r ates and r eaction st eps, ANSY S Fluen t uses default v alues and r equir es no user inputs e xcept f or the so ot sit e densit y. Note You c an sp ecify and/or edit the r eaction r ates of sur face reactions using the define/models/soot-parameters text command . Imp ortant The so ot sit e densit y is alw ays pr ovided in units of numb er of sit es p er cm2 irrespect- ive of the unit sy stem selec ted in ANSY S Fluen t. f.Under Process P aramet ers, specify Mean D ensit y of S oot P article and Normaliza tion P aramet er for M omen ts. The nor maliza tion par amet er is used t o minimiz e numer ical er rors when solving the nor maliz ed soot momen t transp ort equa tions .The default v alue f or this par amet er is sufficien t, and y ou may not need t o change it. g.Specify the Modeling P aramet ers: •[OH] M odel: Specifies the metho d by which the [OH] r adic al concentration is c alcula ted. For OH Model, the f ollowing options ar e available: –instantaneous (recommended wher e possible) 1871Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Soot FormationThis option is only a vailable when OH is pr esen t in the sp ecies list and par ticipa te in the combustion simula tion. –partial-equilibrium This option nec essita tes the a vailabilit y of [O] a tom c oncentration within the field . •[O] M odel (available only if instantaneous is not selec ted f or OH M odel): Specifies the metho d by which the [O] r adic al concentration is c alcula ted.The following options ar e available: –equilibrium –partial-equilibrium –instantaneous 22.3.1.5. Defining B oundar y Conditions for the S oot Mo del At flo w inlet b oundar ies, you must sp ecify the Soot M ass F raction and (when not using the one-st ep model) the Nuclei mass c oncentration. These c orrespond t o in Equa tion 14.126 and Equa- tion 14.140 and in Equa tion 14.132 and Equa tion 14.140 in the Theor y Guide , respectively. Setup → Boundar y Conditions You c an r etain the default inlet v alues of z ero for b oth quan tities or y ou c an en ter nonz ero numb ers as appr opriate for y our c ombustion sy stem. 22.3.1.6. Reporting S oot Q uantities ANSY S Fluen t provides additional r eporting options when y our mo del includes so ot formation. You can gener ate gr aphic al plots or alphanumer ic reports of the f ollowing it ems: •Mass fr action of S oot •Mole fr action of S oot •Soot D ensit y •Soot Volume fr action •Rate of S oot •Normaliz ed C onc entration of N uclei (una vailable f or one-st ep mo del) •Rate of N uclei (una vailable f or one-st ep mo del) •Rate of S oot M ass N uclea tion (Moss-B rookes and M oss-B rookes-Hall mo dels only) •Rate of S urface Growth (Moss-B rookes and M oss-B rookes-Hall mo dels only) •Rate of O xida tion (Moss-B rookes and M oss-B rookes-Hall mo dels only) •Rate of N uclea tion (Moss-B rookes and M oss-B rookes-Hall mo dels only) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1872Modeling P ollutan t Formation•Rate of C oagula tion (Moss-B rookes and M oss-B rookes-Hall mo dels only) •Soot S urface Area (Metho d of M omen ts mo del only) •Soot M ean D iamet er (Metho d of M omen ts mo del only) •Conc entration of soot species-n (Metho d of M omen ts mo del only) •Site fraction of soot species-n (Metho d of M omen ts mo del only) •Normaliz ed so ot momen ts (Metho d of M omen ts mo del only) •Normaliz ed S oot A ggr ega tion M omen ts (Metho d of M omen ts mo del with A ggregation only) •Average N umb er of P articles in S oot A ggr ega te (Metho d of M omen ts mo del with A ggregation only) •Primar y Particle D iamet er (Metho d of M omen ts mo del with A ggregation only) These par amet ers ar e contained in the Soot... categor y of the v ariable selec tion dr op-do wn list tha t app ears in p ostpr ocessing dialo g boxes. 22.4. Using the D ecoupled D etailed C hemistr y M odel The dec oupled detailed chemistr y pollutan t mo del is used t o postpr ocess slo wly-f orming , trace pollutan t species on a st eady-sta te flo w field using detailed chemic al kinetic mechanisms . For theor etical inf orm- ation, refer to Decoupled D etailed C hemistr y Model.The r ecommended pr ocedur e is as f ollows: 1.Calcula te your st eady combustion pr oblem using the S pecies Transp ort, Non-P remix ed, Partially-P remix ed, or PDF Transp ort mo dels in ANSY S Fluen t. It is r ecommended tha t you sa ve your c ase and da ta file , as it may be difficult t o revert to the or iginal settings af ter you set up the dec oupled detailed chemistr y pollutan t model. 2.Enable the Decoupled D etailed C hemistr y option in the Decoupled D etailed C hemistr y dialo g box.To access this dialo g box, mak e sur e tha t either the non-pr emix ed or par tially pr emix ed mo del is selec ted, or that reactions ar e enabled if the sp ecies tr ansp ort or PDF tr ansp ort mo dels ar e used . Setup → Models → Species → Decoupled D etailed C hemistr y Edit... Figur e 22.20: The D ecoupled D etailed C hemistr y D ialo g Box 1873Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the D ecoupled D etailed C hemistr y Model3.Click Imp ort CHEMKIN M echanism... to imp ort your detailed chemistr y mechanism in CHEMKIN f ormat. The Imp ort CHEMKIN F ormat Mechanism dialo g box (descr ibed in Imp orting a Volumetr ic Kinetic Mechanism in CHEMKIN F ormat (p.1624 )) will op en, wher e you will br owse to the file . After the CHEMKIN mechanism is imp orted, the Decoupled D etailed C hemistr y dialo g box will e xpand t o include the sp ecies . The sp ecies in the initial detailed chemic al kinetic mechanism used t o obtain the st eady-sta te solution app ear in the Original S pecies list. The sp ecies in the detailed chemistr y mechanism y ou ha ve im- ported app ear in the Pollutan t Species list. Note tha t if the sp ecies is pr esen t in b oth mechanisms , it will b e list ed only under Original S pecies and will not b e available as a p ollutan t sp ecies . 4.Selec t the Pollutan t Species and click Apply .The p ollutan t species ar e typic ally slo wly f orming (far fr om chemic al equilibr ium), and o ccur a t miniscule mass fr actions . ANSY S Fluen t will cr eate a mix ture ma terial called pollutan t-mix ture and enable the Species Transp ort mo del with the Stiff C hemistr y Solver. All species in the imp orted mechanism tha t were not in the or iginal c ombustion mo del and ar e not p ollutan t species will b e calcula ted b y chemic al equilibr ium a t the c ell temp erature.The solution of all tr ansp ort equa tions , except the selec ted p ollutan t species , are disabled . Note Species tha t are not iden tified as p ollutan ts and do not par ticipa te in the r eactions amongst the p ollutan t sp ecies ar e elimina ted. Similar ly, reactions in the imp orted CHEMKIN mechanism, which do not include an y pollutan t sp ecies ar e also elimina ted. 5.Click Integration P aramet ers... to op en the Integration P aramet ers dialo g box. Set the ISAT Paramet ers, such as the ISAT Error Toler anc e and Max. Storage . An ISAT Error Toler anc e of 1e-5 is r ecommended , and Max. Storage should b e set t o a lar ge fr action of the fr ee R AM memor y available .To lear n mor e ab out setting in tegration par amet ers, refer to Using ISA T (p.1794 ). 6.Define the b oundar y conditions f or all p ollutan ts at flo w inlets (these ar e usually z ero). Setup → Boundar y Conditions 7.Iterate un til convergenc e. Solution → Run C alcula tion 8.Review the mass fr actions of p ollutan ts by gener ating gr aphic al plots or alphanumer ic reports in the usual way. 9.Save a new set of c ase and da ta files , if desir ed. File → Write → Case & D ata... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1874Modeling P ollutan t FormationChapt er 23: Predic ting A erodynamic ally G ener ated N oise This chapt er pr ovides an o verview of ANSY S Fluen t’s appr oaches t o computing aer odynamic ally gener ated sound , the mo del setup , and the pr ocedur e for c omputing sound . For mor e inf ormation ab out the un- derlying theor y behind aer odynamic ally gener ated sound , see Aerodynamic ally G ener ated N oise in the Theor y Guide . 23.1. Overview 23.2. Using the Ff owcs Williams and Ha wkings A coustics M odel 23.3. Using the A coustics Wave Equa tion M odel 23.4. Using the B roadband N oise S ource Models 23.1. Overview Consider ing the br eadth of the discipline and the challenges enc oun tered in aer odynamic ally gener ated noise , it is not sur prising tha t a numb er of c omputa tional appr oaches ha ve been pr oposed o ver the years whose sophistic ation, applic abilit y, and c ost widely v ary. ANSY S Fluen t off ers thr ee appr oaches t o computing aer odynamic ally gener ated noise: a dir ect appr oach, a hybrid appr oach, and an appr oach tha t utiliz es br oadband noise sour ce mo dels .Within the h ybrid appr oach, Fluen t off ers the t wo metho ds, which ar e the in tegral metho d by Ffowcs Williams and Hawkings , and a diff erential sound pr opaga tion metho d based on a finit e volume solv er for a w ave equa tion. For additional inf ormation, see the f ollowing sec tions: 23.1.1. Direct Metho d 23.1.2. Integral M etho d by Ffowcs Williams and Ha wkings 23.1.3. Metho d Based on Wave Equa tion 23.1.4. Broadband N oise S ource Models 23.1.1. Direct Metho d In this metho d, both gener ation and pr opaga tion of sound w aves ar e dir ectly c omput ed b y solving the appr opriate fluid d ynamics equa tions . Predic tion of sound w aves alw ays requir es time-accur ate solutions t o the go verning equa tions . Further mor e, in most pr actical applic ations of the dir ect metho d, one has t o emplo y go verning equa tions tha t are capable of mo deling visc ous and turbulenc e eff ects, such as unst eady Navier-S tokes equa tions (tha t is, DNS), RANS equa tions , and filt ered equa tions used in LES and h ybrid R ANS-LES mo dels . The dir ect metho d is ther efore computa tionally difficult and e xpensiv e inasmuch as it r equir es highly accur ate numer ics, very fine c omputa tional meshes all the w ay to receivers, and ac oustic ally nonr eflec t- ing b oundar y conditions .The c omputa tional c ost b ecomes pr ohibitiv e when sound is t o be pr edic ted in the far field (f or e xample , hundr eds of chor d-lengths in the c ase of an air foil). The dir ect metho d becomes f easible when r eceivers ar e in the near field (f or e xample , cabin noise). In man y such situa tions involving near-field sound , sounds (or pseudo-sounds f or tha t ma tter) ar e pr edominan tly due t o lo cal hydrodynamic pr essur e, which c an b e pr edic ted with a r easonable c ost and accur acy. 1875Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Since sound pr opaga tion is dir ectly r esolv ed in this metho d, you w ould nor mally solv e the c ompr essible form of the go verning equa tions (f or e xample , compr essible R ANS equa tions , compr essible f orm of filtered equa tions f or LES). Only in situa tions wher e the flo w is lo w subsonic and the r eceivers in the near field sense pr imar ily lo cal hydrodynamic pr essur e fluc tuations (tha t is, pseudo sound) c an inc om- pressible flo w formula tions b e used . But this inc ompr essible tr eatmen t will also not allo w you t o sim- ulate resonanc e and f eedback phenomena. 23.1.2. Integral M etho d by Ff owcs Williams and H awkings For pr edic tions of mid- t o far-field noise , the metho ds based on Ligh thill’s ac oustic analo gy [66] (p.4008 ) offer viable alt ernatives to the dir ect metho d. In this appr oach, the near-field flo w obtained fr om ap- propriate go verning equa tions such as unst eady RANS equa tions , DES, SAS, SDES, SBES, or LES ar e used t o pr edic t the sound with the aid of analytic ally der ived in tegral solutions t o wave equa tions . The ac oustic analo gy essen tially dec ouples the pr opaga tion of sound fr om its gener ation, allo wing one t o separ ate the flo w solution pr ocess fr om the ac oustics analy sis. ANSY S Fluen t off ers a metho d based on the Ff owcs Williams and Ha wkings (FW-H) f ormula tion [33] (p.4006 ).The FW-H f ormula tion adopts the most gener al form of Ligh thill’s ac oustic analo gy, and is capable of pr edic ting sound gener ated b y equiv alen t acoustic sour ces such as monop oles , dip oles , and quadr upoles . ANSY S Fluen t adopts a time-domain in tegral formula tion wher ein time hist ories of sound pr essur e, or ac oustic signals , at prescr ibed r eceiver lo cations ar e dir ectly c omput ed b y evalua ting a few sur face in tegrals. Time-accur ate solutions of the flo w-field v ariables , such as pr essur e, velocity comp onen ts, and densit y on sour ce (emission) sur faces, are requir ed t o evalua te the sur face in tegrals.Time-accur ate solutions can b e obtained fr om unst eady Reynolds-a veraged N avier-S tokes (UR ANS) equa tions , large edd y sim- ulation (LES), or h ybrid R ANS-LES mo dels as appr opriate for the flo w at hand and the f eatures tha t you w ant to captur e (for e xample , vortex shedding). The sour ce sur faces c an b e plac ed not only on imp ermeable w alls, but also on in terior (p ermeable) sur faces, which enables y ou t o acc oun t for the contributions fr om the quadr upoles enclosed b y the sour ce sur faces. Both br oadband and t onal noise can b e pr edic ted dep ending on the na ture of the flo w (noise sour ce) b eing c onsider ed, turbulenc e model emplo yed, and the time sc ale of the flo w resolv ed in the flo w calcula tion. The FW-H ac oustics mo del in ANSY S Fluen t allo ws you t o selec t multiple sour ce sur faces and r eceivers. It also p ermits y ou either t o sa ve the sour ce da ta for a futur e use , or t o carry out an “on the fly ” acoustic c alcula tion simultaneously as the tr ansien t flo w calcula tion pr oceeds , or b oth. Sound pr essur e signals ther efore obtained c an b e pr ocessed using the fast F ourier tr ansf orm (FFT ) and asso ciated postpr ocessing c apabilities t o comput e and plot such ac oustic quan tities as the o verall sound pr essur e level (SPL) and p ower sp ectra. One imp ortant limita tion of ANSY S Fluen t’s FW-H mo del is tha t it is applic able only t o pr edic ting the propaga tion of sound t oward free spac e.Therefore, while the mo del c an b e legitima tely used t o pr edic t far-field noise due t o external aer odynamic flo ws, such as the flo ws around gr ound v ehicles and air craft, it cannot b e used f or pr edic ting the noise pr opaga tion inside duc ts or w all-enclosed spac e. 23.1.3. Metho d Based on Wave Equa tion In this h ybrid simula tion metho d, which is in tended t o simula te aer oacoustics of lo w M ach numb er flows, the inc ompr essible flo w mo del is used f or the c alcula tion of sound sour ces, while the diff erential wave equa tion is used t o calcula te the pr opaga tion of sound gener ated b y these sour ces.The ac oustics wave equa tion implemen ted in ANSY S Fluen t is der ived fr om the ac oustics p erturba tion equa tions b y Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1876Predic ting A erodynamic ally G ener ated N oiseEwert and Schr oeder [r ef] under the assumption of c onstan t densit y flo w.The main ad vantages of this model ar e: • Extended applic abilit y compar ed t o the Ff owcs Williams and Ha wking in tegral solv er, which c an b e used only t o mo del the sound pr opaga tion in op en spac e (see Integral M etho d by Ffowcs Williams and Ha wkings (p.1876 )). • Simple and c onvenien t workflow of h ybrid aer oacoustics simula tions , without an y da ta e xchange between diff erent sof tware comp onen ts via disk files , and without the in terpolation of sound sour ces on a diff erent mesh. A tr ansien t co-simula tion of fluid flo w and noise pr opaga tion using the same domain and mesh has b een chosen f or the cur rent implemen tation. 23.1.4. Broadband N oise S our ce M odels In man y pr actical applic ations in volving turbulen t flo ws, noise do es not ha ve an y distinc t tones , and the sound ener gy is c ontinuously distr ibut ed o ver a br oad r ange of fr equencies . In those situa tions involving broadband noise , statistic al turbulenc e quan tities r eadily c omputable fr om R ANS equa tions can b e utiliz ed, in c onjunc tion with semi-empir ical correlations and Ligh thill’s ac oustic analo gy, to shed some ligh t on the sour ce of br oadband noise . ANSY S Fluen t off ers se veral such sour ce mo dels tha t enable y ou t o quan tify the lo cal contribution (p er unit sur face ar ea or v olume) t o the t otal ac oustic p ower gener ated b y the flo w.They include the f ol- lowing: •Proudman ’s formula •jet noise sour ce mo del •boundar y layer noise sour ce mo del •sour ce terms in the linear ized E uler equa tions •sour ce terms in Lille y’s equa tion Consider ing tha t one w ould ultima tely w ant to come up with some measur es to mitiga te the noise gener ated b y the flo w in question, the sour ce mo dels c an b e emplo yed t o extract useful diagnostics on the noise sour ce to det ermine which p ortion of the flo w is pr imar ily responsible f or the noise gener ation. Note, however, tha t these sour ce mo dels do not pr edic t the sound a t receivers. Unlike the dir ect metho d and the FW-H in tegral metho d, the br oadband noise sour ce mo dels do not requir e transien t solutions t o an y go verning fluid d ynamics equa tions . All the sour ce mo dels need is wha t typic al RANS mo dels w ould pr ovide , such as the mean v elocity field , turbulen t kinetic ener gy ( ) and the dissipa tion r ate ( ).Therefore, the use of br oadband noise sour ce mo dels r equir es the least computa tional r esour ces. 23.2. Using the Ff owcs Williams and H awkings A coustics M odel The pr ocedur e for c omputing sound using the FW-H ac oustics mo del in ANSY S Fluen t consists lar gely of two steps. In the first st ep, a time-accur ate flo w solution is gener ated fr om which time hist ories of the r elevant variables (f or e xample , pressur e, velocity, and densit y) on the selec ted sour ce sur faces ar e 1877Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the Ff owcs Williams and Ha wkings A coustics M odelobtained . In the sec ond st ep, sound pr essur e signals a t the user-sp ecified r eceiver lo cations ar e comput ed using the sour ce da ta collec ted dur ing the first st ep. Imp ortant Note tha t you c an also use the FW-H mo del f or a st eady-sta te simula tion in the c ase wher e your mo del has a single mo ving r eference frame . Here, the thick ness and loading noise due to the motion of the noise sour ces is c omput ed using the FW-H in tegrals (see Equa tion 15.5 and Equa tion 15.6 in the Theor y Guide ), except tha t the t erm in volving the time der ivative of sur face pr essur e (contribution t o in Equa tion 15.6 in the Theor y Guide ) is set t o zero. In computing sound pr essur e using the FW-H in tegral solution, ANSY S Fluen t uses a so-c alled “forward- time pr ojec tion ” to acc oun t for the time dela y between the emission time (the time a t which the sound is emitt ed fr om the sour ce) and the r eception time (the time a t which the sound ar rives a t the r eceiver location). The f orward-time pr ojec tion appr oach enables y ou t o comput e sound a t the same time “on the fly ” as the tr ansien t flo w solution pr ogresses , without ha ving t o sa ve the sour ce da ta. In this sec tion, the pr ocedur e for setting up and using the FW-H ac oustics mo del is outlined first , followed by detailed descr iptions of each of the st eps in volved. Rememb er tha t only the st eps tha t are pertinen t to ac oustics mo deling ar e discussed her e. For inf ormation ab out the inputs r elated t o other mo dels that you ar e using in c onjunc tion with the FW-H ac oustics mo del, see the appr opriate sec tions f or those models . The gener al pr ocedur e for c arrying out an FW-H ac oustics c alcula tion in ANSY S Fluen t is as f ollows: 1.Calcula te a c onverged flo w solution. For a tr ansien t case, run the tr ansien t solution un til you obtain a “statistic ally st eady-sta te” solution as descr ibed b elow. 2.Enable the FW-H ac oustics mo del and set the asso ciated mo del par amet ers. Setup → Models → Acoustics Edit... 3.Specify the sour ce sur face(s) and cho ose the options asso ciated with acquisition and sa ving of the sour ce data. For a st eady-sta te case, specify the r otating sur face zone(s) as the sour ce sur face(s). 4.Specify the r eceiver lo cation(s). 5.Continue the tr ansien t solution f or a sufficien tly long p eriod of time and sa ve the sour ce da ta (tr ansien t cases only). Solution → Run C alcula tion 6.Comput e and sa ve the sound pr essur e signals . Solution → Run C alcula tion → Acoustic S ignals ... 7.Postpr ocess the sound pr essur e signals . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1878Predic ting A erodynamic ally G ener ated N oiseResults → Plots → FFT Edit... Imp ortant Before you star t the ac oustics c alcula tion f or a tr ansien t case, an ANSY S Fluen t transien t solution should ha ve been r un t o a p oint wher e the tr ansien t flo w field has b ecome “statist- ically st eady”. In pr actice, this means tha t the unst eady flo w field under c onsider ation, includ- ing all the major flo w variables , has b ecome fully de velop ed in such a w ay tha t its sta tistics do not change with time . Monit oring the major flo w variables a t selec ted p oints in the domain is helpful f or det ermining if this c ondition has b een met. As discussed ear lier, URANS, LES, and h ybrid R ANS-LES mo dels ar e all legitima te candida tes for tr ansien t flow calcula tions . For sta tionar y sour ce sur faces, the fr equenc y of the aer odynamic ally gener ated sound hear d at the r eceivers is lar gely det ermined b y the time sc ale or fr equenc y of the under lying flo w. Therefore, one w ay to det ermine the time-st ep siz e for the tr ansien t computa tion is t o mak e it small enough t o resolv e the smallest char acteristic time sc ale of the flo w at hand tha t can b e reproduced b y the mesh and turbulenc e adopt ed in y our mo del. Onc e you ha ve obtained a sta tistic ally sta tionar y flo w-field solution, you ar e ready to acquir e the sour ce data. For additional inf ormation, see the f ollowing sec tions: 23.2.1. Enabling the FW-H A coustics M odel 23.2.2. Specifying S ource Sur faces 23.2.3. Specifying A coustic R eceivers 23.2.4. Specifying the Time S tep 23.2.5. Postpr ocessing the FW-H A coustics M odel D ata 23.2.6. FFT of A coustic S ources: Band A naly sis and Exp ort of Sur face Pressur e Spectra 23.2.1. Enabling the FW-H A coustics M odel To enable the FW-H ac oustics mo del, selec t Ffowcs Williams & H awkings in the Acoustics M odel dialo g box (Figur e 23.1: The A coustics M odel D ialog Box (p.1880 )). Setup → Models → Acoustics Edit... When y ou selec t Ffowcs Williams & H awkings , the dialo g box will e xpand t o sho w the r elevant fields for user inputs . 1879Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the Ff owcs Williams and Ha wkings A coustics M odelFigur e 23.1: The A coustics M odel D ialo g Box 23.2.1.1. Setting Mo del C onstants Under Model C onstan ts in the Acoustics M odel dialo g box, specify the r elevant acoustic par amet ers and c onstan ts used b y the mo del. Far-F ield D ensit y (for e xample , in Equa tion 15.1 in the Theor y Guide ) is the far-field fluid densit y. Far-F ield S ound S peed (for e xample , in Equa tion 15.1 ) is the sound sp eed in the far field (= ). Free S tream Velocity and Free S tream D irection are requir ed when the c onvective eff ects ar e tak en in to acc oun t.They become a vailable in the in terface when Convective Effects is enabled . Imp ortant The use of Convective Effects with the pr oper Free S tream Velocity and Free S tream Direction is str ongly r ecommended f or all c ases dealing with e xternal flo ws around bodies . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1880Predic ting A erodynamic ally G ener ated N oiseReferenc e Acoustic P ressur e (for e xample , in Equa tion 40.41 (p.2905 )) is used t o calcula te the sound pr essur e level in dB (see Using the FFT U tility (p.2901 )).The default r eference ac oustic pr essur e is Pa. Numb er of Time S teps P er Re volution is available only f or st eady-sta te cases tha t ha ve a single mo ving r eference frame . Here you will sp ecify the numb er of equiv alen t time st eps tha t it will tak e for the r otating z one t o complet e one r evolution. Numb er of Re volutions is available only f or st eady-sta te cases tha t ha ve a single mo ving r eference frame . Here you will sp ecify the numb er of r evolutions tha t will b e simula ted in the mo del. Sour ce Correlation L ength is requir ed when sound is t o be comput ed using a 2D flo w result. The FW-H in tegrals will b e evalua ted over this length in the depth-wise dir ection using the iden tical sour ce da ta (see Figur e 23.2: The A coustics Model D ialog Box for a 3D S teady-State Case with a S ingle M oving R eference Frame (p.1882 )). The default v alues ar e appr opriate for sound pr opaga ting in air a t atmospher ic pr essur e and t emp er- ature. 23.2.1.2. Computing S ound “on the F ly” The FW-H ac oustics mo del in ANSY S Fluen t allo ws you t o perform simultaneous c alcula tion of the sound pr essur e signals a t the pr escr ibed r eceivers without ha ving t o wr ite the sour ce da ta to files , which c an sa ve a signific ant amoun t of disk spac e on y our machine .To enable this “on-the-fly ” calcu- lation of sound , enable the Comput e Acoustic S ignals S imultaneously option in the Acoustics Model dialo g box. Imp ortant Because the noise c omputa tion tak es a negligible p ercentage of memor y and c omputa- tional time c ompar ed t o a tr ansien t flo w calcula tion, this option c an b e used b y itself or along with the pr ocess of sour ce da ta file e xport and sound c alcula tion. For the la tter, computing signals “on the fly ” allo ws you t o see when the signals ha ve become sta tistic ally steady so y ou c an k now when t o stop the simula tion. When the Comput e Acoustic S ignals S imultaneously option is enabled , the ANSY S Fluen t console windo w will pr int a message a t the end of each time st ep indic ating tha t the sound pr essur e signals have been c omput ed (f or e xample ,Computing sound signals at x receiver loca- tions... , wher e x is the numb er of r eceivers y ou sp ecified). Enabling this option instr ucts ANSY S Fluen t to comput e sound pr essur e signals a t the end of each time st ep, which will sligh tly incr ease the c omputa tion time . Imp ortant Note tha t this option is a vailable only when the FW-H ac oustics mo del has b een enabled . See b elow for details ab out e xporting sour ce da ta without enabling the FW-H mo del. 1881Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the Ff owcs Williams and Ha wkings A coustics M odel23.2.1.3. Writing S our ce Data F iles Although the “on-the-fly ” capabilit y is a c onvenien t feature, you will w ant to sa ve the sour ce da ta as well, because the acquisition of sour ce da ta dur ing a tr ansien t flo w-field c alcula tion is the most time- consuming par t of ac oustics c omputa tions , and y ou most lik ely will not w ant to disc ard it. By sa ving the sour ce da ta, you c an alw ays reuse it t o comput e the sound pr essur e signals a t new or additional receiver lo cations . To sa ve the sour ce da ta to files , enable either the Export Acoustic S our ce D ata in ASD F ormat or the Export Acoustic S our ce D ata in C GNS F ormat option, or b oth. After y ou ha ve made y our selec tion, the r elevant sour ce da ta a t all fac e elemen ts of the selec ted sour ce sur faces will b e wr itten in to the files y ou sp ecify .The sour ce da ta v ary dep ending on the solv er option y ou ha ve chosen and whether the sour ce sur face is a w all or not. Table 23.1: Source Data S aved in S ource Data Files (p.1882 ) sho ws the flo w variables sa ved as the sour ce da ta. Figur e 23.2: The A coustics M odel D ialo g Box for a 3D S tead y-State Case with a S ingle M oving Referenc e Frame Table 23.1: Sour ce D ata S aved in S our ce D ata F iles Sour ce D ata Sour ce Surface Solver Option walls incompr essible permeable sur faces incompr essible walls compr essible permeable sur faces compr essible See Specifying S ource Sur faces (p.1884 ) for details on ho w to sp ecify par amet ers f or e xporting sour ce data. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1882Predic ting A erodynamic ally G ener ated N oise23.2.1.3.1. Exporting S our ce Data Without E nabling the FW -H Mo del: Using the ANSY S Fluent ASD F ormat You c an e xport sound sour ce da ta for use with SY SNOISE without ha ving t o enable the Ff owcs Wil- liams and Ha wkings (FW-H) mo del. You still must sp ecify sour ce sur faces (see Specifying S ource Surfaces (p.1884 )), as .index and .asd files ar e requir ed b y SY SNOISE . In addition, you c an cho ose fluid z ones as emission sour ces if y ou w ant to export quadr upole sour ces.To enable the selec tion of fluid z ones as sour ces, use the define → models → acoustics → export-volumetric-sources? text command and change the selec tion t o yes . SYSNOISE also r equir es c entroid da ta for sour ce zones tha t are being e xported. For fan noise c alcula tions , onc e you ha ve sp ecified the sour ce zones in the Acoustic S our ces dialo g box and y ou ha ve selec ted Export Acoustic S our ce D ata in ASD F ormat from the Acoustics Model dialo g box, you c an e xport geometr y in c ylindr ical coordina tes b y using the define → models → acoustics → cylindrical-export? text command and changing the selec tion t o yes . By default , ANSY S Fluen t exports sour ce zones for SY SNOISE in C artesian c oordina tes. You c an then e xport the c entroid da ta to a da ta file using the f ollowing t ext command: define → models → acoustics → write-centroid-info Since you will not b e using the FW-H mo del t o comput e signals , you will not need t o sp ecify an y acoustic mo del par amet ers or r eceiver lo cations . Also, you will not b e able t o enable the Comput e Acoustic S ignals S imultaneously option in the Acoustics M odel dialo g box, and Acoustic S ignals ... will not b e available in the Run C alcula tion task page and in the menu f or the Run C alcula tion Outline View it em. 23.2.1.3.2. Exporting S our ce Data Without E nabling the FW -H Mo del: Using the C GNS Format The sound sour ce da ta for non-p ermeable sur faces c an b e exported in the C GNS file f ormat (for Virtual Lab) without ha ving t o enable the Ff owcs Williams and Ha wkings (FW-H) mo del. Enable the Export Acoustic S our ce D ata in C GNS F ormat option in the Acoustics M odel dialo g box (Fig- ure 23.3: The A coustics M odel D ialog Box for Exp orting in C GNS F ormat (p.1884 )). Specify the sour ce surfaces in the Acoustics S our ces dialo g box (see Specifying S ource Sur faces (p.1884 )) wher e, by default , the Numb er of Time S teps p er F ile is set t o 1. Note The f ollowing limita tions cur rently e xist f or e xporting ac oustic sour ce da ta: •ANSY S Fluen t do es not supp ort exporting ac oustic sour ce da ta in C GNS f ormat for p olyhedr al meshes . •Source da ta cannot b e simultaneously e xported f or multiple diff erently r otating w alls. All walls must b e either non-r otating , or r otate with the same r ate around the same axis . 1883Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the Ff owcs Williams and Ha wkings A coustics M odelFigur e 23.3: The A coustics M odel D ialo g Box for E xporting in C GNS F ormat Virtual Lab r equir es a mesh da ta file (named _mesh.cgns ) and a solution da ta file (named _.cgns ).The str ing is a gener ic name , which y ou will specify in the File N ame in the Acoustics S our ces dialo g box.There is one single solution da ta file (.cgns ) per time le vel exported, which c ontains the sta tic pr essur e at the w all-fac e centroid lo cation. The .cgns files will b e stored in a dir ectory, which y ou sp ecify (named / ) in the File N ame . In addition, you c an e xport quadr upole sour ces da ta b y cho osing fluid z ones as emission sour ces. To enable the selec tion of fluid z ones as sour ces, use the t ext command: define → models → acoustics → export-volumetric-sources-cgns? When ask ed if y ou w ould lik e to Export volumetric sources? enter yes . Note tha t Virtual Lab r equir es v olumetr ic mesh da ta file (_Q_mesh.cgns ) and quadr upole solution da ta files (_Q_.cgns ).The .cgns file will b e stored in a similar w ay to tha t of dipole da ta e xport, in the dir ectory you sp ecified in the File N ame text en try box. 23.2.2. Specifying S our ce Surfaces In the Acoustics M odel dialo g box, click the Define S our ces... butt on t o op en the Acoustic S our ces dialo g box (Figur e 23.4: The A coustics M odel D ialog Box (p.1885 )). Here you will sp ecify the sour ce sur- face(s) t o be used in the ac oustics c alcula tion and the inputs asso ciated with sa ving sour ce da ta to files . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1884Predic ting A erodynamic ally G ener ated N oiseFigur e 23.4: The A coustics M odel D ialo g Box Under Sour ce Zones , you c an selec t multiple emission (sour ce) sur faces and the sur face Type tha t you c an selec t is not limit ed t o a wall.You c an also cho ose interior sur faces and sliding in terfaces (both sta tionar y and r otating) as sour ce sur faces. Imp ortant The abilit y to cho ose multiple sour ce sur faces is useful f or in vestiga ting the c ontributions from individual sour ce sur faces.The r esults based on the use of multiple sour ce sur faces are valid as long as ther e ar e negligible ac oustic in teractions among the sur faces.Therefore, some c aution should b e tak en when selec ting multiple sour ce sur faces. In cases wher e multiple sour ce sur faces ar e selec ted, no sour ce sur face ma y enclose an y of the other sour ce sur faces. Other wise , the sound pr essur e calcula ted based on the sour ce sur faces will not b e accur ate, as the c ontribution fr om the enclosed (inner) sour ce sur faces is o ver pr edic ted, sinc e the FW- H mo del is unable t o acc oun t for the shading of the sound fr om the inner sour ce sur faces b y the en- closur e sur face. If you sp ecify an y interior sur faces as sour ce sur faces, the in terior sur face must b e gener ated in ad vance (for e xample , in GAMBIT ) in such a w ay tha t the t wo cell z ones adjac ent to the sur face ha ve diff erent cell z one IDs . Further mor e, you must c orrectly sp ecify which of the t wo zones is o ccupied b y the quadr upole sour ces (in terior c ell z one). This will allo w ANSY S Fluen t to det ermine the dir ection in which the sound will pr opaga te.When y ou first a ttempt t o selec t a legitima te in terior sur face (tha t is, an in terior sur face ha ving t wo diff erent cell z ones on b oth sides) as a sour ce sur face, the Interior C ell Zone S elec tion D ialog Box (p.3378 ) (Figur e 23.5: The In terior C ell Z one S elec tion D ialog Box (p.1886 )) will 1885Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the Ff owcs Williams and Ha wkings A coustics M odelapp ear.You must then selec t the in terior c ell z ones fr om the t wo zones list ed under the Interior C ell Zone .Figur e 23.6: An In terior S ource Sur face (p.1886 ) sho ws an e xample of an in terior sour ce sur face. Figur e 23.5: The In terior C ell Z one S elec tion D ialo g Box Like gener al in terior sur faces, if the sour ce sur faces selec ted ar e sliding in terfaces, a dialo g box similar to Figur e 23.5: The In terior C ell Z one S elec tion D ialog Box (p.1886 ) will app ear tha t will sho w the t wo adjac ent cell z ones and y ou will b e ask ed t o sp ecify the z one tha t has the sound sour ces. Imp ortant When a p ermeable sur face (either in terior or sliding in terface) is chosen as the sour ce sur face, other w all sur faces inside the v olume enclosed b y the p ermeable sur face tha t gener ate sound should not b e chosen f or the ac oustics c alcula tion. For e xample , when r unning an “on-the-fly ” calcula tion, if b oth these sur faces ar e selec ted, the sound pr essur e will b e coun ted t wice. Figur e 23.6: An In terior S our ce Surface Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1886Predic ting A erodynamic ally G ener ated N oise23.2.2.1. Saving S our ce Data To sa ve the sour ce da ta, you ha ve to sp ecify the File N ame ,Write Frequenc y (in numb er of time steps), and Numb er of Time S teps p er F ile in the Acoustic S our ces dialo g box. The File N ame is used t o giv e the names of the sour ce da ta files (f or e xample ,acoustic_ex- amplexxxx.asd , wher e xxxx is the global time-st ep inde x of the tr ansien t solution) and an inde x file (f or e xample ,acoustic_example.index ) tha t will st ore the inf ormation asso ciated with the sour ce da ta.The Write Frequenc y allo ws you t o control ho w of ten the sour ce da ta will b e wr itten. This will enable y ou t o sa ve disk spac e if the time-st ep siz e used in the tr ansien t flo w simula tion is smaller than nec essar y to resolv e the sound fr equenc y you ar e attempting t o pr edic t. In most situa tions , however, you will w ant to sa ve the sour ce da ta a t every time st ep and use the default v alue of 1. Since ac oustics c alcula tions usually gener ate thousands of time st eps of sour ce da ta, you ma y want to split the da ta in to se veral files . Specifying the Numb er of Time S teps p er F ile allo ws you t o wr ite the sour ce da ta in to separ ate files f or diff erent simula tion in tervals, the dur ation of which (in t erms of the numb er of tr ansien t flo w time st eps) is sp ecified b y you. For e xample , if y ou sp ecify 100 f or this par amet er, each file will c ontain sour ce da ta for an in terval length of 100 time st eps r egar dless of the wr ite frequenc y. You will find this f eature useful if y ou w ant to use a selec ted numb er of sour ce da ta files t o comput e the sound pr essur e rather than using all the da ta. For e xample , you ma y want to exclude an initial portion of the sour ce da ta fr om y our ac oustics c alcula tion b ecause y ou ma y realiz e later tha t the flo w field has not fully a ttained a sta tistic ally st eady sta te. After y ou click Apply , ANSY S Fluen t will cr eate the inde x file (f or e xample ,acoustics_example.in- dex ), which c ontains inf ormation ab out the sour ce da ta. Imp ortant If you cho ose t o sa ve sour ce da ta, keep in mind tha t the sour ce da ta can use up a c onsid- erable amoun t of disk spac e, esp ecially if the mesh b eing used has a lar ge numb er of fac e elemen ts on the sour ce sur faces y ou selec ted. ANSY S Fluen t will pr int out the disk spac e requir emen t per time st ep a t the time of sour ce sur face selec tion if the Export Acoustic Sour ce D ata in ASD F ormat option is enabled in the Acoustics M odel dialo g box. At this p oint, if y ou ha ve chosen t o perform y our ac oustics c alcula tion in t wo steps, (tha t is, saving the sour ce da ta first , and c omputing the sound a t a la ter time), you c an go ahead and instr uct ANSY S Fluen t to perform a suitable numb er of time st eps, and the sour ce da ta will b e sa ved t o the disk. If you chose t o perform an “on-the-fly ” acoustic c alcula tion, then y ou must sp ecify r eceiver lo cations (see Specifying A coustic R eceivers (p.1887 )) before you r un the unst eady ANSY S Fluen t solution an y further . 23.2.3. Specifying A coustic Rec eivers In the Acoustics M odel dialo g box, click the Define Rec eivers... butt on t o op en the Acoustic Rec eivers dialo g box (Figur e 23.7: The A coustic R eceivers D ialog Box (p.1888 )). 1887Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the Ff owcs Williams and Ha wkings A coustics M odelFigur e 23.7: The A coustic Rec eivers D ialo g Box Imp ortant Note tha t you c an also op en the Acoustic Rec eivers dialo g box by click ing the Rec eivers... butt on in the Acoustic S our ces or the Acoustic S ignals dialo g box. If requir ed, you c an enable Moving Rec eivers to sp ecify the r eceiver motion. In this c ase, the defined Velocity magnitude and Direction apply t o all r eceivers.The r eceiver lo cations , defined b elow, are then in terpreted as the star ting lo cations a t the time tha t sound emission or igina tes.The or igina tion of sound emission is det ermined as f ollows: •For “on the F ly” use of the FW-H mo del (see Computing S ound “on the F ly” (p.1881 )) the sound emission time is c oun ted fr om the ph ysical time of ac tivation of the Comput e Acoustic S ignals S imultaneously option (see Figur e 23.1: The A coustics M odel D ialog Box (p.1880 )). •When the FW-H mo del r eads the pr eviously wr itten ac oustic sour ce da ta (see Reading U nsteady Acoustic S ource Data (p.1891 )), the sound emission time star ts fr om the ph ysical time asso ciated with the first selec ted sour ce da ta file . Imp ortant When using mo ving r eceivers, not e tha t if y ou star t from a diff erent sour ce da ta file , this r esults in diff erent receiver lo cations due t o the diff erent emission time or igin as- sociated with the diff erent sour ce da ta file . Increase the Numb er of Rec eivers to the t otal numb er of r eceivers f or which y ou w ant to comput e sound , and en ter the c oordina tes for each r eceiver in the X-C oord.,Y-C oord., and Z-Coord. fields . Note tha t because ANSY S Fluen t’s ac oustics mo del is ideally suit ed f or far-field noise pr edic tion, the receiver lo cations y ou define should b e at a r easonable distanc e from the sour ces of sound (tha t is, the selec ted sour ce sur faces).The r eceiver lo cations c an also fall outside of the c omputa tional domain. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1888Predic ting A erodynamic ally G ener ated N oiseFor each r eceiver, you c an sp ecify a file name in the Signal F ile N ame field .These files will b e used to store the sound pr essur e signals a t the c orresponding r eceivers. By default , the files will b e named receiver-1.ard ,receiver-2.ard , and so on. Onc e the r eceiver lo cations ha ve been defined , the setup f or y our ac oustic c alcula tion is c omplet e. 23.2.4. Specifying the Time S tep When using an implicit-in-time solution algor ithm (dual-time st epping), and dep ending on the ph ysical time st ep siz e and the most imp ortant time sc ales in the flo w, you c an wr ite the ac oustic sour ce da ta at every time st ep.You c an also c oarsen it in time b y a giv en fr equenc y fac tor.The highest p ossible frequenc y the ac oustic analy sis c an gener ate is based on the time st ep siz e of the c ollec ted ac oustic sour ce da ta. When using the Densit y-Based explicit solv er, with the Explicit Transien t Formula tion selec ted in the Solution M etho ds task page , the ph ysical time st ep must b e comput ed b y the solv er, based on the CFL c ondition (C ourant numb er). Due t o the p ossibly lar ge fluc tuations of the ph ysical time st ep, an adapting time-st epping pr ocedur e can b e used when the FW-H ac oustics mo del is enabled .This allows you t o use a user-sp ecified time in terval for sampling the ac oustic da ta. In tur n, the solv er adapts its time st ep, when nec essar y, without viola ting the CFL c onditions t o mak e sur e tha t da ta is a vailable at the desir ed time in terval (henc e, avoiding da ta in terpolations). In the Run C alcula tion task page ( Figur e 23.8: The R un C alcula tion Task P age (p.1890 )), enter the Time Step S ize for A coustic D ata E xport to sp ecify the time in terval for ac oustic da ta sampling .The v alue of this c onstan t time st ep siz e det ermines the highest fr equenc y tha t the ac oustic analy sis r eproduces. You c an r efer to Performing Time-D ependen t Calcula tions (p.2626 ) for mor e inf ormation ab out the Run Calcula tion task page . Solution → Run C alcula tion 1889Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the Ff owcs Williams and Ha wkings A coustics M odelFigur e 23.8: The R un C alcula tion Task P age You c an no w pr oceed t o instr uct ANSY S Fluen t to perform a tr ansien t calcula tion f or a suitable numb er of time st eps.When the c alcula tion is finished , you will ha ve either the sour ce da ta sa ved on files (if you chose t o sa ve it t o a file or files), or the sound pr essur e signals (if y ou chose t o perform an acoustic c alcula tion “on the fly ”), or b oth (if y ou chose t o sa ve the sour ce da ta to files and if y ou chose to perform the ac oustic c alcula tion “on the fly ”). If you chose t o sa ve the sour ce da ta to files , the ANSY S Fluen t console will pr int a message a t the end of each time st ep indic ating tha t sour ce da ta ha ve been wr itten (or app ended t o) a file (f or e xample , acoustic_example240.asd ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1890Predic ting A erodynamic ally G ener ated N oise23.2.5. Postpr ocessing the FW-H A coustics M odel D ata At this p oint, you will ha ve either the sour ce da ta sa ved t o files or the sound pr essur e signals c omput ed, or b oth. You c an pr ocess these da ta to comput e and plot v arious ac oustic quan tities using ANSY S Fluen t’s FFT c apabilities . See Fast F ourier Transf orm (FFT ) Postpr ocessing (p.2898 ) for mor e inf ormation. 23.2.5.1. Writing A coustic S ignals If you chose t o perform the ac oustic c alcula tion “on the fly ”, you must wr ite the sound pr essur e da ta to files .To do so , selec t Write Acoustic S ignals under Options in the Acoustic S ignals dialo g box (Figur e 23.9: The A coustic S ignals D ialog Box (p.1892 )) and then click Write.The c omput ed ac oustic pressur e will b e sa ved fr om in ternal buff er memor y into a separ ate file f or each r eceiver y ou defined in the Acoustic Rec eivers dialo g box (for e xample ,receiver-1.ard ). Solution → Run C alcula tion → Acoustic S ignals ... 23.2.5.2. Reading Unst eady A coustic S our ce Data Computing the sound pr essur e signals using the sour ce da ta sa ved t o files is done in the Acoustic Signals dialo g box (Figur e 23.9: The A coustic S ignals D ialog Box (p.1892 )) Solution → Run C alcula tion → Acoustic S ignals ... 1891Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the Ff owcs Williams and Ha wkings A coustics M odelFigur e 23.9: The A coustic S ignals D ialo g Box To comput e the sound da ta, use the f ollowing pr ocedur e: 1.In the Acoustic S ignals dialo g box, selec t Read U nstead y Acoustic S our ce Data F iles under Options . 2.Click Load Inde x File... and selec t the inde x file f or y our c omputa tion in the Selec t File dialo g box.The file will ha ve the name y ou en tered in the File N ame field in the Acoustic S our ces dialo g box, followed by the .index suffix (f or e xample ,acoustic_example.index ). 3.In the Sour ce Data F iles list, selec t the sour ce da ta files tha t you w ant to use t o comput e sound . Source data files will all c ontain the sp ecified r oot file name f ollowed b y the suffix .asd . Imp ortant You c an use an y numb er of sour ce da ta files . However, not e tha t you should selec t only c onsecutiv e files . 4.In the Active Sour ce Zones list, selec t the sour ce zones y ou w ant to include t o comput e sound . See Specifying S ource Sur faces (p.1884 ) for details ab out pr oper sour ce sur face selec tion. 5.In the Rec eivers list, selec t the r eceivers f or which y ou w ant to comput e and sa ve sound . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1892Predic ting A erodynamic ally G ener ated N oiseOptionally , you c an click the Rec eivers... butt on t o op en the Acoustic Rec eivers dialo g box and define additional r eceivers. 6.Click the Comput e/W rite butt on t o comput e and sa ve the sound pr essur e da ta. One file will b e sa ved for each r eceiver you pr eviously sp ecified in the Acoustic Rec eivers dialo g box (for e xample ,receiver- 1.ard ). Imp ortant If you enabled b oth the Export Acoustic S our ce D ata in ASD F ormat and Comput e Acoustic S ignals S imultaneously options in the Acoustics M odel dialo g box, you must first selec t the Write Acoustic S ignals option in the Acoustic S ignals dialo g box after the flow simula tion has b een c omplet ed. If you selec t the Read U nstead y Acoustic S our ce Data F iles before wr iting out the “on-the-fly ” data in such a c ase, the da ta will b e flushed out of the in ternal buff er memor y.To avoid such a loss of da ta, you should sa ve the ANSY S Fluen t case and da ta files whene ver y ou b egin t o do an ac oustic c omputa tion in the Acoustic S ignals dialo g box.The sound pr essur e da ta calcula ted “on the fly ” will then b e saved in to the .dat file. Finally , after the “on-the-fly ” data is sa ved, mak e sur e to change the file names of the r eceivers b efore doing a sound pr essur e calcula tion with the Read Unstead y Acoustic S our ce D ata F iles option enabled , to avoid o verwriting the “on-the- fly” signal files . Imp ortant Note tha t you c an c omput e and wr ite sound pr essur e signals only when the FW-H ac oustics model has b een enabled . See Exporting S ource Data Without Enabling the FW-H M odel: Using the ANSY S Fluen t ASD F ormat (p.1883 ) for details ab out e xporting sour ce da ta (f or example , for SY SNOISE) without enabling the FW-H mo del. 23.2.5.2.1. Pruning the S ignal D ata A utomatic ally Before the c omput ed sound pr essur e da ta a t each r eceiver is sa ved, it is b y default aut oma tically pruned . Pruning of the r eceiver da ta means clipping the tails of the signal wher e inc omplet e sour ce information is a vailable . The ac oustic sour ce da ta is tabula ted fr om time to .Without aut o-pr uning , the r eceiver regist er begins r eceiving the ear liest sound pr essur e signal a t (23.1) wher e is the shor test distanc e between the sour ce sur faces and the r eceiver. However, the r e- ceiver will not r eceive the sound pr essur e signal fr om the far thest p oint on the sour ce sur faces ( ) until the r eceiver time b ecomes (23.2) From time to , the sound accumula ted on the r eceiver regist er do es not include the c ontribution from the en tire sour ce sur face ar ea, and ther efore the sound pr essur e da ta received dur ing tha t time is not c omplet e.The same thing o ccurs dur ing the p eriod from (23.3) 1893Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the Ff owcs Williams and Ha wkings A coustics M odelto (23.4) Therefore, pruning means clipping the signal on the inc omplet e ends , from to and to . Auto-pr uning c an b e disabled using the define → models → acoustics → auto-prune text command . Although aut o-pr uning c an b e disabled , it is e xpected tha t you will use only the c omplet e sound pr essur e da ta. 23.2.5.3. Reporting the Static P ressur e Time D eriv ativ e The RMS v alue of the sta tic pr essur e time der ivative ( ) is a vailable f or p ostpr ocessing only on wall sur faces, which ar e at the same time sour ces of sound , when the FW-H ac oustics mo del is used . You c an selec t Surface dp dt RMS in the Acoustics ... categor y only when y ou sp ecify a t least one wall sur face, which is also mar ked as an ac oustic sour ce, in the r elevant postpr ocessing dialo g boxes. 23.2.5.4. Using the FFT C apabilities for S ound P ressur e Signals Onc e the sound pr essur e signals ar e comput ed and sa ved in files , the sound da ta is r eady to be analyz ed using ANSY S Fluen t’s FFT t ools. In the Four ier Transf orm dialo g box (Figur e 40.84: The Fourier Transf orm D ialog Box (p.2901 )), click Load Input F ile... and selec t the appr opriate .ard file. If the r eceiver da ta is still in ANSY S Fluen t’s memor y, then it c an dir ectly b e pr ocessed using the Process Rec eiver option. See Fast F ourier Transf orm (FFT ) Postpr ocessing (p.2898 ) for mor e inf ormation on ANSY S Fluen t’s FFT c apabilities . Results → Plots → FFT Edit... 23.2.6. FFT of A coustic S our ces: Band A naly sis and E xport of S urface Pressur e Spectra During a tr ansien t flo w simula tion, the time hist ories of the instan t sur face pr essur e values c an b e written in to the binar y ac oustic sour ce da ta (ASD) files .This op eration is p erformed f or all mesh c ell faces of those sur face zones tha t are selec ted as ac oustic sour ces.The pr imar y pur pose of the ASD files is t o supply input da ta for the Ff owcs Williams and Ha wkings ac oustic solv er (see Reading U nsteady Acoustic S ource Data (p.1891 )). Additionally , these files c an b e used t o visualiz e the sp ectral pr operties of the st ored flo w pr essur e signals .The supp orted sp ectral pr operties ar e the c omple x amplitudes f or the individual F ourier mo des, and the sur face pr essur e level (SPL) v alues f or the fr equenc y bands , in decib els. Both the c onstan t width and the pr oportional width bands (o ctaves and 1/3 o ctaves) c an b e specified . Note Despit e the use of the c ommon acr onym “SPL”, the c alcula ted v alues char acterize the transien t flo w pr essur e on a sur face, and not the ac oustic pr essur e; tha t is, in this c ontext, the acr onym r efers t o the “Surface Pressur e Level” (as men tioned pr eviously) and not the “Sound P ressur e Level”. In addition t o the visualiza tion c apabilities , with ANSY S Fluen t you c an also use the ASD files t o export the c omput ed sp ectrum fields of the flo w pr essur e as C GNS files .The pr imar y pur pose of such files is Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1894Predic ting A erodynamic ally G ener ated N oiseto allo w you t o use the sur face sp ectrum fields as distr ibut ed e xcitation f orces when p erforming a harmonic r esponse analy sis with ANSY S M echanic al.The abilit y to imp ort CGNS files is a vailable in ANSY S M echanic al to ma tch this e xport feature in F luen t; for details , see FLUREAD in the separ ate Mechanic al APDL Command R eferenc e. Using the ac oustic w ave equa tion solv er of ANSY S M echanic al, it is p ossible t o perform fr equenc y domain simula tions f or applic ations such as the v ehicle c abin noise caused b y external turbulen t flo w. 23.2.6.1. Using the FFT of A coustic S our ces The Acoustic S our ces FFT… butt on is a vailable in the Run C alcula tion task page under the f ollowing conditions: •The simula tion is set up as a thr ee-dimensional tr ansien t case. •The Export Acoustic S our ce Data in ASD F ormat option is enabled in the Acoustics M odel dialo g box. Clicking the Acoustic S our ces FFT… butt on op ens the Acoustic S our ces FFT dialo g box, which has four tabs (each of which is sho wn in the figur es tha t follow): •Read ASD F iles •Comput e FFT F ields •FFT S urface Variables •Write CGNS F iles The first t wo tabs ar e obliga tory, because the ac tions p erformed ther e pr epar e the F ourier sp ectra for the ac tions tha t follow, including cr eation of the sur face variables t o visualiz e (p erformed in the third tab) and/or C GNS e xport (performed in the f ourth tab). Postpr ocessing b egins in the Read ASD F iles tab .The Active Sour ce Zones selec tion list sho ws all of the fac e zones f or which tr ansien t export to ASD files has b een p erformed (see Figur e 23.10: The Read ASD F iles Tab of the A coustic S ource FFT D ialog Box (p.1896 )).The Sour ce D ata F iles selec tion list sho ws all of the a vailable ASD files . Note tha t you c an up date this inf ormation b y click ing the Load Inde x File… butt on and sp ecifying the name of the inde x file t o be read; the inde x file w as created dur ing the ASD files e xport, and is an ASCII file c ontaining a list of the sour ce zones and a list of the ASD file names . Selec t in the selec tion lists the desir ed fac e zones as w ell as the desir ed ASD files fr om which y ou w ant to read, and click the Read butt on.The c onsole displa ys inf ormation about the da ta, such as the f ollowing e xample: Overall 10000 timesteps have been read from 3.0001 s to 4 s Time step is 0.0001 s 1895Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the Ff owcs Williams and Ha wkings A coustics M odelFigur e 23.10: The Read ASD F iles Tab of the A coustic S our ce FFT D ialo g Box Having r ead the pr essur e hist ories, open the Comput e FFT F ields tab ( Figur e 23.11: The C omput e FFT F ields Tab of the A coustic S ource FFT D ialog Box (p.1897 )).The v alues sho wn in the Spectral Resolution group b ox pr ovide inf ormation ab out the sta tistic al pr operties, which dep end on the sampling r ate (tha t is, the simula tion time st ep) and the signal length (tha t is, the simula tion time). These v alues will change if y ou enable the Clip Time t o Range option in the Sampling D ata group box, reduc e the time r ange f or the signals b y changing the Min and/or Max fields , and click the Re- Estima te Spectral Resolution butt on.The Windo w F unc tion selec tion list allo ws you t o sp ecify a windo w func tion using the same choic es tha t are available f or plotting the single signal FFT in the Plot/M odify Input S ignal dialo g box.The default settings use the full signals and the Hanning windo w func tion. The FFT c alcula tion b egins when y ou click the Comput e butt on. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1896Predic ting A erodynamic ally G ener ated N oiseFigur e 23.11: The C omput e FFT F ields Tab of the A coustic S our ce FFT D ialo g Box The fields of the pr essur e hist ories and the c omput ed fields of the F ourier sp ectra ar e stored in a large memor y ar ray, referred t o her e as the “storage ar ea”.This memor y is allo cated b y Fluen t dynam- ically when y ou r ead the pr essur e signals fr om the ASD files . If you r ead da ta for all fac e zones a vailable in the ASD files , and if the y are the w all z ones , then the siz e of the allo cated st orage ar ea is equal t o the t otal siz e of the ASD files b eing r ead. Since the same or a sligh tly smaller amoun t of da ta is pr o- duced b y the FFT algor ithm, the same st orage ar ea c an b e re-used t o store the F ourier sp ectra without allocating additional memor y. Alternatively, the pr essur e hist ories c an b e lef t intact in memor y, and for their sp ectra the st orage ar ea is c orrespondingly incr eased . These t wo mo des of memor y allo cation ar e controlled b y the Overwrite Signals b y Spectra option in the Storage A rea C ontrol group b ox.When the Overwrite Signals b y Spectra option is enabled , the F ourier sp ectra displac e in memor y the or iginal time signals , which ar e not k ept af ter the FFT has been c omput ed.Therefore, if y ou w ant to re-comput e the FFT using the Clip Time t o Range tool or a diff erent Windo w F unc tion (which ar e both in the Comput e FFT F ields tab), you ha ve to first de- allocate the st orage ar ea b y click ing the Clean U p Entire Storage A rea butt on, and then r e-read the pressur e hist ories fr om the ASD files .When the Overwrite Signals b y Spectra option is disabled , you c an r e-comput e the FFT without r e-reading the pr essur e hist ories, as man y times as y ou w ant. To do this , click the Clean U p Only FFT Results butt on, and pr oceed with c omputing sp ectra from the a vailable pr essur e hist ories. De-allo cation of the st orage ar ea (which c an b e very lar ge) is r ecom- mended when y ou ar e done using the Acoustic S our ces FFT dialo g box and plan t o either pr oceed to other p ostpr ocessing w ork or c ontinue y our tr ansien t simula tion without r e-star ting F luen t. When the pr essur e hist ories ar e read and k ept in the st orage ar ea, you c an cr eate point probes within the sur face zones tha t ha ve been r ead and e xtract the single pr essur e time signals a t these probes.The e xtracted signals and their sp ectra ma y help t o analyz e the tr ansien t flo w pr operties. For example , by creating an X Y plot of a signal, you c an figur e out the need f or clipping of the sampling time; by creating an X Y plot of its sp ectrum, you c an det ect the pr esenc e of the t onal noise c omp on- ents. To cr eate a p oint probe, open the Point Sur face Dialog Box (p.3898 ) by click ing Create and selec ting Point... in the Domain ribbon tab ( Surface group b ox), and cr eate a p oint sur face by an y available 1897Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the Ff owcs Williams and Ha wkings A coustics M odelmetho d (for e xample , by sp ecifying the c oordina tes).The p oint probe will b e created a t the fac e center tha t is near est t o the p oint sur face on the r ead sur face zones .The cr eated p oint probes ar e then list ed under the p oint sur face names in the Existing P oints selec tion list , which is lo cated in the Point Probes f or Time S ignals group b ox.You c an pr int the c oordina tes of the p oint probes to the F luen t console b y selec ting the desir ed pr obes and click ing the Print Coordina tes butt on. Clicking the Extract Signals butt on outputs the pr essur e hist ories f or the selec ted pr obes in the ASCII files; these files c an then b e analyz ed using the Fourier Transf orm D ialog Box (p.3712 ) (available fr om the Plots Task P age (p.3702 )) by selec ting Process F ile D ata and then r eading the e xported ASCII file using the Load Input F ile... butt on.The e xported files names ar e by default the p oint probe names with the e xtension .dat .The File N ame field allo ws you t o sp ecify a pr efix f or these file names . The FFT S urface Variables tab is sho wn in Figur e 23.12: The FFT Sur face Variables Tab of the A coustic Source FFT D ialog Box for the O ctave Bands (p.1898 ) and Figur e 23.14: The FFT Sur face Variables Tab of the A coustic S ource FFT D ialog Box for a S et of Individual M odes (p.1900 ).This tab allo ws you t o Create new F luen t variables using the c omput ed sp ectrum fields , which r eside in the st orage ar ea and c orrespondingly incr ease its siz e.These v ariables will b e defined only on those w all fac e zones for which the F ourier tr ansf ormation has b een c omput ed; on the other fac e zones , the y will sho w zero values . Created v ariables c an b e used f or an y kind of fur ther p ostpr ocessing in F luen t, which typic ally includes c ontour plotting (see the v ariables mar ked with the r estriction asff t in Table 42.17: Acoustics Categor y (p.2987 )) or e xporting t o CFD-P ost. Figur e 23.12: The FFT S urface Variables Tab of the A coustic S our ce FFT D ialo g Box for the O ctave Bands Variables ma y char acterize either the individual F ourier mo des (if y ou selec t Set of M odes from the Modes/F requenc y Bands drop-do wn list), or fr equenc y bands tha t each r epresen t a r ange of fr equen- cies (if y ou selec t the other choic es in the Modes/F requenc y Bands drop-do wn list). The thr ee t ypes of fr equenc y bands tha t are available include: •Octave Bands These ar e pr oportional bands c orresponding t o the standar d technic al octaves. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1898Predic ting A erodynamic ally G ener ated N oise•1/3 O ctave Bands These ar e pr oportional bands c orresponding t o the standar d technic al thir ds. •Constan t Width B ands These ar e user-defined equidistan t bands . The Spectrum P roperty drop-do wn list displa ys the t ype of v ariables cr eated acc ording t o the selec ted choic e in the Modes/F requenc y Bands drop-do wn list. For a set of mo des, the cr eated v ariables ar e the r eal and the imaginar y par ts of the c omple x Fourier amplitudes , with a pair of v ariables p er sp ecified mode. For the fr equenc y bands , the cr eated v ariables ar e the sur face pr essur e level (SPL) fields , in decib els.The tr ansf ormation t o the decib el units is done b y default using the standar d ac oustic r efer- ence pr essur e value of 2 x 10-5 Pa; you c an change this v alue b efore creating the v ariables b y op ening the Acoustic M odels dialo g box, selec ting the Ffowcs Williams & H awkings mo del, and r evising the Referenc e Acoustic P ressur e. For an y type of fr equenc y band (o ctave, 1/3, or c onstan t width), the ar ea-a veraged band-sp ecific pressur e fluc tuations ar e calcula ted and pr inted out t o the F luen t console in decib els when y ou click Create. Conversion t o decib els is done af ter the ar ea-a veraging of the band-filt ered RMS pr essur e fluctuation fields .The ar ea-a veraged da ta is pr inted only f or those fr equenc y bands tha t are covered by the r esulting pr essur e sp ectrum. If you enable the Write Area-A vg D ata option and sp ecify a file name in the c orresponding field , then the ar ea-a veraged da ta will b e wr itten t o an ASCII file in the XY plot file f ormat (see XY Plot F ile F ormat (p.2874 )). It is r ecommended tha t you use the file name extension .xy to mor e easily r ecogniz e this file when using the X Y plotting t ool. If you enable the Plot A rea-A vg D ata option, then the da ta will b e plott ed in the f orm of a bar char t in the gr aphics windo w when y ou click Create, as sho wn in Figur e 23.13: Bar C hart of Sur face Pressur e Level for O ctave Bands (p.1899 ). Figur e 23.13: Bar C har t of S urface Pressur e Level for O ctave Bands 1899Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the Ff owcs Williams and Ha wkings A coustics M odelFigur e 23.14: The FFT S urface Variables Tab of the A coustic S our ce FFT D ialo g Box for a S et of Individual M odes The allo wed numb er of v ariables mak es it p ossible f or y ou t o simultaneously k eep SPL f or all o ctave and 1/3 o ctave bands , as w ell as SPL f or up t o 20 c onstan t width bands and the r eal and imaginar y amplitudes f or up t o 20 individual fr equencies .The SPL v ariables f or the o ctaves and the 1/3 o ctaves include the band c entral fr equenc y in their names (f or e xample ,SPL f or O ctave Band a t 250Hz (dB) or SPL f or 1/3-O ctave Band a t 1.25kHz (dB) ). As for the user-defined fr equencies and c onstan t width bands , their v ariables ar e simply numb ered fr om 0 t o 19. In or der t o pr ovide y ou with the inf ormation about the meaning of each such v ariable , Fluen t prints a table in the c onsole when y ou click Create. The f ollowing is an e xample of the table c orresponding t o the settings in the pr evious figur e: Creating variables for 20 modes from 40.5983 Hz to 466.88 Hz every 22.4359 Hz. f( 0) = 40.5983 Hz f( 1) = 63.0342 Hz f( 2) = 85.4701 Hz f( 3) = 107.906 Hz f( 4) = 130.342 Hz f( 5) = 152.778 Hz f( 6) = 175.214 Hz f( 7) = 197.65 Hz f( 8) = 220.085 Hz f( 9) = 242.521 Hz f(10) = 264.957 Hz f(11) = 287.393 Hz f(12) = 309.829 Hz f(13) = 332.265 Hz f(14) = 354.701 Hz f(15) = 377.137 Hz f(16) = 399.573 Hz f(17) = 422.009 Hz f(18) = 444.444 Hz f(19) = 466.88 Hz Variables for frequencies above 466.88 Hz are not created, because the limit of 20 modes has been reached. You c an analyz e mor e than 20 individual mo des or c onstan t width bands , if y ou pr ocess them b y portions of 20 it ems and delet e the pr ocessed v ariables b y selec ting them in the Existing Variables list and click ing the Remo ve Selec ted Variables butt on. Clicking either the Clean U p Entire Storage A rea or the Clean U p Only FFT Results butt on on the left side of the dialo g box not only de-allo cates the sp ectrum st orage ar ray, but also r emo ves all created v ariables . The Write CGNS F iles tab is sho wn in Figur e 23.15: The Write CGNS F iles Tab of the A coustic S ource FFT D ialog Box (p.1901 ).This tab allo ws you t o sp ecify the z ones y ou w ant to export to CGNS, by se- Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1900Predic ting A erodynamic ally G ener ated N oiselecting them in the Processed S our ce Zones list. You c an r educ e the e xported sp ectrum da ta b y enabling the Reduc e Frequenc y Series option and sp ecifying the fr equenc y range ( Min and Max frequencies), as w ell as the fr equenc y step (the Numb er of F requencies t o Skip integer field). The latter must b e used with c are and only if r eally needed , because the F ourier amplitudes in the broadband noise sp ectrum dep end on the fr equenc y resolution. By sk ipping fr equencies fr om the exported sp ectrum (f or e xample , exporting e very other F ourier mo de), you will ar tificially c oarsen the frequenc y resolution. However, the e xported amplitudes will not b e aut oma tically r e-sc aled f or the increased fr equenc y step, but will r etain their or iginally c omput ed v alues . Pressur e sp ectra, which r esult fr om the sc ale-r esolving flo w simula tions , ma y contain thousands of frequencies .Together with dense sur face meshes , this c an r esult in a v ery lar ge amoun t of da ta to export.The t otal siz e of the disk spac e requir ed t o store fields of the c omplet e sp ectra is appr oxima tely equal t o the t otal siz e of the ASD files c ontaining the w all pr essur e hist ories.Therefore, the w all pressur e sp ectra ar e wr itten t o a ser ies of C GNS files acc ording t o the Numb er of F requencies p er File field . It is r ecommended tha t you selec t an appr opriate value f or this par amet er, to avoid e xtremely large output files or a lar ge numb er of v ery small files .The t otal numb er of fr equencies in the sp ectrum can b e seen in the Numb er of M odes field of the Comput e FFT F ields tab (see Figur e 23.11: The Comput e FFT F ields Tab of the A coustic S ource FFT D ialog Box (p.1897 )). Figur e 23.15: The Write CGNS F iles Tab of the A coustic S our ce FFT D ialo g Box Finally , you c an sp ecify a name f or the e xported C GNS files in the File N ame field . For e xample , if you en ter wall_pressure_spectrum and then click the Write butt on, Fluen t will cr eate the f ol- lowing set of files in y our w orking f older : wall_pr essur e_sp ectrum.cgns wall_pr essur e_sp ectrum_1.cgns wall_pr essur e_sp ectrum_2.cgns ... wall_pr essur e_sp ectrum.flst 1901Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the Ff owcs Williams and Ha wkings A coustics M odelIf you lea ve the File N ame field empt y, the files will b e named cgns ,1.cgns ,2.cgns ,...,flst.The first CGNS file (without a numb er in its name) c ontains the mesh da ta, as w ell as links t o all of the other CGNS files , which in tur n contain the sp ectrum fields with the sp ecified numb er of mo des p er file . The C GNS links w ork lik e the file links in the UNIX file sy stem: in or der t o imp ort sp ectra to the ANSY S Mechanic al sof tware, you only ha ve to sp ecify the name of the first file , and all other files will b e im- ported aut oma tically if the y reside in the same f older .The file with the e xtension flst is an ASCII file , which c ontains the list of the e xported fr equencies . Imp ortant Note the f ollowing: •You should not sp ecify a r elative pa th as a par t of the File N ame input. If you do tha t, all files will b e exported in the desir ed f older acc ording t o the sp ecified pa th. However, the C GNS links , which ar e wr itten in the first C GNS file , will also include the sp ecified pa th.Therefore, the link ed CGNS files will b ecome r eadable only af ter the c orresponden t file r elocation—f or e xample , moving the first C GNS file in y our F luen t working f older . •The public domain C GNS libr ary, which is used t o pr ocess C GNS files in F luen t and ANSY S Mechanic al, has a p erformanc e issue when r un on Windo ws. Namely , for C GNS files tha t ha ve man y links (as is the c ase in this applic ation), the input / output op erations ma y be very slo w if the C GNS files ar e located on a net work disk. Therefore, for Windo ws it is str ongly r ecommen- ded tha t you selec t either a built-in lo cal disk or a USB disk dir ectly c onnec ted t o your c omput er as the lo cation of the C GNS files .This w arning c oncerns b oth the e xport of C GNS files fr om Fluen t and their imp ort in ANSY S Mechanic al. 23.3. Using the A coustics Wave Equa tion M odel The ac oustics w ave equa tion mo del is r ecommended t o be used with sc ale-r esolving simula tions of turbulen t flo ws at low M ach numb ers (LES, SBES, DES, SAS). Due t o the cur rent limita tion of c onstan t densit y and sound sp eed in the back ground fluid flo w, no signific ant variation of these t wo par amet ers due t o non-unif orm temp erature or mix ture comp osition is allo wed. It is highly r ecommended tha t you r ead Preventing N on-P hysical Reflec tions of S ound Waves in the Fluent Theor y Guide for str ategies t o impr ove simula tion qualit y. The w ave equa tion mo del is a vailable f or tr ansien t flo w simula tions with the sec ond or der or b ounded second or der implicit time scheme ac tive.The mo del is not a vailable f or the 2-D axisymmetr ic version of F luen t. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1902Predic ting A erodynamic ally G ener ated N oiseFigur e 23.16: The A coustics M odel D ialo g Box You c an enable the Wave Equa tion using the TUI c ommand: /define/models/acoustics/wave-equation? The w ave equa tion options ar e found in the menu: /define/models/acoustics/wave-equation-options The field Artificial Visc osit y Factor f or S ponge L ayer is used t o sp ecify par amet er C, which par ticipa tes in Equa tion 15.13 .The base le vel of ar tificial visc osity can b e changed b y the TUI c ommand: /define/models/acoustics/wave-equation-options/sponge-layer-base-level The far-field par amet ers c an b e set using the TUI c ommand: /define/models/acoustics/far-field-parameters 23.3.1. Specifying S our ce M ask and S ponge Regions The Acoustics Region group b ox is used t o set up the geometr y of the sour ce mask and sp onge r egions . 1903Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the A coustics Wave Equa tion M odelThere ar e two metho ds t o define geometr y da ta: •Prepar ing UDFs •Use of basic shap es (r ectangular he xahedr on, cylinder , spher e) The t wo metho ds ma y be combined t ogether .The sour ce mask and the sp onge la yer UDFs ar e created using the f ollowing macr os: DEFINE_SOURCE_MASK(src_mask_define, c, t) DEFINE_SPONGE_LAYER(sponge_define, c, t) wher e src_mask_define and sponge_define are example func tion names ,c is a c ell numb er, and t is a p ointer to a c ell thr ead.There can only b e one UDF of each of these t wo types p er simula tion. Each UDF r etur ns a single r eal v alue , which fills a c orresponding st orage v ariable (SV_SOUND_MOD- EL_SRC_MASK or SV_SOUND_SPONGE ) in the c ell c of the thr ead t. Simple geometr ies c an b e built out of the basic shap es (r ectangular he xahedr on, cylinder , spher e), which must b e pr eliminar ily defined as c ell r egist ers of the t ype Region . Imp ortant The c ell r egist ers must b e created using the Outline View path ( Solution → Cell Re- gist ers New → Region.. ) and not the r ibbon pa th ( → Domain → Adapt → Mark/A dapt C ells → Region... , which is only a vailable if y ou ha ve used the f ollowing t ext command:mesh/adapt/revert-to-R19.2-user-interface ). The la tter pa th cr eates older st yle r egist ers tha t cannot b e used f or sour ce mask and sp onge geometr y definitions .The appr opriate TUI c ommands t o cr eate and edit c ell r egist ers ar e located in the menu /solve/cell-registers . After y ou cr eate one or mor e cell r egist ers, you c an use them t o sp ecify the desir ed geometr y by click ing Basic S hap es... in the Acoustics M odel dialo g box (Figur e 23.16: The A coustics M odel D ialog Box (p.1903 )), which op ens the Basic S hap es dialo g box (Figur e 23.17: The B asic S hap es D ialog Box (p.1905 )). In this windo w you c an add c ell r egist ers t o either the sour ce mask or sp onge la yer geo- metr y definitions , and sp ecify the individual tr ansition thick ness f or each shap e for each pur pose. Note After the c ell r egist ers ha ve been used f or the sour ce mask and sp onge la yer geometr y definitions , subsequen t editing or deleting of these c ell r egist ers do not influenc e the alr eady specified sour ce mask and sp onge la yer geometr y. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1904Predic ting A erodynamic ally G ener ated N oiseFigur e 23.17: The B asic S hap es D ialo g Box The TUI c ommands f or cr eating and editing sour ce mask and sp onge la ter geometr y can b e found in the menu: /define/models/acoustics/wave-equation-options/basic-shapes/ To visualiz e the sour ce mask and the sp onge la yer geometr ies, use the field v ariables Sound WaveEq Model Source Mask and Sound Sponge Layer Marker from the Acoustics… variable gr oup . These output fields dir ectly sho w the st orage v ariables SV_SOUND_MODEL_SRC_MASK and SV_SOUND_SPONGE without an y transf ormations . 23.3.2. Solution C ontrols f or the A coustics Wave Equa tion When the w ave equa tion mo del is ac tive, the Solution C ontrols task page includes an additional frame titled Acoustics Wave Equa tion S olver C ontrols (see Figur e 23.18: The A coustics Wave Equa tion Solver C ontrols Task P age (p.1906 )). 1905Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the A coustics Wave Equa tion M odelFigur e 23.18: The A coustics Wave Equa tion S olver C ontrols Task P age The par amet ers Rela tive Convergenc e Criterion and Max I terations/T ime S tep control the sub-it er- ations of the implicit w ave equa tion solv er.The need f or sub-it erations c omes fr om e xplicit sk ewness corrections t o the discr etiza tion of the basic Laplacian t erm in Equa tion 15.11 , as w ell as the ar tificial Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1906Predic ting A erodynamic ally G ener ated N oiseviscosity term. At each sub-it eration, the sy stem of linear equa tions is pr ocessed b y the AMG linear solv er to reduc e the r esidual nor m b y a fac tor of 0.1 (this c an b e controlled b y changing the r p-variable acoustics-waveeq/amg-alpha ).The optimal v alues of these thr ee algor ithm par amet ers ma y dep end on the mesh qualit y.Their default v alues ma y change in futur e releases af ter accumula ting mor e experienc e with the w ave equa tion mo del. The TUI c ommands f or the ac oustics w ave equa tion solution c ontrols ar e found in the menu: /solve/set/acoustics-wave-equation-controls/ The sub-menu /expert allo ws you t o sp ecify under-r elaxa tion fac tors t o enf orce convergenc e on low qualit y meshes . Under nor mal cir cumstanc es, under-r elaxa tion is not r ecommended . 23.3.3. Solution Initializa tion The w ave equa tion mo del is t o be ac tivated af ter the de velopmen t of a time-dep enden t flo w solution. Therefore the ac oustics field r equir es a separ ate initializa tion pr ocess, tha t includes r amping in time the sound sour ce term found in Equa tion 15.11 .With the w ave equa tion mo del enabled , a Sound Potential field and a new butt on Initializ e Acoustics… app ear on the Solution Initializa tion task page .The initial Sound P otential value should alw ays be kept a t zero.The Initializ e Acoustics… butt on op ens the Acoustics Initializa tion dialo g box (Figur e 23.19: The A coustics Initializa tion D ialog Box (p.1907 )), wher e you c an sp ecify the numb er of timest eps f or the r amping pr ocess. Figur e 23.19: The A coustics Initializa tion D ialo g Box You c an r e-initializ e the ac oustics field separ ately a t an y time , sinc e it do es not influenc e the tr ansien t flow solution which is simply c ontinued fur ther . You c an sp ecify the numb er of timest eps f or the r amping pr ocess using the TUI c ommand: /solv e/initializ e/init-ac oustics-options Note If you enable the w ave equa tion mo del in a non-initializ ed setup , then the initializa tion of the en tire simula tion will also initializ e ac oustics . However the r amping dur ation will b e set to zero.You c an r eset the r amping pr ocess b y re-initializing ac oustics separ ately. 1907Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the A coustics Wave Equa tion M odel23.3.4. Post-P rocessing The f ollowing field v ariables ar e available in the Acoustics… group f or p ost-pr ocessing: •Sound P ressur e – main pr actical in terest, connec ted t o the sound p otential b y Equa tion 15.12 .The sound pr essur e field is less smo oth than the sound p otential field b ecause of numer ical diff erentiation. •Sound P otential – pr imar y solution v ariable . •Sound DP/Dt – time der ivative of the sound pr essur e (a sec ond time der ivative of the pr imar y solution v ariable). This field ma y displa y a lot of noise . •Sound WaveEq M odel S our ce – or iginal mo del sour ce term. •Sound WaveEq M odel S our ce Smoothed – sour ce term smo othed b y the time filt er. •Sound WaveEq M odel S our ce M ask – sour ce mask ing mar ker. •Sound S ponge L ayer M arker – sp onge la yer mar ker. Note Both the Sound WaveEq M odel S our ce and Sound WaveEq M odel S our ce Smoothed do not include the eff ects of sour ce mask ing and r amping . In or der t o see the sour ce field af ter the applic ation of mask ing and r amping , you c an use the e xpert output field Sound WaveEq Sour ce in the Acoustics… group , which c an b e enabled b y responding “yes” to the question Keep temporary solver memory from being freed? in the TUI c ommand dialo g of /solve/set/expert . 23.4. Using the Br oadband N oise S our ce M odels In this sec tion, the pr ocedur e for setting up and using the br oadband noise sour ce mo dels is outlined first , followed b y descr iptions of each of the st eps in volved. The gener al pr ocedur e for c arrying out a br oadband noise sour ce calcula tion in ANSY S Fluen t is as f ollows: 1.Calcula te a st eady or unst eady RANS solution. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1908Predic ting A erodynamic ally G ener ated N oise2.Enable the br oadband noise mo del and set the asso ciated mo del par amet ers. Setup → Models → Acoustics Edit... 3.Postpr ocess the noise sour ces. Results → Graphics → Contours Edit... For additional inf ormation, see the f ollowing sec tions: 23.4.1. Enabling the B roadband N oise S ource Models 23.4.2. Postpr ocessing the B roadband N oise S ource Model D ata 23.4.1. Enabling the Br oadband N oise S our ce M odels To enable the br oadband noise sour ces mo dels , selec t Broadband N oise S our ces in the Acoustics Model dialo g box (Figur e 23.20: The A coustics M odel D ialog Box for B roadband N oise (p.1909 )). Setup → Models → Acoustics Edit... Figur e 23.20: The A coustics M odel D ialo g Box for Br oadband N oise 23.4.1.1. Setting Mo del C onstants Under Model C onstan ts in the Acoustics M odel dialo g box, specify the r elevant acoustic par amet ers and c onstan ts used b y the mo del. See Enabling the FW-H A coustics M odel (p.1879 ) for the definitions of Far-F ield D ensit y and Far-F ield S ound S peed . 1909Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the B roadband N oise S ource ModelsReferenc e Acoustic P ower (for e xample , in Equa tion 15.17 in the Theor y Guide ) is used t o comput e the ac oustic p ower outputs in decib els (dB). The default v alue is . Note tha t the units f or the r eference ac oustic p ower will b e different in 2D ( W/m2) and 3D ( W/m3) cases . Numb er of Realiza tions is the numb er of samples used in the SNGR t o comput e the a veraged sour ce terms of LEE and Lille y’s equa tions .The default v alue is 200. Numb er of F our ier M odes ( in Equa tion 15.37 in the Theor y Guide ) is the numb er of the F ourier mo des used t o comput e the turbulen t velocity field and its der ivatives.The turbulen t velocity field is then used t o comput e the LEE and Lille y’s sour ce terms.The default v alue is 50. 23.4.2. Postpr ocessing the Br oadband N oise S our ce M odel D ata The final st ep in the br oadband noise sour ce mo deling pr ocess is the p ostpr ocessing of ac oustic p ower and noise sour ce da ta.The f ollowing v ariables ar e available in the Acoustics ... postpr ocessing c ategor y: •Acoustic P ower L evel (dB) •Acoustic P ower •Jet A coustic P ower L evel (dB) (axisymmetr ic mo dels only) •Jet A coustic P ower (axisymmetr ic mo dels only) •Surface Acoustic P ower L evel (dB) •Surface Acoustic P ower •Lille y’s Self-N oise S our ce •Lille y’s Shear-N oise S our ce •Lille y’s Total N oise S our ce •LEE S elf-N oise X-S our ce •LEE S hear-N oise X-S our ce •LEE Total N oise X-S our ce •LEE S elf-N oise Y-Sour ce •LEE S hear-N oise Y-Sour ce •LEE Total N oise Y-Sour ce •LEE S elf-N oise Z-S our ce (3D mo dels only) •LEE S hear-N oise Z-S our ce (3D mo dels only) •LEE Total N oise Z-S our ce (3D mo dels only) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1910Predic ting A erodynamic ally G ener ated N oiseChapt er 24: Modeling D iscr ete Phase This chapt er descr ibes ho w to use the Lagr angian discr ete phase c apabilities a vailable in ANSY S Fluen t. For inf ormation ab out the theor y behind the discr ete phase mo dels , see Discrete Phase in the Theor y Guide . Information is or ganiz ed in to the f ollowing sec tions: 24.1. Introduction 24.2. Steps f or U sing the D iscrete Phase M odels 24.3. Setting Initial C onditions f or the D iscrete Phase 24.4. Setting B oundar y Conditions f or the D iscrete Phase 24.5. Particle E rosion C oupled with D ynamic M eshes 24.6. Setting M aterial P roperties f or the D iscrete Phase 24.7. Solution S trategies f or the D iscrete Phase 24.8. Postpr ocessing f or the D iscrete Phase 24.9. Parallel P rocessing f or the D iscrete Phase M odel 24.1. Introduc tion In addition t o solving tr ansp ort equa tions f or the c ontinuous phase , ANSY S Fluen t allo ws you t o simula te a discr ete sec ond phase in a Lagr angian fr ame of r eference.This sec ond phase c onsists of spher ical particles (which ma y be tak en t o represen t droplets or bubbles) disp ersed in the c ontinuous phase . ANSY S Fluen t comput es the tr ajec tories of these discr ete phase en tities , as w ell as hea t and mass transf er to/from them. The c oupling b etween the phases and its impac t on b oth the discr ete phase trajec tories and the c ontinuous phase flo w can b e included . ANSY S Fluen t provides the f ollowing discr ete phase mo deling options: •calcula tion of the discr ete phase tr ajec tory using a Lagr angian f ormula tion tha t includes the discr ete phase iner tia, hydrodynamic dr ag, and the f orce of gr avity, for b oth st eady and unst eady flo ws •predic tion of the eff ects of turbulenc e on the disp ersion of par ticles due t o turbulen t eddies pr esen t in the continuous phase •heating/c ooling of the discr ete phase •vaporization and b oiling of liquid dr oplets •combusting par ticles , including v olatile e volution and char c ombustion t o simula te coal c ombustion •optional c oupling of the c ontinuous phase flo w field pr edic tion t o the discr ete phase c alcula tions •droplet br eakup and c oalesc ence •consider ation of par ticle/par ticle c ollisions and v oidage of discr ete phase These mo deling c apabilities allo w ANSY S Fluen t to simula te a wide r ange of discr ete phase pr oblems including par ticle separ ation and classific ation, spr ay dr ying , aer osol disp ersion, bubble stir ring of liquids , liquid fuel c ombustion, and c oal c ombustion. The ph ysical equa tions used f or these discr ete phase 1911Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.calcula tions ar e descr ibed in Discrete Phase in the Fluent Theor y Guide , and instr uctions f or setup , solution, and p ostpr ocessing ar e pr ovided in the r emaining sec tions of this chapt er. Alternative mo dels f or multiphase sy stems use the E uler-E uler appr oach r ather than the E uler-Lagr ange appr oach used in the D iscrete Phase M odel. The E uler-E uler mo dels ar e discussed in Modeling M ultiphase Flows (p.2091 ) along with the D ense D iscrete Phase M odel (DDPM) which is a h ybrid E uler-E uler and Euler-Lagr ange appr oach. The Lagr angian discr ete phase mo del c an b e connec ted t o the E uler ian VOF mo del via VOF-t o-DPM model tr ansf er mechanisms as descr ibed in Using the VOF-t o-DPM M odel Transition f or D ispersion of Liquid in G as (p.2181 ). For e xample , in the simula tion of liquid spr ays, appr oxima tely spher ical liquid structures in the VOF solution c an b e converted aut oma tically in to Lagr angian par ticle par cels.This, in conjunc tion with d ynamic solution-adaptiv e mesh r efinemen t, allo ws for a detailed , yet time-efficien t simula tion of pr imar y atomiza tion, such as , for e xample , in gas turbines and in ternal c ombustion engines . For additional inf ormation, see the f ollowing sec tions: 24.1.1. Concepts 24.1.2. Limita tions 24.1.1. Conc epts This sec tion in troduces se veral concepts in the tr eatmen t of discr ete phase par ticles in F luen t tha t are imp ortant to understand in or der t o get the most out of the r emaining inf ormation in this chapt er. 24.1.1.1. Uncoupled v s. Coupled DPM 24.1.1.2. Steady vs. Unsteady Tracking 24.1.1.3. Parcels 24.1.1.1. Unc oupled v s. Coupled DPM When the fluid changes the par ticles , ther e will b e corresponding eff ects on the fluid . For e xample , when dr ag f orce ac ts on a par ticle , the e xchange of momen tum c an change the fluid flo w.When simula ting par ticles using DPM, you c an cho ose whether or not t o include these eff ects in the flo w solution; these alt ernatives ar e called C oupled and U ncoupled DPM. See Options f or In teraction with the C ontinuous P hase (p.1918 ) for details ab out ho w to sp ecify whether y our simula tion uses C oupled or U ncoupled DPM. In U ncoupled DPM, the only pur pose of the DPM par ticles is f or p ostpr ocessing , and so par ticles ar e not tr acked e xcept when y ou r equest them, for e xample t o calcula te and displa y par ticle tr acks .The particles c an still change b y hea t and mass tr ansf er, but the c orresponding changes (such as v apor from an e vaporating dr oplet) do not aff ect the flo w solution. In a C oupled DPM simula tion, the eff ects of the par ticles ar e used t o influenc e the flo w solution. These effects ar e transmitt ed t o the flo w as DPM S ources.The DPM solution and the flo w solution should reach a c onverged , self-c onsist ent solution. Therefore, ther e ar e se veral options f or running these solutions t ogether—see Solution S trategies f or the D iscrete Phase (p.2022 ). 24.1.1.2. Steady v s. Unst eady Track ing As descr ibed in Steps f or U sing the D iscrete Phase M odels (p.1917 ), to set up a DPM simula tion y ou specify the star ting c onditions of a set of par ticles b y defining an injec tion. By sp ecifying b oundar y conditions and ph ysical sub-mo dels , you also sp ecify ho w these par ticles in teract with other z ones Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1912Modeling D iscrete Phasein the geometr y and ho w the y eventually lea ve the mo del—f or instanc e, the y migh t bounc e off some walls but b e trapp ed b y others . You must also sp ecify ho w Fluen t is t o track the par ticles y ou ha ve defined . If Steady Tracking is en- abled , then, as so on as a par ticle is r eleased , it is tr acked un til it r eaches its final destina tion acc ording to the sp ecified b oundar y behavior (or un til a fix ed numb er of par ticle time st eps ha ve been used). Therefore, each par ticle t ypic ally tr avels thr ough man y cells of the mo del, interacting with the flo w and (in a C oupled DPM simula tion) changing the DPM S ources in each c ell.These sour ces influenc e the flo w solution f or a defined numb er of it erations or time st eps—the flo w solution c an b e steady or unst eady.Then, if requir ed, a new set of par ticle tr ajec tories is tr acked, the DPM S ources ar e up dated, and the sequenc e is r epeated. An example of using S teady DPM with unst eady flo w is when the chosen flo w mo dels r equir e a tr ansien t simula tion, although the final goal is a st eady solution. If Unsteady Tracking is enabled , then each par ticle is ad vanced b y a sp ecified numb er of par ticle time steps, not nec essar ily reaching a final destina tion, before the flo w solution is up dated.When U nsteady DPM is c oupled t o unst eady flo w solution, the par ticles and the flo w de velop in time t ogether c on- currently, although diff erent time st eps c an b e used f or DPM and flo w. Unsteady DPM c an also b e coupled t o steady flo w solution; this mak es sense if ther e is a c ontinuous sour ce of DPM par ticles tha t pass thr ough the sy stem. For st eady or unst eady flo w, ther e ar e se veral DPM mo dels wher e Unsteady Tracking is r equir ed. For e xample , in spr ay coalesc ence and c ollision models , par ticles change with time on the basis of in teractions with other par ticles , so the y must b e tracked simultaneously 24.1.1.3. Parcels Especially when using C oupled DPM, the mass flo w rate of a par ticle injec tion will of ten b e a r equir ed and r elevant input par amet er sinc e it det ermines the absolut e value of the DPM S ources.This mass flow rate could b e converted in to the numb er of par ticles injec ted p er unit time . However, it is of ten prohibitiv e to track tha t numb er of par ticles in a simula tion. Strictly sp eaking, the mo del ther efore tracks a numb er of ‘parcels’, and each par cel is r epresen tative of a fr action of the t otal c ontinuous mass flo w rate (in S teady tracking) or a fr action of the t otal mass flo w released in a time st ep (in U n- steady tracking). It is still sometimes helpful t o refer to each par cel as a r epresen tative par ticle , because it has a sp ecified particle diamet er, and its tr ajec tory in fluid flo w uses the r elaxa tion time appr opriate for a single particle . (The r elaxa tion time is a r atio of par ticle momen tum t o dr ag f orce). However, the par cel’s mass (or mass flo w rate) b ecomes imp ortant when c alcula ting the DPM S ources: for e xample , if a represen tative dr oplet loses a small amoun t of v apor b y evaporation, the o verall eff ect from the whole parcel will t ypic ally b e much lar ger. Other mo dels also use the par cel mass (or mass flo w rate) to calcula te total c oncentrations of DPM ma terial—in par ticular , the D ense D iscrete Phase M odel (DDPM) uses this c oncentration t o feed in to the v olume fr action of the E uler ian phase tha t represen ts the same ma terial. See Dense D iscrete Phase M odel in the Fluent Theor y Guide for details of the D ense Discrete Phase M odel. The c oncept of par cels is par ticular ly imp ortant in the D iscrete Elemen t Metho d (DEM), wher e par cels occup y a finit e volume and obstr uct other DEM par cels.The v olume o ccupied b y a par cel is c alcula ted directly fr om the mass tha t it r epresen ts (so tha t a r ealistic densit y is cr eated when par cels pack t o- gether). The equiv alen t ‘parcel diamet er’ is used f or c alcula ting par cel-par cel contacts and f orces. However, for tr ajec tories thr ough fluid , it is still the ‘particle diamet er’ tha t is used . See Discrete Elemen t Metho d Collision M odel in the Fluent Theor y Guide for details of the D iscrete Elemen t Model. 1913Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.IntroductionThe numb er of par cels in a DPM mo del is chosen in the mo del settings , and not defined b y the tr ue numb er of par ticles .There ar e se veral inputs tha t can b e used t o adjust the numb er of par cels when defining initial c onditions such as the numb er of injec tion lo cations and (f or U nsteady Tracking) the injec tion fr equenc y (Setting Initial C onditions f or the D iscrete Phase (p.1943 )) Other inputs in sub- models include: the numb er of siz es in a siz e distr ibution ( Using the R osin-R ammler D iamet er D istri- bution M etho d (p.1963 )); the numb er of st ochastic tr ies in turbulen t disp ersion ( Specifying Turbulen t Dispersion of P articles (p.1978 )); and the br eakup char acteristics of some spr ays (Breakup (p.1975 )). A high numb er of par cels c an b e computa tionally e xpensiv e, but it is of ten helpful f or c onvergenc e, so that no single par cel has an o verwhelming eff ect on the flo w In gener al you should ar range f or enough parcels t o pr oduce a sta tistic al sample , represen tative of the full r ange of par ticle b ehavior. 24.1.2. Limita tions The discr ete phase mo del limita tions ar e pr ovided in the f ollowing subsec tions . 24.1.2.1. Limita tion on the P article Volume F raction 24.1.2.2. Limita tion on M odeling C ontinuous Susp ensions of P articles 24.1.2.3. Limita tions on M odeling P article R otation 24.1.2.4. Limita tions on U sing the D iscrete Phase M odel with O ther ANSY S Fluen t Models 24.1.2.5. Limita tions on U sing the H ybrid Parallel M etho d 24.1.2.6. Limita tions on U sing the Lagr angian Wall F ilm M odel 24.1.2.1. Limitation on the P article Volume F raction The discr ete phase f ormula tion used b y ANSY S Fluen t contains the assumption tha t the sec ond phase is sufficien tly dilut e tha t par ticle-par ticle in teractions and the eff ects of the par ticle v olume fr action on the gas phase ar e negligible . In pr actice, these issues imply tha t the discr ete phase must b e pr esen t at a fair ly lo w volume fr action, usually less than 10–12%. Note tha t the mass loading of the discr ete phase ma y gr eatly e xceed 10–12%: you ma y solv e pr oblems in which the mass flo w of the discr ete phase equals or e xceeds tha t of the c ontinuous phase . See Modeling M ultiphase F lows (p.2091 ) for information ab out when y ou migh t want to use one of the gener al multiphase mo dels inst ead of the discr ete phase mo del. This limita tion is r elax ed f or some v ariants of DPM. For e xample , the D ense D iscrete Phase M odel (DDPM) adds eff ects due t o friction and v olume fr action, so tha t the c oncentration c an appr oach the pack ing limit. Where high lo cal concentrations of spr ay dr oplets c ause c oalesc ence and c ollision, these phenomena c an b e included in some spr ay mo dels . Parcel-par cel contacts b etween solid par ticles are mo deled in detail in D iscrete Elemen t Models , so tha t par cels c an pack t ogether closely . 24.1.2.2. Limitation on Mo deling C ontinuous S usp ensions of P articles The st eady-par ticle Lagr angian discr ete phase mo del is suit ed f or flo ws in which par ticle str eams ar e injec ted in to a c ontinuous phase flo w with a w ell-defined en trance and e xit c ondition. The Lagr angian model do es not eff ectively mo del flo ws in which par ticles ar e susp ended indefinit ely in the c ontinuum, as o ccurs in solid susp ensions within closed sy stems such as stir red tanks , mixing v essels , or fluidiz ed beds.The unst eady-par ticle discr ete phase mo del, however, is c apable of mo deling c ontinuous sus- pensions of par ticles . See Modeling M ultiphase F lows (p.2091 ) for inf ormation ab out when y ou migh t want to use one of the gener al multiphase mo dels inst ead of the discr ete phase mo dels . 24.1.2.3. Limitations on Mo deling P article R otation When using r otating par ticles , not e the f ollowing limita tions: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1914Modeling D iscrete Phase•In simula tions with enabled st ochastic par ticle c ollision mo dels ( Including C ollision and D roplet C oales- cence (p.1929 )), par ticle r otation is not aff ected b y par ticle/par ticle c ollisions . •Particle r otation is not a vailable f or massless par ticles . •Particle r otation is not c ompa tible with mo ving r eference frame simula tions . •For a tomiz er injec tions , the initial angular v elocity is set t o zero. •The eff ect of the M agnus lif t force on the fluid is not tak en in to acc oun t in DPM c oupled simula tions . 24.1.2.4. Limitations on Using the D iscr ete Phase Mo del with O ther ANSY S Fluent Mo dels The f ollowing r estrictions e xist on the use of other mo dels with the discr ete phase mo del: •When tr acking par ticles with the DPM mo del in c ombina tion with an y of the multiphase flo w models ( VOF, mix ture, or E uler ian—see Modeling M ultiphase F lows (p.2091 )) the Shared M emor y metho d cannot b e selec ted ( Parallel P rocessing f or the D iscrete Phase M odel (p.2066 )). (Note tha t using the Message P assing or Hybr id metho d enables the c ompa tibilit y of all multiphase flo w models with the DPM mo del.) •When using the DPM mo del with the E uler ian multiphase mo del, the tr acked par ticles r ely only on the primar y phase t o comput e dr ag, hea t, and mass tr ansf er. Also, any DPM r elated sour ce terms ar e applied to the pr imar y phase . Particle tr acking r elative to a sec ondar y phase is not pr ovided . •Streamwise p eriodic flo w (either sp ecified mass flo w rate or sp ecified pr essur e dr op) c annot b e mo deled with st eady par ticle tr acks in c oupled simula tion. It is p ossible using tr ansien t par ticle tr acks . •Only non-r eacting par ticles c an b e included when the pr emix ed c ombustion mo del is used . •Surface injec tions will b e mo ved with the mesh when a sliding mesh or a mo ving or def orming mesh is being used , however only those sur faces asso ciated with a b oundar y will b e recalcula ted. Injec tions fr om cut plane sur faces will not b e mo ved with the mesh and will b e delet ed when r emeshing o ccurs . •The cloud mo del is not a vailable f or unst eady par ticle tr acking, and will not allo w you t o use the message passing or h ybrid option f or the par ticles . •The w all film mo del is only v alid f or liquid ma terials. If a nonliquid par ticle in teracts with a w all film boundar y, the b oundar y condition will default t o the r eflec t boundar y condition. •When multiple r eference frames ar e used in c onjunc tion with the discr ete phase mo del, the displa y of particle tr acks will not , by default , be meaning ful. Similar ly, coupled discr ete-phase c alcula tions ar e not meaning ful. An alt ernative appr oach f or par ticle tr acking and c oupled discr ete-phase c alcula tions with multiple reference frames is t o track par ticles based on absolut e velocity inst ead of r elative velocity.To mak e this change , use the define/models/dpm/ options/track-in-absolute-frame text command . Note tha t the r esults ma y str ongly dep end on the lo cation of w alls inside the multiple reference frame . The par ticle injec tion v elocities (sp ecified in the Set Injec tion P roperties dialo g box) ar e defined relative to the fr ame of r eference in which the par ticles ar e tracked. By default , the injec tion v elo- 1915Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Introductioncities ar e sp ecified r elative to the lo cal reference frame . If you enable the track-in-absolute- frame option, the injec tion v elocities ar e sp ecified r elative to the absolut e frame . •Relative par ticle tr acking c annot b e used in c ombina tion with sliding and mo ving def orming meshes . If sliding and/or def orming meshes ar e used with the DPM mo del, the par ticles will alw ays be tracked in the absolut e frame . Switching t o the r elative frame is not p ermitt ed. 24.1.2.5. Limitations on Using the H ybrid P arallel Metho d •The h ybrid par allel DPM tr acking metho d is not a vailable with the f ollowing mo dels and f eatures: –the PDF Transp ort mo del –the DDPM (D ense DPM) mo del with the Volume F raction A ppr oaching P ack ing Limit option selec ted in the Discr ete Phase dialo g box –the Stochastic C ollision mo del (with or without the dr oplet c oalesc ence) –Graphic al displa y of par ticle tr acks –Sampling of par ticle tr acks in sample files –Export of par ticle tr acks in to par ticle hist ory files If an y of these mo dels or f eatures ar e used , Fluen t will silen tly fall back t o the Message P assing parallel DPM tr acking option. •The Use DPM D omain option of the Hybr id par allel DPM tr acking metho d will not b e used in an y of the f ollowing situa tions: –if the E uler ian Wall F ilm mo del is enabled –if the PDF Transp ort mo del is enabled –if the c ase has a d ynamic z one –if the c ase has a sliding in terface –if the c ase includes non-z onal sur face injec tions (tha t is, injec tions tha t ha ve positions defined thr ough surfaces tha t are not z one sur faces) If the Use DPM D omain option is enabled in such c ases , ANSY S Fluen t will issue a message w arning that the DPM D omain is suppr essed .You c an a void this message b y disabling the Use DPM D omain option in the Parallel tab of the Discr ete Phase M odel dialo g box. For additional limita tions asso ciated with the h ybrid par allel metho d, see Limita tions on U sing the Discrete Phase M odel with O ther ANSY S Fluen t Models (p.1915 ). 24.1.2.6. Limitations on Using the L agr angian Wall F ilm Mo del •The Lagr angian w all film mo del is only a vailable with Unstead y Particle Track ing. •The Lagr angian w all film mo del is not c ompa tible with hanging no de mesh r efinemen t on w alls.Though the fluid meshes c an b e adapt ed, the r efined meshes must not t ouch w alls wher e the w all film mo del is enabled . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1916Modeling D iscrete Phase•The w all film mo del assumes liquid par ticle ma terials. If an iner t par ticle in teracts with a w all film b oundar y, it is assumed t o be liquid f or the w all film mo del c alcula tions . For combusting par ticles , the w all film is applied if Wet C ombustion M odel is enabled and as long as the liquid fr action in the par ticle is nonz ero. If a dr y combusting par ticle in teracts with a w all film b oundar y it will stick t o the w all and f ollow the combusting par ticle la ws. •The w all film mo del is not c ompa tible with the R osseland R adia tion mo del. •The Workpile A lgor ithm option is not a vailable with the w all film b oundar y condition. It will b e disabled automa tically when cho osing t o simula te a w all film on a w all. For additional assumptions used b y the Lagr angian w all film mo del, refer to Introduc tion and Interaction During Impac t with a B oundar y in the Fluent Theor y Guide . 24.2. Steps f or U sing the D iscr ete Phase M odels You c an include a discr ete phase in y our ANSY S Fluen t mo del b y defining the initial p osition, velocity, size, and t emp erature of individual par ticles .These initial c onditions , along with y our inputs defining the ph ysical pr operties of the discr ete phase , are used t o initia te trajec tory and hea t/mass tr ansf er cal- cula tions .The tr ajec tory and hea t/mass tr ansf er calcula tions ar e based on the f orce balanc e on the particle and on the c onvective/radia tive hea t and mass tr ansf er fr om the par ticle , using the lo cal con- tinuous phase c onditions as the par ticle mo ves thr ough the flo w.The pr edic ted tr ajec tories and the asso ciated hea t and mass tr ansf er can b e view ed gr aphic ally and/or alphanumer ically. The pr ocedur e for setting up and solving a pr oblem in volving a discr ete phase is outlined b elow, and descr ibed in detail in Options f or In teraction with the C ontinuous P hase (p.1918 ) – Postpr ocessing f or the D iscrete Phase (p.2027 ). Only the st eps r elated sp ecific ally t o discr ete phase mo deling ar e sho wn here. For inf ormation ab out inputs r elated t o other mo dels tha t you ar e using in c onjunc tion with the discr ete phase mo dels , see the appr opriate sec tions f or those mo dels . 1.Enable an y of the discr ete phase mo deling options , if relevant, as descr ibed in Options f or In teraction with the C ontinuous P hase (p.1918 ). 2.Choose a tr ansien t or st eady treatmen t of par ticles as descr ibed in Steady/Transien t Treatmen t of Particles (p.1918 ). 3.Specify tr acking par amet ers as descr ibed in Tracking P aramet ers f or the D iscrete Phase M odel (p.1923 ). 4.Enable the r equir ed ph ysical submo dels f or the discr ete phase mo del, as descr ibed in Physical M odels f or the D iscrete Phase M odel (p.1925 ). 5.Set the numer ics par amet ers and solv e the pr oblem, as descr ibed in Numer ics of the D iscrete Phase M od- el (p.1937 ) and Solution S trategies f or the D iscrete Phase (p.2022 ). 6.Specify the injec tion-sp ecific mo dels , initial c onditions , and par ticle siz e distr ibutions as descr ibed in Setting Initial C onditions f or the D iscrete Phase (p.1943 ). 7.Define the b oundar y conditions , as descr ibed in Setting B oundar y Conditions f or the D iscrete Phase (p.1985 ). 8.Define the ma terial pr operties, as descr ibed in Setting M aterial P roperties f or the D iscrete Phase (p.2008 ). 9.Initializ e the flo w field . 10.Solve the c oupled or unc oupled flo w (Solution S trategies f or the D iscrete Phase (p.2022 )). 1917Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Steps f or U sing the D iscrete Phase M odels11.For tr ansien t cases , advance the solution in time b y tak ing the desir ed numb er of time st eps. Particle p os- itions will b e up dated as the solution ad vances in time . If you ar e solving an unc oupled flo w, the par ticle position will b e up dated a t the end of each time st ep. For a c oupled c alcula tion, the p ositions ar e iterated on or within each time st ep. 12.Examine the r esults , as descr ibed in Postpr ocessing f or the D iscrete Phase (p.2027 ). 24.2.1. Options f or In teraction with the C ontinuous P hase If the discr ete phase in teracts (tha t is, exchanges mass , momen tum, and/or ener gy) with the c ontinuous phase , you should enable Interaction with C ontinuous P hase . Setup → Models → Discr ete Phase Continuous P hase In teraction → On An input f or the DPM I teration In terval will app ear, which allo ws you t o control the fr equenc y at which the par ticles ar e tracked and the DPM sour ces ar e up dated. For st eady-sta te simula tions , incr easing the DPM I teration In terval will incr ease stabilit y but r equir e mor e iterations t o converge. In addition, another option e xists tha t allo ws you t o control the numer ical tr eatmen t of the sour ce terms and ho w the y are applied t o the c ontinuous phase equa tions . For unst eady simula tions ,Update DPM S our ces E very Flow Iteration is the default (and r ecommended) option; at every DPM I teration, the par ticle sour ce terms ar e recalcula ted.The sour ce terms applied t o the c ontinuous phase equa tions transition t o the new v alues e very flo w it eration based on Equa tion 16.473 to Equa tion 16.475 in the Theor y Guide .This pr ocess is c ontrolled b y the under-r elaxa tion fac tor, specified in the Solution Controls task page , see Under-R elaxa tion of the In terphase Ex change Terms (p.2025 ). 24.2.2. Stead y/Transien t Treatmen t of P articles The D iscrete Phase M odel uses a Lagr angian appr oach t o der ive the equa tions f or the under lying physics, which ar e solv ed tr ansien tly.Transien t numer ical pr ocedur es in the D iscrete Phase M odel c an be applied t o resolv e steady flo w simula tions as w ell as tr ansien t flo ws. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1918Modeling D iscrete PhaseIn the Discrete Phase M odel D ialog Box (p.3360 ) you ha ve the option of cho osing whether y ou w ant to treat the par ticles in an unst eady or a st eady fashion. This option c an b e chosen indep enden t of the settings f or the solv er.Thus, you c an p erform st eady-sta te trajec tory simula tions e ven when selec ting a transien t solv er for numer ical reasons .You c an also sp ecify unst eady par ticle tr acking when solving the st eady continuous phase equa tions .This c an b e used t o impr ove numer ical stabilit y for v ery lar ge particle sour ce terms or simply f or p ostpr ocessing pur poses .Whene ver y ou enable a br eakup or c ollision model t o simula te spr ays, the Unstead y Particle Track ing will b e swit ched on aut oma tically. When Unstead y Particle Track ing is enabled , several new options app ear. If steady-sta te equa tions are solv ed f or the c ontinuous phase , you simply en ter the Particle Time S tep S ize and the Numb er of Time S teps, thus tr acking par ticles e very time a DPM it eration is c onduc ted.When y ou incr ease the Numb er of Time S teps, the dr oplets p enetr ate the domain fast er. When solving unst eady equa tions f or the c ontinuous phase , you must decide whether y ou w ant to use Fluid F low Time S tep to injec t the par ticles , or y ou pr efer a Particle Time S tep S ize indep enden t of the Fluid F low Time S tep.With the la tter option, you c an use the D iscrete Phase M odel in c ombin- ation with changes in the time st ep f or the c ontinuous equa tions , as it is done when using adaptiv e flow time st epping . If you do not use Fluid F low Time S tep, you must decide when t o injec t the par ticles f or a new time step.You c an either Injec t Particles a t Particle Time S tep or a t the Fluid F low Time S tep. In an y case, the par ticles will alw ays be tracked in such a w ay tha t the y coincide with the flo w time of the continuous flo w solv er, as long as the maximum numb er of time st eps used t o comput e a single tr a- jectory is sufficien t (see Tracking P aramet ers f or the D iscrete Phase M odel (p.1923 ) for details). You c an use a user-defined func tion (DEFINE_DPM_TIMESTEP ) to change the time st ep f or DPM particle tr acking.The time st ep c an b e pr escr ibed f or sp ecial applic ations wher e a c ertain time st ep is needed . For mor e inf ormation ab out changing the time st ep siz e for DPM par ticle tr acking, see DEFINE_DPM_TIMESTEP in the Fluen t Customiza tion M anual . Imp ortant When the densit y-based solv er is used with the e xplicit unst eady formula tion, the par ticles are ad vanced onc e per time st ep and ar e calcula ted a t the star t of the time st ep (b efore the flo w is up dated). Additional inputs ar e requir ed f or each injec tion in the Set Injec tion P roperties D ialog Box (p.3917 ), as detailed in Defining Injec tion P roperties (p.1969 ). For Unstead y Particle Track ing, the injec tion Start Time and Stop Time must b e sp ecified under Point Properties . Injec tions with star t and st op times set t o zero will b e injec ted only a t the star t of the c alcula tion ( ). If the In-C ylinder mesh motion is enabled , the star t and st op times ar e replac ed b y Start Crank A ngle and Stop C rank A ngle , respectively. The injec tion sp ecified in this w ay will b e repeated a t the star ting and st opping cr ank angle if the simula tion is r un thr ough mor e than one c ycle. Changing injec tion settings dur ing a tr ansien t simula tion will not aff ect par ticles cur rently r eleased in the domain. At an y point dur ing a simula tion, you c an clear par ticles tha t are cur rently in the domain b y click ing the Clear P articles butt on in the Discrete Phase M odel D ialog Box (p.3360 ). You c an cho ose the Parcel Release M etho d to det ermine ho w ANSY S Fluen t creates par cels. For an overview of the c oncept of par cels, see Parcels (p.1913 ).The metho ds a vailable ar e: standar d injec ts a single par cel per injec tion str eam p er time st ep.The numb er of par ticles in the par cel, , is determined as f ollows: 1919Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Steps f or U sing the D iscrete Phase M odels(24.1) wher e, is the numb er of par ticles in a par cel is the mass flo w rate of the par ticle str eam is the time st ep is the par ticle mass This is the default metho d. constan t-numb er injec ts par cels with a user-sp ecified numb er of par ticles p er par cel.The numb er of par cels is det ermined to sa tisfy the sp ecified mass-flo w rate and par ticle siz e distr ibution f or the injec tion. constan t-mass injec ts par cels with a user-sp ecified par cel mass .The numb er of par cels is det ermined t o sa tisfy the sp ecified mass-flo w rate and par ticle siz e distr ibution f or the injec tion. constan t-diamet er injec ts par cels with a user-sp ecified par cel diamet er.The numb er of par cels is det ermined t o sa tisfy the specified mass-flo w rate and par ticle siz e distr ibution f or the injec tion. Note tha t for a tomiz er injec tions ,file injec tions , or injec tions tha t use the DEFINE_DPM_INJEC- TION_INIT user defined func tion, the F luen t solv er aut oma tically uses the default standar d par cel release metho d. Other par cel release metho ds ar e not a vailable . For c ases in volving spr ays and par ticle siz e distr ibutions in gener al, the r ecommended setting f or Parcel Release M etho d is constan t-numb er. For DEM simula tions , you c an use constan t-diamet er or constan t-mass to ensur e tha t the par cel diamet er do es not e xceed the siz e of the smallest c ells in the c omputa tional mesh. Note tha t a lo wer v alue sp ecified f or constan t-numb er,constan t-mass , or constan t-diamet er will result in a lar ger numb er of par cels injec ted and a finer discr etiza tion of the DPM phase .This ma y be beneficial f or accur acy and stabilit y of the c alcula tion, at the e xpense of additional c omputa tional c ost. The Parcel Release M etho d is sp ecified in the Parcel tab of the Set Injec tion P roperties dialo g box. You c an also cho ose one of se veral metho ds t o control when the par ticles ar e tracked. •In st eady-sta te simula tions , par ticles ar e tracked a t the user-sp ecified in tervals ( DPM I teration In terval). Individual par ticles ar e tracked fr om their injec tion p osition un til either the y esc ape the domain or c ertain termina tion cr iteria ar e met. Particle tr acking is p erformed only if the global Numb er of I terations is equal to or e xceeds DPM I teration In terval.The par ticle sour ces ar e up dated dur ing tr acking, and then applied to the gas phase in subsequen t flo w iterations . •In tr ansien t flo w simula tions , par ticle tr acking alw ays occurs a t the b eginning of each flo w time st ep, irre- spective of DPM I teration In terval.The par ticles ar e ad vanced in time based on the cur rent continuous- phase solution, and DPM sour ces ar e up dated.The DPM sour ces pr evail up t o the ne xt time the par ticle tracker is r un. •(transien t flo w) If the DPM I teration In terval is lar ger than or equal t o Max I terations/T ime S tep, then particles ar e tracked only onc e per time st ep. If the DPM I teration In terval is less than Max I terations/T ime Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1920Modeling D iscrete PhaseStep, then the par ticle tr acker is r un multiple times dur ing the time st ep. Each time the par ticle tr acker is used , par ticles ar e retur ned t o their or iginal sta te at the b eginning of the time st ep.Then par ticles ar e ad- vanced in time based on the cur rent continuous-phase solution, and DPM sour ces ar e up dated. If Particle Time S tep is lar ger than Fluid F low Time S tep (to allo w injec tion of par ticles a t a diff erent time sc ale than the fluid), then par ticles ar e ad vanced only f or the fluid flo w time st ep. •(transien t flo w) If you sp ecify a v alue of z ero as the DPM I teration In terval, the par ticles ar e ad vanced a t the end of the time st ep. Note tha t if y ou ha ve pr eviously enabled the r esetting of DPM sour ce terms a t the b eginning of e very time st ep using the TUI c ommand define/models/dpm/interaction/reset- sources-at-timestep? , ANSY S Fluen t will disable this option onc e you set the DPM I teration In terval to zero, because this f eature combina tion is not ad visable . In cases wher e Interaction with C ontinuous P hase is enabled , you must pr ovide a sufficien t numb er of par ticle sour ce term up dates to ensur e tha t par ticle sour ce terms r each their final v alues (see Fig- ure 24.40: Effect of N umb er of S ource Term U pdates on S ource Term A pplied t o Flow Equa tions (p.2026 )). This c an b e achie ved either b y setting the DPM under-r elaxa tion fac tor to 1 or in other c ases b y enabling Update DPM S our ces E very Flow Iteration . If the la tter is disabled and the DPM under-r elaxa tion factor is less than 1, then the v alue y ou sp ecify f or DPM I teration In terval must b e small c ompar ed to Max I terations/T ime S tep. Imp ortant •In st eady-sta te discr ete phase mo deling , par ticles do not in teract with each other and ar e tracked one a t a time in the domain. •If the c ollision mo del is used , you will not b e able t o set the DPM I teration In terval. Refer to Collision and D roplet C oalesc ence Model Theor y in the Fluent Theor y Guide for details ab out this limita tion. Note As explained in Setting Initial C onditions f or the D iscrete Phase (p.1943 ), the injec tion flo w rate is defined p er unit met er of depth in 2D pr oblems . In such c ases , each injec ted par cel is consider ed t o be a solid c ylinder of diamet er and depth 1 met er.The par cel volume is then e xpressed as: However, the par ticles tha t are dense-pack ed in the par cel ar e assumed t o be spher es rather than pucks (ic e-ho ckey).The v olume of each par ticle is the same as in 3D c ases: Consider ne xt the theor etical atomic pack ing fac tor of spher ical par ticles in a c ylinder of one met er depth, also e xpressed as the v olume r atio of all par ticles t o all injec ted par cels. In 2D , the par ticles of diamet er are stack ed on t op of one another in a c ylinder of dia- met er and depth 1 met er.The t otal numb er of par ticles tha t can b e stack ed in the c ylinder in such a w ay is .The t otal v olume o ccupied b y these par ticles is 1921Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Steps f or U sing the D iscrete Phase M odelsThe v olume of the sur rounding par cel cylinder of depth 1 m is The a tomic pack ing fac tor will ha ve a c onstan t value of 2/3 when e xpressed as: In or der t o use the same par amet ers (spr ing c onstan t and c oefficien t of r estitution ) for the DEM spr ing dashp ot mo dels in b oth 3D and 2D simula tions , par cels of the same mass must b e injec ted in 3D and 2D . In 3D , the injec ted par cel is a spher e with diamet er and mass .The numb er of spher ical par ticles in a spher ical par cel is c alcula ted b y In 2D , the par cel is a c ylinder of 1 m depth. This c ylinder has the same mass as the spher ical parcel in 3D ( ), but its v olume diff ers and is c alcula ted as: The numb er of par ticles p er c ylindr ical par cel NP and the v olume the y occup y is the same as in 3D , tha t is Since the r atio of these t wo volumes must b e equal t o the theor etical atomic pack ing fac tor , we obtain The par cel diamet er in 2D c an then b e calcula ted as: Note tha t in 2D , the par cel diamet er is used as a c ollision r ange and it is diff erent than the par cel diamet er in 3D . For each par cel release metho d, the input v alues f or the par cel mass and par cel diamet er ( and , respectively) ar e the same in b oth 3D and 2D , while the output v alues f or parcel diamet ers ar e diff erent: in 2D simula tions and in 3D simula tions . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1922Modeling D iscrete Phase24.2.3. Track ing P aramet ers f or the D iscr ete Phase M odel You will use t wo par amet ers t o control the time in tegration of the par ticle tr ajec tory equa tions: •the maximum numb er of time st eps This fac tor is used t o ab ort trajec tory calcula tions when the par ticle ne ver e xits the flo w domain. •the length sc ale/st ep length fac tor This fac tor is used t o set the time st ep f or in tegration within each c ontrol volume . Each of these par amet ers is set in the Discrete Phase M odel D ialog Box (p.3360 ) (Figur e 24.1: The D iscrete Phase M odel D ialog Box and the Tracking P aramet ers (p.1923 )) under Track ing P aramet ers in the Track ing tab . Setup → Models → Discr ete Phase Edit... Figur e 24.1: The D iscr ete Phase M odel D ialo g Box and the Track ing P aramet ers 1923Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Steps f or U sing the D iscrete Phase M odelsMax. Numb er of S teps is the maximum numb er of time st eps used t o comput e a single par ticle tr ajec tory via in tegration of Equa tion 16.1 in the Theor y Guide .When the maximum numb er of st eps is e xceeded , ANSY S Fluen t abandons the tr ajec tory calcula tion f or the cur rent par ticle injec tion and r eports the tr ajec tory fate as “incomplet e”.The limit on the numb er of in tegration time st eps elimina tes the p ossibilit y of a par ticle being c augh t in a r ecircula ting r egion of the c ontinuous phase flo w field and b eing tr acked infinit ely.The default v alue f or this par amet er is 50,000 f or st eady-sta te par ticle tr acking and 500 f or unst eady par ticle tracking. Note tha t you ma y easily cr eate pr oblems in which the default v alue is insufficien t for completion of the tr ajec tory calcula tion. In this c ase, when tr ajec tories ar e reported as inc omplet e within the domain and the par ticles ar e not r ecircula ting indefinit ely, you c an incr ease the maximum numb er of st eps (up to a limit of ). Note If, when op ening a pr evious simula tion with unst eady DPM par ticle tr acking, you r eceive a warning r eporting tha t a fr action of the discr ete phase mass is "b ehind in time", you can use the r eported p ercentage v alues t o det ermine if it is a signific ant enough discr ep- ancy to warrant revising the simula tion t o ha ve a higher v alue f or Max. Numb er of Steps. Length Sc ale controls the in tegration time st ep siz e used t o integrate the equa tions of motion f or the par ticle .The in- tegration time st ep is c omput ed b y ANSY S Fluen t based on a sp ecified length sc ale , and the v elocity of the par ticle ( ) and of the c ontinuous phase ( ): (24.2) wher e is the Length Sc ale tha t you define . As defined b y Equa tion 24.2 (p.1924 ), is pr oportional to the in tegration time st ep and is equiv alen t to the distanc e tha t the par ticle will tr avel b efore its motion equa tions ar e solv ed again and its tr ajec tory is up dated. A smaller v alue f or the Length Scale incr eases the accur acy of the tr ajec tory and hea t/mass tr ansf er calcula tions f or the discr ete phase . (Note tha t par ticle p ositions ar e alw ays comput ed when par ticles en ter/lea ve a c ell; even if y ou specify a v ery lar ge length sc ale, the time st ep used f or in tegration will b e such tha t the c ell is traversed in one st ep.) Length Sc ale will app ear in the Discr ete Phase M odel dialo g box when the Specify L ength Sc ale option is enabled . Step L ength F actor also c ontrols the time st ep siz e used t o integrate the equa tions of motion f or the par ticle . It diff ers fr om the Length Sc ale in tha t it allo ws ANSY S Fluen t to comput e the time st ep in t erms of the numb er of time steps r equir ed f or a par ticle t o traverse a c omputa tional c ell.To set this par amet er inst ead of the Length Scale, turn off the Specify L ength Sc ale option. The in tegration time st ep is c omput ed b y ANSY S Fluen t based on a char acteristic time tha t is r elated to an estima te of the time r equir ed f or the par ticle t o traverse the cur rent continuous phase c ontrol volume . If this estima ted tr ansit time is defined as , ANSY S Fluen t cho oses a time st ep as (24.3) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1924Modeling D iscrete Phasewher e is the Step L ength F actor. As defined b y Equa tion 24.3 (p.1924 ), is in versely pr oportional to the in tegration time st ep and is r oughly equiv alen t to the numb er of time st eps r equir ed t o traverse the cur rent continuous phase c ontrol volume . A lar ger v alue f or the Step L ength F actor decr eases the discr ete phase in tegration time st ep.The default v alue f or the Step L ength F actor is 5. Step L ength F actor will app ear in the Discr ete Phase M odel dialo g box when the Specify Length Sc ale option is off (the default setting). For st eady-sta te par ticle tr acking, one simple gener al rule t o follow when setting the par amet ers ab ove is tha t if y ou w ant the par ticles t o ad vance thr ough a domain c onsisting of mesh c ells in to the main flow dir ection, the Step L ength F actor times should b e appr oxima tely equal t o the Max. Numb er of S teps. When Accur acy Control is enabled in the Numer ics tab , the settings f or Step L ength F actor and Length Sc ale will b e used only t o estima te the time st ep of the first in tegration st ep. In all subsequen t integration st eps, the par ticle in tegration time st ep is adapt ed t o achie ve the t oler ance sp ecified in Numer ics of the D iscrete Phase M odel (p.1937 ). 24.2.4. Drag L aws There ar e eigh t drag la ws for the par ticles tha t can b e selec ted f or each injec tion. These ar e sp ecified on the Physical M odels tab of the Set Injec tion P roperties dialo g box. See Specifying Injec tion- Specific P hysical M odels (p.1973 ) for details . 24.2.5. Physical M odels f or the D iscr ete Phase M odel This sec tion pr ovides instr uctions f or using the optional discr ete phase mo dels a vailable in ANSY S Fluen t. All of them c an b e enabled in the Physical M odels tab of the Discr ete Phase M odel dialo g box (Figur e 24.2: The D iscrete Phase M odel D ialog Box and the P hysical M odels (p.1926 )). Setup → Models → Discr ete Phase Edit... 1925Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Steps f or U sing the D iscrete Phase M odelsFigur e 24.2: The D iscr ete Phase M odel D ialo g Box and the P hysical M odels 24.2.5.1. Including R adiation H eat Transfer E ffec ts on the P articles If you w ant to include the eff ect of r adia tion hea t transf er to the par ticles ( Equa tion 5.34 in the Theor y Guide ), you must enable the Particle R adia tion In teraction option under the Physical M odels tab , in the Discrete Phase M odel D ialog Box (p.3360 ) (Figur e 24.2: The D iscrete Phase M odel D ialog Box and the P hysical M odels (p.1926 )).You also must define additional pr operties f or the par ticle ma terials (emissivit y and sc attering fac tor), as descr ibed in Descr iption of the P roperties (p.2013 ).This option is available only when the P-1 or discr ete or dina tes radia tion mo del is used . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1926Modeling D iscrete Phase24.2.5.2. Including Thermophor etic F orce Effec ts on the P articles If you w ant to include the eff ect of the ther mophor etic f orce on the par ticle tr ajec tories ( Equa tion 16.11 in the Theor y Guide ), enable the Thermophor etic F orce option under the Physical M odels tab , in the Discrete Phase M odel D ialog Box (p.3360 ).You also must define the ther mophor etic c oefficien t for the par ticle ma terial, as descr ibed in Descr iption of the P roperties (p.2013 ). 24.2.5.3. Including S affman Lif t Force Effec ts on the P articles For sub-micr on par ticles , you c an also mo del the lif t due t o shear (the S affman lif t force, descr ibed in Saffman ’s Lif t Force in the Theor y Guide ) in the par ticle tr ajec tory.To do this , enable the Saffman Lift Force option under the Physical M odels tab , in the Discrete Phase M odel D ialog Box (p.3360 ). 24.2.5.4. Including the Virtual M ass F orce and P ressur e Gr adient E ffec ts on P articles In cases wher e the densit y of the fluid appr oaches or e xceeds the densit y of the par ticles (f or e xample liquid flo w with gaseous bubbles), it is r ecommended tha t you include the Virtual M ass and P ressur e Gradien t forces in the par ticle f orce balanc e.To do this , enable Virtual M ass F orce and Pressur e Gradien t Force under the Physical M odels tab in the Discrete Phase M odel D ialog Box (p.3360 ). See Other F orces in Fluen t Theor y Guide for inf ormation on the Virtual M ass and P ressur e Gradien t forces. 24.2.5.5. Monit oring E rosion/A ccretion of P articles at Walls To monit or par ticle er osion and accr etion r ates a t wall b oundar ies: 1.Enable Erosion/A ccretion in the Physical M odels tab of the Discrete Phase M odel D ialog Box (p.3360 ). Enabling the Erosion/A ccretion option will c ause the er osion and accr etion r ates to be calcula ted at wall b oundar y fac es when par ticle tr acks ar e up dated. 2.For each w all z one , selec t erosion mo dels and sp ecify er osion mo del par amet ers as descr ibed in Setting Particle E rosion and A ccretion P aramet ers (p.1996 ). 3.If you w ant to couple par ticle er osion with d ynamic meshes t o acc oun t for changes in the shap e and position of er oded w alls, follow the pr ocedur e descr ibed in Particle E rosion C oupled with D ynamic Meshes (p.2001 ). 24.2.5.6. Pressur e O ptions for Vaporization Mo dels You c an use the t ext interface command define/models/dpm/options/use-absolute-pressure-for-vaporization? to selec t whether the absolut e pr essur e or a c onstan t Operating P ressur e (set in the Operating Conditions dialo g box) is used in the v aporization r ate calcula tions . The default and r ecommended setting is t o use the absolut e pr essur e. However, in some inc ompr essible flow cases , when ther e ar e lar ge pr essur e variations in the dr oplet injec tion r egion, selec ting the constan t op erating pr essur e ma y stabiliz e the solution. See Operating P ressur e, Gauge P ressur e, and A bsolut e Pressur e (p.1153 ) and Equa tion 8.87 (p.1153 ) for definitions of the op erating pr essur e and absolut e pr essur e. 1927Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Steps f or U sing the D iscrete Phase M odels24.2.5.7. Enabling P ressur e Dependent B oiling With this option y ou c an mo dify the c ondition f or swit ching fr om dr oplet v aporization (La w 2) t o boiling (La w 3). By default ANSY S Fluen t will swit ch fr om the v aporization t o the b oiling la w when the par ticle t emp erature has r eached the b oiling p oint defined f or the dr oplet ma terial (Equa tion 16.121 in the Theor y Guide ).When the Pressur e D ependen t Boiling option is enabled , the swit ching c ondition will change t o , wher e is the sa turation v apor pr essur e at the dr oplet t emp erature and is the domain pr essur e. If while in the b oiling la w, the mo del will swit ch back t o the v aporiz- ation la w. If this option is enabled it is essen tial t o en ter the appr opriate dr oplet sa turation v apor pressur e da ta to cover the c omplet e pr essur e/temp erature range in y our mo del. When Pressur e D ependen t Boiling is enabled , then the Temp erature D ependen t Latent Heat model aut oma tically applies (see Including the E ffect of D roplet Temp erature on La tent Heat (p.1929 )). Setting the Pressur e D ependen t Boiling option has no eff ect on the multic omp onen t par ticles , wher e swit ching fr om the v aporization t o the b oiling r egime is alw ays based on the c omp onen t sat- uration v apor pr essur es (see Multic omp onen t Particle D efinition (La w 7) in the Theor y Guide ). In the sup ercritical pr essur e regime , failur e of the sa turation t emp erature calcula tion algor ithm ma y indic ate tha t the multic omp onen t droplet has appr oached the cr itical temp erature, provided tha t you ha ve en tered accur ate vapor pr essur e da ta for all c omp onen ts. In such a c ase, you c an use the following t ext command: define/models/dpm/options/treat-multicomponent-saturation-temperature- failure? Dump multicomponent particle mass if the saturation temperature calcu- lation fails? [no] y When this option is enabled , ANSY S Fluen t dumps the par ticle mass in to the c ontinuous phase if the saturation t emp erature calcula tion fails . Finally , selec tion of the Pressur e D ependen t Boiling option is not a vailable with the r eal-gas mo dels , as the pr essur e dep endenc e alw ays applies . See Using the C ubic E qua tion of S tate M odels with the Lagr angian D ispersed P hase M odels (p.1171 ) for mor e inf ormation. For pr essur es higher than the cr itical pr essur e of the dr oplet ma terial ( ), a b oiling p oint , defined as the t emp erature at the sa turation v apor pr essur e ( ), cannot b e det ermined as the vapor pr essur e cur ve is defined only up t o the cr itical p oint. Under sup ercritical pr essur e conditions ( ), the v aporization mo dels ar e applic able a t droplet t emp eratures b elow the cr itical p oint ( ), and the swit ching c ondition fr om v aporization t o boiling is ne ver met. For sup ercritical pr essur e conditions , you must en ter the dr oplet sa turation v apor pr essur e da ta for the c omplet e pr essur e/tem- perature range up t o the cr itical p oint . When Pressur e D ependen t Boiling is enabled , you c an use the t ext user in terface command /define/models/dpm/options/allow-supercritical-pressure-vaporization? to enf orce the swit ching fr om v aporization t o boiling e ven if the b oiling p oint is not c alcula ted from the v apor pr essur e da ta. If the pr essur e in y our mo del is ab ove cr itical ( ), you must r etain the default setting ( yes ) for allow-supercritical-pressure-vaporization? . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1928Modeling D iscrete PhaseFor sub critical pr essur e conditions ( ), the setting f or allow-supercritical-pressure- vaporization? will ha ve no eff ect unless the b oiling p oint calcula tion fails , which usually indic ates that either the v apor pr essur e da ta do not c over the c omplet e temp erature/pr essur e range f or y our model, or inaccur ate da ta ha ve been en tered. In tha t case, if allow-supercritical-pressure- vaporization? is set t o no, the nor mal b oiling p oint defined f or the dr oplet ma terial will b e imp osed as a swit ching c ondition fr om v aporization t o boiling . 24.2.5.8. Including the E ffec t of D roplet Temp eratur e on L atent H eat To include the dr oplet t emp erature eff ects on the la tent hea t as descr ibed in Equa tion 16.114 in the Theor y Guide , enable Temp erature D ependen t Latent Heat under the Physical M odels tab . If you enable this option y ou must pr ovide accur ate temp erature-dep enden t sp ecific hea t da ta for b oth the droplet and the e vaporating sp ecies ma terials. 24.2.5.9. Including the E ffec t of P articles on Turbulent Q uantities Particles c an damp or pr oduce turbulen t eddies [84] (p.4009 ). In ANSY S Fluen t, the f ormula tion descr ibed in [32] (p.4006 ) and [6] (p.4005 ) is used t o comput e turbulenc e mo dula tion. Damping o ccurs when the particle diamet er is less than one t enth of the turbulen t length sc ale. For lar ger par ticle diamet ers turbulenc e kinetic ener gy is pr oduced [42] (p.4007 ). If you w ant to consider these eff ects in the chosen turbulenc e mo del, you c an enable this using Two- Way Turbulenc e Coupling , under the Physical M odels tab . 24.2.5.10. Including C ollision and D roplet C oalesc enc e To include the eff ect of c ollisions , as descr ibed in Collision and D roplet C oalesc ence M odel Theor y in the Theor y Guide , selec t Stochastic C ollision and Coalesc enc e under Options . Note Coalesc enc e will app ear under Options after Stochastic C ollision has b een enabled . 24.2.5.11. Including the DEM C ollision Mo del The DEM c ollision mo del is suitable f or simula ting gr anular ma tter, wher e such simula tions ar e char- acterized b y a high v olume fr action of par ticles , and the par ticle-par ticle in teraction is imp ortant. See Modeling C ollision U sing the DEM M odel (p.1930 ) for details ab out using this mo del. 24.2.5.12. Including D roplet Br eak up To mo del dr oplet br eakup in ANSY S Fluen t, enable Break up under Options . By default , this will enable Consider C hildr en in the S ame Track ing S tep and br eakup f or all suitable injec tions .You c an then specify the br eakup mo dels and par amet ers (or disable br eakup) f or each individual injec tion on the Physical M odels tab in the Set Injec tion P roperties dialo g box as descr ibed in Breakup (p.1975 ). The Consider C hildr en in the S ame Track ing S tep option c ollec ts newly gener ated child dr oplets and tr ack them within the same time st ep. It provides higher accur acy and c an lead t o fast er conver- genc e within a tr ansien t flo w time st ep.This option is also aut oma tically enabled if y ou selec t wall- film as Boundar y Cond .Type in the Wall dialo g box (DPM tab). 1929Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Steps f or U sing the D iscrete Phase M odels24.2.5.13. Mo deling C ollision Using the DEM Mo del To enable the DEM c ollision mo del, selec t DEM C ollision under Options . A detailed descr iption of this mo del c an b e found in Discrete Elemen t Metho d Collision M odel in the Theor y Guide . 1.In the Physical M odels tab of the Discr ete Phase M odel dialo g box Figur e 24.3: Discr ete Phase D ialo g Box with DEM C ollision M odel a.Specify the settings y our mo del r equir es under DEM C ollision M odel. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1930Modeling D iscrete Phaseb.(Optional) B y default ,Adaptiv e Collision M esh Width is enabled .This adjusts the width of the c ollision mesh t o the lar gest par cel diamet er multiplied b y the Edge Sc ale F actor. If Adaptiv e Collision M esh Width is disabled , a fix ed Static C ollision M esh Width has t o be giv en in the chosen units of length. c.The Maximum P article Velocity limits the maximum par ticle v elocity to a ph ysically plausible r ange . 2.Set up the injec tion. Setup → Models → Discr ete Phase → Injec tions New... a.In the Set Injec tion P roperties dialo g box, selec t a name fr om the DEM C ollision P artner drop- down list tha t will ser ve as the c ollision par tner . A default name using the par ticle ma terial will b e suggest ed. Note Selec ting none fr om the dr op-do wn list indic ates tha t the par ticles r eleased fr om this injec tion do not par ticipa te in the DEM c ollision c omputa tion. b.If you w ant to use the r olling fr iction c ollision la w (see st ep 4), under the Physical M odels tab , enable Particle Rota tion for those injec tions whose par ticles tak e par t in c ollisions with r olling fr iction. 3.Set the b oundar y conditions f or the discr ete phase as y ou nor mally w ould . If the Boundar y Cond .Type is reflec t, selec t a name fr om the DEM C ollision P artner drop-do wn list t o designa te the c ollision par tner For e xample , in Figur e 24.4: Wall B oundar y Condition f or the DEM M odel (p.1932 ), a w all b oundar y condition will suggest a w all ma terial name , which will designa te the c ollision par tner .The name will ha ve a dem- prefix H owever, if the DEM C ollision P artner is none , the w all will r eflec t par ticles lik e an y other DPM particles using the settings f or the Discr ete Phase Reflec tion C oefficien ts in the Normal and Tangen t directions .These settings gener ally apply f or par ticles tha t are not c olliding acc ording t o DEM, such as massless par ticles . 1931Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Steps f or U sing the D iscrete Phase M odelsFigur e 24.4: Wall B oundar y Condition f or the DEM M odel 4.Define the par ticle in teraction b etween the pairs of the c ollision par tners . a.Click the DEM C ollisions ... butt on a t the b ottom of the Discr ete Phase M odel dialo g box.The DEM Collisions dialo g box (Figur e 24.5: Collision D ialog Box (p.1933 )) will app ear wher e you c an manage the c ollision par tners .You c an Create,Copy,Rename ,Delet e, and List collision par tners .To define collision la ws for a c ollision par tner , selec t a c ollision par tner fr om the Collision P artners list and click the Set... butt on, or simply double-click the c ollision par tner in the list. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1932Modeling D iscrete PhaseFigur e 24.5: Collision D ialo g Box b.In the DEM C ollision S ettings dialo g box (Figur e 24.6: DEM C ollision S ettings D ialog Box (p.1933 )), a list of all the p ossible Collision P airs will e xist. Figur e 24.6: DEM C ollision S ettings D ialo g Box i.Selec t a pair of c ollision par tners fr om the Collision P airs list. ii.For this pair , selec t the Contact Force Laws tha t best descr ibe the c ollision b etween these t wo partners . The Normal contact force laws tha t exist ar e: •spring •spring-dashp ot •her tzian •her tzian-dashp ot You c an also cho ose t o exclude the c ontact force law b y selec ting none . 1933Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Steps f or U sing the D iscrete Phase M odelsFor the Tangen tial contact force law (if c onsider ed), you c an selec t form the f ollowing friction c ollision la ws: •friction-dshf •friction-dshf-r olling (an e xtension of the friction-dshf friction c ollision la w including r olling friction) Each of the la ws is descr ibed in the f ollowing sec tions: •The S pring C ollision La w in the Fluent Theor y Guide •The S pring-D ashp ot C ollision La w in the Fluent Theor y Guide •The H ertzian C ollision La w in the Fluent Theor y Guide •The H ertzian-D ashp ot C ollision La w in the Fluent Theor y Guide •The F riction C ollision La w in the Fluent Theor y Guide •Rolling F riction C ollision La w for DEM in the Fluent Theor y Guide iii.Enter the Constan ts for the chosen Contact Force Laws. Refer to Theor y in the Theor y Guide for guidanc e on ho w to find r easonable v alues of the f orce-law constan ts. iv.Repeat for all other c ollision pairs . v.Click OK or Apply to apply these settings . Note •The choic e of c ollision la ws do es not dep end on the or der in the pair of c ollision par tners . •Failing t o sp ecify a f orce law for a c ollision pair implies tha t respective par ticles will not c ollide . •Rolling fr iction will only b e fac tored in f or a par ticular DEM par ticle injec tion if the Particle Rota tion option is selec ted in the Set Injec tion P roperties dialo g box (Physical P roperties tab). Note For par allel c alcula tions , the DEM c ollision mo del c an b e optimiz ed b y enabling the h ybrid optimiza tion metho d for DPM. This metho d balanc es the load acr oss machines , and , within each machine , the h ybrid par allel DPM metho d is used t o mak e sur e the load is balanc ed b y multi-thr eading . For mor e inf ormation, see the descr iption of the Hybr id Optimiza tion option in the Weigh ting tab discussion in Partitioning (p.3071 ). 24.2.5.13.1. Limitations The f ollowing limita tions cur rently apply when using the DEM c ollision mo del: •Axisymmetr ic geometr y cannot b e used . •Dynamic mesh motion c annot b e used . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1934Modeling D iscrete Phase•The E uler ian w all film mo del c annot b e used . •Shear str ess b oundar y conditions c annot b e used a t walls. •Marangoni str ess b oundar y condition c annot b e used a t walls. •DEM par ticles do not tr ansf er hea t from par ticle t o par ticle dur ing c ontact. 24.2.5.13.2. Numeric R ecommendations To better pr eser ve ener gy dur ing par ticle c ollision, the f ollowing settings in the Numer ics tab ar e recommended and will b e aut oma tically set when DEM C ollisions ar e enabled . 1.Disable Accur acy Control to ensur e tha t DEM time st epping r emains small. 2.Disable Automa ted under Track ing Scheme S elec tion . 3.Selec t implicit from the Track ing Scheme drop-do wn list. Refer to Numer ics f or Tracking of the P articles (p.1939 ) for mor e inf ormation ab out the settings in the Numer ics tab . 24.2.6. User-D efined F unc tions User-defined func tions c an b e used t o cust omiz e the discr ete phase mo del t o include additional b ody forces, mo dify in terphase e xchange t erms (sour ces), calcula te or in tegrate sc alar v alues along the particle tr ajec tory, and inc orporate nonstandar d er osion r ate definitions . More inf ormation ab out user- defined func tions c an b e found in the Fluen t Customiza tion M anual . 1935Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Steps f or U sing the D iscrete Phase M odelsFigur e 24.7: The D iscr ete Phase M odel D ialo g Box and the UDFs In the Discrete Phase M odel D ialog Box (p.3360 ), under User-D efined F unc tions in the UDF tab , ther e are dr op-do wn lists lab eled (see Figur e 24.7: The D iscrete Phase M odel D ialog Box and the UDFs (p.1936 )): •Body Force •Scalar U pdate •Sour ce •Spray Collide F unc tion Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1936Modeling D iscrete Phase•DPM Time S tep •Erosion/A ccretion (if Erosion/A ccretion is enabled under the Physical M odels tab) •Impingemen t Model,Film Regime and Splashing D istribution (if either wall-film is selec ted f or Boundar y Cond .Type in the DPM tab of the Wall dialo g box or the Euler ian Wall F ilm mo del is enabled). Note tha t user-defined Impingemen t Model and S plashing D istribution will o verwrite the impinge- men t/splashing mo del selec ted f or the Lagr angian or E uler ian w all film b oundar y condition. These lists will sho w available user-defined func tions tha t can b e selec ted t o cust omiz e the discr ete phase mo del (see Fluen t Customiza tion M anual for mor e inf ormation). In addition, you c an sp ecify a Numb er of Sc alars which ar e allo cated t o each par ticle and c an b e used to store inf ormation when implemen ting y our o wn par ticle mo dels . 24.2.7. Numer ics of the D iscr ete Phase M odel The under lying ph ysics of the D iscrete Phase M odel is descr ibed b y or dinar y diff erential equa tions (ODE) as opp osed t o the c ontinuous flo w which is e xpressed in the f orm of par tial diff erential equa tions (PDE). Therefore, the D iscrete Phase M odel uses its o wn numer ical mechanisms and discr etiza tion schemes , which ar e complet ely diff erent from other numer ics used in ANSY S Fluen t. 1937Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Steps f or U sing the D iscrete Phase M odelsFigur e 24.8: The D iscr ete Phase M odel D ialo g Box and the N umer ics The Numer ics tab giv es y ou c ontrol o ver the numer ical schemes f or par ticle tr acking as w ell as solutions of hea t and mass equa tions ( Figur e 24.8: The D iscrete Phase M odel D ialog Box and the N umer ics (p.1938 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1938Modeling D iscrete Phase24.2.7.1. Numerics for Track ing of the P articles To solv e equa tions of motion f or the par ticles , the f ollowing numer ical schemes ar e available: implicit uses an implicit E uler in tegration of Equa tion 16.1 in the Theor y Guide which is unc onditionally stable for all par ticle r elaxa tion times . trapezoidal uses a semi-implicit tr apezoidal in tegration. analytic uses an analytic al in tegration of Equa tion 16.1 of the Theor y Guide wher e the f orces ar e held c onstan t during the in tegration. runge-k utta facilita tes a 5th or der R unge K utta scheme der ived b y Cash and K arp [21] (p.4006 ). For additional details , see Solution S trategies f or the D iscrete Phase (p.2022 ). You c an either cho ose a single tr acking scheme , or swit ch b etween higher or der and lo wer or der tracking schemes using an aut oma ted selec tion based on the accur acy to be achie ved and the stabilit y range of each scheme . In addition, you c an c ontrol ho w accur ately the equa tions need t o be solv ed. Accur acy Control enables the solution of equa tions of motion within a sp ecified t oler ance.This is done b y computing the error of the in tegration st ep and r educing the in tegration st ep if the er ror is t oo lar ge. If the er ror is within the giv en t oler ance, the in tegration st ep will also b e incr eased in the ne xt steps. Toler anc e is the maximum r elative error tha t has t o be achie ved b y the tr acking pr ocedur e. Based on the numer ical scheme , diff erent metho ds ar e used t o estima te the r elative error.The implemen ted R unge-K utta scheme uses an emb edded er ror control mechanism. The er ror of the other schemes is c omput ed b y compar ing the r esult of the in tegration st ep with the out come of a t wo step pr ocedur e with half the st ep siz e. Max. Refinemen ts is the maximum numb er of st ep siz e refinemen ts in one single in tegration st ep. If this numb er is e xceeded the in tegration will b e conduc ted with the last r efined in tegration st ep siz e. Automa ted Track ing Scheme S elec tion provides a mechanism t o swit ch in an aut oma ted fashion b etween numer ically stable lo wer or der schemes and higher or der schemes , which ar e stable only in a limit ed r ange . In situa tions wher e the particle is far fr om h ydrodynamic equilibr ium, an accur ate solution c an b e achie ved v ery quick ly with a higher or der scheme , sinc e these schemes need less st ep r efinemen ts for a c ertain t oler ance.When the particle r eaches h ydrodynamic equilibr ium, the higher or der schemes b ecome inefficien t sinc e their step length is limit ed t o a stable r ange . In this c ase, the mechanism swit ches t o a stable lo wer or der scheme and facilita tes lar ger in tegration st eps. Imp ortant This mechanism is only a vailable when Accur acy Control is enabled . 1939Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Steps f or U sing the D iscrete Phase M odelsHigh Or der Scheme can b e chosen fr om the gr oup c onsisting of trapezoidal and runge-k utta scheme . Low Or der Scheme consists of implicit and the e xponen tial analytic integration scheme . Track ing Scheme is selec table only if Automa ted is swit ched off .You c an cho ose an y of the tr acking schemes .You also can c ombine each of the tr acking schemes with Accur acy Control. Note •When DEM C ollisions are enabled , ANSY S Fluen t will aut oma tically set Track ing Scheme to implicit and disable Accur acy Control. •The equa tion f or rotating par ticle motion ( Equa tion 16.217 in the Fluent Theor y Guide ) is solv ed using the E uler implicit discr etiza tion scheme . 24.2.7.2. Including C oupled H eat-M ass S olution E ffec ts on the P articles By default , the par ticle hea t and mass equa tions ar e solv ed in a segr egated manner using an implicit Euler in tegration o ver the time st ep used f or the tr ajec tory calcula tion I f you enable the Coupled Heat-M ass S olution option f or the Droplet ,Combusting , or Multic omp onen t par ticles , ANSY S Fluen t will solv e the c orresponding equa tions using a c oupled ODE solv er with er ror toler ance control. The incr eased accur acy, however, comes a t the e xpense of incr eased c omputa tional time . To ensur e solution accur acy for the Droplet and Multic omp onen t par ticles , ANSY S Fluen t will aut o- matically swit ch t o the c oupled algor ithm dur ing the in tegration time st ep when the e vaporated mass is gr eater than the limiting mass change (defined in Equa tion 24.4 (p.1940 )), or when the particle t emp erature change is gr eater than the limiting t emp erature change (defined in Equa- tion 24.5 (p.1940 )). (24.4) wher e is the par ticle mass (k g) and is the v aporization limiting fac tor for the mass . (24.5) wher e is the par ticle t emp erature (K), is the bulk t emp erature (K), and is the v aporization limiting fac tor for the t emp erature. You will en ter the Vaporization Limiting F actors for Mass and Heat .The default v alues of 0.3 and 0.1 ha ve been det ermined b y sy stema tic t esting and ar e recommended f or c omputa tions . 24.2.7.3. Track ing in a R efer enc e Frame Particle tr acking is r elated t o a c oordina te sy stem. With Track in A bsolut e Frame enabled , you c an choose t o track the par ticles in the absolut e reference frame . All par ticle c oordina tes and v elocities are then c omput ed in this fr ame .The f orces due t o friction with the c ontinuous phase ar e transf ormed to this fr ame aut oma tically. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1940Modeling D iscrete PhaseIn rotating flo ws it migh t be appr opriate for numer ical reasons t o track the par ticles in the r elative reference frame . If several reference frames e xist in one simula tion, then the par ticle v elocities ar e transf ormed t o each r eference frame when the y en ter the fluid z one asso ciated with this r eference frame . When the impac t of par ticles with w alls in multiple r otating r eference frames is imp ortant, as it is the case with a r otating imp eller in a sta tionar y baffled tank, it is nec essar y to mo del the flo w as a sliding mesh simula tion. 24.2.7.4. Node B ased A veraging of P article D ata In gener al, the pr esenc e of DPM par cels ma y aff ect the c ontinuous phase fluid flo w meaning tha t discr ete phase sour ce terms and par ticle da ta such as fluid dr ag, temp erature, volume fr action, and velocity can b e in tegrated in to the flo w solv er. By default in ANSY S Fluen t, the eff ects of a par ticular DPM par cel ar e applied only t o the c ells tha t intersec t with the tr ajec tory of tha t par cel. As an alt ern- ative,Enable N ode B ased A veraging is off ered which distr ibut es the eff ects of a DPM par cel even into neighb oring c ells tha t shar e at least a mesh no de with the c ells in tersec ted b y the tr ajec tory. This allo ws a r educ tion of gr id dep endenc y of DPM simula tions , sinc e each par cel’s eff ects on the flow solv er ar e distr ibut ed mor e smo othly acr oss neighb oring c ells. You c an selec t Enable N ode B ased A veraging in the Numer ics tab of the Discr ete Phase M odel dialo g box, as sho wn in Figur e 24.8: The D iscrete Phase M odel D ialog Box and the N umer ics (p.1938 ). For non-DDPM c ases , the Enable N ode B ased A veraging option is not a vailable when the Linear ize Sour ce Terms is selec ted. When enabled , the no de based a veraging is applied t o par ticle v elocity, par ticle t emp erature, par ticle volume fr action, and DPM c oncentration. By default ,Average DPM S our ce Terms is also enabled , which applies no de a veraging t o the sour ce terms as w ell.When the D ense D iscrete Phase M odel is being used , the Average DDPM Variables option app ears t o pr ovide no de based a veraging f or the discr ete phase sp ecific v ariables , such as DDPM par ticle dr ag.When Contour P lots f or DPM Variables is enabled ( Reporting of D iscrete Phase Variables (p.2050 )), these quan tities will also b e no de a veraged . Average in E ach In tegration S tep should b e enabled if y ou find tha t the flux r eport is sho wing dis- crepancies f or mass flo w rates of par ticles injec ted in to and lea ving the domain. This option incr eases computa tion time so it is not enabled b y default. Onc e you ha ve selec ted Enable N ode B ased A veraging , you must also selec t the Averaging K ernel to accumula te the par ticle r elated da ta on the mesh no des and t o redistr ibut e them back t o the finit e volume c ells.The k ernel and r elated settings ar e sp ecified in the Kernel S ettings sec tion of the Dis- crete Phase M odel dialo g box.The f ollowing k ernels ar e available: •nodes-p er-c ell •shor test-distanc e •inverse-distanc e •gaussian If you use the gaussian kernel, you must also sp ecify the Gaussian F actor, which det ermines the width of the G aussian distr ibution. The default v alue is 1. For details ab out the a veraging and k ernel equa tions , refer to Node B ased A veraging in the Theor y Guide . 1941Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Steps f or U sing the D iscrete Phase M odels24.2.7.5. Lineariz ed S our ce Terms Source terms f or discr ete phase momen tum, ener gy, and sp ecies c an b e linear ized with r espect to the c ell v ariable , : (24.6) This linear ization str ongly incr eases numer ical stabilit y for st eady flo ws. For tr ansien t flo ws, it typic ally allows the use of lar ger time st eps and lar ger under-r elaxa tion fac tors f or the DPM mo del. You c an enable sour ce term linear ization with the Linear ize Sour ce Terms option in the Numer ics tab of the Discr ete Phase M odel dialo g box. For non-DDPM c ases , the Linear ize Sour ce Terms option is not a vailable when the Enable N ode B ased A veraging is selec ted. The sour ce term linear ization c an b e combined with the Update DPM S our ces E very Flow Iteration option ( Options f or In teraction with the C ontinuous P hase (p.1918 )). 24.2.7.6. Staggering of P articles in Spac e and Time In or der t o obtain a b etter represen tation of an injec tor, the par ticles c an b e stagger ed spa tially and/or temp orally.When par ticles ar e stagger ed spa tially , ANSY S Fluen t randomly samples fr om the r egion in which the spr ay is sp ecified (f or e xample , the sheet thick ness in the pr essur e-swir l atomiz er) so that as the c alcula tion pr ogresses , trajec tories will or igina te from the en tire region. This allo ws the entire geometr y sp ecified in the a tomiz er to be sampled while sp ecifying f ewer str eams in the input dialo g box, thus decr easing c omputa tional e xpense . You c an enable injec tion-sp ecific spa tial stagger ing of the par ticles b y selec ting the Stagger P ositions option in the Stagger Options group b ox in the Point Properties tab of the Set Injec tion P roperties dialo g box and then, if applic able , specifying Stagger R adius to define the r egion fr om which par ticles are released . For mor e inf ormation, see the appr opriate sec tions f or injec tion-sp ecific p oint properties. You c an also enable injec tion-sp ecific spa tial stagger ing of the par ticles b y issuing the f ollowing t ext commands: •/define/models/dpm/options/stagger-spatially-atomizer-injections? •/define/models/dpm/options/stagger-spatially-standard-injections? When spa tial stagger ing is enabled f or non-a tomiz er injec tions , a stagger r adius must b e sp ecified by using the t ext command: /define/models/dpm/options/stagger-radius When injec ting par ticles in a tr ansien t calcula tion using r elatively lar ge time st eps in r elation t o the spray event, the par ticles c an clump t ogether in discr ete bunches .The clumps do not lo ok ph ysically realistic , though ANSY S Fluen t calcula tes the tr ajec tory for each par ticle as it passes thr ough a c ell and the c oupling t o the gas phase is pr operly acc oun ted f or.To obtain a sta tistic ally smo other r ep- resen tation of the spr ay, the par ticles c an b e stagger ed in time . During the first time st ep, the par ticle is tr acked f or a r andom p ercentage of its initial st ep.This r esults in a sample of the initial v olume swept out b y the par ticle dur ing the first time st ep and a smo other , mor e unif orm spa tial distr ibution at longer time in tervals. The f ollowing setup c ommands f or stagger ing in time ar e available in the t ext user in terface (TUI): •stagger-temporally? Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1942Modeling D iscrete Phase•staggering-factor The “stagger ing fac tor” is applied t o temp oral stagger ing only . It is a c onstan t tha t multiplies the time step siz e to giv e the r andom sampling in terval.The stagger ing fac tor c ontrols the p ercentage of e very particle ’s initial time st ep tha t will b e sampled . For e xample , if the stagger ing fac tor is 0.5, then the parcels in the injec tion will b e tracked b etween half and all of their full initial time st ep. If the stag- gering fac tor is 0.1, then the par cels will b e tracked b etween ninet y percent and all of their initial time st ep. If the stagger ing fac tor is set t o 0.9, the par cels will b e tracked b etween t en p ercent and all of their initial time st ep.This allo ws you t o control the amoun t of smo othing b etween injec tions . The default v alues f or the options in the TUI ar e spa tial stagger ing f or a tomiz ers (including the solid- cone), no t emp oral stagger ing and a t emp oral stagger ing fac tor of 1.0. The t emp oral stagger ing fac tor is inac tive un til the flag f or temp oral stagger ing is enabled . 24.2.7.7. Under -Relaxing L agr angian Wall F ilm H eight As the w all film mo ves and spr eads on the w all fac es, under-r elaxa tion is applied t o the film heigh t computa tion. The under-r elaxa tion fac tor c an b e sp ecified using the f ollowing t ext command: define/models/dpm/numerics/underrelax-film-height A lo wer under-r elaxa tion fac tor results in a smo other film app earance, esp ecially closer t o the film edge . However, it ma y dist ort the film shap e, esp ecially f or c ases wher e high v elocity dr oplets ar e impinging on the film. The r ecommended v alues r ange b etween 0.5 (default) and 0.9. 24.3. Setting Initial C onditions f or the D iscr ete Phase The pr imar y inputs tha t you must pr ovide f or the discr ete phase c alcula tions in ANSY S Fluen t are the initial c onditions tha t define the star ting p ositions , velocities , and other par amet ers f or each par ticle stream and the ph ysical eff ects ac ting on the par ticle str eams , requir ing additional par ticle pr operties. You will define the initial c onditions f or a par ticle/dr oplet str eam b y creating an “injec tion ” and assigning properties t o it. The r equir ed initial c onditions dep end on the injec tion t ype, while the ph ysical eff ects ar e selec ted b y choosing an appr opriate par ticle t ype. For some injec tion t ypes y ou c an pr ovide a par ticle siz e distr ibu- tion, like the R osin-R ammler distr ibution, see Using the R osin-R ammler D iamet er D istribution M eth- od (p.1963 ). The initial c onditions pr ovide the star ting v alues f or all of the dep enden t discr ete phase v ariables tha t descr ibe the instan taneous c onditions of an individual par ticle , and include the f ollowing: •position ( , , coordina tes) of the par ticle •velocities ( , , ) of the par ticle Velocity magnitudes and spr ay cone angle c an also b e used (in 3D) t o define the initial v elocities (see Point Properties f or C one Injec tions (p.1950 )). For mo ving r eference frames , relative velocities should be sp ecified . •diamet er of the par ticle , •temp erature of the par ticle , 1943Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting Initial C onditions f or the D iscrete Phase•mass flo w rate of the par ticle str eam tha t will f ollow the tr ajec tory of the individual par ticle/dr oplet , (requir ed only f or coupled c alcula tions) •additional par amet ers if one of the a tomiz er mo dels descr ibed in Atomiz er M odel Theor y in the Theor y Guide is used f or the injec tion Imp ortant When an a tomiz er mo del is selec ted, you will not sp ecify initial diamet er, velocity, and position quan tities f or the par ticles due t o the c omple xities of sheet and ligamen t breakup. Instead of initial c onditions , the quan tities y ou will sp ecify f or the a tomiz er mo dels ar e global par amet ers. These dep enden t variables (t emp erature, diamet er, and so on) ar e up dated acc ording t o the equa tions of motion ( Particle M otion Theor y in the Theor y Guide ) and acc ording t o the hea t/mass tr ansf er relations applied ( Laws for H eat and M ass Ex change in the Theor y Guide ) as the par ticle/dr oplet mo ves along its tr ajec tory.You c an define an y numb er of diff erent sets of initial c onditions f or discr ete phase particles/dr oplets pr ovided tha t your c omput er has sufficien t memor y. For the setup of tr ansien t par ticle c ases , the p oint properties f or mass flo w and v elocity can b e sp ecified using tr ansien t profiles (see Point Properties f or Transien t Injec tions (p.1984 )). For additional inf ormation, see the f ollowing sec tions: 24.3.1. Injec tion Types 24.3.2. Particle Types 24.3.3. Point Properties f or Single Injec tions 24.3.4. Point Properties f or G roup Injec tions 24.3.5. Point Properties f or C one Injec tions 24.3.6. Point Properties f or Sur face Injec tions 24.3.7. Point Properties f or P lain-Or ifice Atomiz er Injec tions 24.3.8. Point Properties f or P ressur e-Swirl Atomiz er Injec tions 24.3.9. Point Properties f or A ir-Blast/A ir-Assist A tomiz er Injec tions 24.3.10. Point Properties f or Flat-Fan A tomiz er Injec tions 24.3.11. Point Properties f or Effervescent Atomiz er Injec tions 24.3.12. Point Properties f or File Injec tions 24.3.13. Point Properties f or C ondensa te Injec tions 24.3.14. Using the R osin-R ammler D iamet er D istribution M etho d 24.3.15. Creating and M odifying Injec tions 24.3.16. Defining Injec tion P roperties 24.3.17. Specifying Injec tion-S pecific P hysical M odels 24.3.18. Specifying Turbulen t Dispersion of P articles 24.3.19. Custom P article La ws 24.3.20. Defining P roperties C ommon t o More than One Injec tion 24.3.21. Point Properties f or Transien t Injec tions 24.3.1. Injec tion Types ANSY S Fluen t provides 11 t ypes of injec tions: •single Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1944Modeling D iscrete Phase•group •cone (only in 3D) •surface •plain-or ifice atomiz er •pressur e-swir l atomiz er •air-blast-a tomiz er •flat-fan-a tomiz er •effervescent-atomiz er •file •condensa te For each nona tomiz er injec tion t ype, you will sp ecify each of the initial c onditions list ed in Setting Initial C onditions f or the D iscrete Phase (p.1943 ), the t ype of par ticle tha t possesses these initial c onditions , and an y other r elevant par amet ers f or the par ticle t ype chosen. When defining injec tion p oint properties f or the f ollowing injec tion t ypes: •single •group •all c one injec tions •all a tomiz er injec tions you c an in teractively pr eview the cur rent injec tion p osition and or ientation in the gr aphics windo w prior t o sa ving the settings .When y ou click Update Injec tion D ispla y in the Set Injec tion P roperties dialo g box or Set M ultiple Injec tion P roperties dialo g box, ANSY S Fluen t will apply the cur rent settings to the injec tion displa y. Onc e you click OK in the Set Injec tion P roperties dialo g box or Apply in the Set M ultiple Injec tion P roperties dialo g box, the injec tion pr operties will b e sa ved, and the gr aphics windo w will b e onc e mor e up dated.When y ou op en the Set Injec tion P roperties dialo g box for the existing injec tion, ANSY S Fluen t will also aut oma tically displa y the injec tion in the gr aphics windo w. The injec tion p osition and or ientation will not b e displa yed if y ou use pr ofiles t o sp ecify the injec tion position and dir ection. If you use the DEFINE_DPM_INJECTION_INIT user-defined func tion, the displa yed injec tion p osition and or ientation will r eflec t only the default p oint properties f or the sp ecific injec tion t ype. You should cr eate a single injec tion when y ou w ant to sp ecify a single v alue f or each of the initial conditions ( Figur e 24.9: Particle Injec tion D efining a S ingle P article S tream (p.1946 )). Create a gr oup in- jection ( Figur e 24.10: Particle Injec tion D efining an Initial S patial D istribution of the P article Streams (p.1946 )) when y ou w ant to define a r ange f or one or mor e of the initial c onditions (f or e xample , a range of diamet ers or a r ange of initial p ositions). To define c one injec tions in 3D pr oblems , create a cone injec tion and sp ecify a par ticle r elease pa ttern (p oint, hollo w, ring, or solid) ( Figur e 24.11: Particle Injec tion D efining an Initial S pray Distribution of the P article Velocity (p.1946 )).To release par ticles fr om a sur face (either a z one sur face or a sur face you ha ve defined using Create in the Domain ribbon tab 1945Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting Initial C onditions f or the D iscrete Phase(Surfacegroup b ox)), you will cr eate a sur face injec tion. (If you cr eate a sur face injec tion, a par ticle stream will b e released fr om each fac et of the sur face.You c an use the Bounded and Sample P oints options in the Plane S urface dialo g box to cr eate injec tions fr om a r ectangular mesh of par ticles in 3D (see Plane Sur faces (p.2742 ) for details). If you ar e mo deling film c ondensa tion, use the condensa te injec tion t ype to define the v apor-liquid ma terial pair and other mo deling settings f or the film c on- densa tion pr ocess. Figur e 24.9: Particle Injec tion D efining a S ingle P article S tream Figur e 24.10: Particle Injec tion D efining an Initial S patial D istribution of the P article S treams Figur e 24.11: Particle Injec tion D efining an Initial S pray D istribution of the P article Velocity Particle initial c onditions (p osition, velocity, diamet er, temp erature, and mass flo w rate) can also b e read fr om an e xternal file if none of the injec tion t ypes list ed ab ove can b e used t o descr ibe your in- jection distr ibution. The inputs f or setting injec tions ar e descr ibed in detail in Defining Injec tion P roperties (p.1969 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1946Modeling D iscrete Phase24.3.2. Particle Types When y ou define a set of initial c onditions (as descr ibed in Defining Injec tion P roperties (p.1969 )), you will need t o sp ecify the t ype of par ticle .The par ticle t ypes a vailable t o you dep end on the r ange of physical mo dels tha t you ha ve defined . •A massless par ticle is a discr ete elemen t tha t follows the flo w and t emp erature of the c ontinuous phase . As it has no mass , it has no asso ciated ph ysical pr operties, and no f orce is e xerted on it. However, you c an assign a U ser-D efined La w to be applied t o the massless par ticle .The massless par ticle t ype is a vailable with all ANSY S Fluen t mo dels . •An iner t par ticle is a discr ete phase elemen t (par ticle , droplet , or bubble) tha t ob eys the f orce balanc e (Equa tion 16.1 in the Theor y Guide ) and is subjec t to hea ting or c ooling via La w 1 ( Iner t Heating or C ooling (Law 1/La w 6) in the Theor y Guide ).The iner t type is a vailable f or all ANSY S Fluen t mo dels . •A droplet par ticle is a liquid dr oplet in a c ontinuous-phase gas flo w tha t ob eys the f orce balanc e (Equa- tion 16.1 in the Theor y Guide ) and tha t experienc es hea ting/c ooling via La w 1 f ollowed b y vaporization and b oiling via La ws 2 and 3 ( Droplet Vaporization (La w 2) and Droplet B oiling (La w 3) in the Theor y Guide ). The dr oplet t ype is a vailable when hea t transf er is b eing mo deled and a t least t wo chemic al sp ecies ar e active or the non-pr emix ed or par tially pr emix ed c ombustion mo del is ac tive.You should use the ideal gas law to define the gas-phase densit y (in the Create/Edit M aterials dialo g box, as discussed in Densit y Inputs for the Inc ompr essible Ideal G as La w (p.1104 )) when y ou selec t the dr oplet t ype. •A combusting par ticle is a solid par ticle tha t ob eys the f orce balanc e (Equa tion 16.1 ), and , after an initial phase of iner t hea ting (La w 1), under goes de volatization ( Devolatiliza tion (La w 4) ) and then a het erogeneous surface reaction via La w 5 ( Surface Combustion (La w 5) in the Theor y Guide ). Finally , the non volatile p ortion of a c ombusting par ticle is subjec t to iner t hea ting via La w 6. You c an also include an e vaporating ma terial with the c ombusting par ticle b y selec ting the Wet C ombustion option in the Set Injec tion P roperties Dialog Box (p.3917 ).This allo ws you t o include a ma terial tha t evaporates and b oils via La ws 2 and 3 ( Droplet Vaporization (La w 2) and Droplet B oiling (La w 3) in the Theor y Guide ) before de volatiliza tion of the par ticle material b egins .The c ombusting t ype is a vailable when hea t transf er is b eing mo deled and a t least thr ee chemic al sp ecies ar e ac tive or the non-pr emix ed c ombustion mo del is ac tive.You should use the ideal gas law to define the gas-phase densit y (in the Create/Edit M aterials D ialog Box (p.3386 )) when y ou selec t the combusting par ticle t ype. •A multic omp onen t par ticle is , as the name implies , a dr oplet par ticle c ontaining a mix ture of se veral comp onen ts or sp ecies .The c onser vation equa tions of all c omp onen ts, the ener gy equa tion, and v apor- liquid-equilibr ium a t the multic omp onen t par ticle sur face form a c oupled sy stem of diff erential equa tions . Law 7, the multic omp onen t law (Multic omp onen t Particle D efinition (La w 7) in the Theor y Guide ) is used for such sy stems .You should use the v olume w eigh ted mixing la w to define the par ticle mix ture densit y (in the Create/Edit M aterials D ialog Box (p.3386 )) when y ou selec t the par ticle-mix ture ma terial type. Laws ActivatedDescr iption Particle Type – – Massless 1, 6 iner t/hea ting or c ooling Iner t 1, 2, 3, 6 heating/e vaporation/b oiling Droplet 1, 4, 5, 6 heating; evolution of v olatiles/sw elling; het erogeneous sur face reaction Combusting 7 multic omp onen t droplets/par ticles Multic omp onen t 1947Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting Initial C onditions f or the D iscrete Phase24.3.3. Point Properties f or S ingle Injec tions For a single injec tion, you will define the f ollowing initial c onditions f or the par ticle str eam under the Point Properties heading (in the Set Injec tion P roperties D ialog Box (p.3917 )): •position Set the , , and positions of the injec ted str eam along the C artesian ax es of the pr oblem geometr y in the X-,Y-, and Z-Position fields . (Z-Position will app ear only f or 3D pr oblems .) •velocity Set the , , and comp onen ts of the str eam ’s initial v elocity in the X-,Y-, and Z-Velocity fields . (Z-Velocity will app ear only f or 3D pr oblems .) •angular v elocity (available when par ticle r otation is enabled (see Particle R otation (p.1974 ))) Set the , , and comp onen ts of the str eam ’s initial v elocity in the X-,Y-, and Z-A ngular-V elocity fields . (Only Z-A ngular-V elocity will app ear f or 2D pr oblems , because r otation in 2D o ccurs in the plane , tha t is, the r otation v ector is nor mal t o the plane .) •diamet er Set the initial diamet er of the injec ted par ticle str eam in the Diamet er field . •temp erature Set the initial (absolut e) temp erature of the injec ted par ticle str eam in the Temp erature field . •mass flo w rate For c oupled phase c alcula tions (see Solution S trategies f or the D iscrete Phase (p.2022 )), set the mass of par ticles p er unit time tha t follows the tr ajec tory defined b y the injec tion in the Flow R ate field . Note tha t in axisymmetr ic pr oblems the mass flo w rate is defined p er radians and in 2D pr oblems per unit met er depth (r egar dless of the r eference value f or length). •duration of injec tion For unst eady par ticle tr acking (see Steady/Transien t Treatmen t of P articles (p.1918 )), set the star ting and ending time f or the injec tion in the Start Time and Stop Time fields .When In-C ylinder mesh motion is enabled , set the star ting and ending cr ank angles f or the injec tion in the Start Crank Angle and Stop C rank A ngle fields .The v alues y ou en ter ar e for one c omplet e engine c ycle. In subsequen t cycles, the injec tion will b e star ted and st opp ed acc ording t o Equa tion 11.30 (p.1339 ), wher e corresponds t o the injec tion star t or end cr ank angle . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1948Modeling D iscrete PhaseFor the massless par ticle t ype, you will only need t o define the p osition of the injec tion. The par ticle injec tion v elocity is set b y the solv er equal t o the v elocity of the c ontinuous phase a t the injec tion point. If you w ant to randomly distr ibut e the initial plac emen t of the par ticles , you c an enable Stagger P os- itions and sp ecify Stagger R adius to define the par ticle r elease r egion. For mor e inf ormation on spatial stagger ing, see Stagger ing of P articles in S pace and Time (p.1942 ).This option is disabled b y default. 24.3.4. Point Properties f or G roup Injec tions For gr oup injec tions , you will define the pr operties p osition, velocity, angular v elocity (available when particle r otation is enabled (see Particle R otation (p.1974 ))), diamet er, temp erature, and flo w rate for the First P oint and Last P oint in the gr oup .That is, you will define a r ange of v alues , through , for each initial c ondition by setting v alues f or and . ANSY S Fluen t assigns a v alue of to the th injec tion in the gr oup using a linear v ariation b etween the first and last v alues f or : (24.7) Thus, for e xample , if y our gr oup c onsists of 5 par ticle str eams and y ou define a r ange f or the initial location fr om 0.2 t o 0.6 met ers, the initial location of each str eam is as f ollows: •Stream 1: = 0.2 met ers •Stream 2: = 0.3 met ers •Stream 3: = 0.4 met ers •Stream 4: = 0.5 met ers •Stream 5: = 0.6 met ers Imp ortant In gener al, you should supply a r ange f or only one of the initial c onditions in a giv en group—lea ving all other c onditions fix ed while a single c ondition v aries among the str eam numb ers of the gr oup . Other wise y ou ma y find , for e xample , tha t your simultaneous inputs of a spa tial distr ibution and a siz e distr ibution ha ve plac ed the small dr oplets a t the b egin- ning of the spa tial r ange and the lar ge dr oplets a t the end of the spa tial r ange . 1949Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting Initial C onditions f or the D iscrete PhaseThe sp ecified flo w rate is defined p er par ticle str eam and c an also b e in terpolated using Equa- tion 24.7 (p.1949 ).When a R osin-R ammler siz ed distr ibution is sp ecified the t otal flo w rate will b e sp ecified . For the massless par ticle t ype, you will only need t o define the first and last p oint of the injec tion group p osition. The par ticle v elocities ar e set b y the solv er equal t o the v elocity of the c ontinuous phase a t the injec tion p oints. Note tha t you c an use a diff erent metho d for defining the siz e distr ibution of the par ticles , as discussed below. To randomly distr ibut e the initial plac emen t of the par ticles , enable Stagger P ositions and sp ecify Stagger R adius to define the par ticle r elease r egion. For mor e inf ormation on spa tial stagger ing, see Stagger ing of P articles in S pace and Time (p.1942 ).This option is disabled b y default. 24.3.5. Point Properties f or C one Injec tions In 3D pr oblems , you c an define the f ollowing t ypes of par ticle str eam c ones: •point-cone •hollo w-c one •ring-c one •solid-c one The par ticles ar e released fr om a 2D r egion tha t ma y be a p oint, a cir cle, or an annulus . Its geometr y, location, and or ientation as w ell as the shap e of the spr ay cone ar e defined b y the injec tion par amet ers. Onc e you selec t a c one injec tion t ype from the Cone Type drop-do wn list , (the Cone Injec tor P ara- met ers group b ox in the Point Properties tab of the Set Injec tion P roperties dialo g box), the par a- met ers sp ecific t o the selec ted injec tion t ype will b e displa yed.These inputs ar e summar ized b elow. Refer to Figur e 24.12: Cone Injec tor G eometr y (p.1951 ) for an illustr ation of the geometr y. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1950Modeling D iscrete PhaseFigur e 24.12: Cone Injec tor G eometr y •position Set the c oordina tes of the or igin of the spr ay cone in the X-,Y-, and Z-Position fields ( in Fig- ure 24.12: Cone Injec tor G eometr y (p.1951 )) •diamet er Set the diamet er of the par ticles in the str eam in the Diamet er field . •temp erature Set the t emp erature of the str eams in the Temp erature field . •duration of injec tion For unst eady par ticle tr acking (see Steady/Transien t Treatmen t of P articles (p.1918 )), set the star ting and ending time f or the injec tion in the Start Time and Stop Time fields .When In-C ylinder mesh motion is enabled , set the star ting and ending cr ank angles f or the injec tion in the Start Crank Angle and Stop C rank A ngle fields . •axis Set the , , and comp onen ts of the v ector defining the c one’s axis in the X-A xis,Y-A xis, and Z- Axis fields . ( in Figur e 24.12: Cone Injec tor G eometr y (p.1951 )) •velocity 1951Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting Initial C onditions f or the D iscrete PhaseSet the v elocity magnitude of the par ticle str eams tha t will b e or iented along the sp ecified spr ay cone in the Velocity M agnitude field . ( in Figur e 24.12: Cone Injec tor G eometr y (p.1951 )) Note This is the t otal spr ay velocity magnitude and includes an y swir l comp onen t in a hollo w cone injec tor. •angular v elocity Set the angular v elocity magnitude of the par ticle str eams tha t will b e or iented along the sp ecified spray cone in the Angular Velocity M agnitude field . •cone angle Set the included half-angle of the spr ay cone in the Cone A ngle field . ( in Figur e 24.12: Cone In- jector G eometr y (p.1951 )) •radii For hollo w-c one ,ring-c one , and solid-c one injec tions , specify the Out er R adius . For ring-c one injec tions , specify a nonz ero Inner R adius to mo del injec tors tha t do not emana te from a single p oint.The par ticles will b e distr ibut ed ab out the axis with the sp ecified r adius . ( in Figur e 24.12: Cone Injec tor G eometr y (p.1951 )) •swir l fraction (hollo w cone only) Set the swir l fraction, which det ermines the r elative magnitude of the swir l velocity, in the Swirl Fraction field . The dir ection of the swir l comp onen t is defined using the r ight-hand r ule ab out the c one axis (a nega tive value f or the swir l fraction c an b e used t o reverse the swir l dir ection). •mass flo w rate For c oupled c alcula tions , set the t otal mass flo w rate for the str eams in the spr ay cone in the Total Flow R ate field . Note tha t for a 3D sec tor, the flo w rate must b e appr opriate for the sec tor defined by the Azimuthal S tart Angle and Azimuthal S top A ngle . •azimuthal angles For 3D sec tors, set the Azimuthal S tart Angle and Azimuthal S top A ngle to define the sec tor. ( and , respectively, in Figur e 24.12: Cone Injec tor G eometr y (p.1951 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1952Modeling D iscrete PhaseThe Azimuthal S tart Angle and Azimuthal S top A ngle are sp ecified with r espect to a r eference vector, , tha t is or thogonal t o both the c one axis and the global X axis .The r eference vector, , can b e det ermined as the cr oss pr oduc t of the c one axis and the global X axis . wher e is a unit v ector along the global X axis . In the c ase tha t the c one axis is along the X axis , then is along the Y axis . In addition t o the ab ove par amet ers, you c an selec t the f ollowing options: •Uniform M assflo w D istribution (solid-c one or ring-c one ): Specifies a unif orm spacial distr ibution of mass over the cr oss-sec tion of a c one .This is esp ecially imp ortant when the mesh c ell siz e is smaller than the particle diamet er or another char acteristic siz e.This option is enabled b y default. •Stagger P ositions : Specifies a r andom spa tial distr ibution of par ticle st eams . For hollo w-c one injec tions you must also sp ecify Stagger R adius to define the r egion o ver which par ticle r elease p oints ar e stagger ed in spac e. For mor e inf ormation on spa tial stagger ing, see Stagger ing of P articles in S pace and Time (p.1942 ). This option is disabled b y default. The distr ibution of the v elocity dir ections in the par ticle str eams f or the p oint-cone , ring-c one , and solid-c one injec tions is r andom. Further mor e, duplic ating this injec tion ma y not nec essar ily result in the same distr ibution, at the same lo cation. Imp ortant For tr ansien t calcula tions , the spa tial distr ibution of str eams a t the initial injec tion lo cation is recalcula ted a t each time st ep. Sampling diff erent possible tr ajec tories allo ws a mor e ac- curate represen tation of a p oint, ring, or solid c one using f ewer computa tional par cels. For steady-sta te calcula tions , the tr ajec tories ar e initializ ed one time and k ept the same f or subsequen t DPM it erations .The tr ajec tories ar e recalcula ted when a change in the Injec tions dialo g box occurs or when a c ase and da ta file ar e sa ved. If the r esiduals and solution change when a small change is made t o the injec tion or when a c ase and da ta file ar e sa ved, it ma y mean tha t ther e ar e not enough tr ajec tories b eing used t o represen t the p oint, ring, or solid c one with sufficien t accur acy. Note tha t you ma y want to define multiple spr ay cones emana ting fr om the same initial lo cation in order t o sp ecify a k nown siz e distr ibution of the spr ay or t o include a k nown r ange of c one angles . For the massless par ticle t ype, you will only need t o define p osition, axis , cone angle , azimuthal angles , and r adius .The par ticle v elocities ar e set b y the solv er equal t o the v elocity of the c ontinuous phase at the injec tion p oints. 24.3.6. Point Properties f or S urface Injec tions For sur face injec tions , you will define all the pr operties descr ibed in Point Properties f or S ingle Injec- tions (p.1948 ) for single injec tions e xcept f or the initial p osition of the par ticle str eams .The initial p ositions of the par ticles will b e the lo cation of the da ta p oints on the sp ecified sur face(s). Note tha t you will set the Total F low R ate of all par ticles r eleased fr om the sur face (requir ed f or c oupled c alcula tions only). If you w ant, you c an sc ale the individual mass flo w rates of the par ticles b y the r atio of the ar ea of the fac e the y are released fr om t o the t otal ar ea of the sur face.To sc ale the mass flo w rates, selec t the Scale F low R ate By Face Area option under Point Properties . For the massless par ticle t ype, you 1953Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting Initial C onditions f or the D iscrete Phasewill not need t o en ter an y inf ormation t o define a sur face injec tion. The par ticle v elocities ar e set b y the solv er equal t o the v elocities of the c ontinuous phase a t the injec tion p oints. Note tha t man y sur faces ha ve nonunif orm distr ibutions of p oints. If you w ant to gener ate a unif orm spatial distr ibution of par ticle str eams r eleased fr om a sur face in 3D , you c an cr eate a b ounded plane surface with a unif orm distr ibution using the Plane Sur face Dialog Box (p.3895 ), as descr ibed in Plane Surfaces (p.2742 ). In 2D , you c an cr eate a r ake using the Line/R ake Sur face Dialog Box (p.3847 ), as descr ibed in Line and R ake Sur faces (p.2738 ). In addition t o the option of sc aling the flo w rate by the fac e ar ea, the nor mal dir ection of a fac e can be used f or the injec tion dir ection. To use the fac e nor mal dir ection f or the injec tion dir ection, selec t the Injec t Using F ace Normal D irection option under Point Properties (Figur e 24.19: Setting Sur face Injec tion P roperties (p.1971 )). Onc e this option is selec ted, you only need t o sp ecify the v elocity magnitude of the injec tion, not the individual c omp onen ts of the v elocity magnitude . Imp ortant •Only sur face injec tions fr om b oundar y sur faces will b e mo ved with the mesh when a sliding mesh or a mo ving or def orming mesh is b eing used . •For mo ving or def orming mesh simula tions , only z onal sur faces c an b e selec ted. A nonunif orm siz e distr ibution c an b e used f or sur face injec tions , as descr ibed b elow. 24.3.6.1. Using the R osin-R ammler D iamet er D istribution Metho d The R osin-R ammler siz e distr ibutions descr ibed in Using the R osin-R ammler D iamet er D istribution Metho d (p.1963 ) for gr oup injec tions is also a vailable f or sur face injec tions . If you selec t one of the Rosin-R ammler distr ibutions ( rosin-r ammler or rosin-r ammler-lo garithmic ), you will need t o sp ecify the f ollowing par amet ers under Point Properties , in addition t o the initial v elocity, temp erature, and total flo w rate: •Min. Diamet er This is the smallest diamet er to be consider ed in the siz e distr ibution. •Max. Diamet er This is the lar gest diamet er to be consider ed in the siz e distr ibution. •Mean D iamet er This is the siz e par amet er, , in the R osin-R ammler equa tion ( Equa tion 24.9 (p.1963 )). •Spread P aramet er This is the e xponen tial par amet er, , in Equa tion 24.9 (p.1963 ). •Numb er of D iamet ers This is the numb er of diamet ers in each distr ibution (tha t is, the numb er of diff erent diamet ers in the str eam injec ted fr om each fac e of the sur face). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1954Modeling D iscrete PhaseANSY S Fluen t will injec t str eams of par ticles fr om each fac e on the sur face, with diamet ers defined by the R osin-R ammler distr ibution func tion. The t otal numb er of injec tion str eams tr acked f or the surface injec tion will b e equal t o the numb er of diamet ers in each distr ibution ( Numb er of D iamet ers) multiplied b y the numb er of fac es on the sur face. 24.3.7. Point Properties f or P lain-Or ifice Atomiz er Injec tions For a plain-or ifice atomiz er injec tion, you will define the f ollowing initial c onditions under Point Properties : •position Set the , , and positions of the injec ted str eam along the C artesian ax es of the pr oblem geometr y in the X-Position ,Y-Position , and Z-Position fields . (Z-Position will app ear only f or 3D pr oblems). •axis (3D only) Set the , , and comp onen ts of the v ector defining the axis of the or ifice in the X-A xis,Y-A xis, and Z-A xis fields . •temp erature Set the t emp erature of the str eams in the Temp erature field . •mass flo w rate Set the t otal mass flo w rate for the str eams in the a tomiz er in the Flow R ate field . Note tha t in 3D sectors, the flo w rate must b e appr opriate for the sec tor defined b y the Azimuthal S tart Angle and Azimuthal S top A ngle . •duration of injec tion For unst eady par ticle tr acking (see Steady/Transien t Treatmen t of P articles (p.1918 )), set the star ting and ending time f or the injec tion in the Start Time and Stop Time fields .When In-C ylinder mesh motion is enabled , set the star ting and ending cr ank angles f or the injec tion in the Start Crank Angle and Stop C rank A ngle fields . •vapor pr essur e Set the v apor pr essur e go verning the flo w thr ough the in ternal or ifice ( in Table 16.4: List of G ov- erning P aramet ers f or In ternal N ozzle F low in the Theor y Guide ) in the Vapor P ressur e field . 1955Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting Initial C onditions f or the D iscrete Phase•diamet er Set the diamet er of the or ifice in the Injec tor Inner D iamet er field ( in Table 16.4: List of G overning Paramet ers f or In ternal N ozzle F low in the Theor y Guide ). •orifice length Set the length of the or ifice in the Orifice Length field ( in Table 16.4: List of G overning P aramet ers for In ternal N ozzle F low in the Theor y Guide ). •radius of cur vature Set the r adius of cur vature of the inlet c orner in the Corner R adius of C urvature field ( in Table 16.4: List of G overning P aramet ers f or In ternal N ozzle F low in the Theor y Guide ). •nozzle par amet er Set the c onstan t for the spr ay angle c orrelation in the Constan t A field ( in Equa tion 16.347 in the Theor y Guide ). •azimuthal angles For 3D sec tors, set the Azimuthal S tart Angle and Azimuthal S top A ngle . See The P lain-Or ifice Atomiz er M odel in the Theor y Guide for details ab out ho w these inputs ar e used . If you w ant to randomly distr ibut e the initial plac emen t of the par ticles , enable Stagger P ositions (default). The r egion o ver which par ticle r elease p oints will b e stagger ed is defined b y the sp ecified orifice diamet er. For mor e inf ormation on spa tial stagger ing, see Stagger ing of P articles in S pace and Time (p.1942 ). 24.3.8. Point Properties f or P ressur e-Swirl Atomiz er Injec tions For a pr essur e-swir l atomiz er injec tion, you will sp ecify some of the same pr operties as f or a plain-or ifice atomiz er. In addition t o the p osition, axis (if 3D), temp erature, mass flo w rate, dur ation of injec tion (if unst eady), injec tor inner diamet er, and azimuthal angles (if r elevant) descr ibed in Point Properties f or Plain-Or ifice Atomiz er Injec tions (p.1955 ), you will need t o sp ecify the f ollowing par amet ers under Point Properties : •spray angle Set the v alue of the spr ay angle of the injec ted str eam in the Spray Half A ngle field ( in Equa- tion 16.359 in the Theor y Guide ). •pressur e Set the absolut e pr essur e upstr eam of the injec tion in the Upstr eam P ressur e field ( in Table 16.4: List of G overning P aramet ers f or In ternal N ozzle F low in the Theor y Guide ). •sheet br eakup Set the v alue of the empir ical constan t tha t det ermines the length of the ligamen ts tha t are formed after sheet br eakup in the Sheet C onstan t field ( in Equa tion 16.366 in the Theor y Guide ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1956Modeling D iscrete Phase•ligamen t diamet er For shor t waves, set the pr oportionalit y constan t tha t linear ly relates the ligamen t diamet er, , to the w avelength tha t breaks up the sheet in the Ligamen t Constan t field (see Equa tion 16.367 —Equa- tion 16.370 in the Theor y Guide ). •disp ersion angle For a smo oth distr ibution of the dr oplets , the initial v elocities is v aried within this disp ersion angle . A sk etch of the Atomiz er D ispersion A ngle for a fla t fan a tomiz er is depic ted in Figur e 24.13: Flat Fan Viewed fr om A bove and fr om the S ide (p.1959 ). See The P ressur e-Swirl Atomiz er M odel in the Theor y Guide for details ab out ho w these inputs ar e used . 24.3.9. Point Properties f or A ir-Blast/A ir-A ssist A tomiz er Injec tions For an air-blast/air-assist a tomiz er, you will sp ecify some of the same pr operties as f or a plain-or ifice atomiz er. In addition t o the p osition, axis (if 3D), temp erature, mass flo w rate, dur ation of injec tion (if unst eady), injec tor inner diamet er, and azimuthal angles (if r elevant) descr ibed in Point Properties f or Plain-Or ifice Atomiz er Injec tions (p.1955 ), you will need t o sp ecify the f ollowing par amet ers under Point Properties : •outer diamet er Set the out er diamet er of the injec tor in the Injec tor Out er D iamet er field .This v alue is used in conjunc tion with the Injec tor Inner D iamet er to set the thick ness of the liquid sheet ( in Equa- tion 16.353 in the Theor y Guide ). •spray angle Set the initial tr ajec tory of the film as it lea ves the end of the or ifice in the Spray Half A ngle field ( in Equa tion 16.359 in the Theor y Guide ). •relative velocity Set the maximum r elative velocity tha t is pr oduced b y the sheet and air in the Rela tive Velocity field . •sheet br eakup 1957Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting Initial C onditions f or the D iscrete PhaseSet the v alue of the empir ical constan t tha t det ermines the length of the ligamen ts tha t are formed after sheet br eakup in the Sheet C onstan t field ( in Equa tion 16.366 in the Theor y Guide ). •ligamen t diamet er For shor t waves, set the pr oportionalit y constan t ( in Equa tion 16.369 in the Theor y Guide ) tha t linear ly relates the ligamen t diamet er, , to the w avelength tha t breaks up the sheet in the Ligamen t Constan t field . •disp ersion angle For a smo oth distr ibution of the dr oplets , the initial v elocities is v aried within this disp ersion angle . A sk etch of the Atomiz er D ispersion A ngle for a fla t fan a tomiz er is depic ted in Figur e 24.13: Flat Fan Viewed fr om A bove and fr om the S ide (p.1959 ). See The A ir-Blast/A ir-Assist A tomiz er M odel in the Theor y Guide for details ab out ho w these inputs ar e used . 24.3.10. Point Properties f or F lat-Fan A tomiz er Injec tions The fla t-fan a tomiz er mo del is a vailable only f or 3D mo dels . For this t ype of injec tion, you will define the f ollowing initial c onditions under Point Properties : •arc position Set the c oordina tes of the c enter p oint of the ar c from which the fan or igina tes in the X-C enter,Y- Center, and Z-Center fields (see Figur e 24.13: Flat Fan Viewed fr om A bove and fr om the S ide (p.1959 )). •virtual p osition Set the c oordina tes of the vir tual or igin of the fan in the X-Vir tual Or igin ,Y-Vir tual Or igin , and Z- Virtual Or igin fields .This p oint is the in tersec tion of the lines tha t mar k the sides of the fan (see Figur e 24.13: Flat Fan Viewed fr om A bove and fr om the S ide (p.1959 )). •normal v ector Set the dir ection tha t is nor mal t o the fan in the X-Fan N ormal Vector,Y-Fan N ormal Vector, and Z-Fan N ormal Vector fields . •temp erature Set the t emp erature of the str eams in the Temp erature field . •mass flo w rate Set the mass flo w rate for the str eams in the a tomiz er in the Flow R ate field . •duration of injec tion For unst eady par ticle tr acking (see Steady/Transien t Treatmen t of P articles (p.1918 )), set the star ting and ending time f or the injec tion in the Start Time and Stop Time fields .When In-C ylinder mesh motion is enabled , set the star ting and ending cr ank angles f or the injec tion in the Start Crank Angle and Stop C rank A ngle fields . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1958Modeling D iscrete Phase•spray half angle Set the initial half angle of the dr ops as the y lea ve the end of the or ifice in the Spray Half A ngle field . •orifice width Set the width of the or ifice (in the nor mal dir ection) in the Orifice Width field . •sheet br eakup Set the v alue of the empir ical constan t tha t det ermines the length of the ligamen ts tha t are formed after sheet br eakup in the Flat Fan S heet C onstan t field (see Equa tion 16.366 in the Theor y Guide ). •disp ersion angle For a smo oth distr ibution of the dr oplets , the initial v elocities is v aried within this disp ersion angle . A sk etch of the Atomiz er D ispersion A ngle is depic ted in Figur e 24.13: Flat Fan Viewed fr om A bove and fr om the S ide (p.1959 ). See The F lat-Fan A tomiz er M odel in the Theor y Guide for details ab out ho w these inputs ar e used . To randomly distr ibut e the initial plac emen t of the par ticles , enable Stagger P ositions (default). The orifice width is used as r adius t o define the r egion o ver which par ticle r elease p oints will b e stagger ed in spac e. For mor e inf ormation on spa tial stagger ing, see Stagger ing of P articles in S pace and Time (p.1942 ). Figur e 24.13: Flat Fan Viewed fr om A bove and fr om the S ide 1959Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting Initial C onditions f or the D iscrete Phase24.3.11. Point Properties f or E ffervescent Atomiz er Injec tions For an eff ervescent atomiz er injec tion, you will sp ecify some of the same pr operties as f or a plain-or ifice atomiz er. In addition t o the p osition, axis (if 3D), temp erature, mass flo w rate (including b oth flashing and non-flashing c omp onen ts), dur ation of injec tion (if unst eady), vapor pr essur e, injec tor inner dia- met er, and azimuthal angles (if r elevant) descr ibed in Point Properties f or P lain-Or ifice Atomiz er Injec- tions (p.1955 ), you will need t o sp ecify the f ollowing par amet ers under Point Properties : •mixture qualit y Set the mass fr action of the injec ted mix ture tha t vaporizes in the Mixture Q ualit y field ( in Equa tion 16.376 in the Theor y Guide ). •saturation t emp erature Set the sa turation t emp erature of the v olatile substanc e in the Saturation Temp . field . •droplet disp ersion Set the par amet er tha t controls the spa tial disp ersion of the dr oplet siz es in the Dispersion C onstan t field ( in Equa tion 16.376 in the Theor y Guide ). •spray angle Set the initial tr ajec tory of the film as it lea ves the end of the or ifice in the Maximum H alf A ngle field . See The E ffervescent Atomiz er M odel in the Theor y Guide for details ab out ho w these inputs ar e used . 24.3.12. Point Properties f or F ile Injec tions File injec tions c an op erate in t wo diff erent mo des, dep ending on the f ormat of the file: •A steady file c an b e used in b oth st eady and unst eady par ticle tr acking. In the f ormer c ase, for e very line entry in the file , a new par ticle par cel is gener ated f or e very injec tion time st ep in the usual w ay. By default , injec tion time st eps ar e iden tical to the global fluid-flo w time st eps; however, you c an change it in the Discr ete Phase M odel dialo g box. •An unst eady file c an only b e used in unst eady par ticle tr acking. Here, every line en try in the file c ontains a time stamp ( flow-time in the 13th column). At the appr opriate simula ted flow-time , ANSY S Fluen t will injec t a single par ticle par cel only onc e.That means tha t dur ing the en tire time in terval tha t it spans , Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1960Modeling D iscrete Phasean unst eady injec tion file pr oduces as man y par ticle par cels as the numb er of the da ta line en tries in the file. An unst eady file c an b e converted in to a st eady-sta te injec tion file as descr ibed in Data R educ tion of Samples (p.2059 ). The injec tion file mo de is det ermined b y the file header : •If the file do es not ha ve an y header , then it is tr eated as a st eady file f or back ward compa tibilit y reasons . •If the file c ontains a header of the e xpected f ormat, the inf ormation in the header will det ermine whether the file op erates in the st eady or unst eady mo de as fur ther descr ibed. Imp ortant Using an unst eady injec tion file f or st eady par ticle tr acking will r esult in an er ror. 24.3.12.1. Steady F ile F ormat The st eady file f or a file injec tion has the f ollowing f orm: (( x y z u v w diameter temperature mass-flow) name ) with all of the w ords denoting numer ic par amet ers in scien tific floa ting-p oint nota tion in SI units . All the par entheses ar e requir ed, but the name is optional. Sample files gener ated dur ing sampling of tr ajec tories f or st eady par ticle tr acking as descr ibed in Sampling of Trajec tories (p.2054 ) can also b e used as st eady injec tion files sinc e the y ha ve a similar file f ormat. The file c an ha ve an optional t wo-line header aut oma tically gener ated b y par ticle sampling f or st eady particle tr acking in the f ollowing f orm: (z=4 12) ( x y z u v w diameter t mass-flow mass frequency time name) In the first line , you c an r eplac e z=4 with an arbitr ary lab el tha t must not c ontain an y whit e-spac e char acters.You must not change the r est of the header , but y ou c an add an y numb er of whit e spac e char acters b etween its elemen ts. 24.3.12.2. Unst eady F ile F ormat The unst eady file must ha ve a t wo-line header of the f ollowing f ormat: (z=4 13) ( x y z u v w diameter t parcel-mass mass n-in-parcel time flow-time name) In the first line , you c an r eplac e z=4 with an arbitr ary lab el tha t must not c ontain an y whit e-spac e char acters.You must not change the r est of the header , but y ou c an add an y numb er of whit e spac e char acters b etween its elemen ts.The header is aut oma tically wr itten b y ANSY S Fluen t into every sampling file f or unst eady par ticle tr acking. The unst eady file f or a file injec tion has the f ollowing f orm: 1961Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting Initial C onditions f or the D iscrete Phase(( x y z u v w diameter temperature parcel-mass mass n-in-parcel time flow-time) name) Like for the st eady file f ormat, all the numb ers must b e in SI units , and all the par entheses ar e requir ed, but the name is optional. A file tha t ANSY S Fluen t wr ites fr om unst eady par ticle tr acking c an b e used as an injec tion file in the unst eady mo de. An unst eady injec tion file c an c ontain additional c olumns tha t can b e pr ocessed using a DEFINE_DPM_INJECTION_INIT UDF . For details , see DEFINE_DPM_INJECTION_INIT in the Fluent C ustomization Manual . Note In an unst eady injec tion file , all en tries must b e sor ted str ictly in asc ending or der of the simula ted flow-time (13th column). If you use unst eady par ticle sampling in ANSY S Fluen t to gener ate such a file , you must selec t the Sort Sample F iles option in the Sample Trajec tories dialo g box. 24.3.12.3. User Input for F ile Injec tions In the Point Properties tab in the Set Injec tion P roperties dialo g box, you c an sp ecify the f ollowing injec tion par amet ers: Start Time specifies the simula ted time when ANSY S Fluen t star ts to injec t par ticles fr om this injec tion. Stop Time specifies the simula ted time when ANSY S Fluen t stops t o injec t par ticles fr om this injec tion. Start Flow-time in F ile (optional) det ermines the line fr om which ANSY S Fluen t star ts reading the injec tion file . All line en tries in which flow-time (13th column) is less than the sp ecified v alue will b e sk ipped. For remaining lines , the injec tion r elease time is det ermined as: Start Time + flow-time - Start Flow-time in F ile The default v alue of 0 means tha t ANSY S Fluen t will r ead the injec tion file star ting fr om the first line en try. Rep eat Interval in F ile (optional) c an b e used t o put the unst eady injec tion in to a time-p eriodic mo de. Onc e ANSY S Fluen t has read the injec tion file f or the sp ecified time p eriod, it rewinds the file and star ts reading it again fr om the line fr om which it b egan. This c ycling pr ocess c ontinues un til Stop Time is reached . In this w ay, de- tailed da ta for a small time in terval can b e used t o appr oxima te a st eady sta te over longer time p eriods in an unst eady simula tion with unst eady par ticle tr acking.The default v alue of 0 means no r epetition in time . Note For st eady injec tion files ,Start Flow-time in F ile and Rep eat In terval in F ile are ignor ed. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1962Modeling D iscrete Phase24.3.13. Point Properties f or C ondensa te Injec tions For a c ondensa te injec tion, you will define only the dur ation of the injec tion b y setting the star ting and ending time f or the injec tion in the Start Time and Stop Time fields under the Point Properties tab in the Set Injec tion P roperties dialo g box.The dur ation of the injec tion det ermines the time during which film c ondensa tion will b e initia ted on the w alls tha t ha ve the Film C ondensa tion option enabled . 24.3.14. Using the Rosin-R ammler D iamet er D istribution M etho d For liquid spr ays, a convenien t represen tation of the dr oplet siz e distr ibution is the R osin-R ammler expression. The c omplet e range of siz es is divided in to an adequa te numb er of discr ete in tervals; each represen ted b y a mean diamet er for which tr ajec tory calcula tions ar e performed . If the siz e distr ibution is of the R osin-R ammler t ype, the mass fr action of dr oplets of diamet er gr eater than is giv en b y (24.8) wher e is the siz e constan t and is the siz e distr ibution par amet er. By default , you will define the siz e distr ibution of par ticles b y inputting a diamet er for the first and last p oints and using the linear equa tion ( Equa tion 24.7 (p.1949 )) to vary the diamet er of each par ticle stream in the gr oup .When y ou w ant a diff erent mass flo w rate for each par ticle/dr oplet siz e, however, the linear v ariation ma y not yield the distr ibution y ou need .Your par ticle siz e distr ibution ma y be defined most easily b y fitting the siz e distr ibution da ta to the R osin-R ammler equa tion. In this appr oach, the c omplet e range of par ticle siz es is divided in to a set of discr ete siz e ranges , each t o be defined b y a single str eam tha t is par t of the gr oup . Assume , for e xample , tha t the par ticle siz e da ta ob eys the following distr ibution: Mass F raction in R ange Diamet er R ange ( m) 0.05 0–70 0.10 70–100 0.35 100–120 0.30 120–150 0.15 150–180 0.05 180–200 The R osin-R ammler distr ibution func tion is based on the assumption tha t an e xponen tial r elationship exists b etween the dr oplet diamet er, , and the mass fr action of dr oplets with diamet er gr eater than , : (24.9) ANSY S Fluen t refers t o the quan tity in Equa tion 24.9 (p.1963 ) as the Mean D iamet er and t o as the Spread P aramet er.These par amet ers ar e sp ecified b y you (in the Set Injec tion P roperties D ialog Box (p.3917 ) under the First P oint heading) t o define the R osin-R ammler siz e distr ibution. To solv e for these par amet ers, you must fit y our par ticle siz e da ta to the R osin-R ammler e xponen tial equa tion. To determine these inputs , first r ecast the giv en dr oplet siz e da ta in t erms of the R osin-R ammler f ormat. For the e xample da ta pr ovided ab ove, this yields the f ollowing pairs of and : 1963Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting Initial C onditions f or the D iscrete PhaseMass F raction with D iamet er Greater than , Diamet er, ( m) 0.95 70 0.85 100 0.50 120 0.20 150 0.05 180 (0.00) 200 A plot of vs. is sho wn in Figur e 24.14: Example of C umula tive Size Distribution of P articles (p.1964 ). Figur e 24.14: Example of C umula tive Size D istribution of P articles Next, der ive values of and such tha t the da ta in Figur e 24.14: Example of C umula tive Size Distribution of P articles (p.1964 ) fit Equa tion 24.9 (p.1963 ).The v alue f or is obtained b y noting tha t this is the v alue of at which . From Figur e 24.14: Example of C umula tive Size Distribution of Particles (p.1964 ), you c an estima te tha t this o ccurs f or m.The numer ical value f or is giv en by (24.10) By substituting the giv en da ta pairs f or and into this equa tion, you c an obtain v alues f or and find an a verage. Doing so yields an a verage v alue of = 4.52 f or the e xample da ta ab ove.The resulting R osin-R ammler cur ve fit is c ompar ed t o the e xample da ta in Figur e 24.15: Rosin-R ammler Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1964Modeling D iscrete PhaseCurve Fit for the Example P article S ize Data (p.1965 ).You c an en ter v alues f or and , as w ell as the diamet er range of the da ta and the t otal mass flo w rate for the c ombined individual siz e ranges , using the Set Injec tion P roperties D ialog Box (p.3917 ). This t echnique of fitting the R osin-R ammler cur ve to spr ay da ta is used when r eporting the R osin- Rammler diamet er and spr ead par amet er in the Discr ete Phase S ummar y dialo g box in Summar y Reporting of C urrent Particles (p.2061 ). Figur e 24.15: Rosin-R ammler C urve Fit for the E xample P article S ize D ata A sec ond R osin-R ammler distr ibution is also a vailable based on the na tural lo garithm of the par ticle diamet er. If in y our c ase, the smaller-diamet er par ticles in a R osin-R ammler distr ibution ha ve higher mass flo ws in c ompar ison with the lar ger-diamet er par ticles , you ma y want better resolution of the smaller-diamet er par ticle str eams , or “bins ”.You c an ther efore cho ose t o ha ve the diamet er incr emen ts in the R osin-R ammler distr ibution done unif ormly b y . In the standar d Rosin-R ammler distr ibution, a par ticle injec tion ma y ha ve a diamet er range of 1 t o 200 m. In the lo garithmic R osin-R ammler distr ibution, the same diamet er range w ould b e converted t o a range of to , or ab out 0 t o 5.3. In this w ay, the mass flo w in one bin w ould b e less-hea vily skewed as c ompar ed t o the other bins . When a R osin-R ammler siz e distr ibution is b eing defined f or the gr oup of str eams , you should define (in addition t o the initial v elocity, position, and t emp erature) the f ollowing par amet ers, which app ear under the heading f or the First P oint: •Total F low R ate 1965Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting Initial C onditions f or the D iscrete PhaseThis is the t otal mass flo w rate of the streams in the gr oup . Note tha t in axisymmetr ic pr oblems this mass flo w rate is defined p er radians and in 2D pr oblems p er unit met er depth. •Min. Diamet er This is the smallest diamet er to be consider ed in the siz e distr ibution. •Max. Diamet er This is the lar gest diamet er to be consider ed in the siz e distr ibution. •Mean D iamet er This is the siz e par amet er, , in the R osin-R ammler equa tion ( Equa tion 24.9 (p.1963 )). •Spread P aramet er This is the e xponen tial par amet er, , in Equa tion 24.9 (p.1963 ). 24.3.14.1. The St ochastic R osin-R ammler D iamet er D istribution Metho d For a tomiz er injec tions , a R osin-R ammler distr ibution is assumed f or the par ticles e xiting the injec tor. In or der t o decr ease the numb er of par ticles nec essar y to accur ately descr ibe the distr ibution, the diamet er distr ibution func tion is r andomly sampled f or each instanc e wher e new par ticles ar e in tro- duced in to the domain. The R osin-R ammler distr ibution c an b e wr itten as (24.11) wher e is the mass fr action smaller than a giv en diamet er , is the R osin-R ammler diamet er and is the R osin-R ammler e xponen t.This e xpression c an b e inverted b y tak ing lo gs of b oth sides and rearranging , (24.12) Given a mass fr action along with par amet ers and , this func tion will e xplicitly pr ovide a diamet er, . Diamet ers f or the a tomiz er injec tors descr ibed in Point Properties f or P lain-Or ifice Atomiz er Injec- tions (p.1955 ) are obtained b y unif ormly sampling in Equa tion 24.12 (p.1966 ). 24.3.15. Creating and M odifying Injec tions You will use the Injec tions branch in the Outline View and the Injec tions D ialog Box (p.3837 ) (Fig- ure 24.17: The Injec tions D ialog Box (p.1967 ),Figur e 24.16: The Injec tions B ranch in the Outline View (p.1967 )) to cr eate, copy, delet e, list, read, and wr ite injec tions . Setup → Models → Discr ete Phase → Injec tions New... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1966Modeling D iscrete PhaseFigur e 24.16: The Injec tions Br anch in the Outline View Figur e 24.17: The Injec tions D ialo g Box (You c an also click the Injec tions ... butt on in the Discrete Phase M odel D ialog Box (p.3360 ) to op en the Injec tions dialo g box.) Note [Linux Only] I f you ar e not par t of a video gr oup , a session on a lo cal Linux machine with SLES11, SP4, and Op enGL ma y termina te abnor mally dur ing an injec tion setup f or the discr ete phase mo del c ase.To avoid this issue , you should r estar t the ANSY S Fluen t session with the dr iver option -x11 or y ou should ensur e tha t you ar e added t o the video gr oup on that machine .Workaround: Deactivate the injec tion visualiza tion dur ing the c ase setup b y using the f ollowing scheme c ommand: rpsetvar 'dpm/visualize-injections? #f) 1967Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting Initial C onditions f or the D iscrete Phase24.3.15.1. Creating Injec tions To cr eate an injec tion, click the Create butt on.The Set Injec tion P roperties D ialog Box (p.3917 ) will open aut oma tically t o allo w you t o set the injec tion pr operties (as descr ibed in Defining Injec tion Properties (p.1969 )). After the injec tion is cr eated, the new injec tion will app ear in the Injec tions list, in the Injec tions dialo g box. 24.3.15.2. Mo difying Injec tions To mo dify an e xisting injec tion, selec t its name in the Injec tions list and click the Set... butt on.The Set Injec tion P roperties dialo g box will op en, and y ou c an mo dify the pr operties as needed . If you ha ve two or mor e injec tions f or which y ou w ant to set some of the same pr operties, selec t their names in the Injec tions list and click the Set... butt on.The Set M ultiple Injec tion P roperties dialo g box will op en, which will allo w you t o set the c ommon pr operties. For instr uctions ab out using this dialo g box, see Defining P roperties C ommon t o M ore than One Injec tion (p.1981 ). 24.3.15.3. Copying Injec tions To copy an e xisting injec tion t o a new injec tion, selec t the e xisting injec tion in the Injec tions list and click the Copy butt on.The Set Injec tion P roperties D ialog Box (p.3917 ) will op en with a new injec tion that has the same pr operties as the injec tion y ou selec ted.This is useful if y ou w ant to set another injec tion with similar pr operties. 24.3.15.4. Deleting Injec tions You c an delet e an injec tion b y selec ting its name in the Injec tions list and click ing the Delet e butt on. 24.3.15.5. Listing Injec tions To list the initial c onditions f or the par ticle str eams in the selec ted injec tion, click the List butt on. ANSY S Fluen t reports the initial c onditions (in SI units) in the c onsole under v arious c olumns: •The par ticle str eam numb er is in the c olumn headed NO. •The par ticle t ype (IN for iner t,DR for dr oplet , or CP for combusting par ticle) is in the c olumn headed TYP . •The , , and positions ar e in the c olumns headed (X) ,(Y) , and (Z) . •The , , and velocities ar e in the c olumns headed (U) ,(V) , and (W) . •The t emp erature is in the c olumn headed (T) . •The diamet er is in the c olumn headed (DIAM) . •The mass flo w rate in the c olumn headed (MFLOW) . 24.3.15.6. Reading and Writing Injec tions To transf er inf ormation ab out DPM injec tions fr om one c ase file t o another , use the Read ... and Write... butt ons.You c an wr ite selec ted injec tions t o a file , which c an b e read in to a diff erent ANSY S Fluen t session, simplifying the setup of new c ase files .To wr ite the injec tion, selec t the injec tion fr om Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1968Modeling D iscrete Phasethe list , then click Write....The S elec t File D ialog Box (p.569) will op en wher e you c an en ter the name of y our injec tion file .To read in an injec tion, click Read ... to op en The S elec t File D ialog Box (p.569) wher e you will selec t the injec tion file t o read in. If the injec tion tha t you imp orted has the same name as tha t in y our cur rent case, then ANSY S Fluen t will r ename the imp orted injec tion. After reading injec tions , you ma y need t o visit the Injec tions dialo g box to mo dify the settings f or the injec tion ma terial and the DPM la ws sinc e the pr esumed settings ma y ha ve changed in the cur rent case file setup . 24.3.16. Defining Injec tion P roperties Onc e you ha ve created an injec tion (using the Injec tions D ialog Box (p.3837 ), as descr ibed in Creating and M odifying Injec tions (p.1966 )), you will use the Set Injec tion P roperties D ialog Box (p.3917 ) (Fig- ure 24.18: The S et Injec tion P roperties D ialog Box (p.1969 )) to define the injec tion pr operties. (Rememb er that this dialo g box will op en when y ou cr eate a new injec tion, or when y ou selec t an e xisting injec tion and click the Set... butt on in the Injec tions dialo g box.) Figur e 24.18: The S et Injec tion P roperties D ialo g Box The pr ocedur e for defining an injec tion is as f ollows: 1969Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting Initial C onditions f or the D iscrete Phase1.If you w ant to change the default name of the injec tion, enter a new name in the Injec tion N ame field . This is r ecommended if y ou ar e defining a lar ge numb er of injec tions so y ou c an easily distinguish them. When assigning names t o your injec tions , keep in mind the selec tion shor tcut descr ibed in Creating and Modifying Injec tions (p.1966 ). 2.Choose the t ype of injec tion in the Injec tion Type drop-do wn list. The injec tion choic es (single ,group , cone ,surface,plain-or ifice-atomiz er,pressur e-swir l-atomiz er,air-blast-a tomiz er,flat-fan-a tomiz er, effervescent-atomiz er,condensa te, and file) are descr ibed in Injec tion Types (p.1944 ). Note tha t if y ou selec t an y of the a tomiz er mo dels , you also must set the Visc osit y and Droplet S urface Tension in the Create/Edit M aterials dialo g box. Imp ortant Note tha t only sur face injec tions fr om b oundar y sur faces will b e mo ved with the mesh when a sliding mesh or a mo ving or def orming mesh is b eing used . 3.If you ar e defining a single or condensa te injec tion, go t o the ne xt step. For a group ,cone , or an y of the atomiz er injec tions , set the Numb er of S treams in the gr oup , spray cone , or a tomiz er. If you ar e defining a surface injec tion (see Figur e 24.19: Setting Sur face Injec tion P roperties (p.1971 )), choose the sur face(s) fr om which the par ticles will b e released in the Release F rom S urfaces list. If you ar e reading the injec tion fr om a file , click the File... butt on a t the b ottom of the Set Injec tion Properties D ialog Box (p.3917 ) and sp ecify the file t o be read in the r esulting Selec t File dialo g box. The par amet ers in the injec tion file must b e in SI units . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1970Modeling D iscrete PhaseFigur e 24.19: Setting S urface Injec tion P roperties 4.Selec t Massless ,Iner t,Droplet ,Combusting , or Multic omp onen t as the Particle Type.The a vailable types ar e descr ibed in Particle Types (p.1947 ). Note tha t for the condensa te injec tion, the only a vailable particle t ypes ar e Droplet and Multic omp onen t. 5.Choose the ma terial for the par ticle(s) in the Material drop-do wn list. If this is the first time y ou ha ve created a par ticle of this t ype, you c an cho ose fr om all of the ma- terials of this t ype defined in the da tabase . If you ha ve alr eady created a par ticle of this t ype, the only a vailable ma terial will b e the ma terial y ou selec ted f or tha t par ticle .You c an define additional materials b y copying them fr om the da tabase or cr eating them fr om scr atch, as discussed in Setting Discrete-Phase P hysical Properties (p.2011 ) and descr ibed in detail in Using the Create/Edit M aterials Dialog Box (p.1081 ). Imp ortant Note tha t you will not cho ose a Material for a Massless par ticle t ype. 1971Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting Initial C onditions f or the D iscrete Phase6.If you ar e defining a group ,cone , or surface injec tion and y ou w ant to change fr om the default linear (for gr oup injec tions) or unif orm (for cone and sur face injec tions) in terpolation metho d used t o det ermine the siz e of the par ticles , selec t rosin-r ammler or rosin-r ammler-lo garithmic in the Diamet er D istribution drop-do wn list. The R osin-R ammler metho d for det ermining the r ange of diamet ers f or a gr oup injec tion is descr ibed in Using the R osin-R ammler D iamet er D istribution M etho d (p.1963 ). 7.If you ha ve created a cust omiz ed par ticle la w using user-defined func tions , enable the Custom option under Laws and sp ecify the appr opriate laws as descr ibed in Custom P article La ws (p.1980 ). 8.If your par ticle t ype is Iner t, go t o the ne xt step. If you ar e defining Droplet par ticles , selec t the gas phase species cr eated b y the v aporization and b oiling la ws (La ws 2 and 3) in the Evaporating S pecies drop- down list. If you ar e defining Combusting par ticles , selec t the gas phase sp ecies cr eated b y the de volatiliza tion law (La w 4) in the Devolatilizing S pecies drop-do wn list , the gas phase sp ecies tha t par ticipa tes in the sur face char c ombustion r eaction (La w 5) in the Oxidizing S pecies list, and the gas phase species cr eated b y the sur face char c ombustion r eaction (La w 5) in the Produc t Species list. Note that if the Combustion M odel for the selec ted c ombusting par ticle ma terial (in the Create/Edit Materials dialo g box) is the multiple-sur face-reac tion mo del, then the Oxidizing S pecies and Produc t Species lists will b e disabled b ecause the r eaction st oichiometr y has b een defined in the mixture ma terial. If you ar e defining Multic omp onen t par ticles , ma w 7 will go in to eff ect. Notice tha t the Comp onen ts tab will b ecome ac tive when this par ticle t ype is selec ted. See b elow for inf ormation on the Com- ponen ts tab . 9.Click the Point Properties tab (the default), and sp ecify the p oint properties (p osition, velocity, diamet er, temp erature, and—if appr opriate—mass flo w rate and an y atomiz er-related par amet ers) as descr ibed f or each injec tion t ype in Point Properties f or S ingle Injec tions (p.1948 ) – Point Properties f or E ffervescent At- omiz er Injec tions (p.1960 ). For sur face injec tions , you c an enable the Scale F low R ate by Face Area and y ou c an cho ose the injec tion dir ection. To use the fac e nor mal dir ection f or the injec tion dir ection, selec t the Injec t Using F ace Normal D irection option under Point Properties (Figur e 24.19: Setting Sur face Injec tion Properties (p.1971 )). Onc e this option is selec ted, you only need t o sp ecify the v elocity magnitude of the injec tion, not the individual c omp onen ts of the v elocity magnitude . 10.If you w ant to set up injec tion-sp ecific ph ysics mo dels such as dr ag la ws, Brownian motion, and br eakup, click the Physical M odels tab and c onfigur e the injec tion ph ysics mo dels as descr ibed in Specifying Injec- tion-S pecific P hysical M odels (p.1973 ). 11.If the flo w is turbulen t and y ou w ant to include the eff ects of turbulenc e on the par ticle disp ersion, click the Turbulen t Dispersion tab , enable the Discr ete Random Walk M odel under Stochastic tr ack ing or the Cloud M odel, and set the r elated par amet ers as descr ibed in Specifying Turbulen t Dispersion of Particles (p.1978 ). 12.If you ha ve enabled Unstead y Particle Track ing, you c an define settings f or ho w the par cels ar e released . Click the Parcel tab and selec t a Parcel Release M etho d from the dr op-do wn list. The default metho d is standar d, in which a single par cel is r eleased p er injec tion str eam p er time st ep. Alternatively c an cho ose constan t-numb er,constan t-mass , or constan t-diamet er. Refer to Steady/Transien t Treatmen t of P articles (p.1918 ) for details of these metho ds. 13.If your c ombusting par ticle includes an e vaporating ma terial, click the Wet C ombustion tab , selec t the Wet C ombustion M odel option, and then selec t the ma terial tha t is e vaporating/b oiling fr om the par ticle Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1972Modeling D iscrete Phasebefore de volatiliza tion b egins in the Liquid M aterial drop-do wn list. You should also set the v olume fraction of the liquid pr esen t in the par ticle b y en tering the v alue of the Liquid F raction . Finally , selec t the gas phase sp ecies cr eated b y the e vaporating and b oiling la ws in the Evaporating S pecies drop- down list in the t op par t of the dialo g box. 14.If you include multic omp onen t droplets as the ma terial in y our discr ete phase mo del, the Comp onen ts tab will b ecome ac tive. In this tab , you will sp ecify the Mass F raction of each of the c omp onen ts. Note that the sum of the mass fr actions should add up t o unit y, other wise ANSY S Fluen t will adjust the v alues such tha t you ha ve a sum of 1 f or the mass fr action, and will pr ompt y ou t o acc ept the en try. Under Evaporating S pecies , selec t not-v aporizing if the c omp onen t in the par ticle do es not v aporize. Other wise , selec t the sp ecies tha t will b e vaporized. To change the c omp onen ts of the multic omp onen t droplet: a.In the Create/Edit M aterials dialo g box, either define a new dr oplet ma terials or c opy appr opriate materials fr om the F luen t ma terials da tabase . b.Click Edit... next to Mixture Species . c.In the Species dialo g box, add the dr oplet ma terials tha t you ha ve copied or defined t o the Selec ted Species list and r emo ve unw anted ma terials. 15.If you w ant to use a user-defined func tion t o initializ e the injec tion pr operties, click the UDF tab t o acc ess the UDF inputs .You c an selec t an Initializa tion func tion under User-D efined F unc tions to mo dify injec tion properties a t the time the par ticles ar e injec ted in to the domain. This allo ws the p osition and/or pr operties of the injec tion t o be set as a func tion of flo w conditions . More inf ormation ab out user-defined func tions can b e found in the Fluen t Customiza tion M anual . 16.If you ha ve defined mor e than one par ticle sur face sp ecies , for e xample , carbon ( C ) and sulfur ( S ), you will need t o sp ecify the mass fr action of each par ticle sur face sp ecies in the c ombusting par ticle .To do so , click the Multiple Reac tions tab , and en ter the Species M ass F ractions .These mass fr actions r efer to the c ombustible fr action of the c ombusting par ticle , and should sum t o 1. If ther e is only one sur face species in the mix ture ma terial, the mass fr action of tha t species will b e set t o 1, and y ou will not sp ecify anything under Multiple S urface Reac tions . 24.3.17. Specifying Injec tion-S pecific P hysical M odels Drag and br eakup mo dels c an b e sp ecified on a p er-injec tion basis , allo wing y ou t o sp ecify the most appr opriate mo dels f or each injec tion in y our mo del. These p er-injec tion mo dels ar e sp ecified on the Physical M odels tab of the Set Injec tion P roperties dialo g box. 24.3.17.1. Drag L aws The spher ical,nonspher ical,Stokes-C unningham , and high-M ach-numb er laws descr ibed in Particle Force Balanc e in the Theor y Guide are alw ays available , and the dynamic-dr ag law descr ibed in Dy- namic D rag M odel Theor y in the Theor y Guide is a vailable only when one of the dr oplet br eakup models is used in c onjunc tion with unst eady tracking. See Breakup (p.1975 ) for inf ormation ab out en- abling the dr oplet br eakup mo dels .The Grace and Ishii-Z uber drag la ws descr ibed in Bubbly F low Drag La ws in the Fluent Theor y Guide allo w to mo del the dr ag c oefficien t in gas-liquid flo ws in which the bubbles c an ha ve a r ange of diff erent shap es. Both dr ag la ws are only a vailable if the magnitude and dir ection of the gr avity vector ar e sp ecified in the Operating C onditions dialo g box.The r emaining three,Wen-Y u,Gidasp ow, and Syamlal-OBr ien are available only when the dense discr ete phase model is enabled ( Including the D ense D iscrete Phase M odel (p.2236 )) and the flo w regime c onsists 1973Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting Initial C onditions f or the D iscrete Phaseof a dense gas-solid . However, with these mo dels , you c annot v erify whether it r eally is a dense flo w or a gas-solid flo w. It is up t o you t o decide . In an y case, these dr ag f ormula tions ar e suitable f or dense gas-solid flo ws. If the spher ical,high-M ach-numb er,dynamic-dr ag,Wen-Y u,Gidasp ow, or Syamlal-OBr ien drag law is selec ted, no fur ther inputs ar e requir ed. If the nonspher ical law is selec ted, the par ticle Shap e Factor ( in Equa tion 16.75 in the Theor y Guide ) must b e sp ecified .The shap e fac tor v alue c annot exceed 1. For the Stokes-C unningham law, the Cunningham C orrection factor ( in Equa tion 16.78 in the Theor y Guide ) must b e sp ecified . 24.3.17.2. Particle R otation To set-up par ticle r otation, follow the st eps b elow: 1.In the Set Injec tion P roperties dialo g box, under the Physical M odels tab , enable Particle Rota tion . The options r elated t o the par ticle r otation f eature app ear in the Set Injec tion P roperties dialo g box. 2.From the Rota tional D rag L aw drop-do wn list , selec t the mo del f or calcula ting the r otational dr ag coefficien t .The following options ar e available: Dennis-et-al Uses Equa tion 16.90 in the Fluent Theor y Guide to calcula te the r otational dr ag c oefficien t . none (default) Implies z ero torque , tha t is, it excludes the influenc e of the fluid on the r otational par ticle motion. 3.From the Magnus Lif t Law drop-do wn list , selec t the mo del f or calcula ting the r otational lif t coefficien t .The following mo dels ar e available: Oesterle-Bui-D inh Uses O esterle and B ui D inh’s formula tion ( Equa tion 16.18 in the Fluent Theor y Guide ). Tsuji-et-al Is based on the par ticle spin r ate (Equa tion 16.19 in the Fluent Theor y Guide ). Rubino w-K eller Uses a linear dep endenc e of the r otational lif t coefficien t on the spin r ate (Equa tion 16.21 in the Fluent Theor y Guide ). none (default) Implies tha t the M agnus lif t will not b e included in y our simula tion. 4.Under the Point Properties tab , specify angular v elocity comp onen ts for single ,group , and surface injec tions; and angular v elocity magnitudes f or cone injec tions . 5.For each w all with a reflec t boundar y condition f or the discr ete phase , specify the fr iction c oefficien t ( in Equa tion 16.216 and Equa tion 16.221 in the Fluent Theor y Guide ) under the DPM tab of the Wall dialo g box. For details , see Friction C oefficien t (p.1991 ). The par ticle r otation mo del options ar e also acc essible thr ough the t ext user in terface, under define/models/dpm/injections/injection-properties/set/physical-mod- els/particle-rotation . Note tha t the physical-models command b ecomes a vailable only Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1974Modeling D iscrete Phaseafter y ou ha ve selec ted the injec tion(s) using the pr ompts of the define/models/dpm/injec- tions/properties/set/pick-injections-to-set text command . 24.3.17.3. Rough Wall Mo del To use the r ough w all mo del f or w alls with the reflec t boundar y condition t ype: 1. In the Injec tion S ettings dialo g box, under the Physical M odels tab , selec t Rough Wall M odel. 2. In the Wall boundar y conditions dialo g box for the appr opriate wall, under the DPM tab , selec t reflec t from the Boundar y Cond .Type drop-do wn list. 3. Specify the f ollowing w all roughness par amet ers: Ra is the w all mean r oughness ( in Equa tion 16.223 in the Fluent Theor y Guide ) Rq is the standar d de viation of the r oughness str ucture ( in Equa tion 16.223 in the Fluent Theor y Guide ) RSm is the mean r oughness slop e (the a verage distanc e between p eaks of w all ma terial) ( in Equa- tion 16.223 in the Fluent Theor y Guide ) Note Note tha t the DPM Wall Roughness P aramet ers will only app ear in the Wall dialo g box with the reflect DPM b oundar y condition t ype if the Rough Wall M odel is selec ted in the Injec tion S ettings dialo g box. For inf ormation ab out the r ough w all mo del, see Rough Wall M odel in the Fluent Theor y Guide . 24.3.17.4. Brownian Motion E ffec ts For sub-micr on par ticles in laminar flo w, you ma y want to include the eff ects of B rownian motion (descr ibed in Brownian F orce in the Theor y Guide ) on the par ticle tr ajec tories.To do so , enable the Brownian M otion option under the Physical M odels tab . In or der t o include B rownian motion eff ects, you must also selec t the Stokes-C unningham drag la w in the Drag L aw drop-do wn list under Drag Paramet ers, and sp ecify the Cunningham C orrection ( in Equa tion 16.78 in the Theor y Guide ). This option is a vailable only when the Energy equa tion is enabled (in the Models group). 24.3.17.5. Break up To enable the mo deling of par ticle br eakup f or the injec tion, selec t Enable Br eak up and cho ose the Break up M odel (TAB,Wave,KHR T,SSD or Madabhushi ) from the dr op-do wn list. A detailed descr ip- tion of these mo dels c an b e found in Secondar y Breakup M odel Theor y in the Theor y Guide . •For the TAB mo del, you must sp ecify the f ollowing v alues: 1975Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting Initial C onditions f or the D iscrete Phasey0: Is the initial dist ortion a t time equal t o zero ( in Equa tion 16.383 in the Theor y Guide ).The default value ( ) is r ecommended .– –The numb er of Break up P arcels:To split the dr oplet in to se veral child par cels, as descr ibed in Velocity of C hild D roplets in the Theor y Guide .The diamet er of the child par cels is sampled fr om a R osin-R ammler distr ibution. This c an b e swit ched off in the TUI with the c ommand: /define/models/dpm/spray-model/tab-randomize-breakup-parcel-diameter? •For the Wave mo del, you must sp ecify the f ollowing v alues: –B0: Is the c onstan t in Equa tion 16.413 in the Theor y Guide . –B1: Is the c onstan t in Equa tion 16.415 in the Theor y Guide . Note You will gener ally not need t o mo dify the v alue of B0, as the default v alue 0.61 is acc ept- able f or near ly all c ases . A v alue of 1.73 is r ecommended f or B1. The Wave mo del implemen tation has b een f ormula ted t o deal with the initial br eakup of a c ylindr ical liquid jet. In the R ayleigh r egime (tha t is, at low gas Weber numb ers), a cylindr ical jet br eaks up into dr oplets whose diamet ers ar e lar ger than tha t of the jet itself . In this r egime , the mo del assumes that the diamet er of the c ontinuous , cylindr ical liquid jet has b een en tered as initial diamet er in the injec tion. Therefore, the dr oplet diamet er can gr ow b eyond the initial diamet er. For details , see Droplet B reakup in the Fluent Theor y Guide . If you w ant to suppr ess this f eature of the Wave mo del, use the TUI c ommand: /define/models/dpm/spray-model/wave-allow-rayleigh-growth? no Note tha t this tak es eff ect unc onditionally f or all injec tions using the Wave or KHR T breakup models . •For the KHR T mo del, you must sp ecify the f ollowing v alues: –B0: Is the c onstan t in Equa tion 16.413 in the Theor y Guide . –B1: Is the c onstan t in Equa tion 16.415 in the Theor y Guide . –Ctau : Is the c onstan t in Equa tion 16.420 in the Theor y Guide . –CRT: Is the c onstan t in Equa tion 16.421 in the Theor y Guide . –CL: :s the c onstan t in Equa tion 16.416 in the Theor y Guide . The c onstan ts B0 and B1 are the same as f or the Wave mo del. As for the Wave mo del descr ibed ab ove, the KHR T mo del is f ormula ted t o deal with the initial breakup of a c ylindr ical liquid jet. The b ehavior in the R ayleigh r egime is as descr ibed ab ove for the Wave mo del and the same TUI c ommand c an b e used t o mo dify the b ehavior. In addition, the KHR T mo del uses the Liquid C ore Approxima tion as descr ibed in Liquid C ore Length in the Fluent Theor y Guide .To suppr ess the use of the Liquid C ore Approxima tion y ou c an set the L evich c onstan t, , to zero. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1976Modeling D iscrete Phase•For the SSD mo del, you must sp ecify the f ollowing v alues: –Critical We: Is the cr itical Weber numb er in Equa tion 16.422 in the Theor y Guide . –Core B1 : Is B in Equa tion 16.423 in the Theor y Guide . –Target Np : Is the numb er of dr oplets giv en t o each child par cel, before sc aling is used t o giv e the c orrect overall mass . –Xi: Is in Equa tion 16.424 in the Theor y Guide . Note Xi is a nega tive value: exp(X i) is a t ypic al fac tor b y which daugh ter par ticles ar e smaller than the or iginal par cel. •To set up the Madabhushi breakup mo del, follow the st eps b elow: Note –For the M adabhushi br eakup mo del, the most appr opriate injec tion t ypes ar e single , group , and c one (solid-c one). The r ecommended t ype is a solid c one injec tion. –The M adabhushi br eakup mo del is a vailable only with the dynamic-dr ag law, which is automa tically selec ted fr om the Drag L aw drop-do wn list when the M adabhushi br eakup model is chosen. 1.In the Set Injec tion P roperties dialo g box, define the Point Properties for the selec ted injec tion t ype (single , group , or solid c one) as f ollows: a.Specify X-,Y-, and Z- P osition in such a w ay tha t the injec ted dr oplets build a c olumn o ver the midp oint of the no zzle or ifice exit. b.Set Diamet er to the jet diamet er (no zzle or ifice exit diamet er). c.(single and gr oup injec tions only) S et X-,Y-, and Z- Velocity to the inlet v elocity comp onen ts in x, y, and z dir ections , respectively. d.(solid c one injec tions only) S et Velocity M agnitude and X-,Y-, and Z- A xis to the inlet v elocity magnitude and the dir ection of the jet , respectively. e.Set Flow R ate (single and gr oup injec tions) or Total F low R ate (solid c one injec tions) t o the no zzle orifice flo w rate. f.(solid c one injec tions only) S et Cone angle to 0 and Out er R adius to the jet r adius in or der t o specify a p erpendicular jet inflo w. g.(solid c one injec tions only) In the Cone Injec tor P aramet ers group b ox, selec t Uniform M ass Distribution . 2.In the Physical M odels tab , specify the f ollowing M adabhushi mo del par amet ers: 1977Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting Initial C onditions f or the D iscrete Phase–For pr imar y br eakup based on the Wave br eakup mo del, specify : →B0 and B1: Are the same c onstan ts as f or the Wave mo del. The r ecommended v alues f or the Madabhushi mo del ar e B0= 2.44 and B1=10. See Wave Breakup M odel for details ab out these paramet ers. →Jet D iamet er: Is the no zzle or ifice exit diamet er. –For pr imar y br eakup r elated t o the c olumn br eakup mechanism, specify : →Ligamen t Factor: Adjusts the diamet er of the child dr oplets ar ising fr om the c olumn br eakup mechanism. →C0: Is the c olumn br eakup time c onstan t tha t controls ho w fast the c olumn br eakup o ccurs .The value r ecommended f or the M adabhushi br eakup mo del is C0=3.44. 3.From the Drag L aw drop-do wn list , selec t dynamic-dr ag. The dr ag is d ynamic ally adapt ed in the M adabhushi br eakup mo del. For mor e inf ormation ab out the M adabhushi br eakup mo del, see Madabhushi B reakup M odel in the Fluent Theor y Guide . For st eady-sta te simula tions , you also must sp ecify an appr opriate Particle Time S tep S ize and the Numb er of Time S teps, which will c ontrol the spr ay densit y. See Options f or In teraction with the Continuous P hase (p.1918 ) for mor e inf ormation. Note tha t you ma y want to use the d ynamic dr ag la w when y ou use one of the br eakup mo dels . See Drag La ws (p.1925 ) for inf ormation ab out cho osing the dr ag la w. 24.3.18. Specifying Turbulen t Dispersion of P articles As men tioned in Defining Injec tion P roperties (p.1969 ), you c an cho ose f or each injec tion st ochastic tracking or cloud tr acking as the metho d for mo deling turbulen t disp ersion of par ticles . 24.3.18.1. Stochastic Track ing For turbulen t flo ws, if y ou cho ose t o use the st ochastic tr acking t echnique , you must enable the Discr ete Random Walk M odel and sp ecify the Numb er of Tries. Stochastic tr acking includes the effect of turbulen t velocity fluc tuations on the par ticle tr ajec tories using the DR W mo del descr ibed in Stochastic Tracking in the Theor y Guide . 1.Click the Turbulen t Dispersion tab in the Set Injec tion P roperties dialo g box. 2.Enable st ochastic tr acking b y tur ning on the Discr ete Random Walk M odel under Stochastic Track ing. 3.Specify the Numb er of Tries: Selec ting the Turbulen t Dispersion mo del t ells ANSY S Fluen t to include turbulen t velocity fluc- tuations in the par ticle f orce balanc e as in Equa tion 16.22 in the Theor y Guide .The tr ajec tory is comput ed mor e than onc e if y our input e xceeds 1: two trajec tory calcula tions ar e performed if you en ter 2, three tr ajec tory calcula tions ar e performed if y ou en ter 3, and so on. Each tr ajec tory calcula tion includes a new st ochastic r epresen tation of the turbulen t contributions t o the tr ajec tory equa tion. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1978Modeling D iscrete PhaseWhen a sufficien t numb er of tr ies is r equest ed, the tr ajec tories c omput ed will include a sta tistic al represen tation of the spr ead of the par ticle str eam due t o turbulenc e. Note tha t for unst eady particle tr acking, the Numb er of Tries is set t o 1 if using st ochastic tr acking. If you w ant the char acteristic lif etime of the edd y to be random ( Equa tion 16.33 in the Theor y Guide ), enable the Random E ddy Lif etime option. You will gener ally not need t o change the Time Sc ale Constan t ( in Equa tion 16.24 in the Theor y Guide ) from its default v alue of 0.15, unless y ou ar e using the R eynolds S tress turbulenc e mo del (RSM), in which c ase a v alue of 0.3 is r ecommended . Figur e 24.20: Mean Trajec tory in a Turbulen t Flow (p.1979 ) illustr ates a discr ete phase tr ajec tory calcu- lation c omput ed without turbulen t disp ersion and Figur e 24.21: Stochastic Trajec tories in a Turbulen t Flow (p.1980 ) illustr ates the “stochastic ” tracking (numb er of tr ies 1) option. When multiple st ochastic tr ajec tory calcula tions ar e performed , the momen tum and mass defined for the injec tion ar e divided e venly among the multiple par ticle/dr oplet tr acks , and ar e ther efore spread out in t erms of the in terphase momen tum, hea t, and mass tr ansf er calcula tions . Including turbulen t disp ersion in y our mo del c an thus ha ve a signific ant impac t on the eff ect of the par ticles on the c ontinuous phase when c oupled c alcula tions ar e performed . Figur e 24.20: Mean Trajec tory in a Turbulen t Flow 1979Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting Initial C onditions f or the D iscrete PhaseFigur e 24.21: Stochastic Trajec tories in a Turbulen t Flow 24.3.18.2. Cloud Track ing For turbulen t flo ws, you c an also include the eff ects of turbulen t disp ersion on the injec tion. Note that cloud tr acking is not a vailable f or the massless par ticle t ype.When cloud tr acking is used , the trajec tory will b e tracked as a cloud of par ticles ab out a mean tr ajec tory, as descr ibed in Particle C loud Tracking in the Theor y Guide . 1.Click the Turbulen t Dispersion tab in the Set Injec tion P roperties dialo g box. 2.Enable cloud tr acking b y tur ning on the Cloud M odel under Cloud Track ing. 3.Specify the minimum and maximum cloud diamet ers. Particles en ter the domain with an initial cloud diamet er equal t o the Min. Cloud D iamet er.The par ticle cloud ’s maximum allo wed diamet er is sp ecified by the Max. Cloud D iamet er. You ma y want to restrict the Max. Cloud D iamet er to a r elevant length sc ale f or the pr oblem t o impr ove computa tional efficienc y in c omple x domains wher e the mean tr ajec tory ma y become stuck in r ecircula tion r egions . Imp ortant Note tha t the cloud mo del is not a vailable f or unst eady par ticle tr acking, and will not allo w you t o use the message passing or h ybrid option f or the par ticles . 24.3.19. Custom P article L aws If the standar d ANSY S Fluen t laws, Laws 1 thr ough 7, do not adequa tely descr ibe the ph ysics of y our discr ete phase mo del, you c an mo dify them b y creating cust om la ws with user-defined func tions . More information ab out user-defined func tions c an b e found in the Fluen t Customiza tion M anual .You c an also cr eate cust om la ws by using a subset of the e xisting ANSY S Fluen t laws (for e xample , Laws 1, 2, and 4), or a c ombina tion of e xisting la ws and user-defined func tions . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1980Modeling D iscrete PhaseOnc e you ha ve defined and loaded y our user-defined func tion(s), you c an cr eate a cust om la w b y en- abling the Custom option under Laws in the Set Injec tion P roperties D ialog Box (p.3917 ).This will op en the Custom La ws Dialog Box (p.3799 ). In the dr op-do wn list t o the lef t of each of the par ticle la ws, you can selec t the appr opriate par ticle la w for y our cust om la w. Each list c ontains the a vailable options that can b e chosen (the standar d laws plus an y user-defined func tions y ou ha ve loaded). Figur e 24.22: The C ustom L aws Dialo g Box There is a final dr op-do wn list in the Custom La ws Dialog Box (p.3799 ) lab eled Switching .You ma y want to ha ve ANSY S Fluen t vary the la ws used dep ending on c onditions in the mo del. You c an cus- tomiz e the w ay ANSY S Fluen t swit ches b etween la ws by selec ting a user-defined func tion fr om this drop-do wn list (see DEFINE_DPM_SWITCH in the Fluen t Customiza tion M anual ). An example of when y ou migh t want to use a cust om la w migh t be to replac e the standar d de volatil- ization la w with a sp ecializ ed de volatiliza tion la w tha t mor e accur ately descr ibes some unique asp ects of y our mo del. After cr eating and loading a user-defined func tion tha t details the ph ysics of y our de- volatiliza tion la w, you w ould visit the Custom La ws Dialog Box (p.3799 ) and r eplac e the standar d de vo- latiliza tion la w (La w 2) with y our user-defined func tion. 24.3.20. Defining P roperties C ommon t o M ore than One Injec tion If you ha ve a numb er of injec tions f or which y ou w ant to set the same pr operties, ANSY S Fluen t provides a shor tcut so tha t you do not need t o visit the Set Injec tion P roperties dialo g box for each injec tion t o mak e the same changes . As descr ibed in Modifying Injec tions (p.1968 ), if y ou selec t mor e than one injec tion in the Injec tions dialo g box, click ing the Set... butt on will op en the Set M ultiple Injec tion P roperties dialo g box (Figur e 24.23: The S et M ultiple Injec tion P roperties D ialog Box (p.1982 )) inst ead of the Set Injec tion Properties dialo g box. 1981Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting Initial C onditions f or the D iscrete PhaseFigur e 24.23: The S et M ultiple Injec tion P roperties D ialo g Box Depending on the t ype of injec tions y ou ha ve selec ted (single , group , atomiz ers, and so on), ther e will be diff erent categor ies of pr operties list ed under Injec tions S etup .The names of these c ategor ies correspond t o the headings within the Set Injec tion P roperties dialo g box (for e xample ,Particle Type and Stochastic Track ing). Only those c ategor ies tha t are appr opriate for all of y our selec ted in- jections (which ar e sho wn in the Injec tions list) will b e list ed. If all of these injec tions ar e of the same type, mor e categor ies of pr operties will b e available f or y ou t o mo dify. If the injec tions ar e of diff erent types, you will ha ve fewer categor ies t o selec t from. Note You c annot define an y pr operties as input par amet ers when y ou ar e mo difying multiple injec tions . If you w ant to sp ecify a pr operty as an input par amet er y ou must use Fig- ure 24.18: The S et Injec tion P roperties D ialog Box (p.1969 ). 24.3.20.1. Mo difying P roperties To mo dify a pr operty, perform the f ollowing st eps: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1982Modeling D iscrete Phase1.Selec t the appr opriate categor y in the Injec tions S etup list. For e xample , if you w ant to set the same flow rate for all of the selec ted injec tions , selec t Point Properties .The dialo g box will e xpand t o sho w the pr operties tha t app ear under tha t heading in the Set Injec tion P roperties dialo g box. 2.Set the pr operty (or pr operties) t o be mo dified , as descr ibed b elow. 3.Click Apply . ANSY S Fluen t will r eport the change in the c onsole windo w. Imp ortant You must click Apply to sa ve the pr operty settings within each c ategor y. If, for e xample , you w ant to mo dify the flo w rate and the st ochastic tr acking par amet ers, you will need to selec t Point Properties in the Injec tions S etup list, specify the flo w rate, and click Apply .You w ould then r epeat the pr ocess f or the st ochastic tr acking par amet ers, click ing Apply again when y ou ar e done . There ar e two types of pr operties tha t can b e mo dified using the Set M ultiple Injec tion P roperties dialo g box. The first t ype involves one of the f ollowing ac tions: •selec ting a v alue fr om a dr op-do wn list •mak ing a selec tion fr om a list of r adio butt ons The sec ond t ype involves one of the f ollowing ac tions: •entering a v alue in a field •enabling / disabling an option Setting the first t ype of pr operty works the same w ay as in the Set Injec tion P roperties dialo g box. For e xample , if y ou selec t Particle Type in the Injec tions S etup list, the dialo g box will e xpand t o show the p ortion of the Set Injec tion P roperties dialo g box wher e you cho ose the par ticle t ype. You c an simply cho ose the desir ed t ype and click Apply . Setting the sec ond t ype of pr operty requir es an additional st ep. If you selec t a c ategor y in the Injec- tions S etup list tha t contains this t ype of pr operty, the e xpanded p ortion of the dialo g box will lo ok like the c orresponding par t of the Set Injec tion P roperties dialo g box, with the addition of Modify check butt ons (see Figur e 24.23: The S et M ultiple Injec tion P roperties D ialog Box (p.1982 )).To change one of the pr operties, first tur n on the Modify check butt on t o its lef t, and then sp ecify the desir ed status or v alue . For e xample , if y ou w ould lik e to enable st ochastic tr acking, first tur n on the Modify check butt on to the lef t of Stochastic M odel.This will mak e the pr operty ac tive so y ou c an mo dify its sta tus.Then, under Property, turn on the Stochastic M odel check butt on. (Be sur e to click Apply when y ou ar e done setting st ochastic tr acking par amet ers.) 1983Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting Initial C onditions f or the D iscrete PhaseIf you w ould lik e to change the v alue of Numb er of Tries, selec t the Modify check butt on t o its lef t to mak e it ac tive, and then en ter the new v alue in the field . Make sur e you click Apply when y ou have finished mo difying the st ochastic tr acking pr operties. Imp ortant The setting f or a pr operty tha t has not b een enabled with the Modify check butt on is not relevant, because it will not b e applied t o the selec ted injec tions when y ou click Apply . After y ou enable Modify for a par ticular pr operty, click ing Apply will mo dify tha t property for all of the selec ted injec tions , so mak e sur e tha t you ha ve the settings the w ay tha t you want them b efore you do this . If you mak e a mistak e, you will ha ve to retur n to the Set Injec tion P roperties dialo g box for each injec tion t o fix the inc orrect setting , if it is not possible t o do so in the Set M ultiple Injec tion P roperties dialo g box. 24.3.20.2. Mo difying P roperties C ommon t o a S ubset of S elec ted Injec tions Note tha t it is p ossible t o change a pr operty tha t is r elevant for only a subset of the selec ted injec tions . For e xample , if some of the selec ted injec tions ar e using st ochastic tr acking and some ar e not , enabling the Random E ddy Lif etime option and click ing Apply will tur n this option on only f or those injec tions that are using st ochastic tr acking.The other injec tions will b e unaff ected. 24.3.21. Point Properties f or Transien t Injec tions Simula tions of tr ansien t par ticles of ten r equir e time dep enden t injec tion c onditions . Potentially most of the p oint properties ma y change o ver time . One metho d to acc omplish this is the use of an Initial- ization func tion as descr ibed in DEFINE_DPM_INJECTION_INIT in the Fluen t Customiza tion Manual . An easier w ay is t o use tr ansien t profiles c ontaining one or mor e variables based on the time or cr ank angle tha t can b e assigned t o various p oint properties: (Total) Mass F low R ate,X-,Y-, Z- Velocity, Velocity M agnitude , and Cone A ngle dep ending on the injec tion t ype selec ted. See Point Properties for S ingle Injec tions (p.1948 ) to Point Properties f or E ffervescent Atomiz er Injec tions (p.1960 ) for the de- scription of the individual pr operties. Before transien t profile v ariables c an b e assigned t o point properties of injec tions , a pr ofile file has t o be read in to ANSY S Fluen t using the File/Read /Profile ... ribbon tab it em. In the Selec t File dialo g box a transien t pr ofile in tabular f ormat with e xtension .ttab has t o be chosen. Alternatively, you can r ead this file in to ANSY S Fluen t using the read-transient-table text command . file → read-transient-table The pr ofile name should not e xceed 63 char acters. See Defining Transien t Cell Z one and B oundar y Conditions (p.1066 ) for the f ormat descr iption. The f ollowing e xample illustr ates an injec tion within 3 intervals of 2.5 millisec onds injec tion time , wher e the sec ond injec tion has an ele vated v elocity. mv-profile 3 13 0 time mass-flow velocity 0 0 0.1 0.00999 0 0.1 0.01 0.001 0.1 0.0125 0.001 0.1 0.01251 0 0.1 0.01999 0 0.1 0.02 0.001 5 0.0225 0.001 5 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1984Modeling D iscrete Phase0.02251 0 0.1 0.02999 0 0.1 0.03 0.001 0.1 0.0325 0.001 0.1 0.03251 0 0.1 For the setting of p oint properties go t o the Point Properties tab in the Set Injec tion P roperties dialo g box. When tr ansien t profiles ar e loaded , you c an cho ose either a constan t metho d (the default) or profile from the Metho d drop-do wn list. If you selec t profile , you also must cho ose a pr ofile fr om the c orres- ponding dr op-do wn list tha t app ears in the Value column. The v ariable angle or time fr om the file is used as an indep enden t interpolation v ariable and c annot b e chosen as a pr ofile . Imp ortant All quan tities in the pr ofile file , including c oordina te values , must b e sp ecified in SI units . Specific ally, Mass F low R ate must b e sp ecified in k g/s,Velocity in m/s , and C one A ngle in radians . ANSY S Fluen t do es not p erform unit c onversion when r eading pr ofile files . 24.4. Setting B oundar y Conditions f or the D iscr ete Phase When a par ticle r eaches a ph ysical b oundar y (for e xample , a w all or inlet b oundar y) in y our mo del, ANSY S Fluen t applies a discr ete phase b oundar y condition t o det ermine the fa te of the tr ajec tory at that boundar y. One of se veral contingencies ma y ar ise: •The par ticle ma y be reflec ted via an elastic or inelastic c ollision. •The par ticle ma y esc ape thr ough the b oundar y.The par ticle is lost fr om the c alcula tion a t the p oint wher e it impac ts the b oundar y. •The par ticle ma y be trapp ed a t the w all. Nonvolatile ma terial is lost fr om the c alcula tion a t the p oint of impac t with the b oundar y; volatile ma terial pr esen t in the par ticle or dr oplet is r eleased t o the v apor phase a t this point. •The par ticle ma y pass thr ough an in ternal b oundar y zone , such as r adia tor or p orous jump . •The par ticle ma y slide along the w all, dep ending on par ticle pr operties and impac t angle . •The par ticle ma y form a film (w all film mo del). You also ha ve the option of implemen ting a user-defined func tion t o mo del the par ticle b ehavior when hitting the b oundar y. More inf ormation ab out user-defined func tions c an b e found in the Fluen t Cus- tomiza tion M anual . The b oundar y condition, or tr ajec tory fate, can b e defined separ ately f or each z one in y our ANSY S Fluen t model. For additional inf ormation, see the f ollowing sec tions: 24.4.1. Discrete Phase B oundar y Condition Types 24.4.2. Default D iscrete Phase B oundar y Conditions 24.4.3. Coefficien ts of R estitution 24.4.4. Friction C oefficien t 1985Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting B oundar y Conditions f or the D iscrete Phase24.4.5. Particle-W all Impingemen t Heat Transf er 24.4.6. Film C ondensa tion M odel 24.4.7. Wall B oundar y La yer M odel 24.4.8. Setting P article E rosion and A ccretion P aramet ers 24.4.1. Discr ete Phase B oundar y Condition Types Discrete phase b oundar y conditions c an b e set f or b oundar ies in the dialo g boxes op ened fr om the Boundar y Conditions task page .When one or mor e injec tions ha ve been defined , inputs f or the discr ete phase will app ear in the dialo g boxes. In the Walls dialo g boxes, you will need t o click the DPM tab to acc ess the Discr ete Phase M odel C onditions as sho wn in Figur e 24.24: Discrete Phase B oundar y Conditions in the Wall D ialog Box (p.1986 ). Figur e 24.24: Discr ete Phase B oundar y Conditions in the Wall D ialo g Box The a vailable b oundar y conditions ar e: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1986Modeling D iscrete Phase•reflec t •trap •escape •wall-jet •wall-film •interior •user-defined Because y ou c an stipula te an y of these c onditions a t flo w b oundar ies, it is p ossible t o inc orporate mixed discr ete phase b oundar y conditions in y our ANSY S Fluen t mo del. Further details ar e discussed in the f ollowing sec tions: 24.4.1.1. The reflec t Boundar y Condition 24.4.1.2. The tr ap B oundar y Condition 24.4.1.3. The esc ape Boundar y Condition 24.4.1.4. The w all-jet B oundar y Condition 24.4.1.5. The w all-film B oundar y Condition 24.4.1.6. The in terior B oundar y Condition 24.4.1.7. The user-defined B oundar y Condition 24.4.1.1. The reflec t Boundar y Condition The par ticle r ebounds off the b oundar y with a change in its momen tum. ANSY S Fluen t provides t wo models f or c omputing this change: •For non-r otating par ticles , the momen tum dep ends on the c oefficien t of r estitution ( Equa tion 16.215 in the Fluent Theor y Guide ). •For rotating par ticles , the mo del pr oposed b y Tsuji et al. 583 is used .The par ticle r otation mo del includes frictional eff ects. The details on these t wo mo dels c an b e found in Wall-P article R eflec tion M odel Theor y in the Fluent Theor y Guide . For inf ormation on ho w to set up the par amet ers f or non-r otating and r otating par ticle mo dels , see Coefficien ts of R estitution (p.1991 ) and Friction C oefficien t (p.1991 ), respectively. When a t least one injec tion acc oun ts for the r ough w all mo del (the Rough Wall M odel option is se- lected under the Physical M odels tab in the Set Injec tions P roperties dialo g box), you c an sp ecify the w all sur face roughness par amet ers as descr ibed in Rough Wall M odel (p.1975 ). 24.4.1.2. The trap Boundar y Condition The tr ajec tory calcula tions ar e termina ted and the fa te of the par ticle is r ecorded as “trapp ed”. In the case of e vaporating dr oplets , their en tire mass instan taneously passes in to the v apor phase and en ters the c ell adjac ent to the b oundar y. See Figur e 24.25: “Trap” Boundar y Condition f or the D iscrete Phase (p.1988 ). In the c ase of c ombusting par ticles , the r emaining v olatile mass is passed in to the v apor phase . 1987Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting B oundar y Conditions f or the D iscrete PhaseFigur e 24.25: “Trap” Boundar y Condition f or the D iscr ete Phase 24.4.1.3. The escape Boundar y Condition The par ticle is r eported as ha ving “escaped” when it enc oun ters the b oundar y in question. Trajec tory calcula tions ar e termina ted. See Figur e 24.26: “Escape” Boundar y Condition f or the D iscrete Phase (p.1988 ). Figur e 24.26: “Escape” Boundar y Condition f or the D iscr ete Phase 24.4.1.4. The wall-jet Boundar y Condition The wall-jet type boundar y condition is appr opriate for high-t emp erature walls wher e no signific ant liquid film is f ormed , and in high-W eber-numb er impac ts wher e the spr ay ac ts as a jet. The mo del is not appr opriate for regimes wher e film is imp ortant (for e xample , port fuel injec tion in SI engines , rainw ater runoff , and so on). A mor e detailed descr iption of under lying theor y is a vailable in Wall-J et M odel Theor y in the Theor y Guide . 24.4.1.5. The wall-film Boundar y Condition For the wall-film boundar y condition, you c an enable and/or set the f ollowing mo dels: •Particle impingemen t/splashing The f ollowing impingemen t mo dels ar e available: –stan ton-r utland : (default) c onsists of f our r egimes , namely , stick, rebound , spread, and splash, which are based on the impac t ener gy and w all temp erature. See The S tanton-R utland M odel in the Fluent Theor y Guide for mor e details . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1988Modeling D iscrete Phase–kuhnk e: consists of f our r egimes spr ead, rebound , splash, and dr y splash (ther mal br eakup). See The Kuhnk e Model in the Fluent Theor y Guide for mor e details .You must sp ecify the f ollowing DPM Wall Roughness P aramet ers: →Roughness R a: is used t o comput e in Equa tion 16.268 in the Fluent Theor y Guide . →Roughness Rz : is used t o comput e splashed dr oplets ejec tion angle in Equa tion 16.280 in the Fluent Theor y Guide . If you w ant to mo del splashing , specify Numb er of S plash D rops (in the Impingemen t/Splashing Model P aramet ers group b ox). A v alue of z ero implies tha t the splashing mo del will not b e used . The Critical Temp erature Factor is used t o det ermine the tr ansition t emp erature (Equa tion 16.232 and Equa tion 16.260 in the Fluent Theor y Guide for the stan ton-r utland and kuhnk e splashing models , respectively). •Film str ipping To mo del film str ipping , enable Particle S tripping and sp ecify Critical S hear S tress (Stripping Model P aramet ers group b ox).When this v alue is e xceeded , mass will b e tak en fr om the film on the fac e wher e liquid film e xists . Optionally , you c an use the f ollowing t ext user in terface commands t o sp ecify : –diamet er coefficien t ( in Equa tion 22.20 in the Theor y Guide (p.1)): define/models/dpm/stripping-options/diameter-coefficient –mass c oefficien t ( in Equa tion 22.21 in the Theor y Guide (p.1)): define/models/dpm/stripping-options/mass-coefficient Imp ortant Particle str ipping c an b e mo deled only if the film c ontains a single par ticle ma terial or a single par ticle-mix ture ma terial.The c ombusting-par ticle t ype is not supp orted. For theor etical inf ormation ab out this option, see Film S tripping in the Fluent Theor y Guide . •Film separ ation You c an selec t from the f ollowing options: –o'rour ke –fouc art (3d only) –friedr ich. Details ab out these mo dels c an b e found in Separ ation C riteria in the Fluent Theor y Guide . You c an also sp ecify : –Critical Weber N umb er: is in Equa tion 22.7 in the Fluent Theor y Guide 1989Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting B oundar y Conditions f or the D iscrete Phase–Film S epar ation A ngle : is θcritical in Equa tion 22.7 in the Fluent Theor y Guide •Film c ondensa tion See Film C ondensa tion M odel (p.1994 ) for details ab out this mo de. •Wall b oundar y layer mo del See Wall B oundar y La yer M odel (p.1996 ) for details . •Particle er osion (DPM mo del with the Erosion/A ccretion option) See Setting P article E rosion and A ccretion P aramet ers (p.1996 ) for details ab out mo deling par ticle erosion. Note Selec ting wall-film aut oma tically enables the Consider C hildr en in the S ame Track ing Step option in the Discr ete Phase M odel dialo g box (Physical M odels tab). Remo ving the Wall Temp eratur e Limit er for L agr angian Wall-F ilm Walls In ANSY S Fluen t, the w all t emp erature is limit ed b y default. The limit is c alcula ted b y Equa tion 16.227 in the Fluent Theor y Guide .You c an r emo ve the w all t emp erature limit b y invoking the f ollowing t ext command: define/models/dpm/options/remove-wall-film-temperature-limiter? Remove the wall film temperature limiter [no]: yes This will r esult in a smo other w all film app earance. However, sinc e the w all t emp erature will not b e limit ed, it ma y introduce instabilities t o the film f ormation pr ocess, and ma y ha ve the eff ect tha t the wall film c omplet ely e vaporates off the w all. If you do use the t emp erature limit in y our simula tion, then y ou ha ve two additional options via the text user in terface (TUI) t o define the t emp erature diff erence ab ove the B oiling p oint and disable the reporting of the L eidenfr ost t emp erature on the w all fac es: define/models/dpm/options/ remove-wall-film-temperature-limiter? Remove the wall film temperature limiter [no]: no Temperature difference above the liquid film boiling point [50]: Report the Leidenfrost temperature on wall film faces [yes]: ANSY S Fluen t will r eport in the c onsole the L eidenfr ost t emp erature as a p ercent of the w all ar ea covered b y film and p ercent of film mass , wher e the w all t emp erature is ab ove the L eidenfr ost p oint. For mor e inf ormation, see Leidenfr ost Temp erature Reporting in the Fluent Theor y Guide . Detailed inf ormation on the w all film mo del c an b e found in Wall-F ilm M odel Theor y in the Fluent Theor y Guide . For a list of limita tions tha t exist with wall-film boundar y conditions , see Limita tions on U sing the Lagr angian Wall F ilm M odel (p.1916 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1990Modeling D iscrete Phase24.4.1.6. The interior Boundar y Condition The interior boundar y condition means tha t the par ticles will pass thr ough the in ternal b oundar y. This option is a vailable only f or in ternal b oundar y zones , such as a r adia tor or a p orous jump . 24.4.1.7. The user -defined Boundar y Condition It is also p ossible t o use a user-defined func tion t o comput e the b ehavior of the par ticles a t a ph ysical boundar y. More inf ormation ab out user-defined func tions c an b e found in the Fluen t Customiza tion Manual . 24.4.2. Default D iscr ete Phase B oundar y Conditions ANSY S Fluen t mak es the f ollowing assumptions r egar ding b oundar y conditions: •The reflec t type is assumed a t wall, symmetr y, and axis b oundar ies, with b oth c oefficien ts of r estitution equal t o 1.0 •The escape type is assumed a t all flo w boundar ies (pr essur e and v elocity inlets , pressur e outlets , and so on) •The interior type is assumed a t all in ternal b oundar ies (r adia tor, porous jump , and so on) The c oefficien t of r estitution c an b e mo dified only f or w all b oundar ies. 24.4.3. Coefficien ts of Restitution A nor mal or tangen tial c oefficien t of r estitution equal t o 1.0 implies tha t the par ticle r etains all of its normal or tangen tial momen tum af ter the r ebound (an elastic c ollision). A nor mal or tangen tial c oeffi- cien t of r estitution equal t o 0.0 implies tha t the par ticle r etains none of its nor mal or tangen tial mo- men tum af ter the r ebound . Nonconstan t coefficien ts of r estitution c an b e sp ecified f or w all z ones with the reflec t type boundar y condition. The c oefficien ts ar e set as a func tion of the impac t angle , , in Particle R eflec tion a t Wall in the Fluent Theor y Guide . Note tha t the default setting f or b oth c oefficien ts of r estitution is a c onstan t value of 1.0 (all nor mal and tangen tial momen tum r etained). If you selec t the reflec t type at a w all (only), you c an define the Normal and Tangen t coefficien ts of restitution under Discr ete Phase Reflec tion C oefficien ts.You c an selec t a constan t,polynomial , piec ewise-linear , or piec ewise-p olynomial func tion fr om the r elevant drop-do wn lists .The dialo g boxes for defining the p olynomial, piec ewise-linear , and piec ewise-p olynomial func tions ar e the same as those used f or defining t emp erature-dep enden t properties.The applied w all hea t transf er mo del assumes tha t a liquid is getting in c ontact with the w all. See Defining P roperties U sing Temp erature- Dependen t Functions (p.1095 ) for details . 24.4.4. Friction C oefficien t When a t least one injec tion acc oun ts for par ticle r otation (the Enable Rota tion option is selec ted under the Physical M odels tab in the Set Injec tions P roperties dialo g box), you c an sp ecify fr iction c oeffi- cien ts for w all z ones with the reflec t type boundar y condition. In the Wall dialo g box, under the DPM 1991Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting B oundar y Conditions f or the D iscrete Phasetab, you c an define the Friction C oefficien t as a constan t or as a polynomial ,piec ewise-linear , or piec ewise-p olynomial func tion. The default v alue f or the constan t is 0.2. For the piec ewise-linear and piec ewise-p olynomial pr ofiles , the fr iction c oefficien t is c omput ed in t erms of the r elative tangen tial v elocity.The default inputs f or these func tions ar e der ived fr om the fr iction c ollision la w (The F riction C ollision La w in the Fluent Theor y Guide ) and ar e as f ollows. •The piec ewise-linear appr oxima tion is defined using the f ollowing default p oints for the r elative (par ticle- to-w all) tangen tial v elocity: –Point 1: 0 m/s –Point 2: 1 m/s –Point 3: 10 m/s –Point 4: 210 m/s •The piec ewise-p olynomial appr oxima tion is defined in the thr ee relative (par ticle-t o-w all) tangen tial v e- locity ranges as f ollows: –Range 1: 0–1 m/s: a quadr atic func tion –Range 2: 1–10 m/s: a constan t –Range 3: 10–210 m/s: a linear func tion For details ab out using the Piecewise-Linear P rofile dialo g box and Piecewise-P olynomial P rofile dialo g box see Inputs f or P iecewise-Linear F unctions (p.1096 ) and Inputs f or P iecewise-P olynomial Functions (p.1098 ), respectively. 24.4.5. Particle-W all Impingemen t Heat Transf er To enable the par ticle-t o-w all hea t exchange f or the reflec t,wall-jet , or wall-film boundar y conditions: In the Wall dialo g box, under the DPM tab , enable the Particle-W all H eat Exchange option. The option is available only f or w all b oundar y conditions and unst eady par ticle tr acking when the ener gy equa tion is enabled . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1992Modeling D iscrete PhaseFigur e 24.27: The Wall D ialo g Box: the P article-W all H eat Exchange Option Note tha t when a par ticle is r eflec ted fr om a w all with the w all film DPM b oundar y condition, the particle-t o-w all hea t exchange is c alcula ted dir ectly b etween the par ticle and the w all. Any wall film presen t is not tak en in to acc oun t. The mo del is applied f or all iner t, droplet , and multic omp onen t par ticles impinging on the w all.The specific mo del is not applied f or the splashed par ticles .When the w all film DPM b oundar y condition is ac tive, the mo del is applied in the R ebound R egime , and it is assumed tha t the par ticles hit the w all irrespective of the pr esenc e of a film. In the S plashing r egime , the mass fr action tha t is dep osited mixes with an y existing film, and the splashed par ticles r etain the impinging dr oplet t emp erature. For c ombusting par ticles , the w all hea t transf er is c alcula ted only if the Wet C ombustion M odel option is enabled in the Set Injec tion P roperties dialo g box, and the par ticle liquid fr action is nonz ero, oth- erwise the Particle-W all H eat Exchange option has no eff ect. See Particle–W all Impingemen t Heat Transf er Theor y in the Fluent Theor y Guide for the under lying theor y and equa tions of the par ticle–w all impingemen t hea t transf er mo del. 1993Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting B oundar y Conditions f or the D iscrete Phase24.4.6. Film C ondensa tion M odel Condensa tion c an b e defined as the tr ansition fr om the gas phase t o the liquid phase as a v apor condenses on a sur face.The ANSY S Fluen t film c ondensa tion mo del is tr igger ed when the par tial pressur e of v apor sp ecies in the bulk gas mix ture exceeds either its v apor pr essur e at the w all-film or, in c ase no film e xists , at the w all t emp erature.When these c onditions ar e met , the v apor sp ecies will c ondense and f orm the liquid film on the w all fac es. The f ollowing limita tions cur rently e xist in the film c ondensa tion mo del: •The film par ticles ar e stagnan t •Only par ticles of a single ma terial (dr oplet or multic omp onen t) can c ondense on a par ticular w all fac e •At least one sp ecies in the mix ture must b e non-c ondensable To use the film c ondensa tion mo del: 1.Enable the f ollowing mo dels: •Ener gy equa tion •Species Transp ort mo del •Unstead y Particle Track ing (in the Discr ete Phase M odel dialo g box) 2.If no dr oplet or multic omp onen t injec tion e xists in the DPM c ase setup , create a c ondensa te injec tion b y selec ting condensa te from the Injec tion Type dropdown list in the Set Injec tion P roperties dialo g box and define the injec tion pr operties as appr opriate. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1994Modeling D iscrete PhaseFigur e 24.28: The S et Injec tion P roperties D ialo g Box: Condensa te Injec tion Note A dr oplet or multic omp onen t injec tion must e xist t o define the v apor–liquid ma terial pair f or the c ondensa tion pr ocess. For fur ther inf ormation, see Injec tion Types (p.1944 ),Point Properties f or C ondensa te Injec tions (p.1963 ), and Defining Injec tion P roperties (p.1969 ). 3.For each dr oplet and multic omp onen t injec tion, specify the c ondensable sp ecies b y selec ting the Evap- orating S pecies . 4.In the Wall dialo g box, under the DPM tab , selec t wall-film from the Boundar y Cond .Type drop-do wn list and enable the Film C ondensa tion option f or each w all wher e condensa tion ma y occur .The F luen t solv er aut oma tically enables the Wall B oundar y Layer M odel. For mor e inf ormation, see Wall B oundar y Layer M odel (p.1996 ). Note Film C ondensa tion is a vailable only with the wall-film DPM b oundar y condition. 5.Enable Linear ized S our ce Terms in the Numer ics tab of the Discr ete Phase M odel dialo g box. Enabling the Linear ized S our ce Terms option helps t o stabiliz e the c ondensa tion solution and is strongly ad visable . 1995Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting B oundar y Conditions f or the D iscrete PhaseWhen the appr opriate conditions e xist, the e vaporating sp ecies y ou ha ve selec ted will c ondense on the w alls tha t ha ve the Film C ondensa tion option enabled f orming either dr oplet or multic omp onen t film par ticles (dep ending on the Particle Type selec ted in the Set Injec tion P roperties dialo g box). For inf ormation ab out the theor y behind the F ilm C ondensa tion mo del, see Film C ondensa tion in the Fluent Theor y Guide . 24.4.7. Wall B oundar y Layer M odel The Wall B oundar y La yer mo del enables the b oundar y layer formula tions f or the mass and hea t transf er equa tions f or film v aporization and b oiling as descr ibed in Film Vaporization and B oiling and Ener gy Transf er fr om the F ilm in the Fluent Theor y Guide . To enable the mo del, selec t Wall B oundar y Layer M odel in the DPM tab of the Wall dialo g box. Note that the b oundar y layer formula tions ar e alw ays used f or b oth c ondensa tion and v aporization r ates when the F ilm C ondensa tion mo del is enabled . 24.4.8. Setting P article E rosion and A ccretion P aramet ers If the Erosion/A ccretion option is selec ted in the Physical M odels tab of the Discrete Phase M odel Dialog Box (p.3360 ) (see Monit oring E rosion/A ccretion of P articles a t Walls (p.1927 )), you c an enable erosion mo dels in the DPM tab of the Wall D ialog Box (p.3549 ) and sp ecify the c orresponding er osion rate par amet ers a t the w alls. Imp ortant The default er osion r ate par amet ers f or each er osion mo del ma y not b e appr opriate for your analy sis and must b e adjust ed based on y our o wn e xperimen tal da ta. The f ollowing mo dels ar e available in ANSY S Fluen t: •Gener ic M odel The er osion r ate of the gener ic mo del is defined in Equa tion 16.324 in the Theor y Guide as a pr oduc t of the mass flux and sp ecified func tions f or the par ticle diamet er, impac t angle , and v elocity exponen t. To sp ecify the er osion par amet ers f or the G ener ic mo del, click Edit... next to Gener ic M odel. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1996Modeling D iscrete PhaseFigur e 24.29: The Gener ic E rosion M odel P aramet ers Dialo g Box In the Gener ic E rosion M odel P aramet ers dialo g box, specify the f ollowing par amet ers using a constan t,polynomial ,piec ewise-linear , or piec ewise-p olynomial func tion: –Impac t Angle F unc tion : in Equa tion 16.324 in the Fluent Theor y Guide . –Diamet er F unc tion : in Equa tion 16.324 in the Fluent Theor y Guide . –Velocity Exponen t Func tion : in Equa tion 16.324 in the Fluent Theor y Guide . See Accretion in the Theor y Guide for a detailed descr iption of these func tions and Defining P roperties Using Temp erature-Dependen t Functions (p.1095 ) for details ab out using the dialo g boxes for defining polynomial, piec ewise-linear , and piec ewise-p olynomial func tions . •Finnie To sp ecify the er osion par amet ers f or the F innie mo del, click Edit... next to Finnie . Figur e 24.30: The Finnie M odel P aramet ers Dialo g Box In the Finnie M odel P aramet ers dialo g box, specify the f ollowing par amet ers: 1997Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting B oundar y Conditions f or the D iscrete Phase–Model C onstan t, k: in Equa tion 16.311 in the Fluent Theor y Guide . –Velocity Exponen t: in Equa tion 16.311 in the Fluent Theor y Guide .The default v alue is 2. The v alue of the Velocity Exponen t is gener ally within the r ange of 2.3 t o 2.5 f or metals . –Angle of M aximum E rosion : the impac t angle b etween the appr oaching par ticle tr ack and the w all a t which the er osion r eaches maximum. For inf ormation ab out the theor y behind the F innie mo del, see Finnie E rosion M odel in the Fluent Theor y Guide . •McLaur y To sp ecify the er osion par amet ers f or the M cLaur y mo del, click Edit... next to McLaur y. Figur e 24.31: The McLaur y M odel P aramet ers Dialo g Box In the McLaur y M odel P aramet ers dialo g box, specify the f ollowing par amet ers: –Model C onstan t, A: in Equa tion 16.315 in the Fluent Theor y Guide . –Velocity Exponen t: in Equa tion 16.315 in the Fluent Theor y Guide . –Transition A ngle : in Equa tion 16.316 and Equa tion 16.317 in the Fluent Theor y Guide . –Impac t Angle C onstan t, b: in Equa tion 16.316 in the Fluent Theor y Guide . –Impac t Angle C onstan t, c: in Equa tion 16.316 in the Fluent Theor y Guide . –Impac t Angle C onstan t, w: in Equa tion 16.317 in the Fluent Theor y Guide . –Impac t Angle C onstan t, x: in Equa tion 16.317 in the Fluent Theor y Guide . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 1998Modeling D iscrete Phase–Impac t Angle C onstan t, y: in Equa tion 16.317 in the Fluent Theor y Guide . See Example of the M cLaur y Erosion M odel C onstan ts in the Fluent Theor y Guide for mor e inf ormation about the M cLaur y mo del par amet ers. For theor etical back ground on the M cLaur y mo del, see McLaur y Erosion M odel in the Fluent Theor y Guide . •Oka To sp ecify the er osion par amet ers f or the O ka mo del, click Edit... next to Oka. Figur e 24.32: The Oka M odel P aramet ers Dialo g Box In the Oka M odel P aramet ers dialo g box, specify the f ollowing par amet ers: –Referenc e Erosion R ate: in Equa tion 16.313 in the Fluent Theor y Guide . –Wall M aterial H ardness : in Equa tion 16.314 in the Fluent Theor y Guide . –Model C onstan t, n1: in Equa tion 16.314 in the Fluent Theor y Guide . –Model C onstan t, n2: in Equa tion 16.314 in the Fluent Theor y Guide . –Velocity Exponen t: in Equa tion 16.313 in the Fluent Theor y Guide . –Diamet er E xponen t: in Equa tion 16.313 in the Fluent Theor y Guide . –Referenc e Diamet er: in Equa tion 16.313 in the Fluent Theor y Guide . –Referenc e Velocity: in Equa tion 16.313 in the Fluent Theor y Guide . See Example of the O ka Erosion M odel C onstan ts in the Fluent Theor y Guide for an e xample of the Oka mo del par amet ers' v alues . For mor e inf ormation on the theor y behind the O ka mo del, see Oka Erosion M odel in the Fluent Theor y Guide . 1999Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting B oundar y Conditions f or the D iscrete Phase•Shear S tress (dense flo ws with the disp erse gr anular phase only) To sp ecify the er osion par amet ers f or the shear str ess mo del, click Edit... next to Shear S tress. Figur e 24.33: The Shear S tress M odel P aramet ers Dialo g Box In the Shear S tress M odel P aramet ers dialo g box, specify the f ollowing par amet ers: –Velocity Exponen t: in Equa tion 16.319 in the Fluent Theor y Guide . –Empir ical M odel C onstan t: in Equa tion 16.319 in the Fluent Theor y Guide . –Solid P hase P ack ing Limit : in Equa tion 16.319 in the Fluent Theor y Guide . This mo del should b e used f or dense multiphase flo w with a disp ersed phase c onsisting of solid particles . For mor e inf ormation on the theor y behind the shear str ess mo del, see Abrasiv e Erosion Caused b y Solid P articles in the Fluent Theor y Guide . •Granular P hase S hielding (dense flo ws with the disp erse gr anular phase only) The gr anular phase shielding as giv en b y Equa tion 16.322 in the Fluent Theor y Guide is alw ays con- sider ed in the shear str ess er osion mo del. If you w ant to include the shielding eff ect in other er osion models tha t are cur rently enabled , selec t Granular P hase S hielding .This option is a vailable only when Shear S tress M odel P aramet ers is selec ted. For mor e inf ormation ab out the theor y behind the w all shielding eff ects in dense flo ws, see Wall Shielding E ffect in D ense F low Regimes in the Fluent Theor y Guide . By default , all er osion mo dels ar e enabled . Imp ortant •The default c onstan ts for the F innie , Oka, and M cLaur y mo dels ha ve been tuned t o ma tch the experimen t descr ibed b y Oka [83] (p.4009 ) in which 326-micr on sand par ticles impac t a c arbon steel w all a t a sp eed of 104 m/s and ther efore are only v alid f or those sp ecific c onditions .You can use the default v alues as a star ting p oint for y our simula tion and then adjust them as needed . •Predic tive capabilities of the er osion mo dels ar e limit ed and str ongly c ase dep enden t. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2000Modeling D iscrete Phase24.5. Particle E rosion C oupled with D ynamic M eshes Under c ertain cir cumstanc es, it is desir able t o comput e not only the par ticle-induc ed w all er osion r ates, but also the ac tual def ormation of the ma terial due t o er osion. The er osion of ma terial fr om the sur face of the w all ma y create lar ge c avities tha t will aff ect par ticula te flo w and er osion pr ocesses and e ventually lead t o ma terial failur e.To acc oun t for changes in the w all's shap e and p osition and f or mor e accur ate predic tions of the er osion r ates, ANSY S Fluen t provides the c apabilit y to couple the er osion r ate solv er with the d ynamic mesh mo del. Gener ally, erosion is a slo w pr ocess, typic ally far slo wer than the pr ocesses on the fluid side . ANSY S Fluen t implemen ts the er osion d ynamic mesh mo del using a quasi-st eady appr oach. During each st ep of the solution pr ocess, the flo w and par ticle er osion simula tions ar e performed as st eady-sta te, wher eas the mesh p osition is up dated b y the d ynamic mesh mo dule using the ph ysical time st ep siz e. When er osion is c oupled with d ynamic meshes , ANSY S Fluen t comput es the mesh def ormation of an individual fac e as: (24.13) wher e, = Wall fac e sp ecific er osion r ate densit y = M esh motion time st ep = Wall ma terial densit y 24.5.1. Preliminar ies Before setting up a c alcula tion of er osion c oupled with the d ynamic mesh mo del, perform the f ollowing steps: 1.Set up a DPM c ase (including defining fluid pr operties, setting b oundar y and c ell z one c onditions , etc.). For inf ormation on setting up a DPM c alcula tion, see Steps f or U sing the D iscrete Phase M odels in the Fluent U ser's G uide (p.1917 ). 2.Set up injec tions as descr ibed in Creating and M odifying Injec tions in the Fluent U ser's G uide (p.1966 ). 3.Create report definitions t o monit or flo w variables . 4.Specify c onvergenc e criteria and solv er controls f or y our simula tion. 5.Initializ e the flo w field and r un the solution. Note tha t you need t o comput e a lar ge numb er of par ticle tr ajec tories in or der t o pr ovide sufficien tly smo oth er osion pa tterns for the d ynamic mesh motion algor ithm. 6.Enable er osion/accr etion on aff ected w alls as descr ibed in Monit oring E rosion/A ccretion of P articles at Walls (p.1927 ) and Setting P article E rosion and A ccretion P aramet ers in the Fluent U ser's G uide (p.1996 ). Onc e er osion/accr etion is enabled , the Erosion D ynamic M esh item app ears in the tr ee under the Setup/M odels/D iscr ete Phase tree br anch. 2001Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Particle E rosion C oupled with D ynamic M eshes7.Perform a c alcula tion f or the er osion r ates. Note Note tha t it is not nec essar y to initializ e the flo w field and c alcula te both flo w and erosion pr ior t o coupling er osion with d ynamic mesh. However, it will sp eed up the er osion d ynamic mesh simula tion if y ou star t from a c onverged flo w field and then f ollow with a first estima tion of the er osion r ates. 8.Onc e the solution is c omplet ed, selec t Stead y in the Genteral task page ( Solver group). Note •Erosion c oupling with d ynamic mesh is a vailable only f or st eady-sta te flo ws due t o being implemen ted via a quasi-st eady appr oach. •You must r un the er osion d ynamic mesh simula tion fr om the Erosion D ynamic M esh Coupling S etup dialo g box only , and not fr om the Run C alcula tion task page or b y using t ext commands . 24.5.2. Procedur e for the E rosion C oupled with D ynamic M esh S etup and Solution 1.Open the Erosion D ynamic M esh C oupling S etup dialo g box and selec t Enable E rosion D ynamic M esh Coupling . Setup → Models → Discr ete Phase → Erosion D ynamic M esh Edit... Figur e 24.34: The Erosion D ynamic M esh C oupling S etup Dialo g Box Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2002Modeling D iscrete Phase2.In the Erosion S ettings group b ox, selec t an appr opriate Referenc e Erosion M odel for y our simula tion and sp ecify the Wall M aterial D ensit y. You c an cho ose fr om the f ollowing er osion mo dels: •finnie (default) •gener ic-mo del •mclaur y •oka For inf ormation ab out these mo dels , refer to Setting P article E rosion and A ccretion P aramet ers in the Fluent U ser's G uide (p.1996 ). Note tha t these mo dels will not b e available if y ou ar e using a UDF t o sp ecify the er osion accr etion rates as descr ibed in DEFINE_DPM_EROSION in the Fluent C ustomization Manual . In this c ase, only udf will app ear in Referenc e Erosion M odel. The w all ma terial densit y is assumed t o be iden tical for all w alls in volved in the er osion c oupled with d ynamic mesh simula tion. Note tha t for Wall M aterial D ensit y, you ma y need t o adjust the default v alue of 2719 k g/m3, which is the densit y of aluminum. 3.(dense flo ws with the disp erse gr anular phase only) I f you w ant to mo del abr asiv e erosion r ates and w all shielding eff ects, selec t Include A brasiv e Erosion E ffects. For mor e inf ormation ab out these mo dels , refer to Modeling E rosion R ates in D ense F lows in the Fluent Theor y Guide . 4.In the Dynamic M esh S ettings group b ox, you c an: •Specify a non-z ero value f or # of S moothing S teps if you w ant to apply smo othing t o the w all er osion rates in the d ynamic mesh mo dule . Smoothing the er osion r ates is r ecommended . For c ases with a lo wer par ticle c oun t, you c an increase the # of S moothing S teps to a v alue gr eater than 1. Note tha t tracking a sufficien t numb er of par ticles in y our simula tion will ensur e no lar ge v ariations in er osion r ate densit y. If you r efine y our mesh b y a fac tor of 2 in each dir ection, you also need t o incr ease the numb er of par ticles b y a fac tor of 4 or mor e. •Enable Automa tic D ynamic M esh S etup (default) The Automa tic D ynamic M esh S etup allo ws for a quick setup of the basic func tionalities needed for an er osion d ynamic mesh c oupled simula tion. Selec ting this option aut oma tically enables Dynamic M esh and the smo othing , local cell r emeshing , local fac e remeshing , and fac e region remeshing metho ds.These metho ds will ensur e tha t the mesh qualit y remains acc eptable dur ing the simula tion. The option also aut oma tically cr eates a d ynamic z one of a User-D efined type for each z one par ticipa ting in the c oupled er osion d ynamic mesh simula tion. The motion of the dynamic z ones is defined b y the **er osion** mesh motion UDF pr ovided b y ANSY S Fluen t. For additional inf ormation, see the f ollowing sec tions: –Specifying the M otion of D ynamic Z ones (p.1345 ) –User-D efined M otion (p.1359 ) –Smoothing M etho ds (p.1268 ) –Local Cell R emeshing M etho d (p.1293 ) 2003Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Particle E rosion C oupled with D ynamic M eshes–Local Remeshing M etho d (p.1292 ) –Face Region R emeshing M etho d (p.1300 ) The aut oma tic d ynamic mesh setup uses the d ynamic mesh metho ds with r easonable defaults , which ma y not b e optimal f or all c ases . If you w ant to mo dify the d ynamic mesh settings af ter the aut oma tic setup has b een c omplet ed, you must first disable Automa tic D ynamic M esh Setup ; other wise , your changes will b e overwritten b y the default settings . Before adjusting the dynamic mesh settings , you should b ecome familiar with the Deform A djac ent Boundar y Layer with Z one and Feature D etection options , which ar e descr ibed in Boundar y La yer S moothing Metho d (p.1282 ) and Feature Detection in the Fluent U ser's G uide (p.1313 ). 5.From the Participa ting Walls selec tion list , selec t walls tha t will b e def ormed due t o par ticle-w all er osion. 6.To set c ontrols f or the er osion d ynamic mesh solv er and then r un the simula tion, click Run E rosion-D y- namic M esh S imula tion… . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2004Modeling D iscrete PhaseFigur e 24.35: The Run E rosion-D ynamic M esh S imula tion Dialo g Box a.In the Mesh M otion Time S etup group b ox, you c an selec t the time st epping metho d to comput e the mesh def ormation fr om Equa tion 24.13 (p.2001 ): •fixed-time-st ep: allo ws you t o sp ecify a c onstan t Time S tep. •variable-time-st ep (default): is aut oma tically det ermined b y the d ynamic mesh solv er based on the f ollowing par amet ers: 2005Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Particle E rosion C oupled with D ynamic M eshesMaximum N ode M ovemen t (% of Wall F ace Length Sc ale) the maximum allo wed c ell def ormation p er meshing st ep. It is sp ecified as a fr action (in percent) of the char acteristic length, which is der ived fr om the c ell w all fac e ar ea. A default of 10% is an acc eptable , conser vative value .To sp eed up the c alcula tion, you c an set this paramet er to a higher v alue . A v alue of 20 t o 30%, or e ven higher , is suitable in most cases . However, because the er osion r ate is c onsider ed t o be constan t dur ing each time step, some er osion r ate variations ma y be lost f or lar ger mesh def ormations .Trial and error ma y be requir ed t o find an optimal v alue f or y our c ase input. Minimum/M aximum Time S tep S ize upp er and lo wer time limits . If you w ant the solv er to use the time st ep c alcula ted b y the d ynamic mesh mo dule , set Maximum Time S tep S ize to a lar ge v alue . During the it eration pr ocess, the solv er adjusts the time st ep based on the maximum node mo vemen t.The solv er will gr adually incr ease the time st ep up t o its maximum value , resulting in a fast er o verall simula tion time . ANSY S Fluen t will r eport the time st ep used in the cur rent iteration in the c onsole and in the Time S tep field . b.In the Simula tion Termina tion group b ox, specify the Total Time of E rosion (in sec onds). The simu- lation st ops when the sp ecified time p eriod ends . c.In the Flow S imula tion C ontrol group b ox, you c an sp ecify : •Iterations p er F low S imula tion : is the numb er of flo w iterations b etween mesh def ormation st eps. This numb er should b e sufficien tly lar ge t o ensur e tha t the flo w simula tion c onverges b etween succ essiv e mesh st eps. •(only when Interaction with C ontinuous P hase is enabled) Solve DPM dur ing F low S imula tion : enforces a tigh ter coupling b etween gas and par ticle phases . During the flo w calcula tion, the par ticle tracker will b e called r egular ly at the fr equenc y sp ecified in DPM I teration In terval in the Discr ete Phase M odel dialo g box. d.If you w ant to aut oma tically sa ve case and da ta files dur ing the c alcula tion, you c an sp ecify a filename and a fr equenc y with which c ase and da ta files should b e sa ved f or p ostpr ocessing or r estar t pur poses in the Autosa ve Files group b ox.When sa ving c ase and da ta files , ANSY S Fluen t app ends the filename that you ha ve pr ovided with @time=flow time . e.Specify the aut osave plot options in the Autosa ve Graphics group b ox. i.If you w ant to captur e images of mesh, contour, or v ector plots a t the sp ecified in tervals f or la ter use (f or e xample , to gener ate anima tions of y our solution o ver time), set the fr equenc y at which your plots will b e sa ved in the Save Plots E very text en try field and click Selec t Graphics .... Note The Selec t Graphics ... butt on b ecomes a vailable only af ter the flo w field has been initializ ed. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2006Modeling D iscrete PhaseFigur e 24.36: The Graphics O bjec ts Dialo g Box A.In the Graphics O bjec ts dialo g box, from the New O bjec t drop-do wn list , selec t the objec t that you w ant to sa ve: •Mesh... opens the Mesh D ispla y Dialog Box (p.3239 ) •Contours ... opens the Contours D ialog Box (p.3790 ) •Vectors... opens the Vectors D ialog Box (p.3954 ) Onc e you cr eate a new objec t, it will b e displa yed in the Graphics O bjec ts dialo g box. B.Selec t which gr aphics objec ts you w ant to sa ve as PNG images dur ing the solution r un. Similar to case and da ta files , the image filenames will b e app ended with @time=flow time . ii.If you w ant ANSY S Fluen t to plot the v ertex maximum of the accumula ted def ormation v ariable on all w alls under going mesh def ormation, enable Automa tic M esh D eformation Rep ort. When y ou star t iterating , ANSY S Fluen t aut oma tically cr eates the max-accumula ted-def orm- ation report definition and max-accumula ted-def ormation-pset report plot , which will b e displa yed in the gr aphics windo w dur ing the solution r un. 7.Click Run... in the Run E rosion-D ynamic M esh S imula tion dialo g box. Imp ortant The er osion d ynamic mesh simula tion must b e run only fr om the Run E rosion-D ynamic Mesh S imula tion dialo g box. During the c oupled er osion d ynamic mesh analy sis, first , the er osion mo dule c omput es er osion rates and passes them t o the d ynamic mesh mo dule .The d ynamic mesh mo dule p erforms a pseudo- steady simula tion of the mesh def ormation. After tha t, the solv er carries out a st eady-sta te flo w calcula tion f or a sp ecified numb er of flo w it erations . If Solve DPM dur ing F low S imula tion is en- abled , the par ticle tr acking is p erformed in the sp ecified DPM I teration In terval. Other wise , the particle tr acker is r un onc e af ter the flo w calcula tion is finished .Whene ver the par ticle tr acker is run, the DPM sour ces ar e up dated.This pr ocess is r epeated un til the sp ecified Total Time O f Erosion is reached . 2007Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Particle E rosion C oupled with D ynamic M eshesAs the solution pr ogresses , ANSY S Fluen t reports the d ynamic mesh time st ep and the simula tion time in the c onsole and the Time S tep and Elapsed S imula tion Time fields . If you in terrupt the simula tion using the Interrupt S imula tion dialo g box, the solv er will c omplet e the cur rent flo w and er osion it erations b efore stopping the c alcula tion. 24.5.3. Postpr ocessing f or E rosion D ynamic M esh C alcula tions You c an gener ate gr aphic al plots or alphanumer ic reports for the mesh def ormation using the f ollowing additional p ostpr ocessing v ariable: •Accumula ted D eformation (in the Mesh... categor y) 24.6. Setting M aterial P roperties f or the D iscr ete Phase In or der t o apply the ph ysical mo dels descr ibed in ear lier sec tions t o the pr edic tion of the discr ete phase tr ajec tories and hea t/mass tr ansf er, ANSY S Fluen t requir es man y ph ysical pr operty inputs . For additional inf ormation, see the f ollowing sec tions: 24.6.1. Summar y of P roperty Inputs 24.6.2. Setting D iscrete-Phase P hysical Properties 24.6.1. Summar y of P roperty Inputs Table 24.1: Property Inputs f or Iner t Particles (p.2008 ) – Table 24.5: Property Inputs f or M ultic omp onen t Particles (La w 7) (p.2011 ) summar ize which of these pr operty inputs ar e used f or each par ticle t ype and in which of the equa tions f or hea t and mass tr ansf er each pr operty input is used . Detailed descr iptions of each input ar e pr ovided in Setting D iscrete-Phase P hysical Properties (p.2011 ). Table 24.1: Property Inputs f or Iner t Particles Symb ol Property in Equa tion 16.1 in the Theor y Guidedensit y in Equa tion 16.93 and Equa tion 16.303 specific hea t in Equa tion 16.12 and in Equa tion 16.304ther mal c onduc tivit y in Equa tion 16.93 particle emissivit y in Equa tion 5.34particle sc attering fac tor in Equa tion 16.11ther mophor etic c oefficien t Table 24.2: Property Inputs f or D roplet P articles Symb ol Properties in Equa tion 16.1 in the Theor y Guidedensit y in Equa tion 16.115 and Equa tion 16.303 specific hea t in Equa tion 16.12 and in Equa tion 16.304ther mal c onduc tivit y in Equa tion 16.380 viscosity Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2008Modeling D iscrete PhaseSymb ol Properties in Equa tion 16.115 ,Equa tion 16.295 , Equa tion 16.296 , and Equa tion 16.310latent hea t in Equa tion 16.100vaporization t emp erature in Equa tion 16.100 ,Equa tion 16.121boiling p oint in Equa tion 16.101 ,Equa tion 16.122volatile c omp onen t fraction in Equa tion 16.105 and in Equa tion 16.289binar y diffusivit y in Equa tion 16.113 in the Fluent Theor y Guidediffusivit y reference pr essur e in Equa tion 16.103saturation v apor pr essur e in Equa tion 16.469heat of p yrolysis in Equa tion 16.349 ,Equa tion 16.379 droplet sur face tension in Equa tion 16.115 ,Equa tion 16.126 particle emissivit y in Equa tion 5.34particle sc attering fac tor in Equa tion 16.208 comp osition a veraging c oefficien t in Equa tion 16.207 temp erature averaging c oefficien t Thermoly sis mo del – single-r ate in Equa tion 16.109 (droplet ma terial) or in Equa tion 16.186 in the Fluent Theor y Guide (multic omp onen t par ticles)pre-exponen tial fac tor in Equa tion 16.109 (droplet ma terial) or in Equa tion 16.186 in the Fluent Theor y Guide (multic omp onen t par ticles)activation ener gy – constan t in Equa tion 16.110 (droplet ma terial) or in Equa tion 16.187 in the Fluent Theor y Guide (multic omp onen t par ticles)rate constan t Table 24.3: Property Inputs f or C ombusting P articles (L aws 1–4) Symb ol Property in Equa tion 16.1 in the Theor y Guidedensit y in Equa tion 16.93 specific hea t in Equa tion 16.12ther mal c onduc tivit y in Equa tion 16.471latent hea t in Equa tion 16.127vaporization t emp erature in Equa tion 16.128volatile c omp onen t fraction 2009Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting M aterial P roperties f or the D iscrete PhaseSymb ol Property in Equa tion 16.160 swelling c oefficien t in Equa tion 16.167burnout st oichiometr ic ratio in Equa tion 16.166combustible fr action in Equa tion 16.181 heat of r eaction f or bur nout in Equa tion 16.181fraction of r eaction hea t giv en t o solid in Equa tion 16.161 ,Equa tion 16.181 particle emissivit y in Equa tion 5.34particle sc attering fac tor in Equa tion 16.11ther mophor etic c oefficien t devolatiliza tion mo del – law 4, constan t rate in Equa tion 16.129 – – c onstan t – law 4, single r ate in Equa tion 16.130 – – pr e-exponen tial fac tor in Equa tion 16.130 – – ac tivation ener gy – law 4, two rates in Equa tion 16.133 ,Equa tion 16.134 – – pr e-exponen tial fac tors in Equa tion 16.133 ,Equa tion 16.134 – – ac tivation ener gies in Equa tion 16.135 – – w eigh ting fac tors – law 4, CPD in Equa tion 16.146 – – initial fr action of br idges in c oal la ttice in Equa tion 16.145 – – initial fr action of char br idges in Equa tion 16.157 – – la ttice coordina tion numb er in Equa tion 16.157– – clust er molecular w eigh t in– – side chain molecular w eigh t Table 24.4: Property Inputs f or C ombusting P articles (L aw 5) Symb ol Property combustion mo del – law 5, diffusion r ate in Equa tion 16.168 in the Theor y Guide– – binar y diffusivit y in Equa tion 16.113 in the Fluent Theor y Guide– – diffusivit y reference pr essur e – law 5, diffusion/k inetic r ate in Equa tion 16.169 – – mass diffusion limit ed r ate constan t in Equa tion 16.170 – – k inetics limit ed r ate pr e-exp. factor Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2010Modeling D iscrete PhaseSymb ol Property in Equa tion 16.170 – – k inetics limit ed r ate ac tivation ener gy – law 5, intrinsic r ate in Equa tion 16.169 – – mass diffusion limit ed r ate constan t in Equa tion 16.179– – k inetics limit ed r ate pr e-exp. factor in Equa tion 16.179– – k inetics limit ed r ate ac tive ener gy in Equa tion 16.176 – – char p orosity in Equa tion 16.178 – – mean p ore radius in Equa tion 16.173 ,Equa tion 16.175– – sp ecific in ternal sur face ar ea in Equa tion 16.176 – – t ortuosit y in Equa tion 16.180 – – bur ning mo de Table 24.5: Property Inputs f or M ultic omp onen t Particles (L aw 7) Symb ol Property selec ted dr oplets f or c omp onen ts mixture sp ecies in Equa tion 16.1 of the Theor y Guidedensit y in Equa tion 16.190 and Equa tion 16.303 specific hea t in Equa tion 16.12 and in Equa tion 16.304ther mal c onduc tivit y in Equa tion 16.184vapor par ticle equilibr ium in Equa tion 16.11ther mophor etic c oefficien t in Equa tion 16.208 comp osition a veraging c oefficien t in Equa tion 16.207 temp erature averaging c oefficien t 24.6.2. Setting D iscr ete-Phase P hysical P roperties 24.6.2.1. The C onc ept of D iscr ete-Phase M aterials When y ou cr eate a par ticle injec tion and define the initial c onditions f or the discr ete phase (as de- scribed in Setting Initial C onditions f or the D iscrete Phase (p.1943 )), you cho ose a par ticular ma terial as the par ticle ’s ma terial. All par ticle str eams of tha t ma terial will ha ve the same ph ysical pr operties. Imp ortant Note tha t you will not cho ose a Material for a Massless par ticle t ype in the Set Injec tions Properties dialo g box. Discrete-phase ma terials ar e divided in to four c ategor ies, corresponding t o the f our t ypes of par ticles available .These ma terial t ypes ar e iner t-par ticle ,droplet-par ticle ,combusting-par ticle , and mul- ticomp onen t-par ticle . Each ma terial t ype will b e added t o the Material Type list in the Create/Edit Materials D ialog Box (p.3386 ) when an injec tion of tha t type of par ticle is defined (in the Set Injec tion Properties or Set M ultiple Injec tion P roperties dialo g box, as descr ibed in Setting Initial C onditions 2011Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting M aterial P roperties f or the D iscrete Phasefor the D iscrete Phase (p.1943 )).The first time y ou cr eate an injec tion of each par ticle t ype, you will be able t o cho ose a ma terial fr om the da tabase , and this will b ecome the default ma terial for tha t type of par ticle .That is, if y ou cr eate another injec tion of the same t ype of par ticle , your selec ted material will b e used f or tha t injec tion as w ell.You ma y cho ose t o mo dify the pr edefined pr operties for y our selec ted par ticle ma terial, if y ou w ant (as descr ibed in Modifying P roperties of an Existing Material (p.1083 )). If you need only one set of pr operties f or each t ype of par ticle , you need not define any new ma terials; you c an simply use the same ma terial for all par ticles . Imp ortant If you do not find the ma terial y ou w ant in the da tabase , you c an selec t a ma terial tha t is close t o the one y ou w ant to use , and then mo dify the pr operties and giv e the ma terial a new name , as descr ibed in Creating a N ew M aterial (p.1086 ). Imp ortant Note tha t a discr ete-phase ma terial t ype will not app ear in the Material Type list in the Create/Edit M aterials dialo g boxes un til you ha ve defined an injec tion of tha t type of particles .This means , for e xample , tha t you c annot define or mo dify an y combusting- particle ma terials un til you ha ve defined a c ombusting par ticle injec tion (as descr ibed in Setting Initial C onditions f or the D iscrete Phase (p.1943 )). For a par ticle-mix ture ma terial t ype, you must selec t the sp ecies in y our mix ture.To do this , click the Edit... butt on ne xt to Mixture Species in the Create/Edit M aterials dialo g box.The Species dialo g box will op en, wher e you will include y our Selec ted S pecies .The selec ted sp ecies will no w be available in the Set Injec tion P roperties dialo g box, under the Comp onen ts tab ( Figur e 24.37: The Comp onen ts Tab (p.2013 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2012Modeling D iscrete PhaseFigur e 24.37: The C omp onen ts Tab 24.6.2.1.1. Defining A dditional D iscr ete-Phase M aterials In man y cases , a single set of ph ysical pr operties (densit y, hea t capacit y, and so on) is appr opriate for each t ype of discr ete phase par ticle c onsider ed in a giv en mo del. Sometimes , however, a single model ma y contain t wo diff erent types of iner t, droplet , combusting par ticles , or multic omp onen t particles (f or e xample , hea vy par ticles and gaseous bubbles or t wo diff erent types of e vaporating liquid dr oplets). In such c ases , it is nec essar y to assign a diff erent set of pr operties t o the t wo (or mor e) diff erent types of par ticles .This is easily acc omplished b y defining t wo or mor e iner t, droplet , or c ombusting par ticle ma terials and using the appr opriate one f or each par ticle injec tion. You c an define additional discr ete-phase ma terials either b y copying them fr om the da tabase or b y creating them fr om scr atch. See Using the Create/Edit M aterials Dialog Box (p.1081 ) for instr uctions on using the Create/Edit M aterials D ialog Box (p.3386 ) to perform these ac tions . Imp ortant Recall tha t you must define a t least one injec tion (as descr ibed in Setting Initial C onditions for the D iscrete Phase (p.1943 )) containing par ticles of a c ertain t ype before you will b e able t o define additional ma terials f or tha t par ticle t ype. 24.6.2.2. Description of the P roperties The pr operties tha t app ear in the Create/Edit M aterials D ialog Box (p.3386 ) vary dep ending on the particle t ype (selec ted in the Set Injec tion P roperties or Set M ultiple Injec tion P roperties dialo g box, as descr ibed in Defining Injec tion P roperties (p.1969 ) and Defining P roperties C ommon t o M ore 2013Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting M aterial P roperties f or the D iscrete Phasethan One Injec tion (p.1981 )) and the ph ysical mo dels y ou ar e using in c onjunc tion with the discr ete- phase mo del. All pr operties y ou ma y need t o define f or a discr ete-phase ma terial ar e list ed b elow (alphab etically). See Table 24.1: Property Inputs f or Iner t Particles (p.2008 ) – Table 24.4: Property Inputs f or C ombusting Particles (La w 5) (p.2010 ) to see which pr operties ar e defined f or each t ype of par ticle . Binar y Diffusivit y is the mass diffusion c oefficien t used in the v aporization la w (La w 2), in Equa tion 16.105 and in Equa tion 16.289 in the Theor y Guide .This input is also used t o define the mass diffusion of the o xidizing species t o the sur face of a c ombusting par ticle , , as giv en in Equa tion 16.168 in the Theor y Guide . (Note tha t the diffusion c oefficien t inputs tha t you supply f or the c ontinuous phase ar e not used f or the discr ete phase .) For Droplet P article type Materials, selec t film-a veraged from the Binar y D iffusivit y drop-do wn list and sp ecify par amet ers f or the film-a veraged mo del (see Equa tion 16.111 in the Theor y Guide ) using the Film Binar y D iffusivit y dialo g box.The film-a veraged mo del is r ecommended when accur ate temp erature-dep enden t binar y diffusivit y da ta ar e available . To apply the unit y Lewis numb er mo del ( Equa tion 16.112 in the Fluent Theor y Guide ) selec t unit y- lewis-numb er from the Binar y D iffusivit y drop-do wn. The unit y Lewis numb er mo del is a sim- plified appr oach and is not appr opriate when the molecular w eigh ts of the e vaporating sp ecies (or o xidizing sp ecies f or c ombusting par ticles) and the gas-phase mix ture ar e very diff erent.The model c an b e applied , for e xample , for the e vaporation of w ater, ligh t hydrocarbons, or methanol in air , but is not appr opriate for hea vy hydrocarbons. You also ha ve the option of implemen ting a user-defined func tion t o mo del the par ticle binar y diffusivit y. See DEFINE_DPM_PROPERTY in the Fluent C ustomization Manual for mor e inf ormation. To enable the pr essur e dep endenc e for the binar y diffusivit y, in the Create/Edit M aterials dialo g box, under Properties , from the Diffusivit y Ref erenc e Pressur e drop-do wn list , selec t constan t (see Equa tion 16.113 in the Fluent Theor y Guide ) and en ter a v alue f or the r eference pr essur e that corresponds t o the v alue defined f or the Binar y D iffusivit y ma terial pr operty.The pr essur e dep endenc e option is a vailable with all pr operty metho ds for the binar y diffusivit y, including user-defined , with the e xception of the unit y Lewis numb er mo del, for which the pr essur e de- pendenc e is alr eady acc oun ted f or thr ough the densit y variable in the mo del equa tion. Boiling P oint is the t emp erature, , at which the c alcula tion of the b oiling r ate equa tion ( Equa tion 16.123 in the Theor y Guide ) is initia ted b y ANSY S Fluen t.When a dr oplet par ticle r eaches the b oiling p oint, ANSY S Fluen t applies La w 3 and assumes tha t the dr oplet t emp erature is c onstan t at .The b oiling p oint denot es the t emp erature at which the par ticle la w tr ansitions fr om the v aporization la w to the b oiling law. For multic omp onen t par ticles the b oiling p oint of the c omp onen ts is used only as a r eference temp erature of the la tent hea t. Inst ead, the b oiling star ts when the sum of the par tial c omp onen t saturation pr essur es reach the t otal fluid pr essur e.The definition of the sa turation pr essur e cur ve is ther efore essen tial f or the b oiling of multic omp onen t par ticles . You also ha ve the option of implemen ting a user-defined func tion t o mo del the par ticle b oiling point. See DEFINE_DPM_PROPERTY in the Fluent C ustomization Manual for mor e inf ormation. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2014Modeling D iscrete PhaseBur nout S toichiometr ic R atio is the st oichiometr ic requir emen t, , for the bur nout r eaction, Equa tion 16.167 in the Theor y Guide , in terms of mass of o xidan t per mass of char in the par ticle . Combustible F raction is the mass fr action of char , , in the c oal par ticle , tha t is, the fr action of the initial c ombusting par ticle that will r eact in the sur face reaction, Law 5 ( Equa tion 16.166 in the Theor y Guide ). Combustion M odel defines which v ersion of the sur face char c ombustion la w (La w5) is b eing used .You c an cho ose fr om the f ollowing options: •diffusion-limit ed (default) The binar y diffusivit y defined ab ove will b e used in Equa tion 16.168 in the Theor y Guide . •kinetics/diffusion-limit ed When the kinetics/diffusion-limit ed limit ed r ate mo del is selec ted f or the sur face combustion model, the Kinetics/D iffusion-Limit ed C ombustion M odel D ialog Box (p.3439 ) opens wher e you can en ter the Mass D iffusion Limit ed R ate Constan t ( in Equa tion 16.169 in the Theor y Guide ),Kinetics Limit ed R ate Pre-exponen tial F actor ( in Equa tion 16.170 ), and Kinetics Limit ed R ate Activation E nergy ( in Equa tion 16.170 ). Note tha t the Kinetics/D iffusion-Limit ed C ombustion M odel dialo g box is a mo dal dialo g box, which means tha t you must t end t o it immedia tely b efore continuing the pr operty defini- tions . •intrinsic-mo del When the intrinsic-mo del is selec ted f or the sur face combustion mo del, the Intrinsic C ombustion Model D ialog Box (p.3440 ) opens wher e you c an en ter the Mass D iffusion Limit ed R ate Constan t ( in Equa tion 16.169 in the Theor y Guide ),Kinetics Limit ed R ate Pre-exponen tial F actor ( in Equa tion 16.179 ),Kinetics Limit ed R ate Activation E nergy ( in Equa tion 16.179 ),Char Porosit y ( in Equa tion 16.176 ),Mean P ore Radius ( in Equa tion 16.178 ),Specific In ternal Surface Area ( in Equa tion 16.173 Equa tion 16.175 ),Tortuosit y ( in Equa tion 16.176 ), and Bur ning M ode, alpha ( in Equa tion 16.180 ). Note tha t the Intrinsic C ombustion M odel dialo g box is a mo dal dialo g box, which means that you must t end t o it immedia tely b efore continuing the pr operty definitions . •multiple-sur face-reac tions When multiple-sur face-reac tions is selec ted, ANSY S Fluen t displa ys the Multiple Sur face Reac- tions D ialog Box (p.3441 ) informing y ou t o op en the Reac tions dialo g box, wher e you c an r eview or mo dify the par ticle sur face reactions tha t you sp ecified as descr ibed in Overview of U ser Inputs for M odeling S pecies Transp ort and R eactions (p.1614 ). In addition, you c an set pr operty options for the char sp ecific hea t and densit y: Comp osition D ependen t Specific H eat if this option is enabled , your input f or the par ticle property will b e used t o det ermine the sp ecific hea t of the v olatiles and ash c omp onen t only .The sp ecific hea t of the char will be calcula ted as a mass-w eigh ted a verage of the par ticle sur face sp ecies sp ecific hea t values , 2015Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting M aterial P roperties f or the D iscrete Phaseand the par ticle sp ecific hea t is finally c alcula ted as the mass a verage of the char and volatiles+ash fr actions .The sp ecific hea t of the par ticle sur face sp ecies should b e defined in the c orresponding fluid ma terials of the M ixture ma terial. Comp osition D ependen t Densit y if this option is enabled , your input f or the par ticle D ensit y pr operty will b e used t o det erm- ine the densit y of the v olatiles and ash c omp onen t.The densit y of the char will b e calcula ted as a v olume-w eigh ted a verage v alue of the par ticle sur face sp ecies densities , and the par ticle densit y is finally c alcula ted as the v olume-w eigh ted a verage of the char and v olatiles+ash fractions .The densit y of the par ticle sur face sp ecies should b e defined in the c orresponding fluid ma terials of the M ixture ma terial. Imp ortant If you ha ve not y et defined an y par ticle sur face reactions , you must b e sur e to define them no w. See Using the M ultiple Sur face Reactions M odel f or D iscrete-Phase P article Combustion (p.1662 ) for mor e inf ormation ab out using the multiple sur face reactions model. You will notic e tha t the Bur nout S toichiometr ic R atio and Heat of Reac tion f or Bur nout are no longer a vailable in the Create/Edit M aterials dialo g box, as these par amet ers ar e no w comput ed fr om the par ticle sur face reactions y ou defined in the Reac tions dialo g box. Note tha t the multiple sur face reactions mo del is a vailable only if the Particle S urface option for Reac tions is enabled in the Species M odel dialo g box. See User Inputs f or P article Sur face Reactions (p.1661 ) for details . Comp osition A veraging C oefficien t, is the c oefficien t in Equa tion 16.208 in the Fluent Theor y Guide .To assume bulk gas c omp osition f or the ph ysical pr operties in the par ticle v aporization and hea ting r ates equa tions , selec t none from the Comp osition A veraging C oefficien t drop-do wn in the Create/Edit M aterials dialo g box, under Properties .To enable pr operty averaging , selec t constan t and en ter a v alue b etween 0 and 1 f or the Comp osition A veraging C oefficien t. = 1 c orresponds t o bulk gas mix ture. For = 0, the c omp osition reverts to the par ticle sur face comp osition. Imp ortant When y ou define the Comp osition A veraging C oefficien t with a constan t value other than 1, you must also sp ecify Specific H eat,Visc osit y and Thermal C onduc tivit y for the e vaporating sp ecies (in the Create/Edit M aterials dialo g box, under Properties , for the c orresponding fluid ma terial of the c ontinuous phase mix ture). Note tha t for the definition of the e vaporating sp ecies pr operties, the user-defined metho d is not supp orted and should not b e used . The default and r ecommended v alue f or the a veraging c oefficien t is 1/3. However, to impr ove the simula tion r esults , you must pr ovide accur ate temp erature-dep enden t da ta for the v apor material (thr ough the Create/Edit M aterials dialo g box). Cp is the sp ecific hea t, , of the par ticle .The sp ecific hea t ma y be defined as a func tion of t emp erature by selec ting one of the func tion t ypes fr om the dr op-do wn list t o the r ight of Cp. See Defining P roperties Using Temp erature-Dependen t Functions (p.1095 ) for details ab out t emp erature-dep enden t properties. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2016Modeling D iscrete PhaseFor multic omp onen t par ticles , it can b e calcula ted as a mass-w eigh ted v alue of the sp ecific hea t of the droplet c omp onen t. You also ha ve the option of implemen ting a user-defined func tion t o mo del the par ticle sp ecific heat. See DEFINE_DPM_PROPERTY in the Fluent C ustomization Manual for mor e inf ormation. A comp osition-dep enden t char sp ecific hea t option c an b e enabled if y ou ar e using the multiple- surface-reactions mo del f or a c ombusting par ticle . For details on enabling this mo del, see Com- bustion M odel (p.2015 ). When y ou ar e using the non-pr emix ed or the par tially-pr emix ed c ombustion mo del in the c on- tinuous phase c alcula tion, the sp ecific hea t defined f or the par ticle ma terial will b e used f or the specific hea t and en thalp y calcula tions of the non-v olatile/non-r eacting par ticle mass . Densit y is the densit y of the par ticula te phase in units of mass p er unit v olume of the discr ete phase .This densit y is the mass densit y and not the v olumetr ic densit y.The densit y ma y be defined as a func tion of t emp er- ature by selec ting one of the func tion t ypes fr om the dr op-do wn list t o the r ight of Densit y. See Defining Properties U sing Temp erature-Dependen t Functions (p.1095 ) for details ab out t emp erature-dep enden t properties. For compr essible flo ws, or if an y of the r eal-gas mo dels is enabled , the compr essible-liquid metho d is also a vailable . See Compr essible Liquid D ensit y Metho d (p.1100 ) for details . For multic omp onen t particles , it can b e calcula ted as a v olume-w eigh ted v alue of the densit y of the dr oplet c omp onen ts. You also ha ve the option of implemen ting a user-defined func tion t o mo del the par ticle densit y. See DEFINE_DPM_PROPERTY in the Fluent C ustomization Manual for mor e inf ormation. For a c ombusting par ticle tha t sw ells dur ing the tr ajec tory calcula tions , the t emp erature-dep enden t densit y calcula tion is susp ended dur ing the de volatiliza tion la w and y our input is used t o det ermine the initial par ticle diamet er, at the star t of the de volatiliza tion in Equa tion 16.160 in the Fluent Theor y Guide . A c omp osition-dep enden t char densit y option c an b e enabled if y ou ar e using the multiple-sur face-reactions mo del f or a c ombusting par ticle . For details on enabling this mo del, see Combustion M odel (p.2015 ). Devolatiliza tion M odel defines which v ersion of the de volatiliza tion mo del, Law 4, is b eing used . You c an cho ose the f ollowing de volatiliza tion mo dels (as descr ibed in Devolatiliza tion (La w 4) in the Theor y Guide ): •constan t (default) To use the default c onstan t rate de volatiliza tion mo del (as descr ibed in Equa tion 16.129 in the Theor y Guide ), enter the r ate constan t in the field b elow the list. •single r ate When the single k inetic r ate mo del is selec ted, the Single R ate M odel D ialog Box (p.3436 ) opens wher e you c an en ter the Pre-exponen tial F actor, , and the Activation E nergy, , to be used in Equa tion 16.131 in the Theor y Guide for the c omputa tion of the k inetic r ate. •two-comp eting-r ates When the t wo comp eting r ates mo del ( two-comp eting-r ates) is selec ted, the Two Comp eting Rates M odel D ialog Box (p.3437 ) opens wher e you c an en ter, for the First R ate and the Second 2017Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting M aterial P roperties f or the D iscrete PhaseRate, the Pre-exponen tial F actor ( in Equa tion 16.133 and in Equa tion 16.134 in the Theor y Guide ),Activation E nergy ( in Equa tion 16.133 and in Equa tion 16.134 ), and Weigh ting F actor ( and in Equa tion 16.135 ).The c onstan ts you sp ecify ar e used in Equa- tion 16.133 through Equa tion 16.135 . •cpd-mo del When the CPD mo del ( cpd-mo del) is selec ted, the CPD M odel dialo g box op ens wher e you can en ter the Initial F raction of Br idges in C oal L attice ( in Equa tion 16.146 of the Theor y Guide), Initial F raction of C har Br idges ( in Equa tion 16.145 ),Lattice Coordina tion N umb er ( in Equa tion 16.157 ),Clust er M olecular Weigh t ( in Equa tion 16.157 ), and Side C hain Molecular Weigh t ( in Equa tion 16.156 ). Note tha t the Single R ate M odel,Two Comp eting R ates M odel, and CPD M odel dialo g boxes are mo dal dialo g boxes, which means tha t you must t end t o them immedia tely b efore continuing the pr operty definitions . Diffusivit y Ref erenc e Pressur e is the r eference pr essur e for the pr essur e dep enden t binar y diffusivit y in Equa tion 16.113 in the Fluent Theor y Guide .To apply the pr essur e dep endenc e, in the Create/Edit M aterials dialo g box, under Properties , from the Diffusivit y Ref erenc e Pressur e drop-do wn list , selec t constan t and en ter a r efer- ence pr essur e value c orresponding t o the v alue f or the Binar y Diffusivit y material pr operty. If none is selec ted fr om the Diffusivit y Ref erenc e Pressur e drop-do wn list , ANSY S Fluen t assumes no pr essur e dep endenc e for the binar y diffusivit y. Heat of P yrolysis is the hea t of the instan taneous p yrolysis r eaction , , tha t the e vaporating/b oiling sp ecies ma y un- dergo when r eleased t o the c ontinuous phase .This input r epresen ts the c onversion of the e vaporating species t o ligh ter comp onen ts dur ing the e vaporation pr ocess.The hea t of p yrolysis should b e sp ecified as a p ositiv e numb er for e xother mic r eaction and as a nega tive numb er for endother mic r eaction. The default v alue of z ero implies tha t the hea t of p yrolysis is not c onsider ed.This input is used in Equa- tion 16.469 in the Theor y Guide . Heat of Reac tion f or Bur nout is the hea t released b y the sur face char c ombustion r eaction, Law 5 ( Equa tion 16.167 in the Theor y Guide ).This par amet er is sp ecified in t erms of hea t release (f or e xample , Joules) p er unit mass of char consumed in the sur face reaction. Latent Heat is the la tent hea t of v aporization, , requir ed f or phase change fr om an e vaporating liquid dr oplet (Equa tion 16.115 ,Equa tion 16.295 ,Equa tion 16.296 , and Equa tion 16.310 in the Theor y Guide ) or f or the evolution of v olatiles fr om a c ombusting par ticle ( Equa tion 16.161 in the Theor y Guide ).This input is supplied in units of J/k g in SI units or of Btu/ in B ritish units and is tr eated as a c onstan t by ANSY S Fluen t. For the dr oplet par ticle , the la tent hea t value a t the b oiling p oint temp erature should b e used . You also ha ve the option of implemen ting a user-defined func tion t o mo del the par ticle la tent heat. See DEFINE_DPM_PROPERTY in the Fluent C ustomization Manual for mor e inf ormation. Reac t. Heat Fraction A bsorb ed b y Solid is the par amet er (Equa tion 16.181 in the Theor y Guide ), which c ontrols the distr ibution of the hea t of reaction b etween the par ticle and the c ontinuous phase .The default v alue of z ero implies tha t the entire hea t of r eaction is r eleased t o the c ontinuous phase . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2018Modeling D iscrete PhaseSaturation Vapor P ressur e is the sa turated v apor pr essur e, , defined as a func tion of t emp erature, which is used in the v aporiz- ation la w, Law 2 ( Equa tion 16.103 in the Theor y Guide ).The sa turated v apor pr essur e ma y be defined as a func tion of t emp erature by selec ting one of the func tion t ypes fr om the dr op-do wn list t o the r ight of its name . (See Defining P roperties U sing Temp erature-Dependen t Functions (p.1095 ) for details ab out temp erature-dep enden t properties.) In the c ase of unr ealistic inputs , ANSY S Fluen t restricts the r ange of to between 0.0 and the op erating pr essur e. Correct specific ation of a r ealistic v apor pr essur e curve is essen tial f or accur ate results fr om the v aporization mo del. You also ha ve the option of implemen ting a user-defined func tion t o mo del the par ticle sa turation vapor pr essur e. See DEFINE_DPM_PROPERTY in the Fluent C ustomization Manual for mor e in- formation. Swelling C oefficien t is the c oefficien t in Equa tion 16.160 in the Theor y Guide , which go verns the sw elling of the c oal particle dur ing the de volatiliza tion la w, Law 4 ( Devolatiliza tion (La w 4) in the Theor y Guide ). A sw elling coefficien t of unit y (the default) implies tha t the c oal par ticle sta ys at constan t diamet er dur ing the de- volatiliza tion pr ocess. You also ha ve the option of implemen ting a user-defined func tion t o mo del the par ticle sw elling coefficien t. See DEFINE_DPM_PROPERTY in the Fluent C ustomization Manual for mor e inf ormation. Temp erature Averaging C oefficien t, is the c oefficien t in Equa tion 16.207 in the Fluent Theor y Guide .To assume bulk gas t emp erature for the ph ysical pr operties in the par ticle v aporization and hea ting r ates equa tions , selec t none from the Temp erature Averaging C oefficien t drop-do wn in the Create/Edit M aterials dialo g box, under Properties .To enable pr operty averaging , selec t constan t and en ter a v alue b etween 0 and 1 f or the Temp erature Averaging C oefficien t. = 1 c orresponds t o bulk gas c onditions . For = 0, the t emp er- ature reverts to the par ticle sur face temp erature. Imp ortant When y ou define the Temp erature Averaging C oefficien t with a constan t value other than 1, you must also define Specific H eat,Visc osit y and Thermal C onduc tivit y for the e vaporating sp ecies (in the Create/Edit M aterials dialo g box, under Properties , for the c orresponding fluid ma terial of the c ontinuous phase mix ture). Note tha t for the definition of the e vaporating sp ecies pr operties, the user-defined metho d is not supp orted and should not b e used . The default and r ecommended v alue f or the a veraging c oefficien t is 1/3. However, to impr ove the simula tion r esults , you must pr ovide accur ate temp erature-dep enden t da ta for the e vaporating vapor ma terial (thr ough the Create/Edit M aterials dialo g box). Thermal C onduc tivit y is the ther mal c onduc tivit y of the par ticle , .This input is sp ecified in units of W/m-K in SI units or in B ritish units and is tr eated as a c onstan t by ANSY S Fluen t. Thermoly sis M odel defines which Thermoly sis mo del is used f or the c alcula tion of the mass tr ansf er of the v aporizing sp ecies from the dr oplet t o the bulk phase acc ording t o a Thermoly sis r ate equa tion. You c an cho ose fr om the following options: 2019Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting M aterial P roperties f or the D iscrete Phase•single-r ate When single-r ate is selec ted, the Single R ate M odel D ialog Box (p.3436 ) opens wher e you sp ecify the Pre-exponen tial F actor and the Activation E nergy to be used in Equa tion 16.109 (if you ar e mo delling a dr oplet ma terial), or the Pre-exponen tial F actor and Activation E nergy in Equa tion 16.186 in the Fluent Theor y Guide (if y ou ar e mo delling multic omp onen t par ticles). •constan t For the c onstan t rate Thermoly sis mo del, enter the r ate constan t to be used in Equa tion 16.110 (if you ar e mo delling a dr oplet ma terial), or the r ate constan t in Equa tion 16.187 in the Fluent Theor y Guide (if y ou ar e mo delling multic omp onen t par ticles). none (default) signifies tha t the Thermoly sis r ate mo del is disabled . Note tha t if y ou ar e using a multic omp onen t par ticle , the Thermoly sis mo del is set f or the indi- vidual dr oplet ma terials. A typic al applic ation is the mo deling of S elec tive Catalytic R educ tion (SCR) sy stems wher e it is r ecommended t o use the single-r ate Thermoly sis mo del f or the ur ea-liquid comp onen t in the ur ea-w ater par ticle mix ture. Thermophor etic C oefficien t is the c oefficien t in Equa tion 16.11 in the Theor y Guide , and app ears when the ther mophor etic force (which is descr ibed in Thermophor etic F orce in the Theor y Guide ) is included in the tr ajec tory calcula tion (tha t is, when the Thermophor etic F orce option is enabled in the Discr ete Phase M odel dialo g box).The default is the e xpression de velop ed b y Talbot [130] (p.4012 ) (talb ot-diffusion-c oeff) and r equir es no input fr om y ou.You c an also define the ther mophor etic c oefficien t as a func tion of temp erature by selec ting one of the func tion t ypes fr om the dr op-do wn list t o the r ight of Thermophor- etic C oefficien t. See Defining P roperties U sing Temp erature-Dependen t Functions (p.1095 ) for details about t emp erature-dep enden t properties. You also ha ve the option of implemen ting a user-defined func tion t o mo del the par ticle ther mo- phor etic c oefficien t. See DEFINE_DPM_PROPERTY in the Fluent C ustomization Manual for mor e information. Vaporization Temp erature is the t emp erature, , at which the c alcula tion of v aporization fr om a liquid dr oplet or de volatiliza tion from a c ombusting par ticle is initia ted b y ANSY S Fluen t. Until the par ticle t emp erature reaches , the particle is hea ted via La w 1, Equa tion 16.93 in the Theor y Guide .This t emp erature input r epresen ts a modeling decision r ather than an y ph ysical char acteristic of the discr ete phase . You also ha ve the option of implemen ting a user-defined func tion t o mo del the par ticle v aporiz- ation t emp erature. See DEFINE_DPM_PROPERTY in the Fluent C ustomization Manual for mor e information. Vapor-P article-E quilibr ium is the selec ted appr oach f or the c alcula tion of the v apor concentration of the c omp onen ts at the sur face. This c an b e Raoult ’s law (Equa tion 16.198 in the Theor y Guide ), the P eng-R obinson r eal gas mo del (Equa tion 16.206 in the Theor y Guide ), or a user-defined func tion tha t defines the equilibr ium. Vaporization/B oiling M odel defines which v aporization/b oiling mo del is used f or pur e dr oplets (La w 2) and f or multic omp onen t droplets (La w 7). You c an cho ose fr om the f ollowing options: •diffusion-c ontrolled (default) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2020Modeling D iscrete PhaseThis option will apply Equa tion 16.102 in the Theor y Guide . •convection/diffusion-c ontrolled When y ou selec t the convection/diffusion-c ontrolled mo del f or v aporization, Equa tion 16.107 in the Theor y Guide will b e applied f or the c alcula tion of the v aporization r ate, and Equa- tion 16.119 in the Theor y Guide will b e applied in the par ticle hea t transf er calcula tions This model is r ecommended when e vaporation r ates ar e high. For slo wly e vaporating dr oplets b oth models ar e expected t o giv e similar r esults . Onc e you ha ve selec ted convection/diffusion-c ontrolled , you c an enable the Variable L ewis Numb er F ormula tion option in the Model Options dialo g box to comput e the S palding hea t numb er fr om Equa tion 16.118 in the Fluent Theor y Guide . If the option is disabled ANSY S Fluen t uses Equa tion 16.119 . You c an also enable a veraging of the S palding hea t transf er term for the c onvection/diffusion- controlled mo del acc ording t o Equa tion 16.120 in the Fluent Theor y Guide by using the TUI command define/models/dpm/options/vaporization-heat-transfer-aver- aging .This option has the net eff ect of incr easing the hea t-transf er to the dr oplet and ma y produce mor e realistic r esults f or c ases with lar ge t emp erature diff erences b etween dr oplet and bulk gas . For b oth diffusion-c ontrolled and c onvection/diffusion-c ontrolled mo dels , you c an selec t Use the Specific H eat of the E vaporating S pecies in B oiling L aw in the Model Options D ialog Box (p.3405 ). This option sets the hea t capacit y of the gas ( in Equa tion 16.123 in the Fluent Theor y Guide ) to the sp ecific hea t of the e vaporating sp ecies selec ted in the Set Injec tion P roperties dialo g box. For the c onvection/diffusion c ontrolled mo del with the Variable L ewis N umb er F ormula tion , this option is selec ted b y default. This ensur es c onsist ency with the c onvection/diffusion c ontrolled model e xpression f or in Equa tion 16.117 in the Fluent Theor y Guide . Volatile C omp onen t Fraction ( ) is the mass fr action of a dr oplet par ticle tha t ma y vaporize via La ws 2 and/or 3 ( Droplet Vaporization (Law 2) in the Theor y Guide ). For combusting par ticles , it is the mass fr action of v olatiles tha t ma y be evolved via La w 4 ( Devolatiliza tion (La w 4) in the Theor y Guide ). When the eff ect of par ticles on r adia tion is enabled (f or the P-1 or discr ete or dina tes radia tion mo del only) in the Discrete Phase M odel D ialog Box (p.3360 ), you must define the f ollowing additional par a- met ers: Particle E missivit y is the emissivit y of par ticles in y our mo del, , used t o comput e radia tion hea t transf er to the par ticles (Equa tion 16.93 ,Equa tion 16.115 ,Equa tion 16.126 ,Equa tion 16.161 , and Equa tion 16.181 in the Theor y Guide ) when the P-1 or discr ete or dina tes radia tion mo del is ac tive. Note tha t you must enable r adia tion to par ticles , using the Particle R adia tion In teraction option in the Discrete Phase M odel D ialog Box (p.3360 ). Recommended v alues of par ticle emissivit y are 1.0 f or coal par ticles and 0.5 f or ash [70] (p.4008 ). You also ha ve the option of implemen ting a user-defined func tion t o mo del the par ticle emissivit y. See DEFINE_DPM_PROPERTY in the Fluent C ustomization Manual for mor e inf ormation. Particle Sc attering F actor is the sc attering fac tor, , due t o par ticles in the P-1 or discr ete or dina tes radia tion mo del ( Equa tion 5.34 in the Theor y Guide ). Note tha t you must enable par ticle eff ects in the r adia tion mo del, using the Particle Radia tion In teraction option in the Discrete Phase M odel D ialog Box (p.3360 ).The r ecommended v alue 2021Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting M aterial P roperties f or the D iscrete Phaseof for coal c ombustion mo deling is 0.9 [70] (p.4008 ). Note tha t if the eff ect of par ticles on r adia tion is enabled , scattering in the c ontinuous phase will b e ignor ed in the r adia tion mo del. You also ha ve the option of implemen ting a user-defined func tion t o mo del the par ticle sc attering factor. See DEFINE_DPM_PROPERTY in the Fluent C ustomization Manual for mor e inf ormation. When an a tomiz er injec tion mo del and/or the dr oplet br eakup or c ollision mo del is enabled in the Set Injec tion P roperties D ialog Box (p.3917 ) (atomiz ers) and/or Discrete Phase M odel D ialog Box (p.3360 ) (droplet br eakup/c ollision), you must define the f ollowing additional par amet ers: Droplet S urface Tension is the dr oplet sur face tension, .The sur face tension ma y be defined as a func tion of t emp erature by selec ting one of the func tion t ypes fr om the dr op-do wn list t o the r ight of Droplet S urface Tension . See Defining P roperties U sing Temp erature-Dependen t Functions (p.1095 ) for details ab out t emp erature- dep enden t properties.You also ha ve the option of implemen ting a user-defined func tion t o mo del the droplet sur face tension. More inf ormation ab out user-defined func tions c an b e found in the Fluen t Customiza tion M anual . Visc osit y is the dr oplet visc osity, .The visc osity ma y be defined as a func tion of t emp erature by selec ting one of the func tion t ypes fr om the dr op-do wn list t o the r ight of Visc osit y. See Defining P roperties U sing Temp erature-Dependen t Functions (p.1095 ) for details ab out t emp erature-dep enden t properties.You also ha ve the option of implemen ting a user-defined func tion t o mo del the dr oplet visc osity. More in- formation ab out user-defined func tions c an b e found in the Fluen t Customiza tion M anual . 24.7. Solution S trategies f or the D iscr ete Phase Solution of the discr ete phase implies in tegration in time of the f orce balanc e on the par ticle ( Equa- tion 16.1 in the Theor y Guide ) to yield the par ticle tr ajec tory. As the par ticle is mo ved along its tr ajec tory, heat and mass tr ansf er b etween the par ticle and the c ontinuous phase ar e also c omput ed via the heat/mass tr ansf er la ws (Laws for H eat and M ass Ex change in the Theor y Guide ).The accur acy of the discr ete phase c alcula tion ther efore dep ends on the time accur acy of the in tegration and up on the appr opriate coupling b etween the discr ete and c ontinuous phases when r equir ed. Numer ical controls are descr ibed in Numer ics of the D iscrete Phase M odel (p.1937 ). Coupling and p erforming tr ajec tory calcula tions ar e descr ibed in Performing Trajec tory Calcula tions (p.2022 ).Resetting the In terphase Ex change Terms (p.2027 ) and Parallel P rocessing f or the D iscrete Phase M odel (p.2066 ) provide inf ormation ab out resetting in terphase e xchange t erms and using the par allel solv er for a discr ete phase c alcula tion. For additional inf ormation, see the f ollowing sec tions: 24.7.1. Performing Trajec tory Calcula tions 24.7.2. Resetting the In terphase Ex change Terms 24.7.1. Performing Trajec tory Calcula tions The tr ajec tories of y our discr ete phase injec tions ar e comput ed when y ou displa y the tr ajec tories using graphics or when y ou p erform solution it erations .That is, you c an displa y trajec tories without impac ting the c ontinuous phase , or y ou c an include their eff ect on the c ontinuum (t ermed a c oupled c alcula tion). In turbulen t flo ws, trajec tories c an b e based on mean (time-a veraged) c ontinuous phase v elocities or they can b e impac ted b y instan taneous v elocity fluc tuations in the fluid .This sec tion descr ibes the procedur es and c ommands y ou use t o perform coupled or unc oupled tr ajec tory calcula tions , with or without st ochastic tr acking or cloud tr acking. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2022Modeling D iscrete Phase24.7.1.1. Unc oupled C alculations For the unc oupled c alcula tion, you will p erform the f ollowing t wo steps: 1.Solve the c ontinuous phase flo w field . 2.Plot (and r eport) the par ticle tr ajec tories f or discr ete phase injec tions of in terest. In the unc oupled appr oach, this t wo-st ep pr ocedur e complet es the mo deling eff ort, as illustr ated in Figur e 24.38: Uncoupled D iscrete Phase C alcula tions (p.2023 ).The par ticle tr ajec tories ar e comput ed as the y are displa yed, based on a fix ed c ontinuous-phase flo w field . Graphic al and r eporting options are detailed in Postpr ocessing f or the D iscrete Phase (p.2027 ). Figur e 24.38: Uncoupled D iscr ete Phase C alcula tions This pr ocedur e is adequa te when the discr ete phase is pr esen t at a lo w mass and momen tum loading , in which c ase the c ontinuous phase is not impac ted b y the pr esenc e of the discr ete phase . 24.7.1.2. Coupled C alculations In a c oupled t wo-phase simula tion, ANSY S Fluen t mo difies the t wo-st ep pr ocedur e ab ove as f ollows: 1.Solve the c ontinuous phase flo w field (pr ior t o introduc tion of the discr ete phase). 2.Introduce the discr ete phase b y calcula ting the par ticle tr ajec tories f or each discr ete phase injec tion. 3.Recalcula te the c ontinuous phase flo w, using the in terphase e xchange of momen tum, hea t, and mass determined dur ing the pr evious par ticle c alcula tion. 4.Recalcula te the discr ete phase tr ajec tories in the mo dified c ontinuous phase flo w field . 5.Repeat the pr evious t wo steps un til a c onverged solution is achie ved in which b oth the c ontinuous phase flow field and the discr ete phase par ticle tr ajec tories ar e unchanged with each additional c alcula tion. This c oupled c alcula tion pr ocedur e is illustr ated in Figur e 24.39: Coupled D iscrete Phase C alcula- tions (p.2024 ).When y our ANSY S Fluen t mo del includes a high mass and/or momen tum loading in the discr ete phase , the c oupled pr ocedur e must b e followed in or der t o include the imp ortant impac t of the discr ete phase on the c ontinuous phase flo w field . 2023Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Solution S trategies f or the D iscrete PhaseFigur e 24.39: Coupled D iscr ete Phase C alcula tions Imp ortant When y ou p erform coupled c alcula tions , all defined discr ete phase injec tions will b e comput ed.You c annot c alcula te a subset of the injec tions y ou ha ve defined . If ther e ar e massless par ticle injec tions defined , these will ha ve no eff ect in the c oupled c alcula tion. 24.7.1.2.1. Procedur es for a C oupled Two-P hase F low If your ANSY S Fluen t mo del includes pr edic tion of a c oupled t wo-phase flo w, you should b egin with a par tially (or fully) c onverged c ontinuous-phase flo w field .You will then cr eate your injec tion(s) and set up the c oupled c alcula tion. For each discr ete-phase it eration, ANSY S Fluen t comput es the par ticle/dr oplet tr ajec tories and up dates the in terphase e xchange of momen tum, hea t, and mass in each c ontrol volume .These in terphase exchange t erms then impac t the c ontinuous phase when the c ontinuous phase it eration is p erformed . During the c oupled c alcula tion, ANSY S Fluen t will p erform the discr ete phase it eration a t sp ecified intervals dur ing the c ontinuous-phase c alcula tion. The c oupled c alcula tion c ontinues un til the c on- tinuous phase flo w field no longer changes with fur ther c alcula tions (tha t is, all c onvergenc e cr iteria are sa tisfied). When c onvergenc e is r eached , the discr ete phase tr ajec tories no longer change either , sinc e changes in the discr ete phase tr ajec tories w ould r esult in changes in the c ontinuous phase flow field . The st eps f or setting up the c oupled c alcula tion ar e as f ollows: 1.Solve the c ontinuous phase flo w field . 2.In the Discrete Phase M odel D ialog Box (p.3360 ) (Figur e 24.1: The D iscrete Phase M odel D ialog Box and the Tracking P aramet ers (p.1923 )), enable the Interaction with C ontinuous P hase option. 3.Set the fr equenc y with which the par ticle tr ajec tory calcula tions ar e introduced in the DPM I teration Interval field . If you set this par amet er to 5, for e xample , a discr ete phase it eration will b e performed every fifth continuous phase it eration. The optimum numb er of it erations b etween tr ajec tory calcula tions dep ends up on the ph ysics of y our ANSY S Fluen t mo del. Imp ortant Note tha t if y ou set this par amet er to 0, ANSY S Fluen t will not p erform an y discr ete phase it erations . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2024Modeling D iscrete PhaseDuring the c oupled c alcula tion (which y ou initia te using the Run C alcula tion Task P age (p.3640 ) in the usual manner) y ou will see the f ollowing inf ormation in the ANSY S Fluen t console as the c ontinu- ous and discr ete phase it erations ar e performed: iter continuity x-velocity y-velocity k epsilon energy time/it 314 2.5249e-01 2.8657e-01 1.0533e+00 7.6227e-02 2.9771e-02 9.8181e-03 :00:05 315 2.7955e-01 2.5867e-01 9.2736e-01 6.4516e-02 2.6545e-02 4.2314e-03 :00:03 DPM Iteration .... number tracked= 9, number escaped= 1, aborted= 0, trapped= 0, evaporated = 8,i Done. 316 1.9206e-01 1.1860e-01 6.9573e-01 5.2692e-02 2.3997e-02 2.4532e-03 :00:02 317 2.0729e-01 3.2982e-02 8.3036e-01 4.1649e-02 2.2111e-02 2.5369e-01 :00:01 318 3.2820e-01 5.5508e-02 6.0900e-01 5.9018e-02 2.6619e-02 4.0394e-02 :00:00 Note tha t you c an p erform a discr ete phase c alcula tion a t an y time b y using the solve/dpm-update text command . 24.7.1.2.2. Stochastic Track ing in C oupled C alculations If you include the st ochastic pr edic tion of turbulen t disp ersion in the c oupled t wo-phase flo w calcu- lations , the numb er of st ochastic tr ies applied each time the discr ete phase tr ajec tories ar e in troduced during c oupled c alcula tions will b e equal t o the Numb er of Tries specified in the Set Injec tion Properties D ialog Box (p.3917 ). For tr ansien t par ticle tr acking, the numb er of tr ies is set t o 1. Input of this par amet er is descr ibed in Stochastic Tracking (p.1978 ). An input of requests stochastic trajec tory calcula tions f or each par ticle in the injec tion. When the numb er of st ochastic tr acks included is small, you ma y find tha t the ensemble a verage of the tr ajec tories is quit e diff erent each time the trajec tories ar e comput ed.These diff erences ma y, in tur n, impac t the c onvergenc e of y our c oupled solution. For go od convergenc e of a c oupled solution, a sta tistic al indep enden t distr ibution of tr acks can b e achie ved with an adequa te numb er of st ochastic tr acks and/or a sufficien t numb er of diff erent starting lo cations of the tr acks . 24.7.1.2.3. Under -Relaxation of the Int erphase E xchange Terms When y ou ar e coupling the discr ete and c ontinuous phases using the c alcula tion pr ocedur es not ed above, ANSY S Fluen t applies under-r elaxa tion t o the momen tum, hea t, and mass tr ansf er terms.This under-r elaxa tion ser ves to incr ease the stabilit y of the c oupled c alcula tion pr ocedur e by letting the impac t of the discr ete phase change only gr adually : (24.14) wher e is the e xchange t erm, is the pr evious v alue , is the newly c omput ed v alue , and is the par ticle/dr oplet under-r elaxa tion fac tor. For , ANSY S Fluen t uses a default v alue of 0.5 for all t ypes of analy sis e xcept tr ansien t flo ws with unst eady par ticle tr acking, in which c ase the default value of 0.9 is used .You c an mo dify by changing the v alue in the Discr ete Phase S our ces field under Under-Relaxa tion F actors in the Solution C ontrols task page .You ma y need t o decr ease in or der t o impr ove the stabilit y of c oupled discr ete phase c alcula tions . Figur e 24.40: Effect of N umb er of S ource Term U pdates on S ource Term A pplied t o Flow Equa- tions (p.2026 ) sho ws ho w the sour ce term , when applied t o the flo w equa tions , changes with the numb er of up dates for v arying under-r elaxa tion fac tors . Each DPM it eration star ts with an initial value f or the sour ce term, which is t ypic ally z ero at the b eginning of the c alcula tion. After a numb er of up dates, the sour ce term reaches its final value . 2025Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Solution S trategies f or the D iscrete PhaseFigur e 24.40: Effect of N umb er of S our ce Term U pdates on S our ce Term A pplied t o Flow Equa tions Supp ose tha t in a c ontinuous flo w simula tion with c ontinuous DPM tr acking, the DPM under-r elaxa tion factor is chosen t o be 0.5, with 20 c ontinuous phase it erations p er DPM it eration. From Figur e 24.40: Ef- fect of N umb er of S ource Term U pdates on S ource Term A pplied t o Flow Equa tions (p.2026 ), we see that appr oxima tely 10 sour ce term up dates ar e requir ed f or the DPM sour ces to reach their final values .Therefore, in this e xample , at least 200 c ontinuous phase it erations ar e requir ed af ter an y change t o the DPM sour ces (f or e xample , a new injec tion or a changed DPM mass flo w rate), to ensur e that the change has tak en eff ect. For c ases with c onvergenc e difficulties , reducing the under-r elaxa tion fac tors is of ten nec essar y in order t o impr ove the stabilit y of the c oupled DPM simula tion. However, for small v alues of , man y iterations ma y be needed f or the DPM sour ce to reach the final value .You c an use a t ext command that linear ly ramps up the DPM sour ce term to its maximum value . At the end of each it eration , the sour ce term is c omput ed as: With this appr oach, even small v alues f or under-r elaxa tion fac tors c an b e applied , and the final value c an b e reached within a r easonable it eration c oun t. For the ab ove example , a minimum of two sour ce term up dates is r equir ed t o reach the final v alues . Accordingly , it will tak e only 40 c on- tinuous phase it erations t o fully acc oun t for the eff ect of the DPM sour ce changes . To use the linear gr owth of DPM sour ce term func tionalit y, use the f ollowing t ext commands: define/models/dpm/interaction/linear-growth-of-dpm-source-term? Change the DPM source term linearly every DPM iteration [no] y Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2026Modeling D iscrete PhaseNote tha t the impac t of this option is c ase dep enden t. 24.7.2. Resetting the In terphase E xchange Terms If you ha ve performed c oupled c alcula tions , resulting in nonz ero in terphase sour ces/sinks of momen tum, heat, and/or mass tha t you do not w ant to include in subsequen t calcula tions , you c an r eset these sour ces to zero. Solution → Initializa tion Reset DPM S our ces When y ou selec t Reset DPM S our ces, the sour ces will immedia tely b e reset t o zero without an y fur ther confir mation fr om y ou. 24.8. Postpr ocessing f or the D iscr ete Phase After y ou ha ve complet ed y our discr ete phase inputs and an y coupled t wo-phase c alcula tions of in terest, you c an displa y and st ore the par ticle tr ajec tory pr edic tions . ANSY S Fluen t provides b oth gr aphic al and alphanumer ic reporting facilities f or the discr ete phase , including the f ollowing: •graphic al displa y of the par ticle tr ajec tories •summar y reports of tr ajec tory fates •step-b y-step r eports of the par ticle p osition, velocity, temp erature, and diamet er •alphanumer ic reports and gr aphic al displa y of the in terphase e xchange of momen tum, hea t, and mass •optionally , alphanumer ic reports and gr aphic al displa y of v arious c ell-a veraged discr ete phase field v ariables •sampling of tr ajec tories a t boundar ies and lines/planes •summar y reporting of cur rent par ticles in the domain •histograms of tr ajec tory da ta at sample planes •displa y of er osion/accr etion r ates •exporting of tr ajec tories t o Fieldview and Ensigh t This sec tion pr ovides detailed descr iptions of each of these p ostpr ocessing options . (Note tha t plotting or r eporting tr ajec tories do es not change the sour ce terms.) For additional inf ormation, see the f ollowing sec tions: 24.8.1. Displa ying of Trajec tories 24.8.2. Reporting of Trajec tory Fates 24.8.3. Step-b y-Step R eporting of Trajec tories 24.8.4. Reporting of C urrent Positions f or U nsteady Tracking 24.8.5. Reporting of In terphase Ex change Terms (D iscrete Phase S ources) 24.8.6. Reporting of D iscrete Phase Variables 24.8.7. Reporting of U nsteady DPM S tatistics 24.8.8. Sampling of Trajec tories 24.8.9. Hist ogram R eporting of S amples 2027Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Postpr ocessing f or the D iscrete Phase24.8.10. Summar y Reporting of C urrent Particles 24.8.11. Postpr ocessing of E rosion/A ccretion R ates 24.8.12. Assessing the R isk f or Solids D eposit F ormation D uring S elec tive Catalytic R educ tion P rocess 24.8.1. Displa ying of Trajec tories When y ou ha ve defined discr ete phase par ticle injec tions , as descr ibed in Setting Initial C onditions f or the D iscrete Phase (p.1943 ), you c an displa y the tr ajec tories of these discr ete par ticles using the Particle Tracks D ialog Box (p.3881 ) (Figur e 24.41: The P article Tracks D ialog Box (p.2029 )). You c an cr eate named par ticle tr ack definitions and sa ve them f or lat er use . See Creating and U sing C ont our Plot D efinitions (p.2792 ) for additional inf ormation on gr aphics objec t definitions . Note that par ticle tr ack definitions c an b e included in sc enes as long as the XY P lot option is not enabled . See Displa ying a Sc ene (p.2812 ) for additional inf ormation on sc enes . Results → Graphics → Particle Tracks Edit... You c an also cr ate a named par ticle tr ack plot definition and sa ve it f or la ter use . Results → Graphics → Particle Tracks New... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2028Modeling D iscrete PhaseFigur e 24.41: The P article Tracks D ialo g Box The pr ocedur e for dr awing tr ajec tories f or par ticle injec tions is as f ollows: 1.Selec t the par ticle injec tion(s) y ou w ant to track in the Release fr om Injec tions list. (You c an cho ose t o track a sp ecific par ticle , inst ead, as descr ibed b elow.) 2.If you ha ve not done this y et, set the Step L ength F actor and the Max. Numb er of S teps (Track ing tab) in the Discrete Phase M odel D ialog Box (p.3360 ). Setup → Models → Discr ete Phase Edit... 2029Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Postpr ocessing f or the D iscrete PhaseIf stochastic and/or cloud tr acking is desir ed, set the r elated par amet ers in the Set Injec tion Properties dialo g box, as descr ibed in Stochastic Tracking (p.1978 ). Note Displa ying tr acks multiple times a t the same solution sta te will r esult in iden tical random tr acks .This is b ecause the same seeding is used enabling y ou t o postpr ocess different variables on the same par ticle tr acks . 3.(optional) S pecify which par ticles y ou w ant to displa y. a.If you w ant to displa y a single par ticle str eam, enable Track S ingle P article S tream and sp ecify the particle str eam ID numb er in the Stream ID field . Note •To det ermine the str eam ID in the injec tion of in terest, use the Injec tions D ialog Box (p.3837 ) to list the injec tion par ticle str eams , as descr ibed in Listing Injec tions (p.1968 ).The str eam ID numb ers will b e list ed in the first c olumn of the da ta pr inted in the ANSY S Fluen t con- sole . •For unst eady tracking, all of the par ticles r elated t o the sp ecified injec tion str eam will b e displa yed.The displa yed da ta will not c orrespond t o the time hist ory of an individual particle . b.(wall film mo del only) Enable Free S tream P articles and/or Wall F ilm P articles if you w ant to displa y those t ypes of par ticles . Note tha t these options ar e available only when the Lagr angian w all film model is enabled in the w all b oundar y conditions dialo g box, under the DPM tab . 4.Set an y of the displa y options descr ibed b elow. 5.Click the Displa y (or Save/D ispla y) butt on t o dr aw the tr ajec tories or click the Pulse butt on t o anima te the par ticle p ositions .The Pulse butt on will b ecome the Stop ! butt on dur ing the anima tion, and y ou must click Stop ! to stop the pulsing . Imp ortant •For unst eady par ticle tr acking simula tions , click ing Displa y will sho w only the cur rent location of the par ticles .Typic ally, you should selec t point in the Track S tyle drop-do wn list when displa ying tr ansien t par ticle lo cations sinc e individual p ositions will b e displa yed. •The Pulse butt on option is not a vailable f or unst eady tracking. 24.8.1.1. Options for P article Trajec tory Plots You c an include the mesh in the tr ajec tory displa y, control the st yle of the tr ajec tories (including the twisting of r ibbon-st yle tr ajec tories), color them b y diff erent scalar fields and c ontrol the c olor sc ale, and c oarsen tr ajec tory plots . (More inf ormation ab out these options c an b e found in Controlling the Particle Tracking S tyle (p.2031 ) and Controlling the Vector S tyle of P article Tracks (p.2033 ).) You c an also Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2030Modeling D iscrete Phasechoose no de or c ell v alues f or displa y. If you ar e “pulsing ” the tr ajec tories, you c an c ontrol the pulse mode. Finally , you c an gener ate an X Y plot of the par ticle tr ajec tory da ta (f or e xample , residenc e time) as a func tion of time or pa th length and sa ve this X Y plot da ta to a file . Note The Draw M esh option settings ar e not sa ved with the par ticle tr ack plot definition. Onc e the dialo g box is closed these settings will r evert to being disabled . If you w ant these settings p ersist ed within the cur rent session, you c an use the non-p ersist ent Particle Tracks dialo g box. Results → Graphics → Particle Tracks → Edit... Plotting par ticle tr ajec tories c an b e very time c onsuming , ther efore, to reduc e the plotting time , a coarsening fac tor c an b e used t o reduc e the numb er of p oints tha t are plott ed. Providing a c oarsening factor of , will r esult in each th point being plott ed f or a giv en tr ajec tory in an y cell.This c oarsening factor is sp ecified in the Particle Tracks D ialog Box (p.3881 ), in the Coarsen field and is only v alid f or steady-sta te cases . For e xample , if the c oarsening fac tor is set t o 2, then ANSY S Fluen t will plot alt ernate points. Imp ortant Note tha t if an y par ticle or pa thline en ters a new c ell, this p oint will alw ays be plott ed. To reduc e plotting time in tr ansien t cases , ANSY S Fluen t has a vailable an option t o sk ip plotting e very par ticle in an injec tion. Selec ting this option is also done in the Particle Tracks D ialog Box (p.3881 ) by sp ecifying a nonz ero in teger in the Skip field . For e xample , if an individual str eam is selec ted and the sk ip option is set t o 1, every other par ticle will b e plott ed. If the en tire injec tion is selec ted with a sk ip option of 1, every other par ticle will b e plott ed f or all str eams in the injec tion. These options ar e controlled in e xactly the same w ay tha t pa thline-plotting options ar e controlled . See Options f or P athline P lots (p.2804 ) for details ab out setting the tr ajec tory plotting options men tioned above. Note tha t in addition t o color ing the tr ajec tories b y continuous phase v ariables , you c an also c olor them acc ording t o the f ollowing discr ete phase v ariables: par ticle time , par ticle v elocity, par ticle dia- met er, par ticle densit y, par ticle mass , par ticle t emp erature, par ticle la w numb er, par ticle time st ep, and par ticle R eynolds numb er. If DEM C ollisions is enabled in the Discr ete Phase M odel dialo g box, you c an also selec t the magnitude or c omp onen ts of the c ollisional f orce ac ting on the DEM par cel, total f orce ac ting on the DEM par cel, and t otal acc eleration e xperienc ed b y the par ticles in the par cel. These v ariables ar e included in the Particle Variables ... categor y of the Color b y list. To displa y the minimum and maximum v alues in the domain, click the Update M in/M ax butt on. 24.8.1.2. Contr olling the P article Track ing St yle Particle tr acking c an b e displa yed as lines (with or without ar rows), ribbons, cylinders (c oarse , medium, or fine), triangles , spher es, or a set of p oints. In the Track S tyle drop-do wn list in the Particle Tracks dialo g box, you c an cho ose: •(steady tracking) line ,line-ar rows,point,spher e,ribbon,triangle ,coarse-c ylinder ,medium-c ylinder , or fine-c ylinder . 2031Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Postpr ocessing f or the D iscrete Phase•(unst eady tracking) point or spher e. Pulsing c an b e done only on point,spher e, or line styles . Onc e you ha ve selec ted the tr ack st yle, click the Attribut es... butt on t o sp ecify ho w you w ould lik e to displa y the par ticle tr acks . Note The Track S tyle options tha t will app ear dep end on whether y ou ar e running a tr an- sien t or st eady-sta te simula tion. For a tr ansien t case, the only Track S tyle options available ar e the point and spher e styles . •If you ar e using the line or line-ar rows style, set the Line Width in the Track S tyle A ttribut es dialo g box (Figur e 24.42: The Track S tyle A ttribut es D ialog Box (p.2032 )) tha t app ears when y ou click the Attribut es... butt on. For line-ar rows you will also set the Spacing F actor, which c ontrols the spacing b etween the particles tr acks .The siz e of the ar row heads c an b e adjust ed b y en tering a v alue in the Scale text-en try box. Figur e 24.42: The Track S tyle A ttribut es D ialo g Box •If you ar e using the point style, you will set the Marker S ize in the Track S tyle A ttribut es dialo g box. The thick ness of the par ticle tr ack will b e the thick ness of the mar ker. •If you ar e using the spher e style, you will set the Diamet er,scale, and Detail in the Particle S pher e Style Attribut es dialo g box (Figur e 24.43: The P article S pher e Style A ttribut es D ialog Box (p.2033 )).You ha ve the option of sp ecifying a c onstan t diamet er if y ou enable Constan t under Options and y ou will then sp ecify the Diamet er. If you enable Variable , you c an selec t a par ticle v ariable t o estima te the siz e of the spher es. The spher es ar e sc aled b y the fac tor en tered in the Scale entry box. The b est c onstan t diamet er to use will dep end on the dimensions of the domain, the view , and the par ticle densit y. However, an adequa te star ting p oint would b e a diamet er on the or der of 1/4 of the a verage c ell siz e or 1/4 st ep siz e. Units f or the Diamet er field c orrespond t o the mesh dimen- sional units . The le vel of detail applied t o the gr aphic al render ing of the spher es c an b e controlled using the Detail field .The le vel of detail uses in teger v alues r anging fr om 4 t o 50. Note tha t the p erformanc e of the gr aphic al render ing as w ell as the memor y consumption will b e better when using a small Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2032Modeling D iscrete Phaselevel of detail, tha t is, very coarse spher es, such as 6 or 8. The r ender ing p erformanc e signific antly decr eases with higher le vels of detail. You should gr adually incr ease the detail t o det ermine the best-c ase sc enar io b etween p erformanc e and qualit y. Whene ver Auto Range is disabled , the spher es ar e displa yed only if the y ha ve values b etween Min and Max. Also not e tha t to tak e full ad vantage of spher ical render ing, ligh ting should b e tur ned on in the view .The G ouraud setting pr ovides much smo other lo oking spher es than the F lat setting and better p erformanc e than the P hong setting . For mor e inf ormation on ligh ting , see Adding Ligh ts (p.2829 ). Figur e 24.43: The P article S pher e Style A ttribut es D ialo g Box •If you ar e using the triangle or an y of the cylinder styles , you will set the Width in the Track S tyle A ttrib- utes dialo g box. For tr iangles , the sp ecified v alue will b e half the width of the tr iangle ’s base , and f or c yl- inders , the v alue will b e the c ylinder ’s radius . •If you ar e using the ribbon style, click ing on the Attribut es... butt on will op en the Ribbon A ttribut es Dialog Box (p.3667 ), in which y ou c an set the r ibbon’s Width .You c an also sp ecify par amet ers f or twisting the r ibbon tr acks . In the Twist B y drop-do wn list , you c an selec t a sc alar field on which the tr acks t wisting is based (f or e xample , helicit y). Selec t the desir ed c ategor y in the upp er list and then selec t a r elated quan tity in the lo wer list. The t wisting ma y not b e displa yed smo othly b ecause the sc alar field b y which you ar e twisting the tr acks is c alcula ted a t cell c enters only (and not in terpolated t o a par ticle ’s position). The Twist Sc ale sets the amoun t of t wist f or the selec ted sc alar field .To magnify the t wist f or a field with very little change , incr ease this fac tor; to displa y less t wist f or a field with dr ama tic changes , decr ease this factor. When y ou click Comput e, the Min and Max fields will b e up dated t o sho w the r ange of the Twist By scalar field . 24.8.1.3. Contr olling the Vector St yle of P article Tracks You c an cho ose t o ha ve the par ticle tr acks displa yed as v ectors. Choose the Vector S tyle from the drop-do wn list in the Particle Tracks dialo g box: •If you selec t vector, the v ector will b e gener ated star ting in the c enter of the par ticle , as sho wn in Figur e 24.44: Particles with the Vector S tyle (p.2034 ). 2033Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Postpr ocessing f or the D iscrete Phase•If you selec t centered-v ector, the midp oint of the v ector will app ear in the c enter of the par ticle , as shown in Figur e 24.45: Particles with the C entered Vector S tyle (p.2035 ). •If you selec t centered-c ylinder , the midp oint of the c ylinder will app ear in the c enter of the par ticle , as sho wn in Figur e 24.46: Particles with the C entered C ylinder S tyle (p.2036 ). Figur e 24.44: Particles with the Vector S tyle Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2034Modeling D iscrete PhaseFigur e 24.45: Particles with the C entered Vector S tyle 2035Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Postpr ocessing f or the D iscrete PhaseFigur e 24.46: Particles with the C entered C ylinder S tyle Click the Attribut es... butt on t o sp ecify ho w you w ould lik e to displa y the par ticle tr acks . In the Particle Vector S tyle A ttribut es dialo g box (Figur e 24.47: The P article Vector S tyle A ttribut es D ialog Box (p.2037 )) you will set the Length ,Scale, and Length t o H ead R atio.The dir ection of the v ectors is displa yed f or the selec ted v ariable under Vectors of .You ha ve the option of sp ecifying a Constan t Length or a Variable L ength , which is based on the v ariable selec ted under Length b y. If Constan t Color is enabled , then all v ectors/c ylinders ar e color ed b y the c olor selec ted in the Color drop-do wn list. Other wise , it is the c olor selec ted in the Particle Tracks dialo g box (seen in the Mesh C olors dialo g box when Draw M esh is enabled). Vectors c an b e sc aled b y the fac tor giv en in the Scale entry box.The r atio of v ector length t o vector head siz e can b e changed in the b ox Length t o H ead R atio. In the c ase of a c ylinder , the r atio of the length t o the diamet er is aff ected. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2036Modeling D iscrete PhaseFigur e 24.47: The P article Vector S tyle A ttribut es D ialo g Box 24.8.1.4. Imp orting P article D ata Use the Imp ort Particle D ata dialo g box (Figur e 24.48: The Imp ort Particle D ata D ialog Box (p.2037 )) to imp ort par ticle da ta to displa y in the gr aphics windo w. Results → Model S pecific → Discr ete Phase → Imp ort Particle D ata... Figur e 24.48: The Imp ort Particle D ata D ialo g Box 1.Click Read ... to displa y a file selec tion dialo g box wher e you c an en ter a file name and a dir ectory tha t contains the imp orted da ta. 2.Choose fr om the a vailable imp ort options b y selec ting Auto Range and/or Draw M esh under Options . If you pr efer to restrict the r ange of the sc alar field , disable the Auto Range option and set the Min and Max values manually b enea th the Color b y list. 2037Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Postpr ocessing f or the D iscrete Phase3.Choose t o color the par ticle pa thlines b y an y of the sc alar fields in the Color b y list. If you selec t COLORBY , the pa thlines will b e color ed b y the quan tity tha t was chosen when the par ticle da ta file w as cr eated. (See Exporting S teady-State Particle Hist ory Data (p.625)) 4.Selec t a pa thline st yle under Style.To set pa thline st yle a ttribut es, click the Attribut es... butt on. For mor e inf ormation ab out the pa thline st yle t ypes, see Controlling the P athline S tyle (p.2805 ). 5.The v alue of Steps sets the maximum numb er of st eps a par ticle c an ad vance. A par ticle will st op when it has tr aveled this numb er of st eps or when it lea ves the domain. 6.If your pa thline plot is difficult t o understand b ecause ther e are too man y pa ths displa yed, you c an “thin out” the pa thlines b y changing the Skip value . 7.Click the Displa y butt on t o dr aw the pa thlines , or click the Pulse butt on t o anima te the par ticle p ositions . The Pulse butt on will b ecome the Stop ! butt on dur ing the anima tion, and y ou must click Stop ! to stop the pulsing . 24.8.1.5. Particle F iltering You c an sp ecify ho w you w ould lik e to filt er the par ticles b eing displa yed, by first enabling the Filter option, then click ing the Filter b y... butt on. In the Particle F ilter A ttribut es dialo g box, selec t the field v ariable b y which y ou w ant to filt er, then sp ecify whether y ou w ould lik e to displa y all the par ticle tracks Inside or Outside the Filter-M in and Filter-M ax range , as sho wn in Figur e 24.49: The P article Filter A ttribut es D ialog Box (p.2038 ). Note All par ticle v ariables as w ell as an y field v ariable e xcept f or Custom F ield F unc tions ... can be used as a filt er v ariable . Figur e 24.49: The P article F ilter A ttribut es D ialo g Box 24.8.1.6. Graphic al D ispla y for A xisymmetric G eometries For axisymmetr ic pr oblems in which the par ticle has a nonz ero cir cumf erential v elocity comp onen t, the tr ajec tory of an individual par ticle is of ten a spir al ab out the c enterline of r otation. ANSY S Fluen t Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2038Modeling D iscrete Phasedispla ys the and comp onen ts of the tr ajec tory (but not the comp onen t) pr ojec ted in the axisymmetr ic plane . 24.8.2. Rep orting of Trajec tory Fates When y ou p erform tr ajec tory calcula tions b y displa ying the tr ajec tories (as descr ibed in Displa ying of Trajec tories (p.2028 )), ANSY S Fluen t will pr ovide inf ormation ab out the tr ajec tories as the y are complet ed. By default , the numb er of tr ajec tories with each p ossible fa te (esc aped, aborted, evaporated, and so on) is r eported: DPM Iteration .... num. tracked = 7, escaped = 4, aborted = 0, trapped = 0, evaporated = 3, inco Done. You c an also tr ack par ticles thr ough the domain without displa ying the tr ajec tories b y click ing the Track butt on a t the b ottom of the dialo g box.This allo ws the listing of r eports without also displa ying the tr acks . 24.8.2.1. Trajec tory Fates The p ossible fa tes for a par ticle tr ajec tory are as f ollows: •“Escaped” trajec tories ar e those tha t termina te at a flo w boundar y for which the “escape” condition is set. •“Inc omplet e” trajec tories ar e those tha t were termina ted when the maximum allo wed numb er of time steps — as defined b y the Max. Numb er of S teps input in the Discrete Phase M odel D ialog Box (p.3360 ) (see Numer ics of the D iscrete Phase M odel (p.1937 )) — w as e xceeded . •“Inc omplet e_par allel ” may app ear as an additional fa te for par allel simula tions .This means tha t the numb er of par ticle e xchanges b etween par titions has b een e xceeded . Any remaining par ticles on the comput e no des ar e stopp ed, which is indic ated b y the numb er following this fa te.Therefore no fur ther sour ce terms fr om these par ticles ar e consider ed.The numb er of par ticle e xchanges is limit ed t o avoid very long c omputa tional time due t o inc omplet e par ticles .You c an change the default v alue of 1000 t o a value of 20000 with a scheme c ommand . Contact the t echnic al supp ort engineer f or this inf ormation. •“Trapp ed” trajec tories ar e those tha t termina te at a flo w boundar y wher e the “trap” condition has b een set. •“Evaporated” trajec tories include those tr ajec tories along which the par ticles w ere evaporated within the domain. •“Aborted” trajec tories ar e those tha t fail t o complet e due t o roundoff r easons .You ma y want to retry the calcula tion with a mo dified length sc ale and/or diff erent initial c onditions . •“Shed ” trajec tories ar e newly gener ated par ticles dur ing the br eakup of a lar ger dr oplet. They app ear only if a br eakup mo del is enabled . •“Coalesc ed” trajec tories ar e remo ved par ticles which ha ve coalesc ed af ter par ticle-par ticle c ollisions .They app ear only if the c oalesc ence mo del is enabled . •“Splashed ” trajec tories ar e par ticles tha t are newly gener ated when a par ticle t ouches a w all film. Those trajec tories app ear only if the w all film mo del is enabled . 2039Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Postpr ocessing f or the D iscrete Phase24.8.2.2. Summar y Reports You c an r equest additional detail ab out the tr ajec tory fates as the par ticles e xit the domain, including the mass flo w rates thr ough each b oundar y zone , mass flo w rate of e vaporated dr oplets , and c om- position of the par ticles . 1.Follow st eps 1 and 2 in Displa ying of Trajec tories (p.2028 ) for displa ying tr ajec tories. 2.Selec t Summar y as the Rep ort Type and click Displa y or Track. Imp ortant For st eady-sta te simula tions , DPM summar y da ta is not st ored in the .dat file, sinc e it is p ossible t o track par ticles on single or c ombina tions of injec tions .Transien t simu- lations st ore this da ta sinc e it is accumula ted o ver time star ting fr om initializa tion. A detailed r eport similar t o the f ollowing e xample will app ear in the c onsole windo w. (You ma y also choose t o wr ite this r eport to a file b y selec ting File as the Rep ort to option, click ing the Write... butt on (which w as or iginally the Displa y butt on), and sp ecifying a file name f or the summar y report file in The S elec t File D ialog Box (p.569).) number tracked = 10, escaped = 3, aborted = 0, trapped = 5, evaporated = 2, Fate Number Elapsed Time (s) Min Max Avg Std Dev ---- ------ ---------- ---------- ---------- ---------- Evaporated 2 1.770e-003 1.114e-002 6.456e-003 4.686e-003 Escaped - Zone 6 3 6.043e-001 7.037e-001 6.471e-001 4.172e-002 Trapped - Zone 7 5 8.486e-003 1.767e-001 5.030e-002 6.421e-002 (*)- Mass Transfer Summary -(*) Fate Mass Flow (kg/s) Initial Final Change ---- ---------- ---------- ---------- Evaporated 8.333e-002 0.000e+000 -8.333e-002 Escaped - Zone 6 1.167e-001 5.144e-002 -6.523e-002 Trapped - Zone 7 2.000e-001 2.400e-002 -1.760e-001 ---- ---------- ---------- ---------- Net 4.000e-001 7.544e-002 -3.246e-001 (*)- Energy Transfer Summary -(*) Fate Heat Rate (W) Change of Heat (W) Initial Final Sensible Latent React ---- ---------- ---------- ---------- ---------- ------- Evaporated -3.180e+004 0.000e+000 -3.382e+002 3.214e+004 1.107 Escaped - Zone 6 5.272e+005 6.519e+005 -3.487e+003 1.282e+005 1.523 Trapped - Zone 7 4.954e+005 6.993e+005 -1.173e+003 2.051e+005 1.737 ---- ---------- ---------- ---------- ---------- ------ Net 9.908e+005 1.351e+006 -4.998e+003 3.654e+005 4.367 (*)- Combusting Particles -(*) Fate Volatile Content (kg/s) Char Content (kg/s) Initial Final %Conv Initial Final ---- ---------- ---------- ------- ---------- ---------- Evaporated 0.000e+000 0.000e+000 0.00 0.000e+000 0.000e+000 Escaped - Zone 6 9.333e-003 9.333e-003 0.00 2.133e-002 2.133e-002 Trapped - Zone 7 9.333e-003 7.485e-010 100.00 2.133e-002 2.133e-002 ---- ---------- ---------- ------- ---------- ---------- Net 1.867e-002 9.333e-003 50.00 4.267e-002 4.267e-002 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2040Modeling D iscrete Phase (*) - Multicomponent Droplet -(*) Fate Species Species Content (kg/s) Names Initial Final %Conv ---- ------- ---------- ---------- ------- Evaporated c5h12-droplet 1.667e-002 0.000e+000 100.00 Evaporated c7h16-droplet 3.333e-002 0.000e+000 100.00 Evaporated h2o 0.000e+000 0.000e+000 0.00 Escaped - Zone 6 c5h12-droplet 1.667e-002 2.585e-004 98.45 Escaped - Zone 6 c7h16-droplet 0.000e+000 0.000e+000 0.00 Escaped - Zone 6 h2o 3.333e-002 1.134e-002 65.99 Trapped - Zone 7 c5h12-droplet 3.333e-002 0.000e+000 100.00 Trapped - Zone 7 c7h16-droplet 3.333e-002 0.000e+000 100.00 Trapped - Zone 7 h2o 3.333e-002 0.000e+000 100.00 The r eport groups t ogether par ticles with each p ossible fa te, and r eports the numb er of par ticles , the time elapsed dur ing tr ajec tories, and the mass and ener gy transf er This inf ormation c an b e very useful f or obtaining inf ormation such as wher e par ticles ar e esc aping fr om the domain, wher e par ticles are colliding with sur faces, and the e xtent of hea t and mass tr ansf er to/from the par ticles within the domain. Additional inf ormation is r eported f or c ombusting par ticles and multic omp onen t par ticles . 24.8.2.2.1. Elapsed Time The numb er of par ticles with each fa te is list ed under the Number heading . (Particles tha t esc ape through diff erent zones or ar e trapp ed a t diff erent zones ar e consider ed t o ha ve diff erent fates, and are ther efore list ed separ ately.) The minimum, maximum, and a verage time elapsed dur ing the tr a- jectories of these par ticles , as w ell as the standar d de viation ab out the a verage time , are list ed in the Min ,Max ,Avg , and Std Dev columns .This inf ormation indic ates ho w much time the par ticle(s) spent in the domain b efore the y esc aped, aborted, evaporated, or w ere trapp ed. Fate Number Elapsed Time (s) Min Max Avg Std Dev ---- ------ ---------- ---------- ---------- ---------- --- Incomplete 2 1.485e+01 2.410e+01 1.947e+01 4.623e+00 Escaped - Zone 7 8 4.940e+00 2.196e+01 1.226e+01 4.871e+00 Also, on the r ight side of the r eport are list ed the injec tion name and inde x of the tr ajec tories with the minimum and maximum elapsed times . (You ma y need t o use the scr oll bar t o view this inf orm- ation.) Elapsed Time (s) Injection, Index Min Max Avg Std Dev Min Max --- ---------- ---------- ---------- -------------------- ------------------ +01 2.410e+01 1.947e+01 4.623e+00 injection-0 1 injection-0 0 +00 2.196e+01 1.226e+01 4.871e+00 injection-0 9 injection-0 2 24.8.2.2.2. Mass Transfer S ummar y For all dr oplet or c ombusting par ticles with each fa te, the t otal initial and final mass flo w rates and the change in mass flo w rate ar e reported in the Initial ,Final , and Change columns .With this information, you c an det ermine ho w much mass w as tr ansf erred t o the c ontinuous phase fr om the particles . For unst eady tracking, the r eport lists the time-in tegrated mass flo w rate of the par ticle str eams tha t have reached a par ticular fa te at the cur rent flo w time . In other w ords, the r eport do es not include particles tha t are still b eing tr acked in the domain. (*)- Mass Transfer Summary -(*) Fate Mass Flow (kg/s) 2041Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Postpr ocessing f or the D iscrete Phase Initial Final Change ---- ---------- ---------- ---------- Incomplete 1.388e-03 1.943e-04 1.194e-03 Escaped - Zone 7 1.502e-03 2.481e-04 -1.254e-03 24.8.2.2.3. Ener gy Transfer S ummar y This r eport tells y ou ho w much hea t was tr ansf erred fr om the par ticles t o the c ontinuous phase .The report is or ganiz ed in t wo sec tions . For st eady simula tions , ther e is a Heat Rate and a Change of Heat sec tion. For unst eady par ticle tr acking, ther e is an Energy and a Change of Energy section. The Heat Rate and Energy sec tions ar e the same f or all par ticle t ypes, while the other sections r eport the change of hea t due t o the v arious tr ansf er pr ocesses , which diff er for each par ticle type. For st eady simula tions , the r eport lists the r ate and the change of hea t for the par ticle str eams organiz ed acc ording t o the par ticle str eam fa tes. For unst eady tracking, the r eport lists the time in- tegrated hea t rate and change of the par ticle str eams tha t ha ve reached a par ticular fa te at the current flo w time . Note tha t the r eport do es not include par ticles tha t are still b eing tr acked in the domain. 24.8.2.2.4. Heat R ate and E ner gy Reporting For all par ticles with each fa te, the t otal initial and final hea t content are reported in the Initial and Final columns .The par ticle hea t content is defined as f ollows: Iner t Particles: (24.15) wher e: = mass flo w rate of par ticles (k g/s) = temp erature of par ticles (K) = hea t capacit y of par ticles ( J/kg/K) = reference temp erature for en thalp y (K) Droplet P articles: (24.16) wher e: = hea t of p yrolysis ( J/kg) = la tent hea t of e vaporation a t reference conditions ( J/kg) The la tent hea t at the r eference conditions is defined in Equa tion 16.470 in the Theor y Guide . Combusting P articles: (24.17) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2042Modeling D iscrete Phase is the hea t content of the e vaporating/b oiling liquid ma terial if Wet C ombustion is selec ted (other wise = 0). (24.18) wher e: is the mass fr action of the liquid in the c ombusting par ticle , , and are pr operties of the e vaporating liquid ma terial is the hea t content of the dr y combusting par ticle and is c alcula ted as (24.19) wher e: is the v olatile fr action is the c ombustible fr action Imp ortant The Heat Rate sec tion of the r eport is not pr ovided f or the multiple sur face reactions model. Multic omp onen t Particles: (24.20) wher e: = mass fr action of c omp onen t i in par ticle = hea t content of c omp onen t i and (24.21) wher e: = hea t of p yrolysis f or c omp onen t i (J/kg) = la tent hea t of e vaporation a t reference conditions f or c omp onen t i (J/kg) = sp ecific hea t of c omp onen t i (J/kg/K) 2043Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Postpr ocessing f or the D iscrete Phase24.8.2.2.4.1. Change of H eat and C hange of E ner gy Reporting This sec tion r eports the t otal hea t transf erred fr om the par ticle t o the c ontinuous phase and is ana- lyzed in c omp onen ts of Sensible hea t,Latent hea t and hea t of Reaction .The Total change reported equals the diff erence between the Initial and Final states of the par ticle str eams . The sensible hea t comp onen t is r eported f or all par ticle t ypes, the la tent hea t for the dr oplet , com- busting and multic omp onen t par ticle , while the hea t of r eaction is r eported f or the c ombusting particle t ype only . A p ositiv e Change of Heat denot es tha t hea t is e xpelled fr om the c ontinuous phase and absorb ed b y the par ticle , while a nega tive Change of Heat denot es hea t is r eleased by the par ticle t o the c ontinuous phase . Stead y and Transien t Simula tions For st eady simula tions the r eport lists the hea t rate , while f or unst eady tracking the time in tegrated ener gy from time 0 t o cur rent flo w time is reported. (24.22) Below is an e xample of an Energy Transfer Summary report for e vaporating dr oplets: (*)- Energy Transfer Summary -(*) Fate Heat Rate (W) Change of Heat (W) Initial Final Sensible Latent Total ---- ---------- ---------- ---------- ---------- ---------- Evaporated -4.530e+004 0.000e+000 -4.750e+002 4.577e+004 4.530e+004 Escaped-Zone 6 -1.723e+005 -4.670e+004 -2.552e+003 1.282e+005 1.256e+005 Trapped-Zone 7 -2.176e+005 0.000e+000 -1.058e+003 2.187e+005 2.176e+005 ---- ---------- ---------- ---------- ---------- ---------- Net -4.353e+005 -4.670e+004 -4.085e+003 3.927e+005 3.886e+005 Below is an e xample of an Energy Transfer Summary report for c ombusting par ticles: (*)- Energy Transfer Summary -(*) Fate Heat Rate (W) Change of Heat (W) Initial Final Sensible Latent Reaction Tot ---- ---------- ---------- ---------- ---------- ---------- ------ Escaped-Zone 5 1.697e+005 2.555e+004 3.166e+003 1.034e+000 -1.473e+005 -1.44 Trapped-Zone 6 1.886e+004 1.938e+004 5.731e+002 1.149e-001 -5.370e+001 5.19 ---- ---------- ---------- ---------- ---------- ---------- ------ Net 1.886e+005 4.493e+004 3.739e+003 1.149e+000 -1.474e+005 -1.43 Imp ortant In a c oupled c alcula tion, for all t ypes of st eady flo ws, the Total Net Change of Heat reported in the Energy Transfer Summary should balanc e with the opp osite of the Sum over all fluid c ells of the DPM Sensible Enthalpy Source . If this is not the c ase, this means tha t the c oupled discr ete-continuous phase c alcula tion has not converged , and mor e DPM phase it erations ar e requir ed. For mor e inf ormation on c oupled calcula tions , see Performing Trajec tory Calcula tions (p.2022 ). Sum DPM Sensible Enthalpy Source (w) -------------------------------- -------------------- fluid-1 -388937.41 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2044Modeling D iscrete Phase24.8.2.2.5. Combusting P articles If combusting par ticles ar e pr esen t, ANSY S Fluen t will include additional r eporting on the v olatiles and char c onverted.These r eports ar e in tended t o help y ou iden tify the c omp osition of the c ombust- ing par ticles as the y exit the c omputa tional domain. (*)- Combusting Particles -(*) Fate Volatile Content (kg/s) Char Content (kg/s) Initial Final %Conv Initial Final %Conv ---- ---------- ---------- ------- ---------- --------- ------- Incomplete 6.247e-04 0.000e+00 100.00 5.691e-04 0.000e+00 100.00 Escaped - Zone 7 6.758e-04 0.000e+00 100.00 6.158e-04 3.782e-05 93.86 The t otal v olatile c ontent at the star t and end of the tr ajec tory is r eported in the Initial and Final columns under Volatile Content .The p ercentage of v olatiles tha t has b een de volatilized is reported in the %Conv column. The t otal r eactive portion (char) a t the star t and end of the tr ajec tory is r eported in the Initial and Final columns under Char Content .The p ercentage of char tha t reacted is r eported in the %Conv column. 24.8.2.2.6. Combusting P articles with the Multiple S urface Reac tion Mo del If the multiple sur face reaction mo del is used with c ombusting par ticles , ANSY S Fluen t will include additional r eporting on the mass of the individual solid sp ecies tha t constitut e the par ticle mass . (*)- Multiple Surface Reactions -(*) Fate Species Species Content (kg/s) Names Initial Final %Conv ---- ------- ---------- ---------- ------- Escaped - Zone 6 c 6.080e-02 1.487e-06 100.00 Escaped - Zone 6 s 3.200e-03 5.077e-06 99.84 Escaped - Zone 6 cao 0.000e+00 1.153e-03 0.00 Escaped - Zone 6 caso4 0.000e+00 9.266e-04 0.00 Escaped - Zone 6 caco3 8.000e-03 5.260e-03 34.25 The t otal mass of each solid sp ecies in the par ticles a t the star t and end of the tr ajec tory is r eported in the Initial and Final columns , respectively.The p ercentage of each sp ecies tha t is r eacted is reported in the %Conv column. Note tha t for the solid r eaction pr oduc ts (f or e xample , if the mass of a solid sp ecies has incr eased in the par ticle), the c onversion is r eported t o be 0. 24.8.2.2.7. Multic omp onent P articles If your simula tion includes multic omp onen t par ticles , ANSY S Fluen t gener ates an additional r eport for the par ticle c omp onen ts. (*) - Multicomponent Droplet -(*) Fate Species Species Content (kg/s) Names Initial Final %Conv ---- ------- ---------- ---------- ------- Evaporated c5h12-droplet 1.667e-002 0.000e+000 100.00 Evaporated c7h16-droplet 3.333e-002 0.000e+000 100.00 Evaporated h2o 0.000e+000 0.000e+000 0.00 Escaped - Zone 6 c5h12-droplet 1.667e-002 2.585e-004 98.45 Escaped - Zone 6 c7h16-droplet 0.000e+000 0.000e+000 0.00 Escaped - Zone 6 h2o 3.333e-002 1.134e-002 65.99 Trapped - Zone 7 c5h12-droplet 3.333e-002 0.000e+000 100.00 Trapped - Zone 7 c7h16-droplet 3.333e-002 0.000e+000 100.00 Trapped - Zone 7 h2o 3.333e-002 0.000e+000 100.00 2045Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Postpr ocessing f or the D iscrete Phase24.8.3. Step-b y-Step Rep orting of Trajec tories At times , you ma y want to obtain a detailed , step-b y-step r eport of the par ticle tr ajec tory/trajec tories. Such r eports can b e obtained in alphanumer ic format.This c apabilit y allo ws you t o monit or the par ticle position, velocity, temp erature, or diamet er as the tr ajec tory pr oceeds . The pr ocedur e for gener ating files c ontaining st ep-b y-step r eports is list ed b elow: 1.Follow st eps 1 and 2 in Displa ying of Trajec tories (p.2028 ) for displa ying tr ajec tories.You ma y want to track only one par ticle str eam a t a time , using the Track S ingle P article S tream option. 2.Selec t Step b y Step as the Rep ort Type. Imp ortant This option is only a vailable f or st eady-sta te cases . For tr ansien t cases , see Reporting of Current Positions f or U nsteady Tracking (p.2048 ). 3.Selec t File as the Rep ort to option. (The Track butt on will b ecome the Write... butt on.) 4.In the Signific ant Figur es field , enter the numb er of signific ant figur es to be used in the st ep-b y-step report. 5.Click the Rep orting Variables ... butt on. 6.Figur e 24.50: The Rep orting Variables D ialo g Box 7.In the Rep orting Variables dialo g box (Figur e 24.50: The R eporting Variables D ialog Box (p.2046 )), you c an change the v ariables in the r eport.The list under Variables in Rep ort contains all v ariables cur rently r e- ported.The list under Particle Variables contains the par ticle v ariables tha t are available f or y ou t o selec t. You c an use the f ollowing butt ons t o mo dify the Variables in Rep ort list: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2046Modeling D iscrete Phase•Remo ve: Remo ves selec ted v ariables fr om tha t list. •Default Variables : Restores the default list. •Add Variable : Adds selec tions t o the r eport using . •Add C olor b y: Adds the Color b y variable t o the list of Variables in Rep ort, which is the only w ay to get c ell v alues or cust omiz ed field func tions in to the r eport. Imp ortant Note tha t it is p ossible t o selec t one v ariable in the Rep orting Variables dialo g box and a v ariable fr om the Color b y drop-do wn list in the Particle Tracks dialo g box, however, each v ariable is r eported only onc e. 8.Click the Write... butt on and sp ecify a file name f or the st ep-b y-step r eport file in The S elec t File D ialog Box (p.569). A detailed r eport similar t o the f ollowing e xample will b e sa ved t o the sp ecified file b efore the tr ajec t- ories ar e plott ed. (You ma y also cho ose t o pr int the r eport in the c onsole b y cho osing Console as the Rep ort to option and click ing Displa y or Track, but the r eport is v ery long tha t it is unlik ely t o be of use t o you in tha t form.) FILE TYPE: 1 COLUMNS: 11 TITLE: TRACK HISTORY COLUMN TYPE VARIABLE (UNITS) ------ ---- -------- ------- 1 2 ParticleResidenceTime (s) 2 10 ParticleXPosition (m) 3 10 ParticleYPosition (m) 4 10 ParticleZPosition (m) 5 10 ParticleXVelocity (m/s) 6 10 ParticleYVelocity (m/s) 7 10 ParticleZVelocity (m/s) 8 10 ParticleDiameter (m) 9 10 ParticleTemperature (K) 10 10 ParticleDensity (kg/m3) 11 10 ParticleMass (kg) --------------------------------------------- 0.00000e+00 5.00000e-02 5.00000e-02 5.00000e-02 2.00000e+01 0.0000 . . . 1.07087e-07 5.00000e-02 5.00000e-02 5.00000e-02 1.23339e+01 2.6696 . . . 2.51617e-07 5.00000e-02 5.00000e-02 5.00000e-02 1.04417e+01 3.3286 . . . . . . . . . . . . . . . . . . . . . The default st ep-b y-step r eport lists the p osition, velocity, diamet er, temp erature, densit y and mass of the par ticle a t selec ted time st eps along the tr ajec tory. In addition, the v ariable y ou ha ve selec ted in the Color b y list is also included . If you cho ose Console as the Rep ort to option, the v ariable names are wr itten as the header of each c olumn. (You ma y need t o use the scr oll bar t o view all v ariables in this c olumn.) Time X-Position Y-Position Z-Position X-Velocity Y-Velocity Z-Veloc 0.000e+00 1.000e-03 3.120e-02 0.000e+00 1.000e+01 5.000e+00 0.000e 1.672e-05 1.168e-03 3.128e-02 0.000e+00 1.010e+01 4.988e+00 0.000e 3.342e-05 1.337e-03 3.137e-02 0.000e+00 1.019e+01 4.977e+00 0.000e 5.010e-05 1.508e-03 3.145e-02 0.000e+00 1.028e+01 4.965e+00 0.000e 2047Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Postpr ocessing f or the D iscrete Phase6.675e-05 1.680e-03 3.153e-02 0.000e+00 1.038e+01 4.954e+00 0.000e 8.338e-05 1.854e-03 3.161e-02 0.000e+00 1.047e+01 4.942e+00 0.000e . . . . . . . . . . . . . . . . . . . . . If you change the r eporting v ariables , only those selec ted will app ear in the r eport.The par ticle time is alw ays reported in the first c olumn. Note tha t it is p ossible t o selec t one v ariable in the Rep orting Variables dialo g box and a v ariable fr om the Color b y drop-do wn list in the Particle Tracks dialo g box, however, each v ariable is r eported only onc e. When the r eport is wr itten t o a file , a table a t the b eginning of the file lists all v ariables selec ted with the c orresponding unit. Thus y ou c an displa y or e xport an y variable along a par ticle tr ajec tory to the console or t o a file . Note tha t the Coarsen option aff ects the st ep-b y-step r eport. 24.8.4. Rep orting of C urrent Positions f or U nstead y Track ing In tr ansien t cases , when using unst eady tracking, you ma y want to obtain a r eport of the par ticle tr a- jectory/trajec tories sho wing the cur rent positions of the par ticles . Selec ting Current Positions under Rep ort Type in the Particle Tracks D ialog Box (p.3881 ) enables the displa y of the cur rent positions of the par ticles . The pr ocedur e for gener ating files c ontaining cur rent position r eports is list ed b elow: 1.Follow st eps 1 and 2 in Displa ying of Trajec tories (p.2028 ) for displa ying tr ajec tories.You ma y want to track only one par ticle str eam a t a time , using the Track S ingle P article S tream option. 2.Selec t Current Position as the Rep ort Type. 3.Selec t File as the Rep ort to option. (The Track butt on will b ecome the Write... butt on.) 4.In the Signific ant Figur es field , enter the numb er of signific ant figur es to be used in the r eport. 5.Click the Rep orting Variables ... butt on. 6.In the Rep orting Variables dialo g box (Figur e 24.50: The R eporting Variables D ialog Box (p.2046 )), you c an change the v ariables in the r eport.The list under Variables in Rep ort contains all v ariables cur rently r e- ported.The list under Particle Variables contains the par ticle v ariables tha t are available f or y ou t o selec t. You c an use the f ollowing butt ons t o mo dify the Variables in Rep ort list: •Remo ve: Remo ves selec ted v ariables fr om tha t list. •Default Variables : Restores the default list. •Add Variable : Adds selec tions t o the r eport. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2048Modeling D iscrete Phase•Add C olor b y: Adds the Color b y variable t o the list of Variables in Rep ort, which is the only w ay to get c ell v alues or cust omiz ed field func tions in to the r eport. Imp ortant Note tha t it is p ossible t o selec t one v ariable in the Rep orting Variables dialo g box and a v ariable fr om the Color b y drop-do wn list in the Particle Tracks dialo g box, however, each v ariable is r eported only onc e. 7.Click the Write... butt on and sp ecify a file name f or the cur rent position r eport file in The S elec t File D ialog Box (p.569). The default cur rent position r eport lists the p osition, velocity, diamet er, temp erature, densit y, mass and numb er in par cel of the par ticle a t selec ted time st eps along the tr ajec tory. In addition, the v ariable you ha ve selec ted in the Color b y list is also included . If you change the r eporting v ariables , only those selec ted will app ear in the r eport.The par ticle time is alw ays reported in the first c olumn. It is p ossible to selec t one v ariable in the Rep orting Variables dialo g box and a v ariable fr om the Color b y drop- down list in the Particle Tracks dialo g box, however, each v ariable is r eported only onc e. The output t o a file or t o the c onsole has the same f ormat as the st ep-b y-step r eport for st eady-sta te cases . Time X-Position Y-Position Z-Position X-Velocity Y-Velocity Z-Velocity 0.000e+00 1.000e-03 3.120e-02 0.000e+00 1.000e+01 5.000e+00 0.000e+00 1.672e-05 1.168e-03 3.128e-02 0.000e+00 1.010e+01 4.988e+00 0.000e+00 3.342e-05 1.337e-03 3.137e-02 0.000e+00 1.019e+01 4.977e+00 0.000e+00 5.010e-05 1.508e-03 3.145e-02 0.000e+00 1.028e+01 4.965e+00 0.000e+00 6.675e-05 1.680e-03 3.153e-02 0.000e+00 1.038e+01 4.954e+00 0.000e+00 8.338e-05 1.854e-03 3.161e-02 0.000e+00 1.047e+01 4.942e+00 0.000e+00 . . . . . . . . . . . . . . . . . . . . . Also list ed ar e the diamet er, temp erature, densit y, mass of the par ticles , numb er in par cel and the variable selec ted fr om the Color b y list. (You ma y need t o use the scr oll bar t o view this inf ormation.) Time Diameter Temperature Density Mass Number ColorBy 9.999e-04 9.352e-05 3.710e+02 6.840e+02 2.929e-10 2.792e+02 4.783e-02 1.999e-03 7.952e-05 3.710e+02 6.840e+02 1.801e-10 2.792e+02 3.834e-02 3.000e-03 6.660e-05 3.710e+02 6.840e+02 1.058e-10 2.792e+02 2.989e-02 4.001e-03 5.425e-05 3.710e+02 6.840e+02 5.719e-11 2.792e+02 3.719e-02 5.001e-03 4.184e-05 3.710e+02 6.840e+02 2.624e-11 2.792e+02 2.978e-02 . . . . . . . . . . . . . . . . . . . . . 24.8.5. Rep orting of In terphase E xchange Terms (D iscr ete Phase S our ces) ANSY S Fluen t reports the magnitudes of the in terphase e xchange of momen tum, hea t, and mass in each c ontrol volume in y our ANSY S Fluen t mo del. You c an displa y these v ariables gr aphic ally, by drawing c ontours , profiles , and so on. They are all c ontained in the Discr ete Phase S our ces... categor y of the v ariable selec tion dr op-do wn list tha t app ears in p ostpr ocessing dialo g boxes: •DPM M ass S our ce •DPM X,Y ,Z M omen tum S our ce 2049Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Postpr ocessing f or the D iscrete Phase•DPM S wirl Momen tum S our ce •DPM Turbulen t Kinetic E nergy Sour ce •DPM Turbulen t Dissipa tion S our ce •DPM S ensible E nthalp y Sour ce •DPM E nthalp y Sour ce •DPM Bur nout •DPM E vaporation/D evolatiliza tion •DPM (sp ecies) S our ce See Field F unction D efinitions (p.2959 ) for definitions of these v ariables . Note tha t these e xchange t erms ar e up dated and displa yed only when c oupled c alcula tions ar e per- formed . Displa ying and r eporting par ticle tr ajec tories (as descr ibed in Displa ying of Trajec tories (p.2028 ) and Reporting of Trajec tory Fates (p.2039 )) will not aff ect the v alues of these e xchange t erms. The e xchange t erms ar e reported as the r ate occur ring in each c ell. A unit c ell depth is used f or 2D cases , and a r eference cell depth of 1 r adian is used f or 2D axisymmetr ic cases . 24.8.6. Rep orting of D iscr ete Phase Variables ANSY S Fluen t reports various discr ete phase par ticle/par cel quan tities including er osion/accr etion r ates, radia tion quan tities , and (optionally) c ell-a veraged par ticle siz e, velocity, temp erature, and so on. You can displa y these v ariables gr aphic ally, by dr awing c ontours , profiles , and so on. They are acc essed in the Discr ete Phase Variables ... categor y of the v ariable selec tion dr op-do wn list tha t app ears in postpr ocessing dialo g boxes. Several quan tities ar e aut oma tically a vailable dep ending on the mo dels b eing used in the simula tion. For the c ell-a veraged quan tities t o be available , you must first enable Mean Values under Contour Plots f or DPM Variables in the Discr ete Phase M odel dialo g box,Discrete Phase M odel D ialog Box (p.3360 ). RMS quan tities ar e also a vailable f or par ticle v elocity and t emp erature by enabling RMS Values . Note Enabling M ean Values t o track the c ell-a veraged v ariables will incr ease the memor y requir emen ts of y our simula tion. The f ollowing lists sp ecify those v ariables tha t are available aut oma tically and those tha t requir e you to enable them Variables a vailable aut omatic ally •DPM E rosion R ate (G ener ic) •DPM E rosion R ate (F innie) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2050Modeling D iscrete Phase•DPM E rosion R ate (M cLaur y) •DPM E rosion R ate (O ka) •DPM E rosion R ate (Wall S hear) •DPM A ccretion R ate •DPM A bsor ption C oefficien t •DPM E mission •DPM Sc attering •DPM C onc entration •DPM Wall X F orce •DPM Wall Y Force •DPM Wall Z F orce •DPM Wall N ormal P ressur e •DPM (sp ecies) C onc entration •DPM C ollision R ate Particle r otation v ariables (P article r otation simulations onl y) •Angular X Velocity •Angular Y Velocity •Angular Z Velocity •Angular Velocity M agnitude •Angular Velocity (in the Particle Vector S tyle dialo g box) Cell-a veraged v ariables a vailable when Mean Values are enabled •DPM Volume F raction •DPM P articles in C ell •DPM P arcels in C ell •DPM N umb er D ensit y •DPM X, Y, Z Velocity •DPM D iamet er •DPM D ensit y 2051Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Postpr ocessing f or the D iscrete Phase•DPM Temp erature •DPM S pecific H eat •DPM D20 •DPM D30 •DPM D32 •DPM D43 •DPM G ranular Temp erature •DPM C onc . of (c omp onen t) RMS v ariables a vailable when Mean Values and RMS Values are enabled •DPM RMS X, Y, Z Velocity •DPM RMS Temp erature •DPM RMS D iamet er See Field F unction D efinitions (p.2959 ) for definitions of these v ariables . Note tha t these v ariables ar e up dated and displa yed only when c oupled c alcula tions ar e performed . Displa ying and r eporting par ticle tr ajec tories (as descr ibed in Displa ying of Trajec tories (p.2028 ) and Reporting of Trajec tory Fates (p.2039 )) will not aff ect the v alues of these v ariables . Note If you selec t Enable N ode B ased A veraging in the Numer ics tab of the Discr ete Phase Model dialo g box, any pr eviously c alcula ted DPM v ariables will b e render ed useless and need t o be recomput ed. 24.8.6.1. Note on the C ell-A veraging of P article Variables DPM par ticles ar e ac tually numer ical par cels, each of which c an r epresen t an arbitr ary numb er of physical par ticles .Therefore, a par cel represen ting man y ph ysical par ticles c ontribut es mor e to the averaging in a c ell it cr osses than a par cel represen ting f ewer ph ysical par ticles . Likewise , a par cel tha t sp ends mor e time in a c ell c ontribut es mor e to the a veraging in tha t cell than a par cel tha t lea ves the c ell v ery so on af ter en tering it (f or e xample , when it passes only thr ough a corner of the c ell, very close t o the no de). These imp ortant asp ects of w eigh ting ar e acc oun ted f or in the c alcula tion of the DPM v ariables tha t are available as p ostpr ocessing c ell-wise field v ariables in ANSY S Fluen t. 24.8.7. Rep orting of U nstead y DPM S tatistics If you ar e performing a tr ansien t simula tion, you c an include the c omputa tion of unst eady time sta t- istics (mean and RMS) f or the discr ete phase(s) of the tr ansien t flo w.These ar e comput ed on a p er- Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2052Modeling D iscrete Phasephase basis b y event-based time a veraging o ver the discr ete phase par cels in the domain. This means that the sampling of the discr ete phase par ticle quan tity in a giv en c ell o ccurs when (and only when) a par cel passes thr ough the c ell. To calcula te the unst eady DPM time sta tistics , enable Data S ampling f or Time S tatistics in the Run Calcula tion task page and enable DPM Variables in the Sampling Options dialo g box when pr epar ing to run y our simula tion (see User Inputs f or Time-D ependen t Problems (p.2627 )). For a discr ete phase v ariable , , the e vent-based time a verage (mean) in a c ell is c alcula ted fr om Equa tion 24.23 (p.2053 ). (24.23) wher e is the numb er of par cels in the domain, and (24.24) Here is the numb er of par ticles in the th par cel and is the r esidenc e time of the th par cel in the c ell.The w eigh ting b y residenc e time is nec essar y because a par cel ma y pass thr ough mor e than one c ell within a c omputa tional time st ep and ther efore its c ontribution t o the a veraged c ell quan tities dep ends on the fr action of the time st ep sp ent in each c ell. The time-a veraged DPM v olume fr action is c alcula ted fr om the individual numb er of par ticles in the parcel, the par ticle v olume , and its r esidenc e time in the c ell in r elation t o the individual time st ep. The RMS v alue is also a vailable and is c omput ed fr om Equa tion 24.25 (p.2053 ). (24.25) Note tha t these quan tities ar e averaged o ver all par cels tha t ha ve passed thr ough the c ell and ar e ther efore diff erent from the instan taneous c ell-a veraged v alues descr ibed in Reporting of D iscrete Phase Variables (p.2050 ). If you ar e using Data S ampling f or Time S tatistics , the same w eigh ting is applied in the Unstead y DPM S tatistics ... categor y as descr ibed in Note on the C ell-A veraging of P article Variables (p.2052 ).That means tha t in the a veraging o ver time st eps, the phase v elocity in the c ell for a time st ep in which man y par cels sp end a long time in tha t cell is giv en a lar ger w eigh t than f or a time st ep in which fewer par cels sp end less time in the same c ell. Below is a list of the a vailable unst eady sta tistics when DPM Variables is enabled in the Sampling Options dialo g box.These ar e acc essible b y selec ting the Unstead y DPM S tatistics ... categor y in postpr ocessing or r eporting dialo g boxes. Note tha t the a vailabilit y of some quan tities dep ends on the ph ysics mo dels b eing used . For definitions of these quan tities , refer to the definitions of the in- stan taneous quan tities fr om which the y are der ived (see Alphab etical Listing of F ield Variables and Their D efinitions (p.2988 )). 2053Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Postpr ocessing f or the D iscrete PhaseUnstead y DPM S tatistics •Mean DPM Volume F raction •Accum DPM P articles in C ell •Mean DPM X, Y, Z Velocity •Mean DPM D iamet er •Mean DPM D ensit y •Mean DPM Temp erature •Mean DPM G ranular Temp erature •Mean DPM N umb er D ensit y •Accum DPM P arcels in C ell •Mean DPM D20 •Mean DPM D30 •Mean DPM D32 •Mean DPM D43 •RMS DPM Volume F raction •RMS DPM X, Y, Z Velocity •RMS DPM D iamet er •RMS DPM D ensit y •RMS DPM Temp erature •RMS DPM G ranular Temp erature •RMS DPM N umb er D ensit y Explana tions f or the Accum ... variables ar e pr ovided in Alphab etical Listing of F ield Variables and Their Definitions (p.2988 ). 24.8.8. Sampling of Trajec tories Particle sta tes (p osition, velocity, diamet er, temp erature, and mass flo w rate) can b e wr itten t o files a t various b oundar ies and planes (lines in 2D) using the Sample Trajec tories D ialog Box (p.3732 ) (Fig- ure 24.51: The S ample Trajec tories D ialog Box (p.2055 )). Results → Rep orts → Discr ete Phase → Sample Edit... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2054Modeling D iscrete PhaseFigur e 24.51: The S ample Trajec tories D ialo g Box The pr ocedur e for gener ating files c ontaining the par ticle samples is list ed b elow: 1.Selec t the injec tions t o be tracked in the Release F rom Injec tions list. 2.Selec t the sur faces a t which samples will b e wr itten These c an b e boundar ies fr om the Boundar ies list or planes fr om the Planes list (in 3D) or lines fr om the Lines list (in 2D). 3.If you w ant to use the par ticle sampling file as an unst eady injec tion file , selec t Sort Sample F iles. The Sort Sample F iles option c auses the sample files t o be sor ted in a r eproducible manner . For steady par ticle tr acking, files will b e sor ted first b y injec tion and then b y par ticle ID . For unst eady particle tr acking, the files will b e sor ted str ictly b y the simula ted time (flow-time in the 13th column in the sample file) a t which the par ticle passes the sampling plane sur face or mesh z one . 4.Click the Comput e butt on. Note tha t for unst eady par ticle tr acking, the Comput e butt on will b ecome the Start butt on (t o initia te sampling) or a Stop butt on (t o stop sampling). Clicking the Comput e butt on will c ause the par ticles t o be tracked and their sta tus t o be wr itten t o files when the y enc oun ter selec ted sur faces.The file names will b e formed b y app ending .dpm to the surface name . Note If you selec t a fac e zone in a mesh in terface for sampling , Fluen t will sample the par ticles on b oth of the in terface zones and will wr ite out a t otal of thr ee files .Two of these files c orrespond t o the par ticles tha t enc oun ter each r espective in terface zone fr om upstr eam. The thir d file c ontains the c omplet e set of par ticles tha t ha ve crossed the mesh in terface pair (via either in terface zone). For unst eady par ticle tr acking, click ing the Start butt on will op en the files and wr ite the file header sections . If the solution is ad vanced in time b y computing some time st eps, the par ticle tr ajec tories 2055Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Postpr ocessing f or the D iscrete Phasewill b e up dated and the par ticle sta tes will b e wr itten t o the files as the y cross the selec ted planes or boundar ies. Clicking the Stop butt on will close the files and end the sampling . For st ochastic tr acking, it ma y be useful t o repeat this pr ocess multiple times and app end the r esults to the same file , while monit oring the sample sta tistics a t each up date.To do this , enable the Append Files option b efore repeating the c alcula tion (click ing Comput e). Similar ly, you c an c ause er osion and accr etion r ates to be accumula ted f or repeated tr ajec tory calcula tions b y tur ning on the Accumula te Erosion/A ccretion R ates option. (See also Postpr ocessing of E rosion/A ccretion R ates (p.2063 ).) The f ormat and the inf ormation wr itten f or the sample output c an also b e controlled thr ough a user- defined func tion, which c an b e selec ted in the Output drop-do wn list. More inf ormation ab out user- defined func tions c an b e found in the Fluen t Customiza tion M anual . The gener ated sample files c an b e used as injec tion file in a file injec tion. Both files use the same file formats which diff er b etween st eady and unst eady par ticle tr acking. For details , see Point Properties for F ile Injec tions (p.1960 ). If the numb er of lines in the sampling file is lar ge, you c an r educ e it b y combining sets of similar line entries in to one single en try per such set. The mass r epresen ted b y tha t en try will b e incr eased acc ord- ingly t o ensur e mass c onser vation. For details , see Data R educ tion of S amples (p.2059 ). 24.8.9. Hist ogram Rep orting of S amples DPM sample files c an b e created using the Sample Trajec tories D ialog Box (p.3732 ) (as descr ibed in Sampling of Trajec tories (p.2054 )) or b y the VOF-t o-DPM mo del tr ansition mechanism. Such a file c ontains multiple r ecords, each c onsisting of v alues f or the same set of v ariables .You c an p ostpr ocess pr obab- ility distr ibutions and simple c orrelation analy ses of these v ariables using the Trajec tory Sample Hist o- grams D ialog Box (p.3733 ) (Figur e 24.52: The Trajec tory Sample Hist ograms D ialog Box (p.2057 )). Results → Rep orts → Discr ete Phase → Hist ogram Edit... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2056Modeling D iscrete PhaseFigur e 24.52: The Trajec tory Sample Hist ograms D ialo g Box 24.8.9.1. Anal ysis, Investigation, and R eporting of S amples The basic pr ocedur e for plotting a hist ogram of the pr obabilit y distr ibution of a v ariable r ead fr om data in a sample file is list ed b elow: 1.Selec t a sample file t o be read b y click ing the Read ... butt on. After you r ead in the sample file , the sample name will app ear in the Sample list. 2.Selec t the da ta sample in the Sample list, and then selec t the v ariable f or which t o plot the pr obabilit y distr ibution hist ogram fr om the Variable list. 3.Selec t the v ariable b y which t o weigh t the file individual line en tries fr om the Weigh t list. To obtain represen tative inf ormation f or most in tensiv e variables , such as t emp erature, velocity, or p osition, you should selec t: •mass-flo w for a sample file fr om st eady-sta te par ticle tr acking •par cel-mass for a sample file fr om unst eady par ticle-tr acking. If the sampled par ticle str eams / par cels all ha ve the same flo w rate / par cel mass , you c an clear Weigh ting . 2057Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Postpr ocessing f or the D iscrete Phase4.You c an sp ecify the numb er of bins , or in tervals, in the plot in the Divisions field under Hist ogram Paramet ers. 5.If you w ant to plot just some par t of the pr obabilit y distr ibution, clear Auto Range and sp ecify the r ange of values in the Min and Max fields under Hist ogram P aramet ers.You c an r eset Min and Max to the complet e range b y click ing Comput e. 6.If variable v alues y ou ar e investiga ting span se veral or ders of magnitude , you c an use lo garithmic sc aling of the bins b y selec ting Logarithmic under Hist ogram Options . Note tha t this option is a vailable only for the v ariables tha t tak e only p ositiv e values .With this option, you should selec t the lo garithmic sc aling format for the abscissa and , if nec essar y, for the or dina te in the Axes dialo g box tha t op ens b y click ing Axes… (Hist ogram P aramet ers group b ox). 7.Click the Plot butt on a t the b ottom of the dialo g box to displa y the hist ogram in the gr aphics windo w. By default , the p ercentages of the t otal amoun t measur ed b y the w eigh ting v ariable will b e plott ed on the axis .You c an plot the ac tual numb er of sampled par ticle str eams / par cels (tha t is, line entries fr om the file tha t fall in to each in terval on the axis) b y clear ing Percent under Hist ogram Options . If Weigh ting is selec ted, the sum of the w eigh ts of all en tries in each bin will b e plott ed instead of the numb er. To displa y a pr obabilit y densit y func tion cur ve inst ead of the hist ogram, clear Hist ogram M ode under Hist ogram Options .You c an enable the displa y of da ta p oint mar kers in the plot using the Curves dialo g box tha t op ens b y click ing Curve.... If you w ant to displa y in the c onsole a summar y for the selec ted v ariables similar t o tha t in Summar y Reporting of C urrent Particles (p.2061 ), selec t Diamet er S tatistics and click Plot. Although these sta t- istics ar e comput ed f or an y selec ted v ariable in the Variable list, it is applic able only t o the diamet er information. If you w ant to fur ther p ostpr ocess the plot da ta with other sof tware tools, you c an st ore them in an XY-plot file f ormat using the Write... butt on. If you use the default filename e xtension .his , the file be wr itten with a header .The header lines b egin with the c ommen t char acter ; and c ontain the same statistic al inf ormation tha t is pr inted t o the F luen t console when y ou click Plot. If you w ant to remo ve the cur rently highligh ted sample fr om the Sample list and delet e it fr om the ANSY S Fluen t session memor y, but not the c orresponding file , click Delet e. When in vestiga ting the b ehavior of par ticles , it is sometimes desir able t o know ho w one par ticle variable c orrelates with another par ticle v ariable .To facilita te this , the Correlation option e xists .When you enable this option, an additional c olumn of sampled v ariables app ears , allo wing y ou t o cho ose the c orrelation v ariable (see Figur e 24.53: The Trajec tory Sample Hist ograms D ialog Box: Correla- tion (p.2059 )). In this mo de, every or dina te value will b e a w eigh ted a verage of the v alues of the c or- relation v ariable in all en tries tha t fall in to the r espective bin. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2058Modeling D iscrete PhaseFigur e 24.53: The Trajec tory Sample Hist ograms D ialo g Box: Correlation If you w ant to plot the c ontinuous cumula tive distr ibution func tion, enable the Cumula tive Curve option. A cumula tive distr ibution cur ve is c omput ed of the v ariable tha t is selec ted in the Variable list using the w eigh ting options . However, if the Correlation option is enabled along with the Cumu- lative Curve, then the cumula tive cur ve of the v ariable selec ted in the Correlation list is plott ed. For a constan t par ticle densit y, you c an plot a c orrelation cur ve for the par ticle mass b y selec ting the diamet er as a Correlation variable and enabling (Variable)ˆ3 .This c alcula tes cub es of the v ariable chosen under Correlation and f or which an a verage is c alcula ted within each bin and used f or the ordina te value in the plot as e xplained ab ove. 24.8.9.2. Data R educ tion of S amples When y ou use a sample file as an injec tion file in a subsequen t simula tion, it ma y be desir able t o reduc e the numb er of par ticles injec ted b y the file in or der t o lo wer the c omputa tional c ost. In ANSY S Fluen t this c an b e done b y reducing the numb er of lines the sample file c ontains using a metho d tha t is similar t o tha t used t o cr eate a hist ogram. However, unlik e a hist ogram, the w eigh ted en tries fr om the sample file ar e sor ted in to in tervals f or all v ariables simultaneously , not one v ariable a t a time . The metho d first sor ts all file en tries in to gr oups , or bins , of en tries tha t are sufficien tly similar in all properties.The en tries tha t ha ve fallen in to the same bin ar e then a veraged t o cr eate a single en try. Conser vation of mass and v olume as w ell as the numb er of par ticles is achie ved b y appr opriate weigh ting in the a veraging pr ocess. To reduc e a sample file siz e: 1.Read a sample file as descr ibed in Analy sis, Investiga tion, and R eporting of S amples (p.2057 ). 2.Selec t the da ta sample in the Sample list. 2059Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Postpr ocessing f or the D iscrete Phase3.Selec t Data F ile Reduc tion . The Trajec tory Sample Hist ograms dialo g box will e xpand t o sho w the Scale, No. of Bins list (between the Variable and Weigh t lists) and da ta file r educ tion inputs . Figur e 24.54: The Trajec tory Sample Hist ograms D ialo g Box: Data F ile Reduc tion 4.For each v ariable in the Variable list, specify the f ollowing par amet ers in the Data Reduc tion in the Selec ted Variable group b ox: 1st Bin M in,Last Bin M ax limit the r ange of v alues t o consider . Note tha t the c omplet e range f or the selec ted v ariable is displa yed in the Min and Max fields in the Hist ogram P aramet ers group b ox.You c an use the Reset butt on to reset 1st Bin M in and Last Bin M ax to their or iginal v alues . LOG Sc ale enables the use of a lo garithmic sc ale.The b ehavior of this option is analo gous t o the Logarithmic option in Hist ogram Options (see Analy sis, Investiga tion, and R eporting of S amples (p.2057 )). By de- fault , the linear sc aling is used .This option is a vailable only if all v alues f or the v ariable in the sample file ar e positiv e. No. of Bins the numb er of gr oups in to which the sp ecified r ange f or this v ariable is t o be divided . If you w ant to neglec t an y variable , set No. of Bins to 1. If you w ant to set the v alue y ou sp ecified f or all v ariables , click Set N o. of Bins f or A ll Variable . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2060Modeling D iscrete PhaseOnc e you ha ve sp ecified 1st Bin M in,Last Bin M ax, and No. of Bins , you c an click Update to see the Resulting Bin S ize. If the LOG Sc ale is selec ted, the v alue sho wn in the Resulting Bin Size is the r atio f or LOG Sc ale. You c an quick ly review the inputs f or the sc aling and numb er of bins f or each v ariable in the Scale, No. of Bins information list. 5.For a standar d DPM sample file gener ated b y ANSY S Fluen t, you should use the default w eigh ting . However, if you w ant to reduc e da ta in a file tha t do es not c ontain the default header and v ariable columns tha t are pr esen t in a standar d DPM sample file , you c an selec t a w eigh ting v ariable manually from the Weigh t list. If you do not w ant to use the w eigh t, clear the Weigh ting option in the Data Re- duc tion Options group b ox. Note tha t in b oth sc enar ios, the r educ ed sample file ma y not r epresen t the same mass , volume , and flo w rates of discr ete phase . 6.If the or iginal sample file w as gener ated fr om unst eady par ticle tr acking, you c an r educ e the unst eady sample file t o a r egular st eady-sta te injec tion file b y selec ting the Create Stead y from U nstead y check box in the Data Reduc tion Options group b ox.This option is a vailable only f or sample files fr om unst eady particle tr acking. 7.Onc e you ha ve configur ed the da ta reduc tion settings f or all v ariables and selec ted the da ta reduc tion options , click Reduc e.... 8.In The S elec t File D ialog Box (p.569) tha t op ens aut oma tically, enter the name of y our r educ ed injec tion sample file . The numb er of aggr egated r ecords will b e reported in the ANSY S Fluen t console . 24.8.10. Summar y Rep orting of C urrent Particles For man y mass-tr ansf er and flo w pr ocesses , it is desir able t o know the mean diamet er of the par ticles . A mean diamet er, , is c alcula ted fr om the par ticle siz e distr ibution using the f ollowing gener al ex- pression [62] (p.4008 ): (24.26) wher e and are in tegers and is the distr ibution func tion (f or e xample , Rosin-R ammler). , for e xample , is the a verage (ar ithmetic) par ticle diamet er.The S auter mean diamet er (SMD), , is the diamet er of a par ticle whose r atio of v olume t o sur face ar ea is equal t o tha t of all par ticles in the computa tion. A summar y of c ommon mean diamet ers is giv en in Table 24.6: Common M ean D iamet ers and Their F ields of A pplic ation (p.2061 ). Table 24.6: Common M ean D iamet ers and Their F ields of A pplic ation Field of A pplic ation Name Order Compar isons , evaporationMean diamet er, 1 0 1 Absor ptionMean sur face diamet er, 2 0 2 HydrologyMean v olume diamet er, 3 0 3 2061Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Postpr ocessing f or the D iscrete PhaseField of A pplic ation Name Order Adsor ptionOverall sur face diamet er, 3 1 2 Evaporation, molecular diffusionOverall v olume diamet er, 4 1 3 Combustion, mass tr ansf er, and efficienc y studiesSauter mean diamet er, 5 2 3 Combustion equilibr iumDe Brouck ere diamet er, 7 3 4 Summar y inf ormation (numb er, mass , average diamet er) f or par ticles cur rently in the c omputa tional domain c an b e reported using the Particle Summar y Dialog Box (p.3736 ) (Figur e 24.55: The P article Summar y Dialog Box (p.2062 )) Results → Rep orts → Discr ete Phase → Summar y Edit... Figur e 24.55: The P article S ummar y D ialo g Box The pr ocedur e for reporting a summar y for par ticle injec tions is as f ollows: 1.Selec t the par ticle injec tion(s) y ou w ant summar ized in the Injec tions list. Fluen t provides a shor tcut f or selec ting injec tions with names tha t ma tch a sp ecified pa ttern.To use this shor tcut, enter the pa ttern in the Filter Text box. For e xample , if y ou sp ecify drop* , all injec tions tha t ha ve names b eginning with drop (for e xample ,drop-1 ,droplet ) will b e list ed. 2.Click Summar y to displa y the injec tion summar y in the c onsole windo w. (*)- Summary for Injection: injection-0 -(*) Total number of parcels : 1862 Total number of particles : 1.196710e+05 Total mass : 1.128303e-05 (kg) Maximum RMS distance from injector : 7.372527e-01 (m) Maximum particle diameter : 3.072739e-04 (m) Minimum particle diameter : 1.756993e-06 (m) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2062Modeling D iscrete Phase Overall RR Spread Parameter : 1.446806e+00 Maximum Error in RR fit : 1.071220e-01 Overall RR diameter (D_RR): 9.051303e-05 (m) Overall mean diameter (D_10): 4.663269e-05 (m) Overall mean surface area (D_20): 5.344694e-05 (m) Overall mean volume (D_30): 6.121478e-05 (m) Overall surface diameter (D_21): 6.125692e-05 (m) Overall volume diameter (D_31): 7.013570e-05 (m) Overall Sauter diameter (D_32): 8.030141e-05 (m) Overall De Brouckere diameter (D_43): 1.082971e-04 (m) 24.8.11. Postpr ocessing of E rosion/A ccretion R ates You c an c alcula te the er osion and accr etion r ates in a cumula tive manner (o ver a ser ies of injec tions) by using the Sample Trajec tories dialo g box. First selec t an injec tion in the Release F rom Injec tions list and c omput e its tr ajec tory.Then enable the Accumula te Erosion/A ccretion R ates option, selec t the ne xt injec tion (af ter deselec ting the first one), and click Comput e again. The r ates will accumula te at the sur faces each time y ou click Comput e. Imp ortant Both the er osion r ate and the accr etion r ate ar e defined a t wall fac e sur faces only , so the y cannot b e displa yed a t no de v alues . 24.8.12. Assessing the R isk f or S olids D eposit F ormation D uring S elec tive Catalytic Reduc tion P rocess ANSY S Fluen t provides func tionalit y for assessing the solids dep osition r isk in the S elec tive Catalytic Reduc tion (SCR) pr ocess.The c omputa tion in volves se veral chemic al and h ydrodynamic r isk fac tors that are based on ther modynamic da ta and k nown chemic al pa thw ays, as w ell as on e xperimen tal evidenc e reported in the lit erature ([121] (p.4011 ),[127] (p.4012 ),[14] (p.4005 ),[105] (p.4010 ), and [146] (p.4013 )).The r isk assessmen t calcula tion should b e invoked af ter the initial liquid film f ormation on the sur faces of the SCR de vice, and should c over a time p eriod over one or mor e ur ea injec tion cycles .The r isk v ariables ar e defined as dimensionless quan tities tha t vary from 0 t o 1, wher e 0 c orres- ponds t o no r isk and 1 c orresponds t o maximum r isk. Note tha t the r isk assessmen t calcula tion is not a pr edic tive mo del f or ur ea dep osit f ormation, and the obtained r esults should b e consider ed only as rough guidanc e in e xplor ing ur ea dep osit f ormation tr ends . The implemen tation tak es in to acc oun t the f ollowing chemistr y risk fac tors: •Crystalliza tion r isk The limiting ur ea mass fr action for the onset of cr ystalliza tion is a func tion of film t emp er- ature ([121] (p.4011 ) and [105] (p.4010 )).Therefore, the cr ystalliza tion r isk o ver the time period – can b e calcula ted as the fr action of time when the ur ea mass fr action in the liquid film exceeds : (24.27) •Secondar y reactions r isk 2063Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Postpr ocessing f or the D iscrete PhaseAccording t o [121] (p.4011 ),[127] (p.4012 ), and [14] (p.4005 ), the f ormation of biur et and/or c yanur ic acid solids dep osits star ts at = 423-433 K and diminishes a t = 523 K. In addition, the presenc e of HNC O in the gas phase ab ove the film is r equir ed. It follows tha t the sec ondar y reactions r isk o ver the time p eriod – can b e calcula ted as the fr action of time when the liquid film is e xposed t o a non-z ero HNC O concentration and the film t emp erature is b etween and as sp ecified ab ove. (24.28) In addition, the f ollowing h ydrodynamic fac tors ha ve been sho wn t o aff ect solids dep osit f ormation trends: •Intense d ynamics c an b e quan tified as fluc tuations of film heigh t [121] (p.4011 ).When the fluc tuations ar e high, the r isk of dep osit f ormation is imp eded . •As reported b y Smith et al. [121] (p.4011 ), thick film and high film v elocity indic ates lo w dep osit f ormation risk, while B rack et al. [146] (p.4013 ) report tha t thick film and lo w hea t flux indic ate high dep osit f ormation risk. Accordingly , ANSY S Fluen t uses the f ollowing definitions t o quan tify the h ydrodynamic r isk fac tors: •Velocity-based r isk (24.29) •Heat-flux based r isk (24.30) wher e = (Wall F ilm H eigh t) / (M aximum F ilm H eigh t) =(Wall F ilm Velocity) / (M aximum Wall F ilm Velocity) = (Wall F ilm H eat Flux) / (M aximum Wall F ilm H eat Flux) Finally , averaging o ver the p eriod from to and applying appr opriate weigh ting fac tors, the t otal risk is c alcula ted as: (24.31) wher e: (24.32) (24.33) The w eigh ting fac tors . , , and are user-sp ecified v alues . You c an acc ess the func tionalit y for assessing the r isk of solids dep osit f ormation via the f ollowing text commands: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2064Modeling D iscrete Phasedefine/models/dpm/options/scr-urea-deposition-risk-analysis/enable? yes You will b e ask ed t o define the w all z ones wher e the r isk assessmen t should b e performed , for e xample: Wall face zones(1) [()] 8 The implemen tation uses the da ta sampling and cust om field func tions in ANSY S Fluen t, and af ter enabling the r isk assessmen t capabilit y, the f ollowing st eps ar e aut oma tically p erformed: •Defining appr opriate solution r eport definitions f or calcula ting the maximum film heigh t, velocity, and heat-flux. •Defining the r equir ed cust om field func tions f or calcula ting the r isk fac tors. •Enabling da ta sampling on the cust om field func tions . Onc e the SCR ur ea dep osition r isk analy sis is enabled , you c an set the f ollowing par amet ers and weigh ting fac tors (a vailable under define/models/dpm/options/scr-urea-deposition- risk-analysis/) : •cryst-min-temp and cryst-max-temp : the minimum and maximum film t emp eratures for the onset of ur ea cr ystalliza tion (K), respectively •cryst-min-mass-fract : the minimum ur ea mass fr action f or the onset of ur ea cr ystalliza tion as defined in [121] (p.4011 ) and [105] (p.4010 ) •seco-rx-min-hnco : the minimum HNC O mass fr action in the gas phase ab ove the liquid film f or sec- ondar y reactions ( in Equa tion 24.28 (p.2064 )) •seco-rx-min-temp and seco-rx-max-temp : the minimum and maximum film t emp eratures for secondar y reactions (K), respectively ( and in Equa tion 24.28 (p.2064 )) •hydrodynamic-risk-weight : weigh ting fac tor for h ydrodynamic r isk ( in Equa tion 24.31 (p.2064 )) •cryst-depo-weight : weigh ting fac tor for cr ystalliza tion r isk ( in Equa tion 24.32 (p.2064 )) •velocity-based-risk-weight : weigh ting fac tor for v elocity based r isk ( in Equa tion 24.33 (p.2064 )) •heat-flux-based-risk-weight : weigh ting fac tor for hea t-flux based r isk ( in Equa- tion 24.33 (p.2064 )) •wall-face-zones : wall z one list f or solids dep osit r isk pr edic tion After the time-dep enden t calcula tion is c omplet ed, the f ollowing v ariables will b e available under Custom F ield F unc tions ... categor y for p ost-pr ocessing: •scr-ur ea-o verall-h ydrodynamic-dep osition-r isk: is in Equa tion 24.33 (p.2064 ) •scr-ur ea-o verall-chemistr y-dep osition-r isk: is in Equa tion 24.32 (p.2064 ) •scr-ur ea-t otal-dep osition-r isk: in Equa tion 24.31 (p.2064 ) Additional field v ariables r eported under the Custom F iled F unc tions ... and SCR U rea D eposition Risk A naly sis... categor ies ar e the f ollowing: 2065Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Postpr ocessing f or the D iscrete Phase•scr-ur ea-dep o-risk-v elocity-based (in the Custom F iled F unc tions ... categor y): in Equa tion 24.29 (p.2064 ) •scr-ur ea-dep o-risk-hea t-flux-based (in the Custom F iled F unc tions ... categor y): in Equa- tion 24.30 (p.2064 ) •SCR U rea C rystalliza tion R isk (in the SCR U rea D eposition R isk A naly sis... categor y): is the chemistr y based r isk r epresen tation in Equa tion 24.27 (p.2063 ) •SCR U rea S econdar y Reac tions R isk (in the SCR U rea D eposition R isk A naly sis... categor y): is the chemistr y based r isk r epresen tation in Equa tion 24.28 (p.2064 ) •SCR O verall U rea C hemic al D eposition R isk (in the SCR U rea D eposition R isk A naly sis... categor y): is the chemistr y based r isk r epresen tation in Equa tion 24.32 (p.2064 ) You ma y ignor e the additional v ariables with the scr-ur ea-dep o- prefix in the Custom F iled F unc tions ... categor y as the y are in termedia te quan tities with no meaning ful v alues . 24.9. Parallel P rocessing f or the D iscr ete Phase M odel ANSY S Fluen t off ers thr ee mo des of par allel pr ocessing f or the discr ete phase mo del: •Shared M emor y The Shared M emor y metho d is suitable f or c omputa tions wher e the machine r unning the ANSY S Fluen t host pr ocess is an adequa tely lar ge, shar ed-memor y, multipr ocessor machine . •Message P assing The Message P assing option is suitable f or gener ic distr ibut ed memor y clust er computing . •Hybr id (default) The Hybr id option is suitable f or mo dern multic ore memor y clust er computing . These options ar e found under the Parallel tab , in the Discr ete Phase M odel dialo g box. Imp ortant Note the f ollowing: •When tr acking par ticles with the DPM mo del in c ombina tion with an y of the multiphase flo w models ( VOF, mix ture, or E uler ian) the Shared M emor y metho d cannot b e selec ted. (Note tha t using the Message P assing or Hybr id metho d enables the c ompa tibilit y of all multiphase flo w models with the DPM mo del.) •Starting in v ersion 18.2, the Shared M emor y metho d is not c ompa tible with ser ial UDFs when running in ser ial. If you w ant to use file injec tions or t o wr ite a DPM summar y report dir ectly t o a file , your sy stem must meet the f ollowing r equir emen ts when either the Message P assing or Hybr id par allel DPM tr acking option is selec ted: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2066Modeling D iscrete Phase•The machine (f or e xample , clust er no de) r unning the c omput e-no de z ero pr ocess and the machine r unning the host pr ocess ar e iden tical or ha ve the same op erating sy stem t ype (Windo ws or Linux) •Both machines c an acc ess the same file sy stem thr ough the same pa th sp ecific ation If these c onditions ar e not met , you c an still wr ite a DPM summar y report to a file b y star ting tr anscr ipt, reporting the par ticle tr acking summar y to the F luen t console , and then st opping tr anscr ipt.The summar y report will b e sa ved in the tr anscr ipt file . As a w orkaround f or the DPM summar y report, you c an star t transcr ipt, report the par ticle tr acking summar y to the F luen t console , and st op tr anscr ipt.The summar y report will b e sa ved in the tr anscr ipt file The Shared M emor y option ( Figur e 24.56: The S hared M emor y Option with Workpile A lgor ithm En- abled (p.2068 )) is implemen ted using POSIX Threads (pthr eads) based on a shar ed-memor y mo del. Onc e the Shared M emor y option is enabled , you c an then selec t along with it the Workpile A lgor ithm and specify the Numb er of Threads . By default , the Numb er of Threads is equal t o the numb er of c omput e nodes sp ecified f or the par allel c omputa tion. You c an mo dify this v alue based on the c omputa tional requir emen ts of the par ticle c alcula tions . If, for e xample , the par ticle c alcula tions r equir e mor e compu- tation than the flo w calcula tion, you c an incr ease the Numb er of Threads (up t o the numb er of a vailable processors) t o impr ove performanc e.When using the Shared M emor y option, the par ticle c alcula tions are en tirely managed b y the ANSY S Fluen t host pr ocess.You must mak e sur e tha t the machine e xecuting the host pr ocess has enough memor y to acc ommo date the en tire mesh. Imp ortant Note tha t the Shared M emor y option on Windo ws-based ar chitectures only pr ovides ser ial tracking on the host , sinc e the Workpile A lgor ithm is not a vailable due t o lack of POSIX Threads on these pla tforms. Imp ortant Note tha t the Workpile A lgor ithm option is not a vailable with the w all film b oundar y con- dition. It will b e disabled aut oma tically when cho osing t o simula te a w all film on a w all. 2067Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Parallel P rocessing f or the D iscrete Phase M odelFigur e 24.56: The S hared M emor y Option with Workpile A lgor ithm E nabled The Message P assing option enables clust er computing and also w orks on shar ed-memor y machines . With this option enabled , the c omput e no de pr ocesses p erform the par ticle w ork on their lo cal par titions . Particle migr ation t o other c omput e no des is implemen ted using message passing pr imitiv es.There ar e no sp ecial r equir emen ts for the host machine . Note tha t this mo del is not a vailable if the Cloud M odel option is tur ned on under the Turbulen t Dispersion tab of the Set Injec tion P roperties dialo g box. By default , pathline displa ys are comput ed in ser ial on the host no de. Pathline displa ys ma y be comput ed in par allel on distr ibut ed memor y sy stems if the Message P assing par allel option is selec ted in the Discr ete Phase M odel dialo g box. The Hybr id option c ombines Message P assing and OpenMP for a d ynamic load balancing without migr ation of c ells, enables multic ore clust er computing , and also w orks on shar ed-memor y machines . With this option enabled , the c omput e no de pr ocesses p erform the par ticle c alcula tions on their lo cal partitions .OpenMP threads will b e spa wned , and the numb er of thr eads in each ANSY S Fluen t no de process is based on the e valua tion of the par ticle load on the cur rent machine .The maximum numb er of thr eads on each machine c an b e controlled using the Thread C ontrol dialo g box (see Controlling the Threads (p.3095 ) for details). The default v alue is the numb er of ANSY S Fluen t no de pr ocesses on each machine . Particle migr ation t o other c omput e no des is implemen ted using message passing primitiv es.There ar e no sp ecial r equir emen ts for the host machine . Note tha t this mo del is not a vailable Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2068Modeling D iscrete Phaseif the Cloud M odel option is tur ned on under the Turbulen t Dispersion tab of the Set Injec tion Properties dialo g box. Pathline displa ys are comput ed b y default in ser ial on the host no de. Pathline displa ys ma y also b e comput ed in par allel on distr ibut ed memor y sy stems if the Message P assing option is selec ted fr om the Metho ds list. For a list of limita tions tha t exist with H ybrid par allel metho d, see Limita tions on U sing the H ybrid P arallel M etho d (p.1916 ). When using the H ybrid metho d, you ma y optionally enable Use DPM D omain under Hybr id Options . This option c an pr ovide substan tially impr oved load balancing , and thus sc alabilit y, at the e xpense of additional memor y overhead .When Use DPM D omain is enabled , par ticle tr acking is p erformed on a separ ate domain fr om the r oot c omputa tional domain. Flow and DPM v ariables ar e copied b etween the domains as par t of the solution pr ocess. By using a separ ate domain, and thus par titioning str ategy, for par ticle tr acking the c ontinuous and discr ete phase loads ar e balanc ed indep enden tly.This allo ws the load t o be shar ed mor e equally among the machines r egar dless of ho w par ticles ar e distr ibut ed throughout the c omputa tional domain. This is esp ecially b eneficial f or simula tions with non-unif orm particle distr ibutions o ver the c omputa tional domain. For limita tions asso ciated with the Use DPM Domain option, see Limita tions on U sing the H ybrid P arallel M etho d (p.1916 ).With this option, you ma y also w ant to use the f ollowing t ext commands: •parallel → partition → set → dpm-load-balancing This t ext command enables d ynamic load balancing .You will b e pr ompt ed t o define a load imbalanc e threshold (tha t is, a p ercentage ab ove which load balancing will o ccur), as w ell as the in terval of DPM iterations a t which y ou w ould lik e load balancing a ttempt ed. It is r ecommended tha t you r etain the default v alues , as these ar e appr opriate for a wide r ange of c ases . •define → models → dpm → parallel → expert → partition-method-hybrid-2domain This enables a par titioning metho d tha t is mor e gr anular and c an yield fast er calcula tions (esp ecially for c ases tha t are running on a lo w to mo derate numb er of pr ocessors). You ma y seamlessly swit ch among the Shared M emor y option, the Message P assing option, and the Hybr id option a t an y time dur ing the ANSY S Fluen t session. In addition t o performing gener al par allel pr ocessing of the D iscrete Phase M odel, you ha ve the option of implemen ting DPM-sp ecific user-defined func tions in par allel ANSY S Fluen t. For mor e inf ormation about the par alleliza tion of DPM UDFs , see Paralleliza tion of D iscrete Phase M odel (DPM) UDFs in the Fluen t Customiza tion M anual . When using the Message P assing or the Hybr id option y ou c an mak e use of ANSY S Fluen t’s aut oma ted load balancing c apabilit y by giving an appr opriate weigh t to the par ticle st eps in each c ell. In this c ase the numb er of par ticle st eps in each par tition is c onsider ed in the load balancing pr ocedur e. Further details c an b e found in Using the P artitioning and L oad B alancing D ialog Box (p.3071 ). 2069Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Parallel P rocessing f or the D iscrete Phase M odelRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2070Chapt er 25: Modeling M acroscopic P articles Traditional Lagr angian discr ete phase mo dels only apply when par ticle siz es ar e small enough t o be regar ded as p oint masses within a single c ell and when the t otal par ticle v olume is insignific ant within the flo w domain v olume . In these applic ations par ticle-par ticle and par ticle-flo w in teractions ar e evalua ted in terms of impulse , hea t, and mass tr ansf er. However, the t otal par ticle v olume must b e consider ed when a par ticle siz e is lar ger than se veral fluid cells b ecause it will aff ect all the c ells within the flo w domain v olume . ANSY S Fluen t Macroscopic P article Model (MPM) pr edic ts the b ehavior of lar ge (macr oscopic) par ticles and their in teraction with the fluid flow, walls, and with other par ticles . This chapt er pr ovides an o verview of ho w to use the MPM add-on mo dule in ANSY S Fluen t. For mor e information ab out the theor etical back ground f or the MPM mo deling appr oach, see Modeling M acro- scopic P articles . 25.1. Overview and Limita tions 25.2. Loading the MPM add-on M odule 25.3. Setting up MPM M odel S imula tions 25.4. Modeling M acroscopic P articles 25.1. Overview and Limita tions The MPM is an add-on mo dule based on a suit e of UDF func tions tha t mo dels tr ansp ort of lar ge par ticles in a fluid flo w, par ticle-par ticle and par ticle-w all in teractions , as w ell as par ticle tr acking.The MPM is designed f or macr oscopic par ticles tha t are well-r esolv ed acr oss a par ticle diamet er b y at least 20-30 fluid c ells. The MPM is not a gener al pur pose mo del. The mo del has b een sho wn t o giv e go od results f or applic ations in which macr oscopic par ticles with R eynolds numb er << 1 mo ve in a flo w ha ving a fluid-t o-par ticle densit y ratio, , in the or der of 1. For other v alues of and , the dr ag pr edic tion ma y not be accur ate; in such c ases the MPM mo del ma y be used when dr ag is not imp ortant. Note the f ollowing limita tions when using the MPM: •Mass tr ansf er and r adia tion c annot b e mo deled . •The MPM is not c ompa tible with mo ving/def orming meshes . •Simula tions of densely-pack ed par ticles ar e not supp orted b ecause only one c ollision e vent is handled f or each par ticle time st ep. •There is no dir ect interaction with DPM par ticles (c ollision). •Coupling with M ultiphase mo dels is p ossible , but manual settings ar e requir ed f or sour ce terms (mass , momen tum, and hea t). •Sub-it erations of MPM par ticle tr acks within one time st ep ar e not supp orted. 2071Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.•The MPM is not c ompa tible with mesh in terfaces. 25.2. Loading the MPM add-on M odule The MPM add-on mo dule is installed with the standar d installa tion of ANSY S Fluen t in a dir ectory called addons /mpm .The MPM add-on mo dule is loaded in to ANSY S Fluen t thr ough the t ext user in terface (TUI). Note tha t the mo dule c an b e loaded only when a v alid ANSY S Fluen t case file has b een set or read.To load the MPM add-on mo dule , issue the f ollowing TUI c ommand in the F luen t console: define → models → addon-module A list of ANSY S Fluen t add-on mo dules is displa yed in the c onsole: Fluent Addon Modules: 0. none 1. MHD Model 2. Fiber Model 3. Fuel Cell and Electrolysis Model 4. SOFC Model with Unresolved Electrolyte 5. Population Balance Model 6. Adjoint Solver 7. Single-Potential Battery Model 8. Dual-Potential MSMD Battery Model 9. PEM Fuel Cell Model 10.Macroscopic Particle Model Enter Module Number: [0] 10 Selec t the M acroscopic P article M odel b y en tering the mo dule numb er 10. During the loading pr ocess, a Scheme libr ary containing the gr aphic al and t ext user in terface, and a UDF libr ary containing a set of user-defined func tions (UDFs) f or the MPM add-on mo dule ar e aut oma tically loaded in to ANSY S Fluen t. This pr ocess is r eported in the F luen t console . Onc e the MPM mo dule is loaded in to ANSY S Fluen t, the Macroscopic P articles mo del app ears under the Models tree br anch, and the UDF libr ary also b ecomes visible as a new en try in the UDF Libr ary M anager dialo g box. By default , the Macroscopic P articles model is enabled . Note The MPM mo del is only a vailable in 3D . 25.3. Setting up MPM M odel S imula tions The f ollowing pr ocedur e pr ovides an o verview of the st eps r equir ed f or setting up and solving an MPM model c ase. Only the st eps tha t are pertinen t to MPM mo deling ar e sho wn her e. For inf ormation ab out inputs r elated t o other mo dels tha t you w ant to use in c onjunc tion with the MPM mo del, see the ap- propriate sec tions f or those mo dels in the ANSY S Fluen t User's G uide (p.1). 1. Use F luen t Launcher t o star t the 3D version of ANSY S Fluen t. 2. Read the c ase or mesh file . 3. Scale the mesh, if nec essar y. 4. For most c ases e xcept f or cemen ted par ticles simula tions , selec t the Transien t solv er fr om the Time list in the Gener al task page . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2072Modeling M acroscopic P articles5. Define the b oundar y conditions and ph ysical pr operties f or fluid flo w as usual. 6. (optional) Initializ e the flo w variables and r un the flo w simula tion un til the flo w converges. This st ep c ould b e performed t o impr ove solution stabilit y. Using a c onverged flo w solution as a starting p oint for an MPM simula tion c an b e par ticular ly helpful in situa tions wher e ther e is a str ong influenc e of macr oscopic par ticles on the fluid flo w. 7. Use the Macroscopic P article M odel dialo g box to sp ecify the par amet ers f or the MPM simula tion. 8. Initializ e either the MPM mo del as descr ibed in the sec tions tha t follow or the flo w field in the usual w ay. 9. Run the MPM simula tion. 10. Save the c ase and da ta files , if desir ed. 11. Review the simula tion r esults b y gener ating plots or alphanumer ic reports using the ANSY S Fluen t post- processing facilities . 25.4. Modeling M acroscopic P articles You c an set the MPM mo del par amet ers and selec t the options tha t are appr opriate for y our simula tion using the Macroscopic P article M odel dialo g box tha t op ens fr om the Setup /Models /Macroscopic Particle tree it em. From the Macroscopic P article M odel dialo g box, you c an acc ess the Create/M odify Injec tion dialo g boxes, wher e you c an set the macr oscopic par ticle injec tion pr operties. Setup → Models → Macroscopic P article Edit... Figur e 25.1: Macroscopic P article M odel D ialo g Box (P article Track ing Tab) 2073Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling M acroscopic P articlesThe inputs f or the MPM mo del ar e en tered using the f ollowing tabs: Particle Track ing is wher e you c an define par amet ers f or par ticle tr acking. Drag contains dr ag la w options and par amet ers f or the par ticle dr ag c alcula tions . Collision allows you t o enable par ticle-par ticle and par ticle-w all c ollisions and define the c ollision par amet ers. Deposition allows you t o enable par ticle dep osition on selec ted sur faces and par ticles and define the r elevant par a- met ers. Injec tions allows you t o define macr oscopic par ticle injec tions . Attraction F orces is wher e you c an sp ecify par amet ers f or par ticle-par ticle and par ticle-w all a ttraction f orces. Initializ e MPM contains c ontrols f or initializing the macr oscopic par ticles and displa ying par ticle injec tions . Note The default settings ma y not b e appr opriate for y our c ase.You must pr ovide par amet er da ta for y our sp ecific ma terial. For additional inf ormation, see the f ollowing sec tions: 25.4.1. Specifying P article Tracking P aramet ers 25.4.2. Specifying the D rag La w 25.4.3. Defining P aramet ers f or P article-P article and P article-W all C ollisions 25.4.4. Specifying D eposition P aramet ers 25.4.5. Specifying Injec tion P aramet ers 25.4.6. Defining F ield F orces 25.4.7. Initializing the MPM mo del 25.4.1. Specifying P article Track ing P aramet ers You c an use the Particle Track ing tab t o control the solution pr ocess of the MPM tr ajec tory equa tions using the f ollowing settings (see Figur e 25.1: Macroscopic P article M odel D ialog Box (Particle Tracking Tab) (p.2073 )): Particle Z ones contains a selec table list of the c ell z ones in which y ou c an use the MPM mo del. Enable In teraction with C ontinuous P hase (if selec ted) enables t wo-w ay coupling b etween par ticles and fluid flo w. Particle S ub-T imest eps within each F low Timet ep is a numb er of sub-time st eps f or par ticle tr acking in each flo w time st ep. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2074Modeling M acroscopic P articlesUnder-Relaxa tion F actor t o Velocities in Touched C ells By default the under-r elaxa tion fac tor for fixing v elocities is set t o 1. Solve Heat Transf er enables solving the ener gy equa tion. When this option is enabled , you will need t o sp ecify Initial Tem- perature and Specific H eat for a par ticle ma terial in the Create/M odify Injec tion dialo g box. Note The par ticle time st ep should b e chosen so tha t macr oscopic par ticles do not cr oss mor e than one CFD mesh c ell. 25.4.2. Specifying the D rag L aw Under the Drag tab , you c an selec t an appr opriate dr ag la w for y our simula tion and set the r elevant paramet ers or selec t Disable D rag C alcula tions if y ou do not w ant to mo del the dr ag f orce in the domain. Figur e 25.2: Macroscopic P article M odel D ialo g Box (D rag Tab) In the ANSY S Fluen t MPM mo del, the f ollowing f ormula tions ar e available f or mo deling the dr ag f orces between the c ontinuous and macr oscopic par ticle phases: •Momen tum D eficit R ate (MDR) (default) In this f ormula tion, the momen tum e xchange c oefficien t between fluid and solid phases is c al- cula ted as: wher e is the dr ag func tion, and is the macr oscopic par ticle time st ep. 2075Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling M acroscopic P articlesThe accur acy of the implicit c alcula tions using the M omen tum D eficit R ate mo del dep ends on numb er of c ells c ompr ising the macr oscopic par ticle .This dr ag c orrelation is mor e suitable f or bigger size par ticles . •Morsi-A lexander (MA) In the M orsi-A lexander based dr ag c orrelation 400 adopt ed in ANSY S Fluen t, the R eynolds numb er for the fluid phase is c alcula ted b y: wher e, = fluid densit y = fluid visc osity = par ticle diamet er = relative velocity of the discr ete and fluid phases The M orsi-A lexander based dr ag c orrelation is suitable f or smaller siz e par ticles . •Constan t Drag C oefficien t (Cd) This option implies tha t the dr ag is e valua ted using a c onstan t drag c oefficien t.This c orrelation is suitable f or c ases wher e the par ticle is mo ving a t a c ertain sp ecified v elocity (or acc eleration). •Size Based MA/MDR When this option is selec ted, the ANSY S Fluen t solv er aut oma tically swit ches b etween the M omen tum Deficit R ate and M orsi-A lexander dr ag la ws based on a cr itical diamet er.This dr ag f ormula tion is best suit ed f or c ases in volving wide r ange of par ticle siz es in a single simula tion. For par ticles with a diamet er b elow the v alue tha t you sp ecify f or Critical D iamet er, the M osi-A lexander dr ag la w will be used . Other wise , the M omen tum D eficit R ate formula tion will b e used . You c an define a dr ag fac tor in a sp ecific dir ection ( X-dir ,Y-dir ,Z-dir ). A dr ag fac tor of 1 means tha t the vir tual mass f orce equaliz es the momen tum diff erence of fluid in c ells t ouched b y the par ticle surface within a single flo w time st ep. As a c onsequenc e, the par ticle sub-time st ep has t o be much smaller (ab out one-f ourth) than the momen tum r elaxa tion time 427: wher e and are the par ticle and fluid densities , respectively, is the par ticle diamet er, and is the fluid visc osity. Besides , the accur acy of the pr edic ted dr ag dep ends on the numb er of c ells t ouched b y the par ticle . At least 20-30 c ells ar e requir ed acr oss the par ticle diamet er. For multiphase flo ws, you c an selec t an appr opriate fluid v elocity field t o be used in the dr ag f orce calcula tions .The f ollowing options ar e available in the Multiphase: Drag B ased On group b ox: •Primar y Phase Velocity Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2076Modeling M acroscopic P articles•Secondar y Phase Velocity •Volume-W eigh ted M ixture Velocity 25.4.3. Defining P aramet ers f or P article-P article and P article-W all C ollisions The Collision tab allo ws you t o mo del the eff ects of par ticle-par ticle and par ticle-w all c ollisions . Figur e 25.3: Macroscopic P article M odel D ialo g Box (C ollision Tab) To acc oun t for c ollisions b etween par ticles: 1.Selec t Enable P article-P article C ollision . 2.Specify the f ollowing par amet ers: Coefficien t of Restitution (N ormal D ir) corresponds t o in Equa tion 17.6 . Coefficien t of Restitution ( Tangen tial D ir) corresponds t o in Equa tion 17.7 . Subst eps F or C ollision is a numb er of sub-time st eps f or det ecting par ticle c ollision in each par ticle tr acking time st ep. Coefficien t of F riction corresponds t o in Equa tion 17.8 . If you also w ant to acc oun t for c ollisions b etween par ticles and w alls: 2077Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling M acroscopic P articles1.Selec t Enable P article-W all C ollision . 2.From the Participa ting Z ones F or C ollision selec tion list , selec t the appr opriate walls. 3.In addition t o Coefficien t of Restitution (N ormal D ir) and Coefficien t of Restitution ( Tangen tial D ir) on the selec ted w alls, you c an sp ecify the f ollowing par amet ers: Coefficien t of F riction (S liding) corresponds t o in Equa tion 17.8 . Coefficien t of F riction (Rolling) The v alue f or the r olling c oefficien t of fr iction will b e fac tored in the fr iction c oefficien t . 25.4.4. Specifying D eposition P aramet ers You c an use the Deposition tab t o sp ecify par amet ers f or macr oscopic par ticle dep osition and buildup on selec ted z ones . Figur e 25.4: Macroscopic P article M odel D ialo g Box (D eposition Tab) 1.Selec t Enable P article-W all D eposition . 2.From the Zones f or D eposition selec tion list , selec t the w all z ones on which the macr oscopic par ticles will adher e up on c ollision. 3.Specify the f ollowing dep osition par amet ers: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2078Modeling M acroscopic P articlesMinimum D rag F orce for P article D etachmen t specifies the f orce at or ab ove which the dep osited par ticles detach fr om a sur face zone . Max N ormal Velocity for P article D eposition ,Max Tangen tial Velocity for P article D eposition specify the nor mal and tangen tial c omp onen ts of the appr oach v elocity at or b elow which the par ticles dep osit on the sur face. 4.If you w ant to sa ve par ticle dep osition hist ory da ta in ASCII f ormat, enable Write Particle D eposition File. 5.To acc oun t for par ticle agglomer ation, selec t Enable P article-P article D eposition . A par ticle tha t collides with an y pr eviously dep osited par ticles will a ttach t o the par ticle sur face.The dep osition par amet ers tha t you ha ve sp ecified f or par ticle-w all dep osition will b e also used f or mo deling par ticle-par ticle dep osition. 25.4.5. Specifying Injec tion P aramet ers You c an use the Injec tions tab t o cr eate, edit , copy or delet e macr oscopic par ticle injec tions .You c an also sa ve all par ticle injec tions tha t you ha ve created t o a file f or la ter use or r ead injec tions fr om a previously gener ated file .The c ontrols under the Injec tion tab ar e similar t o those f ound in the Injec- tions dialo g box (see Injec tions D ialog Box in the Fluent U ser's G uide (p.3837 )) with a f ew minor diff er- ences. Figur e 25.5: Macroscopic P article M odel D ialo g Box (Injec tion Tab) The pr ocedur es for cr eating , mo difying and in teracting with injec tions ar e also similar t o those f or the DPM injec tions .The diff erences related t o the MPM injec tions will b e fur ther emphasiz ed. For mor e information ab out using these c ontrols, see the Fluen t User’s Guide . 2079Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling M acroscopic P articles•To create an MPM injec tion: click Create... and set the injec tion pr operties using the Create/M odify Injec tion dialo g box (see Defining MPM Injec tion P roperties (p.2080 )). After the injec tion is cr eated, it will app ear in the Injec tions selec tion list , in the Macroscopic P article M odel dialo g box. •To edit an e xisting MPM injec tion: selec t it fr om the Injec tions selec tion list , click Edit..., and in the Cre- ate/M odify Injec tion dialo g box tha t will op en, mo dify the injec tion pr operties as nec essar y . •To copy an e xisting MPM injec tion t o a new injec tion: selec t it fr om the Injec tions selec tion list and click Copy.The name of the new c opied injec tion app ended with _d will app ear in the Injec tions list. •To delet e an e xisting MPM injec tion: selec t it fr om the Injec tions selec tion list and click Delet e. •To wr ite inf ormation ab out all injec tions cr eated in a c ase: click Write All Injec tions ... and in the Selec t File dialo g box tha t will op en, enter the name f or the injec tion file . Note Write All Injec tions ... is not supp orted f or st eady flo ws with c emen ted par ticles . •To read pr eviously gener ated injec tion file in to your c ase: click Read ... and in the Selec t File dialo g box that will op en, selec t the injec tion file t o read in. If the injec tion with the same name alr eady exists in y our current case, then ANSY S Fluen t will r ename the imp orted injec tion b y app ending _d to the name . 25.4.5.1. Defining MPM Injec tion P roperties You c an define the pr operties of an MPM injec tion using the Create/M odify Injec tion dialo g box that can b e acc essed b y click ing Create....The pr ocedur e for defining a par ticle injec tion is as f ollows: 1.(Optional) C hange the default name of the injec tion (injection- id ) by en tering a new name in the Injec tion N ame entry field . 2.From the Injec tion Type drop-do wn list , selec t the injec tion t ype. In the ANSY S Fluen t MPM mo del, you can cr eate the f ollowing t ypes of injec tions: •point : defines an injec tion r eleased fr om a single p oint. •plane : defines unif ormly or r andomly distr ibut ed injec tions r eleased fr om a plane . •packing : defines an injec tion of par ticles pack ed in a b ox or c ylinder . •from-file : allo ws you t o read a t ext file tha t defines an injec tion. 3.If you w ant to mo del fix ed par ticles , enable Cemen ted P article(s) . Imp ortant For st eady-sta te simula tions , all par ticles must b e cemen ted. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2080Modeling M acroscopic P articles4.Specify the par ticle ph ysical par amet ers ( Diamet er and Densit y). Note Note tha t a ma terial defined in ANSY S Fluen t cannot b e assigned t o a par ticle . 5.Specify the injec tion t ype-sp ecific settings as descr ibed in the f ollowing sec tions: •point injec tions: Inputs f or point Injec tions (p.2082 ) •plane injec tions: Inputs f or plane Injec tions (p.2084 ) •packing injec tions: Inputs f or packing Injec tions (p.2086 ) •from-file injec tions: Inputs f or from-file Injec tions (p.2087 ) 6.(Optional) I f you w ant to mo del a c ontinuous gener ation of par ticle injec tions , selec t Enable C ontinuous Injec tion and in the Define C ontinuous Injec tion dialo g box tha t op ens when y ou click Set..., specify the r elevant par amet ers. You c an sp ecify the f ollowing settings: •Injec tion star t, stop, and in terval times New macr oscopic par ticle will b e injec ted in to the domain a t regular time in tervals sp ecified in Injec tion In terval Time from the Injec tion S tart Time to the Injec tion S top Time . •(Optional) M oving and/or r otating injec tion r elease p oint par amet ers (a vailable when Moving Injec tion is enabled): 2081Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling M acroscopic P articles–The or igin ( X,Y,Z) and the dir ection of the axis ( X,Y, or Z) about which the injec tion is r otating –The Angular Velocity of the injec tion lo cation –The X,Y,Z comp onen ts of the Transla tional Velocity of the injec tion lo cation At each time st ep, the MPM solv er det ermines a new p osition of a par ticle injec tion based on the injec tion or igin a t the pr evious time st ep and the sp ecified tr ansla tional v elocities . 7.Click Create/M odify . The new injec tion tha t you ha ve created app ears under the Injec tions selec tion list. 25.4.5.2. Inputs for point Injec tions For a p oint injec tion of a macr oscopic par ticle , you need t o define the f ollowing initial c onditions in the Create/M odify Injec tion dialo g box: •Particle diamet er •Particle densit y •Specific hea t of the par ticle ma terial (only f or hea t transf er simula tions) •Initial par ticle t emp erature (only f or hea t transf er simula tions) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2082Modeling M acroscopic P articles•Initial par ticle r elease lo cation: –Cartesian c oordina tes:X,Y, and Z –Cylindr ical coordina tes:Radius ,Angle , and Axial •Particle initial v elocity: –Cartesian c oordina tes:X,Y, and Z –Cylindr ical coordina tes:Radial ,Tangen tial, and Axial •Particle initial angular v elocity Cylindric al C oordinat e System By default , the global C artesian c oordina te sy stem is used . If you w ant to sp ecify injec tion par amet ers in a lo cal cylindr ical coordina te sy stem, enable the Cylindr ical C oordina tes option, and then define the lo cation of its or igin ( X,Y,Z) and Axis D irection . 2083Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling M acroscopic P articles25.4.5.3. Inputs for plane Injec tions To define macr oscopic par ticle injec tions r eleased fr om a plane: 1.Specify the par ticle initial c onditions as descr ibed in Inputs f or point Injec tions (p.2082 ), except f or the particle r elease lo cation. Note tha t for plane injec tions , velocities and initial p osition c an b e sp ecified only in C artesian c oordina tes. 2.Define the macr oscopic par ticle injec tion plane . Two options ar e available: •Rec tangular Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2084Modeling M acroscopic P articlesMacroscopic par ticles will b e injec ted fr om a r ectangular plane sur face tha t is off set fr om a c o- ordina te plane b y a distanc e sp ecified in X,Y, or Z Position in the selec ted X,Y, or Z axis dir- ection. The minimum and maximum limits of the r ectangular sur face ar e defined under the Extents of Rec tangular P lane group b ox. •Circular Macroscopic par ticles will b e injec ted fr om a cir cular plane sur face tha t is p erpendicular t o a selec ted c oordina te dir ection ( X,Y, or Z).The or igin and r adius of the cir cle ar e sp ecified under the Center L ocation/R adius of C ircular P lane group b ox. 3.Define the distr ibution of the par ticle r elease lo cations . Two mo deling options ar e available: •Random The MPM mo del will injec t par ticles in to a flo w domain fr om r andom lo cations on the injec tion plane .The t otal numb er of the r eleased par ticles is sp ecified in the Total # of P articles integer entry field . •Uniform The par ticles will b e injec ted in to a flo w domain fr om p oints ar ranged in a r ectangular pa ttern. The numb er of the r elease p oints in t wo axial dir ections is sp ecified in the appr opriate in teger entry fields (f or e xample ,# of P articles in X-dir and # of P articles in Y-dir ). 2085Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling M acroscopic P articles25.4.5.4. Inputs for packing Injec tions To define an injec tion of macr oscopic par ticles pack ed in a b ox or c ylinder : 1.Specify par ticle initial c onditions as descr ibed in Inputs f or point Injec tions (p.2082 ), except f or the particle r elease lo cation. Note tha t for plane injec tions , velocities and initial p osition c an b e sp ecified only in C artesian c oordina tes. 2.Define the pack ing r egion. For a Box-type pack ing, specify the minimum and maximum X, Y, and Z c oordina tes for the pack ing b ounding b ox under the Box Extents group b ox. For a Cylinder -type pack ing, specify the b ounding c ylinder axis , minimum and maximum c oordin- ates for the c ylinder heigh t, cylinder or igin and inner and out diamet ers. 3.Define the par ticle distr ibution in the pack ing. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2086Modeling M acroscopic P articlesTwo mo deling options ar e available: •Random The initial v olume fr action of par ticles in the pack ing is sp ecified in the Particle VOF entry field . •Uniform The distanc e between par ticles in the initial spa tially unif orm pack ing is sp ecified in the Inter Particle G ap entry field . 4.If you w ant to allo w a par t of the par ticle t o be outside of the domain (with the par ticle c enter b eing in the domain), enable Allow P artial P articles in the D omain . 25.4.5.5. Inputs for from-file Injec tions For injec tions tha t you w ant to sp ecify using the from-file option, the file f ormat is: number-of-particles diameter density x-pos y-pos z-pos x-vel y-vel z-vel x-rot y-rot z-rot pstart pstop pinterval cemented ... wher e the first line sp ecifies the numb er of par ticles (number-of-particles ), followed b y number- of-particles lines tha t define par amet ers f or the injec tion par ticles . For each par ticle , you must specify the diamet er, densit y, initial p osition, linear and angular v elocities , star t, end , and in terval times , and the in teger flag (cemented in the ab ove file f ormat sp ecific ation) indic ating whether or not the par ticle is mo ving . Note tha t cemented =1 indic ates a sta tionar y par ticle , while cemented =0 indic ates a mo ving par ticle .Values descr ibing an injec tion should b e separ ated b y one or mor e spac es and c an b e sp ecified using scien tific nota tion (e or E) if needed . All quan tities ar e in SI units . An example is sho wn b elow: 1 5e-2 5.08e-2 -1e-8 1e-7 2.4e-1 -2e-4 1e-5 1.1 0.0 0.0 0.0 0.0 1e-2 1e-4 0 25.4.6. Defining F ield F orces The Attraction F orces tab allo ws you t o include a ttraction f orces b etween par ticles and w alls in y our problem. 2087Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling M acroscopic P articlesFigur e 25.6: Macroscopic P article M odel D ialo g Box (A ttraction F orces Tab) To define the a ttraction f orces b etween macr oscopic par ticles: 1.Selec t Enable P article-P article F orces. 2.Specify the mo del c onstan ts n1,n2,n3, and G_p used in Equa tion 17.9 . To define the a ttraction f orces b etween macr oscopic par ticles and w alls: 1.Selec t Enable P article-W all F orces. 2.From the Participa ting Z ones selec tion list , selec t the appr opriate zones 3.Specify the mo del c onstan ts n4,n5, and G_w used in Equa tion 17.10 . 25.4.7. Initializing the MPM mo del The Initializ e MPM tab allo ws you t o apply macr oscopic par ticle r elated sour ce terms t o the c ontinuous phase , initializ e macr oscopic par ticles , and displa y par ticle tr ajec tories. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2088Modeling M acroscopic P articlesFigur e 25.7: Macroscopic P article M odel D ialo g Box (Initializ e MPM Tab) You c an also enable the f ollowing solution-r elated options: •Saving par ticle da ta in a F ield View and/or ASCII f ormat •Printing w arning messages r elated t o par ticle tr acking in the F luen t console Onc e you ha ve set up the MPM mo del, you need t o perform the f ollowing st eps: 1.Click Initializ e MPM F unc tions . This will set up macr oscopic par ticle r elated sour ce terms and apply them t o the c ontinuous phase . It will also ho ok all appr opriate UDF func tions t o the F luen t solv er. Initializing MPM func tions adds the f ollowing t wo commands t o the solv er tha t will b e execut ed during simula tion: •mpm1 : displa ys the par ticle p osition(s) a t each it eration st ep. •mpm3 : writes the par ticle p osition(s) a t each it eration st ep in PNG format. You c an disable these c ommands or mo dify the r eporting fr equenc y in the Execut e Command dialo g box (acc essible fr om the Solution/C alcula tion A ctivities/E xecut e Commands tree it em). If you w ant the solv er to report or monit or additional solution quan tities dur ing c alcula tion, you can define y our o wn e xecut e command(s) using F luen t TUI c ommands . For mor e inf ormation, see Executing C ommands D uring the C alcula tion in the Fluent U ser's G uide (p.2660 ). For c oupled simula tions , onc e you click Initializ e MPM F unc tions , the pr essur e discr etiza tion scheme will aut oma tically swit ch t o PREST O! to pr ovide a mor e robust solution. 2089Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling M acroscopic P articles2.Initializ e either the macr oscopic par ticles b y click ing Initializ e Particles or the flo w field in the usual w ay The macr oscopic par ticle(s) will b e in troduced in to the fluid flo w dur ing the ne xt computa tional time st ep. 3.Run the simula tion with the injec ted macr oscopic par ticle(s). Upon c ompletion of the MPM simula tion, you c an click Displa y Injec tions ... and use the Displa y Particles dialo g box to displa y the c omput ed par ticle tr ajec tories. In the Displa y Particles dialo g box, you c an selec t the par ticle c olor ing option. You c an c olor par ticle by the f ollowing par ticle v ariable v alues: •diamet er •mass •particle ID •velocity magnitude For the Particle Velocity M agnitude option, you c an sp ecify the minimum and maximum r ange of the v elocity magnitude v alues . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2090Modeling M acroscopic P articlesChapt er 26: Modeling M ultiphase F lows This chapt er discusses the gener al multiphase mo dels tha t are available in ANSY S Fluen t. For inf ormation about the v arious theor ies b ehind the gener al multiphase mo dels in ANSY S Fluen t, see Multiphase Flows in the Theor y Guide . Information ab out using the gener al multiphase mo dels in ANSY S Fluen t is presen ted in the f ollowing sec tions: 26.1. Introduc tion The first st ep in solving an y multiphase pr oblem is t o det ermine which of the r egimes descr ibed in Multiphase F low Regimes in the Theor y Guide best r epresen ts your flo w.Model C ompar isons in the Theor y Guide provides some br oad guidelines f or det ermining appr opriate mo dels f or each r egime , and Detailed G uidelines provides details ab out ho w to det ermine the degr ee of in terphase c oupling for flo ws involving bubbles , droplets , or par ticles , and the appr opriate mo del f or diff erent amoun ts of coupling . The f ollowing sec tions will guide y ou thr ough the setup , solution, and p ostpr ocessing of multiphase flow mo dels . 26.2. Steps f or U sing a M ultiphase M odel The pr ocedur e for setting up and solving a gener al multiphase pr oblem is outlined b elow, and descr ibed in detail in the subsec tions tha t follow. Rememb er tha t only the st eps tha t are pertinen t to gener al multiphase c alcula tions ar e sho wn her e. For inf ormation ab out inputs r elated t o other mo dels tha t you are using in c onjunc tion with the multiphase mo del, see the appr opriate sec tions f or those mo dels . See also Additional G uidelines f or E uler ian M ultiphase S imula tions (p.2208 ) for guidelines on simplifying Euler ian multiphase simula tions . Imp ortant Double P recision is recommended f or all multiphase c ases . 1.Enable the multiphase mo del y ou w ant to use ( VOF, mix ture, or E uler ian) and sp ecify the numb er of phases . For the VOF and E uler ian mo dels , specify the v olume fr action scheme as w ell. Setup → Models → Multiphase → Edit... See Enabling the M ultiphase M odel (p.2093 ) and Choosing Volume F raction F ormula tion (p.2097 ) for details . 2.Copy the ma terial represen ting each phase fr om the ma terials da tabase . Setup → Materials 2091Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.If the ma terial y ou w ant to use is not in the da tabase , create a new ma terial. See Using the Cre- ate/Edit M aterials Dialog Box (p.1081 ) for details ab out c opying fr om the da tabase and cr eating new materials. See Modeling C ompr essible F lows (p.2102 ) for additional inf ormation ab out sp ecifying material pr operties f or a c ompr essible phase . It is p ossible t o tur n off r eactions in some ma terials by selec ting none in the Reac tions drop-do wn list under Properties in the Create/Edit M aterials dialo g box. Imp ortant If your mo del includes a par ticula te (gr anular) phase , you will need t o cr eate a new ma- terial for it in the fluid ma terials c ategor y (not the solid ma terials c ategor y). 3.Define the phases , and sp ecify an y interaction b etween them (f or e xample , surface tension if y ou ar e using the VOF mo del, slip v elocity func tions if y ou ar e using the mix ture mo del, or dr ag func tions if y ou ar e using the E uler ian mo del). Setup → Models → Multiphase → Phases Edit... See Defining the P hases (p.2103 ) – Defining the P hases f or the E uler ian M odel (p.2209 ) for details . 4.(Euler ian mo del only) I f the flo w is turbulen t, define the multiphase turbulenc e mo del. Setup → Models → Visc ous → Edit... See Modeling Turbulenc e (p.2229 ) for details . 5.If body forces ar e pr esen t, enable gr avity and sp ecify the gr avitational acc eleration. Setup → Cell Z one C onditions → Operating C onditions ... See Including B ody Forces (p.2104 ) for details . 6.Specify the b oundar y conditions , including the sec ondar y-phase v olume fr actions a t flo w boundar ies and (if you ar e mo deling w all adhesion in a VOF simula tion) the c ontact angles a t walls. Setup → Boundar y Conditions See Defining M ultiphase C ell Z one and B oundar y Conditions (p.2124 ) for details . 7.Set an y mo del-sp ecific solution par amet ers. Solution → Metho ds Solution → Controls See Setting Time-D ependen t Paramet ers f or the Explicit Volume F raction F ormula tion (p.2179 ) and Solution S trategies f or M ultiphase M odeling (p.2261 ) for details . 8.Initializ e the solution and set the initial v olume fr actions f or the sec ondar y phases . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2092Modeling M ultiphase F lowsSolution → Initializa tion Patch... See Setting Initial Volume F ractions (p.2141 ) for details . 9.Calcula te a solution and e xamine the r esults . Postpr ocessing and r eporting of r esults ar e available f or each phase tha t is selec ted. See Solution S trategies f or M ultiphase M odeling (p.2261 ) and Postpr ocessing f or M ultiphase M odel- ing (p.2278 ) for details . Note •For inf ormation on multiphase mo del c ompa tibilit y with other F luen t mo dels , see Appendix A: AN- SYS Fluen t Model C ompa tibilit y (p.3965 ). •If the multiphase mo del is used in c ombina tion with a sp ecies mo del, the mass fr action of a species ma y be displa yed inc orrectly in ANSY S CFD-P ost if the v olume fr action of a c ell is z ero. This applies f or all ANSY S Fluen t files wr itten pr ior t o release 2019 R3. For all multiphase , multi-sp ecies c ases cr eated in r elease 19.2 and b eyond , the mass fr actions of sp ecies will not b e available in ANSY S CFD-P ost, unless y ou add the mass fr action of a species as an additional quan tity to be sa ved in the da ta file (thr ough the Data F ile Quan tities dialo g box). This sec tion pr ovides instr uctions and guidelines f or using the VOF, mix ture, and E uler ian multiphase models . Information is pr esen ted in the f ollowing subsec tions: 26.2.1. Enabling the M ultiphase M odel 26.2.2. Choosing Volume F raction F ormula tion 26.2.3. Solving a H omo geneous M ultiphase F low 26.2.4. The B oussinesq A pproxima tion in M ultiphase F low 26.2.5. Modeling C ompr essible F lows 26.2.6. Defining the P hases 26.2.7. Including B ody Forces 26.2.8. Modeling M ultiphase S pecies Transp ort 26.2.9. Specifying H eterogeneous R eactions 26.2.10. Including M ass Transf er Effects 26.2.11. Defining M ultiphase C ell Z one and B oundar y Conditions 26.2.12. Setting Initial Volume F ractions 26.2.1. Enabling the M ultiphase M odel To enable the VOF, mix ture, or E uler ian multiphase mo del, selec t Volume of F luid ,Mixture, or Euler ian under Model in the Multiphase M odel D ialog Box (p.3248 ). Setup → Models → Multiphase → Edit... The dialo g box will e xpand t o sho w the r elevant inputs f or the selec ted multiphase mo del. 2093Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Steps f or U sing a M ultiphase M odelVolume of F luid Mo del Inputs Figur e 26.1: Multiphase M odel D ialo g Box for the VOF M odel •Numb er of E uler ian P hases •(optional) Coupled L evel S et + VOF (see Coupled L evel-Set and VOF M odel in the Theor y Guide ) •volume fr action Formula tion (Explicit or Implicit ) and asso ciated par amet ers (see Choosing Volume Fraction F ormula tion (p.2097 )) •(optional) inclusion of sub-mo dels such as Open C hannel F low and Open C hannel Wave BC •Interface M odeling type and options (see Choosing Volume F raction F ormula tion (p.2097 )) •(optional) selec tion of Expert Options (see Expert Options (p.2100 )) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2094Modeling M ultiphase F lows•(optional) inclusion of the Implicit B ody Force formula tion (see Including B ody Forces (p.2104 )) Mixture Mo del Inputs Figur e 26.2: Multiphase M odel D ialo g Box for the M ixture M odel •Numb er of E uler ian P hases •(optional) inclusion of Slip Velocity (see Solving a H omo geneous M ultiphase F low (p.2101 )) •volume fr action Formula tion (Explicit or Implicit ) and asso ciated par amet ers (see Choosing Volume Fraction F ormula tion (p.2097 )) •Interface M odeling type and options (see Choosing Volume F raction F ormula tion (p.2097 )) •(optional) selec tion of Expert Options (see Expert Options (p.2100 )) •(optional) inclusion of the Implicit B ody Force formula tion (see Including B ody Forces (p.2104 )) 2095Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Steps f or U sing a M ultiphase M odelEulerian Mo del Inputs Figur e 26.3: Multiphase M odel D ialo g Box for the E uler ian M odel •Numb er of E uler ian P hases •(optional) inclusion of the Dense D iscr ete Phase M odel •(optional) inclusion of the Boiling M odel •(optional) inclusion of the Multi-F luid VOF M odel •volume fr action Formula tion (Explicit or Implicit ) and asso ciated par amet ers (see Choosing Volume Fraction F ormula tion (p.2097 )) •Interface M odeling type and options (see Choosing Volume F raction F ormula tion (p.2097 )).This is only available if the Multi-F luid VOF M odel is enabled . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2096Modeling M ultiphase F lows•(optional) selec tion of Expert Options (see Expert Options (p.2100 )) To sp ecify the numb er of phases f or the multiphase c alcula tion, enter the appr opriate value in the Numb er of E uler ian P hases field .You c an sp ecify up t o 20 phases . 26.2.2. Choosing Volume F raction F ormula tion ANSY S Fluen t supp orts the f ollowing options f or v olume fr action f ormula tion: Explicit F ormula tion The e xplicit f ormula tion is non-it erative and is time-dep enden t.Thus it c an only b e used with the Transien t solv er. It exhibits b etter numer ical accur acy compar ed t o the implicit f ormula tion. However the time st ep siz e is limit ed b y a C ourant-based stabilit y criterion. Implicit F ormula tion The implicit f ormula tion is it erative and c an b e used with either the Stead y or Transien t solv er. It is w ell-suit ed t o steady-sta te applic ations as the solution inf ormation pr opaga tes much fast er com- pared t o the e xplicit f ormula tion. For st eady-sta te flo w applic ations , either a st eady-sta te or a tr ansien t simula tion ma y be requir ed, de- pending on the char acteristics of the flo w: •Stead y-stat e simulation : If the final st eady-sta te solution is not aff ected b y the initial flo w conditions and ther e is a distinc t inflo w boundar y for each phase . •Transient simulation : If the final st eady-sta te solution is dep enden t on the initial flo w conditions and/or you do not ha ve a distinc t inflo w boundar y for each phase . For tr ansien t flo w applic ations , the implicit f ormula tion ma y allo w you t o use a much lar ger time st ep than the e xplicit f ormula tion due t o the implicit f ormula tion ’s unc onditional stabilit y. However, the implicit time-st ep siz e ma y be limit ed b y truncation er rors.The implicit f ormula tion pr oduces mor e numer ical diffusion than the e xplicit f ormula tion when using the First Or der transien t formula tion. Therefore, the implicit f ormula tion should b e used along with higher-or der tr ansien t formula tions t o achie ve better numer ical accur acy. To sp ecify the v olume fr action f ormula tion t o be used f or the VOF and E uler ian multiphase mo dels , selec t the appr opriate Formula tion under Volume F raction P aramet ers in the Multiphase M odel dialo g box. 26.2.2.1. Interface Mo deling Type For the VOF and M ixture multiphase mo dels and f or the E uler ian multiphase mo del with Multi-F luid VOF enabled , you must sp ecify the in terface regime tha t you will b e mo deling .This will det ermine the a vailabilit y of the v arious v olume fr action discr etiza tion schemes ( Spatial D iscretiza tion Schemes for Volume F raction (p.2099 )).The f ollowing options ar e available f or Interface M odeling Type: Sharp (VOF and M ulti-F luid VOF mo dels only) f or when a distinc t interface is pr esen t between the phases Dispersed for when the phases ar e interpenetr ating 2097Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Steps f or U sing a M ultiphase M odelSharp/D ispersed a hybrid appr oach f or flo ws consisting of b oth shar p and disp ersed in terfaces.This option c an also be used t o captur e mildly shar p in terfaces. Mildly shar p in terfaces ar e those tha t are neither as shar p as w ould b e captur ed b y the schemes a vailable with the Sharp option, nor as diffused as w ould b e captur ed b y the schemes a vailable with the Dispersed option. Interfacial A nti-D iffusion If you ar e using the S harp in terface mo deling t ype, you c an optionally enable the Interfacial A nti- Diffusion treatmen t.This tr eatmen t is applied only in in terfacial c ells and a ttempts t o suppr ess the numer ical diffusion tha t can ar ise fr om the v olume fr action ad vection schemes . The use of this tr eatmen t can ha ve ad verse eff ects on c onvergenc e, esp ecially with aggr essiv e settings and lar ge time st ep siz e.Therefore, it should b e used in c ases tha t use a c oarse mesh, tha t ha ve high aspect-ratio c ells, tha t ha ve lar ge c ell-v olume jumps in the vicinit y of the fluid-fluid in terface, or tha t suffer fr om e xcess numer ical diffusion. The str ength of the an ti-diffusion tr eatmen t can b e sp ecified using the define/models/mul- tiphase/interface-modeling-options text command .The str ength c an r ange b etween 0 (none) and 1 (maximum). Sharp/D ispersed Int erface Mo deling O ptions Selec ting Sharp/D ispersed will mak e available some additional discr etiza tion options .To acc ess these , click Interface M odeling Options ... in the Multiphase M odel dialo g box. These options allo w you t o adjust the discr etiza tion b ehavior on a p er-zone and/or p er-phase-pair basis f or c ases in which it is imp ortant to simultaneously mo del disp ersed and shar p in terfaces. Zonal D iscr etiza tion This option is appr opriate for applic ations tha t requir e either shar p or disp ersed in terface mo deling dep ending on the c ell z one . After enabling Zonal D iscr etiza tion you will need t o sp ecify the slop e limit er value on the Multiphase tab of the Fluid dialo g box for each c ell z one . (See Defining M ultiphase Cell Z one and B oundar y Conditions (p.2124 )) Phase L ocaliz ed D iscr etiza tion This option is appr opriate for applic ations tha t requir e either shar p or disp ersed in terface mo deling dep ending on the phase-pair c ompr ising the in terface. After enabling Phase L ocaliz ed D iscr etiza tion you will need t o sp ecify the slop e limit er values f or each phase pair on the Discr etiza tion tab of the Phase In teraction dialo g box. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2098Modeling M ultiphase F lows26.2.2.2. Spatial D iscr etization Schemes for Volume F raction You c an cho ose fr om v arious spa tial discr etiza tion schemes f or v olume fr action dep ending on the multiphase mo del in use , the in terface regime t ype, and the v olume fr action f ormula tion chosen. The available discr etiza tion schemes f or each c ombina tion of mo del, formula tion, and in terface regime are summar ized in the f ollowing tables: Table 26.1: Spatial D iscr etiza tion Schemes f or the VOF and E uler ian with M ulti-F luid VOF M odels Explicit F ormula tion Implicit F ormula tion Interface M odeling Type Geo-R econstr uct CICSAMCompr essiv e BGM (st eady sta te only) Modified HRICSharp Compr essiv e Modified HRIC Compr essiv e Modified HRICSharp/D ispersed First Or der U pwind QUICKFirst Or der U pwind Second Or der U pwind QUICKDispersed Table 26.2: Spatial D iscr etiza tion Schemes f or the E uler ian M odel without M ulti-F luid VOF Explicit F ormula tion Implicit F ormula tion First Or der U pwind QUICKFirst Or der U pwind QUICK Modified HRIC Modified HRIC Compr essiv e Table 26.3: Spatial D iscr etiza tion Schemes f or the M ixture M odel Explicit F ormula tion Implicit F ormula tion Interface M odeling Type Compr essiv e Modified HRICSharp/D ispersed First Or der U pwind QUICKDispersed The Geo-Rec onstr uct scheme is an in terface tracking scheme based on geometr ical inf ormation. It is the most accur ate scheme , but is mor e computa tionally e xpensiv e than the other schemes .Geo- Rec onstr uct is the pr eferred scheme when solving on meshes of p oor qualit y. The CICSAM ,Modified HRIC , and Compr essiv e schemes ar e in terface captur ing schemes based on algebr aic inf ormation. The D onor-A cceptor discr etiza tion is a scheme applic able only t o quad- and he x-meshes . As it is consider ed obsolet e, it do es not app ear b y default in the gr aphic al user in terface. However, it c an b e made a vailable if r equir ed using the f ollowing t ext command: 2099Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Steps f or U sing a M ultiphase M odel/solve/set/expert <...> Allow selection of all applicable discretization schemes? [no] yes This c ommand c an also b e used t o expose discr etiza tion schemes tha t ma y be applic able , but ar e hidden b y default acc ording t o the tables ab ove. Imp ortant For the geometr ic reconstr uction and donor-acc eptor schemes , if y ou ar e using a c onformal mesh (tha t is, if the mesh no de lo cations ar e iden tical at the b oundar ies wher e two sub do- mains meet), you must ensur e tha t ther e ar e no t wo-sided (z ero-thick ness) w alls within the domain. If ther e ar e, you will need t o slit them, as descr ibed in Slitting F ace Zones (p.812). For mor e details ab out the implemen tations of the v olume fr action discr etiza tion schemes , refer to Interpolation N ear the In terface in the Fluent Theor y Guide . 26.2.2.3. Volume F raction Limits The Volume F raction C utoff allo ws you t o sp ecify a cut off limit f or the v olume fr action v alues .The value tha t you pr ovide is used as the lo wer cut off f or the v olume fr action. All volume fr action v alues in the domain b elow this cut off v alue ar e set t o zero.The upp er cut off is c alcula ted as (1.0 - lo wer cutoff). All volume fr action v alues ab ove the upp er cut off v alue ar e set t o 1.0. The default v alue is 1e-6, which is the r ecommended v alue . Using a higher v alue ma y lead t o a higher v olume imbalanc e. Imp ortant The Volume F raction C utoff value c an b e sp ecified only with the Explicit formula tion for v olume fr action. Note For the Implicit formula tion, the minimum v alue allo wed is 0 and the maximum al- lowable v alue is 1e-6. For the Explicit formula tion, the minimum v alue allo wed is 0 and the maximum allo wable v alue is 1e-4. A higher cut off v alue is a vailable with the Explicit formula tion b ecause it allo ws for the lo cal redistr ibution pr ocedur e of par tially filled c ells, which acc oun ts for v olume loss .This tr eatmen t is not a vailable with the Implicit formula tion. 26.2.2.4. Expert Options When using the Explicit formula tion, ther e ar e se veral additional options tha t you c an acc ess b y click ing Expert Options ... in the Multiphase M odel dialo g box. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2100Modeling M ultiphase F lowsSub-T ime S tep C alcula tion M etho d This setting c ontrols ho w the time-sc ale is c omput ed when det ermining the time st ep used f or v olume fraction. Solve VOF E very Iteration This setting c ontrols whether t o solv e the v olume fr action equa tions onc e per it eration, or only onc e per time st ep. For a mor e detailed discussion of ho w to use these options , refer to Setting Time-D ependen t Para- met ers f or the Explicit Volume F raction F ormula tion (p.2179 ). 26.2.3. Solving a H omo geneous M ultiphase F low If you ar e using the mix ture mo del, you ha ve the option t o disable the c alcula tion of slip v elocities and solv e a homo geneous multiphase flo w (tha t is, one in which the phases all mo ve at the same v e- locity). By default , ANSY S Fluen t will c omput e the slip v elocities f or the sec ondar y phases , as descr ibed in Relative (Slip) Velocity and the D rift Velocity in the Theor y Guide . If you w ant to solv e a homo geneous multiphase flo w, turn off Slip Velocity under Mixture Paramet ers. 26.2.4. The B oussinesq A ppr oxima tion in M ultiphase F low When using the B oussinesq appr oxima tion f or densit y variation in multiphase flo ws, ther e ar e se veral imp ortant items t o consider : •The B oussinesq appr oxima tion is only v alid f or small v ariations in fluid densities c aused b y small v ariations in temp erature.Therefore, constan t densit y is assumed , and a momen tum sour ce is only added f or mo deling buo yancy. •The B oussinesq appr oxima tion assumes tha t small densit y variations ha ve little eff ect on iner tial t erms and strong eff ects on gr avitational t erms.Thus, the diff erences in sp ecific w eigh ts between t wo fluids or la yers of fluids is the f orce dr iving the flo w. (Waves c annot use this appr oxima tion.) Two non-dimensional numb ers quan tify the eff ect of buo yancy: the R ichar dson numb er and the R ayleigh numb er. •Operating densit y should b e set t o zero. For additional inf ormation on the B oussinesq appr oxima tion, see The B oussinesq M odel (p.1476 ). 2101Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Steps f or U sing a M ultiphase M odel26.2.5. Modeling C ompr essible F lows If you ar e using an y of the multiphase mo dels f or a c ompr essible flo w, not e the f ollowing: •ANSY S Fluen t allo ws the mo deling of : –Multiple c ompr essible ideal gas phases and/or inc ompr essible/c ompr essible liquids a t an y inlet –A single r eal gas or r eal liquid a t an y inlet –Multiple r eal gases a t a single inlet –Multiple c ompr essible liquids using either the F luen t built-in c ompr essible liquid densit y mo del based on the Tait la w (see Compr essible Liquid D ensit y Metho d (p.1100 )) or user-defined func tions For multiple c ompr essible phases , the fundamen tal equa tions f or c ompr essible flo w remain the same . However, boundar y conditions ar e mo dified t o acc oun t for changes in ma terial pr operties due t o compr essible fluid mix tures. •In cases of a mix ture of ideal and r eal gases , the phases must en ter the domain thr ough separ ate inlets . •When using the VOF mo del, stabilit y is impr oved if the pr imar y phase is the c ompr essible ideal gas . •If you sp ecify the t otal pr essur e at a b oundar y (for e xample , for a pr essur e inlet or in take fan), Fluen t will use the sp ecified v alue f or temp erature at tha t boundar y as t otal t emp erature for the c ompr essible phase , and as sta tic t emp erature for the other phases (which ar e inc ompr essible). •For each mass-flo w inlet , you will need t o sp ecify mass flo w or mass flux f or each individual phase . Imp ortant Note tha t if y ou r ead a c ase file tha t was set up in a v ersion of F luen t pr evious t o 6.1, you will need t o redefine the c onditions a t the mass-flo w inlets . See Defining M ultiphase Cell Z one and B oundar y Conditions (p.2124 ) for mor e inf ormation on defining c onditions for a mass-flo w inlet in multiphase c alcula tions . Enhanc ed C ompr essible F low Numerics Compr essible flo w simula tions ma y ha ve convergenc e difficulties due t o explicit handling of sour ce term acc oun ting f or densit y variation. These simula tions c ould b ecome e xtremely unstable in the presenc e of a lar ge v ariation in pr essur e and t emp erature. In ANSY S Fluen t, an enhanc ed numer ical treatmen t tha t provides b etter stabilit y at star tup and dur ing c alcula tion of c ompr essible flo ws is enabled by default. The tr eatmen t controls the r ate of change of pr essur e and t emp erature between it erations and pr ovides additional diagonal dominanc e to the ma trix of equa tions . Although disabling the enhanc ed numer ical tr eatmen t is not r ecommended , you c an t emp orarily tur n it off t o in vestiga te unstable c ases using the f ollowing t ext user in terface command: solve/set/multiphase-numerics/compressible-flow/enhanced-numerics ... enhanced compressible flow numerics? [yes] no See Compr essible F lows (p.1217 ) for mor e inf ormation ab out c ompr essible flo ws. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2102Modeling M ultiphase F lowsAlternativ e Compr essible F low Numerics A mor e gener al formula tion f or c ompr essible multiphase flo ws emplo ys a ma thema tically r igor ous treatmen t of c ompr essible phases a t an inlet b oundar y. Inst ead of tr eating the en tering inc ompr essible and c ompr essible phases as a pseudo-mix ture, this f ormula tion c alcula tes sta tic t emp erature and pressur e using an it erative metho d based on fundamen tal ther modynamic r elations (such as the Maxwell r elations). This appr oach in volves e valua tion of the pr operty der ivatives, which c an b e comput ed either numer ically or thr ough analytic e xpressions .You c an enable this alt ernative treatmen t via the text command: solve/set/multiphase-numerics/compressible-flow/alternate-bc-formulation alternate compressible bc formulation? [no] y use analytical thermodynamic derivatives? [no] y 26.2.6. Defining the P hases To define the phases (including their ma terial pr operties) and an y interphase in teraction (f or e xample , surface tension and w all adhesion f or the VOF mo del, slip v elocity for the mix ture mo del, drag func tions for the mix ture and the E uler ian mo dels), (Figur e 26.4: The P hases D ialog Box (p.2103 )). Setup → Models → Multiphase → Phases Edit... Figur e 26.4: The P hases D ialo g Box Each it em in the Phases list in this dialo g box is one of t wo types: a Primar y-Phase indic ates tha t the selec ted it em is the pr imar y phase , and Secondar y-Phase indic ates tha t the selec ted it em is a sec ondar y phase .To sp ecify an y interaction b etween the phases , click the Interaction... butt on. 2103Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Steps f or U sing a M ultiphase M odelInstr uctions f or defining the phases and in teraction ar e pr ovided in Defining the P hases f or the VOF Model (p.2171 ),Defining the P hases f or the M ixture M odel (p.2189 ), and Defining the P hases f or the E u- lerian M odel (p.2209 ) for the VOF, mix ture, and E uler ian mo dels , respectively. 26.2.7. Including B ody Forces When lar ge b ody forces (f or e xample , gravity or sur face tension f orces) e xist in multiphase flo ws, the body force and pr essur e gr adien t terms in the momen tum equa tion ar e almost in equilibr ium while the c ontributions of c onvective and visc ous t erms ar e small in c ompar ison. Segregated algor ithms converge p oorly unless par tial equilibr ium of pr essur e gr adien t and b ody forces is tak en in to acc oun t. ANSY S Fluen t provides an optional “implicit b ody force” treatmen t tha t can acc oun t for this eff ect, mak ing the solution mor e robust. The basic pr ocedur e involves augmen ting the c orrection equa tion f or the fac e flo w rate,Equa tion 28.56 in the Theor y Guide , with an additional t erm in volving c orrections t o the b ody force.This r esults in extra body force correction t erms in Equa tion 28.54 in the Theor y Guide , and allo ws the flo w to achie ve a realistic pr essur e field v ery ear ly in the it erative pr ocess. To include this b ody force, enable Gravity in the Operating C onditions D ialog Box (p.3470 ) and sp ecify the Gravita tional A cceler ation . Setup → Cell Z one C onditions → Operating C onditions ... For VOF c alcula tions , you should also enable the Specified Op erating D ensit y option in the Operating Conditions dialo g box, and set the Operating D ensit y to be the densit y of the ligh test phase . (This excludes the buildup of h ydrosta tic pr essur e within the ligh test phase , impr oving the r ound-off accur acy for the momen tum balanc e.) If an y of the phases is c ompr essible , set the Operating D ensit y to zero. Imp ortant For VOF and mix ture calcula tions in volving b ody forces, it is r ecommended tha t you also enable the Implicit B ody Force treatmen t for the Body Force Formula tion in the Mul- tiphase M odel dialo g box.This tr eatmen t impr oves solution c onvergenc e by acc oun ting for the par tial equilibr ium of the pr essur e gr adien t and b ody forces in the momen tum equa tions . See Including B ody Forces (p.2104 ) for details . 26.2.8. Modeling M ultiphase S pecies Transp ort ANSY S Fluen t lets y ou descr ibe a multiphase sp ecies tr ansp ort and v olumetr ic reaction ( Modeling Species Transp ort in M ultiphase F lows in the Theor y Guide ) in a fashion tha t is similar t o setting up a single-phase chemic al reaction using the Species M odel dialo g box (for e xample ,Figur e 26.5: The Species M odel D ialog Box with a M ultiphase M odel Enabled (p.2105 )). Setup → Models → Species → Edit... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2104Modeling M ultiphase F lowsFigur e 26.5: The S pecies M odel D ialo g Box with a M ultiphase M odel E nabled 1.Selec t Species Transp ort under Model. 2.Enable Volumetr ic under Reac tions . 3.Selec t a sp ecific phase using the Phase drop-do wn list under Phase P roperties . 4.Click the Set... butt on t o displa y the Phase P roperties dialo g box (Figur e 26.6: The P hase P roperties Dialog Box (p.2106 )). 2105Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Steps f or U sing a M ultiphase M odelFigur e 26.6: The P hase P roperties D ialo g Box In the Phase P roperties dialo g box, the ma terial for each phase is list ed in the Material drop-do wn list. From this list , you c an cho ose the ma terial tha t you w ant to use f or a sp ecific phase .The dr op- down list c ontains all of the ma terials, then op en the Edit M aterial dialo g box by click ing the Edit... (or View...) butt on ne xt to the Material drop-do wn list. 5.In the Species M odel dialo g box, cho ose the Turbulenc e-Chemistr y In teraction mo del. Three mo dels are available: Finit e-Rate/N o TCI comput es only the A rrhenius r ate (see Equa tion 7.7 in the Theor y Guide ) and neglec ts turbulenc e- chemistr y interaction. Eddy-D issipa tion (for turbulen t flo ws) comput es only the mixing r ate (see Equa tion 7.25 and Equa tion 7.26 in the Theor y Guide ). Finit e-Rate/Eddy-D issipa tion (for turbulen t flo ws) comput es b oth the A rrhenius r ate and the mixing r ate and uses the smaller of the t wo. When mo deling multiphase sp ecies tr ansp ort, additional inputs ma y also b e requir ed dep ending on your mo deling needs . See, for e xample ,Specifying H eterogeneous R eactions (p.2106 ) for mor e inf orm- ation defining het erogeneous r eactions , or Including M ass Transf er E ffects (p.2109 ) for mor e inf ormation on mass tr ansf er eff ects. 26.2.9. Specifying H eterogeneous Reac tions You c an use ANSY S Fluen t to define multiple het erogeneous r eactions and st oichiometr y using the Phase In teraction dialo g box (for e xample ,Figur e 26.7: The P hase In teraction D ialog Box for H etero- geneous R eactions (p.2107 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2106Modeling M ultiphase F lowsSetup → Models → Multiphase → Phases Edit... → Interaction... 1.In the Phases dialo g box (Figur e 26.4: The P hases D ialog Box (p.2103 )), click the Interaction... butt on t o open the Phase In teraction dialo g box. Figur e 26.7: The P hase In teraction D ialo g Box for H eterogeneous Reac tions 2.Click the Reac tions tab in the Phase In teraction dialo g box. 3.Set the t otal numb er of r eactions (v olumetr ic reactions , wall sur face reactions , and par ticle sur face reactions) in the Total N umb er of H eterogeneous Reac tions field . (Use the ar rows to change the v alue , or t ype in the v alue and pr ess Enter.) 4.Enable the Heterogeneous S tiff C hemistr y Solver option if y our in ter-phase r eaction mechanism c ontains numer ically stiff r eactions .This option c an impr ove convergenc e and is a vailable f or tr ansien t Euler ian multiphase simula tions .When this option is enabled , ANSY S Fluen t uses a fr actional st ep algor ithm wher e the flo w is ad vanced without r eaction sour ces for a time st ep, and then the chemistr y is in tegrated p oint- by-point for the same time st ep.The stiff chemistr y scheme solv es all sp ecies in all phases c oupled . Note that it is p ossible t o include homo geneous (in tra-phase) r eactions along with the het erogeneous r eactions in the (Phase In teraction dialo g box (inst ead of in the r eaction mechanism in the Create/Edit M aterials dialo g box), and these r eactions will b e solv ed with the stiff solv er.The stiff ODE solv er toler ances c an b e set using the f ollowing t ext command: solve → set → heterogeneous-stiff-chemistry 5.Specify the Reac tion N ame of each r eaction tha t you w ant to define . 6.Set the ID of each r eaction y ou w ant to define . (Again, if you t ype in the v alue b e sur e to pr ess Enter.) 2107Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Steps f or U sing a M ultiphase M odel7.For each r eaction, specify ho w man y reactants and pr oduc ts ar e involved in the r eaction b y incr easing the v alue of the Numb er of Reac tants and the Numb er of P roduc ts. Selec t each r eactant or pr oduc t in the Reac tion tab and then set its st oichiometr ic coefficien t in the Stoich. Coefficien t field . (The st oi- chiometr ic coefficien t is the c onstan t or in Equa tion 7.6 in the Theor y Guide .) 8.For each r eaction, indic ate the Phase and Species and the st oichiometr ic coefficien t for each of y our r e- actants and pr oduc ts. 9.For each r eaction, use the Reac tion R ate Func tion drop-do wn list t o selec t one of the f ollowing: none if you do not w ant to include a r eaction r ate popula tion-balanc e is the mass tr ansf er due t o nuclea tion and gr owth. If neither the pr imar y phase or sec ondar y phase has sp ecies asso ciated with it , then the mass tr ansf er is mo deled as unidir ectional. If the mass tr ansf er process in volves reactions or sp ecies , the pr oblem must b e set up as one in volving het erogeneous reaction/mass tr ansf er. Imp ortant The popula tion-balanc e option f or Reac tion R ate Func tion should not b e used if ther e ar e multiple r eactions leading t o the f ormation of the sec ondar y phase . In this case, the r eaction r ate func tions should b e sp ecified either thr ough the standar d dialo g boxes or user-defined func tions and the gr owth r ate func tion should b e a sum of the individual r eaction r ates.This w ould ensur e consist ency between the individual r eaction r ates and the t otal mass tr ansf er fr om the pr imar y to the sec ondar y phase . You c an alw ays use DEFINE_MASS_TRANSFER or DEFINE_HET_RXN_RATE user-defined func tion t ypes inst ead of the popula tion-balanc e option t o sp ecify mass tr ansf er rates. However, the gr owth r ate func tion and the mass tr ansf er rates retur ned fr om the UDFs need t o be con- sistent with each other . arrhenius-r ate to sp ecify r ate exponen ts for an A rrhenius-t ype reaction (see Heterogeneous P hase In teraction in the Theor y Guide for mor e inf ormation) Imp ortant This simple f orm of the A rrhenius r ate option ma y only b e used f or de volatiliza tion reactions only . Char c ombustion r eaction ma y be mor e involved and c omplic ated to be simply c asted in this f orm. Additional diffusion r ate formula tions ma y be needed to formula te a c omplet e char (or solid phase) r eaction sy stem. Imp ortant Note tha t you c an also sp ecify the het erogeneous r eaction r ates using a user-defined func tion. A user-defined func tion is a vailable f or an A rrhenius-t ype reaction with r ate Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2108Modeling M ultiphase F lowsexponen ts tha t are equiv alen t to the st oichiometr ic coefficien ts. For mor e inf ormation, see DEFINE_HET_RXN_RATE in the Fluen t Customiza tion M anual . Imp ortant ANSY S Fluen t assumes tha t the r eactants ar e mix ed thor oughly before reacting t ogether , ther efore the hea t and momen tum tr ansf er is based on this assumption. This assumption can b e disabled using a t ext command . For mor e inf ormation, contact your ANSY S Fluen t sup- port engineer . 26.2.10. Including M ass Transf er E ffects As discussed in Modeling M ass Transf er in M ultiphase F lows in the Theor y Guide , mass tr ansf er eff ects in the fr amew ork of ANSY S Fluen t’s gener al multiphase mo dels (tha t is, Euler ian multiphase , mix ture multiphase , or VOF multiphase) c an b e mo deled in one of thr ee w ays: •Unidir ectional c onstan t rate mass tr ansf er •UDF-pr escr ibed mass tr ansf er •mass tr ansf er thr ough c avitation, evaporation-c ondensa tion, boiling , or gener alized sp ecies mass tr ansf er Because of the diff erent procedur es and limita tions in volved, defining mass tr ansf er thr ough the Singhal et al. cavitation mo del is descr ibed separ ately in Including C avitation E ffects (p.2199 ). Note There ar e limita tions and r ecommenda tions sp ecific t o using c avitation with the VOF mo del. See Limita tions of C avitation with the VOF M odel in the Fluent Theor y Guide for additional information. For gener al limita tions r egar ding the c avitation mo dels , see Limita tions of the C avitation Models in the Fluent Theor y Guide . To define mass tr ansf er in a multiphase simula tion as a unidir ectional c onstan t, using a user-defined func tion, through p opula tion balanc e, cavitation, evaporation/c ondensa tion, or sp ecies mass tr ansf er you will need t o use the Phase In teraction dialo g box (for e xample ,Figur e 26.8: The P hase In teraction Dialog Box for M ass Transf er (p.2110 )). Setup → Models → Multiphase → Phases Edit... → Interaction... 2109Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Steps f or U sing a M ultiphase M odelFigur e 26.8: The P hase In teraction D ialo g Box for M ass Transf er 1.Click the Mass tab in the Phase In teraction dialo g box. 2.Specify the Numb er of M ass Transf er M echanisms . Imp ortant In gener al, you should use only one mass tr ansf er mechanism when y ou emplo y one of the a vailable mass tr ansf er mo dels (see S tep 7). Although using multiple mass tr ansf er mechanisms is allo wed f or an y pairs of phases (including the same pair of phases), it is not r ecommended b ecause the mass tr ansf er mo dels ha ve been fundamen tally de velop ed for a single mass tr ansf er pr ocess.These mo dels do not acc oun t for p ossible in teractions between t wo mass tr ansf er mechanisms in a flo w sy stem. In or der t o acc oun t for all relevant ph ysics using UDFs in multiple mass tr ansf er mechanisms , you c an use the user- defined option. For additional r estrictions when using multiple mass tr ansf er mechanisms , see S tep 7. 3.For each mechanism, specify the phase of the sour ce ma terial under From P hase . Note tha t the phase you selec t for From P hase must b e a liquid if y ou plan t o selec t cavita tion ,evaporation-c ondensa tion , or boiling from the Mechanism drop-do wn menu (see S tep 7). 4.If species tr ansp ort is par t of the simula tion, and the sour ce phase is c omp osed of a mix ture ma terial, then specify the sp ecies of the sour ce phase mix ture ma terial in the c orresponding Species drop-do wn list. 5.For each mechanism, specify the phase of the destina tion ma terial phase under To Phase . Note tha t the phase y ou selec t for To Phase must b e a v apor if y ou plan t o selec t cavita tion ,evaporation-c ondensa tion , or boiling from the Mechanism drop-do wn menu . If you plan t o selec t species-mass-tr ansf er and one of the phases is a gas , it must b e sp ecified as the To Phase (see S tep 7). 6.If species tr ansp ort is par t of the simula tion, and the destina tion phase is c omp osed of a mix ture ma terial, then sp ecify the sp ecies of the destina tion phase mix ture ma terial in the c orresponding Species drop- down list. 7.For each pair of phases with mass tr ansf er, selec t the desir ed mass tr ansf er mechanism under Mechanism . The a vailable mechanisms and their inputs ar e descr ibed in Mass Transf er M echanisms (p.2113 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2110Modeling M ultiphase F lowsANSY S Fluen t will aut oma tically include the t erms needed t o mo del mass tr ansf er in all r elevant conser vation equa tions . Another option t o mo del mass tr ansf er b etween phases is thr ough the use of user-defined sour ces and their inclusion in the r elevant conser vation equa tions .This appr oach is mor e involved, but mor e powerful, allo wing y ou t o split the sour ce terms acc ording t o a mo del of y our choic e. Imp ortant •Except f or the species-mass-tr ansf er mechanism, if the same mass tr ansf er mo del is selec ted for multiple mass tr ansf er mechanisms , the most r ecently edit ed mechanism sub-mo del, including its par amet ers, options , and c onstan ts (e xcluding its ma terial pr operties, such as v aporization pressur e or sa turation t emp erature), will apply t o all the mass tr ansf er mechanisms . •When mo deling multiple species-mass-tr ansf er mechanisms , you c an selec t diff erent species mass tr ansf er mo dels and mo del options , such as R aoult's La w, Henry's La w, etc. However, because ther e is a lack of in teraction b etween diff erent species mass tr ansf er mo dels , this should b e done with c aution. For inf ormation on mo deling r estrictions f or in terphase sp ecies mass tr ansf er, see Interphase S pecies M ass Transf er in the Fluent Theor y Guide . •Momen tum, ener gy, and turbulenc e are also tr ansp orted with the mass tha t is tr ansf erred. ANSY S Fluen t assumes tha t the r eactants ar e mix ed thor oughly before reacting t ogether , ther efore the heat and momen tum tr ansf er is based on this assumption. This assumption c an b e disabled using a t ext command . For mor e inf ormation, contact your ANSY S Fluen t supp ort engineer . When y our mo del in volves the tr ansp ort of multiphase sp ecies , you c an define a mass tr ansf er mech- anism b etween sp ecies fr om diff erent phases . If a par ticular phase do es not ha ve a sp ecies asso ciated with it , then the mass tr ansf er thr oughout the sy stem will b e performed b y the bulk fluid ma terial. Imp ortant Including sp ecies tr ansp ort eff ects in the mass tr ansp ort of multiphase simula tion r equir es that Species Transp ort be selec ted in the Species M odel dialo g box. Setup → Models → Species 26.2.10.1. Alternativ e Mo deling of E ner gy Sour ces The e xisting f ormula tion of sensible en thalp y for in terphase mass tr ansf er includes the f ormation enthalp y, which c ould b e pr oblema tic f or some c ases , such as c ases tha t involve sp ecies tr ansp ort and r eactions .The alt ernative treatmen t, which is a vailable with the VOF and M ixture multiphase models , is based on the e xplicit mo deling of the ener gy sour ce dr iven b y mass tr ansf er.You c an enable the alt ernative formula tion b y using the f ollowing t ext command: solve/set/multiphase-numerics/heat-mass-transfer/alternative-energy- treatment? enable alternative treatment of handling latent heat source [no] y 2111Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Steps f or U sing a M ultiphase M odelEner gy Sour ce Treatment The ener gy sour ce is mo deled e xplicitly as: (26.1) wher e is the mass tr ansf er rate, and is la tent hea t of v aporization. If you ar e using the tabular- ptl-sa t metho d to sp ecify sa turation t emp erature for the Evaporation-C ondensa tion M echanism (p.2118 ) or v aporization pr essur e for the Cavitation M echanism (p.2114 ), ANSY S Fluen t will tak e the la tent hea t values dir ectly fr om the tabular da ta. Other wise , it is c alcula ted as: (26.2) Here, and are sa turation en thalpies of phase and phase at the sa turation t emp erature, re- spectively.They are calcula ted as: (26.3) (26.4) wher e, and = formation en thalpies of phase and phase , respectively and = sp ecific hea ts of phase and phase , respectively and = reference temp eratures of phase and phase as sp ecified in the Create/Edit M aterials dialo g box, respectively. = sa turation t emp erature Note For mass tr ansf er mechanisms tha t do not r equir e explicit input of sa turation t emp erature, such as c avitation and sp ecies mass tr ansf er, the sa turation t emp erature is assumed as the reference temp erature of the liquid . Sensible E nthalp y Definition For mass tr ansf er cases , ANSY S Fluen t by default uses the f ollowing definition of sensible en thalp y: (26.5) wher e, = sensible en thalp y of phase = formation en thalp y of phase = sp ecific hea t of phase Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2112Modeling M ultiphase F lows = temp erature of phase = reference temp erature of phase as sp ecified in the Create/Edit M aterials dialo g box The alt ernative treatmen t considers the definition of sensible en thalp y tha t excludes f ormation en thalp y. Sensible en thalp y for each phase is e xpressed as: (26.6) with =298.15 K. Heat F lux R eporting Str ategies When y ou use the alt ernative formula tion, the f ollowing additional v ariable b ecome a vailable f or postpr ocessing under the Phase In teraction... categor y: •Latent Heat In the v ariable selec tion dr op-do wn lists tha t app ear in p ostpr ocessing dialo g boxes, this quan tity will b e app ended with the ID of the c orresponding mass tr ansf er mechanism. Due t o the e xplicit na ture of the alt ernative formula tion, the la tent hea t sour ce app ears as the hea t imbalanc e in hea t flux r eporting . If you w ant to know the hea t imbalanc e due t o the la tent hea t sour ce, you should cr eate a cust om- field func tion f or the mass tr ansf er rate multiplied b y latent hea t, and then r eport it as a v olume in- tegral. ANSY S Fluen t will r eport the f ollowing v alue: (26.7) wher e, = hea t imbalanc e = numb er of mass tr ansf er mechanisms tha t you defined = mass tr ansf er rate of th mechanism = La tent hea t of th mechanism = v olume 26.2.10.2. Mass Transfer Mechanisms When including mass tr ansf er eff ects in a multiphase simula tion, you c an cho ose fr om the f ollowing mechanisms f or each phase pair tha t under goes mass tr ansf er: •constan t-rate •user-defined •popula tion-balanc e •cavita tion •evaporation-c ondensa tion 2113Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Steps f or U sing a M ultiphase M odel•species-mass-tr ansf er •boiling Details f or each mechanism ar e pr ovided in the f ollowing sec tions: 26.2.10.2.1. Constan t-Rate Option 26.2.10.2.2. User-D efined Option 26.2.10.2.3. Popula tion-B alanc e Mechanism 26.2.10.2.4. Cavitation M echanism 26.2.10.2.5. Evaporation-C ondensa tion M echanism 26.2.10.2.6. Species-M ass-T ransf er M echanism 26.2.10.2.7. Boiling M echanism 26.2.10.2.1. Constant-R ate O ption You c an use the constan t-rate option t o sp ecify a c onstan t value f or unidir ectional mass tr ansf er. The constan t-rate must b e en tered in units of 1/time unit. 26.2.10.2.2. User -Defined O ption The user-defined option allo ws you t o implemen t a c orrelation r eflec ting a mo del of y our choic e, through a user-defined func tion. 26.2.10.2.3. Population-B alanc e Mechanism With the popula tion-balanc e mechanism, you c an mo del flo w wher e a numb er densit y func tion is introduced t o acc oun t for the par ticle p opula tion. With the aid of par ticle pr operties (f or e xample , particle siz e, porosity, comp osition, and so on), diff erent par ticles in the p opula tion c an b e distin- guished and their b ehavior c an b e descr ibed. For a c ompr ehensiv e understanding of this option, refer to the P opula tion B alanc e M odule M anual. 26.2.10.2.4. Cavitation Mechanism The cavita tion mechanism allo ws you t o selec t a c avitation mo del. For a c avitating flo w, it is r ecom- mended tha t you selec t liquid as the pr imar y phase and v apor as the sec ondar y phase . The c avitation mo dels ar e available when using mix ture,VOF, and E uler ian multiphase mo dels .You are pr ovided with t wo mo del options: Schner r-Sauer and Zwart-Gerb er-B elamr i.To op en the Cavita tion M odel dialo g box, selec t cavita tion from the Mechanism drop-do wn list. For inf ormation about the c avitation mo dels , refer to Cavitation M odels in the Theor y Guide . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2114Modeling M ultiphase F lowsFigur e 26.9: The C avita tion M odel D ialo g Box •For the Schner r-Sauer mo del, specify the Bubble N umb er D ensit y ( in Equa tion 18.513 in the Fluent Theor y Guide ) under Model C onstan ts.The default v alue of 1e11 is suitable f or most c ases . •For the Zwart-Gerb er-B elamr i mo del, specify the Bubble D iamet er, the Nuclea tion S ite Volume Fraction , the Evaporation C oefficien t, and the Condensa tion C oefficien t under Model C onstan ts. •Under Cavita tion P roperties , specify the Vaporization P ressur e and , if desir ed, a temp erature dep end- ence func tion. In addition t o the metho ds descr ibed in Defining P roperties U sing Temp erature-Dependen t Functions (p.1095 ) (constan t,polynomial ,piec ewise-linear ,piec ewise-p olynomial , or user-defined ), you c an cho ose one of the f ollowing: –taylor-appr oxima tion The taylor-appr oxima tion metho d mo dels the v aporization pr essur e as linear ly varying with temp erature ab out the fr ee-str eam v alue .This appr oach c an impr ove numer ical stabilit y, but is only appr opriate when de viations ab out the fr ee-str eam t emp erature ar e sufficien tly small tha t higher-or der t erms c an b e neglec ted.The e xpression f or the v aporization pr essur e using the taylor-appr oxima tion metho d is: (26.8) wher e is the fr ee-str eam t emp erature, is the la tent hea t, and is a user-mo difiable coefficien t. In the Taylor A ppr oxima tion dialo g box, you will sp ecify Vaporization P ressur e (at the fr ee-str eam t emp erature),Free S tream Temp erature, and Thermal C oefficien t ( ). –tabular-pt-sa t 2115Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Steps f or U sing a M ultiphase M odelThis metho d allo ws you t o sp ecify v aporization pr essur e using a table tha t contains da ta p oints for sa turation t emp erature and sa turation pr essur e. Saturation pr essur e will b e in terpolated based on the sta tic t emp erature from the solution, which is assumed t o be at a sa turated sta te. The table f ormat is descr ibed in Specifying Variables in a Tabular F ormat (p.894). Onc e you selec t tabular-pt-sa t, the Table Input dialo g box op ens wher e you c an selec t the appr opriate table and the names of the c olumns fr om the Saturation Temp erature and Saturation P ressur e selec tion lists . Figur e 26.10: Table Input f or Vaporization P ressur e –tabular-ptl-sa t (available only with Alternative M odeling of Ener gy Sources (p.2111 )) The metho d allo ws you t o specify sa turation pr essur e using a table tha t contains da ta p oints for sa turation t emp erature, saturation pr essur e, and la tent hea t. Saturation pr essur e and la tent hea t will b e in terpolated based on the sta tic t emp erature from the solution, which is assumed t o be at a sa turated sta te. The table f ormat is descr ibed in Specifying Variables in a Tabular F ormat (p.894). Onc e you selec t tabular-ptl-sa t, the Table Input dialo g box op ens wher e you c an selec t the appr opriate table and the names of the c olumns fr om the Saturation Temp erature,Saturation P ressur e and Latent Heat selec tion lists . Note If you ar e using tabular-pt-sa t or tabular-ptl-sa t to sp ecify v aporization pr essur e, you must first r ead an appr opriate table f ollowing the pr ocedur e outlined in Specifying Variables in a Tabular F ormat (p.894). All table da ta must b e in SI units (sa turation temp erature in Kelvin (K), saturation pr essur e in P ascal (P a), and la tent hea t in J oule/Kg). •If you w ant to include the influenc e of turbulenc e on the thr eshold c avitation pr essur e, enable Turbulenc e Factor. If desir ed, you c an adjust the v alue of the Turbulen t Coefficien t. For details ab out the imple- men tation of the Turbulenc e Factor, see Turbulenc e Factor in the Fluent Theor y Guide . By default , the minimum v apor pr essur e limit is set t o 1 P a.The default v alue f or the maximum v apor pressur e limit is set t o fiv e times the lo cal vapor pr essur e with c onsider ation of the turbulen t and ther mal eff ects for each c omputa tional c ell and phase .The default and r ecommended v alue f or the evaporation and c ondensa tion c oefficien ts in the Schner r-Sauer mo del ( and in Equa- Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2116Modeling M ultiphase F lowstion 18.517 in the Fluent Theor y Guide ) are 1 and 0.2, respectively.You c an mo dify these default v alues using the f ollowing e xpert text commands: •solve/set/multiphase-numerics/heat-mass-transfer/cavitation/min-vapor- pressure •solve/set/multiphase-numerics/heat-mass-transfer/cavitation/max-vapor- pressure-ratio •solve/set/multiphase-numerics/heat-mass-transfer/cavitation/schnerr-cond- coeff •solve/set/multiphase-numerics/heat-mass-transfer/cavitation/schnerr-evap- coeff Note •If you use multiple c avitation mass tr ansf er mechanisms in y our simula tion, the v alue y ou specify f or Turbulenc e Factor will aut oma tically apply t o all c avitation mechanisms , ther eby overwriting pr eviously e xisting turbulen t coefficien ts. •If the Mixture multiphase mo del is enabled , then the S inghal et al. cavitation mo del c an b e enabled using the solve/set/expert text command and r esponding yes to use Singhal-et-al cavitation model? .The Singhal-E t-Al Cavita tion M odel option will no w be visible in the Phase In teraction dialo g box, under the Mass tab . Enable this option to include the S inghal et al. cavitation mo del. Refer to Including C avitation E ffects (p.2199 ) for information ab out setting the c avitation par amet ers. Also r efer to Cavitation M odels in the Theor y Guide for inf ormation ab out the S inghal et al. mo del. To disable this mo del, first deselec t the Singhal-E t-Al Cavita tion M odel option in the Phase In teraction dialo g box, then t ype the solve/set/expert text command again and en ter no when ask ed if y ou w ant to use Singhal-et-al cavitation model? For turbulen t flo ws, if one of the phases par ticipa ting in c avitation is pr imar y, then ANSY S Fluen t automa tically enables the gener alized turbulen t diffusion tr eatmen t.The tr eatmen t adds a diffusion sour ce in the v olume fr action equa tion b y assuming the diffusion c oefficien t as a func tion of turbulen t viscosity of the r espective phase .This helps a void instan taneous solution instabilit y due t o cavitation. For mor e inf ormation ab out this tr eatmen t, see Diffusion in VOF M odel in the Fluent Theor y Guide . The gener alized turbulen t diffusion tr eatmen t can b e used f or simula ting flo ws with t wo or mor e phases . By default , for a flo w with mor e than t wo phases , the turbulen t diffusion ac ts b etween primar y and sec ondar y phases only .The turbulen t diffusion b etween sec ondar y phases is not acc oun- ted f or. If you w ant to use the old turbulen t diffusion tr eatmen t supp orted in r eleases pr ior t o Release 19.2, enter the f ollowing t ext commands: solve/set/multiphase-numerics/heat-mass-transfer/cavitation/turbulent- diffusion 2117Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Steps f or U sing a M ultiphase M odeluse generalized treatment of turbulent diffusion [yes] no use old treatment of turbulent diffusion [yes] yes Unlike the gener alized turbulen t diffusion tr eatmen t, the old tr eatmen t is applic able t o only t wo- phase flo ws. If used f or flo ws with mor e than t wo phases , the old tr eatmen t unph ysically acc oun ts for each sec ondar y phase in teracting with the pr imar y phase , despit e the sec ondar y non-v apor phases not par ticipa ting in c avitation. If your w ant to disable the turbulen t diffusion tr eatmen t for c ases wher e the high turbulen t visc osity may be a sour ce of an unstable solution, enter the f ollowing t ext commands: solve/set/multiphase-numerics/heat-mass-transfer/cavitation/turbulent- diffusion use generalized treatment of turbulent diffusion [yes] no use old treatment of turbulent diffusion [yes] no 26.2.10.2.5. Evaporation-C ondensation Mechanism The evaporation-c ondensa tion mass tr ansf er mechanism enables y ou t o apply the e vaporation- condensa tion mo del as the mass tr ansf er mechanism. The VOF and M ixture multiphase mo dels use the L ee mo del (see Lee M odel in the Fluent Theor y Guide ).With the E uler ian multiphase mo del, you can cho ose b etween the L ee mo del and the Thermal P hase C hange mo del (see Thermal P hase Change M odel in the Fluent Theor y Guide ).When y ou selec t evaporation-c ondensa tion under Mechanism in the Phase In teractions dialo g box (Mass tab), you will b e pr ompt ed with the Evaporation-C ondensa tion M odel dialo g box. Note tha t this dialo g box could also b e acc essed b y click ing Edit... next to the evaporation-c ondensa tion mechanism dr op-do wn list. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2118Modeling M ultiphase F lowsFigur e 26.11: The E vaporation-C ondensa tion M odel D ialo g Box (E uler ian M ultiphase M odel) You need t o sp ecify the f ollowing settings: 1.(Euler ian multiphase mo del only) S elec t the e vaporation-c ondensa tion Model.The following mo dels are available: •Lee •Thermal P hase C hange 2.Specify the Saturation Temp erature for y our flo w regime . In addition t o the metho ds descr ibed in Defining P roperties U sing Temp erature-Dependen t Functions (p.1095 ) (constan t,polynomial ,piec ewise- linear ,piec ewise-p olynomial , or user-defined ) you c an cho ose one of the f ollowing: •tabular-pt-sa t The tabular-pt-sa t allo ws you t o sp ecify sa turation t emp erature using a table tha t contains data p oints for sa turation t emp erature and sa turation pr essur e. Saturation t emp erature will be in terpolated based on the absolut e pr essur e from the solution, which is assumed t o be at a sa turated sta te.The table f ormat is descr ibed in Specifying Variables in a Tabular Format (p.894). Onc e you selec t tabular-pt-sa t, the Table Input dialo g box op ens wher e you can selec t the appr opriate table and the names of the c olumns f or y our simula tion fr om the Saturation Temp erature and Saturation P ressur e selec tion lists . •tabular-ptl-sa t (available only with Alternative M odeling of Ener gy Sources (p.2111 )) The metho d allo ws you to sp ecify sa turation t emp erature using a table tha t contains da ta p oints for sa turation t em- perature, saturation pr essur e, and la tent hea t. Saturation t emp erature and la tent hea t will b e 2119Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Steps f or U sing a M ultiphase M odelinterpolated based on absolut e pr essur e from the solution, which is assumed t o be at a sa turated state.The table f ormat is descr ibed in Specifying Variables in a Tabular F ormat (p.894). Onc e you selec t tabular-ptl-sa t, the Table Input dialo g box op ens wher e you c an selec t the appr o- priate table and the names of the c olumns fr om the Saturation Temp erature,Saturation Pressur e and Latent Heat selec tion lists . Note •If you use tabular-pt-sa t or tabular-ptl-sa t to sp ecify sa turation t emp erature, you must first r ead an appr opriate table f ollowing the pr ocedur e outlined in Specifying Variables in a Tabular F ormat (p.894). All table da ta must b e in SI units (sa turation t emp erature in Kelvin (K), saturation pr essur e in P ascal (P a), and la tent hea t in J oule/Kg). •If you use the tabular-pt-sa t,tabular-ptl-sa t,polynomial ,piec ewise-p olynomial , or piec ewise-linear option f or Saturation Temp erature, the pr essur e-dep endenc y must be sp ecified in t erms of absolut e pr essur e. 3.(Lee mo del only) S pecify the Evaporation F requenc y and Condensa tion F requenc y mo del c onstan ts. These v alues c orrespond t o the c oefficien t (Equa tion 18.528 in the Theor y Guide ).The v alues are 0.1 by default. However, not e tha t the bubble diamet er and acc ommo dation c oefficien t are usually not v ery well k nown, so the appr opriate values f or a giv en pr oblem c an b e very diff erent. It is imp ortant to tune the v alues t o ma tch e xperimen tal da ta. 4.(Mixture multiphase mo del only) F or certain mo dels and c onditions , you c an selec t the Semi-M echan- istic boiling mo del t o mo del sub-c ooled nuclea te boiling a t low pr essur e, as descr ibed in Including Semi-M echanistic B oiling (p.2199 ). 5.(Thermal P hase C hange mo del only) S pecify the f ollowing mo del c oefficien ts: •From P hase Sc aling F actor: in Equa tion 18.529 in the Fluent Theor y Guide •To Phase Sc aling F actor: in Equa tion 18.530 in the Fluent Theor y Guide If you ar e using the t wo-resistanc e option f or hea t transf er, these v alues ac t as multipliers f or the phase hea t transf er coefficien ts det ermined f or each phase and the default v alue of 1 is usually appr opriate. If you ar e using one of the other hea t transf er options , then these par amet ers correspond t o the c oefficien t (Equa tion 18.528 in the Theor y Guide ) and should b e tuned based on e xperimen tal da ta. Note For a phase pair , only one e vaporation-c ondensa tion mechanism tha t uses the Thermal Phase C hange mo del c an b e defined , and it c annot b e combined with other mass transf er mechanisms . 26.2.10.2.6. Species-M ass-T ransfer Mechanism The species-mass-tr ansf er mechanism enables y ou t o mo del gener alized in terphase sp ecies mass transf er in either the M ixture mo del or the E uler ian mo del subjec t to the f ollowing c onditions: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2120Modeling M ultiphase F lows•Both phases c onsist of mix tures with a t least t wo sp ecies , and a t least one of sp ecies is pr esen t in b oth phases . •The t wo mix ture phases ar e in c ontact and separ ated b y an in terface. •Species mass tr ansf er can only o ccur b etween the same sp ecies fr om one phase t o the other . For e xample , evaporation/c ondensa tion b etween w ater liquid and w ater vapor. •As in all in terphase mass tr ansf er mo dels in F luen t, if a gas mix ture is in volved in an in terphase sp ecies mass tr ansf er pr ocess, it is alw ays treated as a To Phase and the liquid mix ture as a From P hase . •For the sp ecies in volved in the mass tr ansf er, the mass fr actions in b oth phases must b e det ermined b y solving tr ansp ort equa tions . For e xample , the mass fr actions of w ater liquid and w ater vapor in an evaporation/c ondensa tion c ase must b e solv ed dir ectly fr om the go verning equa tions , rather than algeb- raically or fr om the ph ysical constr aint relations . When y ou selec t species-mass-tr ansf er under Mechanism in the Phase In teractions dialo g box, you will b e pr ompt ed with the Species M ass Transf er M odel dialo g box. Note If multiple phase pairs ha ve the species-mass-tr ansf er mechanism selec ted, the same settings in the Species M ass Transf er M odel dialo g box will b e used f or all phase pairs . 2121Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Steps f or U sing a M ultiphase M odelFigur e 26.12: The S pecies M ass Transf er M odel D ialo g Box The st eps t o configur e the sp ecies mass tr ansf er mo del ar e as f ollows: 1. Under Model Options , cho ose the sub-mo del f or det ermining the d ynamic equilibr ium r elations between the same sp ecies in a pair of phases . Raoult ’s Law Use R aoult ’s La w as descr ibed in Raoult ’s La w in the Fluent Theor y Guide .This mo del is appr opriate for gas-liquid c ases in which the liquid phase c an b e mo deled as an ideal liquid mix ture. If you use Raoult ’s La w, you must sp ecify the sa turation pr essur e as a c onstan t, polynomial, piec ewise-linear , piec e-wise p olynomial, or as a user-defined func tion using the DEFINE_PROPERTY macr o. Henr y’s Law Use H enry’s La w as descr ibed in Henry’s La w in the Fluent Theor y Guide .This mo del is appr opriate for cases in which a gas sp ecies is dissolv ed in to a liquid mix ture phase . If you use H enry’s La w you Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2122Modeling M ultiphase F lowsmust sp ecify the metho d for the Molar F raction or Molar C onc entration .You c an cho ose a c on- stan t,vant-hoff (to use the Van’t Hoff c orrelation), or a user-defined func tion using the DEFINE_MASS_TRANSFER macr o. For the vant-hoff mo del, you will need t o sp ecify Referenc e Henr y Constan t ( in Equa tion 18.569 in the Fluent Theor y Guide ) and Temp erature Dependenc e ( ) in the Vant Hoff’s Correlation dialo g box. Equilibr ium R atio Use the E quilibr ium R atio metho d as descr ibed in Equilibr ium R atio in the Fluent Theor y Guide .This model allo ws you t o sp ecify the equilibr ium r atio as a c onstan t, or as a user-defined func tion. If you use Equilibr ium R atio you must sp ecify a c onstan t or user-defined func tion using the DEFINE_MASS_TRANSFER macr o for Molar F raction ,Molar C onc entration , or Mass F raction . 2. Under Interphase M ass Transf er C oefficien t, cho ose whether y ou w ant to sp ecify the mass tr ansf er coefficien t on a p er-phase basis or on all phases: •If you selec ted Per P hase , you c an cho ose the sub-mo dels f or calcula ting the phase-sp ecific mass transf er coefficien ts and for the sour ce phase and the destina tion phase , respectively using Equa tion 18.558 in the Fluent Theor y Guide .The following mo dels ar e available in ANSY S Fluen t: constan t Specify a c onstan t value f or the mass tr ansf er coefficien t. sher wood-numb er Specify a c onstan t value f or the S herwood Numb er.The mass tr ansf er coefficien t is c alcula ted from Equa tion 18.572 in the Fluent Theor y Guide . ranz-marshall Use the R anz-M arshall mo del as descr ibed in Ranz-M arshall M odel in the Fluent Theor y Guide . The R anz-M arshall mo del is based on b oundar y layer theor y for st eady flo w past a spher ical particle . It is applic able under the f ollowing flo w conditions: hughmar k Use the Hughmar k mo del as descr ibed in Hughmar k Model in the Fluent Theor y Guide .The Hughmar k mo del e xtends the R anz-M arshall mo del f or a wider r ange of r elative Reynolds numb er, . zero-resistanc e Specify z ero-resistanc e mass tr ansf er b etween the bulk phase and in terface. user-defined Use a user-defined func tion f or the mass tr ansf er coefficien t defined with the DEFINE_MASS_TRANSFER macr o. The selec tion of ph ysically c orrect mass tr ansf er correlations is highly pr oblem dep enden t. In the c ase of mass tr ansf er b etween a c ontinuous phase and a disp ersed phase of appr oxim- ately spher ical par ticles , the f ollowing should b e adequa te under most situa tions: –ranz-marshall or hughmar k for the c ontinuous phase 2123Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Steps f or U sing a M ultiphase M odel–zero-resistanc e for the disp ersed phase Using zero-resistanc e for the disp ersed phase implies tha t the mass tr ansf er o ccurs v ery quick ly fr om the in terface to the bulk of the disp ersed phase . Consequen tly, the in terface concentration and bulk c oncentration in the disp ersed phase ar e equal. This is usually v alid for dr oplet e vaporation or gas absor ption/dissolution in bubbles . If ther e exists signific ant resistanc e to the mass tr ansf er on the disp ersed phase side , one of the other c orrelations should b e chosen f or the disp ersed phase . •If you selec t Overall, you c an sp ecify the Overall M ass Transf er C oefficien t in Equa tion 18.558 in the Fluent Theor y Guide either as a constan t or as a user-defined func tion. These options ar e the same as those f or the Per P hase option. The Overall option is r ecommended only if the mass transf er coefficien t in each phase is unk nown. For mor e inf ormation ab out these options , see Mass Transf er C oefficien t Models in the Fluent Theor y Guide . 26.2.10.2.7. Boiling Mechanism The boiling mechanism applies the b oiling mo del as the mass tr ansf er mechanism. This mo del is only a vailable with the E uler ian multiphase mo del (when Boiling is enabled in the Multiphase Model dialo g box). For inf ormation ab out the inputs in Figur e 26.69: The B oiling M odel D ialog Box (p.2246 ), refer to Including the B oiling M odel (p.2241 ). 26.2.11. Defining M ultiphase C ell Z one and B oundar y Conditions The pr ocedur e for setting multiphase c ell and b oundar y conditions is sligh tly diff erent than f or single- phase mo dels .You will need t o set some c onditions separ ately f or individual phases , while other conditions ar e shar ed b y all phases (tha t is, the mix ture), as descr ibed in Boundar y and C ell Z one Conditions f or the M ixture and the Individual P hases (p.2132 ). 26.2.11.1. Steps for S etting B oundar y Conditions Setup → Boundar y Conditions Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2124Modeling M ultiphase F lowsFigur e 26.13: The B oundar y Conditions Task P age The st eps y ou need t o perform for each b oundar y are as f ollows: 1.Selec t the b oundar y in the Zone list in the Boundar y Conditions task page . 2.Set the c onditions f or the mix ture at this b oundar y, if nec essar y. (For inf ormation ab out which c onditions need t o be set f or the mix ture, refer to Boundar y and C ell Z one C onditions f or the M ixture and the Indi- vidual P hases (p.2132 ).) a.In the Phase drop-do wn list , selec t mix ture. b.If the cur rent Type for this z one is c orrect, click Edit... to op en the c orresponding b oundar y condition dialo g box (for e xample , the Pressur e Inlet dialo g box); other wise , cho ose the c orrect zone t ype in the Type drop-do wn list , confir m the change (when pr ompt ed), and the c orresponding dialo g box will op en aut oma tically. c.In the b oundar y condition dialo g box for the selec ted z one t ype (for e xample , the Pressur e Inlet dialo g box for the E uler ian mo del, sho wn in Figur e 26.14: The P ressur e Inlet D ialog Box for a M ix- ture (p.2126 )), specify the mix ture boundar y conditions . 2125Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Steps f or U sing a M ultiphase M odelFigur e 26.14: The P ressur e Inlet D ialo g Box for a M ixture Note tha t only those c onditions tha t apply t o all phases , as descr ibed in Boundar y and C ell Zone C onditions f or the M ixture and the Individual P hases (p.2132 ), will app ear in this dialo g box. For inf ormation ab out inputs r elated t o the r elevant boundar y conditions , refer to the appr o- priate sec tions f or those b oundar y conditions . d.If you ha ve enabled the Wall A dhesion option in the Phase In teraction dialo g box (Surface Tension tab), you need t o sp ecify the c ontact angle a t the w all for each pair of phases as a c onstan t (as sho wn in Figur e 26.15: The Wall D ialog Box for a M ixture in a M ultiphase C alcula tion with Wall A dhe- sion (p.2127 )) or a user-defined func tion (see the Fluen t Customiza tion M anual for mor e inf ormation). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2126Modeling M ultiphase F lowsFigur e 26.15: The Wall D ialo g Box for a M ixture in a M ultiphase C alcula tion with Wall Adhesion The c ontact angle ( in Figur e 26.16: Measur ing the C ontact Angle (p.2128 )) is the angle between the w all and the tangen t to the in terface at the w all, measur ed inside the phase list ed in the lef t column under Wall A dhesion in the Momen tum tab of the Wall dialo g box. For example , if y ou ar e setting the c ontact angle b etween the oil and air phases in the Wall dialo g box sho wn in Figur e 26.15: The Wall D ialog Box for a M ixture in a M ultiphase C alcula tion with Wall A dhesion (p.2127 ), is measur ed inside the oil phase . For mor e inf ormation, refer to Wall Adhesion in the Theor y Guide . 2127Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Steps f or U sing a M ultiphase M odelFigur e 26.16: Measur ing the C ontact Angle The default v alue f or all pairs is 90 degr ees, which is equiv alen t to no w all adhesion eff ects (tha t is, the in terface is nor mal t o the adjac ent wall). A c ontact angle of 45°, for e xample , cor- responds t o water cr eeping up the side of a c ontainer , as is c ommon with w ater in a glass . e.Define additional b oundar y conditions tha t are sp ecific t o the multiphase mo dels . i.(VOF mo del) I f you enabled the Jump A dhesion option in the Phase In teraction dialo g box, specify the c ontact angle a t the p orous jump f or each pair of phases . If you enable the Jump Adhesion option in the Phase In teraction dialo g box, this option b ecomes visible a t each of the porous jump b oundar ies.You c an enable or disable the Jump A dhesion option in the Porous Jump dialo g boxes and pr ovide the inputs f or the c ontact angle a t the desir ed p orous jump boundar y, as sho wn in Figur e 26.17: The P orous J ump D ialog Box Displa ying J ump A dhesion (p.2129 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2128Modeling M ultiphase F lowsFigur e 26.17: The P orous Jump D ialo g Box Displa ying Jump A dhesion The c ontact angle is the angle a t the p orous jump .To constr ain the c ontact angle a t the p orous jump based on p orous or non-p orous fluid z ones , enable the Constr ained Two- Sided A dhesion option. Other wise , if it is disabled , then the f orced t wo-sided adhesion treatmen t is in eff ect. For mor e detail, see Jump A dhesion . f.Click OK onc e you c omplet e the b oundar y condition definition f or the mix ture. 3.Set the c onditions f or each phase a t this b oundar y, if nec essar y. (See Boundar y and C ell Z one C onditions for the M ixture and the Individual P hases (p.2132 ) for inf ormation ab out which c onditions need t o be set for the individual phases .) a.In the Phase drop-do wn list , selec t the phase (f or e xample ,water). Imp ortant Note tha t, when y ou selec t one of the individual phases (r ather than the mix ture), only one t ype of z one app ears in the Type drop-do wn list. It is not p ossible t o assign phase-sp ecific z one t ypes a t a giv en b oundar y; the z one t ype is sp ecified f or the mixture, and it applies t o all of the individual phases . b.Click Edit... to op en the b oundar y condition dialo g box for this phase (f or e xample , the Pressur e Inlet dialo g box, sho wn in Figur e 26.18: The P ressur e Inlet D ialog Box for a P hase (p.2130 )). 2129Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Steps f or U sing a M ultiphase M odelFigur e 26.18: The P ressur e Inlet D ialo g Box for a P hase c.Specify the b oundar y conditions f or the phase . Note tha t only those c onditions tha t apply t o the in- dividual phase , as descr ibed in Boundar y and C ell Z one C onditions f or the M ixture and the Individual Phases (p.2132 ), will app ear in this dialo g box. d.(Secondar y phase only) F or the pr essur e outlet , exhaust fan or outlet v ent boundar y, you c an sp ecify the v olume fr action sp ecific ation metho d as one of the f ollowing options: •Backflo w Volume F raction :You c an define the backflo w volume fr action as a c onstan t, a pr ofile (see Profiles (p.1051 )), or a user-defined func tion (see the Fluen t Customiza tion M anual ). Figur e 26.19: The P ressur e Outlet D ialo g Box for a P hase •From N eighb oring C ell:This option do es not r equir e the sp ecific ation of the backflo w volume fraction, and the v olume fr action v alue is dir ectly tak en fr om the neighb oring c ells. In the c ase of r everse flo w at the pr essur e outlet b oundar y, sometimes it b ecomes tr icky to specify the c orrect values f or the backflo w volume fr action. Incorrect sp ecific ation migh t lead t o instabilit y, convergenc e issues and unph ysical b ehavior.The backflo w volume fr action specific ation fr om the neighb oring in terior c ells c an b e a go od choic e if inf ormation a t the pressur e outlet b oundar y is not k nown. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2130Modeling M ultiphase F lowse.Click OK onc e you c omplet e the b oundar y condition definition f or the phase . 26.2.11.2. Steps for S etting C ell Z one C onditions Setup → Cell Z one C onditions Figur e 26.20: The C ell Z one C onditions Task P age The st eps f or sp ecifying the mix ture and individual phase c ell z one c onditions ar e list ed b elow: 1.Selec t the c ell z one in the Zone list in the Cell Z one C onditions task page . 2.If needed , set the c ell z one c onditions f or the mix ture. (For inf ormation ab out which c onditions need t o be set f or the mix ture, refer to Boundar y and C ell Z one C onditions f or the M ixture and the Individual Phases (p.2132 ).) a.In the Phase drop-do wn list , selec t mix ture. b.Make sur e tha t the selec ted Type is appr opriate for this z one and click Edit.... 2131Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Steps f or U sing a M ultiphase M odelc.In the Fluid dialo g box, set the c ell z one c onditions tha t are applic able t o the mix ture. d.Define additional c ell z one c onditions tha t are sp ecific t o the multiphase mo dels . i.If Zonal D iscr etiza tion is enabled in the Interface M odeling Options dialo g box, you c an sp ecify the Compr essiv e Scheme S lope Limit er in the Multiphase tab of the Fluid dialo g box.The setting of the slop e limit er can b e an y value b etween 0 and 2, inclusiv e.Values of 0, 1, and 2 c or- respond t o first or der up wind , sec ond or der up wind , and c ompr essiv e discr etiza tion, respectively with in termedia te values r esulting in a blended f ormula tion. For mor e details ab out the slop e limit er, refer to The C ompr essiv e Scheme and In terface-M odel-based Variants in the Fluent Theor y Guide . 3.If requir ed, set the c onditions f or each phase . (See Boundar y and C ell Z one C onditions f or the M ixture and the Individual P hases (p.2132 ) for inf ormation ab out which c onditions need t o be set f or the individual phases .) a.In the Phase drop-do wn list , selec t the phase (f or e xample ,water) and click Edit.... b.In the Fluid dialo g box, set the c ell z one c onditions tha t are applic able t o the individual phase . For mor e inf ormation ab out inputs f or c ell z one c onditions , see Fluid C onditions (p.854). 26.2.11.3. Boundar y and C ell Z one C onditions for the M ixture and the Individual Phases The b oundar y conditions y ou need t o sp ecify f or the mix ture and f or the individual phases will dep end on which multiphase mo del y ou ar e using . Details f or each mo del ar e pr ovided in the f ollowing sec tions: 26.2.11.3.1. VOF M odel 26.2.11.3.2. Mixture Model 26.2.11.3.3. Euler ian M odel 26.2.11.3.1. VOF Mo del If you ar e using the VOF mo del, the c onditions y ou need t o sp ecify f or each t ype of b oundar y zone are list ed b elow and summar ized in Table 26.4: Phase-S pecific and M ixture Conditions f or the VOF Model (p.2133 ). •For an inlet v ent, intake fan, pressur e inlet , or v elocity inlet , ther e are no c onditions t o be sp ecified f or the pr imar y phase . For each sec ondar y phase , you will need t o set the v olume fr action as a c onstan t, a profile (see Profiles (p.1051 )), or a user-defined func tion (see the Fluen t Customiza tion M anual ). All other conditions ar e sp ecified f or the mix ture. •For an e xhaust fan, outlet v ent, or pr essur e outlet , ther e are no c onditions t o be sp ecified f or the pr imar y phase . For each sec ondar y phase , you will need t o sp ecify the v olume fr action sp ecific ation metho d as either Backflo w Volume F raction or From N eighb oring C ell (see st ep 3. in Steps f or S etting B oundar y Conditions (p.2124 )). All other c onditions ar e sp ecified f or the mix ture. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2132Modeling M ultiphase F lows•For a mass-flo w inlet , you will need t o set the mass flo w rate, mass flux, or a verage mass flux f or each individual phase . All other c onditions ar e sp ecified f or the mix ture. Imp ortant Note tha t if y ou r ead a VOF c ase tha t was set up in a v ersion of ANSY S Fluen t prior t o 6.1, you will need t o redefine the c onditions a t the mass-flo w inlets . •For an axis , fan, outflo w, periodic, porous jump , radia tor, solid , symmetr y, or w all z one , all c onditions ar e specified f or the mix ture.There are no c onditions t o be set f or the individual phases . •For a w all z one , you c an sp ecify the c ontact angle f or the mix ture if the w all adhesion option is enabled . •For a fluid z one , mass sour ces ar e sp ecified f or the individual phases , and all other sour ces ar e sp ecified for the mix ture. –If the fluid z one is not p orous, all other c onditions ar e sp ecified f or the mix ture. –If the fluid z one is p orous, you will enable the Porous Z one option in the Fluid dialo g box for the mixture.The p orosity inputs (if r elevant) ar e also sp ecified f or the mix ture.The r esistanc e coefficien ts and dir ection v ectors, however, are sp ecified separ ately f or each phase . See User Inputs f or P orous Media (p.872) for the mix ture. –If Open C hannel F low and/or Open C hannel Wave BC is/ar e enabled in the Multiphase M odel dialo g box, then the Numer ical B each option b ecomes a vailable under the Multiphase tab of the Fluid dialo g box.To lear n ho w to include numer ical beach in y our simula tion, refer to Numer ical Beach Treatmen t for Op en C hannels (p.2167 ). See Cell Z one and B oundar y Conditions (p.835) for details ab out the r elevant conditions f or each type of b oundar y. Note tha t the pr essur e far-field b oundar y is not a vailable with the VOF mo del. Table 26.4: Phase-S pecific and M ixture Conditions f or the VOF M odel Mixture Secondar y Phase Primar y Phase Type all others volume fr action nothing inlet v ent, intake fan, pressur e inlet , velocity inlet all others volume fr action specific ation metho dnothing exhaust fan, outlet v ent, pressur e outlet all others mass flo w/flux mass flo w/flux mass-flo w inlet all others nothing nothing axis; fan; outflo w; periodic; porous jump; radia tor; solid; symmetr y; wall not a vailable not a vailable not a vailable pressur e far-field porous z one; porosity; all othersmass sour ce; other porous inputsmass sour ce; other porous inputsfluid 26.2.11.3.2. Mixture Mo del If you ar e using the mix ture mo del, the c onditions y ou need t o sp ecify f or each t ype of b oundar y zone ar e list ed b elow and summar ized in Table 26.5: Phase-S pecific and M ixture Conditions f or the Mixture M odel (p.2134 ). 2133Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Steps f or U sing a M ultiphase M odel•For an e xhaust fan, outlet v ent, or pr essur e outlet , ther e are no c onditions t o be sp ecified f or the pr imar y phase . For each sec ondar y phase , you will need t o sp ecify the v olume fr action sp ecific ation metho d as either Backflo w Volume F raction or From N eighb oring C ell (step 3 in Steps f or S etting B oundar y Conditions (p.2124 ). All other c onditions ar e sp ecified f or the mix ture. •For an inlet v ent, intake fan, or pr essur e inlet , you will sp ecify f or the mix ture which dir ection sp ecific ation metho d will b e used a t this b oundar y (Normal t o Boundar y or Direction Vector). If you selec t the Dir- ection Vector specific ation metho d, you will sp ecify the c oordina te sy stem (3D only) and flo w-dir ection comp onen ts for the individual phases . For each sec ondar y phase , you will need t o set the v olume fr action (as descr ibed ab ove). All other c onditions ar e sp ecified f or the mix ture. •For a mass-flo w inlet , you will need t o set the mass flo w rate, mass flux, or a verage mass flux f or each individual phase . All other c onditions ar e sp ecified f or the mix ture. Imp ortant Note tha t if y ou r ead a mix ture multiphase c ase tha t was set up in a v ersion of ANSY S Fluen t previous t o 6.1, you will need t o redefine the c onditions a t the mass-flo w inlets . •For a v elocity inlet , you will sp ecify the v elocity for the individual phases . For each sec ondar y phase , you will need t o set the v olume fr action (as descr ibed ab ove). All other c onditions ar e sp ecified f or the mix ture. •For an axis , fan, outflo w, periodic, porous jump , radia tor, solid , symmetr y, or w all z one , all c onditions ar e specified f or the mix ture.There are no c onditions t o be set f or the individual phases . Outflo w boundar y conditions ar e not a vailable f or the c avitation mo del. •For a fluid z one , mass sour ces ar e sp ecified f or the individual phases , and all other sour ces ar e sp ecified for the mix ture. If the fluid z one is not p orous, all other c onditions ar e sp ecified f or the mix ture. If the fluid z one is p orous, you will enable the Porous Z one option in the Fluid dialo g box for the mix ture.The p orosity inputs (if r elevant) ar e also sp ecified f or the mix ture.The r esistanc e coefficien ts and dir ection v ectors, however, are sp ecified separ ately f or each phase . See User Inputs for P orous M edia (p.872) for details ab out these inputs . All other c onditions ar e sp ecified f or the mixture. See Cell Z one and B oundar y Conditions (p.835) for details ab out the r elevant conditions f or each type of b oundar y. Note tha t the pr essur e far-field b oundar y is not a vailable with the mix ture mo del. Table 26.5: Phase-S pecific and M ixture Conditions f or the M ixture M odel Mixture Secondar y Phase Primar y Phase Type all others volume fr action specific ation metho dnothing exhaust fan; outlet v ent; pressur e outlet dir. spec. metho d; all otherscoord. system; flow direction; volume fr actioncoord. system; flow directioninlet v ent; intake fan; pressur e inlet all others mass flo w/flux mass flo w/flux mass-flo w inlet all others velocity; volume fr action velocity velocity inlet all others nothing nothing axis; fan; outflo w (n/a f or cavitation mo del); periodic; Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2134Modeling M ultiphase F lowsMixture Secondar y Phase Primar y Phase Type porous jump; radia tor; solid; symmetr y; wall not a vailable not a vailable not a vailable pressur e far-field porous z one; porosity; all othersmass sour ce; other p orous inputsmass sour ce; other porous inputsfluid 26.2.11.3.3. Eulerian Mo del If you ar e using the E uler ian mo del, the c onditions y ou need t o sp ecify f or each t ype of b oundar y zone ar e list ed b elow and summar ized in •Table 26.6: Phase-S pecific and M ixture Conditions f or the E uler ian M odel (f or Laminar F low) (p.2138 ) •Table 26.7: Phase-S pecific and M ixture Conditions f or the E uler ian M odel (with the M ixture Turbulenc e Model) (p.2138 ) •Table 26.8: Phase-S pecific and M ixture Conditions f or the E uler ian M odel (with the D ispersed Turbu- lenc e Model) (p.2139 ) •Table 26.9: Phase-S pecific and M ixture Conditions f or the E uler ian M odel (with the P er-P hase Turbu- lenc e Model) (p.2139 ) Note tha t the sp ecific ation of turbulenc e par amet ers will dep end on which of the thr ee multiphase turbulenc e mo dels y ou ar e using , as indic ated in •Table 26.7: Phase-S pecific and M ixture Conditions f or the E uler ian M odel (with the M ixture Turbulenc e Model) (p.2138 ) •Table 26.8: Phase-S pecific and M ixture Conditions f or the E uler ian M odel (with the D ispersed Turbulenc e Model) (p.2139 ) •Table 26.9: Phase-S pecific and M ixture Conditions f or the E uler ian M odel (with the P er-P hase Turbulenc e Model) (p.2139 ) See Turbulenc e M odels in the Theor y Guide and Modeling Turbulenc e (p.2229 ) for mor e inf ormation about multiphase turbulenc e mo dels . •For an e xhaust fan, outlet v ent, or pr essur e outlet , ther e are no c onditions t o be sp ecified f or the pr imar y phase if y ou ar e mo deling laminar flo w or using the mix ture turbulenc e mo del (the default multiphase turbulenc e mo del), except f or backflo w total t emp erature if hea t transf er is on. For each sec ondar y phase , you will need t o sp ecify the v olume fr action sp ecific ation metho d as either Backflo w Volume F raction or From N eighb oring C ell (step 3 in Steps f or S etting B oundar y Conditions (p.2124 ). If the phase is gr anular , you will also need t o set its backflo w gr anular t emp er- ature. If hea t transf er is on, you will also need t o set the backflo w total t emp erature. If you ar e using the mix ture turbulenc e mo del, you will need t o sp ecify the turbulenc e boundar y conditions f or the mix ture. If you ar e using the disp ersed turbulenc e mo del, you will need t o specify them f or the pr imar y phase . If you ar e using the p er-phase turbulenc e mo del, you will need t o sp ecify them f or the pr imar y phase and f or each sec ondar y phase . All other c onditions ar e sp ecified f or the mix ture. 2135Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Steps f or U sing a M ultiphase M odel•For an inlet v ent, intake fan, or pr essur e inlet , you will sp ecify f or the mix ture which dir ection sp ecific ation metho d will b e used a t this b oundar y (Normal t o Boundar y or Direction Vector). If you selec t the Dir- ection Vector specific ation metho d, you will sp ecify the c oordina te sy stem (3D only) and flo w-dir ection comp onen ts for the individual phases . If hea t transf er is on, you will also need t o set the t otal t emp erature for the individual phases . For each sec ondar y phase , you will need t o set the v olume fr action (as descr ibed ab ove). If the phase is gr anular , you will also need t o set its gr anular t emp erature. If you ar e using the mix ture turbulenc e mo del, you will need t o sp ecify the turbulenc e boundar y conditions f or the mix ture. If you ar e using the disp ersed turbulenc e mo del, you will need t o specify them f or the pr imar y phase . If you ar e using the p er-phase turbulenc e mo del, you will need t o sp ecify them f or the pr imar y phase and f or each sec ondar y phase . All other c onditions ar e sp ecified f or the mix ture. •For a mass-flo w inlet , you will need t o set the mass flo w rate, mass flux, or a verage mass flux f or each individual phase .You will also need t o sp ecify the t emp erature of each phase , sinc e the ener gy equa tions are solv ed f or each phase . For mass-flo w inlet b oundar y conditions , you c an sp ecify the slip v elocity between phases .When you selec t a mass-flo w inlet b oundar y for the sec ondar y phase , two options will b e available f or the Slip Velocity Specific ation M etho d, as sho wn in Figur e 26.21: Mass-F low Inlet B oundar y Condition D ialog Box (p.2137 ) : –Velocity Ratio The v alue f or the Velocity Ratio is the sec ondar y phase t o pr imar y phase v elocity ratio. By de- fault , it is 1.0, which means v elocities ar e the same (no slip). By en tering a r atio tha t is gr eater than 1.0, you ar e indic ating a lar ger sec ondar y phase v elocity. Other wise , you c an en ter a r atio that is less than 1.0 t o indic ate a smaller sec ondar y phase v elocity. –Volume F raction If you sp ecify the v olume fr action a t an inlet , ANSY S Fluen t will c alcula te the phase v elocities . Imp ortant –If a sec ondar y phase has z ero mass flux (tha t is, the E uler ian mo del is used t o run a single phase c ase), neither Velocity Ratio nor Volume F raction will aff ect the solution. –The Velocity Ratio and Volume F raction slip v elocity metho ds c annot b e mix ed f or diff erent secondar y phases .That is, you should sp ecify one or the other c ondition f or all phases . The v olume fr action is basic ally the fr action of ar ea c overed b y tha t phase . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2136Modeling M ultiphase F lowsFigur e 26.21: Mass-F low Inlet B oundar y Condition D ialo g Box •For a v elocity inlet , you will sp ecify the v elocity for the individual phases . If hea t transf er is on, you will also need t o set the sta tic t emp erature for the individual phases . For each sec ondar y phase , you will need t o set the v olume fr action (as descr ibed ab ove). If the phase is gr anular , you will also need t o set its gr anular t emp erature. If you ar e using the mix ture turbulenc e mo del, you will need t o sp ecify the turbulenc e boundar y conditions f or the mix ture. If you ar e using the disp ersed turbulenc e mo del, you will need t o specify them f or the pr imar y phase . If you ar e using the p er-phase turbulenc e mo del, you will need t o sp ecify them f or the pr imar y phase and f or each sec ondar y phase . All other c onditions ar e sp ecified f or the mix ture. •For an axis , outflo w, degassing , periodic, solid , or symmetr y zone , all c onditions ar e sp ecified f or the mixture.There are no c onditions t o be set f or the individual phases . •For a w all z one , shear c onditions ar e sp ecified f or the individual phases . All other c onditions ar e sp ecified for the mix ture, including ther mal b oundar y conditions , if hea t transf er is on. •For a fluid z one , all sour ce terms and fix ed v alues ar e sp ecified f or the individual phases , unless y ou ar e using the mix ture turbulenc e mo del or the disp ersed turbulenc e mo del. If you ar e using the mix ture turbulenc e mo del, sour ce terms and fix ed v alues f or turbulenc e are sp ecified inst ead f or the mix ture. If you ar e using the disp ersed turbulenc e mo del, the y are sp ecified only f or the pr imar y phase . –If the fluid z one is not p orous, all other c onditions ar e sp ecified f or the mix ture. –If the fluid z one is p orous, you will enable the Porous Z one option in the Fluid dialo g box for the mixture.The p orosity inputs (if r elevant) ar e also sp ecified f or the mix ture.The r esistanc e coefficien ts and dir ection v ectors, however, are sp ecified separ ately f or each phase . See User Inputs f or P orous Media (p.872) for details ab out these inputs . All other c onditions ar e sp ecified f or the mix ture. 2137Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Steps f or U sing a M ultiphase M odelSee Cell Z one and B oundar y Conditions (p.835) for details ab out the r elevant conditions f or each type of b oundar y. Note tha t the pr essur e far-field , fan, porous jump , radia tor, and mass-flo w inlet boundar ies ar e not a vailable with the E uler ian mo del. Table 26.6: Phase-S pecific and M ixture Conditions f or the E uler ian M odel (f or L aminar F low) Mixture Secondar y Phase Primar y Phase Type all others volume fr action sp ecific ation metho d; gran. temp erature (tot. temp erature)(tot. temp erature) exhaust fan; outlet vent; pressur e outlet dir. spec. metho d; all otherscoord. system; flow dir ection; volume fr action; gran. temp erature (tot. temp erature)coord. system; flow direction (t ot. temp erature)inlet v ent; intake fan; pressur e inlet all others velocity; volume fr action; gran. temp erature (tot. temp erature)velocity (tot. temp erature)velocity inlet all others mass flo w rate/flux; velocity ratio/v olume fr action; gran. temp erature (temp erature)mass flo w rate/flux (temp erature)mass-flo w inlet all others nothing nothing axis; outflo w; degassing; periodic; solid; symmetr y all others shear c ondition shear c ondition wall not a vailable not a vailable not a vailable pressur e far-field; fan; porous jump; radia tor porous z one; porosity; allall sour ce terms; all fix ed v alues; other p orous inputsall sour ce terms; all fixed v alues; other porous inputsfluid Table 26.7: Phase-S pecific and M ixture Conditions f or the E uler ian M odel (with the M ixture Turbulenc e M odel) Mixture Secondar y Phase Primar y Phase Type all others volume fr action sp ecific ation metho d; gran. temp erature (tot. temp erature)(tot. temp erature) exhaust fan; outlet vent; pressur e outlet dir. spec. metho d; all otherscoord. system; flow dir ection; volume fr action; gran. temp erature (tot. temp erature)coord. system; flow direction (t ot. temp erature)inlet v ent; intake fan; pressur e inlet all others velocity; volume fr action; gran. temp erature (tot. temp erature)velocity (tot. temp erature)velocity inlet all others mass flo w rate/flux; velocity ratio/v olume fr action; gran. temp erature (temp erature)mass flo w rate/flux (temp erature)mass-flo w inlet all others nothing nothing axis; outflo w; degassing; periodic; solid; symmetr y all others shear c ondition shear c ondition wall Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2138Modeling M ultiphase F lowsMixture Secondar y Phase Primar y Phase Type not a vailable not a vailable not a vailable pressur e far-field; fan; porous jump; radia tor sour ce terms f or turbulenc e; fixedother sour ce terms; other fix ed values; other p orous inputsother sour ce terms; other fix ed v alues; other p orous inputsfluid values f or turbulenc e; porous zone; porosity; all Table 26.8: Phase-S pecific and M ixture Conditions f or the E uler ian M odel (with the D ispersed Turbulenc e M odel) Mixture Secondar y Phase Primar y Phase Type all others volume fr action sp ecific ation metho d; gran. temp erature (tot. temp erature)turb . par amet ers (t ot. temp erature)exhaust fan; outlet vent; pressur e outlet dir. spec. metho d; all otherscoord. system; flow dir ection; volume fr action; gran. temp erature (tot. temp erature)coord. system; flow direction; turb . par amet ers; (tot. temp erature)inlet v ent; intake fan; pressur e inlet all others velocity; volume fr action; gran. temp erature (tot. temp erature)velocity; turb . par amet ers (tot. temp erature)velocity inlet all others mass flo w rate/flux; velocity ratio/v olume fr action; gran. temp erature (temp erature)mass flo w rate/flux; turb . paramet ers (t emp erature)mass-flo w inlet all others nothing nothing axis; outflo w; degassing; periodic; solid; symmetr y all others shear c ondition shear c ondition wall not a vailable not a vailable not a vailable pressur e far-field; fan; porous jump; radia tor porous z one; porosity; allmomen tum and mass sour ces; momen tum and mass fix ed values; other p orous inputsmomen tum, mass , turb . sour ces; momen tum, mass , turb . fixed v alues; other porous inputsfluid Table 26.9: Phase-S pecific and M ixture Conditions f or the E uler ian M odel (with the P er-P hase Turbulenc e M odel) Mixture Secondar y Phase Primar y Phase Type all others volume fr action sp ecific ation metho d; turb . par amet ers; gran. temp erature (tot. temp erature)turb . par amet ers (t ot. temp erature)exhaust fan; outlet vent; pressur e outlet dir. spec. metho d; all otherscoord. system; flow dir ection; volume fr action; turb . paramet ers; gran. temp erature (tot. temp erature)coord. system; flow direction; turb . par amet ers (tot. temp erature)inlet v ent; intake fan; pressur e inlet 2139Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Steps f or U sing a M ultiphase M odelMixture Secondar y Phase Primar y Phase Type all others velocity; volume fr action; turb . paramet ers; gran. temp erature (tot. temp erature)velocity; turb . par amet ers (tot. temp erature)velocity inlet all others mass flo w rate/flux; velocity ratio/v olume fr action; gran. temp erature (temp erature)mass flo w rate/flux; tub . paramet ers (t emp erature)mass-flo w inlet all others nothing nothing axis; outflo w; degassing; periodic; solid; symmetr y all others shear c ondition shear c ondition wall not a vailable not a vailable not a vailable pressur e far-field; fan; porous jump; radia tor porous z one; porosity; all othersmomen tum, mass , turb . sour ces; momen tum, mass , turb . fixed values; other p orous inputsmomen tum, mass , turb . sour ces; momen tum, mass , turb . fixed v alues; other p orous inputsfluid 26.2.11.4. Steps for C opying C ell Z one and B oundar y Conditions The st eps f or c opying c ell z one and b oundar y conditions f or a multiphase flo w ar e sligh tly diff erent from those descr ibed in Copying C ell Z one and B oundar y Conditions (p.840) for a single-phase flo w. The mo dified st eps ar e list ed b elow: 1.In the Cell Z one C onditions or Boundar y Conditions task page , click the Copy... butt on.This will op en the Copy Conditions dialo g box. 2.In the From C ell Z one or From B oundar y Zone list, selec t the z one tha t has the c onditions y ou w ant to copy. 3.In the To Cell Z ones or To Boundar y Zones list, selec t the z one or z ones t o which y ou w ant to copy the conditions . 4.In the Phase drop-do wn list , selec t the phase f or which y ou w ant to copy the c onditions (either mix ture or one of the individual phases). Imp ortant Note tha t copying the b oundar y conditions f or one phase do es not aut oma tically r esult in the b oundar y conditions f or the other phases and the mix ture being c opied as w ell. You need t o copy the c onditions f or each phase on each b oundar y of in terest. 5.Click Copy. ANSY S Fluen t will set all of the selec ted phase ’s (or mix ture’s) boundar y conditions on the zones selec ted in the To Cell Z ones or To Boundar y Zones list t o be the same as tha t phase ’s conditions on the z one selec ted in the From C ell Z one or From B oundar y Zone list. (You c annot c opy a subset of the c onditions , such as only the ther mal c onditions .) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2140Modeling M ultiphase F lowsSee Copying C ell Z one and B oundar y Conditions (p.840) for additional inf ormation ab out c opying boundar y conditions , including limita tions . 26.2.12. Setting Initial Volume F ractions Onc e you ha ve initializ ed the flo w (as descr ibed in Initializing the S olution (p.2604 )), you c an define the initial distr ibution of the phases . For a tr ansien t simula tion, this distr ibution will ser ve as the initial condition a t ; for a st eady-sta te simula tion, setting an initial distr ibution c an pr ovide added stabilit y in the ear ly stages of the c alcula tion. You c an pa tch an initial v olume fr action f or each sec ondar y phase using the Patch D ialog Box (p.3622 ). Solution → Initializa tion Patch... If the r egion in which y ou w ant to pa tch the v olume fr action is defined as a separ ate cell z one , you can simply pa tch the v alue ther e. Other wise , you c an cr eate a c ell “regist er” tha t contains the appr o- priate cells and pa tch the v alue in the r egist er. See Patching Values in S elec ted C ells (p.2607 ) for details . 26.2.12.1. Options for P atching Volume F raction You ha ve additional options f or ho w the v olume fr action is pa tched in a user-defined r egist er. By default the pa tching pr ocedur e will initializ e all of the c ells in the r egist er with the sp ecified v olume fraction, without an y sp ecial tr eatmen t for c ells tha t are in tersec ted b y the fluid-fluid in terface. Patch Rec onstr ucted In terface This option uses piec ewise-linear in terface reconstr uction t o iden tify the fluid-fluid in terface and patches the ac tual v olume fr action field in the c ells tha t intersec t the in terface. 2141Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Steps f or U sing a M ultiphase M odelImp ortant The Patch Rec onstr ucted In terface algor ithm r equir es tha t the r egist er coordina tes in the Region A daption dialo g box be well-or dered.That is: X M in < X M ax;Y Min < Y M ax;Z M in < Z M ax. In par ticular , if y ou use the Selec t Points with Mouse feature to sp ecify the c oordina tes, be sur e tha t this c ondition is met. The Patch Rec onstr ucted In terface will b e applied only on the last r egist er tha t was defined , even if multiple r egist ers ar e selec ted in the Patch dialo g box. Therefore, it is r ecommended tha t you cr eate and pa tch r egist ers one a t a time . Volumetr ic Smoothing This option smo oths the v olume fr action field on-demand b y tak ing the v olumetr ic average o ver the c ell neighb ors.This c an help pr ovide b etter solution stabilit y at star tup. After enabling Volumetr ic Smoothing , you c an click Smooth to apply the smo othing . Note tha t the smo othing is applied t o the v olume fr action field f or all phases in the full domain. The Smoothing Relaxa tion F actor controls the degr ee of smo othing applied .You c an sp ecify a v alue b etween 0 (no smo othing) and 1 (max- imum smo othing). For most c ases , the default v alue is r ecommended . For fine meshes y ou ma y choose t o try a lar ger v alue t o aid solution star tup. However, excessiv ely lar ge v alues c an ha ve an undesir able eff ect dur ing the solution as in terface shar pening discr etiza tion schemes ma y det eriorate the initial field . The Smooth command c an b e used a t an y time af ter the solution has b een initializ ed. It can ther efore also b e used af ter reading a da ta file f or p ostpr ocessing . However, not e tha t the smo othed field will o verwrite the or iginal v olume fr action field in this c ase. Also not e tha t you must selec t a sec ondar y phase v ariable fr om the dr op-do wn list in the P atch dialo g box to expose the Volumetr ic S moothing option. 26.3. Setting U p the VOF M odel For back ground inf ormation ab out the VOF mo del and the limita tions tha t apply , refer to Overview of the VOF M odel in the Theor y Guide . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2142Modeling M ultiphase F lowsThis sec tion is or ganiz ed as f ollows: 26.3.1. Solving S teady-State VOF P roblems 26.3.2. Guidelines f or U sing the M ultiphase P seudo Transien t Solver 26.3.3. Including C oupled L evel Set with the VOF M odel 26.3.4. Modeling Op en C hannel F lows 26.3.5. Modeling Op en C hannel Wave Boundar y Conditions 26.3.6. Recommenda tions f or Op en C hannel Initializa tion 26.3.7. Numer ical Beach Treatmen t for Op en C hannels 26.3.8. Defining the P hases f or the VOF M odel 26.3.9. Setting Time-D ependen t Paramet ers f or the Explicit Volume F raction F ormula tion 26.3.10. Modeling S olidific ation/M elting 26.3.11. Using the VOF-t o-DPM M odel Transition f or D ispersion of Liquid in G as 26.3.1. Solving S tead y-State VOF P roblems For st eady-sta te VOF pr oblems , ANSY S Fluen t aut oma tically enables the Pseudo Transien t solution metho d along with the Coupled pressur e-velocity coupling scheme f or b etter stabilit y and fast er convergenc e. For mor e inf ormation ab out pseudo tr ansien t solutions , see Performing P seudo Transien t Calcula tions (p.2617 ). 26.3.2. Guidelines f or U sing the M ultiphase P seudo Transien t Solver When using the Pseudo Transien t solution metho d in multiphase applic ations , follow the guidelines provided b elow: •For the fix ed ( User-S pecified ) time st ep metho d, you must pr ovide a suitable pseudo time st ep siz e to the solv er.You c an use the Automa tic time st ep metho d to estima te the pseudo time st ep siz e for the simula tion. This c an b e done b y setting the Verb osit y to 1 and simula ting y our c ase f or a f ew it erations .The pseudo- time st ep siz e will b e pr inted in the F luen t console . •For the Automa tic time st ep metho d, decr easing the Time Sc ale F actor to a lo wer value (ab out 0.3) will provide b etter solution stabilit y. •Sometimes , for stiff flo w pr oblems , convergenc e ma y not b e achie ved when using the Automa tic time step metho d. In such c ases , consider swit ching t o the fix ed ( User-S pecified ) time st ep metho d inst ead. •For st eady sta te pr oblems , you should ne ver evalua te convergenc e based on r esiduals alone .To better judge c onvergenc e, you should also monit or appr opriate field v ariables a t a par ticular lo cation un til the value st ops changing . •The Coupled with Volume F ractions option is r ecommended f or op en channel flo w applic ations . 26.3.3. Including C oupled L evel S et with the VOF M odel When using the VOF f ormula tion, you c an c ouple the le vel set metho d with it t o help o vercome some limita tions tha t exist in the in terface tracking metho d of the VOF mo del and the le vel set metho d.To use the c oupled le vel set metho d with VOF, perform the f ollowing: 1.Open the Multiphase M odel dialo g box. Setup → Models → Multiphase → Edit... 2143Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the VOF M odel2.Under Model, enable Volume of F luid . 3.Under Coupled L evel S et + VOF, enable Level S et (see Figur e 26.1: Multiphase M odel D ialog Box for the VOF M odel (p.2094 )). 4.(optional) In some c ases , spur ious cur rents can ar ise fr om the applic ation of the sur face tension force in the momen tum equa tion. In these c ases y ou c an use the /define/models/mul- tiphase/coupled-level-set text command t o use a r evised f ormula tion of the sur face tension f orce tha t weigh ts the f orce towards the hea vier phase in the in terface cells.You c an cho ose from none (the default), density-correction , and heaviside-correction . After the Level S et option is enabled , proceed as y ou nor mally w ould when setting up the VOF model (descr ibed in Setting U p the VOF M odel (p.2142 )). For theor etical inf ormation, refer to Coupled Level-Set and VOF M odel. Note When using the Level S et option, the r ecommended scheme is the geo-r econstr uct scheme (see The G eometr ic Reconstr uction Scheme ). Imp ortant •The le vel set metho d is only suitable f or two-phase flo w regime , wher e two fluids ar e not interpenetr ating . •The le vel set mo del c an only b e used when the VOF mo del is tur ned on. No mass tr ansf er is allo wed. •The le vel set metho d is not c ompa tible with the d ynamic mesh mo del. Normally , zero flux of the le vel set func tion is set as the default f or the b oundar y conditions . Due t o the geometr ical re-initializa tion pr ocedur e at each time st ep, the b oundar y conditions shall not ha ve any signific ant eff ect on the r esults . For mor e inf ormation, see Re-initializa tion of the L evel-set F unction via the G eometr ical M etho d. 26.3.4. Modeling Op en C hannel F lows Using the VOF f ormula tion, open channel flo ws can b e mo deled in ANSY S Fluen t.To star t using the open channel flo w b oundar y condition, perform the f ollowing: 1.Enable Gravity and set the gr avitational acc eleration fields . Setup → Gener al Gravity → On 2.Enable the v olume of fluid mo del. a.Open the Multiphase M odel dialo g box. Setup → Models → Multiphase → Edit... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2144Modeling M ultiphase F lowsb.Under Model, enable Volume of F luid . c.Under Formula tion , selec t either Implicit or Explicit . 3.Under VOF S ub-M odels , selec t Open C hannel F low. Note The default VOF f ormula tion is set t o Implicit after enabling the Open C hannel F low option. This is done t o allo w the use of lar ger time st ep siz es for such applic ations . In or der t o set sp ecific par amet ers f or a par ticular b oundar y for op en channel flo ws, enable the Open Channel option in the Multiphase tab of the c orresponding b oundar y condition dialo g box. Table 26.10: Open C hannel B oundar y Paramet ers f or the VOF M odel (p.2145 ) summar izes the t ypes of boundar ies a vailable t o the op en channel flo w b oundar y condition, and the additional par amet ers needed t o mo del op en channel flo w. For mor e inf ormation on setting b oundar y condition par amet ers, see Cell Z one and B oundar y Conditions (p.835). Table 26.10: Op en C hannel B oundar y Paramet ers f or the VOF M odel Paramet er Boundar y Type Inlet G roup ID; Secondar y Phase f or Inlet; Flow Specific ation M etho d; Free Sur face Level, Bottom L evel;Velocity Magnitudepressur e inlet Outlet G roup ID; Pressur e Specific ation M etho d; Free Sur face Level; Bottom L evel pressur e outlet Inlet G roup ID; Secondar y Phase f or Inlet; Free Sur face Level; Bottom L evel; Mass Flow R ates for the P hasesmass-flo w inlet Secondar y Phase f or Inlet; Free Sur face Level, Averaged Velocity Inputs/S egregated Velocity Inputs (A vailable with Op en C hannel Wave Boundar y Condition)velocity inlet Flow R ate Weigh ting outflo w Further details ar e pr ovided in the f ollowing sec tions: 26.3.4.1. Defining Inlet G roups 26.3.4.2. Defining Outlet G roups 26.3.4.3. Setting the Inlet G roup 26.3.4.4. Setting the Outlet G roup 26.3.4.5. Determining the F ree Sur face Level 26.3.4.6. Determining the B ottom L evel 26.3.4.7. Specifying the Total H eigh t 26.3.4.8. Determining the Velocity Magnitude 26.3.4.9. Determining the S econdar y Phase f or the Inlet 26.3.4.10. Determining the S econdar y Phase f or the Outlet 26.3.4.11. Choosing the P ressur e Specific ation M etho d 26.3.4.12. Choosing the D ensit y Interpolation M etho d 26.3.4.13. Open C hannel F low Compa tibilit y with Velocity Inlet 26.3.4.14. Limita tions 26.3.4.15. Recommenda tions f or Setting U p an Op en C hannel F low Problem 2145Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the VOF M odel26.3.4.1. Defining Inlet Gr oups Open channel sy stems in volve the flo wing fluid (the sec ondar y phase) and the fluid ab ove it (the primar y phase). If both phases en ter thr ough the separ ate inlets (f or e xample ,inlet-phase2 and inlet-phase1 ), these t wo inlets f orm an inlet gr oup .This inlet gr oup is r ecogniz ed b y the par amet er Inlet G roup ID , which will b e same f or b oth the inlets tha t mak e up the inlet gr oup . On the other hand , if b oth the phases en ter thr ough the same inlet (f or e xample ,inlet-combined ), then the inlet itself r epresen ts the inlet gr oup . Imp ortant In thr ee-phase flo ws, only one sec ondar y phase is allo wed t o pass thr ough one inlet gr oup . 26.3.4.2. Defining O utlet Gr oups Outlet-gr oups c an b e defined in the same manner as the inlet gr oups . Imp ortant In thr ee-phase flo ws, the outlet should r epresen t the outlet gr oup , tha t is, separ ate outlets for each phase ar e not r ecommended in thr ee-phase flo ws. 26.3.4.3. Setting the Inlet Gr oup For pr essur e inlets and mass-flo w inlets , the Inlet G roup ID is used t o iden tify the diff erent inlets that are par t of the same inlet gr oup . For instanc e, when b oth phases en ter thr ough the same inlet (single fac e zone), then those phases ar e par t of one inlet gr oup and y ou w ould set the Inlet G roup ID to 1 f or tha t inlet (or inlet gr oup). In the c ase wher e the same inlet gr oup has separ ate inlets (diff erent fac e zones) f or each phase , then the Inlet G roup ID will b e the same f or each inlet of tha t group . When sp ecifying the inlet gr oup , use the f ollowing guidelines: •Since the Inlet G roup ID is used t o iden tify the inlets of the same inlet gr oup , gener al inf ormation such as Free S urface Level,Bottom L evel, or the mass flo w rate for each phase should b e the same f or each inlet of the same inlet gr oup . •You should sp ecify a diff erent Inlet G roup ID for each distinc t inlet gr oup . For e xample , consider the c ase of t wo inlet gr oups f or a par ticular pr oblem. The first inlet gr oup consists of w ater and air en tering thr ough the same inlet (a single fac e zone). In this c ase, you would sp ecify an inlet gr oup ID of 1 f or tha t inlet (or inlet gr oup). The sec ond inlet gr oup c onsists of oil and air en tering thr ough the same inlet gr oup , but each uses a diff erent inlet (oil-inlet and air-inlet ) for each phase . In this c ase, you w ould sp ecify the same Inlet G roup ID of 2 f or both of the inlets tha t belong t o the inlet gr oup . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2146Modeling M ultiphase F lows26.3.4.4. Setting the O utlet Gr oup For pr essur e outlet b oundar ies, the Outlet G roup ID is used t o iden tify the diff erent outlets tha t are part of the same outlet gr oup . For instanc e, when b oth phases en ter thr ough the same outlet (single face zone), then those phases ar e par t of one outlet gr oup and y ou w ould set the Outlet G roup ID to 1 f or tha t outlet (or outlet gr oup). In the c ase wher e the same outlet gr oup has separ ate outlets (diff erent fac e zones) f or each phase , then the Outlet G roup ID will b e the same f or each outlet of tha t group . When sp ecifying the outlet gr oup , use the f ollowing guidelines: •Since the Outlet G roup ID is used t o iden tify the outlets of the same outlet gr oup , gener al inf ormation such as Free S urface Level or Bottom L evel should b e the same f or each outlet of the same outlet gr oup . •You should sp ecify a diff erent Outlet G roup ID for each distinc t outlet gr oup . For e xample , consider the c ase of t wo outlet gr oups f or a par ticular pr oblem. The first outlet gr oup consists of w ater and air e xiting fr om the same outlet (a single fac e zone). In this c ase, you w ould specify an outlet numb er of 1 f or tha t outlet (or outlet gr oup). The sec ond outlet gr oup c onsists of oil and air e xiting thr ough the same outlet gr oup , but each uses a diff erent outlet (oil-outlet and air-outlet ) for each phase . In this c ase, you w ould sp ecify the same Outlet G roup ID of 2 for b oth of the outlets tha t belong t o the outlet gr oup . Imp ortant For thr ee-phase flo ws, when all the phases ar e lea ving thr ough the same outlet , the outlet should c onsist only of a single fac e zone . 26.3.4.5. Determining the F ree S urface Level For the appr opriate boundar y, you need t o sp ecify the Free S urface Level value .This par amet er is available f or all r elevant boundar ies, including pr essur e outlet , mass-flo w inlet , and pr essur e inlet. The Free S urface Level, is represen ted b y in Equa tion 18.42 in the Theor y Guide . (26.9) wher e is the p osition v ector of an y point on the fr ee sur face, and is the unit v ector in the dir ection of the f orce of gr avity. Here a hor izontal fr ee sur face tha t is nor mal t o the dir ection of gr avity is as- sumed . We can simply c alcula te the fr ee sur face level in t wo steps: 1.Determine the absolut e value of heigh t from the fr ee sur face to the or igin in the dir ection of gr avity. 2.Apply the c orrect sign based on whether the fr ee sur face level is ab ove or b elow the or igin. If the liquid ’s free sur face level lies ab ove the or igin, then the Free S urface Level is p ositiv e (see Figur e 26.22: Determining the F ree Sur face Level and the B ottom L evel (p.2148 )). Likewise , if the liquid ’s free sur face level lies b elow the or igin, then the Free S urface Level is nega tive. You c an also sp ecify a tr ansien t profiles f or a Free S urface Level for the r elevant op en channel boundar ies as sho wn in the e xample b elow: 2147Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the VOF M odel/********************************************************************* Example UDF that demonstrates transient profile for free surface level **********************************************************************/ #include "udf.h" #define H 1.5 /* Original Free surface level */ #define T0 0.2 /* Time */ DEFINE_TRANSIENT_PROFILE(fs_level, current_time) { real level; if (current_time <= T0) level = H - current_time; else level = H - T0; return level; } 26.3.4.6. Determining the B ottom L evel For the appr opriate boundar y, you need t o sp ecify the Bottom L evel value .This par amet er is a vailable for all r elevant boundar ies, including pr essur e outlet , mass-flo w inlet , and pr essur e inlet. The Bottom Level, is represen ted b y a r elation similar t o Equa tion 18.42 in the Theor y Guide . (26.10) wher e is the p osition v ector of an y point on the b ottom of the channel, and is the unit v ector of gr avity. Here we assume a hor izontal fr ee sur face tha t is nor mal t o the dir ection of gr avity. We can simply c alcula te the b ottom le vel in t wo steps: 1.Determine the absolut e value of depth fr om the b ottom le vel to the or igin in the dir ection of gr avity. 2.Apply the c orrect sign based on whether the b ottom le vel is ab ove or b elow the or igin. If the channel ’s bottom lies ab ove the or igin, then the Bottom L evel is p ositiv e (see Figur e 26.22: De- termining the F ree Sur face Level and the B ottom L evel (p.2148 )). Likewise , if the channel ’s bottom lies below the or igin, then the Bottom L evel is nega tive. Figur e 26.22: Determining the F ree S urface Level and the B ottom L evel You c an also sp ecify a tr ansien t profiles f or a Bottom L evel for the r elevant op en channel b oundar ies. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2148Modeling M ultiphase F lows26.3.4.7. Specifying the Total H eight The t otal heigh t, along with the v elocity, is used as an option f or descr ibing the flo w.The t otal heigh t is giv en as (26.11) wher e is the v elocity magnitude and is the gr avity magnitude . 26.3.4.8. Determining the Velocity M agnitude For pr essur e inlet b oundar ies, input f or Velocity M agnitude is requir ed t o calcula te the d ynamic pressur e being used in the t otal pr essur e calcula tion. Note The pr ovided Velocity M agnitude is not applied t o the b oundar y. 26.3.4.9. Determining the S econdar y Phase for the Inlet In the c ase of a flo w with mor e than t wo phases , for pr essur e inlets and mass-flo w inlets , you c an selec t the desir ed sec ondar y phase fr om the Secondar y Phase f or Inlet drop-do wn b ox. Imp ortant Note tha t only one sec ondar y phase is allo wed t o pass thr ough one inlet gr oup . Consider a pr oblem in volving a thr ee-phase flo w consisting of air as the pr imar y phase , and oil and water as the sec ondar y phases . Consider also tha t ther e ar e two inlet gr oups: •water and air •oil and air For the f ormer inlet gr oup , you w ould cho ose w ater as the sec ondar y phase . For the la tter inlet gr oup , you w ould cho ose oil as the sec ondar y phase (as sho wn in Figur e 26.23: Pressur e Inlet f or Op en Channel F low (p.2150 )). 2149Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the VOF M odelFigur e 26.23: Pressur e Inlet f or Op en C hannel F low 26.3.4.10. Determining the S econdar y Phase for the O utlet For a flo w applic ation with mor e than t wo phases , if y ou selec t Free S urface Level for the Pressur e Specific ation M etho d (in the Pressur e Outlet dialo g box,Multiphase tab), you must also selec t the appr opriate Secondar y Phase f or L evel S pecific ation and sp ecify the Free S urface Level and Bottom Level. See Determining the F ree Sur face Level (p.2147 ) and Determining the B ottom L evel (p.2148 ) for details ab out these par amet ers. For mor e inf ormation ab out the a vailable pr essur e sp ecific ation metho ds, refer to Pressur e Outlet in the Fluent Theor y Guide . The h ydrosta tic pr essur e pr ofile is imp osed in the selec ted sec ondar y phase tha t shar es the in terface with the pr imar y phase . It is assumed tha t other sec ondar y phases will not disturb the imp osed pressur e distr ibution. For e xample , in a thr ee-phase c avitating flo w consisting of air , water, and v apor, the v apor is gener ated in the lo calized r egion adjac ent to mo ving b odies . If the pr essur e outlet b oundar y is sufficien tly far away from the c avitating r egion, then the h ydrosta tic assumption in the w ater phase tha t shar es the interface with air c an b e saf ely imp osed . 26.3.4.11. Choosing the P ressur e Sp ecific ation Metho d For a pr essur e outlet b oundar y, the outlet pr essur e can b e sp ecified in one of thr ee w ays: •by pr escr ibing the fr ee sur face level, such as a h ydrosta tic pr essur e pr ofile (a vailable f or two-phase flo w only) •by sp ecifying the c onstan t pressur e Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2150Modeling M ultiphase F lows•by sp ecifying the neighb oring c ell pr essur e Note You c an also sp ecify a h ydrosta tic pr essur e pr ofile a t the pr essur e outlet f or axisym- metr ic op en channel flo w. However, ther e ar e certain limita tions as not ed in Limita- tions (p.2153 ). Imp ortant This option is not a vailable in the c ase of thr ee-phase flo ws sinc e the pr essur e on the boundar y is tak en fr om the neighb oring c ell. 26.3.4.12. Choosing the D ensit y Int erp olation Metho d For pr oblems in volving sub-cr itical flo w, the f ollowing options e xist f or the Densit y In terpolation Metho d: •From N eighb oring C ell is the default option, wher e the mix ture densit y used in the h ydrosta tic pr ofile is in terpolated using the v olume fr action c alcula ted fr om the neighb oring c ell. Note In some c ases , this metho d ma y cause fr ee sur face oscilla tion near the upstr eam boundar ies.These oscilla tions ar e par ticular ly visible in c ases wher e boundar ies ar e close to the objec t; or if the b oundar y has unstr uctured mesh near the fr ee sur face level. For such c ases , it is r ecommended tha t you use the From F ree S urface Level option under Densit y In terpolation M etho d. •From F ree S urface Level wher e the mix ture densit y used in the h ydrosta tic pr ofile is in terpolated fr om the v olume fr action c alcula ted fr om the fr ee sur face level. •Hybr id wher e the mix ture densit y used in the h ydrosta tic pr ofile is c alcula ted either fr om the From Neighb oring C ell or From F ree S urface Level options , dep ending on the dir ection of flux. This metho d is only a vailable a t a pr essur e outlet. 2151Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the VOF M odelFigur e 26.24: Densit y In terpolation M etho d for Op en C hannel F low 26.3.4.13. Open C hannel F low C ompatibilit y with Velocity Inlet For additional inf ormation, see the f ollowing sec tions: 26.3.4.13.1. Velocity Inlet , Open C hannel F low, Steady-State 26.3.4.13.2. Velocity Inlet , Open C hannel F low,Transien t Open channel flo w compa tibilit y with v elocity inlet is pr ovided in the fr amew ork of the op en channel wave boundar y condition, ther efore, the Open C hannel Wave BC option in the Figur e 26.1: Multiphase Model D ialog Box for the VOF M odel (p.2094 ) must b e enabled first. Velocity inlet c ompa tibilit y allo ws you t o use either a veraged or segr egated v elocity inputs t o mo ving obstacles , water and air , which is not p ossible using either the pr essur e inlet or mass-flo w inlet boundar y conditions . Selec t the Open C hannel Wave BC option in the Velocity Inlet dialo g box. For detailed inf ormation about the v elocity inputs , see Inputs a t Velocity Inlet B oundar ies (p.929). 26.3.4.13.1. Velocity Inlet , Open C hannel F low, Steady -Stat e you must sp ecify (in the Multiphase tab of the Velocity Inlet dialo g box): •Secondar y phase f or the inlet •Free sur face level 26.3.4.13.2. Velocity Inlet , Open C hannel F low,Transient You must set the Wave BC Option to None (in the Multiphase tab of the Velocity Inlet dialo g box). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2152Modeling M ultiphase F lows26.3.4.14. Limitations The f ollowing list summar izes some issues and limita tions asso ciated with the op en channel b oundar y condition. •The c onser vation of the B ernoulli in tegral do es not pr ovide the c onser vation of mass flo w rate for the pressur e boundar y. In the c ase of a c oarser mesh, ther e can b e a signific ant diff erence in mass flo w rate from the ac tual mass flo w rate. For finer meshes , the mass flo w rate comes closer t o the ac tual v alue . So, for pr oblems ha ving c onstan t mass flo w rate, the mass flo w rate boundar y condition is a b etter option. The pr essur e boundar y should b e selec ted when st eady and non-oscilla ting dr ag is the main objec tive. •Specifying the t op b oundar y as the pr essur e outlet c an sometimes lead t o a div ergen t solution. This ma y be due t o the c orner singular ity at the pr essur e boundar y in the air r egion or due t o the inabilit y to sp ecify local flo w dir ection c orrectly if the air en ters thr ough the t op lo cally. •Only the hea vier phase should b e selec ted as the sec ondar y phase . •In the c ase of flo ws with mor e than t wo phases , only one sec ondar y phase is allo wed t o en ter thr ough one inlet gr oup (tha t is, the mix ed inflo w of diff erent sec ondar y phases is not allo wed). •For axisymmetr ic flo w, pressur e and mass-flo w inlets do not supp ort op en channel b oundar y conditions . •Open channel w ave boundar y conditions f or v elocity inlets do not supp ort cases with axisymmetr ic flo w. •Axisymmetr ic op en channel flo w is a vailable f or two phase flo w and the pr essur e outlet b oundar y. •For axisymmetr ic op en channel flo w, the dir ection of gr avity must b e aligned with the dir ection of the axis. 26.3.4.15. Recommendations for S etting Up an O pen C hannel F low P roblem The f ollowing list r epresen ts a list of r ecommenda tions f or solving pr oblems using the op en channel flow b oundar y condition: •In the c ases wher e the inlet gr oup has a diff erent inlet f or each phase of fluid , then the par amet er values (such as Free S urface Level,Bottom L evel, and Mass F low R ate) for each inlet should c orrespond t o all other inlets tha t belong t o the inlet gr oup . •The solution b egins with an estima ted pr essur e pr ofile a t the outlet b oundar y. In gener al, you c an star t the solution b y assuming tha t the le vel of liquid a t the outlet c orresponds to the le vel of liquid a t the inlet. The c onvergenc e and solution time is v ery dep enden t on the initial conditions .When the flo w is c omplet ely sub critical (upstr eam and do wnstr eam), in mar ine applic- ations f or instanc e, the ab ove appr oach is r ecommended . If the final c onditions of the flo w can b e pr edic ted b y other means , the solution time c an b e signi- ficantly r educ ed b y using the pr oper b oundar y condition. •In the c ase of sup er-cr itical flo w at the outlet , you c an use the From N eighb oring C ell option a t the outlet , as it ma y pr ovide b etter convergenc e. •The initializa tion pr ocedur e is v ery critical in the op en channel analy sis. Refer to Recommenda tions f or Open C hannel Initializa tion (p.2164 ). 2153Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the VOF M odel•For the initial stabilit y of the solution, a smaller time st ep is r ecommended .You c an incr ease the time st ep once the solution b ecomes mor e stable . •For flo ws tha t do not mak e a tr ansition fr om sub-cr itical to sup er-cr itical, or vic e-versa, you c an sp eed-up the solution c alcula tion b y sp ecifying the fr equenc y of F roude numb er up dates dur ing r un time b y setting the f ollowing t ext command:solve → set → open-channel-controls . When pr ompt ed, set up the f ollowing par amet er for st eady-sta te flo ws: /solve/set> open-channel-controls Iteration interval for Froude number update [10] When pr ompt ed, set up the f ollowing par amet er for tr ansien t flo ws: /solve/set> open-channel-controls Time step interval for Froude number update [1] •For pur e op en channel flo w applic ations , the inlet and outlet b oundar y conditions ar e controlled b y the Froude numb er. In c ertain c ases , it is p ossible t o imp ose a h ydrosta tic pr ofile a t the outlet without an y Froude numb er dep endenc y.You c an use the f ollowing t ext command:solve → set → open-channel- controls . When pr ompt ed, set up the f ollowing par amet er as sho wn b elow: /solve/set> open-channel-controls Use Froude number independent boundary condition at outlet? [no] yes •Relevant op en channel inputs , along with the F roude numb er, can b e reported using the f ollowing t ext command:define → boundary-conditions → openchannel-threads . •In the c ase of r everse flo w, the pr essur e outlet b oundar y behaves as a pr essur e inlet , and the b oundar y- specific sta tic pr essur e is tak en as the Total P ressur e. In this c ase, the sta tic pr essur e is c alcula ted fr om the t otal pr essur e.You c an use the f ollowing t ext command t o fix the b oundar y-sp ecified sta tic pr essur e, which helps t o suppr ess r eflec tions fr om the pr essur e boundar y for certain c ases:solve → set → open- channel-controls When pr ompt ed, set up the f ollowing par amet er as sho wn b elow: /solve/set> open-channel-controls Use boundary specified static pressure for backflow? [no] yes 26.3.5. Modeling Op en C hannel Wave Boundar y Conditions When mo deling op en channel w ave boundar y conditions , man y of the v ariables tha t are used in op en channel flo w, also e xist f or op en channel w ave boundar y conditions .You ma y ha ve to refer to Modeling Open C hannel F lows (p.2144 ) for inf ormation ab out some of the settings . To use the op en channel w ave boundar y condition, perform the f ollowing: 1.Enable Gravity and set the gr avitational acc eleration fields . Setup → Gener al Gravity → On 2.Enable the Volume of F luid mo del in the Multiphase M odel dialo g box. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2154Modeling M ultiphase F lowsSetup → Models → Multiphase → Edit... 3.Under Formula tion , selec t either Implicit or Explicit . 4.Under VOF S ub-M odels , selec t Open C hannel Wave BC . In or der t o set sp ecific par amet ers f or a par ticular b oundar y for op en channel w ave boundar ies, enable the Open C hannel Wave BC option in the Velocity Inlet boundar y condition dialo g box (Fig- ure 26.25: The Velocity Inlet f or Op en C hannel Wave BC (p.2155 )). Figur e 26.25: The Velocity Inlet f or Op en C hannel Wave BC The default metho d is the Averaged F low S pecific ation M etho d, wher e inputs f or the mo ving obstacle and w ater cur rent are combined .There is no sp ecific tr eatmen t for air v elocity, which is assumed t o be same as the a veraged v elocity. Segr egat ed Velocity Inputs The Segrega ted Velocity Inputs option allo ws you t o pr escr ibe velocity inputs individually f or the moving obstacle , Secondar y phase (t ypic ally w ater), and P rimar y phase (t ypic ally air). 2155Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the VOF M odelFigur e 26.26: Segrega ted Velocity Inputs f or Op en C hannel Wave BC You c an set the mo ving objec t and sec ondar y phase v elocity sp ecific ation metho ds as: •Magnitude and dir ection v ector •Magnitude and nor mal t o boundar y You c an set the pr imar y phase v elocity sp ecific ation metho ds as: •Magnitude and dir ection v ector •Magnitude and nor mal t o boundar y •Power la w and dir ection v ector •Power la w and nor mal t o boundar y Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2156Modeling M ultiphase F lowsPower L aw (26.12) Where is the v ertical distanc e from the instan taneous fr ee sur face level at which the r eference velocity magnitude , is sp ecified . is the v ertical distanc e from the fr ee sur face level at which, velocity must b e estima ted. is the p ower la w coefficien t, which is t ypic ally 0.16 f or an op en sea. Setting Buff er L ayer H eigh t The buff er la yer is assumed t o be the la yer ab ove the fr ee sur face, in which the eff ect of air is not f elt. This option is pr ovided b y assuming tha t the air in the vicinit y of fr ee sur face blo ws with the sp eed of the water and the w aves, so tha t dir ect eff ect of air is not f elt in the w ave pr opaga tion. There ar e two options f or pr oviding the buff er heigh t: 1. Automa tic: the buff er la yer is tak en as the sp ecified fr action of the maximum w ave heigh t. 2. User-defined: you pr ovide the input f or the buff er la yer heigh t. The buff er la yer can also b e defined using the f ollowing t ext command: /solve/set> open-channel-wave-options /solve/set/open-channel-wave-options> set-buffer-layer-ht set-verbosity stokes-wave-variants /solve/set/open-channel-wave-options> set-buffer-layer-ht buffer layer specification method (0 - Automatic, 1 - User-defined) [0] fraction of buffer layer height to maximum wave height [0.02] /solve/set/open-channel-wave-options> set-buffer-layer-ht buffer layer specification method (0 - Automatic, 1 - User-defined) [0] 1 enter the value of buffer layer height [0] In the Momen tum tab of the Velocity Inlet dialo g box, you c an en ter the a veraged flo w velocity, which includes c omp onen ts fr om the flo w cur rent and the mo ving objec t.You c an sp ecify the Averaged Flow S pecific ation M etho d as: •Magnitude and D irection •Magnitude and N ormal t o Boundar y •Comp onen ts In the Multiphase tab ( Figur e 26.27: The Velocity Inlet f or Op en C hannel Wave BC (Explicit F ormula- tion) (p.2158 )), you will sp ecify the f ollowing: 2157Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the VOF M odelFigur e 26.27: The Velocity Inlet f or Op en C hannel Wave BC (E xplicit F ormula tion) •Secondar y Phase f or Inlet specifies the phase t o which the w ave par amet ers ar e applied . In c ase of a three-phase flo w, selec t the c orresponding sec ondar y phase fr om this list. •Wave BC Options of which y ou ha ve a choic e of Shallo w/In termedia te Waves,Shor t Gravity Waves, Shallo w Waves, and None (for calm sea or pur e op en channel flo w pr oblems without w aves). Information about these w aves is a vailable in Open C hannel Wave Boundar y Conditions in the Theor y Guide . Note tha t the shor t gravity waves e xpression is der ived under the assumption of infinit e liquid heigh t. •Free S urface Level is the same definition as f or op en channel flo w, see Modeling Op en C hannel Flows (p.2144 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2158Modeling M ultiphase F lows•Bottom L evel is the same definition as f or op en channel flo w, see Modeling Op en C hannel F lows (p.2144 ), and is v alid only f or shallo w or in termedia te depth w aves.The b ottom le vel is used f or calcula ting the liquid heigh t. •Referenc e Wave Direction is the dir ection of w ave pr opaga tion with z ero wave heading angle .You c an specify the w ave pr opaga tion dir ection as: –Averaged F low D irection : In this c ase, the r eference dir ection is the same as the a veraged flo w dir ection. –Direction Vector –Normal t o Boundar y •Wave M odeling Options det ermines ho w the w aves ar e mo deled in the shallo w/in termedia te and shor t gravity wave regimes .You c an cho ose t o mo del the w aves using either Wave Theor ies or Wave Spectrum. Wave Theor ies is usually selec ted f or simula ting r egular w aves.To simula te random w aves, selec t Wave Spectrum. •Depending on y our choic e of Wave BC Options and Wave M odeling Options , you will need t o sp ecify the w ave par amet ers as descr ibed in the f ollowing sec tions . Shallo w Wave Inputs (p.2159 ) Wave Group Inputs (p.2160 ) Wave Spectrum Inputs (p.2160 ) Shallo w Wave Inputs If you ha ve selec ted Shallo w Waves for Wave BC Options you c an sp ecify the f ollowing settings f or each w ave: Numb er of Waves is the option t o set the numb er of in teracting w aves (default = 1) Ideally , shallo w w aves do not supp ort the pr inciple of sup erposition. The Numb er of Waves option enables in teraction of t wo diff erent waves or igina ting a t unique (non-in terfering) lo cations within the domain. Collision of t wo coun ter-pr opaga ting solitar y waves inside a domain is an e xample of a shallo w w ave in teraction. Wave Theor y of which y ou ha ve a choic e of Fifth Or der S olitar y (the default) and Fifth Or der Cnoidal . Information about the t ypes of w ave theor y is a vailable in Open C hannel Wave Boundar y Conditions in the Theor y Guide . Wave Heigh t is the heigh t diff erence between a w ave crest t o the neighb oring tr ough. Since a solitar y wave do es not ha ve troughs , the w ave heigh t is the distanc e between a w ave crest to mean fr ee sur face level. Wave Length is the distanc e between t wo consecutiv e zero crossings . Since solitar y waves ar e der ived based on the assumption of infinit e wave length, specified w ave length is only used t o estima te the elliptic func tion par amet er for suitabilit y of the w ave theor y, and is not used in c alcula ting w ave par amet ers. 2159Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the VOF M odelInlet O ffset D istanc e is the tr ansla tional distanc e from the r eference point origin in the r eference wave pr opaga tion dir ection. This option is used t o gener ate a w ave from a lo cation other than the r eference frame or igin. For a solitar y wave, the hump is alw ays gener ated a t the lo cation wher e: (26.13) wher e and are spa tial c oordina tes in the r eference wave pr opaga tion dir ection. Wave Heading A ngle is the angle b etween the dir ection of the w avefront and the r eference wave pr opaga tion dir ection, in the plane of the flo w sur face. In 2D , ther e are only t wo possibilities , zero degr ee when the w ave is in the r ef- erence pr opaga tion dir ection, and 180 degr ee when the w ave Is in the dir ection opp osite to the r eference propaga tion dir ection. Wave Gr oup Inputs If you ha ve selec ted Wave Theor ies for Wave M odeling Options you c an sp ecify the f ollowing settings for each w ave: Numb er of Waves is the option t o set the numb er of sup erposed w aves (default = 1) Wave Theor y of which y ou ha ve a choic e of First Or der A iry (the default), Second Or der S tokes,Third Or der S tokes, Four th Or der S tokes, and Fifth Or der S tokes. Information ab out the t ypes of w ave theor y is a vailable in Open C hannel Wave Boundar y Conditions in the Theor y Guide . Wave Heigh t is the heigh t diff erence between a w ave crest t o the neighb oring tr ough. Wave Length is the distanc e between t wo consecutiv e crests , troughs or z ero crossings . Phase D ifferenc e is the phase angle b y which one p eriodic disturbanc e or w avefront lags b ehind or pr ecedes another in time or spac e. Wave Heading A ngle is the angle b etween the dir ection of the w avefront and the r eference wave pr opaga tion dir ection, in the plane of the flo w sur face. In 2D , ther e are only t wo possibilities , zero degr ee when the w ave is in the r ef- erence pr opaga tion dir ection, and 180 degr ee when the w ave Is in the dir ection opp osite to the r eference propaga tion dir ection. Wave Sp ectrum Inputs If you ha ve selec ted Wave Spectrum for Wave M odeling Options you c an sp ecify the f ollowing settings for each w ave: Frequenc y Spectrum M etho d specifies the sp ectrum t o use .You c an selec t Pierson-M osk owitz (appr opriate for fully-de velop ed seas), Jonsw ap (appr opriate for fetch-limit ed seas), or TMA (appr opriate for fetch-limit ed, finit e-depth seas). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2160Modeling M ultiphase F lowsPeak S hap e Paramet er controls the shap e and amplitude of the fr equenc y peak in the Jonsw ap and TMA formula tions .This corresponds t o in Equa tion 18.101 in the Fluent Theor y Guide . Signific ant Wave Heigh t is the mean w ave heigh t of the lar gest 1/3 of w aves.This c orresponds t o in Equa tion 18.100 in the Fluent Theor y Guide . Peak Wave Frequenc y is the w ave frequenc y corresponding t o the highest w ave ener gy.This c orresponds t o in Equa tion 18.100 and Equa tion 18.101 in the Fluent Theor y Guide . can b e expressed in t erms of the p eak w ave period, , as . Minimum/M aximum Wave Frequenc y specify the fr equenc y range f or the sp ectrum. Note tha t the Peak Wave Frequenc y must fall in b etween Minimum Wave Frequenc y and Maximum Wave Frequenc y. Numb er of F requenc y Comp onen ts specifies the numb er of c omp onen ts in to which the fr equenc y sp ectrum is divided . Direction S preading M etho d specifies the metho d to use f or sp ecifying the dir ectional spr eading char acteristics .You c an cho ose Uni- directional (for long-cr ested w aves), Frequenc y Indep enden t Cosine F unc tion (for shor t-crested w aves wher e the dir ectional c omp onen t do es not dep end on fr equenc y), and Frequenc y Dependan t Hyper- bolic F unc tion (for shor t-crested w aves wher e the dir ectional c omp onen t dep ends on fr equenc y). Frequenc y Indep enden t Cosine E xponen t specifies the e xponen t in the F requenc y Indep enden t Cosine F unction f ormula tion. This c orresponds t o in Equa tion 18.105 in the Fluent Theor y Guide . Mean Wave Heading A ngle specifies the pr incipal w ave heading dir ection. Angular S pread specifies the de viation fr om the mean w ave dir ection f or calcula ting the angular r ange . Numb er of A ngular C omp onen ts specifies the numb er of c omp onen ts in to which the angular r ange is divided . The t otal numb er of w ave comp onen ts is the pr oduc t of Numb er of F requenc y Comp onen ts and Numb er of A ngular C omp onen ts. For mo deling r andom w aves, phase diff erences for the individual wave comp onen ts ar e randomly distr ibut ed b etween 0 and 2 π. Note Any change in the input f or Numb er of Wave Comp onen ts will change the v alues of phase diff erence for each c omp onen t.Therefore, it is r ecommended tha t you star t the simula tion fr om a sa ved c ase file af ter setting all the w ave sp ectrum user inputs and that you not change the numb er of w ave comp onen ts dur ing the simula tion. 2161Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the VOF M odel26.3.5.1. Summar y Report and R egime C heck A useful t ext command used t o pr int out a summar y of the op en channel w ave boundar y condition settings is define/boundary-conditions/open-channel-wave-settings .The output will dep end on whether y ou ha ve chosen Wave Theor ies or Wave Spectrum. Sample O utput for Wave Theories /define/boundary-conditions> open-channel-wave-settings Wave Input Analysis for Velocity Inlet : Thread ID = 5 ************************************************************ Wave-1 Analysis ***************************************** Current Settings : ------------------ Wave theory : 5th-order-Stokes , Wave regime = Shallow/Intermediate Wave Height (H) = 0.2160, Wave Length (L) = 1.9400 Liquid Depth (h) = 0.6000, Ursell Number (H*L*L/(h*h*h)) = 3.7636 Mandatory checks for full wave regime within wave breaking limit ----------------------------------------------------------------- Relative Height: H/h = 0.3600 , Maximum theoretical limit = 0.7800 Maximum numerical limit = 0.5500 Relative height within wave breaking limit Wave Steepness: H/L = 0.1113 , Maximum theoretical limit = 0.1420 Stable numerical limit = 0.1000 , Maximum numerical limit = 0.1200 Warning: Wave steepness exceeding the stable numerical limit. Waves could be stable or unstable in this regime. Checks for selected wave theory within wave breaking and stability limit ---------------------------------------------------------------------------- Relative height check H/h = 0.3600 , Min : 0.0000 , Max : 0.5000 Relative height check : successful Wave Steepness check H/L = 0.1113 , Min : 0.0000 , Max : 0.1363 Wave steepness check : successful Ursell Number check Ur = 3.7636 , Min : 0.0000 , Max : 25.0000 Ursell number check : successful Wave regime check h/L = 0.3093 , Min : 0.0600 , Max : 10000.0000 Wave regime check : successful Summary ---------------------- Checks : passed Selected wave theory is appropriate for application. Sample O utput for Wave Sp ectrum Wave Input Analysis for Velocity Inlet : Thread ID = 6 ************************************************************ Wave Spectrum Analysis ***************************************** Current Settings : ------------------ Frequency Spectrum : Jonswap Direction Spreading Method : Unidirectional Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2162Modeling M ultiphase F lowsSignificant Wave Height (Hs) = 5.0000 Peak Wave Frequency (wp) = 1.0000, Peak Time Period (Tp) = 6.2832 Minimum Frequency (wi) = 0.6600, Maximum Frequency (we) = 1.6600 Wave Lengths at Min/Peak/Max frequencies (Li, Lp, Le) = (141.5015, 61.6380, 22.3683) Recommendation: Set the min and max wave frequencies so that most of the wave energy is concentrated in the selected regime of spectrum. - Min frequency = 0.5*Peak frequency - Max frequency = 2.5*Peak frequency Wave Regime Check ---------------------- Wave regime type = Short Gravity (Deep) Information: Validity of short gravity assumption : Liquid Depth > 0.5*Max Wave Length Sea Steepness Check ----------------------- Peak Time Period (Tp) = 6.2832 Zero Upcrossing Time Period (Tz) = 4.7869 Sea Steepness based on Tp (Sp) = 0.0811, Steepness Limit = 0.0667 Sea Steepness based on Tz (Sz) = 0.1398, Steepness Limit = 0.1000 Warning: Sea Steepness based on peak time period exceeding limit. Warning: Sea Steepness based on zero upcrossing time period exceeding limit. Information: High wave steepness of any individual component too could affect the wave pattern, as superposition of wave components is based upon lienar wave theory. Frequency Spectrum Check --------------------------- Peak Time Period to Wave Ht Sqrt Ratio (r = Tp/sqrt(Hs)) = 2.8099 Message: Selection of Jonswap spectrum is appropriate. Recommended value of Peak Shape Parameter for r <= 3.6 : 5.0000 Spectrum Resolution check ---------------------------- Number of frequency components = 50 Number of angular components = 1 Total number of wave components = 50 Information: Higher number of wave components would have adverse effect on speed-up whereas smaller could affect the accuracy by not resolving the spectrum well. Following steps could assist to optimize the number of components 1. Set number of frequency/angular components in boundary condition panel, 2. Set TUI command solve> set> open-channel-wave-verbosity to 2 before initialization, 3. Initialize (It would print Spectrum Energy for each frequency/angle.) 4. Copy the information to plot Sw vs Omega and S_theta vs theta 5. Optimize the number of components after repeating steps 1-4 26.3.5.2. Transient P rofile S upp ort for Wave Inputs ANSY S Fluen t supp orts tr ansien t profiles f or all w ave inputs using user-defined func tions as seen b y the e xample b elow: /*********************************************************************** UDF for defining transient profile wave inputs ************************************************************************/ #include "udf..h" #define H 0.02 /* wave height for both waves : same */ #define LEN1 3. /* wave length for first wave */ #define LEN2 6. /* wave length for second wave*/ 2163Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the VOF M odel#define G 9.81 #define D 10. /* liquid depth */ #define U 1. /* wave current */ #define X 0. /* inlet point */ DEFINE_TRANSIENT_PROFILE(wave_ht, current_time) { real k1 = 2.*M_PI/LEN1; real k2 = 2.*M_PI/LEN2; real w1 = sqrt(G*k1*tanh(k1*D)) + k1*U; real w2 = sqrt(G*k2*tanh(k2*D)) + k2*U; real dk = 0.5*(k1 - k2); real dw = 0.5*(w1 - w2); return (2.*H*cos(dk*X - dw*current_time)); } 26.3.5.3. Alternativ e St okes Wave Theor y Variant Fluen t uses F enton’s formula tion f or S tokes theor ies b y default. For additional inf ormation ab out the current Stokes theor ies f ormula tion, see Stokes Wave Theor ies in the Fluent Theor y Guide .To revert to the old f ormula tion, provided b y Skjebr eia and H endr ickson, use the f ollowing t ext command: /solve/set/open-channel-wave-options> set-buffer-layer-ht set-verbosity stokes-wave-variants /solve/set/open-channel-wave-options> stokes-wave-variants Use Fenton's formulation for Stokes wave theories [yes] no Activating old formulation (Skjelbreia and Hendrickson) for Stokes wave theories. For additional inf ormation on the old f ormula tion, refer to Lin ’s book [67] (p.4008 ). 26.3.6. Rec ommenda tions f or Op en C hannel Initializa tion Onc e you ha ve selec ted either the Open C hannel F low or the Open C hannel Wave BC option in the Multiphase M odel dialo g box, then the Open C hannel Initializa tion M etho d drop-do wn list app ears in the Solution Initializa tion task page . Solution → Initializa tion Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2164Modeling M ultiphase F lowsFigur e 26.28: The S olution Initializa tion Task P age Selec t an inlet z one fr om the Comput e fr om drop-do wn list. You c an no w mak e your selec tion fr om the Open C hannel Initializa tion M etho d drop-do wn list. If only the Open C hannel F low option w as enabled , then y ou only ha ve a choic e of None or Flat. If you enabled Open C hannel Wave BC , then your choic es ar e None ,Flat, or Wavy.The default initializa tion metho d is None . If you initializ e the solution using None , it has no eff ect as it do es not use an y op en channel inf ormation from the selec ted z one .The Open C hannel Initializa tion M etho d comes in to eff ect when y ou selec t either Flat or Wavy. Imp ortant This initializa tion is only v alid f or pr essur e-inlets , pressur e outlets , and mass-flo w inlets f or open channel flo w and v elocity inlets f or op en channel w ave boundar y conditions . If the 2165Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the VOF M odelselec ted inlet z one do es not ha ve either op en channel flo w or op en channel w ave boundar y conditions , ANSY S Fluen t will r eport an er ror message af ter y ou initializ e the flo w with op en channel initializa tion metho d of Flat or Wavy. For op en channel initializa tion fr om the pr essur e outlet b oundar y, the h ydrosta tic pr essur e pr ofile based on the Free S urface Level is pa tched in the domain. The v olume fr action in the domain is patched based on Free S urface Level provided a t the pr essur e outlet b oundar y.To pa tch v elocity and other v ariables , the v alues in the Solution Initializa tion task page will b e used . Imp ortant The pr essur e sp ecific ation metho ds, with the e xception of Free S urface Level, are not supp orted f or op en channel initializa tion fr om the pr essur e outlet b oundar y. Initializa tion will r esult in the v olume fr action, X,Y, and Z v elocities , and pr essur e being pa tched in the domain. The v olume fr action will b e pa tched in the domain based on the fr ee sur face level of the selec ted z one fr om the Comput e fr om list. The v elocities in the domain will b e pa tched assuming the constan t value pr ovided f or the v elocity magnitude in the selec ted z one . Imp ortant If you sp ecify a pr ofile f or the v elocity magnitude or dir ection v ectors, the initializa tion will selec t the v alue f or the v elocity magnitude and dir ection v ectors fr om only one fac e. Therefore the initializa tion ma y be inaccur ate. However, gener ally, open channel inputs f or velocity magnitude and dir ection v ectors ar e constan t. The pr essur e tha t is pa tched is the h ydrosta tic pr essur e based on the fr ee sur face level sp ecified in the selec ted z one . You c an use the f ollowing t ext command f or op en channel aut oma tic initializa tion: solve → initialize → open-channel-auto-init When pr ompt ed, set up the f ollowing par amet ers: boundar y thr ead id Enter the thr ead id f or the b oundar y to be selec ted f or op en channel aut oma tic initializa tion. flat free sur face initializa tion This option is a vailable f or b oth op en channel flo w and op en channel w ave boundar y conditions . wavy free sur face initializa tion This option app ears only f or op en channel w ave boundar y conditions , when fla t free sur face initializa tion is not selec ted. The st eps t o be followed f or op en channel aut oma tic initializa tion ar e 1.Comput e defaults based on v alid op en channel b oundar y thr ead.This st ep is r equir ed f or b etter initializ- ation of turbulenc e par amet ers based on unif orm velocity magnitude . solve → initialize → compute defaults Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2166Modeling M ultiphase F lows2.This w ould pr ovide inf ormation ab out the selec ted b oundar y and t ype of initializa tion. solve → initialize → open-channel-auto-init 3.Initializ e solve → initialize → initialize 26.3.6.1. Reporting P aramet ers for O pen C hannel Wave BC O ption To report values as w ave sp eed, wave frequenc y, and time p eriod for individual w aves dur ing initial- ization, you c an set the f ollowing t ext command: solve → set → open-channel-wave-options → set-verbosity When pr ompt ed t o set Verbosity for reporting of derived wave inputs during initialization , enter 1 as sho wn b elow: Note You c an en ter v alues of 0, 1, or 2. Entering a higher numb er pr ovides mor e inf ormation. /solve/set/open-channel-wave-options> set-verbosity Verbosity for reporting of derived wave inputs during initialization [0] 1 A sample of the r esulting output f or w ave gr oups af ter initializing is sho wn b elow: Wave-1 : Wave Height = 0.0200, Wave Length = 3.0000 Wave Number = 2.0944, Wave Speed = 2.1642, Wave Frequency = 4.5328 Effective parameters: Wave Speed = 3.1642, Wave Frequency = 6.6272, Time Period = 0.9481 Wave-2 : Wave Height = 0.0200, Wave Length = 6.0000 Wave Number = 1.0472, Wave Speed = 3.0607, Wave Frequency = 3.2052 Effective parameters: Wave Speed = 4.0607, Wave Frequency = 4.2524, Time Period = 1.4776 Time Period based on average effective frequency: 1.1550 The r esultan t output f or Shallo w Waves option is sho wn b elow: Wave-1 : Wave Height = 0.2400, Specified Wave Length = 16.0000 Wave Number = 0.5051, Estimated Wave Length = 12.4398 Elliptic Function Parameter (m) : Calculated = 0.9976, Used = 1.0000 Liquid Height = 0.8000, Trough Height = 0.800000 Wave Speed = 3.1868, Wave Frequency = 1.6096 Effective parameters: Wave Speed = 4.1868, Wave Frequency = 2.1147 Time Period based on effective frequency: 2.9712 26.3.7. Numer ical B each Treatmen t for Op en C hannels In certain applic ations , it is desir able t o suppr ess numer ical reflec tion near the outlet b oundar y for wave damp ening .To understand the theor y involved in this applic ation, refer to Numer ical Beach Treatmen t. To include numer ical b each in y our simula tion, perform the f ollowing: 2167Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the VOF M odel1.Enable Gravity and set the gr avitational acc eleration fields . Setup → Gener al Gravity → On 2.Enable the Volume of F luid mo del in the Multiphase M odel dialo g box. Setup → Models → Multiphase → Edit... 3.Under Scheme , selec t either Implicit or Explicit . 4.Selec t Open C hannel F low and/or Open C hannel Wave BC . In or der t o set the numer ical b each par amet ers f or a fluid z one , go t o the Fluid dialo g box (Fig- ure 26.29: The F luid D ialog Box to Enable N umer ical Beach (p.2168 )). Figur e 26.29: The F luid D ialo g Box to Enable N umer ical B each In the Multiphase tab of the Fluid dialo g box, enable the Numer ical B each option and en ter the following: •Beach G roup ID represen ts the c ell z ones shar ing the damping length c ontaining the same input par amet ers. •Multi-D irectional B each helps t o suppr ess the numer ical reflec tions tha t arise fr om multiple op en-channel pressur e outlet b oundar ies.This is desir able while mo deling oblique w aves or when the pr essur e-outlet boundar ies ar e closer t o the z one of in terest. (Only a vailable f or 3D pr oblems .) •Uni-D irectional B each: should b e used t o suppr ess the numer ical reflec tions fr om a single op en channel pressur e outlet. This is the c ase when the flo w is gener ally uni-dir ectional. •Damping Type allo ws you t o cho ose b etween Two Dimensional and One D imensional . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2168Modeling M ultiphase F lows–Two Dimensional is the damping tr eatmen t in the b each and gr avity dir ection. –One dimensional is the damping tr eatmen t in the b each dir ection. •Comput e From Inlet B oundar y is set t o none by default. If ther e are available op en channel b oundar ies (velocity-inlet , pressur e-inlet , and mass-flo w-inlet), boundar y names ar e added t o the dr op-do wn list. If you selec t a b oundar y from the list , the Level Inputs ,Uni-D irectional B each Inputs or Multi-D irectional Beach Inputs in b each dir ection, and Damping Resistanc e values will b e up dated in the in terface.You have the option t o overwrite the up dated inputs with v alues tha t are mor e applic able t o your simula tion. •Level Inputs is only a vailable f or the Two Dimensional damping t ype. –Free S urface Level is the same definition as f or op en channel flo w, see Modeling Op en C hannel Flows (p.2144 ). –Bottom L evel is the same definition as f or op en channel flo w, see Modeling Op en C hannel F lows (p.2144 ). During the aut oma tic c alcula tion fr om the v elocity inlet b oundar y for shor t gravity waves, this par amet er is up dated under some assumptions , as not ed in Solution S trategies (p.2170 ).The b ottom le vel is used for calcula ting the liquid heigh t. Numeric al B each Inputs Numer ical b each is assumed as a r ectangular domain, wher e its end-plane (out er sur face) is an op en channel pr essur e outlet b oundar y and star t-plane is a plane par allel t o a pr essur e outlet. Beach dir ection is assumed as the dir ection nor mal t o a pr essur e outlet. Damping length is the nor mal distanc e between the end and star t plane . Uni-D irectional B each Inputs: X,Y, and Z are the v ector comp onen ts of the b each out ward nor mal (t ypic ally nor mal t o the near est pressur e outlet). The end p oint is c alcula ted b y tak ing the dot pr oduc t of b each dir ection with an y point lying on the end plane . Similar ly, the star t point is c alcula ted as the dot pr oduc t of b each dir ection with any point lying on the star t-plane . Note The aut oma tically c alcula ted v alue of the end p oint is assumed based on the domain extents for all of the c ell z ones . Enter y our o wn v alue if r equir ed. Damping L ength S pecific ation is only a vailable if Open C hannel Wave BC is enabled in the Multiphase M odel dialo g box.There ar e two options y ou c an cho ose fr om: •End P oint and Wave Lengths (default). •End and S tart Points are the limits of the damping z one . Multi-D irectional B each Inputs •Numb er of B each The default is 2, the maximum is 3. •X-D irection 2169Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the VOF M odel•Y-D irection •Z-D irection •End P oint •Damping L ength See Figur e 26.30: Numer ical Beach S ketch (p.2170 ) for a visual r epresen tation of the numer ical b each. Figur e 26.30: Numer ical B each S ketch •Rela tive Velocity Resistanc e Formula tion calcula tes the sour ce term using r elative velocities in the nu- mer ical beach z one when using mo ving/def orming meshes or mo ving r eference frames . •Linear D amping Resistanc e is the r esistanc e per unit time . •Quadr atic D amping Resistanc e is the r esistanc e per unit length. 26.3.7.1. Solution Str ategies Below ar e some helpful k ey points when using the Numer ical B each option: 1.The Comput e from Inlet B oundar y drop-do wn list is a c onvenien t feature as it pr ovides aut oma tic inputs , which y ou should check t o mak e sur e the v alues ar e reasonable . Some of the pr ovided v alues are calcula ted under c ertain assumptions: a.The b ottom le vel, in the c ase of shor t gravity waves, is selec ted in the v elocity inlet dialo g box for op en channel w ave boundar y conditions . Since ther e is no user input f or this par amet er, ANSY S Fluen t calcula tes the b ottom le vel as the v alue of the fr ee sur face level less 2.5 times the wave length. The assumption is tha t the liquid heigh t is 2.5 times the w ave length. b.The aut oma tically c alcula ted v alue of the end p oint is assumed based on the domain e xtents for all of the c ell z ones . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2170Modeling M ultiphase F lows2.For manual inputs of star t and end p oints, you should v erify tha t these p oints ar e calcula ted c orrectly in the b each dir ection. To check f or their v alidit y, subtr acting the star t point from the end p oint should giv e you a p ositiv e value . 3.For manual inputs of Free S urface Level and Bottom L evel, you should v erify tha t these p oints ar e calcula ted c orrectly in the dir ection opp osite to gr avity.To check f or their v alidit y, subtr acting the bottom le vel fr om the fr ee sur face level should giv e you a p ositiv e value . 4.In case y ou cr eate separ ate damping z ones , but the damping length is not sufficien t to suppr ess the w aves, clubbing of the b each c ould b e done b y selec ting the same b each ID f or other c ell z ones . In this c ase, both the c ell z ones w ould shar e the same inf ormation. 5.In case of separ ate damping z ones (without clubbing), you should v erify tha t the damping length is mor e than or equal t o the sp ecified numb er of w ave lengths f or the c alcula tion of the star t point. 6.Damping r esistanc e should b e chosen c arefully as t oo much or t oo little damping c ould aff ect the wave pr ofiles in a no-damping z one .The Comput e From Inlet B oundar y option aut oma tically popula tes the v alues f or damping r esistanc es based on analytic al correlations f or w ave ener gy. However, you ma y need t o fur ther tune these v alues f or certain c ases if the c omput ed v alues ar e found t o be unsuitable . 7.Steep damping a t the b eginning of the damping z one c ould aff ect the w ave pr ofile just b efore the damping z one . 8.It is r ecommended tha t you use a c oarse mesh in the damping z one with incr eased c oarseness t o- wards the end of the damping z one . 26.3.8. Defining the P hases f or the VOF M odel Instr uctions f or sp ecifying the nec essar y inf ormation f or the pr imar y and sec ondar y phases and their interaction in a VOF c alcula tion ar e pr ovided b elow. Imp ortant In gener al, you c an sp ecify the pr imar y and sec ondar y phases whiche ver w ay you pr efer. It is a go od idea, esp ecially in mor e complic ated pr oblems , to consider ho w your choic e will affect the ease of pr oblem setup . For e xample , if y ou ar e planning t o pa tch an initial v olume fraction of 1 f or one phase in a p ortion of the domain, it ma y be mor e convenien t to mak e that phase a sec ondar y phase . Also, if one of the phases is a c ompr essible ideal gas , it is recommended tha t you sp ecify it as the pr imar y phase t o impr ove solution stabilit y. 26.3.8.1. Defining the P rimar y Phase To define the pr imar y phase in a VOF c alcula tion, perform the f ollowing st eps: 1.Selec t phase-1 in the Phases list. 2.Click Edit... to op en the Primar y Phase dialo g box (Figur e 26.31: The P rimar y Phase D ialog Box (p.2172 )). 2171Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the VOF M odelFigur e 26.31: The P rimar y Phase D ialo g Box 3.In the Primar y Phase dialo g box, enter a Name for the phase . 4.Specify which ma terial the phase c ontains b y cho osing the appr opriate ma terial in the Phase M aterial drop-do wn list. 5.Define the ma terial pr operties f or the Phase M aterial. a.Click Edit..., and the Edit M aterial dialo g box will op en. b.In the Edit M aterial dialo g box, check the pr operties, and mo dify them if nec essar y. (See Physical Properties (p.1079 ) for gener al inf ormation ab out setting ma terial pr operties,Modeling C ompr essible Flows (p.2102 ) for sp ecific inf ormation r elated t o compr essible VOF c alcula tions , and Modeling S olidi- fication/M elting (p.2181 ) for sp ecific inf ormation r elated t o melting/solidific ation VOF c alcula tions .) Imp ortant If you mak e changes t o the pr operties, rememb er to click Change before closing the Edit M aterial dialo g box. 6.Click OK in the Primar y Phase dialo g box. 26.3.8.2. Defining a S econdar y Phase To define a sec ondar y phase in a VOF c alcula tion, perform the f ollowing st eps: 1.Selec t the phase (f or e xample ,phase-2 ) in the Phases list. 2.Click Edit... to op en the Secondar y Phase dialo g box (Figur e 26.32: The S econdar y Phase D ialog Box for the VOF M odel (p.2173 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2172Modeling M ultiphase F lowsFigur e 26.32: The S econdar y Phase D ialo g Box for the VOF M odel 3.In the Secondar y Phase dialo g box, enter a Name for the phase . 4.Specify which ma terial the phase c ontains b y cho osing the appr opriate ma terial in the Phase M aterial drop-do wn list. 5.Define the ma terial pr operties f or the Phase M aterial, following the pr ocedur e outlined ab ove for setting the ma terial pr operties f or the pr imar y phase . 6.Click OK in the Secondar y Phase dialo g box. 26.3.8.3. Including S urface Tension and A dhesion E ffec ts As discussed in When Sur face Tension E ffects A re Imp ortant in the Theor y Guide , the imp ortanc e of surface tension eff ects dep ends on the v alue of the c apillar y numb er, Ca (defined b y Equa tion 18.32 in the Theor y Guide ), or the Weber numb er,We (defined b y Equa tion 18.33 in the Theor y Guide ). Surface tension eff ects can b e neglec ted if C a or We . If you w ant to include the eff ects of sur face tension along the in terface between one or mor e pairs of phases , as descr ibed in Surface Tension and A dhesion in the Theor y Guide , right-click Phase In ter- actions (under the Setup/M odels/M ultiphase tree it em) and selec t Edit... to op en the Phase In ter- action D ialog Box (p.3451 ) (Figur e 26.33: The P hase In teraction D ialog Box (Sur face Tension Tab) (p.2174 )). Setup → Models → Multiphase → Phase In teractions Edit... 2173Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the VOF M odelFigur e 26.33: The P hase In teraction D ialo g Box (S urface Tension Tab) Perform the f ollowing st eps t o mo del sur face tension (and , if appr opriate, include adhesion) eff ects along the in terface between one or mor e pairs of phases: 1.In the Surface Tension tab , enable the Surface Tension F orce M odeling option t o include the sur face tension metho d. Note Make sur e you sp ecify the Surface Tension C oefficien ts as constan t or user-defined . If none is selec ted, then Surface Tension F orce M odeling will aut oma tically b e disabled . 2.Selec t the sur face tension metho d tha t is most applic able t o your c ase.You c an cho ose b etween Con- tinuum S urface Force and Continuum S urface Stress. Information ab out each of the metho ds is de- scribed in Surface Tension in the Theor y Guide . 3.For each pair of phases b etween which y ou w ant to include the eff ects of sur face tension, specify an input for the sur face tension c oefficien ts using one of the f ollowing options: •Constan t Value •Temp erature-dep enden t polynomial, piec ewise p olynomial, or piec ewise linear Note These options ar e available while mo deling ener gy. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2174Modeling M ultiphase F lows•User-defined sur face tension c oefficien t Note This c an b e defined as a func tion of an y spac e variable or time . See Surface Tension and A dhesion in the Theor y Guide for mor e inf ormation on sur face tension, and the Fluen t Customiza tion M anual for mor e inf ormation on user-defined func tions . All sur face tension c oefficien ts ar e equal t o 0 b y default , represen ting no sur face tension eff ects along the interface between the t wo phases . Imp ortant For c alcula tions in volving sur face tension, it is r ecommended tha t you also tur n on the Implicit B ody Force treatmen t for the Body Force Formula tion in the Multiphase Model dialo g box.This tr eatmen t impr oves solution c onvergenc e by acc oun ting f or the par tial equilibr ium of the pr essur e gr adien t and sur face tension f orces in the mo- men tum equa tions . See Including B ody Forces (p.2104 ) for details . 4.If you w ant to include w all adhesion, enable the Wall A dhesion option and then sp ecify the c ontact angle a t each w all as a b oundar y condition (as descr ibed in Steps f or S etting B oundar y Conditions (p.2124 )). 5.If you w ant to include jump adhesion, enable the Jump A dhesion option. When Jump A dhesion is en- abled , you will need t o sp ecify the c ontact angle a t the p orous jump in the Porous Jump dialo g box (as descr ibed in Defining M ultiphase C ell Z one and B oundar y Conditions (p.2124 )).The c ontact angle sp ecific- ation and measur emen t for jump adhesion is similar t o tha t of w all adhesion (as e xplained in st ep 3 above). Imp ortant Jump adhesion only supp orts the c ell based smo othing option f or sur face tension. When the Jump A dhesion option is enabled in the Phase In teraction dialo g box, the correct settings ar e aut oma tically set f or sur face tension. To view the sur face tension settings , use the solve/set/surface-tension text command . Note The f ollowing limita tions e xist: •When the Wall A dhesion and Jump A dhesion options ar e enabled , you must sp ecify a nonz ero surface tension c oefficien t. •Jump A dhesion is not a vailable with the Continuum S urface Stress mo del. •The Continuum S urface Stress mo del and the Jump A dhesion option ar e not a vailable with the Level S et option. 2175Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the VOF M odelSeveral sur face tension options ar e pr ovided thr ough the t ext user in terface (TUI) using the solve/set/surface-tension command : solve → set → surface-tension The surface-tension command pr ompts y ou f or the f ollowing inf ormation: •whether y ou r equir e no de-based smo othing The default v alue is yes , indic ating tha t no de-based smo othing will b e used . Note tha t if y ou ar e reading in a c ase tha t was cr eated in v ersions pr ior t o ANSY S Fluen t 13, then c ell-based smo othing will b e used b y default. •the numb er of smo othings The default v alue is 1. A higher v alue c an b e used in c ase of t etrahedr al and tr iangular meshes in order t o reduc e an y spur ious v elocities . •the smo othing r elaxa tion fac tor The default is 1.This is useful in the c ases wher e volume fr action smo othing c auses a pr oblem (f or example , liquid en ters thr ough the inlet with w all adhesion on). •whether y ou w ant to use v olume fr action gr adien ts at the no des f or cur vature calcula tions With this option, ANSY S Fluen t uses v olume fr action gr adien ts dir ectly fr om the no des t o calcula te the cur vature for sur face tension f orces.The default is yes which pr oduces b etter results with surface tension c ompar ed t o gr adien ts tha t are calcula ted a t the c ell c enters. Imp ortant •Note tha t the c alcula tion of sur face tension eff ects will b e mor e accur ate if y ou use a quadr ilat- eral or he xahedr al mesh in the ar ea(s) of the c omputa tional domain wher e sur face tension is signific ant. If you c annot use a quadr ilateral or he xahedr al mesh f or the en tire domain, then you should use a h ybrid mesh, with quadr ilaterals or he xahedr a in the aff ected ar eas. ANSY S Fluen t uses no de based smo othing f or smo othed v olume fr action and no de based gradien ts for smo othed cur vature calcula tion t o pr ovide b etter accur acy and r obustness . •Pressur e jump c aused b y the sur face tension is disc ontinuous in na ture, and also it ac ts lo cally at the in terface.These numer ical difficulties ar e overcome in an appr oxima te manner b y con- sider ing the smo othed distr ibution of the v olume fr action field within the finit e interfacial width. Smoothing pr ocedur es, in gener al, are mesh dep enden t.Therefore, the amoun t and nature of the smo othing pr ocedur e could ha ve a signific ant eff ect on the r esults f or sur face tension c ases . 26.3.8.4. Discr etizing Using the P hase L ocaliz ed C ompr essiv e Scheme Most of the in terface captur ing or tr acking schemes , which ar e common in lit erature, can simula te either diffused in terface mo deling or shar p in terface mo deling .There ar e a numb er of applic ations wher e you ma y be in terested in mo deling diffused and shar p in terfaces in diff erent regimes , which results in the need f or a unique discr etiza tion pr ocedur e to handle such applic ations . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2176Modeling M ultiphase F lowsBelow ar e some e xamples of such applic ations: •Air bubble r ise in w ater-solid slur ry: Diffused in terface mo deling is r equir ed f or the w ater and solid , and shar p in terface mo deling f or the air bubble is desir able . A shar pening scheme w ould c ause undesir able eff ects for the mo deling of the diffused in terface between w ater and solids and a diffusiv e scheme w ould not b e able t o main tain the shar p in terface for bubble r ising in the slur ry. •Evaporation/c ondensa tion in a tank par tially filled with w ater and b eing hea ted a t the b ottom: Diffused in terface mo deling is r equir ed f or the liquid-v apor and shar p in terface mo deling f or the water-air r egime is desir able . A shar pening scheme , would not b e able t o simula te the diffused phe- nomena of e vaporation/c ondensa tion f or the liquid- v apor phase and a diffusiv e scheme w ould not be able t o main tain the shar p in terface between w ater and air . •Air jet p enetr ating thr ough la yer of liquids: You ma y be interested in diffused jet mo deling and shar p in terface mo deling b etween the liquid la yers. A shar pening scheme w ould not b e able t o main tain the c ontinuous air str eam and a diffusiv e scheme w ould not b e able t o main tain the shar p interfaces b etween the la yers of liquids . Using the M odified HRIC and C ompr essiv e schemes f or such applic ations w ould r esult in the HRIC scheme pr oducing undesir able shar pening of the disp ersed phases and undesir able diffusion of the continuous phases , wher eas the C ompr essiv e scheme w ould pr oduce undesir able shar pening of the disp ersed phases . Therefore, the phase lo calized c ompr essiv e scheme is par ticular ly useful in c ases wher e the desir able behavior is such tha t you ha ve diffused mo deling of disp ersed phases and shar p mo deling of c ontinu- ous phases . In ANSY S Fluen t, diffusiv e and an ti-diffusiv e discr etiza tion pr ocedur es c an b e used acr oss the distinc t interfaces, which shar e a pair of phases .This func tionalit y is pr ovided thr ough the c om- pressiv e discr etiza tion scheme , wher e the degr ee of diffusion or shar pness is c ontrolled thr ough the value of the slop e limit ers.The theor y used is descr ibed in The C ompr essiv e Scheme and In terface- Model-based Variants. 2177Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the VOF M odelFigur e 26.34: The P hase In teraction D ialo g Box for the VOF M odel (D iscr etiza tion Tab) To use the phase lo calized c ompr essiv e scheme , perform the f ollowing st eps: 1.Click the Discr etiza tion tab . Note The Discr etiza tion tab is a vailable f or the VOF mo del, Mixture multiphase mo del, and Euler ian multiphase mo del with Mulit-F luid VOF only when the Phase L ocaliz ed Discr etiza tion option is enabled in the Interface M odeling Options dialo g box. (Inter- face M odeling Type (p.2097 )). 2.Enable Phase L ocaliz ed C ompr essiv e Scheme . Imp ortant When this option is enabled , the Compr essiv e spa tial discr etiza tion scheme is aut oma t- ically selec ted f or the Volume F raction in the Solution M etho ds dialo g box. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2178Modeling M ultiphase F lows3.For each pair of phases , specify the v alue of the slop e limit er.You c an en ter a v alue of 0, 1, or 2, or an y value b etween 0 and 2. Refer to Table 26.11: Slope Limit er D iscretiza tion Scheme (p.2179 ) to equa te each value of the slop e limit er with a discr etiza tion scheme . Table 26.11: Slope Limit er D iscr etiza tion Scheme Scheme Slope Limit er Value first or der up wind 0 second or der r econstr uction b ounded b y the global minimum/maximum of the v olume fr action1 compr essiv e 2 blended: wher e a v alue b etween 0 and 1 means blending of the first or der and sec ond or der and a v alue b etween 1 and 2 means blending of the second or der and c ompr essiv e scheme and When using the Phase L ocaliz ed C ompr essiv e Scheme , not e the f ollowing: •The minimum limit f or the slop e limit er is 0, wher eas the maximum is 2. •The slop e limit er can b e interpreted as the degr ee of c ompr ession/an ti-diffusion, wher e 0 demonstr ates the minimum c ompr ession and 2 demonstr ates the maximum c ompr ession. •For in terfaces shar ing the diffused phases , a slop e limit er value of 2 should not b e used . A value between 0 and 1 is r ecommended . •For in terfaces shar ing the c ontinuous phases , any value b etween 0 and 2 c an b e used dep ending on the applic ation. •For in terfaces shar ing the c ontinuous and diffused phases , any value b etween 0 and 2 c an b e used based on the applic ation. •If you w ant variable discr etiza tion b ehavior f or an in terface between t wo phases , you c an do so via the DEFINE_PROPERTY user-defined func tion. Note –If the in terface has a tr ansition fr om shar p to diffused mo deling , you should not e xper- ienc e an y pr oblems . –If the in terface has a tr ansition fr om diffused t o shar p mo deling , this tr ansition should be smo oth b y gr adually v arying the v alue of the slop e limit er within some tr ansition zone . 26.3.9. Setting Time-D ependen t Paramet ers f or the E xplicit Volume F raction Formula tion If you ar e using the Explicit volume fr action f ormula tion in ANSY S Fluen t, an e xplicit solution f or the volume fr action is obtained either onc e each time st ep or onc e each it eration, dep ending up on y our inputs t o the mo del. You also ha ve control o ver the time st ep used f or the v olume fr action c alcula tion. 2179Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the VOF M odelYou c an acc ess the c ontrols f or the v olume fr action fr om the Multiphase M odel D ialog Box (p.3248 ) by click ing Expert Options ... There ar e two inputs f or the time-dep enden t calcula tion f or the VOF mo del: Sub-T ime S tep C alcula tion M etho d When ANSY S Fluen t uses the Explicit formula tion, the time st ep used f or the v olume fr action c alcula tion will not b e the same as the time st ep used f or the r est of the tr ansp ort equa tions . ANSY S Fluen t will r efine the time st ep f or VOF aut oma tically, based on y our input f or the maximum Cour ant Numb er allo wed near the fr ee sur face.The C ourant numb er is a dimensionless numb er tha t compar es the time st ep in a calcula tion t o the char acteristic time of tr ansit of a fluid elemen t acr oss a c ontrol volume . The char acteristic tr ansit time f or a fluid elemen t acr oss the c ontrol volume r epresen ts the time taken b y the fluid t o empt y out of the c ell.This tr ansit time is tak en as the smallest of such time in the r egion near the fluid in terface. A sub time st ep, for use in the VOF c alcula tions , is c omput ed based on this char acteristic time , and the maximum allo wed Cour ant Numb er set in the Multiphase Model D ialog Box (p.3248 ). For e xample , if the maximum allo wable Cour ant Numb er is 0.25 (de- fault), the c omput ed sub time st ep will ha ve a maximum v alue equal t o a quar ter of the minimum transit time f or an y cell near the in terface. In Fluen t, the sub time st ep siz e for VOF c alcula tions c an b e comput ed using the f ollowing options: •Velocity Based: The sub time st ep is estima ted b y the c ell siz e and the fluid v elocity nor mal t o the in terface: (26.14) wher e, is the C ourant Numb er, is the fluid v elocity, and is the c ell siz e. •Flux B ased : For this option, the sub time st ep is estima ted based on the c ell v olume and the summa tion of out going flux es in the c ell: (26.15) wher e, is the C ourant Numb er, is the v olume , and are the out going flux es. •Flux A veraged :The sub time st ep siz e is estima ted b y volumetr ic averaging the c alcula tions of the Flux B ased metho d for the neighb oring c ells. •Hybr id:This is the default metho d for c alcula ting sub time st ep siz e.The sub time st ep siz e is estima ted b y blending the Velocity Based and Flux A veraged calcula tion metho ds. Note The Flux B ased calcula tion metho d is the most c onser vative sub-time st ep siz e estima tion, while the Velocity Based calcula tion is the most aggr essiv e.Flux A ver- aged and Hybr id metho ds fall in b etween f or most c ases . Aggressiv e sub time st ep c alcula tion metho ds gener ally sa ve time dur ing in terface reconstr uction. However, the aggr essiv e metho d can lead t o incr eased numb er of iterations due t o lar ger tr ansien t errors b eing in troduced while in tegrating o ver the sub time st eps f or the in terface reconstr uction. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2180Modeling M ultiphase F lowsSolve VOF E very Iteration By default , ANSY S Fluen t will solv e the v olume fr action equa tion(s) onc e for each time st ep.This means that the c onvective flux c oefficien ts app earing in the other tr ansp ort equa tions will not b e complet ely updated each it eration, sinc e the v olume fr action fields will not change fr om it eration t o iteration. When ANSY S Fluen t solv es these equa tions e very iteration, the c onvective flux c oefficien ts in the other tr ansp ort equa tions will b e up dated based on the up dated v olume fr actions a t each it eration. This choic e is the less stable of the t wo, and r equir es mor e computa tional eff ort per time st ep than the default choic e. Imp ortant If you ar e using sliding meshes , or d ynamic meshes with la yering and/or r emeshing , using the Solve VOF E very Iteration option will yield mor e accur ate results , although at a gr eater computa tional c ost. 26.3.10. Modeling S olidific ation/M elting If you ar e including melting or solidific ation in y our VOF c alcula tion, not e the f ollowing: •It is p ossible t o mo del melting or solidific ation in a single phase or in multiple phases . •For phases tha t are not melting or solidifying , you must set the la tent hea t ( ), liquidus t emp erature ( ), and solidus t emp erature ( ) to zero. See Modeling S olidific ation and M elting (p.2321 ) for mor e inf ormation ab out melting and solidific ation. 26.3.11. Using the VOF-t o-DPM M odel Transition f or D ispersion of Liquid in Gas For the analy sis of disp ersion of liquid in gas , two pr incipal multiphase flo w metho dolo gies c an b e applied: •In the E uler-Lagr ange appr oach, discr ete dr oplets ar e tracked thr ough the domain. The par ticle tr acker uses ph ysical pr operties of individual dr oplets in or der t o acc oun t for the e xchange of mass , momen tum, heat, species (and so on) with the c ontinuous phase .The gas v olume displac emen t by the dr oplets is ignor ed. This appr oach is r elatively c omputa tionally ine xpensiv e because it allo ws the mesh t o be coarser than the size of a dr oplet. The sec ondar y br eakup c an b e mo deled r elatively accur ately using k nown br eakup models . However, in the dense r egion of a spr ay, simula tion accur acy ma y suff er fr om neglec ting the v olume displac emen t. Also, in r egions wher e the spr ay do es not c onsist of discr ete spher ical dr oplets , special models must b e used t o pr edic t the pr imar y br eakup of the initial c ontiguous liquid jet. These mo dels must be der ived fr om e xperimen tal da ta based up on the op erating c onditions f or each injec tor. •In the v olume-of-fluid ( VOF) appr oach, the v olume fr action of the liquid is st ored in each c ell.The gas-liquid interface can b e tracked b y explicit discr etiza tion schemes , such as geometr ic reconstr uction. The VOF model r equir es a much higher mesh r esolution and much smaller time st eps.The phase b oundar y around every dr oplet must b e resolv ed b y a mesh tha t is signific antly finer than the finest dr oplets .This allo ws for better pr edic tions of the pr imar y br eakup.The v olume displac emen t is inher ently acc oun ted f or, which can b e imp ortant for the dense r egion of the disp ersed spr ay. However, this metho d is e xpensiv e and r equir es large HPC r esour ces. 2181Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the VOF M odelANSY S Fluen t provides the c apabilit y to combine the t wo appr oaches descr ibed ab ove by using a VOF- to-DPM mo del tr ansition mechanism. The initial jet and pr imar y br eakup ar e pr edic ted using the VOF model on a sufficien tly fine mesh, while the v oluminous dilut e region of the disp ersed spr ay is simula ted by the DPM. The VOF-t o-DPM mo del tr ansition algor ithm aut oma tically finds c ompac t liquid masses that ha ve detached fr om the liquid c ore in the VOF solution. It then assesses their eligibilit y for the VOF-t o-DPM mo del tr ansition. If the liquid lump sa tisfies user-sp ecified cr iteria, such as lump siz e and aspher icity (tha t is, relative or nor maliz ed de viation fr om the shap e of a p erfect spher e), it is r emo ved from the r esolv ed liquid in the VOF simula tion and c onverted t o a par ticle par cel in the Lagr angian formula tion. Any local solution-adaptiv e (such as hanging-no de) mesh r efinemen t used t o resolv e the gas-liquid in terface is aut oma tically r everted, so tha t the Lagr angian par ticle par cel can b e plac ed in a single lar ge c ell. If the v olume of a liquid lump is much lar ger than the v olume of the c oarsened mesh c ell, then the lump will b e converted in to as man y Lagr angian par ticle par cels as the numb er of cells spanned b y the lump such tha t the v olume of each par cel will b e equal t o its c orresponding c ell volume . In ear ly stages af ter the c onversion, the gr oup of par ticle par cels r epresen ting the liquid droplet will tr avel together , but as the y pr oceed thr ough the domain, their pa ths ma y gr adually div erge. Converting liquid lumps t o Lagr angian par cels do es not imp ose v olume displac emen t on the c ontinuous- phase VOF flo w simula tion. In or der t o avoid spur ious momen tum sour ces, a volume of gas with the same v olume as the liquid lump is cr eated in the VOF simula tion t o main tain the v olume c onser vation. The mass sour ce tha t is equiv alen t to the mass of the gas v olume will aff ect the o verall mass balanc e. This appr oach c an b e used f or simula ting liquid a tomiza tion in gas turbines , internal c ombustion engines , and other similar applic ations . Such simula tions usually r equir e high spa tial and t emp oral resolution t o captur e all the r elevant details of a pr imar y atomiza tion pr ocess of a liquid jet. Resour ce limita tions will r estrict this appr oach t o detailed analy ses in r egions near the no zzle . For the c omplet e simula tion of a spr ay sy stem or pr ocess, it is r e- commended tha t all inf ormation ab out the Lagr angian DPM par ticle par cels b e captur ed and tr ansf erred into a separ ate simula tion tha t only uses the E uler/Lagr ange appr oach b ecause it allo ws a c oarser mesh and lar ger time st eps t o be used . This c an b e achie ved, for e xample , by using DPM par ticle sampling on either a cut plane or the outlet boundar y of the domain of the detailed VOF-t o-DPM simula tion. For unst eady par ticle tr acking, the sampling f eature wr ites inf ormation in to a file f or e very par ticle par cel tha t crosses the sampling plane or b oundar y.The file c an then b e used as an unst eady injec tion file f or another unst eady par ticle tracking simula tion. ANSY S Fluen t will r ecreate each par ticle par cel at the same lo cation and instanc e in simula ted time (flow-time in the injec tion file). An alt ernative to using DPM par ticle sampling f or cr eating such a file is t o use the VOF-t o-DPM built- in func tionalit y as descr ibed b elow. If you pr ovide a filename , the solv er will wr ite a new file c ontaining information f or each liquid lump tha t has b een c onverted.The file has the same f ormat as a DPM sample file f or unst eady par ticle tr acking.Therefore, it c an b e read in to a separ ate DPM simula tion as an unst eady injec tion file . 26.3.11.1. Limitations on Using the VOF-to-DPM Mo del Transition •The VOF-t o-DPM mo del tr ansition f eature cannot b e used with the f ollowing: –Steady-sta te flo w –Multi-fluid VOF –Steady DPM par ticle tr acking Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2182Modeling M ultiphase F lows–The L evel Set mo del •The iden tification of individual lumps and the c alcula tion of the lump pr operties do not acc oun t for sp ecial boundar y conditions such as symmetr y and p eriodicit y (including p eriodic non-c onformal in terfaces). A liquid lump tha t touches a symmetr y boundar y is tr eated as if it w as a ttached t o a w all. A lump tha t inter- sects a p eriodic b oundar y is tr eated as multiple indep enden t lumps . In b oth c ases , the v alues c alcula ted for the lump pr operties, par ticular ly the aspher icity, will b e aff ected. Imp ortant The VOF-t o-DPM mo del tr ansition mechanism is a vailable only f or 3D c ases . 26.3.11.2. Setting up the VOF-to-DPM Mo del Transition To use the VOF-t o-DPM M odel Transition c apabilit y, follow the st eps b elow: 1.When gener ating the mesh f or y our analy sis, avoid high-asp ect-ratio c ells. Adjust the mesh r esolution so tha t four or fiv e levels of hanging-no de r efinemen t will b e sufficien t for resolving the finest str uctures when y ou ar e using the VOF c alcula tion. 2.If appr opriate, define the d ynamic solution-adaptiv e (hanging-no de) mesh r efinemen t. Domain → Adapt → Refine/C oarsen... For e xample , if y ou just w ant to mak e sur e tha t the phase b oundar y is r esolv ed with the highest possible mesh r esolution, you c an use c ell r egist ers tha t apply the Curvature metho d to the phase volume fr action in or der t o coarsen all c ells with a v alue b elow 1.e-10 and r efine all c ells with a value ab ove 1.e-08. Make sur e to selec t Dynamic A daption and use a small Frequenc y (such as 1 or 2). If the r esolution of the initial mesh is not unif orm, you c an sp ecify a minimum c ell v olume in the Adaption C ontrols dialo g box in or der t o avoid e xcessiv ely small c ells (and ther efore high CFL numb ers), or when multiphase-sp ecific time st epping is used , to avoid e xcessiv ely small time- steps. If a sufficien t numb er of r efinemen t levels is sp ecified , the adapt ed mesh a t the liquid/gas interface will ha ve little v ariation in c ell v olume , regar dless of the lo cal resolution in the initial mesh. If you use hanging no des t o cr eate the initial mesh, mak e sur e tha t you use the p olyhedr al un- structured mesh adaption (PUMA) f or the d ynamic solution-adaptiv e mesh r efinemen t, because the c onventional mesh adaption will sk ip two cell la yers on the c oarse side of the hanging no des. To ac tivate PUMA, use the f ollowing t ext command: mesh/adapt/set/method 2 3.In the Discr ete Phase M odel dialo g box, selec t Unstead y Particle Track ing. Physics → Models → Discr ete Phase ... 4.Create a DPM injec tion of an y type as usual and sp ecify a v ery lar ge v alue f or Start Time .This will guar- antee tha t no par ticles will b e injec ted a t the sp ecified lo cation. Setup → Models → Discr ete Phase → Injec tions New... 2183Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the VOF M odel5.In the Multiphase M odel dialo g box, configur e the f ollowing settings . Physics → Models → Multiphase ... Value Setting Tab (Selec ted) Volume of F luid Model Explicit Formula tion Volume F raction Paramet ers Sharp Type Interface M odeling (Selec ted) Implicit B ody Force Body Force Formula tion 6.In the Phase In teraction dialo g box in the Surface Tension tab , define the c orrect sur face tension f or the gas-liquid b oundar y. Setup → Models → Multiphase → Phase In teractions Edit... 7.In the Solution M etho ds task page , configur e the f ollowing solution par amet ers. Solution → Solution → Metho ds... Value Setting Group B ox PISO Scheme Pressur e-Velocity Coupling Geo-Rec onstr uct Volume F raction Spatial D iscretiza tion PREST O! or Body Force Weigh tedPressur e 8.If you selec ted PISO for the Pressur e-Velocity Coupling scheme , incr ease the Pressur e and Momen tum Under-R elaxa tion F actors t o values close t o 1 (f or e xample , 0.98) in the Solution C ontrols task page . Solution → Controls → Controls... 9.In the Phase In teraction dialo g box, in the Mod.Trans'on tab , define VOF-t o-DPM mo del tr ansition. Setup → Models → Multiphase → Phase In teractions Edit... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2184Modeling M ultiphase F lowsa.Specify the Numb er of M odel Transition M echanisms . b.For each mechanism, selec t the liquid phase fr om the Phase t o be Converted drop-do wn list and also the gas phase fr om the Volume-balancing E uler ian P hase drop-do wn lists . Lagr angian par ticle par cels do not ha ve an y volume displac emen t eff ect on an y VOF phase . Therefore, in or der t o main tain v olume c onser vation in the VOF solution, when liquid fr om the VOF solution is c onverted in to one or mor e Lagr angian par ticle par cel(s), an equal v olume of the selec ted gas phase is plac ed in to the VOF solution as a r eplac emen t for the c onverted liquid . c.For each pair of phases with mo del tr ansition, selec t vof-t o-dpm from the Mechanism drop-do wn list. 2185Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the VOF M odelFigur e 26.35: The VOF-t o-DPM P aramet ers D ialo g Box d.In the VOF-t o-DPM P aramet ers dialo g box tha t op ens aut oma tically, specify the par amet ers f or the model tr ansition: Frequenc y (do e very N time st eps) specifies the fr equenc y at which the VOF-t o-DPM mo del tr ansition mechanism is r un. Injec tion is a list of a vailable injec tions . Make sur e you selec t the injec tion tha t you cr eated ear lier f or the VOD-t o-DPM mo del tr ansition. All newly cr eated par ticle par cels will b e assigned t o the selec ted injec tion. Coarsen the M esh when L umps ar e Converted specifies whether the mesh should b e coarsened when a liquid lump is c onverted t o a DPM particle par cel and r emo ved fr om the VOF solution. The c oarsening is achie ved b y reverting all previously d ynamic ally added mesh r efinemen ts.This option is selec ted b y default and r ecom- mended . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2186Modeling M ultiphase F lowsSplit an y DPM P arcel tha t Exceeds the C ell Volume b y Factor specifies a r atio used f or det ermining the numb er of DPM par cels in to which the liquid lump is divided . If the liquid lump v olume do es not e xceed the v olume of the c oarsened c ell multiplied by this fac tor, the lump is c onverted in to one par cel containing one par ticle . Other wise , the lump is split in to as man y par cels as ther e are cells c overed b y the or iginal liquid lump .To conser ve mass , the numb er of par ticles p er par cel is r educ ed fr om unit y such tha t the sum of all par cels resulting fr om the split r epresen ts exactly the mass of the or iginal liquid lump . The splitting of a single lump in to multiple par ticle par cels ma y be needed if ther e is a r isk that DPM sour ce terms ma y cause instabilities in the c ontinuous phase flo w solution. This may happ en f or c ases with e vaporation or b oiling and a fine back ground mesh. As long as y ou do not enc oun ter an y stabilit y issues in the c ontinuous phase flo w solution, you c an set a v ery high v alue f or this fac tor in or der t o pr event lumps fr om splitting in to multiple par cels. However, if the fac tor is set r elatively lo w, a lump ma y split in to multiple parcels.These par cels ar e mutually indep enden t and ther efore ma y disp erse . Splitting parcels do es not change the global siz e distr ibution, but the y ma y aff ect the spa tial distr i- bution of par cels of diff erent siz es thr oughout the spr ay. VOF L umps C onversion Requir emen ts contains par amet ers f or sp ecifying c onversion eligibilit y limits . Volume-E quiv alen t Spher e Diamet er R ange sets the Minimum and Maximum diamet er values f or a v olume-equiv alen t spher e. Liquid droplets f ound in the VOF solution whose v olume is outside this r ange will not b e converted to Lagr angian par ticle par cels. Upper Limits of A spher icity as C alcula ted b y Maximum A spher icity by Radius S td. Dev. specifies the maximum aspher icity calcula ted fr om the nor maliz ed r adius standar d de vi- ation. This quan tity is c alcula ted f or e very liquid lump f ound in the VOF solution as f ollows. For e very fac et of the lump sur face (gas-liquid phase in terface), the distanc e between the facet center and the lump c enter of gr avity is c alcula ted.The individual distanc e values are weigh ted b y the siz e of the individual lump b oundar y fac et.Their standar d de viation is comput ed and then nor maliz ed b y the a verage r adius . This quan tity is z ero for p erfect spher es and incr easingly gr eater than z ero the mor e the shap e de viates fr om a spher e. All dr oplets f or which the aspher icity value is below the sp ecified maximum ma y be aut oma tically elec ted f or c onversion. The default v alue f or Maximum A spher icity by Radius S td. Dev. is 0.5. Maximum A spher icity by Radius-S urface Or tho gonalit y specifies the maximum aspher icity calcula ted fr om the a verage r adius-sur face or thogon- ality.This quan tity is c alcula ted f or e very liquid lump f ound in the VOF solution as f ollows. For e very fac et of the lump sur face (gas-liquid phase in terface), a vector fr om the lump's center of gr avity to the c enter of the lump b oundar y fac et is c omput ed.This v ector is normaliz ed and then used in a dot pr oduc t with the fac et unit nor mal t o yield a measur e of a r elative or thogonalit y ranging fr om 0 t o 1. For a p erfect spher e, the v alue w ould all be 1. A fac et ar ea-w eigh ted a verage of these v alues is then subtr acted fr om 1 t o obtain the aspher icity value . For almost spher ical dr oplets , this quan tity is signific antly closer t o 0 than the standar d de viation-based aspher icity. For mor e dr astic ally non-spher ical lumps , it 2187Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the VOF M odelproduces v alues c ompar able t o those obtained with the standar d de viation-based aspher icity.The default v alue f or Maximum A spher icity by Radius-S urface Or tho- gonalit y is 0.5. Lump C onversion Transcr ipt F ile N ame (empt y for none) (optional) sp ecifies a name f or the file wher e ANSY S Fluen t will sa ve the DPM par ticle v ariables corresponding t o each VOF lump tha t is c onverted.The file c ontains one line f or each c onverted lump , regar dless of whether a lump w as converted in to one or multiple DPM par cels.The file is written in the same f ormat tha t is used f or par ticle sampling (see Sampling of Trajec tories (p.2054 )). As with an y sample file wr itten b y unst eady par ticle tr acking, this file c an b e used as an unst eady injec tion file .This mak es it p ossible t o calcula te the small dense r egion of a spr ay using the VOF-t o-DPM mo del tr ansition mechanism and the much lar ger dilut e region in a pur e DPM c alcula tion tha t uses the lump c onversion tr anscr ipt as an injec tion file . For better control o ver the numb er of the numer ical par ticle par cels, the injec tion file c an b e run thr ough the file r educ tion t ool as descr ibed in Data R educ tion of S amples (p.2059 ). If you use a DEFINE_DPM_OUTPUT UDF t o wr ite the par ticle sampling file , the same UDF will b e used t o wr ite the lump c onversion tr anscr ipt file .The UDF giv es y ou c ontrol o ver the file c ontent and it e ven allo ws you t o mo dify the DPM par ticle par cels gener ated fr om the liquid lumps dur ing the VOF-t o-DPM mo del tr ansition. For details , see DEFINE_DPM_OUTPUT in the Fluent C ustomization Manual . You c an use the DEFINE_DPM_OUTPUT UDF t o add additional DPM v ariables t o the output file in e xtra columns . If you then use tha t lump c onversion tr anscr ipt file as an un- steady injec tion file in a separ ate simula tion, you c an use a DEFINE_DPM_INJEC- TION_INIT UDF t o read the additional c olumns and use the da ta to initializ e the addi- tional DPM v ariables . For details , see DEFINE_DPM_INJECTION_INIT in the Fluent Customization Manual . Use this M echanism f or L ump P ostpr ocessing when selec ted, ANSY S Fluen t uses the mechanism settings f or the c alcula tion of the p ostpr ocessing lump det ection quan tities . See Postpr ocessing f or VOF-t o-DPM M odel Transition C alcula- tions (p.2188 ) for inf ormation ab out p ostpr ocessing lump det ection quan tities . The liquid lumps ha ving dimensions within the sp ecified lump diamet er range and falling b elow both the aspher icity criteria will b e elec ted f or c onversion t o DPM par cels. In or der t o see t ypic al aspher icity values f or the dr oplets in y our simula tion, you c an, for e x- ample , create contour plots of the aspher icity field func tions on an iso-sur face of a v olume fraction of 0.5. 26.3.11.3. Postpr ocessing for VOF-to-DPM Mo del Transition C alculations The f ollowing additional p ostpr ocessing v ariables will b ecome a vailable f or p ostpr ocessing under the Lump D etection... categor y: •Lump ID •Lump D iamet er •Lump D ensit y •Lump A sph. by Rad. Std. Dev. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2188Modeling M ultiphase F lows•Lump A sph. by Or tho gonalit y •Lump X, Y, Z C oordina te •Lump X, Y, Z Velocity •Lump Temp erature When the ener gy equa tion is enabled , the f ollowing additional v ariables ar e available f or p ostpr ocessing under the Lump D etection... categor y: •Lump Temp erature •Lump E nthalp y •Lump P ressur e 26.4. Setting U p the M ixture M odel For back ground inf ormation ab out the mix ture mo del and the limita tions tha t apply , refer to Overview in the Theor y Guide . For additional inf ormation, see the f ollowing sec tions: 26.4.1. Defining the P hases f or the M ixture Model 26.4.2. Including M ixture Drift Force 26.4.3. Including C avitation E ffects 26.4.4. Including S emi-M echanistic B oiling 26.4.1. Defining the P hases f or the M ixture M odel Instr uctions f or sp ecifying the nec essar y inf ormation f or the pr imar y and sec ondar y phases and their interaction f or a mix ture mo del c alcula tion ar e pr ovided b elow. 26.4.1.1. Defining the P rimar y Phase The pr ocedur e for defining the pr imar y phase in a mix ture mo del c alcula tion is the same as f or a VOF calcula tion. See Defining the P rimar y Phase (p.2171 ) for details . 26.4.1.2. Defining a N on-Gr anular S econdar y Phase To define a non-gr anular (tha t is, liquid or v apor) sec ondar y phase in a mix ture multiphase c alcula tion, perform the f ollowing st eps: 1.Selec t the phase (f or e xample ,phase-2 ) in the Phases list. 2.Click Edit... to op en the Secondar y Phase D ialog Box (p.3444 ) (Figur e 26.36: The S econdar y Phase D ialog Box for the M ixture Model (p.2190 )). 2189Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the M ixture ModelFigur e 26.36: The S econdar y Phase D ialo g Box for the M ixture M odel 3.In the Secondar y Phase dialo g box, enter a Name for the phase . 4.Specify which ma terial the phase c ontains b y cho osing the appr opriate ma terial in the Phase M aterial drop-do wn list. 5.Define the ma terial pr operties f or the Phase M aterial, following the same pr ocedur e you used t o set the ma terial pr operties f or the pr imar y phase (see Defining the P rimar y Phase (p.2171 )). For a par ticula te phase (which must b e plac ed in the fluid ma terials c ategor y, as men tioned in Steps f or U sing a M ultiphase Model (p.2091 )), you need t o sp ecify only the densit y; you c an ignor e the v alues f or the other pr operties, sinc e the y will not b e used . 6.In the Properties group b ox, specify the Diamet er of the bubbles , droplets , or par ticles of this phase ( in Equa tion 18.166 in the Theor y Guide ).You c an sp ecify a c onstan t value , or use a user-defined func tion. See the Fluen t Customiza tion M anual for details ab out user-defined func tions . Note tha t when you ar e using the mix ture mo del without slip v elocity, this input is a char acteristic length sc ale. 7.Click OK in the Secondar y Phase dialo g box. 26.4.1.3. Defining a Gr anular S econdar y Phase To define a gr anular (tha t is, par ticula te) sec ondar y phase in a mix ture mo del multiphase c alcula tion, perform the f ollowing st eps: 1.Selec t the phase (f or e xample ,phase-2 ) in the Phases list. 2.Click Edit... to op en the Secondar y Phase D ialog Box (p.3444 ) (Figur e 26.37: The S econdar y Phase D ialog Box for a G ranular P hase U sing the M ixture Model (p.2191 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2190Modeling M ultiphase F lowsFigur e 26.37: The S econdar y Phase D ialo g Box for a G ranular P hase U sing the M ixture M odel 3.In the Secondar y Phase dialo g box, enter a Name for the phase . 4.Specify which ma terial the phase c ontains b y cho osing the appr opriate ma terial in the Phase M aterial drop-do wn list. 5.Define the ma terial pr operties f or the Phase M aterial, following the same pr ocedur e you used t o set the ma terial pr operties f or the pr imar y phase (see Defining the P rimar y Phase (p.2171 )). For a gr anular phase (which must b e plac ed in the fluid ma terials c ategor y, as men tioned in Steps f or U sing a M ultiphase Model (p.2091 )), you need t o sp ecify only the densit y; you c an ignor e the v alues f or the other pr operties, sinc e the y will not b e used . Imp ortant Note tha t all pr operties f or gr anular flo ws can b e defined b y user-defined func tions (UDFs). See the Fluen t Customiza tion M anual for details ab out user-defined func tions . 6.Enable the Granular option. 7.In the Properties group b ox, specify the f ollowing pr operties of the par ticles of this phase: 2191Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the M ixture ModelDiamet er specifies the diamet er of the par ticles .You c an selec t constan t in the dr op-do wn list and sp ecify a constan t value , or selec t user-defined to use a user-defined func tion. See the Fluen t Customiza tion Manual for details ab out user-defined func tions . Granular Visc osit y specifies the metho d for computing the k inetic ( ) and c ollisional ( ) comp onen ts of the granular visc osity (Equa tion 18.139 in the Fluent Theor y Guide ). Selec ting constan t,syamlal-obr ien (Equa tion 18.141 in the Fluent Theor y Guide ), or gidasp ow (Equa tion 18.142 in the Fluent Theor y Guide ) will use these e xpressions f or the k inetic p ortion of the visc osity and will c alcula te the c ollisional portion of the visc osity from Equa tion 18.140 in the Fluent Theor y Guide . Alternatively, you c an selec t user-defined to use a user-defined func tion. Note tha t if y ou selec t user-defined , your user-defined func tion must include b oth the k inetic p ortion and the c ollisional p ortion of the visc osity in the v alue it retur ns. Frictional P ressur e specifies the pr essur e gr adien t term, , in the gr anular-phase momen tum equa tion. Choose none to exclude fr ictional pr essur e from y our c alcula tion, johnson-et-al to apply Equa tion 18.333 in the Theor y Guide ,syamlal-obr ien to apply Equa tion 18.245 in the Theor y Guide ,based-kt gf, wher e the fr ictional pr essur e is defined b y the k inetic theor y [29] (p.4006 ).The solids pr essur e tends to a lar ge v alue near the pack ing limit , dep ending on the mo del selec ted f or the r adial distr ibution func tion. You must ho ok a user-defined func tion when selec ting the user-defined option. See the Fluen t Customiza tion M anual for inf ormation on ho oking a UDF . Frictional M odulus is defined as (26.16) with , which is the der ived option. You c an also sp ecify a user-defined func tion f or the frictional mo dulus . Friction P ack ing Limit specifies a thr eshold v olume fr action a t which the fr ictional r egime b ecomes dominan t.The default value is 0.61. Granular Temp erature specifies t emp erature for the solids phase and is pr oportional t o the k inetic ener gy of the r andom motion of the par ticles . Choose either the algebr aic, the constan t, or user-defined option. Solids P ressur e specifies the pr essur e gr adien t term, , in the gr anular-phase momen tum equa tion. Choose either the lun-et-al , the syamlal-obr ien, the ma-ahmadi , or the user-defined option. Radial D istribution specifies a c orrection fac tor tha t mo difies the pr obabilit y of c ollisions b etween gr ains when the solid granular phase b ecomes dense . Choose either the lun-et-al , the syamlal-obr ien, the ma-ahmadi , the arastoopour, or a user-defined option. Elasticit y M odulus is defined as Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2192Modeling M ultiphase F lows(26.17) with . Choose either the der ived or user-defined options . Pack ing Limit specifies the maximum v olume fr action f or the gr anular phase . For mono disp ersed spher es, the pack ing limit is ab out 0.63, which is the default v alue in ANSY S Fluen t. In p olydisp ersed c ases , however, smaller spher es c an fill the small gaps b etween lar ger spher es, so y ou ma y need t o incr ease the maximum pack ing limit. 8.Click OK in the Secondar y Phase dialo g box. 26.4.1.4. Defining the Int erfacial A rea C onc entr ation via the Transp ort Equation If you w ant to solv e the tr ansp ort equa tion f or in terfacial ar ea c oncentration of the sec ondar y phase in the mix ture mo del ( Interfacial A rea C oncentration in the Fluent Theor y Guide , perform the f ollowing steps: 1.Selec t the phase (f or e xample ,phase-2 ) in the Phases list. 2.Click Edit... to op en the Secondar y Phase D ialog Box (p.3444 ) (Figur e 26.38: The S econdar y Phase D ialog Box Displa ying the In terfacial A rea C oncentration S ettings (p.2194 )). 2193Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the M ixture ModelFigur e 26.38: The S econdar y Phase D ialo g Box Displa ying the In terfacial A rea C onc entration Settings 3.In the Secondar y Phase dialo g box, enter a Name for the phase . 4.Specify which ma terial the phase c ontains b y cho osing the appr opriate ma terial in the Phase M aterial drop-do wn list. 5.Define the ma terial pr operties f or the Phase M aterial. 6.Enable the Interfacial A rea C onc entration option. Make sur e the Granular option is disabled f or the Interfacial A rea C onc entration option t o be visible in the in terface. 7.In the Properties group b ox, specify the f ollowing pr operties of the par ticles of this phase: Diamet er specifies the diamet er of the par ticles or bubbles .You c an selec t constan t in the dr op-do wn list and specify a c onstan t value , or selec t user-defined to use a user-defined func tion. See the Fluen t Cus- tomiza tion M anual for details ab out user-defined func tions .The Diamet er recommended setting is saut er-mean , allo wing f or the eff ects of the in terfacial ar ea c oncentration v alues t o be consider ed for mass , momen tum and hea t transf er acr oss the in terface between phases . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2194Modeling M ultiphase F lowsSurface Tension specifies the sur face tension a t the liquid-air in terface.You c an selec t either the hibik i-ishii or the ishii-k im mo del. Coalesc enc e Kernel and Br eak age K ernel allows you t o sp ecify the c oalesc ence and br eakage k ernels .You c an selec t none ,constan t,hibik i- ishii ,ishii-k im,yao-mor el, or user-defined .The thr ee options ,hibik i-ishii ,ishii-k im and yao-mor el are descr ibed in detail in Interfacial A rea C oncentration in the Theor y Guide . In addition t o sp ecifying the hibik i-ishii ,ishii-k im, and yao-mor el as the c oalesc ence and breakage k ernels , you c an also tune the pr operties of the thr ee mo dels b y using the /define/phases/iac-expert/hibiki-ishii-model ,/define/phases/iac- expert/ishii-kim-model , and /define/phases/iac-expert/yao-morel-model text commands . For each of the thr ee mo dels y ou c an sp ecify the par amet ers list ed in Table 26.12: Paramet ers for the C oalesc ence and B reakage Ker nels (p.2195 ) Table 26.12: Paramet ers f or the C oalesc enc e and Br eak age K ernels Yao-M orel M odel Ishii-K im M odel Hibik i-Ishii Coefficient K_c1 Coefficient Crc Coefficient Gamma_c Coefficient K_c3 Coefficient Cwe Coefficient K_c Coefficient K_b1 Coefficient C Coefficient Gamma_b alpha_max Coefficient Cti Coefficient K_b alpha_max alpha_max These v alues ar e discussed in gr eater detail in Interfacial A rea C oncentration in the Theor y Guide . Nuclea tion R ate is a sour ce term for the in terfacial ar ea c oncentration tha t mo dels the r ate of f ormation of the disp ersed phase .You c an cho ose fr om constan t or user-defined . Critical Weber N umb er will need t o be sp ecified if y ou selec ted ishii-k im or yao-mor el for the Break age K ernel. Dissipa tion F unc tion gives y ou the option t o cho ose the f ormula which c alcula tes the dissipa tion r ate used in the hibik i- ishii and ishii-k im mo dels .You c an cho ose amongst constan t,wu-ishii-k im,fluen t-ke, and user- defined for the dissipa tion func tion. The wu-ishii-k im option uses a simple algebr aic c orrelation f or : (26.18) wher e and 2195Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the M ixture Modelwher e , , , and are the mix ture densit y, mix ture velocity, mix ture molecular visc osity, and h ydraulic diamet er of the flo w pa th. When y ou selec t the wu-ishii-k im mo del, you will set an additional input f or Hydraulic D ia- met er. Hydraulic D iamet er is the v alue used in Equa tion 26.18 (p.2195 ), should y ou use the wu-ishii-k im formula tion. Min/M ax D iamet er are the limits of the bubble diamet ers. Note When solving a st eady-sta te pr oblem, the pr eferred setting f or the Under-Relaxa tion Factor is 1.0, as the in terfacial ar ea equa tion f or the b oiling mo dels is cur rently under-r e- laxed using a lo cally defined pseudo-time st ep. If you w ant extra explicit under-r elaxa tion, you ma y set the v alue of the Under-Relaxa tion F actor to less than one , this ma y be done only in c ase of ser ious c onvergenc e pr oblems with the in terfacial ar ea tr ansp ort equa tion. To impr ove convergenc e you c an swit ch t o a pseudo-time st ep f or the in terfacial ar ea concentration only , using the define/phases/iac-e xpert/iac-pseudo-time-st ep text com- mand and set the lo cal pseudo-time t o less than 1. 26.4.1.5. Defining the A lgebr aic Int erfacial A rea C onc entr ation If you ha ve chosen not t o solv e the tr ansp ort equa tion f or In terfacial A rea C oncentration ( Defining the In terfacial A rea C oncentration via the Transp ort Equa tion (p.2193 )), then y ou c an selec t an algeb- raic mo del t o estima te the in terfacial ar ea fr om the sec ondar y phase diamet er sp ecified in the Sec- ondar y Phase D ialog Box (p.3444 ).To cho ose an algebr aic in terfacial ar ea mo del p erform these st eps. 1.In the tr ee, right-click Phase In teractions (under Setup/M odels/M ultiphase ) and selec t Edit... to op en the Phase In teraction dialo g box. 2.In the Interfacial A rea tab , selec t the desir ed algebr aic mo del f or the Interfacial A rea. Note the f ollowing regar ding the a vailable choic es: ia-symmetr ic considers b oth the pr imar y and sec ondar y phase v olume fr actions in estima ting the in terfacial ar ea. ia-gr adien t considers the v olume fr action gr adien t at the in terface between t wo phases in estima ting the in ter- facial ar ea. user-defined See DEFINE_EXCHANGE_PROPERTY in the Fluen t Customiza tion M anual . In addition t o these mo dels , ANSY S Fluen t provides the G radien t-Symmetr ic mo del, which is a vailable via the t ext user in terface.You c an use the f ollowing t ext commands t o enable this mo del: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2196Modeling M ultiphase F lowssolve/set/multiphase-numerics/heat-mass-transfer/area-density/ia-grad- sym? switch to ia-grad-symmetric option? [yes] yes See Algebr aic M odels in the Fluent Theor y Guide for details ab out the theor y behind algebr aic in terfacial area mo dels . 26.4.1.6. Defining D rag B etween P hases For mix ture multiphase flo ws with slip v elocity, you c an sp ecify the dr ag func tion t o be used in the calcula tion. The func tions a vailable her e ar e a subset of those discussed in Defining the P hases f or the E uler ian M odel (p.2209 ). See Relative (Slip) Velocity and the D rift Velocity in the Theor y Guide for mor e inf ormation. To sp ecify dr ag la ws, click Interaction... to op en the Phase In teraction D ialog Box (p.3451 ) (Fig- ure 26.39: The P hase In teraction D ialog Box for the M ixture M odel (D rag Tab) (p.2197 )), and then click the Drag tab . Figur e 26.39: The P hase In teraction D ialo g Box for the M ixture M odel (D rag Tab) 26.4.1.7. Defining the Slip Velocity If you ar e solving f or slip v elocities dur ing the mix ture calcula tion, and y ou w ant to mo dify the slip velocity definition, click Interaction... to op en the Phase In teraction D ialog Box (p.3451 ) (Fig- ure 26.40: The P hase In teraction D ialog Box for the M ixture M odel ( SlipTab) (p.2198 )), and then click the Slip tab . 2197Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the M ixture ModelFigur e 26.40: The P hase In teraction D ialo g Box for the M ixture M odel ( SlipTab) Under Slip Velocity, you c an sp ecify the slip v elocity func tion f or each sec ondar y phase with r espect to the pr imar y phase b y cho osing the appr opriate item in the adjac ent drop-do wn list. •Selec t maninnen-et-al (the default) t o use the algebr aic slip metho d of M anninen et al. [73] (p.4009 ), de- scribed in Relative (Slip) Velocity and the D rift Velocity in the Theor y Guide . •Selec t none if the sec ondar y phase has the same v elocity as the pr imar y phase (tha t is, no slip v elocity). •Selec t user-defined to use a user-defined func tion f or the slip v elocity. See the Fluen t Customiza tion Manual for details . 26.4.1.8. Including S urface Tension and Wall A dhesion E ffec ts You c an include the eff ects of sur face tension along the in terface between one or mor e pairs of phases as descr ibed in Including Sur face Tension and A dhesion E ffects (p.2173 ). For mor e inf ormation ab out the theor etical back ground , see Surface Tension and A dhesion in the Fluent Theor y Guide . Note •The sur face tension option in r ecommended f or cases with shar p/disp ersed in terface mo deling type. •Jump adhesion is not supp orted with the M ixture Multiphase mo del. 26.4.2. Including M ixture Drift Force If you ar e solving f or slip v elocity and using one of the turbulenc e mo dels in y our M ixture multiphase calcula tion, you c an also include the eff ects of the slip v elocity on the momen tum and turbulenc e equa tions .To include these eff ects, enable Mixture D rift Force in the Viscous M odel D ialog Box (p.3253 ). The turbulen t disp ersion eff ect will b e included in the slip v elocity equa tion ( Equa tion 18.135 in the Fluent Theor y Guide ). Note tha t the inclusion of these t erms c an slo w do wn c onvergenc e notic eably . If you ar e lo oking f or additional accur acy, you ma y want to comput e a solution first without these Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2198Modeling M ultiphase F lowssour ces, and then c ontinue the c alcula tion with these t erms included . In most c ases these t erms c an be neglec ted. 26.4.3. Including C avita tion E ffects For mix ture mo del c alcula tions , it is p ossible t o include the eff ects of c avitation, using ANSY S Fluen t’s cavitation mo dels descr ibed in Cavitation M odels in the Theor y Guide . To enable the S inghal et al. cavitation mo del, use the solve/set/expert text command and answ er yes to use Singhal-et-al cavitation model? .The Singhal-E t-Al Cavita tion M odel option will no w b e visible in the Phase In teraction dialo g box, under the Mass tab . Enable this option t o include the S inghal et al. cavitation mo del. You will sp ecify thr ee par amet ers t o be used in the c alcula tion of mass tr ansf er due t o cavitation. Set the Vaporization P ressur e, the Surface Tension C oefficien t, and the Non-C ondensable G as M ass Fraction .The default v alue of is 3540 P a, the v aporization pr essur e for w ater a t ambien t temp er- ature. Note tha t and the sur face tension ar e pr operties of the liquid , dep ending mainly on t emp er- ature.Non-C ondensable G as M ass F raction is the mass fr action of dissolv ed gases , which dep ends on the pur ity of the liquid . When multiple sp ecies ar e included in one or mor e sec ondar y phases , or the hea t transf er due t o phase change must b e tak en in to acc oun t, the mass tr ansf er mechanism must b e defined before enabling the c avitation mo del. It ma y be not ed, however, tha t for c avitation pr oblems , at least two mass tr ansf er mechanisms ar e defined: •mass tr ansf er fr om liquid t o vapor. •mass tr ansf er fr om v apor to liquid . To enable and set up the Schner r-Sauer and Zwart-Gerb er-B elamr i cavitation mo dels , refer to Including Mass Transf er E ffects (p.2109 ). 26.4.4. Including S emi-M echanistic B oiling 26.4.4.1. Overview and Limitations for the S emi-Mechanistic B oiling Mo del The semi-mechanistic b oiling mo del c an b e used only with the f ollowing mo dels and c onditions: •Mixture multiphase •Turbulen t kinetic ener gy-based mo dels (such as - or - ) •Activated gr avity along with z ero op erating densit y •Surface tension c oefficien t (sp ecified in the Phase In teraction dialo g box) •Boiling w alls with either t emp erature or c onjuga te hea t transf er b oundar y conditions Note If your c ase has a b oiling w all with hea t flux b oundar y condition, you c an add a small thick ness of solid and apply hea t flux t o the solid b oundar y.Thus y ou will b e able t o 2199Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the M ixture Modelapply hea t flux b oundar y condition indir ectly a t the b oiling w all thr ough c onjuga te hea t transf er b oundar y condition. •Binar y mix tures with the fix ed mix ture comp osition only (pseudo-fluid appr oach). All the pr operties and saturation da ta for the pseudo-fluid must b e pr ovided acc ording t o the mix ture fix ed c omp osition. For the theor etical back ground on the semi-mechanistic b oiling mo del, see Semi-M echanistic B oiling Model in the Fluent Theor y Guide . 26.4.4.2. Using the S emi-Mechanistic B oiling Mo del To use the semi-mechanistic b oiling mo del, follow the st eps b elow: 1.In the Phase In teraction dialo g box, in the Mass tab , specify the Numb er of M ass Transf er M echanisms and then selec t the liquid and v apor phases in the From P hase and To Phase drop-do wn lists , respectively. 2.Selec t evaporation-c ondensa tion from the Mechanism drop-do wn list. 3.In the Evaporation-C ondensa tion M odel dialo g box tha t op ens, selec t Semi-M echanistic as the Boiling Model. The Evaporation-C ondensa tion M odel dialo g box expands t o reveal additional Boiling P aramet- ers. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2200Modeling M ultiphase F lowsFigur e 26.41: The E vaporation-C ondensa tion M odel D ialo g Box Note For the Semi-M echanistic boiling mo del, the Saturation Temp erature can b e only specified using either the tabular-pt-sa t or tabular-ptl-sa t option. 4.In the Boiling P aramet ers group b ox, specify the f ollowing par amet ers: Bulk Temp erature is a t emp erature of bulk fluid a way from the w all.Typic ally, the inlet t emp erature of the c oolan t is used as the bulk t emp erature. Length Sc ale is used in the c alcula tion of the r eference Reynolds numb er. It is t ypic ally tak en t o be the h ydraulic diamet er. 5.To acc ess additional b oiling settings f or ad vanced c ontrol, selec t Boiling M odel A dvanc ed S ettings to reveal mor e options . 6.In the Boiling M odel Ref erenc e Quan tities group b ox, you c an sp ecify the f ollowing: 2201Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the M ixture ModelReferenc e Velocity is the v elocity of the fluid a way from a hea ted w all a t some r eference location. This quan tity is used to calcula te the r eference Reynolds numb er in Equa tion 18.550 in the Fluent Theor y Guide .You can cho ose one of the f ollowing sp ecific ation metho ds: ystar-dep enden t (default) c alcula tes the r eference velocity away from the b oiling w all a t = 250 using standar d wall func tions f or turbulenc e. Here, is a nor maliz ed w all distanc e.You c an adjust its v alue in the Ystar F ar field . constan t specifies a c onstan t value f or the r eference velocity. user-defined uses a user-defined func tion f or the r eference velocity calcula tion. Referenc e Temp erature is the t emp erature of fluid a way from a hea ted w all a t some r eference location ( in Equa tion 18.550 in the Fluent Theor y Guide ). Fluid pr operties used f or the r eference Reynolds numb er computa tion are calcula ted a t the r eference temp erature.You c an cho ose one of the f ollowing sp ecific ation metho ds: bulk-t emp erature (default) tak es the r eference temp erature from a user-defined Bulk Temp erature value . ystar-dep enden t calcula tes the r eference temp erature at =250 using standar d wall func tions f or turbulenc e. In this c ase, a value sp ecified f or Bulk Temp erature serves as the minimum r eference temp erature. user-defined uses a user-defined func tion f or the r eference temp erature calcula tion. 7.In the Boiling M etho ds group b ox, you c an selec t: Chen (default) c alcula tes the b oiling hea t flux as a w eigh ted sup erposition of single-phase hea t flux (f orced convective) and nuclea te boiling hea t flux. See Semi-M echanistic B oiling M odel in the Fluent Theor y Guide for details ab out this metho d. User-D efined uses a fr amew ork pr ovided b y ANSY S Fluen t to ho ok user-defined c orrelations f or all of the r elevant inputs . 8.Enter the v alue f or the Power L aw S uperposition C onstan t ( in Equa tion 18.538 in the Fluent Theor y Guide ).This c onstan t is used t o blend single phase and nuclea te boiling hea t transf er coefficien ts based on asympt otic p ower la w.The default v alue is 2. The t ypic al range is fr om 1 t o 3. 9.In the Single P hase H eat Flux P aramet ers group , you c an set: •Heat Transf er C oefficien t: is in Equa tion 18.539 in the Fluent Theor y Guide .The following sp ecific- ations metho ds ar e available: –standar d: Uses a built-in tr eatmen t of the hea t transf er coefficien t for a liquid phase . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2202Modeling M ultiphase F lows–constan t –user-defined •Convective Augmen tation F actor: specifies the single-phase hea t flux augmen tation fac tor due t o the bubble agita tion. The following sp ecific ation metho ds ar e available: –chen : (default) U ses the c orrelations pr oposed b y Chen. See Semi-M echanistic B oiling M odel in the Fluent Theor y Guide for mor e inf ormation. –constan t –user-defined This input par amet er is a vailable only when Chen is selec ted in the Boiling M etho ds group box. •Heat Flux M ultiplier : is an additional fac tor to adjust a single-phase hea t flux ( in Equa tion 18.537 in the Fluent Theor y Guide ).This fac tor can b e used when the single phase-hea t flux is not pr edic ted well due t o an under-de velop ed turbulen t flo w, unc ertain ties in sur face roughness , interaction of ther mal and momen tum b oundar y layers when star ting fr om diff erent points or other fac tors.You can cho ose a constan t or user-defined specific ation metho d.The default v alue is 1. 10.In the Nuclea te Boiling H eat Flux P aramet ers group , you c an set: •Heat Transf er C oefficien t:The sp ecific ation metho ds ar e: –forst er-zub er: Uses the nuclea te boiling hea t transf er coefficien t proposed b y Forst er and Z uber (Equa tion 18.540 in the Fluent Theor y Guide ). –constan t –user-defined •Boiling S uppr ession F actor: Accoun ts for the nuclea te boiling suppr ession due t o the eff ect of f orced convection. The pr esenc e of bubbles due t o local boiling a t hea ted w alls augmen ts forced c onvection and suppr esses nuclea te boiling .The following sp ecific ation metho ds ar e available: –chen-st einer : (default) U ses the mo dific ation pr oposed b y Steiner ( Equa tion 18.546 in the Fluent Theor y Guide to Equa tion 18.548 in the Fluent Theor y Guide ). See Semi-M echanistic B oiling M odel in the Fluent Theor y Guide for mor e inf ormation. –chen : Uses C hen's c orrelation (Equa tion 18.548 in the Fluent Theor y Guide ). See Semi-M ech- anistic B oiling M odel in the Fluent Theor y Guide for mor e inf ormation. –constan t –user-defined This input par amet er is a vailable only when Chen is selec ted in the Boiling M etho ds group box. •Heat Flux M ultiplier : is an additional fac tor to adjust a nuclea te boiling hea t flux ( in Equa- tion 18.537 in the Fluent Theor y Guide ). Boiling c orrelations ar e obtained f or a sp ecific pr essur e and temp erature range f or certain ma terials.This additional hea t flux multiplier allo ws you t o tune in hea t 2203Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the M ixture Modeltransf er coefficien t when these c orrelations ar e used in gener alized sense .You c an cho ose a constan t or user-defined specific ation metho d.The default v alue is 1. You c an use the DEFINE_MASS_TR_PROPERTY UDF t o define input par amet ers f or the semi- mechansitic b oiling mo del. See DEFINE_MASS_TR_PROPERTY in the Fluent C ustomization Manual for details . 26.4.4.3. Cell Z one Sp ecific B oiling By default , boiling is enabled in all the c ell z ones .When b oiling is e xpected only in c ertain z ones , you can disable b oiling in other z ones t o mak e the c alcula tion fast er.This c an b e done b y clear ing Boiling Zone in the Fluid dialo g box (Multiphase tab). 26.4.4.4. Expert Options for the S emi-Mechanistic B oiling Mo del You c an acc ess e xpert options f or the semi-mechanistic b oiling mo del b y issuing the f ollowing t ext commands: solve/set/multiphase-numerics/heat-mass-transfer/boiling/show-expert- options? show expert options in semi-mechanistic boiling model? [yes] yes The e vaporation-c ondensa tion mo del dialo g box expands t o sho w b oiling mo del e xpert options . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2204Modeling M ultiphase F lowsFigur e 26.42: Boiling M odel E xpert Options You c an adjust the f ollowing par amet ers: Minimum S uperhea t is the minimum sup erheat requir ed f or the onset of nuclea te boiling .You c an define the Minimum S u- perhea t as: •constan t •hsu •user-defined The hsu metho d uses the e xpression pr oposed b y Hsu [51] (p.4007 ): wher e 2205Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the M ixture Model = minimum sup erheat = single phase hea t transf er coefficien t for liquid The r emaining nota tion is the same as in Semi-M echanistic B oiling M odel in the Fluent Theor y Guide . Maximum S uperhea t is the maximum sup erheat used in the nuclea te boiling hea t flux e xpressions . Wall Liquid Wetting F raction is the ar ea fr action of the w all w etted b y liquid . Since a w all ma y be complet ely w etted b y liquid e ven if the neighb oring c ell liquid v olume fr action is b elow 1, this is a cr ucial par amet er for the pr oper estim- ation of the hea t flux. You c an cho ose one of the f ollowing metho ds: transition-func tion (default) is the w etting fr action tha t controls the tr ansition fr om a c omplet ely w et to a c omplet ely dry wall sta te.When the liquid v olume fr action in the w all neighb oring c ells e xceeds a v alue of the Critical Liquid Volume F raction tha t you sp ecified , the w all is assumed t o be complet ely w etted by liquid .The w etting fr action is calcula ted as: wher e = v olume fr action of liquid = Critical Liquid Volume F raction (default = 0.2) = tr ansition c onstan t (default = 20) The dep endenc y of the w etting func tion on the liquid v olume fr action is sho wn in Fig- ure 26.43: Transition F unction v s.Volume F raction of Liquid (p.2207 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2206Modeling M ultiphase F lowsFigur e 26.43: Transition F unc tion v s.Volume F raction of Liquid wall-neighb or calcula tes the w etting fr action thr ough the neighb oring c ell v olume fr actions . constan t allows you t o sp ecify the w all liquid w etting fr action as a c onstan t value . user-defined allows you t o ho ok a user-defined func tion tha t specifies cust om v alues f or the w all liquid w etting fraction. 26.4.4.5. Solution Str ategies for the S emi-Mechanistic B oiling Mo del If you fac e difficulties in c onvergenc e for the ener gy equa tion while using the c onjuga te hea t transf er boundar y condition, you c an use the f ollowing str ategies: 1.Ideally , the semi-mechanistic b oiling mo del is b est suit ed f or cases with meshes with y+ > 30. In the worst c ase, y+ should not b e less than 12. 2.Use lo w or der schemes f or turbulenc e kinetic ener gy and momen tum. 3.Reduc e the r elaxa tion fac tor for turbulenc e kinetic ener gy to a v alue b etween 0.5-0.75. 4.Reduc e the r elaxa tion fac tor for hea t flux t o a v alue b etween 0.3-0.5. 5.In case of st eady sta te pseudo-tr ansien t simula tions tha t use aut oma tic time-sc ale, reduc e the fluid Time Scale F actor to 0.1. 6.For a lar ge change in hea t flux, you c an mo dify the hea t flux r elaxa tion fac tor using the f ollowing t ext command: solve/set/multiphase-numerics/heat-mass-transfer/boiling/heat-flux- relaxation-factor 2207Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the M ixture Modelheat flux relaxation factor for semi-mechanistic boiling model [0.8] 0.3 The hea t flux r elaxa tion fac tor will b e mo dified as f ollows: wher e and are the new and old hea t flux es, respectively, and is the hea t flux r elax- ation fac tor tha t you sp ecified . Note To carry out v alida tions against e xperimen tal da ta, you should first r un simula tions under non-b oiling c onditions . If the single-phase hea t flux diff ers fr om the a vailable da ta, you should adjust the single-phase hea t flux multiplier pr ior t o carrying out the b oiling simula- tions .There is no unique choic e of nuclea te boiling c orrelations; ther efore, the default nuclea te boiling c orrelation is not guar anteed t o work under all the op erating c onditions . ANSY S Fluen t provides fle xibilit y either t o tune in the e xisting metho ds or t o ho ok user- defined pr operties f or all supp orted b oiling mo del inputs . 26.5. Setting U p the E uler ian M odel For back ground inf ormation ab out the E uler ian mo del and the limita tions tha t apply , refer to Overview of the E uler ian M odel in the Theor y Guide . For additional inf ormation, see the f ollowing sec tions: 26.5.1. Additional G uidelines f or Euler ian M ultiphase S imula tions 26.5.2. Defining the P hases f or the E uler ian M odel 26.5.3. Modeling Turbulenc e 26.5.4. Including H eat Transf er Effects 26.5.5. Using an A lgebr aic In terfacial A rea M odel 26.5.6. Including the D ense D iscrete Phase M odel 26.5.7. Including the B oiling M odel 26.5.8. Including the M ulti-F luid VOF M odel 26.5.1. Additional G uidelines f or E uler ian M ultiphase S imula tions Onc e you ha ve det ermined tha t the E uler ian multiphase mo del is appr opriate for y our pr oblem (as descr ibed in Choosing a G ener al M ultiphase M odel in the Theor y Guide ), you should c onsider the computa tional eff ort requir ed t o solv e your multiphase pr oblem. The r equir ed c omputa tional eff ort dep ends str ongly on the numb er of tr ansp ort equa tions b eing solv ed and the degr ee of c oupling . For the E uler ian multiphase mo del, which has a lar ge numb er of highly c oupled tr ansp ort equa tions , computa tional e xpense will b e high. Before setting up y our pr oblem, try to reduc e the pr oblem statemen t to the simplest f orm p ossible . Instead of tr ying t o solv e your multiphase flo w in all of its c omple xity on y our first solution a ttempt , you c an star t with simple appr oxima tions and w ork your w ay up t o the final f orm of the pr oblem definition. Some suggestions f or simplifying a multiphase flo w pr oblem ar e list ed b elow: •Use a he xahedr al or quadr ilateral mesh (inst ead of a t etrahedr al or tr iangular mesh). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2208Modeling M ultiphase F lows•Reduc e the numb er of phases . You ma y find tha t even a v ery simple appr oxima tion will pr ovide y ou with useful inf ormation ab out your pr oblem. See Euler ian M odel (p.2274 ) and Setting S olution Limits (p.2599 ) for mor e solution str ategies f or E uler ian multiphase c alcula tions . 26.5.2. Defining the P hases f or the E uler ian M odel Instr uctions f or sp ecifying the nec essar y inf ormation f or the pr imar y and sec ondar y phases and their interaction f or an E uler ian multiphase c alcula tion ar e pr ovided b elow. 26.5.2.1. Defining the P rimar y Phase The pr ocedur e for defining the pr imar y phase in an E uler ian multiphase c alcula tion is the same as for a VOF c alcula tion. See Defining the P rimar y Phase (p.2171 ) for details . 26.5.2.2. Defining a N on-Gr anular S econdar y Phase To define a non-gr anular (tha t is, liquid or v apor) sec ondar y phase in an E uler ian multiphase c alcula tion, perform the f ollowing st eps: 1.Selec t the phase (f or e xample ,phase-2 ) in the Phases list. 2.Click Edit... to op en the Secondar y Phase D ialog Box (p.3444 ) (Figur e 26.44: The S econdar y Phase D ialog Box for a N on-G ranular P hase (p.2209 )). Figur e 26.44: The S econdar y Phase D ialo g Box for a N on-G ranular P hase 3.In the Secondar y Phase dialo g box, enter a Name for the phase . 2209Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the E uler ian M odel4.Specify which ma terial the phase c ontains b y cho osing the appr opriate ma terial in the Phase M aterial drop-do wn list. 5.Define the ma terial pr operties f or the Phase M aterial, following the same pr ocedur e you used t o set the ma terial pr operties f or the pr imar y phase (see Defining the P rimar y Phase (p.2171 )). 6.In the Properties group b ox, specify the Diamet er of the bubbles or dr oplets of this phase .You c an specify a c onstan t value , or use a user-defined func tion. See the Fluen t Customiza tion M anual for details about user-defined func tions . 7.Click OK in the Secondar y Phase dialo g box. 26.5.2.3. Defining a Gr anular S econdar y Phase To define a gr anular (tha t is, par ticula te) sec ondar y phase in an E uler ian multiphase c alcula tion, perform the f ollowing st eps: 1.Selec t the phase (f or e xample ,phase-2 ) in the Phases list. 2.Click Edit... to op en the Secondar y Phase D ialog Box (p.3444 ) (Figur e 26.45: The S econdar y Phase D ialog Box for a G ranular P hase (p.2211 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2210Modeling M ultiphase F lowsFigur e 26.45: The S econdar y Phase D ialo g Box for a G ranular P hase 3.In the Secondar y Phase dialo g box, enter a Name for the phase . 4.Specify which ma terial the phase c ontains b y cho osing the appr opriate ma terial in the Phase M aterial drop-do wn list. 5.Define the ma terial pr operties f or the Phase M aterial, following the same pr ocedur e you used t o set the ma terial pr operties f or the pr imar y phase (see Defining the P rimar y Phase (p.2171 )). For a gr anular phase (which must b e plac ed in the fluid ma terials c ategor y, as men tioned in Steps f or U sing a M ultiphase 2211Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the E uler ian M odelModel (p.2091 )), you need t o sp ecify only the densit y; you c an ignor e the v alues f or the other pr operties, sinc e the y will not b e used . Imp ortant Note tha t all pr operties f or gr anular flo ws can b e defined b y user-defined func tions (UDFs). See the Fluen t Customiza tion M anual for details ab out user-defined func tions . 6.Enable the Granular option. 7.(optional) Enable the Pack ed B ed option if y ou w ant to freeze the v elocity field f or the gr anular phase . Note tha t when y ou selec t the pack ed b ed option f or a phase , you should also use the fix ed v elocity option with a v alue of z ero for all v elocity comp onen ts for all in terior c ell z ones f or tha t phase . Using fixed v elocity in r adial dir ection as a c onstan t value (other than z ero) do es not ensur e continuit y.With the fix ed v elocity option, both v elocity and pr essur e are fix ed in a z one . Since fac e area in the r adial dir- ection is a func tion of r adial distanc e from the axis , it will r esult in a mass c onser vation pr oblem due t o flux imbalanc e. Using z ero fix ed v elocity in the r adial dir ection do es not c ause an y pr oblems r elated t o mass conser vation. 8.Specify the Granular Temp erature M odel. Choose either the default Phase P roperty option or the Partial D ifferential E qua tion option. See Granular Temp erature in the Theor y Guide for details . 9.In the Properties group b ox, specify the f ollowing pr operties of the par ticles of this phase: Diamet er specifies the diamet er of the par ticles .You c an selec t constan t in the dr op-do wn list and sp ecify a constan t value , or selec t user-defined to use a user-defined func tion. See the Fluen t Customiza tion Manual for details ab out user-defined func tions . Granular Visc osit y specifies the metho d for computing the k inetic ( ) and c ollisional ( ) comp onen ts of the granular visc osity (Equa tion 18.324 in the Fluent Theor y Guide ). Selec ting constan t,syamlal-obr ien (Equa tion 18.326 ), or gidasp ow (Equa tion 18.327 ) will use these e xpressions f or the k inetic p ortion of the visc osity and will c alcula te the c ollisional p ortion of the visc osity from Equa tion 18.325 in the Fluent Theor y Guide . Alternatively, you c an selec t user-defined to use a user-defined func tion. Note that if y ou selec t user-defined , your user-defined func tion must include b oth the k inetic p ortion and the c ollisional p ortion of the visc osity in the v alue it r etur ns. Granular Bulk Visc osit y specifies the solids bulk visc osity ( in Equa tion 18.177 in the Theor y Guide ).You c an selec t constan t (the default) in the dr op-do wn list and sp ecify a c onstan t value , selec t lun-et-al to comput e the v alue using Equa tion 18.328 in the Theor y Guide , or selec t user-defined to use a user-defined func tion. Frictional Visc osit y specifies a shear visc osity based on the visc ous-plastic flo w ( in Equa tion 18.324 in the Theor y Guide ). By default , the fr ictional visc osity is neglec ted, as indic ated b y the default selec tion of none in the dr op-do wn list. If you w ant to include the fr ictional visc osity, you c an selec t constan t and specify a c onstan t value , selec t schaeff er to comput e the v alue using Equa tion 18.329 in the Theor y Guide , or selec t user-defined to use a user-defined func tion. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2212Modeling M ultiphase F lowsAngle of In ternal F riction specifies a c onstan t value f or the angle used in Schaeff er’s expression f or fr ictional visc osity (Equa tion 18.329 in the Theor y Guide ).This par amet er is r elevant only if y ou ha ve selec ted schaeff er or user-defined for the Frictional Visc osit y. Frictional P ressur e specifies the pr essur e gr adien t term, , in the gr anular-phase momen tum equa tion. Choose none to exclude fr ictional pr essur e from y our c alcula tion, johnson-et-al to apply Equa tion 18.333 in the Theor y Guide ,syamlal-obr ien to apply Equa tion 18.245 in the Theor y Guide ,based-kt gf, wher e the fr ictional pr essur e is defined b y the k inetic theor y [29] (p.4006 ).The solids pr essur e tends to a lar ge v alue near the pack ing limit , dep ending on the mo del selec ted f or the r adial distr ibution func tion. You must ho ok a user-defined func tion when selec ting the user-defined option. See the Fluen t Customiza tion M anual for inf ormation on ho oking a UDF . Frictional M odulus is defined as (26.19) with , which is the der ived option. You c an also sp ecify a user-defined func tion f or the frictional mo dulus . Friction P ack ing Limit specifies a thr eshold v olume fr action a t which the fr ictional r egime b ecomes dominan t.The default value is 0.61. Granular C onduc tivit y specifies the solids gr anular c onduc tivit y ( in Equa tion 18.336 in the Theor y Guide ).You c an selec t syamlal-obr ien to comput e the v alue using Equa tion 18.337 in the Theor y Guide , selec t gidasp ow to comput e the v alue using Equa tion 18.338 in the Theor y Guide , or selec t user-defined to use a user-defined func tion. Note tha t in the algebr aic mo del, sho wn in Figur e 26.45: The S econdar y Phase Dialog Box for a G ranular P hase (p.2211 ), the gr anular c onduc tivit y is not r equir ed in the c omputa tion of the gr anular t emp erature.This has b een obtained b y neglec ting c onvection and diffusion in the transp ort equa tion, Equa tion 18.336 in the Theor y Guide [129] (p.4012 ). Granular Temp erature specifies t emp erature for the solids phase and is pr oportional t o the k inetic ener gy of the r andom motion of the par ticles . Choose the algebr aic,constan t,dpm-a veraged , or user-defined option. Note The dpm-a veraged metho d is only a vailable when using the D ense D iscrete Phase Model (DDPM). Solids P ressur e specifies the pr essur e gr adien t term, , in the gr anular-phase momen tum equa tion. Choose either the lun-et-al , the syamlal-obr ien, the ma-ahmadi ,none , or a user-defined option. Radial D istribution specifies a c orrection fac tor tha t mo difies the pr obabilit y of c ollisions b etween gr ains when the solid granular phase b ecomes dense . Choose either the lun-et-al , the syamlal-obr ien, the ma-ahmadi , the arastoopour, or a user-defined option. 2213Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the E uler ian M odelElasticit y M odulus is defined as (26.20) with . Pack ing Limit specifies the maximum v olume fr action f or the gr anular phase . For mono disp ersed spher es, the pack ing limit is ab out 0.63, which is the default v alue in ANSY S Fluen t. In p olydisp ersed c ases , however, smaller spher es c an fill the small gaps b etween lar ger spher es, so y ou ma y need t o incr ease the maximum pack ing limit. 10.Click OK in the Secondar y Phase dialo g box. 26.5.2.4. Defining the Int erfacial A rea C onc entr ation When using the E uler ian multiphase mo del, you c an cho ose t o solv e a tr ansp ort equa tion f or the in- terfacial ar ea, which allo ws for a distr ibution of sec ondar y phase diamet er, or y ou c an use an algeb- raic mo del t o comput e the in terfacial ar ea fr om a sp ecified diamet er.To use an algebr aic mo del, refer to Using an A lgebr aic In terfacial A rea M odel (p.2235 ).To solv e the tr ansp ort equa tion ( Interfacial A rea Concentration in the Fluent Theor y Guide ), perform the f ollowing st eps: 1.Selec t the phase (f or e xample ,phase-2 ) in the Phases list. 2.Click Edit... to op en the Secondar y Phase D ialog Box (p.3444 ) (Figur e 26.38: The S econdar y Phase D ialog Box Displa ying the In terfacial A rea C oncentration S ettings (p.2194 )). 3.In the Secondar y Phase dialo g box, enter a Name for the phase . 4.Specify which ma terial the phase c ontains b y cho osing the appr opriate ma terial in the Phase M aterial drop-do wn list. 5.Define the ma terial pr operties f or the Phase M aterial. 6.Enable the Interfacial A rea C onc entration option. Make sur e the Granular option is disabled f or the Interfacial A rea C onc entration option t o be visible in the in terface. 7.In the Properties group b ox, specify the f ollowing pr operties of the par ticles of this phase: Diamet er specifies the diamet er of the par ticles or bubbles .You c an selec t constan t in the dr op-do wn list and specify a c onstan t value , or selec t user-defined to use a user-defined func tion. See the Fluen t Cus- tomiza tion M anual for details ab out user-defined func tions .The Diamet er recommended setting is saut er-mean , allo wing f or the eff ects of the in terfacial ar ea c oncentration v alues t o be consider ed for mass , momen tum and hea t transf er acr oss the in terface between phases . Coalesc enc e Kernel and Br eak age K ernel allows you t o sp ecify the c oalesc ence and br eakage k ernels .You c an selec t none ,constan t,hibik i- ishii ,ishii-k im,yao-mor el, or user-defined .The thr ee options ,hibik i-ishii ,ishii-k im and yao-mor el are descr ibed in detail in Interfacial A rea C oncentration in the Theor y Guide . In addition t o sp ecifying the hibik i-ishii ,ishii-k im, and yao-mor el as the c oalesc ence and breakage k ernels , you c an also tune the pr operties of the thr ee mo dels b y using the Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2214Modeling M ultiphase F lows/define/phases/iac-expert/hibiki-ishii-model ,/define/phases/iac- expert/ishii-kim-model , and /define/phases/iac-expert/yao-morel-model text commands . For each of the thr ee mo dels y ou c an sp ecify the par amet ers list ed in Table 26.13: Paramet ers for the C oalesc ence and B reakage Ker nels (p.2215 ) Table 26.13: Paramet ers f or the C oalesc enc e and Br eak age K ernels Yao-M orel M odel Ishii-K im M odel Hibik i-Ishii M odel Coefficient K_c1 Coefficient Crc Coefficient Gamma_c Coefficient K_c3 Coefficient Cwe Coefficient K_c Coefficient K_b1 Coefficient C Coefficient Gamma_b alpha_max Coefficient Cti Coefficient K_b alpha_max alpha_max These v alues ar e discussed in gr eater detail in Interfacial A rea C oncentration in the Theor y Guide . Nuclea tion R ate is a sour ce term for the in terfacial ar ea c oncentration tha t mo dels the r ate of f ormation of the disp ersed phase .You c an cho ose fr om constan t or user-defined . If the Boiling M odel option is enabled , you can also selec t yao-mor el.The yao-mor el option is descr ibed in Yao-M orel M odel in the Theor y Guide . Critical Weber N umb er will need t o be sp ecified if y ou selec ted ishii-k im or yao-mor el for the Break age K ernel. Dissipa tion F unc tion gives y ou the option t o cho ose the f ormula which c alcula tes the dissipa tion r ate used in the hibik i- ishii and ishii-k im mo dels .You c an cho ose amongst constan t,wu-ishii-k im,fluen t-ke, and user- defined for the dissipa tion func tion. The wu-ishii-k im option uses a simple algebr aic c orrelation f or : (26.21) wher e and wher e , , , and are the mix ture densit y, mix ture velocity, mix ture molecular visc osity, and h ydraulic diamet er of the flo w pa th. When y ou selec t the wu-ishii-k im mo del, you will set an additional input f or Hydraulic D ia- met er. 2215Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the E uler ian M odelHydraulic D iamet er is the v alue used in Equa tion 26.21 (p.2215 ), should y ou use the wu-ishii-k im formula tion. Min/M ax D iamet er allow you t o sp ecify the minimum and maximum diamet ers of the sec ondar y phase t o which the interfacial ar ea c oncentration mo del is applied , preventing some c omputing anomalies t o spr ead beyond c ontrol. Note When solving a st eady-sta te pr oblem, the pr eferred setting f or the Under-Relaxa tion Factor is 1.0, as the in terfacial ar ea equa tion f or the b oiling mo dels is cur rently under-r e- laxed using a lo cally defined pseudo-time st ep. If you w ant extra explicit under-r elaxa tion, you ma y set the v alue of the Under-Relaxa tion F actor to less than one , this ma y be done only in c ase of ser ious c onvergenc e pr oblems with the in terfacial ar ea tr ansp ort equa tion. To impr ove convergenc e you c an swit ch t o a pseudo-time st ep f or the in terfacial ar ea concentration only , using the define/phases/iac-e xpert/iac-pseudo-time-st ep text com- mand and set the lo cal pseudo-time t o less than 1. 26.5.2.5. Defining the Int eraction B etween P hases For b oth gr anular and non-gr anular flo ws, you will need t o sp ecify the dr ag func tion t o be used in the c alcula tion of the momen tum e xchange c oefficien ts.You c an also sp ecify lif t forces, wall lubr ication forces (f or non-gr anular flo ws only), turbulen t disp ersion f orces, sur face tension eff ects, and vir tual mass f orce. For gr anular flo ws, you will also need t o sp ecify the r estitution c oefficien t(s) f or par ticle collisions . To sp ecify these par amet ers, click Interaction... to op en the Phase In teraction D ialog Box (p.3451 ) and visit the Drag,Lift,Wall L ubr ication ,Turbulen t Dispersion ,Collisions , and Surface Tension tabs . Setup → Models → Multiphase → Phases Edit... → Interaction... 26.5.2.5.1. Specifying the D rag F unc tion ANSY S Fluen t allo ws you t o sp ecify a dr ag func tion f or each pair of phases . Perform the f ollowing steps: 1.Click the Drag tab . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2216Modeling M ultiphase F lows2.For each pair of phases , selec t the appr opriate dr ag func tion fr om the c orresponding dr op-do wn list. •Selec t ishii to use the fluid-fluid dr ag func tion descr ibed b y Equa tion 18.434 in the Theor y Guide . This option is a vailable when the b oiling mo del is enabled . •Selec t schiller-naumann to use the fluid-fluid dr ag func tion descr ibed b y Equa tion 18.192 in the Theor y Guide .The Schiller and N aumann mo del is the default metho d, and it is acc eptable f or gener al use in all fluid-fluid multiphase c alcula tions .When using the homo geneous p opula tion balanc e models y ou c an also selec t schiller-naumann-pb in which c ase the in terfacial ar ea will b e calcula ted directly fr om the p opula tion balanc e variables . •Selec t morsi-ale xander to use the fluid-fluid dr ag func tion descr ibed b y Equa tion 18.196 in the Theor y Guide .The M orsi and A lexander mo del is the most c omplet e, adjusting the func tion definition frequen tly o ver a lar ge r ange of R eynolds numb ers, but c alcula tions with this mo del ma y be less stable than with the other mo dels . •Selec t symmetr ic to use the fluid-fluid dr ag func tion descr ibed b y Equa tion 18.202 in the Theor y Guide .The symmetr ic mo del is r ecommended f or flo ws in which the sec ondar y (disp ersed) phase in one r egion of the domain b ecomes the pr imar y (continuous) phase in another . For e xample , if air is injec ted in to the b ottom of a c ontainer filled halfw ay with w ater, the air is the disp ersed phase in the bottom half of the c ontainer ; in the t op half of the c ontainer , the air is the c ontinuous phase .The symmetr ic drag la w is the default metho d for the Multi-F luid VOF M odel, which is a vailable with Euler ian multiphase mo del. •Selec t grace to use the fluid-fluid dr ag func tion descr ibed b y Equa tion 18.207 in the Theor y Guide .The G race mo del is r ecommended f or gas-liquid flo ws in which the bubbles c an ha ve a range of shap es such as spher ical, elliptic al, or c ap. In the Grace Swarm C orrection dialo g box tha t op ens aut oma tically when y ou first selec t this model, you c an sp ecify Coefficien t: Cexp ( in Equa tion 18.207 in the Fluent Theor y Guide ) as constan t or user-defined . Depending on the flo w regime and the bubble siz e, the f ollowing values should b e used: –Sparsely distr ibut ed fluid par ticles In flo ws with sparsely distr ibut ed fluid par ticles , in Equa tion 18.207 in the Fluent Theor y Guide is z ero (default). –Densely distr ibut ed fluid par ticles →Since small bubbles t end t o rise slo wly in high gas v olume fr actions due t o an incr ease in the effective mix ture visc osity, a nega tive should b e used .The Ishii-Z uber correlation uses an exponen t of -1 f or this limit. A value of -0.5 has also b een used succ essfully b y some in vestiga tors. →Large bubbles , on the other hand , tend t o rise fast er at high gas v olume fr actions b ecause the y are dr agged along b y the w akes of other bubbles .This is mo deled b y using a p ositiv e .The Ishii-Z uber correlation uses an e xponen t of 2 f or this r egime . A value of 4 has also b een used succ essfully b y some r esear chers in the past See Grace et al. Model in the Fluent Theor y Guide for mor e inf ormation. •Selec t tomiy ama to use the fluid-fluid dr ag func tion descr ibed b y Equa tion 18.213 in the Theor y Guide . Like the G race mo del, the Tomiy ama mo del is r ecommended f or gas-liquid flo ws in which the bubbles c an ha ve a r ange of shap es such as spher ical, elliptic al, or c ap. 2217Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the E uler ian M odel•Selec t ishii-zub er to use the fluid-fluid dr ag func tion descr ibed in Ishii-Z uber D rag M odel in the Fluent Theor y Guide .The mo del aut oma tically acc oun ts for sw arms of bubbles mo ving t ogether in high gas volume fr actions . Like the G race and Tomiy ama dr ag mo dels , the I shii-Z uber dr ag la w is r ecommended for gas-liquid flo ws in which bubbles ma y ha ve a r ange of shap es such as spher ical, elliptic al, or c ap. •Selec t anisotr opic to use the fluid-fluid dr ag func tion descr ibed in Multi-F luid VOF M odel in the Theor y Guide .The anisotr opic drag la w is r ecommended f or fr ee sur face mo deling . It is based on higher dr ag in the nor mal dir ection t o the in terface and lo wer dr ag in the tangen tial dir ection t o the interface. •Selec t univ ersal-dr ag for bubble-liquid and/or dr oplet-gas flo w when the char acteristic length of the flo w domain is much gr eater than the a veraged siz e of the dr oplets/bubbles . It is suitable for flo ws in which the bubbles/dr oplets ma y ha ve a r ange of shap es.The univ ersal dr ag la w is descr ibed using Equa tion 18.224 in the Theor y Guide .When univ ersal-dr ag is selec ted, you will need t o set a v alue f or the sur face tension c oefficien t, under the Surface Tension tab , in the Phase In teraction dialo g box.This v alue will apply t o the pr imar y phase and the sec ondar y phase . •Selec t wen-yu to use the fluid-solid dr ag func tion descr ibed b y Equa tion 18.259 in the Theor y Guide . The Wen and Yu mo del is applic able f or dilut e phase flo ws, in which the t otal sec ondar y phase v olume fraction is signific antly lo wer than tha t of the pr imar y phase .When using the homo geneous p opula tion balanc e mo dels y ou c an also selec t wen-yu-pb in which c ase the in terfacial ar ea will b e calcula ted directly fr om the p opula tion balanc e variables . •Selec t gidasp ow to use the fluid-solid dr ag func tion descr ibed b y Equa tion 18.261 in the Theor y Guide .The G idasp ow mo del is r ecommended f or dense fluidiz ed b eds. •Selec t syamlal-obr ien to use the fluid-solid dr ag func tion descr ibed b y Equa tion 18.246 in the Theor y Guide .The S yamlal-O ’Brien mo del is r ecommended f or use in c onjunc tion with the S yamlal-O ’Brien model f or gr anular visc osity. •Selec t syamlal-obr ien-par a to use the par amet erized f ormula tion of the S yamlal-O ’Brien mo del de- scribed b y Equa tion 18.256 in the Theor y Guide .This mo del addr esses under/o ver-pr edic tion of b ed expansion tha t can ar ise with syamlal-obr ien.When y ou first selec t this mo del, you will b e pr esen ted with the Syamlal O brien M odel dialo g box. Figur e 26.46: Syamlal O brien M odel Dialo g Box There ar e two inputs: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2218Modeling M ultiphase F lowsVoid F raction the v olume fr action of the gas phase in the b ed a t the minimum fluidiza tion c ondition Minimum F luidiza tion Velocity the e xpected or e xperimen tally-det ermined nominal minimum fluidiza tion v elocity of the gas phase Onc e you ha ve input these v alues , click Valida te/A pply to comput e the c oefficien ts c1 and d1 used in Equa tion 18.257 in the Fluent Theor y Guide . A message will also b e pr inted t o the text user in terface summar izing the fluid and flo w pr operties used in the c omputa tion and the resulting v alues .You should check tha t these pr operty values ar e consist ent with the pr operties set elsewher e. Imp ortant If you change pr operty values in the Create/Edit M aterials dialo g box or dia- met er in the Secondar y Phase dialo g box, you must initializ e the flo w field or run a t least one it eration b efore computing c1 and d1. Other wise , incorrect properties will b e used in the c omputa tion. Note tha t the syamlal-obr ien-par a mo del is appr opriate only f or G eldar t Group B par ticles and is only applic able t o cases in volving a single sec ondar y phase . •Selec t syamlal-obr ien-symmetr ic to use the solid-solid dr ag func tion descr ibed b y Equa tion 18.267 in the Theor y Guide .The symmetr ic Syamlal-O ’Brien mo del is appr opriate for a pair of solid phases . •Selec t huilin-gidasp ow to use the fluid-solid dr ag func tion descr ibed b y Equa tion 18.263 in the Theor y Guide .This option pr ovides a b etter blending func tion f or the G idasp ow mo del when mo ving from the dense pack ing limit t o the dilut e flo w limit. •Selec t gibilar o to use the fluid-solid dr ag func tion descr ibed b y Equa tion 18.265 in the Theor y Guide . This option is used f or cir cula ting fluidiz ed b eds •Selec t constan t to sp ecify a c onstan t value f or the dr ag func tion, and then sp ecify the v alue in the text field . •Selec t user-defined to use a user-defined func tion f or the dr ag func tion (see the Fluen t Customiza tion Manual for details). •If you w ant to temp orarily ignor e the in teraction b etween t wo phases , selec t none . 26.5.2.5.1.1. Drag Mo dific ation When using the E uler ian or M ixture multiphase mo dels , you c an optionally sp ecify a dr ag mo dific ation term for the selec ted dr ag la w.The dr ag mo dific ation t erm ac ts as a multiplier f or the dr ag c oefficien t comput ed fr om the mo dels detailed in Specifying the D rag F unction (p.2216 ).You c an sp ecify the drag mo dific ation t erm individually f or each pair of pr imar y-sec ondar y phases .To enable dr ag modific ation, perform the f ollowing st eps: 1.Check Drag M odific ation in the Drag tab of the Phase In teraction dialo g box. An additional dr op-do wn list will app ear under Drag F actor for each pr imar y-sec ondar y phase pair . 2219Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the E uler ian M odel2.For each pair of phases , selec t the Drag F actor to use fr om the dr op-do wn list. •Selec t none to use the selec ted dr ag mo del without mo dific ation. •Selec t constan t to sp ecify a c onstan t value f or the dr ag mo dific ation fac tor. •Selec t brucato to use the B rucato et al. correlation descr ibed b y Brucato et al. Correlation in the Theor y Guide . •Selec t user-defined to use a user-defined func tion f or the dr ag mo dific ation fac tor (see DEFINE_EXCHANGE_PROPERTY in the Fluen t Customiza tion M anual for details). For additional details on the implemen tation of the dr ag mo dific ation, see Drag M odific ation in the Theor y Guide . 26.5.2.5.2. Specifying the R estitution C oefficients (Gr anular F low O nly) For gr anular flo ws, you need t o sp ecify the c oefficien ts of r estitution f or c ollisions b etween par ticles ( in Equa tion 18.267 and in Equa tion 18.307 in the Theor y Guide ). In addition t o sp ecifying the restitution c oefficien t for c ollisions b etween each pair of gr anular phases , you will also sp ecify the restitution c oefficien t for c ollisions b etween par ticles of the same phase . Perform the f ollowing st eps: 1.Click the Collisions tab t o displa y the Restitution C oefficien t inputs . 2.For each pair of phases , specify a c onstan t restitution c oefficien t. All restitution c oefficien ts ar e equal to 0.9 b y default. 26.5.2.5.3. Including the Lif t Force For b oth gr anular and non-gr anular flo ws, it is p ossible t o include the eff ect of lif t forces ( in Equa tion 18.272 in the Theor y Guide ) on the sec ondar y phase par ticles , droplets , or bubbles .These lift forces ac t on a par ticle , droplet , or bubble mainly due t o velocity gr adien ts in the pr imar y-phase flow field . In most c ases , the lif t force is insignific ant compar ed t o the dr ag f orce, so ther e is no reason t o include it. If the lif t force is signific ant (for e xample , if the phases separ ate quick ly), you may want to include this eff ect. Imp ortant Note tha t the lif t force will b e mor e signific ant for lar ger par ticles , but the ANSY S Flu- ent mo del assumes tha t the par ticle diamet er is much smaller than the in terparticle spacing . Therefore, the inclusion of lif t forces is not appr opriate for closely pack ed par ticles or f or very small par ticles . To include the eff ect of lif t forces, perform the f ollowing st eps: 1.Click the Lift tab t o displa y the Lift Coefficien t inputs . 2.For each pair of phases , selec t the appr opriate sp ecific ation metho d from the c orresponding dr op-do wn list. Note tha t, sinc e the lif t forces for a par ticle , droplet , or bubble ar e due mainly t o velocity gr adien ts in the pr imar y-phase flo w field , you will not sp ecify lif t coefficien ts for pairs c onsisting of t wo sec ondar y Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2220Modeling M ultiphase F lowsphases; lift coefficien ts ar e sp ecified only f or pairs c onsisting of a sec ondar y phase and the pr imar y phase . •Selec t none (the default) t o ignor e the eff ect of lif t forces. •Selec t constan t to sp ecify a c onstan t lift coefficien t, and then sp ecify the v alue in the t ext field . •Selec t mor aga to use the M oraga lif t mo del ( Moraga Lif t Force Model in the Theor y Guide ).The Moraga lif t mo del is applic able t o spher ical solid par ticles , drops, and bubbles . •Selec t saffman-mei to use the S affman-M ei lif t mo del ( Saffman-M ei Lif t Force Model in the Theor y Guide ).The S affman-M ei lif t mo del is applic able t o spher ical solid par ticles , and t o dr ops and bubbles that are not signific antly dist orted. •Selec t legendr e-magnaudet to use the L egendr e—M agnaudet lif t mo del ( Legendr e-M agnaudet Lif t Force Model in the Theor y Guide ).The L egendr e-M agnaudet mo del is applic able t o small diamet er spher ical fluid par ticles , though it c an b e applied t o non-dist orted liquid dr ops and bubbles . It acc oun ts for momen tum tr ansf er b etween the flo w ar ound the par ticle and the inner r ecircula tion flo w inside the fluid par ticle c aused b y fluid fr iction/str esses a t the fluid in terface. •Selec t tomiy ama to use the Tomiy ama lif t mo del ( Tomiy ama Lif t Force Model in the Theor y Guide ). The Tomiy ama mo del is applic able t o lar ger-sc ale def ormable bubbles in the ellipsoidal and spher ical cap r egimes . Its main f eature is the pr edic tion of the cr oss-o ver p oint in bubble siz e at which par ticle distortion c auses a r eversal in the sign of the lif t force. •Selec t user-defined to use a user-defined func tion f or the lif t coefficien t (see the Fluen t Customiza tion Manual for details). 26.5.2.5.4. Including the Wall L ubric ation F orce For liquid-gas bubbly flo ws using the E uler ian multiphase mo del, you c an include the eff ect of w all lubr ication f orces ( in Equa tion 18.176 in the Theor y Guide ) on the sec ondar y phase bubbles . These f orces tend t o push the bubbles a way from w alls a t small w all distanc es. For details on ho w wall lubr ication is mo deled in ANSY S Fluen t see Wall L ubrication F orce in the Theor y Guide . To include the eff ect of w all lubr ication f orces, perform the f ollowing st eps: 1.Click the Wall L ubr ication tab t o displa y the Wall L ubr ication inputs . 2.For each pair of phases , selec t the appr opriate sp ecific ation metho d from the c orresponding dr op-do wn list. Note tha t you will sp ecify the w all lubr ication only f or pairs c onsisting of a sec ondar y phase and the pr imar y phase . •Selec t none (the default) t o ignor e the eff ect of w all lubr ication f orces. •Selec t antal-et-al to use the A ntal et al. mo del ( Antal et al. Model in the Theor y Guide ).You c an edit the mo del par amet ers in the Antal M odel dialo g box (Figur e 26.47: Antal et al. Model D ialog Box (p.2222 )). 2221Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the E uler ian M odelFigur e 26.47: Antal et al. Model D ialo g Box The f ollowing mo del par amet ers ar e available: Coefficien t: Cw1 Specify the c onstan t in Equa tion 18.286 in the Theor y Guide .You c an en ter a c onstan t value or sp ecify a user-defined func tion defined using the DEFINE_EXCHANGE_PROPERTY macr o (DEFINE_EXCHANGE_PROPERTY ). Coefficien t: Cw2 Specify the c onstan t in Equa tion 18.286 in the Theor y Guide .You c an en ter a c onstan t value or sp ecify a user-defined func tion defined using the DEFINE_EXCHANGE_PROPERTY macr o (DEFINE_EXCHANGE_PROPERTY ). •Selec t tomiy ama to use the Tomiy ama mo del ( Tomiy ama M odel in the Theor y Guide ).This mo del is only applic able f or pip e geometr ies.You c an en ter the H ydraulic D iamet er for y our geometr y in the Tomiy ama M odel dialo g box (Figur e 26.48: Tomiy ama M odel D ialog Box (p.2222 )). Figur e 26.48: Tomiy ama M odel D ialo g Box The following mo del par amet ers ar e available: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2222Modeling M ultiphase F lowsHydraulic D iamet er: D (m) Specify the h ydraulic diamet er, , in Equa tion 18.288 in the Theor y Guide . Imp ortant The h ydraulic diamet er must b e en tered in units of met ers. •Selec t frank to use the F rank et al. mo del ( Frank M odel in the Theor y Guide ).You c an edit the mo del paramet ers in the Frank M odel dialo g box (Figur e 26.49: Frank M odel D ialog Box (p.2223 )). Figur e 26.49: Frank M odel D ialo g Box The f ollowing mo del par amet ers ar e available: Coefficien t: Cw c Specify the cut off c oefficien t, , in Equa tion 18.290 in the Theor y Guide .You c an en ter a c onstan t value or sp ecify a user-defined func tion defined using the DEFINE_EXCHANGE_PROPERTY macr o (DEFINE_EXCHANGE_PROPERTY ). Coefficien t: Cw d Specify the damping c oefficien t, , in Equa tion 18.290 in the Theor y Guide .You c an en ter a constan t value or sp ecify a user-defined func tion defined using the DEFINE_EXCHANGE_PROP- ERTY macr o (DEFINE_EXCHANGE_PROPERTY ). Power-la w Inde x: m Specify the p ower la w constan t, , in Equa tion 18.290 in the Theor y Guide .You c an en ter a constan t value or sp ecify a user-defined func tion defined using the DEFINE_EXCHANGE_PROP- ERTY macr o (DEFINE_EXCHANGE_PROPERTY ). •Selec t hosak awa to use the H osok awa mo del ( Hosok awa Model in the Theor y Guide ).You c an edit the mo del par amet ers in the Hosok awa M odel dialo g box (Figur e 26.50: Hosok awa Model D ialog Box (p.2224 )). 2223Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the E uler ian M odelFigur e 26.50: Hosok awa M odel D ialo g Box The f ollowing mo del par amet ers ar e available: Formula tions Selec t which f ormula tion of the H osok awa mo del t o use .You c an selec t either Frank or Tomiy ama . Hosok awa Coefficien t Specify the c oefficien t of the E otvos numb er in Equa tion 18.291 in the Theor y Guide .You c an enter a c onstan t value or sp ecify a user-defined func tion defined using the DEFINE_EX- CHANGE_PROPERTY macr o (DEFINE_EXCHANGE_PROPERTY ). Coefficien ts Specify the mo del par amet ers asso ciated with the f ormula tion y ou selec ted under Formula tions . •Selec t user-defined to use a user-defined func tion f or the w all lubr ication c oefficien t (see DEFINE_EXCHANGE_PROPERTY in the Fluent C ustomization Manual for details). 26.5.2.5.5. Including the Turbulent D ispersion F orce For turbulen t flo ws using the E uler ian multiphase mo del, you c an include the eff ects of turbulen t disp ersion f orce ( in Equa tion 18.176 in the Theor y Guide ).The turbulen t disp ersion f orce ac ts as a turbulen t diffusion in disp ersed flo ws. For details on ho w turbulen t disp ersion is mo deled in ANSY S Fluen t see Turbulen t Dispersion F orce in the Theor y Guide . To include the eff ects of turbulen t disp ersion f orce, perform the f ollowing st eps: 1.Click the Turbulen t Dispersion tab t o displa y the Turbulen t Dispersion inputs . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2224Modeling M ultiphase F lows2.For each pair of phases , selec t the appr opriate sp ecific ation metho d from the c orresponding dr op-do wn list. Note tha t you will sp ecify the turbulen t disp ersion only f or pairs c onsisting of a sec ondar y phase and the pr imar y phase . •Selec t none (the default) t o ignor e the eff ects of turbulen t disp ersion. •Selec t lopez-de-b ertodano to use the L opez de B ertodano mo del ( Lopez de B ertodano M odel in the Theor y Guide ).You c an edit the mo del par amet ers in the Lopez de B ertodano M odel dialo g box (Figur e 26.51: Lopez de B ertodano M odel D ialog Box (p.2225 )). Figur e 26.51: Lopez de B ertodano M odel D ialo g Box The f ollowing mo del par amet ers ar e available: Model C onstan t Specify the c oefficien t, , in Equa tion 18.295 in the Theor y Guide .You c an en ter a c onstan t value or sp ecify a user-defined func tion defined using the DEFINE_EXCHANGE_PROPERTY macr o (DEFINE_EXCHANGE_PROPERTY ). Limiting F unc tion Specify the limiting func tion t o use .You ma y selec t none , the standar d limiting func tion, or a user-defined func tion using the DEFINE_EXCHANGE_PROPERTY macr o (DEFINE_EX- CHANGE_PROPERTY ). See Limiting F unctions f or the Turbulen t Dispersion F orce in Fluen t Theor y Guide for details on the limiting func tions . •Selec t simonin to use the S imonin mo del ( Simonin M odel in the Theor y Guide ). You c an sp ecify the mo del par amet ers in the Simonin M odel dialo g box (Figur e 26.52: Simonin Model D ialog Box (p.2226 )). 2225Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the E uler ian M odelFigur e 26.52: Simonin M odel D ialo g Box The f ollowing mo del par amet ers ar e available: Model C onstan t Specify the c oefficien t, , in Equa tion 18.297 in the Theor y Guide .You c an en ter a c onstan t value or sp ecify a user-defined func tion defined using the DEFINE_EXCHANGE_PROPERTY macr o (DEFINE_EXCHANGE_PROPERTY ). Limiting F unc tion Specify the limiting func tion t o use .You ma y selec t none , the standar d limiting func tion, or a user-defined func tion using the DEFINE_EX CHANGE_PR OPER TY macr o (DEFINE_EX- CHANGE_PROPERTY ). See Limiting F unctions f or the Turbulen t Dispersion F orce in Fluen t Theor y Guide for details on the limiting func tions . •Selec t bur ns-et-al to use the B urns et al. mo del ( Burns et al. Model in the Theor y Guide ).You c an edit the mo del par amet ers in the Bur ns-et-al M odel dialo g box (Figur e 26.53: Burns et al. Model Dialog Box (p.2226 )). Figur e 26.53: Bur ns et al. Model D ialo g Box The f ollowing mo del par amet ers ar e available: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2226Modeling M ultiphase F lowsModel C onstan t Specify the c oefficien t, , in Equa tion 18.299 in the Theor y Guide .You c an en ter a c onstan t value or sp ecify a user-defined func tion defined using the DEFINE_EXCHANGE_PROPERTY macr o (DEFINE_EXCHANGE_PROPERTY ). Limiting F unc tion Specify the limiting func tion t o use .You ma y selec t none , the standar d limiting func tion, or a user-defined func tion using the DEFINE_EXCHANGE_PROPERTY macr o (DEFINE_EX- CHANGE_PROPERTY ). See Limiting F unctions f or the Turbulen t Dispersion F orce in Fluen t Theor y Guide for details on the limiting func tions . •Selec t diffusion-in-v of to use the D iffusion in VOF mo del ( Diffusion in VOF M odel in the Theor y Guide ).You c an edit the mo del par amet ers in the Diffusion-in-v of M odel dialo g box (Figur e 26.54: Dif- fusion—in—v of M odel D ialog Box (p.2227 )). Figur e 26.54: Diffusion—in—v of M odel D ialo g Box The f ollowing mo del par amet ers ar e available: VOF D iffusion C oefficien t Specify the c oefficien t, , in Equa tion 18.302 in the Theor y Guide . Limiting F unc tion Specify the limiting func tion t o use .You ma y selec t none , the standar d limiting func tion, or a user-defined func tion using the DEFINE_EXCHANGE_PROPERTY macr o (DEFINE_EX- CHANGE_PROPERTY ). See Limiting F unctions f or the Turbulen t Dispersion F orce in Fluen t Theor y Guide for details on the limiting func tions . •Selec t user-defined to use a user-defined func tion f or the turbulen t disp ersion (see DEFINE_VEC- TOR_EXCHANGE_PROPERTY in the Fluent C ustomization Manual for details). 26.5.2.5.6. Including S urface Tension and Wall A dhesion E ffec ts As discussed in When Sur face Tension E ffects A re Imp ortant in the Theor y Guide , the imp ortanc e of surface tension eff ects dep ends on the v alue of the c apillar y numb er, Ca (defined b y Equa tion 18.32 2227Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the E uler ian M odelin the Theor y Guide ), or the Weber numb er,We (defined b y Equa tion 18.33 in the Theor y Guide ). Surface tension eff ects can b e neglec ted if C a or We . Imp ortant Note tha t the c alcula tion of sur face tension eff ects will b e mor e accur ate if y ou use a quadr ilateral or he xahedr al mesh in the ar ea(s) of the c omputa tional domain wher e sur face tension is signific ant. If you c annot use a quadr ilateral or he xahedr al mesh f or the en tire domain, then y ou should use a h ybrid mesh, with quadr ilaterals or he xahedr a in the af- fected ar eas. ANSY S Fluen t also off ers an option t o use VOF gr adien ts at the no des f or curvature calcula tions on meshes when mor e accur acy is desir ed. For mor e inf ormation, see Surface Tension and A dhesion in the Theor y Guide . If you w ant to include the eff ects of sur face tension along the in terface between one or mor e pairs of phases , as descr ibed in Surface Tension and A dhesion in the Theor y Guide , refer to Including Surface Tension and A dhesion E ffects (p.2173 ). 26.5.2.5.7. Including the Virtual M ass F orce For b oth gr anular and non-gr anular flo ws, it is p ossible t o include the “virtual mass f orce” ( in Equa tion 18.305 in the Theor y Guide ) tha t is pr esen t when a sec ondar y phase acc elerates relative to the pr imar y phase .The vir tual mass eff ect is signific ant when the sec ondar y phase densit y is much smaller than the pr imar y phase densit y (for e xample , for a tr ansien t bubble c olumn). To include the eff ect of the vir tual mass f orce perform the f ollowing st eps: 1. Click the Virtual M ass tab t o displa y the Virtual M ass inputs . 2. Enable Virtual M ass M odeling . 3. For each phase pair list ed under Virtual M ass C oefficien t, selec t the metho d for sp ecifying the vir tual mass c oefficien t, , in Equa tion 18.305 in the Fluent Theor y Guide .You c an cho ose fr om the f ollowing metho ds: none Disable vir tual mass mo deling f or the phase pair . constan t Specify a c onstan t value f or the c oefficien t.The default v alue of 0.5 is typic al. user-defined Use a user-defined func tion cr eated with the DEFINE_EXCHANGE_PROPERTY macr o. See DEFINE_EXCHANGE_PROPERTY in the Fluent C ustomization Manual for details . Imp ortant No vir tual mass eff ects will b e included unless the Virtual M ass M odeling option is enabled . 4. If desir ed, you c an enable the Implicit metho d for vir tual mass . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2228Modeling M ultiphase F lowsWhen using the Implicit metho d, the Default option uses the c omplet e term in Equa tion 18.305 . You c an also cho ose Option 2 or Option 3 , which use lo cally tr uncated f orms of the vir tual mass t erms in c ells wher e div ergenc e is det ected. The Implicit metho d is r ecommended f or st eady-sta te coupled simula tions as it off ers impr oved convergenc e in such c ases .The r ecommended appr oach is t o begin the simula tion using Option 2. Onc e the solution has c onverged enough t o establish the basic flo w field , swit ch back t o Default to include the c omplet e vir tual mass t erm. 26.5.3. Modeling Turbulenc e If you ar e using the E uler ian mo del t o solv e a turbulen t flo w, you will need t o cho ose one of turbulenc e models descr ibed in Turbulenc e M odels in the Theor y Guide in the Viscous M odel D ialog Box (p.3253 ) (Figur e 26.55: The Viscous M odel D ialog Box for an E uler ian M ultiphase C alcula tion (p.2230 )). 2229Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the E uler ian M odelFigur e 26.55: The Visc ous M odel D ialo g Box for an E uler ian M ultiphase C alcula tion The pr ocedur e is as f ollows: 1.Selec t k-epsilon ,k-omega , or Reynolds S tress under Model. 2.Selec t the desir ed k-epsilon M odel,k-omega M odel, or Reynolds-S tress M odel and an y other r elated paramet ers, as descr ibed f or single-phase c alcula tions in Steps in U sing a Turbulenc e Model (p.1392 ). 3.Under Turbulenc e M ultiphase M odel or RSM M ultiphase M odel, indic ate the desir ed multiphase tur- bulenc e mo del (see Turbulenc e Models in the Theor y Guide for details ab out each): •Selec t Mixture to use the mix ture turbulenc e mo del. This is the default mo del. •Selec t Dispersed to use the disp ersed turbulenc e mo del. This mo del is applic able when ther e is clear ly one pr imar y continuous phase and the r est ar e disp ersed dilut e sec ondar y phases . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2230Modeling M ultiphase F lows•Selec t Per P hase to use a - or - turbulenc e mo del f or each phase .This mo del is appr opriate when the turbulenc e transf er among the phases pla ys a dominan t role. 26.5.3.1. Including Turbulenc e Int eraction S our ce Terms By default , interphase turbulenc e sour ce terms ar e not included in the c alcula tion. If you w ant to in- clude these sour ce terms, you c an enable them fr om the Turbulenc e In teraction tab of the Phase Interaction D ialog Box (p.3451 ). Setup → Models → Multiphase → Phases Edit... → Interaction... 1.Click the Interaction... butt on t o op en the Phase In teraction dialo g box (for e xample ,Figur e 26.56: The Phase In teraction D ialog Box for Turbulenc e Interaction (p.2231 )). Figur e 26.56: The P hase In teraction D ialo g Box for Turbulenc e In teraction 2.Click the Turbulenc e In teraction tab in the Phase In teraction dialo g box. 3.For each pair of phases , selec t the desir ed c orrelation f or the Turbulenc e Interaction. The a vailable options are: •selec t none to omit turbulenc e interaction sour ce terms.This is the default. •selec t troshk o-hassan to use the Troshk o-Hassan mo del descr ibed in Troshk o-Hassan in the Fluent Theor y Guide .You c an edit the mo del par amet ers in the Troshk o-H assan M odel dialo g box (Fig- ure 26.57: Troshk o-Hassan M odel D ialog Box (p.2232 )). 2231Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the E uler ian M odelFigur e 26.57: Troshk o-H assan M odel D ialo g Box The f ollowing mo del par amet ers ar e available: Coefficien t: Cke Specify the c oefficien t, , in the equa tions in Troshk o-Hassan in the Fluent Theor y Guide . Coefficien t: Ctd Specify the c oefficien t, , in the equa tions in Troshk o-Hassan in the Fluent Theor y Guide . •selec t sato to use the S ato mo del descr ibed in Sato in the Fluent Theor y Guide .You c an edit the mo del paramet ers in the Sato M odel dialo g box (Figur e 26.58: Sato M odel D ialog Box (p.2232 )). Figur e 26.58: Sato M odel D ialo g Box The f ollowing mo del par amet ers ar e available: Model C oefficien t Specify the c oefficien t, , in the equa tions in Sato in the Fluent Theor y Guide . •selec t simonin-et-al to use the S imonin et al. mo del descr ibed in Simonin et al. in the Fluent Theor y Guide .This option is a vailable only when Dispersed or Per P hase is selec ted in the Visc ous M odel dialo g box.You c an edit the mo del par amet ers in the Simonin-et-al M odel dialo g box (Figur e 26.59: Si- monin-et-al M odel D ialog Box (p.2233 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2232Modeling M ultiphase F lowsFigur e 26.59: Simonin-et-al M odel D ialo g Box The f ollowing mo del par amet ers ar e available: Drift Turbulen t Sour ce include the p ortion the turbulen t kinetic ener gy sour ce term ar ising fr om the dr ift velocity. Model C oefficien t Specify the c oefficien t, , in the equa tions in Simonin et al. in the Fluent Theor y Guide . If you decide t o enable turbulenc e in teraction f or multiple phase pairs , it is r ecommended tha t you avoid mixing the diff erent mo dels and tha t you selec t the same mo del f or each phase pair with tur- bulenc e in teraction enabled . Note tha t the inclusion of these t erms c an slo w do wn c onvergenc e notic eably . If you ar e lo oking f or additional accur acy, you ma y want to comput e a solution first without these sour ces, and then c on- tinue the c alcula tion with these t erms included . In most c ases these t erms c an b e neglec ted. 26.5.3.2. Customizing the k- ε Multiphase Turbulent Visc osit y If you ar e using the - multiphase turbulenc e mo del, a user-defined func tion c an b e used t o cus- tomiz e the turbulen t visc osity for each phase .This option will enable y ou t o mo dify in the - model. For mor e inf ormation, see the Fluen t Customiza tion M anual . In the Visc ous M odel dialo g box, under User-D efined F unc tions , selec t the appr opriate user-defined func tion in the Turbulen t Visc osit y drop-do wn list. 26.5.4. Including H eat Transf er E ffects To define hea t transf er in a multiphase E uler ian simula tion, you will need t o visit the Phase In teraction dialo g box, after y ou ha ve enabled the ener gy equa tion in the Energy dialo g box. Setup → Models → Multiphase → Phases Edit... → Interaction... 1.Click the Interaction... butt on t o op en the Phase In teraction dialo g box (for e xample ,Figur e 26.60: The Phase In teraction D ialog Box for H eat Transf er (p.2234 )). 2233Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the E uler ian M odelFigur e 26.60: The P hase In teraction D ialo g Box for H eat Transf er 2.Click the Heat tab in the Phase In teraction dialo g box. 3.Selec t the desir ed c orrelation f or the Heat Transf er C oefficien t.The a vailable choic es will dep end up on wha t other mo dels y ou ha ve enabled . Note the f ollowing r egar ding the a vailable choic es: constan t-htc allows you t o sp ecify a c onstan t value f or the v olumetr ic hea t transf er coefficien t. nusselt-numb er allows you t o sp ecify a v alue f or the N usselt numb er fr om which the hea t transf er coefficien t will b e comput ed. gunn is frequen tly used f or E uler ian multiphase simula tions in volving a gr anular phase . ranz-marshall is frequen tly used f or E uler ian multiphase simula tions not in volving a gr anular phase . hughmar k is an e xtension of R anz-M arshall t o a wider r ange of R eynolds N umb er. tomiy ama is frequen tly used f or E uler ian multiphase simula tions of bubbly flo ws with r elatively lo w Reynolds numb er. none allows you t o ignor e the eff ects of hea t transf er b etween the t wo phases . user-defined allows you t o implemen t a c orrelation r eflec ting a mo del of y our choic e, through a user-defined func tion. two-resistanc e allows you t o indep enden tly sp ecify the hea t transf er coefficien t correlations f or the t wo phases .This setting is r ecommended when using the e vaporation-c ondensa tion mass tr ansf er mo del. fixed-t o-sa t-temp models hea t transf er when all of the hea t transf er to a phase in terface is used in mass tr ansf er. It as- sumes tha t the t emp erature at the To-Phase in the mass tr ansf er is equal t o the sa turation t emp erature. Note tha t this mo del only applies when one of the mass tr ansf er mo dels is enabled . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2234Modeling M ultiphase F lowslavieville-et-al is only a vailable within the t wo-resistanc e formula tion and c an b e used t o mo del the gas-in terface heat transf er coefficien t. It assumes tha t the gas phase r etains the sa turation t emp erature by rapid evaporation or c ondensa tion. zero-resistanc e is only a vailable within the t wo-resistanc e formula tion. It ma y be sp ecified f or one phase in which case tha t phase t emp erature is equal t o the in terfacial t emp erature. 4.Set the appr opriate ther mal b oundar y conditions .You will sp ecify the ther mal b oundar y conditions f or each individual phase on most b oundar ies, and f or the mix ture on some b oundar ies. See Cell Z one and Boundar y Conditions (p.835) for mor e inf ormation on b oundar y conditions , and Euler ian M odel (p.2135 ) for mor e inf ormation on sp ecifying b oundar y conditions f or a E uler ian multiphase c alcula tion. See Descr iption of H eat Transf er in the Theor y Guide for mor e inf ormation on hea t transf er in the framew ork of a E uler ian multiphase simula tion and the a vailable mo dels . 26.5.5. Using an A lgebr aic In terfacial A rea M odel If you ha ve chosen not t o solv e the tr ansp ort equa tion f or In terfacial A rea C oncentration ( Defining the Interfacial A rea C oncentration (p.2214 )), you c an selec t an algebr aic mo del t o estima te the in terfacial area fr om the sec ondar y phase diamet er sp ecified in the Secondar y Phase D ialog Box (p.3444 ).To cho ose an algebr aic in terfacial ar ea mo del p erform these st eps. 1.In the tr ee, right-click Phase In teractions (under Setup/M odels/M ultiphase ) and selec t Edit... to op en the Phase In teraction dialo g box (for e xample ,Figur e 26.61: The P hase In teraction D ialog Box for In ter- facial A rea (p.2235 )). Figur e 26.61: The P hase In teraction D ialo g Box for In terfacial A rea 2.In the Interfacial A rea tab , selec t the desir ed algebr aic mo del f or the Interfacial A rea. Note the f ollowing regar ding the a vailable choic es: ia-symmetr ic considers b oth the pr imar y and sec ondar y phase v olume fr actions in estima ting the in terfacial ar ea. ia-par ticle considers only the sec ondar y phase v olume fr action in estima ting the in terfacial ar ea. 2235Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the E uler ian M odelia-gr adien t considers the v olume fr action gr adien t at the in terface between t wo phases in estima ting the in terfacial area. Additional options ar e available if y ou ha ve enabled one of the b oiling mo dels . See Including the Boiling M odel (p.2241 ). See Interfacial A rea C oncentration in the Fluent Theor y Guide for details ab out the algebr aic in terfacial area mo dels . 26.5.6. Including the D ense D iscr ete Phase M odel If you ar e using the E uler ian multiphase mo del ( Setting U p the E uler ian M odel (p.2208 )), you ha ve the option of including the Dense D iscr ete Phase M odel (Dense D iscrete Phase M odel in the Theor y Guide ). Imp ortant •Enabling this mo del aut oma tically enables the DPM mo del. You will notic e tha t Interaction with C ontinuous P hase in the Discr ete Phase M odel dialo g box is enabled . •The D ense D iscrete Phase mo del is a vailable only with the Euler ian multiphase mo del. The limita tions tha t cur rently apply t o DPM and E uler ian multiphase mo dels also apply t o the D ense Discrete Phase mo del. See Limita tions of the E uler ian M odel in the Fluent Theor y Guide and Limita tions (p.1914 ) for limita tions tha t exist with the DPM and E uler ian multiphase mo dels . The r equir ed w ork flo w when using the dense discr ete phase mo del is as f ollows: 1.Set up the Multiphase M odel dialo g box (Figur e 26.62: The D ense D iscrete Phase M odel (p.2237 )) to include the dense discr ete phase mo del par amet ers. Setup → Models → Multiphase → Edit... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2236Modeling M ultiphase F lowsFigur e 26.62: The D ense D iscr ete Phase M odel a.Enable Dense D iscr ete Phase M odel under Euler ian P aramet ers. b.Set the Numb er of D iscr ete Phases tha t are pr esen t in y our c ase. 2.Open the Phases dialo g box, in or der t o define the phases . Setup → Models → Multiphase → Phases Edit... a.Define the discr ete phase , by selec ting the phase fr om the Phases selec tion list tha t is lab eled Discr ete Phase and click ing the Edit... butt on.Then set up the pr operties in the Discr ete Phase dialo g box that op ens, as sho wn in Figur e 26.63: The D iscrete Phase D ialog Box (p.2238 ). 2237Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the E uler ian M odelFigur e 26.63: The D iscr ete Phase D ialo g Box Note tha t for non-gr anular flo w, no additional inputs ar e requir ed her e (sinc e the ma terial is set aut oma tically in the back ground , and the diamet er is par t of the solution). b.To pr event par ticle c oncentration fr om b ecoming unph ysically high, enable Volume F raction A p- proaching C ontinuous F low Limit and sp ecify Transition F actor.The cr iterion of tr ansition fr om the standar d metho d to a sp ecial tr eatmen t is sp ecified as Transition F actor multiplied b y the theor etical close-pack ing limit f or mono-siz ed spher es ( ). If the par ticle v olume fr action e xceeds this transition v olume fr action, ANSY S Fluen t will apply a sp ecial tr eatmen t to the par ticle momen tum equa tion. For mor e inf ormation, refer to Dense D iscrete Phase M odel in the Fluent Theor y Guide . The default v alue f or the Transition F actor is 0.75, giving a tr ansition v olume fr action of 0.5625 (=0.75*3/4). Note tha t the Transition F actor is not limit ed t o a r ange b etween 0 and 1. In other w ords, you c an sp ecify v alues outside this r ange . For e xample , a value of 1.2 will giv e a transition v olume fr action of 0.9. You c an also sp ecify lo cally v ariable v alues using the DEFINE_PROPERTY user-defined macr o, dep ending on the lo cal par ticle siz e distr ibution, as an e xample . See DEFINE_PROPERTY UDFs in the Fluen t Customiza tion M anual for inf ormation ab out the DEFINE_PROPERTY . c.Define the pr imar y and sec ondar y phases , as descr ibed in Defining the P hases f or the E uler ian M od- el (p.2209 ). 3.Define the injec tions using the Injec tions dialo g box. Setup → Models → Discr ete Phase → Injec tions New... a.Create a new injec tion b y click ing the Create butt on in the Injec tions dialo g box, or edit an e xisting injec tion b y selec ting the injec tion fr om the Injec tions list and click ing the Set... butt on. b.In the Set Injec tion P roperties dialo g box tha t op ens ( Figur e 26.64: The S et Injec tion P roperties D ialog Box (p.2239 )), specify pr operties f or each injec tion as descr ibed in Setting Initial C onditions f or the Discrete Phase (p.1943 ) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2238Modeling M ultiphase F lowsFigur e 26.64: The S et Injec tion P roperties D ialo g Box Note Note tha t when the DDPM is used ,averaged-discr ete-phase-dr ag is aut oma tically selec ted f or the dr ag c oefficien t in the Drag tab of the Phase In teraction dialo g box.averaged-discr ete-phase-dr ag corresponds t o in Equa tion 18.418 in the Fluent Theor y Guide and indic ates tha t the in teraction b etween discr ete and fluid phases will b e comput ed based on a veraged v alues of fluid dr ag of all par ticles crossing the fluid c ell.That is, at each time st ep, the dr ag is e valua ted f or each par ticle using the dr ag la w tha t you ha ve selec ted in the Set injec tion P roperties dialo g box and then a veraged based on the r esidenc e time of each par ticle in the c ell. c.Selec t the discr ete phase fr om the Discr ete Phase D omain drop-do wn list. 4.Define the ma terial pr operties f or each injec tion. Setup → Materials 2239Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the E uler ian M odel26.5.6.1. Defining a Gr anular D iscr ete Phase To define a gr anular (tha t is, par ticula te) discr ete phase in an E uler ian multiphase c alcula tion, perform the f ollowing st eps: 1.Selec t the phase (f or e xample ,Discr ete Phase ) in the Phases list. 2.Click Edit... to op en the Discr ete Phase dialo g box (Figur e 26.65: The D iscrete Phase D ialog Box for a Granular P hase (p.2240 )). Figur e 26.65: The D iscr ete Phase D ialo g Box for a G ranular P hase 3.In the Discr ete Phase dialo g box, enter a Name for the phase . 4.Enable the Granular option. 5.Enable Volume F raction A ppr oaching P ack ing Limit to pr event the unlimit ed accumula tion of par ticles , which ar e op erating a t pack ing limit c onditions . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2240Modeling M ultiphase F lows6.Specify the Transition F actor as either a constan t or a user-defined func tion. The default v alue f or the Transition F actor is 0.75. The tr ansition cr iterion is based on the lo cal par ticle v olume fr action of the given discr ete phase and is sp ecified as a fac tor multiplied b y the maximum pack ing limit (also a user- specified v alue). For e xample , for a t ypic al gr anular phase with a maximum pack ing limit of 0.63, the transition v olume fr action is the pr oduc t of 0.75 and 0.63, which is equal t o 0.4725. You c an no w define all other fields of the discr ete phase in a similar manner t o tha t descr ibed in Defining a G ranular S econdar y Phase (p.2210 ). 26.5.7. Including the B oiling M odel If you ar e using the E uler ian multiphase mo del ( Setting U p the E uler ian M odel (p.2208 )), you ha ve the option of including the Boiling M odel (see Wall B oiling M odels in the Theor y Guide ). Note the f ollowing limita tions: •This mo del is only a vailable with the Euler ian multiphase mo del. •This mo del is only a vailable with the Pressur e-Based solv er. The r equir ed w ork flo w when using the b oiling mo del is as f ollows: 1.Open the Multiphase M odel dialo g box (Figur e 26.66: The B oiling M odel (p.2242 )). Setup → Models → Multiphase → Edit... 2241Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the E uler ian M odelFigur e 26.66: The B oiling M odel a.Enable Boiling M odel under Euler ian P aramet ers. b.Selec t RPI B oiling M odel,Non-equilibr ium B oiling , or Critical H eat Flux as the b oiling mo del option. Information ab out the thr ee options is a vailable in RPI M odel,Non-equilibr ium Sub cooled B oiling , and Critical H eat Flux in the Theor y Guide . c.Set the t otal Numb er of E uler ian P hases tha t are pr esen t in y our c ase.This c an c onsist of t wo phases: liquid and v apor, which ar e dir ectly in volved in b oiling mass tr ansf er; or it c an include “non-b oiling phases ” or “species“. If a sy stem c onsists of thr ee phases: liquid , vapor, and air , then the Numb er of Euler ian P hases will b e 3, wher e air is the non-b oiling phase . Note •To include the liquid v olume fr action eff ects, use the solve/set/multiphase-numer- ic/boiling-parameters/liquid-vof-factor text command .When this option is enabled , the hea t transf er coefficien ts of b oiling mo dels will b e multiplied b y the lo cal liquid volume fr action. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2242Modeling M ultiphase F lows•To include the thin film eff ects, use the solve/set/multiphase-numeric/boiling- parameters/thin-film text command .When enabled , this option will use Equa- tion 18.448 in the Fluent Theor y Guide in the c alcula tion. 2.Make sur e the ener gy option is enabled . Note The ener gy option will b e aut oma tically tur ned on when the b oiling mo del is enabled . Setup → Models → Energy On 3.Enable Gravity and set the Operating P ressur e in the Operating C onditions dialo g box. Imp ortant Make sur e gr avity is included when the b oiling mo del is used . 4.Choose one of the turbulenc e mo dels tha t is a vailable with the E uler ian multiphase mo del. Setup → Models → Visc ous → Edit... 5.Open the Create/Edit M aterials dialo g box and sp ecify the ma terial pr operties f or the liquid , vapor, solid , and an y other phases tha t ma y exist. Setup → Materials → Fluid → Create/Edit... Imp ortant For the liquid and v apor phases , the Standar d State Enthalp y must b e sp ecified , as it is used in the c omputa tion of the Latent Heat. 6.Open the Phases dialo g box, in or der t o define the phases . Setup → Models → Multiphase → Phases Edit... Define the liquid as the pr imar y phase b y selec ting the phase fr om the Phases selec tion list tha t is lab eled Primar y Phase and click ing the Edit... butt on. Define the v apor as the sec ondar y phase . In the Secondar y Phase dialo g box, the Diamet er is set t o boiling-dia by default , but y ou ha ve the option of setting it up as a constan t value or a user-defined func tion, as sho wn in Fig- ure 26.67: The S econdar y Phase D ialog Box (p.2244 ). 2243Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the E uler ian M odelFigur e 26.67: The S econdar y Phase D ialo g Box 7.Open the Phase In teraction dialo g box. Setup → Models → Multiphase → Phases Edit... → Interaction... a.In the Drag tab , selec t a dr ag sp ecific ation metho d. See Specifying the D rag F unction (p.2216 ) for a vailable dr ag options and their definitions . For b oiling flo ws,ishii is usually chosen. Figur e 26.68: The P hase In teraction D ialo g Box b.In the Lift tab , selec t mor aga ,tomiy ama ,saffman-mei ,legendr e-magnaudet , or user-defined . For boiling flo ws,tomiy ama is usually chosen. c.In the Wall L ubr ication tab , selec t antal-et-al ,tomiy ama-et-al ,frank ,hosok awa, or user-defined as descr ibed in Including the Wall L ubrication F orce (p.2221 ). For b oiling flo ws,antal-et-al is typic ally chosen. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2244Modeling M ultiphase F lowsd.In the Turbulen t Dispersion tab , selec t lopez-de-b ertodano ,simonin ,bur ns-et-al ,diffusion-in- vof, or user-defined as descr ibed in Including the Turbulen t Dispersion F orce (p.2224 ). For b oiling flows,lopez-de-b ertodano is typic ally chosen. e.In the Turbulen t Interaction tab , selec t troshk o-hassan ,sato, or simonin-et-al as descr ibed in In- cluding Turbulenc e Interaction S ource Terms (p.2231 ). For b oiling flo ws,troshk o-hassan is typic ally chosen. f.In the Heat tab , selec t ranz-marshall ,tomiy ama , or user-defined . For b oiling flo ws,ranz-marshall is usually chosen. g.In the Surface Tension tab , selec t constan t and en ter the desir ed v alue . h.In the Interfacial A rea tab , you ha ve four f ormula tions a vailable fr om which t o selec t: •ia-symmetr ic (see Equa tion 18.185 in the Theor y Guide ) •ia-par ticle (see Equa tion 18.184 in the Theor y Guide ) •ia-ishii (see Equa tion 18.188 in the Theor y Guide ).This option is only a vailable with the RPI mo del. •user-defined (see Example 4- C ustom In terfacial A rea in the Fluen t Customiza tion M anual ) For b oiling flo ws,ia-symmetr ic or ia-par ticle are usually chosen. i.In the Mass tab , set the Numb er of M ass Transf er M echanisms to 1 and mak e sur e the tr ansf er is always from the liquid t o the v apor phase . Selec t boiling under Mechanism .The Boiling M odel dialo g box will op en ( Figur e 26.69: The B oiling M odel D ialog Box (p.2246 )), wher e you will set the b oiling model par amet ers and the quenching mo del c orrections . 2245Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the E uler ian M odelFigur e 26.69: The B oiling M odel D ialo g Box i.Specify the Interfacial M odel C onstan ts and the Saturation Temp erature.The default v alues for the liquid and v apor in terface transf er coefficien ts ar e 1. Note •If you use the polynomial ,piec ewise-p olynomial , or piec ewise-linear option for Saturation Temp erature, the pr essur e-dep endenc y must b e sp ecified in terms of absolut e pr essur e. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2246Modeling M ultiphase F lows•If you selec ted the RPI B oiling M odel in the Multiphase M odel dialo g box, then you will not need t o sp ecify the Vapor-In terface Transf er C oeff., sinc e the v apor phase t emp erature is fix ed t o the sa turation t emp erature. ii.Under the Boiling M odel P aramet ers, selec t the Bubble D epar ture Diamet er tha t best descr ibes your mo del. Five options e xist: tolubinsk i-kostanchuk (the default setting), unal ,kocamusta- faogullar i-ishii ,constan t, and user-defined .The tolubinsk i-kostanchuk formula tion is descr ibed in Equa tion 18.436 in the Theor y Guide , the unal formula tion is descr ibed in Equa tion 18.438 in the Theor y Guide and the kocamustafao gullar i-Ishii formula tion is descr ibed in Equa tion 18.434 in the Theor y Guide . iii.Specify the Frequenc y of Bubble D epar ture.You c an cho ose the cole option (which is the default), or en ter a constan t value .The cole formula tion is descr ibed in Equa tion 18.432 in the Theor y Guide . iv.Specify the Nuclea tion S ite Densit y.You c an cho ose b etween lemmer t-cha wla (which is the default), kocamustafao gullar i-ishii . and user-defined .This quan tity is usually r epresen ted b y a correlation based on the w all sup erheat, descr ibed in Equa tion 18.433 in the Theor y Guide . Note It is r ecommended tha t when using the kocamustafao gullar i-ishii option, it should b e used f or b oth the Bubble D epar ture D iamet er and Nuclea tion S ite Densit y. v.Specify the Area Influenc e Coeff.The ar ea of influenc e is based on the bubble depar ture diamet er and the nuclea te sit e densit y, as defined in Equa tion 18.429 in the Theor y Guide .You ha ve a choic e of thr ee options when mo deling the ar ea of influenc e coefficien t:delv alle-k enning (which is the default and defined in Equa tion 18.430 in the Theor y Guide ,constan t, and user-defined . vi.The Quenching M odel C orrection addr esses the quenching t erm in the w all hea t flux par tition (descr ibed in Wall H eat Flux P artition in the Theor y Guide ).The quenching t erm in the w all hea t flux par tition mo dels the c yclic a veraged tr ansien t ener gy transf er related t o liquid filling the w all vicinit y after the bubble detachmen t with a p eriod and it is e xpressed as: (26.22) wher e is the liquid hea t conduc tivit y, is the p eriodic time , and is the liquid phase diffusivit y.The Bubble Waiting Time C oefficien t, , is a c oefficien t introduced t o correct the waiting time b etween depar tures of c onsecutiv e bubbles .The default v alue is 1, however you c an modify this v alue as needed , but it c an only b e sp ecified as a c onstan t. 2247Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the E uler ian M odelFrom Equa tion 26.22 (p.2247 ), you c an see tha t the quenching mo del is str ongly dep enden t on , which r esults in gr id-dep enden t solutions .To remed y this , two appr oaches ha ve been adopt ed in ANSY S Fluen t:Fixed Yplus Value and Fixed Liquid Temp erature. Note When the c alcula ted t emp erature in r egions a way from the w alls is lo wer than the Operating Temp erature (set in the Boussinesq P aramet ers group b ox in the Operating C onditions dialo g box), the solv er uses the op erating t emp erature for the quenching c orrection. vii.Enable the Correction M odel if you w ant to achie ve a c ertain le vel of gr id-indep endenc e in y our solution. If this option is disabled ,Equa tion 26.22 (p.2247 ) calcula tes the quench flux t erm without corrections . viii.Selec t Fixed Yplus Value if you w ant to use the lo garithmic f orm of the w all func tions t o estima te the liquid t emp erature at a fix ed Yplus v alue of 250, as pr oposed b y Egorov and M entor [30] (p.4006 ), inst ead of using the liquid t emp erature values in the near-w all c ells. Enter the Minimum Referenc e Temp erature, which limits the lo west v alue of the liquid t emp erature. It should not be lower than the liquid inlet t emp erature. Specify a Yplus Value . It is set t o 250 b y default. ix.If you selec t Fixed Liquid Temp erature, you c an cho ose fr om standar d,constan t, or user-defined for the Liquid Ref erenc e Temp erature.You will also need t o en ter the Minimum Ref erenc e Temp erature.The liquid t emp erature used t o comput e the quenching flux should usually b e between the inlet liquid t emp erature and the sa turation t emp erature. Note To lear n ho w to ho ok b oiling par amet er user-defined func tions , refer to DEFINE_BOILING_PROPERTY in the Fluen t Customiza tion M anual . 8.Set up the c onditions a t inlets , outlets , and ther mal c onditions f or w alls. Setup → Boundar y Conditions For the quenching w all hea t flux, Koncar et al. [61] (p.4008 ) have suggest ed tha t in or der t o avoid grid dep endenc e when c alcula ting the quenching hea t transf er, a fac tor tha t relates the t emp erature at a fix ed nor maliz ed distanc e (y+ = 250) t o the t emp erature at the near w all c ell must b e applied . Contact a t echnic al supp ort engineer f or mor e inf ormation. The w all b oiling mo dels ar e compa tible with thr ee diff erent wall b oundar ies: isother mal w all, spe- cified hea t flux, and sp ecified hea t transf er coefficien t (coupled w all b oundar y). Note The b oiling mo dels do not apply t o thin w alls. 9.Choose Coupled as the pr essur e-velocity coupling scheme . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2248Modeling M ultiphase F lowsSolution → Metho ds Note Although Phase C oupled SIMPLE is also a vailable , it is gener ally less r obust and is not recommended f or use in st eady cases in volving b oiling or mass tr ansf er. 10.The following solution str ategies ar e recommended f or b oiling mo del simula tions: Solution → Controls •Cour ant Numb er: use a v alue b etween 1 and 20 is r ecommended . As a first tr y, use a v alue of 10. •Explicit Relaxa tion F actors: use the default v alues of 1 f or Momen tum and Pressur e. •Vaporization M ass: use an under-r elaxa tion fac tor b etween 0.5 and 1. As a first tr y, use a v alue of 1. •Volume F raction : use an under-r elaxa tion fac tor b etween 0.3 and 0.5. •Turbulen t Kinetic E nergy: use an under-r elaxa tion fac tor b etween 0.3 and 0.8. •Turbulen t Visc osit y: use an under-r elaxa tion fac tor b etween 0.5 and 1.0. •Energy: use an under-r elaxa tion fac tor b etween 0.5 and 0.8. 26.5.8. Including the M ulti-F luid VOF M odel After y ou ha ve selec ted the E uler ian multiphase mo del ( Setting U p the E uler ian M odel (p.2208 )), you can enable the Multi-F luid VOF M odel (Multi-F luid VOF M odel in the Theor y Guide ). 2249Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the E uler ian M odelNote the f ollowing limita tions: •This mo del is only a vailable with the Euler ian multiphase mo del. •You c annot use this mo del with the Dense D iscr ete Phase M odel. After enabling Multi-F luid VOF, the Interface M odeling Options become a vailable , as descr ibed in Interface M odeling Type (p.2097 ).You c an selec t from Sharp,Dispersed , or h ybrid Sharp/D ispersed interface mo deling t o expose the most appr opriate discr etiza tion schemes f or y our simula tion. You can also sp ecify some additional time-ad vancemen t settings as descr ibed in Setting Time-D ependen t Paramet ers f or the Explicit Volume F raction F ormula tion (p.2179 ). The a vailable dr ag la ws dep end on y our selec tion f or Interface M odeling .Sharp interface mo deling supp orts only symmetr ic,anisotr opic-dr ag,user-defined , and none .Sharp/D ispersed interface Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2250Modeling M ultiphase F lowsmodeling supp orts all the r elevant drag la ws.Dispersed interface mo deling do es not supp ort aniso- tropic-dr ag, but supp orts all other r elevant drag la ws. Note Anisotr opic dr ag applic able t o free sur face mo deling is only c ompa tible with the Mixture turbulenc e mo del. If you w ant to use the anisotr opic dr ag la w, perform the f ollowing st eps: 1.Define the dr ag la w in the Phase In teraction dialo g box. Setup → Models → Multiphase → Phases Edit... → Interaction... 2.Click the Drag tab t o displa y the Drag C oefficien t inputs . 3.For each pair of phases , selec t the appr opriate dr ag la w fr om the c orresponding dr op-do wn list. •Selec t anisotr opic-dr ag when ther e is higher dr ag in the nor mal dir ection t o the in terface and lo wer drag in the tangen tial dir ection t o the in terface. For details ab out this dr ag la w, refer to Multi-F luid VOF Model in the Theor y Guide . To sp ecify the input par amet ers f or anisotr opic dr ag, you will need t o use the /solve/set/mp- mfluid-aniso-drag text command .The options f or an Anisotropic Drag Method of 0 (which is based on the symmetr ic dr ag), are as f ollows: Anisotropic Drag Method [0] Normal Interfacial Drag Friction Factor [1000000] Tangential Interfacial Drag Friction Factor [10] Length scale [0.0001] The options f or an Anisotropic Drag Method of 1 ar e as f ollows: Anisotropic Drag Method [0] 1 Viscosity option [2] Normal Interfacial Drag Friction Factor [1000000] Tangential Interfacial Drag Friction Factor [10] Length scale [0.0001] 2251Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the E uler ian M odel4.If you ha ve enabled Phase L ocaliz ed D iscr etiza tion in the Multiphase M odel dialo g box, click the Dis- cretiza tion tab t o enable the use of the Phase L ocaliz ed C ompr essiv e Scheme . For inf ormation ab out applying the v arious schemes , refer to Discretizing U sing the P hase L ocalized C ompr essiv e Scheme (p.2176 ). 26.6. Setting U p the Wet S team M odel After y ou ha ve enabled the densit y-based solv er in ANSY S Fluen t, you c an cho ose the w et st eam model (see Wet S team M odel Theor y in the Theor y Guide ) by op ening the Multiphase M odel dialo g box and selec ting the Wet S team option. Setup → Models → Multiphase → Edit... Figur e 26.70: The M ultiphase M odel D ialo g Box with the Wet S team M odel S elec ted This sec tion includes inf ormation ab out using y our o wn pr operty func tions and da ta with the w et st eam model. Solution settings and str ategies f or the w et st eam mo del c an b e found in Wet S team M od- el (p.2276 ). Postpr ocessing v ariables ar e descr ibed in Model-S pecific Variables (p.2279 ). This sec tion is or ganiz ed as f ollows: 26.6.1. Using U ser-D efined Thermodynamic Wet Steam P roperties 26.6.2. Writing the U ser-D efined Wet Steam P roperty Functions (UD WSPF) 26.6.3. Compiling Your UD WSPF and B uilding a S hared Libr ary File 26.6.4. Loading the UD WSPF S hared Libr ary File 26.6.5. UDWSPF Example 26.6.1. Using U ser-D efined Thermodynamic Wet S team P roperties ANSY S Fluen t allo ws you t o use y our o wn pr operty func tions and da ta with the w et st eam mo del. This is achie ved with user-defined w et st eam pr operty func tions (UD WSPF). These user-defined func tions ar e wr itten in the C pr ogramming language and ther e is a c ertain pr o- gramming f ormat tha t must b e used so tha t you c an build a succ essful libr ary tha t can b e loaded in to the ANSY S Fluen t code. The f ollowing is the pr ocedur e for using the user-defined w et st eam pr operty func tions (UD WSPF): 1.Define the w et st eam equa tion of sta te and all r elated ther modynamic and tr ansp ort property equa tions . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2252Modeling M ultiphase F lows2.Create a C sour ce code file tha t conforms t o the f ormat defined in this sec tion. 3.Start ANSY S Fluen t and set up y our c ase file in the usual w ay. 4.Turn on the w et st eam mo del. 5.Compile y our UD WSPF C func tions and build a shar ed libr ary file using the t ext user in terface. define → models → multiphase → wet-steam → compile-user-defined-wetsteam- functions 6.Load y our newly cr eated UD WSPF libr ary using the t ext user in terface. define → models → multiphase → wet-steam → load-unload-user-defined-wet- steam-library 7.Run y our c alcula tion. Imp ortant Note tha t the UD WSPF c an only b e used when the w et st eam mo del is selec ted.Therefore, the UD WSPF ar e available f or use with the densit y-based solv er only . 26.6.2. Writing the U ser-D efined Wet S team P roperty Func tions (UD WSPF) Creating a UD WSPF C func tion libr ary is r easonably str aigh tforward: •The c ode must c ontain the udf.h file inclusion dir ective at the b eginning of the sour ce code.This allo ws the definitions f or DEFINE macr os and other ANSY S Fluen t func tions t o be acc essible dur ing the c ompila tion process. •The c ode must include a t least one in the UDF’ s DEFINE func tions (tha t is DEFINE_ON_DEMAND ) to be able t o use the c ompiled UDFs utilit y. •Any values tha t are passed t o the solv er b y the UD WSPF or r etur ned b y the solv er to the UD WSPF ar e as- sumed t o be in SI units . •You must use the pr inciple set of user-defined w et st eam pr operty func tions in y our UD WSPF libr ary, as descr ibed in the list tha t follows.These func tions ar e the mechanism b y which y our ther modynamic property da ta is tr ansf erred t o the ANSY S Fluen t solv er. The f ollowing lists the user-defined w et st eam pr operty func tion names and ar gumen ts, as w ell as a shor t descr iption of their func tions . Function inputs fr om the ANSY S Fluen t solv er consist of one or mor e of the f ollowing v ariables: T = t emp erature ( ), P = pr essur e ( ), and = v apor-phase densit y ( ). •void wetst_init(Domain *domain) This will b e called when y ou load the UD WSPF.You use it t o initializ e wet st eam mo del c onstan ts or y our o wn mo del c onstan ts. It retur ns nothing . •real wetst_satP(real T) 2253Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the Wet Steam M odelThis is the sa turated pr essur e func tion, which tak es on t emp erature in K and r etur ns sa turation pressur e in P a. •real wetst_satT(real P, real T) This is the sa turated t emp erature func tion, which tak es on pr essur e in P a and a star ting guess t em- perature in K and r etur ns sa turation t emp erature in K. •real wetst_eosP(real rho, real T) This is the equa tion of sta te, which tak es on v apor densit y in k g/m3 and Temp erature in K and r etur ns pressur e in P a. •real wetst_eosRHO(real P, real T) This is the equa tion of sta te, which tak es on pr essur e in P a and t emp erature in K and r etur ns v apor densit y in k g/m3. •real wetst_cpv(real T, real rho) This is the v apor sp ecific hea t at constan t pressur e, which tak es on t emp erature in K and v apor densit y in k g/m3 and r etur ns sp ecific hea t at constan t pressur e in J/k g/K. •real wetst_cvv(real T, real rho) This is the v apor sp ecific hea t at constan t volume , which tak es on t emp erature in K and v apor densit y in k g/m3 and r etur ns sp ecific hea t at constan t volume in J/k g/K. •real wetst_hv(real T,real rho) This is the v apor sp ecific en thalp y, which tak es on t emp erature in K and v apor densit y in k g/m3 and retur ns sp ecific en thalp y in J/Kg . •real wetst_sv(real T, real rho) This is the v apor sp ecific en tropy, which tak es on t emp erature in K and v apor densit y in k g/m3 and retur ns sp ecific en tropy in J/Kg/K. •real wetst_muv(real T, real rho) This is the v apor d ynamic visc osity, which tak es on t emp erature in K and v apor densit y in k g/m3 and r etur ns visc osity in k g/m/s . •real wetst_ktv(real T, real rho) This is the v apor ther mal c onduc tivit y, which tak es on t emp erature in K and v apor densit y in k g/m3 and r etur ns ther mal c onduc tivit y in W/m/K. •real wetst_rhol(real T) This is the sa turated liquid densit y, which tak es on t emp erature in K and r etur ns liquid densit y in kg/m3. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2254Modeling M ultiphase F lows•real wetst_cpl(real T) This is the sa turated liquid sp ecific hea t at constan t pressur e, which tak es on t emp erature in K and retur ns liquid sp ecific hea t in J/k g/K. •real wetst_mul(real T) This is the liquid d ynamic visc osity, which tak es on Temp erature in K and r etur ns d ynamic visc osity in kg/m/s . •real wetst_ktl(real T) This is the liquid ther mal c onduc tivit y, which tak es on t emp erature in K and r etur ns ther mal c on- duc tivit y in W/m/K. •real wetst_surft(real T) This is the liquid sur face tension, which tak es on Temp erature in K and r etur ns sur face tension N/m. At the end of the c ode y ou must define a str ucture of t ype WS_Functions whose memb ers ar e pointers t o the pr inciple func tions list ed pr eviously .The str ucture is of t ype WS_Functions and its name is WetSteamFunctionList . UDF_EXPORT WS_Functions WetSteamFunctionList = { wetst_init, /*initialization function*/ wetst_satP, /*Saturation pressure*/ wetst_satT, /*Saturation temperature*/ wetst_eosP, /*equation of state*/ wetst_eosRHO, /*equation of state*/ wetst_hv, /*vapor enthalpy*/ wetst_sv, /*vapor entropy*/ wetst_cpv, /*vapor isobaric specific heat*/ wetst_cvv, /*vapor isochoric specific heat*/ wetst_muv, /*vapor dynamic viscosity*/ wetst_ktv, /*vapor thermal conductivity*/ wetst_rhol, /*sat. liquid density*/ wetst_cpl, /*sat. liquid specific heat*/ wetst_mul, /*sat. liquid viscosity*/ wetst_ktl, /*sat. liquid thermal conductivity*/ wetst_surft /*liquid surface tension*/ }; 26.6.3. Compiling Your UD WSPF and Building a S hared Libr ary File This sec tion pr esen ts the st eps y ou will need t o follow to compile y our UD WSPF C c ode and build a shar ed libr ary file .This pr ocess r equir es the use of a C c ompiler . For mor e details on c ompiler r equir e- men ts, see Compilers in the Fluent C ustomization Manual . Imp ortant To use the UD WSPF y ou will need t o first build the UD WSPF libr ary by compiling y our UD- WSPF C c ode and then loading the libr ary into the ANSY S Fluen t code. The UD WSPF shar ed libr ary is built in the same w ay tha t the ANSY S Fluen t executable itself is built. Internally , a scr ipt c alled Makefile is used t o in voke the sy stem C c ompiler t o build an objec t code library tha t contains the na tive machine language tr ansla tion of y our higher-le vel C sour ce code.This shar ed libr ary is then loaded in to ANSY S Fluen t (either a t run time or aut oma tically when a c ase file 2255Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the Wet Steam M odelis read) b y a pr ocess c alled dynamic loading .The objec t libr aries ar e sp ecific t o the c omput er ar chitecture being used , as w ell as t o the par ticular v ersion of the ANSY S Fluen t executable b eing r un.The libr aries must , ther efore, be rebuilt an y time ANSY S Fluen t is up graded , when the c omput er’s op erating sy stem level changes , or when the job is r un on a diff erent type of c omput er. The gener al pr ocedur e for c ompiling UD WSPF C c ode is as f ollows: 1.Place the UD WSPF C c ode in y our w orking dir ectory (tha t is, wher e your c ase file r esides). 2.Launch ANSY S Fluen t. 3.Read y our c ase file in to ANSY S Fluen t. 4.You c an no w compile y our UD WSPF C c ode and build a shar ed libr ary file using the c ommands pr ovided in the t ext command in terface (TUI): a.Selec t the define/models/multiphase/wet-steam menu it em. define → models → multiphase → wet-steam If the Wet S team mo del has not b een enabled y et, use the f ollowing TUI c ommands t o enable it: define/models/multiphase/wet-steam> enable? Enable wet steam model? [no] yes b.Selec t the compile-user-defined-wetsteam-functions option. c.Enter the c ompiled UD WSPF libr ary name . The name giv en her e is the name of the dir ectory wher e the shar ed libr ary (for e xample ,libudf ) will r eside . For e xample , if y ou pr ess Enter then a dir ectory should e xist with the name libudf , and this dir ectory will c ontain libr ary file c alled libudf . If, however, you t ype a new libr ary name such as mywetsteam , then a dir ectory called mywetsteam will b e created and it will contain the libr ary libudf . d.Continue on with the pr ocedur e when pr ompt ed. e.Enter the C sour ce file names . Imp ortant Ideally y ou should plac e all of y our func tions in to a single file . However, you c an split them in to separ ate files if desir ed. f.Enter the header file names , if applic able . If you do not ha ve an e xtra header file , then pr ess Enter when pr ompt ed. ANSY S Fluen t will then star t compiling the UD WSPF C c ode and put it in the appr opriate ar chi- tecture dir ectory. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2256Modeling M ultiphase F lows26.6.4. Loading the UD WSPF S hared Libr ary File To load the UD WSPF libr ary, perform the f ollowing st eps: •Go to the define/models/multiphase/wet-steam menu it em in the t ext user in terface. define → models → multiphase → wet-steam •Selec t the load-unload-user-defined-wetsteam-library option and f ollow the pr ocedur e when pr ompt ed. If the loading of the UD WSPF libr ary is succ essful, you will see a message similar t o the f ollowing: Opening user-defined wet steam library "libudf"... Library "libudf/lnamd64/2d/libudf.so" opened Setting material properties to Wet-Steam... Initializing user defined material properties... 26.6.5. UD WSPF E xample This sec tion descr ibe a simple UD WSPF.You c an use this e xample as the basis f or y our o wn UD WSPF code. For appr oxima te calcula tions a t low pr essur e, the simple ideal-gas equa tion of sta te and c onstan t isobar ic sp ecific hea t is assumed and used .The pr operties a t the sa turated liquid line and the sa turated vapor line used in this e xample ar e similar t o the one used b y ANSY S Fluen t. /**********************************************************************/ /* User Defined Wet Steam Properties: EOS : Ideal Gas Eq. Vapor Sat. Line : W.C.Reynolds tables (1979) Liquid Sat. Line: E. Eckert & R. Drake book (1972) Use ideal-gas EOS with Steam properties to model wet steam condensation in low pressure nozzle Author: L. Zori Date : Jan. 29 2004 */ /**********************************************************************/ #include "udf.h" #include "stdio.h" #include "ctype.h" #include "stdarg.h" /*Global Constants for this model*/ real ws_TPP = 338.150 ; real ws_aaa = 0.01 ; real cpg = 1882.0;/* Cp-vapor at low-pressure region*/ DEFINE_ON_DEMAND(I_do_nothing) { /* This is a dummy function to allow us to use */ /* the Compiled UDFs utility */ } void wetst_init(Domain *domain) { /* You must initialize these material property constants. they will be used in the wet steam model in fluent */ ws_Tc = 647.286 ;/*Critical Temp. */ 2257Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p the Wet Steam M odel ws_Pc = 22089000.00 ;/*Critical Pressure */ mw_f = 18.016 ;/*fluid droplet molecular weight (water) */ Rgas_v = 461.50 ;/*vapor Gas Const*/ } real wetst_satP(real T) { real psat; real SUM=0.0; real pratio; real F; real a1 = -7.41924200 ; real a2 = 2.97210000E-01; real a3 = -1.15528600E-01; real a4 = 8.68563500E-03; real a5 = 1.09409899E-03; real a6 = -4.39993000E-03; real a7 = 2.52065800E-03; real a8 = -5.21868400E-04; if (T > ws_Tc) T = ws_Tc ; F = ws_aaa*(T - ws_TPP) ; SUM = a1 + F*(a2+ F*(a3+ F*(a4+ F*(a5+ F*(a6+ F*(a7+ F*a8)))))) ; pratio = (ws_Tc/T - 1.0)*SUM; psat = ws_Pc *exp(pratio) ; return psat; /*Pa */ } real wetst_satT(real P, real T) { real tsat; real dT, dTA,dTM,dP,p1,p2,dPdT; real dt = 1.e-4; int i ; for (i=0; i<25; ++i) { if (T > ws_Tc) T = ws_Tc-0.5; p1= wetst_satP(T) ; p2= wetst_satP(T+dt) ; dPdT = (p2-p1)/dt; dP = P - p1 ; dT = dP/dPdT ; dTA = fabs(dT); T = T + dT; if (fabs(dT) ws_Tc) T = ws_Tc ; for(ii=0;ii 8;++ii) { i = ii+1 ; SUM += D[ii] * pow((1.0 - T/ws_Tc), i/3.0); } rhol = rhoc*(1.0+SUM); return rhol; /* (Kg/m3) */ } real wetst_cpl(real T) { real cpl; real a1= -36571.6 ; real a2= 555.217 ; real a3= -2.96724 ; real a4= 0.00778551; real a5= -1.00561e-05; real a6= 5.14336E-09; if (T > ws_Tc) T = ws_Tc ; cpl = a1 + T*(a2+ T*(a3+ T*(a4+ T*(a5+ T*a6)))) ; return cpl; /* (J/Kg/K) */ } real wetst_mul(real T) { real mul; real a1= 0.530784; real a2= -0.00729561; real a3= 4.16604E-05 ; real a4= -1.26258E-07; real a5= 2.13969E-10; real a6= -1.92145E-13; real a7= 7.14092E-17; if (T > ws_Tc) T = ws_Tc ; mul = a1 + T*(a2+ T*(a3+ T*(a4+ T*(a5+ T*(a6+ T*a7))))) ; return mul; /* (Kg/m/s) */ } real wetst_ktl(real T) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2260Modeling M ultiphase F lows { real ktl; real a1= -1.17633; real a2= 0.00791645; real a3= 1.48603E-05; real a4= -1.31689E-07; real a5= 2.47590E-10; real a6= -1.55638E-13; if (T > ws_Tc) T = ws_Tc ; ktl = a1 + T*(a2+ T*(a3+ T*(a4+ T*(a5+ T*a6)))) ; return ktl; /* W/m/K */ } real wetst_surft(real T) { real sigma; real Tr; real a1= 82.27 ; real a2= 75.612; real a3= -256.889 ; real a4= 95.928; if (T > ws_Tc) T = ws_Tc ; Tr = T/ws_Tc ; sigma = 0.001*(a1 + Tr*(a2+ Tr*(a3+ Tr*a4))) ; return sigma ;/* N/m */ } /* do not change the order of the function list */ UDF_EXPORT WS_Functions WetSteamFunctionList = { wetst_init, /*initialization function*/ wetst_satP, /*Saturation pressure*/ wetst_satT, /*Saturation temperature*/ wetst_eosP, /*equation of state*/ wetst_eosRHO, /*equation of state*/ wetst_hv, /*vapor enthalpy*/ wetst_sv, /*vapor entropy*/ wetst_cpv, /*vapor isobaric specific heat*/ wetst_cvv, /*vapor isochoric specific heat*/ wetst_muv, /*vapor dynamic viscosity*/ wetst_ktv, /*vapor thermal conductivity*/ wetst_rhol, /*sat. liquid density*/ wetst_cpl, /*sat. liquid specific heat*/ wetst_mul, /*sat. liquid viscosity*/ wetst_ktl, /*sat. liquid thermal conductivity*/ wetst_surft /*liquid surface tension*/ }; /**********************************************************************/ 26.7. Solution S trategies f or M ultiphase M odeling Imp ortant Double P recision is recommended f or all multiphase c ases . For additional inf ormation, see the f ollowing sec tions: 26.7.1. Coupled S olution f or Euler ian M ultiphase F lows 26.7.2. Coupled S olution f or VOF and M ixture Multiphase F lows 2261Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Solution S trategies f or M ultiphase M odeling26.7.3. Selec ting the P ressur e-Velocity Coupling M etho d 26.7.4. Controlling the Volume F raction C oupled S olution 26.7.5. VOF M odel 26.7.6. Mixture Model 26.7.7. Euler ian M odel 26.7.8. Wet Steam M odel 26.7.1. Coupled S olution f or E uler ian M ultiphase F lows In multiphase flo w, the phasic momen tum equa tions , the shar ed pr essur e, and the phasic v olume fraction equa tions ar e highly c oupled .Traditionally , these equa tions ha ve been solv ed in a segr egated fashion using some v ariation of the SIMPLE algor ithm t o couple the shar ed pr essur e with the momen tum equa tions .This is a ttained b y eff ectively tr ansf orming the t otal c ontinuit y into a shar ed pr essur e.The ANSY S Fluen t Phase C oupled SIMPLE algor ithm has b een succ essfully implemen ted and solv es a wide r ange of multiphase flo ws. However, coupling the linear ized sy stem of equa tions in an implicit manner w ould off er a mor e robust alt ernative to the segr egated appr oach. One of the fundamen tal pr oblems is tha t the r esulting ma trix is not symmetr ic and tha t the c ontinuit y constr aint ma y contribut e to a z ero diagonal blo ck, mak ing the solution difficult t o obtain. One w ay to cir cum vent this pr oblem is t o use dir ect solv ers, but these ar e too expensiv e for lar ge industr ial cases . In addition, we need t o avoid a z ero diagonal, resulting fr om the c ontinuit y constr aint, and lik e the segr egated solv er, we need t o constr uct a pr essur e correction equa tion. In multiphase , we also have the additional pr oblem of the v anishing phase , which f or the c oupled solv er is imp ortant to ensur e some c ontinuit y in the c oefficien ts. Like the Phase C oupled , we use a R hie and C how type of scheme to calcula te volume flux es and t o pr ovide pr oper coupling b etween v elocity and pr essur e, ther eby avoiding unph ysical oscilla tions . Consider a single-phase sy stem and let us denot e the v elocity correction c omp onen ts in the thr ee Cartesian dir ections b y , , and with denoting the shar ed pr essur e correction. These ar e discr ete variables and c an b e expressed in the f orm .The linear sy stem tha t is gener ated b y the single- phase c oupled solv er is of the f orm (26.23) For a nota tion in c omp onen t form (26.24) Now let us c onsider a multiphase sy stem of n-phases and denot e the phasic v elocity correction c om- ponen ts in the thr ee C artesian dir ections b y , , and wher e the subscr ipt represen ts the phase nota tion, denot es the shar ed pr essur e correction and denot es the v olume fr action c orrection (ANSY S Fluen t can solv e in b oth c orrection f orm for v elocity and v olume fr action and non-c orrection form). For simplicit y the ma trix will b e sho wn f or two phases .The v ector solution is of the f orm or in a shor ter nota tion .The linear sy stem w ould b e an e x- tension of the one gener ated b y the c oupled solv er sho wn b y Equa tion 26.23 (p.2262 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2262Modeling M ultiphase F lows(26.25) This sy stem c an b e easily gener alized t o phases .The c omp onen ts of this ma trix ar e also ma trices. For lar ge pr oblems w e need t o resor t to iterative solv ers.The ANSY S Fluen t AMG C oupled solv er with an IL U smo other has pr oved t o be a r obust metho d. Most c oupled solv ers also need a pseudo st epping metho d, adding mor e diagonal dominanc e to the ma trix. Our metho d her e is t o use under-r elaxa tion factors f or momen tum, which is equiv alen t to time st epping in st eady flo ws. Similar t o tha t of the single phase , we ha ve in troduced a st eady Courant Numb er inst ead of an under-r elaxa tion f or v elocities . Having this c ontrol is imp ortant when using sec ond or der numer ical schemes in the c onvective terms. For the sak e of simplicit y, input par amet ers f or the Coupled solv er ar e similar t o the single-phase solv er.We ha ve the options f or solving the whole sy stem including v olume fr action, or t o treat the volume fr action solution in a segr egated manner while pr eser ving the pr essur e-velocity coupling f or all phases . Imp ortant Equa tions in multiphase ar e mor e str ongly link ed than single phase and gener ally ma y need mor e under-r elaxa tion, henc e using the same v alues as single phase ma y not b e ideal. A low C ourant numb er w ould stabiliz e the solution. See Selec ting the P ressur e-Velocity Coupling M etho d (p.2264 ) for inf ormation ab out applying the v arious algor ithms . 26.7.2. Coupled S olution f or VOF and M ixture M ultiphase F lows We ha ve the option of solving the multiphase sy stem f or VOF and mix ture multiphase mo dels in the following w ays: •Solving the c ontinuit y and momen tum equa tions in a c oupled manner (see Coupled A lgor ithm in the Theor y Guide ) and solving the v olume fr action equa tion in a segr egated manner . •Solving the v olume fr action equa tion in a c oupled manner along with the c ontinuit y and momen tum equa tions . Solving the v olume fr action equa tion in a c oupled manner r equir es discr etiza tion of the v olume fr action equa tion in the c orrection f orm along with the discr etiza tion of the c ontinuit y and momen tum equa tion, as discussed in Coupled A lgor ithm in the Theor y Guide . The v olume fr action equa tion c ould b e represen ted in the discr etized f orm as (26.26) The o verall sy stem of equa tions af ter b eing tr ansf ormed t o the c orrection f orm could b e represen ted as 2263Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Solution S trategies f or M ultiphase M odeling(26.27) For a 2D c ase and t wo-phase flo w, the sy stem c ould b e expanded as f ollows: (26.28) and the unk nown and r esidual v ectors ha ve the f orm (26.29) (26.30) wher e = c oefficien t ma trix = solution v ector = residual v ector = pr essur e correction = v elocity corrections = v olume fr action c orrection 26.7.3. Selec ting the P ressur e-Velocity Coupling M etho d The settings tha t are available in the Solution M etho ds task page (see Figur e 26.71: The S olution Metho ds Task P age D ispla ying The P ressur e-Velocity Coupling Options (p.2266 )) for solving the c oupled system of equa tions ar ising in multiphase flo ws are: Schemes •Phase C oupled SIMPLE (Euler ian multiphase) •PISO (VOF and mix ture) •SIMPLE (VOF and mix ture) •SIMPLEC (VOF and mix ture) •Coupled (all multiphase mo dels) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2264Modeling M ultiphase F lowsOptions •Coupled with Volume F ractions (all multiphase mo dels e xcept dr ift-flux) •Solve N-P hase Volume F raction E qua tions (mix ture and E uler ian mo dels) The PISO ,SIMPLE , and SIMPLEC schemes apply t o the VOF and mix ture mo dels and ar e discussed in Pressur e-Velocity Coupling in the Theor y Guide . The Phase C oupled SIMPLE (PC-SIMPLE) is an e xtension of the SIMPLE algor ithm [88] (p.4009 ) to multiphase flo ws.The v elocities ar e solv ed c oupled b y phases in a segr egated fashion. Fluxes ar e re- constr ucted a t the fac es of the c ontrol volume and then a pr essur e correction equa tion is built based on t otal c ontinuit y.The c oefficien ts of the pr essur e correction equa tions c ome fr om the c oupled p er phase momen tum equa tions .This metho d has pr oven t o be robust and it is the only metho d available for all pr evious v ersions of ANSY S Fluen t. The Coupled scheme (also k nown as Multiphase C oupled in pr evious ANSY S Fluen t versions) solv es all equa tions f or phase v elocity corrections and shar ed pr essur e correction simultaneously [39] (p.4007 ). These metho ds inc orporate the lif t forces and the mass tr ansf er terms implicitly in to the gener al ma trix. This metho d w orks v ery efficien tly in st eady-sta te situa tions , or f or tr ansien t problems when lar ger time st eps ar e requir ed. The Coupled with Volume F ractions option (also k nown as Full M ultiphase C oupled in pr evious ANSY S Fluen t versions) c ouples v elocity corrections , shar ed pr essur e corrections , and the c orrection for v olume fr action simultaneously .Theor etically, it should b e mor e efficien t, however it ma y ha ve some dr awbacks in r obustness and CPU time usage .The r obustness issue st ems fr om the lack of c ontrol of the solution of the v olume fr action equa tion. The c ontinuit y constr aint (sum of all v olume fr actions equals 1, and individual v alues limit ed b etween z ero and one) c annot b e enf orced e xactly dur ing inner solv er it erations , and sligh t variations fr om the ph ysical limits ma y lead t o div ergenc e. Resear ch is ongoing in this ar ea t o impr ove the metho d.The metho d is ad vantageous f or het erogeneous mass transf er when a lo w C ourant numb er is giv en; it also w orks w ell in dilut e situa tions . The Volume F raction C oupling M etho d aims t o achie ve a fast er st eady-sta te solution c ompar ed t o the segr egated metho d of solving equa tions . It ma y not b e a suitable option f or tr ansien t applic ations due to the signific ant overhead in CPU time c ompar ed t o the segr egated metho d, unless it is r un with a larger time st ep siz e. Note The Coupled with Volume F ractions option is a vailable in the in terface af ter y ou ha ve selec ted Coupled from the Scheme drop-do wn list f or Pressur e-Velocity Coupling . For st eady-sta te cases , the Pseudo Transien t option will b e enabled aut oma tically when y ou enable the Coupled with Volume F ractions option f or the VOF and mix ture models . 2265Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Solution S trategies f or M ultiphase M odelingFigur e 26.71: The S olution M etho ds Task P age D ispla ying The P ressur e-Velocity Coupling Options 26.7.3.1. Limitations and R ecommendations of the C oupled with Volume F raction Options for the VOF and M ixture Mo dels The c oupled with v olume fr actions option has the f ollowing limita tions: •It is not a vailable when Slip Velocity is enabled f or the Mixture multiphase mo del. •It is not supp orted when using the S inghal-E t-Al cavitation mo del. •It is not supp orted when the Explicit formula tion f or v olume fr action is selec ted. Recommended uses of the c oupled with v olume fr actions option: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2266Modeling M ultiphase F lows•The P seudo-tr ansien t solv er is r ecommended f or st eady-sta te calcula tions . •It is r ecommended tha t you use lo wer under-r elaxa tion fac tors f or momen tum f or higher or der schemes . •For mar ine applic ations , it is r ecommended tha t you use a lo w-or der v ariant or h ybrid tr eatmen t for the R hie-cho w fac e flux in terpolation (see High-Or der R hie-C how Face Flux In terpolation (p.2272 )). •It is r ecommended tha t you use the e xpert text command options solve/set/coupled-vof- expert for b etter stabilit y when using the VOF mo del (see solve/ in the Text Command List ). 26.7.3.2. Solving N-P hase Volume F raction E quations For a multiphase flo w, the sum of the phase v olume fr actions must alw ays equal 1. By default , Fluen t enforces this c onstr aint by solving the v olume fr action equa tions f or each of the sec ondar y phases and then setting the v olume fr action of the pr imar y phase t o the c omplemen t. In certain c ases , wher e poor c onvergenc e and/or mass imbalanc e ar e obser ved, enabling Solve N- Phase Volume F raction E qua tions ma y impr ove solutions , although in pr actice the r esults obtained from using this option ar e case dep enden t. If selec ted, this option will solv e all v olume fr action equa tions , including b oth pr imar y and sec ondar y phases .The r esulting phase v olume fr actions ar e then sc aled in or der t o sa tisfy the r equir emen t of summing t o 1. This appr oach is mor e computa tionally expensiv e than the default appr oach and , in gener al, should not b e nec essar y for the simula tion. Note The Solve N-P hase Volume F raction E qua tions option is not a vailable f or the Volume of F luid mo del or Euler ian with Multi-F luid VOF M odel enabled . 26.7.4. Controlling the Volume F raction C oupled S olution When using the Coupled with Volume F ractions scheme , you will need t o sp ecify the f ollowing in the Solution C ontrols task page (see Figur e 26.72: The S olution C ontrols Task P age D ispla ying the Coupled Volume F raction M etho d for the VOF and M ixture M odels (p.2268 )): •VOF and M ixture M ultiphase M odel: –For st eady-sta te cases using the pseudo tr ansien t solv er, specify the Volume F raction C our ant Numb er, and the Pseudo Transien t Explicit Relaxa tion F actors.The Pseudo Transien t Explicit Relaxa tion F actors are descr ibed in Setting P seudo Transien t Explicit R elaxa tion F actors (p.2619 ). Note The Pseudo Transien t Explicit Relaxa tion F actors for the Volume F raction is set t o 0.5 b y default. 2267Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Solution S trategies f or M ultiphase M odeling–For tr ansien t cases or st eady-sta te cases not in volving the pseudo tr ansien t solv er, enter the Flow Cour ant Numb er, the Volume F raction C our ant Numb er,Explicit Relaxa tion F actors, and the Under-Relaxa tion F actors. Note The Volume F raction is set as an Explicit Relaxa tion F actor and is 0.75 b y default. Figur e 26.72: The S olution C ontrols Task P age D ispla ying the C oupled Volume F raction Metho d for the VOF and M ixture M odels •Euler ian M ultiphase M odel: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2268Modeling M ultiphase F lowsFor st eady-sta te cases using the pseudo tr ansien t solv er, specify the Pseudo Transien t Explicit Relaxa tion F actors as descr ibed in Setting P seudo Transien t Explicit R elaxa tion F actors (p.2619 ). Note The Pseudo Transien t Explicit Relaxa tion F actors for the Volume F raction is set t o 0.5 b y default.– –For tr ansien t cases or st eady-sta te cases not in volving the pseudo tr ansien t solv er, enter the Flow Cour ant Numb er, the Explicit Relaxa tion F actors, and the Under-Relaxa tion F actors. Note The under-r elaxa tion f or Volume F raction is set b y using an implicit Under-Relax- ation F actor, rather than a Volume F raction C our ant Numb er, and is 0.5 b y de- fault. 2269Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Solution S trategies f or M ultiphase M odelingFigur e 26.73: The S olution C ontrols Task P age D ispla ying the C oupled Volume F raction Metho d for the E uler ian M ultiphase M odel 26.7.5. VOF M odel Several recommenda tions f or impr oving the accur acy and c onvergenc e of the VOF solution ar e presen ted her e. 26.7.5.1. Setting the R efer enc e Pressur e Location The sit e of the r eference pr essur e can b e mo ved t o a lo cation tha t will r esult in less r ound-off in the pressur e calcula tion. By default , the r eference pr essur e lo cation is the c enter of the c ell a t or closest to the p oint (0,0,0). You c an mo ve this lo cation b y sp ecifying a new Referenc e Pressur e Location in the Operating C onditions D ialog Box (p.3470 ). Setup → Cell Z one C onditions → Operating C onditions ... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2270Modeling M ultiphase F lowsThe p osition tha t you cho ose should b e in a r egion tha t will alw ays contain the least dense of the fluids (f or e xample , the gas phase , if y ou ha ve a gas phase and one or mor e liquid phases). This is because v ariations in the sta tic pr essur e ar e lar ger in a mor e dense fluid than in a less dense fluid , given the same v elocity distr ibution. If the z ero of the r elative pr essur e field is in a r egion wher e the pressur e variations ar e small, less r ound-off will o ccur than if the v ariations o ccur in a field of lar ge nonz ero values .Thus in sy stems c ontaining air and w ater, for e xample , it is imp ortant tha t the r eference pressur e lo cation b e in the p ortion of the domain filled with air r ather than tha t filled with w ater. 26.7.5.2. Pressur e Int erp olation Scheme For all VOF c alcula tions , you should use the b ody-force-weigh ted pr essur e in terpolation scheme or the PREST O! scheme . Solution → Controls 26.7.5.3. Discr etization Scheme S elec tion The a vailabilit y of discr etiza tion schemes f or v olume fr action is summar ized in Spatial D iscretiza tion Schemes f or Volume F raction (p.2099 ). If you ar e mo deling a shar p in terface regime on meshes tha t ha ve high asp ect ratio c ells, large jumps in cell siz e, or high sk ewness , interface captur ing schemes such as Compr essiv e and CICSAM will not pr oduce very shar p results . For such c ases , you should use the Geo-Rec onstr uct scheme . For meshes of go od qualit y, it is r ecommended tha t you use the Compr essiv e scheme , which is available in b oth e xplicit and implicit f ormula tions and is applic able t o both shar p and disp ersed flo w regimes .The Compr essiv e scheme also pr ovides b etter accur acy compar ed with CICSAM and Mod- ified HRIC for most c ases .When used with the implicit f ormula tion and the sec ond or der time scheme , the Compr essiv e scheme pr oduces quit e a shar p in terface. When using the Compr essiv e spa tial discr etiza tion scheme , it is r ecommended tha t you use st ep- wise shar pening af ter the flo w tr ansitions fr om the diffused z one t o the shar pening z one . In other words, you w ould w ant to transition fr om first or der t o sec ond or der, followed b y a tr ansition fr om second or der t o compr essiv e.You w ould w ant to tak e this appr oach if the flo w has a smo oth tr ansition from a shar p in terfacial z one t o a diffused in terfacial z one . However, if the flo w has a nonunif orm transition fr om a diffused in terfacial z one t o a shar p in terfacial z one , this migh t create unph ysical shar pening of the in terface if not handled pr operly, esp ecially f or tr ansien t cases . For e xample , transitioning fr om a slop e limit er of 2 (c ompr essiv e) to a slop e limit er of 0 or 1 (first or der or sec ond order) migh t be acc eptable , but a first or der t o compr essiv e transition migh t create unph ysical shar pening of the in terface. If you ar e solving a pr oblem with the evaporation-c ondensa tion mass tr ansf er mechanism enabled (Including M ass Transf er E ffects (p.2109 )) it is r ecommended tha t you use one of the diffusiv e in terface captur ing schemes such as QUICK ,HRIC , or Phase L ocaliz ed C ompr essiv e (Discretizing U sing the Phase L ocalized C ompr essiv e Scheme (p.2176 )). Imp ortant The BGM scheme pr oduces a shar p in terface, which ma y result in p oor c onvergenc e in some c ases . In such situa tions , we recommend y ou use a lo w value f or the VOF under-r e- 2271Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Solution S trategies f or M ultiphase M odelinglaxa tion. In addition, you c an star t with the Compr essiv e or Modified HRIC scheme and then swit ch t o the BGM scheme . 26.7.5.4. High-O rder R hie-C how F ace Flux Int erp olation In VOF mo deling , using a high-or der discr etiza tion scheme f or the momen tum tr ansp ort equa tions may reduc e the stabilit y of the solution c ompar ed t o cases using first-or der discr etiza tion. In such situa tions , ther e ar e a c ouple of r ecommenda tions: 1.Use a lo w-or der v ariant of the R hie-C how fac e flux in terpolation. This is enabled using the f ollowing text command: solve → set → numerics You will b e ask ed disable high order Rhie-Chow flux? [no] to which y ou will r espond yes . 2.Use a h ybrid tr eatmen t of high-or der R hie-C how fac e flux in terpolation. This is enabled using the following t ext command: solve → set → vof-numerics You will b e ask ed Use hybrid treatment for high order Rhie-Chow flux? [no] to which y ou will r espond yes . Hybrid tr eatmen t allo ws you t o use a high-or der v ariant of the R hie-C how fac e flux in terpol- ation e verywher e inside the domain, except in the vicinit y of the in terface wher e a lo w-or der variant is used f or the in terpolation of the fac e flux. This tr eatmen t could b e helpful t o get better convergenc e without c ompr omising much of the accur acy. 26.7.5.5. Treatment of Unst eady Terms in R hie-C how F ace Flux Int erp olation For c ases using M oving M esh/D ynamic M esh/M ultiple R eference Frame mo dels , ANSY S Fluen t do es not c onsider the unst eady terms f or R hie-C how fac e flux in terpolation b y default. Accoun ting f or the unst eady terms helps t o achie ve better solution stabilit y, esp ecially when using a lo wer time st ep size with the PREST O scheme . To enable f orced tr eatmen t of unst eady terms in R hie-C how fac e flux in terpolation, use the f ollowing text command: solve → set → vof-numerics You will b e ask ed Use forced treatment of unsteady terms in Rhie-Chow flux? [no] to which y ou will r espond yes . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2272Modeling M ultiphase F lows26.7.5.6. Using Unstruc tured Variant of PREST O P ressur e Scheme For he xahedr al and quadr ilateral meshes , ANSY S Fluen t uses the str uctured v ariant of the PREST O scheme b y default. For c ertain c ases with non-c onformal gr id in terfaces, the str uctured v ariant produces une xpected b ehavior a t the in tersec tion of the fluid-fluid and non-c onformal gr id in terfaces. For these cases , using an unstr uctured v ariant of PREST O pr ovides b etter solution stabilit y and a voids une xpec- tedly high v elocities in the vicinit y of the non-c onformal gr id in terfaces. To enable the unstr uctured v ariant of the PREST O scheme , use the f ollowing t ext command: solve → set → vof-numerics You will b e ask ed Use unstructured variant of PRESTO pressure scheme? [no] to which y ou will r espond yes . Note The unstr uctured v ariant of PREST O is aut oma tically enabled f or c ases in volving an unstr uc- tured mesh and this option is r edundan t in its usage . 26.7.5.7. Pressur e-Velocity Coupling and Under -Relaxation for the Time-dep endent Formulations Another change tha t you should mak e to the solv er settings is in the pr essur e-velocity coupling scheme and under-r elaxa tion fac tors tha t you use .The PISO scheme is r ecommended f or tr ansien t calcula tions in gener al. Using PISO allo ws for incr eased v alues on all under-r elaxa tion fac tors, without a loss of solution stabilit y.You c an gener ally incr ease the under-r elaxa tion fac tors f or all v ariables t o 1 and e xpect stabilit y and a r apid r ate of c onvergenc e (in the f orm of f ew it erations r equir ed p er time step). For c alcula tions on t etrahedr al or tr iangular meshes , an under-r elaxa tion fac tor of 0.7–0.8 f or pressur e is r ecommended f or impr oved stabilit y with the PISO scheme . Solution → Controls As with an y ANSY S Fluen t simula tion, the under-r elaxa tion fac tors will need t o be decr eased if the solution e xhibits unstable , divergen t behavior with the under-r elaxa tion fac tors set t o 1. Reducing the time st ep is another w ay to impr ove the stabilit y. 26.7.5.8. Under -Relaxation for the St eady -Stat e Formulation If you ar e using the st eady-sta te implicit VOF scheme , the under-r elaxa tion fac tors f or all v ariables should b e set t o values b etween 0.2 and 0.5 f or impr oved stabilit y. 2273Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Solution S trategies f or M ultiphase M odeling26.7.6. Mixture M odel 26.7.6.1. Setting the Under -Relaxation F actor for the Slip Velocity You should b egin the mix ture calcula tion with a lo w under-r elaxa tion fac tor for the slip v elocity. A value of 0.2 or less is r ecommended . If the solution sho ws go od convergenc e behavior, you c an incr ease this v alue gr adually . 26.7.6.2. Calculating an Initial S olution For some c ases (f or e xample , cyclone separ ation), you ma y be able t o obtain a solution mor e quick ly if you c omput e an initial solution without solving the v olume fr action and slip v elocity equa tions . Onc e you ha ve set up the mix ture mo del, you c an t emp orarily disable these equa tions and c omput e an initial solution. Solution → Controls In the Equa tions D ialog Box (p.3609 ), deselec t Volume F raction and Slip Velocity in the Equa tions list. You c an then c omput e the initial flo w field . Onc e a c onverged flo w field is obtained , turn the Volume F raction and Slip Velocity equa tions back on again, and c omput e the mix ture solution. 26.7.7. Euler ian M odel 26.7.7.1. Calculating an Initial S olution To impr ove convergenc e behavior, you ma y want to comput e an initial solution b efore solving the complet e Euler ian multiphase mo del. There ar e multiple metho ds y ou c an use t o obtain an initial solution f or an E uler ian multiphase c alcula tion: •Set up and solv e the pr oblem using the mix ture mo del (with slip v elocities) inst ead of the E uler ian mo del. You c an then enable the E uler ian mo del, complet e the setup , and c ontinue the c alcula tion using the mixture-mo del solution as a star ting p oint. •Set up the E uler ian multiphase c alcula tion as usual, but c omput e the flo w for only the pr imar y phase .To do this , deselec t Volume F raction in the Equa tions list in the Equa tions D ialog Box (p.3609 ). Onc e you have obtained an initial solution f or the pr imar y phase , turn the v olume fr action equa tions back on and continue the c alcula tion f or all phases . •Use the mass-flo w inlet b oundar y condition t o initializ e the flo w conditions . It is r ecommended tha t you set the v alue of the v olume fr action close t o the v alue of the v olume fr action a t the inlet. •At the b eginning of the solution, a lo wer time st ep is r ecommended in or der t o reach c onvergenc e. •If using the v olume fr action e xplicit scheme , do not star t with a lar ge C ourant numb er at the b eginning of your r un. •If using the v olume fr action e xplicit scheme , star t a r un with a lo wer time st ep and then incr ease the time st ep siz e. Alternatively, this c ould b e done b y using multiphase-sp ecific time st epping , which w ould incr ease the time st ep siz e based on the input par amet ers. •For pr oblems in volving a fr ee sur face or shar p in terfaces b etween the phases , it is r ecommended tha t you use the symmetr ic drag la w, available in the Phase In teraction D ialog Box (p.3451 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2274Modeling M ultiphase F lows•Multiphase-sp ecific time st epping is not r ecommended f or c ompr essible flo ws. Imp ortant You should not try to use a single-phase solution obtained without the mix ture or E uler ian model as a star ting p oint for an E uler ian multiphase c alcula tion. Doing so will not impr ove convergenc e, and ma y mak e it e ven mor e difficult f or the flo w to converge. 26.7.7.2. Temp oraril y Ignoring Lif t and Virtual M ass F orces If you ar e planning t o include the eff ects of lif t and/or vir tual mass f orces in a st eady-sta te Euler ian multiphase simula tion, you c an of ten r educ e stabilit y pr oblems tha t sometimes o ccur in the ear ly stages of the c alcula tion b y temp orarily ignor ing the ac tion of the lif t and the vir tual mass f orces. Onc e the solution without these f orces star ts to converge, you c an in terrupt the c alcula tion, define these f orces appr opriately, and c ontinue the c alcula tion. 26.7.7.3. Using W-Cycle Multigrid For pr oblems in volving a pack ed-b ed gr anular phase with v ery small par ticle siz es (on the or der of 10 m), convergenc e can b e obtained b y using the W-c ycle multigr id for the pr essur e. In the Multigr id tab, under Fixed C ycle P aramet ers in the Advanced S olution C ontrols D ialog Box (p.3611 ), you ma y need t o use higher v alues f or Pre-Sweeps ,Post-S weeps , and Max C ycles .When y ou ar e cho osing the v alues f or these par amet ers, you should also incr ease the Verb osit y to 1 in or der t o monit or the AMG p erformanc e; tha t is, to mak e sur e tha t the pr essur e equa tion is solv ed t o a desir ed le vel of convergenc e within the AMG solv er dur ing each global it eration. See Defining the P hases f or the Euler ian M odel (p.2209 ) for mor e inf ormation ab out gr anular phases , and The V and W C ycles in the Theor y Guide and Modifying A lgebr aic M ultigr id P aramet ers (p.2693 ) for details ab out multigr id cycles . 26.7.7.4. Including the A nisotr opic D rag L aw When using the anisotr opic dr ag la w (Including the M ulti-F luid VOF M odel (p.2249 )), it is r ecommended that you star t the solution with a lo wer anisotr opy ratio. After y our solution has r un f or some time , you c an then incr ease the r atio b y reducing the fr iction fac tor in the tangen tial dir ection. Note tha t You c an also star t the solution with the symmetr ic dr ag la w, then change t o the anisotr opic dr ag la w. Using a smaller under-r elaxa tion f or pr essur e and momen tum ma y also help in c onvergenc e for c ases with a higher anisotr opy ratio. If the flo w for a par ticular phase is imp ortant in b oth dir ections (nor mal and tangen tial t o the in terface), use a lo wer anisotr opy ratio, between 100-1000. A higher anisotr opy ratio migh t cause an unstable solution f or such c ases . For a higher anisotr opy ratio of mor e than 1000, a smaller under-r elaxa tion for pr essur e and momen tum is r ecommended .When using the c oupled multiphase solv er, if the solution is unstable with a higher anisotr opy ratio, then r educing the c ourant numb er ma y be bene- ficial.Anisotropic Drag Method [1], with Viscosity option [2] is r ecommended f or a higher visc osity ratio. 26.7.7.5. Contr olling NIT A Solution O ptions via the Text Int erface For the E uler ian multiphase mo del, the N on-I terative Time A dvancemen t (NIT A) scheme uses PISO as a pr essur e velocity coupling metho d, wher e the pr essur e correction equa tion is solv ed in t wo steps named pr edic tor and c orrector. 2275Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Solution S trategies f or M ultiphase M odelingFor the fac e pr essur e calcula tion, the E uler ian multiphase mo del uses PREST O as a default metho d for b oth the pr edic tor and c orrector st eps. You c an change the fac e pr essur e in terpolation metho d using the f ollowing t ext command: solve/set/multiphase-numerics/nita-controls/face-pressure-options To selec t Body Force Weigh ted as a fac e pr essur e in terpolation metho d for b oth pr edic tor and c or- rector st eps, enter yes at the enable body-force-weighted for face pressure calculation? prompt. To selec t the S econd Or der metho d as a fac e pr essur e in terpolation metho d for b oth pr edic tor and corrector st eps: 1.Enter no at the enable body-force-weighted for face pressure calculation? prompt. 2.When pr ompt ed with face pressure calculation method for predictor step , cho ose Second Or der (1). To selec t the S econd Or der metho d as a fac e pr essur e in terpolation metho d for the c orrector st ep only : 1.Enter no at the enable body-force-weighted for face pressure calculation? prompt. 2.When pr ompt ed with face pressure calculation method for predictor step , retain the default selec tion of PREST O (0). 3.When pr ompt ed with face pressure calculation method for corrector step , cho ose Second Or der (1) . When PRESTO is used f or the fac e pr essur e calcula tion, you will b e ask ed whether y ou w ant to exclude transien t terms. Because the impac t of flux es on the fac e pr essur e is in versely pr oportional t o the time st ep siz e, which ma y lead t o numer ical pr oblems as the time st ep siz e decr eases , the e xclusion of tr ansien t terms is r ecommended f or v ery small time st eps when using PREST O: exclude transient terms in face pressure calculation? [no] yes 26.7.8. Wet S team M odel 26.7.8.1. Boundar y Conditions , Initialization, and P atching When y ou use the w et st eam mo del (descr ibed in Wet S team M odel Theor y in the Theor y Guide , and Setting U p the Wet S team M odel (p.2252 )), the f ollowing t wo field v ariables will sho w up in the inflo w, outflo w b oundar y dialo g boxes, and in the Solution Initializa tion task page and Patch dialo g boxes. •Liquid M ass F raction (or the w etness fac tor) In gener al, for dr y steam en tering flo w b oundar ies the w etness fac tor is z ero. •Log10 (D roplets P er U nit Volume) In gener al this v alue is set t o zero, indic ating z ero dr oplets en tering the domain. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2276Modeling M ultiphase F lows26.7.8.2. Solution Limits for the Wet St eam Mo del When y ou selec t the w et st eam mo del f or the first time , a message is displa yed indic ating tha t the Minimum S tatic Temp erature should b e adjust ed t o 273 K sinc e the accur acy of the built-in st eam data is not guar anteed b elow a v alue of 273 K. If you use y our o wn st eam pr operty func tions , you can adjust this limit t o wha tever is p ermissible f or y our da ta. To adjust the t emp erature limits , go t o the Solution Limits dialo g box. Solution → Controls Limits ... The default maximum w etness fac tor or liquid mass fr action ( ) is set t o 0.1. In gener al, dur ing the convergenc e pr ocess, it is c ommon tha t this limit will b e reached , but e ventually the w etness fac tor will dr op b elow the v alue of 0.1. However, in c ases wher e the limit must b e adjust ed, you c an do so using the t ext user in terface. define → models → multiphase → wet-steam → set → max-liquid-mass-fraction Imp ortant Note tha t the maximum w etness fac tor should not b e set b eyond 0.2 sinc e the pr esen t model assumes a lo w w etness fac tor.When the w etness fac tor is gr eater than 0.1, the solution t ends t o be less stable due t o the lar ge sour ce terms in the tr ansp ort equa tions . Thus, the maximum w etness fac tor has b een set t o a default v alue of 0.1, which c orresponds to the fac t tha t most no zzle and turbine flo ws will ha ve a w etness fac tor less than 0.1. 26.7.8.3. Solution Str ategies for the Wet St eam Mo del If you fac e convergenc e difficulties while solving w et st eam flo w, try to initially lo wer the CFL v alue and use first-or der discr etiza tion schemes f or the solution. If you ar e still unable t o obtain a c onverged solution, then tr y the f ollowing solv er settings: 1.Lower the under-r elaxa tion fac tor for the w et st eam equa tion b elow the cur rent set v alue .The under- relaxa tion fac tor can b e found in the Solution C ontrols task page . Solution → Controls 2.Solve for an initial solution with no c ondensa tion. Onc e you ha ve obtained a pr oper initial solution, turn on the c ondensa tion. To tur n condensa tion on or off , go t o the Solution C ontrols task page . Solution → Controls In the Equa tions dialo g box, deselec t Wet S team in the Equa tions list. When doing so , you ar e preventing c ondensa tion fr om tak ing plac e while still c omputing the flo w based on st eam pr op- erties. Onc e a c onverged flo w field is obtained , turn the Wet S team equa tion back on again and comput e the mix ture solution. 2277Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Solution S trategies f or M ultiphase M odeling26.8. Multiphase C ase C heck You c an check the multiphase c ase setup using the multiphase check func tion a vailable via the t ext user in terface (TUI) c ommand: /report/mphase-summary This func tion pr ints for y ou a summar y of useful settings , imp ortant mo del inf ormation, and r ecommend- ations f or cho osing c ase par amet ers.Your c ase will b e check ed f or c omplianc e in the f ollowing c ategor ies: •MODELING •MESHING •PHASES •PHASE INTERACTION •BOUNDARY CONDITIONS •CELL ZONE CONDITIONS •OPERATING CONDITIONS •SOLVER METHODS/CONTROLS •ADVANCED SOLVER NUMERICS •MULTIPHASE NUMERICS •SOLUTION LIMITS •MONITORS/RESIDUALS •INITIALIZATION •RUN CALCULATION •POST PROCESSING Imp ortant To execut e this c ommand , a case and v alid da ta (solution or initializa tion) ar e requir ed. If the c ase has b een mo dified , you need t o either r einitializ e or r erun the c ase. When pr ompt ed f or verbosity , you c an set the le vel of detail f or the r eport. A v alue of 0 (the default) corresponds t o a basic r eport, while a v alue of 1 corresponds t o a mor e detailed r eport. In each c ategor y, established r ules and built-in b est pr actices will b e available , along with r ecommended changes t o your cur rent settings . At your discr etion, you ma y cho ose t o apply the r ecommenda tions , or k eep y our cur rent settings . Refer to the appr opriate sec tions in the F luen t User's G uide (p.1) for mor e inf ormation ab out the r ecommended changes . For VOF c ases , you c an gener ate a summar y report for the c ase setup using the VOF C heck butt on tha t app ears in the Solution Initializa tion task page af ter y ou initializ e your c ase.The ac tion of this butt on is similar t o the report/mphase-summary text command with the v erbosity set t o 0. 26.9. Postpr ocessing f or M ultiphase M odeling Each of the thr ee gener al multiphase mo dels pr ovides a numb er of additional field func tions tha t you can plot or r eport.You c an also r eport flo w rates for individual phases f or all thr ee mo dels , and displa y velocity vectors f or the individual phases in a mix ture or E uler ian c alcula tion. Information ab out these p ostpr ocessing t opics is pr ovided in the f ollowing subsec tions: 26.9.1. Model-S pecific Variables Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2278Modeling M ultiphase F lows26.9.2. Displa ying Velocity Vectors 26.9.3. Reporting F luxes 26.9.4. Reporting F orces on Walls 26.9.5. Reporting F low Rates 26.9.1. Model-S pecific Variables When y ou use one of the gener al multiphase mo dels , some additional field func tions will b e available for p ostpr ocessing , as list ed in this sec tion. Most field func tions tha t are available in single phase c al- cula tions will b e available f or either the mix ture or each individual phase , as appr opriate for the gen- eral multiphase mo del and sp ecific options tha t you ar e using . See Field F unction D efinitions (p.2959 ) for a c omplet e list of field func tions and their definitions .Displa ying G raphics (p.2775 ) and Reporting Alphanumer ic D ata (p.2909 ) explain ho w to gener ate gr aphics displa ys and r eports of da ta. 26.9.1.1. VOF Mo del For VOF c alcula tions y ou c an gener ate gr aphic al plots or alphanumer ic reports of the f ollowing addi- tional it em: •Volume fr action (in the Phases ... categor y) This it em is a vailable f or each phase . The v ariables tha t are not phase sp ecific ar e available (f or e xample , variables in the Pressur e... and Velocity... categor ies) and r epresen t mix ture quan tities .Thermal quan tities will b e available only f or calcula tions tha t include the ener gy equa tion. 26.9.1.2. Mixture Mo del For c alcula tions with the mix ture mo del, you c an gener ate gr aphic al plots or alphanumer ic reports of the f ollowing additional it ems: •Diamet er (in the Properties ... categor y) This it em is a vailable only f or sec ondar y phases . •Volume fr action (in the Phases ... categor y) This it em is a vailable only f or sec ondar y phases . •Interfacial A rea C onc entration (in the Interfacial A rea C onc entration... categor y) This it em is a vailable only f or sec ondar y phases . The v ariables tha t are not phase sp ecific ar e available (f or e xample , variables in the Pressur e... categor y) represen t mix ture quan tities .Thermal quan tities will b e available only f or c alcula tions tha t include the ener gy equa tion. 26.9.1.3. Eulerian Mo del For E uler ian multiphase c alcula tions y ou c an gener ate gr aphic al plots or alphanumer ic reports of the following additional it ems: 2279Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Postpr ocessing f or M ultiphase M odeling•Diamet er (in the Properties ... categor y) This it em is a vailable only f or sec ondar y phases . •Granular C onduc tivit y (in the Properties ... categor y) This it em is a vailable only f or gr anular phases . •Granular P ressur e (in the Granular P ressur e... categor y) This it em is a vailable only f or gr anular phases . •Granular Temp erature (in the Granular Temp erature... categor y) This it em is a vailable only f or gr anular phases . •Volume fr action (in the Phases ... categor y) This it em is a vailable only f or sec ondar y phases . •Interfacial A rea C onc entration (in the Interfacial A rea C onc entration... categor y) This it em is a vailable only f or sec ondar y phases . The a vailabilit y of turbulenc e quan tities will dep end on which multiphase turbulenc e mo del y ou used in the c alcula tion. Thermal quan tities will b e available (on a p er-phase basis) only f or c alcula tions tha t include the ener gy equa tion. More ad vanced options f or the mix ture phase ar e available under the Phases ... categor y, allo wing you t o selec t from a list of v ariables t o postpr ocess.To acc ess the en tire list in the gr aphic al user in- terface, type the f ollowing t ext command: solve → set → expert Retain most of the default settings , except when ask ed t o Keep temporary solver memory from being freed? . Answ ering yes to this question will e xpose a list under the Phases categor y for the mix ture phase , one of which will b e the Phase ID . Selec ting this option allo ws you t o plot contours of phase IDs f or the v olume fr action, which will facilita te phase distr ibution displa y when mor e than t wo phases ar e pr esen t for fr ee sur face calcula tions . Note The expert option f or not fr eeing t emp orary solv er memor y is inc ompa tible with d ynamic adaption in ser ial and par allel f or all multiphase mo dels . Imp ortant This option is a vailable f or all the multiphase mo dels . However, not e tha t only c ell v alues should b e plott ed f or this option. Make sur e tha t the Node Values option is not selec ted as it will sho w the wr ong phase ID c ontours a t the in terface. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2280Modeling M ultiphase F lows26.9.1.4. Multiphase Sp ecies Transp ort For c alcula tions using sp ecies tr ansp ort with either of the multiphase mo dels , you c an gener ate graphic al plots or alphanumer ic reports of the f ollowing additional it ems: •Mass F raction of sp ecies-n (in the Species ... categor y) This it em is a vailable f or each sp ecies . •Mole F raction of sp ecies-n (in the Species ... categor y) This it em is a vailable f or each sp ecies . •Molar C onc entration of sp ecies-n (in the Species ... categor y) This it em is a vailable f or each sp ecies . •Lam. Diff C oeff of sp ecies-n (in the Species ... categor y) This it em is a vailable f or each sp ecies . •Eff. Diff. Coeff. of sp ecies-n (in the Species ... categor y) This it em is a vailable f or each sp ecies . •Enthalp y of sp ecies-n (in the Species ... categor y) This it em is a vailable f or each sp ecies . •Rela tive Humidit y (in the Species ... categor y). •Turbulen t Rate of Reac tion-n (in the Reac tions ... categor y) This it em is a vailable f or each sp ecies . •Rate of Reac tion (in the Reac tions ... categor y). •Mass Transf er R ate n (in the Phase In teraction... categor y) This it em is a vailable f or each mass tr ansf er mechanism tha t you defined . Thermal quan tities will b e available only f or c alcula tions tha t include the ener gy equa tion. 26.9.1.5. Wet St eam Mo del ANSY S Fluen t provides a wide r ange of p ostpr ocessing inf ormation r elated t o the w et st eam mo del. The w et st eam r elated it ems c an b e found in Wet S team.... categor y of the v ariable selec tion dr op- down list tha t app ears in the p ostpr ocessing dialo g boxes. •Liquid M ass F raction •Liquid M ass G ener ation R ate •Log10 (D roplets P er U nit Volume) 2281Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Postpr ocessing f or M ultiphase M odeling•Log10 (D roplets N uclea tion R ate) •Steam D ensit y (G as-P hase) •Liquid D ensit y (Liquid-P hase) •Mixture Densit y •Saturation R atio •Saturation P ressur e •Saturation Temp erature •Subcooled Vapor Temp erature •Droplet S urface Tension •Droplet C ritical R adius (micr ons) •Droplet A verage R adius (micr ons) •Droplet G rowth R ate (micr ons/s) 26.9.1.6. Dense D iscr ete Phase Mo del For p ostpr ocessing , both the DPM and the E uler ian multiphase c apabilities ar e retained . In addition to usual DPM p ostpr ocessing ( Postpr ocessing f or the D iscrete Phase (p.2027 )), you c an displa y, for e x- ample , vector plots of the par ticle ’s velocity field . Make sur e to selec t the discr ete phase fr om the Phase drop-do wn list. For tr ansien t simula tions tha t include the dense discr ete phase mo del, you can displa y the f ollowing when the Unstead y Statistics ... categor y is selec ted: •Mean Velocity •Mean Volume F raction •Mean P hase D iamet er •RMSE Velocity •RMSE Volume F raction •RMSE P hase D iamet er Imp ortant For the Unstead y Statistics ... categor y to app ear in the p ostpr ocessing dialo g boxes, mak e sure tha t Data S ampling f or Time S tatistics is enabled in the Run C alcula tion task page , and tha t you ha ve performed the c alcula tion. 26.9.2. Displa ying Velocity Vectors For mix ture and E uler ian c alcula tions , it is p ossible t o displa y velocity vectors f or the individual phases using the Vectors dialo g box. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2282Modeling M ultiphase F lowsResults → Graphics → Vectors Edit... To displa y the v elocity of a par ticular phase , selec t Velocity in the Vectors of drop-do wn list , and then selec t the desir ed phase in the Phase drop-do wn list. You c an also cho ose Rela tive Velocity to displa y the phase v elocity relative to a mo ving r eference frame .To displa y the mix ture velocity (relevant for mix ture mo del c alcula tions only), selec t Velocity (or Rela tive Velocity for the mix ture velocity re- lative to a mo ving r eference frame), and mix ture as the Phase . Note tha t you c an c olor v ectors b y values of an y available v ariable , for an y phase y ou defined .To do so , mak e the appr opriate selec tions in the Color b y and f ollowing Phase drop-do wn lists . 26.9.3. Rep orting F luxes When y ou use the Flux Rep orts dialo g box to comput e flux es thr ough b oundar ies, you will b e able to sp ecify whether the r eport is f or the mix ture or f or an individual phase . Results → Rep orts → Fluxes Edit... Selec t mix ture in the Phase drop-do wn list a t the b ottom of the dialo g box to report flux es for the mixture, or selec t the name of a phase t o report flux es just f or tha t phase . When mass tr ansf er is included in multiphase simula tions , ANSY S Fluen t by default uses the f ollowing sensible en thalp y definition f or the r eporting of the en thalpies and t otal hea t transf er rate: wher e is the phase t emp erature for the E uler ian multiphase mo del or the mix ture temp erature for all other multiphase mo dels , is the r eference temp erature, is the f ormation en thalp y at , and is the sp ecific hea t.The v alues f or , , and are those y ou sp ecified in the Create/Edit M aterials dialo g box. The mix ture en thalp y is c alcula ted as a mass-w eigh ted a verage of the phase en thalpies . Note •When the B oiling mo del is used as a mass tr ansf er mechanism, the ANSY S Fluen t postpr ocessing tools ma y report the hea t transf er rate imbalanc e tha t is equal t o boiling hea t flux (in the absenc e of an y external hea t sour ce).This is not an indic ator of an y pr oblem b ecause the r eported im- balanc e is due t o explicit handling of b oiling hea t flux es. •When using the alt ernative formula tion f or mo deling ener gy sour ces due t o mass tr ansf er, you can r efer to Alternative Modeling of Ener gy Sources (p.2111 ) for hea t flux r eporting options and sensible en thalp y definition. 2283Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Postpr ocessing f or M ultiphase M odeling26.9.4. Rep orting F orces on Walls For E uler ian c alcula tions , when y ou use the Force Rep orts dialo g box to comput e forces or momen ts on w all b oundar ies, you will b e able t o sp ecify the individual phase f or which y ou w ant to comput e the f orces. Results → Rep orts → Forces Edit... Selec t the name of the desir ed phase in the Phase drop-do wn list on the lef t side of the dialo g box. 26.9.5. Rep orting F low R ates You c an obtain a r eport of mass flo w rate for each phase (and the mix ture) thr ough each flo w boundar y using the report/fluxes/mass-flow text command: report → fluxes → mass-flow When y ou sp ecify the phase of in terest (the mix ture or an individual phase), ANSY S Fluen t will giv e you the option t o list each z one , followed b y a summar y of the mass flo w rate thr ough tha t zone f or the sp ecified phase , or will summar ize the mass flo w rate for all z ones . An example is sho wn b elow, demonstr ating ho w to list the mass flo w rate for all z ones . /report/fluxes> mf (mixture water air) domain id/name [mixture] air all boundary/interior zones [yes] Write to File? [no] air Mass Flow Rate (kg/s) -------------------------------- -------------------- spiral-press-outlet -1.2330244 pressure-outlet -9.7560663 spiral-vel-inlet 0.6150589 walls 0 velocity-inlet 4.9132133 ---------------- -------------------- Net -5.4608185 Note The mass flo w rate is c alcula ted thr ough the simula tion domain or the sp ecified z ones . However, if y ou sp ecify only the in terior z one(s), the net mass flo w rate ma y sho w as 0, because these in ternal b oundar ies ar e sk ipped when ANSY S Fluen t comput es the net influx and outflux. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2284Modeling M ultiphase F lowsChapt er 27: Popula tion B alanc e M odel This chapt er pr ovides basic instr uctions t o install the p opula tion balanc e mo del and solv e popula tion balanc e pr oblems in ANSY S Fluen t. It assumes tha t you ar e alr eady familiar with standar d ANSY S Fluen t features, including the user-defined func tion pr ocedur es descr ibed in the Fluen t Customiza tion M anual . This chapt er descr ibes the f ollowing: 27.1. Popula tion B alanc e Module Installa tion 27.2. Loading the P opula tion B alanc e Module 27.3. Popula tion B alanc e Model S etup 27.4. Postpr ocessing f or the P opula tion B alanc e Model 27.5. UDFs f or P opula tion B alanc e Modeling 27.6. DEFINE_HET_R XN_R ATE M acro 27.1. Popula tion B alanc e M odule Installa tion The p opula tion balanc e mo dule is pr ovided as an add-on mo dule with the standar d ANSY S Fluen t licensed software. 27.2. Loading the P opula tion B alanc e M odule The p opula tion balanc e mo dule is loaded in to ANSY S Fluen t thr ough the t ext user in terface (TUI). The module c an only b e loaded when a v alid ANSY S Fluen t case file has b een set or r ead.The t ext command to load the mo dule is: define → models → addon-module A list of ANSY S Fluen t add-on mo dules is displa yed: > /define/models/addon-module Fluent Addon Modules: 0. None 1. MHD Model 2. Fiber Model 3. Fuel Cell and Electrolysis Model 4. SOFC Model with Unresolved Electrolyte 5. Population Balance Model 6. Adjoint Solver 7. Single-Potential Battery Model 8. Dual-Potential MSMD Battery Model 9. PEM Fuel Cell Model Enter Module Number: [0] 5 Selec t the Population Balance Model by en tering the mo dule numb er 5. During the loading process a Scheme libr ary containing the gr aphic al and t ext user in terface, and a UDF libr ary containing a set of user defined func tions ar e loaded in to ANSY S Fluen t. A message Addon M odule: pop- bal...loaded! is displa yed a t the end of the loading pr ocess. The p opula tion balanc e mo dule setup is sa ved with the ANSY S Fluen t case file .The mo dule is loaded automa tically when the c ase file is subsequen tly r ead in to ANSY S Fluen t. Note tha t in the sa ved c ase 2285Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.file, the p opula tion balanc e mo dule is sa ved with the absolut e pa th.Therefore, if the lo cations of the popula tion balanc e mo dule installa tion or the sa ved c ase file ar e changed , ANSY S Fluen t will not b e able t o load the mo dule when the c ase file is subsequen tly r ead. 27.3. Popula tion B alanc e M odel S etup Following the loading of the p opula tion balanc e mo dule , enable either the mix ture or E uler ian multiphase model. This will enable y ou t o ac tivate the p opula tion balanc e mo del, wher e you will sp ecify the appr o- priate par amet ers, and supply multiphase b oundar y conditions .These inputs ar e descr ibed in this sec tion. Using the double-pr ecision v ersion of ANSY S Fluen t when solving p opula tion balanc e pr oblems is highly recommended . Imp ortant A limita tion of the p opula tion balanc e mo del is tha t it c an b e used only on one sec ondar y phase , even if y our pr oblem includes additional sec ondar y phases . Note tha t a thr ee-phase gas-liquid-solid c ase c an b e mo deled , wher e the p opula tion balanc e mo del is used f or the gas phase and the solid phase ac ts as a c atalyst. However, if y ou ar e using the Inhomo gen- eous D iscr ete, mor e than one sec ondar y phase c an b e used . Note tha t the pr operties of the secondar y phases selec ted f or tha t metho d should b e the same f or c onsist ency. For mor e inf ormation, see the f ollowing sec tions: 27.3.1. Enabling the P opula tion B alanc e Model 27.3.2. Defining P opula tion B alanc e Boundar y Conditions 27.3.3. Specifying P opula tion B alanc e Solution C ontrols 27.3.4. Coupling With F luid D ynamics 27.3.5. Specifying In terphase M ass Transf er D ue to Nuclea tion and G rowth 27.3.1. Enabling the P opula tion B alanc e M odel The pr ocedur e for setting up a p opula tion balanc e pr oblem is descr ibed b elow. (Note tha t this pr ocedur e includes only those st eps nec essar y for the p opula tion balanc e mo del itself ; you will need t o set up other mo dels , boundar y conditions , and so on, as usual. See the ANSY S Fluen t User's G uide (p.1) for details .) 1.Start the double-pr ecision v ersion of ANSY S Fluen t. 2.To enable the p opula tion balanc e mo del, follow the instr uctions in Loading the P opula tion B alanc e Module (p.2285 ). Rememb er to enable the mix ture or E uler ian multiphase mo del. 3.Open the Popula tion B alanc e M odel dialo g box (Figur e 27.1: The P opula tion B alanc e Model D ialog Box (p.2287 )). Setup → Models → Popula tion B alanc e Edit... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2286Popula tion B alanc e ModelFigur e 27.1: The P opula tion B alanc e M odel D ialo g Box 4.Specify the p opula tion balanc e metho d under Metho d. •If you selec t Discr ete, you will need t o sp ecify the f ollowing par amet ers: 2287Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Popula tion B alanc e Model S etupKv specifies the v alue f or the par ticle v olume c oefficien t (as descr ibed in Particle G rowth ). By default , this c oefficien t has a v alue of . Definition can b e sp ecified as a Geometr ic R atio or as a File. If Geometr ic R atio is selec ted, then the Ratio Exponen t must b e sp ecified . If File is selec ted, you will click the Load F ile... butt on and selec t the bin siz e file tha t you w ant loaded . You c an input the diamet er thr ough the t ext file , with each diamet er list ed on a separ ate line, star ting fr om the smallest t o the lar gest diamet er (one en try per line). Hence, you ar e not limit ed b y the choic es sp ecified in the dialo g box. Bins specifies the numb er of par ticle siz e bins used in the c alcula tion. Ratio E xponen t specifies the e xponen t used in the discr etiza tion of the gr owth t erm volume c oordina te (see Nu- mer ical M etho d). Min D iamet er specifies the minimum bin siz e . Max D iamet er displa ys the maximum bin siz e, which is c alcula ted in ternally . To displa y a list of the bin siz es in the c onsole windo w, click Print Bins .The bin siz es will b e listed in or der of siz e, from the lar gest t o the smallest. This option is only a vailable when the Geometr ic R atio D efinition is selec ted. •If you selec t Inhomo geneous D iscr ete under Metho d, you will sp ecify the same par amet ers as f or the Discr ete mo del. Additionally , you c an include mor e than one sec ondar y phase in the bin definition. Enter the t otal numb er of Active Secondar y Phases in y our simula tion. Note While r eading bins thr ough the Load F ile... option f or the Inhomo geneous D iscr ete model, the c orresponding phase name must b e included , for e xample (("air-1" (0.1 0.2 0.3)) •If you selec t Standar d M omen t under Metho d, you will sp ecify the numb er of Momen ts under Para- met ers. •If you selec ted Quadr ature M omen t under Metho d, you will set the numb er of momen ts to either 4, 6 or 8 under Paramet ers. •If you selec ted DQMOM under Metho d, you will selec t the DQMOM P hases from the list. You will also specify the f ollowing Paramet ers: Max S ize specifies the maximum siz e of the par ticle . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2288Popula tion B alanc e ModelMin S ize specifies the minimum siz e of the par ticle . Referenc e Length is the r eference par ticle siz e. Normally , the a veraged siz e of the par ticle gr oup should b e sufficien t. Min VOF is the minimum VOF, wher e the t otal v olume fr action of the par ticle phases (par ticipa ting in DQMOM computa tions) is b elow the minimum v alue; the sour ce terms c aused b y the br eakage and c oales- cence are not c omput ed in tha t cell for the DQMOM and VOF equa tions . Max VOF C hange/T ime S tep is the maximum VOF change in p ercentage f or each DQMOM phase p er time st ep, in or der t o smo oth the c onvergenc e pr ogress. Gener ate DQMOM Values enables y ou t o gener ate DQMOM v alues fr om PDF , CDF , or O verall M omen ts files . Each of the file formats and the w ay to gener ate the v alues ar e discussed in Gener ated DQMOM Values (p.2295 ). Note The DQMOM metho d is r estricted t o a f our-phase sy stem, of which thr ee sec ondar y phases ar e dir ectly in volved in the DQMOM c omputa tion. Unsteady simula tions ar e requir ed t o mo del br eakage and c oalesc ence and a w ell defined initial field is r ecom- mended , in which the abscissas ar e distinc t. Only gr owth, breakage, and aggr egation are the a vailable phenomena. No nuclea tion is c onsider ed. 5.Selec t the sec ondar y phase fr om the Phase drop-do wn list f or which y ou w ant to apply the p opula tion balanc e mo del par amet ers. 6.For all p opula tion balanc e metho ds, you c an enable the f ollowing under Phenomena : Nuclea tion R ate enables y ou t o sp ecify the nuclea tion r ate ( ).You c an selec t constan t or user-defined from the dr op-do wn list. If you selec t constan t, specify a v alue in the adjac ent field . If you ha ve a user- defined func tion (UDF) tha t you w ant to use t o mo del the nuclea tion r ate, you c an cho ose the user- defined option and sp ecify the appr opriate UDF . Note This option is not a vailable when using the Inhomo geneous D iscr ete metho d. Growth R ate enables y ou t o sp ecify the par ticle gr owth r ate (m/s). You c an selec t constan t or user-defined from the dr op-do wn list. If you selec t constan t, specify a v alue in the adjac ent field . If you ha ve a user- 2289Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Popula tion B alanc e Model S etupdefined func tion (UDF) tha t you w ant to use t o mo del the gr owth r ate, you c an cho ose the user- defined option and sp ecify the appr opriate UDF . Note This option is not a vailable when using the Inhomo geneous D iscr ete metho d. Aggr ega tion K ernel enables y ou t o sp ecify the aggr egation k ernel ( ) and sp ecify the Aggr ega tion F actor. The Aggr ega tion F actor ( in Equa tion 19.38 in the Fluent Theor y Guide ) is used f or the c alib- ration of the aggr egation k ernel. For Rate, you c an selec t constan t,luo-mo del,free-molecular-mo del,turbulen t-mo del,prince- blanch-mo del, or user-defined from the dr op-do wn list: •If you selec t constan t, specify a v alue in the adjac ent field . •If you selec t luo-mo del, the Surface Tension f or P opula tion B alanc e dialo g box will op en aut o- matically t o enable y ou t o sp ecify the sur face tension (see Figur e 27.2: The Sur face Tension f or Popula tion B alanc e Dialog Box (p.2290 )).The aggr egation r ate for the mo del will then b e calcula ted based on L uo’s aggr egation k ernel (as descr ibed in Particle B irth and D eath D ue t o Breakage and Aggregation ). Figur e 27.2: The S urface Tension f or P opula tion B alanc e D ialo g Box •If you selec t free-molecular-mo del, then Equa tion 19.47 is applied . •If you selec t turbulen t-mo del, the Hamak er C onstan t for P opula tion B alanc e dialo g box will open aut oma tically t o enable y ou t o sp ecify the Hamak er constan t (see Figur e 27.3: The Hamak er Constan t for P opula tion B alanc e Dialog Box (p.2291 )). More inf ormation ab out this mo del is a vailable in Turbulen t Aggregation Ker nel. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2290Popula tion B alanc e ModelFigur e 27.3: The H amak er C onstan t for P opula tion B alanc e D ialo g Box •If you selec t prince-blanch-mo del, the Prince and Blanch M odel P aramet ers dialo g box will op en automa tically. Note tha t because this is a mo dal dialo g box, you must t end t o it immedia tely. Figur e 27.4: The Prince and Blanch M odel P aramet ers Dialo g Box You c an sp ecify the f ollowing par amet ers: –Surface Tension –Initial F ilm Thick ness : Is in Equa tion 19.57 in the Fluent Theor y Guide . –Final F ilm Thick ness : Is in Equa tion 19.57 in the Fluent Theor y Guide . –Buo yanc y Coalesc enc e Coefficien t: Is in Equa tion 19.63 in the Fluent Theor y Guide . –Turbulenc e Coalesc enc e Coefficien t: Is in Equa tion 19.60 in the Fluent Theor y Guide . More inf ormation ab out this mo del is a vailable in Prince and B lanch A ggregation Ker nel. •If you ha ve a user-defined func tion (UDF) tha t you w ant to use t o mo del the aggr egation r ate, you can cho ose the user-defined option and sp ecify the appr opriate UDF . 2291Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Popula tion B alanc e Model S etupBreak age K ernel enables y ou t o sp ecify the par ticle br eakage fr equenc y ( ) and the Break age F actor. The Break age F actor ( in Equa tion 19.16 in the Fluent Theor y Guide ) is used f or the c alibr ation of the br eakage k ernel. For Frequenc y, you c an selec t constan t,luo-mo del,lehr-mo del,ghadir i-mo del,laakk onen- model or user-defined from the Frequenc y drop-do wn list: •If you selec t constan t, specify a v alue in the adjac ent field . •If you selec t luo-mo del, the Surface Tension f or P opula tion B alanc e dialo g box will op en aut o- matically t o enable y ou t o sp ecify the sur face tension (see Figur e 27.2: The Sur face Tension f or Popula tion B alanc e Dialog Box (p.2290 )).The fr equenc y used in the br eakage r ate will then b e calcu- lated based on L uo’s breakage k ernel (as descr ibed in Particle B irth and D eath D ue t o Breakage and Aggregation ). •If you selec t lehr-mo del, the Surface Tension and Weber N umb er dialo g box will op en aut oma t- ically t o enable y ou t o sp ecify the sur face tension and cr itical Weber numb er (see Figur e 27.5: The Surface Tension and Weber N umb er D ialog Box (p.2292 )).The fr equenc y used in the br eakage r ate will then b e calcula ted based on L ehr’s breakage k ernel (as descr ibed in Particle B irth and D eath Due t o Breakage and A ggregation ). Figur e 27.5: The S urface Tension and Weber N umb er D ialo g Box •If you selec t ghadir i-mo del, the Ghadir i Break age C onstan t for P opula tion B alanc e dialo g box will op en aut oma tically t o enable y ou t o sp ecify the br eakage c onstan t (see Figur e 27.6: The G hadir i Breakage C onstan t for P opula tion B alanc e Dialog Box (p.2293 )).The fr equenc y will then b e calcula ted based on G hadir i’s breakage k ernel (as descr ibed in Particle B irth and D eath D ue t o Breakage and Aggregation ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2292Popula tion B alanc e ModelFigur e 27.6: The G hadir i Br eak age C onstan t for P opula tion B alanc e D ialo g Box •If you selec t laakk onen-mo del, the Surface Tension f or P opula tion B alanc e dialo g box will op en automa tically t o enable y ou t o sp ecify the Surface Tension and the c onstan t C2 (Laakk onen Breakage Ker nels ).The fr equenc y will then b e calcula ted based on Laakk onen's br eakage k ernel (as descr ibed in Laakk onen B reakage Ker nels ). •If you ha ve a user-defined func tion (UDF) tha t you w ant to use t o mo del the fr equenc y for the breakage r ate, you c an cho ose the user-defined option and sp ecify the appr opriate UDF . If you selec ted constan t,ghadir i-mo del,laakk onen-mo del, or user-defined for Frequenc y, then y ou c an sp ecify the pr obabilit y densit y func tion used t o calcula te the br eakage r ate by mak ing a selec tion in the PDF drop-do wn list. You c an selec t parabolic ,laakk onen ,gener aliz ed, or user-defined : •If you selec t parabolic , the Shap e Factor f or P arabolic PDF dialo g box will op en aut oma tically t o enable y ou t o sp ecify the shap e fac tor C (see Figur e 27.7: The S hap e Factor for P arabolic PDF D ialog Box (p.2293 )).The PDF used in the br eakage r ate will then b e calcula ted acc ording t o Equa tion 19.28 (as descr ibed in Particle B irth and D eath D ue t o Breakage and A ggregation ). Figur e 27.7: The S hap e Factor f or P arabolic PDF D ialo g Box •If you selec t gener aliz ed, the Gener aliz ed p df for multiple br eak age dialo g box will op en aut o- matically ( Figur e 27.8: The G ener alized p df for multiple br eakage D ialog Box (p.2294 )). 2293Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Popula tion B alanc e Model S etupFigur e 27.8: The G ener aliz ed p df f or multiple br eak age D ialo g Box Perform the f ollowing st eps in the Gener aliz ed p df f or multiple br eak age dialo g box: a.Selec t either One Term or Two Term from the Options list. Your selec tion will det ermine whether in Equa tion 19.34 is 0 or 1, respectively. b.Enter a v alue f or the a veraged Numb er of D augh ters. It can b e an y real numb er (including non-in tegers , such as 2.5), as long as it is not less than 2. c.Define the par amet er(s) f or Equa tion 19.34 in the Input P aramet ers group b ox.When One Term is selec ted fr om the Options list, you must en ter a v alue f or qi0.When Two Term is selec ted from the Options list, you must en ter values f or wi0 ,pi0,qi0,ri0, and qi1. For inf ormation about appr opriate values f or these par amet ers t o result in the daugh ter distr ibutions sho wn in Table 19.3: Daugh ter D istributions , see Table 19.4: Daugh ter D istributions (c ont.). Note For the equal-siz e gener alized p df br eakage distr ibution, the v alue f or qi0 should b e set t o 1e20 . d.Click the Valida te/A pply butt on t o sa ve the settings .The t ext boxes in the All Paramet ers group b ox will b e up dated, using the v alues y ou en tered in the Input P aramet ers group b ox, as w ell as v alues der ived fr om the c onstr aints sho wn in Equa tion 19.35 – Equa tion 19.37 . e.Verify tha t the v alues in the All Paramet ers group b ox represen t your in tended PDF b efore click ing Close . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2294Popula tion B alanc e Model•If you ha ve a user-defined func tion (UDF) tha t you w ant to use t o mo del the PDF f or the br eakage rate, you c an cho ose the user-defined option and sp ecify the appr opriate UDF . See UDFs f or P op- ulation B alanc e Modeling (p.2310 ) for details ab out UDFs f or the p opula tion balanc e mo del. Choose b etween the default Hagesa ther formula tion and the Ramak rishna formula tion. Detailed information ab out these t wo metho ds c an b e found in Breakage F ormula tions f or the D iscrete Metho d. 7.(Discrete and QMOM mo dels only) I f you w ant to acc oun t for bubble e xpansion due t o lar ge changes in hydrosta tic pr essur e in c ompr essible flo ws, enable Include E xpansion .The bubble e xpansion is mo deled as a gr owth t erm in the P opula tion B alanc e equa tions ( Equa tion 19.9 ).This c an b e relevant in applic ations such as deep-w ater dr illing . For mor e inf ormation, see Particle G rowth . Note The sec ondar y phase must b e mo deled as c ompr essible .This option is cur rently a vailable for D iscrete and QMOM only . 8.Specify the b oundar y conditions f or the solution v ariables . Setup → Boundar y Conditions See Defining P opula tion B alanc e Boundar y Conditions (p.2299 ) below. 9.Specify the initial guess f or the solution v ariables . Solution → Initializa tion 10.Solve the pr oblem and p erform relevant postpr ocessing func tions . Solution → Run C alcula tion See Postpr ocessing f or the P opula tion B alanc e M odel (p.2307 ) for details ab out p ostpr ocessing . 27.3.1.1. Gener ated DQMOM Values When using the DQMOM mo del, you ha ve the option of gener ating DQMOM v alues fr om thr ee dif- ferent file f ormats.To do so , selec t Overall M omen ts,PDF or CDF under Gener ate DQMOM Values and then click the Load F ile… butt on.The Selec t File dialo g box will op en wher e you will selec t the appr opriate file . Clicking OK in the Selec t File dialo g box will r esult in the file b eing r ead and c alcu- lations c arried out. The DQMOM v alues will b e pr inted in the c onsole . 2295Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Popula tion B alanc e Model S etupFigur e 27.9: The P opula tion B alanc e M odel D ialo g Box for the DQMOM M odel DQMOM Values P roduc ed F rom PDF , CDF F iles , or O verall M omen ts for the P articles •Three quadr ature points ar e assumed , namely QP0, QP1, and QP2 (see Figur e 27.10: DQMOM Values Produced F rom a PDF F ile (p.2297 )). •Length ,Volume Fraction , and DQMOM-m4 values ar e giv en.The la tter two can b e used f or initial fields of VOF and DQMOM as w ell as b oundar y conditions . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2296Popula tion B alanc e Model•For v erification pur poses , the first six momen ts ar e also giv en t ogether with the t otal v olume fr action of all par ticles fr om the PDF or CDF file . It is y our r esponsibilit y to mak e sur e tha t these v alues ar e correct, esp ecially the t otal v olume fr action. •The definition of the first six momen ts of the par ticles is length based f or the o verall momen ts, de- scribed in The Q uadr ature Metho d of M omen ts (QMOM) . •In PDF or CDF f ormat, the r esultan t volume fr action is nor mally giv en as unit y. If you w ant the r eal particle v olume fr action t o be reflec ted in the mix ture, the sec ond c olumn of the PDF or CDF da ta file need t o be multiplied b y the v alue of the r eal v olume fr action. Another w ay is t o multiply the values of the gener ated DQMOM v olume fr action and DQMOM-m4 using the r eal par ticle v olume fraction. Figur e 27.10: DQMOM Values P roduc ed F rom a PDF F ile PDF F ile F ormat •The pr obabilit y densit y func tion (PDF) is defined b y the pr obabilit y distr ibution of par ticles in t erms of the v olume fr action o ver the par ticle length (namely the diamet er of the par ticle). •The in tegration of PDF o ver all p ossible par ticle length (nor mally fr om 0 t o the maximum diamet er) shall giv e a v alue of unit y or the r eal v alue of the v olume fr action of all par ticipa ting par ticles . •The following file f ormat is r equir ed (as sho wn b elow): –An in teger numb er sp ecified in the first line , indic ating the numb er of da ta pairs t o follow –The da ta in the 1st c olumn sp ecifying the length or diamet er of par ticles in asc ending or der in met ers (m) –The da ta in the 2nd c olumn sp ecifying the pr obabilit y densit y func tion. Be aware tha t the in tegration of the PDF o ver the length shall r esult in a v alue of v olume fr action f or tha t par ticular par ticle length r ange 37 5e-6 0.000058e6 10e-6 0.000271e6 15e-6 0.000669e6 20e-6 0.001264e6 25e-6 0.002062e6 30e-6 0.003055e6 35e-6 0.004228e6 40e-6 0.005549e6 2297Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Popula tion B alanc e Model S etup45e-6 0.006972e6 50e-6 0.008439e6 55e-6 0.00988e6 60e-6 0.011217e6 65e-6 0.012366e6 70e-6 0.013253e6 75e-6 0.013811e6 80e-6 0.013996e6 85e-6 0.013789e6 90e-6 0.013199e6 95e-6 0.012268e6 100e-6 0.011062e6 105e-6 0.009668e6 110e-6 0.00818e6 115e-6 0.006694e6 120e-6 0.00529e6 125e-6 0.004033e6 130e-6 0.002962e6 135e-6 0.002093e6 140e-6 0.00142e6 145e-6 0.000925e6 150e-6 0.000576e6 155e-6 0.000344e6 160e-6 0.000196e6 170e-6 0.000055e6 180e-6 0.000012e6 190e-6 0.000002e6 200e-6 0. 210e-6 0. CDF F ile F ormat •The cumula tive densit y func tion (CDF) is defined as the in tegration of PDF o ver all p ossible par ticles up t o the length , resulting in a v alue of v olume fr action f or all par ticles less than length . •The v alue of the CDF a t the maximum par ticle length/diamet er shall b e unit y, or the r eal v alue of the volume fr action of all par ticles in the mix ture. •The following file f ormat is r equir ed (as sho wn b elow): –An in teger numb er sp ecified in the first line , indic ating the numb er of da ta pairs t o follow –The da ta in the 1st c olumn sp ecifying the length or diamet er of par ticles in asc ending or der in met ers (m) –The da ta in the 2nd c olumn sp ecifying the cumula tive densit y func tion in t erms of the v olume fraction of par ticles – at the maximum par ticle length 37 5e-6 0 10e-6 0.109e-2 15e-6 0.16e-2 20e-6 0.175e-2 25e-6 0.208e-2 30e-6 0.304e-2 35e-6 0.614e-2 40e-6 1.5e-2 44e-6 3.e-2 45e-6 3.44e-2 50e-6 6.573e-2 55e-6 11.19e-2 60e-6 17.11e-2 65e-6 24.17e-2 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2298Popula tion B alanc e Model70e-6 32.007e-2 75e-6 40.243e-2 80e-6 48.397e-2 85e-6 56.453e-2 90e-6 63.823e-2 95e-6 70.53e-2 100e-6 76.073e-2 105e-6 81e-2 110e-6 85.057e-2 115e-6 88.187e-2 120e-6 90.89e-2 125e-6 92.897e-2 130e-6 94.437e-2 135e-6 95.543e-2 140e-6 96.523e-2 145e-6 97.173e-2 150e-6 97.717e-2 155e-6 98.007e-2 160e-6 98.363e-2 170e-6 98.88e-2 180e-6 99.16e-2 190e-6 99.327e-2 200e-6 100.e-2 Overall M omen ts F ile F ormat •The thir d option is t o sp ecify the first six momen ts for all par ticles as sho wn b elow. •The following file f ormat is r equir ed (as sho wn b elow): –An in teger numb er sp ecified in the first line , indic ating the numb er of da ta (momen ts) t o follow. By default , this shall b e 6 –six momen ts fr om momen t-0 t o momen t-5 ar e giv en in tha t order.The definition of the first six momen ts is based on length as descr ibed in The Q uadr ature Metho d of M omen ts (QMOM) –As a check f or momen ts, . In the v alues giv en b elow, volume fraction is assumed t o be unit y and is assumed t o be 6 1.120556e+013 4.022475e+008 2.523370e+004 1.909857e+000 1.611191e-004 1.498663e-008 27.3.2. Defining P opula tion B alanc e Boundar y Conditions To define b oundar y conditions sp ecific t o the p opula tion balanc e mo del, use the f ollowing pr ocedur e: 1.In the Boundar y Conditions task page , selec t the sec ondar y phase(s) in the Phase drop-do wn list and then op en the appr opriate boundar y condition dialo g box (for e xample ,Figur e 27.11: Specifying Inlet Boundar y Conditions f or the P opula tion B alanc e Model (p.2300 )). Setup → Boundar y Conditions 2299Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Popula tion B alanc e Model S etupFigur e 27.11: Specifying Inlet B oundar y Conditions f or the P opula tion B alanc e M odel 2.In the Multiphase tab , under Boundar y Condition , selec t the t ype of b oundar y condition f or each bin (for the discr ete metho d) or momen t (for SMM and QMOM) as either Specified Value or Specified F lux. Note tha t the b oundar y condition v ariables (f or e xample ,Bin-0 ) are lab eled acc ording t o the f ol- lowing: bin/moment - th bin/momen t wher e the th bin/moment can r ange fr om 0 (the first bin or momen t) to , wher e is the numb er of bins/momen ts tha t you en tered in the Popula tion B alanc e M odel dialo g box. 3.Under Popula tion B alanc e Boundar y Value , enter a v alue or a flux as appr opriate. •If you selec ted Specified Value for the selec ted b oundar y variable , enter a v alue in the field adjac ent to the v ariable name .This v alue will c orrespond t o the v ariable in Equa tion 19.68 (for the discr ete metho d) or in Equa tion 19.83 (for SMM or QMOM). If you ar e using either of the discr ete metho ds and ha ve selec ted Specified Value for all bins , you c an optionally sp ecify a lo g-nor mal distr ibution and have Fluen t aut oma tically initializ e the bin fr actions acc ordingly t o a lo g-nor mal distr ibution (see Initial- izing B in Fractions With a L og-Normal D istribution (p.2301 )). •If you selec ted Specified F lux for the selec ted b oundar y variable , enter a v alue in the field adjac ent to the v ariable name .This v alue will b e the spa tial par ticle v olume flux . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2300Popula tion B alanc e Model27.3.2.1. Initializing B in F ractions With a L og-N ormal D istribution When using one of the discr ete metho ds with S pecified Value selec ted as the b oundar y condition for all bins , you c an ha ve Fluen t popula te the bin fr actions acc ording t o a lo g-nor mal distr ibution char acterized b y a mean and standar d de viation tha t you supply . For details of the lo g-nor mal distr i- bution, refer to The L og-Normal D istribution . Imp ortant The lo g-nor mal initializa tion f eature is only meaning ful and should only b e used when Specified Value is selec ted f or all bins under Boundar y Condition . To use the lo g-nor mal distr ibution, perform the f ollowing st eps. 1. Enable Log Normal in the Boundar y Value group b ox. 2. Enter values f or the Mean and Std D ev of the desir ed distr ibution. 3. Click Initializ e... 2301Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Popula tion B alanc e Model S etup27.3.3. Specifying P opula tion B alanc e Solution C ontrols In the Equa tions dialo g box (Figur e 27.12: The E qua tions D ialog Box (p.2302 )), equa tions f or each bin (for e xample ,phase-2 Bin ) will app ear in the Equa tions list. Solution → Controls Equa tions ... The default v alue under Under-Relaxa tion F actors (in the Solution C ontrols task page) f or the p op- ulation balanc e equa tions is 0.5 , and the default Discr etiza tion scheme (in the Solution M etho ds task page) is First Or der U pwind . Figur e 27.12: The E qua tions D ialo g Box 27.3.4. Coupling With F luid D ynamics To couple p opula tion balanc e mo deling of the sec ondar y phase(s) with the o verall pr oblem fluid d y- namics , a Sauter mean diamet er ( in Equa tion 19.90 ) ma y be used t o represen t the par ticle diamet er of the sec ondar y phase .The S auter mean diamet er is defined as the r atio of the thir d momen t to the second momen t for the SMM and QMOM. For the discr ete metho d, it is defined as (27.1) To sp ecify the S auter mean diamet er as the sec ondar y phase par ticle diamet er, open the Secondar y Phase dialo g box. Setup → Models → Multiphase → Phases → phase–id – S econdar y Phase Edit... In the Secondar y Phase dialo g box (for e xample ,Figur e 27.13: The S econdar y Phase D ialog box for Hydrodynamic C oupling (p.2303 )), selec t saut er-mean from the Diamet er drop-do wn list under Prop- erties . Note tha t a c onstan t diamet er or user-defined func tion ma y also b e used . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2302Popula tion B alanc e ModelFigur e 27.13: The S econdar y Phase D ialo g box for H ydrodynamic C oupling 27.3.5. Specifying In terphase M ass Transf er D ue t o Nuclea tion and G rowth In applic ations tha t involve the cr eation, dissolution, or gr owth of par ticles (such as cr ystalliza tion), the t otal v olume fr action equa tion f or the par ticula te phase will ha ve sour ce terms due t o these phe- nomena. The momen tum equa tion f or the par ticula te phase will also ha ve sour ce terms due t o the added mass . In ANSY S Fluen t, the mass sour ce term can b e sp ecified using the UDF ho ok DEFINE_HET_RXN_RATE , as descr ibed in DEFINE_HET_RXN_RATE Macro (p.2317 ), or using the Phase In teraction dialo g box, descr ibed b elow. As an e xample , in cr ystalliza tion, par ticles ar e created b y means of nuclea tion ( ), and a gr owth r ate ( ) can also b e sp ecified .The mass tr ansf er rate of f ormation (in ) of par ticles of all siz es is then (27.2) For the discr ete metho d, the mass tr ansf er rate due t o gr owth c an b e wr itten as 2303Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Popula tion B alanc e Model S etup(27.3) If the nuclea tion r ate is included in the t otal mass tr ansf er, then the mass tr ansf er b ecomes (27.4) Imp ortant For the discr ete metho d, the sour ces to the p opula tion balanc e equa tions must sum t o the total mass tr ansf er rate.To acc ess the sour ces, you c an use the macr o C_PB_DISCI_PS (cell, thread, i) . See UDFs f or P opula tion B alanc e M odeling (p.2310 ) for mor e inf ormation ab out macr os for p opula tion balanc e variables . For the SMM, only a siz e-indep enden t growth r ate is a vailable . Hence, the mass tr ansf er rate can b e written as (27.5) For the QMOM, the mass tr ansf er rate can b e wr itten as (27.6) For b oth the SMM and QMOM, mass tr ansf er due t o nuclea tion is negligible , and is not tak en in to ac- coun t. Imp ortant Note tha t for cr ystalliza tion, the pr imar y phase has multiple c omp onen ts; at the v ery least , ther e is a solut e and a solv ent.To define the multic omp onen t multiphase sy stem, you will need t o ac tivate Species Transp ort in the Species M odel dialo g box for the pr imar y phase after ac tivating the multiphase mo del. The r est of the pr ocedur e for setting up a sp ecies transp ort problem is iden tical to setting up sp ecies in single phase .The het erogeneous r e- action is defined as: When the p opula tion balanc e mo del is ac tivated, mass tr ansf er b etween phases f or non-r eacting sp ecies (such as b oiling) and het erogeneous r eactions (such as cr ystalliza tion) c an b e done aut oma tically, in lieu of ho oking a UDF . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2304Popula tion B alanc e ModelFor simple unidir ectional mass tr ansf er b etween pr imar y and sec ondar y phases due t o nuclea tion and growth phenomena of non-r eacting sp ecies , configur e the f ollowing settings: 1.Open the Phase In teraction dialo g box (Figur e 27.14: The P hase In teraction D ialog Box for N on-r eacting Species (p.2305 )). Setup → Models → Multiphase → Phases → Phase–In teractions Edit... 2.Specify the mass tr ansf er of sp ecies b etween the phases: Figur e 27.14: The P hase In teraction D ialo g Box for N on-r eac ting S pecies a.Under the Mass tab , specify the Numb er of M ass Transf er M echanisms involved in y our c ase. b.For each mechanism, specify the phase of the sour ce ma terial under From P hase and the phase of the destina tion ma terial phase under To Phase . c.From the Mechanism drop do wn list , selec t one of the mechanisms: none if you do not w ant an y mass tr ansf er b etween the phases . constan t-rate for a fix ed, user-sp ecified r ate. user-defined if you ho oked a UDF descr ibing the mass tr ansf er mechanism. 2305Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Popula tion B alanc e Model S etuppopula tion-balanc e for an aut oma ted metho d of mass tr ansf er, not in volving a UDF .The nuclea tion and the gr owth rates c alcula ted b y the p opula tion balanc e kernels ar e used f or mass tr ansf er. Note For the Inhomo geneous D iscr ete popula tion balanc e mo del, wher e ther e is mor e than one sec ondar y phase , you c an selec t population-balance as the mechanism of mass tr ansf er b etween the solv ent phase (sa y for cr ystalliza tion) and each of the solut e phases defined under the Inhomo geneous D iscr ete popula tion balanc e model. d.Click OK to sa ve the settings . For het erogeneous r eactions , configur e the f ollowing settings: 1.For the pr imar y phase , activate the Species Transp ort mo del. 2.Open the Phase In teraction dialo g box (Figur e 27.15: The P hase In teraction D ialog Box for a H eterogeneous Reaction (p.2306 )). Setup → Models → Multiphase → Phases → Phase–In teractions Edit... 3.Under the Reac tions tab , specify the st oichiometr y for the r eactant and the pr oduc t. Figur e 27.15: The P hase In teraction D ialo g Box for a H eterogeneous Reac tion 4.Selec t population-balance as the Reac tion R ate Func tion . 5.Click OK to sa ve the settings . Either this metho d or the use of the UDF , descr ibed in DEFINE_HET_RXN_RATE Macro (p.2317 ), will produce the same r esults . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2306Popula tion B alanc e ModelFor the Inhomo geneous D iscr ete popula tion balanc e mo del in volving nuclea tion and gr owth, you can selec t population-balance as the Reac tion R ate Func tion for each het erogeneous r eaction you ha ve set up .To lear n ho w to set up r eactions , go t o Specifying H eterogeneous R eactions (p.2106 ) in the User's G uide (p.1). 27.4. Postpr ocessing f or the P opula tion B alanc e M odel ANSY S Fluen t provides p ostpr ocessing options f or displa ying , plotting , and r eporting v arious par ticle quan tities , which include the main solution v ariables and other auxiliar y quan tities . 27.4.1. Popula tion B alanc e Solution Variables 27.4.2. Reporting D erived P opula tion B alanc e Variables 27.4.1. Popula tion B alanc e Solution Variables Solution v ariables tha t can b e reported f or the p opula tion balanc e mo del ar e: •Bin-i fr action (discr ete metho d only), wher e i is N-1 bins/momen ts. •Numb er densit y of Bin-i fr action (discr ete metho d only) •Diffusion C oef. of Bin-i fr action/M omen t-i •Sour ces of Bin-i fr action/M omen t-i •Momen t-i (SMM and QMOM only) •Abscissa-i (QMOM metho d only) •Weigh t-i (QMOM metho d only) Bin-i fr action ( ) is the t otal v olume fr action f or the th size bin when using the discr ete metho d. Numb er densit y of Bin-i fr action is the numb er densit y ( ) in for the th size bin. Momen t-i is the th momen t of the distr ibution when using the standar d metho d of momen ts or the quadr ature metho d of momen ts. Imp ortant Though the diffusion c oefficien ts of the p opula tion v ariables (f or e xample ,Diffusion C oef. of Bin-i fr action/M omen t-i) are available , the y are set t o zero because the diffusion t erm is not pr esen t in the p opula tion balanc e equa tions . 27.4.2. Rep orting D erived P opula tion B alanc e Variables Two options ar e available in the Results ribbon tab tha t allo w you t o report comput ed momen ts and numb er densit y on selec ted sur faces or c ell z ones of the domain. 27.4.2.1. Computing M omen ts 27.4.2.2. Displa ying a N umb er D ensit y Function 2307Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Postpr ocessing f or the P opula tion B alanc e Model27.4.2.1. Computing Moments You c an c omput e momen ts for the p opula tion balanc e mo del using the Popula tion B alanc e M omen ts dialo g box (Figur e 27.16: The P opula tion B alanc e M omen ts D ialog Box (p.2308 )). Results → Model S pecific → Popula tion B alanc e → Momen ts... Figur e 27.16: The P opula tion B alanc e M omen ts D ialo g Box The st eps f or c omputing momen ts ar e as f ollows: 1.For the discr ete metho d, specify the Numb er of M omen ts. For the SMM and QMOM, the numb er of momen ts is set equal t o the numb er of momen ts tha t were solv ed, and ther efore cannot b e changed . 2.For a sur face average, selec t the sur face(s) on which t o calcula te the momen ts in the Surfaces list. 3.For a v olume a verage, selec t the v olume(s) in which t o calcula te the momen ts in the Cell Z ones list. 4.Click Print to displa y the momen t values in the c onsole windo w. 5.To sa ve the momen t calcula tions t o a file , click Write... and en ter the appr opriate inf ormation in the resulting Selec t File dialo g box.The file e xtension should b e .pb . 27.4.2.2. Displa ying a Numb er D ensit y Func tion You c an displa y the numb er densit y func tion f or the p opula tion balanc e mo del using the Numb er Densit y Func tion dialo g box (Figur e 27.17: The N umb er D ensit y Function D ialog Box (p.2309 )). Results → Model S pecific → Popula tion B alanc e → Numb er D ensit y... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2308Popula tion B alanc e ModelFigur e 27.17: The N umb er D ensit y Func tion D ialo g Box The st eps f or displa ying the numb er densit y func tion ar e as f ollows: 1.Specify the Rep ort Type as either a Surface Average or a Volume A verage . 2.Under Plot Type, specify ho w you w ould lik e to displa y the numb er densit y func tion da ta. Hist ogram displa ys a hist ogram of the discr ete numb er densit y ( ).The numb er of divisions in the hist ogram is equal t o the numb er of bins sp ecified in the Popula tion B alanc e M odel dialo g box.This option is available only with the discr ete metho d. Curve displa ys a smo oth cur ve of the numb er densit y func tion. 3.(Quadr ature Momen t metho d only) S pecify Diamet er U pper Limit to reconstr uct the length or v olume- based numb er densit y func tion based on the momen ts pr edic ted b y QMOM (see Reconstr ucting the Particle S ize Distribution fr om M omen ts in the Fluent Theor y Guide for mor e inf ormation). The momen ts ar e calcula ted b y integrating the ar ea under the numb er densit y cur ve.The accur acy of the c alcula tions is dep enden t on the in tegration limit. Typic ally, this is e xpressed in t erms of the mean of the distr ibution and is sp ecified in the Diamet er U pper Limit field .The default v alue of 1.5 means tha t the maximum diamet er v alue c onsider ed is 1.5 times the mean of the distr ibution. 4.In the Fields list, selec t the da ta to be plott ed. Discr ete Numb er D ensit y ( ) is the numb er of par ticles p er unit v olume of ph ysical spac e in the th size bin plott ed against particle diamet er siz e .This option is a vailable only with the discr ete metho d. 2309Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Postpr ocessing f or the P opula tion B alanc e ModelLength N umb er D ensit y Func tion ( ) is the numb er of par ticles p er unit v olume of ph ysical spac e per unit par ticle length plott ed against par ticle diamet er. Volume N umb er D ensit y Func tion ( ) is the numb er of par ticles p er unit v olume of ph ysical spac e per unit par ticle v olume plott ed against par ticle v olume . 5.Choose the c ell z ones on which t o plot the numb er densit y func tion da ta in the Cell Z ones list. 6.Click Plot... to displa y the da ta. 7.(optional) C lick Print to displa y the numb er densit y func tion da ta in the c onsole windo w. 8.Click Write to sa ve the numb er densit y func tion da ta to a file .The Selec t File dialo g box will op en, wher e you c an sp ecify a name and sa ve a file c ontaining the plot da ta.The file e xtension should b e .pbd . 27.5. UDFs f or P opula tion B alanc e M odeling This sec tion c ontains the f ollowing sec tions: 27.5.1. Popula tion B alanc e Variables 27.5.2. Popula tion B alanc e DEFINE M acros 27.5.3. Hooking a P opula tion B alanc e UDF t o ANSY S Fluen t 27.5.1. Popula tion B alanc e Variables The macr os list ed in Table 27.1: Macros for P opula tion B alanc e Variables D efined in sg_pb.h (p.2310 ) can b e used t o retur n real variables asso ciated with the p opula tion balanc e mo del. The v ariables ar e available in b oth the pr essur e-based and densit y-based solv ers.The macr os ar e defined in the sg_pb.h header file , which is included in udf.h . Table 27.1: Macros f or P opula tion B alanc e Variables D efined in sg_pb.h Retur ns Argumen t Types Macro ( ) the t otal v olume fr action f or the th size bincell_t c, Thread *t, int iC_PB_DISCI th momen t cell_t c, Thread *t, int iC_PB_SMMI th momen t, wher e cell_t c, Thread *t, int iC_PB_QMOMI abscissa , wher e cell_t c, Thread *t, int iC_PB_QMOMI_L weigh t , wher e cell_t c, Thread *t, int iC_PB_QMOMI_W net sour ce term to th size bin cell_t c, Thread *t, int iC_PB_DISCI_PS net sour ce term to th momen t cell_t c, Thread *t, int iC_PB_SMMI_PS Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2310Popula tion B alanc e ModelRetur ns Argumen t Types Macro net sour ce term to th momen t cell_t c, Thread *t, int iC_PB_QMOMI_PS 27.5.2. Popula tion B alanc e DEFINE Macros This sec tion c ontains descr iptions of DEFINE macr os for the p opula tion balanc e mo del. Definitions of each DEFINE macr o ar e contained in the udf.h header file . 27.5.2.1. DEFINE_PB_BREAK_UP_R ATE_FREQ 27.5.2.2. DEFINE_PB_BREAK_UP_R ATE_PDF 27.5.2.3. DEFINE_PB_C OALESCENCE_R ATE 27.5.2.4. DEFINE_PB_NUCLEA TION_R ATE 27.5.2.5. DEFINE_PB_GR OWTH_R ATE 27.5.2.1.DEFINE_PB_BREAK_UP_RATE_FREQ You c an use the DEFINE_PB_BREAK_UP_RATE_FREQ macr o if y ou w ant to define the br eakage frequenc y using a UDF .The func tion is e xecut ed a t the b eginning of e very time st ep. 27.5.2.1.1. Usage DEFINE_PB_BREAK_UP_RATE_FREQ(name, cell, thread, d_1) Descr iption Argumen t Type UDF name char name Cell inde x cell_t cell Pointer to the sec ondar y phase thr ead asso ciated with d_1 Thread *thread Parent par ticle diamet er or length real d_1 Func tion r etur ns real There ar e four ar gumen ts to DEFINE_PB_BREAK_UP_RATE_FREQ :name ,cell ,thread , and d_1 .You will supply name , the name of the UDF .cell ,thread , and d_1 are variables tha t are passed b y the ANSY S Fluen t solv er to your UDF . 27.5.2.1.2. Example Included b elow is an e xample of a UDF tha t defines a br eakage fr equenc y (see Particle B irth and Death D ue t o Breakage and A ggregation ) tha t is based on the w ork of Tavlarides 107, such tha t (27.7) wher e and are constan ts, is the dissipa tion r ate, is the par ent diamet er, is the sur face tension, is the v olume fr action of the disp ersed phase , and is the densit y of the pr imar y phase . /************************************************************************ UDF that computes the particle breakage frequency *************************************************************************/ #include "udf.h" 2311Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.UDFs f or P opula tion B alanc e Modeling #include "sg_pb.h" #include "sg_mphase.h" DEFINE_PB_BREAK_UP_RATE_FREQ(break_up_freq_tav, cell, thread, d_1) { real epsi, alpha, f1, f2, rho_d; real C1 = 0.00481, C2 = 0.08, sigma = 0.07; Thread *tm = THREAD_SUPER_THREAD(thread);/*passed thread is phase*/ epsi = C_D(cell, tm); alpha = C_VOF(cell, thread); rho_d = C_R(cell, thread); f1 = pow(epsi, 1./3.)/((1.+epsi)*pow(d_1, 2./3.)); f2 = -(C2*sigma*(1.+alpha)*(1.+alpha))/(rho_d*pow(epsi,2./3.)*pow(d_1, 5./3.)); return C1*f1*exp(f2); } 27.5.2.2.DEFINE_PB_BREAK_UP_RATE_PDF You c an use the DEFINE_PB_BREAK_UP_RATE_PDF macr o if y ou w ant to define the br eakage PDF using a UDF .The func tion is e xecut ed a t the b eginning of e very time st ep. 27.5.2.2.1. Usage DEFINE_PB_BREAK_UP_RATE_PDF(name, cell, thread, d_1, thread_2, d_2) Descr iption Argumen t Type UDF name char name Cell inde x cell_t cell Pointer to the sec ondar y phase thr ead asso ciated with d_1 Thread *thread Parent par ticle diamet er or length real d_1 Pointer to the sec ondar y phase thr ead asso ciated with d_2 Thread *thread_2 Diamet er of one of the daugh ter par ticles af ter br eakage; the sec ond daugh ter par ticle diamet er is c alcula ted b y conser vation of par ticle volumereal d_2 Func tion r etur ns real There ar e six ar gumen ts to DEFINE_PB_BREAK_UP_RATE_PDF :name ,cell ,thread ,d_1 , thread_2 , and d_2 .You will supply name , the name of the UDF .cell ,thread ,d_1 ,thread_2 , and d_2 are variables tha t are passed b y the ANSY S Fluen t solv er to your UDF . Note thread and thread_2 are the same f or the D iscrete, QMOM and SMM mo dels .They may be the same or diff erent dep ending on whether d_1 and d_2 belong t o the same phase or diff erent phases f or the Inhomo geneous mo del. 27.5.2.2.2. Example Included b elow is an e xample of a UDF tha t defines a br eakage PDF (see Particle B irth and D eath Due t o Breakage and A ggregation ) tha t is par abolic, as defined in Equa tion 19.28 . /************************************************************************ UDF that computes the particle breakage PDF Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2312Popula tion B alanc e Model *************************************************************************/ #include "udf.h" #include "sg_pb.h" #include "sg_mphase.h" DEFINE_PB_BREAK_UP_RATE_PDF(break_up_pdf_par, cell, thread, d_1, thread_2, d_2) { real pdf; real kv = M_PI/6.; real C = 1.0; real f_2, f_3, f_4; real V_prime = kv*pow(d_1,3.); real V = kv*pow(d_2,3.); f_2 = 24.*pow(V/V_prime,2.); f_3 = -24.*(V/V_prime); f_4 = 6.; pdf = (C/V_prime) + ((1.-C/2.)/V_prime)*(f_2 + f_3 + f_4); return 0.5*pdf; } 27.5.2.3.DEFINE_PB_COALESCENCE_RATE You c an use the DEFINE_PB_COALESCENCE_RATE macr o if y ou w ant to define y our o wn par ticle aggr egation k ernel. The func tion is e xecut ed a t the b eginning of e very time st ep. 27.5.2.3.1. Usage DEFINE_PB_COALESCENCE_RATE(name, cell, thread, d_1, thread_2, d_2) Descr iption Argumen t Type UDF name char name Cell inde x cell_t cell Pointer to the sec ondar y phase thr ead asso ciated with d_1 Thread *thread Pointer to the sec ondar y phase thr ead asso ciated with d_2 Thread *thread_2 Diamet ers of the t wo colliding par ticles real d_1, d_2 Func tion r etur ns real There ar e six ar gumen ts to DEFINE_PB_COALESCENCE_RATE :name ,cell ,thread ,d_1 , thread_2 , and d_2 .You will supply name , the name of the UDF .cell ,thread ,d_1 , and d_2 are variables tha t are passed b y the ANSY S Fluen t solv er to your UDF .Your UDF will need t o retur n the real value of the aggr egation r ate. Note thread and thread_2 are the same f or the D iscrete, QMOM and SMM mo dels .They may be the same or diff erent dep ending on whether d_1 and d_2 belong t o the same phase or diff erent phases f or the Inhomo geneous mo del. 2313Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.UDFs f or P opula tion B alanc e Modeling27.5.2.3.2. Example Included b elow is an e xample UDF f or a B rownian aggr egation k ernel. In this e xample , the aggr egation rate is defined as wher e . /************************************************************************ UDF that computes the particle aggregation rate *************************************************************************/ #include "udf.h" #include "sg_pb.h" #include "sg_mphase.h" DEFINE_PB_COALESCENCE_RATE(aggregation_kernel,cell,thread,d_1,thread_2,d_2) { real agg_kernel; real beta_0 = 1.0e-17 /* aggregation rate constant */ agg_kernel = beta_0*pow((d_1+d_2),2.0)/(d_1*d_2); return agg_kernel; } 27.5.2.4.DEFINE_PB_NUCLEATION_RATE You c an use the DEFINE_PB_NUCLEATION_RATE macr o if y ou w ant to define y our o wn par ticle nuclea tion r ate.The func tion is e xecut ed a t the b eginning of e very time st ep. 27.5.2.4.1. Usage DEFINE_PB_NUCLEATION_RATE(name, cell, thread) Descr iption Argumen t Type UDF name char name Cell inde x cell_t cell Pointer to the sec ondar y phase thr ead Thread *thread Func tion r etur ns real There ar e thr ee ar gumen ts to DEFINE_PB_NUCLEATION_RATE :name ,cell , and thread .You will supply name , the name of the UDF .cell and thread are variables tha t are passed b y the ANSY S Fluen t solv er to your UDF .Your UDF will need t o retur n the real value of the nuclea tion rate. 27.5.2.4.2. Example Potassium chlor ide c an b e cr ystalliz ed fr om w ater b y cooling . Its solubilit y decr eases linear ly with temp erature. Assuming p ower-la w kinetics f or the nuclea tion r ate, Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2314Popula tion B alanc e Modelwher e and . /************************************************************************ UDF that computes the particle nucleation rate *************************************************************************/ #include "udf.h" #include "sg_pb.h" #include "sg_mphase.h" DEFINE_PB_NUCLEATION_RATE(nuc_rate, cell, thread) { real J, S; real Kn = 4.0e10; /* nucleation rate constant */ real Nn = 2.77; /* nucleation law power index */ real T,solute_mass_frac,solvent_mass_frac, solute_mol_frac,solubility; real solute_mol_wt, solvent_mol_wt; Thread *tc = THREAD_SUPER_THREAD(thread); /*obtain mixture thread */ Thread **pt = THREAD_SUB_THREADS(tc); /* pointer to sub_threads */ Thread *tp = pt[P_PHASE]; /* primary phase thread */ solute_mol_wt = 74.55; /* molecular weight of potassium chloride */ solvent_mol_wt = 18.; /* molecular weight of water */ solute_mass_frac = C_YI(cell,tp,0); /* mass fraction of solute in primary phase (solvent) */ solvent_mass_frac = 1.0 - solute_mass_frac; solute_mol_frac = (solute_mass_frac/solute_mol_wt)/ ((solute_mass_frac/solute_mol_wt)+(solvent_mass_frac/solvent_mol_wt)); T = C_T(cell,tp); /* Temperature of primary phase in Kelvin */ solubility = 0.0005*T-0.0794; /* Solubility Law relating equilibrium solute mole fraction to Temperature*/ S = solute_mol_frac/solubility; /* Definition of Supersaturation */ if (S == 1.) { J = 0.; } else { J = Kn*pow((S-1),Nn); } return J; } Imp ortant Note tha t the solubilit y and the chemistr y could b e defined in a separ ate routine and simply c alled fr om the ab ove func tion. 27.5.2.5.DEFINE_PB_GROWTH_RATE You c an use the DEFINE_PB_GROWTH_RATE macr o if y ou w ant to define y our o wn par ticle gr owth rate.The func tion is e xecut ed a t the b eginning of e very time st ep. 27.5.2.5.1. Usage DEFINE_PB_GROWTH_RATE(name, cell, thread,d_i) Descr iption Argumen t Type UDF name char name 2315Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.UDFs f or P opula tion B alanc e ModelingDescr iption Argumen t Type Cell inde x cell_t cell Pointer to the sec ondar y phase thr ead Thread *thread Particle diamet er or length real d_i Func tion r etur ns real There ar e four ar gumen ts to DEFINE_PB_GROWTH_RATE :name ,cell ,thread , and d_i .You will supply name , the name of the UDF .cell ,thread , and d_i are variables tha t are passed b y the ANSY S Fluen t solv er to your UDF .Your UDF will need t o retur n the real value of the gr owth rate. 27.5.2.5.2. Example Potassium chlor ide c an b e cr ystalliz ed fr om w ater b y cooling . Its solubilit y decr eases linear ly with temp erature. Assuming p ower-la w kinetics f or the gr owth r ate, wher e m/s and . /************************************************************************ UDF that computes the particle growth rate *************************************************************************/ #include "udf.h" #include "sg_pb.h" #include "sg_mphase.h" DEFINE_PB_GROWTH_RATE(growth_rate, cell, thread,d_1) { /* d_1 can be used if size-dependent growth is needed */ /* When using SMM, only size-independent or linear growth is allowed */ real G, S; real Kg = 2.8e-8; /* growth constant */ real Ng = 1.; /* growth law power index */ real T,solute_mass_frac,solvent_mass_frac, solute_mol_frac,solubility; real solute_mol_wt, solvent_mol_wt; Thread *tc = THREAD_SUPER_THREAD(thread); /*obtain mixture thread */ Thread **pt = THREAD_SUB_THREADS(tc); /* pointer to sub_threads */ Thread *tp = pt[P_PHASE]; /* primary phase thread */ solute_mol_wt = 74.55; /* molecular weight of potassium chloride */ solvent_mol_wt = 18.; /* molecular weight of water */ solute_mass_frac = C_YI(cell,tp,0); /* mass fraction of solute in primary phase (solvent) */ solvent_mass_frac = 1.0 - solute_mass_frac; solute_mol_frac = (solute_mass_frac/solute_mol_wt)/ ((solute_mass_frac/solute_mol_wt)+(solvent_mass_frac/solvent_mol_wt)); T = C_T(cell,tp); /* Temperature of primary phase in Kelvin */ solubility = 0.0005*T-0.0794; /* Solubility Law relating equilibrium solute mole fraction to Temperature*/ S = solute_mol_frac/solubility; /* Definition of Supersaturation */ if (S == 1.) { G = 0.; } else { Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2316Popula tion B alanc e Model G = Kg*pow((S-1),Ng); } return G; } Imp ortant Note tha t the solubilit y and the chemistr y could b e defined in a separ ate routine and simply c alled fr om the ab ove func tion. 27.5.3. Hooking a P opula tion B alanc e UDF t o ANSY S Fluen t After the UDF tha t you ha ve defined using DEFINE_PB_BREAK_UP_RATE_FREQ ,DEFINE_PB_ BREAK_UP_RATE_PDF ,DEFINE_PB_COALESCENCE_RATE ,DEFINE_PB_NUCLEATION_RATE , or DEFINE_PB_GROWTH_RATE is in terpreted or c ompiled , the name tha t you sp ecified in the DEFINE macr o ar gumen t (for e xample ,agg_kernel ) will b ecome visible and selec table in the appr opriate drop-do wn list under Phenomena in the Popula tion B alanc e M odel dialo g box (Figur e 27.1: The Popula tion B alanc e M odel D ialog Box (p.2287 )). 27.6.DEFINE_HET_RXN_RATE Macro This sec tion discusses the DEFINE_HET_RXN_RATE macr o: 27.6.1. Descr iption 27.6.2. Usage 27.6.3. Example 27.6.4. Hooking a H eterogeneous R eaction R ate UDF t o ANSY S Fluen t 27.6.1. Descr iption You need t o use DEFINE_HET_RXN_RATE to sp ecify r eaction r ates for het erogeneous r eactions . A heterogeneous r eaction is one tha t involves reactants and pr oduc ts fr om mor e than one phase . Unlike DEFINE_VR_RATE , a DEFINE_HET_RXN_RATE UDF c an b e sp ecified diff erently f or diff erent het ero- geneous r eactions . During ANSY S Fluen t execution, the DEFINE_HET_RXN_RATE UDF f or each het erogeneous r eaction that is defined is c alled in e very fluid c ell. ANSY S Fluen t will use the r eaction r ate sp ecified b y the UDF to comput e pr oduc tion/destr uction of the sp ecies par ticipa ting in the r eaction, as w ell as hea t and momen tum tr ansf er acr oss phases due t o the r eaction. A het erogeneous r eaction is t ypic ally used t o define r eactions in volving sp ecies of diff erent phases . The bulk phase c an par ticipa te in the r eaction if the phase do es not ha ve an y sp ecies (tha t is, the phase has fluid ma terial inst ead of mix ture ma terial). Heterogeneous r eactions ar e defined in the Phase Interaction dialo g box. 27.6.2. Usage DEFINE_HET_RXN_RATE (name,c,t,r,mw,yi,rr,rr_t ) Descr iption Argumen t Type UDF name char name 2317Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.DEFINE_HET_RXN_RATE MacroCell inde x cell_t c Cell thr ead (mix ture level) on which het erogeneous reaction r ate is t o be appliedThread *t Pointer to da ta str ucture tha t represen ts the cur rent heterogeneous r eaction (see sg_mphase.h )Hetero_Reaction *r Matrix of sp ecies molecular w eigh ts.mw[i][j] will giv e molecular w eigh t of sp ecies with ID j in phase withreal mw[MAX_PHASES][MAX_SPE_EQNS] inde x i. For phase tha t has fluid ma terial, the molecular weigh t can b e acc essed as mw[i][0] . Matrix of sp ecies mass fr actions .yi[i][j] will giv e molecular w eigh t of sp ecies with ID j in phase withreal yi[MAX_PHASES][MAX_SPE_EQNS] inde x i. For phase tha t has fluid ma terial,yi[i][0] will b e 1. Pointer to laminar r eaction r ate real *rr Currently not used . Provided f or futur e use . real *rr_t Func tion r etur ns void There ar e eigh t argumen ts to DEFINE_HET_RXN_RATE :name ,c,t,r,mw,yi,rr, and rr_t .You will supply name , the name of the UDF .c,t,r,mw,yi,rr, and rr_t are variables tha t are passed by the ANSY S Fluen t solv er to your UDF .Your UDF will need t o set the v alues r eferenced b y the real pointer rr. 27.6.3. Example The f ollowing c ompiled UDF , named arrh , defines an A rrhenius-t ype reaction r ate.The r ate exponen ts are assumed t o be same as the st oichiometr ic coefficien ts. #include "udf.h" static const real Arrhenius = 1.e15; static const real E_Activation = 1.e6; #define SMALL_S 1.e-29 DEFINE_HET_RXN_RATE(arrh,c,t,hr,mw,yi,rr,rr_t) { Domain **domain_reactant = hr->domain_reactant; real *stoich_reactant = hr->stoich_reactant; int *reactant = hr->reactant; int i; int sp_id; int dindex; Thread *t_reactant; real ci; real T = 1200.; /* should obtain from cell */ /* instead of compute rr directly, compute log(rr) and then take exp */ *rr = 0; for (i=0; i < hr->n_reactants; i++) { sp_id = reactant[i]; /* species ID to access mw and yi */ if (sp_id == -1) sp_id = 0; /* if phase does not have species, mw, etc. will be stored at index 0 */ dindex = DOMAIN_INDEX(domain_reactant[i]); /* domain index to access mw & yi */ t_reactant = THREAD_SUB_THREAD(t,dindex); Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2318Popula tion B alanc e Model /* get conc. */ ci = yi[dindex][sp_id]*C_R(c,t_reactant)/mw[dindex][sp_id]; ci = MAX(ci,SMALL_S); *rr += stoich_reactant[i]*log(ci); } *rr += log(Arrhenius + SMALL_S) - E_Activation/(UNIVERSAL_GAS_CONSTANT*T); /* 1.e-40 < rr < 1.e40 */ *rr = MAX(*rr,-40); *rr = MIN(*rr,40); *rr = exp(*rr); } 27.6.4. Hooking a H eterogeneous Reac tion R ate UDF t o ANSY S Fluen t After the UDF tha t you ha ve defined using DEFINE_HET_RXN_RATE is in terpreted or c ompiled (see the Fluen t Customiza tion M anual for details), the name tha t you sp ecified in the DEFINE macr o ar gu- men t (for e xample ,arrh ) will b ecome visible and selec table under Reac tion R ate Func tion in the Reac tions tab of the Phase In teraction dialo g box. (Note you will first need t o sp ecify the Total Numb er of Reac tions greater than 0.) 2319Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.DEFINE_HET_RXN_RATE MacroRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2320Chapt er 28: Modeling S olidific ation and M elting This chapt er descr ibes ho w you c an mo del solidific ation and melting in ANSY S Fluen t. For inf ormation about the theor y behind the mo del, see Solidific ation and M elting in the Theor y Guide . Information about using the mo del is or ganiz ed in to the f ollowing sec tions: 28.1. Setup P rocedur e 28.2. Procedur es for M odeling C ontinuous C asting 28.3. Modeling Thermal and S olutal B uoyancy 28.4. Solution P rocedur e 28.5. Postpr ocessing 28.1. Setup P rocedur e The pr ocedur e for setting up a solidific ation/melting pr oblem is descr ibed b elow. (Note tha t this pr o- cedur e includes only those st eps nec essar y for the solidific ation/melting mo del itself ; you will need t o set up other mo dels , boundar y conditions , and so on, as usual.) 1.To use the solidific ation/melting mo del, enable the Solidific ation/M elting option in the Solidific ation and M elting dialo g box (Figur e 28.1: The S olidific ation and M elting D ialog Box (p.2321 )). Setup → Models → Solidific ation & M elting Edit... Figur e 28.1: The S olidific ation and M elting D ialo g Box ANSY S Fluen t will aut oma tically enable the ener gy equa tion, so y ou do not ha ve to visit the Energy dialo g box before tur ning on the solidific ation/melting mo del. 2321Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.2.Under Paramet ers, specify the v alue of the Mush y Zone P aramet er ( in Equa tion 20.6 ) as a constan t, or as a user-defined func tion. Refer to DEFINE_SOLIDIFICATION_PARAMS in the Fluen t Customiza tion Manual for detailed inf ormation ab out the user-defined func tion. Values b etween and are recommended f or most c omputa tions .The higher the v alue of the Mush y Zone P aramet er, the st eeper the damping cur ve becomes , and the fast er the v elocity dr ops to zero as the ma terial solidifies .Very lar ge v alues ma y cause the solution t o oscilla te as c ontrol volumes alt ernately solidify and melt with minor p erturba tions in liquid v olume fr action. 3.If you w ant to include the pull v elocity in y our simula tion (as descr ibed in Momen tum E qua tions and Pull Velocity for C ontinuous C asting in the Theor y Guide ), enable the Include P ull Velocities option under Paramet ers. 4.If you ar e including pull v elocities and y ou w ant ANSY S Fluen t to comput e them (using Equa tion 20.22 ) based on the sp ecified v elocity boundar y conditions , as descr ibed in Pull Velocity for C ontinuous C asting in the Theor y Guide , enable the Comput e Pull Velocities option and sp ecify the numb er of Flow Iterations Per P ull Velocity Iteration . Imp ortant It is not nec essar y to ha ve ANSY S Fluen t comput e the pull v elocities . See Procedur es for Modeling C ontinuous C asting (p.2324 ) for inf ormation ab out other appr oaches . The default v alue of 1 f or the Flow Iterations P er P ull Velocity Iteration indic ates tha t the pull velocity equa tions will b e solv ed af ter each it eration of the solv er. If you incr ease this v alue , the pull velocity equa tions will b e solv ed less fr equen tly.You ma y want to incr ease the numb er of Flow It- erations P er P ull Velocity Iteration if the liquid fr action equa tion is almost c onverged (tha t is, the position of the liquid-solid in terface is not changing v ery much). This will sp eed up the c alcula tion, although the r esiduals ma y jump when the pull v elocities ar e up dated. 5.Under Options , selec t either Lever R ule or Scheil R ule. See Species E qua tions in the Theor y Guide for details . Imp ortant The Lever R ule and Scheil R ule options ar e available only when Species Transp ort is enabled in the Species M odel dialo g box. 6.If you selec t Scheil R ule, then y ou c an enable Back D iffusion . Enter either a constan t or a user-defined func tion t o sp ecify the v alue of the Back D iffusion P aramet er ( in Equa tion 20.19 ). Refer to DEFINE_SOLIDIFICATION_PARAMS in the Fluen t Customiza tion M anual for detailed inf ormation ab out the user-defined func tion. Note tha t the v alue f or the Back D iffusion P aramet er must b e between 0 and 1. 7.In the Create/Edit M aterials D ialog Box (p.3386 ) (Figur e 28.2: The C reate/Edit M aterials D ialog Box for M elting and S olidific ation (p.2323 )), specify the Pure Solvent Melting H eat ( in Equa tion 20.4 ),Solidus Temp erature ( in Equa tion 20.3 ), and Liquidus Temp erature ( in Equa tion 20.3 ) for the ma terial b eing used in y our mo del. Setup → Materials Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2322Modeling S olidific ation and M eltingFigur e 28.2: The C reate/Edit M aterials D ialo g Box for M elting and S olidific ation If you ar e solving f or sp ecies tr ansp ort, you need t o sp ecify pr operties f or the mix ture, including the metho d by which the Solidus Temp erature and the Liquidus Temp erature are calcula ted.The default metho d is the mixing-la w (Equa tion 20.8 and Equa tion 20.9 in the Theor y Guide ), in which the solidus t emp erature and the liquidus t emp erature ar e calcula ted fr om the par amet ers pr ovided for each solut e (such as the slop e of the liquidus line or par tition c oefficien t). However, a user- defined func tion of t ype DEFINE_PROPERTY can b e used t o sp ecify b oth of these t emp eratures. See the Fluen t Customiza tion M anual for e xamples of DEFINE_PROPERTY . Imp ortant It is highly r ecommended tha t you use the same metho d for sp ecifying the Solidus Temp erature and the Liquidus Temp erature. When defining the mix ture, you will also sp ecify the Mass D iffusivit y ( in Equa tion 20.15 and Equa tion 20.18 ) and the Eutectic Temp erature ( in Equa tion 20.10 ), as w ell as the Pure Solvent Melting H eat ( in Equa tion 20.4 ) and the Pure Solvent Melting Temp erature ( in Equa tion 20.8 and Equa tion 20.9 ). Note tha t the solv ent is the last sp ecies list ed under Selec ted S pecies in the Species dialo g box. For each solut e, you ha ve to sp ecify the Slope of Liquidus Line ( in Equa tion 20.8 and Equa tion 20.9 in the Theor y Guide ) with r espect to the c oncentration of the solut e, the Partition C oefficien t ( in Equa tion 20.8 ), the Eutectic M ass F raction ( in Equa tion 20.10 ), and , if Lever R ule is selec ted in the Solidific ation and M elting dialo g box, the c oefficien t for Diffusion in S olid ( in Equa tion 20.15 ). It is not nec essar y to sp ecify , , , and for the solv ent. 2323Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setup P rocedur e8.Set the b oundar y conditions . Setup → Boundar y Conditions In addition t o the usual b oundar y conditions , consider the f ollowing: •If you w ant to acc oun t for the pr esenc e of an air gap b etween a w all and an adjac ent solidified r egion (as descr ibed in Contact Resistanc e at Walls in the Theor y Guide), specify a nonz ero value , a pr ofile , or a user-defined func tion f or Contact Resistanc e ( in Equa tion 20.23 ) under Thermal C onditions in the Wall D ialog Box (p.3549 ). •If you w ant to sp ecify the gr adien t of the sur face tension with r espect to the t emp erature at a w all boundar y, you c an use the Marangoni S tress option f or the w all Shear C ondition . See Marangoni Stress (p.977) for details . •If you w ant ANSY S Fluen t to comput e the pull v elocities dur ing the c alcula tion, not e ho w your sp ecified velocity conditions ar e used in this c alcula tion (see Pull Velocity for C ontinuous C asting in the Theor y Guide ). Procedur es for M odeling C ontinuous C asting (p.2324 ) contains additional inf ormation ab out mo deling continuous c asting . See Solution P rocedur e (p.2326 ) and Postpr ocessing (p.2326 ) for inf ormation ab out solving a solidific ation/melting mo del and p ostpr ocessing the r esults . 28.2. Procedur es for M odeling C ontinuous C asting As descr ibed in Momen tum E qua tions and Pull Velocity for C ontinuous C asting in the Theor y Guide , you c an include the pull v elocities in y our solidific ation/melting c alcula tion t o mo del c ontinuous c asting . There ar e thr ee appr oaches t o mo deling c ontinuous c asting in ANSY S Fluen t: •Specify c onstan t or v ariable pull v elocities . To use this appr oach (the default), do not enable the Comput e Pull Velocities option. If you use this appr oach, you will need t o pa tch c onstan t values or cust om field func tions f or the pull velocities , after y ou initializ e the solution. Solution → Initializa tion → Patch... See Patching Values in S elec ted C ells (p.2607 ) for details ab out pa tching v alues . Note tha t it is acc eptable to pa tch v alues f or the pull v elocities in the en tire domain, because the pa tched v alues will b e used only if the liquid fr action, , is less than 1. •Have ANSY S Fluen t comput e the pull v elocities (using Equa tion 20.22 ) dur ing the c alcula tion, based on the specified v elocity boundar y conditions . To use this appr oach, enable the Comput e Pull Velocities option. This metho d is c omputa tionally expensiv e, and is r ecommended only if the pull v elocities ar e str ongly dep enden t on the lo cation of the liquid-solid in terface. If you ha ve ANSY S Fluen t comput e the pull v elocities , then ther e ar e no additional inputs or setup procedur es b eyond those pr esen ted in Setup P rocedur e (p.2321 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2324Modeling S olidific ation and M elting•Have ANSY S Fluen t comput e the pull v elocities just onc e, and then use those v alues f or the r emainder of the c alcula tion. To use this appr oach, perform one it eration with ANSY S Fluen t computing the pull v elocities , and then tur n off the Comput e Pull Velocities option and c ontinue the c alcula tion. For the r emainder of the c alcula tion, ANSY S Fluen t will use the v alues c omput ed f or the pull v elocities a t the first it eration. 28.3. Modeling Thermal and S olutal Buo yanc y When the eff ects of ther mal and solutal buo yancy are pr esen t, a flo w can b e induc ed inside the domain due t o the eff ect of gr avity on the v ariable densit y of the medium. In the c ase of multi-c omp onen t so- lidific ation pr oblems , the densit y variation tak es plac e due t o temp erature changes and also due t o species c oncentration gr adien ts near the liquid-solid in terface.The flo w due t o buo yancy with solidific- ation and melting c an b e mo deled in ANSY S Fluen t using the ther mal and solutal buo yancy options . For mor e inf ormation on the theor y behind buo yancy induc ed flo w in solidific ation and melting pr oblems , see Thermal and S olutal B uoyancy in the Theor y Guide . The pr ocedur e for setting up a solidific ation/melting pr oblem is descr ibed in Setup P rocedur e (p.2321 ). To include ther mal and solutal buo yancy eff ects, perform the f ollowing st eps: 1.Enable the Include Thermal Buo yanc y and Include S olutal Buo yanc y options in the Solidific ation and M elting dialo g box (Figur e 28.3: The S olidific ation and M elting D ialog Box (p.2325 )). Note The Include Thermal Buo yanc y and Include S olutal Buo yanc y options ar e available only when solidific ation is mo deled with sp ecies tr ansp ort. Figur e 28.3: The S olidific ation and M elting D ialo g Box 2.Define the op erating c onditions and pr operties f or mo deling ther mal buo yancy as descr ibed in Nat- ural Convection and B uoyancy-Driven F lows (p.1476 ). 2325Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modeling Thermal and S olutal B uoyancy3.To mo del solutal buo yancy, specify a v alue f or the Solutal E xpansion C oefficien t for all the sp ecies except the last one in the mix ture in the Create/Edit M aterials dialo g box. Note By default , the eut ectic mass fr action of the solut e is used as the r eference sp ecies mass fraction of the solut e for the c alcula tion of the b ody force due t o solutal buo yancy. Therefore, no additional input is r equir ed. However, in c ertain applic ations , it is not alw ays desir able t o use the default v alues of the r eference mass fr action. For such c ases , the solut e mass fr action v alues c an b e en tered thr ough t ext user in terface as f ollows: define/models/solidification-melting? yes Include Thermal Buoyancy? yes Include Solutal Buoyancy? yes Use reference mass fraction of solutes? yes Reference mass fraction of the species-i "value" 28.4. Solution P rocedur e Before solving the c oupled fluid flo w and hea t transf er pr oblem, you ma y want to pa tch an initial temp erature or solv e the st eady conduc tion pr oblem as an initial c ondition. The c oupled pr oblem c an then b e solv ed as either st eady or tr ansien t. Because of the nonlinear na ture of these pr oblems , however, in most c ases a tr ansien t solution appr oach is pr eferred. You c an sp ecify the under-r elaxa tion fac tor applied t o the liquid fr action equa tion in the Solution Controls Task P age (p.3606 ). Solution → Controls Specify the desir ed v alue in the Liquid F raction U pdate field under Under-Relaxa tion F actors.This sets the v alue of in the f ollowing equa tion f or up dating the liquid fr action fr om one it eration ( ) to the ne xt ( ): (28.1) wher e is the pr edic ted change in liquid fr action. In man y cases , ther e is no need t o change the default v alue of . If, however, ther e ar e convergenc e difficulties , reducing the v alue ma y impr ove the solution c onvergenc e. Convergenc e difficulties c an b e expected in st eady-sta te calcula tions , continuous c asting simula tions , simula tions in volving multic om- ponen t solidific ation, and simula tions wher e a lar ge v alue of the mush y zone c onstan t is used . 28.5. Postpr ocessing For solidific ation/melting c alcula tions , you c an gener ate gr aphic al plots or alphanumer ic reports of the following it ems dep ending on which other mo dels ar e enabled in the simula tion. These quan tities ar e available in the Solidific ation/M elting ... categor y of the v ariable selec tion dr op-do wn list tha t app ears in p ostpr ocessing dialo g boxes: •Liquid F raction •Contact Resistivit y Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2326Modeling S olidific ation and M elting•Pull Velocity (X,Y,Z,Axial ,Radial , and Swirl comp onen ts) •Liquidus Temp erature •Solidus Temp erature The Liquid F raction and Contact Resistivit y solution v ariables ar e available f or all solidific ation/melting simula tions .The Pull Velocity comp onen ts ar e available only if y ou ar e including pull v elocities (either comput ed or sp ecified) in the simula tion. Liquidus Temp erature and Solidus Temp erature are available only if the Species mo del is set up t o perform a multi-c omp onen t solidific ation/melting simula tion. See Field F unction D efinitions (p.2959 ) for a c omplet e list of field func tions and their definitions .Displa ying Graphics (p.2775 ) and Reporting A lphanumer ic D ata (p.2909 ) explain ho w to gener ate gr aphics displa ys and r eports of da ta. Figur e 28.4: Liquid F raction C ontours f or C ontinuous C rystal G rowth (p.2327 ) sho ws filled c ontours of liquid fraction f or a c ontinuous cr ystal gr owth simula tion. Figur e 28.4: Liquid F raction C ontours f or C ontinuous C rystal G rowth 2327Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Postpr ocessingRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2328Chapt er 29: Modeling F luid-S tructure Interaction (FSI) Within F luen t This chapt er pr ovides details ab out ho w to mo del and simula te one-w ay and t wo-w ay fluid-str ucture interaction (FSI) c omplet ely within a F luen t session. This is r eferred t o as "in trinsic FSI", as all of the structural calcula tions ar e performed b y Fluen t; not e tha t you c an also use e xtrinsic solv ers f or FSI problems , incorporating the str uctural da ta in to your F luen t fluid simula tion thr ough mapping or sy stem coupling , as descr ibed in Mapping D ata for F luid-S tructure In teraction (FSI) A pplic ations (p.640) and Performing S ystem C oupling S imula tions U sing F luen t (p.3207 ), respectively.The theor etical asp ects of intrinsic FSI c alcula tions ar e pr esen ted in The S tructural M odel f or In trinsic F luid-S tructure In teraction (FSI) in the Theor y Guide .The f ollowing sec tions pr ovide details on r unning in trinsic FSI simula tions: 29.1. Overview and Limita tions 29.2. Setting U p an In trinsic F luid-S tructure Interaction (FSI) S imula tion 29.1. Overview and Limita tions Intrinsic fluid-str ucture in teraction (FSI) c apabilities allo w you t o simula te either one-w ay or t wo-w ay FSI pr oblems c omplet ely within a F luen t session. One-w ay FSI pr oblems assume tha t only the fluid side will ha ve an impac t on the solid side thr ough the fluid f orce tha t acts on the str ucture. Since ther e is no f eedback inf ormation fr om the solid side , for one-w ay FSI simula tions y ou c an either c omput e the fluid flo w and str uctural def ormation simultaneously , or c omput e the str uctural side indep enden tly after the fluid simula tion is c omplet ed. However, if the solid domain influenc es the fluid side of the FSI simula tion, then y ou must mo del it as a t wo-w ay FSI simula tion b y enabling mesh motion f or the fluid domain thr ough a d ynamic mesh. The solution of an FSI pr oblem r equir es the solution of b oth the fluid flo w pr oblem as w ell as the structural pr oblem. The solution of the str uctural equa tions is limit ed b y following: •The str uctural mo del only supp orts quadr ilateral and/or tr iangular c ell types in 2D and he xahedr al and/or tetrahedr al cell types in 3D .This applies only t o the solid z ones . Note If you use the meshing mo de of F luen t to gener ate a he xcore mesh, the r esulting mesh will not b e suitable f or the str uctural mo del, as such meshes c ontain small numb ers of polyhedr al cells. •The fluid and solid z ones must ha ve conformal meshes and b e separ ated b y two-sided w alls (tha t is, wall / wall-shado w pairs). •At least one solid z one must b e pr esen t in the domain in or der t o enable the str uctural mo del. •The following d ynamic mesh options ar e not supp orted f or in trinsic FSI pr oblems: –In-C ylinder 2329Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.–Six DOF –Contact Detection •The Intrinsic FSI type can only b e selec ted in the Dynamic M esh Z ones dialo g box for the side of a t wo- sided w all (tha t is, the w all or w all-shado w) tha t is immedia tely adjac ent to the fluid c ell z one (as indic ated by the Adjac ent Cell Z one field in the Wall dialo g box). •For a w all tha t is adjac ent to a solid z one or b etween a solid and fluid z one: –The only user-defined func tions (UDFs) tha t are supp orted f or displac emen t and f orce are DEFINE_WALL_NODAL_DISP and DEFINE_WALL_NODAL_FORCE , respectively (as descr ibed in DEFINE_WALL_NODAL_DISP and DEFINE_WALL_NODAL_FORCE ). All other b oundar y condition profiles or UDFs (such as DEFINE_PROFILE ) will pr oduce an er ror message . –The Shell C onduc tion option is not supp orted. •The str uctural mo del is not c ompa tible with: –the 2D Axisymmetr ic or Axisymmetr ic Swirl option –mesh adaption –overset meshes –the mesh mor pher/optimiz er –British or c entimet er-gr am-sec ond (C GS) units –FMG initializa tion –adaptiv e time st epping •The str uctural mo del is not a vailable when r unning F luen t under ANSY S Workbench. •The Linear E lasticit y structural mo del is only appr opriate when the str ess loading do es not e xceed the yield strength of the solid ma terial. 29.2. Setting U p an In trinsic F luid-S tructure In teraction (FSI) S imula tion The pr ocedur e for setting up an in trinsic FSI simula tion is descr ibed b elow. Note tha t only st eps tha t are pertinen t to the str uctural mo del ar e list ed her e.You will also need t o define the other settings (such as other ma terial pr operties, boundar y conditions , other mo dels) as usual. For inf ormation ab out inputs r elated t o other ANSY S Fluen t mo dels tha t you ar e using in c onjunc tion with the in trinsic FSI simula tion, refer to the appr opriate sec tions f or those mo dels . 1.(recommended) Launch the double-pr ecision v ersion of ANSY S Fluen t. 2.Define the settings in the Gener al task page . Setup → Gener al Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2330Modeling F luid-S tructure Interaction (FSI) Within F luen ta.Define the time dep endenc e of the simula tion: one-w ay FSI pr oblems c an b e Stead y or Transien t, wher eas t wo-w ay FSI pr oblems must b e Transien t. Note tha t mo deling t wo-w ay FSI is only nec essar y when the def ormation of the solid z one is signific ant enough t o aff ect the fluid flo w. b.You c an enable the Gravity option and define the c oordina tes for the acc eleration if y ou w ould lik e the str uctural mo del t o acc oun t for gr avitational f orces when c alcula ting the def ormation of the solid cell z one . 3.Define a solid z one . Setup → Cell Z one C onditions Note tha t you c an enable the Frame M otion option in the Solid dialo g box and define a r otational velocity for the r eference frame if y ou w ould lik e the str uctural mo del t o acc oun t for rotational forces when c alcula ting the def ormation of the solid c ell z one . For details , see Defining Z one M o- tion (p.861) and Modeling F lows with M oving R eference Frames (p.1227 ). 4.For a t wo-w ay FSI pr oblem, it is r ecommended tha t you r un the c alcula tion a t this p oint to obtain a c on- verged solution f or the fluid , and then pr oceed with the f ollowing st eps t o set up and r un the str uctural model. 5.In the Structural M odel dialo g box, selec t the Linear E lasticit y mo del. This mo del enables str uctural cal- cula tions f or the solid c ell z one such tha t the in ternal load is linear ly pr oportional t o the no dal displac emen t, and the str uctural stiffness ma trix remains c onstan t. Setup → Models → Structure Edit... Figur e 29.1: The S tructural M odel D ialo g Box 6.Make sur e tha t the ma terial used in the solid c ell z one is pr operly defined , by setting the Youngs M odulus and Poisson R atio fields in the Properties group b ox of the Create/Edit M aterials dialo g box. Setup → Materials 7.If you plan t o define the displac emen t or f orce applied t o the no des of a w all adjac ent to the solid z one using a user-defined func tion (UDF), interpret or c ompile a suitable UDF . For details , see DEFINE_WALL_NODAL_DISP or DEFINE_WALL_NODAL_FORCE , respectively. 8.For e very wall tha t is immedia tely adjac ent to the solid z one , define the displac emen t boundar y condition settings in the Structure tab of the Wall dialo g box. 2331Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p an In trinsic F luid-S tructure Interaction (FSI) S imula tionSetup → Boundar y Conditions Figur e 29.2: The S tructure Tab of the Wall D ialo g Box The w alls will b e one-sided when the y are only adjac ent to a solid c ell z one , and will b e two-sided (tha t is, a w all / w all-shado w pair) when the y are adjac ent to both a solid and a fluid c ell z one . Note that for two-sided w alls, the Structure tab is only a vailable f or one side of the w all / w all-shado w pair ; which one will dep end on ho w the mesh w as set up . You must selec t one of the f ollowing fr om the X-,Y-, and (f or 3D c ases) Z-D isplac emen t Boundar y Condition drop-do wn lists , in or der t o define ho w the displac emen t is c alcula ted f or the no des in that par ticular dir ection: •Stress F ree specifies tha t the displac emen t is not aff ected b y str ess loads fr om the fluid flo w. •Node X- ,Node Y-, and (f or 3D c ases) Node Z-F orce specifies tha t the displac emen t results fr om a sp ecified force applied on the no des, which is defined using the Node X- ,Node Y-, and (f or 3D c ases) Node Z- Force field . •Node X- ,Node Y-, and (f or 3D c ases) Node Z-D isplac emen t applies a sp ecified displac emen t on the nodes, which is defined using the X-,Y-, and (f or 3D c ases) Z-D isplac emen t field . •Face Pressur e specifies tha t the displac emen t results fr om a sp ecified pr essur e load applied on the faces, which is defined using the Face Pressur e field . •Intrinsic FSI specifies tha t the displac emen t results fr om pr essur e loads e xerted b y the fluid flo w on the faces. Note tha t this selec tion is only a vailable f or a z one tha t is par t of a w all / w all-shado w pair . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2332Modeling F luid-S tructure Interaction (FSI) Within F luen tFigur e 29.3: The Wall D ialo g Box for a Two-Sided Wall 9.For two-w ay FSI simula tions , define d ynamic mesh pr operties t o allo w the mesh t o handle the def ormation of the solid z one .This includes the f ollowing: •Enable d ynamic mesh Smoothing , and selec t either the Diffusion or Linear ly E lastic S olid metho d in the Mesh M etho d Settings D ialog Box (p.3570 ). •For cases with str ong FSI c oupling (such as when the fluid and solid densities ar e compar able), enable the Implicit U pdate option in the Dynamic M esh task page and define appr opriate settings in the Im- plicit U pdate tab of the Options dialo g box. For details , see Setting D ynamic M esh M odeling P aramet- ers (p.1266 ) and Implicit U pdate Settings (p.1332 ). •Define an Intrinsic FSI dynamic mesh z one f or the side of a t wo-sided w all (tha t is, the w all or w all- shado w) tha t is immedia tely adjac ent to the fluid c ell z one (as indic ated b y the Adjac ent Cell Z one field in the Wall dialo g box). For fur ther details , see Intrinsic FSI M otion (p.1362 ). Setup → Dynamic M esh 10.For tr ansien t simula tions , you c an mak e a selec tion fr om the Structure Transien t Formula tion drop-do wn list in the Solution M etho ds Task P age (p.3603 ) to sp ecify the dir ect time in tegration metho d used t o solv e the finit e elemen t semi-discr ete equa tion of motion. You c an selec t from the Newmar k metho d (default) or the Back ward Euler metho d. For fur ther details ab out these metho ds, see Dynamic S tructural Systems in the Theor y Guide . Solution → Metho ds 11.You c an r evise the f ollowing settings if y ou find tha t the defaults do not pr oduce sa tisfac tory results: •You c an sp ecify the solution metho d used b y the linear solv er for the str uctural mo del c alcula tions . By default , the bi-c onjuga te gr adien t stabiliz ed (BC GSTAB) metho d is used .This metho d off ers a go od balanc e of sp eed and r obustness . If div ergenc e is det ected with BC GSTAB, then the gener alized minimal r esidual (GMRES) metho d will b e used f or an it eration as a fallback, and y ou will b e inf ormed in the c onsole tha t 2333Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p an In trinsic F luid-S tructure Interaction (FSI) S imula tiona "fe-str ucture" equa tion is b eing stabiliz ed t o enhanc e linear solv er robustness . If you find tha t your residual le vel / dr op is not sa tisfac tory, you c an tr y incr easing the maximum numb er of inner it erations from the default of 500 b y using the f ollowing t ext command: define → models → structure → controls → max-iter If the BC GSTAB metho d continues t o pr oduce unsa tisfac tory residuals with a higher numb er of inner it erations or if y ou r epeatedly see c onsole messages tha t say the GMRES fallback is b eing used , you c an change the solution t o the GMRES metho d. Note tha t GMRES is the most r obust metho d, but it is also mor e demanding in t erms of memor y usage and solv er time .With GMRES, it is r ecommended tha t you star t with the maximum it erations set t o 50. Also a vailable is the conjuga te gr adien t (CG) metho d: while in some c ases it is the least r obust metho d, it c an r esult in fast er calcula tions , as it tak es ad vantage of the symmetr y of the ma trix used in the linear sy stems of equa tions .To change the solution metho d, use the f ollowing t ext command: define → models → structure → controls → amg-stabilization •For tr ansien t simula tions , you c an r evise the numer ical damping fac tor for the str uctural mo del c alcula tions (tha t is, the amplitude dec ay fac tor in Equa tion 21.14 in the Theor y Guide ) by using the f ollowing t ext command: define → models → structure → controls → numerical-damping-factor? •You c an enable an e xplicit fluid-str ucture interaction f orce by using the f ollowing t ext command: define → models → structure → expert → explicit-fsi-force? •You c an enable the inclusion of op erating pr essur e into the fluid-str ucture interaction f orce by using the f ollowing t ext command: define → models → structure → expert → include-pop-in-fsi-force? •You c an enable the inclusion of a visc ous fluid-str ucture interaction f orce by using the f ollowing t ext command: define → models → structure → expert → include-viscous-fsi-force? 12.If nec essar y, revise the default c onvergenc e criteria for the x-y-, and (f or 3D c ases) z-displac emen t residual equa tions in the Residual M onit ors D ialog Box (p.3910 ). Solution → Monit ors → Residual Edit... 13.(Optional) C reate str uctural p oint sur faces a t points of in terest within the solid z one , which y ou c an use f or monit oring and r eporting da ta. Note tha t for two-w ay FSI simula tions , a str uctural p oint surface do es not nec essar ily remain fix ed in spac e, but will c ontinue t o represen t its or iginal c ell as the solid z one mo ves / def orms. Results → Surfaces New → Structural P oint... For fur ther details , see Structural Point Sur faces (p.2737 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2334Modeling F luid-S tructure Interaction (FSI) Within F luen tTo monit or a field v ariable a t such a str uctural p oint sur face, create a r eport definition. For e xample , you c ould monit or and plot the v ertex average of the displac emen t of the no des tha t sur round a structural p oint sur face: Solution → Rep ort Definitions New → Surface Rep ort → Vertex Average ... For fur ther details , see Creating R eport Definitions (p.2910 ). 14.Initializ e the solution. Note tha t for standar d initializa tion, you c an sp ecify the initial X,Y, and (f or 3D c ases) Z Displac emen t in the Solution Initializa tion Task P age (p.3620 ). Solution → Initializa tion 15.Run the c alcula tion. Solution → Run C alcula tion Tip For one-w ay FSI simula tions , the c alcula tion time will b e fast er if y ou first r un the c alcu- lation with only the fluid equa tions enabled in the Equa tions dialo g box, and then r un it with only the str ucture equa tion enabled . Solution → Controls Equa tions ... 16.View the r esults b y displa ying c ontours of the f ollowing field v ariables (in the Structure... categor y): •X,Y, and Z Displac emen t for the displac emen t values •Sigma X X,YY,XY,ZZ,YZ, and XZ for the str ess t ensor v alues Results → Graphics → Contours New... Note You should c onfir m tha t the str ess loading do es not e xceed the yield str ength of the solid ma terial, as this is an assumption of the Linear E lasticit y structural mo del. 2335Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting U p an In trinsic F luid-S tructure Interaction (FSI) S imula tionRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2336Chapt er 30: Modeling E uler ian Wall F ilms The E uler ian Wall F ilm (E WF) mo del c an b e used t o pr edic t the cr eation and flo w of thin liquid films on the sur face of w alls.This chapt er pr esen ts inf ormation ab out the basic func tionalit y of the E uler ian Wall Film (E WF) mo del. Additional inf ormation ab out the mo del is pr ovided in the f ollowing sec tions: 30.1. Limita tions 30.2. Setting E uler ian Wall F ilm M odel Options 30.3. Setting E uler ian Wall F ilm S olution C ontrols 30.4. Setting E uler ian Wall F ilm B oundar y, Initial, and S ource Term C onditions 30.5. Postpr ocessing the E uler ian Wall F ilm For mor e inf ormation ab out E uler ian Wall F ilm mo del theor y, see Euler ian Wall F ilms in the Theor y Guide (p.1). For mor e inf ormation ab out setting b oundar y conditions f or liquid films a t wall b oundar ies, see Wall F ilm C onditions f or Walls (p.994). 30.1. Limita tions The f ollowing limita tions e xist f or the E uler ian Wall F ilm mo del: •The E uler ian Wall F ilm mo del is a vailable f or 3D geometr ies only . •Many mo dels (f or e xample ,VOF multiphase flo w or r adia tion) will not in teract correctly with the film mo del without first mo difying the b oundar y conditions using UDFs . •Wallfilm b ehavior a t junc tions with baffles (z ero-thick ness w alls) ma y lead t o unph ysical results due t o the local mesh t opology (w all, wall-shado w) and should b e used with c are, tha t is, isola ted film w alls must not shar e a c ommon edge . •The w all film c an only b e single-c omp onen t, but not multi-c omp onen t. •The E uler ian Wall F ilm mo del is not c ompa tible with non-c onformal in terfaces. •The E uler ian Wall F ilm mo del is not c ompa tible with mesh op erations in F luen t (such as mesh adaption, cell separ ation, face zone e xtrusion, and c ell z one t ype change). 30.2. Setting E uler ian Wall F ilm M odel Options You c an enable the E uler ian Wall F ilm mo del b y selec ting Euler ian Wall F ilm from the Models task page . Setup → Models → Euler ian Wall F ilm Edit... This op ens the Eulerian Wall F ilm dialo g box. 2337Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Onc e you op en the Euler ian Wall F ilm D ialog Box (p.3379 ), you c an selec t the Euler ian Wall F ilm check box to enable the mo del so tha t you c an use it in y our simula tion. Enabling the mo del e xpands the dialo g box to reveal additional mo del options and solution c ontrols. Imp ortant If you w ant to mo dify y our mesh in F luen t, you must first disable the E uler ian Wall F ilm model. Onc e you sa ve the mo dified mesh, you must r e-enable the E uler ian Wall F ilm mo del and r e-initializ e your c ase. You c an set gener al Euler ian Wall F ilm mo del options in the Model Options and S etup tab of the Eu- lerian Wall F ilm dialo g box.This tab c ontains c ontrols f or sp ecific solution, discr ete phase mo del (DPM), and ma terial options f or the E uler ian Wall F ilm mo del. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2338Modeling E uler ian Wall F ilmsIn the Model Options and S etup tab , the f ollowing options and c ontrols ar e available: Solve M omen tum specifies whether the momen tum equa tion (see Equa tion 22.2 in the Fluent Theor y Guide ) is solv ed f or the wall film or not. In the Momen tum Options group b ox, you c an individually selec t each t erm of the equa tion f or inclusion in the c alcula tions . Note tha t Spreading Term and Surface Tension under Momen tum Options are available only when Pressur e Gradien t is selec ted. Solve Energy specifies whether the ener gy equa tion (see Equa tion 22.3 in the Fluent Theor y Guide ) is solv ed f or the w all film or not. 2339Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting E uler ian Wall F ilm M odel OptionsSolve Sc alar specifies whether the passiv e sc alar tr ansp ort equa tion Equa tion 22.38 is solv ed f or the w all film or not. When the Solve Sc alar option is enabled , you c an sp ecify Scalar D iffusivit y. DPM C ollec tion includes discr ete phase par ticles and their in teraction with the film mo del (see DPM C ollec tion in the Fluent Theor y Guide ).You c an selec t: •Particle S plashing You c an sp ecify splashing options in the Wall F ilm tab of the Wall dialo g box. For details , see Setting E uler ian Wall F ilm B oundar y, Initial, and S ource Term C onditions (p.2344 ). •Particle S tripping and sp ecify the settings under the Stripping Options group b ox (for details , see Film S epar ation in the Fluent Theor y Guide ) •Edge S epar ation and sp ecify the settings under the Separ ation Options group b ox (for details , see Film S epar ation in the Fluent Theor y Guide ) Note tha t Random S epar ation means tha t the lo cations a t which the newly spa wned par ticles are injec ted (due t o film separ ation) ar e randomly selec ted along the edge a t which the separ ation takes plac e. Treat Sharp Edge accoun ts for the eff ects of shar p edges and sp ecify Sharp Edge A ngle .When the Treat Sharp Edge option is enabled and wher e the edge angle is smaller than the Sharp Edge A ngle , the film w all edge is tr eated as a b oundar y edge (namely , the film b ecomes detached fr om the w all, rather than b ending ar ound the edge and a ttaching t o the w all). If the D iscrete Phase M odel has b een enabled along with the E uler ian Wall F ilm mo del, then the film w all edge is tr eated as a separ ation edge . Phase A ccretion accoun ts for the eff ect of the in teraction of the w all film with E uler ian and M ixture multiphase flo w (see Secondar y Phase A ccretion in the Fluent Theor y Guide ).This option enables y ou t o comput e the sec ondar y phase c ollec tion efficienc y on a w all sur face.This option is only a vailable when the E uler ian or M ixture (with S lip Velocity) M ultiphase mo del is enabled . Note The f ollowing c onsider ations should b e tak en in to acc oun t when the E uler ian Wall F ilm model is used with the E uler ian or M ixture multiphase mo dels: •You must cr eate temp orary plac eholder injec tions in or der t o mo del edge separ ation and edge str ipping . •The ma terial pr operties f or the sec ondar y phase should b e the same as the DPM particles . •The name of the sec ondar y phase ma terial should b e included in the name of the DPM particle ’s ma terial and should b e app ended with the str ing ‘-par ticle ’ (for e xample , if the sec ondar y phase ma terial name is waterliquid- euler ian, then the DPM par ticle ’s material name should b e waterliquid-euler ian-par ticle ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2340Modeling E uler ian Wall F ilmsPhase C hange accoun ts for phase changes b etween the film ma terial (liquid) and the gas sp ecies (v apor) (see Coupling of Wall F ilm with M ixture Species Transp ort in the Fluent Theor y Guide ).This option enables y ou t o set the following: •Film Vapor M aterial—in the Material Options group b ox. •Phase change par amet ers—in the Wall F ilm tab of the Wall dialo g box. For details , see Setting E uler ian Wall F ilm B oundar y, Initial, and S ource Term C onditions (p.2344 ). Note The liquid film c an only b e a single-c omp onen t fluid .The sec ondar y phase tha t is in tended for the film ma terial c annot b e a mix ture of sp ecies . Material Options allow to selec t film ma terial and film v apour ma terial (a vailable only f or P hase C hange c alcula tions) and specify w all film sur face tension. Note The t ype of ma terial for a w all film must b e Fluid ,Droplet P article , or Iner t Particle (fluid). You c an define densit y, visc osity, specific hea t, ther mal c onduc tivit y, vaporization t em- perature, and v apor sa turation pr essur e of a w all film ma terial or film v apor using one of the f ollowing metho ds: •constan t •polynomial (including piec ewise linear and piec ewise p olynomial) •compr essible liquid (f or fluid densit y) •user-defined (not a vailable f or fluid sp ecific hea t) •default-metho d (for film v apor sa turation pr essur e) Solve Wall F ilm enables y ou t o sk ip the w all film solution dur ing the gas phase solution, but k eep the v ariables and setup active. Note The w all film c annot b e solv ed without first initializing the w all film mo del (using the Initializ e butt on) t o initializ e the w all film v ariables and pr epar e the solv er for the solution pr ocedur e. You c an also use the define/models/eulerian-wallfilm/model-options text command t o define the settings and the discr etiza tion metho ds for the E uler ian Wall F ilm mo del. 2341Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting E uler ian Wall F ilm M odel Options30.3. Setting E uler ian Wall F ilm S olution C ontrols You c an set solution c ontrols f or the E uler ian Wall F ilm mo del in the Solution M etho d and C ontrol tab of the Euler ian Wall F ilm dialo g box.This tab c ontains c ontrols f or sp ecific t emp oral and spa tial discr etiza tion options f or the E uler ian Wall F ilm mo del. Figur e 30.1: Euler ian Wall F ilm S olution C ontrols (S tead y Flow) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2342Modeling E uler ian Wall F ilmsFigur e 30.2: Euler ian Wall F ilm S olution C ontrols (U nstead y Flow) In the Solution M etho d and C ontrol tab , you c an set the f ollowing: •Temp oral and spa tial (c ontinuit y, momen tum, ener gy, and passiv e sc alar) discr etiza tion metho ds under Discr etiza tion . •Maximum Thick ness for the film. The Maximum Thick ness setting will limit the film thick ness b y remo ving ma terial fr om the film wher e this v alue is e xceeded . 2343Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting E uler ian Wall F ilm S olution C ontrols•For st eady sta te calcula tions ( Figur e 30.1: Euler ian Wall F ilm S olution C ontrols (S teady Flow) (p.2342 )): You c an sp ecify the film mo del sp ecific Time S tep (the E uler ian Wall F ilm mo del is alw ays tran- sien t), or y ou c an selec t the Adaptiv e Time S tepping option t o set the Max. Cour ant Numb er and the Initial Time S tep (see Steady Flow). •For tr ansien t cases ( Figur e 30.2: Euler ian Wall F ilm S olution C ontrols (U nsteady Flow) (p.2343 ): You c an define the Numb er of Time S teps per main flo w time st ep and the Sub-T ime Rep ort Interval for film c alcula tion r eporting . Note tha t the first and the last sub-time st eps ar e alw ays reported. •For either first or sec ond or der implicit time discr etiza tion c alcula tions: You c an c ontrol the numb er of film Sub-I terations , the v alue of Sub-I teration S top below which the film sub-it eration st ops, and the Sub-I ter Rep ort In terval for film sub-it eration r eporting . Note tha t the first and the last sub-it erations ar e alw ays reported. •If DPM C ollec tions is selec ted in the Model Options and S etup tab: You c an set ho w of ten the DPM phase is c alcula ted f or the film b y sp ecifying a v alue f or the Film S teps p er DPM S tepThese c ontrols ar e only a vailable if Interaction with C ontinuous Phase is disabled in the Discr ete Phase M odel dialo g box. 30.4. Setting E uler ian Wall F ilm B oundar y, Initial, and S our ce Term C on- ditions In the Wall dialo g box, under the Wall F ilm tab , you c an set b oundar y, initial, and sour ce term conditions for liquid films on sp ecified w all b oundar ies.When y ou selec t the Euler ian F ilm Wall option, Fluen t solv er designa tes the w all as a film w all.Wall film equa tions ar e only solv ed on designa ted film w alls. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2344Modeling E uler ian Wall F ilmsFigur e 30.3: Wall D ialo g Box (Initial C onditions) The f ollowing t ypes of film c onditions e xist in ANSY S Fluen t: •Boundar y Condition : Is wher e film mass , momen tum, ener gy and sc alar quan tities ar e introduced t o the wall film solution domain. You c an en ter v alues f or the f ollowing quan tities: 2345Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting E uler ian Wall F ilm B oundar y, Initial, and S ource Term C onditions–Film M ass F lux –X-M omen tum F lux,Y-M omen tum F lux, and Z-M omen tum F lux –Incoming F ilm Temp erature –Film P assiv e Sc alar F lux For mo ving w all simula tions , you c an sp ecify the film momen tum flux r elative to the w all on which liquid film is defined b y selec ting Rela tive Film M omen tum F lux. Note tha t this option is only available when Moving Wall is selec ted in the Wall dialo g box and/or Frame M otion is selec ted in the Fluid dialo g box. the film momen tum flux or initial v elocity inputs will b e relative to the w all on which liquid film is defined . •Initial C ondition : Is the initial sta te of w all film. You c an set v alues f or the f ollowing quan tities: –Film H eigh t –X-V elocity,Y-V elocity, and Z-Velocity comp onen ts –Film Temp erature –Film P assiv e Sc alar For mo ving w all simula tions , you c an sp ecify the initial v elocity relative to the w all on which liquid film is defined b y selec ting Rela tive Initial F ilm Velocity. Note tha t this option is only a vailable when Moving Wall is selec ted in the Wall dialo g box and/or Frame M otion is selec ted in the Fluid dialo g box. If you selec t the User S our ce Terms option (a vailable only with initial c ondition), you c an also sp ecify additional sour ce terms t o the film c ontinuit y, momen tum, ener gy, and passiv e sc alar equa tions b y setting v alues f or the f ollowing quan tities: –Mass F lux –X-M omen tum F lux,Y-M omen tum F lux, and Z-M omen tum F lux –Heat Flux –Scalar F lux For b oth b oundar y and initial c onditions , if y ou selec t the Flow M omen tum C oupling option, the liquid film and the gas flo w shar es the same v elocity at the in terface of the liquid-gas in terface using a t wo- way coupling . If you clear this option, the c oupling b etween the liquid film and the gas flo w o ccurs only one-w ay, namely , while the gas flo w impac ts the film flo w, the film flo w do es not impac t the bulk of the gas flo w. When the Phase C hange option is selec ted in the Euler ian Wall F ilm dialo g box, you c an enable the Film P hase C hange for the selec ted film w all, and then selec t the Phase C hange M odel and sp ecify the mo del par amet ers.The f ollowing phase change mo dels ar e available: •diffusion-balanc e Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2346Modeling E uler ian Wall F ilmsFor the diffusion-balanc e mo del, you c an sp ecify Condensa tion C onstan t and Vaporization C on- stan t. •wall-b oundar y-la yer No user input is r equir ed f or this mo del. •user-defined For the user-defined mo del, you c an sp ecify Condensa tion R ate and Vaporization R ate as c onstan ts, paramet ers, or pr ofile user-defined func tions (UDFs). Note tha t condensa tion and v aporization r ates must b e sp ecified as p ositiv e values in k g/s. For mor e inf ormation on pr ofile UDFs , the separ ate Fluen t Customiza tion M anual . For mor e inf ormation on the phase change mo dels see Coupling of Wall F ilm with M ixture Species Transp ort in the Fluent Theor y Guide . For c ases with initial c ondition, if y ou selec t the Surface Tension option in the Euler ian Wall F ilm dialo g box, then y ou c an enable the P artial Wetting mo del f or the selec ted film w all b y selec ting the Film C ontact Angle option. You c an then sp ecify the f ollowing par amet ers in the Contact Angle Paramet ers group b ox: •Mean Contact Angle ( in Partial Wetting E ffect in the Fluent Theor y Guide ) The input r ange f or the mean Contact Angle is 0 t o 180 degr ees.You c an also use a user-defined profile UDF .The UDF must r etur n a c ontact angle v alue within the ab ove range in r adian. For mor e information on pr ofile UDFs , the separ ate Fluen t Customiza tion M anual . •Rela tive Standar d D eviation ( in Partial Wetting E ffect in the Fluent Theor y Guide ) The input f or the Rela tive Standar d D eviation should b e in the r ange of 0 t o 50%. •Contact Angle F orce Beta ( in Equa tion 22.29 in the Fluent Theor y Guide ) The input r ange f or Contact Angle F orce Beta is 0 t o 10. For mor e inf ormation on mo delling film par tial w etting eff ect see Partial Wetting E ffect in the Fluent Theor y Guide . When the DPM C ollec tion option is selec ted in the Euler ian Wall F ilm dialo g box, you c an selec t a particle-w all impingemen t mo del and sp ecify r elevant mo del par amet ers in the Wall dialo g box.The following impingemen t mo dels ar e available in ANSY S Fluen t: •stanton-rutland (see The S tanton-R utland M odel in the Fluent Theor y Guide for details) •kuhnke (see The K uhnk e Model in the Fluent Theor y Guide for details) For the K uhnk e mo del, you must sp ecify the f ollowing mo del par amet ers: –Ra:The w all mean r oughness tha t is used t o comput e in Equa tion 16.268 in the Fluent Theor y Guide –Rz:The a verage sur face roughness tha t is used t o comput e splashed par ticle r eflec tion angle distr ibution Equa tion 16.280 in the Fluent Theor y Guide . 2347Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting E uler ian Wall F ilm B oundar y, Initial, and S ource Term C onditions–Critical Temp erature Factor:The dimensionless v ariable tha t is used t o det ermine the impingemen t regime tr ansition t emp erature in Equa tion 16.260 in the Fluent Theor y Guide . Note You c an also add an impingemen t eff ect via UDFs as descr ibed in Hooking DEFINE_IM- PINGEMENT UDFs ,Hooking DEFINE_FILM_REGIME UDFs , and Hooking DEFINE_SPLASHING_DISTRIBUTION UDFs in the Fluent C ustomization Manual . Note tha t UDFs settings will o verride those f or the impingemen t/splashing mo del selec ted f or the E u- lerian w all film b oundar y condition. In addition, when Particle S plashing is selec ted in the Euler ian Wall F ilm dialo g box, you c an selec t DPM Wall S plash and sp ecify Numb er of S plashed P articles . 30.5. Postpr ocessing the E uler ian Wall F ilm When using the E uler ian Wall F ilm mo del, the f ollowing additional v ariables will b e available f or p ost- processing (see Field F unction D efinitions (p.2959 ) for their definitions): •Film Thick ness •Film M ass •Film Temp erature (when Solve Energy is enabled) •Film X-V elocity •Film Y-V elocity •Film Z-V elocity •Film Velocity M agnitude •Film S urface X-V elocity •Film S urface Y-V elocity •Film S urface Z-V elocity •Film S urface Velocity M agnitude •Film S urface Temp erature (when Solve Energy is enabled) •Film P assiv e Sc alar (when Solve Sc alar is enabled) •Film D ensit y (when film ma terial densit y is non-c onstan t) •Film E ffective Pressur e •Film C overage (when Solve M omen tum is enabled) •Film C our ant Numb er •Film Weber N umb er Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2348Modeling E uler ian Wall F ilms•Film S tripped M ass (when Particle S tripping is enabled) •Film S tripped D iam (when Particle S tripping is enabled) •Film DPM M ass S our ce (when DPM C ollec tion is enabled) •Film DPM E nergy Sour ce (when DPM C ollec tion and Solve Energy are enabled) •Film DPM X-M omen tum S our ce (when DPM C ollec tion is enabled) •Film DPM Y-M omen tum S our ce (when DPM C ollec tion is enabled) •Film DPM Z-M omen tum S our ce (when DPM C ollec tion is enabled) •Film S epar ated M ass (when Edge S epar ation is enabled) •Film S epar ated D iam (when Edge S epar ation is enabled) •Film S epar ation R ate (when Edge S epar ation is enabled) •Film P hase C hange R ate (when Phase C hange is enabled) •Film Outflo w M ass •Film S econdar y Phase M ass (when Phase A ccretion is enabled) •Film S econdar y Phase C ollec tion C oef (when Phase A ccretion is enabled) You c an r eport on the mass and ener gy flux es for the E uler ian Wall F ilm mo del using the Flux Rep orts dialo g box (see Gener ating a F lux R eport (p.2937 )), for domain b oundar ies such as inlets , outlets , and so on, as w ell as w all b oundar ies. Results → Rep orts → Fluxes Edit... The Film M ass F low R ate and Film H eat Transf er R ate are available as options in the Flux Rep orts dialo g box when the Euler ian Wall F ilm mo del is enabled . Note The ener gy flux r eport only acc oun ts for the hea t transf er rate thr ough the e xternal b oundar y. It do es not c onsider hea t transf er a t gas-liquid in terfaces or hea t transf er due t o phase change or film-DPM in teraction. You c an also r eport on the mass flo w rate and hea t transf er rate using the U ser In terface (TUI) as f ollows: •For mass flo w rate, enter the t ext command report/fluxes/film-mass-flow . •For hea t transf er r ate, enter the t ext command report/fluxes/film-heat-transfer . You will b e pr ompt ed f or the b oundar y fac e zone IDs f or which the r eport will b e gener ated, and whether or not y ou w ant to sa ve the r eported v alues t o a file . ANSY S Fluen t will either pr int the r eport in the c onsole or wr ite it t o the file y ou ha ve sp ecified . 2349Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Postpr ocessing the E uler ian Wall F ilmRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2350Chapt er 31: Modeling E lectric Potential F ield This chapt er pr ovides details ab out ho w to mo del and simula te the elec tric potential field in ANSY S Fluen t.The theor etical asp ects of the elec tric potential mo del ar e pr esen ted in Electric Potential in the Fluent Theor y Guide . Additional inf ormation ab out the mo del is pr ovided in the f ollowing sec tions: 31.1. Overview and Limita tions 31.2. Using the E lectric Potential M odel 31.3. Postpr ocessing the E lectric Potential F ield 31.1. Overview and Limita tions The ANSY S Fluen t elec tric potential mo del allo ws for pr edic ting the elec tric potential field and its eff ects. The elec tric potential mo del c an b e used separ ately (f or e xample , to comput e elec tric sta tic f orce for char ged par ticles in a DPM c alcula tion) or in c ombina tion with other ANSY S Fluen t mo dels . The elec tric potential solv er has b een in tegrated with the elec trochemic al reaction mo del ( Electrochem- ical Reactions in the Fluent Theor y Guide ).When y ou enable the elec trochemistr y in y our c ase, ANSY S Fluen t aut oma tically enables the elec tric potential solv er. However, if y ou w ant to use the elec tric po- tential mo del along with other ANSY S Fluen t mo dels , you need t o manually enable it as descr ibed in Using the E lectric Potential M odel (p.2351 ). Using the elec tric potential solv er, you c an simula te the elec tric potential field in b oth fluid and solid zones . When defining the b oundar y conditions f or the elec tric potential field , you c an sp ecify either p otential or cur rent densit y at the e xternal w alls. The f ollowing limita tion e xist f or the elec tric potential mo del: •The elec tric potential mo del c annot b e used in simula tions with w alls tha t ha ve a shell c onduc tion b oundar y condition. 31.2. Using the E lectric Potential M odel The pr ocedur e for setting up the elec tric potential mo del is descr ibed b elow. Note tha t only st eps tha t are pertinen t to elec tric potential field mo deling ar e list ed her e.You will also need t o define the other settings (such as other ma terial pr operties, boundar y conditions , other mo dels) as usual. For inf ormation about inputs r elated t o other ANSY S Fluen t mo dels tha t you ar e using in c onjunc tion with the elec tric potential mo del, refer to the appr opriate sec tions f or those mo dels . 1.In the Potential dialo g box, which is op ened fr om the Model/Electric P otential tree it em, enable the Potential E qua tion option. 2351Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Onc e the Potential E qua tion is enabled , the elec tric conduc tivit y ma terial pr operty for fluid , solid , and mix ture ma terials defined in y our c ase will app ear in the Create/Edit M aterials dialo g box. 2.If you w ant to include J oule hea ting in the ener gy equa tion ( Equa tion 5.1 in the Fluent Theor y Guide ), under the Model Option group b ox, enable Include J oule H eating in E nergy Equa tion . Note The Include J oule H eating in E nergy Equa tion option app ears in the Potential dialo g box only when Energy Equa tion is enabled in the Energy dialo g box. 3.In the Create/Edit M aterials dialo g box, under Properties , specify Electric C onduc tivit y for the c onduc tive materials defined in y our simula tion. Setup → Materials 4.Define b oundar y conditions on c onduc tive external w alls. Setup → Boundar y Conditions Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2352Modeling E lectric Potential F ieldFor one-sided w alls, you c an sp ecify the f ollowing c onditions a t the b oundar y wall: •Contact Resistanc e: is in Equa tion 23.3 in the Fluent Theor y Guide •One of the f ollowing p otential b oundar y conditions: –Current Densit y (if Specified F lux is selec ted fr om the Potential B oundar y Condition drop-do wn list) –Potential (if Specified Value is selec ted fr om the Potential B oundar y Condition drop-do wn list) For two-sided in ternal w alls, the c oupled b oundar y treatmen t is alw ays applied t o wall and w all- shado w pairs . In addition, you c an apply c ontact resistanc e to in ternal w alls. Note tha t you only need t o define Contact Resistanc e on one of the w alls.The v alue y ou sp ecify on one w all will b e automa tically c opied t o another w all. 5.If requir ed, specify elec tric potential c onditions on other b oundar ies in the Potential tab of the b oundar y conditions dialo g boxes. Note tha t the default setting , zero cur rent flux, is suitable f or most pr oblems and needs not b e changed . 6.If you w ant to fix a v alue of p otential or sp ecify a p otential sour ce in a c ell z one , you c an do it b y setting the Fixed Values or Sour ce Terms in the appr opriate cell z one c ondition dialo g box. 31.3. Postpr ocessing the E lectric Potential F ield For p otential field c alcula tions , you c an gener ate gr aphic al plots or alphanumer ic reports of the f ollowing items (see Field F unction D efinitions (p.2959 ) for their definitions). These quan tities ar e available in the variable selec tion dr op-do wn lists tha t app ear in p ostpr ocessing dialo g boxes: •Electric P otential (in the Potential... categor y) •Electric C onduc tivit y (in the Properties ... categor y) •Current Magnitude (in the Potential... categor y) •Joule H eat Sour ce (in the Potential... categor y) You c an also gener ate vector plots of the elec tric cur rent fields b y selec ting Electric C urrent in the Vectors of drop-do wn list in Vectors D ialog Box (p.3954 ). 2353Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Postpr ocessing the E lectric Potential F ieldRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2354Chapt er 32: Modeling B atteries This chapt er pr ovides inf ormation ab out using the ba ttery mo dels a vailable in ANSY S Fluen t. Additional information ab out the mo del is pr ovided in the f ollowing sec tions: 32.1. Introduction 32.2. Using the S ingle-P otential Empir ical Battery Model 32.3. Using the D ual-P otential MSMD and C ell N etwork Battery Models 32.1. Introduc tion The applic ation of lithium ion ba tteries has b een r apidly e xpanding fr om elec tric applianc es and elec- tronic de vices to hybrid elec tric vehicles (HE Vs) and elec tric vehicles (E Vs), due t o their high ener gy densit y.The main c oncerns when designing a Li-ion ba ttery are its p erformanc e, life, and saf ety.The ANSY S Fluen t ba ttery mo dels allo w simula ting a single ba ttery cell or a ba ttery pack using CFD t echnolo gy to stud y their ther mal and elec trochemic al b ehavior.The ANSY S Fluen t ba ttery mo dels ar e pr ovided as add-on mo dules with the standar d ANSY S Fluen t licensed sof tware. Note tha t the F luen t Tutorials pr ovides tut orials tha t illustr ate ho w to use the ANSY S Fluen t ba ttery models . This chapt er contains the f ollowing inf ormation: 32.1.1. Overview 32.1.2. Gener al Procedur e 32.1.3. Installing the B attery Module 32.1.1. Overview In a lithium-ion ba ttery, the ano de and c athode ar e made of ac tive ma terials c oated on the sur face of metal f oils. A p olymer separ ator is plac ed b etween the f oils of opp osite polar ity to pr event elec trons from passing b etween them. To pr edic t the e volution of the chemic al, ther mal, and elec trical pr ocesses in a ba ttery, ANSY S Fluen t off ers the f ollowing mo dels: •Using the S ingle-P otential Empir ical Battery Model (p.2357 ) •Using the D ual-P otential MSMD and C ell N etwork Battery Models (p.2368 ) The S ingle-P otential Empir ical Battery Model is useful if the geometr ies of the cur rent collec tor, elec- trodes, and separ ator c an b e fully r esolv ed. One p otential equa tion is solv ed in the c omputa tional domain. This mo del is b est suit ed f or elec trode-sc ale pr edic tions in a single ba ttery cell. The mo del, however, has a limit ed abilit y to stud y the full r ange of elec trochemic al phenomena in battery sy stems , esp ecially sy stems ha ving c omple x geometr y.When c onstr ucting a ba ttery cell, the ano de-separ ator-c athode sand wich la yer is usually w ound or stack ed up in to a 'jelly r oll' or a pr isma tic shap e. It would b e very expensiv e to resolv e all the la yers e xplicitly , even f or a single ba ttery cell. Further mor e, man y industr ial applic ations use a ba ttery pack c onsisting of a lar ge numb er of c ells connec ted in ser ies or in par allel. 2355Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.The ANSY S Fluen t Dual P otential M ulti-Sc ale M ulti-D imensional (MSMD) B attery mo del o vercomes these limita tions b y using a homo geneous mo del based on a multi-sc ale multi-dimensional appr oach. In this appr oach, the whole ba ttery is tr eated as an or thotr opic c ontinuum; thus , the mesh is no longer constr ained b y the micr o-str ucture of the ba ttery.Two potential equa tions ar e solv ed in the ba ttery domain. To fit v arious analy sis needs , the mo del includes thr ee elec trochemic al submo dels , namely , the N ewman, Tiedemann, Gu, and K im (NT GK) empir ical mo del, the E quiv alen t Circuit mo del (ECM), and the N ewman ’s Pseudo-2D (P2D) mo del ha ving diff erent level of c omple xity.The mo del off ers y ou the fle xibilit y to stud y the ph ysical and elec trochemic al phenomena tha t extend o ver man y length scales in ba ttery sy stems of v arious ar rangemen ts. 32.1.2. Gener al P rocedur e The f ollowing descr ibes an o verview of the pr ocedur e requir ed in or der t o use the B attery Model in ANSY S Fluen t. 1.Start ANSY S Fluen t. 2.Read the mesh file . 3.Scale the gr id, if nec essar y. 4.Load the mo dule and use the Battery M odel dialo g box to define the ba ttery mo del par amet ers. 5.Define ma terial pr operties. 6.Set the op erating c onditions . 7.Set the b oundar y conditions . 8.Start the c alcula tions . 9.Save the c ase and da ta files . 10.Process y our r esults . Imp ortant Note tha t the major ity of this manual descr ibes ho w to set up the ANSY S Fluen t Battery Model using the gr aphic al user in terface.You c an also p erform v arious tasks using the t ext user in terface. 32.1.3. Installing the B attery M odule The ba ttery add-on mo dules ar e installed with the standar d installa tion of ANSY S Fluen t in a dir ectories called addons/battery (for the single-p otential empir ical ba ttery mo dule) and addons/msmdbatt (for the dual-p otential MSMD ba ttery mo del) in y our installa tion ar ea.The ba ttery mo dules c onsist of UDF libr aries and pr e-compiled scheme libr aries tha t need t o be loaded and ac tivated b efore calcula tions can b e performed . A numb er of UDFs ar e used t o solv e the ba ttery equa tions . Onc e you loaded the battery add-on mo dule , UDF and scheme libr aries tha t are requir ed b y the ba ttery mo del ar e aut omat- ically loaded . Further details ar e pr ovided in chapt ers tha t descr ibes the mo dels . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2356Modeling B atteries32.2. Using the S ingle-P otential E mpir ical B attery M odel The pr ocedur e for setting up and solving the S ingle-P otential Empir ical ba ttery mo del is descr ibed in detail in this sec tion. Refer to Single-P otential Empir ical Battery Model Theor yfor inf ormation ab out the theor y. 32.2.1. Geometr y Definition f or the S ingle-P otential Empir ical Battery Model 32.2.2. Loading the S ingle-P otential Empir ical Battery Module 32.2.3. Getting S tarted With the S ingle-P otential Empir ical Battery Model 32.2.4. Solution C ontrols f or the S ingle-P otential Empir ical Battery Model 32.2.5. Postpr ocessing the S ingle-P otential Empir ical Battery Model 32.2.6. User-A ccessible F unctions For inf ormation ab out inputs r elated t o other mo dels used in c onjunc tion with the ba ttery mo del, see the appr opriate sec tions f or those mo dels in the ANSY S Fluen t Fluen t User's G uide (p.1). 32.2.1. Geometr y Definition f or the S ingle-P otential E mpir ical B attery Model Due t o the fac t tha t ther e ar e a numb er of diff erent ph ysical zones asso ciated with the ba ttery cell, the f ollowing r egions must b e pr esen t in the ba ttery mesh: •Anode •Cathode •Separ ator (‘ zero’ thick ness w all/w all-shado w in terface) Note For elec tro-chemic al types of simula tion, 3D double-pr ecision is r ecommended . 32.2.2. Loading the S ingle-P otential E mpir ical B attery M odule The single-p otential empir ical ba ttery add-on mo dule is installed with the standar d installa tion of ANSY S Fluen t in a dir ectory called addons/battery in y our installa tion ar ea.The ba ttery mo dule consists of a UDF libr ary and a pr e-compiled Scheme libr ary, which need t o be loaded and ac tivated before calcula tions c an b e performed . The ba ttery mo dule is loaded in to ANSY S Fluen t thr ough the t ext user in terface (TUI). The mo dule c an be loaded only when a v alid ANSY S Fluen t case file has b een set or r ead.The t ext command t o load the mo dule is define → models → addon-module A list of ANSY S Fluen t add-on mo dules is displa yed: Fluent Addon Modules: 0. none 1. MHD Model 2. Fiber Model 3. Fuel Cell and Electrolysis Model 4. SOFC Model with Unresolved Electrolyte 5. Population Balance Model 6. Adjoint Solver 7. Single-Potential Battery Model 8. Dual-Potential MSMD Battery Model 2357Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the S ingle-P otential Empir ical Battery Model 9. PEM Fuel Cell Model Enter Module Number: [0] 7 Selec t the single-p otential ba ttery mo del b y en tering the mo dule numb er 7. During the loading pr ocess, a Scheme libr ary containing the gr aphic al and t ext user in terface, and a UDF libr ary containing a set of user-defined func tions (UDFs) f or the ba ttery mo dule ar e loaded in to ANSY S Fluen t.This is r eported to the c onsole .The UDF libr ary also b ecomes visible as a new en try in the UDF Libr ary M anager dialo g box.The basic setup of the ba ttery mo del is p erformed aut oma tically when the ba ttery mo dule is succ essfully loaded . 32.2.3. Getting S tarted With the S ingle-P otential E mpir ical B attery M odel The ba ttery mo del is implemen ted b y user-defined func tions (UDFs) and scheme r outines in ANSY S Fluen t. A numb er of UDFs ar e used t o solv e the ba ttery equa tions .When y ou loaded the ba ttery add- on mo dule in the pr evious st ep ( Loading the S ingle-P otential Empir ical Battery Module (p.2357 )), UDF and scheme libr aries tha t are requir ed b y the ba ttery mo del w ere aut omatic ally loaded . Before you can b egin the pr ocess of defining y our ba ttery mo del, however, you will need t o perform some addi- tional setup tasks tha t involve allo cating user-defined memor y for the UDFs and ho oking an adjust UDF t o ANSY S Fluen t. Follow the pr ocedur e below. Onc e the mo dule has b een loaded , in or der t o set ba ttery mo del par amet ers and assign pr operties t o the r elevant regions in y our ba ttery, you need t o acc ess the ba ttery gr aphic al user in terface (the Battery Model dialo g box). To enable the ba ttery mo del: In the Outline View under the Models branch, right-click Battery Model and click Edit... in the menu tha t op ens. Setup → Models → Battery M odel Edit... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2358Modeling B atteriesFigur e 32.1: The B attery M odel Option in the Outline View This op ens the Battery Mo del dialo g box. Onc e you op en the Battery M odel dialo g box, you c an selec t the Enable B attery M odel check b ox to enable the mo del so tha t you c an use it in y our simula tion. Enabling the mo del e xpands the dialo g box to reveal additional mo del options and solution c ontrols. The Model P aramet ers tab of the Battery M odel dialo g box allo ws you t o acc ess gener al mo del settings when solving a ba ttery pr oblem. Likewise , the Separ ator tab allo ws you t o set options f or the ba ttery separ ator. Finally , the Electric F ield tab allo ws you t o set par amet ers f or the elec tric field . For additional information, see the f ollowing sec tions: 32.2.3.1. Specifying S ingle-P otential Empir ical Battery Model P aramet ers 32.2.3.2. Specifying S epar ator P aramet ers 32.2.3.3. Specifying E lectric Field P aramet ers 2359Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the S ingle-P otential Empir ical Battery Model32.2.3.1. Specifying S ingle-P otential E mpiric al B attery Mo del P aramet ers The Model P aramet ers tab of the Battery M odel dialo g box allo ws you t o tur n on or off v arious options when solving a ba ttery pr oblem. Figur e 32.2: The B attery M odel D ialo g Box (M odel P aramet ers Tab) In the Model P aramet ers tab , you c an set v arious mo del options , solution c ontrols, elec trical par a- met ers, as w ell as ac tivation par amet ers. For Model Options , you c an: •Enable J oule H eat Sour ce in or der t o include the J oule H eating sour ce in the ther mal ener gy equa tion (Equa tion 24.8 ). (enabled b y default) •Enable E-C hem H eat Sour ce in or der t o include the hea t sour ce due t o elec trochemistr y in the ther mal ener gy equa tion ( Equa tion 24.9 ). (enabled b y default) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2360Modeling B atteries•Enable S epar ator S ubmo del in or der t o sp ecify y our o wn v alues f or the Separ ator Thick ness and Res- istivit y, inst ead of the Y Coefficien ts, for mo deling the separ ator. Note tha t when this option is selec ted, the inputs f or the Y Coefficien ts are gr ayed out , and the Separ ator P roperty fields ar e ac tive in the Separ ator tab . Note The separ ator submo del is pr ovided as an alt ernative metho d to calcula te the separ ator resistanc e.When the option is enabled , the separ ator resistanc e is c omput ed as R = (separ ator r esistivit y)*(separ ator thick ness) , wher e separ ator r esistivit y and separ ator thick ness are supplied b y you.When the option is disabled (the default), the separ ator resistanc e is comput ed b y For Solution C ontrols, you c an set the Current Under-Relaxa tion F actor. For Electrical P aramet ers, you c an set the Nominal C apacit y (the c apacit y of the ba ttery cell). If you selec t Fixed D oD (for st eady sta te simula tion only), then y ou c an sp ecify a Nominal D oD value (depth of dischar ge). For the Solution Options , if y ou selec t: •Specified C-R ate, you c an set a v alue f or the Dischar ge C-R ate (the hour ly rate at which a ba ttery is dischar ged). In this c ase, the t otal cur rent at the c athode tabs ar e fix ed as the pr oduc t of C-R ate and N ominal C apacit y, while the elec trical potential is anchor ed a t zero on the ano de tabs . •Specified S ystem C urrent, you c an set a v alue f or the t otal cur rent (applied t o the ano de tabs). In this c ase, the elec trical potential is set t o zero at the ano de tabs . •Specified S ystem Voltage , you c an set a v alue f or the System Voltage (applied t o the c athode tab; the ano de tab has a v oltage of 0 V). •Set in B oundar y Conditions , you c an set the UDS b oundar y conditions dir ectly, for e xample , the voltage v alue or the cur rent value (sp ecified flux), using the Boundar y Conditions task page in ANSY S Fluen t for the sp ecific fac e zone . Note When the st eady sta te solv er is used , the Fixed D oD option has t o be selec ted. Al- ternatively, the tr ansien t solv er can b e used t o analyz e variable D oD pr oblems . For Activation P aramet ers, you c an sp ecify the U C oefficien ts for Equa tion 24.3 and the Y Coefficien ts for Equa tion 24.4 (if the Enable S epar ator S ubmo del option is disabled). Note The c oefficien t values f or the Activation P aramet ers are based on ba ttery cell p olar ization test cur ves. Obtaining c oefficien t values (other than the default v alues) c an b e dep endan t on y our ba ttery configur ation and ma terial pr operties. For mor e inf ormation ab out c oeffi- cien t values , refer to the w ork performed b y Gu 193.You will lik ely need t o mak e adjust- men ts (f or e xample , if y ou ar e mo deling lithium ion ba tteries) when using y our o wn e xper- imen tal da ta. 2361Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the S ingle-P otential Empir ical Battery ModelYou c an also sp ecify the Temp erature Corrections , if needed , though the default v alues ar e suitable in most c ases .The t emp erature corrections pr ovide additional accur acy to acc oun t for lo cal temp er- ature eff ects, and c orrespond t o the t emp erature terms in Equa tion 24.6 and Equa tion 24.7 . 32.2.3.2. Specifying S epar ator P aramet ers The Separ ator tab of the Battery M odel dialo g box allo ws you t o selec t interfaces as the Anode Separ ator, the Catho de S epar ator, as w ell as the Separ ator P roperties , if appr opriate. Figur e 32.3: The B attery M odel D ialo g Box (S epar ator Tab) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2362Modeling B atteriesIn the Separ ator tab , specify the z ones f or the Anode S epar ator and the Catho de S epar ator. If the Enable S epar ator S ubmo del option is selec ted in the Model P aramet ers tab , you c an sp ecify the Separ ator P roperties such as the Separ ator Thick ness and the Separ ator Resistivit y. 32.2.3.3. Specifying Elec tric F ield P aramet ers The Electric F ield tab of the Battery M odel dialo g box allo ws you t o set the pr operties of the Con- duc tive Regions ,Contact Surfaces, and the External C onnec tors. Figur e 32.4: The B attery M odel D ialo g Box (E lectric F ield Tab) In the Electric F ield tab , specify the z ones f or the Conduc tive Regions and the Contact Surfaces (as w ell as the Contact Resistanc e) for an y selec ted c ontact sur face. In addition, you c an sp ecify the ano de and c athode tap sur faces for the Ex ternal C onnec tors of the ba ttery. 32.2.4. Solution C ontrols f or the S ingle-P otential E mpir ical B attery M odel When y ou use the B attery mo del, the elec tric potential equa tion is solv ed in addition t o other fluid dynamic equa tions , dep ending on the t ype of simula tion. The elec tric potential equa tion is list ed as one of the solv ed equa tions b y ANSY S Fluen t in the Equa tion dialo g box, wher e it c an b e enabled/dis- abled in the solution pr ocess. Solution → Controls → Equa tions ... Also, keep in mind the Advanc ed S olution C ontrols dialo g box, wher e you c an set the multigr id cycle type for the elec tric potential equa tion, if requir ed. 2363Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the S ingle-P otential Empir ical Battery ModelSetup → Controls → Advanc ed... Note When cho osing a solution metho d for y our simula tion, the L east S quar es C ell B ased gr adien t spatial discr etiza tion metho d is r ecommended b ecause of its gr eater accur acy.The G reen- Gauss C ell B ased gr adien t spa tial discr etiza tion metho d is adequa te if the mesh is e venly spac ed in the sy stem cur rent dir ection, and if ther e ar e not lar ge diff erences in the elec trical conduc tivities in the ma terials used in the simula tion. Note In tr ansien t simula tions , you should star t the c alcula tion with a smaller time st ep (1 ~ 2 seconds) initially .The time st ep c an b e incr eased t o a lar ge v alue (f or e xample , 30 sec onds), however, you will lik ely need t o sear ch f or a suitable v alue t o mak e sur e reasonable c onver- genc e is achie ved within each time st ep. 32.2.5. Postpr ocessing the S ingle-P otential E mpir ical B attery M odel You c an p erform p ost-pr ocessing using standar d ANSY S Fluen t quan tities and b y using user-defined scalars and user-defined memor y allo cations .When using the B attery mo del, the f ollowing additional variables will b e available f or p ostpr ocessing: •Under User-D efined Sc alars ... –Electric P otential –Diff C oef of E lectric P otential (the elec trical conduc tivit y of the c onduc tive field) •Under User-D efined M emor y... –Interface Current Densit y (the separ ator cur rent densit y, tha t is J (A/m2)) –X Current Densit y –Y Current Densit y –Z Current Densit y –Magnitude of C urrent Densit y –Volumetr ic O hmic S our ce (the ener gy sour ce due t o the elec tric Joule hea ting) –Electrochemistr y Sour ce –Activation O ver-P otential (the net elec trode p otential change acr oss the ano de and c athode of the system when ther e is a cur rent flo wing thr ough the sy stem, tha t is, (Volts) –Depth of D ischar ge –U Func tion Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2364Modeling B atteries–Y Func tion –Separ ator Voltage Jump (the net p otential diff erence acr oss the separ ator) –Effective Electric Resistanc e (the eff ective resistanc e of the separ ator used in the p otential field c alcu- lation) –Other By default , the ANSY S Fluen t Battery Model defines se veral user-defined sc alars and user-defined memor y allo cations , descr ibed in Table 32.1: User-D efined Sc alar A llocations (p.2365 ) and Table 32.2: User- Defined M emor y Allocations (p.2365 ). Table 32.1: User-D efined Sc alar A llocations Electric Potential ( Volts) UDS 0 Diff C oef of E lectric Potential UDS 1 Table 32.2: User-D efined M emor y Allocations Interface Current Densit y UDM 0 X Current Densit y UDM 1 Y Current Densit y UDM 2 Z Current Densit y UDM 3 Magnitude of C urrent Densit y UDM 4 Volumetr ic O hmic S ource UDM 5 Electrochemistr y Source UDM 6 Activation O ver-P otential UDM 7 Depth of D ischar ge UDM 8 U Function UDM 9 Y Function UDM 10 Separ ator Voltage J ump UDM 11 Effective Electric Resistanc e UDM 12 Other UDM 13 Note •For field v ariables tha t are stored in UDM, use the c orresponding v ariables f or p ost pr o- cessing . Post pr ocessing the UDM itself is not r ecommended . •For reviewing simula tion r esults in CFD P ost f or cases in volving UDM or UDS, export the solution da ta as CFD-P ost-c ompa tible file (.cdat ) in F luen t and then load this file in to CFD-P ost. 2365Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the S ingle-P otential Empir ical Battery Model32.2.6. User-A ccessible F unc tions You c an inc orporate your o wn f ormula tions and da ta for the pr operties of the ba ttery using the batt_user.c sour ce code file . The f ollowing listing r epresen ts a descr iption of the c ontents of the batt_user.c sour ce code file: •real CONDUCTIVITY_CELL(cell_t c, Thread *t) : Retur ns v alues f or the elec trical conduc tivit y for cells inside c onduc tive zones , overwriting the v alues set in the Electric Field tab of the Battery M odel dialo g box. •real CONTACT_RESIST_FACE(cell_t f, Thread *t) : Retur ns v alues f or the elec trical contact resistanc e, overwriting the v alues set in the Electric Field tab of the Battery M odel dialo g box. •real Compute_U (face_t f, Thread *t, real DOD, real dUdJ, real a[], real *dUdJ) : Retur ns v alues f or b oth U and the der ivative of U with r espect to J (dUdJ ). Note tha t DOD represen ts the depth of dischar ge and a[] is the set of U c oefficien ts. •real Compute_Y (face_t f, Thread *t, real DOD, real b[]) : Retur ns v alues f or Y. Note tha t DOD represen ts the depth of dischar ge and b[] is the set of Y coefficien ts. For mor e inf ormation, see the f ollowing sec tions: 32.2.6.1. Compiling the C ustomiz ed B attery Source Code 32.2.6.1. Compiling the C ustomiz ed B attery Sour ce Code This sec tion includes instr uctions on ho w to compile a cust omiz ed B attery user-defined mo dule . Note that you c an also r efer to the file INSTRUCTIONS-CLIENT tha t comes with y our distr ibution (see addons/battery ). Imp ortant It is assumed tha t you ha ve a basic familiar ity with c ompiling user-defined func tions (UDFs). For an in troduc tion on ho w to compile UDFs , refer to the Fluen t Customiza tion M anual . You will first w ant to use a lo cal copy of the battery directory in the addons directory before you recompile the B attery mo dule . 32.2.6.1.1. Compiling the C ustomiz ed S our ce Code Under Linux 1.Make a lo cal copy of the battery directory. Do not cr eate a symb olic link. Imp ortant The cust om v ersion of the libr ary must b e named acc ording t o the c onvention used by ANSY S Fluen t: for e xample ,battery . 2.Change dir ectories t o the battery/src directory. 3.Make changes t o the batt_user.c file. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2366Modeling B atteries4.Edit the makefile_slave.nt located in the src/ directory and mak e sur e tha t the FLUENT_INC variable c orrectly r efers t o the cur rent ANSY S Fluen t installa tion dir ectory. Be careful not t o lea ve an y trailing spac es when y ou mak e your changes . 5.Define the FLUENT_ADDONS environmen t variable t o correspond t o your cust omiz ed v ersion of the Battery mo dule . 6.Change dir ectories t o the battery/ directory. 7.Issue the f ollowing make command: make FLUENT_INC=[ansys_inc/v195/fluent] FLUENT_ARCH=[arch] -f Makefile-client wher e your_arch is lnx86 on LINUX, or ultra on the Sun op erating sy stem, etc. The f ollowing e xample demonstr ates the st eps r equir ed t o set up and r un a cust omiz ed v ersion of the B attery mo dule tha t is lo cated in a f older c alled home/sample : •Make a dir ectory (for e xample ,mkdir -p /home/sample ). •Copy the default addon libr ary to this lo cation. cp -RH [ansys_inc/v195/fluent]/fluent19.5.0/addons/battery /home/sample/battery •Using a t ext edit or, mak e the appr opriate changes t o the batt_user.c file lo cated in /home/sample/battery/src/batt_user.c •Edit the makefile_slave.nt located in the src/ directory and mak e sur e tha t the FLUENT_INC variable c orrectly r efers t o the cur rent ANSY S Fluen t installa tion dir ectory. Be careful not t o lea ve an y trailing spac es when y ou mak e your changes . •Build the libr ary. cd /home/sample/battery make FLUENT_INC=[ansys_inc/v195/fluent] FLUENT_ARCH=[arch] -f Makefile-client •Set the FLUENT_ADDONS environmen t variable (using CSH, other shells will diff er). setenv FLUENT_ADDONS /home/sample •Start ANSY S Fluen t and load the cust omiz ed mo dule using the t ext interface command . 32.2.6.1.2. Compiling the C ustomiz ed S our ce Code Under Windo ws 1.Open Visual S tudio .NET at the DOS pr ompt. 2.Make sur e tha t the FLUENT_INC environmen t variable is c orrectly set t o the cur rent ANSY S Fluen t in- stalla tion dir ectory (for e xample ,ANSYS Inc\v195\fluent ). 3.Make a lo cal copy of the battery folder . Do not cr eate a shor tcut. 4.Enter the battery\src folder . 2367Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the S ingle-P otential Empir ical Battery Model5.Make changes t o the batt_user.c file. 6.Define the FLUENT_ADDONS environmen t variable t o correspond t o your cust omiz ed v ersion of the Battery mo dule . 7.Retur n to the battery folder . 8.Issue the f ollowing c ommand in the c ommand windo w: nmake /f makefile_master-client.nt 32.3. Using the D ual-P otential MSMD and C ell N etwork Battery M odels This sec tion descr ibes ho w to use the MSMD and C ell N etwork mo deling c apabilit y in ANSY S Fluen t. Only the pr ocedur al st eps r elated t o ba ttery mo deling ar e sho wn her e. For inf ormation ab out inputs related t o other mo dels used in c onjunc tion with the ba ttery mo del, see the appr opriate sec tions f or those mo dels in the ANSY S Fluen t Fluen t User's G uide (p.1). For mor e details on the mo deling appr oach, refer to Dual-P otential MSMD and C ircuit N etwork Battery Models . Information ab out using the mo del is pr esen ted in the f ollowing sec tions: 32.3.1. Limita tions 32.3.2. Geometr y Definition 32.3.3. Loading the D ual-P otential MSMD B attery Module 32.3.4. Setting up the D ual-P otential MSMD B attery Model 32.3.5. Using P aramet er Estima tion Tools 32.3.6. Initializing the B attery Model 32.3.7. Modifying M aterial P roperties 32.3.8. Solution C ontrols f or the D ual-P otential MSMD B attery Model 32.3.9. Postpr ocessing the D ual-P otential MSMD B attery Model 32.3.10. User-A ccessible F unctions 32.3.1. Limita tions Note the f ollowing limita tions when using the D ual-P otential MSMD B attery mo del: •For ba ttery pack simula tions , all ba tteries in the pack must b e iden tical initially , having the same ba ttery type with the same initial c onditions . •For ba ttery pack simula tions , all ba tteries in the pack must ha ve the nPmS c onnec tion pa ttern; tha t is, n batteries c onnec ted in par allel, and then m such units c onnec ted in ser ies. •A conduc tive zone must b e continuous . Disconnec ted z ones c annot b e gr oup ed as one en tity. •System p ositiv e and nega tive tabs must b e continuous sur faces. Disconnec ted fac es c annot b e gr oup ed together as one en tity. •The p ositiv e and nega tive tabs must b e connec ted b y either the r eal tab/busbar c onduc tive volumes or the vir tual c onnec tions defined thr ough a file . •A ba ttery tab c annot b e dir ectly c ontact another ba ttery tab .They must b e connec ted b y busbars . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2368Modeling B atteries32.3.2. Geometr y Definition In the MSMD and C ell N etwork framew orks, the nega tive and p ositiv e cur rent collec tors, ano de, and cathode ar e not r esolv ed, and the ba ttery is r egar ded as a homo geneous b ody.The c omputa tional mesh do es not ha ve to be adjust ed t o all la yers pr esen t in the ba ttery domain. The f ollowing z ones have to be iden tified when cr eating the ba ttery mesh: •Cell •Tab •Busbar (f or ba ttery pack c ases with r eal ba ttery connec tions) When using the r eal ba ttery connec tions y ou need t o cr eate busbar z ones and sp ecify them under Basbar C omp onen ts (see Specifying C onduc tive Zones (p.2388 ) for details). Since both tab z ones and busbar z ones ar e passiv e zones , you c an gr oup them all under busbar f or simplicit y. However, busbars sometimes ma y not b e assigned t o the tab z one c ategor y because a ba ttery tab z one c annot dir ectly connec t to another ba ttery tab z one . When using the vir tual ba ttery connec tions y ou do not need t o cr eate busbar z ones .You only need to cr eate tab z ones (if y ou ha ve tab v olumes) and sp ecify them under Tab C omp onen ts (see Specifying Conduc tive Zones (p.2388 ) for details). 32.3.3. Loading the D ual-P otential MSMD B attery M odule The ba ttery mo dule is loaded in to ANSY S Fluen t thr ough the t ext user in terface (TUI). The mo dule c an be loaded only when a v alid ANSY S Fluen t case file has b een set or r ead.The t ext command t o load the mo dule is define → models → addon-module A list of ANSY S Fluen t add-on mo dules is displa yed: Fluent Addon Modules: 0. none 1. MHD Model 2. Fiber Model 3. Fuel Cell and Electrolysis Model 4. SOFC Model with Unresolved Electrolyte 5. Population Balance Model 6. Adjoint Solver 7. Single-Potential Battery Model 8. Dual-Potential MSMD Battery Model 9. PEM Fuel Cell Model Enter Module Number: [0] 8 Selec t the dual-p otential MSMD ba ttery mo del b y en tering the mo dule numb er 8. During the loading process, a Scheme libr ary containing the gr aphic al and t ext user in terface, and a UDF libr ary containing a set of user-defined func tions (UDFs) f or the ba ttery mo dule ar e loaded in to ANSY S Fluen t.This is reported t o the c onsole .The UDF libr ary also b ecomes visible as a new en try in the UDF Libr ary Manager dialo g box.The basic setup of the ba ttery mo del is p erformed aut oma tically when the ba ttery module is succ essfully loaded . 2369Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the D ual-P otential MSMD and C ell N etwork Battery Models32.3.4. Setting up the D ual-P otential MSMD B attery M odel Onc e the mo dule has b een loaded , you c an enable the D ual-P otential MSMD B attery Model, set ba ttery model par amet ers and assign pr operties t o the r elevant regions in y our ba ttery. To enable the MSMD ba ttery mo del: In the Outline View under the Models branch, right-click MSMD Battery M odel and click Edit... in the menu tha t op ens. Setup → Models → MSMD B attery M odel Edit... Figur e 32.5: The MSMD B attery M odel Option in the Outline View In the MSMD B attery M odel dialo g box tha t op ens, selec t the Enable B attery M odel check b ox to activate the mo del. The MSMD B attery M odel dialo g box expands t o reveal additional mo del options and solution c ontrols. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2370Modeling B atteriesThe inputs f or the ba ttery mo del ar e en tered using the f ollowing tabs: Model Options contains the gener al mo del settings t o define pr oblems using the ba ttery mo del. Model P aramet ers is wher e you sp ecify the par amet ers t o be used f or solving the mo del equa tions . Conduc tive Zones allows you t o selec t zones f or the ac tive, tab and busbar c omp onen ts. Electric C ontacts allows you t o define the c ontact sur face and e xternal c onnec tors. Advanc ed Option allows you t o qukck ly check the selec ted elec trochemic al submo del b ehavior using the E chem mo del in a standalone mo de, and also enable a ther mal abuse mo del and sp ecify its par amet ers. Note When setting up the mo del, you c an click the Apply butt on t o sa ve your input v alues and your choic es for y our mo del. To restore the last sa ved settings f or all tabs , click the Reset butt on. For additional inf ormation, see the f ollowing sec tions: 32.3.4.1. Specifying B attery Model Options 32.3.4.2. Specifying B attery Model P aramet ers 32.3.4.3. Specifying C onduc tive Zones 32.3.4.4. Specifying E lectric Contacts 32.3.4.5. Specifying A dvanced Option 32.3.4.6. Specifying Ex ternal and In ternal S hort-Circuit R esistanc es 32.3.4.1. Specifying B attery Mo del O ptions In the Model Options tab , you c an selec t the elec trochemic al ba ttery submo del and set v arious model options , solution c ontrols, and elec trical par amet ers. 2371Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the D ual-P otential MSMD and C ell N etwork Battery ModelsFigur e 32.6: The MSMD B attery M odel D ialo g Box (M odel Options Tab) The f ollowing submo dels ar e available in ANSY S Fluen t under the E-Chemistr y M odels group b ox: NTGK E mpir ical M odel is an empir ical mo del. This is the simplest and the least e xpensiv e mo del. It also r equir es the f ewest model inputs .The mo del uses the same NT GK metho d as tha t used b y the S ingle-P otential Empir ical model. However, in this c ase, it solv es two potential equa tions c ontinuously inst ead of one p otential equa tion with a jump c ondition a t the separ ator o ver all c onduc tive zones .The mo del c annot accur ately captur e the ba ttery's d ynamic (iner tial) r esponse . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2372Modeling B atteriesEquiv alen t Circuit M odel is a semi-empir ical mo del. It has limit ed c apabilit y for pr edic ting the ba ttery dynamic b ehavior. Newman P2D M odel is the most c ompr ehensiv e ph ysics-based ba ttery mo del. It is c omputa tionally e xpensiv e, and it r equir es extensiv e user input of ba ttery-related fundamen tal inf ormation. User-defined E-M odel is the user-sp ecified elec trochemic al submo del. To be able t o use this option in the F luen t MSMD metho d framew ork, you must pr ovide the void user_defined_echem_model() func tion in the cust omizable cae_user.c sour ce code file . For Solution M etho d for E-F ield , if y ou selec t: •Circuit N etwork M etho d, none or one p otential equa tion will b e solv ed, dep ending on whether J oule heating in passiv e zones is included or not. See Circuit N etwork Solution M etho d in the Fluent Theor y Guide for mor e inf ormation ab out this metho d. •Solving Transp ort Equa tion , two potential equa tions will b e solv ed dur ing each it eration in the simula tion. •Reduc ed Or der M etho d, the solution will b e obtained (fast er) using the r educ ed or der metho d (R OM). You c an use this option if the t wo conditions list ed in Reduc ed Or der S olution M etho d (R OM) are met. Note tha t, prior t o using the R OM, you must first r un a simula tion with the Solving Transp ort Equa tion option f or a t least thr ee time st eps. ANSY S Fluen t will use these r esults as r eference po- tential fields f or the R OM metho d. Onc e you ha ve selec ted Reduc ed Or der M etho d, you c an set Numb er of S ub-S teps/T ime S tep. Using this v alue , you c an sp ecify the r atio of the time st eps f or ther mal and elec tro-chemistr y cal- cula tions . For e xample , if the Numb er of S ub-S tepes/T ime S tep is set t o 10, the solv er will use one t enth of the CFD time st ep f or the elec tro-chemistr y calcula tion. Imp ortant If internal shor t cir cuit o ccurs in a ba ttery, the Reduc ed Or der M etho d cannot b e used . For Energy Sour ce Options , you c an: •Enable J oule H eat in Tab/Busbar Z ones (default) in or der t o include the J oule hea ting sour ce in the ther mal ener gy Equa tion 24.10 in the ba ttery passiv e conduc ting z ones , including tabs and busbars , •Enable J oule H eat in A ctive Zones (default) in or der t o include the J oule H eating sour ce in the ther mal ener gy equa tion Equa tion 24.10 . •Enable E-C hem H eat Sour ce (default) in or der t o include the hea t sour ce due t o elec trochemistr y in the ther mal ener gy equa tion Equa tion 24.10 . For Solution C ontrols, you c an: •Set Current Under-Relaxa tion F actor.The v olumetr ic cur rent densit y used in the t wo potential equa tions are under-r elax ed acc ording t o this fac tor.The default v alue of 0.8 may be sufficien t for most c ases .The values in the r ange of 0.8–1.0 ar e recommended . 2373Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the D ual-P otential MSMD and C ell N etwork Battery Models•Set Voltage C orrection U nder-Relaxa tion F actor.The default v alue of 1.0 is acc eptable f or most c ases . You should r educ e this v alue only if the c onvergenc e difficult y occurs dur ing the solution of the p otential equa tions . •(Equiv alen t Circuit M odel and N ewman P2D M odel) S elec t the Clust er C ells check b ox to enable c ell clust ering and sp ecify the numb er of clust ers Nx,Ny, and Nz in X, Y, and Z dir ections r espectively.The solv er will divide the ba ttery domain in to Nx x Ny x Nz clust ers and solv e submo del equa tions f or each clust er using clust er-a verage inf ormation. The default v alues f or Nx,Ny, and Nz are 1, 1, and 1, respectively. For the initial r un, the default settings ar e recommended .This option is a vailable only f or the Solving Transp ort Equa tion and Reduc ed Or der M etho d solution metho ds. For Electrical P aramet ers, you c an sp ecify the f ollowing op eration c onditions: •Set the Nominal C ell C apacit y (the c apacit y of the ba ttery cell). •For the Solution Options , if you selec t: –Specified C-R ate, you c an set a v alue f or the f ollowing: →Dischar ge C-R ate (the hour ly rate at which a ba ttery is dischar ged; a positiv e value means dis- char ging C-r ate and a nega tive value means char ging C-r ate). In this c ase, the t otal cur rent at the c athode tabs is fix ed as the pr oduc t of C-R ate and N ominal C apacit y, while the elec trical potential is anchor ed a t zero on the ano de tabs . →Min. Stop Voltage and Max. Stop Voltage .The simula tion will aut oma tically st op onc e the battery cell v oltage r eaches the minimum or maximum v alue . For a ba ttery pack, the ba ttery- average c ell v oltage is used . –Specified S ystem C urrent, you c an set the f ollowing: →System C urrent (applied a t the c athode tabs). A p ositiv e value means dischar ging cur rent and a nega tive value means char ging cur rent. →Min. Stop Voltage and Max. Stop Voltage . (Same as f or Specified C-r ate.) –Specified S ystem Voltage , you c an set a v alue f or the System Voltage (applied t o the c athode tab; the ano de tab has a v oltage of 0 V). –Specified S ystem P ower, you c an sp ecify the f ollowing: →System P ower. If you sp ecify the t otal p ower output fr om y our ba ttery, Fluen t solv er will ensur e that the pr oduc t of the sy stem cur rent and v oltage equals the sy stem p ower. A p ositiv e value means dischar ging p ower output and a nega tive value means char ging p ower input. →Min. Stop Voltage and Max. Stop Voltage . (Same as f or Specified C-r ate.) –Specified Resistanc e, you c an sp ecify the e xternal elec tric resistanc e in an e xternal shor t-cir cuit simula tion. →External Resistanc e. If you sp ecify the e xternal elec tric resistanc e in O hm, the F luen t solv er will ensur e tha t the r atio of the sy stem v oltage t o the sy stem cur rent equals the sp ecified e xternal resistanc e. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2374Modeling B atteries–Set in B oundar y Conditions , you c an set the UDS b oundar y conditions dir ectly, for e xample , the voltage v alue or the cur rent value (sp ecified flux), using the Boundar y Conditions task page in ANSY S Fluen t for the sp ecific fac e zone . –Using P rofile , you c an selec t Time-Scheduled or Event-Scheduled under Profile Type and provide time-dep enden t or e vent-dep enden t input (r espectively) f or the C-r ate, current, voltage , or p ower.The time-scheduled and e vent-scheduled pr ofiles enable y ou t o change the elec tric load type and elec tric value in the simula tion on the fly . Onc e the pr ofile t ype is selec ted, you c an br owse to the ASCII t ext file with either the .dat or .txt file e xtension tha t you gener ated b eforehand . The inputs f or the Time-Scheduled and Event-Scheduled profiles ar e descr ibed b elow. →The Time-Scheduled profile file must b e or ganiz ed in thr ee c olumns: 1.Time 2.Electric load v alue 3.Electric load t ype The elec tric load t ype is defined b y an in teger numb er: 0: C-rate 1: Current 2:Voltage 3: Power 4: External elec tric resistanc e For e xample , the b elow time-scheduled pr ofile: 0 15 1 500 15 1 500.1 60 3 1000 60 3 1000.1 -1 0 1500 -1 0 specifies the f ollowing ba ttery char ging sc enar io: 1.The ba ttery is dischar ged a t 15 A f or the first 500 sec onds . 2.The ba ttery dischar ge c ontinues a t 60 W for the ne xt 500 sec onds . 3.The ba ttery is char ged a t a c onstan t 1 C-r ate for the last 500 sec onds . Note •For cur rent, power, or C-r ate, a positiv e value means dischar ging and a nega tive value means char ging . 2375Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the D ual-P otential MSMD and C ell N etwork Battery Models•The unit of the v ariables in the input file is alw ays SI. ANSY S Fluen t solv er uses linear in terpolation of y our time-scheduled pr ofile da ta in the problem simula tion. If you w ant to captur e a sudden change in the pr ofile accur ately, use smaller time gaps t o descr ibe the pr ofile . →The Event-Scheduled profile file must b e or ganiz ed in the f ollowing fiv e columns: 1.Electric load t ype Just as in the time-scheduled pr ofile , the elec tric load t ype is defined b y an in teger numb er: 0: C-rate 1: Current 2:Voltage 3: Power 4: External elec tric resistanc e 2.Electric load v alue 3.Forwarding c ondition The f orwarding c ondition (FC) is defined b y an in teger numb er: 1:Time > FC_V alue 2: I < FC_V alue (dischar ging cur rent minimum) 3: I > FC_V alue (char ging cur rent maximum) 4:V < FC_V alue (sy stem v oltage minimum) 5:V > FC_V alue (sy stem v oltage maximum) 6: P < FC_V alue (dischar ging p ower minimum) 7: P > FC_V alue (char ging p ower maximum) 4.Forwarding c ondition v alue 5.Stop flag The st op flag is an in teger v alue of 0 or 1, wher e 0 sp ecifies tha t the r un should c on- tinue t o the ne xt event en try line , and 1 sp ecifies tha t the r un should end . For e xample , the b elow event-scheduled pr ofile: 0 1 4 3.5 0 1 -15 5 4.1 0 2 4.1 3 -1 1 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2376Modeling B atteriesspecifies the f ollowing sc enar io: 1.The ba ttery is dischar ged a t 1 C r ate un til the v oltage r eaches 3.5 V. 2.The ba ttery is char ged a t constan t cur rent 15 A un til the v oltage r eaches 4.1 V. 3.The ba ttery keeps char ging a t 4.1 V un til the cur rent is gr eater -1 A. The simula tion st ops after reaching this p oint. Note •For cur rent, power, or C-r ate, a positiv e value means dischar ging and a nega tive value means char ging . •The unit of the v ariables in the input file is alw ays SI. Any time-scheduled pr ofile c an b e rewritten in an e vent-scheduled pr ofile f ormat, but not vic e-versa. The e xample sho wn in the time-scheduled pr ofile c an b e redefined in an event-scheduled pr ofile f ormat as f ollows. 1 15 1 500 0 3 60 1 1000 0 0 -1 1 1500 1 Both pr ofile t ypes c an b e read in to ANSY S Fluen t.You c an cho ose the most c onvenien t one t o use in y our sp ecific applic ation. 32.3.4.2. Specifying B attery Mo del P aramet ers The Model P aramet ers tab of the MSMD B attery M odel dialo g box allo ws you t o sp ecify the sub- model-sp ecific par amet ers t o be used f or solving the submo del equa tions .The Model P aramet ers tab c ontains only the en try fields f or par amet ers r elated t o the elec trochemic al submo del y ou ha ve chosen in the Model Option tab . A detailed descr iption of inputs f or each submo del is giv en in the sections tha t follow. 32.3.4.2.1. Inputs f or the NT GK Empir ical M odel 32.3.4.2.2. Inputs f or the E quiv alen t Circuit M odel 32.3.4.2.3. Inputs f or the N ewman ’s P2D M odel 32.3.4.2.4. Input f or the U ser-D efined E-M odel 2377Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the D ual-P otential MSMD and C ell N etwork Battery Models32.3.4.2.1. Inputs for the NT GK E mpiric al Mo del Figur e 32.7: Model P aramet ers Tab—NT GK M odel For the NTGK E mpir ical M odel, you c an define the mo del par amet ers used in Equa tion 24.14 using the f ollowing Data Types: •Polynomial When using the Polynomial data type, you c an dir ectly sp ecify p olynomial c oefficien ts for , , and t emp erature correction in Equa tion 24.14 . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2378Modeling B atteries•Table When using the Table data type, you c an define a 2D lo okup table f or each NT GK mo del par amet er. Tabular da ta ar e en tered in the c orresponding par amet er da ta table dialo g box tha t op ens b y click ing the r elevant butt on in the NT GK par amet er da ta table gr oup b ox (see Figur e 32.8: NTGK U-par amet er D ata Table D ialog Box (p.2380 )). 2379Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the D ual-P otential MSMD and C ell N etwork Battery ModelsFigur e 32.8: NTGK U-par amet er D ata Table D ialo g Box For each NT GK mo del par amet er, you c an sp ecify up t o 20 DOD le vels and t emp erature levels. For each DOD-t emp erature pair , you must en ter the c orresponding mo del par amet er v alue . Each Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2380Modeling B atteriestable c an b e exported t o or imp orted fr om a file b y click ing Write or Read , respectively, in the paramet er da ta table dialo g box. Note •The mo del par amet ers f or the NTGK M odel P olar ization P aramet ers are based on ba ttery cell p olar ization t est cur ves. Obtaining mo del par amet ers (other than the default v alues) c an be dep endan t on y our ba ttery configur ation and ma terial pr operties.The default v alues ar e taken fr om K im’s pap er 273. If you mo del a ba ttery ha ving a diff erent design, you must pr ovide a diff erent set of ba ttery par amet ers. •ANSY S Fluen t provides the par amet er estima tion t ool for computing and func tions fr om the ba ttery's t esting da ta—c onstan t dischar ging cur ves.The t ool is a vailable via the t ext-user- interface (TUI). For details , see Using P aramet er Estima tion Tools (p.2396 ). You c an also set v alues f or Initial D oD and Referenc e Capacit y ( in Equa tion 24.12 ).The default value of 0 for Initial D oD indic ates the fully-char ged sta te of the ba ttery cell.Referenc e Capacit y is the c apacit y of the ba ttery tha t is used in e xperimen ts to obtain the and mo del par amet ers. Nominal and r eference capacities ma y ha ve diff erent values . 2381Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the D ual-P otential MSMD and C ell N etwork Battery Models32.3.4.2.2. Inputs for the E quiv alent C ircuit Mo del Figur e 32.9: Model P aramet ers Tab—E quiv alen t Circuit M odel For the Equiv alen t Circuit M odel, you c an define r esist ors' r esistanc es (Rs, R1, and R2), capacit ors' capacitanc es (C1 and C2), and the op en cir cuit v oltage ( Voc) using the f ollowing Data Types: •Chen's or iginal Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2382Modeling B atteriesFor the Chen's or iginal data type, you need t o sp ecify all c oefficien ts in Equa tion 24.18 . •Polynomial For the Polynomial data type, you c an dir ectly sp ecify p olynomial c oefficien ts in Equa tion 24.17 . •Table For the Table data type, you c an define a 2D lo okup table f or each ECM par amet er. See Inputs for the NT GK Empir ical M odel (p.2378 ) for mor e inf ormation on ho w to define mo del par amet ers in a table da ta type. In addition, you c an tur n on the Using diff erent coefficien t for char ging and dischar ging option and sp ecify the c oefficien ts for Charging par amet ers. You c an also set v alues f or Initial S tate of C harge and Referenc e Capacit y ( in Equa tion 24.16 ). The default v alue of 1 for Initial S tate of C harge indic ates the fully-char ged sta te of the ba ttery cell.Referenc e Capacit y is the c apacit y of the ba ttery tha t is used in e xperimen ts to obtain the model par amet ers. Note tha t nominal and r eference capacities ma y ha ve diff erent values . Note •The v alues of mo del par amet ers f or the Equiv alen t Circuit M odel are ba ttery sp ecific and need t o be sp ecified b efore conduc ting a simula tion. The default v alues ar e tak en fr om C hen 90. If you mo del a ba ttery of diff erent design, you should sp ecify a diff erent set of ba ttery paramet ers. •ANSY S Fluen t provides the par amet er estima tion t ool for computing the ECM par amet ers from the ba ttery's t esting da ta—t ypic ally, the HPPC da ta.The t ool is a vailable via the t ext- user-in terface (TUI). For details , see Using P aramet er Estima tion Tools (p.2396 ). 2383Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the D ual-P otential MSMD and C ell N etwork Battery Models32.3.4.2.3. Inputs for the N ewman ’s P2D Mo del Figur e 32.10: Model P aramet ers Tab—N ewman ’s P2D M odel The f ollowing par amet ers ar e available under Model P aramet ers for the N ewman ’s P2D mo del: Thick ness are , , and in Equa tion 24.31 . Numb er of G rids is a numb er of gr id p oints used t o discr etize the p ositiv e elec trode, nega tive elec trode, and separ ator zones . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2384Modeling B atteriesGrid S ize Ratio is used t o create a biased mesh. The default v alue of 1 c orresponds t o a unif orm mesh. Particle D iamet er is the par ticle diamet er of the ac tive ma terial. Numb er of G rids in S olid is the numb er of gr id p oints used t o discr etize the spher e of par ticles . Grid S ize Ratio in S olid is used t o create a biased mesh f or the solid phase .The default v alue of 1 c orresponds t o a unif orm mesh. Max. Solid Li+ C onc is the maximum c oncentration of Lithium in the solid phase (used in Equa tion 24.27 ). Stoi. at 0% SOC is the st oichiometr y at 0% SOC tha t is used t o comput e theor etical capacit y and initial lithium c oncen- tration in the elec trode. Stoi. at 100% SOC is the st oichiometr y at 100% SOC tha t is used t o comput e theor etical capacit y and initial lithium c on- centration in the elec trode. Init . Solid Li+C onc . is the initial lithium c oncentration in the elec trode. Init . Electrolyt e Li+C onc . is the initial lithium c oncentration in the elec trolyt e phase . Volume F raction of E lectrolyt e is the v olume fr action of the elec trolyt e ma terial in the elec trode, in Equa tion 24.28 . Filler F raction is the v olume fr action of the filler ma terial in the elec trode, in Equa tion 24.28 . Ref. Diffusivit y is the diffusion c oefficien t of lithium ion in the elec trode a t reference temp erature =25°C, in Equa tion 24.28 . Activation E nergy E_d is in Equa tion 24.28 . Bruggeman Tortuosit y exponen t is the B ruggeman t ortuosit y exponen t, in Equa tion 24.28 . Conduc tivit y is the elec tric conduc tivit y, in Equa tion 24.28 . Ref. Rate Constan t is the r ate constan t at reference temp erature =25°C, in Equa tion 24.28 . Activation E nergy E_r is in Equa tion 24.28 . 2385Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the D ual-P otential MSMD and C ell N etwork Battery ModelsTrans . Coef. a is the char ge tr ansf er coefficien t at ano de, in Equa tion 24.27 . Trans C oef. c is the char ge tr ansf er coefficien t at cathode, in Equa tion 24.27 . Electrolyt e Diffusivit y is the diffusion c oefficien t of Li+ in the elec trolyt e phase , in Equa tion 24.27 . t+ F actor is the tr ansf erence numb er of lithium ion, in Equa tion 24.28 . You c an also set v alues f or Initial S tate of C harge.The default v alue of 1 for Initial S tate of C harge indic ates the fully-char ged sta te of the ba ttery cell. Theor etic al C apacit y is c omput ed fr om the N ewman input par amet ers aut oma tically and r eported in the MSMD B attery M odel dialo g box. By default , ANSY S Fluen t discr etizes the lithium c onser vation equa tion and solv es it numer ically. ANSY S Fluen t also off ers an option t o use the r educ ed or der metho d to solv e the lithium diffusion equa tion in solid 77.To use this metho d, selec t the Use A nalytic al Cs check b ox and en ter the v alue for the Cs F unc tion Or der. Note Model par amet ers ar e ba ttery sp ecific .The default v alues ar e tak en fr om C ai & White 77. To simula te a ba ttery of diff erent design, you should pr ovide a user-sp ecified set of ba ttery paramet ers. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2386Modeling B atteries32.3.4.2.4. Input for the User -Defined E-Mo del Figur e 32.11: Model P aramet ers Tab—U ser-D efined E-M odel The f ollowing par amet ers ar e available under User-D efined E-C hem M odel P aramet ers: Numb er of memor ies p er c ell is the numb er of submo del par amet ers tha t need t o be sa ved p er computa tional c ell dur ing a simula tion. Initial SOC is the v alue of the ba ttery initial sta te of char ge. Referenc e Capacit y is the ba ttery capacit y (A h). 2387Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the D ual-P otential MSMD and C ell N etwork Battery Models32.3.4.3. Specifying C onduc tive Zones The Conduc tive Zones tab of the MSMD B attery M odel dialo g box allo ws you t o sp ecify the ac tive, tab, and busbar z ones . Figur e 32.12: The MSMD B attery M odel D ialo g Box (C onduc tive Zones Tab) In the Conduc tive Zones tab , selec t the appr opriate zones f or the Active Comp onen ts,Tab C om- ponen ts, and , if y ou simula te the ba ttery pack with the r eal ba ttery connec tions , the Basbar C om- ponen ts. If you simula te the ba ttery pack with the vir tual ba ttery connec tions , do not selec t an y zones under Basbar C omp onen ts. Battery cells ar e mo deled as ac tive zones; and ba ttery tabs and busbars ar e mo deled as passiv e zones . Electrochemic al reactions o ccur only in the ac tive zones .The p otential field is solv ed in b oth ac tive and passiv e zones . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2388Modeling B atteries32.3.4.4. Specifying Elec tric C ontac ts The Electric C ontacts tab of the MSMD B attery M odel dialo g box allo ws you t o set the pr operties of the Contact Surfaces and the External C onnec tors. Figur e 32.13: The MSMD B attery M odel D ialo g Box (E lectric C ontacts Tab) If you w ant to consider c ontact resistanc e, selec t zones f or the Contact Surfaces and set the Contact Resistanc e for an y selec ted c ontact sur face. When using r eal c onnec tions , define the sy stem nega tive and p ositiv e tabs under External C onnec tors. When using the vir tual c onnec tion option in a ba ttery pack simula tion, selec t the Use vir tual ba ttery connec tion check b ox and in the Specify c onnec tion file text-en try box tha t app ears , enter the file- name c ontaining the vir tual c onnec tion definition. The f ormat for the c onnec tion definition file is as f ollows: 2389Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the D ual-P otential MSMD and C ell N etwork Battery ModelsmP 1 nS 4 tab_N_1 tab_P_1 tab_N_2 tab_P_2 tab_N_3 tab_P_3 tab_N_4 tab_P_4 wher e: •The first line sp ecifies the numb er of par allel ba tteries in a stage (mP). •The sec ond line sp ecifies the numb er of stages in ser ies in a pack (nS). •The r emaining lines c ontain pairs of the fac e names of the nega tive and p ositiv e tabs f or each ba ttery. The ba ttery da ta ar e list ed in the f ollowing or der: 1P1S ... 1PnS t o mP1S ... mP nS. For the ab ove ba ttery connec tion file e xample , the ba ttery solv er establishes the 1P4S c onnec tion pattern. The f ollowing figur e sho ws the diff erent resulting c onnec tion pa tterns for the diff erent connec tion data. Onc e all c onduc tive zones and the p ositiv e and nega tive tabs ha ve been defined , ANSY S Fluen t automa tically det ects the ba ttery net work connec tion. After y ou ha ve defined all the c onduc tive zones or mo dified z one r elated da ta, click Print Battery System C onnec tion Inf ormation , and r eview the ba ttery connec tion inf ormation pr inted in the ANSY S Fluen t console windo w for an y er rors. If nec essar y, re-define the c onnec tions in the Conduc tive Zones and Electric C ontacts tabs . Note In the default ba ttery solv er configur ation, the lar gest ba ttery pack the solv er can simula te is 10P50S (50 ser ies stages with 10 par allel c onnec ted ba tteries p er stage). However, you can incr ease this limit t o simula te lar ger ba ttery packs using the f ollowing Scheme c om- mands: (rpsetvar 'battery/max-n-parallel-per-stage m) (rpsetvar 'battery/max-n-series n) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2390Modeling B atterieswher e m and n are the numb ers of maximum par allel and ser ies c onnec tions in the ba ttery pack, respectively. 32.3.4.5. Specifying A dvanc ed O ption Using the Advanc ed Option tab of the MSMD B attery M odel dialo g box, you c an: •Check the selec ted elec trochemic al mo del b ehavior b efore running the CFD c ase b y performing a quick simula tion of the elec trochemic al mo del in a standalone mo de •Enable the Thermal A buse M odel, selec t the ther mal abuse k inetics mo del, and define the c orresponding model par amet ers Figur e 32.14: The MSMD B attery M odel D ialo g Box (A dvanc ed Option Tab) 2391Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the D ual-P otential MSMD and C ell N etwork Battery ModelsRunning the Standalone E chem Mo del Prior t o running a c oupled elec trochemic al-ther mal simula tion, you should p erform a quick analy sis of y our elec trochemic al mo del b y simula ting it in a standalone mo de.The standalone mo del c alcula tion uses the op erating c onditions tha t you ha ve sp ecified in the Model Option tab (such as elec tric load type and v alue) and the echem mo del par amet ers tha t you ha ve defined in the Model P aramet ers tab.This pr eliminar y analy sis will allo w you t o confir m the elec trochemic al b ehavior of the selec ted submo del and , if nec essar y, adjust the mo del settings . To run the echem mo del in a standalone mo de: 1.Click Run E chem M odel S tandalone . 2.In the Standalone E chem M odel dialo g box tha t op ens, specify the f ollowing par amet ers: •Rep ort Time S tep:The time in terval at which the r esults will b e sa ved and r eported •Total R un Time :The t otal time f or running the stand-alone mo del simula tion •Referenc e Temp erature:The t emp erature level at which y ou w ant to simula te your elec trochemic al model 3.Initia te the elec trochemic al mo del simula tion b y click ing Draw P rofile . Onc e the c alcula tion is c omplet e, the Plot P rofile D ata dialo g box op ens. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2392Modeling B atteries4.Using the Plot P rofile D ata dialo g box, visualiz e and analyz e the r esults of the standalone echem mo del simula tion. Different profiles ar e available f or diff erent elec trochemic al mo dels . •For the NT GK mo del, a time hist ory pr ofile , called ntgk-time-hist ory-pr ofile , is gener ated af ter the calcula tion is c omplet e.You c an dr aw the X-Y plots of the f ollowing v ariables as a func tion of time: –soc: the ba ttery sta te of char ge (SOC) –voltage : the ba ttery voltage –current: the ba ttery elec tric cur rent –power: the ba ttery power output •For the ECM mo del, a time hist ory pr ofile , called ecm-time-hist ory-pr ofile , will b e gener ated. In addition to the v ariables a vailable f or the NT GK mo del, you c an also dr aw the X-Y plots of the f ollowing v ariables as a func tion of time: –v1: in Equa tion 24.16 –v2: in Equa tion 24.16 •For the N ewman P2D mo del, the f ollowing t wo pr ofiles will b e gener ated: –Time hist ory pr ofile p2d-time-hist ory-pr ofile –Spatial field pr ofile c alled p2d-field-pr ofile For the p2d-time-hist ory-pr ofile profile , you c an plot the time hist ory pr ofile f or the f ollowing variables: –current (see ab ove) –voltage (see ab ove) 2393Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the D ual-P otential MSMD and C ell N etwork Battery Models–power (see ab ove) –ce_x=0 –ce_x=lp –ce_x=lps –ce_x=lpsn –cs_x=0 –cs_x=lp –cs_x=lps –cs_x=lpsn –phis_x=0 –phis_x=lp –phis_x=lps –phis_x=lpsn –phie_x=0 –phie_x=lp –phie_x=lps –phie_x=lpsn wher e ce is the lithium-ion c oncentration in elec trolyt e phase a t diff erent locations x=0 denot es the lo cation of the outside fac e of the p ositiv e elec trode x=lp denot es the in terface of the p ositiv e elec trode and separ ator x=lps denot es the in terface between the separ ator and nega tive-elec trode x=lpsn denot es the outside fac e of the nega tive elec trode cs is the lithium c oncentration a t the sur face of the ac tive ma terial in elec trode a t different locations phis is the elec tric potential in the elec trode solid phase a t diff erent locations phie is the elec tric potential in the elec trolyt e liquid phase a t diff erent locations For the p2d-time-hist ory-pr ofile profile , you c an plot the spa tial pr ofiles of the f ollowing variables a t the end of the simula tion: –phi_e : the elec tric potential in elec trolyt e phase –phi_s : the elec tric potential in elec trode phase –ce: the lithium-ion c oncentration in elec trolyt e phase Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2394Modeling B atteries–cs_c enter: the lithium c oncentration in the c enter of the ac tive elec trode par ticles –cs_a verage : the a verage lithium c oncentration in the ac tive elec trode par ticles –cs_sur f: the lithium c oncentration a t the sur face of the ac tive elec trode par ticles Note SI units ar e alw ays used f or all the v ariables in the X-Y plot. Using the Thermal A buse mo del When y ou selec t One-equa tion k inetics mo del, you c an sp ecify the ba ttery constan ts , , , , and used in Equa tion 24.34 through Equa tion 24.35 , as w ell as the initial v alue f or . When y ou selec t Four-equa tion k inetics mo del, you c an sp ecify the ba ttery constan ts , , , , and used in Equa tion 24.36 ) thr ough Equa tion 24.40 , as w ell as the initial v alues f or , , , and . For b oth mo dels , you c an selec t Run ther mal abuse mo del only (ba ttery mo del is tur ned off ) if you w ant to solv e the ener gy equa tion ( Equa tion 24.10 ) alone . Other wise , the t wo ba ttery potential equa tions ( Equa tion 24.11 ) will also b e solv ed. Note •The k inetics par amet ers in ther mal abuse mo dels ar e sp ecific t o the ba ttery ma terial.The default settings ma y not b e appr opriate for y our ba ttery.You must pr ovide par amet er da ta for y our own ba ttery. •For the One-E qua tion ther mal abuse mo del, you c an use the ANSY S Fluen t par amet er estima tion tool available thr ough the TUI t o comput e the k inetics par amet ers fr om the ba ttery oven testing da ta.The en try fields in the MSMD B attery M odel dialo g box will b e aut oma tically popula ted with fitt ed r esults f or the k inetics par amet ers. For details , see Using P aramet er Es- tima tion Tools (p.2396 ). •The ther mal abuse mo del is a vailable only f or the Solving Transp ort Equa tion solution metho d. For mor e inf ormation, see Thermal A buse M odel. 32.3.4.6. Specifying E xternal and Int ernal Shor t-Circuit R esistanc es External Shor t-Circuit To define the e xternal shor t-cir cuit: In the MSMD B attery M odel dialo g box, under the Model Options tab, selec t Specified Resistanc e and sp ecify a v alue f or External Resistanc e. See Specifying B attery Model Options (p.2371 ) for details . 2395Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the D ual-P otential MSMD and C ell N etwork Battery ModelsInternal Shor t-Circuit The in tensit y of the in ternal shor t-cir cuit is det ermined b y the v alue of v olumetr ic contact resistanc e (External and In ternal E lectric Short-Circuit Treatmen t. In the ANSY S Fluen t ba ttery mo del, this value is sa ved in a pr edefined user-defined memor y allo cation, Short Circuit R esistanc e.You c an modify the v alue of this user-defined memor y allo cation t o simula te the in ternal shor t cir cuit. By default , the c ontact resistanc e is set t o a v ery lar ge numb er, so tha t and , tha t is, ther e is no in ternal shor t. You c an simula te an in ternal shor t-cir cuit using either of the f ollowing t wo ways: •Patching : Patch the c ontact resistanc e to the shor t cir cuit z one .The shor t cir cuit z one c an b e defined b y creating a r egion c ell regist er using the Region Regist er dialo g box. See Region in the Fluent U ser's Guide (p.2759 ) for mor e details . •Using UDF : Use DEFINE_ADJUST or DEFINE_ON_DEMAND UDFs to sp ecify the c ontact resistanc e using the UDM macr o,C_UDMI(c,t,SHORT_R) .The c ontact resistanc e could b e a func tion of lo cation and time . See the Fluen t Customiza tion M anual for details . The in ternal shor t-cir cuit mo del is a vailable only f or the Solving Transp ort Equa tion solution metho d. 32.3.5. Using P aramet er E stima tion Tools The par amet ers f or the NT GK, ECM, and one-equa tion ther mal abuse mo dels ar e ba ttery sp ecific . In theor y, the y can b e fitt ed fr om some standar d ba ttery's t esting da ta. ANSY S Fluen t provides par amet er estima tion t ools f or c omputing par amet ers f or these mo dels . The par amet er estima tion t ool can b e acc essed thr ough the t ext-user-in terface (TUI): define/models/battery-model/parameter-estimation-tool Parameter Estimation for Model: 1: NTGK Model 2: ECM Model 3: Thermal Abuse Model Model option: [1] After y ou selec t a mo del option, you will b e pr ompt ed f or inf ormation sp ecific t o the selec ted mo del. Using the par amet er estimation t ool for the NT GK mo del The NT GK mo del par amet ers ar e fitt ed as func tions of DOD and t emp erature.To fit the NT GK mo del paramet ers, you need t o ha ve ba ttery's dischar ging cur ves a t diff erent constan t C-r ates.You c an use testing da ta a t diff erent temp eratures. To use the par amet er estima tion t ool for the NT GK mo del: 1.At the pr ompt , specify Number of temperature levels and Number of discharging curves per temperature level . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2396Modeling B atteries2.For each t emp erature level, enter the t emp erature value and pr ovide files c ontaining t esting da ta at the specified t emp erature. Note The input file or der do es not ma tter. For each C-r ate, you must pr ovide a separ ate file in t ext format. At least t wo input files with da ta at diff erent C-r ates ar e requir ed t o get meaning ful fitting r esults . The file f ormat will b e displa yed in the F luen t console . An example of an input file is sho wn b elow. Crate 1.0 1.0000e+00 4.1097e+00 2.0000e+00 4.1094e+00 3.0000e+00 4.1092e+00 ... 3.6000e+01 4.1010e+00 ... The first line of the file star ts with Crate followed b y a C-r ate value separ ated b y a spac e.The lines tha t follow contain pairs of spac e-separ ated time-v oltage v alues . 3.After you sp ecify input file names f or diff erent C-r ate testing da ta, enter responses t o the f ollowing prompts: •Battery capacity : Specifies c apacit y of the t ested ba ttery. Its value will b e aut oma tically tr ansf erred and displa yed in the Referenc e Capacit y text en try box in the MSMD B attery M odel dialo g box (Model P aramet ers tab). •Number of DOD-levels : Is used in the fitting .The default v alue of 30 DOD le vels is usually sufficien t. If you pr ovide t esting da ta files a t diff erent temp eratures, the par amet er estima tion t ool will p erform the fitting f or each t emp erature level. ANSY S Fluen t will r eport the fitt ed r esults in the c onsole and automa tically pass them in a table da ta type to the par amet er da ta table dialo g boxes.The Table data type will b e aut oma tically selec ted in the MSMD B attery M odel dialo g box (Model P aramet ers tab). This will allo w you t o consider the t emp erature-dep enden t eff ect. If you use t esting da ta fr om only one t emp erature level, the fitting r esults in b oth p olynomial and table da ta types will b e transf erred t o the MSMD B attery M odel dialo g box and t o the par amet er data table dialo g boxes. In this c ase, the Polynomial data type will b e aut oma tically selec ted in the MSMD B attery M odel dialo g box, respectively.You c an use either da ta type in y our simula tion. The f ollowing is an e xample of using the par amet er estima tion t ool for fitting the NT GK mo del par a- met ers: /define/models/battery-model> parameter-estimation-tool Parameter Estimation for Model: 1: NTGK Model 2: ECM Model 3: Thermal Abuse Model Model option: [1] 1 Number of temperature levels: [1] 3 Number of discharging curves per temperature level: [0] 5 -- Make sure every input file has this format -- Crate 1.0 time_1 voltage_1 time_2 voltage_2 2397Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the D ual-P otential MSMD and C ell N etwork Battery Models ... ... ------------------------------------------------ Temperature (K) [300] 300 file name for curve 1 [] ntgk-1C-300K.dat file name for curve 2 [] ntgk-2C-300K.dat file name for curve 3 [] ntgk-3C-300K.dat file name for curve 4 [] ntgk-4C-300K.dat file name for curve 5 [] ntgk-5C-300K.dat Temperature (K) [300] 290 file name for curve 1 [] ntgk-1C-290K.dat file name for curve 2 [] ntgk-2C-290K.dat file name for curve 3 [] ntgk-3C-290K.dat file name for curve 4 [] ntgk-4C-290K.dat file name for curve 5 [] ntgk-5C-290K.dat Temperature (K) [290] 310 file name for curve 1 [] ntgk-1C-310K.dat file name for curve 2 [] ntgk-2C-310K.dat file name for curve 3 [] ntgk-3C-310K.dat file name for curve 4 [] ntgk-4C-310K.dat file name for curve 5 [] ntgk-5C-310K.dat Battery capacity (Ah) [14.6] Number of DOD-levels [30] To help y ou assess and debug the fitting pr ocess, after running the fitting t ool, ANSY S Fluen t aut oma t- ically cr eates a f older c alled fittingresult in y our w orking dir ectory. In this f older , Fluen t stores the f ollowing aut oma tically gener ated files: •ntgk-curve#-t#-crate#.dat : A fitting r esult t ext file with thr ee c olumns of da ta (t,experimental data , and fitting data ) for each C rate cur ve.You c an use this file in a thir d-par ty sof tware for fur ther processing . •ntgk-curve#-t#-crate#.xy : An XY plot file tha t can b e plott ed in F luen t to examine the fitting qualit y. •ntgk-generatepic.scm : A scheme file tha t can b e run in F luen t to dr aw all the gener ated X Y plots and aut oma tically sa ve them as image files . •ntgk-t#-u-function.xy ,ntgk-t#-y-function.xy , and ntgk-t#-intermediate.xy : XY plots of fitt ed U, Y and V~I cur ves. Using the par amet er estimation t ool for the ECM mo del To fit the ECM mo del par amet ers, you need t o ha ve ba ttery's H ybrid P ulse P ower C haracterization (HPPC) t esting da ta a t diff erent SOC le vels. Similar t o the NT GK mo del, you c an use t esting da ta a t different temp eratures. To use the par amet er estima tion t ool for the ECM mo del: 1.At the pr ompt , specify Number of temperature levels and Number of different SOC- level curves per temperature level . 2.For each t emp erature level, enter the t emp erature value and pr ovide files c ontaining t esting da ta at the specified t emp erature. Note The input file or der do es not ma tter. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2398Modeling B atteriesFor each SOC le vel, you must pr ovide a separ ate file with ba ttery's t esting da ta p oints in t ext format. At least one v alid SOC le vel testing da ta is r equir ed p er temp erature level. For go od simula tion results , the r ange of SOC le vels used in the t esting should c over the SOC r ange simula ted in the CFD r uns. The file f ormat will b e displa yed in the F luen t console . An example of an input file is sho wn b elow. SOC 1.0 I 14.6 1.0000e-01 4.2292e+00 2.0000e-01 4.2292e+00 ... 1.1800e+01 4.1041e+00 ... The first line of the file star ts with SOC followed b y a SOC v alue separ ated b y a spac e.The sec ond line c ontains the pulse cur rent inf ormation (I followed b y a pulse cur rent value). The r emaining lines c ontain pairs of spac e-separ ated time-v oltage v alues .The input da ta must include da ta fr om the r est p eriod, the pulse p eriod, and the r elaxa tion p eriod in the t esting . 3.After you sp ecify input file names , enter responses t o the f ollowing pr ompts: •Battery capacity : Specifies c apacit y of the t ested ba ttery. Its value will b e aut oma tically tr ansf erred and displa yed in the Referenc e Capacit y text en try box in the MSMD B attery M odel dialo g box (Model P aramet ers tab). •Circuit Model : –Enter 1 if you w ant to use the 4P par amet er mo del (one R C lo op cir cuit) –Enter 2 if you w ant to use the 6P par amet er mo del (t wo RC lo op cir cuit). •Fitting Method : –Enter 1 if you w ant to use the J iang-Hu metho d The J iang-Hu metho d uses HPPC t esting da ta only fr om the r elaxa tion p eriod. –Enter 2 if you w ant to use the L evenb erg-M arquar dt metho d. The L evenb erg-M arquar dt metho d uses da ta fr om b oth pulse and r elaxa tion p eriods. 4.Although the par amet er estima tion t ool do es not r equir e the t esting ba ttery's c apacit y, you must sp ecify this v alue . If you pr ovide t esting da ta files a t diff erent temp eratures, the par amet er estima tion t ool will p erform the fitting f or each t emp erature level. ANSY S Fluen t will r eport the fitt ed r esults in the c onsole and automa tically pass them in a table da ta type to the par amet er da ta table dialo g boxes.The Table data type will b e aut oma tically selec ted in the MSMD B attery M odel dialo g box (Model P aramet ers tab). This will allo w you t o consider the t emp erature-dep enden t eff ect. If you use t esting da ta fr om only one t emp erature level, the fitting r esults in b oth p olynomial and table da ta types will b e transf erred t o the MSMD B attery M odel dialo g box and t o the par amet er 2399Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the D ual-P otential MSMD and C ell N etwork Battery Modelsdata table dialo g boxes, respectively. In this c ase, the Polynomial data type will b e aut oma tically se- lected in the MSMD B attery M odel dialo g box.You c an use either da ta type in y our simula tion. Note •Because the par amet er estima tion t ool attempts t o calcula te six or f our ECM mo del par amet ers from a non-linear da ta regression pr ocess f or each SOC cur ve, the t esting da ta for each SOC curve should b e sufficien tly lar ge in or der t o obtain a go od fitting . •The par amet er estima tion t ool alw ays fits the e xperimen tal da ta in to either six par amet ers used in the C hen's cir cuit sho wn in Figur e 24.1: Electric Circuits U sed in the ECM M odel or f our par a- met ers in the r educ ed C hen's cir cuit with only one R C lo op. •To obtain optimal fitting of HPPC t esting da ta, you c an tr y diff erent combina tions of the cir cuit model and the fitting metho d.The six-par amet er cir cuit mo del has mor e ph ysics, but the f our- paramet er cir cuit mo del is gener ally mor e robust. As for the fitting metho d, the L evenb erg- Marquar dt algor ithm is in gener al mor e robust than the J iang-Hu algor ithm. You c an star t with the six-par amet er mo del, and then, if the fitting r esults ar e not sa tisfac tory, swit ch to the f our- paramet er mo del. The f ollowing is an e xample of using the par amet er estima tion t ool for fitting the ECM mo del par amet- ers. /define/models/battery-model> parameter-estimation Parameter Estimation for Model: 1: NTGK Model 2: ECM Model 3: Thermal Abuse Model Model option: [2] 2 Number of temperature levels: [3] Number of different SOC-level curves per temperature level: [10] -- Make sure every input file has this format -- SOC 0.6 I 3.153 time_1 voltage_1 time_2 voltage_2 ... ... ------------------------------------------------ where SOC: soc level I: pulse current Temperature (K) [300] 290 file name for curve 1 [] soc01-290K.dat file name for curve 2 [] soc02-290K.dat file name for curve 3 [] soc03-290K.dat file name for curve 4 [] soc04-290K.dat file name for curve 5 [] soc05-290K.dat file name for curve 6 [] soc06-290K.dat file name for curve 7 [] soc07-290K.dat file name for curve 8 [] soc08-290K.dat file name for curve 9 [] soc09-290K.dat file name for curve 10 [] soc10-290K.dat Temperature (K) [290] 300 file name for curve 1 [] soc01-300K.dat file name for curve 2 [] soc02-300K.dat file name for curve 3 [] soc03-300K.dat file name for curve 4 [] soc04-300K.dat file name for curve 5 [] soc05-300K.dat file name for curve 6 [] soc06-300K.dat file name for curve 7 [] soc07-300K.dat file name for curve 8 [] soc08-300K.dat file name for curve 9 [] soc09-300K.dat Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2400Modeling B atteries file name for curve 10 [] soc10-300K.dat Temperature (K) [300] 310 file name for curve 1 [] soc01-310K.dat file name for curve 2 [] soc02-310K.dat file name for curve 3 [] soc03-310K.dat file name for curve 4 [] soc04-310K.dat file name for curve 5 [] soc05-310K.dat file name for curve 6 [] soc06-310K.dat file name for curve 7 [] soc07-310K.dat file name for curve 8 [] soc08-310K.dat file name for curve 9 [] soc09-310K.dat file name for curve 10 [] soc10-310K.dat Battery capacity (Ah) [14.6] 14.6 Circuit Model: 1: 4P parameter model (one RC loop) 2: 6P parameter model (two RC loops) Circuit model option: [2] 2 Fitting Method: 1: Jiang-Hu Method (JH) 2: Levenberg-Marquardt Method (LM) Fitting method option: [2] 2 To help y ou assess and debug the fitting pr ocess, after running the fitting t ool, ANSY S Fluen t aut oma t- ically cr eates a f older c alled fittingresult in y our w orking dir ectory. In this f older , Fluen t stores the f ollowing aut oma tically gener ated files: •ecm-curve#-t#-soc#.dat : A fitting r esult t ext file with thr ee c olumns of da ta (t,experimental data , and fitting data ) for each cur ve.You c an use this file in a thir d-par ty sof tware for fur ther pr o- cessing . •ecm-curve#-t#-soc#.xy : An XY plot file f or each fitting cur ve.You c an plot this file in F luen t and e x- amine the fitting qualit y. •ecm-createpic.scm : A scheme file tha t can b e run in F luen t to dr aw all the gener ated X Y plots and automa tically sa ve them as image files . Using the par amet er estimation t ool for the thermal abuse mo del Kinetics da ta used in the ther mal abuse mo del ar e ba ttery sp ecific . Reaction k inetics par amet ers in Equa tion 24.34 can b e fitt ed b y using t esting da ta (f or e xample , Oven t est or AR C).Temp erature vs. time da ta collec ted fr om e xperimen t for a ba ttery cell under ther mal abuse c ondition c an b e used as input in the par amet er estima tion t ool. The f ollowing ther mal balanc e equa tion is used t o descr ibe the hea ting pr ocess and in the k inetics paramet er fitting of the t emp erature-time da ta: (32.1) wher e: = v olume = e xternal ar ea = ma terial densit y = sp ecific hea t = hea t transf er coefficien t = S tefan-B oltzmann c onstan t 2401Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the D ual-P otential MSMD and C ell N etwork Battery Models = sur face emissivit y = hea t of r eaction = pr e-exponen tial fac tor = ac tivation ener gy = reaction pr ogress v ariable = temp erature = ambien t temp erature = enclosur e temp erature for radia tion and = reaction or der par amet ers The equa tion will b e pr inted in the c onsole f or y our r eference. You will b e pr ompt ed t o sp ecify a file name f or temp erature testing da ta and v alues f or the v ariables used in Equa tion 32.1 (p.2401 ). After running the par amet er estima tion t ool for the one-equa tion ther mal abuse mo del, ANSY S Fluen t will obtain and pass the f ollowing par amet er to the MSMD B attery M odel dialo g box (Advanc ed Option tab): A,E,HW,m, and n.These par amet ers will also b e pr inted in the c onsole . 32.3.6. Initializing the B attery M odel There ar e two ways to initializ e the ba ttery mo del: •Initializ e the flo w field fr om the Solution Initializa tion task page .The ba ttery mo del will b e initializ ed also . •Initializ e the ba ttery mo del in isola tion b y click ing the Init butt on in the MSMD B attery M odel dialo g box. Other flo w variables r emain un touched . Use the sec ond metho d if y ou w ant to freeze the flo w field and use a diff erent ba ttery mo del to simula te the ba ttery field .When swit ching fr om one ba ttery submo del t o another , the ba ttery model must b e re-initializ ed.The Init butt on in the MSMD B attery M odel dialo g box pr ovides a convenien t way to acc omplish this if y ou do not w ant to initializ e the flo w field . 32.3.7. Modifying M aterial P roperties When using the MSMD ba ttery mo dels in ANSY S Fluen t, you must define the UDS diffusivit y of the cell, tab , and busbar ma terials. 32.3.7.1. Specifying UDS D iffusivit y for the A ctive M aterial The UDS diffusivit y of the ac tive ma terial must b e defined using the defined-p er-uds metho d as follows: 1.In the Create/Edit M aterials dialo g box, selec t defined-p er-uds from the dr op-do wn list f or UDS D if- fusivit y. The UDS D iffusion C oefficien ts dialo g box is op ened listing the uds-0 and uds-1 scalar diffusion coefficien ts defined in ANSY S Fluen t. Both sc alars ar e set a t the default v alues of 1e+07 . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2402Modeling B atteries2.Modify the default v alues f or uds-0 and uds-1 (if nec essar y). 3.For anisotr opic ma terial, selec t the orthotr opic ,cyl-or thotr opic , or anisotr opic option fr om the Coef- ficien t drop-do wn list and sp ecify the diffusion c oefficien ts as descr ibed in Fluen t Customiza tion Manual . Note, tha t if the UDS D iffusion C oefficien ts ar e defined thr ough the defined-per-uds option, the F luen t solv er do es not use the v alue f or Electrical C onduc tivit y. 32.3.7.2. Specifying UDS D iffusivit y for the P assiv e M aterial The UDS diffusivit y of the passiv e ma terial must b e defined using user-defined func tions (UDF) as follows: 1.In the Create/Edit M aterials dialo g box, in the Properties group b ox, selec t user-defined from the drop-do wn list f or UDS D iffusivit y. 2.In the User-D efined F unc tions dialo g box, hook the battery_e_cond::lib_caebat predefined func tion pr ovided b y ANSY S Fluen t. Note tha t this func tion c annot b e mo dified . 3.In the Create/Edit M aterials dialo g box, in the Properties group b ox, specify the v alue f or Electrical Conduc tivit y (Fluen t solv er uses this v alue f or the definition of ba ttery_e_c ond). 32.3.7.3. Defining D iffer ent M aterials for P ositiv e and N egativ e Elec trodes If elec tric conduc tivities and are diff erent for the p ositiv e and nega tive elec trodes, you must define t wo diff erent active ma terials, one f or the o dd z ones and another f or the e ven z ones as f ollows: 1.When defining a ma terial for the o dd z ones , in the UDS D iffusion C oefficien ts dialo g box, enter the value of for uds-0 and the v alue of for uds-1 . 2.When defining a ma terial for the e ven z ones , copy the o dd-z one ma terial tha t you ha ve alr eady defined and mo dify the UDS0 and UDS1 sc alars b y interchanging their v alues , tha t is en tering the v alue of for uds-0 and the v alue of for uds-1 . 3.In the Cell Z one C onditions task page , attach the o dd z one ma terial to the o dd z ones , and e ven z one material to the e ven z ones .To det ermine whether a z one b elongs t o the o dd or e ven z one , use the Print Battery System C onnec tion Inf ormation butt on in the Electric C ontacts tab of the MSMD B attery Model dialo g box and r eview the r eport printed in the c onsole windo w. 32.3.8. Solution C ontrols f or the D ual-P otential MSMD B attery M odel When y ou use the ba ttery mo dels , two potential equa tions ar e solv ed in addition t o other fluid d ynamic equa tions , dep ending on the t ype of simula tion. The t wo potential equa tions ( Potential P hi+ and Potential P hi-) are list ed in the Equa tions dialo g box, wher e the y can b e enabled/disabled dur ing the solution pr ocess. Solution → Controls → Equa tions ... Also, if requir ed, define ad vanced settings the Advanc ed S olution C ontrols dialo g box. Setup → Controls → Advanc ed... 2403Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the D ual-P otential MSMD and C ell N etwork Battery Models32.3.9. Postpr ocessing the D ual-P otential MSMD B attery M odel You c an p erform p ostpr ocessing using standar d ANSY S Fluen t quan tities and b y using user-defined scalars and user-defined memor y allo cations .When using the B attery mo del, the f ollowing additional variables will b e available f or p ostpr ocessing: •For the Circuit N etwork solution metho d with the Enable J oule H eat in Tab/Busbar Z ones option: –Under User-D efined Sc alars ... →Voltage F ield →Diff C oef of Voltage F ield –Under User-D efined M emor y... →Volumetic O hmic S our ce (the ener gy sour ce due t o the elec tric Joule hea ting in tab and busbar zones) •For the Solving Transp ort Equa tion and Reduc ed Or der M etho d: –Under User-D efined Sc alars ... →Potential P hi+ →Potential P hi- →Diff C oef of P otential P hi+ →Diff C oef of P otential P hi- –Under User-D efined M emor y... →Transf er C urrent Densit y →X Current Densit y →Y Current Densit y →Z Current Densit y →Magnitude of C urrent Densit y →Volumetr ic O hmic S our ce (the ener gy sour ce due t o the elec tric Joule hea ting) →Total H eat Gener ation S our ce →Cell Voltage →Activation O ver-P otential (the net elec trode p otential change acr oss the ano de and c athode of the system when ther e is a cur rent flo wing thr ough the sy stem, tha t is, (Volts) →Depth of D ischar ge Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2404Modeling B atteries→U Func tion (the NT GK mo del only) →Y Func tion (the NT GK mo del only) →Volumetr ic C urrent Sour ce (the tr ansf er cur rent densit y in Equa tion 24.11 . →X Current Densit y for phi+ →Y Current Densit y for phi+ →Z Current Densit y for phi+ →X Current Densit y for phi- →Y Current Densit y for phi- →Z Current Densit y for phi- →Shor t Circuit Resistanc e (internal shor t cir cuit in tensit y) →Volumetr ic Shor t Current Sour ce (internal shor t cur rent densit y) →Volumetr ic ECHEM C urrent Sour ce (Total e xchange cur rent densit y) →Shor t-Circuit H eat Sour ce (Joule hea t due t o internal shor t cir cuit) →Other Note For reviewing simula tion r esults in CFD P ost f or c ases in volving UDM or UDS, export the solution da ta as CFD-P ost-c ompa tible file (.cdat ) in F luen t and then load this file in to CFD- Post. This will ensur e tha t the full v ariable set is a vailable f or p ost pr ocessing in CFD-P ost. 32.3.10. User-A ccessible F unc tions You c an inc orporate your o wn c orrelations and da ta for the pr operties of the ba ttery using the cae_user.c sour ce code file . The f ollowing listing r epresen ts a descr iption of the c ontents of the cae_user.c sour ce code file: •real CONDUCTIVITY_CELL(cell_t c, Thread *t, int i) : Retur ns v alues f or the elec trical conduc tivit y for cells inside passiv e conduc tive zones , overwriting the v alues set in the Create/Edit M ater- ials dialo g box. •real CONTACT_RESIST_FACE(cell_t f, Thread *t) : Retur ns v alues f or the elec trical contact resistanc e, overwriting the v alues set in the Electric C ontacts tab of the MSMD B attery M odel dialo g box. •real Compute_U (face_t f, Thread *t, real DOD, real dUdJ, real a[], real *dUdJ) : Retur ns v alues f or b oth U and the der ivative of U with r espect to J (dUdJ ). Note tha t DOD represen ts the depth of dischar ge and a[] is the set of U c oefficien ts. 2405Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the D ual-P otential MSMD and C ell N etwork Battery Models•real Compute_Y (face_t f, Thread *t, real DOD, real b[]) : Retur ns v alues f or Y. Note tha t DOD represen ts the depth of dischar ge and b[] is the set of Y coefficien ts. •void Compute_ECM_VOC_and_CR(real soc, real T, int mode, real *Voc, real *RRs, real *RR1, real *RR2, real *CC1, real *CC2) : Retur ns v alues f or ECM mo del-r elated paramet ers.You c an use this func tion t o implemen t ECM par amet ers in an y func tion f orm. •real Compute_OCP_NE(real x, real T) : Retur ns a v alue f or op en cir cuit p otential a t nega tive elec trode ( in Equa tion 24.11 ). By default , it is c omput ed using func tions in 77. •real Compute_OCP_PE(real x, real T) : Retur ns a v alue f or op en cir cuit p otential a t positiv e elec trode ( in Equa tion 24.11 ). By default , it is c omput ed using func tions in 77. •real Compute_kappa(real ce, real T) : Retur ns a v alue f or (Equa tion 24.28 ). By default , it is comput ed using func tions in 77. •real Compute_Diff0_ce(real ce, real T) : Retur ns a v alue f or (Equa tion 24.28 ). By default , it is c omput ed using func tions in 77. •real Compute_tplus(real ce, real T) : Retur ns a v alue f or (Equa tion 24.28 ). By default , it is comput ed using func tions in 77. •real Compute_Ds_PE(real cs, real T ): Retur ns a v alue f or the p ositiv e elec trode diffusion coefficien t (Equa tion 24.21 ). By default , a constan t value fr om GUI input is used . •real Compute_Ds_NE(real cs, real T) : Retur ns a v alue f or the nega tive elec trode diffusion coefficien t (Equa tion 24.21 ). By default , a constan t value fr om GUI input is used . •real Compute_dlnfdlnce(real ce, real T) : Retur ns a v alue f or the t erm from Equa- tion 24.28 . By default , this t erm is not c onsider ed. •void Get_p2d_Postprocessing_Info(cell_t c, Thread *t, real T, real Vp, real Vn) : Exp orts detailed N ewman's P2D mo del r esults . •real Compute_entropy_heat(real soc) : Retur ns the en tropic hea t. By default , it is e xcluded in all MSMD submo dels , but c an b e included it b y defining in this UDF . •void user_defined_echem_model(int zero_start, int mode, real temperature, real voltage, real current, real dtime, real *j_tmp, real *Qe_tmp, real *voltage_end) : Defines the user-defined elec trochemic al mo del. A templa te for the user implemen tation of the NT GK mo del is pr ovided as an e xample . For mor e inf ormation, see the f ollowing sec tions: 32.3.10.1. Compiling the C ustomiz ed B attery Source Code Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2406Modeling B atteries32.3.10.1. Compiling the C ustomiz ed B attery Sour ce Code This sec tion includes instr uctions on ho w to compile a cust omiz ed B attery user-defined mo dule . Imp ortant It is assumed tha t you ha ve a basic familiar ity with c ompiling user-defined func tions (UDFs). For an in troduc tion on ho w to compile UDFs , refer to the separ ate Fluen t Customiza tion Manual . You will first w ant to use a lo cal copy of the msmdbatt directory in the addons directory before you r ecompile the B attery mo dule . 32.3.10.1.1. Compiling the C ustomiz ed S our ce Code Under Linux 1.Make a lo cal copy of the msmdbatt directory. Do not cr eate a symb olic link. Imp ortant The cust om v ersion of the libr ary must b e named acc ording t o the c onvention used by ANSY S Fluen t: for e xample ,msmdbatt . 2.Change dir ectories t o the msmdbatt/src directory. 3.Make changes t o the cae_user.c file. 4.Define the FLUENT_ADDONS environmen t variable t o correspond t o your cust omiz ed v ersion of the Battery mo dule . 5.Change dir ectories t o the msmdbatt/ directory. 6.Issue the f ollowing make command: make FLUENT_INC=[ansys_inc/v195/fluent/fluent19.5.0] FLUENT_ARCH=[arch] -f Makefile-client wher e arch is lnamd64 on LINUX. The f ollowing e xample demonstr ates the st eps r equir ed t o set up and r un a cust omiz ed v ersion of the B attery mo dule tha t is lo cated in a f older c alled home/sample : 1.Make a dir ectory (for e xample ,mkdir -p /home/sample ). 2.Copy the default addon libr ary to this lo cation. cp -RH [ansys_inc/v195/fluent]/fluent19.5.0/addons/msmdbatt /home/sample/msmdbatt 3.Using a t ext edit or, mak e the appr opriate changes t o the cae_user.c file lo cated in /home/sample/msmdbatt/src/cae_user.c 4.Build the libr ary. 2407Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the D ual-P otential MSMD and C ell N etwork Battery Modelscd /home/sample/msmdbatt make FLUENT_INC=[ansys_inc/v195/fluent/fluent19.5.0] FLUENT_ARCH=[arch] -f Makefile-client 5.Set the FLUENT_ADDONS environmen t variable (using CSH, other shells will diff er). setenv FLUENT_ADDONS /home/sample 6.Start ANSY S Fluen t and load the cust omiz ed mo dule using the t ext interface command . 32.3.10.1.2. Compiling the C ustomiz ed S our ce Code Under Windo ws 1.Make a lo cal copy of the msmdbatt folder . Do not cr eate a shor tcut. a.Create a dir ectory for the cust om msmdbatt libr aries (f or e xample ,/home/custom-build ). b.Copy the msmdbatt libr ary from the installa tion of ANSY S Fluen t (Ansys Inc\v195\fluent\flu- ent19.5.0\addons ) to your newly cr eated dir ectory. 2.Open Visual S tudio .NET at the DOS pr ompt. 3.Make sur e tha t the FLUENT_INC environmen t variable is c orrectly set t o the cur rent ANSY S Fluen t in- stalla tion dir ectory (for e xample ,ANSYS Inc\v195\fluent\fluent19.5.0 ). 4.Enter the msmdbatt\src folder . 5.Make changes t o the cae_user.c file. 6.Define the FLUENT_ADDONS environmen t variable t o correspond t o your cust omiz ed v ersion of the Battery mo dule . 7.Retur n to the msmdbatt folder . 8.Issue the f ollowing c ommand in the c ommand windo w: nmake /f makefile_client.nt 9.Define the FLUENT_ADDONS environmen t variable t o correspond t o your cust omiz ed v ersion of the MSMD B attery mo dule in one of f ollowing w ays: •Set the pa th to FLUENT_ADDONS globally . •In the Environmen t tab of F luen t Launcher , enter inf ormation f or FLUENT_ADDONS in the Other Environmen t Variables field , for e xample: FLUENT_ADDONS= :\home\custom-build wher e is the tar get dr ive lett er including the c olon (f or e xample ,D:). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2408Modeling B atteriesChapt er 33: Modeling F uel C ells The ANSY S Fluen t Fuel C ell M odules C hapt er pr ovides inf ormation ab out the back ground and the usage of two separ ate add-on fuel c ell mo dules f or ANSY S Fluen t.The a vailable ANSY S Fluen t add-on fuel c ell modules ar e: •PEMFC M odel - allo ws you t o mo del p olymer elec trolyt e membr ane fuel c ells (PEMFC) with (or without) micr o-porous la yers.This mo del is a new and r ecommended mo del f or simula ting ener gy conversion pr ocesses in a PEM fuel c ell. For mor e inf ormation, see PEMFC M odel Theor y. •Fuel C ell and E lectrolysis M odel - allo ws you t o mo del p olymer elec trolyt e membr ane fuel c ells (PEMFC), solid o xide fuel c ells (SOFC), and elec trolysis with ANSY S Fluen t.This mo del is sometimes r eferred t o as the Resolv ed E lectrolyt e mo del. Note tha t the PEMFC sub-mo del is b eing r etained in the cur rent release . However, it will b e remo ved in futur e releases b ecause the new PEMFC M odel men tioned ab ove is mor e ad vanced and c omplet e as descr ibed in the R elease N otes for ANSY S Fluen t R17.0. For mor e inf ormation, see Fuel C ell and E lectrolysis M odel Theor y. •SOFC With U nresolv ed E lectrolyt e Model - allo ws you t o mo del solid o xide fuel c ells (SOFC). For mor e inf orm- ation, see SOFC F uel C ell With U nresolv ed E lectrolyt e Model Theor y. Additional inf ormation ab out the mo del is pr ovided in the f ollowing sec tions: 33.1. Using the PEMFC M odel 33.2. Using the F uel C ell and E lectrolysis M odel 33.3. Using the S olid O xide F uel C ell With U nresolv ed E lectrolyte Model 33.1. Using the PEMFC M odel The pr ocedur e for setting up and solving fuel c ell pr oblems using the PEMFC mo del is descr ibed in detail in this chapt er. Refer to the f ollowing sec tions f or mor e inf ormation: 33.1.1. Overview and Limita tions 33.1.2. Geometr y Definition f or the PEMFC M odel 33.1.3. Installing the PEMFC M odel 33.1.4. Loading the PEMFC M odule 33.1.5. Workflow for U sing the PEMFC M odule 33.1.6. Setting U p the PEMFC M odule 33.1.7. PEMFC M odel B oundar y Conditions 33.1.8. Solution G uidelines f or the PEMFC M odel 33.1.9. Postpr ocessing the PEMFC M odel 33.1.10. User-A ccessible F unctions 33.1.1. Overview and Limita tions The ANSY S Fluen t PEMFC mo del is c omp osed of se veral user-defined func tions (UDFs) and a gr aphic al user in terface.The p otential fields ar e solv ed as user-defined sc alars .The c apillar y pr essur e, the w ater content (w ater in dissolv ed phase), and liquid sa turation in the gas channels ar e also solv ed as user- defined sc alars .The elec trochemic al reactions o ccur ring in the c atalyst la yers ar e mo deled thr ough 2409Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.various sour ce terms while other mo del par amet ers ar e handled thr ough the user in terface.The PEMFC model c an b e used in par allel ANSY S Fluen t as w ell. Note the f ollowing limita tion when using the PEMFC mo del: •The anisotr opic sp ecies diffusivit y option is not c ompa tible with the PEMFC mo del. 33.1.2. Geometr y Definition f or the PEMFC M odel Due t o the fac t tha t ther e ar e a numb er of diff erent ph ysical zones asso ciated with the fuel c ell, the following r egions must b e pr esen t in the fuel c ell mesh (see Figur e 25.1: Schema tic of a PEM F uel C ell): •Anode flo w channel •Anode gas diffusion la yer •Anode micr o-porous la yer (optional) •Anode c atalyst la yer •Membr ane la yer (solid) •Cathode c atalyst la yer •Cathode micr o-porous la yer (optional) •Cathode gas diffusion la yer •Cathode flo w channel The f ollowing z ones ha ve to be iden tified , if pr esen t in the fuel c ell mesh: •Anode cur rent collec tor (solid) •Cathode cur rent collec tor (solid) •Coolan t channel 33.1.3. Installing the PEMFC M odel The PEMFC mo del is pr ovided as an add-on mo dule with the standar d ANSY S Fluen t licensed sof tware. The mo dule is installed with the standar d installa tion of ANSY S Fluen t in a dir ectory called addons/pem- fc in y our installa tion ar ea.The PEMFC mo dule c onsists of a UDF libr ary and a pr e-compiled Scheme library, which must b e loaded and ac tivated b efore calcula tions c an b e performed . 33.1.4. Loading the PEMFC M odule The PEMFC mo dule is loaded in to ANSY S Fluen t thr ough the t ext user in terface (TUI). The mo dule c an only b e loaded af ter a v alid ANSY S Fluen t case file has b een set or r ead.The t ext command t o load the add-on mo dule is define → models → addon-module A list of ANSY S Fluen t add-on mo dules is displa yed: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2410Modeling F uel C ells> /define/models/addon-module Fluent Addon Modules: 0. None 1. MHD Model 2. Fiber Model 3. Fuel Cell and Electrolysis Model 4. SOFC Model with Unresolved Electrolyte 5. Population Balance Model 6. Adjoint Solver 7. Battery Module 8. MSMD Battery Model 9. PEM Fuel Cell Model Enter Module Number: [0] 9 Selec t the PEM F uel C ell M odel b y en tering the mo dule numb er 9. During the loading pr ocess, a Scheme libr ary (containing the gr aphic al and t ext user in terface) and a UDF libr ary (containing a set of user defined func tions) ar e loaded in to ANSY S Fluen t. 33.1.5. Workflo w for U sing the PEMFC M odule The PEMFC mo del c an b e used t o mo del p olymer elec trolyt e membr ane fuel c ells (PEMFC). The f ollowing descr ibes an o verview of the pr ocedur e requir ed in or der t o use the PEMFC mo del in ANSY S Fluen t. 1.Start ANSY S Fluen t. You must star t ANSY S Fluen t in 3D double-pr ecision mo de. Note tha t the PEMFC mo del is only available in 3D . 2.Read the c ase or mesh file . 3.Scale the mesh, if nec essar y. 4.Use the PEM F uel C ell M odel dialo g box to define the fuel c ell mo del par amet ers. 5.Define ma terial pr operties. 6.Set the op erating c onditions . 7.Set the b oundar y conditions . 8.Start the c alcula tions . 9.Save the c ase and da ta files . 10.Process y our r esults . Imp ortant The PEM F uel C ell M odel dialo g box gr eatly simplifies the input of par amet ers and boundar y conditions , but it do es not r eplac e the b oundar y conditions in terface.Therefore, 2411Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the PEMFC M odelit is a go od policy to star t the setup with the PEM F uel C ell M odel dialo g box and do the finishing st eps f or b oundar y conditions af terwards. Imp ortant Note tha t the major ity of this chapt er descr ibes ho w to set up the ANSY S Fluen t PEMFC model using the gr aphic al user in terface.You c an also p erform v arious tasks using the t ext user in terface. For mor e inf ormation, see Using the PEMFC Text User In terface. 33.1.6. Setting U p the PEMFC M odule Onc e the mo dule has b een loaded , in or der t o set fuel c ell mo del par amet ers and assign pr operties to the r elevant regions in y our fuel c ell, you need t o acc ess the fuel c ell gr aphic al user in terface (the PEM F uel C ell M odel dialo g box). To op en the PEM F uel C ell M odel dialo g box: In the Outline View, under the Models branch, right- click PEM F uel C el and selec t Edit... in the menu tha t op ens. Setup → Models → PEM F uel C ell Edit... Figur e 33.1: The PEMFC Option in the Outline View By default , the PEMFC mo del is enabled . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2412Modeling F uel C ellsUsing the PEM F uel C ell M odel dialo g box, you c an iden tify the r elevant zones f or the cur rent collec tors, flow channels , gas diffusion la yers, micr o porous la yers, catalyst la yers, and the elec trolyt e (membr ane). You c an sp ecify the f ollowing inputs using the PEM F uel C ell M odel dialo g box. Optional inputs ar e indic ated as such. 1.Set the appr opriate options f or the fuel c ell mo del. 2.Set the v arious par amet ers f or the fuel c ell mo del. 3.Selec t the appr opriate zones and sp ecify the pr operties on the ano de side . 4.Selec t the appr opriate zones and sp ecify the pr operties of the elec trolyt e/membr ane. 5.Selec t the appr opriate zones and sp ecify the pr operties on the c athode side . 6.Provide input f or ad vanced f eatures such as c ontact resistivities , coolan t channel pr operties, or stack managemen t settings (optional). 7.Set solution c ontrols such as under-r elaxa tion fac tors (optional). 8.Provide input t o assist r eporting (optional). Refer to the f ollowing sec tions f or mor e inf ormation: 33.1.6.1. Specifying M odel Options (M odel Tab) 33.1.6.2. Specifying M odel P aramet ers (P aramet ers Tab) 33.1.6.3. Specifying A node P roperties (A node Tab) 33.1.6.4. Specifying E lectrolyte/M embr ane P roperties (E lectrolyte Tab) 33.1.6.5. Specifying C athode P roperties (C athode Tab) 33.1.6.6. Setting A dvanced P roperties (A dvanced Tab) 33.1.6.7. Reporting on the S olution (R eports Tab) 33.1.6.1. Specifying Mo del O ptions ( Mo del Tab) The Model tab of the PEM F uel C ell M odel dialo g box allo ws you t o selec t or c ancel the selec tion of v arious options when solving a fuel c ell pr oblem. 2413Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the PEMFC M odelFigur e 33.2: The M odel Options in the PEM F uel C ell M odel D ialo g Box Options Several fuel c ell mo del options ar e available including: Joule H eating takes in to acc oun t ohmic hea ting .This option includes the terms in the ener gy sour ce term in the calcula tions . See Table 25.1: Volumetr ic Heat Source Terms for the list of additional v olumetr ic sour ces in the ther mal ener gy equa tion. Reac tion H eating takes in to acc oun t the hea t gener ated b y the elec trochemic al reactions . Electrochemistr y Sour ces allows the PEMFC mo del t o tak e elec trochemistr y eff ects in to acc oun t. If you ar e only in terested in the basic flo w field thr oughout the fuel c ell, you c an tur n off the Electrochemistr y Sour ces option in or der to suppr ess most eff ects of the PEMFC mo del. You ma y also tur n off the eff ect of these sour ces in or der to obtain a fluid flo w initially , and then tur n it back on. Butler-V olmer R ate (the default) is used t o comput e the tr ansf er cur rents inside the c atalyst la yers. If this option is tur ned off, the Tafel appr oxima tion ( Equa tion 25.7 and Equa tion 25.8 ) is used . Liquid P hase takes in to acc oun t liquid phase c alcula tions . Use this option if y ou ar e solving f or liquid tr ansp ort in the fuel c ell. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2414Modeling F uel C ellsMultic omp onen t Diffusion is used t o comput e the gas sp ecies mass diffusivit y using the full multic omp onen t diffusion metho d as descr ibed in Equa tion 25.40 , as opp osed t o the default option tha t uses Equa tion 25.38 . Anisotr opic E-C ond . in P orous E lectrode is used t o mo del the t ypic ally non-isotr opic elec trical conduc tivit y. It is applic able only f or p orous elec- trodes (gas diffusion la yers and micr o porous la yers). Due t o the fibr ous str ucture of the p orous ma terial tha t is used f or the elec trodes (or gas diffusion layer), the elec trical conduc tivit y is t ypic ally non-isotr opic al, with the cr oss-plane c omp onen ts being or ders of magnitude smaller than the in-plane c omp onen ts.This c an b e mo deled using the Anisotr opic E-C onduc tivit y in P orous E lectrode setting .When this option is enabled , the Electrical C onduc tivit y for the solid ma terial used in the p orous elec trodes is no longer used . Instead, you need t o sp ecify , for this solid ma terial, the elec trical conduc tivit y by cho osing one of the thr ee non-isotr opic al options f or the UDS diffusivit y (UDS-0 ).The thr ee options ar e:aniso- tropic ;orthotr opic ; and cyl-or thotr opic . For mor e inf ormation ab out these UDS D iffusivit y options , refer to the ANSY S Fluen t User's G uide (p.1). For e xample , to use this f eature, perform the f ollowing st eps: •Selec t the Anisotr opic E-C onduc tivit y in P orous E lectrode option in the Model tab of the PEM F uel Cell M odel dialo g box. •In the Create/Edit M aterials dialo g box, selec t defined-per-uds for UDS D iffusivit y for the solid material tha t is t o be used f or the p orous elec trode. •Selec t one of the thr ee options f or UDS-0: anisotr opic ;orthotr opic ; or cyl-or thotr opic and set the appr opriate values . Imp ortant Note tha t, in this c ase, the Electrical C onduc tivit y for this solid ma terial is ignor ed. Effective P-C ond . in MEA enables the c omputa tion of the elec trolyt e phase c onduc tivit y with c onsider ation of ionomer volume fr action and t ortuosit y in the c atalyst la yers using Equa tion 25.41 . If this option is disabled , then and . Use H alf-C ell P otentials enables the c alcula tions of the ano de and c athode half-c ell p otentials and using the N ernst equa tions ( Equa tion 25.13 and Equa tion 25.14 ). If this option is disabled , the c onstan t op en-cir cuit v oltage is assumed , and the and are set t o zero. Catho de P article M odel enables the c athode par ticle mo del. For inf ormation ab out this mo del, see The C athode P article M odel. Liquid P hase enables the liquid w ater tr ansp ort equa tions in the c omputa tions . By default , this option is enabled . 2415Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the PEMFC M odelComput e Liquid in C hannels enables the solution of the liquid sa turation equa tion in the gas channels . By default , this option is dis- abled , and the equa tion is not solv ed. Include D ynamic H ead (if enabled) includes the d ynamic pr essur e in the gas channel in Equa tion 25.32 . W-Diff Mo del You c an selec t one of the f ollowing f ormula tions f or the func tion in Equa tion 25.43 : Wu comput es using Wu's f ormula tion ( Equa tion 25.44 ). Wang comput es using Wang's f ormula tion ( Equa tion 25.45 ). Under -Relaxation F actors You c an use the Under-Relaxa tion F actors fields t o influenc e the solution pr ocess. Liquid-V apor The sour ce term in Equa tion 25.30 usually r equir es under-r elaxa tion. Since the is comput ed e xpli- citly as a sour ce term for the c apillar y pr essur e equa tion ( Equa tion 25.30 ), the under-r elaxa tion fac tor usually must b e a small v alue in or der t o obtain c onvergenc e.You c an change the default v alue f or the under-r elaxa tion fac tor b y changing the v alue f or Liquid-V apor. Disv’d-V apor/Liquid The sour ce terms and in Equa tion 25.22 usually r equir e under-r elaxa tion also .You c an change the default v alue f or the under-r elaxa tion fac tor b y changing the v alue f or Disv’d-V apor/Liquid . Osmotic D rag S our ce You c an also sp ecify an under-r elaxa tion fac tor for the osmotic dr ag t erm, namely the lef t-hand side term of Equa tion 25.22 by changing the v alue f or Osmotic D rag S our ce. GDL Liquid Remo val The liquid w ater flux tha t go es out of the gas diffusion la yer (GDL) a t the GDL-C hannel in terface (Equa- tion 25.32 ) can also b e under-r elax ed using GDL Liquid Remo val. Automatic S ettings The f ollowing par allel multigr id solv er control par amet er is a vailable: F-cycle f or A ll Equa tions sets the multigr id cycle t ype to F c ycle f or all equa tions tha t are being solv ed.This c ontrol overrides the equa tion c ycle settings in the Advanc ed S olution C ontrols dialo g box. Note Using F-c ycle f or PEMFC c omputa tions is the b est pr actice appr oach. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2416Modeling F uel C ells33.1.6.2. Specifying Mo del P aramet ers ( Paramet ers Tab) You c an use the Paramet ers tab of the PEM F uel C ell M odel dialo g box to sp ecify the elec trochemistr y paramet ers f or the PEMFC mo del, reference diffusivities f or the r eactants and other mo del par amet ers. Figur e 33.3: The P aramet ers Tab of the PEM F uel C ell M odel D ialo g Box Elec trochemistr y There ar e various par amet ers under Electrochemistr y in the PEM F uel C ell M odel dialo g box. For both the ano de and the c athode, you c an set the f ollowing par amet ers or lea ve the default v alues: J_ref corresponds t o and , the r eference exchange cur rent densit y from Equa tion 25.9 and Equa- tion 25.10 . C_ref corresponds t o the r eference concentration ( and ) with units of 1 k gmol/m3 (see Equa- tion 25.5 and Equa tion 25.6 ). Con. Exponen t corresponds t o , the c oncentration dep endenc e from Equa tion 25.5 . Exch. Coeff. (a) ,Exch. Coeff. (c) are the tr ansf er coefficien ts and from Equa tion 25.5 and Equa tion 25.6 , respectively. 2417Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the PEMFC M odelStd. State E0 are the r eversible p otentials and in Equa tion 25.13 and Equa tion 25.14 , respectively.This field app ears only when Use H alf-C ell P otentials option is selec ted under the Model tab . Entropy is the r eaction en tropy and in Equa tion 25.13 and Equa tion 25.14 . V_Op en corresponds t o the c onstan t value assigned t o cathode half-c ell p otential and .This par amet er app ears only when Use H alf-C ell P otentials option is not selec ted under the Model tab . I_leak is the leak age cur rent densit y (A/m2). It is used t o comput e the t otal leak age cur rent (in Equa tion 25.48 through Equa tion 25.50 ) by: wher e is the elec trolyt e pr ojec ted ar ea (sp ecified under the Rep orts tab). When leak age thr ough the elec trolyt e occurs , the fuel c ell gener ates less cur rent esp ecially f or c ases with lo w values of fuel or air utiliza tion. Note tha t you c an also sp ecify the t otal leak age cur rent thr ough the user- defined func tion Leakge_Current() . For mor e inf ormation, see User-A ccessible F unc- tions (p.2439 ). Std.Temp . for U0 (K) is the r eference standar d sta te temp erature which is used f or half-c ell p otentials c omputa tions in the Nernst equa tions ( Equa tion 25.13 and Equa tion 25.14 ).This par amet er app ears only when the Use H alf- Cell P otentials option is selec ted under the Model tab . Std. Press. for U0 (P a) is the r eference standar d sta te pr essur e which is used f or half-c ell p otentials c omputa tions in the N ernst equa tions ( Equa tion 25.13 and Equa tion 25.14 ).This par amet er app ears only when the Use H alf-C ell Potentials option is selec ted under the Model tab . Note The default v alues of the mo del par amet ers ar e det ermined based on v arious da ta a vailable in the lit erature (413,442,586 632, and others). Refer enc e Diffusivit y The par amet ers in the Referenc e D iffusivit y group b ox app ear only if the Multic omp onen t Diffusion option is tur ned off in the Model tab .These par amet ers c orrespond t o the sp ecies mass diffusivit y from Equa tion 25.38 . Liquid P hase When the Liquid P hase option is selec ted under the Model tab , you c an sp ecify the f ollowing par a- met ers tha t app ear in the Liquid P hase group b ox: Expon’t Diff_gas corresponds t o from Equa tion 25.38 for multiphase PEMFC c alcula tions . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2418Modeling F uel C ellsExpon’t J_r ef is the e xponen t tha t is used t o mo dify and acc ording t o Equa tion 25.35 to acc oun t for liquid blockage t o the r eaction sur face in Equa tion 25.5 through Equa tion 25.8 . Expon’t K_r el is the e xponen t tha t is used t o comput e the r elative permeabilit y in (Equa tion 25.28 ). Expon’t Liq_c overage is the e xponen t tha t is used t o comput e the phase-change r ates and (Equa tion 25.23 and Equa tion 25.24 ). Liq.-Disv’ed P hase is the mass e xchange r ate constan t tha t is used t o comput e the r ate of mass change b etween liquid and dissolv ed phases (Equa tion 25.24 ). Liquid D ensit y,Liq.Thermal C ond . are the densit y and ther mal c onduc tivit y of liquid w ater, respectively. Note tha t the eff ective ther mal conduc tivit y in p orous media is c omput ed as: (33.1) Liq. Diff. in C han. is the in Equa tion 25.36 .This par amet er app ears only when the Comput e Liquid In C hannel option is selec ted under the Model tab . V_liq/V_gas in C han. is the liquid t o gas v elocity ratio in the channel ( in Equa tion 25.36 ).This par amet er app ears only when the Comput e Liquid In C hannel option is selec ted under the Model tab . Other P aramet ers Under Other P aramet ers, you c an sp ecify the f ollowing: Gas-D isv’ed P hase is the mass e xchange r ate constan t tha t is used t o comput e the r ate of mass change b etween gas and dissolv ed phases (Equa tion 25.23 ). Mod. Coef. OSM_dr ag is the c onstan t with the default v alue of 1.0 tha t is used t o gener alize the default osmotic dr ag coefficien t (Equa tion 25.46 ). Eq.W. Cont. at a=1 is the equilibr ium w ater content at the w ater ac tivit y of 1, , tha t is used in c omputing the equilibr ium water content (Equa tion 25.25 ). Eq.W. Cont. at s=1 is the equilibr ium w ater content at water sa turation of 1, , tha t is used in c omputing the equilibr ium water content (Equa tion 25.25 ).This it em app ears only if the Liquid P hase option is selec ted under the Model tab . 2419Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the PEMFC M odel33.1.6.3. Specifying A node P roperties ( AnodeTab) You c an use the Anode tab of the PEM F uel C ell M odel dialo g box to sp ecify z ones and pr operties of the cur rent collec tor, the flo w channel, the diffusion la yer, the micr o porous la yer (optional), and the c atalyst la yer for the ano de p ortion of the fuel c ell. 33.1.6.3.1. Specifying C urrent C ollec tor P roperties for the A node Figur e 33.4: The A node Tab of the PEM F uel C ell M odel D ialo g Box with C urrent Collec tor Selec ted 1.Under Anode Z one Type, selec t Current Collec tor. 2.From the Zone(s) selec tion list , selec t a c orresponding z one . If you ar e mo deling a fuel c ell stack, then you must selec t all zones of a par ticular t ype as a gr oup . 3.From the Solid M aterial drop-do wn list , selec t the appr opriate ma terial.You c an use the Create/Edit Materials dialo g box to cust omiz e solid ma terials. Note tha t for the Electrical C onduc tivit y, you c an only selec t a c onstan t value in the Create/Edit M aterials dialo g box.The solid elec trical conduc tivit y value is the diffusivit y of the solid phase p otential in the solid z ones . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2420Modeling F uel C ells33.1.6.3.2. Specifying F low C hannel P roperties for the A node Figur e 33.5: The A node Tab of the PEM F uel C ell M odel D ialo g Box with F low C hannel S elec ted 1.Under Anode Z one Type, selec t Flow C hannel . 2.From the Zone(s) selec tion list , selec t an appr opriate zone . 2421Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the PEMFC M odel33.1.6.3.3. Specifying P orous Elec trode P roperties for the A node Figur e 33.6: The A node Tab of the PEM F uel C ell M odel D ialo g Box with P orous E lectrode Selec ted 1.Under Anode Z one Type, selec t Porous E lectrode. 2.From the Zone(s) selec tion list , selec t a c orresponding z one . If you ar e mo deling a fuel c ell stack, then you must selec t all zones of a par ticular t ype as a gr oup . 3.From the Solid M aterial drop-do wn list , selec t the appr opriate ma terial.You c an use the Create/Edit Materials dialo g box to cust omiz e solid ma terials. Note tha t for the Electrical C onduc tivit y, you c an only selec t a c onstan t value in the Create/Edit M aterials dialo g box.The solid elec trical conduc tivit y value is the diffusivit y of the solid phase p otential in the solid z ones . 4.Specify v alues f or the f ollowing par amet ers: Porosit y is in Equa tion 25.38 . Absolut e Permeabilit y is in Equa tion 25.27 . H-phobic C ontact Angle hydrophobic c ontact angle in Equa tion 25.33 . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2422Modeling F uel C ellsWater Remo val C oef. in Equa tion 25.32 . Leverett F unc . Coeff_a is the L everett func tion c oefficien t in Equa tion 25.34 (default = 1.417). Leverett F unc . Coeff_b is the L everett func tion c oefficien t in Equa tion 25.34 (default = 2.12). Leverett F unc . Coeff_c is the L everett func tion c oefficien t in Equa tion 25.34 (default = 1.263). Condensa tion R ate Coeff. in Equa tion 25.31 Evaporation R ate Coeff. in Equa tion 25.31 33.1.6.3.4. Specifying C atal yst L ayer P roperties for the A node Figur e 33.7: The A node Tab of the PEM F uel C ell M odel D ialo g Box with TPB L ayer (C ataly st) Selec ted 2423Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the PEMFC M odel1.Under Anode Z one Type, selec t TPB L ayer (C ataly st). 2.From the Zone(s) selec tion list , selec t a c orresponding z one . If you ar e mo deling a fuel c ell stack, then you must selec t all zones of a par ticular t ype as a gr oup . 3.From the Solid M aterial drop-do wn list , selec t the appr opriate ma terial.You c an use the Create/Edit Materials dialo g box to cust omiz e solid ma terials. Note tha t for the Electrical C onduc tivit y, you c an only selec t a c onstan t value in the Create/Edit M aterials dialo g box.The solid elec trical conduc tivit y value is the diffusivit y of the solid phase p otential in the solid z ones . 4.Specify v alues f or the f ollowing par amet ers: Porosit y is in Equa tion 25.38 . Absolut e Permeabilit y is in Equa tion 25.27 . Surface/Volume R atio is the sp ecific ac tive sur face area in Equa tion 25.5 . H-phobic C ontact Angle is the h ydrophobic c ontact angle in Equa tion 25.33 . Protonic C onduc tion C oefficien t is the mo del c onstan t in Equa tion 25.42 (available only when the Effective P-C onduc tivit y in MEA option is selec ted under the Model tab). Protonic C onduc tion E xponen t is the mo del c onstan t in Equa tion 25.41 (available only when the Effective P-C onduc tivit y in MEA option is selec ted under the Model tab). Ionomer Tortuosit y is the in Equa tion 25.42 (available only when the Effective P-C onduc tivit y in MEA option is se- lected under the Model tab). Ionomer Volume F raction is the in Equa tion 25.42 (available only when the Effective P-C onduc tivit y in MEA option is se- lected under the Model tab). Activation E nergy for P-C ond is the in Equa tion 25.41 (available only when the Effective P-C onduc tivit y in MEA option is se- lected under the Model tab). Activation E nergy for J_r ef is the in Equa tion 25.9 . Referenc e Temp erature Temp erature for J_r ef is the in Equa tion 25.9 . Leverett F unc . Coeff_a is the L everett func tion c oefficien t in Equa tion 25.34 (default = 1.417). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2424Modeling F uel C ellsLeverett F unc . Coeff_b is the L everett func tion c oefficien t in Equa tion 25.34 (default = 2.12). Leverett F unc . Coeff_c is the L everett func tion c oefficien t in Equa tion 25.34 (default = 1.263). Condensa tion R ate Coeff. in Equa tion 25.31 Evaporation R ate Coeff. in Equa tion 25.31 33.1.6.3.5. Specifying M icro Porous L ayer (O ptional) P roperties for the A node Figur e 33.8: The A node Tab of the PEM F uel C ell M odel D ialo g Box with M icro Porous L ayer Selec ted 1.Under Anode Z one Type, selec t Micro Porous L ayer. 2.From the Zone(s) selec tion list , selec t a c orresponding z one . If you ar e mo deling a fuel c ell stack, then you must selec t all zones of a par ticular t ype as a gr oup . 3.From the Solid M aterial drop-do wn list , selec t the appr opriate ma terial.You c an use the Create/Edit Materials dialo g box to cust omiz e solid ma terials. Note tha t for the Electrical C onduc tivit y, you c an only selec t a c onstan t value in the Create/Edit M aterials dialo g box.The solid elec trical conduc tivit y value is the diffusivit y of the solid phase p otential in the solid z ones . 2425Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the PEMFC M odel4.Specify v alues f or the f ollowing par amet ers: Porosit y is in Equa tion 25.38 . Absolut e Permeabilit y is in Equa tion 25.27 . H-phobic C ontact Angle hydrophobic c ontact angle in Equa tion 25.33 . Leverett F unc . Coeff_a is the L everett func tion c oefficien t in Equa tion 25.34 (default = 1.417). Leverett F unc . Coeff_b is the L everett func tion c oefficien t in Equa tion 25.34 (default = 2.12). Leverett F unc . Coeff_c is the L everett func tion c oefficien t in Equa tion 25.34 (default = 1.263). Condensa tion R ate Coeff. in Equa tion 25.31 Evaporation R ate Coeff. in Equa tion 25.31 33.1.6.3.6. Specifying C ell Z one C onditions for the A node For each c ase of the ano de’s cur rent collec tor, diffusion la yer, micr o porous la yer, and c atalyst la yer, you assign a solid ma terial and/or set the p orosity and the visc ous r esistanc e.These settings r epresen t setting a c ell z one c ondition. With the Update Cell Z ones option tur ned on (the default setting), this c ell z one c ondition is applied t o all selec ted z ones in the Zone(s) list. If you w ant to set the c ell zone c onditions f or each z one individually (using the Cell Z one C onditions task page), you should turn off the Update Cell Z ones option. 33.1.6.4. Specifying Elec trolyte/Membr ane P roperties ( Elec trolyteTab) You c an use the Electrolyt e tab of the PEM F uel C ell M odel dialo g box to sp ecify z ones and pr operties of the elec trolyt e/membr ane p ortion of the fuel c ell. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2426Modeling F uel C ellsFigur e 33.9: The E lectrolyt e Tab of the PEM F uel C ell M odel D ialo g Box 1.From the Zone(s) selec tion list , selec t a c orresponding z one . If you ar e mo deling a fuel c ell stack, then you must selec t all zones of a par ticular t ype as a gr oup . 2.From the Solid M aterial drop-do wn list , selec t the appr opriate ma terial.You c an use the Create/Edit Materials dialo g box to cust omiz e solid ma terials. 3.Specify v alues f or the f ollowing par amet ers: Equiv alen t Weigh t is the in Equa tion 25.23 and Equa tion 25.24 . Protonic C onduc tion C oefficien t is the in Equa tion 25.42 . Protonic C onduc tion E xponen t is the in Equa tion 25.41 . Water D iffusivit y Coefficien t is the in Equa tion 25.43 . Activation E nergy for P-C ond is the in Equa tion 25.41 (available only when the Effective P-C onduc tivit y in MEA option is se- lected under the Model tab). 2427Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the PEMFC M odelAbsolut e Permeabilit y is the in Equa tion 25.27 . Note tha t the PEMFC mo del allo ws you t o mo del the elec trolyt e/membr ane as a solid z one only . However, it still allo ws for dissolv ed w ater, liquid or c apillar y pr essur e, and the ionic cur rent to pass through. 33.1.6.4.1. Specifying C ell Z one C onditions for the Membr ane When y ou assign a solid ma terial t o the membr ane, you ar e setting a c ell z one c ondition. With the Update Cell Z ones option tur ned on (the default setting), this c ell z one c ondition is applied t o all selec ted z ones in the Zone(s) list. If you w ant to set the c ell z one c onditions f or each z one individually (using the Cell Z one C onditions task page), you should tur n off the Update Cell Z ones option. 33.1.6.5. Specifying C atho de P roperties ( Catho deTab) You c an use the Catho de tab of the PEM F uel C ell M odel dialo g box to sp ecify z ones and pr operties of the cur rent collec tor, the flo w channel, the diffusion la yer, the micr o porous la yer, and the c atalyst layer for the c athode p ortion of the fuel c ell. 33.1.6.5.1. Specifying C urrent C ollec tor P roperties for the C atho de The pr ocedur e for sp ecifying the cur rent collec tor pr operties f or the c athode is similar t o tha t for the ano de. For sp ecific st eps, refer to Specifying C urrent Collec tor P roperties f or the A node (p.2420 ) for details and then substitut e “cathode” for “ano de” wher e appr opriate. 33.1.6.5.2. Specifying F low C hannel P roperties for the C atho de The pr ocedur e for sp ecifying the flo w channel pr operties f or the c athode is similar t o tha t for the ano de. For sp ecific st eps, refer to Specifying F low C hannel P roperties f or the A node (p.2421 ) and then substitut e “cathode” for “ano de” wher e appr opriate. 33.1.6.5.3. Specifying P orous Elec trode P roperties for the C atho de The pr ocedur e for sp ecifying the p orous elec trode pr operties f or the c athode is similar t o tha t for the ano de. For sp ecific st eps, refer to Specifying P orous E lectrode P roperties f or the A node (p.2422 ) and then substitut e “cathode” for “ano de” wher e appr opriate. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2428Modeling F uel C ells33.1.6.5.4. Specifying C atal yst L ayer P roperties for the C atho de Figur e 33.10: The C atho de Tab of the PEM F uel C ell M odel D ialo g Box with TPB L ayer (C ataly st) Selec ted 1.Under Catho de Z one Type, selec t TPB L ayer (C ataly st). 2.From the Zone(s) selec tion list , selec t a c orresponding z one . If you ar e mo deling a fuel c ell stack, then you must selec t all zones of a par ticular t ype as a gr oup . 3.From the Solid M aterial drop-do wn list , selec t the appr opriate ma terial.You c an use the Create/Edit Materials dialo g box to cust omiz e solid ma terials. Note tha t for the Electrical C onduc tivit y, you c an only selec t a c onstan t value in the Create/Edit M aterials dialo g box.The solid elec trical conduc tivit y value is the diffusivit y of the solid phase p otential in the solid z ones . 4.Specify v alues f or the f ollowing par amet ers: Porosit y is in Equa tion 25.38 . Absolut e Permeabilit y is in Equa tion 25.27 . 2429Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the PEMFC M odelSurface/Volume R atio is the sp ecific ac tive sur face area in Equa tion 25.6 . H-phobic C ontact Angle is the h ydrophobic c ontact angle in Equa tion 25.33 . Protonic C onduc tion C oefficien t is the mo del c onstan t in Equa tion 25.42 (available only when the Effective P-C onduc tivit y in MEA option is selec ted under the Model tab). Protonic C onduc tion E xponen t is the mo del c onstan t in Equa tion 25.41 (available only when the Effective P-C onduc tivit y in MEA option is selec ted under the Model tab). Ionomer Tortuosit y is the in Equa tion 25.42 (available only when the Effective P-C onduc tivit y in MEA option is se- lected under the Model tab). Ionomer Volume F raction is the in Equa tion 25.42 (available only when the Effective P-C onduc tivit y in MEA option is se- lected under the Model tab). Activation E nergy for P-C ond is the in Equa tion 25.41 (available only when the Effective P-C onduc tivit y in MEA option is se- lected under the Model tab). Activation E nergy for J_r ef is the in Equa tion 25.10 . Referenc e Temp erature for J_r ef is the in Equa tion 25.10 . Besides the par amet ers f or the c atalyst la yer list ed ab ove, you c an also sp ecify the f ollowing paramet ers f or The C athode P article M odel: Prod. Of O2 S olubilit y and D iffusivit y is in Equa tion 25.16 . Radius of C ataly st P article is in Equa tion 25.16 . Catho de I onomer Resistanc e is in Equa tion 25.15 . 33.1.6.5.5. Specifying M icro Porous L ayer (O ptional) P roperties for the C atho de The pr ocedur e for sp ecifying the c atalyst la yer pr operties f or the c athode is similar t o tha t for the ano de. For sp ecific st eps, refer to Specifying M icro Porous La yer (Optional) P roperties f or the A n- ode (p.2425 ) and then substitut e “cathode” for “ano de” wher e appr opriate. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2430Modeling F uel C ells33.1.6.5.6. Specifying C ell Z one C onditions for the C atho de For each c ase of the c athode’s cur rent collec tor, diffusion la yer, micr o porous la yer, and c atalyst layer, you assign a solid ma terial and/or set the p orosity and the visc ous r esistanc e.These settings represen t setting a c ell z one c ondition. With the Update Cell Z ones option tur ned on (the default setting), this c ell z one c ondition is applied t o all selec ted z ones in the Zone(s) list. If you w ant to set the c ell z one c onditions f or each z one individually (using the Cell Z one C onditions task page), you should tur n off the Update Cell Z ones option. 33.1.6.6. Setting A dvanc ed P roperties ( Advanc edTab) You c an use the Advanc ed tab of the PEM F uel C ell M odel dialo g box to sp ecify the c ontact resistivit y for an y ma terial in terface in the geometr y, set par amet ers f or c oolan t channels , and define fuel stack units f or managing stacks of fuel c ells. 33.1.6.6.1. Setting C ontac t Resistivities for the P EMFC Mo del Figur e 33.11: The A dvanc ed Tab of the PEM F uel C ell M odel D ialo g Box for C ontact Resistivities 1.Under Advanc ed S etup , selec t Contact Resistivit y. 2431Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the PEMFC M odel2.From the Available Z one(s) selec tion list , selec t an y numb er of c orresponding in terfaces.These z ones are fac e zones o ver which a jump in elec trical potential is c aused b y imp erfect conduc tion. Note The c ontact resistanc e will b e applied only t o wall and porous jump types of in- terfaces. 3.Specify a v alue f or the Resistivit y for each sp ecified z one . Note tha t at porous jump and w all/w all-shado w in terfaces, the c ontact resistivit y is applied a t each fac e.Therefore, you need t o sp ecify the r esistivit y only a t one of the in terface walls, other wise the ac tual r esistanc e will b e doubled a t the in terface. 4.To simplify the input , you c an cho ose t o use the r esistivit y value of the first selec ted z one f or all others as w ell b y selec ting the Use F irst Value f or A ll option. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2432Modeling F uel C ells33.1.6.6.2. Setting C oolant C hannel P roperties for the P EMFC Mo del (O ptional) Figur e 33.12: The A dvanc ed Tab of the PEM F uel C ell M odel D ialo g Box for the C oolan t Channel 1.Under Advanc ed S etup , selec t Coolan t Channel . 2.From the Zone(s) selec tion list , selec t an y numb er of c orresponding z ones . 3.Specify a v alue f or the Coolan t Densit y. 4.To enable the c oolan t channel, selec t the Enable C oolan t Channel(s) option. Amongst other settings , this will aut oma tically cr eate a new mix ture ma terial pem+cool-mixture consisting of hydrogen , oxygen ,water-vapor ,coolant-liquid , and nitrogen . 5.Using the Create/Edit M aterials dialo g box, set all other ma terial pr operties f or the new fluid coolant- liquid . 6.Specify the inlet and outlet c onditions f or cooling channels using standar d boundar y conditions dialo g boxes. 2433Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the PEMFC M odel33.1.6.6.3. Managing Stacks for the P EMFC Mo del Figur e 33.13: The A dvanc ed Tab of the PEM F uel C ell M odel D ialo g Box for S tack M anagemen t The ANSY S Fluen t PEMFC mo del allo ws you t o mo del fuel c ell stacks as w ell as individual fuel c ells. In the Advanc ed tab of the PEM F uel C ell M odel dialo g box, you c an define fuel c ell units for each fuel c ell in a stack. A fuel c ell unit c onsists of all z ones of a single fuel c ell in the stack. Imp ortant If you ar e only mo deling a single fuel c ell, then y ou do not need t o set an ything f or Stack Managemen t in the Advanc ed tab of the PEM F uel C ell M odel dialo g box. 1.Selec t the Advanc ed tab of the PEM F uel C ell M odel dialo g box. 2.Selec t Stack M anagemen t under Advanc ed S etup . 3.Since a fuel c ell unit c onsists of all z ones of a single fuel c ell in the stack, selec t the c orresponding z ones from the Zone(s) list. 4.Create a new fuel c ell unit b y click ing the Create butt on.The new fuel c ell is list ed under Fuel C ell Unit(s) with a default name . 5.Edit a pr e-existing fuel c ell unit b y selec ting it in the Fuel C ell U nit(s) list. The z ones in this fuel c ell unit are aut oma tically selec ted in the Zone(s) list. You c an then mo dify the z ones tha t mak e up the fuel c ell unit and/or change its name in the Name field and click Modify to sa ve the new settings . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2434Modeling F uel C ells6.Remo ve a pr e-existing fuel c ell unit b y selec ting it in the Fuel C ell U nit(s) list and click ing the Delet e butt on. Note When deleting a unit , mak e sur e tha t the elec trical connec tivit y remains in tact. 7.If your mo del c ontains man y zone names , you c an use the Match Z one N ame P attern field t o sp ecify a pa ttern to look for in the names of z ones .Type the pa ttern in the t ext field and click Match to selec t (or deselec t) the z ones in the Zones list with names tha t ma tch the sp ecified pa ttern.You c an ma tch additional char acters using * and ?. For e xample , if you sp ecify wall* , all sur faces whose names b egin with wall (for e xample ,wall-1 ,wall-t op) will b e selec ted aut oma tically. If the y are all selec ted alr eady, they will b e deselec ted. If you sp ecify wall? , all sur faces whose names c onsist of wall followed b y a single char acter will b e selec ted (or deselec ted, if the y are all selec ted alr eady). For e xample , in a stack ther e ar e man y fuel c ells, say 10–100, each ha ving a t least 9 z ones (cur rent collec tor, gas channel, diffusion la yer, and c atalyst la yer for b oth ano de and c athode and a membr ane). Additionally , ther e ma y be coolan t channels , and it ma y be tha t for mesh c onstr uction reasons each of these ph ysical zones is made up of mor e than one mesh z one . Even f or small stacks , you c an easily end up ha ving hundr eds of c ell z ones in an ANSY S Fluen t mesh. Therefore, you ma y want to consider numb ering the fuel c ells in a stack and t o use the assigned fuel c ell numb er in the names of the mesh z ones .When y ou set up y our stack ed fuel c ell c ase, you w ould use the Match Z one N ame P attern field t o pick all the z ones b elonging t o a single fuel c ell in the stack, rather than scr olling thr ough the p otentially v ery long list and selec ting them manually . 33.1.6.7. Reporting on the S olution ( ReportsTab) You c an use the Rep orts tab of the PEM F uel C ell M odel dialo g box to set up par amet ers tha t will be useful in r eporting da ta relevant to the fuel c ell. Figur e 33.14: The Rep orts Tab of the PEM F uel C ell M odel D ialo g Box 2435Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the PEMFC M odelThe Electrolyt e Projec ted A rea field r equir es the pr ojec ted ar ea of the M embr ane E lectrolyt e Assembly (MEA) and is only used t o calcula te the a verage cur rent densit y.The assembly c onsists of the membr ane and the c atalyst la yers ab ove and b elow the membr ane. The External C ontact In terface(s) fields r equir e the fac e zones tha t act as e xternal elec trical contact surfaces for the ano de and the c athode. These inputs ar e used t o report cell v oltage . For p otentiosta tic b oundar y conditions , this is the diff er- ence between the pr ovided v alues , but f or galv anosta tic b oundar y conditions , the c ell v oltage is par t of the solution. 33.1.7. PEMFC M odel B oundar y Conditions The f ollowing b oundar y conditions need t o be defined f or the PEMFC simula tion based on y our problem sp ecific ation: •Anode Inlet –Mass flo w rate –Temp erature –Direction sp ecific ation metho d –Mass fr actions (f or e xample ,h2, and h2o ) –The c oolan t must be set t o zero if c oolan t channels ar e enabled –UDS-4 ( Water Saturation in C hannels) must b e set t o zero •Cathode Inlet –Mass flo w rate –Temp erature –Direction sp ecific ation metho d –Mass fr actions (f or e xample o2,h2o , and n2) –The c oolan t must be set t o zero if c oolan t channels ar e enabled –UDS-4 ( Water Saturation in C hannels) must b e set t o zero •Coolan t Inlet (if an y) –Mass flo w rate –Temp erature –Direction sp ecific ation metho d –Coolan t mass fr action set t o 1 –UDS-4 ( Water Saturation in C hannels) must b e set t o zero Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2436Modeling F uel C ells•Pressur e Outlets (all) Realistic backflo w conditions . •Terminal A node –Temp erature (or hea t flux if k nown) –UDS-0 (elec tric potential) set t o gr ound v oltage •Terminal C athode –Temp erature (or hea t flux if k nown) –UDS-0 (elec tric potential) is set t o the v oltage of the c athode (if solving t o constan t voltage), or the UDS- 0 (elec tric potential) flux is set t o the cur rent densit y in (SI units) (if solving f or constan t cur rent). Note tha t the sign of the UDS-0 flux on the c athode side is nega tive. 33.1.8. Solution G uidelines f or the PEMFC M odel For p otentiosta tic b oundar y conditions , after initializa tion, solutions ar e calcula ted easily f or c ell v oltages close t o the op en-cir cuit v oltage .The same c an b e said f or galv anosta tic b oundar y conditions and lo w elec tric cur rent. By lowering the c ell v oltage or b y raising the a verage elec tric cur rent, you c an c alcula te subsequen t sta tionar y solutions . In the e vent of c onvergenc e pr oblems , it is r ecommended tha t you change the multigr id cycle t o F- cycle with BCGST AB (bi-c onjuga te gr adien t stabiliz ed metho d) selec ted as the stabiliza tion metho d for the sp ecies and the t wo potential equa tions . For the sp ecies and the user-defined sc alar equa tions , it ma y be nec essar y to reduc e the t ermina tion (cr iteria) of the multigr id-c ycles t o . For stack simula tions , the t ermina tion cr iterion ma y be reduc ed t o for the t wo potential equa tions . Also, it ma y be useful t o tur n off Joule H eating and Reac tion H eating in the PEM F uel C ell M odel dialo g box (in the Model tab) f or the first f ew (appr oxima tely 5-10) it erations af ter initializa tion. This allows the t wo elec tric potentials t o adjust fr om their initial v alues t o mor e ph ysical values , avoiding the p ossibilit y of e xtreme elec trochemic al reactions and elec tric cur rents tha t would in tur n ad versely impac t the solution. 33.1.9. Postpr ocessing the PEMFC M odel You c an p erform p ostpr ocessing using standar d ANSY S Fluen t quan tities and b y using user-defined scalars and user-defined memor y allo cations . By default , the ANSY S Fluen t PEMFC mo del defines se v- eral user-defined sc alars and user-defined memor y allo cations , descr ibed in Table 33.1: User-D efined Scalar A llocations (p.2437 ) and Table 33.2: User-D efined M emor y Allocations (p.2438 ). Table 33.1: User-D efined Sc alar A llocations Electric Potential (solid phase p otential) ( Volts) UDS 0 Protonic P otential (membr ane phase p otential) ( Volts) UDS 1 Capillar y Pressur e UDS 2 Water C ontent UDS 3 2437Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the PEMFC M odelLiquid S aturation in C hannels UDS 4 Table 33.2: User-D efined M emor y Allocations X Current Flux D ensit y (A/m2) UDM 0 Y Current Flux D ensit y (A/m2) UDM 1 Z Current Flux D ensit y (A/m2) UDM 2 Current Flux D ensit y Magnitude (A/m2) UDM 3 Ohmic H eat Source (W/m3) UDM 4 Reaction H eat Source (W/m3) UDM 5 Overpotential ( Volts) UDM 6 Evaporation t o Vapor P hase C hange S ource (kg/m3-s) UDM 7 Osmotic D rag C oefficien t UDM 8 Water A ctivit y UDM 9 Equilibr ium Water C ontent UDM 10 Absor ption fr om Vapor phase change sour ce (kg/m3-s) UDM 11 Absor ption fr om Liquid P hase C hange S ource (kg/m3-s) UDM 12 Transf er C urrent (A/m3) UDM 13 Liquid S aturation in P orous M edia UDM 14 GDL Liquid R emo val (k g/m3-s) UDM 15 Osmotic D rag S ource (kg/m3-s) UDM 16 Capillar y Pressur e (P a) UDM 17 Pressur e Gradien t Source (kg/m3-s) UDM 18 You c an obtain this list b y op ening the Execut e On D emand dialo g box and pulling do wn the Func tion drop-do wn list. User D efined → User D efined → Execut e on D emand ... and acc ess the e xecut e-on-demand func tion c alled list_pemfc_udf . Alternatively, you c an view the listing tha t app ears when y ou first load y our PEMFC c ase, or y ou c an type list_pemfc_udf in the t ext user in terface and the listing will app ear in the c onsole windo w. Note •For field v ariables tha t are stored in UDM, use the c orresponding v ariables f or p ostpr o- cessing . Postpr ocessing the UDM itself is not r ecommended . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2438Modeling F uel C ells•For reviewing simula tion r esults in CFD-P ost f or cases in volving UDM or UDS, export the solution da ta as CFD-P ost-c ompa tible file (.cdat ) in F luen t and then load this file in to CFD-P ost. Imp ortant When y ou load older PEM F uel C ell c ases in to ANSY S Fluen t, and y ou ar e monit oring a UDS using v olume or sur face monit ors, mak e sur e you r e-visit the c orresponding monit ors dialo g box (for e xample , the Volume M onit or or the Surface M onit or dialo g box) to verify tha t the c orrect UDS name is used f or the appr opriate monit or. 33.1.10. User-A ccessible F unc tions As not ed in Properties, you c an dir ectly inc orporate your o wn f ormula tions and da ta for the pr operties of the fuel c ell membr ane using the pemfc_user.c sour ce code file . The f ollowing listing r epresen ts a descr iption of the c ontents of the pemfc_user.c sour ce code file: real Get_P_sat(real T, cell_t c, Thread *t) Retur ns the v alue of the w ater vapor sa turation pr essur e as a func tion of t emp erature (Equa tion 25.47 ) or other user-sp ecified v alues . real Water_Activity(real P, real T, cell_t c, Thread *t) Retur ns the v alue of w ater ac tivit y (Equa tion 25.26 ). real Osmotic_Drag_Coefficient(cell_t c, Thread *t) Retur ns the v alue of the osmotic dr ag c oefficien t (Equa tion 25.46 ). real Membrane_Conductivity(real lam, cell_t c, Thread *t) Retur ns the v alue of the pr otonic c onduc tivit y in MEA ( Equa tion 25.41 ). real Water_Content_Diffusivity(real lam, real T, real mem_mol_dens- ity,cell_tc,Thread*t) Retur ns the v alue of the w ater content diffusivit y in the MEA ( Equa tion 25.43 ). real Gas_Diffusivity(cell_t c, Thread *t, int j_spe) Retur ns the v alue of the gaseous sp ecies diffusivities in the channels , gas diffusion la yers, micr o porous layers, and c atalysts ( Equa tion 25.38 ). real MCD_Gas_Diffusivity(cell_t c, Thread *t, int i) Retur ns the t ortuosit y-corrected v alue of the gas sp ecies diffusion c oefficien ts comput ed with the mul- ticomp onen t diffusion option ( Equa tion 25.38 ). real Compute_Js(real s, Thread *t) Comput es the L everett func tion; namely , the - relation ( Equa tion 25.33 ). Real Capillary_P_Diffusivity(real sat, real K_abs, cell_t c, Thread *t) Retur ns the in Equa tion 25.27 . 2439Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the PEMFC M odelreal Water_Content(cell_t c, Thread *t) Comput es the w ater content . real Anode_AV_Ratio(cell_t c, Thread *t) Retur ns the v alue of the sp ecific ac tive sur face area ( in Equa tion 25.5 ) for the ano de c atalyst. real Cathode_AV_Ratio(cell_t c, Thread *t) Retur ns the v alue of the sp ecific ac tive sur face area ( in Equa tion 25.6 ) for the c athode c atalyst. real Anode_J_TransCoef(cell_t c, Thread *t) Retur ns the v alue of the ano de r eaction r eference cur rent densit y used in Equa tion 25.5 . real Cathode_J_TransCoef(cell_t c, Thread *t) Retur ns the v alue of the c athode r eaction r eference cur rent densit y used in Equa tion 25.6 . real Open_Cell_Voltage(cell_t c, Thread *t) Retur ns the v alue of the half-c ell p otential used in Equa tion 25.11 and Equa tion 25.12 . real Leakage_Current(cell_t c, Thread *t) Retur ns the v alue of the t otal leak age cur rent ( in Equa tion 25.48 through Equa tion 25.50 ). real resistance_in_channel (real sat) Retur ns momen tum r esistanc e as a func tion of liquid sa turation in gas channels . void Set_UDS_Names(char uds[n_uds_required][STRING_SIZE]) Used t o rename user-defined sc alars (UDSs). Note tha t the units of the user defined sc alars c annot b e changed . void Set_UDS_Names(char uds[n_uds_required][STRING_SIZE]) { strncpy(uds[0], "Electric Potential", STRING_SIZE-1); strncpy(uds[1], "Protonic Potential", STRING_SIZE-1); strncpy(uds[2], "Cap. Pressure", STRING_SIZE-1); strncpy(uds[3], "Water Content", STRING_SIZE-1); strncpy(uds[4], "Liq. Saturation in Channels", STRING_SIZE-1); } If you w ant to change the names of UDSs , change the sec ond ar gumen t of the strncpy func tions , recompile and link the mo dule as with an y mo dific ation t o pemfc_user.c . Note tha t STRING_SIZE is fix ed in pemfc.h and should not b e changed . Imp ortant When y ou load older PEM F uel C ell c ases in to ANSY S Fluen t, and y ou ar e monit oring a UDS using v olume or sur face monit ors, mak e sur e you r e-visit the c orresponding mon- itors dialo g box (for e xample , the Volume M onit or or the Surface M onit or dialo g box) to mak e sur e tha t the c orrect UDS name is used f or the appr opriate monit or. void Set_UDM_Names(char udm[n_udm_required][STRING_SIZE]) Used t o rename user defined memor y (UDMs). Note tha t the units of user defined memor y cannot b e changed . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2440Modeling F uel C ellsvoid Set_UDM_Names(char udm[n_udm_required][STRING_SIZE]) { strncpy(udm[0], "X Current Flux Density", STRING_SIZE-1); strncpy(udm[1], "Y Current Flux Density", STRING_SIZE-1); strncpy(udm[2], "Z Current Flux Density", STRING_SIZE-1); strncpy(udm[3], "Current Flux Density Magnitude", STRING_SIZE-1); strncpy(udm[4], "Ohmic Heat Source", STRING_SIZE-1); strncpy(udm[5], "Reaction Heat Source", STRING_SIZE-1); strncpy(udm[6], "Overpotential", STRING_SIZE-1); strncpy(udm[7], "Evaporation to Vapor", STRING_SIZE-1); strncpy(udm[8], "Osmotic Drag Coefficient", STRING_SIZE-1); strncpy(udm[9], "Water Activity", STRING_SIZE-1); strncpy(udm[10], "Equilibrium Water Content", STRING_SIZE-1); strncpy(udm[11], "Absorption from Vapor", STRING_SIZE-1); strncpy(udm[12], "Absorption from Liquid", STRING_SIZE-1); strncpy(udm[13], "Transfer Current", STRING_SIZE-1); strncpy(udm[14], "Liquid Saturation", STRING_SIZE-1); strncpy(udm[15], "GDL Liquid Removal", STRING_SIZE-1); strncpy(udm[16], "Osmotic Drag Source (PEM)", STRING_SIZE-1); strncpy(udm[17], "Cap. Pressure", STRING_SIZE-1); strncpy(udm[18], "Pressure Gradient Source", STRING_SIZE-1); } If you w ant to change the names of UDMs , change the sec ond ar gumen t of the strncpy func tions , recompile and link the mo dule as with an y mo dific ation t o pemfc_user.c . Note tha t STRING_SIZE is fix ed in pemfc.h and should not b e changed . Imp ortant When y ou load older PEM F uel C ell c ases in to ANSY S Fluen t, and y ou ar e monit oring a UDM using v olume or sur face monit ors, mak e sur e you r e-visit the c orresponding monit ors dialo g box (for e xample , the Volume M onit or or the Surface M onit or dialo g box) to mak e sur e tha t the c orrect UDM name is used f or the appr opriate monit or. real electric_contact_resistance(face_t f, Thread *t, int ns) Retur ns the v alue f or the elec trical contact resistanc e. real Transfer_Current(real i_ref, real gamma, int species_i, real alpha_a, real alpha_c, real *dRade, real *dRcde, Thread *t, cell_t c, real cath- ode_volume) Comput es the tr ansf er cur rent ( ), corresponding t o in Equa tion 25.5 and in Equa tion 25.6 . Inputs f or this func tion include: effective transf er cur rent coefficien t, comput ed b y Cath- ode_J_TransCoef(c,t) or Anode_J_TransCoef(c,t)i_ref cathode or ano de c oncentration e xponen t gamma species inde x used in fuel c ells (f or e xample i_o2 , i_h2,i_h2o ) species_i produc t of ano de e xchange c oefficien t and alpha_a produc t of c athode e xchange c oefficien t and alpha_c current thr ead t current cell c total v olume of c athode c atalyst la yer cathode_volume 2441Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the PEMFC M odelOutputs f or this func tion include: ano de or c athode v olumetr ic tr ansf er cur rent ( in Equa tion 25.5 or in Equa tion 25.6 )source partial der ivative of with r espect to ac tivation loss *dRade partial der ivative of with r espect to ac tivation loss *dRcde Thermal_ctk_pemfc(face_t f, Thread *t) Used t o change the c onstan t value of Thermal C ontact Resistanc e set in the Porous Jump dialo g box to a lo cally v ariable v alue . Phase_Change_const(cell_t c, Thread *t) Used t o change the c onstan t value of used t o comput e the gas-liquid phase change r ate. For mor e inf ormation, see the f ollowing sec tions: 33.1.10.1. Compiling the C ustomiz ed PEMFC S ource Code 33.1.10.1. Compiling the C ustomiz ed P EMFC S our ce Code This sec tion includes instr uctions on ho w to compile a cust omiz ed PEM F uel C ell user-defined mo dule . Imp ortant It is assumed tha t you ha ve a basic familiar ity with c ompiling user-defined func tions (UDFs). For an in troduc tion on ho w to compile UDFs , refer to the Fluen t Customiza tion M anual . You will first w ant to use a lo cal copy of the pemfc directory in the addons directory before you recompile the PEM F uel C ell mo dule . 33.1.10.1.1. Compiling the C ustomiz ed S our ce Code Under Linux 1.Make a lo cal copy of the pemfc directory. Do not cr eate a symb olic link. a.Create a dir ectory for the cust om pemfc libr aries (f or e xample ,/home/custom-build ). Imp ortant The cust om v ersion of the libr ary must b e named acc ording t o the c onvention used b y ANSY S Fluen t: for e xample ,pemfc . b.Copy the pemfc libr ary from the installa tion of ANSY S Fluen t (Ansys Inc\v195\fluent\flu- ent19.5.0\addons ) to your newly cr eated dir ectory. 2.Change dir ectories t o the pemfc/src directory. 3.Make changes t o the pemfc_user.c file. 4.Define the FLUENT_ADDONS environmen t variable t o correspond t o your cust omiz ed v ersion of the PEM F uel C ell mo dule . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2442Modeling F uel C ells5.Change dir ectories t o the pemfc/ directory. 6.Issue the f ollowing make command: make FLUENT_INC=[ansys_inc/v195/fluent/fluent19.5.0] FLUENT_ARCH=[arch] -f Makefile-client wher e arch is lnx86 on LINUX, or ultra on the Sun op erating sy stem, and so on. The f ollowing e xample demonstr ates the st eps r equir ed t o set up and r un a cust omiz ed v ersion of the PEM F uel C ell mo dule tha t is lo cated in a f older c alled home/sample . 1.Make a dir ectory (for e xample ,mkdir -p /home/sample ). 2.Copy the default addon libr ary to this lo cation. cp -RH [ansys_inc/v195/fluent]/fluent19.5.0/addons/pemfc /home/sample/pemfc 3.Using a t ext edit or, mak e the appr opriate changes t o the pemfc_user.c file lo cated in /home/sample/pemfc/src/pemfc_user.c 4.Build the libr ary. cd /home/sample/pemfc make FLUENT_INC=[ansys_inc/v195/fluent/fluent19.5.0] FLUENT_ARCH=[arch] -f Makefile-client 5.Set the FLUENT_ADDONS environmen t variable (using CSH, other shells will diff er). setenv FLUENT_ADDONS /home/sample 6.Start ANSY S Fluen t and load the cust omiz ed mo dule using the t ext interface command . 33.1.10.1.2. Compiling the C ustomiz ed S our ce Code under Windo ws 1.Make a lo cal copy of the pemfc folder . Do not cr eate a shor tcut. a.Create a dir ectory for the cust om pemfc libr aries (f or e xample ,/home/custom-build ). b.Copy the pemfc libr ary from the installa tion of ANSY S Fluen t (Ansys Inc\v195\fluent\flu- ent19.5.0\addons ) to your newly cr eated dir ectory. 2.Make sur e tha t the $FLUENT_INC environmen t variable is c orrectly set t o the cur rent ANSY S Fluen t installa tion dir ectory (for e xample ,ANSYS Inc\v195\fluent ). 3.Open Visual S tudio .NET at the DOS pr ompt. 4.Enter the pemfc\src folder . 5.Modify the pemfc_user.c file as desir ed and sa ve the changes . 6.Change y our w orking dir ectory to pemfc (for e xample ,/home/custom-build/pemfc ) and build the cust om addon libr ary: nmake /f makefile_master-client.nt 2443Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the PEMFC M odel7.Define the FLUENT_ADDONS environmen t variable t o correspond t o your cust omiz ed v ersion of the PEM F uel C ell mo dule in one of f ollowing w ays: •Set the pa th to FLUENT_ADDONS globally . •In the Environmen t tab of F luen t Launcher , enter inf ormation f or FLUENT_ADDONS in the Other Environmen t Variables field , for e xample: FLUENT_ADDONS= :\home\custom-build wher e is the tar get dr ive lett er including the c olon (f or e xample ,D:). 33.2. Using the F uel C ell and E lectrolysis M odel The pr ocedur e for setting up and solving fuel c ell pr oblems using the F uel C ell and E lectrolysis M odel is descr ibed in detail in this chapt er. Refer to the f ollowing sec tions f or mor e inf ormation: 33.2.1. Overview and Limita tions 33.2.2. Geometr y Definition f or the F uel C ell and E lectrolysis M odel 33.2.3. Installing the F uel C ell and E lectrolysis M odel 33.2.4. Loading the F uel C ell and E lectrolysis M odule 33.2.5. Workflow for U sing the F uel C ell and E lectrolysis M odule 33.2.6. Setting U p the F uel C ell and E lectrolysis M odule 33.2.7. Modeling C urrent Collec tors 33.2.8. Fuel C ell and E lectrolysis M odel B oundar y Conditions 33.2.9. Solution G uidelines f or the F uel C ell and E lectrolysis M odel 33.2.10. Postpr ocessing the F uel C ell and E lectrolysis M odel 33.2.11. User-A ccessible F unctions 33.2.1. Overview and Limita tions The ANSY S Fluen t Fuel C ell and E lectrolysis M odel ar e made up of se veral user-defined func tions (UDFs) and a gr aphic al user in terface.The p otential fields ar e solv ed as user-defined sc alars .The liquid water sa turation, , and the w ater content, , are also solv ed as user-defined sc alars .The elec trochem- ical reactions o ccur ring on the c atalyst ar e mo deled thr ough v arious sour ce terms while other mo del paramet ers ar e handled thr ough the user in terface.The F uel C ell and E lectrolysis M odel c an b e used in par allel ANSY S Fluen t as w ell. Note the f ollowing limita tion when using the F uel C ell and E lectrolysis mo del: •The anisotr opic sp ecies diffusivit y option is not c ompa tible with the F uel C ell and E lectrolysis mo del. 33.2.2. Geometr y Definition f or the F uel C ell and E lectrolysis M odel Due t o the fac t tha t ther e ar e a numb er of diff erent ph ysical zones asso ciated with the fuel c ell, the following r egions must b e pr esen t in the fuel c ell mesh: •Anode flo w channel •Anode gas diffusion la yer •Anode c atalyst la yer Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2444Modeling F uel C ells•Membr ane la yer •Cathode c atalyst la yer •Cathode gas diffusion la yer •Cathode flo w channel The f ollowing z ones ha ve to be iden tified , if pr esen t in the fuel c ell mesh: •Anode cur rent collec tor •Cathode cur rent collec tor •Coolan t channel 33.2.3. Installing the F uel C ell and E lectrolysis M odel The F uel C ell and E lectrolysis M odel is pr ovided as an add-on mo dule with the standar d ANSY S Fluen t licensed sof tware.The mo dule is installed with the standar d installa tion of ANSY S Fluen t in a dir ectory called addons/fuelcells in y our installa tion ar ea.The F uel C ell and E lectrolysis M odel c onsists of a UDF libr ary and a pr e-compiled Scheme libr ary, which must b e loaded and ac tivated b efore calcula tions can b e performed . 33.2.4. Loading the F uel C ell and E lectrolysis M odule The F uel C ell and E lectrolysis mo dule is loaded in to ANSY S Fluen t thr ough the t ext user in terface (TUI). The mo dule c an only b e loaded af ter a v alid ANSY S Fluen t case file has b een set or r ead.The t ext command t o load the add-on mo dule is define → models → addon-module A list of ANSY S Fluen t add-on mo dules is displa yed: > /define/models/addon-module Fluent Addon Modules: 0. None 1. MHD Model 2. Fiber Model 3. Fuel Cell and Electrolysis Model 4. SOFC Model with Unresolved Electrolyte 5. Population Balance Model 6. Adjoint Solver 7. Battery Module 8. MSMD Battery Model 9. PEM Fuel Cell Model Enter Module Number: [0] 3 Selec t the F uel C ell and E lectrolysis M odel b y en tering the mo dule numb er 3. During the loading process, a Scheme libr ary (containing the gr aphic al and t ext user in terface) and a UDF libr ary (containing a set of user defined func tions) ar e loaded in to ANSY S Fluen t. 33.2.5. Workflo w for U sing the F uel C ell and E lectrolysis M odule The F uel C ell and E lectrolysis M odel c an b e used t o mo del p olymer elec trolyt e membr ane fuel c ells (PEMFC), solid o xide fuel c ells (SOFC), and the pr ocess of high-t emp erature elec trolysis.The f ollowing 2445Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the F uel C ell and E lectrolysis M odeldescr ibes an o verview of the pr ocedur e requir ed in or der t o use the F uel C ell and E lectrolysis M odel in ANSY S Fluen t. 1.Start ANSY S Fluen t. 2.Read the c ase file . 3.Scale the gr id, if nec essar y. 4.Use the Fuel C ell and E lectrolysis M odels dialo g box to define the fuel c ell mo del par amet ers. 5.Define ma terial pr operties. 6.Set the op erating c onditions . 7.Set the b oundar y conditions . 8.Start the c alcula tions . 9.Save the c ase and da ta files . 10.Process y our r esults . Imp ortant The Fuel C ell and E lectrolysis M odels dialo g box gr eatly simplifies the input of par amet ers and b oundar y conditions , but it do es not r eplac e the b oundar y conditions in terface. Therefore, it is a go od policy to star t the setup with the Fuel C ell and E lectrolysis M odels dialo g box and do the finishing st eps f or b oundar y conditions af terwards. Imp ortant Note tha t the major ity of this chapt er descr ibes ho w to set up the ANSY S Fluen t Fuel C ell and E lectrolysis M odel using the gr aphic al user in terface.You c an also p erform v arious tasks using the t ext user in terface. For mor e inf ormation, see Using the F uel C ell and E lectrolysis Text User In terface. 33.2.6. Setting U p the F uel C ell and E lectrolysis M odule Onc e the mo dule has b een loaded , in or der t o set fuel c ell mo del par amet ers and assign pr operties to the r elevant regions in y our fuel c ell, you need t o acc ess the fuel c ell gr aphic al user in terface (the Fuel C ell and E lectrolysis M odels dialo g box). To op en the Fuel C ell and E lectrolysis M odels dialo g box: In the tr ee under the Models branch, right- click Fuel C ells and E lectrolysis and selec t Edit... in the menu tha t op ens. Setup → Models → Fuel C ells and E lectrolysis Edit... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2446Modeling F uel C ellsFigur e 33.15: The F uel C ell and E lectrolysis Option in the Tree By default , the PEMFC mo del is alr eady enabled , however, you c an also cho ose the SOFC or the E lec- trolysis mo dels . Using the Fuel C ell and E lectrolysis M odels dialo g box, you c an iden tify the r elevant zones f or the current collec tors, flow channels , gas diffusion la yers, catalyst la yers, and the membr ane/elec trolyt e. You c an sp ecify the f ollowing inputs using the Fuel C ell and E lectrolysis M odels dialo g box. Optional inputs ar e indic ated as such. 1.Enable the appr opriate type of fuel c ell mo del, either PEMFC ,SOFC , or Electrolysis. 2.Enable either the single-phase or the multi-phase fuel c ell mo del (if PEMFC is selec ted). 3.Set the appr opriate options f or the fuel c ell mo del (optional). 4.Set the v arious par amet ers f or the fuel c ell mo del. 5.Selec t the appr opriate zones and sp ecify the pr operties on the ano de side . 6.Selec t the appr opriate zones and sp ecify the pr operties of the membr ane/elec trolyt e. 7.Selec t the appr opriate zones and sp ecify the pr operties on the c athode side . 8.Provide input f or ad vanced f eatures such as c ontact resistivities , coolan t channel pr operties, or stack managemen t settings (optional). 9.Set solution c ontrols such as under-r elaxa tion fac tors (optional). 2447Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the F uel C ell and E lectrolysis M odel10.Provide input t o assist r eporting (optional). Refer to the f ollowing sec tions f or mor e inf ormation: 33.2.6.1. Specifying M odel Options (M odel Tab) 33.2.6.2. Specifying M odel P aramet ers (P aramet ers Tab) 33.2.6.3. Specifying A node P roperties (A node Tab) 33.2.6.4. Specifying E lectrolyte/M embr ane P roperties (E lectrolyte Tab) 33.2.6.5. Specifying C athode P roperties (C athode Tab) 33.2.6.6. Setting A dvanced P roperties (A dvanced Tab) 33.2.6.7. Reporting on the S olution (R eports Tab) 33.2.6.1. Specifying Mo del O ptions ( Mo del Tab) The Model tab of the Fuel C ell and E lectrolysis M odels dialo g box allo ws you t o tur n on or off various options when solving a fuel c ell pr oblem. To mo del p olymer elec trolyt e membr ane fuel c ells, enable the PEMFC option in the Model tab . Likewise , to mo del solid o xide fuel c ells, enable the SOFC option in the Model tab . Finally , to mo del elec trolysis, enable the Electrolysis option in the Model tab. Figur e 33.16: The M odel Options in the F uel C ell and E lectrolysis M odels D ialo g Box—PEMFC Enabled Several fuel c ell mo del options ar e available in the Model tab of the Fuel C ell and E lectrolysis Models dialo g box including: •The Joule H eating option tak es in to acc oun t ohmic hea ting .This option includes the term in the ener gy sour ce term fr om Equa tion 25.75 in the c alcula tions . •The Reac tion H eating option tak es in to acc oun t the hea t gener ated b y the elec trochemic al reactions , which includes the term, and the pr oduc t of tr ansf er cur rent and the o ver-p otentials in the ener gy sour ce term fr om Equa tion 25.75 in the c alcula tions . •The Electrochemistr y Sour ces option allo ws the F uel C ell and E lectrolysis M odel t o tak e elec trochemistr y effects in to acc oun t. If you ar e only in terested in the basic flo w field thr oughout the fuel c ell, you c an tur n off the Electrochemistr y Sour ces option in or der t o suppr ess most eff ects of the F uel C ell and E lectrolysis Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2448Modeling F uel C ellsModel. To tur n off all eff ects of the F uel C ell and E lectrolysis M odel, you should also tur n off the Membr ane Water Transp ort and Multiphase options . •The Butler-V olmer R ate option (the default) is used t o comput e the tr ansf er cur rents inside the c atalyst layers. If this option is tur ned off , the Tafel appr oxima tion ( Equa tion 25.62 ) is used . •The Membr ane Water Transp ort option tak es in to acc oun t the tr ansp ort of w ater acr oss the membr ane. This option is only a vailable f or the PEMFC mo del. •The Multiphase option tak es in to acc oun t multiphase c alcula tions . Use this option if y ou ar e solving f or appr oxima te liquid tr ansp ort in the gas diffusion la yer of the fuel c ell. (PEMFC only) •The Multic omp onen t Diffusion option is used t o comput e the gas sp ecies mass diffusivit y using the full multic omp onen t diffusion metho d as descr ibed in Equa tion 25.82 , as opp osed t o the default option tha t uses Equa tion 25.80 . •The Anisotr opic E-C onduc tivit y in P orous E lectrode option is used t o mo del the t ypic ally non-isotr opic elec trical conduc tivit y. It is applic able only f or p orous elec trodes (gas diffusion la yers). Due t o the fibr ous str ucture of the p orous ma terial tha t is used f or the elec trodes (or gas diffusion layer), the elec trical conduc tivit y is t ypic ally non-isotr opic al, with the cr oss-plane c omp onen ts b eing orders of magnitude smaller than the in-plane c omp onen ts.This c an b e mo deled using the Aniso- tropic E-C onduc tivit y in P orous E lectrode setting .When this option is enabled , the Electrical Conduc tivit y for the solid ma terial used in the elec trolyt e is no longer used . Inst ead, you need t o specify , for this solid ma terial, the elec trical conduc tivit y by cho osing one of the thr ee non-isotr op- ical options f or the UDS diffusivit y (UDS-0 ).The thr ee options ar e:anisotr opic ;orthotr opic ; and cyl-or thotr opic . For mor e inf ormation ab out these UDS D iffusivit y options , refer to the ANSY S Fluen t User's G uide (p.1). For e xample , to use this f eature, perform the f ollowing st eps: –Selec t the Anisotr opic E-C onduc tivit y in P orous E lectrode option in the Model tab of the Fuel C ell and E lectrolysis M odels dialo g box. –In the Create/Edit M aterials dialo g box, selec t defined-per-uds for UDS D iffusivit y for the solid material tha t is t o be used f or the p orous elec trode. –Selec t one of the thr ee options f or UDS-0: anisotr opic ;orthotr opic ; or cyl-or thotr opic and set the appr opriate values . Imp ortant Note tha t, in this c ase, the Electrical C onduc tivit y for this solid ma terial is ignor ed. •For PEMFC pr oblems , you c an use the Under-Relaxa tion F actors fields t o influenc e the solution pr ocess. The sa turation sour ce term in Equa tion 25.77 usually r equir es under-r elaxa tion. You c an change the default v alue f or the under-r elaxa tion fac tor b y changing the v alue f or Saturation S our ce. The w ater content, , in Equa tion 25.88 also ma y need under-r elaxa tion. You c an change the default value f or the under-r elaxa tion fac tor b y changing the v alue f or Water C ontent. Under Automa tic S ettings , the f ollowing par allel multigr id solv er control par amet ers ar e available: 2449Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the F uel C ell and E lectrolysis M odel•Enable S mooth P artition : Enables the smo oth par titioning pr ocess when r unning in P arallel. When this option is enabled , the fuel c ell par allel solv er: –Uses the M etis metho d for par titioning the mesh –Enables Laplac e Smoothing –Partitions and distr ibut es the mesh da ta to all c omput e no des •F-cycle f or A ll Equa tions : Sets the multigr id cycle t ype to F c ycle f or all equa tions tha t are being solv ed. This c ontrol overrides the equa tion c ycle settings in the Advanc ed S olution C ontrols dialo g box. Nearly all options ar e tur ned on b y default. You ma y want to override the default v alues , dep ending on the pr oblem y ou w ant to mo del. For instanc e, if y ou ar e not c oncerned with the hea t gener ated due t o chemic al reaction, then y ou ma y want to tur n off the Reac tion H eating option. 33.2.6.2. Specifying Mo del P aramet ers ( Paramet ers Tab) You c an use the Paramet ers tab of the Fuel C ell and E lectrolysis M odels dialo g box to sp ecify the elec trochemistr y par amet ers f or the F uel C ell and E lectrolysis M odel, reference diffusivities f or the reactants, among other mo del par amet ers. Figur e 33.17: The P aramet ers Tab of the F uel C ell and E lectrolysis M odels D ialo g Box There ar e various par amet ers under Electrochemistr y in the Fuel C ell and E lectrolysis M odels dialo g box. For b oth the ano de and the c athode, you c an also set the f ollowing par amet ers or lea ve the default v alues . •The Ref. Current Densit y corresponds t o and , the r eference exchange cur rent densit y from Equa tion 25.59 and Equa tion 25.60 . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2450Modeling F uel C ells•The Ref. Conc entration corresponds t o the r eference concentration ( and ) with units of 1 (see Equa tion 25.59 and Equa tion 25.60 ). •The Conc entration E xponen t corresponds t o , the c oncentration dep endenc e from Equa tion 25.59 . •The Exchange C oefficien t (a) and Exchange C oefficien t (c) correspond t o the tr ansf er coefficien ts, and , from Equa tion 25.59 and Equa tion 25.60 . •The Open-C ircuit Voltage corresponds t o in Equa tion 25.64 . •The Leak age C urrent corresponds t o in Equa tion 25.92 through Equa tion 25.97 .This is the t otal amoun t of tr ansf er cur rent (A) due t o fuel-o xidan t cross-o ver (leak age thr ough the elec trolyt e).When this happ ens, the fuel c ell gener ates less cur rent esp ecially f or cases with lo w values of fuel or air utiliza tion. In addition t o the c onstan t value y ou c an sp ecify in the Electrochemistr y tab , you c an also sp ecify the leak age cur rent thr ough the user-defined func tion Leakge_Current() . For mor e inf ormation, see User-A ccessible F unctions (p.2468 ). Moreover, the f ollowing par amet ers c an also b e set her e: •The Referenc e Diffusivities correspond t o from Equa tion 25.80 , the sp ecies mass diffusivit y.These are not b e requir ed if the Multic omp onen t Diffusion option is enabled in the Model tab . •The Pore Blo ckage f or G as D iffusion corresponds t o from Equa tion 25.80 for multiphase PEMFC c al- cula tions . •The Pore Blo ckage f or Transf er C urrent is used t o acc oun t for liquid blo ckage t o the r eaction sur face by mo difying and in Equa tion 25.59 through Equa tion 25.62 as f ollows: wher e is the p ore blo ckage f or tr ansf er cur rent. •The Exponen t for r elative permeabilit y corresponds t o in Equa tion 25.78 . Note tha t, conventionally , the nega tive voltage is supplied t o the c athode side in p ower consuming devices such as elec trolyz ers. ANSY S Fluen t adopts the in verse nota tion wher e the nega tive voltage is supplied t o the ano de side whilst c athode r emains p ositiv ely char ged .The main r eason f or this discr epanc y is tha t the same infr astructure is used f or b oth the elec trolysis and fuel c ells mo dels . Usage of the t erms "ano de" and "cathode" in this manual and in the user in terface should b e in terpreted according t o conventions f or p ower-supplying de vices. 33.2.6.3. Specifying A node P roperties ( AnodeTab) You c an use the Anode tab of the Fuel C ell and E lectrolysis M odels dialo g box to sp ecify z ones and pr operties of the cur rent collec tor, the flo w channel, the diffusion la yer, and the c atalyst la yer for the ano de p ortion of the fuel c ell. 2451Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the F uel C ell and E lectrolysis M odel33.2.6.3.1. Specifying C urrent C ollec tor P roperties for the A node Figur e 33.18: The A node Tab of the F uel C ell and E lectrolysis M odels D ialo g Box With C urrent Collec tor S elec ted 1.Selec t the Anode tab of the Fuel C ell and E lectrolysis M odels dialo g box. 2.Selec t Current Collec tor under Anode Z one Type. 3.Selec t a c orresponding z one fr om the Zone(s) list. If you ar e mo deling a fuel c ell stack, then y ou must pick all zones of a par ticular t ype as a gr oup . 4.Selec t a Solid M aterial from the c orresponding dr op-do wn list. Solid ma terials c an b e cust omiz ed using the Create/Edit M aterials dialo g box. Note tha t for the Electrical C onduc tivit y, you c an only cho ose a constan t value in the Create/Edit M aterials dialo g box.The solid elec trical conduc tivit y value is the diffusivit y of the solid phase p otential in the solid z ones . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2452Modeling F uel C ells33.2.6.3.2. Specifying F low C hannel P roperties for the A node Figur e 33.19: The A node Tab of the F uel C ell and E lectrolysis M odels D ialo g Box With F low Channel S elec ted 1.Selec t the Anode tab of the Fuel C ell and E lectrolysis M odels dialo g box. 2.Selec t Flow C hannel under Anode Z one Type. 3.Selec t a c orresponding z one fr om the Zone(s) list. 33.2.6.3.3. Specifying P orous Elec trode P roperties for the A node Figur e 33.20: The A node Tab of the F uel C ell and E lectrolysis M odels D ialo g Box With P orous Electrode S elec ted 2453Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the F uel C ell and E lectrolysis M odel1.Selec t the Anode tab of the Fuel C ell and E lectrolysis M odels dialo g box. 2.Selec t Porous E lectrode under Anode Z one Type. 3.Selec t a c orresponding z one fr om the Zone(s) list. If you ar e mo deling a fuel c ell stack, then y ou must pick all zones of a par ticular t ype as a gr oup . 4.Selec t a Solid M aterial from the c orresponding dr op-do wn list. Solid ma terials c an b e cust omiz ed using the Create/Edit M aterials dialo g box. Note tha t for the Electrical C onduc tivit y, you c an only cho ose a constan t value in the Create/Edit M aterials dialo g box.The solid elec trical conduc tivit y value is the diffusivit y of the solid phase p otential in the solid z ones . 5.Specify a v alue f or the Porosit y. 6.Specify a v alue f or the Visc ous Resistanc e. 7.Specify a v alue f or the Contact Angle for multiphase fuel c ell c alcula tions ( in Equa tion 25.79 ). 33.2.6.3.4. Specifying C atal yst L ayer P roperties for the A node Figur e 33.21: The A node Tab of the F uel C ell and E lectrolysis M odels D ialo g Box With TPB Layer (C ataly st) S elec ted 1.Selec t the Anode tab of the Fuel C ell and E lectrolysis M odels dialo g box. 2.Selec t TPB L ayer (C ataly st) under Anode Z one Type. 3.Selec t a c orresponding z one fr om the Zone(s) list. If you ar e mo deling a fuel c ell stack, then y ou must pick all zones of a par ticular t ype as a gr oup . 4.Selec t a Solid M aterial from the c orresponding dr op-do wn list. Solid ma terials c an b e cust omiz ed using the Create/Edit M aterials dialo g box. Note tha t for the Electrical C onduc tivit y, you c an only cho ose a constan t value in the Create/Edit M aterials dialo g box.The solid elec trical conduc tivit y value is the diffusivit y of the solid phase p otential in the solid z ones . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2454Modeling F uel C ells5.Specify a v alue f or the Porosit y. 6.Specify a v alue f or the Visc ous Resistanc e. 7.Specify a v alue f or the Surface/Volume R atio (the sp ecific ac tive sur face area in Equa tion 25.59 ). 8.Specify a v alue f or the Contact Angle for multiphase fuel c ell c alcula tions ( in Equa tion 25.79 ). 33.2.6.3.5. Specifying C ell Z one C onditions for the A node For each c ase of the ano de’s cur rent collec tor, diffusion la yer, and c atalyst la yer, you assign a solid material and/or set the p orosity and the visc ous r esistanc e.These settings r epresen t setting a c ell zone c ondition. With the Update Cell Z ones option tur ned on (the default setting), this c ell z one condition is applied t o all selec ted z ones in the Zone(s) list. If you w ant to set the c ell z one c onditions for each z one individually (using the Cell Z one C onditions task page), you should tur n off the Update Cell Z ones option. 33.2.6.4. Specifying Elec trolyte/Membr ane P roperties ( Elec trolyteTab) You c an use the Electrolyt e tab of the Fuel C ell and E lectrolysis M odels dialo g box to sp ecify z ones and pr operties of the elec trolyt e/membr ane p ortion of the fuel c ell. Figur e 33.22: The E lectrolyt e Tab of the F uel C ell and E lectrolysis M odels D ialo g Box 1.Selec t a c orresponding z one fr om the Zone(s) list. If you ar e mo deling a fuel c ell stack, then y ou must pick all membr ane z ones as a gr oup . 2.Selec t a Solid M aterial from the c orresponding dr op-do wn list. Solid ma terials c an b e cust omiz ed using the Create/Edit M aterials dialo g box. 3.Specify a v alue f or the Equiv alen t Weigh t ( in Equa tion 25.86 ). 4.Specify a v alue f or the Protonic C onduc tion C oefficien t ( in Equa tion 25.84 ).This is used t o calcula te the membr ane phase elec tric conduc tivit y. 2455Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the F uel C ell and E lectrolysis M odel5.Specify a v alue f or the Protonic C onduc tion E xponen t ( in Equa tion 25.84 ). Note tha t the F uel C ell and E lectrolysis M odel allo ws you t o mo del the elec trolyt e/membr ane as either a fluid z one or as a solid z one . For PEMFC, the F uel C ell and E lectrolysis M odel still allo ws for w ater and the ionic cur rent to pass thr ough the elec trolyt e/membr ane. 33.2.6.4.1. Specifying C ell Z one C onditions for the Membr ane When y ou assign a solid ma terial t o the membr ane, you ar e setting a c ell z one c ondition. With the Update Cell Z ones option tur ned on (the default setting), this c ell z one c ondition is applied t o all selec ted z ones in the Zone(s) list. If you w ant to set the c ell z one c onditions f or each z one individually (using the Cell Z one C onditions task page), you should tur n off the Update Cell Z ones option. 33.2.6.5. Specifying C atho de P roperties ( Catho deTab) You c an use the Catho de tab of the Fuel C ell and E lectrolysis M odels dialo g box to sp ecify z ones and pr operties of the cur rent collec tor, the flo w channel, the diffusion la yer, and the c atalyst la yer for the c athode p ortion of the fuel c ell. 33.2.6.5.1. Specifying C urrent C ollec tor P roperties for the C atho de Figur e 33.23: The C atho de Tab of the F uel C ell and E lectrolysis M odels D ialo g Box With C urrent Collec tor S elec ted 1.Selec t the Catho de tab of the Fuel C ell and E lectrolysis M odels dialo g box. 2.Selec t Current Collec tor under Catho de Z one Type. 3.Selec t a c orresponding z one fr om the Zone(s) list. If you ar e mo deling a fuel c ell stack, then y ou must pick all zones of a par ticular t ype as a gr oup . 4.Selec t a Solid M aterial from the c orresponding dr op-do wn list. Solid ma terials c an b e cust omiz ed using the Create/Edit M aterials dialo g box. Note tha t for the Electrical C onduc tivit y, you c an only cho ose Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2456Modeling F uel C ellsa constan t value in the Create/Edit M aterials dialo g box.The solid elec trical conduc tivit y value is the diffusivit y of the solid phase p otential in the solid z ones . 33.2.6.5.2. Specifying F low C hannel P roperties for the C atho de Figur e 33.24: The C atho de Tab of the F uel C ell and E lectrolysis M odels D ialo g Box With F low Channel S elec ted 1.Selec t the Catho de tab of the Fuel C ell and E lectrolysis M odels dialo g box. 2.Selec t Flow C hannel under Catho de Z one Type. 3.Selec t a c orresponding z one fr om the Zone(s) list. If you ar e mo deling a fuel c ell stack, then y ou must pick all zones of a par ticular t ype as a gr oup . 2457Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the F uel C ell and E lectrolysis M odel33.2.6.5.3. Specifying P orous Elec trode P roperties for the C atho de Figur e 33.25: The C atho de Tab of the F uel C ell and E lectrolysis M odels D ialo g Box With P orous Electrode S elec ted 1.Selec t the Catho de tab of the Fuel C ell and E lectrolysis M odels dialo g box. 2.Selec t Porous E lectrode under Catho de Z one Type. 3.Selec t a c orresponding z one fr om the Zone(s) list. If you ar e mo deling a fuel c ell stack, then y ou must pick all zones of a par ticular t ype as a gr oup . 4.Selec t a Solid M aterial from the c orresponding dr op-do wn list. Solid ma terials c an b e cust omiz ed using the Create/Edit M aterials dialo g box. Note tha t for the Electrical C onduc tivit y, you c an only cho ose a constan t value in the Create/Edit M aterials dialo g box.The solid elec trical conduc tivit y value is the diffusivit y of the solid phase p otential in the solid z ones . 5.Specify a v alue f or the Porosit y. 6.Specify a v alue f or the Visc ous Resistanc e. 7.Specify a v alue f or the Contact Angle for multiphase fuel c ell c alcula tions ( in Equa tion 25.79 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2458Modeling F uel C ells33.2.6.5.4. Specifying C atal yst L ayer P roperties for the C atho de Figur e 33.26: The C atho de Tab of the F uel C ell and E lectrolysis M odels D ialo g Box With TPB Layer (C ataly st) S elec ted 1.Selec t the Catho de tab of the Fuel C ell and E lectrolysis M odels dialo g box. 2.Selec t TPB L ayer(C ataly st) under Catho de Z one Type. 3.Selec t a c orresponding z one fr om the Zone(s) list. If you ar e mo deling a fuel c ell stack, then y ou must pick all zones of a par ticular t ype as a gr oup . 4.Selec t a Solid M aterial from the c orresponding dr op-do wn list. Solid ma terials c an b e cust omiz ed using the Create/Edit M aterials dialo g box. Note tha t for the Electrical C onduc tivit y, you c an only cho ose a constan t value in the Create/Edit M aterials dialo g box.The solid elec trical conduc tivit y value is the diffusivit y of the solid phase p otential in the solid z ones . 5.Specify a v alue f or the Porosit y. 6.Specify a v alue f or the Visc ous Resistanc e. 7.Specify a v alue f or the Surface/Volume R atio (the sp ecific ac tive sur face area in Equa tion 25.60 ). 8.Specify a v alue f or the Contact Angle for multiphase fuel c ell c alcula tions ( in Equa tion 25.79 ). 33.2.6.5.5. Specifying C ell Z one C onditions for the C atho de For each c ase of the c athode’s cur rent collec tor, diffusion la yer, and c atalyst la yer, you assign a solid material and/or set the p orosity and the visc ous r esistanc e.These settings r epresen t setting a c ell zone c ondition. With the Update Cell Z ones option tur ned on (the default setting), this c ell z one condition is applied t o all selec ted z ones in the Zone(s) list. If you w ant to set the c ell z one c onditions for each z one individually (using the Cell Z one C onditions task page), you should tur n off the Update Cell Z ones option. 2459Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the F uel C ell and E lectrolysis M odel33.2.6.6. Setting A dvanc ed P roperties ( Advanc edTab) You c an use the Advanc ed tab of the Fuel C ell and E lectrolysis M odels dialo g box to sp ecify the contact resistivit y for an y ma terial in terface in the geometr y, set par amet ers f or c oolan t channels , and define fuel stack units f or managing stacks of fuel c ells. 33.2.6.6.1. Setting C ontac t Resistivities for the F uel C ell and Elec trolysis Mo del Figur e 33.27: The A dvanc ed Tab of the F uel C ell and E lectrolysis M odels D ialo g Box for C ontact Resistivities 1.Selec t the Advanc ed tab of the Fuel C ell and E lectrolysis M odels dialo g box. 2.Selec t Contact Resistivit y under Advanc ed S etup . 3.Selec t an y numb er of c orresponding in terfaces fr om the Available Z one(s) list. These z ones ar e fac e zones o ver which a jump in elec trical potential is c aused b y imp erfect conduc tion. 4.Specify a v alue f or the Resistivit y for each sp ecified z one . Note tha t at porous jump and w all/w all-shado w in terfaces, the c ontact resistivit y is applied a t each fac e.Therefore, you need t o sp ecify the r esistivit y only a t one of the in terface walls, other wise the ac tual r esistanc e will b e doubled a t the in terface. 5.To simplify the input , you c an cho ose t o use the r esistivit y value of the first selec ted z one f or all others as w ell b y tur ning on the Use F irst Value f or A ll option. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2460Modeling F uel C ells33.2.6.6.2. Setting C oolant C hannel P roperties for the F uel C ell and Elec trolysis Mo del Figur e 33.28: The A dvanc ed Tab of the F uel C ell and E lectrolysis M odels D ialo g Box for the Coolan t Channel 1.Selec t the Advanc ed tab of the Fuel C ell and E lectrolysis M odels dialo g box. 2.Selec t Coolan t Channel under Advanc ed S etup . 3.Selec t an y numb er of c orresponding z ones fr om the Zone(s) list. 4.Specify a v alue f or the Densit y. 5.Specify a v alue f or the Heat Capacit y. 6.Specify a v alue f or the Thermal C onduc tivit y. 7.Specify a v alue f or the Visc osit y. 8.To enable the c oolan t channel, turn on the Enable C oolan t Channel(s) option. Amongst other settings , this will change the mix ture to include the c oolan t species , which is other wise absen t. 2461Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the F uel C ell and E lectrolysis M odel33.2.6.6.3. Managing Stacks for the F uel C ell and Elec trolysis Mo del Figur e 33.29: The A dvanc ed Tab of the F uel C ell and E lectrolysis M odels D ialo g Box for S tack Managemen t The ANSY S Fluen t Fuel C ell and E lectrolysis M odel allo ws you t o mo del fuel c ell stacks as w ell as individual fuel c ells. In the Advanc ed tab of the Fuel C ell and E lectrolysis M odels dialo g box, you can define fuel c ell units for each fuel c ell in a stack. A fuel c ell unit c onsists of all z ones of a single fuel c ell in the stack. Imp ortant If you ar e only mo deling a single fuel c ell, then y ou do not need t o set an ything f or Stack Managemen t in the Advanc ed tab of the Fuel C ell and E lectrolysis M odels dialo g box. 1.Selec t the Advanc ed tab of the Fuel C ell and E lectrolysis M odels dialo g box. 2.Selec t Stack M anagemen t under Advanc ed S etup . 3.Since a fuel c ell unit c onsists of all z ones of a single fuel c ell in the stack, selec t the c orresponding z ones from the Zone(s) list. 4.Create a new fuel c ell unit b y click ing the Create butt on.The new fuel c ell is list ed under Fuel C ell Unit(s) with a default name . 5.Edit a pr e-existing fuel c ell unit b y selec ting it in the Fuel C ell U nit(s) list. The z ones in this fuel c ell unit are aut oma tically selec ted in the Zone(s) list. You c an then mo dify the z ones tha t mak e up the fuel c ell unit and/or change its name in the Name field and click Modify to sa ve the new settings . 6.Remo ve a pr e-existing fuel c ell unit b y selec ting it in the Fuel C ell U nit(s) list and click ing the Delet e butt on. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2462Modeling F uel C ells7.If your mo del c ontains man y zone names , you c an use the Match Z one N ame P attern field t o sp ecify a pa ttern to look for in the names of z ones .Type the pa ttern in the t ext field and click Match to selec t (or deselec t) the z ones in the Zones list with names tha t ma tch the sp ecified pa ttern.You c an ma tch additional char acters using * and ?. For e xample , if you sp ecify wall* , all sur faces whose names b egin with wall (for e xample ,wall-1 ,wall-t op) will b e selec ted aut oma tically. If the y are all selec ted alr eady, they will b e deselec ted. If you sp ecify wall? , all sur faces whose names c onsist of wall followed b y a single char acter will b e selec ted (or deselec ted, if the y are all selec ted alr eady). For e xample , in a stack ther e ar e man y fuel c ells, say 10–100, each ha ving a t least 9 z ones (cur rent collec tor, gas channel, diffusion la yer, and c atalyst la yer for b oth ano de and c athode and a membr ane). Additionally , ther e ma y be coolan t channels , and it ma y be tha t for mesh c onstr uction reasons each of these ph ysical zones is made up of mor e than one mesh z one . Even f or small stacks , you c an easily end up ha ving hundr eds of c ell z ones in an ANSY S Fluen t mesh. Therefore, you ma y want to consider numb ering the fuel c ells in a stack and t o use the assigned fuel c ell numb er in the names of the mesh z ones .When y ou set up y our stack ed fuel c ell c ase, you w ould use the Match Z one N ame P attern field t o pick all the z ones b elonging t o a single fuel c ell in the stack, rather than scr olling thr ough the p otentially v ery long list and selec ting them manually . 8.You c an ha ve ANSY S Fluen t attempt t o aut oma tically det ermine the z ones tha t constitut e a single fuel cell in a stack using the Suggest S tack S etup butt on. Manually p erforming this task is of ten time-c on- suming and er ror-pr one . Using the Suggest S tack S etup butt on c an sa ve you fr om ha ving t o manually enter this inf ormation y ourself f or p otentially hundr eds of z ones . When using the Suggest S tack S etup butt on, ANSY S Fluen t needs t o correctly iden tify elec trically conduc ting par ts and their c onnec tivit y (ano de, elec trolyt e, cathode, coolan t channels , and e x- ternal c ontacts) using z one inf ormation gener ally r equir ed b y the fuel c ell mo del an yway. ANSY S Fluen t requir es z one inf ormation t o ha ve been sp ecified in all of the f ollowing tabs in the Fuel Cell and E lectrolysis M odels dialo g box: •In the Anode tab , specify z one inf ormation f or the cur rent collec tor, the p orous elec trode, and the TPB c atalyst la yer. •In the Electrolyt e tab , specify z one inf ormation f or the elec trolyt e/membr ane. •In the Catho de tab , specify z one inf ormation f or the cur rent collec tor, the p orous elec trode, and the TPB c atalyst la yer. •In the Advanc ed tab , specify z one inf ormation f or the c oolan t channel. •In the Rep orts tab , specify the e xternal c ontact interface(s). •In the Advanc ed tab , click the Suggest S tack S etup butt on. Imp ortant If your fuel c ell mo del inputs ar e inc orrect (or inc omplet e), ANSY S Fluen t cannot complet ely b e sur e tha t the r esulting setup is c orrect. Also, even if y our inputs ar e correct, an unc onventional fuel c ell design ma y cause ANSY S Fluen t to suggest an inaccur ate stack setup . So, it is y our r esponsibilit y to verify the stack setup pr ior t o click ing either the OK or the Apply butt ons. 2463Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the F uel C ell and E lectrolysis M odel33.2.6.7. Reporting on the S olution ( ReportsTab) You c an use the Rep orts tab of the Fuel C ell and E lectrolysis M odels dialo g box to set up par amet ers that will b e useful in r eporting da ta relevant to the fuel c ell. Figur e 33.30: The Rep orts Tab of the F uel C ell and E lectrolysis M odels D ialo g Box The Electrolyt e Projec ted A rea field r equir es the pr ojec ted ar ea of the M embr ane E lectrolyt e Assembly (MEA) and is only used t o calcula te the a verage cur rent densit y.The assembly c onsists of the membr ane and the c atalyst la yers ab ove and b elow the membr ane.The v alue of the pr ojec ted ar ea c an b e comput ed fr om the Projec ted S urface Areas dialo g box. Results → Rep orts → Projec ted A reas Edit... The External C ontact In terface(s) fields r equir es the fac e zones tha t act as e xternal c ontact sur faces for the ano de and the c athode. These inputs ar e used t o report cell v oltage . For p otentiosta tic b oundar y conditions , this is the diff er- ence between the pr ovided v alues , but f or galv anosta tic b oundar y conditions , the c ell v oltage is par t of the solution. 33.2.7. Modeling C urrent Collec tors In pr evious v ersions of ANSY S Fluen t, user-defined sc alar (UDS) equa tions c ould only b e solv ed in fluid zones .This r estriction is no w remo ved. As a r esult , the F uel C ell and E lectrolysis mo dule allo ws you t o model cur rent collec tors as solid , as w ell as fluid z ones . One ad vantage of using solids as the cur rent collec tor is tha t the c onvergenc e of the sp ecies equa tions ar e not hinder ed b y the p otentially sk ewed mesh inside the cur rent collec tors. If fluid z ones ar e used t o mo del solid cur rent collec tors, ANSY S Fluen t aut oma tically sets v elocities t o zero and cuts off sp ecies tr ansp ort into these z ones . If solid z ones ar e used , however, you need t o ac- tivate the solution of the elec tric potential (UDS-0) in these solid z ones (see the separ ate ANSY S Fluen t Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2464Modeling F uel C ellsUser’s Guide f or details). The v alue of the Electrical C onduc tivit y for the solid ma terial must b e assigned in the Create/Edit M aterials dialo g box. Figur e 33.31: The E lectric C onduc tivit y Field in the C reate/Edit M aterials D ialo g Box Imp ortant Note tha t the UDS D iffusivit y should b e set t o user-defined (cond::fuelcells ). Do not use the defined-per-uds option. For mor e inf ormation on the user-defined sc alar diffusivit y, see the separ ate ANSY S Fluen t User's Guide (p.1). Note tha t the F uel C ell and E lectrolysis M odel allo ws you t o mo del cur rent collec tors either as p orous media z ones (if y ou w ant to allo w for mass and momen tum tr ansp ort within the c ollec tors) or as solid zones . 33.2.8. Fuel C ell and E lectrolysis M odel B oundar y Conditions The f ollowing b oundar y conditions need t o be defined f or the F uel C ell and E lectrolysis simula tion based on y our pr oblem sp ecific ation: •Anode Inlet –Mass flo w rate –Temp erature –Direction sp ecific ation metho d –Mass fr actions (f or e xample ,h2, and h2o ). 2465Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the F uel C ell and E lectrolysis M odel–The c oolan t must be set t o zero if c oolan t channels ar e enabled . –UDS-2 ( Water Saturation) must b e set t o 0 •Cathode Inlet –Mass flo w rate –Temp erature –Direction sp ecific ation metho d –Mass fr actions (f or e xample o2,h2o , and n2). –The c oolan t must be set t o zero if c oolan t channels ar e enabled . –UDS-2 ( Water Saturation) must b e set t o 0 •Coolan t Inlet (if an y) –Mass flo w rate –Temp erature –Direction sp ecific ation metho d –Coolan t mass fr action set t o 1 –UDS-2 ( Water Saturation) must b e set t o 0 •Pressur e Outlets (all) Realistic backflo w conditions . •Terminal A node –Temp erature (or flux if k nown) –UDS-0 (elec tric potential) set t o gr ound v oltage •Terminal C athode –Temp erature (or flux if k nown) –UDS-0 (elec tric potential) is set t o the v oltage of the c athode (if solving t o constan t voltage), or the UDS- 0 (elec tric potential) flux is set t o the cur rent densit y in (SI units) (if solving f or constan t cur rent). Note tha t the sign of the UDS-0 flux on the c athode side is nega tive. 33.2.9. Solution G uidelines f or the F uel C ell and E lectrolysis M odel For p otentiosta tic b oundar y conditions , after initializa tion, steady-sta te solutions ar e calcula ted easily for c ell v oltages close t o the op en-cir cuit v oltage .The same c an b e said f or galv anosta tic b oundar y conditions and lo w elec tric cur rent. By lowering the c ell v oltage or b y raising the a verage elec tric current, you c an c alcula te subsequen t sta tionar y solutions . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2466Modeling F uel C ellsIn the e vent of c onvergenc e pr oblems , it is r ecommended tha t you change the multigr id cycle t o F- cycle with BCGST AB (bi-c onjuga te gr adien t stabiliz ed metho d) selec ted as the stabiliza tion metho d for the sp ecies and the t wo potential equa tions . For the sp ecies and the user-defined sc alar equa tions , it ma y be nec essar y to reduc e the t ermina tion (cr iteria) of the multigr id-c ycles t o . For stack simula tions , the t ermina tion cr iterion ma y be reduc ed t o for the t wo potential equa tions . Also, it ma y be useful t o tur n off Joule H eating and Reac tion H eating in the Fuel C ell and E lectro- lysis M odels dialo g box (in the Model tab) f or the first f ew (appr oxima tely 5-10) it erations af ter initial- ization. This allo ws the t wo elec tric potentials t o adjust fr om their initial v alues t o mor e ph ysical values , avoiding the p ossibilit y of e xtreme elec trochemic al reactions and elec tric cur rents tha t would in tur n adversely impac t the solution. 33.2.10. Postpr ocessing the F uel C ell and E lectrolysis M odel You c an p erform p ostpr ocessing using standar d ANSY S Fluen t quan tities and b y using user-defined scalars and user-defined memor y allo cations . By default , the ANSY S Fluen t Fuel C ell and E lectrolysis Model defines se veral user-defined sc alars and user-defined memor y allo cations , descr ibed in Table 33.3: User-D efined Sc alar A llocations (p.2467 ) and Table 33.4: User-D efined M emor y Alloca- tions (p.2467 ). Table 33.3: User-D efined Sc alar A llocations Electric Potential (solid phase p otential) ( Volts) UDS 0 Protonic P otential (membr ane phase p otential) ( Volts) UDS 1 Water S aturation (liquid sa turation) UDS 2 Water C ontent UDS 3 Table 33.4: User-D efined M emor y Allocations X Current Flux D ensit y ( )UDM 0 Y Current Flux D ensit y ( )UDM 1 Z Current Flux D ensit y ( )UDM 2 Current Flux D ensit y Magnitude ( )UDM 3 Ohmic H eat Source ( )UDM 4 Reaction H eat Source ( )UDM 5 Overpotential ( Volts) UDM 6 Phase C hange S ource ( )UDM 7 Osmotic D rag C oefficien t UDM 8 Liquid Water A ctivit y UDM 9 Membr ane Water C ontent UDM 10 Protonic C onduc tivit y (1/ohm-m) UDM 11 Back D iffusion M ass S ource ( )UDM 12 2467Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the F uel C ell and E lectrolysis M odelTransf er C urrent ( )UDM 13 Osmotic D rag S ource ( )UDM 14 You c an obtain this list b y op ening the Execut e On D emand dialo g box and pulling do wn the Func tion drop-do wn list. User D efined → User D efined → Execut e on D emand ... and acc ess the e xecut e-on-demand func tion c alled list_pemfc_udf . Alternatively, you c an view the listing tha t app ears when y ou first load y our F uel C ell and E lectrolysis case, or y ou c an t ype list_pemfc_udf in the t ext user in terface and the listing will app ear in the console windo w. Note •For field v ariables tha t are stored in UDM, use the c orresponding v ariables f or p ostpr o- cessing . Postpr ocessing the UDM itself is not r ecommended . •For reviewing simula tion r esults in CFD-P ost f or cases in volving UDM or UDS, export the solution da ta as CFD-P ost-c ompa tible file (.cdat ) in F luen t and then load this file in to CFD-P ost. Imp ortant When y ou load older F uel C ell and E lectrolysis c ases in to ANSY S Fluen t, and y ou ar e monit- oring a UDS using v olume or sur face monit ors, mak e sur e you r e-visit the c orresponding monit ors dialo g box (for e xample , the Volume M onit or or the Surface M onit or dialo g box) to verify tha t the c orrect UDS name is used f or the appr opriate monit or. 33.2.11. User-A ccessible F unc tions As not ed in Properties, you c an dir ectly inc orporate your o wn f ormula tions and da ta for the pr operties of the fuel c ell membr ane using the pem_user.c sour ce code file . The f ollowing listing r epresen ts a descr iption of the c ontents of the pem_user.c sour ce code file: real Get_P_sat(real T, cell_t c, Thread *t) Retur ns the v alue of the w ater vapor sa turation pr essur e as a func tion of t emp erature (Equa tion 25.91 ) or other user-sp ecified v alues . real Water_Activity(realP, realT, cell_t c, Thread *t) Retur ns the v alue of w ater ac tivit y (Equa tion 25.89 ). real Water_Content(real act) Retur ns the v alue of the membr ane w ater content at the membr ane c atalyst in terface (Equa tion 25.88 ). real Osmotic_Drag_Coefficient(real P, real T, cell_t c, Thread *t) Retur ns the v alue of the osmotic dr ag c oefficien t (Equa tion 25.85 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2468Modeling F uel C ellsreal Membrane_Conductivity(real lam, cell_t c, Thread *t) Retur ns the v alue of the membr ane’s protonic c onduc tivit y (Equa tion 25.84 ). real Electrolyte_Conductivity(cell_t c, Thread *t) Retur ns the v alue of the ionic c onduc tivit y in the elec trolyt e (Equa tion 25.83 ). (SOFC and E lectrolysis only) real Water_Content_Diffusivity(real lam, real T, real mem_mol_dens- ity,cell_tc,Thread*t) Retur ns the v alue of the w ater content diffusivit y in the membr ane ( Equa tion 25.87 ). real Gas_Diffusivity(cell_tc, Thread *t, int j_spe) Retur ns the v alue of the gaseous sp ecies diffusivities in the channels , gas diffusion la yers and c atalysts (Equa tion 25.80 ). real MCD_Gas_Diffusivity(cell_t c, Thread *t, int i) Retur ns the t ortuosit y-corrected v alue of the gas sp ecies diffusion c oefficien ts comput ed with the mul- ticomp onen t diffusion option ( Equa tion 25.82 ). real Saturation_Diffusivity(real sat, real cos_theta, real porosity, cell_t c, Thread *t) Retur ns the v alue of diffusivit y of the liquid sa turation. It comput es the t erm from Equa tion 25.76 . real Anode_AV_Ratio(cell_t c, Thread *t) Retur ns the v alue of the sp ecific ac tive sur face area ( in Equa tion 25.59 ) for the ano de c atalyst. real Cathode_AV_Ratio(cell_t c, Thread *t) Retur ns the v alue of the sp ecific ac tive sur face area ( in Equa tion 25.60 ) for the c athode c atalyst. real Anode_J_TransCoef(cell_t c, Thread *t) Retur ns the v alue of the ano de r eaction r eference cur rent densit y used in Equa tion 25.59 . real Cathode_J_TransCoef(cell_t c, Thread *t) Retur ns the v alue of the c athode r eaction r eference cur rent densit y used in Equa tion 25.60 . real Open_Cell_Voltage(cell_t c, Thread *t) Retur ns the v alue of the op en-cir cuit v oltage used in Equa tion 25.64 . real Leakage_Current(cell_t c, Thread *t) Retur ns the v alue of the leak age cur rent ( in Equa tion 25.92 through Equa tion 25.97 ). void Set_UDS_Names(char uds[n_uds_required][STRING_SIZE]) Used t o rename user defined sc alars (UDSs). Note tha t the units of the user defined sc alars c annot b e changed . void Set_UDS_Names(char uds[n_uds_required][STRING_SIZE]) { strncpy(uds[0], "Electric Potential", STRING_SIZE-1); strncpy(uds[1], "Protonic Potential", STRING_SIZE-1); strncpy(uds[2], "Water Saturation", STRING_SIZE-1); strncpy(uds[3], "Water Content", STRING_SIZE-1); } 2469Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the F uel C ell and E lectrolysis M odelIf you w ant to change the names of UDSs , change the sec ond ar gumen t of the strncpy func tions , recompile and link the mo dule as with an y mo dific ation t o pem_user.c . Note tha t STRING_SIZE is fix ed in pem.h and should not b e changed . Imp ortant When y ou load older F uel C ell and E lectrolysis c ases in to ANSY S Fluen t, and y ou ar e monit oring a UDS using v olume or sur face monit ors, mak e sur e you r e-visit the c orres- ponding monit ors dialo g box (for e xample , the Volume M onit or or the Surface M onit or dialo g box) to mak e sur e tha t the c orrect UDS name is used f or the appr opriate monit or. void Set_UDM_Names(char udm[n_udm_required][STRING_SIZE]) Used t o rename user defined memor y (UDMs). Note tha t the units of user defined memor y cannot b e changed . void Set_UDM_Names(char udm[n_udm_required][STRING_SIZE]) { strncpy(udm[0], "X Current Flux Density", STRING_SIZE-1); strncpy(udm[1], "Y Current Flux Density", STRING_SIZE-1); strncpy(udm[2], "Z Current Flux Density", STRING_SIZE-1); strncpy(udm[3], "Current Flux Density Magnitude", STRING_SIZE-1); strncpy(udm[4], "Ohmic Heat Source", STRING_SIZE-1); strncpy(udm[5], "Reaction Heat Source", STRING_SIZE-1); strncpy(udm[6], "Overpotential", STRING_SIZE-1); strncpy(udm[7], "Phase Change Source (PEM)", STRING_SIZE-1); strncpy(udm[8], "Osmotic Drag Coefficient (PEM)", STRING_SIZE-1); strncpy(udm[9], "Liquid Water Activity (PEM)", STRING_SIZE-1); strncpy(udm[10], "Membrane Water Content (PEM)", STRING_SIZE-1); strncpy(udm[11], "Protonic Conductivity", STRING_SIZE-1); strncpy(udm[12], "Back Diffusion Source (PEM)", STRING_SIZE-1); strncpy(udm[13], "Transfer Current", STRING_SIZE-1); strncpy(udm[14], "Osmotic Drag Source (PEM)", STRING_SIZE-1); } If you w ant to change the names of UDMs , change the sec ond ar gumen t of the strncpy func tions , recompile and link the mo dule as with an y mo dific ation t o pem_user.c . Note tha t STRING_SIZE is fix ed in pem.h and should not b e changed . Imp ortant When y ou load older F uel C ell and E lectrolysis c ases in to ANSY S Fluen t, and y ou ar e monit oring a UDM using v olume or sur face monit ors, mak e sur e you r e-visit the c orres- ponding monit ors dialo g box (for e xample , the Volume M onit or or the Surface M onit or dialo g box) to mak e sur e tha t the c orrect UDM name is used f or the appr opriate monit or. real electric_contact_resistance(face_t f, Thread *t, int ns) Retur ns the v alue f or the elec trical contact resistanc e. real Transfer_Current(real i_ref, real gamma, int species_i, real alpha_a, real alpha_c, real *dRade, real *dRcde, Thread *t, cell_t c) Comput es the tr ansf er cur rent ( ), corresponding t o in Equa tion 25.59 and in Equa tion 25.60 . Inputs f or this func tion include: effective transf er cur rent coefficien t, comput ed b y Cathode_J_TransCoef(c,t) or Anode_J_TransCoef(c,t)i_ref Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2470Modeling F uel C ellscathode or ano de c oncentration e xponen t gamma species inde x used in fuel c ells (f or e xample i_o2 , i_h2,i_h2o ) species_i produc t of ano de e xchange c oefficien t and alpha_a produc t of c athode e xchange c oefficien t and alpha_c current thr ead t current cell c Outputs f or this func tion include: ano de or c athode v olumetr ic tr ansf er cur rent ( in Equa tion 25.59 or in Equa tion 25.60 )source partial der ivative of with r espect to ac tivation loss *dRade partial der ivative of with r espect to ac tivation loss *dRcde Thermal_ctk_pemfc(face_t f, Thread *t) Used t o change the c onstan t value of Thermal C ontact Resistanc e for the p orous z one set in the Porous Jump dialo g box to a lo cally v ariable v alue . For mor e inf ormation, see the f ollowing sec tions: 33.2.11.1. Compiling the C ustomiz ed F uel C ell and E lectrolysis S ource Code 33.2.11.1. Compiling the C ustomiz ed F uel C ell and Elec trolysis S our ce Code This sec tion includes instr uctions on ho w to compile a cust omiz ed F uel C ell and E lectrolysis user- defined mo dule . Imp ortant It is assumed tha t you ha ve a basic familiar ity with c ompiling user-defined func tions (UDFs). For an in troduc tion on ho w to compile UDFs , refer to the Fluen t Customiza tion M anual . You will first w ant to use a lo cal copy of the fuelcells directory in the addons directory before you r ecompile the F uel C ell and E lectrolysis mo dule . 33.2.11.1.1. Compiling the C ustomiz ed S our ce Code Under Linux 1.Make a lo cal copy of the fuelcells directory. Do not cr eate a symb olic link. Imp ortant The cust om v ersion of the libr ary must b e named acc ording t o the c onvention used by ANSY S Fluen t: for e xample ,fuelcells . 2.Change dir ectories t o the fuelcells/src directory. 3.Make changes t o the pem_user.c file. 2471Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the F uel C ell and E lectrolysis M odel4.Define the FLUENT_ADDONS environmen t variable t o correspond t o your cust omiz ed v ersion of the Fuel C ell and E lectrolysis mo dule . 5.Change dir ectories t o the fuelcells/ directory. 6.Issue the f ollowing make command: make FLUENT_INC=[ansys_inc/v195/fluent] FLUENT_ARCH=[arch] -f Makefile-client wher e your_arch is lnx86 on LINUX, or ultra on the Sun op erating sy stem, and so on. The f ollowing e xample demonstr ates the st eps r equir ed t o set up and r un a cust omiz ed v ersion of the F uel C ell and E lectrolysis mo dule tha t is lo cated in a f older c alled home/sample : •Make a dir ectory (for e xample ,mkdir -p /home/sample ). •Copy the default addon libr ary to this lo cation. cp -RH [ansys_inc/v195/fluent]/fluent19.5.0/addons/fuelcells /home/sample/fuelcells •Using a t ext edit or, mak e the appr opriate changes t o the pem_user.c file lo cated in /home/sample/fuelcells/src/pem_user.c •Build the libr ary. cd /home/sample/fuelcells make FLUENT_INC=[ansys_inc/v195/fluent] FLUENT_ARCH=[arch] -f Makefile-client •Set the FLUENT_ADDONS environmen t variable (using CSH, other shells will diff er). setenv FLUENT_ADDONS /home/sample •Start ANSY S Fluen t and load the cust omiz ed mo dule using the t ext interface command . 33.2.11.1.2. Compiling the C ustomiz ed S our ce Code Under Windo ws 1.Open Visual S tudio .NET at the DOS pr ompt. 2.Make sur e tha t the $FLUENT_INC environmen t variable is c orrectly set t o the cur rent ANSY S Fluen t installa tion dir ectory (for e xample ,ANSYS Inc\v195\fluent ). 3.Make a lo cal copy of the fuelcells folder . Do not cr eate a shor tcut. 4.Enter the fuelcells\src folder . 5.Make changes t o the pem_user.c file. 6.Define the FLUENT_ADDONS environmen t variable t o correspond t o your cust omiz ed v ersion of the Fuel C ell and E lectrolysis mo dule . 7.Retur n to the fuelcells folder . 8.Issue the f ollowing c ommand in the c ommand windo w: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2472Modeling F uel C ells nmake /f makefile_master-client.nt 33.3. Using the S olid O xide F uel C ell With U nresolv ed E lectrolyt e M odel The pr ocedur e for setting up and solving solid o xide fuel c ell (SOFC) pr oblems (with unr esolv ed elec tro- lyte) is descr ibed in detail in this chapt er. Refer to the f ollowing sec tions f or mor e inf ormation: 33.3.1. Limita tion on M odeling S olid O xide F uel C ells 33.3.2. Installing the S olid O xide F uel C ell With U nresolv ed E lectrolyte Model 33.3.3. Loading the S olid O xide F uel C ell With U nresolv ed E lectrolyte Module 33.3.4. Solid O xide F uel C ell With U nresolv ed E lectrolyte Module S et U p Procedur e 33.3.5. Setting the P aramet ers f or the SOFC With U nresolv ed E lectrolyte Model 33.3.6. Setting U p the E lectrochemistr y Paramet ers 33.3.7. Setting U p the E lectrode-E lectrolyte Interfaces 33.3.8. Setting U p the E lectric Field M odel P aramet ers 33.3.9. User-A ccessible F unctions f or the S olid O xide F uel C ell With U nresolv ed E lectrolyte Model 33.3.1. Limita tion on M odeling S olid O xide F uel C ells The anisotr opic sp ecies diffusivit y option is not c ompa tible with the S olid O xide F uel C ell mo del. 33.3.2. Installing the S olid O xide F uel C ell With U nresolv ed E lectrolyt e Model The S olid O xide F uel C ell (SOFC) With U nresolv ed E lectrolyt e M odel is pr ovided as an addon mo dule with the standar d ANSY S Fluen t licensed sof tware.The mo dule is installed with the standar d installa tion of ANSY S Fluen t in a dir ectory called addons/sofc in y our installa tion ar ea.The SOFC With U nresolv ed Electrolyt e M odel c onsists of a UDF libr ary and a pr e-compiled Scheme libr ary, tha t must b e loaded and ac tivated b efore calcula tions c an b e performed . 33.3.3. Loading the S olid O xide F uel C ell With U nresolv ed E lectrolyt e Module The S olid O xide F uel C ell (SOFC) With U nresolv ed E lectrolyt e M odel is loaded in to ANSY S Fluen t thr ough the t ext user in terface (TUI). The mo dule c an only b e loaded af ter a v alid ANSY S Fluen t mesh or c ase file has b een set or r ead.The t ext command t o load the addon mo dule is define → models → addon-module A list of ANSY S Fluen t addon mo dules is displa yed: > /define/models/addon-module Fluent Addon Modules: 0. None 1. MHD Model 2. Fiber Model 3. Fuel Cell and Electrolysis Model 4. SOFC Model with Unresolved Electrolyte 5. Population Balance Model 6. Adjoint Solver 7. Battery Module 8. MSMD Battery Model 9. PEM Fuel Cell Model Enter Module Number: [0] 4 2473Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the S olid O xide F uel C ell With U nresolv ed E lectrolyte ModelSelec t the SOFC With U nresolv ed E lectrolyt e M odel b y en tering the mo dule numb er 4. During the loading pr ocess, a Scheme libr ary (containing the gr aphic al and t ext user in terface) and a UDF libr ary (containing a set of user defined func tions) ar e loaded in to ANSY S Fluen t. Onc e the mo dule has b een loaded , the SOFC M odel (U nresolv ed E lectrolyt e) option app ears in the tree under the Models branch and in the Models task page . To enable the SOFC mo del: In the Outline View under the Models branch, right-click Fuel C ells and Electrolysis and selec t Edit... in the menu tha t op ens. Setup → Models → SOFC M odel (U nresolv ed E lectrolyt e) Edit... Figur e 33.32: Op ening the SOFC M odel D ialo g Box in the Outline View When the SOFC M odel dialo g box app ears , selec t the Enable SOFC M odel option. 33.3.4. Solid O xide F uel C ell With U nresolv ed E lectrolyt e M odule S et U p Procedur e The f ollowing descr ibes an o verview of the pr ocedur e requir ed in or der t o use the SOFC With U nresolv ed Electrolyt e M odel in ANSY S Fluen t. 1.Start ANSY S Fluen t. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2474Modeling F uel C ellsYou must star t ANSY S Fluen t in 3D double-pr ecision mo de. Note tha t the SOFC With U nresolv ed Electrolyt e M odel is only a vailable in 3D . 2.Read the c ase file . File → Read → Case... 3.Scale the mesh. Setup → Gener al → Scale... 4.Define v arious mo del par amet ers f or the simula tion. a.Check the solv er settings . Setup → Gener al i.In the Solver group b ox, enable Pressur e Based under Type. ii.Enable Stead y under Time . iii.Enable Absolut e under Velocity Formula tion . b.In the Energy dialo g box, enable the Energy option (if it is not alr eady enabled). Setup → Models → Energy ON c.In the Visc ous M odel dialo g box, enable the Laminar option (if it is not alr eady enabled). Setup → Models → Visc ous Edit... d.In the Species M odel dialo g box, configur e the f ollowing settings: Setup → Models → Species Edit... i.Enable the Species Transp ort option. ii.Enable the Volumetr ic option under Reac tions (see Enabling S pecies Transp ort and R eactions and C hoosing the M ixture Material in the Fluent U ser's G uide (p.1616 ) for details). iii.From the Mixture M aterial drop-do wn list , selec t an appr opriate mix ture ma terial or cr eate your own mix ture ma terial fr om mixture-template as descr ibed in Enabling S pecies Transp ort and Reactions and C hoosing the M ixture Material in the Fluent U ser's G uide (p.1616 ). If you c onsider H2/CO elec trochemistr y, ensur e tha t your mix ture ma terial include H2, CO and C O2. iv.Disable the Inlet D iffusion option under Options (see Diffusion a t Inlets in the Fluent Theor y Guide ). v.Enable the Diffusion E nergy Sour ce option under Options (see Treatmen t of S pecies Transp ort in the Ener gy Equa tion in the Fluent Theor y Guide ). vi.Enable the Full M ultic omp onen t Diffusion option under Options (see Mass D iffusion in Laminar Flows in the Fluent Theor y Guide ). 2475Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the S olid O xide F uel C ell With U nresolv ed E lectrolyte Modelvii.Enable the Thermal D iffusion option under Options (see Mass D iffusion in Laminar F lows in the Fluent Theor y Guide ). e.Enable the SOFC M odel mo del and set the par amet ers f or the SOFC with unr esolv ed elec trolyt e model: Setup → Models → SOFC M odel (U nresolv ed E lectrolyt e) Edit... i.In the Model P aramet ers tab , set the Current Under-Relaxa tion F actor to a v alue of either 0.3 or 0.4 . ii.Under Model Options , selec t the appr opriate SOFC mo del options . iii.Set the Electrical and E lectrolyt e Paramet ers acc ording t o your pr oblem sp ecific ation. iv.Selec t the Enable S urface Energy Sour ce option, the Enable S pecies S our ces option, and the Disable C O Electrochemistr y option. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2476Modeling F uel C ellsIf the elec trolyt e resistivit y changes as a func tion of t emp erature, then tur n on the Enable Electrolyt e Conduc tivit y Submo del Table 33.5: User-D efined M emor y Allocations Interface Current Densit y ( )UDM-0 Nernst P otential ( Volts) UDM-1 Activation O verpotentail ( Volts) UDM-2 Volumetr ic O hmic S ource ( )UDM-3 x Comp onen t of the C urrent Densit y ( )UDM-4 y Comp onen t of the C urrent Densit y ( )UDM-5 z Comp onen t of the C urrent Densit y ( )UDM-6 Electrolyt e Voltage J ump UDM-7 Electrolyt e Resistivit y (O hm-m) UDM-8 Effective Electric Resistanc e UDM-9 Anode A ctivation UDM-10 Cathode A ctivation UDM-11 Electrochemic al Source ( )UDM-12 Magnitude of C urrent Densit y ( )UDM-13 Note tha t UDM-7 and UDM-8 are the linear ized v alues tha t ANSY S Fluen t uses t o solv e the potential field and elec trochemic al coupling .They are nec essar y to the c alcula tions but do not c ontain an y real ph ysical meaning . Note tha t UDM-10 and UDM-11 contain the disaggr egated ac tivation p olar izations a t the ano de and c athode. f.In the Electrochemistr y tab , set the elec trochemistr y par amet ers. 2477Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the S olid O xide F uel C ell With U nresolv ed E lectrolyte Modeli.Enter values f or the Constan t Exchange C urrent Densities for the ano de and the c athode.These are the values in the B utler-V olmer equa tion ( Equa tion 25.114 ) for the ano dic and c athodic r eac- tions . By default , the Anode E xchange C urrent Densit y is set t o 1000 Amps and the Catho de Exchange C urrent Densit y is set t o 100 Amps . ii.Enter values f or the Mole F raction Ref erenc e Values . These ar e the sp ecies c oncentrations a t which the e xchange cur rent densities w ere tak en (Equa tion 25.115 -Equa tion 25.117 ).These ar e used t o adjust the values of r eactant sp ecies that are deplet ed. By default , the H2 Ref erenc e Value is set t o 0.8 moles/moles , the O2 Referenc e Value is set t o 0.21 moles/moles , and the H2O Ref erenc e Value is set t o 0.2 moles/moles . iii.Enter values f or the Stoichiometr ic Exponen ts by setting v alues f or the H2 E xponen t, the H20 Exponen t, and the O2 E xponen t (default ed t o 0.5 ).These ar e the st oichiometr ic fac tors in the elec trochemic al reaction equa tion. They are used as e xponen ts as par t of the scaling ( Equa- tion 25.116 and Equa tion 25.117 . iv.Enter values f or the Butler-V olmer Transf er C oefficien ts by setting v alues f or the Anodic Transf er C oefficien t ( in Equa tion 25.114 ) and the Catho de Transf er C oefficien t ( in Equa- tion 25.114 ) for b oth the ano de r eaction and the c athode r eaction (default ed t o 0.5 ).These ar e Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2478Modeling F uel C ellsthe alpha v alues in the B utler-V olmer equa tion ( Equa tion 25.114 ).They represen t the f orward and back ward rates of r eaction a t both the ano de and c athode. v.Enter values f or the Temp erature Dependen t Exchange C urrent Densit y by tur ning on the Enable Temp erature Dependen t I_0 option and setting v alues f or A and B (Equa tion 33.4 (p.2486 )).These two coefficien ts allo w the for the c athode t o vary as a func tion of t emp erature. g.In the Electrode and Tortuosit y tab , set the ano de and c athode in terface comp onen ts and set the tortuosit y par amet ers f or the SOFC With U nresolv ed E lectrolyt e Model. i.Under Anode E lectrolyt e, selec t a z one in the Zone(s) list and enable Anode In terface if it is ap- plicable . ii.Do the same f or Catho de E lectrolyt e and Tortuosit y Zone . h.In the Electric Field tab , set the par amet ers f or the elec tric field mo del. 2479Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the S olid O xide F uel C ell With U nresolv ed E lectrolyte Modeli.Selec t up t o 5 c onduc tive regions . ii.Selec t up t o 3 c ontact sur faces. iii.Selec t a v oltage tap sur face. iv.Selec t a cur rent tap sur face. 5.Define ma terial pr operties. a.Create or r e-define new solid ma terials as appr opriate for the ano de, the c athode, and the elec trolyt e according t o your pr oblem sp ecific ation. Imp ortant Note tha t although the ANSY S Fluen t SOFC With U nresolv ed E lectrolyt e M odel do es supp ort the shell c onduc tion mo del tha t you use t o tak e in to acc oun t the tr ansv ersal conduc tive hea t inside the elec trolyt e ma terial, it do es not cur rently supp ort a similar ly transv ersal c onduc tion of elec tric cur rent inside the elec trolyt e. b.Edit the mix ture-templa te mix ture ma terial. Setup → Materials → Create/Edit... i.In the Create/Edit M aterials dialo g box, click Fluen t Database ... to op en the Fluen t Database Materials dialo g box. ii.In the Fluen t Database M aterials dialo g box, mak e a c opy of the h2 fluid ma terial. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2480Modeling F uel C ellsiii.In the Create/Edit M aterials dialo g box, change the Material Type to mixture and click Edit... for the Mixture Species . iv.In the Species dialo g box, arrange the ma terials under Selec ted S pecies in the f ollowing or der: h2o ,o2,h2, and n2. (The sp ecies or dering is not imp ortant as long as n2 is the last sp ecies .) v.In the Create/Edit M aterials dialo g box, change the Thermal C onduc tivit y and the Visc osit y to ideal-gas-mixing-la w. vi.Change the Mass D iffusivit y to user-defined and selec t diffusivit y::sof c as the c orresponding user-defined func tion. vii.Change the UDS D iffusivit y to user-defined and selec t E_C onduc tivit y::sof c as the c orresponding user-defined func tion. viii.Retain the default v alues f or the other par amet ers and click Change/C reate. 6.Set the op erating c onditions . Setup → Boundar y Conditions → Operating C onditions ... Retain the default v alues . 7.Set the b oundar y conditions . Setup → Boundar y Conditions Define the c onditions a t the ano de, the c athode, the in terface between the ano de and cur rent collec tor, the in terface between the c athode and the cur rent collec tor, the ano de inlet , and the cathode inlet b oundar ies acc ording t o your pr oblem sp ecific ation. Note tha t sour ces only need t o be ho oked t o the mass , species , and ener gy equa tion in a single fluid z one in or der f or the ANSY S Fluen t SOFC With U nresolv ed E lectrolyt e M odel t o func tion properly (but c an b e ho oked t o all z ones if y ou so cho ose). ANSY S Fluen t do es not r ely on c ell or thread r eferencing in the sour ces in or der t o cover the solution domain. 8.Set the multigr id control par amet ers. Solution → Controls Advanc ed... a.In the Multigr id tab of the Advanc ed S olution C ontrols dialo g box, set the c ycle t ype for h2,h2o , and o2 to V-cycle. For ser ial c alcula tions , set the c ycle t ype for Energy and User-defined Sc alar-0 to W-c ycle or F-cycle. For par allel c alcula tions , selec t the F-cycle option f or b oth. b.Set the Max C ycles to 50. c.Retain the default v alues f or the r est of the par amet ers. 9.Define the c onvergenc e criteria. Solution → Monit ors → Residuals Edit... In the Residual M onit ors dialo g box, set the Convergenc e Criterion for all equa tions t o 1e-08 . 2481Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the S olid O xide F uel C ell With U nresolv ed E lectrolyte Model10.Initializ e the flo w field . Solution → Initializa tion → Initializ e Retain the default v alues f or all par amet ers. The cur rent densit y in UDM-0 is a c onser vative flux of elec tricity ( ). Performing an ar ea in tegral over the elec trolyt e sur face will sum t o the t otal cur rent ( ).That value is c omput ed a t the elec trolyt e faces dur ing the elec tric field solution. The v alues in UDM-4 through UDM-6 contain c ell-c entered values of the cur rent densit y vector.These ar e not , and c annot b e, conser vative, so dep ending on the material c onduc tivit y and the geometr ic configur ation, these c an sometimes una voidably pr oduce values tha t do not ma tch the UDM v alues .The same issues e xist when in terpolating v elocity values to obtain the mass flux es. Note tha t, by default , the ANSY S Fluen t SOFC With U nresolv ed E lectrolyt e M odel defines a single user- defined sc alar: Table 33.6: User-D efined Sc alar A llocations Electric Potential ( Volts) UDS-0 Note •For field v ariables tha t are stored in UDM, use the c orresponding v ariables f or p ost pr o- cessing . Postpr ocessing the UDM itself is not r ecommended . •For reviewing simula tion r esults in CFD-P ost f or cases in volving UDM or UDS, export the solution da ta as CFD-P ost-c ompa tible file (.cdat ) in F luen t and then load this file in to CFD-P ost. 33.3.5. Setting the P aramet ers f or the SOFC With U nresolv ed E lectrolyt e Model You c an sp ecify the gener al settings f or the SOFC With U nresolv ed E lectrolyt e M odel using the Model Paramet ers tab in the SOFC M odel dialo g box. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2482Modeling F uel C ellsFigur e 33.33: The M odel P aramet ers Tab in the SOFC M odel D ialo g Box From this tab , you c an set the v arious par amet ers f or the SOFC With U nresolv ed E lectrolyt e M odel such as t otal sy stem cur rent, elec trolyt e thick ness , elec trolyt e resistivit y, and so on. The Enable E lectrolyt e Conduc tivit y Submo del option allo ws the ionic c onduc tivit y (or r esistivit y) of the elec trolyt e to change as a func tion of t emp erature. At the momen t, ther e is one c orrelation tha t provides ionic c onduc tivit y (or r esistivit y) of the elec trolyt e as func tion of t emp erature. (33.2) Imp ortant Note tha t this is v alid only f or temp eratures ranging fr om 1073 K t o 1373 K. By tur ning off the Enable S urface Energy Sour ce option, ANSY S Fluen t excludes the hea t addition due t o elec trochemistr y and all the r eversible pr ocesses .This option should b e tur ned on a t all times . 2483Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the S olid O xide F uel C ell With U nresolv ed E lectrolyte ModelThe Enable Volumetr ic E nergy Sour ce option includes the ohmic hea ting thr oughout the elec trically conduc ting z ones .You should k eep this option tur ned off (t o avoid slo wing the c onvergenc e rates) until a c ertain r ate of c onvergenc e for the p otential field has b een achie ved, at which p oint, you should turn the option on manually . Note tha t this option is imp ortant so tha t the solution c an acc oun t for the eff ects of the in ternal O hmic hea ting . The Disable C O E lectrochemistr y is enabled if ther e is c arbon mono xide (C O) in the fuel line and if you do not w ant to include the C O in the elec trochemistr y. Since the c alcula tions ar e very sensitiv e to lar ge cur rent fluc tuations ear ly in the solution pr ocess, it is recommended tha t you use 0.3 or 0.4 for the Current Under-Relaxa tion F actor for a mor e eff ective solution. The leak age cur rent is the t otal amoun t of cur rent due t o the leak age of o xidiz er to the fuel side (through the elec trolyt e) and the elec tric cur rent acr oss the elec trolyt e due t o an y shor t cir cuit. You can sp ecify a v alue f or the leak age cur rent under Leak age C urrent Densit y. If the leak age cur rent densit y is t emp erature-dep enden t, you c an sp ecify y our o wn t emp erature-de- penden t implemen tation of the leak age cur rent densit y by performing the f ollowing st eps: 1.Make the r equir ed changes t o Leakage_Current_Density (real T) which is a r eal func tion in the user-mo difiable sour ce code,constit.c . 2.Compile constit.c and mak e your o wn sofc UDF libr ary. For mor e inf ormation, see Compiling the C ustomiz ed S olid O xide F uel C ell With U nresolv ed E lec- trolyt e Source Code (p.2490 ). The Converge t o Specified S ystem Voltage is used when y ou w ant to sp ecify a sy stem v oltage inst ead of sy stem cur rent as an input. The Set Individual E lectrical B oundar y Condition fr om B oundar y Conditions Task P age option, when enabled , allo ws you t o dir ectly sp ecify the cur rent densit y or v oltage f or each individual cur rent- collec ting b oundar y using the ANSY S Fluen t Boundar y Conditions task page .This allo ws you t o apply multiple cur rent types or multiple v oltage t ypes (either c onstan t or v ariable) t o your b oundar y conditions . 33.3.6. Setting U p the E lectrochemistr y Paramet ers You c an sp ecify elec trochemistr y settings f or the SOFC With U nresolv ed E lectrolyt e M odel using the Electrochemistr y tab in the SOFC M odel dialo g box. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2484Modeling F uel C ellsFigur e 33.34: The E lectrochemistr y Tab in the SOFC M odel D ialo g Box In the Electrochemistr y tab , you c an set the ano de and c athode e xchange cur rent densit y, the ano de and c athode mole fr action r eference values , the c oncentration e xponen ts, the B utler-V olmer tr ansf er coefficien ts, and the t emp erature-dep enden t exchange cur rent densit y. You c an sp ecify a v alue f or the e xchange cur rent densit y at the ano de (the default v alue is 1000 ) using the Anode E xchange C urrent Densit y field . Likewise , you c an sp ecify a v alue f or the e xchange cur rent densit y at the c athode (the default v alue is 100 ) using the Catho de Exchange C urrent Densit y field . You c an also sp ecify Mole F raction Ref erenc e Values (Equa tion 25.115 -Equa tion 25.117 ) for the fuel cell r eactants in the Electrochemistr y tab . By default , the r eference value f or is 0.8 , the r eference value f or is 0.21 , and the r eference value f or is 0.2 . The B utler-V olmer tr ansf er coefficien ts can b e set in the Electrochemistr y tab as w ell.These c oefficien ts are the and from Equa tion 25.112 for b oth the ano de and the c athode r eactions . 2485Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the S olid O xide F uel C ell With U nresolv ed E lectrolyte Model(33.3) Rememb er tha t has ano dic and c athodic v alues a t both the c athode and the ano de. By default , the value of is set t o 0.5 because of the near ly univ ersal assumption tha t ther e is a symmetr ic balanc e between the f orward and back ward reactions . In most c ases , these default v alues will b e sufficien t. If you find y ourself changing the B utler-V olmer tr ansf er coefficien ts, or if y ou ha ve some other r ate- limiting r eaction in y our fuel c ell simula tion, you ma y also w ant to consider changing the e xponen ts for the st oichiometr ic coefficien ts for the fuel c ell r eactants.These e xponen ts can b e sp ecified in the Electrochemistr y tab . By default , the e xponen t values f or , , and are 0.5 . The Enable Temp erature D ependan t I_0 option allo ws the e xchange cur rent densit y to change as a func tion of t emp erature in an e xponen tial fashion (33.4) wher e you c an pr ovide the v alues f or the c onstan ts and . 33.3.7. Setting U p the E lectrode-E lectrolyt e In terfaces You c an apply sp ecific settings f or b oth y our ano de and y our c athode in terfaces as w ell as set t ortuosit y paramet ers using the ANSY S Fluen t SOFC With U nresolv ed E lectrolyt e M odel thr ough the Electrolyt e and Tortuosit y tab in the SOFC M odel dialo g box. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2486Modeling F uel C ellsFigur e 33.35: The E lectrolyt e and Tortuosit y Tab in the SOFC M odel D ialo g Box 1.Set up the ano de elec trode-elec trolyt e interface. a.Enable the Anode In terface option. b.Selec t the sur face tha t represen ts the ano de elec trode in terface with the elec trolyt e from the c orres- ponding Zone(s) list c.Click Apply . 2.In a similar manner , you c an set up the c athode elec trode-elec trolyt e interface. 3.Set up the t ortuosit y par amet ers. a.Selec t the Enable Tortuosit y option. b.Selec t the appr opriate zone fr om the c orresponding Zone(s) list 2487Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the S olid O xide F uel C ell With U nresolv ed E lectrolyte Modelc.As requir ed, assign t ortuosit y values t o an y porous z ones in y our simula tion. In a p orous z one , the mass diffusion c oefficien t is r educ ed as f ollows due t o the p orosity eff ect: (33.5) There typic ally ar e no standar d means of measur ing t ortuosit y as it must b e either measur ed experimen tally or tuned t o ma tch other e xperimen tal da ta.Tortuosit y value ma y typic ally b e in the r ange of 2 to 4, although y ou c an use much higher v alues . d.Click Apply . You c an do this f or as man y zones as y ou need .When y ou ar e finished setting up the ano de in terface, click the OK butt on. 33.3.8. Setting U p the E lectric Field M odel P aramet ers You c an set up the details of the elec tric field mo del using the Electric F ield tab in the SOFC M odel dialo g box. Figur e 33.36: The E lectric F ield Tab in the SOFC M odel D ialo g Box Here, you c an designa te conduc tive regions and sp ecify their c onduc tivit y, assign b oundar ies t o be contact sur faces and sp ecify the c ontact resistanc es, as w ell as sp ecify which sur faces ar e gr ounded and which sur faces e xhibit a cur rent. The Voltage Tap S urface is the sur face tha t is gr ounded (tha t is, ).The Current Tap S urface is the sur face tha t cur rent is b eing dr awn fr om (tha t is, is assigned a v alue). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2488Modeling F uel C ells33.3.9. User-A ccessible F unc tions f or the S olid O xide F uel C ell With U nre- solv ed E lectrolyt e M odel You c an dir ectly inc orporate your o wn f ormula tions and da ta for the pr operties of the solid o xide fuel cell mo del using the constit.c sour ce code file . The f ollowing listing r epresen ts a descr iption of the c ontents of the constit.c sour ce code file: real Nernst (real sp_a[], real sp_c[], real P_a, real P_c, real T_a, real T_c, real *DNDY) Retur ns the N ernst p otential using Equa tion 25.106 . real Activation (real Y[], real P, real T, real i, real i_0, real alpha_a, real alpha_b, int species, real *dA_di) Retur ns the ac tivation o verpotential b y solving Equa tion 25.112 . real Resistivity (real T) Retur ns the elec trolyt e resistanc e (either a c onstan t value , or c omput ed using Equa tion 33.2 (p.2483 )). real Leakage_Current_Density(realT) Retur ns the leak age cur rent densit y sp ecified in the SOFC M odel dialo g box and c an b e overwritten as a func tion of t emp erature. real Solve_Butler_Volmer_NR (real i, real i0, real A, real B, real *detadi); Retur ns the ac tivation o verpotential b y solving Equa tion 25.112 . real CONDUCTIVITY_CELL(cell_t c, Thread *t) Retur ns the c ell c onduc tivit y value used in the Electric Field tab of the SOFC M odel dialo g box.This func tion c an b e overwritten t o look up the c onduc tive zone gr oup ID (1 thr ough 5). A conditional sta temen t allows you t o perform various tasks f or respective conduc tive zones . For non-c onduc tive zones , this func tion r etur ns a v alue of 0. real CONTACT_RESIST_FACE (face_t f, Thread *t) Retur ns the c ontact resistanc e value used in the Electric Field tab of the SOFC M odel dialo g box.This func tion c an b e overwritten t o look up the c ontact resistanc e gr oup ID (1 thr ough 3). A conditional statemen t allo ws you t o perform various tasks f or respective contact resistanc e sur faces. For non-c ontact resistanc e sur faces, this func tion r etur ns a v alue of 0. real h2_co_split_func(cell_t c_an, Thread *t_an) Retur ns the / split fac tor defined in Equa tion 25.133 .This c an b e overwritten as needed t o define your o wn split fac tor. For mor e inf ormation, see Compiling the C ustomiz ed S olid O xide F uel C ell With U nresolv ed E lectrolyt e Source Code (p.2490 ). 33.3.9.1. Compiling the C ustomiz ed S olid O xide F uel C ell With U nresolv ed E lectrolyte Source Code 2489Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the S olid O xide F uel C ell With U nresolv ed E lectrolyte Model33.3.9.1. Compiling the C ustomiz ed S olid O xide F uel C ell With Unr esol ved Elec trolyte Sour ce Code This sec tion includes instr uctions on ho w to compile a cust omiz ed S olid O xide F uel C ell With U nre- solv ed E lectrolyt e user-defined mo dule . Imp ortant It is assumed tha t you ha ve a basic familiar ity with c ompiling user-defined func tions (UDFs). For an in troduc tion on ho w to compile UDFs , refer to the Fluen t Customiza tion M anual . You will first w ant to use a lo cal copy of the sofc directory in the addons directory before you r e- compile the S olid O xide F uel C ell With U nresolv ed E lectrolyt e mo dule . 33.3.9.1.1. Compiling the C ustomiz ed S our ce Code Under Linux 1.Make a lo cal copy of the sofc directory. Do not cr eate a symb olic link. Imp ortant The cust om v ersion of the libr ary must b e named acc ording t o the c onvention used by ANSY S Fluen t: for e xample ,sofc . 2.Change dir ectories t o the sofc/src directory. 3.Make changes t o the constit.c file. 4.Define the FLUENT_ADDONS environmen t variable t o correspond t o your cust omiz ed v ersion of the Solid O xide F uel C ell With U nresolv ed E lectrolyt e mo dule . 5.Change dir ectories t o the sofc/ directory. 6.Issue the f ollowing make command: make FLUENT_INC=[ansys_inc/v195/fluent] FLUENT_ARCH=[arch] -f Makefile-client wher e your_arch is lnx86 on LINUX, or ultra on the Sun op erating sy stem, and so on. The f ollowing e xample demonstr ates the st eps r equir ed t o set up and r un a cust omiz ed v ersion of the F uel C ell and E lectrolysis mo dule tha t is lo cated in a f older c alled home/sample : 1.Make a dir ectory. mkdir -p /home/sample 2.Copy the default addon libr ary to this lo cation. cp -RH [ansys_inc/v195/fluent]/fluent19.5.0/addons/sofc /home/sample/sofc Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2490Modeling F uel C ells3.Using a t ext edit or, mak e the appr opriate changes t o the constit.c file lo cated in /home/sample/sofc/src/constit.c 4.Build the libr ary. cd /home/sample/sofc make FLUENT_INC=[ansys_inc/v195/fluent] FLUENT_ARCH=[arch] -f Makefile-client 5.Set the FLUENT_ADDONS environmen t variable (using CSH, other shells will diff er). setenv FLUENT_ADDONS /home/sample 6.Start ANSY S Fluen t and load the cust omiz ed mo dule using the t ext interface command . 33.3.9.1.2. Compiling the C ustomiz ed S our ce Code Under Windo ws 1.Open Visual S tudio .NET at the DOS pr ompt. 2.Make sur e tha t the FLUENT_INC environmen t variable is c orrectly set t o the cur rent ANSY S Fluen t in- stalla tion dir ectory (for e xample ,ANSYS Inc\v195\fluent ). 3.Make a lo cal copy of the sofc folder . Do not cr eate a shor tcut. 4.Enter the sofc\src folder . 5.Make changes t o the constit.c file. 6.Define the FLUENT_ADDONS environmen t variable t o correspond t o your cust omiz ed v ersion of the Solid O xide F uel C ell With U nresolv ed E lectrolyt e mo dule . 7.Retur n to the sofc folder . 8.Issue the f ollowing c ommand in the c ommand windo w: nmake /f makefile_master-client.nt 2491Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the S olid O xide F uel C ell With U nresolv ed E lectrolyte ModelRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2492Chapt er 34: Modeling M agnet ohydrodynamics The ANSY S Fluen t Magnet ohydrodynamics (MHD) M odule C hapt er tells y ou wha t you need t o know to model magnet ohydrodynamics with ANSY S Fluen t. Additional inf ormation ab out the mo del is pr ovided in the f ollowing sec tions: 34.1. Introduction 34.2. Implemen tation 34.3. Using the ANSY S Fluen t MHD M odule 34.4. Guidelines F or U sing the ANSY S Fluen t MHD M odel 34.5. Definitions of the M agnetic F ield 34.6. External M agnetic F ield D ata Format 34.1. Introduc tion Magnet ohydrodynamics r efers t o the in teraction b etween an applied elec tromagnetic field and a flowing , elec trically-c onduc tive fluid .The ANSY S Fluen t MHD mo del enables y ou t o analyz e the b ehavior of elec trically c onduc ting fluid flo w under the influenc e of c onstan t (DC) or oscilla ting (A C) elec tromag- netic fields .The e xternally-imp osed magnetic field ma y be gener ated either b y selec ting simple built- in func tions or b y imp orting a user-supplied da ta file . For multiphase flo ws, the MHD mo del is c ompa tible with b oth the discr ete phase mo del (DPM), the v olume-of-fluid ( VOF) and E uler ian M ultiphase in ANSY S Fluen t, including the eff ects of a discr ete phase on the elec trical conduc tivit y of the mix ture. This chapt er descr ibes the ANSY S Fluen t MHD mo del. Modeling M agnet ohydrodynamics provides the- oretical back ground inf ormation. Implemen tation (p.2493 ) summar izes the UDF-based sof tware imple- men tation. Instr uctions f or getting star ted with the mo del ar e pr ovided in Using the ANSY S Fluen t MHD Module (p.2495 ).Guidelines F or U sing the ANSY S Fluen t MHD M odel (p.2509 ) provides a c ondensed overview on ho w to use the MHD mo del, while Definitions of the M agnetic F ield (p.2512 ) contains definitions f or the magnetic field ,External M agnetic F ield D ata Format (p.2513 ) descr ibes the e xternal magnetic field da ta format, and Magnet ohydrodynamics Text Commands lists the t ext commands in the MHD mo del. 34.2. Implemen tation The MHD mo del is implemen ted using user-defined func tions (UDF) as an ANSY S Fluen t add-on mo dule , which is loaded in to ANSY S Fluen t at run time .The mo del is acc essed thr ough a numb er of UDF schemes . The magnetic induc tion equa tion giv en b y Equa tion 26.14 or Equa tion 26.16 and the elec tric potential equa tion giv en b y Equa tion 26.22 are solv ed thr ough user-defined sc alar (UDS) tr ansp ort equa tions . Other mo del-r elated v ariables such as the e xternal magnetic field da ta, cur rent densit y, Lorentz force and J oule hea t are stored as user-defined memor y (UDM) v ariables .The MHD mo del setup and par amet ers are en tered using the MHD M odel graphic al user in terface (GUI) dialo g box and a set of t ext user in terface (TUI) c ommands descr ibed in Using the ANSY S Fluen t MHD M odule (p.2495 ). Detailed inf ormation c an be found in the f ollowing sec tions: 34.2.1. Solving M agnetic Induc tion and E lectric Potential E qua tions 34.2.2. Calcula tion of MHD Variables 34.2.3. MHD In teraction with F luid F lows 2493Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.34.2.4. MHD In teraction with D iscrete Phase M odel 34.2.5. Gener al User-D efined F unctions 34.2.1. Solving M agnetic Induc tion and E lectric Potential E qua tions The magnetic induc tion equa tion and the elec tric potential equa tions ar e solv ed thr ough user-defined scalar tr ansp ort equa tions . For the magnetic induc tion equa tion a set of 2 or 3 sc alar equa tions ar e solv ed, each r epresen ting a C artesian c omp onen t of the induc ed magnetic field v ector in a 2D or 3D case. For the elec tric potential equa tion a single sc alar equa tion is solv ed. The c onvection and the diffusion t erms of the sc alar equa tions ar e defined using user func tions DEFINE_UDS_FLUX(mhd_flux, ..., ns) and DEFINE_DIFFUSIVITY (mhd_ magnet- ic_diffusivity, ..., ns) respectively.The user-defined sc alar equa tion is iden tified b y the scalar inde x ns. The sour ce terms t o the induc tion equa tions and the p otential equa tion ar e implemen ted using user func tion DEFINE_SOURCE(mhd_mag_source, ..., eqn) and DEFINE_SOURCE (mhd_phi_source, ..., eqn) respectively, wher e eqn iden tifies the sc alar equa tions . For tr ansien t cases , the additional unst eady sour ce term is in troduced thr ough the user func tion DEFINE_UDS_UNSTEADY(mhd_unsteady_source, ..., ns) , wher e ns iden tifies the sc alar being solv ed. The induc tion and p otential equa tions c an also b e solv ed in solid z ones , in which c ase the fluid v elocity terms in the equa tions ar e not c onsider ed. For multiphase flo ws, the MHD equa tions ar e solv ed in the mixture domain only . The w all b oundar y conditions ar e implemen ted thr ough user pr ofile func tions (DEFINE_PRO- FILE(mhd_bc_... ), and ar e applied t o the C artesian c omp onen ts of the induc ed magnetic field vector or t o the elec tric potential. For e xternal w all b oundar ies, three t ypes of b oundar y conditions (elec trically insula ting , conduc ting , and "thin w all"), can b e applied .The ’thin w all’ type boundar y refers to an e xternal w all wher e a 1D magnetic or elec tric potential diffusion nor mal t o the b oundar y is as- sumed , and the w all ma terial and the thick ness ar e sp ecified f or the b oundar y. For in ternal w all boundar ies, tha t is the b oundar ies b etween fluid/solid or solid/solid z ones , a coupled b oundar y condition is applied . 34.2.2. Calcula tion of MHD Variables Apart from the C artesian c omp onen ts of the magnetic field v ectors and the elec tric potential func tion, which ar e stored as user-defined sc alars , other MHD-r elated v ariables include the induc ed elec tric current densit y vector, induc ed elec tric field v ector, the L orentz force vector and J oule hea t.These variables ar e stored in user-defined memor y locations . Updating of MHD v ariables is acc essed thr ough the user func tion DEFINE_ADJUST(mhd_adjust,...) .The v ariables ar e up dated a t the star t of each it eration using the solv ed induc ed magnetic field fr om the pr evious it eration. 34.2.3. MHD In teraction with F luid F lows Additional sour ce terms due t o the magnetic induc tion ar e added t o the flo w momen tum and ener gy equa tions as user defined sour ce terms. For the momen tum equa tion, user func tion DEFINE_SOURCE(mhd_mom_source, ..., eqn) is used t o in troduce the L orentz force to the equa tion, wher e eqn iden tifies the C artesian c omp onen t of the fluid momen tum. For the ener gy Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2494Modeling M agnet ohydrodynamicsequa tion, the additional sour ce due t o Joule hea ting is added thr ough user func tion DEFINE_SOURCE(mhd_energy_source,..., eqn) , wher e eqn is the ener gy equa tion inde x. 34.2.4. MHD In teraction with D iscr ete Phase M odel In discr ete phase mo deling , the L orentz force ac ting on char ged par ticles is in troduced thr ough the user func tion DEFINE_DPM_BODY_FORCE(mhd_dpm_force, ...) . User func tion DEFINE_DPM_SOURCE(mhd_dpm_source, ...) is used t o up date the v olume fr action of the discr ete phase inside a fluid c ell and the v olume-w eigh ted elec tric conduc tivit y of the discr ete phase . 34.2.5. Gener al U ser-D efined F unc tions Several gener al UDFs ar e used as par t of the MHD mo del implemen tation. •DEFINE_INIT(mhd_init,...) is an initializa tion func tion c alled dur ing the gener al case initializa tion to set up the e xternal magnetic field and initializ e MHD mo del par amet ers and v ariables . •DEFINE_ADJUST(mhd_adjust,...) is called a t the star t of each it eration. It is used t o adjust the magnetic b oundar y conditions and up date MHD r elated v ariables and pr operties. 34.3. Using the ANSY S Fluen t MHD M odule This chapt er pr ovides basic instr uctions t o install the magnet ohydrodynamics (MHD) mo dule and solv e MHD pr oblems in ANSY S Fluen t. It assumes tha t you ar e alr eady familiar with standar d ANSY S Fluen t features, including the user-defined func tion pr ocedur es descr ibed in the Fluen t Customiza tion M anual . Guidelines F or U sing the ANSY S Fluen t MHD M odel (p.2509 ) also outlines the gener al pr ocedur e for using the MHD mo del. This chapt er descr ibes the f ollowing: 34.3.1. MHD M odule Installa tion 34.3.2. Loading the MHD M odule 34.3.3. MHD M odel S etup 34.3.4. MHD S olution and P ostpr ocessing 34.3.5. Limita tions 34.3.1. MHD M odule Installa tion The MHD mo dule is pr ovided as an add-on mo dule with the standar d ANSY S Fluen t licensed sof tware. The mo dule is installed in a dir ectory called addons/mhd in y our installa tion ar ea.The MHD mo dule consists of a UDF libr ary and a pr e-compiled Scheme libr ary, which must b e loaded and ac tivated b efore calcula tions c an b e performed . 34.3.2. Loading the MHD M odule The MHD mo dule is loaded in to ANSY S Fluen t thr ough the t ext user in terface (TUI). The mo dule c an only b e loaded when a v alid ANSY S Fluen t case file has b een set or r ead.The t ext command t o load the mo dule is define → models → addon-module . A list of ANSY S Fluen t add-on mo dules is displa yed: > /define/models/addon-module Fluent Addon Modules: 2495Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the ANSY S Fluen t MHD M odule 0. None 1. MHD Model 2. Fiber Model 3. Fuel Cell and Electrolysis Model 4. SOFC Model with Unresolved Electrolyte 5. Population Balance Model 6. Adjoint Solver 7. Battery Module 8. MSMD Battery Model 9. PEM Fuel Cell Model Enter Module Number: [0] 1 Selec t the MHD mo del b y en tering the mo dule numb er 1. During the loading pr ocess a Scheme libr ary containing the gr aphic al and t ext user in terface, and a UDF libr ary containing a set of user defined func tions ar e loaded in to ANSY S Fluen t. A message Addon M odule: mhd ...loaded! is displa yed a t the end of the loading pr ocess. The basic set up of the MHD mo del is p erformed aut oma tically when the MHD mo dule is loaded suc- cessfully .The set up includes: •Selec ting the default MHD metho d •Allocating the r equir ed numb er of user-defined sc alars and memor y locations naming of : –User-defined sc alars and memor y locations –All UDF H ooks f or MHD initializa tion and adjustmen t –MHD equa tion flux and unst eady terms –Source terms f or the MHD equa tions –Additional sour ce terms f or the fluid momen tum and ener gy equa tions –Default MHD b oundar y conditions f or e xternal and in ternal b oundar ies –A default set of mo del par amet ers •DPM r elated func tions ar e also set , if the DPM option has b een selec ted in the ANSY S Fluen t case set up . The MHD mo dule set up is sa ved with the ANSY S Fluen t case file .The mo dule is loaded aut oma tically when the c ase file is subsequen tly r ead in to ANSY S Fluen t. Note tha t in the sa ved c ase file , the MHD module is sa ved with the absolut e pa th.Therefore, if the lo cations of the MHD mo dule installa tion or the sa ved c ase file ar e changed , ANSY S Fluen t will not b e able t o load the mo dule when the c ase file is subsequen tly r ead. To unload the pr eviously sa ved MHD mo dule libr ary, open the UDF Libr ary M anager dialo g box Paramet ers & C ustomiza tion → User D efined F unc tions Manage ... and r eload the mo dule as descr ibed ab ove. Note tha t the pr eviously sa ved MHD mo del setup and paramet ers ar e pr eser ved. 34.3.3. MHD M odel S etup Following the loading of the MHD mo dule , you c an acc ess the MHD M odel dialo g box using Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2496Modeling M agnet ohydrodynamicsSetup → Models → MHD M odel Edit... or using the t ext command define → models → mhd-model Both the MHD M odel dialo g box and TUI c ommands ar e designed f or the f ollowing tasks: •Enable/disable the MHD mo del. •Selec t the MHD metho d. •Apply an e xternal magnetic field . •Set b oundar y conditions . •Set solution c ontrol par amet ers. Operations of these tasks thr ough the MHD M odel dialo g box are descr ibed in the f ollowing sec tions . The set of MHD t ext commands ar e list ed in Magnet ohydrodynamics Text Commands . For mor e inf ormation, see the f ollowing sec tions: 34.3.3.1. Enabling the MHD M odel 34.3.3.2. Selec ting an MHD M etho d 34.3.3.3. Applying an Ex ternal M agnetic F ield 34.3.3.4. Setting U p Boundar y Conditions 34.3.3.5. Solution C ontrols 34.3.3.1. Enabling the MHD Mo del If the MHD mo del is not enabled af ter the MHD mo dule is loaded f or the first time , you c an enable it by selec ting Enable MHD in the MHD M odel dialo g box, sho wn in Figur e 34.1: Enabling the MHD Model D ialog Box (p.2497 ).The dialo g box expands t o its full siz e when the mo del is enabled , as sho wn in Figur e 34.2: The MHD M odel D ialog Box (p.2498 ). Figur e 34.1: Enabling the MHD M odel D ialo g Box 2497Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the ANSY S Fluen t MHD M oduleFigur e 34.2: The MHD M odel D ialo g Box 34.3.3.2. Selec ting an MHD Metho d The metho d used f or MHD c alcula tion c an b e selec ted under MHD M etho d in the MHD M odel dialo g box.The t wo metho ds,Magnetic Induc tion and Electrical P otential, are descr ibed in Magnetic In- duc tion M etho d and Electric Potential M etho d, For the M agnetic Induc tion metho d, 2 or 3 user-defined sc alars ar e allo cated f or the solution of the induc ed magnetic field in 2D or 3D c ases .The sc alars ar e list ed as B_x, B_y and B_z r epresen ting the Cartesian c omp onen ts of the induc ed magnetic field v ector.The unit f or the sc alar is Tesla. For the E lectrical Potential metho d, 1 user-defined sc alar is solv ed f or the elec tric potential field .The scalar is list ed as and has the unit of Volt. Table 34.1: User-D efined Sc alars in MHD M odel (p.2498 ) lists the user-defined sc alars used b y the t wo metho ds. Table 34.1: User-D efined Sc alars in MHD M odel Descr iption Unit Name Scalar Metho d X comp onen t of induc ed magnetic field ( ) Tesla B_x Scalar-0 Induc tion Y comp onen t of induc ed magnetic field ( )Tesla B_y Scalar-1 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2498Modeling M agnet ohydrodynamicsDescr iption Unit Name Scalar Metho d Z comp onen t of induc ed magnetic field ( ) Tesla B_z Scalar-2 (3-D) Electric potential ( ) Volt Phi Scalar-0 Potential 34.3.3.3. Appl ying an E xternal M agnetic F ield Applic ation of an e xternal magnetic field t o the c omputa tion domain is done under the External Field B0 tab in the MHD M odel dialo g box, as sho wn in Figur e 34.3: The MHD M odel D ialog Box for Patching an Ex ternal M agnetic F ield (p.2499 ).Two B0 Input Option s are available f or setting up the external magnetic field . One option is t o Patch the c omputa tional domain with a c onstan t (DC F ield ) and/or v arying ( AC Field ) type.The other option is t o Imp ort the field da ta fr om a magnetic da ta file tha t you pr ovide . With the Patch option enabled , the A C field c an b e expressed as a func tion of time (sp ecified b y Frequenc y), and spac e (sp ecified b y wavelength, propaga tion dir ection and initial phase off set). The spac e comp onen ts ar e set under the B0 C omp onen t, as in Figur e 34.3: The MHD M odel D ialog Box for P atching an Ex ternal M agnetic F ield (p.2499 ). Figur e 34.3: The MHD M odel D ialo g Box for P atching an E xternal M agnetic F ield You c an also sp ecify a Moving F ield with a w ave form tha t is either a sinusoidal or a squar e wave func tion ( Figur e 34.4: The MHD M odel D ialog Box for S pecifying a M oving F ield (p.2500 )). Definitions 2499Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the ANSY S Fluen t MHD M odulefor the sinusoidal and squar e wave forms of pa tched magnetic fields ar e pr ovided in Definitions of the M agnetic F ield (p.2512 ). Figur e 34.4: The MHD M odel D ialo g Box for S pecifying a M oving F ield Selec ting Imp ort under the B0 Input Option in the MHD M odel dialo g box, as seen in Figur e 34.5: The MHD M odel D ialog Box for Imp orting an Ex ternal M agnetic F ield (p.2501 ), will r esult in the imp ort of magnetic field da ta.The da ta filename c an b e en tered in the B0 D ata F ile N ame field , or selec ted from y our c omput er file sy stem using the Browse... butt on. Magnetic da ta can also b e gener ated using a thir d-par ty pr ogram such as MA GNA. The r equir ed f ormat of the magnetic field da ta file is given in External M agnetic F ield D ata Format (p.2513 ). When using the Imp ort option, the B0 D ata M edia is either set t o Non-C onduc ting or Conduc ting , dep ending on the assumptions used in gener ating the magnetic field da ta. (These choic es c orrespond to “Case 1” and “Case 2” , respectively, as discussed in Magnetic Induc tion M etho d.) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2500Modeling M agnet ohydrodynamicsFigur e 34.5: The MHD M odel D ialo g Box for Imp orting an E xternal M agnetic F ield The Field Type is det ermined b y the field da ta fr om the da ta file .The choic e of either the DC F ield or the AC Field option in the dialo g box is ir relevant if the imp ort da ta is either DC or A C. However, selec tion of b oth options indic ates tha t da ta of b oth field t ypes ar e to be imp orted fr om the da ta file, and sup erimp osed t ogether t o pr ovide the final e xternal field da ta. Make sur e tha t the da ta file contains t wo sec tions f or the r equir ed da ta. See External M agnetic F ield D ata Format (p.2513 ) for details on da ta file with t wo da ta sec tions . The Apply E xternal F ield ... butt on op ens the Apply E xternal B0 F ield dialo g box as sho wn in Fig- ure 34.6: Apply Ex ternal B0 F ield D ialog Box (p.2502 ).To apply the e xternal field da ta to zones or r egions in the c omputa tional domain, selec t the z one names or r egist er names of mar ked r egions fr om the dialo g box and click the Apply butt on. The Reset E xternal F ield butt on sets the e xternal magnetic field v ariable t o zero. 2501Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the ANSY S Fluen t MHD M oduleFigur e 34.6: Apply E xternal B0 F ield D ialo g Box 34.3.3.4. Setting Up B oundar y Conditions Boundar y conditions r elated t o MHD c alcula tions ar e set under the Boundar y Condition tab in the MHD M odel dialo g box. Boundar y conditions c an b e set t o cell z ones and w all b oundar ies. For c ell z ones , only the asso ciated ma terial c an b e changed and its pr operties mo dified .Figur e 34.7: Cell Boundar y Condition S etup (p.2503 ) sho ws the dialo g box for c ell z one b oundar y condition setup .The cell z one ma terial c an b e selec ted fr om the Material N ame drop-do wn list. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2502Modeling M agnet ohydrodynamicsFigur e 34.7: Cell B oundar y Condition S etup Note tha t the ma terials a vailable in the list ar e set in the gener al ANSY S Fluen t case set up . Refer to the ANSY S Fluen t User G uide f or details on adding ma terials t o an ANSY S Fluen t case.The pr operties of the selec ted ma terial c an b e mo dified in the Boundar y Condition tab b y click ing Edit... to the right of the ma terial name .This op ens the Edit M aterial dialo g box, as sho wn in Figur e 34.8: Editing Material P roperties within B oundar y Condition S etup (p.2504 ).The ma terial pr operties tha t ma y be modified include the elec trical conduc tivit y and magnetic p ermeabilit y.The ma terial elec trical con- duc tivit y can b e set as c onstan t, a func tion of t emp erature in f orms of piec ewise-linear , piec ewise- polynomial or p olynomial, or as a user-defined func tion. The ma terial magnetic p ermeabilit y can only be set as a c onstan t. 2503Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the ANSY S Fluen t MHD M oduleFigur e 34.8: Editing M aterial P roperties within B oundar y Condition S etup For w all b oundar ies, the b oundar y condition c an b e set as an Insula ting Wall,Conduc ting Wall, Coupled Wall or Thin Wall.The dialo g box for w all b oundar y condition set up is sho wn in Fig- ure 34.9: Wall B oundar y Condition S etup (p.2505 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2504Modeling M agnet ohydrodynamicsFigur e 34.9: Wall B oundar y Condition S etup •The insula ting w all is used f or b oundar ies wher e ther e is no elec tric cur rent going thr ough the b oundar y. •The c onduc ting w all is used f or b oundar ies tha t are perfect conduc tors. •The c oupled w all should b e used f or w all b oundar ies b etween solid/solid or solid/fluid z ones wher e the MHD equa tions ar e solv ed. •The thin w all type boundar y can b e used f or e xternal w all tha t has a finit e elec trical conduc tivit y. For c onduc ting w alls and thin w all b oundar ies, the w all ma terial c an b e selec ted fr om the Material Name drop-do wn list , and its pr operties mo dified thr ough the Edit M aterial dialo g box. A w all thick ness must b e sp ecified f or thin w all t ype boundar ies. If the Electric P otential metho d is selec ted, the c onduc ting w all b oundar y is sp ecified b y either of Voltage or Current Densit y at the b oundar y, as sho wn in Figur e 34.10: Conduc ting Wall B oundar y Conditions in E lectrical Potential M etho d (p.2506 ). 2505Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the ANSY S Fluen t MHD M oduleFigur e 34.10: Conduc ting Wall B oundar y Conditions in E lectrical P otential M etho d 34.3.3.5. Solution C ontr ols Under the Solution C ontrol tab in the MHD M odel dialo g box,Figur e 34.11: Solution C ontrol Tab in the MHD M odel D ialog Box (p.2507 ), a numb er of par amet ers c an b e set tha t control the solution process in an MHD c alcula tion. The MHD mo del c an b e initializ ed using the Initializ e MHD butt on. When the DPM mo del is enabled in the ANSY S Fluen t case set up , the r elated v ariables used in the MHD mo del c an b e initializ ed using the Initializ e DPM butt on. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2506Modeling M agnet ohydrodynamicsFigur e 34.11: Solution C ontrol Tab in the MHD M odel D ialo g Box You ha ve the option t o enable or disable the Solve MHD E qua tion .When the Solve MHD E qua tion is enabled , you ha ve the choic e to Include L orentz F orce and/or Include J oule H eating in the solution of flo w momen tum and ener gy equa tions .The under-r elaxa tion fac tor for the MHD equa tions can also b e set. The str ength of the imp osed e xternal magnetic field c an b e adjust ed b y sp ecifying and applying sc ale factors t o the e xternal DC and/or A C magnetic field da ta. 34.3.4. MHD S olution and P ostpr ocessing The f ollowing sec tions descr ibe the solution and p ostpr ocessing st eps f or the MHD mo del: 34.3.4.1. MHD M odel Initializa tion 34.3.4.2. Iteration 34.3.4.3. Postpr ocessing 34.3.4.1. MHD Mo del Initialization Initializa tion of the MHD mo del in volves setting the e xternally-imp osed magnetic field and initializing all MHD r elated user-defined sc alars and memor y variables . 2507Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the ANSY S Fluen t MHD M oduleWhen an ANSY S Fluen t case is initializ ed, all user-defined sc alar and memor y variables ar e set t o zero. The e xternal magnetic field da ta is set fr om the External F ield B0 tab in the MHD M odel dialo g box. The Initializ e MHD butt on under the Solution C ontrol tab c an b e used t o initializ e the mo del dur ing an ANSY S Fluen t solution pr ocess. It is used when MHD eff ects ar e added t o a fully or par tially solv ed flow field , or when the mo del par amet ers ar e changed dur ing an MHD c alcula tion. It only clears the scalar v ariables and most of the memor y locations used in the MHD mo del, the memor y variables f or the e xternal magnetic field da ta ar e pr eser ved. 34.3.4.2. Iteration It is of ten an eff ective str ategy to begin y our MHD c alcula tions using a pr eviously-c onverged flo w field solution. With this appr oach, the induc tion equa tions themselv es ar e gener ally easy t o converge. The under-r elaxa tion fac tors f or these equa tions c an b e set t o 0.8 0.9, although f or v ery str ong magnetic fields , smaller v alues ma y be needed . For the elec tric potential equa tion, the c onvergenc e is gener ally slo w. However, the under-r elaxa tion v alue f or this equa tion should not b e set t o 1. As additional sour ce terms ar e added t o the momen tum and ener gy equa tions , the under-r elaxa tion factors f or these equa tions should gener ally b e reduc ed t o impr ove the r ate of c onvergenc e. In c ase of c onvergenc e difficulties , another helpful str ategy is t o use the B0 Sc ale F actor in the Solution Control tab ( Figur e 34.2: The MHD M odel D ialog Box (p.2498 )).This will gr adually incr ease the MHD effect to its ac tual magnitude thr ough a ser ies of r estar ts.When the str ength of the e xternally imp osed magnetic field is str ong , it is ad visable t o star t the c alcula tion with a r educ ed str ength e xternal field by applying a small sc ale fac tor.When the c alcula tion is appr oaching c onvergenc e the sc ale fac tor can b e incr eased gr adually un til the r equir ed e xternal field str ength is r eached . 34.3.4.3. Postpr ocessing You c an use the standar d postpr ocessing facilities of ANSY S Fluen t to displa y the MHD c alcula tion results . Contours of MHD v ariables c an b e displa yed using Results → Graphics → Contours Edit... The MHD v ariables c an b e selec ted fr om the v ariable list. Vectors of MHD v ariables , such as the magnetic field v ector and cur rent densit y vector, can b e displa yed using Results → Graphics → Vectors Edit... The v ector fields of the MHD v ariables ar e list ed in the Vectors of drop-do wn list in the Vectors dialo g box.Table 34.2: MHD Vectors (p.2508 ) lists the MHD r elated v ector fields . Table 34.2: MHD Vectors Descr iption Unit Name Induc ed magnetic field v ector TeslaInduc ed- -Field Applied e xternal magnetic field v ector TeslaExternal- -Field Induc ed cur rent densit y field v ector Current-Densit y Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2508Modeling M agnet ohydrodynamicsDescr iption Unit Name Electric field densit y vector V/mElectric-Field Lorentz force vector Lorentz-Force Note •For field v ariables tha t are stored in UDM, use the c orresponding v ariables f or p ost pr o- cessing . Post pr ocessing the UDM itself is not r ecommended . •For reviewing simula tion r esults in CFD P ost f or cases in volving UDM or UDS, export the solution da ta as CFD-P ost-c ompa tible file (.cdat ) in F luen t and then load this file in to CFD-P ost. 34.3.5. Limita tions Many MHD applic ations in volve the simultaneous use of other ad vanced ANSY S Fluen t capabilities such as solidific ation, free sur face mo deling with the v olume of fluid ( VOF) appr oach, DPM, Euler ian multiphase , and so on. You should c onsult the la test ANSY S Fluen t do cumen tation f or the limita tions that apply t o those f eatures. In addition, you should b e aware of the f ollowing limita tions of the MHD capabilit y. •As explained in Modeling M agnet ohydrodynamics , the MHD mo dule assumes a sufficien tly c onduc tive fluid so tha t the char ge densit y and displac emen t cur rent terms in M axwell’s equa tions c an b e neglec ted. For mar ginally c onduc tive fluids , this assumption ma y not b e valid. More inf ormation ab out this simplific- ation is a vailable in the biblio graph y. •For elec tromagnetic ma terial pr operties, only c onstan t isotr opic mo dels ar e available . Multiphase v olume fractions ar e not dep enden t on t emp erature, species c oncentration, or field str ength. However, sufficien tly strong magnetic fields c an c ause the c onstan t-permeabilit y assumption t o become in valid. •You must sp ecify the applied magnetic field dir ectly.The alt ernative sp ecific ation of an imp osed elec trical current is not supp orted. •In the c ase of alt ernating-cur rent (AC) magnetic fields , the c apabilit y has b een designed f or relatively lo w frequencies; explicit t emp oral resolution of each c ycle is r equir ed. Although not a fundamen tal limita tion, the c omputa tional e xpense of simula ting high-fr equenc y eff ects ma y become e xcessiv e due t o small r equir ed time st ep siz e.Time-a veraging metho ds to inc orporate high-fr equenc y MHD eff ects ha ve not b een imple- men ted. 34.4. Guidelines F or U sing the ANSY S Fluen t MHD M odel This sec tion pr ovides a basic outline f or installing the magnet ohydrodynamics (MHD) mo dule and solving MHD pr oblems in ANSY S Fluen t. 34.4.1. Installing the MHD M odule 2509Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Guidelines F or U sing the ANSY S Fluen t MHD M odel34.4.2. An Overview of U sing the MHD M odule Imp ortant While Using the ANSY S Fluen t MHD M odule (p.2495 ) covers much of the same ma terial in greater detail, this sec tion pr esen ts a set of guidelines f or solving t ypic al MHD pr oblems with ANSY S Fluen t, with o ccasional r eferences to Using the ANSY S Fluen t MHD M odule (p.2495 ) wher e mor e inf ormation c an b e found . 34.4.1. Installing the MHD M odule Before using the MHD mo dule , you first need t o install the nec essar y files on to your c omput er.These files ar e pr ovided with y our standar d installa tion of ANSY S Fluen t.They can b e found in y our installa tion area in a dir ectory called addons/mhd .The MHD mo dule is loaded in to ANSY S Fluen t thr ough the text user in terface (TUI) define → models → addon-module only af ter a v alid ANSY S Fluen t case file has b een set or r ead. Onc e the MHD mo del is installed , benea th the mhd directory ther e ar e two sub directories: a lib dir- ectory, and a dir ectory corresponding t o your sp ecific ar chitecture,ntx86 for e xample .The lib dir- ectory holds a Scheme c ode c alled addon.bin tha t contains the MHD mo dule gr aphic al in terface. The sp ecific ar chitecture dir ectory,ntx86 for e xample , contains the f ollowing sub directories tha t hold various ANSY S Fluen t files: 2d 2ddp 3d 3ddp 2d_host 2ddp_host 3d_host 3ddp_host 2d_node 2ddp_node 3d_node 3ddp_node 34.4.2. An Overview of U sing the MHD M odule To use the MHD mo dule in an ANSY S Fluen t simula tion, follow the gener al guidelines: 1.Start ANSY S Fluen t. To begin mo deling y our MHD simula tion, you need t o star t an appr opriate ANSY S Fluen t session. Choose fr om either the 2D,3D,Double P recision , or the par allel v ersion of ANSY S Fluen t. 2.Read in a mesh file or a c ase file . You c an ha ve ANSY S Fluen t read in y our mesh file , a pr eviously sa ved non-MHD c ase file , or a previously sa ved MHD c ase file . Imp ortant Note tha t if y ou r ead in a new mesh file , you need t o perform the appr opriate mesh check and mesh sc ale pr ocedur es. 3.Load the MHD mo dule . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2510Modeling M agnet ohydrodynamicsThe MHD mo dule is loaded in to ANSY S Fluen t using the t ext command define → models → addon-module and en tering the c orresponding mo dule numb er (Loading the MHD M odule (p.2495 )). 4.Set up the MHD mo del. The MHD M odel dialo g box is acc essed using the gr aphic al user in terface (GUI): Setup → Models → MHD M odel Edit... If the MHD mo del is not enabled af ter the MHD mo dule is loaded f or the first time , you c an enable it by click ing the Enable MHD butt on, which will displa y the e xpanded dialo g box (Enabling the MHD M odel (p.2497 )). 5.Selec t an MHD metho d. The metho d used f or the MHD c alcula tion c an b e selec ted under MHD M etho d.The t wo metho ds are •Magnetic Induc tion (Magnetic Induc tion M etho d) •Electrical P otential (Electric Potential M etho d) 6.Apply an e xternal magnetic field . This is done b y en tering v alues f or the B0 c omp onen ts in the External F ield B0 tab . B0 input options can either b e •Patched, or •Imp orted The Field Type will either b e the DC F ield or the AC Field .The Field Type is det ermined b y the field da ta fr om the da ta file . Refer to Applying an Ex ternal M agnetic F ield (p.2499 ) for details on applying an e xternal magnetic field . 7.Set up the b oundar y conditions . Under the Boundar y Condition tab , cell z ones and w all b oundar ies c an b e selec ted as w ell as the corresponding z one t ype. Cell z one ma terials ar e selec ted fr om the Material N ame drop-do wn list. The pr operties of the se- lected ma terial c an b e mo dified b y click ing on the Edit... butt on t o the r ight of the ma terial name . Note tha t the ma terials a vailable in the list ar e set in the gener al ANSY S Fluen t case setup . Setup → Materials The ma terial pr operties tha t ma y be mo dified include the elec trical conduc tivit y and magnetic permeabilit y. Wall b oundar y conditions c an b e set as an Insula ting Wall,Conduc ting Wall,Coupled Wall or Thin Wall (see Setting U p Boundar y Conditions (p.2502 )). 2511Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Guidelines F or U sing the ANSY S Fluen t MHD M odel8.Set solution c ontrols. Under the Solution C ontrol tab: •The MHD equa tion is enabled or disabled . •Lorentz force and J oule hea t sour ces ar e enabled or disabled . •under-r elaxa tion fac tors ar e set (r easonable under-r elaxa tion fac tors f or the MHD equa tions ar e 0.8 0.9). •Scale fac tors c an b e used t o adjust the str ength of the imp osed e xternal magnetic field . As the c alcula tion appr oaches c onvergenc e, the sc ale fac tor in the Solution C ontrol tab c an b e incr eased gr adually un til the r equir ed e xternal field str ength is r eached ( Solution C ontrols (p.2506 )). •The MHD mo del is initializ ed ( MHD M odel Initializa tion (p.2507 )). 9.Run the ANSY S Fluen t MHD simula tion. Solution → Run C alcula tion Set the numb er of it erations . It is of ten an eff ective str ategy to begin y our MHD c alcula tions using a pr eviously-c onverged flo w field solution. With this appr oach, the induc tion equa tions themselv es are gener ally easy t o converge. For mor e inf ormation, see Iteration (p.2508 ). 10.Process the solution da ta. You c an use the standar d postpr ocessing facilities of ANSY S Fluen t to displa y the r esults of an MHD calcula tion. Contours of MHD v ariables c an b e displa yed. Results → Graphics → Contours Edit... The MHD v ariables c an b e selec ted fr om the v ariable list. Vectors of MHD v ariables , such as the magnetic field v ector and cur rent densit y vector, can b e displa yed using cust om v ectors. Results → Graphics → Vectors Edit... For mor e inf ormation, see Postpr ocessing (p.2508 ). 34.5. Definitions of the M agnetic F ield The sinusoidal f orm of the magnetic field is defined as: (34.1) wher e is the mean v ector, is the amplitude v ector, is defined as the pr opaga tion v ector, is the p osition v ector of an arbitr ary point. , and are the , and direction c osines respectively.The quan tities , , and are the fr equenc y, wavelength, and phase off set, respectively. For a non-mo ving field , the pr opaga tion v ector is z ero. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2512Modeling M agnet ohydrodynamicsThe squar e form of the magnetic field is defined as: (34.2) The definition of the pr opaga tion v ector is the same as f or the sinusoidal f orm. 34.6. External M agnetic F ield D ata F ormat The e xternal magnetic field da ta file is in t ext format and of the f ollowing str ucture: ... The first line is an iden tification tag f or the da ta file .The sec ond line defines the numb er of da ta p oints in the , and directions .The ne xt thr ee lines define the r anges in , and directions .The da ta points ar e assumed t o be evenly distr ibut ed along each dir ection. Line 6 defines the A C field flag and frequenc y.When nAC = 0 , the magnetic field is sta tic. For A C field ,nAC = 1 and Freq is the fr equenc y in Hz. The r est of the da ta file c ontains the magnetic field da ta p oints. Each line defines the c omp onen ts of the r eal and imaginar y par ts of the magnetic field v ector on one da ta p oint.The da ta p oints ar e inde xed as: (34.3) The da ta is list ed in the asc ending or der fr om 1 t o , wher e is the t otal numb er of da ta p oints giv en by = . For magnetic fields c omp osed of b oth DC and A C fields , the en tire file str ucture descr ibed ab ove is r e- peated f or the DC and A C par ts.These t wo sec tions within the same file will b e imp orted in to ANSY S Fluen t and st ored separ ately.The or der of the DC and A C sec tions of the file is not imp ortant. The imp orted da ta is in terpreted as a snapshot of the applied magnetic field a t an instan t in time . Comple x form is used t o acc ommo date oscilla ting/mo ving fields .Thus, using c omple x numb ers, and with r eference to the quan tities defined in Definitions of the M agnetic F ield (p.2512 ), (34.4) 2513Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.External M agnetic F ield D ata FormatFor a DC field , (34.5) For an A C field , (34.6) and (34.7) Note tha t when the e xternal magnetic field imp ort option is used , the fr equenc y, , read fr om this file supersedes the v alue sp ecified in the GUI. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2514Modeling M agnet ohydrodynamicsChapt er 35: Modeling C ontinuous F ibers The c ontinuous fib er mo del is pr ovided as an add-on mo dule with the standar d ANSY S Fluen t licensed software. Several fib er spinning t echniques e xist in industr ial fib er pr oduc tion. The most c ommon t ypes ar e melt spinning and dr y spinning . In melt spinning , the p olymer is hea ted ab ove its melting p oint and e xtruded in a liquid sta te thr ough nozzles in to a v ertical spinning chamb er.The molt en p olymer is pr ocessed in an iner t gas en vironmen t, such as nitr ogen, then e xtruded a t high pr essur e and a c onstan t rate in to a c ooler air str eam, thus so- lidifying the fib er filamen ts. In dr y spinning , the liquefac tion of the p olymer is obtained b y dissolving it in a suitable solv ent.This technique of ten is applied t o polymers tha t are destr oyed ther mally b efore reaching its melting p oint or if the pr oduc tion pr ocess leads t o a solv ent/polymer mix ture. In the spinning chamb er, the solv ent vaporizes b y dr ying with a hot air str eam. The solidific ation ensur es tha t the fib er is near ly fr ee of solv ent. ANSY S Fluen t’s continuous fib er mo del allo ws you t o analyz e the b ehavior of fib er flo w, fiber pr operties, and c oupling b etween fib ers and the sur rounding fluid due t o the str ong in teraction tha t exists b etween the fib ers and the sur rounding gas . This do cumen t descr ibes the ANSY S Fluen t Continuous F iber mo del. Modeling C ontinuous F ibers provides theor etical back ground inf ormation. The pr ocedur e for setting up and solving fib er spinning flo ws is descr ibed in detail in this chapt er. Only the st eps r elated t o fib er mo deling ar e sho wn her e. Imp ortant Note tha t the c ontinuous fib er mo del is a vailable f or the pr essur e-based solv er, only . For inf ormation ab out inputs r elated t o other mo dels used in c onjunc tion with the fib er mo dels , see the appr opriate sec tions f or those mo dels in the ANSY S Fluen t User's G uide (p.1). 35.1. Installing the C ontinuous F iber M odule 35.2. Loading the C ontinuous F iber M odule 35.3. Getting S tarted With the C ontinuous F iber M odule 35.4. Fiber M odels and Options 35.5. Fiber M aterial P roperties 35.6. Defining F ibers 35.7. User-D efined F unctions (UDFs) f or the C ontinuous F iber M odel 35.8. Fiber M odel S olution C ontrols 35.9. Postpr ocessing f or the C ontinuous F ibers 2515Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.35.1. Installing the C ontinuous F iber M odule The c ontinuous fib er mo del is pr ovided as an add-on mo dule with the standar d ANSY S Fluen t licensed software.The mo dule is installed with the standar d installa tion of ANSY S Fluen t in a dir ectory called addons/fiber in y our installa tion ar ea.The c ontinuous fib er mo dule c onsists of a UDF libr ary and a pre-compiled Scheme libr ary, which must b e loaded and ac tivated b efore calcula tions c an b e performed . 35.2. Loading the C ontinuous F iber M odule The c ontinuous fib er mo dule is loaded in to ANSY S Fluen t thr ough the t ext user in terface (TUI). The module c an b e loaded only when a v alid ANSY S Fluen t case file has b een set or r ead.The t ext command to load the mo dule is define → models → addon-module A list of ANSY S Fluen t add-on mo dules is displa yed: > /define/models/addon-module Fluent Addon Modules: 0. None 1. MHD Model 2. Fiber Model 3. Fuel Cell and Electrolysis Model 4. SOFC Model with Unresolved Electrolyte 5. Population Balance Model 6. Adjoint Solver 7. Battery Module 8. MSMD Battery Module 9. PEM Fuel Cell Model Enter Module Number: [0] 2 Selec t the c ontinuous fib er mo del b y en tering the mo dule numb er 2. During the loading pr ocess a Scheme libr ary containing the gr aphic al and t ext user in terface, and a UDF libr ary containing a set of user-defined func tions (UDFs) ar e loaded in to ANSY S Fluen t. During this pr ocess, you will b e ask ed the question Preset all fiber model specific UDF hooks? [no] If you answ er yes the standar d fib er sour ce term UDFs will b e assigned t o all fluid z ones in y our c ase, and a message will b e reported t o the c onsole windo w confir ming this: Assigning standard fiber source terms to all fluid zones. If you answ er no to pr esetting sour ce term UDFs t o all fluid z ones in the domain, then thr ee options will b e available t o you when setting up sour ce terms f or fluid z ones in y our fib er mo del: no sour ce, constan t sour ce, or UDF sour ce. Note tha t it is y our r esponsibilit y to sp ecify the r est of the settings f or a pr oper fib er simula tion. See Source Term UDF S etup (p.2518 ) for details . If you ar e loading an e xisting c ase file then y ou should answ er the question with no. Other wise , your saved sour ce term settings will b e replac ed b y a UDF . If a mix ture ma terial has b een defined , then y ou will b e ask ed an additional question Preset mass exchange source terms hooks? [no] Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2516Modeling C ontinuous F ibersIf you in tend t o conduc t a dr y spinning simula tion, then y ou should r eply yes . During the loading pr ocess the UDF libr ary for the c ontinuous fib er mo dule is loaded in ANSY S Fluen t. This is r eported t o the c onsole (see b elow).The UDF libr ary also b ecomes visible as a new en try in the UDF Libr ary M anager dialo g box.The basic setup of the c ontinuous fib er mo del is p erformed aut oma t- ically when the fib er mo dule is succ essfully loaded . Opening library "/.../addons/fiber"... Library "/...addons/fiber/lnx86/3d/libudf.so" opened fm_adjust fm_src_mass fm_src_x_mom fm_src_y_mom fm_src_z_mom fm_src_enthalpy fm_src_dom fm_on_demand Done. Addon Module: fiber...loaded! If you did not pr eset the fib er mo del sp ecific UDF ho oks, you will need t o check allo cation of user- defined memor y, hook an adjust func tion (fm_adjust ) to ANSY S Fluen t, and set up the sour ce terms on y our o wn. This is e xplained is User-D efined M emor y and the A djust F unction S etup (p.2518 ). Imp ortant Note tha t user-defined memor y locations f or the fib er mo del will not b e allo cated pr operly if you do not initializ e the flo w field . If you ar e setting up a fib er computa tion based on a converged c ase, you must re-load the ANSY S Fluen t da ta file af ter initializing the solution. The c ontinuous fib er mo dule setup is sa ved with the ANSY S Fluen t case file .The mo dule is loaded automa tically when the c ase file is subsequen tly r ead in to ANSY S Fluen t. Note tha t in the sa ved c ase file, the c ontinuous fib er mo dule is sa ved with the absolut e pa th.Therefore, if the lo cations of the continuous fib er mo dule installa tion or the sa ved c ase file ar e changed , then ANSY S Fluen t will not b e able t o load the mo dule when the c ase file is subsequen tly r ead. In this situa tion, you will ha ve to unload the UDF libr ary using the UDF Libr ary M anager dialo g box after the c ase file is r ead, and then r eload the c ontinuous fib er mo dule .To unload the UDF libr ary go t o the UDF Libr ary M anager dialo g box User D efined → User D efined → Func tions → Manage ... selec t the fib er libr ary under UDF Libr aries, and click Unload . Previously-sa ved c ontinuous fib er mo del setup and par amet ers will b e pr eser ved in this pr ocess. 35.3. Getting S tarted With the C ontinuous F iber M odule The c ontinuous fib er mo del is implemen ted b y user-defined func tions (UDFs) and scheme r outines in ANSY S Fluen t. A numb er of UDFs ar e used t o solv e the fib er equa tions .When y ou loaded the fib er module in the pr evious st ep ( Loading the C ontinuous F iber M odule (p.2516 )), UDF and scheme libr aries that are requir ed b y the c ontinuous fib er mo del w ere aut omatic ally loaded . Before you c an b egin the process of defining y our fib er mo del, however, you will need t o perform some additional setup tasks that involve allo cating user-defined memor y for the UDFs and ho oking an adjust UDF t o ANSY S Fluen t. Follow the pr ocedur e below. For mor e inf ormation, see the f ollowing sec tions: 2517Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Getting S tarted With the C ontinuous F iber M odule35.3.1. User-D efined M emor y and the A djust F unction S etup 35.3.2. Source Term UDF S etup 35.3.1. User-D efined M emor y and the A djust F unc tion S etup 1.Allocate user-defined memor y for the mo del b y incr emen ting the Numb er of U ser-D efined M emor y Location to 8 in the User-D efined M emor y dialo g box. User D efined → User D efined → Memor y... Imp ortant Note tha t you must initializ e your solution (in the Solution Initializa tion task page) in order f or user-defined memor y to be allo cated pr operly. If you ar e setting up a fib er simula tion based on a c onverged c ase, then y ou will ha ve to reload the ANSY S Fluen t data file af ter initializing the solution. 2.Hook the adjust func tion UDF t o ANSY S Fluen t by cho osing fm_adjust::fiber from the dr op-do wn list f or Adjust in the User-D efined F unc tion H ooks dialo g box. User D efined → User D efined → Func tion H ooks ... 35.3.2. Sour ce Term UDF S etup If you answ ered no to pr esetting all fib er mo del-sp ecific UDF ho oks dur ing the loading pr ocess (Loading the C ontinuous F iber M odule (p.2516 )) then y ou will need t o set sour ce terms, individually , for each fluid z one in y our mo del. Alternatively, you c an lea ve the default settings ( none for no sour ce term). For each fluid z one in y our mo del, specify none ,constant , or UDF f or all of the sour ce terms b y following the pr ocedur e below: Setup → Cell Z one C onditions 1.In the Cell Z one C onditions task page , selec t a fluid z one under Zone and click edit ....This op ens the Fluid dialo g box. 2.In the Fluid dialo g box, check Sour ce Terms and click the Sour ce Terms tab . 3.For each of the sour ce terms in the scr oll list ( Mass, X M omen tum , and so on), click the Edit... butt on next to each sour ce term to op en the c orresponding sour ce dialo g box. Leave the default none , or cho ose constant or UDF fr om the dr op-do wn list. Choose the UDF in the dr op-do wn list tha t corresponds t o the par ticular sour ce term. For e xample ,udf fm_src_mass corresponds t o the Mass sour ce term. Use the table b elow (Table 35.1: Source Terms and C orresponding UDFs (p.2518 )) as a r eference guide . Table 35.1: Sour ce Terms and C orresp onding UDFs udf fm_src_mass Mass udf fm_src_x_mom X M omen tum or Axial M omen tum udf fm_src_y_mom Y M omen tum or Radial M omen tum Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2518Modeling C ontinuous F ibersudf fm_src_z_mom Z M omen tum udf fm_src_enthalpy Energy udf fm_src_dom discr ete or dina tes mo del 4.Click OK when all of the UDFs ha ve been ho oked. 5.Repeat this pr ocess f or the r emaining fluid z ones in y our ANSY S Fluen t mo del. Imp ortant If you w ant to include r adia tive in teraction of the fib ers with the discr ete or dina te (DO) radia tion mo del, then the appr opriate sour ce term UDF (udf fm_src_dom ) will b e hooked aut omatic ally when y ou selec t Fiber R adia tion In teraction in the Fiber M odel dialo g box.You must initializ e the solution (which will allo cate memor y for the DO model) b efore the fib er mo del will b e ready to acc ept the fib er radia tion in teraction data. 35.4. Fiber M odels and Options This sec tion pr ovides inf ormation on ho w to cho ose the t ype of fib er mo del y ou w ant to implemen t as w ell as selec t various mo del options tha t are available in ANSY S Fluen t’s fib er mo del. The fib er Model and Options are selec ted in the Fiber M odel dialo g box (Figur e 35.1: The F iber M odel D ialog Box (p.2520 )). Setup → Models → Continuous F iber S pinning Edit... 2519Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Fiber M odels and OptionsFigur e 35.1: The F iber M odel D ialo g Box For mor e inf ormation, see the f ollowing sec tions: 35.4.1. Choosing a F iber M odel 35.4.2. Including In teraction With Sur rounding F low 35.4.3. Including La teral D rag on Sur rounding F low 35.4.4. Including F iber Radia tion In teraction 35.4.5. Viscous H eating of F ibers 35.4.6. Drag, Heat and M ass Transf er C orrelations 35.4.1. Choosing a F iber M odel With ANSY S Fluen t’s fib er mo del, you c an mo del t wo types of fib ers: melt spun and dr y spun. The model y ou cho ose dep ends on the p olymer tha t is used t o dr aw the fib ers. If the fib er p olymer c an be molt en without b eing destr oyed ther mally , then a melt spun fib er pr ocess is t ypic ally used t o pr oduce the fib ers. In such c ases , selec t Melt S pun F ibers under Model in the Fiber M odel dialo g box (Fig- ure 35.1: The F iber M odel D ialog Box (p.2520 )). When the fib er p olymer c an b e liquefied with a suitable solv ent, or the fib er p olymer ’s pr oduc tion process in volves a solv ent, the fib ers ar e formed t ypic ally in a dr y spinning pr ocess. In such c ases , selec t Dry Spun F ibers under Model in the Fiber M odel dialo g box (Figur e 35.1: The F iber M odel D ialog Box (p.2520 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2520Modeling C ontinuous F ibers35.4.2. Including In teraction With S urrounding F low If the fib ers in y our simula tion str ongly influenc e the flo w of the sur rounding fluid and need t o be consider ed, you must selec t Interaction with F luen t under Options in the Fiber M odel dialo g box (Figur e 35.1: The F iber M odel D ialog Box (p.2520 )).When it erating a solution with ANSY S Fluen t, the fiber mo del equa tions ar e solv ed alt ernating with ANSY S Fluen t’s flo w equa tions . Source terms ar e also c omput ed t o couple the fib er equa tions with the fluid flo w equa tions .The c alcula tion of the sour ce terms is p erformed only dur ing the c ourse of an ANSY S Fluen t computa tion. See Coupling Between F ibers and the Sur rounding F luid for a descr iption of the sour ce terms. 35.4.3. Including L ateral D rag on S urrounding F low In typic al fib er simula tions , the axial dr ag of the fib ers is the most imp ortant force ac ting on the fib ers as w ell as on the sur rounding fluid . In some situa tions , the la teral or cr oss-flo w dr ag c an b ecome im- portant.This is the c ase when the fib ers ar e mainly c ooled or dr ied in a cr oss-flo w situa tion. In such cases y ou c an selec t Include L ateral D rag under Options in the Fiber M odel dialo g box (Fig- ure 35.1: The F iber M odel D ialog Box (p.2520 )).The dr ag is estima ted f or a c ylinder in cr oss-flo w and is shown in Equa tion 27.30 . Lateral dr ag is not c onsider ed b y the fib er equa tions and ther efore lateral bending of the fib ers is not c onsider ed. 35.4.4. Including F iber R adia tion In teraction In some situa tions r adia tive hea t exchange is imp ortant. If you ar e using ANSY S Fluen t’s P-1 r adia tion model or ANSY S Fluen t’s discr ete or dina tes (DO) r adia tion mo del, you c an c onsider the eff ects of ir ra- diation on the c ooling and hea ting of the fib ers.When y ou ar e using the DO r adia tion mo del, the eff ects of the fib ers up on the DO mo del c an b e consider ed. If the DO r adia tion mo del is enabled , you c an selec t Fiber R adia tion In teraction (Options group b ox) and en ter the fib er’s Emissivit y in the Prop- erties group b ox (see Figur e 35.1: The F iber M odel D ialog Box (p.2520 )). 35.4.5. Visc ous H eating of F ibers When high elonga tional dr awing r ates ar e combined with lar ge fib er visc osities , visc ous hea ting of fibers ma y become imp ortant.To consider this eff ect in the fib er ener gy equa tion ( Equa tion 27.12 ), you c an selec t Fiber Visc ous H eating under Options in the Fiber M odel dialo g box (Figur e 35.1: The Fiber M odel D ialog Box (p.2520 )). 35.4.6. Drag, Heat and M ass Transf er C orrelations The eff ects of the b oundar y layer of the fib er ar e mo deled in t erms of dr ag, hea t transf er, and mass transf er coefficien ts.These par amet ers ar e sp ecified under Exchange in the Fiber M odel dialo g box (Figur e 35.1: The F iber M odel D ialog Box (p.2520 )). •For the Drag C oefficien t, you c an cho ose b etween const-dr ag,kase-ma tsuo ,gamp ert and user-defined from the dr op-do wn list. If you cho ose const-dr ag, the c onstan t you en ter must b e sp ecified as a dimen- sionless v alue . See Drag C oefficien t for a descr iption of these options . User-defined func tions (UDFs) ar e descr ibed in detail in User-D efined F unctions (UDFs) f or the C ontinuous F iber M odel (p.2536 ). •For the Heat Transf er C oefficien t you c an cho ose b etween const-h tc,kase-ma tsuo-1 ,kase-ma tsuo-2 , gamp ert, and user-defined from the dr op-do wn list. If you cho ose const-h tc, the c onstan t you en ter must be sp ecified SI units of . See Heat Transf er C oefficien t for a descr iption of these options . User- 2521Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Fiber M odels and Optionsdefined func tions (UDFs) ar e descr ibed in detail in User-D efined F unctions (UDFs) f or the C ontinuous F iber Model (p.2536 ). •For the Mass Transf er C oefficien t you c an cho ose b etween const-m tc,kase-ma tsuo-1 ,kase-ma tsuo-2 , gamp ert, and user-defined . If you cho ose const-m tc, you must en ter the mass tr ansf er rate in units of inst ead of the mass tr ansf er coefficien t. See Mass Transf er C oefficien t for a descr iption of these options . User-defined func tions (UDFs) ar e descr ibed in detail in User-D efined F unctions (UDFs) f or the Continuous F iber M odel (p.2536 ). 35.5. Fiber M aterial P roperties For mor e inf ormation, see the f ollowing sec tions: 35.5.1. The C oncept of F iber M aterials 35.5.2. Descr iption of F iber Properties 35.5.1. The C onc ept of F iber M aterials The ma terial pr operties y ou sp ecify f or the fib ers ar e used f or all fib ers defined in y our mo del. You cannot c onsider fib ers c onsisting of diff erent fib er ma terials in one simula tion. The c ontinuous fib er mo del mak es use of ANSY S Fluen t’s ma terial c oncept f or the Material Type of the fluid . Because not all pr operties ar e available in ANSY S Fluen t’s Create/Edit M aterials dialo g box for this ma terial t ype, some additional pr operty inf ormation c an b e pr ovided thr ough the Fiber M odel dialo g box (Figur e 35.1: The F iber M odel D ialog Box (p.2520 )).The pr ocedur e to define the ma terial properties f or the fib ers in y our simula tion is as f ollows: 1.In the Create/Edit M aterials dialo g box, set the Material Type as fluid .This fluid will b e used as the polymer or solv ent in the fib er. 2.Enter all da ta for this ma terial. You c an use all pr ofiles a vailable in the Create/Edit M aterials dialo g box to define the pr operties as func tions of t emp erature. In or der t o in voke user-defined fib er pr operties, you need t o use the UDF t empla te file (see User-D efined F unctions (UDFs) f or the C ontinuous F iber M odel (p.2536 ) for details). UDF acc ess is a vailable f or visc osity, densit y, specific hea t capacit y, ther mal c onduc tivit y and solv ent liquid-v apor equilibr ium pr essur e. 3.Selec t the Polymer in the Materials group b ox of the Fiber M odel dialo g box. 4.For dr y spinning simula tions , you also ha ve to selec t Solvent and the gas phase sp ecies tha t represen ts the Solvent Vapor. 5.Enter an y additional da ta needed f or the fib er ma terial in the Fiber M odel dialo g box. 35.5.2. Descr iption of F iber P roperties The pr operties tha t app ear in the Fiber M odel dialo g box vary dep ending on the fib er mo del t ype. The f ollowing list descr ibes the pr operties y ou ma y need f or a fib er ma terial. For e very pr operty list ed, the dialo g box name is pr ovided wher e the pr operty can b e defined . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2522Modeling C ontinuous F ibersBlending In terval (Fiber M odel dialo g box) is the t emp erature interval used t o comput e an a verage of the fib er visc osities in liquid and solid sta te of Melt S pun F ibers.This option is only a vailable when the Melt S pun F ibers option is selec ted. See Fiber Viscosity for details ab out ho w the Blending In terval is applied t o the fib er viscosity. Cp (Create/Edit M aterials dialo g box) is the sp ecific hea t, , of the fib er in units of ener gy per mass and temp erature. In the c ase of dr y spun fib ers, a mass a verage is c omput ed based on the v alues en tered f or Polymer and its Solvent.You c an use an y of the func tions a vailable t o define t emp erature dep endenc y. If you w ant to use a user-defined func tion pr ofile , you need t o mo dify the UDF t empla te pr ovided b y ANSY S Fluen t. See User-D efined F unctions (UDFs) f or the C ontinuous F iber M odel (p.2536 ) for details . Densit y (Create/Edit M aterials dialo g box) is the densit y, , of the fib er in units of mass p er unit v olume .This densit y is the mass densit y and not the v olume densit y. In the c ase of dr y spun fib ers, a mass a verage is comput ed based on the v alues en tered f or Polymer and its Solvent.You c an use an y of the func tions available t o define t emp erature dep endenc y. If you w ant to use a user-defined func tion pr ofile , you need to mo dify the UDF t empla te pr ovided b y ANSY S Fluen t. See User-D efined F unctions (UDFs) f or the C on- tinuous F iber M odel (p.2536 ) for details . Emissivit y (Fiber M odel dialo g box) is the emissivit y of fib ers in y our mo del, , used t o comput e radia tion hea t transf er to the fib ers ( Equa tion 27.13 ,Equa tion 27.14 ,Equa tion 27.24 and Equa tion 27.25 ) when the P-1 or discr ete or dina tes radia tion mo del is ac tive. Note tha t you must enable r adia tion t o fib er, using the Fiber R adia tion In teraction option in the Fiber M odel dialo g box. Flory Huggins (Fiber M odel dialo g box) can b e enabled t o apply Equa tion 27.3 to comput e the v apor-liquid equilibr ium at the fib er sur face.When it is enabled , you ha ve to sp ecify an appr opriate value f or the dimensionless Flory Huggins par amet er, .This option is only visible when Dry Spun F ibers has b een chosen. Latent Heat (Fiber M odel dialo g box) is the la tent hea t of v aporization of the Solvent when e vaporated fr om a dr y spun fib er. Note tha t you ha ve to en ter the v aporization or r eference temp erature, , wher e the sp ecified value of the la tent hea t has b een measur ed.This v aporization t emp erature is used t o aut oma tically c onsider the change of la tent hea t with t emp erature. See Equa tion 27.16 and Equa tion 27.39 for mor e inf ormation on ho w this is achie ved.These options ar e only visible when Dry Spun F ibers has b een chosen. Solidific ation Temp erature (Fiber M odel dialo g box) is the t emp erature below which the fib er p olymer of a Melt S pun F iber will solidify . It will b e used when c omputing the visc osity of Melt S pun F ibers.This option is only visible when Melt S pun F ibers has b een chosen. Solvent Vapor P ressur e (Fiber M odel dialo g box) is the v apor pr essur e of the solv ent evaporating fr om the fib er sur face in dr y spinning .You ha ve to en ter coefficien ts for an A ntoine-t ype equa tion ( Equa tion 27.38 ). Note tha t the coefficien ts must b e en tered in such units tha t the out come of the A ntoine-t ype equa tion is in P ascal. In addition t o the c oefficien ts of the A ntoine equa tion, you ha ve to en ter the r ange of v alidit y for the v apor pressur e. Below the minimal t emp erature the v apor pr essur e at the minimal t emp erature will b e used . Above the maximal t emp erature, the v apor pr essur e at the maximal t emp erature is used . 2523Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Fiber M aterial P ropertiesThermal C onduc tivit y (Create/Edit M aterials dialo g box) is the ther mal c onduc tivit y, , of the fib er in units of p ower p er length and t emp erature. In the c ase of dr y spun fib ers, a mass a verage is c omput ed based on the v alues en tered for Polymer and its Solvent.You c an use an y of the func tions a vailable t o define t emp erature dep endenc y. If you w ant to use a user-defined func tion pr ofile , you need t o mo dify the UDF t empla te pr ovided b y ANSY S Fluen t. See User-D efined F unctions (UDFs) f or the C ontinuous F iber M odel (p.2536 ) for details . Zero Shear Visc osit y (Create/Edit M aterials dialo g box and/or the Fiber M odel dialo g box, dep ending on the chosen fib er model) is the fib er visc osity, , at zero shear r ate. It is not the elonga tional or Trouton visc osity. For Melt S pun F ibers, you ha ve to en ter the visc osity of the fib er in solid sta te in the Create/Edit Materials dialo g box for the fluid y ou ha ve selec ted as the fib er p olymer .Typic ally this v alue will be very high c ompar ed t o the liquid fib er visc osity to represen t the fib ers as solids . For the solid fiber visc osity you c an mak e use of an y temp erature-dep enden t func tion a vailable in the Create/Edit Materials dialo g box. If you w ant to use a user-defined func tion pr ofile , you need t o mo dify the UDF t empla te pr ovided b y ANSY S Fluen t. See User-D efined F unctions (UDFs) f or the C ontinuous Fiber M odel (p.2536 ) for details . In the Fiber M odel dialo g box, you ha ve to en ter the c oefficien ts for the fib er visc osity in liquid state (Equa tion 27.35 ).To define visc osity as a func tion of fib er v elocity gr adien t, set to a v alue different than 1. In the c ase of Melt S pun F ibers, you also ha ve to en ter da ta for the Solidific ation Temp erature and the Blending In terval.The blending of the visc osities in liquid and solid sta te will b e comput ed based on Equa tion 27.36 . For Dry Spun F ibers you only ha ve to en ter the c oefficien ts for Equa tion 27.37 in the Fiber M odel dialo g box.To sp ecify fib er visc osity as a func tion of fib er v elocity gr adien t, set to a v alue diff erent than 1. Any value en tered in the Create/Edit M aterials dialo g box for visc osities of the fluids used as fib er p olymer and fib er solv ent will not b e consider ed. Note Note tha t dep ending on fib er v elocity gr adien t, the numer ical b ehavior of the F iber Model equa tions ma y become unstable in c ombina tion with fib er visc osity. 35.6. Defining F ibers For mor e inf ormation, see the f ollowing sec tions: 35.6.1. Overview 35.6.2. Fiber Injec tion Types 35.6.3. Working with F iber Injec tions 35.6.4. Defining F iber Injec tion P roperties 35.6.5. Point Properties S pecific t o Single F iber Injec tions 35.6.6. Point Properties S pecific t o Line F iber Injec tions 35.6.7. Point Properties S pecific t o Matrix Fiber Injec tions 35.6.8. Define F iber G rids 35.6.1. Overview The pr imar y inputs tha t you must pr ovide f or the c ontinuous fib er mo del c alcula tions in ANSY S Fluen t are the star ting p ositions , mass flo w rate, tak e up p ositions , and other par amet ers f or each fib er.These Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2524Modeling C ontinuous F ibersprovide the b oundar y conditions f or all dep enden t variables t o be solv ed in the c ontinuous fib er model. The pr imar y inputs ar e: •Start point ( , , coordina tes) of the fib er. •Numb er of fib ers in gr oup . Each defined fib er can r epresen t a gr oup of fib ers tha t will b e used only t o comput e the appr opriate sour ce terms of a gr oup of fib ers. •Diamet er of the fib er no zzle , . •Mass flo w rate per no zzle t o comput e the v elocity of the fib er fluid in the no zzle .The v elocity is used as boundar y condition f or the fib er momen tum equa tion. •Temp erature of the fib er at the no zzle , . •Solvent mass fr action of the fib er fluid in the no zzle .This v alue is used as b oundar y condition f or the solv ent continuit y equa tion. •Take-up p oint ( , , coordina tes) of the fib er. •Velocity or f orce at tak e-up p oint to descr ibe the sec ond b oundar y condition needed f or the fib er momen tum equa tion (see Equa tion 27.4 ). In addition t o these par amet ers, you ha ve to define par amet ers f or the gr id tha t is distr ibut ed b etween the star t position and tak e-up p oint of the fib ers. On this gr id the dep enden t fib er v ariables ar e solv ed, by discr etizing Equa tion 27.1 ,Equa tion 27.4 , and Equa tion 27.11 . You c an define an y numb er of diff erent sets of fib ers pr ovided tha t your c omput er has sufficien t memor y. 35.6.2. Fiber Injec tion Types You will define b oundar y conditions and gr ids f or a fib er b y creating a fib er “injec tion ” and assigning paramet ers t o it. In the c ontinuous fib er mo del the f ollowing t ypes of injec tions ar e pr ovided: •single Use this option t o define a single fib er. •line Use this option when the fib ers y ou w ant to define star t from a line and the star ting p oints ar e located a t constan t intervals on this line . •matrix (only in 3D) Use this option when the fib er star ting p oints ar e ar ranged in the shap e of a r ectangle . •file Use an ASCII file f or en tering c oordina tes and ma terial pr operties of individual fib er injec tions in a tabular f ormat as sho wn b elow. ; 1st commentary line ; 2nd commentary line ; m-th commentary line 2525Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Defining F ibersx1 y1 z1 df1 m1 Tf1 Ys1 x2 y2 z2 df2 m2 Tf2 Ys2 ... ... ... ... ... ... ... xn yn zn dfn mn Tfn Ysn wher e each injec tion is descr ibed b y the f ollowing da ta fields , all on one line , separ ated b y spac es: x, y, and z ar e the C artesian c oordina tes of the injec tion p oint.The z c oordina te must b e included f or b oth 3D and 2D solv ers t o main tain the sequenc e in which the da ta en tries ar e interpreted, however, the z c oordina te is not used in 2D . df is the fib er diamet er m is the mass flo w rate Tf is the t emp erature Ys is the solv ent liquid mass fr action (ignor ed f or melt spinning) You c an include an arbitr ary numb er of c ommen ts an ywher e in the file . Commen tary lines must begin with a semic olon (;). 35.6.3. Working with F iber Injec tions Figur e 35.2: The F iber Injec tions D ialo g Box You will use the Fiber Injec tions dialo g box (Figur e 35.2: The F iber Injec tions D ialog Box (p.2526 )) to create, mo dify, copy, delet e, initializ e, comput e, print, read, write, and list fib er injec tions .To acc ess the Fiber Injec tions dialo g box, first mak e sur e you enable a fib er mo del, then go t o Setup → Models → Fiber-Injec tions Edit... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2526Modeling C ontinuous F ibers35.6.3.1. Creating F iber Injec tions To cr eate a fib er injec tion, click Create. A new fib er injec tion app ears in the Fiber Injec tions list and the Set F iber Injec tion P roperties dialo g box op ens aut oma tically t o enable y ou t o sp ecify the fib er injec tion pr operties (as descr ibed in Point Properties S pecific t o Single F iber Injec tions (p.2533 )). 35.6.3.2. Mo difying F iber Injec tions To mo dify an e xisting fib er injec tion, selec t its name in the Fiber Injec tions list and click Set....The Set F iber Injec tion P roperties dialo g box op ens, and y ou c an mo dify the pr operties as needed . 35.6.3.3. Copying F iber Injec tions To copy an e xisting fib er injec tion t o a new fib er injec tion, selec t the e xisting injec tion in the Fiber Injec tions list and click Copy.The Set F iber Injec tion P roperties dialo g box will op en with a new fiber injec tion tha t has the same pr operties as the fib er injec tion y ou ha ve selec ted.This is useful if you w ant to set another injec tion with similar pr operties. 35.6.3.4. Deleting F iber Injec tions You c an delet e a fib er injec tion b y selec ting its name in the Fiber Injec tions list and click ing Delet e. 35.6.3.5. Initializing F iber Injec tions To initializ e all solution v ariables of the fib ers defined in a fib er injec tion, selec t its name in the Fiber Injec tions list and click Initializ e.The solution v ariables will b e set t o the b oundar y condition v alues at the star ting p oints of the fib ers. You c an selec t several fib er injec tions when y ou w ant to initializ e se veral fib er injec tions a t one time . Imp ortant If you do not selec t a fib er injec tion and click Initializ e, all fib er injec tions will b e initializ ed. 35.6.3.6. Computing F iber Injec tions To solv e the fib er equa tions of a fib er injec tion f or a numb er of it erations , selec t its name in the Fiber Injec tions list and click Comput e.The solution v ariables of the fib ers defined in this fib er injec tion will b e up dated f or the numb er of it erations sp ecified in Figur e 35.13: Fiber S olution C ontrols D ialog Box (p.2543 ). You c an selec t several fib er injec tions when y ou w ant to comput e se veral fib er injec tions a t one time . Imp ortant If you do not selec t a fib er injec tion and click Comput e, all fib er injec tions will b e comput ed. 2527Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Defining F ibers35.6.3.7. Print F iber Injec tions To pr int the fib er solution v ariables of a fib er injec tion in to a file , selec t its name in the Fiber Injec tions list and click Print. A file name is gener ated aut oma tically based on the name of the fib er injec tion and the numb er of the fib er.The solution v ariables of each fib er is st ored in a separ ate file .You ma y use this file f or an e xternal p ostpr ocessing or analy sis of fib er da ta. You c an selec t several fib er injec tions when y ou w ant to pr int several fib er injec tions a t one time . Imp ortant If you do not selec t a fib er injec tion and click Print, all fib er injec tions will b e pr inted. 35.6.3.8. Read D ata of F iber Injec tions To read the da ta (pr operties and solution v ariables) of a fib er injec tion pr eviously st ored in a file , click Read D ata. A file selec tion dialo g box is op ened wher e you c an selec t the name of the file in a list or y ou c an en ter the file name dir ectly.The names of all fib er injec tions included in the file ar e com- pared with the fib er injec tions alr eady defined in the mo del. If the fib er injec tion e xists alr eady in your mo del, you ar e ask ed t o overwrite it. 35.6.3.9. Write Data of F iber Injec tions While the settings of the c ontinuous fib er mo del f or numer ics and mo dels ar e stored in the ANSY S Fluen t case file , the da ta of the fib ers and defined injec tions ha ve to be stored in a separ ate file .To write the da ta of a fib er injec tion t o a file , click Write D ata. A file selec tion dialo g box is op ened wher e you c an selec t the name of an e xisting file t o overwrite it or y ou c an en ter the name of a new file. You c an selec t several fib er injec tions when y ou w ant to store se veral fib er injec tions in one file . Imp ortant If you do not selec t a fib er injec tion and click Write D ata, all fib er injec tions will b e stored in the sp ecified file . 35.6.3.10. Write Binar y Data of F iber Injec tions To wr ite the da ta of a fib er injec tion in binar y format to a file , click Write Binar y Data. A file selec tor dialo g box is op ened wher e you c an selec t the name of an e xisting file t o overwrite it or y ou c an enter the name of a new file . You c an selec t several fib er injec tions when y ou w ant to store se veral fib er injec tions in binar y format in one file . Imp ortant If you do not selec t a fib er injec tion and click Write Binar y Data, all fib er injec tions will be stored in binar y format in the sp ecified file . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2528Modeling C ontinuous F ibers35.6.3.11. List F iber Injec tions To list star ting p ositions and b oundar y conditions of the fib ers defined in a fib er injec tion, click List . ANSY S Fluen t displa ys a list in the c onsole windo w. For each fib er y ou ha ve defined , the list c ontains the f ollowing (in SI units): •File numb er in the injec tion in the c olumn headed (NO) . • , , and position of the star ting p oint in the c olumns headed (X) ,(Y) , and (Z) . •Fiber velocity in the c olumn headed (U) . •Temp erature in the c olumn headed (T) . •Solvent mass fr action in the c olumn headed (SOLVENT) . •Diamet er in the c olumn headed (DIAM) . •Mass flo w rate in the c olumn headed (MFLOW) . •The numb er of fib ers r epresen ted b y this fib er gr oup in the c olumn headed (FIBERS) . •The numb er of fib er gr id cells defined f or this fib er in the c olumn headed (CELLS) . •A notific ation whether the star ting p oint of the fib er is lo cated inside or outside the domain in the c olumn headed (IN DOMAIN?) . The b oundar y conditions a t the tak e up p oint are also list ed.This list c onsists of the f ollowing (in SI units): • , , and position of the tak e-up p oint in the c olumns headed (X) ,(Y) , and (Z) . •Boundar y condition t ype and its sp ecified v alue (VELOCITY for giv en tak e-up v elocity,FORCE for giv en force in the fib er) in the c olumn headed (BOUNDARY CONDITION) . You c an selec t several fib er injec tions when y ou w ant to list se veral fib er injec tions . Imp ortant If you do not selec t a fib er injec tion and click List , all fib er injec tions will b e list ed. 35.6.4. Defining F iber Injec tion P roperties Onc e you ha ve created an injec tion (using the Fiber Injec tions dialo g box, as descr ibed in Creating Fiber Injec tions (p.2527 )), you will use the Set F iber Injec tion P roperties dialo g box (Figur e 35.3: The Set F iber Injec tion P roperties D ialog Box (p.2530 )) to define the fib er injec tion pr operties. (Rememb er that this dialo g box op ens when y ou cr eate a new fib er injec tion, or when y ou selec t an e xisting fib er injec tion and click Set... in the Fiber Injec tions dialo g box.) 2529Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Defining F ibersFigur e 35.3: The S et F iber Injec tion P roperties D ialo g Box The pr ocedur e for defining a fib er injec tion is as f ollows: 1. If you w ant to change the name of the fib er injec tion fr om its default name , enter a new one in the Fiber Injec tion N ame field .This is r ecommended if y ou ar e defining a lar ge numb er of injec tions so y ou c an easily distinguish them. 2. Choose the t ype of fib er injec tion in the Fiber Injec tion Type drop-do wn list. The thr ee choic es (single , line , and matrix) are descr ibed in Fiber Injec tion Types (p.2525 ). 3. Click the Injec tion P oint Properties tab (the default), and sp ecify the p oint coordina tes acc ording t o the fib er injec tion t ype, as descr ibed in Point Properties S pecific t o Single F iber Injec tions (p.2533 )–Point Properties S pecific t o M atrix Fiber Injec tions (p.2533 ). 4. If each of the defined fib ers is r eferring t o a gr oup of fib ers, enter the numb er of fib ers in Numb er of Fibers in G roup . If your no zzle pla te has 400 holes and y ou c an simula te them as a line fib er injec tion with 5 gr oups , you ha ve to en ter a v alue of 80. This means tha t only 5 fib ers ar e solv ed numer ically, but each of these fib ers stands f or 80 fib ers t o be used t o comput e the sour ce terms f or the sur rounding Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2530Modeling C ontinuous F ibersfluid .This enables y ou t o reduc e computing eff orts while achie ving a pr oper coupling with the sur rounding fluid . Imp ortant Note tha t the Numb er of F ibers in G roup is applied t o all fib ers, defined in y our injec- tion. If the numb er of fib er gr oups in y our line or ma trix injec tion is not the same f or all fib ers in this injec tion, you should split this injec tion in to se veral fib er injec tions . 5. Specify the diamet er of the no zzle in the Diamet er field . 6. Enter the mass flo w rate for a single no zzle in the Flow rate per N ozzle field .This will b e used t o comput e the star ting v elocity of the fib er fluid . Imp ortant Note tha t the v alue sp ecified r efers t o one single no zzle and not t o the mass flo w rate of all fib ers defined in this fib er injec tion. 7. Specify the t emp erature of the fib er fluid lea ving the no zzle in the Temp erature field . 8. If you ar e mo deling dr y spun fib ers y ou also ha ve to en ter the solv ent’s mass fr action a t the no zzle in the Solvent Mass F raction field . 2531Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Defining F ibersFigur e 35.4: The S et F iber Injec tion P roperties D ialo g Box With Take-U p Point Properties 9. Click the Takeup P oint Properties tab and en ter the c oordina tes of the tak e-up p oint (see Figur e 35.4: The Set Fiber Injec tion P roperties D ialog Box With Take-Up Point Properties (p.2532 )). Imp ortant Note tha t all fib ers defined in the fib er injec tion ar e collec ted a t the same p oint. If the fibers of y our line or ma trix injec tion v ary in this pr operty, you ha ve to define them using se veral fib er injec tions . 10. Selec t the appr opriate boundar y condition fr om the Boundar y Condition drop-do wn list and sp ecify the v alue f or this b oundar y condition. Choose prescr ibed-v elocity if you k now the dr awing or tak e-up velocity. Choose tensile-f orce if you w ant to pr escr ibe a giv en t ensile f orce in the fib er at the tak e-up point. 11. Click the Grid P roperties tab and en ter all da ta needed t o gener ate the fib er gr id as descr ibed in Define Fiber G rids (p.2534 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2532Modeling C ontinuous F ibers35.6.5. Point Properties S pecific t o Single F iber Injec tions For a single fib er injec tion, you ha ve to sp ecify the c oordina tes of the star ting p oint of the fib er. Click the Injec tion P oint Properties tab and set the , , and coordina tes in the x0,y0, and z0 fields of the Points box. (z0 will app ear only f or 3D pr oblems .) 35.6.6. Point Properties S pecific t o Line F iber Injec tions In a line fib er injec tion the star ting p oints of the fib ers ar e ar ranged on a line a t a c onstan t distanc e (see Figur e 35.5: Line Injec tions (p.2533 )).You ha ve to sp ecify the c oordina tes of the star ting p oint and the end p oint of this line . Click the Injec tion P oint Properties tab in the Set F iber Injec tion P roperties dialo g box (Figur e 35.3: The S et F iber Injec tion P roperties D ialog Box (p.2530 )). In the Points region, set the , , and coordina tes in the x0,y0, and z0 fields f or the star ting p oint of the line and the , , and coordina tes in the x1,y1, and z1 fields f or the end p oint of the line . (z0 and z1 will app ear only for 3D pr oblems .) Figur e 35.5: Line Injec tions In addition t o the c oordina tes, you ha ve to set the numb er of fib ers defined in the line injec tion b y entering the appr opriate value in the Point Densit y Edge1 field . See Figur e 35.5: Line Injec tions (p.2533 ) for an e xample of a line fib er injec tion with a Point Densit y Edge1 of 5. 35.6.7. Point Properties S pecific t o M atrix Fiber Injec tions In a ma trix fib er injec tion the star ting p oints of the fib ers ar e ar ranged in se veral rows ha ving the shap e of a r ectangle or a par allelo gram. Each r ow has the same distanc e to the pr evious and is divided into equal sec tions (see Figur e 35.6: Matrix Injec tions (p.2534 )). You ha ve to sp ecify the c oordina tes of the star ting p oint and the end of p oint of the first r ow and the coordina tes wher e the last r ow should star t. Click the Injec tion P oint Properties tab in the Set F iber Injec tion P roperties dialo g box (Figur e 35.3: The S et F iber Injec tion P roperties D ialog Box (p.2530 )). In the Points region, set the , , and coordina tes in the x0,y0, and z0 fields f or the star ting p oint and the , , and coordina tes in the x1,y1, and z1 fields f or the end p oint of the first r ow of fib ers. The , , and coordina tes of the star ting p oint of the last r ow ha ve to be en tered in the x2,y2, and z2 fields . At each r ow, the numb er of fib ers sp ecified in the Point Densit y Edge1 field ar e injec ted.The numb er of rows to be injec ted is sp ecified in Edge2 . 2533Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Defining F ibersYou c an double check the numb er of fib ers c omput ed in this fib er injec tion if y ou insp ect the Numb ers of F ibers C omput ed field . Imp ortant Note tha t this fib er injec tion t ype is only a vailable f or 3D pr oblems . Figur e 35.6: Matrix Injec tions 35.6.8. Define F iber G rids Each fib er consists of a str aigh t line b etween the injec tion p oint and the tak e-up p oint. It is divided into a numb er of finit e volume c ells. Every fib er defined in a fib er injec tion has its o wn gr id, which you c an sp ecify if y ou click the Grid P roperties tab in the Set F iber Injec tion P roperties dialo g box. 35.6.8.1. Equidistant F iber Grids To define an equidistan t grid for the fib ers selec t equidistan t from the Grid Type drop-do wn list. Specify the Numb er of C ells into which e very fib er of the fib er injec tion will b e divided . Figur e 35.7: Equidistan t Fiber G rid 35.6.8.2. One-S ided F iber Grids A one-sided gr id is gr aded near the injec tion p oint of the fib er.To define a one-sided gr id for the fibers selec t one-sided from the Grid Type drop-do wn list. Specify the Numb er of C ells into which every fib er of the fib er injec tion will b e divided . In addition, you ha ve to sp ecify the r atio, , between each subsequen t fib er cell in the Grid G rowth F actor a t Injec tion P oint field .Values lar ger than 1 refine the gr id, while v alues smaller than 1 c oarsen the gr id. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2534Modeling C ontinuous F ibersFigur e 35.8: One-S ided F iber G rid 35.6.8.3. Two-S ided F iber Grids A two-sided gr id is gr aded near the injec tion p oint as w ell as a t the tak e-up p oint of the fib er.To define a t wo-sided gr id for the fib ers, selec t two-sided from the Grid Type drop-do wn list. Specify the Numb er of C ells into which e very fib er of the fib er injec tion will b e divided .You also ha ve to specify the r atio, , between each subsequen t fib er cell a t the injec tion p oint in the Grid G rowth Factor a t Injec tion P oint field and the r atio, , near the tak e-up p oint in the Grid G rowth F actor at Takeup P oint field .Values lar ger than 1 r efine the gr id, while v alues smaller than 1 will c oarsen it. Figur e 35.9: Two-Sided F iber G rid 35.6.8.4. Three-S ided F iber Grids A thr ee-sided gr id consists of thr ee sides wher e the fib er gr id can b e gr aded .The first side is near the injec tion p oint.The other t wo sides ar e ar ound a r efinemen t point within the fib er gr id. Both sides a t the r efinemen t point are gr aded a t the same r atio b etween the fib er gr id cell lengths .To define a thr ee-sided gr id for the fib ers, selec t three-sided from the Grid Type drop-do wn list (see Figur e 35.11: Defining a Three-S ided F iber G rid U sing the S et F iber Injec tion P roperties D ialog Box (p.2536 )). Specify the Numb er of C ells un til G rid Refinemen t Point, the Grid G rowth F actor a t Injec tion P oint, and the Grid G rowth F actor a t Local G rid Refinemen t Point.You also ha ve to specify the lo cation of the gr id refinemen t point in the Location of L ocal G rid Refinemen t Point field in a dimensionless w ay.The v alue y ou ha ve to en ter is r elative to the fib er length and ma y be between 0 and 1. Values lar ger than 1 r efine the gr id, while v alues smaller than 1 c oarsen the gr id. Click the Comput e butt on t o estima te the Numb er of C ells b ehind G rid Refinemen t Point. 2535Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Defining F ibersFigur e 35.10: Three-S ided F iber G rid Figur e 35.11: Defining a Three-S ided F iber G rid U sing the S et F iber Injec tion P roperties D ialo g Box 35.7. User-D efined F unc tions (UDFs) f or the C ontinuous F iber M odel The c ontinuous fib er mo del enables y ou t o apply cust om c orrelations f or dr ag, hea t transf er, mass transf er coefficien ts, as w ell as ma terial pr operties t o the fib ers b y means of user-defined func tions (UDFs). You ar e pr ovided with a C t empla te file named fiber_fluent_interface.c tha t contains sour ce code f or the dr ag, hea t transf er, mass tr ansf er coefficien t, and the fib er pr operty UDFs .You will need t o mo dify this UDF sour ce file t o suit y our applic ation, compile it , and ho ok the r esulting UDF objec t(s) t o the fib er mo del. This pr ocess is descr ibed b elow. For mor e inf ormation, see the f ollowing sec tions: 35.7.1. UDF S etup Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2536Modeling C ontinuous F ibers35.7.2. Customizing the fib er_fluen t_in terface.c File for Your F iber M odel A pplic ation 35.7.3. Compile F iber M odel UDFs 35.7.4. Hook UDFs t o the C ontinuous F iber M odel 35.7.1. UDF S etup Before you c an edit the UDF t empla te and cr eate your cust om UDF f or dr ag, hea t transf er or mass transf er coefficien t, you must c opy the fiber directory to your w orking dir ectory.The fiber directory contains all of the libr aries and supp ort files tha t are requir ed t o compile UDFs f or the fib er mo del and build shar ed libr aries f or the ar chitecture tha t you sp ecify . 35.7.1.1. Linux S ystems Make a lo cal copy of the fiber directory by copying it fr om the pa th b elow to your w orking dir ectory. path/ansys_inc/v195/fluent/fluent19.5.0/addons/fiber/ wher e path is the dir ectory in which y ou ha ve installed ANSY S Fluen t. 35.7.1.2. Windo ws Systems 1. Open a Visual S tudio .NET DOS pr ompt. 2. Make a lo cal copy of the fiber folder (not a symb olic link) b y copying it fr om the f older b elow to your working f older . path\ANSYS Inc\v195\fluent\fluent19.5.0\addons\fiber\ wher e path is the f older in which y ou ha ve installed ANSY S Fluen t (by default , the pa th is C:\Program Files ). 35.7.2. Customizing the fib er_fluen t_in terface.c File f or Your F iber M odel Applic ation Now tha t you ha ve copied the fiber directory to your w orking dir ectory, you c an edit the UDF templa te file and cust omiz e it t o fit y our mo del needs . 1. In your w orking dir ectory, change dir ectories t o fiber/src .The /src directory contains the UDF templa te sour ce file fiber_fluent_interface.c . 2. In the /src directory, use an y text edit or and edit fiber_fluent_interface.c . 3. Scroll do wn t o the b ottom of the fiber_fluent_interface.c file t o the sec tion tha t contains concatenated func tions f or fr iction fac tor (dr ag c oefficien t), hea t transf er coefficien t, mass tr ansf er coefficien t, fiber visc osity, fiber densit y, fiber ther mal c onduc tivit y, fiber sp ecific hea t, and v apor liquid equilibr ium, respectively.These ar e the UDFs tha t you c an mo dify and cust omiz e. 2537Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User-D efined F unctions (UDFs) f or the C ontinuous F iber M odel4. Edit the func tion(s) y ou r equir e for y our par ticular applic ation. Save fiber_fluent_interface.c and o verwrite the e xisting file . Imp ortant Do not sa ve the file with another name b ecause it will not b e recogniz ed b y the sy stem. Imp ortant The func tion names of the t empla tes user_friction_factor , user_heat_transfer_coefficient , and user_mass_transfer_coeffi- cient must not be alt ered b ecause the y are called b y other r outines in the c ontinuous fiber mo del. 35.7.2.1. Example: Heat Transfer C oefficient UDF Below is an e xample of a hea t transf er coefficien t UDF tha t is defined in fiber_fluent_inter- face.c .The func tion is tak en fr om K ase and M atsuo 253 and is implemen ted as the kase-matsuo- 1 option in the fib er mo del. The func tion name user_heat_transfer_coefficient must not , under an y cir cumstanc es, be alt ered b ecause it is c alled b y other func tions in the c ontinuous fib er model. There ar e two ar gumen ts to the user_heat_transfer_coefficient UDF :Fiber and Loc- al_Fiber_Data_Type .Fiber *f is a p ointer to the fib er str ucture tha t contains inf ormation about the fib er and Local_Fiber_Data_Type *fd acc esses t emp orary variables tha t are needed during the c alcula tion of the fib er. In the sample UDF b elow, a lo op is p erformed o ver all fib er gr id cells using the macr o FIB_N(f) which r epresen ts the numb er of gr id cells f or the fib er f.The R eynolds numb er is c omput ed based on the r elative velocity, (ABS(FIB_C_U(f,i)-fd->up[i]) ); the fib er diamet er, FIB_C_D(f,i) ; the densit y of the sur rounding fluid ,fd->rho[i] and the visc osity of the sur round- ing fluid ,fd->vis[i] .The hea t transf er coefficien t is c omput ed fr om the N usselt numb er using the ther mal c onduc tivit y of the sur rounding fluid , , (fd->k[i] ) and is st ored in fd->alpha[i] . void user_heat_transfer_coefficient(Fiber *f, Local_Fiber_Data_Type *fd) { int i; real Red, Nud; /* model from Kase/Matsuo (1967) */ for (i=0; iFIB_N(f); i++) { /* compute Reynolds number based on relative velocity */ Red = ABS(FIB_C_U(f,i)-fd->up[i])*FIB_C_D(f,i)*fd->rho[i]/fd->vis[i]; Nud = 0.42*pow(Red, 0.334); /* store heat transfer coefficient for latter use */ fd->alpha[i] = Nud*fd->k[i]/FIB_C_D(f,i); } } All variables and macr os tha t are used in user_heat_transfer_coefficient are defined in header files pr ovided with the c ontinuous fib er mo del. For e xample , you will find the t ype definition Fiber and the macr os tha t are used t o acc ess v ariables of a single fib er in the header file fiber.h . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2538Modeling C ontinuous F ibersTemp orary variables used in the t ype definition of Local_Fiber_Data_Type can b e found in the header file fib-mem.h . Imp ortant Note tha t you must not mo dify the header files pr ovided with the c ontinuous fib er mo del. Other wise the c ompiled libr ary will not b e compa tible with ANSY S Fluen t and will sho w run time er rors. 35.7.2.2. Example: Fiber Sp ecific H eat C apacit y UDF You c an also c alcula te fib er ma terial pr operties using UDFs . ANSY S Fluen t provides a UDF t empla te for e very fib er pr operty.You c an mo dify the UDF t empla tes for y our sp ecific c ase. The t empla te for the fib er densit y is as f ollows: real User_Fiber_Specific_Heat(Fiber *f, real temp, real liq, int i) { real yi[MAX_SPE_EQNS]; real cp_p; /* compute cp based on FLUENT's standard procedure selected in materials panel */ cp_p = Specific_Heat(FIB_MATERIAL_POLYMER(f), temp, 0., yi); if (FIB_DRY_SPINNING(f)) { real cp_s; cp_s = Specific_Heat(FIB_MATERIAL_SOLVENT(f), temp, 0., yi); return cp_p*(1.-liq)+cp_s*liq; } return cp_p; } Imp ortant The func tion names of the t empla tes User_Friction_Factor ,User_Heat_Trans- fer_Coefficient ,User_Mass_Transfer_Coefficient ,User_Fiber_Viscos- ity ,User_Fiber_Density ,User_Fiber_Thermal_Conductivity , User_Fiber_Specific_Heat , and User_Fiber_Vle must not b e alt ered sinc e the y are called b y other r outines of the c ontinuous fib er mo del. All variables and macr os defined in the header files ar e pr ovided with the c ontinuous fib er mo del. For e xample , you will find the t ype definition Fiber and the macr os to acc ess v ariables of a single fiber in the header file fiber.h .The t emp orary variables used in the t ype definition of Loc- al_Fiber_Data_Type can b e found in the header file fib-mem.h . Imp ortant You must not mo dify the header files pr ovided with the c ontinuous fib er mo del. Other wise the c ompiled libr ary will not b e compa tible with ANSY S Fluen t resulting in r untime er rors (messages will b e pr inted in the c onsole). 2539Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User-D efined F unctions (UDFs) f or the C ontinuous F iber M odel35.7.3. Compile F iber M odel UDFs Onc e you ha ve cust omiz ed the UDF t empla te fiber_fluent_interface.c for y our fib er mo del applic ation, you ar e no w ready to compile the sour ce file using the t ext interface. Follow the pr ocedur e below for Linux S ystems and Windo ws Systems , respectively. 35.7.3.1. Linux S ystems In the /fiber in y our w orking dir ectory, run the make command tha t will c ompile y our fib er mo de UDF and build a shar ed libr ary for the ar chitecture you ar e running .To do this , type the f ollowing command a t the pr ompt: make -f Makefile-client FLUENT_ARCH=your_arch wher e your_arch is replac ed b y the ar chitecture of the machine y ou ar e running (f or e xample , lnx86). For e xample , if y our c omput er ar chitecture is lnx86 type the f ollowing c ommand in a t erminal session: make -f Makefile-client FLUENT_ARCH=lnx86 To iden tify the ar chitecture of the machine y ou ar e running on, scroll up the ANSY S Fluen t console windo w to the message tha t begins with “Starting ”. When y ou r un the make process, the sour ce code (fluent_fiber_interface.c ) will b e compiled into objec t code and a shar ed libr ary will b e built f or the c omput er ar chitecture and v ersion of ANSY S Fluen t you ar e running . Messages ab out the c ompile/build pr ocess will b e displa yed on the c onsole windo w.You c an view the c ompila tion hist ory in the lo g file tha t is sa ved in y our w orking dir ectory. Below is an e xample of c onsole messages f or a lnx86 ar chitecture running a 2D v ersion of ANSY S Fluen t. Working... for d in lnx86[23]*; do \ ( \ cd $d; \ for f in ../../src*.[ch] ../../src/makefile; do \ if [ ! -f ’basename $f’ ]; then \ echo "# linking to " $f "in" $d; \ ln -s $f .; \ fi; \ done; \ echo ""; \ echo "# building library in" $d; \ make -kmakelog 2&1; \ cat makelog; \ ) \ done # linking to ... myudf.c in lnx86/2d # building library in lnx86/2d make[1]: Entering directory ..../udf_names.c # Generating udf_names make[2]: Entering directory ..../fluent_fiber_interface.c make libudf.so ... # Compiling udf_names.o ... # Compiling profile.o ... # Linking libudf.so ... make[2]: Leaving directory ..../udf_names.c make[1]: Leaving directory ..../fluent_fiber_interface.c You can also see the ’log’-file in the working directory for compilation history Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2540Modeling C ontinuous F ibers Done. 35.7.3.2. NT/W indo ws Systems 1.Make a lo cal copy of the fiber folder . Do not cr eate a shor tcut. a.Create a dir ectory for the cust om fiber libr aries (f or e xample ,/home/custom-build ). b.Copy the fiber libr ary from the installa tion of ANSY S Fluen t (Ansys Inc\v195\fluent\flu- ent19.5.0\addons ) to your newly cr eated dir ectory. 2.Open the Visual S tudio .NET DOS pr ompt (see Compiler R equir emen ts for Windo ws Systems in the ANSY S, Inc . Installation G uides for compilers tha t are compa tible with ANSY S Fluen t). 3.Set the FLUENT_INC environmen t variable t o the cur rent ANSY S Fluen t installa tion dir ectory, for e xample: FLUENT_INC=" \ANSYS Inc\v195\fluent" wher e is the tar get dr ive lett er including the c olon (f or e xample ,D:). 4.Enter the fiber\src folder : cd fiber/src 5.Make changes t o the fiber_fluent_interface.c file. 6.Retur n to the fiber folder : cd .. 7.Issue the f ollowing c ommand in the c ommand windo w: build_fiber_udf.bat 8.Define the FLUENT_ADDONS environmen t variable t o correspond t o your cust omiz ed v ersion of the continuous fib er mo dule in one of f ollowing w ays: •Set the pa th to FLUENT_ADDONS globally . •In the Environmen t tab of F luen t Launcher , enter inf ormation f or FLUENT_ADDONS in the Other Environmen t Variables field , for e xample: FLUENT_ADDONS= \home\custom-build wher e is the tar get dr ive lett er including the c olon (f or e xample ,D:). Note that ther e should b e no spac es in the ab ove pa th. 35.7.4. Hook UDFs t o the C ontinuous F iber M odel Onc e you ha ve succ essfully c ompiled y our c ontinuous fib er mo del UDF(s), the user-defined option will app ear in dr op-do wn lists f or par amet ers under Exchange in the Fiber M odel dialo g box (Fig- ure 35.12: The F iber M odel D ialog Box (p.2542 )).To ho ok y our UDF t o a par ticular fib er mo del par amet er, 2541Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.User-D efined F unctions (UDFs) f or the C ontinuous F iber M odelsimply selec t user-defined from the dr op-do wn list f or Drag C oefficien t,Heat Transf er C oefficien t, or Mass Transf er C oefficien t and click OK. If you w ant to use UDFs t o define fib er ma terial pr operties, selec t the Enable UDF P roperties check box, and then enable individual pr operty UDFs under the User D efined P roperties group b ox. Figur e 35.12: The F iber M odel D ialo g Box 35.8. Fiber M odel S olution C ontrols To acc ess the Fiber S olution C ontrols dialo g box, go t o Setup → Models → Fiber-C ontrols Edit... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2542Modeling C ontinuous F ibersFigur e 35.13: Fiber S olution C ontrols D ialo g Box The Fiber S olution C ontrols dialo g box enables y ou t o set c ommon solution par amet ers f or the fib er equa tions and their c oupling with the sur rounding fluid . Solve is used t o enable and disable the solution of the fib er equa tions f or Momen tum (Equa tion 27.4 ),Energy (Equa tion 27.11 ), and Species (Equa tion 27.1 ).When swit ching off the solution of one of these equa tions , it is not c omput ed f or an y fib ers defined in y our mo del. Discr etiza tion provides a dr op-do wn list wher e you c an assign t o each of the fib er equa tions one of thr ee diff erent dis- cretiza tion schemes e xplained in Discretiza tion of the F iber Equa tions . Under relaxa tion contains all under-r elaxa tion fac tors f or all fib er equa tions tha t are being solv ed in the c ontinuous fib er model. See Under-R elaxa tion for additional back ground inf ormation and see Solution S trategies for ho w to mak e use of under-r elaxa tion fac tors in y our solution str ategy. Convergenc e Criterion is used t o stop the fib er it erations when the r esiduals of all fib er equa tions ar e below the pr escr ibed cr iteria. You c an define a separ ate convergenc e criterion f or e very fib er equa tion. Check C onvergenc e must b e tur ned on if y ou w ant to compar e the r esiduals of the fib er equa tions with the Convergenc e Criterion. If you tur n this option off , the giv en numb er of fib er it erations will b e comput ed. Rela tive Residuals are used t o comput e the change of the r esidual of t wo subsequen t iterations r elative to the r esidual of the last it eration b y applying Equa tion 27.20 .The r esult of this is c ompar ed t o the Convergenc e Criterion to check whether c onvergenc e has b een achie ved. 2543Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Fiber M odel S olution C ontrolsIterations defines the numb er of Fiber Iterations performed e very time the fib er equa tions ar e up dated. Rep orting In terval sets the numb er of fib er it erations tha t will pass b efore the r esiduals will b e pr inted. You c an r educ e the output t o the last fib er it eration b y sp ecifying Rep orting In terval as 0. This is recommended when p erforming a solution tha t is c oupled with the sur rounding flo w. Numb er of F luen t Iterations p er F iber C omputa tion sets the numb er of F luen t iterations b efore the fib er equa tions ar e up dated in a solution tha t is c oupled with the sur rounding flo w. Sour ce Term U nder relaxa tion factor is used t o under-r elax the fib er sour ce term exchange t o the sur rounding fluid . In a c onverged solution this v alue do es not influenc e your pr edic tions . For additional inf ormation on ho w to set and cho ose v alues f or the options in the Fiber S olutions Control dialo g box, see Solution S trategies . 35.9. Postpr ocessing f or the C ontinuous F ibers After y ou ha ve complet ed y our inputs and p erformed an y coupled c alcula tions , you c an displa y the location of the fib ers and sour ce terms of the fib ers, and y ou c an wr ite fib er da ta to files f or fur ther analy sis of fib er v ariables . The f ollowing da ta can b e displa yed using gr aphic al and alphanumer ic reporting facilities: •Graphic al displa y of fib er lo cations •Exchange t erms with sur rounding fluid •Fiber solution v ariables . For mor e inf ormation, see the f ollowing sec tions: 35.9.1. Displa y of F iber Locations and G rid Points 35.9.2. Exchange Terms of F ibers 35.9.3. Analyzing F iber Variables 35.9.4. Running the F iber M odule in P arallel 35.9.1. Displa y of F iber L ocations and G rid P oints When y ou ha ve defined fib er injec tions , as descr ibed in Defining F ibers (p.2524 ), you c an displa y the location of the fib ers using ANSY S Fluen t’s Contour plot facilit y (Figur e 35.14: Displa ying F iber L ocations Using the C ontours D ialog Box (p.2545 )). Results → Graphics → Contours Edit... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2544Modeling C ontinuous F ibersFigur e 35.14: Displa ying F iber L ocations U sing the C ontours D ialo g Box In the Contours of drop-do wn list , selec t Custom F ield F unc tions ..., then selec t fiber-lo cation .The values in this field ar e between z ero and the numb er of fib er cells in an ANSY S Fluen t grid cell. You ma y gener ate iso-sur faces of c onstan t values of fiber-lo cation to displa y the fib ers in 3D pr oblems . You c an also displa y the lo cations of the fib ers and their gr id discr etiza tion using the Fiber M esh Displa y dialo g box, which c an b e acc essed fr om the Results /Graphics /Fiber M esh tree it em. 2545Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Postpr ocessing f or the C ontinuous F ibersFigur e 35.15: The F iber M esh D ispla y D ialo g Box The f ollowing mesh discr etiza tion options ar e available: •Nodes: displa ys the end p oints of fib er volume c ells •Edges : displa ys a line along the pa th of fib ers in the domain •Draw Fluen t mesh : Enables the displa y of the CFD mesh geometr y with the mesh displa y settings sp ecified in the Mesh D ispla y dialo g box.The Mesh D ispla y dialo g box will app ear aut oma tically when y ou enable the Draw Fluen t mesh option. You c an set the fib er Line Width in the Fiber S tyle A ttribut e dialo g box acc essed b y click ing the Style A ttribut es... butt on. Figur e 35.16: The F iber S tyle A ttribut es D ialo g Box For the injec tions selec ted in the Fiber Injec tions selec tion list , you c an displa y either all injec tion fibers or single fib ers with a sp ecified Fiber ID (when the Show S ingle F iber option is selec ted). 35.9.2. Exchange Terms of F ibers The c ontinuous fib er mo del c omput es and st ores the e xchange of momen tum, hea t, mass , and r adia tion in each c ontrol volume in y our ANSY S Fluen t mo del. You c an displa y these v ariables gr aphic ally b y Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2546Modeling C ontinuous F ibersdrawing c ontours , profiles , and so on. They all ar e contained in the Custom F ield F unc tions ... categor y of the v ariable selec tion dr op-do wn list tha t app ears in p ostpr ocessing dialo g boxes: fiber-mass-sour ce defined b y Equa tion 27.22 . fiber-x-momen tum-sour ce is the x-c omp onen t of the momen tum e xchange , defined b y Equa tion 27.21 . fiber-y-momen tum-sour ce is the y-c omp onen t of the momen tum e xchange , defined b y Equa tion 27.21 . fiber-z-momen tum-sour ce is the z-c omp onen t of the momen tum e xchange , defined b y Equa tion 27.21 . fiber-ener gy-sour ce defined b y Equa tion 27.23 . fiber-dom-absor ption defined b y Equa tion 27.24 . fiber-dom-emission defined b y Equa tion 27.25 . Note tha t these e xchange t erms ar e up dated and displa yed only when c oupled c omputa tions ar e performed . 35.9.3. Analyzing F iber Variables You c an use ANSY S Fluen t’s Plot facilities t o analyz e fib er solution v ariables such as fib er v elocity, temp erature, diamet er, and so on. 35.9.3.1. XY Plots To in vestiga te fib er v ariables y ou ha ve to gener ate an x y-file f or e very variable using the f ollowing procedur e from the t ext command in terface (assuming tha t you ha ve alr eady defined a fib er injec tion): 1. Store an x y-file with the v ariable of in terest. continuous-fiber → print-xy 2. Enter the fib er injec tion of in terest when ask ed f or Fiber Injection name> 3. Specify a v ariable f or x-column .This will b e used as abscissa in the file plot. 4. Specify another v ariable f or y-column , which will b e used as or dina te in the file plot. 5. Specify a file name when ask ed f or XY plot file name . 6. Load the file with ANSY S Fluen t’s xy plot facilities , descr ibed in the ANSY S Fluen t manual. The f ollowing v ariables c an b e en tered as x-column and y-column : 2547Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Postpr ocessing f or the C ontinuous F ibers•axial dr ag •conduc tivit y •curvature •diamet er •enthalp y •evaporated mass flux •heat transf er coefficien t •lateral dr ag •length •mass flo w •mass fr action •mass tr ansf er coefficien t •Nusselt numb er •Sherwood numb er •Reynolds numb er •specific hea t •surface mass fr action •temp erature •tensile f orce •user v ariable •velocity •velocity gr adien t •viscosity If a fib er injec tion c onsists of se veral fib ers, the da ta of all fib ers in this fib er injec tion will b e stored in the x y-file . In addition t o this , you c an st ore a fib er hist ory file f or a fib er injec tion as descr ibed in Print Fiber In- jections (p.2528 ).This c an b e used t o analyz e a single fib er using ANSY S Fluen t xy-plot facilities or b y external p ostpr ocessing pr ograms . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2548Modeling C ontinuous F ibers35.9.3.2. Fiber D ispla y To visualiz e injec tion fib ers, you c an use the Fiber D ispla y dialo g box, which c an b e acc essed fr om the Results /Graphics /Fibers tree it em. Figur e 35.17: The F iber D ispla y D ialo g Box The Fiber D ispla y dialo g box off ers the same displa y options as those in the Fiber M esh D ispla y dialo g box (Figur e 35.15: The F iber M esh D ispla y Dialog Box (p.2546 )). Similar ly, for the injec tions selec ted 2549Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Postpr ocessing f or the C ontinuous F ibersin the Fiber Injec tions selec tion list , you c an displa y either all injec tion fib ers or single fib ers with a specified Fiber ID (when the Show S ingle F iber option is selec ted). You c an c olor the fib ers b y the fib er v ariables list ed in XY Plots (p.2547 ) or b y the f ollowing additional fiber v ariables: •Fiber ID •Fiber D ensit y •Fiber Tension You c an c ontrol the smo oth gr adation of fib er colors b y sp ecifying the numb er of fib er Levels. 35.9.4. Running the F iber M odule in P arallel The F iber M odule c an b e used in ser ial as w ell as in par allel c alcula tions . Simula tions in par allel r equir e no additional input. The fib er it erations ar e performed en tirely on the host pr ocess, wher eas the flo w field is par alleliz ed. As a r esult , the o verall p erformanc e ma y be limit ed b y the host pr ocess if the fib er calcula tions ar e mor e time-c onsuming than the par allel flo w-field it erations .Therefore, when simula ting a lar ge numb er of fib ers, it is r ecommended t o spa wn the host pr ocess on a suitable machine . Refer to Parallel P rocessing in the Fluent U ser's G uide (p.3045 ) for fur ther inf ormation on ho w to set up par allel calcula tions . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2550Modeling C ontinuous F ibersChapt er 36: Creating Reduc ed Or der M odels (R OMs) You c an use a stand-alone F luen t session t o define a r educ ed or der mo del (R OM) f or pr oduc tion in the ANSY S Workbench en vironmen t (thr ough ANSY S DesignXplor er).The pr oduced R OM c an then b e con- sumed in the R OM Viewer. You c an cr eate a R OM fr om a ser ies of 2D or 3D simula tions .The R OM is a ma thema tical appr oxima tion of y our full mo del, wher e you c an change some inputs and get the solution immedia tely.These inputs are defined as input par amet ers in ANSY S Fluen t and c an b e ma terial pr operties, inlet v elocities , pressur es and so on. The pr ocess of cr eating and analyzing R OMs c an b e br oken in to two par ts: •ROM P roduc tion—Y ou c an setup a R OM c ase in stand alone F luen t and r ead this c ase in to Fluen t in Work- bench, as descr ibed in Defining a R OM (p.2551 ) and ROM P roduc tion in the DesignXplor er U ser's G uide . •ROM C onsumption—T he pr oduced R OM c an b e consumed in the R OM Viewer (ROM C onsumption in the DesignXplor er U ser's G uide ). To lear n mor e ab out R OMs , refer to Using R OMs in the DesignXplor er U ser's G uide . 36.1. Defining a R OM Imp ortant For release 2019 R3, ROMs ar e only applic able f or st eady-sta te, Newtonian fluids without shock w aves (M a<1) or r adia tion. Building a R OM in F luen t: 1.Enable the R OM addon mo dule b y en tering define/models/addon-module/11 in the F luen t console . 2.Initializ e the c ase or r ead a da ta file . Solution → Initializa tion → Initializ e File → Read → Data... 3.Create input par amet ers f or the quan tities of in terest f or the R OM. You c an cho ose any input par amet ers that y ou ar e int erested in. Later, in the 3D R OM syst em, you c an deselec t input par amet ers if y ou decide that ther e ar e par amet ers that y ou no longer w ant t o vary. Note that if y ou pick t oo many input par amet ers y ou ma y requir e additional snapshots t o maintain accur acy 2551Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.with the R OM. Refer to Creating a N ew P aramet er (p.845 ) for additional inf ormation on cr eating input par amet ers. Note Gener al guidanc e on the numb er of input par amet ers defined: •Low: 1 to 2 •Medium: 3 to 6 •High: mor e than 7 •Very high: mor e than 15 4.Create at least one output par amet er. The output par amet er has no impac t on the R OM, but y ou c an use it t o monit or the r esults while the design p oints ar e being up dat ed in ANSY S D esignXplor er. Refer to Creating O utput P aramet ers (p.2935 ) for additional inf ormation on output par amet ers. 5.Enable the Reduc ed Or der M odel. Setup → Models Reduc ed Or der M odel → Edit... Figur e 36.1: The Reduc ed Or der M odel D ialo g Box 6.Selec t your desir ed Variables and Zones and click Add>> .Any Custom F ield F unc tions (p.3038 ) that y ou ha ve defined ar e available f or selec tion. You c an r emo ve items fr om the Selec ted for R OM list b y selec ting them and click ing Delet e. Imp ortant •You ar e free to selec t all of the v ariables and z ones tha t you ar e interested in, however, be aware tha t if y ou selec t too man y variables/z ones , you will end up with bigger files .This is Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2552Creating R educ ed Or der M odels (R OMs)especially tr ue if y ou ha ve a lar ger mo del. For par ticular ly lar ge mo dels , you ma y want to selec t smaller z ones tha t adequa tely c aptur e the ph ysics of in terest. •You must selec t the v ariables tha t correspond or ar e asso ciated with the input and output paramet ers tha t you ha ve defined . For e xample , if you ha ve Mass F low R ate selec ted as an output par amet er, then y ou must ha ve Velocity selec ted in the Variable list (b ecause mass flow rate = densit y * ar ea * v elocity). 7.Review the selec tions y ou ha ve made in the Selec ted f or R OM list and click OK to confir m. 36.2. Reduc ed Or der M odel (R OM) E valua tion in F luen t Apart from viewing r esults in the R OM Viewer, you ma y want to quick ly visualiz e the r esults dir ectly within F luen t, which y ou c an do when y ou ar e running F luen t in Workbench. From within F luen t you c an view : •Contours •Vectors •Pathlines •XY Plots •Surface and v olume in tegral reports To evalua te a R OM in F luen t: 1.In Workbench, gener ate the romz file b y right-click ing the ROM Builder cell and selec ting Export ROM. Save the romz file t o your desir ed lo cation. 2553Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Reduc ed Or der M odel (R OM) E valua tion in F luen t2.Right-click the F luen t Setup cell, and selec t Imp ort ROM → Browse, to op en the Selec t File dialo g box and imp ort the romz file. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2554Creating R educ ed Or der M odels (R OMs)3.Gener ate the solution in F luen t by click ing Update Projec t in the t oolbar . 4.Launch F luen t by double-click ing the Solution cell. 5.Open the Reduc ed Or der M odel dialo g box. → Setup → Models → ROM Edit... 6.Click the Evalua te tab .Here you c an see all of the par amet ers used in cr eating the R OM. The r ange of acc eptable inputs is list ed t o the r ight of each v ariable . 2555Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Reduc ed Or der M odel (R OM) E valua tion in F luen t7.Enter a v alue f or the v ariable y ou w ant evalua ted (within the allo wed r ange) and click Evalua te. You c an visually p ostpr ocess R OM v ariables using c ontour plots , vector plots , and so on. 1.Open the Contours dialo g box. → Results → Graphics → Contours New... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2556Creating R educ ed Or der M odels (R OMs)2.Ensur e tha t Node Values are disabled .ROMs ar e evaluat ed at c ell c enters. 3.Selec t ROM C ell F unc tions ... from the Contours of drop-do wn list. Note The ROM C ell F unc tions ... option is only a vailable af ter y ou click Evalua te in the Evalua te tab of the Reduc ed Or der M odel dialo g box. 4.Selec t the R OM v ariable tha t you w ant to visualiz e from the sec ond Contours of drop-do wn list. 5.Selec t the sur faces wher e you w ant to visualiz e the sp ecified R OM v ariable .The list of a vailable sur faces is filtered t o sho w onl y the sur faces wher e the R OM is e valuat ed, as defined dur ing R OM setup . 6.Click Save/D ispla y. Limita tions The f ollowing limita tions apply t o postpr ocessing r educ ed or der mo dels in F luen t: •You c annot c ontinue with the R OM solution af ter evalua ting it. •Exporting solution da ta/v ariables will not include R OM snapshot da ta. •Flux and F orce Reports ar e not a vailable f or R OM e valua ted v ariables using R OM da ta. •Output par amet ers ar e not up dated f or D esign of Exp erimen ts when the R OM is b eing e valua ted in F luen t. 36.3. ROM Limita tions The f ollowing list of limita tions should b e view ed in c onjunc tion with the list of limita tions pr ovided in the ANSY S DesignXplor er do cumen tation ( ROM Limita tions and K nown I ssues in the DesignXplor er U ser's Guide ): •You must ha ve at least one input and one output par amet er defined b efore you c an enable the r educ ed order mo del in F luen t. •Polyhedr al meshes ar e supp orted in the R OM Viewer, however the y will b e displa yed with tr iangles . Note that this do es not aff ect the r esults . •The R OM Viewer do es not supp ort displa ying r esults on edges—it c an only displa y results on elemen ts and faces. •Interface zones ar e not a vailable f or use with R OMs . •The 3D R OM do es not supp ort geometr y par amet er up dates. •ROMs c an only b e created f or st eady-sta te cases . •Combustion and r adia tion mo dels ar e not supp orted f or R OMs . •Parametr ic optimiza tion using the R OM thr ough F luen t is not supp orted. 2557Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.ROM Limita tions•Moving and def orming meshes ar e not supp orted f or R OMs . •You must selec t the v ariables tha t correspond with the input and output par amet ers tha t you ha ve defined . •Contours in F luen t and the R OM Viewer:While c ontour displa ys ma y app ear similar in F luen t and the R OM Viewer, ther e are some k ey diff erences in ho w the y displa y da ta tha t could app ear t o sho w inc onsist encies that are not ac tually pr esen t in the r esults . In F luen t, contours ar e displa yed using no de v alues (b y default) or cell-c enter values if no de v alues ar e disabled . In c ontrast, the R OM Viewer displa ys contours using fac e values (not an option in F luen t). In most c ases , node v alues c an app ear v ery compar able t o fac e values , but ther e are some instanc es wher e tha t is not the c ase. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2558Creating R educ ed Or der M odels (R OMs)Chapt er 37: Using the S olver This chapt er descr ibes ho w to use the ANSY S Fluen t solv er. For mor e inf ormation ab out the theor y behind the ANSY S Fluen t solv er, see Solver Theor y in the Theor y Guide .Choosing the S olver (p.2561 ) provides an o verview , and the r emaining sec tions pr ovide detailed instr uctions . 37.1. Overview of U sing the S olver 37.2. Choosing the S patial D iscretiza tion Scheme 37.3. Pressur e-Based S olver Settings 37.4. Densit y-Based S olver Settings 37.5. Setting A lgebr aic M ultigr id Paramet ers 37.6. Setting S olution Limits 37.7. Setting M ulti-S tage Time-S tepping P aramet ers 37.8. Selec ting G radien t Limit ers 37.9. Initializing the S olution 37.10. Full M ultigr id (FMG) Initializa tion 37.11. Hybrid Initializa tion 37.12. Performing S teady-State Calcula tions 37.13. Performing P seudo Transien t Calcula tions 37.14. Performing Time-D ependen t Calcula tions 37.15. Monit oring S olution C onvergenc e 37.16. Convergenc e Conditions 37.17. Executing C ommands D uring the C alcula tion 37.18. Automa tic Initializa tion of the S olution and C ase M odific ation 37.19. Anima ting the S olution 37.20. Check ing Your C ase S etup 37.21. Convergenc e and S tabilit y 37.22. Solution S teering 37.1. Overview of U sing the S olver In ANSY S Fluen t, two solv er technolo gies ar e available: •pressur e-based •densit y-based Both solv ers c an b e used f or a br oad r ange of flo ws, but in some c ases one f ormula tion ma y perform better (tha t is, yield a solution mor e quick ly or r esolv e certain flo w features b etter) than the other .The pressur e-based and densit y-based appr oaches diff er in the w ay tha t the c ontinuit y, momen tum, and (wher e appr opriate) ener gy and sp ecies equa tions ar e solv ed, as descr ibed in Overview of F low Solvers in the Theor y Guide . The pr essur e-based solv er tr aditionally has b een used f or inc ompr essible and mildly c ompr essible flo ws. The densit y-based appr oach, on the other hand , was or iginally designed f or high-sp eed c ompr essible flows. Both appr oaches ar e no w applic able t o a br oad r ange of flo ws (fr om inc ompr essible t o highly compr essible), but the or igins of the densit y-based f ormula tion ma y giv e it an accur acy (tha t is sho ck resolution) ad vantage o ver the pr essur e-based solv er for high-sp eed c ompr essible flo ws. 2559Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Two formula tions e xist under the densit y-based solv er: implicit and e xplicit. The densit y-based e xplicit and implicit f ormula tions solv e the equa tions f or additional sc alars (f or e xample , turbulenc e or r adia tion quan tities) sequen tially .The implicit and e xplicit densit y-based f ormula tions diff er in the w ay tha t the y linear ize the c oupled equa tions . For mor e details ab out the solv er formula tions , see Overview of F low Solvers in the Theor y Guide . Due t o br oader stabilit y char acteristics of the implicit f ormula tion, a converged st eady-sta te solution can b e obtained much fast er using the implicit f ormula tion r ather than the e xplicit f ormula tion. However, the implicit f ormula tion r equir es mor e memor y than the e xplicit f ormula tion. Two algor ithms also e xist under the pr essur e-based solv er in ANSY S Fluen t: a segr egated algor ithm and a coupled algor ithm. In the segr egated algor ithm the go verning equa tions ar e solv ed sequen tially , se- gregated fr om one another , while in the c oupled algor ithm the momen tum equa tions and the pr essur e- based c ontinuit y equa tion ar e solv ed in a c oupled manner . In gener al, the c oupled algor ithm signific antly impr oves the c onvergenc e sp eed o ver the segr egated algor ithm, however, the memor y requir emen t for the c oupled algor ithm is mor e than the segr egated algor ithm. When selec ting a solv er and an algor ithm y ou must c onsider the f ollowing issues: •The mo del a vailabilit y for a giv en solv er. •Solver p erformanc e for the giv en flo w conditions . •The siz e of the mesh under c onsider ation and the a vailable memor y on y our machine .This issue c ould b e an imp ortant fac tor in deciding whether t o use an e xplicit or implicit f ormula tion when the densit y-based solv er is selec ted, or t o use a segr egated or c oupled algor ithm when the pr essur e-based solv er is selec ted. The f ollowing t wo lists highligh t the mo del a vailabilit y for each solv er: Imp ortant Note tha t the pr essur e-based solv er pr ovides se veral ph ysical mo dels or f eatures tha t are not a vailable with the densit y-based solv er: •Cavitation mo del •Volume-of-fluid ( VOF) mo del •Multiphase mix ture mo del •Euler ian multiphase mo del •Non-pr emix ed c ombustion mo del •Premix ed c ombustion mo del •Partially pr emix ed c ombustion mo del •Comp osition PDF tr ansp ort mo del •Soot mo del •Rosseland r adia tion mo del •Melting/solidific ation mo del Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2560Using the S olver•Shell c onduc tion mo del •Floating op erating pr essur e •Fixed v ariable option •Physical velocity formula tion f or p orous media •Specified mass flo w rate for str eamwise p eriodic flo w The f ollowing f eatures ar e available with the densit y-based solv er, but not with the pr essur e-based solv er: •Wet st eam multiphase mo del For additional inf ormation, see the f ollowing sec tions: 37.1.1. Choosing the S olver 37.1.1. Choosing the S olver To cho ose one of the solv ers, you will use the Gener al Task P age (p.3235 ) (Figur e 37.1: The G ener al Task Page (p.2561 )). Setup → Gener al Figur e 37.1: The G ener al Task P age 2561Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Overview of U sing the S olverTo use the pr essur e-based solv er, retain the default selec tion of Pressur e-Based under Solver. To use the densit y-based solv er, selec t Densit y-Based under Solver. After y ou ha ve defined y our mo del and sp ecified which solv er y ou w ant to use , you ar e ready to run the solv er.The f ollowing st eps outline a gener al pr ocedur e you c an f ollow: 1.(pressur e-based solv er only) S elec t the pr essur e-velocity coupling metho d (see Choosing the P ressur e- Velocity Coupling M etho d (p.2570 )). 2.Choose the spa tial discr etiza tion scheme and , for the pr essur e-based solv er, the pr essur e interpolation scheme (see Choosing the S patial D iscretiza tion Scheme (p.2562 )). 3.(pressur e-based solv er only) S elec t the p orous media v elocity metho d (see Porous M edia C onditions (p.864)). 4.Selec t ho w you w ant the der ivatives to be evalua ted b y cho osing a gr adien t option (see Evalua tion of Gradien ts and D erivatives in the Theor y Guide ). 5.Set the under-r elaxa tion fac tors (see Setting U nder-R elaxa tion F actors (p.2573 )). 6.(densit y-based e xplicit f ormula tion only) S et up the F AS multigr id (see Turning On F AS M ultigr id (p.2587 )). 7.Make an y additional mo dific ations t o the solv er settings tha t are suggest ed in the chapt ers or sec tions that descr ibe the mo dels y ou ar e using . 8.Enable the appr opriate solution monit ors (see Monit oring S olution C onvergenc e (p.2646 )). 9.Initializ e the solution (see Initializing the S olution (p.2604 )). 10.Start calcula ting (see Performing S teady-State Calcula tions (p.2614 ) for st eady-sta te calcula tions , or Perform- ing Time-D ependen t Calcula tions (p.2626 ) for time-dep enden t calcula tions). 11.If you ha ve convergenc e trouble , try one of the metho ds discussed in Convergenc e and S tabilit y (p.2690 ). The default settings f or the first thr ee it ems list ed ab ove ar e suitable f or most pr oblems and need not be changed .The f ollowing sec tions outline ho w these and other solution par amet ers c an b e changed , and when y ou ma y want to change them. 37.2. Choosing the S patial D iscr etiza tion Scheme Gradien ts ar e needed not only f or c onstr ucting v alues of a sc alar a t the c ell fac es, but also f or c omputing secondar y diffusion t erms and v elocity der ivatives. For mor e inf ormation ab out the diff erent gradien ts, see Evalua tion of G radien ts and D erivatives in the Theor y Guide . The thr ee gr adien ts tha t are available in ANSY S Fluen t are •Green-G auss C ell B ased •Green-G auss N ode B ased •Least S quar es C ell B ased The gr adien t options ar e selec table fr om the Gradien t drop-do wn list , in the Solution M etho ds task page . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2562Using the S olverSolution → Metho ds In addition, ANSY S Fluen t allo ws you t o cho ose the discr etiza tion scheme f or the c onvection t erms of each go verning equa tion. (Second-or der accur acy is aut oma tically used f or the visc ous t erms.) By default , single-phase pr oblems using either the pr essur e-based or densit y-based solv er ar e solv ed using sec ond- order up wind discr etiza tion f or the c onvection t erms of the flo w equa tions and all sc alar equa tions except those f or turbulenc e quan tities , which ar e solv ed using first-or der up wind discr etiza tion. For multiphase flo ws, the flo w equa tions use first-or der up wind discr etiza tion b y default. For a c omplet e descr iption of the discr etiza tion schemes a vailable in ANSY S Fluen t, see Discretiza tion in the Theor y Guide . In addition, when y ou use the pr essur e-based solv er, you c an sp ecify the pr essur e in terpolation scheme . For a descr iption of the pr essur e in terpolation schemes a vailable in ANSY S Fluen t, see Pressur e In terpol- ation Schemes in the Theor y Guide . For additional inf ormation, see the f ollowing sec tions: 37.2.1. First-Or der A ccur acy vs. Second-Or der A ccur acy 37.2.2. Other D iscretiza tion Schemes 37.2.3. Choosing the P ressur e Interpolation Scheme 37.2.4. Choosing the D ensit y Interpolation Scheme 37.2.5. High Or der Term Relaxa tion (HO TR) 37.2.6. User Inputs 37.2.1. First-Or der A ccur acy vs. Second-Or der A ccur acy When the flo w is aligned with the mesh (f or e xample , laminar flo w in a r ectangular duc t mo deled with a quadr ilateral or he xahedr al mesh) the first-or der up wind discr etiza tion ma y be acc eptable .When the flow is not aligned with the mesh (tha t is, when it cr osses the mesh lines obliquely), however, first- order c onvective discr etiza tion incr eases the numer ical discr etiza tion er ror (numer ical diffusion). For triangular and t etrahedr al meshes , sinc e the flo w is ne ver aligned with the mesh, you will gener ally obtain mor e accur ate results b y using the sec ond-or der discr etiza tion. For quad/he x meshes , you will also obtain b etter results using the sec ond-or der discr etiza tion, esp ecially f or c omple x flo ws. In summar y, while the first-or der discr etiza tion gener ally yields b etter convergenc e than the sec ond- order scheme , it gener ally will yield less accur ate results , esp ecially on tr i/tet meshes . See Convergenc e and S tabilit y (p.2690 ) for inf ormation ab out c ontrolling c onvergenc e. For most c ases , you will b e able t o use the sec ond-or der scheme fr om the star t of the c alcula tion. In some c ases , however, you ma y need t o star t with the first-or der scheme and then swit ch t o the sec ond- order scheme af ter a f ew it erations . For e xample , if y ou ar e running a high-M ach-numb er flo w calcula tion that has an initial solution much diff erent than the e xpected final solution, you will usually need t o perform a f ew it erations with the first-or der scheme and then tur n on the sec ond-or der scheme and continue the c alcula tion t o convergenc e. Alternatively, full multigr id initializa tion is also a vailable f or some flo w cases tha t allo w you t o pr oceed with the sec ond-or der scheme fr om the star t. For a simple flo w tha t is aligned with the mesh (f or e xample , laminar flo w in a r ectangular duc t mo deled with a quadr ilateral or he xahedr al mesh), the numer ical diffusion will b e na turally lo w, so y ou c an gener ally use the first-or der scheme inst ead of the sec ond-or der scheme without an y signific ant loss of accur acy. Finally , if y ou r un in to convergenc e difficulties with the sec ond-or der scheme , you should tr y the first- order scheme inst ead. 2563Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Choosing the S patial D iscretiza tion Scheme37.2.1.1. First- t o Higher -Order Blending While the higher-or der scheme ma y result in gr eater accur acy, it c an also r esult in c onvergenc e diffi- culties and instabilities a t certain flo w conditions . On the other hand , using a first-or der scheme ma y not pr ovide the desir ed accur acy. One appr oach t o achie ving impr oved accur acy while main taining good stabilit y is t o use a discr etiza tion blending fac tor.This f eature is a vailable f or b oth densit y-based and pr essur e-based solv ers and c an b e invoked using the f ollowing t ext command: solve → set → numerics Enter a v alue b etween 0 and 1 when ask ed f or the blending fac tor:1st-order to higher-order blending factor [min=0.0 - max=1.0] A blending fac tor of 0 reduc es the gr adien t reconstr uction t o a first-or der discr etiza tion scheme , wher eas 1 will r ecover high-or der discr etiza tion. A blending fac tor of less than 1 (typic ally 0.75 or 0.5) will mak e the c onvective flux es mor e diffusiv e, which in some flo w conditions c an stabiliz e a solution tha t is other wise unstable when the full higher-or der discr etiza tion scheme is emplo yed. Imp ortant Note tha t in or der t o use this f eature eff ectively, mak e sur e tha t one of the allo wed higher- order discr etiza tion schemes is selec ted f or the desir ed v ariables in the Solution M etho ds task page . 37.2.2. Other D iscr etiza tion Schemes The QUICK and thir d-or der MUSCL discr etiza tion schemes ma y pr ovide b etter accur acy than the sec ond- order scheme f or rotating or swir ling flo ws.The QUICK scheme is applic able t o quadr ilateral or he xa- hedr al meshes , while the MUSCL scheme is used on all t ypes of meshes . In gener al, however, the second-or der scheme is sufficien t and the QUICK scheme will not pr ovide signific ant impr ovemen ts in accur acy. Imp ortant If QUICK is used f or h ybrid meshes , it will b e used only f or quadr ilateral and he xahedr al cells. Second-or der up wind discr etiza tion will b e applied t o all other c ells. The b ounded c entral diff erencing and (f or the pr essur e-based solv er) c entral diff erencing schemes ar e available when y ou ar e using the LES, DES, SAS, SBES, and SDES turbulenc e mo dels , and the c entral differencing scheme should b e used only when the mesh spacing is fine enough so tha t the magnitude of the lo cal Peclet numb er (see Equa tion 28.6 in the Theor y Guide ) is less than 1. A mo dified HRIC scheme (see Modified HRIC Scheme in the Theor y Guide ) is also a vailable f or VOF simula tions using either the implicit or e xplicit f ormula tion. 37.2.3. Choosing the P ressur e In terpolation Scheme As discussed in Pressur e In terpolation Schemes in the Theor y Guide , a numb er of pr essur e in terpolation schemes ar e available when the pr essur e-based solv er is used in ANSY S Fluen t. For most c ases the second-or der scheme is acc eptable , but some t ypes of mo dels ma y benefit fr om one of the other schemes: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2564Using the S olver•For mix ture or VOF multiphase mo dels , either the PREST O! or b ody-force-weigh ted schemes should b e used and only these schemes ar e made a vailable .The default in these c ases is PREST O!. •For E uler ian multiphase mo dels , the default scheme is PREST O!. However, for multi-fluid VOF pr oblems that use the non-it erative solv er, the Second Or der interpolation scheme c an b e mor e robust f or cases with sk ewed meshes , and the Body Force Weigh ted interpolation scheme c an b e mor e robust f or cases with lar ge b ody forces and sk ewed meshes . •For pr oblems in volving lar ge b ody forces, the b ody-force-weigh ted scheme is r ecommended . •For flo ws with high swir l numb ers, high-R ayleigh-numb er na tural convection, high-sp eed r otating flo ws, and flo ws in str ongly cur ved domains , use the PREST O! scheme . 37.2.4. Choosing the D ensit y In terpolation Scheme As discussed in Densit y Interpolation Schemes in the Theor y Guide , four densit y interpolation schemes are available when the pr essur e-based solv er is used t o solv e a single-phase c ompr essible flo w. The sec ond-or der up wind scheme (the default) pr ovides r easonable stabilit y for the discr etiza tion of the pr essur e-correction equa tion, and giv es go od results f or most classes of flo ws.The first-or der up wind scheme will pr ovide gr eater stabilit y, but ma y tend t o smo oth sho cks in c ompr essible flo ws. If you ar e calcula ting a c ompr essible flo w with sho cks y ou should use the sec ond-or der-up wind or QUICK scheme . Using the QUICK scheme f or all v ariables , including densit y, is highly r ecommended f or c ompr essible flows with sho cks when using quadr ilateral, hexahedr al, or h ybrid meshes .The thir d-or der MUSCL scheme is applic able t o arbitr ary meshes and has the p otential t o impr ove spa tial accur acy for all t ypes of meshes b y reducing numer ical diffusion. Imp ortant In the c ase of multiphase flo ws, the selec ted densit y scheme is applied t o the c ompr essible phase and ar ithmetic a veraging is used f or inc ompr essible phases . 37.2.5. High Or der Term Relaxa tion (HO TR) The pur pose of the r elaxa tion of high or der t erms is t o impr ove the star tup and the gener al solution behavior of flo w simula tions when higher or der spa tial discr etiza tions ar e used (higher than first). It has also sho wn t o pr event convergenc e stalling in some c ases . Such high-or der t erms c an b e of signi- ficant imp ortanc e in c ertain c ases and lead t o numer ical instabilities .This is par ticular ly tr ue a t aggr essiv e solution settings . In such c ases , high or der r elaxa tion is a useful str ategy to minimiz e your in teraction during the solution. This c an b e an eff ective alt ernative to star ting the solution first or der, then swit ching t o sec ond or der spa tial discr etiza tion a t a la ter stage . The High Or der Term Relaxa tion option c an b e enabled fr om the Solution M etho ds task page , as shown in Figur e 37.2: The S olution M etho ds Task P age f or the HO TR Option (p.2566 ). Solution → Metho ds 2565Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Choosing the S patial D iscretiza tion SchemeFigur e 37.2: The S olution M etho ds Task P age f or the HO TR Option Further c ontrol of High Or der Term Relaxa tion can b e obtained af ter click ing Options ... and mak ing the nec essar y selec tions and settings in the Relaxa tion Options dialo g box (Figur e 37.3: The R elaxa tion Options D ialog Box (p.2567 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2566Using the S olverFigur e 37.3: The Relaxa tion Options D ialo g Box You ha ve the option of selec ting All Variables to be under-r elax ed inst ead of only the default flo w variables ( Flow Variables Only ). •If you selec t Flow Variables Only , then the f ollowing v ariables will b e under-r elax ed: –Velocity comp onen ts –Pressur e –Ener gy –Densit y –Turbulenc e quan tities (e xcluding R eynolds str esses) –Volume fr action •If you selec t All Variables , then r elaxa tion is applied t o each v ariable discr etized with a higher or der scheme . The default v alues f or the Relaxa tion F actor is 0.25 f or st eady-sta te cases and 0.75 f or tr ansien t cases . The same fac tor is applied t o all equa tions solv ed. For theor etical inf ormation ab out high or der t erm relaxa tion, see High Or der Term R elaxa tion in the Theor y Guide . 37.2.5.1. Limitations The f ollowing limita tions e xist when using the High Or der Term Relaxa tion option: •The High Or der Term Relaxa tion option is not a vailable when the Non-I terative Time A dvanc emen t option is enabled , sinc e the simula tion w ould not achie ve the r equir ed le vel of high or der spa tial accur acy. •In gener al, high or der t erm relaxa tion is a vailable f or tr ansien t flo ws. Nevertheless , it should b e used with c are.To achie ve high or der accur acy at convergenc e for each time st ep, you must incr ease the numb er of it erations p er time st ep t o ensur e tha t the or iginal c onvergenc e criteria ha ve been met. 2567Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Choosing the S patial D iscretiza tion Scheme•When the QUICK scheme is selec ted f or sp ecific tr ansp ort equa tions , no under-r elaxa tion is applied to this equa tion. 37.2.6. User Inputs You c an sp ecify the discr etiza tion scheme and , for the pr essur e-based solv er, the pr essur e in terpolation scheme in the Solution M etho ds Task P age (p.3603 ) (Figur e 37.4: The S olution M etho ds Task P age f or the P ressur e-Based S egregated A lgor ithm (p.2568 )). Solution → Metho ds Figur e 37.4: The S olution M etho ds Task P age f or the P ressur e-Based S egrega ted A lgor ithm Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2568Using the S olverFor each sc alar equa tion list ed under Spatial D iscr etiza tion (Momen tum ,Energy,Turbulen t Kinetic Energy, and so on, for the pr essur e-based solv er or Turbulen t Kinetic E nergy,Turbulen t Dissipa tion Rate, and so on, for the densit y-based solv er) y ou c an cho ose First Or der U pwind ,Second Or der Upwind ,QUICK ,Third-Or der MUSCL , or (f or Momen tum when y ou ar e using the LES, DES, SAS, SDES, or SBES turbulenc e mo del) Bounded C entral D ifferencing (the default) or Central D ifferencing in the adjac ent drop-do wn list. For the densit y-based solv er, you c an cho ose either First Or der U pwind , Second Or der U pwind ,Third-Or der MUSCL , or (when y ou ar e using the LES, DES, SAS, SDES, or SBES turbulenc e mo del) Bounded C entral D ifferencing for the Flow equa tions (which include momen tum and ener gy). Note tha t the task page sho wn in Figur e 37.4: The S olution M etho ds Task P age f or the Pressur e-Based S egregated A lgor ithm (p.2568 ) is for the pr essur e-based solv er. If you ar e using the pr essur e-based solv er, selec t the pr essur e in terpolation scheme under Spatial Discr etiza tion , in the dr op-do wn list ne xt to Pressur e.You c an cho ose Standar d,PREST O!,Linear , Second Or der, or Body Force Weigh ted. Imp ortant The lo w-or der f ormula tion of PREST O! c an b e applied b y limiting the high-or der t erms f or the PREST O! scheme .This is done using the f ollowing t ext command: solve → set → numerics When ask ed limit high-order terms for PRESTO! pressure scheme? , enter yes . This mo dific ation c an b e used t o stabiliz e the solution pr ocess when the pr essur e-based coupled algor ithm is used and when the or iginal PREST O! scheme either fails t o converge or pr oduces unph ysical oscilla tions (wiggles) in the pr essur e field . If you ar e using the pr essur e-based solv er and y our flo w is c ompr essible (tha t is, you ar e using the ideal gas la w for densit y), selec t the densit y interpolation scheme under Spatial D iscr etiza tion , in the drop-do wn list ne xt to Densit y.You c an cho ose First Or der U pwind ,Second Or der U pwind ,QUICK or Third-Or der MUSCL . (Note tha t Densit y will not app ear f or inc ompr essible flo ws.) If you enable the VOF mo del while using the pr essur e-based solv er, the v olume fr action in terpolation schemes tha t are available ar e Geo-Rec onstr uct,CICSAM ,Modified HRIC , and QUICK . If your c ase in volves sp ecies tr ansp ort, you c an set the scheme f or the individual sp ecies as First Or der Upwind ,Second Or der U pwind ,QUICK , or Third-Or der MUSCL . However, if y ou w ant all y our sp ecies to use the same discr etiza tion scheme , then r ather than setting each one individually , simply enable the Set A ll Species D iscr etiza tions Together option. Notice tha t you will no longer see y our list of individual sp ecies , inst ead a Species field will app ear with the scheme of y our choic e. If you change the settings f or the Spatial D iscr etiza tion , but y ou then w ant to retur n to ANSY S Fluen t’s default settings , you c an click the Default butt on. Imp ortant If your mesh t opology has st ep-wise pr ism mesh near the w alls, do not use no de-based gradien ts with MUSCL. 2569Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Choosing the S patial D iscretiza tion Scheme37.3. Pressur e-Based S olver S ettings For additional inf ormation, see the f ollowing sec tions: 37.3.1. Choosing the P ressur e-Velocity Coupling M etho d 37.3.2. Setting U nder-R elaxa tion F actors 37.3.3. Setting S olution C ontrols f or the N on-I terative Solver 37.3.4. Equa tion Or der 37.3.1. Choosing the P ressur e-Velocity Coupling M etho d The pr essur e-velocity coupling scheme c ontrols the manner in which pr essur e and v elocity are up dated when the pr essur e-based solv er is used .The scheme c an b e either segr egated (pr essur e and v elocity are up dated sequen tially) or c oupled (pr essur e and v elocity are up dated simultaneously). ANSY S Fluen t provides the f ollowing segr egated t ypes of algor ithms: •SIMPLE •SIMPLEC •PISO •Fractional S tep (FSM) (time-dep enden t flo ws with Non-I terative Time A dvanc emen t (NIT A) only) In gener al, segr egated metho ds ar e fast er p er it eration, while the c oupled algor ithm usually r equir es fewer it erations t o converge. For this r eason, the c oupled solv er is usually r ecommended f or st eady- state simula tions . For tr ansien t simula tions , the c oupled solv er has the b est r obustness pr operties, es- pecially f or lar ge time st ep siz es, but SIMPLEC, PISO , or NIT A ma y giv e fast er o verall solution times f or small time st ep siz es. The c oupled solv er off ers the f ollowing mechanisms t o under-r elax the equa tions: •Pseudo Transien t (st eady-sta te only) •Courant numb er Coupled pseudo-tr ansien t is the default selec tion f or c ases with the f ollowing settings: •Steady-sta te •Single-phase •No ba ttery or fuel c ell mo del •No solidific ation and melting mo del Controls f or the c oupled pseudo-tr ansien t solv er ar e descr ibed in Performing P seudo Transien t Calcu- lations (p.2617 ).The most imp ortant (and t ypic ally the only) c ontrol you need t o adjust in pr actice is the Pseudo Time S tep, as descr ibed in Solving P seudo-T ransien t Flow (p.2622 ). Imp ortant Pressur e-velocity coupling is r elevant only f or the pr essur e-based solv er. 37.3.1.1. SIMPLE v s. SIMPLEC In ANSY S Fluen t, both the standar d SIMPLE algor ithm and the SIMPLEC (SIMPLE-C onsist ent) algor ithm are available . SIMPLE is the default , but man y pr oblems will b enefit fr om using SIMPLEC, par ticular ly because of the incr eased under-r elaxa tion tha t can b e applied , as descr ibed b elow. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2570Using the S olverFor relatively unc omplic ated pr oblems (laminar flo ws with no additional mo dels enabled) in which convergenc e is limit ed b y the pr essur e-velocity coupling , you c an of ten obtain a c onverged solution mor e quick ly using SIMPLEC. With SIMPLEC, the pr essur e-correction under-r elaxa tion fac tor is gener ally set t o 1.0, which aids in c onvergenc e sp eed-up . In some pr oblems , however, incr easing the pr essur e- correction under-r elaxa tion t o 1.0 c an lead t o instabilit y due t o high mesh sk ewness . For such c ases , you will need t o use one or mor e sk ewness c orrection schemes , use a sligh tly mor e conser vative under- relaxa tion v alue (up t o 0.7), or use the SIMPLE algor ithm. For c omplic ated flo ws involving turbulenc e and/or additional ph ysical mo dels , SIMPLEC will impr ove convergenc e only if it is b eing limit ed b y the pr essur e-velocity coupling . Often it will b e one of the additional mo deling par amet ers tha t limits convergenc e; in this c ase, SIMPLE and SIMPLEC will giv e similar c onvergenc e rates. 37.3.1.2. PISO The PISO algor ithm (see PISO in the Theor y Guide ) with neighb or c orrection is highly r ecommended for all tr ansien t flo w calcula tions , esp ecially when y ou w ant to use a lar ge time st ep. (For pr oblems that use the LES turbulenc e mo del, which usually r equir es small time st eps, using PISO ma y result in an incr eased c omputa tional e xpense , so SIMPLE or SIMPLEC should b e consider ed inst ead.) PISO c an main tain a stable c alcula tion with a lar ger time st ep and an under-r elaxa tion fac tor of 1.0 f or b oth momen tum and pr essur e. For st eady-sta te pr oblems , PISO with neighb or c orrection do es not pr ovide any notic eable ad vantage o ver SIMPLE or SIMPLEC with optimal under-r elaxa tion fac tors. PISO with sk ewness c orrection is r ecommended f or b oth st eady-sta te and tr ansien t calcula tions on meshes with a high degr ee of dist ortion. When y ou use PISO neighb or c orrection, under-r elaxa tion fac tors of 1.0 or near 1.0 ar e recommended for all equa tions . If you use just the PISO sk ewness c orrection f or highly-dist orted meshes (without neighb or c orrection), set the under-r elaxa tion fac tors f or momen tum and pr essur e so tha t the y sum to 1 (f or e xample , 0.3 f or pr essur e and 0.7 f or momen tum). If you use b oth PISO metho ds, follow the under-r elaxa tion r ecommenda tions f or PISO neighb or c orrection, above. For most pr oblems , it is not nec essar y to disable the default c oupling b etween neighb or and sk ewness corrections . For highly dist orted meshes , however, disabling the default c oupling b etween neighb or and sk ewness c orrections is r ecommended . 37.3.1.3. Fractional St ep Metho d The F ractional S tep metho d (FSM), descr ibed in Fractional-S tep M etho d (FSM) in the Theor y Guide , is available when y ou cho ose t o use the NIT A scheme (tha t is, the Non-I terative Time A dvanc emen t option in the Solution M etho ds task page). With the NIT A scheme , the FSM is sligh tly less c omputa- tionally e xpensiv e compar ed t o the PISO algor ithm. Whether y ou selec t FSM or PISO dep ends on the applic ation. For some pr oblems (f or e xample , simula tions tha t use VOF), FSM c ould b e less stable than PISO . In most c ases , the default v alues f or the solution metho ds ar e enough t o set a r obust c onvergenc e of the in ternal pr essur e correction sub-it erations due t o sk ewness . Only v ery comple x pr oblems (f or example , mo ving def orming meshes , sliding in terfaces, the VOF mo del) c ould r equir e a r educ tion of relaxa tion f or pr essur e up t o a v alue of 0.7 or 0.8. 37.3.1.4. Coupled Selec ting Coupled from the Pressur e-Velocity Coupling drop-do wn list indic ates tha t you ar e using the pr essur e-based c oupled algor ithm, descr ibed in Coupled A lgor ithm in the Theor y Guide .This 2571Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Pressur e-Based S olver Settingssolv er off ers some ad vantages o ver the pr essur e-based segr egated algor ithm. The pr essur e-based coupled algor ithm obtains a mor e robust and efficien t single phase implemen tation f or st eady-sta te flows. It is not a vailable f or c ases using the Non-I terative Time A dvanc emen t option (NIT A). Note In some c ases using p orous jump b oundar y conditions , the Coupled scheme ma y suff er from c onvergenc e issues tha t do not r espond t o changes in the c oupled solv er settings . This b ehavior dep ends on the sp ecific flo w configur ation and p orous jump b oundar y condition v alues . If convergenc e instabilit y is obser ved in c ases using p orous jump boundar y conditions and the Coupled scheme , it is r ecommended tha t you change the pressur e-velocity coupling t o one of the segr egated schemes . 37.3.1.5. User Inputs You c an sp ecify the pr essur e-velocity coupling metho d in the Solution M etho ds Task P age (p.3603 ) (Figur e 37.4: The S olution M etho ds Task P age f or the P ressur e-Based S egregated A lgor ithm (p.2568 )). Solution → Metho ds Choose SIMPLE ,SIMPLEC ,PISO ,Fractional S tep, or Coupled in the Pressur e-Velocity Coupling drop-do wn list. If you cho ose PISO , the task page will e xpand t o sho w the additional par amet ers f or pr essur e-velocity coupling . By default , the numb er of it erations f or Skewness C orrection and Neighb or C orrection are set t o 1. If you w ant to use only Skewness C orrection , then set the numb er of it erations f or Neighb or C orrection to 0. Likewise , if y ou w ant to use only Neighb or C orrection , then set the numb er of it erations f or Skewness C orrection to 0. For most pr oblems , you do not need t o change the default it eration v alues . By default , the Skewness-N eighb or C oupling option is enabled t o allo w for a mor e ec onomic al, but a less r obust v ariation of the PISO algor ithm. If you cho ose SIMPLEC under Pressur e-Velocity Coupling , you must also set the Skewness C orrec- tion , whose default v alue is 0. If you cho ose Coupled without the Pseudo Transien t option, you will ha ve to sp ecify the Cour ant numb er in the Solution C ontrols task page , which is set a t 200 by default. You will also sp ecify the Explicit Relaxa tion F actors for Momen tum and Pressur e, which ar e set a t 0.5 by default. For mor e information ab out these options , refer to Pressur e-Velocity Coupling and Steady-State Iterative Al- gorithm in the Theor y Guide . For c ases with v ery sk ewed meshes , the r un c an b e stabiliz ed b y fur ther r educ tion of the e xplicit r e- laxa tion fac tor to 0.25 . If ANSY S Fluen t immedia tely div erges in the AMG solv er, then the CFL numb er is too high and should b e reduc ed. Reducing the CFL numb er b elow 10 is not r ecommended sinc e it w ould b e better to use the segr egated algor ithm f or the pr essur e-velocity coupling . In most tr ansien t cases , the CFL numb er should b e set t o a lar ge v alue such as 107 and e xplicit r elax- ation fac tors t o 1.0. If you cho ose Coupled and enable the Pseudo Transien t option, you will set the Pseudo Transien t Explicit Relaxa tion F actors in the Solution C ontrols task page , as descr ibed in Setting P seudo Transien t Explicit R elaxa tion F actors (p.2619 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2572Using the S olver37.3.2. Setting U nder-Relaxa tion F actors The pr essur e-based solv er uses under-r elaxa tion of equa tions t o control the up date of c omput ed variables a t each it eration (as descr ibed in Under-R elaxa tion of E qua tions in the Theor y Guide ).This means tha t all equa tions solv ed using the pr essur e-based solv er,including the non-c oupled equations solved b y the densit y-based sol ver (turbulenc e and other sc alars , as discussed in Densit y-Based S olver in the Theor y Guide ), will ha ve under-r elaxa tion fac tors asso ciated with them. In ANSY S Fluen t, the default under-r elaxa tion par amet ers f or all v ariables ar e set t o values tha t are near optimal f or the lar gest p ossible numb er of c ases .These v alues ar e suitable f or man y pr oblems , but f or some par ticular ly nonlinear pr oblems (f or e xample , some turbulen t flo ws or high-R ayleigh- numb er na tural-convection pr oblems) it is pr uden t to reduc e the under-r elaxa tion fac tors initially . It is go od pr actice to begin a c alcula tion using the default under-r elaxa tion fac tors. If the r esiduals continue t o incr ease af ter the first 4 or 5 it erations , you should r educ e the under-r elaxa tion fac tors. Occasionally , you ma y mak e changes in the under-r elaxa tion fac tors and r esume y our c alcula tion, only to find tha t the r esiduals b egin t o incr ease .This of ten r esults fr om incr easing the under-r elaxa tion factors t oo much. A c autious appr oach is t o sa ve a da ta file b efore mak ing an y changes t o the under- relaxa tion fac tors, and t o giv e the solution algor ithm a f ew it erations t o adjust t o the new par amet ers. Typic ally, an incr ease in the under-r elaxa tion fac tors br ings ab out a sligh t incr ease in the r esiduals , but these incr eases usually disapp ear as the solution pr ogresses . If the r esiduals jump b y a f ew or ders of magnitude , you should c onsider halting the c alcula tion and r etur ning t o the last go od da ta file sa ved. Note tha t visc osity and densit y are under-r elax ed fr om it eration t o iteration. Also, if the en thalp y equa tion is solv ed dir ectly inst ead of the t emp erature equa tion (tha t is, for non-pr emix ed c ombustion calcula tions), the up date of t emp erature based on en thalp y will b e under-r elax ed.To see the default under-r elaxa tion fac tors, you c an click the Default butt on in the Solution C ontrols Task P age (p.3606 ). For most flo ws, the default under-r elaxa tion fac tors do not usually r equir e mo dific ation. If unstable or divergen t behavior is obser ved, however, you need t o reduc e the under-r elaxa tion fac tors f or pr essur e, momen tum, , and from their default v alues t o ab out 0.2, 0.5, 0.5, and 0.5. (It is usually not nec essar y to reduc e the pr essur e under-r elaxa tion f or SIMPLEC.) In pr oblems wher e densit y is str ongly c oupled with t emp erature, as in v ery-high-R ayleigh-numb er na tural- or mix ed-c onvection flo ws, it is wise t o also under-r elax the t emp erature equa tion and/or densit y (tha t is, use an under-r elaxa tion fac tor less than 1.0). Conversely , when t emp erature is not c oupled with the momen tum equa tions (or when it is weakly coupled), as in flo ws with c onstan t densit y, the under-r elaxa tion fac tor for temp erature can b e set t o 1.0. For other sc alar equa tions (f or e xample , swir l, species , mix ture fraction and v arianc e) the default under- relaxa tion ma y be too aggr essiv e for some pr oblems , esp ecially a t the star t of the c alcula tion. You ma y want to reduc e the fac tors t o 0.8 t o facilita te convergenc e. 37.3.2.1. User Inputs You c an mo dify the under-r elaxa tion fac tors in the Solution C ontrols Task P age (p.3606 ) (Figur e 37.5: The Solution C ontrols Task P age f or the P ressur e-Based S olver (p.2574 )). Solution → Controls 2573Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Pressur e-Based S olver SettingsFigur e 37.5: The S olution C ontrols Task P age f or the P ressur e-Based S olver You c an set the under-r elaxa tion fac tor for each equa tion in the field ne xt to its name under Under- Relaxa tion F actors. Imp ortant If you ar e using the pr essur e-based solv er, all equa tions will ha ve an asso ciated under-r e- laxa tion fac tor (see Under-R elaxa tion of E qua tions in the Theor y Guide ). If you ar e using the densit y-based solv er, only those equa tions tha t are solv ed sequen tially (see Densit y- Based S olver in the Theor y Guide ) will ha ve under-r elaxa tion fac tors. If your c ase in volves sp ecies tr ansp ort, you c an set the under-r elaxa tion fac tors f or each of the list ed species . If you w ant all y our sp ecies t o use the same under-r elaxa tion fac tors, simply enable the Set All Species URFs Together option. Notice tha t you will no longer see y our list of individual sp ecies , instead a Species field will app ear wher e you will sp ecify the under-r elaxa tion fac tor. If you change under-r elaxa tion fac tors, but y ou then w ant to retur n to ANSY S Fluen t’s default settings , you c an click the Default butt on. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2574Using the S olverNote tha t with optimal settings , the c onvergenc e of the c oupled pr essur e-velocity algor ithm will b e limit ed b y the segr egated solution of other sc alar equa tions , for e xample , turbulenc e. For optimum solv er p erformanc e, you will need t o incr ease the r elaxa tion fac tors f or these equa tions t o a v alue greater than the default v alues . 37.3.3. Setting S olution C ontrols f or the N on-I terative Solver You c an use the non-it erative solv er (see Time-A dvancemen t Algor ithm in the Theor y Guide ) for tr an- sien t problems in or der t o incr ease the sp eed and efficienc y of the c alcula tions .You c an also obtain a steady solution using the non-it erative multiphase solv er for multiphase flo ws with quasi-st eady conditions . To control the change of c omput ed v ariables a t each it eration, you c an sp ecify e xplicit r elaxa tion in the Non-I terative Solver Relaxa tion F actors list in the Solution C ontrols Task P age (p.3606 ). Additional information on r elaxa tion fac tors c an b e found in Setting U nder-R elaxa tion F actors (p.2573 ). Other solution c ontrols ar e acc essible via the Expert tab , in the Advanc ed S olution C ontrols dialo g box (see Figur e 37.6: The A dvanced S olution C ontrols D ialog Box for the P ressur e-Based S egregated Non-I terative Solver (p.2577 )).The cr iteria for c onvergenc e include the Correction Toler anc e (defined by the o verall accur acy),Residual Toler anc e (controlling the solution of the linear equa tions), and Max. Corrections (controlling the maximum numb er of sub-it erations f or each individual equa tion). The default c ontrol settings ar e optimally designed in or der t o get a sec ond-or der accur ate solution. To use ANSY S Fluen t’s non-it erative transien t solv er in or der t o boost the efficienc y of tr ansien t simu- lations: 1.Go to the Solution M etho ds task page . Solution → Metho ds 2.Make sur e tha t Coupled is not selec ted fr om the Pressur e-Velocity Coupling drop-do wn list. 3.Enable Non-I terative Time A dvanc emen t. 4.Under Pressur e-Velocity Coupling , selec t a scheme fr om the dr op-do wn list: •For single phase or VOF multiphase flo ws:You c an selec t either the Fractional S tep or PISO scheme . For the PISO scheme , you c an set the v alue f or the Neighb or C orrection . Skewness c orrection is p er- formed aut oma tically. •For E uler ian multiphase flo ws: Selec t the Phase C oupled SIMPLE .This is the only pr essur e scheme available f or NIT A multiphase simula tions . 5.When using the Lar ge E ddy Simula tion (LES) turbulenc e mo del, you c an enable the Acceler ated Time M arching option in or der t o sp eed up the simula tion. This option is in tended f or unr eacting flow simula tions tha t use a c onstan t-densit y fluid . It enables a mo dified NIT A scheme and changes the f ollowing t o a mor e aggr essiv e setting: •The maximum numb er of sub-it erations f or the NIT A solv er equa tions (sp ecified in the Expert tab of the Advanc ed S olution C ontrols dialo g box) ar e revised: the Max. Corrections is set t o 0 for Pressur e and 1 for all other equa tions . •The pr essur e-velocity coupling scheme (sp ecified in the Solution M etho ds task page) is changed t o the Fractional S tep metho d. 2575Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Pressur e-Based S olver Settings•The multigr id solv er settings (sp ecified in the Multigr id tab of the Advanc ed S olution C ontrols dialo g box) ar e revised: for the Pressur e equa tion, the Cycle Type is changed t o F-Cycle and the Termina tion criterion is set t o 0.01 . Note The f ollowing limita tions / r ecommenda tions apply : •The acc elerated time mar ching option is not a vailable with the E uler ian multiphase mo del. •It is not r ecommended f or compr essible or v ariable-densit y fluids . •When using this option, it is r ecommended tha t you use the Bounded C entral D ifferencing scheme f or the Momen tum equa tion r ather than the Central D ifferencing scheme . 37.3.3.1. User Inputs You c an mo dify the under-r elaxa tion fac tors in the Solution C ontrols Task P age (p.3606 ) (Figur e 37.5: The Solution C ontrols Task P age f or the P ressur e-Based S olver (p.2574 )). Solution → Controls The r elaxa tion fac tors define the e xplicit r elaxa tion (see Under-R elaxa tion of Variables in the Theor y Guide ) of v ariables b etween sub-it erations .The r elaxa tion fac tors c an b e used t o pr event the solution from div erging . If the solution is unstable: •For single phase flo ws:You should first tr y to stabiliz e the solution b y lowering the r elaxa tion fac tors f or pressur e to 0.7–0.8, and b y reducing the time st ep. •For multiphase flo ws: Consider lo wering the e xplicit pr essur e relaxa tion fac tor up t o 0.5. This ma y help when meshes ar e poor, because a p oor mesh will signific antly aff ect the pr essur e gr adien t, which in tur n may gener ate lar ge sour ce terms in the go verning equa tions r esulting in p oor convergenc e.You c an set the under-r elaxa tion fac tors f or the other flo w variables t o higher v alues (0.8-1.0). For compr essible mul- tiphase flo w, you c an use e xplicit r elaxa tion of densit y in the r ange 0.5-0.8. For multiphase c ases with mass tr ansf er, you c an use e xplicit r elaxa tion of v aporization mass in the r ange 0.5-0.8. You c an mo dify the non-it erative solution c ontrols in the Advanced S olution C ontrols D ialog Box (p.3611 ) (Figur e 37.6: The A dvanced S olution C ontrols D ialog Box for the P ressur e-Based S egregated N on-I ter- ative Solver (p.2577 )). Solution → Controls → Advanc ed... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2576Using the S olverFigur e 37.6: The A dvanc ed S olution C ontrols D ialo g Box for the P ressur e-Based S egrega ted Non-I terative Solver Under Non-I terative Solver C ontrols, ther e ar e se veral par amet ers tha t control the sub-it erations for the individual equa tions . The sub-it erations f or an equa tion st op when the t otal numb er of sub-it erations e xceeds the v alue specified f or Max. Corrections , regar dless of whether or not the c onvergenc e cr iteria (descr ibed b elow) are met. The sub-it erations f or an equa tion end when the r atio of the r esiduals a t the cur rent sub-it eration and the first sub-it eration is less than the v alue sp ecified in the Correction Toler anc e field .You c an monit or the details of the sub-it eration c onvergenc e by looking a t the AMG solv er p erformanc e (tha t is, setting the Verb osit y field in the Multigr id tab in the Advanc ed S olution C ontrols dialo g box to 1). Be sur e to pa y attention t o the r esiduals f or the cur rent sub-it eration (tha t is, the r esidual f or the 0-th AMG c ycle a t the cur rent sub-it eration) and the initial r esidual of the time st ep (tha t is, the residual f or the 0-th AMG c ycle of the first sub-it eration). The r atio of these t wo residuals is wha t is controlled b y the Correction Toler anc e field .These t wo residuals ar e also the r esiduals plott ed when using the Residual M onit or panel and r eported in the ANSY S Fluen t console a t the end of a time step. Note tha t the r esiduals r eported a t the end of a time st ep c an b e sc aled or unsc aled , dep ending 2577Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Pressur e-Based S olver Settingson the settings in the Residual M onit or dialo g box.The r esiduals r eported when monit oring the AMG solv er p erformanc e ar e alw ays unsc aled . For each in terim sub-it eration, the AMG c ycles c ontinue un til the usual AMG t ermina tion cr iteria (0.1 by default , and set in the Multigr id tab) ar e met. However, for the last sub-it eration (tha t is, either when the maximum numb er of sub-it erations ar e reached or when the c orrection t oler ance is sa tisfied), the AMG c ycles c ontinue un til the r atio of the r esidual a t the cur rent cycle t o the initial r esidual (the residual f or the 0-th AMG c ycle of the first sub-it eration of the time st ep) dr ops b elow the v alue specified f or Residual Toler anc e.You ma y want to adjust the Residual Toler anc e, dep ending on the time st ep selec ted.The default Residual Toler anc e should b e well suit ed f or mo derate time st eps (tha t is, for c ell CFL numb ers of 1 t o 10). Note tha t you c an displa y the c ell CFL numb ers f or unst eady problems b y selec ting Cell C our ant Numb er in the Velocity... categor y of all p ostpr ocessing dialo g boxes. For v ery small time st eps (c ell CFL <<1), the diagonal dominanc e of the sy stem is v ery high and the c onvergenc e should b e dr iven fur ther b y reducing the Residual Toler anc e value . For lar ger time st eps (c ell CFL >>1), it ma y be possible tha t the r esidual t oler ance cannot b e reached due t o round-off er rors, and unless the Residual Toler anc e value is incr eased , AMG c ycles c an b e wasted. Again, this c an b e monit ored b y monit oring the AMG solv er p erformanc e. 37.3.3.2. NIT A Expert Options •To obtain diagnostics on c onvergenc e of sub-it erations f or individual equa tions , use the f ollowing t ext command: solve/set/nita-expert-controls/set-verbosity verbosity [0] 1 The output inf ormation ma y help y ou t o judge whether the sp ecified numb er of sub-it erations is sufficien t to reach the c orrection t oler ance and also t o diagnose the sour ce of the solution div er- genc e. •For NIT A cases with PISO selec ted as a Pressur e-Velocity Coupling scheme , you c an enable c oupling of the neighb or and sk ewness c orrections with the f ollowing TUI c ommand: solve/set/nita-expert-controls/skewness-neighbor-coupling enable skewness neighbor coupling for nita [no] yes For mor e inf ormation ab out this option, see Skewness - N eighb or C oupling in the Fluent Theor y Guide . •For NIT A cases tha t involve VOF, hybrid NIT A expert options ma y help y ou t o impr ove solution r obustness , but a t the c ost of sp eed. Depending on y our c ase, the h ybrid NIT A expert settings ma y optimiz e NIT A expert controls, explicit r elaxa tion fac tors, and out er it erations .To use the h ybrid NIT A expert options , enter the f ollowing t ext commands: solve/set/nita-expert-controls/hybrid-nita-settings enable hybrid nita settings? [no] yes You c an selec t from the f ollowing options: –0: Recommended f or inc ompr essible and N ewtonian (lo w visc osity ratio) flo w. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2578Using the S olver–1: Recommended f or compr essible and N ewtonian (lo w visc osity ratio) flo w and hea t/mass-tr ansf er. –2: Recommended f or non-N ewtonian or high visc osity ratio flo w.You c an also use this option when ther e is a str ong equa tion c oupling , and the ab ove options do not pr oduce useful r esults . In case of div ergenc e when using NIT A, the f ollowing settings ma y help: –Switch to a diff erent pressur e spa tial discr etiza tion scheme (fr om PREST O! to Body Force Weigh ted or vic e versa). –Reduc e Explicit Relaxa tion F actors for pr essur e, momen tum and v olume fr action do wn t o 0.6. Note Currently, the r esidual r eports displa y two residuals f or each out er it eration. 37.3.3.3. Compatibilit y of the NIT A Scheme with O ther ANSY S Fluent Mo dels The f ollowing is a list of mo dels tha t are compa tible with the non-it erative solv er: •Inviscid flo w (e xcluding ideal gas) •Laminar flo w •All mo dels of turbulenc e (including LES and DES) •S2S r adia tion mo del •Heat transf er •Non-r eacting sp ecies tr ansp ort •Gener al compr essible flo ws (most subsonic and some tr ansonic applic ations) •VOF multiphase mo del (most applic ations) •Euler ian multiphase mo del •Phase change (solidific ation and melting) •Porous media mo del (isotr opic r esistanc e) •Multiphase mo del with M ulti-F luid VOF •Multiphase RSM turbulenc e mo del The f ollowing is a list of mo dels tha t are compa tible with the non-it erative solv er, but ma y result in some instabilities and inaccur acies f or c ertain flo w conditions: •RSM turbulenc e mo del •MDM •Non-N ewtonian fluids 2579Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Pressur e-Based S olver Settings•Gener al compr essible flo ws (aer ospac e sup ersonic applic ations) •Reacting sp ecies and an y type of c ombustion including PDF The f ollowing is a list of mo dels tha t are not c ompa tible with the non-it erative solv er: •Mixture mo del •Radia tion mo dels (e xcept S2S) •DPM, spar k, and cr evice mo dels •UDS tr ansp ort •Porous jump •Porous media mo del (anisotr opic r esistanc e) •RSM turbulenc e mo del •Floating op erating pr essur e Imp ortant •The PREST O! pr essur e interpolation scheme , when used with the non-it erative time-ad vance- men t solv er, is less stable than in the c ase of the it erative time-ad vancemen t solv er. As a c on- sequenc e, smaller time st eps ma y be requir ed. •As men tioned ab ove, the default c ontrol settings ar e optimally designed t o obtain a sec ond- order solution. In or der t o sa ve CPU time , in c ases wher e transien t accur acy is not a main c oncern (tha t is, first-or der in tegration in time and spac e), or when NIT A is used t o converge t oward a steady-sta te solution, you ma y want to set the Max. Corrections value t o 1 in the Advanc ed Solution C ontrols dialo g box (Expert tab) f or all tr ansp ort equa tions e xcept pr essur e. 37.3.4. Equa tion Or der For tr ansien t simula tions tha t use the pr essur e-based solv er, the or der in which the mo del equa tions are solv ed c an aff ect the sp eed of c onvergenc e.You c an sp ecify the equa tion or der using the f ollowing text command: solve → set → equation-ordering Note tha t the standard metho d is enabled b y default and c orresponds t o the or dering sho wn in Figur e 28.8: Overview of the I terative Time A dvancemen t Solution M etho d For the S egregate Solver and Figur e 28.9: Overview of the N on-I terative Time A dvancemen t Solution M etho d in the Theor y Guide ; alternatively, you c an selec t the optimized-for-volumetric-expansion metho d, which is recommended f or flo ws in which the densit y is str ongly dep enden t on ther mal eff ects, chemic al comp osition, and so on (such as c ombustion simula tions). This t ext command is not a vailable when a multiphase mo del is enabled . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2580Using the S olver37.4. Densit y-Based S olver S ettings To use the densit y-based solv er y ou must first selec t the solv er type, and det ermine if the simula tion is st eady-sta te or tr ansien t from the Gener alTask P age (see Choosing the S olver (p.2561 )).The densit y based solv er settings ar e available mainly in t wo task pages: the Solution M etho ds Task P age (p.3603 ) and the Solution C ontrols Task P age (p.3606 ). In the Solution M etho ds task page , you c an selec t the f ollowing: •Solution f ormula tion t ype: Implicit or Explicit •Flux Scheme t ype : Roe-FDS, AUSM, or L ow D iffusion R oe-FDS •Flow equa tion and mo del equa tion spa tial discr etiza tion accur acy •For the st eady-sta te solution metho d, you c an selec t additional solution options t o acc elerate conver- genc e –Pseudo tr ansien t solution metho d –Convergenc e acc eleration f or str etched meshes •For the tr ansien t formula tion y ou c an selec t –first-or der implicit –second-or der implicit and f or the e xplicit solv er formula tion, you c an also selec t the e xplicit tr ansien t formula tion In the Solution C ontrols task page , you c an selec t the f ollowing: •For the densit y-based e xplicit solv er, you will sp ecify the C ourant numb er, FAS multigr id le vel, and Residual smo othing •For the densit y-based implicit solv er, you will need t o en ter only the C ourant numb er •For b oth solv er metho ds, you will en ter the under-r elaxa tion fac tors asso ciated with other equa tions solv ed with the flo w equa tions , such as equa tions of the turbulenc e mo del The ab ove options c an b e found in the f ollowing sec tions: 37.4.1. Changing the C ourant Numb er 37.4.2. Convective Flux Types 37.4.3. Convergenc e Acceleration f or Stretched M eshes (C ASM) 37.4.4. Preventing D ivergenc e Using L ocal Under-R elaxa tion 37.4.5. Specifying the Explicit R elaxa tion 37.4.6. Turning On F AS M ultigr id 37.4.1. Changing the C our ant Numb er For ANSY S Fluen t’s densit y-based solv er, the main c ontrol o ver the time-st epping scheme is the Courant numb er (CFL). The time st ep is pr oportional t o the CFL, as defined in Equa tion 28.86 in the Theor y Guide . 2581Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Densit y-Based S olver SettingsLinear stabilit y theor y det ermines a r ange of p ermissible v alues f or the CFL (tha t is, the r ange of v alues for which a giv en numer ical scheme will r emain stable). When y ou sp ecify a p ermissible CFL v alue , ANSY S Fluen t will c omput e an appr opriate time st ep using Equa tion 28.86 in the Theor y Guide . In gener al, tak ing lar ger time st eps leads t o fast er convergenc e, so it is ad vantageous t o set the CFL as large as p ossible (within the p ermissible r ange). The stabilit y limits of the densit y-based implicit and e xplicit f ormula tions ar e signific antly diff erent. The e xplicit f ormula tion has a mor e limit ed r ange and r equir es lo wer CFL settings than do es the densit y-based implicit f ormula tion. Appropriate choic es of CFL f or the t wo formula tions ar e discussed below. 37.4.1.1. Cour ant Numb ers for the D ensit y-Based E xplicit F ormulation Linear stabilit y analy sis sho ws tha t the maximum allo wable CFL f or the multi-stage scheme used in the densit y-based e xplicit f ormula tion will dep end on the numb er of stages used and ho w of ten the dissipa tion and visc ous t erms ar e up dated (see Changing the M ulti-S tage Scheme (p.2602 )). But in gener al, you c an assume tha t the multi-stage scheme is stable f or C ourant numb ers up t o 2.5. This stabilit y limit is of ten lo wer in pr actice because of nonlinear ities in the go verning equa tions . The default CFL f or the densit y-based e xplicit f ormula tion is 1.0, but y ou ma y be able t o incr ease it for some 2D pr oblems .You should gener ally not use a v alue higher than 2.0. If your solution is div erging , tha t is, if residuals ar e rising v ery rapidly , and y our pr oblem is pr operly set up and initializ ed, this is usually a go od sign tha t the C ourant numb er must b e lowered. Depending on the se verity of the star tup c onditions , you ma y need t o decr ease the CFL t o a v alue as lo w as 0.1 to 0.5 t o get star ted. Onc e the star tup tr ansien ts ar e reduc ed y ou c an star t incr easing the C ourant numb er again. 37.4.1.2. Cour ant Numb ers for the D ensit y-Based Implicit F ormulation Linear stabilit y theor y sho ws tha t the densit y-based implicit f ormula tion is unc onditionally stable . However, as with the e xplicit f ormula tion, nonlinear ities in the go verning equa tions will of ten limit stabilit y. The default CFL f or the densit y-based implicit f ormula tion is 5.0. It is of ten p ossible t o incr ease the CFL t o 10, 20, 100, or e ven higher , dep ending on the c omple xity of y our pr oblem. You ma y find tha t a lower CFL is r equir ed dur ing star tup (when changes in the solution ar e highly nonlinear), but it c an be incr eased as the solution pr ogresses . The c oupled AMG solv er has the c apabilit y to det ect div ergenc e of the multigr id cycles within a giv en iteration. If this happ ens, it will aut oma tically r educ e the CFL and p erform the it eration again, and a message will b e pr inted t o the scr een. Five attempts ar e made t o complet e the it eration succ essfully . Upon succ essful c ompletion of the cur rent iteration the CFL is r etur ned t o its or iginal v alue and the iteration pr ocedur e pr oceeds as r equir ed. 37.4.1.3. User Inputs The C ourant numb er is set in the Solution C ontrols Task P age (p.3606 ) (Figur e 37.7: The S olution C ontrols Task P age f or the D ensit y-Based Explicit F ormula tion (p.2583 )). Solution → Controls Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2582Using the S olverFigur e 37.7: The S olution C ontrols Task P age f or the D ensit y-Based E xplicit F ormula tion Enter the v alue f or Cour ant Numb er. When y ou selec t Explicit from the Formula tion drop-do wn list in the Solution M etho ds Task Page (p.3603 ), ANSY S Fluen t will aut oma tically set the Cour ant Numb er to 1; when y ou selec t Implicit from the Formula tion drop-do wn list , the Cour ant Numb er will b e changed t o 5 aut oma tically. 37.4.2. Convective Flux Types The c onvective flux es ar e selec ted fr om the Flux Type drop-do wn list in the Solution M etho ds task page . Solution → Metho ds 2583Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Densit y-Based S olver SettingsYou c an selec t from the f ollowing when using the densit y-based solv er: •Roe flux-diff erence splitting ( Roe-FDS ) Roe-FDS splits the flux es in a manner tha t is c onsist ent with their c orresponding flux metho d eigen- values . It is the default and is r ecommended f or most c ases . •Advection U pstr eam S plitting M etho d (AUSM ) AUSM provides e xact resolution of c ontact and sho ck disc ontinuities and it is less susc eptible t o Carbuncle phenomena. •Low diffusion R oe flux-diff erence splitting ( Low D iffusion Ro e-FDS ) Low D iffusion Ro e-FDS is a vailable when a Sc ale-R esolving S imula tion (SRS) turbulenc e mo del is enabled along with the time-implicit f ormula tion. It reduc es the dissipa tion in turbulenc e calcula tions . This should b e used only f or subsonic flo ws. Note For c ases tha t use an SRS turbulenc e mo del and/or include ac oustic c alcula tions , it is r ecom- mended tha t you use the Roe-FDS with the Bounded C entral D ifferencing (BCD) discr et- ization scheme selec ted f or the flo w equa tions , as this c ombina tion is mor e numer ically robust than Low D iffusion Ro e-FDS and just as accur ate.The BCD scheme alt ers the standar d Roe-FDS scheme such tha t the diffusion is r educ ed. Note tha t if y ou ar e not using an SRS turbulenc e mo del, to acc ess the BCD scheme y ou will first need t o type the solve/set/expert text command and en ter yes when ask ed if y ou w ant to Allow selection of all applicable discretization schemes? . 37.4.3. Convergenc e Acceler ation f or S tretched M eshes (C ASM) When using the densit y-based solv er with the implicit solution f ormula tion in st eady-sta te you c an accelerate the c onvergenc e of y our solution on highly-str etched and anisotr opic meshes (lik e the one used when mo deling e xternal aer odynamic pr oblems) b y selec ting the Convergenc e Acceler ation For S tretched M eshes in the Solution M etho ds task page . For fur ther inf ormation and theor etical back ground on this solution acc eleration option, see Convergenc e Acceleration f or S tretched M eshes in the Theor y Guide .The Convergenc e Acceler ation F or S tretched M eshes option pr ovides an op- timum solution c onvergenc e of the implicit solution metho d. To apply c onvergenc e acc eleration f or str etched meshes , perform the f ollowing: 1.Specify the solv er options b y selec ting Densit y-Based and Stead y in the Gener al task page . 2.Selec t Implicit from the Formula tion drop-do wn list and enable Convergenc e Acceler ation F or Stretched M eshes in the Solution M etho ds task page ( Figur e 37.8: The S olution M etho ds Task P age for the D ensit y-Based Implicit F ormula tion (p.2585 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2584Using the S olverFigur e 37.8: The S olution M etho ds Task P age f or the D ensit y-Based Implicit F ormula tion Extra settings f or C ASM c an b e set using the f ollowing t ext command: solve → set → convergence-acceleration-for-stretched-meshes/ Enter yes in r esponse t o the Use convergence acceleration for stretched meshes (CASM)? question. You will also b e ask ed f or a cut-off on the CFL v alue multiplier . By default this value is set t o 100. Typic ally, you do not need t o adjust this v alue . But if c onvergenc e difficulties ar e encoun tered and r educ tion of the CFL v alue alone do es not help impr ove convergenc e, then it is ad- visable t o reduc e this CFL multiplier cut-off t o a lo wer v alue (f or e xample fr om 100 t o 50, 20 or 10). The use of C ASM c an t ypic ally giv e a much fast er convergenc e over the standar d solution metho d. In gener al, when using C ASM, you do not need t o sp ecify a v ery lar ge CFL v alue as y ou do with the standar d solution metho d. A CFL v alue b etween 5 and 10 is t ypic ally used f or c onverging most flo w 2585Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Densit y-Based S olver Settingsproblems .When the Convergenc e Acceler ation F or S tretched M eshes option is selec ted, the solv er will r un when appr opriate with a v ariable lo cal CFL v alue pr oportional t o the c ell asp ect ratios.Therefore, when the c ell asp ect ratio nears unit y (typic ally far fr om w alls), the lo cal cell CFL v alue will b e the same as the v alue tha t you supplied . However, as the c ell is str etched and the c ell asp ect ratio incr eases (near w alls), the lo cal cell CFL v alue will b e multiplied b y the c ell asp ect ratio v alue .This is tr ue un til the c ell str etching is b eyond the multiplier cut-off v alue sp ecified using the t ext command .The pr o- portional change in CFL v alue on highly str etched c ells helps acc elerate the solution esp ecially on highly pack ed and str etched meshes lik e the one used in mo deling e xternal flo w pr oblems . When the c ell asp ect ratio is selec ted b y default , the densit y based implicit solv er will op erate with an explicit r elaxa tion of 0.5 which c an b e adjust ed fr om the Explicit underrelaxation value entry in solve → set → expert The c onvergenc e of the solution is mainly c ontrolled b y adjusting the CFL v alue .Therefore, if conver- genc e pr oblems ar e enc oun tered, lowering the CFL v alue will help impr ove the c onvergenc e. Additional solution par amet ers t o be adjust ed f or mor e conser vative solution settings ar e: 1.lowering the densit y-based implicit solv er explicit r elaxa tion (solve → set → expert ) 2.adjusting the CFL multiplier cut-off v alue t o a lo wer value (solve → set → convergence-accel- eration-for-stretched-meshes/ ) This solution c onvergenc e metho d is v ery aggr essiv e.Therefore it is of par amoun t imp ortanc e to star t with a go od initial guess esp ecially if y ou star t with sec ond or der spa tial discr etiza tion. To get a go od starting solution with the guess y ou pr ovide , you ar e ad vised t o use the full multi-gr id initializa tion metho d (see Full M ultigr id (FMG) Initializa tion (p.2609 )). Note When selec ting the Convergenc e Acceler ation F or S tretched M eshes option then the Pseudo-T ransien t solution metho d will not b e available .You c an either use Convergenc e Acceler ation F or S tretched M eshes or the Pseudo-T ransien t solution metho d.These t wo options c annot b e used a t the same time . Both metho ds help in obtaining fast er convergenc e on anisotr opic meshes . But one metho d requir es tha t you en ter a CFL v alue , while the other r equir es tha t you en ter a pseudo-time st ep v alue t o mar ch the solution t o convergenc e. It is up t o you t o selec t the metho d with which y ou ar e most c omf ortable . Convergenc e Acceler ation F or S tretched M eshes sho ws an ad vantage o ver the standar d solution metho d, par ticular ly with str etched meshes with lo w Y+ v alues (near unit y).The use of Convergenc e Acceler ation F or S tretched M eshes results in an alt eration of the numer ical dissipa tion of the selec ted flux scheme .This change ma y sligh tly impac t the monit ored loading le vel if c ompar ed with the solution obtained without the use of this option. 37.4.4. Preventing D ivergenc e Using L ocal U nder-Relaxa tion It is a sign of lo cal div ergenc e when the t emp erature and/or pr essur e for individual c ells appr oaches the minimum and/or maximum limits (set in the Solution Limits D ialog Box (p.3610 )), and this c an pr ecede the div ergenc e of the global solution. If either of these quan tities is b eing r eset t o a limiting v alue r e- peatedly (as indic ated b y the appr opriate warning messages in the c onsole), you should check the dimensions , boundar y conditions , and pr operties t o be sur e tha t the pr oblem is set up c orrectly, and try to det ermine the c ause; you c an cr eate a field v ariable c ell r egist er to mar k and displa y cells ha ve Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2586Using the S olvera value equal t o the limit (r efer to Field Variable (p.2763 ) for mor e inf ormation). If the setup app ears appr opriate but the densit y-based solv er still div erges, it is r ecommended tha t you use div ergenc e prevention, which has b een sho wn t o be helpful f or challenging c ases (such as those tha t under go shocks or e xperienc e difficulties r elated t o sp ecies c alcula tions). With this option, Fluen t will iden tify the lo cally div erging c ells and aut oma tically apply a tr eatmen t to them tha t freezes the pr essur e and/or temp erature values (tha t is, sets the under-r elaxa tion fac tor—which is similar t o in Equa tion 28.65 in the Fluent Theor y Guide —to 0) and applies under-r elaxa tion t o the other v ariables .To enable div er- genc e pr evention, use the f ollowing t ext command: solve → set → divergence-prevention → enable? When pr ompt ed, enter yes , and then define the under-r elaxa tion fac tor for the other v ariables: the default v alue of 0.1 is r ecommended , though if this fails t o pr event div ergenc e you c an tr y incr easing this under-r elaxa tion b y reducing the fac tor to 0. Note When y ou decide t o enable div ergenc e pr evention, not e the f ollowing: if the w arning messages indic ate tha t only a small p ercentage of c ells ar e appr oaching the t emp erature and/or pr essur e limits , then y ou c an just c ontinue the c alcula tion; if the p ercentage of c ells is a higher v alue , it is r ecommended tha t you r estar t the c alcula tion fr om initializa tion. 37.4.5. Specifying the E xplicit Relaxa tion To impr ove the c onvergenc e to steady-sta te for some flo w cases when using the densit y-based implicit solv er y ou c an sp ecify the e xplicit r elaxa tion using the f ollowing t ext command: solve → set → expert Enter a v alue b etween 0 and 1 in r esponse t o the Explicit relaxation value prompt. For mor e inf ormation ab out e xplicit r elaxa tion, see Under-R elaxa tion of Variables in the Theor y Guide . 37.4.6. Turning On F AS M ultigr id As discussed in Multigr id M etho d in the Theor y Guide , FAS multigr id is an optional c omp onen t of the densit y-based e xplicit f ormula tion, while AMG multigr id is alw ays on, by default f or the densit y-based implicit f ormula tion. Since near ly all densit y-based e xplicit c alcula tions will b enefit fr om the use of the FAS multigr id convergenc e acc elerator, you should gener ally set a nonz ero numb er of c oarse gr id levels b efore beginning the c alcula tion. For most pr oblems , this will b e the only F AS multigr id par a- met er y ou will need t o set. Should y ou enc oun ter convergenc e difficulties , consider applying one of the metho ds discussed in Setting F AS M ultigr id P aramet ers (p.2596 ). Imp ortant Note tha t you c annot use F AS multigr id with e xplicit time st epping (descr ibed in Temp oral Discretiza tion in the Theor y Guide ) because the c oarse gr id corrections will destr oy the time accur acy of the fine gr id solution. 2587Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Densit y-Based S olver Settings37.4.6.1. Setting C oarse Grid L evels As discussed in Full-A pproxima tion S torage (F AS) M ultigr id in the Theor y Guide , FAS multigr id solv es on succ essiv ely c oarser gr ids and then tr ansf ers c orrections t o the solution back up t o the or iginal fine gr id, ther eby incr easing the pr opaga tion sp eed of the solution and sp eeding c onvergenc e.The most basic w ay you c an c ontrol the multigr id solv er is b y sp ecifying the numb er of c oarse gr id le vels to be used . As explained in Full-A pproxima tion S torage (F AS) M ultigr id in the Theor y Guide , the c oarse gr id le vels are formed b y agglomer ating a gr oup of adjac ent “fine” cells in to a single “coarse ” cell.The optimal numb er of gr id le vels is ther efore pr oblem-dep enden t. For most pr oblems , you c an star t out with 4 or 5 le vels. For lar ge 3D pr oblems , you ma y want to add mor e levels (although memor y restrictions may pr event you fr om using mor e levels, sinc e each c oarse gr id le vel requir es additional memor y). If you b elieve tha t multigr id is c ausing c onvergenc e trouble , you c an decr ease the numb er of le vels. If ANSY S Fluen t reaches a c oarse gr id with one c ell b efore creating as man y levels as y ou r equest ed, it will simply st op ther e.That is, if y ou r equest 5 le vels, and le vel 4 has only 1 c ell, ANSY S Fluen t will create only 4 le vels, sinc e levels 4 and 5 w ould b e the same . To sp ecify the numb er of gr id le vels y ou w ant, set the numb er of Multigr id L evels in the Solution Controls Task P age (p.3606 ) (Figur e 37.7: The S olution C ontrols Task P age f or the D ensit y-Based Explicit Formula tion (p.2583 )). Solution → Controls You c an also set the Max C oarse L evels under FAS M ultigr id C ontrols in the Multigr id tab in the Advanced S olution C ontrols D ialog Box (p.3611 ). Changing the numb er of c oarse gr id le vels in the Solution C ontrols task page will aut oma tically update the numb er sho wn in the Multigr id tab in the Advanced S olution C ontrols D ialog Box (p.3611 ). Coarse gr id le vels ar e created when y ou first b egin it erating . If you w ant to check ho w man y cells are in each le vel, request one it eration and then click Info and selec t Size in the Domain ribbon tab (Mesh group b ox) (as descr ibed in Mesh S ize (p.793)) to list the siz e of each gr id le vel. If you ar e sa t- isfied , you c an c ontinue the c alcula tion; if not , you c an change the numb er of c oarse gr id le vels and check again. For most pr oblems , you will not need t o mo dify an y additional multigr id par amet ers onc e you ha ve settled on an appr opriate numb er of c oarse gr id le vels.You c an simply c ontinue y our c alcula tion until convergenc e. 37.4.6.2. Using R esidual Smo othing t o Incr ease the C our ant Numb er In the densit y-based e xplicit f ormula tion, implicit r esidual smo othing (or a veraging) is a t echnique that can b e used t o reduc e the time st ep r estriction of the solv er, ther eby allo wing the C ourant numb er to be incr eased .The implicit smo othing is implemen ted with an it erative Jac obi metho d, as descr ibed in Implicit R esidual S moothing in the Theor y Guide .Solution C ontrols Task P age (p.3606 ). Solution → Controls By default , the numb er of Iterations for Residual S moothing is set t o zero, indic ating tha t residual smo othing is disabled . If you incr ease the Iterations coun ter to 1 or mor e, you c an en ter the Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2588Using the S olverSmoothing F actor. A smo othing fac tor of 0.5 with 2 passes of the Jac obi smo other is usually adequa te to allo w the C ourant numb er to be doubled . 37.5. Setting A lgebr aic M ultigr id P aramet ers As men tioned ear lier, in most c ases the multigr id solv er will not r equir e an y sp ecial a ttention fr om y ou. If, however, you ha ve convergenc e difficulties or y ou w ant to minimiz e the o verall solution time b y using mor e aggr essiv e settings , you c an monit or the multigr id solv er and mo dify the par amet ers t o impr ove its p erformanc e. (The instr uctions b elow assume tha t you ha ve alr eady begun c alcula tions , sinc e ther e is no need t o monit or the solv er if y ou do not fit in to one of the t wo categor ies ab ove.) To det ermine whether y our c onvergenc e difficulties c an b e alle viated b y mo difying the multigr id settings , you will check if the r equest ed r esidual r educ tion is obtained on each gr id le vel.To minimiz e solution time , you will check t o see if swit ching t o a mor e powerful c ycle will r esult in o verall reduc tion of w ork by the solv er. By default , the fle xible c ycle is used f or all equa tions e xcept pr essur e correction, which uses a V cycle. Typic ally, for a fle xible c ycle only a f ew (5–10) r elaxa tions will b e performed a t the finest le vel and no coarse le vels will b e visit ed. In some c ases one or t wo coarse le vels ma y be visit ed. If the maximum numb er of fine le vel relaxa tions is not sufficien t, you ma y want to incr ease the maximum numb er (as descr ibed in Flexible C ycle P aramet ers (p.2595 )) or swit ch t o a V cycle (as descr ibed in Specifying the Multigr id C ycle Type (p.2591 )). In the pr essur e-based segr egated algor ithm, the pr essur e correction uses a V cycle b y default. If the maximum numb er of c ycles (30 b y default) is not sufficien t, you c an swit ch t o a W c ycle (using the Multigr id tab in the Advanced S olution C ontrols D ialog Box (p.3611 ), as descr ibed in Specifying the Multigr id C ycle Type (p.2591 )). Note tha t efficienc y ma y det eriorate with a W c ycle. You c an tr y incr easing the maximum numb er of c ycles b y incr easing the v alue of Max C ycles in the Multigr id tab , under Fixed C ycle P aramet ers. In the pr essur e-based c oupled algor ithm and the densit y-based implicit f ormula tion, ther e is no pr essur e correction. Inst ead, ther e is a flo w correction, which b y default uses the F c ycle.The densit y-based e x- plicit f ormula tion uses the V cycle as the default flo w correction. Solution → Controls → Advanc ed... 2589Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting A lgebr aic M ultigr id Paramet ersFigur e 37.9: The M ultigr id Tab For additional inf ormation, see the f ollowing sec tions: 37.5.1. Specifying the M ultigr id Cycle Type 37.5.2. Setting the Termina tion and R esidual R educ tion P aramet ers Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2590Using the S olver37.5.3. Setting the S tabiliza tion M etho d 37.5.4. Additional A lgebr aic M ultigr id Paramet ers 37.5.5. Setting F AS M ultigr id Paramet ers 37.5.1. Specifying the M ultigr id C ycle Type By default , the V cycle is used f or the pr essur e equa tion in the pr essur e-based segr egated algor ithm and the fle xible c ycle is used f or all other equa tions with the e xception tha t the F c ycle is used f or ener gy. In the pr essur e-based c oupled algor ithm, the F c ycle is the default f or the c oupled flo w equa tions and f or the ener gy equa tion. All other sc alar equa tions use the fle xible c ycle b y default. In the densit y-based implicit f ormula tion, the F c ycle is default f or the flo w correction. The V cycle is default for the flo w correction in the densit y-based e xplicit f ormula tion. For b oth densit y-based f ormula tions the fle xible c ycle is used f or the sc alar equa tions . (See Multigr id C ycles in the Theor y Guide for a de- scription of these c ycles .) To change the c ycle t ype for an equa tion, you will use the t op p ortion of the Multigr id tab in the Advanced S olution C ontrols D ialog Box (p.3611 ) (Figur e 37.9: The M ultigr id Tab (p.2590 )). For each equa tion, you c an cho ose Flexible ,V-C ycle,W-C ycle, or F-Cycle in the adjac ent drop-do wn list. 37.5.2. Setting the Termina tion and Residual Reduc tion P aramet ers When y ou use the fle xible c ycle f or an equa tion, you c an c ontrol the multigr id p erformanc e by mo di- fying the Termina tion and/or Restr iction criteria for tha t equa tion a t the t op of the Multigr id tab in the Advanced S olution C ontrols D ialog Box (p.3611 ) (Figur e 37.9: The M ultigr id Tab (p.2590 )). Solution → Controls → Advanc ed... The Restr iction criterion is the r esidual r educ tion t oler ance, in Equa tion 28.127 in the Theor y Guide . This par amet er dic tates when a c oarser gr id le vel must b e visit ed (due t o insufficien t impr ovemen t in the solution on the cur rent level).With a lar ger v alue of , coarse le vels will b e visit ed less of ten (and vice versa). The Termina tion criterion, in Equa tion 28.128 in the Theor y Guide , governs when the solv er should r etur n to a finer gr id le vel (tha t is, when the r esiduals ha ve impr oved sufficien tly on the current level). For the V,W, or F c ycle, the Termina tion criterion det ermines whether or not another c ycle should be performed on the finest (or iginal) le vel. If the cur rent residual on the finest le vel do es not sa tisfy Equa tion 28.128 in the Theor y Guide , and the maximum numb er of c ycles has not b een p erformed , ANSY S Fluen t will p erform another multigr id cycle. (The Restr iction par amet er is not used b y the V, W, and F c ycles .) 37.5.3. Setting the S tabiliza tion M etho d The AMG solv er [143] (p.4012 ) builds c oarse le vels b y gr ouping fine le vel cells t o mak e coarse le vel cells, and uses piec ewise c onstan t interpolation. In the Multigr id tab ( Figur e 37.9: The M ultigr id Tab (p.2590 )), you c an cho ose another stabiliza tion metho d rather than the AMG solv er if y ou ar e using a fix ed-t ype cycle (F ,V, or W c ycle); this is a vailable for all equa tions e xcept the flo w correction f or the densit y-based solv er. If desir ed, you c an cho ose the bi-c onjuga te gr adien t stabiliz ed metho d [9] (p.4005 ) (BCGST AB) option, the r ecursiv e pr ojec tion metho d [114] (p.4011 ) (RPM ), or the gener alized minimal r esidual metho d [106] (p.4010 ) (GMRES ) in 2591Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting A lgebr aic M ultigr id Paramet ersorder t o impr ove the c onvergenc e of the linear solv er. BCGSTAB and GMRES c an b e pr econditioned , and all these metho ds c an pr ovide mor e stabilit y and r obustness than the AMG solv er. ANSY S Fluen t usually builds diagonally dominan t ma trices for the linear solv er. However, this is not always possible . A linear sy stem with highly dominan t off-diagonal c oefficien ts ma y occur dur ing dis- cretiza tion of c omple x ph ysical mo dels such as multiphase c avitation. Using a stabiliza tion metho d in such c ases c an b e helpful. In addition, the AMG c onvergenc e in par allel c an b e impr oved using the BCGST AB or GMRES option with AMG. It is r ecommended tha t you a ttempt a solution first with BCGST AB; the GMRES is usually mor e robust and mor e lik ely t o converge, but it is mor e demanding in terms of memor y usage and solv er time . If you ar e using the pr essur e-based segr egated solv er and the flo w is inc ompr essible , an additional stabiliza tion metho d for the algebr aic multigr id solv er will app ear in the Stabiliza tion M etho d drop- down list. This is the c onjuga te gr adien t metho d, or CG[9] (p.4005 ) and will b e available only f or the pressur e equa tion. This metho d is t ypic ally used in c onjunc tion with an AMG pr econditioner (an y available AMG metho d).The C G formula tion r equir es a symmetr ic sy stem ma trix. Such ma trices result from the finit e volume discr etiza tion of st eady or tr ansien t elliptic op erators, such as the pr essur e correction equa tion in the inc ompr essible c ase.The C G metho d pr ovides a useful alt ernative to BC GSTAB, RPM, and GMRES, sinc e it r educ es the memor y requir emen ts and the numb er of floa ting p oint op era- tions , esp ecially when c ompar ed t o BC GSTAB. In addition, in tr ansien t pressur e-based segr egated solv ers, as t ypic ally used in LES and/or NIT A simula tions , the solution of the pr essur e correction equa tion c onstitut es a signific ant shar e of the o verall c omputa tional eff ort. Note tha t when div ergenc e is det ected f or the AMG solv er, the BC GSTAB metho d and/or the C G metho d, then an alt ernate metho d will b e used f or an it eration as a fallback, and y ou will b e inf ormed in the c onsole tha t an equa tion is b eing stabiliz ed t o enhanc e linear solv er robustness . If you see such console messages r epeatedly f or flo w-related equa tions , it is an indic ation tha t you need t o revise the settings in the Solution M etho ds task page and/or the Algebr aic M ultigr id C ontrols group b ox of the Advanc ed S olution C ontrols dialo g box. 37.5.4. Additional A lgebr aic M ultigr id P aramet ers There ar e se veral additional par amet ers tha t control the algebr aic multigr id solv er, but ther e will usually be no need t o mo dify them. These additional sc alar and c oupled par amet ers ar e all c ontained in the Multigr id tab in the Advanced S olution C ontrols D ialog Box (p.3611 ) (Figur e 37.9: The M ultigr id Tab (p.2590 )). Solution → Controls → Advanc ed... Imp ortant When using the densit y-based e xplicit f ormula tion or the pr essur e-based solv er with an y of the segr egated algor ithms , descr ibed in Pressur e-Velocity Coupling in the Theor y Guide and Choosing the P ressur e-Velocity Coupling M etho d (p.2570 ), only Scalar P aramet ers are set in the Multigr id tab . If you use the densit y-based implicit or the pr essur e-based c oupled algor ithm, descr ibed in Coupled A lgor ithm in the Theor y Guide , then y ou c an set the Coupled P aramet ers. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2592Using the S olver37.5.4.1. Fixed C ycle P aramet ers For the fix ed ( V,W, and F) multigr id cycles, you c an c ontrol the numb er of pr e- and p ost-r elaxa tions ( and in Multigr id C ycles in the Theor y Guide ).Pre-Sweeps sets the numb er of r elaxa tions t o perform b efore mo ving t o a c oarser le vel.Post-S weeps sets the numb er to be performed af ter coarser le vel corrections ha ve been applied . Normally , under Scalar P aramet ers, one p ost-r elaxa tion is performed and no pr e-relaxa tions ar e done (tha t is, and ), but in r are cases , you ma y need t o incr ease the v alue of to 1 or 2. Under Coupled P aramet ers, three p ost-r elaxa tions ar e performed b y default with no pr e-relaxa tions . If you ar e using the pr essur e-based c oupled solv er for a steady simula tion with pseudo-tr ansien t enabled , three p ost-r elaxa tions ar e performed under Scalar P aramet ers also . Imp ortant •If you ar e using AMG with V-cycle t o solv e an ener gy equa tion with a solid c onduc tion mo del presen ted with anisotr opic or v ery high c onduc tivit y coefficien t, ther e is a p ossibilit y of div er- genc e with a default p ost-r elaxa tion sw eep of . In such c ases y ou should incr ease the p ost- relaxa tion sw eep (t o sa y ) in the AMG sec tion f or b etter convergenc e when using the pr essur e- based segr egated algor ithms . •It is r ecommended tha t you use the F ixed F-c ycle f or the ener gy equa tion when r unning par allel ANSY S Fluen t. 37.5.4.2. Coarsening P aramet ers For all multigr id cycle t ypes, you c an c ontrol the maximum numb er of c oarse le vels ( Max C oarse Levels under Scalar or Coupled P aramet ers) tha t will b e built b y the multigr id solv er. Sets of c oarser simultaneous equa tions ar e built un til the maximum numb er of le vels has b een cr eated, or the c oarsest le vel has only 3 equa tions . Each le vel has ab out half as man y unk nowns as the pr evious level, so c oarsening un til ther e ar e only a f ew c ells lef t will r equir e ab out as much t otal c oarse-le vel coefficien t storage as w as requir ed on the fine mesh. Reducing the maximum c oarse le vels will r educ e the memor y requir emen ts, but ma y requir e mor e iterations t o achie ve a c onverged solution. Setting Max C oarse L evels to 0 tur ns off the algebr aic multigr id solv er. Another c oarsening par amet er y ou c an c ontrol is the incr ease in c oarseness on succ essiv e levels.The Coarsen b y par amet er sp ecifies the numb er of fine gr id cells tha t will b e gr oup ed t ogether t o cr eate a coarse gr id cell.The algor ithm gr oups each c ell with its str ongest neighb or, then gr oups the c ell and its str ongest neighb or with the neighb or’s str ongest neighb or, continuing un til the desir ed coarsening is achie ved.Typic al values f or the sc alar par amet ers ar e in the r ange fr om 2 t o 10, with the default v alue of 2 f or the G auss-S eidel smo other giving the b est p erformanc e, but also the gr eatest memor y use . For c oupled par amet ers and sc alar par amet ers when using the pr essur e-based c oupled solv er with pseudo-tr ansien t enabled , the default v alues of 4 (f or 2D) and 8 (f or 3D) f or the IL U 2593Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting A lgebr aic M ultigr id Paramet erssmo other giv e the b est p erformanc e.You should not adjust this par amet er unless y ou need t o reduc e the memor y requir ed t o run a pr oblem. Imp ortant Depending on the smo other t ype, Gauss-S eidel or IL U, the Coarsen b y and Post-S weeps settings should b e changed as f ollows when selec ting the non-default smo other t ype: ILU :Post-S weeps =3 and Coarsen b y = 8 Gauss-S eidel :Post-S weeps =1 and Coarsen b y = 2 For the sc alar and c oupled equa tions , you ha ve the f ollowing AMG c oarsening options . Note tha t these c an b e used singly or in c ombina tion with each other . •Conser vative Coarsening This option is enabled b y default , and impr oves c onvergenc e for difficult pr oblems b y tuning multigr id coarsening based on c oefficien t str engths and , in par allel c omputa tions , the par titioning . •Aggr essiv e Coarsening This option sp ecifies the use of a v ersion of the AMG solv er tha t is optimiz ed f or higher , mor e ag- gressiv e coarsening r ates. It is r ecommended if the AMG solv er div erges with the default settings , and is mor e lik ely t o be beneficial in the f ollowing c ases: –if the c orresponding Coarsen b y field is set t o a v alue gr eater than 2 (which is the c ase b y default if you ar e using the densit y-based implicit or the pr essur e-based c oupled scheme) –if you ar e using higher c ore coun ts •Laplac e Coarsening This option is disabled b y default , so tha t a c ell’s str ongest neighb or is iden tified based on the magnitude of its in teraction with the c ell in question. Enabling it sp ecifies tha t Laplac e coefficien ts are used t o evalua te neighb or str ength when gr ouping c ells f or c oarsening .This ma y impr ove stabilit y in some c ases b ecause the c oarser le vels will not change as the solution e volves. It ma y also r educ e computa tion time , par ticular ly at high c ore coun ts, because the c oarse le vels don ’t need t o be recreated e very iteration. 37.5.4.3. Smo other Types Two smo other t ypes ar e available f or sc alar and c oupled par amet ers.Gauss-S eidel is the simplest smo other t ype and is r ecommended when using the pr essur e-based segr egated algor ithm. ILU is mor e CPU in tensiv e, but has b etter smo othing pr operties f or blo ck-c oupled sy stems such as the pressur e-based c oupled solv er and the densit y-based implicit f ormula tion. The default sc alar Smoother Type is Gauss-S eidel , while the c oupled Smoother Type is ILU.The ILU smo other is also used f or sc alar equa tions when using the c oupled solv er with pseudo-tr ansien t enabled . For mor e information ab out the t wo smo other t ypes, see The C oupled and Sc alar AMG S olvers in the Theor y Guide . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2594Using the S olver37.5.4.4. Flexible C ycle P aramet ers To change the maximum numb er of r elaxa tions , incr ease or decr ease the v alue of Max F ine Relaxa- tions or Max C oarse Relaxa tions in the Multigr id tab in the Advanced S olution C ontrols D ialog Box (p.3611 ) (Figur e 37.9: The M ultigr id Tab (p.2590 )) under Flexible C ycle P aramet ers. Solution → Controls → Advanc ed... 37.5.4.5. Setting the Verb osit y The st eps f or monit oring the solv er ar e as f ollows: 1.Set multigr id Verb osit y to 1 or 2 in the Multigr id tab in the Advanced S olution C ontrols D ialog Box (p.3611 ). Solution → Controls → Advanc ed... 2.Request a single it eration using the Run C alcula tion Task P age (p.3640 ). Solution → Run C alcula tion If you set the v erbosity to 2, the inf ormation pr inted in the ANSY S Fluen t console f or each equa tion will include the f ollowing: •equa tion name •equa tion t oler ance (comput ed b y the solv er using a nor maliza tion of the sour ce vector) •residual v alue af ter each fix ed multigr id cycle or fine r elaxa tion f or the fle xible c ycle •numb er of equa tions in each multigr id le vel, with the z eroth le vel being the or iginal (finest-le vel) sy stem of equa tions Note tha t the r esidual pr inted a t cycle or r elaxa tion 0 is the initial r esidual b efore an y multigr id cycles are performed . When v erbosity is set t o 1, only the equa tion name , toler ance, and r esiduals ar e pr inted. A portion of a sample pr intout is sho wn b elow: pressure correction equation: tol. 1.2668e-05 0 2.5336e+00 1 4.9778e-01 2 2.5863e-01 3 1.9387e-01 multigrid levels: 0 918 1 426 2 205 3 97 4 45 5 21 6 10 7 4 2595Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting A lgebr aic M ultigr id Paramet ers37.5.4.6. Returning t o the D efault Multigrid P aramet ers If you change the multigr id par amet ers, but y ou then w ant to retur n to ANSY S Fluen t’s default settings , you c an click the Default butt on in the Multigr id tab . ANSY S Fluen t will change all settings t o the defaults , and the Default butt on will b ecome the Reset butt on.To get y our settings back again, you can click the Reset butt on. 37.5.5. Setting F AS M ultigr id P aramet ers For most c alcula tions , you will not need t o mo dify an y FAS multigr id par amet ers onc e you ha ve set the numb er of c oarse gr id le vels. If, however, you enc oun ter convergenc e difficulties , you ma y consider the f ollowing suggest ed pr ocedur es. Imp ortant Recall tha t FAS multigr id is used only b y the densit y-based e xplicit f ormula tion. 37.5.5.1. Combating C onvergenc e Trouble Some pr oblems ma y appr oach c onvergenc e steadily a t first , but then the r esiduals will le vel off and the solution will “get stuck. ” In some c ases (f or e xample , long thin duc ts), this c onvergenc e trouble may be due t o multigr id’s slo w pr opaga tion of pr essur e inf ormation thr ough the domain. In such cases , you should tur n off multigr id b y setting Multigr id L evels to 0 in the Solution C ontrols Task Page (p.3606 ). 37.5.5.2. “Industrial-Str ength ” FAS Multigrid In some c ases , you ma y find tha t your pr oblem is c onverging , but a t an e xtremely slo w rate. Such problems c an of ten b enefit fr om a mor e aggr essiv e form of multigr id, which will sp eed up the propaga tion of the solution c orrections . For such pr oblems , you c an tr y the “industr ial-str ength ” multigr id settings . Imp ortant These settings ar e very aggr essiv e and assume tha t the solution inf ormation passed thr ough the multigr id le vels is somewha t accur ate. For this r eason, you should only a ttempt the procedur e descr ibed her e af ter y ou ha ve performed enough it erations tha t the solution is off t o a go od star t. Using “industr ial-str ength ” multigr id too ear ly in the c alcula tion pr o- cess—when the solution is far fr om c orrect—will not help c onvergenc e and ma y cause the c alcula tion t o become unstable , as v ery inc orrect values ar e pr opaga ted quick ly to the original gr id. Note also tha t while these multigr id settings will usually r educ e the t otal numb er of it erations r equir ed t o reach c onvergenc e, the y will gr eatly incr ease the c ompu- tation time f or each multigr id cycle.Thus the solv er will b e performing f ewer but longer iterations . The str ategy emplo yed is as f ollows: •Increase the numb er of it erations p erformed on each gr id le vel before pr oceeding t o a c oarser le vel •Increase the numb er of it erations p erformed on each gr id le vel af ter retur ning fr om a c oarser le vel Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2596Using the S olver•Allow full c orrection tr ansf er fr om one le vel to the ne xt finer le vel, inst ead of tr ansf erring r educ ed v alues of the c orrections •Do not smo oth the in terpolated c orrections when the y are transf erred fr om a c oarser gr id to a finer gr id You c an set all of the par amet ers f or this str ategy under FAS M ultigr id C ontrols in the Multigr id tab in the Advanced S olution C ontrols D ialog Box (p.3611 ) (Figur e 37.10: The A dvanced S olution C ontrols Dialog Box (p.2598 )) and then c ontinue the c alcula tion. Solution → Controls → Advanc ed... 2597Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting A lgebr aic M ultigr id Paramet ersFigur e 37.10: The A dvanc ed S olution C ontrols D ialo g Box Increasing the numb er of it erations p erformed on each gr id le vel b efore pr oceeding t o a c oarser le vel (the v alue of descr ibed in Multigr id C ycles in the Theor y Guide ) will impr ove the solution passed from each finer gr id le vel to the ne xt coarser gr id le vel.Try incr easing the v alue of Pre-Sweeps (under FAS M ultigr id C ontrols,not under Algebr aic M ultigr id C ontrols) to 10. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2598Using the S olverIncreasing the numb er of it erations p erformed on each le vel af ter retur ning fr om a c oarser le vel will impr ove the c orrections passed fr om each c oarser gr id le vel to the ne xt finer gr id le vel. Errors in tro- duced on the c oarser gr id le vels c an ther efore be reduc ed b efore the y are passed fur ther up the gr id hier archy to the or iginal gr id.Try incr easing the v alue of Post-S weeps (under FAS M ultigr id C ontrols, not under Algebr aic M ultigr id C ontrols) to 10. By default , the full v alues of the multigr id corrections ar e not tr ansf erred fr om a c oarser gr id to a finer gr id; only 60% of the v alue is tr ansf erred.This pr events lar ge er rors fr om tr ansf erring quick ly up to the or iginal gr id and c ausing the c alcula tion t o become unstable . It also pr events a “good” solution from pr opaga ting quick ly to the or iginal gr id. However, by incr easing the Correction Reduc tion to 1, you c an tr ansf er the full v alues fr om c oarser t o finer gr id le vels, speeding the pr opaga tion of the solution and , usually , the c onvergenc e as w ell.The Species C orrection Reduc tion sets the fac tor b y which t o reduc e the magnitude of the sp ecies c orrections t o stabiliz e the multigr id calcula tion. This item app ears only when sp ecies tr ansp ort is b eing mo deled . When the c orrections on a c oarse gr id ar e passed back t o the ne xt finer gr id le vel, the v alues ar e, by default , interpolated and then smo othed . Disabling the smo othing so tha t the ac tual v alue in a c oarse grid cell is assigned t o the fine gr id cells tha t mak e it up c an also aid c onvergenc e.To disable smo othing , set the Correction S moothing to 0. Large disc ontinuities b etween c ells will b e smo othed out implicitly as a r esult of the additional Post-S weeps performed . The Cour ant Numb er Reduc tion sets the fac tor b y which t o reduc e the C ourant numb er for c oarse grid le vels (tha t is, every level except the finest). Some r educ tion of time st ep (such as the default 0.9) is t ypic ally r equir ed b ecause the stabilit y limit c annot b e det ermined as pr ecisely on the ir regular ly shap ed c oarser gr id cells. 37.6. Setting S olution Limits In or der t o keep the solution stable under e xtreme c onditions , ANSY S Fluen t provides limits tha t keep the solution within an acc eptable r ange .You c an c ontrol these limits with the Solution Limits D ialog Box (p.3610 ) (Figur e 37.11: The S olution Limits D ialog Box (p.2599 )). Solution → Controls Limits ... Figur e 37.11: The S olution Limits D ialo g Box 2599Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting S olution LimitsFluen t applies limiting v alues f or pr essur e, static t emp erature, and turbulenc e quan tities . Fluen t also applies a minimum v olume fr action f or the ma trix solution in E uler ian multiphase simula tions r un on a double-pr ecision solv er.The pur pose of these limits is t o keep the absolut e pr essur e or sta tic t emp er- ature from b ecoming z ero, nega tive, or e xcessiv ely lar ge dur ing the c alcula tion, and t o keep the turbu- lenc e quan tities fr om b ecoming e xcessiv e.The pur pose of the minimum v olume fr action is t o avoid singular ity of the solution ma trix when the v olume fr action t ends t o zero. Typic ally, you will not need t o change the default solution limits . If pressur e, temp erature, or turbulenc e quan tities ar e being r eset t o the limiting v alue r epeatedly (as indic ated b y the appr opriate warning messages in the c onsole), you should check the dimensions , boundar y conditions , and pr operties t o be sure tha t the pr oblem is set up c orrectly and tr y to det ermine wh y the v ariable in question is getting so close t o zero or so lar ge.You c an cr eate a field v ariable c ell r egist er to mar k and displa y cells ha ve a value equal t o the limit (r efer to Field Variable (p.2763 ) for mor e inf ormation). In v ery rare cases , you may need t o change the solution limits , but only do so if y ou ar e sur e tha t you understand the r eason for the solv er’s unusual b ehavior. For e xample , you ma y know tha t the t emp erature in y our domain will e xceed 5000 K. Be sur e tha t an y temp erature-dep enden t properties ar e appr opriately defined f or high t emp eratures if y ou incr ease the maximum t emp erature limit. Another r are example is when the actual v olume fr action in the domain needs t o go b elow a saf e limit of 1e-08, such as in nuclea tion and disp ersion of v ery low amoun ts of c ontaminan ts in a sy stem. By reducing this limit y ou ma y enc oun ter instabilit y pr oblems . Imp ortant The absolut e pr essur e limit is enf orced only f or fluid ma terials tha t are mo deled using the ideal-gas or one of the r eal-gas-* densit y metho ds. For ma terials tha t use the c ompr essible-liquid or a user-defined c ompr essible fluid (liquid or gas) densit y metho d, a pr essur e limit is used t o ensur e tha t the densit y remains p ositiv e, but the ac tual pr essur e value itself is not limit ed. Note tha t if y ou ar e using the densit y-based solv er and the t emp erature and/or pr essur e values ar e appr oaching the minimum and/or maximum limits , you c an enable div ergenc e pr evention t o apply under-r elaxa tion t o the v ariables in selec t cells r ather than changing the limits . For details , see Preventing Divergenc e Using L ocal U nder-R elaxa tion (p.2586 ). For additional inf ormation, see the f ollowing sec tions: 37.6.1. Limiting the Values of S olution Variables 37.6.2. Adjusting the P ositivit y Rate Limit 37.6.3. Resetting S olution Limits 37.6.1. Limiting the Values of S olution Variables The limiting minimum and maximum v alues f or absolut e pr essur e ar e sho wn in the Minimum and Maximum A bsolut e Pressur e fields . If the ANSY S Fluen t calcula tion pr edic ts a v alue less than the Minimum A bsolut e Pressur e or gr eater than the Maximum A bsolut e Pressur e, the c orresponding limiting v alue will b e used inst ead. Similar ly, the Minimum and Maximum Temp erature are limiting values f or ener gy calcula tions . The Minimum Turb . Kinetic E nergy,Minimum Turb . Dissipa tion R ate, and the Maximum Turb . Visc osit y Ratio are limiting v alues f or turbulen t calcula tions . If the c alcula tion pr edic ts a v alue f or or tha t is less than the appr opriate limiting v alue (tha t is,Minimum Turb . Kinetic E nergy or Minimum Turb . Dissipa tion R ate, respectively), then the limiting v alue will b e used inst ead. For the visc osity Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2600Using the S olverratio limit , ANSY S Fluen t uses the limiting maximum v alue of turbulen t visc osity ( ) in the flo w field r elative to the laminar visc osity. If the r atio c alcula ted b y ANSY S Fluen t exceeds the limiting v alue , the r atio is set t o the limiting v alue b y limiting to the nec essar y value . For E uler ian and M ixture multiphase simula tions r un on a double-pr ecision solv er using the implicit volume fr action f ormula tion, if the pr edic tion of v olume fr action falls b elow the v alue sp ecified f or Minimum Vol. Frac. for M atrix S olution , ANSY S Fluen t will use the limiting v alue in the ma trix solution for phase-sp ecific equa tions , dep ending on the mo del. For the multiphase mo dels supp orting the e xplicit v olume fr action f ormula tion and f or the VOF mo del, the Volume F raction C utoff limit sp ecified in the Multiphase M odel dialo g box will ser ve as a limiting value when solving phase-sp ecific equa tions , dep ending on the mo del. Note The E uler ian multiphase mo del uses the sp ecified solution limits f or solving M omen tum, Turbulenc e, Ener gy, Species , and UDS equa tions , wher eas the VOF and M ixture multiphase models use the sp ecified limits f or solving S pecies and UDS equa tions . 37.6.2. Adjusting the P ositivit y Rate Limit In ANSY S Fluen t’s densit y-based solv er, the r ate of r educ tion of t emp erature is c ontrolled b y the Pos- itivit y Rate Limit .The default v alue of 0.2, for e xample , means tha t temp erature is not allo wed t o decr ease b y mor e than 20% of its pr evious v alue fr om one it eration t o the ne xt. If the t emp erature change e xceeds this limit , the time st ep in tha t cell is r educ ed t o br ing the change back in to range and a “time st ep r educ ed” warning is pr inted. (This r educ ed time st ep will b e used f or the solution of all v ariables in the c ell, not just f or temp erature.) Rapid r educ tion of t emp erature is an indic ation tha t the t emp erature ma y become nega tive. Repeated “time st ep r educ ed” warnings should aler t you tha t something is wr ong in y our pr oblem setup . (If the w arning messages st op app earing, the c alcula tion may ha ve “recovered” from the time-st ep r educ tion.) Imp ortant For high-sp eed flo w, if y our solution is div erging par ticular ly for the ener gy equa tion, then lowering this limit t o 0.05 or 0.02 migh t help in o vercoming div ergenc e. 37.6.3. Resetting S olution Limits If you change and sa ve the v alue of one of the solution limits , but y ou then w ant to retur n to the default limits set b y ANSY S Fluen t, you c an r eop en the Solution Limits D ialog Box (p.3610 ) and click the Default butt on. ANSY S Fluen t will change the v alues t o the defaults and the Default butt on will b ecome the Reset butt on.To get y our v alues back again, you c an click the Reset butt on. 37.7. Setting M ulti-S tage Time-S tepping P aramet ers The most c ommon par amet er y ou will change t o control the c onvergenc e of the multi-stage time- stepping scheme is the C ourant numb er. Instr uctions f or mo difying the C ourant numb er ar e pr esen ted in Changing the C ourant Numb er (p.2581 ).The Multi-S tage tab is acc essible fr om the Advanc ed S olution Controls dialo g box when using the densit y-based e xplicit f ormula tion. 2601Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting M ulti-S tage Time-S tepping P aramet ersFor additional inf ormation, see the f ollowing sec tion: 37.7.1. Changing the M ulti-S tage Scheme 37.7.1. Changing the M ulti-S tage Scheme It is p ossible t o mak e se veral changes t o the multi-stage time-st epping scheme itself .You c an change the numb er of stages and set a new multi-stage c oefficien t for each stage .You c an also c ontrol whether or not dissipa tion and visc ous str esses ar e up dated a t each stage .These changes ar e made in the Multi-S tage tab in the Advanced S olution C ontrols D ialog Box (p.3611 ) (Figur e 37.12: The M ulti- Stage Tab (p.2602 )). Solution → Controls Advanc ed... Figur e 37.12: The M ulti-S tage Tab Imp ortant You should not a ttempt t o mak e changes t o ANSY S Fluen t’s multi-stage scheme unless y ou are very familiar with multi-stage schemes and ar e in terested in tr ying a diff erent scheme found in the lit erature. 37.7.1.1. Changing the C oefficients and Numb er of Stages By default , the ANSY S Fluen t multi-stage scheme uses 3 stages f or st eady-sta te solutions with c oeffi- cien ts of 0.2075, 0.5915, and 1.0, and 4 stages f or unst eady solutions with c oefficien ts of 0.25, 0.3333, 0.5, and 1.0. You c an decr ease or incr ease the numb er of stages using the ar row butt ons f or Numb er of S tages in the Multi-S tage tab . (If you w ant to incr ease the numb er of stages b eyond fiv e, you will need t o use the t ext-interface command solve/set/multi-stage .) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2602Using the S olverFor each stage , you c an mo dify the Coefficien t. Coefficien ts must b e gr eater than 0 and less than 1. The final stage should alw ays ha ve a c oefficien t of 1. 37.7.1.2. Contr olling Up dat es t o D issipation and Visc ous Str esses For each stage , you c an indic ate whether or not ar tificial dissipa tion and visc ous str esses ar e evalua ted. If a Dissipa tion box is selec ted f or a par ticular stage , artificial dissipa tion will b e up dated on tha t stage . If not selec ted, artificial dissipa tion will r emain “frozen” at the v alue of the pr evious stage . If a Visc ous box is selec ted f or a par ticular stage , visc ous str esses will b e up dated on tha t stage . If not selec ted, visc ous str esses will r emain “frozen” at the v alue of the pr evious stage .Viscous str esses should alw ays be comput ed on the first stage , and succ essiv e evalua tions will incr ease the “robustness ” of the solution pr ocess, but will also incr ease the e xpense (tha t is, incr ease the CPU time p er it eration). For st eady pr oblems , the final solution is indep enden t of the stages on which visc ous str esses ar e updated. 37.7.1.3. Resetting the Multi-Stage P aramet ers If you change the multi-stage par amet ers, but y ou then w ant to retur n to the default scheme set b y ANSY S Fluen t, you c an click the Default butt on in the Multi-S tage tab in the Advanced S olution Controls D ialog Box (p.3611 ). ANSY S Fluen t will change the v alues t o the defaults and the Default butt on will b ecome the Reset butt on.To get y our v alues back again, you c an click the Reset butt on. 37.8. Selec ting G radien t Limit ers The default gr adien t limit er in ANSY S Fluen t is the Standar d limit er. Each of the limit ers is descr ibed in detail in Gradien t Limit ers in the Theor y Guide .The gr adien t limit ers ar e acc essible fr om the Expert tab in the Advanc ed S olution C ontrols dialo g box. Solution → Controls Advanc ed... You c an selec t Standar d,Multidimensional , or Differentiable from the Spatial D iscr etiza tion Limit er Type drop-do wn list. Each of these options c an also b e acc essed b y typing the f ollowing t ext command: solve → set → slope-limiter-set Choose fr om the f ollowing options: Type Criterion Default ( TVD) slop e limit er 0 Multidimensional ( TVD) slop e limit er 1 Differentiable slop e limit er 2 Note tha t the Default(TVD) slope limiter in the TUI is equiv alen t to the Standar d option in the GUI. For each of the gr adien t limit er metho ds, ANSY S Fluen t provides t wo limiting dir ections: 2603Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Selec ting G radien t Limit ers•Cell t o Face Limiting is wher e the limit ed v alue of the r econstr uction gr adien t is det ermined a t cell fac e centers.This is the default metho d. •Cell t o Cell Limiting is wher e the limit ed v alue of the r econstr uction gr adien t is det ermined along a sc aled line b etween t wo adjac ent cell c entroids . On an or thogonal mesh (or when c ell-t o-cell dir ection is par allel to fac e area dir ection) this metho d becomes equiv alen t to the default c ell to fac e metho d. For smo oth field variation, cell to cell limiting ma y pr ovide less numer ical dissipa tion on meshes with sk ewed c ells. ANSY S Fluen t also pr ovides the option t o apply a limit er filt er to the Standar d and Differentiable limit ers.The pur pose of the limit er filt er is t o main tain higher-or der accur acy for the main flo w variables . It suppr esses limit er in tervention ar ising fr om small numer ical noise , while main taining limit er control when ther e ar e ac tual disc ontinuities or lar ge gr adien ts in the solution (a t sho cks, boundar y layers, and so on). The limit er filt er can also help in impr oving the appar ent convergenc e of the solution r esidual. To use the limit er filt er enable Apply Limit er F ilter.When the limit er filt er is tur ned on, then b y default the filt er mechanism is applied t o the main flo w and turbulen t variables only .The filt er mechanism is based on c ompar ing lo cal cell changes t o average global domain changes of a par ticular flo w variable . When the lo cal changes ar e very small c ompar ed t o the a verage global changes , then the limit er in ter- vention will b e suppr essed . Note The limit er filt er is not a vailable when using the Multidimensional limit er. 37.9. Initializing the S olution Before star ting y our CFD simula tion, you must pr ovide ANSY S Fluen t with an initial “guess ” for the solution flo w field . In man y cases , you must tak e extra care to pr ovide an initial solution tha t will allo w the desir ed final solution t o be attained . A real-lif e sup ersonic wind tunnel, for e xample , will not “start” if the back pr essur e is simply lo wered t o its op erating v alue; the flo w will chok e at the tunnel thr oat and will not tr ansition t o sup ersonic .The same holds tr ue f or a numer ical simula tion: the flo w must b e initializ ed t o a sup ersonic flo w or it will simply chok e and r emain subsonic . There ar e two metho ds for initializing the solution: •Initializ e the en tire flo w field (in all c ells). Three metho ds ar e available: –Standar d initializa tion (see Initializing the En tire Flow Field U sing S tandar d Initializa tion (p.2605 )) –FMG initializa tion (see Full M ultigr id (FMG) Initializa tion (p.2609 )) –Hybrid initializa tion (see Hybrid Initializa tion (p.2611 )) •Patch v alues or func tions f or selec ted flo w variables in selec ted c ell z ones or c ell regist ers. Imp ortant •Before pa tching initial v alues in selec ted c ells, you must first initializ e the en tire flo w field .You can then pa tch the new v alues o ver the initializ ed v alues f or selec ted v ariables . •If you ar e using one of the f ollowing in y our analy ses: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2604Using the S olver–user-defined r eal gas mo del (UDR GM) –user-defined densit y (via UDF) –solution-dep enden t expressions then b efore initializing the solution using either the Hybr id Initializa tion metho d or v alues from a sp ecific z one selec ted in the Comput e fr om drop-do wn list , you must first p erform standar d initializa tion with no z one selec ted fr om the Comput e fr om drop-do wn list. In the first st ep, the standar d initializa tion will yield the pr eliminar y solution v alues , which will b e then used in the sec ond st ep t o obtain the desir ed initial v alues .The r ecommended workflow will help r esolv e potential cir cular dep endencies (such as the dep endenc e of solution initializa tion v alues on ma terial pr operties or e xpressions and dep endenc e of material pr operties or e xpressions on solution v alues). For additional inf ormation, see the f ollowing sec tions: 37.9.1. Initializing the En tire Flow Field U sing S tandar d Initializa tion 37.9.2. Patching Values in S elec ted C ells 37.9.1. Initializing the E ntire Flow Field U sing S tandar d Initializa tion Before you star t your c alcula tions or patch initial v alues f or selec ted v ariables in selec ted c ells ( Patching Values in S elec ted C ells (p.2607 )) you must initializ e the flo w field in the en tire domain. The Solution Initializa tion Task P age (p.3620 ) (Figur e 37.13: The S olution Initializa tion Task P age (p.2606 )) allo ws you to set initial v alues f or the flo w variables and initializ e the solution using these v alues . Solution → Initializa tion 2605Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Initializing the S olutionFigur e 37.13: The S olution Initializa tion Task P age You c an c omput e the v alues fr om inf ormation in a sp ecified z one , enter them manually , or ha ve the solv er comput e average v alues based on all z ones .You c an also indic ate whether the sp ecified v alues for v elocities ar e absolut e or r elative to the v elocity in each c ell z one .The st eps f or standar d initializa tion are as f ollows: 1.Selec t Standar d Initializa tion as the Initializa tion M etho d. 2.Set the initial v alues: •To initializ e the flo w field using the v alues set f or a par ticular z one , selec t the z one name in the Comput e from drop-do wn list. All values under the Initial Values heading will aut oma tically b e comput ed and updated based on the c onditions defined a t the selec ted z one . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2606Using the S olver•To initializ e the flo w field using c omput ed a verage v alues , selec t all-z ones in the Comput e from drop- down list. ANSY S Fluen t will c omput e and up date the Initial Values based on the c onditions defined at all b oundar y zones . •If you w ant to change one or mor e of the v alues , you c an en ter new v alues manually in the fields ne xt to the appr opriate variables . If you pr efer to en ter all v alues manually , you c an do so without selec ting a zone in the Comput e from list. For sp ecies tr ansp ort cases with a single phase flo w, you c an selec t boundar y sp ecies t o be displa yed in the list using the Selec t Boundar y Species dialo g box (see Fig- ure 15.3: The S elec t Boundar y Species D ialog Box (p.1623 )) tha t can b e acc essed b y click ing Species in the Solution Initializa tion task page . 3.If your pr oblem in volves mo ving r eference frames or sliding meshes , indic ate whether the initial v elocities are absolut e velocities or v elocities r elative to the motion of each c ell z one b y selec ting Absolut e or Rel- ative to Cell Z one under Referenc e Frame . (If no z one motion o ccurs in the pr oblem, the t wo options are equiv alen t.) The default r eference frame f or v elocity initializa tion in ANSY S Fluen t is r elative. If the solution in most of y our domain is r otating , using the r elative option ma y be better than using the absolut e option. 4.After you ar e sa tisfied with the Initial Values displa yed in the task page , you c an click the Initializ e butt on to initializ e the flo w field . If solution da ta alr eady exist (tha t is, if you ha ve alr eady performed some c alcu- lations or initializ ed the solution), you must c onfir m tha t it is OK t o overwrite those da ta. 37.9.1.1. Saving and R esetting Initial Values When y ou initializ e the solution b y click ing on Initializ e, the initial v alues will also b e sa ved; should you need t o reinitializ e the solution la ter, you will find the c orrect values in the task page when y ou reop en it. If you acciden tally selec t the wr ong z one fr om the Comput e fr om list or manually set a v alue inc or- rectly, you c an use the Reset butt on t o reset all fields t o their “saved” values . 37.9.2. Patching Values in S elec ted C ells Onc e you ha ve initializ ed (or c alcula ted) the en tire flo w field , you ma y pa tch diff erent values f or par- ticular v ariables in to diff erent cells. If you ha ve multiple fluid z ones , for e xample , you ma y want to patch a diff erent temp erature in each one .You c an also cho ose t o pa tch a cust om field func tion (defined using the Custom F ield F unction C alcula tor D ialog Box (p.3797 )) inst ead of a c onstan t value . If you ar e pa tching v elocities , you c an indic ate whether the sp ecified v alues ar e absolut e velocities or velocities r elative to the c ell z one’s velocity. All pa tching op erations ar e performed with the Patch Dialog Box (p.3622 ) (Figur e 37.14: The P atch D ialog Box (p.2608 )). Solution → Initializa tion Patch... Solution → Initializa tion → Patch... 2607Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Initializing the S olutionFigur e 37.14: The P atch D ialo g Box 1.Selec t the v ariable t o be pa tched in the Variable list. Note For sp ecies tr ansp ort cases with a single phase flo w, you c an selec t boundar y sp ecies to be displa yed in the Variable list using the Selec t Boundar y Species dialo g box (see Figur e 15.3: The S elec t Boundar y Species D ialog Box (p.1623 )) tha t can b e acc essed b y click ing the Species butt on in the Solution Initializa tion task page . 2.In the Zones t o Patch and/or Regist ers t o Patch lists , cho ose the z one(s) and/or r egist er(s) f or which y ou want to pa tch a v alue f or the selec ted v ariable . Imp ortant When a shell z one has b een cr eated (tha t is, by enabling shell c onduc tion f or a w all and running the c alcula tion), the name of the shell z one will b e list ed in the Zones t o Patch list as shell : , wher e < wall-name > is the name of the w all in which shell conduc tion has b een enabled . Only t emp erature can b e pa tched in to the c ells of a shell, and the same v alue or field func tion will b e pa tched in to every layer of the shell. 3.If you w ant to pa tch a c onstan t value , simply en ter tha t value in the Value field . If you w ant to pa tch a previously-defined field func tion, enable the Use F ield F unc tion option and selec t the appr opriate func tion in the Field F unc tion list. 4.If you selec ted a v elocity in the Variable list, and y our pr oblem in volves mo ving r eference frames or sliding meshes , indic ate whether the pa tched v elocities ar e absolut e velocities or v elocities r elative to the motion of each c ell z one b y selec ting Absolut e or Rela tive to Cell Z one under Referenc e Frame . (If no z one motion o ccurs in the pr oblem, the t wo options ar e equiv alen t.) The default r eference frame f or velocity pa tching in ANSY S Fluen t is r elative. If the solution in most of y our domain is r otating , using the relative option ma y be better than using the absolut e option. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2608Using the S olver5.Click the Patch butt on t o up date the flo w-field da ta. (Note tha t pa tching will ha ve no eff ect on the it eration or time-st ep c oun t.) Imp ortant If you apply a pa tch when setting up an ANSY S Fluen t simula tion fr om ANSY S Workbench, the pa tch will not b e aut oma tically p erformed dur ing futur e aut oma tic solution up dates from Workbench. If you need t o apply the pa tch each time the solution is up dated fr om Workbench, you c an do so b y adding the t ext command /solve/patch (with appr opriate argumen ts) t o the Original S ettings command list in the Case M odific ation tab of the Automa tic S olution Initializa tion and C ase M odific ation dialo g box. See Automa tic Ini- tializa tion of the S olution and C ase M odific ation (p.2664 ) in this manual and Case M odific ation Strategies with F luen t and Workbench in the Fluen t in Workbench U ser's G uide for mor e details on aut oma tic c ase mo dific ation. 37.9.2.1. Using R egist ers The abilit y to pa tch v alues in c ell r egist ers giv es y ou the fle xibilit y to pa tch diff erent values within a single c ell z one . For e xample , you ma y want to pa tch a c ertain v alue f or temp erature only in fluid cells with a par ticular r ange of c oncentrations f or one sp ecies .You c an cr eate a c ell r egist er (basic ally a list of c ells) using the c ell r egist ers f eature (Using C ell R egist ers (p.2758 )).These func tions allo w you to mar k cells based on ph ysical lo cation, cell v olume , gradien t or iso value of a par ticular v ariable (using a field v ariable r egist er), and other par amet ers. Onc e you ha ve created a r egist er, you c an patch v alues in it as descr ibed ab ove. 37.9.2.2. Using F ield F unc tions By defining y our o wn field func tion using the Custom F ield F unction C alcula tor D ialog Box (p.3797 ), you c an pa tch a non-c onstan t value in selec ted c ells. For e xample , you ma y want to pa tch v arying species mass fr actions thr oughout a fluid r egion. To use this f eature, simply cr eate the func tion as descr ibed in Custom F ield F unctions (p.3038 ), and then p erform the func tion-pa tching op eration in the Patch D ialog Box (p.3622 ), as descr ibed ab ove. 37.9.2.3. Using P atching L ater in the S olution P rocess Since pa tching aff ects only the v ariables f or which y ou cho ose t o change the v alue , leaving the r est of the flo w field in tact, you c an use it la ter in the solution pr ocess without losing c alcula ted da ta. (Initializa tion, on the other hand , resets all da ta to the initial v alues). For e xample , you migh t want to star t a c ombustion c alcula tion fr om a c old-flo w solution. You c an simply r ead in (or c alcula te) the cold-flo w da ta, patch a high t emp erature in the appr opriate cells, and c ontinue the c alcula tion. Patching c an also b e useful when y ou ar e solving a pr oblem using a st ep-b y-step t echnique , as de- scribed in Step-b y-Step S olution P rocesses (p.2692 ). 37.10. Full M ultigr id (FMG) Initializa tion For man y comple x flo w pr oblems such as those f ound in r otating machiner y, or flo ws in e xpanding or spiral duc ts, flow convergenc e can b e acc elerated if a b etter initial solution is used a t the star t of the calcula tion. The F ull M ultigr id initializa tion (FMG initializa tion) c an pr ovide this initial and appr oxima te solution a t a minimum c ost t o the o verall c omputa tional e xpense . 2609Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Full M ultigr id (FMG) Initializa tionFor mor e inf ormation ab out FMG initializa tion, see Overview of FMG Initializa tion in the Fluent Theor y Guide . The limita tions tha t apply t o the FMG Initializa tion c an b e found in Limita tions of FMG Initializa tion in the Fluent Theor y Guide . For additional inf ormation, see the f ollowing sec tions: 37.10.1. Steps in U sing FMG Initializa tion 37.10.2. Convergenc e Strategies f or FMG Initializa tion 37.10.1. Steps in U sing FMG Initializa tion You c an acc ess the FMG initializa tion pr ocedur e using the t ext user in terface (TUI) onc e the standar d flow initializa tion is p erformed (see Full-A pproxima tion S torage (F AS) M ultigr id in the Theor y Guide ) or if v alid flo w da ta is a vailable (tha t is, through r eading a da ta file). To cust omiz e the FMG initializa tion, type the f ollowing c ommand : solve → initialize → set-fmg-initialization You will b e ask ed t o en ter: •The numb er of multigr id le vels f or the FMG it eration (the default is 5). Imp ortant For small c ases (100, 000 c ells or less), it is r ecommended tha t you lo wer the numb er of multigr id le vels t o 3 or 4. •For each le vel of multigr id, you will b e ask ed t o en ter the r esidual r educ tion (the default v alue is 0.001 ), and the numb er of c ycles p er le vel (the defaults a t each le vel ar e 10,10,50,100 ,500 , and 500 ). In gen- eral, you should p erform mor e iterations on c oarse le vels than fine le vels. Level 0 is the finest le vel, which represen ts the or iginal mesh. •FMG it eration C ourant-numb er (the default is 0.75 ).This will b e the CFL v alue tha t the F AS multigr id will use f or the FMG initializa tion. •Enabling v erbose mo de (the default is no). By enabling this option, you will b e able t o monit or the c onver- genc e at each le vel. Imp ortant If you do not cust omiz e the FMG settings , then the default v alues will b e used . To perform the FMG initializa tion, type the f ollowing c ommand : solve → initialize → fmg-initialization When y ou ar e pr ompt ed t o Enable FMG initialization? [no] , type yes . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2610Using the S olverWhen v erbose mo de is selec ted and the FMG initializa tion is b eing used , ANSY S Fluen t will first output the multigr id le vel inf ormation f ollowed b y convergenc e hist ory for the F AS multigr id cycle on each level.The nor maliz ed r esidual v alue is pr inted af ter ten F AS c ycles or when the numb er of F AS c ycles is reached .The output will indic ate when c onvergenc e is r eached on each le vel and when the solution is being in terpolated t o the ne xt level. 37.10.2. Convergenc e Strategies f or FMG Initializa tion When setting the FMG initializa tion par amet ers, you should c onsider p erforming mor e iterations on the c oarse le vels than on the fine le vels. However, rememb er tha t the pur pose of FMG initializa tion is to obtain a go od initial solution a t a lo w cost. You should tr y to avoid unr easonable c onvergenc e tol- erance tha t will mak e the FMG initializa tion e xpensiv e. Turn on the v erbose mo de t o help y ou det ermine if the flo w is c onverging as e xpected dur ing the FMG it erations . If the solution is not c onverging t o the desir ed t oler ance, consider incr easing the numb er of F AS multigr id cycles a t each le vel. If the solution is div erging dur ing the F AS c ycles, then consider lo wering the FMG it eration C ourant numb er sinc e the default v alue is pr obably t oo aggr essiv e and is lik ely c ausing the solution t o div erge. For turbulen t flo ws, it is v ery imp ortant to first p erform standar d initializa tion with pr oper and r ealistic values of the turbulenc e variables (f or e xample and ).This c an b e done b y computing the a verage values based on the c onditions defined a t the inflo w b oundar y or a t all b oundar y zones .Then, you can pr oceed with FMG initializa tion. Unrealistic initializa tion of turbulenc e variables ma y cause c onver- genc e difficulties dur ing the first f ew it erations on the fine mesh, ther eby nullifying the b enefit of FMG initializa tion. 37.11. Hybrid Initializa tion Hybrid initializa tion is y et another initializa tion metho d in ANSY S Fluen t.The other initializa tion metho ds are standar d initializa tion and FMG initializa tion. Hybrid initializa tion is a c ollec tion of r ecip es and boundar y interpolation metho ds. It solv es Laplac e's equa tion t o det ermine the v elocity and pr essur e fields . All other v ariables , such as t emp erature, turbulenc e, species fr actions , and v olume fr actions , will be aut oma tically pa tched based on domain a veraged v alues or a par ticular in terpolation r ecip e. For mor e inf ormation ab out h ybrid initializa tion, see Hybrid Initializa tion in the Theor y Guide . For additional inf ormation, see the f ollowing sec tions: 37.11.1. Steps in U sing H ybrid Initializa tion 37.11.2. Solution S trategies f or H ybrid Initializa tion 37.11.1. Steps in U sing H ybrid Initializa tion The default initializa tion metho d for single phase st eady-sta te flo ws is the Hybr id Initializa tion metho d. Note For other flo w types, such as multiphase or unst eady simula tions , the default initializa tion metho d is the Standar d Initializa tion metho d. However b oth initializa tion metho ds ar e available f or use in all flo w conditions and t ypes. 2611Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Hybrid Initializa tionTo use Hybr id Initializa tion , go t o the Solution Initializa tion Task P age (p.3620 ) (Figur e 37.15: The Solution Initializa tion Task P age f or H ybrid Initializa tion (p.2612 )) wher e you will selec t Hybr id Initializ- ation . Solution → Initializa tion Figur e 37.15: The S olution Initializa tion Task P age f or H ybr id Initializa tion Note In most c ases , you need not do an ything mor e than click the Initializ e butt on. However, should y ou decide t o mo dify the default settings f or the h ybrid initializa tion metho d, click More Settings .... If you click More Settings ..., the Hybr id Initializa tion dialo g box (Figur e 37.16: The H ybrid Initializa tion Dialog Box (p.2613 )) will op en. A host of settings tha t control the Hybr id Initializa tion strategy will b e available f or y ou t o adjust. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2612Using the S olverFigur e 37.16: The H ybr id Initializa tion D ialo g Box You c an mak e adjustmen ts in thr ee diff erent areas: •Gener al S ettings tab: –Numb er of I terations uses a default v alue of 10. This is the numb er of it erations tha t will b e performed while solving the Laplac e equa tions t o initializ e the v elocity and pr essur e. In gener al, you do not need to change the numb er of it erations . However, for comple x and highly cur ved geometr ies, if the default numb er of it erations is not enough t o reach the c onvergenc e toler ance of 1e-06 and the flo w fields ar e not t o your lik ing, then y ou ma y want to incr ease the numb er of it erations and r e-initializ e the flo w. –Explicit U nder-Relaxa tion F actor uses a default v alue of 1. This v alue will b e used while solving the Laplac e equa tion t o initializ e the v elocity and pr essur e. In gener al, you do not need t o change the e xplicit under-r elaxa tion fac tor. However, for some c ases , wher e the sc alar r esiduals ar e oscilla ting and sho wing difficult y reaching the c onvergenc e toler ance of 1e-06, you ma y want to re-initializ e the flo w by reducing the under-r elaxa tion fac tor.You ma y also w ant to incr ease the numb er of it erations t o pr oduce a smo oth initializa tion field f or the v elocity and pr essur e. –Referenc e Frame is set t o Rela tive to Cell Z one by default. If your pr oblem in volves mo ving r eference frames or sliding meshes , indic ate whether the initial v elocities ar e absolut e velocities or v elocities r elative to the motion of each c ell z one b y selec ting Absolut e or Rela tive to Cell Z one . If no z one motion o ccurs in the pr oblem, the t wo options ar e equiv alen t. If the solution in most of y our domain is r otating , using the r elative option ma y be better than using the absolut e option. –Initializa tion Options allo ws you t o include the f ollowing options: 2613Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Hybrid Initializa tion→Use S pecified Initial P ressur e on Inlets if you w ant the sp ecified pr essur e for Supersonic/Initializa tion Gauge P ressur e at the inlet b oundar ies t o be used f or solving the Laplac e equa tion f or the pr essur e. Other wise , ANSY S Fluen t uses a pr edet ermined r ecip e to det ermine the initial pr essur e field , as descr ibed in Hybrid Initializa tion of the Theor y Guide . →Use E xternal-A ero Favorable S ettings if you w ant to ha ve the v elocity potential pa tched with a linear value t o help acc elerate convergenc e of Scalar E qua tion–0 and t o obtain a b etter guess of the v elocity field f or e xternal-aer o pr oblems , such as flo w over wings , airfoils, or aut omobiles . →Maintain C onstan t Velocity M agnitude if you w ant to use the flo w dir ection obtained fr om solving the v elocity potential ( Scalar E qua tion–0 ), while main taining a c onstan t velocity magnitude throughout the c omputa tional domain. This option is helpful in some inc ompr essible e xternal flo w problems , porous media pr oblems , or if ther e are nar row channels wher e lar ge undesir able v elocities can b e reached . •Turbulenc e Settings tab uses b y default the domain a veraged v alues f or the turbulenc e par amet ers. If you w ant to use v ariable turbulenc e par amet ers y ou c an deselec t the Average Turbulen t Paramet ers check b ox.When this option is disabled , then it c alcula tes the turbulen t par amet ers, such as k inetic ener gy and dissipa tion ener gy, using lo cal flo w par amet ers. •Species S ettings tab will b y default initializ e sec ondar y sp ecies with z ero mass or mole fr actions . If you want to sp ecify the appr opriate value f or the sp ecies , you will need t o enable Specify S pecies P aramet ers. Note tha t only the b oundar y sp ecies tha t you ha ve selec ted in the Selec t Boundar y Species dialo g box app ear in the list (see Figur e 15.3: The S elec t Boundar y Species D ialog Box (p.1623 )).You c an add or r emo ve a sp ecies using the Selec t Boundar y Species tha t can b e acc essed b y click ing Species in the Solution Initializa tion task page . 37.11.2. Solution S trategies f or H ybrid Initializa tion In gener al, you do not need t o mak e an y extra adjustmen ts to the h ybrid initializa tion default settings . However, if the h ybrid initializa tion is not pr oducing the initial field t o your lik ing, then y ou c an pla y with the v arious options a vailable in the Hybr id Initializa tion dialo g box (descr ibed in Steps in U sing Hybrid Initializa tion (p.2611 )), or y ou c an also use the pa tching option in addition t o the Hybr id Initial- ization . For e xample , if y ou ar e solving a user-defined sc alar, then h ybrid initializa tion will initializ e them with a v alue of z ero. However, you c an sp ecify the v alue with which y ou w ant to pa tch. Note You c an also use a user-defined func tion t o initializ e the flo w or c ertain flo w variable in conjunc tion with h ybrid initializa tion. Standar d Initializa tion is the r ecommended initializa tion metho d for p orous media simula tions .The default Hybr id initializa tion metho d do es not acc oun t for the p orous media pr operties, and dep ending on b oundar y conditions , ma y pr oduce an unr ealistic initial v elocity field . For p orous media simula tions , the Hybr id initializa tion metho d can only b e used with the Maintain C onstan t Velocity M agnitude option. 37.12. Performing S tead y-State Calcula tions For st eady-sta te calcula tions , you will r equest the star t of the solution pr ocess using the Run C alcula tion Task P age (p.3640 ) (Figur e 37.17: The R un C alcula tion Task P age (p.2615 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2614Using the S olverSolution → Run C alcula tion Figur e 37.17: The R un C alcula tion Task P age Here, you will supply the numb er of additional it erations t o be performed in the Numb er of I terations field . (For unst eady calcula tion inputs , see User Inputs f or Time-D ependen t Problems (p.2627 )). If no c al- cula tions ha ve been p erformed y et, ANSY S Fluen t will b egin c alcula tions star ting a t iteration 1, using the initial solution. If you ar e star ting fr om cur rent solution da ta, ANSY S Fluen t will b egin a t the last it- eration p erformed , using the cur rent solution da ta as its star ting p oint. By default , ANSY S Fluen t will up date the c onvergenc e monit ors (descr ibed in Monit oring S olution Convergenc e (p.2646 )) after each it eration. If you incr ease the Rep orting In terval from the default of 1 2615Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Performing S teady-State Calcula tionsyou c an get r eports less fr equen tly. For e xample , if y ou set the Rep orting In terval to 2, the monit ors will pr int or plot r eports at every other it eration. Note tha t the Rep orting In terval also sp ecifies ho w often ANSY S Fluen t should check if the solution is c onverged . For e xample , if y our solution c onverges after 40 it erations , but y our Rep orting In terval is set t o 50, ANSY S Fluen t will c ontinue the c alcula tion for an e xtra 10 it erations b efore check ing f or (and finding) c onvergenc e. When y ou click the Calcula te butt on, ANSY S Fluen t will b egin t o calcula te.While the c alcula tion is in progress, a pr ogress bar will app ear a t the b ottom of the F luen t windo w. For st eady-sta te simula tions , click ing the Stop butt on ne xt to the pr ogress bar will in terrupt the c alcula tion a t the ear liest saf e stopping p oint after the cur rent iteration. Alternatively, you c an t ype Ctrl+c in the c onsole .Transien t simula tions ha ve additional options f or st opping , as descr ibed in User Inputs f or Time-D ependen t Problems (p.2627 ). For additional inf ormation, see the f ollowing sec tions: 37.12.1. Updating UDF P rofiles 37.12.2. Resetting D ata 37.12.3. Data Sampling f or Steady Statistics 37.12.1. Updating UDF P rofiles If you ha ve used a user-defined func tion (UDF) t o define an y boundar y conditions y ou c an c ontrol the frequenc y with which the func tion is up dated b y mo difying the v alue of the Profile U pdate In terval. If Profile U pdate In terval is set t o , the func tion will b e up dated af ter e very iterations . By default , the Profile U pdate In terval is set t o 1. You migh t want to incr ease this v alue if y our pr ofile computa tion is e xpensiv e. See the Fluen t Customiza tion M anual for details ab out cr eating and using UDFs . 37.12.2. Resetting D ata After y ou ha ve performed some it erations , if y ou decide t o star t over again fr om the first it eration (f or example , after mak ing some changes t o the pr oblem setup), you c an r einitializ e the solution using the Solution Initializa tion Task P age (p.3620 ), as descr ibed in Initializing the En tire Flow Field U sing S tandar d Initializa tion (p.2605 ). 37.12.3. Data S ampling f or S tead y Statistics While notionally st eady, some simula tions t end t o exhibit oscilla tory or quasi-tr ansien t behavior.While in pr inciple , these simula tions c ould b e solv ed as unst eady flo w pr oblems and ac tually r esolv e the transien t behavior, this is of ten not pr actical and sometimes unnec essar y.Data S ampling f or S tead y Statistics is useful under such cir cumstanc es and helps gener ate averaged r esults and tr ends tha t are better b ehaved and useful in flo w pr edic tions . If you enable the Data S ampling f or S tead y Statistics option in the Run C alcula tion Task P age (p.3640 ) (see Performing S teady-State Calcula tions (p.2614 ) for details), ANSY S Fluen t will c omput e the it eration average (mean) of the instan taneous v alues , the r oot-mean-squar e, and the r oot-mean-squar e-er rors of those quan tities and cust om field func tions tha t are enabled/selec ted in the Sampling Options Dialog Box (p.3659 ). The Sampled I terations field displa ys the it erations o ver which da ta has b een sampled f or the p ost- processing of the mean, RMS, and RMSE v alues . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2616Using the S olverUse the f ollowing st eps t o ha ve ANSY S Fluen t ga ther da ta for st eady sta tistics while c alcula ting: 1.(Optional) C reate a cust om field func tion f or each of the v ariables of in terest f or st eady sta tistics p ostpr o- cessing (f or e xample ,P*|V| ) using the Custom F ield F unction C alcula tor D ialog Box (p.3797 ).Note that you do not need t o cr eate cust om field func tions f or the flo w shear str esses , flow heat flux es, wall statistics , or discr ete phase v ariables , as these v ariables ar e available f or selec tion lat er. User D efined → Field F unc tions → Custom... 2.Enable Data S ampling f or S tead y Statistics in the Run C alcula tion task page . Solution → Run C alcula tion → Data S ampling f or S tead y Statistics Enabling this option allo ws you t o displa y and r eport the mean and the r oot-mean-squar e-er ror (RMSE) v alues . The mean, root-mean-squar e (RMS), and r oot-mean-squar e-er ror (RMSE) v alues f or solution v ariables will b e available in the Stead y Statistics ... categor y (or the Stead y DPM S tatistics ... categor y for discr ete phase quan tities) of the v ariable selec tion dr op-do wn list tha t app ears in p ostpr ocessing dialo g boxes. For e xample , in the Contours dialo g box, you c ould selec t Stead y Statistics ... and RMSE-uns-cust om-func tion-0 for the Contours of drop-do wn lists t o displa y the r oot-mean-squar e- errors of a cust om field func tion named uns-cust om-func tion-0 . 3.Specify the Sampling In terval. The Sampled I terations field displa ys the it erations o ver which the da ta has b een sampled f or the postpr ocessing of the mean and RMSE v alues . 4.Selec t the v ariables f or sta tistics sampling thr ough the Sampling Options D ialog Box (p.3659 ). Solution → Run C alcula tion → Sampling Options ... 5.Initializ e the flo w sta tistics . Solution → Initializa tion → Reset S tatistics Note that y ou c an also r eset the flo w statistics af ter y ou ha ve some data f or the st ead y statistics . For example , if y ou p erform 10 it erations with Data S ampling for St eady Statistics enabled , check the results , and c ontinue with the c alculation f or another 10 it erations , the st ead y statistics will include the data gather ed in the first 10 it erations , unless y ou r einitializ e the flo w statistics . 37.13. Performing P seudo Transien t Calcula tions For st eady-sta te calcula tions , when using the pr essur e-based c oupled solv er or the densit y-based implicit solv er, you ha ve the option of solving y our flo w in a pseudo-tr ansien t fashion. The pseudo tr ansien t under-r elaxa tion metho d is a f orm of implicit under-r elaxa tion, descr ibed in Pseudo Transien t Under- Relaxa tion in the Theor y Guide . To apply the pseudo tr ansien t under-r elaxa tion metho d, perform the f ollowing: 1.Selec t the Densit y-Based solv er or the Pressur e-Based solv er. 2617Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Performing P seudo Transien t Calcula tionsSetup → Gener al 2.Go to the Solution M etho ds task page ( Figur e 37.18: The S olution M etho ds Task P age (p.2619 )). Solution → Metho ds a.If you ar e using the pr essur e-based solv er, the Coupled scheme under Pressur e-Velocity Coupling is the default. b.If you ar e using the densit y-based solv er, cho ose the Implicit scheme under Formula tion . c.Pseudo Transien t is the default option. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2618Using the S olverFigur e 37.18: The S olution M etho ds Task P age 37.13.1. Setting P seudo Transien t Explicit Relaxa tion F actors In addition t o pseudo tr ansien t under-r elaxa tion, you c an sp ecify an e xplicit under-r elaxa tion of the equa tion t o control the up date of c omput ed v ariables a t each it eration (see Pseudo Transien t Under- Relaxa tion in the Theor y Guide). The default v alues of under-r elaxa tion par amet ers f or all v ariables ar e set t o values tha t work well for most of the c ases . It is go od pr actice to star t a c alcula tion with the default under-r elaxa tion par amet ers. If your c ase e xhibits div ergenc e or the r esiduals c ontinue t o incr ease after a f ew it erations , then y ou should r educ e the under-r elaxa tion fac tors. 2619Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Performing P seudo Transien t Calcula tions37.13.1.1. User Inputs You c an mo dify the pseudo tr ansien t under-r elaxa tion fac tors in the Solution C ontrols Task P age (p.3606 ) (Figur e 37.19: The S olution C ontrols Task P age f or the P seudo Transien t Runs (p.2620 )). Solution → Controls Figur e 37.19: The S olution C ontrols Task P age f or the P seudo Transien t Runs You c an set the under-r elaxa tion fac tor for each equa tion in the field ne xt to its name under Pseudo Transien t Explicit Relaxa tion F actors. Imp ortant If you ar e using the pr essur e-based solv er, all equa tions will ha ve an asso ciated under-r e- laxa tion fac tor (see Under-R elaxa tion of E qua tions in the Theor y Guide ). If you ar e using the densit y-based solv er, only those equa tions tha t are solv ed sequen tially (see Densit y- Based S olver in the Theor y Guide ) will ha ve under-r elaxa tion fac tors. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2620Using the S olverIf you change under-r elaxa tion fac tors, but y ou then w ant to retur n to ANSY S Fluen t’s default settings , you c an click the Default butt on. 37.13.2. Setting S olution C ontrols f or the P seudo Transien t Metho d To ha ve fur ther c ontrol o ver the par amet ers f or each individual equa tion, when solving a pseudo transien t case, you c an go t o the Expert tab , in the Advanc ed S olution C ontrols dialo g box (Fig- ure 37.20: The A dvanced S olution C ontrols D ialog Box for the P seudo Transien t Metho d (p.2622 )). Note that all equa tions , except f or flo w equa tions (tha t is pr essur e and momen tum) will b e list ed. Gener ally, you will not need t o visit this dialo g box to en ter equa tion-sp ecific solution par amet ers. However, it may help in c ases wher e a par ticular equa tion is giving c onvergenc e pr oblems . Here, ANSY S Fluen t allows two options t o impr ove convergenc e: 1.Specify a time sc ale fac tor for the equa tion sp ecific time st ep in lieu of using a unif orm global pseudo time st ep.This sc aling fac tor sc ales the pseudo time st ep emplo yed f or the flo w equa tions sp ecified in the Run C alcula tion task page (see Solving P seudo-T ransien t Flow (p.2622 )). 2.Use the standar d steady-sta te metho d by tur ning off pseudo tr ansien t for tha t par ticular equa tion. Here, the c orresponding under-r elaxa tion fac tor to be emplo yed with tha t equa tion ma y be sp ecified . The default v alues of under-r elaxa tion par amet ers f or all v ariables ar e set t o values tha t work well for most of the c ases . The default setting will ha ve the pseudo tr ansien t metho d tur ned on f or all equa tions with the c orres- ponding time sc ale fac tor set t o unit y, except when one of the c ombustion mo dels is used .When the pseudo tr ansien t metho d is enabled In c ombustion c ases the sp ecies , enthalp y, and c ombustion v ariable equa tions will only use the pseudo tr ansien t metho d if it is manually enabled in the Expert tab . As well, when using the pr emix ed, par tially-pr emix ed, or PDF c ombustion mo dels , the ener gy equa tion will only use the pseudo tr ansien t metho d if it is manually enabled in the Expert tab . By default , all user-defined sc alars (UDS) ha ve pseudo tr ansien t metho d disabled .This is b ecause the physical par amet ers of the UDS and the appr opriate time sc ale ar e not k nown t o the solv er b efore starting the c alcula tion. You c an manually enable pseudo tr ansien t metho d for UDS under the Expert tab in the Advanced S olution C ontrols D ialog Box (p.3611 ). Solution → Controls Advanc ed... 2621Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Performing P seudo Transien t Calcula tionsFigur e 37.20: The A dvanc ed S olution C ontrols D ialo g Box for the P seudo Transien t Metho d Specify the equa tion-sp ecific st eady-sta te solution metho d for a par ticular equa tion (if needed) b y enabling or disabling the pseudo tr ansien t metho d using the On/O ff check b ox ne xt to the equa tion. The dialo g box then allo ws either sp ecific ation of a pseudo Time Sc ale F actor or Under-Relaxa tion Factor for tha t par ticular equa tion based on the check b ox setting . Note For multiphase flo ws, the pseudo tr ansien t expert options f or the v olume fr action equa tion are available only when it is solv ed in segr egated fashion. It is not a vailable when the Coupled with Volume F ractions option is enabled in the Solution M etho ds task page (see Selec ting the P ressur e-Velocity Coupling M etho d (p.2264 ) for inf ormation ab out this setting). 37.13.3. Solving P seudo-T ransien t Flow With the Pseudo Transien t option enabled in the Solution M etho ds task page , you c an no w sp ecify the time st ep f or the Fluid Z one and/or the Solid Z one under Pseudo Transien t Settings in the Run Calcula tion task page ( Figur e 37.21: The R un C alcula tion Task P age f or the U ser-S pecified P seudo Transien t Time S tep M etho d (p.2623 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2622Using the S olverSolution → Run C alcula tion Figur e 37.21: The R un C alcula tion Task P age f or the U ser-S pecified P seudo Transien t Time S tep Metho d 1.Selec t the Time S tep M etho d for the Fluid Time Sc ale. a.If you cho ose User-S pecified , you will en ter the Pseudo Time S tep, which is used f or e very equa tion unless the equa tion sp ecific time st ep is used f or a par ticular equa tion, as men tioned in Setting S olution C ontrols f or the P seudo Transien t Metho d (p.2621 ).Typic ally, the time sc ale size should b e relevant to the global time sc ale of the flo w, for e xample: wher e is a r epresen tative length sc ale f or the geometr y (such as chor d length). 2623Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Performing P seudo Transien t Calcula tionsb.If you use the default Automa tic metho d (see Figur e 37.22: The R un C alcula tion Task P age f or the Automa tic P seudo Transien t Option (p.2625 )), the pseudo time st ep is c alcula ted in ternally and used for each equa tion list ed, unless the equa tion has a time st ep sp ecified as not ed in Setting S olution Controls f or the P seudo Transien t Metho d (p.2621 ).The aut oma tic time sc ale is c alcula ted fr om time scales estima ted f or v arious ph ysics ac tive in the simula tion. For mor e inf ormation, refer to Automa tic Pseudo Transien t Time S tep in the Theor y Guide . You c an c ontrol the c onvergenc e pr ocess b y adjusting the aut oma tic pseudo time st ep v alue using the Time Sc ale F actor field , which simply sc ales the c alcula ted time st ep b y the sp ecified value .The aut oma tic time sc ale c alcula tion is of ten somewha t conser vative, and incr easing the Time Sc ale F actor to 3 or 10 can of ten incr ease the c onvergenc e rate. Less c ommonly , you may need t o reduc e its v alue t o 0.3 or 0.1 for b etter convergenc e. Alternatively, you c an also fine-tune the aut oma tic pseudo time st ep b y cho osing the Length Scale M etho d used t o calcula te its v alue .The f ollowing options ar e available in the dr op-do wn list: •Conser vative: (default) uses the cub e root of the mesh v olume f or 3D c ases and squar e root of ar ea for 2D c ases . •Aggr essiv e: uses the maximum geometr y extent, leading t o a lar ger time st ep siz e than Conser vative. •User-S pecified allo ws you t o dir ectly c ontrol the Length Sc ale.This metho d is par ticular ly useful in pr oblems tha t ha ve a sp ecific length sc ale tha t is difficult t o det ermine fr om the o verall geometr y of the pr oblem. For e xample , in the c ase of flo w over an air foil, the appr opriate length sc ale w ould b e the length of the air foil inst ead of the length sc ale calcula ted based on the geometr y of the en tire domain. You c an sp ecify the Verb osit y.This is an in teger v alue of 0, 1, or 2. The default v alue is 0. A value of 1 pr ints the pseudo time st ep siz e. A v alue of 2 pr ints additional details ab out the c al- cula tion. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2624Using the S olverFigur e 37.22: The R un C alcula tion Task P age f or the A utoma tic P seudo Transien t Option 2.Selec t the Time S tep M etho d for the Solid Time Sc ale. Note Solid Time Sc ale only app ears in the in terface when a solid z one is pr esen t in the domain or when the Energy equa tion is enabled along with Porous Z one or the Solidific ation & M elting mo del. 2625Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Performing P seudo Transien t Calcula tionsa.If you cho ose User-S pecified , you will en ter the Pseudo Time S tep, which is used wher e the Solid Time Sc ale is needed (tha t is, solid z ones , porous z ones , and/or solidific ation/melting model). b.If you cho ose Automa tic, which is the default metho d, the pseudo time st ep is c alcula ted in ternally as descr ibed in Automa tic P seudo Transien t Time S tep in the Theor y Guide . Specify a Time Sc ale Factor to control/adjust the pseudo time st ep obtained fr om the aut oma tically c alcula ted Solid Time Scale. 3.Continue setting up y our solution as y ou w ould a st eady-sta te run, as descr ibed in Performing S teady- State Calcula tions (p.2614 ). 37.14. Performing Time-D ependen t Calcula tions ANSY S Fluen t can solv e the c onser vation equa tions in a time-dep enden t manner , to simula te a wide variety of time-dep enden t phenomena, such as •vortex shedding and other time-p eriodic phenomena •compr essible filling and empt ying pr oblems •transien t hea t conduc tion •transien t chemic al mixing and r eactions Figur e 37.23: Time-D ependen t Calcula tion of Vortex Shedding (t=36.6 sec) (p.2626 ) and Figur e 37.24: Time- Dependen t Calcula tion of Vortex Shedding (t=41.6 sec) (p.2627 ) illustr ate the time-dep enden t vortex shedding flo w pa ttern in the w ake of a c ylinder . Figur e 37.23: Time-D ependen t Calcula tion of Vortex Shedding (t=36.6 sec) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2626Using the S olverFigur e 37.24: Time-D ependen t Calcula tion of Vortex Shedding (t=41.6 sec) Enabling time dep endenc e is sometimes useful when a ttempting t o solv e steady-sta te pr oblems tha t tend t oward instabilit y (for e xample , natural convection pr oblems in which the R ayleigh numb er is close to the tr ansition r egion). It is p ossible in man y cases t o reach a st eady-sta te solution b y integrating the time-dep enden t equa tions . For details ab out t emp oral discr etiza tion, see Temp oral D iscretiza tion in the Theor y Guide . For additional inf ormation, see the f ollowing sec tions: 37.14.1. User Inputs f or Time-D ependen t Problems 37.14.2. CFL-B ased Time S tepping 37.14.3. Error-B ased Time S tepping 37.14.4. Multiphase-S pecific Time S tepping 37.14.5. Postpr ocessing f or Time-D ependen t Problems 37.14.1. User Inputs f or Time-D ependen t Problems To solv e a tr ansien t problem, you will f ollow the pr ocedur e outlined b elow: 1.Enable the Transien t option in the Gener al task page ( Figur e 37.25: The G ener al Task P age f or a Transien t Calcula tion (p.2628 )). Setup → Gener al 2627Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Performing Time-D ependen t Calcula tionsFigur e 37.25: The G ener al Task P age f or a Transien t Calcula tion 2.Define all r elevant mo dels and b oundar y conditions . Note tha t an y boundar y conditions sp ecified using user-defined func tions c an b e made t o vary in time . See the Fluen t Customiza tion M anual for details . 3.Specify the desir ed par amet ers in the Solution M etho ds task page ( Figur e 37.26: The S olution M etho ds Task P age f or a Transien t Calcula tion (p.2629 )). Solution → Metho ds Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2628Using the S olverFigur e 37.26: The S olution M etho ds Task P age f or a Transien t Calcula tion If you ar e using the pr essur e-based solv er, selec t PISO from the Scheme drop-do wn list in the Pressur e-Velocity Coupling group b ox.To incr ease the sp eed of the c alcula tions , you ma y need 2629Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Performing Time-D ependen t Calcula tionsto mo dify the par amet ers r elated t o the PISO scheme fr om their default v alues . See PISO (p.2571 ) for mor e inf ormation ab out the optimal use of the PISO algor ithm. Imp ortant If you ar e using the LES turbulenc e mo del with small time st eps, the PISO scheme ma y be too computa tionally e xpensiv e. It is ther efore recommended tha t you selec t SIMPLE or SIMPLEC inst ead of PISO . Imp ortant It is b est t o selec t the Coupled pressur e-velocity coupling scheme if y ou ar e using lar ge time st eps t o solv e your tr ansien t flo w, or if y ou ha ve a p oor qualit y mesh. Next, specify the desir ed Transien t Formula tion .The First Or der Implicit formula tion is sufficien t for most pr oblems . If you need impr oved accur acy, you c an either use Second Or der Implicit or Bounded S econd Or der Implicit .The Bounded S econd Or der Implicit formula tion w ould pr ovide better stabilit y, sinc e time discr etiza tion w ould alw ays ensur e the b ounds f or v ariables , if a vailable . Imp ortant Note tha t while the Bounded S econd Or der Implicit formula tion pr ovides the same accur acy as the Second Or der Implicit formula tion, it ac tually pr ovides b etter stabilit y. Imp ortant The Bounded S econd Or der Implicit formula tion is a vailable only f or the pr essur e- based solv er, and not f or the densit y-based solv er. Imp ortant When using Second Or der Implicit or Bounded S econd Or der Implicit formula tion for a d ynamic mesh, do not r un a ser ies of simula tions in which y ou v ary the time st ep size. Doing so cr eates an er ror tha t reduc es with a r educ tion of the time st ep jump . The Explicit formula tion (a vailable only f or the densit y-based solv er) is used pr imar ily to captur e the tr ansien t behavior of mo ving w aves, such as sho cks. For details , see Temp oral D iscretiza tion in the Theor y Guide . When using the pr essur e-based solv er, you ha ve the additional options of selec ting Non-I terative Time A dvanc emen t and Frozen F lux F ormula tion for y our time-dep enden t flo w calcula tions (see Time-A dvancemen t Algor ithm and Steady-State Iterative Algor ithm in the Theor y Guide , respectively). Note tha t the la tter option is only a vailable f or single-phase tr ansien t problems tha t do not use a moving/def orming mesh mo del. 4.For tr ansien t cases tha t use the densit y-based e xplicit f ormula tion, you c an use the f ollowing t ext command t o easily swit ch t o a t wo-stage R unge-K utta scheme f or the time in tegration. This scheme results in fast er calcula tions than the default thr ee- or f our-stage R unge-K utta scheme (esp ecially Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2630Using the S olverfor laminar flo ws), though the r educ ed stabilit y range ma y requir e changes t o the setup as descr ibed below. > solve/set/fast-transient-settings/rk2 Enable two-stage Runge-Kutta scheme? [no] yes This t ext command will set the Numb er of S tages to 2 in the Multi-S tage tab of the Advanced Solution C ontrols D ialog Box (p.3611 ), with c oefficien ts of 0.5 and 1. For fur ther details ab out these settings , see Setting M ulti-S tage Time-S tepping P aramet ers (p.2601 ). If your solution div erges with this scheme , you c an a ttempt the c alcula tion again with a lo wer C ourant numb er (t ypic ally less than 1) and , for implicit time st epping , a higher v alue f or the maximum numb er of it erations p er time st ep; if nec essar y, you c an use the rk2 text command again t o easily disable the t wo-stage Runge-K utta scheme and r evert back t o the default multi-stage scheme f or y our time-st epping scheme (summar ized in Summar y of the D ensit y-Based S olver in the Fluent Theor y Guide ). 5.(optional) I f you ar e using the e xplicit tr ansien t formula tion with sp ecified C ourant numb er or if you ar e using an y of the adaptiv e time st epping metho ds (descr ibed in a la ter st ep) it is r ecommen- ded tha t you enable the pr inting of the cur rent time (f or the e xplicit tr ansien t formula tion) or the current time st ep siz e (for the adaptiv e time st epping metho d) a t each it eration, using Fig- ure 37.32: Report File for 'flo w-time', 'delta-time', and 'it ers-p er-timest ep' (p.2656 ). Solution → Monit ors → Statistic Edit... Make sur e tha t the desir ed it em is selec ted fr om the Statistics selec tion list ( time for the cur rent time or delta_time for the cur rent time st ep siz e) and enable the Print option. When ANSY S Flu- ent prints the r esiduals t o the c onsole a t each it eration, it will include a c olumn with the cur rent time or the cur rent time st ep siz e. 6.(optional) U se the Drag R eport Definition D ialog Box (p.3808 ), the Lift Report Definition D ialog Box (p.3845 ), the Momen t Report Definition D ialog Box (p.3864 ), or the Surface Report Definition D ialog Box (p.3930 ) to monit or (and/or sa ve to a file) time-v arying f orce coefficien t values or a r eport of a field v ariable or func tion on a sur face as it changes with time . See Monit oring S olution C onvergenc e (p.2646 ) for details . 7.Set the initial c onditions (a t time ) using the Solution Initializa tion task page . Solution → Initializa tion You c an also r ead in a st eady-sta te da ta file t o set the initial c onditions . File → Read → Data... 8.Use the Autosa ve dialo g box to sp ecify the file name and fr equenc y with which c ase and da ta files should be sa ved dur ing the solution pr ocess.To op en the Autosa ve dialo g box, click the Edit... butt on ne xt to Autosa ve Every in the Calcula tion A ctivities task page . Solution → Calcula tion A ctivities → Autosa ve On See Automa tic S aving of C ase and D ata Files (p.591) for details ab out aut oma tic file sa ving . The Calcula tion A ctivities task page also allo ws you t o export solution and par ticle hist ory da ta during the tr ansien t calcula tion. See Exporting D ata D uring a Transien t Calcula tion (p.627) for details . 2631Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Performing Time-D ependen t Calcula tionsIf you w ant to cr eate a gr aphic al anima tion of the solution o ver time , you c an use Figur e 37.41: The Anima tion D efinition D ialog Box (p.2671 ) to set up the gr aphic al displa ys tha t you w ant to use in the anima tion. See Anima ting the S olution (p.2670 ) for details . You ma y also w ant to request aut oma tic e xecution of other c ommands using the Execut e Commands Dialog Box (p.3637 ). See Executing C ommands D uring the C alcula tion (p.2660 ) for details . 9.Specify time-dep enden t solution par amet ers and star t the c alcula tion as descr ibed b elow for the implicit and e xplicit tr ansien t formula tions: •If you ha ve chosen the First Or der Implicit ,Second Or der Implicit , or Bounded S econd Or der Implicit formula tion, the pr ocedur e is as f ollows: a.Open the Run C alcula tion Task P age (p.3640 ) (see Figur e 37.27: The R un C alcula tion Task P age f or Implicit Transien t Calcula tions (p.2633 )). Solution → Run C alcula tion Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2632Using the S olverFigur e 37.27: The R un C alcula tion Task P age f or Implicit Transien t Calcula tions b.If you w ant the time st eps t o remain a fix ed siz e thr oughout the simula tion, selec t Fixed from the Type drop-do wn list , and then selec t one of the f ollowing fr om the Metho d drop-do wn list: –User-S pecified : with this metho d, you will sp ecify the desir ed Numb er of Time S teps and the Time S tep S ize. 2633Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Performing Time-D ependen t Calcula tions–Period-B ased or Frequenc y-Based : these metho ds ar e convenien t when setting up unst eady turb omachiner y cases or an y case tha t exhibits tr ansien t periodic b ehavior.They allo w you t o define the setup in t erms of the Period or Frequenc y, the Time S teps p er P eriod, and the Total Periods, and then F luen t will aut oma tically set an appr opriate Time S tep S ize and Numb er of Time S teps. When ANSY S Fluen t solv es the time-dep enden t equa tions using the implicit f ormula tion, multiple it erations ma y be nec essar y at each time st ep, so y ou c an sp ecify a v alue f or the Max I terations/T ime S tep you w ould lik e to allo w. If the c onvergenc e cr iteria ar e met before this numb er of it erations is p erformed , the solution will ad vance to the ne xt time step. The time st ep siz e is the magnitude of . Since the ANSY S Fluen t formula tion is fully implicit , ther e is no stabilit y criterion tha t must b e met in det ermining . However, to mo del tr ansien t phenomena pr operly, it is nec essar y to set at least one or der of magnitude smaller than the smallest time c onstan t in the sy stem b eing mo deled . A go od w ay to judge the choic e of is to obser ve the numb er of it erations ANSY S Fluen t needs t o converge a t each time st ep. The ideal numb er of it erations p er time st ep is 5–10. If ANSY S Fluen t needs substan tially mor e, the time st ep is t oo lar ge. If ANSY S Fluen t needs only a f ew it erations p er time st ep, should b e incr eased . Frequen tly a time-dep enden t problem has a v ery fast “startup” transien t tha t dec ays rapidly .Therefore, it is of ten wise t o cho ose a c onser vatively small for the first 5–10 time st eps. ma y then b e gr adually incr eased as the c alcula tion pr oceeds . For time-p eriodic c alcula tions , you should cho ose the time st ep based on the time sc ale of the p eriodicit y. For a r otor/sta tor mo del, for e xample , you migh t want 20 time st eps b etween each blade passing . For v ortex shedding , you migh t want 20 st eps p er p eriod. To verify tha t your choic e for was pr oper af ter the c alcula tion is c omplet e, you c an plot contours of the C ourant numb er within the domain. To do so , selec t Velocity... and Cell Convective Cour ant Numb er from the Contours of drop-do wn lists in the Contours dialo g box. For a stable , efficien t calcula tion, the C ourant numb er should not e xceed a v alue of 20–40 in most sensitiv e transien t regions of the domain. Note The Period-B ased and Frequenc y-Based metho ds ar e not a vailable f or in-c ylinder dynamic mesh simula tions; inst ead, the User-S pecified metho d must b e used , and the time st ep siz e will b e comput ed based on the cr ank shaf t sp eed and the crank angle st ep siz e. c.If you w ant ANSY S Fluen t to mo dify the siz e of the time st ep as the c alcula tion pr oceeds , selec t Adaptiv e from the Type drop-do wn list , and then selec t one of the f ollowing fr om the Metho d drop-do wn list: –CFL-B ased : with this metho d, ANSY S Fluen t will mo dify the siz e of the time st ep as the calcula tion pr oceeds such tha t the C ourant–Friedr ichs–L ewy (CFL) c ondition is sa tisfied . See CFL-B ased Time S tepping (p.2640 ) for details . –Error-B ased : with this metho d, the time st ep is mo dified b y ANSY S Fluen t based on the sp ecified truncation Error Toler anc e. See Error-B ased Time S tepping (p.2642 ) for details . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2634Using the S olver–Multiphase-S pecific : with this metho d, the time st ep is mo dified b y ANSY S Fluen t based on the convective time sc ale ( Global C our ant Numb er).The time st ep siz e calcula tion dep ends on the mesh densit y and v elocity in in terfacial c ells.This metho d is a vailable f or all multiphase mo dels using implicit or e xplicit v olume fr action f ormula tion, except f or the w et st eam mo del. See Mul- tiphase-S pecific Time S tepping (p.2643 ) for details .While this metho d and the CFL-B ased appr oach both use a C ourant numb er, the y diff er in tha t the Multiphase-S pecific metho d considers the interface regions when c omputing the time st ep siz e, wher eas the CFL-B ased metho d is based on a global time mar ching appr oach. Note The Adaptiv e type is not a vailable f or simula tions tha t use the ac oustic mo del and/or the str uctural mo del. It is also una vailable f or in-c ylinder d ynamic mesh simula tions; in this c ase, the fix ed User-S pecified metho d must b e used , and the time st ep siz e will b e comput ed based on the cr ank shaf t sp eed and the cr ank angle st ep siz e. Next, mak e a selec tion fr om the Duration S pecific ation M etho d drop-do wn list in or der t o specify the w ay in which y ou will define the c alcula tion dur ation. The dur ation c an b e defined by the t otal time , the t otal numb er of time st eps, the incr emen tal time , or the numb er of incremen tal time st eps. In this c ontext, "total" indic ates tha t Fluen t will c onsider the amoun t of time / st eps tha t ha ve alr eady been solv ed and st op appr opriately, wher eas "incr emen tal" indic ates tha t the solution will pr oceed f or a sp ecified amoun t of time / st eps r egar dless of wha t has pr eviously b een c alcula ted. It is a go od idea t o perform a f ew fix ed-siz e time st eps b efore swit ching t o the adaptiv e time stepping . Sometimes spur ious discr etiza tion er rors c an b e asso ciated with an impulsiv e star t in time .These er rors ar e dissipa ted dur ing the first f ew time st eps, but the y can ad versely affect the adaptiv e time st epping and r esult in e xtremely small time st eps a t the b eginning of the c alcula tion. You c an sp ecify the Numb er of F ixed Time S teps tha t should b e performed before the siz e of the time st ep star ts to change .The siz e of the fix ed time st ep is the v alue specified f or Initial Time S tep S ize; this v alue must fall b etween the minimum and maximum time st ep siz es. For a b etter star tup, it should b e chosen such tha t the C ourant numb er initially remains close t o 1 or y our sp ecified v alue (whiche ver is lo wer). Note tha t if y ou initializ e the solution f or a pr eviously r un c ase with adaptiv e time st epping , then ANSY S Fluen t will use the time st ep siz e sa ved in the c ase. Imp ortant When the solution t ends t o exhibit inc omplet e convergenc e for the Error-B ased metho d, rather than incr easing the time st ep siz e or k eeping the same time st ep size in the ne xt step, ANSY S Fluen t reduc es the time st ep siz e for the ne xt time step (mak ing sur e tha t the time st ep siz e do es not go b elow the sp ecified minimum time st ep siz e). When ANSY S Fluen t solv es the time-dep enden t equa tions using the implicit f ormula tion, multiple it erations ma y be nec essar y at each time st ep, so y ou c an sp ecify a v alue f or the Max I terations/T ime S tep you w ould lik e to allo w. If the c onvergenc e cr iteria ar e met b efore this numb er of it erations is p erformed , the solution will ad vance to the ne xt time st ep.You can also define the Time S tep S ize Update In terval, which sp ecifies the numb er of time steps tha t will pass b efore the time st ep siz e is up dated f or adaptiv e time st epping metho ds. 2635Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Performing Time-D ependen t Calcula tionsFinally , click the Settings ... butt on and c omplet e the setup f or the adaptiv e time st epping metho d in the Adaptiv e Time S tepping D ialog Box (p.3648 ), setting the minimum / maximum time st ep siz es and change fac tors. Tip If you need y our simula tion t o end e xactly a t your sp ecified t otal or incr emen tal time , input smaller and smaller v alues f or the minimum time st ep siz e un til this condition is met. d.If you w ant to define y our o wn adaptiv e time st epping metho d rather than use one of the Adaptiv e types descr ibed pr eviously , you c an cr eate a user-defined func tion f or y our metho d using the DEFINE_DELTAT macr o. After y ou ha ve compiled or in terpreted it , you c an selec t User-D efined F unc tion from the Type drop-do wn list and then selec t it fr om the User- Defined Time S tep drop-do wn list. You c an then define the dur ation metho d and time / numb er of time st eps, as descr ibed pr eviously f or the Adaptiv e types. See the Fluen t Customiza tion M anual for details ab out cr eating and using user-defined func tions . e.(optional) You c an impr ove the c onvergenc e of the tr ansien t calcula tions b y enabling the Extrapolate Variables option in the Run C alcula tion Task P age (p.3640 ).This option instr ucts ANSY S Fluen t to predic t the solution v ariable v alues f or the ne xt time st ep using a Taylor ser ies e xpansion, and then inputs tha t predic ted v alue as an initial guess f or the inner it erations of the cur rent time st ep. As a result , the absolut e residual le vels ar e lowered. Note tha t the Extrapolate Variables option is not a vailable if y ou ar e emplo ying either the NITA scheme with the pr essur e-based solv er or the e xplicit f ormula tion with the densit y- based solv er. Imp ortant If you use the Extrapolate Variables option when mo deling an inc ompr essible flow with the densit y-based solv er, it is r ecommended tha t you disable the e xtra- polation of pr essur e values . After y ou ha ve enabled the Extrapolate Variables option, type the f ollowing t ext command in the c onsole: > solve/set/extrapolate-eqn-vars/pressure Extrapolate Pressure? [yes] no f.To view details ab out the time ad vancemen t of the simula tion, enable the Rep ort Simula tion S tatus option in the Options group b ox.While this option is enabled (b efore, after, or dur ing a c alcula tion), the Simula tion S tatus D ialog Box (p.3649 ) will b e op en and r eporting inf ormation. g.(optional) I f you w ant ANSY S Fluen t to ga ther da ta for time sta tistics (tha t is, time-a veraged , root- mean-squar e, and r oot-mean-squar e-er ror v alues f or solution v ariables) dur ing the c alcula tion, follow these st eps: i.Create a cust om field func tion f or the each of the v ariables f or which y ou w ant to post- process unst eady sta tistics (f or e xample , P*|V|), using the Custom F ield F unc tion C alcu- Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2636Using the S olverlator. For detailed instr uctions , see Creating a C ustom F ield F unction (p.3039 ). Note tha t you do not need t o tak e the e xtra step of cr eating cust om field func tions f or the flo w shear str esses , flow hea t flux es, wall sta tistics , or discr ete phase v ariables as ther e ar e options f or selec ting these v ariables dir ectly in a la ter st ep. Paramet ers & C ustomiza tion → Custom F ield F unc tions New... Imp ortant The maximum numb er of cust om field func tions tha t can b e calcula ted and postpr ocessed f or unst eady sta tistics is 50. ii.Enable the Data S ampling f or Time S tatistics option in the Run C alcula tion Task P age (p.3640 ). Solution → Run C alcula tion → Data S ampling f or Time S tatistics Enabling this option will allo w you t o displa y and r eport the mean, the r oot-mean-squar e (RMS), and the r oot-mean-squar e-er ror (RMSE) v alues , as descr ibed in Postpr ocessing f or Time-D ependen t Problems (p.2645 ). To sp ecify the sampling in terval, enter a v alue f or Sampling In terval. The Sampled Time displa ys the time p eriod over which da ta has b een sampled f or the postpr ocessing of the mean, RMS, and RMSE v alues . For most quan tities , as long as the time st ep siz e has b een c onstan t, dividing this b y the time st ep siz e yields the numb er of da ta sets tha t ha ve been c ollec ted. However, special c onsider ation is r equir ed in the case of discr ete phase quan tities . As not ed in Reporting of U nsteady DPM S tatistics (p.2052 ), sampling of DPM quan tities o ccurs only when par cels pass thr ough a c ell, not nec essar ily at each sp ecified sampling in terval.Therefore, the numb er of samples of the DPM quan tities tak en dur ing the sampled time p eriod is st ored in the separ ate postpr ocessing variable ,Accum DPM P arcels in C ell. If the time st ep siz e is v aried, every contribution of da ta sets sampled is aut oma tically w eigh ted b y the cur rent time st ep siz e. To selec t the v ariables (which ma y be represen ted as cust om field func tions) f or which you w ant to collec t sta tistics , click the Sampling Options ... butt on and mak e selec tions from the Sampling Options dialo g box tha t op ens ( Figur e 37.28: The S ampling Options Dialog Box (p.2638 )). Note tha t no cust om field func tions ar e selec ted b y default. Solution → Run C alcula tion → Sampling Options ... 2637Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Performing Time-D ependen t Calcula tionsFigur e 37.28: The S ampling Options D ialo g Box Imp ortant Note tha t ga ther ing da ta for time sta tistics is not meaning ful inside a mo ving cell z one (f or e xample , a sliding z one in a sliding mesh pr oblem, a mo ving zone in a d ynamic mesh pr oblem). iii.Initializ e the flo w sta tistics . Solution → Initializa tion Reset S tatistics Note tha t you c an also r eset the flo w sta tistics af ter y ou ha ve ga ther ed some da ta for time sta tistics . If you p erform, say, 10 time st eps with the Data S ampling f or Time S tat- istics option enabled , check the r esults , and then c ontinue the c alcula tion f or 10 mor e time st eps, the time sta tistics will include the da ta ga ther ed in the first 10 time st eps unless you r einitializ e the flo w sta tistics . h.Click the Calcula te butt on. As it c alcula tes a solution, ANSY S Fluen t will pr int the cur rent time a t the end of each time st ep. •If you cho ose the Explicit transien t formula tion,y ou ha ve two input options a vailable f or sp ecifying the tr ansien t solution ad vancemen t: you c an sp ecify the tr ansien t ad vancemen t either dir ectly b y sp e- cifying a time st ep siz e ( ) or indir ectly via en tering a C ourant numb er value ( ) in the Solution Controls task page .The st eps f or these t wo options ar e as f ollows: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2638Using the S olver–If the default option Specified Time S tep is enabled in the Solution C ontrols task page , you will b e requir ed t o sp ecify the time ad vancemen t settings in the Run C alcula tion task page: you need t o define the time st epping as either a Fixed or User-D efined F unc tion type (as descr ibed pr eviously for the implicit f ormula tions) and click the Calcula te butt on. Note The stabilit y of an e xplicit f ormula tion is limit ed b y the C ourant-Fredrichs-L ewy condition. Fluen t checks the sp ecified time st ep against the stabilit y limit. The sta- bilit y limit is the maximum allo wable time st ep siz e calcula ted based on in Equa tion 37.1 (p.2639 ).The stabilit y limit is also the minimum of all lo cal time st eps in the domain. If the sp ecified time st ep siz e is lar ger than the maximum allo wable time st ep, Fluen t displa ys a w arning dur ing the c alcula tion. –If you disable the Specified Time S tep option, you will b e requir ed t o sp ecify the Cour ant Numb er in the Solution C ontrols task page .Then y ou c an define the Numb er of Time S teps in the Run Calcula tion task page and click Calcula te. In this option the ( ) value is used t o calcula te the time step siz e ( ) using Equa tion 37.1 (p.2639 ): (37.1) wher e, is the v olume of the c ell, is the fac e ar ea, and is the maximum lo cal eigen- value defined in Equa tion 28.81 in the Fluent Theor y Guide . When y ou click the Calcula te butt on, ANSY S Fluen t will b egin t o calcula te.While the c alcula tion is in pr ogress, a pr ogress bar will app ear a t the b ottom of the F luen t windo w. For tr ansien t simula- tions , click ing the butt ons ne xt to the pr ogress bar will in terrupt the c alcula tion a t the ear liest saf e stopping p oint: you c an cho ose t o stop the c alcula tion a t the end of either the cur rent iteration or cur rent time st ep. Alternatively, you c an t ype Ctrl+c in the c onsole: a single instanc e will st op the c alcula tion a t the end of the cur rent time st ep, wher eas t yping it t wice will st op it a t the end of the cur rent iteration. You c an acc ess the inf ormation sa ved in a da ta file , which includes a standar d set of quan tities that were comput ed dur ing the c alcula tion, by click ing the Data F ile Q uan tities ... butt on. More information ab out this f eature is a vailable in Setting D ata File Q uan tities (p.651). 10.Save the final da ta file (and c ase file , if you ha ve mo dified it) so tha t you c an c ontinue the tr ansien t calcu- lation la ter, if desir ed. File → Write → Data... 2639Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Performing Time-D ependen t Calcula tions37.14.1.1. Additional Inputs The pr ocedur es for setting the r eporting in terval, updating user-defined func tion pr ofiles , interrupting iterations , and r esetting da ta ar e the same as those f or st eady-sta te calcula tions . See Performing Steady-State Calcula tions (p.2614 ) for details . Imp ortant If you ar e using a user-defined func tion in y our time-dep enden t calcula tion, not e tha t, in addition t o being up dated af ter e very iterations (wher e is the v alue of the Profile Update In terval), the func tion will also b e up dated a t the first it eration of each time st ep. 37.14.2. CFL-B ased Time S tepping As men tioned in User Inputs f or Time-D ependen t Problems (p.2627 ), it is p ossible t o ha ve the siz e of the time st ep change as the c alcula tion pr oceeds such tha t the C ourant–Friedr ichs–L ewy (CFL) c ondition is sa tisfied . Note tha t the time st ep siz e will only v ary if the solution of the flo w equa tion is enabled , and it is a c onvection-dominan t flo w.This sec tion pr ovides a br ief descr iption of the algor ithm tha t ANSY S Fluen t uses t o comput e the time st ep siz e, as w ell as an e xplana tion of par amet ers tha t you can set t o control the CFL-based time st epping . Imp ortant CFL-based time st epping is a vailable only with the pr essur e-based and densit y-based implicit formula tions; it c annot b e used with the densit y-based e xplicit f ormula tion. Also, it c annot be used with multiphase flo ws, the in-c ylinder d ynamic mesh option, the ac oustic mo del, and/or the str uctural mo del, nor is it a vailable with the sec ond-or der implicit f ormula tion if the fix ed time st ep f ormula tion is selec ted thr ough the solve/set/second-order- time-options text command or thr ough the enabling of a d ynamic mesh. Note If ther e ar e other time sc ales c ontrolling the ph ysics of pr oblem (sur face tension time sc ale, meshing-dr iven time sc ales f or mesh def ormation, and so on), then the CFL-based time stepping is not a go od choic e. 37.14.2.1. The CFL -Based Time St epping A lgorithm For a c ell , a lo cal time st ep siz e is c alcula ted based on the C ourant numb er ( ) tha t you ha ve defined as par t of the settings: (37.2) wher e Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2640Using the S olver(37.3) (37.4) and = C ell v olume = C onstan t fac tor = In viscid sp ectral radii = Viscous sp ectral radii = Sur face ar ea v ector = N umb er of c ell fac es The global time st ep siz e is then defined as the minimum lo cal time st ep siz e in the domain, provided that it is within the minimum and maximum v alues tha t you ha ve defined as par t of the settings . 37.14.2.2. Specifying P aramet ers for CFL -Based Time St epping For tr ansien t flo ws, when y ou selec t Adaptiv e for the Type and CFL-B ased for the Metho d in the Run C alcula tion task page , you c an then set the time st epping par amet ers as descr ibed in User Inputs for Time-D ependen t Problems (p.2627 ).The f ollowing pr ovides fur ther details tha t are sp ecific f or the CFL-based time st epping . In the Run C alcula tion task page: Cour ant Numb er is in Equa tion 37.2 (p.2640 ), which r epresen ts the r atio of the time st ep siz e to the char acteristic time taken for the fluid t o cross a c ontrol volume . For convection-dominan t and/or w ave pr opaga tion pr oblems , it is r ecommended tha t you set this close t o 1 in or der t o obtain mor e accur ate results . Incr easing it will result in an incr ease of the time st ep siz e and c onsequen tly a fast er tr ansien t simula tion; however, this may ha ve a nega tive impac t on the c onvergenc e, stabilit y, and accur acy of y our tr ansien t simula tion. Initial Time S tep S ize is used f or the first time st ep and then f or as man y subsequen t steps as sp ecified in the Numb er of F ixed Time S teps field .This v alue must fall b etween the minimum and maximum time st ep siz es. It should b e chosen such tha t the Cour ant Numb er initially r emains close t o 1 or y our sp ecified v alue (whiche ver is lower) f or a b etter star tup. Note tha t if y ou initializ e the solution f or a pr eviously r un c ase with adaptiv e time st epping , then ANSY S Fluen t will use the time st ep siz e sa ved in the c ase file . In the Adaptiv e Time S tepping dialo g box: 2641Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Performing Time-D ependen t Calcula tionsMinimum / M aximum S tep C hange F actor limit the degr ee to which the time st ep siz e can change a t each time st ep. Limiting the change r esults in a smo other c alcula tion of the time st ep siz e, esp ecially when high-fr equenc y noise is pr esen t in the solution. The time st ep change fac tor is c omput ed as the r atio b etween the cur rent time st ep and the previous time st ep. When cho osing the v alues , it is gener ally not r ecommended t o allo w lar ge v ariation in time st ep size due t o stabilit y consider ations .This is esp ecially tr ue when the time st ep siz e is r amping up . It is r ecommended tha t you use a minimum time st ep siz e fac tor in the r ange of 0.5 t o 0.75, and a maximum time st ep change fac tor in the r ange of 1.2 t o 2. The default v alues of 0.5 and 2, re- spectively, provide a smo oth tr ansition of the time st ep siz e. 37.14.3. Error-B ased Time S tepping As men tioned in User Inputs f or Time-D ependen t Problems (p.2627 ), it is p ossible t o ha ve the siz e of the time st ep change as the c alcula tion pr oceeds based on the tr uncation er ror toler ance.This sec tion provides a br ief descr iption of the algor ithm tha t ANSY S Fluen t uses t o comput e the time st ep siz e, as w ell as an e xplana tion of par amet ers tha t you c an set t o control the er ror-based time st epping . Imp ortant Error-based time st epping is a vailable only with the pr essur e-based and densit y-based im- plicit f ormula tions; it c annot b e used with the densit y-based e xplicit f ormula tion. It cannot be used with sec ond-or der time in tegration and/or the in-c ylinder d ynamic mesh option; it is also una vailable with E uler-E uler multiphase mo dels (descr ibed in Approaches t o M ul- tiphase M odeling in the Theor y Guide ), with the e xception of the E uler ian mo del when the implicit v olume fr action f ormula tion is enabled . 37.14.3.1. The E rror-Based Time St epping A lgorithm The aut oma tic det ermina tion of the time st ep siz e is based on the estima tion of the tr uncation er ror asso ciated with the time in tegration scheme . If the tr uncation er ror is smaller than a sp ecified t oler ance, the siz e of the time st ep is incr eased; if the tr uncation er ror is gr eater, the time st ep siz e is decr eased . An estima tion of the tr uncation er ror c an b e obtained b y using a pr edic tor-c orrector type of algor ithm [44] (p.4007 ) in asso ciation with the time in tegration scheme . At each time st ep, a pr edic ted solution can b e obtained using a c omputa tionally ine xpensiv e explicit metho d: forward Euler f or the first-or der unst eady formula tion. This pr edic ted solution is used as an initial c ondition f or the time st ep, and the c orrection is c omput ed using the nonlinear it erations asso ciated with the implicit (pr essur e-based or densit y-based) f ormula tion. The nor m of the diff erence between the pr edic ted and c orrected solutions is used as a measur e of the tr uncation er ror. By compar ing the tr uncation er ror with the desir ed le vel of accur acy (tha t is, the tr uncation er ror toler ance), ANSY S Fluen t is able t o adjust the time st ep siz e by incr easing it or decr easing it. In cases wher e the tr uncation er ror remains ab ove the sp ecified t oler ance, ANSY S Fluen t will tr y to meet the t oler ance within 5 a ttempts . If this t oler ance is met or the 5 a ttempts ar e complet ed, then the it eration mo ves on t o the ne xt time st ep. An explicit scheme is used t o pr edic t the solution a t each time st ep, then the e xplicit pr edic tion is c orrected with an implicit scheme .The tr uncation er ror, which is a func tion of the diff erence between the pr edic ted and c orrected solutions a t a sp ecific time is used t o calcula te the ne xt time st ep. However, if the c alcula ted tr uncation er ror is gr eater than the toler ance limit , we ha ve the option of r everting fr om the cur rently p erformed it eration, which is Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2642Using the S olvermoving fr om the th step t o th step, and p erforming the it eration with a smaller time st ep. Since the tr uncation er ror is pr oportional t o the time st ep, decr easing the time st ep r educ es the tr uncation error.This c an b e done un til the tr uncation er ror go es b elow the t oler ance limit. 37.14.3.2. Specifying P aramet ers for E rror-Based Time St epping For tr ansien t flo ws, when y ou selec t Adaptiv e for the Type and Error-B ased for the Metho d in the Run C alcula tion task page , you c an then set the time st epping par amet ers as descr ibed in User Inputs for Time-D ependen t Problems (p.2627 ).The f ollowing pr ovides fur ther details tha t are sp ecific f or the error-based time st epping . In the Run C alcula tion task page: Error Toler anc e specifies the thr eshold v alue t o which the c omput ed tr uncation er ror is c ompar ed. Incr easing this v alue will lead t o an incr ease in the siz e of the time st ep and a r educ tion in the accur acy of the solution. De- creasing it will lead t o a r educ tion in the siz e of the time st ep and an incr ease in the solution accur acy, although the c alcula tion will r equir e mor e computa tional time . For most c ases , the default v alue of 0.01 is acc eptable . Initial Time S tep S ize is used f or the first time st ep and then f or as man y subsequen t steps as sp ecified in the Numb er of F ixed Time S teps field .This v alue must fall b etween the minimum and maximum time st ep siz es. It should b e chosen such tha t the C ourant numb er initially r emains close t o 1 f or a b etter star tup. Note tha t if y ou initializ e the solution f or a pr eviously r un c ase with adaptiv e time st epping , then ANSY S Fluen t will use the time st ep siz e sa ved in the c ase file . In the Adaptiv e Time S tepping dialo g box: Minimum/M aximum S tep C hange F actor limit the degr ee to which the time st ep siz e can change a t each time st ep. Limiting the change r esults in a smo other c alcula tion of the time st ep siz e, esp ecially when high-fr equenc y noise is pr esen t in the solution. If the time st ep change fac tor, , is comput ed as the r atio b etween the sp ecified tr uncation error toler ance and the c omput ed tr uncation er ror, the siz e of time st ep is comput ed as f ollows: •If , is incr eased t o meet the desir ed t oler ance. •If , is incr eased , but its maximum p ossible v alue is . •If , is unchanged . •If , is decr eased . 37.14.4. Multiphase-S pecific Time S tepping Multiphase-sp ecific time st epping is supp orted f or all multiphase mo dels using implicit or e xplicit volume fr action f ormula tion, except f or the w et st eam mo del. It is not supp orted with the in-c ylinder dynamic mesh option, the ac oustic mo del, and/or the str uctural mo del. 2643Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Performing Time-D ependen t Calcula tionsMultiphase-sp ecific time st epping is based on the c onvective time sc ale (C ourant based), in which the time-st ep-siz e calcula tion dep ends on the mesh densit y and v elocity in in terfacial c ells. Note If ther e ar e other time sc ales c ontrolling the ph ysics of pr oblem (sur face tension time sc ale, meshing-dr iven time sc ales f or mesh def ormation, and so on), then the C ourant-based time scale is not a go od choic e. 37.14.4.1. The Multiphase-Sp ecific Time St epping A lgorithm The global time st ep is changed in the f ollowing manner : (37.5) wher e is the global C ourant numb er, and the r atio is c alcula ted f or each cell. ANSY S Fluen t tak es the maximum of this r atio t o calcula te the global time st ep. 37.14.4.2. Specifying P aramet ers for Multiphase-Sp ecific Time St epping For tr ansien t flo ws, when y ou selec t Adaptiv e for the Type and Multiphase-S pecific for the Metho d in the Run C alcula tion task page , you c an then set the time st epping par amet ers as descr ibed in User Inputs f or Time-D ependen t Problems (p.2627 ).The f ollowing pr ovides fur ther details tha t are specific f or the multiphase-sp ecific time st epping . In the Run C alcula tion task page: Global C our ant Numb er is the r atio of the time st ep siz e to the char acteristic time tak en for the fluid t o cross a c ontrol volume . To calcula te the C ourant numb er, ANSY S Fluen t uses a flux-based definition wher e, in the r egion near the fluid in terface, ANSY S Fluen t divides the v olume of each c ell b y the sum of the out going flux es.The resulting time r epresen ts the time it w ould tak e for the fluid t o empt y out of the c ell.The smallest such time is used as the char acteristic time of tr ansit f or a fluid elemen t acr oss a c ontrol volume .The default value f or Global C our ant Numb er is 2, which means tha t the estima ted time st ep siz e is t wice the char acteristic time of tr ansit. The optimal v alue f or Global C our ant Numb er is dep enden t on a sp ecific c ase.The gener al re- commenda tions on cho osing an appr opriate value f or G lobal C ourant Numb er ar e summar ized below. •Explicit v olume fr action f ormula tion –For accur acy of an instan taneous-time solution, the default v alue of 2 is r ecommended . –For a time-a veraged solution, you c an use higher v alues , but not lar ger than 5. •Implicit v olume fr action f ormula tion –For an instan taneous-time solution, you c an set Global C our ant Numb er to 2 (r ecommended) with the first or der time f ormula tion and t o a higher v alue (up t o 5) with the sec ond or der time f ormula- tion. –For a time-a veraged solution, you c an use e ven higher v alues (up t o 20). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2644Using the S olverInitial Time S tep S ize is used f or the first time st ep and then f or as man y subsequen t steps as sp ecified in the Numb er of F ixed Time S teps field .This v alue must fall b etween the minimum and maximum time st ep siz es. It should b e chosen such tha t the Global C our ant Numb er initially r emains close t o 1 or y our sp ecified v alue (whiche ver is lo wer) f or a b etter star tup. Note tha t if y ou initializ e the solution f or a pr eviously r un c ase with adaptiv e time st epping , then ANSY S Fluen t will use the time st ep siz e sa ved in the c ase file . In the Adaptiv e Time S tepping dialo g box: Minimum / M aximum S tep C hange F actor limit the degr ee to which the time st ep siz e can change a t each time st ep. Limiting the change r esults in a smo other c alcula tion of the time st ep siz e, esp ecially when high-fr equenc y noise is pr esen t in the solution. The time st ep change fac tor is c omput ed as the r atio b etween the cur rent time st ep and the previous time st ep. When cho osing the v alues , it is gener ally not r ecommended t o allo w lar ge v ariation in time st ep size due t o stabilit y consider ations .This is esp ecially tr ue when time st ep siz e is r amping up . It is recommended tha t you use a minimum time st ep siz e fac tor in the r ange of 0.5 t o 0.8 and a maximum time st ep change fac tor in the r ange of 1.2 t o 1.5. The default v alues of 0.8 and 1.2, respectively, provide a smo oth tr ansition of the time st ep siz e. 37.14.5. Postpr ocessing f or Time-D ependen t Problems The p ostpr ocessing of time-dep enden t da ta is similar t o tha t for st eady-sta te da ta, with all gr aphic al and alphanumer ic commands a vailable .You c an r ead a da ta file tha t was sa ved a t an y point in the calcula tion (b y you or with the aut osave option) t o restore the da ta a t an y of the time le vels tha t were saved. File → Read → Data... ANSY S Fluen t will lab el an y subsequen t graphic al or alphanumer ic output with the time v alue of the current da ta set. If you sa ve da ta fr om the f orce or sur face report definitions t o files (see st ep 5 in User Inputs f or Time- Dependen t Problems (p.2627 )), you c an r ead these files back in and plot them t o see a time hist ory of the monit ored quan tity.Figur e 37.29: Lift Coefficien t Plot f or a Time-P eriodic S olution (p.2646 ) sho ws a sample plot gener ated in this w ay. 2645Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Performing Time-D ependen t Calcula tionsFigur e 37.29: Lift Coefficien t Plot f or a Time-P eriodic S olution If you enable the Data S ampling f or Time S tatistics option in the Run C alcula tion Task P age (p.3640 ) (see Performing Time-D ependen t Calcula tions (p.2626 ) for details), ANSY S Fluen t will c omput e the time average (mean) of the instan taneous v alues , the r oot-mean-squar e, and the r oot-mean-squar e-er rors of those quan tities and cust om field func tions tha t are enabled/selec ted in the Sampling Options dialo g box. The Sampled Time displa ys the time o ver which da ta has b een sampled f or the p ostpr ocessing of the mean, RMS, and RMSE v alues . For most quan tities , as long as the time st ep siz e has b een c onstan t, dividing this b y the time st ep siz e yields the numb er of da ta sets tha t ha ve been c ollec ted. However, special c onsider ation is r equir ed In the c ase of discr ete phase quan tities . As not ed in Reporting of Unsteady DPM S tatistics (p.2052 ), sampling of DPM quan tities o ccurs only when par cels pass thr ough a cell, not nec essar ily a t each sp ecified sampling in terval.Therefore, the numb er of samples of the DPM quan tities tak en dur ing the sampled time p eriod is st ored in the separ ate postpr ocessing v ariable , Accum DPM P arcels in C ell. If the time st ep siz e is v aried, every contribution of da ta sets sampled is automa tically w eigh ted b y the cur rent time st ep siz e. The mean, root-mean-squar e(RMS), and r oot-mean-squar e-er ror (RMSE) v alues f or solution v ariables will b e available in the Unstead y Statistics ... categor y (or the Unstead y DPM S tatistics ... categor y for discr ete phase quan tities) of the v ariable selec tion dr op-do wn list tha t app ears in p ostpr ocessing dialo g boxes. For e xample , in the Contours dialo g box, you c ould selec t Unstead y Statistics ... and RMSE-uns-cust om-func ton-0 for the Contours of drop-do wn lists in or der t o displa y the r oot-mean- squar e-er rors of a cust om field func tion named uns-cust om-func ton-0 . 37.15. Monit oring S olution C onvergenc e During the solution pr ocess y ou c an monit or the c onvergenc e dynamic ally b y check ing r esiduals , stat- istics , force values , sur face in tegrals, and v olume in tegrals.You c an pr int reports of or displa y plots of lift, drag, and momen t coefficien ts, sur face in tegrations , and r esiduals f or the solution v ariables . For unst eady flo ws, you c an also monit or elapsed time . Creating r eport definitions f or monit oring is descr ibed in Creating R eport Definitions (p.2910 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2646Using the S olverFor additional inf ormation, see the f ollowing sec tions: 37.15.1. Monit oring R esiduals 37.15.2. Monit oring S tatistics 37.15.3. Monit oring S olution Q uantities 37.15.1. Monit oring Residuals At the end of each solv er it eration, the r esidual sum f or each of the c onser ved v ariables is c omput ed and st ored, ther eby recording the c onvergenc e hist ory.This hist ory is also sa ved in the da ta file .The residual sum is defined b elow. On a c omput er with infinit e pr ecision, these r esiduals will go t o zero as the solution c onverges. On an actual c omput er, the r esiduals dec ay to some small v alue (“ round-off ”) and then st op changing (“ level out”). For single-pr ecision c omputa tions (the default f or w orksta tions and most c omput ers), residuals can dr op as man y as six or ders of magnitude b efore hitting r ound-off . Double-pr ecision r esiduals c an drop up t o twelve or ders of magnitude . Guidelines f or judging c onvergenc e can b e found in Judging Convergenc e (p.2691 ). 37.15.1.1. Definition of R esiduals for the P ressur e-B ased S olver After discr etiza tion, the c onser vation equa tion f or a gener al variable at a c ell can b e wr itten as (37.6) Here is the c enter coefficien t, are the influenc e coefficien ts for the neighb oring c ells, and is the c ontribution of the c onstan t par t of the sour ce term in and of the b oundar y condi- tions . In Equa tion 37.6 (p.2647 ), (37.7) The r esidual comput ed b y ANSY S Fluen t’s pr essur e-based solv er is the imbalanc e in Equa- tion 37.6 (p.2647 ) summed o ver all the c omputa tional c ells .This is r eferred t o as the “unsc aled ” re- sidual. It ma y be wr itten as (37.8) In gener al, it is difficult t o judge c onvergenc e by examining the r esiduals defined b y Equa- tion 37.8 (p.2647 ) sinc e no sc aling is emplo yed.This is esp ecially tr ue in enclosed flo ws such as na tural convection in a r oom wher e ther e is no inlet flo w rate of with which t o compar e the r esidual. ANSY S Fluen t scales the r esidual using t wo kinds of sc aling fac tors, represen tative of the flo w rate of through the domain. The fac tors ar e termed global sc aling and local sc aling .The t ype of sc aling can b e selec ted fr om the Residual M onit ors dialo g box.The “globally sc aled ” residual is defined as (37.9) There ar e two instanc es wher e is mo dified in the denomina tor term : for momen tum equa tions , it is r eplac ed with the magnitude of the v elocity at cell ; and f or R eynold str ess equa tions , it is r e- 2647Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Monit oring S olution C onvergenc eplac ed with the tr ace of the R eynolds str ess t ensor a t cell divided b y the numb er of dimensions of the c ase (2D or 3D). The “locally sc aled ” residual is defined as (37.10) Note tha t for the momen tum and R eynolds str ess equa tions , and are mo dified in the same manner as f or global sc aling . The sc aled r esidual is a mor e appr opriate indic ator of c onvergenc e for most pr oblems .The selec tion of sc aling and c onvergenc e cr iteria for diff erent types of sc aling ar e discussed in Judging C onver- genc e (p.2691 ).The default r esiduals displa yed b y ANSY S Fluen t are global sc aling . For the c ontinuit y equa tion, the unsc aled r esidual f or the pr essur e-based solv er is defined as (37.11) The lo cal sc aling is the same f or all equa tions . However, the global sc aling tr eats continuit y in a dif- ferent way and it is defined as (37.12) The denomina tor is the lar gest absolut e value of the c ontinuit y residual in the first fiv e iterations . The sc aled r esiduals descr ibed ab ove ar e useful indic ators of solution c onvergenc e. Guidelines f or their use ar e giv en in Judging C onvergenc e (p.2691 ). It is sometimes useful t o det ermine ho w much a residual has decr eased dur ing c alcula tions as an additional measur e of c onvergenc e. For this pur pose, ANSY S Fluen t allo ws you t o nor maliz e the r esidual (either sc aled or unsc aled) b y dividing b y the maximum r esidual v alue af ter iterations , wher e is set b y you in the Residual M onit ors D ialog Box (p.3910 ) in the Iterations field under Residual Values . (37.13) Normaliza tion in this manner ensur es tha t the initial r esiduals f or all equa tions ar e of and is sometimes useful in judging o verall c onvergenc e. By default , .You c an also sp ecify the nor maliza tion fac tor (the denomina tor in Equa- tion 37.13 (p.2648 )) manually in the Residual M onit ors D ialog Box (p.3910 ). 37.15.1.2. Definition of R esiduals for the D ensit y-Based S olver A residual f or the densit y-based solv er is simply the time r ate of change of the c onser ved v ariable ( ).The RMS r esidual is the squar e root of the a verage of the squar es of the r esiduals in each c ell of the domain: (37.14) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2648Using the S olverEqua tion 37.14 (p.2648 ) is the unsc aled r esidual sum r eported f or all the c oupled equa tions solv ed b y ANSY S Fluen t’s densit y-based solv er. Imp ortant The r esiduals f or the equa tions tha t are solv ed sequen tially b y the densit y-based solv er (turbulenc e and other sc alars , as discussed in Densit y-Based S olver in the Theor y Guide ) are the same as those descr ibed ab ove for the pr essur e-based solv er. In gener al, it is difficult t o judge c onvergenc e by examining the r esiduals defined b y Equa- tion 37.14 (p.2648 ) sinc e no sc aling is emplo yed.This is esp ecially tr ue in enclosed flo ws such as na tural convection in a r oom wher e ther e is no inlet flo w rate of with which t o compar e the r esidual. As with the pr essur e-based solv er, ANSY S Fluen t uses t wo types of sc aling f or the densit y-based solv er. The globally sc aled r esidual is defined as (37.15) The denomina tor is the lar gest absolut e value of the r esidual in the first fiv e iterations . The lo cally sc aled r esidual is c alcula ted fr om the lo cal flux imbalanc e in the c ell. It is c alcula ted using Equa tion 37.16 (p.2649 ): (37.16) is the c onser vative variable and is the c ell v olume .The unsc aled r esidual is alw ays calcula ted from Equa tion 37.14 (p.2648 ). The sc aled r esiduals descr ibed ab ove ar e useful indic ators of solution c onvergenc e. Guidelines f or their use ar e giv en in Judging C onvergenc e (p.2691 ). It is sometimes useful t o det ermine ho w much a residual has decr eased dur ing c alcula tions as an additional measur e of c onvergenc e. For this pur pose, ANSY S Fluen t allo ws you t o nor maliz e the r esidual (either sc aled or unsc aled) b y dividing b y the maximum r esidual v alue af ter iterations , wher e is set b y you in the Residual M onit ors D ialog Box (p.3910 ) in the Iterations field under Residual Values . Normaliza tion of the r esidual sum is acc omplished b y dividing b y the maximum r esidual v alue af ter iterations , wher e is set b y you in the Residual M onit ors D ialog Box (p.3910 ) in the Iterations field under Residual Values : (37.17) Normaliza tion in this manner ensur es tha t the initial r esiduals f or all equa tions ar e of and is sometimes useful in judging o verall c onvergenc e. By default , , mak ing the nor maliz ed r esidual equiv alen t to the sc aled r esidual. You c an also specify the nor maliza tion fac tor (the denomina tor in Equa tion 37.17 (p.2649 )) manually in the Residual Monit ors D ialog Box (p.3910 ). 2649Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Monit oring S olution C onvergenc e37.15.1.3. Overview of Using the R esidual Monit ors D ialo g Box All inputs c ontrolling the monit oring of r esiduals ar e en tered using the Residual M onit ors D ialog Box (p.3910 )(Figur e 37.30: The R esidual M onit ors D ialog Box (p.2650 )). Solution → Monit ors → Residuals Edit... Figur e 37.30: The Residual M onit ors D ialo g Box In gener al, you will only need t o enable r esidual plotting and mo dify the c onvergenc e cr iteria using this dialo g box. Additional c ontrols ar e available f or disabling monit oring of par ticular r esiduals , and modifying nor maliza tion and plot par amet ers. 37.15.1.4. Printing and P lotting R esiduals By default , residual v alues f or all r elevant variables ar e pr inted in the c onsole af ter each it eration. If you w ant to disable this pr intout, turn off Print to Console under Options .To enable the plotting of residuals af ter each it eration, turn on Plot under Options . Residuals will b e plott ed in the gr aphics windo w (with the windo w ID set in the Windo w field) dur ing the c alcula tion. If you w ant to displa y a plot of the cur rent residual hist ory, simply click the Plot push butt on. 37.15.1.5. Storing R esidual Hist ory Points Residual hist ories f or each v ariable ar e aut oma tically sa ved in the da ta file , regar dless of whether the y are being monit ored.You c an c ontrol the numb er of hist ory points to be stored b y changing the It- erations t o Store entry. By default , up t o 1000 p oints will b e stored. If mor e than 1000 it erations ar e performed (tha t is, the limit is r eached), every other p oint will b e disc arded—lea ving 500 hist ory points—and the ne xt 500 p oints will b e stored.When the t otal hits 1000 again, every other p oint will again b e disc arded , and so on. If you ar e performing a lar ge numb er of it erations , you will lose a great deal of r esidual hist ory inf ormation a t the b eginning of the c alcula tion. In such c ases , you should increase the Iterations t o Store value t o a mor e appr opriate value . Of course , the lar ger this numb er Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2650Using the S olveris, the mor e memor y you will need , the longer the plotting will tak e, and the mor e disk spac e you will need t o store the da ta file . 37.15.1.6. Contr olling N ormalization and Sc aling By default , scaling of r esiduals (see Equa tion 37.9 (p.2647 ) and Equa tion 37.15 (p.2649 )) is enabled and the default c onvergenc e cr iterion is for ener gy and P-1 equa tions and for all other equa tions . When the Scale option is enabled , global sc aling will b e applied b y default. You c an then enable the Comput e Local Sc ale option and selec t the Rep orting Option from the dr op-do wn list. You ha ve a choic e to plot or pr int to the c onsole the local sc aling or the global sc aling of r esiduals . By default , the global sc aling of r esiduals will b e plott ed. Note When Comput e Local Sc ale is enabled , ANSY S Fluen t comput es and st ores b oth the locally and globally sc aled r esiduals fr om subsequen t iterations , for the pur pose of reporting .The sc aled r esiduals ar e stored in the da ta file . Imp ortant Onc e the Comput e Local Sc ale option is enabled and y ou disable the Scale option, the Comput e Local Sc ale option will not aut oma tically b e disabled . Inst ead, it will comput e both the lo cally and globally sc aled r esiduals , but only pr int or plot the un- scaled r esidual. Residual nor maliza tion (tha t is, dividing the r esiduals b y the lar gest v alue dur ing the first f ew it erations) is also a vailable but disabled b y default. Normaliza tion c an b e used with b oth sc aled and unsc aled r esiduals . Note tha t if nor maliza tion is en- abled , the c onvergenc e cr iterion ma y need t o be adjust ed appr opriately. See Judging C onver- genc e (p.2691 ) for inf ormation ab out judging c onvergenc e based on the diff erent types of r esidual reports. (Both the r aw residuals and sc aling fac tors ar e stored in the da ta file , so y ou c an swit ch between sc aled and unsc aled r esiduals .) To report unsc aled r esiduals , simply disable the Scale option under Residual Values . Imp ortant If you swit ch fr om sc aled t o unsc aled r esiduals (or vic e versa) and y ou ar e nor malizing the residuals (as descr ibed b elow), you must click the Renor maliz e butt on t o recomput e the normaliza tion fac tors. If you w ant to nor maliz e the r esiduals (see Equa tion 37.13 (p.2648 ) or Equa tion 37.17 (p.2649 )), enable the Normaliz e option under Residual Values .The Normaliza tion F actor column will b e added t o the dialo g box at this time . ANSY S Fluen t will nor maliz e the pr inted or plott ed r esidual f or each v ariable by the v alue indic ated as the Normaliza tion F actor for tha t variable .The default Normaliza tion Factor is the maximum r esidual v alue af ter the first 5 it erations .To use the maximum r esidual v alue after a diff erent numb er of it erations (tha t is, specify a diff erent value f or in Equa tion 37.13 (p.2648 ) or Equa tion 37.17 (p.2649 )), you c an mo dify the Iterations entry under Residual Values . 2651Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Monit oring S olution C onvergenc eIn some c ases , the maximum r esidual ma y occur sometime af ter the it eration sp ecified in the Iterations field . If this should o ccur , you c an click the Renor maliz e butt on t o set the nor maliza tion fac tors f or all v ariables t o the maximum v alues in the r esidual hist ories. Subsequen t plots and pr inted r eports will use the new nor maliza tion fac tor. You c an also sp ecify the nor maliza tion fac tor (the denomina tor in Equa tion 37.13 (p.2648 ) or Equa- tion 37.17 (p.2649 )) explicitly .To mo dify the nor maliza tion fac tor for a par ticular v ariable , enter a new value in the c orresponding Normaliza tion F actor field in the Residual M onit ors D ialog Box (p.3910 ). If you w ant to report unnor maliz ed, unsc aled r esiduals ( Equa tion 37.8 (p.2647 ) or Equa tion 37.14 (p.2648 )), disable the Normaliz e and Scale options under Residual Values in the Residual M onit ors D ialog Box (p.3910 ). Note tha t unnor maliz ed, unsc aled r esiduals ar e stored in the da ta file r egar dless of whether the r eported r esiduals ar e nor maliz ed or sc aled . 37.15.1.7. Choosing a C onvergenc e Criterion The abilit y to cho ose c ertain c onvergenc e cr iteria pr ovides y ou with alt ernative ways to check c onver- genc e when using the it erative transien t solv er.The v arious c onvergenc e cr iteria can b e selec ted in the Residual M onit ors dialo g box from the Convergenc e Criterion drop-do wn list. Solution → Monit ors → Residuals Edit... Figur e 37.31: The Residual M onit ors D ialo g Box Displa ying Rela tive or A bsolut e Convergenc e Four options ar e available f or check ing an equa tion f or c onvergenc e: absolut e This is the default. For st eady-sta te cases ,absolut e and none are the only options a vailable f or selec tion. The r esidual (sc aled and/or nor maliz ed) of an equa tion a t an it eration is c ompar ed with a user-sp ecified Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2652Using the S olvervalue . If the r esidual is less than the user-sp ecified v alue , tha t equa tion is deemed t o ha ve converged for a time st ep. relative The r esidual of an equa tion a t an it eration of a time st ep is c ompar ed with the r esidual a t the star t of the time st ep. If the r atio of the t wo residuals is less than a user-sp ecified v alue , tha t equa tion is deemed to ha ve converged f or a time st ep. relative or absolut e If either the absolut e convergenc e criterion or the relative convergenc e criterion is met , the equa tion is consider ed c onverged . The Rela tive Criteria can b e set when relative or relative or absolut e is selec ted. none Convergenc e check ing is disabled . In man y situa tions , the absolut e convergenc e cr iterion c ould b e too str ingen t for tr ansien t flo ws causing a lar ge numb er of it erations p er time st ep. For e xample , the sc aling of the c ontinuit y equa tion is based on the v alue of the c ontinuit y residual in the first fiv e iterations .The sc aling fac tor c ould b e low if the initial c ontinuit y residual is small and ther efore the sc aled r esidual c ould fail t o meet the absolut e convergenc e cr iterion. With the relative convergenc e cr iterion, convergenc e is check ed b y compar ing the r esidual a t an it eration of a time st ep with the r esidual a t the b eginning of the time step and henc e this pr oblem is alle viated.The relative or absolut e convergenc e cr iterion is useful in situa tions wher e the r esiduals of some of the equa tions ar e alr eady very low at the star t of a time step (f or e xample , when a par ticular v ariable has r eached st eady-sta te), and the or der of magnitude reduc tion in r esiduals is not p ossible .The none option allo ws you t o disable c onvergenc e check ing by selec ting the option in the Convergenc e Criterion drop-do wn list. Imp ortant relative and relative or absolut e convergenc e cr iteria ar e available only with the unst eady pressur e-based solv er and unst eady densit y-based solv er. The t ext command used t o acc ess the c onvergenc e cr iterion is solve → monitors → residual → criterion-type When criterion-type is en tered, you will ha ve the f ollowing choic es: Type Criterion absolut e 0 relative 1 relative or absolut e 2 none 3 2653Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Monit oring S olution C onvergenc eFor criterion-type 1 or 2, the t ext command relative-conv-criteria will app ear under the residual text menu , wher e the v arious relative-conv-criteria can b e set. Imp ortant If the NIT A solv er is enabled , no c onvergenc e cr iteria ar e available f or selec tion. 37.15.1.8. Mo difying C onvergenc e Criteria Depending on the Convergenc e Criterion you cho ose, ANSY S Fluen t will check f or c onvergenc e. If convergenc e is b eing monit ored, the solution will st op aut oma tically when each v ariable meets its specified c onvergenc e cr iterion. Convergenc e checks c an only b e performed on v ariables whose r e- siduals ar e being monit ored (v ariables with the Monit or option enabled). You c an cho ose whether or not y ou w ant to check the c onvergenc e for each v ariable b y enabling or disabling the Check C onvergenc e option f or it in the Residual M onit ors D ialog Box (p.3910 ).To modify the c onvergenc e cr iterion f or a par ticular v ariable , enter a new v alue in the c orresponding convergenc e cr iterion field . 37.15.1.9. Disabling Monit oring If your pr oblem r equir es the solution of man y equa tions (f or e xample , turbulenc e quan tities and multiple sp ecies), a plot tha t includes all r esiduals ma y be difficult t o read. In such c ases , you ma y choose t o monit or only a subset of the r esiduals , perhaps those tha t aff ect convergenc e the most. You c an indic ate whether or not y ou w ant to monit or residuals f or each v ariable b y enabling or dis- abling the r elevant check b ox in the Monit or list of the Residual M onit ors D ialog Box (p.3910 ). 37.15.1.10. Plot P aramet ers If you cho ose t o plot the r esidual v alues (either in teractively dur ing the solution or using the Plot butt on af ter calcula tions ar e complet e), ther e ar e se veral displa y par amet ers y ou c an mo dify. In the Windo w field under Options , you c an sp ecify the ID of the gr aphics windo w in which the plot will b e dr awn. When ANSY S Fluen t is it erating , the ac tive gr aphics windo w is t emp orarily set t o this windo w to up date the r esidual plot , and then r etur ned t o its pr evious v alue .Thus, the r esidual plot can b e main tained in a separ ate windo w tha t do es not in terfere with other gr aphic al p ostpr ocessing . You c an mo dify the numb er of r esidual hist ory points to be displa yed in the plot b y changing the Iterations t o Plot entry under Options . If you sp ecify points, ANSY S Fluen t will displa y the last history points. Since the axis is sc aled b y the minimum and maximum v alues of all p oints in the plot , you c an z oom in on the end of the r esidual hist ory by setting Iterations t o Plot to a v alue smaller than the numb er of it erations p erformed . If, for e xample , the r esiduals jump ed ear ly in the calcula tion when y ou tur ned on turbulenc e, tha t peak br oadens the o verall range in r esidual v alues , mak ing the smaller fluc tuations la ter on almost indistinguishable . By setting the v alue of Iterations to Plot so tha t the plot do es not include tha t ear ly peak, your -axis r ange is b etter suit ed t o the values tha t you ar e in terested in seeing . For mor e inf ormation on r esidual hist ory points, refer to the discussion of st oring r esidual hist ory points, descr ibed ear lier in this sec tion. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2654Using the S olverYou c an also mo dify the a ttribut es of the plot ax es and the r esidual cur ves. Click the Axes... or Curves... butt on t o op en the Axes D ialog Box (p.3717 ) or Curves D ialog Box (p.3720 ). See Axes D ialog Box (p.3717 ) and Curves D ialog Box (p.3720 ) for details . Imp ortant Note tha t en tering a v alue f or Iterations t o Plot does not nec essar ily mean solved iterations but r ather stored (or sampled) da ta p oints. Note also tha t the fr equenc y of the da ta st orage will diminish t owards the star t of the solution as the numb er of solv ed it erations incr eases . Due t o this , whene ver the stored iterations is gr eater than the solved iterations , if y ou plot n iterations , you ac tually see a hist ory tha t go es back fur ther than n solv ed it erations . 37.15.1.11. Postpr ocessing R esidual Values If you ar e ha ving solution c onvergenc e difficulties , it is of ten useful t o plot the r esidual v alue fields (for e xample , using c ontour plots) t o det ermine wher e the high r esidual v alues ar e lo cated.When you use the densit y-based solv er, the r esidual v alues f or all solution v ariables ar e available in the Residuals ... categor y in the p ostpr ocessing dialo g boxes. (If you r ead c ase and da ta files in to ANSY S Fluen t, you will need t o perform a t least one it eration b efore the r esidual v alues ar e available f or postpr ocessing .) For the pr essur e-based solv er, however, only the mass imbalanc e in each c ell is available b y default. Imp ortant The r esidual v alues tha t are made a vailable f or p ostpr ocessing ar e the unsc aled v alues . If you w ant to plot r esidual v alue fields f or a pr essur e-based solv er calcula tion, you will need t o do the f ollowing: 1.Read in the c ase and da ta files of in terest (if the y are not alr eady in the cur rent session). 2.Use the expert command in the solve/set/ text menu t o enable the sa ving of r esidual v alues . solve → set → expert Among other questions , ANSY S Fluen t will ask if y ou w ant to sa ve cell r esiduals f or p ostpr ocessing . Enter yes or y, and k eep the default settings f or all of the other questions (b y pr essing the key). 3.Perform at least one it eration. The solution v ariables f or which r esidual v alues ar e available will app ear in the Residuals ... categor y in the p ostpr ocessing dialo g boxes. Note tha t residual v alues ar e not available f or the r adia tive transp ort equa tions solv ed b y the discr ete or dina tes radia tion mo del. 37.15.2. Monit oring S tatistics If you ar e solving a fully-de velop ed p eriodic flo w, you ma y want to monit or the pr essur e gr adien t or the bulk t emp erature ratio, as discussed in Periodic F lows (p.1206 ). If you ar e solving an unst eady flo w (esp ecially if y ou ar e using the e xplicit time st epping option), you may want to monit or the “time ” tha t has elapsed dur ing the c alcula tion. The ph ysical time of the flo w 2655Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Monit oring S olution C onvergenc efield star ts at zero when y ou initializ e the flo w. (See Performing Time-D ependen t Calcula tions (p.2626 ) for details ab out mo deling unst eady flo ws.) If you ar e using an adaptiv e time st epping metho d (descr ibed in User Inputs f or Time-D ependen t Problems (p.2627 )), you ma y want to monit or the siz e of the time st ep, . You c an cr eate report files and plots f or each of these quan tities: flow-time , delta-time , iterations-p er- timest ep, periodic-pr essur e-gr adien t, and p eriodic-bulk-t emp erature-ratio. All can b e included in a single r eport file; flow-time and delta-time c an b e included in the same r eport plot , as c an p eriodic- pressur e-gr adien t and p eriodic-bulk-t emp erature-ratio. For inf ormation on setting up r eport files and plots , see Report Files and R eport Plots (p.2929 ). Solution → Monit ors → Rep ort File New... Figur e 37.32: Rep ort File f or 'flo w-time', 'delta-time', and 'it ers-p er-timest ep' 37.15.3. Monit oring S olution Q uan tities Solution quan tities f or which R eport Definitions ha ve been cr eated c an b e monit ored thr oughout the solution t o aid in judging c onvergenc e.You c an setup y our c ase file so tha t force and momen t coeffi- cien ts and sur face and v olume in tegrals ar e comput ed and st ored a t the end of e very iteration (f or steady-sta te solutions) or time st ep (f or tr ansien t solutions), and ther eby create a c onvergenc e hist ory. You c an also cho ose t o comput e the v alue a veraged o ver se veral it erations/time st eps. Running a verages can also help y ou det ermine if y ou ha ve reached c onvergenc e for a solution tha t is oscilla ting or ir reg- ular.You c an pr int and plot and sa ve this c onvergenc e da ta to an e xternal file using R eport Files and Report Plots.The e xternal file is wr itten in the r eport file f ormat descr ibed in Report Files and R eport Plots (p.2929 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2656Using the S olverReport Files and R eport Plots ar e acc essible under the Monit ors node in the tr ee. Solution → Monit ors → Rep ort Files or Rep ort Plots For additional inf ormation on setting up r eport definitions and r eport files and plots , see Monit oring and R eporting S olution D ata (p.2910 ) and Creating R eport Definitions (p.2910 ). 37.16. Convergenc e Conditions The c onvergenc e conditions facilit y allo ws you t o set c onvergenc e conditions on the solution tha t are based on the v alues fr om r eport definitions (sur face, volume , lift, drag, and so on). There ar e two choic es that you must mak e for declar ing c onvergenc e using r eport definitions: •Do you w ant to check f or convergenc e at every iteration or a t every timest ep? M ake your choic e in the Check F or group b ox. –Solution C onvergenc e Fluen t checks f or solution c onvergenc e at every time st ep. –Time S tep C onvergenc e Fluen t checks f or solution c onvergenc e at every iteration. •Do you c onsider the solution c onverged if all of the ac tive report definitions' cr iteria and enabled r esiduals are sa tisfied or any of the ac tive report definitions' cr iteria or enabled r esiduals is sa tisfied? M ake your choic e in the Choose C ondition group b ox. –All Conditions ar e M et The solution is c onsider ed c onverged when all of the ac tive report definitions' cr iteria and enabled residuals ar e sa tisfied . –Any Condition is M et The solution is c onsider ed c onverged when an y of the ac tive report definitions cr iteria and enabled residuals is sa tisfied . By default , the solution c onvergenc e will happ en if either r eport definition c onvergenc e cr iteria or r e- siduals c onvergenc e cr iteria is sa tisfied . If you w ant to rely only on the r eport definition v alues t o decide convergenc e, clear the Check C onvergenc e check b oxes in the Residual M onit ors dialo g box. To op en the Convergenc e Conditions dialo g box, click the Convergenc e... butt on in the Solution ribbon tab ( Rep orts group b ox). Solution → Rep orts → Convergenc e... 2657Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Convergenc e ConditionsThe Active column of check b oxes (on the lef t) allo ws you t o deac tivate/ac tivate convergenc e conditions . 37.16.1. Setting U p the C onvergenc e Conditions D ialo g Box Create new c onvergenc e conditions b y click ing Add and selec ting a Rep ort Definition from the dr op- down list. To cr eate meaning ful c onditions f or det ermining c onvergenc e from r eport definitions , set the le vels of the c onvergenc e condition v ariables acc ording t o the f ollowing dir ections . Enter a v alue in the Ignor e Iterations B efore | Ignor e Time S teps B efore column if y ou e xpect your solution t o fluc tuate in the first f ew it erations/time st eps. Enter a v alue tha t represen ts the numb er of iterations/time st eps y ou an ticipa te the fluc tuations t o continue .The c alcula tion will b egin af ter this numb er of it erations/time st eps has finished . Use the Use I terations | U se Time S teps setting t o selec t the numb er of pr evious it erations/time st eps to be included in the monit or c onvergenc e check. For fluc tuating simula tions lik e Figur e 37.33: Fluctu- ating S imula tion Example (p.2659 ), this numb er should b e high enough t o coun teract the eff ect of the fluctuations . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2658Using the S olverFigur e 37.33: Fluctuating S imula tion E xample The Stop C riterion indic ates the cr iterion b elow which the solution is c onsider ed t o be converged . The v alue of Stop C riterion is c alcula ted as f ollows: Res-m(1) = [abs (m(n) - m(n-1))]/m(n) Res-m(2) = [abs (m(n) - m(n-2))]/m(n) Res-m(3) = [abs (m(n) - m(n-3))]/m(n) . . . Res-m(Np) = [abs (m(n) - m(n-Np))]/m(n) Where: Res-m is the r eport definition r esidual n is the it eration/time st ep numb er m(n) is the v alue of the r eport definition a t the nth iteration/time st ep Np is the numb er of pr evious it erations/time st eps t o consider ( Use I terations /Use Time S teps) The r eport definition r esidual is the absolut e varianc e of the monit ored quan tity over the last Np it er- ations/time st eps, divided b y the cur rent value of the monit ored quan tity. If the maximum v alue of all of the R es-m v alues is less than the Stop C riterion numb er, the solution is consider ed t o be converged a t the nth iteration/time st ep. If the maximum v alue of all of the R es-m 2659Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Convergenc e Conditionsvalues is gr eater than or equal t o the Stop C riterion numb er, the c alcula tion will pr oceed t o the ne xt iteration/time st ep. Selec t the Print check b ox to pr int report definition r esiduals in the ANSY S Fluen t console .These r e- siduals ar e calcula ted as f ollows with r espect to their immedia te pr evious v alue only . Pres-m(n) = [abs (m(n) - m(n-1))]/m(n) Where: Pres- m(n) is the pr inted r esidual v alue f or a r eport definition n is the it eration tha t is cur rently pr inted in the c onsole m(n) is the v alue of the monit or a t the nth iteration/time st ep Therefore: Pres-m(n +1) = [abs (m(n+1) - m(n))]/m(n+1) The pr inted v alue a t the (n+1)th it eration/time st ep is c alcula ted with r espect to the (n)th it eration/time step and the pr inted v alue a t the (n)th it eration/time st ep is c alcula ted with r espect to the (n-1)th it er- ation/time st ep. 37.17. Executing C ommands D uring the C alcula tion As descr ibed in Monit oring S olution C onvergenc e (p.2646 ) and Anima ting the S olution (p.2670 ), respectively, you c an r eport and monit or v arious quan tities (f or e xample , residuals , force coefficien ts) and cr eate anima tions of the solution while the solv er is p erforming c alcula tions . ANSY S Fluen t also includes a feature tha t allo ws you t o define y our o wn c ommand(s) t o be execut ed dur ing the c alcula tion a t sp ecified intervals. For e xample , you c an ask ANSY S Fluen t to adapt the mesh based on gr adien t field v alue c ell regist ers af ter a set numb er of it erations .You will sp ecify a ser ies of t ext commands or use the GUI t o define the st eps t o be performed . Imp ortant Note tha t the Calcula tion A ctivities task page pr ovides options t o perform the f ollowing during the c alcula tion: •save case and da ta files •export transien t solution files •export transien t par ticle hist ory da ta files Each of these options has their o wn dialo g box, which should b e used r ather than e xecuting a command t o perform them. See Automa tic S aving of C ase and D ata Files (p.591) and Ex- porting D ata D uring a Transien t Calcula tion (p.627) for details . You will indic ate the c ommand(s) tha t you w ant the solv er to execut e at sp ecified in tervals dur ing the calcula tion using the Execut e Commands D ialog Box (p.3637 ) (Figur e 37.34: The Ex ecut e Commands Dialog Box (p.2661 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2660Using the S olverSolution → Calcula tion A ctivities → Execut e Commands New... Figur e 37.34: The E xecut e Commands D ialo g Box The pr ocedur e is as f ollows: 1.Increase the Defined C ommands value t o the numb er of c ommands y ou w ant to sp ecify . As this v alue is increased , additional c ommand en tries will b ecome editable . For each c ommand , you will p erform the following st eps. 2.Enable the Active check butt on ne xt to the c ommand if y ou w ant it t o be execut ed dur ing the c alcula tion. You ma y define multiple c ommands and cho ose t o use only a subset of them b y tur ning off the check butt on f or those tha t you do not w ant to use . 3.Enter a name f or the c ommand under the Name heading . 4.Indic ate ho w of ten y ou w ant the c ommand t o be execut ed b y setting the in terval under Every and selec ting Iteration Time S tep or Flow Time in the dr op-do wn list b elow When . (Time S tep and Flow Time are only valid choic es if y ou ar e calcula ting unst eady flo w.) For e xample , to execut e the c ommand e very 10 it erations , you w ould en ter 10 under Every and selec t Iteration under When . Imp ortant If you sp ecify an in terval in it erations , be sur e to keep the Rep orting In terval in the Run Calcula tion Task P age (p.3640 ) at its default v alue of 1. 2661Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Executing C ommands D uring the C alcula tion5.Define the c ommand b y en tering a ser ies of t ext commands in the Command field , or b y en tering the name of a c ommand macr o you ha ve defined (or will define) as descr ibed in Defining M acros (p.2662 ). Note Make sur e tha t the t ext commands y ou ha ve en tered in the Command field of the Execut e Commands dialo g box do es not e xceed 127 char acters. Imp ortant •If the c ommand t o be execut ed in volves sa ving a file , see Saving F iles D uring the C alcula- tion (p.2664 ) for imp ortant inf ormation. •If the c ommand enables or disables equa tions , you must disable the c onvergenc e check f or these equa tions . For additional inf ormation, see the f ollowing sec tions: 37.17.1. Defining M acros 37.17.2. Saving F iles D uring the C alcula tion 37.17.1. Defining M acros You c an also use the macr os tha t you define f or aut oma tic e xecution dur ing the c alcula tion, interactively during the pr oblem setup or p ostpr ocessing . For e xample , if y ou define a macr o tha t adapts the mesh after each it eration, you c an also use the macr o to perform this adaption in teractively. Definition of a macr o is acc omplished as f ollows: 1.In the Execut e Commands D ialog Box (p.3637 ), click the Define M acro... butt on t o op en the Define M acro Dialog Box (p.3638 ) (Figur e 37.35: The D efine M acro Dialog Box (p.2663 )). Since this is a “modal” dialo g box, the solv er will not allo w you t o do an ything else un til you p erform st ep 2, below. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2662Using the S olverFigur e 37.35: The D efine M acro D ialo g Box 2.In the Define M acro dialo g box, specify a Name for the macr o (for e xample ,adapt1 ) and click OK. (The Define M acro... butt on in the Execut e Commands dialo g box will b ecome the End M acro butt on.) 3.Perform the st eps tha t you w ant the macr o to perform. For e xample , if you w ant the macr o to perform adaption, open the Adaption C ontrols dialo g box, specify the appr opriate coarsening , refinemen t, and other par amet ers, and click Adapt to perform the adaption. Imp ortant If the c ommand t o be execut ed in volves sa ving a file , see Saving F iles D uring the C alcu- lation (p.2664 ) for imp ortant inf ormation. 4.When y ou ha ve complet ed the st eps y ou w ant the macr o to perform, click the End M acro butt on in the Execut e Commands dialo g box. As not ed ab ove, onc e you ha ve defined a macr o for e xecution dur ing the c alcula tion, you c an use it at an y time . If you defined the macr o called adapt1 to adapt based on pr essur e gr adien t, you c an simply t ype adapt1 in the c onsole t o perform this adaption. This macr o is indep enden t of an y text menus , so y ou need not mo ve to a diff erent text menu t o use it. Macros c an b e sa ved t o and r ead from files .To sa ve all macr os tha t are cur rently defined , use the file/write-macros text command . To read all the macr os in a macr o file , use the file/read-macros text command . Imp ortant A macr o, like a jour nal file , is a simple r ecord/pla yback func tion. It will ther efore know nothing ab out the sta te in which it w as recorded or the sta te in which it is b eing pla yed back. You must b e careful not t o change dir ectories while defining a macr o. Also, you must 2663Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Executing C ommands D uring the C alcula tionbe careful tha t all sur faces, variables , and so on tha t are used b y the macr o ha ve been properly defined when y ou (or ANSY S Fluen t) in voke the macr o. 37.17.2. Saving F iles D uring the C alcula tion If the c ommand t o be execut ed dur ing the c alcula tion in volves sa ving a file , you should include a special char acter in the file name when y ou en ter it in The S elec t File D ialog Box (p.569) so tha t the solv er will k now to assign a new name t o each file it sa ves. See Automa tic N umb ering of F iles (p.585) for details ab out these sp ecial char acters f or filenames . Imp ortant Note tha t the Calcula tion A ctivities task page pr ovides options t o perform the f ollowing during the c alcula tion: •save case and da ta files •export transien t solution files •export transien t par ticle hist ory da ta files Each of these options has their o wn dialo g box, which should b e used r ather than the Ex- ecut e Commands dialo g box. See Automa tic S aving of C ase and D ata Files (p.591) and Ex- porting D ata D uring a Transien t Calcula tion (p.627) for details . 37.18. Automa tic Initializa tion of the S olution and C ase M odific ation While r unning a c ase manually , you c an p erform certain ac tivities tha t ma y facilita te convergenc e.These actions ma y tak e plac e before initializa tion, after initializa tion and/or a t other p oints dur ing the c alcula- tion. The pr ocess descr ibed in this sec tion allo ws you t o en ter text commands a t each of these times when a c ase is r un fr om the Run C alcula tion task page ,Workbench, or in ba tch. In the Calcula tion Activities task page , enable Automa tically Initializ e Solution and M odify C ase to aut oma tically modify the c ase. Solution → Calcula tion A ctivities → Automa tically Initializ e Solution and M odify C ase → Edit... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2664Using the S olverFigur e 37.36: The A utoma tically Initializ e Solution and M odify C ase Option When using this option, you c an edit the c alcula tion settings . Note tha t the or iginal settings alw ays exist and c annot b e delet ed.The dur ation of the c alcula tion is defined , so immedia tely af ter enabling Automa tically Initializ e Solution and M odify C ase, you will notic e tha t the Calcula tion A ctivities task page r eports tha t the c ase will b e run with the or iginal settings f or a single it eration. 2665Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Automa tic Initializa tion of the S olution and C ase M odific ationYou c an no w control the numb er of it erations or time st eps f or the c alcula tion. When Automa tically Initializ e Solution and M odify C ase option is disabled , you will ha ve to sp ecify the it erations or time steps using the Run C alcula tion task page . For an uninitializ ed c ase, click ing the Edit... butt on will displa y the Automa tic S olution Initializa tion and C ase M odific ation dialo g box, which allo ws you t o sp ecify the initializa tion metho d and t o mo dify the c ase. Figur e 37.37: The A utoma tic S olution Initializa tion and C ase M odific ation D ialo g Box In the Initializa tion M etho d tab , you c an sp ecify f our diff erent initializa tion metho ds: Initializ e with Values fr om the C ase uses the v alues set in the Solution Initializa tion task page . Note Hybrid initializa tion is not p erformed f or this option; even if y ou ha ve selec ted Hybr id Initializa tion under the Solution Initializa tion task page . Use S olution D ata fr om F ile requir es y ou t o read in a da ta file c ontaining the desir ed initializa tion f or this c ase, as sho wn in Fig- ure 37.37: The A utoma tic S olution Initializa tion and C ase M odific ation D ialog Box (p.2666 ). Use E xisting S olution D ata is analo gous t o changing the v alues in a c ase and c ontinuing the c alcula tion. However, the it eration c oun ter will b e reset t o 0 so tha t the mo dific ations c an b e applied . Use this metho d when no solution da ta exists , similar t o the first r un. Imp ortant Whene ver the c ase is initializ ed, the it eration c oun t is set t o 0. In the Case M odific ation tab , you c an indic ate ho w long y ou w ould lik e to run with the or iginal settings , then mak e an y mo dific ations t o the c ase settings . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2666Using the S olverFigur e 37.38: The C ase M odific ation Tab If you decide t o mak e no mo dific ations , then the c oun ter in the Defined M odific ations box will b e set to 0. However, you still ha ve the option t o sp ecify settings tha t you w ould lik e to apply b efore initializ- ation, or y ou c an change y our or iginal settings . If Before Initializa tion is enabled , then y ou c an t ype the t ext commands in the Commands field . If Original S ettings is enabled , you c an t ype text commands in the Commands field , and/or sp ecify the Numb er of I terations/T ime S teps.When en tering mor e than one t ext command in a single Commands field , begin each t ext command with a /, as sho wn in Figur e 37.38: The C ase M odific ation Tab (p.2667 ). Note Make sur e tha t the t ext commands y ou ha ve en tered in the Commands field do es not exceed 127 char acters. Imp ortant Note tha t some t ext commands r equir e ar gumen ts (f or e xample , numb ers, file names , yes/no responses), which ar e request ed thr ough f ollow-up pr ompts in the c onsole .When en tering such t ext commands in the Commands field of the Case M odific ation tab , be sur e to include your r esponses t o the pr ompts . If you do not include these r esponses , the asso ciated c om- mand will not b e execut ed (unless it is a y es/no question, in which c ase ANSY S Fluen t will use yes by default). If you decide t o run the c alcula tion fur ther with mo dific ations t o your c ase, incr ease the numb er of Defined M odific ations and sp ecify additional c ommands .The settings sho wn in Figur e 37.38: The C ase Modific ation Tab (p.2667 ) result in the f ollowing ac tions: 1.The default initial v alues f or initializa tion ar e comput ed fr om the v elocity-inlet z one Velocity-inlet-5 . 2.The it eration c oun t is set t o 0 (in all situa tions) and the solution is initializ ed. 3.The c alcula tion is r un f or 100 it erations or un til convergenc e. 4.The C ourant numb er is set t o 3.5. 5.The c alcula tion c ontinues f or 75 it erations or un til convergenc e. 2667Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Automa tic Initializa tion of the S olution and C ase M odific ation6.The discr etiza tion scheme f or turbulen t kinetic ener gy is set t o sec ond or der up wind , and the C ourant numb er is set t o 2.5. 7.The c alcula tion c ontinues f or 1000 it erations or un til convergenc e. You c an mak e the ab ove changes sequen tially and r un y our c ase, or y ou c an sp ecify them all a t onc e. When y ou ha ve complet ed mak ing the mo dific ations , click OK. A Question dialo g box ma y app ear, prompting y ou t o tak e sp ecific ac tions . For e xample , if the Original S ettings field is empt y, then y ou may be notified tha t the or iginal settings will b e lost if the c ase is sa ved af ter the mo dific ations ar e applied . It will pr ompt y ou f or a r esponse when ask ed if y ou w ould lik e to add c ommands tha t sp ecify the or iginal settings . Imp ortant If you sp ecify c ommands f or the Original S ettings , the y will b e applied t o the c ase b efore the first it eration/time st ep. Your ac tions will b e summar ized in the Calcula tion A ctivities task page , as sho wn in Figur e 37.36: The Automa tically Initializ e Solution and M odify C ase Option (p.2665 ). If you disable Automa tically Initializ e Solution and M odify C ase, the settings will b e disabled and retained , but will not b e applied t o the c ase. When Automa tically Initializ e the S olution and M odify the C ase is enabled , settings defined in the Run C alcula tion task page will b e ignor ed. Inst ead, the Numb er of I terations will b e defined as Automa tic, as sho wn in Figur e 37.39: The R un C alcula tion Task P age (p.2669 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2668Using the S olverFigur e 37.39: The R un C alcula tion Task P age For additional inf ormation, see the f ollowing sec tions: 37.18.1. Altering the S olution Initializa tion and C ase M odific ation af ter C alcula ting 37.18.1. Altering the S olution Initializa tion and C ase M odific ation af ter C al- cula ting If you decide t o edit the solution initializa tion and c ase mo dific ation settings and one or mor e iterations have been c alcula ted, then click ing the Edit... butt on f or the Automa tically Initializ e Solution and Modify C ase option will op en the Edit A utoma tic Initializa tion and C ase M odific ations dialo g box, as sho wn in Figur e 37.40: The E dit A utoma tic Initializa tion and C ase M odific ations D ialog Box (p.2670 ). 2669Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Automa tic Initializa tion of the S olution and C ase M odific ationFigur e 37.40: The E dit A utoma tic Initializa tion and C ase M odific ations D ialo g Box If you selec t the first option, the initializa tion c ontrols and mo dific ations tha t ha ve alr eady tak en plac e are disabled , ther efore you c an edit the c ase mo dific ations tha t ha ve yet to tak e plac e. If you selec t the sec ond option, all c ontrols in the Automa tic S olution Initializa tion and C ase Modific ation dialo g box are enabled and ther efore, you c an mo dify an y of the settings . 37.19. Anima ting the S olution During the c alcula tion, you c an ha ve Fluen t create an anima tion of mesh (pr imar ily for d ynamic mesh cases), contours , vectors, pathlines , par ticle tr acks , scenes , XY plots , report plots , or r esiduals . Before you b egin the c alcula tion, you will sp ecify and displa y the v ariables and t ypes of plots y ou w ant to anima te, and ho w of ten y ou w ant plots t o be sa ved. At the sp ecified in tervals, Fluen t will displa y the request ed plots , and st ore each one .When the c alcula tion is c omplet e, you c an pla y back the anima tion sequenc e, mo dify the view (f or mesh, contour, vector, pathline , and par ticle tr acks plots), if desir ed, and save the anima tion t o a ser ies of pic ture files or an MPEG file . Instr uctions f or defining a solution anima tion sequenc e ar e pr ovided in Creating an A nima tion D efini- tion (p.2670 ).Playing an A nima tion S equenc e (p.2673 ) descr ibes ho w to pla y back and sa ve the anima tions . For additional inf ormation, see the f ollowing sec tions: 37.19.1. Creating an A nima tion D efinition 37.19.2. Playing an A nima tion S equenc e 37.19.3. Saving an A nima tion S equenc e 37.19.4. Reading an A nima tion S equenc e 37.19.1. Creating an A nima tion D efinition You c an use Figur e 37.41: The A nima tion D efinition D ialog Box (p.2671 ) to sp ecify the anima tion objec t and the fr equenc y tha t it will b e captur ed f or anima ting . Solution → Activities → Create → Solution A nima tions ... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2670Using the S olverFigur e 37.41: The A nima tion D efinition D ialo g Box The pr ocedur e is as f ollows: 1.(Optional) En ter a Name for the anima tion definition. 2.Indic ate ho w of ten y ou w ant to create a new fr ame in the anima tion b y sp ecifying a fr equenc y in Rec ord after e very and selec ting Iteration ,Time S tep, or Flow Time . 3.Specify ho w you w ant Fluen t to sa ve the anima tion fr ames b y selec ting In M emor y,PPM Image (2D image file), or HSF F ile (3D image file) fr om the Storage Type drop-do wn. Imp ortant The ad vantage t o sa ving the anima tion sequenc e using the HSF F ile option is tha t these files ar e highly c ompr essible and c an b e view ed and in teracted with using a “HOOPS Viewer” applic ation on iOS and A ndroid equipp ed de vices.The “HOOPS Viewer” applic- ation c an b e do wnloaded t o iOS and A ndroid equipp ed de vices fr om the “App S tore” and “Google P lay” respectively. 2671Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Anima ting the S olutionAn ad vantage t o sa ving the anima tion sequenc e using the PPM Image option is tha t you c an use the separ ate pixmap image files f or the cr eation of a single GIF file . GIF file creation c an b e done quick ly with gr aphics t ools pr ovided b y other thir d-par ty gr aphics pack ages such as ImageM agick, tha t is,animate or convert . For e xample , if y ou sa ve the PPM files star ting with the str ing sequence-2 , and y ou ar e using the ImageM a- gick sof tware, you c an use the convert command with the -adjoin option t o cr eate a single GIF file out of the sequenc e using the f ollowing c ommand . convert -adjoin sequence-2_00*.ppm sequence2.gif 4.Choose the Storage D irectory wher e Fluen t save the anima tion fr ames . 5.(Optional) S pecify the gr aphics Windo w ID wher e the anima tion fr ames will b e displa yed dur ing the c al- cula tion. 6.(Optional) S pecify the Anima tion View, which det ermines the or ientation of the objec t for the anima tion frames c aptur ed dur ing the c alcula tion. You c an onl y sp ecify the vie w onc e an Animation O bjec t is selec ted. Clicking Preview displa ys the selec ted objec t in the gr aphics windo w sp ecified b y Windo w ID , with the view sho wn in the dr op- down. If your desir ed view is not a vailable in the dr op-do wn, you c an pr eview the objec t, change its or ientation in the gr aphics windo w, then click Use A ctive to sa ve the cur rent graphics windo w view and use it f or this anima tion definition. 7.Selec t the gr aphics objec t you w ant to anima te from the Anima tion O bjec t list. If you w ant to anima te an objec t tha t is not list ed, you c an cr eate a New O bjec t. •Mesh... opens the Mesh D ispla y Dialog Box (p.3239 ). •Contours ... opens the Contours D ialog Box (p.3790 ). •Vectors... opens the Vectors D ialog Box (p.3954 ). •Pathlines ... opens the Pathlines D ialog Box (p.3891 ). •Particle Tracks ... opens the Particle Tracks D ialog Box (p.3881 ). •Scene ... opens Figur e 40.26: The Sc ene D ialog Box (p.2812 ). •XY Plot... opens the Solution X Y Plot D ialog Box (p.3703 ). •Rep ort Plot... opens the New R eport Plot D ialog Box (p.3874 ). Note If you selec t residuals , ensur e tha t Plot is enabled in the Residual M onit ors dialo g box. 8.Click OK to create the anima tion definition. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2672Using the S olver37.19.1.1. Guidelines for C reating an A nimation D efinition If you ar e defining an anima tion sequenc e containing mesh, contour, or v ector displa ys, not e the following when y ou ar e defining the displa y: •If you w ant to include ligh ting eff ects in the anima tion fr ames , be sur e to define the ligh ts before you begin the c alcula tion. See Adding Ligh ts (p.2829 ) for inf ormation ab out adding ligh ts to the displa y. •If you w ant to main tain a c onstan t range of c olors in a c ontour or v ector displa y, you c an sp ecify a r ange explicitly b y tur ning off the Auto Range option in the Contours or Vectors dialo g box. See Specifying the R ange of M agnitudes D ispla yed (p.2789 ) or Specifying the R ange of M agnitudes D ispla yed (p.2798 ) for details . •Advanced sc ene manipula tions tha t are sp ecified using the Scene D escr iption dialo g box will not be in- cluded in the anima tion sequenc e frames .View mo dific ations such as mir roring acr oss a symmetr y plan will be included . 37.19.2. Playing an A nima tion S equenc e Onc e you ha ve defined a sequenc e (as descr ibed in Creating an A nima tion D efinition (p.2670 )) and performed a c alcula tion, or r ead in a pr eviously cr eated anima tion sequenc e (as descr ibed in Reading an A nima tion S equenc e (p.2677 )), you c an pla y back the sequenc e using the Playback D ialog Box (p.3679 ) (Figur e 37.42: The P layback D ialog Box (p.2673 )). Results → Anima tions → Solution A nima tion P layback Edit... Figur e 37.42: The P layback D ialo g Box Selec t the anima tion y ou w ant to pla y in the Anima tion S equenc es list. To pla y the anima tion onc e through fr om star t to finish, click the “play” butt on under the Playback heading . (The butt ons func tion 2673Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Anima ting the S olutionin a w ay similar t o those on a standar d video pla yer.“Play” is the sec ond butt on fr om the r ight—a single tr iangle p ointing t o the r ight.) To pla y the anima tion back wards onc e, click the “play reverse ” butt on (the sec ond fr om the lef t—a single tr iangle p oint to the lef t). As the anima tion pla ys, the Frame scale sho ws the numb er of the fr ame tha t is cur rently displa yed, as w ell as its r elative position in the entire anima tion. If, inst ead of pla ying the c omplet e anima tion sequenc e, you w ant to jump t o a par- ticular fr ame , mo ve the Frame slider bar t o the desir ed fr ame numb er, and the fr ame c orresponding to the new fr ame numb er will b e displa yed in the gr aphics windo w. Imp ortant For smo other anima tions , enable the Double Buff ering option in the Displa y Options D ialog Box (p.3681 ) (see Modifying the R ender ing Options (p.2831 )).This will r educ e scr een flick er during gr aphics up dates. Note For HSF F ile and In M emor y 3D anima tions , you c an disable Use S tored View to manipula te the view dur ing pla yback. Additional options f or pla ying back anima tions ar e descr ibed b elow. 37.19.2.1. Mo difying the View If you w ant to repla y the anima tion sequenc e with a diff erent view of the sc ene, you c an use y our mouse t o mo dify (f or e xample , transla te, rotate, zoom) it in the gr aphics windo w wher e the anima tion is displa yed. Note tha t an y changes y ou mak e to the view f or an anima tion sequenc e will b e lost when y ou selec t a new sequenc e (or r eselec t the cur rent sequenc e) in the Sequenc es list. 37.19.2.2. Mo difying the P layback Sp eed Different comput ers will pla y the anima tion sequenc e at diff erent sp eeds , dep ending on the c omple xity of the sc ene and the t ype of har dware used f or gr aphics .You ma y want to slo w do wn the pla yback speed f or optimal viewing . Move the Repla y Speed slider bar t o the lef t to reduc e the pla yback sp eed (and t o the r ight to incr ease it). 37.19.2.3. Playing B ack an E xcerpt You ma y sometimes w ant to pla y only one p ortion of a long anima tion sequenc e.To do this , you c an modify the Start Frame and the End F rame under the Playback heading . For e xample , if y our anim- ation c ontains 50 fr ames , but y ou w ant to pla y only fr ames 20 t o 35, you c an set Start Frame to 20 and End F rame to 35. When y ou pla y the anima tion, it will star t at frame 20 and finish a t frame 35. 37.19.2.4. “Fast-F orwarding ” the A nimation You c an “fast-f orward” or “fast-r everse ” the anima tion b y sk ipping some of the fr ames dur ing pla yback. To fast-f orward the anima tion, you will need t o set the Incr emen t and click the fast-f orward butt on (the last butt on on the r ight—t wo triangles p ointing t o the r ight). If, for e xample , your Start Frame is 1, your End F rame is 15, and y our Incr emen t is 2, when y ou click the fast-f orward butt on, the an- imation will sho w fr ames 1, 3, 5, 7, 9, 11, 13 and 15. Clicking on the fast-r everse butt on (the first butt on on the lef t—t wo triangles p ointing t o the lef t) will sho w fr ames 15, 13, 11,...1. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2674Using the S olver37.19.2.5. Continuous A nimation If you w ant the pla yback of the anima tion t o repeat continuously , ther e ar e two options a vailable . To continuously pla y the anima tion fr om b eginning t o end (or fr om end t o beginning , if y ou use one of the r everse pla y butt ons), selec t Auto Rep eat in the Playback M ode drop-do wn list. To pla y the anima tion back and f orth c ontinuously , reversing the pla yback dir ection each time , selec t Auto Re verse in the Playback M ode drop-do wn list. To tur n off the c ontinuous pla yback, selec t Play Onc e in the Playback M ode list. This is the default setting . 37.19.2.6. Stopping the A nimation To stop the anima tion dur ing pla yback, click the “stop” butt on (the squar e in the middle of the playback c ontrol butt ons). If your anima tion c ontains v ery complic ated sc enes , ther e ma y be a sligh t dela y before the anima tion st ops. 37.19.2.7. Advancing the A nimation F rame b y Frame To ad vance the anima tion manually fr ame b y frame , use the thir d butt on fr om the r ight (a v ertical bar with a tr iangle p ointing t o the r ight). Each time y ou click this butt on, the ne xt frame will b e dis- played in the gr aphics windo w.To reverse the anima tion fr ame b y frame , use the thir d butt on fr om the lef t (a lef t-pointing tr iangle with a v ertical bar). Frame-b y-frame pla yback allo ws you t o freeze the anima tion a t points tha t are of par ticular in terest. 37.19.2.8. Deleting an A nimation S equenc e If you w ant to remo ve one of the sequenc es tha t you ha ve created or r ead in, selec t it in the Sequenc es list and click the Delet e butt on. If you w ant to delet e all sequenc es, click the Delet e All butt on. Imp ortant Note tha t if y ou delet e a sequenc e tha t has not y et b een sa ved t o disk (tha t is, if y ou se- lected In M emor y under Storage Type in the Anima tion S equenc e dialo g box), it will be remo ved fr om memor y permanen tly. If you w ant to keep an y anima tion sequenc es tha t are stored only in memor y, you should b e sur e to sa ve them (as descr ibed in Saving an Anima tion S equenc e (p.2675 )) before you delet e them fr om the Sequenc es list or e xit ANSY S Fluen t. 37.19.3. Saving an A nima tion S equenc e Onc e you ha ve created an anima tion sequenc e, you c an sa ve it in an y of the f ollowing f ormats: •Solution anima tion file c ontaining the ANSY S Fluen t metafiles •Picture files , each c ontaining a fr ame of the anima tion sequenc e •MPEG file c ontaining each fr ame of the anima tion sequenc e 2675Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Anima ting the S olutionNote tha t, if y ou ar e sa ving pic ture files or an MPEG file , you c an mo dify the view (f or e xample , transla te, rotate, zoom) in the gr aphics windo w wher e the anima tion is displa yed, and sa ve the mo dified view instead of the or iginal view . 37.19.3.1. Solution A nimation F ile If you selec ted HSF F ile or PPM Image for Storage Type in Figur e 37.41: The A nima tion D efinition Dialog Box (p.2671 ), then F luen t will sa ve the solution anima tion file f or y ou aut oma tically. It will b e saved in the sp ecified Storage D irectory, and its name will b e the Name you sp ecified f or the se- quenc e, with a .cxa extension (f or e xample ,pressure-contour.cxa ). In addition t o the .cxa file, Fluen t will also sa ve image files with .hsf or .ppm extensions f or each fr ame (f or e xample , pressure-contour_0002.hsf ).The .cxa file c ontains a list of the asso ciated .hsf or .ppm files , and t ells F luen t the or der in which t o displa y them. If you selec ted In M emor y under Storage Type, then the solution anima tion file (.cxa ) and the as- sociated files (.hmf ) will b e lost when y ou e xit fr om ANSY S Fluen t, unless y ou sa ve them as descr ibed below. You c an sa ve the anima tion sequenc e to a file tha t can b e read back in to ANSY S Fluen t (see Reading an A nima tion S equenc e (p.2677 )) when y ou w ant to repla y the anima tion. As not ed in Reading an Anima tion S equenc e (p.2677 ), the solution anima tion file c an b e used f or pla yback in F luen t indep enden t of the c ase and da ta files tha t were used t o gener ate it. To sa ve a solution anima tion file (and the asso ciated files), selec t Anima tion F rames in the Write/Rec ord Format drop-do wn list in the Playback dialo g box, and click the Write butt on. ANSY S Fluen t will sa ve a .cxa file, as w ell as a .hmf file f or each fr ame of the anima tion sequenc e.The fi- lename f or the .cxa file will b e the sp ecified sequenc e Name (for e xample ,pressure-con- tour.cxa ), and the file names f or the metafiles will c onsist of the sp ecified sequenc e Name followed by a fr ame numb er (f or e xample ,pressure-contour_0002.hmf ). All of the files ( .cxa and .hmf ) will b e sa ved in the cur rent working dir ectory. 37.19.3.2. Picture File You c an also gener ate a pic ture file f or each fr ame in the anima tion sequenc e.This f eature allo ws you t o sa ve your sequenc e frames t o pic ture files used b y an e xternal anima tion pr ogram such as ImageM agick. As not ed ab ove, you c an mo dify the view in the gr aphics windo w b efore you sa ve the picture files . To sa ve the anima tion as a ser ies of pic ture files , follow these st eps: 1.Selec t Picture Files in the Write/Rec ord Format drop-do wn list in the Playback dialo g box. 2.If nec essar y, click the Picture Options ... butt on t o op en the Save Picture Dialog Box (p.3676 ) and set the appr opriate par amet ers f or sa ving the pic ture files . (If you ar e sa ving pic ture files f or use with ImageM agick, for e xample , you ma y want to selec t the windo w dump f ormat. See Windo w D umps (Linux S ystems Only) (p.650)Apply in the Save Picture dialo g box to sa ve your mo dified settings . Imp ortant •Do not click the Save... butt on in the Save Picture dialo g box.You will sa ve the pic ture files fr om the Playback dialo g box in the ne xt step. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2676Using the S olver•The AVZ and VRML formats ar e not supp orted f or wr iting solution anima tion pic ture files . 3.In the Playback dialo g box, click the Write butt on. ANSY S Fluen t will r epla y the anima tion, saving each frame t o a separ ate file .The filenames will c onsist of the sp ecified sequenc e Name followed b y an anim- ation sequenc e and a fr ame numb er (f or e xample ,pressure-contour_1_0002.ps ), and the y will all b e sa ved in the cur rent working dir ectory. 37.19.3.3. MP EG F ile It is also p ossible t o sa ve all of the fr ames of the anima tion sequenc e in an MPEG file , which c an b e view ed using an MPEG dec oder such as mpeg_pla y. Saving the en tire anima tion t o an MPEG file will requir e less disk spac e than st oring individual windo w dump files (using the pic ture metho d), but the MPEG file will yield lo wer-qualit y images . As not ed ab ove, you c an mo dify the view in the gr aphics windo w b efore you sa ve the MPEG file . To sa ve the anima tion t o an MPEG file , follow these st eps: 1.Selec t MPEG in the Write/Rec ord Format drop-do wn list in the Playback dialo g box. 2.Click the Write butt on. ANSY S Fluen t will r epla y the anima tion and sa ve each fr ame t o a separ ate scr atch file , and then it will c ombine all the files in to a single MPEG file .The name of the MPEG file will b e the sp ecified sequenc e Name with an .mpg extension (f or e xample ,pressure-contour.mpg ), and it will be sa ved in the cur rent working dir ectory. 37.19.4. Reading an A nima tion S equenc e If you ha ve sa ved an anima tion sequenc e to a solution anima tion file (as descr ibed in Saving an A nim- ation S equenc e (p.2675 )), you c an r ead tha t file back in a t a la ter time (or in a diff erent session) and play the anima tion. Note tha t you c an r ead a solution anima tion file in to an y ANSY S Fluen t session; you do not need t o read in the c orresponding c ase and da ta files . In fac t, you do not need t o read in any case and da ta files a t all b efore you r ead a solution anima tion file in to ANSY S Fluen t. To read a solution anima tion file , click the Read ... butt on in the Playback D ialog Box (p.3679 ). In The Selec t File D ialog Box (p.569), specify the name of the file t o be read. 37.20. Check ing Your C ase S etup After y ou ha ve set up y our c ase, and pr ior t o solving it , you c an check y our c ase setup using the Case Check D ialog Box (p.3647 ) (Figur e 37.43: The C ase C heck D ialog Box (p.2678 )).This func tion pr ovides y ou with guidanc e and b est pr actices when cho osing c ase par amet ers and mo dels .Your c ase will b e check ed for c omplianc e in the mesh, mo dels , boundar y and c ell z one c onditions , ma terial pr operties, and solv er categor ies. Established r ules will b e available f or each c ategor y, with r ecommended changes t o your current settings . At your discr etion, you ma y elec t to apply the r ecommenda tions , or k eep y our cur rent settings . To acc ess the Case C heck D ialog Box (p.3647 ) (Figur e 37.43: The C ase C heck D ialog Box (p.2678 )), go t o 2677Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Check ing Your C ase S etupSolution → Run C alcula tion Check C ase... If ther e ar e no pr oblems with y our c ase setup , then an inf ormation dialo g box (Figur e 37.44: The Inf orm- ation D ialog Box (p.2678 )) will app ear sta ting tha t no r ecommenda tions need t o be made a t this time , other wise , the Case C heck D ialog Box (p.3647 ) will op en. Figur e 37.43: The C ase C heck D ialo g Box Figur e 37.44: The Inf ormation D ialo g Box In the Case C heck dialo g box, each of the tabs Mesh,Models ,Boundar ies and C ell Z ones ,Materials, and Solver ma y contain r ecommenda tions . For each of the tabs tha t are enabled , best pr actices will be list ed. In some c ases , the dialo g box will b e split based on the metho d tha t the r ecommenda tion is applied . There ar e two ways you c an apply the list ed r ecommenda tions: Automa tic Implemen tation ANSY S Fluen t applies the change f or y ou. Manual Implemen tation You will manually change y our c ase settings . For additional inf ormation, see the f ollowing sec tions: 37.20.1. Automa tic Implemen tation 37.20.2. Manual Implemen tation Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2678Using the S olver37.20.1. Automa tic Implemen tation To the lef t of each of the r ecommenda tions list ed under Automa tic Implemen tation (for e xample , Figur e 37.46: The M odels Tab in the C ase C heck D ialog Box (p.2682 )), ther e is an enabled Apply check box. An enabled check b ox will r esult in ANSY S Fluen t applying the change t o your c ase aut oma tically. If ther e ar e some r ecommenda tions tha t you do not w ant ANSY S Fluen t to implemen t aut oma tically, then click the Apply check b ox to toggle off and disable the implemen tation of a par ticular r ecom- menda tion. After going thr ough all the tabs and det ermining which r ules y ou w ant applied aut oma t- ically, click the Apply butt on a t the b ottom of the dialo g box. Changes t o your settings will b e applied to all r ecommenda tions thr oughout the dialo g box with an enabled Apply check b ox. ANSY S Fluen t will print a message in the c onsole notifying y ou tha t the applied r ecommenda tion has b een implemen ted. ANSY S Fluen t will ask y ou if y ou w ant to sa ve the c ase b efore pr oceeding t o the ne xt step. If you choose Yes,The S elec t File D ialog Box (p.569) will op en allo wing y ou t o sa ve your c ase with the new settings . If you selec t No, all the changes made t o the c ase file will b e lost onc e you e xit ANSY S Fluen t. 37.20.2. Manual Implemen tation For recommenda tions tha t are list ed under Manual Implemen tation , ANSY S Fluen t cannot apply the changes f or y ou.Therefore, if y ou opt t o mak e a change t o your cur rent settings , based on the list ed recommenda tions , then y ou will need t o manually mak e the changes b y op ening the aff ected dialo g boxes or task pages and applying wha t was recommended . To the r ight of the r ecommenda tions is a ?, which essen tially ac ts as a help butt on, leading y ou t o related do cumen tation on the sp ecific t opic . At the b ottom of each r ecommenda tion, ther e is a pa th tha t will guide y ou t o the dialo g box or task page wher e you c an mak e the changes . For e xample , in the Mesh tab , you will see the f ollowing r e- commenda tion: Check your mesh. (General: Click [Check]) To perform the ac tion, highligh t Gener al in the tr ee, then click the Check butt on in the Mesh group box.You will see a pa th for each r ecommenda tion, in each of the tabs . Each of the c ase check r ules ar e descr ibed in the f ollowing sec tions: 37.20.2.1. Check ing the M esh 37.20.2.2. Check ing M odel S elec tions 37.20.2.3. Check ing B oundar y and C ell Z one C onditions 37.20.2.4. Check ing M aterial P roperties 37.20.2.5. Check ing the S olver Settings 2679Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Check ing Your C ase S etup37.20.2.1. Check ing the Mesh Figur e 37.45: The M esh Tab in the C ase C heck D ialo g Box The f ollowing r ecommenda tions app ear under the Mesh tab ( Figur e 37.45: The M esh Tab in the C ase Check D ialog Box (p.2680 )): •Check y our mesh. If you ha ve not alr eady check ed y our mesh, it is b est pr actice tha t you do so immedia tely af ter reading in y our mesh, or af ter an y mesh mo dific ation. To check y our mesh go t o Setup → Gener al → Check Check ing the mesh will help y ou det ect an y mesh tr ouble b efore you get star ted with y our pr oblem setup .You c an lear n mor e ab out the inf ormation obtained when check ing y our mesh, by going t o Check ing the M esh (p.788). •Impr ove the mesh qualit y before pr oceeding with y our simula tion. The maximum c ell sk ewness is greater than 0.98. Check the qualit y of y our mesh immedia tely af ter reading in y our mesh, or af ter an y mesh mo dific- ation. The qualit y of the mesh pla ys a signific ant role in the accur acy and stabilit y of the numer ical computa tion. You c an lear n mor e ab out the qualit y of y our mesh b y going t o Mesh Q ualit y (p.719). Setup → Gener al → Rep ort Qualit y •Preview zone motion and mesh motion b efore beginning the simula tion. After setting up y our c ase using the Dynamic M esh mo del, it is w orth while t o pr eview y our mesh prior t o running y our simula tion. You c an pr eview Zone M otion by going t o Setup → Dynamic M esh → Dynamic M esh → Displa y Zone M otion... To pr eview the Mesh M otion , go t o Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2680Using the S olverSetup → Dynamic M esh → Dynamic M esh → Preview M esh M otion... or Solution → Run C alcula tion Preview M esh M otion... or Solution → Run C alcula tion → Preview M esh M otion... It is imp ortant tha t you pr eview z one motion first and then mesh motion. Zone motion sho ws the motion of all d ynamic z ones with the pr escr ibed r igid b ody motion, using the gr aphics libr ary. It is a v ery fast pr ocess and do es not alt er the mesh. Previewing the z one motion will sho w you if the motion is set up pr operly (for e xample z ones mo ving in the wr ong dir ection or r otating ab out the wr ong c enter). It is much mor e difficult t o det ect these pr oblems with mesh motion b ecause small time st eps ar e performed and no c ontinuous anima tion is sho wn. Mesh motion should alw ays be done f or d ynamic mesh c ases with pr escr ibed motion. Mesh motion will only sho w the v alidit y of the mesh dur ing the simula tion. Mesh def ormation and d ynamic zones without r igid b ody motion will b e consider ed dur ing a mesh motion pr eview . Both the Mesh M otion and Zone M otion dialo g boxes will ha ve a Preview butt on tha t will allo w you t o view the mesh or z one motion pr ior t o running y our c ase.You c an obtain mor e inf ormation on mesh motion and z one motion b y going t o Previewing the D ynamic M esh (p.1368 ). •Transla te the mesh f or axisymmetr ic geometr y containing no des b elow the x-axis . If either Axisymmetr ic or Axisymmetr ic S wirl is sp ecified in the Gener al task page and ther e ar e mesh no des tha t fall b elow the x-axis , then it is r ecommended tha t you tr ansla te the mesh. Nodes below the axis ar e forbidden f or axisymmetr ic cases , sinc e the axisymmetr ic cell v olumes ar e created b y rotating the 2D c ell v olume ab out the axis; ther efore no des b elow the axis w ould create nega tive volumes .To find out if ther e ar e an y no des tha t lie b elow the x-axis , perform a mesh check ( Check ing the M esh (p.788)). For inf ormation on tr ansla ting the mesh, see Transla ting the M esh (p.824).To acc ess the Mesh Transla te dialo g box, go t o Domain → Mesh → Transf orm → Transla te... 2681Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Check ing Your C ase S etup37.20.2.2. Check ing Mo del S elec tions Figur e 37.46: The M odels Tab in the C ase C heck D ialo g Box The f ollowing r ecommenda tions app ear under the Models tab ( Figur e 37.46: The M odels Tab in the Case C heck D ialog Box (p.2682 )): •Consider r ealizable k-epsilon in lieu of the standar d k-epsilon turbulenc e mo del. The r ealizable - mo del is a mor e recent de velopmen t of the standar d - mo del and diff ers from it in tha t the r ealizable - mo del c ontains a new f ormula tion f or the turbulen t visc osity, as well as a new tr ansp ort equa tion f or the dissipa tion r ate, , der ived fr om an e xact equa tion f or the transp ort of the mean-squar e vorticit y fluc tuation. realizable - mo del means tha t the mo del sa tisfies c ertain ma thema tical constr aints on the Reynolds str esses , consist ent with the ph ysics of turbulen t flo ws. For mor e inf ormation on the standar d - mo del and the r ealizable - mo del, visit Standar d k-ε Model and Realizable k- ε Model (in the Theor y Guide ), respectively. Setup → Models → Visc ous → Edit... For inf ormation on all - mo del options , go t o Standar d, RNG, and R ealizable k- ε Models in the Theor y Guide . •Disable DO/E nergy coupling if the optic al thick ness is less than 10. DO/Ener gy coupling should only b e used when the optic al thick ness is gr eater than 10. Refer to Ener gy Coupling and the DO M odel in the Theor y Guide for mor e inf ormation. Setup → Models → Radia tion → Edit... •Verify tha t the t emp erature sp ecified f or b oundar y zones tha t do not par ticipa te in the vie w fac tor calcula tion is appr opr iate. When using the S2S r adia tion mo del, mak e sur e tha t you set the t emp erature for b oundar ies tha t do not par ticipa te in the view fac tor c alcula tion t o an appr opriate value . In most c ases the appr o- Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2682Using the S olverpriate value is the ambien t temp erature, which b y default is assumed t o be 300 K. See Specifying Boundar y Zone P articipa tion (p.1503 ) for mor e inf ormation. Setup → Models → Radia tion → Edit... •Change the under-r elaxa tion fac tor f or the mixing plane mo del t o 1.0. If you ha ve created a mixing plane , set the Under-Relaxa tion in the Mixing P lane dialo g box to 1. Look under G lobal P aramet ers in Setting U p the M ixing P lane M odel (p.1243 ) for inf ormation about the mixing plane under-r elaxa tion. Domain → Mesh M odels → Mixing P lanes ... •Enable the smo othing option f or d ynamic mesh simula tions when r emeshing . When y our c ase in volves the use of d ynamic meshes and r emeshing is enabled , then it is r ecom- mended tha t you also p erform smo othing on the mesh. For a c omplet e discussion of smo othing and r emeshing , see Setting D ynamic M esh M odeling P aramet ers (p.1266 ). Setup → Dynamic M esh → Dynamic M esh •Disable sp ecies inlet diffusion f or laminar flo w with sp ecies tr ansp ort. By default , ANSY S Fluen t includes the diffusion flux of sp ecies a t inlets . In some c ases in volving species tr ansp ort and laminar flo w, it is r ecommended tha t the Inlet D iffusion option in the Species Model dialo g box is disabled . For e xample , –If you w ant to include only the c onvective transp ort of sp ecies thr ough the inlets of y our domain. –If at one of the inlets , the c onvective flux is v ery small, resulting in mass loss b y diffusion thr ough the inlet. Setup → Models → Species → Edit... For mor e inf ormation ab out diffusion a t inlets , go t o Defining C ell Z one and B oundar y Conditions for S pecies (p.1649 ). •Include turbulenc e in teraction f or the NO x mo del. When r unning ther mal NO x simula tions and y our flo w is turbulen t, then b e sur e to set the NO x Turbulenc e In teraction M ode. Setup → Models → NOx → Edit... In turbulen t combustion c alcula tions , ANSY S Fluen t solv es the densit y-weigh ted time-a veraged Navier-S tokes equa tions f or temp erature, velocity, and sp ecies c oncentrations or mean mix ture fraction and v arianc e. Metho ds of mo deling the mean turbulen t reaction r ate can b e based on either momen t metho ds or pr obabilit y densit y func tion (PDF) t echniques . ANSY S Fluen t uses the PDF appr oach. To lear n ab out ho w this f eature is set up , go t o Setting Turbulenc e Paramet ers (p.1836 ). •Consider using the default Schner r-Sauer or the Z wart-Gerb er-B elamr i cavita tion mo del. 2683Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Check ing Your C ase S etupWhen using the mix ture multiphase mo del with the S inghal et al. cavitation mo del enabled , consider changing it t o either the Schner r-Sauer or the Z wart-Gerber-B elamr i cavitation mo del. Refer to Cavitation M odels in the Theor y Guide f or mor e inf ormation. Setup → Models → Phases → Interaction... 37.20.2.3. Check ing B oundar y and C ell Z one C onditions Figur e 37.47: The B oundar ies and C ell Z ones Tab in the C ase C heck D ialo g Box The f ollowing r ecommenda tions app ear under the Boundar ies and C ell Z ones tab ( Figur e 37.47: The Boundar ies and C ell Z ones Tab in the C ase C heck D ialog Box (p.2684 )): •Apply an axis b oundar y on the c enterline (x-axis). For geometr y tha t is axisymmetr ic or axisymmetr ic swir l (as set in the Gener al task page), the centerline (x-axis) b oundar y type should b e set t o axis . See Axis B oundar y Conditions (p.1002 ). Boundar y Conditions •Change outlet b oundar y conditions . A c ombina tion of pr essur e and outflo w b oundar ies is not compa tible . Outflo w b oundar y conditions in ANSY S Fluen t are used t o mo del flo w exits wher e the details of the flo w velocity and pr essur e ar e not k nown pr ior t o solution of the flo w pr oblem. One of the limita tions when using outflo w b oundar y conditions is tha t outflo w b oundar y conditions ar e not compa tible with pr essur e inlets .Therefore, it is r ecommended tha t you use v elocity or mass-flo w inlets inst ead of pr essur e inlets when used in c ombina tion with outflo w b oundar ies. See Outflo w Boundar y Conditions (p.963) for a list of limita tions tha t exist with outflo w b oundar ies. Setup → Boundar y Conditions •Change outlet b oundar y conditions . Outflo w b oundar y conditions ar e not c ompa tible with the ideal gas la w for densit y. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2684Using the S olverOutflo w b oundar ies c annot b e used if y ou ar e mo deling unst eady flo ws with v arying densit y, even if the flo w is inc ompr essible . See Outflo w Boundar y Conditions (p.963) for mor e limita tions tha t exist with outflo w b oundar ies. Setup → Boundar y Conditions •Non-z ero op erating pr essur e set .This will b e added t o gauge pr essur e inputs . For c ases tha t ha ve densit y sp ecified as the ideal gas la w, and the op erating pr essur e is gr eater than z ero, the op erating pr essur e will b e added t o the gauge pr essur e to yield the absolut e pr essur e. For mor e inf ormation, see Densit y Inputs f or the Ideal G as La w for C ompr essible F lows (p.1105 ) and Operating P ressur e, Gauge P ressur e, and A bsolut e Pressur e (p.1153 ). Setup → Boundar y Conditions → Operating C onditions ... •Apply p ositiv e non-z ero pr essur e boundar y conditions when using the ideal gas la w for densit y. In compr essible flo ws , isen tropic r elations f or an ideal gas ar e applied t o relate total pr essur e, static pr essur e, and v elocity at a pr essur e inlet b oundar y.Your input of t otal pr essur e, , at the inlet and the sta tic pr essur e, , in the adjac ent fluid c ell ar e related, as descr ibed in Equa- tion 7.87 (p.928)Equa tion 7.88 (p.928) of Calcula tion P rocedur e at Pressur e Inlet B oundar ies (p.927). It is r ecommended tha t pressur e boundar y conditions ar e not set t o zero for c ompr essible flo ws that use the ideal gas la w. Setup → Boundar y Conditions •Review turbulenc e sp ecific ations a t flo w b oundar ies. Default v alues det ected. If your c ase setup has an y of the turbulenc e mo dels enabled , be sur e to review the default par a- met ers f or K and E psilon or K and Omega for the Turbulenc e Specific ation M etho d in the outlet and inlet b oundar y conditions . ANSY S Fluen t’s default par amet ers f or the ( Backflo w) Turbulen t Kinetic E nergy, (Backflo w) Turbulen t Dissipa tion R ate, and ( Backflo w) Specific D issipa tion R ate are 1.You c an either adjust the v alues , or selec t a diff erent Turbulenc e Specific ation M etho d. For gener al inf ormation turbulenc e par amet ers, see Determining Turbulenc e Paramet ers (p.914). Setup → Boundar y Conditions •Assign non-z ero la yer thick nesses f or w all b oundar ies with shell c onduc tion. When the Shell C onduc tion option is enabled in the Wall boundar y condition dialo g box, ANSY S Fluen t will c omput e hea t conduc tion f or the w all not only in the nor mal dir ection, but also in the planar dir ections .To enable such c omputa tions , you must sp ecify a nonz ero Thick ness for each layer in the Shell C onduc tion L ayers dialo g box. See Shell C onduc tion (p.989) for inf ormation on shell c onduc tion in thin w alls. Setup → Boundar y Conditions •Assign a v alue of 0 or 1 f or VOF a t the inlet or outlet b oundar y conditions . When enabling the VOF mo del, the Volume F raction in the inlet and outlet b oundar y conditions for each phase should b e set either t o 0 or 1. No in termedia te values ar e permitt ed. For gener al 2685Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Check ing Your C ase S etupinformation on b oundar y condition setup , see Defining M ultiphase C ell Z one and B oundar y Condi- tions (p.2124 ). Setup → Boundar y Conditions •Change the outlet b oundar y condition. Outflo w b oundar y condition is not c ompa tible with cur rent multiphase settings . You c annot assign an outflo w b oundar y condition when using the mix ture and E uler ian multiphase models . Note the limita tions of this b oundar y condition in Outflo w Boundar y Conditions (p.963). ANSY S Fluen t can mo del the eff ects of op en channel flo w using the VOF f ormula tion. In such a case, outflo w b oundar y conditions c an b e used a t the outlet of op en channel flo ws, to mo del flo w exits wher e the details of the flo w velocity and pr essur e ar e not k nown pr ior t o solving the flo w problem. See Open C hannel F low in the Theor y Guide , under the heading Outflo w Boundar y, for mor e inf ormation. Setup → Boundar y Conditions •Review w all motion. Stationar y wall motion r elative to adjac ent cell z one det ected. In cases wher e the fluid z one motion t ype is sp ecified as Moving M esh or Moving Ref erenc e Frame , all w all z ones should b e set t o Moving Wall in the Momen tum tab in the Wall boundar y conditions dialo g box.The w all motion should b e defined Rela tive to Adjac ent Cell Z one .The exception t o this is if the w alls ar e sta tionar y in the absolut e frame .To define w all motion, see Inputs at Wall B oundar ies (p.971). Setup → Boundar y Conditions •Assign non-z ero velocities when sp ecifying a mo ving fluid z one . If selec ting either Moving M esh or Moving Ref erenc e Frame in the Fluid dialo g box, be sur e to set nonz ero values f or the r otational and tr ansla tional v elocities . Refer to Defining Z one M o- tion (p.857) for user inputs . Setup → Cell Z one C onditions •Review flo w sp ecific ations a t inlet b oundar ies. Default v alues det ected. For mass-flo w-inlet and velocity-inlet boundar y conditions , the default v alues in ANSY S Fluen t are and , respectively. Review the settings and adjust acc ordingly . See Default S ettings at Velocity Inlet B oundar ies (p.933) and Default S ettings a t Mass-F low Inlet B oundar ies (p.941) for default par amet ers of v elocity inlets and mass-flo w inlets , respectively. Setup → Boundar y Conditions •Define the p orous z one when using the hea t exchanger mo del. Heat exchanger mo dels alw ays requir e the definition of the p orous media z one on the pr imar y side f or the macr o mo del and f or b oth pr imar y and auxiliar y sides f or the dual c ell mo del. See Streamwise P ressur e Drop in the Theor y Guide for mor e inf ormation. Setup → Cell Z one C onditions Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2686Using the S olver37.20.2.4. Check ing M aterial P roperties Figur e 37.48: The M aterials Tab in the C ase C heck D ialo g Box The f ollowing r ecommenda tions app ear under the Materials tab ( Figur e 37.48: The M aterials Tab in the C ase C heck D ialog Box (p.2687 )): •Assign individual fluid Cps t o polynomial func tions of t emp erature. For c ases with sp ecies tr ansp ort and v olumetr ic reactions , it is b est pr actice to sp ecify the sp ecific heat capacit y as a p olynomial tha t is a func tion of t emp erature. See Defining P roperties f or the Mixture and I ts C onstituen t Species (p.1629 ) and Specific H eat Capacit y as a F unction of Temp erat- ure (p.1136 ) for inf ormation on defining ma terial pr operties f or the sp ecies in the mix ture. Setup → Materials •Assign a non-z ero value f or the densit y when selec ting b oussinesq . The B oussinesq mo del is used f or na tural convection pr oblems in volving small changes in t emp er- ature.To enable the B oussinesq appr oxima tion f or densit y, cho ose boussinesq from the Densit y drop-do wn list in the Create/Edit M aterials dialo g box and sp ecify a c onstan t value f or Densit y. See Inputs f or the B oussinesq A pproxima tion (p.1100 ). Setup → Materials •Review the absor ption c oefficien t. Default v alue det ected. If an y of the r adia tion mo dels ar e enabled . Enter an absor ption c oefficien t for the ma terial list ed (Radia tion P roperties (p.1137 )). Setup → Materials •Assign a non-z ero ther mal e xpansion c oefficien t when selec ting the B oussinesq densit y mo del. 2687Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Check ing Your C ase S etupWhen selec ting boussinesq to descr ibe the densit y of y our ma terial, be sur e to en ter a v alid ther mal expansion c oefficien t for y our ma terial. For detailed inf ormation on the B oussinesq mo del, see The Boussinesq M odel (p.1476 ). Setup → Materials 37.20.2.5. Check ing the S olver S ettings Figur e 37.49: The S olver Tab in the C ase C heck D ialo g Box The f ollowing r ecommenda tions app ear under the Solver tab ( Figur e 37.49: The S olver Tab in the Case C heck D ialog Box (p.2688 )): •Enable the unst ead y solv er option when selec ting mo ving mesh f or the fluid b oundar y. If the motion t ype of the fluid b oundar y condition is sp ecified as Moving M esh, then y our c ase should b e sp ecified as Transien t in the Gener al task page .Visit Setting U p the S liding M esh Problem (p.1258 ) for st eps on setting up mo ving mesh pr oblem. Setup → Gener al •Assign LSQ c ell-based gr adien t reconstr uction. The least squar es c ell-based a veraging scheme is k nown t o be as accur ate as the no de-based gradien t for ir regular unstr uctured meshes , but less e xpensiv e to comput e than the no de-based gradien t.Therefore, it is r ecommended tha t least squar es c ell-based gr adien t reconstr uction is used . See Evalua tion of G radien ts and D erivatives in the Theor y Guide for mor e inf ormation on gr adien t options . Solution → Metho ds •Change the under-r elaxa tion fac tor f or the ener gy equa tion t o at least 0.90. You should set the ener gy under-r elaxa tion fac tor b etween 0.90 and 1.0. If you decide t o apply this r ecommenda tion, then ANSY S Fluen t will aut oma tically set the ener gy under-r elaxa tion fac tor Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2688Using the S olverto 0.90 . If you w ant to incr ease this v alue , you c an manually mak e the change b y going t o the Solution C ontrols task page . See Solution S trategies f or H eat Transf er M odeling (p.1470 ) for the under-r elaxa tion of the ener gy equa tion. Solution → Controls •Incr ease the NO x under-r elaxa tion fac tor t o at least 0.90. If the NO x mo del is enabled , set the NO x under-r elaxa tion fac tor to a v alue of a t least 0.90 t o fully converge the solution. Note tha t the under-r elaxa tion fac tor c ould b e lower a t the star t of the r un, but c an then b e incr eased af ter an initial solution is obtained . If you decide t o apply this r ecom- menda tion, then ANSY S Fluen t will aut oma tically set the NO x under-r elaxa tion fac tor to 0.90 . If you w ant to incr ease this v alue , you c an manually mak e the change b y going t o the Solution Controls task page . See Using the NO x Model (p.1823 ). Solution → Controls •Incr ease the D iscr ete Or dina tes under-r elaxa tion fac tor t o at least 0.90. If the D iscrete Or dina tes (DO) r adia tion mo del is enabled , set the r adia tion under-r elaxa tion fac tor to a v alue of a t least 0.90 t o fully c onverge the solution. Note tha t the under-r elaxa tion fac tor c ould be lower a t the star t of the r un, but c an then b e incr eased af ter an initial solution is obtained . If you decide t o apply this r ecommenda tion, then ANSY S Fluen t will aut oma tically set the r adia tion under-r elaxa tion fac tor to 0.90 . If you w ant to incr ease this v alue , you c an manually mak e the change b y going t o the Solution C ontrols task page . See DO S olution P aramet ers (p.1534 ). Solution → Controls •Incr ease the P1 under-r elaxa tion fac tor t o 1.0. If the P1 r adia tion mo del is enabled , set the r adia tion under-r elaxa tion fac tor to 1.0 t o fully c onverge the solution. Note tha t the under-r elaxa tion fac tor c ould b e lower a t the star t of the r un, but c an then b e incr eased af ter an initial solution is obtained . If you decide t o apply this r ecommenda tion, then ANSY S Fluen t will aut oma tically set the r adia tion under-r elaxa tion fac tor to 1.0 . See P-1 Model S olution P aramet ers (p.1532 ). Solution → Controls •Incr ease the sp ecies and ener gy under-r elaxa tion fac tors t o at least 0.90. For a c ase with sp ecies tr ansp ort and ener gy defined , set the sp ecies and ener gy under-r elaxa tion factors t o a v alue of a t least 0.90. If you decide t o apply this r ecommenda tion, then ANSY S Fluen t will automa tically set the sp ecies and ener gy under-r elaxa tion fac tors t o 0.90 . If you w ant to incr ease this v alue , you c an manually mak e the change b y going t o the Solution C ontrols task page . See Solution P rocedur es for C hemic al M ixing and F inite-Rate Chemistr y (p.1650 ). Solution → Controls •Assign a v alue of 1 f or the under-r elaxa tion fac tor f or unst ead y DPM with 1 DPM up date per time step. 2689Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Check ing Your C ase S etupIt is r ecommended tha t the DPM under-r elaxa tion fac tor b e set t o 1 f or unst eady DPM with 1 DPM update per time st ep. Solution → Controls •Incr ease the mean mix ture fraction under-r elaxa tion fac tor t o at least 0.90. If the non-pr emix ed or par tially pr emix ed c ombustion mo dels ar e enabled , then it is b est t o set the mean mix ture under-r elaxa tion fac tor to a v alue of a t least 0.90 t o ensur e full c onvergenc e. If you decide t o apply this r ecommenda tion, then ANSY S Fluen t will aut oma tically set the mean mixture under-r elaxa tion fac tor to 0.90 . If you w ant to incr ease this v alue , you c an manually mak e the change b y going t o the Solution C ontrols task page . See Solving the F low Problem (p.1743 ). Solution → Controls •Consider using higher or der discr etiza tion f or impr oved accur acy of the final solution. First-or der discr etiza tion ma y be used in the initial solution. It is gener ally ad visable t o obtain an initial solution using first-or der accur ate discr etiza tion, however, second or der discr etiza tion is r ecommended f or impr oved accur acy of the final solution. See Choosing the S patial D iscretiza tion Scheme (p.2562 ) for mor e inf ormation on discr etiza tion schemes . Solution → Metho ds •Selec t the absolut e referenc e frame f or initializing c ases when using the MRF mo del. When using the MRF mo del, alw ays use the absolut e reference frame while initializing the solution. Selec t Absolut e under Referenc e Frame in the Solution Initializa tion task page . If the Rela tive to Cell Z one option is selec ted, which is the default option, the initial flo w field c an c ontain disc on- tinuities , which c an c ause c onvergenc e pr oblems in the first f ew it erations . Refer to Initializing the Entire Flow Field U sing S tandar d Initializa tion (p.2605 ) for mor e inf ormation. Solution → Initializa tion Initializ e •Choose PREST O! f or the pr essur e discr etiza tion scheme . When using the VOF mo del, it is r ecommended tha t you use PREST O! as the pr essur e discr etiza tion scheme .This scheme is r ecommended f or flo ws with high swir l numb ers, a high-R ayleigh-numb er natural convection, high-sp eed r otating flo ws, flows involving p orous media, and flo ws in str ongly curved domains . See Choosing the P ressur e In terpolation Scheme (p.2564 ) for mor e inf ormation. Solution → Metho ds 37.21. Convergenc e and S tabilit y Convergenc e can b e hinder ed b y a numb er of fac tors. Large numb ers of c omputa tional c ells, overly conser vative under-r elaxa tion fac tors, and c omple x flo w ph ysics ar e of ten the main c auses . Sometimes it is difficult t o know whether y ou ha ve a c onverged solution. In the f ollowing sec tions , some of the numer ical controls and mo deling t echniques tha t can b e exercised t o enhanc e convergenc e and main tain stabilit y are examined . 37.21.1. Judging C onvergenc e Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2690Using the S olver37.21.2. Step-b y-Step S olution P rocesses 37.21.3. Modifying A lgebr aic M ultigr id Paramet ers 37.21.4. Modifying the M ulti-S tage P aramet ers 37.21.5. Robustness on M eshes of P oor Q ualit y 37.21.6. Warped-F ace Gradien t Correction You should also r efer to Choosing the S patial D iscretiza tion Scheme (p.2562 ) and Choosing the P ressur e- Velocity Coupling M etho d (p.2570 ) for inf ormation ab out ho w the choic e of discr etiza tion scheme or (f or the pr essur e-based solv er) pr essur e-velocity coupling scheme c an aff ect convergenc e. Manipula tion of under-r elaxa tion par amet ers and multigr id settings t o enhanc e convergenc e is discussed in Setting Under-R elaxa tion F actors (p.2573 ) and Modifying A lgebr aic M ultigr id P aramet ers (p.2693 ). 37.21.1. Judging C onvergenc e There ar e no univ ersal metr ics f or judging c onvergenc e. Residual definitions tha t are useful f or one class of pr oblem ar e sometimes misleading f or other classes of pr oblems .Therefore it is a go od idea to judge c onvergenc e not only b y examining r esidual le vels, but also b y monit oring r elevant integrated quan tities such as dr ag or hea t transf er coefficien t. For man y pr oblems , the default c onvergenc e cr iterion in ANSY S Fluen t is sufficien t.This cr iterion r equir es that the globally sc aled r esiduals , defined b y Equa tion 37.9 (p.2647 ) or Equa tion 37.15 (p.2649 ) decr ease to for all equa tions e xcept the ener gy and P-1 equa tions , for which the cr iterion is . Sometimes , however, this cr iterion ma y not b e appr opriate. For e xample: •Because the c ontinuit y residual is sc aled b y its b ehavior dur ing the first fiv e iterations , the c ontinuit y residual level is initial guess-dep enden t and star tup-dep enden t. A b etter initial guess ma y lead t o a higher c ontinuit y residual, which is c oun ter-in tuitiv e for judging c onvergenc e. •Because the global sc ale fac tors dep end on the solution le vel, sometimes the r esiduals ar e signific antly below the default c onvergenc e tar get e ven when the solution is still changing .This b ehavior o ccurs most frequen tly with the ener gy equa tion. •For some equa tions , such as f or turbulenc e quan tities , a poor initial guess ma y result in high sc ale fac tors. In such c ases , scaled r esiduals will star t low, incr ease as nonlinear sour ces build up , and e ventually decr ease . It is ther efore go od pr actice to judge c onvergenc e not just fr om the v alue of the r esidual itself , but fr om its b ehavior.You should ensur e tha t the r esidual c ontinues t o decr ease (or r emain lo w) for se veral iterations (say 50 or mor e) b efore concluding tha t the solution has c onverged . When issues lik e the ab ove ar ise, you should c onsider using lo cally sc aled r esiduals defined b y Equa- tion 37.10 (p.2648 ) or Equa tion 37.16 (p.2649 ), which ha ve a default c onvergenc e cr iterion of 10-5 for all equa tions . Exp erienc e suggests tha t locally sc aled r esiduals ma y be mor e univ ersal f or the pur poses of judging c onvergenc e than globally sc aled r esiduals . Another p opular appr oach t o judging c onvergenc e is t o requir e tha t the unsc aled r esiduals dr op b y three or ders of magnitude . ANSY S Fluen t provides r esidual nor maliza tion f or this pur pose, as discussed in Definition of R esiduals f or the P ressur e-Based S olver (p.2647 ), wher e residuals ar e defined f or b oth the pr essur e-based solv er and the densit y-based solv er. In this appr oach the c onvergenc e cr iterion is that the nor maliz ed unsc aled r esiduals should dr op t o . However, this r equir emen t ma y not b e appr opriate in man y cases: 2691Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Convergenc e and S tabilit y•If you ha ve pr ovided a v ery go od initial guess , the r esiduals ma y not dr op thr ee or ders of magnitude . In a near ly-isother mal flo w, for e xample , ener gy residuals ma y not dr op thr ee or ders if the initial guess of temp erature is v ery close t o the final solution. •If the go verning equa tion c ontains nonlinear sour ce terms which ar e zero at the b eginning of the c alcula tion and build up slo wly dur ing c omputa tion, the r esiduals ma y not dr op thr ee or ders of magnitude . In the case of na tural convection in an enclosur e, for e xample , initial momen tum r esiduals ma y be very close t o zero because the initial unif orm temp erature guess do es not gener ate buo yancy. In such a c ase, the initial near ly-zero residual is not a go od sc ale f or the r esidual. •If the v ariable of in terest is near ly zero everywher e, the r esiduals ma y not dr op thr ee or ders of magnitude . In fully-de velop ed flo w in a pip e, for e xample , the cr oss-sec tional v elocities ar e zero. If these v elocities ha ve been initializ ed t o zero, initial (and final) r esiduals ar e both close t o zero, and a thr ee-or der dr op c annot be expected. Regar dless of the r esidual sc aling metho d, it is wise t o monit or imp ortant solution quan tities , such as drag or o verall hea t transf er coefficien t, before concluding tha t the solution has c onverged . Conversely , it is p ossible tha t if the initial guess is v ery bad , the initial r esiduals ar e so lar ge tha t a three-or der dr op in r esidual do es not guar antee c onvergenc e.This is sp ecially tr ue f or and equa tions wher e go od initial guesses ar e difficult. Here again it is useful t o examine o verall in tegrated quan tities that you ar e par ticular ly in terested in. If the solution is unc onverged , you ma y dr op the c onvergenc e toler ance, as descr ibed in Modifying C onvergenc e Criteria (p.2654 ). 37.21.2. Step-b y-Step S olution P rocesses One imp ortant technique f or sp eeding c onvergenc e for c omple x pr oblems is t o tack le the pr oblem one st ep a t a time .When mo deling a pr oblem with hea t transf er, you c an b egin with the c alcula tion of the isother mal flo w.To solv e turbulen t flo w, you migh t star t with the c alcula tion of laminar flo w. When mo deling a r eacting flo w, you c an b egin b y computing a par tially c onverged solution t o the non-r eacting flo w, possibly including the sp ecies mixing .When mo deling a discr ete phase , such as fuel e vaporating fr om dr oplets , it is a go od idea t o solv e the gas-phase flo w field first. Such solutions gener ally ser ve as a go od star ting p oint for the c alcula tion of the mor e comple x pr oblems .These st ep- by-step t echniques in volve using the Solution C ontrols Task P age (p.3606 ) to tur n equa tions on and off in the Equa tions dialo g box. 37.21.2.1. Selec ting a S ubset of the S olution E quations ANSY S Fluen t aut oma tically solv es each equa tion tha t is tur ned on using the Models family of dialo g boxes. If you sp ecify in the Viscous M odel D ialog Box (p.3253 ) tha t the flo w is turbulen t, equa tions f or conser vation of turbulenc e quan tities ar e tur ned on. If you sp ecify in the Ener gy Dialog Box (p.3252 ) that ANSY S Fluen t should enable ener gy, the ener gy equa tion is enabled . Convergenc e can b e sp ed up b y focusing the c omputa tional eff ort on the equa tions of pr imar y imp ortanc e.The Equa tions list in the Equa tions D ialog Box (p.3609 ) allo ws you t o tur n individual equa tions on or off t emp orarily. Solution → Controls Equa tions ... A typic al example is the c omputa tion of a flo w with hea t transf er. Initially , you will define the full problem sc ope, including the ther mal b oundar y conditions and t emp erature-dep enden t flo w pr operties. Following the pr oblem setup , you will use the Equa tions dialo g box to temp orarily tur n off the ener gy Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2692Using the S olverequa tion. You c an then c omput e an isother mal flo w field , rememb ering t o set a r easonable initial value f or the t emp erature of the fluid . Imp ortant This is p ossible only f or the pr essur e-based solv er; the densit y-based solv er solv es the ener gy equa tion t ogether with the flo w equa tions in a c oupled manner , so y ou c annot tur n off the ener gy equa tion as descr ibed ab ove. When the isother mal flo w is r easonably w ell c onverged , you c an tur n the ener gy equa tion back on. You c an ac tually tur n off the momen tum and c ontinuit y equa tions while the initial ener gy field is being c omput ed.When the ener gy field b egins t o converge w ell, you c an tur n the momen tum and continuit y equa tions back on so tha t the flo w pa ttern can adjust t o the new t emp erature field .The temp erature will c ouple back in to the flo w solution b y its impac t on fluid pr operties such as densit y and visc osity.The t emp erature field will ha ve no eff ect on the flo w field if the fluid pr operties (f or example , densit y, visc osity) do not v ary with t emp erature. In such c ases , you c an c omput e the ener gy field without tur ning the flo w equa tions back on again. Imp ortant If you ha ve sp ecified t emp erature-dep enden t flo w pr operties, you should b e sur e tha t a realistic v alue has b een set f or temp erature thr oughout the domain b efore disabling c al- cula tion of the ener gy equa tion. If an unr ealistic t emp erature value is used , the flo w properties dep enden t on t emp erature will also b e unr ealistic , and the flo w field will b e adversely aff ected. Instr uctions f or initializing the t emp erature field or pa tching a t emp er- ature field on to an e xisting solution ar e pr ovided in Initializing the S olution (p.2604 ). 37.21.2.2. Turning R eac tions O n and O ff To solv e a sp ecies mixing pr oblem pr ior t o solving a r eacting flo w, you should set up the pr oblem including all of the r eaction inf ormation, and sa ve the c omplet e case file .To tur n off the r eaction so that only the sp ecies mixing pr oblem c an b e solv ed, you c an use the Species M odel D ialog Box (p.3294 ) to tur n off the Volumetr ic option under Reac tions . Setup → Models → Species → Edit... Onc e the sp ecies mixing pr oblem has par tially c onverged , you c an r etur n to the Species M odel dialo g box and tur n the Volumetr ic Reac tions option on again. You c an then r esume the c alcula tion star ting from the par tially c onverged da ta. For c ombustion pr oblems y ou ma y want to pa tch a hot t emp erature in the vicinit y of the an ticipa ted reactions b efore you r estar t the c alcula tion. See Patching Values in S elec ted C ells (p.2607 ) for inf ormation about pa tching an initial v alue f or a flo w variable . 37.21.3. Modifying A lgebr aic M ultigr id P aramet ers The default algebr aic multigr id settings ar e appr opriate for near ly all pr oblems , but in r are cases y ou may need t o mak e minor adjustmen ts.Setting A lgebr aic M ultigr id P aramet ers (p.2589 ) descr ibes ho w to analyz e the multigr id solv er’s performanc e to det ermine which par amet ers. 2693Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Convergenc e and S tabilit y37.21.4. Modifying the M ulti-S tage P aramet ers It is p ossible t o mak e se veral changes t o the multi-stage time-st epping scheme itself . See Changing the M ulti-S tage Scheme (p.2602 ) for detailed inf ormation. 37.21.5. Robustness on M eshes of P oor Q ualit y Poor qualit y meshes ar e meshes c ontaining highly sk ewed c ells, highly non-or thogonal c ells, non- convex cells, or c ells with lef t-handed fac es. Such mesh elemen ts tend t o decr ease the numer ical sta- bilit y of tr aditional CFD discr etiza tion algor ithms .These mesh elemen ts requir e sp ecial tr eatmen t, namely , a numer ical correction of the tr ansp ort equa tion discr etiza tion, which is in tended t o impr ove the numer ical pr operties of the solution algor ithms a t mesh c ells of p oor qualit y. Note If your mesh e xhibits an y type of p oor qualit y except lef t-handed fac es, you c an main tain second or der accur acy by using the w arped-fac e gr adien t correction and disabling p oor mesh numer ics.To disable p oor mesh numer ics, set solve/set/poor-mesh-numer- ics/enable? to no. For additional inf ormation on this metho d, see Warped-F ace Gradien t Correction (p.2697 ). In or der t o facilita te solution c onvergenc e on meshes of p oor qualit y, the ANSY S Fluen t solv er can apply a lo cal solution c orrection, limit ed spa tially t o dist orted c ells of the mesh. If you r ead in a p oor qualit y mesh c ontaining c ells and fac es with c orrupt metr ics, you will see a w arning in the TUI of the form: Info: The mesh contains elements that are invalid or of poor quality. A different numerical scheme will be applied to these elements, which may affect the quality of the solution. It is recommended that you consider removing the invalid and poor quality elements in the mesh. For more information on the invalid and poor quality elements, please use the following TUI commands: /mesh/check /mesh/repair-improve/report-poor-elements. Additionally , in the Solution M etho ds task page , the Rep ort Poor Q ualit y Elemen ts butt on will app ear, which c an b e used t o report mor e sta tistics on the numb er and t ype of c ells tha t ANSY S Fluen t has iden tified as ha ving p oor qualit y (see Figur e 37.50: Reporting P oor Q ualit y Elemen ts (p.2695 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2694Using the S olverFigur e 37.50: Rep orting P oor Q ualit y Elemen ts In or der t o facilita te solution c onvergenc e on meshes of p oor qualit y, the ANSY S Fluen t solv er can apply a lo cal solution c orrection, limit ed spa tially t o dist orted c ells of the mesh. The c orrected solution can b e of 0th, 1st, or 2nd or der: •The 0th or der scheme applies an algor ithm tha t comput es the solution v ariable f or the tr ansp ort equa tion in the bad c ells b y assembling the solution dir ectly fr om the sur rounding solution in the better qualit y cells. •The 1st or der scheme applies lo cally lo w or der discr etiza tion metho ds and neglec ts some non-or tho- gonal c ontributions t o the gr adien ts when c omputing the diffusiv e flux es. •The 2nd or der scheme only mo difies the numer ics in the bad c ells b y assembling the gr adien t vector for the giv en solution v ariable fr om the gr adien ts in the sur rounding b etter qualit y cells. 2695Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Convergenc e and S tabilit yIn other w ords, the discr etiza tion er ror will b e indep enden t of the mesh siz e in this r egion if 0th or der is used . It will decr ease linear ly with subsequen t grid refinemen t when 1st or der is used , and quadr at- ically when the 2nd or der option is selec ted. By default , Fluen t will apply the 1st or der c orrection scheme t o an y invalid c ells. Using t ext commands , you c an fur ther c ontrol the applic ation of the p oor mesh numer ics b y using one of the other schemes , including highly sk ewed and highly non-or thogonal c ells, and including c ells fr om a user-defined r egist er. The t ext commands tha t are available ar e as f ollows: /solve/set/poor-mesh-numerics/enable? Choose whether or not t o apply the p oor mesh numer ics c orrections and sp ecify which or der scheme t o use. In gener al, it is r ecommended tha t you use the 1st or der solution c orrection, which pr ovides a reasonable c ompr omise b etween accur acy and stabilit y gain. For meshes of b etter (and y et still low) qualit y it is ad visable t o try the 2nd or der option, which will pr eser ve the mesh c onvergenc e behavior pr ovided b y the c onvection t erm discr etiza tion schemes . In c ase no c onvergenc e is ob- tained with an y of the af oremen tioned schemes , you should use the 0th or der option, which will provide the highest stabilit y and a t the same time the lo west accur acy. In r egions with highly nonlinear flo w ph ysics this scheme c an yield highly nonph ysical results . The c omputa tional time (or c ost or r un time r equir emen ts) f or all thr ee schemes will incr ease linear ly as the numb er of c ells iden tified as p oor qualit y cells incr eases . Provided tha t ther e is r easonable convergenc e behavior with all thr ee schemes , the 1st or der option will b e the fast est; 0th and 2nd order schemes will ha ve similar r un times t o each other . /solve/set/poor-mesh-numerics/cell-quality-based? Choose whether or not the p oor mesh numer ics should also b e applied t o cells tha t are highly non-or tho- gonal or highly sk ewed. /solve/set/poor-mesh-numerics/set-quality-threshold Set the thr eshold f or including c ells based on c ell qualit y metr ics when cell-quality-based? is enabled .The v alue y ou en ter is applied as a thr eshold f or the c ell or thogonalit y and the c omplemen t of cell sk ewness b elow which the p oor mesh numer ics will b e applied .The default v alue is 0.05 . Some cases ma y requir e tuning this par amet er to impr ove stabilit y. /solve/set/poor-mesh-numerics/user-defined-on-register Answ er yes at the pr ompt t o Include c ells fr om a r egist er in the p oor mesh numer ics tr eatmen t.You will be pr ompt ed f or the name or ID of the r egist er to include . Note tha t if y ou answ er no at the pr ompt an y cells pr eviously included fr om r egist ers ar e remo ved fr om the list of c ells f or p oor mesh numer ics. If you include a user-defined r egist er in the p oor mesh numer ics, reporting of p oor mesh elemen t statistics will also include the c ells added b y the user-defined-on-register command . For example: Poor Mesh Element Statistics: Identified 0 faces with too small area. Identified 0 faces adjacent to negative volume cells. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2696Using the S olverIdentified 0 faces adjacent to bad quality cells. Identified 43 cells from user-defined register. Note The sta tistics not only r eport the c ells included in the r egist er, but also their neighb oring c ells, resulting in an o verall lar ger numb er of c ells b eing iden tified . Imp ortant It is y our r esponsibilit y to main tain the r egist er-based c ells. If you change the mesh, (for e xample , using mesh manipula tion or adapta tion), then y ou must use the user-defined-on-register command again. Enter yes to the c ommand prompt in or der t o up date the c ells based on a new c ell r egist er, other wise , enter no to remo ve all c ells fr om the p oor mesh numer ics list. For mor e inf ormation about c ell r egist ers, see Using C ell R egist ers (p.2758 ). /solve/set/poor-mesh-numerics/print-poor-elements-count Print out a listing of the p oor cells f or each cr iterion (default , cell qualit y, and user-defined). > /solve/set/poor-mesh-numerics/print-poor-elements-count - Number of marked cells based on default criteria = 5 - Number of marked cells based on cell quality criteria = 11 - Number of marked cells based on user-defined criteria = 0 /solve/set/poor-mesh-numerics/reset-poor-elements? Reset the p oor cells included fr om user-defined r egist ers and c ell-qualit y metr ics.The p oor cells iden tified from the in ternal mesh check will b e retained . 37.21.6. Warped-F ace Gradien t Correction The w arped-fac e gr adien t correction ( WFGC) is designed t o impr ove gr adien t accur acy for all gr adien t metho ds—c ell based , node based and least squar es based gr adien ts.WFGC is r ecommended f or 3D simula tions on p olyhedr al, hexahedr al, and h ybrid meshes (meshes c ontaining a mix of he xahedr al and p olyhedr al cells), and it is enabled b y default f or an y mesh tha t contains p olyhedr a. Note tha t these t ypes of mesh c ells ma y not ha ve perfectly planar fac es, which c an aff ect the o verall accur acy of the G reen G auss sur face in tegral.WFGC is also r ecommended when y ou enc oun ter numer ical diffi- culties in simula tions tha t involve a mesh tha t has lar ge diff erences in the v olumes of neighb oring cells, such as he x cells with hanging no de in terfaces. WFGC c omputa tions aim t o resolv e gr adien t accur acy degr adation due t o very high asp ect ratio, cells with non-fla t fac es in the b oundar y layer, and highly def ormed c ells wher e the f ormal c ell c entroid lies outside of the c ontrol volume . WFGC has t wo mo des, fast mo de and memor y sa ving mo de. Fast mo de do es not incr ease gr adien t computa tion time f or sta tic meshes (e xcept f or c ases tha t use the Green-G auss N ode B ased gradien t metho d with a turbulenc e mo del), but it do es requir e additional memor y.There is r oughly a 22% in- crease in memor y for a basic flo w solution, but this additional o verhead do es not change as mor e models (turbulenc e, species tr ansp ort, radia tion, and so on) ar e enabled . Memor y sa ving mo de do es 2697Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Convergenc e and S tabilit ynot incr ease memor y consumption, but it slo ws do wn it eration e xecution time f or sta tic and d ynamic meshes . Imp ortant Enabling Warped-F ace Gradien t Correction through the Solution M etho ds task page enables fast mo de.To swit ch t o memor y sa ving mo de, you must use the TUI c ommand solve/set/warped-face-gradient-correction/enable? and en ter no in r e- sponse t o the use fast mode? prompt. WFGC do es not correct for c ells with lef t-handed fac es. If your mesh c ontains lef t-handed faces, you must use p oor mesh numer ics t o obtain a stable solution. 37.22. Solution S teering For additional inf ormation, see the f ollowing sec tions: 37.22.1. Overview of S olution S teering 37.22.2. Solution S teering S trategy 37.22.3. Using S olution S teering 37.22.1. Overview of S olution S teering Solution st eering in the densit y-based implicit solv er pr ovides y ou with an e xpert system tha t will help naviga te the flo w solution fr om a star ting initial guess t o a c onverged solution with minimum user interaction. When y ou apply solution st eering, you will b e requir ed t o selec t the t ype of flo w tha t best char acterizes the solution domain and the maximum desir ed accur acy, and then allo w the solv er to take the solution t o convergenc e. As the solv er pr oceeds with the solution it eration, certain solv er paramet ers will b e adjust ed b ehind the sc enes t o insur e tha t a c onverged solution t o steady-sta te is possible . Imp ortant Solution st eering is a vailable only f or st eady-sta te flo ws in the densit y-based implicit solv er. 37.22.2. Solution S teering S trategy The c onvergenc e to steady-sta te solution is achie ved in t wo stages .The par amet ers tha t are used in these stages ar e det ermined and set based on user input f or the t ype of flo w tha t can b est char acterize the solution domain. The t ype of flo ws available f or selec tion ar e classified based on flo w compr essib- ility as w ell as the dominan t flo w M ach numb er in the solution domain. The f ollowing flo w types ar e available: •Incompr essible (if the flo w is inc ompr essible , tha t is densit y is c onstan t) •Subsonic (if the flo w is c ompr essible and M<0.75) •Transonic (if the flo w is c ompr essible and 0.651e-06[m^3]) Combined B oolean O peration and C ell R egist er If you w ant to refine c ells near an outlet wher e the pr essur e is less than p0, you c an use an e xpression: AND(Pressure mesh redistribute-boundary-layer face zone id/name [] wall-fluid growth rate [1.1] 1.2 Fluen t will r edistr ibut e the no des in a b oundar y region tha t extends in to the mesh fr om the fac e zone you sp ecify un til one of the f ollowing cr iteria is enc oun tered: •the edge of the domain •a change in z one •a change in elemen t type As with anisotr opic adaption itself , boundar y layer redistr ibution is only a vailable in 3D pr oblems . 38.5. Geometr y-Based A daption This sec tion descr ibes ho w to perform geometr y-based adaption. For mor e inf ormation, see Geometr y- Based A daption in the Theor y Guide . For additional inf ormation, see the f ollowing sec tion: 38.5.1. Performing G eometr y-Based A daption 2723Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Geometr y-Based A daption38.5.1. Performing G eometr y-Based A daption The Geometr y Based A daption D ialog Box (p.3830 ) (Figur e 38.19: The G eometr y Based A daption D ialog Box (p.2724 )) allo ws you t o reconstr uct the geometr y while p erforming b oundar y adaption. Setting U p D omain → Adapt → More → Geometr y... Figur e 38.19: The G eometr y Based A daption D ialo g Box The pr ocedur e for p erforming geometr y-based adaption is as f ollows: 1.Enable the Rec onstr uct Geometr y option. 2.Under Wall Z ones , selec t the z one y ou w ant to adapt and click Set....The Geometr y Based A daption Controls D ialog Box (p.3830 ) will op en. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2724Adapting the M eshFigur e 38.20: The G eometr y Based A daption C ontrols D ialo g Box In the Geometr y Based A daption C ontrols D ialog Box (p.3830 ), set the f ollowing par amet ers: •Specify Levels of P rojec tion P ropaga tion to indic ate the numb er of la yers of the no des y ou w ant to projec t. •Enable Direction of P rojec tion and sp ecify the dir ections in which y ou w ant to pr ojec t the no des. This will mak e the X,Y, and Zfields a vailable . If you w ant no de pr ojec tion in the X dir ection, ent er 1forX. If you do not enable this option, the no de pr ojec tion will tak e plac e at the near est p oint . •(optional) I f you ha ve a fine sur face mesh f or the geometr y, you c an use the Back ground M esh option to load the sur face mesh as a back ground mesh. This will pr ojec t the no des based on the back ground mesh and r econstr uct the geometr y mor e accur ately. •To disable the geometr y reconstr uction f or an y zone in the domain, enable the Disable G eometr y Based A daption f or this Z one option. 3.To disable geometr y-based adaption f or the whole domain, disable Rec onstr uct Geometr y. After setting the par amet ers f or geometr y-based adaption, proceed t o perform mesh adaption. 2725Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Geometr y-Based A daptionRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2726Chapt er 39: Creating S urfaces and C ell Regist ers f or D ispla ying and Rep orting D ata ANSY S Fluen t enables y ou t o selec t portions of the domain t o be used f or visualizing the flo w field .The domain p ortions ar e called surfaces, and ther e ar e man y ways to cr eate them. Sur faces ar e requir ed f or graphic al analy sis of 3D pr oblems b ecause y ou c annot displa y vectors, contours , and so on, or cr eate an X Y plot f or the en tire domain a t onc e. In 2D y ou c an usually visualiz e the flo w field on the en tire domain, but t o cr eate an X Y plot of a v ariable in a p ortion of the in terior of the domain, you must gener ate a sur face. In addition, in b oth 2D and 3D , you will need one or mor e sur faces if y ou w ant to gener ate a sur face-in tegral report. Note tha t ANSY S Fluen t will aut oma tically cr eate a sur face for each boundar y zone in the domain. Sur face inf ormation is st ored in the c ase file . While y ou c an cr eate sur faces to visualiz e portions of the domain, you c an cr eate cell r egist ers t o visu- alize and p erform op erations on c ell gr oupings .You c an gr oup c ells b y: •Region •Boundar y •Variable Limit er •Field Variable •Residuals •Volume •Yplus/Ystar Cell r egist ers ar e sa ved with the c ase file and c an b e used t o displa y mar ked c ells, adapt the mesh, apply poor mesh numer ics, and r eport on the c ells. The f ollowing sec tions e xplain cr eating sur faces and c ell r egist ers: 39.1. Using Sur faces 39.2. Using C ell R egist ers 39.1. Using S urfaces In or der t o visualiz e the in ternal flo w of a 3D pr oblem or cr eate XY plots of solution v ariables f or 3D results , you must selec t portions of the domain (sur faces) on which the da ta is t o be displa yed. Sur faces can also b e used f or visualizing or plotting da ta for 2D pr oblems , and f or gener ating sur face-in tegral reports. ANSY S Fluen t allo ws you t o cr eate se veral kinds of sur faces, and st ores all sur faces in the c ase file .You can cr eate the sur faces thr ough the r ibbon and the outline view and y ou c an r eview and mo dify the existing sur faces in the outline view under the Results branch. These sur faces and their uses ar e descr ibed briefly b elow: 2727Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Zone S urfaces: If you w ant to create a sur face tha t will c ontain the same c ells/fac es as an e xisting c ell/fac e zone , you c an gener ate a z one sur face.This k ind of sur face is useful f or displa ying r esults on b oundar ies. Partition S urfaces: When y ou ar e using the par allel v ersion of ANSY S Fluen t, you ma y find it useful t o create sur faces tha t are defined b y the b oundar ies b etween mesh par titions .You c an then displa y da ta on each side of a par tition boundar y. See Parallel P rocessing (p.3045 ) for mor e inf ormation ab out r unning the par allel solv er. Point Surfaces: To monit or the v alue of some v ariable or func tion a t a par ticular lo cation in the domain, you c an cr eate a surface consisting of a single p oint. Structural P oint Surfaces: To monit or the v alue of some v ariable or func tion a t a p oint in a par ticular c ell of a solid z one in a simula tion tha t uses the str uctural mo del, you c an cr eate a sur face consisting of a single p oint. For example , you c ould monit or the displac emen t of a solid c ell as it mo ves / def orms as par t of a t wo- way intrinsic fluid-str ucture in teraction (FSI) simula tion. Line and R ake Surfaces: To gener ate and displa y pa thlines , you must sp ecify a sur face from which the par ticles ar e released . Line and r ake sur faces ar e well-suit ed f or this pur pose and f or obtaining da ta for compar ison with wind tunnel data. A rake sur face consists of a sp ecified numb er of p oints equally spac ed b etween t wo sp ecified end- points. A line sur face is simply a line tha t includes the sp ecified endp oints and e xtends thr ough the domain; data p oints will b e at the c enters of the c ells thr ough which the line passes , and c onsequen tly will not b e equally spac ed. Plane S urfaces: If you w ant to displa y flo w-field da ta on a sp ecific plane in the domain, you c an cr eate a plane sur face. A plane sur face is simply a plane tha t passes thr ough thr ee sp ecified p oints. Quadr ic Surfaces: To displa y da ta on a line (2D), plane (3D), circle (2D), spher e (3D), or quadr ic sur face you c an sp ecify the surface by en tering the c oefficien ts of the quadr ic func tion tha t defines it. This f eature pr ovides y ou with an e xplicit metho d for defining sur faces. Isosur faces: You c an use an isosur face to displa y results on c ells tha t ha ve a c onstan t value f or a sp ecified v ariable . Gener ating an isosur face based on , , or coordina te, for e xample , will giv e you an , , or cross- section of y our domain. Gener ating an isosur face based on pr essur e will enable y ou t o displa y da ta for another v ariable on a sur face of c onstan t pressur e. Note In some instanc es, newly cr eated sur faces (e xcept z one/line/p oint/rake) ma y contain er roneous lines .This c an happ en f or sur faces cr eated in an y type of c ell z one , but it is mor e lik ely in zones c ontaining p olyhedr al mesh elemen ts. Displa ying a c ontour plot on these sur faces or displa ying the sur faces dir ectly ma y sho w these line edges .To reduc e their app earance you can change the ligh ting metho d to Flat. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2728Creating Sur faces and C ell R egist ers f or D ispla ying and R eporting D ata39.1.1. Zone S urfaces Zone sur faces ar e useful f or displa ying r esults on b oundar ies. For e xample , you ma y want to plot contours of v elocity magnitude a t the inlet and outlet of the pr oblem domain, or t emp erature contours on the domain ’s walls.To do so , you need t o ha ve a sur face tha t contains the same fac es (or c ells) as an e xisting fac e (or c ell) z one . Zone sur faces ar e created aut oma tically f or all b oundar y fac e zones in the domain, so y ou will gener ally not need t o cr eate an y zone sur faces unless y ou acciden tally delet e one . Use the t ext command:surface/reset-zone-surfaces to recreate an y missing sur face zones by resetting the c ase sur face list. To cr eate a z one sur face, you will use the Zone Sur face Dialog Box (p.3962 ) (Figur e 39.1: The Z one Sur face Dialog Box (p.2729 )). Domain → Surface → Create → Zone ... Figur e 39.1: The Z one S urface D ialo g Box The st eps f or cr eating the z one sur face ar e as f ollows: 1. Selec t the z one(s) in the Zone list. 2. Enter a name in New S urface Name if you do not w ant ANSY S Fluen t to assign a default name t o the newly cr eated sur face. By default , Fluen t assigns each sur face the same name as the z one tha t it c orres- ponds t o. If a sur face alr eady exists with tha t name , Fluen t assigns the sur face a unique name using the zone-surface prefix (f or e xample ,zone-surface-6 ). 2729Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using Sur facesIf you do not w ant to use the default name , enter a new name in New S urface Name . If the New Surface Name tha t you en ter is the same as a sur face tha t alr eady exists , Fluen t assigns the new surface a unique name using the zone-surface prefix (f or e xample ,zone-surface-7 ). Imp ortant •The sur face name tha t you en ter must b egin with an alphab etical lett er. If your sur face name b egins with an y other char acter or numb er, Fluen t rejec ts the en try. •If you ar e selec ting multiple z ones , you do not ha ve the option t o cho ose the sur face names . ANSY S Fluen t aut oma tically giv e the sur faces the same names as their c orresponding z one . 3. Click Create.The new sur face name is added t o the Surfaces list in the dialo g box. If you w ant to delet e or other wise manipula te an y sur faces, click Manage ... to op en the Surfaces D ialog Box (p.3933 ). For details , see Grouping , Editing , Renaming , and D eleting Sur faces (p.2755 ). 39.1.2. Partition S urfaces If you ar e using the par allel v ersion of ANSY S Fluen t (see Parallel P rocessing (p.3045 )), you ma y find it useful t o cr eate da ta sur faces defined b y the b oundar ies of mesh par titions . As descr ibed in Mesh Partitioning and L oad B alancing (p.3067 ), par titioning the mesh divides it in to gr oups of c ells tha t can be solv ed on separ ate pr ocessors when y ou use a par allel solv er. A par tition sur face will c ontain fac es or c ells on the b oundar y of t wo mesh par titions . For e xample , you c an plot solution v alues on the partition sur face to det ermine ho w the solution is changing acr oss a par tition in terface, as sho wn in the f ollowing figur e: Figur e 39.2: Contours of C ell P artitions on P artition S urface O verlaid on M esh To cr eate a par tition sur face, you will use the Partition Sur face Dialog Box (p.3885 ) (Figur e 39.3: The Partition Sur face Dialog Box (p.2731 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2730Creating Sur faces and C ell R egist ers f or D ispla ying and R eporting D ata Domain → Surface → Create → Partition... Figur e 39.3: The P artition S urface D ialo g Box The pr ocedur e for cr eating the par tition sur face ar e as f ollows: 1. Specify the par tition b oundar y in which y ou ar e interested b y indic ating the t wo bordering par titions under the Partitions heading .The b oundar y tha t defines the par tition sur face is the b oundar y between the "interior par tition" and the "exterior par tition" .Int Part indic ates the ID numb er of the in terior par tition (tha t is, the par tition under c onsider ation), and Ext Part indic ates the ID numb er of the b ordering (e xter- ior) par tition. The Min and Max fields will indic ate the minimum and maximum ID numb ers of the mesh partitions .The minimum is alw ays zero, and the maximum is one less than the numb er of pr ocessors . If ther e are mor e than t wo mesh par titions , each in terior par tition will shar e boundar ies with se veral exter- ior par titions . By setting the appr opriate values f or Int Part and Ext Part, you c an cr eate sur faces for an y of these b oundar ies. 2. Choose in terior or e xterior fac es or c ells t o be contained in the par tition sur face by selec ting or clear ing Cells and Interior under Options .To obtain a sur face consisting of c ells tha t are on the "interior" side of the par tition b oundar y, selec t both Cells and Interior.To create one c onsisting of c ells tha t are on the "exterior" side , selec t Cells and clear Interior. If you w ant the sur face to contain the fac es on the boundar y inst ead of the c ells, clear the Cells option. To ha ve the fac es reflec t da ta values f or the in terior cells, selec t the Interior check b ox, and t o ha ve them r eflec t values f or the e xterior c ells, clear it. 3. If you do not w ant to use the default name assigned t o the sur face, enter a new name under New S urface Name .The default name is the c oncatenation of the sur face type and an in teger tha t is the new sur face ID (f or e xample ,partition-surface-6 ). (If the New S urface Name you en ter is the same as the 2731Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using Sur facesname of a sur face tha t alr eady exists , ANSY S Fluen t will aut oma tically assign the default name t o the new sur face when it is cr eated.) Imp ortant The sur face name tha t you en ter must b egin with an alphab etical lett er. If the name of the sur face begins with an y other char acter or numb er, ANSY S Fluen t rejec ts the entry. 4. Click Create.The new sur face name is added t o the Surfaces list in the dialo g box. If you w ant to delet e or other wise manipula te an y sur faces, click Manage ... to op en the Surfaces D ialog Box (p.3933 ). For details , see Grouping , Editing , Renaming , and D eleting Sur faces (p.2755 ). 39.1.3. Impr int Surfaces If you w ant to displa y results on sur faces tha t are mor e complic ated than a simple p oint or plane , then you c an imp ort a cust om sur face represen ting the r egion of in terest (.stl or .msh format) and “im- print” this sur face in to the cur rent mesh. For e xample , you ma y want to visualiz e only a smaller cust om portion of a much lar ger (c omple x) geometr y. To cr eate an impr inted sur face, use the Impr int Sur face Dialog Box (p.3835 ) (Figur e 39.4: The Impr int Surface Dialog Box (p.2732 )). Domain → Surface → Create → Impr int... Figur e 39.4: The Impr int Surface D ialo g Box Create an impr inted sur face as f ollows: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2732Creating Sur faces and C ell R egist ers f or D ispla ying and R eporting D ata1. Click Read and selec t your geometr y file (.stl or .msh format) using the Selec t File dialo g box. Specify the units the mesh w as cr eated in (default is met ers). 2. Click OK to upload y our file . The name of y our geometr y file app ears in the Imp orted S urfacedialo g box. 3. Selec t the z one wher e your geometr y is lo cated in the From Z ones group b ox. Note If you do not sp ecify a z one , Fluen t uses the en tire domain f or impr inting . For a lar ge mesh this c ould b e time c onsuming . 4. Enter a name f or y our new sur face in the New S urface Name dialo g box. The default name is (imprint) . 5. Click Create to create the new sur face. When an imp orted sur face is impr inted, a p ostpr ocessing sur face tha t coincides with the imp orted surface is cr eated.The impr inted sur face will not ha ve fac ets f or the p ortions of the or iginal sur face that lie outside the domain. Different postpr ocessing op erations such as c ontour and v ector plots , and surface in tegrals c an b e performed on this sur face. However, the edges of the impr inted sur face ma y not c oincide with those of the or iginal sur face, if the edges of the or iginal sur face do not c oincide with mesh edges . An example is sho wn in the f ollowing pic ture. 2733Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using Sur facesFigur e 39.5: Impr inted S urface (pink) S uperimp osed O ver Imp orted S urface (whit e) As you c an see in Figur e 39.5: Impr inted Sur face (pink) Sup erimp osed O ver Imp orted Sur face (whit e) (p.2734 ), ther e ar e def ormities ar ound the edges of the impr inted sur face. Imp ortant If you w ant to cr eate an impr int sur face from multiple disc onnec ted sour ce sur faces, it is better to cr eate multiple impr int sur faces (one p er sour ce sur face) and , if requir ed, group them t ogether af ter the y are created. For inf ormation on gr ouping sur faces, see Grouping , Editing , Renaming , and D eleting Sur faces (p.2755 ). 39.1.4. Point Surfaces You ma y of ten b e in terested in displa ying r esults a t a single p oint in the domain. For e xample , you may want to monit or the v alue of some v ariable or func tion a t a par ticular lo cation. To do this , you must first cr eate a "point" sur face, which c onsists of a single p oint.When y ou displa y no de-v alue da ta on a p oint sur face, the v alue displa yed is a linear a verage of the neighb oring no de v alues . If you displa y cell-v alue da ta, the v alue a t the c ell in which the p oint lies is displa yed. To cr eate a p oint sur face, use the Point Sur face Dialog Box (p.3898 ) (Figur e 39.6: The P oint Sur face Dialog Box (p.2735 )). Domain → Surface → Create → Point... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2734Creating Sur faces and C ell R egist ers f or D ispla ying and R eporting D ataFigur e 39.6: The P oint Surface D ialo g Box Create a p oint sur face as f ollows: 1. Specify the lo cation of the p oint.There are thr ee diff erent ways to do this: •Enter the c oordina tes (x0, y0, z0) under Coordina tes. •Click Selec t Point With M ouse and then selec t the p oint by click ing on a lo cation in the ac tive graphics windo w with the mouse-pr obe butt on. (See Controlling the M ouse B utton F unctions (p.2833 ) for inf ormation ab out setting mouse butt on func tions .) •Use the Point Tool option t o interactively p osition a p oint in the gr aphics windo w.You c an set the initial lo cation of this p oint using one of the t wo metho ds descr ibed ab ove for sp ecifying the p oint’s position (or y ou c an star t from the p osition defined b y the default Coordina tes). See Using the P oint Tool (p.2736 ) for inf ormation ab out using the p oint tool. 2. If you do not w ant to use the default name assigned t o the sur face, enter a new name under New S urface Name .The default name is the c oncatenation of the sur face type and an in teger tha t is the new sur face ID (f or e xample ,point-5 ). (If the New S urface Name you en ter is the same as the name of a sur face that alr eady exists , ANSY S Fluen t will aut oma tically assign the default name t o the new sur face when it is cr eated.) Imp ortant The sur face name tha t you en ter must b egin with an alphab etical lett er. If the name of the sur face begins with an y other char acter or numb er, ANSY S Fluen t rejec ts the entry. 3. Click Create to create the new sur face. If you w ant to check tha t your new sur face has b een added t o the list of all defined sur faces, or y ou want to delet e or other wise manipula te an y sur faces, click Manage ... to op en the Surfaces D ialog Box (p.3933 ). For details , see Grouping , Editing , Renaming , and D eleting Sur faces (p.2755 ) for details . 2735Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using Sur faces39.1.4.1. Using the P oint Tool The p oint tool enables y ou t o in teractively fine-tune the definition of a p oint using gr aphics . Starting from an initial p oint, you c an tr ansla te the p oint un til its p osition is as desir ed. For e xample , if y ou need t o position a p oint sur face at the c enter of a duc t, just past the inlet , you c an star t with the point tool near the desir ed lo cation (such as on the inlet), and tr ansla te it un til it is in the pr oper plac e. (You ma y find it helpful t o displa y mesh fac es to ensur e tha t the p oint tool is c orrectly p ositioned inside the domain.) 39.1.4.1.1. Initializing the P oint Tool Before enabling the Point Tool option, set the Coordina tes to suitable star ting v alues .You c an enter v alues manually , or use the Selec t Point With M ouse butt on. Often it is c onvenien t to displa y the mesh f or an inlet or isosur face on or near wher e the p oint is t o be lo cated, and then selec t a point on tha t mesh t o sp ecify the initial p osition of the p oint tool. Onc e you ha ve sp ecified the ap- propriate Coordina tes, turn on the t ool b y enabling the Point Tool option. The p oint tool, an eigh t- sided p olygon, will app ear in the gr aphics windo w, as sho wn in Figur e 39.7: The P oint Tool (p.2736 ). Figur e 39.7: The P oint Tool You c an then tr ansla te the p oint tool as descr ibed b elow.The p oint sur face you cr eate will b e lo cated at the c enter of the p oint tool. 39.1.4.1.2. Translating the P oint Tool To transla te the p oint tool in the dir ection along the r ed axis , click the mouse-pr obe butt on (the right butt on b y default) an ywher e on the gr ay par t of the p oint tool and dr ag the mouse un til the tool reaches the desir ed lo cation. Green ar rows will sho w the dir ection of motion. For inf ormation about changing the mouse func tions , see Controlling the M ouse B utton F unctions (p.2833 ). To transla te the t ool in the tr ansv erse dir ections (tha t is, along either of the other ax es), press Shift, click the mouse-pr obe butt on an ywher e on the gr ay par t of the p oint tool, and dr ag the mouse until the t ool reaches the desir ed lo cation. Two sets of gr een ar rows will sho w the p ossible dir ections of motion. In 2D , ther e will b e only one set of gr een ar rows because ther e is only one other dir ection Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2736Creating Sur faces and C ell R egist ers f or D ispla ying and R eporting D atafor tr ansla tion. If you find the p ersp ective distr acting when p erforming this t ype of tr ansla tion, you can tur n it off in the Camer a Paramet ers D ialog Box (p.3695 ) (op ened fr om the Views Dialog Box (p.3690 )), as descr ibed in Controlling P ersp ective and C amer a Paramet ers (p.2842 ). 39.1.4.1.3. Resetting the P oint Tool If you "lose" the p oint tool, or w ant to reset it f or an y other r eason, you c an either click Reset to retur n the p oint tool to the default p osition and star t from ther e, or tur n the t ool off and r e-initializ e it as descr ibed ab ove. In the default p osition, the p oint tool will lie a t the c enter of the domain. 39.1.5. Structural P oint Surfaces You ma y be in terested in r eporting da ta a t a p oint in a par ticular c ell of a solid z one in a simula tion that uses the str uctural mo del. For e xample , you ma y want to monit or the displac emen t of a solid c ell as it mo ves / def orms as par t of a t wo-w ay intrinsic fluid-str ucture in teraction (FSI) simula tion. To do this, you must first cr eate a str uctural "point" sur face, which c onsists of a single p oint.When y ou displa y node-v alue da ta on a str uctural p oint sur face, the v alue displa yed is a linear a verage of the neighb oring node v alues . If you displa y cell-v alue da ta, the v alue a t the c ell in which the p oint lies is displa yed. To cr eate a str uctural p oint sur face, use the Point Sur face Dialog Box (p.3898 ) (Figur e 39.8: The S tructural Point Sur face Dialog Box (p.2737 )). Domain → Surface → Create → Structural P oint... Figur e 39.8: The S tructural P oint Surface D ialo g Box Create a str uctural p oint sur face as f ollows: 1. Specify the lo cation of the p oint.There are thr ee diff erent ways to do this: Note The p oint must b e in a solid c ell z one .The str uctural mo del must also b e enabled f or the Structural P oint Surface dialo g box to be available (r efer to Modeling F luid- Structure In teraction (FSI) Within F luen t (p.2329 ) for additional inf ormation). 2737Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using Sur faces•Enter the c oordina tes (x0, y0, z0) under Coordina tes. •Click Selec t Point With M ouse and then selec t the p oint by click ing on a lo cation in the ac tive graphics windo w with the mouse-pr obe butt on. (See Controlling the M ouse B utton F unctions (p.2833 ) for inf ormation ab out setting mouse butt on func tions .) •Use the Point Tool option t o interactively p osition a p oint in the gr aphics windo w.You c an set the initial lo cation of this p oint using one of the t wo metho ds descr ibed ab ove for sp ecifying the p oint’s position (or y ou c an star t from the p osition defined b y the default Coordina tes). See Using the P oint Tool (p.2736 ) for inf ormation ab out using the p oint tool. 2. If you do not w ant to use the default name assigned t o the sur face, enter a new name under New S urface Name .The default name is the c oncatenation of the sur face type and an in teger tha t is the new sur face ID (f or e xample ,structural-point-5 ). (If the New S urface Name you en ter is the same as the name of a sur face tha t alr eady exists , ANSY S Fluen t will aut oma tically assign the default name t o the new sur face when it is cr eated.) Imp ortant The sur face name tha t you en ter must b egin with an alphab etical lett er. If the name of the sur face begins with an y other char acter or numb er, ANSY S Fluen t rejec ts the entry. 3. Click Create to create the new sur face. If you w ant to check tha t your new sur face has b een added t o the list of all defined sur faces, or y ou want to delet e or other wise manipula te an y sur faces, click Manage ... to op en the Surfaces D ialog Box (p.3933 ). For details , see Grouping , Editing , Renaming , and D eleting Sur faces (p.2755 ) for details . 39.1.6. Line and R ake Surfaces You c an cr eate lines and r akes in the domain f or releasing par ticles , obtaining da ta for c ompar ison with tunnel da ta, and so on. A rake consists of a sp ecified numb er of p oints equally spac ed b etween two sp ecified endp oints. A line is simply a line tha t extends up t o and includes the sp ecified endp oints; data p oints will b e lo cated wher e the line in tersec ts the fac es of the c ell, and c onsequen tly ma y not be equally spac ed. To cr eate a line or r ake sur face, you will use the Line/R ake Sur face Dialog Box (p.3847 ) (Figur e 39.9: The Line/R ake Sur face Dialog Box (p.2739 )). Domain → Surface → Create → Line/R ake... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2738Creating Sur faces and C ell R egist ers f or D ispla ying and R eporting D ataFigur e 39.9: The Line/R ake Surface D ialo g Box The st eps f or cr eating the line or r ake sur face ar e as f ollows: 1. Indic ate whether y ou ar e creating a Line surface or a Rake surface by selec ting the appr opriate item in the Type drop-do wn list. 2. If you ar e creating a r ake sur face, specify the Numb er of P oints to be equally spac ed b etween the t wo endp oints. 3. Specify the lo cation of the line or r ake sur face.There are thr ee diff erent ways to define the lo cation: •Enter the c oordina tes of the first p oint (x0, y0, z0) and the last p oint (x1, y1, z1) under End P oints. •Click Selec t Points With M ouse and then selec t the endp oints by click ing on lo cations in the ac tive graphics windo w with the mouse-pr obe butt on. (See Controlling the M ouse B utton F unctions (p.2833 ) for inf ormation ab out setting mouse butt on func tions .) •Use the Line Tool option t o interactively p osition a line in the gr aphics windo w.You c an set the initial location of this line using one of the t wo metho ds descr ibed ab ove for sp ecifying endp oints (or y ou can star t from the p osition defined b y the default End P oints). See Using the Line Tool (p.2740 ) for in- formation ab out using the line t ool. Note tha t when y ou use the sec ond or thir d metho d descr ibed ab ove, the c oordina tes of the End Points are up dated aut oma tically. 4. If you do not w ant to use the default name assigned t o the sur face, enter a new name under New S urface Name .The default name is the c oncatenation of the sur face type and an in teger tha t is the new sur face ID (f or e xample ,line-5 or rake-6 ). If the New S urface Name you en ter is the same as the name of 2739Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using Sur facesa sur face tha t alr eady exists , ANSY S Fluen t will aut oma tically assign the default name t o the new sur face when it is cr eated. Imp ortant The sur face name tha t you en ter must b egin with an alphab etical lett er. If the name of the sur face begins with an y other char acter or numb er, ANSY S Fluen t rejec ts the entry. 5. Click Create to create the new sur face. If you w ant to check tha t the new sur face has b een added t o the list of all defined sur faces, or y ou want to delet e or other wise manipula te an y sur faces, click Manage ... to op en the Surfaces D ialog Box (p.3933 ). See Grouping , Editing , Renaming , and D eleting Sur faces (p.2755 ) for details . 39.1.6.1. Using the Line Tool The line t ool enables y ou t o in teractively fine-tune the definition of a line or r ake using gr aphics . Starting fr om an initial line , you c an tr ansla te, rotate, and r esize the line un til its p osition, orientation, and length ar e as desir ed. For e xample , if y ou need t o position a r ake sur face just inside the inlet t o a duc t, you c an star t with the line t ool near the desir ed lo cation (such as on the inlet), and tr ansla te, rotate, and r esize it un til you ar e sa tisfied .You ma y find it helpful t o displa y mesh fac es to ensur e that the line t ool is c orrectly p ositioned inside the domain. 39.1.6.1.1. Initializing the Line Tool Before enabling the Line Tool option, set the End P oints to suitable star ting v alues .You c an en ter values manually , or use the Selec t Points With M ouse butt on. Often it is c onvenien t to displa y the mesh f or an inlet or isosur face on or near wher e you w ant to plac e the line or r ake sur face and then selec t two points on tha t mesh t o sp ecify the initial p osition of the line t ool. Onc e you ha ve sp ecified the appr opriate End P oints, enable the Line Tool option. The line t ool app ears in the gr aphics windo w, as sho wn in Figur e 39.10: The Line Tool (p.2741 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2740Creating Sur faces and C ell R egist ers f or D ispla ying and R eporting D ataFigur e 39.10: The Line Tool You c an then tr ansla te, rotate, and/or r esize the line t ool as descr ibed in the f ollowing sec tions . 39.1.6.1.2. Translating the Line Tool To transla te the line t ool in the dir ection along the r ed axis , click the mouse-pr obe butt on (the r ight butt on b y default) an ywher e on the “line” par t of the t ool and dr ag the mouse un til the t ool reaches the desir ed lo cation. Green ar rows will sho w the dir ection of motion F or inf ormation ab out changing the mouse func tions see Controlling the M ouse B utton F unctions (p.2833 ). Imp ortant Do not click the ax es of the line t ool tha t ha ve ar rows on the ends .These ax es c ontrol rotation of the t ool. Click only on the p ortion of the t ool tha t represen ts the pr ospective line sur face.This p ortion is designa ted b y the r ectangles a ttached t o each end . To transla te the t ool in the tr ansv erse dir ections (tha t is, along either of the ax es within the plane perpendicular t o the r ed axis), press Shift, click the mouse-pr obe butt on an ywher e on the "line" par t of the t ool, and dr ag the mouse un til the t ool reaches the desir ed lo cation. Two sets of gr een ar rows will sho w the p ossible dir ections of motion. In 2D , ther e will b e only one set of gr een ar rows because ther e is only one other dir ection f or tr ansla tion. If you find the p ersp ective distr acting when p erform- ing this t ype of tr ansla tion, you c an disable it in the Camer a Paramet ers D ialog Box (p.3695 ) (op ened from the Views Dialog Box (p.3690 )), as descr ibed in Controlling P ersp ective and C amer a Paramet- ers (p.2842 ). 39.1.6.1.3. Rotating the Line Tool To rotate the line t ool, you click the mouse-pr obe butt on on one of the whit e ax es with ar rows. When y ou click one of these ax es, a gr een r ibbon will encir cle the other ar rowed axis , designa ting 2741Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using Sur facesit as the axis of r otation. As you dr ag the mouse along the cir cle t o rotate the t ool, the gr een cir cle will b ecome y ellow. Imp ortant Do not click the r ed axis t o rotate the line t ool. 39.1.6.1.4. Resizing the Line Tool If you plan t o gener ate a r ake sur face, you c an r esize the line t ool to define the length of the r ake. Click the mouse-pr obe butt on in one of the whit e rectangles a t the ends of the "line" par t of the tool (sho wn in black in Figur e 39.10: The Line Tool (p.2741 )) and dr ag the mouse t o lengthen or shor ten the t ool. Green ar rows will sho w the dir ection of str etching/shr inking. 39.1.6.1.5. Resetting the Line Tool If you "lose" the line t ool, or w ant to reset it f or an y other r eason, you c an either click Reset to retur n the line t ool to the default p osition and star t from ther e, or tur n the t ool off and r e-initializ e it as descr ibed ab ove. In the default p osition, the line t ool will lie mid way along the and lengths of the domain, spanning the domain e xtent. 39.1.7. Plane S urfaces To displa y flo w-field da ta on a sp ecific plane in the domain, you will use a plane sur face.You c an create sur faces tha t cut thr ough the solution domain along arbitr ary planes only in 3D; this f eature is not a vailable in 2D . There ar e six t ypes of plane sur faces tha t you c an cr eate: •Intersec tion of the domain with the infinit e plane: This is the default plane sur face created.The e xtents of the plane is det ermined b y the e xtents of the domain. Because the plane is slicing thr ough the domain, the da ta p oints will, by default , be located wher e the plane in tersec ts the fac es of a c ell, and c onsequen tly may not b e equally spac ed. •Bounded plane: This plane will b e a b ounded par allelepip ed, for which 3 of the 4 c orners ar e the 3 p oints that define the plane equa tion (or the 4 c orners ar e the c orners of the "plane t ool"). Like the default plane surface descr ibed ab ove, this t ype of sur face will also ha ve unequally spac ed da ta p oints. •Bounded plane with equally spac ed da ta p oints:This plane is the same as the b ounded plane descr ibed above, except y ou will sp ecify the densit y of p oints along the t wo dir ections of the par allelepip ed, creating a unif orm distr ibution of da ta p oints. •Plane ha ving a c ertain nor mal v ector and passing thr ough a sp ecified p oint:To create this t ype of plane , define a nor mal v ector and a p oint. A plane with the sp ecified nor mal and passing thr ough the sp ecified point will b e created. •Plane aligned with an e xisting sur face:To create this t ype of plane , you will define a single p oint and a surface. A plane par allel t o the selec ted sur face and passing thr ough the sp ecified p oint will b e created. •Plane aligned with the view in the gr aphics windo w:To create this t ype of plane , you will define a single point. A plane par allel t o the cur rent view in the ac tive gr aphics windo w and passing thr ough the sp ecified point will b e created. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2742Creating Sur faces and C ell R egist ers f or D ispla ying and R eporting D ataTo cr eate a plane sur face, you will use the Plane Sur face Dialog Box (p.3895 ) (Figur e 39.11: The P lane Surface Dialog Box (p.2743 )). Domain → Surface → Create → Plane ... Figur e 39.11: The P lane S urface D ialo g Box The pr ocedur e for cr eating the plane sur face is as f ollows: 1. Decide which of the six t ypes of planes y ou w ant to create. •To create the default plane t ype (the in tersec tion of the infinit e plane with the domain), go dir ectly to step 2. •To create a b ounded plane , selec t Bounded under Options . •To create a b ounded plane with equally spac ed da ta p oints, selec t both Bounded and Sample P oints, and then set the numb er of da ta p oints under Sample D ensit y.You will sp ecify the p oint densit y in each dir ection b y en tering the appr opriate values f or Edge 1 and Edge 2 . Edge 1 e xtends fr om p oint 0 to point 1, and edge 2 e xtends fr om p oint 1 t o point 2. •To define a plane aligned with an e xisting sur face, selec t Aligned With S urface, and then cho ose the surface in the Surfaces list and sp ecify a single p oint using one of the first t wo metho ds descr ibed below in st ep 2. 2743Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using Sur faces•To define a plane aligned with the view plane , selec t Aligned With View P lane , and then cho ose a single p oint using one of the first t wo metho ds descr ibed b elow in st ep 2. •To define a plane ha ving a c ertain nor mal v ector and passing thr ough a sp ecified p oint, selec t Point And N ormal , and then sp ecify the nor mal v ector b y en tering v alues in the ix,iy, and iz fields under Normal , and a single p oint using one of the first t wo metho ds descr ibed b elow in st ep 2. 2. Specify the lo cation of the plane sur face.There are thr ee diff erent ways to define the lo cation: •Enter the c oordina tes of the thr ee Points defining the planar sur face: (x0, y0, z0), (x1, y1, z1), and (x2, y2, z2). •Click Selec t Points and then selec t the thr ee p oints by click ing on lo cations in the ac tive gr aphics windo w with the mouse-pr obe butt on. (See Controlling the M ouse B utton F unctions (p.2833 ) for inf orm- ation ab out setting mouse butt on func tions .) •Use the Plane Tool option t o interactively p osition a plane in the gr aphics windo w.You c an set the initial lo cation of this plane using one of the t wo metho ds descr ibed ab ove for sp ecifying the defining points.You c an also star t from the p osition defined b y the default Points. See Using the P lane Tool (p.2744 ) for inf ormation ab out using the plane t ool. Note tha t when y ou use the sec ond or thir d metho d descr ibed ab ove, the c oordina tes of the End Points are up dated aut oma tically. 3. If you do not w ant to use the default name assigned t o the sur face, enter a new name under New S urface Name .The default name is the c oncatenation of the sur face type and an in teger tha t is the new sur face ID (f or e xample ,plane-7 ). (If the New S urface Name you en ter is the same as the name of a sur face that alr eady exists , ANSY S Fluen t will aut oma tically assign the default name t o the new sur face when it is cr eated.) Imp ortant The sur face name tha t you en ter must b egin with an alphab etical lett er. If the name of the sur face begins with an y other char acter or numb er, ANSY S Fluen t rejec ts the entry. 4. Click Create to create the new sur face. If you w ant to check tha t your new sur face has b een added t o the list of all defined sur faces, or y ou want to delet e or other wise manipula te an y sur faces, click Manage ... to op en the Surfaces D ialog Box (p.3933 ). See Grouping , Editing , Renaming , and D eleting Sur faces (p.2755 ) for details . 39.1.7.1. Using the P lane Tool The plane t ool enables y ou t o in teractively fine-tune the definition of a plane using gr aphics . Starting from an initial plane , you c an tr ansla te, rotate, and r esize the plane un til its p osition, orientation, and size ar e as desir ed. For e xample , if y ou need t o position a plane sur face at a cr oss-sec tion of an ir reg- ular ly-shap ed, cur ved duc t, you c an star t with the plane t ool near the desir ed lo cation, resize it, transla te it un til it is within the duc t walls, and r otate it t o the pr oper or ientation. You ma y find it helpful t o displa y mesh fac es to ensur e tha t the plane t ool is c orrectly p ositioned inside the domain. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2744Creating Sur faces and C ell R egist ers f or D ispla ying and R eporting D ata39.1.7.1.1. Initializing the P lane Tool Before enabling the Plane Tool option, set the Points to suitable star ting v alues .You c an en ter values manually , or use the Selec t Points butt on. Often it is c onvenien t to displa y the mesh f or an inlet or isosur face tha t is similar t o the desir ed plane sur face, and then selec t thr ee p oints on tha t mesh t o position the initial plane . Onc e you ha ve sp ecified the appr opriate Points, enable the Plane Tool option. The plane t ool will app ear in the gr aphics windo w, as sho wn in Figur e 39.12: The P lane Tool (p.2745 ). Figur e 39.12: The P lane Tool You c an then tr ansla te, rotate, and/or r esize the plane t ool as descr ibed in the f ollowing sec tions . 39.1.7.1.2. Translating the P lane Tool To transla te the plane t ool in the dir ection nor mal t o the plane , click the mouse-pr obe butt on (the right butt on b y default) an ywher e on the gr ay par t of the plane t ool and dr ag the mouse un til the tool reaches the desir ed lo cation. Green ar rows will sho w the dir ection of motion. For inf ormation about changing the mouse func tions see Controlling the M ouse B utton F unctions (p.2833 ). To transla te the t ool in the tr ansv erse dir ections (tha t is, along either of the ax es tha t lie within the plane), press Shift, click the mouse-pr obe butt on an ywher e on the gr ay par t of the plane t ool, and drag the mouse un til the t ool reaches the desir ed lo cation. Two sets of gr een ar rows will sho w the possible dir ections of motion. If you find the p ersp ective distr acting when p erforming this t ype of transla tion, you c an tur n it off in the Camer a Paramet ers D ialog Box (p.3695 ) (op ened fr om the Views Dialog Box (p.3690 )), as descr ibed in Controlling P ersp ective and C amer a Paramet ers (p.2842 ). 39.1.7.1.3. Rotating the P lane Tool To rotate the plane t ool, click the mouse-pr obe butt on on one of the whit e ar rows at the tips of the plane ’s ax es. Clicking on an y ar row rotates the t ool ab out either of the other t wo ax es: when y ou click the ar row, two gr een r ibbons will encir cle the plane t ool, forming cir cles ab out each of the t wo possible ax es of r otation. Drag the mouse along the desir ed cir cle t o rotate the t ool. As you do so , the cir cle along which the t ool is r otating will b ecome y ellow. 2745Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using Sur facesThe f ollowing not es ma y help y ou when y ou ar e rotating the plane t ool: •Onc e you mo ve your mouse along one cir cle, you c annot change the dir ection of r otation unless y ou release the mouse-pr obe butt on and tr y again. Be careful t o star t mo ving y our mouse v ery steadily so that you c an cho ose the c orrect dir ection. •Do not click the r ed ar row to rotate. •Do not tr y to rotate by click ing on an ar row tha t is p ointing a way from y ou. It will b e very difficult f or you t o judge which dir ection of r otation is c orrect from this p oint of view . Because ther e are two ar rows on each axis , ther e will alw ays be an appr opriate arrow available . •Do not r otate the plane t ool mor e than 90° or so a t onc e. If you r otate the t ool b y a lar ge angle , the ar row on which y ou ar e click ing will b egin t o point away from y ou, and y ou will ha ve trouble c ontrolling the rotation (as discussed in the it em ab ove). 39.1.7.1.4. Resizing the P lane Tool If you plan t o gener ate a b ounded plane , you c an r esize the plane t ool to define the plane ’s boundar ies. Click the mouse-pr obe butt on in one of the whit e squar es a t the plane t ool’s corners (sho wn in black in Figur e 39.12: The P lane Tool (p.2745 )) and dr ag the mouse t o str etch or shr ink the tool. Green ar rows will sho w the dir ection of the plane ’s diagonal. Imp ortant Be careful not t o dr ag y our mouse acr oss an y of the ax es while r esizing the t ool.This will flip the t ool o ver and c orrupt it. If you acciden tally do this , reset the plane t ool and star t again. 39.1.7.1.5. Resetting the P lane Tool If you "lose" the plane t ool, or w ant to reset it f or an y other r eason, you c an either click Reset P oints to retur n the plane t ool to the default p osition and star t from ther e, or tur n the t ool off and r e-ini- tializ e it as descr ibed ab ove. In the default p osition, the plane t ool will lie mid way along the length of the domain, spanning the and domain e xtents. 39.1.8. Quadr ic Surfaces If you w ant to displa y da ta on a line (2D), plane (3D), circle (2D), spher e (3D), or gener al quadr ic sur face, you c an sp ecify the sur face by en tering the c oefficien ts of the quadr ic func tion tha t defines it. This feature pr ovides y ou with an e xplicit metho d for defining sur faces. See Line and R ake Sur faces (p.2738 ) and Plane Sur faces (p.2742 ) for additional metho ds for cr eating line and plane sur faces. To cr eate a quadr ic sur face, you will use the Quadr ic Sur face Dialog Box (p.3899 ) (Figur e 39.13: The Quadr ic Sur face Dialog Box (p.2747 )). Domain → Surface → Create → Quadr ic... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2746Creating Sur faces and C ell R egist ers f or D ispla ying and R eporting D ataFigur e 39.13: The Q uadr ic S urface D ialo g Box The st eps f or cr eating the quadr ic sur face ar e as f ollows: 1. Decide which t ype of quadr ic sur face you w ant to create. In 3D , cho ose Plane ,Spher e, or (gener al) Quadr ic in the Type drop-do wn list. In 2D , cho ose Line ,Circle, or Quadr ic. 2. Specify the defining equa tion f or the sur face in SI units . •Line or plane sur face: If you ha ve selec ted Line (in 2D) or Plane (in 3D) as the sur face type, the sur face will c onsist of all p oints on the domain tha t satisfy the equa tion .You will specify ix (the c oefficien t of ),iy (the c oefficien t of ),iz (the c oefficien t of ), and distanc e (the distanc e of the line or plane fr om the or igin) in the fields t o the r ight of the Type drop-do wn list. When you click Update under the Quadr ic Func tion heading , the displa y of the quadr ic func tion c oefficien ts will change t o reflec t your inputs . •Circle or spher e sur face: If you ha ve selec ted Circle (in 2D) or Spher e (in 3D) as the sur face type, the surface will c onsist of all p oints on the domain tha t satisfy the equa tion . You will sp ecify x0,y0,z0 (the , , and coordina tes of the spher e or cir cle’s center) and r (the r adius) in the fields t o the r ight of the Type drop-do wn list. When y ou click Update under the Quadr ic Func tion heading , the displa y of the quadr ic func tion c oefficien ts will change t o reflec t your inputs . •Quadr ic sur face: If you ha ve selec ted Quadr ic as the sur face type, the sur face will c onsist of all p oints in the domain tha t satisfy the gener al quadr ic func tion .You will sp ecify the c oefficien ts of the quadr ic func tion (the c oefficien ts of the t erms , , , xy, yz, zx, x, y, z and the c onstan t term) directly in the Quadr ic Func tion box, and y ou will set value to the r ight of the Type drop-do wn list. Note tha t the Update butt on will b e disabled when y ou cho ose this t ype of sur face. 3. If you do not w ant to use the default name assigned t o the sur face, enter a new name under New S urface Name .The default name is the c oncatenation of the sur face type and an in teger tha t is the new sur face ID (f or e xample ,sphere-slice-7 or quadric-slice-10 ). If the New S urface Name you en ter is 2747Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using Sur facesthe same as the name of a sur face tha t alr eady exists , ANSY S Fluen t will aut oma tically assign the default name t o the new sur face when it is cr eated. Imp ortant The sur face name tha t you en ter must b egin with an alphab etical lett er. If the name of the sur face begins with an y other char acter or numb er, ANSY S Fluen t rejec ts the entry. 4. Click Create to create the new sur face. If you w ant to check tha t your new sur face has b een added t o the list of all defined sur faces, or y ou want to delet e or other wise manipula te an y sur faces, click Manage ... to op en the Surfaces D ialog Box (p.3933 ). See Grouping , Editing , Renaming , and D eleting Sur faces (p.2755 ) for details . 39.1.9. Isosur faces If you w ant to displa y results on c ells tha t ha ve a c onstan t value f or a sp ecified v ariable , you will need to cr eate an isosur face of tha t variable . Gener ating an isosur face based on , , or coordina te, for example , will giv e you an , , or cross-sec tion of y our domain; gener ating an isosur face based on pressur e will enable y ou t o displa y da ta for another v ariable on a sur face of c onstan t pressur e.You can cr eate an isosur face from an e xisting sur face or fr om the en tire domain. Further mor e, you c an r estrict any isosur face to a sp ecified c ell z one . Imp ortant Note tha t you c annot cr eate an isosur face un til you ha ve initializ ed the solution, performed calcula tions , or r ead a da ta file . To cr eate an isosur face, you will use the Iso-Sur face Dialog Box (p.3842 ) (Figur e 39.14: The I so-Sur face Dialog Box (p.2749 )). Domain → Surface → Create → Iso-S urface... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2748Creating Sur faces and C ell R egist ers f or D ispla ying and R eporting D ataFigur e 39.14: The I so-S urface D ialo g Box The st eps f or cr eating the isosur face ar e as f ollows: 1. Choose the sc alar v ariable t o be used f or isosur facing in the Surface of C onstan t drop-do wn list. First, selec t the desir ed c ategor y in the upp er list. You c an then selec t from r elated quan tities fr om the lo wer list. (See Field F unction D efinitions (p.2959 ) for an e xplana tion of the v ariables in the list.) 2. If you w ant to create an isosur face from an e xisting sur face (tha t is, gener ate a new sur face of c onstan t , , temp erature, pressur e, and so on tha t is a subset of another sur face), cho ose tha t sur face in the From S urface list. You c an sp ecify the c ell z one on which y ou w ant to create an isosur face by selec ting the z one in the From Z ones list. •If you do not selec t a sur face from the list , the isosur facing will b e performed on the en tire domain. •If you do not selec t a z one fr om the list , then the isosur facing will not b e restricted t o an y cell z one and will r un thr ough the en tire domain. 3. Click Comput e to calcula te the minimum and maximum v alues of the selec ted sc alar field in the domain or on the selec ted sur face (in the From S urface list). The minimum and maximum v alues will b e displa yed in the Min and Max fields . 4. Set the iso value using one of the f ollowing metho ds. (Note tha t the sec ond metho d will enable y ou t o define multiple iso values in a single isosur face.) 2749Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using Sur faces•You c an set an iso value in teractively b y mo ving the slider with the lef t mouse butt on.The v alue in the Iso-V alues field will b e up dated aut oma tically.This metho d will also cr eate a t emp orary isosur face in the gr aphics windo w. Using the slider enables y ou t o pr eview an isosur face before creating it. Imp ortant Even though the isosur face is displa yed, it is only a t emp orary sur face.To cr eate an isosur face, use the Create butt on af ter deciding on a par ticular iso value . •You c an t ype in iso values in the Iso-V alues field dir ectly, separ ating multiple v alues b y whit e spac e. Multiple iso values will b e contained in a single isosur face; tha t is, you c annot selec t subsur faces within the r esulting isosur face. 5. If you do not w ant to use the default name assigned t o the sur face, enter a new name under New S urface Name .The default name is the c oncatenation of the sur face type and an in teger tha t is the new sur face ID (f or e xample ,z-coordinate-6 ). (If the New S urface Name you en ter is the same as the name of a sur face tha t alr eady exists , ANSY S Fluen t will aut oma tically assign the default name t o the new sur face when it is cr eated.) Imp ortant The sur face name tha t you en ter must b egin with an alphab etical lett er. If the name of the sur face begins with an y other char acter or numb er, ANSY S Fluen t rejec ts the entry. 6. Click Create.The new sur face name will b e added t o the From S urface list in the dialo g box. If you w ant to delet e or other wise manipula te an y sur faces, click Manage ... to op en the Surfaces D ialog Box (p.3933 ). See Grouping , Editing , Renaming , and D eleting Sur faces (p.2755 ) for details . 39.1.10. Clipping S urfaces If you ha ve created a sur face, but y ou do not w ant to use the whole sur face to displa y da ta, you c an clip the sur face between t wo iso values t o cr eate a new sur face tha t spans a sp ecified subr ange of a specified sc alar quan tity.The clipp ed sur face consists of those p oints on the selec ted sur face wher e the sc alar field v alues ar e within the sp ecified r ange . For e xample , in Figur e 39.15: External Wall Sur face Isoclipp ed t o Values of x C oordina te (p.2751 ) the e xternal w all has b een clipp ed t o values of coordina te less than 0 t o sho w only the back half of the w all, enabling y ou t o see the v alve inside the in take port. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2750Creating Sur faces and C ell R egist ers f or D ispla ying and R eporting D ataFigur e 39.15: External Wall S urface Isoclipp ed t o Values of x C oordina te To clip an e xisting sur face, you will use the Iso-C lip D ialog Box (p.3841 ) (Figur e 39.16: The I so-C lip D ialog Box (p.2752 )). Domain → Surface → Create → Iso-C lip... 2751Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using Sur facesFigur e 39.16: The I so-C lip D ialo g Box The st eps f or clipping a sur face ar e as f ollows: 1.Choose the sc alar v ariable on which the clipping will b e based in the Clip To Values O f drop-do wn list. First, selec t the desir ed c ategor y in the upp er list. You c an then selec t from r elated quan tities fr om the lower list. See Field F unction D efinitions (p.2959 ) for an e xplana tion of the v ariables in the list. 2.Selec t the sur face to be clipp ed in the Clip S urface list. 3.Click Comput e to calcula te the minimum and maximum v alues of the selec ted sc alar field on the selec ted surface.The minimum and maximum v alues ar e displa yed in the Min and Max fields . 4.Define the clipping r ange using one of the f ollowing metho ds. •You c an set the upp er and lo wer limits of the clipping r ange in teractively b y mo ving the indic ator in each dial (tha t is, the dial ab ove the Min or Max field) with the lef t mouse butt on.The v alue in the corresponding Min or Max field is up dated aut oma tically.This metho d will also cr eate a t emp orary surface in the gr aphics windo w. Using the dials enables y ou t o pr eview a clipp ed sur face before creating it. Imp ortant Even though the clipp ed sur face is displa yed, it is only a t emp orary sur face.To cr eate the new sur face, use the Clip butt on af ter deciding on the clipping r ange . •You c an t ype the minimum and maximum v alues in the clipping r ange dir ectly in the Min and Max fields . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2752Creating Sur faces and C ell R egist ers f or D ispla ying and R eporting D ata5.If you do not w ant to use the default name assigned t o the sur face, enter a new name under New S urface Name .The default name is the c oncatenation of the sur face type and an in teger tha t is the new sur face ID (f or e xample ,clip-density-8 ). (If the New S urface Name you en ter is the same as the name of a surface tha t alr eady exists , ANSY S Fluen t will aut oma tically assign the default name t o the new sur face when it is cr eated.) Imp ortant The sur face name tha t you en ter must b egin with an alphab etical lett er. If the name of the sur face begins with an y other char acter or numb er, ANSY S Fluen t rejec ts the en try. 6.Click Clip.The new sur face name is added t o the Clip S urface list in the dialo g box. (The or iginal sur face will r emain unchanged .) If you w ant to delet e or other wise manipula te an y sur faces, click Manage ... to op en the Surfaces D ialog Box (p.3933 ). See Grouping , Editing , Renaming , and D eleting Sur faces (p.2755 ) for details . 39.1.11. Transf orming S urfaces You c an cr eate a new da ta sur face from an e xisting sur face by rotating and/or tr ansla ting the or iginal surface. For e xample , you c an r otate the sur face of a c omplic ated turb omachiner y blade t o plot da ta in the r egion b etween blades .You c an also cr eate a new sur face at a c onstan t nor mal distanc e from the or iginal sur face. To transf orm an e xisting sur face to cr eate a new one , you will use the Transf orm Sur face Dialog Box (p.3935 ) (Figur e 39.17: The Transf orm Sur face Dialog Box (p.2754 )). Domain → Surface → Create → Transf orm... 2753Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using Sur facesFigur e 39.17: The Transf orm S urface D ialo g Box The st eps f or tr ansf orming a sur face ar e as f ollows: 1.Selec t the sur face to be transf ormed in the Transf orm S urface list. Imp ortant The tr ansf orm op eration is not a vailable f or user-cr eated sur faces such as lines , points, iso-sur faces, and so on. To cr eate a tr ansf ormed line , point, iso-sur face, or other user- created sur face, you must manually tr ansla te the input p oint(s) and cr eate a new line/p oint/iso-sur face in the r espective dialo g box (Line/R ake,Point Surface,Iso-S urface, and so on). 2.Set the appr opriate transf ormation par amet ers, as descr ibed b elow.You c an p erform an y combina tion of tr ansla tion, rotation, and “isodistancing ” on the sur face. •Rotation: To rotate a sur face, specify the or igin ab out which the sur face is r otated, and the angle b y which the sur face is r otated. In the About box under Rota te, specify a p oint, and the or igin of the c oordina te sy stem f or the rotation will b e set t o tha t point. (The , , and directions will b e the same as f or the global coordina te sy stem.) F or e xample , if y ou sp ecified the p oint (1,5,3) in 3D , rotation w ould b e ab out the , , and axes anchor ed a t (1,5,3). You c an either en ter the p oint’s coordina tes in the x, y, and z fields or click Mouse S elec t and selec t a p oint in the gr aphics windo w using the mouse- probe butt on. See Controlling the M ouse B utton F unctions (p.2833 ) for inf ormation ab out mouse butt on func tions . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2754Creating Sur faces and C ell R egist ers f or D ispla ying and R eporting D ataIn the Angles box under Rota te, specify the angles ab out the , , and axes (tha t is, the ax es of the c oordina te sy stem with the or igin defined under About) by which the sur face is r otated. For 2D pr oblems , you c an sp ecify r otation ab out the axis only . •Transla tion: To transla te a sur face, define the distanc e by which the sur face is tr ansla ted in each dir ection. Set the x,y, and z transla tion distanc es under Transla te. •Isodistancing: To create a sur face positioned a t a c onstan t nor mal distanc e around the or iginal sur face, set the v alue f or d under Iso-D istanc e. 3.If you do not w ant to use the default name assigned t o the sur face, enter a new name under New S urface Name .The default name is the c oncatenation of the sur face type and an in teger tha t is the new sur face ID (f or e xample ,transform-9 ). If the New S urface Name you en ter is the same as the name of a sur face that alr eady exists , ANSY S Fluen t will aut oma tically assign the default name t o the new sur face when it is cr eated. Imp ortant The sur face name tha t you en ter must b egin with an alphab etical lett er. If the name of the sur face begins with an y other char acter or numb er, ANSY S Fluen t rejec ts the en try. 4.Click Create.The new sur face name is added t o the Transf orm S urface list in the dialo g box.The or iginal surface will r emain unchanged . If you w ant to delet e or other wise manipula te an y sur faces, click Manage ... to op en the Surfaces D ialog Box (p.3933 ). See Grouping , Editing , Renaming , and D eleting Sur faces (p.2755 ) for details . 39.1.12. Grouping , Editing , Renaming , and D eleting S urfaces Onc e you ha ve created a numb er of sur faces, you c an edit , rename , delet e, and gr oup sur faces and obtain inf ormation ab out their c omp onen ts. Grouping sur faces is useful if y ou w ant to perform p ost- processing on a numb er of sur faces a t a time . For e xample , you ma y want to gr oup se veral w all sur faces together t o gener ate a c ontour plot of t emp erature on all w alls.To postpr ocess r esults on each w all surface individually ,“ungr oup ” the sur faces. You c an manipula te existing sur faces and cr eate new ones thr ough the Surfaces branch of the Outline View. Results → Surfaces 2755Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using Sur facesAdditionally , you c an manipula te existing sur faces within the Surfaces D ialog Box (p.3933 ) (Fig- ure 39.18: The Sur faces D ialog Box (p.2756 )). Domain → Surface → Manage ... Figur e 39.18: The S urfaces D ialo g Box You c an also op en this dialo g box by click ing Manage ... in one of the sur face creation dialo g boxes descr ibed in the pr evious sec tions or b y double-click ing the Surfaces branch in the Outline View. For additional inf ormation, see the f ollowing sec tions: 39.1.12.1. Grouping Sur faces 39.1.12.2. Editing and R enaming Sur faces 39.1.12.3. Deleting Sur faces 39.1.12.4. Sur face Statistics Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2756Creating Sur faces and C ell R egist ers f or D ispla ying and R eporting D ata39.1.12.1. Grouping S urfaces As men tioned ab ove, you ma y want to gr oup se veral sur faces together in or der t o perform p ostpr o- cessing on all of them a t onc e.To cr eate a sur face gr oup , selec t the sur faces to be gr oup ed in the Surfaces list. You c an define a new name f or the gr oup in the Name field , or y ou c an use the default name , which is the name of the first sur face you selec ted in the Surfaces list. Then click Group .The selec ted sur faces disapp ear fr om the Surfaces list, and the name of the sur face gr oup is added t o the list. Imp ortant The Group butt on will not app ear un til you ha ve selec ted a t least t wo sur faces. As so on as y ou cho ose a sec ond sur face in the Surfaces list, the Rename butt on will change t o the Group butt on. To ungr oup the sur faces, simply selec t the sur face gr oup in the Surfaces list and click UnGroup .The group name will disapp ear fr om the list and the names of the or iginal sur faces in the gr oup will r e- app ear in the list. 39.1.12.2. Editing and R enaming S urfaces You c an edit sur faces either b y double-click ing the sur face in the Surfaces branch of the Outline View or b y right-click ing it and selec ting Edit....This op ens the r esp ective sur face dialo g box wher e you can mo dify settings and r ename the sur face. Results → Surfaces → Edit... To change the name of an e xisting sur face, selec t the sur face in the Surfaces list of the Surfaces dialo g box, enter a new name in the Name field , and then click Rename .The new name r eplac es the old name in the Surfaces list and the sur face is other wise unchanged . If you selec t mor e than one sur face, the Rename butt on will not app ear in the dialo g box.When mor e than one sur face is selec ted, the Rename butt on is r eplac ed b y the Group butt on. Imp ortant The sur face name tha t you en ter must b egin with an alphab etical lett er. If the name of the sur face begins with an y other char acter or numb er, ANSY S Fluen t rejec ts the en try. 2757Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using Sur faces39.1.12.3. Deleting S urfaces If you find tha t a sur face is no longer useful, you ma y want to delet e it t o pr event the list of sur faces from b ecoming t oo clutt ered. Selec t the sur face or sur faces to be delet ed in the Surfaces list, and then click Delet e.The delet e op eration is not r eversible , so if y ou w ant to get a delet ed sur face back again y ou will need t o recreate it using one of the sur face-cr eation dialo g boxes descr ibed in the previous sec tions . 39.1.12.4. Surface Statistics You c an also use the Surfaces D ialog Box (p.3933 ) to retrieve topological inf ormation ab out sur faces. Points is the t otal numb er of no des in a sur face.0D F acets is the numb er of isola ted no des in a surface (tha t is, nodes tha t ha ve no c onnec tivit y, such as p oint sur faces or no des in a r ake),1D F acets is the numb er of linear fac es (c onsisting of t wo connec ted no des) in a sur face in a 2D pr oblem, and 2D F acets is the numb er of 2D fac es (tr iangular or quadr ilateral) in a sur face in a 3D pr oblem. Note that an interior zone sur face in a 3D pr oblem c onsists of 2D fac ets, and similar ly an interior zone surface in a 2D pr oblem c onsists of 1D fac ets. These sta tistics ar e list ed f or the sur face(s) selec ted in the Surfaces list. If mor e than one sur face is selec ted, the sum o ver all selec ted sur faces is displa yed f or each quan tity. Note tha t if y ou w ant to check these sta tistics f or a sur face tha t was read fr om a c ase file , you will need t o first displa y it. 39.2. Using C ell Regist ers Cell r egist ers ar e a means f or mar king c ells based on c ertain cr iteria, such as iso-v alues or pr oximit y to a boundar y.You c an then use these mar ked c ell r egist ers t o perform op erations lik e refining or coarsening the mesh ( Adapting the M esh (p.2705 )) or pa tching the solution ( Patching Values in S elec ted Cells (p.2607 )). The f ollowing sec tions descr ibe ho w to cr eate and use c ell r egist ers: 39.2.1. Region 39.2.2. Boundar y 39.2.3. Variable Limit er 39.2.4. Field Variable 39.2.5. Residuals 39.2.6. Volume 39.2.7. Yplus/Ystar 39.2.8. Manage C ell R egist ers 39.2.9. Cell R egist er Op erations 39.2.10. Copying and R enaming C ell R egist ers Note •If you ha ve multiple c ell regist ers tha t you w ant to displa y within the same gr aphics windo w, you c an enable the Overlays option in the Scene D escr iption dialo g box (acc essed b y click ing Comp ose ... in the View ribbon tab). With this option enabled , each subsequen t cell regist er you displa y is sho wn on t op of the e xisting gr aphics windo w displa y. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2758Creating Sur faces and C ell R egist ers f or D ispla ying and R eporting D ata•(Parallel only) The e xact numb er of c ells in a r egist er ma y vary between sessions r unning on dif- ferent core coun ts for the same c ase. However, any cell c oun t variations ar e not t o a degr ee tha t they could impac t the r esults . 39.2.1. Region Region r egist ers allo w you t o mar k cells inside or outside of a giv en r egion tha t you c an sp ecify using text or mouse inputs . Using t ext input , you c an sp ecify the r egion as a he xahedr on (quadr ilateral in 2D), a spher e (cir cle in 2D), or a c ylinder . 39.2.1.1. Defining a R egion The basic appr oach t o cr eating a r egion c ell r egist er is t o first define a r egion: •The he xahedr on (quadr ilateral) is defined b y en tering the c oordina tes of t wo points defining the diagonal. •The spher e (cir cle) is defined b y en tering the c oordina tes of the c enter of the spher e and its r adius . •To define a c ylinder , specify the c oordina tes of the p oints defining the c ylinder axis , and the r adius . In 3D this will define a c ylinder . In 2D , you will ha ve an arbitr arily or iented r ectangle with length equal t o the cylinder axis length and width equal t o the r adius . A rectangle defined using the c ylinder option diff ers fr om one defined with the quadr ilateral option in tha t the f ormer c an b e arbitr arily or iented in the domain, while the la tter must b e aligned with the c oordina te ax es. You c an either en ter the e xact coordina tes in to the appr opriate real en try fields or selec t the lo cations with the mouse on displa ys of the mesh or solution field . After the r egion is defined , each c ell tha t has a c entroid inside/outside the sp ecified r egion is mar ked. 39.2.1.2. Setting Up a R egion C ell R egist er To cr eate a r egion c ell r egist er: 1.Open the Figur e 39.19: Region R egist er D ialog Box (p.2760 ). Solution → Cell Regist ers New → Region... 2759Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using C ell R egist ersFigur e 39.19: Region Regist er D ialo g Box 2.Specify whether the r egist er includes c ells Inside or Outside of the defined r egion. •If you cho ose Inside , cells with c entroids within the sp ecified r egion will b e mar ked. •If you cho ose Outside , cells with c entroids outside the sp ecified r egion will b e mar ked. 3.Choose the shap e for the r egion r egist er. In 2D , you ma y sp ecify a Quad (tha t is, a quadr ilateral),Circle, or Cylinder by mak ing a selec tion from the Shap es group b ox. In 3D , your options include Hex (tha t is, a he xahedr on), Spher e, or Cylinder . 4.Define the r egion b y en tering v alues in to the dialo g box or b y using the mouse . In the dialo g box, the inputs ar e as f ollows: •To define a he xahedr on or quadr ilateral, enter the c oordina tes of t wo points defining the diagonal of the b ox. For a he xahedr on, define X M in,Y M in, and Z M in, as w ell as X M ax,Y M ax, and Z M ax. For a quadr ilateral, define X M in and Y M in, as w ell as X M ax and Y M ax. •To define a spher e or cir cle, enter the v alues f or the Radius and the c oordina tes of its c enter:X Center, Y Center, and Z Center for a spher e, or X Center and Y Center for a cir cle. •To define a c ylinder , enter the v alue f or the Radius and the minimum and maximum c oordina tes de- fining the c ylinder axis: X-A xis M in,Y-A xis M in, and Z-A xis M in, as w ell as X-A xis M ax,Y-A xis M ax, and Z-A xis M ax for 3D , or X-A xis M in and Y-A xis M in, as w ell as X-A xis M ax and Y-A xis M ax for 2D . In 2D , this will b e the width of the r esulting r ectangle . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2760Creating Sur faces and C ell R egist ers f or D ispla ying and R eporting D ataTo define the r egion using the mouse , click the Selec t Points with M ouse butt on. Using the r ight mouse butt on, selec t the input c oordina tes fr om a displa y of the mesh or solution field . After se- lecting the p oints, the v alues will b e loaded aut oma tically in to the appr opriate fields in the dialo g box. See Controlling the M ouse B utton F unctions (p.2833 ) for details ab out mouse butt on func tions . You ha ve the option of editing these v alues b efore mark ing . •To define a he xahedr on or quadr ilateral, selec t the t wo points of the diagonal in an y or der. •To define a spher e or cir cle, first selec t the lo cation of the c entroid and then selec t a p oint tha t lies on the spher e/cir cle (tha t is, a point tha t is one r adius a way from the c entroid). •To define a c ylinder , first selec t the t wo points tha t define the c ylinder axis and then selec t a p oint that is one r adius a way from the axis . 5.Click Save to create the c ell regist er. Note You c an change the w ay the r egist er is displa yed b y using the Cell R egist er D ispla y Options D ialog Box (p.3788 ) dialo g box tha t op ens b y click ing Displa y Options .... 39.2.2. Boundar y Boundar y regist ers allo w you t o mar k cells within the pr oximit y of a b oundar y.The pr oximit y to the boundar y can b e based on: •cell distanc e—the distanc e of a c ell fr om the b oundar y is measur ed b y the numb er of c ells. •normal distanc e—the distanc e is based on the nor mal distanc e of a c ell fr om the b oundar y (using the se- lected units f or length). •volume distanc e—the distanc e is based on a tar get b oundar y volume and gr owth fac tor. Cells ar e mar ked based on the f ollowing equa tion: (39.1) wher e is the c ell v olume , is the sp ecified b oundar y volume ( Boundar y Volume ), is the e xponen tial gr owth fac tor (Growth F actor), and is the nor mal distanc e of the c ell c entroid from the selec ted b oundar ies. is the tar get v olume f or a c ell. To cr eate a b oundar y cell r egist er: 1.Open the Figur e 39.20: Boundar y Regist er D ialog Box (p.2762 ). Solution → Cell Regist ers New → Boundar y... 2761Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using C ell R egist ersFigur e 39.20: Boundar y Regist er D ialo g Box 2.Choose whether the b oundar y regist er is based on Cell D istanc e,Normal D istanc e, or Volume D istanc e. 3.Specify the Numb er of C ells,Distanc e Threshold , or Boundar y Volume and Growth F actor, dep ending on which distanc e metho d you selec ted in the pr evious st ep. 4.Selec t the b oundar y zone(s) f or the c ell regist er. 5.Click Save to create the c ell regist er. Note You c an change the w ay the r egist er is displa yed b y using the Cell R egist er D ispla y Options D ialog Box (p.3788 ) dialo g box tha t op ens b y click ing Displa y Options .... 39.2.3. Variable Limit er Limit r egist ers allo w you t o mar k the c ells tha t ha ve reached a solution limit while solving .These limits can b e view ed and mo dified in Figur e 37.11: The S olution Limits D ialog Box (p.2599 ). For additional in- formation on solution limits , see Setting S olution Limits (p.2599 ). To cr eate a limit c ell r egist er: 1.Open the Figur e 39.21: Limit R egist er D ialog Box (p.2763 ). Solution → Cell Regist ers New → Variable Limit er... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2762Creating Sur faces and C ell R egist ers f or D ispla ying and R eporting D ataFigur e 39.21: Limit Regist er D ialo g Box 2.Selec t the v ariable f or cr eating the c ell regist er. 3.Click Save to create the c ell regist er. Note You c an change the w ay the r egist er is displa yed b y using the Cell R egist er D ispla y Options D ialog Box (p.3788 ) dialo g box tha t op ens b y click ing Displa y Options .... 39.2.4. Field Variable Field v ariable r egist ers allo w you t o mar k cells based on the v alue of a field v ariable . Additionally , you can sp ecify if these field v ariable v alues ar e der ived, and if so , whether it is via gr adien t or cur vature. You c an also sc ale the v alues b y the z onal or global a verage or maximum. You c an mar k cells based on the minimum/maximum v alue of a field v ariable , inside or outside of a c ertain r ange of field v ariable values , within a c ertain p ercentage of the minimum/maximum v alue of a field v ariable , or b y the t op or lo w value . 39.2.4.1. Appr oaches F or D eriving F ield Values There ar e thr ee appr oaches f or using the a vailable ph ysical features of the flo w field t o mar k cells available in ANSY S Fluen t: •Gradien t appr oach : In this appr oach, ANSY S Fluen t multiplies the E uclidean nor m of the gr adien t of the selec ted solution v ariable b y a char acteristic length sc ale [27] (p.4006 ). For e xample , the gr adien t func tion in two dimensions has the f ollowing f orm: (39.2) wher e is the er ror indic ator, is the c ell ar ea, is the gr adien t volume w eigh t, and is the E uclidean nor m of the gr adien t of the desir ed field v ariable , . The default v alue of the gr adien t volume w eigh t is unit y, which c orresponds t o full v olume weigh ting . A v alue of z ero will elimina te the v olume w eigh ting , and v alues b etween 0 and 1 will use pr oportional w eigh ting of the v olume . This appr oach is r ecommended f or pr oblems with str ong sho cks, for e xample , sup ersonic in viscid flows. 2763Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using C ell R egist ers•Curvature appr oach :This is an equidistr ibution mar king t echnique tha t multiplies the undivided Laplacian of the selec ted solution v ariable b y a char acteristic length sc ale [140] (p.4012 ). For e xample , the gr adien t func tion in t wo dimensions has the f ollowing f orm: (39.3) wher e is the er ror indic ator, is the c ell ar ea, is the gr adien t volume w eigh t, and is the undivided Laplacian of the desir ed field v ariable ( ). The default v alue of the gr adien t volume w eigh t is unit y, which c orresponds t o full v olume weigh ting . A v alue of z ero will elimina te the v olume w eigh ting , and v alues b etween 0 and 1 will use pr oportional w eigh ting of the v olume . This appr oach is r ecommended f or pr oblems with smo oth solutions . •Isovalue appr oach :This appr oach is not based on der ivatives. Inst ead, the iso values of the r equir ed field variable , are used t o control the mar king.Therefore, the func tion is of the f orm: (39.4) wher e is the er ror indic ator.This appr oach is r ecommended f or pr oblems wher e der ivatives ar e not helpful. For e xample , if y ou w ant to mar k the mesh wher e the r eaction is tak ing plac e, you c an use the iso values of the r eaction r ate and mar k at high r eaction r ates.This appr oach also allo ws you t o cust omiz e the cr iteria for c ontrolling the mar king using cust om field func tions , user-defined scalars , and so on Any of the field v ariables a vailable f or c ontours displa y can b e used in the mar king c ell gr adien ts. These sc alar func tions include b oth geometr ic and ph ysical features of the numer ical solution. Therefore, in addition t o traditional mar king based on ph ysical features, such as the v elocity, you ma y choose t o mar k to the c ell v olume field t o reduc e rapid v ariations in c ell v olume . In addition t o the standar d (no nor maliza tion) appr oach a vailable in ANSY S Fluen t, four options ar e available f or nor maliza tion [38] (p.4007 ): •Scale b y Global A verage , scales the v alues of , , or by their a verage v alue in the domain, tha t is: (39.5) •Scale b y Zone A verage scales the v alues of , , or by their a verage v alue in each z one . •Scale b y Global M aximum , scales the v alues of , , or by their maximum v alue in the domain, ther efore alw ays retur ning a pr oblem-indep enden t range of [0, 1] for an y variable used f or mar king, tha t is: (39.6) •Scale b y Zone M aximum , scales the v alues of , , or by their maximum v alue in each z one , ther efore alw ays retur ning a pr oblem-indep enden t range of [0, 1] for an y variable used f or mar king. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2764Creating Sur faces and C ell R egist ers f or D ispla ying and R eporting D ata39.2.4.2. Setting Up a F ield Variable C ell R egist er To cr eate a field v ariable c ell r egist er: 1.Open the Figur e 39.22: Field Variable R egist er D ialog Box (p.2765 ). Solution → Cell Regist ers New → Field Variable ... Figur e 39.22: Field Variable Regist er D ialo g Box 2.Choose the Type of field v ariable r egist er. Note tha t you c an use Comput e to calcula te the minimum and maximum v alues of the chosen field v ariable .Your options include: •Min/M ax Value C ells cells c ontaining the minimum and maximum v alues of the sp ecified field v ariable will b e mar ked. •Cells in R ange cells with iso values b etween Iso-M in and Iso-M ax will b e mar ked. •Cells L ess Than cells with v alues tha t are less than the sp ecified thr eshold v alue will b e mar ked. •Cells M ore Than cells with v alues tha t are gr eater than the sp ecified thr eshold v alue will b e mar ked. •Cells Outside R ange cells with iso values less than Iso-M in or gr eater than Iso-M ax will b e mar ked. •Top Value C ells cells with v alues within the t op 'n' p ercent will b e mar ked. •Low Value C ells cells with v alues within the lo west 'n' p ercent will b e mar ked. 2765Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using C ell R egist ers3.Specify ho w the field v ariable v alues ar e der ived in the Derivative Option drop-do wn. You c an cho ose from: •None •Gradien t •Curvature 4.Specify ho w the field v ariable v alues ar e sc aled in the Scaling Option drop-do wn. You c an cho ose fr om: •None •Scale b y Global A verage •Scale b y Zone A verage •Scale b y Global M aximum •Scale b y Zone M aximum 5.Selec t the field v ariable f or cr eating the c ell regist er fr om the Field Values of drop-do wn lists .The name of this field will change based on the selec tions y ou mak e for der ivativ e and sc aling options . 6.Click Save to create the c ell regist er. Note You c an change the w ay the r egist er is displa yed b y using the Cell R egist er D ispla y Options D ialog Box (p.3788 ) dialo g box tha t op ens b y click ing Displa y Options .... 39.2.5. Residuals Residual r egist ers allo w you t o mar k cells based on their r esiduals v alues .You c an visualiz e the c ells with the highest r esidual v alues and k now their lo cation so tha t you c an mo dify them as nec essar y. To cr eate a r esidual c ell r egist er: 1.Open the Figur e 39.23: Residual R egist er D ialog Box (p.2767 ). Solution → Cell Regist ers New → Residuals ... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2766Creating Sur faces and C ell R egist ers f or D ispla ying and R eporting D ataFigur e 39.23: Residual Regist er D ialo g Box 2.Selec t the Equa tion (s) for cr eating the r esidual c ell regist er. 3.Specify the Threshold P ercent for cr eating the r esidual c ell regist er. Cells with r esidual v alues ab ove this threshold f or the selec ted equa tions ar e mar ked. 4.Click Save to create the c ell regist er. Note You c an change the w ay the r egist er is displa yed b y using the Cell R egist er D ispla y Options D ialog Box (p.3788 ) dialo g box tha t op ens b y click ing Displa y Options .... 39.2.6. Volume Volume r egist ers allo w you t o mar k cells based on the v olume of the c ells, either the magnitude or the change in v olume . 39.2.6.1. Volume C ell R egist er A ppr oach Marking the mesh based on v olume magnitude is of ten used t o iden tify lar ge c ells.The pr ocedur e is to mar k cells with a v olume gr eater than the sp ecified thr eshold v olume . Marking the mesh based on the change in c ell v olume is used t o iden tify ar eas wher e you ma y want to impr ove the smo othness of the mesh. The pr ocedur e is t o mar k an y cell tha t has a v olume change greater than the sp ecified thr eshold v alue .The v olume change is c omput ed b y looping o ver the fac es and c ompar ing the r atio of the c ell neighb ors t o the fac e. 2767Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using C ell R egist ersFor e xample , in Figur e 39.24: Volume C hange—R atio of the Volumes of the C ells (p.2768 ) the r atio of V1/V2 and the r atio of V2/V1 is c ompar ed t o the thr eshold v alue . If V2/V1 is gr eater than the thr eshold , then C2 is mar ked. Figur e 39.24: Volume C hange—R atio of the Volumes of the C ells 39.2.6.2. Setting Up a Volume C ell R egist er To cr eate a v olume c ell r egist er: 1.Open the Figur e 39.25: Volume R egist er D ialog Box (p.2768 ). Solution → Cell Regist ers New → Volume ... Figur e 39.25: Volume Regist er D ialo g Box 2.Choose whether the c ell regist er is based on the maximum siz e of the c ells ( Magnitude ) or the Change in volume of the c ells. 3.Specify the Max Volume or Max Volume C hange . Note tha t you c an click Comput e to comput e the minimum and maximum c ell v olumes . 4.Click Save to create the c ell regist er. Note You c an change the w ay the r egist er is displa yed b y using the Cell R egist er D ispla y Options D ialog Box (p.3788 ) dialo g box tha t op ens b y click ing Displa y Options .... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2768Creating Sur faces and C ell R egist ers f or D ispla ying and R eporting D ata39.2.7. Yplus/Ystar Yplus/Ystar r egist ers allo w you t o mar k cells based on their Yplus/Ystar v alues . 39.2.7.1. Yplus/Ystar A ppr oach The appr oach is t o comput e or for b oundar y cells on the sp ecified visc ous w all z ones , define the minimum and maximum allo wable or , and mar k the appr opriate cells. Cells with or values b elow the minimum allo wable thr eshold will b e mar ked, as will c ells with or values ab ove the maximum allo wable thr eshold . Figur e 39.26: Airfoil Wall C ells M arked b y Y+ Values (p.2769 ) sho ws a mesh cr eated t o solv e the flo w over an air foil, wher e the b ottom b oundar y of the mesh tha t is sho wn is the t op sur face of the air foil. After an initial solution, it w as det ermined tha t values of some of the c ells on the t op sur face were too lar ge, and was used t o mar k them. Figur e 39.26: Airfoil Wall C ells M arked b y Y+ Values 39.2.7.2. Setting up a Yplus/Ystar C ell R egist er To cr eate a Yplus/Ystar c ell r egist er: 1.Open the Figur e 39.27: Yplus/Ystar R egist er D ialog Box (p.2770 ). Solution → Cell Regist ers New → Yplus/Ystar ... 2769Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using C ell R egist ersFigur e 39.27: Yplus/Ystar Regist er D ialo g Box 2.Choose whether the c ell regist er is based on Yplus or Ystar values . 3.Selec t the Wall Z ones for the Yplus or Ystar c alcula tions . 4.Specify the minimum and maximum Yplus/Ystar v alues allo wed. Note tha t click ing Comput e calcula tes the minimum and maximum Yplus/Ystar v alues . 5.Click Save to create the c ell regist er. Note You c an change the w ay the r egist er is displa yed b y using the Cell R egist er D ispla y Options D ialog Box (p.3788 ) dialo g box tha t op ens b y click ing Displa y Options .... 39.2.8. Manage C ell Regist ers The Figur e 39.28: Manage C ell R egist ers D ialog Box (p.2771 ) allo ws you t o review the pr operties of the currently defined c ell r egist ers.You c an also use it t o displa y and delet e the selec ted c ell r egist er. To manage c ell r egist ers: 1.Open the Figur e 39.28: Manage C ell R egist ers D ialog Box (p.2771 ). Solution → Cell Regist ers Edit... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2770Creating Sur faces and C ell R egist ers f or D ispla ying and R eporting D ataFigur e 39.28: Manage C ell Regist ers D ialo g Box 2.Selec t a c ell regist er to: view its pr operties, displa y it, or delet e it. 39.2.9. Cell Regist er Op erations Onc e a c ell r egist er is defined , you c an cr eate a c ell r egist er op eration t o report the r esidual v alues of the selec ted c ell r egist ers a t the in terval you sp ecify . To cr eate a r egist er report: 1.Open the Figur e 39.29: Report Regist er D ialog Box (p.2772 ). Solution → Calcula tion A ctivities → Cell Regist er Op erations New Rep ort... 2771Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using C ell R egist ersFigur e 39.29: Rep ort Regist er D ialo g Box Note that this dialo g box is onl y available af ter y ou ha ve defined a c ell r egist er. 2.Selec t the c ell regist er(s) y ou w ant included in the r eport. 3.Specify the r eporting Frequenc y. 4.Specify the maximum numb er of c ells t o include in the r eport. 5.Click Save to create the c ell regist er report. The Figur e 39.30: Manage R egist er Op erations D ialog Box (p.2773 ) allo ws you t o view pr operties, create, modify, and delet e report regist ers. Solution → Calcula tion A ctivities → Cell Regist er Op erations Edit... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2772Creating Sur faces and C ell R egist ers f or D ispla ying and R eporting D ataFigur e 39.30: Manage Regist er Op erations D ialo g Box 39.2.10. Copying and Renaming C ell Regist ers The pr ocedur es for c opying a c ell r egist er is as f ollows: 1.In the Outline View, right-click the name of a c ell regist er tha t you w ant to copy (under Setup/S olu- tion/C ell Regist ers) and selec t Copy... to op en the c orresponding r egist er dialo g box. 2.Enter the new name in the Name field and click Save/D ispla y. A new r egist er will b e added under the Cell Regist ers branch in the Outline View. This is useful if y ou w ant to cr eate a c ell r egist er with similar pr operties. To change the name of a r egist er: 1.In the Outline View, selec t the c ell regist er you w ant to rename . It becomes highligh ted. 2.Click the highligh ted name again or pr ess F2 to en ter the edit mo de. 3.Type the new name and click outside of the name field t o sa ve it. This pr ocedur e is similar t o changing file names in Windo ws Explor er. 2773Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using C ell R egist ersRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2774Chapt er 40: Displa ying G raphics Graphics t ools a vailable in ANSY S Fluen t enable y ou t o pr ocess the inf ormation c ontained in y our CFD solution and easily view the r esults .The f ollowing sec tions e xplain ho w to use these t ools t o examine your solution. The pr ocedur e for sa ving pic ture files of gr aphics displa ys is descr ibed in Saving P icture Files (p.645). 40.1. Basic G raphics G ener ation 40.2. Customizing the G raphics D ispla y 40.3. Controlling the M ouse B utton F unctions 40.4. Viewing the A pplic ation Windo w 40.5. Modifying the View 40.6. Advanced Sc ene C omp osition 40.7. Anima ting G raphics 40.8. Hist ogram and X Y Plots 40.9. Turbomachiner y Postpr ocessing 40.10. Fast F ourier Transf orm (FFT ) Postpr ocessing 40.1. Basic G raphics G ener ation In ANSY S Fluen t, you c an gener ate gr aphics displa ys sho wing meshes , contours , profiles , vectors, pathlines , and sc enes . Some gr aphics ar e gener ated using v ariables tha t are plott ed dir ectly fr om the ANSY S Flu- ent da ta file onc e the file has b een r ead.The v ariables list ed in the da ta file dep end on the mo dels active at the time the file is wr itten.Variables tha t are requir ed b y the solv er, based on the cur rent model settings , but ar e missing fr om the da ta file ar e set t o their default v alues . For those missing variables , one it eration should b e performed in or der t o obtain the r equir ed v alues f or gener ating the plot. A c omplet e list of v ariables st ored in the da ta file is a vailable in (xfile.h ) and c an b e acc essed as sta ted in Data S ections (p.3984 ).The f ollowing sec tions descr ibe ho w to cr eate these plots . (Gener ation of hist ogram and X Y plots is discussed in Hist ogram and X Y Plots (p.2862 ).) Imp ortant If your mo del includes a discr ete phase , you c an also displa y the par ticle tr ajec tories, as de- scribed in Displa ying of Trajec tories (p.2028 ). Note There ar e two kinds of gr aphics objec ts—those whose settings ar e sa ved with the c ase file for reuse dur ing the simula tion, and those tha t are not. Persist ent graphics objec ts (sa ved with the c ase file) ar e acc essed b y click ing New..., non-p ersist ent objec ts ar e created b y click ing Edit.... For e xample , you c an cr eate a p ersist ent contour plot b y click ing Contours and selec ting New... in the Results ribbon tab ( Graphics group b ox). Results → Graphics → Contours → New... 2775Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.This sec tion discusses the f ollowing t opics: 40.1.1. Displa ying the M esh 40.1.2. Displa ying C ontours and P rofiles 40.1.3. Displa ying Vectors 40.1.4. Displa ying P athlines 40.1.5. Displa ying a Sc ene 40.1.6. Displa ying R esults on a S weep Sur face 40.1.7. Hiding the G raphics Windo w D ispla y 40.1.1. Displa ying the M esh During the pr oblem setup or when y ou ar e examining y our solution, you ma y want to lo ok a t the mesh asso ciated with c ertain sur faces.You c an do the f ollowing: •Displa y the outline of all or par t of the domain, as sho wn in Figur e 40.1: Outline D ispla y (p.2776 ). Figur e 40.1: Outline D ispla y •Draw the mesh lines (edges), as sho wn in Figur e 40.2: Mesh E dge D ispla y (p.2777 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2776Displa ying G raphicsFigur e 40.2: Mesh E dge D ispla y •Draw the solid sur faces (filled meshes) f or a 3D domain, as sho wn in Figur e 40.3: Mesh F ace (Filled Mesh) D ispla y (p.2777 ). Figur e 40.3: Mesh F ace (F illed M esh) D ispla y 2777Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Basic G raphics G ener ation•Draw the no des on the domain sur faces, as sho wn in Figur e 40.4: Node D ispla y (p.2778 ). Figur e 40.4: Node D ispla y Note The Post P rocessing option f or mesh displa y configur ation is r ecommended when p ostpr o- cessing y our r esults in ANSY S Fluen t.This option is acc essed b y click ing in the objec ts toolbar or b y en tering dislay/set/mesh-display-configuration in the c onsole . For inf ormation ab out displa ying the mesh on a sur face tha t sw eeps thr ough the domain, see Displa ying Results on a S weep Sur face (p.2813 ). 40.1.1.1. Gener ating Mesh or O utline P lots You c an dr aw the mesh or outline f or all or par t of y our domain using the Mesh D ispla y Dialog Box (p.3239 ) (Figur e 40.5: The M esh D ispla y Dialog Box (p.2779 )). Results → Graphics → Mesh Edit... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2778Displa ying G raphicsFigur e 40.5: The M esh D ispla y D ialo g Box The basic st eps f or gener ating a mesh or outline plot ar e as f ollows: 1. Choose the sur faces for which y ou w ant to displa y the mesh or outline in the Surfaces list. If you w ant to selec t several sur faces of the same t ype, click and selec t Surface Type under Group B y, which or ganiz es the sur faces in a tr ee view tha t is gr oup ed b y sur face type. Another shor tcut is t o use the Filter Text entry box to filt er the Surfaces list t o sho w only the surfaces tha t ma tch the pa ttern you en ter. For additional inf ormation on using the Filter Text entry box, see Filter Text En try Boxes (p.565). 2. Depending on wha t you w ant to dr aw, do one or mor e of the f ollowing: •To dr aw an outline of the selec ted sur faces (as in Figur e 40.1: Outline D ispla y (p.2776 )), selec t Edges under Options and Outline under Edge Type. If you need mor e detail in the outline displa y of a comple x geometr y, see the descr iption of the Feature option, below. 2779Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Basic G raphics G ener ation•To dr aw the mesh edges (as in Figur e 40.2: Mesh E dge D ispla y (p.2777 )), selec t Edges under Options and All under Edge Type. •To gener ate a filled-mesh displa y (as in Figur e 40.3: Mesh F ace (Filled M esh) D ispla y (p.2777 )), selec t Faces under Options . •To dr aw the no des on the selec ted sur faces (as in Figur e 40.4: Node D ispla y (p.2778 )), selec t Nodes under Options . 3. Set an y of the mesh and outline displa y options descr ibed in the f ollowing sec tion. 4. Click Displa y to dr aw the sp ecified mesh or outline in the ac tive gr aphics windo w. To displa y filled meshes , with smo othly shaded displa y, enable ligh ting and selec t a ligh ting in terpol- ation metho d other than Flat in the Displa y Options D ialog Box (p.3681 ) or the Ligh ts D ialog Box (p.3696 ). If you displa y no des, and y ou w ant to change the symb ol represen ting the no des, you c an change the Point Symb ol in the Displa y Options D ialog Box (p.3681 ). See Modifying the R ender ing Op- tions (p.2831 ) for details . 40.1.1.2. Mesh and O utline D ispla y O ptions The options men tioned in the pr ocedur e in the pr evious sec tion include mo difying the mesh c olors , adding the outline of imp ortant features to an outline displa y, drawing par tition b oundar ies, and shrinking the fac es and/or c ells in the displa y. 40.1.1.2.1. Mo difying the Mesh C olors ANSY S Fluen t enables y ou t o control the c olors tha t are used t o render the meshes f or each z one type or sur face.This c apabilit y can help y ou t o understand mesh plots quick ly and easily .To mo dify the c olors , open the Mesh C olors D ialog Box (p.3244 ) (Figur e 40.6: The M esh C olors D ialog Box (p.2780 )) by click ing Colors ... in the Mesh D ispla y Dialog Box (p.3239 ). Figur e 40.6: The M esh C olors D ialo g Box You c an set c olors individually f or the meshes displa yed on each sur face, using the Scene D escr iption Dialog Box (p.3683 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2780Displa ying G raphicsBy default , the Color b y Type option is tur ned on, enabling y ou t o assign c olors based on z one type.To change the c olor used t o dr aw the mesh f or a par ticular z one t ype, selec t the z one t ype in the Types list and then selec t the new c olor in the Colors list. You will see the eff ect of y our change when y ou ne xt displa y the mesh. Note tha t the surface type in the Types list applies t o all sur face meshes (tha t is, meshes tha t are dr awn f or sur faces cr eated using the dialo g boxes op ened fr om the Create butt on in the Surface group b ox of the Domain ribbon tab) e xcept z one sur faces. If you pr efer to use the c olors ANSY S Fluen t assigns b y zone ID , then y ou c an displa y the mesh using the Color b y ID option. Note By default , walls ar e color ed b y preferenc e color , which indic ates tha t the c olor of the walls will change based on the Graphics C olor Theme specified in Preferenc es (available from the File ribbon tab). For e xample , if y ou change the c olor theme fr om Gray Gradien t to Black , the w all c olor will aut oma tically change fr om black t o whit e to main tain visibilit y (when preferenc e color is selec ted f or w alls). 40.1.1.2.2. Adding F eatur es t o an O utline D ispla y For closed 3D geometr ies such as c ylinders , the standar d outline displa y of ten will not sho w enough detail t o accur ately depic t the shap e.This is b ecause f or each b oundar y, only those edges on the “outside ” of the geometr y (tha t is, those tha t are used b y only one fac e on the b oundar y) ar e dr awn. In Figur e 40.7: Standar d Outline of C omple x Duct (p.2781 ), which sho ws the outline displa y for a complic ated duc t geometr y, only the inlet and outlet ar e visible . Figur e 40.7: Standar d Outline of C omple x Duct 2781Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Basic G raphics G ener ationFigur e 40.8: Feature Outline of C omple x Duct You c an c aptur e additional f eatures using the Feature option in the Mesh D ispla y Dialog Box (p.3239 ). (See Figur e 40.8: Feature Outline of C omple x Duct (p.2782 ).) Enable Feature under Edge Type, and then set the Feature Angle .With the default Feature Angle of 20, if the diff erence between the normal dir ections of t wo adjac ent fac es is mor e than 20°, the edge b etween those fac es will b e drawn. Decreasing the Feature Angle will r esult in mor e edge lines (tha t is, mor e detail) b eing added to the outline displa y.The appr opriate angle f or y our geometr y will dep end on its cur vature and comple xity.You c an mo dify the Feature Angle until you find the v alue tha t yields the b est outline displa y. 40.1.1.2.3. Drawing P artition B oundaries If you ha ve par titioned y our mesh f or par allel pr ocessing , you c an add the displa y of par tition boundar ies t o the mesh displa y by tur ning on the Partitions option in the Mesh D ispla y Dialog Box (p.3239 ). 40.1.1.2.4. Shrink ing F aces and C ells in the D ispla y To distinguish individual fac es or c ells in the displa y, enlar ge the spac e between adjac ent fac es or cells b y incr easing the Shrink F actor in the Mesh D ispla y Dialog Box (p.3239 ).The default v alue of zero pr oduces a displa y in which the edges of adjac ent fac es or c ells o verlap. A v alue of 1 cr eates the opp osite extreme: each fac e or c ell is r epresen ted b y a p oint and ther e is c onsider able spac e between each one . A small v alue such as 0.01 ma y be lar ge enough t o enable y ou t o distinguish one fac e or c ell fr om its neighb or. Displa ys with diff erent Shrink F actor values ar e sho wn in Fig- ure 40.9: Mesh D ispla y with S hrink F actor = 0 (p.2783 ) and Figur e 40.10: Mesh D ispla y with S hrink Factor = 0.01 (p.2783 ). Click Displa y to see the eff ect of the change in Shrink F actor. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2782Displa ying G raphicsFigur e 40.9: Mesh D ispla y with S hrink F actor = 0 Figur e 40.10: Mesh D ispla y with S hrink F actor = 0.01 40.1.1.3. Creating and Using Mesh P lot D efinitions You c an cr eate named mesh plot definitions and sa ve them f or la ter use . See Creating and U sing Contour P lot D efinitions (p.2792 ) for additional inf ormation on gr aphics objec t definitions . 2783Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Basic G raphics G ener ationThe st eps f or cr eating and using mesh plot definitions ar e similar t o the st eps f or Gener ating M esh or Outline P lots (p.2778 ), with the addition of a field f or naming the mesh plot definition. 40.1.2. Displa ying C ontours and P rofiles ANSY S Fluen t enables y ou t o plot c ontour lines or pr ofiles sup erimp osed on the ph ysical domain. Contour lines ar e lines of c onstan t magnitude f or a selec ted v ariable (isother ms, isobars , and so on). A pr ofile plot dr aws these c ontours pr ojec ted off the sur face along a r eference vector b y an amoun t proportional t o the v alue of the plott ed v ariable a t each p oint on the sur face. Sample plots ar e sho wn in Figur e 40.11: Contours of S tatic P ressur e (p.2784 ) and Figur e 40.12: Profile P lot of y Velocity (p.2785 ). For inf ormation ab out displa ying c ontours or pr ofiles on a sur face tha t sw eeps thr ough the domain, see Displa ying R esults on a S weep Sur face (p.2813 ). Figur e 40.11: Contours of S tatic P ressur e Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2784Displa ying G raphicsFigur e 40.12: Profile P lot of y Velocity 40.1.2.1. Gener ating C ont our and P rofile P lots You c an plot c ontours or pr ofiles using the Contours D ialog Box (p.3790 ) (Figur e 40.13: The C ontours Dialog Box (p.2786 )). Results → Graphics → Contours Edit... 2785Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Basic G raphics G ener ationFigur e 40.13: The C ontours D ialo g Box The basic st eps f or gener ating a c ontour or pr ofile plot ar e as f ollows: 1. Selec t the v ariable or func tion t o be contoured or pr ofiled in the Contours of drop-do wn list. First selec t the desir ed c ategor y in the upp er list; you ma y then selec t a r elated quan tity in the lo wer list. (See Field Function D efinitions (p.2959 ) for an e xplana tion of the v ariables in the list.) 2. Choose the sur face or sur faces on which t o dr aw the c ontours or pr ofiles in the Surfaces list. For 2D cases , if no sur face is selec ted, contouring or pr ofiling is done on the en tire domain. For 3D c ases , you must alw ays selec t at least one sur face. If you w ant to selec t several sur faces of the same t ype, click and selec t Surface Type under Group B y, which or ganiz es the sur faces in a tr ee view tha t is gr oup ed b y sur face type. Another shor tcut is t o use the Filter Text entry box to filt er the Surfaces list t o sho w only the surfaces tha t ma tch the pa ttern you en ter. For additional inf ormation on using the Filter Text entry box, see Filter Text En try Boxes (p.565). 3. Specify the numb er of c ontours or pr ofiles in the Levels field .The maximum numb er of le vels allo wed is 100. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2786Displa ying G raphics4. If you ar e gener ating a pr ofile plot , enable the Draw P rofiles option. In the r esulting Profile Options Dialog Box (p.3663 ) (Figur e 40.14: The P rofile Options D ialog Box (p.2787 )) you will define the pr ofiles . Figur e 40.14: The P rofile Options D ialo g Box a. Set the “zero heigh t” reference value f or the pr ofile ( Referenc e Value ) and the length sc ale fac tor for pr ojec tion ( Scale F actor). Any point on the pr ofile with a v alue equal t o the Referenc e Value will b e plott ed e xactly on the defining sur face.Values gr eater than the Referenc e Value will b e projec ted ahead of the sur face (in the dir ection of Projec tion D ir.) and sc aled b y Scale F actor), and v alues less than the Referenc e Value will b e pr ojec ted b ehind the sur face and sc aled . These par amet ers c an b e used t o cr eate fuller pr ofiles when y ou need t o displa y the v ariation in a v ariable tha t is small c ompar ed t o the absolut e value of the v ariable . Consider , for e x- ample , the displa y of t emp erature pr ofiles when the t emp erature range in the domain is from 300 K t o 310 K. The 10 K r ange in the t emp erature will b e har d to det ect when pr ofiles are dr awn using the default sc aling (which will b e based on the absolut e magnitude of 310 K). To cr eate a fuller pr ofile , you c an set the Referenc e Value to 300 and the pr ofile Scaling F actor to 5 (f or e xample) t o magnify the displa y of the r emaining 10 K r ange . In subsequen t displa y of the pr ofiles , the r eference value of 300 will b e eff ectively subtr acted from the da ta b efore displa y so tha t the t emp eratures of 300 K will not b e off set fr om the baselines .The pr ofiles will then r eflec t only the v ariation of t emp erature from 300 K. b.Set the dir ection in which pr ofiles ar e pr ojec ted ( Projec tion D ir.). In 2D , for e xample , a contour plot of pr essur e on the en tire domain c an b e pr ojec ted in the direction t o form a c arpet plot , or a contour plot of velocity on a sequenc e of -coordina te slic e lines c an b e pr ojec ted in the direction t o form a ser ies of v elocity pr ofiles (as sho wn in Figur e 40.12: Profile P lot of y Velo- city (p.2785 )). c.Click Apply and close the Profile Options D ialog Box (p.3663 ). 5. Set an y of the c ontour and pr ofile plot options descr ibed b elow. 6. Click Displa y to dr aw the sp ecified c ontours or pr ofiles in the ac tive gr aphics windo w. The r esulting displa y will include the sp ecified numb er of c ontours or pr ofiles of the selec ted v ariable , with the magnitude on each one det ermined b y equally incr emen ting b etween the v alues sho wn in the Min and Max fields . 2787Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Basic G raphics G ener ation40.1.2.2. Cont our and P rofile P lot O ptions The options men tioned in the pr ocedur e ab ove include dr awing c olor-filled c ontours/pr ofiles (inst ead of the default line c ontours/pr ofiles), specifying a r ange of v alues t o be contoured or pr ofiled , including portions of the mesh in the c ontour or pr ofile displa y, cho osing no de or c ell v alues f or displa y, and storing the c ontour or pr ofile plot settings . 40.1.2.2.1. Drawing F illed C ont ours or P rofiles Color-filled c ontour or pr ofile plots sho w a c ontour or pr ofile displa y containing a c ontinuous c olor displa y (see Figur e 40.15: Filled C ontours of S tatic P ressur e (p.2788 )), inst ead of just dr awing lines represen ting sp ecific v alues . Note tha t a c olor-filled pr ofile displa y is of ten r eferred t o as a “carpet plot ”.To gener ate a filled c ontour or pr ofile plot , enable the Filled option in the Contours D ialog Box (p.3790 ) dur ing st ep 5 in the pr evious sec tion. Figur e 40.15: Filled C ontours of S tatic P ressur e To displa y smo othly shaded filled c ontours , you must enable ligh ting and selec t a ligh ting in terpol- ation metho d other than Flat in the Displa y Options D ialog Box (p.3681 ) or the Ligh ts D ialog Box (p.3696 ).You will not get smo oth shading of filled c ontours if the Clip t o Range option is tur ned on. Smooth shading of filled pr ofiles is not a vailable . Note The Draw P rofile option settings ar e not sa ved with the c ontour plot definition. Onc e the dialo g box is closed these options will r evert to being disabled . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2788Displa ying G raphics40.1.2.2.2. Specifying the R ange of M agnitudes D ispla yed By default , the minimum and maximum v alues c ontoured or pr ofiled ar e set based on the r ange of values in the en tire domain. This means tha t the c olor sc ale will star t at the smallest v alue in the domain (sho wn in the Min field) and end a t the lar gest v alue (sho wn in the Max field). If you ar e plotting c ontours or pr ofiles on a subset of the domain (tha t is, on a sur face), your plot ma y cover only the midr ange of the c olor sc ale. For e xample , if blue c orresponds t o 0 and r ed c orresponds t o 10, and the v alues on y our sur face range only fr om 4 t o 6, your plot will c ontain mostly gr een c ontours or pr ofiles , sinc e gr een is the c olor a t the middle of the default c olor sc ale. •To focus in on a smaller r ange of v alues , so tha t blue c orresponds t o 4 and r ed t o 6, manually r eset the range t o be displa yed.You c an also use the minimum and maximum v alues on the selec ted sur- faces—r ather than in the en tire domain—t o det ermine the r ange . Another r eason t o manually set the range is if y ou ar e interested only in c ertain v alues . For e xample , if you w ant to det ermine the r egion wher e pr essur e exceeds a c ertain v alue , you c an incr ease the minimum v alue f or displa y so tha t the lo wer pressur e values ar e not displa yed. •To manually set the c ontour/pr ofile r ange , turn off the Auto Range option in the Contours D ialog Box (p.3790 ).The Min and Max fields will b ecome editable , and y ou c an en ter the new r ange of v alues t o be displa yed. –To sho w the default r ange a t an y time , click Comput e and the Min and Max fields will b e up dated. –If you ar e dr awing filled c ontours or pr ofiles y ou c an c ontrol whether or not v alues outside the pr e- scribed Min/ Max range ar e displa yed. •To lea ve areas in which the v alue is outside the sp ecified r ange empt y (tha t is, draw no c ontours or pr ofiles), enable the Clip t o Range option. This is the default setting . If you tur n Clip t o Range off, values b elow the Min value will b e color ed with the lo west c olor on the c olor sc ale, and v alues ab ove the Max value will b e color ed with the highest c olor on the c olor sc ale.Figur e 40.16: Filled C ontours with C lip t o Range On (p.2790 ) and Figur e 40.17: Filled C ontours with C lip t o Range O ff (p.2790 ) sho w the r esults of enabling/dis- abling the Clip t o Range option. •To base the minimum and maximum v alues on the r ange of v alues on the selec ted sur faces, rather than in the en tire domain, turn off the Global R ange option in the Contours D ialog Box (p.3790 ).The Min and Max values will b e up dated when y ou ne xt click Comput e or Displa y. 2789Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Basic G raphics G ener ationFigur e 40.16: Filled C ontours with C lip t o Range On Figur e 40.17: Filled C ontours with C lip t o Range O ff Note When Global R ange is enabled , Fluen t only c omput es and p opula tes the r ange when: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2790Displa ying G raphics1.You click Comput e. 2.Auto Range is enabled . If Auto R ange is disabled , the r ange will r emain the same until y ou click Comput e, even if you selec t a ne w v ariable f or displa y. 40.1.2.2.3. Including the Mesh in the C ont our P lot For some pr oblems , esp ecially c omple x 3D geometr ies, you ma y want to include p ortions of the mesh in y our c ontour or pr ofile plot as spa tial r eference points. For e xample , you ma y want to sho w the lo cation of an inlet and an outlet along with the c ontours .This is acc omplished b y tur ning on the Draw M esh option in the Contours D ialog Box (p.3790 ).The Mesh D ispla y Dialog Box (p.3239 ) will app ear aut oma tically when y ou enable the Draw M esh option, and y ou c an set the mesh displa y paramet ers ther e.When y ou click Displa y in the Contours D ialog Box (p.3790 ), the mesh displa y, as defined in the Mesh D ispla y Dialog Box (p.3239 ), will b e included in the c ontour or pr ofile plot. Note The Draw M esh option settings ar e not sa ved with the c ontour plot definition. Onc e the dialo g box is closed these options will r evert to being disabled . To include the mesh with a c ontour plot tha t will b e persist ed with the c ase file , you c an create a mesh plot definition and include b oth the mesh and c ontour plots in a sc ene. See Displa ying a Sc ene (p.2812 ) for mor e details . 40.1.2.2.4. Choosing N ode or C ell Values In ANSY S Fluen t you c an cho ose t o displa y the c omput ed c ell-c enter v alues or v alues tha t ha ve been interpolated t o the no des. By default , the Node Values option is tur ned on, and the in terpolated values ar e displa yed. For line c ontours or pr ofiles , node v alues ar e alw ays used .To displa y filled contours or pr ofiles and t o displa y the c ell v alues , turn off the Node Values option. Filled c ontours/pr o- files of no de v alues will sho w a smo oth gr adation of c olor , while filled c ontours/pr ofiles of c ell v alues may sho w shar p changes in c olor fr om one c ell t o the ne xt. For fac e-only func tions (f or e xample ,Wall S hear S tress), the c ell v alues tha t are displa yed f or boundar y zone sur faces will ac tually b e the fac e values .This is only tr ue in the c ase of b oundar y zone sur faces cr eated f or p ostpr ocessing , wher e the ac tual c ell v alues ar e used f or the par t of the surface tha t lies in the in terior.These fac e values ar e mor e accur ate, as fac e-only func tions ar e comput ed on the fac es and not on the c ells. For mor e inf ormation ab out c ell v alues , see Cell Val- ues (p.2959 ). If you ar e plotting c ontours t o sho w the eff ect of a p orous medium or 2D fan b oundar y, to depic t a sho ck w ave, or t o sho w an y other disc ontinuities or jumps in the plott ed v ariable , you should use cell v alues; if y ou use no de v alues in such c ases , the disc ontinuit y will b e smear ed b y the no de a v- eraging f or gr aphics and will not b e sho wn clear ly in the plot. 40.1.2.2.5. Storing C ont our P lot S ettings For fr equen tly used c ombina tions of c ontour v ariables and options , you c an st ore the inf ormation needed t o gener ate the c ontour plot as f ollows: 2791Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Basic G raphics G ener ation1.In the Contours D ialog Box (p.3790 ), specify a Setup numb er. 2.Set up the desir ed inf ormation in the Contours D ialog Box (p.3790 ). 3.Click Displa y. The settings f or Options ,Contours of ,Min,Max, and Surfaces will b e sa ved. You c an then change the Setup numb er to an unused v alue (tha t is, an ID f or which no inf ormation has b een sa ved) and gener ate a diff erent contour plot. To gener ate a plot using the sa ved setup inf ormation: 1.Change the Setup numb er back t o the v alue f or which y ou sa ved c ontour inf ormation. 2.Click Displa y. You c an sa ve up t o 10 diff erent setups . Imp ortant Note tha t the numb er of c ontour Levels, the sur faces selec ted f or displa y in the Mesh Displa y Dialog Box (p.3239 ) (when the Draw M esh option is ac tivated), and the settings for pr ofiles in the Profile Options D ialog Box (p.3663 ) (when the Draw P rofiles option is activated) will not be sa ved in the Setup , nor will the Setup be sa ved in the c ase file . 40.1.2.3. Creating and Using C ont our P lot D efinitions You c an cr eate named c ontour plot definitions and sa ve them f or la ter use .This c ould b e useful f or demonstr ation pur poses , scene cr eation, or f or p ostpr ocessing the r esults of y our simula tion when varying the settings b etween r uns (t o name a f ew e xamples). The numb er of c ontour plot definitions is not limit ed. To cr eate a c ontour plot definition: Results → Graphics → Contours New... 1.In the Contours D ialog Box (p.3790 ), in the Contour N ame text en try box, enter the name f or y our c ontour plot definition (or acc ept the default name contour- id). Imp ortant Contour and v ector plot definitions must ha ve unique names . 2.Set contour par amet ers and options . TheDraw M esh and Draw P rofile option settings ar e not sa ved with the c ont our plot definition. Once the dialo g box is closed these options will r evert to being disabled . 3.Click Save/D ispla y. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2792Displa ying G raphicsThe sp ecified c ontour will b e displa yed in the ac tive gr aphics windo w, and the new c ontour plot definition with the name y ou ha ve en tered will app ear in the tr ee under Contours . Onc e the c ontour plot definition is cr eated, you c an p erform the f ollowing ac tions using the r ight- click menu c ommands: •Edit the e xisting c ontour plot definition. •Copy the c ontour plot definition. When cr eating a c opy of the e xisting c ontour, you c an mo dify c ontour settings in the Contours dialo g box tha t will op en. •Delete the selec ted c ontour plot definition. •Displa y the c ontour in the gr aphics windo w. •Add the selec ted c ontour t o the plot in the gr aphics windo w. Note tha t while Displa y replac es the cur rent contents of the gr aphics windo w,Add t o gr aphics preser ves the cur rent graphics windo w contents. Note •You c an mo ve the c olor map of c ontour plot definitions b y lef t-click ing and dr agging it t o the desir ed lo cation. The c olor map c an also b e resized b y dr agging the c orners of the b ox tha t app ears when y ou ho ver o ver the c olor map .The c olormap lo cation is not sa ved with the c ont our plot definition. •For 2D c ases , Fluen t aut oma tically cr eates a new sur face when y ou click Save/D ispla y in the Contours dialo g box, if you ha ve not selec ted an y sur faces for displa y. New sur faces ar e only created f or fluid z ones tha t do not alr eady ha ve a sur face defined . These c ommands ar e also a vailable thr ough the t ext user in terface (display/objects ). 2793Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Basic G raphics G ener ation40.1.3. Displa ying Vectors You c an dr aw vectors in the en tire domain, or on selec ted sur faces. By default , one v ector is dr awn a t the c enter of each c ell (or a t the c enter of each fac et of a da ta sur face), with the length and c olor of the ar rows represen ting the v elocity magnitude ( Figur e 40.18: Velocity Vector P lot (p.2794 )).The spacing , size, and c olor ing of the ar rows can b e mo dified , along with se veral other v ector plot settings .Velocity vectors ar e the default , but y ou c an also plot v ector quan tities other than v elocity. Note tha t cell-c enter values ar e alw ays used f or v ector plots; you c annot plot no de-a veraged v alues . For inf ormation ab out displa ying v ectors on a sur face tha t sw eeps thr ough the domain, see Displa ying Results on a S weep Sur face (p.2813 ). Figur e 40.18: Velocity Vector P lot 40.1.3.1. Gener ating Vector P lots You c an plot v ectors using the Vectors D ialog Box (p.3954 ) (Figur e 40.19: The Vectors D ialog Box (p.2795 )). Results → Graphics → Vectors Edit... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2794Displa ying G raphicsFigur e 40.19: The Vectors D ialo g Box The pr ocedur e for gener ating a v ector plot is as f ollows: 1. In the Vectors of drop-do wn list , selec t the v ector quan tity to be plott ed. By default , only v elocity and r elative velocity are available , but y ou c an cr eate your o wn cust om v ectors as descr ibed in Creating and M anaging C ustom Vectors (p.2799 ). Additional v ector options ar e available f or adjoin t solv er results , as descr ibed in Field D ata (p.3144 ). 2. In the Surfaces list, cho ose the sur face(s) on which y ou w ant to displa y vectors. If you w ant to displa y vectors on the en tire domain, selec t none of the sur faces in the list. If you w ant to selec t several sur faces of the same t ype, click and selec t Surface Type under Group B y, which or ganiz es the sur faces in a tr ee view tha t is gr oup ed b y sur face type. Another shor tcut is t o use the Filter Text entry box to filt er the Surfaces list t o sho w only the surfaces tha t ma tch the pa ttern you en ter. For additional inf ormation on using the Filter Text entry box, see Filter Text En try Boxes (p.565). 3. Set an y of the v ector plot options as descr ibed in Vector P lot Options (p.2796 ). 4. Click Displa y to dr aw the v ectors in the ac tive gr aphics windo w. 2795Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Basic G raphics G ener ation40.1.3.2. Displa ying R elativ e Velocity Vectors If you ar e solving y our pr oblem using one or mor e mo ving r eference frames or mo ving meshes , you will ha ve the option t o displa y either the absolut e vectors or the r elative vectors. If you selec t Velocity (the default) in the Vectors of list, the v ectors will b e dr awn based on the absolut e, stationar y reference frame . If you selec t Rela tive Velocity, the v ectors will b e dr awn based on the r eference frame of the Referenc e Zone in the Reference Values Task P age (p.3601 ). See Setting the R eference Zone (p.2954 ) for details . (If you ar e mo deling a single mo ving r eference frame , you need not sp ecify the Referenc e Zone ; the v ectors will b e dr awn based on the mo ving r eference frame .) 40.1.3.3. Vector P lot O ptions The options men tioned in the pr ocedur e ab ove include sc aling the v ector ar rows, skipping the displa y of some v ectors, displa ying v ectors in the plane of the da ta sur face, displa ying fix ed-length or fix ed- color v ectors, displa ying dir ectional c omp onen ts of the v ectors, specifying a r ange of v alues t o be displa yed, color ing the v ectors b y a diff erent scalar field , including p ortions of the mesh in the v ector displa y, and changing the st yle of the ar rows or the sc ale of the ar rowheads . The most c ommon options ar e set in the Vectors D ialog Box (p.3954 ), and others ar e set in the Vector Options D ialog Box (p.3664 ) (Figur e 40.20: The Vector Options D ialog Box (p.2796 )), which y ou c an op en by click ing Vector Options ... in the Vectors D ialog Box (p.3954 ). Figur e 40.20: The Vector Options D ialo g Box 40.1.3.3.1. Scaling the Vectors By default , vectors ar e sc aled aut oma tically so tha t the ar rows overlap minimally when no v ectors are sk ipped. For instr uctions on thinning the v ector displa y, see “Thinning ” Pathlines (p.2806 ).With the Auto Sc ale option, you c an mo dify the Scale factor (which is set t o 1 b y default) t o incr ease or decr ease the v ector sc ale fr om the default “auto sc ale”.The main ad vantage of aut oscaling is tha t the v ector displa y with a sc ale fac tor of 1 will alw ays be appr opriate, regar dless of the siz e of the domain, giving y ou a b etter star ting p oint for fine-tuning the v ector sc ale. If you tur n off the Auto Sc ale option, the v ectors will b e dr awn a t their ac tual siz es sc aled b y the scale fac tor (Scale, which is set t o 1 b y default). The “actual” size of a v ector is the magnitude of the vector v ariable (v elocity, by default) a t the p oint wher e it is dr awn. A v ector dr awn a t a p oint wher e the v elocity magnitude is 100 m/s is dr awn 100 m long , whether the domain is 0.1 m or 1000 m. You Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2796Displa ying G raphicscan mo dify the v ector sc ale b y changing the v alue of Scale in the Vectors D ialog Box (p.3954 ) until the siz e of the v ectors (tha t is, the ac tual siz e multiplied b y Scale) is sa tisfac tory. 40.1.3.3.2. Skipping Vectors If your v ector displa y is difficult t o understand b ecause ther e ar e too man y ar rows displa yed, you can “thin out ” the v ectors b y changing the Skip value in the Vectors D ialog Box (p.3954 ). By default , Skip is set t o 0, indic ating tha t a v ector will b e dr awn f or each c ell in the domain or f or each fac e on the selec ted sur face (for e xample , vectors). If you incr ease Skip to 1, every other v ector will b e displa yed, yielding vectors. If you incr ease Skip to 2, every thir d vector will b e displa yed, yielding vectors, and so on. The or der of fac es on the selec ted sur face (or c ells in the domain) will det ermine which v ectors ar e sk ipped or dr awn; ther efore adaption will change the app earance of the v ector displa y when a nonz ero Skip value is used . 40.1.3.3.3. Drawing Vectors in the P lane of the S urface For some pr oblems , you ma y be in terested in visualizing v elocity (or other v ector) c omp onen ts tha t are nor mal t o the flo w.These “secondar y flo w” comp onen ts ar e usually much smaller than the comp onen ts in the flo w dir ection and ar e difficult t o see when the flo w dir ection c omp onen ts ar e also visible .To easily view the nor mal flo w comp onen ts, you c an enable the In P lane option in the Vector Options D ialog Box (p.3664 ).When this option is on, ANSY S Fluen t will displa y only the v ector comp onen ts in the plane of the sur face selec ted f or displa y. If the selec ted sur face is a cr oss-sec tion of the flo w domain, you will b e displa ying the c omp onen ts nor mal t o the flo w. Figur e 40.21: Velocity Vectors G ener ated U sing the In P lane Option (p.2797 ) sho ws velocity vectors gener ated using the In P lane option. Note tha t these v ectors ha ve been tr ansla ted outside the do- main, as descr ibed in Transf orming G eometr ic O bjec ts in a Sc ene (p.2852 ), so tha t the y can b e seen mor e easily . Figur e 40.21: Velocity Vectors G ener ated U sing the In P lane Option 2797Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Basic G raphics G ener ation40.1.3.3.4. Displa ying F ixed-L ength Vectors By default , the length of a v ector is pr oportional t o its v elocity magnitude . If you w ant all of the vectors t o be displa yed with the same length, you c an enable the Fixed L ength option in the Vector Options D ialog Box (p.3664 ).To mo dify the v ector length, adjust the v alue of the Scale factor in the Vectors D ialog Box (p.3954 ). 40.1.3.3.5. Displa ying Vector C omp onents All Cartesian c omp onen ts of the v ectors ar e dr awn b y default , so tha t the ar row p oints along the resultan t vector in ph ysical spac e. However, sometimes one of the c omp onen ts, say, the comp onen t, is relatively lar ge. In such c ases , you ma y want to suppr ess the comp onen t and sc ale up the v ectors, in or der t o visualiz e the smaller and comp onen ts.To suppr ess one or mor e of the v ector c om- ponen ts, turn off the appr opriate butt on(s) ( X,Y, or Z Comp onen t) in the Vector Options D ialog Box (p.3664 ). 40.1.3.3.6. Specifying the R ange of M agnitudes D ispla yed By default , the minimum and maximum v ectors included in the v ector displa y are set based on the range of v ector-v ariable (v elocity, by default) magnitudes in the en tire domain. If you w ant to focus in on a smaller r ange of v alues , you c an r estrict the r ange t o be displa yed.The c olor sc ale f or the vector displa y will change t o reflec t the new r ange of v alues . (You c an also use the minimum and maximum v alues on the selec ted sur faces—r ather than on the en tire domain—t o det ermine the range , or change the sc alar field b y which the v ectors ar e color ed fr om v elocity magnitude t o an y other sc alar, as descr ibed b elow.) To manually set the r ange of v elocity magnitudes (or the r ange of wha tever sc alar field is selec ted in the Color b y drop-do wn list), turn off the Auto Range option in the Vectors D ialog Box (p.3954 ). The Min and Max fields will b ecome editable , and y ou c an en ter the new r ange of v alues t o be displa yed. For e xample , if y ou w ant to displa y velocity vectors only in r egions wher e the v elocity magnitude e xceeds 150 m/s but is less than 300 m/s , you will change the v alue of Min to 150 and the v alue of Max to 300. Similar ly, if y ou ar e color ing the v ectors b y sta tic pr essur e, you c an cho ose to displa y velocity vectors only in r egions wher e the pr essur e is within a sp ecified r ange .To sho w the default r ange a t an y time , click Comput e and the Min and Max fields will b e up dated. When y ou r estrict the r ange of v ectors displa yed, you c an also c ontrol whether or not v alues outside the pr escr ibed Min/ Max range ar e displa yed.To lea ve ar eas in which the v alue is outside the sp ecified range empt y (tha t is, draw no v ectors), enable the Clip t o Range option. This is the default setting . If you tur n Clip t o Range off, values b elow the Min value will b e color ed with the lo west c olor on the c olor sc ale, and v alues ab ove the Max value will b e color ed with the highest c olor on the c olor scale.This f eature is the same as the one a vailable f or displa ying filled c ontours (see Figur e 40.16: Filled Contours with C lip t o Range On (p.2790 ) and Figur e 40.17: Filled C ontours with C lip t o Range Off (p.2790 )). You c an also cho ose t o base the minimum and maximum v alues on the r ange of v alues on the se- lected sur faces, rather than the en tire domain. To do this , turn off the Global R ange option in the Vectors D ialog Box (p.3954 ).The Min and Max values will b e up dated when y ou ne xt click Comput e or Displa y. 40.1.3.3.7. Changing the Sc alar F ield Used for C oloring the Vectors If you w ant to color the v ectors b y a sc alar field other than v elocity magnitude (the default), you can selec t a diff erent variable or func tion in the Color b y drop-do wn list. Selec t the desir ed c ategor y Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2798Displa ying G raphicsin the upp er list , and then cho ose one of the r elated quan tities fr om the lo wer list. If you cho ose static pr essur e, for e xample , the length of the v ectors will still c orrespond t o the v elocity magnitude , but the c olor of the v ectors will c orrespond t o the v alue of pr essur e at each p oint wher e a v ector is dr awn. 40.1.3.3.8. Displa ying Vectors Using a S ingle C olor If you w ant all of the v ectors t o be the same c olor , you c an selec t the c olor t o be used in the Color drop-do wn list in the Vector Options D ialog Box (p.3664 ). If no c olor is selec ted (tha t is, if y ou cho ose the empt y spac e at the t op of the dr op-do wn list—the default selec tion), the v ector c olor will b e determined b y the Color b y field sp ecified in the Vectors D ialog Box (p.3954 ). Single c olor v ectors are useful in displa ys tha t overlay contours and v ectors. 40.1.3.3.9. Including the Mesh in the Vector P lot For some pr oblems , esp ecially c omple x 3D geometr ies, you ma y want to include p ortions of the mesh in y our v ector plot as spa tial r eference points. For e xample , you ma y want to sho w the lo cation of an inlet and an outlet along with the v ectors.This is acc omplished b y tur ning on the Draw M esh option in the Vectors D ialog Box (p.3954 ).The Mesh D ispla y Dialog Box (p.3239 ) will app ear aut oma t- ically when y ou enable the Draw M esh option, and y ou c an set the mesh displa y par amet ers ther e. When y ou click Displa y in the Vectors D ialog Box (p.3954 ), the mesh displa y, as defined in the Mesh Displa y Dialog Box (p.3239 ), will b e included in the v ector plot. Note The Draw M esh option settings ar e not sa ved with the v ector plot definition. Onc e the dialo g box is closed these settings will r evert to being disabled . To include the mesh with a v ector plot tha t will b e persist ed with the c ase file , you c an create a mesh plot definition and include b oth the mesh and v ector plots in a sc ene. See Displa ying a Sc ene (p.2812 ) for mor e details . 40.1.3.3.10. Changing the A rrow C har acteristics There ar e se ven diff erent vector ar row st yles a vailable . Choose 3d ar row,3d ar rowhead ,cone , filled-ar row,arrow,harpoon, or headless in the Style drop-do wn list in the Vectors D ialog Box (p.3954 ). If you cho ose a v ector ar row st yle tha t includes heads , you c an c ontrol the siz e of the ar rowhead by mo difying the Scale H ead value in the Vector Options D ialog Box (p.3664 ). 40.1.3.4. Creating and M anaging C ustom Vectors In addition t o the v elocity vector quan tity pr ovided b y ANSY S Fluen t, you c an also define y our o wn cust om v ectors t o be plott ed.This c apabilit y is a vailable with the Custom Vectors D ialog Box (p.3664 ). Any cust om v ectors tha t you define will b e sa ved in the c ase file the ne xt time tha t you sa ve it. You can also sa ve your cust om v ectors t o a separ ate file , so tha t the y can b e used with a diff erent case file. 2799Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Basic G raphics G ener ation40.1.3.4.1. Creating C ustom Vectors To cr eate your o wn cust om v ector, you will use the Custom Vectors D ialog Box (p.3664 ) (Fig- ure 40.22: The C ustom Vectors D ialog Box (p.2800 )).This dialo g box enables y ou t o define cust om vectors based on e xisting quan tities . Any vectors tha t you define will b e added t o the Vectors of list in the Vectors D ialog Box (p.3954 ). To op en the Custom Vectors D ialog Box (p.3664 ), click Custom Vectors... in the Vectors D ialog Box (p.3954 ). Figur e 40.22: The C ustom Vectors D ialo g Box The st eps f or cr eating a cust om v ector ar e as f ollows: 1. Specify the name of the cust om v ector in the Vector N ame field . Imp ortant Do not sp ecify a name tha t is alr eady used f or a standar d vector (f or e xample ,velo- city or relative-velocity ). 2. Selec t the v ariable or func tion f or the x comp onen t of the v ector in the X Comp onen t drop-do wn list. First selec t the desir ed c ategor y in the upp er list; you ma y then selec t a r elated quan tity in the lo wer list. For an e xplana tion of the v ariables in the list , see Field F unction D efinitions (p.2959 ). 3. Repeat the st ep ab ove to selec t the v ariable or func tion f or the comp onen t (and , in 3D , the com- ponen t) of the cust om v ector. Imp ortant You c an use the Custom Vectors option t o plot v ectors in solid c ell z ones .The scalars tha t are selec ted in the x,y (and , in 3D , the z) comp onen ts, and tha t are valid in solid r egions , will ha ve vector plots displa yed in the solid c ell z ones . Note tha t if a vector has no v alid c omp onen ts in the solid r egion, then tha t vector will not b e plott ed in the solid r egion. However, if a t least one c omp onen t of the v ector is v alid in the solid r egion, then only tha t comp onen t of the v ector will b e plott ed. 4. Click Define . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2800Displa ying G raphics40.1.3.4.2. Manipulating , Saving , and L oading C ustom Vectors Onc e you ha ve defined y our v ectors, you c an manipula te them using the Vector D efinitions D ialog Box (p.3665 ) (Figur e 40.23: The Vector D efinitions D ialog Box (p.2801 )).You c an displa y a v ector definition to be sur e tha t it is c orrect, delet e the v ector if y ou decide tha t it is inc orrect and must b e redefined , or giv e the v ector a new name .You c an also sa ve cust om v ectors t o a file or r ead them fr om a file . The cust om v ector file enables y ou t o transf er cust om v ectors b etween c ase files . To op en the Vector D efinitions D ialog Box (p.3665 ), click Manage ... in the Custom Vectors D ialog Box (p.3664 ). Figur e 40.23: The Vector D efinitions D ialo g Box The f ollowing ac tions c an b e performed in the Vector D efinitions D ialog Box (p.3665 ): •To check the definition of a v ector, selec t it in the Vectors list. Its definition will b e displa yed in the X Comp onen t,Y Comp onen t, and Z Comp onen t fields a t the t op of the dialo g box.This displa y is f or in- formational pur poses only ; you c annot edit it. If you w ant to change a v ector definition, you must delet e the v ector and define it again in the Custom Vectors D ialog Box (p.3664 ). •To delet e a v ector, selec t it in the Vectors list and click Delet e. •To rename a v ector, selec t it in the Vectors list, enter a new name in the Name field , and click Rename . Imp ortant Do not sp ecify a name tha t is alr eady used f or a standar d vector (f or e xample ,velo- city or relative-velocity ). 2801Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Basic G raphics G ener ation•To sa ve all the v ectors in the Vectors list t o a file , click Save... and sp ecify the file name in The S elec t File Dialog Box (p.569). •To read cust om v ectors fr om a file tha t you sa ved as descr ibed ab ove, click Load and sp ecify the file name in The S elec t File D ialog Box (p.569). (Custom v ectors ar e valid Scheme func tions , and c an also b e loaded with the File/Read/Scheme ... ribbon tab it em, as descr ibed in Reading Scheme S ource Files (p.597).) 40.1.3.5. Creating and Using Vector P lot D efinitions You c an cr eate named v ector plot definitions and sa ve them f or la ter use . See Creating and U sing Contour P lot D efinitions (p.2792 ) for additional inf ormation on plot definitions . The st eps f or cr eating and using v ector plot definitions ar e similar t o the st eps f or Gener ating Vector Plots (p.2794 ), with the addition of a field f or naming the v ector plot definition. Note You c an mo ve the c olor map of a v ector plot definition b y lef t-click ing and dr agging it t o the desir ed lo cation. The c olor map c an also b e resized b y dr agging the c orners of the b ox that app ears when y ou ho ver o ver the c olor map .The c olormap lo cation is not sa ved with the v ector plot definition. 40.1.4. Displa ying P athlines Pathlines ar e used t o visualiz e the flo w of massless par ticles in the pr oblem domain. The par ticles ar e released fr om one or mor e sur faces tha t you ha ve created b y click ing Create in the Surface group box of the Domain ribbon tab (see Creating Sur faces and C ell R egist ers f or D ispla ying and R eporting Data (p.2727 )). A line or rake sur face (see Line and R ake Sur faces (p.2738 )) is most c ommonly used .Fig- ure 40.24: Pathline P lot (p.2803 ) sho ws a sample plot of pa thlines . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2802Displa ying G raphicsFigur e 40.24: Pathline P lot Note tha t the displa y of discr ete-phase par ticle tr ajec tories is discussed in Displa ying of Trajec tor- ies (p.2028 ). 40.1.4.1. Steps for G ener ating P athlines You c an plot pa thlines using the Pathlines D ialog Box (p.3891 ) (Figur e 40.25: The P athlines D ialog Box (p.2804 )). Results → Graphics → Pathlines Edit... 2803Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Basic G raphics G ener ationFigur e 40.25: The P athlines D ialo g Box The basic st eps f or gener ating pa thlines ar e as f ollows: 1. Selec t the sur face(s) fr om which t o release the par ticles in the Release F rom S urfaces list. 2. (Euler ian M ultiphase mo del only) F rom the Track in P hase drop-do wn list , selec t the phase in which pathlines will b e tracked. If you w ant to track pa thlines in the mix ture of all phases , selec t all-phase . By default , par ticles ar e tracked in the pr imar y phase . 3. Set the st ep siz e and the maximum numb er of st eps.The Step S ize sets the length in terval used f or computing the ne xt position of a par ticle . Note tha t par ticle p ositions ar e alw ays comput ed when particles en ter/lea ve a c ell; even if y ou sp ecify a v ery lar ge st ep siz e, the par ticle p ositions a t the en try/exit of each c ell will still b e comput ed and displa yed.The v alue of Steps sets the maximum numb er of st eps a par ticle c an ad vance. A par ticle will st op when it has tr aveled this numb er of st eps or when it lea ves the domain. One simple r ule of thumb t o follow when setting these t wo par amet ers is tha t if y ou w ant the par ticles t o ad vance thr ough a domain of length , the Step S ize times the numb er of Steps should be appr oxima tely equal t o . 4. Set an y of the pa thline plot options descr ibed in Options f or P athline P lots (p.2804 ). 5. Click Displa y to dr aw the pa thlines , or click Pulse to anima te the par ticle p ositions .The Pulse butt on will b ecome the Stop ! butt on dur ing the anima tion, and y ou must click Stop ! to stop the pulsing . 40.1.4.2. Options for P athline P lots You c an include the mesh in the pa thline displa y, control the st yle of the pa thlines (including the twisting of r ibbon-st yle pa thlines), and c olor them b y diff erent scalar fields and c ontrol the c olor sc ale. You c an also “thin ” the pa thline displa y, trace the par ticle p ositions in r everse , and dr aw “oil-flo w” Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2804Displa ying G raphicspathlines . If you ar e “pulsing ” the pa thlines , you c an c ontrol the pulse mo de. If you ar e using lar ger time st ep siz e for c alcula tions then y ou c an c ontrol the accur acy of the pa thline b y sp ecifying t oler ance. In addition t o the r egular pa thline displa y, you c an also gener ate an X Y plot of a sp ecified quan tity along the pa thline tr ajec tories. Finally , you c an cho ose no de or c ell v alues f or displa y (or plotting). 40.1.4.2.1. Including the Mesh in the P athline D ispla y For some pr oblems , esp ecially c omple x 3D geometr ies, you ma y want to include p ortions of the mesh in y our pa thline displa y as spa tial r eference points. For e xample , you ma y want to sho w the location of an inlet and an outlet along with the pa thlines (as in Figur e 40.24: Pathline P lot (p.2803 )). This is acc omplished b y tur ning on the Draw M esh option in the Pathlines D ialog Box (p.3891 ).The Mesh D ispla y Dialog Box (p.3239 ) will app ear when y ou enable the Draw M esh option, wher e you can set the mesh displa y par amet ers.When y ou click Displa y in the Pathlines D ialog Box (p.3891 ), the mesh displa y, as defined in the Mesh D ispla y Dialog Box (p.3239 ), will b e included in the plot of pathlines . Note The Draw M esh option settings ar e not sa ved with the pa thline definition. Onc e the dialo g box is closed these settings will r evert to being disabled . If you w ant these settings persist ed within the cur rent session, you c an use the non-p ersist ent Pathlines dialo g box. Results → Graphics → Pathlines → Edit... 40.1.4.2.2. Contr olling the P athline St yle Pathlines c an b e displa yed as lines (with or without ar rows), ribbons, cylinders (c oarse , medium, or fine), triangles , spher es, or a set of p oints.You c an cho ose line ,line-ar rows,point,spher e,ribbon, triangle ,coarse-c ylinder ,medium-c ylinder , or fine-c ylinder in the Style drop-do wn list in the Pathlines D ialog Box (p.3891 ). Pulsing c an b e done only on point,spher e, or line styles . Onc e you ha ve selec ted the pa thline st yle, click Style A ttribut es... to set the pa thline thick ness and other par amet ers r elated t o the selec ted Style: •If you ar e using the line or line-ar rows style, set the Line Width in the Path S tyle A ttribut es D ialog Box (p.3667 ) tha t app ears when y ou click Style A ttribut es.... For line-ar rows you will also set the Spacing Factor, which c ontrols the spacing b etween the lines .The siz e of the ar row heads c an b e adjust ed b y entering a v alue in the Scale text-en try box. •If you ar e using the point style, you will set the Marker S ize in the Path S tyle A ttribut es D ialog Box (p.3667 ). The thick ness of the pa thline will b e the thick ness of the mar ker. •If you ar e using the spher e style, you will set the Diamet er and the Detail in the Path S tyle A ttribut es Dialog Box (p.3667 ). The b est diamet er to use will dep end on the dimensions of the domain, the view , and the par ticle densit y. However, an adequa te star ting p oint would b e a diamet er on the or der of 1/4 of the a v- erage c ell siz e or 1/4 st ep siz e. Units f or the Diamet er field c orrespond t o the mesh dimensional units . The le vel of detail applied t o the gr aphic al render ing of the spher es c an b e controlled using the Detail field in the Path S tyle A ttribut es D ialog Box (p.3667 ).The le vel of detail uses in teger v alues ranging fr om 4 t o 50. Note tha t the p erformanc e of the gr aphic al render ing will b e better when 2805Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Basic G raphics G ener ationusing a small le vel of detail, tha t is, very coarse spher es, such as 6 or 8. The r ender ing p erformanc e signific antly decr eases with higher le vels of detail. You should gr adually incr ease the detail t o determine the b est-c ase sc enar io b etween p erformanc e and qualit y. Also not e tha t to tak e full ad vantage of spher ical render ing, ligh ting should b e tur ned on in the view .The G ouraud setting pr ovides much smo other lo oking spher es than the F lat setting and better p erformanc e than the P hong setting . For mor e inf ormation on ligh ting , see Adding Ligh ts (p.2829 ). •If you ar e using the triangle or an y of the cylinder styles , you will set the Width in the Path S tyle A ttribut es Dialog Box (p.3667 ). For tr iangles , the sp ecified v alue will b e half the width of the tr iangle ’s base , and f or cylinders , the v alue will b e the c ylinder ’s radius . •If you ar e using the ribbon style, click ing Style A ttribut es... opens the Ribbon A ttribut es D ialog Box (p.3667 ), in which y ou c an set the r ibbon’s Width .You c an also sp ecify par amet ers f or twisting the ribbon pa thlines . In the Twist B y drop-do wn list , you c an selec t a sc alar field on which the pa thline twisting is based (f or e xample , helicit y). Selec t the desir ed c ategor y in the upp er list and then selec t a related quan tity in the lo wer list. The t wisting ma y not b e displa yed smo othly b ecause the sc alar field by which y ou ar e twisting the pa thline is c alcula ted a t cell c enters only (and not in terpolated t o a par ticle ’s position). The Twist Sc ale sets the amoun t of t wist f or the selec ted sc alar field .To magnify the t wist f or a field with v ery little change , incr ease this fac tor; to displa y less t wist f or a field with dr ama tic changes , decr ease this fac tor. When y ou click Comput e, the Min and Max fields will b e up dated t o sho w the r ange of the Twist By scalar field . 40.1.4.2.3. Contr olling P athline C olors By default , the pa thlines ar e color ed b y the par ticle ID numb er.That is, each par ticle ’s pa th will b e a diff erent color .You c an also cho ose the c olor based on the sur face from wher e the pa thlines w ere released fr om using the sur face ID as the par ticle v ariable .You c an cho ose t o color the pa thlines b y any of the sc alar fields in the Color b y drop-do wn list. Selec t the desir ed c ategor y in the upp er list and then selec t a r elated quan tity in the lo wer list. If you c olor the pa thlines b y velocity magnitude , for e xample , each par ticle ’s pa th will b e color ed dep ending on the sp eed of the par ticle a t each point in the pa th. The r ange of v alues of the selec ted sc alar field will, by default , be the upp er and lo wer limits of tha t field in the en tire domain. The c olor sc ale will map t o these v alues acc ordingly . If you pr efer to restrict the r ange of the sc alar field , turn off the Auto Range option (under Options ) and set the Min and Max values manually b enea th the Color b y list. If you c olor the pa thlines b y velocity, and y ou limit the r ange t o values b etween 30 and 60 m/s , for e xample , the “lowest” color will b e used when the particle sp eed falls b elow 30 m/s and the “highest ” color will b e used when the par ticle sp eed e xceeds 60 m/s .To sho w the default r ange a t an y time , click Comput e and the Min and Max fields will b e updated. 40.1.4.2.4. “Thinning ” Pathlines If your pa thline plot is difficult t o understand b ecause ther e ar e too man y pa ths displa yed, you c an “thin out ” the pa thlines b y changing the Path S kip value in the Pathlines D ialog Box (p.3891 ). By default ,Path S kip is set t o 0, indic ating tha t a pa thline will b e dr awn fr om each fac e on the selec ted surface (for e xample , pathlines). If you incr ease Path S kip to 1, every other pa thline will b e displa yed, yielding pathlines . If you incr ease Path S kip to 2, every thir d pa thline will b e displa yed, yielding , and so on. The or der of fac es on the selec ted sur face will det ermine which pa thlines ar e sk ipped Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2806Displa ying G raphicsor dr awn; ther efore adaption will change the app earance of the pa thline displa y when a nonz ero Path S kip value is used . 40.1.4.2.5. Coarsening P athlines To fur ther simplify pa thline plots , and r educ e plotting time , a coarsening fac tor c an b e used t o reduc e the numb er of p oints tha t are plott ed. Providing a c oarsening fac tor of , will r esult in each th point being plott ed f or a giv en pa thline in an y cell.This c oarsening fac tor is sp ecified in the Pathlines Dialog Box (p.3891 ), in the Path C oarsen field . For e xample , if the c oarsening fac tor is set t o 2, then ANSY S Fluen t will plot alt ernate points. Imp ortant Note tha t if an y par ticle or pa thline en ters a new c ell, this p oint will alw ays be plott ed. 40.1.4.2.6. Reversing the P athlines If you ar e in terested in det ermining the sour ce of a par ticle f or which y ou k now the final destina tion (for e xample , a par ticle tha t lea ves the domain thr ough an e xit b oundar y), you c an r everse the pathlines and f ollow them fr om their destina tion back t o their sour ce.To do this , enable the Reverse option in the Pathlines D ialog Box (p.3891 ). All other inputs f or defining the pa thlines will b e exactly the same as f or forward pa thlines; the only diff erence is tha t the sur face(s) selec ted in the Release From S urfaces list will b e the final destina tion of the par ticles inst ead of their sour ce. 40.1.4.2.7. Plotting O il-Flow P athlines If you w ant to displa y “oil-flo w” pathlines (tha t is, pathlines tha t are constr ained t o lie on a par ticular boundar y), enable the Oil F low option in the Pathlines D ialog Box (p.3891 ).You will then need t o selec t a single b oundar y zone in the On Z one list. The selec ted z one is the b oundar y on which the oil-flo w pa thlines will lie . 40.1.4.2.8. Contr olling the P ulse Mo de If you ar e going t o use the Pulse butt on in the Pathlines D ialog Box (p.3891 ) to anima te the pa thlines , you c an cho ose one of t wo pulse mo des f or the r elease of par ticles tha t follow the pa thlines .To release a single w ave of par ticles , selec t the Single option under Pulse M ode.To release par ticles c ontinu- ously fr om the initial p ositions , selec t the Continuous option. 40.1.4.2.9. Contr olling the A ccur acy If you ar e using lar ge time st ep siz e for the c alcula tion, ther e migh t be signific ant error in troduced while c alcula ting the pa thlines .To control this er ror, selec t Accur acy Control and sp ecify the v alue of Toler anc e.The t oler ance value will b e tak en in t o consider ation while c alcula ting the pa thlines for each time st ep. 40.1.4.2.10. Plotting R elativ e Pathlines If you w ant to displa y the pa thlines r elative to the mo ving r eference frame , enable the Rela tive Pathlines option in the Pathlines D ialog Box (p.3891 ).You will then need t o selec t the sur faces fr om the Release fr om S urfaces list. 2807Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Basic G raphics G ener ation40.1.4.2.11. Gener ating an X Y Plot A long P athline Trajec tories If you w ant to gener ate an X Y plot along the tr ajec tories of the pa thlines y ou ha ve defined , enable the XY Plot option in the Pathlines D ialog Box (p.3891 ).The Color b y drop-do wn list will b e replac ed by Y A xis F unc tion and X A xis F unc tion lists . Selec t the v ariable t o be plott ed on the -axis in the Y A xis F unc tion list, and sp ecify whether y ou w ant to plot this quan tity as a func tion of the Time elapsed along the tr ajec tory, or the Path L ength along the tr ajec tory by selec ting the appr opriate item in the X A xis F unc tion drop-do wn list. Specify the Step S ize, numb er of Steps, and other paramet ers as usual f or a standar d pa thline displa y.Then click Plot to displa y the X Y plot. Onc e you ha ve gener ated an X Y plot , you ma y want to sa ve the plot da ta to a file .You c an r ead this file in to ANSY S Fluen t at a la ter time and plot it alone using the File X Y Plot D ialog Box (p.3708 ), as descr ibed in XY Plots of F ile D ata (p.2869 ), or add it t o a plot of solution da ta, as descr ibed in In- cluding Ex ternal D ata in the S olution X Y Plot (p.2868 ). To sa ve the plot da ta to a file , enable the Write to File option in the Pathlines D ialog Box (p.3891 ). The Plot butt on changes t o a Write... butt on. Clicking Write... opens The S elec t File D ialog Box (p.569), in which y ou c an sp ecify a name and sa ve a file c ontaining the plot da ta.The f ormat of this file is descr ibed in XY Plot F ile F ormat (p.2874 ). 40.1.4.2.12. Saving P athline D ata To sa ve pa thline da ta to a file , perform the f ollowing st eps: 1. Enable the Write to File option in the Pathlines D ialog Box (p.3891 ) (Figur e 40.25: The P athlines D ialog Box (p.2804 )). 2. In the Type drop-do wn list , selec t one of the f ollowing t ypes of files: •Standar d for FIELDVIEW (.fvp ) format •Geometr y for .ibl format (which c an b e read b y GAMBIT ) •EnSight format Imp ortant If you plan t o wr ite the pa thline da ta in EnSight format, you should first v erify tha t you ha ve alr eady wr itten the files asso ciated with the EnSight Case G old file t ype by using the File/E xport... ribbon tab option (see EnSight Case G old F iles (p.618)). For fur ther inf ormation ab out the files tha t are wr itten f or an y of these t ypes, refer to the appr o- priate sec tion f ollowing these st eps. 3. Choose t o color the pa thlines b y an y of the sc alar fields in the Color b y drop-do wn lists . 4. Selec t the sur face(s) fr om which t o release the par ticles in the Release F rom S urfaces list. 5. If you selec ted EnSight under Type, you will need t o sp ecify the EnSight Encas F ile N ame . Use Browse... to selec t the .encas file tha t was cr eated when y ou e xported the file with the File/E xport... ribbon tab option. If you do not mak e a selec tion, then y ou will need t o create an appr opriate .encas file manually . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2808Displa ying G raphicsYou c an also selec t the numb er of Time S teps F or E nSight Export.This numb er dir ectly de- termines ho w man y time le vels will b e available f or anima tion in EnS ight. 6. Click Write... to op en The S elec t File D ialog Box (p.569), in which y ou c an sp ecify a name and sa ve a file c ontaining the pa thline da ta. To initia te sa ving pa thline da ta thr ough the t ext command in terface en ter the f ollowing TUI c ommand: display/path-lines/write-to-files In addition t o pa thline da ta, you c an also e xport par ticle da ta in either Standar d,EnSight or Geo- metr y type. For inf ormation on e xporting par ticle da ta in FIELD VIEW (standar d),EnSight or .ibl (geometr y) format, refer to Exporting S teady-State Particle Hist ory Data (p.625). 40.1.4.2.12.1. Standar d Type If Standar d is selec ted under Type, ANSY S Fluen t will wr ite the file in FIELD VIEW format, which c an be exported and r ead in to FIELD VIEW.The FIELD VIEW ASCII P article P ath F ormat is lic ensed fr om Intelligen t Ligh t, proprietor of an indep enden t visualiza tion sof tware pack age ( http://www .iligh t.com). The file name tha t you use f or sa ving the da ta must ha ve a .fvp extension. You also ha ve the abilit y to retrieve and displa y the par ticle and pa thline tr ajec tories fr om the file . If the c ase is st eady-sta te, the par ticle pa th inf ormation will b e wr itten in ASCII f ormat. For tr ansien t or unst eady-sta te cases , the BINAR Y format must b e used .The FIELD VIEW file c ontains a set of paths, wher e each pa th c onsists of a ser ies of p oints. At every point the spa tial lo cation and selec ted variables ar e defined . A full descr iption of the ASCII and BINAR Y formats can b e found in A ppendix K - P article P ath F ormats of FIELD VIEW’s Reference M anual [2] (p.4005 ), available t o lic ensed FIELD VIEW users . The f ollowing is an e xample of the FIELD VIEW format for a st eady-sta te case: FVPARTICLES 2 1 Tag Names 0 Variable Names 2 time particle_id 3 0.2 0.8 1.3 0.2 0 0.3 0.9 1.3 0.4 0 0.5 1.1 1.3 0.6 0 The b eginning of the file displa ys header inf ormation.Tag Names cannot b e sp ecified when the file is e xported fr om ANSY S Fluen t, and henc e will alw ays be 0. ANSY S Fluen t enables y ou t o export two variables , which ar e list ed under Variable Names : the first is det ermined b y the sc alar fields selec ted in the Color b y drop-do wn lists (time in the e xample ab ove); the sec ond is alw ays particle_id . The r est of the file c ontains inf ormation ab out each pa th. A pa th sec tion b egins b y listing the t otal numb er of p oints for the pa th.Then a line of da ta is pr esen ted f or each p oint, with the X, Y, and Z locations list ed in the first thr ee c olumns and the v ariable inf ormation in the f ourth and fif th c olumns . The e xample ab ove pr esen ts a single pa thline c onsisting of thr ee p oints; the time r anges fr om .2 to .6, and the ID of the par ticle is 0. 2809Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Basic G raphics G ener ation40.1.4.2.12.2. Geometr y Type If Geometr y is selec ted under Type, the file will b e wr itten in .ibl format.The r esulting file c ontains particle pa ths in the f orm of a cur ve tha t can b e read in GAMBIT .The f ollowing is an e xample of a Geometr y file f ormat tha t contains multiple cur ves: Closed Index Arclength Begin section ! 1 Begin curve ! 1 1 185.61 0 23.26 2 88.90000000000001 0 -89.67 Begin curve ! 2 1 88.89999999999569 0 -89.6699999999997 2 76.90221619148909 0 -101.2290490001453 3 62.92208239159677 0 -110.2907424975297 4 47.47166726362848 0 -116.5231659809653 5 31.11689338997181 0 -119.6980363161113 6 14.45680848476821 0 -119.6990633707006 7 -1.898356710978934 0 -116.5262095254603 8 -17.34954014966171 0 -110.2956910520416 9 -31.33079110697006 0 -101.2357213074894 10 -43.330000000007 0 -89.67815166483965 Begin curve ! 3 1 -43.33 0 -89.67815166485001 2 -175.56 0 64.69066040289 The ab ove example demonstr ates ho w multiple cur ves c an b e imp orted; single cur ves ma y also b e imp orted. After imp orting this file in to GAMBIT , the file is r ead b y first lo oking f or a Begin curve string and then lo oking f or the X, Y, and Z c oordina tes under the Begin curve line . 40.1.4.2.12.3. EnSight Type By selec ting EnSight under Type, you c an gener ate files with the f ollowing e xtensions: •.mpg •.mscl •.encas An .mpg file will b e wr itten f or e very time st ep sp ecified in the Time S teps F or E nSight Export field . A sequen tial numb er will b e app ended t o the .mpg extension t o indic ate the time st ep. Each file c ontains a header tha t lists the time a t which the da ta w as e xported, as w ell as thr ee c olumns listing the X, Y, and Z c oordina tes for e very par ticle a t tha t par ticular time st ep. The f ollowing is an e xample of a file c alled particle.mpg0003 , which c ontains da ta for nine particles a t the thir d time st ep: File is written from fluent in ensight measured particle format for t = 2.42813e-04 particle coordinates 9 1-7.27734e-05 1.91710e-03 4.69093e-03 2-1.75772e-04 1.97040e-03 3.92842e-03 3-2.26051e-04 2.10134e-03 5.63228e-03 4-1.16390e-04 2.32442e-03 5.23423e-03 5-6.32735e-04 2.53326e-03 5.70791e-03 6-9.69431e-04 2.37006e-03 5.27602e-03 7-6.77868e-04 2.92054e-03 4.11570e-03 8-9.78029e-04 2.75717e-03 4.13314e-03 9-8.54859e-04 3.73727e-03 2.23796e-03 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2810Displa ying G raphicsAn .mscl file will b e wr itten f or e very time st ep sp ecified in the Time S teps F or E nSight Export field . A sequen tial numb er will b e app ended t o the .mscl extension t o indic ate the time st ep. Each file c ontains the sc alar inf ormation (sp ecified under Color B y) for e very par ticle a t a par ticular time step. The f ollowing is an e xample of a file c alled particle.mscl0006 , which c aptur es Particle ID data for nine par ticles a t the six th time st ep: particle id 0.00000e+00 6.00000e+00 1.20000e+01 1.80000e+01 2.40000e+01 3.00000e+01 3.60000e+01 4.20000e+01 4.80000e+01 A new .encas file will b e wr itten if a selec tion is made under EnSight Encas F ile N ame .This new file is a mo dified v ersion of the .encas file selec ted with the Browse... butt on, and c ontains inf orm- ation ab out all of the r elated files (including geometr y, velocity, scalar and c oordina te files). The name of the new file will b e the r oot of the or iginal file with .new app ended t o it (f or e xample if test.encas is selec ted, a file named test.new.encas will b e wr itten). It is this new file tha t should b e read in to EnSight. The f ollowing is an e xample of a file c alled spray2-unsteady.new.encas , tha t refers t o the files gener ated when the da ta w as or iginally e xported as an EnSight Case G old file t ype (.geo , .vel ,.sc11 , and .sc12 ) and the files cr eated dur ing the pa thline da ta e xport (.mpg and .mscl ): FORMAT type: ensight gold GEOMETRY model: spray2-unsteady.geo measured: 1 particle.mpg**** VARIABLE scalar per measured node: 1 particle-id particle.mscl**** scalar per node: pressure spray2-unsteady.scl1 scalar per node: pressure-coefficient spray2-unsteady.scl2 vector per node: velocity spray2-unsteady.vel TIME time set: 1 Model number of steps: 10 filename start number: 1 filename increment: 1 time values: 0.00000e+00 1.21406e-04 2.42813e-04 3.64219e-04 4.85626e-04 6.07032e-04 7.28438e-04 8.49845e-04 9.71251e-04 1.09266e-03 40.1.4.2.13. Choosing N ode or C ell Values In ANSY S Fluen t you c an det ermine the sc alar field v alue a t a par ticle lo cation using the c omput ed cell-c enter v alues or v alues tha t ha ve been in terpolated t o the no des. By default , the Node Values option is tur ned on, and the in terpolated v alues ar e used . If you pr efer to use the c ell v alues , turn the Node Values option off . Note tha t for fac e-only func tions lik e Wall S hear S tress, the c ell v alue is the ar ea-w eigh ted a verage fr om the fac e values tha t define tha t cell as c0. If you ar e plotting pa thlines t o sho w the eff ect of a p orous medium or 2D fan b oundar y, to depic t a sho ck w ave, or t o sho w an y other disc ontinuities or jumps in the plott ed v ariable , you should use cell v alues; if y ou use no de v alues in such c ases , the disc ontinuit y will b e smear ed b y the no de a v- eraging f or gr aphics and will not b e sho wn clear ly in the plot. 40.1.4.3. Creating and Using P athline D efinitions You c an cr eate named pa thline definitions and sa ve them f or la ter use . See Creating and U sing C ontour Plot D efinitions (p.2792 ) for additional inf ormation on gr aphics objec t definitions . 2811Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Basic G raphics G ener ationThe st eps f or cr eating and using pa thline definitions ar e similar t o the Steps f or G ener ating P ath- lines (p.2803 ), with the addition of a field f or naming the pa thline definition. Pathline definitions c an b e included in sc enes as long as the XY Plot option is not enabled . Note You c an mo ve the c olor map of a pa thline definition b y lef t-click ing and dr agging it t o the desir ed lo cation. The c olor map c an also b e resized b y dr agging the c orners of the b ox tha t app ears when y ou ho ver o ver the c olor map .The c olormap lo cation is not sa ved with the pathline definition. 40.1.5. Displa ying a Sc ene Scenes c an b e used t o displa y multiple gr aphics plots within a single windo w. For e xample , you c ould overlay contours of pr essur e acr oss a v alve with v elocity vectors and the mesh a t the same lo cation. Scenes allo w you t o mo dify the tr anspar ency of each plot so tha t you c an emphasiz e a par ticular plot or view . 40.1.5.1. Gener ating a Sc ene You c an plot a sc ene made up of multiple gr aphics objec ts using the Figur e 40.26: The Sc ene D ialog Box (p.2812 ). Results → Scene New... Figur e 40.26: The Sc ene D ialo g Box Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2812Displa ying G raphicsThe basic st eps f or cr eating a sc ene: 1.(Optional) En ter a Name for the sc ene. 2.(Optional) En ter a Title for the sc ene, which will app ear in the gr aphics windo w tab wher e the sc ene is displa yed. 3.Selec t the Graphics O bjec ts tha t you w ant to include in the sc ene.If you w ant t o include additional mesh, cont our, vector, or pathline plots in the sc ene , create them fr om the New O bjec t drop-do wn list . Note that pathlines with the XY P lot option enabled ar e not c ompatible with sc enes . 4.(Optional) You c an mo dify the tr anspar ency of the selec ted gr aphics objec ts using the Transpar enc y slider .If the slider is c omplet ely to the r ight the objec t will b e full y transpar ent. 5.Click Save or Save & D ispla y. Scene C olormaps Onc e the sc ene is displa yed, you c an mo ve the c olor maps b y lef t-click and dr ag. Color maps c an also be resized b y dr agging the c orners of the b ox tha t app ears when y ou ho ver o ver the c olor map . Tip You c an sp ecify a diff erent color map sc ale f or each gr aphic objec t to mak e it easier t o determine the v alues tha t correspond t o the displa yed gr adien ts (t o do this , click Color map Options ... in the c orresponding gr aphics objec t dialo g box). 40.1.6. Displa ying Results on a S weep S urface Sweep sur faces c an b e used when y ou w ant to examine the mesh, contours , or v ectors on v arious sections of the domain without e xplicitly cr eating the c orresponding sur faces. For e xample , if y ou w ant to displa y solution r esults f or a 3D c ombustion chamb er, inst ead of cr eating numer ous sur faces a t different cross-sec tions of the domain, you c an use a sw eep sur face to view the v ariation of the flo w and t emp erature thr oughout the chamb er. 40.1.6.1. Steps for G ener ating a P lot Using a S weep S urface You c an plot meshes , contours , or v ectors on a sw eep sur face using the Sweep Sur face Dialog Box (p.3672 ) (Figur e 40.27: The S weep Sur face Dialog Box (p.2814 )). Results → Anima tions → Sweep S urface Edit... 2813Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Basic G raphics G ener ationFigur e 40.27: The S weep S urface D ialo g Box The basic st eps f or gener ating a mesh, contour, or v ector plot using a sw eep sur face ar e as f ollows: 1. Under Sweep A xis, specify the ( X,Y,Z) vector represen ting the axis along which the sur face should b e swept. 2. Click Comput e to up date the Min Value and Max Value to reflec t the e xtents of the domain along the specified axis . 3. Under Displa y Type, specify the t ype of displa y you w ant to see: Mesh,Contours , or Vectors.The first time tha t you selec t Contours or Vectors, ANSY S Fluen t will op en the Contours D ialog Box (p.3790 ) or the Vectors D ialog Box (p.3954 ) so y ou c an mo dify the settings f or the displa y.To mak e subsequen t modific ations t o the displa y settings , click Properties to op en the Contours D ialog Box (p.3790 ) or Vectors Dialog Box (p.3954 ). 4. Move the slider under Value (which indic ates the v alue of x,y, or z) to mo ve the sw eep sur face thr ough the domain along the sp ecified Sweep A xis. ANSY S Fluen t will up date the mesh, contour, or v ector displa y when y ou r elease the slider .You c an also en ter a p osition in the Value field and pr ess Enter to update the displa y. 5. If you w ant to sa ve the cur rently displa yed sw eep sur face so tha t you c an use it f or a diff erent type of plot (f or e xample , a pa thlines plot or an X Y plot) or c ombine it with displa ys on other sur faces, click Create... to op en the Create Sur face Dialog Box (p.3674 ) (Figur e 40.28: The C reate Sur face Dialog Box (p.2815 )). Enter the Surface Name and click OK. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2814Displa ying G raphicsFigur e 40.28: The C reate Surface D ialo g Box The sur face tha t is cr eated is an isosur face based on the mesh c oordina tes; the c ontour or v ector settings ar e not st ored in the sur face. You c an also anima te the sw eep sur face displa y, as descr ibed b elow, rather than mo ving the slide bar y ourself . 40.1.6.2. Animating a S weep S urface Displa y The st eps f or anima ting a sw eep sur face displa y are as f ollows: 1. Specify the Sweep A xis and Displa y Type as descr ibed ab ove. 2. Under Anima tion , enter the Initial Value and Final Value for the anima tion. These v alues c orrespond to the minimum and maximum v alues along the Sweep A xis for which y ou w ant to anima te the displa y. 3. Specify the numb er of Frames you w ant to see in the anima tion. 4. Click Anima te. 40.1.7. Hiding the G raphics Windo w D ispla y There ma y be situa tions wher e displa ying gr aphics on a lo cal machine is not pr actical.Therefore, you may decide t o hide (or disable) the gr aphics displa y windo w. To disable the gr aphics displa y windo w when star ting ANSY S Fluen t from the c ommand line , you c an specify the dr iver as null: fluent -driver null For an ANSY S Fluen t session tha t is alr eady in pr ogress, the gr aphics windo w displa y can b e disabled using the f ollowing t ext command: display → set → rendering-options → driver → null Imp ortant All gr aphics windo ws must b e closed pr ior t o in voking the pr evious t ext command . If the gr aphics windo w displa y is disabled , you c an c ontinue t o sa ve gr aphics using the Save Picture option, as descr ibed in Saving P icture Files (p.645). Note tha t the sp eed a t which the gr aphics ar e sa ved may be signific antly slo wer with the dr iver set t o null, and the sa ved gr aphics files ma y not b e iden tical to those sa ved when the gr aphics windo w displa y is enabled . 2815Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Basic G raphics G ener ationFor an ANSY S Fluen t session tha t is alr eady in pr ogress, perform the f ollowing st eps t o re-enable a graphics windo w displa y tha t had b een pr eviously disabled: 1. Enter the f ollowing t ext command: display → set → rendering-options → driver 2. Press the Enter key at the driver> prompt t o displa y the a vailable dr ivers. 3. Enter an appr opriate dr iver, such as opengl . If an y gr aphics windo ws are op en (which ar e not visible t o you), ANSY S Fluen t will pr ompt y ou t o close all op en windo ws.You c an close them using the f ollowing Scheme c ommand: (close-all-open-windows) and then r etype the t ext command t o enable the gr aphics windo ws. Imp ortant If you happ en t o be lo gged on t o a machine r emot ely, then some dr ivers ma y not w ork on your sy stem. Use x11 (for Linux) or msw (for Windo ws) inst ead t o enable y our gr aphics windo ws. 40.2. Customizing the G raphics D ispla y There ar e a numb er of w ays in which y ou c an alt er the gr aphic al displa y onc e you ha ve gener ated the basic elemen ts in it (c ontours , meshes , and so on). For e xample , you c an o verlay multiple gr aphics , add descr iptiv e text or ligh ting t o the plot , and mo dify the c aptions or legend la yout. These and other cus- tomiza tions ar e descr ibed in this sec tion. 40.2.1. Advanced G raphics O verlays 40.2.2. Opening M ultiple G raphics Windo ws 40.2.3. Changing the L egend D ispla y 40.2.4. Adding Text to the G raphics Windo w 40.2.5. Changing the C olor map 40.2.6. Adding Ligh ts 40.2.7. Modifying the R ender ing Options Imp ortant It is p ossible tha t the gr aphics windo w ma y become [Out of D ate] (which w ould b e indic ated at the t op of the gr aphics windo w), if y ou mak e changes t o items tha t are alr eady displa yed. To resolv e this out of da te sta te, right-click in the gr aphics windo w and click Refr esh D ispla y in the c ontext menu tha t app ears . If a c ont ext menu do es not app ear on a r ight-click of the gr aphics windo w, ensur e that the r ight- mouse butt on is set t o an ac tion other than mouse-z oom or mouse-pr obe and long description (Vie w ribbon tab ,Mouse group b ox). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2816Displa ying G raphics40.2.1. Advanc ed G raphics O verlays Normally , you c an see only one pic ture at a time in the gr aphics windo w, unless y ou ar e Displa ying a Scene (p.2812 ). Sometimes , however, you ma y want to cr eate an "e xplo ded" view , wher e results tr ansla ted or rotated out f or the ph ysical domain f or enhanc ed displa y (see Figur e 40.29: Explo ded Sc ene D ispla y of Temp erature and Velocity (p.2818 )).You c an do this b y tur ning on the Overlays option (and click ing Apply ) and using the tr ansf orm op eration in the Scene D escr iption D ialog Box (p.3683 ). View → Graphics → Comp ose ... Onc e overlaying is enabled , subsequen t graphics tha t you gener ate will b e displa yed on t op of the existing displa y in the ac tive gr aphics windo w.To gener ate a plot without o verlays, you must tur n off the Overlays option in the Scene D escr iption D ialog Box (p.3683 ) (and r ememb er to click Apply ). When y ou ar e overlaying multiple gr aphics , the c aptions and c olor sc ale tha t will app ear in the la test displa y are those tha t correspond t o the most r ecently dr awn gr aphic . Note tha t when o verlaying is enabled , it will apply t o all gr aphics windo ws, including those tha t are not y et op en.Turning o verlays on and off do es so f or all gr aphics windo ws, not just f or the ac tive windo w.That is, if y ou enable o verlays, open a new gr aphics windo w (as descr ibed in Opening M ultiple Graphics Windo ws (p.2818 )), and then gener ate two or mor e gr aphics in tha t windo w, the y will b e overlaid. 2817Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Customizing the G raphics D ispla yFigur e 40.29: Explo ded Sc ene D ispla y of Temp erature and Velocity 40.2.2. Op ening M ultiple G raphics Windo ws During y our ANSY S Fluen t session, you c an op en up t o 20 gr aphics windo ws at one time and the y may be view ed within the applic ation windo w or in separ ate windo ws.The windo ws are numb ered 1 through 20 and the ID numb er for each windo w will app ear a t the t op of the fr ame tha t sur rounds it. You c an view a sp ecific windo w b y selec ting it fr om the dr op-do wn list ne xt to the ID numb er.The first time y ou displa y gr aphics , windo w 1 will b e displa yed aut oma tically.To op en an additional windo w, you c an use the Displa y Options D ialog Box (p.3681 ) (Figur e 40.30: The D ispla y Options D ialog Box (p.2819 )). Results → Graphics Options ... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2818Displa ying G raphicsFigur e 40.30: The D ispla y Options D ialo g Box Use the up ar row to incr emen t the windo w ID in the Active Windo w field under Graphics Windo w and then click Open.The Close butt on changes t o the Open butt on if the Active Windo w is set t o mor e than 1. To close an op en windo w, incr ease or decr ease the Active Windo w value t o the ID of the windo w to be closed , and then click Close tha t app ears ne xt to the Active Windo w field .The Open butt on changes t o a Close butt on if the Active Windo w is op en. 40.2.2.1. Setting the A ctive Windo w When y ou ha ve mor e than one gr aphics windo w op en, you must iden tify the ac tive windo w so tha t ANSY S Fluen t will k now which one t o dr aw the plot in. There ar e two ways to set the ac tive windo w: you c an simply click an y mouse butt on in the desir ed gr aphics windo w, or y ou c an sp ecify the ID f or the desir ed gr aphics windo w in the Active Windo w field (in the Displa y Options D ialog Box (p.3681 )) and click Set. Regar dless of the metho d used , this windo w will r emain ac tive un til you set a new active windo w. 40.2.3. Changing the L egend D ispla y ANSY S Fluen t graphics include , by default , a caption or legend blo ck tha t consists of fields of t ext de- scribing the c ontents of the gr aphic , the ANSY S Fluen t produc t iden tification, an axis tr iad indic ating the or ientation of the displa yed objec t, a color k ey defining the c orrespondenc e between each c olor and the magnitude of the plott ed v ariable , and the ANSY S logo.You c an tur n off the displa y of the 2819Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Customizing the G raphics D ispla ylegend and c olor sc ale, and/or the axis tr iad.You c an also hide the ANSY S logo.You c an also displa y the c olor map on an y side of the displa y windo w as p er convenienc e. In addition y ou c an also edit the captions dir ectly in the gr aphics windo w. 40.2.3.1. Contr olling the Titles , Axes, Ruler , Logo, and C olormap You c an enable/disable the displa y of the Titles ,Axes, and Ruler directly in the gr aphics windo w b y toggling the appr opriate icon (r efer to Additional D ispla y Options (p.559) for mor e inf ormation). The Logo and the Color map are controlled under Layout in the Displa y Options D ialog Box (p.3681 ) (Fig- ure 40.30: The D ispla y Options D ialog Box (p.2819 )). Results → Graphics Options ... Use the t ext interface to enable/disable the c aptions and c olor sc ale individually , and t o change the size and p osition of the c aptions and c olor sc ale. display → set → windows → text → display → set → windows → scale → See the separ ate Text Command List for details . Contr olling Titles You c an add t ext, such as y our c ompan y name , to the title b ox in multiple lo cations using the dis- play/set/titles/ text command lo cations . Onc e you ha ve pr ovided t ext for one of these lo cations , you must ensur e tha t display/set/windows/text/company? is set t o yes, then r e-render the displa y by displa ying a gr aphics objec t (for e xample , mesh, contour, vector, and so on) or b y en tering display/re-render in the c onsole . Alternatively, if y ou alw ays want your c ompan y name or other t ext displa yed in the title b ox, you c an set the FLUENT_COMPANY environmen t variable in the F luen t Launcher equal t o your c ompan y name or the desir ed t ext, for e xample ,FLUENT_COMPANY=My Example Company Name .Note that Titles is disabled b y default when y ou launch F luent , so y ou will ha ve to enable Titles before it will be displa yed in the gr aphics windo w. 40.2.3.2. Editing the L egend When c aptions ar e displa yed in the gr aphics windo w, you ma y cho ose t o mo dify, delet e, or add t o the t ext tha t app ears in the c aption b ox.To do so , click the lef t mouse butt on in the desir ed lo cation. A cursor will app ear, and y ou c an then t ype new t ext or delet e the t ext tha t was or iginally ther e (using the backspac e or delet e key). Note tha t changes t o existing t ext in the c aption blo ck will b e remo ved when y ou dr aw new gr aphics in the windo w (unless y ou ar e overlaying multiple gr aphics in the same windo w), but t ext tha t you add on a pr eviously empt y line in the c aption blo ck will not b e remo ved until the default c aption t ext mak es use of tha t line . 40.2.3.3. Adding a Title t o the C aption You c an define a title f or y our pr oblem using the title text command: display → set → title Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2820Displa ying G raphicsThe title y ou define will app ear on the t op line of the c aption, at the far lef t, in all subsequen t plots . It will also b e sa ved in the c ase file . Imp ortant You will need t o enclose y our title in quota tion mar ks (f or e xample ," my title "). 40.2.3.4. Enabling/D isabling the A xes You c an disable the displa y of the axis tr iad b y tur ning off the Axes Visibilit y butt on ( ) in the graphics windo w. 40.2.3.5. Enabling/D isabling the R uler You c an disable the displa y of the r uler b y tur ning off the Ruler Visibilit y butt on ( ) in the graphics windo w. Note tha t if y our pr ojec t is 3D , then enabling the r uler aut oma tically changes the view t o or thographic so tha t the r uler mar kings ar e relevant for the mo del. 40.2.3.6. Mo difying and D ispla ying/Hiding the L ogo The gr aphics windo w displa ys a whit e ANSY S logo in the upp er right corner.You ma y cho ose b etween a whit e (default) or black lo go b y selec ting White or Black from the Color drop-do wn list under Layout in the Displa y Options D ialog Box (p.3681 ) (Figur e 40.30: The D ispla y Options D ialog Box (p.2819 )). You c an pr event the ANSY S logo fr om b eing displa yed in the gr aphics windo w b y disabling the Logo option under Layout. 40.2.3.7. Colormap A lignment You c an set the p osition of the c olor map on an y side (lef t, top, bottom, or r ight) of the displa y windo w. Default alignmen t for the c olor map is set t o the Left. If you w ant to change the alignmen t, selec t the requir ed dir ection in the Color map A lignmen t drop-do wn list. 40.2.4. Adding Text to the G raphics Windo w You c an use the Annota te Dialog Box (p.3700 ) to add t ext to the gr aphics windo w with optional a ttach- men t lines .Figur e 40.31: Graphics Windo w with Text Annota tion (p.2822 ) sho ws an e xample of a graphics displa y with annota ted t ext in it. 2821Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Customizing the G raphics D ispla yFigur e 40.31: Graphics Windo w with Text Annota tion 40.2.4.1. Adding Text Using the A nnotat e Dialo g Box Adding t ext to the gr aphics windo w using the Annota te Dialog Box (p.3700 ) (Figur e 40.32: The A nnota te Dialog Box (p.2822 )) enables y ou t o control the f ont and c olor of the t ext. Results → Graphics Annota te... Figur e 40.32: The A nnota te D ialo g Box The st eps f or adding t ext are as f ollows: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2822Displa ying G raphics1. Under Font Specific ation , selec t the f ont type in the Name drop-do wn list , the f ont weigh t (Medium or Bold) in the Weigh t drop-do wn list , the siz e (in p oints) in the Size drop-do wn list , the c olor in the Color drop-do wn list , and the slan t (Regular or Italic ) in the Slant drop-do wn list. 2. Enter the t ext tha t you w ant to add in the Annota tion Text field . 3. Click Add.You will b e ask ed t o pick the lo cation in the gr aphics windo w wher e you w ant to plac e the text, using the mouse-pr obe butt on. By default , the mouse-pr obe butt on is the r ight butt on, but y ou can change this in the Mouse group b ox of the View tab , as descr ibed in Controlling the M ouse B utton Functions (p.2833 ). If you click the mouse butt on onc e in the desir ed lo cation, the t ext will b e plac ed a t tha t point. Dragging the mouse with the mouse-pr obe butt on depr essed will dr aw an a ttachmen t line fr om the p oint wher e the mouse w as first click ed t o the p oint wher e it w as released .The annota tion text will b e plac ed a t the p oint wher e the mouse butt on w as released . 40.2.4.2. Editing E xisting A nnotation Text Onc e you ha ve added t ext to the gr aphics displa y, you ma y change the f ont char acteristics of one or mor e text items , or delet e individual t ext items . To mo dify or delet e existing t ext, follow these st eps: 1. Selec t the appr opriate item in the Names list in the Annota te Dialog Box (p.3700 ) (Figur e 40.32: The A n- nota te Dialog Box (p.2822 )).When y ou selec t a name , the asso ciated t ext will b e displa yed in the Annota- tion Text field , and the Add butt on b ecomes the Edit butt on. 2. Modify the Font Specific ation entries as desir ed, and click Edit to mo dify the t ext, or simply click Delet e Text below the Names list t o delet e the selec ted t ext. Note tha t if y ou w ant to mak e changes t o all cur rent annota tion t ext, you c an selec t all of the Names instead of just one in st ep 1. You c an mo ve the t ext in the same w ay tha t you mo ve other geometr ic objec ts in the displa y, using the Scene D escr iption D ialog Box (p.3683 ) and the Transf ormations D ialog Box (p.3687 ). See Transf orming Geometr ic O bjec ts in a Sc ene (p.2852 ) for details . 40.2.4.3. Clearing A nnotation Text Annota tion t ext is asso ciated with the ac tive gr aphics windo w and is r emo ved only when the annota- tions ar e explicitly clear ed.To remo ve the annota tions fr om the gr aphics windo w, you must click Clear in the Annota te Dialog Box (p.3700 ). If you dr aw new gr aphics in the windo w without clear ing the annota tions , the y will r emain visible in the new displa y. 40.2.5. Changing the C olor map The default c olor map used b y ANSY S Fluen t to displa y gr aphic al da ta (f or e xample , vectors) r anges from blue (minimum v alue) t o red (maximum v alue). Additional pr edefined c olor maps ar e available , and y ou c an also cr eate cust om c olor maps .To mak e an y changes t o the c olor map , you will use the Color map D ialog Box (p.3697 ) (Figur e 40.33: The C olor map D ialog Box (p.2824 )). Results → Graphics Color map ... 2823Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Customizing the G raphics D ispla yFigur e 40.33: The C olor map D ialo g Box When y ou plot c ontours , you c an t emp orarily mo dify the numb er of c olors in the c olor map b y changing the numb er of c ontour le vels in the Contours D ialog Box (p.3790 ); you will only need t o use the Color map Dialog Box (p.3697 ) if y ou w ant to change other char acteristics of the c olor map . Imp ortant Note tha t if y ou ar e using a gr ay-sc ale c olor map and y ou w ant to sa ve a gr ay-sc ale pic ture, you should sa ve a c olor pic ture.When y ou sa ve a gr ay-sc ale pic ture, ANSY S Fluen t uses an internal gr ay sc ale, not the gr ay sc ale sp ecified b y the c olor map . If you sa ve a c olor pic ture, the c olor map y ou selec ted (tha t is, your gr ay sc ale) will b e used . 40.2.5.1. Predefined C olormaps The f ollowing c olor maps ar e aut oma tically a vailable in ANSY S Fluen t: bgr: Blue r epresen ts the minimum v alue , green the middle , and r ed the maximum v alue . Colors in b etween are interpolated fr om blue t o gr een, and fr om gr een t o red. (This is the default c olor map .) bgrb: Blue r epresen ts the minimum and maximum v alues , and gr een and r ed ar e values 1/3 and 2/3 of the maximum v alue , respectively. Colors in b etween ar e interpolated fr om blue t o gr een, from gr een t o red, and fr om r ed t o blue . blue: The minimum v alue is r epresen ted b y blue-black, and the maximum v alue b y pur e blue . cyan-y ello w: Cyan r epresen ts the minimum v alue and y ellow represen ts the maximum v alue . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2824Displa ying G raphicsfea: Blue r epresen ts the minimum v alue and r ed r epresen ts the maximum v alue .The c olors in b etween ar e those used in thir d-par ty finit e elemen t analy sis pack ages . gray: Black is used f or the minimum v alue and whit e for the maximum v alue . green: The minimum v alue is r epresen ted b y gr een-black, and the maximum v alue b y pur e gr een. pur ple-magen ta: Purple r epresen ts the minimum v alue and magen ta represen ts the maximum v alue . red: The minimum v alue is r epresen ted b y red-black, and the maximum v alue b y pur e red. rgb: Red r epresen ts the minimum v alue , green the middle , and blue the maximum v alue . Colors in b etween are interpolated fr om r ed t o gr een, and fr om gr een t o blue . The numb er of c olors in terpolated b etween the c olors in the sc ale name (f or e xample , between pur ple and magen ta) will dep end on the siz e of the c olor map . 40.2.5.2. Selec ting a C olormap The pr ocedur e for selec ting a new c olor map t o be used in gr aphics displa ys is as f ollows: 1. In the Color map D ialog Box (p.3697 ) (Figur e 40.33: The C olor map D ialog Box (p.2824 )), selec t the desir ed color map in the Currently D efined drop-do wn list. This list will c ontain all of the c olor maps pr edefined by ANSY S Fluen t as w ell as an y cust om c olor maps tha t you ha ve created as descr ibed in Creating a Customiz ed C olor map (p.2827 ). 2. Set the c olor map siz e and sc ale as descr ibed in Specifying the C olor map S ize and Sc ale (p.2825 ). 3. Click Apply to up date the cur rent graphics displa y with the new c olor map . All futur e displa ys will use the newly selec ted c olor map and options . 40.2.5.2.1. Specifying the C olormap S ize and Sc ale Onc e you ha ve selec ted the desir ed c olor map fr om the Currently D efined list, you ma y mo dify the Color map S ize.This v alue is the numb er of distinc t colors in the c olor sc ale. You c an also cho ose t o use a lo garithmic sc ale inst ead of a decimal sc ale b y tur ning on the Log Scale option. With a lo g sc ale, the c olor used in the gr aphics displa y will r epresen t the lo g of the value a t tha t location in the domain. The v alues r epresen ted b y the c olors will, ther efore, incr ease exponen tially . 40.2.5.2.2. Changing the Numb er F ormat You c an change the f ormat of the lab els tha t define the c olor divisions a t the lef t of the gr aphics windo w using the c ontrols under the Numb er F ormat heading in the Color map D ialog Box (p.3697 ). 2825Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Customizing the G raphics D ispla y•To displa y the r eal v alue with an in tegral and fr actional par t (for e xample , 1.0000), selec t floa t in the Type drop-do wn list. You c an set the numb er of digits in the fr actional par t by changing the v alue of Precision . •To displa y the r eal v alue with a man tissa and e xponen t (for e xample , 1.0e-02), selec t exponen tial in the Type drop-do wn list. You c an define the numb er of digits in the fr actional par t of the man tissa in the Precision field . •To displa y the r eal v alue with either floa t or e xponen tial f orm, dep ending on the siz e of the numb er and the defined Precision , cho ose gener al in the Type drop-do wn list. 40.2.5.3. Displa ying C olormap L abel You c an cust omiz e the numb er of v alues displa yed on the c olor map .The default numb er of lab els that app ear alongside the c olor map dep ends on the f ont siz e and the c olor map siz e (Figur e 40.34: The Default C olor map Lab el D ispla y (p.2826 )). •To reduc e the numb er of lab els tha t app ear alongside the c olor map , incr ease the numb er of lab els skipped.To do so , deselec t Show A ll in the Color map D ialog Box (p.3697 ) and set the numb er of lab els to be sk ipped. To demonstr ate wha t eff ect this c ommand has on the displa y, enter a v alue of 4 under Skip (not e tha t the v alue en tered must b e an in teger). This will r esult in thr ee in termedia te lab els being sk ipped, with the first and the last c olor map v alues alw ays being displa yed ( Fig- ure 40.35: The C olor map with S kipped Lab els (p.2827 )). •To reset the or iginal c olor map displa y, simply selec t Show A ll. Figur e 40.34: The D efault C olor map L abel D ispla y Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2826Displa ying G raphicsFigur e 40.35: The C olor map with S kipped L abels 40.2.5.4. Creating a C ustomiz ed C olormap You c an cr eate your o wn c olor map b y manipula ting the “anchor c olors ” and the c olor map siz e. A color sc ale is cr eated b y linear in terpolation b etween the anchor c olors .The c olor , numb er, and p os- ition of the anchor c olors will ther efore control the descr iption of the c olor map . By incr easing the color map siz e, you c an incr ease the t otal numb er of c olors and obtain a c olor sc ale tha t changes mor e gr adually .The pr ocedur e is as f ollows: 1. In the Color map D ialog Box (p.3697 ), click Edit... to op en the Color map E ditor D ialog Box (p.3699 ) (Fig- ure 40.36: The C olor map E ditor D ialog Box (p.2828 )). 2827Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Customizing the G raphics D ispla yFigur e 40.36: The C olor map E ditor D ialo g Box 2. In the Color map E ditor D ialog Box (p.3699 ), selec t a c olor sc ale in the Currently D efined list as y our starting p oint.The c olors in the sc ale will b e displa yed a t the t op of the dialo g box. A whit e bar b elow a color is an "anchor p oint" indic ating tha t this c olor is an "anchor c olor" . 3. If you w ant to add mor e colors t o the c olor sc ale, incr ease the Color map S ize; to use f ewer colors , de- crease this v alue .When y ou use the c oun ter ar rows (or t ype in a v alue and pr ess Enter), the c olor sc ale displa y at the t op of the dialo g box will b e up dated immedia tely. Imp ortant The t otal numb er of c olors must not b e less than the numb er of anchor p oints. 4. To obtain the desir ed c olor sc ale in terpolation, manipula te the anchor c olors as needed: •To add an anchor p oint, click an y mouse butt on on the black spac e dir ectly b elow the desir ed anchor color (or click the c olor itself ). A whit e bar will app ear b elow the c olor t o iden tify it as an anchor c olor , and the c olor will aut oma tically b e selec ted f or color-definition mo dific ation. •To remo ve an anchor p oint, click the whit e bar b elow the anchor c olor .The whit e bar will disapp ear and the c olor sc ale will b e up dated t o reflec t the new in terpolation. •To selec t a cur rent anchor c olor in or der t o mo dify its c olor definition, click the c olor itself a t the t op of the dialo g box. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2828Displa ying G raphics•To mo dify the c olor of the selec ted anchor c olor , you c an change either the r ed/gr een/blue c omp on- ents (cho ose RGB, the default) or the hue/sa turation/v alue c omp onen ts (cho ose HSV ).HSV is recom- mended if y ou plan t o record the gr aphics displa y on video , as it enables y ou t o create a mor e subtle gradation of c olor and r educ e the t endenc y of br ight colors t o “bleed ”. Move the Red ,Green , and Blue or Hue ,Saturation , and Value sliders t o obtain the desir ed c olor .The c olor sc ale a t the t op of the dialo g box will b e up dated aut oma tically t o sho w the eff ect of y our change . Imp ortant It is a go od idea t o not e the or iginal v alue of a c olor c omp onen t before mo ving the slider so tha t you will b e able t o retur n to it if y ou change y our mind . (See Scales (p.567) for instr uctions on using a sc ale slider .) If you mak e a mistak e while mo difying the c olor sc ale, you c an star t over b y selec ting the star ting- point color map in the Currently D efined list. 5. If you w ant to change the default name of the new c olor map , enter the new name in the Name field . By default , cust om c olor maps ar e called cmap-0 ,cmap-1 , and so on. 6. Click OK to sa ve the new c olor map .The c olor map name app ears in the Currently D efined list in the Color map D ialog Box (p.3697 ) and c an b e selec ted f or use in the gr aphics displa y. Custom c olor map definitions will b e sa ved in the c ase file . 40.2.6. Adding Ligh ts In ANSY S Fluen t you c an add ligh ts with a sp ecified c olor and dir ection t o your displa y.These ligh ts can enhanc e the app earance of the displa y when it c ontains 3D geometr ies. By default one ligh t is defined .You c an enable the eff ect of the e xisting ligh t(s) using the Displa y Options D ialog Box (p.3681 ) or the Ligh ts D ialog Box (p.3696 ), and y ou c an add new ligh ts using the Ligh ts D ialog Box (p.3696 ). 40.2.6.1. Turning on Lighting E ffec ts with the D ispla y O ptions D ialo g Box To enable the eff ect of ligh ting , you c an use the Displa y Options D ialog Box (p.3681 ). Results → Graphics Options ... If you enable the Ligh ts On option under Ligh ting A ttribut es and click Apply , you will see the ligh ting eff ects in the ac tive gr aphics windo w.To tur n off the ligh ting eff ects, simply tur n off the Ligh ts On option and click Apply . You c an also cho ose the metho d to be used in ligh ting in terpolation; selec t Flat,Gour aud , or Phong in the Ligh ting drop-do wn list. Flat is the most basic metho d: ther e is no in terpolation within the individual p olygonal fac ets. Gouraud and P hong ha ve smo other gr adations of c olor b ecause the y in- terpolate on each fac et. 40.2.6.2. Turning on Lighting E ffec ts with the Lights Dialo g Box You c an also enable ligh ting eff ects using the Ligh ts D ialog Box (p.3696 ) (Figur e 40.37: The Ligh ts D ialog Box (p.2830 )). 2829Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Customizing the G raphics D ispla yResults → Graphics Ligh ts... For c onstan t ligh ting eff ects in the dir ection of the view , enable the Headligh t On option in the Ligh ts D ialog Box (p.3696 ).This option has the eff ect of a ligh t sour ce dir ectly in fr ont of the mo del, no ma tter wha t orientation the mo del is view ed in. To disable this f eature, turn off the Headligh t On option in the Ligh ts D ialog Box (p.3696 ). In the Ligh ting M etho d drop-do wn list , cho ose Flat,Gour aud , or Phong to enable the appr opriate ligh ting metho d.These metho ds ar e descr ibed in the pr evious sec tion. To disable ligh ting , selec t Off in the list. To see the ligh ting eff ects in the ac tive gr aphics windo w, click Apply . 40.2.6.3. Defining Light S our ces You c an c ontrol individual ligh ts in the Ligh ts D ialog Box (p.3696 ) (Figur e 40.37: The Ligh ts D ialog Box (p.2830 )).The Ligh ts D ialog Box (p.3696 ) enables y ou t o cr eate a ligh t and then tur n it off without deleting it. In this w ay, you c an r etain ligh ts tha t you ha ve defined pr eviously but do not w ant to use at presen t. Results → Graphics Ligh ts... Figur e 40.37: The Ligh ts D ialo g Box (You c an also op en the Ligh ts D ialog Box (p.3696 ) by click ing Ligh ts... in the Displa y Options D ialog Box (p.3681 ).) By default , ligh t 0 is defined t o be dar k gr ay with a dir ection of (1,1,1). A ligh t sour ce is a distan t ligh t, similar t o the sun. The dir ection (1,1,1) means tha t the r ays from the ligh t will b e par allel t o the v ector from (1,1,1) t o the or igin. To cr eate an additional ligh t (for e xample , ligh t 1), follow the st eps list ed below. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2830Displa ying G raphics1. Increase Ligh t ID to a new v alue (f or e xample ,1). 2. Enable the Ligh t On check b ox. 3. Define the ligh t color b y en tering a descr iptiv e str ing (f or e xample ,lavender ) in the Color field , or by mo ving the Red ,Green , and Blue sliders t o obtain the desir ed c olor .The default c olor f or all ligh ts is dar k gr ay. 4. Specify the ligh t dir ection b y doing one of the f ollowing: •Enter the ( X,Y,Z) Cartesian c omp onen ts under Direction . •Click the middle mouse butt on in the desir ed lo cation on the spher e under Active Ligh ts. (You c an also mo ve the ligh t along the cir cles on the sur face of the spher e by dr agging the mouse while holding do wn the middle butt on.) You c an r otate the spher e by pr essing the lef t mouse butt on and moving the mouse (lik e a tr ackball). •Use y our mouse t o change the view in the gr aphics windo w so tha t your p osition in r eference to the geometr y is the p osition fr om which y ou w ould lik e a ligh t to shine .Then click Use View Vector to update the X,Y,Z fields with the appr opriate values f or y our cur rent position and up date the gr aphics displa y with the new ligh t dir ection. This metho d is c onvenien t if y ou k now wher e you w ant a ligh t to be, but y ou ar e not sur e of the e xact dir ection v ector. 5. Repeat steps 1–4 t o add mor e ligh ts. 6. When y ou ha ve defined all the ligh ts you w ant, click Apply to sa ve their definitions . 40.2.6.3.1. Remo ving a Light To remo ve a ligh t, enter the ID numb er of the ligh t to be remo ved in the Ligh t ID field and then clear the Ligh t On check b ox.When a ligh t is tur ned off , its definition is r etained , so y ou c an easily add it t o the displa y again a t a la ter time b y selec ting the Ligh t On check b ox. For e xample , you may want to define thr ee diff erent ligh ts to be used in diff erent scenes .You c an define each of them, and then enable only one or t wo at a time , using the Ligh t ID field and the Ligh t On check box. Onc e you ha ve made all the desir ed mo dific ations t o the ligh ts, rememb er to click Apply to save the changes . 40.2.6.3.2. Resetting the Light D efinitions If you ha ve made changes t o the ligh t definitions , but y ou ha ve not y et click ed Apply , you c an r eset the ligh ts b y click ing Reset . All ligh ting char acteristics will r evert to the last sa ved sta te (tha t is, the ligh ting tha t was in eff ect the last time y ou op ened the dialo g box or click ed on Apply ). 40.2.7. Modifying the Render ing Options Depending on the objec ts in y our displa y windo w and wha t kind of gr aphics har dware and sof tware you ar e using , you ma y want to mo dify some of the r ender ing par amet ers list ed b elow. All are list ed under the Render ing heading in the Displa y Options D ialog Box (p.3681 ) (Figur e 40.30: The D ispla y Options D ialog Box (p.2819 )). Results → Graphics Options ... 2831Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Customizing the G raphics D ispla yAfter mak ing a change t o an y of these r ender ing par amet ers, click Apply to re-render the sc ene in the ac tive gr aphics windo w with the new a ttribut es.To see the eff ect of the new a ttribut es on another graphics windo w, you must r edispla y it or mak e it the ac tive windo w (see Setting the A ctive Win- dow (p.2819 )) and click Apply again. Line Width : By default , all lines dr awn in the displa y ha ve a thick ness of 1 pix el. If you w ant to incr ease the thick ness of the lines , incr ease the v alue of Line Width . Point Symb ol: By default , nodes displa yed on sur faces and da ta p oints on line or r ake sur faces ar e represen ted in the displa y by a + sign inside a cir cle. If you w ant to mo dify this r epresen tation (f or e xample , to mak e the nodes easier t o see), you c an selec t a diff erent symb ol in the Point Symb ol drop-do wn list. Anima tion Options : There are two anima tion options tha t you c an cho ose fr om. They are as f ollows: All uses a solid-t one shading r epresen tation of all geometr y dur ing mouse manipula tion. Wireframe uses a wir eframe r epresen tation of all geometr y dur ing mouse manipula tion. If your c omput er has a graphics acc elerator, you ma y not w ant to use this option; other wise , the mouse manipula tion ma y be very slo w. Double Buff ering: Enabling the Double Buff ering option c an dr ama tically r educ e scr een flick er dur ing gr aphics up dates. Note, however, tha t if y our displa y har dware do es not supp ort double buff ering and y ou tur n this option on, double buff ering will b e done in sof tware. Software double buff ering uses e xtra memor y. Out er F ace Culling : This option enables y ou t o tur n off the displa y of out ward pointing fac es of shells or meshes .This is sometimes useful f or displa ying b oth sides of a slit w all. By default , when y ou displa y a slit w all, one side will “bleed ” through t o the other .When y ou enable the Out er F ace Culling option, the displa y of a slit wall will sho w each side distinc tly as y ou r otate the displa y.This option c an also b e useful f or displa ying two-sided w alls (tha t is, walls with fluid or solid c ells on b oth sides). Please not e, however, tha t enabling it can also hides some unin tended sur faces on c ertain viewing angles , e.g. while displa ying C ontours , it migh t be visible only fr om one side of the sur face and not fr om the other Hidden S urface Remo val: If you do not use hidden sur face remo val, ANSY S Fluen t will not tr y to det ermine which sur faces in the displa y are behind others; it will displa y all of them, and a clutt ered displa y will r esult f or most 3D mesh displa ys. For most 3D pr oblems , ther efore, you should enable the Hidden S urface Remo val option. You should tur n this option off (f or optimal p erformanc e) if y ou ar e working with a 2D pr oblem or with geo- metr ies tha t do not o verlap. You c an cho ose one of the f ollowing metho ds for p erforming hidden sur face remo val in the Hidden Surface M etho d drop-do wn list. These options v ary in sp eed and qualit y, dep ending on the de vice you ar e using . Hardware Z-buff er is the fast est metho d if y our har dware supp orts it. The accur acy and sp eed of this metho d is har dware- dep enden t. Note tha t if this metho d is not a vailable on y our c omput er, selec ting it will c ause the Software Z-buff er metho d to be used . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2832Displa ying G raphicsPainters will sho w fewer edge-aliasing eff ects than Hardware-Z-buff er.This metho d is of ten used inst ead of Software-Z-buff er when memor y is limit ed. Software Z-buff er is the fast est of the accur ate sof tware metho ds a vailable (esp ecially f or comple x scenes), but it is memor y-intensiv e. Z-sor t only is a fast sof tware metho d, but it is not as accur ate as Software-Z-buff er. 40.2.7.1. Graphics D evice Information If you need t o know which gr aphics dr iver y ou ar e using and wha t graphics har dware it r ecogniz es, you c an click Info in the Displa y Options D ialog Box (p.3681 ).The gr aphics de vice inf ormation will b e printed in the t ext (console) windo w. 40.3. Controlling the M ouse Butt on F unc tions A convenien t feature of ANSY S Fluen t is tha t it enables y ou t o assign a sp ecific func tion t o each of the mouse butt ons. According t o your sp ecific ations , click ing a mouse butt on in the gr aphics windo w will cause the appr opriate ac tion t o be tak en.These func tions apply only t o the gr aphics windo ws; the y behave diff erently when an X Y plot or hist ogram is displa yed. For inf ormation ab out the use of mouse butt ons in these plots , see Plot Types (p.2863 ). Clicking an y mouse butt on in a gr aphics windo w will mak e tha t windo w the ac tive windo w. Imp ortant 3Dc onne xion S pace pr oduc ts (M ouse , Pilot, and N aviga tor) ar e not supp orted with ANSY S Fluen t. For additional inf ormation, see the f ollowing sec tions: 40.3.1. Button F unctions 40.3.2. Modifying the M ouse B utton F unctions 40.3.1. Butt on F unc tions The pr edefined butt on func tions a vailable ar e list ed b elow: mouse-r otate Enables y ou t o rotate the view b y dr agging the mouse acr oss the scr een. Dragging hor izontally r otates the objec t ab out the scr een’s -axis; vertical mouse mo vemen t rotates the objec t ab out the scr een’s -axis .The func tion c omplet es when the mouse butt on is r eleased or the cursor lea ves the gr aphics windo w. mouse-dolly Enables y ou t o transla te the view b y dr agging the mouse while holding do wn the butt on.The func tion complet es when the mouse butt on is r eleased or the cursor lea ves the gr aphics windo w. 2833Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Controlling the M ouse B utton F unctionsmouse-scr oll-z oom (non-mo difiable) Enables y ou t o use the middle scr oll-wheel t o zoom in and out on the gr aphics windo w based on the location of the mouse p ointer. mouse-z oom Enables y ou t o dr aw a z oom b ox, anchor ed a t the p oint at which the butt on w as pr essed , by dr agging the mouse with the butt on held do wn. When y ou r elease the butt on, if the dr agging w as fr om lef t to right, a magnified view of the ar ea within the z oom b ox will fill the windo w. If the dr agging w as fr om right to lef t, the ar ea of the windo w is shr unk t o fit in to the z oom b ox, resulting in a “zoomed out ” view . If the mouse butt on is simply click ed (not dr agged), the selec ted p oint becomes the c enter of the windo w. mouse-r oll-z oom Enables y ou t o rotate or z oom the view , dep ending on the dir ection in which y ou dr ag the mouse . If you drag the mouse hor izontally , the displa y will r otate ab out the axis nor mal t o the scr een. If you dr ag it vertically, the displa y will b e magnified (if y ou dr ag it do wn) or shr unk (if y ou dr ag it up). The func tion complet es when the mouse butt on is r eleased or the cursor lea ves the gr aphics windo w. mouse-pr obe Enables y ou t o selec t items fr om the gr aphics windo ws and r equest inf ormation ab out displa yed sc enes . If you ha ve selec ted shor t descr iption from the Probe drop-do wn list and then click the mouse-pr obe butt on in the gr aphics windo w, only the iden tity of the it em on which y ou click ed will b e pr inted out in the c onsole; if you ha ve selec ted long descr iption inst ead, mor e detailed inf ormation ab out a selec ted item will b e displa yed. Note A lef t-click will alw ays selec t unless the lef t-mouse-butt on is set as mouse-z oom or mouse- probe. 40.3.2. Modifying the M ouse Butt on F unc tions Mouse butt on func tions ar e sp ecified in the View tab . View For each mouse butt on ( Left,Middle , and Right), selec t the desir ed func tion in the dr op-do wn list. The func tions ar e list ed ab ove. If you assign the pr obe func tion t o one of the butt ons, selec t shor t descr iption or long descr iption from the Probe drop-do wn list t o indic ate the amoun t of detail y ou want displa yed in the c onsole . The new butt on func tions tak e eff ect as so on as the y are changed .That is, you do not ha ve to redraw the gr aphics windo w to use the new func tions; the appr opriate func tion will b e execut ed when a mouse butt on is subsequen tly click ed in a gr aphics windo w. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2834Displa ying G raphicsThe ANSY S Fluen t Defaults butt on func tions ar e as f ollows: 3D A ction 2D A ction Operation Key Mouse Butt on Rota te Pan/dolly Drag Left Selec t Selec t Click Left Add or r emo ve selec tion Add or r emo ve selec tion Click Ctrl Left Zoom Zoom Scroll Middle Box-zoom Box-zoom Drag Middle Box-zoom Box-zoom Drag Shift Middle Pan/dolly Pan/dolly Drag Ctrl Middle Probe/context menu Probe/context menu Click Right Probe/context menu Probe/context menu Drag Right Probe/context menu Probe/context menu Click Shift Right The Workbench D efaults butt on func tions ar e as f ollows: 3D A ction 2D A ction Operation Key Mouse Butt on Pan/dolly Pan/dolly Drag Left Selec t Selec t Click Left Add or r emo ve selec tion Add or r emo ve selec tion Click Ctrl Left Zoom Zoom Scroll Middle Rota te Probe Drag Middle Box-zoom Probe Drag Shift Middle Pan/dolly Probe Drag Ctrl Middle Context menu Context menu Click Right Zoom Zoom Drag Right Fit to center Fit to center Click Shift Right 40.4. Viewing the A pplic ation Windo w In ANSY S Fluen t, the applic ation windo w houses the r ibbon and c onsole , as w ell as multiple gr aphics windo ws, task pages , and the tr ee. By default , all c omp onen ts ar e displa yed and one gr aphics windo w is visible .You c an t oggle the visibilit y of the t oolbars , task page , console , and gr aphics windo w using in the standar d toolbar .The r ibbon and the tr ee ar e ne ver fully hidden—y ou c an hide the r ibbon contents using (also in the standar d toolbar), but the tab names ar e alw ays visible .You also ha ve the option of viewing separ ate gr aphics windo ws as descr ibed in Opening M ultiple G raphics Win- dows (p.2818 ). For additional inf ormation ab out the v arious elemen ts of the applic ation windo w, see Graphic al U ser In terface (GUI) (p.549). 40.5. Modifying the View ANSY S Fluen t enables y ou t o selec t and c ontrol the view of the sc ene tha t is displa yed in the gr aphics windo w.You c an mo dify the view b y sc aling , centering, rotating , transla ting , or z ooming the displa y. 2835Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modifying the ViewYou c an also sa ve a view tha t you ha ve created, or r estore or delet e a view tha t you sa ved ear lier.These operations ar e performed in the Views Dialog Box (p.3690 ) (Figur e 40.39: The Views Dialog Box (p.2838 )) or with the mouse , or simply using the shor tcut in the gr aphics t oolbar , as descr ibed in Selec ting a View (p.2836 ). Imp ortant You c an r evert to the pr evious view b y pr essing Ctrl+L while the gr aphics windo w has the main f ocus.You c an also use the t ext command view last from the t op le vel of the t ext command tr ee.You c an use the c ommand t o revert to an y of the past 20 view s. For additional inf ormation, see the f ollowing sec tions: 40.5.1. Selec ting a View 40.5.2. Manipula ting the D ispla y 40.5.3. Controlling P ersp ective and C amer a Paramet ers 40.5.4. Saving and R estoring Views 40.5.5. Mirroring and P eriodic R epeats 40.5.1. Selec ting a View You c an use the Views Dialog Box (p.3690 ) (Figur e 40.39: The Views Dialog Box (p.2838 )) to selec t the orientation of y our displa y or use the drop-do wn a vailable in the gr aphics t oolbar f or 3D simula- tions . Further mor e, you c an simply click the in teractive triad ( Figur e 40.38: Using the Triad t o Change the Or ientation of the O bjec t (p.2837 )), displa yed in the gr aphics windo w.The Table 40.1: Standar d Views (p.2836 ) relates the Views listed in the Views Dialog Box (p.3690 ) to the view s available in the graphics t oolbar (see Pointer Tools (p.557)). Results → Graphics Views... Table 40.1: Standar d Views View S hor tcut in G raphics ToolbarView List ed in Dialo g Box back bottom front isometr ic left right top Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2836Displa ying G raphicsFigur e 40.38: Using the Triad t o Change the Or ientation of the O bjec t To change the or ientation of the objec t in the gr aphics windo w using the tr iad ( Figur e 40.38: Using the Triad t o Change the Or ientation of the O bjec t (p.2837 )), you c an •Click an axis/semi-spher e to point it in the p ositiv e/nega tive dir ection. •Right-click an axis/semi-spher e to point it in the nega tive/positiv e dir ection. •Click the c yan iso-ball t o set the isometr ic view . •Click the whit e rotational ar rows at the b ottom of the tr iad t o perform in-plane clo ckwise or c oun terclockwise 90 degr ee rotations . •Left-click and hold—in the vicinit y of the tr iad—and use the mouse t o perform fr ee-r otations in an y dir ection. Release lef t mouse butt on t o stop r otating . Note tha t click ing on the X-axis will r esult in the +X-axis p ointing t owards y ou. Note For 2D c ases , the drop-do wn and the in teractive triad ar e not a vailable; in a fr ont view , the X-axis is hor izontal with the p ositiv e dir ection t o the r ight, the Y-axis is v ertical with the positiv e dir ection p ointing up , and the Z-axis is det ermined b y the r ight-hand r ule. 40.5.2. Manipula ting the D ispla y Most of the manipula ting ac tivities (lik e sc aling and c entering the displa y) ar e acc omplished using the Views Dialog Box (p.3690 ) (Figur e 40.39: The Views Dialog Box (p.2838 )). Results → Graphics Views... 2837Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modifying the ViewFigur e 40.39: The Views Dialo g Box You c an r otate, transla te, and z oom the gr aphics displa y using either the mouse or the Camer a Para- met ers D ialog Box (p.3695 ) (Figur e 40.40: The C amer a Paramet ers D ialog Box (p.2838 )), which is op ened from the Views Dialog Box (p.3690 ). Figur e 40.40: The C amer a Paramet ers D ialo g Box 40.5.2.1. Scaling and C ent ering You c an sc ale and c enter the cur rent displa y without changing its or ientation b y click ing Auto Sc ale in the Views Dialog Box (p.3690 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2838Displa ying G raphics40.5.2.2. Rotating the D ispla y Use either the mouse or the Camer a Paramet ers D ialog Box (p.3695 ) to: •Rotate the displa y in an y dir ection (in 3D) •Rotate the displa y ab out the axis nor mal t o the scr een (in 2D) To rotate a displa y with the mouse , use the butt on with the mouse-r otate func tion (the lef t butt on, by default). For inf ormation ab out changing the mouse func tions , see Controlling the M ouse B utton Functions (p.2833 ). •Click and dr ag the lef t mouse butt on in the gr aphics windo w to rotate the geometr y in the displa y. •You c an also click and dr ag the lef t mouse butt on on the ( , , ) graphics tr iad in the lo wer lef t corner t o rotate the displa y. •If you pr ess the Shift key when y ou first click the mouse butt on t o begin the r otation, the r otation will b e constr ained t o a single dir ection (f or e xample , you c an r otate ab out the scr een’s hor izontal axis without changing the p osition r elative to the v ertical axis). •If you w ant to constr ain the r otation of a displa y to be ab out the axis nor mal t o the scr een, you c an also use the mouse-r oll-z oom func tion. •Click the appr opriate mouse butt on and dr ag the mouse t o the lef t for clo ckwise r otation, or t o the right for coun terclockwise r otation. To rotate a 3D displa y using the Camer a Paramet ers D ialog Box (p.3695 ) (Figur e 40.40: The C amer a Paramet ers D ialog Box (p.2838 )) use the dial and the slider of the sc ales . •To rotate ab out the hor izontal axis a t the c enter of the scr een, mo ve the slider on the sc ale t o the lef t of the dial up or do wn (see Scales (p.567) or instr uctions on using the sc ale). •To rotate ab out the v ertical axis a t the c enter of the scr een, mo ve the slider on the sc ale b elow the dial to the lef t or r ight. •To rotate ab out the axis a t the c enter of and p erpendicular t o the scr een, click the lef t mouse butt on on the indic ator in the dial and dr ag it ar ound the dial. Imp ortant The p osition of the slider or the dial indic ator do es not r eflec t the cumula tive rotation about the axis as the slider/indic ator will r etur n to its or iginal p osition when y ou r elease the mouse butt on. 40.5.2.2.1. Spinning the D ispla y with the Mouse When y ou use the mouse f or rotation, you ha ve the option t o “push ” the displa y into a c ontinuous spin. This f eature can b e used in c onjunc tion with video r ecording , or simply f or in teractive viewing of the domain fr om diff erent angles .To use this option, use the auto-spin? text command: display → set → rendering-options → auto-spin? 2839Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modifying the ViewThen displa y the gr aphics (or , if the gr aphics ar e alr eady displa yed, you c an click Apply in the Displa y Options D ialog Box (p.3681 )).The mouse-r otate butt on will then ha ve two uses: •To perform the standar d rotation, stop dr agging the mouse b efore you r elease the mouse-r otate butt on. •To star t the c ontinuous spin, release the mouse-r otate butt on while y ou ar e still dr agging the mouse . The displa y will c ontinue t o rotate on its o wn un til you click an y mouse butt on in the gr aphics windo w again. The sp eed of the r otation will dep end on ho w fast y ou ar e dr agging the mouse when y ou r elease the butt on. For smo other r otation, enable the Double Buff ering option in the Displa y Options D ialog Box (p.3681 ) (see Modifying the R ender ing Options (p.2831 )).This will r educ e scr een flick er dur ing gr aphics up dates. 40.5.2.3. Translating the D ispla y By default the lef t mouse butt on is set t o mouse-dolly in 2D . For inf ormation ab out changing the mouse func tions , see Controlling the M ouse B utton F unctions (p.2833 ). Click and dr ag the lef t mouse butt on in the gr aphics windo w to transla te the geometr y in the displa y. In 3D , you c an either change one of the butt on func tions t o mouse-dolly and f ollow the instr uctions above for 2D , or use the mouse-z oom butt on (the middle butt on b y default). Click the middle butt on once on the p oint in the displa y tha t you w ant to mo ve to the c enter of the scr een. ANSY S Fluen t will redispla y the gr aphic with tha t point in the c enter of the windo w.This metho d can also b e used in 2D. 40.5.2.4. Zooming the D ispla y In b oth 2D and 3D y ou will use the mouse butt on with the mouse-z oom func tion (the middle butt on by default) or the mouse-r oll-z oom func tion (see Controlling the M ouse B utton F unctions (p.2833 ) for inf ormation ab out enabling this optional func tion), or the Camer a Paramet ers D ialog Box (p.3695 ) to magnify and shr ink the displa y. With the mouse-z oom func tion, click the middle mouse butt on and dr ag it fr om lef t to right (cr eating a "zoom b ox") to magnify the displa y.Figur e 40.41: Zooming In (M agnifying the D ispla y) (p.2841 ) displa ys the c orrect dragging of the mouse , from upp er lef t to lo wer right on the displa y, in or der t o zoom. You c an also dr ag fr om lo wer lef t to upp er right. After y ou r elease the mouse butt on, ANSY S Fluen t will redispla y the gr aphic , filling the gr aphics windo w with the p ortion of the displa y tha t previously o c- cupied the z oom b ox. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2840Displa ying G raphicsFigur e 40.41: Zooming In (M agnifying the D ispla y) Figur e 40.42: Zooming Out (S hrinking the D ispla y) Click the middle mouse butt on and dr ag it fr om r ight to lef t to shr ink the displa y.Figur e 40.42: Zooming Out (S hrinking the D ispla y) (p.2841 ) displa ys the c orrect dragging of the mouse , from lo wer right to upp er lef t on the displa y, in or der t o "zoom out" .You c an also dr ag fr om upp er right to lo wer lef t. After y ou r elease the mouse butt on, ANSY S Fluen t will r edispla y the gr aphic , shr inking the gr aphic al displa y by the r atio of siz es of the z oom b ox you cr eated and the pr evious displa y. With the mouse-r oll-z oom func tion, click the appr opriate mouse butt on and dr ag the mouse do wn to zoom in c ontinuously , or up t o zoom out. In the Camer a Paramet ers D ialog Box (p.3695 ) (Fig- ure 40.40: The C amer a Paramet ers D ialog Box (p.2838 )), use the sc ale t o the r ight of the dial t o zoom the displa y. Move the slider bar up t o zoom in and do wn t o zoom out. 2841Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modifying the View40.5.3. Controlling P ersp ective and C amer a Paramet ers Persp ective and other c amer a par amet ers ar e defined in the Views Dialog Box (p.3690 ), which y ou c an open b y click ing Camer a... in the Camer a Paramet ers D ialog Box (p.3695 ) (Figur e 40.39: The Views Dialog Box (p.2838 )). Results → Graphics Views... 40.5.3.1. Persp ective and O rtho graphic Views You ma y cho ose t o displa y either an or thographic view or a p ersp ective view of y our gr aphics .To show a p ersp ective view (the default), selec t Persp ective in the Projec tion drop-do wn list in the Views Dialog Box (p.3690 ) (Figur e 40.40: The C amer a Paramet ers D ialog Box (p.2838 )).To tur n off p er- spective, selec t Ortho graphic in the Projec tion drop-do wn list. 40.5.3.2. Mo difying C amer a Paramet ers Instead of tr ansla ting , rotating , and z ooming the displa y as descr ibed in Manipula ting the D is- play (p.2837 ), you ma y sometimes w ant to mo dify the “camer a” through which y ou ar e viewing the graphics displa y. The c amer a is defined b y four par amet ers: position, target, up v ector, and field , as illustr ated in Fig- ure 40.43: Camer a Definition (p.2842 )."Position" is the c amer a’s location. "Target" is the lo cation of the point the c amer a is lo oking a t, and "up v ector" indic ates to the c amer a which w ay is up ."Field" indic ates the field of view (width and heigh t) of the displa y. Figur e 40.43: Camer a D efinition To mo dify the c amer a’s position, selec t Position in the Camer a drop-do wn list and sp ecify the X,Y, and Z coordina tes of the desir ed p oint.To mo dify the tar get lo cation, selec t Target in the Camer a drop-do wn list and sp ecify the c oordina tes of the desir ed p oint. Selec t Up Vector to change the up Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2842Displa ying G raphicsdirection. The up v ector is the v ector fr om (0,0,0) t o the sp ecified ( X,Y,Z) point. Finally , to change the field of view , selec t Field in the Camer a list and en ter the X (hor izontal) and Y (vertical) field distanc es. Imp ortant Click Apply after y ou change each c amer a par amet er (Position ,Target,Up Vector, and Field ). 40.5.4. Saving and Rest oring Views After y ou mak e changes t o the view sho wn in y our gr aphics windo w, you ma y want to sa ve the view so tha t you c an r etur n to it la ter. Several default view s are pr edefined f or y ou, and c an b e easily r estored. All sa ving and r estoring func tions ar e performed with the Views Dialog Box (p.3690 ) (Figur e 40.39: The Views Dialog Box (p.2838 )). Results → Graphics Views... Imp ortant Note tha t settings f or mir roring and p eriodic r epeats ar e not sa ved in a view . 40.5.4.1. Restoring the D efault View When e xperimen ting with diff erent view manipula tion t echniques , you ma y acciden tally "lose" your geometr y in the displa y.You c an easily r etur n to the default (fr ont) view b y click ing Default in the Views Dialog Box (p.3690 ). 40.5.4.2. Returning t o Previous Views After manipula ting the displa y and viewing it fr om diff erent angles , you c an r etur n to pr evious displa ys by click ing Previous in the Views Dialog Box (p.3690 ). 40.5.4.3. Saving Views Onc e you ha ve created a new view tha t you w ant to sa ve for futur e use , enter a name f or it in the Save Name field in the Views Dialog Box (p.3690 ) and click Save.Your new view will b e added t o the list of Views, and y ou c an r estore it la ter as descr ibed b elow. If a view with the same name alr eady exists , you will b e ask ed in a Question D ialog Box (p.569) if it is OK t o overwrite the e xisting view . If you o verwrite one of the default view s (top, left, right, front, and so on), be sur e to sa ve it in a view file if y ou w ant to use it in a la ter session. Although all view s are sa ved t o the c ase file , the default view s are recomput ed aut oma tically when a c ase file is r ead in. Any cust om view with the same name as a default view will b e overwritten a t tha t time . As men tioned pr eviously , all defined view s will b e sa ved in the c ase file when y ou wr ite one . If you plan t o use y our view s with another c ase file , you c an wr ite a “view file ” containing just the view s. You c an r ead this view file in to another F luen t session in volving a diff erent case file and r estore an y of the defined view s, as descr ibed b elow. 2843Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modifying the ViewTo sa ve a view file , click Write... in the Views Dialog Box (p.3690 ). In the r esulting Write Views Dialog Box (p.3692 ) (Figur e 40.44: The Write Views Dialog Box (p.2844 )), selec t the view s you w ant to sa ve in the Views to Write list and click OK.You will then use the Selec t File dialo g box to sp ecify the file name and sa ve the view file . See The S elec t File D ialog Box (p.569) for mor e details . Figur e 40.44: The Write Views Dialo g Box 40.5.4.4. Reading View F iles If you ha ve sa ved view s to a view file (as descr ibed ab ove), you c an r ead them in to your cur rent Fluen t session b y click ing Read ... in the Views Dialog Box (p.3690 ), and indic ating the name of the view file in The S elec t File D ialog Box (p.569). If a view tha t you r ead has the same name as a view tha t alr eady exists , you will b e ask ed in a Question D ialog Box (p.569) if it is OK t o overwrite (tha t is, replac e) the existing view . 40.5.4.5. Deleting Views If you decide tha t you no longer w ant to keep a par ticular view , you c an delet e it b y selec ting it in the Views list and click ing on Delet e. Use this option c arefully , so tha t you do not acciden tally delet e one of the pr edefined view s. 40.5.5. Mirroring and P eriodic Rep eats If you mo del the pr oblem domain as a subset of the c omplet e geometr y using symmetr y or p eriodic boundar ies, you c an displa y results on the c omplet e geometr y by mir roring or r epeating the domain. For e xample , only one half of the annulus sho wn in Figur e 40.45: Mirroring A cross a S ymmetr y Boundar y (p.2845 ) was mo deled , but the gr aphics ar e displa yed on b oth halv es.You c an also define mirror planes or p eriodic r epeats just f or gr aphic al displa y, even if y ou did not mo del y our pr oblem using symmetr y or p eriodic b oundar ies. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2844Displa ying G raphicsFigur e 40.45: Mirroring A cross a S ymmetr y Boundar y Displa y of symmetr y and p eriodic r epeats is c ontrolled in the Views Dialog Box (p.3690 ) (Figur e 40.46: The Views Dialog Box (p.2845 )). Results → Graphics Views... Figur e 40.46: The Views Dialo g Box For a symmetr ic domain, all symmetr y boundar ies ar e list ed in the Mirror P lanes list. Selec t one or mor e of these b oundar ies as the plane(s) ab out which t o mir ror the displa y. For a p eriodic domain, click Define ... to op en the Graphics P eriodicit y Dialog Box (p.3693 ), to acc ess the p eriodicit y par amet ers. Specify the numb er of times t o repeat the mo deled p ortion b y incr easing 2845Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modifying the Viewthe v alue of Numb er of Rep eats. If, for e xample , you mo deled a 90° sec tor of a duc t and y ou w anted to displa y results on the en tire duc t, you w ould set Numb er of Rep eats to 4. In some c ases , ther e ma y be multiple z ones with diff erent periodicit y in the domain. For e xample , in turb omachiner y pr oblems with multiple blade r ows using the mixing plane mo del, the p eriodic angles are diff erent for each blade r ow. One blade ma y contain 20 blades (18° p eriodic angle) and other ma y contain 15 blades (24° p eriodic angle). In such c ases selec t the r equir ed c ell z one and sp ecify the numb er of r epeats for tha t par ticular c ell z one . When y ou click Set in the Graphics P eriodicit y Dialog Box (p.3693 ) the gr aphics displa y will b e immedia tely updated t o sho w the r equest ed p eriodic r epeats. Figur e 40.47: Before Applying P eriodicit y (p.2846 ) and Figur e 40.48: After A pplying P eriodicit y (p.2846 ) shows the displa y for the sample geometr y before and af ter applying the p eriodic r epeats respectively. In this c ase the v alue of Numb er of Rep eats is set t o 6 for the 60° sec tor (out er par t) and t o a v alue of 4 is set f or the 90° sec tor (inner par t) of the geometr y. Figur e 40.47: Before Applying P eriodicit y Figur e 40.48: After A pplying P eriodicit y 40.5.5.1. Perio dic R epeats for Gr aphics To define gr aphic al p eriodicit y for a non-p eriodic domain, do the f ollowing: 1. Click Define ... under Periodic Rep eats in the Views Dialog Box (p.3690 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2846Displa ying G raphicsFigur e 40.49: The G raphics P eriodicit y D ialo g Box 2. In the r esulting Graphics P eriodicit y Dialog Box (p.3693 ) (Figur e 40.49: The G raphics P eriodicit y Dialog Box (p.2847 )), selec t the Cell Z one for which y ou w ant to sp ecify the numb er of r epeats. Asso ciat ed S urfaces list c ontains the sur faces asso ciat ed with the selec ted c ell z one .This is onl y in- formativ e and y ou c annot edit the selec tion of sur faces in this b ox. 3. Specify Rota tional or Transla tional as the Periodic Type. 4. For tr ansla tional p eriodicit y, specify the Transla tion distanc e of the r epeated domain in the X,Y, and Z directions . For rotational p eriodicit y, specify the axis ab out which the p eriodicit y is defined and the Angle by which the domain is r otated t o create the p eriodic r epeat. For 3D pr oblems , the axis of r otation is the v ector passing thr ough the sp ecified Axis Or igin and par allel t o the v ector fr om (0,0,0) t o the (X,Y,Z) point specified under Axis D irection . For 2D pr oblems , you will sp ecify only the Axis Or igin ; the axis of r otation is the -direction v ector passing thr ough the sp ecified p oint. 5. Specify Numb er of Rep eats for the selec ted c ell z one . 6. Click Set in the Graphics P eriodicit y Dialog Box (p.3693 ). 7. Follow the same pr ocedur e for other c ell z ones . 8. Click Apply in the Views Dialog Box (p.3690 ) to visualiz e the mo dified displa y. You c an delet e the definition of an y periodicit y you ha ve defined f or gr aphics b y click ing Reset in the Graphics P eriodicit y Dialog Box (p.3693 ). Note For the 3D domain with multiple p eriodic z ones ha ving diff erent periodicit y, ANSY S Fluen t can r epeat only mesh, contour and v ector plots , and not the pa thlines and par ticle tr acks . Also if such domain c ontains , isosur faces and clip-sur faces, tha t are asso ciated with a par- 2847Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Modifying the Viewticular c ell z one , the y are repeated using the same p eriodicit y tha t is defined f or tha t cell zone . However, if the sur face is not asso ciated with an y cell z one , you c annot sp ecify the periodicit y for tha t sur face. 40.5.5.2. Mirroring for Gr aphics To define a mir ror plane f or a non-symmetr ic domain, do the f ollowing: 1. Click Define P lane ... under Mirror P lanes in the Views Dialog Box (p.3690 ). Figur e 40.50: The M irror P lanes D ialo g Box 2. In the r esulting Mirror P lanes D ialog Box (p.3693 ) (Figur e 40.50: The M irror P lanes D ialog Box (p.2848 )), set the c oefficien ts of X,Y, and Z and the Distanc e (of the plane fr om the or igin) in the f ollowing equa tion for the mir ror plane: (40.1) 3. Click Add to add the defined plane t o the Mirror P lanes list. When y ou ar e done cr eating mir ror planes , click OK.The newly defined plane(s) will no w app ear in the Mirror P lanes list in the Views Dialog Box (p.3690 ).To include the mir roring in the displa y, selec t the plane(s) and click Apply , as descr ibed above. If you w ant to delet e a mir ror plane tha t you ha ve defined , selec t it in the Mirror P lanes list in the Mirror P lanes D ialog Box (p.3693 ) and click Delet e.When y ou click OK in this dialo g box, the delet ed plane will b e remo ved p ermanen tly fr om the Mirror P lanes list in the Views Dialog Box (p.3690 ). 40.6. Advanc ed Sc ene C omp osition Figur e 40.51: The Sc ene D escr iption D ialog Box (p.2849 ) allo ws you t o cr eate a mor e comple x sc ene than wha t you c an cr eate using Figur e 40.26: The Sc ene D ialog Box (p.2812 ). Onc e you ha ve displa yed some geometr ic objec ts (meshes , sur faces, contours , vectors, and so on) in your gr aphics windo w, you ma y want to mo ve them ar ound and change their char acteristics t o incr ease the eff ectiveness of the sc ene displa yed.You c an use the Scene D escr iption D ialog Box (p.3683 ) (Fig- ure 40.51: The Sc ene D escr iption D ialog Box (p.2849 )) and the Displa y Properties D ialog Box (p.3685 ) (Fig- ure 40.52: The D ispla y Properties D ialog Box (p.2850 )) and Transf ormations D ialog Box (p.3687 ) (Fig- Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2848Displa ying G raphicsure 40.54: The Transf ormations D ialog Box (p.2853 )), which ar e op ened fr om within it , to rotate, transla te, and sc ale each objec t individually , as w ell as change the c olor and visibilit y of each objec t. View → Graphics → Comp ose ... Figur e 40.51: The Sc ene D escr iption D ialo g Box The Iso-V alue D ialog Box (p.3688 ) (Figur e 40.55: The I so-V alue D ialog Box (p.2854 )), which is also op ened from within the Scene D escr iption D ialog Box (p.3683 ), enables y ou t o change the iso value of a selec ted isosur face.The Pathline A ttribut es D ialog Box (p.3689 ) (Figur e 40.56: The P athline A ttribut es D ialog Box (p.2855 )) lets y ou set some pa thline a ttribut es.The abilit y to mak e geometr ic objec ts visible and in- visible is esp ecially useful when y ou ar e creating an anima tion (see Anima ting G raphics (p.2857 )) because it enables y ou t o add or delet e objec ts fr om the sc ene one a t a time .The abilit y to change the c olor and p osition of an objec t indep enden tly of the others in the sc ene is also useful f or setting up anima tions , as is the abilit y to change isosur face iso values .You will find the f eatures in the Scene D escr iption D ialog Box (p.3683 ) useful e ven when y ou ar e not gener ating anima tions b ecause the y enable y ou t o manage your gr aphics windo w efficien tly.The pr ocedur e for o verlaying gr aphics , which uses the Scene D escr ip- tion dialo g box, is descr ibed in Advanced G raphics O verlays (p.2817 ). (Note tha t you c annot use the Scene D escr iption D ialog Box (p.3683 ) to control X Y plot and hist ogram displa ys.) For additional inf ormation, see the f ollowing sec tions: 40.6.1. Selec ting the O bjec t(s) t o be Manipula ted 40.6.2. Changing an O bjec t’s Displa y Properties 40.6.3. Transf orming G eometr ic Objec ts in a Sc ene 40.6.4. Modifying I so-V alues 40.6.5. Modifying P athline A ttribut es 40.6.6. Deleting an O bjec t from the Sc ene 40.6.7. Adding a B ounding F rame 40.6.1. Selec ting the O bjec t(s) t o be M anipula ted In or der t o manipula te the objec ts in the sc ene, you will b egin b y selec ting the objec t or objec ts of interest in the Names list in the Scene D escr iption D ialog Box (p.3683 ) (Figur e 40.51: The Sc ene D escr iption 2849Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Advanced Sc ene C omp ositionDialog Box (p.2849 )).The Names list is a list of the geometr ic objec ts tha t cur rently e xist in the sc ene (including those tha t are pr esen tly in visible). If you selec t mor e than one objec t at a time , any op eration (transf ormation, color sp ecific ation, and so on) will apply t o all the selec ted objec ts.You c an also selec t objec ts b y click ing on them in the gr aphics displa y using the mouse-pr obe butt on, which is , by default , the r ight mouse butt on. (See Controlling the M ouse B utton F unctions (p.2833 ) for inf ormation ab out mouse butt on func tions .) To deselec t a selec ted objec t, simply click its name in the Names list. When y ou selec t one or mor e objec ts (either in the Names list or in the displa y), the Type field will report the t ype of the selec ted objec t(s). Possible t ypes for a single objec t include mesh ,surface , contour ,vector ,path , and text (tha t is, annota tion t ext).This inf ormation is esp ecially helpful when y ou need t o distinguish t wo or mor e objec ts with the same name .When mor e than one objec t is selec ted, the t ype displa yed is Group . 40.6.2. Changing an O bjec t’s Displa y Properties To enhanc e the sc ene in the gr aphics windo w, you c an change the c olor , visibilit y, and other displa y properties of each geometr ic objec t in the sc ene.You c an sp ecify diff erent colors f or displa ying the edges and fac es of a mesh objec t to sho w the under lying mesh (edges) when the fac es of the mesh are filled and shaded .You c an also mak e a selec ted objec t temp orarily in visible . If, for e xample , you are displa ying the en tire mesh f or a c omplic ated pr oblem, you c an mak e objec ts visible or in visible t o displa y only c ertain b oundar y zones of the mesh without r egener ating the mesh displa y using the Mesh D ispla y Dialog Box (p.3239 ).You c an also use the visibilit y controls t o manipula te geometr ic objec ts for efficien t graphics displa y or f or the cr eation of anima tions .These f eatures, plus se veral others , are available in the Displa y Properties D ialog Box (p.3685 ) (Figur e 40.52: The D ispla y Properties D ialog Box (p.2850 )). Figur e 40.52: The D ispla y Properties D ialo g Box Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2850Displa ying G raphicsTo set the displa y pr operties descr ibed ab ove, selec t one or mor e objec ts in the Names list in the Scene D escr iption D ialog Box (p.3683 ) and then click Displa y... to op en the Displa y Properties D ialog Box (p.3685 ) for tha t objec t or gr oup of objec ts. 40.6.2.1. Contr olling Visibilit y There ar e se veral w ays for y ou t o control the visibilit y of an objec t. All visibilit y options ar e list ed under the Visibilit y heading in the Displa y Properties D ialog Box (p.3685 ). •To mak e the selec ted objec t(s) in visible , turn off the Visible option. To “undo ” invisibilit y, enable the Visible option again. •To tur n the eff ect of ligh ting f or the selec ted objec t(s) on or off , use the Ligh ting check b ox.You c an choose t o ha ve ligh ting aff ect only c ertain objec ts inst ead of all of them. Note tha t if Ligh ting is tur ned on f or an objec t such as a c ontour or v ector plot , the c olors in the plot will not b e exactly the same as those in the c olor map a t the lef t of the displa y. •To toggle the filled displa y of fac es for the selec ted mesh or sur face objec t(s), use the Faces option. Turning Faces on her e has the same eff ect as tur ning it on f or the en tire mesh in the Mesh D ispla y Dialog Box (p.3239 ). •To tur n the displa y of out er edges on or off , use the Out er F aces option. This option is useful f or displa ying both sides of a slit w all. By default , when y ou displa y a slit w all, one side will “bleed ” through t o the other . When y ou tur n off the Out er F aces option, the displa y of a slit w all will sho w each side distinc tly as y ou rotate the displa y.This option c an also b e useful f or displa ying t wo-sided w alls (tha t is, walls with fluid or solid c ells on b oth sides). •To tur n the displa y of in terior and e xterior edges of the geometr ic objec t(s) on or off , use the Edges option. •To tur n the displa y of the outline of the geometr ic objec t(s) on or off , use the Perimet er E dges check box. •To toggle the displa y of f eature lines (descr ibed in Adding F eatures to an Outline D ispla y (p.2781 )), if an y, for the selec ted objec t(s), use the Feature Edges option. •To toggle the displa y of the lines (if an y) in the geometr ic objec t(s), use the Lines check b ox. Pathlines , line c ontours , and v ectors ar e “lines ”. •To toggle the displa y of no des (if an y) in the geometr ic objec t(s), use the Nodes check b ox. Onc e you ha ve set the appr opriate displa y par amet ers, click Apply to up date the gr aphics displa y. 40.6.2.2. Contr olling O bjec t Color and Transpar enc y The Displa y Properties D ialog Box (p.3685 ) also lets y ou c ontrol an objec t’s color and ho w tr anspar ent it is. All color and tr anspar ency options ar e list ed under the Colors heading . •To mo dify the c olor of fac es, edges , or lines in the selec ted objec t(s), cho ose face-color ,edge-c olor ,line- color , or node-c olor in the Color drop-do wn list. The Red ,Green , and Blue color sc ales will sho w the RGB c omp onen ts of the fac e, edge or line c olor , which y ou c an mo dify b y mo ving the sliders on the c olor scales .When y ou ar e sa tisfied with the c olor sp ecific ation, click Apply to sa ve it and up date the displa y. The abilit y to set the c olors f or fac es and edges c an b e useful when y ou w ant to ha ve a filled displa y for the mesh or sur face, but y ou also w ant to be able t o see the mesh lines .You c an achie ve this eff ect by specifying diff erent colors f or the fac es and the edges . 2851Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Advanced Sc ene C omp osition•To set the r elative transpar ency of an objec t, selec t face-color in the Color drop-do wn list. Move the slider on the Transpar enc y scale and click Apply to up date the gr aphics displa y. An objec t with a tr anspar ency of 0 is opaque , and an objec t with a tr anspar ency of 100 is tr anspar ent. By sp ecifying a high tr anspar ency value f or the w alls of a pip e, for e xample , you will b e able t o see c ontours tha t you ha ve displa yed on cross-sec tions inside the pip e.This f eature is a vailable on all pla tforms when the sof tware buff er is used for hidden sur face remo val, but if y our displa y har dware supp orts tr anspar ency, it will b e mor e efficien t to use the har dware buff er as the hidden sur face metho d inst ead.You c an selec t these metho ds in the Displa y Options D ialog Box (p.3681 ), as descr ibed in Modifying the R ender ing Options (p.2831 ). Imp ortant If you sa ve a pic ture of a displa y with tr anspar ent sur faces, you should not set the File Type in the Save Picture Dialog Box (p.3676 ) to Vector. 40.6.3. Transf orming G eometr ic O bjec ts in a Sc ene When y ou ar e comp osing a sc ene in y our gr aphics windo w, you migh t find it helpful t o mo ve a par tic- ular objec t from its or iginal p osition or t o incr ease or decr ease its siz e. For e xample , if y ou ha ve displa yed contours or v ectors on cr oss-sec tions of an in ternal flo w domain (such as a pip e), you migh t want to transla te these cr oss-sec tions so tha t the y will app ear outside of the pip e, wher e the y can b e seen and interpreted mor e easily .Figur e 40.53: Velocity Vectors Transla ted Outside the D omain f or B etter View- ing (p.2852 ) sho ws such an e xample . Figur e 40.53: Velocity Vectors Transla ted Outside the D omain f or B etter Viewing You c an also mo ve an objec t by rotating it ab out the -, -, or -axis . If you w ant to displa y one objec t mor e pr ominen tly than the others , you c an sc ale its siz e. If your geometr y is r otating or has r otational symmetr y, you c an displa y the mer idional view . All of these c apabilities ar e available in the Transf orm- ations D ialog Box (p.3687 ) (Figur e 40.54: The Transf ormations D ialog Box (p.2853 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2852Displa ying G raphicsFigur e 40.54: The Transf ormations D ialo g Box To perform the tr ansf ormations descr ibed ab ove, selec t one or mor e objec ts in the Names list in the Scene D escr iption D ialog Box (p.3683 ) and then click Transf orm... to op en the Transf ormations D ialog Box (p.3687 ) for tha t objec t or gr oup of objec ts. 40.6.3.1. Translating O bjec ts To transla te the selec ted objec t(s), enter the tr ansla tion distanc e in each dir ection in the X,Y, and Z real numb er fields under Transla te. Note tha t you c an check the domain e xtents in the Scale M esh Dialog Box (p.3238 ) or the Iso-Sur face Dialog Box (p.3842 ).Transla tions ar e not cumula tive, so y ou c an easily r etur n to a k nown sta te.To retur n to the or iginal p osition, simply en ter 0 in all thr ee r eal numb er fields . 40.6.3.2. Rotating O bjec ts To rotate the selec ted objec t(s), enter the numb er of degr ees b y which t o rotate ab out each axis in the X,Y, and Z integer numb er fields under Rota te By.You c an en ter an y value b etween and . By default , the r otation or igin will b e (0,0,0). If you w ant to spin an objec t ab out its o wn or igin, or ab out some other p oint, specify the X,Y, and Z coordina tes of tha t point under Rota te About. Rotations ar e not cumula tive, so y ou c an easily r etur n to a k nown sta te.To retur n to the or iginal p o- sition, simply en ter 0 in all thr ee in teger numb er fields under Rota te By. 40.6.3.3. Scaling O bjec ts To sc ale the selec ted objec t(s), enter the amoun t by which t o sc ale in each dir ection in the X,Y, and Z real numb er fields under Scale.To avoid dist ortion of the objec t’s shap e, be sur e to sp ecify the same v alue f or all thr ee en tries. Scaling is not cumula tive, so y ou c an easily r etur n to a k nown sta te. To retur n the objec t to its or iginal siz e, simply en ter 1 in all thr ee r eal numb er fields . 2853Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Advanced Sc ene C omp osition40.6.3.4. Displa ying the Meridional View To displa y the mer idional view of the selec ted objec t(s), enable the Meridional option. This option is available only f or 3D mo dels . It is applic able t o cases with a defined axis of r otation and is esp ecially useful in turb omachiner y applic ations . The mer idional tr ansf ormation pr ojec ts the selec ted en tities on to a sur face of c onstan t angular c o- ordina te, .The r esultan t projec tion thus lies in an ( , ) plane wher e is in the dir ection of the r o- tation axis and is nor mal t o it. The v alue of used f or the pr ojec tion is tak en as tha t corresponding to the minimum ( , ) point of the en tity. 40.6.4. Modifying I so-V alues You c an use the abilit y to gener ate sur faces with in termedia te values b etween t wo isosur faces (with different iso values) t o cr eate snapshots of the r esults . If the sur faces ha ve contours , vectors, or pa thlines displa yed on them, ANSY S Fluen t will gener ate and displa y contours , vectors, or pa thlines on the in ter- media te sur faces tha t it cr eates. 40.6.4.1. Steps for Mo difying Iso-V alues You c an mo dify an isosur face’s iso value dir ectly b y selec ting it in the Names list in the Scene D escr ip- tion D ialog Box (p.3683 ) or indir ectly b y selec ting an objec t displa yed on the isosur face.Then click Iso- Value ... to op en the Iso-V alue D ialog Box (p.3688 ) (Figur e 40.55: The I so-V alue D ialog Box (p.2854 )) for the selec ted objec t. Note tha t this butt on is a vailable only if the geometr ic objec t selec ted in the Names list is an isosur face or an objec t on an isosur face (contour on an isosur face, for e xample); other wise it is gr ayed out. Figur e 40.55: The I so-V alue D ialo g Box In the Iso-V alue D ialog Box (p.3688 ), set the new iso value in the Value field , and click Apply . Contours , vectors, or pa thlines tha t were displa yed on the or iginal isosur face will b e displa yed f or the new iso- value . 40.6.5. Modifying P athline A ttribut es If you ar e creating anima tions of e xisting pa thlines , you ma y want to change the numb er of st eps used in the c omputa tion of the pa thlines .This enables y ou t o anima te pa thlines ad vancing thr ough the domain. To do so , selec t the pa thlines in the Names list in the Scene D escr iption D ialog Box (p.3683 ) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2854Displa ying G raphicsand then click Pathlines ... to op en the Pathline A ttribut es D ialog Box (p.3689 ) (Figur e 40.56: The P athline Attribut es D ialog Box (p.2855 )). Figur e 40.56: The P athline A ttribut es D ialo g Box In the Pathline A ttribut es D ialog Box (p.3689 ), set the new maximum numb er of st eps f or pa thline computa tion ( Max S teps). After y ou change the v alue and click Apply , the selec ted pa thline will b e recomput ed and r edrawn. 40.6.6. Deleting an O bjec t from the Sc ene If you ar e comp osing a c omple x sc ene with o verlays and find tha t you no longer w ant to keep one of the objec ts, it is p ossible t o delet e it without aff ecting an y of the other objec ts in the sc ene.The abilit y to delet e individual objec ts is esp ecially useful if y ou ha ve overlays on and y ou gener ate an unw anted objec t (for e xample , if y ou gener ate contours of the wr ong v ariable). You c an simply delet e the un- wanted objec t and c ontinue y our sc ene c omp osition, inst ead of star ting o ver fr om the b eginning . Note tha t it is also p ossible t o mak e objec ts temp orarily in visible , as descr ibed in Controlling Visibil- ity (p.2851 ). Objec t deletion is p erformed in the Scene D escr iption D ialog Box (p.3683 ) (Figur e 40.51: The Sc ene D e- scription D ialog Box (p.2849 )).To delet e an objec t from the sc ene, selec t it in the Names list and then click Delet e Geometr y.The selec ted name will disapp ear fr om the Names list, and the displa y will b e updated immedia tely. 40.6.7. Adding a B ounding F rame ANSY S Fluen t enables y ou t o add a b ounding fr ame ar ound y our displa yed domain. You ma y also include measur e mar kings on the b ounding fr ame t o indic ate the length, heigh t, and/or width of the domain, as sho wn in Figur e 40.57: Graphics D ispla y with B ounding F rame (p.2856 ). 2855Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Advanced Sc ene C omp ositionFigur e 40.57: Graphics D ispla y with B ounding F rame To add a b ounding fr ame t o your displa y, you will f ollow the pr ocedur e below: 1. Click Frame Options ... in the Scene D escr iption D ialog Box (p.3683 ) (Figur e 40.51: The Sc ene D escr iption Dialog Box (p.2849 )) to op en the Bounding F rame D ialog Box (p.3689 ) (Figur e 40.58: The B ounding F rame Dialog Box (p.2856 )). Figur e 40.58: The B ounding F rame D ialo g Box 2. Under Frame E xtents in the Bounding F rame D ialog Box (p.3689 ), selec t Domain or Displa y to indic ate whether the b ounding fr ame should enc ompass the domain e xtents or only the p ortion of the domain that is sho wn in the displa y. 3. In the Axes portion of the Bounding F rame D ialog Box (p.3689 ), specify the fr ame b oundar ies and meas- uremen ts to be sho wn in the displa y: •Indic ate the b ounding plane(s) (f or e xample , the x-z and y-z planes sho wn in Figur e 40.57: Graphics Displa y with B ounding F rame (p.2856 )) to be displa yed b y click ing on the whit e squar e on the appr opriate Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2856Displa ying G raphicsplane of the b ox sho wn under the Axes heading .You c an use an y of the mouse butt ons.The squar e will tur n red t o indic ate tha t the asso ciated b ounding plane will b e displa yed in the gr aphics windo w. •Specify wher e you w ould lik e to see the measur emen t annota tions b y click ing on the appr opriate edge of the b ox.The edge will tur n red t o indic ate tha t the mar kings will b e displa yed along tha t edge of the displa yed geometr y. Imp ortant If you ha ve trouble det ermining which squar e or edge c orresponds t o which lo cation in your domain, you c an easily find out b y displa ying one or t wo bounding planes t o get y our b earings .You c an then selec t the appr opriate objec ts to obtain the final displa y. 4. Click Displa y to up date the displa y with the cur rent settings . If you ar e not sa tisfied with the fr ame , repeat steps 2 and/or 3 and click Displa y again. 5. Onc e you ar e sa tisfied with the b ounding fr ame tha t is displa yed, click OK to close the Bounding F rame Dialog Box (p.3689 ) and sa ve the fr ame settings f or futur e displa ys. 6. If you w ant to include the b ounding fr ame in all subsequen t displa ys, enable the Draw Frame option in the Scene D escr iption D ialog Box (p.3683 ) and click Apply . If this option is not enabled , the b ounding box will app ear only in the cur rent displa y; it will not b e redispla yed when y ou gener ate a new displa y (unless y ou ha ve overlays enabled). The b ounding planes and axis annota tions will app ear in the Names list of the Scene D escr iption Dialog Box (p.3683 ), and y ou c an manipula te them in the same w ay as an y other geometr ic objec t in the displa y. For e xample , you c an use the Displa y Properties D ialog Box (p.3685 ) to change the fac e color of a b ounding plane or t o mak e it tr anspar ent (see Changing an O bjec t’s Displa y Properties (p.2850 )). 40.7. Anima ting G raphics To gener ate anima tions tha t progress fr om one sta tic view of the gr aphics displa y to the ne xt, you c an set up “key frames ” (individual sta tic images) using the Anima te Dialog Box (p.3674 ) (Figur e 40.59: The Anima te Dialog Box (p.2858 )). Results → Anima tions → Scene A nima tion Edit... 2857Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Anima ting G raphicsFigur e 40.59: The A nima te D ialo g Box You c an c omp ose a sc ene in the gr aphics windo w and define it as a single k ey frame .Then, mo dify the scene b y mo ving or sc aling objec ts, mak ing some objec ts in visible or visible , changing c olors , changing the view , or mak ing other changes , and define the new sc ene as another k ey frame . ANSY S Fluen t can then in terpolate smo othly b etween the t wo frames tha t you defined , creating a sp ecified numb er of intermedia te frames . If you w ant to cr eate a gr aphic al anima tion of the solution o ver time , you c an use Figur e 37.41: The Anima tion D efinition D ialog Box (p.2671 ) to set up the gr aphic al displa ys tha t you w ant to use in the anima tion. You c an cho ose the t ype of displa y you w ant to anima te by selec ting it fr om the Anima tion Objec t list or b y creating a new anima tion objec t. For details on anima ting the solution, see Anima ting the S olution (p.2670 ). For mor e inf ormation on gener ating , displa ying , and sa ving pa thlines and par ticle tracks , refer to Displa ying P athlines (p.2802 ). See Displa ying R esults on a S weep Sur face (p.2813 ) for inf orm- ation ab out displa ying the mesh, contours , or v ectors on a sur face tha t sw eeps thr ough the domain. Note "Key frame" anima tions cr eated thr ough the Anima te dialo g box are not c ompa tible with iso-sur faces. For additional inf ormation, see the f ollowing sec tions: 40.7.1. Creating an A nima tion 40.7.2. Playing an A nima tion 40.7.3. Saving an A nima tion 40.7.4. Reading an A nima tion F ile 40.7.5. Notes on A nima tion 40.7.1. Creating an A nima tion You c an define an y numb er of k ey frames (up t o 3000) t o cr eate your anima tion. By assigning the ap- propriate numb ers t o the k ey frames , you pr ovide the inf ormation ANSY S Fluen t needs t o cr eate the Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2858Displa ying G raphicscorrect numb er of in termedia te frames . For e xample , to cr eate a simple anima tion tha t begins with a front view of an objec t, mo ves to a side view , and ends with a r ear view of the objec t, you w ould f ollow the pr ocedur e outlined b elow: 1. Determine the numb er of fr ames tha t you w ant in the anima tion. For this e xample , consider the anima tion to be 31 fr ames . 2. Determine the numb er of k ey frames tha t you need t o sp ecify . In this e xample , you will sp ecify thr ee: one sho wing the fr ont view , one sho wing the side view , and one sho wing the r ear view . 3. Determine the appr opriate key frame numb ers t o assign t o the 3 sp ecified fr ames . Here, the fr ont view will b e sp ecified as k ey frame 1, the side view will b e key frame 16, and the r ear view will b e key frame 31. 4. Comp ose the sc enes f or each view t o be used as a k ey frame .You c an use the Scene D escr iption D ialog Box (p.3683 ) (see Advanced Sc ene C omp osition (p.2848 )) and the Views Dialog Box (p.3690 ) (see Modifying the View (p.2835 )) to mo dify the displa y, and an y other dialo g boxes or c ommands t o create contours , vectors, pathlines , and so on t o be included in each sc ene. After you c omplet e each sc ene, create the appr opriate key frame b y setting the Frame numb er and click ing Add under Key Frames in the Anima te Dialog Box (p.3674 ). For sp ecial c onsider ations r elated t o key frame definition, see Notes on A nima- tion (p.2862 ). Imp ortant Be sur e to change the Frame numb er b efore click ing Add, or y ou will o verwrite the last k ey frame tha t you cr eated. You c an check an y of the k ey frames tha t you ha ve created b y selec ting it in the Keys list. The selec ted k ey frame will b e displa yed in the gr aphics windo w. 5. When y ou c omplet e the anima tion, you c an pla y it back as descr ibed in Playing an A nima tion (p.2859 ) and/or sa ve it as descr ibed in Saving an A nima tion (p.2861 ). 40.7.1.1. Deleting K ey Frames If, dur ing the cr eation of y our anima tion, you w ant to delet e one of the k ey frames tha t you ha ve defined , selec t the k ey frame in the Keys list and click Delet e. If you w ant to delet e all k ey frames and star t over again, click Delet e All. 40.7.2. Playing an A nima tion Onc e you ha ve defined the k ey frames (as descr ibed in Creating an A nima tion (p.2858 )) or r ead in a previously cr eated anima tion file (as descr ibed in Reading an A nima tion F ile (p.2862 )), you c an pla y back the anima tion and ANSY S Fluen t will in terpolate between the fr ames tha t you sp ecified t o complet e the anima tion. To pla y the anima tion onc e thr ough fr om star t to finish, click the “play” butt on under the Playback heading in the Anima te Dialog Box (p.3674 ). (The butt ons func tion in a w ay similar t o those on a standar d video c assett e pla yer.“Play” is the sec ond butt on fr om the r ight—a single tr iangle p ointing to the r ight.) To pla y the anima tion back wards onc e, click the “play reverse ” butt on (the sec ond fr om the lef t—a single tr iangle p oint to the lef t). As the anima tion pla ys, the Frame scale sho ws the numb er of the fr ame tha t is cur rently displa yed, as w ell as its r elative position in the en tire anima tion. If, inst ead 2859Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Anima ting G raphicsof pla ying the c omplet e anima tion, you w ant to jump t o a par ticular k ey frame , mo ve the Frame slider bar t o the desir ed fr ame numb er, and the fr ame c orresponding t o the new fr ame numb er will b e dis- played in the gr aphics windo w. Additional options f or pla ying back anima tions ar e descr ibed b elow. Be sur e to check Notes on A nim- ation (p.2862 ) as w ell for imp ortant not es ab out pla ying back anima tions . 40.7.2.1. Playing B ack an E xcerpt You ma y sometimes w ant to pla y only one p ortion of a long anima tion. To do this , you c an mo dify the Start Frame and the End F rame under the Playback heading in the Anima te Dialog Box (p.3674 ). For e xample , if y our anima tion c ontains 50 fr ames , but y ou w ant to pla y only fr ames 20 t o 35, you can set Start Frame to 20 and End F rame to 35. When y ou pla y the anima tion, it will star t at frame 20 and finish a t frame 35. 40.7.2.2. "Fast-F orwarding" the A nimation You c an "fast-f orward" or "fast-r everse" the anima tion b y sk ipping some of the fr ames dur ing pla yback. To fast-f orward the anima tion, set the Incr emen t and click the fast-f orward butt on. If, for e xample , your Start Frame is 1, your End F rame is 15, and y our Incr emen t is 2, when y ou click the fast-f orward butt on (the last butt on on the r ight—t wo triangles p ointing t o the r ight), the anima tion will sho w frames 1, 3, 5, 7, 9, 11, 13 and 15. Clicking on the fast-r everse butt on (the first butt on on the lef t—t wo triangles p ointing t o the lef t) will sho w fr ames 15, 13, 11,...1. 40.7.2.3. Continuous A nimation If you w ant the pla yback of the anima tion t o repeat continuously , ther e ar e two options a vailable . •To continuously pla y the anima tion fr om b eginning t o end (or fr om end t o beginning , if you use one of the r everse pla y butt ons), selec t Auto Rep eat in the Playback M ode drop-do wn list in the Anima te Dialog Box (p.3674 ). •To pla y the anima tion back and f orth continuously , reversing the pla yback dir ection each time , selec t Auto Re verse in the Playback M ode drop-do wn list. To tur n off the c ontinuous pla yback, selec t Play Onc e in the Playback M ode list. This is the default setting . 40.7.2.4. Stopping the A nimation To stop the anima tion dur ing pla yback, click the "stop" butt on (the squar e in the middle of the playback c ontrol butt ons). If your anima tion c ontains v ery complic ated sc enes , ther e ma y be a sligh t dela y before the anima tion st ops. 40.7.2.5. Advancing the A nimation F rame b y Frame To ad vance the anima tion manually fr ame b y frame , use the thir d butt on fr om the r ight (a v ertical bar with a tr iangle p ointing t o the r ight). Each time y ou click this butt on, the ne xt frame will b e dis- played in the gr aphics windo w.To reverse the anima tion fr ame b y frame , use the thir d butt on fr om the lef t (a lef t-pointing tr iangle with a v ertical bar). Frame-b y-frame pla yback enables y ou t o freeze the anima tion a t points tha t are of par ticular in terest. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2860Displa ying G raphics40.7.3. Saving an A nima tion Onc e you ha ve created y our anima tion, you c an sa ve it in an y of the f ollowing f ormats: •Anima tion file c ontaining the k ey frame descr iptions •Picture files , each c ontaining a fr ame of the anima tion •MPEG file c ontaining each fr ame of the anima tion 40.7.3.1. Animation F ile You c an sa ve the k ey frame definitions t o a file tha t can b e read back in to ANSY S Fluen t (see Reading an A nima tion F ile (p.2862 )) when y ou w ant to repla y the anima tion. Since the anima tion file will c ontain only the k ey frame definitions , you must b e sur e tha t you ha ve a c ase and da ta file c ontaining the necessar y sur faces and other inf ormation r eferred t o by the k ey frame descr iptions . To wr ite an anima tion file , selec t Key Frames in the Write/Rec ord Format drop-do wn list in the An- imate Dialog Box (p.3674 ), and click Write.... In The S elec t File D ialog Box (p.569), specify the name of the file and sa ve it. 40.7.3.2. Picture File You c an also gener ate a pic ture file f or each fr ame in the anima tion. This f eature enables y ou t o sa ve your anima tion fr ames t o pic ture files used b y an e xternal anima tion pr ogram such as ImageM agick. To sa ve the anima tion as a pic ture file , follow these st eps: 1. Selec t Picture Files in the Write/Rec ord Format drop-do wn list in the Anima te Dialog Box (p.3674 ). 2. If nec essar y, click Picture Options ... to op en the Save Picture Dialog Box (p.3676 ) and set the appr opriate paramet ers f or sa ving the pic ture files . (If you ar e sa ving pic ture files f or use with ImageM agick, for e x- ample , you ma y want to selec t the windo w dump f ormat. See Windo w D umps (Linux S ystems Only) (p.650) for details .) Click Apply in the Save Picture Dialog Box (p.3676 ) to sa ve your mo dified settings . Imp ortant Do not click Save... in the Save Picture Dialog Box (p.3676 ).You will sa ve the pic ture files fr om the Anima te Dialog Box (p.3674 ) in the ne xt step. 3. In the Anima te Dialog Box (p.3674 ), click Write.... In The S elec t File D ialog Box (p.569), specify the filename and click OK to sa ve the files . (See Windo w D umps (Linux S ystems Only) (p.650) for inf ormation ab out specifying filenames tha t incr emen t aut oma tically as additional pic tures ar e sa ved.) ANSY S Fluen t will repla y the anima tion, saving each fr ame t o a separ ate file . 40.7.3.3. MP EG F ile It is also p ossible t o sa ve all of the fr ames of the anima tion in an MPEG file , which c an b e view ed using an MPEG dec oder such as mpeg_pla y. Saving the en tire anima tion t o an MPEG file will r equir e less disk spac e than st oring the individual windo w dump files (using the pic ture metho d), but the MPEG file will yield lo wer-qualit y images .To sa ve the anima tion t o an MPEG file , follow these st eps: 2861Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Anima ting G raphics1. Selec t MPEG in the Write/Rec ord Format drop-do wn list in the Anima te Dialog Box (p.3674 ). 2. In the Anima te Dialog Box (p.3674 ), click Write.... In The S elec t File D ialog Box (p.569), specify the filename , and click OK to sa ve the files . ANSY S Fluen t repla ys the anima tion and sa ves each fr ame t o a separ ate scr atch file; it then combines all of the files in to a single MPEG file . 40.7.4. Reading an A nima tion F ile If you ha ve sa ved the k ey frames defining an anima tion t o an anima tion file (as descr ibed in Saving an A nima tion (p.2861 )), you c an r ead tha t file back in a t a la ter time (or in diff erent session) and pla y the anima tion. Before reading in an anima tion file , be sur e tha t the cur rent case and da ta contain the surfaces and an y other inf ormation tha t the k ey frame descr iption r efers t o. To read an anima tion file , click Read ... in the Anima te Dialog Box (p.3674 ). In The S elec t File D ialog Box (p.569), specify the name of the file t o be read. 40.7.5. Notes on A nima tion When y ou ar e creating and pla ying back anima tions , not e the f ollowing: •For smo other anima tions , enable the Double Buff ering option in the Displa y Options D ialog Box (p.3681 ) (see Modifying the R ender ing Options (p.2831 )).This will r educ e scr een flick er dur ing gr aphics up dates. •When y ou ar e defining k ey frames , you must cr eate all geometr ic objec ts tha t will b e used in the anima tion before you cr eate an y key frames .You c annot cr eate a k ey frame using one set of geometr ic objec ts and then gener ate a new geometr y (such as a v ector plot) and include tha t in another k ey frame . Create all geometr ic objec ts first , and then use the Displa y Properties D ialog Box (p.3685 ) to control the visibilit y of the objec ts in each k ey frame (see Controlling Visibilit y (p.2851 )). •A single anima tion sequenc e can c ontain up t o 3000 k ey frames . •When y ou pla y back an anima tion, the c olor map used will b e the one tha t is cur rently ac tive,not the one that was ac tive dur ing “recording .” 40.8. Hist ogram and X Y Plots In addition t o the man y gr aphics t ools alr eady discussed , ANSY S Fluen t also pr ovides t ools tha t enable you t o gener ate XY plots and hist ograms of solution, file, profile , and r esidual da ta.You c an mo dify the colors , titles , legend , and axis and cur ve attribut es to cust omiz e your plots .The f ollowing sec tions descr ibe the X Y and hist ogram plotting f eatures in ANSY S Fluen t. 40.8.1. Plot Types 40.8.2. XY Plots of S olution D ata 40.8.3. XY Plots of F ile D ata 40.8.4. XY Plots of P rofiles 40.8.5. XY Plots of C ircumf erential A verages 40.8.6. XY Plot F ile F ormat 40.8.7. Residual P lots 40.8.8. Hist ograms 40.8.9. Modifying A xis A ttribut es 40.8.10. Modifying C urve Attribut es Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2862Displa ying G raphics40.8.1. Plot Types Data can b e plott ed in X Y (abscissa/or dina te) form or hist ogram f orm. Each f orm is descr ibed b elow. 40.8.1.1. XY Plots An XY (abscissa/or dina te) plot is a line and/or symb ol char t of da ta.Virtually an y defined v ariable or func tion is acc essible f or this t ype of plot. Further mor e, you ma y read in an e xternally-gener ated da ta file in or der t o compar e your r esults with e xperimen tal da ta.You c an also use the X Y-plot facilit y to plot out pr ofile da ta, the r esidual hist ories of v ariables , or the time hist ories if y ou ha ve a tr ansien t problem. ANSY S Fluen t provides t ools f or c ontrolling man y asp ects of the X Y plot , including back ground c olor , legend , and axis and cur ve attribut es.Figur e 40.60: Sample X Y Plot (p.2863 ) sho ws a sample X Y plot. Figur e 40.60: Sample X Y Plot To diff erentiate the da ta b eing displa yed, you c an cust omiz e the pa ttern, color and w eigh t of the data lines and the shap e, color , and siz e of the da ta mar kers. When an X Y plot is displa yed in the gr aphics windo w, you c an use the mouse-pr obe option, but all other func tions ar e inac tive for X Y plots . In addition, you c an use an y of the mouse butt ons t o mo ve and r esize the legend b ox. 40.8.1.2. Hist ograms A hist ogram plot is a bar char t of da ta. It is a r epresen tation of a fr equenc y of distr ibution b y means of rectangles of widths r epresen ting class in tervals and with ar eas pr oportional t o the c orresponding frequencies .When a hist ogram plot is displa yed in the gr aphics windo w, you c an use the mouse- probe, but all other func tions ar e inac tive for hist ogram plots .Figur e 40.61: Sample Hist ogram (p.2864 ) shows a sample hist ogram. 2863Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Hist ogram and X Y PlotsFigur e 40.61: Sample Hist ogram See Hist ogram R eports (p.2951 ) for inf ormation ab out pr inting hist ogram r eports. For mor e inf ormation on hist ogram plots , see Hist ograms (p.2875 ). 40.8.2. XY Plots of S olution D ata You c an pr oduce a v ery sophistic ated X Y plot b y using da ta fr om se veral zones , sur faces, or files and modifying the axis and cur ve attribut es. Using the c apabilit y for loading e xternal da ta files , you c an create plots tha t compar e your ANSY S Fluen t results with da ta fr om other sour ces.To get fur ther in- formation ab out the solution, you c an in vestiga te the fr equenc y of distr ibution of the da ta using a histogram (see Hist ograms (p.2875 )). 40.8.2.1. Steps for G ener ating S olution X Y Plots You c an cr eate an X Y plot of solution da ta using the Solution X Y Plot D ialog Box (p.3703 ) (Fig- ure 40.62: The S olution X Y Plot D ialog Box (p.2865 )). Named X Y plot definitions c an b e sa ved f or lat er use . See Creating and U sing C ont our P lot D efinitions (p.2792 ) for additional inf ormation on gr aphics objec t definitions . Results → Plots → XY Plot New... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2864Displa ying G raphicsFigur e 40.62: The S olution X Y Plot D ialo g Box The basic st eps f or gener ating a solution X Y plot ar e as f ollows: 1. Specify the v ariable(s) y ou ar e plotting: •To plot a v ariable on the y-axis as a func tion of p osition on the x-axis , enable the Position on X A xis option and cho ose the v ariable t o be plott ed on the y-axis in the Y Axis F unc tion drop-do wn list. Selec t a c ategor y from the upp er list and then cho ose the desir ed quan tity in the lo wer list. For an explana tion of the v ariables in the list , see Field F unction D efinitions (p.2959 ). •To plot a v ariable on the x-axis as a func tion of p osition on the y-axis , enable the Position on Y Axis option and cho ose the v ariable t o be plott ed on the x-axis in the X Axis F unc tion drop-do wn list. •To plot one v ariable as a func tion of another , turn off b oth the Position on X A xis and Position on Y Axis options and selec t the v ariables t o be plott ed in the X Axis F unc tion and Y Axis F unc tion drop-do wn lists . 2. Specify the plot dir ection: •To plot a v ariable as a func tion of p osition along a sp ecified dir ection v ector, selec t Direction Vector in the X Axis F unc tion or Y Axis F unc tion drop-do wn list (whiche ver is the p osition axis), and sp ecify the c omp onen ts of the dir ection v ector for plotting under Plot D irection .The p osition axis of the plot is indic ated b y the selec tion of Position on X A xis or Position on Y Axis.The p ositions plott ed will ha ve coordina te values tha t correspond t o the dot pr oduc t of the da ta coordina te vector with the plot dir ection v ector. For e xample , if you ar e plotting a v ariable a t the pr essur e outlet of the geometr y sho wn in Figur e 40.63: Geometr y Used f or X Y Plot (p.2867 ), you w ould sp ecify the Plot D ir- ection vector (1,0,0) sinc e you ar e interested in ho w the v ariable changes as a func tion of x.Fig- ure 40.64: Data P lotted a t Outlet U sing a P lot D irection of (1,0,0) (p.2867 ) sho ws the r esulting X Y plot. 2865Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Hist ogram and X Y Plots(If you sp ecified (0,1,0) as the plot dir ection, all v ariable v alues w ould b e plott ed a t the same p osition (see Figur e 40.65: Data P lotted a t Outlet U sing a P lot D irection of (0,1,0) (p.2868 )), because the y value is the same a t every point on the pr essur e outlet.) •It is also p ossible t o plot a v ariable as a func tion of p osition along the length of a sp ecified cur vilinear surface.The cur vilinear sur face must b e piec ewise linear and it c annot c ontain mor e than one closed curve, such as a c omplet e cir cle.To plot a v ariable in this w ay, selec t Curve Length in the X Axis Func tion or Y Axis F unc tion drop-do wn list (whiche ver is the p osition axis). Then sp ecify the plot direction along the sur face: to plot the v ariable along the dir ection of incr easing cur ve length, selec t Default under Plot D irection ; to plot the v ariable in the dir ection of decr easing sur face length, selec t Reverse .To check the dir ection in which the v ariable will b e plott ed along a sur face, selec t the sur face in the Surfaces list and click Show under Plot D irection . ANSY S Fluen t will displa y the selec ted sur face in the gr aphics windo w, mar king the star t of the sur face with a blue dot and the end of the sur face with a r ed dot. ANSY S Fluen t will also displa y arrows on the sur face sho wing the dir ection in which the v ariable will b e plott ed. Note When r unning the par allel v ersion of ANSY S Fluen t,Curve Length is only supp orted when the cur vilinear sur face is c ontained within a single par tition. 3. Choose the sur face(s) on which t o plot da ta in the Surfaces list. Note tha t if y ou ar e plotting a v ariable as a func tion of p osition along the length of a cur vilinear sur face, you c an selec t only one sur face in the Surfaces list. 4. Set an y of the options descr ibed b elow, or mo dify the a ttribut es of the ax es or cur ves as descr ibed in Modifying A xis A ttribut es (p.2877 ) and Modifying C urve Attribut es (p.2879 ). 5. Click Plot to gener ate the X Y plot in the ac tive gr aphics windo w. You c an use an y of the mouse butt ons t o annota te the X Y plot (see Adding Text to the G raphics Windo w (p.2821 )) or mo ve the plot legend fr om its default p osition in the upp er lef t corner of the graphics windo w. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2866Displa ying G raphicsFigur e 40.63: Geometr y Used f or X Y Plot Figur e 40.64: Data P lott ed a t Outlet U sing a P lot D irection of (1,0,0) 2867Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Hist ogram and X Y PlotsFigur e 40.65: Data P lott ed a t Outlet U sing a P lot D irection of (0,1,0) 40.8.2.2. Options for S olution X Y Plots The options men tioned in Steps f or G ener ating S olution X Y Plots (p.2864 ) include the f ollowing . •You c an include da ta fr om an e xternal file in the solution X Y plot t o compar e your r esults with e xper- imen tal da ta. •You c an also cho ose no de or c ell v alues t o be plott ed, and sa ve the plot da ta to a file . 40.8.2.2.1. Including E xternal D ata in the S olution X Y Plot To add e xternal da ta to your X Y plot f or c ompar ison with y our r esults , you must first ensur e tha t any external da ta files ar e in the f ormat descr ibed in XY Plot F ile F ormat (p.2874 ).You c an then load the file(s) b y click ing on the Load F ile... butt on and sp ecifying the file(s) t o be read in The S elec t File D ialog Box (p.569). Onc e a file has b een loaded , its title will app ear in the File D ata list. You c an choose the da ta file(s) t o be included in y our plot fr om the titles in this list. To remo ve a file fr om the File D ata list, selec t it and then click Free D ata. 40.8.2.2.2. Choosing N ode or C ell Values In ANSY S Fluen t you c an cho ose t o displa y the c omput ed c ell-c enter v alues or v alues tha t ha ve been interpolated t o the no des. By default , the Node Values option is tur ned on, and the in terpolated values ar e displa yed. If you pr efer to displa y the c ell v alues , turn the Node Values option off . Node- averaged da ta cur ves ma y be somewha t smo other than cur ves for c ell v alues . For fac e-only func tions (f or e xample ,Wall S hear S tress), the c ell v alues tha t are displa yed f or boundar y zone sur faces will ac tually b e the fac e values .These fac e values ar e mor e accur ate, as fac e- only func tions ar e comput ed on the fac es and not on the c ells. For these fac e-only func tions , the cell v alues on p ostpr ocessing sur faces will displa y the v alues in the c ell. For mor e inf ormation ab out cell v alues , see Cell Values (p.2959 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2868Displa ying G raphicsIf you ar e displa ying the X Y plot t o sho w the eff ect of a p orous medium or 2D fan b oundar y, to depic t a sho ck w ave, or t o sho w an y other disc ontinuities or jumps in the plott ed v ariable , you should use c ell v alues; if y ou use no de v alues in such c ases , the disc ontinuit y will b e smear ed b y the no de a veraging f or gr aphics and will not b e sho wn clear ly in the plot. 40.8.2.2.3. Saving the P lot D ata t o a F ile Onc e you ha ve gener ated an X Y plot , you ma y want to sa ve the plot da ta to a file .You c an r ead this file in to ANSY S Fluen t at a la ter time and plot it alone using the File X Y Plot D ialog Box (p.3708 ), as descr ibed in XY Plots of F ile D ata (p.2869 ), or add it t o a plot of solution da ta, as descr ibed ab ove. To sa ve the plot da ta to a file , enable the Write to File option in the Solution X Y Plot D ialog Box (p.3703 ).The Plot butt on will change t o the Write... butt on. Clicking on the Write... butt on will invoke The S elec t File D ialog Box (p.569), in which y ou c an sp ecify a name and sa ve a file c ontaining the plot da ta.The f ormat of this file is descr ibed in XY Plot F ile F ormat (p.2874 ). To sor t the sa ved plot da ta in or der of asc ending x-axis v alue , enable the Order P oints option in the Solution X Y Plot D ialog Box (p.3703 ) before you click Write....This option is a vailable only when the Write to File option is enabled . 40.8.3. XY Plots of F ile D ata You c an pr oduce XY plots using da ta contained in e xternal files .The File X Y Plot D ialog Box (p.3708 ) enables y ou t o displa y da ta read fr om e xternal files in an abscissa/or dina te plot f orm.The f ormat of the plot file is descr ibed in XY Plot F ile F ormat (p.2874 ). 40.8.3.1. Steps for G ener ating X Y Plots of D ata in E xternal F iles You c an cr eate an X Y plot of da ta contained in one or mor e external files using the File X Y Plot D ialog Box (p.3708 ) (Figur e 40.66: The F ile X Y Plot D ialog Box (p.2870 )). Results → Plots → File → Set U p... 2869Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Hist ogram and X Y PlotsFigur e 40.66: The F ile X Y Plot D ialo g Box The st eps f or gener ating a file X Y plot ar e as f ollows: 1. Click Load ... to selec t the file(s) y ou w ant to plot. Note tha t report files and .xy files ar e supp orted (see XY Plot F ile F ormat (p.2874 ) for inf ormation on the .xy file f ormat). As so on as the files ar e loaded , the cur ves (plots) ar e all added t o the Curve Inf ormation list. 2. Selec t the X and Y variables tha t you w ant plott ed (f or a r eport definition file) and/or sp ecify the da ta sets y ou w ant plott ed f or an .xy file. Selec ting/de-selec ting Y variables and D ata S ets adds or r emo ves them fr om the Curve Inf orm- ation list. 3. Modify legend names as needed .To mo dify a legend name: 1.Selec t a name in the Legend N ames list. 2.Enter the new name in the t ext en try box to the r ight of the Change L egend E ntry butt on. 3.Click Change L egend E ntry. 4. You c an c ontrol the app earance of the ax es and cur ves b y click ing Axes... or Curves.... 5. Click Plot to gener ate an X Y plot of the da ta list ed in the Curve Inf ormation list. 40.8.4. XY Plots of P rofiles ANSY S Fluen t enables t wo options f or gener ating X Y plots of da ta related t o boundar y pr ofiles . Using the Plot P rofile D ata D ialog Box (p.3711 ), you c an plot the or iginal da ta p oints fr om the pr ofile file y ou have read in to ANSY S Fluen t. Alternatively, you c an plot the v alues assigned t o the c ell fac es on the Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2870Displa ying G raphicsboundar y after the pr ofile file has b een in terpolated, by using the Plot In terpolated D ata D ialog Box (p.3711 ). Imp ortant Note tha t you must ha ve valid da ta when tr ying t o use the pr ofile plotting options . For mor e inf ormation ab out b oundar y pr ofiles , see Profiles (p.1051 ). 40.8.4.1. Steps for G ener ating P lots of P rofile D ata Onc e you ha ve read a pr ofile file , it is a vailable f or plotting b y using the Plot P rofile D ata D ialog Box (p.3711 ). Results → Plots → Profile D ata → Set U p... Figur e 40.67: The P lot P rofile D ata D ialo g Box The pr ocedur e for gener ating an X Y plot of the or iginal pr ofile da ta is as f ollows: 1. Selec t one of the pr ofiles y ou ha ve read fr om the Profile selec tion list. 2. Selec t a field of the pr ofile fr om the Y Axis F unc tion selec tion list. 3. Choose a v ariable against which y ou w ant to plot the field da ta, and selec t it fr om the X Axis F unc tion selec tion list. The a vailable v ariables will v ary dep ending on the pr ofile , and include x,y,z,r, and time . 4. Modify the a ttribut es of the ax es or cur ves as descr ibed in Modifying A xis A ttribut es (p.2877 ) and Modi- fying C urve Attribut es (p.2879 ). 5. Click Plot to gener ate an X Y plot of the pr ofile field da ta. 2871Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Hist ogram and X Y Plots40.8.4.2. Steps for G ener ating P lots of Int erp olat ed P rofile D ata To in terpolate a pr ofile y ou must first r ead a pr ofile file f or the c ase, and selec t a pr ofile field in a boundar y conditions dialo g box (for e xample , the Velocity Inlet D ialog Box (p.3540 )). After the flo w solution has b een initializ ed, the c ell fac e values of the b oundar y zone c an b e plott ed b y using the Plot In terpolated D ata D ialog Box (p.3711 ). Results → Plots → Interpolated D ata → Set U p... Figur e 40.68: The P lot In terpolated D ata D ialo g Box The pr ocedur e for gener ating an X Y plot of the in terpolated da ta is as f ollows: 1. Selec t a z one fr om the Zones selec tion list. Only the z ones f or which y ou ha ve set a pr ofile field as one or mor e of the par amet ers will b e available in this list. 2. Selec t a pr ofile-r elated par amet er of the z one fr om the Y Axis F unc tion selec tion list. The name of the paramet er will b e the same as tha t of the dr op-do wn list in the b oundar y condition dialo g box from which the pr ofile field w as selec ted. 3. Choose a v ariable against which y ou w ant to plot the field da ta, and selec t it fr om the X Axis F unc tion selec tion list. The a vailable v ariables ar e x,y, and (f or 3D c ases) z. 4. Modify the a ttribut es of the ax es or cur ves as descr ibed in Modifying A xis A ttribut es (p.2877 ) and Modi- fying C urve Attribut es (p.2879 ). 5. Click Plot to gener ate an X Y plot of the c ell fac e values on the b oundar y. 40.8.5. XY Plots of C ircumf erential A verages You c an also gener ate a plot of cir cumf erential a verages in ANSY S Fluen t.This enables y ou t o find the average v alue of a quan tity at several diff erent radial or axial p ositions in y our mo del. ANSY S Fluen t com- putes the a verage of the quan tity over a sp ecified cir cumf erential ar ea, and then plots the a verage against the r adial or axial c oordina te. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2872Displa ying G raphics40.8.5.1. Steps for G ener ating an X Y Plot of C ircumfer ential A verages You c an gener ate an X Y plot of cir cumf erential a verages in the r adial dir ection using the circum- avg-radial text command: plot → circum-avg-radial or y ou c an use the circum-avg-axial text command t o gener ate an a verage in the axial dir ection: plot → circum-avg-axial The pr ocedur e for gener ating an X Y plot of cir cumf erential a verages is as f ollows: 1. Specify the v ariable t o be averaged b y typing its name when ANSY S Fluen t prompts y ou f or averages of.You c an pr ess Enter to see a list of a vailable v ariables . 2. Choose the sur face on which t o plot da ta b y typing its name when ANSY S Fluen t prompts y ou f or on surface . Imp ortant Use the Mesh D ispla y Dialog Box (p.3239 ) to see a list of sur faces on which y ou c an plot da ta. Pressing Enter will not sho w a list of a vailable sur faces. 3. Specify the number of bands to be created.The default numb er of bands is 5. ANSY S Fluen t will cr eate cir cumf erential bands b y iso clipping the sp ecified sur face in to equal bands of r adial or axial c oordina te. An example of the iso-clips cr eated is sho wn in Figur e 40.69: Iso- Clips C reated F or C ircumf erential A veraging (p.2873 ).The r adial or axial c oordina te is der ived fr om the r otation axis of the Referenc e Zone specified in the Reference Values Task P age (p.3601 ). Figur e 40.69: Iso-C lips C reated F or C ircumf erential A veraging 2873Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Hist ogram and X Y PlotsANSY S Fluen t then c omput es the a verage of the v ariable f or each band using the ar ea-w eigh ted a v- erage descr ibed in Computing Sur face In tegrals of the Theor y Guide . Finally , it plots the a verage of the v ariable as a func tion of r adial or axial c oordina te.Figur e 40.70: XY Plot of C ircumf erential A ver- ages (p.2874 ) sho ws an e xample of an X Y plot of cir cumf erential a verages using r adial c oordina tes. Figur e 40.70: XY Plot of C ircumf erential A verages When the cir cumf erential a verage plot is gener ated, ANSY S Fluen t also cr eates a new sur face called radial-bands or axial-bands , which c ontains the iso-clips descr ibed ab ove (see Figur e 40.69: Iso- Clips C reated F or C ircumf erential A veraging (p.2873 )).You c an use this sur face to gener ate other X Y plots . For mor e inf ormation on the cr eation and manipula tion of sur faces, see Creating Sur faces and Cell R egist ers f or D ispla ying and R eporting D ata (p.2727 ). 40.8.5.2. Customizing the A ppear anc e of the P lot If you w ant to cust omiz e the app earance of the ax es or cur ves in a cir cumf erential a verage plot , you can sa ve the plot da ta to a file (using the plot-to-file text command , as descr ibed in XY Plot File F ormat (p.2874 )), read the file in to ANSY S Fluen t and plot it again (using the File X Y Plot D ialog Box (p.3708 ), as descr ibed in XY Plots of F ile D ata (p.2869 )), and then use the Axes D ialog Box (p.3717 ) and Curves D ialog Box (p.3720 ) (as descr ibed in Modifying A xis A ttribut es (p.2877 ) and Modifying C urve Attribut es (p.2879 )) to mo dify the app earance of the plot. To sa ve the plot da ta to a file , first use the plot-to-file text command t o sp ecify the name of the file . plot → file-set → plot-to-file Then gener ate the cir cumf erential a verage X Y plot as descr ibed ab ove. ANSY S Fluen t will displa y the plot in the gr aphics windo w, and also sa ve the plot da ta to the sp ecified file . 40.8.6. XY Plot F ile F ormat The X Y file f ormat read or wr itten b y ANSY S Fluen t includes the f ollowing inf ormation: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2874Displa ying G raphics•The title of the plot •The lab el for the abscissa and the or dina te •Cortex variables and pairs of abscissa/or dina te da ta for each cur ve in the plot The f ollowing sample file illustr ates the X Y file f ormat: (title "Velocity Magnitude") (labels "Position" "Velocity Magnitude") ((xy/key/label "pressure-inlet-8") (xy/key/visible? #t) (xy/line/pattern "--") 0.0000 230.097 0. 0625 160.551 0.1250 149.205 ... 0.5000 183.007 ) Similar t o the c ase file f ormat, par entheses b ound the v arious piec es of inf ormation in the f ormatted, ASCII file .The title (title " ") and lab els (labels " ") must b e first in the file , then each curve has inf ormation in the f orm ((cxvar value) x y x y x y...) , wher e ther e ma y be zero or mor e Cortex variables defined f or each cur ve. You do not ha ve to include C ortex variables t o imp ort your X Y da ta. For e xample , you ma y want to imp ort experimen tal da ta to compar e with the ANSY S Fluen t solution. The f ollowing e xample w ould use the default C ortex variables in the c ode t o define the da ta. After y ou imp ort the file in to ANSY S Fluen t, you c ould then use the Axes D ialog Box (p.3717 ) and the Curves D ialog Box (p.3720 ) to cust omiz e the X Y plot , as descr ibed in Modifying A xis A ttribut es (p.2877 ) and Modifying C urve Attribut es (p.2879 ). (title "Experiment, Run 11") (labels "X, m" "Cp") ( 0 1.5 1.5 1.3 3.2 1.5 5.1 1.2 ) 40.8.7. Residual P lots Residual hist ory can b e displa yed using an X Y plot. The abscissa of the plot c orresponds t o the numb er of it erations and the or dina te corresponds t o the lo g-sc aled r esidual v alues . To plot the cur rent residual hist ory, click Plot in the Residual M onit ors D ialog Box (p.3910 ). Solution → Monit ors → Residuals Edit... For additional inf ormation ab out using the Residual M onit ors D ialog Box (p.3910 ) to plot r esiduals , see Printing and P lotting R esiduals (p.2650 ). 40.8.8. Hist ograms Hist ograms c an b e displa yed in a gr aphics windo w using a bar char t (or pr inted in the c onsole windo w, as descr ibed in Hist ogram R eports (p.2951 )).The abscissa of the char t is the desir ed solution quan tity and the or dina te is the p ercentage of the t otal numb er of c ells. 2875Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Hist ogram and X Y Plots40.8.8.1. Steps for G ener ating Hist ogram P lots You c an cr eate a hist ogram plot of solution da ta using the Hist ogram D ialog Box (p.3707 ) (Fig- ure 40.71: The Hist ogram D ialog Box (p.2876 )). Results → Plots → Hist ogram Edit... Figur e 40.71: The Hist ogram D ialo g Box The st eps f or gener ating a hist ogram plot ar e as f ollows: 1. Choose the sc alar quan tity to be plott ed in the Hist ogram O f drop-do wn list. Selec t a c ategor y in the upp er list and then selec t the desir ed quan tity in the lo wer list. (See Field F unction D efinitions (p.2959 ) for an e xplana tion of the v ariables in the list.) 2. Set the numb er of da ta in tervals tha t will b e plott ed in the hist ogram in the Divisions field . By default ther e will b e 10 in tervals (“ bars ”) in the hist ogram plot t o finer in tervals, incr ease the numb er of Divisions . You ma y want to click Comput e to up date the Min and Max fields when y ou ar e trying t o decide ho w man y divisions t o plot. 3. Selec t the fac e or c ell z one under Zones for which y ou w ant results plott ed or pr inted. If all z ones ar e selec ted, then the en tire domain will b e plott ed.You c an also plot hist ograms based on the selec ted Zone Types. 4. Set the option descr ibed b elow, if desir ed, or mo dify the a ttribut es of the ax es or cur ves as descr ibed in Modifying A xis A ttribut es (p.2877 ) and Modifying C urve Attribut es (p.2879 ). 5. Click Plot to gener ate the hist ogram plot in the ac tive gr aphics windo w. 6. Click Print to pr int out y our hist ogram r esults on individual z ones , or the en tire domain. Similar ly, you can click Comput e to calcula te your hist ogram r esults on individual z ones , or the en tire domain. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2876Displa ying G raphics40.8.8.2. Options for Hist ogram P lots Other than the axis and cur ve attribut e controls men tioned in the pr ocedur e ab ove, the only option for hist ogram plotting is the abilit y to sp ecify a subr ange of v alues t o be plott ed. 40.8.8.2.1. Specifying the R ange of Values P lott ed By default , the r ange of v alues included in the hist ogram plot is aut oma tically set t o the r ange of values in the en tire domain f or the selec ted v ariable . If you w ant to focus in on a smaller r ange of values , you c an r estrict the r ange t o be displa yed. To manually set the r ange of v alues , turn off the Auto Range option in the Hist ogram D ialog Box (p.3707 ).The Min and Max fields will b ecome editable , and y ou c an en ter the new r ange of v alues to be plott ed.To sho w the default r ange a t an y time , click Comput e and the Min and Max fields will b e up dated. You c an also cho ose t o base the minimum and maximum v alues on the r ange of v alues on the se- lected sur faces, rather than in the en tire domain. To do this , turn off the Global R ange option in the Hist ogram D ialog Box (p.3707 ).The Min and Max values will b e up dated when y ou ne xt click Comput e. 40.8.9. Modifying A xis A ttribut es You c an mo dify the app earance of the X Y and par amet ers tha t control the lab els, scale, range , numb ers, and major and minor r ules . For each t ype of plot (solution X Y, file X Y, profile , residual, hist ogram, and so on), you c an set diff erent axis par amet ers in the Axes D ialog Box (p.3717 ) (Figur e 40.72: The A xes Dialog Box (p.2877 )). Note tha t the title f ollowing Axes in the dialo g box indic ates which plot en vironmen t you ar e changing (f or e xample , the Axes - S olution X Y Plot dialo g box controls par amet ers f or solution XY plots). Figur e 40.72: The A xes D ialo g Box 2877Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Hist ogram and X Y PlotsTo op en the Axes D ialog Box (p.3717 ) for a par ticular plot t ype, click Axes... in the appr opriate dialo g box (for e xample , the Solution X Y Plot,File X Y Plot,Plot P rofile D ata,Plot In terpolated D ata, or Residual M onit ors dialo g box). 40.8.9.1. Using the A xes D ialo g Box The Axes D ialog Box (p.3717 ) enables y ou t o indep enden tly c ontrol the char acteristics of the or dina te (y-axis) and abscissa ( x-axis) on an X Y plot or par amet ers f or one axis or the other , by following the procedur e below: 1. Choose the axis f or which y ou w ant to mo dify the a ttribut es b y selec ting X or Y under Axis. 2. Set the desir ed par amet ers. 3. Click Apply and then cho ose the other axis and r epeat the st eps, if desir ed. The changes t o the axis a ttribut es will app ear in the gr aphics windo w the ne xt time y ou gener ate a plot. 40.8.9.1.1. Changing the A xis L abel If you w ant to mo dify the lab el for the axis , you c an do so b y editing the Label text field in the Axes Dialog Box (p.3717 ). 40.8.9.1.2. Changing the F ormat of the D ata L abels You c an change the f ormat of the lab els tha t define the pr imar y da ta divisions on the ax es using the c ontrols under the Numb er F ormat heading in the Axes D ialog Box (p.3717 ). •To displa y the r eal v alue with an in tegral and fr actional par t (for e xample , 1.0000), selec t floa t in the Type drop-do wn list. You c an set the numb er of digits in the fr actional par t by changing the v alue of Precision . •To displa y the r eal v alue with a man tissa and e xponen t (for e xample , 1.0e-02), selec t exponen tial in the Type drop-do wn list. You c an define the numb er of digits in the fr actional par t of the man tissa in the Precision field . •To displa y the r eal v alue with either floa t or e xponen tial f orm, dep ending on the siz e of the numb er and the defined Precision , cho ose gener al in the Type drop-do wn list. 40.8.9.1.3. Choosing L ogarithmic or D ecimal Sc aling By default , decimal sc aling is used f or b oth ax es (e xcept f or the -axis in r esidual plots , which uses a log sc ale). If you w ant to change t o a lo garithmic sc ale, enable the Log option in the Axes D ialog Box (p.3717 ).To retur n to a decimal sc ale, turn off the Log option. Note tha t when y ou ar e using the logarithmic sc ale, the Range values ar e the e xponen ts; to sp ecify a lo garithmic r ange fr om 1 t o 10000, for e xample , you will sp ecify a minimum v alue of 1 and a maximum v alue of 4. 40.8.9.1.4. Resetting the R ange of the A xis By default , the e xtents of the axis will r ange fr om the minimum v alue plott ed t o the maximum v alue plott ed. If you w ant to change the r ange or e xtents of the axis , you c an do so b y tur ning off the Auto Range option in the Axes D ialog Box (p.3717 ) and setting the new Minimum and Maximum values f or the Range .This f eature is useful when y ou ar e gener ating a ser ies of plots and y ou w ant Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2878Displa ying G raphicsthe e xtents of one or b oth of the ax es to be the same , even if the r ange of plott ed v alues diff ers. For e xample , if y ou ar e gener ating plots of t emp erature on se veral diff erent wall z ones , you migh t want the minimum and maximum t emp erature on the -axis t o be the same in e very plot so tha t you c an easily c ompar e one plot with another .You w ould det ermine a t emp erature range tha t in- cludes the t emp eratures on all w alls, and use tha t as the r ange f or the -axis in each plot. 40.8.9.1.5. Contr olling the M ajor and M inor R ules ANSY S Fluen t enables y ou t o displa y major and/or minor r ules on the ax es. Major and minor r ules are the hor izontal or v ertical lines tha t mar k, respectively, the pr imar y and sec ondar y da ta divisions and span the whole plot windo w to pr oduce a “mesh. ”To add major or minor r ules t o the plot , enable the Major R ules or Minor R ules option. You c an then sp ecify a c olor and w eigh t for each t ype of rule. Under the Major R ules or Minor R ules heading , selec t the desir ed c olor f or the lines in the Color drop-do wn list and sp ecify the line thick ness in the Weigh t field . A line of w eigh t 1.0 is nor mally 1 pix el wide . A w eigh t of 2.0 w ould mak e the line t wice as thick (tha t is, 2 pix els wide). 40.8.10. Modifying C urve Attribut es The da ta cur ves in X Y plots and hist ograms c an b e represen ted b y an y combina tion of lines and mar kers.You c an mo dify the a ttribut es of the cur ves, including the pa tterns, weigh ts, and c olors of the lines , and the symb ols, sizes, and c olors of the mar kers. For each t ype of plot (solution X Y, file X Y, profile , residual, par amet ers in the Curves D ialog Box (p.3720 ) (Figur e 40.73: The C urves D ialog Box (p.2879 )). Note tha t the title f ollowing Curves in the dialo g box indic ates which plot en vironmen t you ar e changing (f or e xample , the Curves - S olution X Y Plot dialo g box controls cur ve par amet ers f or solution XY plots). Figur e 40.73: The C urves D ialo g Box To op en the Curves D ialog Box (p.3720 ) for a par ticular plot t ype, click Curves... in the appr opriate dialo g box (for e xample ,Solution X Y Plot,File X Y Plot,Plot P rofile D ata,Plot In terpolated D ata, or Residual M onit ors dialo g box). 40.8.10.1. Using the C urves D ialo g Box The Curves D ialog Box (p.3720 ) enables y ou t o indep enden tly c ontrol the char acteristics of each da ta curve in an X Y plot or par amet ers f or a cur ve, you will f ollow the pr ocedur e below: 2879Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Hist ogram and X Y Plots1. Specify the cur ve for which y ou w ant to mo dify the a ttribut es b y incr easing or decr easing the Curve # coun ter.The cur ves ar e numb ered sequen tially , star ting fr om 0. For e xample , if you w ere plotting flo w- field v alues on t wo sur faces, the first sur face would b e cur ve 0, and the sec ond , cur ve 1. If the plot contains only one cur ve, the Curve # is set t o 0 and is not editable . 2. Set the desir ed line and/or mar ker par amet ers as descr ibed b elow. 3. Click Apply and then cho ose another Curve # and r epeat the st eps, if desir ed. Your changes t o the cur ve attribut es will app ear in the gr aphics windo w the ne xt time y ou gener ate a plot. 40.8.10.1.1. Changing the Line St yle You c an c ontrol the pa ttern, color , and w eigh t of the line using the c ontrols under the Line S tyle heading: •To set the line pa ttern for the cur ve, cho ose one of the it ems in the Pattern drop-do wn list. Except f or center and phan tom lines , the list displa ys examples of the pa ttern choic es. A center line alt ernates a very long dash and a shor t dash and a phan tom line alt ernates a v ery long dash and a double shor t dash. Note tha t selec ting the sec ond it em in the dr op-do wn list , represen ted b y 4 shor t dashes , will r esult in a solid-line cur ve. Imp ortant If you do not w ant the da ta p oints to be connec ted b y an y type of line (tha t is, if y ou plan t o use just mar kers), selec t the “blank ” choic e, which is the first it em in the Pattern list. •To set the c olor of the line , pick one of the choic es in the Color drop-do wn list. •To define the line thick ness , set the v alue of Weigh t. A line w eigh t of 1.0 is nor mally 1 pix el wide . Therefore, a w eigh t of 2.0 w ould mak e the line t wice as thick (tha t is, 2 pix els wide). 40.8.10.1.2. Changing the M ark er St yle You c an c ontrol the symb ol, color , and siz e for the da ta mar ker using the c ontrols under the Marker Style heading: •To set the symb ol used t o mar k da ta, cho ose one of the it ems in the Symb ol drop-do wn list. The list displa ys examples of the symb ol choic es. For e xample , in plotting pr essur e-coefficien t da ta on the upp er and lo wer sur faces of an air foil, the symb ol /*\ (filled-in up ward-pointing tr iangle) c ould b e used f or the mar ker represen ting the upp er sur face da ta, and the symb ol \*/ (filled-in do wnw ard-pointing tr iangle) could b e used f or the mar ker represen ting the lo wer sur face da ta. Imp ortant If you do not w ant the da ta p oints to be represen ted b y mar kers (tha t is, if y ou plan to use just a line c onnec ting the da ta p oints), selec t the “blank ” choic e, which is the first it em in the Style list. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2880Displa ying G raphics•To set the c olor of the mar ker, pick one of the choic es in the Color drop-do wn list. •To define the siz e of the da ta mar ker, set the v alue of Size. A symb ol of siz e 1.0 is 3.0% of the heigh t of the displa y scr een, except f or the “.” symb ol, which is alw ays one pix el. 40.8.10.1.3. Previewing the C urve St yle To see wha t a par ticular setting will lo ok lik e in the plot , you c an pr eview it in the Sample windo w of the Curves D ialog Box (p.3720 ). A single mar ker and/or line will b e sho wn with the sp ecified st yle attribut es. 40.9. Turb omachiner y Postpr ocessing In addition t o the man y gr aphics t ools alr eady discussed , ANSY S Fluen t also pr ovides turb omachiner y- specific p ostpr ocessing f eatures tha t can b e acc essed onc e you ha ve defined the t opology of the problem. Information on p ostpr ocessing f or turb omachiner y applic ations is pr ovided in the f ollowing sections: 40.9.1. Defining the Turbomachiner y Topology 40.9.2. Gener ating R eports of Turbomachiner y Data 40.9.3. Displa ying Turbomachiner y Averaged C ontours 40.9.4. Displa ying Turbomachiner y 2D C ontours 40.9.5. Gener ating A veraged X Y Plots of Turbomachiner y Solution D ata 40.9.6. Globally S etting the Turbomachiner y Topology 40.9.7. Turbomachiner y-Specific Variables 40.9.1. Defining the Turb omachiner y Topology In or der t o establish the turb omachiner y-sp ecific c oordina te sy stem used in subsequen t postpr ocessing func tions , ANSY S Fluen t requir es y ou t o define the t opology of the flo w domain. The pr ocedur e for defining the t opology is descr ibed fur ther in this sec tion, along with details ab out the b oundar y types. The cur rent implemen tation of the turb omachiner y topology definition f or p ostpr ocessing is no longer limit ed t o one r ow of blades a t a time . If your geometr y contains multiple r ows of blades , you c an define all turb omachiner y topologies simultaneously .You c an name and/or manage all t opologies and perform v arious turb omachiner y postpr ocessing tasks on a single t opology or on all t opologies a t once. Imp ortant The turb o coordina tes c an only b e gener ated pr operly if the c orrect rotation axis is sp ecified in the b oundar y conditions dialo g box for the fluid z one (see Specifying the R otation A x- is (p.856)). To define the turb omachiner y topology in ANSY S Fluen t, you will use the Turbo Topology Dialog Box (p.3945 ) (Figur e 40.74: The Turbo Topology Dialog Box (p.2882 )). Domain → Mesh M odels → Turb o Topology... 2881Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Turbomachiner y Postpr ocessingFigur e 40.74: The Turb o Topology D ialo g Box The pr ocedur e for defining t opology for y our turb omachiner y applic ation ar e as f ollows: 1. Selec t a b oundar y type under Boundar ies (for e xample ,Hub in Figur e 40.74: The Turbo Topology Dialog Box (p.2882 )).The b oundar y types ar e descr ibed in detail in Boundar y Types (p.2883 ). 2. In the Surfaces list, cho ose the sur face(s) tha t represen t the b oundar y type you selec ted in st ep 1. If you w ant to selec t several sur faces of the same t ype, click and selec t Surface Type under Group B y, which or ganiz es the sur faces in a tr ee view tha t is gr oup ed b y sur face type. Another shor tcut is t o use the Filter Text entry box to filt er the Surfaces list t o sho w only the surfaces tha t ma tch the pa ttern you en ter. For additional inf ormation on using the Filter Text entry box, see Filter Text En try Boxes (p.565). 3. Repeat the st eps 1 and 2 f or all the b oundar y types tha t are relevant for y our mo del. Imp ortant For a c omplet e turb o topology definition the sur faces defined as inlet , outlet , hub , casing , periodic, theta min, and theta max (if a vailable) should f orm a closed domain. 4. Enter a name in the Turb o Topology Name field or k eep the default name . 5. Click Define to complet e the definition of the b oundar ies. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2882Displa ying G raphicsANSY S Fluen t will inf orm y ou tha t the turb omachiner y postpr ocessing func tions ha ve been ac tiv- ated. 6. Specify a p osition v ector tha t is defined as .This p osition v ector should b e outside the domain, for example , if your domain lies in the first and sec ond quadr ant, specify nega tive -axis as the z ero line . This will ensur e tha t ther e is no disc ontinuit y in angular c oordina tes within the domain. This c an b e done using the display/set/zero-angle-dir command . Default z ero line is -axis . If this axis passes thr ough the domain, you should define the z ero line , so as t o satisfy ab ove cr iteria. 7. To view a defined t opology, selec t the t opology from the Turb o Topology Name drop-do wn list and click Displa y.The defined t opology is sho wn in the ac tive gr aphics windo w.This enables y ou t o visually check the b oundar ies t o ensur e tha t you ha ve defined them c orrectly. 8. To edit a defined t opology, selec t the t opology from the Turb o Topology Name drop-do wn list , mak e the appr opriate changes and click Modify . 9. To remo ve a defined t opology, selec t the t opology from the Turb o Topology Name drop-do wn list and click Delet e. Imp ortant Note tha t the t opology setup tha t you define will b e sa ved t o the c ase file when y ou sa ve the cur rent mo del. Thus, if y ou r ead this c ase back in to ANSY S Fluen t, you do not need t o set up the t opology again. However, use of a b oundar y condition file t o set the turb o topology for two similar c ases ma y not work pr operly. In tha t case y ou need t o set the turb o topology manually . 40.9.1.1. Boundar y Types The b oundar ies f or the turb omachiner y topology are as f ollows (see Figur e 40.75: Turbomachiner y Boundar y Types (p.2884 )): Hub is the w all z one(s) f orming the lo wer b oundar y of the flo w passage (gener ally t oward the axis of r otation of the machine). Casing is the w all z one(s) f orming the upp er b oundar y of the flo w passage (a way from the axis of r otation of the machine). Theta P eriodic is the p eriodic b oundar y zone(s) on the cir cumf erential b oundar ies of the flo w passage . Theta M in and Theta M ax are the w all z ones a t the minimum and maximum angular ( ) positions on a cir cumf er- ential b oundar y. Inlet is the inlet z one(s) thr ough which the flo w en ters the passage . 2883Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Turbomachiner y Postpr ocessingOutlet is the outlet z one(s) thr ough which the flo w exits the passage . Blade is the w all z one(s) tha t defines the blade(s) (if an y). Note tha t these z ones c annot b e attached t o the circumf erential b oundar ies. For this situa tion, use Theta M in and Theta M ax to define the blade . Figur e 40.75: Turb omachiner y Boundar y Types 40.9.2. Gener ating Rep orts of Turb omachiner y Data Onc e you ha ve defined y our turb omachiner y topologies , as descr ibed in Defining the Turbomachiner y Topology (p.2881 ), you c an r eport a numb er of turb omachiner y quan tities , including mass flo w, swir l numb er, torque , and efficiencies . To report turb omachiner y quan tities in ANSY S Fluen t, you will use the Turbo Report Dialog Box (p.3943 ) (Figur e 40.76: The Turbo Report Dialog Box (p.2885 )). Results → Model S pecific → Turb o Topology → Rep ort... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2884Displa ying G raphicsFigur e 40.76: The Turb o Rep ort Dialo g Box The pr ocedur e for using this dialo g box is as f ollows: 1. Under Averages , specify whether y ou w ant to report Mass-W eigh ted or Area-W eigh ted averages . 2. Under Turb o Topology, specify a pr edefined turb omachiner y topology from the dr op-do wn list. 3. Click Comput e. ANSY S Fluen t will c omput e the turb omachiner y quan tities as descr ibed b elow, and displa y their v alues . 4. If you w ant to sa ve the r eported v alues t o a file , click Write... and sp ecify a name f or the file in The S elec t File D ialog Box (p.569). 40.9.2.1. Computing Turb omachiner y Q uantities 40.9.2.1.1. Mass F low The mass flo w rate thr ough a sur face is defined as f ollows: (40.2) wher e = is the ar ea of the inlet or outlet = the v elocity vector = the fluid densit y 2885Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Turbomachiner y Postpr ocessing = a unit v ector nor mal t o the sur face 40.9.2.1.2. Swirl Numb er The swir l numb er is defined as f ollows: (40.3) wher e = the r adial c oordina te (sp ecific ally, the r adial distanc e from the axis of r otation) = the tangen tial v elocity = the v elocity vector = a unit v ector nor mal t o the sur face, = the inlet or outlet 40.9.2.1.3. Average Total P ressur e The ar ea-a veraged t otal pr essur e is defined as f ollows: (40.4) wher e is the t otal pr essur e and is the ar ea of the inlet or outlet. The mass-a veraged t otal pr essur e is defined as f ollows: (40.5) wher e, = the t otal pr essur e = the ar ea of the inlet or outlet = the v elocity vector = the fluid densit y = a unit v ector nor mal t o the sur face 40.9.2.1.4. Average Total Temp eratur e The ar ea-a veraged t otal t emp erature is defined as f ollows: (40.6) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2886Displa ying G raphicswher e is the t otal t emp erature and is the ar ea of the inlet or outlet. The mass-a veraged t otal t emp erature is defined as f ollows: (40.7) wher e, = the t otal t emp erature = the ar ea of the inlet or outlet = the v elocity vector = the fluid densit y = a unit v ector nor mal t o the sur face 40.9.2.1.5. Average F low A ngles The ar ea-a veraged flo w angles ar e defined as f ollows: (40.8) in the r adial dir ection, and (40.9) in the tangen tial dir ection, wher e , , and represen t the axial, radial, and tangen tial v elocities , respectively. The mass-a veraged flo w angles ar e defined as f ollows: (40.10) in the r adial dir ection, and (40.11) in the tangen tial dir ection. 40.9.2.1.6. Passage L oss C oefficient The engineer ing loss c oefficien t is defined as f ollows: 2887Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Turbomachiner y Postpr ocessing(40.12) wher e, = the mass-a veraged t otal pr essur e at the inlet = the mass-a veraged t otal pr essur e at the outlet = the densit y of the fluid = the mass-a veraged v elocity magnitude a t the inlet The nor maliz ed loss c oefficien t is defined as f ollows: (40.13) wher e is the mass-a veraged sta tic pr essur e at the outlet. 40.9.2.1.7. Axial F orce The axial f orce on the r otating par ts is defined as f ollows: (40.14) wher e, = the sur faces c ompr ising all r otating par ts = the t otal str ess t ensor (pr essur e and visc ous str esses) = a unit v ector nor mal t o the sur face = a unit v ector par allel t o the axis of r otation 40.9.2.1.8. Torque The t orque on the r otating par ts is defined as f ollows: (40.15) wher e, = the sur faces c ompr ising all r otating par ts = the t otal str ess t ensor = a unit v ector nor mal t o the sur face = the p osition v ector = a unit v ector par allel t o the axis of r otation 40.9.2.1.9. Efficiencies for P umps and C ompr essors The definitions of the efficiencies f or c ompr essible and inc ompr essible flo ws in pumps and c om- pressors ar e descr ibed in this sec tion. Efficiencies f or turbines ar e descr ibed la ter in this sec tion. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2888Displa ying G raphicsConsider a pumping or c ompr ession de vice op erating b etween sta tes 1 and 2 as illustr ated in Fig- ure 40.77: Pump or C ompr essor (p.2889 ).Work input t o the de vice is r equir ed t o achie ve a sp ecified compr ession of the w orking fluid . Figur e 40.77: Pump or C ompr essor Assuming tha t the pr ocesses ar e steady sta te, steady flo w, and tha t the mass flo w rates ar e equal at the inlet and outlet of the de vice (no film c ooling , bleed air r emo val, and so on), the efficiencies for inc ompr essible and c ompr essible flo ws are as descr ibed in the f ollowing subsec tions . 40.9.2.1.9.1. Inc ompr essible F lows For de vices such as liquid pumps and fans (2D b oundar ies or 3D c ell z ones) a t low sp eeds , the working fluid c an b e treated as inc ompr essible .The efficienc y of a pumping pr ocess with an inc om- pressible w orking fluid is defined as the r atio of the head r ise achie ved b y the fluid t o the p ower supplied t o the r otor/imp eller .This c an b e expressed as f ollows: (40.16) wher e, = v olumetr ic flo w rate = total pr essur e = net t orque ac ting on the r otor/imp eller = rotational sp eed This definition is sometimes c alled the “hydraulic efficienc y”. Often, other efficiencies ar e included to acc oun t for flo w leak age (v olumetr ic efficienc y) and mechanic al losses along the tr ansmission system b etween the r otor and the machine pr oviding the p ower for the r otor/imp eller (mechanic al efficienc y). Incorporating these losses then yields a t otal efficienc y for the sy stem. 40.9.2.1.9.2. Compr essible F lows For gas c ompr essors tha t op erate at high sp eeds and high pr essur e ratios, the c ompr essibilit y of the working fluid must b e tak en in to acc oun t.The efficienc y of a c ompr ession pr ocess with a c ompr essible working fluid is defined as the r atio of the w ork requir ed f or an ideal (r eversible) c ompr ession pr ocess to the ac tual w ork input. This assumes the c ompr ession pr ocess o ccurs b etween sta tes 1 and 2 for a giv en pr essur e ratio . In most c ases , the pr essur e ratio is the total pr essur e at stat e 2 divided b y the total pr essur e at stat e 1. If the pr ocess is also adiaba tic, then the ideal sta te at 2 is the isentr opic state. 2889Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Turbomachiner y Postpr ocessingFrom the f oregoing definition, the efficienc y for an adiaba tic c ompr ession pr ocess c an b e wr itten as (40.17) wher e, = total en thalp y at 1 = ac tual t otal en thalp y at 2 = isen tropic t otal en thalp y at 2 If the sp ecific hea t is c onstan t,Equa tion 40.17 (p.2890 ) can also b e expressed as (40.18) wher e, = total t emp erature at 1 = ac tual t otal t emp erature at 2 = isen tropic t otal t emp erature at 2 Using the isen tropic r elation (40.19) wher e is the r atio of sp ecific hea ts sp ecified in the Reference Values Task P age (p.3601 ). The efficienc y can b e wr itten in the c ompac t form (40.20) Note tha t this definition r equir es da ta only f or the actual states 1 and 2. Compr essor designers also mak e use of the p olytr opic efficienc y when c ompar ing one c ompr essor with another .The p olytr opic efficienc y is defined as f ollows: (40.21) 40.9.2.1.10. Efficiencies for Turbines Consider a turbine op erating b etween sta tes 1 and 2 in Figur e 40.78: Turbine (p.2891 ).Work is e xtracted from the w orking fluid as it e xpands thr ough the turbine . Assuming tha t the pr ocesses ar e steady state, steady flo w, and tha t the mass flo w rates ar e equal a t the inlet and outlet of the de vice (no film c ooling , bleed air r emo val, and so on), turbine efficiencies f or inc ompr essible and c ompr essible flows are as descr ibed b elow. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2890Displa ying G raphicsFigur e 40.78: Turbine 40.9.2.1.10.1. Inc ompr essible F lows The efficienc y of a turbine with an inc ompr essible w orking fluid is defined as the r atio of the w ork deliv ered t o the r otor to the ener gy available fr om the fluid str eam. This r atio c an b e expressed as follows: (40.22) wher e, = v olumetr ic flo w rate = total pr essur e = net t orque ac ting on the r otor/imp eller = rotational sp eed Note the similar ity between this definition and the definition of inc ompr essible c ompr ession efficienc y (Equa tion 40.16 (p.2889 )). As with h ydraulic pumps and c ompr essors , other efficiencies (f or e xample , volumetr ic and mechanic al efficiencies) c an b e defined t o acc oun t for other losses in the sy stem. 40.9.2.1.10.2. Compr essible F lows For high-sp eed gas turbines op erating a t lar ge e xpansion pr essur e ratios, compr essibilit y must b e accoun ted f or.The efficienc y of an e xpansion pr ocess with a c ompr essible w orking fluid is defined as the r atio of the ac tual w ork extracted fr om the fluid t o the w ork extracted fr om an ideal (r eversible) process.This assumes tha t the e xpansion pr ocess o ccurs b etween sta tes 1 and 2 for a giv en pr essur e ratio . In c ontrast t o the c ompr ession pr ocess, the pr essur e ratio f or e xpansion is the total pr essur e at stat e 1 divided b y the total pr essur e at stat e 2. If the pr ocess is also adiaba tic, then the ideal sta te at 2 is the isentr opic state. From the f oregoing definition, the efficienc y for an adiaba tic e xpansion pr ocess thr ough a turbine can b e wr itten as (40.23) wher e = total en thalp y at 1 2891Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Turbomachiner y Postpr ocessing = ac tual t otal en thalp y at 2 = isen tropic t otal en thalp y at 2 If the sp ecific hea t is c onstan t,Equa tion 40.23 (p.2891 ) can also b e expressed as (40.24) wher e = total t emp erature at 1 = ac tual t otal t emp erature at 2 = isen tropic t otal t emp erature at 2 Using the isen tropic r elation (40.25) the e xpansion efficienc y can b e wr itten in the c ompac t form (40.26) Note tha t this definition r equir es da ta only f or the actual states 1 and 2. As with c ompr essors , one ma y also define a p olytr opic efficienc y for turbines .The p olytr opic efficienc y is defined as f ollows: (40.27) 40.9.3. Displa ying Turb omachiner y Averaged C ontours Turbo averaged c ontours ar e gener ated as pr ojec tions of the v alues of a v ariable a veraged in the cir- cumf erential dir ection and visualiz ed on an - plane . A sample plot is sho wn in Figur e 40.80: Turbo Averaged F illed C ontours of S tatic P ressur e (p.2894 ). 40.9.3.1. Steps for G ener ating Turb omachiner y Averaged C ont our P lots You c an displa y contours using the Turbo Averaged C ontours D ialog Box (p.3939 ) (Figur e 40.79: The Turbo Averaged C ontours D ialog Box (p.2893 )). Results → Model S pecific → Turb o Topology → Averaged C ontours ... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2892Displa ying G raphicsFigur e 40.79: The Turb o Averaged C ontours D ialo g Box The basic st eps f or gener ating a turb o averaged c ontour plot ar e as f ollows: 1. Selec t All or a sp ecific pr edefined turb omachiner y topology from the Turb o Topology drop-do wn list. 2. Selec t the v ariable or func tion t o be displa yed in the Contours of drop-do wn list. First selec t the desir ed categor y in the upp er list; you ma y then selec t a r elated quan tity in the lo wer list. (See Turbomachiner y- Specific Variables (p.2897 ) for a list of turb omachiner y-sp ecific v ariables , and see Field F unction D efini- tions (p.2959 ) for an e xplana tion of the v ariables in the list.) 3. Specify the numb er of c ontours in the Levels field .The maximum numb er of le vels allo wed is 100. 4. Set an y of the options descr ibed b elow. 5. Click Displa y to dr aw the sp ecified c ontours in the ac tive gr aphics windo w. The r esulting displa y will include the sp ecified numb er of c ontours of the selec ted v ariable , with the magnitude on each one det ermined b y equally incr emen ting b etween the v alues sho wn in the Min and Max fields . Note tha t the Min and Max values displa yed in the dialo g box are the minimum and maximum a ver- aged v alues .These limits will in gener al b e diff erent from the global Domain M in and Domain M ax, which ar e also displa yed f or y our r eference (see Figur e 40.79: The Turbo Averaged C ontours D ialog Box (p.2893 )). 2893Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Turbomachiner y Postpr ocessingFigur e 40.80: Turb o Averaged F illed C ontours of S tatic P ressur e 40.9.3.2. Cont our P lot O ptions The options men tioned in the pr ocedur e ab ove include dr awing c olor-filled c ontours (inst ead of line contours), specifying a r ange of v alues t o be contoured, and st oring the c ontour plot settings .These options ar e the same as those in the standar d Contours D ialog Box (p.3790 ). See Contour and P rofile Plot Options (p.2788 ) for details ab out using them. 40.9.4. Displa ying Turb omachiner y 2D C ontours In p ostpr ocessing a turb omachiner y solution, it is of ten desir able t o displa y contours on sur faces of constan t spanwise c oordina te, and then pr ojec t these c ontours on to a plane .This p ermits easier evalua tion of the c ontours , esp ecially f or sur faces tha t are highly thr ee-dimensional. 40.9.4.1. Steps for G ener ating Turb o 2D C ont our P lots You c an displa y contours using the Turbo 2D C ontours D ialog Box (p.3938 ) (Figur e 40.81: The Turbo 2D C ontours D ialog Box (p.2895 )). Results → Model S pecific → Turb o Topology → 2D C ontours ... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2894Displa ying G raphicsFigur e 40.81: The Turb o 2D C ontours D ialo g Box The basic st eps f or gener ating a turb o 2D c ontour plot ar e as f ollows: 1. Specify a sp ecific pr edefined turb omachiner y topology using the Turb o Topology drop-do wn list. 2. Enter a v alue f or the Normaliz ed S panwise C oordina tes (0 t o 1) for the spanwise sur face you w ant to create. Imp ortant If shr oud and hub ar e the cur ved sur faces, the isosur face very close t o them ma y contain v oid spac es as ANSY S Fluen t displa ys only a plane cut sur face. 3. Selec t the v ariable or func tion t o be displa yed in the Contours of drop-do wn list. First selec t the desir ed c ategor y in the upp er list; you ma y then selec t a r elated quan tity in the lower list. See Turbomachiner y-Specific Variables (p.2897 ) for a list of turb omachiner y-sp ecific variables , and see Field F unction D efinitions (p.2959 ) for an e xplana tion of the v ariables in the list. 4. Specify the numb er of c ontours in the Levels field .The maximum numb er of le vels allo wed is 100. 5. Click Displa y to dr aw the sp ecified c ontours in the ac tive gr aphics windo w. The r esulting displa y will include the sp ecified numb er of c ontours of the selec ted v ariable , with the magnitude on each one det ermined b y equally incr emen ting b etween the v alues sho wn in the Min and Max fields . 2895Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Turbomachiner y Postpr ocessing40.9.4.2. Cont our P lot O ptions Depending on the t ype of c ontour plot y ou w ant to displa y, selec t appr opriate choic e under Options . These options ar e the same as those in the standar d Contours D ialog Box (p.3790 ). See Contour and Profile P lot Options (p.2788 ) for details ab out using them. 40.9.5. Gener ating A veraged X Y Plots of Turb omachiner y Solution D ata When c ompar ing numer ical solutions of turb omachiner y pr oblems t o experimen tal da ta, it is of ten useful t o plot cir cumf erentially a veraged quan tities in the spanwise and mer idional dir ections .This section descr ibes ho w to do this in ANSY S Fluen t. 40.9.5.1. Steps for G ener ating Turb o Averaged X Y Plots To cr eate an X Y plot of cir cumf erentially a veraged solution da ta, you will use the Turbo Averaged X Y Plot D ialog Box (p.3941 ) (Figur e 40.82: The Turbo Averaged X Y Plot D ialog Box (p.2896 )). Results → Model S pecific → Turb o Topology → Averaged X Y Plot... Figur e 40.82: The Turb o Averaged X Y Plot D ialo g Box The pr ocedur e for gener ating a turb o averaged X Y plot ar e as f ollows: 1. Selec t the v ariable or func tion t o be plott ed in the Y Axis F unc tion drop-do wn list. First selec t the desir ed categor y in the upp er list; you ma y then selec t a r elated quan tity in the lo wer list. (See Turbomachiner y- Specific Variables (p.2897 ) for a list of turb omachiner y-sp ecific v ariables , and see Field F unction D efini- tions (p.2959 ) for an e xplana tion of the v ariables in the list.) 2. Selec t All or a sp ecific pr edefined turb omachiner y topology from the Turb o Topology drop-do wn list. 3. Selec t the v ariable or func tion t o be plott ed in the X Axis F unc tion drop-do wn list. The choic es ar e Hub t o Casing D istanc e and Meridional D istanc e. 4. Specify the desir ed v alue in the Fractional D istanc e field .The definition of the fr actional distanc e de- pends on y our selec tion of X Axis F unc tion : Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2896Displa ying G raphics•If you selec t Hub t o Casing D istanc e, the fr actional distanc e will b e Inlet t o Outlet . •If you selec t Meridional D istanc e, the fr actional distanc e will b e Hub t o Casing . 5. (optional) M odify the a ttribut es of the ax es or cur ves as descr ibed in Modifying A xis A ttribut es (p.2877 ) and Modifying C urve Attribut es (p.2879 ). 6. Click Plot to gener ate the X Y plot in the ac tive gr aphics windo w. Note tha t you c an use an y of the mouse butt ons t o annota te the X Y plot (see Adding Text to the G raphics Windo w (p.2821 )). If you w ant to wr ite the X Y da ta to a file , follow these st eps inst ead of S tep 5 ab ove: 1. Enable the Write to File option. The Plot butt on changes t o a Write... butt on. 2. Click Write.... 3. In The S elec t File D ialog Box (p.569), specify a name f or the plot file and sa ve it. 40.9.6. Globally S etting the Turb omachiner y Topology In some c ases , tha t is, isosur face creation, ANSY S Fluen t enables y ou t o globally set the cur rent tur- bomachiner y topology for y our mo del using the Turbo Options D ialog Box (p.3942 ) (Figur e 40.83: The Turbo Options D ialog Box (p.2897 )). Results → Model S pecific → Turb o Topology → Options ... Figur e 40.83: The Turb o Options D ialo g Box To set the cur rent topology, selec t a t opology from the Current Topology drop-do wn list and selec t OK. 40.9.7. Turb omachiner y-Specific Variables The f ollowing turb omachiner y-sp ecific v ariables ar e available in ANSY S Fluen t: •Meridional C oordina te •Abs M eridional C oordina te •Spanwise C oordina te 2897Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Turbomachiner y Postpr ocessing•Abs (H-C) S panwise C oordina te •Abs (C-H) S panwise C oordina te •Pitchwise C oordina te •Abs P itchwise C oordina te These v ariables ar e contained in the Mesh... categor y of the v ariable selec tion dr op-do wn list. See Field F unction D efinitions (p.2959 ) for their definitions . 40.10. Fast F our ier Transf orm (FFT ) Postpr ocessing When in terpreting time-sequenc e da ta fr om a tr ansien t solution, it is of ten useful t o lo ok a t the da ta’s spectral (fr equenc y) attribut es. For instanc e, you ma y want to det ermine the major v ortex-shedding frequenc y from the time-hist ory of the dr ag f orce on a b ody recorded dur ing an ANSY S Fluen t simula tion. Or, you ma y want to comput e the sp ectral distr ibution of sta tic pr essur e da ta recorded a t a par ticular location on a b ody sur face. Similar ly, you ma y need t o comput e the sp ectral distr ibution of turbulen t kinetic ener gy using da ta for fluc tuating v elocity comp onen ts.To in terpret some of these time dep enden t data, you need t o perform F ourier tr ansf orm analy sis. In essenc e, the F ourier tr ansf orm enables y ou t o take an y time dep enden t da ta and r esolv e it in to an equiv alen t summa tion of sine and c osine w aves. ANSY S Fluen t enables y ou t o analyz e your time dep enden t da ta using the F ast F ourier Transf orm (FFT ) algor ithm. Information on using the FFT algor ithm in ANSY S Fluen t is pr ovided in the f ollowing sec tions: 40.10.1. Limita tions of the FFT A lgor ithm 40.10.2. Windo wing 40.10.3. Fast F ourier Transf orm (FFT ) 40.10.4. Using the FFT U tility 40.10.1. Limita tions of the FFT A lgor ithm The f ollowing limita tions apply t o ANSY S Fluen t’s FFT mo dule: •The ANSY S Fluen t FFT mo dule c an only r ead inputs files in the ANSY S Fluen t report file , monit or, and x-y file f ormats. •The ANSY S Fluen t FFT mo dule assumes tha t the input da ta ha ve been sampled a t equal in tervals and ar e consecutiv e (in the or der of incr easing time). •The lo west fr equenc y tha t the FFT mo dule c an pick up is giv en b y , wher e is the t otal sampling time . If the sampled sequenc e contains fr equencies lo wer than this , these fr equencies will b e aliased in to higher frequencies . •The highest fr equenc y tha t the FFT mo dule c an pick up is , wher e is the sampling in terval (or time st ep). 40.10.2. Windo wing The discr ete FFT algor ithm is based on the assumption tha t the time-sequenc e da ta passed t o the FFT corresponds t o a single p eriod of a p eriodically r epeating signal. Since, in most situa tions , the first and the last da ta p oints will not c oincide , the r epeating signal implied in the assumption c an of ten ha ve a lar ge disc ontinuit y.The lar ge disc ontinuit y pr oduces high-fr equenc y comp onen ts in the r esulting Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2898Displa ying G raphicsFourier mo des, causing an aliasing er ror.You c an c ondition the input signal b efore the tr ansf orm b y “windo wing ” it, in or der t o avoid this pr oblem. Supp ose tha t we ha ve consecutiv e discr ete (time-sequenc e) da ta sampled with a c onstan t interval, : (40.28) Windo wing is done b y multiplying the or iginal input da ta ( ) by a windo w func tion, : (40.29) ANSY S Fluen t off ers f our diff erent windo w func tions: Hamming ’s windo w: (40.30) Hanning ’s windo w: (40.31) Barlett’s windo w: (40.32) Black man ’s windo w: (40.33) These windo w func tions pr eser ve a lar ge fr action ( ) of the or iginal da ta, affecting only of the da ta on b oth ends . 40.10.3. Fast F our ier Transf orm (FFT ) The F ourier tr ansf orm utilit y in ANSY S Fluen t enables y ou t o comput e the F ourier tr ansf orm of a signal, , a real-v alued func tion, from a finit e numb er of its sampled p oints. For a p eriodic set of sampled p oints, , the discr ete Fourier tr ansf orm [13] (p.4005 ) expresses the signal as a finit e trigonometr ic ser ies: (40.34) wher e the ser ies c oefficien ts are comput ed as 2899Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Fast F ourier Transf orm (FFT ) Postpr ocessing(40.35) Equa tion 40.34 (p.2899 ) and Equa tion 40.35 (p.2900 ) form a F ourier tr ansf orm pair tha t enables us t o de- termine one fr om the other . Note tha t when w e follow the c onvention of v arying from to in Equa tion 40.34 (p.2899 ) and Equa tion 40.35 (p.2900 ) inst ead of fr om to , the r ange of inde x corresponds to positiv e frequencies , and the r ange of inde x corresponds t o nega tive frequencies . still c orresponds t o zero frequenc y. For the ac tual c alcula tion of the tr ansf orms, ANSY S Fluen t adopts the so-c alled fast F ourier tr ansf orm (FFT ) algor ithm, which signific antly r educ es op eration c oun ts in c ompar ison t o the dir ect transf orm. Further mor e, unlik e most FFT algor ithms in which the numb er of da ta should b e a p ower of 2, the FFT utilit y in ANSY S Fluen t emplo ys a pr ime-fac tor algor ithm [134] (p.4012 ).The numb er of da ta p oints permissible in the pr ime-fac tor FFT algor ithm is an y pr oduc ts of mutually pr ime fac tors fr om the set , with a maximum v alue of .Thus, the pr ime-fac tor FFT pr eser ves the or iginal da ta b etter than the c onventional FFT . Just pr ior t o computing the tr ansf orm, ANSY S Fluen t det ermines the lar gest p ermissible numb er of data p oints based on the pr ime fac tors, disc arding the r est of the da ta. A list of these numb ers is provided in Table 40.2: Numb ers of D ata P oints Supp orted b y the P rime-F actor FFT A lgor ithm (p.2900 ). Table 40.2: Numb ers of D ata P oints S upp orted b y the P rime-F actor FFT A lgor ithm 34320 8580 3120 1386 572 220 70 2 36036 9240 3276 1430 616 234 72 4 40040 9360 3432 1456 624 240 78 6 48048 10010 3640 1540 630 252 80 8 51480 10296 3696 1560 660 260 84 10 55440 10920 3960 1584 720 264 88 12 60060 11088 4004 1638 728 280 90 14 65520 11440 4290 1680 770 286 104 16 72072 12012 4368 1716 780 308 110 18 80080 12870 4620 1820 792 312 112 20 90090 13104 4680 1848 840 330 120 22 102960 13860 5040 1872 858 336 126 24 120120 16016 5148 1980 880 360 130 26 144144 16380 5460 2002 910 364 132 28 180180 17160 5544 2184 924 390 140 30 240240 18018 5720 2288 936 396 144 36 360360 18480 6006 2310 990 420 154 39 720720 20020 6160 2340 1008 440 156 40 20592 6552 2520 1040 462 168 42 21840 6864 2574 1092 468 176 44 24024 6930 2640 1144 504 180 48 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2900Displa ying G raphics25740 7280 2730 1170 520 182 52 27720 7920 2772 1232 528 198 56 30030 8008 2860 1260 546 208 60 32760 8190 3080 1320 560 210 66 40.10.4. Using the FFT Utilit y The ANSY S Fluen t FFT utilit y is a vailable thr ough the Fourier Transf orm D ialog Box (p.3712 ) (Fig- ure 40.84: The F ourier Transf orm D ialog Box (p.2901 )). Results → Plots → FFT → Set U p... Figur e 40.84: The F our ier Transf orm D ialo g Box 40.10.4.1. Loading D ata for Sp ectral A nal ysis FFT analy sis r equir es an input signal da ta file c onsisting of time-sequenc e da ta.To load an input signal data file in to the Fourier Transf orm D ialog Box (p.3712 ), click Load Input F ile....This displa ys The S elec t File D ialog Box (p.569) wher e you c an br owse thr ough y our file dir ectories and lo cate your da ta file containing y our time-sequenc e da ta.To remo ve a file fr om the Files list, selec t it and then click Free File D ata. If you c omput ed ac oustic signals “on the fly ”, you ha ve the option of pr ocessing signal da ta fr om a file or pr ocessing r eceiver da ta st ored in memor y.To analyz e signal da ta fr om an e xisting input file , selec t Process F ile D ata under Process Options and pr oceed as descr ibed ab ove.To analyz e receiver data st ored in memor y, selec t Process Rec eiver under Process Options and selec t the appr opriate receiver in the Rec eiver list. 2901Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Fast F ourier Transf orm (FFT ) Postpr ocessingClick Plot FFT to displa y the sp ectral analy sis da ta and , if y ou ha ve enabled Acoustics A naly sis, to calcula te the o verall sound pr essur e level in dB based on the Referenc e Acoustic P ressur e and displa y it in the c onsole . Note You c an sp ecify the axis and axis v ariables if y our input r eport file c ontains multiple report definitions . 40.10.4.2. Customizing the Input and D efining the Sp ectrum Smo othing With the input signal da ta file loaded in to the Fourier Transf orm D ialog Box (p.3712 ), you ma y want to view a plot of the input signal and/or cust omiz e the da ta set in pr epar ation f or applying the FFT algor ithm. To do so , click the Plot/M odify Input S ignal butt on t o op en the Plot/M odify Input S ignal Dialog Box (p.3715 ) (Figur e 40.85: The P lot/M odify Input S ignal D ialog Box (p.2902 )). Figur e 40.85: The P lot/M odify Input S ignal D ialo g Box The Plot/M odify Input S ignal D ialog Box (p.3715 ) allo ws you t o analyz e a p ortion of the input signal, view input Signal S tatistics —Min,Max,Mean ,Varianc e, total Numb er of S amples , and Min F re- quenc y (tha t is, the finest p ossible fr equenc y resolution)—and set title and lab el inf ormation f or the input signal plot. Additionally , this dialo g box allo ws you t o enable and c ontrol the smo othing of the Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2902Displa ying G raphicsresulting sp ectrum b y sub dividing the input signal in to multiple segmen ts and a veraging the segmen t- based sp ectra. Note You c an sp ecify the axis and axis v ariables if y our input r eport file c ontains multiple report definitions . 40.10.4.2.1. Customizing the Input S ignal D ata S et By default , the en tire da ta set is analyz ed.To analyz e a p ortion of the input signal, enable the Clip to Range option and sp ecify the da ta range b y en tering Min and Max values under X A xis R ange . To ha ve the -axis quan tities r educ ed b y the Mean value of the r elevant signal pr operty, enable the Subtr act Mean Value option. The Set D efaults butt on will r eset the or iginal v alues f or the Min and Max fields under X A xis R ange and tur n off the Clip t o Range option. 40.10.4.2.2. Spectrum Smo othing Through S ignal S egmentation For long br oadband noise signals , the c omput ed F ourier sp ectrum ma y displa y spur ious fluc tuations of amplitudes b etween the neighb oring mo des. In or der t o obtain a smo oth sp ectrum, you c an split the signal in to multiple o verlapping segmen ts so tha t ANSY S Fluen t can apply the FFT algor ithm on each segmen t and then a verage the r esulting sp ectra.This pr ocedur e allo ws you t o signific antly suppr ess the spur ious fluc tuations a t the c ost of c oarsening the fr equenc y resolution of the sp ectrum. Note tha t the ar ithmetic a veraging of sp ectra is p erformed f or the squar es of F ourier amplitudes , thus c onser ving the signal ener gy. To use the smo othing pr ocedur e, enable the Subdivide in to Segmen ts option and define the seg- men t siz e and the o verlap of the subsequen t segmen ts in the Segmen t Control group b ox. Make a selec tion fr om the Control M etho d list t o sp ecify ho w you w ant to define the segmen t siz e: selec t Samples if y ou w ant to sp ecify the numb er of Samples p er S egmen t; selec t Frequenc y if y ou w ant to sp ecify the desir ed Frequenc y Resolution in H ertz units (the segmen t length in sec onds is then equal t o ).To help det ermine a suitable segmen t siz e, you c an use the Numb er of Samples and the Min F requenc y information in the Signal S tatistics group b ox. Note tha t the final segmen t length is selec ted b y ANSY S Fluen t to adher e to the lar gest supp orted numb er of da ta samples (see Table 40.2: Numb ers of D ata P oints Supp orted b y the P rime-F actor FFT A lgor ithm (p.2900 )). The ac tual signal length and the numb er of segmen ts will b e displa yed in the c onsole when y ou plot or wr ite the F ourier sp ectrum. The numb er of segmen ts dep ends on the Overlap of the sub- sequen t segmen ts, which is sp ecified r egar dless of which Control M etho d you selec t. If you selec t a Windo w func tion (see Windo wing (p.2898 ) for details), it is r ecommended tha t you use an Overlap value of a t least 0.125, in or der t o cover the signal p ortion aff ected b y the windo w func tion. Gener ally, an Overlap value of 0.5 is r ecommended .The e xact numb er of samples tha t are in the o verlapping region of the segmen t can b e det ermined fr om the segmen t hop siz e, which is displa yed in the console .The segmen t hop siz e is the distanc e (in t erms of samples) b etween the star ting samples of an y two adjac ent segmen ts (tha t is, the shif t from one segmen t to the ne xt), and has a minimum value of 1. The Set D efaults butt on will r eset the segmen t control values and disable the Subdivide in to Segmen ts option. 2903Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Fast F ourier Transf orm (FFT ) Postpr ocessing40.10.4.2.3. Viewing D ata Statistics To aid in the signal analy sis, whether f or the en tire input signal or f or a c ertain r ange of da ta, the Signal S tatistics group b ox in the Plot/M odify Input S ignal D ialog Box (p.3715 ) displa ys signal inf orm- ation such as the minimum, maximum, and a verage signal v alues , as w ell as the signal v arianc e, total numb er of samples , and finest p ossible fr equenc y resolution. 40.10.4.2.4. Customizing Titles and L abels You c an cr eate a new title or edit the or iginal title f or the input signal plot b y en tering a t ext str ing in Signal P lot Title. Likewise , you c an cr eate a new axis lab el or edit the or iginal axis lab el b y en tering a text str ing in to either Y A xis L abel or X A xis L abel. 40.10.4.2.5. Appl ying the C hanges in the Input S ignal D ata To apply an y changes y ou ha ve made in the Plot/M odify Input S ignal D ialog Box (p.3715 ) and view a plot of the input signal, click Apply/P lot. 40.10.4.3. Customizing the O utput In most pr actical applic ations with CFD da ta, you ma y want to find out ho w much p ower or ener gy is contained in a c ertain fr equenc y range , but do not w ant to distinguish p ositiv e and nega tive fre- quenc y. In r ecognition of this , all the outputs fr om the FFT mo dule in ANSY S Fluen t pertain t o one- sided sp ectra for the r ange of p ositiv e frequenc y. The Fourier Transf orm D ialog Box (p.3712 ) (Figur e 40.84: The F ourier Transf orm D ialog Box (p.2901 )) and Plot/M odify Input S ignal D ialog Box (p.3715 ) (Figur e 40.85: The P lot/M odify Input S ignal D ialog Box (p.2902 )) enable y ou t o set se veral diff erent func tions f or the and axes, apply diff erent FFT windo wing t echniques , and set v arious output options . 40.10.4.3.1. Specifying a F unc tion for the Y A xis You c an cho ose the -axis func tion using the Y A xis F unc tion drop-do wn list. Available options f or the -axis func tions ar e as f ollows. Note tha t the func tions r elated t o ac oustics (all of which ar e measur ed in dB) ar e only a vailable when the Acoustics A naly sis option is enabled . The definitions ar e pr ovided f or , and include c ontributions fr om b oth elemen ts of a c omple x conjuga te pair and - . Note tha t in ANSY S Fluen t, the v alue of is alw ays an e ven numb er. Power S pectral D ensit y is the distr ibution of signal p ower in the fr equenc y domain. Its value and units dep end on the X Axis Func tion choic e. For the detailed sp ectral represen tation with all r esolv ed har monics (tha t is, when X Axis F unc tion is either Frequenc y,Strouhal N umb er, or Four ier M ode), the Power S pectral D ensit y ( ) has units of the signal magnitude squar ed o ver the fr equenc y (for e xample , Pa2/Hz) and is defined for the fr equenc y as (40.36) wher e is the fr equenc y step in the discr ete sp ectrum, and the F ourier mo de p ower is comput ed as Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2904Displa ying G raphics(40.37) For the o ctave analy sis (tha t is, when the X A xis F unc tion is either Octave Band or 1/3-O ctave Band ), the Power S pectral D ensit y has units of the signal magnitude squar ed (f or e xample , Pa2), and is defined f or the fr equenc y band as (40.38) wher e includes all of the F ourier mo des b elonging t o the band . Magnitude is the amplitude . For the detailed sp ectral represen tation with all r esolv ed har monics (tha t is, when X Axis F unc tion is either Frequenc y,Strouhal N umb er, or Four ier M ode), the Magnitude ( ) is defined for the fr equenc y as (40.39) wher e is the mean signal v alue . For the o ctave analy sis (tha t is, when the X A xis F unc tion is either Octave Band or 1/3-O ctave Band ), the Magnitude is defined f or the fr equenc y band as (40.40) wher e is c alcula ted acc ording t o Equa tion 40.38 (p.2905 ). Sound P ressur e Level (dB) is the decib el le vel. For either gener al or ac oustic da ta, when the sampled da ta is pr essur e (for e xample , static pr essur e or sound pr essur e), the Sound P ressur e Level (dB) ( ) is c alcula ted in decib el units using (40.41) wher e is the Power S pectral D ensit y for either a par ticular F ourier mo de or a par ticular frequenc y band (see Equa tion 40.36 (p.2904 ) and Equa tion 40.38 (p.2905 )). is the r eference acoustic pr essur e, with a default v alue of 2 10-5 Pa; you c an r evise this v alue , as descr ibed in Enabling the FW-H A coustics M odel (p.1879 ). Sound A mplitude (dB) is similar t o the Sound P ressur e Level (dB) , and is a lo garithmic c onversion of the pr essur e signal Magnitude into decib el units .The Sound A mplitude (dB) ( ) is c alcula ted f or either a F ourier mo de or a fr equenc y band using (40.42) 2905Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Fast F ourier Transf orm (FFT ) Postpr ocessingA-W eigh ted, Sound P ressur e Level (dB A) is the c alcula ted sound pr essur e level w eigh ted b y the A-sc ale func tion t o mor e closely appr oxima te the fr equenc y response of the human ear . A-W eigh ting is applied f or loudness le vels b elow 55 phons (55 dB a t 1 kHz) and is the most c ommonly used w eigh ting func tion. See Figur e 40.86: A-, B-, and C- Weigh ting F unctions (p.2906 ) for a gr aphic al represen tation. This func tion is only a vailable when the X Axis F unc tion is either Octave Band or 1/3-O ctave Band . B-W eigh ted, Sound P ressur e Level (dB B) is the c alcula ted sound pr essur e level w eigh ted b y the B-sc ale func tion. B-W eigh ting is applied t o loudness le vels b etween 55 and 85 phons , though it is r arely used . See Figur e 40.86: A-, B-, and C- Weigh ting F unctions (p.2906 ) for a gr aphic al represen tation. This func tion is only a vailable when the X Axis F unc tion is either Octave Band or 1/3-O ctave Band . C-W eigh ted, Sound P ressur e Level (dB C) is the c alcula ted sound pr essur e level w eigh ted b y the C-sc ale func tion. C-W eigh ting is applied f or loudness le vels ab ove 85 phons and is c ommonly used f or high-in tensit y sound such as tr affic studies . See Figur e 40.86: A-, B-, and C-W eigh ting F unctions (p.2906 ) for a gr aphic al represen tation. This func tion is only a vailable when the X Axis F unc tion is either Octave Band or 1/3-O ctave Band . Figur e 40.86: A-, B-, and C-W eigh ting F unc tions Further gr aphic al cust omiza tions f or the -axis ar e available b y click ing the Axes... butt on. For mor e information, see Modifying A xis A ttribut es (p.2877 ). 40.10.4.3.2. Specifying a F unc tion for the X A xis There ar e thr ee options f or the -axis func tion y ou c an cho ose fr om in or der t o plot or wr ite the detailed sp ectrum with all r esolv ed F ourier mo des; these thr ee options ar e related t o the discr ete frequencies a t which the F ourier c oefficien ts ar e comput ed.There ar e also t wo additional options available when the Acoustics A naly sis option is enabled , which allo w the o ctave and 1/3 o ctave band analy sis.You c an apply sp ecific analytic func tions f or the -axis using the X A xis F unc tion drop-do wn list. Available options f or the -axis func tions ar e as f ollows.The definitions ar e pr ovided f or , because the c orresponding definitions f or the -axis func tions include c ontributions fr om b oth ele- men ts of a c omple x conjuga te pair and - . Note tha t in ANSY S Fluen t, the v alue of is alw ays an e ven numb er. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2906Displa ying G raphicsFrequenc y (Hz) is defined as: (40.43) wher e is the numb er of da ta p oints used in the FFT . Strouhal N umb er is the nondimensionaliz ed v ersion of the fr equenc y defined in Equa tion 40.43 (p.2907 ) : (40.44) wher e and are the r eference length and v elocity sc ales sp ecified in the Reference Values Task P age (p.3601 ). Four ier M ode is the inde x in Equa tion 40.34 (p.2899 ) and/or Equa tion 40.35 (p.2900 ), which r epresen ts the th term in the F ourier tr ansf orm of the signal. Octave Band (Hz) is a r ange of discr ete frequenc y bands f or diff erent octaves within the thr eshold of hear ing.The r ange of each o ctave band is double t o tha t of the pr evious band (see Table 40.3: Octave Band F requencies and Weigh tings (p.2907 )). 1/3-O ctave Band (Hz) is a r ange of discr ete frequenc y bands f or diff erent 1/3 o ctaves within the thr eshold of hear ing. Table 40.3: Octave Band F requencies and Weigh tings dB C dB B dB AUpper Freq. (Hz)Center Freq. (Hz)Lower Freq. (Hz) -8.5 -28.5 -56.7 22 16 11 -3.0 -17.1 -39.4 45 31.5 22 -0.8 -9.3 -26.2 90 63 45 -0.2 -4.2 -16.1 180 125 90 0.0 -1.3 -8.6 355 250 180 0.0 -0.3 -3.2 710 500 355 0.0 0.0 0.0 1400 1000 710 -0.2 -0.1 1.2 2800 2000 1400 -0.8 -0.7 1.0 5600 4000 2800 -3.0 -2.9 -1.1 11200 8000 5600 -8.5 -8.4 -6.6 22400 16000 11200 Further gr aphic al cust omiza tions f or the -axis ar e available b y click ing Axes.... For mor e inf ormation, see Modifying A xis A ttribut es (p.2877 ). 40.10.4.3.3. Specifying O utput O ptions You c an wr ite out the FFT da ta dir ectly t o a file b y cho osing the Write FFT t o File option under Options in the Fourier Transf orm D ialog Box (p.3712 ). Onc e the Write FFT t o File option is selec ted, 2907Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Fast F ourier Transf orm (FFT ) Postpr ocessingclick Write FFT to displa y a file selec tion dialo g box wher e you c an cho ose a file and/or a lo cation to hold the FFT da ta. If Acoustics A naly sis is selec ted, the o verall sound pr essur e level will b e calcu- lated in dB (based on the Referenc e Acoustic P ressur e) and displa yed in the c onsole a t this time . Further cust omiza tions f or ho w the FFT da ta is displa yed ar e available b y click ing Curves.... For mor e information, see Modifying C urve Attribut es (p.2879 ). 40.10.4.3.4. Specifying a Windo wing Technique You c an use the v arious windo wing t echniques descr ibed in Windo wing (p.2898 ) by selec ting an y of the Windo w options in the Plot/M odify Input S ignal D ialog Box (p.3715 ). By default ,None is selec ted so tha t no windo wing t echnique is applied . 40.10.4.3.5. Specifying L abels and Titles You c an assign a title f or y our FFT plot using the Plot Title text field .You c an also assign -axis and -axis lab els f or y our FFT plot using the Y A xis L abel and X A xis L abel text fields , respectively. By default ,ANSY S Fluen t assigns the Y A xis L abel and the X A xis L abel to the par ticular selec tion of Y Axis F unc tion and X A xis F unc tion . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2908Displa ying G raphicsChapt er 41: Rep orting A lphanumer ic D ata ANSY S Fluen t provides t ools f or c omputing and r eporting in tegral quan tities a t sur faces and b oundar ies. These t ools enable y ou t o find the mass flo w rate and hea t transf er rate thr ough b oundar ies, the f orces and momen ts on b oundar ies, and the ar ea, integral, flow rate, average, and mass a verage (among other quan tities) on a sur face or in a v olume . In addition, you c an pr int hist ograms of geometr ic and solution da ta, set r eference values f or the c alcula tion of non-dimensional c oefficien ts, and c omput e projec ted sur face ar eas.You c an also pr int or sa ve a summar y report of the mo dels , boundar y conditions , and solv er settings in the cur rent case.These f eatures ar e descr ibed in the f ollowing sec tions . 41.1. Reporting C onventions 41.2. Monit oring and R eporting S olution D ata 41.3. Creating Output P aramet ers 41.4. Fluxes Through B oundar ies 41.5. Forces on B oundar ies 41.6. Projec ted Sur face Area C alcula tions 41.7. Sur face Integration 41.8. Volume In tegration 41.9. Hist ogram R eports 41.10. Discrete Phase 41.11. S2S Inf ormation 41.12. Reference Values 41.13. Summar y Reports of C ase S ettings 41.14. System R esour ce Usage Reporting t ools f or the discr ete phase ar e descr ibed in Postpr ocessing f or the D iscrete Phase (p.2027 ). 41.1. Rep orting C onventions For 2D pr oblems , ANSY S Fluen t comput es all in tegral quan tities f or a unit depth equiv alen t to met er. This v alue c an b e adjust ed t o ma tch the sp ecific dimension of y our applic ation only b y manually r evising the Depth in the Reference Values Task P age (p.3601 ) (see Reference Values (p.2952 )). Imp ortant The default v alue of Depth will b e equiv alen t to met er, even if the units ar e changed f or depth in the Set U nits D ialog Box (p.3242 ) (for e xample , if the units f or depth are changed to cm in the Set U nits D ialog Box (p.3242 ), the v alue of Depth in the Reference Values Task Page (p.3601 ) will b e cm). Note tha t inputs f or DPM and fluid massflo w ar e alw ays assumed t o correspond t o a 1m deep v ersion of the mo del mo del and ar e sc aled acc ordingly . For e xample , if the r eference Depth is set t o 0.5 m, ef- fectively r educing the mo del b y half , massflo ws used in v olume in tegral calcula tions will b e half of the original massflo ws. For axisymmetr ic pr oblems , all in tegral quan tities ar e comput ed f or an angle of radians . 2909Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.41.2. Monit oring and Rep orting S olution D ata During the c ourse of a simula tion, you ma y want to monit or, print, write, and/or plot solution da ta; this is done using r eport definitions . A report definition is an objec t tha t sp ecifies a c ertain quan tity or set of v alues t o be comput ed a t the end of a solv er timest ep or it eration. You c an then cho ose t o ha ve multiple r eport definitions pr inted t o the c onsole , written t o a single file , or plott ed in the same windo w. You c an use r eport definitions t o monit or c onvergenc e, verify mesh indep endenc e, and r ecord time- histories.These r eport definitions c an monit or the v alue of field v ariables or func tions thr ough sp ecified operations , such as sur face, volume , force, momen t, and flux in tegrals. Onc e you cr eate report definitions , the y can b e added t o a r eport file . Report files c an include multiple report definitions of v aried t ypes. Multiple r eport definitions c an b e plott ed in the same gr aphics windo w by adding them t o a single r eport plot. One r eport definition c an b e included in multiple r eport plots and files . For additional inf ormation on r eport files and plots , see Report Files and R eport Plots (p.2929 ). 41.2.1. Creating Rep ort Definitions You c an cr eate report definitions fr om multiple lo cations in F luen t, allo wing y ou t o quick ly define r eport definitions , regar dless of wher e you ar e in y our w orkflow.The pr imar y metho d to cr eate a r eport definition is thr ough the r ibbon. For e xample: Solution → Rep orts → Definitions → New → Surface Rep ort → Area-W eigh ted A verage ... Opens the Surface Rep ort Definition dialo g box. Alternativ e metho ds f or acc essing this dialo g box ar e thr ough the tr ee, by right-click ing the Report Defin- ition branch, or thr ough the New drop-do wn list in the Figur e 41.1: Report Definitions D ialo g Box (p.2913 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2910Reporting A lphanumer ic DataMany of the setup st eps ar e the same or similar when setting up the v arious t ypes of r eport definitions . To setup the Sur face Report Definition dialo g box: 1.Enter a name f or the r eport definition under Name . 2.If you w ant the v alue r eported on individual sur faces rather than the net r esults fr om a gr oup of sur faces, enable the Per S urface option. 3.(optional) To ha ve Fluen t calcula te a r unning a verage f or the Surface Rep ort Definition you c an en ter a positiv e integer gr eater than 1 (the default) f or Average O ver. Specifying a numb er gr eater than 1 means that F luent will pr int, plot , and wr ite the r unning a verage value of the selec ted v ariable inst ead of the curr ent v alue of the same v ariable . The v alue r eported is a veraged o ver the last iterations/time st eps, wher e is y our sp ecified Average Over value .When the it eration/time st ep numb er is lo wer than , Fluent c alculat es the a verage of the available v ariable v alues . 2911Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Monit oring and R eporting S olution D ata4.If you w ant the r eport definition wr itten t o a file or plott ed, either selec t an e xisting r eport file or plot from the Rep ort Files or Rep ort Plots lists , or cr eate a new r eport file or plot b y enabling Rep ort File and/or Rep ort Plot in the Create group b ox. 5.If you w ant the r eport definition a vailable as an output par amet er, enable Create Output P aramet er. 6.Choose the sur face report definition in tegration metho d by selec ting Area,Integral,Standar d D eviation , Flow R ate,Mass F low R ate,Volume F low R ate,Area-W eigh ted A verage ,Mass-W eigh ted A verage , Sum,Uniformit y Inde x - M ass Weigh ted,Uniformit y Inde x - A rea Weigh ted,Facet A verage ,Facet Minimum ,Facet M aximum ,Vertex Average ,Vertex M inimum ,Vertex M aximum ,Custom Vector Based F lux,Custom Vector F lux, or Custom Vector Weigh ted A verage from the Rep ort Type drop- down list. These metho ds ar e descr ibed in Surface Integration (p.2947 ). 7.If you selec ted Custom Vector B ased F lux,Custom Vector F lux, or Custom Vector Weigh ted A verage from the Rep ort Type drop-do wn list , you must define the v ectors in the Custom Vectors group b ox. 8.Unless y ou ar e reporting a mass flo w rate or v olume flo w rate, specify the v ariable or func tion t o be integ- rated in the Field Variable drop-do wn list. First selec t the desir ed c ategor y in the upp er dr op-do wn list. You c an then selec t one of the r elated quan tities in the lo wer list. (See Field F unction D efinitions (p.2959 ) for an e xplana tion of the v ariables in the list.) I f you ar e running a multiphase simula tion y ou ma y need to selec t the phase of in terest (or mix ture) from the Phase drop-do wn list (dep ending on the field v ariable selec ted). Note •In gener al, you c an selec t an y arbitr ary field v ariable f or each r eport type. However, not all possible c ombina tions ar e ph ysically meaning ful. •For multiphase flo w, you should use only the Mass F low R ate integral to comput e the mass flow rate of the mix ture or f or an individual phase . Do not use the Flow R ate integral of the Volume F raction field v ariable as this will r esult in er roneous r esults . 9.Selec t the Surfaces wher e you w ant Fluen t to evalua te the sp ecified v ariable . 10.You ha ve the option t o highligh t a selec ted sur face and ha ve it displa yed in the gr aphics windo w by en- abling Highligh t Surfaces. 11.Click OK to create the r eport definition and close the dialo g box. Once you ha ve cr eated a r eport definition, it app ears in the Figur e 41.1: Report Definitions D ialo g Box (p.2913 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2912Reporting A lphanumer ic DataFigur e 41.1: Rep ort Definitions D ialo g Box You c an use this dialo g box to review and mo dify the pr operties of the e xisting r eport definitions . Note The r eport definitions tha t are aut oma tically cr eated f or tr ansien t simula tions (flo w-time , delta-time , iters-p er-timest ep) ar e not a vailable f or e xport or c opying . The f ollowing sec tions detail setup instr uctions tha t are sp ecific t o each t ype of r eport definition. 41.2.1.1. Sur face Report Definitions 41.2.1.2. Volume R eport Definitions 41.2.1.3. Force and M omen t Report Definitions 41.2.1.4. Flux R eport Definition 41.2.1.5. DPM R eport Definition 41.2.1.6. User D efined R eport Definition 41.2.1.7. Expr ession R eport Definition 2913Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Monit oring and R eporting S olution D ata41.2.1.1. Surface Report Definitions You c an use the Figur e 41.2: Sur face Report Definition D ialog Box (p.2915 ) to cr eate sur face report definitions .There ar e man y diff erent types of sur face-based r eport definitions tha t you c an cr eate, including: •Integral •Standar d Deviation •Flow Rate •Mass F low Rate (non-field based) •Volume F low Rate (non-field based) •Area-W eigh ted A verage •Mass-W eigh ted A verage •Sum •Uniformity Inde x — M ass Weigh ted •Uniformity Inde x — A rea Weigh ted •Facet A verage •Facet M inimum •Facet M aximum •Custom Vector B ased F lux (cust om-v ector based) •Custom Vector F lux (cust om-v ector based , non-field based) •Custom Vector Weigh ted A verage (cust om-v ector based) To plot or wr ite the sur face report definition da ta you must use a Rep ort File or Rep ort Plot. If a surface report definition is alr eady included in a r eport file/plot , then tha t report file/plot will b e highligh ted. If you de-selec t a r eport file/plot tha t had included the cur rent report definition and click OK, the r eport definition will b e remo ved fr om tha t report file/plot. For additional inf ormation on report files and plots , see Report Files and R eport Plots (p.2929 ). Solution → Rep orts → Definitions → New → Surface Rep ort Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2914Reporting A lphanumer ic DataFigur e 41.2: Surface Rep ort Definition D ialo g Box The pr ocedur e for cr eating sur face report definitions is c overed in Creating R eport Definitions (p.2910 ). 41.2.1.2. Volume R eport Definitions You c an use the Figur e 41.3: Volume R eport Definition D ialog Box (p.2916 ) to cr eate volume r eport definitions .There ar e man y diff erent types of v olume r eports tha t you c an cr eate, including: •Volume (non-field based) •Sum •Sum* (only axi-symmetr ic) •Max •Min 2915Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Monit oring and R eporting S olution D ata•Volume In tegral •Volume A verage •Mass In tegral •Mass A verage •Mass (non-field based) Solution → Rep orts → Definitions → New → Volume Rep ort Figur e 41.3: Volume Rep ort Definition D ialo g Box The c ommon st eps f or cr eating a v olume r eport definition ar e covered in Creating R eport Defini- tions (p.2910 ), and the v olume r eport definition-sp ecific st eps ar e as f ollows: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2916Reporting A lphanumer ic Data1.If you w ant the v alue r eported on individual w all z ones r ather than the net r esults fr om a gr oup of w all zones , enable the Per Z one option. 2.Choose the in tegration metho d for the v olume r eport definition b y selec ting Volume ,Sum,Sum*2P i (2D axisymmetr ic cases only), Max,Min,Volume In tegral,Volume-A verage ,Mass In tegral,Mass-A v- erage , or Mass in the Rep ort Type drop-do wn list. These metho ds ar e descr ibed in Volume In tegra- tion (p.2949 ). 3.Specify the v ariable or func tion t o be integrated in the Field Variable drop-do wn list. First selec t the desir ed c ategor y in the upp er dr op-do wn list. You c an then selec t one of the r elated quan tities in the lower list. (See Field F unction D efinitions (p.2959 ) for an e xplana tion of the v ariables in the list.) 4.Selec t the Cell Z ones wher e you w ant Fluen t to evalua te the sp ecified v ariable . 5.Click OK to create the r eport definition and close the dialo g box. 41.2.1.3. Force and Moment R eport Definitions Monit oring f orce coefficien ts can b e useful when y ou ar e calcula ting e xternal aer odynamics , for e x- ample , and ar e esp ecially in terested in the lif t coefficien t. By monit oring these v alues y ou ma y also be able t o stop the c alcula tion ear ly and r educ e the pr ocessing time , as sometimes the f orce and momen t coefficien ts converge b efore the r esiduals ha ve decr eased thr ee or ders of magnitude . (In such an instanc e, you should b e sur e to check the mass flo w rate and hea t transf er rate as w ell, to ensur e tha t the mass and ener gy are being suitably c onser ved.This is acc omplished using either the Figur e 41.5: Drag R eport Definition D ialog Box (p.2919 ), the Figur e 41.6: Lift Report Definition D ialog Box (p.2920 ), the Figur e 41.7: Momen t Report Definition D ialog Box (p.2921 ), or the Figur e 41.4: Force Report Definition D ialog Box (p.2918 )). To begin setting up f orce or momen t report definitions , first en ter appr opriate values in the Referenc e Values task page , as descr ibed in Reference Values (p.2952 ).The r elevant values include the f ollowing: •The force coefficien ts use the r eference area, densit y, and v elocity. •The momen t coefficien ts use the r eference area, densit y, velocity and length. For inf ormation ab out ho w these c oefficients ar e calculat ed, see Computing F orces, Moments , and the Center of P ressur e in the Fluent Theor y Guide . Tip You c an ha ve Fluen t report unsc aled f orce values b y selec ting Drag F orce or Lift Force in the Rep ort Output Type group b ox of the Drag Rep ort Definition or Lift Rep ort Definition dialo g boxes, respectively. Next, open the appr opriate dialo g box thr ough the Solution tab of the r ibbon. Solution → Rep orts → Definitions → New → Force Rep ort Selec t either Drag...,Lift...,Momen t..., or Force... to op en the Figur e 41.5: Drag R eport Definition Dialog Box (p.2919 ),Figur e 41.6: Lift Report Definition D ialog Box (p.2920 ),Figur e 41.7: Momen t Report Definition D ialog Box (p.2921 ), and Figur e 41.4: Force Report Definition D ialog Box (p.2918 ). Note tha t you c an only acc ess one of these r eport definition dialo g boxes a t a time , though multiple r eport definitions of the same t ype can b e used dur ing the simula tion. 2917Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Monit oring and R eporting S olution D ataFigur e 41.4: Force Rep ort Definition D ialo g Box Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2918Reporting A lphanumer ic DataFigur e 41.5: Drag Rep ort Definition D ialo g Box 2919Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Monit oring and R eporting S olution D ataFigur e 41.6: Lift Rep ort Definition D ialo g Box Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2920Reporting A lphanumer ic DataFigur e 41.7: Momen t Rep ort Definition D ialo g Box The c ommon st eps f or cr eating a f orce or momen t report definition ar e covered in Creating R eport Definitions (p.2910 ), and the f orce/momen t report definition-sp ecific st eps ar e as f ollows: 1.If you w ant to report the f orce or momen t coefficien t da ta fr om individual w all z ones r ather than the net r esults fr om a gr oup of w all z ones , enable the Per Z one option. 2.Depending on the c oefficien t tha t will b e monit ored, perform one of the f ollowing st eps: 2921Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Monit oring and R eporting S olution D ata•In the Drag Rep ort Definition ,Lift Rep ort Definition or Force Rep ort Definition dialo g box, enter the X,Y, and Z comp onen ts of the Force Vector along which the f orces will b e comput ed. By default , the Force Vector for the dr ag c oefficien t is a unit v ector in the direction, wher eas f or the lif t coefficien t it is a unit v ector in the direction. •In the Momen t Rep ort Definition dialo g box, enter the C artesian c oordina tes (X,Y, and Z) of the Momen t Center, about which momen ts will b e comput ed.The default Momen t Center is (0,0,0). You also need t o en ter the X,Y, and Z comp onen ts for the Momen t Axis, along which the momen t coefficien t will b e calcula ted. By default , the Momen t Axis is defined as a unit v ector in the direction. 3.Selec t the appr opriate wall z one(s) f or computa tion of the c oefficien t(s). 4.You ha ve the option t o highligh t a selec ted b oundar y zone and ha ve it displa yed in the gr aphics windo w by enabling Highligh t Zone . 5.Click OK to sa ve the r eport definition settings . 6.If you need t o revise the settings of a par ticular r eport definition af ter the y ha ve been sa ved, double- click the r eport definition in the tr ee. 41.2.1.4. Flux R eport Definition You c an use the Figur e 41.8: Flux R eport Definition D ialog Box (p.2923 ) to cr eate flux r eport definitions . There ar e man y diff erent types of flux-based r eport definitions tha t you c an cr eate, including: •Mass F low Rate •Total H eat Transf er R ate •Total S ensible H eat Transf er R ate •Radia tion H eat Transf er R ate •Film M ass F low Rate •Film H eat Transf er R ate •DPM M ass S ource •DPM En thalp y Source •DPM S ensible En thalp y Source Solution → Rep orts → Definitions → New → Flux Rep ort Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2922Reporting A lphanumer ic DataFigur e 41.8: Flux Rep ort Definition D ialo g Box 2923Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Monit oring and R eporting S olution D ataFigur e 41.9: DPM S our ce Rep ort Definition D ialo g Box The c ommon st eps f or cr eating a flux r eport definition ar e covered in Creating R eport Defini- tions (p.2910 ), and the flux r eport definition-sp ecific st eps ar e as f ollows: 1.Selec t or c onfir m the t ype of flux r eport. 2.Selec t the appr opriate boundar ies f or the flux c alcula tions . 3.Click OK to sa ve the r eport definition settings . 4.If you need t o revise the settings of a par ticular r eport definition af ter the y ha ve been sa ved, double- click the r eport definition in the tr ee. For additional inf ormation on the a vailable options f or DPM sour ce report definitions , see DPM S ource Report Definition (p.3807 ) in the r eference guide . 41.2.1.5. DPM R eport Definition You c an use the DPM R eport Definition dialo g box to cr eate DPM r eport definitions .The f ollowing types of DPM r eports ar e available: •Injec ted M ass (unst ead y par ticle tr ack ing onl y): Reports the t otal DPM mass injec ted in to the domain. •Mass in D omain (unst ead y par ticle tr ack ing onl y): Reports the t otal DPM mass pr esen t in the domain. •Mass in F luid (unst ead y par ticle tr ack ing onl y): Reports all DPM mass cur rently r esiding as fr ee-str eam particles in the domain. This option is a vailable only with the wall-film DPM b oundar y condition. •Mass in F ilm (unst ead y par ticle tr ack ing onl y): Reports all DPM mass cur rently r esiding in Lagr angian w all- film. This option is a vailable only with the wall-film DPM b oundar y condition. •Escaped M ass: Reports the DPM mass tha t has lef t the domain thr ough a c ertain b oundar y or b oundar ies. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2924Reporting A lphanumer ic Data•Evaporated M ass: Reports the t otal e vaporated DPM mass f or the selec ted injec tion(s). The quan tity ac- coun ts for fully e vaporated par ticles as w ell as all mass tha t has e vaporated fr om an y other par ticles . For unst eady tracking, this includes par ticles tha t are still pr esen t in the domain. •Penetr ation L ength (unst ead y par ticle tr ack ing onl y): Reports the t otal p enetr ation length in met ers. Solution → Rep orts → Definitions → New → DPM Rep ort Figur e 41.10: DPM Rep ort Definition D ialo g Box The c ommon st eps f or cr eating a DPM r eport definition ar e covered in Creating R eport Defini- tions (p.2910 ), and the DPM r eport definition-sp ecific st eps ar e as f ollows: 1.Selec t or c onfir m the t ype of DPM r eport. 2.For the Escaped M ass report, if you w ant to ha ve the esc aped mass c alcula ted p er injec tion, enable the text command report/dpm-zone-summaries-per-injection . The Injec tions selec tion list will then app ear in the DPM Rep ort Definition dialo g box. 2925Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Monit oring and R eporting S olution D ata3.From the Injec tions list, selec t the appr opriate injec tions f or the DPM r eport. Note For the Escaped M ass report, this st ep is r elevant only if y ou ha ve enabled the c alcu- lation of the esc aped mass p er injec tion. 4.For the Escaped M ass report, selec t the b oundar y(s) wher e the injec ted par ticles e xit the domain fr om the Boundar ies selec tion list. 5.For the Penetr ation L ength report, you c an sp ecify the Particles M ass F raction .You c an also enable User-S pecified Or igin and D irection to sp ecify those c oordina tes. 6.For unst eady par ticle tr acking, you c an selec t Show M ass F low/C hange R ate (default) f or the Injec ted Mass,Mass in D omain ,Mass in F luid ,Mass in F ilm,Escaped M ass, and Evaporated M ass reports if you w ant to create a r eport for the mass flo w rate rather than the t otal mass . 7.Click OK to sa ve the r eport definition settings . 8.If you need t o revise the settings of a par ticular r eport definition af ter the y ha ve been sa ved, double- click the r eport definition in the tr ee. Imp ortant For unst eady par ticle tr acking, if y ou w ant to selec t one or mor e injec tion(s) f or an y Escaped Mass report, you must enable the report/dpm-zone-summaries-per-injection text command b efore the first par ticles ar e injec ted; other wise , some of the r eported v alues may become inc onsist ent. For additional inf ormation on the a vailable options , see the DPM R eport Definition D ialog Box (p.3804 ) in the r eference guide . 41.2.1.6. User D efined R eport Definition User defined r eport definitions allo w you t o cr eate func tions tha t retur n values tha t can b e plott ed, printed, written, or used in other e xpressions . User defined r eport definitions c an also b e used in the Convergenc e Conditions (Convergenc e Conditions (p.2657 )). Creating a user defined r eport definition is a t wo step pr ocess: 1.Create a user defined r eport definition func tion. 2.Hook the user defined r eport definition func tion t o the user defined r eport definition. 41.2.1.6.1. User D efined R eport Definition F unc tion User defined r eport definition func tions ar e defined with the DEFINE_REPORT_DEFINITION_FN macr o, which tak es the func tion name as the ar gumen t.The func tion must r etur n a r eal v alue . Onc e written, it should b e compiled and loaded the same w ay as other user-defined func tions , see Inter- preting and C ompiling UDFs in the Fluent C ustomization Manual for mor e inf ormation. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2926Reporting A lphanumer ic DataThe func tion b ody should b e constr ucted similar ly to an y C func tion tha t retur ns a r eal v alue . Any valid C c ode c an b e included in the func tion b ody. DEFINE_REPORT_DEFINITION_FN can use all of the API s available f or other user-defined func tions , including: •Last e valua ted v alues of all r eport definitions . •Current values of all input par amet ers tha t ha ve been set t o be used inside user-defined func tions . See DEFINE_REPORT_DEFINITION_FN in the Fluent C ustomization Manual for inf ormation on writing user defined r eport definition func tions . 41.2.1.6.2. User D efined R eport Definition F unc tion H ooking With the user defined r eport definition func tion wr itten, you must ho ok this func tion t o the user defined r eport definition. The c ommon st eps f or cr eating a user defined r eport definition ar e covered in Creating R eport Definitions (p.2910 ), and the user defined r eport definition-sp ecific st eps ar e as f ollows: 1.Open the User D efined Rep ort definition dialo g box. Solution → Rep ort Definitions New → User D efined Figur e 41.11: User D efined Rep ort Definition D ialo g Box 2.Selec t your func tion fr om the Func tion drop-do wn list. 41.2.1.7. Expr ession R eport Definition You c an cr eate expressions fr om r eport definitions , allo wing y ou t o combine r eport definitions with mathema tical op erators t o cr eate a new r eport definition tha t can b e wr itten or plott ed. For e xample , you c an cr eate a pr essur e-dr op r eport for the diff erence in ar ea-w eigh ted pr essur es b etween an inlet 2927Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Monit oring and R eporting S olution D ataand an outlet. You c an also use an e xpression r eport definition t o mo dify a single r eport definition with e xpression func tions such as a ma thema tical func tion or r educ tion op eration. Solution → Rep orts → Definitions → New → Expression Figur e 41.12: Expression Rep ort Definition D ialo g Box The c ommon st eps f or cr eating an e xpression r eport definition ar e covered in Creating R eport Definitions (p.2910 ), and the e xpression r eport definition-sp ecific st eps ar e as f ollows: 1.Create the Rep ort Definition (s) tha t you will use t o create an Expression . 2.Use the dr op-do wns t o the r ight of the Definition box to selec t the r eport definition(s) and other v ariables and func tions , as r equir ed t o define y our desir ed e xpression r eport definition. You c an also dir ectly ent er the e xpression int o the Definition box—the dr op-do wns ar e available t o mak e the pr ocess easier . Note When y ou use cur ly br ackets "{}" t o sp ecify the name of a defined objec t, such as a r eport definition or a c ell r egist er, aut oma tic suggestions ar e disabled and y ou must pr ovide the displa y name of tha t objec t. 3.Click OK to create the e xpression r eport definition. Refer to Fluen t Expr essions Language (p.659) for additional inf ormation on cr eating e xpressions . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2928Reporting A lphanumer ic Data41.2.2. Rep ort Files and Rep ort Plots Rep ort Files and Rep ort Plots are collec tions of r eport definitions tha t are wr itten t o a single file (r eport file) or plott ed t o a gr aphics windo w (r eport plot) a t sp ecified in tervals. In st eady-sta te cases , report files ar e evalua ted a t the sp ecified it eration, wher eas in tr ansien t cases y ou ha ve the option t o sp ecify the e valua tion fr equenc y based on it erations or timest eps. Report definitions in the same Report Plot must ha ve the same units . Rep ort Files F ormat: "" "Iteration"|"Timestep" " etc.." ("Iteration"|"Timestep" "" ""...) ... Report definitions included in a r eport plot ar e plott ed in the sp ecified windo w at the sp ecified fr e- quenc y. It is p ossible t o plot the same r eport in multiple windo ws. Both r eport plots and r eport files provide the option t o pr int to the c onsole .You c an deac tivate the wr iting and plotting of individual report files and plots f or a par ticular c alcula tion; deac tivated r eport files and plots c an b e re-ac tivated at a la ter time . 41.2.2.1. Creating R eport Files In or der t o cr eate a r eport file y ou must ha ve first cr eated a r eport definition. Solution → Monit ors → Rep ort Files New... 2929Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Monit oring and R eporting S olution D ataFigur e 41.13: New Rep ort File D ialo g Box 1. Provide a name f or ho w you w ant this r eport file t o app ear in the F luen t tree. You ha ve the option t o deac tivate the wr iting of this r eport file b y de-selec ting the Active check b ox to the r ight of the Name . 2. Selec t one or mor e report definitions fr om Available Rep ort Definitions and click Add>> , to sp ecify the r eports you w ant wr itten t o the same file . 3. Provide an appr opriate name in the File N ame text box.The Full F ile N ame tha t app ears b elow the File N ame field is cr eated with a r un inde x and it eration/time st ep inde x, app ended t o the base name . 4. Specify the fr equenc y at which y ou w ant the r eport definitions wr itten t o the file . Note In a tr ansien t simula tion, If you sp ecify an Average O ver value in a r eport definition, you must set Get D ata E very to time-st ep or flow-time . If you set Get D ata E very to iteration , Fluen t will use the instan taneous v alue of the r eport definition. 5. Click OK to sa ve the new r eport file . You ha ve the option t o view—and edit —pr operties of r eport files tha t you cr eated pr eviously b y selec ting Edit... when y ou r ight-click Rep ort Files in the tr ee, which op ens the Figur e 41.14: Report File D efinitions D ialog Box (p.2931 ). Note that y ou c an also r ight-click an individual r eport definition t o mo dify it dir ectly. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2930Reporting A lphanumer ic DataFigur e 41.14: Rep ort File D efinitions D ialo g Box Selec ting a r eport file t o mo dify op ens the Figur e 41.15: Edit R eport File D ialog Box (p.2932 ). 2931Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Monit oring and R eporting S olution D ataFigur e 41.15: Edit Rep ort File D ialo g Box 41.2.2.2. Creating R eport Plots In or der t o cr eate a r eport plot y ou must ha ve first cr eated a r eport definition. Solution → Monit ors → Rep ort Plots New... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2932Reporting A lphanumer ic DataFigur e 41.16: New Rep ort Plot D ialo g Box 1. Provide a name f or ho w you w ant this r eport plot t o app ear in the F luen t tree. You ha ve the option t o deac tivate the plotting of this r eport plot b y de-selec ting the Active check box to the r ight of the Name . 2. Selec t one or mor e report definitions fr om Available Rep ort Definitions and click Add>> , to sp ecify the r eports you w ant plott ed in the same windo w. 3. Provide an appr opriate names in the Plot Title and Y-A xis L abel group b oxes. 4. Specify the fr equenc y at which y ou w ant the r eport definitions plott ed t o the sp ecified windo w. Note In a tr ansien t simula tion, If you sp ecify an Average O ver value in a r eport definition, you must set Get D ata E very to time-st ep or flow-time . If you set Get D ata E very to iteration , Fluen t will use the instan taneous v alue of the r eport definition. 5. Click OK to sa ve the new r eport plot. You ha ve the option t o edit r eport plots tha t you cr eated pr eviously b y selec ting Edit... when y ou right-click Rep ort Plots in the tr ee, which op ens the Figur e 41.17: Report Plot D efinitions D ialog Box (p.2934 ). 2933Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Monit oring and R eporting S olution D ataOnc e you b egin it erating , Fluen t displa ys report plots in the gr aphics windo w. If you close the graphics windo w containing a plot , you c an r edispla y it b y right-click ing the r eport plot in the Outline View tr ee and selec ting Plot. Figur e 41.17: Rep ort Plot D efinitions D ialo g Box Selec ting a r eport plot t o mo dify op ens the Figur e 41.18: Edit R eport Plot D ialog Box (p.2935 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2934Reporting A lphanumer ic DataFigur e 41.18: Edit Rep ort Plot D ialo g Box 41.3. Creating Output P aramet ers You c an cr eate output par amet ers, which allo w you t o compar e reporting v alues f or diff erent cases , or include r eporting v alues in the func tion minimiz ed b y the mesh mor pher/optimiz er.These ar e single values gener ated b y a v ariety of r eports: •Fluxes (Fluxes Through B oundar ies (p.2937 )) •Forces (Forces on B oundar ies (p.2942 )) •Surface integrals ( Gener ating a Sur face Integral Report (p.2947 )) •Volume in tegrals ( Gener ating a Volume In tegral Report (p.2949 )) •Surface report definitions ( Surface Report Definitions (p.2914 )) •Volume r eport definitions ( Volume R eport Definitions (p.2915 )) •Drag r eport definitions ( Force and M omen t Report Definitions (p.2917 )) •Lift report definitions( Force and M omen t Report Definitions (p.2917 )) •Momen t report definitions( Force and M omen t Report Definitions (p.2917 )) •Force report definitions( Force and M omen t Report Definitions (p.2917 )) 2935Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Creating Output P aramet ers•User D efined r eport definitions( User D efined R eport Definition (p.2926 )) •Expr ession r eport definitions ( Expr ession R eport Definition (p.2927 )) Click Paramet ers... in the User D efined ribbon tab ( Field F unc tions group b ox) to op en the Paramet ers Dialog Box (p.3738 ), wher e a list of an y pr eviously cr eated input par amet ers is a vailable . User D efined → Field F unc tions → Paramet ers... The list of Input P aramet ers is p opula ted af ter p erforming the st eps outlined in Defining and Viewing Paramet ers (p.842).The output par amet ers tha t you cr eate will b e list ed under Output P aramet ers. You c an define the output par amet ers using the r eporting dialo g boxes, as descr ibed in Creating R eport Definitions (p.2910 ).The r eporting dialo g boxes ar e acc essible Definitions drop-do wn list in the Solution ribbon tab ( Rep orts group b ox). Clicking the Create drop-do wn list under Output P aramet ers in the Paramet ers dialo g box allo ws you t o selec t From Rep ort Definitions ..., which op ens the Figur e 41.1: Re- port Definitions D ialog Box (p.2913 ). From ther e you c an cr eate an y type of r eport definition. Onc e you ha ve sa ved y our output par amet ers, you c an mo dify their definitions b y selec ting the par a- met er in the Output P aramet ers list and click ing Edit....This will op en the r eport dialo g box wher e you c an mak e your changes . In addition, you c an selec t an y of the f ollowing c ommands under the More drop-do wn list: Delet e remo ves the selec ted output par amet er fr om the list of Output P aramet ers. Rename allows you t o rename the selec ted output par amet er. Print to Console reports values t o the c onsole windo w. If you selec t multiple output par amet ers, then the output includes values fr om multiple output par amet ers. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2936Reporting A lphanumer ic DataPrint All to Console outputs the v alues fr om all output par amet ers t o the c onsole windo w. Write... allows you t o store the output t o a file . A dialo g box is displa yed allo wing y ou t o pr ovide a file name . Write All... prompts y ou f or a file name and then wr ites the v alues f or all of the output par amet ers t o a file . 41.4. Fluxes Through B oundar ies This sec tion c ontains inf ormation ab out gener ating a flux r eport. For mor e back ground inf ormation, see Fluxes Through B oundar ies in the Theor y Guide . For additional inf ormation, see the f ollowing sec tions: 41.4.1. Gener ating a F lux R eport 41.4.2. Flux R eporting f or R eacting F lows 41.4.3. Flux R eporting with P articles 41.4.4. Flux R eporting with M ultiphase 41.4.5. Flux R eporting with O ther Volumetr ic Sources 41.4.1. Gener ating a F lux Rep ort To obtain a r eport of mass flo w rate, total hea t transf er rate, total sensible hea t transf er rate, or r adia tion heat transf er rate on selec ted b oundar y zones , use the Flux R eports D ialog Box (p.3723 ) (Figur e 41.19: The Flux R eports D ialog Box (p.2937 )). Results → Rep orts → Fluxes Edit... Figur e 41.19: The F lux Rep orts D ialo g Box The st eps f or gener ating the r eport are as f ollows: 2937Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Fluxes Through B oundar ies1.Specify which flux c omputa tion y ou ar e interested in b y selec ting one of the f ollowing under Options : •Mass F low R ate •Total H eat Transf er R ate •Total S ensible H eat Transf er R ate •Radia tion H eat Transf er R ate The net flux fr om v olumetr ic radia tion sour ces is r eported in the Net R adia tion S our ce field . •Film M ass F low R ate (available as an option only when the E uler ian Wall F ilm mo del is enabled—see Modeling E uler ian Wall F ilms (p.2337 )) •Film H eat Transf er R ate (available as an option only when the E uler ian Wall F ilm mo del is enabled—see Modeling E uler ian Wall F ilms (p.2337 )) 2.In the Boundar ies list, cho ose the b oundar y zone(s) on which y ou w ant to report flux es. You c an use Filter Text entry box to filt er the Boundar ies list t o sho w only the b oundar y zones that ma tch the pa ttern you en ter. For additional inf ormation on using the Filter Text entry box, see Filter Text En try Boxes (p.565). 3.To create an output par amet er for the r eported v alue , click Save Output P aramet er....The Save Output Paramet er D ialog Box (p.3743 ) (Figur e 41.20: The S ave Output P aramet er D ialog Box (p.2938 )) will op en wher e you will sp ecify the name of the newly cr eated output par amet er, or o verwrite an e xisting output paramet er of the same t ype. ANSY S Fluen t aut oma tically cr eates gener ic default names f or new input and output par amet ers (f or e xample , par amet er-1, par amet er-2, and so on). Figur e 41.20: The S ave Output P aramet er D ialo g Box Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2938Reporting A lphanumer ic DataAfter the output par amet er is cr eated, it is list ed in the Paramet ers D ialog Box (p.3738 ), acc essed via the Paramet ers... butt on in the Reports Task P age (p.3721 ).You c an cr eate an y numb er of output paramet ers of this r eport type. Note If you cr eate an output par amet er fr om a flux r eport and sa ve the c ase and da ta (wr ite), an equiv alen t report definition will b e created when y ou r ead in the c ase file . 4.Click the Comput e butt on t o displa y the r esults of the selec ted flux c omputa tion f or each selec ted boundar y zone . The Net Results field sho ws the summa tion of the individual z one flux r esults . If you sp ecified the mass sour ce terms in the Fluid dialo g box, the in tegral mass flo w rate value fr om the user-sp ecified sour ces is r eported in the User S our ce field and is added t o the Net Results . Similar ly, if y ou sp e- cified the ener gy sour ce terms in the Fluid dialo g box, the in tegral total hea t transf er rate value from the user-sp ecified sour ces is r eported in the User S our ce field and is added t o the net hea t balanc e results r eported in Net Results . Imp ortant •Additional st eps must b e tak en pr ior t o gener ating a flux r eport for an in terior b oundar y zone that has the same fluid defined on either side . In such a c ase, the ar ea v ectors of the c ell fac es asso ciated with the z one ma y ha ve been aut oma tically defined in an inc onsist ent manner when the mesh file w as read in to the solv er. Since the flux f or each individual c ell fac e is c alcula ted with r espect to its ar ea v ector, such an inc onsist ency leads t o inaccur ate results when the fac e fluxes ar e summed t o calcula te the t otal flux of the b oundar y zone . •To ensur e accur ate flux r esults f or such an in terior z one , you must or ient the ar ea v ectors b y changing the definition of the z one Type to wall.You should then change the Type back t o interior and pr oceed t o gener ate the flux r eport. •Mass F low R ate is calcula ted thr ough the simula tion domain or the sp ecified z ones . However, if you sp ecify only the in terior z one(s), the net mass flo w rate ma y sho w as 0, because these in- ternal b oundar ies ar e sk ipped when ANSY S Fluen t comput es the net influx and outflux. Note tha t the flux es ar e reported e xactly as c omput ed b y the solv er.Therefore, the y are inher ently mor e accur ate than those c omput ed with the Flow R ate option in the Surface In tegrals D ialog Box (p.3726 ) (descr ibed in Surface In tegration (p.2947 )). 41.4.2. Flux Rep orting f or Reac ting F lows To report hea t transf er for reacting flo ws, one of mo dels in the Species M odel D ialog Box (p.3294 ) must be enabled f or the Total S ensible H eat Transf er R ate option t o app ear in the Flux R eports D ialog Box (p.3723 ). For reacting flo ws, ANSY S Fluen t produces two kinds of r eports tha t use a diff erent treatmen t at the flo w b oundar ies: •Total H eat Transf er R ate reports the t otal en thalp y flux, which c onsists of the ther mal en thalp y, plus the species f ormation en thalp y when Volumetr ic Reac tions are enabled .The hea t rate based on this definition is a c onser ved quan tity in r eacting flo ws. See Heat Transf er Theor y in the Theor y Guide for details . 2939Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Fluxes Through B oundar ies•Total S ensible H eat Transf er R ate reports the t otal ener gy flux as defined in Equa tion 5.2 in the Theor y Guide . Note tha t in r eacting flo ws, this is not a c onser ved quan tity and the addition or r emo val of hea t due t o the chemic al reactions ( Equa tion 5.10 in the Theor y Guide ) is r eported separ ately in the Heat of Reac tion S our ce field , as sho wn in Figur e 41.21: The F lux R eports D ialog Box (p.2940 ). If you ha ve mor e than one r eaction defined in y our c ase, the Heat of Reac tion S our ce reported is the sum of the hea t for all r e- actions . For e xother mic r eactions the Heat of Reac tion S our ce is reported as a p ositiv e quan tity, while f or endother mic r eactions it will b e a nega tive quan tity. Figur e 41.21: The F lux Rep orts D ialo g Box Imp ortant Note tha t both the Total H eat Transf er R ate and Total S ensible H eat Transf er R ate options report a Net Result , which ma y be used as an indic ation of the ener gy balanc e for the c ase. In gener al, and if hea t sour ces other than the hea t of r eaction and DPM ar e not included in your pr oblem, the Net Result reported in b oth the Total H eat Transf er R ate and Total Sensible H eat Transf er R ate options should b e a small numb er for a c onverged c alcula tion. However, if a r eacting c ase is not w ell c onverged f or b oth ener gy and sp ecies tr ansp ort equa tions , the Net Result reported in the Total H eat Transf er R ate and Total S ensible Heat Transf er R ate options ma y diff er. In tha t case, you ma y consider it erating fur ther t o achie ve a fully c onverged solution. In addition, refer to the sec tions tha t follow for sp ecial consider ations when including par ticles , multiphase mo dels , or other v olumetr ic ener gy sour ces. Imp ortant Note tha t for the non-pr emix ed and par tially pr emix ed mo dels the Heat of Reac tion S our ce is calcula ted as the diff erence of the net Total H eat Transf er R ate and the net Total Sensible H eat Transf er R ate.The Heat of Reac tion field func tion is not a vailable f or the non-pr emix ed and par tially-pr emix ed mo dels . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2940Reporting A lphanumer ic Data41.4.3. Flux Rep orting with P articles If you ar e using the discr ete phase mo del (DPM), the c ontributions fr om the par ticle injec tions ar e re- ported separ ately and ar e included in the net mass and hea t balanc e results . Consequen tly, the Mass Flow R ate report includes the DPM M ass S our ce, the Total H eat Transf er R ate report includes the DPM E nthalp y Sour ce, and the Total S ensible H eat Transf er R ate includes the DPM S ensible E n- thalp y Sour ce (Figur e 41.22: The F lux R eports D ialog Box with DPM (p.2941 )). Figur e 41.22: The F lux Rep orts D ialo g Box with DPM For P1 or discr ete or dina tes (DO) r adia tion simula tions , if Particle R adia tion In teraction is selec ted in the Physical M odels tab of the Discr ete Phase M odel dialo g box, the Radia tion H eat Transf er Rate reports the diff erence between the r adia tion emitt ed and the r adia tion absorb ed on the sur face of the par ticles in the DPM R adia tion S our ce field . Imp ortant In the c ase of r eacting flo ws with the DPM mo del, the Heat of Reac tion S our ce entry reports the hea t of all homo geneous r eactions in the c ontinuous phase , while the hea t released or consumed due t o par ticle r eactions (e .g, char c ombustion) is r eported in the DPM S ensible Enthalp y Sour ce field . 41.4.4. Flux Rep orting with M ultiphase If you ar e using an y of the multiphase mo dels , the mass or hea t rates c an b e reported separ ately f or each phase and f or the mix ture phase . If you sp ecified the mass sour ce terms in the c ell z one c onditions dialo g box for a sp ecific phase , then the in tegral mass flo w rate value fr om the user-sp ecified sour ces is reported f or the r elevant phase in the User S our ce field and is added t o the net mass balanc e results reported in Net Results . Similar ly, if y ou sp ecified the ener gy sour ce terms in the c ell z one c onditions dialo g box for a sp ecific phase , the in tegral total hea t transf er rate value fr om the user-sp ecified sour ces is reported f or the r elevant phase in the User S our ce field and is added t o the net hea t balanc e results 2941Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Fluxes Through B oundar iesreported in Net Results . For the E uler ian multiphase mo del, in addition t o reporting f or the phases , the user sour ce flux is also r eported f or the mix ture. Note tha t if y our multiphase mo del includes mass or hea t transf er pr ocesses b etween phases , the mass and hea t transf erred acr oss the phases will b e reported as an imbalanc e in the r eport of each phase . In or der t o check the o verall balanc es for the multiphase c ases y ou should selec t the mix ture phase for y our r eport. In tha t case, the r eport will include the sum of the flux es and sour ces for all phases included in y our mo del. Finally , if y ou ar e solving a multiphase pr oblem tha t includes chemic al reactions , you should b e aware of the f ollowing c onventions when y ou ar e requesting a Total S ensible H eat Transf er R ate report: •If you selec t one of the phases with gas phase chemic al reactions , the Heat of Reac tion S our ce will only include c ontributions fr om r eactions in the par ticular phase . •When y ou r eport the Total S ensible H eat Transf er R ate for the mix ture phase , the Heat of Reac tion Sour ce entry will r eport the sum of the hea t of r eaction of all gas phase r eactions in all phases plus the heat of an y het erogeneous r eactions tha t tak e plac e. 41.4.5. Flux Rep orting with O ther Volumetr ic Sour ces The r eported mass and hea t balanc es addr ess the flo w tha t en ters or lea ves the domain thr ough boundar ies and the c ontributions fr om DPM sour ces and user-defined sour ces; the y do not include the c ontributions fr om other v olumetr ic sour ces, such as the hea t exchanged in the H eat Exchanger Model. For this r eason, a mass or hea t imbalanc e ma y be reported. In tha t case, and in a c onverged calcula tion, the r eported imbalanc e will b e equal t o tha t volumetr ic sour ce. For a Radia tion H eat Transf er R ate flux r eport, the Net R adia tion S our ce field pr ovides the net flux from v olumetr ic radia tion sour ces and is c omput ed as the diff erence between the emitt ed and absorb ed volumetr ic radia tion sour ces. 41.5. Forces on B oundar ies For w all z ones tha t you selec t, you c an c omput e and r eport the f orces along a sp ecified v ector, the momen ts ab out a sp ecified c enter and along a sp ecified axis , and the c oordina tes of the c enter of pressur e.This f eature is useful f or reporting , for instanc e, aer odynamic quan tities such as lif t, drag, and momen t coefficien ts, as w ell as the c enter of pr essur e for an air foil. For additional inf ormation ab out f orces, momen ts, and the c enter of pr essur e, see Computing F orces, Momen ts, and the C enter of P ressur e in the Theor y Guide . For additional inf ormation, see the f ollowing sec tion: 41.5.1. Gener ating a F orce, Momen t, or C enter of P ressur e Report 41.5.1. Gener ating a F orce, Momen t, or C enter of P ressur e Rep ort To obtain a r eport (for selec ted w all z ones) of f orces along a sp ecified v ector, momen ts ab out a sp ecified center and along a sp ecified axis , or the c enter of pr essur e, use the Force Reports D ialog Box (p.3724 ) (Figur e 41.23: The F orce Reports D ialog Box (p.2943 )). Results → Rep orts → Forces Edit... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2942Reporting A lphanumer ic DataFigur e 41.23: The F orce Rep orts D ialo g Box The st eps f or gener ating the r eport are as f ollows: 1.Specify the t ype of r eport in which y ou ar e interested b y selec ting Forces,Momen ts, or Center of P ressur e from the Options list. 2.Define the settings asso ciated with r eport you ar e gener ating: a.For a f orce report, enter the X,Y, and Z comp onen ts of the Force Vector along which the f orces will be comput ed. Imp ortant If (the -comp onen t of the f orce) is z ero, then either the Y or Z coordina te can be fix ed. If is z ero, then either the X or Z coordina te can b e fix ed. If is z ero, then either the X or Y coordina te can b e fix ed. b.For a momen t report, enter the X,Y, and Z coordina tes of the Momen t Center about which the mo- men ts will b e comput ed, as w ell as the X,Y, and Z comp onen ts of the Momen t Axis along which the momen ts will b e comput ed. c.For a c enter of pr essur e report, define the line (f or 2D geometr ies) or plane (f or 3D geometr ies) on which y ou w ant to calcula te the c enter of pr essur e.The line or plane must ha ve one of its c oordina te values fix ed (f or e xample , a line defined as ). Selec t the axis ( X,Y, or Z) in the Coordina te group box, and then en ter the fix ed Value . See the e xample a t the end of this sec tion f or fur ther details . 3.In the Wall Z ones list, selec t the w all z one(s) f or which y ou w ant a r eport of the f orces, momen ts, or pressur e center. 4.To create an output par amet er for the r eported v alue , click Save Output P aramet er....The Save Output Paramet er D ialog Box (p.3743 ) (Figur e 41.20: The S ave Output P aramet er D ialog Box (p.2938 )) will op en wher e you will sp ecify the name of the newly cr eated output par amet er, or o verwrite an e xisting output 2943Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Forces on B oundar iesparamet er of the same t ype. ANSY S Fluen t aut oma tically cr eates gener ic default names f or new input and output par amet ers (f or e xample , par amet er-1, par amet er-2, and so on). After the output par amet er is cr eated, it is list ed in the Paramet ers D ialog Box (p.3738 ).You c an create an y numb er of output par amet ers of this r eport type. Note If you cr eate an output par amet er fr om a f orce, momen t, or c enter of pr essur e report and sa ve the c ase and da ta (wr ite), an equiv alen t report definition will b e created when you r ead in the c ase file . 5.Click the Print butt on if y ou w ant the r esults displa yed in the c onsole windo w, or click Write... to sa ve it to a file . If you selec ted Forces under Options , the pr essur e force, visc ous f orce (if appr opriate), total f orces, pressur e coefficien t, visc ous c oefficien t, and t otal c oefficien ts for each selec ted w all z one will b e displa yed or sa ved. If you selec ted Momen ts, the pr essur e momen ts, visc ous momen ts (if appr opriate), total momen ts, pressur e coefficien t, visc ous c oefficien t and t otal c oefficien ts for the w all z ones ab out the sp ecified center will b e displa yed or sa ved. Additionally , the momen ts and c oefficien ts in the dir ection of the sp ecified axis will b e displa yed or sa ved.The r eport will include the v alues f or the individual wall z ones , as w ell as the net v alues f or all of the w all z ones c ombined . See Computing F orces, Momen ts, and the C enter of P ressur e in the Theor y Guide for details ab out c omputing f orces and momen ts. If you selec ted Center of P ressur e, then ANSY S Fluen t displa ys or sa ves the c oordina tes ab out which the momen t is z ero. Imp ortant You c annot sa ve your output par amet er if Center of P ressur e is selec ted; Center of Pressur e is not a vailable as an output par amet er sinc e it is a set of c oordina tes. Imp ortant Note tha t the r eported f orce and momen t coefficien ts ar e a func tion of the v alues en tered in the Referenc e Values task page (as descr ibed in Computing F orces, Momen ts, and the Center of P ressur e in the Theor y Guide ).Therefore, appr opriate values must b e en tered in the Referenc e Values task page t o get meaning ful r esults . 41.5.1.1. Example To demonstr ate ho w you w ould gener ate and in terpret the c enter of pr essur e report, consider an airfoil of chor d length 1 m (sho wn in Figur e 41.24: An Airfoil with its C omput ed C enter of P res- sure (p.2945 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2944Reporting A lphanumer ic DataFigur e 41.24: An A irfoil with its C omput ed C enter of P ressur e Open the Force Rep orts dialo g box and p erform the st eps tha t follow. Results → Rep orts → Forces Edit... Figur e 41.25: The F orce Rep orts D ialo g Box for a C enter of P ressur e Rep ort 1.Selec t Center of P ressur e from the Options list. 2945Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Forces on B oundar ies2.Define the line on which the c enter of pr essur e will b e calcula ted. In this c ase, the Y coordina te for the line has a fix ed Value of 10. 3.Selec t the Wall Z ones tha t are relevant for the c omputa tion. 4.Click Print to ha ve the c oordina tes of the c enter of pr essur e displa yed in the c onsole windo w. The r eport gener ated will b e in the f ollowing f orm: Pressure Center Coordinates (in m): X = 0.41267981 Y = 10 41.6. Projec ted S urface Area C alcula tions You c an use the Projec ted Sur face Areas D ialog Box (p.3725 ) (Figur e 41.26: The P rojec ted Sur face Areas Dialog Box (p.2946 )) to comput e an estima ted ar ea of the pr ojec tion of selec ted sur faces along the , , or axis (tha t is, onto the , , or plane). Results → Rep orts → Projec ted A reas Edit... Figur e 41.26: The P rojec ted S urface Areas D ialo g Box The st eps f or c alcula ting the pr ojec ted ar ea ar e as f ollows: 1.Selec t the Projec tion D irection (X,Y, or Z). 2.Choose the sur face(s) f or which the pr ojec ted ar ea is t o be calcula ted in the Surfaces list. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2946Reporting A lphanumer ic Data3.Set the Min F eature Size to the length of the smallest f eature in the geometr y tha t you w ant to resolv e in the ar ea c alcula tion. (You c an just use the default v alue t o star t with, if you ar e not sur e of the siz e of the smallest geometr ical feature.) 4.Click Comput e.The ar ea will b e displa yed in the Area box and in the c onsole windo w. 5.To impr ove the accur acy of the ar ea c alcula tion, reduc e the Min F eature Size by half and r ecomput e the area. Repeat this st ep un til the c omput ed Area stops changing (or y ou r each memor y capacit y). This f eature is a vailable only f or 3D domains . 41.7. Surface In tegration This sec tion descr ibes ho w to comput e sur face in tegrals. For ma thema tical definitions of the v arious integral types, refer to Computing Sur face In tegrals in the Theor y Guide . For additional inf ormation, see the f ollowing sec tion: 41.7.1. Gener ating a Sur face Integral Report 41.7.1. Gener ating a S urface In tegral Rep ort To obtain a r eport for selec ted sur faces of the ar ea, cust om v ector-based flux, cust om v ector flux, cust om v ector-w eigh ted a verage, mass flo w rate, or v olume flo w rate, or the in tegral, flow rate, standar d de viation, sum, facet maximum, facet minimum, unif ormity inde x (w eigh ted b y mass or ar ea), vertex maximum, vertex minimum, or mass-, area-, facet-, or v ertex-averaged quan tity of a sp ecified field v ariable , use the Surface In tegrals D ialog Box (p.3726 ) (Figur e 41.27: The Sur face In tegrals D ialog Box (p.2948 )). Results → Rep orts → Surface In tegrals Edit... 2947Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Surface IntegrationFigur e 41.27: The S urface In tegrals D ialo g Box The st eps f or gener ating the r eport are as f ollows: 1.Specify which t ype of r eport you ar e interested in b y selec ting Area,Area-W eigh ted A verage ,Custom Vector B ased F lux,Custom Vector F lux,Custom Vector Weigh ted A verage ,Facet A verage ,Facet Minimum ,Facet M aximum ,Flow R ate,Integral,Mass F low R ate,Mass-W eigh ted A verage ,Standar d Deviation ,Sum,Uniformit y Inde x - M ass Weigh ted,Uniformit y Inde x - A rea Weigh ted,Vertex Average , Vertex M inimum ,Vertex M aximum , or Volume F low R ate in the Rep ort Type drop-do wn list. 2.If you selec ted Custom Vector B ased F lux,Custom Vector F lux, or Custom Vector Weigh ted A verage from the Rep ort Type drop-do wn list , you must define v ectors in the Custom Vectors group b ox. 3.If you ar e performing a multiphase simula tion, you ma y need t o selec t the phase of in terest fr om the Phase drop-do wn list dep ending on the selec ted Rep ort Type. 4.If you ar e gener ating a r eport of ar ea, mass flo w rate, or v olume flo w rate, skip to the ne xt step. Other wise , use the Field Variable drop-do wn lists t o selec t the field v ariable t o be used in the sur face integrations . First, selec t the desir ed c ategor y in the upp er dr op-do wn list. You c an then selec t a r elated quan tity from the lo wer list. (See Field F unction D efinitions (p.2959 ) for an e xplana tion of the v ariables in the list.) 5.In the Surfaces list, cho ose the sur face(s) on which t o perform the sur face integration. 6.To create an output par amet er for the r eported v alue , click Save Output P aramet er....The Save Output Paramet er D ialog Box (p.3743 ) (Figur e 41.20: The S ave Output P aramet er D ialog Box (p.2938 )) will op en wher e you will sp ecify the name of the newly cr eated output par amet er, or o verwrite an e xisting output Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2948Reporting A lphanumer ic Dataparamet er of the same t ype. ANSY S Fluen t aut oma tically cr eates gener ic default names f or new input and output par amet ers (f or e xample , par amet er-1, par amet er-2, and so on). After the output par amet er is cr eated, it is list ed in the Paramet ers D ialog Box (p.3738 ).You c an create an y numb er of output par amet ers of this r eport type. Note If you cr eate an output par amet er fr om a sur face in tegral report and sa ve the c ase and data (wr ite), an equiv alen t report definition will b e created when y ou r ead in the c ase file. 7.Click the Comput e butt on.The c omput ed r esults ar e pr inted in the numer ic result field and also in the ANSY S Fluen t console . TheNetvalue r eported in the ANSY S Fluent c onsole c orresp onds t o the sp ecified c alculation p erformed over the list of selec ted sur faces. 8.To sa ve the c omput ed r esults t o a file , click the Write... butt on and sp ecify the filename in the r esulting Selec t File dialo g box. Note the f ollowing: •Mass a veraging “weigh ts” toward regions of higher v elocity (tha t is, regions wher e mor e mass cr osses the surface). •Flow rates reported using the Surface Integrals D ialog Box (p.3726 ) are not as accur ate as those r eported with the Flux R eports D ialog Box (p.3723 ) (descr ibed in Fluxes Through B oundar ies (p.2937 )). •The fac et and v ertex average options ar e recommended f or zero-ar ea sur faces. •The unif ormity inde x represen ts ho w a sp ecified field v ariable v aries o ver a sur face, wher e a v alue of 1 in- dicates the highest unif ormity.The unif ormity inde x can b e weigh ted b y area or mass: the ar ea-w eigh ted unif ormity inde x captur es the v ariation of the quan tity (for e xample , the sp ecies c oncentration), wher eas the mass-w eigh ted unif ormity inde x captur es the v ariation of the flux (f or e xample , the sp ecies flux). See Computing Sur face Integrals in the Theor y Guide for the equa tions used t o calcula te the unif ormity inde x. 41.8. Volume In tegration This sec tion descr ibes ho w to comput e volume in tegrals. For ma thema tical definitions of the v arious integral types, refer to Computing Volume In tegrals in the Theor y Guide . For additional inf ormation, see the f ollowing sec tion: 41.8.1. Gener ating a Volume In tegral Report 41.8.1. Gener ating a Volume In tegral Rep ort To obtain a r eport (of quan tities such as the v olume , sum, minimum, maximum, volume in tegral, volume-w eigh ted a verage, mass-w eigh ted in tegral, or mass-w eigh ted a verage) f or selec ted c ell z ones for a sp ecified field v ariable , use the Volume In tegrals D ialog Box (p.3730 ) (Figur e 41.28: The Volume Integrals D ialog Box (p.2950 )). 2949Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Volume In tegrationResults → Rep orts → Volume In tegrals Edit... Figur e 41.28: The Volume In tegrals D ialo g Box The st eps f or gener ating the r eport are as f ollows: 1.Specify which t ype of r eport you ar e interested in b y selec ting Volume ,Sum,Sum*2P i (only a vailable for 2D A xisymmetr ic cases), Maximum ,Minimum ,Volume In tegral,Volume-A verage ,Mass,Mass In- tegral, or Mass-A verage under Rep ort Type. 2.If you ar e gener ating a r eport of Volume or Mass, skip to the ne xt step. Other wise , use the Field Variable drop-do wn lists t o selec t the field v ariable t o be used in the in tegral, sum, or a veraged v olume in tegrations . First, selec t the desir ed c ategor y in the upp er dr op-do wn list. You c an then selec t a r elated quan tity from the lo wer list. (See Field F unction D efinitions (p.2959 ) for an e xplana tion of the v ariables in the list.) 3.If you ar e performing a multiphase simula tion, selec t the phase of in terest (or mix ture) from the Phase drop-do wn list. 4.In the Cell Z ones list, cho ose the z ones on which t o comput e the v olume , sum, max, min, volume in tegral, volume-w eigh ted a verage, mass in tegral, or mass-a veraged quan tity. 5.To create an output par amet er for the r eported v alue , click Save Output P aramet er....The Save Output Paramet er D ialog Box (p.3743 ) (Figur e 41.20: The S ave Output P aramet er D ialog Box (p.2938 )) will op en wher e you will sp ecify the name of the newly cr eated output par amet er, or o verwrite an e xisting output paramet er of the same t ype. ANSY S Fluen t aut oma tically cr eates gener ic default names f or new input and output par amet ers (f or e xample , par amet er-1, par amet er-2, and so on). After the output par amet er is cr eated, it is list ed in the Paramet ers D ialog Box (p.3738 ).You c an create an y numb er of output par amet ers of this r eport type. Note If you cr eate an output par amet er fr om a v olume in tegral report and sa ve the c ase and data (wr ite), an equiv alen t report definition will b e created when y ou r ead in the c ase file. 6.Click the Comput e butt on.The c omput ed r esults ar e pr inted in the numer ic result field and also in the ANSY S Fluen t console . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2950Reporting A lphanumer ic DataTheNetvalue r eported in the ANSY S Fluent c onsole c orresp onds t o the sp ecified c alculation p erformed over the list of selec ted c ell z ones . 7.To sa ve the c omput ed r esults t o a file , click the Write... butt on and sp ecify the filename in the r esulting Selec t File dialo g box. 41.9. Hist ogram Rep orts In ANSY S Fluen t, you c an pr int geometr ic and solution da ta in the c onsole (t ext) windo w in hist ogram format or plot a hist ogram in the gr aphics windo w. Graphic al displa y of hist ograms and the pr ocedur es for defining a hist ogram ar e discussed in Hist ograms (p.2875 ). The numb er of c ells, the r ange of the selec ted v ariable or func tion, and the p ercentage of the t otal numb er of c ells in the in terval will b e reported, as in the e xample b elow: 0 cells below 1.195482 (0 %) 2 cells between 1.195482 and 1.196048 (4.1666667 %) 1 cells between 1.196048 and 1.196614 (2.0833333 %) 0 cells between 1.196614 and 1.19718 (0 %) 0 cells between 1.19718 and 1.197746 (0 %) 2 cells between 1.197746 and 1.198312 (4.1666667 %) 1 cells between 1.198312 and 1.198878 (2.0833333 %) 6 cells between 1.198878 and 1.199444 (12.5 %) 9 cells between 1.199444 and 1.20001 (18.75 %) 25 cells between 1.20001 and 1.200576 (52.083333 %) 2 cells between 1.200576 and 1.201142 (4.1666667 0 cells above 1.201142 (0 %) To gener ate such a pr inted hist ogram, use the Hist ogram D ialog Box (p.3707 ). Results → Plots → Hist ogram Edit... Follow the instr uctions in Hist ograms (p.2875 ) for gener ating hist ogram plots , but click Print inst ead of Plot to cr eate the r eport. 41.10. Discr ete Phase ANSY S Fluen t allo ws you t o wr ite par ticle sta tes (p osition, velocity, diamet er, temp erature, and mass flow rate) to files a t various b oundar ies and planes (lines in 2D) using the Sample Trajec tories D ialog Box (p.3732 ) (Figur e 24.51: The S ample Trajec tories D ialog Box (p.2055 )). Information ab out discr ete phase reporting is discussed in detail in Sampling of Trajec tories (p.2054 ),Hist ogram R eporting of S amples (p.2056 ), and Summar y Reporting of C urrent Particles (p.2061 ). 41.11. S2S Inf ormation ANSY S Fluen t allo ws you t o view the v alues of the view fac tor and r adia tion emitt ed fr om one z one t o another .You will use the S2S Inf ormation D ialog Box (p.3913 ) (Figur e 13.38: The S2S Inf ormation D ialog Box (p.1540 )) to gener ate a r eport of these v alues . For details on r eporting S2S inf ormation, refer to Re- porting R adia tion in the S2S M odel (p.1539 ). 2951Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.S2S Inf ormation41.12. Ref erenc e Values You c an c ontrol the r eference values tha t are used in the c omputa tion of der ived ph ysical quan tities and non-dimensional c oefficien ts.These r eference values ar e used only f or p ostpr ocessing . Some e xamples of the use of r eference values include the f ollowing: •Force coefficien ts use the r eference area, densit y, and v elocity. In addition, the pr essur e force calcula tion uses the r eference pr essur e. •Momen t coefficien ts use the r eference length, area, densit y and v elocity. In addition, the pr essur e force calcula tion uses the r eference pr essur e. •Reynolds numb er uses the r eference length, densit y, and visc osity. •Pressur e and t otal pr essur e coefficien ts use the r eference pr essur e, densit y, and v elocity. •Entropy uses the r eference densit y, pressur e, and t emp erature. •Skin fr iction c oefficien t uses the r eference densit y and v elocity. •Heat transf er coefficien t uses the r eference temp erature. •Turbomachiner y efficienc y calcula tions use the r atio of sp ecific hea ts. For additional inf ormation, see the f ollowing sec tions: 41.12.1. Setting R eference Values 41.12.2. Setting the R eference Zone 41.12.1. Setting Ref erenc e Values To set the r eference quan tities used f or c omputing nor maliz ed flo w-field v ariables , use the Reference Values Task P age (p.3601 ) (Figur e 41.29: The R eference Values Task P age (p.2953 )). Setup → Referenc e Values Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2952Reporting A lphanumer ic DataFigur e 41.29: The Ref erenc e Values Task P age You c an sp ecify the r eference values manually or c omput e them based on v alues of ph ysical quan tities at a selec ted b oundar y zone .The r eference values t o be set ar e Area,Densit y,Enthalp y,Length , Pressur e,Temp erature,Velocity, dynamic Visc osit y, and Ratio O f Specific H eats. For 2D pr oblems , an additional quan tity,Depth , can also b e defined .This quan tity will b e used f or reporting flux es and f orces, as w ell as r elevant variables c omput ed using the Surface In tegrals D ialog Box (p.3726 ) and the Volume In tegrals D ialog Box (p.3730 ) (for e xample ,Area,Flow R ate,Mass F low Rate,Volume , and so on). You should v erify tha t the v alue and units of Depth corresponds t o the depth dimension of y our applic ation pr ior t o reporting an y of the v ariables ab ove. Imp ortant The units f or Depth are set indep enden tly fr om the units f or Length in the Set U nits D ialog Box (p.3242 ). If you w ant to comput e reference values fr om the c onditions set on a par ticular b oundar y zone , selec t the z one in the Comput e From drop-do wn list. Note, however, tha t dep ending on the b oundar y condition used , only some of the r eference values ma y be set. For e xample , the r eference length and area will not b e set b y computing the r eference values fr om a b oundar y condition; you will need t o set these manually . To set the v alues manually , simply en ter the v alue f or each under the Referenc e Values heading . 2953Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Reference Values41.12.2. Setting the Ref erenc e Zone If you ar e solving a flo w in volving multiple r eference frames or sliding meshes , you c an plot v elocities and other r elated quan tities r elative to the motion of a sp ecified “reference zone”. Choose the desir ed zone in the Referenc e Zone drop-do wn list. Changing the r eference zone allo ws you t o plot v elocities (and t otal pr essur e, temp erature, and so on) r elative to the motion of diff erent zones . See Modeling Flows with M oving R eference Frames (p.1227 ) for details ab out p ostpr ocessing of r elative quan tities . 41.13. Summar y Rep orts of C ase S ettings You ma y sometimes find it useful t o get a r eport of the cur rent settings in y our c ase. In ANSY S Fluen t, you c an list the settings f or ph ysical mo dels , boundar y conditions , ma terial pr operties, and solv er controls. This r eport allo ws you t o get an o verview of y our cur rent problem definition quick ly, inst ead of ha ving to check the settings in each dialo g box. For additional inf ormation, see the f ollowing sec tion: 41.13.1. Gener ating a Summar y Report 41.13.1. Gener ating a S ummar y Rep ort To gener ate a summar y report you will use the Input Summar y Dialog Box (p.3838 ) (Figur e 41.30: The Input Summar y Dialog Box (p.2954 )). Solution → Run C alcula tion → Input S ummar y... Figur e 41.30: The Input S ummar y D ialo g Box The st eps ar e as f ollows: 1.Selec t the inf ormation y ou w ould lik e to see in the r eport (Models ,Boundar y Conditions ,Solver C ontrols, and/or Material P roperties ) in the Rep ort Options list. 2.To pr int the inf ormation t o the ANSY S Fluen t console windo w, click the Print butt on.To sa ve the inf orm- ation t o a t ext file , click the Save... butt on and sp ecify the filename in the r esulting Selec t File dialo g box. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2954Reporting A lphanumer ic Data41.14. System Resour ce Usage You c an pr int several reports of memor y and pr ocessor usage fr om the Parallel ribbon tab . 41.14.1. Processor Inf ormation 41.14.2. Memor y Inf ormation 41.14.3. Process and M odel Timers 41.14.1. Processor Inf ormation You c an pr int out a table summar izing the pr ocessor usage on each machine tha t has c omput e pr ocesses spawned f or the cur rent session b y click ing CPU Inf o and selec ting CPU Inf o in the Parallel ribbon tab ( System group b ox). For e xample , if pr ocesses ha ve been spa wned on thr ee machines , a table similar t o the f ollowing is displa yed: --------------------------------------------------------------------------------------- | CPU | System Mem (GB) Hostname | Sock x Core Clock (MHz) Load | Total Available --------------------------------------------------------------------------------------- host23 | 8 x 8, HT 2399.85 0.07 | 129.039 89.565 host24 | 8 x 8, HT 2399.95 1.08 | 129.039 32.516 host25 | 8 x 8, HT 2400.4 3.14 | 129.039 62.531 --------------------------------------------------------------------------------------- Total | 192 - - | 387.117 184.612 --------------------------------------------------------------------------------------- Under CPU : Sock x C ore displa ys the numb er of pr ocessor so ckets, numb er of c ores p er so cket, and whether h yper-thr eading is used . Clock (MHz) is the pr ocessor sp eed. Load is the w ork load on the machine . Under System Mem (GB) : Total is the t otal sy stem memor y on the machine . Available is the a vailable sy stem memor y on the machine . You c an pr int out inf ormation ab out the GPU s available on the machine b y click ing CPU Inf o and se- lecting GPU Inf o in the Parallel ribbon tab ( System group b ox). If your machine has one or mor e suitable GPU s pr esen t, you c an use these t o acc elerate par allel pr ocessing c omputa tions as descr ibed in Using G ener al Purpose G raphics P rocessing U nits (GPGPU s) With the A lgebr aic M ultigr id (AMG) Solver (p.3093 ). CUDA visible GPUs on host01 CUDA runtime version 5000 Driver version 6000 Number of GPUs 1 0. Quadro K2100M 3 SMs 2955Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.System R esour ce Usage 0.6665 GHz 2.14748 GBytes 41.14.2. Memor y Inf ormation You c an pr int out tables summar izing memor y usage b y no de and b y host b y click ing CPU Inf o and selec ting Memor y Usage in the Parallel ribbon tab ( System group b ox). --------------------------------------------- | Virtual Mem Usage (GB)| ID | Current Peak | Page Faults --------------------------------------------- host | 0.0680117 0.0695 | 2.667e+04 n0 | 0.0855195 0.114609 | 7.229e+04 n1 | 0.0869922 0.115367 | 6.988e+04 n2 | 0.0881836 0.117613 | 7.318e+04 n3 | 0.0840781 0.11384 | 6.999e+04 --------------------------------------------- Total | 0.412785 0.53093 | 3.12e+05 --------------------------------------------- ----------------------------------------------------------------- | Virtual Mem Usage (GB) | System Mem (GB) Hostname | Current Peak | ----------------------------------------------------------------- host01 | 0.412785 0.53093 | 32.673 ----------------------------------------------------------------- Total | 0.412785 0.53093 | ----------------------------------------------------------------- Under Virtual Mem Usage (GB) : Current is the vir tual memor y usage a t the time the r eport is gener ated. Peak is the p eak vir tual memor y usage . (Linux only) U nder Resident Mem Usage (GB) : Current is the r esiden t memor y usage a t the time the r eport is gener ated. Peak is the p eak r esiden t memor y usage . Page F aults is the numb er of page faults tha t ha ve occur red. You c an use these c ommands t o plan ANSY S Fluen t jobs and machines acc ordingly .They ma y also b e useful t o diagnose p erformanc e pr oblems . 41.14.3. Process and M odel Timers You c an pr int out detailed inf ormation ab out the CPU timings f or the cur rent session as w ell as solv er timings b y click ing CPU Inf o and selec ting Time U sage in the Parallel ribbon tab ( System group b ox). The solv er timings pr esen ted ar e descr ibed in Check ing P arallel P erformanc e (p.3097 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2956Reporting A lphanumer ic Data--------------------------------------------- | CPU Time Usage (Seconds) ID | User Kernel Elapsed --------------------------------------------- host | 1.34161 0.452403 2328.63 n0 | 3.47882 0.702005 2325.88 n1 | 19.9525 1.15441 2325.87 n2 | 19.8433 0.873606 2325.87 n3 | 19.8589 0.764405 2325.86 --------------------------------------------- Total | 64.4752 3.94683 - --------------------------------------------- Model Timers (Host) Other Models Time: 2.858 sec Total Time: 2.858 sec Model Timers Other Models Time: 2.871 sec Total Time: 2.871 sec Performance Timer for 36 iterations on 4 compute nodes Average wall-clock time per iteration: 0.080 sec Global reductions per iteration: 63 ops Global reductions time per iteration: 0.000 sec (0.0%) Message count per iteration: 1955 messages Data transfer per iteration: 2.239 MB LE solves per iteration: 4 solves LE wall-clock time per iteration: 0.045 sec (56.2%) LE global solves per iteration: 4 solves LE global wall-clock time per iteration: 0.000 sec (0.4%) LE global matrix maximum size: 20 AMG cycles per iteration: 8.833 cycles Relaxation sweeps per iteration: 378 sweeps Relaxation exchanges per iteration: 383 exchanges Total wall-clock time: 2.894 sec Total CPU time: 11.185 sec 2957Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.System R esour ce UsageRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2958Chapt er 42: Field F unc tion D efinitions You must selec t flo w variables f or a numb er of tasks in ANSY S Fluen t.The v alues ar e comput ed and plac ed in t emp orary memor y tha t is allo cated f or st oring the r esults f or each c ell. For e xample , the Comput e command asso ciated with a dialo g box tha t contains the field v ariable dr op-do wn list c alcula tes the v alues of the selec ted func tion and plac es them in to temp orary storage. Node, Cell, and F acet Values (p.2959 ) and Velocity Reporting Options (p.2961 ) provide some gener al in- formation r elated t o the field v ariables . In Field Variables List ed b y Categor y (p.2963 ), the v ariables ar e listed b y categor y in Table 42.1: Pressur e and Densit y Categor ies (p.2966 ) – Table 42.17: Acoustics Categor y (p.2987 ).These tables will also indic ate when each v ariable will b e available .Alphab etical Listing of F ield Variables and Their D efinitions (p.2988 ) contains an alphab etical listing of the v ariables along with their definitions . All variables app ear as the y would in the v ariable selec tion dr op-do wn lists tha t are contained in man y of the ANSY S Fluen t dialo g boxes.Custom F ield F unctions (p.3038 ) explains ho w you c an c alcula te your o wn field func tion. 42.1. Node, Cell, and F acet Values 42.2. Velocity Reporting Options 42.3. Field Variables List ed b y Categor y 42.4. Alphab etical Listing of F ield Variables and Their D efinitions 42.5. Custom F ield F unctions 42.1. Node, Cell, and F acet Values For the f ollowing discussion, “surface” refers t o a c ollec tion of fac ets, lines or p oints tha t are created and manipula ted in the Setting U p D omain ribbon tab . In most c ases , these sur faces ar e created b y computing in tersec tions of c onstan t iso values with the domain c ells or with e xisting sur faces. For additional inf ormation, see the f ollowing sec tions: 42.1.1. Cell Values 42.1.2. Node Values 42.1.3. Facet Values 42.1.1. Cell Values ANSY S Fluen t stores most v ariables in c ells. For p ostpr ocessing , the en tire region c ontained within the cell has this v alue . A sur face cell v alue is the v alue of the c ell tha t has b een in tersec ted b y a sur face facet or line , or tha t contains a sur face point. Since sur face fac ets and lines ar e created fr om the in ter- section of iso values and the e xisting mesh c ells, this is a unique definition. Typic ally, the c ell v alue on a boundar y is the v alue in the c ell adjac ent to the b oundar y. For fac e-only func tions lik e Wall S hear Stress, the c ell v alue is the ar ea-w eigh ted a verage fr om the fac e values tha t define tha t cell as c0. This v alue is used f or the c ell v alues of p ostpr ocessing sur faces. But for b oundar y fac es, the c ell v alue actually displa ys/uses the e xact fac e value . 2959Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.42.1.2. Node Values Node v alues ar e explicitly defined or obtained b y weigh ted a veraging of the c ell da ta.Various boundar y conditions imp ose v alues of field v ariables a t the domain b oundar ies, so mesh no de v alues on these b oundar y zones ar e obtained b y simple a veraging of the adjac ent boundar y fac e da ta. In addition, for se veral variables (f or e xample , node c oordina tes or no de displac emen ts for the str uctural model) e xplicit no de v alues ar e available a t all no des. Computa tion of no de v alues is p erformed in t wo steps: 1.Values a t all no des ar e initializ ed t o the w eigh ted a verage of the sur rounding c ell v alues .The w eigh ts ar e the in verses of the c ell v olumes tha t neighb or the no des. 2.At boundar ies, these no de v alues ar e overwritten with the simple a verage of the b oundar y fac e values . Variables f or which e xplicit no de v alues ar e available a t boundar ies ar e indic ated b y bnv in Table 42.1: Pressur e and Densit y Categor ies (p.2966 ) – Table 42.17: Acoustics Categor y (p.2987 ). For e xample , in Figur e 42.1: Computing N ode Values (p.2960 ), the v alue a t no de will b e comput ed from the w eigh ted a verage of the v alues in the sur rounding c ells ( — ).The v alue a t no de will be comput ed fr om the simple a verage of the b oundar y fac es ( and ) if ther e ar e explicit boundar y values a vailable f or the v ariable in question. Figur e 42.1: Computing N ode Values 42.1.2.1. Vertex Values for P oints That A re Not Mesh N odes The v alues of the no des on sur faces ar e linear ly in terpolated fr om the mesh no de da ta. For z one surfaces, the no des on the sur face and the z one c orrespond; ther efore, the v alues ar e iden tical. For surfaces tha t are not z one sur faces (f or e xample , isosur faces, plane sur faces, and so on), the no de values ar e in terpolated fr om mesh no des on the c ell fac es in tersec ted b y the p ostpr ocessing sur face. For p oint sur faces and str uctural p oint sur faces, the v alue is in terpolated fr om all the mesh no des of the c ell c ontaining the p oint. 42.1.3. Facet Values Facets c an b e created on pr eprocessing sur faces and p ostpr ocessing sur faces. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2960Field F unction D efinitions42.1.3.1. Facet Values on Z one S urfaces The in terior fac ets on a z one sur face ar e asso ciated with t wo cells (c0 and c1).The v alues of a sp ecified variable on such fac ets ar e comput ed as the ar ithmetic a verage of the t wo cell v alues of the selec ted variable . The b oundar y fac et v alues of a pr imar y field v ariables on a z one sur face ar e tak en fr om the sp ecified boundar y conditions .The b oundar y values of dep enden t variables ar e comput ed fr om the adjac ent cell v alues (v ersus using the v alue of the pr imar y variable sp ecified a t the b oundar y). For e xact values of dep enden t variables a t the b oundar ies, define a cust om field func tion sp ecifying the b oundar y conditions as the pr imar y variables . For mor e inf ormation on cust om field func tions , see Custom F ield Functions (p.3038 ). 42.1.3.2. Facet Values on P ostpr ocessing S urfaces Each fac et on a p ostpr ocessing sur face is asso ciated with a c ell.The v alues of a sp ecified v ariable on facets ar e the same as the c ell v alues of the selec ted v ariable in the asso ciated c ells (this includes iso surfaces, planes , lines , points, rakes, quadr ic, and so on). 42.2. Velocity Rep orting Options The f ollowing metho ds ar e available f or reporting v elocities: •Cartesian v elocities: These v elocities ar e based on the C artesian c oordina te sy stem used b y the geometr y.To report Cartesian v elocities , selec t X Velocity,Y Velocity, or Z Velocity.This is the most c ommon t ype of velocity reported. •Cylindr ical velocities: These v elocities ar e the axial, radial, and tangen tial c omp onen ts based on the f ollowing c oordina te systems: –For axisymmetr ic pr oblems , in which the r otation axis must b e the axis , the direction is the axial dir- ection and the direction is the r adial dir ection. (If you mo del axisymmetr ic swir l, the swir l dir ection is the tangen tial dir ection.) –For 2D pr oblems in volving a single c ell z one , the direction is the axial dir ection, and its or igin is sp ecified in the Fluid D ialog Box (p.3457 ). –For 3D pr oblems in volving a single c ell z one , the c oordina te sy stem is defined b y the r otation axis and origin sp ecified in the Fluid D ialog Box (p.3457 ). –For pr oblems in volving multiple z ones (f or e xample , multiple r eference frames or sliding meshes), the coordina te sy stem is defined b y the r otation axis sp ecified in the Fluid D ialog Box (p.3457 ) (or Solid D ialog Box (p.3467 )) for the “reference zone”.The r eference zone is chosen in the Reference Values Task P age (p.3601 ), as descr ibed in Reference Values (p.2952 ). Recall tha t for 2D pr oblems , you will sp ecify only the axis or igin; the direction is alw ays the axial dir ection. For all of the ab ove definitions of the c ylindr ical coordina te sy stem, positiv e radial v elocities p oint radially out fr om the r otation axis , positiv e axial v elocities ar e in the dir ection of the r otation axis 2961Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Velocity Reporting Optionsvector, and p ositiv e tangen tial v elocities ar e based on the r ight-hand r ule using the p ositiv e rotation axis. To report cylindr ical velocities , selec t Axial Velocity,Radial Velocity, and so on. Figur e 42.2: Cylindr ical Velocity Comp onen ts in 3D , 2D, and A xisymmetr ic D omains (p.2962 ) illustr ates the c ylindr ical velocities available f or diff erent types of domains . For 3D pr oblems , you c an r eport axial, radial, and tangen tial velocities . For 2D pr oblems , radial and tangen tial v elocities ar e available . For axisymmetr ic pr oblems , you c an r eport axial and r adial v elocities , and , if y ou ar e mo deling axisymmetr ic swir l, you c an also report the swir l velocity (which is equiv alen t to the tangen tial v elocity). Figur e 42.2: Cylindr ical Velocity Comp onen ts in 3D , 2D, and A xisymmetr ic D omains •Relative velocities: These v elocities ar e based on the c oordina te sy stem and motion of a mo ving r eference frame .They are useful when y ou ar e mo deling y our flo w using a mo ving r eference frame , a mixing plane , multiple r eference frames , or sliding meshes . (See Modeling F lows with M oving R eference Frames (p.1227 ) for inf ormation ab out mo deling flo w in mo ving z ones .) To report relative velocities , selec t Rela tive X Velocity, Rela tive Y Velocity,Rela tive Radial Velocity, and so on. (Note tha t you c an r eport relative velocities f or both C artesian and c ylindr ical comp onen ts.) If you ar e using a single mo ving r eference frame , the r elative velocity values will b e reported with respect to the mo ving fr ame . If you ar e using multiple r eference frames , mixing planes , or sliding meshes , you will need t o sp ecify the fr ame t o which y ou w ant the v elocities t o be relative by choosing the appr opriate cell z one as the Referenc e Zone in the Reference Values Task P age (p.3601 ) (see Reference Values (p.2952 )).The axis of r otation f or each c ell z one is defined in the asso ciated Fluid D ialog Box (p.3457 ) or Solid D ialog Box (p.3467 ). (See Specifying the R otation A xis (p.856) or Spe- cifying the R otation A xis (p.860) for details .) Note tha t if y our pr oblem do es not in volve an y mo ving z ones , relative and absolut e velocities will be equiv alen t. Note tha t relative velocities c an also b e used t o comput e stagna tion quan tities (t otal pr essur e and t otal temp erature), and tha t the c ylindr ical coordina te sy stems descr ibed in the sec ond it em ab ove ar e used for defining the Axial C oordina te and Radial C oordina te as w ell. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2962Field F unction D efinitions42.3. Field Variables List ed b y Categor y The field v ariables a vailable in each c ategor y are summar ized in the f ollowing tables: •Table 42.1: Pressur e and Densit y Categor ies (p.2966 ) •Table 42.2: Velocity Categor y (p.2967 ) •Table 42.3: Temp erature,Radia tion , and Solidific ation/M elting Categor ies (p.2968 ) •Table 42.4: Turbulenc e Categor y (p.2969 ) •Table 42.5: Species ,Reac tions ,Pdf, and Premix ed C ombustion Categor ies (p.2972 ) •Table 42.6: NOx,Soot, and Stead y|Unstead y Statistics Categor ies (p.2974 ) •Table 42.7: Phases ,Discr ete Phase M odel,Granular P ressur e,Granular Temp erature, and Wall F ilm Categor ies (p.2976 ) •Table 42.8: Properties Categor y (p.2979 ) •Table 42.9: Euler ian Wall F ilm Categor y (p.2979 ) •Table 42.10: Sensitivities Categor y (p.2981 ) •Table 42.11: Wall F luxes,User D efined Sc alars , and User D efined M emor y Categor ies (p.2982 ) •Table 42.3: Temp erature,Radia tion , and Solidific ation/M elting Categor ies (p.2968 ) •Table 42.13: Mesh Categor y (Turbomachiner y-Specific Variables) (p.2984 ) •Table 42.14: Residuals Categor y (p.2985 ) •Table 42.15: Derivatives Categor y (p.2985 ) •Table 42.16: Potential Categor y (p.2986 ) •Table 42.17: Acoustics Categor y (p.2987 ) •Table 42.18: Structure Categor y (p.2988 ) In these tables , the f ollowing r estrictions apply t o mar ked v ariables: available only f or 2D flo ws 2d available only f or 2D axisymmetr ic flo ws (with or without swir l)2da available only f or 2D axisymmetr ic swir l flo ws 2dasw available only f or 3D flo ws 3d available only with da ta fr om the adjoin t solv er adj available only f or adjoin t calcula tions tha t use the dissipa tion stabiliza tion schemeadis available only when the ener gy adjoin t equa tion is solv edaen available only with the A ungier-R edlich-K wong real gas mo delark available only when cr eated using the Acoustic Sources FFT D ialog Box (p.3652 ) or r elated t ext commandsasff t available only with the ac oustics w ave equa tion mo delawe available only f or br oadband noise sour ce modelsbns node v alues a vailable a t boundar ies bnv available only f or c ompr essible flo w cmp available only in the densit y-based solv ers cpl 2963Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Field Variables List ed b y Categor yavailable only f or c ell v alues ( Node Values option tur ned off )cv available only when the DDPM mo del is used ddpm available when the turbulenc e mo del includes the DES turbulenc e mo deldes not a vailable with full multic omp onen t diffusiondil available only f or d ynamic mesh c alcula tions dm available only when the discr ete or dina tes radia tion mo del is useddo available only f or c oupled discr ete phase calcula tionsdpm available only when M ean Values ar e enabled in the DPM dialo g boxdpmean available only when RMS Values ar e enabled in the DPM dialo g boxdprms available only when the discr ete transf er radia tion mo del is useddtrm available only with the Ff owcs Williams and Hawkings ac oustics mo delfwh available only f or ener gy calcula tions e available only with the E lectrochemic al Reactions mo delechem available only with the EDC mo del f or turbulenc e-chemistr y interactionedc available only when the E uler ian multiphase model is usedemm available only with the E uler ian Wall F ilm modelewf available only with the enhanc ed w all treatmen tewt available f or fac e values fv available only if a gr anular phase is pr esen t gran available only when the mix ture contains w ater h2o available only f or hanging no de adaption hn available only when the ideal gas la w is enabled f or densit yid available when one of the - turbulenc e models is usedke available when the - - mo del is used kklo available when one of the - turbulenc e models is usedkw available when the LES turbulenc e mo del is usedles Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2964Field F unction D efinitionsavailable only when the Lagr angian w all film model is usedlwf available only when the M onte Carlo mo del is usedmc available only when the melting and solidific ation mo del is usedmelt available only when the multiphase mix ture model is usedmix available only f or multiphase mo dels mp available only f or p orous c ell z ones with the non-equilibr ium ther mal mo del enablednetm available only f or NO x calcula tions nox uses e xplicit no de v alue func tion nv uses e xplicit no de v alue solutions nvs available only when o verset meshing is used os available only when the P-1 r adia tion mo del is usedp1 available only f or non-pr emix ed c ombustion calcula tionspdf available only f or pr emix ed c ombustion calcula tionspmx available only when the p otential equa tion is solv edpot available only f or par tially pr emix ed combustion c alcula tionsppmx available only when the R osseland r adia tion model is usedr available only f or radia tion hea t transf er calcula tionsrad available only f or finit e-rate reactions rc available only f or the r eal gas mo dels rg available when the R eynolds str ess turbulenc e model is usedrsm available only when the sur face-to-sur face radia tion mo del is useds2s available when the S palar t-Allmar as turbulenc e model is usedsa available when the turbulenc e mo del includes Scale-A daptiv e Simula tion (SAS)sas available when the turbulenc e mo del includes the S tress-B lended E ddy Simula tion (SBES) turbulenc e mo delsbes available when the turbulenc e mo del includes the S hielded D etached E ddy Simula tion (SDES) turbulenc e mo delsdes 2965Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Field Variables List ed b y Categor yavailable only in the pr essur e-based solv er seg available only when the solar mo del is used sol available only f or so ot c alcula tions soot available only f or sp ecies c alcula tions sp available only f or sur face reactions sr available when the Transition SST mo del is usedsst available only with da ta sampling f or tr ansien t statisticsstat available only f or stiff chemistr y calcula tions stcm available only when a str uctural mo del is selec tedstrc available only f or turbulen t flo ws t available only when thin w alls ar e pr esen t th available only f or tr ansien t flo w calcula tions trn available only when a turb omachiner y topology has b een definedturb o available only when a user-defined memor y is usedudm available only when a user-defined sc alar is useduds available only f or visc ous flo ws v available only f or VOF-t o-DPM mo del tr ansition calcula tionsvof-dpm Table 42.1: Pressur e and Densit y Categor ies Variable Categor y Static P ressur e (bn v) Pressur e... Pressur e Coefficien t Dynamic P ressur e Absolut e Pressur e (bn v) Total P ressur e (bn v) Rela tive Total P ressur e Capillar y-Pressur e (emm) Densit y Densit y... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2966Field F unction D efinitionsVariable Categor y Densit y All Table 42.2: Velocity Categor y Variable Categor y Velocity M agnitude (bn v) Velocity... X Velocity (bn v) Y Velocity (bn v) Z Velocity (3d , bnv) Swirl Velocity (2dasw , bnv) Axial Velocity (2da or 3d) Radial Velocity Stream F unc tion (2d) Tangen tial Velocity Mach N umb er (id or r g) Rela tive Velocity M agnitude (bn v) Rela tive X Velocity (bn v) Rela tive Y Velocity (bn v) Rela tive Z Velocity (3d , bnv) Rela tive Axial Velocity (2da) Rela tive Radial Velocity (2da) Rela tive Swirl Velocity (2dasw , bnv) Rela tive Tangen tial Velocity Rela tive M ach N umb er (id or r g) Mesh X-V elocity (nv) Mesh Y-V elocity (nv) Mesh Z-V elocity (3d , nv) Velocity Angle Rela tive Velocity Angle Vorticit y M agnitude (v) 2967Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Field Variables List ed b y Categor yVariable Categor y Helicit y (v, 3d) X-V orticit y (v, 3d) Y-V orticit y (v, 3d) Z-Vorticit y (v, 3d) Cell Re ynolds N umb er (v) Cell C onvective Cour ant Numb er (seg) Cell A coustic C our ant Numb er (cmp , seg) Preconditioning Ref erenc e Velocity (cpl) Table 42.3: Temp erature,Radia tion , and Solidific ation/M elting Categor ies Variable Categor y Static Temp erature (e, bnv, nv) Temp erature... Total Temp erature (e, nv) Sensible E nthalp y (e, nv) Enthalp y (e, nv) Rela tive Total Temp erature (e) Rothalp y (e, nv) Fine Sc ale Temp erature (edc ,e) Wall Temp erature (fv, e, v) Wall Temp erature (Thin) (th, fv, e, v) Wall A djac ent Temp erature (fv, e) Total E nthalp y (e) Total E nthalp y D eviation (e) Entropy (e) Total E nergy (e) Internal E nergy (e) Non-E quilibr ium Thermal M odel S our ce (e, netm) Absor ption C oefficien t (r, p1, do, mc, or dtr m) Radia tion... Scattering C oefficien t (r, p1, do, or mc) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2968Field F unction D efinitionsVariable Categor y Refr active Inde x (do or mc) Radia tion Temp erature (p1,do , or mc) Inciden t Radia tion (p1, do, or mc) Inciden t Radia tion (B and n) (p1 (non-gr ay), do (non-gr ay), or mc (non-gr ay)) Volumetr ic A bsorb ed R adia tion (p1, do, or mc) Volumetr ic E mitt ed R adia tion (p1, do, or mc) Wall Ir radia tion F lux.N ormaliz ed S td D evi- ation (mc) Radia tion In tensit y.Normaliz ed S td D evi- ation (mc) Surface Clust er ID (fv, s2s) Liquid F raction (melt) Solidific ation/ Melting Contact Resistivit y (fv, melt) X Pull Velocity (melt (if c alcula ted)) Y Pull Velocity (melt (if c alcula ted)) Z Pull Velocity (melt (if c alcula ted), 3d) Axial P ull Velocity (melt (if c alcula ted), 2da) Radial P ull Velocity (melt (if c alcula ted), 2da) Swirl Pull Velocity (melt (if c alcula ted), 2dasw) Table 42.4: Turbulenc e Categor y Variable Categor y Turbulen t Kinetic E nergy (k) (ke, kw, kklo, sst, rsm, les; sbes, sdes , bnv, nv, or emm)Turbulenc e... Laminar K inetic E nergy (kklo) Total F luctuation E nergy (kklo) Turbulen t In tensit y (ke, kw, kklo, sst, rsm, les, sbes, sdes) Intermitt enc y (sst , kw, sas, des , sbes, sdes) 2969Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Field Variables List ed b y Categor yVariable Categor y Intermitt enc y Effective (sst , sbes (with Transition SST only), sdes (with Transition SST only)) Momen tum Thick ness Re (sst , sbes (with Transition SST only), sdes (with Transition SST only)) Geometr ic Roughness H eigh t (sst , sbes (with Transition SST only), sdes (with Transition SST only)) UU Re ynolds S tress (rsm; emm) VV Re ynolds S tress (rsm; emm) WW Re ynolds S tress (rsm; emm) UV Re ynolds S tress (rsm; emm) UW Re ynolds S tress (rsm, 3d; emm) VW Re ynolds S tress (rsm, 3d; emm) Resolv ed UV Re ynolds S tress (sas , des , sbes, sdes , les) Resolv ed UW Re ynolds S tress (sas , des , sbes, sdes , les) Resolv ed VW Re ynolds S tress (sas , des , sbes, sdes , les) Turbulen t Dissipa tion R ate (E psilon) (ke, kw, kklo, sst, sbes, sdes , or rsm; bnv (k-epsilon model only), nv (k-epsilon mo del only), or emm) Specific D issipa tion R ate (Omega) (kw, kklo, sst, sbes, sdes , rsm) Produc tion of k (ke, kw, kklo, sst, rsm, les; emm) Produc tion of laminar k (kklo) Modified Turbulen t Visc osit y (sa, des) Turbulen t Visc osit y (sa, ke, kw, kklo, sst, sbes, sdes , rsm, sas, des , les) Turbulen t Visc osit y (lar ge-sc ale) (kklo) Turbulen t Visc osit y (small-sc ale) (kklo) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2970Field F unction D efinitionsVariable Categor y Effective Visc osit y (sa, ke, kw, kklo, sst, sbes, sdes , rsm, des; emm) Turbulen t Visc osit y Ratio (ke, kw, kklo, sst, sbes, sdes , rsm, sa, des , les; emm) LES S ubgrid Turbulen t Visc osit y (les) Subgrid K inetic E nergy (les) Subgrid Turbulen t Visc osit y (les) Subgrid Turbulen t Visc osit y Ratio (les) Subgrid E ffective Visc osit y (les) Subgrid F ilter L ength (les) Subgrid Test-F ilter L ength (les) Subgrid D issipa tion R ate (les) Subgrid D ynamic Visc osit y Const (les) Subgrid D ynamic P randtl N umb er (les) Subgrid D ynamic Sc of S pecies (les) Subt est K inetic E nergy (les) Effective Thermal C onduc tivit y (t, e) Effective Prandtl N umb er (t, e) Wall Ystar (fv, ke, kw, kklo, sst, sbes, sdes , rsm, les) Wall Yplus (fv, t) Turbulen t Re ynolds N umb er (Re_y) (ke, kw, kklo, sst, sbes, sdes , rsm; ewt) Rela tive Length Sc ale (DES) (des) DES TKE D issipa tion M ultiplier (des) Curvature Correction F unc tion fr (sa, ke, kw, sst, sbes, sdes , sas, des) Shielding F unc tion f or SBES or SDES (sbes, sdes) Normaliz ed Q C riterion (des , sas, les, sbes, sdes) 2971Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Field Variables List ed b y Categor yVariable Categor y Q C riterion (des , sas, les, sbes, sdes) Lamb da 2 C riterion (des , sas, les, sbes, sdes) Table 42.5: Species ,Reac tions ,Pdf , and Premix ed C ombustion Categor ies Variable Categor y Mass fr action of species-n (sp, pdf, or ppmx; nv)Species ... Mole fr action of species-n (sp, pdf, or ppmx) Molar C onc entration of species-n (sp, pdf, or ppmx) Lam D iff C oef of species-n (sp, dil) Eff D iff C oef of species-n (t, sp, dil) Thermal D iff C oef of species-n (sp) Enthalp y of species-n (sp) species-n Sour ce Term (rc, cpl) Surface D eposition R ate of species-n (sr) Surface Coverage of species-n (sr) Porous D eposition R ate of species-n (sr) Rela tive Humidit y (sp, pdf, or ppmx; h2o) Time S tep Sc ale (sp, stcm) Fine Sc ale M ass fr action of species-n (edc) Cell Time Sc ale (edc) EDC C ell Volume F raction (edc) DRG Reduc ed N umb er of S pecies (sp) Reac tor N et Z one ID (sp) Reac tor N et Temp erature (sp) Reac tor N et M ass fr action of species-n (sp) Surface Corrosion R ate of species-n (echem) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2972Field F unction D efinitionsVariable Categor y Rate of Reac tion-n (rc) Reac tions ... Kinetic R ate of Reac tion-n (rc) Turbulen t Rate of Reac tion-n (rc, t) Heat of Reac tion (e, rc) Net Reac tion R ate of Species-n (edc , stcm) DRG Reduc ed N umb er of Reac tions (sp) Echem Reac tion R ate of Reac tion-n (echem) Mean M ixture Fraction (pdf or ppmx; nv) Pdf... Secondar y M ean M ixture Fraction (pdf or ppmx; nv) Mixture Fraction Varianc e (pdf or ppmx; nv) Secondar y M ixture Fraction Varianc e (pdf or ppmx; nv) Fvar P rod (pdf or ppmx) Fvar2 P rod (pdf or ppmx) Scalar D issipa tion (pdf or ppmx) Heat Release R ate (pdf or ppmx) PDF Table A diaba tic E nthalp y (pdf or ppmx) PDF Table H eat Loss/G ain (e, pdf or ppmx) Progress Variable (pmx or ppmx; nv) Premix edCombustion... Progress Variable Varianc e (ppmx; nv) Scalar M ass F raction of species-n (ppmx) Forward Reac tion R ate of PDF scalar-n (ppmx) Reverse Reac tion R ate of PDF scalar-n (ppmx) Damk ohler N umb er (pmx or ppmx) Stretch F actor (pmx or ppmx) Turbulen t Flame S peed (pmx or ppmx) Static Temp erature (pmx or ppmx) 2973Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Field Variables List ed b y Categor yVariable Categor y Produc t Formation R ate (pmx or ppmx) Laminar F lame S peed (pmx or ppmx) Critical S train R ate (pmx or ppmx) Adiaba tic F lame Temp erature (pmx or ppmx) Unbur nt Fuel M ass F raction (pmx or ppmx) Table 42.6: NOx,Soot, and Stead y|Unstead y Statistics Categor ies Variable Categor y Mass fr action of NO (no x) NOx... Mass fr action of HCN (no x) Mass fr action of NH3 (no x) Mass fr action of N2O (no x) Mole fr action of NO (no x) Mole fr action of HCN (no x) Mole fr action of NH3 (no x) Mole fr action of N2O (no x) NO D ensit y (no x) HCN D ensit y (no x) NH3 D ensit y (no x) N2O D ensit y (no x) Varianc e of Temp erature (no x) Varianc e of S pecies (no x) Varianc e of S pecies 1 (no x) Varianc e of S pecies 2 (no x) Rate of NO (no x) Rate of Thermal NO (no x) Rate of P rompt NO (no x) Rate of F uel NO (no x) Rate of N2OP ath NO (no x) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2974Field F unction D efinitionsVariable Categor y Rate of Rebur n NO (no x) Rate of SNCR NO (no x) Rate of USER NO (no x) Average N umb er of P articles in S oot A ggr eg- ate (soot)Soot... Conc entration of soot species-n (soot) Mass fr action of so ot (soot) Mass fr action of N uclei (soot) Mole fr action of so ot (soot) Normaliz ed C onc entration of N uclei (soot) Normaliz ed S oot A ggr ega tion M omen ts (soot) Normaliz ed so ot momen ts (soot) Primar y Particle D iamet er (soot) Rate of C oagula tion (soot) Rate of N uclei (soot) Rate of N uclea tion (soot) Rate of O xida tion (soot) Rate of S oot (soot) Rate of S oot M ass N uclea tion (soot) Rate of S urface Growth (soot) Site fr action of soot species-n (soot) Soot D ensit y (soot) Soot M ean D iamet er (soot) Soot S urface Area (soot) Soot Volume fr action (soot) Accum DPM P arcels in C ell (dpm, stat) Stead y|Unstead y DPM Statistics ... Accum DPM P articles in C ell (dpm, stat) Mean DPM n (dpm, stat) 2975Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Field Variables List ed b y Categor yVariable Categor y RMS DPM n (dpm, stat) Mean n (sta t) Stead y|Unstead y Statist- ics... Mean- cff_n (sta t) RMSE n (sta t) RMSE- cff_n (sta t) Table 42.7: Phases ,Discr ete Phase M odel,Granular P ressur e,Granular Temp erature, and Wall Film Categor ies Variable Categor y Heat of H eterogeneous Reac tion Phase In teraction... Mass Transf er R ate n Saturation Temp erature n Latent Heat n Volume fr action (mp) Phases ... Lump ID (vof-dpm) Lump D etection... Lump D iamet er (vof-dpm) Lump D ensit y (vof-dpm) Lump A sph. by Rad. Std. Dev. (vof-dpm) Lump A sph. by Or tho gonalit y (vof-dpm) Lump X, Y, Z C oordina te (vof-dpm) Lump Temp erature (vof-dpm, e) Lump E nthalp y (vof-dpm, e) Lump P ressur e (vof-dpm, e) DPM E rosion R ate (G ener ic) (dpm, cv, fv) Discr ete Phase Variables ... DPM E rosion R ate (F innie) (dpm, cv, fv) DPM E rosion R ate (M cLaur y) (dpm, cv, fv) DPM E rosion R ate (O ka) (dpm, cv, fv) DPM E rosion R ate (Wall S hear) (dpm, cv, fv, gran) DPM A ccretion (dpm, cv, fv) DPM Volume F raction (dpm, dpmean) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2976Field F unction D efinitionsVariable Categor y DPM P arcels in C ell (dpm, dpmean) DPM P articles in C ell (dpm, dpmean) DPM N umb er D ensit y (dpm, dpmean) DPM C ollision R ate (dpm) DPM X Velocity (dpm, dpmean) DPM Y Velocity (dpm, dpmean) DPM Z Velocity (dpm, dpmean) DPM D iamet er (dpm, dpmean) DPM D ensit y (dpm, dpmean) DPM Temp erature (dpm, dpmean) DPM S pecific H eat (dpm, dpmean) DPM D20 (dpm, dpmean) DPM D30 (dpm, dpmean) DPM D32 (dpm, dpmean) DPM D43 (dpm, dpmean) DPM G ranular Temp erature (ddpm, gran) DPM C onc of (dpm, dpmean, sp) DPM RMS X Velocity (dpm, dpr ms) DPM RMS Y Velocity (dpm, dpr ms) DPM RMS Z Velocity (dpm, dpr ms) DPM RMS D iamet er (dpm, dpr ms) DPM RMS Temp erature (dpm, dpr ms) DPM A bsor ption C oefficien t (dpm, rad) DPM E mission (dpm, rad) DPM Sc attering (dpm, rad) DPM C onc entration (dpm) DPM Wall X F orce (dpm) 2977Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Field Variables List ed b y Categor yVariable Categor y DPM Wall Y Force (dpm) DPM Wall Z F orce (dpm) DPM Wall N ormal P ressur e (dpm) DPM M ass S our ce (dpm) Discr ete Phase S our ces... DPM X M omen tum S our ce (dpm) DPM Y M omen tum S our ce (dpm) DPM Z M omen tum S our ce (dpm, 3d) DPM S wirl Momen tum S our ce (dpm, 2dasw) DPM S ensible E nthalp y Sour ce (dpm, e, rc) DPM E nthalp y Sour ce (dpm, e) DPM Bur nout (dpm, sp, e) DPM E vaporation/D evolatiliza tion (dpm, sp, e) DPM species-n Sour ce (dpm, sp, e) Granular P ressur e (emm, gran) Granular P ressur e... Granular Temp erature (emm, gran) Granular Temp erature... Wall F ilm H eigh t (dpm, lwf ) Wall F ilm... Wall F ilm Impingemen t Mass F lux (dpm, lwf ) Wall F ilm F ace Pressur e (dpm, lwf ) Wall F ilm M ass (dpm, lwf ) Wall F ilm Temp erature (dpm, lwf ) Wall F ilm H eat Flux (dpm, lwf ) Wall F ilm X-V elocity (dpm, lwf ) Wall F ilm Y-V elocity (dpm, lwf ) Wall F ilm Z-V elocity (dpm, lwf, 3d) Wall F ilm Velocity M agnitude (dpm, lwf ) Wall L eidenfr ost Temp erature (dpm, lwf ) Wall C overage (dpm, lwf ) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2978Field F unction D efinitionsVariable Categor y Film M ass F raction of material-i (dpm, lwf) Table 42.8: Properties Categor y Variable Categor y Molecular Visc osit y (v) Properties ... Diamet er (mix, emm) Granular C onduc tivit y (mix, emm, gran) Thermal C onduc tivit y (e, v) Specific H eat (Cp) (e) Specific H eat Ratio (gamma) (id) Gas C onstan t (R) (id or r g) Molecular P randtl N umb er (e, v) Mean M olecular Weigh t (seg , pdf) Sound S peed (id or r g) Compr essibilit y Factor (rg) Reduc ed Temp erature (ark) Reduc ed P ressur e (ark) Critical Temp erature (ark, spe) Critical P ressur e (ark, spe) Acentric Factor (ark,sp e) Critical S pecific Volume (ark,sp e) Spino dal Temp erature (ark) Electric C onduc tivit y (pot) Table 42.9: Euler ian Wall F ilm Categor y Variable Categor y Film Thick ness (3d , ewf ) Euler ian Wall F ilm... Film M ass (3d , ewf ) Film Temp erature (3d , ewf ) Film X-V elocity (3d , ewf ) 2979Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Field Variables List ed b y Categor yVariable Categor y Film Y-V elocity (3d , ewf ) Film Z-V elocity (3d , ewf ) Film Velocity M agnitude (3d , ewf ) Film C overage (3d , ewf ) Film E ffective Pressur e (3d , ewf ) Film S urface X-V elocity (3d , ewf ) Film S urface Y-V elocity (3d , ewf ) Film S urface Z-V elocity (3d , ewf ) Film S urface Velocity M agnitude (3d , ewf ) Film S urface Temp erature (3d , ewf ) Film P assiv e Sc alar (3d , ewf ) Film C our ant Numb er (3d , ewf ) Film Weber N umb er (3d , ewf ) Film S tripped M ass (3d , ewf ) Film S tripped D iam (3d , ewf ) Film DPM M ass S our ce (3d , ewf , dpm) Film DPM E nergy Sour ce (3d , ewf , dpm) Film DPM X-M omen tum S our ce (3d , ewf , dpm) Film DPM Y-M omen tum S our ce (3d , ewf , dpm) Film DPM Z-M omen tum S our ce (3d , ewf , dpm) Film X-M omen tum S our ce (3d , ewf ) Film Y-M omen tum S our ce (3d , ewf ) Film S epar ated M ass (3d , ewf ) Film S epar ated D iam (3d , ewf ) Film S epar ation R ate (3d , ewf ) Film P hase C hange R ate (3d , ewf ) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2980Field F unction D efinitionsVariable Categor y Film Outflo w M ass (3d , ewf ) Film S econdar y Phase M ass (3d , ewf ) Film S econdar y Phase C ollec tion C oef (3d , ewf ) Table 42.10: Sensitivities Categor y Variable Categor y Magnitude of S ensitivit y to Body Forces (Cell Values) (adj)Sensitivities ... Sensitivit y to Body Force X-C omp onen t (C ell Values) (adj) Sensitivit y to Body Force Y-C omp onen t (C ell Values) (adj) Sensitivit y to Body Force Z-C omp onen t (C ell Values) (adj , 3d) Sensitivit y to M ass S our ces (C ell Values) (adj) Sensitivit y to Energy Sour ces (C ell Values) (adj, aen) Artificial D issipa tion (adj , adis) Sensitivit y to Visc osit y (adj) Shap e Sensitivit y M agnitude (adj) Normal S hap e Sensitivit y (adj) Normal Optimal D isplac emen t (adj) log10(S hap e Sensitivit y M agnitude) (adj) Shap e Sensitivit y X-C omp onen t (adj) Shap e Sensitivit y Y-C omp onen t (adj) Shap e Sensitivit y Z-C omp onen t (adj , 3d) Sensitivit y to Boundar y X-V elocity (adj) Sensitivit y to Boundar y Y-V elocity (adj) Sensitivit y to Boundar y Z-V elocity (adj , 3d) Sensitivit y to Boundar y Pressur e (adj) 2981Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Field Variables List ed b y Categor yVariable Categor y Sensitivit y to Boundar y Temp erature (adj , aen) Sensitivit y to Boundar y Heat Flux (adj , aen) Sensitivit y to Flow Blo ckage (adj) Adjoin t Local S olution M arker (adj) Table 42.11: Wall F luxes,User D efined Sc alars , and User D efined M emor y Categor ies Variable Categor y Wall S hear S tress (v, emm, fv) Wall F luxes... X-W all S hear S tress (v, emm, fv) Y-W all S hear S tress (v, emm, fv) Z-W all S hear S tress (v, 3d, emm, fv) Axial-W all S hear S tress (2da, fv) Radial-W all S hear S tress (2da, fv) Swirl-Wall S hear S tress (2dasw , fv) Skin F riction C oefficien t (v, emm, fv) Total S urface Heat Flux (e, v, fv) Radia tion H eat Flux (fv, rad) Solar H eat Flux (sol, fv) Absorb ed R adia tion F lux (B and-n) (do , fv) Absorb ed Visible S olar F lux (sol, fv) Absorb ed IR S olar F lux (sol, fv) Reflec ted R adia tion F lux (B and-n) (do , fv) Reflec ted Visible S olar F lux (sol, fv) Reflec ted IR S olar F lux (sol, fv) Transmitt ed R adia tion F lux (B and-n) (do , fv) Transmitt ed Visible S olar F lux (sol, fv) Transmitt ed IR S olar F lux (sol, fv) Beam Ir radia tion F lux (B and-n) (do , fv) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2982Field F unction D efinitionsVariable Categor y Surface Inciden t Radia tion (do , dtrm, or s2s; fv) Surface Heat Transf er C oef. (e, v, fv) Wall F unc . Heat Tran. Coef. (e, v, fv) Wall A djac ent Heat Transf er C oef. (e, fv) Surface Nusselt N umb er (e, v, fv) Surface Stanton N umb er (e, v, fv) Scalar-n (bn v, uds) User D efined Sc alars ... Diffusion C oef. of Sc alar-n (bn v, uds) User M emor y (bn v, udm) User D efined M emor y... User N ode M emor y (bn v, udm) Table 42.12: Cell Inf o and Mesh Categor ies Variable Categor y Active Cell P artition Cell Inf o... Stored C ell P artition Cell Id Cell E lemen t Type Cell Z one Type Cell Z one Inde x Overset C ell Type (os) Overset D onor C oun t (os) Overset Rec eptor C oun t (os) Partition N eighb ors X-C oordina te (nv) Mesh... Y-C oordina te (nv) Z-Coordina te (3d , nv) Axial C oordina te (nv) Angular C oordina te (3d , nv) Abs. Angular C oordina te (3d , nv) 2983Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Field Variables List ed b y Categor yVariable Categor y Radial C oordina te Face Area M agnitude X Face Area Y Face Area Z Face Area (3d) Ortho gonal Q ualit y Cell E quiangle S kew Cell E quiv olume S kew Cell Volume 2D C ell Volume (2da) Interface O verlap F raction Cell Wall D istanc e Face Handedness Accumula ted D eformation (dpm, dm, fv) Mark Poor E lemen ts Cell Volume D erivative Cell Volume E rror Dynamic C ell Volume Table 42.13: Mesh Categor y (Turb omachiner y-Specific Variables) Variable Categor y Meridional C oordina te (nv, turb o) Mesh... Abs M eridional C oordina te (nv, turb o) Spanwise C oordina te (nv, turb o) Abs (H-C) S panwise C oordina te (nv, turb o) Abs (C-H) S panwise C oordina te (nv, turb o) Pitchwise C oordina te (nv, turb o) Abs P itchwise C oordina te (nv, turb o) Boundar y Cell D istanc e Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2984Field F unction D efinitionsVariable Categor y Boundar y Normal D istanc e Boundar y Volume D istanc e Cell Refine Table 42.14: Residuals Categor y Variable Categor y Mass Imbalanc e (seg) Residuals ... Pressur e Residual (cpl) X-V elocity Residual (cpl) Y-V elocity Residual (cpl) Z-Velocity Residual (cpl, 3d) Axial-V elocity Residual (cpl, 2da) Radial-V elocity Residual (cpl, 2da) Swirl-Velocity Residual (cpl, 2dasw) Temp erature Residual (cpl, e) Species-n Residual (cpl, sp) Time S tep (cpl) Pressur e Correction (cpl) X-V elocity Correction (cpl) Y-V elocity Correction (cpl) Z-Velocity Correction (cpl, 3d) Axial-V elocity Correction (cpl, 2da) Radial-V elocity Correction (cpl, 2da) Swirl-Velocity Correction (cpl, 2dasw) Temp erature Correction (cpl, e) Species-n Correction (cpl, sp) Table 42.15: Derivatives Categor y Variable Categor y Strain R ate (v) Derivatives... 2985Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Field Variables List ed b y Categor yVariable Categor y dX-V elocity/dx dY-V elocity/dx dZ-V elocity/dx (3d) dAxial-V elocity/dx (2da) dRadial-V elocity/dx (2da) dSwirl-Velocity/dx (2dasw) d sp ecies-n/dx (cpl, sp) dX-V elocity/dy dY-V elocity/dy dZ-V elocity/dy (3d) dAxial-V elocity/dy (2da) dRadial-V elocity/dy (2da) dSwirl-Velocity/dy (2dasw) d sp ecies-n/d y (cpl, sp) dX-V elocity/dz (3d) dY-V elocity/dz (3d) dZ-V elocity/dz (3d) d sp ecies-n/dz (cpl, sp, 3d) dOmega/dx (2dasw) dOmega/d y (2dasw) dp-dX (seg) dp-dY (seg) dp-dZ (seg , 3d) dp-dt (trn) Table 42.16: Potential Categor y Variable Categor y Electric P otential Potential... Current Magnitude Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2986Field F unction D efinitionsVariable Categor y Joule H eat Sour ce Faradaic C urrent Densit y (echem) Total S urface Corrosion R ate (echem) Electrode S urface Potential Faradaic H eat Sour ce (echem) Total E chem H eat Sour ce (echem) Table 42.17: Acoustics Categor y Variable Categor y Surface dp dt RMS (fv, fwh) Acoustics ... Acoustic P ower L evel (dB) (bns) Acoustic P ower (bns) Jet A coustic P ower L evel (dB) (bns , 2da) Jet A coustic P ower (bns , 2da) Surface Acoustic P ower L evel (dB) (bns , fv) Surface Acoustic P ower (bns , fv) Lille y’s Self-N oise S our ce (bns) Lille y’s Shear-N oise S our ce (bns) Lille y’s Total N oise S our ce (bns) LEE S elf-N oise X-S our ce (bns) LEE S hear-N oise X-S our ce (bns) LEE Total N oise X-S our ce (bns) LEE S elf-N oise Y-Sour ce (bns) LEE S hear-N oise Y-Sour ce (bns) LEE Total N oise Y-Sour ce (bns) LEE S elf-N oise Z-S our ce (bns , 3d) LEE S hear-N oise Z-S our ce (bns , 3d) LEE Total N oise Z-S our ce (bns , 3d) Pressur e Spectrum Im n (asff t, 3d) 2987Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Field Variables List ed b y Categor yVariable Categor y Pressur e Spectrum Re n (asff t, 3d) Sound P ressur e (awe) Sound P otential (awe) Sound dP/dt (awe) Sound WaveEq M odel S our ce (awe) Sound WaveEq M odel S our ce Smoothed (awe) Sound WaveEq M odel S our ce M ask (awe) Sound S ponge L ayer M arker (awe) SPL f or O ctave Band a txHz (dB) (asff t, 3d) SPL f or 1/3-O ctave Band a txHz (dB) (asff t, 3d) SPL f or C onst Width B and n(dB) (asff t, 3d) Table 42.18: Structure Categor y Variable Categor y X D isplac emen t (nvs, strc) Structure... Y D isplac emen t (nvs, strc) Z D isplac emen t (nvs, strc, 3d) Sigma X X (str c) Sigma YY (str c) Sigma X Y (str c) Sigma ZZ (str c, 3d) Sigma YZ (str c, 3d) Sigma XZ (str c, 3d) 42.4. Alphab etic al Listing of F ield Variables and Their D efinitions Below, the v ariables list ed in Table 42.1: Pressur e and Densit y Categor ies (p.2966 ) – Table 42.17: Acoustics Categor y (p.2987 ) are defined . For some v ariables (such as r esiduals) a gener al definition is given under the c ategor y name , and v ariables in the c ategor y are not list ed individually .When appr o- priate, the unit quan tity is included , as it app ears in the Quan tities list in the Set U nits D ialog Box (p.3242 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2988Field F unction D efinitionsAbs. Angular C oordina te (in the Mesh... categor y) is the absolut e value of the Angular C oordina te defined ab ove. Abs (C-H) S panwise C oordina te (in the Mesh... categor y) is the dimensional c oordina te in the spanwise dir ection, from c asing t o hub . Its unit quan tity is length . Abs (H-C) S panwise C oordina te (in the Mesh... categor y) is the dimensional c oordina te in the spanwise dir ection, from hub t o casing . Its unit quan tity is length . Abs M eridional C oordina te (in the Mesh... categor y) is the dimensional c oordina te tha t follows the flo w pa th fr om inlet t o outlet. Its unit quan tity is length . Abs P itchwise C oordina te (in the Mesh... categor y) is the dimensional c oordina te in the cir cumf erential (pit chwise) dir ection. Its unit quan tity is angle . Absolut e Pressur e (in the Pressur e... categor y) is equal t o the op erating pr essur e plus the gauge pr essur e. See Operating Pressur e (p.1152 ) for details . Its unit quan tity is pressur e. Absorb ed R adia tion F lux (B and-n) (in the Wall F luxes... categor y) is the amoun t of r adia tive hea t flux absorb ed b y a semi-tr anspar ent wall for a par ticular band of r adia tion. Its unit quan tity is hea t-flux . Absorb ed Visible S olar F lux, Absorb ed IR S olar F lux (in the Wall F luxes... categor y) is the amoun t of solar hea t flux absorb ed b y a semi-tr anspar ent wall or porous jump b oundar y for a visible or infr ared (IR) r adia tion. Absor ption C oefficien t (in the Radia tion... categor y) is the pr operty of a medium tha t descr ibes the amoun t of absor ption of ther mal r adia tion p er unit pa th length within the medium. It can b e interpreted as the in verse of the mean free pa th tha t a phot on will tr avel before being absorb ed (if the absor ption c oefficien t do es not v ary along the pa th).The unit quan tity for Absor ption C oefficien t is length-in verse . Accumula ted D eformation (in the Mesh... categor y) is the accumula ted displac emen t of the w all sur face due t o er osion o ver time .This v ariable will app ear in the Mesh... categor y only f or er osion d ynamic mesh simula tions . See Procedur e for the E rosion C oupled with D ynamic M esh S etup and S olution (p.2002 ) for mor e in- formation. Accum P arcels in C ell (in the Stead y | U nstead y DPM S tatistics ... categor y) •For st eady par ticle tr acking, this is the cumula tive coun t of tr ajec tories tha t has en tered the c ell sinc e the last r eset of the unst eady sta tistics . •For unst eady par ticle tr acking, this is the c oun t of par ticle par cels tha t has en tered the c ell sinc e the last reset of the unst eady sta tistics , wher e each par cel is w eigh ted b y the fr action of the r espective fluid flo w time st ep tha t it ac tually r esides in the c ell. 2989Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Alphab etical Listing of F ield Variables and Their D efinitionsAccum P articles in C ell (in the Stead y | U nstead y DPM S tatistics ... categor y) •For st eady par ticle tr acking, this is the cumula tive sum of tr ajec tories tha t has en tered the c ell sinc e the last r eset of the unst eady sta tistics . Each time a tr ajec tory is c oun ted, the time-c onstan t numb er of particles r epresen ted b y the tr ajec tory in the c ell is added t o the sum. •For unst eady par ticle tr acking, this is the numb er of par ticles in all par cels tha t ha ve en tered the c ell sinc e the last r eset of the unst eady sta tistics . Each par cel is w eigh ted b y the fr action of the r espective fluid flo w time st ep tha t it ac tually r esides in the c ell. Acentric Factor (in the Properties ... categor y) is the mix ture ac entric fac tor.This pr operty is a vailable when a c omp osition dep enden t option is selec ted f or ac entric fac tor in the c ases with A ungier-R edlich-K wong r eal gas mo del and sp ecies tr ansp ort. Acoustic P ower (in the Acoustics ... categor y) is the ac oustic p ower p er unit v olume gener ated b y isotr opic turbulenc e (see Equa tion 15.14 in the Theor y Guide ). It is a vailable only when the Broadband N oise S our ces acoustics mo del is b eing used . Its unit quan tity is power per volume . Acoustic P ower L evel (dB) (in the Acoustics ... categor y) is the ac oustic p ower p er unit v olume gener ated b y isotr opic turbulenc e and r eported in dB (see Equa tion 15.17 in the Theor y Guide ). It is a vailable only when the Broadband Noise S our ces acoustics mo del is b eing used . Active Cell P artition (in the Cell Inf o... categor y) is an in teger iden tifier designa ting the par tition t o which a par ticular c ell b e- longs . In pr oblems in which the mesh is divided in to multiple par titions t o be solv ed on multiple pr ocessors using the par allel v ersion of ANSY S Fluen t, the par tition ID c an b e used t o det ermine the e xtent of the various gr oups of c ells.The ac tive cell par tition is used f or the cur rent calcula tion, while the st ored c ell partition (the last par tition p erformed) is used when y ou sa ve a c ase file . See Partitioning the M esh Manually and B alancing the L oad (p.3071 ) for mor e inf ormation. Adiaba tic F lame Temp erature (in the Premix ed C ombustion... categor y) is the adiaba tic t emp erature of bur nt produc ts in a laminar premix ed flame ( in Equa tion 9.69 in the Theor y Guide ). Its unit quan tity is temp erature. Adjoin t Local S olution M arker (in the Sensitivities ... categor y), intended f or e xpert users who ar e using the Spatial S tabiliza tion Scheme (p.3138 ), can b e plott ed t o iden tify those p ortions of the flo w domain wher e the stabiliz ed adjoin t solution ad vancemen t scheme is applied . It is pr eferable t o plot this with the Node Values disabled in the Contours dialo g box. In this c ase, the Adjoin t Local S olution M arker will tak e a v alue b etween 0 and 1. The Mode A mplitude C utoff defined in the Stabiliz ed Scheme S ettings dialo g box defines the lo wer bound f or cells wher e the stabiliz ed scheme is applied . Angular C oordina te (in the Mesh... categor y) is the angle b etween the r adial v ector and the p osition v ector.The r adial v ector is obtained b y transf orming the default r adial v ector (y-axis) b y the same r otation tha t was applied t o the default axial v ector (z-axis). This assumes tha t, after the tr ansf ormation, the default axial v ector (z-axis) becomes the r eference axis .The angle is p ositiv e in the dir ection of cr oss-pr oduc t between r eference axis and r adial v ector. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2990Field F unction D efinitionsArtificial D issipa tion (in the Sensitivities ... categor y) is a vailable when the adjoin t dissipa tion stabiliza tion scheme is enabled and sho ws the lo cation and amoun t of the nonlinear damping tha t has b een in troduced t o damp the growth of instabilities tha t lead t o adjoin t solution div ergenc e. Average N umb er of P articles in S oot A ggr ega te (In the Soot… categor y) is an a verage numb er of pr imar y par ticles in a so ot aggr egate ( in equa tion Equa tion 14.189 in the Fluent Theor y Guide ).This quan tity is a vailable only with the M etho d of M omen ts model. Axial C oordina te (in the Mesh... categor y) is the distanc e from the or igin in the axial dir ection. The axis or igin and (in 3D) direction is defined f or each c ell z one in the Fluid D ialog Box (p.3457 ) or Solid D ialog Box (p.3467 ).The axial direction f or a 2D mo del is alw ays the direction, and the axial dir ection f or a 2D axisymmetr ic mo del is always the direction. The unit quan tity for Axial C oordina te is length . Axial P ull Velocity (in the Solidific ation/M elting ... categor y) is the axial-dir ection c omp onen t of the pull v elocity for the solid ma terial in a c ontinuous c asting pr ocess. Its unit quan tity is velocity. Axial Velocity (in the Velocity... categor y) is the c omp onen t of v elocity in the axial dir ection. (See Velocity Reporting Options (p.2961 ) for details .) For multiphase mo dels , this v alue c orresponds t o the selec ted phase in the Phase drop-do wn list. Its unit quan tity is velocity. Axial-W all S hear S tress (in the Wall F luxes... categor y) is the axial c omp onen t of the f orce ac ting tangen tial t o the sur face due t o friction. Its unit quan tity is pressur e. Beam Ir radia tion F lux (B and-b) (in the Wall F luxes... categor y) is sp ecified as an inciden t hea t flux ( ) for each w avelength band . Boundar y Cell D istanc e (in the Mesh... categor y) is an in teger tha t indic ates the appr oxima te numb er of c ells fr om a b oundar y zone . Boundar y Normal D istanc e (in the Mesh... categor y) is the distanc e of the c ell c entroid fr om the closest b oundar y zone . Boundar y Volume D istanc e (in the Mesh... categor y) is the c ell v olume distr ibution based on the Boundar y Volume ,Growth F actor, and nor mal distanc e from the selec ted Boundar y Zones defined in the Boundar y (p.2761 ) cell regist er. Capillar y-Pressur e (in the Pressur e... categor y) is the c apillar y pr essur e ac ting on a w etting (sec ondar y) phase in a multiphase flow thr ough a p orous z one . Note tha t, although this it em is a vailable f or b oth non-w etting and w etting phases , meaning ful v alues ar e reported only f or the w etting phase . See Specifying the C apillar y Pres- sure (p.890) for details . Cell C hildr en (in the Adaption... categor y) is a binar y iden tifier based on whether a c ell is the pr oduc t of c ell sub division from the hanging no de adaption pr ocess (v alue = 1) or not (v alue = 0). 2991Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Alphab etical Listing of F ield Variables and Their D efinitionsCell A coustic C our ant Numb er (in the Velocity... categor y) is a r atio of the time st ep siz e to the ac oustic w ave pr opaga tion time based on the c ell siz e. Cell C onvective Cour ant Numb er (in the Velocity... categor y) is a r atio of the time st ep siz e to the c onvective wave pr opaga tion time based on the c ell siz e. Cell E lemen t Type (in the Cell Inf o... categor y) is the in teger c ell elemen t type iden tification numb er. Each c ell c an ha ve one of the f ollowing elemen t types: triangle 1 tetrahedron 2 quadrilateral 3 hexahedron 4 pyramid 5 wedge 6 polyhedra 7 Cell E quiangle S kew (in the Mesh... categor y) is a nondimensional par amet er calcula ted using the nor maliz ed angle de viation metho d, and is defined as (42.1) wher e = lar gest angle in the fac e or c ell = smallest angle in the fac e or c ell = angle f or an equiangular fac e or c ell (f or e xample , 60 f or a tr iangle and 90 f or a squar e) A value of 0 indic ates a b est c ase equiangular c ell, and a v alue of 1 indic ates a c omplet ely degener ate cell. Degener ate cells (sliv ers) ar e char acterized b y no des tha t are near ly coplanar (c ollinear in 2D). Cell E quiangle S kew applies t o all elemen ts. Cell E quiv olume S kew (in the Mesh... categor y) is a nondimensional par amet er calcula ted using the v olume de viation metho d, and is defined as (42.2) wher e optimal-c ell-siz e is the siz e of an equila teral cell with the same cir cumr adius . A v alue of 0 indic ates a b est c ase equila teral cell and a v alue of 1 indic ates a c omplet ely degener ate cell. Degen- erate cells (sliv ers) ar e char acterized b y no des tha t are near ly coplanar (c ollinear in 2D). Cell E qui- volume S kew applies only t o triangular and t etrahedr al elemen ts. Cell Id (in the Cell Inf o... categor y) is a unique in teger iden tifier asso ciated with each c ell. Cell Inf o... includes quan tities tha t iden tify the c ell and its r elationship t o other c ells. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2992Field F unction D efinitionsCell Refine L evel (in the Adaption... categor y) is an in teger tha t indic ates the numb er of times a c ell has b een sub divided by the adaption pr ocess, compar ed with the or iginal mesh. For e xample , if one quad c ell is split in to four quads , the Cell Refine L evel for each of the f our new quads will b e 1. If the r esulting f our quads ar e split again, the Cell Refine L evel for each of the r esulting 16 quads will b e 2. Cell Re ynolds N umb er (in the Velocity... categor y) is the v alue of the R eynolds numb er in a c ell. (Reynolds numb er is a dimen- sionless par amet er tha t is the r atio of iner tia forces to visc ous f orces.) Cell Re ynolds N umb er is defined as (42.3) wher e is densit y, is v elocity magnitude , is the eff ective visc osity (laminar plus turbulen t), and is Cell Volume for 2D c ases and Cell Volume in 3D or axisymmetr ic cases . Cell S urface Area (in the Adaption... categor y) is the t otal sur face area of the c ell, and is c omput ed b y summing the ar ea of the fac es tha t comp ose the c ell. Cell Volume (in the Mesh... categor y) is the v olume of a c ell. In 2D the v olume is the ar ea of the c ell multiplied b y the unit depth. For axisymmetr ic cases , the c ell v olume is c alcula ted using a r eference depth of 1 r adian. The unit quan tity of Cell Volume is volume . Cell Volume D erivative (in the Mesh... categor y) is the change of a c ell v olume o ver time . Cell Volume E rror (in the Mesh... categor y) is the c ell v olume o ver the unst eady cell v olume . 2D C ell Volume (in the Mesh... categor y) is the t wo-dimensional v olume of a c ell in an axisymmetr ic computa tion. For an axisymmetr ic computa tion, the 2D c ell v olume is sc aled b y the r adius . Its unit quan tity is area. Cell Volume C hange (in the Adaption... categor y) is the maximum v olume r atio of the cur rent cell and its neighb ors. Cell Wall D istanc e (in the Mesh... categor y) is the distr ibution of the nor mal distanc e of each c ell c entroid fr om the w all boundar ies. Its unit quan tity is length . Cell Warpage (in the Adaption... categor y) is the squar e root of the r atio of the distanc e between the c ell c entroid and cell cir cumc enter and the cir cumc enter radius: (42.4) Cell Z one Inde x (in the Cell Inf o... categor y) is the in teger c ell z one iden tification numb er. In pr oblems tha t ha ve mor e than one c ell z one , the c ell z one ID c an b e used t o iden tify the v arious gr oups of c ells. 2993Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Alphab etical Listing of F ield Variables and Their D efinitionsCell Z one Type (in the Cell Inf o... categor y) is the in teger c ell z one t ype ID . A fluid c ell has a t ype ID of 1, a solid c ell has a type ID of 17, and an e xterior c ell (par allel solv er) has a t ype ID of 21. Compr essibilit y Factor (in the Properties ... categor y) is the r atio of the ideal gas densit y of the fluid divided b y the r eal gas fluid densit y in the same flo w conditions . Compr essibilit y Factor is defined as (42.5) wher e is the c ompr essibilit y fac tor, is the absolut e pr essur e, is the t emp erature, and (the univ ersal gas c onstan t divided b y the molecular w eigh t ).The c ompr ess- ibilit y fac tor is a vailable only with the r eal gas mo dels . Conc entration of soot species-n (in the Soot... categor y) is the moles p er unit v olume of a so ot sp ecies . Its unit quan tity is c oncentration. (The name of the so ot sp ecies will r eplac e soot species-n in Conc entration of soot species-n .) This quan tity is a vailable only with the M etho d of M omen ts mo del tha t uses the Detailed CHEMKIN Format soot mechanism. Contact Resistivit y (in the Solidific ation/M elting ... categor y) is the additional r esistanc e at the w all due t o contact resistanc e. It is equal t o , wher e is the c ontact resistanc e, is the liquid fr action, and is the c ell heigh t of the w all-adjac ent cell.The unit quan tity for Contact Resistivit y is ther mal-r esistivit y. Critical P ressur e (in the Properties ... categor y) is the mix ture critical pr essur e.This pr operty is a vailable when a c omp osition dep enden t option is selec ted f or cr itical pr essur e in the c ases with A ungier-R edlich-K wong r eal gas mo del and sp ecies tr ansp ort. Critical S pecific Volume (in the Properties ... categor y) is the mix ture critical sp ecific v olume .This pr operty is a vailable when a comp osition dep enden t option is selec ted f or cr itical sp ecific v olume in the c ases with A ungier-R edlich- Kwong r eal gas mo del and sp ecies tr ansp ort. Critical S train R ate (in the Premix ed C ombustion... categor y) is a par amet er tha t tak es in to acc oun t the str etching and e x- tinc tion of pr emix ed flames ( in Equa tion 9.18 in the Theor y Guide ). Its unit quan tity is time-in verse . Critical Temp erature (in the Properties ... categor y) is the mix ture critical temp erature.This pr operty is a vailable when a c om- position dep enden t option is selec ted f or cr itical temp erature in the c ases with A ungier-R edlich-K wong real gas mo del and sp ecies tr ansp ort Current Magnitude (in the Potential... categor y) is the magnitude of the elec tric cur rent vector in the field , . Curvature Correction F unc tion fr (in the Turbulenc e... categor y) is the multiplier of the pr oduc tion t erm when cur vature correction is selec ted for S palar t-Allmar as or t wo equa tion mo dels . See Curvature Correction f or the S palar t-Allmar as and Two- Equa tion M odels in the Fluent Theor y Guide for details . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2994Field F unction D efinitionsCustom F ield F unc tions ... are sc alar field func tions defined b y you.You c an cr eate a cust om func tion using the Custom F ield F unction Calcula tor D ialog Box (p.3797 ). All defined cust om field func tions will b e list ed in the lo wer dr op-do wn list. See Custom F ield F unctions (p.3038 ) for details . Damk ohler N umb er (in the Premix ed C ombustion... categor y) is a nondimensional par amet er tha t is defined as the r atio of turbulen t to chemic al time sc ales . Densit y... includes v ariables r elated t o densit y. Densit y (in the Densit y... categor y) is the mass p er unit v olume of the fluid . Plots or r eports of Densit y include only fluid c ell z ones . For multiphase mo dels , this v alue c orresponds t o the selec ted phase in the Phase drop-do wn list. The unit quan tity for Densit y is densit y. Densit y All (in the Densit y... categor y) is the mass p er unit v olume of the fluid or solid ma terial. Plots or r eports of Densit y All include b oth fluid and solid c ell z ones .The unit quan tity for Densit y All is densit y. Derivatives... are the visc ous der ivatives. For e xample ,dX-V elocity/dx is the first der ivative of the comp onen t of v e- locity with r espect to the -coordina te dir ection. You c an c omput e first der ivatives of v elocity, angular velocity, and pr essur e in the pr essur e-based solv er, and first der ivatives of v elocity, angular v elocity, tem- perature, and sp ecies in the densit y-based solv ers. DES L ength Sc ale (in the Turbulenc e... categor y) is a vailable when y ou k eep the t emp orary solv er memor y from b eing fr eed using the solve/set/expert text command . It is defined b y Equa tion 4.245 in the Theor y Guide for the S palar t-Allmar as based DES mo del and Equa tion 4.252 in the Theor y Guide for the r ealizable k-epsilon based DES mo del. The DES length sc ale f or the BSL / SST k-omega based DES mo del is defined b y , wher e is a c alibr ation c onstan t used in the DES mo del and has a v alue of 0.61 and is the maximum lo cal gr id spacing ( ). DES TKE D issipa tion M ultiplier (in the Turbulenc e... categor y) is either the multiplier func tion for D etached E ddy Simula tion (DES) with BSL, SST , or Transition SST (see DES with the BSL or SST k- ω Model and DES with the Transition SST Model in the Theor y Guide f or details) or the func tion for DES with S palar t-Allmar as or R ealizable - (see Theor y Guide DES with the S palar t-Allmar as M odel or DES with the R ealizable k- ε Model, respectively). Diamet er (in the Properties ... categor y) is the diamet er of par ticles , droplets , or bubbles of the sec ondar y phase selec ted in the Phase drop-do wn list. Its unit quan tity is length . Diffusion C oef. of Sc alar-n (in the User D efined Sc alars ... categor y) is the diffusion c oefficien t for the th user-defined sc alar tr ansp ort equa tion. See the Fluen t Customiza tion M anual for details ab out defining user-defined sc alars . Discr ete Phase S our ces... includes quan tities r elated t o the discr ete phase mo del sour ces. See Modeling D iscrete Phase (p.1911 ) for details ab out this mo del. 2995Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Alphab etical Listing of F ield Variables and Their D efinitionsDiscr ete Phase Variables ... includes non-sour ce quan tities r elated t o the discr ete phase mo del. See Modeling D iscrete Phase (p.1911 ) for details ab out this mo del. DPM A bsor ption C oefficien t (in the Discr ete Phase Variables ... categor y) is the absor ption c oefficien t for discr ete-phase c alcula tions that involve radia tion ( in Equa tion 5.17 in the Theor y Guide ). Its unit quan tity is length-in verse . DPM A ccretion (in the Discr ete Phase Variables ... categor y) is the accr etion r ate calcula ted a t a w all b oundar y: (42.6) wher e is the mass flo w rate of the par ticle str eam, and is the ar ea of the w all fac e wher e the par ticle str ikes the b oundar y.This it em will app ear only if the optional er osion/accr etion mo del is enabled . See Monit oring E rosion/A ccretion of P articles a t Walls (p.1927 ) for details .The unit quan tity for DPM A ccretion is mass-flux . DPM Bur nout (in the Discr ete Phase S our ces... categor y) is the e xchange of mass fr om the discr ete to the c ontinuous phase f or the c ombustion la w (La w 5) and is pr oportional t o the solid phase r eaction r ate.The bur nout exchange has units of mass-flo w and is r eported as the r ate occur ring in each c ell. A unit c ell depth is used f or 2D c ases , and a r eference cell depth of 1 r adian is used f or 2D axisymmetr ic cases . DPM C ollision R ate (in the Discr ete Phase Variables ... categor y) is the time r ate of par ticle-t o-par ticle c ollisions p er unit volume . Its unit quan tity is collision-r ate. DPM C onc entration (in the Discr ete Phase Variables ... categor y) is the t otal c oncentration of the par ticles in all phases in a cell. Its unit quan tity is densit y. DPM C onc of (in the Discr ete Phase Variables ... categor y) is the mean c oncentration of in the par ticles within a c ell, comput ed p er phase .Therefore, when using DDPM, this quan tity app ears f or each c ombina tion of and discr ete par ticle phase (including the mix ture phase). Its unit quan tity is densit y. DPM D ensit y (in the Discr ete Phase Variables ... categor y) is the mean par ticle densit y.This is c omput ed as the mean densit y of the par ticles in each c ell and is c omput ed p er phase .Therefore, when using DDPM this quan tity is available f or each discr ete phase and the mix ture phase . Its unit quan tity is densit y. DPM D iamet er (in the Discr ete Phase Variables ... categor y) is the mean par ticle diamet er.This is c omput ed as the mean diamet er of the discr ete phase par ticles in each c ell and is c omput ed p er phase .Therefore, when using DDPM this quan tity is a vailable f or each discr ete phase and the mix ture phase . Its unit quan tity is length . DPM E mission (in the Discr ete Phase Variables ... categor y) is the amoun t of r adia tion emitt ed b y a discr ete-phase par ticle per unit v olume . Its unit quan tity is hea t-gener ation-r ate. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2996Field F unction D efinitionsDPM E nthalp y Sour ce (in the Discr ete Phase S our ces... categor y) is the e xchange of en thalp y (sensible en thalp y plus hea t of formation) fr om the discr ete phase t o the c ontinuous phase .The e xchange is p ositiv e when the par ticles are a sour ce of hea t in the c ontinuous phase .The unit quan tity for DPM E nthalp y Sour ce is power and is reported as the r ate of e xchange o ccur ring in each c ell. A unit c ell depth is used f or 2D c ases , and a r ef- erence cell depth of 1 r adian is used f or 2D axisymmetr ic cases . DPM E rosion R ate (G ener ic) (in the Discr ete Phase Variables ... categor y) is the er osion r ate calcula ted a t a w all b oundar y fac e using Equa tion 16.324 in the Fluent Theor y Guide based on the v alues en tered in the Gener ic Erosion M odel Paramet ers dialo g box (see Setting P article E rosion and A ccretion P aramet ers (p.1996 )).This it em will app ear only if the Erosion/A ccretion option is selec ted in the Physical M odels tab of the Discrete Phase M odel Dialog Box (p.3360 ) and the Gener ic M odel option is enabled in the DPM tab of the Wall D ialog Box (p.3549 ). See Monit oring E rosion/A ccretion of P articles a t Walls (p.1927 ) for details .The unit quan tity for DPM E rosion Rate (G ener ic) is mass-flux . DPM E rosion R ate (F innie) (in the Discr ete Phase Variables ... categor y) is the F innie er osion r ate calcula ted using the F innie f ormu- lation. (See Accretion in the Fluent Theor y Guide for back ground inf ormation ab out this mo del.) This it em will app ear only if the Finnie option is enabled in the Physical M odels tab of the Discrete Phase M odel Dialog Box (p.3360 ). See Monit oring E rosion/A ccretion of P articles a t Walls (p.1927 ) for details .The unit quan tity for DPM E rosion R ate (F innie) is mass-flux . DPM E rosion R ate (M cLaur y) (in the Discr ete Phase Variables ... categor y) is the M cLaur y erosion r ate calcula ted using the M cLaur y formula tion. (See McLaur y Erosion M odel in the Fluent Theor y Guide for back ground inf ormation ab out this mo del.) This it em will app ear only if the McLaur y erosion mo del is enabled in the Physical M odels tab of the Discrete Phase M odel D ialog Box (p.3360 ). See Monit oring E rosion/A ccretion of P articles a t Walls (p.1927 ) for details .The unit quan tity for DPM E rosion R ate (M cLaur y) is mass-flux . DPM E rosion R ate (O ka) (in the Discr ete Phase Variables ... categor y) is the O ka erosion r ate calcula ted using the O ka formula tion. (See Oka Erosion M odel in the Fluent Theor y Guide for back ground inf ormation ab out this mo del.) This it em will app ear only if the Oka erosion mo del is enabled in the Physical M odels tab of the Discrete Phase Model D ialog Box (p.3360 ). See Monit oring E rosion/A ccretion of P articles a t Walls (p.1927 ) for details .The unit quan tity for DPM E rosion R ate (O ka) is mass-flux . DPM E rosion R ate (Wall S hear) (in the Discr ete Phase Variables ... categor y) is the abr asiv e erosion r ate calcula ted using the shear str ess formula tion. See Modeling E rosion R ates in D ense F lows in the Fluent Theor y Guide for back ground inf orm- ation ab out this mo del. See Monit oring E rosion/A ccretion of P articles a t Walls (p.1927 ) for details .The unit quan tity for DPM E rosion R ate (Wall S hear) is mass-flux .This quan tity is a vailable f or dense flo ws for which DPM er osion is enabled and with the disp erse gr anular sec ondar y phase . DPM E vaporation/D evolatiliza tion (in the Discr ete Phase S our ces... categor y) is the e xchange of mass , due t o dr oplet-par ticle e vaporation or combusting-par ticle de volatiliza tion, from the discr ete phase t o the e vaporating or de volatilizing sp ecies . If you ar e not using the non-pr emix ed c ombustion mo del, the mass sour ce for each individual sp ecies (DPM species-n Sour ce, below) is also a vailable; for non-pr emix ed c ombustion, only this sum is a vailable . The unit quan tity for DPM E vaporation/D evolatiliza tion is mass-flo w and is r eported as the r ate of e x- change o ccur ring in each c ell. A unit c ell depth is used f or 2D c ases , and a r eference cell depth of 1 r adian is used f or 2D axisymmetr ic cases . 2997Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Alphab etical Listing of F ield Variables and Their D efinitionsDPM G ranular Temp erature (in the Discr ete Phase Variables ... categor y) is the mean G ranular Temp erature for the discr ete phase particles within a c ell. Its unit quan tity is turbulen t kinetic ener gy.This quan tity is only a vailable when using a gr anular sec ondar y phase in the D ense D iscrete Phase M odel. DPM M ass S our ce (in the Discr ete Phase S our ces... categor y) is the t otal e xchange of mass fr om the discr ete phase t o the continuous phase .The mass e xchange is p ositiv e when the par ticles ar e a sour ce of mass in the c ontinuous phase . If you ar e not using the non-pr emix ed c ombustion mo del, DPM M ass S our ce will b e equal t o the sum of all sp ecies mass sour ces (DPM species-n Sour ce, below); if you ar e using the non-pr emix ed combustion mo del, it will b e equal t o DPM Bur nout plus DPM E vaporation/D evolatiliza tion .The unit quan tity for DPM M ass S our ce is mass-flo w and is r eported as the r ate of e xchange o ccur ring in each cell. A unit c ell depth is used f or 2D c ases , and a r eference cell depth of 1 r adian is used f or 2D axisymmetr ic cases . DPM D20 (in the Discr ete Phase Variables ... categor y) is the sur face mean diamet er for the discr ete phase par ticles within a c ell.This is c omput ed p er phase .Therefore, when using DDPM this quan tity is a vailable f or each discr ete phase and the mix ture phase . Its unit quan tity is length . For the definition of the D20 diamet er, refer to Summar y Reporting of C urrent Particles (p.2061 ). DPM D30 (in the Discr ete Phase Variables ... categor y) is the v olume mean diamet er for the discr ete phase par ticles within a c ell.This is c omput ed p er phase .Therefore, when using DDPM this quan tity is a vailable f or each discr ete phase and the mix ture phase . Its unit quan tity is length . For the definition of the D30 diamet er, refer to Summar y Reporting of C urrent Particles (p.2061 ). DPM D32 (in the Discr ete Phase Variables ... categor y) is the S auter mean diamet er for the discr ete phase par ticles within a c ell.This is c omput ed p er phase .Therefore, when using DDPM this quan tity is a vailable f or each discr ete phase and the mix ture phase . Its unit quan tity is length . For the definition of the S auter diamet er, refer to Summar y Reporting of C urrent Particles (p.2061 ). DPM D43 (in the Discr ete Phase Variables ... categor y) is the mean diamet er o ver volume (also c alled D e Brouck ere mean diamet er) f or the discr ete phase par ticles within a c ell.This is c omput ed p er phase .Therefore, when using DDPM this quan tity is a vailable f or each discr ete phase and the mix ture phase . Its unit quan tity is length . For the definition of the D e Brouck ere diamet er, refer to Summar y Reporting of C urrent Particles (p.2061 ). DPM N umb er D ensit y (in the Discr ete Phase Variables ... categor y) is the numb er of par ticles p er unit c ell v olume .This is c om- puted p er phase .Therefore, when using DDPM this quan tity is a vailable f or each discr ete phase and the mixture phase . Its unit quan tity is volume-in verse . DPM P arcels in C ell (in the Discr ete Phase Variables ... categor y) •For st eady par ticle tr acking, this is the c oun t of tr ajec tories tha t en tered the c ell dur ing the last DPM it- eration. •For unst eady par ticle tr acking, this is the c oun t of par ticle par cels tha t en tered the c ell dur ing the last DPM it eration. Each par cel is w eigh ted b y the fr action of the fluid flo w time st ep tha t it ac tually r esides in the c ell. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 2998Field F unction D efinitionsThis is c omput ed p er phase .Therefore, when using DDPM this quan tity is a vailable f or each discr ete phase and the mix ture phase . DPM P articles in C ell (in the Discr ete Phase Variables ... categor y) •For st eady par ticle tr acking, this is the time-c onstan t numb er of par ticles tha t is r epresen ted b y all tr a- jectories in the c ell. •For unst eady par ticle tr acking, this is the numb er of par ticles in all par cels tha t en tered the c ell dur ing the last DPM it eration, wher e each par cel is w eigh ted b y the fr action of the fluid flo w time st ep tha t it actually r esides in the c ell. This is c omput ed p er phase .Therefore, when using DDPM this quan tity is a vailable f or each discr ete phase and the mix ture phase . DPM RMS D iamet er (in the Discr ete Phase Variables ... categor y) is the RMS par ticle diamet er.This is c omput ed as the RMS particle diamet er within each c ell and is c omput ed p er phase .Therefore, when using DDPM, this quan tity is available f or each discr ete phase and the mix ture phase . Its unit quan tity is length. DPM RMS Temp erature (in the Discr ete Phase Variables ... categor y) is the RMS par ticle t emp erature.This is c omput ed as the RMS par ticle t emp erature within each c ell and is c omput ed p er phase .Therefore, when using DDPM this quan tity is a vailable f or each discr ete phase and the mix ture phase . Its unit quan tity is temp erature. DPM RMS X, Y, Z Velocity (in the Discr ete Phase Variables ... categor y) ar e the RMS X, Y, and Z Velocity comp onen ts of the discr ete phase .These ar e comput ed as the mean discr ete phase RMS v elocities and ar e comput ed p er phase . Therefore, when using DDPM these quan tities ar e available f or each discr ete phase and the mix ture phase . Its unit quan tity is velocity. DPM Sc attering (in the Discr ete Phase Variables ... categor y) is the sc attering c oefficien t for discr ete-phase c alcula tions that involve radia tion ( in Equa tion 5.17 in the Theor y Guide ). Its unit quan tity is length-in verse . DPM S ensible E nthalp y Sour ce (in the Discr ete Phase S our ces... categor y) is the e xchange of sensible en thalp y from the discr ete phase to the c ontinuous phase .The e xchange is p ositiv e when the par ticles ar e a sour ce of hea t in the c ontinuous phase . Its unit quan tity is power and is r eported as the r ate of e xchange o ccur ring in each c ell. A unit c ell depth is used f or 2D c ases , and a r eference cell depth of 1 r adian is used f or 2D axisymmetr ic cases . DPM species-n Sour ce (in the Discr ete Phase S our ces... categor y) is the e xchange of mass , due t o dr oplet-par ticle e vaporation or combusting-par ticle de volatiliza tion, from the discr ete phase t o the e vaporating or de volatilizing sp ecies . (The name of the sp ecies will r eplac e species-n in DPM species-n Sour ce.) These sp ecies c an b e specified in the Set Injec tion P roperties D ialog Box (p.3917 ), and their descr iptions c an b e found in Defining Injec tion P roperties (p.1969 ).The unit quan tity is mass-flo w and is r eported as the r ate of e xchange o ccur ring in each c ell. A unit c ell depth is used f or 2D c ases , and a r eference cell depth of 1 r adian is used f or 2D axisymmetr ic cases . Note tha t this v ariable will not b e available if y ou ar e using the non-pr emix ed c ombus- tion mo del; use DPM E vaporation/D evolatiliza tion inst ead. 2999Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Alphab etical Listing of F ield Variables and Their D efinitionsDPM S pecific H eat (in the Discr ete Phase Variables ... categor y) is the mean par ticle sp ecific hea t.This is c omput ed as the mean sp ecific hea t of the par ticles within each c ell and is c omput ed p er phase .Therefore, when using DDPM this quan tity is a vailable f or each discr ete phase and the mix ture phase . Its unit quan tity is specific- hea t. DPM S wirl Momen tum S our ce (in the Discr ete Phase S our ces... categor y) is the e xchange of swir l momen tum fr om the discr ete phase to the c ontinuous phase .This v alue is p ositiv e when the par ticles ar e a sour ce of momen tum in the c on- tinuous phase .The unit quan tity is force and is r eported as the r ate of e xchange o ccur ring in each c ell. A unit c ell depth is used f or 2D c ases , and a r eference cell depth of 1 r adian is used f or 2D axisymmetr ic cases . DPM Temp erature (in the Discr ete Phase Variables ... categor y) is the mean par ticle t emp erature.This is c omput ed as the mean t emp erature of the par ticles within each c ell and is c omput ed p er phase .Therefore, when using DDPM this quan tity is a vailable f or each discr ete phase and the mix ture phase . Its unit quan tity is temp er- ature. DPM Volume F raction (in the Discr ete Phase Variables ... categor y) is the v olume fr action of the discr ete phase .This is c omput ed as the mean discr ete phase v olume fr action within each c ell and is c omput ed p er phase .Therefore, when using DDPM this quan tity is a vailable f or each discr ete phase and the mix ture phase . DPM Wall N ormal P ressur e (in the Discr ete Phase Variables ... categor y) is the magnitude of the w all force vector p er unit ar ea. DPM Wall X, Y, Z F orce (in the Discr ete Phase Variables ... categor y) ar e the X, Y, and Z c omp onen ts of the DPM par ticle-w all force.These ar e comput ed on all w all b oundar y conditions . For st eady-sta te simula tions , the r eported forces ar e the mean f orces e xerted b y the par ticles p er unit time . For tr ansien t simula tions , the r eported forces ar e the accumula ted par ticle-w all forces o ver the simula tion time . DPM X, Y, Z M omen tum S our ce (in the Discr ete Phase S our ces... categor y) ar e the e xchange of -, -, and -direction momen tum fr om the discr ete phase t o the c ontinuous phase .These v alues ar e positiv e when the par ticles ar e a sour ce of momen tum in the c ontinuous phase .The unit quan tity is force and is r eported as the r ate of e xchange occur ring in each c ell. A unit c ell depth is used f or 2D c ases , and a r eference cell depth of 1 r adian is used for 2D axisymmetr ic cases . DPM X, Y, Z Velocity (in the Discr ete Phase Variables ... categor y) ar e the X, Y, and Z Velocity comp onen ts of the discr ete phase . These ar e comput ed as the mean discr ete phase v elocities and ar e comput ed p er phase .Therefore, when using DDPM these quan tities ar e available f or each discr ete phase and the mix ture phase . Its unit quan tity is velocity. DRG Reduc ed N umb er of Reac tions (in the Reac tions… categor y) is the numb er of r etained r eactions in r educ ed mechanism. This v ariable quan tifies the siz e of the r educ ed mechanism a t each c ell or par ticle in the domain. DRG Reduc ed N umb er of S pecies (in the Species ... categor y) is the numb er of r etained sp ecies in r educ ed mechanism. This v ariable quan tifies the siz e of the r educ ed mechanism a t each c ell or par ticle in the domain. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3000Field F unction D efinitionsDynamic C ell Volume C hange (in the Mesh... categor y) is the change of a c ell v olume . Dynamic P ressur e (in the Pressur e... categor y) is defined as . Its unit quan tity is pressur e. Echem Reac tion R ate of Reac tion-n (in the Reac tions ... categor y) is the th elec trochemic al reaction r ate.This quan tity is only a vailable if the elec trochemic al reaction mo del is enabled . Eff D iff C oef of species-n (in the Species ... categor y) is the sum of the laminar and turbulen t diffusion c oefficien ts of a sp ecies in to the mix ture: (42.7) (The name of the sp ecies will r eplac e species-n in Eff D iff C oef of species-n .) The unit quan tity is mass-diffusivit y. Effective Prandtl N umb er (in the Turbulenc e... categor y) is the r atio , wher e is the eff ective visc osity, is the specific hea t, and is the eff ective ther mal c onduc tivit y. Effective Thermal C onduc tivit y (in the Properties ... categor y) is the sum of the laminar and turbulen t ther mal c onduc tivities , , of the fluid . A lar ge ther mal c onduc tivit y is asso ciated with a go od hea t conduc tor and a small ther mal c onduc t- ivity with a p oor hea t conduc tor (go od insula tor). Its unit quan tity is ther mal-c onduc tivit y. Effective Visc osit y (in the Turbulenc e... categor y) is the sum of the laminar and turbulen t visc osities of the fluid .Viscosity, , is defined b y the r atio of shear str ess t o the r ate of shear . Its unit quan tity is visc osit y. Electric P otential (in the Potential... categor y) is the elec tric potential used in Equa tion 7.96 in the Fluent Theor y Guide . Electric C onduc tivit y (in the Properties ... categor y) is the elec tric conduc tivit y used in Equa tion 7.84 in the Fluent Theor y Guide . Electrode S urface Potential (in the Potential... categor y) is either the elec trode p otential ( in the B utler-V olmer Equa tion 7.86 in the Fluent Theor y Guide ) for w alls with F aradaic r eaction, or the w all p otential af ter consider ing the c ontact resistanc e eff ect for w alls without F aradaic r eaction. Enthalp y (in the Temp erature... categor y) is defined diff erently for compr essible and inc ompr essible flo ws, and dep ending on the solv er and mo dels in use . For c ompr essible flo ws, (42.8) 3001Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Alphab etical Listing of F ield Variables and Their D efinitionsand f or inc ompr essible flo ws, (42.9) wher e and are, respectively, the mass fr action and en thalp y of sp ecies . (See Enthalp y of species-n , below). For the pr essur e-based solv er, the sec ond t erm on the r ight-hand side of Equa tion 42.9 (p.3002 ) is included only if the pr essur e work term is included in the ener gy equa tion (see Inclusion of P ressur e Work and K inetic Ener gy Terms in the Theor y Guide). For multiphase models , this v alue c orresponds t o the selec ted phase in the Phase drop-do wn list. For all r eacting flow mo dels , the Enthalp y plots c onsist of the ther mal (or sensible) plus chemic al ener gy.The unit quan tity for Enthalp y is specific-ener gy. In the c ase of the iner t mo del ( Using the N on-P remix ed M odel with the Iner t Model in the Theor y Guide ), the en thalp y in a c ell is split in to the c ontributions fr om the iner t and the r eacting fr actions of the gas phase sp ecies in the c ell.The c ell en thalp y is par titioned as (42.10) wher e is the fr action of iner t sp ecies in the c ell.The quan tity is the en thalp y of the iner t species a t the c ell t emp erature, similar ly is the en thalp y of the ac tive sp ecies a t the c ell t em- perature. It is assumed tha t the c ell t emp erature is c ommon t o both iner t and ac tive sp ecies , so , and the c ell t emp erature ar e chosen so tha t Equa tion 42.10 (p.3002 ) is sa tisfied . Enthalp y of species-n (in the Species ... categor y) is defined diff erently dep ending on the solv er and mo dels options in use .The quan tity: (42.11) wher e is the f ormation en thalp y of sp ecies at the r eference temp erature , is reported only f or non-adiaba tic PDF c ases , or if the densit y-based solv er is selec ted.The quan tity: (42.12) wher e , is reported in all other c ases .The unit quan tity for Enthalp y of species- n is specific-ener gy. Entropy (in the Temp erature... categor y) is a ther modynamic pr operty defined b y the equa tion (42.13) (42.14) the en tropy is c omput ed using the equa tion (42.15) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3002Field F unction D efinitionsThe unit quan tity for en tropy is specific-hea t. Imp ortant Note tha t for the r eal gas mo dels the en tropy is c omput ed acc ordingly b y the appr opriate equa tion of sta te formula tion. Existing Value (in the Adaption... categor y) is the v alue tha t presen tly r esides in the t emp orary spac e reser ved f or cell variables (tha t is, the last v alue tha t you displa yed or c omput ed). Face Area M agnitude (in the Mesh... categor y) is the magnitude of the fac e area v ector for nonin ternal fac es (tha t is, faces tha t only ha ve c0 and no c1).The v alues ar e stored on the fac e itself and used when r equir ed.This v ariable is intended only f or zone sur faces and not f or other sur faces cr eated f or p ostpr ocessing . Face Handedness (in the Mesh... categor y) is a par amet er tha t is equal t o one in c ells tha t are adjac ent to lef t-handed fac es, and z ero elsewher e. It can b e used t o locate mesh pr oblems . Faradaic C urrent Densit y (in the Potential... categor y) is the elec tric cur rent densit y pr oduced b y the elec trochemic al reaction a t Faradaic in terfaces (Equa tion 7.93 in the Fluent Theor y Guide ). Faradaic cur rent densit y is p ositiv e if elec tric current flo ws from the elec trode z one t o the elec trolyt e zone , and nega tive if the elec tric cur rent flo ws in the r everse dir ection. Faradaic H eat Sour ce (in the Potential... categor y) is the ener gy sour ce term due t o the elec trochemic al reaction a t Faradaic interfaces (Equa tion 7.98 in the Fluent Theor y Guide ). Film C our ant Numb er (in the Euler ian Wall F ilm... categor y) is the C ourant numb er of the w all film. Film C overage (in the Euler ian Wall F ilm... categor y) is the v alue of film w et ar ea fr action as defined in Equa tion 22.30 in the Fluent Theor y Guide .In reporting , the fac e integral of this v ariable giv es the ar ea c overed b y the film. This it em is a vailable when Solve M omen tum is enabled in the Euler ian Wall F ilm dialo g box. Film DPM E nergy Sour ce (in the Euler ian Wall F ilm... categor y) is the additional ener gy of discr ete par ticles b eing absorb ed in to the w all film. Film DPM M ass S our ce (in the Euler ian Wall F ilm... categor y) is the additional mass of discr ete par ticles b eing absorb ed in to the wall film. Film DPM X-M omen tum S our ce (in the Euler ian Wall F ilm... categor y) is the x-c omp onen t of an y additional momen tum of discr ete par ticles being absorb ed in to the w all film. Film DPM Y-M omen tum S our ce (in the Euler ian Wall F ilm... categor y) is the y-c omp onen t of an y additional momen tum of discr ete par ticles being absorb ed in to the w all film. 3003Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Alphab etical Listing of F ield Variables and Their D efinitionsFilm DPM Z-M omen tum S our ce (in the Euler ian Wall F ilm... categor y) is the z-c omp onen t of an y additional momen tum of discr ete par ticles being absorb ed in to the w all film. Film E ffective Pressur e (in the Euler ian Wall F ilm... categor y) is the eff ective pr essur e of the w all film. Film M ass (in the Euler ian Wall F ilm... categor y) is the mass of the w all film. Film Outflo w M ass (in the Euler ian Wall F ilm... categor y) is the cumula tive mass of film outflo w. Film P assiv e Sc alar (in the Euler ian Wall F ilm... categor y) is the passiv e sc alar f or the w all film sc alar equa tion. Film P hase C hange R ate (in the Euler ian Wall F ilm... categor y) is the phase change r ate, with p ositiv e value as the c ondensa tion rate and nega tive value as the v aporization r ate.This it em is a vailable when Phase C hange is enabled . Film S econdar y Phase C ollec tion C oef (in the Euler ian Wall F ilm... categor y) is the c oefficien t of sec ondar y phase c ollec tion. This it em is a vailable when Phase A ccretion is enabled . Film S econdar y Phase M ass (in the Euler ian Wall F ilm... categor y) is the mass of sec ondar y phase c ollec tion. This it em is a vailable when Phase A ccretion is enabled . Film S epar ated D iam (in the Euler ian Wall F ilm... categor y) is the diamet er of separ ated w all film dr oplet. This it em is a vailable when Edge S epar ation is enabled . Film S epar ation R ate (in the Euler ian Wall F ilm... categor y) is the mass of sec ondar y phase c ollec tion. This it em is a vailable when Edge S epar ation is enabled . Film S tripped D iam (in the Euler ian Wall F ilm... categor y) is the diamet er of str ipped w all film dr oplets . Film S tripped M ass (in the Euler ian Wall F ilm... categor y) is the cumula tive mass of str ipped w all film. Film S urface Temp erature (in the Euler ian Wall F ilm... categor y) is the sur face temp erature of the w all film. Film S urface Velocity M agnitude (in the Euler ian Wall F ilm... categor y) is the magnitude of the sur face velocity of the w all film. Film S urface X-V elocity (in the Euler ian Wall F ilm... categor y) is the x-c omp onen t of the sur face velocity of the w all film. Film S urface Y-V elocity (in the Euler ian Wall F ilm... categor y) is the y-c omp onen t of the sur face velocity of the w all film. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3004Field F unction D efinitionsFilm S urface Z-V elocity (in the Euler ian Wall F ilm... categor y) is the z-c omp onen t of the sur face velocity of the w all film. Film Temp erature (in the Euler ian Wall F ilm... categor y) is the t emp erature of the w all film. Film Thick ness (in the Euler ian Wall F ilm... categor y) is the thick ness of the w all film. Film Velocity M agnitude (in the Euler ian Wall F ilm... categor y) is the magnitude of the v elocity of the w all film. Film Weber N umb er (in the Euler ian Wall F ilm... categor y) is the Weber numb er of the w all film. Film X-M omen tum S our ce (in the Euler ian Wall F ilm... categor y) is the x-c omp onen t of an y additional momen tum b eing absorb ed into the w all film. Film Y-M omen tum S our ce (in the Euler ian Wall F ilm... categor y) is the y-c omp onen t of an y additional momen tum b eing absorb ed into the w all film. Film X-V elocity (in the Euler ian Wall F ilm... categor y) is the x-c omp onen t of the v elocity of the w all film. Film Y-V elocity (in the Euler ian Wall F ilm... categor y) is the y-c omp onen t of the v elocity of the w all film. Film Z-V elocity (in the Euler ian Wall F ilm... categor y) is the z-c omp onen t of the v elocity of the w all film. Fine Sc ale M ass F raction of species-n (in the Species ... categor y) is the t erm in Equa tion 7.30 in the Theor y Guide . Fine Sc ale Temp erature (in the Temp erature... categor y) is the t emp erature of the fine sc ales , which is c alcula ted fr om the en thalp y when the r eaction pr oceeds o ver the time sc ale ( in Equa tion 7.29 in the Theor y Guide ), governed b y the K inetic r ates of Equa tion 7.7 in the Theor y Guide . Its unit quan tity is temp erature. Fine Sc ale Transf er R ate (in the Species ... categor y) is the tr ansf er rate of the fine sc ales , which is equal t o the in verse of the time scale ( in Equa tion 7.29 in the Theor y Guide ). Its unit quan tity is time-in verse . 1-Fine Sc ale Volume F raction (in the Species ... categor y) is a func tion of the fine sc ale v olume fr action ( in Equa tion 7.28 in the Theor y Guide ).The quan tity is subtr acted fr om unit y to mak e it easier t o interpret. Film S epar ated M ass (in the Euler ian Wall F ilm... categor y) is the cumula tive mass of separ ated w all film. 3005Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Alphab etical Listing of F ield Variables and Their D efinitionsForward Reac tion R ate of PDF scalar-n (in the Premix ed C ombustion... categor y) is the r ate of pr oduc tion of species-n due t o forward reactions for sc alar in k g/m3/s ( in Equa tion 10.16 in the Fluent Theor y Guide ). (The name of the PDF sc alar will r eplac e PDF scalar-n in Forward Reac tion R ate of PDF scalar-n .) Fvar P rod (in the Pdf... categor y) is the pr oduc tion t erm in the mix ture fraction v arianc e equa tion solv ed in the non- premix ed c ombustion mo del (tha t is, the last t wo terms in Equa tion 8.5 in the Theor y Guide ). Fvar2 P rod (in the Pdf... categor y) is the pr oduc tion t erm in the sec ondar y mix ture fraction v arianc e equa tion solv ed in the non-pr emix ed c ombustion mo del. See Equa tion 8.5 in the Theor y Guide . Gas C onstan t (R) (in the Properties ... categor y) is the gas c onstan t of the fluid . Its unit quan tity is specific-hea t. Geometr ic Roughness H eigh t (in the Turbulenc e... categor y) is used in the r oughness c orrelation of the Transition SST mo del. See Equa tion 4.189 in the Theor y Guide . Granular C onduc tivit y (in the Properties ... categor y) is equiv alen t to the diffusion c oefficien t in Equa tion 18.336 in the Theor y Guide . For mor e inf ormation, see Granular Temp erature in the Theor y Guide . Its unit quan tity is k g/m-s . Granular P ressur e... includes quan tities f or reporting the solids pr essur e for each gr anular phase ( in Equa tion 18.307 in the Theor y Guide ). See Solids P ressur e in the Theor y Guide for details . Its unit quan tity is pressur e. For mul- tiphase mo dels , this v alue c orresponds t o the selec ted phase in the Phase drop-do wn list. Granular Temp erature... includes quan tities f or reporting the gr anular t emp erature for each gr anular phase ( in Equa tion 18.336 in the Theor y Guide ). See Granular Temp erature in the Theor y Guide for details . Its unit quan tity is . For multiphase mo dels , this v alue c orresponds t o the selec ted phase in the Phase drop-do wn list. HCN D ensit y (in the NOx... categor y) is the mass p er unit v olume of HCN. The unit quan tity is densit y.The HCN D ensit y will app ear only if y ou ar e mo deling fuel NO x. See Fuel NO x Formation in the Theor y Guide for details . Heat of H eterogeneous Reac tion (in the Phase In teraction... categor y) is the hea t added or r emo ved due t o het erogeneous chemic al reac- tions . For e xother mic r eactions the Heat of H eterogeneous Reac tion is reported as a p ositiv e quan tity, while f or endother mic r eactions it will b e a nega tive quan tity. If you ha ve mor e than one het erogeneous reaction defined in y our c ase, the Heat of H eterogeneous Reac tion reported is the sum of the hea t for all het erogeneous r eactions .The unit quan tity of Heat of H eterogeneous Reac tion is Watt. Heat of Reac tion (in the Reac tions ... categor y) is the hea t added or r emo ved due t o chemic al reactions .The quan tity reported by Fluen t is the v olumetr ic hea t of r eaction, as defined in Equa tion 5.10 in the Theor y Guide multiplied by the c ell v olume . For e xother mic r eactions , the hea t of r eaction is r eported as a p ositiv e quan tity, while for endother mic r eactions it is r eported as a nega tive quan tity. If you ha ve mor e than one r eaction defined in your c ase, the Heat of Reac tion reported is the sum of the hea t for all r eactions .The unit of measur emen t for the hea t of r eaction is Watts.The Heat of Reac tion is not a vailable f or the non-pr emix ed and par tially- premix ed mo dels . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3006Field F unction D efinitionsHeat Release R ate (in the Pdf... categor y) is the r ate of hea t gener ated due t o chemic al reaction ( J/m3/s) as defined in Equa- tion 5.10 in the Fluent Theor y Guide . Helicit y (in the Velocity... categor y) is defined b y the dot pr oduc t of v orticit y and the v elocity vector. (42.16) Vorticit y is a measur e of the r otation of a fluid elemen t as it mo ves in the flo w field . Inciden t Radia tion (in the Radia tion... categor y) is the t otal r adia tion ener gy, , tha t arrives a t a lo cation p er unit time and per unit ar ea: (42.17) wher e is the r adia tion in tensit y and is the solid angle . is the quan tity tha t the P-1 r adia tion model c omput es. For the DO r adia tion mo del, the inciden t radia tion is c omput ed o ver a finit e numb er of discr ete solid angles , each asso ciated with a v ector dir ection. For the MC mo del, the r a- diation in tensit y is c omput ed b y tallying the distanc e travelled b y phot ons in each c ell.The unit quan tity for Inciden t Radia tion is hea t-flux . Inciden t Radia tion (B and n) (in the Radia tion... categor y) is the r adia tion ener gy contained in the w avelength band for the non- gray P-1, DO, or MC r adia tion mo dels . Its unit quan tity is hea t-flux . Interface Overlap F raction (in the Mesh... categor y) is a metr ic for measur ing the qualit y of the in tersec tion b etween in terface zones for non-c onformal in terfaces. It is c alcula ted on each elemen t of the in terface zone and r anges fr om 0 t o 1, wher e 0 means no in tersec tion, and 1 means full in tersec tion. Intermitt enc y (in the Turbulenc e... categor y) is a measur e of the pr obabilit y tha t a giv en p oint is lo cated inside a turbulen t region. Upstr eam of tr ansition the in termitt ency is z ero. Onc e the tr ansition o ccurs , the in termitt ency is ramp ed up t o one un til the fully turbulen t boundar y layer regime is achie ved. Intermitt enc y Effective (in the Turbulenc e... categor y) is used in the c oupling of the Transition mo del and the SST Transp ort equa tions (see Coupling the Transition M odel and SST Transp ort Equa tions in the Theor y Guide f or details). Internal E nergy (in the Temp erature... categor y) is the summa tion of the k inetic and p otential ener gies of the molecules of the substanc e per unit v olume (and e xcludes chemic al and nuclear ener gies). Internal E nergy is defined as . Its unit quan tity is specific-ener gy. Jet A coustic P ower (in the Acoustics ... categor y) is the ac oustic p ower for turbulen t axisymmetr ic jets (see Equa tion 15.18 in the Theor y Guide ). It is a vailable only when the Broadband N oise S our ces acoustics mo del is b eing used . Jet A coustic P ower L evel (dB) (in the Acoustics ... categor y) is the ac oustic p ower for turbulen t axisymmetr ic jets , reported in dB (see Equa tion 15.31 in the Theor y Guide ). It is a vailable only when the Broadband N oise S our ces acoustics model is b eing used . 3007Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Alphab etical Listing of F ield Variables and Their D efinitionsJoule H eat Sour ce (in the Potential... categor y) is the ener gy sour ce term due t o the J oule hea ting ( Equa tion 23.2 in the Fluent Theor y Guide ). Kinetic R ate of Reac tion-n (in the Reac tions ... categor y) is giv en b y the f ollowing e xpression (see Equa tion 7.7 in the Theor y Guide for definitions of the v ariables sho wn her e): (42.18) The r eported v alue is indep enden t of an y par ticular sp ecies , and has units of k mol/ -s. To find the r ate of pr oduc tion/destr uction f or a giv en sp ecies due t o reaction , multiply the r e- ported r eaction r ate for reaction by the t erm , wher e is the molecular w eigh t of species , and and are the st oichiometr ic coefficien ts of sp ecies in r eaction . For par ticle r eactions it is the global r ate of the par ticle r eaction n e xpressed in k mol/s/m3. This is comput ed as wher e is the r ate of par ticle sp ecies depletion (or gener ation) giv en b y Equa tion 7.73 in the Theor y Guide , is the par ticle sp ecies molecular w eigh t, and is the c ell v olume . Lamb da 2 C riterion (in the Turbulenc e... categor y) is a p ostpr ocessing quan tity used f or visual insp ection of turbulenc e structures. Lam D iff C oef of species-n (in the Species ... categor y) is the laminar diffusion c oefficien t of a sp ecies in to the mix ture, . Its unit quan tity is mass-diffusivit y. Laminar F lame S peed (in the Premix ed C ombustion... categor y) is the pr opaga tion sp eed of laminar pr emix ed flames ( in Equa tion 9.8 in the Theor y Guide ). Its unit quan tity is velocity. Laminar K inetic E nergy (k l) (in the Turbulenc e...categor y) is a measur e of the “laminar ” streamwise fluc tuations pr esen t in the pr e- transitional r egion of the b oundar y layer subjec ted t o free-str eam turbulenc e. A tr ansp ort equa tion of k l is consider ed b y the k-k l-omega tr ansition mo del. Latent Heat n (in the Phase In teraction... categor y) is the la tent hea t for the nth mass tr ansf er mechanism tha t you defined . LEE S elf-N oise X-S our ce, LEE S elf-N oise Y-Sour ce, LEE S elf-N oise Z-S our ce (in the Acoustics ... categor y) ar e the self-noise sour ce terms in the linear ized E uler equa tion f or the acoustic v elocity comp onen t (see Equa tion 15.36 in the Theor y Guide ).They are available only when the Broadband N oise S our ces acoustics mo del is b eing used . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3008Field F unction D efinitionsLEE S hear-N oise X-S our ce, LEE S hear-N oise Y-Sour ce, LEE S hear-N oise Z-S our ce (in the Acoustics ... categor y) ar e the shear-noise sour ce terms in the linear ized E uler equa tion f or the acoustic v elocity comp onen t (see Equa tion 15.36 in the Theor y Guide ).They are available only when the Broadband N oise S our ces acoustics mo del is b eing used . LEE Total N oise X-S our ce, LEE Total N oise Y-Sour ce, LEE Total N oise Z-S our ce (in the Acoustics ... categor y) ar e the t otal noise sour ce terms in the linear ized E uler equa tion f or the acoustic v elocity comp onen t (see Equa tion 15.36 in the Theor y Guide ).The t otal noise sour ce term is the sum of the self-noise and shear-noise sour ce terms.They are available only when the Broadband N oise Sour ces acoustics mo del is b eing used . LES S ubgrid Turbulen t Visc osit y (in the Turbulenc e... categor y) is the edd y visc osity tha t is det ermined b y the lo cal algebr aic sub-gr id scale mo del in an emb edded LES z one , which ac tually aff ects the momen tum tr ansp ort equa tions (see Emb edded Lar ge E ddy Simula tion (ELES) in the Theor y Guide ). Its unit quan tity is visc osit y. Lille y’s Self-N oise S our ce (in the Acoustics ... categor y) is the self-noise sour ce term in the linear ized Lille y’s equa tion (see Equa- tion 15.40 in the Theor y Guide ), available only when the Broadband N oise S our ces acoustics mo del is being used . Lille y’s Shear-N oise S our ce (in the Acoustics ... categor y) is the shear-noise sour ce term in the linear ized Lille y’s equa tion (see Equa- tion 15.40 in the Theor y Guide ), available only when the Broadband N oise S our ces acoustics mo del is being used . Lille y’s Total N oise S our ce (in the Acoustics ... categor y) is the t otal noise sour ce term in the linear ized Lille y’s equa tion (see Equa- tion 15.40 in the Theor y Guide ).The t otal noise sour ce term is the sum of the self-noise and shear-noise sour ce terms, available only when the Broadband N oise S our ces acoustics mo del is b eing used . Liquid F raction (in the Solidific ation/M elting ... categor y) is the liquid fr action comput ed b y the solidific ation/melting model: (42.19) (42.20) (42.21) log10(S hap e Sensitivit y M agnitude) (in the Sensitivities ... categor y) pr ovides a c onvenienc e func tion tha t plots of the magnitude , in view of the lar ge r ange of v alues p ossible f or the shap e sensitivit y magnitude .This allo ws the imp ortanc e of the sur faces in a domain t o be ranked mor e easily based on ho w the y aff ect the obser vation of in terest when the y are reshap ed. Lump A sph. by Or tho gonalit y (in the Lump D etection... categor y) is a measur e of the non-spher icity of the liquid lump acc ording t o the surface-radius or thogonalit y metho d. 3009Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Alphab etical Listing of F ield Variables and Their D efinitionsLump A sph. by Rad. Std. Dev. (in the Lump D etection... categor y) is a measur e of the non-spher icity of the liquid lump acc ording t o the radius standar d de viation metho d. Lump D ensit y (in the Lump D etection... categor y) is a v olume-w eigh ted a verage of the lump densit y. Lump D iamet er (in the Lump D etection... categor y) is the diamet er of a v olume-equiv alen t spher e. Lump E nthalp y (in the Lump D etection... categor y) is the a verage sp ecific en thalp y of the lump .This quan tity is a vailable only when the ener gy equa tion is enabled . Lump ID (in the Lump D etection... categor y) is a unique in teger v alue f or e very contiguous p ortion of liquid . One ID is assigned t o the liquid c ore, and other IDs ar e assigned t o each detached lump . Lump P ressur e (in the Lump D etection... categor y) is the a verage pr essur e of the lump .This quan tity is a vailable only when the ener gy equa tion is enabled . Lump Temp erature (in the Lump D etection... categor y) is the a verage t emp erature of the lump .This quan tity is a vailable only when the ener gy equa tion is enabled . Lump X, Y, Z C oordina te (in the Lump D etection... categor y) ar e the X, Y, and Z c oordina tes of the c enter of gr avity of the liquid lump . Lump X, Y, Z Velocity (in the Lump D etection... categor y) ar e the X, Y, and Z c omp onen ts of the liquid lump v elocity vector. Mach N umb er (in the Velocity... categor y) is the r atio of v elocity and sp eed of sound . Magnitude of S ensitivit y to Body Forces (C ell Values) (in the Sensitivities ... categor y) is the magnitude of the adjoin t velocity pr imitiv e field .This field c an b e interpreted as the magnitude of the sensitivit y of the obser vable t o body force per unit v olume . It can b e used t o iden tify r egions in the domain wher e small changes t o the momen tum balanc e in the flo w can have a lar ge or small eff ect on the obser vable .This field is of ten obser ved t o be lar ge, for e xample , upstr eam of a b ody for which dr ag sensitivit y is of in terest, with the field diminishing in the upstr eam dir ection. This indic ates the in terference eff ect for an objec t positioned a t various lo cations upstr eam of the objec t of interest. Mark Poor E lemen ts (in the Mesh... categor y) is a par amet er tha t is equal t o one in c ells tha t are iden tified as in valid or p oor, as w ell as c ells tha t are adjac ent to the fac e of an in valid or p oor cell, and z ero elsewher e. It can b e used to mar k and/or displa y invalid and p oor elemen ts. Mass fr action of HCN, Mass fr action of NH3, Mass fr action of NO , Mass fr action of N2O (in the NOx... categor y) ar e the mass of HCN, the mass of , the mass of NO , and the mass of N2O per unit mass of the mix ture (for e xample , kg of HCN in 1 k g of the mix ture).The Mass fr action of HCN and Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3010Field F unction D efinitionsthe Mass fr action of NH3 will app ear only if y ou ar e mo deling fuel NO x. See Fuel NO x Formation in the Theor y Guide for details . Mass fr action of nuclei (in the Soot... categor y) is the numb er of par ticles p er unit mass of the mix ture (in units of par ticles /kg) The Mass fr action of nuclei will app ear only if y ou use the t wo-st ep so ot mo del. See Soot Formation (p.1854 ) for details . Mass fr action of so ot (in the Soot... categor y) is the mass of so ot p er unit mass of the mix ture (for e xample , kg of so ot in 1 k g of the mix ture). See Soot F ormation (p.1854 ) for details . Mass fr action of species-n (in the Species ... categor y) is the mass of a sp ecies p er unit mass of the mix ture (for e xample , kg of sp ecies in 1 k g of the mix ture). Mass Transf er R ate n (in the Phase In teraction... categor y) is the mass tr ansf er rate for the nth mass tr ansf er mechanism tha t you defined . Mean n (in the Stead y Statistics ... or Unstead y Statistics ... categor y) is the it eration- or time-a veraged v alue of a solution v ariable n (for e xample ,Static P ressur e). See Performing S teady-State Calcula tions (p.2614 ) and Postpr ocessing f or Time-D ependen t Problems (p.2645 ) for details . Mean- cff_n (in the Stead y Statistics ... or Unstead y Statistics ... categor y) is the it eration- or time-a veraged v alue of a cust om field func tion cff_n (for e xample ,uns-cust om-func tion-0 ). See Performing S teady-State Calcula- tions (p.2614 ) and Postpr ocessing f or Time-D ependen t Problems (p.2645 ) for details . Mean DPM n (in the Stead y Statistics ... or Unstead y Statistics ... categor y) is the it eration- or time-a veraged v alue of a discr ete phase v ariable n (for e xample ,Volume F raction ). See Performing S teady-State Calcula tions (p.2614 ) and Postpr ocessing f or Time-D ependen t Problems (p.2645 ) for details . Meridional C oordina te (in the Mesh... categor y) is the nor maliz ed (dimensionless) c oordina te tha t follows the flo w pa th fr om inlet to outlet. Its value v aries fr om to . Mesh... includes v ariables r elated t o the mesh. Mesh X-V elocity, Mesh Y-V elocity, Mesh Z-V elocity (in the Velocity... categor y) ar e the v ector comp onen ts of the mesh v elocity for mo ving-mesh pr oblems (rotating or multiple r eference frames , mixing planes , or sliding meshes). Its unit quan tity is velocity. Mixture Fraction Varianc e (in the Pdf... categor y) is the v arianc e of the mix ture fraction solv ed f or in the non-pr emix ed c ombustion model. This is the sec ond c onser vation equa tion (along with the mix ture fraction equa tion) tha t the non- premix ed c ombustion mo del solv es. (See Definition of the M ixture Fraction in the Theor y Guide .) Modified Turbulen t Visc osit y (in the Turbulenc e... categor y) is the tr ansp orted quan tity tha t is solv ed f or in the S palar t-Allmar as tur- bulenc e mo del and in DES with the S palar t-Allmar as mo del (see Equa tion 4.15 in the Theor y Guide ).The 3011Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Alphab etical Listing of F ield Variables and Their D efinitionsturbulen t visc osity, , is comput ed dir ectly fr om this quan tity using the r elationship giv en b y Equa tion 4.16 in the Theor y Guide . Its unit quan tity is visc osit y. Molar C onc entration of species-n (in the Species ... categor y) is the moles p er unit v olume of a sp ecies . Its unit quan tity is conc entration . Mole fr action of species-n (in the Species ... categor y) is the numb er of moles of a sp ecies in one mole of the mix ture. Mole fr action of HCN, Mole fr action of NH3, Mole fr action of NO , Mole fr action of N2O (in the NOx... categor y) ar e the numb er of moles of HCN, , NO, and N2O in one mole of the mix ture. The Mole fr action of HCN and the Mole fr action of NH3 will app ear only if y ou ar e mo deling fuel NO x. See Fuel NO x Formation in the Theor y Guide for details . Mole fr action of so ot (in the Soot... categor y) is the numb er of moles of so ot in one mole of the mix ture. Molecular P randtl N umb er (in the Properties ... categor y) is the r atio . Molecular Visc osit y (in the Properties ... categor y) is the laminar visc osity of the fluid .Viscosity, , is defined b y the r atio of shear str ess t o the r ate of shear . Its unit quan tity is visc osit y. For multiphase mo dels , this v alue c orresponds to the selec ted phase in the Phase drop-do wn list. For a gr anular phase , the molecular visc osity is multiplied by the gr anular v olume fr action. Momen tum Thick ness Re ( ) (in the Turbulenc e... categor y) is based on the momen tum thick ness of the b oundar y layer.The SST transition mo del is c onsider ing a nonlo cal empir ical correlation f or the v alue of in the fr ee-str eam, based on turbulenc e intensit y, pressur e gr adien t, and so on, and a tr ansp ort equa tion t o allo w the fr ee- stream v alue t o diffuse in to the b oundar y layer. NH3 D ensit y, NO D ensit y, N2O D ensit y (in the NOx... categor y) ar e the mass p er unit v olume of NH3, NO, and N2O.The unit quan tity for each is densit y.The NH3 D ensit y will app ear only if y ou ar e mo deling fuel NO x. See Fuel NO x Formation in the Theor y Guide for details . Non-E quilibr ium Thermal M odel S our ce (in the Temp erature... categor y) is the sc aled v alue of ther mal c onduc tivit y for the fluid z one ( ) or f or the o verlapping solid z one ( ), wher e is the p orosity, is the fluid phase ther mal c onduc tivit y (including the turbulen t contribution, ), and is the solid medium ther mal c onduc tivit y.These t erms can b e seen in Equa tion 7.14 (p.868) and Equa tion 7.15 (p.868). See Non-E quilibr ium Thermal M odel E qua tions (p.868) and Non-E quilibr ium Thermal M odel (p.884) for details ab out the non-equilibr ium ther mal mo del. Normal Optimal D isplac emen t (in the Sensitivities ... categor y) sho ws the nor mal c omp onen t of the optimal displac emen t comput ed from the adjoin t solution. This field is defined only f or p ortions of w alls lying within the c ontrol-volume specified f or mor phing .The siz e of the optimal displac emen t is det ermined b y the sc ale fac tor tha t is chosen f or the mor phing . A p ositiv e value of displac emen t indic ates tha t the sur face will b e displac ed in to the flo w domain, wher eas a nega tive value of displac emen t corresponds t o wall mo vemen t out wards fr om Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3012Field F unction D efinitionsthe flo w domain. This field elimina tes the c omp onen t of the optimal displac emen t vector tha t lies in the plane of the w all. Normal S hap e Sensitivit y (in the Sensitivities ... categor y) sho ws the nor mal c omp onen t of the shap e sensitivit y. A p ositiv e value indic ates an or ientation dir ected in to the domain, while a nega tive value indic ates tha t the shap e sensitivit y is or iented out wards fr om the domain. This field elimina tes the c omp onen t of the v ector shap e sensitivit y field tha t lies in the plane of the w all. Normaliz ed C onc entration of N uclei (in the Soot... categor y) is the nor maliz ed so ot par ticle numb er densit y. Normaliz ed Q C riterion (in the Turbulenc e... categor y) is a p ostpr ocessing quan tity used f or visual insp ection of turbulenc e structures. Normaliz ed S oot A ggr ega tion M omen ts (in the Soot... categor y) is the nor maliz ed so ot aggr egate momen ts.This quan tity is a vailable only with the M etho d of M omen ts mo del. Normaliz ed so ot momen ts (in the Soot... categor y) ar e the nor maliz ed so ot momen ts.This quan tity is a vailable only with the M etho d of M omen ts mo del. NOx... contains quan tities r elated t o the NO x mo del. See NOx Formation (p.1823 ) for details ab out this mo del. Ortho gonal Q ualit y (in the Mesh... categor y) is a measur e of the qualit y of a mesh, and is c omput ed f or each c ell using the vectors fr om the c ell c entroid t o each of its fac es, the ar ea v ectors of the c ell's fac es, and the v ectors fr om the c ell c entroid t o the c entroids of each of the adjac ent cells (see Equa tion 6.1 (p.719) and Equa- tion 6.2 (p.719)).The w orst c ells will ha ve an Ortho gonal Q ualit y closer t o 0, with b etter cells closer t o 1. Overset C ell Type (in the Cell Inf o... categor y) is an in teger v alue indic ating the o verset c ell type. Each c ell c an ha ve one of the f ollowing v alues: Integer F unc tion ValueCell Type 2 donor 1 solv e 0 receptor –1 orphan –2 dead Overset D onor C oun t (in the Cell Inf o... categor y) sho ws the numb er of donor c ells a r eceptor cell has f or da ta in terpolation. A value of z ero indic ates tha t the c ell is not a r eceptor, or tha t the r eceptor cell is an or phan c ell. Overset Rec eptor C oun t (in the Cell Inf o... categor y) sho ws the numb er of r eceptor cells r eferencing a donor c ell. A value of z ero indic ates tha t the c ell is not a donor c ell. 3013Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Alphab etical Listing of F ield Variables and Their D efinitionsPrimar y Particle D iamet er (in the Soot... categor y) is a so ot pr imar y par ticle diamet er within so ot aggr egates.This quan tity is a vailable only with the M etho d of M omen ts mo del. Partition B oundar y Cell D istanc e (in the Mesh... categor y) is the smallest numb er of c ells tha t must b e traversed t o reach the near est par tition (interface) b oundar y. Partition N eighb ors (in the Cell Inf o... categor y) is the numb er of adjac ent par titions (tha t is, those tha t shar e at least one partition b oundar y fac e (in terface)). It giv es a measur e of the numb er of messages tha t will ha ve to be gener ated f or par allel pr ocessing . Pdf... contains quan tities r elated t o the non-pr emix ed c ombustion mo del, which is descr ibed in Modeling N on- Premix ed C ombustion (p.1687 ). PDF Table A diaba tic E nthalp y is the adiaba tic en thalp y corresponding t o the c ell v alue of mix ture fraction. For single mix ture fraction cases it is giv en b y the f ollowing equa tion: (42.22) and f or c ases in volving a sec ondar y str eam it is giv en b y the f ollowing equa tion: (42.23) wher e = mix ture fraction = sec ondar y mix ture fraction = total en thalp y of the fuel str eam = total en thalp y of the sec ondar y str eam = total en thalp y of the o xidiz er str eam For adiaba tic c ases the PDF Table A diaba tic E nthalp y is equal t o the v alue of En thalp y.The unit of measur emen t is sp ecific-ener gy. PDF Table H eat Loss/G ain is giv en b y the f ollowing equa tion: (42.24) if the c ell en thalp y is less than the adiaba tic en thalp y, and b y the f ollowing equa tion: (42.25) if the c ell en thalp y is higher than adiaba tic wher e = total en thalp y = the PDF Table A diaba tic En thalp y Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3014Field F unction D efinitions = the minimum En thalp y defined in the PDF table = the maximum En thalp y defined in the PDF table The PDF Table H eat Loss/G ain is dimensionless and r anges in v alue fr om -1, when is equal t o , to +1, when is equal t o . If H is equal t o the adiaba tic en thalp y it will b e 0. Phases ... contains quan tities f or reporting the v olume fr action of each phase . See Modeling M ultiphase F lows (p.2091 ) for details . Pitchwise C oordina te (in the Mesh... categor y) is the nor maliz ed (dimensionless) c oordina te in the cir cumf erential (pit chwise) direction. Its value v aries fr om to . Porous D eposition R ate of species-n (in the Species ... categor y) is the amoun t of a sur face sp ecies tha t is dep osited on p orous z ones . Its unit quan tity is mass-flux . Preconditioning Ref erenc e Velocity (in the Velocity... categor y) is the r eference velocity used in the c oupled solv er’s preconditioning algor ithm. See Preconditioning in the Theor y Guide for details . Premix ed C ombustion... contains quan tities r elated t o the pr emix ed c ombustion mo del, which is descr ibed in Modeling P remix ed Combustion (p.1749 ). Pressur e... includes quan tities r elated t o a nor mal f orce per unit ar ea (the impac t of the gas molecules on the sur faces of a c ontrol volume). Pressur e Coefficien t (in the Pressur e... categor y) is a dimensionless par amet er defined b y the equa tion (42.26) and is the r eference dynamic pr essur e defined b y .The r eference pr essur e, densit y, and v elocity are defined in the Reference Values Task P age (p.3601 ). Pressur e Spectrum Im n (in the Acoustics ... categor y) is the imaginar y par t of the c omple x Fourier amplitudes f or Fourier mo de n, as calcula ted b y the Acoustic S ources FFT D ialog Box (p.3652 ). See FFT of A coustic S ources: Band A naly sis and Exp ort of Sur face Pressur e Spectra (p.1894 ) for details . Pressur e Spectrum Re n (in the Acoustics ... categor y) is the r eal par t of the c omple x Fourier amplitudes f or Fourier mo de n, as calcula ted b y the Acoustic S ources FFT D ialog Box (p.3652 ). See FFT of A coustic S ources: Band A naly sis and Export of Sur face Pressur e Spectra (p.1894 ) for details . Produc t Formation R ate (in the Premix ed C ombustion... categor y) is the sour ce term in the pr ogress v ariable tr ansp ort equa tion ( in Equa tion 9.1 in the Theor y Guide ). Its unit quan tity is time-in verse . 3015Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Alphab etical Listing of F ield Variables and Their D efinitionsProduc tion of k (in the Turbulenc e... categor y) is the r ate of pr oduc tion of turbulenc e kinetic ener gy (times densit y). Its unit quan tity is turb-k inetic-ener gy-pr oduc tion . For multiphase mo dels , this v alue c orresponds t o the selec ted phase in the Phase drop-do wn list. Produc tion of laminar k (in the Turbulenc e... categor y) is the pr oduc tion of laminar k inetic ener gy used in the - - transition model. See Transp ort Equa tions f or the k-k l-ω Model in the Theor y Guide f or mor e details ( Equa tion 4.150 ). Progress Variable (in the Premix ed C ombustion... categor y) is a nor maliz ed mass fr action of the c ombustion pr oduc ts ( ) or unbur nt mix ture pr oduc ts ( ), as defined b y Equa tion 10.3 in the Theor y Guide . Progress Variable Varianc e (in the Premix ed C ombustion... categor y) is the v arianc e of the r eaction pr ogress v ariable tha t is solv ed in the par tially-pr emix ed c ombustion mo del. Properties ... includes ma terial pr operty quan tities f or fluids and solids . Q C riterion (in the Turbulenc e... categor y) is a p ostpr ocessing quan tity used f or visual insp ection of turbulenc e structures. Rate of C oagula tion (in the Soot... categor y) is the r ate of the c oagula tion of so ot par ticles . Rate of NO (in the NOx... categor y) is the o verall rate of f ormation of NO due t o all ac tive NO f ormation pa thw ays (for example , ther mal, prompt , and so on). Rate of N uclea tion (in the Soot... categor y) is the r ate of nuclea tion of the so ot par ticles . Rate of N uclei (in the Soot... categor y) is the o verall rate of f ormation of nuclei. Rate of N2OP ath NO (in the NOx... categor y) is the r ate of f ormation of NO due t o the N2O pa thw ay only (only a vailable when N2O pa thw ay is ac tive). Rate of O xida tion (in the Soot... categor y) is the r ate of o xida tion of the so ot par ticles . Rate of P rompt NO (in the NOx... categor y) is the r ate of f ormation of NO due t o the pr ompt pa thw ay only (only a vailable when pr ompt pa thw ay is ac tive). Rate of Rebur n NO (in the NOx... categor y) is the r ate of f ormation of NO due t o the r ebur n pa thw ay only (only a vailable when rebur n pa thw ay is ac tive). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3016Field F unction D efinitionsRate of SNCR NO (in the NOx... categor y) is the r ate of f ormation of NO due t o the SNCR pa thw ay only (only a vailable when SNCR pa thw ay is ac tive). Rate of S oot (in the Soot... categor y) is the o verall rate of f ormation of so ot mass . Rate of S oot M ass N uclea tion (in the Soot... categor y) is the o verall rate of so ot nuclea tion. Rate of S urface Growth (in the Soot... categor y) is the r ate of the so ot par ticle sur face gr owth due t o reactions a t soot par ticle surface. Rate of Thermal NO (in the NOx... categor y) is the r ate of f ormation of NO due t o the ther mal pa thw ay only (only a vailable when ther mal pa thw ay is ac tive). Rate of F uel NO (in the NOx... categor y) is the r ate of f ormation of NO due t o the fuel pa thw ay only (only a vailable when fuel pa thw ay is ac tive). Rate of USER NO (in the NOx... categor y) is the r ate of f ormation of NO due t o user defined r ates only (only a vailable when user-defined func tion r ates ar e added). Radial C oordina te (in the Mesh... categor y) is the length of the r adius v ector in the p olar c oordina te sy stem. The r adius v ector is defined b y a line segmen t between the no de and the axis of r otation. You c an define the r otational axis in the Fluid D ialog Box (p.3457 ). (See also Velocity Reporting Options (p.2961 ).) The unit quan tity for Radial Coordina te is length . Radial P ull Velocity (in the Solidific ation/M elting ... categor y) is the r adial-dir ection c omp onen t of the pull v elocity for the solid ma terial in a c ontinuous c asting pr ocess. Its unit quan tity is velocity. Radial Velocity (in the Velocity... categor y) is the c omp onen t of v elocity in the r adial dir ection. (See Velocity Reporting Options (p.2961 ) for details .) The unit quan tity for Radial Velocity is velocity. For multiphase mo dels , this value c orresponds t o the selec ted phase in the Phase drop-do wn list. Radial-W all S hear S tress (in the Wall F luxes... categor y) is the r adial c omp onen t of the f orce ac ting tangen tial t o the sur face due to friction. Its unit quan tity is pressur e. Radia tion... includes quan tities r elated t o radia tion hea t transf er. See Modeling R adia tion (p.1489 ) for details ab out the radia tion mo dels a vailable in ANSY S Fluen t. Radia tion H eat Flux (in the Wall F luxes... categor y) is the r ate of r adia tion hea t transf er thr ough the c ontrol sur face. It is c alcu- lated b y the solv er acc ording t o the sp ecified r adia tion mo del. Heat flux out of the domain is nega tive, and hea t flux in to the domain is p ositiv e.The unit quan tity for Radia tion H eat Flux is hea t-flux . 3017Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Alphab etical Listing of F ield Variables and Their D efinitionsRadia tion In tensit y.Normaliz ed S td D eviation (in the Radia tion... categor y) is the sta tistic al standar d de viation f or the spher ical mean r adia tion in tensit y. Radia tion Temp erature (in the Radia tion... categor y) is the quan tity , defined b y (42.27) wher e is the Inciden t Radia tion .The unit quan tity for Radia tion Temp erature is temp erature. Rate of Reac tion-n (in the Reac tions ... categor y) is the eff ective rate of pr ogress of th reaction. For the finit e-rate mo del, the value is the same as the Kinetic R ate of Reac tion-n . For the edd y-dissipa tion mo del, the v alue is equiv alen t to the Turbulen t Rate of Reac tion-n . For the finit e-rate/edd y-dissipa tion mo del, it is the lesser of the t wo. For par ticle r eactions it is the global r ate of the par ticle r eaction n e xpressed in k mol/s/m3.This is comput ed as wher e is the r ate of par ticle sp ecies depletion (or gener ation) giv en b y Equa tion 7.73 in the Theor y Guide , is the par ticle sp ecies molecular w eigh t, and is the c ell v olume . Reac tions ... includes quan tities r elated t o finit e-rate reactions . See Modeling S pecies Transp ort and F inite-Rate Chemistr y (p.1613 ) for inf ormation ab out mo deling finit e-rate reactions . Reac tor N et M ass F raction of Species-n (in the Species ... categor y) is the mass of a sp ecies p er unit mass of the mix ture in the r eactor net work. Reac tor N et Temp erature (in the Species ... categor y) is the c omput ed t emp erature of the r eactor net work. Reac tor N et Z one ID (in the Species ... categor y) a unique iden tifier asso ciated with each r eactor net work. Reduc ed Temp erature (in the Properties ... categor y) is the r atio of the fluid t emp erature divided b y the cr itical temp er- ature .The r educ ed t emp erature is a vailable only with the A ngier-R edlich-K wong r eal gas mo del. Reduc ed P ressur e (in the Properties ... categor y) is the r atio of the fluid pr essur e divided b y the cr itical pr essur e . The r educ ed pr essur e is a vailable only with the A ngier-R edlich-K wong r eal gas mo del. Reflec ted R adia tion F lux (B and-n) (in the Wall F luxes... categor y) is the amoun t of r adia tive hea t flux r eflec ted b y a semi-tr anspar ent wall for a par ticular band of r adia tion. Its unit quan tity is hea t-flux . Reflec ted Visible S olar F lux, Reflec ted IR S olar F lux (in the Wall F luxes... categor y) is the amoun t of solar hea t flux r eflec ted b y a semi-tr anspar ent wall or porous jump b oundar y for a visible or infr ared (IR) r adia tion. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3018Field F unction D efinitionsRefr active Inde x (in the Radia tion... categor y) is a nondimensional par amet er defined as the r atio of the sp eed of ligh t in a vacuum t o tha t in a ma terial. See Specular S emi-T ranspar ent Walls in the Theor y Guide for details . Rela tive Axial Velocity (in the Velocity... categor y) is the axial-dir ection c omp onen t of the v elocity relative to the r eference frame motion. See Velocity Reporting Options (p.2961 ) for details .The unit quan tity for Rela tive Axial Velocity is velocity. Rela tive Humidit y (in the Species ... categor y) is the r atio of the par tial pr essur e of the w ater vapor ac tually pr esen t in an air- water mix ture to the sa turation pr essur e of w ater vapor a t the mix ture temp erature. ANSY S Fluen t comput es the sa turation pr essur e, , from the f ollowing equa tion [101] (p.4010 ): (42.28) wher e = 22.089 MP a = 647.286 K = = = = = = = = = 0.01 = 338.15 K Rela tive M ach N umb er (in the Velocity... categor y) is the nondimensional r atio of the r elative velocity and sp eed of sound . Rela tive Radial Velocity (in the Velocity... categor y) is the r adial-dir ection c omp onen t of the v elocity relative to the r eference frame motion. (See Velocity Reporting Options (p.2961 ) for details .) The unit quan tity for Rela tive Radial Velocity is velocity. Rela tive Swirl Velocity (in the Velocity... categor y) is the tangen tial-dir ection c omp onen t of the v elocity relative to the r eference frame motion, in an axisymmetr ic swir ling flo w. (See Velocity Reporting Options (p.2961 ) for details .) The unit quan tity for Rela tive Swirl Velocity is velocity. 3019Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Alphab etical Listing of F ield Variables and Their D efinitionsRela tive Tangen tial Velocity (in the Velocity... categor y) is the tangen tial-dir ection c omp onen t of the v elocity relative to the r eference frame motion. (See Velocity Reporting Options (p.2961 ) for details .) The unit quan tity for Rela tive Tangen tial Velocity is velocity. Rela tive Total P ressur e (in the Pressur e... categor y) is the stagna tion pr essur e comput ed using r elative velocities inst ead of absolut e velocities; tha t is, for inc ompr essible flo ws the d ynamic pr essur e would b e comput ed using the r elative velocities . (See Velocity Reporting Options (p.2961 ) for mor e inf ormation ab out r elative velocities .) The unit quan tity for Rela tive Total P ressur e is pressur e. Rela tive Total Temp erature (in the Temp erature... categor y) is the stagna tion t emp erature comput ed using r elative velocities inst ead of absolut e velocities . (See Velocity Reporting Options (p.2961 ) for mor e inf ormation ab out r elative velocities .) The unit quan tity for Rela tive Total Temp erature is temp erature. Rela tive Velocity Angle (in the Velocity... categor y) is similar t o the Velocity Angle except tha t it uses the r elative tangen tial v e- locity, and is defined as (42.29) Its unit quan tity is angle . Rela tive Velocity M agnitude (in the Velocity... categor y) is the magnitude of the r elative velocity vector inst ead of the absolut e velocity vector.The r elative velocity ( ) is the diff erence between the absolut e velocity ( ) and the mesh v elocity. For simple r otation, the r elative velocity is defined as (42.30) wher e is the angular v elocity of a mo ving r eference frame ab out the or igin and is the p osition vector. (See Velocity Reporting Options (p.2961 ) for details .) The unit quan tity for Rela tive Velocity Magnitude is velocity. Rela tive X Velocity, Rela tive Y Velocity, Rela tive Z Velocity (in the Velocity... categor y) ar e the -, -, and -direction c omp onen ts of the v elocity relative to the r ef- erence frame motion. (See Velocity Reporting Options (p.2961 ) for details .) The unit quan tity for these v ariables is velocity. Residuals ... contains diff erent quan tities f or the pr essur e-based and densit y-based solv ers: In the densit y-based solv ers, this c ategor y includes the c orrections t o the pr imitiv e variables pr essur e, velocity, temp erature, and sp ecies , as w ell as the time r ate of change of the c orrections t o these primitiv e variables f or the cur rent iteration (tha t is, residuals). Corrections ar e the changes in the variables b etween the cur rent and pr evious it erations and r esiduals ar e comput ed b y dividing a cell’s correction b y its ph ysical time st ep.The t otal r esidual f or each v ariable is the summa tion of the E uler, visc ous, and dissipa tion c ontributions .The dissipa tion c omp onen ts ar e the v ector c om- ponen ts of the flux-lik e, face-based dissipa tion op erator. In the pr essur e-based solv er, only the Mass Imbalanc e in each c ell is r eported (unless y ou ha ve request ed others , as descr ibed in Postpr ocessing R esidual Values (p.2655 )). At convergenc e, this quan tity should b e small c ompar ed t o the a verage mass flo w rate. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3020Field F unction D efinitionsReverse Reac tion R ate of PDF scalar-n (in the Premix ed C ombustion... categor y) is the r ate of c onsumption of species-n due t o reverse r eac- tions f or sc alar in k g/m3/s ( in Equa tion 10.16 in the Fluent Theor y Guide ). (The name of the PDF scalar will r eplac e PDF scalar-n in Reverse Reac tion R ate of PDF scalar-n .) RMS (species-n ) Mass F raction (in the Species ... categor y) is the r oot mean squar e value of the mass of a sp ecies p er unit mass of the mixture. RMSE n (in the Stead y Statistics ... or Unstead y Statistics ... categor y) is the r oot mean squar ed er ror v alue of a solution v ariable n (for e xample ,Static P ressur e). See Performing S teady-State Calcula tions (p.2614 ) and Postpr ocessing f or Time-D ependen t Problems (p.2645 ) for details . RMSE- cff_n (in the Stead y Statistics ... or Unstead y Statistics ... categor y) is the r oot mean squar ed er ror v alue of a cust om field func tion cff_n (for e xample ,uns-cust om-func tion-0 ). See Performing S teady-State Calcula- tions (p.2614 ) and Postpr ocessing f or Time-D ependen t Problems (p.2645 ) for details . RMS DPM n (in the Stead y Statistics ... or Unstead y Statistics ... categor y) is the r oot mean squar e value of a discr ete phase v ariable n (for e xample ,Volume F raction ). See Performing S teady-State Calcula tions (p.2614 ) and Postpr ocessing f or Time-D ependen t Problems (p.2645 ) for details . Rothalp y (in the Temp erature... categor y) is defined as (42.31) wher e is the en thalp y, is the r elative velocity magnitude , and is the magnitude of the r ota- tional v elocity . Saturation Temp erature n (in the Phase In teraction... categor y) is the sa turation t emp erature of the nth mass tr ansf er mechanism that you defined .This it em is a vailable only f or the e vaporation-c ondensa tion mo del. See Including S emi- Mechanistic B oiling (p.2199 ) for mor e inf ormation ab out the semi-mechanistic b oiling mo del. Scalar-n (in the User D efined Sc alars ... categor y) is the v alue of the th scalar quan tity you ha ve defined as a user- defined sc alar. See the Fluen t Customiza tion M anual for mor e inf ormation ab out user-defined sc alars . Scalar D issipa tion (in the Pdf... categor y) is one of t wo par amet ers tha t descr ibes the sp ecies mass fr action and t emp erature for a laminar flamelet in mix ture fraction spac es. It is defined as (42.32) wher e is the mix ture fraction and is a r epresen tative diffusion c oefficien t (see The F lamelet Concept in the Theor y Guide for details). Its unit quan tity is time-in verse . 3021Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Alphab etical Listing of F ield Variables and Their D efinitionsScalar M ass F raction of species-n (in the Premix ed C ombustion... categor y) is the mass fr action of the species-n in the PDF mix ture tha t is solv ed as a tr ansp orted sc alar in the par tially-pr emix ed FGM mo del. (The name of the sp ecies will r eplac e species-n in Scalar M ass F raction of species-n ). Scattering C oefficien t (in the Radia tion... categor y) is the pr operty of a medium tha t descr ibes the amoun t of sc attering of ther mal r adia tion p er unit pa th length f or pr opaga tion in the medium. It can b e interpreted as the in verse of the mean fr ee pa th tha t a phot on will tr avel before under going sc attering (if the sc attering c oefficien t does not v ary along the pa th).The unit quan tity for Scattering C oefficien t is length-in verse . Secondar y M ean M ixture Fraction (in the Pdf... categor y) is the mean r atio of the sec ondar y str eam mass fr action t o the sum of the fuel, secondar y str eam, and o xidan t mass fr actions . It is the sec ondar y-str eam c onser ved sc alar tha t is c alcula ted by the non-pr emix ed c ombustion mo del. See Definition of the M ixture Fraction in the Theor y Guide . Secondar y M ixture Fraction Varianc e (in the Pdf... categor y) is the v arianc e of the sec ondar y str eam mix ture fraction tha t is solv ed f or in the non-pr emix ed c ombustion mo del. See Definition of the M ixture Fraction in the Theor y Guide . Sensible E nthalp y (in the Temp erature... categor y) is a vailable when an y of the sp ecies mo dels ar e ac tive and displa ys only the ther mal (sensible) en thalp y. Sensitivit y to Body Force X-C omp onen t (Cell Values) ,Sensitivit y to Body Force Y-C omp onen t (Cell Values) , and Sensitivit y to Body Force Z-C omp onen t (Cell Values) (in the Sensitivities ... categor y) ar e the c omp onen ts of the adjoin t velocity pr imitiv e field .These fields can b e interpreted as the magnitude of the sensitivit y of the obser vable t o comp onen ts of a b ody force per unit v olume . Consider a b ody force distr ibution, expressed as a f orce per unit v olume .The v olume in- tegral of the v ector pr oduc t of tha t distr ibution with the c omp onen ts of this field giv es a first-or der estima te of the net eff ect of the b ody force on the obser vation. Sensitivit y to Boundar y Heat Flux (in the Sensitivities ... categor y) is a vailable when the ener gy adjoin t equa tion is solv ed and is defined on walls wher e a hea t flux b oundar y condition is imp osed .The field sho ws the sensitivit y of the obser vation of in terest t o variations in the b oundar y hea t flux thr ough the w all. Its pr operties ar e analo gous t o those of S ensitivit y to Boundar y Temp erature. Sensitivit y to Boundar y Pressur e (in the Sensitivities ... categor y) is defined on b oundar ies wher e ther e is a user-sp ecified pr essur e as par t of a b oundar y condition, such as on a pr essur e outlet. The field sho ws the sensitivit y of the obser vation of in terest t o variations in the b oundar y pr essur e acr oss the flo w boundar y. It is in teresting t o not e tha t even though the or iginal b oundar y condition sp ecific ation ma y be for a unif orm pr essur e on the domain boundar y, the eff ect of a non-unif orm pr essur e perturba tion is a vailable ,The eff ect of an y sp ecific boundar y pr essur e change c an b e estima ted as an in tegral of the pr oduc t of the change t o the pr essur e with the plott ed sensitivit y field .Viewing this field will also indic ate whether or not the assumption of a unif orm pr essur e is adequa te for the simula tion. Sensitivit y to Boundar y Temp erature (in the Sensitivities ... categor y) is a vailable when the ener gy adjoin t equa tion is solv ed and is defined on boundar ies wher e a t emp erature boundar y condition is applied .This includes w alls, velocity inlets , mass- flow inlets , pressur e inlets , and pr essur e outlets wher e a backflo w temp erature ma y be sp ecified .The field shows the sensitivit y of the obser vation of in terest t o variations in the b oundar y temp erature acr oss the boundar ies. Note tha t even if the or iginal b oundar y condition sp ecific ation is f or a unif orm temp erature Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3022Field F unction D efinitionson the b oundar y, the eff ect of a non-unif orm temp erature perturba tion is a vailable .The eff ect of an y specific b oundar y temp erature change c an b e estima ted as an in tegral of the pr oduc t of the change t o the t emp erature with the plott ed sensitivit y field .This field c an b e used t o indic ate whether or not the assumption of a unif orm temp erature is adequa te for the simula tion. Sensitivit y to Boundar y X-V elocity,Sensitivit y to Boundar y Y-V elocity, and Sensitivit y to Boundar y Z- Velocity (in the Sensitivities ... categor y) ar e defined on those b oundar ies wher e a user-sp ecific ation of a b oundar y velocity is made f or the or iginal flo w calcula tion. This includes no-slip w alls.The field sho ws ho w sensitiv e the obser vable of in terest is t o changes in the b oundar y velocity at an y point. It is in teresting t o not e tha t even though the or iginal b oundar y condition sp ecific ation ma y be for a unif orm velocity on the domain boundar y, the eff ect of a non-unif orm velocity perturba tion is a vailable ,The eff ect of an y sp ecific b oundar y velocity change c an b e estima ted as an in tegral of the v ector pr oduc t of the change t o the v elocity with the plott ed sensitivit y field . A plot of this quan tity on a v elocity inlet , for e xample , can b e very useful f or assessing whether or not the inlet is p ositioned t oo close t o key par ts of the sy stem. That is, it addr esses the question of whether or not the flo w domain is t oo small t o achie ve a succ essful c omputa tion of the performanc e measur e of in terest.Viewing this field will also indic ate whether or not the assumption of a unif orm inflo w is adequa te. Sensitivit y to Energy Sour ces (C ell Values) (in the Sensitivities ... categor y) is a vailable when the ener gy adjoin t equa tion is solv ed and is the pr imitiv e adjoin t temp erature field . It can b e interpreted as the sensitivit y of the obser vable with r espect to ther mal ener gy sour ces or sinks p er unit v olume in the domain. Sensitivit y to Flow Blo ckage (in the Sensitivities ... categor y) is pr ovided as a c onvenien t tool for iden tifying p ortions of the flo w domain wher e the in troduc tion of blo ckages or obstr uctions in the flo w can aff ect the obser vation of in terest. Consider a blo ckage in the flo w tha t gener ates a r eaction f orce on the flo w tha t is pr oportional t o the local flo w sp eed, and ac ting in the opp osite dir ection t o the lo cal flo w: wher e is a lo cal coefficien t for the r eaction f orce.The lo cal contribution of this f orce on the obser vation of in terest is de- termined b y the v ector pr oduc t of this f orce with the adjoin t velocity field .The flo w blo ckage field tha t is plott ed is , namely the nega tive of the v ector pr oduc t of the flo w velocity and the adjoin t velocity (Cell Value). Sensitivit y to M ass S our ces (C ell Values) (in the Sensitivities ... categor y) is the pr imitiv e adjoin t pressur e field .This field c an b e interpreted as the sensitivit y of the obser vable with r espect to mass sour ces or sinks in the domain. Consider a mass sour ce / sink distr ibution, expressed as mass flo w rate per unit v olume .The v olume in tegral of tha t distr ibution, weigh ted b y the lo cal value of this field , gives the eff ect of the sour ces / sinks on the obser vation. When plott ed on a b oundar y, this field indic ates the eff ect of the addition or r emo val of fluid fr om the domain upon the quan tity of in terest. It is imp ortant to not e tha t in this sc enar io the eff ect of the momen tum of the fluid tha t is added or r emo ved is not tak en in to acc oun t.The b oundar y velocity sensitivit y should b e plott ed if tha t eff ect is also of in terest. Sensitivit y to Visc osit y (in the Sensitivities ... categor y) sho ws the sensitivit y of the quan tity of in terest t o variations in the turbulen t effective visc osity for a turbulen t problem, or the laminar visc osity in a laminar c ase.The sensitivit y is normaliz ed b y the c ell v olume t o acc oun t for cell siz e variations in the mesh. Shap e Sensitivit y M agnitude (in the Sensitivities ... categor y) is the magnitude of the sensitivit y of the obser vable with r espect to a deformation applied t o the mesh (b oth b oundar y and in terior mesh). When plott ed on the sur face of a body the lo cations wher e this quan tity is lar ge indic ates wher e small changes t o the sur face shap e can 3023Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Alphab etical Listing of F ield Variables and Their D efinitionshave a lar ge eff ect on the obser vable of in terest. If the shap e sensitivit y magnitude is small then the eff ect of shap e changes in this r egion c an b e expected t o ha ve a small eff ect on the obser vable of in terest.When viewing this field , it is of ten obser ved tha t the magnitude v aries b y man y or ders of magnitude . Contour plots will clear ly dr aw attention t o regions with the highest sensitivit y (of ten shar p edges and c orners). However, it should b e rememb ered tha t a r elatively small sur face mo vemen t tha t is distr ibut ed o ver a large ar ea c an ha ve a cumula tive eff ect tha t is lar ge. Shap e Sensitivit y X-C omp onen t,Shap e Sensitivit y Y-C omp onen t, and Shap e Sensitivit y Z-C omp onen t (in the Sensitivities ... categor y) ar e the individual c omp onen ts of the sensitivit y of the obser vable of in terest with r espect to the mesh no de lo cations . It is plott ed as c ell da ta and is c omput ed as the a verage of the nodal sensitivities f or a giv en c ell, divided b y the c ell v olume . Note tha t for this discr ete adjoin t solv er the sensitivit y of the r esult with r espect to no de lo cations b oth on and off b oundar ies is c omput ed.The nor- maliza tion b y cell v olume indic ates tha t the fields tha t are plott ed ar e the w eigh ting fac tors f or a c ontinuous spatial def ormation field . (Note tha t the no dal sensitivit y da ta itself is used when mesh mor phing is p er- formed , and pr edic tions ab out the eff ect of shap e changes ar e made .) Shielding F unc tion f or SBES or SDES (in the Turbulenc e... categor y) is the shielding func tion used as par t of the S tress-B lended E ddy Simula tion turbulenc e mo del and the S hielded D etached E ddy Simula tion turbulenc e mo del. For details , see Stress-B lended E ddy Simula tion (SBES) and Shielded D etached E ddy Simula tion (SDES) in the Fluent Theor y Guide , as w ell as Including the SDES or SBES M odel with BSL, SST , and Transition SST M odels (p.1444 ). Sigma X X, Sigma YY, Sigma X Y, Sigma ZZ, Sigma YZ, Sigma XZ, (in the Structure... categor y) ar e the c omp onen ts of the str ess t ensor .These v ariables ar e intended only for solid z ones and/or their adjac ent walls in in trinsic fluid-str ucture interaction (FSI) simula tions . Site fraction of soot species-n (in the Soot... categor y) is the r atio of moles of a so ot sp ecies o ver the t otal moles of all so ot sp ecies . (The name of the so ot sp ecies will r eplac e soot species-n in Site fraction of soot species-n .) This quan tity is a vailable only with the M etho d of M omen ts mo del tha t uses the Detailed CHEMKIN F ormat soot mechanism. Skin F riction C oefficien t (in the Wall F luxes... categor y) is a nondimensional par amet er defined as the r atio of the w all shear str ess and the r eference dynamic pr essur e (42.33) wher e is the w all shear str ess, and and are the r eference densit y and v elocity defined in the Reference Values Task P age (p.3601 ). For multiphase mo dels , this v alue c orresponds t o the selec ted phase in the Phase drop-do wn list. Solar H eat Flux (in the Wall F luxes... categor y) is the r ate of solar hea t transf er thr ough the c ontrol sur face. Heat flux out of the domain is nega tive and hea t flux in to the domain is p ositiv e. Solidific ation/M elting ... contains quan tities r elated t o solidific ation and melting . Soot... contains quan tities r elated t o the Soot mo del, which is descr ibed in Soot F ormation (p.1854 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3024Field F unction D efinitionsSoot D ensit y (in the Soot... categor y) is the mass p er unit v olume of so ot.The unit quan tity is densit y. See Fuel NO x Formation in the Theor y Guide for details . Soot M ean D iamet er (in the Soot... categor y) is the a verage diamet er of the so ot par ticles .This quan tity is a vailable only with the M etho d of M omen ts mo del. Soot S urface Area (in the Soot... categor y) is the t otal sur face area of the so ot par ticles .This quan tity is a vailable only with the M etho d of M omen ts mo del. Soot Volume fr action (in the Soot... categor y) is the v olume fr action of so ot. Sound S peed (in the Properties ... categor y) is the ac oustic sp eed. It is c omput ed fr om . Its unit quan tity is velocity. Imp ortant Note tha t for the r eal gas mo dels the sound sp eed is c omput ed acc ordingly b y the ap- propriate equa tion of sta te formula tion. Sound dP/dt (in the Acoustics ... categor y) is the time der ivative of the S ound P ressur e. It is a vailable only when the acoustics w ave equa tion mo del is used . Its unit quan tity is pr essur e divided b y time . Sound P ressur e (in the Acoustics ... categor y) is the ac oustic pr essur e, resulting fr om the ac oustics w ave equa tion. It is available only when the ac oustics w ave equa tion mo del is used . Its unit quan tity is pr essur e. Sound P otential (in the Acoustics ... categor y) is the ac oustic p otential, which is a p otential of the ac oustics par ticle v elocity, resulting fr om the ac oustics w ave equa tion. It is a vailable only when the ac oustics w ave equa tion mo del is used . Its unit quan tity is v elocity times length. Sound S ponge L ayer M arker (in the Acoustics ... categor y) is the mar ker sho wing a sp onge r egion of the ac oustics w ave equa tion. It is available only when the ac oustics w ave equa tion mo del is used . Sound WaveEq M odel S our ce (in the Acoustics ... categor y) is the or iginal mo del sour ce term of the ac oustics w ave equa tion, before the applic ation of the time filt er. It is a vailable only when the ac oustics w ave equa tion mo del is used . Its unit quan tity is squar e of v elocity divided b y time . Sound WaveEq M odel S our ce M ask (in the Acoustics ... categor y) is the mar ker sho wing a mask ing r egion of the mo del sour ce term of the acoustics w ave equa tion. It is a vailable only when the ac oustics w ave equa tion mo del is used . Sound WaveEq M odel S our ce Smoothed (in the Acoustics ... categor y) is the mo del sour ce term of the ac oustics w ave equa tion, smo othed b y the time filt er. It is a vailable only when the ac oustics w ave equa tion mo del is used . Its unit quan tity is squar e of velocity divided b y time . 3025Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Alphab etical Listing of F ield Variables and Their D efinitionsSpanwise C oordina te (in the Mesh... categor y) is the nor maliz ed (dimensionless) c oordina te in the spanwise dir ection, from hub to casing . Its value v aries fr om to . species-n Sour ce Term (in the Species ... categor y) is the sour ce term in each of the sp ecies tr ansp ort equa tions due t o reactions . The unit quan tity is alw ays kg/m3-s. Species ... includes quan tities r elated t o sp ecies tr ansp ort and r eactions . Specific D issipa tion R ate (Omega) (in the Turbulenc e... categor y) is the r ate of dissipa tion of turbulenc e kinetic ener gy in unit v olume and time . Its unit quan tity is time-in verse . Specific H eat (Cp) (in the Properties ... categor y) is the ther modynamic pr operty of sp ecific hea t at constan t pressur e. It is defined as the r ate of change of en thalp y with t emp erature while pr essur e is held c onstan t. Its unit quan tity is specific-hea t. Specific H eat Ratio (gamma) (in the Properties ... categor y) is the r atio of sp ecific hea t at constan t pressur e to the sp ecific hea t at constan t volume . Spino dal Temp erature (in the Properties ... categor y) is the t emp erature of the gas phase a t which the der ivative of pr essur e with respect to molar v olume b ecomes p ositiv e.The spino dal t emp erature defines the p oint beyond which the equa tion of sta te is no longer v alid. If the t emp erature of y our c ase appr oaches the spino dal t emp erature in some r egions , this indic ates tha t the flo w conditions in these r egions pr obably fall inside the sa turation dome .The Spino dal Temp erature is a vailable only with the C ubic E qua tion of S tate Real G as mo dels . SPL f or O ctave Band a txHz (dB) (in the Acoustics ... categor y) is the sur face pr essur e level (in decib els) of the standar d technic al octave band a t the o ctave central frequenc y x, as c alcula ted b y the Acoustic S ources FFT D ialog Box (p.3652 ). See FFT of A coustic S ources: Band A naly sis and Exp ort of Sur face Pressur e Spectra (p.1894 ) for details . Note tha t the tr ansf ormation t o the decib el units is done b y default using the standar d ac oustic r eference pr essur e value of 2 x 10-5 Pa; you c an change this v alue using the Acoustics M odel D ialog Box (p.3371 ). SPL f or 1/3-O ctave Band a txHz (dB) (in the Acoustics ... categor y) is the sur face pr essur e level (in decib els) of the standar d technic al 1/3-o ctave band a t the 1/3-o ctave central frequenc y x, as c alcula ted b y the Acoustic S ources FFT D ialog Box (p.3652 ). See FFT of A coustic S ources: Band A naly sis and Exp ort of Sur face Pressur e Spectra (p.1894 ) for details . Note that the tr ansf ormation t o the decib el units is done b y default using the standar d ac oustic r eference pressur e value of 2 x 10-5 Pa; you c an change this v alue using the Acoustics M odel D ialog Box (p.3371 ). SPL f or C onst Width B and n(dB) (in the Acoustics ... categor y) is the sur face pr essur e level (in decib els) of the user-defined c onstan t band n, as c alcula ted b y the Acoustic S ources FFT D ialog Box (p.3652 ). See FFT of A coustic S ources: Band A naly sis and Exp ort of Sur face Pressur e Spectra (p.1894 ) for details . Note tha t the tr ansf ormation t o the decib el units is done b y default using the standar d ac oustic r eference pr essur e value of 2 x 10-5 Pa; you c an change this value using the Acoustics M odel D ialog Box (p.3371 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3026Field F unction D efinitionsStatic P ressur e (in the Pressur e... categor y) is the sta tic pr essur e of the fluid . It is a gauge pr essur e expressed r elative to the pr escr ibed op erating pr essur e.The absolut e pr essur e is the sum of the Static P ressur e and the op er- ating pr essur e. Its unit quan tity is pressur e. Static Temp erature (in the Temp erature... and Premix ed C ombustion... categor ies) is the t emp erature in the fluid / solid . Its unit quan tity is temp erature. For a w all or shado w w all sur face, the Static Temp erature is the t emp erature of the adjac ent fluid / solid c ells; for a shell sur face (see Postpr ocessing S hells (p.1487 )), it is the t emp erature of the shell la yer cells on the c0 side (tha t is, the side closer t o the asso ciated w all sur face). Note tha t Static Temp erature will app ear in the Premix ed C ombustion... categor y only f or adia- batic pr emix ed c ombustion c alcula tions . See Postpr ocessing f or P remix ed C ombustion C alcula- tions (p.1756 ). Stead y Statistics ... includes mean and r oot mean squar e error (RMSE) v alues of solution v ariables and cust om field func tions derived fr om st eady sta te flo w calcula tions (with Data S ampling f or S tead y Statistics enabled). Stored C ell P artition (in the Cell Inf o... categor y) is an in teger iden tifier designa ting the par tition t o which a par ticular c ell b e- longs . In pr oblems in which the mesh is divided in to multiple par titions t o be solv ed on multiple pr ocessors using the par allel v ersion of ANSY S Fluen t, the par tition ID c an b e used t o det ermine the e xtent of the various gr oups of c ells.The ac tive cell par tition is used f or the cur rent calcula tion, while the st ored c ell partition (the last par tition p erformed) is used when y ou sa ve a c ase file . See Partitioning the M esh Manually and B alancing the L oad (p.3071 ) for mor e inf ormation. Strain R ate (in the Derivatives... categor y) relates shear str ess t o the visc osity. Also c alled the shear r ate ( in Equa- tion 8.35 (p.1112 )), the str ain r ate is r elated t o the sec ond in variant of the r ate-of-def ormation t ensor . Its unit quan tity is time-in verse . In 3D C artesian c oordina tes, the str ain r ate, , is defined as (42.34) For multiphase mo dels , this v alue c orresponds t o the selec ted phase in the Phase drop-do wn list. Stream F unc tion (in the Velocity... categor y) is f ormula ted as a r elation b etween the str eamlines and the sta temen t of conser vation of mass . A str eamline is a line tha t is tangen t to the v elocity vector of the flo wing fluid . For a 2D planar flo w, the str eam func tion, , is defined such tha t (42.35) constan t values of str eam func tion defining t wo str eamlines is the mass r ate of flo w b etween the streamlines . The accur acy of the str eam func tion c alcula tion is det ermined b y the t ext command /dis- play/set/n-stream-func . 3027Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Alphab etical Listing of F ield Variables and Their D efinitionsStretch F actor (in the Premix ed C ombustion... categor y) is a nondimensional par amet er tha t is defined as the pr obabilit y of unquenched flamelets ( in Equa tion 9.14 in the Theor y Guide ). Subcritical C ondition (in the Properties ... categor y) has a v alue of 1 if the flo w condition is sub critical and 0 if the flo w condition is sup ercritical and is a vailable with the C ubic E qua tion of S tate Real G as mo dels . Subgrid D issipa tion R ate (in the Turbulenc e... categor y) is the turbulenc e dissipa tion r ate of the unr esolv ed eddies , , only active for the LES and K inetic Ener gy Sub grid-Sc ale M odel. It is defined as (42.36) Its unit quan tity is turbulen t-ener gy-diss-r ate. Subgrid D ynamic P randtl N umb er (in the Turbulenc e... categor y) is used in the c alcula tion of the sub grid-sc ale turbulen t flux of a sc alar , see Sub grid-Sc ale M odels in the Theor y Guide ,Equa tion 4.277 . Subgrid D ynamic Sc of S pecies (in the Turbulenc e... categor y) is used in the c alcula tion of the sub grid-sc ale turbulen t flux f or S pecies (see Sub grid D ynamic P randtl N umb er). Subgrid D ynamic Visc osit y Const (in the Turbulenc e... categor y) is the S magor insk y mo del c onstan t as det ermined b y the d ynamic pr ocedur e descr ibed in Dynamic S magor insk y-Lilly M odel in the Theor y Guide ). Additional inf ormation with r espect to the Emb edded LES (E-LES) mo del c an b e found in Postpr ocessing f or Turbulen t Flows (p.1456 ). Subgrid F ilter L ength (in the Turbulenc e... categor y) is a mixing length f or sub grid sc ales of the LES turbulenc e mo del (defined as in Equa tion 4.280 in the Theor y Guide ). Subgrid K inetic E nergy (in the Turbulenc e... categor y) is the turbulenc e kinetic ener gy per unit mass of the unr esolv ed eddies , , calcula ted using a tr ansp ort equa tion, only ac tive for the LES and K inetic Ener gy Sub grid-Sc ale M odel. It is defined as (42.37) Additional inf ormation with r espect to the Emb edded LES (E-LES) mo del c an b e found in Postpr o- cessing f or Turbulen t Flows (p.1456 ). Its unit quan tity is turbulen t-kinetic-ener gy. Subgrid Test–F ilter L ength (in the Turbulenc e... categor y) is the t est filt er width descr ibed in Dynamic S magor insk y-Lilly M odel in the Theor y Guide ). Additional inf ormation with r espect to the Emb edded LES (E-LES) mo del c an b e found in Postpr ocessing f or Turbulen t Flows (p.1456 ). Subgrid Turbulen t Visc osit y (in the Turbulenc e... categor y) is the turbulen t (dynamic) visc osity of the fluid c alcula ted using the LES turbulenc e mo del. It expresses the pr oportionalit y between the anisotr opic par t of the sub grid-sc ale str ess tensor and the r ate-of-str ain t ensor . (See Equa tion 4.271 in the Theor y Guide .) Its unit quan tity is visc osit y. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3028Field F unction D efinitionsSubgrid Turbulen t Visc osit y Ratio (in the Turbulenc e... categor y) is the r atio of the sub grid turbulen t visc osity of the fluid t o the laminar viscosity, calcula ted using the LES turbulenc e mo del. Subt est K inetic E nergy (in the Turbulenc e... categor y) is the turbulenc e kinetic ener gy of filt ered eddies , , only ac tive for the LES and K inetic Ener gy Sub grid-Sc ale M odel. It is defined as (42.38) with being the nor mal c omp onen ts of the L eonar d str ess. Its unit quan tity is turbulen t-kinetic-ener gy Surface Acoustic P ower (in the Acoustics ... categor y) is the Acoustic P ower per unit ar ea gener ated b y boundar y layer turbulenc e (see Equa tion 15.35 in the Theor y Guide ). It is a vailable only when the Broadband N oise S our ces acoustics mo del is b eing used . Its unit quan tity is power per area. Surface Acoustic P ower L evel (dB) (in the Acoustics ... categor y) is the Acoustic P ower per unit ar ea gener ated b y boundar y layer turbulenc e, and r epresen ted in dB (see Equa tion 15.35 in the Theor y Guide ). It is a vailable only when the Broadband Noise S our ces acoustics mo del is b eing used . Surface Clust er ID (in the Radia tion... categor y) is used t o view the distr ibution of sur face clust ers in the domain. Each clust er has a unique in teger numb er (ID) asso ciated with it. Surface Corrosion R ate of species-n (in the Species ... categor y) is the r ate of th solid sp ecies c onsumption/dep osition. A p ositiv e value indic ates corrosion of the solid sp ecies on the in terface, and a nega tive value indic ates dep osition of the solid sp ecies . Surface Coverage of species-n (in the Species ... categor y) is the amoun t of a sur face sp ecies tha t is dep osited on the substr ate at a sp e- cific p oint in time . Surface Deposition R ate of species-n (in the Species ... categor y) is the amoun t of a sur face sp ecies tha t is dep osited on the substr ate. Its unit quan tity is mass-flux . Surface dp dt RMS, definition (in the Acoustics ... categor y) is the RMS v alue of the time-der ivative of sta tic pr essur e ( ). It is available when the Ffowcs-W illiams & H awkings acoustics mo del is b eing used . Surface Heat Transf er C oef. (in the Wall F luxes... categor y), as defined in ANSY S Fluen t, is giv en b y the equa tion (42.39) is the r eference temp erature defined in the Reference Values Task P age (p.3601 ). Note tha t is a c onstan t value tha t should b e represen tative of the pr oblem. Its unit quan tity is the hea t- transf er- coefficien t. 3029Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Alphab etical Listing of F ield Variables and Their D efinitionsSurface Inciden t Radia tion (in the Wall F luxes... categor y) is the net inc oming r adia tion hea t flux on a sur face. Its unit quan tity is hea t-flux . Surface Nusselt N umb er (in the Wall F luxes... categor y) is a lo cal nondimensional c oefficien t of hea t transf er defined b y the equa tion (42.40) Surface Stanton N umb er (in the Wall F luxes... categor y) is a nondimensional c oefficien t of hea t transf er defined b y the equa tion (42.41) are reference values of densit y and v elocity defined in the Reference Values Task P age (p.3601 ), and is the sp ecific hea t at constan t pressur e. Swirl Pull Velocity (in the Solidific ation/M elting ... categor y) is the tangen tial-dir ection c omp onen t of the pull v elocity for the solid ma terial in a c ontinuous c asting pr ocess. Its unit quan tity is velocity. Swirl Velocity (in the Velocity... categor y) is the tangen tial-dir ection c omp onen t of the v elocity in an axisymmetr ic swir ling flo w. See Velocity Reporting Options (p.2961 ) for details .The unit quan tity for Swirl Velocity is velocity. For multiphase mo dels , this v alue c orresponds t o the selec ted phase in the Phase drop-do wn list. Swirl-Wall S hear S tress (in the Wall F luxes... categor y) is the swir l comp onen t of the f orce ac ting tangen tial t o the sur face due t o friction. Its unit quan tity is pressur e. Tangen tial Velocity (in the Velocity... categor y) is the v elocity comp onen t in the tangen tial dir ection. (See Velocity Reporting Options (p.2961 ) for details .) The unit quan tity for Tangen tial Velocity is velocity. Temp erature... indic ates the quan tities asso ciated with the ther modynamic t emp erature of a ma terial. Thermal C onduc tivit y (in the Properties ... categor y) is a par amet er ( ) tha t defines the c onduc tion r ate thr ough a ma terial via Fourier’s law ( ). A lar ge ther mal c onduc tivit y is asso ciated with a go od hea t conduc tor and a small ther mal c onduc tivit y with a p oor hea t conduc tor (go od insula tor). Its unit quan tity is ther mal-c on- duc tivit y. Note tha t when p ostpr ocessing solid ma terial pr operties, the Thermal C onduc tivit y will b e dis- played as z ero if an anisotr opic ther mal c onduc tivit y mo del is b eing used f or a solid ma terial. Thermal D iff C oef of species-n (in the Species ... categor y) is the ther mal diffusion c oefficien t for the th species ( in Equa- tion 8.68 (p.1141 ),Equa tion 8.70 (p.1142 ), and Equa tion 8.74 (p.1143 )). Its unit quan tity is visc osit y. Time S tep (in the Residuals ... categor y) is the lo cal time st ep of the c ell, , at the cur rent iteration le vel. Its unit quan tity is time . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3030Field F unction D efinitionsTime S tep Sc ale (in the Species ... categor y) is the fac tor b y which the time st ep is r educ ed f or the stiff chemistr y solv er (available in the densit y-based solv er only). The time st ep is sc aled do wn based on an eigen value and positivit y analy sis. Total E chem H eat Sour ce (in the Potential... categor y) is the summa tion of the J oule and F aradaic hea t sour ces.The t otal hea t sour ce due t o elec trochemic al chemic al reactions is added t o the ener gy equa tion. Total E nergy (in the Temp erature... categor y) is the t otal ener gy per unit mass . Its unit quan tity is specific-ener gy. For all sp ecies mo dels , plots of Total E nergy include the sensible , chemic al and k inetic ener gies . For multiphase models , this v alue c orresponds t o the selec ted phase in the Phase drop-do wn list. Total E nthalp y (in the Temp erature... categor y) is defined as wher e is the Enthalp y, as defined in Equa tion 5.7 in the Theor y Guide , and is the v elocity magnitude . Its unit quan tity is specific-ener gy. For all sp ecies models , plots of Total E nthalp y consist of the sensible , chemic al and k inetic ener gies . For multiphase models , this v alue c orresponds t o the selec ted phase in the Phase drop-do wn list. Total E nthalp y Deviation (in the Temp erature... categor y) is the diff erence between Total E nthalp y and the r eference en thalp y, , wher e is the r eference en thalp y defined in the Reference Values Task P age (p.3601 ). However, for non-pr emix ed and par tially pr emix ed mo dels ,Total E nthalp y Deviation is the diff erence between Total E nthalp y and t otal adiaba tic en thalp y (total en thalp y wher e no hea t loss or gain o ccurs). The unit quan tity for Total E nthalp y Deviation is specific-ener gy. For multiphase mo dels , this v alue corresponds t o the selec ted phase in the Phase drop-do wn list. Total P ressur e (in the Pressur e... categor y) is the pr essur e at the ther modynamic sta te tha t would e xist if the fluid w ere brough t to zero velocity and z ero potential. For compr essible flo ws, the t otal pr essur e is c omput ed using isen tropic r elationships . For constan t , this r educ es to: (42.42) For inc ompr essible flo ws (constan t densit y fluid), we use B ernoulli ’s equa tion, , wher e is the lo cal d ynamic pr essur e. Its unit quan tity is pressur e. Imp ortant Note tha t in the p ostpr ocessing , the t otal pr essur e is pr esen ted as gauge pr essur e, for c ompr essible and inc ompr essible flo ws. If the t otal absolut e pr essur e is needed , then add the v alue of the r eference pr essur e to the t otal gauge pr essur e. Total S urface Corrosion R ate (in the Potential... categor y) is the t otal r ate of solid sp ecies c onsumption/dep osition. A p ositiv e value indic ates c orrosion of the solid sp ecies on the in terface, and a nega tive value indic ates dep osition of the solid sp ecies . It’s comput ed as the sum of the sur face corrosion r ates (Surface Corrosion R ates of spe- cies-n reported under the Species categor y) of all sp ecies . 3031Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Alphab etical Listing of F ield Variables and Their D efinitionsTotal S urface Heat Flux (in the Wall F luxes... categor y) is the r ate of t otal hea t transf er thr ough the c ontrol sur face. It is c alcula ted by the solv er acc ording t o the b oundar y conditions b eing applied a t tha t sur face. By definition, hea t flux out of the domain is nega tive, and hea t flux in to the domain is p ositiv e.The unit quan tity for Total S urface Heat Flux is hea t-flux . Total Temp erature (in the Temp erature... categor y) is the t emp erature at the ther modynamic sta te tha t would e xist if the fluid w ere br ough t to zero velocity. For compr essible flo ws, the t otal t emp erature is c omput ed fr om the total en thalp y using the cur rent metho d (sp ecified in the Create/Edit M aterials D ialog Box (p.3386 )). For incompr essible flo ws, the t otal t emp erature is equal t o the sta tic t emp erature, unless k inetic ener gy is explicitly added .The unit quan tity for Total Temp erature is temp erature. Transmitt ed R adia tion F lux (B and-n) (in the Wall F luxes... categor y) is the amoun t of r adia tive hea t flux tr ansmitt ed b y a semi-tr anspar ent wall for a par ticular band of r adia tion. Its unit quan tity is hea t-flux . Transmitt ed Visible S olar F lux, Transmitt ed IR S olar F lux (in the Wall F luxes... categor y) is the amoun t of solar hea t flux tr ansmitt ed b y a semi-tr anspar ent wall or porous jump b oundar y for a visible or infr ared r adia tion. Turbulenc e... includes quan tities r elated t o turbulenc e. See Modeling Turbulenc e (p.1375 ) for inf ormation ab out the tur- bulenc e mo dels a vailable in ANSY S Fluen t. Turbulenc e In tensit y (in the Turbulenc e... categor y) is the r atio of the magnitude of the RMS turbulen t fluc tuations t o the r ef- erence velocity: (42.43) wher e is the turbulenc e kinetic ener gy and is the r eference velocity sp ecified in the Reference Values Task P age (p.3601 ).The r eference value sp ecified should b e the mean v elocity magnitude f or the flo w. Note tha t turbulenc e in tensit y can b e defined in diff erent ways, so y ou ma y want to use a cust om field func tion f or its definition. See Custom F ield F unctions (p.3038 ) for mor e inf ormation. Turbulen t Dissipa tion R ate (E psilon) (in the Turbulenc e... categor y) is the turbulen t dissipa tion r ate. Its unit quan tity is turbulen t-ener gy-diss- rate.This quan tity is a vailable f or the k-epsilon and k-omega based turbulenc e mo dels , wher e the epsi- lon/omega r elationship is defined as (42.44) For multiphase mo dels , this v alue c orresponds t o the selec ted phase in the Phase drop-do wn list. Turbulen t Flame S peed (in the Premix ed C ombustion... categor y) is the turbulen t flame sp eed c omput ed b y ANSY S Fluen t using Equa tion 9.8 in the Theor y Guide . Its unit quan tity is velocity. Turbulen t Kinetic E nergy (k) (in the Turbulenc e... categor y) is the turbulenc e kinetic ener gy per unit mass defined as (42.45) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3032Field F unction D efinitionsTurbulen t Rate of Reac tion-n (in the Reac tions ... categor y) is the r ate of pr ogress of the th reaction c omput ed b y Equa tion 7.25 or Equa tion 7.26 (in the Theor y Guide ). For the “edd y-dissipa tion ” mo del, the v alue is the same as the Rate of Reac tion-n . For the “finit e-rate” mo del, the v alue is z ero. Turbulen t Re ynolds N umb er (Re_y) (in the Turbulenc e... categor y) is a nondimensional quan tity defined as (42.46) wher e is turbulenc e kinetic ener gy, is the distanc e to the near est w all, and is the laminar viscosity. Turbulen t Visc osit y (in the Turbulenc e... categor y) is the turbulen t visc osity of the fluid c omput ed using the turbulenc e model. Its unit quan tity is visc osit y. For multiphase mo dels , this v alue c orresponds t o the selec ted phase in the Phase drop-do wn list. Additional inf ormation with r espect to the Emb edded LES (E-LES) mo del c an be found in Postpr ocessing f or Turbulen t Flows (p.1456 ). Turbulen t Visc osit y (lar ge-sc ale) (in the Turbulenc e... categor y) is used in the - - transition mo del.S ee Transp ort Equa tions f or the k- kl-ω Model in the Theor y Guide f or mor e details ( Equa tion 4.151 ). Turbulen t Visc osit y (small-sc ale) (in the Turbulenc e... categor y) is used in the - - transition mo del. See Transp ort Equa tions f or the k- kl-ω Model in the Theor y Guide f or mor e details ( Equa tion 4.145 ). Turbulen t Visc osit y Ratio (in the Turbulenc e... categor y) is the r atio of turbulen t visc osity to the laminar visc osity. Additional inf orm- ation with r espect to the Emb edded LES (E-LES) mo del c an b e found in Postpr ocessing f or Turbulen t Flows (p.1456 ). User M emor y (in the User D efined M emor y... categor y) is the v alue of the quan tity in the th user-defined memor y location. User N ode M emor y (in the User D efined M emor y... categor y) is the v alue of the quan tity in the th user-defined no de memor y location. Unbur nt Fuel M ass F raction (in the Premix ed C ombustion... categor y) is the mass fr action of unbur nt fuel. This func tion is a vailable only f or non-adiaba tic mo dels . Unstead y Statistics ... includes mean and r oot mean squar e error (RMSE) v alues of solution v ariables and cust om field func tions derived fr om tr ansien t flo w calcula tions . User D efined M emor y... includes quan tities tha t ha ve been allo cated t o a user-defined memor y location. See the separ ate Fluen t Customiza tion M anual for details ab out user-defined memor y. 3033Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Alphab etical Listing of F ield Variables and Their D efinitionsUser-D efined Sc alars ... includes quan tities r elated t o user-defined sc alars . See the separ ate Fluen t Customiza tion M anual for in- formation ab out using user-defined sc alars . UU Re ynolds S tress (in the Turbulenc e... categor y) is the stress. UV Re ynolds S tress (in the Turbulenc e... categor y) is the stress. Resolv ed UV Re ynolds S tress (in the Turbulenc e... categor y) is defined as: (42.47) at time .This v ariable is only a vailable if y ou enable Data S ampling f or Time S tatistics in the Run C alcula tion Task P age (p.3640 ).Time represen ts the time Data S ampling f or Time S tatistics is first enabled , which is not nec essar ily the first timest ep. UW Re ynolds S tress (in the Turbulenc e... categor y) is the stress. Resolv ed UW Re ynolds S tress (in the Turbulenc e... categor y) is defined as: (42.48) at time .This v ariable is only a vailable if y ou enable Data S ampling f or Time S tatistics in the Run C alcula tion Task P age (p.3640 ).Time represen ts the time Data S ampling f or Time S tatistics is first enabled , which is not nec essar ily the first timest ep. Varianc e of S pecies (in the NOx... categor y) is the v arianc e of the mass fr action of a selec ted sp ecies in the flo w field . It is c al- cula ted fr om Equa tion 14.113 in the Theor y Guide . Varianc e of S pecies 1, Varianc e of S pecies 2 (in the NOx... categor y) ar e the v arianc es of the mass fr actions of the selec ted sp ecies in the flo w field . They are each c alcula ted fr om Equa tion 14.113 in the Theor y Guide . Varianc e of Temp erature (in the NOx... categor y) is the v arianc e of the nor maliz ed t emp erature in the flo w field . It is c alcula ted fr om Equa tion 14.113 in the Theor y Guide . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3034Field F unction D efinitionsVelocity... includes the quan tities asso ciated with the r ate of change in p osition with time .The instan taneous v elocity of a par ticle is defined as the first der ivative of the p osition v ector with r espect to time , , termed the v elocity vector, . Velocity Angle (in the Velocity... categor y) is defined as f ollows: For a 2D mo del, (42.49) For a 2D or axisymmetr ic mo del, (42.50) For a 3D mo del, (42.51) Its unit quan tity is angle . Velocity M agnitude (in the Velocity... categor y) is the sp eed of the fluid . Its unit quan tity is velocity. For multiphase mo dels , this v alue c orresponds t o the selec ted phase in the Phase drop-do wn list. Volume fr action (in the Phases ... categor y) is the v olume fr action of the selec ted phase in the Phase drop-do wn list. Volumetr ic A bsorb ed R adia tion (in the Radia tion... categor y) is the spher ical mean absorb ed r adia tion and , for a single sp ectral band , can be defined as: (42.52) wher e is the r adia tion in tensit y and is the absor ption c oefficien t. Volumetr ic Emitt ed R adia tion (in the Radia tion... categor y) is the spher ical mean emitt ed r adia tion and , for a single sp ectral band , can be defined as . (42.53) wher e is the black body fraction, is the S tefan-B oltzmann c onstan t, is the t emp erature, and is the absor ption c oefficien t. Vorticit y M agnitude (in the Velocity... categor y) is the magnitude of the v orticit y vector.Vorticit y is a measur e of the r otation of a fluid elemen t as it mo ves in the flo w field , and is defined as the cur l of the v elocity vector: (42.54) VV Re ynolds S tress (in the Turbulenc e... categor y) is the stress. 3035Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Alphab etical Listing of F ield Variables and Their D efinitionsVW Re ynolds S tress (in the Turbulenc e... categor y) is the stress. Resolv ed VW Re ynolds S tress (in the Turbulenc e... categor y) is defined as: (42.55) at time .This v ariable is only a vailable if y ou enable Data S ampling f or Time S tatistics in the Run C alcula tion Task P age (p.3640 ).Time represen ts the time Data S ampling f or Time S tatistics is first enabled , which is not nec essar ily the first timest ep. Wall A djac ent Heat Transf er C oef. (in the Wall F luxes… categor y) is defined as: (42.56) wher e is the sur face hea t flux, is the w all fac e temp erature, and is the w all adjac ent cell temp erature. Wall A djac ent Temp erature (in the Temp erature… categor y) is the t emp erature of the fluid c ell adjac ent to the w all. Wall C overage (in the Wall F ilm… categor y) is the fr action of the w all sur face covered b y the w all film. Wall F ilm F ace Pressur e (in the Wall F ilm… categor y) is the fac e pr essur e of the w all film. Wall F ilm H eigh t (in the Wall F ilm… categor y) is the heigh t of the w all film. Wall F ilm H eat Flux (in the Wall F ilm… categor y) is the hea t flux of the w all film t o the w all. Wall F ilm Impingemen t Mass F lux (in the Wall F ilm… categor y) is the mass flux impinging on the w all film. Wall F ilm M ass (in the Wall F ilm… categor y) is the mass of the w all film (in units of mass). Wall F ilm Temp erature (in the Wall F ilm… categor y) is the t emp erature of the w all film. Wall F ilm Velocity M agnitude (in the Wall F ilm… categor y) is the v elocity magnitude of the w all film. Wall F ilm X-V elocity (in the Wall F ilm… categor y) is the x-c omp onen t of the v elocity of the w all film. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3036Field F unction D efinitionsWall F ilm Y-V elocity (in the Wall F ilm… categor y) is the y-c omp onen t of the v elocity of the w all film. Wall F ilm Z-V elocity (in the Wall F ilm… categor y) is the z-c omp onen t of the v elocity of the w all film. Wall F luxes... includes quan tities r elated t o forces and hea t transf er at wall sur faces. Wall F unc . Heat Tran. Coef. is gener ally defined b y the equa tion (42.57) wher e is the sp ecific hea t, is the near-w all turbulenc e velocity sc ale, is the visc ous hea ting (included only f or v ariable densit y flo ws,Equa tion 4.321 in the Fluent Theor y Guide ), is the dimen- sionless la w-of-the-w all t emp erature defined f or the standar d w all func tions in Equa tion 4.320 in the Fluent Theor y Guide . For the enhanc ed w all tr eatmen t, the c ombined f orms f or and (Equa tion 4.320 and Equa tion 4.321 in the Fluent Theor y Guide ) are replac ed b y the c orresponding func tions obtained using the blending of K ader , explained in Enhanc ed Wall Treatmen t for M omen tum and Ener gy Equa tions in the Fluent Theor y Guide . Wall Ir radia tion F lux.N ormaliz ed S td D eviation (in the Radia tion... categor y) is the sta tistic al standar d de viation f or the hemispher ical mean ir radia tion flux. Wall L eidenfr ost Temp erature (in the Wall F ilm… categor y) is the w all temp erature at which the insula ting v apor la yer fully c overs the hot w all pr eventing the liquid fr om b oiling r apidly . Film M ass F raction of material-i (in the Wall F ilm... categor y) is the mass fr action of the discr ete phase ma terial i in the w all film. (The name of the ma terial will r eplac e material-i in Film M ass F raction of material-i .) Wall S hear S tress (in the Wall F luxes... categor y) is the f orce ac ting tangen tial t o the sur face due t o friction. Its unit quan tity is pressur e. For multiphase mo dels , this v alue c orresponds Equa tion 4.321 in the Fluent Theor y Guide to the selec ted phase in the Phase drop-do wn list. Wall Temp erature (in the Temp erature... categor y) is the t emp erature on a sur face (including w all sur faces, shado w w all surfaces, and shell sur faces). For an illustr ation of such sur faces for thin w alls and shells , see Figur e 7.54: A Thin Wall (p.987) and Figur e 13.5: A B oundar y Wall with S hell C onduc tion (p.1482 ), respectively. Wall Temp erature (Thin) (in the Temp erature... categor y) is f or thin w alls only , and r eports the t emp erature on the sur face tha t is separ ated fr om the fluid / solid c ells b y the w all thick ness , as sho wn in Figur e 7.54: A Thin Wall (p.987). Note tha t the w all ther mal b oundar y conditions ar e applied on this sur face. Wall Yplus (in the Turbulenc e... categor y) is a nondimensional par amet er defined b y the equa tion (42.58) 3037Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Alphab etical Listing of F ield Variables and Their D efinitionswher e is the fr iction v elocity, is the distanc e from p oint to the w all, is the fluid densit y, and is the fluid visc osity at point . See Near-W all Treatmen ts for Wall-B ounded Turbulen t Flows in the Theor y Guide for details . For multiphase mo dels , this v alue c orresponds t o the selec ted phase in the Phase drop-do wn list. Wall Ystar (in the Turbulenc e... categor y) is a nondimensional par amet er defined b y the equa tion (42.59) wher e is the turbulenc e kinetic ener gy at point , is the distanc e from p oint to the w all, is the fluid densit y, and is the fluid visc osity at point . See Near-W all Treatmen ts for Wall- Bounded Turbulen t Flows in the Theor y Guide for details . WW Re ynolds S tress (in the Turbulenc e... categor y) is the stress. X-C oordina te,Y-C oordina te, Z-C oordina te (in the Mesh... categor y) ar e the C artesian c oordina tes in the -axis , -axis , and -axis dir ections r espectively. The unit quan tity for these v ariables is length . X D isplac emen t,Y D isplac emen t, Z D isplac emen t (in the Structure... categor y) ar e the c omp onen ts of the displac emen t.These v ariables ar e intended only for solid z ones and/or their adjac ent walls in in trinsic fluid-str ucture interaction (FSI) simula tions . X Face Area,Y Face Area, Z F ace Area (in the Mesh... categor y) ar e the c omp onen ts of the fac e area v ector for nonin ternal fac es (tha t is, faces that only ha ve c0 and no c1).The v alues ar e stored on the fac e itself and used when r equir ed.These variables ar e intended only f or zone sur faces and not f or other sur faces cr eated f or p ostpr ocessing . X Pull Velocity,Y Pull Velocity, Z P ull Velocity (in the Solidific ation/M elting ... categor y) ar e the , , and comp onen ts of the pull v elocity for the solid material in a c ontinuous c asting pr ocess.The unit quan tity for each is velocity. X Velocity,Y Velocity, Z Velocity (in the Velocity... categor y) ar e the c omp onen ts of the v elocity vector in the -axis , -axis , and -axis directions , respectively.The unit quan tity for these v ariables is velocity. For multiphase mo dels , these values c orrespond t o the selec ted phase in the Phase drop-do wn list. X-V orticit y,Y-V orticit y, Z-V orticit y (in the Velocity... categor y) ar e the , , and comp onen ts of the v orticit y vector. X-W all S hear S tress,Y-W all S hear S tress, Z-W all S hear S tress (in the Wall F luxes... categor y) ar e the , , and comp onen ts of the f orce ac ting tangen tial t o the sur face due t o friction. The unit quan tity for these v ariables is pressur e. For multiphase mo dels , these v alues c or- respond t o the selec ted phase in the Phase drop-do wn list. 42.5. Custom F ield F unc tions In addition t o the basic field v ariables pr ovided b y ANSY S Fluen t (and descr ibed in Alphab etical Listing of F ield Variables and Their D efinitions (p.2988 )), you c an also define y our o wn field func tions t o be used Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3038Field F unction D efinitionsin conjunc tion with an y of the c ommands tha t use these v ariables (c ontour and v ector displa y, XY plots , and so on). This c apabilit y is a vailable with the Custom F ield F unction C alcula tor D ialog Box (p.3797 ). You c an use the default field v ariables , previously defined c alcula tor func tions , and c alcula tor op erators to cr eate new func tions . (Several sample func tions ar e descr ibed in Sample C ustom F ield F unc- tions (p.3043 ).) Any field func tions tha t you define will b e sa ved in the c ase file the ne xt time tha t you sa ve it. You c an also sa ve your cust om field func tions t o a separ ate file (as descr ibed in Manipula ting , Saving , and Loading C ustom F ield F unctions (p.3042 )), so tha t the y can b e used with a diff erent case file . Imp ortant Note tha t all cust om field func tions ar e evalua ted and st ored in SI units . Any solv er-defined flo w variables tha t you use in y our field-func tion definition will b e aut o- matically c onverted if the y are not alr eady in SI units , but y ou must b e careful t o en ter con- stan ts in the appr opriate units . Note also tha t explicit no de v alues ar e not a vailable f or cust om field func tions; all no de v alues f or these func tions will b e comput ed b y averaging the v alues in the sur rounding c ells, as descr ibed in Node Values (p.2960 ). For additional inf ormation, see the f ollowing sec tions: 42.5.1. Creating a C ustom F ield F unction 42.5.2. Manipula ting , Saving , and L oading C ustom F ield F unctions 42.5.3. Sample C ustom F ield F unctions 42.5.1. Creating a C ustom F ield F unc tion To cr eate your o wn field func tion, you will use the Custom F ield F unction C alcula tor D ialog Box (p.3797 ) (Figur e 42.3: The C ustom F ield F unction C alcula tor D ialog Box (p.3040 )).This dialo g box allo ws you t o define field func tions based on e xisting func tions , using simple c alcula tor op erators. Any func tions that you define will b e added t o the list of default flo w variables and other field func tions pr ovided by the solv er. Paramet ers & C ustomiza tion → Custom F ield F unc tions New... Imp ortant Recall tha t you must en ter all c onstan ts in the func tion definition in SI units . 3039Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Custom F ield F unctionsFigur e 42.3: The C ustom F ield F unc tion C alcula tor D ialo g Box The st eps f or cr eating a cust om field func tion ar e as f ollows: 1.Use the c alcula tor butt ons and the Field F unc tions list and Selec t butt on t o sp ecify the func tion definition, as descr ibed b elow. (As you selec t each it em fr om the Field F unc tions list or click a butt on in the c alcu- lator k eypad , its symb ol will app ear in the Definition text en try box.You cannot edit the c ontents of this box dir ectly; if you w ant to delet e par t of a func tion, use the DEL butt on on the k eypad .) Imp ortant The r ange of in tegers and r eal numb ers tha t can b e stored is as f ollows: Note tha t using a numb er less than 1e-39 ma y pr oduce inaccur ate results , while v alues less than 1e-45 will pr oduce a r esult of z ero. 2.Specify the name of the func tion in the New Func tion N ame field . Imp ortant Be sur e tha t you do not sp ecify a name tha t is alr eady used f or a standar d field func tion (for e xample ,velocity-magnitude ); you c an see a c omplet e list of the pr edefined field func tions in ANSY S Fluen t by selec ting the display/contours text command and viewing the a vailable choic es for contours of . 3.Click the Define butt on. When y ou click Define , the solv er will cr eate the func tion and add it t o the list of Custom F ield Func tions within the dr op-do wn list of a vailable field func tions .The Define push butt on is gr ayed out after y ou cr eate a new func tion or if the Definition text en try box is empt y. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3040Field F unction D efinitionsShould y ou decide t o rename or delet e the func tion af ter y ou ha ve complet ed the definition, you c an do so in the Field F unction D efinitions D ialog Box (p.3823 ), which y ou c an op en b y click ing on the Manage ... push butt on. See Manipula ting , Saving , and L oading C ustom F ield F unctions (p.3042 ) for details . 42.5.1.1. Using the C alculat or Butt ons Your func tion definition c an include man y basic c alcula tor op erations (f or e xample , addition, subtr ac- tion, multiplic ation, squar e root).When y ou selec t a c alcula tor butt on (b y click ing on it), the appr opriate symb ol will app ear in the Definition text en try box.The meaning of the butt ons is str aigh tforward; they are similar t o the butt ons y ou w ould find on an y standar d calcula tor.You should , however, not e the f ollowing: •The CE/C butt on will clear the en tire Definition and the New Func tion N ame , if you ha ve en tered one . The DEL butt on will delet e only the last en try in the Definition text en try box.You c an use DEL to delet e char acters one a t a time , star ting with the last one en tered. •To obtain the in verse tr igonometr ic func tions ar csin, arccos, and ar ctan, click the INV butt on b efore se- lecting sin,cos, or tan. •The ABS butt on yields the absolut e value of the numb er tha t follows it. Likewise , the ln butt on yields the natural lo garithm of the numb er tha t follows it, and the log10 butt on yields the base 10 lo garithm func tion of the numb er tha t follows it. Imp ortant log10 and ln will b e calcula ted f or v alues gr eater than 0. For v alues less than or equal to 0, the r esultan t value will b e zero. •The PI butt on r epresen ts and the e butt on r epresen ts the base of the na tural lo garithm sy stem (which is appr oxima tely equal t o ). 42.5.1.2. Using the F ield F unc tions List Your func tion definition c an include an y of the field func tions defined b y the solv er (and list ed in Alphab etical Listing of F ield Variables and Their D efinitions (p.2988 )) or b y you.You c an also use an y report definitions tha t you ha ve created (see Monit oring and R eporting S olution D ata (p.2910 ) for ad- ditional inf ormation). To include one of these v ariables/func tions in y our func tion definition, selec t it in the Field F unc tions drop-do wn list and then click the Selec t butt on b elow the list. The symb ol for the selec ted it em will app ear in the Definition text en try box (for e xample ,p will app ear if y ou selec t Static P ressur e). Note If a cust om field func tion definition uses a r eport definition, then it c annot b e exported to a file . 3041Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Custom F ield F unctions42.5.2. Manipula ting , Saving , and L oading C ustom F ield F unc tions Onc e you ha ve defined y our field func tions , you c an manipula te them using the Field F unction Definitions D ialog Box (p.3823 ) (Figur e 42.4: The F ield F unction D efinitions D ialog Box (p.3042 )).You c an displa y a func tion definition t o be sur e tha t it is c orrect, delet e the func tion if y ou decide tha t it is in- correct and must b e redefined , or giv e the func tion a new name .You c an also sa ve cust om field func tions t o a file or r ead them fr om a file .The cust om field func tion file allo ws you t o transf er y our cust om func tions b etween c ase files . To op en the Field F unction D efinitions D ialog Box (p.3823 ), right-click Custom F ield F unc tions (under the Paramet ers & C ustomiza tion branch of the tr ee) and selec t Manage ....You c an also click the Manage ... butt on in the Custom F ield F unction C alcula tor D ialog Box (p.3797 ). To op en the Field F unction D efinitions D ialog Box (p.3823 ), right-click Custom F ield F unc tions (under the Paramet ers & C ustomiza tion branch of the tr ee) and selec t Manage ....You c an also click the Manage ... butt on in the Custom F ield F unction C alcula tor D ialog Box (p.3797 ). Figur e 42.4: The F ield F unc tion D efinitions D ialo g Box The f ollowing ac tions c an b e performed in the Field F unction D efinitions D ialog Box (p.3823 ): •To check the definition of a func tion, selec t it in the Field F unc tions list. Its definition will b e displa yed in the Definition field .This displa y is f or inf ormational pur poses only ; you c annot edit it. If you w ant to change a func tion definition, you must delet e the func tion and define it again in the Custom F ield F unction C alcu- lator D ialog Box (p.3797 ). •To delet e a func tion, selec t it in the Field F unc tions list and click the Delet e butt on. •To rename a func tion, selec t it in the Field F unc tions list, enter a new name in the Name field , and click the Rename butt on. Imp ortant Be sur e tha t you do not sp ecify a name tha t is alr eady used f or a standar d field func tion (for e xample ,velocity-magnitude ); you c an see a c omplet e list of the pr edefined Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3042Field F unction D efinitionsfield func tions in ANSY S Fluen t by selec ting the display/contours text command and viewing the a vailable choic es for contours of . •To sa ve all of the func tions in the Field F unc tions list t o a file , click the Save... butt on and sp ecify the file name in The S elec t File D ialog Box (p.569). •To read cust om field func tions fr om a file tha t you sa ved as descr ibed ab ove, click the Load ... butt on and specify the file name in the r esulting Selec t File dialo g box. (Custom field func tion files ar e valid Scheme func tions , and c an also b e loaded with the File/Read/Scheme ... ribbon tab it em, as descr ibed in Reading Scheme S ource Files (p.597).) 42.5.3. Sample C ustom F ield F unc tions When y ou ar e check ing the r esults of y our simula tion, you ma y find it useful t o define some of the following field func tions: •To define a func tion tha t det ermines the r atio of sta tic pr essur e to inlet t otal pr essur e, use the r elationship (42.60) wher e is the sta tic pr essur e calcula ted b y the solv er, is the inlet t otal pr essur e, and is the operating pr essur e for the pr oblem. Use the solv er-defined func tion Static P ressur e for , and the numer ical value tha t you sp ecified f or Gauge Total P ressur e in the Pressur e Inlet D ialog Box (p.3524 ) for . Specify the v alue of the op erating pr essur e to be the v alue tha t you set in the Operating Conditions D ialog Box (p.3470 ). As discussed in Operating P ressur e (p.1152 ), all pr essur es in ANSY S Fluen t are gauge pr essur es relative to the op erating pr essur e. If the op erating pr essur e is z ero, as is gener ally the c ase f or c ompr essible flo w calcula tions , the e xpression f or the pr essur e ratio r educ es to (42.61) •To define a func tion tha t det ermines the cr itical velocity ratio , a par amet er tha t is sometimes used in turb omachiner y calcula tions , use the r elationship (42.62) In this r elationship , is the cr itical velocity (tha t is, the v elocity tha t would o ccur f or the same stagna tion c onditions if ), is the r atio of sp ecific hea ts, and is the pr essur e ratio defined in Equa tion 42.61 (p.3043 ) for which y ou cr eated y our o wn func tion. For , ratio of sp ecific hea ts, selec t Specific H eat Ratio (gamma) in the Properties ... categor y.To include , selec t Custom F ield Func tions ... in the first dr op-do wn list under Field F unc tions , and then selec t from the sec ond list the func tion name tha t you assigned . •Supp ose y ou ha ve swir ling flo w in a pip e, aligned with the axis , and y ou w ant to calcula te the flo w rate of angular momen tum thr ough a cr oss-sec tional plane: (42.63) 3043Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Custom F ield F unctionsYou c an cr eate a func tion f or the pr oduc t , wher e is the Radial C oordina te and is the Tangen tial Velocity.Then use the Surface In tegrals D ialog Box (p.3726 ) to comput e the flo w rate of this quan tity. Imp ortant The cust om field func tion c ontaining mo del dep enden t func tions (lik e temp erature when the ener gy equa tion is enabled) will b e comput ed only when those mo dels ar e still ac tive. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3044Field F unction D efinitionsChapt er 43: Parallel P rocessing The f ollowing sec tions descr ibe the par allel-pr ocessing f eatures of ANSY S Fluen t. 43.1. Introduction t o Parallel P rocessing 43.2. Starting P arallel ANSY S Fluen t Using F luen t Launcher 43.3. Starting P arallel ANSY S Fluen t on a Windo ws System 43.4. Starting P arallel ANSY S Fluen t on a Linux S ystem 43.5. Mesh P artitioning and L oad B alancing 43.6. Using G ener al Purpose G raphics P rocessing U nits (GPGPU s) With the A lgebr aic M ultigr id (AMG) S olver 43.7. Controlling the Threads 43.8. Check ing N etwork Connec tivit y 43.9. Check ing and Impr oving P arallel P erformanc e 43.1. Introduc tion t o Parallel P rocessing Processing in ANSY S Fluen t involves an in teraction b etween ANSY S Fluen t, a host pr ocess, and one or mor e comput e-no de pr ocesses . ANSY S Fluen t interacts with the host pr ocess and the c omput e no de(s) using a utilit y called cortex tha t manages ANSY S Fluen t’s user in terface and basic gr aphic al func tions . 3045Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Figur e 43.1: ANSY S Fluen t Archit ecture For ser ial pr ocessing , the ANSY S Fluen t solv er uses only a single c omput e no de. For par allel pr ocessing , a solution is c omput ed using multiple c omput e no des tha t ma y be executing on the same c omput er, or on diff erent comput ers in a net work (Figur e 43.1: ANSY S Fluen t Architecture (p.3046 )). Parallel ANSY S Fluen t splits up the mesh and da ta in to multiple par titions , then assigns each mesh partition t o a diff erent comput e no de.The numb er of par titions is equal t o or less than the numb er of processors (or c ores) a vailable on y our c omput e clust er.The c omput e-no de pr ocesses c an b e execut ed on a massiv ely par allel c omput er, a multiple-CPU w orksta tion, or a net work clust er of c omput ers. Gener ally, as the numb er of c omput e no des incr eases , turnaround time f or solutions will decr ease .This is referred t o as solv er “scalabilit y.” However, beyond a c ertain p oint, the r atio of net work communic ation to computa tion incr eases , leading t o reduc ed par allel efficienc y, so optimal sy stem sizing is imp ortant for simula tions . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3046Parallel P rocessingANSY S Fluen t uses a host pr ocess tha t do es not st ore an y mesh or solution da ta. Inst ead, the host process only in terprets c ommands fr om ANSY S Fluen t’s graphics-r elated in terface,cortex . The host distr ibut es those c ommands t o the other c omput e no des via a so cket in terconnec t to a single designa ted c omput e no de c alled compute-node-0 .This sp ecializ ed c omput e no de distr ibut es the host c ommands t o an y additional c omput e no des. Each c omput e no de simultaneously e xecut es the same pr ogram on its o wn da ta set. Communic ation fr om the c omput e no des t o the host is p ossible only thr ough compute-node-0 and only when all c omput e no des ha ve synchr oniz ed with each other . Each c omput e no de is vir tually c onnec ted t o every other c omput e no de, and r elies on in ter-pr ocess communic ation t o perform such func tions as sending and r eceiving ar rays, synchr onizing , and p erforming global op erations (such as summa tions o ver all c ells). Inter-pr ocess c ommunic ation is managed b y a message-passing libr ary. For e xample , the message-passing libr ary could b e a v endor implemen tation of the M essage P assing In terface (MPI) standar d, as depic ted in Figur e 43.1: ANSY S Fluen t Architec- ture (p.3046 ). All of the par allel ANSY S Fluen t processes (as w ell as the ser ial pr ocess) ar e iden tified b y a unique in teger ID.The host c ollec ts messages fr om compute-node-0 and p erforms op erations (such as pr inting , displa ying messages , and wr iting t o a file) on all of the da ta. For additional inf ormation, see the f ollowing sec tion: 43.1.1. Recommended U sage of P arallel ANSY S Fluen t 43.1.1. Rec ommended U sage of P arallel ANSY S Fluen t The r ecommended pr ocedur e for using par allel ANSY S Fluen t is as f ollows: 1.Start up the par allel solv er. For details , see Starting P arallel ANSY S Fluen t on a Windo ws System (p.3058 ) and Starting P arallel ANSY S Fluen t on a Linux S ystem (p.3063 ). 2.Read y our c ase file and ha ve ANSY S Fluen t par tition the mesh aut oma tically up on loading it. 3.Review the par titions and p erform par titioning again, if nec essar y. See Check ing the P artitions (p.3089 ) for details on check ing y our par titions . Note tha t ther e are other appr oaches f or par titioning , including manual par titioning in either the ser ial or the par allel solv er. For details , see Mesh P artitioning and L oad Balancing (p.3067 ). 4.Calcula te a solution. See Check ing and Impr oving P arallel P erformanc e (p.3096 ) for inf ormation on check ing and impr oving the par allel p erformanc e. Note Due t o limita tions imp osed b y se veral MPI implemen tations , ANSY S Fluen t performanc e on heterogeneous clust ers in volving either op erating sy stem or pr ocessor family diff erences may not b e optimal, and in c ertain c ases c ause failur es.You ar e ur ged t o use c aution in such par allel op erating en vironmen ts. 43.2. Starting P arallel ANSY S Fluen t Using F luen t Launcher Whether y ou star t ANSY S Fluen t either fr om the Linux or Windo ws command line with no ar gumen ts, from the Windo ws Programs menu , or fr om the Windo ws deskt op, Fluen t Launcher will app ear (f or 3047Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Starting P arallel ANSY S Fluen t Using F luen t Launcherdetails , see Starting ANSY S Fluen t Using F luen t Launcher (p.33) in the Getting S tarted G uide ), wher e you c an sp ecify the dimensionalit y of the pr oblem (2D or 3D), as w ell as other options (f or e xample , whether y ou w ant a single-pr ecision or double-pr ecision c alcula tion). Parallel c alcula tion options c an b e set up b y selec ting Parallel under Processing Options in F luen t Launcher . Onc e you selec t the Parallel option, you c an also sp ecify the numb er of pr ocesses using the Processes field under Solver. If your machines ar e equipp ed with appr opriate Gener al Purpose G raphic al Processing U nits (GPGPU s) you c an indic ate tha t these should b e used f or AMG solv er acc eleration b y setting the GPGPU s per Machine option. Note tha t the numb er of solv er pr ocesses p er machine must b e the same f or all ma- chines and tha t the numb er of pr ocesses p er machine must b e evenly divisible in to the v alue y ou sp ecify for GPGPU s per M achine .That is, for npr ocs solv er pr ocesses r unning on M machines using ngpgpus GPGPUS p er machine: Table 43.1: Examples f or GPGPU s per M achine (p.3048 ) presen ts se veral examples illustr ating the r elation- ship b etween numb er of machines , numb er of solv er pr ocesses , and GPGPU s per machine . Table 43.1: Examples f or GPGPU s per M achine Example 3 Example 2 Example 1 4 4 1 Numb er of M achines (M) 22 12 4 Numb er of S olver P rocesses (nprocs ) ngpgpus will b e ignor ed and GPGPU acc eleration will b e1, 3 1, 2, 4 Valid v alues f or GPGPU s per M achine (ngpgpus ) disabled (M does not e venly divide nprocs ) See Using G ener al Purpose G raphics P rocessing U nits (GPGPU s) With the A lgebr aic M ultigr id (AMG) Solver (p.3093 ) for mor e inf ormation ab out using GPGPU acc eleration. Activating the Parallel option enables the Parallel S ettings tab (visible when y ou selec t the Show More Options butt on). The Parallel S ettings tab allo ws you t o sp ecify settings f or running ANSY S Fluen t in par allel. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3048Parallel P rocessingFigur e 43.2: The P arallel S ettings Tab of F luen t Launcher •Specify the in terconnec t in the Interconnec ts drop-do wn list. The default setting is r ecommended . For a symmetr ic multi-pr ocessor (SMP) sy stem, the default setting uses shar ed memor y for communic ation. On Windo ws, the b est a vailable in terconnec t is aut oma tically used . (Linux only) I f you pr efer to selec t a sp ecific in terconnec t, you c an cho ose either ether net or infini- band . For mor e inf ormation ab out these in terconnec ts, see Table 43.5: Supp orted In terconnec ts for Linux P latforms (P er P latform) (p.3065 ),Table 43.6: Available MPI s for Linux P latforms (p.3066 ), and Table 43.7: Supp orted MPI s for Linux A rchitectures (P er In terconnec t) (p.3066 ). 3049Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Starting P arallel ANSY S Fluen t Using F luen t Launcher•Specify the t ype of message passing in terface (MPI) y ou r equir e for the par allel c omputa tions in the MPI Types field .The list of MPI t ypes v aries dep ending on the selec ted r elease and the selec ted ar chitecture. There are se veral options , based on the op erating sy stem of the par allel clust er. For mor e inf ormation ab out the a vailable MPI t ypes, see Table 43.2: Supp orted In terconnec ts for the Windo ws Platform (p.3060 ) - Table 43.3: Available MPI s for Windo ws Platforms (p.3060 ). Imp ortant It is y our r esponsibilit y to mak e sur e the in terconnec ts and the MPI t ypes ar e compa tible . If inc ompa tible inputs ar e used , Fluen t Launcher r esor ts to using the default v alues . •(Linux Only) S pecify either RSH (remot e shell clien t) or SSH (secur e shell clien t) under Remot e Spawn Command . For mor e inf ormation ab out setting up y our r emot e shell clien ts and secur e shell clien ts, see Setting U p Your R emot e Shell and S ecur e Shell C lients (p.3066 ). •Specify the t ype of par allel c alcula tion under Run Types: –Selec t Shared M emor y on L ocal M achine if the par allel c alcula tions ar e performed b y shar ing memor y allocations on y our lo cal machine . –Selec t Distribut ed M emor y on a C lust er if the par allel c alcula tions will b e distr ibut ed among several machines . You c an selec t Machine N ames and en ter the machine names dir ectly in to the t ext field as a list. Machine names c an b e separ ated either b y a c omma or a spac e.This is not r ecommended f or a long list of machine names . Alternatively, you c an selec t File C ontaining M achine N ames to sp ecify a hosts file (a file tha t contains the machine names), or y ou c an use the butt on t o br owse for a hosts file . To edit an e xisting hosts file , click the butt on. By default , Fluen t allo cates ranks t o machines in c ontiguous blo cks, wher e the blo ck siz es ar e as equal as p ossible .You c an c ontrol the p er machine blo ck allo cation siz e using the machine X: Y convention in the hosts sp ecific ation, wher e Y is the pr ocess blo ck c oun t for machine X.The process assignmen t will c ycle thr ough the machine list un til all pr ocesses ar e allo cated in sp ecified blocks. A fully r ound-r obin assignmen t of pr ocesses c an b e achie ved b y setting the machine blo ck allocation siz es to 1 (f or e xample ,machine1:1 ,machine2:1 , and so on). •Enable the Selec t IP In terface option and mak e a selec tion fr om the dr op-do wn list tha t app ears if you w ould lik e to sp ecify the IP in terface to be used b y the host pr ocess.This is equiv alen t to the -host_ip=host:ip command line option. An example of when y ou migh t use this option is when you ar e using distr ibut ed memor y on multiple machines and y our secur ity sof tware is dr opping the active so cket connec tions used b y ANSY S Fluen t (resulting in the f ollowing message in the c onsole: The fl process could not be started. ); while it is pr eferable t o avoid this b y creating an e xception f or ANSY S Fluen t in y our secur ity sof tware, you c ould inst ead selec t a suitable IP in terface. •For certain pla tforms, selec t Use J ob Scheduler under Options if the par allel c alcula tions ar e to be performed using a designa ted J ob Scheduler (f or details , see Setting P arallel Scheduler Options in F luen t Launch- er (p.3051 )).This also enables the Scheduler tab of F luen t Launcher . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3050Parallel P rocessingFor additional inf ormation, see the f ollowing sec tions: 43.2.1. Setting P arallel Scheduler Options in F luen t Launcher 43.2.2. Setting A dditional Options When R unning on R emot e Linux M achines 43.2.1. Setting P arallel Scheduler Options in F luen t Launcher Activating the Use J ob Scheduler option under Options in F luen t Launcher enables the Scheduler tab (visible when y ou selec t Show M ore Options ).The Scheduler tab allo ws you t o sp ecify settings for running ANSY S Fluen t with v arious job schedulers (f or e xample , the M icrosof t Job Scheduler f or Windo ws, or LSF , SGE , and PBS P rofessional on Linux). 3051Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Starting P arallel ANSY S Fluen t Using F luen t LauncherFigur e 43.3: The Scheduler Tab of F luen t Launcher ( Windo ws 64 Version) For Windo ws 64-bit , with MSMPI or when the Use Remot e Linux N odes option is selec ted, you c an specify tha t you w ant to use the J ob Scheduler b y selec ting the Use J ob Scheduler check b ox under Options in F luen t Launcher . Onc e selec ted, you c an then en ter a machine name in the Comput e Clust er H ead N ode N ame text field in the Scheduler tab . If you ar e running ANSY S Fluen t on the head no de, then y ou c an k eep the field empt y.This option tr ansla tes in to the pr oper par allel c ommand line syn tax f or using the M icrosof t Job Scheduler (f or details , see Starting P arallel ANSY S Fluen t with the M icrosof t Job Scheduler (p.3061 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3052Parallel P rocessingIf you w ant ANSY S Fluen t to star t after the nec essar y resour ces ha ve been allo cated b y the Scheduler , then selec t the Start When Resour ces ar e Available check b ox. For Linux, selec t the Use J ob Scheduler check b ox under Options to use one of thr ee a vailable job schedulers in the Scheduler tab . •Selec t Use LSF to use the LSF load managemen t system with or without check pointing . If you selec t Use Check pointing , then y ou c an sp ecify a check pointing dir ectory in the Check pointing D irectory field . By default , the cur rent working dir ectory is used . In addition, you c an sp ecify a numer ical value f or the fr equenc y of aut oma tic check pointing in the Automa tic C heck point with S etting of P eriod field . For mor e inf ormation, see Setting J ob Scheduler Options When R unning on R emot e Linux M a- chines (p.3057 ) or Part I: Running F luen t Under LSF . •Selec t Use SGE to use the SGE load managemen t system. You c an cho ose t o set v alues f or the SGE qmast er, as w ell as the SGE queue , or the SGE p e. Alternatively, you c an selec t Use SGE settings check box and sp ecify the lo cation and name of the SGE c onfigur ation file . For mor e inf ormation, see Setting J ob Scheduler Options When R unning on R emot e Linux M a- chines (p.3057 ) or Part III: Running F luen t Under SGE . •Selec t Use PBSP ro to use the PBS P rofessional load managemen t system. You c an cho ose t o set the v alue for PBS S ubmission H ost to sp ecify the PBS P rofessional submission host name f or submitting the job , if the machine y ou ar e using t o run the launcher c annot submit jobs t o PBS P rofessional. For mor e inf ormation, see Setting J ob Scheduler Options When R unning on R emot e Linux M a- chines (p.3057 ) or Part II: Running F luen t Under PBS P rofessional . If you e xperienc e poor gr aphics p erformanc e when using a job scheduler in Linux, you ma y be able to impr ove performanc e by changing the machine on which C ortex (the pr ocess tha t manages the graphic al user in terface and gr aphics) is r unning .The Graphics D ispla y M achine list pr ovides the following options: •Selec t First A llocated N ode if you w ant Cortex to run on the same machine as tha t used f or comput e no de 0. Note tha t it is p ossible t o enable a job-scheduler-supp orted na tive remot e no de acc ess mechanism in Linux when the gr aphics displa y machine is set t o First A llocated N ode.To do so , you must use the SCHEDULER_TIGHT_COUPLING=1 environmen t variable . For details ab out the MPI / job scheduler c ombina tions tha t are supp orted f or this tigh t coupling , see Running F luen t Using a L oad Manager . •Selec t Current Machine if you w ant Cortex to run on the same machine used t o star t Fluen t Launcher . •Selec t Specify M achine if you w ant Cortex to run on a sp ecified machine , which y ou selec t from the dr op- down list b elow. Imp ortant (Exceed onD emand Only) I f you selec t the Current Machine or Specify M achine , you must also set the CORTEX_PRE=ssrun environmen t variable t o sp ecify the ser ver side r ender ing to ensur e acc elerated gr aphics p erformanc e. 3053Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Starting P arallel ANSY S Fluen t Using F luen t LauncherFor e xample:CORTEX_PRE=/opt/Exceed_connection_server_13.8_64/bin/ss- run . Note tha t the pa th to ssrun ma y be diff erent for y our sp ecific en vironmen t. For Windo ws, you also ha ve the abilit y to run in ba tch mo de (using the Run in B atch M ode check box) when y ou pr ovide a jour nal file (designa ted in the Gener al Options tab) tha t exits ANSY S Fluen t at the end of the r un. For machines r unning M icrosof t HPC P ack 2008 or new er, you also ha ve the f ollowing options t o choose fr om: •Job Templa te allo ws you t o create a cust om submission p olicy to define the job par amet ers f or an applic ation. The clust er administr ator can use job t empla tes to manage job submission and optimiz e clust er usage . •Node G roup allo ws you t o sp ecify a c ollec tion of no des. Cluster administr ators c an cr eate gr oups and assign no des t o one or mor e gr oups . •Processor U nit allo ws you t o cho ose the f ollowing: –Core refers t o a single c omputing unit in a machine . For e xample , a quad-c ore pr ocessor has 4 c ores. –Socket refers t o a set of tigh tly in tegrated c ores as on a single chip . Machines of ten ha ve 2 or mor e sockets, each so cket with multiple c ores. A dual CPU, hexcore pr ocessor , for e xample , having a t otal of 12 c ores. –Node refers t o a named host , tha t is, a single machine used as par t of a clust er.Typic al clust ers range fr om a f ew t o tens, hundr eds, or sometimes thousands of machines . 43.2.2. Setting A dditional Options When R unning on Remot e Linux M achines The Remot e tab allo ws you t o sp ecify settings f or running ANSY S Fluen t par allel simula tions on Linux clust ers, via the Windo ws interface. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3054Parallel P rocessingFigur e 43.4: The Remot e Tab of F luen t Launcher You c an r un simula tions on Linux machines , either in ser ial or on par allel Linux clust ers, via the Windo ws interface.To acc ess r emot e 64-bit Linux clust ers f or y our par allel c alcula tion, selec t the Parallel (L ocal Machine) option under Processing Options (for details , see Setting P arallel Options in F luen t Launcher (p.39) in the Getting S tarted G uide ), then enable Use Remot e Linux N odes, which app ears under Options .The Remot e tab in F luen t Launcher will b ecome a vailable , wher e you c an sp ecify the remot e ANSY S Fluen t Linux installa tion r oot pa th in the Remot e Fluen t Ro ot P ath field .The Remot e Working D irectory field allo ws you t o sp ecify a w orking dir ectory for the r emot e Linux no des, other than the default temp directory. 3055Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Starting P arallel ANSY S Fluen t Using F luen t LauncherSelec t one of the f ollowing Remot e Spawn C ommands to connec t to the r emot e no de: •RSH will use RSH t o spa wn no des fr om the lo cal Windo ws machine t o the Linux head no de as w ell as fr om the Linux head no de t o the c omput e no des. If you w ant the Linux clust er to use SSH, then y ou must set the FLUENT_NO_REMOTE_RSH to 1.You also must set up passw ord-less acc ess. •SSH (the default) will use SSH t o spa wn no des fr om the lo cal Windo ws machine t o the Linux head no de as w ell as fr om the Linux head no de t o the c omput e no des.To use SSH with ANSY S Fluen t, you must set up passw ord-less SSH acc ess. If you w ant the Linux clust er to use RSH, then y ou must set the FLUENT_NO_RE- MOTE_SSH to 1. For mor e inf ormation ab out setting up SSH without a passw ord, see www .debian-admin- istration.or g/ar ticles/152. •Other allo ws you t o pr ovide other c ompa tible r emot e shell c ommands . Enable the Use Remot e Clust er H ead N ode field and sp ecify the r emot e no de t o which ANSY S Fluen t will c onnec t for spa wning (f or e xample , via rsh or ssh ). If this is not pr ovided , then ANSY S Fluen t will tr y to use the first machine in the machine file . If SGE is chosen as the job scheduler , then the SGE qmast er will ser ve the same pur pose. If PBS P rofessional is chosen as the job scheduler , then the host specified her e should b e the PBS P rofessional submission host. In addition t o using the settings in the Remot e tab in F luen t Launcher , the f ollowing c ommand line options ar e also a vailable when star ting ANSY S Fluen t from the c ommand line: -nodepath=path is the pa th on the r emot e machine wher e ANSY S Fluen t is installed . -node0=machine name is the machine fr om which t o launch other no des. -nodehomedir=directory is the dir ectory tha t becomes the cur rent working dir ectory for all the no des. Additionally , this will b e used as a scr atch ar ea for temp orary files tha t are created on the no des. -rsh=remote shell command is the c ommand tha t will b e used t o launch e xecutables r emot ely.This option defaults t o ssh.exe but can p oint to an y equiv alen t program. The form of this c ommand should b e tha t it should not w ait for additional inputs such as passw ords. For e xample , if you install SSH, and tr y to launch in mix ed mo de using ssh , the launch ma y fail unless y ou ha ve set up a lo gin f or SSH without a passw ord. For mor e in- formation ab out setting up SSH without a passw ord, see www .debian-administr ation.or g/ar ticles/152. As ther e ar e known issues with launching ANSY S Fluen t in mix ed Windo ws/Linux mo de fr om c ygwin, it is r ecommended tha t you use the c ommand pr ompt (cmd.exe ). When w orking with mix ed Linux and Windo ws runs tha t emplo y user-defined func tions (UDFs), not e the f ollowing: •The file tha t you ha ve op ened f or reading / wr iting on the host machine will not b e available on r emot e nodes and vic e-versa. You ma y ther efore ha ve to transf er da ta pr esen t on the no des t o the host and wr ite it from host , (or distr ibut e the da ta fr om the host t o the no des af ter reading the da ta fr om the host). •The loading of multiple UDF libr aries in to the same session is not supp orted. As a w orkaround , you c an compile multiple UDF files in to same UDF libr ary. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3056Parallel P rocessing43.2.2.1. Setting J ob Scheduler O ptions When R unning on R emot e Linux M achines By selec ting the Use Remot e Linux N odes option and the Use J ob Scheduler option in F luen t Launcher , you c an set job scheduler options f or the r emot e Linux machines y ou ar e acc essing f or your CFD analy sis. When these options ar e enabled in F luen t Launcher , you c an use the Scheduler tab t o set par amet ers for either LSF , SGE , or PBS P rofessional job schedulers .You c an lear n mor e ab out each of the schedulers by referring t o the L oad M anagemen t Documen tation. The f ollowing list descr ibes the v arious c ontrols tha t are available in the Scheduler tab: Use LSF allows you t o use the LSF job scheduler . LSF queue allows you t o sp ecify a job queue and en ter the queue name in the field . Use C heck pointing allows you t o use check pointing with LSF . By default , the check pointing dir ectory will b e the cur rent working dir ectory; however, you ha ve the option of enabling Check pointing D irectory. Check pointing D irectory allows you t o sp ecify a check pointing dir ectory tha t is diff erent from the cur rent working dir ectory. Automa tic C heck point with S etting of P eriod allows you t o sp ecify tha t the check pointing is done aut oma tically a t a set time in terval. Enter the period (in minut es) in the field , other wise check pointing will not o ccur unless y ou c all the bchkpnt command . Use SGE allows you t o use the SGE job scheduler . SGE qmast er is the machine in the SGE job submission host list. SGE will allo w the SGE qmast er node t o summon jobs . By default ,localhost is sp ecified f or SGE qmast er. Note tha t the butt on allo ws you t o check the job sta tus. SGE queue is the queue wher e you w ant to submit y our ANSY S Fluen t jobs . Note tha t you c an use the butt on t o contact the SGE qmast er for a list of queues . Leave this field blank if y ou w ant to use the default queue . SGE p e is the par allel en vironmen t wher e you w ant to submit y our ANSY S Fluen t jobs .The par allel en viron- men t must b e defined b y an administr ator. For mor e inf ormation ab out cr eating a par allel en viron- men t, refer to the SGE do cumen tation. Leave this field blank if y ou w ant to use the default par allel environmen t. 3057Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Starting P arallel ANSY S Fluen t Using F luen t LauncherUse PBSP ro allows you t o use the PBS P rofessional job scheduler . Imp ortant While r unning on r emot e Linux machines using an y one of the J ob Scheduler options , if the submitt ed job is in the job queue b ecause of una vailable r equest ed r esour ces, then the ANSY S Fluen t graphic al user in terface will r emain op en un til resour ces ar e available and the job star ts running . Note If you e xperienc e poor gr aphics p erformanc e when using a job scheduler in Linux, you may be able t o impr ove performanc e by sp ecifying tha t Cortex run on a sp ecified machine when y ou star t Fluen t.This c an b e done b y using the -gui_machine= and -scheduler= command line options (see Graphics Options (p.49) and Scheduler Options (p.53)), or b y selec ting Specify M achine from the Graphics D ispla y Machine list in the Scheduler tab of F luen t Launcher . Note The SCHEDULER_TIGHT_COUPLING=1 environmen t variable is not supp orted when running on r emot e Linux machines . 43.3. Starting P arallel ANSY S Fluen t on a Windo ws System You c an r un ANSY S Fluen t on a Windo ws system using either the gr aphic al user in terface (for details , see Starting P arallel ANSY S Fluen t Using F luen t Launcher (p.3047 )) or c ommand line options (f or details , see Starting P arallel ANSY S Fluen t on a Windo ws System U sing C ommand Line Options (p.3058 )). Imp ortant See the separ ate installa tion instr uctions f or mor e inf ormation ab out installing par allel ANSY S Fluen t for Windo ws.The star tup instr uctions b elow assume tha t you ha ve pr operly set up the nec essar y sof tware, based on the appr opriate installa tion instr uctions . For additional inf ormation, see the f ollowing sec tion: 43.3.1. Starting P arallel ANSY S Fluen t on a Windo ws System U sing C ommand Line Options 43.3.1. Starting P arallel ANSY S Fluen t on a Windo ws System U sing C ommand Line Options To star t the par allel v ersion of ANSY S Fluen t using c ommand line options , you c an use the f ollowing syntax in a C ommand P rompt windo w: fluent version-t npr ocs[-gpgpu= ngpgpus] [-p interconnec t] [-mpi= mpi_t ype] [-cnf= hosts] Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3058Parallel P rocessingwher e •version must b e replac ed b y the v ersion of ANSY S Fluen t you w ant to run (2d,3d,2ddp , or 3ddp ). •-t npr ocs specifies the numb er of pr ocesses t o use .When the -cnf option is pr esen t, the hosts argumen t is used t o det ermine which machines t o use f or the par allel job . For e xample , if ther e are 8 machines list ed in the hosts file and y ou w ant to run a job with 4 pr ocesses , set npr ocs to 4 (tha t is,-t4 ) and ANSY S Fluen t will use the first 4 machines list ed in the hosts file . Note tha t this do es not apply t o the C omput e Cluster Server (C CS). If the -gpgpu option is used ,npr ocs must b e chosen such tha t the numb er of solv er pr ocesses per machine is equal on all machines . •-p interconnec t (optional) sp ecifies the t ype of in terconnec t.The ethernet interconnec t is used b y default if the option is not e xplicitly sp ecified . See Table 43.2: Supp orted In terconnec ts for the Windo ws Plat- form (p.3060 ),Table 43.3: Available MPI s for Windo ws Platforms (p.3060 ), and Table 43.4: Supp orted MPI s for Windo ws Architectures (P er In terconnec t) (p.3061 ) for mor e inf ormation. •-mpi= mpi_t ype (optional) sp ecifies the MPI implemen tation. If the option is not sp ecified , the default MPI for the giv en in terconnec t (IBM MPI) will b e used (the use of the default MPI is r ecommended). The a vailable MPIs for Windo ws are sho wn in Table 43.3: Available MPI s for Windo ws Platforms (p.3060 ). •-cnf= hosts (optional) sp ecifies the hosts file , which c ontains a list of the machines on which y ou w ant to run the par allel job; if this option is not used , then the session will r un on the lo cal machine . If the hosts file is not lo cated in the f older wher e you ar e typing the star tup c ommand , you must supply the full pa th- name t o the file . You c an use a plain t ext edit or such as N otepad t o cr eate the hosts file .The only r estriction on the filename is tha t ther e should b e no spac es in it. For e xample ,hosts.txt is an acc eptable hosts file name , but my hosts.txt is not. Your hosts file (f or e xample ,hosts.txt ) migh t contain the f ollowing en tries: machine1 machine2 Imp ortant The last en try must b e followed b y a blank line . If a machine in the net work is a multipr ocessor , you c an list it mor e than onc e. For e xample , if ma- chine1 has 2 CPU s, then, to tak e ad vantage of b oth CPU s (and similar ly for multic ore machines), the hosts.txt file should list machine1 twice: machine1 machine1 machine2 By default , Fluen t allo cates ranks t o machines in c ontiguous blo cks, wher e the blo ck siz es ar e as equal as p ossible .You c an c ontrol the p er machine blo ck allo cation siz e using the machine X:Y convention in the hosts sp ecific ation, wher e Y is the pr ocess blo ck c oun t for machine X.The pr ocess assignmen t will c ycle thr ough the machine list un til all pr ocesses ar e allo cated in sp ecified blo cks. A fully r ound-r obin assignmen t of pr ocesses c an b e achie ved b y setting the machine blo ck allo cation sizes to 1 (f or e xample ,machine1:1 ,machine2:1 , and so on). 3059Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Starting P arallel ANSY S Fluen t on a Windo ws System•-gpgpu= ngpgpus specifies the numb er of GPGPU s per machine t o use f or AMG e xecution. Note tha t when this option is used , the numb er of solv er pr ocess p er machine must b e equal on all machines and ngpgpus must b e chosen such tha t the numb er of solv er pr ocesses p er machine is an in teger multiple of ngpgpus. That is, for npr ocs solv er pr ocesses r unning on M machines using ngpgpus GPGPUS p er machine: See Using G ener al Purpose G raphics P rocessing U nits (GPGPU s) With the A lgebr aic M ultigr id (AMG) S olv- er (p.3093 ) for mor e inf ormation ab out using GPGPU acc eleration. For e xample , the full c ommand line t o star t a 3D par allel job on the first 4 machines list ed in a hosts file c alled hosts.txt is as f ollows: fluent 3d -t4 -cnf=hosts.txt As another e xample , the full c ommand line t o star t a 3D symmetr ical multipr ocessing (SMP) par allel job on 4 machines is as f ollows: fluent 3d -t4 In either c ase, the default c ommunic ation libr ary (IBM MPI), and the default in terconnec t (aut oma tically selec ted b y the MPI used , or ethernet ) will b e used sinc e these options ar e not sp ecified . The first time tha t you tr y to run ANSY S Fluen t in par allel, you will b e pr ompt ed f or inf ormation ab out the cur rent Windo ws acc oun t. The supp orted in terconnec ts for dedic ated par allel win64 Windo ws machines , the asso ciated MPI s for them, and the c orresponding syn tax ar e list ed in Table 43.2: Supp orted In terconnec ts for the Windo ws Platform (p.3060 ) - Table 43.4: Supp orted MPI s for Windo ws Architectures (P er In terconnec t) (p.3061 ). Table 43.2: Supp orted In terconnec ts for the Windo ws Platform Interconnec ts Archit ecture Processor Platform ethernet (default),infiniband win64 64-bit Windo ws Table 43.3: Available MPI s for Windo ws Platforms Notes Communic ation Libr ary Syntax (flag) MPI (1), (2), (3) IBM MPI -mpi=ibmmpi ibmmpi (1), (4) Microsof t MPI -mpi=msmpi msmpi (1), (2), (5) Intel MPI -mpi=intel intel (1) U sed with S hared M emor y Machine (SHM) wher e the memor y is shar ed b etween the pr ocessors on a single machine . (2) U sed with D istribut ed M emor y Machine (DMM) wher e each pr ocessor has its o wn memor y asso ciated with it. (3) IBM P latform MPI C ommunit y Edition is installed with F luen t, which is limit ed t o 4096 pr ocesses without an additional lic ense . Refer to IBM P latform MPI with High (>4096) P rocess C oun t for details . (4) U sed with a job scheduler t o run on a Windo ws high p erformanc e computing ser ver (HPC). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3060Parallel P rocessing(5) B y default , the In tel MPI ma y fail when mixing har dware for c omput e no des. As a w orkaround , you can use the f ollowing en vironmen t setting: I_MPI_PLATFORM zero Table 43.4: Supp orted MPI s for Windo ws Archit ectures (P er In terconnec t) Infiniband Ether net Archit ecture msmpi ibmmpi (default),intel ,msmpi win64 43.3.1.1. Star ting P arallel ANSY S Fluent with the M icrosof t Job Scheduler The M icrosof t Job Scheduler allo ws you t o manage multiple jobs and tasks , allo cate machine r esour ces, send tasks t o comput e no des, and monit or jobs , tasks , and c omput e no des. The Windo ws Server op erating sy stems include a c omput e clust er ser ver (C CS) and a high p erformanc e computing ser ver (HPC) tha t combines the M icrosof t MPI t ype (msmpi ) with the M icrosof t Job Scheduler . ANSY S Fluen t provides a means of using the M icrosof t Job Scheduler using the f ollowing flag in the par allel c ommand: -ccp head-no de-name wher e -ccp indic ates the use of the c omput e clust er ser ver pack age, and head-no de-name indic ates the name of the head no de of the machine clust er. For e xample , if y ou w ant to use the M icrosof t Job Scheduler t o run a 3D mo del on 2 no des, the c or- responding c ommand syn tax w ould b e: fluent 3d -t2 -ccp head-no de-name Imp ortant Both the IBM MPI t ype (ibmmpi ) and the In tel MPI (intel ) are not supp orted with the Microsof t Job Scheduler . Note When using M icrosof t Job Scheduler , the b est in terconnec t is aut oma tically selec ted b y MS-MPI. Though the usage descr ibed pr eviously is r ecommended as an initial star ting p oint for running ANSY S Fluen t with the M icrosof t Job Scheduler , ther e ar e fur ther options pr ovided t o meet y our sp ecific needs . ANSY S Fluen t allo ws you t o do an y of the f ollowing with the M icrosof t Job Scheduler : •Request r esour ces fr om the M icrosof t Job Scheduler first , before you launch ANSY S Fluen t. This is done b y first submitting a job tha t will r un un til canceled , as sho wn in the f ollowing e xample: job new/scheduler: head-no de-name/numprocessors:2 /rununtilcanceled:true This e xample r equests a 2-no de r esour ce on a clust er named head-no de-name .You will see tha t a job is cr eated with the job ID job-id : 3061Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Starting P arallel ANSY S Fluen t on a Windo ws Systemjob submit/scheduler: head-no de-name/id: job-id Then check if the r esour ces ha ve been allo cated: job view job-id/scheduler: head-no de-name If the r esour ces ar e ready, you c an star t ANSY S Fluen t using the job ID: fluent 3d -t2 -ccp head-no de-name-jobid= job-id This job will b e reusable un til you decide t o cancel it , at which p oint you must en ter the f ollowing: job cancel job-id/scheduler: head-no de-name •Have ANSY S Fluen t submit a C CS job , but dela y the launching of ANSY S Fluen t un til the ac tual r esour ces are allo cated. This is done b y sp ecifying the job ID as -1, as sho wn in the f ollowing e xample: fluent 3d -t2 -ccp head-no de-name-jobid=-1 If you w ant to stop the job applic ation, click the Canc el butt on. ANSY S Fluen t will pr ompt y ou f or confir mation, and then clean up the p ending job and e xit. •Run y our job using XML t empla te files . This is done b y first cr eating an XML t empla te file , such as sho wn in the f ollowing e xample: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3062Parallel P rocessingwher e fluent-sharename is the name of the shar ed dir ectory pointing t o wher e ANSY S Fluen t is installed (f or e xample ,C:\Program Files\ANSYS Inc\v195\fluent ). Imp ortant Note tha t you must cr eate a jour nal file tha t exits ANSY S Fluen t at the end of the r un, and r efer to it using the -i flag in y our XML t empla te file (bs1.jou in the pr evious example). After y ou ha ve sa ved the file and giv en it a name (f or e xample ,job1.xml ), you c an submit the job as sho wn: job submit /jobfile:job1.xml •Run the job in ba tch mo de without displa ying the ANSY S Fluen t graphic al user in terface. The f ollowing is an e xample of such a ba tch mo de job: job submit /scheduler: head-no de-name /numprocessors:2 /workdir:\\file-server\home\user\ \\head-node\fluent-sharename\ntbin\win64\fluent.exe 3d -t2 -i bs1.jou wher e fluent-sharename is the name of the shar ed dir ectory pointing t o wher e ANSY S Fluen t is installed (f or e xample ,C:\Program Files\ANSYS Inc\v195\fluent ). Imp ortant –Note tha t you must cr eate a jour nal file tha t exits ANSY S Fluen t at the end of the r un, and refer to it using the -i flag in y our ba tch mo de job submission ( bs1.jou in the pr evious example). –You c an star t ANSY S Fluen t jobs fr om an y machine on which is installed either the full C CP or the C CP clien t tools, but not e tha t all the machines must ha ve the same v ersion installed . 43.4. Starting P arallel ANSY S Fluen t on a Linux S ystem You c an r un ANSY S Fluen t on a Linux sy stem using either the gr aphic al user in terface (for details , see Starting P arallel ANSY S Fluen t Using F luen t Launcher (p.3047 )) or c ommand line options (f or details , see Starting P arallel ANSY S Fluen t on a Linux S ystem U sing C ommand Line Options (p.3064 ) and Setting U p Your R emot e Shell and S ecur e Shell C lients (p.3066 )). Imp ortant On some clust ers without acc elerated gr aphics , Fluen t ma y not acc ept k eyboard inputs . If you enc oun ter this b ehavior, set the QT_XKB_CONFIG_ROOT environmen t variable equal to /usr/share/X11/xkb . For additional inf ormation, see the f ollowing sec tions: 3063Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Starting P arallel ANSY S Fluen t on a Linux S ystem43.4.1. Starting P arallel ANSY S Fluen t on a Linux S ystem U sing C ommand Line Options 43.4.2. Setting U p Your R emot e Shell and S ecur e Shell C lients 43.4.1. Starting P arallel ANSY S Fluen t on a Linux S ystem U sing C ommand Line Options To star t the par allel v ersion of ANSY S Fluen t using c ommand line options , you c an use the f ollowing syntax in a c ommand pr ompt windo w: fluent version-t npr ocs[-gpgpu= ngpgpus] [-p interconnec t] [-mpi= mpi_t ype] [-cnf= hosts] wher e •version must b e replac ed b y the v ersion of ANSY S Fluen t you w ant to run (2d,3d,2ddp , or 3ddp ). •-t npr ocs specifies the numb er of pr ocesses t o use .When the -cnf option is pr esen t, the hosts argumen t is used t o det ermine which machines t o use f or the par allel job . For e xample , if ther e are 10 machines list ed in the hosts file and y ou w ant to run a job with 5 pr ocesses , set npr ocs to 5 (tha t is,-t5 ) and ANSY S Fluen t will use the first 5 machines list ed in the hosts file . Note tha t if the -gpgpu option is used ,npr ocs must b e chosen such tha t the numb er of solv er pr ocesses p er machine is equal on all machines . •-p interconnec t (optional) sp ecifies the t ype of in terconnec t.The auto-select interconnec t is used b y default so tha t the b est a vailable in terconnec t is used if the option is not e xplicitly sp ecified . See Table 43.5: Supp orted In terconnec ts for Linux P latforms (P er P latform) (p.3065 ),Table 43.6: Available MPI s for Linux P latforms (p.3066 ), and Table 43.7: Supp orted MPI s for Linux A rchitectures (P er In terconnec t) (p.3066 ) for mor e inf ormation. •-mpi= mpi_t ype (optional) sp ecifies the t ype of MPI. If the option is not sp ecified , the default MPI f or the given in terconnec t will b e used (the use of the default MPI is r ecommended). The a vailable MPI s for Linux are sho wn in Table 43.6: Available MPI s for Linux P latforms (p.3066 ). •-cnf= hosts (optional) sp ecifies the hosts file , which c ontains a list of the machines on which y ou w ant to run the par allel job; if this option is not used , then the session will r un on the lo cal machine . If the hosts file is not lo cated in the dir ectory wher e you ar e typing the star tup c ommand , you must supply the full pathname t o the file . You c an use a plain t ext edit or to cr eate the hosts file .The only r estriction on the filename is tha t ther e should b e no spac es in it. For e xample ,hosts.txt is an acc eptable hosts file name , but my hosts.txt is not. Your hosts file (f or e xample ,hosts.txt ) migh t contain the f ollowing en tries: machine1 machine2 If a machine in the net work is a multipr ocessor , you c an list it mor e than onc e. For e xample , if ma- chine1 has 2 CPU s, then, to tak e ad vantage of b oth CPU s, the hosts.txt file should list machine1 twice: machine1 machine1 machine2 Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3064Parallel P rocessingAs an alt ernative to a hosts file , you c an simply t ype the names of the machines in a list separ ated by commas , as sho wn in the f ollowing e xample:-cnf=machine1,machine1,machine2 . By default , Fluen t allo cates ranks t o machines in c ontiguous blo cks, wher e the blo ck siz es ar e as equal as p ossible .You c an c ontrol the p er machine blo ck allo cation siz e using the machine X:Y convention in the hosts sp ecific ation, wher e Y is the pr ocess blo ck c oun t for machine X.The pr ocess assignmen t will c ycle thr ough the machine list un til all pr ocesses ar e allo cated in sp ecified blo cks. A fully r ound-r obin assignmen t of pr ocesses c an b e achie ved b y setting the machine blo ck allo cation sizes to 1 (f or e xample ,machine1:1 ,machine2:1 , and so on). •-gpgpu= ngpgpus specifies the numb er of GPGPU s per machine t o use f or AMG e xecution. Note tha t when this option is used , the numb er of solv er pr ocess p er machine must b e equal on all machines and ngpgpus must b e chosen such tha t the numb er of solv er pr ocesses p er machine is an in teger multiple of ngpgpus. That is, for npr ocs solv er pr ocesses r unning on M machines using ngpgpus GPGPUS p er machine: See Using G ener al Purpose G raphics P rocessing U nits (GPGPU s) With the A lgebr aic M ultigr id (AMG) S olv- er (p.3093 ) for mor e inf ormation ab out using GPGPU acc eleration. For e xample , to use the Infiniband in terconnec t, and t o star t the 3D solv er with 4 c omput e no des on the machines defined in the t ext file c alled fluent.hosts , you c an en ter the f ollowing in the c om- mand pr ompt: fluent 3d -t4 -pinfiniband -cnf=fluent.hosts Note tha t if the optional -cnf= hosts is sp ecified , a comput e no de will b e spa wned on each machine listed in the file hosts . Also, ANSY S Fluen t provides a fault-t oler ance feature on Infiniband Linux clust ers r unning OFED .To invoke this f eature, use the c ommand line flag -pinfiniband.ofedft (or -pib.ofedft ), which enables tr anspar ent port fail-o ver and high-a vailabilit y features using the IBM MPI. Note tha t while the simula tions pr oceed mor e robustly with this option, ther e ma y be some degr adation in p erformanc e. During star tup, ANSY S Fluen t will cr eate very small t ext files in the /tmp area. If you w ould lik e to specify a diff erent location f or these files , set the f ollowing en vironmen t variable:export FL_TMPDIR= directory. The supp orted in terconnec ts for par allel Linux machines ar e list ed b elow (Table 43.5: Supp orted In ter- connec ts for Linux P latforms (P er P latform) (p.3065 ),Table 43.6: Available MPI s for Linux P latforms (p.3066 ), and Table 43.7: Supp orted MPI s for Linux A rchitectures (P er In terconnec t) (p.3066 )), along with their as- sociated c ommunic ation libr aries, the c orresponding syn tax, Table 43.5: Supp orted In terconnec ts for Linux P latforms (P er P latform) Interconnec ts/S ystems* Archit ecture Processor Platform ethernet ,infiniband ,crayx lnamd64 64-bit Linux 3065Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Starting P arallel ANSY S Fluen t on a Linux S ystem(*) N ode pr ocesses on the same machine c ommunic ate by shar ed memor y. ANSY S Fluen t lets the MPI autoselec t the b est in terconnec t available on the sy stem. Users c an sp ecify an in terconnec t to override that selec tion. Ether net is the fallback choic e. Table 43.6: Available MPI s for Linux P latforms Notes Communic ation Libr ary Syntax (flag) MPI Gener al pur pose f or SMP s and clust ers (1)IBM MPI -mpi=ibmmpi ibmmpi Gener al pur pose f or SMP s and clust ersIntel MPI -mpi=intel intel Open sour ce MPI-2 implemen tation. For b oth SMP s and clust ers.Open MPI -mpi=openmpi openmpi Only a vailable on C ray systems .Cray MPI (MPT ) -mpi=cray cray (1) IBM P latform MPI C ommunit y Edition is installed with F luen t, which is limit ed t o 4096 pr ocesses without an additional lic ense . Refer to IBM P latform MPI with High (>4096) P rocess C oun t for details . Table 43.7: Supp orted MPI s for Linux A rchit ectures (P er In terconnec t) Omni-P ath** Propr ietar y SystemsInfiniband Ether net Archit ecture ibmmpi (default) and intelcray * ibmmpi (default), intel , and openmpiibmmpi (default), intel , and openmpilnamd64 (*) U sing the C ray pla tform, the Ex treme Sc alabilit y Mode (ESM) option is used b y default , emplo ying the na tive Cray MPI (MPT ) libr ary for par allel c ommunic ation. Optionally , you c an use the C luster Compa tibilit y Mode (C CM) mo de, in which the standar d IBM MPI libr ary is used f or par allel c ommunic- ation. For simula tions with high c ore coun ts (f or e xample , above 1000 c ores), the ESM mo de is r ecom- mended f or b etter p erformanc e. Note tha t when using MPT v ersion 5.0 and higher (up t o, but not in- cluding 7.0), you must set the f ollowing en vironmen t variable:export FLUENT_USE_CRAY_MPT5=1 . (**) F or In tel Omni-P ath ar chitecture, Omni-P ath sof tware 10.2 or higher is r ecommended , and In tel MPI is pr eferred. (Linux Only) To enable a job-scheduler-supp orted na tive remot e no de acc ess mechanism, you c an use the -scheduler_tight_coupling command line option. For details ab out the MPI / job scheduler combina tions tha t are supp orted f or this tigh t coupling , see Running F luen t Using a L oad M anager . 43.4.2. Setting U p Your Remot e Shell and S ecur e Shell C lien ts For clust er computing on Linux sy stems , most par allel v ersions of ANSY S Fluen t will r equir e the user accoun t set up such tha t you c an c onnec t to all no des on the clust er (using either the r emot e shell (rsh ) clien t or the secur e shell (ssh ) clien t) without ha ving t o en ter a passw ord each time f or each machine . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3066Parallel P rocessingProvided tha t the appr opriate ser ver daemons (either rshd or sshd ) are running , this sec tion br iefly descr ibes ho w you c an c onfigur e your sy stem in or der t o use ANSY S Fluen t for par allel c omputing . 43.4.2.1. Configuring the rsh Client The r emot e shell clien t (rsh ), is widely deplo yed and used . It is gener ally easy t o configur e, and in- volves adding all the machine names , each on a single line , to the .rhosts file in y our home dir ectory. If you r efer to the machine y ou ar e cur rently lo gged on as the ‘clien t’, and if y ou r efer to the r emot e machine t o which y ou seek passw ord-less lo gin as the ‘server’, then on the ser ver, you c an add the name of y our clien t machine t o the .rhosts file.The name c ould b e a lo cal name or a fully qualified name with the domain suffix. Similar ly, you c an add other clien ts fr om which y ou r equir e similar acc ess to this ser ver.These machines ar e then “trusted” and r emot e acc ess is allo wed without the fur ther need f or a passw ord.This setup assumes y ou ha ve the same user ID on all the machines . Other wise , each line in the .rhosts file must c ontain the machine name as w ell as the user ID f or the clien t that you w ant acc ess t o. Refer to your sy stem do cumen tation f or fur ther usage options . Note tha t for secur ity pur poses , the .rhosts file must b e readable only b y the user . 43.4.2.2. Configuring the ssh Client The secur e shell clien t (ssh ), is a mor e secur e alt ernative than rsh and is also used widely . Depending on the sp ecific pr otocol and the v ersion deplo yed, configur ation in volves a f ew st eps.SSH1 and SSH2 are two cur rent protocols.OpenSSH is an op en implemen tation of the SSH2 protocol and is back wards c ompa tible with the SSH1 protocol.To add a clien t machine , with r espect to user c onfig- uration, the f ollowing st eps ar e involved: 1.Gener ate a public-pr ivate key pair using ssh-keygen (or using a gr aphic al user in terface clien t). For example: % ssh-keygen -t dsa wher e it cr eates a D igital S igna ture Author ity (DSA) t ype key pair . 2.Place your public k ey on the r emot e host. •For SSH1 , inser t the c ontents of the clien t (~/.ssh/identity.pub ) into the ser ver (~/.ssh/authorized_keys ). •For SSH2 , inser t the c ontents of the clien t (~/.ssh/id_dsa.pub ) into the ser ver (~/.ssh/au- thorized_keys2 ). The clien t machine is no w added t o the acc ess list and y ou ar e no longer r equir ed t o type in a passw ord each time . For additional inf ormation, consult y our sy stem administr ator or r efer to your sy stem documen tation. 43.5. Mesh P artitioning and L oad B alancing Information ab out mesh par titioning and load balancing is pr ovided in the f ollowing sec tions: 43.5.1. Overview of M esh P artitioning 43.5.2. Partitioning the M esh A utoma tically 43.5.3. Partitioning the M esh M anually and B alancing the L oad 3067Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Mesh P artitioning and L oad B alancing43.5.4. Using the P artitioning and L oad B alancing D ialog Box 43.5.5. Mesh P artitioning M etho ds 43.5.6. Check ing the P artitions 43.5.7. Load D istribution 43.5.8. Troublesho oting 43.5.1. Overview of M esh P artitioning When y ou use the par allel solv er in ANSY S Fluen t, you must par tition or sub divide the mesh in to groups of c ells tha t can b e solv ed on separ ate pr ocessors (see Figur e 43.5: Partitioning the M esh (p.3069 )). You c an either use the aut oma tic par titioning algor ithms when r eading an unpar titioned mesh in to the par allel solv er (r ecommended appr oach, descr ibed in Partitioning the M esh A utoma tically (p.3069 )), or p erform the par titioning y ourself in the ser ial solv er or af ter reading a mesh in to the par allel solv er (as descr ibed in Partitioning the M esh M anually and B alancing the L oad (p.3071 )). In either c ase, the available par titioning metho ds ar e those descr ibed in Mesh P artitioning M etho ds (p.3083 ).You c an partition the mesh b efore or af ter y ou set up the pr oblem (b y defining mo dels , boundar y conditions , and so on). Note tha t the r elative distr ibution of c ells among c omput e no des will b e main tained dur ing mesh ad- aption, so manual r epar titioning af ter adaption is not r equir ed. For details , see Load D istribution (p.3092 ). If you use the ser ial solv er to set up the pr oblem b efore par titioning , the machine on which y ou p erform this task must ha ve enough memor y to read in the mesh. If your mesh is t oo lar ge t o be read in to the serial solv er, you c an r ead the unpar titioned mesh dir ectly in to the par allel solv er (using the memor y available in all the defined hosts) and ha ve it aut oma tically par titioned . In this c ase y ou will set up the problem af ter an initial par tition has b een made .You will then b e able t o manually r epar tition the case if nec essar y. See Partitioning the M esh A utoma tically (p.3069 ) and Partitioning the M esh M anually and B alancing the L oad (p.3071 ) for additional details and limita tions , and Check ing the P artitions (p.3089 ) for details ab out check ing the par titions . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3068Parallel P rocessingFigur e 43.5: Partitioning the M esh 43.5.2. Partitioning the M esh A utoma tically For aut oma tic mesh par titioning , you c an selec t the par tition metho d and other options f or cr eating the mesh par titions b efore reading a c ase file in to the par allel v ersion of the solv er. For some of the metho ds, you c an p erform pr etesting t o ensur e tha t the b est p ossible par tition is p erformed . See Mesh Partitioning M etho ds (p.3083 ) for inf ormation ab out the par titioning metho ds a vailable in ANSY S Fluen t. Note Architecturally a ware par titioning (see Partitioning (p.3071 )) is p erformed aut oma tically when the c ase file is r ead. If the maximum in ter-machine c ommunic ation is r educ ed b y mor e than 5%, the new par tition mapping will b e applied , and a message is displa yed in the c onsole , for e xample: inter-node communication reduction by architecture-aware remap- ping: 47% 3069Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Mesh P artitioning and L oad B alancingWhile the message indic ates ac tual p oint-to-point net work traffic r educ tion, solv er compu- tational p erformanc e impr ovemen t ma y be somewha t less , and dep ends on the c ase and the sy stem net work configur ation. The pr ocedur e for par titioning aut oma tically in the par allel solv er is as f ollows: 1.(optional) S et the par titioning par amet ers in the Auto Partition M esh dialo g box (Figur e 43.6: The A uto Partition M esh D ialog Box (p.3070 )). Parallel → Gener al → Auto Partition... Figur e 43.6: The A uto Partition M esh D ialo g Box If you ar e reading in a mesh file or a c ase file f or which no par tition inf ormation is a vailable , and you k eep the Case F ile option tur ned on, ANSY S Fluen t will par tition the mesh using the metho d displa yed in the Metho d drop-do wn list. If you w ant to sp ecify the par titioning metho d and asso ciated options y ourself , the pr ocedur e is as follows: a.Turn off the Case F ile option. The other options in the dialo g box will b ecome a vailable . b.Selec t the par tition metho d in the Metho d drop-do wn list. The choic es ar e the t echniques descr ibed in Partition M etho ds (p.3083 ). c.You c an cho ose t o indep enden tly apply par titioning t o each c ell z one , or y ou c an allo w par titions to cr oss z one b oundar ies using the Across Z ones check butt on (which is enabled b y default). It is r ecommended tha t you lea ve this option enabled , as other wise the r esulting par titions ma y be too gr anular ized, which c an c ompr omise p erformanc e. Note tha t disabling this option has no eff ect when y ou ha ve selec ted Metis for the Metho d. d.If you ha ve chosen the Principal A xes or Cartesian A xes metho d, you c an impr ove the par titioning by enabling the aut oma tic t esting of the diff erent bisec tion dir ections b efore the ac tual par titioning occurs .To use pr etesting , turn on the Pre-Test option. Pretesting is descr ibed in Pretesting (p.3088 ). e.Click OK. If you ha ve a c ase file wher e you ha ve alr eady par titioned the mesh, and the numb er of par titions divides e venly in to the numb er of c omput e no des, you c an k eep the default selec tion of Case F ile in the Auto Partition M esh dialo g box.This instr ucts ANSY S Fluen t to use the par titions in the case file . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3070Parallel P rocessing2.Read the c ase file . File → Read → Case... 43.5.2.1. Reporting D uring A uto Partitioning As the mesh is aut oma tically par titioned , some inf ormation ab out the par titioning pr ocess will b e displa yed in the c onsole . If you w ant additional inf ormation, you c an displa y a r eport from the Parti- tioning and L oad B alancing dialo g box after the par titioning is c omplet ed. Parallel → Gener al → Partition/L oad B alanc e... When y ou click the Print Active Partitions or Print Stored P artitions butt on in the Partitioning and L oad B alancing dialo g box, ANSY S Fluen t will displa y the par tition ID , numb er of c ells, faces, and in terfaces, and the r atio of in terfaces to fac es for each ac tive or st ored par tition in the c onsole . In addition, it will displa y the minimum and maximum c ell, face, interface, and fac e-ratio v ariations . For details , see Interpreting P artition S tatistics (p.3089 ).You c an e xamine the par titions gr aphic ally b y following the dir ections in Check ing the P artitions (p.3089 ). 43.5.3. Partitioning the M esh M anually and B alancing the L oad Automa tic par titioning in the par allel solv er (descr ibed in Partitioning the M esh A utoma tically (p.3069 )) is the r ecommended appr oach t o mesh par titioning , but it is also p ossible t o par tition the mesh manually in either the ser ial solv er or the par allel solv er. After aut oma tic or manual par titioning , you will b e able t o insp ect the par titions cr eated (f or details , see Check ing the P artitions (p.3089 )) and op- tionally r epar tition the mesh, if nec essar y. Again, you c an do so within the ser ial or the par allel solv er, using the Partitioning and L oad B alancing dialo g box. A par titioned mesh ma y also b e used in the serial solv er without an y loss in p erformanc e. 43.5.3.1. Guidelines for P artitioning the Mesh The f ollowing st eps ar e recommended f or par titioning a mesh manually : 1.Partition the mesh using the default metho d (Metis ).Metis will gener ally pr oduce the b est qualit y partitions f or most pr oblems and no fur ther user in tervention should b e nec essar y. Note tha t the Cartesian A xes metho d can b e a r easonable alt ernative with less memor y overhead . 2.Examine the par tition sta tistics , which ar e descr ibed in Interpreting P artition S tatistics (p.3089 ).Your aim is t o minimiz e the Maximum value of the Partition boundary face count ratio , while main taining a balanc ed load . For a giv en mesh, the Mean cell count deviation is a measur e of the maximum load imbalanc e for a metho d. If the sta tistics ar e not sa tisfac tory for a pr oblem, you c an tr y one of the other par titioning metho ds. Instr uctions f or manual par titioning ar e pr ovided b elow. 43.5.4. Using the P artitioning and L oad B alancing D ialo g Box 43.5.4.1. Partitioning In or der t o par tition the mesh, you must selec t the par tition metho d for cr eating the mesh par titions , set the numb er of par titions , selec t the z ones and/or r egist ers, and cho ose the optimiza tions t o be 3071Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Mesh P artitioning and L oad B alancingused . For some metho ds, you c an also p erform pr etesting t o ensur e tha t the b est p ossible par tition is performed . Onc e you ha ve set all the par amet ers in the Partitioning and L oad B alancing dialo g box to your sa tisfac tion, click the Partition butt on t o sub divide the mesh in to the selec ted numb er of par titions using the pr escr ibed metho d and optimiza tion(s). For recommended par titioning str ategies see Guidelines f or P artitioning the M esh (p.3071 ). You c an set the r elevant inputs in the Partitioning and L oad B alancing dialo g box (Figur e 43.7: The Partitioning and L oad B alancing D ialog Box (p.3072 )) in the f ollowing manner : Parallel → Gener al → Partition/L oad B alanc e... Figur e 43.7: The P artitioning and L oad B alancing D ialo g Box 1.Selec t the Metho d from the dr op-do wn list. The choic es ar e descr ibed in Partition M etho ds (p.3083 ). 2.In the Options tab a.Set the desir ed numb er of mesh par titions in the Numb er of P artitions field .You c an use the c oun ter arrows to incr ease or decr ease the v alue , inst ead of t yping in the b ox.The numb er of mesh par titions must b e an in teger numb er tha t is divisible b y the numb er of pr ocessors a vailable f or par allel c om- puting . b.Set the Rep orting Verb osit y.This allo ws you t o control wha t is displa yed in the c onsole . For details , see Reporting D uring P artitioning (p.3080 ). c.You c an cho ose t o indep enden tly apply par titioning t o each c ell z one , or y ou c an allo w par ti- tions t o cr oss z one b oundar ies using the Across Z ones check butt on (which is enabled b y default). It is r ecommended tha t you lea ve this option enabled , as other wise the r esulting partitions ma y be too gr anular ized, which c an c ompr omise p erformanc e. Note tha t disabling this option has no eff ect when y ou ha ve selec ted Metis for the Metho d. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3072Parallel P rocessingd.If you ar e using the Metis metho d, you ha ve the option of enabling Laplac e Smoothing .This option can b e used t o pr event par tition b oundar ies fr om passing thr ough ar eas of high asp ect ratio c ells. This c an impr ove convergenc e in d ynamic mesh c ases and other c ases with r egions of highly str etched cells. After enabling Laplac e Smoothing , you c an sp ecify the Cutoff A spect Ratio.The C utoff A spect Ratio c orresponds r oughly t o the maximum asp ect ratio allo wable along a par tition b oundar y. e.Selec t the Reor der ing M etho d for par titions t o optimiz e par allel p erformanc e: •Archit ecture Aware:This is the default option and it acc oun ts for the sy stem ar chitecture and network topology in r emapping the par titions t o the pr ocessors . •Reverse C uthill-M cKee:This option minimiz es the band width of the c omput e-no de c onnec tivit y matrix (the maximum distanc e between t wo connec ted pr ocesses) without inc orporating the system ar chitecture. The r eordering metho ds ar e par allel p erformanc e tuning options . After the c ase is initially partitioned f or par allel pr ocessing , the par tition r eordering st ep will r emap the par titions in a mor e optimal w ay to impr ove par allel p erformanc e. Imp ortant The A rchitecture-aware reordering metho d is not applic able when only a single machine is used f or the simula tion. After initially loading the c ase in to a par allel session, you c an click the Reor der butt on t o reorder the par titions .The nec essar y algor ithms ar e execut ed and ANSY S Fluen t will r eport if it c an find a mor e optimal mapping f or the par titions , as w ell as the p otential impr ovemen t in in ter- machine c ommunic ations . If the r eported impr ovemen t is signific ant (sa y, mor e than 5%), then you c an click the Use S tored P artitions butt on t o use the new par tition mapping .This will gener ally en tail lar ge da ta tr ansf ers amongst all the pr ocesses , and another r eliable metho d to use the new par titions w ould b e to wr ite out a c ase file and load it back in t o a new par allel session. The pr ocess is similar t o re-par titioning with a new par titioning metho d, for e xample . Note tha t sometimes , dep ending on the clust er configur ation and initial c ase par titioning , and 3073Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Mesh P artitioning and L oad B alancingif the par titions ha ve alr eady been r eordered, no impr ovemen t is p ossible , and this will b e re- ported in the c onsole af ter click ing the Reor der butt on.You c an simply c ontinue in this c ase, and ther e will b e no eff ect on the simula tion. Also, not e tha t par tition r eordering is sp ecific to the cur rent par allel c onfigur ation and should b e repeated if the numb er of machines used changes dur ing subsequen t computa tions . 3.In the Optimiza tion tab a.You c an enable and c ontrol the desir ed optimiza tion metho ds (descr ibed in Optimiza tions (p.3087 )). You c an enable the Merge and Smooth schemes b y enabling the check butt on ne xt to each one . For each scheme , you c an also set the numb er of Iterations . Each optimiza tion scheme will b e applied until appr opriate criteria ar e met , or the maximum numb er of it erations has b een e xecut ed. If the Iterations coun ter is set t o 0, the optimiza tion scheme will b e applied un til completion, with no limit on maximum numb er of it erations . b.Choosing the Principal A xes or Cartesian A xes metho d, you c an impr ove the par titioning b y enabling the aut oma tic t esting of the diff erent bisec tion dir ections b efore the ac tual par titioning o ccurs .To use pr etesting , enable the Pre-Test option. Pretesting is descr ibed in Pretesting (p.3088 ). 4.In the Zones and/or Regist ers lists , selec t the z one(s) and/or r egist er(s) f or which y ou w ant to par tition. For most c ases , you will selec t all Zones (the default) t o par tition the en tire domain. See b elow for details . 5.You c an assign selec ted Zones and/or Regist ers to a sp ecific par tition ID b y en tering a v alue f or the Set Selec ted Z ones and Regist ers t o Partition ID . For e xample , if the Numb er of par titions f or y our mesh is 2, then y ou c an only use IDs of 0 or 1. If you ha ve thr ee par titions , then y ou c an en ter IDs of 0,1, or 2.This c an b e useful in situa tions wher e the gr adien t at a r egion is k nown t o be high. In such c ases , you can mar k the r egion or z one and set the mar ked c ells t o one of the par tition IDs , ther eby pr eventing the partition fr om going thr ough tha t region. This in tur n will facilita te convergenc e.This is also useful in cases wher e mesh manipula tion t ools ar e not a vailable in par allel. In this c ase, you c an assign the r elated cells t o a par ticular ID so tha t the mesh manipula tion t ools ar e no w func tional. If you ar e running the par allel solv er, and y ou ha ve mar ked y our r egion and assigned an ID t o the selec ted Zones and/or Regist ers, click the Use S tored P artitions butt on t o mak e the new partitions v alid. Refer to the e xample descr ibed la ter in this sec tion f or a demonstr ation of ho w selec ted r egist ers are assigned t o a par tition ( Example of S etting S elec ted C ell R egist ers t o Specified P artition IDs (p.3077 )). 6.In the Weigh ting tab ( Figur e 43.8: The Weigh ting Tab in the P artitioning and L oad B alancing Dialog Box (p.3075 )), you c an set the appr opriate weigh ts pr ior t o par titioning the mesh, to impr ove load balancing and o verall p erformanc e.You c an c ontrol w eigh ts for c ells, solid c ell z ones ,VOF, DPM, and ISA T table lo okup.You c an r ely on ANSY S Fluen t timers t o set the w eigh t scaling and optionally mo dify it (b y enabling the User S pecified option); alternatively, you c an use mo del- weigh ted par titioning , so tha t Fluen t aut oma tically c alcula tes the w eigh ting based on the c ell coun t and the mo dels and a ttribut es used as w eigh ts. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3074Parallel P rocessingFigur e 43.8: The Weigh ting Tab in the P artitioning and L oad B alancing D ialo g Box a.Enable Faces p er C ell so tha t the par titioning assigns a w eigh t to each c ell based on its numb er of faces.This t ype of w eigh ting is ad vantageous when the c ase has mix ed or p olyhedr al cell z ones . If you enable the User S pecified check b ox, the w eigh t assigned t o each c ell will b e the numb er of faces plus the Additional C ell Weigh t you en ter in the numb er-en try box under Value . By default the Faces p er C ell weigh ting is enabled with the Additional C ell Weigh t set t o 2. b.Enable Solid Z ones weigh ting so tha t the par titioning tak es solid c ells in to consider ation. If you enable the User S pecified check b ox, you c an sp ecify a Value for the Solid C ell Weigh t Ratio.This v alue is r elative to the fluid c ell w eigh ting; typic ally, it should b e less than 1, sinc e the c alcula tion is usually quick er and less c omputa tionally e xpensiv e for the solid z one c ompar ed to the fluid z one .When using mo del-w eigh ted par titioning , the default v alue of 0.1 is appr o- priate, other wise a lar ger v alue ma y be mor e suitable . For c ases tha t ha ve solid z ones , the Solid Z ones weigh ting is enabled b y default. c.Enable VOF weigh ting t o allo w the par titioning t o consider the imbalanc e caused b y the fr ee sur face reconstr uction with the geo-r econstr uct scheme .Therefore, it is only a vailable when using the VOF model with geometr ic reconstr uction. You ma y use the user-sp ecified v alue b efore timers ar e collec ted, or if y ou w ant to sp ecify a v alue other than timing sta tistics .The sp ecified v alue is the VOF pr oportion of the t otal c omputa tional eff ort. d.Enable DPM weigh ting t o set the w eigh t of DPM par ticles r elative to the c ontinuous phase . DPM weigh ts ar e valid when y ou ha ve par ticle tr acking in y our simula tion, wher e the user-sp ecified v alue is the DPM pr oportion of the t otal c omputa tional eff ort relative to the c ontinuous phase . Note tha t this is a vailable only when y ou ha ve injec tions defined . For details , see Modeling D iscrete Phase (p.1911 ). The DPM w eigh t tak es in to acc oun t the distr ibution of the tr acking eff ort over the par titions and it is a vailable af ter a t least one c alcula tion st ep with par ticle tr acking. Displa ying P article Tracks do es not change the w eigh ts.The c omputa tional eff ort is det ermined b y the numb er of DPM st eps p erformed in each c ell.This w eigh t becomes mor e imp ortant when the time f or the par ticle tr acking of par ticles e xceeds the time f or solving the flo w. Enabling this option in the Weigh ting tab enables the c oun ting of the par ticle st eps in the c ells.These v alues ar e 3075Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Mesh P artitioning and L oad B alancingavailable f or c ontour and v ector plots when using the Discr ete Phase M odel and DPM S teps per C ell variable . After repar titioning , the DPM w eigh ts ar e reset b efore the ne xt par ticle tracking. It is gener ally pr eferable t o par tition along the dominan t pa th of the par ticles in or der to minimiz e par ticles cr ossing par tition b oundar ies and ther eby reducing asso ciated c ommu- nication c osts . However, par titioning should also c onsider load balanc e for the other mo dels , especially the c ontinuous phase , and mo del w eigh ting pr ovides a means t o eff ectively load balanc e the o verall simula tion. Selec t the Hybr id Optimiza tion option t o enable the h ybrid optimiza tion par tition w eigh ting metho d for DPM. This metho d balanc es the load acr oss machines , and , within each machine , the h ybrid par allel DPM metho d is used t o mak e sur e the load is balanc ed b y multi-thr eading . First, the domain is split based on the mo del w eigh ts of each c ell and then par titioned acr oss a numb er of machines . Finally , each machine is par titioned acc ording t o the numb er of c ores. This allo ws you t o ha ve a balanc ed numb er of c ells in each par tition, at the same time ha ving a balanc ed numb er of par ticles on each machine , which will b e fur ther balanc ed b y the h ybrid DPM metho d.This optimiza tion option is also applic able t o the discr ete elemen t metho d (DEM) collision mo del. e.Enable ISAT weigh ting t o balanc e the load dur ing the ISA T table lo okup f or the stiff-chemistr y Lam- inar, EDC or PDF Transp ort mo dels .The ISA T algor ithm builds an unstr uctured table in species di- mensions f or st orage and r etrieval of the chemistr y mappings . Since chemistr y is usually c omputa- tionally e xpensiv e, this st orage/r etrieval can b e very time-c onsuming (f or inf ormation ab out ISA T, refer to In-S itu A daptiv e Tabula tion (ISA T) in the Theor y Guide ). Each par allel no de builds its o wn table , and ther e is no message passing t o tables on other no des. As some no des ma y ha ve mor e chemic al reactions than others (f or e xample one par allel no de ma y contain just air a t a c onstan t temp erature, in which c ase the ISA T table will c ontain only one en try and c alcula tion will b e rapid), ther e ma y be a load imbalanc e.The d ynamic load balancing algor ithm will migr ate cells fr om high computa tional load no des t o low computa tional load no des. If you decide t o sp ecify a v alue , this user-sp ecified v alue is the ISA T pr oportion of the t otal computa tional eff ort. f.For the Metis par tition metho d, you ha ve the option of using mo del-w eigh ted par titioning . The objec tive of mo del-w eigh ted par titioning is t o balanc e the o verall numb er of c ells, as w ell as the time needed f or the selec ted mo dels (tha t is, the enabled Weigh t Types, descr ibed previously). This is sp ecific ally useful f or c ases tha t could p otentially lead t o a load imbal- ance—f or e xample: when using the discr ete phase mo del, as the distr ibution of par ticles c ould be diff erent acr oss par titions and thus c ause an imbalanc e; or f or c ases with a lar ge pr oportion of solid z ones , as solid z ones r equir e less pr ocessing time / e xpense than fluid z ones . Each mo del is c onsider ed as a c onstr aint, and a base c onstr aint is aut oma tically in troduced for the o verall numb er of c ells.When par titioning , ANSY S Fluen t will aut oma tically c alcula te the w eigh ts for these c onstr aints, and balanc e each of them. To use mo del-w eigh ted par titioning , ensur e tha t the Metis par tition metho d is selec ted, and enable the appr opriate mo dels under Weigh t Types in the Weigh ting tab; not e tha t for VOF, DPM , and ISAT, the asso ciated User S pecified and Value settings ar e not r elevant).Then mak e sur e tha t the f ollowing t ext command is enabled (which it is b y default) pr ior t o par ti- tioning: parallel → partition → set → model-weighted-partition Note tha t you c an get additional inf ormation sp ecific t o the c onstr aints b y setting the Rep orting Verb osit y to 2 in the Options tab . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3076Parallel P rocessing7.When using the d ynamic mesh mo del in y our par allel simula tions , the Partition dialo g box includes an Auto Repar tition option and a Repar tition In terval setting .These par allel par titioning options are pr ovided b ecause ANSY S Fluen t migr ates c ells when lo cal remeshing and smo othing ar e per- formed .Therefore, the par tition in terface becomes v ery wr inkled and the load balanc e ma y det eri- orate. By default , the Auto Repar tition option is selec ted, wher e a p ercentage of in terface fac es and loads ar e aut oma tically tr aced.When this option is selec ted, ANSY S Fluen t aut oma tically de- termines the most appr opriate repar tition in terval based on v arious simula tion par amet ers. Sometimes , using the Auto Repar tition option pr ovides insufficien t results , ther efore, the Repar- tition In terval setting c an b e used .The Repar tition In terval setting lets y ou t o sp ecify the in terval (in time st eps or it erations r espectively) when a r epar tition is enf orced.When r epar titioning is not desir ed, you c an set the Repar tition In terval to zero. Imp ortant Note tha t when d ynamic meshes and lo cal remeshing is utiliz ed, updated meshes ma y be sligh tly diff erent in par allel ANSY S Fluen t (when c ompar ed t o ser ial ANSY S Fluen t or when c ompar ed t o a par allel solution cr eated with a diff erent numb er of c omput e nodes), resulting in v ery small diff erences in the solutions . 8.Click the Partition butt on t o par tition the mesh. 9.Click the Use S tored P artitions butt on if y ou decide tha t the new par titions ar e better than the previous ones (if the mesh w as alr eady par titioned). This mak es the newly st ored c ell par titions the ac tive cell par titions .The ac tive cell par tition is used f or the cur rent calcula tion, while the stored c ell par tition (the last par tition p erformed) is used when y ou sa ve a c ase file . 43.5.4.1.1. Example of S etting S elec ted C ell R egist ers t o Sp ecified P artition IDs 1.Start ANSY S Fluen t in par allel. The c ase in this e xample w as par titioned acr oss t wo no des. 2.Read in y our c ase. 3.Displa y the mesh with the Partitions option enabled in the Mesh D ispla y dialo g box (Figur e 43.9: The Partitioned M esh (p.3077 )). Figur e 43.9: The P artitioned M esh 4.Mark your c ells using a r egion c ell regist er (f or details , see Region (p.2759 )).This cr eates a c ell regist er. 3077Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Mesh P artitioning and L oad B alancing5.Open the Partitioning and L oad B alancing dialo g box. 6.Set the Set S elec ted Z ones and Regist ers t o Partition ID to 0 and click the c orresponding butt on. This displa ys the f ollowing output in the ANSY S Fluen t console: >> 2 Active Partitions: ---------------------------------------------------------------------- Collective Partition Statistics: Minimum Maximum Total ---------------------------------------------------------------------- Cell count 459 459 918 Mean cell count deviation 0.0% 0.0% Partition boundary cell count 11 11 22 Partition boundary cell count ratio 2.4% 2.4% 2.4% Face count 764 1714 2461 Mean face count deviation -38.3% 38.3% Partition boundary face count 13 13 17 Partition boundary face count ratio 0.8% 1.7% 0.7% Partition neighbor count 1 1 ---------------------------------------------------------------------- Partition Method Metis Stored Partition Count 2 Done. 7.Click the Use S tored P artitions butt on t o mak e the new par titions v alid.This migr ates the par titions to the c omput e-no des.The following output is then displa yed in the ANSY S Fluen t console: Migrating partitions to compute-nodes. >> 2 Active Partitions: P Cells I-Cells Cell Ratio Faces I-Faces Face Ratio Neighbors 0 672 24 0.036 2085 29 0.014 1 1 246 24 0.098 425 29 0.068 1 ---------------------------------------------------------------------- Collective Partition Statistics: Minimum Maximum Total ---------------------------------------------------------------------- Cell count 246 672 918 Mean cell count deviation -46.4% 46.4% Partition boundary cell count 24 24 48 Partition boundary cell count ratio 3.6% 9.8% 5.2% Face count 425 2085 2461 Mean face count deviation -66.1% 66.1% Partition boundary face count 29 29 49 Partition boundary face count ratio 1.4% 6.8% 2.0% Partition neighbor count 1 1 ---------------------------------------------------------------------- Partition Method Metis Stored Partition Count 2 Done. 8.Displa y the mesh ( Figur e 43.10: The P artitioned ID S et to Zero (p.3079 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3078Parallel P rocessingFigur e 43.10: The P artitioned ID S et t o Zero 9.This time , set the Set S elec ted Z ones and Regist ers t o Partition ID to 1 and click the c orresponding butt on.This displa ys a r eport in the ANSY S Fluen t console . 10.Click the Use S tored P artitions butt on t o mak e the new par titions v alid and t o migr ate the par titions to the c omput e-no des. 11.Displa y the mesh ( Figur e 43.11: The P artitioned ID S et to 1 (p.3079 )). Notice no w tha t the par tition app ears in a diff erent location as sp ecified b y your par tition ID . Figur e 43.11: The P artitioned ID S et t o 1 Imp ortant Although this e xample demonstr ates setting selec ted r egist ers t o sp ecific par tition IDs in parallel, it c an b e similar ly applied in ser ial. 43.5.4.1.2. Partitioning Within Z ones or R egist ers The abilit y to restrict par titioning t o cell z ones or r egist ers giv es y ou the fle xibilit y to apply diff erent partitioning str ategies t o subr egions of a domain. For e xample , if y our geometr y consists of a c yl- indr ical plenum c onnec ted t o a r ectangular duc t, you ma y want to par tition the plenum using the Cylindr ical A xes metho d, and the duc t using the Cartesian A xes metho d. 3079Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Mesh P artitioning and L oad B alancingIf the plenum and the duc t are contained in t wo diff erent cell z ones , you c an selec t one a t a time and p erform the desir ed par titioning , as descr ibed in Using the P artitioning and L oad B alancing Dialog Box (p.3071 ). If the y are not in t wo diff erent cell z ones , you c an cr eate a c ell r egist er (basic ally a list of c ells) f or each r egion using the func tions tha t are used t o mar k cells f or adaption. These func tions allo w you t o mar k cells based on ph ysical lo cation, cell v olume , gradien t or iso value of a particular v ariable , and other par amet ers. See Adapting the M esh (p.2705 ) for inf ormation ab out mar king c ells f or adaption. Using C ell R egist ers (p.2758 ) provides inf ormation ab out cr eating c ell r e- gisters. Onc e you ha ve created a c ell r egist er, you c an par tition within it as descr ibed in Example of Setting S elec ted C ell R egist ers t o Specified P artition IDs (p.3077 ). Imp ortant Note tha t par titioning within z ones or r egist ers is not a vailable when Metis is selec ted as the par tition Metho d. For d ynamic mesh applic ations , ANSY S Fluen t stores the par tition metho d used t o par tition the r e- spective zone .Therefore, if repar titioning is done , ANSY S Fluen t uses the same metho d tha t was used t o par tition the mesh. 43.5.4.1.3. Reporting D uring P artitioning As the mesh is par titioned , information ab out the par titioning pr ocess will b e displa yed in the c onsole . By default , the numb er of par titions cr eated, the time r equir ed f or the par titioning , and the minimum and maximum c ell, face, interface, and fac e-ratio v ariations will b e displa yed (f or details , see Inter- preting P artition S tatistics (p.3089 )). If you incr ease the Rep orting Verb osit y to 2 fr om the default value of 1, the par tition metho d used , the par tition ID , numb er of c ells, faces, and in terfaces, and the r atio of in terfaces to fac es for each par tition will also b e displa yed in the c onsole . If you decr ease the Rep orting Verb osit y to 0, only the numb er of par titions cr eated and the time r equir ed f or the partitioning will b e reported. You c an r equest a p ortion of this r eport to be displa yed again af ter the par titioning is c omplet ed. When y ou click the Print Active Partitions or Print Stored P artitions butt on in the ser ial or par allel solv er, ANSY S Fluen t will displa y the par tition ID , numb er of c ells, faces, and in terfaces, and the r atio of in terfaces to fac es for each ac tive or st ored par tition in the c onsole . In addition, it will displa y the minimum and maximum c ell, face, interface, and fac e-ratio v ariations . For details , see Interpreting Partition S tatistics (p.3089 ). Imp ortant Recall tha t to mak e the st ored c ell par titions the ac tive cell par titions y ou must click the Use S tored P artitions butt on.The ac tive cell par tition is used f or the cur rent calcula tion, while the st ored c ell par tition (the last par tition p erformed) is used when y ou sa ve a c ase file. 43.5.4.1.4. Resetting the P artition P aramet ers If you change y our mind ab out y our par tition par amet er settings , you c an easily r etur n to the default settings assigned b y ANSY S Fluen t by click ing on the Default butt on.When y ou click the Default butt on, it will b ecome the Reset butt on.The Reset butt on allo ws you t o retur n to the most r ecently saved settings (tha t is, the v alues tha t were set b efore you click ed on Default ). After e xecution, the Reset butt on will b ecome the Default butt on again. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3080Parallel P rocessing43.5.4.2. Load B alancing A dynamic load balancing c apabilit y is a vailable in ANSY S Fluen t.The pr incipal r eason f or using par- allel pr ocessing is t o reduc e the tur naround time of y our simula tion, which ma y be achie ved b y the following means: •Faster machines , for e xample , fast er CPU, memor y, cache , and c ommunic ation band width b etween the CPU and memor y •Faster in terconnec ts, for e xample , smaller la tency and lar ger band width •Better Load balancing , for e xample , load is e venly distr ibut ed and CPU s are not idled dur ing c alcula tion The first t wo evolve at the pac e of c omput er technolo gy, which is b eyond the sc ope of this do cumen t. The thir d item is r egar ding optimiza tion of a vailable c omputa tion p ower. Here we ar e mainly talk ing about load balancing on dedic ated homo geneous r esour ces, which is of ten the c ase no wadays. If you ar e not using a dedic ated homo geneous r esour ce, you ma y need t o acc oun t for diff erences in CPU sp eeds dur ing par titioning b y sp ecifying a load distr ibution (f or details , see Load D istribu- tion (p.3092 )). On a dedic ated homo geneous sy stem, the k ey for load balancing is ho w to evalua te the c omputa tional requir emen t of each c ell. By default , ANSY S Fluen t assumes tha t each c ell r equir es the same c ompu- tational w ork, but this is of ten not the c ase. For e xample •A he xahedr al cell demands mor e CPU and memor y than a t etrahedr al cell. •A cell with par ticle tr acking will use mor e time than a c ell without par ticle tr acking. •ISAT sp ecies mo del c ells ma y ha ve magnitude diff erences in time usage . To balanc e these diff erences, ideally , the time used in each c ell c ould b e recorded and load balanc e achie ved based on these detailed timing sta tistics . However, this c an b e expensiv e and such lo w le vel timings c an b e unr eliable in an y case. Inst ead, we iden tify f eatures c ausing c omputa tional imbalanc e and r ecord time usage f or these mo dels in aggr egate. For a mor e detailed descr iption of this , refer to Partitioning (p.3071 ) in the discussion of the Weigh ting tab . In addition, the imbalanc e ma y happ en dynamic ally dur ing r un time , for e xample •The mesh ma y be changed b y adaption or mesh mo vemen t. •In unst eady cases , par ticle tr acking ma y mo ve from one r egion t o another r egion. Dynamic load balancing has b een implemen ted f or b etter sc alabilit y of c ases with imbalanc ed ph ys- ical or geometr ical mo dels , ther eby reducing the simula tion time .The implemen tation c onsiders weigh ts fr om these mo dels sc aled b y CPU time usage . Load balancing f or DPM, VOF, cell t ype (numb er of fac es p er cell), and solid z ones c an b e performed . In addition, cell w eigh t based load balancing and machine load distr ibution c an also b e sp ecified (f or details , see Load D istribution (p.3092 )). ANSY S Fluen t tak es the w eigh ts fr om ph ysical mo dels and c onsiders them f or par titioning .The w eigh ts ar e assembled based on the time used b y each ph ysical mo del. For d ynamic load balancing , the load is check ed and balanc ed based on y our sp ecified imbalanc e thr eshold .To apply d ynamic load balancing on the v arious mo dels , click the Dynamic L oad B alancing tab and selec t the r equir ed balancing as follows: 3081Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Mesh P artitioning and L oad B alancingFigur e 43.12: The D ynamic L oad B alancing Tab 1.Enable Physical M odels load balancing dur ing it erations so tha t the load will b e evalua ted f or time usage and w eigh t distr ibution, based on the Interval tha t you pr ovide . If the imbalanc e exceeds the sp ecified Threshold , then r epar titioning will b e performed b y consider ing the selec ted w eigh ts.Physical M odels load balancing will only b e available when y ou ha ve the sp ecific ph ysical mo dels enabled in the c ase. You will b e pr ompt ed t o enable the w eigh ts for those mo dels .When w eigh ts for the ph ysical mo dels are all disabled , you will b e pr ompt ed t o disable Physical M odels load balancing . Note Applying load balancing t oo frequen tly ma y cause p erformanc e degr adation due t o the additional c ost of migr ating c ells f or the new par tition la yout. 2.Enable Dynamic M esh if ther e is an y dynamic mesh mo vemen t. Load balancing , based on the numb er of cells, will b e check ed and balanc ed if the imbalanc e thr eshold is e xceeded .These par allel par titioning options ar e pr ovided b ecause with mesh motion, when lo cal remeshing and smo othing ar e performed , the par tition in terface can b ecome v ery wr inkled and load balanc e ma y det eriorate. By default , the Auto option is selec ted, wher e a p ercentage of in terface fac es and loads ar e aut oma tically tr aced.When this option is selec ted, ANSY S Fluen t aut oma tically det ermines the most appr opriate repar titioning in terval based on v arious simula tion par amet ers. However, sometimes , the fr equenc y of load balancing fr om the Auto option ma y be inadequa te, and then the Interval setting c an b e explicitly set. The Interval setting lets y ou sp ecify the in terval (in time st eps or it erations , respectively) when load balancing is enf orced. When load balancing is not desir ed, you ma y disable Dynamic M esh load balancing . Dynamic M esh load balancing is only a vailable when y ou ha ve dynamic mo dels enabled in y our c ase. Imp ortant Note tha t when d ynamic meshes and lo cal remeshing ar e utiliz ed, updated meshes may be sligh tly diff erent in par allel ANSY S Fluen t (when c ompar ed t o ser ial ANSY S Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3082Parallel P rocessingFluen t or when c ompar ed t o a par allel solution cr eated with a diff erent numb er of comput e no des), resulting in v ery small diff erences in the solutions . 3.Enable Mesh A daption . Any time mesh adaption o ccurs , load balancing , based on the numb er of c ells, will b e check ed and balanc ed if the imbalanc e thr eshold is e xceeded . If problems ar ise in y our c omputa- tions due t o adaption, you c an disable the load balancing f or Mesh A daption . 43.5.5. Mesh P artitioning M etho ds Partitioning the mesh f or par allel pr ocessing has thr ee major goals: •Create par titions with equal numb ers of c ells. •Minimiz e the numb er of par tition in terfaces — tha t is, decr ease par tition b oundar y sur face area. •Minimiz e the numb er of par tition neighb ors. Balancing the par titions (equalizing the numb er of c ells) ensur es tha t each pr ocessor has an equal load and tha t the par titions will b e ready to communic ate at ab out the same time . Since communic ation between par titions c an b e a r elatively time-c onsuming pr ocess, minimizing the numb er of in terfaces can r educ e the time asso ciated with this da ta in terchange . Minimizing the numb er of par tition neighb ors r educ es the chanc es for net work and r outing c ontentions . In addition, minimizing par tition neighb ors is imp ortant on machines wher e the c ost of initia ting message passing is e xpensiv e compar ed to the c ost of sending longer messages .This is esp ecially tr ue f or w orksta tions c onnec ted in a net work. The par titioning schemes in ANSY S Fluen t use bisec tion or METIS algor ithms t o cr eate the par titions , but unlik e other schemes tha t requir e the numb er of par titions t o be a fac tor of t wo, these schemes have no limita tions on the numb er of par titions .You will cr eate as man y par titions as ther e ar e com- puting units (c ores based on pr ocessors and machines) a vailable f or y our simula tion. 43.5.5.1. Partition Metho ds The mesh is par titioned using a bisec tion or METIS algor ithm. The selec ted algor ithm is applied t o the par ent domain, and then r ecursiv ely applied t o the sub domains . For e xample , to divide the mesh into four par titions with a bisec tion metho d, Fluen t will bisec t the en tire (par ent) domain in to two child domains , and then r epeat the bisec tion f or each of the child domains , yielding f our par titions in total. To divide the mesh in to thr ee par titions with a bisec tion metho d, Fluen t will “bisec t” the parent domain t o cr eate two par titions—one appr oxima tely t wice as lar ge as the other—and then bisec t the lar ger child domain again t o cr eate thr ee par titions in t otal. METIS uses gr aph par titioning techniques tha t gener ally pr ovide mor e optimal par titions than the geometr ic metho ds. The mesh c an b e par titioned using one of the algor ithms list ed b elow.The most efficien t choic e is problem-dep enden t, so y ou c an tr y diff erent metho ds un til you find the one tha t is b est f or y our problem. See Guidelines f or P artitioning the M esh (p.3071 ) for recommended par titioning str ategies . Cartesian A xes bisec ts the domain based on the C artesian c oordina tes of the c ells (see Figur e 43.13: Partitions C reated with the C artesian A xes M etho d (p.3085 )). It bisec ts the par ent domain and all subsequen t child sub domains perpendicular t o the c oordina te dir ection with the longest e xtent of the ac tive domain. It is of ten r eferred to as c oordina te bisec tion. 3083Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Mesh P artitioning and L oad B alancingCartesian S trip uses c oordina te bisec tion but r estricts all bisec tions t o the C artesian dir ection of longest e xtent of the parent domain (see Figur e 43.14: Partitions C reated with the C artesian S trip or C artesian X-C oordina te Metho d (p.3086 )).You c an of ten minimiz e the numb er of par tition neighb ors using this appr oach. Cartesian X-, Y-, Z-C oordina te bisec ts the domain based on the selec ted C artesian c oordina te. It bisec ts the par ent domain and all subsequen t child sub domains p erpendicular t o the sp ecified c oordina te dir ection. (See Figur e 43.14: Par- titions C reated with the C artesian S trip or C artesian X-C oordina te Metho d (p.3086 ).) Cartesian R A xes bisec ts the domain based on the shor test r adial distanc e from the c ell c enters t o tha t Cartesian axis ( , , or ) whiche ver pr oduces the smallest in terface siz e.This metho d is a vailable only in 3D . Cartesian R X-, RY-, RZ-C oordina te bisec ts the domain based on the shor test r adial distanc e from the c ell c enters t o the selec ted C artesian axis ( , , or ).These metho ds ar e available only in 3D . Cylindr ical A xes bisec ts the domain based on the c ylindr ical coordina tes of the c ells.This metho d is a vailable only in 3D . Cylindr ical R-, Theta-, Z-C oordina te bisec ts the domain based on the selec ted c ylindr ical coordina te.These metho ds ar e available only in 3D. Metis uses the METIS sof tware pack age f or par titioning ir regular gr aphs , develop ed b y Karypis and K umar at the U niversit y of M innesota and the A rmy HPC R esear ch C enter. It uses a multile vel appr oach in which the v ertices and edges on the fine gr aph ar e coalesc ed t o form a c oarse gr aph. The coarse gr aph is par titioned , and then unc oarsened back t o the or iginal gr aph. During c oarsening and unc oarsening , algor ithms ar e applied t o permit high-qualit y par titions . METIS r outines c an handle par titioning with mo del-w eigh ted multiple c onstr aints: when aut oma tically par titioning , solid c ell z ones ar e weigh ted with a default v alue of 0.1 r elative to the fluid c ell w eigh ting; when manually par titioning , you c an c ontrol w eigh ting f or c ells, solid c ell z ones ,VOF, DPM, and ISA T table lo okup (as descr ibed in Partitioning (p.3071 )). Detailed inf ormation ab out METIS c an b e found in [55] (p.4008 ) and [56] (p.4008 ). Imp ortant If you cr eate non-c onformal in terfaces, and gener ate vir tual p olygonal fac es, your METIS par tition c an cr oss non-c onformal in terfaces b y using the c onnec tivit y of the virtual p olygonal fac es.This impr oves load balancing f or the par allel solv er and minim- izes c ommunic ation b y decr easing the numb er of par tition in terface cells. Polar A xes bisec ts the domain based on the p olar c oordina tes of the c ells (see Figur e 43.17: Partitions C reated with the P olar A xes or P olar Theta-C oordina te Metho d (p.3087 )).This metho d is a vailable only in 2D . Polar R-C oordina te, Polar Theta-C oordina te bisec ts the domain based on the selec ted p olar c oordina te (see Figur e 43.17: Partitions C reated with the Polar A xes or P olar Theta-C oordina te Metho d (p.3087 )).These metho ds ar e available only in 2D . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3084Parallel P rocessingPrincipal A xes bisec ts the domain based on a c oordina te frame aligned with the pr incipal ax es of the domain (see Figur e 43.15: Partitions C reated with the P rincipal A xes M etho d (p.3086 )).This r educ es to Cartesian bisec tion when the pr incipal ax es ar e aligned with the C artesian ax es.The algor ithm is also r eferred t o as momen t, iner tial, or momen t-of-iner tia par titioning . This is the default bisec tion metho d in ANSY S Fluen t. Principal S trip uses momen t bisec tion but r estricts all bisec tions t o the pr incipal axis of longest e xtent of the par ent domain (see Figur e 43.16: Partitions C reated with the P rincipal S trip or P rincipal X-C oordina te Meth- od (p.3087 )).You c an of ten minimiz e the numb er of par tition neighb ors using this appr oach. Principal X-, Y-, Z-C oordina te bisec ts the domain based on the selec ted pr incipal c oordina te (see Figur e 43.16: Partitions C reated with the P rincipal S trip or P rincipal X-C oordina te Metho d (p.3087 )). Spher ical A xes bisec ts the domain based on the spher ical coordina tes of the c ells.This metho d is a vailable only in 3D . Spher ical R ho-, Theta-, Phi-C oordina te bisec ts the domain based on the selec ted spher ical coordina te.These metho ds ar e available only in 3D . Figur e 43.13: Partitions C reated with the C artesian A xes M etho d 3085Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Mesh P artitioning and L oad B alancingFigur e 43.14: Partitions C reated with the C artesian S trip or C artesian X-C oordina te M etho d Figur e 43.15: Partitions C reated with the P rincipal A xes M etho d Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3086Parallel P rocessingFigur e 43.16: Partitions C reated with the P rincipal S trip or P rincipal X-C oordina te M etho d Figur e 43.17: Partitions C reated with the P olar A xes or P olar Theta-C oordina te M etho d 43.5.5.2. Optimizations Additional optimiza tions c an b e applied t o impr ove the qualit y of the mesh par titions .The heur istic of bisec ting p erpendicular t o the dir ection of longest domain e xtent is not alw ays the b est choic e for cr eating the smallest in terface boundar y. A pr e-testing op eration (f or details , see Pretesting (p.3088 )) can b e applied t o aut oma tically cho ose the b est dir ection b efore par titioning . In addition, the f ollowing iterative optimiza tion schemes e xist: 3087Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Mesh P artitioning and L oad B alancingSmooth attempts t o minimiz e the numb er of par tition in terfaces b y sw apping c ells b etween par titions .The scheme tr averses the par tition b oundar y and giv es c ells t o the neighb oring par tition if the in terface boundar y sur face area is decr eased . (See Figur e 43.18: The S mooth Optimiza tion Scheme (p.3088 ).) Merge attempts t o elimina te or phan clust ers fr om each par tition. An or phan clust er is a gr oup of c ells with the common f eature tha t each c ell within the gr oup has a t least one fac e tha t coincides with an in terface boundar y. (See Figur e 43.19: The M erge Optimiza tion Scheme (p.3088 ).) Or phan clust ers c an degr ade multigr id p erformanc e and lead t o lar ge c ommunic ation c osts . Figur e 43.18: The S mooth Optimiza tion Scheme Figur e 43.19: The M erge Optimiza tion Scheme In gener al, the S mooth and M erge schemes ar e relatively ine xpensiv e optimiza tion t ools. 43.5.5.3. Pretesting If you cho ose the Principal A xes or Cartesian A xes metho d, you c an impr ove the bisec tion b y testing different dir ections b efore performing the ac tual bisec tion. If you cho ose not t o use pr etesting (the default), ANSY S Fluen t will p erform the bisec tion p erpendicular t o the dir ection of longest domain extent. If pretesting is enabled , it will o ccur aut oma tically when y ou click the Partition butt on in the Parti- tioning and L oad B alancing D ialog Box (p.3887 ), or when y ou r ead in the mesh if y ou ar e using aut o- matic par titioning .The bisec tion algor ithm will t est all c oordina te dir ections and cho ose the one which yields the f ewest par tition in terfaces for the final bisec tion. Note tha t using pr etesting will incr ease the time r equir ed f or par titioning . For 2D pr oblems par titioning will tak e 3 times longer than without pr etesting , and f or 3D pr oblems it will tak e 4 times longer . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3088Parallel P rocessing43.5.5.4. Using the P artition F ilter As not ed ab ove, you c an use the METIS par titioning metho d thr ough a filt er in addition t o within the Auto Partition M esh and Partitioning and L oad B alancing dialo g boxes.To perform METIS par ti- tioning on an unpar titioned mesh, use the File/Imp ort/Partition/M etis ... ribbon tab it em. File → Imp ort → Partition → Metis ... ANSY S Fluen t will use the METIS par titioner t o par tition the mesh, and then r ead the par titioned mesh. The numb er of par titions will b e equal t o the numb er of pr ocesses .You c an then pr oceed with the mo del definition and solution. Imp ortant Direct imp ort to the par allel solv er thr ough the par tition filt er requir es tha t the host machine has enough memor y to run the filt er for the sp ecified mesh. If not , you must r un the filt er on a machine tha t do es ha ve enough memor y.You c an either star t the par allel solv er on the machine with enough memor y and r epeat the pr ocess descr ibed ab ove, or r un the filter manually on the new machine and then r ead the par titioned mesh in to the par allel solv er on the host machine . To manually par tition a mesh using the par tition filt er, enter the f ollowing c ommand: utility partition input_filename par tition_c ount output_filename wher e input_filename is the filename f or the mesh t o be par titioned ,par tition_c ount is the numb er of par titions desir ed, and output_filename is the filename f or the par titioned mesh. You c an then r ead the par titioned mesh in to Fluen t (using the standar d File/Read/C ase... ribbon tab it em) and pr oceed with the mo del definition and solution. When the File/Imp ort/Partition/M etis ... ribbon tab it em is used t o imp ort an unpar titioned mesh into the par allel solv er, the METIS par titioner par titions the en tire mesh. You ma y also par tition each cell z one individually , using the File/Imp ort/Partition/M etis Z one ... ribbon tab it em. File → Imp ort → Partition → Metis Z one ... This metho d can b e useful f or balancing the w ork load f or c ases tha t ha ve few c ell z ones . 43.5.6. Check ing the P artitions After par titioning a mesh, you should check the par tition inf ormation and e xamine the par titions graphic ally. 43.5.6.1. Interpr eting P artition Statistics You c an r equest a r eport to be displa yed af ter par titioning (either aut oma tic or manual) is c omplet ed. Click the Print Active Partitions or Print Stored P artitions butt on in the Partitioning and L oad Balancing dialo g box. ANSY S Fluen t distinguishes b etween t wo cell par tition schemes: the ac tive cell par titions and the stored c ell par titions . Initially , both ar e set t o the c ell par titions tha t were established up on r eading the c ase file . If you r e-par tition the mesh using the Partitioning and L oad B alancing dialo g box, the 3089Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Mesh P artitioning and L oad B alancingnew par titions will b e referred t o as the st ored c ell par titions .To mak e them the ac tive cell par titions , you must click the Use S tored P artitions butt on in the Partitioning and L oad B alancing dialo g box in the par allel v ersion of ANSY S Fluen t.The ac tive cell par titions ar e used f or the cur rent calcula tion, while the st ored c ell par titions (det ermined fr om the last par titioning p erformed) ar e used when y ou save a c ase file .This distinc tion is made mainly t o allo w you t o par tition a c ase on one machine or network of machines and solv e it on a diff erent one .Thanks t o the t wo separ ate par titioning schemes , you c ould use the par allel solv er with a c ertain numb er of c omput e no des t o sub divide a mesh in to an arbitr ary diff erent numb er of par titions , suitable f or a diff erent par allel machine , save the c ase file , and then load it in to the designa ted machine . The output gener ated when y ou pr int the par titions c onsists of tabula ted inf ormation ab out the active or st ored par titioning scheme . A typic al output f or a mesh with 4 par titions is as f ollows: >> 4 Active Partitions: P Cells I-Cells Cell Ratio Faces I-Faces Face Ratio Neighbors Load 0 3520 142 0.040 11399 195 0.017 1 1 1 3298 115 0.035 10678 151 0.014 1 1 2 3451 305 0.088 11404 372 0.033 2 1 3 3583 332 0.093 11586 416 0.036 2 1 ---------------------------------------------------------------------- Collective Partition Statistics: Minimum Maximum Total ---------------------------------------------------------------------- Cell count 3298 3583 13852 Mean cell count deviation -4.8% 3.5% Partition boundary cell count 115 332 894 Partition boundary cell count ratio 3.5% 9.3% 6.5% Face count 10678 11586 44500 Mean face count deviation -5.2% 2.8% Partition boundary face count 151 416 567 Partition boundary face count ratio 1.4% 3.6% 1.3% Partition neighbor count 1 2 ---------------------------------------------------------------------- Partition Method Metis Stored Partition Count 4 The first table in the output displa ys per-par tition sta tistics of in terest: P the par tition ID Cells the numb er of c ells in the par tition I-Cells the numb er of in terface cells in the par tition (tha t is, cells tha t lie on the par tition in terfaces) Cell Ratio the r atio of in terface cells t o total c ells f or the par tition Faces the numb er of fac es in the par tition I-Faces the numb er of in terface fac es in the par tition (tha t is, faces tha t lie on par tition in terfaces) Face Ratio the r atio of in terface fac es to total fac es for the par tition Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3090Parallel P rocessingNeighbors the numb er of neighb or par titions Load the desir ed r elative load on this no de in pr oportion t o the other no des. See Load D istribution (p.3092 ) for details . Note tha t par tition IDs c orrespond dir ectly t o comput e no de IDs when a c ase file is r ead in to the parallel solv er.When the numb er of par titions in a c ase file is lar ger than the numb er of c omput e nodes, but is e venly divisible b y the numb er of c omput e no des, then the distr ibution is such tha t partitions with IDs to are mapp ed on to comput e no de 0, par titions with IDs to onto comput e no de 1, and so on, wher e is equal t o the r atio of the numb er of par titions t o the numb er of c omput e no des. The sec ond table in the output displa ys Minimum ,Maximum , and (wher e applic able) Total values for v arious par tition sta tistics: Cell Count the numb er of c ells in the par titions (c orresponding t o Cells in the p er-par tition table) Mean cell count deviation the de viation of an individual par tition c ell c oun t from the mean par tition c ell c oun t Partition boundary cell count the numb er of c ells tha t lie on par tition in terfaces (c orresponding t o I-Cells in the p er-par tition table) Partition boundary cell count ratio the r atio of the numb er of c ells tha t lie on par tition in terfaces to the t otal numb er of c ells in the partition (c orresponding t o Cell Ratio in the p er-par tition table) Face Count the numb er of fac es in the par titions (c orresponding t o Faces in the p er-par tition table) Mean face count deviation the de viation of an individual par tition fac e coun t from the mean par tition fac e coun t Partition boundary face count the numb er of fac es tha t lie on par tition in terfaces (c orresponding t o I-Faces in the p er-par tition table) Partition boundary face count ratio the r atio of the numb er of fac es tha t lie on par tition in terfaces to the t otal numb er of fac es in the partition (c orresponding t o Face Ratio in the p er-par tition table) Partition neighbor count the numb er of neighb ors f or a giv en par tition (c orresponding t o Neighbors in the p er-par tition table) Finally , the Partition Method and Stored Partition Count are displa yed. Your aim is t o minimiz e the Maximum value of the Partition boundary face count ratio , while main taining a balanc ed load . For a giv en mesh, the Mean cell count deviation is a 3091Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Mesh P artitioning and L oad B alancingmeasur e of the maximum load imbalanc e for a metho d. If the sta tistics ar e not sa tisfac tory for a problem, you c an tr y one of the other par titioning metho ds. If ther e is an o verset mesh f or which the solution has b een initializ ed, an additional par tition table with solv e and dead c ells is included in the par titioning r eport (see Overset C ell M arks (p.787) for the definitions of such c ells): >> Overset partition statistics: P Cells Solve-cells Dead-cells Ext donors 0 66 53 4 12 1 66 55 4 10 ---------------------------------------------------------------------- Overset Partition Statistics: Minimum Maximum Total ---------------------------------------------------------------------- Cell count 66 66 132 Mean cell count deviation 0.0% 0.0% Solve cell count 53 55 108 Mean solve cell count deviation -1.9% 1.9% Dead cell count 4 4 8 Mean dead cell count deviation 0.0% 0.0% Ext donors 10 12 22 ---------------------------------------------------------------------- Partition Method Metis Stored Partition Count 2 43.5.6.2. Examining P artitions Gr aphic ally To fur ther aid in terpretation of the par tition inf ormation, you c an dr aw contours of the mesh par titions (see the figur es in Partition M etho ds (p.3083 )). Results → Graphics → Contours Edit... To displa y the ac tive cell par tition or the st ored c ell par tition (which w ere descr ibed ab ove), selec t Active Cell P artition or Stored C ell P artition in the Cell Inf o... categor y of the Contours O f drop- down list , and tur n off the displa y of Node Values (for details , see Displa ying C ontours and P ro- files (p.2784 ) for inf ormation ab out displa ying c ontours). Imp ortant If you ha ve not alr eady done so in the setup of y our pr oblem, you must p erform a solution initializa tion in or der t o use the Contours dialo g box. 43.5.7. Load D istribution If the sp eeds of the pr ocessors tha t will b e used f or a par allel c alcula tion diff er signific antly, you c an specify a load distr ibution f or par titioning , using the load-distribution text command . parallel → partition → set → load-distribution For e xample , if y ou will b e solving on thr ee c omput e no des, and one machine is t wice as fast as the other t wo, then y ou ma y want to assign t wice as man y cells t o the first machine as t o the others (tha t Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3092Parallel P rocessingis, a load v ector of (2 1 1)). During subsequen t mesh par titioning , par tition 0 will end up with t wice as man y cells as par titions 1 and 2. For this e xample , you need t o star t up ANSY S Fluen t such tha t comput e no de 0 is the fast machine , sinc e par tition 0, with t wice as man y cells as the others , will b e mapp ed on to comput e no de 0. Altern- atively, in this situa tion, you c ould enable the load balancing f eature (descr ibed in Load B alan- cing (p.3081 )) to ha ve ANSY S Fluen t aut oma tically a ttempt t o disc ern an y diff erence in load among the comput e no des. 43.5.8. Troublesho oting When r unning a c alcula tion using par allel ANSY S Fluen t, you ma y enc oun ter a w arning message in the c onsole tha t reports pr oblems r elated t o the par titioning .The f ollowing is an e xample of such a warning: #AMG# Warning: The global matrix size (1273286) is too large, and may adversely affect the parallel performance. See the ANSYS Fluent User's Guide for information on troubleshooting partitioning issues. The f ollowing ar e possible r easons f or par titioning pr oblems , along with r ecommenda tions f or reducing them: •The pr esenc e of solid z ones ma y cause a par tition t o ha ve a v ery small amoun t of fluid c ells, or none at all. To avoid this , it is r ecommended tha t you use the Metis metho d with aut oma tic or manual partitioning; for the la tter, you must ensur e tha t Solid Z ones weigh ting and mo del-w eigh ted par ti- tioning ar e enabled , with a suitable Value for the solid-t o-fluid c ell w eigh ting (f or e xample ,0.1 ). •A par tition ma y ha ve a small numb er of c ells if y ou ha ve set up a load distr ibution f or par titioning . Such settings should b e disabled , by using the load-distribution text command (descr ibed in Load D istri- bution (p.3092 )) and en tering a v alue of 1 for each of the pr eviously defined par titions . •Some mo del settings (f or e xample , shell c onduc tion) c an enc apsula te some c ells, which ma y cause difficulties with the c oarsening pr ocess.To remed y this situa tion, you c an either tr y a diff erent par titioning metho d, or y ou c an enable the global c oarsening check ing cr iteria with the f ollowing r pvar setting: (rpsetvar 'amg/parallel/global-check-coarsening? #t) •Coupled w alls ar e enc apsula ted as par t of the shell c onduc tion mo del and S2S mo del. If you ha ve partitioning pr oblems , you c an tr y reverting t o the enc apsula tion r outine used pr ior t o version 16.0 by disabling the enhanc ed enc apsula tion: define → models → shell-conduction → enhanced-encapsulation? 43.6. Using G ener al P urpose G raphics P rocessing U nits (GPGPU s) With the A lgebr aic M ultigr id (AMG) S olver You c an acc elerate the A lgebr aic M ultigr id (AMG) solv er inside F luen t using G ener al Purpose G raphics Processing U nits (GPGPU s) if suitable har dware is a vailable on y our c omput e machines .When enabled , you c an use GPGPU acc eleration f or AMG c omputa tions in a F luen t session on linear sy stems with up to 5 c oupled equa tions . Using GPGPU s requir es HPC lic enses . Licensing details c an b e found in HPC Li- censing in the ANSY S, Inc . Lic ensing G uide . 3093Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using G ener al Purpose G raphics P rocessing U nits (GPGPU s) With the A lgebr aic Multigr id (AMG) S olver43.6.1. Requir emen ts GPU s tha t are supp orted in the cur rent release ar e posted on the Platform Supp ort sec tion of the ANSY S Websit e. When star ting the par allel F luen t session the f ollowing c onditions must b e met: •The numb er of solv er pr ocesses p er machine must b e equal on all machines . •The numb er solv er pr ocesses p er machine must b e evenly divisible b y the sp ecified numb er of GPGPU s per machine . 43.6.2. Limita tions GPGPU acc eleration is subjec t to the f ollowing limita tions: •When using F luen t in Workbench, the numb er of GPGPU s cannot b e set thr ough: –Properties of S etup C ells –Properties of S olution C ells –Properties of S olution C ells thr ough RSM up date –Properties of P aramet er Sets thr ough RSM up date •GPGPU acc eleration will not b e used in the f ollowing c ases: –The p opula tion balanc e mo del is ac tive. –The E uler ian multiphase mo del is ac tive. –The sy stem has mor e than 5 c oupled equa tions . 43.6.3. Using and M anaging GPGPU s In or der t o use GPGPU s, you must sp ecify in the F luen t Launcher or with the -gpgpu= ngpgpus command line option ho w man y GPGPU s are to be used p er machine (not e tha t when launching in serial, the c ommand line option is the only a vailable w ay to sp ecify the GPGPU s). For details , refer to the f ollowing sec tions: Starting P arallel ANSY S Fluen t Using F luen t Launcher (p.3047 ) Starting P arallel ANSY S Fluen t on a Windo ws System U sing C ommand Line Options (p.3058 ) Starting P arallel ANSY S Fluen t on a Linux S ystem (p.3063 ) Onc e the F luen t session is r unning , you c an view and/or selec t the a vailable GPGPU s on the sy stem using the f ollowing TUI c ommands: parallel/gpgpu/show displa y the a vailable GPGPU s on the sy stem. parallel/gpgpu/select selec t the GPGPU s to use . Note tha t you c an only selec t up t o the numb er of GPGPU s tha t you sp ecified on the c ommand line or in the F luen t Launcher when star ting the session. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3094Parallel P rocessingBy default , GPGPU acc eleration is applied aut oma tically t o coupled sy stems and not t o sc alar sy stems because sc alar sy stems t ypic ally ar e not as c omputa tionally e xpensiv e. However, if desir ed y ou c an enable/disable GPGPU acc eleration of the AMG solv er for c oupled and sc alar sy stems in the f ollowing TUI menu: solve/set/amg-options/amg-gpgpu-options/ The menu c ontains c ommands f or each supp orted equa tion t ype allo wing y ou t o enable/disable GPGPU acceleration, cho ose b etween AMG and FGMRES solv ers, and sp ecify v arious solv er options . 43.7. Controlling the Threads You c an c ontrol the maximum numb er of thr eads on each machine b y using the Thread C ontrol dialo g box (Figur e 43.21: The P arallel C onnec tivit y Dialog Box (p.3096 )). Parallel → Gener al → Thread C ontrol... Figur e 43.20: The Thread C ontrol D ialo g Box You ha ve the f ollowing options when using the Thread C ontrol dialo g box: •Numb er of N ode P rocesses on M achine This is the default option. When this option is chosen, the maximum numb er of thr eads on each machine is equal t o the numb er of ANSY S Fluen t no de pr ocesses on each machine . •Numb er of C ores on M achine When this option is chosen, the maximum numb er of thr eads on each machine is equal t o the numb er of c ores on the machine . ANSY S Fluen t obtains the numb er of c ores fr om the OS. This ma y be applic able when the multi-thr eaded par t of the c alcula tion is domina ting the c omputa tion time , and the c ontinuous phase c alcula tion is r elatively small, and y ou w ant to tak e full ad vantage of the computa tion r esour ces. For e xample , if y ou ha ve a v ery small c ase with r egar d to the numb er of c ells, but a lar ge numb er of par ticles t o be tracked, you ma y want to spa wn one ANSY S Fluen t no de pr ocess on each machine , but use the maximum numb er of c ores in or der t o get a go od overall p erformanc e. •Fixed N umb er When this option is chosen, you ma y sp ecify the maximum numb er of thr eads tha t can b e spa wned on each machine in the numb er-en try box below Fixed N umb er.This ma y only b e applic able when 3095Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Controlling the Threadsyou w ant to ha ve fine c ontrol of the numb er of thr eads on each machine; it is not r ecommended in gener al. 43.8. Check ing N etwork Connec tivit y For an y comput e no de, you c an pr int net work connec tivit y inf ormation tha t includes the hostname , architecture, process ID , and ID of the selec ted c omput e no de and all machines c onnec ted t o it. The ID of the selec ted c omput e no de is mar ked with an ast erisk. The ID f or the ANSY S Fluen t host pr ocess is alw ays host .The c omput e no des ar e numb ered sequen tially starting fr om node-0 . All comput e no des ar e complet ely c onnec ted. In addition, comput e no de 0 is connec ted t o the host pr ocess. To obtain c onnec tivit y inf ormation f or a c omput e no de, you c an use the Parallel C onnec tivit y Dialog Box (p.3879 ) (Figur e 43.21: The P arallel C onnec tivit y Dialog Box (p.3096 )). Parallel → Network → Connec tivit y... Figur e 43.21: The P arallel C onnec tivit y D ialo g Box Indic ate the c omput e no de ID f or which c onnec tivit y inf ormation is desir ed in the Comput e Node field , and then click the Print butt on. Sample output f or c omput e no de 0 is sho wn b elow: ----------------------------------------------------------------------------------------------- ID Hostname Core O.S. PID Vendor ----------------------------------------------------------------------------------------------- n5 host25 2/64 Linux-64 18909 AMD Opteron(tm) 6278 n2 host25 1/64 Linux-64 18908 AMD Opteron(tm) 6278 n4 host24 2/64 Linux-64 32939 AMD Opteron(tm) 6278 n1 host24 1/64 Linux-64 32938 AMD Opteron(tm) 6278 host host23 - Linux-64 38427 AMD Opteron(tm) 6278 n3 host23 2/64 Linux-64 38755 AMD Opteron(tm) 6278 n0* host23 1/64 Linux-64 38754 AMD Opteron(tm) 6278 43.9. Check ing and Impr oving P arallel P erformanc e Fluen t off ers se veral tools t o help y ou optimiz e the p erformanc e of y our par allel c omputa tions .You can check the utiliza tion of y our har dware using the par allel check f eature.To det ermine ho w w ell the parallel solv er is w orking, you c an measur e computa tion and c ommunic ation times , and the o verall parallel efficienc y, using the p erformanc e met er.You c an also c ontrol the amoun t of c ommunic ation between c omput e no des in or der t o optimiz e the par allel solv er, and tak e ad vantage of the aut oma tic load balancing f eature of ANSY S Fluen t. Information ab out check ing and impr oving par allel p erformanc e is pr ovided in the f ollowing sec tions: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3096Parallel P rocessing43.9.1. Parallel C heck 43.9.2. Check ing P arallel P erformanc e 43.9.3. Optimizing the P arallel S olver 43.9.4. Clearing the Linux F ile C ache B uffers 43.9.1. Parallel C heck You c an use the Check command in the Parallel ribbon tab t o check v arious fac tors tha t aff ect par allel performanc e. Checks ar e performed t o iden tify the f ollowing issues: •CPU c ores ar e overloaded •CPU clo ck is thr ottled •System memor y usage is t oo high •A fast er in terconnec t is a vailable •Partitions ar e imbalanc ed (if a v alid mesh is loaded) 43.9.2. Check ing P arallel P erformanc e The p erformanc e met er allo ws you t o report the w all clo ck time elapsed dur ing a c omputa tion, as w ell as message-passing sta tistics . Since the p erformanc e met er is alw ays enabled , you c an acc ess the statistics b y displa ying them af ter the c omputa tion is c omplet ed.To view the cur rent sta tistics , click Usage in the Parallel ribbon tab ( Timer group b ox). Parallel → Timer → Usage Performanc e sta tistics will b e displa yed in the c onsole . To clear the p erformanc e met er so tha t you c an elimina te past sta tistics fr om the futur e report, click Reset in the Parallel ribbon tab ( Timer group b ox). Parallel → Timer → Reset The f ollowing e xample demonstr ates ho w the cur rent par allel sta tistics ar e displa yed in the c onsole: Performance Timer for 1 iterations on 4 compute nodes Average wall-clock time per iteration: 4.901 sec Global reductions per iteration: 408 ops Global reductions time per iteration: 0.000 sec (0.0%) Message count per iteration: 801 messages Data transfer per iteration: 9.585 MB LE solves per iteration: 12 solves LE wall-clock time per iteration: 2.445 sec (49.9%) LE global solves per iteration: 27 solves LE global wall-clock time per iteration: 0.246 sec (5.0%) AMG cycles per iteration: 64 cycles Relaxation sweeps per iteration: 4160 sweeps Relaxation exchanges per iteration: 920 exchanges Total wall-clock time: 4.901 sec A descr iption of the par allel sta tistics is as f ollows: 3097Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Check ing and Impr oving P arallel P erformanc e•Average wall-clock time per iteration descr ibes the a verage r eal (w all clo ck) time p er it er- ation. •Global reductions per iteration descr ibes the numb er of global r educ tion op erations (such as v ariable summa tions o ver all pr ocesses). This r equir es c ommunic ation among all pr ocesses . A global r educ tion is a c ollec tive op eration o ver all pr ocesses f or the giv en job tha t reduc es a v ector quan tity (the length giv en b y the numb er of pr ocesses or no des) t o a sc alar quan tity (for e xample , taking the sum or maximum of a par ticular quan tity).The numb er of global r educ tions c annot b e calcula ted fr om an y other r eadily k nown quan tities .The numb er is gener ally dep enden t on the al- gorithm b eing used and the pr oblem b eing solv ed. •Global reductions time per iteration descr ibes the time p er it eration f or the global r educ tion operations . •Message count per iteration descr ibes the numb er of messages sen t between all pr ocesses p er iteration. This is imp ortant with r egar d to communic ation la tency, esp ecially on high-la tency interconnec ts. A message is defined as a single p oint-to-point, send-and-r eceive op eration b etween an y two pr o- cesses .This e xcludes global, collec tive op erations such as global r educ tions . In t erms of domain decomp osition, a message is passed fr om the pr ocess go verning one sub domain t o a pr ocess go v- erning another (usually adjac ent) sub domain. The message c oun t per it eration is usually dep enden t on the algor ithm b eing used and the pr oblem being solv ed.The message c oun t and the numb er of messages tha t are reported ar e totals f or all processors . The message c oun t provides some insigh t into the impac t of c ommunic ation la tency on par allel performanc e. A higher message c oun t indic ates tha t the par allel p erformanc e ma y be mor e ad versely affected if a high-la tency interconnec t is b eing used . Ether net has a higher la tency than Infiniband . Therefore, a high message c oun t will mor e ad versely aff ect performanc e with E ther net than with Infiniband . To check the la tency of the o verall clust er in terconnec t, refer to Check ing La tency and B and- width (p.3099 ). •Data transfer per iteration descr ibes the amoun t of da ta communic ated b etween pr ocessors per it eration. This is imp ortant with r espect to interconnec t band width. Data tr ansf er p er it eration is usually dep enden t on the algor ithm b eing used and the pr oblem b eing solv ed.This numb er gener ally incr eases with incr eases in pr oblem siz e, numb er of par titions , and physics c omple xity. The da ta tr ansf er p er it eration ma y pr ovide some insigh t into the impac t of c ommunic ation band width (speed) on par allel p erformanc e.The pr ecise impac t is of ten difficult t o quan tify b ecause it is de- penden t on man y things including: ratio of da ta tr ansf er to calcula tions , and r atio of c ommunic ation band width t o CPU sp eed.The unit of da ta tr ansf er is a b yte. To check the band width of the o verall clust er in terconnec t, refer to Check ing La tency and B and- width (p.3099 ). •LE solves per iteration descr ibes the numb er of linear sy stems b eing solv ed p er it eration. This numb er is dep enden t on the ph ysics (non-r eacting v ersus r eacting flo w) and the algor ithms (pr essur e- Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3098Parallel P rocessingbased v ersus densit y-based solv er), but is indep enden t of mesh siz e. For the pr essur e-based solv er, this is usually the numb er of tr ansp ort equa tions b eing solv ed (mass , momen tum, ener gy, and so on). •LE wall-clock time per iteration descr ibes the time (w all-clo ck) sp ent doing linear equa tion solv ers (tha t is, multigr id). •LE global solves per iteration descr ibes the numb er of solutions on the c oarsest le vel of the AMG solv er wher e the en tire linear sy stem has b een pushed t o a single pr ocessor (n0).The sy stem is pushed to a single pr ocessor t o reduc e the c omputa tion time dur ing the solution on tha t level. Scaling gener ally is not ad versely aff ected b ecause the numb er of unk nowns is small on the c oarser le vels. •LE global wall-clock time per iteration descr ibes the time (w all-clo ck) p er it eration f or the linear equa tion global solutions . •AMG cycles per iteration descr ibes the a verage numb er of multigr id cycles ( V,W, flexible , and so on) p er it eration. •Relaxation sweeps per iteration descr ibes the numb er of r elaxa tion sw eeps (or it erative solu- tions) on all le vels f or all equa tions p er it eration. A relaxa tion sw eep is usually one it eration of G auss-S iedel or IL U. •Relaxation exchanges per iteration descr ibes the numb er of solution c ommunic ations b etween processors dur ing the r elaxa tion pr ocess in AMG. This numb er ma y be less than the numb er of sw eeps because of shif ting the linear sy stem on c oarser le vels t o a single no de/pr ocess. •Time-step updates per iteration descr ibes the numb er of sub-it erations on the time st ep p er iteration. •Time-step wall-clock time per iteration descr ibes the time p er sub-it eration. •Total wall-clock time descr ibes the t otal w all-clo ck time . The most r elevant quan tity is the Total wall clock time .This quan tity can b e used t o gauge the par allel p erformanc e (sp eedup and efficienc y) b y compar ing this quan tity to tha t from the ser ial analy sis. 43.9.2.1. Check ing L atenc y and B andwidth You c an check the la tency and band width of the o verall clust er in terconnec t, to help iden tify an y issues affecting ANSY S Fluen t scalabilit y, by click ing Latenc y and Band width in the Parallel ribbon tab (Network group b ox). Parallel → Network → Latenc y Depending on the numb er of machines and pr ocessors b eing used , a table c ontaining inf ormation about the c ommunic ation sp eed f or each no de will b e displa yed in the c onsole .The table will also summar ize the minimum and maximum la tency between t wo no des. Consider the f ollowing e xample when check ing f or la tency: Latency (usec) with 1000 samples [1.83128 sec] ------------------------------------------ ID n0 n1 n2 n3 n4 n5 ------------------------------------------ n0 48.0 48.2 48.2 48.3 *50 n1 48.0 48.2 48.3 48.3 *48 3099Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Check ing and Impr oving P arallel P erformanc e n2 48.2 48.2 48.8 49.1 *53 n3 48.2 48.3 *49 48.6 48.5 n4 48.3 48.3 49.1 48.6 *50 n5 49.7 48.5 *53 48.5 49.7 ------------------------------------------ Min: 47.9956 [n0<-->n1] Max: 52.6836 [n5<-->n2] ------------------------------------------ Imp ortant In the ab ove table , (*) is the maximum v alue in tha t row.The smaller the la tency, the b etter. Six pr ocessors (n0 t o n5) ar e spa wned .The la tency between n0 and n1 is 48.0 . Similar ly, the la tency between n1 and n2 is 48.2 .The minimum la tency occurs b etween n0 and n1 and the maximum latency occurs b etween n2 and n5, as not ed in the table . Check ing the la tency is par ticular ly useful when y ou ar e not seeing e xpected sp eedup on a clust er. Parallel → Network → Band width In addition t o check ing f or la tency, you c an check y our band width. A table c ontaining inf ormation about the amoun t of da ta communic ated within one sec ond b etween t wo no des is displa yed in the console .The table will also summar ize the minimum and maximum band width b etween t wo no des. Consider the f ollowing e xample when check ing f or band width: Bandwidth (MB/s) with 5 messages of size 4MB [4.36388 sec] -------------------------------------------- ID n0 n1 n2 n3 n4 n5 -------------------------------------------- n0 111.8 *55 111.8 97.5 101.3 n1 111.8 69.2 98.7 111.7 *51 n2 54.7 69.2 72.9 104.8 *45 n3 111.8 98.7 72.9 64.0 *45 n4 97.6 111.7 104.8 *64 76.9 n5 101.2 50.9 45.5 *45 76.9 -------------------------------------------- Min: 45.1039 [n5<-->n3] Max: 111.847 [n0<-->n3] -------------------------------------------- Imp ortant In the ab ove table , (*) is the minimum v alue in tha t row.The lar ger the band width, the better. The band width b etween n0 and n1 is 111.8 MB/s . Similar ly, the band width b etween n1 and n2 is 69.2 MB/s .The minimum amoun t of band width o ccurs b etween n3 and n5 and the maximum o ccurs between n0 and n3, as not ed in the table . Check ing the band width is par ticular ly useful when y ou cannot see go od sc alabilit y with r elatively lar ge c ases . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3100Parallel P rocessing43.9.3. Optimizing the P arallel S olver 43.9.3.1. Incr easing the R eport Int erval In ANSY S Fluen t, you c an r educ e communic ation and impr ove par allel p erformanc e by incr easing the report interval for residual pr inting/plotting or other solution monit oring r eports.You c an mo dify the value f or Rep orting In terval in the Run C alcula tion Task P age (p.3640 ). Solution → Run C alcula tion Calcula te... Imp ortant Note tha t you will b e unable t o in terrupt it erations un til the end of each r eport interval. 43.9.3.2. Acceler ating View Factor C alculations for G ener al P urp ose C omputing on Graphics P rocessing Units (GPGPUs) View fac tor c omputa tions c an b e acc elerated thr ough the viewfac_acc utilit y tha t uses a c ombin- ation of MPI/Op enMP/Op enCL mo dels t o sp eed up view fac tor c omputa tions . Irrespective of the numb er of MPI pr ocesses launched , only one MPI pr ocess/machine is used f or c omputing view fac tors. On each machine , one MPI pr ocess spa wns se veral Op enMP thr eads tha t actually c omput e the view factors. Since only one MPI pr ocess is r equir ed p er machine , it is r ecommended tha t you star t just one MPI pr ocess p er machine and sp ecify the numb er of Op enMP thr eads t o use when r unning the utilit y outside of ANSY S Fluen t.With f ewer MPI pr ocesses , the sy stem memor y usage is r educ ed as well.When r unning the utilit y from inside ANSY S Fluen t, the numb er of viewfac_acc processes will b e same as the numb er of ANSY S Fluen t processes . If Op enCL-c apable GPU s are available , then a portion of the view fac tor c omputa tions ar e done on GPU s using Op enCL, to fur ther sp eed up the computa tion. At presen t, this c apabilit y is limit ed t o the hemicub e metho d with the clust er-to-clust er option on lnamd64 and win64 machines . When using the utilit y viewfac_acc outside of ANSY S Fluen t, you c an sp ecify the f ollowing c ommand line options: •-cpu # (default = -2) The numb er of Op enMP thr eads t o launch p er machine . –-2:The numb er of MPI pr ocesses . –-1:The t otal numb er of lo gical CPU c ores. –0: No CPU used . –n: Up to maximum n. •-gpu # (default = 1) The numb er of GPU de vices to use p er machine . ––1:The t otal numb er of GPU de vices. –0: No GPU used . –n: Up to maximum n. 3101Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Check ing and Impr oving P arallel P erformanc e•-gpu_cpu_ratio # (default = 2.0) The r atio of the w ork load on 1 GPU v s 1 CPU Op enMP thr ead. This is based on the time c onsumed b y the GPU and the CPU. At the end of the view fac tor computa- tions , a recommenda tion is pr inted f or the GPU/CPU w ork load r atio t o use in futur e computa tions . When using the viewfac_acc utilit y from inside an ANSY S Fluen t session, use the /define/models/radiation/s2s-parameters/compute-clusters-and-vf-acceler- ated text interface (TUI) c ommand .You will only b e pr ompt ed f or the -gpu and -gpu_cpu_ratio options (as descr ibed pr eviously) and not the -cpu option, as the numb er of Op enMP thr eads t o launch p er machine c an b e sp ecified in the Thread C ontrol D ialog Box (p.3934 ) (see Controlling the Threads (p.3095 ) for details). In or der t o use the GPU f or view fac tor c omputa tions , the Op enCL libr ary should b e acc essible thr ough the appr opriate en vironmen t variable (LD_LIBRARY_PATH on lnamd64 or %path% on win64). By default on lnamd64, /usr/lib64 is sear ched , but if the libr ary is installed in another lo cation, then that location should b e sp ecified in the LD_LIBRARY_PATH variable . View fac tor c omputa tions c an also b e acc elerated thr ough the raytracing_acc utilit y tha t uses the NVIDIA Optix libr ary for tr acing the r ays.The GPU a vailable on the machine r unning the host process is used in such a sc enar io, except in a mix ed Windo ws-Linux simula tion wher e the GPU on node-0 is used . An NVIDIA GPU along with CUDA 6.0 is r equir ed f or using raytracing_acc . At presen t, this utilit y is a vailable only on lnamd64 (R ed Ha t En terprise Linux 5/6, and SUSE Linux En ter- prise S erver 11) and win64 ( Windo ws 7) machines f or 3D pr oblems . In or der t o use the utilit y, the CUDA 6.0 libr ary should b e acc essible thr ough the appr opriate en vironmen t variable (LD_LIB- RARY_PATH on lnamd64 or %path% on win64). When using the raytracing_acc utilit y from outside an ANSY S Fluen t session, the c ommand line is utility raytracing_acc [output_s2s_file(optional)] . When using the raytracing_acc utilit y from inside an ANSY S Fluen t session, use the /define/models/radiation/s2s-parameters/compute-clusters-and-vf-acceler- ated text user in terface (TUI) c ommand . 43.9.3.3. Acceler ating D iscr ete O rdinat es (DO) R adiation C alculations The acc elerated discr ete or dina tes (DO) r adia tion solv er is c omputa tionally fast er than the standar d DO solv er. Note tha t even though the acc elerated DO solv er ma y tak e mor e iterations t o converge, the o verall simula tion time is shor ter. After y ou ha ve selec ted the DO mo del in the Radia tion M odel dialo g box, you c an enable the acc el- erated DO solv er b y using the f ollowing t ext command: define → models → radiation → do-acceleration? If NVIDIA GPGPU s are enabled in the F luen t session, this solv er will acc elerate the DO c omputa tions by using the GPGPU s. In the absenc e of GPGPU s, this solv er can still b e used with the CPU c ores to accelerate the DO c omputa tions . Note tha t the acc elerated DO solv er uses the first-or der up wind scheme (and ignor es wha tever selec tion y ou ha ve made f or the Discr ete Or dina tes spa tial discr etiz- ation scheme in the Solution M etho ds task page), along with an e xplicit r elaxa tion of 1.0. The acc elerated DO solv er is inc ompa tible with some mo dels and settings; when nec essar y, Fluen t will aut oma tically r evert to the standar d DO solv er when the c alcula tion is star ted and pr int a message about the c onflic t. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3102Parallel P rocessingIf you plan t o use GPGPU s with the acc elerated DO solv er, it is r ecommended tha t you r un NVIDIA ’s multi-pr ocess ser ver (MPS) b efore launching ANSY S Fluen t using the f ollowing c ommand:nvidia- cuda-mps-control -d . It is k nown t o impr ove the r obustness and p erformanc e of the GPGPU computa tions with the multiple F luen t processes . 43.9.4. Clear ing the Linux F ile C ache Buff ers Processing p erformanc e can signific antly decr ease when the file c ache buff ers of a Linux machine ar e full. While this is tr ue in ser ial, it is mor e of ten a c oncern when solving lar ge c ases in par allel, par ticular ly when using AMD pr ocessors . If you see a p erformanc e decr ease e ven though the c ase / machine setup has not changed , tha t is an indic ation tha t the file c ache buff ers ma y be to blame . The filling of the file c ache buff ers c an happ en o ver a p eriod of time as a r esult of input-output ac tivit y. Even af ter the ANSY S Fluen t session is e xited, by default the op erating sy stem do es not fr ee up the file c ache buff ers immedia tely (unless the op erating sy stem is unable t o sa tisfy a mallo c subr outine request with a vailable fr ee memor y). During memor y allo cation f or a par allel c ase, this c an r esult in the allo cation of memor y from a diff erent NUMA domain, and c onsequen tly c an ha ve a signific ant impac t on p erformanc e. To resolv e this issue on Linux machines , you must first ensur e tha t all of the r elevant machines ar e idle (so tha t you do not ad versely aff ect an y jobs tha t are running). Then y ou c an clear the file c ache buff ers b y performing one of the f ollowing ac tions: •Include the -cflush option when launching ANSY S Fluen t from the c ommand line . This option ensur es tha t the file c ache buff ers ar e flushed in a separ ate op eration. While this pr ocess may tak e a f ew minut es to complet e (dep ending on the t otal memor y of the sy stem), it do es not requir e you t o ha ve root pr ivileges . or •Enter the (drop-cache) Scheme c ommand (either in the ANSY S Fluen t console or thr ough y our jour nal file) af ter launching F luen t but b efore you r ead the c ase file . This c ommand will instan taneously clear the pagec aches , den tries, and ino des. Imp ortant Note tha t in or der t o use the (drop-cache) command , you must ha ve sudo adminis- trative pr ivileges f or the /sbin/sysctl vm.drop_caches=3 command . 3103Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Check ing and Impr oving P arallel P erformanc eRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3104Chapt er 44: Design A naly sis and Optimiza tion In this chapt er, the setup and use of the adjoin t solv er and the mesh mor pher/optimiz er in ANSY S Fluen t are descr ibed. Both t ools off er shap e optimiza tion c apabilities , but the sc ope is c omplemen tary.The fundamen tal diff erence in the t echnolo gy is tha t the adjoin t solv er uses gr adien t-based optimiza tion by calcula ting der ivatives, wher eas the mesh mor pher/optimiz er uses a str ategy tha t is not based on gradien ts to decide design up dates. The t ools ha ve a c ommon appr oach t o change a design b y mor phing the c omputa tional mesh. This has the b enefit tha t you need not r etur n to the or iginal geometr y in or der t o up date the design f or the purposes of the optimiza tion. The t wo key consider ations when deciding whether t o use the adjoin t solv er or the mesh mor pher/op- timiz er ar e as f ollows: •Is the flo w ph ysics / obser vable of in terest supp orted b y the adjoin t solv er? (F or details ab out adjoin t cap- abilities , see the f ollowing sec tions: Basic A ssumptions and C onsist ency Checks (p.3121 ) and Gener al O bser v- ables (p.3107 )) If not , then the mesh mor pher/optimiz er is the b etter option, sinc e ther e are very few limita tions in the supp orted ph ysics and choic e of quan tity of in terest with this appr oach. It is imp ortant to verify tha t the quan tity of in terest c an b e sp ecified as an adjoin t solv er obser vable . •Is the dimension of the design spac e high? D etailed shap e optimiza tion of 3D geometr ies c an in volve design spac es with lar ge dimensions (thousands of degr ees of fr eedom or mor e).The adjoin t solv er is v ery eff ective in this sc enar io, wher eas the use of the mesh mor pher/optimiz er b ecomes c omputa tionally pr ohibitiv e when the numb er of degr ees of fr eedom e xceeds mor e than, say, 10–20. 44.1. The A djoin t Solver 44.2. Using the A djoin t Solver 44.3. The M esh M orpher/Optimiz er 44.4. Using the M esh M orpher/Optimiz er 44.1. The A djoin t Solver An adjoin t solv er is a sp ecializ ed t ool tha t extends the sc ope of the analy sis pr ovided b y a c onventional flow solv er b y pr oviding detailed sensitivit y da ta for the p erformanc e of a fluid sy stem. In or der t o perform a simula tion using the ANSY S Fluen t standar d flo w solv ers, a user supplies sy stem geometr y in the f orm of a c omputa tional mesh, specifies ma terial pr operties and ph ysics mo dels , and configur es b oundar y conditions of v arious t ypes.The c onventional flo w solv er, onc e converged , provides a detailed da ta set tha t descr ibes the flo w sta te go verned b y the flo w ph ysics tha t are being mo deled . Various p ostpr ocessing st eps c an b e tak en t o assess the p erformanc e of the sy stem. If a change is made t o an y of the da ta tha t defines the pr oblem, then the r esults of the c alcula tion c an change .The degr ee t o which the solution changes dep ends on ho w sensitiv e the flo w is t o the par tic- ular par amet er tha t is b eing adjust ed. Indeed , the der ivative of the solution da ta with r espect to tha t paramet er quan tifies this sensitivit y to first or der. Determining these der ivatives is the domain of sens- itivit y anal ysis. 3105Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.There is a lar ge c ollec tion of der ivative da ta tha t can b e comput ed f or a fluid sy stem, given the e xtensiv e set of input da ta tha t is r equir ed, and the e xtensiv e flo w da ta tha t is pr oduced.The ma trix of der ivatives of output da ta with r espect to input da ta can b e vast. Depending up on the goal of the analy sis only a portion of this der ivative da ta ma y be needed f or engineer ing analy sis and decision-mak ing. The adjoin t solv er acc omplishes the r emar kable f eat of c alcula ting the der ivative of a single engineer ing obser vation with r espect to a v ery lar ge numb er of input par amet ers simultaneously via a single c ompu- tation .The engineer ing obser vation c ould b e a measur e of the sy stem p erformanc e, such as the lif t or drag on an air foil, or the t otal pr essur e dr op thr ough a sy stem. Most imp ortantly, the der ivatives with respect to the geometr ic shap e of the sy stem ar e found . Understanding such sensitivities in a fluid sy stem c an pr ovide e xtremely v aluable engineer ing insigh t. A sy stem tha t is highly sensitiv e ma y exhibit str ong v ariabilit y in p erformanc e due t o small v ariations in manufac turing or v ariations in the en vironmen t in which it is op erating . Alternatively, high-sensitivit y may be leveraged f or fluid c ontrol, with a small ac tuator b eing able t o induc e str ong v ariations in b e- havior.Yet another p ersp ective is tha t sensitivit y of a p erformanc e measur e implies tha t the de vice in question is not fully optimiz ed and ther e is still r oom f or impr ovemen t—assuming tha t constr aints do not pr eclude fur ther gains . The sensitivities of a fluid sy stem pr ovided b y an adjoin t solv er sa tisfy a c entral need in gr adien t-based shap e optimiza tion. This mak es an adjoin t solv er a unique and p owerful engineer ing t ool for design optimiza tion. Adjoin t da ta can also pla y a r ole in impr oving solv er numer ics. Regions of high sensitivit y are indic ative of ar eas in the flo w wher e discr etiza tion er rors c an p otentially ha ve a str ong eff ect.This inf ormation can b e used t o guide ho w b est t o refine a mesh t o impr ove flo w solution accur acy. The pr ocess of c omputing an adjoin t solution r esembles tha t for a standar d flo w calcula tion in man y respects.The adjoin t solv er solution ad vancemen t metho d is sp ecified , residual monit ors c onfigur ed, and the solv er is initializ ed and r un thr ough a sequenc e of it erations t o convergenc e. One notable dif- ference is tha t a sc alar-v alued obser vation is selec ted as b eing of in terest pr ior t o star ting the adjoin t calcula tion. Onc e the adjoin t solution is c onverged the der ivative of the obser vable with r espect to the p osition of each and e very point on the sur face of the geometr y is a vailable , and the sensitivit y of the obser vation to sp ecific b oundar y condition settings c an b e found .This r emar kable f eature of adjoin t solutions has been k nown f or hundr eds of y ears , but only in the last f ew dec ades has the signific ance for c omputa- tional ph ysics analy sis b een r ecogniz ed widely . The p ower of this metho dolo gy is highligh ted when an alt ernative for assembling the same inf ormation is consider ed. Imagine a sequenc e of flo w calcula tions in which each p oint on an air foil sur face is mo ved in tur n a set small distanc e in the sur face-nor mal dir ection, and the flo w and dr ag r ecomput ed. If ther e are points on the sur face, then flow calcula tions ar e requir ed t o build the da ta set. Consider ing that the same da ta is pr ovided b y a single adjoin t computa tion, the adjoin t appr oach has an enor mous advantage . Rememb er tha t for e ven mo dest 3D flo w computa tions ther e ma y be man y thousands of coordina tes or mor e on a sur face. Onc e the adjoin t is c omput ed it c an b e used t o guide in telligen t design mo dific ations t o a sy stem. After all, the adjoin t sensitivit y da ta pr ovides a map acr oss the en tire sur face of the geometr y of the eff ect of mo ving the sur face. Design mo dific ations c an b e most eff ective if made in r egions of high sensitivit y sinc e small changes will ha ve a lar ge eff ect up on the engineer ing quan tity of in terest. This pr inciple of mak ing changes t o a sy stem in pr oportion t o the lo cal sensitivit y is the f ounda tion f or the simple gradien t algor ithm f or design optimiza tion. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3106Design A naly sis and Optimiza tionOnc e a c andida te change in shap e or other b oundar y condition has b een selec ted, the eff ect of tha t change c an b e estima ted using the c omput ed der ivative da ta.This amoun ts to a first or der e xtrapolation using a Taylor ser ies e xpansion ar ound the baseline flo w sta te. Clearly if a mo dific ation is chosen tha t is lar ge enough tha t nonlinear eff ects b ecome imp ortant then the accur acy of the pr edic ted change cannot b e guar anteed. 44.1.1. Gener al O bser vables Several obser vables ar e available and ser ve as the f ounda tion f or sp ecifying the quan tity tha t is of in- terest f or the c omputa tion. Basic quan tities such as f orces and momen ts can b e defined and each is given a name .The f ollowing t ypes of obser vables ar e available: •Force: the aer odynamic f orce in a sp ecified dir ection on one or mor e walls. •Momen t of f orce: the aer odynamic momen t ab out a sp ecified momen t center and momen t axis .The in teg- ration is made o ver a sp ecified c ollec tion of w all z ones . Note tha t in 2D , the momen t axis is nor mal t o the plane of the flo w. •Swirl: the momen t of the mass flo w (with v elocity ) relative to an axis defined b y a p oint, , and a dir ection .The t wo options ar e: –Swirl integral (44.1) wher e denot es the v olume o ver which the in tegration is made , and denot es the r elative position t o the p oint . –Normaliz ed swir l integral (44.2) Note These in tegrals c an b e used t o constr uct quan tities such as tumble r atio tha t are of signi- ficance for in ternal c ombustion engine analy sis. •pressur e dr op b etween an inlet (or gr oup of inlets) and an outlet (or gr oup of outlets) The t otal pr essur e is c omput ed b y area-w eigh ted a veraging of the t otal pr essur e values on selec ted surfaces. •fixed v alue: a simple fix ed v alue c an b e sp ecified and used in the assembly of the obser vables .This is c on- venien t when some sc aling or nor maliza tion of the obser vable is desir ed. It must b e not ed tha t this v alue is treated str ictly as a c onstan t for the pur poses of an y der ivative calcula tions . •surface in tegral: a variety of sur face in tegrals c an b e constr ucted f or a sp ecified field v ariable on a set of user-selec ted sur faces (including z one sur faces, isosur faces, and clipp ed sur faces). 3107Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.The A djoin t Solver–Facet sum: a simple sum of the field v alue on each fac et of the c omputa tional mesh. (44.3) –Facet average: the fac et sum is divided b y the t otal numb er of fac ets, . (44.4) –Facet varianc e: the sum of the squar es of the de viations fr om the fac et average divided b y the t otal numb er of fac ets. (44.5) –Integral: the sum of the field v alue on each fac e multiplied b y the fac e area. (44.6) –Area-w eigh ted a verage: the in tegral divided b y the t otal fac e area. (44.7) –Area-w eigh ted v arianc e: the sum of the squar es of the de viations fr om the ar ea-w eigh ted a verage, divided by the t otal fac e area. (44.8) –Mass-w eigh ted in tegral: the sum of the field v alue on each fac e, weigh ted b y the magnitude of the lo cal mass flo w thr ough the fac e. (44.9) –Mass-w eigh ted a verage in tegral: the mass-w eigh ted in tegral divided b y the sum of the magnitudes of the lo cal mass flo w rates thr ough the fac es on which the in tegral is defined . (44.10) –Mass-w eigh ted v arianc e: the mass-w eigh ted in tegral of the squar e of the de viation fr om the mass- weigh ted a verage, divided b y the sum of the magnitudes of the lo cal mass flo w rates thr ough the fac es on which the in tegral is defined . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3108Design A naly sis and Optimiza tion(44.11) –Flow-rate weigh ted: the r ate at which the field is c onvected thr ough the defined sur faces. (44.12) –The field v ariables tha t can b e used ar e: →Pressur e →Total pr essur e →Mass flo w per unit ar ea →Temp erature (when adjoin t ener gy is enabled) →Total t emp erature (when adjoin t ener gy is enabled) →Heat flux (when adjoin t ener gy is enabled) •volume in tegral: you c an c omput e a v ariety of v olume in tegrals of a chosen field v ariable . –Volume: comput es the t otal v olume of the selec ted z ones as a summa tion of the individual c ell v olumes . (44.13) –Sum: comput es the sum of a chosen field v ariable o ver the selec ted z ones . (44.14) –Volume In tegral: is calcula ted b y summing the pr oduc t of c ell v olume and the selec ted field v ariable over the selec ted z ones . (44.15) –Volume-W eigh ted A verage: is comput ed b y dividing the v olume in tegral of a selec ted field v ariable (Equa tion 44.15 (p.3109 )) by the t otal v olume of the selec ted z ones . (44.16) –Volume Varianc e: is the v olume-w eigh ted in tegral of the squar e of the de viation fr om the v olume- weigh ted a verage ( Equa tion 44.16 (p.3109 )), divided b y the t otal v olume of the selec ted z one . 3109Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.The A djoin t Solver(44.17) –Mass In tegral: is comput ed b y summing the pr oduc t of densit y, cell v olume , and the chosen field v ariable . (44.18) –Mass: is comput ed b y summing the pr oduc t of c ell densit y and c ell v olume . (44.19) –Mass-W eigh ted A verage: is comput ed b y dividing the M ass In tegral of the chosen field v ariable ( Equa- tion 44.18 (p.3110 )) by the t otal M ass ( Equa tion 44.19 (p.3110 )). (44.20) –Mass Varianc e: is comput ed as the mass-w eigh ted summa tion of the squar e of the de viation of the chosen field v ariable fr om its mass-w eigh ted a verage ( Equa tion 44.20 (p.3110 )) divided b y the t otal mass (Equa tion 44.19 (p.3110 )). (44.21) The v olume in tegrals list ed ab ove can b e comput ed f or the f ollowing field v ariables: –Pressur e –Total P ressur e –Temp erature (when adjoin t ener gy is enabled) –Total t emp erature (when adjoin t ener gy is enabled) –Velocity –Velocity Magnitude –Vorticit y –Vorticit y Magnitude –Turbulenc e Produc tion: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3110Design A naly sis and Optimiza tion44.1.2. Gener al Op erations Several op erations ar e available t o combine obser vables in v arious w ays, if needed , to mak e a wide variety of c omp ound obser vables .The f ollowing op erations ar e available: •ratio of t wo quan tities •produc t of t wo quan tities •linear c ombina tion of quan tities , with c onstan t coefficien ts raised t o various powers , plus a c onstan t off set . (44.22) •arithmetic a verage of quan tities (44.23) •mean v arianc e of quan tities (44.24) •unar y op eration (sin, cosine , and so on) on obser vable v alue : – – – – – – – – – –ln –log10 3111Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.The A djoin t Solver44.1.3. Discr ete Versus C ontinuous A djoin t Solver When an adjoin t solv er is de velop ed ther e is a k ey design decision tha t is made r egar ding the imple- men tation, namely whether t o use a continuous or a discr ete appr oach. Both appr oaches ar e in tended to comput e the same sensitivit y da ta—ho wever, the appr oaches ar e remar kably diff erent. While a user of the adjoin t solv er ma y experienc e no par ticular diff erence in w orkflow for the t wo separ ate solv er types, it is imp ortant to be aware tha t ther e ar e two pr imar y classes of adjoin t solv er and the appr oach chosen c an ha ve implic ations f or the accur acy of the r esults . A continuous adjoint sol ver relies hea vily on ma thema tical pr operties of the par tial-diff erential equa tions that define the ph ysics of the pr oblem. In this c ase those equa tions ar e the N avier-S tokes equa tions . With this appr oach an adjoin t par tial diff erential equa tion set is f ormula ted e xplicitly and is acc ompanied by adjoin t boundar y conditions tha t are also der ived ma thema tically. Only af ter this der ivation is complet e can the adjoin t par tial diff erential equa tions b e discr etized and solv ed, often with e xtensiv e re-use of e xisting solv er machiner y.This class of solv er w as implemen ted b y ANSY S Fluen t as a r esear ch effort. Such a solv er has the b enefit tha t it is dec oupled lar gely fr om the or iginal flo w solv er.They shar e only the fac t tha t the y are based on the N avier-S tokes equa tions .The pr ocess of discr etizing and solving the par tial diff erential equa tions in each c ase c ould in pr inciple b e very diff erent indeed .While this flexibilit y ma y be app ealing it c an also b e the do wnfall of the appr oach. Inconsist encies in mo deling , discr etiza tion and solution appr oaches c an p ollut e the sensitivit y inf ormation signific antly, esp ecially for pr oblems with w all func tions and c omple x engineer ing c onfigur ations such as those of in terest t o ANSY S Fluen t users . The c ontinuous adjoin t appr oach c an b e eff ective for some classes of pr oblems . However, until ther e is a signific ant ad vance in handling some k ey challenges , ANSY S Inc . has c oncluded tha t it is an unsuit- able appr oach f or meeting the needs of our br oad clien t base f or the classes of pr oblems of in terest to them. A discr ete adjoint sol ver is based not on the f orm of the par tial diff erential equa tions go verning the flow, but the par ticular discr etized f orm of the equa tions used in the flo w solv er itself .The sensitivit y of the discr etized equa tions f orms the basis f or the sensitivit y calcula tion. In this appr oach the adjoin t solv er is much mor e tigh tly tied t o the sp ecific implemen tation of the or iginal flo w solv er.This has been obser ved t o yield sensitivit y da ta tha t provides v aluable engineer ing guidanc e for the classes of problem of in terest t o ANSY S Fluen t users , including pr oblems with w all func tions . For the ab ove reasons , the discr ete adjoin t appr oach has b een adopt ed f or the ANSY S Fluen t adjoin t solv er. 44.1.4. Discr ete Adjoin t Solver O verview As discussed in the pr evious sec tion, a discr ete adjoin t appr oach t o solving the adjoin t problem has been adopt ed, sinc e it is b elieved t o pr ovide the most useful engineer ing sensitivit y da ta for the classes of pr oblems of in terest t o ANSY S clien ts. An adjoin t metho d can b e used t o comput e the der ivative of an obser vation of in terest f or the fluid system with r espect to all the user-sp ecified par amet ers,with any changes that ar ise in the flo w v ariables themsel ves eliminat ed.There ar e thr ee k ey ingr edien ts to consider when de veloping the metho d: 1.All of the user-sp ecified inputs: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3112Design A naly sis and Optimiza tion•All values set b y a user in the b oundar y condition panels f or each b oundar y in the pr oblem. •The c omputa tional mesh. More sp ecific ally the lo cations of the no des of the mesh and ho w the y define the edges , faces, and ultima tely the c ells used in the finit e-volume c omputa tion. This includes b oth interior as w ell as b oundar y no des. •Material pr operties. •Model par amet ers such as mo del c oefficien ts for turbulenc e mo dels . Note tha t the settings tha t define the pr oblem ar e being distinguished fr om settings tha t define how the solution ad vancemen t is t o be performed t o converge the pr oblem. Only the f ormer ar e of in terest her e. For the sak e of clar ity, let us denot e the v ector of all of the v alues in the list b y . These ar e consider ed t o be the c ontrol variables f or the pr oblem, tha t is, the v ariables tha t a user can set e xplicitly tha t aff ect the solution. It is w orth noting tha t the t opological definition of the mesh is fix ed—it is not c onsider ed t o be a control variable her e.The eff ect of c ollapsing c ells or r emeshing on the flo w solution is not addr ess- able without fur ther de velopmen t in view of the discr ete changes tha t are implied .This t opic is beyond the sc ope of the cur rent do cumen t. 2.The go verning equa tions f or the fluid sy stem: The main eff ort in a flo w computa tion is in the det ermina tion of the flo w sta te, namely the v elocity, pressur e, densit y and p ossibly other fluid-r elated v ariables . For a c ell-c entered finit e-volume scheme , the flo w sta te is defined a t the c ell c entroids b y a v ector of r eal v alues . In the simplest c ase these values ar e the pr essur e and flo w velocity comp onen ts. Let the v ector of the v ariables in the th cell b e denot ed her e by . At convergenc e the flo w variables sa tisfy (44.25) wher e is the numb er of c ells in the pr oblem, and ther e ar e conditions on each c ell.This e x- pression is a c ompac t way of denoting c onser vation of mass and momen tum and other c onstr aints. 3.The engineer ing obser vation of in terest: Let (44.26) denot e a sc alar of in terest tha t dep ends b oth on the flo w sta te and p erhaps dir ectly on the c ontrol variables . It is assumed tha t the obser vable is diff erentiable with r espect to both the flo w and the controls.The inclusion of the c ontrol variables her e is essen tial sinc e in man y cases the mesh geometr y is included dir ectly in the e valua tion of the obser vable . For e xample , the e valua tion of the f orce on a b oundar y involves the w all nor mal and fac e ar eas, which change when mesh no des are mo ved. The goal is t o det ermine the sensitivit y of the obser vation with r espect to the user-sp ecified c ontrol variables .What mak es defining this r elationship mor e challenging is the fac t tha t changing the user inputs changes the flo w, which indir ectly changes the engineer ing obser vation. The adjoin t metho d has a sp ecific r ole in managing this chain of influenc es b y pr oviding a mechanism f or elimina ting the specific changes tha t happ en in the flo w whene ver the inputs change . 3113Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.The A djoin t SolverIf a v ariation is in troduced in to the c ontrol variables then a linear ization of the go verning equa tions (Equa tion 44.25 (p.3113 )) sho ws tha t the v ariations in the flo w sta te must sa tisfy (44.27) wher e ther e is an implied summa tion o ver and , and denot es tha t the flo w solution is held c onstan t while the der ivative is tak en. Meanwhile , if b oth the c ontrol variables and the flo w sta te change , then the obser vation will change: (44.28) The par ticular w ay in which the flo w responds t o the changes in the c ontrol variables c an b e comput ed using ( Equa tion 44.27 (p.3114 )) only af ter sp ecific changes , , have been chosen. It is pr ohibitiv e to consider solving ( Equa tion 44.27 (p.3114 )) for mor e than a handful of pr escr ibed changes because of the e xcessiv e computing time tha t would b e needed . However, when r edesigning the shap e of parts of a sy stem ther e ma y be pr essur e to explor e a lar ge numb er of c andida te mo dific ations .This conflic t is r econciled b y elimina ting the v ariations of the flo w solution fr om the e xpression ( Equa- tion 44.28 (p.3114 )) and pr oducing an e xplicit r elationship b etween changes in the c ontrol variables and the obser vation of in terest. This is acc omplished b y tak ing a w eigh ted linear c ombina tion of the linear ized go verning equa tions (Equa tion 44.27 (p.3114 )) in a v ery par ticular w ay. A set of adjoin t variables is in troduced with a one- to-one c orrespondenc e with the go verning equa tions ( Equa tion 44.25 (p.3113 )).This r esults in a r elation- ship (44.29) The t erm in squar e br ackets on the lef t is no w ma tched t o the c oefficien t for the v ariation in the flo w in (Equa tion 44.28 (p.3114 )) in or der t o define v alues f or the adjoin t variables: (44.30) These ar e the discr ete adjoin t equa tions , and the solution of this sy stem tha t is the pr imar y goal f or the adjoin t solv er. It is imp ortant to recogniz e tha t these equa tions ha ve not b een der ived.They are defined in this w ay with a sp ecific goal in mind—the elimina tion fr om ( Equa tion 44.28 (p.3114 )) of the perturba tions t o the flo w field as sho wn b elow: (44.31) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3114Design A naly sis and Optimiza tionNote the use of Equa tion 44.29 (p.3114 ) and Equa tion 44.30 (p.3114 ) in the der ivation of Equa- tion 44.31 (p.3114 ).The flo w p erturba tion has no w b een elimina ted fr om the e xpression, yielding a direct relation b etween the c ontrol variables and the obser vable of in terest. There ar e se veral imp ortant obser vations t o be made ab out ( Equa tion 44.30 (p.3114 )): •The dimension of the pr oblem t o be solv ed is the same as the or iginal flo w pr oblem, although the adjoin t problem is linear . •While the adjoin t solution ma y be consider ed str ictly as a v ector of numer ic values , experienc e with the continuous adjoin t provides guidanc e on ho w the adjoin t solution c an b e interpreted.The v ector of w eigh ts asso ciated with the c omp onen ts of the r esidual of the momen tum equa tion in each c ell is t ermed the adjoint velocity.The adjoin t value asso ciated with the r esidual of the c ontinuit y equa tion is t ermed the adjoint pressur e. •The r ight hand side is defined pur ely on the basis of the obser vable tha t is of in terest. •The ma trix on the lef t hand side is the transp ose of the Jac obian of the go verning sy stem of equa tions (Equa tion 44.25 (p.3113 )).This seemingly inno cent transp osition has a v ery dr ama tic impac t on ho w the adjoin t system is solv ed.This will b e discussed b elow. •The adjoin t equa tions ar e defined b y the cur rent sta te of the flo w, and the sp ecific ph ysics tha t is emplo yed in the mo deling . Each adjoin t solution is sp ecific t o the flo w sta te. At first glanc e it app ears tha t solving the adjoin t problem ma y be str aigh tforward. After all it simply involves setting-up and solving a linear (alb eit lar ge) sy stem of equa tions . In pr actice both st eps c an represen t a signific ant challenge , esp ecially when the pr oblem is lar ge. The e valua tion of the r esiduals of the flo w equa tions is an in tegral par t of the pr e-existing ANSY S Fluen t flo w solv ers. However, it is nec essar y to comput e the Jac obian of the sy stem and then tr ansp ose it , or a t the v ery least t o be able t o mak e a ma trix-fr ee tr ansp ose ma trix-vector pr oduc t with the adjoin t solution. There ar e se veral technic al appr oaches t o acc omplishing this task whose descr iption go es b eyond the sc ope of this do cumen t. Suffic e to sa y tha t it is not tr ivial t o enc ode this func tionalit y, but tha t it has b een done succ essfully her e. For the pr esen t implemen tation, a pr e-conditioned it erative scheme , based on pseudo-time mar ching , is adopt ed t o solv e the adjoin t system. The equa tions tha t define the ad vancemen t process c an b e written as (44.32) wher e is a lo cal time st ep siz e based on the lo cal flo w conditions , is a user-sp ecified CFL numb er.The ma trix is a simplified f orm of the sy stem Jac obian tha t is amenable t o solution using the AMG linear solv er tha t is the w orkhorse of the c onventional flo w solv er.The pr econditioning matrix is a diagonal ma trix. Artificial c ompr essibilit y is in troduced on the adjoin t continuit y equa tion to aid in the r elaxa tion of the adjoin t pressur e field . The c orrection is under-r elax ed and added t o the adjoin t solution and the pr ocess r epeated until the r ight hand side is adequa tely small. 3115Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.The A djoin t Solver44.1.5. Adjoin t Solver S tabiliza tion When applied t o pr oblems with lar ge c ell c oun ts and c omple x geometr y, adjoin t solv ers sometimes experienc e stabilit y issues .These instabilities c an b e asso ciated with small sc ale unst eadiness in the flow field and/or str ong shear , and t end t o be restricted t o small and isola ted r egions of the flo w domain. Despit e the spa tial lo caliza tion of these instabilities , the linear ity of the adjoin t problem pr ovides no intrinsic limit on their gr owth dur ing solution ad vancemen t.Their pr esenc e, if not handled , can disr upt the en tire adjoin t calcula tion despit e the pr oblem o ccur ring in sometimes just a f ew c ells. A stabiliz ed solution scheme will b e requir ed t o obtain adjoin t solutions f or pr oblems a t high R eynolds numb er in which ther e is str ong shear and/or c omple x geometr y. Four stabiliza tion schemes ar e available in F luen t in or der t o overcome these stabilit y difficulties when larger c ases ar e being solv ed.You c an cho ose t o apply one of them a t all times , or use a blended strategy wher e up t o two diff erent schemes ar e used a t diff erent points in the solution. The stabiliza tion schemes ar e designed t o in tervene only when the standar d ad vancemen t scheme is e xperiencing in- stabilit y. Dissipa tion scheme The dissipa tion scheme pr ovides stabiliza tion f or the solution ad vancemen t of the adjoin t solution b y introducing nonlinear damping str ategic ally in to the c alcula tion domain. The str ategy is in tended t o provide minimal in tervention in or der t o damp the gr owth of instabilities tha t lead t o adjoin t solution divergenc e. A mar ker is tr acked, based on the sta te of the adjoin t solution, and damping is applied dir ectly to the adjoin t solution in r egions wher e the mar ker b ecomes lar ge. Unlike the mo dal, spa tial, and r esidual minimiza tion schemes , the dissipa tion scheme c an aff ect the adjoin t solution sligh tly. In gener al, the spa tial or der of the damping is chosen t o be one or der larger than the adjoin t calcula tion or der.This means tha t the f ormal or der of accur acy of the adjoin t solv er is unaff ected b y the addition of the dissipa tion scheme . In pr actice, regions of in tense dis- sipa tion c an app ear f or some c ases which ma y result in isola ted sp ots and/or str eaks in the solution on sur faces. However, the sc ale of these solution f eatures is such tha t the y are of ten easily smo othed during p ostpr ocessing t o gener ate design changes . Residual minimiza tion scheme The r esidual minimiza tion scheme uses a GMRES-lik e scheme t o appr oxima te the solution b y the vectors in a K rylov subspac e with minimal r esidual. The o verall adjoin t residual is guar anteed t o decr ease .This is a unique b enefit c ompar ed t o the other a vailable schemes . Note tha t this scheme is expensiv e with r egar d to memor y.When it is enabled , each main it eration c onsists of multiple sub-it erations , wher e one sub-it eration is equiv alen t to one nor mal adjoin t iteration. Spatial scheme The spa tial scheme op erates b y iden tifying par ts of the domain wher e unstable gr owth is o ccur ring and applying a mor e dir ect and stable solution pr ocedur e in those r egions . Modal scheme The mo dal scheme in volves a pr ocess of iden tifying the par ticular details of the unstable gr owth pa tterns or mo des.These pa tterns ar e localized in spac e and the y are used t o split the solution in to par ts tha t ha ve stable and unstable char acteristics when ad vanced.The stable par t is ad vanced as usual, while the algor ithm is designed no w to comp ensa te for the unstable par t so tha t the o verall c alcula tion is stabiliz ed. The emer genc e of the unstable pa tterns c an happ en a t an y time dur ing the adjoin t calcula tion and the t otal numb er of unstable pa tterns is c ase-dep enden t. Having 10 t o 20 unstable mo des presen t would not b e consider ed unusual. Large c ases ma y ha ve man y mor e. As a gener al tr end , Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3116Design A naly sis and Optimiza tionthe most r apidly-gr owing unstable pa tterns app ear of ten within a f ew it erations with mor e slo wly- growing mo des app earing la ter in the c alcula tion. The unstable pa tterns ar e handled as the y app ear. Some additional c omputa tional o verhead is asso ciated with the stabiliza tion schemes . In gener al, the dissipa tion scheme is the least r esour ce-in tensiv e of the f our schemes . For inf ormation ab out using the stabiliza tion schemes , refer to Stabiliza tion S trategies , Schemes , and Settings (p.3134 ). 44.1.6. Solution-B ased A daption An adjoin t solution pr ovides guidanc e on wher e best t o adapt a c omputa tional mesh in or der t o resolv e quan tities of engineer ing in terest. Onc e the go verning equa tions f or the sy stem ( Equa tion 44.25 (p.3113 )) ha ve been c onverged ther e re- mains a discr etiza tion er ror, , such tha t (44.33) While sp ecific estima tes for this discr etiza tion er ror ma y be tricky to define , it is of ten estima ted t o be , wher e is the lo cal gr id siz e, and is the or der of the discr etiza tion scheme .That is, for a first-or der scheme and for a sec ond or der scheme . Alternatively, can b e consider ed t o be the residual asso ciated with a solution tha t is not c onverged fully . The c orrection t o the flo w field , , tha t comp ensa tes for this inhomo geneit y is giv en b y (44.34) from which it f ollows quick ly tha t (44.35) This simple e xpression pr ovides an estima te of the eff ect of the pr esenc e of on the obser vation, . The pr esenc e of discr etiza tion er rors, or lack of c onvergenc e, on the engineer ing quan tity of in terest is assessed b y weigh ting the inhomo geneous t erm b y the lo cal adjoin t solution. It is clear tha t even in regions of the domain wher e the r esiduals or discr etiza tion er rors ar e small, an acc ompan ying adjoin t velocity or pr essur e tha t is lar ge in magnitude implies tha t ther e ma y be a signific ant sour ce of er ror in the obser vable . A finer mesh in r egions wher e the adjoin t is lar ge will r educ e the influenc e of dis- cretiza tion er rors tha t ma y ad versely aff ect the engineer ing r esult of in terest. In pr actice, adapting c ells which ha ve lar ge magnitude adjoin t velocity and/or adjoin t pressur e will achie ve this goal. 44.1.7. Using The D ata To Impr ove A D esign Adjoin t sensitivit y da ta can b e used t o guide ho w to mo dify a sy stem in or der t o impr ove the p erform- ance.The obser vable of in terest c an b e made lar ger or smaller , dep ending up on the engineer ing goal. A common str ategy for deciding ho w to mo dify the sy stem is based on the gr adien t algor ithm. The under lying pr inciple is quit e simply tha t mo difying a sy stem in a manner t o which it is most sensitiv e maximiz es the eff ect of the change .The change t o a c ontrol variable is made in pr oportion t o the sensitivit y of the v alue of in terest with r espect to tha t control variable . 3117Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.The A djoin t SolverDenot e the sensitivit y of the c ost with r espect to shap e by (44.36) wher e is the th coordina te of the th node in the mesh. Here is a nota tion f or the subset of the c ontrol variables for the sy stem tha t correspond t o mesh no de p ositions .Then an adjustmen t (44.37) will pr ovide the maximum adjustmen t to for giv en nor m of , wher e is an arbitr ary sc aling factor. Note tha t can b e pick ed t o be positiv e or nega tive dep ending up on whether is to be in- creased or decr eased r espectively.This is essen tially a sta temen t of the metho d of st eepest desc ent. Further mor e, the change is estima ted t o first or der t o be (44.38) For a sufficien tly small adjustmen t, the change t o the obser vation will str ictly ha ve the same sign as the sc aling fac tor , provided the gr adien t is not iden tically z ero. In regions wher e the sensitivit y is high, small adjustmen ts to the shap e will ha ve a lar ge eff ect on the obser vable .This c orresponds dir ectly with the idea of engineer ing r obustness . If a c onfigur ation sho ws high sensitivities , then the p erformanc e will lik ely b e subjec t to lar ge p erformanc e variations if ther e are manufac turing inc onsist encies . For a r obust design, the goal is t o ha ve the sensitivit y be toler ably small. In pr actical cases the field can b e noisy , esp ecially f or lar ge, turbulen t flo w pr oblems . If the noisy field is used dir ectly t o mo dify a b oundar y shap e using ( Equa tion 44.37 (p.3118 )), then the mo dified surface can ha ve man y inflec tions .This is not helpful f or engineer ing design w ork. In the ne xt sec tion, the use of mesh mor phing t echnolo gy not only t o smo oth the sensitivit y field , but also t o pr ovide smo oth b oundar y and in terior mesh def ormation, is descr ibed. 44.1.7.1. Smo othing and Mesh Morphing As has b een not ed, for typic al engineer ing pr oblems , the shap e sensitivit y field c an ha ve smo othness properties tha t are not adequa te to define a shap e mo dific ation. Mesh mor phing t echnolo gy is used here for b oth t wo- and thr ee-dimensional sy stems in a t wo-fold r ole.The first r ole is as a smo other for the sur face sensitivit y field .The sec ond r ole is t o pr ovide smo oth dist ortions not only of the boundar y mesh, but also the in terior mesh. This appr oach is v ery app ealing sinc e it func tions f or ar- bitrary mesh c ell t ypes. A Cartesian or c ylindr ical region is defined such tha t it enc ompasses all or a par t of the pr oblem domain. Only the mesh no des tha t fall within this r egion ma y mo ve as a r esult of the mor phing op eration. In gener al, an optimiza tion pr oblem ma y include b oth fr ee-f orm minimiza tion or maximiza tion of the obser vable(s) and c onstr aints tha t are lo calized in spac e.This r equir es appr oaches tha t can pr ovide a def ormation field tha t is w ell-b ehaved and c onsist ent with manufac turabilit y requir emen ts, while still allo wing lo cally shar per def ormations wher e requir ed t o sa tisfy the imp osed c onstr aints. For the adjoin t solv er, Fluen t provides t wo diff erent mor phing t echniques: one based on p olynomials , and another tha t uses dir ect interpolation. Note tha t these metho ds ar e based on diff erent design spac es, and so will pr oduce diff erent mor phing r esults . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3118Design A naly sis and Optimiza tion44.1.7.1.1. Polynomials-B ased A ppr oach Note For simplicit y, the smo othing and mor phing equa tions pr esen ted her e ar e for the c ase of a 2D domain. The same appr oach is e xtended and used f or 3D pr oblems . For the p olynomials-based mor phing appr oach, a lo cal ( , ) coordina te sy stem is defined , wher e and . A regular ar ray of control p oints is then distr ibut ed in the c ontrol volume .The motion of the mesh a t an y point in the domain is det ermined b y the mo vemen t of the control p oints. Bernstein p olynomials and B-splines ar e used t o map the c ontrol p oint motions t o the c omputa tional mesh no des. The th Bernstein p olynomial of degr ee is: (44.39) The th B-spline of degr ee is the non-p eriodic B-spline tha t uses a k not-v ector, , wher e: (44.40) The v alue of the B-spline is defined r ecursiv ely as: (44.41) Depending on the degr ee of the B-spline , the func tion is z ero on some p ortion of the unit in terval. This is in c ontrast t o the B ernstein p olynomials tha t are str ictly non-z ero everywher e on the unit in- terval. Let denot e the th coordina te of the th mesh no de, and let denot e the change in the p os- ition of the no de due t o the mor phing pr ocess. Let denot e the displac emen t of the th control p oint asso ciated with the B ernstein p olynomials in the th coordina te dir ection, and let denot e the displac emen t of the th control p oint asso ciated with the B-splines . If denot es the p osition of the th mesh no de, then the displac emen t of the no de is defined b y the sup erposition: (44.42) The c ontrol-p oint mo vemen t for the B ernstein p olynomials c ontrols the lar ge-sc ale smo oth def orm- ation, while the c ontrol-p oint mo vemen t for the B-splines c ontrols fine-sc ale motions . 44.1.7.1.2. Direct Int erp olation Metho d In the dir ect interpolation metho d, the def ormation of the in terior mesh c an b e view ed as a pr ojec tion of the def ormation fr om the b oundar y into the in terior.The displac emen t of the in terior mesh is calcula ted as a w eigh ted a verage of all b oundar y no de displac emen t: 3119Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.The A djoin t Solver(44.43) wher e and are the in terior and b oundar y no de displac emen ts respectively, is the weigh ting func tion, and is the distanc e between the ith and jth nodes. When deciding which mor phing metho d to cho ose, consider the f ollowing ad vantages of the dir ect interpolation metho d compar ed t o the p olynomials-based appr oach: •It can handle design c onditions b etter than the p olynomials-based appr oach. •The design t ool converges fast er with the dir ect interpolation metho d: it converges with one it eration for most design c onditions . •Setting up the dir ect interpolation metho d is much simpler , as the f ollowing c ontrols do not need t o be defined: most of the numer ics settings , the fr eeform sc aling scheme , the fr eeform sc ale fac tor, and the numb er of c ontrol p oints. •The design c onditions ar e sa tisfied e xactly, even without applying str ict conditions . While the dir ect interpolation metho d has signific ant ad vantages , it also has the f ollowing limita tions: •The in terior mesh qualit y ma y not b e as go od as tha t produced b y the p olynomials-based appr oach (though y ou ma y be able t o mitiga te this b y using the Impr ove M esh dialo g box). Boundar y zones ar e also mor e at risk: the y ma y cross / p enetr ate themselv es or other b oundar y zones , which ma y or ma y not gener ate a w arning ab out c ells with nega tive volumes; as a r esult , you must visually r eview the mesh node changes , and r educ e the tar get changes as needed . •Non-c onformal in terfaces should not under go fr ee def ormation, as the mor phing ma y mo ve the t wo sides apar t. •Some r egion c onditions ar e not supp orted, such as in varianc e, symmetr y of motion, and r egion b oundar y continuit y. 44.2. Using the A djoin t Solver This sec tion descr ibes the pr ocess f or loading the adjoin t solv er mo dule , as w ell as setting up , running , and p ostpr ocessing the adjoin t solutions .This sec tion also demonstr ates ho w the adjoin t solution c an guide the mo dific ation of the b oundar y shap es. The t ypic al use of the adjoin t solv er in volves the f ollowing st eps (though not all of these ma y be nec es- sary for e very workflow): 1.Load or c omput e a c onventional flo w solution. 2.Specify the obser vable(s) of in terest. 3.Set the adjoin t solv er controls. 4.Set the adjoin t solv er monit ors and c onvergenc e criteria. 5.Initializ e the adjoin t solution and it erate to convergenc e. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3120Design A naly sis and Optimiza tion6.Postpr ocess the adjoin t solution t o extract the sensitivit y of the obser vable with r espect to the b oundar y condition settings and the shap e of the geometr y. 7.Set up the Design Tool and c alcula te the optimal design change . 8.Modify the b oundar y shap es based on shap e-sensitivit y da ta and r ecomput e the flo w solution. The former c an b e done thr ough the Design Tool, wher eas multiple it erations of b oth the f ormer and the la tter can b e performed b y the Gradien t-Based Optimiz er. This sec tion pr ovides inf ormation ab out using the ANSY S Fluen t adjoin t solv er in the f ollowing sec tions: 44.2.1. Model C onsider ations f or U sing A djoin t Solver 44.2.2. Defining O bser vables 44.2.3. Solving the A djoin t 44.2.4. Postpr ocessing of A djoin t Solutions 44.2.5. Modifying the G eometr y Using the D esign Tool 44.2.6. Using the G radien t-Based Optimiz er In addition, see the F luen t Tutorials f or mor e inf ormation ab out using the adjoin t solv er. (To acc ess tu- torials and their input files , go t o the tutorials ar ea of the cust omer sit e.) 44.2.1. Model C onsider ations f or U sing A djoin t Solver The cur rent adjoin t solv er implemen tation pr ovides basic adjoin t solutions tha t acc ompan y a c onven- tionally-c omput ed flo w solution pr ovided c ertain cr iteria ar e met. 44.2.1.1. Basic A ssumptions and C onsist ency Checks 44.2.1.2. User-D efined S ources 44.2.1.1. Basic Assumptions and C onsist enc y Checks The adjoin t solv er is implemen ted on the f ollowing basis: •The flo w sta te is f or a st eady single-phase flo w, or ideal gas , tha t is either laminar or turbulen t. •For turbulen t flo ws, a frozen turbulenc e assumption is made , in which the eff ect of changes t o the sta te of the turbulenc e is not tak en in to acc oun t when c omputing sensitivities . •For turbulen t flo ws, the k- ε and k- ω mo dels ar e supp orted. •For mo ving (tha t is, non-iner tial) r eference frame pr oblems , the single r eference frame (SRF) and multiple r eference frame (MRF) appr oaches ar e supp orted (as long as the absolut e velocity formu- lation is used), while the mixing plane mo del (MPM) is not. Note tha t for the MRF appr oach, the adjoin t solv er do es not supp ort ha ving a z one with a fr ame of motion tha t is r elative to an alr eady moving r eference frame . •Solid z ones ar e supp orted, as long as the y do not use a mo ving r eference frame appr oach. •By default , the adjoin t solv er uses spa tial discr etiza tion metho ds tha t are chosen f or stabilit y. If desir ed, you c an selec t mor e accur ate metho ds, as descr ibed in Using the A djoin t Solution M etho ds Dialog Box (p.3131 ). •The b oundar y conditions ar e only of the f ollowing t ypes: –Wall (not including thin w alls or shells) 3121Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the A djoin t Solver–Velocity inlet –Mass-flo w inlet –Mass-flo w outlet –Pressur e inlet –Pressur e outlet –Pressur e far-field –Symmetr y –Rotational and tr ansla tion p eriodic •Constan t and user-defined sour ces ar e supp orted f or the momen tum and ener gy equa tions; for details on the la tter, see User-D efined S ources (p.3123 ). Note tha t temp erature dep endenc y is not taken in to acc oun t with the adjoin t solv er. It is imp ortant to not e tha t these r equir emen ts ar e not str ict conditions f or the c onventional flo w solv er, but r ather mo deling limita tions f or the adjoin t solv er. When the adjoin t solv er is initializ ed or an obser vable is e valua ted, and b efore iterations ar e performed , a ser ies of checks is p erformed t o det ermine the suitabilit y of the e xisting flo w solution f or analy sis with the adjoin t solv er.Two types of message ma y app ear: •Warning message: There are certain ph ysics mo dels and b oundar y condition t ypes tha t are not e xplicitly modeled in the adjoin t solv er, but their absenc e do es not disallo w you fr om pr oceeding with the c alcula tion. In this c ase, a w arning message will b e pr inted tha t explains the na ture of the inc onsist ency. Checking adjoint setup... -- Warning: Model is active but not included in adjoint calculation: P1 radiation model Done The adjoin t solv er will still r un in this c ase but the qualit y of the adjoin t solution da ta can b e ex- pected t o be poorer as a r esult of the inc onsist ency.This is b ecause in such c ases the unsupp orted settings will r evert to corresponding supp orted settings f or the adjoin t solv er.Though the c alcula tion will pr oceed, it is imp ortant to not e tha t the r esults pr oduced should b e consider ed on this basis . When r everting back t o the fluid c alcula tion, the or iginal settings will b e pr eser ved and the mo dified settings ar e not migr ated on to the or iginal c ase.The w arning indic ates tha t the setting change will be made aut oma tically and sp ecific ally f or the adjoin t solution. •Error message: There are some mo del and b oundar y conditions tha t are inc ompa tible with the c omputa tion of an adjoin t solution with the cur rent adjoin t solv er implemen tation. In this c ase, an e xplana tory error message will b e pr inted in the c onsole windo w. Checking adjoint setup... ** Unable to proceed: Model is active but not compatible with adjoint calculation: Transition SST turbulence model Done The adjoin t solv er will not r un in this c ase and changes must b e made manually t o the settings iden tified in the c onsole b efore the solv er can b e run. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3122Design A naly sis and Optimiza tion44.2.1.2. User -Defined S our ces User-defined sour ces for the momen tum and/or ener gy equa tions tha t are defined in c ompiled UDFs can b e acc oun ted f or in the applic ation of the adjoin t solv er, provided tha t the sour ce der ivatives with r espect to flo w variables and c ell c entroid c oordina tes ar e pr ovided .This is achie ved b y creating the sour ce term UDF definition in the usual fashion, with the e xception tha t a sp ecial UDF macr o is used ,DEFINE_SOURCE_AE (The suffix _AE denot es A djoin t Enabled). DEFINE_SOURCE_AE (name ,c,t,dS,eqn ) Descr iption Argumen t Type UDF name symbol name Inde x tha t iden tifies c ell on which the sour ce term is t o be appliedcell_t c Pointer to cell thr ead Thread *t Array tha t contains the der ivative of the sour ce term with r espect to the dep enden treal dS[] variable of the tr ansp ort equa tion, as w ell as the flo w variables and c ell c entroid p osition Equa tion numb er int eqn Func tion r etur ns real Consider a sour ce tha t ma y dep end on v elocity, pressur e, and c ell-c entroid c oordina tes: wher e , , and are the C artesian v elocity comp onen ts in the c ell, is the pr essur e in the c ell, and are the c ell c entroid c oordina tes as defined b y the C_CENTROID macr o. If the sour ce strength dep ends on one or mor e of these quan tities , then the der ivatives of the sour ce str ength with r espect to those v ariables must b e comput ed and filled in as en tries t o the dS[] array. In par- ticular , 3123Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the A djoin t Solvermust b e defined in the UDF if ther e is a dep endenc y of the sour ce up on them. The sp ecific ation of this der ivative inf ormation is essen tial f or sensitivities , including shap e sensitivit y, to be comput ed correctly b y the adjoin t solv er. 44.2.2. Defining O bser vables Defining an obser vable is a k ey initial st ep tha t must b e performed f or an y adjoin t calcula tion. The obser vable is the quan tity for which sensitivities ar e sough t. Obser vables c an b e defined based on flow variables , or as op erations on other obser vables . For a list of the t ypes of obser vables y ou c an define r efer to Gener al O bser vables (p.3107 ) and Gener al Op erations (p.3111 ).You c an define multiple obser vables , but only one obser vable a t a time c an b e selec ted f or the adjoin t sensitivit y calcula tion. Obser vables ar e created and selec ted in the Adjoin t Obser vables dialo g box, which is acc essed b y click ing Obser vable ... in the Design ribbon tab ( Adjoin t-Based group b ox). (Figur e 44.1: Adjoin t Ob- servables D ialog Box (p.3124 )). Design → Adjoin t-Based → Obser vable ... Figur e 44.1: Adjoin t Obser vables D ialo g Box For mor e inf ormation, see the f ollowing sec tions: 44.2.2.1. Creating N ew O bser vables 44.2.2.2. Editing O bser vable D efinitions 44.2.2.3. Selec ting an O bser vable f or Sensitivit y Calcula tion 44.2.2.1. Creating N ew O bser vables You c an cr eate a new obser vable b y click ing Manage ... in the Adjoin t Obser vables dialo g box and then Create... in the Manage A djoin t Obser vables dialo g box. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3124Design A naly sis and Optimiza tionIn the Create New O bser vable dialo g box (Figur e 44.2: Create New O bser vable D ialog Box (O bser vable Types) (p.3125 )) you c an cho ose fr om se veral obser vable t ypes and op eration t ypes.Various t ypes of obser vable quan tities c an b e defined and each c an b e giv en a name .The a vailable t ypes of obser vables are descr ibed in Gener al O bser vables (p.3107 ). Figur e 44.2: Create New O bser vable D ialo g Box (O bser vable Types) Selec t Obser vable t ypes and pick an obser vable fr om the list. Keep the default name , or use the Name field t o designa te a diff erent name f or the obser vable of in terest. Click OK to cr eate the new obser vable , or click Canc el to dismiss the dialo g box without cr eating an obser vable . You c an also c ombine e xisting obser vables in v arious w ays or apply unar y op erations t o cr eate a wide variety of c omp ound obser vables .The op erations tha t you c an apply t o existing obser vables ar e de- scribed in Gener al Op erations (p.3111 ). 3125Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the A djoin t SolverFigur e 44.3: Create New O bser vable D ialo g Box (Op eration Types) Selec t Operation t ypes and cho ose an op eration fr om the list. Keep the default name , or use the Name field t o designa te a diff erent name f or the obser vable of in terest. Click OK to cr eate the new obser vable , or click Canc el to dismiss the dialo g box without cr eating an obser vable . Onc e created, you must edit the definition of the new obser vable ( Editing O bser vable D efini- tions (p.3126 )). 44.2.2.2. Editing O bser vable D efinitions Onc e an obser vable is cr eated, it app ears in the Obser vables list. When y ou selec t an obser vable in the Obser vables list, the Manage A djoin t Obser vables dialo g box changes t o expose v arious properties tha t can b e assigned f or the selec ted obser vable . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3126Design A naly sis and Optimiza tionFigur e 44.4: Manage A djoin t Obser vables D ialo g Box Onc e the obser vable pr operties ar e defined ( Inputs f or O bser vable Types (p.3128 )), click Apply to apply the settings and pr oceed t o define other obser vables , or click OK in the Manage A djoin t Obser vables dialo g box to apply the settings and close the dialo g box. Available obser vables ar e descr ibed in Gener al O bser vables (p.3107 ). Note It is p ermissible t o lea ve obser vable definitions inc omplet e.The Manage A djoin t Obser vables dialo g box can b e consider ed as a w orkspac e for the definition and manipula tion of obser vables . Only those op erations with c omplet e definitions will app ear in the Adjoin t Obser vables dialo g box. Operations with undefined fields , or operations tha t dep end on themselv es, will b e excluded fr om the list of usable obser v- ables . 3127Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the A djoin t SolverInputs f or O bser vable Types The inputs f or each t ype of obser vable ar e summar ized b elow: •For a force obser vable: 1.Selec t the w alls tha t are to contribut e to the f orce of in terest in the Wall Z ones list. 2.Define the dir ection in which the f orce is t o be comput ed b y en tering the c omp onen ts of this direction in the X Comp onen t,Y Comp onen t, and Z Comp onen t (for 3D) fields . •For a momen t of f orce obser vable: 1.Selec t the X,Y, and Z (for 3D) c omp onen ts of the Momen t Center. 2.Selec t the X,Y, and Z (for 3D) c omp onen ts of the Momen t Axis. 3.Selec t a w all in the Wall Z ones list. •For a swir l obser vable: 1.Selec t the X,Y, and Z (for 3D) c omp onen ts of the Swirl Center. 2.Selec t the X,Y, and Z (for 3D) c omp onen ts of the Swirl Axis. 3.Selec t a fluid in the Fluid Z ones list. •For a pressur e-dr op obser vable: 1.Selec t the inlets and outlets b etween which the t otal pr essur e dr op is t o be comput ed using the Inlets and Outlets lists . •For a fixed v alue obser vable , perform the f ollowing: 1.Selec t the Value of the Constan t. •For a surface-in tegral obser vable: 1.Selec t the t ype of in tegral from the Integral Type drop-do wn list. Available in tegral types ar e descr ibed in Gener al O bser vables (p.3107 ). 2.Selec t a Surface and the c orresponding Field Variable . •For a volume-in tegral obser vable: 1.Selec t the t ype of in tegral from the Volume In tegral Type drop-do wn list. Available in tegral types ar e descr ibed in Gener al O bser vables (p.3107 ). 2.Selec t the Field Variable of in terest. If the chosen field v ariable is a v ector quan tity, you will need to sp ecify a Direction along which the field v ariable will b e evalua ted. 3.Under Integration D omain , selec t whether t o in tegrate over selec ted Zones , a Box Region , or a Cell Regist er. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3128Design A naly sis and Optimiza tion4.Selec t the Zones for in tegration, enter the c oordina tes of the r ectangular (in 2D) or he xa- hedr al (in 3D) in tegration r egion under Box Settings , or mak e a selec tion fr om the Cell Regist er drop-do wn list. •For a ratio obser vable: 1.Selec t an obser vable fr om the Numer ator drop-do wn list t o represen t the numer ator of the r atio. 2.Selec t an obser vable fr om the Denomina tor drop-do wn list t o represen t the denomina tor of the ratio. •For a produc t obser vable: 1.Selec t two obser vables fr om the c orresponding dr op-do wn list tha t will b e used t o comput e their produc t. •For a linear c ombina tion obser vable: 1.Under Linear C ombina tion of p owers, selec t a Constan t value . 2.Selec t the numb er of Comp onen ts. 3.For each c omp onen t, selec t a c orresponding Coefficien t, an Obser vable , and a Power. •For an arithmetic a verage obser vable: 1.Selec t the numb er of Comp onen ts. 2.Selec t obser vables fr om the c orresponding Obser vable lists . •For a mean v arianc e obser vable: 1.Selec t the numb er of Comp onen ts. 2.Selec t obser vables fr om the c orresponding Obser vable lists . •For a unar y op eration obser vable: 1.Selec t an op eration fr om the dr op-do wn list (see Gener al O bser vables (p.3107 ) for a list of a vailable operators). 2.Selec t an obser vable fr om the c orresponding dr op-do wn list up on which the unar y op eration is to be applied . 3129Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the A djoin t Solver44.2.2.3. Selec ting an O bser vable for S ensitivit y Calculation Figur e 44.5: Adjoin t Obser vables D ialo g Box You c an selec t which obser vable t o use f or the sensitivit y calcula tion in the list of Obser vable N ames . Note •Only one obser vable c an b e used in an y one adjoin t calcula tion. In the Adjoin t Obser v- ables dialo g box, the obser vable tha t is cur rently highligh ted is the obser vable tha t will be used in the sensitivit y calcula tion. •Any obser vables tha t ha ve been cr eated but which ar e missing r equir ed inputs will not app ear in the list of Obser vable N ames . Clicking the Evalua te butt on c omput es the cur rent value of the selec ted obser vable quan tity and prints the r esult in the c onsole windo w. Clicking the Write... butt on pr ovides the option t o wr ite the result t o a named file . The Sensitivit y Or ientation det ermines the sign of the p ostpr ocessed sensitivities . For instanc e, if you selec t Maximiz e then changes in the dir ection of p ositiv e sensitivities will incr ease the v alue of the obser vable . A standar d rule of thumb c an b e applied: if y ou w ant to impr ove the solution, then follow the dir ection of the sensitivit y vectors. Another standar d rule of thumb c an also b e applied for p ostpr ocessed sc alars: if y ou w ant to impr ove the solution, then incr ease v alues wher e the sensit- ivity is p ositiv e and/or decr ease v alues wher e the sensitivit y is nega tive. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3130Design A naly sis and Optimiza tion44.2.3. Solving the A djoin t Onc e an obser vable is defined as descr ibed in Defining O bser vables (p.3124 ), the solution of the adjoin t for tha t obser vable c an b e comput ed based on the cur rent flo w solution. The st eps f or solving the adjoin t are similar t o those f or solving the flo w and ar e detailed in the f ollowing sec tions: 44.2.3.1. Using the A djoin t Solution M etho ds D ialog Box 44.2.3.2. Using the A djoin t Solution C ontrols D ialog Box 44.2.3.3. Working with A djoin t Residual M onit ors 44.2.3.4. Running the A djoin t Calcula tion 44.2.3.1. Using the A djoint S olution Metho ds D ialo g Box You c an sp ecify the metho ds used f or c omputing the adjoin t solutions in the Adjoin t Solution Metho ds dialo g box.To op en the Adjoin t Solution M etho ds dialo g box, click Metho ds... in the Design ribbon tab ( Adjoin t-Based group b ox). Design → Adjoin t-Based → Metho ds... Figur e 44.6: Adjoin t Solution M etho ds D ialo g Box The Adjoin t Solution M etho ds dialo g box sho ws a side-b y-side c ompar ison of the schemes used for the flo w solv er and f or the adjoin t solv er. Using the same scheme f or the adjoin t solution and the flow solution yields the most accur ate discr ete der ivative calcula tion when the adjoin t solution is converged . However, not all schemes used f or the flo w solv er ar e supp orted f or the adjoin t solv er. In these c ases an alt ernate adjoin t scheme must b e used .This do es not t ypic ally lead t o se vere det eri- oration of the adjoin t results qualit y. Even if the same scheme is a vailable f or the adjoin t solv er this is not alw ays pr actical b ecause stabilit y ma y be reduc ed with some schemes .Therefore, you c an use the dr op-do wn lists under Adjoin t Solver to selec t alt ernate schemes as needed . In some c ases it ma y not b e desir able t o solv e the ener gy adjoin t even if ener gy is solv ed in the flo w solv er. For e xample , consider an inc ompr essible flo w wher e the sp ecified obser vable do es not in volve ther mal quan tities . In this c ase the adjoin t for the ener gy equa tion is iden tically z ero, but its inclusion would add an unnec essar y numer ical bur den. You c an disable the Adjoin t Energy option t o avoid solving the ener gy adjoin t. 3131Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the A djoin t SolverIf the pr imar y flo w is a c ompr essible ideal gas , you c an sp ecify tha t the ph ysics of the c ompr essible flow ar e mo deled in the adjoin t solv er b y enabling the Adjoin t Ideal G as option. Enabling this option automa tically enables the Adjoin t Energy option as w ell. If the flo w is not a c ompr essible ideal gas , it will b e treated as b eing inc ompr essible f or the pur poses of the adjoin t calcula tion. Clicking Default will set the spa tial discr etiza tion metho ds for the adjoin t solv er to Green-G auss C ell Based for gr adien t,Standar d for pr essur e, and First Or der U pwind for momen tum, which ar e chosen for their stabilit y. Clicking Best M atch will a ttempt t o ma tch the adjoin t schemes t o the flo w schemes that should in gener al pr ovide mor e accur ate calcula tions a t convergenc e.Where the y cannot b e matched , the default scheme will b e used . 44.2.3.2. Using the A djoint S olution C ontr ols D ialo g Box The ad vancemen t of the adjoin t solution t o reach a c onverged solution is an essen tial par t of the analy sis.The solution algor ithm f or the adjoin t solv er is similar t o the c oupled pr essur e-based solv er that is a vailable f or c onventional flo w computa tions in ANSY S Fluen t. By default , the adjoin t solv er ad vancemen t settings will b e aut oma tically adjust ed dur ing c alcula tion to enc ourage c onvergenc e, with initial v alues det ermined b y the sta te of the flo w solution. If needed , you c an adjust the ad vancemen t controls in the Adjoin t Solution C ontrols dialo g box. To op en the Adjoin t Solution C ontrols dialo g box, click Solver C ontrols... in the Design ribbon tab (Adjoin t-Based group b ox). Design → Adjoin t-Based → Solver C ontrols... Controls Solution-B ased C ontrols Initializa tion When enabled , the ad vancemen t controls ar e selec ted aut oma tically when the adjoin t solution is initializ ed based on the sta te of the flo w. Stabiliza tion S ettings ... This butt on op ens the Stabiliz ed Scheme & S trategy Settings dialo g box, which y ou c an use t o define the stabiliza tion str ategy, scheme(s), and settings f or the adjoin t solution. For details , see Stabiliza tion Strategies , Schemes , and S ettings (p.3134 ). Auto-A djust C ontrols When enabled , the c onvergenc e of the AMG solv er and the adjoin t residuals ar e monit ored dur ing solution ad vancemen t. Based on the tr ends obser ved, the C ourant numb er is aut oma tically adjust ed to enc ourage r eliable solution ad vancemen t and c onvergenc e.This is esp ecially useful when a Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3132Design A naly sis and Optimiza tionnew t ype of pr oblem is b eing solv ed f or which appr opriate settings ar e not initially clear .You can enable or disable Auto-A djust C ontrols at an y time dur ing the solution. The C ourant numb er star ts at the v alue y ou defined in the Advanc emen t Controls group b ox or the v alue det ermined b y the Solution-B ased C ontrols Initializa tion option. When the r esidual minimiza tion scheme is used , over the first t wo iterations the C ourant numb er will b e incr eased as high as p ossible (while still allo wing the AMG solv er to converge), and will then r emain un- changed; for all other setups , the C ourant numb er will b e adjust ed t o ensur e the AMG solv er converges, with the goal of r educing the AMG r esiduals a t the r ate of 1 or der of magnitude o ver 6-8 it erations . Messages will app ear as the c alcula tion pr ogresses indic ating the adjustmen ts tha t are being made . Show A dvanc emen t Controls This option t oggles the visibilit y of the v arious ad vancemen t controls f or dir ect user sp ecific ation. Advanc emen t Controls contains the ad vancemen t controls. Apply P reconditioning Enables solution pr econditioning .This is needed f or most c ases in volving turbulen t flo w. If precon- ditioning is enabled , additional c ontrols ar e available . Cour ant Numb er A higher numb er corresponds t o a mor e aggr essiv e ad vancemen t of the c omputa tion a t the r isk of instabilit y. Disabling pr econditioning c orresponds t o an infinit e Courant numb er. Artificial C ompr essibilit y A nonz ero value in troduces ar tificial c ompr essibilit y into the c omputa tion of the adjoin t continuit y equa tion. A value of 1.0 or less is r easonable . Flow R ate Cour ant Sc aling ,Energy Equa tion Sc aling These v alues should b e lar ger than z ero (default v alue is 0.05 for flo w rate and 1 for ener gy). A smaller v alue implies a less aggr essiv e algor ithm tha t enc ourages stabilit y of the AMG linear solv er. Under-Relaxa tion F actors contains the under-r elaxa tion fac tors. 3133Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the A djoin t SolverAdjoin t Momen tum ,Adjoin t Continuit y,Adjoin t Local F low R ate,Adjoin t Energy Each of these c an b e set t o a v alue b etween 0.0 to 1.0 . A higher v alue leads t o a mor e aggr essiv e algor ithm tha t is less lik ely t o be stable . A value of 1.0 for each c an b e used f or some simple c ases without difficult y. Algebr aic M ultigr id contains the algebr aic multigr id controls. Toler anc e The t oler ance used f or judging c onvergenc e. Maximum I terations The maximum numb er of inner it erations of the AMG solv er. Show Iterations If enabled , a mor e verbose it eration hist ory is pr inted in the t ext console dur ing it erations .The details of the inner it eration c an b e useful when deciding on appr opriate Cour ant Numb er,Artificial Compr essibilit y, and Flow R ate Cour ant Sc aling . If man y inner it erations ar e needed , or if the inner iterations div erge, this signals tha t a r educ tion in Cour ant Numb er may be needed . Alternatively, an incr ease in Artificial C ompr essibilit y or a r educ tion in the Flow R ate Cour ant Sc aling may be sufficien t for the AMG it erations t o converge. 44.2.3.2.1. Stabilization Str ategies , Schemes , and S ettings For an o verview of when stabiliza tion is needed and descr iptions of the a vailable schemes , see Adjoin t Solver S tabiliza tion (p.3116 ).You c an define a stabiliza tion str ategy in the Stabiliz ed Scheme & Strategy Settings dialo g box, which is op ened b y click ing the Stabiliza tion S ettings ... butt on in the Adjoin t Solution C ontrols dialo g box. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3134Design A naly sis and Optimiza tionFigur e 44.7: The S tabiliz ed Scheme & S trategy Settings D ialo g Box Selec ting None from the Type list in the Stabiliza tion S trategy group b ox on the lef t allo ws you to selec t a single stabiliza tion metho d to be used thr oughout the c alcula tion, or none a t all. You specify y our pr eference using the Type list in the Stabiliza tion Scheme group b ox on the r ight and then define the scheme settings using c ontrols b elow the list. Alternatively, you c an selec t Blended from the Type list in the Stabiliza tion S trategy group b ox on the lef t, so tha t either no scheme ( None ) or the Dissipa tion scheme is applied a t the b eginning of the c alcula tion, dep ending on y our selec tion fr om the Scheme drop-do wn list in the 1st Scheme group b ox; then a sec ond scheme (the r esidual minimiza tion scheme) is used f or the r emainder of the c alcula tion. If you enable the Auto D etection? option, the first scheme will b e used un til div er- genc e or slo w convergenc e in the adjoin t residual is det ected; other wise , you sp ecify an e xplicit numb er of Iterations to be run b efore swit ching t o the sec ond scheme .The la tter can b e useful f or cases tha t tak e a long time t o div erge or sho w signs of slo w convergenc e with the first scheme , as you c an f orce an ear ly swit ch t o the r esidual minimiza tion scheme (which gener ally c onverges quick ly).You c an also sp ecify the maximum numb er of Iterations to allo w for the 2nd Scheme , as the r esidual minimiza tion scheme c an b e expensiv e on a p er it eration basis . Note tha t settings used for the dissipa tion and r esidual minimiza tion schemes ar e defined in the Stabiliza tion Scheme group b ox on the r ight, by selec ting each scheme in tur n (fr om the Type list), and then using the controls b elow the list as descr ibed in the sec tions tha t follow. Note After y our first c alcula tion is c omplet e, the sec ond stabiliza tion scheme will b e used a t the star t of all subsequen t calcula tions , unless y ou click the Initializ e Strategy butt on in the Run A djoin t Calcula tion dialo g box pr ior t o calcula ting . Initializing the str ategy is recommended when ther e is an op eration tha t will c ause a r esidual jump (such as mor phing the mesh), as the first scheme c an r esolv e some of the mo des mor e efficien tly. When using the Blended strategy, not e tha t you c an use the Default butt on t o revert an y changes you ha ve made t o the settings .You c an also use the Comple x Case butt on t o use settings tha t are mor e appr opriate for c omple x cases tha t would b enefit fr om the initial use of the dissipa tion scheme to damp lo cal div erging mo des, before swit ching t o the r esidual minimiza tion scheme; not e tha t for 3135Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the A djoin t Solversome c ases , you ma y need t o incr ease the Iterations for the dissipa tion scheme or incr ease the damping fac tor in the Stabiliza tion Scheme group b ox (for e xample , to 100 ) to allo w the scheme to fully damp the mo des. The Stabiliza tion Scheme settings ar e descr ibed in the f ollowing sec tions: 44.2.3.2.1.1. Dissipa tion Scheme 44.2.3.2.1.2. Residual M inimiza tion Scheme 44.2.3.2.1.3. Spatial S tabiliza tion Scheme 44.2.3.2.1.4. Modal S tabiliza tion Scheme 44.2.3.2.1.1. Dissipation Scheme The dissipa tion scheme op erates b y introducing nonlinear damping str ategic ally in to the c alcula tion domain. The str ategy is in tended t o pr ovide minimal in tervention in or der t o damp the gr owth of instabilities tha t lead t o adjoin t solution div ergenc e. A mar ker is tr acked, based on the sta te of the adjoin t solution, and the damping is applied dir ectly t o the adjoin t solution in r egions wher e the mar ker b ecomes lar ge. Figur e 44.8: The D issipa tion Scheme S ettings After selec ting Dissipa tion from the Type list, you c an define the f ollowing settings: Damping F actor The o verall le vel of dissipa tion is pr oportional t o this v alue although the damping le vel is det ermined ultima tely thr ough a nonlinear pr ocess. Damping Relaxa tion The damping r elaxa tion c an b e used t o control the r ate at which the dissipa tion is up dated as the adjoin t solution pr ogresses . As you decr ease the v alue fr om 1, the r ate at which the dissipa tion is up dated is decr eased . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3136Design A naly sis and Optimiza tionDamping Or der The spa tial or der of the dissipa tion. A higher or der leads t o mor e intense and lo calized damping .This can t ypic ally b e set t o be one or der lar ger than the adjoin t calcula tion spa tial or der. Suppr ession As par t of the dissipa tion scheme , the gr owth of instabilities is st opp ed b y the eff ect of the dis- sipa tion; enabling the Suppr ession option ensur es tha t these undesir able pa tterns will then also decay as the c alcula tion pr ogresses . Since the or der of discr etiza tion of the dissipa tion scheme is usually set higher than the adjoin t, the formal or der of accur acy of the adjoin t solution is unaff ected b y the addition of dissipa tion. However, regions of in tense dissipa tion c an app ear f or some c ases when using this scheme .This c an sometimes app ear as isola ted sp ots and str eaks in the adjoin t solution on sur faces.The sc ale of these f eatures is such tha t the y are of ten easily smo othed dur ing p ostpr ocessing t o gener ated design changes . 44.2.3.2.1.2. Residual M inimization Scheme The r esidual minimiza tion scheme op erates b y building a K rylov subspac e and using it t o build a solution with minimum r esidual. Figur e 44.9: The Residual M inimiza tion Scheme S ettings After selec ting Residual M inimiza tion from the Type list, you c an define the f ollowing settings: Numb er of M odes This sp ecifies the numb er of mo des in the K rylov subspac e used t o appr oxima te the solution. Incr easing the numb er of mo des will incr ease the c onvergenc e and r educ e the final r esidual. The c onvergenc e rate ma y incr ease shar ply when the numb er of mo des is lar ger than a c ertain thr eshold . Note tha t the memor y needed f or this scheme is pr oportional t o (numb er of adjoin t equa tions) * (numb er of mo des + numb er of r ecycled mo des). You should ensur e tha t you ha ve enough memor y for the v alue y ou enter her e; an estima tion of the additional memor y needed a t the p eak is pr inted in the c onsole when you click Apply . 3137Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the A djoin t SolverShow E xpert Controls Enabling this option r eveals the e xpert controls descr ibed b elow, so tha t you c an adjust them fr om the default v alues . Numb er of Rec ycled M odes This sp ecifies the numb er of mo des tha t are selec ted, stored, and used f or the ne xt iteration t o sp eed up the c onvergenc e.The default v alue is a quar ter of the numb er of mo des. For the initial st ep of the r esidual minimiza tion scheme , the numb er of sub-it erations is equal to the numb er of mo des; for la ter st eps, it is the diff erence of the numb er of mo des and the numb er of r ecycled mo des.Therefore, incr easing the numb er of r ecycled mo des will r educ e the numb er of sub-it erations f or each main it eration; while this r elation is str aigh tforward, the eff ect on the o verall c onvergenc e ratio is not , as it is c ase dep enden t. AMG I terations This sp ecifies the fix ed numb er of AMG it erations in each sub-it eration. Incr easing the numb er ma y impr ove the o verall c onvergenc e, but it also incr eases the time f or each sub-it eration.T he r esidual minimiza tion scheme is unique in tha t it do es not r equir e the AMG solv er to reduc e the inner r esidual by at least one or der; it only r equir es tha t the AMG solv er not b e div erging . In fac t, a mor e aggr essiv e setting of pr econditioning ma y slo w do wn the inner AMG c onvergenc e, but impr ove the o verall out er loop c onvergenc e. Such an impr ovemen t can b e signific ant. Note The f ollowing tips c an b e helpful when using the r esidual minimiza tion scheme: •It is highly r ecommended tha t you first r un the adjoin t solv er without a stabiliza tion scheme un til the adjoin t residual star ts to div erge, and then enable the r esidual minim- ization scheme .The first r un damps out man y stable mo des in the adjoin t residual and reduc es the numb er of mo des r equir ed in the r esidual minimiza tion scheme . Note tha t this c an easily b e done b y selec ting the Blended strategy in the Stabiliza tion S trategy group b ox. •The o verall adjoin t residual will b e pr inted in the c onsole .The r esidual should either decr ease monot onic ally or stall within each main it eration or b etween main it erations . If you do not see such b ehavior, click the Initializ e Stabiliza tion butt on in the Run A djoin t Calcula tion dialo g box to initializ e the scheme . 44.2.3.2.1.3. Spatial Stabilization Scheme The spa tial scheme op erates b y iden tifying par ts of the domain wher e unstable gr owth is o ccur ring and applying a mor e stable scheme .The unstable mo de tr acking and handling is done in an aut o- mated manner . Several settings ar e exposed , but ar e recommended f or e xpert users only . To enable the spa tial stabiliza tion scheme and define the settings , use the f ollowing t ext command: adjoint → controls → stabilization The settings a vailable f or this scheme include the f ollowing .The first f our settings r elate to unstable mode tr acking and selec tion, while the ne xt thr ee pr ovide options f or the r esponse onc e a mo de is iden tified . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3138Design A naly sis and Optimiza tionTracking History Length defines the numb er of it erations tha t are emplo yed in the unstable mo de iden tification pr ocess. A range between 2 and 5 ma y be chosen. The longer the tr acking hist ory, the b etter the qualit y of the iden tific- ation pr ocess. Resolution Threshold defines a thr eshold f or the separ ation b etween mo des based on their amplitudes . A value of 0.1 implies that the sec ond most-dominan t mo de must b e 0.1 of the amplitude of the pr imar y mo de b efore an unstable mo de c an b e consider ed as b eing adequa tely r esolv ed. Coherence Threshold defines a thr eshold tha t must b e met f or the closeness of the mo de t o pur e exponen tial gr owth as the iterations pr ogress. A smaller numb er means tha t a tigh ter toler ance must b e met b efore an unstable mode is c onsider ed as ha ving b een iden tified . Growth Threshold defines the gr owth r ate thr eshold f or unstable mo des tha t must b e met b efore the algor ithm r esponds to the pr esenc e of the mo de.The gr owth thr eshold defines the numb er of it erations tha t would ha ve to tak e plac e for the mo de t o gr ow by one or der of magnitude .That is, a value of 0.01 signifies tha t a mode tha t would gr ow one or der of magnitude or mor e in 100 it erations will b e handled . A nega tive value f or this thr eshold is not r ecommended as multiple stable mo des ma y be tracked. Maximum Number of Cells defines a limit on the numb er of c ells f or which stabiliza tion will b e applied when an unstable mo de is located. Mode Amplitude Cutoff defines the fr action of the p eak mo de amplitude b eyond which c ells will b e included f or stabiliza tion. Solution Blending defines an under-r elaxa tion fac tor for blending the stabiliz ed par t of the scheme with the standar d advancemen t scheme . A default of 0.1 is chosen. The v alue should lie b etween 0 and 1. Print Mode Information (when enabled) leads t o details of the unstable mo de tr acking pr ocess b eing pr inted in the c onsole windo w.The following is an e xample of wha t is pr inted when a mo de is r esolv ed par tially : Mode present> Growth : 2.38166e-01 Coherence : 1.27858e+00 Resolution Threshold : 1.00000e-01 Resolution : 1.32611e-01 The f ollowing is an e xample of wha t is pr inted when a mo de b ecomes mor e fully r esolv ed: Mode present> Growth : 1.35318e-01 Coherence : 2.84133e-04 Resolution Threshold : 1.00000e-01 Resolution : 2.75312e-04 Growth Threshold : 5.60193e-02 Growth : 1.35318e-01 Coherence Threshold : 1.00000e-02 Coherence : 2.84133e-04 Local stabilization required: Instability detected in 5 cells The final line only app ears when a c oher ent and r esolv ed instabilit y has b een iden tified succ ess- fully . Subsequen tly, the solution ad vancemen t algor ithm aut oma tically adjusts t o elimina te this unstable b ehavior. Print Local Solve Residuals (when enabled) leads t o details of the r esiduals f or the lo cal solution pr ocess b eing pr inted in the console windo w. An example of wha t is pr inted is giv en b elow: 3139Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the A djoin t SolverIter Adjoint-continuity Adjoint-xMom Adjoint-yMom Adjoint-Flowrate .... 27 1.76334e-03 1.57503e-01 1.26984e-01 2.92618e-01 Local (%) 61.02095 57.41937 62.09185 99.99136 The p ercentage r esidual indic ates the fr action of the t otal r esidual tha t is asso ciated with the local solution pr ocess. 44.2.3.2.1.4. Mo dal Stabilization Scheme The b ehavior of the mo dal scheme is as f ollows. As the c alcula tion pr ogresses the solution is mon- itored f or unstable gr owing pa tterns or mo des as the adjoin t solution is c orrected b y the pr imar y advancemen t algor ithm. The first stage of the stabiliza tion scheme in volves a ligh tweigh t monit oring process t o scr een f or an y unstable pa tterns. If the c alcula tion is pr ogressing in a stable manner ther e is no indic ation e ven tha t the stabiliza tion scheme is op erating . If a c andida te instabilit y app ears then it is monit ored. In the e vent tha t unstable b ehavior tha t cannot b e handled b y the pr imar y advancemen t scheme b ecomes e viden t a mor e in tensiv e pr ocess is ac tivated. Unstable pa tterns ar e refined using a fix ed p oint iteration scheme so tha t the y can b e handled cleanly and ad vanced in a stable manner using an alt ernative to the pr imar y ad vancemen t scheme . To enable the mo dal stabiliza tion scheme and define the settings , use the f ollowing t ext command: adjoint → controls → stabilization The settings a vailable f or this scheme include the f ollowing: Coherence Threshold controls the pr eliminar y scr eening f or gr owth. It defines the thr eshold f or relative varianc e of gr owth between it erations a t which a mor e detailed sear ch is ac tivated. A smaller v alue will t end t o dela y the activation of the mor e detailed sear ch for unstable gr owth a t the r isk of allo wing unstable gr owth t o continue f or mor e iterations . Max. Fixed Point Iterations is the maximum numb er of it erations tak en t o refine the unstable pa ttern dur ing the mor e detailed sear ch. Mode Purity Threshold is the t oler ance for an acc eptable unstable pa ttern. A smaller v alue will lead t o a pur er unstable mo de being iden tified .This ma y occur a t the e xpense of a lar ger numb er of fix ed p oint iterations . If the pur ity threshold is not met af ter the maximum sp ecified numb er of it erations then the unstable pa ttern is rejec ted. Conjugate Pair Threshold is the thr eshold f or inclusion of a sec ond unstable mo de alongside a c andida te mo de, forming a c on- juga te pair .This c orresponds t o a pseudo-time-p eriodic instabilit y, versus pur ely e xponen tial gr owth. Such instabilities c an o ccur in some c ases . Incr easing this v alue will incr ease the o ccur rence of a sec ond mode b eing included . Maximum Number of Cells is the lar gest numb er of c ells allo wed f or an unstable pa ttern tha t will b e handled b y the stabiliza tion scheme .The pr oblema tic instabilities f or an adjoin t solv er ar e of ten lo calized in spac e to a small numb er of cells out of the en tire flo w domain. However, ther e can b e transien tly gr owing c orrections t o the adjoin t solution tha t masquer ade as unstable pa tterns.This c ell limit suppr esses such false pa tterns from c onsider ation. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3140Design A naly sis and Optimiza tionMode Norm Cutoff serves to iden tify the main b ody of an unstable pa ttern and e xclude the p eripher al spa tial par ts of the mode tha t are of small amplitude . If the nor m cut off w as set t o zero, all unstable mo des w ould in volve all c ells in the domain. Therefore, reducing this v alue incr eases the numb er of c ells tha t are included in an unstable mo de. Regularization acts to regular ize the ad vancemen t of the unstable mo de c omp onen ts.The stiffness of the adjoin t governing equa tions c an giv e rise t o difficult y in disc erning the unstable pa ttern from nearb y stable patterns. Incr easing the r egular ization t ends t o overcome this difficult y and adds stabilit y to the c alcu- lation a t the e xpense of p otentially slo wer convergenc e.Valid v alues ar e between 0 and 1. Print Mode Information enables pr inting of stabiliza tion inf ormation t o the c onsole . When using the mo dal stabiliza tion scheme , the f ollowing b ehavior c an b e obser ved: •When the pr imar y ad vancemen t scheme is pr oceeding in a stable manner , the stabiliza tion scheme will r emain idle and no output will b e gener ated. •When a c andida te unstable pa ttern app ears it will b e tracked and a message will app ear with inf orm- ation ab out the det ected mo de: Mode growth: 1.34390e+00 Coherence: 8.28546e-02 In the ab ove example , the message indic ates tha t an unstable pa ttern tha t grows by mor e than 34% in one it eration is pr esen t.The v alue of the Coherence corresponds t o the v arianc e in gr owth between it erations . •When a c andida te unstable pa ttern is iden tified tha t meets the c oher ence thr eshold , the sec ondar y refinemen t stage is ac tivated: Mode growth: 1.35752e+00 Coherence: 3.95870e-02 Growing pattern cell count: 929 Isolating new mode Iteration: 0 Growth rate: 1.42665e+00 Residual: 5.88196e-02 Iteration: 1 Growth rate: 1.41329e+00 Residual: 1.34600e-02 Iteration: 2 Growth rate: 1.41227e+00 Residual: 2.25348e-02 New growing mode with 597 cells If the gr owing pa ttern cell c oun t exceeds Maximum Number of Cells the r efinemen t procedur e is postp oned . Likewise , if af ter refinemen t the numb er of c ells in volved e xceeds the sp ecified limit the mo de is r ejec ted. Each it eration c orresponds t o a r efinemen t of the unstable pa ttern.The adjoin t solution itself is not ad vanced dur ing this pr ocess.The r esidual c orresponds t o the pur ity of the mode and must e ventually fall b elow the Mode Purity Threshold for the mo de t o be acc epted. A minimum of 3 it erations is tak en so tha t the o ccur rence or absenc e of a c onjuga te pair c an b e verified . •The pr esenc e of the sometimes violen t unstable gr owth tha t can o ccur giv es a jagged app earance to the adjoin t residual plots . However, the under lying tr end of the r esidual plots should c orrespond to a c onverging adjoin t solution pr ocess. The unstable pa tterns of solution ad vancemen t are sp ecific t o the flo w solution, choic e of discr etiz- ation schemes , and solution ad vancemen t controls f or the adjoin t solv er. If an y of these v alues changes , then the unstable mo dal pa tterns must b e recomput ed so tha t the stabiliza tion scheme will func tion t o full eff ect. In the e vent tha t an y of these par amet ers is changed and the adjoin t 3141Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the A djoin t Solversolution is r estar ted a mo de r ecalibr ation pr ocess will b e initia ted. It should b e not ed tha t if ther e are man y unstable mo des tha t ha ve been iden tified then this r ecalibr ation ma y tak e some time . In contrast, the pa tterns of unstable gr owth ar e not sp ecific t o the obser vable tha t has b een selec ted. Given tha t ther e is c omputa tional eff ort needed t o iden tify the instabilities , a separ ate initializa tion process is a vailable just f or the unstable mo dal pa tterns.This allo ws the adjoin t solution itself t o be initializ ed f or a new obser vable while r etaining the k nowledge of ho w to stabiliz e the solution ad- vancemen t. A much smo other pa th to solution f or the sec ond and subsequen t obser vables is then achie ved. 44.2.3.3. Work ing with A djoint R esidual Monit ors The pr ogress of the it erations of the adjoin t solv er and the monit oring of the c onvergenc e is c ontrolled in the Adjoin t Residual M onit ors dialo g box.This dialo g box is acc essed b y click ing Monit ors... in the Design ribbon tab ( Adjoin t-Based group b ox). Design → Adjoin t-Based → Monit ors... Figur e 44.10: Adjoin t Residual M onit ors D ialo g Box The st eps t o define the monit or b ehavior ar e as f ollows: 1.Decide whether or not the r esiduals ar e to be pr inted in the c onsole b y setting the Print to Console check b ox as desir ed. 2.Decide whether or not the r esiduals ar e to be plott ed in the main windo w by setting the Plot check b ox as desir ed. 3.Set the ID of the windo w in which the adjoin t residuals ar e to app ear in the Windo w field . 4.Set ho w man y iterations ar e to be sho wn in the r esidual cur ves tha t are plott ed in the Iterations t o Plot field . 5.Enable and/or disable those v alues tha t are to be used as cr iteria for convergenc e, and set the Criteria in each c ase.The options ar e to test the r esiduals f or the f ollowing equa tions: Adjoin t continuit y,Adjoin t velocity,Adjoin t local flo w rate, and/or Adjoin t ener gy. Click the OK or Apply butt ons t o confir m tha t the settings ar e acc eptable . Clicking Plot will c ause existing adjoin t residuals t o be plott ed in the main gr aphics windo w. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3142Design A naly sis and Optimiza tion44.2.3.4. Running the A djoint C alculation Initializa tion and e xecution of the adjoin t solv er is acc omplished in the Run A djoin t Calcula tion dialo g box.This dialo g box is acc essed b y click ing Calcula te... in the Design ribbon tab ( Adjoin t- Based group b ox). Design → Adjoin t-Based → Calcula te... Figur e 44.11: Run A djoin t Calcula tion D ialo g Box The func tion of this dialo g box is as f ollows: Initializ e sets the v alue of the adjoin t velocity and pr essur e to zero everywher e in the pr oblem domain. Initializ e Strategy initializ es the stabiliza tion str ategy, such tha t the first stabiliza tion scheme is used a t the star t of the ne xt calcula tion r ather than c ontinuing t o use the sec ond stabiliza tion scheme .This butt on is only a vailable when the blended stabiliza tion str ategy is used . For details , see Stabiliza tion S trategies , Schemes , and Settings (p.3134 ). Initializ e Stabiliza tion clears all of the unstable mo des tha t ha ve been iden tified in c alcula tions using the stabiliza tion scheme , but lea ves the adjoin t solution unchanged .This butt on is only a vailable when the r esidual minimiza tion scheme or mo dal scheme is enabled . Numb er of I terations sets the numb er of it erations f or the c alcula tion. Note tha t if y ou ar e using a blended stabiliza tion str ategy, the c alcula tion ma y end so oner if the t otal of the it erations y ou sp ecified in the Stabiliz ed Scheme & Strategy Settings dialo g box (descr ibed in Stabiliza tion S trategies , Schemes , and S ettings (p.3134 )) is less than the v alue y ou en ter her e. Calcula te advances the adjoin t solv er b y the Numb er of I terations specified in the adjac ent field . Depending on the monit or settings , the r esiduals ma y be pr inted in the c onsole and/or plott ed in the main gr aphics windo w. 3143Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the A djoin t Solver44.2.4. Postpr ocessing of A djoin t Solutions Adjoin t solution da ta can b e postpr ocessed so tha t it pr ovides b oth qualita tive and quan titative view s of the eff ect of man y types of change tha t ma y be imp osed on a sy stem. While shap e changes ar e often of par ticular in terest ther e is a v ery rich da ta set , one as lar ge as the or iginal flo w field , available for e xplor ation. Postpr ocessing t ools ar e pr ovided with the in tention of p ermitting the adjoin t da ta to be mined in such a w ay tha t it pr ovides useful supp orting inf ormation f or an engineer who is mak ing design decisions f or a sy stem, or has questions ab out the r eliabilit y of the or iginal flo w calcula tion. Since the ANSY S Fluen t adjoin t solv er is a discr ete adjoin t solv er, the pr imitiv e adjoin t solution da ta provides sensitivit y to changes c ell-wise f or the c omputa tional mesh. Normaliza tion of these r esults by the c ell v olume pr ovides a mesh-indep endent view in to the da ta set. Information r egar ding p ostpr ocessing the adjoin t solutions c an b e found in the f ollowing sec tions: 44.2.4.1. Field D ata 44.2.4.2. Scalar D ata 44.2.4.1. Field D ata Adjoin t solution da ta can b e postpr ocessed using standar d ANSY S Fluen t postpr ocessing t ools including contours , vectors, xy-plots , hist ograms , and sur face and v olume in tegrals. In the Contours dialo g box, under Sensitivities ..., you c an find the f ollowing fields: Magnitude of S ensitivit y to Body Forces (C ell Values) This field is the magnitude of the adjoin t velocity pr imitiv e field .This field c an b e interpreted as the magnitude of the sensitivit y of the obser vable t o body force per unit v olume . It can b e used t o iden tify r egions in the domain wher e small changes t o the momen tum balanc e in the flo w can ha ve a lar ge or small eff ect on the obser vable .This field is of ten obser ved t o be lar ge, for e xample , up- stream of a b ody for which dr ag sensitivit y is of in terest, with the field diminishing in the upstr eam direction. This indic ates the in terference eff ect for an objec t positioned a t various lo cations upstr eam of the objec t of in terest. Sensitivit y to Body Force X-C omp onen t (Cell Values) ,Sensitivit y to Body Force Y-C omp onen t (Cell Values) , and Sensitivit y to Body Force Z-C omp onen t (Cell Values) These ar e the c omp onen ts of the adjoin t velocity pr imitiv e field .These fields c an b e interpreted as the magnitude of the sensitivit y of the obser vable t o comp onen ts of a b ody force per unit v olume . Consider a b ody force distr ibution, expressed as a f orce per unit v olume .The v olume in tegral of the v ector pr oduc t of tha t distr ibution with the c omp onen ts of this field giv es a first-or der estima te of the net eff ect of the b ody force on the obser vation. Sensitivit y to M ass S our ces (C ell Values) This field is the pr imitiv e adjoin t pressur e field .This field c an b e interpreted as the sensitivit y of the obser vable with r espect to mass sour ces or sinks in the domain. Consider a mass sour ce / sink dis- tribution, expressed as mass flo w rate per unit v olume .The v olume in tegral of tha t distr ibution, weigh ted b y the lo cal value of this field , gives the eff ect of the sour ces / sinks on the obser vation. When plott ed on a b oundar y, this field indic ates the eff ect of the addition or r emo val of fluid fr om the domain up on the quan tity of in terest. It is imp ortant to not e tha t in this sc enar io the eff ect of the momen tum of the fluid tha t is added or r emo ved is not tak en in to acc oun t.The b oundar y velocity sensitivit y should b e plott ed if tha t eff ect is also of in terest. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3144Design A naly sis and Optimiza tionSensitivit y to Energy Sour ces (C ell Values) This field is a vailable when the ener gy adjoin t equa tion is solv ed and is the pr imitiv e adjoin t tem- perature field . It can b e interpreted as the sensitivit y of the obser vable with r espect to the ther mal ener gy sour ces or sinks p er unit v olume in the domain. Artificial D issipa tion This field is a vailable when the adjoin t dissipa tion stabiliza tion scheme is enabled and sho ws the location and amoun t of the nonlinear damping tha t has b een in troduced t o damp the gr owth of instabilities tha t lead t o adjoin t solution div ergenc e. Sensitivit y to Visc osit y This field sho ws the sensitivit y of the quan tity of in terest t o variations in the turbulen t eff ective viscosity for a turbulen t problem, or the laminar visc osity in a laminar c ase.The sensitivit y is nor mal- ized b y the c ell v olume t o acc oun t for cell siz e variations in the mesh. Shap e Sensitivit y M agnitude This field is the magnitude of the sensitivit y of the obser vable with r espect to a def ormation applied to the mesh (b oth b oundar y and in terior mesh). When plott ed on the sur face of a b ody the lo cations wher e this quan tity is lar ge indic ates wher e small changes t o the sur face shap e can ha ve a lar ge effect on the obser vable of in terest. If the shap e sensitivit y magnitude is small then the eff ect of shap e changes in this r egion c an b e expected t o ha ve a small eff ect on the obser vable of in terest. When viewing this field , it is of ten obser ved tha t the magnitude v aries b y man y or ders of magnitude . Contour plots will clear ly dr aw attention t o regions with the highest sensitivit y (of ten shar p edges and c orners). However, it should b e rememb ered tha t a r elatively small sur face mo vemen t tha t is distr ibut ed o ver a lar ge ar ea c an ha ve a cumula tive eff ect tha t is lar ge. Normal S hap e Sensitivit y This field sho ws the nor mal c omp onen t of the shap e sensitivit y. A p ositiv e value indic ates an or ient- ation dir ected in to the domain, while a nega tive value indic ates tha t the shap e sensitivit y is or iented outwards fr om the domain. This field elimina tes the c omp onen t of the v ector shap e sensitivit y field that lies in the plane of the w all. Normal Optimal D isplac emen t This field sho ws the nor mal c omp onen t of the optimal displac emen t comput ed fr om the adjoin t solution. This field is defined only f or p ortions of w alls lying within the c ontrol-volume sp ecified f or mor phing .The siz e of the optimal displac emen t is det ermined b y the sc ale fac tor tha t is chosen f or the mor phing . A p ositiv e value of displac emen t indic ates tha t the sur face will b e displac ed in to the flow domain, wher eas a nega tive value of displac emen t corresponds t o wall mo vemen t out wards from the flo w domain. This field elimina tes the c omp onen t of the optimal displac emen t vector tha t lies in the plane of the w all. log10(S hap e Sensitivit y M agnitude) In view of the lar ge r ange of v alues p ossible f or the shap e sensitivit y magnitude , a convenienc e func tion tha t plots of the magnitude is pr ovided .This allo ws the imp ortanc e of the sur faces in a domain t o be ranked mor e easily based on ho w the y aff ect the obser vation of in terest when they are reshap ed. Shap e Sensitivit y X-C omp onen t,Shap e Sensitivit y Y-C omp onen t, and Shap e Sensitivit y Z-C om- ponen t (in 3D) fields These fields ar e the individual c omp onen ts of the sensitivit y of the obser vable of in terest with r espect to the mesh no de lo cations . It is plott ed as c ell da ta and is c omput ed as the a verage of the no dal sensitivities f or a giv en c ell, divided b y the c ell v olume . Note tha t for this discr ete adjoin t solv er the sensitivit y of the r esult with r espect to no de lo cations b oth on and off b oundar ies is c omput ed.The 3145Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the A djoin t Solvernormaliza tion b y cell v olume indic ates tha t the fields tha t are plott ed ar e the w eigh ting fac tors f or a continuous spa tial def ormation field . (Note tha t the no dal sensitivit y da ta itself is used when mesh mor phing is p erformed , and pr edic tions ab out the eff ect of shap e changes ar e made .) Sensitivit y to Boundar y X-V elocity,Sensitivit y to Boundar y Y-V elocity, and Sensitivit y to Boundar y Z-V elocity (in 3D) fields These fields ar e defined on those b oundar ies wher e a user-sp ecific ation of a b oundar y velocity is made f or the or iginal flo w calcula tion. This includes no-slip w alls.The field sho ws ho w sensitiv e the obser vable of in terest is t o changes in the b oundar y velocity at an y point. It is in teresting t o not e that even though the or iginal b oundar y condition sp ecific ation ma y be for a unif orm velocity on the domain b oundar y, the eff ect of a non-unif orm velocity perturba tion is a vailable .The eff ect of any sp ecific b oundar y velocity change c an b e estima ted as an in tegral of the v ector pr oduc t of the change t o the v elocity with the plott ed sensitivit y field . A plot of this quan tity on a v elocity inlet , for e xample , can b e very useful f or assessing whether or not the inlet is p ositioned t oo close t o key parts of the sy stem. That is, it addr esses the question of whether or not the flo w domain is t oo small to achie ve a succ essful c omputa tion of the p erformanc e measur e of in terest.Viewing this field will also indic ate whether or not the assumption of a unif orm inflo w is adequa te. Sensitivit y to Boundar y Pressur e This field is defined on b oundar ies wher e ther e is a user-sp ecified pr essur e as par t of a b oundar y condition, such as on a pr essur e outlet. The field sho ws the sensitivit y of the obser vation of in terest to variations in the b oundar y pr essur e acr oss the flo w boundar y. It is in teresting t o not e tha t even though the or iginal b oundar y condition sp ecific ation ma y be for a unif orm pr essur e on the domain boundar y, the eff ect of a non-unif orm pr essur e perturba tion is a vailable ,The eff ect of an y sp ecific boundar y pr essur e change c an b e estima ted as an in tegral of the pr oduc t of the change t o the pressur e with the plott ed sensitivit y field .Viewing this field will also indic ate whether or not the assumption of a unif orm pr essur e is adequa te for the simula tion. Sensitivit y to Boundar y Temp erature This field is a vailable when the ener gy adjoin t equa tion is solv ed and is defined on b oundar ies wher e a t emp erature boundar y condition is applied .This includes w alls, velocity inlets , mass- flow inlets , pressur e inlets , pressur e far-field b oundar ies, and pr essur e outlets wher e a backflo w temp erature ma y be sp ecified .The field sho ws the sensitivit y of the obser vation of in terest to variations in the b oundar y temp erature acr oss the b oundar ies. Note tha t even if the or i- ginal b oundar y condition sp ecific ation is f or a unif orm temp erature on the b oundar y, the effect of a non-unif orm temp erature perturba tion is a vailable .The eff ect of an y sp ecific boundar y temp erature change c an b e estima ted as an in tegral of the pr oduc t of the change to the t emp erature with the plott ed sensitivit y field .This field c an b e used t o indic ate whether or not the assumption of a unif orm temp erature is adequa te for the simula tion. Sensitivit y to Boundar y Heat Flux This field is a vailable when the adjoin t ener gy equa tion is solv ed and is defined on w alls wher e a heat flux b oundar y condition is imp osed .The field sho ws the sensitivit y of the obser vation of in terest to variations in the b oundar y hea t flux thr ough the w all. Its pr operties ar e analo gous t o those of Sensitivit y to Boundar y Temp erature. Sensitivit y to Flow Blo ckage This field is pr ovided as a c onvenien t tool for iden tifying p ortions of the flo w domain wher e the introduc tion of blo ckages or obstr uctions in the flo w can aff ect the obser vation of in terest. Consider a blo ckage in the flo w tha t gener ates a r eaction f orce on the flo w tha t is pr oportional t o the lo cal flow sp eed, and ac ting in the opp osite dir ection t o the lo cal flo w: wher e is a lo cal coefficien t for the r eaction f orce.The lo cal contribution of this f orce on the obser vation of in terest Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3146Design A naly sis and Optimiza tionis det ermined b y the v ector pr oduc t of this f orce with the adjoin t velocity field .The flo w blo ckage field tha t is plott ed is , namely the nega tive of the v ector pr oduc t of the flo w velocity and the adjoin t velocity (Cell Value). Adjoin t Local S olution M arker This field , intended f or e xpert users who ar e using the Spatial S tabiliza tion Scheme (p.3138 ), can b e plott ed t o iden tify those p ortions of the flo w domain wher e the stabiliz ed adjoin t solution ad vance- men t scheme is applied . It is pr eferable t o plot this with the Node Values disabled in the Contours dialo g box. In this c ase, the Adjoin t Local S olution M arker will tak e a v alue b etween 0 and 1. The Mode A mplitude C utoff defined in the Stabiliz ed Scheme S ettings dialo g box defines the lo wer bound f or cells wher e the stabiliz ed scheme is applied . The sur face shap e-sensitivit y fields c ontain the der ivatives of the chosen obser vable with r espect to the p osition of the b ounding w alls of the pr oblem. In the Vectors dialo g box, under Vectors of ..., you c an find the f ollowing cust om v ector fields: Sensitivit y to Body Forces(Cell Values) This v ector field sho ws ho w sensitiv e the obser vable of in terest is t o the pr esenc e of b ody forces within the flo w. A b ody force tha t locally has a c omp onen t in the dir ection of the b ody-force sensitivit y vector will lead t o an incr ease in the obser vation of in terest.The lar ger the sensitivit y vector, the lar ger the eff ect that a b ody force can ha ve on the obser vation of in terest.The first-or der eff ect of a b ody force distr ibution per unit v olume c an b e comput ed as a v olume in tegral of the v ector pr oduc t of the b ody force distr ibution with this field . Sensitivit y to Shap e field defined on w alls This v ector field sho ws the p ostpr ocessed adjoin t solution, indep enden t of an y mor phing settings , tha t defines the sensitivit y of the obser vable of in terest t o mo vemen t of the w alls. Deformation of a w all wher e this v ector is lar ge c an b e expected t o ha ve a signific ant eff ect on the obser vable . In c ontrast, deformations of the w all in lo cations wher e this v ector is small in magnitude , to first or der, will ha ve no effect on the obser vable . Optimal D isplac emen t The optimal displac emen t field is defined onc e a design change has b een c omput ed using the D esign Tool.This v ector field sho ws the optimal displac emen t based on the design goals tha t ha ve been sp ecified and an y pr escr ibed b oundar y motions . Note tha t when plotting this v ector field , if the Auto Sc ale option is deselec ted, and the v ector Scale option is set t o 1, then the v ectors as sho wn displa y the absolut e displac emen t tha t will o ccur . Sensitivit y to Boundar y Velocity This sensitivit y field is defined on b oundar ies wher e velocities ar e sp ecified as an input f or the b oundar y condition. This includes no-slip , and slip w alls.When plott ed, this field illustr ates wher e a change t o the boundar y velocity can aff ect the obser vation of in terest.When plott ed on a w all, it sho ws ho w the im- position of a nonz ero velocity condition on the w all will aff ect the obser vation. This c an include mo vemen t in the plane of the w all itself .When plott ed, for e xample on a v elocity inlet , this field illustr ates ho w local adjustmen ts to the v elocity of the inc oming flo w aff ect the obser vation of in terest. Integrating a potential change t o the v elocity field , weigh ted b y this sensitivit y field o ver the b oundar y pr ovides a first or der estima te of the eff ect of the change on the obser vation of in terest. Sensitivit y to Boundar y M ass F lux This sensitivit y field tha t can b e used t o visualiz e the eff ect of adding or r emo ving fluid via a w all-nor mal jet.This c an b e used , for e xample , to iden tify r egions on w alls wher e the in troduc tion of suc tion c ould have a signific ant eff ect on the obser vable tha t has b een sp ecified . A plot of the Sensitivit y to Boundar y Velocity in gener al pr ovides a r icher view , but sometimes a t the e xpense of the clar ity of the visualiza tion. 3147Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the A djoin t Solver44.2.4.2. Scalar D ata The c omput ed adjoin t solution c an pr ovide sensitivit y inf ormation f or individual b oundar y condition settings thr ough the Adjoin t Rep orting dialo g box.This dialo g box is acc essed b y click ing Rep orting ... in the Design ribbon tab ( Adjoin t-Based group b ox). Design → Adjoin t-Based → Rep orting ... Figur e 44.12: Adjoin t Rep orting D ialo g Box Boundar y condition sensitivit y da ta is r etrieved as f ollows: •Selec t a single b oundar y of the pr oblem in the Boundar y Choic e selec tion b ox. •Click Rep ort to see the b oundar y condition settings and the sensitivit y of the obser vable with r espect to those settings . An example of a r eport is sho wn b elow: Velocity inlet id 5 Velocity magnitude = 4.000000000e+01 (m/s), Sensitivity = 5.429127866e+01 ((n)/(m/s)) In this c ase, the r eport sho ws tha t for e very change of the b oundar y velocity by 1 m/s , a change in the pr edic ted obser vable (in this c ase a f orce) of 54.2 N is e xpected.This pr edic tion is based on a linear e xtrapolation. •Click Write... to wr ite the r eport for the selec ted b oundar y to a file . 44.2.5. Modifying the G eometr y Using the D esign Tool Tools t o mo dify the b oundar y and in terior mesh of the pr oblem based on the adjoin t solution ar e provided in the Design Tool dialo g box.The Design Tool uses c omput ed adjoin t sensitivit y da ta to find an optimal design change sa tisfying one or mor e goals or c onstr aints, and t o pr edic t the r esulting changes in obser vable v alues . Among the goals tha t can b e sp ecified in the Design Tool are: •minimiza tion, maximiza tion, or tar geted changes of single or multiple obser vable v alues Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3148Design A naly sis and Optimiza tion•prescr ibed f orms of def ormation f or selec ted geometr y •gener al constr aints on def ormations including r estrictions on dir ection of motion, symmetr y, and b oundar y conditions . •equalit y and/or inequalit y constr aints on geometr y (fix ed w alls, bounding b oxes, and so on). The Design Tool is acc essed b y click ing Design Tool... in the Design ribbon tab ( Adjoin t-Based group box). Design → Adjoin t-Based → Design Tool... Figur e 44.13: Design Tool D ialo g Box The gener al pr ocedur e to use the D esign Tool is as f ollows. 1. Selec t the appr opriate Morphing M etho d for y our pr oblem. In gener al, if y ou pr efer mesh qualit y over adher ence to the design c onditions , you should selec t Polynomials ; other wise , you should selec t Direct In terpolation . For details on ho w the y calcula te the displac emen t of the mesh no des and their r elative mer its, see Smoothing and M esh M orphing (p.3118 ). 2. Selec t those b oundar ies tha t are free t o be def ormed in the Zones To Be M odified field on the Design C hange tab . Boundar ies tha t are not selec ted in this b ox tha t intersec t the c ontrol volume 3149Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the A djoin t Solverwill b e constr ained not t o mo ve.This is useful if ther e ar e walls which, for design r easons , must not mo ve. Note •If you ha ve a t wo-sided w all tha t you w ant to def orm, it is r ecommended tha t you selec t both the w all and the c orresponding w all-shado w. •When using the Direct Interpolation mor phing metho d, you must ensur e tha t none of the z ones in volved in a non-c onformal mesh in terface are selec ted. 3. Define the r egion tha t will b e mo dified in the Region tab . (Defining the R egion f or the D esign Change (p.3151 )) 4. Define c onditions on the def ormation r egion such as numb er of c ontrol p oints, symmetr y, directional invarianc e, and b oundar y continuit y. (Defining R egion C onditions (p.3153 )) 5. Export the sensitivities fr om the adjoin t solution f or each obser vable of in terest. (Exporting S ensitivit y Data (p.3154 )) 6. Imp ort the sensitivit y da ta for each obser vable tha t will par ticipa te in the design change and sp ecify the optimiza tion goals f or the obser vables . (Defining O bser vable O bjec tives (p.3154 )) Note Export and Imp ort of sensitivit y da ta is only r equir ed f or multi-objec tive analy sis. 7. Define c onstr aining and/or def ormation c onditions on the design change , such as fix ed b oundar ies, prescr ibed f orms of b oundar y def ormation (thr ough a pr ofile , transla tion, rotation, scaling , or r igid body motion), and b ounding sur faces / planes . (Defining C onditions f or the D eformation (p.3155 )) 8. (optional) A djust the optimal design c alcula tion numer ics if r equir ed. (Design Tool N umer ics (p.3162 )) 9. Specify the design c onditions t o be applied (and whether the y are str ictly enf orced), the w eigh ts for the v arious objec tives, and the def ormation par amet ers; then c omput e the optimal design change and mo dify the mesh. (Shap e M odific ation (p.3164 )) Details of these st eps ar e elab orated in the f ollowing sec tions: 44.2.5.1. Defining the R egion f or the D esign C hange 44.2.5.2. Defining R egion C onditions 44.2.5.3. Exp orting S ensitivit y Data 44.2.5.4. Defining O bser vable O bjec tives 44.2.5.5. Defining C onditions f or the D eformation 44.2.5.6. Design Tool N umer ics 44.2.5.7. Shap e Modific ation Note tha t if y ou ar e setting up the Design Tool in pr epar ation t o use the Gradien t-Based Optimiz er, you will need t o perform most—but not nec essar ily all—of the pr evious st eps; for details , see Using the G radien t-Based Optimiz er (p.3168 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3150Design A naly sis and Optimiza tion44.2.5.1. Defining the R egion for the D esign C hange To define the r egion of spac e wher e a design change is t o be applied , perform the f ollowing st eps: 1. Click the Region tab of the Design Tool dialo g box. 2. Make a selec tion fr om the Region G eometr y drop-do wn menu t o sp ecify whether y ou will define the spac e as either a Cartesian or a Cylindr ical region t ype. 3. The Show B ounding Region option is enabled b y default , so tha t you c an view the r egion in the graphics windo w as it is defined . 4. The simplest w ay to set up the b ounding r egion is t o click the Get B ounds ... butt on. In the Bounding Region D efinition dialo g box tha t op ens, you c an selec t the Zones t o Be Bounded and click OK to define a r egion tha t enc ompasses those z ones .The following options ar e enabled in the Bounding Region D efinition dialo g box by default: •The Comf ortable Region option sp ecifies tha t the r egion is sligh tly lar ger than selec ted z ones .You can disable this option if y ou w ant the r egion t o exactly adher e to the e xtents of the selec ted z ones . •For the Cylindr ical region t ype, the Automa tic C oordina te option defines the or igin and axis of the region t o ma tch those defined f or the selec ted z ones (if p ossible). This is helpful when a selec ted zone has b een defined as r otationally p eriodic, or is adjac ent to a c ell z one tha t has the Frame M otion option enabled as par t of a r otating r eference frame pr oblem. If nec essar y, you c an then click the Larger Region and/or Smaller Region butt ons t o adjust the size of the r egion. 5. If you need mor e pr ecise c ontrol over the definition of the r egion, you c an en ter values dir ectly for the settings . For the Cartesian region t ype, you c an sp ecify the X M in,X M ax,Y M in, and Y M ax (and Z M in and Z M ax in 3D) fields . For the Cylindr ical region t ype, you c an sp ecify the angular , radial, and (f or 3D) axial c oordina te ranges; this will r equir e you t o define a Coordina te System, and then en ter the v alues of the Region E xtent relative to tha t system. The fields y ou will define ar e illustr ated in Figur e 44.14: A Cylindr ical Region (p.3152 ). 3151Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the A djoin t SolverFigur e 44.14: A C ylindr ical Region Note the f ollowing f or Cylindr ical regions: •For 2D c ases , the axis is defined implicitly as the Z-axis (as det ermined b y the r ight-hand r ule, wher e in a fr ont view the X-axis is hor izontal and the Y-axis is v ertical). •For the angular r ange (defined b y Theta M in and Theta M ax), the p ositiv e dir ection is det ermined by the r ight-hand r ule ab out the axis , and the t otal r ange must not e xceed 360 degr ees. •For 3D c ases , the axis and r adial dir ection must not b e co-linear . •Radial symmetr y is not p ossible . After y ou ha ve en tered the settings , click Update Region to set the v alues and up date the displa y. Note Symmetr y conditions aff ect the lo cation and siz e of the r egion: •If you plan t o enable the Symmetr y of M otion options in the Region C onditions tab (as descr ibed in Defining R egion C onditions (p.3153 )), the r egion should b e positioned with forethough t giv en t o the eff ect on the v arious b oundar y zones in the r egion. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3152Design A naly sis and Optimiza tion•If you ha ve a b oundar y zone of t ype symmetr y in the r egion, it is r ecommended tha t it either is lo cated on a planar b oundar y of the r egion, or is c entered within the r egion in a manner tha t is c onsist ent with the Symmetr y of M otion option. 44.2.5.2. Defining R egion C onditions To define the r egion c onditions , perform the f ollowing st eps. Note tha t all of the settings descr ibed in this sec tion (e xcept f or the Motion E nabled options) ar e either unnec essar y or not supp orted when using the dir ect interpolation metho d for mor phing , and ar e thus not a vailable f or editing . 1. Click the Region C onditions tab in the Design Tool dialo g box. 2. Specify the c ontrol p oints and motion c onditions f or each c oordina te dir ection. a. Selec t the numb er of c ontrol Points. The c ontrol p oints ar e distr ibut ed unif ormly within each c oordina te range (in the X-, Y-, and Z- dir ections f or a C artesian r egion, and the Theta, Radial, and A xial dir ections f or a c ylindr ical region). The spacing b etween the c ontrol p oints defines the char acteristic spa tial sc ale f or the def ormation op eration. The lar ger the numb er of c ontrol p oints, the smaller the spacing and henc e, the smaller the spa tial sc ale on which changes c an b e made . 20 t o 40 c ontrol points for each c oordina te dir ection is t ypic al. Note tha t the c ontrol p oints ar e displa yed in r ed (and up dated when y ou click Apply ) along represen tative dir ections of the r egion in the gr aphics windo w, in or der t o allo w you t o visually det ermine if the numb er y ou ha ve sp ecified is appr opriate. b.If you w ant to pr event def ormation in the giv en c oordina te dir ection, disable Motion E nabled . c.If you w ant the motion along a c oordina te dir ection t o be unif orm in one or mor e dir ections , enable the appr opriate option (f or e xample ,Invariant in X ). d.You c an ensur e tha t the def ormation is symmetr ical relative to the diff erent coordina te dir ections by enabling options in the Symmetr y of M otion group b ox. Symmetr y can b e imp osed in as man y directions as desir ed (though r adial symmetr y for a c ylindr ical region is not p ossible). The symmetr y planes will b e displa yed in the gr aphics windo w when y ou click Apply ; you should ensur e the y reflec t your in tent for the design change , mo difying the e xtents of the def ormation r egion as ne- cessar y. 3. The Region B oundar y Continuit y settings c ontrol the or der of c ontinuit y of the def ormation pr ocess at the b oundar ies of the def ormation r egion. This is of par ticular r elevance when the b oundar y of the deformation r egion in tersec ts a w all tha t will b e def ormed .The Continuit y Or der controls the smo othness of the tr ansition fr om the undef ormed w all lying outside the def ormation r egion t o the deformed w all within. A value of 1 ensur es first-or der c ontinuit y at the tr ansition, tha t is, a continuous first der ivative of the def ormation op eration. A value of 2 ensur es sec ond-or der c ontinuit y, and so on. By default , the c ontinuit y Definition is Uniform and is enf orced a t all def ormation r egion boundar ies. Alternatively, you c an cho ose By Boundar y to use diff erent continuit y conditions at each b oundar y. For each b oundar y (X-M in,X-M ax, and so on) y ou c an sp ecify wha t order continuit y to enf orce for each motion dir ection. You c an also sp ecify In-P lane M otion Only on 3153Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the A djoin t Solverthat boundar y; not e tha t this option ma y be useful if a def ormation r egion b oundar y coincides with a b oundar y zone tha t is of t ype symmetr y. The c ontinuit y settings will not aff ect the tr ansition b etween fix ed and mo vable b oundar ies within the def ormation r egion, only mesh no des in the tr ansition z one fr om inside t o outside the def ormation r egion. 4. Click Apply . 44.2.5.3. Exporting S ensitivit y Data In or der t o perform multi-objec tive optimiza tion, you need t o export the sensitivit y da ta for each obser vable/flo w-condition c ombina tion tha t will tak e par t in the optimiza tion. 1. Define the obser vables of in terest as descr ibed in Defining O bser vables (p.3124 ). 2. For each obser vable solv e for and e xport the sensitivit y da ta. a. Solve the adjoin t as descr ibed in Solving the A djoin t (p.3131 ). b.Click the Manage D ata... butt on in the Objec tives tab of the Design Tool dialo g box, and then click the Export... butt on in the Manage S ensitivit y Data dialo g box tha t op ens. The e xported file c ontains the sensitivities of the obser vable f or the mesh no des within the sp ecified deformation r egion. The def ormation r egions f or the v arious obser vables c an, in pr inciple , be diff erent. However, it is ad visable tha t ther e is as much o verlap as p ossible f or obser vables tha t will b e used together in a multi-objec tive design pr ocess. 44.2.5.4. Defining O bser vable O bjec tives The D esign Tool comput es the optimal mesh def ormation t o sa tisfy multiple simultaneous design goals . Among these c an b e goals f or multiple obser vables , possibly a t multiple flo w conditions . Onc e you ha ve obtained the adjoin t solutions and displac emen t sensitivities f or the v arious obser vables of interest, you c an imp ort the da ta and sp ecify the design objec tives for each. 1. Click the Objec tives tab in the Design Tool dialo g box. 2. To imp ort previously sa ved sensitivit y da ta, click Manage D ata... .Then click the Imp ort... butt on in the Manage S ensitivit y Data dialo g box tha t op ens t o load pr eviously sa ved sensitivit y files . Close the Manage S ensitivit y Data dialo g box when done . 3. If you w ant to include c omput ed sensitivit y da ta in the cur rent session tha t you ha ve not e xported y et enable Include C urrent Data. 4. For each obser vable objec tive you c an sp ecify the f ollowing . Objec tive determines ho w Fluen t will a ttempt t o change the v alue of the obser vable thr ough the design change .You c an cho ose t o incr ease or decr ease the v alue of the obser vable optimally , or y ou c an specify a tar get change in v alue .You c an also selec t None in which c ase the obser vable will not b e consider ed in c omputing the optimal design change , but the pr edic ted change in obser vable v alue will still b e reported. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3154Design A naly sis and Optimiza tionTarget/Ref erenc e Change When the chosen Objec tive is Target C hange in Value , this field c orresponds t o the desir ed change in the v alue .When the chosen Objec tive is Maximiz e or Minimiz e, the magnitude of this field is a reference weigh ting f or the obser vable .This c an b e used t o nor maliz e the objec tives in c ases wher e you ha ve multiple obser vables of v astly diff ering magnitudes , ther eby allo wing the v alues entered f or Weigh t in the Design C hange tab t o all b e of similar sc ale.You c an check As Percentage to sp ecify the Target/Ref erenc e Change as a p ercentage of the v alue of the obser vable . Note You must click Apply for each objec tive you define b efore mo ving on t o the ne xt one . 44.2.5.5. Defining C onditions for the D eformation In the Design C onditions tab , you c an sp ecify c onditions on the mesh mor phing such as fixing p ortions of w all sur faces, prescr ibing the def ormation of sur faces, or setting up b ounding planes / sur faces. To cr eate a c ondition, click Create..., selec t the t ype of c ondition in the Create New C ondition dialo g box (you c an cho ose b etween fixed-w alls,bounded-b y-plane ,bounded-b y-sur faces,prescr ibed- profile ,rotation ,transla tion ,scaling , and rigid-b ody), and pr ovide a unique Name .You c an then define the c ondition b y selec ting it in the Defined C onditions list on the lef t, defining the settings (as descr ibed in the st eps tha t follow), and click ing Apply . If nec essar y, you c an Rename a selec ted condition using the Rename C onstr aint dialo g box tha t op ens. Onc e created, the design c onditions can b e individually included or e xcluded fr om the design change in the Design C hange tab . At an y time y ou c an click the Displa y butt on so y ou c an view the sur faces of the selec ted design condition in the gr aphics windo w.The t ype of design c ondition is indic ated b y the c olor of the sur face. Clicking the Displa y Options ... butt on op ens the Design C ondition D ispla y Options dialo g box, wher e you c an set the f ollowing additional options: •The Auto-D ispla y option sp ecifies tha t the gr aphics windo w aut oma tically up dates whene ver a design condition is cr eated or selec ted, as w ell as when the Apply butt on is click ed. •The Schema tic option sp ecifies tha t settings f or the design c onditions ar e also displa yed in the gr aphics windo w, including or igins , axes, planes , and nor mals . •When using the Polynomials mor phing metho d, design c onditions ar e not applied t o every no de, but instead t o a subset of no des distr ibut ed thr oughout the selec ted sur faces; this is t o avoid o verly constr aining the z one .The Constr ained N odes option in the Design C ondition D ispla y Options dialo g box allo ws you t o highligh t the no des of this subset. This c an help y ou det ermine if the numb er of c ontrol Points defined in the Region C onditions tab / siz e of the r egion is appr opriate for the sur faces in volved in y our design c onditions; if the densit y of c onstr ained no des is not sufficien t, you should either incr ease the numb er of c ontrols p oints or r educ e the siz e of y our r egion. Note tha t the c onstr ained no des ar e only relevant for sur faces tha t are not selec ted in Figur e 44.18: The S trict Conditions D ialog Box (p.3165 ). 3155Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the A djoin t SolverFigur e 44.15: The D esign C ondition D ispla y Options D ialo g Box Note tha t the adjoin t solv er's pr edic tion r ange is r educ ed when y ou include design c onditions—es- pecially prescr ibed-pr ofile ,rotation ,transla tion ,scaling , and/or rigid-b ody conditions—so y ou should a ttempt smaller def ormations (f or e xample , when setting the Target/Ref erenc e Change in the Objec tives tab). Imp ortant A giv en sur face cannot ha ve multiple c onditions of t ype prescr ibed-pr ofile ,rotation , transla tion ,scaling , or rigid-b ody. Fixed Walls The fixed-w alls constr aint can b e applied t o clip-sur faces of w alls in the def ormation r egion. This offers a fine-gr ained c ontrol o ver par ts of the geometr y tha t should not mo ve.Whereas deselec ting a zone in the Zones To Be M odified list on the Design C hange tab will fix an en tire wall z one , se- lecting a clip-sur face from in the Fixed Walls C ondition list will fix only the p ortion of the w all tha t forms the clip-sur face. Any clip sur faces y ou ha ve defined will app ear in the Clip S urfaces list. You c an assign clip sur faces to a fix ed w alls c onstr aint by selec ting them in the list and click ing Apply . Bounding P lanes The bounded-b y-plane condition allo ws you t o define one or mor e bounding planes tha t constr ain the geometr y def ormation in such a w ay tha t the geometr y cannot cr oss the giv en planes , ther eby respecting pack aging or f orm-fac tor c onstr aints.The b ounding plane is char acterized b y a v ector normal t o the plane and a distanc e measur ed fr om the global c oordina te sy stem or igin t o the plane , along the nor mal dir ection. The motion of the selec ted w all sur face(s) will b e constr ained such tha t all p oints on the sur face(s) lie on the side of the b ounding plane tha t is opp osite to the nor mal dir ec- tion. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3156Design A naly sis and Optimiza tionFigur e 44.16: Specifying a B ounding P lane f or D esign C hanges Origin d<0wallsurfacebounding plane nr Origin d>0wallsurfacebounding plane nr In Figur e 44.16: Specifying a B ounding P lane f or D esign C hanges (p.3157 ) the b ounding plane nor mal vector is denot ed b y and the distanc e is denot ed b y . is the p osition v ector of a p oint on the wall sur face subjec t to the b ounded-b y-plane c ondition. Note tha t a p ositiv e value f or the distanc e yields a b ounding plane tha t is or iented with its nor mal p ointing a way from the or igin, while a neg- ative value f or the distanc e yields a b ounding plane or iented with its nor mal dir ection p ointing t owards the or igin. The c onstr aint equa tion c an b e expressed as: 1. Selec t the sur faces (or clip-sur faces) tha t are subjec t to the b ounding plane c ondition in the Bounded Surfaces list. 2. Enter the c omp onen ts of the b ounding plane nor mal dir ection. 3. Enter the distanc e of the plane fr om the or igin (along the nor mal dir ection). 4. Click Apply . Bounding S urfaces The bounded-b y-sur faces condition allo ws you t o imp ort one or mor e bounding sur faces tha t con- strain the geometr y def ormation in such a w ay tha t the geometr y cannot cr oss the near est fac et of the b ounding sur faces, ther eby respecting pack aging or f orm-fac tor c onstr aints; alternatively, you can pr escr ibe tha t the geometr y def orms t o conform to the b ounding sur faces.The b ounding sur faces can b e read fr om an .stl ,.msh , or .cas file.The def ormation of the selec ted b ounded sur faces will b e constr ained such tha t all p oints on the sur faces lie on the sides of the b ounding sur faces tha t have a p ositiv e or ientation. 1. Selec t the sur faces (or clip-sur faces) tha t are subjec t to the b ounded-b y-sur face condition in the Bounded Surfaces list. 2. Use the Read ... butt on t o imp ort a .stl ,.msh , or .cas file tha t contains the appr opriate bounding surface(s). Note tha t the file y ou r ead must ha ve the same dimensionalit y (2D or 3D) as the w orking case file . 3. Selec t the Imp orted S urfaces tha t will c onstr ain the b ounded sur faces. 3157Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the A djoin t Solver4. To visually c onfir m tha t the selec ted Bounded S urfaces and Imp orted S urfaces are appr opriate, click the Displa y butt on.The imp orted sur faces will b e color ed gr een b y default. Note When e xamining the sur faces, it ma y be helpful t o revise displa y pr operties of par tic- ular sur faces (f or e xample , the c olor , the le vel of tr anspar ency, and the visibilit y of the mesh edges or fac es).This c an b e done using the Scene D escr iption dialo g box, as descr ibed in Advanced Sc ene C omp osition (p.2848 ). Note tha t you c an e ven r evise the displa y pr operties of the imp orted sur faces, the names of which will b e displa yed with the pr efix bounding- . 5. When c onstr aining the Bounded S urfaces, you should ensur e tha t the y are constr ained on the correct side of the Imp orted S urfaces (tha t is, the side tha t has a p ositiv e or ientation) b y click ing the Orientation... butt on.The selec ted Imp orted S urfaces will b e displa yed, with their or ientation indic ated b y ar rows. In the dialo g box tha t op ens ( Figur e 44.17: The B ounding Or ientation D ialog Box (p.3158 )), you c an selec t individual Bounding S urfaces and Reverse their or ientation as ne- cessar y; you c an also incr ease the Skip value t o displa y fewer or ientation ar rows, for c ases wher e the ar row densit y obscur es the or ientation. Note tha t the or ientation y ou define f or a par ticular bounding sur face will b e used globally f or all bounded-b y-sur faces conditions . Figur e 44.17: The B ounding Or ientation D ialo g Box When r eviewing the or ientation of a b ounding sur face, you should v erify tha t the fac ets ha ve a unif orm or ientation, tha t is, all of the ar rows are on the same side of the sur face. Bounding sur faces with fac ets tha t ha ve a mix ed or ientation c an aff ect the c onvergenc e and/or accur acy of the calcula tion. 6. To pr escr ibe tha t the Bounded S urfaces def orms so as t o conform to the Imp orted S urfaces, enable the Fit to the imp orted sur faces? option. This is only r ecommended when the b ounded and imp orted sur faces ar e very similar in shap e and separ ated b y a small distanc e (on the or der of the lo cal cell dimensions). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3158Design A naly sis and Optimiza tion7. Click Apply in the Design C onditions tab of the Design Tool dialo g box to sa ve your settings . 8. If at an y point you w ould lik e to delet e an y of the Imp orted S urfaces, selec t them and click the Delet e butt on b elow the list. You c an also delet e them using the Surface M eshes D ialog Box (p.3929 ). Note When using the bounded-b y-sur faces condition, it is r ecommended tha t you apply pr e- conditioning on the ad vancemen t of the pr ocess f or up dating the fr eeform displac emen ts (by changing the Preconditioning field t o a p ositiv e value in the Numer ics tab of the Design Tool dialo g box, as descr ibed in Design Tool N umer ics (p.3162 )), in or der t o enc our- age the stabilit y of the solution. A v alue on the or der of 1 or 10 is r ecommended . Prescrib ed P rofiles You c an use the prescr ibed-pr ofile condition t o assign a motion pr ofile t o a w all z one or z ones using a DEFINE_GRID_MOTION UDF . 1. Selec t the w all z ones t o under go displac emen t in the Wall Z ones list. 2. Compile y our DEFINE_GRID_MO TION UDF in F luen t. (Refer to DEFINE_GRID_MOTION in the Fluent Customization Manual ). 3. Selec t your UDF in the Deformation pr ofile drop-do wn list. 4. Define the Scale F actor to be applied t o the def ormation pr ofile .You ha ve the f ollowing options: •Enter a set v alue . •Use the dr op-do wn menu t o define the sc ale fac tor thr ough an e xpression or input par amet er (f or example , as par t of a par ametr ic stud y managed b y Workbench); for details , see Directly A pplied Ex- pressions (p.665) or Creating a N ew P aramet er (p.845), respectively. •Disable the Prescr ibed option so tha t the sc ale fac tor is a fr ee par amet er.This c an b e helpful when you ar e trying t o optimiz e a design, because the D esign Tool will det ermine a sc ale fac tor tha t satisfies your goals , and so no input is r equir ed fr om y ou.The v alue will b e det ermined when y ou c alcula te the design change , and will b e pr inted in the c onsole; the pr inted v alue c an b e useful if y ou w ould like to recreate the design change in another sof tware pr ogram (r ather than e xporting it as an .stl file). 5. Click Apply . Rotation The rotation condition allo ws you t o sp ecify tha t sur faces under go r otation. 1. Selec t the sur faces (or clip-sur faces) y ou w ant to rotate in the Surfaces list. 2. Define the r otation Angle .You ha ve the f ollowing options: •Enter a set v alue in degr ees. 3159Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the A djoin t Solver•Use the dr op-do wn menu t o define the angle thr ough an e xpression or input par amet er (f or e xample , as par t of a par ametr ic stud y managed b y Workbench); for details , see Directly A pplied Expr es- sions (p.665) or Creating a N ew P aramet er (p.845), respectively. •Disable the Prescr ibed option so tha t the r otation is a fr ee par amet er.This c an b e helpful when y ou are trying t o optimiz e a design, because the D esign Tool will det ermine an angle tha t satisfies y our goals , and so no input is r equir ed fr om y ou.The v alue will b e det ermined when y ou c alcula te the design change , and will b e pr inted in the c onsole; the pr inted v alue c an b e useful if y ou w ould lik e to recreate the design change in another sof tware pr ogram (r ather than e xporting it as an .stl file). 3. Define the Origin about which y ou w ant the sur faces to rotate. Note tha t you c an click the Get Center butt on t o set the or igin fields t o the c oordina tes of the c enter of the selec ted sur faces. 4. For 3D c ases , define the Axis of r otation. For 2D c ases , this is aut oma tically defined as the p ositiv e Z axis. 5. Click Apply . Translation The transla tion condition allo ws you t o sp ecify tha t sur faces under go tr ansla tion. 1. Selec t the sur faces (or clip-sur faces) y ou w ant to transla te in the Surfaces list. 2. Define the Displac emen t for each c oordina te axis . For each field y ou ha ve the f ollowing options: •Enter a set v alue . •Use the dr op-do wn menu t o define the displac emen t thr ough an e xpression or input par amet er (f or example , as par t of a par ametr ic stud y managed b y Workbench); for details , see Directly A pplied Ex- pressions (p.665) or Creating a N ew P aramet er (p.845), respectively. •Disable the Prescr ibed option so tha t the tr ansla tion is a fr ee par amet er.This c an b e helpful when you ar e trying t o optimiz e a design, because the D esign Tool will det ermine a displac emen t tha t satisfies y our goals , and so no input is r equir ed fr om y ou.The v alue will b e det ermined when y ou calcula te the design change , and will b e pr inted in the c onsole; the pr inted v alue c an b e useful if y ou would lik e to recreate the design change in another sof tware pr ogram (r ather than e xporting it as an .stl file). 3. Click Apply . Scaling The scaling condition allo ws you t o sp ecify tha t sur faces ar e sc aled along one or mor e ax es. 1. Selec t the sur faces (or clip-sur faces) y ou w ant to sc ale in the Surfaces list. 2. Selec t the sc aling Type and define the asso ciated settings: •Radial This t ype sc ales the sur faces radially ab out the Origin , using a single sc aling Factor along each of the c oordina te ax es.The siz e of the sur faces will change , though not the shap e. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3160Design A naly sis and Optimiza tion•In-P lane This t ype is a vailable f or 3D c ases , and sc ales the sur faces ab out the Origin using a single scaling Factor along the t wo ax es of a plane (as defined b y the Normal D irection ). •Axial This t ype sc ales the sur faces ab out the Origin using a sc aling Factor along a single Axis. •Gener al This t ype sc ales the sur faces ab out the Origin using a separ ate sc aling Factor for each of the defined ax es. For 2D c ases , you define one Axis, and the sec ond axis is aut oma tically defined as b eing p erpendicular ; for 3D c ases , you define Axis 1 and Axis 2 (which should not b e par- allel), and the thir d axis is defined aut oma tically as the cr oss pr oduc t. Note tha t the sur faces will b e sc aled along each axis sequen tially , so the or der will b e relevant for non-or thogonal axes. For all t ypes, the sc aling Factor must b e positiv e. A v alue of 1 r esults in no change , while a v alue greater or less than 1 r esults in str etching or shr inking, respectively.You ha ve the f ollowing op- tions: •Enter a set v alue . •Use the dr op-do wn menu t o define the fac tor thr ough an e xpression or input par amet er (f or e xample , as par t of a par ametr ic stud y managed b y Workbench); for details , see Directly A pplied Expr es- sions (p.665) or Creating a N ew P aramet er (p.845), respectively. •Disable the Prescr ibed option so tha t the fac tor is a fr ee par amet er.This c an b e helpful when y ou are trying t o optimiz e a design, because the D esign Tool will det ermine a fac tor tha t satisfies y our goals , and so no input is r equir ed fr om y ou.The v alue will b e det ermined when y ou c alcula te the design change , and will b e pr inted in the c onsole; the pr inted v alue c an b e useful if y ou w ould lik e to recreate the design change in another sof tware pr ogram (r ather than e xporting it as an .stl file). When y ou ar e defining the Origin for an y of the t ypes, not e tha t you c an click the Get C enter butt on t o set the or igin fields t o the c oordina tes of the c enter of the selec ted sur faces. 3. Click Apply . Rigid B ody D eformation The rigid-b ody condition allo ws you t o sp ecify tha t sur faces under go r igid b ody motion, in which the r otations and tr ansla tions ar e free par amet ers.The D esign Tool will det ermine r otations and transla tions tha t satisfy y our goals when y ou c alcula te the design change , and will pr int them in the console .The pr inted v alues c an b e useful if y ou w ould lik e to recreate the design change in another software pr ogram (r ather than e xporting it as an .stl file); not e tha t you must apply the def ormations in the same or der as the y are pr inted t o obtain the same r esults . 1. Selec t the sur faces (or clip-sur faces) y ou w ant to under go r igid b ody motion in the Surfaces list. 2. Click Apply . 3161Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the A djoin t Solver44.2.5.6. Design Tool Numerics Smo othness As descr ibed in Smoothing and M esh M orphing (p.3118 ), ther e ar e two mor phing metho ds a vailable for the adjoin t solv er.The f ollowing descr ibes ho w smo othing is p erformed in each: •polynomials-based appr oach In this appr oach, the mesh mor phing is c ontrolled b y the summa tion of t wo smo othing bases: the Bernstein p olynomial basis which c ontrol the lar ge sc ale smo oth def ormation and the B-spline basis which c ontrols fine-sc ale def ormation. The choic e of smo othness det ermines the r elative weigh ting of these bases and ther efore the spa tial sc ale of the design change . A lar ge v alue of smo othness biases the design change t o one in which optimal displac emen ts vary in spac e in a manner domin- ated b y the B ernstein p olynomial basis .That is, the y ha ve a high degr ee of smo othness . A smaller value of smo othness leads t o a r ecommended design change with smaller spa tial sc ales . The abilit y to vary the smo othness par amet er is par ticular ly imp ortant when pr escr ibed f orms of deformation ar e applied . Deformation a t smaller spa tial sc ales r elieves the stiffness tha t would other wise c ause numer ical challenges as w ell as lead t o poor qualit y of the c omput ed design and mesh. •direct interpolation metho d In this metho d, the sur face mesh is smo othed using a Laplacian smo othing appr oach. Unlike the polynomials-based appr oach, the smo othness input do es not eff ect the c onvergenc e of the design conditions , but it has a str ong impac t of the smo othness of the displac emen t on the sur faces un- dergoing fr ee def ormation. This is an imp ortant par amet er in the dir ect interpolation metho d. By default , Fluen t will aut oma tically define the smo othness .You c an disable Auto-Selec t Smoothness in the Numer ics tab , and then a Smoothness input will b e available in the Design C hange tab .The default v alue of 1 f or Smoothness is suitable f or a v ariety of c ases; a reasonable r ange f or this field is between 10-3 and 103. Calculation Numerics Note If no Design C onditions are imp osed , and if ther e ar e no w alls tha t are treated as fix ed which in tersec t the r egion b eing mo dified , the numer ical settings descr ibed b elow ar e not used . In man y cases , no adjustmen t of the detailed numer ics will b e requir ed f or the D esign Tool to comput e an optimal solution. However, if the pr oblem under in vestiga tion in volves man y Design C onditions and/or lar ge displac emen ts, the settings ma y need t o be adjust ed. Note tha t all of these fields (e xcept for Max. Iterations in the Freeform M otions group b ox) ar e not needed when using the dir ect inter- polation metho d for mor phing , and ar e thus not a vailable f or editing . Prescr ibed M otions The following settings apply t o cases tha t involve the prescr ibed-pr ofile ,rotation ,scaling ,transla tion , and/or rigid-b ody design c onditions . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3162Design A naly sis and Optimiza tionMax. Iterations The maximum numb er of inner it erations tha t will b e performed in an eff ort to comput e displac emen ts from pr escr ibed changes . Constr aint Relaxa tion The under-r elaxa tion fac tor tha t is applied t o the field t o converge the pr escr ibed displac emen ts. This tak es a v alue b etween 0 and 1. Preconditioning A value of 0 yields the most aggr essiv e ad vancemen t, while a lar ger v alue enc ourages mor e stable , albeit slo wer, advancemen t of the pr ocess f or up dating the pr escr ibed displac emen ts. A value of order 1 is t ypic al in the e vent tha t preconditioning needs t o be applied . Freeform M otions Max. Iterations The maximum numb er of inner it erations tha t will b e performed in an eff ort to comput e freeform displac emen ts tha t satisfy the applied Design C onditions . Constr aint Relaxa tion The under-r elaxa tion fac tor tha t is applied t o the field t o converge the c onstr ained fr eeform displac e- men ts.This tak es a v alue b etween 0 and 1. Preconditioning A value of 0 means tha t no pr econditioning is applied , while a lar ger v alue enc ourages mor e stable , albeit slo wer, advancemen t of the pr ocess f or up dating the fr eeform displac emen ts. A value of or der 1 is t ypic al in the e vent tha t preconditioning needs t o be applied . Paramet er Relaxa tion For c ases tha t include a rigid-b ody condition and/or a design c ondition with a fr ee par amet er (for e xample , the rotation condition with Prescr ibed option disabled f or the Angle ), ther e are additional par amet ers tha t are implicit in the c alcula tion. The v alues of these par amet ers are comput ed as par t of the solution pr ocess.The v alue of the par amet er relaxa tion defines the r ate at which these par amet ers ar e corrected as the c alcula tion pr ogresses .This tak es a value b etween 0 and 1. Toler anc es Constr aints The t oler ance for convergenc e of the r esiduals asso ciated with the design c onditions themselv es, or fix ed z one c onditions . Paramet ers The t oler ance for convergenc e of the par amet ers asso ciated with the design c onditions . Using a v alue of 1 f or Constr aint Relaxa tion and a v alue of 0 f or Preconditiong yields the most aggr essiv e behavior.This c an r esult in the f ewest numb er of it erations t o converge a c onstr ained problem, at the e xpense of some added numer ical eff ort and memor y in pr epar ing the pr econditioning . For 2D and small 3D pr oblems the added c ost in time and memor y is t ypic ally small. For lar ger problems in volving multiple c onstr aints a non-z ero Preconditioning and Constr aint Relaxa tion less than 1 ma y be pr eferable .The e xecution time t o set up the pr econditioning will b e less , as will the memor y usage . Calcula tion stabilit y can also b e impr oved.The numb er of it erations r equir ed t o con- 3163Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the A djoin t Solververge the pr oblem will incr ease . However, this c an pr ove to be an eff ective str ategy tha t results in an o verall shor ter time needed t o comput e the design change . 44.2.5.7. Shap e Mo dific ation The pr ocedur e for c omputing the optimal design change and def orming the mesh is as f ollows: 1. Click the Design C hange tab . 2. Selec t those b oundar ies tha t are free t o be par tially c onstr ained or def ormed in the Zones To Be M odified field . Boundar ies tha t are not selec ted in this b ox tha t intersec t the c ontrol volume will b e constr ained not t o mo ve.This is useful if ther e ar e walls tha t, for design r easons , must remain fix ed and not mo ve. Note •If you ha ve a t wo-sided w all tha t you w ant to def orm, it is r ecommended tha t you selec t both the w all and the c orresponding w all-shado w. •When using the Direct Interpolation mor phing metho d, you must ensur e tha t none of the z ones in volved in a non-c onformal mesh in terface are selec ted. 3. Selec t the c onstr aining and/or def ormation c onditions ( Defining C onditions f or the D eforma- tion (p.3155 )) to be applied t o the design change in the list of Applied C onditions . Note tha t a given sur face cannot ha ve multiple c onditions of t ype prescr ibed-pr ofile ,rotation ,transla tion , scaling , or rigid-b ody. You c an click the Displa y butt on under the Applied C onditions list, in or der t o displa y the applied conditions in the gr aphics windo w, each t ype in a unique c olor . Note tha t this includes the conditions selec ted in the list , as w ell as the fix ed c onditions applied t o zones tha t are not selec ted in the Zones To Be M odified list. This mak es it easy t o review y our setup , and iden tify an y overlapping c onditions (r ecognizable b y their t wo-tone c ells). 4. When using the Polynomials mor phing metho d, by default the c ondition or c onditions sp ecified for a giv en z one (including the selec ted Applied C onditions , as w ell as the fix ed c ondition applied to the unselec ted Zones To Be M odified ) are not applied t o every no de, but inst ead t o a subset of no des distr ibut ed thr oughout the z one; this is t o avoid o verly constr aining the z one . Con- sequen tly, some no des will not str ictly adher e to the c ondition, even if y ou ha ve defined the constr aint toler ance to be small or the r esiduals ar e small. To sp ecify tha t all no des of the z one strictly ob ey the c ondition, click the Strict Conditions ... butt on under the Applied C onditions selec tion list and use the dialo g box tha t op ens ( Figur e 44.18: The S trict Conditions D ialog Box (p.3165 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3164Design A naly sis and Optimiza tionFigur e 44.18: The S trict Conditions D ialo g Box Selec t the c onditions f or which y ou w ant str ict enf orcemen t and click OK. For unselec ted c ondi- tions , only the default subset of no des will str ictly ob ey the c ondition. Note tha t when y ou apply strict enf orcemen t to a c ase in which the Objec tive is Target C hange in Value (as descr ibed in Defining O bser vable O bjec tives (p.3154 )), the desir ed change in the v alue ma y not b e achie ved. Note Strict enf orcemen t is a dir ect mo dific ation of the sur face mesh no des t o sa tisfy the design c ondition, and no mo dific ation is applied on the in terior mesh. Consequen tly, when the b oundar y no de mo dific ation is lar ge, it ma y det eriorate the mesh or e ven cause nega tive volumes .Therefore you should use this c ondition c arefully : the design condition should r each a go od convergenc e and ther e should b e enough c ontrol points. When y ou click the Modify butt on (as descr ibed in a la ter st ep), the maximum off set f or each condition (tha t is, the maximum distanc e a no de has de viated fr om the pr escr ibed c ondition) will b e pr inted t o the c onsole . 5. For each obser vable , specify its Weigh t in the optimiza tion c alcula tion. The w eigh ts ar e applied t o the Target/Ref erenc e Change you sp ecified in the Objec tives tab .That is, if you ha ve two obser vables that are each giv en a Weigh t equal t o 1, Fluen t will a ttempt t o find an optimal design change tha t alt ers the obser vable v alues in pr oportion t o their r espective values f or Target/Ref erenc e Change . Note Weigh ts ar e only r equir ed if ther e ar e two or mor e objec tives tha t do not ha ve explicit target changes sp ecified . 6. Specify the def ormation par amet ers. 3165Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the A djoin t Solvera. When using the Polynomials mor phing metho d, cho ose a Freeform Sc aling Scheme and specify the Freeform Sc aling F actor.This setting c ontrols ho w the o verall sc aling fac tor for the design change magnitude is in terpreted. Control-P oint Spacing The magnitude of the fr eeform def ormation will b e based on the c ontrol-p oint spacing . That is, a Freeform Sc ale F actor of 1.0 leads a t o maximum c ontrol p oint mo vemen t on the or der of one sub-c ell of the c ontrol volume .The sub-c ell siz e is det ermined b y a unif orm sub-division of the mor phed r egion based on the numb er of c ontrol p oints sp ecified (Defining R egion C onditions (p.3153 )). A value of 1.0 is a r easonable default t o pr eser ve mesh qualit y dur ing the mor phing pr ocess. Objec tive Ref erenc e Change The magnitude of the fr eeform def ormation will b e based on the Target/Ref erenc e Change value in the Objec tives tab .That is, for a single obser vable optimiza tion with Freeform Sc ale F actor of 1.0 , the design change c omput ed will yield an e xpected change in the obser vable equal t o the Target/Ref erenc e Change for the obser vable . b.If you ha ve disabled Auto-Selec t Smoothness in the Numer ics tab , you c an also sp ecify a v alue for Smoothness of the def ormed geometr y. A lo wer value will allo w lo cally shar per changes in the geometr y, potentially a t the e xpense of manufac turabilit y. For details ab out this setting , see Design Tool N umer ics (p.3162 ). c.If you used an input par amet er as par t of the setup of a def ormation c ondition in the Design Conditions tab , the initial v alue will b e displa yed and is a vailable f or mo dific ation. 7. Click the Check butt on t o verify tha t your c onstr aining and/or def ormation c onditions ar e set up in such a w ay as t o pr oduce go od results . A report will b e pr inted in the c onsole listing c onflic ts between multiple c onstr aints / def ormations applied on a single no de (including the Design C onditions and the c ontinuit y constr aint applied along the b oundar y of the mor phing r egion). The c onflic ts ar e categor- ized as b eing either of t ype Fatal (which indic ates the solution is unlik ely t o converge or b e desir able) or Possible (which ma y be allo wable , dep ending on the details of the applied c onditions). 8. Click Calcula te Design C hange to comput e the optimal design change .The Expected change for each obser vable will b e reported in the Design Tool dialo g box. 9. (optional) You c an e xport the e xpected changes or displac emen ts b y click ing the Export... butt on and click ing the f ollowing butt ons in the Design E xport dialo g box tha t op ens: •Click Export Expected C hange ... to wr ite to file the adjustmen t in the obser vable tha t is e xpected due t o the change defined b y the cur rent settings . •Click Export Displac emen ts... to wr ite to file the optimal sur face displac emen t field (o verwriting any pr e-existing file of the same name). An example of the f ormat of the t ext file tha t is wr itten (f or three-dimensions) is as f ollows: Line 1: n Lines 2 to n+1: x y z dx dy dz Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3166Design A naly sis and Optimiza tionFigur e 44.19: The D esign E xport Dialo g Box 10. The planned change t o the geometr y can b e displa yed in the gr aphics windo w b y click ing the Preview... butt on and then using the Preview M orphing dialo g box tha t op ens t o displa y the surfaces of in terest. Note tha t you c an use the butt ons t o easily selec t all the Outline boundar ies and/or the Interior sur faces, and y ou c an incr ease the Scale to acc entuate the mor phing pr eview or e xported .stl .When y ou click the Displa y butt on, the selec ted sur faces ar e displa yed unde- formed in whit e and def ormed in gr een. Figur e 44.20: The P review M orphing D ialo g Box Note tha t for 3D c ases y ou c an also use the Export STL... butt on t o export the pr eview ed mesh as an .stl file.This is useful f or lar ge c ases , as it means y ou do not ha ve to ac tually mor ph the mesh in or der t o ha ve the pr eview ed geometr y available f or use in other sof tware pack ages . 11. Click the Modify butt on in the Mesh group b ox to def orm the b oundar y and in terior mesh with the optimal design change .You should then e xamine the mo dified shap e and mesh t o det ermine if the r esults ar e sa tisfac tory, using the usual c ommands f or viewing the mesh in ANSY S Fluen t. When using the Direct In terpolation mor phing metho d, it is r ecommended tha t you check the resulting mesh qualit y and v erify tha t no b oundar y zones cr oss / p enetr ate themselv es or other 3167Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the A djoin t Solverboundar y zones . If you det ermine tha t the change is unsa tisfac tory, you c an click Revert to undo the mesh changes . After the mesh has b een mo dified acc ording t o the c ontrol settings , the or iginal flo w calcula tion c an be restar ted and c onverged with the mo dified geometr y. Upon succ essful c onvergenc e, the obser vable value should no w ha ve changed b y an amoun t similar t o tha t reported when the Export Expected Change ... butt on w as click ed pr ior t o def orming the geometr y. For 3D c ases , you ha ve the option of e xporting the sur faces fr om y our mo dified geometr y as an .stl file, for use in other sof tware pack ages . Click the Export... butt on near the b ottom of the Design Change tab and then click the Export STL... butt on in the Export dialo g box tha t op ens. Finally , selec t the Surfaces of in terest in the dialo g box tha t op ens ( Figur e 44.21: The Exp ort STL D ialog Box (p.3168 )) and Export... them. Figur e 44.21: The E xport STL D ialo g Box 44.2.6. Using the G radien t-Based Optimiz er The adjoin t solv er pr ovides an Gradien t-Based Optimiz er tha t can aut oma tically cr eate a ser ies of it- erations of a design, so tha t the mesh gr adually def orms t o an optimal shap e in or der t o meet multiple objec tives a t multiple op erating c onditions .To pr epar e to use the Gradien t-Based Optimiz er, you will p erform most of the usual st eps outlined in Using the A djoin t Solver (p.3120 ) (including the setup of the Design Tool), with the f ollowing e xceptions: •It is not nec essar y to star t with a c onverged flo w solution; simply initializing the c ase file is sufficien t. •It is not nec essar y to selec t a single obser vable in the Adjoin t Obser vables dialo g box, as y ou will b e able to selec t multiple obser vables in a separ ate dialo g box. •It is not nec essar y to initializ e the adjoin t solution and it erate to convergenc e using the Run A djoin t Cal- cula tion dialo g box, as these ac tions will b e performed in the Gradien t-Based Optimiz er dialo g box. •When setting up the Design Tool: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3168Design A naly sis and Optimiza tion–It is not nec essar y to export / imp ort sensitivit y da ta, as this will b e handled aut oma tically dur ing optim- ization. –It is not nec essar y to sp ecify the objec tives for the obser vables in the Objec tives tab of the Design Tool dialo g box, as this will b e done in the Gradien t-Based Optimiz er dialo g box. –In the Design C hange tab of the Design Tool dialo g box, it is not nec essar y to tak e an y ac tion in the Workflo w,Mesh, and Results group b oxes. Note tha t while the ab ove steps ar e not nec essar y, you ma y yet w ant to perform them in or der t o verify tha t your settings ar e pr operly defined (f or e xample , to ensur e your design c onditions ar e not conflic ting) pr ior t o using the optimiz er. To star t, you must define the settings f or the flo w solution and initializ e it; if y ou w ant to optimiz e the design f or multiple op erating c onditions , as par t of this st ep y ou should cr eate input par amet ers f or the c ell z one and b oundar y condition settings y ou w ould lik e to vary. Next, you must define the adjoin t obser vables , metho ds, solv er controls, monit ors, and Design Tool, noting the e xceptions list ed pr evi- ously .Then y ou c an op en the Gradien t-Based Optimiz er dialo g box by click ing Gradien t-Based Optimiz er... in the Design ribbon tab ( Adjoin t-Based group b ox). Design → Adjoin t-Based → Gradien t-Based Optimiz er... 3169Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the A djoin t SolverFigur e 44.22: Gradien t-Based Optimiz er D ialo g Box The gener al pr ocedur e to use the Gradien t-Based Optimiz er is as f ollows: 1. Click the Obser vables ... butt on t o op en the Adjoin t Optimiz er O bser vables dialo g box, wher e you can selec t all of the r elevant obser vables f or y our optimiza tion pr oblem and click OK. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3170Design A naly sis and Optimiza tionFigur e 44.23: Adjoin t Optimiz er O bser vables D ialo g Box 2. Click the Conditions ... butt on t o op en the Adjoin t Optimiz er C onditions dialo g box. Figur e 44.24: Adjoin t Optimiz er C onditions D ialo g Box Define the f ollowing: Numb er of Op erating C onditions This defines the numb er of p ossible op erating c onditions . Each op erating c ondition is a set of simu- lation pr operties f or which a flo w solution will b e calcula ted. As you incr ease this numb er, mor e rows will b e added t o the gr oup b ox below, each with a unique No..The Active? option must b e enabled to calcula te the flo w for tha t op erating c ondition. Numb er of Input P aramet ers This defines the numb er of input par amet ers y ou w ould lik e to define f or each op erating c ondition. As you incr ease this numb er, mor e columns will b e added t o the gr oup b ox below.You c an selec t an input par amet er fr om one of the t op dr op-do wn lists , and then define its v alue f or each op erating condition in the numb er-en try boxes b elow it. When y ou ha ve defined all the op erating c onditions , click Apply , and close the Adjoin t Optimiz er Conditions dialo g box. 3171Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the A djoin t Solver3. Fill out the f ollowing c olumns f or the table in the Objec tives group b ox. Each r ow represen ts a unique combina tion of the ac tive op erating c onditions and the selec ted obser vables defined in the pr evious steps. Goal This det ermines ho w Fluen t will a ttempt t o change the v alue of the obser vable thr ough the design change .You c an sp ecify a Target change in v alue; other wise y ou c an selec t None , in which c ase the obser vable will not b e consider ed in c omputing the optimal design change , and the pr edic ted change in obser vable v alue will not b e reported. Value When the Goal is a Target change in the obser vable , this field c orresponds t o the desir ed change in the v alue . Percentage? Enabling this option sp ecifies tha t the Value is a p ercentage of the v alue of the obser vable . A tar get change of 5–10% is t ypic ally a go od star ting p oint, dep ending on the pr oblem. 4. The Adaptiv e Value option is enabled b y default , and is gener ally r ecommended .When using this option, Fluen t aut oma tically det ects when a design it eration pr oduces non-optimal r esults (c ompar ed t o pr evious flow solutions), and r eattempts the design using Objec tives settings tha t are less aggr essiv e.The pr ocess is as f ollows: the solution c alcula ted f or the initial design is c onsider ed optimal and wr itten t o disk; then the f ollowing t wo steps ar e repeated. 1.The design is r evised based on the cur rent Objec tives settings . 2.The flo w solution is c alcula ted, and the r esults ar e compar ed t o the optimal design solution: •If the v alues of all of the obser vables f or all of the op erating c onditions impr ove or r emain the same , the r evised design solution is deemed the new optimal (and the files ar e overwritten), and the pr ocess r etur ns to step 1. •If the v alue of one or mor e of the obser vables f or an y of the op erating c onditions w orsens , the optimal design solution is r estored, the Objec tives settings ar e revised such tha t every Value is reduc ed b y 50% going f orward, a new design is gener ated, and the pr ocess r etur ns to step 2. When using the Adaptiv e Value option, not e the f ollowing: •The naming c onvention f or the optimal design solution files is pr ovided in a la ter st ep tha t descr ibes how to set up aut osaving . •You must ensur e tha t you ha ve sufficien t disk spac e for the optimal design solution files . •You must not r emo ve or r ename the optimal design solution files dur ing optimiza tion. •You must ensur e tha t the optimal design solution files ar e in the c orrect folder if y ou st op the optim- ization and then c ontinue it. •If a pr oblem o ccurs dur ing optimiza tion, you c an either : –initializ e the optimiz er again: the cur rent design solution files will b e sa ved as the optimal if optim- ization c ontinues , and the Curr. Design I teration will b e reset t o 0 and the optimiza tion hist ory in the monit or plot will b e lost. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3172Design A naly sis and Optimiza tion–reset it: the cur rent design solution files will b e sa ved as the optimal if optimiza tion c ontinues , but the Curr. Design I teration will not b e reset t o 0 and the optimiza tion hist ory in the monit or plot will not b e lost. •If you st op the optimiz er, mo dify some settings , and then c ontinue the c alcula tion, not e tha t your changed settings ma y be overwritten if the optimal design solution is r estored dur ing the first it eration. 5. The Optimiz er S ettings group b ox allo ws you t o view / set the f ollowing: Curr. Design I teration This displa ys the cur rent design it eration. No. of D esign I terations This sp ecifies the maximum numb er of design it erations tha t the optimiz er will p erform. A value in the r ange of 10–20 is t ypic ally appr opriate, dep ending on the pr oblem and settings . Convergenc e Criteria This defines the cr iteria by which the design is c onsider ed c onverged . For e very obser vable a t every operating c ondition, the f ollowing ar e calcula ted dur ing v arious p oints in the design it eration: •the e xpected change / initial v alue (when the design change is c alcula ted) •the ac tual change / initial v alue (when the flo w solution is c alcula ted) When either of the ab ove ar e less than y our sp ecified Convergenc e Criteria for all obser vables at all op erating c onditions , the optimiz er will st op it erating . No. of F low Iterations This sp ecifies the maximum numb er of it erations p erformed dur ing the c alcula tion of the flo w solution. A star ting v alue of 300 is t ypic ally appr opriate, dep ending on the pr oblem and settings . No. of A djoin t Iterations This sp ecifies the maximum numb er of it erations p erformed dur ing the adjoin t calcula tion. A star ting value of 500 is t ypic ally appr opriate, dep ending on the pr oblem and settings . 6. Specify the settings in the Mesh Q ualit y group b ox. By default , the c ell v olume and or thogonal qualit y (as defined in Mesh Q ualit y (p.719)) is c omput ed at the star t of e very design it eration, before the flo w solution is c alcula ted; if the mesh viola tes your sp ecified Min. Cell Volume and/or Min. Ortho gonal Q ualit y, the optimiz er st ops. Such a check is also p erformed immedia tely af ter each design change is c alcula ted; if this check fails , Fluen t reattempts the design using Objec tives settings tha t are less aggr essiv e, in the same manner as descr ibed pr eviously f or the Adapt ed Value option (r egar dless of whether tha t option is enabled). This helps t o ensur e tha t your solution accur acy is not c ompr omised b y poor qualit y meshes .When the dir ect interpolation metho d is used , the mesh qualit y ma y det eriorate quick ly at local regions , ther efore the v alue will b e reduc ed quick ly.You ma y continue the optimiza tion by readjusting the v alue , acc ordingly .When setting these minimums , you c an click the Print Current Status butt on and en ter v alues tha t are sufficien tly lo wer then those pr inted in the console , so as not t o rejec t a major ity of the meshes gener ated dur ing the optimiza tion pr ocess. Note tha t it is r ecommended tha t you set the Min. Ortho gonal Q ualit y to a v alue gr eater than 0, in or der t o avoid lef t-handed fac es. 3173Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the A djoin t SolverThe Impr ove M esh Q ualit y After M orphing option is enabled b y default. This a ttempts t o repair the mesh a t the end of the design it eration (af ter the mesh has mor phed) b y applying the f ollowing text command 3 times: mesh/repair-improve/improve-quality . Note tha t this t ext command ma y det eriorate the mesh in c ertain cir cumstanc es. 7. You c an set up a monit or of the optimiza tion hist ory by click ing the Monit or.... butt on in the Calcula tion Activities group b ox. Figur e 44.25: Adjoin t Optimiza tion Hist ory M onit or D ialo g Box The Adjoin t Optimiza tion Hist ory M onit or dialo g box has the f ollowing c ontrols: Plot D uring the Optimiza tion This option sp ecifies whether plotting is p erformed f or each design it eration. Obser vable Values This option enables the plotting of obser vable v alues fr om the flo w calcula tion. The da ta is r epresen ted by solid lines . Expected O bser vable Values This option enables the plotting of e xpected obser vable v alues f or the ne xt design it eration. It is calcula ted b y tak ing the cur rent obser vable v alue and adding the e xpected change due t o the mesh mor phing in the cur rent design it eration. The da ta is r epresen ted b y dashed lines . If dashed and solid lines of the same c olor do not ma tch w ell, tha t is a sign tha t the sensitivit y is not accur ate for that obser vable , and so y ou ma y need r evise y our setup (impr ove the c onvergenc e of the flo w and/or adjoin t solv ers, reduc e optimiza tion v alues , and so on). Plot A ll Optimiza tion IDs This option enables the plotting of da ta for all optimiza tion IDs , tha t is, all of the r ows of the table in the Objec tives group b ox; other wise , only a single optimiza tion ID will b e plott ed. Optimiza tion ID t o be Plott ed This field sp ecifies the individual optimiza tion ID t o be plott ed, and is only a vailable when the Plot All Optimiza tion IDs option is disabled .The numb er you en ter corresponds t o the ID in the Objec t- ives group b ox. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3174Design A naly sis and Optimiza tionWindo w This field sets the ID of the gr aphics windo w in which the plot is displa yed. 8. You c an set up the aut oma tic sa ving of files dur ing optimiza tion b y click ing the Autosa ve.... butt on in the Calcula tion A ctivities group b ox. Note tha t the r esulting c ase and da ta files will use the Hier archic al Data Format (HDF) if without an y post-fix, such as .cas ,.dat ,.cas.gz , etc. All of the files will b e saved af ter the adjoin t design c alcula tion but b efore the mor phing of the mesh. Figur e 44.26: Adjoin t Optimiz er A utosa ve D ialo g Box The Adjoin t Optimiz er A utosa ve dialo g box has the f ollowing c ontrols: File N ame This field sp ecifies the r oot name f or the files tha t are sa ved. It is suggest ed tha t you do not include an e xtension f or the file name . If you include a f older , you must mak e sur e tha t it is acc essible . Save Case and D ata F iles (E very Design I teration) This gr oup b ox allo ws you t o sp ecify settings f or the aut osaving of c ase and da ta files .Every (D esigns) sets the fr equenc y, in design it erations .The Max. Files Retained sets the limit af ter which the ear liest existing files ar e overwritten b y the la test. The files ar e sa ved with the f ollowing names: •-design- .cas.h5 •-design- .dat.h5 •-id- .sens (only when y ou ha ve defined multiple op erating conditions and/or objec tives) wher e is the File N ame , is a thr ee-digit numb er corresponding t o the design it eration, and is a t wo-digit numb er corresponding t o the ID in the Objec tives group b ox. 3175Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the A djoin t SolverSave Optimal C ase and D ata F iles This gr oup b ox pr ovides the Save During the Optimiza tion option; when enabled , a single set of optimal design solution files is sa ved and r ewritten as nec essar y (as descr ibed pr eviously in the st ep descr ibing the Adaptiv e Value option). The files ar e sa ved with the f ollowing names: •-design-optimal.cas.h5 •-design-optimal.dat.h5 •-id- -optimal.sens (only when y ou ha ve defined multiple operating c onditions and/or objec tives) wher e is the File N ame and is a t wo-digit numb er corres- ponding t o the ID in the Objec tives group b ox. If you mo ve the .cas /.dat files t o a diff erent location, mak e sur e to mo ve the optimal .cas /.dat and .sens files (only when y ou ha ve defined multiple op erating c onditions and/or objec tives) along with it , and set up the pr oper File N ame for the new lo cation in or der to continue the optimiza tion. The optimal files ar e needed t o restore the optimiza tion. Other- wise , you c an r eset the optimiz er and c ontinue the optimiza tion. Note tha t the Save D uring the Optimiza tion option c an only b e disabled if y ou ha ve disabled the Adaptiv e Value option. Export STL F iles (E very Design I teration) This gr oup b ox allo ws you t o set up the aut oma tic e xporting of .stl files (f or 3D c ases only), for use in other sof tware pack ages .Every (D esigns) sets the fr equenc y, in design it erations .The Export STL S etting ... butt on op ens the Export STL dialo g box, wher e you c an selec t the Surfaces of in terest. The files ar e sa ved as -design- .stl , wher e is the File N ame and is a thr ee-digit numb er corresponding t o the design it eration. 9. You c an set up c ommands t o be execut ed dur ing optimiza tion (such as p ostpr ocessing c ommands tha t export fields) b y click ing the Execut e Commands ... butt on in the Calcula tion A ctivities group b ox and using the Execut e Commands D ialog Box (p.3637 ) tha t op ens. For details , see Executing C ommands D uring the C alcula tion (p.2660 ). Note tha t onc e you ha ve op ened this dialo g box from Gradien t-Based Optimiz er dialo g box, the f ollowing selec tions b ecome a vailable in the When drop-do wn list: Design I teration This sp ecifies tha t execution of the c ommand is based on the design it eration. It is e xecut ed af ter the design c alcula tion and b efore an y anima tion r ecording , both of which ar e before the mor phing of the mesh. Adjoin t Iteration This sp ecifies tha t execution of the c ommand is based on the adjoin t iteration. It is e xecut ed imme- diately b efore each adjoin t ad vancemen t step. Note tha t une xpected b ehavior ma y result if the e xecut ed c ommand changes settings f or the adjoin t calcula tion and/or gr adien t-based optimiz er. 10. You c an set up anima tions t o be recorded dur ing optimiza tion b y click ing the Solution A nima tion... butt on in the Calcula tion A ctivities group b ox and using the Anima tion D efinition D ialog Box (p.3781 ) that op ens. For details , see Creating an A nima tion D efinition (p.2670 ). Note tha t onc e you ha ve op ened Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3176Design A naly sis and Optimiza tionthis dialo g box from Gradien t-Based Optimiz er dialo g box, the f ollowing selec tion b ecomes a vailable in the dr op-do wn list ne xt to the Rec ord af ter e very field: design-it eration This sp ecifies tha t the r ecording is based on the design it eration. It is r ecorded af ter the design c al- cula tion and the e xecution of an y commands , and b efore the mor phing of the mesh. For details on pla ying , saving , and/or r eading the r esulting anima tion, see Anima ting the S olu- tion (p.2670 ). 11. Click the Initializ e butt on in the Calcula tion group b ox of the Gradien t-Based Optimiz er dialo g box, and then click the Optimiz e butt on t o star t the design it erations .The optimiz er will pr oceed un til one of the f ollowing c onditions is met: •the Convergenc e Criteria is met f or all of the obser vables •the No. of D esign I terations is reached f or this optimiz er run •the mesh qualit y requir emen ts cannot b e met •you in terrupt the c alcula tion •an er ror o ccurs If you w ant to continue t o optimiz e the design with r evised settings f or the obser vables , operating conditions , objec tives, and/or the Adapt ed Value option, it is r ecommended tha t you either Ini- tializ e the optimiz er again or Reset it: the cur rent design solution files will b e sa ved as the optimal if optimiza tion c ontinues , and (f or Initializ e) the Curr. Design I teration will b e reset t o 0 and the optimiza tion hist ory in the monit or plot will b e lost. When the optimiza tion is c omplet e, you c an click the Summar ize butt on t o pr int a r eport of the results f or each design it eration in the c onsole , including the obser vable v alues , the e xpected changes , whether the flo w and adjoin t calcula tions c onverged , and the mesh qualit y metr ics. When using the Gradien t-Based Optimiz er, not e the f ollowing: •It is a go od pr actice to initially r un the optimiz er for one design it eration, in or der t o check if the settings are pr oper. •The r esulting design will b e highly aff ected b y whether or not the flo w solv er and/or adjoin t solv er reach convergenc e. Auto-adjust c ontrols and blend stabiliza tion str ategies ar e recommended f or convergenc e of the adjoin t solv er. •You ma y want to perform a first r ound of optimiza tion using lo wer accur acy settings , and then swit ch to higher accur acy settings as y ou appr oach the optimal solution. For the first r ound y ou c ould c onsider using the f ollowing: –settings (f or e xample , in the Solution M etho d task page) tha t help flo w convergenc e and/or r educ e the residual oscilla tion –a coarser mesh •If you change the settings dur ing the optimiza tion (which c an change an obser vable v alue), you should mak e sur e to initializ e or r eset , so tha t the optimiz er considers the cur rent solution t o be optimal and star ts the optimiza tion fr om the cur rent solution; other wise , the changed obser vable v alue ma y be worse than 3177Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the A djoin t Solverin pr evious c alcula tions , and if the Adaptiv e Value option is enabled , Fluen t will r estore the sa ved optimal solution and c ontinue , which will undo y our settings changes . 44.3. The M esh M orpher/Optimiz er The mesh mor pher/optimiz er off ers a v ariety of non-gr adien t-based optimiza tion algor ithms t o optimiz e the geometr ic shap e of a sy stem [53] (p.4007 ).The optimiza tion c an b e performed f or a wide v ariety of physics and quan tities of in terest t o be optimiz ed. For additional inf ormation, see the f ollowing sec tions: 44.3.1. Limita tions 44.3.2. The Optimiza tion P rocess 44.3.3. Optimiz ers 44.3.1. Limita tions Note the f ollowing limita tions of the ANSY S Fluen t mesh mor pher/optimiz er: •The mesh mor pher/optimiz er should not b e used with d ynamic or sliding mesh pr oblems . •Any geometr ically e valua ted par amet ers r equir ed f or flo w it erations (f or e xample , view fac tors f or the sur face to sur face (S2S) r adia tion mo del) will need t o be recomput ed a t the v ery least when the optimiza tion is c omplet e. If the objec tive func tion is aff ected b y one of these geometr ically e valua ted paramet ers, then such par amet ers will need t o be recomput ed af ter each design change; for e xample , the view fac tors need t o be recomput ed af ter each design change when the objec tive func tion is a func tion of t emp erature. •Arbitr arily shap ed def ormation r egions ar e not supp orted. 44.3.2. The Optimiza tion P rocess All optimiza tion pr oblems r equir e tha t you iden tify par amet ers tha t can b e mo dified in or der t o reach the optimiz ed solution. In the c ase of the mesh mor pher/optimiz er, it is the geometr y tha t must b e paramet erized. Geometr ic par amet erization f or gener al shap es used in CFD c an b e very complic ated, due t o the lar ge v ariety of shap es a vailable in engineer ing applic ations . In or der t o minimiz e such complic ations in y our ANSY S Fluen t simula tion, the pr oblem of shap e par amet erization is r educ ed t o a pr oblem of the par amet erization of changes in the geometr y. The ne xt essen tial r equir emen t for mesh mor phing is a t ool tha t can smo othly alt er the shap e, irre- spective of the under lying mesh t opology. In ANSY S Fluen t, designa ted def ormation r egions ar e ma- nipula ted via displac emen ts applied t o a set of c ontrol p oints.The mesh r egion tha t is t o be def ormed is defined b y a “box” (tha t is, a rectangle f or 2D c ases and a r ectangular he xahedr on f or 3D), and the control p oints must b e lo cated within the b ox.The displac emen ts of the c ontrol p oints ar e the r esult of user-defined motions (each of which in volves a par amet er v alue and other dir ectional settings) and these displac emen ts ar e then applied t o the mesh as a smo oth def ormation b y either in terpolating the displac emen t based on r adial basis func tions or using the t ensor pr oduc t of B ernstein p olynomials . The ne xt requir emen t is t o ha ve an optimiz er tha t is r obust enough t o handle a wide r ange of pr oblems . By coupling such optimiz ers with y our CFD analy sis, you c an gr eatly impr ove your design with minimal intervention. You c an use built-in optimiz ers t o vary the par amet er v alues along the pr escr ibed dir ections and within defined b ounds , in or der t o sa tisfy a c ondition sp ecified b y an objec tive func tion. The mesh mor pher/optimiz er pr ovides y ou with acc ess t o six optimiz ers tha t are not based on gr adien ts. Other wise , Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3178Design A naly sis and Optimiza tionyou c an manually sp ecify the def ormation (tha t is, define b oth the par amet er v alues and the dir ections) and analyz e the r esults; you also ha ve the option of using D esign Explor ation in ANSY S Workbench t o easily e xplor e the impac t of a v ariety of par amet er v alues . 44.3.3. Optimiz ers The built-in optimiz ers used as par t of the mesh mor pher/optimiz er capabilit y in ANSY S Fluen t use direct sear ch metho ds for optimiza tion. Direct sear ch metho ds ar e zeroth or der, as the y only use the objec tive func tion v alues f or optimiza tion. The dir ect sear ch metho ds do not use the der ivatives. The f ollowing is a list of ad vantages of dir ect sear ch metho ds: •Direct sear ch metho ds do not r equir e der ivatives for optimiza tion. •Direct sear ch metho ds ar e robust f or pr oblems with disc ontinuities and in situa tions wher e the der iv- ative computa tion is not p ossible or unr eliable . The f ollowing is a list of disad vantages of dir ect sear ch metho ds: •Convergenc e pr oof is not clear ly defined . •The r ate of c onvergenc e can b e very slo w. Gener al explana tions of the six diff erent built-in optimiz ers ar e pr ovided in the f ollowing sec tions: 44.3.3.1. The C ompass Optimiz er 44.3.3.2. The NE WUO A Optimiz er 44.3.3.3. The S imple x Optimiz er 44.3.3.4. The Torczon Optimiz er 44.3.3.5. The P owell Optimiz er 44.3.3.6. The R osenbr ock Optimiz er 44.3.3.1. The C ompass O ptimiz er In the C ompass optimiz er [60] (p.4008 ), the par amet ers ar e adjust ed one b y one un til the objec tive func tion is minimiz ed.This optimiz er star ts with a giv en v alue and then e valua tes the func tion v alue in all the basic dir ections .The dir ection her e refers t o the p ositiv e and nega tive incr emen ts to the initial par amet er v alues . If ther e is a r educ tion in the func tion v alue , then tha t point becomes an im- proved p oint. If ther e is no impr ovemen t in the func tion v alues , then the st ep length is r educ ed b y half and the sear ch is r epeated in all dir ections .The algor ithm t ermina tes when the st ep siz e falls below a c ertain t oler ance. The C ompass optimiz er initially mak es rapid pr ogress t owards the solution. While this metho d migh t quick ly appr oach the minimum v alue of an objec tive func tion, it ma y be slo w to det ect this fac t. It may also c onverge v ery slo wly if the le vel sets of the objec tive func tion ar e extremely elonga ted. 44.3.3.2. The NE WUO A O ptimiz er The NE W U nconstr ained Optimiza tion A lgor ithm (NE WUO A) optimiz er [97] (p.4010 ) attempts t o find the least v alue of a func tion , wher e is a par amet er v ector of dimensions . At the star t of every iterative step, a quadr atic mo del appr oxima tion ( ) is c onstr ucted and the minimiza tion is performed on a tr ust r egion (tha t is, a region ar ound the par amet er tha t is limit ed b y an initial par a- met er v ariation). The p erturba tion t o the par amet er v alue needed t o obtain the lo west v alue of is 3179Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.The M esh M orpher/Optimiz erevalua ted dur ing the it eration, and c orrespondingly , the new least v alue of is obtained .The it- erative pr ocess c ontinues un til the tr ust r egion is r educ ed t o the optimiz er convergenc e cr iterion, and the optimiz er e xits with the least v alue of the objec tive func tion. This optimiza tion algor ithm can b e applied t o an y setup c ase of the mesh mor pher/optimiz er. The NE WUO A optimiz er pr ovides the least v alue of the objec tive func tion in a manner tha t is highly accur ate and r obust. The main ad vantage of this optimiz er is tha t it is v ery fast; henc e, this optimiz er is recommended f or pr oblems tha t ha ve a lar ge numb er of par amet ers. 44.3.3.3. The S imple x O ptimiz er The S imple x optimiz er is also r eferred t o as the D ownhill S imple x optimiz er [76] (p.4009 ),[53] (p.4007 ) and the N elder-M ead metho d [82] (p.4009 ). It is based on the idea of geometr ic simple xes; for e xample , a 2D simple x is a tr iangle , and a 3D simple x is a t etrahedr on. For optimiza tion pur poses , ANSY S Fluen t requir es tha t simple xes ar e regular p olyhedr a (tha t is, not degener ate polyhedr a with c ollapsed sides). Each v ertex of the geometr ic simple x represen ts one func tion e valua tion (which in this c ase is one CFD r un), and the numb er of v ertices c orresponds t o the numb er of par amet ers. For the fr ee-f orm def ormation metho d tha t is used b y ANSY S Fluen t to paramet erize changes in shap es, the numb er of ac tive control p oints will det ermine the numb er of vertices of the geometr ic simple x. Minimiza tion of the objec tive func tion is p erformed based on a set of the r ules ab out the “qualit y” of each v ertex.The v ertex qualit y is the v alue of the func tion e valua ted f or each p osition of the c ontrol point. A set of geometr ic op erations such as r eflec tion, expansion, contraction, and shr inking ar e performed in or der t o find the r egion in which t o lo ok f or the minimum of the func tion. Because optimiza tion her e is f ormula ted as a minimiza tion pr oblem, the simple x optimiz er algor ithm seeks the “worst ” vertex, tha t is, the v ertex tha t has the lar gest v alue when the c orresponding par amet er is evalua ted. By performing the r eflec tion ar ound the c enter of the gr avity, the new v alue of the func tion is obtained af ter p erforming the CFD r un. Similar ly, the op erations of e xpansion, contraction, and shr inking ar e used t o obtain the minimum of the func tion. The S imple x optimiz er is k nown t o work well, but it suff ers fr om the lar ge numb er of func tion e valu- ations . It also r equir es smo oth objec tive func tions f or c onvergenc e. 44.3.3.4. The Torczon O ptimiz er The Torczon optimiz er [138] (p.4012 ) is a sligh tly mo dified v ersion of the simple x optimiz er descr ibed previously . Given an initial v ertex, this optimiz er tr ies t o find a b etter v ertex tha t has a func tion v alue that is str ictly less than the func tion v alue a t the pr evious b est v ertex.There ar e thr ee p ossible tr ial steps: the r otation st ep, the e xpansion st ep, and the c ontraction st ep.The algor ithm alw ays comput es the r otation st ep and then t ests t o see if a new b est v ertex has b een iden tified . If it has , then the expansion st ep is c omput ed. Other wise , the algor ithm c omput es and aut oma tically acc epts the c on- traction st ep. 44.3.3.5. The P owell O ptimiz er For the P owell optimiz er, the metho d used is based on the numb er of dimensions of the pr oblem. For optimiza tion pr oblems of single dimension (tha t is, problems with a single par amet er), the golden section sear ch algor ithm [98] (p.4010 ) is used t o find the optimal v alue f or the objec tive func tion. In this algor ithm, the optimal v alue is f ound b y reducing the siz e of the br acketing tr iplet , until the siz e of the br acket (tha t is, the distanc e between the out er p oints of the tr iplet) r eaches a c ertain t oler ance Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3180Design A naly sis and Optimiza tionlevel. In all the c ases , the middle p oint of the new tr iplet is det ermined t o be the b est v alue obtained so far . For multidimensional pr oblems (tha t is, problems with multiple par amet ers), the minimum v alue and the lar gest decr ease is f ound using the golden sear ch algor ithm f or each dimension, in or der t o find the c onjuga te dir ections . A c onjuga te dir ection is a dir ection tha t when sear ched will not alt er the minimum v alue a ttained b y the pr evious mo vemen t in another dir ection—tha t is, a dir ection in which the gr adien t is p erpendicular t o the first dir ection. After finding the N linear ly indep enden t, mutually conjuga te dir ections , one pass will find the e xact minimum v alue . For func tions tha t are not quadr atic, repeated c ycles of N line minimiza tions will c onverge t o minimum. 44.3.3.6. The R osenbr ock O ptimiz er In the R osenbr ock optimiz er [104] (p.4010 ), after the initial dir ection is f ound , multiple st eps ar e tak en in tha t dir ection un til the least v alue is a ttained .The pr ocess star ts with an arbitr ary length . If this initial st ep succ eeds (tha t is, the new v alue of the func tion is less than or equal t o the old v alue), the length is multiplied b y , wher e is mor e than 1. If the st eps fails , the length is multiplied b y , wher e is b etween -1 and 0. The dir ection or the par amet er tha t must b e mo dified is det ermined by ad vancing all the par amet ers b y the st ep length and then selec ting the b est among those tha t yield a func tion v alue tha t is less than the pr evious v alue . After tha t point is acc epted as the b est point, the pr ocess is r epeated.These st eps c ontinue t o repeat un til becomes so small so tha t an y further change in the v alue of does not signific antly r educ e the v alue of the func tion. 44.4. Using the M esh M orpher/Optimiz er The pr ocedur e for setting up and using the mesh mor pher/optimiz er for shap e optimiza tion is as f ollows: 1.Read the c ase in to ANSY S Fluen t. File → Read → Case... 2.If you w ant to use one of the built-in optimiz ers r ather than sp ecifying the def ormation manually or using Design Explor ation in ANSY S Workbench t o explor e multiple def ormation sc enar ios, you will need t o provide an objec tive func tion in one of thr ee w ays: either as a user-defined func tion (UDF), a Scheme sour ce file, or a cust omiz ed func tion tha t is based on output par amet ers (tha t is, values fr om flux, force, surface integral, or v olume in tegral reports).The goal of the optimiz er is t o def orm the mesh in such a w ay tha t this objec tive func tion is minimiz ed. ANSY S Fluen t will r un the solution f or a giv en design stage un til con- vergenc e is r eached , and then check t o see if the objec tive func tion is sa tisfied . If the objec tive func tion is not sa tisfied , ANSY S Fluen t will pr oceed t o the ne xt design, and so on, until convergenc e is achie ved fr om the p oint of view of the optimiz er.You c an sp ecify the optimiz er convergenc e criteria in st ep 12.d .iii. Note tha t if y ou plan t o use the newuoa optimiz er, you must define the objec tive func tion as a UDF . a.If you w ant to pr ovide the objec tive func tion as a user-defined func tion (UDF), perform the st eps tha t follow. For mor e inf ormation ab out UDFs , see the separ ate Fluen t Customiza tion M anual . i.Write a UDF using the DEFINE_ON_DEMAND macr o to define the objec tive func tion. The func tion name must b e objective_function . At the end of the objec tive func tion, the r pvar morph- er/objective_function must b e set t o the (current - target) value . It is this v alue that the optimiz er will a ttempt t o minimiz e. 3181Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the M esh M orpher/Optimiz erii.Compile the UDF using the Compiled UDFs dialo g box. Make sur e libudf app ears as the Libr ary Name . User D efined → User D efined → Func tions → Compiled ... b.If you w ant to pr ovide the objec tive func tion as a Scheme sour ce file , perform the f ollowing st eps: i.Write a Scheme sour ce file t o define the objec tive func tion. The pr ocedur e name must b e object- ive-function . At the end of the objec tive func tion, the r pvar morpher/objective-function must b e set t o the (current - target) value . It is this v alue tha t the optimiz er will a ttempt to minimiz e. ii.Load the Scheme sour ce file (see Reading Scheme S ource Files (p.597) for details). 3.Open the Mesh M orpher/Optimiz er dialo g box by click ing Optimiz er... in the Design ribbon tab ( Para- met er-B ased group b ox). The first time y ou click Optimiz er... in a session, a question dialo g box will ask y ou whether y ou want to enable the mesh mor pher/optimiz er. Click Yes to load the libr aries and op en the Mesh Morpher/Optimiz er dialo g box (Figur e 44.27: The R egions Tab of the M esh M orpher/Optimiz er Dialog Box (p.3183 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3182Design A naly sis and Optimiza tionFigur e 44.27: The Regions Tab of the M esh M orpher/Optimiz er D ialo g Box 4.Specify the manner in which y ou w ould lik e to define the lo cations of the c ontrol p oints, by mak ing a selec tion fr om the Control P oint Distribution list in the Regions tab of the Mesh M orpher/Op- timiz er dialo g box (Figur e 44.27: The R egions Tab of the M esh M orpher/Optimiz er D ialog Box (p.3183 ) and Figur e 44.28: The R egions Tab of the M esh M orpher/Optimiz er D ialog Box for an U nstr uctured Distribution (p.3185 )).Your selec tion her e will also det ermine the k inds of motions y ou c an apply t o the c ontrol p oints (in the Deformation tab). You ha ve the f ollowing choic es: •Regular For this option, the c ontrol p oints ar e spr ead in a r egular distr ibution thr oughout the en tire deformation r egion; you only ha ve to define the numb er of c ontrol p oints along each of the defining dir ection v ectors. Note tha t as par t of this option, the motion of gr oups of c ontrol points will ha ve to be defined as a tr ansla tion, as the abilit y to define r otational or r adial motions is not a vailable . 3183Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the M esh M orpher/Optimiz erLocating c ontrol p oints in this manner is easy and simple , though this c omes a t the c ost of being able t o pr ecisely define c ontrol p oints on sp ecific mesh no des and b oundar ies.This option c an b e a go od choic e in c ases wher e you ar e able t o allo w the en tire mesh within the r egion t o be def ormed—f or e xample , internal flo ws within a pip e or duc t. Note tha t as par t of this option, the mesh def ormation is based on B ernstein p olynomials . While such a dir ect mor phing appr oach is c omputa tionally less e xpensiv e than using r adial basis func tions , it do es not pr ovide y ou with pr ecise c ontrol of a par ticular mesh no de. •Unstr uctured For this option, you will define the lo cations of the c ontrol p oint by right-click ing with the mouse on b oundar y zones , distr ibuting an appr oxima te numb er thr oughout a z one , or b y entering c oordina tes. Note tha t as par t of this option, the motion of gr oups of c ontrol p oints can b e defined as a tr ansla tion, as a r otation ab out a p oint / axis , or r adially ab out a p oint / axis. This option pr ovides gr eat precision with r egar d to the lo cation of the c ontrol p oints; this allows you t o mor ph par ticular no des and r egions of the mesh, as w ell as t o pr eser ve features within the def ormation r egion (as y ou c an mak e no des sta tionar y by applying a par amet er value of z ero).This option also allo ws you t o easily define t wisting and axisymmetr ical motions . This ma y be a go od choic e for e xternal flo ws and aer odynamic applic ations . Note tha t as par t of this option, the mesh def ormation is based on r adial basis func tions . While this is c omputa tionally mor e expensiv e than using B ernstein p olynomials (b ecause it involves the solution of a sy stem of equa tions), it allo ws you t o ha ve pr ecise c ontrol of a particular mesh no de if y ou ha ve created a c ontrol p oint with the same c oordina tes. Note tha t all of the def ormation r egions tha t you define in the ne xt step must use the same Control Point Distribution ; if y ou change this selec tion a t an y point, all of the settings in the Regions tab will b e delet ed. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3184Design A naly sis and Optimiza tionFigur e 44.28: The Regions Tab of the M esh M orpher/Optimiz er D ialo g Box for an U nstr uctured Distribution 5.Define the r egion(s) of the domain wher e the mesh will b e def ormed in or der t o optimiz e the shap e, by performing the f ollowing st eps. Each def ormation r egion will b e defined as a “box”, tha t is, a rectangle f or 2D c ases and a r ectangular he xahedr on f or 3D c ases . Imp ortant It is r ecommended tha t you define each def ormation r egion t o be bigger than the ar ea of in terest, in or der t o main tain pr oper continuit y between def orming and non-def orming regions . a.In the Regions tab , enter a name f or a def ormation r egion in the t ext-en try box at the t op of the Name group b ox. 3185Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the M esh M orpher/Optimiz erb.You ha ve the option of using the b oundar y zones t o create a b ounding b ox for the def ormation r egion; this b ox can r epresen t the final sc ope of the r egion, or it c an ac t as a star ting p oint tha t is fur ther r efined by manually editing the or igin, direction v ectors, and siz e of the r egion (as descr ibed in the st eps tha t follow). Perform the f ollowing st eps in the Update from Z ones group b ox: i.Selec t the z ones fr om the Boundar y Zones list tha t best r epresen t the e xtents of the def ormation region y ou w ould lik e to create. ii.Click the Define butt on in the Bounding B ox group b ox to up date the v alues in the Origin , Direction-1 Vector,Direction-2 Vector (for 3D c ases), and Size of Region group b oxes. Note tha t the b ounding b ox will b e pr eview ed in gr een in the gr aphics windo w when y ou click an y of the Bounding B ox butt ons. iii.You c an incr ease or decr ease the siz e of the b ounding b ox by click ing the Enlar ge and Reduc e butt ons, respectively. Note tha t you ha ve the option of setting the sc aling fac tors asso ciated with these butt ons via the f ollowing t ext commands: define → mesh-morpher-optimizer → region → scaling-enlarge define → mesh-morpher-optimizer → region → scaling-reduce c.You ha ve the option of using the line t ool (f or 2D c ases) or the plane t ool (f or 3D c ases) t o define the direction v ectors of the def ormation r egion; the v alues defined c an r epresen t the final c omp onen ts of the v ectors, or the y can ac t as a star ting p oint tha t is fur ther r efined b y manually editing the dir ection vectors (as descr ibed in the st eps tha t follow). Set up the line t ool or the plane t ool (as descr ibed in Using the Line Tool (p.2740 ) and Using the P lane Tool (p.2744 ), respectively), and then click the Update from Line Tool or Update from P lane Tool butt on t o up date the v alues in the Direction-1 Vector and (f or 3D c ases) Direction-2 Vector group b oxes. d.Define an or igin f or the def ormation r egion b y en tering the C artesian c oordina tes of a p oint in the X,Y, and (f or 3D) Z numb er-en try boxes in the Origin group b ox. Note tha t as y ou en ter values , you c an view the r esulting b ounding b ox (in gr een) b y click ing the Preview butt on. e.Define the first dir ection v ector of the def ormation r egion r elative to the Origin coordina tes, by en tering values in the X,Y, and (f or 3D) Z numb er-en try boxes in the Direction-1 Vector group b ox. For 2D c ases , ANSY S Fluen t will aut oma tically define the sec ond dir ection v ector of the def orm- ation r egion t o be perpendicular t o the Direction-1 Vector, and will displa y the c omp onen ts in the uneditable Direction-2 Vector group b ox. f.For 3D c ases , define the sec ond dir ection v ector of the def ormation r egion r elative to the Origin co- ordina tes, by en tering v alues in the X,Y, and Z numb er-en try boxes in the Direction-2 Vector group box. If the v ector y ou define is not p erpendicular t o the Direction-1 Vector, ANSY S Fluen t will aut oma t- ically r edefine the sec ond v ector to be the pr ojec tion of the Direction-2 Vector you en tered on to a plane tha t is p erpendicular t o the Direction-1 Vector. Based on this definition, the Direction-2 Vector you define c annot b e colinear with the Direction-1 Vector. The thir d dir ection v ector of the def ormation r egion will b e aut oma tically defined as the cr oss produc t of the first and sec ond dir ection v ectors. g.Define the o verall dimensions of the def ormation r egion b y en tering length v alues f or Direction-1 , Direction-2 , and (f or 3D c ases) Direction-3 in the Size of Region group b ox. h.Create control p oints within the def ormation r egion. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3186Design A naly sis and Optimiza tioni.If you selec ted Regular for the Control P oint Distribution , define the numb er of c ontrol p oints you w ant along each dir ection v ector of the def ormation r egion b y en tering v alues f or Direction- 1,Direction-2 , and (f or 3D c ases) Direction-3 in the Control P oints group b ox.The t otal numb er of control p oints for the r egion will b e the pr oduc t of the numb ers y ou en ter. Incr easing the numb er of control p oints allo ws you gr eater control of the def ormation, but also incr eases the c omputa tional expense . Imp ortant When y ou define multiple def ormation r egions , you must ensur e tha t all the de- formation r egions ha ve the same t otal numb er of c ontrol p oints. Save the settings y ou ha ve created f or the def ormation r egion b y click ing the Create butt on. The name of the def ormation r egion will b e added (and selec ted) in the selec tion list a t the bottom of the Name group b ox, and the c ontrol p oints and b ounding b ox of the def ormation region will b e displa yed in blue in the gr aphics windo w (see Figur e 44.29: Displa ying the Control P oints for a R egular D istribution (p.3187 )). If you do not w ant the c ontrol p oints and bounding b ox displa yed in the gr aphics windo w, you c an deselec t the it em b y click ing the butt on lo cated ab ove the r ight side of the Name selec tion list. Figur e 44.29: Displa ying the C ontrol P oints for a Regular D istribution A new default name will b e aut oma tically en tered in the t ext-en try box at the t op of the Name group b ox, in pr epar ation f or an y def ormation r egions y ou w ant to cr eate in the futur e. ii.If you selec ted Unstr uctured for the Control P oint Distribution , click the Create butt on t o sa ve the settings f or the def ormation r egion, as y ou need an e xisting r egion t o be able t o create control points.The name of the def ormation r egion will b e added (and selec ted) in the selec tion list a t the bottom of the Name group b ox, and the b ounding b ox will b e displa yed in blue in the gr aphics windo w (see Figur e 44.31: Displa ying the C ontrol Points for an U nstr uctured D istribution (p.3190 )). If at an y point you do not w ant the b ounding b ox displa yed in the gr aphics windo w, you c an deselec t the it em b y click ing the butt on lo cated ab ove the r ight side of the Name selec tion list. 3187Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the M esh M orpher/Optimiz erNext, examine the settings in the Boundar y Continuit y group b ox. By default , the mesh mor pher/optimiz er is set t o pr ovide smo oth mesh tr ansitions wher ever the mesh in tersec ts with the limits of the def ormation r egion (tha t is, the sides of the b ounding b ox).This is ac- complished thr ough the cr eation of sta tionar y control p oints at those in tersec tions; by default , these c ontrol p oints ar e hidden, though y ou c an view them b y enabling the Displa y Control Points option. If you w ould lik e to allo w mor e abr upt mesh tr ansitions a t the b oundar ies of the r egion, you c an disable the Smooth Transitions option. The ne xt step is t o cr eate control p oints. Click the Define ... butt on in the Control P oints group b ox to op en the Define C ontrol P oints dialo g box (Figur e 44.30: The D efine C ontrol Points D ialog Box (p.3188 )). Figur e 44.30: The D efine C ontrol P oints D ialo g Box Use the Define C ontrol P oints dialo g box to cr eate control p oints within the r egion. You have the f ollowing options: •Click the Mouse-P robe butt on and then pr obe (using the r ight mouse butt on, by default) within the def ormation r egion. For 3D c ases , if you pr obe on a displa yed b oundar y, the c ontrol p oint will b e located a t tha t point on tha t boundar y. Note tha t it ma y be helpful t o revise wha t sur faces are displa yed using the Mesh D ispla y Dialog Box (p.3239 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3188Design A naly sis and Optimiza tion•Make a selec tion fr om the Zones list, enter an Appr oxima te Numb er of c ontrol p oints that you w ant on tha t zone , and click the Distribut e butt on.This metho d uses B inar y Space Partitioning (BSP) t o agglomer ate the c ell fac es of the z one within the b ounding box based on the in tended numb er of c ontrol p oints, and then a c ontrol p oint is assigned to the no de tha t is closest t o the c entroid of each agglomer ation. While this metho d is convenien t when y ou w ant a lar ge numb er of c ontrol p oints or w ant to mor ph en tire boundar y zones or sur faces, ther e ar e some limita tions t o BSP : the numb er of c ontrol p oints may exceed the v alue y ou en ter, and the c ontrol p oints will not b e as e venly distr ibut ed on cur ved sur faces when c ompar ed t o fla t sur faces. •Enter X,Y, and Z coordina tes and click the Create butt on.This metho d allo ws you t o locate a control p oint dir ectly on a mesh no de, if you ha ve first obtained the v ertex position (which c an be displa yed in the c onsole if y ou selec t long descr iption from the Probe drop-do wn list in the View tab ( Mouse group b ox) and then pr obe near the no de with the mouse). •If you ha ve pr eviously gener ated an ASCII t ext file tha t contains c ontrol p oint definitions , you c an read it b y click ing Read ... and using the dialo g box tha t op ens. Using a t ext file c an b e helpful when y ou ha ve a lar ge numb er of p oints. It is not nec essar y to create the t ext file fr om scr atch, as y ou c an cr eate a simplified t ext file with sample da ta using the Write... butt on, and then define the bulk of the c ontrol p oint locations using a spr eadsheet pr ogram. See Mesh M orpher/Optimiz er File F ormats (p.3986 ) for details ab out the f ormat of the t ext file . The c ontrol p oints will b e displa yed in gr een in the gr aphics windo w, and will tur n red when selec ted in the Control P oints selec tion list. When a c ontrol p oint is selec ted, you also ha ve the abilit y to Delet e it, or en ter new c oordina tes and Modify it. When adding c ontrol p oints, rememb er tha t it ma y be helpful t o lo cate them not only in areas tha t you w ant to def orm, but also on f eatures in the def ormation r egion tha t you w ant to pr eser ve (as y ou c an mak e no des sta tionar y by applying a par amet er v alue of z ero).When you ar e done adding c ontrol p oints, click OK to close the Define C ontrol P oints dialo g box. 3189Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the M esh M orpher/Optimiz erFigur e 44.31: Displa ying the C ontrol P oints for an U nstr uctured D istribution A new default name will b e aut oma tically en tered in the t ext-en try box at the t op of the Name group b ox, in pr epar ation f or an y def ormation r egions y ou w ant to cr eate in the futur e. i.Create an y additional def ormation r egions as nec essar y by repeating st eps 5.a.–h. Imp ortant Overlapping def ormation r egions ar e not supp orted. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3190Design A naly sis and Optimiza tionj.If you need t o mo dify a def ormation r egion a t an y point, selec t it in the Name selec tion list , revise the appr opriate settings , and click the Modify butt on.The up dated c ontrol p oints and b ounding b ox will be displa yed in the gr aphics windo w. Imp ortant When mo difying an e xisting def ormation r egion, be sur e to click Modify rather than Create. If you click Create, you will not mo dify the def ormation r egion, but will inst ead create a new one with the mo dified settings . k.If you need t o delet e a def ormation r egion a t an y point, selec t it in the Name selec tion list and click the Delet e butt on. 6.You ha ve the option of defining c onstr aints on the b oundar y zones , in or der t o limit the fr eedom of par tic- ular z ones tha t fall within the def ormation r egion(s) dur ing the mor phing of the mesh. The following options are available: •unconstr ained This option sp ecifies tha t the b oundar y zone is c omplet ely fr ee t o be def ormed acc ording t o the assigned par amet ers. By default , all w all z ones ar e unc onstr ained . •fixed This option sp ecifies tha t the b oundar y zone is fix ed and will not b e def ormed . None of the z ones are fix ed b y default. Imp ortant If you sp ecify one or mor e fix ed b oundar y zones in a def ormation r egion, you must ensur e tha t ther e is a t least one unc onstr ained b oundar y zone in the r egion as w ell. •passiv e This option sp ecifies tha t the no des of the b oundar y zone ar e par tially c onstr ained t o varying degr ees, based on their pr oximit y to adjac ent boundar y zones tha t are fix ed.The no des in a passiv e boundar y zone b ehave in a similar manner t o the in terior mesh no des, in or der t o ensur e that ther e is a smo oth tr ansition b etween fix ed and unc onstr ained b oundar y zones . By default , all b oundar y zones tha t are not w alls (f or e xample , inlets , outlets , symmetr y, and p eriodic boundar ies) ar e passiv e. To define the c onstr aints on the b oundar y zones , perform the f ollowing st eps. a.Click the Constr aints tab ( Figur e 44.32: The C onstr aints Tab of the M esh M orpher/Optimiz er D ialog Box (p.3192 )). 3191Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the M esh M orpher/Optimiz erFigur e 44.32: The C onstr aints Tab of the M esh M orpher/Optimiz er D ialo g Box b.To revise the default c onstr aints on the b oundar y zones , selec t the z one name(s) fr om the Zones selec tion list in the Constr aints group b ox, and then selec t either Unconstr ained ,Passiv e, or Fixed from the Option list. c.Click Displa y if y ou w ant view the b oundar y zones selec ted fr om the Zones selec tion list , in order t o verify the z ones f or which y ou ar e defining c onstr aints. d.Click Summar y if you w ould lik e to pr int a list in the c onsole tha t summar izes the c onstr aint definitions for all of the b oundar y zones . 7.Begin the def ormation definition b y defining the par amet ers. a.Click the Deformation tab ( Figur e 44.33: The D eformation Tab of the M esh M orpher/Optimiz er D ialog Box (p.3193 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3192Design A naly sis and Optimiza tionFigur e 44.33: The D eformation Tab of the M esh M orpher/Optimiz er D ialo g Box b.Enter the Numb er of P aramet ers tha t will b e used t o define the def ormation. This numb er ma y be as low as the maximum numb er of par amet ers y ou will define on a single c ontrol p oint, or as high as the total numb er of par amet ers y ou will set on all of the c ontrol p oints combined . c.If you w ant to manually sp ecify the def ormation or use D esign Explor ation in ANSY S Workbench to explor e multiple def ormation sc enar ios (r ather than using the built-in optimiz ers), define the paramet er fields in the Paramet er Values group b ox. Note tha t these fields ar e only a vailable when none or workbench is selec ted fr om the Optimiz er drop-do wn list in the Optimiz er tab . The v alue of the par amet er defines a magnitude tha t will then b e used along with other dir ection settings t o define motions tha t produce an o verall displac emen t for a giv en c ontrol p oint.The value will sp ecify a length in met ers f or tr ansla tions and r adial motions , and will sp ecify an angle in degr ees f or rotations; the units her e will b e used r egar dless of wha t units y ou ar e using in the c ase. For each par amet er y ou ha ve the f ollowing options: 3193Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the M esh M orpher/Optimiz er•Enter a c onstan t numer ic value . Note tha t ha ving a par amet er with a v alue of z ero allo ws you t o mak e a c ontrol p oint sta tionar y. •Use the dr op-do wn menu t o define the par amet er thr ough an e xpression or input par amet er (f or example , as par t of a par ametr ic stud y managed b y Workbench); for details , see Directly A pplied Expr essions (p.665) or Creating a N ew P aramet er (p.845), respectively. When y ou ha ve finished defining the par amet er fields , click the Apply butt on in the Paramet er Values group b ox to sa ve the definitions . d.You ha ve the option of limiting ho w much each par amet er is allo wed t o def orm b y defining str ict minimum and maximum v alues .This c an b e useful when y ou need t o keep the par amet ers within a certain t oler ance of the initial design, or when y ou k now in ad vance tha t certain designs ar e impr actical. While this option is t ypic ally used with the built-in optimiz ers, it is a vailable f or manual def ormation, so tha t you c an visualiz e the eff ects of the b ounds and set them in teractively. Note tha t this option is not a vailable when workbench is selec ted fr om the Optimiz er drop-do wn list in the Optimiz er tab . Click the Set B ounds ... butt on in the Paramet er Values group b ox to op en the Paramet er Bounds dialo g box (Figur e 44.34: The P aramet er B ounds D ialog Box (p.3194 )). Figur e 44.34: The P aramet er B ounds D ialo g Box Selec t the par amet ers y ou w ant to limit fr om the Paramet ers selec tion list , disable the Unboun- ded option in the Range group b ox, and then en ter appr opriate values f or Min and Max. At an y point you c an click the Apply butt on t o sa ve your b ounds , and y ou c an click the Summar y butt on t o displa y a summar y of the sa ved b ounds in the c onsole .When all of the par amet er bounds ar e defined t o your sa tisfac tion, click the OK butt on t o close the Paramet er B ounds dialo g box. 8.If you selec ted Regular for the Control P oint Distribution in the Regions tab , perform the f ollowing steps.You will define motion settings f or the c ontrol p oints b y selec ting par amet ers (which y ou defined pr eviously) and sp ecifying the tr ansla tion dir ection, thus c ompleting the def ormation definition. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3194Design A naly sis and Optimiza tiona.Click the Motion S ettings ... butt on in the Deformation tab t o op en the Motion S ettings dialo g box (Figur e 44.35: The M otion S ettings D ialog Box for a R egular D istribution (p.3195 )). Figur e 44.35: The M otion S ettings D ialo g Box for a Regular D istribution b.(optional) I f you ha ve pr eviously gener ated an ASCII t ext file tha t contains motion settings , you c an read it b y click ing Read ... at the b ottom of the Motion S ettings dialo g box and using the dialo g box that op ens; other wise , you should pr oceed t o steps 8.c .–8.j . and define the settings using the other controls in the Motion S ettings dialo g box. Using a t ext file c an b e helpful when y ou ha ve a lar ge numb er of motion settings . It is not ne- cessar y to cr eate the t ext file fr om scr atch, as y ou c an cr eate a simplified t ext file with sample values using the Write... butt on (as descr ibed in st ep 8.k.), and then add the bulk of the motion 3195Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the M esh M orpher/Optimiz ersettings using a spr eadsheet pr ogram. See Mesh M orpher/Optimiz er F ile F ormats (p.3986 ) for details about the f ormat of the t ext file . Imp ortant Immedia tely af ter y ou r ead a t ext file , the Motion S ettings dialo g box will not displa y the applied settings .To begin viewing the applied settings , mak e a selec tion fr om the Region ,Control P oints, and Paramet ers lists , and the asso ciated Transla tion Direction will b e displa yed. You c an then edit the motion settings as nec essar y (in a manner similar t o steps 8.c .–8.g .) and/or proceed t o step 8.m. c.Make a selec tion fr om the Region drop-do wn list in the Motion S ettings dialo g box. d.Specify the c ontrol p oints in the cur rent Region to which y ou w ant to assign the same motion settings (tha t is, the same c ombina tion of par amet ers and dir ection). You c an sp ecify these c ontrol p oints using one or mor e of the f ollowing metho ds: •Selec t the ID numb ers fr om the Control P oints selec tion list. The selec ted c ontrol p oints will b e highligh ted in the gr aphics windo w. •Click the Mouse-P robe butt on in the Selec tion Tools group b ox and then click the c ontrol p oints in the gr aphics windo w with the mouse-pr obe butt on (which is the r ight mouse butt on, by default). To deselec t, selec t a highligh ted c ontrol p oint with the mouse-pr obe butt on. As you selec t the c ontrol points, the y will also b e selec ted in the Control P oints selec tion list. •Use the Inde xed G rouping group b ox to selec t the c ontrol p oints based on their assigned indic es. Each c ontrol p oint has i,j, and (f or 3D c ases) k inde x numb ers, each of which denot e its plac e in the sequenc e (star ting a t the or igin of the r egion) of c ontrol p oints along the dir ection-1, direction-2, and dir ection-3 v ectors, respectively (as defined in the Regions tab of the Mesh M orpher/Optimiz er dialo g box).You c an mak e selec tions fr om the inde x dr op-do wn lists , and then click the Selec t butt on. In a similar w ay you c an deselec t control p oints using the Deselec t butt on. As you selec t the c ontrol points, the y will also b e selec ted in the Control P oints selec tion list and highligh ted in the gr aphics windo w. For e xample , consider the c ase of a 3D r egion: if y ou selec t 2 from the k drop-do wn list , the control p oints in the sec ond plane p erpendicular t o the dir ection-3 v ector (tha t is, the dir ection- 1–dir ection-2 plane) will b e selec ted. If you selec t 1 from b oth the i and j drop-do wn lists , the line of c ontrol p oints at the in tersec tion of the first planes p erpendicular t o the dir ection-1 and dir ection-2 v ectors will b e selec ted. Making selec tions fr om all thr ee dr op-do wn lists will selec t a single c ontrol p oint. e.Make selec tions fr om the Paramet ers selec tion list , in or der t o sp ecify those y ou w ant to assign (along with a tr ansla tion dir ection) t o the selec ted Control P oints. Note tha t the v alues asso ciated with these paramet ers (as displa yed in the Paramet er Values group b ox in the Deformation tab of the Mesh Morpher/Optimiz er dialo g box) ar e irrelevant if y ou plan t o use the built-in optimiz ers. f.Define the Transla tion D irection tha t will b e asso ciated with the selec ted Paramet ers by en tering values f or the X,Y, and (f or 3D c ases) Z directions . Note tha t you do not need t o define a unit v ector. If you use a built-in optimiz er, these v alues will pr ovide the dir ection of the displac emen t of the control p oint and the optimiz er will det ermine the o verall magnitude of displac emen t. Alternat- Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3196Design A naly sis and Optimiza tionively, if y ou sp ecify the def ormation manually or using D esign Explor ation, the v alues y ou en ter in the Transla tion D irection group b ox will b e multiplied with the v alues of the Paramet ers to define the displac emen t applied t o the c ontrol p oints. g.Click the Apply butt on t o sa ve the motion settings . h.If you w ant to apply another set of motion settings t o the selec ted Control P oints, repeat steps 8.e .–8.g . for each additional c ombina tion of par amet ers and dir ection. i.Repeat steps 8.d .–8.h. for each additional set of c ontrol p oints in the cur rent Region to which y ou w ant to assign motion settings . j.Repeat steps 8.c .–8.i. for each additional r egion in which y ou w ant to apply def ormation par amet ers to control p oints. k.If you w ant to sa ve all of the settings y ou sp ecified in the Motion S ettings dialo g box as an ASCII t ext file, click Write... and sp ecify a name in the dialo g box tha t op ens.You c an edit the motion settings in this t ext file using a spr eadsheet pr ogram, and then r ead it in this or a separ ate case file , as descr ibed in st ep 8.b . l.You c an displa y a summar y of the motion settings in the c onsole b y click ing the Summar y butt on. m.Click OK to close the Motion S ettings dialo g box. 9.If you selec ted Unstr uctured for the Control P oint Distribution in the Regions tab , perform the following st eps.You will define one or mor e motions—which c onsist of a par amet er (defined pr evi- ously), direction settings , and the aff ected c ontrol p oints—and thus c omplet e the def ormation definition. Imp ortant When a single c ontrol p oint is asso ciated with multiple motions , not e tha t the r esultan t displac emen t for each individual motion will b e calcula ted fr om the or iginal p osition, and then the displac emen ts will b e summed .This means tha t the or der in which the motions ar e created will ha ve no eff ect on the final lo cation of the c ontrol p oint. a.Click the Motion S ettings ... butt on in the Deformation tab t o op en the Motion S ettings dialo g box (Figur e 44.36: The M otion S ettings D ialog Box for an U nstr uctured D istribution (p.3198 )). 3197Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the M esh M orpher/Optimiz erFigur e 44.36: The M otion S ettings D ialo g Box for an U nstr uctured D istribution b.(optional) I f you ha ve pr eviously gener ated an ASCII t ext file tha t contains motion definitions , you c an read it b y click ing Read ... at the b ottom of the Motion S ettings dialo g box and using the dialo g box that op ens; other wise , you should pr oceed t o steps 9.c .–9.k. and define the settings using the other controls in the Motion S ettings dialo g box. Using a t ext file c an b e helpful when y ou ha ve a lar ge numb er of motions . It is not nec essar y to create the t ext file fr om scr atch, as y ou c an cr eate a simplified t ext file with sample v alues using the Write... butt on (as descr ibed in st ep 9.l.), and then add the bulk of the motion definitions using a spr eadsheet pr ogram. See Mesh M orpher/Optimiz er F ile F ormats (p.3986 ) for details ab out the f ormat of the t ext file . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3198Design A naly sis and Optimiza tionYou c an then either add additional motions (in a manner similar t o steps 9c .–9.h.) or mo dify / delet e an e xisting motion (as descr ibed in st eps 9.i. and 9.j .).When the settings ar e finaliz ed, you can pr oceed t o step 9.k. c.To begin defining a new motion, mak e a selec tion fr om the Paramet er drop-do wn list. d.Make a selec tion fr om the Type list, to indic ate the t ype of motion y ou w ould lik e to define .You c an specify tha t a gr oup of c ontrol p oints under goes a Transla tion , a Rota tion about a p oint (for 2D) or an axis (f or 3D), or a Radial motion ab out a p oint (for 2D) or an axis (f or 3D). e.Define the motion b y en tering X,Y, and (f or 3D c ases) Z values f or the f ollowing: the Direction used for tr ansla tions; or the Axis Or igin and (f or 3D c ases) Axis D irection used f or rotations and r adial mo- tions . For Direction or Axis D irection , not e tha t you do not need t o define unit v ectors. If you use a built-in optimiz er, the v alues y ou en ter will define the dir ection of the displac emen t of the c ontrol p oint and the optimiz er will det ermine the o verall magnitude of displac emen t. Alternatively, if y ou sp ecify the def ormation manually or using D esign Explor ation, the magnitude will b e the v alue of the Paramet er; transla tion is a sp ecial c ase, in which the v alues y ou en ter in the Direction group b ox are multiplied with the v alue of the Paramet er to define the displac e- men t applied t o the c ontrol p oints. f.Selec t the c ontrol p oints to which y ou w ant to assign the selec ted motion. You c an either selec t them in the Control P oints list, or click the Mouse-P robe butt on and click the c ontrol p oints in the gr aphics windo w using the mouse-pr obe butt on (which is the r ight mouse butt on, by default). g.A default name will b e gener ated in the t op field of the Name group b ox, based on the Type and Paramet er of the motion. You c an edit this t ext to mak e it mor e descr iptiv e, as nec essar y. h.Click Create to create the motion. The name will b e added t o the selec tion list in the Name group b ox. i.Repeat steps 9.c .–9.g . for each additional motion tha t you w ould lik e to create. j.If you need t o mo dify a motion a t an y point, selec t it in the lo wer selec tion list in the Name group b ox, revise the appr opriate settings , and click the Modify butt on. Imp ortant When mo difying an e xisting motion, be sur e to click Modify rather than Create. If you click Create, you will not mo dify the motion, but will inst ead cr eate a new one with the mo dified settings . k.If you need t o delet e a def ormation r egion a t an y point, selec t it in the lo wer selec tion list in the Name group b ox and click the Delet e butt on. l.You c an displa y a summar y of the motion definitions in the c onsole b y click ing the Summar y butt on. m.If you w ant to sa ve all of the settings y ou sp ecified in the Motion S ettings dialo g box as an ASCII t ext file, click Write... and sp ecify a name in the dialo g box tha t op ens.You c an edit the motion settings in this t ext file using a spr eadsheet pr ogram, and then r ead it in this or a separ ate case file , as descr ibed in st ep 9.b . 3199Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the M esh M orpher/Optimiz er10.If you w ant to manually sp ecify the def ormation (tha t is,none is selec ted fr om the Optimiz er drop- down list in the Optimiz er tab of the Mesh M orpher/Optimiz er dialo g box), perform the f ollowing steps: a.Click the Deform butt on t o apply the cur rent settings (in the Paramet er Values group b ox and Motion Settings dialo g box) and t o displa y the def ormed mesh in the gr aphics windo w.The Deform butt on allows you t o manually sp ecify the def ormation. b.You c an click the Check butt on t o pr int out a mesh check r eport in the c onsole f or the cur rently displa yed mesh. The mesh check r eport is the same as tha t produced b y the Check butt on in the Gener al task page , as descr ibed in Mesh C heck R eport (p.789). Imp ortant If you sa ve par amet er settings but do not click the Deform butt on, the mesh check report will not acc oun t for the mesh tha t is pr oduced fr om those settings . c.Click the Reset butt on if y ou w ant to revert to the or iginal mesh without the def ormations tha t result from the Deform butt on. 11.If you plan t o use the built-in optimiz ers, you should decide whether y ou w ant to disable the gener al mesh check tha t is p erformed b y default immedia tely af ter the mesh is def ormed in e very design stage .The mesh check tha t is p erformed is the same as tha t initia ted b y the Check butt on in the Gener al task page (see Check ing the M esh (p.788) for details). If any errors ar e disc overed, the mesh is r ejec ted and the ne xt design stage is a ttempt ed. Disabling the gener al mesh check allo ws you t o repair the mesh, so tha t an accur ate solution c an be calcula ted f or it. Note tha t you c an set up the mesh r epair b y en tering the appr opriate text commands (as descr ibed in Repair ing M eshes (p.790)) in the Initial C ommands text-en try box in the Optimiz er tab . You c an disable the gener al mesh check b y using the f ollowing t ext command: define → mesh-morpher-optimizer → optimizer-parameters → disable-mesh- check 12.If you w ant to use the built-in optimiz ers, define the optimiz er settings and initia te the optimiza tion pr ocess. a.Click the Optimiz er tab ( Figur e 44.37: The Optimiz er Tab of the M esh M orpher/Optimiz er D ialog Box (p.3201 )). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3200Design A naly sis and Optimiza tionFigur e 44.37: The Optimiz er Tab of the M esh M orpher/Optimiz er D ialo g Box b.Selec t an optimiz er fr om the Optimiz er drop-do wn list. The a vailable optimiz ers ar e not based on gradien ts, and include the f ollowing: compass ,newuoa ,powell,rosenbr ock,simple x, and torczon. For mor e inf ormation ab out ho w these optimiz ers func tion, see Optimiz ers (p.3179 ). c.Click the Objec tive Func tion D efinition... butt on t o op en the Objec tive Func tion D efinition dialo g box (Figur e 44.38: The O bjec tive Function D efinition D ialog Box (p.3202 )). 3201Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the M esh M orpher/Optimiz erFigur e 44.38: The O bjec tive Func tion D efinition D ialo g Box i.Make a selec tion in the Options group b ox to sp ecify whether the objec tive func tion tha t will b e minimiz ed dur ing the optimiza tion pr ocess is a User-D efined F unc tion , a Scheme P rocedur e, or a cust omiz ed func tion of output par amet ers as defined b y the Custom C alcula tor.Your selec tion should c orrespond with the ac tions y ou t ook in st ep 2. ii.If you selec ted Custom C alcula tor in the pr evious st ep, define the objec tive func tion via the GUI controls in the Custom C alcula tor group b ox. As you click the butt ons in this gr oup b ox, text and symb ols will app ear in the Func tion t o M inimiz e text box.You cannot edit the c ontents of this b ox directly; if you w ant to delet e par t or all of the func tion, use the DEL or Clear butt on, respectively. You c an include output par amet ers in the definition of the func tion b y mak ing a selec tion from the Output P aramet ers list and click ing Selec t. If you w ant to add a new output paramet er to the selec tion list or check the definition of an e xisting one , you c an click the Paramet ers... butt on and use the Paramet ers dialo g box (as descr ibed in Creating Output Paramet ers (p.2935 )); be sur e to click the Refr esh butt on when y ou r etur n to the Objec tive Func tion D efinition dialo g box, so tha t the Output P aramet ers list is up dated.You c an also use Operators to manipula te the output par amet ers in the func tion. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3202Design A naly sis and Optimiza tionYou c an click the Apply butt on a t an y point to sa ve your func tion. When it is fully defined , click the OK butt on t o sa ve your settings and close the Objec tive Func tion D efinition dialo g box. d.Define the settings in the Optimiz er S ettings group b ox. i.Enter a v alue f or Maximum N umb er of D esigns , to sp ecify the maximum numb er of design stages the optimiz er will under go t o reach the sp ecified objec tive func tion. Note tha t this numb er is not the numb er displa yed in the c onsole dur ing the optimiza tion pr ocess. Each optimiz er under goes a certain numb er of design mo dific ations (c alled “runs”) before it c onverges t o a design f or a par ticular design stage .The Run numb er displa yed in the c onsole r efers t o the ac tual design mo dific ations (including the inner lo op) ir respective of the optimiz er, wher eas the Maximum N umb er of D esigns value is the maximum numb er of c onverged designs pr ovided b y the optimiz er. ii.Enter the Maximum I terations p er D esign , to sp ecify the maximum numb er of it erations ANSY S Fluen t performs f or each design change . iii.Enter a numb er for Optimiz er C onvergenc e Criteria, to sp ecify the c onvergenc e criteria for the optimiz er. iv.If you selec ted the newuoa optimiz er, enter a numb er for the Initial P aramet er Variation to sp ecify how much the par amet ers will b e allo wed t o vary dur ing the initial c alcula tions .This v alue is not intended t o define a str ict minimum / maximum f or the par amet ers (as is defined b y the b ounds specified using the Paramet er B ounds dialo g box), but should only b e lar ge enough t o allo w the optimiz er to captur e the minima. A b etter estima tion (tha t is, a smaller v alue) allo ws the optimiz er to reach c onvergenc e fast er. e.By default , the or thogonal qualit y (as defined in Mesh Q ualit y (p.719)) of the initial and e very subsequen t mesh is c omput ed, before the r elated solution c alcula tion is initia ted. If the or thogonal qualit y for an y cell is less than a sp ecified v alue , the mesh is r ejec ted and F luen t proceeds t o the ne xt design stage (ther efore helping t o ensur e tha t your solution accur acy is not c ompr omised b y poor qualit y meshes). These ac tions ar e go verned b y the settings in the Mesh Q ualit y group b ox. If you do not w ant the meshes r ejec ted based on their or thogonal qualit y, you c an disable the Rejec t Poor Q ualit y M eshes option; other wise , specify the minimum or thogonal qualit y tha t must b e main tained b y every cell b y en tering a v alue fr om 0–1 (wher e 0 represen ts the w orst qualit y) for Minimum Or tho gonal Q ualit y.When det ermining an appr opriate minimum v alue , you c an check the or thogonal qualit y of the initial mesh (b y using the Rep ort Qualit y butt on in the Gener al task page) and then selec t a v alue tha t is sufficien tly lo wer, so as not t o rejec t a major ity of the meshes gener ated dur ing the optimiza tion pr ocess. f.You ha ve the option of sa ving in termedia te case and da ta files dur ing the optimiza tion r un, so tha t you can r estar t an in terrupted solution in the same or a diff erent Fluen t session without incr easing the overall numb er of design it erations needed t o reach c onvergenc e.To enable the sa ving of such in ter- media te files , define the settings in the Case and D ata F ile S et group b ox. i.Specify the fr equenc y (in numb er of design it erations) tha t you w ant the in termedia te case and data files sa ved b y en tering a v alue f or Save Every.The default v alue is 0, which sp ecifies tha t no intermedia te files will b e sa ved. Note tha t if y ou selec ted the newuoa optimiz er, the fr equenc y at which files ar e sa ved ma y not e xactly c orrespond t o the numb er you en ter, but should b e reasonably close . ii.Specify the maximum numb er of in termedia te files sets y ou w ant to retain b y en tering a v alue f or Maximum N umb er Retained . After the maximum limit of file sets has b een sa ved, ANSY S Fluen t 3203Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the M esh M orpher/Optimiz erbegins o verwriting the ear liest e xisting in termedia te file set. Lower values should b e used if y ou have limit ed disk spac e or y ou ar e concerned ab out sa ving unnec essar y files . iii.Specify a r oot name f or the in termedia te files in the File N ame text box.When the files ar e sa ved, the design it eration will b e app ended t o this r oot name t o indic ate the p oint at which it w as sa ved during the optimiza tion r un. An extension will also b e aut oma tically added t o the r oot name (.cas or .dat ).You c an include a f older pa th in the filename if y ou w ant the files sa ved outside of the working f older . g.Specify ho w the solution v ariables should b e treated af ter the mesh is def ormed b y mak ing a selec tion from the Metho d list in the Initializa tion group b ox: •Selec t Initializ e Data A fter M orphing to sp ecify tha t the solution v ariables should b e initializ ed t o the v alues sp ecified in the Solution Initializa tion task page af ter def ormation. •Selec t Continue with C urrent Data to sp ecify tha t the solution v ariables r emain the v alues obtained in the pr evious design stage .This selec tion will r educ e the numb er of it erations needed t o reach convergenc e compar ed t o the Initializ e Data A fter M orphing selec tion. Note tha t if the solv er di- verges dur ing an in termedia te design stage , the solution v ariables will b e initializ ed and the solution will b e attempt ed again. •Selec t Read D ata F ile A fter M orphing to sp ecify tha t the solution v ariables ar e set t o the v alues obtained fr om the da ta file sp ecified in the Data F ile N ame text-en try box.This selec tion will r educ e the numb er of it erations needed t o reach c onvergenc e compar ed t o Initializ e Data A fter M orphing selec tion or (in c ases wher e the solution div erges f or an in termedia te design stage) the Continue with C urrent Data selec tion. Note tha t this selec tion is not a vailable when newuoa is selec ted fr om the Optimiz er drop-do wn list. h.If you did not selec t the newuoa optimiz er, you ha ve the option of sp ecifying c ommands tha t will b e execut ed dur ing the optimiza tion r uns of the mesh mor pher/optimiz er, via the t ext-en try boxes in the Execut e Commands group b ox. A command c an b e a t ext command or the name of a c ommand macr o you ha ve defined (or will define), as descr ibed in Defining M acros (p.2662 ).You c an also en ter a ser ies of text commands and/or macr os, as long as the y are separ ated b y a semi-c olon (;). During optimiza tion r uns, def ormation o ccurs as par t of e very design it eration. You decide the specific p oint dur ing the design it eration tha t the c ommand is e xecut ed: •If you w ant a c ommand t o be execut ed af ter the design has b een mo dified , but b efore ANSY S Fluen t has star ted t o run the c alcula tion f or tha t design stage , enter the c ommand in the Initial Commands text-en try box.There ar e no r estrictions on the c ommands tha t can b e en tered: you c an en ter commands tha t read sa ved da ta, perform FMG initializa tion, execut e an en tirely indep enden t on-demand UDF , or e ven c all a Scheme r outine . •If you w ant a c ommand t o be execut ed af ter the solution has r un and c onverged f or a design stage , enter the c ommand in the End C ommands text-en try box.There ar e no r estrictions on the c ommands tha t can b e en tered. Examples ar e commands f or p ostpr ocessing solution variables , monit oring c ontours and v ectors of diff erent variables , tak ing snapshots of each design change , and so on, at every design stage . Imp ortant If the c ommand t o be execut ed in volves sa ving a file , see Saving F iles D uring the C alcula tion (p.2664 ) for imp ortant gener al inf ormation. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3204Design A naly sis and Optimiza tionAs not ed in Automa tic N umb ering of F iles (p.585), the sp ecial char acter,%i, can be used t o cr eate unique filenames b y including the it eration numb er. However, by default , the solution will b e initializ ed af ter each mesh def ormation and the iteration c oun t restar ted.Therefore, the r esulting filename c annot b e used t o iden tify which design stage pr oduced it (tha t is, the first design stage ma y con- verge a t 50 it erations , and then the sec ond design stage ma y converge a t 43 it- erations). The time tha t the file w as cr eated is a b etter w ay to iden tify wher e in the ser ies of design stages the file w as gener ated. In addition, some files ma y be overwritten if t wo design stages c onverge in the same numb er of it erations . Al- ternatively, if y ou ha ve selec ted Continue with C urrent Data under Initializa tion when setting up the optimiz er, then the it eration c oun t will not r eset and no duplic ate filenames will o ccur . i.If you did not selec t the newuoa optimiz er, you c an plot and/or r ecord the optimiza tion hist ory (tha t is, how the v alue of the objec tive func tion v aries with each design stage). Click the Monit or... butt on to op en the Optimiza tion Hist ory M onit or dialo g box (Figur e 44.39: The Optimiza tion Hist ory Monit or Dialog Box (p.3205 )) and p erform the st eps tha t follow. Figur e 44.39: The Optimiza tion Hist ory M onit or D ialo g Box i.Enable the Plot option if y ou w ant to displa y a plot of the optimiza tion hist ory in the gr aphics windo w indic ated in the Windo w numb er-en try box. Note tha t if y ou w ant to obser ve the mesh deformations dur ing the optimiza tion pr ocess, you must mak e sur e tha t Windo w is not set t o the ID of the gr aphics windo w tha t is displa ying the mesh. ii.Enable the Write option if y ou w ant to sa ve the optimiza tion hist ory da ta in a file , and sp ecify the File N ame . Note tha t you c an displa y a plot of the optimiza tion hist ory da ta gener ated dur ing the last c al- cula tion, even if the Plot or the Write options w ere not enabled dur ing the c alcula tion, as long as y ou ha ve not disc arded the da ta using the Clear butt on. Simply click the Plot butt on and the plot will b e displa yed in the ac tive gr aphics windo w. j.Click the Apply butt on t o sa ve your optimiz er settings . k.Click the Summar y butt on t o displa y a summar y of the mesh mor pher/optimiz er settings in the c onsole . 3205Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Using the M esh M orpher/Optimiz erl.Click the Optimiz e butt on t o initia te the optimiza tion pr ocess. Information ab out each r un (tha t is, each design mo dific ation) tha t is gener ated as par t of the pr oduc tion of a design stage will b e displa yed in the c onsole , and the def ormed mesh f or each r un will b e up dated in the gr aphics windo w. If you set up the sa ving of in termedia te case and da ta files in st ep 12.f and y our solution is in ter- rupted dur ing the optimiza tion r un, you c an r estar t the c alcula tion using the la test in termedia te files . Note tha t you should not r evise the def ormation r egions or c onstr aint settings f or the r e- started mesh. 13.If you w ant to use D esign Explor ation in ANSY S Workbench t o explor e multiple def ormation sc enar ios, define the optimiz er settings . a.Click the Optimiz er tab ( Figur e 44.37: The Optimiz er Tab of the M esh M orpher/Optimiz er D ialog Box (p.3201 )). b.Selec t workbench from the Optimiz er drop-do wn list. Note tha t workbench is only a vailable if y ou have launched y our ANSY S Fluen t session fr om ANSY S Workbench. c.If nec essar y, revise the default settings in the Mesh Q ualit y group b ox, as descr ibed in st ep 12.e . Note that the design p oint asso ciated with a p oor qualit y mesh will not b e up dated in Workbench. 14.Click OK to close the Mesh M orpher/Optimiza tion dialo g box. 15.If you w ant to use D esign Explor ation in ANSY S Workbench t o explor e multiple def ormation sc enar ios, save your c ase file and close y our ANSY S Fluen t session. You c an then pr oceed t o ANSY S Workbench and define the design p oints tha t will pr ovide the multiple v alues f or the input par amet ers y ou cr eated / assigned in st ep 7.c . For mor e inf ormation ab out using design p oints to explor e ANSY S Fluen t results , see Working With Input and Output P aramet ers in Workbench in the ANSY S Fluen t in Workbench U ser's G uide . 16.If you manually def ormed the mesh or used the built-in optimiz ers, run y our c ase file with the def ormed mesh. 17.If you w ant to rerun a c ase file in which the mesh has b een def ormed b y the Optimiz e butt on in the Op- timiz er tab , you should not r evise the def ormation r egions or c onstr aint settings f or the def ormed mesh. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3206Design A naly sis and Optimiza tionChapt er 45: Performing S ystem C oupling S imula tions U sing F luen t You c an use System C oupling to perform coupled simula tions tha t involve multiple ph ysics solv ers, coupling ac tive co-simula tion par ticipan ts and/or imp orting sta tic da ta fr om an e xternal da ta sour ce. For e xample , you c an r un ANSY S M echanic al and ANSY S Fluen t) in a single analy sis and/or imp ort da ta from an output file in to an ANSY S Fluen t analy sis. System C oupling c an b e used in t wo diff erent contexts: •System C oupling in ANSY S Workbench : System C oupling is r un fr om the Workbench in terface. •Command-Line S ystem C oupling: System C oupling is r un fr om the c ommand line . Note For S ystem C oupling c ases using F luen t, it is a b est pr actice to run F luen t in double pr ecision. Additional inf ormation c an b e found in the f ollowing sec tions: 45.1. Performing S ystem C oupling in ANSY S Workbench 45.2. Performing C ommand Line S ystem C oupling 45.3. Supp orted C apabilities and Limita tions 45.4. Variables A vailable f or System C oupling 45.5. System C oupling R elated S ettings in F luen t 45.6. FSI S etup R ecommenda tions f or Fluen t-Mechanic al Couplings 45.7. How Fluen t’s Execution is A ffected b y System C ouplings 45.8. Restar ting F luen t Analy ses as P art of S ystem C ouplings 45.9. System C oupling c ase with F luen t using P atched D ata 45.10. Running F luen t as a S ystem C oupling P articipan t from the C ommand Line 45.11. Troublesho oting Two-W ay Coupled A naly sis P roblems 45.12. Product Lic ensing C onsider ations when using S ystem C oupling 45.1. Performing S ystem C oupling in ANSY S Workbench You c an p erform sy stem c oupling in Workbench b y connec ting a S ystem C oupling c omp onen t system to your M echanic al sy stem and t o your ANSY S Fluen t fluid flo w analy sis sy stem. The f ollowing is the list of supp orted c oupling par ticipan ts: •Fluen t •Static S tructural •Transien t Structural •Stead y-State Thermal •Transien t Thermal 3207Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.•External D ata Connec ting the Setup cell fr om an ANSY S Fluen t analy sis sy stem t o the Setup cell for the System Coupling comp onen t system signals the la tter sy stem tha t the F luen t solv er will ac t as a c o-simula tion participan t in a c oupled analy sis. Most of the c oupling r elated settings f or y our analy sis ar e made through the System C oupling system’s Setup user in terface.The f ew c oupling r elated settings tha t are requir ed in the F luen t setup ar e descr ibed b elow, in the sec tion System C oupling R elated S ettings in Fluen t (p.3215 ). Onc e the c oupling setup is c omplet e, the c oupled analy sis is e xecut ed b y up dating the System C oupling system’s Solution cell, rather than the same c ell in the c onnec ted c o-simula tion participan t systems . For mor e inf ormation, see Using S ystem C oupling in Workbench and Supp orted P articipan ts for S ystem Coupling in Workbench . Note In or der t o ha ve changes made in F luen t systems pr opaga ted t o do wnstr eam S ystem Coupling sy stems , save your pr ojec t, synchr oniz e with Workbench, or close F luen t.This will ensur e tha t the inf ormation passed t o System C oupling ma tches settings in F luen t. If this is not done , the analy sis ma y be allo wed t o run but the f ollowing Workbench sta te er ror will be issued a t the end of the r un: Update of the Solution component in System Coupling failed: Update of the Solution component in System Coupling did not mark container as updated (final state is OutOfDate). 45.2. Performing C ommand Line S ystem C oupling Command-Line S ystem C oupling pr ovides enhanc ed c ontrol o ver coupled simula tion pr ocesses , including automa tic star ts and r estar ts for par ticipan ts, the abilit y to manipula te the S ystem C oupling da ta mo del via c ommand line , and an in teractive solution w orkflow. In this c ontext, you c an still set up par ticipan t physics in the par ticipan t's user in terface, but y ou'll p erform the c oupled analy sis —star ting the c oupling service, loading par ticipan ts, specifying v alues f or c oupling-r elated analy sis settings , and aut oma tically starting par ticipan ts— using the c ommand line . Note If you don't w ant to use a fully aut oma tic c oupling w orkflow, you still ha ve the abilit y to run one or mor e par ticipan ts manually . The the c ommand-line S ystem C oupling w orkflow requir es a S ystem C oupling par ticipan t file (.scp ) written b y Fluen t, as descr ibed in Gener ating a S ystem C oupling F ile (p.3209 ). Onc e the ph ysics and S ystem C oupling setups ar e complet e, the c oupled analy sis is e xecut ed and managed b y the S ystem C oupling S ervice. For mor e inf ormation, see Using C ommand-Line S ystem C oupling . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3208Performing S ystem C oupling S imula tions U sing F luen t45.2.1. Gener ating a S ystem C oupling F ile To utiliz e command-line S ystem C oupling , you must gener ate a S ystem C oupling par ticipan t (.scp ) file. You c an wr ite a .scp file a t an y time e ven if y ou ha ve not sp ecified an y System C oupling inf ormation by selec ting the Write SCP F ile... ribbon tab it em t o op en the Selec t File dialo g box. File → Export → System C oupling ... → Write SCP F ile... Enter the name of S ystem C oupling par ticipan t file and click OK. You also ha ve the option of aut oma tically wr iting all a vailable sur face and v olume inf ormation tha t could b e used in a S ystem C oupling r un an y time y ou wr ite a c ase file . You c an enable this a t an y time b y selec ting the Auto-wr ite SCP F ile... ribbon tab it em. File → Export → System C oupling ... → Auto-wr ite SCP F ile... On the dialo g box tha t app ears , selec t Auto-wr ite SCP F ile with C ase F ile and click OK. Afterwards, any time y ou wr ite a c ase file , a .scp file will also b e wr itten. 45.3. Supp orted C apabilities and Limita tions ANSY S Fluen t supp orts the f ollowing c apabilities when used in a S ystem C oupling analy sis: •Force and displac emen t da ta tr ansf ers on w all b oundar ies (including w alls in sliding mesh z ones), porous jump b oundar ies, and p orous z one in terfaces: –Input of incr emen tal displac emen ts da ta fr om S ystem C oupling allo w mo ving and def orming mesh specific ation on b oundar y wall regions (including w alls in sliding mesh z ones), porous jump b ound- aries, and p orous z one in terfaces (via a z ero-thick ness p orous jump b oundar y). Note the additional System C oupling option in the Dynamic M esh Z ones dialo g box; see Specifying the M otion of D y- namic Z ones (p.1345 ) for mor e inf ormation. –Output of f orce da ta on b oundar y wall regions (including w alls in sliding mesh z ones), porous jump boundar ies, and p orous z one in terfaces (via a z ero-thick ness p orous jump b oundar y). Fluen t is able to ser ve the t otal f orce variable (visc ous and nor mal) on all w all b oundar ies (with or without enabling the System C oupling option in the Dynamic M esh Z ones dialo g box). See Variables A vailable f or System C oupling (p.3211 ) for details ab out the f orces tr ansf erred fr om the w all and p orous jump boundar ies. •Thermal da ta tr ansf ers on w all b oundar ies and c ell z ones: –Input of t emp erature da ta and hea t flo w da ta fr om S ystem C oupling on all w all b oundar ies. Note the additional via S ystem C oupling option in the Thermal tab of the Boundar y Conditions dialo g box. –Input of hea t rate da ta fr om S ystem C oupling on c ell z ones . 3209Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Supp orted C apabilities and Limita tions–Output of t emp erature da ta, hea t flo w da ta, and hea t transf er coefficien t da ta to System C oupling on all w all b oundar ies (with or without enabling the System C oupling option in the Dynamic M esh Zones dialo g box). –Output of t emp erature da ta to System C oupling fr om c ell z ones . •Data tr ansf ers fr om w all b oundar ies tha t are in F luen t sliding mesh z one or r igid b ody zone . •The use of tr iangular and quadr ilateral fac ed in terface cell types. •Full d ynamic mesh supp ort everywher e except on c oupling in terface. •Full supp ort for lo cal and distr ibut ed par allel solv er execution. •Convergenc e da ta for all equa tions (f or e xample , continuit y, momen tum, and ener gy convergenc e data) is shar ed with the sy stem c oupling ser vice at run time . Monit or da ta is shar ed if the monit or p oint has an it eration fr equenc y set. If the monit or p oint has a time st ep fr equenc y set , monit or da ta will not be shar ed with S ystem C oupling . In Workbench, this da ta fr om F luen t can b e char ted in c onjunc tion with other da ta in the system coupling char t at all a vailable in tervals. Intermedia te da ta p oints ar e not ar tificially cr eated in the sy stem c oupling char t. Monit or da ta can also b e plott ed in F luen t Solution M onit oring. Note the f ollowing limita tions when using F luen t in a S ystem C oupling analy sis: •Using S ystem C oupling with the R emot e Solver M anager (RSM) in F luen t is not supp orted. If attempt ed, you will r eceive the f ollowing message: Solution updates for Fluent systems participating in System Couplings must run in the foreground. This change has been automatically applied. •When using a w all and w all-shado w pair in F luen t as S ystem C oupling in terfaces, you'll need t o create a duplic ate sur face in M echanic al.These will b e pair ed with t wo sets of shell elemen ts in M echanic al. For mor e inf ormation, see Coupling with Wall/W all-S hado w Pairs or Thin Sur faces in the Mechanic al User's G uide . •Fluen t must use a 3D mesh, with da ta tr ansf er regions c onsisting of elemen t fac es within the 3D mesh. Data Transf er regions c annot e xist in 2D meshes (wher e the da ta tr ansf er region w ould b e a line/cur ve). •Data tr ansf er regions on the c oupling in terface cannot c ontain hanging no des (which r esult fr om hanging no de adaption and ma y occur in some C utCell meshes). •The mesh t opology on a S ystem C oupling b oundar y in F luen t must r emain fix ed f or the dur ation of the analy sis.This means tha t dynamic r emeshing c annot b e used on the S ystem C oupling b oundar y, but in terior no des a way from the S ystem C oupling b oundar y can still b e remeshed dur ing the solution. •To transf er forces on w all and w all-shado w pair , you need t wo sur faces in M echanic al to ma tch the t wo surfaces in F luen t. In this c ase, you c annot use a single set of shell elemen ts in M echanic al. An example of a w all and w all-shado w pair is t wo diff erent fluids on either side of a z ero-thick ness in ternal w all in Fluen t. •The non-it erative time-ad vancemen t (NIT A) scheme in F luen t cannot b e used in a S ystem C oupling analy sis. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3210Performing S ystem C oupling S imula tions U sing F luen t•When e xecuting design p oints for S ystem C oupling c ases wher e Fluen t is a par ticipan t,Program Controlled should not b e used f or F luen t Initializa tion M etho d. •Shell c onduc tion is not a vailable when the F luen t region is set up t o receive ther mal da ta via S ystem Coupling . 45.4. Variables A vailable f or S ystem C oupling The f ollowing v ariables will b e available on all b oundar y wall regions . Table 45.1: Variables On B oundar y Wall Regions Physical TypeData Type Transf er DirectionDispla y Name / In ternal N ame Force VectorXYZ* Output force / force Length VectorXYZ* Input displac emen t / displacement Temp erature Scalar Input and Outputtemp erature / temperature Heat Rate Scalar Input and Outputhea t flo w / heatflow Heat Transf er Coefficien tScalar Output hea t transf er c oefficien t / heat- transfer-coefficient Temp erature Scalar Output near w all t emp erature / near- wall-temperature The f ollowing v ariables will b e available on all c ell z one r egions . Table 45.2: Variables On C ell Z one Regions Physical TypeData Type Transf er DirectionDispla y Name / In ternal N ame Heat Rate Scalar Input hea t rate / heatrate Temp erature Scaler Output temp erature / temperature The f ollowing v ariables will b e available on all p orous jump b oundar ies. Table 45.3: Variables On P orous Jump B oundar y Physical TypeData Type Transf er DirectionDispla y Name / In ternal N ame Force VectorXYZ* Output force / force Length VectorXYZ* Input displac emen t / displacement *Represen ts the f orce vector ( , , ) and the displac emen ts vector ( , , ) respectively. 3211Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Variables A vailable f or System C ouplingFor inf ormation on the da ta tr ansf ers supp orted b y System C oupling f or each par ticipan t in each coupling c ontext, see the tables in System C oupling C apabilities . 45.4.1. Force transf erred t o System C oupling fr om a Wall B oundar y The f orce vector sen t from each w all b oundar y in F luen t to System C oupling is giv en b y: (45.1) wher e • is the gauge pr essur e in F luen t. • is the pr essur e rise due t o Floating Op erating P ressur e if enabled (f or details , see Floating Op erating Pressur e (p.1221 )). • is the Referenc e Pressur e, which diff ers fr om the Operating P ressur e (for details , see Reference Values (p.2952 )). If the Referenc e Pressur e is set t o zero, then gauge pr essur e forces will b e sen t to System Coupling . If it is set t o the nega tive of the op erating pr essur e, then absolut e pr essur e forces will b e sen t to System C oupling . • is the fac e area v ector. • is the f orce vector due t o visc ous f orces. • is the f orce vector due t o par ticle f orces. Note If buo yancy is ac tive, the h ydrosta tic pr essur e force due t o a nonz ero op erating densit y is excluded fr om the f orce calcula tion. To include this c ontribution, the op erating densit y must b e set t o 0. For mor e inf ormation on f orce calcula tions , see Computing F orces, Momen ts, and the C enter of P ressur e in the Fluent Theor y Guide . 45.4.2. Force transf erred t o System C oupling fr om a P orous Jump B oundar y When a p orous jump b oundar y is selec ted as a sour ce region f or a sy stem c oupling analy sis, the f orces transf erred fr om this p orous jump b oundar y are calcula ted diff erently dep ending on if the p orous jump is b etween fluid r egions , or b etween a fluid r egion and a p orous z one . •When the p orous jump separ ates two fluid z ones , or f orms an in terior r egion in a fluid z one: The f orce transf erred t o System C oupling is the net f orce acr oss the jump .The thick ness and coefficien t par amet ers defined f or the p orous jump ar e used t o calcula te the pr essur e dr op across the jump .This pr essur e dr op is c onverted t o a f orce vector tha t is tr ansf erred t o System Coupling .This f orce do es not include an y visc ous f orces. •When the p orous jump separ ates a p orous z one and a fluid z one: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3212Performing S ystem C oupling S imula tions U sing F luen tThis c ase will o ccur if the upstr eam or do wnstr eam fluid-p orous in terface is changed t o a p orous jump .The p orous jump is used t o allo w a c onnec tion b etween the upstr eam and do wnstr eam porous z one in terface and S ystem C oupling , sinc e the p orous z one in terface regions c annot connec t dir ectly t o System C oupling . The fac e pr essur e on the p orous jump is c onverted t o a f orce vector and tr ansf erred t o System Coupling . A p ositiv e fac e pr essur e will pr oduce a f orce vector tha t alw ays points in to the p orous zone .The f orce calcula ted do es not include an y visc ous f orces. It is b est t o assign z ero-thick ness t o the p orous jump so tha t ther e is no pr essur e dr op acr oss the jump . Note tha t volumetr ic forces in the p orous z one ar e not passed t o System C oupling . This c ase is in tended t o mo del thin p orous z ones wher e the def ormation of the z one c an b e appr oxima ted b y consider ing only the fluid pr essur e on the upstr eam and do wnstr eam p orous interfaces. If a nonz ero thick ness is assigned t o a p orous jump tha t is adjac ent to a p orous z one , then ther e will b e a pr essur e dr op acr oss the p orous jump .The f orce transf erred t o sy stem c oupling is calcula ted using the fac e pr essur e on the upstr eam side of the p orous jump , before the pressur e dr op acr oss the jump has b een applied . See the image b elow. –Force transf erred on the upstr eam side of the p orous z one (a) will b e consist ent with the upstr eam fluid pr essur e (a). –Force transf erred on the do wnstr eam side of the p orous z one (c) will b e inc onsist ent with the do wnstr eam fluid pr essur e (d). On the do wnstr eam side of the p orous z one , the f orce transf erred t o sy stem c oupling is c onsist ent with the e xit pr essur e from the p orous z one , before the pr essur e dr op acr oss the p orous jump has b een applied .The do wnstr eam fluid pressur e is c alcula ted af ter the pr essur e dr op is applied . Figur e 45.1: Force tr ansf erred t o System C oupling when P orous Jump Thick ness is Non-Z ero For inf ormation ab out the p orous jump b oundar y condition, see Porous J ump B oundar y Condi- tions (p.1016 ). 3213Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Variables A vailable f or System C oupling45.4.3. Displac emen t transf erred fr om S ystem C oupling The f ollowing applies in a c oupled analy sis wher e displac emen t is r eceived b y Fluen t. •The displac emen t da ta received b y Fluen t represen ts the incr emen tal displac emen t for the cur rent time st ep (the incr emen tal displac emen t sinc e the end of the pr evious time st ep). •The displac emen t variable is only a vailable on w alls tha t ha ve the System C oupling mo ving and de- forming mesh (MDM) option selec ted, and tha t qualify as v alid c oupling r egions . •In a gener al coupled analy sis, when F luen t solv es b efore or simultaneously t o the solv er sending the displac emen t (such as M echanic al), then dur ing the first c oupling it eration of each c oupling st ep the displac emen t received is 0 [m]. 45.4.4. Displac emen t transf erred fr om S ystem C oupling t o a S liding M esh Zone When tr ansf erring da ta to or fr om a w all b oundar y in a sliding mesh z one , you must ensur e tha t the coupled par ticipan t (such as M echanic al) do es not r otate its mesh. One w ay to do this in M echanic al is to use a R otational Velocity. For mor e inf ormation ab out the R otational Velocity boundar y condition, see Rotational Velocity in the Mechanic al U ser's G uide . For inf ormation ab out sliding meshes in F luen t, see Using S liding M eshes (p.1257 ). 45.4.5. Absolut e Pressur e Example Force transf erred fr om a F luen t wall b oundar y in a S ystem C oupling analy sis is the gauge pr essur e minus the sp ecified R eference Pressur e.You c an change the f orce transf erred b y changing the R eference Pressur e value .The f ollowing e xample of a pr essur ized sub-sea pip e is a demonstr ation of ho w to transf er the absolut e pr essur e in a S ystem C oupling analy sis b y changing the R eference Pressur e. Consider flo w in a pr essur ized sub-sea pip e.The pip e is pr essur ized t o 110 bar absolut e and the e xter- ior w ater pr essur e is 100 bar .The e xterior sea w ater is not mo deled .The in ternal sur face of the pip e forms an FSI in terface to a M echanic al mo del of the pip e. In Fluen t the Op erating P ressur e would t ypic ally b e set t o 110 bar . By default the f orces passed t o System C oupling w ould only include the lo cal pr essur e changes r elative to 110 bar , which clear ly do es not r epresen t the r eal ph ysics.To include the absolut e pr essur e in the f orces sen t to System C oupling , the R eference Pressur e in F luen t should b e set t o -110 bar .The M echanic al mo del w ould then need a pressur e of 100 bar applied t o the e xterior sur faces of the pip e. Although this appr oach is v alid, it is not ideal b ecause the c orrect str uctural solution is only obtained if 100 bar of the in terior pr essur e cancels out with the 100 bar e xterior pr essur e. Relying on t wo lar ge forces to exactly c ancel out is pr one t o discr etiza tion (mesh r esolution) er rors. Minimizing the f orces sent acr oss the FSI in terface is also go od pr actice.Therefore the b est appr oach is t o use an Op erating Pressur e of 110 bar and a R eference Pressur e of -10 bar in F luen t.The f orces F luen t sends t o System Coupling ar e then based on the gauge pr essur e minus -10 bar , tha t is, the gauge pr essur e plus 10 bar . This acc oun ts for the pr essur e diff erence between the in terior and e xterior of the pip e, so ther e is no need t o apply an e xternal pr essur e in M echanic al.We ar e no longer r elying on t wo lar ge f orces c ancelling out and w e ha ve minimiz ed the f orces sen t acr oss the FSI in terface. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3214Performing S ystem C oupling S imula tions U sing F luen t45.5. System C oupling Rela ted S ettings in F luen t •Double-P recision S olver System C oupling c ases ma y benefit fr om the use of F luen t's double-pr ecision solv er. For c oupling cases with mo ving and def orming meshes (MDM), it is a b est pr actice to use F luen t's double-pr ecision solv er. For mor e inf ormation ab out F luen t's single- and double-pr ecision solv ers, see Single-P recision and D ouble-P recision S olvers in the Fluent U ser's G uide (p.38). –In the F luen t Launcher , selec t Double P recision to use F luen t’s double-pr ecision solv er. •Dynamic M esh –The System C oupling option must b e selec ted on the desir ed mo ving and def orming w all boundar ies in or der t o obtain displac emen ts fr om other c o-simula tion par ticipan ts tak ing par t in the c oupled analy sis. –Make sur e the appr opriate solution stabiliza tion options ar e selec ted in the Solver Options tab f or the System C oupling boundar y zone (and p ossibly other b oundar y zones nearb y). Solution stabiliza tion should b e ac tivated if y ou find tha t the F luen t solution is par ticular ly sensitiv e to the da ta obtained thr ough sy stem c ouplings . For e xample , it is of ten b eneficial for FSI pr oblems in which the fluid is inc ompr essible . •Heat Transf er –The via S ystem C oupling option must b e selec ted on the desir ed w all b oundar ies in or der t o obtain heat transf er da ta (t emp erature or hea t flo w) fr om other par ticipan ts tak ing par t in the c oupled analy sis. •Run C alcula tion –When r unning as par t of a tr ansien t coupled analy sis, the st ep siz e for and dur ation of the analy sis ar e controlled b y the S ystem C oupling ser vice. →The Time S tep S ize specified in the F luen t setup is cur rently ignor ed; the F luen t solution will b e ad vanced using the time st ep siz e sp ecified as par t of the S ystem C oupling setup . →The Numb er of Time S teps is also ignor ed. –The sp ecified Max I terations/T ime S tep corresponds t o the maximum numb er of nonlinear solv er it erations performed p er coupling it eration. For st eady-sta te, system–c oupled F luen t analy ses, the numb er of it erations sp ecified in F luen t is equal to the maximum numb er of solv er it erations solv ed p er coupling it eration in a c oupling st ep. Prior t o ANSY S FL UENT 14.5, the numb er of it erations sp ecified in F luen t was equal t o the solv er it erations solv ed in a c oupling st ep and w as divided equally b etween the c oupling it erations in a c oupling st ep. You c an r ecover the pr evious b ehavior b y using the f ollowing c ommand:(rpsetvar ’sc/steady/default-iteration-method? #f) . For pseudo-tr ansien t cases , refer to Performing P seudo Transien t Calcula tions (p.2617 ) in the Fluen t User's Guide (p.1). For st eady-sta te dynamic mesh applic ations , refer to Steady-State Dynamic M esh A pplic ations (p.1370 ) in the Fluen t User's G uide (p.1). 3215Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.System C oupling R elated S ettings in F luen t45.6. FSI S etup Rec ommenda tions f or F luen t-M echanic al C ouplings The f ollowing ar e best pr actices for FSI (fluid-str ucture in teraction) c ases in volving F luen t and M echan- ical: 45.6.1. Using C ontact Detection f or Fluen t-Mechanic al FSI P roblems 45.6.2. Recommenda tions f or D ynamic M esh S ettings f or Fluen t-Mechanic al FSI 45.6.3. Patholo gies & C andida te Resolutions f or Fluen t-Mechanic al FSI 45.6.1. Using C ontact Detection f or F luen t-M echanic al FSI P roblems In gener al terms, contact det ection det ermines wher e the c omput ed mesh motion will r esult in c ontact of a mo ving sur face with other sur rounding sur faces. However, the M echanic al and F luen t solv ers each define it a bit diff erently. For M echanic al, it refers t o sur faces/b odies c oming in to ph ysical contact, while f or F luen t, it refers t o wha t Fluen t do es when t wo sur faces c ome in to close pr oximit y (i.e ., flow blockage). Contact det ection is of ten used in FSI simula tions r equir ing flo w blo ckage – i.e ., cases f or which y ou need t o restrict the flo w or limit the mo vemen t between b oundar ies – such as v alve applic ations with highly fle xible flo w-control geometr y. Using the same geometr y, you c an apply an off set t o both the fluid and str uctural sides of the analy sis.The off set applied in F luen t sp ecifies a t oler ance within which cells ar e flagged f or the applic ation of flo w resistanc e, while the off set sp ecified in M echanic al (as de- scribed in Geometr ic M odific ation in the Mechanic al U ser's G uide ) restricts the mo ving b oundar y by a certain distanc e from a sur rounding sur face, so tha t a flo w restriction c an b e applied in tha t cavity. This also pr events the fluid mesh fr om f olding if the mesh is pinched b etween the mo ving b oundar y and a sur rounding sur face.The off set applied t o the str uctural side is in tended t o mir ror the mo vemen t restriction applied on the fluid side , so tha t both b odies ar e aligned dur ing c oupling .This simplifies the pr ocess b ecause no mo dific ation t o the geometr y or mesh is r equir ed. The r ecommended sequenc e for setting up c ontact det ection in a c oupled FSI pr oblem b etween a Fluen t-Mechanic al coupling is summar ized b elow: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3216Performing S ystem C oupling S imula tions U sing F luen t1.Set up c ontact det ection in the F luen t solv er. a.Iden tify the distanc e tha t will b e requir ed t o blo ck off the flo w. (To do this , you ma y need t o run one- way FSI analy sis t o test ho w close the mo ving b oundar y can get t o sur rounding sur faces without causing the mesh t o fold.) b.Using the obtained distanc e, set the c ontact det ection t oler ance — i.e ., a pr oximit y thr eshold t o det ect when the mo ving b oundar y is within a sp ecified t oler ance of the sur rounding sur face. c.Apply visc ous or p orous r esistanc e to restrict the flo w between the off set, using the flo w-control settings provided b y the F luen t solv er. For mor e inf ormation, see Contact Detection S ettings (p.1334 ). 2.Set up c ontact det ection in the M echanic al solv er. In the str uctural solv er, configur e contact det ection settings t o ma tch those of the F luen t solv er. For mor e inf ormation, see Geometr ic M odific ation in the Mechanic al U ser's G uide . 3217Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.FSI S etup R ecommenda tions f or Fluen t-Mechanic al Couplings45.6.2. Rec ommenda tions f or D ynamic M esh S ettings f or F luen t-M echanic al FSI Smoothing •Diffusion-based smo othing is gener ally r ecommended , using the b oundar y distanc e diffusion func tion. •A diffusion par amet er (α) = 1.5 is a go od star ting p oint, as it w orks w ell for absorbing the motion with the far field mesh. •If the b oundar y layer mesh def orms, incr easing the diffusion par amet er can fur ther pr eser ve the mesh close t o the mo ving b oundar y. •If remeshing is not r equir ed Smoothing F rom Ref erenc e Position should b e selec ted, specific ally f or periodic motion. Remeshing •Recommended star ting p oint for the r emeshing minimum (Lmin) and maximum length sc ales (Lmax) ar e 0.4Lmin and 1.4Lmax. –Global length sc ales c an b e set thr ough: Dynamic M esh > S ettings > R emeshing > P aramet ers. –Global length sc ales of the mesh c an b e found in M esh Sc ale Inf o. –Local length sc ales c an b e found f or each D ynamic M esh Z one under the M eshing Options tab •Remeshing and smo othing should b e enabled lo cally f or all D ynamic M esh Z ones tha t are of t ype Deforming , this allo ws remeshing and smo othing t o be applied t o fac es adjac ent to the S ystem C oupling R egion. –In addition, both Region and Local should b e selec ted f or R emeshing M etho ds. Region allo ws remeshing based on length sc ales while L ocal allo ws for remeshing based on sk ewness . It is imp ortant to not e tha t remeshing will not o ccur if L ocal is not selec ted. It is also imp ortant to rememb er tha t ther e is no dir ect control o ver sk ewness and siz e cr iteria of the remeshed c ells.Therefore, you c an only indir ectly c ontrol these cr iteria of the def ormed mesh. For tha t reason, if the r emeshed c ells ar e not of adequa te qualit y, the user c an fur ther tigh ten the r elated cr i- teria. 45.6.3. Patholo gies & C andida te Resolutions f or F luen t-M echanic al FSI Troublesho oting inf ormation is a vailable on the f ollowing t opics: 45.6.3.1. Mesh F olds within the F irst C oupling S teps 45.6.3.2. Deformed P rism La yers 45.6.3.3. Interior E lemen ts ha ve High S kewness or A re Too Lar ge/small 45.6.3.1. Mesh F olds within the F irst C oupling St eps 1.Iden tify wher e the mesh f olding is o ccur ring. Open c ase file f or the f olded mesh and e xamine the C ell Volume c ontour f or the domain. You c an highligh t the f olded c ells b y setting the maximum r ange t o 0, so tha t only c ells with a nega tive volume ar e displa yed.This c an giv e an indic ation of wha t migh t be causing the mesh f olding — Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3218Performing S ystem C oupling S imula tions U sing F luen ti.e., the time st ep siz e migh t be too lar ge, or the d ynamic z ones ma y be set up inc orrectly. For information on ho w to addr ess c ases wher e the pr ism la yer is f olding , see Deformed P rism La yers (p.3219 ). 2.Rerun the c ase with smo othing and r emeshing v erbosity tur ned on. This ma y pr ovide clues as t o wha t is causing mesh f olding . a.To tur n on v erbosity for smo othing , enter the f ollowing c ommand in to the F luen t TUI: /define/dynamic-mesh/controls/smoothing-parameters/verbosity 1 b.To tur n on v erbosity for remeshing , enter the f ollowing c ommand in to the F luen t TUI: (rpsetvar 'dynamesh/remesh/verbosity 1) Note If remeshing is not tr igger ed, verify tha t the Dynamic M esh Z ones and length sc ales ar e set up c orrectly 1.Open the c ase file f or the f olded mesh. 2.Check the minimum and maximum length sc ales f or the mesh and c ompar e these t o the remeshing v alues . 3.If needed: •Tighten the length sc ales and sk ewness fac tors. •Increase the Size Remeshing In terval value . 45.6.3.2. Deformed P rism L ayers A def ormed pr ism la yer can quick ly cause a c ase t o fail due t o the mesh f olding . Fluen t cur rently do es not supp ort the r emeshing of pr ism la yers. If a c ase e xhibits def ormation in the b oundar y layer due to lar ge mo vemen t/def ormation of the FSI r egions , ther e ar e thr ee main r ecommenda tions tha t de- pending on the c ase c an r esolv e this pa tholo gy: 1.Increase the Diffusion P aramet er to incr ease the mesh stiffness ar ound the b oundar ies and c ause r egions away from the mo ving b oundar y to absorb mor e of the motion. 2.If the pr ism la yer mesh ar ound the mo ving b ody is unif orm (i.e . constan t numb er of pr ism mesh la yers around the geometr y), it is r ecommended t o split the b oundar y layer mesh in to a separ ate Cell Z one . 3.If the pr ism la yer is not unif orm (i.e . stair st epping due t o small gaps) and/or c ontact det ection is r equir ed in Fluen t, the use of o verset meshing is r ecommended . Overset meshing is also r ecommended f or comple x topologies . 45.6.3.2.1. Using B oundar y Layer Smo othing and R egion F ace Remeshing For c ases tha t exhibit pr ism la yer def ormation/shear ing, i.e. due t o transla tional mo vemen t between two bodies in close pr oximit y as sho wn in Figur e 45.2: Skewed pr ism c ells due t o transla tional motion 3219Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.FSI S etup R ecommenda tions f or Fluen t-Mechanic al Couplingsbetween t wo bodies in close pr oximit y (p.3220 ) below; boundar y Boundar y La yer S moothing M eth- od (p.1282 ) can b e implemen ted along with Region F ace M eshing . Boundar y La yer S moothing pr e- serves the b oundar y layer b y applying the displac emen t vectors on the c oupled fac e zone t o the nodes of each c ell in the b oundar y layer zone .This r equir es tha t the b oundar y layer mesh is split into a separ ate zone . As an e xample , we will go thr ough the pr ocedur e of splitting the b oundar y layer mesh f or the geometr y sho wn b elow (Figur e 45.3: Example geometr y (p.3220 )). As the geometr y includes a pr ism la yer mesh on the outside w alls as w ell as the inside w alls, the y will need t o be separ ated individually . It is imp ortant to not e tha t Boundar y La yer S moothing is only applic able when using S pring-based S moothing . Figur e 45.2: Skewed pr ism c ells due t o tr ansla tional motion b etween t wo bodies in close proximit y Figur e 45.3: Example geometr y Split the pr ism la yer cap t o a separ ate cell z one c ondition t o allo w Region F ace remeshing t o be in- voked: 1.Create a B oundar y Cell R egist er with the r equir ed pr ism elemen ts. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3220Performing S ystem C oupling S imula tions U sing F luen ta.Right click Solution >Cell Regist ers>New>Boundar y b.Use C ell D istanc e and highligh t the b oundar y zone w ere the pr ism la yers ar e located.The numb er of cells is set based on the numb er of pr ism la yers. 2.Use the B oundar y Cell R egist er to separ ate the pr ism la yers in to a separ ate cell z one . a.Click Zones > Separ ate > Cells. b.Selec t the r egist er with the pr ism c ells and the z one tha t you’d lik e to split. 3.Verify tha t the c orrect cell z ones w ere created based on the c ell regist ers and z ones . In this c ase w e ha ve split our single c ell z one in to thr ee separ ate cell z ones .The first c ell z one contains the inner b oundar y layer mesh ( Figur e 45.4: Cell Z one c ontaining the inner b oundar y layer mesh (p.3221 )), the sec ond c ell z one c ontains the out er b oundar y layer mesh ( Figur e 45.5: Cell Zone c ontaining the out er b oundar y layer mesh (p.3222 )) and finally the thir d cell z one c ontains the in terior mesh ( Figur e 45.4: Cell Z one c ontaining the inner b oundar y layer mesh (p.3221 )). Figur e 45.4: Cell Z one c ontaining the inner b oundar y la yer mesh 3221Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.FSI S etup R ecommenda tions f or Fluen t-Mechanic al CouplingsFigur e 45.5: Cell Z one c ontaining the out er b oundar y la yer mesh Figur e 45.6: Cell Z one c ontaining the in terior mesh 4.For the D ynamic M eshing settings , selec t Spring based smo othing as all other smo othing metho ds do not supp ort Boundar y La yer Smoothing ( Deform A djac ent Boundar y Layer with Z one ) will not b e available . 5.Turn on Region F ace remeshing . 6.Turn off smo othing f or the symmetr y/wall regions .This pr events cells adjac ent to mo ving w all fr om getting t oo str etched . Smoothing w ould still b e conduc ted in the in terior c ells. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3222Performing S ystem C oupling S imula tions U sing F luen t7.In the D ynamic M esh Z ones , set the mo ving pr ism la yer cell z one as a rigid b ody: a.By default , Rigid B ody Dynamic M esh Z ones r equir e a UDF t o sp ecify the mesh motion. Since the motion is pr ovided b y System C oupling , assign a “dumm y UDF ." b.The dumm y UDF is an empt y UDF , as f ollows: #include "udf.h" DEFINE_GRID_MOTION(dummy_motion, domain, dt, time, dtime) { return; } 8.For the b oundar y layer mesh t o mo ve with the C oupled r egion, Deform A djac ent Boundar y Layer with Z one must b e tur ned on: •Setting the Cell H eigh t in the Adjac ent Zone is not r equir ed, sinc e the pr ism la yer mesh will not b e remeshed . 9.Set the C ell Z one c ontaining the in terior mesh as Deforming , this will allo w the tr i/tet fac es and c ells (Figur e 45.7: Prism la yer mesh qualit y main tained f or lar ge def ormations (p.3223 )) to be remeshed . Running the c ase again, we can see ho w the pr ism la yer mesh is main tained using B oundar y La yer Smoothing and only the in terior c ells ar e remeshed . Figur e 45.7: Prism la yer mesh qualit y main tained f or lar ge def ormations 45.6.3.2.2. Overset Meshes As pr eviously men tioned , for c omple x topologies and/or if the pr ism la yer is not unif orm (i.e . stair stepping due t o small gaps), the use of o verset meshes is r ecommended . By allo wing the user t o have a separ ate mesh f or the back ground and the c omp onen ts, the r emeshing and smo othing paramet ers c an b e controlled f or each c omp onen t mesh. For e xample , the o verset mesh b elow (Figur e 45.8: Overset mesh gener ated using 3 separ ate meshes (p.3224 )) is cr eated using 3 separ ate 3223Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.FSI S etup R ecommenda tions f or Fluen t-Mechanic al Couplingsmeshes . A str uctured he xahedr al mesh is used f or the back ground , while a t etrahedr al mesh is used for the t wo geometr ies. Figur e 45.8: Overset mesh gener ated using 3 separ ate meshes The leading edge of the long r ectangle r otates clo ckwise , creating a small gap b etween the shor t rectangle . If a single mesh w as used f or this c ase, the pr ism la yer mesh ar ound the 2 c omp onen ts deforms and c auses the mesh t o fold.This o ccurs as the pr ism la yer mesh star ts to absorb the de- formation as the gap b etween the t wo geometr ies decr eases . By ha ving the c omp onen ts separ ately meshed , each c omp onen ts mesh absorbs the def ormation in its far field , before mapping it back t o the o verset mesh, main taining the pr ism la yer mesh qualit y (Figur e 45.9: Prism la yer mesh qualit y is main tained (p.3224 )). Figur e 45.9: Prism la yer mesh qualit y is main tained The gener al w orkflow to setup an o verset mesh c ase is as f ollows: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3224Performing S ystem C oupling S imula tions U sing F luen t1.Split and r emesh the r equir ed geometr ies. 2.Revise the time st ep siz e: •Consider the thr ee time sc ales . Note tha t the smaller timesc ale is dominan t. –Simula tion –Mesh def ormation –Overset meshing •The ideal time st ep siz e should b e chosen such tha t the r elative mesh motion do es not e xceed the length of the smallest c ell a t the o verset in terface for a giv en time st ep.The mesh length used f or calcula ting the time st ep should b e restricted t o cells in the o verset o verlap r egion. •It is imp ortant to not ha ve lar ge v ariations in mesh r esolution in the motion pa th tha t could tr igger large changes in the o verset in terface as the motion pr oceeds .The use of gr id pr iorities c an minimiz e large v ariations in the o verset in terface. 3.Choose the O verlap M inimiza tion r equir ed: •A cell-v olume-based metho d is r ecommended if the c omp onen t mesh r esolution is fine near w alls and incr eases gr adually a way from w alls and b ecomes similar in siz e to or lar ger than the back ground mesh. Enter the f ollowing c ommand in to the F luen t TUI: define/overset-interfaces/options/donor-priority-method 0 •A boundar y-distanc e-based metho d is r ecommended when o verlapping meshes ha ve unif orm and near ly iden tical resolutions .Therefore, it is most suitable when t wo walls ha ve small distanc e in between them. Enter the f ollowing c ommand in to the F luen t TUI: define/overset-interfaces/options/donor-priority-method 1 4.Create Overset in terface and initializ e solution: •The o verset mesh is cr eated dur ing initializa tion; it can b e view ed thr ough Results > Graphics > Mesh by check ing Overset under Options Refer to Diagnosing O verset In terface Issues (p.776) for mor e inf ormation. 45.6.3.3. Interior Elements ha ve High Sk ewness or A re Too Large/small For c ases wher e in terior c ells ar e sk ewed due t o transla tional and/or r otational mo vemen t (Fig- ure 45.2: Skewed pr ism c ells due t o transla tional motion b etween t wo bodies in close pr oximit y (p.3220 )) or remeshing r esulting in elemen ts tha t are too lar ge or small, ther e ar e two main r ecommenda tions that dep ending on the c ase c an r esolv e this pa tholo gy: 1.Use tigh ter cr iteria for the minimum and maximum length sc ales as w ell as skewness . In addition, decr ease the Size Remeshing In terval to 1 so tha t remeshing based on siz e is tr igger ed a t every time step. 3225Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.FSI S etup R ecommenda tions f or Fluen t-Mechanic al Couplings2.If the pr evious st ep w as not enough t o resolv e this , Enable Region F ace Remeshing . Region F ace Remeshing will not tr igger if a pr ism la yer mesh is lo cated in the same c ell z one w ere remeshing needs to occur .Thus, the user w ould need t o split the pr ism la yer mesh in to a separ ate cell z one . Refer to the Deformed P rism L ayers sec tion f or detailed instr uctions . For the c ase sho wn b elow, setting tigh ter cr iteria for the minimum and maximum length sc ales t o remesh e very time st ep w as not sufficien t to pr oduce a high-qualit y mesh in the gap ( Figur e 45.10: Ori- ginal M esh (lef t) and def ormed mesh (r ight) with smo othing and r emeshing enabled (p.3226 )). Since ther e is no dir ect control o ver sk ewness and siz e cr iteria of the r emeshed c ells, you c an only indir ectly control these cr iteria of the def ormed mesh. By using Region F ace Remeshing , this allo ws mor e control o ver the siz e of the r emeshed c ells ( Fig- ure 45.11: Original M esh (lef t) and def ormed mesh (r ight) using smo othing and R egion F ace Remeshing (p.3227 )).This is done b y splitting or deleting the c ells dir ectly adjac ent to the mo ving boundar y based on the maximum and minimum length sc ales only . But as pr eviously men tioned , the prism la yer mesh has t o be in a separ ate cell z one and tr eated as a r igid b ody. Figur e 45.10: Original M esh (lef t) and def ormed mesh (r ight) with smo othing and r emeshing enabled Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3226Performing S ystem C oupling S imula tions U sing F luen tFigur e 45.11: Original M esh (lef t) and def ormed mesh (r ight) using smo othing and Region F ace Remeshing Note •Overset meshes ar e not supp orted b y CFD-P ost. So, post pr ocessing must b e handled dir ectly in Fluen t. •For o verset meshes , volume in tegrals ar e tak en o ver all solv e cells in the domain. This r esults in double c oun ting wher e solv e cells o verlap, leading t o er rors in v olume in tegrals on o verset meshes . 45.7. How Fluen t’s Execution is A ffected b y System C ouplings ANSY S Fluen t’s execution is mo dified sligh tly t o allo w the C oupling S ervice to manage the e volution of the c oupled analy sis. For mor e inf ormation, see Process S ynchr oniza tion and A naly sis E volution . 45.8. Restar ting F luen t Analy ses as P art of S ystem C ouplings Go to the sec tion Stops and R estar ts of S ystem C oupling R uns for gener al inf ormation on r estar ting a coupled analy sis and links t o context-sp ecific inf ormation. •For System C oupling in Workbench :Restar ting a C oupled A naly sis in Workbench . •For Command-Line S ystem C oupling :Restar ting a C ommand-Line C oupled A naly sis R un. To restar t your c oupled analy sis, you will also need r estar t inf ormation sp ecific t o the par ticipan ts con- nected t o your S ystem C oupling sy stem. 3227Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Restar ting F luen t Analy ses as P art of S ystem C ouplingsFor details on other par ticipan t systems c onnec ted t o your S ystem C oupling sy stem, see the f ollowing lists of supp orted sy stems and r eferences to their c orresponding do cumen tation r egar ding r estar ts: •Supp orted P articipan ts for S ystem C oupling in Workbench •Supp orted P articipan ts for C ommand-Line S ystem C oupling 45.8.1. Gener ating F luen t Restar t Files 45.8.2. Specify a R estar t Point in F luen t 45.8.3. Making C hanges in F luen t Before Restar ting 45.8.4. Recovering the F luen t Restar t Point after a Workbench C rash 45.8.1. Gener ating F luen t Restar t Files Restar ts of a sy stem c oupling analy sis r equir es c orresponding r estar t points to exist in the c oupling service and in each of the solv ers par ticipa ting in the analy sis. Fluen t will aut oma tically gener ate the c orresponding c ase and da ta (c as/da t) files based up on r equests received fr om the S ystem C oupling ser vice. Note tha t these files ar e gener ated in addition t o the r estar t points (or r esults) manually r equest ed via the A utosave Every field in the C alcula tion A ctivities task page within F luen t. 45.8.2. Specify a Restar t Point in F luen t When the F luen t solution is up dated (or r estar ted), the c ase and da ta files (.c as and .da t) corresponding to the cur rent restar t point will b e used , if it e xists .The default r estar t point is tak en fr om the last gener ated c ase and da ta files .To sp ecify a diff erent restar t point, perform the f ollowing st eps: 1.In the Projec t Schema tic, double-click the Solution cell to op en the F luen t interface. Do not double-click the Setup cell, as this will r estore the or iginal mesh and settings . 2.Selec t the File/S olution F iles ... ribbon tab it em t o op en the Solution F iles dialo g box with a list of all available r estar t points. 3.Selec t the desir ed r estar t point. By default , the la test sa ved r estar t point is selec ted. Only one r estar t point can b e selec ted, so t o be able t o selec t a diff erent restar t point, first click the highligh ted r estar t point to deselec t it. Make sur e tha t you selec t the r estar t point tha t corresponds t o the r estar t points selec ted f or the System C oupling ser vice and the other c oupling par ticipan ts. 4.Click Read to read-in the da ta for the selec ted r estar t point. 5.Onc e the da ta is r ead, click Close to close the Solution F iles dialo g box. 6.Close F luen t by selec ting the File/C lose F luen t ribbon tab it em. 45.8.3. Making C hanges in F luen t Before Restar ting In some c ases , Fluen t setup changes ar e requir ed t o avoid failur e of the c oupled analy sis (f or e xample , changes t o iteration c ontrols, under-r elaxa tion fac tors, and so on). The settings tha t are stored in the case file c orresponding t o the cur rent restar t point will b e used f or F luen t restar ts. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3228Performing S ystem C oupling S imula tions U sing F luen tClose F luen t by selec ting the File/C lose F luen t ribbon tab it em. If you ar e pr esen ted with a notific ation that the mo dified mesh and settings will b e used f or the cur rent run, cho ose OK to acc ept and close the dialo g box. 45.8.4. Rec overing the F luen t Restar t Point after a Workbench C rash Workbench or one of the c omp onen ts ma y crash such tha t restar t files ar e available but the y are not recogniz ed or p opula ted in the Workbench pr ojec t. If this is the c ase, you will b e able t o recover y our projec t and r estar t your analy sis. See Restar ting a C oupled A naly sis in Workbench for the st eps needed t o recover a c oupled analy sis after a Workbench cr ash. You will also need the inf ormation b elow ab out F luen t, as w ell as inf ormation specific t o the other par ticipan t systems c onnec ted t o System C oupling . For other par ticipan t systems connec ted t o your S ystem C oupling sy stem, see Supp orted P articipan ts for S ystem C oupling in Work- bench for a list of supp orted sy stems and r eferences to their c orresponding do cumen tation r egar ding restar ts. The usual pr ojec t dir ectory (ProjectName _files ) contains the la test F luen t and S ystem C oupling results and r estar t points (these solv ers use the liv e pr ojec t inst ead of r unning in a t emp orary dir ectory). Note tha t the .backup directory contains the or iginal v ersion of an y files tha t ha ve been mo dified sinc e the last sa ve.These files ar e useful t o recover the last sa ved sta te, but the y are not useful f or restar ting y our analy sis. To recover F luen t’s restar t point after a Workbench cr ash: 1. Double-click the F luen t Solution cell to op en F luen t interface. 2. Selec t the File/S olution F iles ... ribbon tab it em t o op en the Solution F iles dialo g box with a list of the restar t points. 3. The Solution F iles dialo g box will not b e popula ted with the da ta files wr itten b efore Workbench cr ashed , so the c orrect restar t point must b e recovered. Selec t Rec over M issing S olution... to recover the la test case and da ta files , and t o popula te the c orresponding r estar t points in the Solution F iles a t list. 4. Now tha t the solution files list is p opula ted, selec t the desir ed r estar t point. By default , the la test sa ved r estar t point is selec ted. Only one r estar t point can b e selec ted, so t o be able t o selec t a diff erent restar t point, first click the highligh ted r estar t point to deselec t it. Make sur e tha t you selec t the r estar t point tha t corresponds t o the r estar t points selec ted f or the System C oupling ser vice and the other c oupling par ticipan ts. 5. Click Read to read-in the da ta for the selec ted r estar t point. 6. Onc e the da ta is r ead, click Close to close the Solution F iles dialo g box. 7. Close F luen t by selec ting the File/C lose F luen t ribbon tab it em. 45.9. System C oupling c ase with F luen t using P atched D ata When gener ated da ta is clear ed fr om a S ystem C oupling c ase b efore a r erun, the da ta tha t was sp ecified using F luen t’s pa tch option is also clear ed. For e xample , in the M ultiphase v olume of fluid ( VOF) c ases , 3229Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.System C oupling c ase with F luen t using P atched D atathe pa tched da ta tha t is clear ed is the v olume fr action inf ormation. Fluen t needs this pa tched da ta to be able t o solv e accur ately. See Patching Values in S elec ted C ells (p.2607 ) for mor e inf ormation ab out patched da ta. For a S ystem C oupling c ase using pa tched da ta, follow the st eps b elow. Note tha t this w orkaround will not w ork with D esign P oint up dates. 1. Before setting up y our c ase in F luen t, tell F luen t to gener ate the *.ip file so tha t if needed , you will ha ve access t o pa tched da ta.To do this: a. In Workbench, selec t Tools>Options . b.On the lef t side of the dialo g box tha t op ens, selec t Fluen t, and then check Enable G ener ation of Interpolation F ile. 2. During F luen t setup , an *.ip file will no w be wr itten af ter initializa tion of y our F luen t system. 3. If you w ant to do a r erun in Workbench, after completing a S ystem C oupling r un, you need t o Clear Gener ated D ata on the S ystem C oupling sy stem’s Solution cell. For the c ases tha t use pa tched da ta, you need t o then ha ve Fluen t read the *.ip file tha t was gener ated in y our initial setup so tha t it has the correct da ta.To do this: a. From the Projec t Schema tic, open F luen t by double-click ing F luen t’s Setup cell. b.Selec t the File/In terpolate... ribbon tab it em. In the dialo g box tha t app ears , selec t Read and In ter- polate, then click Read .... c.Browse to the *.ip file, and then click OK to add ha ve Fluen t read this file . In the Interpolate Data dialo g box, selec t Close . d.You do not need t o initializ e Fluen t after reading the *.ip file. Close F luen t and c ontinue with the rerun of y our S ystem C oupling c ase. 45.10. Running F luen t as a S ystem C oupling P articipan t from the C om- mand Line System C oupling analy ses c an b e run via the c ommand line using either S ystem C oupling c ontext.To run ANSY S Fluen t as a c oupling par ticipan t: •For S ystem C oupling in Workbench System C oupling analy ses tha t are set up in Workbench, as descr ibed in Setting U p a C oupled Analy sis in Workbench f or a C ommand-Line R un, can b e run fr om the c ommand line . –Complet e the S ystem C oupling-r elated settings in F luen t (see System C oupling R elated S ettings in Fluen t (p.3215 )) –Gener ate the c ase and da ta files needed t o star t Fluen t →Choose Write and Case & D ata from the File ribbon tab in the F luen t graphic al in terface Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3230Performing S ystem C oupling S imula tions U sing F luen t–Run the Workbench setup fr om the c ommand line , as descr ibed in Executing a C ommand-Line R un of a C oupled A naly sis S et U p in Workbench . •For C ommand-Line S ystem C oupling To both set up and r un a c oupled analy sis fr om the c ommand line , perform the st eps outlined in Setting U p a C ommand-Line C oupled A naly sis and Running a C ommand-Line C oupled A naly sis. –For inf ormation on ho w to restar t an analy sis set up and r un fr om the c ommand line , see Restar ting a Command-Line C oupled A naly sis R un. –For details on alt ernate workflows and c apabilities , see Advanced Workflows for C ommand-Line System C oupling . •Note tha t if F luen t is r un in in teractive mo de, the in terface will b e locked fr om when it r eports it has established the c onnec tion t o the c oupling ser vice un til when all other c oupling par ticipan ts do the same .This o ccurs so tha t all par ticipan ts ma y be synchr oniz ed a t the Initial S ynchr oniza tion p oint. For information ab out synchr oniza tion p oints, see Process S ynchr oniza tion and A naly sis E volution . 45.11. Troublesho oting Two-W ay Coupled A naly sis P roblems The f ollowing files , found in the F luen t run dir ectory (FFF/F luen t under a Workbench design p oint dir- ectory), ma y pr ove useful in tr oublesho oting c oupled analy sis pr oblems: •cortexerror.log :This file c ontains a hist orical summar y of all of the er rors tha t ha ve occur red during all r uns e xecut ed in the same r un dir ectory.With this in mind , ensur e tha t you ar e consider ing messages c orresponding t o the most r ecent run. An example message is: "Update-Dynamic-M esh failed . Negative cell v olume det ected." This indic ates tha t at the da te and time not ed, the mesh une xpectedly failed . •solution 1.log :This file includes inf ormation r egar ding the F luen t boundar y conditions a t which data fr om S ystem C ouplings w as/is used .This file is ne ver app ended , and so it only c ontains inf ormation from the cur rent run. •solution.trn (or other tr anscr ipt file): This file c ontains a c omplet e summar y of the cur rent/latest run's e volution. This is one of the most useful files t o det ermine wh y the c oupled analy sis failed .To gener ate extensiv e debug output dur ing the analy sis, enter the f ollowing c ommand when c ompleting the F luen t problem setup: (rpsetvar 'sc/verbosity 1) Provide all of these files when submitting a r equest f or ser vice to ANSY S personnel. 45.12. Produc t Lic ensing C onsider ations when using S ystem C oupling The lic enses needed f or F luen t as par t of a S ystem C oupling analy ses ar e list ed in the table b elow. Ad- ditional lic enses ma y be requir ed f or other par ticipan t systems in the c oupled analy sis, but no additional licenses ar e requir ed f or the S ystem C oupling infr astructure itself . The simultaneous e xecution of c oupling par ticipan ts cur rently pr ecludes the use of the lic ense shar ing feature tha t exists f or some pr oduc t licenses .The f ollowing sp ecific r equir emen ts consequen tly e xist: •Distinc t licenses ar e requir ed f or each c oupling par ticipan t. 3231Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Product Lic ensing C onsider ations when using S ystem C oupling•Licensing pr eferences should b e set t o 'U se a separ ate lic ense f or each applic ation ’ rather than 'S hare a single lic ense b etween applic ations when p ossible .' Note If you ar e running one of the ANSY S Academic M echanic al and CFD licenses (A ssociate, Resear ch, or Teaching) with a solv er lic ense tha t supp orts lic ense shar ing, then y ou will b e able t o run an FSI simula tion with a single lic ense . Table 45.4: Lic enses r equir ed f or F luen t as par t of a S ystem C oupling analy sis Academic Lic ense Requir ed Commer cial Lic ense Requir edSystem Fluen t •ANSY S Academic A ssociate Mechanic al and CFD ,•ANSY S CFD , •ANSY S Fluen t, or •ANSY S Academic A ssociate CFD , •ANSY S Fluen t Solver •ANSY S Academic R esear ch Mechanic al and CFD , •ANSY S Academic R esear ch CFD , •ANSY S Academic Teaching Mechanic al and CFD , or •ANSY S Academic Teaching CFD Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3232Performing S ystem C oupling S imula tions U sing F luen tChapt er 46: Customizing F luen t You c an use ANSY S ACT t o cr eate simula tion wizar ds tha t can b e run fr om either stand-alone F luen t or Fluen t in Workbench. For gener al A CT usage inf ormation, see the ACT D evelop er's G uide . For inf ormation on A CT usage sp ecific t o Fluen t, see ACT C ustomization G uide f or F luent . 3233Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3234Chapt er 47: Task P age Ref erenc e Guide This r eference guide pr ovides inf ormation ab out the task pages in F luen t. 47.1. Meshing Task P age 47.2. Setup Task P age 47.3. Gener al Task P age 47.4. Models Task P age 47.5. Materials Task P age 47.6. Phases 47.7. Cell Z one C onditions Task P age 47.8. Boundar y Conditions Task P age 47.9. Overset In terfaces Task P age 47.10. Dynamic M esh Task P age 47.11. Reference Values Task P age 47.12. Solution Task P age 47.13. Solution M etho ds Task P age 47.14. Solution C ontrols Task P age 47.15. Solution Initializa tion Task P age 47.16. Calcula tion A ctivities Task P age 47.17. Run C alcula tion Task P age 47.18. Results Task P age 47.19. Graphics and A nima tions Task P age 47.20. Plots Task P age 47.21. Reports Task P age 47.22. Paramet ers and C ustomiza tion Task P age 47.1. Meshing Task P age The Meshing task page in troduces y ou t o the most c ommon meshing tasks in volved in solving y our CFD simula tion using ANSY S Fluen t. 47.2. Setup Task P age The Setup task page in troduces y ou t o the main tasks in volved in setting up y our CFD simula tion using ANSY S Fluen t. 47.3. Gener al Task P age The Gener al task page allo ws you t o set v arious gener ic pr oblem settings , such as those r elated t o the mesh or the solv er. Note tha t these settings b ecome a vailable only af ter y ou r ead in a c ase or mesh file. See Reading M esh F iles (p.586) and Reading and Writing C ase F iles (p.588) for details . 3235Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Controls Mesh contains c ontrols r elating t o mesh settings . Scale... opens the Scale M esh D ialog Box (p.3238 ). Check verifies the v alidit y of the mesh. The check pr ovides v olume sta tistics , mesh t opology and p eriodic boundar y inf ormation, verification of simple x coun ters, and v erification of no de p osition with r eference to the axis f or axisymmetr ic cases . See Check ing the M esh (p.788) for details . It is r ecommended that y ou check the mesh r ight af ter r eading it int o the sol ver, in or der t o det ect any mesh tr ouble b efore you get star ted with the pr oblem setup . Rep ort Qualit y displa ys various quan tities r elated t o the qualit y of the mesh in the c onsole , such as Minimum Ortho- gonal Quality and Maximum Aspect Ratio . See Mesh Q ualit y (p.719) for details . Displa y... opens the Mesh D ispla y Dialog Box (p.3239 ). Solver contains c ontrols r elating t o solv er settings . Type contains the solution metho ds a vailable f or computing a solution f or y our mo del. See Using the S olv- er (p.2559 ) for details . Pressur e-Based enables the pr essur e-based N avier-S tokes solution algor ithm (the default). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3236Task P age R eference GuideDensit y-Based enables the densit y-based N avier-S tokes c oupled solution algor ithm. Velocity Formula tion specifies the v elocity formula tion t o be used in the c alcula tion. See Choosing the R elative or A bsolut e Velocity Formula tion (p.1232 ) for details . Absolut e enables the use of the absolut e velocity formula tion. This is the default setting . Rela tive enables the use of the r elative velocity formula tion. This option is a vailable only with the Pressur e- Based solv er. Time contains options r elated t o time dep endenc e. Stead y specifies tha t a st eady flo w is b eing solv ed. Transien t enables a time-dep enden t solution. See Performing Time-D ependen t Calcula tions (p.2626 ) for details . 2D S pac e contains options a vailable only when solving t wo-dimensional pr oblems . Planar indic ates tha t the pr oblem is t wo-dimensional. (This option is a vailable only when y ou star t the 2D version of the solv er.) Axisymmetr ic indic ates tha t the domain is axisymmetr ic ab out the axis .When Axisymmetr ic is enabled , the 2D axisymmetr ic form of the go verning equa tions is solv ed inst ead of the 2D C artesian f orm. (This option is a vailable only when y ou star t the 2D version of the solv er.) Be sur e to change the z one type of the axis of r otation t o axis , using the Boundar y Conditions Task P age (p.3479 ), as descr ibed in Changing C ell and B oundar y Zone Types (p.837). Axisymmetr ic Swirl specifies tha t the swir l comp onen t (cir cumf erential c omp onen t) of v elocity is t o be included in your axisymmetr ic mo del. You should selec t this option if y ou ar e solving swir ling flo w in an axisymmetr ic geometr y (see Swirling and R otating F lows (p.1211 ) for mor e inf ormation). Gravity enables the sp ecific ation of gr avity. Gravita tional A cceler ation sets the , , and comp onen ts of the gr avitational acc eleration v ector. (The comp onen t is a vailable only in 3D solv ers.) See Natural Convection and B uoyancy-Driven F lows (p.1476 ) for details ab out buo yancy- driven flo ws.This option app ears only when Gravity is enabled . Units ... opens the Set U nits D ialog Box (p.3242 ). For additional inf ormation, see the f ollowing sec tions: 47.3.1. Scale M esh D ialog Box 3237Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Gener al Task P age47.3.2. Mesh D ispla y Dialog Box 47.3.3. Set U nits D ialog Box 47.3.4. Define U nit D ialog Box 47.3.5. Mesh C olors D ialog Box 47.3.1. Scale M esh D ialo g Box The Scale M esh dialo g box allo ws you t o convert the mesh fr om v arious units of measur emen t to SI or to apply cust om sc ale fac tors t o the individual c oordina tes of the mesh. See Scaling the M esh (p.822) for details . Controls Domain E xtents displa ys the C artesian c oordina te extremes of the no des in the mesh. (These v alues ar e not editable; the y are pur ely inf ormational.) Xmin, Ymin, Zmin shows the minimum v alues of C artesian c oordina tes in the mesh. Xmax, Ymax, Zmax shows the maximum v alues of C artesian c oordina tes in the mesh. Scaling contains c ontrols f or converting units and setting the sc ale fac tors aut oma tically. Convert Units allows you t o use the c onversion fac tors pr ovided b y ANSY S Fluen t.Then indic ate the units used when cr eating the mesh b y selec ting the appr opriate abbr eviation f or met ers, centimet ers, millimet ers, inches , or f eet fr om the Mesh Was C reated In drop-do wn list. The Scaling F actors will aut oma tically be set t o the c orrect values (f or e xample , 0.0254 met ers/inch). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3238Task P age R eference GuideSpecify Sc aling F actors allows you t o manually sp ecify a sc ale fac tor in each of the C artesian c oordina te dir ections . Mesh Was C reated In contains a list of c ommon units of length. The Scaling F actors will aut oma tically b e set based on your selec tion. The units include c ommon SI and B ritish units such as c entimet ers (cm), millimet ers (mm), inches (in), and f eet (f t). Scaling F actors contains the fac tors applied t o the mesh in each of the C artesian c oordina te dir ections .You c an en ter values manually , or use the Mesh Was C reated In list t o set sc ale fac tors aut oma tically. X is the sc ale fac tor in the direction. Y is the sc ale fac tor in the direction. Z is the sc ale fac tor in the direction (app ears only in 3D). Scale multiplies each of the no de c oordina tes b y the sp ecified sc ale fac tors. Unscale divides each of the no de c oordina tes b y the sp ecified sc ale fac tors. View Length U nit In contains a list of c ommon units of length. The Domain E xtents will aut oma tically b e set based on y our selec tion. The units include c ommon SI and B ritish units such as c entimet ers (cm), millimet ers (mm), inches (in), and f eet (f t).The units of length in the Set U nits D ialog Box (p.3242 ) will change each time y ou change y our selec tion in the View Length U nit In drop-do wn list. 47.3.2. Mesh D ispla y Dialo g Box The Mesh D ispla y dialo g box controls the displa y of z one , sur face, and par tition b oundar y meshes . See Displa ying the M esh (p.2776 ) for details ab out the it ems b elow. You c an also acc ess the Mesh D ispla y dialo g box thr ough the Postpr ocessing ribbon tab . Postpr ocessing → Graphics → Mesh → New... 3239Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Gener al Task P ageControls Mesh N ame is the name f or a mesh displa y definition. You c an sp ecify a name or use the default name mesh-id . This c ontrol app ears only f or mesh displa y definitions . Options contains the r ender ing options descr ibed b elow.To see the eff ects of y our selec tion y ou must click the Displa y butt on. Nodes enables the displa y of no des on the selec ted sur faces. Edges enables the displa y of mesh edges on the selec ted sur faces. Faces enables the displa y of mesh fac es (filled meshes) on the selec ted sur faces. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3240Task P age R eference GuidePartitions enables the displa y of par tition b oundar ies. Overset when enabled , displa ys only the solv e cells f or cases with o verset in terfaces. Receptor cells ar e also displa yed if the t ext command define/overset-interfaces/options/render-receptor- cells? is set t o yes . Shrink F actor specifies the amoun t to shr ink fac es and c ells. See Shrinking F aces and C ells in the D ispla y (p.2782 ) for details . Edge Type controls the displa y of edges . (These it ems will not app ear if the Edges option is tur ned off .) All enables the displa y of all mesh edges . Feature enables f eature lines in an outline displa y. See Adding F eatures to an Outline D ispla y (p.2781 ) for details . Outline enables the displa y of the mesh outline . Feature Angle controls the amoun t of detail added t o a f eature outline displa y. See Adding F eatures to an Outline D is- play (p.2781 ) for details . (This it em will b e available only if the Feature edge t ype is enabled .) Surfaces contains a list fr om which y ou c an selec t the sur faces for which the mesh is t o be dr awn. New S urface is a dr op-do wn list butt on tha t contains a list of sur face options: Point opens the Point Sur face Dialog Box (p.3898 ). Line/R ake opens the Line/R ake Sur face Dialog Box (p.3847 ). Plane opens the Plane Sur face Dialog Box (p.3895 ). Quadr ic opens the Quadr ic Sur face Dialog Box (p.3899 ). Iso-S urface opens the Iso-Sur face Dialog Box (p.3842 ). Iso-C lip opens the Iso-C lip D ialog Box (p.3841 ). Structural P oint opens the Structural Point Sur face Dialog Box (p.3928 ). 3241Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Gener al Task P ageOutline selec ts all “outline ” boundar ies in the Surfaces list. If all outline b oundar ies ar e alr eady selec ted, it deselec ts them. Interior selec ts all “interior” surfaces in the Surfaces list. If all in terior sur faces ar e alr eady selec ted, it deselec ts them. Adjac enc y opens the Adjac ency Dialog Box (p.3780 ) from which y ou c an iden tify and displa y fac e zones tha t are adja- cent to selec ted c ell z ones . Color ing Automa tic nodes, edges , and fac es ar e aut oma tically c olor ed b y type or ID , dep ending on which is sp ecified in the Mesh C olors D ialog Box (p.3244 ). Colors ... opens the Mesh C olors D ialog Box (p.3244 ). Manual allows you t o manually sp ecify the c olor of no des, edges , and fac es, if enabled under Options . Nodes specify the c olor f or the no des. Edges specify the c olor f or the edges . Faces specify the c olor f or the fac es. Displa y displa ys the defined mesh plot. Save/D ispla y displa ys the mesh in the ac tive gr aphics windo w and sa ves the mesh displa y definition. This butt on app ears only f or mesh displa y definitions and r eplac es the Displa y butt on. 47.3.3. Set U nits D ialo g Box The Set U nits dialo g box allo ws you t o set the units sy stem f or an y quan tity used in ANSY S Fluen t. All quan tities ma y be set t o a standar d sy stem, such as SI or B ritish, or the units of individual quan tities may be set. See Unit S ystems (p.655) for details ab out the it ems b elow. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3242Task P age R eference GuideControls Quan tities displa ys the list of all quan tities used b y ANSY S Fluen t for input and output. Units lists the units appr opriate for the cur rently selec ted quan tity. Selec ting an it em in the Units list c auses that unit t o be used f or the cur rently selec ted quan tity. Factor displa ys the c onversion fac tor fr om the cur rently selec ted units t o SI. Offset displa ys the c onversion off set fr om the cur rently selec ted units t o SI. Set A ll to contains standar d sets of units tha t are applied t o all quan tities when selec ted. default is similar t o si, but uses degr ees inst ead of r adians f or angles . si selec ts the S ystem In ternational (SI) standar d for all units . british selec ts the English Engineer ing standar d for all units . cgs selec ts the C GS (c entimet er-gr am-sec ond) standar d for all units New... opens the Define U nit D ialog Box (p.3244 ), in which y ou c an sp ecify a cust omiz ed unit f or a par ticular quan tity. List displa ys the cur rent units f or all quan tities in the c onsole . 3243Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Gener al Task P age47.3.4. Define U nit D ialo g Box The Define U nit dialo g box allo ws you t o cust omiz e the units f or a par ticular quan tity. It is op ened from the Set U nits D ialog Box (p.3242 ). For details ab out using this dialo g box, see Defining a N ew Unit (p.657). Controls Quan tity shows the name of the quan tity for which y ou ar e defining a new unit. (You c annot edit this field; the quan tity is selec ted in the Set U nits D ialog Box (p.3242 ).) Unit sets the name f or the new unit. Factor sets the c onversion fac tor fr om the cur rently selec ted units t o SI. Offset sets the c onversion off set fr om the cur rently selec ted units t o SI. 47.3.5. Mesh C olors D ialo g Box The Mesh C olors dialo g box allo ws you t o control the c olors tha t are used t o dr aw meshes . It is op ened from the Mesh D ispla y Dialog Box (p.3239 ). See Modifying the M esh C olors (p.2780 ) for details ab out the items b elow. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3244Task P age R eference GuideControls Options contains options t o selec t the metho d by which t o set the c olors . Color b y Type sets the c olor based on the t ype of z one . Color b y ID sets the c olor b y ID . Types contains a selec table list of z one t ypes.You c an selec t the z one t ype for which y ou w ant to set the c olor . Colors contains a list fr om which y ou c an selec t a c olor f or the selec ted t ype. Sample displa ys a sample of the cur rently selec ted c olor . Reset C olors resets the mesh c olors t o the default selec tions . 47.4. Models Task P age The Models task page allo ws you t o set v arious gener ic mo del settings . 3245Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageControls Models contains a listing of the v arious mo dels a vailable in ANSY S Fluen t. You c an double-click an it em in the Models list t o op en the c orresponding dialo g box, or y ou c an selec t the it em in the list and click the Edit... butt on. Multiphase - selec ting this it em and click ing the Edit... butt on op ens the Multiphase M odel D ialog Box (p.3248 ). Energy - selec ting this it em and click ing the Edit... butt on op ens the Ener gy Dialog Box (p.3252 ). Visc ous - selec ting this it em and click ing the Edit... butt on op ens the Viscous M odel D ialog Box (p.3253 ). Radia tion - selec ting this it em and click ing the Edit... butt on op ens the Radia tion M odel D ialog Box (p.3269 ). Heat Exchanger - selec ting this it em and click ing the Edit... butt on op ens the Heat Exchanger M odel D ialog Box (p.3278 ). Species - selec ting this it em and click ing the Edit... butt on op ens the Species M odel D ialog Box (p.3294 ). The f ollowing mo dels ar e made a vailable , dep ending on y our setup of the Species dialo g box. •Spar k Ignition - selec ting this it em and click ing the Edit... butt on op ens the Spark Ignition D ialog Box (p.3325 ). Note tha t spar k ignition is only a vailable f or tr ansien t calcula tions . •Autoignition - selec ting this it em and click ing the Edit... butt on op ens the Autoignition M odel Dialog Box (p.3327 ). Note tha t aut oignition is only a vailable f or tr ansien t calcula tions . •Iner t - selec ting this it em and click ing the Edit... butt on op ens the Iner t Dialog Box (p.3330 ). Note that the iner t mo del is only a vailable when the non-pr emix ed or par tially pr emix ed mo del is selec ted in the Species M odel dialo g box, or when a PDF file is r ead. •NOx - selec ting this it em and click ing the Edit... butt on op ens the NOx Model D ialog Box (p.3332 ). Note tha t the NO x mo del is not c ompa tible with pr emix ed c ombustion. •SOx - selec ting this it em and click ing the Edit... butt on op ens the SOx Model D ialog Box (p.3339 ). Note tha t the SO x mo del is not c ompa tible with pr emix ed c ombustion. •Soot - selec ting this it em and click ing the Edit... butt on op ens the Soot M odel D ialog Box (p.3343 ). Note tha t none of the so ot mo dels ar e compa tible with pr emix ed c ombustion. •Decoupled D etailed C hemistr y - selec ting this it em and click ing the Edit... butt on op ens the De- coupled D etailed C hemistr y Dialog Box (p.3356 ). •Reac ting C hannel M odel - selec ting this it em and click ing the Edit... butt on op ens the Reacting Channel M odel D ialog Box (p.3356 ). Discr ete Phase - selec ting this it em and click ing the Edit... butt on op ens the Discrete Phase M odel D ialog Box (p.3360 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3246Task P age R eference GuideSolidific ation & M elting - selec ting this it em and click ing the Edit... butt on op ens the Solidific ation and M elting D ialog Box (p.3370 ). Acoustics - selec ting this it em and click ing the Edit... butt on op ens the Acoustics M odel D ialog Box (p.3371 ). Structure - selec ting this it em and click ing the Edit... butt on op ens the Structural M odel D ialog Box (p.3378 ). Euler ian Wall F ilm - selec ting this it em and click ing the Edit... butt on op ens the Euler ian Wall F ilm D ialog Box (p.3379 ). Electric P otential - selec ting this it em and click ing the Edit... butt on op ens the Potential D ialog Box (p.3384 ). Edit... opens the dialo g box corresponding t o the selec ted it em in the Models list. For additional inf ormation, see the f ollowing sec tions: 47.4.1. Multiphase M odel D ialog Box 47.4.2. Ener gy Dialog Box 47.4.3. Viscous M odel D ialog Box 47.4.4. Radia tion M odel D ialog Box 47.4.5. View F actors and C lustering D ialog Box 47.4.6. Participa ting B oundar y Zones D ialog Box 47.4.7. Solar C alcula tor D ialog Box 47.4.8. Heat Exchanger M odel D ialog Box 47.4.9. Dual C ell H eat Exchanger D ialog Box 47.4.10. Set D ual C ell H eat Exchanger D ialog Box 47.4.11. Heat Transf er D ata Table D ialog Box 47.4.12. NTU Table D ialog Box 47.4.13. Copy From D ialog Box 47.4.14. Ungroup ed M acro Heat Exchanger D ialog Box 47.4.15. Velocity Effectiveness C urve Dialog Box 47.4.16. Core Porosity Model D ialog Box 47.4.17. Macro Heat Exchanger G roup D ialog Box 47.4.18. Species M odel D ialog Box 47.4.19. Coal C alcula tor D ialog Box 47.4.20. Integration P aramet ers D ialog Box 47.4.21. Flamelet 3D Sur faces D ialog Box 47.4.22. Flamelet 2D C urves D ialog Box 47.4.23. Unsteady Flamelet P aramet ers D ialog Box 47.4.24. Flamelet F luid Z ones D ialog Box 47.4.25. Selec t Transp orted Sc alars D ialog Box 47.4.26. PDF Table D ialog Box 47.4.27. Spark Ignition D ialog Box 47.4.28. Set Spark Ignition D ialog Box 47.4.29. Autoignition M odel D ialog Box 47.4.30. Iner t Dialog Box 47.4.31. NOx Model D ialog Box 47.4.32. SOx Model D ialog Box 47.4.33. Soot M odel D ialog Box 3247Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P age47.4.34. Sticking C oefficien ts D ialog Box 47.4.35. Mechanism D ialog Box 47.4.36. Reactor N etwork Dialog Box 47.4.37. Decoupled D etailed C hemistr y Dialog Box 47.4.38. Reacting C hannel M odel D ialog Box 47.4.39. Reacting C hannel 2D C urves D ialog Box 47.4.40. Discrete Phase M odel D ialog Box 47.4.41. DEM C ollisions D ialog Box 47.4.42. Create Collision P artner D ialog Box 47.4.43. Copy Collision P artner D ialog Box 47.4.44. Rename C ollision P artner D ialog Box 47.4.45. DEM C ollision S ettings D ialog Box 47.4.46. Solidific ation and M elting D ialog Box 47.4.47. Acoustics M odel D ialog Box 47.4.48. Acoustic S ources D ialog Box 47.4.49. Acoustic R eceivers D ialog Box 47.4.50. Basic S hap es D ialog Box 47.4.51. Interior C ell Z one S elec tion D ialog Box 47.4.52. Structural M odel D ialog Box 47.4.53. Euler ian Wall F ilm D ialog Box 47.4.54. Potential D ialog Box 47.4.1. Multiphase M odel D ialo g Box The Multiphase M odel dialo g box allo ws you t o set par amet ers f or mo deling multiphase flo w. See Enabling the M ultiphase M odel (p.2093 ) – Including C avitation E ffects (p.2199 ) for details . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3248Task P age R eference GuideControls Model allows you t o selec t one of f our multiphase mo dels . Off disables the c alcula tion of multiphase flo w. Volume of F luid enables the VOF mo del descr ibed in Volume of F luid ( VOF) M odel Theor y in the Theor y Guide . See Setting U p the VOF M odel (p.2142 ) for details ab out using the mo del. This is a vailable only with the pressur e-based solv er. 3249Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageMixture enables the mix ture mo del descr ibed in Mixture Model Theor y in the Theor y Guide . See Setting U p the M ixture Model (p.2189 ) for details ab out using the mo del. This is a vailable only with the pr essur e- based solv er. Euler ian enables the E uler ian mo del descr ibed in Euler ian M odel Theor y in the Theor y Guide . See Setting U p the E uler ian M odel (p.2208 ) for details ab out using the mo del. This is a vailable only with the pr essur e- based solv er. Wet S team enables the w et st eam mo del descr ibed in Wet Steam M odel Theor y in the Theor y Guide . See Setting Up the Wet Steam M odel (p.2252 ) for details ab out using the mo del. This is a vailable only with the densit y-based solv er. Numb er of E uler ian P hases allows you t o sp ecify the numb er of phases f or the multiphase c alcula tion. You c an sp ecify up t o 20 phases . Coupled L evel S et + VOF allows you t o apply an in terface tracking metho d tha t couples the le vel set metho d with the VOF f ormu- lation. Volume F raction P aramet ers contains par amet ers r elated t o the VOF and E uler ian mo del. This sec tion of the dialo g box will app ear only when Volume of F luid or Euler ian is the selec ted Model. Formula tion allows you t o selec t the desir ed v olume tr acking f ormula tion. Explicit enables the E uler e xplicit f ormula tion, descr ibed in The Explicit F ormula tion in the Theor y Guide . See Choosing Volume F raction F ormula tion (p.2097 ) for mor e inf ormation. Implicit enables the implicit f ormula tion, descr ibed in The Implicit F ormula tion in the Theor y Guide . See Choosing Volume F raction F ormula tion (p.2097 ) for mor e inf ormation. Volume F raction C utoff specifies a cut off limit f or the v olume fr action v alues .The v alue tha t you pr ovide is used as the lo wer cutoff f or the v olume fr action. All volume fr action v alues in the domain b elow this cut off v alue ar e set t o zero.The upp er cut off is c alcula ted as (1.0 - lo wer cut off). All volume fr action v alues ab ove the upp er cut off v alue ar e set t o 1.0. The default v alue is 1e-6. Imp ortant The Volume F raction C utoff value c an b e sp ecified when using the Explicit formu- lation f or v olume fr action. Cour ant Numb er specifies the maximum C ourant numb er allo wed near the fr ee sur face.This it em will not app ear if the Implicit Scheme is selec ted. See Setting Time-D ependen t Paramet ers f or the Explicit Volume Fraction F ormula tion (p.2179 ) for details . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3250Task P age R eference GuideMixture Paramet ers contains options r elated t o the Mixture mo del. Slip Velocity enables/disables the c alcula tion of slip v elocities f or the sec ondar y phases as descr ibed in Relative (Slip) Velocity and the D rift Velocity in the Theor y Guide . See also Solving a H omo geneous M ultiphase Flow (p.2101 ). Euler ian P aramet ers contains options r elated t o the Euler ian mo del. Dense D iscr ete Phase M odel allows you t o include the D ense D iscrete Phase mo del (see Including the D ense D iscrete Phase Model (p.2236 ) for details). Enabling this mo del aut oma tically enables the DPM mo del. Multi-F luid VOF M odel allows you t o include the multi-fluid VOF mo del (see Including the M ulti-F luid VOF M odel (p.2249 ) for details). The multi-fluid VOF mo del allo ws the mo deling of in terface shar pening schemes and fr ee surface flo w. Boiling M odel allows you t o include the B oiling mo del (see Including the B oiling M odel (p.2241 ) for details). Boiling M odel Options allows you t o selec t the t ype of b oiling mo del t o apply t o your c ase. RPI B oiling M odel is wher e the t otal hea t flux fr om the w all to the liquid is par titioned in to thr ee c omp onen ts, namely the c onvective hea t flux, the quenching hea t flux, and the e vaporative hea t flux. Details about this mo del c an b e found in RPI M odel in the Theor y Guide . Non-equilibr ium B oiling is a mo dific ation t o the RPI mo del in or der t o mo del diff erent boiling r egimes lik e DNB and critical hea t flux. Details ab out this mo del c an b e found in Non-equilibr ium Sub cooled B oiling in the Theor y Guide . Critical H eat Flux is wher e the cr itical hea t flux c ondition is char acterized b y a shar p reduc tion of lo cal hea t transf er coefficien ts and the e xcursion of w all sur face temp eratures. Details ab out this mo del can b e found in Critical H eat Flux in the Theor y Guide . Numb er of D iscr ete Phase allows you t o sp ecify the numb er of discr ete phases when the Dense D iscr ete Phase M odel option is enabled . Body Force Formula tion contains an additional option f or b ody force calcula tions . Implicit B ody Force enables the implicit b ody force treatmen t descr ibed in Including B ody Forces (p.2104 ). VOF S ub-M odels contains additional sub-mo dels tha t can b e applied when using the VOF mo del. 3251Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageOpen C hannel F low enables the mo del t o stud y the eff ects of op en channel flo w. See Open C hannel F low in the Theor y Guide and Modeling Op en C hannel F lows (p.2144 ) for details . Open C hannel Wave BC enables the mo del t o set sp ecific par amet ers f or a par ticular b oundar y for op en channel w ave boundar ies. See Open C hannel Wave Boundar y Conditions in the Theor y Guide and Modeling Op en Channel Wave Boundar y Conditions (p.2154 ) for details . Options contains additional mo deling options . Interface M odeling contains settings f or ho w to mo del in terfaces for the VOF mo del, Mixture multiphase mo del, and Euler ian with M ulti-F luid VOF enabled . See Interface Modeling Type (p.2097 ) for details . Type allows you t o selec t the t ype of in terface mo deling t o be performed .You c an cho ose b etween Sharp,Dispersed , or a h ybrid Sharp/D ispersed when b oth t ypes of in terfaces ma y be pr esen t, or when the in terface is mildly shar p. See Interface Modeling Type (p.2097 ) for mor e details . Interfacial A nti-D iffusion enables an an ti-diffusion tr eatmen t at the in terface when using the Sharp interface mo deling type.This c an b e used t o reduc e the eff ects of numer ical diffusion tha t ma y occur with c oarse meshes , high-asp ect ratio c ells, or lar ge jumps in c ell v olume near the in terface. Interface M odeling Options ... opens the Interface M odeling Options dialo g box from which y ou c an enable Zonal D iscr etiz- ation and/or Phase L ocaliz ed D iscr etiza tion . Expert Options ... opens the Expert Options dialo g box which c ontains settings f or VOF time ad vancemen t when using the Explicit f ormula tion. Here you c an set the Sub-T ime S tep C alcula tion M etho d and enable Solve VOF E very Iteration . See Expert Options (p.2100 ) for details . 47.4.2. Energy Dialo g Box The Energy dialo g box allo ws you t o set par amet ers r elated t o ener gy or hea t transf er in y our mo del. Controls Energy contains inputs r elated t o the mo deling of ener gy. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3252Task P age R eference GuideEnergy Equa tion enables/disables the c alcula tion of ener gy in the mo del. 47.4.3. Visc ous M odel D ialo g Box The Visc ous M odel dialo g box allo ws you t o set par amet ers f or in viscid , laminar , and turbulen t flo w. See Steps in U sing a Turbulenc e M odel (p.1392 ) for details ab out using this dialo g box to set up a tur- bulen t flo w calcula tion. 3253Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageControls Model contains options f or sp ecifying the visc ous mo del. Inviscid specifies in viscid flo w. Laminar specifies laminar flo w. Spalar t-Allmar as specifies turbulen t flo w to be calcula ted using the S palar t-Allmar as mo del. (See Spalar t-Allmar as Model in the Theor y Guide for back ground ab out this mo del. See Setting U p the S palar t-Allmar as Model (p.1395 ) for details ab out using this mo del.) k-epsilon specifies turbulen t flo w to be calcula ted using one of thr ee - mo dels . (See Standar d, RNG, and Realizable k- ε Models in the Theor y Guide for back ground ab out this mo del. See Setting U p the k- ε Model (p.1395 ) for details ab out using this mo del.) k-omega specifies turbulen t flo w to be calcula ted using one of t wo - mo dels . (See Standar d, BSL, and SST k-ω Models in the Theor y Guide for back ground ab out these mo dels . See Setting U p the k- ω Mod- el (p.1401 ) for details ab out using this mo del.) Transition k-k l-omega specifies turbulen t flo w to be calcula ted using the Transition - - mo del. (See k-kl-ω Transition Model in the Theor y Guide for back ground ab out this mo del. See Setting U p the Transition k-k l-ω Model (p.1409 ) for details ab out using this mo del.) Transition SST specifies turbulen t flo w to be calcula ted using the Transition SST mo del. (See Transition SST M odel in the Theor y Guide for back ground ab out this mo del. See Setting U p the Transition SST M odel (p.1409 ) for details ab out using this mo del.) Reynolds S tress specifies turbulen t flo w to be calcula ted using the RSM. (See Reynolds S tress M odel (RSM) in the Theor y Guide for back ground ab out this mo del. See Setting U p the R eynolds S tress M odel (p.1413 ) for details ab out using this mo del.) Scale-A daptiv e Simula tion (SAS) specifies turbulen t flo w to be calcula ted using the SAS mo del in c ombina tion with the SST - model. (See Scale-A daptiv e Simula tion (SAS) M odel in the Theor y Guide for back ground ab out this model. See Setting U p Sc ale-A daptiv e Simula tion (SAS) M odeling (p.1418 ) for details ab out using this model.) Detached E ddy Simula tion specifies turbulen t flo w to be calcula ted using the DES mo del. (See Detached E ddy Simula tion (DES) in the Theor y Guide for back ground ab out this mo del. See Setting U p the D etached E ddy Simula tion Model (p.1420 ) for details ab out using this mo del.) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3254Task P age R eference GuideLarge E ddy Simula tion (3D only) sp ecifies turbulen t flo w to be calcula ted using the LES mo del. (See Large E ddy Simula tion (LES) M odel in the Theor y Guide for back ground ab out this mo del. See Setting U p the Lar ge E ddy Simula tion M odel (p.1431 ) for details ab out using this mo del.) Spalar t-Allmar as P roduc tion contains options f or the S palar t-Allmar as mo del. This p ortion of the dialo g box will app ear only if Spalar t- Allmar as is selec ted as the Model. Vorticit y-Based selec ts the v orticit y-based c alcula tion of the def ormation t ensor (see Equa tion 4.22 in the Theor y Guide ). Strain/V orticit y-Based selec ts the str ain/v orticit y-based c alcula tion of the def ormation t ensor (see Equa tion 4.24 in the Theor y Guide ). k-epsilon M odel contains options f or sp ecifying which of the - mo dels is t o be used .This p ortion of the dialo g box will app ear only if k-epsilon is selec ted as the Model. Standar d selec ts the standar d - mo del, descr ibed in Standar d k-ε Model in the Theor y Guide and Setting U p the k- ε Model (p.1395 ). RNG selec ts the RNG - mo del, descr ibed in RNG k- ε Model. in the Theor y Guide and Setting U p the k- ε Model (p.1395 ). Realizable selec ts the r ealizable - mo del, descr ibed in Realizable k- ε Model in the Theor y Guide and Setting Up the k- ε Model (p.1395 ). RNG Options specifies par amet ers tha t aff ect the solution of pr oblems solv ed with the RNG - mo del. This p ortion of the dialo g box will app ear only if RNG is selec ted as the k-epsilon M odel. Differential Visc osit y M odel specifies whether or not the lo w-R eynolds-numb er RNG mo dific ations t o turbulen t visc osity should be included . By default , this option is tur ned off . It is lik ely t o ha ve an eff ect only when the near-w all regions in the domain ar e well resolv ed in t erms of mesh densit y. See Differential Viscosity Modific a- tion (p.1440 ) for details . Swirl Domina ted F low specifies whether or not the RNG mo dific ation t o turbulen t visc osity for swir ling flo ws should b e in- cluded .This option is a vailable only in 3D and 2D axisymmetr ic swir l solv ers, and it c an yield impr oved predic tions when solving flo ws with signific ant swir l. See Swirl Modific ation (p.1440 ) for details . k-omega M odel contains options f or sp ecifying which of the - mo dels is t o be used .This p ortion of the dialo g box will app ear only if k-omega is selec ted as the Model. 3255Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageStandar d selec ts the standar d - mo del, descr ibed in Standar d k-ω Model in the Theor y Guide and Setting Up the k- ω Model (p.1401 ). GEK O selec ts the gener alized - mo del, descr ibed in Gener alized k-ω (GEK O) M odel in the Theor y Guide and Setting up the G ener alized k-ω (GEK O) M odel (p.1406 ). BSL selec ts the baseline (BSL) - mo del, descr ibed in Baseline (BSL) k- ω Model in the Theor y Guide and Setting U p the k- ω Model (p.1401 ). SST selec ts the shear-str ess tr ansp ort (SST ) - mo del, descr ibed in Shear-S tress Transp ort (SST ) k-ω Model in the Theor y Guide and Setting U p the k- ω Model (p.1401 ). k-omega Options specifies par amet ers tha t aff ect the solution of pr oblems solv ed with the - mo dels .This p ortion of the dialo g box will app ear only if k-omega is selec ted as the Model. Low-Re C orrections specifies whether c orrections tha t impr ove the accur acy in pr edic ting lo w Reynolds numb er flo ws should b e included .This option is a vailable only f or the - mo dels and the str ess-omega RSM model. See Low-R e Corrections (p.1440 ) for details . Shear F low C orrections specifies whether c orrections tha t impr ove the accur acy in pr edic ting fr ee shear flo ws should b e in- cluded .This option is a vailable only f or the standar d - mo del and the str ess-omega RSM mo del. See Shear F low Corrections (p.1440 ) for details . Turbulenc e Damping includes the eff ects of turbulenc e damping in multiphase simula tions , which is r equir ed f or b etter resolution of v elocity gr adien ts in the vicinit y of fluid-fluid in terface.When this option is enabled , you will need t o sp ecify Damping F actor (default = 10). This option is a vailable f or the VOF and M ixture models and f or the E uler ian multiphase mo del with the Multi-F luid VOF mo del selec ted. See Turbu- lenc e Damping (p.1441 ) for details . Transition SST Options allows you t o include the Roughness C orrelation of r ough w alls as descr ibed in Transition SST and R ough Walls in the Theor y Guide . Roughness C orrelation when enabled allo ws you t o sp ecify the Geometr ic Roughness H eigh t as a c onstan t value . Reynolds-S tress M odel specifies the v arious R eynolds str ess mo dels (RSM). Linear P ressur e-Strain enables the linear pr essur e-str ain mo del. See Linear P ressur e-Strain M odel in the Theor y Guide for details . Quadr atic P ressur e-Strain enables the quadr atic pr essur e-str ain mo del f or sup erior p erformanc e in a r ange of basic shear flo ws, including plane str ain, rotating plane shear , and axisymmetr ic expansion/c ontraction. See Quadr atic Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3256Task P age R eference GuidePressur e-Strain M odel in the Theor y Guide for details . Note tha t this option c annot b e used with the Wall Reflec tion E ffects option or the Enhanc ed Wall Treatmen t. Stress-Omega enables a str ess-tr ansp ort mo del tha t is based on the omega equa tions and LRR mo del [145] (p.4013 ). This mo del is ideal f or mo deling flo ws over cur ved sur faces and swir ling flo ws. See Stress-Omega Model in the Theor y Guide for details . Stress-BSL enables a linear mo del f or the pr essur e-str ain t erm lik e the Stress-Omega mo del, but solv es the sc ale equa tion fr om the baseline (BSL) - mo del, and thus r emo ves the fr ee-str eam sensitivit y obser ved with the Stress-Omega mo del. Like the Stress-Omega mo del, it is r ecommended f or mo deling flo ws over cur ved sur faces and swir ling flo ws. See Stress-BSL M odel in the Theor y Guide for details . Reynolds-S tress Options specifies par amet ers tha t aff ect the solution of pr oblems solv ed with the R eynolds str ess mo del. This portion of the dialo g box will app ear only if Reynolds S tress is selec ted as the Model. Wall BC fr om k E qua tion enables the e xplicit setting of b oundar y conditions f or the R eynolds str esses near the w alls, using the values c omput ed with Equa tion 4.233 in the Theor y Guide . See Solving the k E qua tion t o Obtain Wall Boundar y Conditions (p.1442 ) for details .This option is on b y default. Wall Reflec tion E ffects enables the c alcula tion of the c omp onen t of the pr essur e str ain t erm responsible f or the r edistr ibution of nor mal str esses near the w all. See Including the Wall R eflec tion Term (p.1441 ) for details . Note tha t this option is not a vailable if y ou ha ve enabled the Quadr atic P ressur e-Strain M odel. RANS M odel contains options f or the sub grid-sc ale mo del used b y the Detached E ddy Simula tion M odel.This p ortion of the dialo g box will app ear only if Detached E ddy Simula tion M odel is selec ted as the Model. Spalar t-Allmar as enables the S palar t-Allmar as R ANS mo del. See Detached E ddy Simula tion (DES) in the Theor y Guide for details . Realizable k-epsilon enables the R ealizable - RANS mo del. See Detached E ddy Simula tion (DES) in the Theor y Guide for details . SST k-omega enables the SST - RANS M odel. See Detached E ddy Simula tion (DES) in the Theor y Guide for details . DES Options contain the option t o include a dela yed D etached E ddy Simula tion. Delayed DES is useful f or R ANS meshes with high asp ect ratios in the b oundar y layer.This option pr eser ves the RANS mo del thr oughout the b oundar y layer. (See Delayed D etached E ddy Simula tion (DDES) (p.1440 ) for details .) Subgrid-Sc ale M odel contains options f or the sub grid-sc ale mo del used b y the LES mo del. This p ortion of the dialo g box will app ear only if Large E ddy Simula tion is selec ted as the Model. 3257Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageSmagor insk y-Lilly selec ts the S magor insk y-Lilly sub grid-sc ale mo del descr ibed in Sub grid-Sc ale M odels in the Theor y Guide . WALE selec ts the Wall-A dapting lo cal Eddy-Viscosity mo del descr ibed in Wall-A dapting L ocal Eddy-Viscosity (WALE) M odel in the Theor y Guide . WMLES selec ts the algebr aic Wall-M odeled LES mo del descr ibed in Algebr aic Wall-M odeled LES M odel ( WMLES) in the Theor y Guide . WMLES S-Omega selec ts the algebr aic Wall-M odeled LES - mo del descr ibed in Algebr aic WMLES S-Omega M odel Formula tion in the Theor y Guide . Kinetic-E nergy Transp ort selec ts the d ynamic k inetic ener gy sub grid-sc ale mo del descr ibed in Dynamic K inetic Ener gy Sub grid- Scale M odel in the Theor y Guide . LES M odel Options contains options f or the Lar ge E ddy Simula tion mo del. This p ortion of the dialo g box will app ear only if Large E ddy Simula tion is selec ted as the Model. Dynamic S tress enables the d ynamic str ess mo del. It is a vailable f or selec tion when the Smagor insk y-Lilly is selec ted, and is enabled (and c annot b e disabled) when the Kinetic-E nergy Transp ort is selec ted. Dynamic E nergy Flux enables the d ynamic ener gy flux mo del. It is a vailable when the LES mo del option Dynamic S tress is enabled . Dynamic Sc alar F lux enables the d ynamic c omputa tion of turbulen t Sc ( in Equa tion 8.5 in the Theor y Guide ). See Definition of the M ixture Fraction in the Theor y Guide for details . It is a vailable when the LES mo del option Dynamic S tress is enabled . Dynamic Fv ar enables the d ynamic mix ture fraction v arianc e mo del. It is a vailable when Non-P remix ed C ombustion or Partially P remix ed C ombustion is selec ted in the Species M odel D ialog Box (p.3294 ). See The N on- Premix ed M odel f or LES in the Theor y Guide for details . Near-W all Treatmen t specifies the near-w all tr eatmen t to be used f or mo deling turbulenc e. See Near-W all Treatmen ts for Wall- Bounded Turbulen t Flows in the Theor y Guide for details ab out the a vailable metho ds.This p ortion of the dialo g box will app ear if k-epsilon or Reynolds S tress is selec ted as the Model. Standar d Wall F unc tions enables the use of standar d wall func tions (descr ibed in Standar d Wall F unctions in the Theor y Guide). Scalable Wall F unc tions enables the use of sc alable w all func tions (descr ibed in Scalable Wall F unctions in the Theor y Guide). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3258Task P age R eference GuideNon-E quilibr ium Wall F unc tions enables the use of non-equilibr ium w all func tions (descr ibed in Non-E quilibr ium Wall F unctions in the Theor y Guide ). Enhanc ed Wall Treatmen t enables the use of the enhanc ed w all tr eatmen t (descr ibed in Enhanc ed Wall Treatmen t ε-Equa tion (EWT-ε) in the Theor y Guide). Note tha t this option will not app ear if y ou ha ve enabled the Quadr atic Pressur e-Strain M odel under Reynolds-S tress Options . Menter-L echner enables the use of the M enter-L echner near-w all tr eatmen t (descr ibed in Menter-L echner ε-Equa tion (ML-ε) in the Theor y Guide). Note tha t this option is only a vailable when k-epsilon is selec ted f or the Model. User-D efined Wall F unc tions enables y ou t o ho ok a user-defined func tion, used t o define the Law of the Wall. See User-D efined Wall F unctions in the Theor y Guide for mor e inf ormation. Enhanc ed Wall Treatmen t Options allows you t o include pr essur e gr adien t or ther mal eff ects in the c alcula tion. See Near-W all Treatmen ts for Wall-B ounded Turbulen t Flows in the Theor y Guide . Pressur e Gradien t Effects enables the eff ect of pr essur e gr adien t. Thermal E ffects enables ther mal eff ects in the c alcula tion. This option app ears only if the ener gy equa tion is enabled . Options contains gener al options f or visc ous mo deling . Visc ous H eating (if enabled) includes the visc ous dissipa tion t erms in the ener gy equa tion. This option is r ecommended when y ou ar e solving a c ompr essible flo w. Note tha t this option is alw ays tur ned on when one of the densit y-based solv ers is used; you will not b e able t o tur n it off . Low-P ressur e Boundar y Slip includes slip b oundar y conditions f or v elocity and t emp erature for mo deling fluid flo w at very low pressur es as in semic onduc tor fabr ication de vices. See Slip B oundar y Formula tion f or Low-Pressur e Gas S ystems in the Theor y Guide .This option is a vailable only f or laminar flo ws. Full Buo yanc y Effects enables the inclusion of buo yancy eff ects on . See Including Turbulenc e Gener ation D ue t o Buoy- ancy (p.1437 ) for details .This option will app ear if k-epsilon or Reynolds S tress is selec ted as the Model and a nonz ero gr avitational acc eleration has b een sp ecified in the Operating C onditions D ialog Box (p.3470 ). Curvature Correction when enabled , mo difies the turbulenc e pr oduc tion t erm to sensitiz e the standar d edd y-visc osity models t o the eff ects of str eamline cur vature and sy stem r otation. This is a vailable f or the Spalar t- Allmar as,k-epsilon ,k-omega ,Transition SST ,Scale-A daptiv e Simula tion , and Detached E ddy Simula tion with the SST k-omega mo del. 3259Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageCurvature Correction Options CCUR V specifies a c oefficien t used in the cur vature correction t erm to influenc e the str ength of the curvature correction if needed f or a sp ecific flo w. Can b e a c onstan t or sp ecified via UDF . Compr essibilit y Effects when enabled , can impr ove the pr edic tion of fr ee shear la yers a t high M ach numb ers.This is a vailable when the c ompr essible f orm of the ideal gas la w or the r eal-gas mo del is ac tivated f or k-epsilon ,k- omega ,Transition k-k l-omega ,Reynolds S tress,Scale-A daptiv e Simula tion , and Detached E ddy Simula tion with the Realizable k-epsilon mo del. For details , see Model Enhanc emen ts (p.1383 ). Mixture Drift Force includes the eff ect of turbulen t drift velocity when using the Mixture mo del. See Modeling Turbu- lenc e (p.2229 ). Note tha t this option is only a vailable when using the Mixture mo del with Slip Velocity enabled in the Multiphase M odel dialo g box. See Including M ixture Drift Force (p.2198 ). Produc tion K ato-Launder when enabled , the K ato-Launder mo dific ation f or the pr oduc tion t erm limits the pr oduc tion t erm in the turbulenc e equa tion. For details see ,Produc tion Limit ers f or Two-Equa tion M odels in the Fluent Theor y Guide . Produc tion Limit er when enabled , limits the pr oduc tion t erm in the turbulenc e equa tion. For details , see Produc tion Limit ers f or Two-Equa tion M odels in the Fluent Theor y Guide . Intermitt enc y Transition M odel enables the In termitt ency Transition mo del t o acc oun t for tr ansitional eff ects.This option is only available f or the BSL - , SST - , Scale-A daptiv e Simula tion with BSL / SST , and D etached E ddy Simula tion with BSL / SST mo dels . For details , see Intermitt ency Transition M odel in the Theor y Guide . Intermitt enc y Transition Options contains an option f or the In termitt ency Transition mo del. This gr oup b ox is only a vailable when the In- termitt enc y Transition M odel option is enabled . Include C rossflo w Transition includes the eff ects of cr ossflo w instabilit y. For details , see Transp ort Equa tions f or the In termitt ency Transition M odel in the Theor y Guide . Turbulenc e M ultiphase M odel contains options f or multiphase turbulenc e mo dels .This p ortion of the dialo g box will app ear if Euler ian is selec ted as the Model in the Multiphase M odel D ialog Box (p.3248 ). Mixture specifies the (default) mix ture turbulenc e mo del. Dispersed specifies the disp ersed turbulenc e mo del. Per P hase specifies the c alcula tion of a set of turbulenc e equa tions f or each phase . See Turbulenc e M odels in the Theor y Guide for details ab out the a vailable multiphase turbulenc e models . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3260Task P age R eference GuideGEK O Options contains options f or the GEK O mo del. Wall D istanc e Free Selec ts the w all distanc e free v ersion of the GEK O mo del. CSEP Specifies - par amet er to optimiz e flo w separ ation fr om smo oth sur faces. CNW Specifies - par amet er to optimiz e flo w in non-equilibr ium near w all regions (such as hea t transf er or ). CMIX Specifies - par amet er to optimiz e str ength of mixing in fr ee shear flo ws. CJET Specifies - par amet er to optimiz e free shear la yer mixing (optimiz e free jets indep enden t of mixing la yer). Blending F unc tion Specifies the blending func tion, , which deac tivates these par amet ers inside b oundar y layers. See Gener alized k-ω (GEK O) M odel in the Fluent Theor y Guide for details ab out the GEK O mo del options . Model C onstan ts contains c onstan ts used in the equa tions f or turbulenc e. See Spalar t-Allmar as M odel,Standar d k-ε Model, RNG k- ε Model,k-kl-ω Transition M odel,Transition SST M odel,Realizable k- ε Model,Reynolds S tress Model (RSM) ,Standar d k-ω Model,Shear-S tress Transp ort (SST ) k-ω Model, and Large E ddy Simula tion (LES) M odel in the Theor y Guide for details ab out these c onstan ts. Cb1 (only f or the S palar t-Allmar as mo del) is the c onstan t in Equa tion 4.19 in the Theor y Guide . Cb2 (only f or the S palar t-Allmar as mo del) is the c onstan t in Equa tion 4.15 in the Theor y Guide . Cv1 (only f or the S palar t-Allmar as mo del) is the c onstan t in Equa tion 4.17 in the Theor y Guide . Cw2 (only f or the S palar t-Allmar as mo del) is the c onstan t in Equa tion 4.28 in the Theor y Guide . Cw3 (only f or the S palar t-Allmar as mo del) is the c onstan t in Equa tion 4.27 in the Theor y Guide . Cpr od (only f or the S palar t-Allmar as mo del when the Strain/V orticit y-Based P roduc tion option is used) is the c onstan t in Equa tion 4.24 in the Theor y Guide . 3261Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageCmu (only f or the standar d or RNG - mo del, the RSM, or the - - Transition mo del) is the c onstan t that is used t o comput e . C1-E psilon (only f or the standar d or RNG - mo del or the RSM) is the c onstan t used in the tr ansp ort equa tion for . C2-E psilon (only f or the standar d, RNG, or r ealizable - mo del or the RSM) is the c onstan t used in the transp ort equa tion f or . C3-E psilon (only f or the disp ersed or p er-phase - multiphase mo dels) is the c onstan t in Equa tion 18.373 in the Theor y Guide . C-lamb da (only f or the - - Transition mo del) is the c onstan t in the definition of the eff ective length, CR (only f or the - - Transition mo del) is the c onstan t used in the definition of , wher e represen ts the a veraged eff ect of the br eakdo wn of str eamwise fluc tuations in to turbulenc e dur ing b ypass transition ANA T (only f or the - - Transition mo del) is the c onstan t ATS (only f or the - - Transition mo del) is the c onstan t CNA T, crit (only f or the - - Transition mo del) is the c onstan t CTS, crit (only f or the - - Transition mo del) is the c onstan t CRNA T (only f or the - - Transition mo del) is the c onstan t Anu (only f or the - - Transition mo del) is the c onstan t CINT (only f or the - - Transition mo del) is the c onstan t Cw1 (only f or the - - Transition mo del) is the c onstan t Cw3 (only f or the - - Transition mo del) is the c onstan t Calpha-t eta (only f or the - - Transition mo del) is the c onstan t Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3262Task P age R eference GuideCtaul (only f or the - - Transition mo del) is the c onstan t SDR P randtl N umb er (only f or the standar d - mo del and the - - Transition mo del) is the eff ective “Prandtl ” numb er for the tr ansp ort of the sp ecific dissipa tion r ate, . Ca1 (only f or the Transition SST mo del) Ca2 (only f or the Transition SST mo del) Ce1 (only f or the Transition SST mo del) Ce2 (only f or the Transition SST mo del) C_theta t (only f or the Transition SST mo del) C_s1 (only f or the Transition SST mo del) Intermit. Prandtl #) (only f or the Transition SST mo del) Re_theta. Prandtl #) (only f or the Transition SST mo del) C Shielded DES (only f or the SDES or SBES mo del) is a c onstan t tha t ser ves the same pur pose as in the DDES tur- bulenc e mo del (see Equa tion 4.257 in the Theor y Guide ). Csdes (only f or the SDES or SBES mo del) is , as descr ibed in Shielded D etached E ddy Simula tion (SDES) in the Theor y Guide . Cwale (only f or the WALE sub grid-sc ale mo del of the LES or SBES mo del) is , as descr ibed in Wall-A dapting Local Eddy-Viscosity (WALE) M odel in the Theor y Guide . CREAL (GEK O) (only f or the GEK O mo del) is , as descr ibed in Gener alized k-ω (GEK O) M odel in the Fluent Theor y Guide . CNW_SUB (GEK O) (only f or the GEK O mo del) is , as descr ibed in Gener alized k-ω (GEK O) M odel in the Fluent Theor y Guide . CJET_A UX (GEK O) (only f or the GEK O mo del) is , as descr ibed in Gener alized k-ω (GEK O) M odel in the Fluent Theor y Guide . 3263Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageCBF_TUR (GEK O) (only f or the GEK O mo del) is , as descr ibed in Gener alized k-ω (GEK O) M odel in the Fluent Theor y Guide . CBF_L AM (GEK O) (only f or the GEK O mo del) is , as descr ibed in Gener alized k-ω (GEK O) M odel in the Fluent Theor y Guide . Swirl Factor sets the v alue of in Equa tion 4.46 in the Theor y Guide .This it em app ears f or the RNG - mo del when the Swirl Domina ted F low option is tur ned on. Alpha*_inf (only f or the standar d, BSL, or SST - mo del, and the Transition SST mo del) is the c onstan t in Equa tion 4.74 in the Theor y Guide . Alpha_inf (only f or the standar d, BSL, or SST - mo del, and the Transition SST mo del) is the c onstan t in Equa tion 4.82 in the Theor y Guide . Alpha_0 (only f or the standar d, BSL, or SST - mo del with the Low-Re C orrections option enabled) is the constan t in Equa tion 4.82 in the Theor y Guide . Beta*_inf (only f or the standar d, BSL, or SST - mo del, and the Transition SST mo del) is the c onstan t in Equa tion 4.87 in the Theor y Guide . Beta_i (only f or the standar d - mo del) is the c onstan t in Equa tion 4.95 in the Theor y Guide . R_b eta (only f or the standar d, BSL, or SST - mo del) is the c onstan t in Equa tion 4.87 in the Theor y Guide . R_k (only f or the standar d, BSL, or SST - mo del with the Low-Re C orrections option enabled) is the constan t in Equa tion 4.74 in the Theor y Guide . R_w (only f or the standar d, BSL, or SST - mo del with the Low-Re C orrections option enabled) is the constan t in Equa tion 4.82 in the Theor y Guide . Zeta* (only f or the standar d, BSL, or SST - mo del when the Compr essibilit y Effects option is enabled) is the c onstan t in Equa tion 4.86 in the Theor y Guide . Mt0 (only f or the standar d, BSL, or SST - mo del when the Compr essibilit y Effects option is enabled) is the c onstan t in Equa tion 4.96 in the Theor y Guide . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3264Task P age R eference Guidea1 (only f or the SST - mo del, and the Transition SST mo del) is the c onstan t in Equa tion 4.117 in the Theor y Guide . Beta_i (Inner) (only f or the BSL or SST - mo del, and the Transition SST mo del) is the c onstan t in Model C on- stan ts in the Theor y Guide . Beta_i (Out er) (only f or the BSL or SST - mo del, and the Transition SST mo del) is the c onstan t in Model C on- stan ts in the Theor y Guide . Cs is a c onstan t tha t dep ends on the turbulenc e mo del. For LES, it is the S magor insk y constan t in Equa tion 4.280 in the Theor y Guide . For SAS, it is the high w ave numb er damping c oefficien t in Equa tion 4.243 in the Theor y Guide . C1-PS (only f or RSM) is the c onstan t in Equa tion 4.204 in the Theor y Guide . C2-PS (only f or RSM) is the c onstan t in Equa tion 4.205 in the Theor y Guide . C1’-PS (only f or RSM) is the c onstan t in Equa tion 4.206 in the Theor y Guide . C2’-PS (only f or RSM) is the c onstan t in Equa tion 4.206 in the Theor y Guide . C1-SSG-PS (only f or RSM with the Quadr atic P ressur e-Strain M odel) is the c onstan t in Equa tion 4.215 in the Theor y Guide . C1’-SSG-PS (only f or RSM with the Quadr atic P ressur e-Strain M odel) is the c onstan t in Equa tion 4.215 in the Theor y Guide . C2-SSG-PS (only f or RSM with the Quadr atic P ressur e-Strain M odel) is the c onstan t in Equa tion 4.215 in the Theor y Guide . C3-SSG-PS (only f or RSM with the Quadr atic P ressur e-Strain M odel) is the c onstan t in Equa tion 4.215 in the Theor y Guide . C3’-SSG-PS (only f or RSM with the Quadr atic P ressur e-Strain M odel) is the c onstan t in Equa tion 4.215 in the Theor y Guide . C4-SSG-PS (only f or RSM with the Quadr atic P ressur e-Strain M odel) is the c onstan t in Equa tion 4.215 in the Theor y Guide . 3265Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageC5-SSG-PS (only f or RSM with the Quadr atic P ressur e-Strain M odel) is the c onstan t in Equa tion 4.215 in the Theor y Guide . Prandtl N umb er (only f or the S palar t-Allmar as mo del) is the c onstan t in Equa tion 4.15 in the Theor y Guide . TKE P randtl N umb er (only f or the standar d or r ealizable - mo del, the standar d - mo del, the - - Transition mo del, or the RSM) is the eff ective “Prandtl ” numb er for tr ansp ort of turbulenc e kinetic ener gy .This eff ective Prandtl numb er defines the r atio of the momen tum diffusivit y to the diffusivit y of turbulenc e kinetic ener gy via turbulen t transp ort. TKE (Inner) P randtl # (only f or the BSL or SST - mo del, and the Transition SST mo del) is the eff ective “Prandtl ” numb er for the tr ansp ort of turbulenc e kinetic ener gy, , inside the near-w all region. See Modeling the Turbulen t Viscosity in the Theor y Guide for details . TKE (Out er) P randtl # (only f or the BSL or SST - mo del, and the Transition SST mo del) is the eff ective “Prandtl ” numb er for the tr ansp ort of turbulenc e kinetic ener gy, , outside the near-w all region. See Modeling the Turbulen t Viscosity in the Theor y Guide for details . TDR P randtl N umb er is the eff ective “Prandtl ” numb er for tr ansp ort of the turbulen t dissipa tion r ate, , for the standar d or realizable - mo del or the RSM. This eff ective Prandtl numb er defines the r atio of the momen tum diffusivit y to the diffusivit y of turbulenc e dissipa tion via turbulen t transp ort. SDR (Inner) P randtl # (only f or the BSL or SST - mo del, and the Transition SST mo del) is the eff ective “Prandtl ” numb er for the tr ansp ort of the sp ecific dissipa tion r ate, , inside the near-w all region. See Modeling the Turbulen t Viscosity in the Theor y Guide for details . SDR (Out er) P randtl # (only f or the BSL or SST - mo del, and the Transition SST mo del) is the eff ective “Prandtl ” numb er for the tr ansp ort of the sp ecific dissipa tion r ate, , outside the near-w all region. See Modeling the Turbulen t Viscosity in the Theor y Guide for details . Dispersion P randtl N umb er (only f or the - multiphase mo dels) is the eff ective “Prandtl ” numb er for the disp ersed phase , . See Turbulenc e Models in the Theor y Guide for details . Energy Prandtl N umb er (for an y turbulenc e mo del e xcept the RNG - mo del) is the turbulen t Prandtl numb er for ener gy, , in Equa tion 4.223 in the Theor y Guide . (This it em will not app ear f or the LES mo del if the Dynamic Energy Flux option has b een enabled , or f or pr emix ed or par tially pr emix ed c ombustion mo dels .) For non-pr emix ed and par tially pr emix ed c ombustion, the ener gy Prandtl N umb er is set equal t o the PDF Schmidt N umb er. Wall P randtl N umb er (for all turbulenc e mo dels) is the turbulen t Prandtl numb er at the w all, in Equa tion 4.319 in the Theor y Guide . (This it em will not app ear f or adiaba tic pr emix ed c ombustion or par tially pr emix ed combustion mo dels .) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3266Task P age R eference GuideTurbulen t Schmidt N umb er (for turbulen t species tr ansp ort calcula tions using an y turbulenc e mo del e xcept the RNG - mo del) is the turbulen t Schmidt numb er, , in Equa tion 7.3 in the Theor y Guide . (This it em will not app ear for the LES mo del if the Dynamic Sc alar F lux option has b een enabled .) PDF Schmidt N umb er (for non-pr emix ed or par tially pr emix ed c ombustion c alcula tions using an y turbulenc e mo del) is the model c onstan t in Equa tion 8.5 in the Theor y Guide . Produc tion Limit er C lip F actor This c oefficien t is used b y the Produc tion Limit er. For details , see Equa tion 4.382 in the Fluent Theor y Guide . User-D efined Transition C orrelations (only f or the Transition SST mo del) allo ws you t o selec t the user-defined c orrelations f or F_length , Re_thetac ,Re_theta t. User-D efined F unc tions allows you t o selec t the user-defined func tions f or v arious c onstan ts. Turbulen t Visc osit y app ears f or S palar t Allmar as, - , - , DES, SDES with BSL / SST mo dels , and SBES with BSL / SST . You c an selec t the user-defined func tions f or turbulen t visc osity in the dr op-do wn list. Prandtl N umb ers,Prandtl and Schmidt N umb ers contains a list of r elevant Prandtl and Schmidt numb ers f or which y ou c an selec t user-defined func tions . TKE P randtl N umb er allows you t o selec t a user-defined func tion t o define the TKE P randtl numb er for the standar d and r ealizable - mo dels and the standar d - mo del. TDR P randtl N umb er allows you t o selec t a user-defined func tion t o define the TDR P randtl numb er for the standar d and r ealizable - mo dels . Energy Prandtl N umb er allows you t o selec t a user-defined func tion t o define the turbulen t Prandtl numb er for ener gy, when ener gy is enabled f or all turbulenc e mo dels e xcept the RNG - mo del. (This it em will not app ear f or the LES mo del if the Dynamic E nergy Flux option has b een enabled .) Wall P randtl N umb er allows you t o selec t a user-defined func tion t o define the turbulen t Prandtl numb er at the w all for all turbulenc e mo dels when ener gy is enabled . Turbulen t Schmidt N umb er allows you t o selec t a user-defined func tion t o define the turbulen t Schmidt numb er when sp ecies transp ort is enabled f or all turbulenc e mo dels e xcept the RNG - mo del. (This it em will not app ear for the LES mo del if the Dynamic Sc alar F lux option has b een enabled .) SDR P randtl N umb er allows you t o selec t a user-defined func tion t o define the SDR P randtl numb er for the standar d - mo del. 3267Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageSubgrid-Sc ale Turbulen t Visc osit y allows you t o selec t a user-defined func tion f or the sub grid-sc ale turbulen t visc osity for the LES model. Scale-Resolving S imula tion Options allows you t o combine t wo turbulenc e mo dels , which ar e applied on the appr opriate regions of the flo w domain. For additional inf ormation, see Scale-R esolving S imula tion (SRS) M odels (p.1385 ). Scale-A daptiv e Simula tion (SAS) allows you t o apply SAS in c ombina tion with the f ollowing -based UR ANS mo dels: the S tandar d or BSL - mo del, the Transition SST mo del, and the -based R eynolds str ess mo dels . For additional information, see Setting U p Sc ale-A daptiv e Simula tion (SAS) M odeling (p.1418 ). Detached E ddy Simula tion (DES) allows you t o apply DES in c ombina tion with the BSL - mo del and Transition SST mo del. For addi- tional inf ormation, see Detached E ddy Simula tion (DES) (p.1386 ). Stress Blending (SBES) / S hielded DES allows you t o apply SBES or SDES in c ombina tion with the BSL - mo del, SST - mo del, and Transition SST mo del. See Stress-B lended E ddy Simula tion (SBES) and Shielded D etached E ddy Simu- lation (SDES) in the Theor y Guide for details . Shielding F unc tions allows you t o selec t the shielding func tions ( SST F1 F unc tion ,SST F2 F unc tion ,DDES , and IDDES ) for the D etached E ddy Simula tion mo del with the BSL - mo del, SST - mo del, and Transition SST mo del. (see Shielding F unctions f or the BSL / SST / Transition SST D etached E ddy Simula tion M odel (p.1448 ) for details). SBES / SDES Options allows you t o define the f ollowing settings as par t of the SBES or SDES mo del: Hybr id M odel specifies tha t the h ybrid R ANS-LES mo del used is either SDES (Shielded DES mo del), SBES (Stress- Blended E ddy Simula tion mo del), or SBES with U ser-D efined F unc tion . See Including the SDES or SBES M odel with BSL, SST , and Transition SST M odels (p.1444 ) for details . Subgrid-Sc ale M odel contains options f or the sub grid-sc ale mo del used in the LES r egion of y our S tress-B lended E ddy Simula tion. This p ortion of the dialo g box will app ear only if SBES or SBES with U ser-D efined Func tion is selec ted as the Hybr id M odel. Smagor insk y-Lilly selec ts the S magor insk y-Lilly sub grid-sc ale mo del descr ibed in Sub grid-Sc ale M odels in the Theor y Guide . Dynamic S magor insk y selec ts the S magor insk y-Lilly sub grid-sc ale mo del (descr ibed in Sub grid-Sc ale M odels in the Theor y Guide ) with the d ynamic str ess mo del enabled . WALE selec ts the Wall-A dapting lo cal Eddy-Viscosity mo del descr ibed in Wall-A dapting L ocal Eddy-Vis- cosity (WALE) M odel in the Theor y Guide . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3268Task P age R eference GuideWMLES S-Omega selec ts the algebr aic Wall-M odeled LES - mo del descr ibed in Algebr aic WMLES S-Omega Model F ormula tion in the Theor y Guide . Update In terval k-omega Sets the numb er of time st eps b etween up dates of the - par t of the SBES mo del. 47.4.4. Radia tion M odel D ialo g Box The Radia tion M odel dialo g box allo ws you t o selec t a mo del f or radia tion hea t transf er and set the asso ciated par amet ers. See Using the R adia tion M odels (p.1489 ) – Defining N on-G ray Radia tion f or the DO M odel (p.1510 ) for details ab out the it ems b elow. Controls Model indic ates which mo del, if an y, is used t o calcula te radia tion hea t transf er. See Modeling R adia tion (p.1489 ) for details ab out mo deling r adia tion hea t transf er. 3269Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageOff disables the c alcula tion of r adia tion hea t transf er. Rosseland enables the R osseland r adia tion mo del. P1 enables the P-1 r adia tion mo del. Discr ete Transf er (DTRM) enables the discr ete transf er radia tion mo del (DTRM). Surface to Surface (S2S) enables the sur face-to-sur face (S2S) r adia tion mo del. Discr ete Or dina tes (DO) enables the discr ete or dina tes (DO) r adia tion mo del. Monte Carlo (MC) enables the M onte Carlo (MC) r adia tion mo del. DO/E nergy Coupling allows you t o couple the ener gy and DO in tensit y equa tions a t each c ell, solving them simultaneously . See Defining N on-G ray Radia tion f or the DO M odel (p.1510 ) for details . Iteration P aramet ers contains par amet ers r elated t o the DTRM, S2S, and the DO mo dels .This p ortion of the dialo g box will app ear only if Discr ete Transf er (DTRM) ,Surface to Surface (S2S) , or Discr ete Or dina tes (DO) is selec ted as the Model. Energy Iterations p er R adia tion I teration controls the fr equenc y with which the r adia tion t erms ar e up dated as the c ontinuous phase solution proceeds .The Energy Iterations p er R adia tion I teration par amet er is set t o 10 b y default. This implies that the r adia tion c alcula tion is p erformed onc e every 10 it erations of the solution pr ocess. Incr easing the numb er can sp eed the c alcula tion pr ocess, but ma y slo w overall c onvergenc e. Maximum N umb er of R adia tion I terations controls the maximum numb er of it erations of the r adia tion c alcula tion dur ing each global it eration. The default setting of 5 means tha t the r adiosit y will b e up dated up t o 5 times .The ac tual numb er of iterations will b e less if the r esidual c onvergenc e criterion is e xceeded a t an y point dur ing these it er- ations . This it em app ears only when Discr ete Transf er or Surface to Surface is selec ted as the Model. Residual C onvergenc e Criteria determines when the r adia tion in tensit y up date is c onverged . It is defined as the maximum nor maliz ed change in the sur face intensit y from one r adia tion it eration t o the ne xt (see Equa tion 13.9 (p.1535 )). This it em app ears only when Discr ete Transf er or Surface to Surface is selec ted as the Model. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3270Task P age R eference GuideTarget N umb er of Hist ories determines the numb er of phot on hist ories t o be tracked f or the M onte Carlo simula tion. Too small of a numb er will pr oduce "sp eckled" r esults . Incr easing the tar get numb er of hist ories pr oduces a smo other and mor e accur ate solution, but a t the e xpense of higher c omputa tion eff ort. This it em app ears only when Monte Carlo is selec ted. View Factors and C lust ering contains par amet ers r elated t o the S2S mo del. This p ortion of the dialo g box will app ear only if Surface to Surface is selec ted as the Model. See Setting U p the S2S M odel (p.1495 ) for mor e inf ormation ab out the use of these par amet ers. Settings ... opens the View F actors and C lustering D ialog Box (p.3273 ), in which y ou c an set par amet ers r elated to sur face clust ers and view fac tors. Comput e/W rite/Read ... allows you t o comput e the view fac tors, write the c omput ed view fac tors t o a file , and r ead the file into ANSY S Fluen t.When y ou click Comput e/W rite/Read ...,The S elec t File D ialog Box (p.569) will open so tha t you c an sp ecify a name f or the file wher e ANSY S Fluen t should sa ve the view fac tors after computing them, and indic ate whether the files should b e sa ved in binar y format. Read E xisting F ile... opens The S elec t File D ialog Box (p.569), in which y ou c an sp ecify the file fr om which ANSY S Flu- ent should r ead view fac tors. Angular D iscr etiza tion contains par amet ers f or angular discr etiza tion and pix elation f or the DO mo del. This p ortion of the dialo g box will app ear only if Discr ete Or dina tes is selec ted as the Model. See Setting U p the DO M odel (p.1509 ) for mor e inf ormation ab out the use of these par amet ers. Theta D ivisions , Phi D ivisions define the numb er of c ontrol angles used t o discr etize each o ctant of the angular spac e (see Fig- ure 5.3: Angular C oordina te System in the Theor y Guide ). Theta P ixels, Phi P ixels are used t o control the pix elation tha t acc oun ts for an y control volume o verhang (see Figur e 5.7: Pixela- tion of C ontrol A ngle in the Theor y Guide and the figur es and discussion pr eceding it). Radia tion M esh Options This p ortion of the dialo g box will app ear only if the Monte Carlo mo del is selec ted. Target C ells P er Volume C lust er Coarsens the r adia tion mesh used b y the MC mo del. See Setting U p the MC M odel (p.1512 ) for mor e information ab out the use of this par amet er. Non-G ray M odel contains par amet ers r elated t o the non-gr ay P-1, DO, or MC mo del. This p ortion of the dialo g box will app ear only if P1,Discr ete Or dina tes, or Monte Carlo is selec ted as the Model. See Setting U p the P-1 Model with N on-G ray Radia tion (p.1491 ),Defining N on-G ray Radia tion f or the DO M odel (p.1510 ), or Setting Up the MC M odel (p.1512 ) for mor e inf ormation ab out the use of these par amet ers. Numb er of B ands specifies the numb er of bands f or the non-gr ay radia tion. 3271Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageWavelength In tervals (n=1) contains inputs tha t define each w avelength band . (It app ears only when the Numb er of B ands is nonz ero.) For each band , you c an sp ecify a Name , as w ell as the Start and End wavelength of the band in m. Note tha t the w avelength bands ar e sp ecified f or v acuum ( ). ANSY S Fluen t will automa tically acc oun t for the r efractive inde x in setting band limits f or media with diff erent from unit y. Solar L oad contains par amet ers r elated t o solar load mo del tha t can b e used t o calcula te radia tion eff ects fr om the sun’s rays tha t en ter a c omputa tional domain. It is a vailable only f or the 3D v ersion of ANSY S Fluen t. See Solar L oad M odel (p.1540 ) for mor e inf ormation ab out the use of these par amet ers. Model indic ates which mo del is used t o calcula te radia tion eff ects. Off disables the c alcula tion of solar r adia tions . Solar R ay Tracing enables the solar r ay tracing algor ithm DO Ir radia tion enables the DO ir radia tion option. Selec t Discr ete Or dina tes under Model before selec ting this option. Solar C alcula tor opens the Solar C alcula tor D ialog Box (p.3277 ). Sun D irection Vector contains the c omp onen ts of sun dir ection v ector. X,Y, Z are the c omp onen ts of the sun dir ection v ector. Use D irection C omput ed fr om S olar C alcula tor enables the use of dir ection v ector comput ed fr om the solar c alcula tor. Illumina tion P aramet ers contains illumina tion options . Direct Solar Ir radia tion is the amoun t of ener gy per unit ar ea due t o dir ect solar ir radia tion. Diffuse S olar Ir radia tion is the amoun t of ener gy per unit ar ea due t o diffuse solar ir radia tion. Spectral F raction is the fr action of inciden t solar r adia tion in the visible par t of the solar r adia tion sp ectrum. The sp ectral fraction is not used f or DO ir radia tion sinc e the DO implemen tation is in tended only f or a single band . This par amet er is a vailable only f or Solar R ay Tracing . Update Paramet ers contains up date par amet ers f or tr ansien t simula tions . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3272Task P age R eference GuideTime S teps p er S olar L oad U pdate specifies the numb er of time st eps tha t will dir ect the ANSY S Fluen t solv er to up date the solar load data for the sp ecified flo w-time in tervals in the unst eady solution pr ocess. 47.4.5. View Factors and C lust ering D ialo g Box The View F actors and C lust ering dialo g box allo ws you t o set par amet ers r elated t o sur face clust ers and view fac tors f or the sur face-to-sur face radia tion mo del. See Setting U p the S2S M odel (p.1495 ) for information ab out using this dialo g box. Controls Clust ering contains the metho ds and settings f or cr eating sur face clust ers. See Forming Sur face Clusters (p.1498 ) for information ab out sur face clust er settings . 3273Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageOptions gives y ou a choic e of f orming clust ers either manually or aut oma tically. Manual allows you t o form clust ers manually . Automa tic allows ANSY S Fluen t to form the clust er aut oma tically. Manual (available only when the Manual option is enabled) allo ws you t o set the fac es p er sur face clust er (FPSC) v alue f or w alls and inlet and outlet b oundar ies. Faces p er S urface Clust er for F low B oundar y Zones specifies the numb er of fac es in each sur face clust er for inlet and outlet b oundar ies (tha t is, exhaust fan, inlet v ent, intake fan, outlet v ent, mass-flo w inlet , mass-flo w outlet , pressur e far-field , pressur e inlet , pressur e outlet , outflo w, and v elocity inlet b oundar ies). This FPSC value c an also b e applied t o all w alls tha t are adjac ent to fluid z ones b y click ing the Apply to A ll Walls butt on.The default is set t o 1. See Clustering in the Theor y Guide for details about clust ering. Apply t o All Walls applies the v alue sp ecified in the Faces p er S urface Clust er for F low B oundar y Zones field t o all w alls tha t are adjac ent to fluid z ones . Automa tic (available only when the Automa tic option is enabled) allo ws you t o assign diff erent fac es p er sur face clust er (FPSC) v alues t o the w alls aut oma tically, based on the distanc e of the w alls fr om and the FPSC values of the w alls tha t are defined as cr itical. Maximum F aces p er S urface Clust er specifies the maximum numb er of fac es p er sur face clust er aut oma tically assigned t o non-cr itical wall z ones adjac ent to fluid z ones .The default is set t o 10. Comput e results in ANSY S Fluen t aut oma tically c alcula ting and up dating the fac e per sur face clust er values in the b oundar y conditions dialo g box for non-cr itical w all z ones adjac ent to fluid z ones , without computing the clust ers. View Factors contains settings f or computing the view fac tors. See Setting U p the View F actor C alcula tion (p.1501 ) for information ab out view fac tor calcula tion settings . Basis specifies ho w sur faces ar e defined f or the c alcula tion of view fac tors. See Selec ting the B asis f or Computing View F actors (p.1501 ) for mor e inf ormation. Face to Face specifies tha t the sur faces used t o calcula te the view fac tors ar e the b oundar y fac es. Clust er to Clust er specifies tha t the sur faces used t o calcula te the view fac tors ar e the clust ers defined b y the settings in the Clust ering group b ox.The clust er to clust er basis is only a vailable f or 3D c ases . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3274Task P age R eference GuideSurfaces specifies the geometr ic or ientation of sur face pairs with r espect to each other when using the hemicub e metho d. Blocking specifies tha t the view fac tor calcula tion acc oun ts for sur faces tha t blo ck the view s between the surfaces under c onsider ation. Nonblo cking specifies tha t the view fac tor calcula tion do es not acc oun t for sur faces tha t blo ck the view s between the sur faces under c onsider ation. Metho d specifies the metho d for computing the view fac tors. See Selec ting the M etho d for C omputing View Factors (p.1502 ) for inf ormation ab out cho osing a metho d. Hemicub e specifies the use of the hemicub e metho d for computing the view fac tors.The hemicub e metho d is available only f or 3D and axisymmetr ic cases , and should not b e used if an y of the z ones ar e defined as p eriodic or symmetr y boundar ies. Ray Tracing specifies the use of the r ay tracing metho d for computing the view fac tors. For 2D c ases , the numb er of r ays used with this metho d is t wo times the v alue set f or Resolution in the Paramet ers group b ox; for 3D c ases , the numb er of r ays is thr ee times the squar e of the Resolution value . Paramet ers contains settings r elated t o the hemicub e and r ay tracing metho ds for computing the view fac tors. All of these inputs ar e available when Hemicub e is selec ted under Metho d, wher eas only Resolution is available when Ray Tracing is selec ted. See Selec ting the M etho d for C omputing View F actors (p.1502 ) for inf ormation ab out setting the metho d par amet ers. Resolution specifies the r esolution of the hemicub e.The default v alue is set t o 10.You c an incr ease the v alue to reduc e aliasing eff ects tha t can lead t o overestima ted or under estima ted view fac tors. Subdivisions specifies the numb er of subfac es in to which each fac e is divided .The default v alue is set t o 5. This par amet er is only a vailable when the hemicub e metho d is used in c onjunc tion with the fac e to fac e basis . Normaliz ed S epar ation D istanc e specifies the r atio of the minimum fac e separ ation t o the eff ective diamet er of the fac e.The default value is set t o 5.This par amet er is only a vailable f or the hemicub e metho d. Zones P articipa ting in View Factor C alcula tion allows you t o define which b oundar y zones par ticipa te in the view fac tor calcula tion. See Specifying Boundar y Zone P articipa tion (p.1503 ) for mor e inf ormation. Selec t... opens the Participa ting B oundar y Zones D ialog Box (p.3276 ), wher e you c an define which b oundar y zones par ticipa te in the view fac tor calcula tion. 3275Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P age47.4.6. Participa ting B oundar y Zones D ialo g Box The Participa ting B oundar y Zones dialo g box allo ws you t o define which b oundar y zones par ticipa te in the view fac tor c alcula tion, to displa y zones in the gr aphics windo w, and set the t emp erature of zones tha t do not par ticipa te in the view fac tor c alcula tion. See Specifying B oundar y Zone P articipa- tion (p.1503 ) for details .This dialo g box op ens when y ou click the Selec t... butt on ne xt to the Zones Participa ting in View F actor C alcula tion lab el in the View F actors and C lust ering dialo g box. Controls Maximum D istanc e from C ritical Z one allows you t o view the maximum distanc e between cr itical zones and other z ones , and set all b oundar y zones tha t are located b eyond a c ertain distanc e from a cr itical zone as not par ticipa ting in the view fac tor calcula tion. To All O ther Z ones displa ys the maximum of the distanc es b etween the c entroids of cr itical and all other w all, inlet , and exit z ones when the Comput e butt on is click ed.This field is not editable .This is only a vailable when using the Automa tic option f or clust ering. Comput e calcula tes the distanc es b etween the c entroids of cr itical zones and all the other w all, inlet , and e xit zones and displa ys the maximum v alue in the To All O ther Z ones field and the To Participa ting Zones text-en try box. It requir es the definition of the cr itical zone . To Participa ting Z ones displa ys the maximum of the distanc es b etween the c entroids of cr itical and all other w all, inlet , and exit z ones when the Comput e butt on is click ed. Unlike the To All O ther Z ones field , you c an edit this t ext-en try box.You c an sp ecify the maximum distanc e allo wed b etween the c entroids of cr itical zones and all other w all, inlet , or e xit z ones tha t par ticipa te in the view fac tor calcula tion; when y ou click the Apply butt on, all of the z ones will b e mar ked as either par ticipa ting or not par ticipa ting , Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3276Task P age R eference Guideaccording t o the distanc e criteria you sp ecified . Note tha t this field is only a vailable when using the Automa tic option f or clust ering. Apply mar ks all of the w all, inlet , and e xit z ones as either par ticipa ting or not par ticipa ting in the view fac tor calcula tion, dep ending on whether the distanc e from their c entroid t o the c entroid of a cr itical zone is equal t o or less than v alue en tered f or To Participa ting Z ones .The Participa ting B oundar y Zones and Non-P articipa ting B oundar y Zones lists will b e up dated acc ordingly . Participa ting B oundar y Zones shows all the z ones tha t are par ticipa ting in the view fac tor calcula tion. You c an selec t a z one and click the ar row butt on tha t points to the r ight to mo ve the z one t o the Non-P articipa ting B oundar y Zones list. Non-P articipa ting B oundar y Zones shows all the z ones tha t are not par ticipa ting in the view fac tor calcula tion. You c an selec t a z one and click the ar row butt on tha t points to the lef t to mo ve the z one t o the Participa ting B oundar y Zones list. Displa y Zones displa ys an y zones selec ted in the Participa ting B oundar y Zones and Non-P articipa ting B oundar y Zones lists in the gr aphics windo w. Non-P articipa ting B oundar y Zones Temp erature allows you t o sp ecify the t emp erature of the z ones tha t do not par ticipa te in the view fac tor calcula tion. 47.4.7. Solar C alcula tor D ialo g Box The Solar C alcula tor dialo g box allo ws you t o set par amet ers r elated t o the c alcula tion of solar load models . See Solar L oad M odel (p.1540 ) for details .This dialo g box op ens when y ou click the Solar C al- cula tor... butt on in the Radia tion M odel dialo g box. Controls Global P osition contains the par amet ers t o define the p osition of solar r adia tion. 3277Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageLongitude specifies the longitude of the desir ed lo cation in degr ees.Values ma y range fr om to , wher e nega tive values indic ate the Western hemispher e and p ositiv e values indic ate the E astern hemispher e. Latitude specifies the la titude of the desir ed lo cation in degr ees.Values ma y range fr om (South p ole) t o (North p ole) with defined as the equa tor. Time zone specifies the lo cal time z one of the desir ed lo cation in hours r elative to Greenwich M ean Time (+- GMT ).This in teger v alue c an r ange fr om to . Starting D ate and Time contains par amet ers t o sp ecify da te and time . Day of Year contains par amet ers t o sp ecify da y and mon th. Time of D ay contains par amet ers t o sp ecify hour and minut es. Mesh Or ientation specifies the or ientation as the v ectors f or N orth and E ast in the CFD gr id sy stem of c oordina tes. Solar Ir radia tion M etho d contains par amet ers t o cho ose the solar ir radia tion metho d. Theor etic al M aximum enables theor etically maximum solar ir radia tion metho d. Fair Weather C onditions enables fair w eather c ondition solar ir radia tion metho d. Sunshine F actor is a linear r educ tion fac tor for the c omput ed inciden t load tha t allo ws for cloud c over to be acc oun ted for, if appr opriate. 47.4.8. Heat Exchanger M odel D ialo g Box The Heat Exchanger M odel dialo g box allo ws you t o define a hea t exchanger as par t of y our mo del. See Modeling H eat Exchangers (p.1573 ) for details ab out using the it ems b elow. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3278Task P age R eference GuideControls Options contains options r elated t o the hea t exchanger mo del. See Choosing a H eat Exchanger M odel (p.1574 ) for details ab out the diff erences b etween the mo dels asso ciated with these options . Dual C ell M odel allows you t o enable or disable the D ual C ell hea t exchanger mo del. When this option is enabled , the corresponding Define ... butt on op ens the Dual C ell H eat Exchanger D ialog Box (p.3279 ). Ungr oup ed M acro M odel allows you t o enable or disable the U ngroup ed M acro hea t exchanger mo del. When this option is enabled , the c orresponding Define ... butt on op ens the Ungroup ed M acro Heat Exchanger D ialog Box (p.3285 ). Macro M odel G roup allows you t o enable or disable the M acro hea t exchanger gr oup mo del. When this option is enabled , the c orresponding Define ... butt on op ens the Macro Heat Exchanger G roup D ialog Box (p.3291 ). 47.4.9. Dual C ell H eat Exchanger D ialo g Box The Dual C ell H eat Exchanger dialo g box allo ws you t o use the NTU metho d for hea t transf er calcu- lations .This mo del allo ws the solution of auxiliar y flo w on a separ ate mesh (other than the pr imar y fluid mesh). See Using the D ual C ell H eat Exchanger M odel (p.1576 ) for inf ormation ab out using this dialo g box. Controls Heat Exchanger contains a list of pr edefined hea t exchangers . New... opens the Set D ual C ell H eat Exchanger D ialog Box (p.3280 ). 3279Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageCopy opens the Copy From D ialog Box (p.3284 ), which allo ws you t o copy the cur rently selec ted hea t exchanger . Delet e remo ves the cur rently selec ted hea t exchanger . Modify ... opens the Set D ual C ell H eat Exchanger D ialog Box (p.3280 ). 47.4.10. Set D ual C ell H eat Exchanger D ialo g Box The Set D ual C ell H eat Exchanger dialo g box allo ws you t o define the hea t exchanger par amet ers. See Using the D ual C ell H eat Exchanger M odel (p.1576 ) for details ab out using this dialo g box. Controls Name allows you t o sp ecify a name f or the dual c ell hea t exchanger . Fluid Z ones allows you t o sp ecify the fluid z one par amet ers f or the hea t exchanger . Numb er of P asses specifies the numb er of passes f or the hea t exchanger . Primar y Fluid Z one allows you t o sp ecify the fluid of the pr imar y fluid z one f or the hea t exchanger . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3280Task P age R eference GuideAuxiliar y Fluid Z one allows you t o sp ecify the fluid f or the auxiliar y fluid z one , per pass . Imp ortant The selec ted z ones must b e overlapping in ph ysical spac e. Heat Rejec tion contains par amet ers sp ecific t o the r ejec tion of hea t in the hea t exchanger . Options allows you t o sp ecify ho w the hea t rejec tion in the hea t exchanger is c omput ed. Fixed H eat Rejec tion allows you t o sp ecify hea t rejec tion par amet ers. Fixed Inlet Temp erature allows you t o use t otal hea t rejec tion as the desir ed output. Heat Rejec tion Targeted allows you t o sp ecify the hea t rejec tion desir ed fr om the hea t exchanger (a vailable only when the Fixed H eat Rejec tion option is enabled). Inlet Z one f or Temp erature Updates allows ANSY S Fluen t to change the t emp erature of the sp ecified inlet z one in or der t o ma tch the targeted hea t rejec tion (a vailable only when the Fixed H eat Rejec tion option is enabled). Temp erature Update Under-Relaxa tion controls c onvergenc e (available only when the Fixed H eat Rejec tion option is enabled). Iteration In terval B etween Temp erature Updates controls div ergenc e (available only when the Fixed H eat Rejec tion option is enabled). Performanc e Data contains par amet ers f or sp ecifying the hea t exchanger ’s performanc e da ta. Options allows you t o cho ose b etween using r aw performanc e da ta or NTU p erformanc e da ta. Raw D ata allows you t o sp ecify r aw performanc e da ta for the hea t exchanger . NTU D ata allows you t o sp ecify NTU p erformanc e da ta for the hea t exchanger . Heat Exchanger P erformanc e Data contains par amet ers c oncerning the hea t exchanger ’s performanc e da ta. NTU Table opens the NTU Table D ialog Box (p.3284 ) (available only when the NTU D ata option is enabled). Heat Transf er Table opens the Heat Transf er D ata Table D ialog Box (p.3282 ) (available only when the Raw D ata option is enabled). 3281Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageEffectiveness-NTU Rela tion comput es the NTU v alues fr om the hea t transf er da ta. Choose cross-flo w-unmix ed,parallel- flow, or coun ter-flo w, all of which ar e descr ibed in NTU R elations (available only when the Raw Data option is enabled). Referenc e Inlet Temp erature allows you t o sp ecify the inlet r eference temp erature for the pr imar y and the auxiliar y fluids . (Available only when the Raw D ata option is enabled .) Frontal A rea allows you t o sp ecify the fr ontal ar ea for the hea t exchanger . Primar y Fluid allows you t o sp ecify a v alue f or the Core Frontal A rea for the pr imar y fluid , or t o comput e the v alue from a sur face zone using the Comput e From drop-do wn list. Auxiliar y Fluid allows you t o sp ecify a v alue f or the Core Frontal A rea for the auxiliar y fluid , or t o comput e the v alue from a sur face zone using the Comput e From drop-do wn list. Coupling specifies par amet ers when y ou w ant to couple the hea t exchanger passes . Temp erature specifies , by default , the mass-w eigh ted a verage f or the t emp erature of the outlet of P ass 1 t o the inlet of P ass 2. Similar ly, the mass-w eigh ted-a verage t emp erature of the outlet of P ass 2 will b e applied at the inlet z one of P ass 3, and so on. (Available only when multiple passes ar e sp ecified in the Fluid Zones tab .) Plot NTU plots the p erformanc e da ta cur ve for the selec ted hea t exchanger .The p erformanc e da ta is supplied through the Performanc e Data tab . 47.4.11. Heat Transf er D ata Table D ialo g Box The Heat Transf er D ata Table dialo g box contains inf ormation on the numb er of fluid flo w rates and heat transf er da ta for the pr imar y and auxiliar y fluids . See Using the U ngroup ed M acro Heat Exchanger Model (p.1586 ) for details ab out using this dialo g box. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3282Task P age R eference GuideControls Numb er of A uxiliar y Fluid F low R ates sets the numb er of auxiliar y fluid flo w rates. Numb er of P rimar y Fluid F low R ates sets the numb er of pr imar y fluid flo w rates. Auxiliar y Fluid F low R ate sets fluid flo w rates for the auxiliar y fluid . Primar y Fluid F low R ate sets fluid flo w rates for the pr imar y fluid . Heat Transf er sets the hea t transf er for the c orresponding pr imar y and auxiliar y fluid flo w rates. Read ... allows you t o read in a file c ontaining hea t transf er da ta. Write... allows you t o wr ite a file c ontaining hea t transf er da ta. 3283Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P age47.4.12. NTU Table D ialo g Box The NTU Table dialo g box contains inf ormation on the numb er of fluid flo w rates and NTU da ta for the pr imar y and auxiliar y fluids . See Using the U ngroup ed M acro Heat Exchanger M odel (p.1586 ) for details ab out using this dialo g box. Controls Numb er of A uxiliar y Fluid F low R ates sets the numb er of auxiliar y fluid flo w rates. Numb er of P rimar y Fluid F low R ates sets the numb er of pr imar y fluid flo w rates. Auxiliar y Fluid F low R ate sets fluid flo w rates for the auxiliar y fluid . Primar y Fluid F low R ate sets fluid flo w rates for the pr imar y fluid . NTU sets the NTU v alues f or the c orresponding pr imar y and auxiliar y fluid flo w rates. Read ... allows you t o read in a file c ontaining NTU da ta. Write... allows you t o wr ite a file c ontaining NTU da ta. 47.4.13. Copy From D ialo g Box The Copy From dialo g box allo ws you t o copy the setup of one hea t exchanger t o another . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3284Task P age R eference GuideControls Existing H eat Exchangers contains a list of hea t exchangers , from which y ou c an c opy the settings fr om one hea t exchanger t o another . 47.4.14. Ungr oup ed M acro Heat Exchanger D ialo g Box The Ungr oup ed M acro H eat Exchanger dialo g box allo ws you t o set up the ungr oup ed macr o hea t exchanger mo del. See Using the U ngroup ed M acro Heat Exchanger M odel (p.1586 ) for details ab out using this dialo g box. 3285Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageControls Fluid Z one specifies the z one tha t represen ts the hea t exchanger . Model D ata contains the par amet ers r elated t o the hea t exchanger mo del. Options allows you t o cho ose one of the f ollowing settings: Fixed H eat Rejec tion specifies tha t ANSY S Fluen t should c omput e the auxiliar y fluid inlet t emp erature for a sp ecified heat rejec tion. Fixed Inlet Temp erature specifies tha t ANSY S Fluen t should c omput e the t otal hea t rejec tion of the c ore for a giv en inlet auxiliar y temp erature. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3286Task P age R eference GuideHeat Transf er M odel allows you t o sp ecify either the ntu-mo del or the simple-eff ectiveness-mo del for hea t transf er. See Choosing a H eat Exchanger M odel (p.1574 ) for inf ormation on the diff erences b etween these mo dels . Core Porosit y M odel contains a dr op-do wn list of all a vailable c ore porosity mo dels . Edit... opens the Core Porosity Model D ialog Box (p.3289 ). Heat Exchanger P erformanc e Data contains the par amet ers f or hea t transf er. Heat Transf er D ata... opens the Heat Transf er D ata Table D ialog Box (p.3282 ).This it em will app ear f or the NTU mo del only . Auxiliar y Fluid Temp erature specifies the auxiliar y fluid t emp erature.This it em will app ear only f or the NTU mo del. Primar y Fluid Temp erature specifies the gas str eam t emp erature.This it em will app ear only f or the NTU mo del. Velocity Effectiveness C urve... opens the Velocity Effectiveness C urve Dialog Box (p.3289 ) in which y ou c an define the eff ectiveness of the hea t exchanger c ore ( in Equa tion 6.11 in the Theor y Guide ).This it em will app ear f or simple eff ectiveness mo del only . Geometr y contains par amet ers t o define the macr o gr id. Width sets the width of the hea t exchanger c ore.The Width is measur ed in the pass-t o-pass dir ection. Heigh t sets the heigh t of the hea t exchanger c ore.The Heigh t is measur ed in the auxiliar y fluid inlet dir ection. Depth sets the depth of the hea t exchanger c ore. Numb er of P asses specifies the numb er of passes f or the macr o gr id. (See Figur e 14.17: 1x4x3 M acros (p.1594 ).) Numb er of Ro ws/Pass, Numb er of C olumns/P ass specify the numb er of macr o rows and c olumns p er pass in the macr o gr id. (See Figur e 14.17: 1x4x3 Macros (p.1594 ).) View P asses displa ys the macr o gr id. (This butt on b ecomes a vailable af ter you click Apply .) The pa th of the auxil- iary fluid is c olor-c oded in the displa y: macr o is red and macr o is blue . Draw M esh toggles b etween displa ying and not displa ying the mesh when the macr o mesh is displa yed (using the View P asses butt on). The Mesh D ispla y Dialog Box (p.3239 ) opens when Draw M esh is selec ted. 3287Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageUpdate from P lane Tool updates the Auxiliar y Fluid Inlet D irection and Pass-t o-Pass D irection from the plane t ool or ient- ation. The Width ,Heigh t, and Depth will also b e up dated. See Using the P lane Tool (p.2744 ) for inf orm- ation ab out using the plane t ool. Auxiliar y Fluid Inlet D irection (heigh t) specifies the dir ection in which the auxiliar y fluid en ters the hea t exchanger . See Figur e 14.17: 1x4x3 Macros (p.1594 ). Pass-t o-Pass D irection (width) specifies the dir ection in which the auxiliar y fluid mo ves a t the end of each pass thr ough the hea t exchanger . See Figur e 14.17: 1x4x3 M acros (p.1594 ). Auxiliar y Fluid contains the option t o sp ecify the auxiliar y fluid pr operties. Auxiliar y Fluid P roperties M etho d contains options f or sp ecifying auxiliar y fluid pr operties. constan t-sp ecific-hea t allows you t o sp ecific a c onstan t value f or the auxiliar y fluid sp ecific hea t. user-defined-en thalp y allows you t o sp ecify a user-defined func tion f or the auxiliar y fluid en thalp y. Auxiliar y Fluid S pecific H eat specifies the v alue of in Equa tion 6.17 in the Theor y Guide .This v alue is sp ecified only if constan t-sp ecific-hea t is selec ted. Auxiliar y Fluid E nthalp y UDF allows you t o sp ecify a user-defined func tion f or the auxiliar y fluid en thalp y (see Equa tion 6.17 in the Theor y Guide ).This option is a vailable only when user-defined-en thalp y is selec ted. Auxiliar y Fluid F low R ate sets the flo w rate of the auxiliar y fluid ( in Equa tion 6.16 in the Theor y Guide ). Heat Rejec tion sets the t otal hea t rejec tion ( in Equa tion 6.15 in the Theor y Guide ).This v alue is sp ecified only if Fixed H eat Rejec tion is selec ted. Initial Temp erature sets an initial guess f or the inlet t emp erature ( in Equa tion 6.11 and Equa tion 6.16 in the Theor y Guide ).This v alue is sp ecified only if Fixed H eat Rejec tion is selec ted. Inlet Temp erature sets the auxiliar y fluid initial t emp erature ( in Equa tion 6.11 and Equa tion 6.16 in the Theor y Guide ). This v alue is sp ecified only if Fixed Inlet Temp erature is selec ted in the Model D ata tab . Inlet P ressur e sets the auxiliar y fluid inlet pr essur e.This v alue is sp ecified only if user-defined-en thalp y is selec ted. Inlet Q ualit y specifies the v alue of in Equa tion 6.20 in the Theor y Guide .This v alue is sp ecified only if user- defined-en thalp y is selec ted. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3288Task P age R eference GuidePressur e Drop specifies the v alue of in Equa tion 6.21 in the Theor y Guide .This v alue is sp ecified only if user- defined-en thalp y is selec ted. Apply saves all the settings f or the hea t exchanger sp ecified in the Fluid Z one list. Delet e delet es the hea t exchanger sp ecified in the Fluid Z one list. 47.4.15. Velocity Effectiveness C urve Dialo g Box The Velocity Effectiveness C urve dialo g box allo ws you t o define eff ectiveness cur ve. It is op ened by click ing Velocity Effectiveness C urve... in the Ungroup ed M acro Heat Exchanger D ialog Box (p.3285 ). Controls Numb er of P oints specifies the numb er of da ta pairs in the eff ectiveness pr ofile .The default v alue of 1 indic ates a c onstan t effectiveness . Velocity, Effectiveness specify the da ta pairs f or the eff ectiveness pr ofile .These it ems ar e available only if the simple eff ective model has b een selec ted. Note tha t the Effectiveness values must b e within the r ange of 0–1. 47.4.16. Core Porosit y M odel D ialo g Box The Core Porosit y M odel dialo g box allo ws you t o mo dify or define a hea t exchanger c ore mo del. This dialo g box op ens when y ou click Edit... in the Ungroup ed M acro Heat Exchanger D ialog Box (p.3285 ). 3289Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageControls Name specifies the name of a new hea t exchanger c ore mo del. Database contains a dr op-do wn list of all hea t exchanger c ore mo dels tha t are cur rently a vailable . Gas-S ide P ressur e Drop contains par amet ers tha t define the air-side pr essur e dr op. Minimum F low to Face Area R atio sets the v alue of in Equa tion 6.2 in the Theor y Guide . Entranc e Loss C oefficien t sets the v alue of in Equa tion 6.2 in the Theor y Guide . Exit L oss C oefficien t sets the v alue of in Equa tion 6.2 in the Theor y Guide . Gas S ide S urface Area sets the v alue of in Equa tion 6.2 in the Theor y Guide . Minimum C ross S ection F low A rea sets the v alue of in Equa tion 6.2 in the Theor y Guide . Core Friction C oefficien t sets the v alue of in Equa tion 6.3 in the Theor y Guide . Core Friction E xponen t sets the v alue of in Equa tion 6.3 in the Theor y Guide . Change/C reate saves the settings in the dialo g box and adds the new mo del t o the Database list. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3290Task P age R eference GuideRead ... opens The S elec t File D ialog Box (p.569), in which y ou c an selec t an e xternal file c ontaining a pr edefined heat exchanger c ore mo del. 47.4.17. Macro Heat Exchanger G roup D ialo g Box The Macro H eat Exchanger G roup dialo g box allo ws you t o mo dify or define a hea t exchanger c ore group . Controls Name specifies the name of a new hea t exchanger gr oup . 3291Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageFluid Z ones contains a list of all the fluid z ones . HX G roups contains list of the hea t exchanger gr oups . Model D ata contains all the par amet ers t o be sp ecified f or the mo del. Primar y Fluid F low D irection gives y ou a choic e of gas flo w dir ection. Width, Heigh t, Depth specifies the width, heigh t and the depth of the gas flo w dir ection. Connec tivit y allows you t o define the upstr eam and do wnstr eam c onnec tions . Upstr eam specifies the upstr eam hea t exchanger gr oup . Downstr eam specifies the do wnstr eam hea t exchanger gr oup . Heat Transf er M odel allows you t o selec t either the simple-eff ectiveness-mo del or the ntu-mo del. See Choosing a H eat Exchanger M odel (p.1574 ) for inf ormation on the diff erences b etween these mo dels . Core Porosit y M odel specifies whether default v alues ar e chosen f or the c ore porosity mo del. Edit... opens the Core Porosity Model D ialog Box (p.3289 ) for the definition of a new c ore porosity mo del. Heat Exchanger P erformanc e Data contains the par amet ers f or hea t transf er. Heat Transf er D ata... opens the Heat Transf er D ata Table D ialog Box (p.3282 ).This dialo g box allo ws you t o define the heat transf er for diff erent primar y and auxiliar y fluid flo w rates.This it em will app ear f or the NTU model only . Velocity Effectiveness C urve... opens the Velocity Effectiveness C urve Dialog Box (p.3289 ) in which y ou c an define the eff ectiveness of the hea t exchanger c ore ( in Equa tion 6.11 in the Theor y Guide ).This it em will app ear f or simple eff ectiveness mo del only . Auxiliar y Fluid Temp erature specifies the auxiliar y fluid t emp erature.This it em will app ear f or the NTU mo del only . Primar y Fluid Temp erature specifies the gas str eam fluid t emp erature.This it em will app ear f or the NTU mo del only . Geometr y contains par amet ers t o define the macr o gr id. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3292Task P age R eference GuideWidth, Heigh t, Depth specifies the width, heigh t and the depth of the hea t exchanger . Numb er of P asses specifies the numb er of passes . Numb er of Ro ws/Pass specifies the numb er of r ows per pass . Numb er of C olumns/P ass specifies the numb er of c olumns p er pass . View P asses displa ys the macr o gr id. (This butt on b ecomes a vailable af ter you click Set.) The pa th of the auxiliar y fluid is c olor-c oded in the displa y: macr o is red and macr o is blue . Draw M esh toggles b etween displa ying and not displa ying the mesh when the macr o mesh is displa yed (using the View P asses butt on). The Mesh D ispla y Dialog Box (p.3239 ) opens when Draw M esh is selec ted. Update from P lane Tool updates the Auxiliar y Fluid Inlet D irection and Pass-t o-Pass D irection from the plane t ool or ient- ation. The Width ,Heigh t, and Depth will also b e up dated. See Using the P lane Tool (p.2744 ) for inf orm- ation ab out using the plane t ool. Auxiliar y Fluid Inlet D irection specifies the dir ection in which the auxiliar y fluid en ters the hea t exchanger . See Figur e 14.17: 1x4x3 Macros (p.1594 ). Pass-t o-Pass D irection specifies the dir ection in which the auxiliar y fluid mo ves a t the end of each pass thr ough the hea t exchanger . See Figur e 14.17: 1x4x3 M acros (p.1594 ). Auxiliar y Fluid contains inputs t o sp ecify the pr operties of the auxiliar y fluid . Properties M etho d specifies the metho d to sp ecify the auxiliar y fluid pr operties.You c an cho ose fr om constan t-sp ecific- hea t and user-defined-en thalp y. Specific H eat sets the sp ecific hea t of the auxiliar y fluid ( in Equa tion 6.16 you cho ose constan t-sp ecific-hea t. Enthalp y UDF sets the en thalp y as defined b y the user-defined func tion selec ted fr om the dr op-do wn list. Auxiliar y Fluid F low R ate sets the flo w rate of the auxiliar y fluid ( in Equa tion 6.16 in the Theor y Guide ). Initial Temp erature sets an initial guess f or the inlet t emp erature ( in Equa tion 6.11 and Equa tion 6.16 in the Theor y Guide ).This v alue is sp ecified only if Fixed H eat Rejec tion is selec ted. Inlet P ressur e sets the auxiliar y fluid inlet pr essur e.This v alue is sp ecified only if user-defined-en thalp y is selec ted. 3293Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageInlet Q ualit y specifies the v alue of in Equa tion 6.20 in the Theor y Guide . Pressur e Drop specifies the v alue of in Equa tion 6.21 in the Theor y Guide .This v alue is sp ecified only if user- defined-en thalp y is selec ted. Supplemen tary Auxiliar y Fluid S tream specifies pr operties of the supplemen tary auxiliar y str eam. Supplemen tary M ass F low R ate specifies the supplemen tary fluid flo w rate as constan t,polynomial or piec ewise-linear . Supplemen tary Flow Temp erature specifies the supplemen tary fluid t emp erature as constan t,polynomial or piec ewise-linear . Supplemen tary Flow Q ualit y specifies the supplemen tary fluid qualit y. Create saves all the settings in the dialo g box. Delet e delet es the gr oup tha t is selec ted in the HX G roups list. Replac e changes the par amet ers of the alr eady existing gr oup tha t is selec ted in the HX G roups list. Set... opens the Ungroup ed M acro Heat Exchanger D ialog Box (p.3285 ), in which y ou c an define a new hea t ex- changer c ore mo del or r ead one fr om an e xternal file . 47.4.18. Species M odel D ialo g Box The Species M odel dialo g box allo ws you t o set par amet ers r elated t o the c alcula tion of sp ecies transp ort and c ombustion. For details ab out the it ems b elow, see the f ollowing sec tions: •Enabling S pecies Transp ort and R eactions and C hoosing the M ixture Material (p.1616 ) •Manual Inputs f or Wall Sur face Reactions (p.1658 ) •User Inputs f or P article Sur face Reactions (p.1661 ) •Using the P remix ed C ombustion M odel (p.1749 ) •Using the P artially P remix ed C ombustion M odel (p.1759 ) •Steps f or U sing the C omp osition PDF Transp ort Model (p.1779 ) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3294Task P age R eference GuideControls Model indic ates which mo del, if an y, is used t o calcula te sp ecies tr ansp ort/combustion. Off disables sp ecies c alcula tions . 3295Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageSpecies Transp ort enables the c alcula tion of multi-sp ecies tr ansp ort (either non-r eacting or r eacting , dep ending on the selec tion f or Reac tions ). See Modeling S pecies Transp ort and F inite-Rate Chemistr y (p.1613 ) for details . Non-P remix ed C ombustion enables the c alcula tion of turbulen t reacting flo w using the non-pr emix ed c ombustion mo del. See Modeling N on-P remix ed C ombustion (p.1687 ) for details .This option is a vailable only f or turbulen t flows using the pr essur e-based solv er. Premix ed C ombustion enables the pr emix ed turbulen t combustion mo del. See Modeling P remix ed C ombustion (p.1749 ) for details .This option is a vailable only f or turbulen t flo ws using the pr essur e-based solv er. Partially P remix ed C ombustion enables the par tially pr emix ed turbulen t combustion mo del. See Modeling P artially P remix ed C om- bustion (p.1759 ) for details .This option is a vailable only f or turbulen t flo ws using the pr essur e-based solv er. Comp osition PDF Transp ort enables the c omp osition PDF tr ansp ort mo del. See Modeling a C omp osition PDF Transp ort Prob- lem (p.1779 ) for details .This option is a vailable only f or turbulen t flo ws using the pr essur e-based solv er. Reac tions contains options r elated t o the mo deling of r eacting flo w. (This sec tion of the dialo g box app ears only when Species Transp ort or Comp osition PDF Transp ort is the sp ecified Model.) Volumetr ic enables the c alcula tion of r eacting flo w using the finit e-rate formula tion. See Volumetr ic Reac- tions (p.1614 ) for details . Wall S urface enables the c alcula tion of w all sur face reactions . See Wall Sur face Reactions and C hemic al Vapor D e- position (p.1654 ) for details .This it em will app ear only if Volumetr ic is enabled . Particle S urface enables the c alcula tion of par ticle sur face reactions . See Particle Sur face Reactions (p.1661 ) for details . This it em will app ear only if Volumetr ic is enabled . Electrochemic al enables the c alcula tion of elec trochemic al reactions . See Electrochemic al Reactions (p.1663 ) for details . This it em will app ear only if Volumetr ic is enabled . Integration P aramet ers... is a c ommand butt on tha t op ens the Integration P aramet ers D ialog Box (p.3315 ).This butt on app ears for the sp ecies tr ansp ort mo del, when Volumetr ic is enabled under Reac tions and Stiff C hemistr y Solver is enabled under Options or when Eddy-D issipa tion C onc ept is enabled under Turbulenc e- Chemistr y In teraction . Wall S urface Reac tion Options contains additional options f or w all sur face reactions .This p ortion of the dialo g box app ears only if Wall Surface is enabled under Reac tions . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3296Task P age R eference GuideHeat of S urface Reac tions (if enabled) includes the hea t release due t o sur face reactions in the ener gy equa tion. You must r e- memb er to set appr opriate formation en thalpies (standar d sta te en thalpies) if y ou enable this option. Mass D eposition S our ce (if enabled) includes the eff ect of sur face mass tr ansf er in the c ontinuit y equa tion. Aggr essiv eness F actor is a numer ical fac tor tha t controls the r obustness and the c onvergenc e sp eed.This v alue r anges between 0 and 1, wher e 0 is the most r obust , but r esults in the slo west c onvergenc e.The default value f or the Aggr essiv eness F actor is 0.5. Chemistr y Solver is a dr op-do wn list in which y ou c an selec t the solv er for the chemic ally r eactive flo w simula tion. This item app ears only f or Species Transp ort and Comp osition PDF Transp ort mo dels in volving Volumetr ic reactions . Stiff C hemistr y Solver enables efficien t integration of stiff chemic al kinetics .This it em app ears only when Finit e-Rate/N o TCI or Eddy-D issipa tion C onc ept is selec ted in the Turbulenc e-Chemistr y In teraction group b ox. See Solution of S tiff C hemistr y Systems (p.1652 ) for details . CHEMKIN-CFD S olver enables the in tegration of chemic al kinetics using the ANSY S CHEMKIN-CFD S olver, designed f or lar ge, stiff chemistr y mechanisms .This it em app ears only when Finit e-Rate/N o TCI or Eddy-D issipa tion Conc ept is selec ted in the Turbulenc e-Chemistr y In teraction group b ox. Relax t o Chemic al E quilibr ium enables efficien t mo deling of chemic al kinetics eff ects based only on equilibr ium c alcula tion and as- sumptions ab out char acteristic timesc ales f or appr oaching equilibr ium. This it em is not a vailable f or the Eddy Dissipa tion C onc ept TCI option. (See The R elaxa tion t o Chemic al Equilibr ium M odel for details . None - E xplicit S our ce mak es e xplicit use of chemistr y sour ce terms in the sp ecies tr ansp ort equa tions , without a stiff- chemistr y solv er (not r ecommended f or stiff or c omple x chemistr y). Options contains additional options f or the Species Transp ort mo del and f or the Comp osition PDF Transp ort. (This sec tion will not app ear in the dialo g box for the other mo dels .) Inlet D iffusion includes the diffusion flux of sp ecies a t inlet. Diffusion E nergy Sour ce (if enabled) includes the eff ect of en thalp y transp ort due t o sp ecies diffusion in the ener gy equa tion. Full M ultic omp onen t Diffusion enables the full multic omp onen t diffusion mo del. See Full M ultic omp onen t Diffusion (p.1142 ) for details . Thermal D iffusion enables the ther mal diffusion mo del. See Thermal D iffusion C oefficien ts (p.1144 ) for details . 3297Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageLiquid M icro-M ixing is used t o mo del liquid r eactions .When the Liquid M icro-M ixing mo del is in voked, ANSY S Fluen t uses the volume-w eigh ted-mixing-la w formula t o calcula te the densit y. Species M igration (if enabled) includes the ion sp ecies migr ation t erm in the sp ecies tr ansp ort equa tion. This it em app ears only when Electrochemic al reactions ar e enabled . Thick ened F lame M odel enables the mo deling of laminar flames .This applic ation is t ypic ally used as an LES c ombustion model f or turbulen t premix ed and par tially-pr emix ed flames . Include Temp erature Fluctuations enables the c alcula tion of the multi-mo de ener gy equa tion. This option is a vailable when the c om- position PDF tr ansp ort mo del is selec ted. Mixture Properties contains c ontrols and inf ormation ab out the mix ture being mo deled .This sec tion of the dialo g box will not app ear if Premix ed C ombustion is the selec ted under Model. Mixture M aterial contains a dr op-do wn list of a vailable mix ture ma terials.When y ou first enable the Species Transp ort model, you c an cho ose fr om all of the mix ture ma terials defined in the da tabase , or y ou c an cho ose a “templa te” and define y our o wn ma terial. (Click View... to op en the Fluen t Database M aterials D ialog Box (p.3396 ) and check the pr operties of the mix ture ma terial selec ted in the list.) S ee Enabling S pecies Transp ort and R eactions and C hoosing the M ixture Material (p.1616 ) for details . When y ou use the Non-P remix ed C ombustion or Partially P remix ed C ombustion mo del, this list will b e inac tive.The mix ture ma terial for a non-pr emix ed or par tially pr emix ed c ombus- tion c alcula tion will b e det ermined fr om the c ontent of the PDF file gener ated in ANSY S Fluen t using the PDF Options par amet ers. Numb er of Volumetr ic Species specifies the numb er of gas-phase sp ecies in the selec ted Mixture M aterial.This is an inf ormational displa y only ; you c annot edit this v alue . Numb er of S olid S pecies specifies the numb er of solid sp ecies defined in the selec ted Mixture M aterial.This is an inf ormational displa y only ; you c annot edit this v alue . (This list will app ear only f or Species Transp ort mo dels in- volving Wall S urface reactions .) Numb er of S ite Species specifies the numb er of sit e sp ecies defined in the selec ted Mixture M aterial.This is an inf ormational displa y only ; you c annot edit this v alue . (This list will app ear only f or Species Transp ort mo dels in- volving Wall S urface reactions .) Turbulenc e-Chemistr y In teraction indic ates which mo del is t o be used f or turbulenc e-chemistr y interaction when the Species Transp ort model with Volumetr ic reactions is used . Finit e-Rate/N o TCI comput es only the A rrhenius r ate (see Equa tion 7.7 in the Theor y Guide ) and neglec ts turbulenc e- chemistr y interaction. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3298Task P age R eference GuideFinit e-Rate/Eddy-D issipa tion (for turbulen t flo ws) comput es b oth the A rrhenius r ate and the mixing r ate and uses the smaller of the t wo. Eddy-D issipa tion (for turbulen t flo ws) comput es only the mixing r ate (see Equa tion 7.25 and Equa tion 7.26 in the Theor y Guide ). Eddy-D issipa tion C onc ept (for turbulen t flo ws) mo dels turbulenc e-chemistr y interaction with detailed chemic al mechanisms (see Equa tion 7.25 and Equa tion 7.26 in the Theor y Guide ). Coal C alcula tor... opens the Coal C alcula tor D ialog Box (p.3312 ). Selec t Boundar y Species ... opens the Selec t Boundar y Species dialo g box (see Figur e 15.3: The S elec t Boundar y Species D ialog Box (p.1623 )). Selec t Rep orted Residuals opens the Selec t Residual M onit ored S pecies dialo g box (see Figur e 15.4: The S elec t Residual Monit ored S pecies (p.1624 )). Options contains par amet ers r elated t o the laminar finit e-rate or the edd y-dissipa tion c oncept mo del. This sec tion of the dialo g box will app ear when Finit e-Rate/N o TCI or the Eddy-D issipa tion C onc ept is selec ted f or Turbulenc e-Chemistr y In teraction . Flow Iterations P er C hemistr y Update (steady-sta te only) sp ecifies ho w of ten ANSY S Fluen t will up date the chemistr y dur ing the c alcula tion. Increasing the numb er can r educ e the c omputa tional e xpense of the chemistr y calcula tions .This option is not a vailable when the None - E xplicit S our ce option is selec ted f or Chemistr y Solver. Aggr essiv eness F actor (steady-sta te only) is a numer ical fac tor tha t controls the r obustness and the c onvergenc e sp eed.This value r anges b etween 0 and 1, wher e 0 is the most r obust , but r esults in the slo west c onvergenc e. The default v alue f or the Aggr essiv eness F actor is 0.5. This option is a vailable only when Stiff Chemistr y Solver or CHEMKIN CFD S olver is selec ted f or Chemistr y Solver. Temp erature Threshold (steady-sta te only) is the thr eshold f or cell temp erature below which the chemistr y reaction r ate in the c ell will b e set t o zero.This ma y impr ove the c omputa tional time without sacr ificing accur acy. The default v alue is 200 K. This option is a vailable only when Stiff C hemistr y Solver or CHEMKIN CFD S olver is selec ted f or Chemistr y Solver. Volume F raction C onstan t specifies the v alue of in Equa tion 7.28 in the Theor y Guide . Time Sc ale C onstan t specifies the v alue of in Equa tion 7.29 in the Theor y Guide . Thick ened F lame M odel Options contains par amet ers r elated t o the thick ened flame mo del. This gr oup b ox is displa yed only if the Thick ened F lame M odel is enabled in the Options group b ox. 3299Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageNumb er of G rid P oints in F lame by default ar e 8 gr id p oints. Integral L ength Sc ale is the r epresen tative of the lar gest edd y siz es, in Equa tion 7.35 in the Fluent Theor y Guide (typic ally, 1/4 t o 1/2 of a char acteristics dimension, such as a bur ner diamet er, an inlet diamet er, or a siz e of a bluff b ody).This it em is a vailable only f or simula tions with the Lar ge E ddy Simula tion (LES) turbulenc e model. PDF Options contains options r elated f or the non-pr emix ed c ombustion mo del. (This sec tion will app ear only if Non- Premix ed C ombustion or Partially-P remix ed C ombustion is the selec ted Model.) Inlet D iffusion includes the diffusion flux of sp ecies a t inlet. Compr essibilit y Effects can b e enabled t o acc oun t for cases wher e substan tial pr essur e changes o ccur in time and/or spac e when mo deling a non-adiaba tic sy stem. See Specifying the Op erating P ressur e for the S ystem (p.1693 ) for details . Liquid M icro-M ixing is used t o mo del liquid r eactions .When the Liquid M icro-M ixing mo del is in voked, ANSY S Fluen t uses the volume-w eigh ted-mixing-la w formula t o calcula te the densit y. Probabilit y Densit y Func tion is a dr op-do wn list tha t allo ws you t o cho ose b etween the shap e of the assumed pr obabilit y densit y func tion (PDF): •double delta : as giv en b y Equa tion 8.21 in the Fluent Theor y Guide . •beta: as giv en b y Equa tion 8.22 in the Fluent Theor y Guide . This c ontrol app ears af ter y ou gener ate or r ead a PDF table in to ANSY S Fluen t. Chemistr y tab c ontains the par amet ers t o define pr oblems using the chemistr y mo del. See Setting U p the E quilibr ium Chemistr y Model (p.1691 ) for details . State Rela tion Chemic al E quilibr ium enables the equilibr ium chemistr y mo del. See Setting U p the E quilibr ium C hemistr y Model (p.1691 ) for details . Stead y Diffusion F lamelet enables the st eady diffusion flamelet mo del. See The D iffusion F lamelet M odels Theor y in the Theor y Guide for details . Unstead y Diffusion F lamelet enables the E uler ian unst eady diffusion flamelet mo del. Diesel U nstead y Flamelet enables the diesel unst eady laminar flamelet mo del. See Using the D iesel U nsteady Laminar Flamelet M odel (p.1698 ) for details . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3300Task P age R eference GuideFlamelet G ener ated M anif old enables the flamelet gener ated manif old (FGM) mo del. This is a vailable when the Partially P re- mix ed C ombustion mo del is selec ted. See Partially P remix ed C ombustion in the Theor y Guide for details . Energy Treatmen t Adiaba tic enables adiaba tic mo deling options f or the pr oblem. Non-A diaba tic enables non-adiaba tic mo deling options f or the pr oblem. See Non-A diaba tic Ex tensions of the Non-P remix ed M odel in the Theor y Guide for details . Coal C alcula tor opens the Coal C alcula tor D ialog Box (p.3312 ). Stream Options contains the par amet ers f or the equilibr ium chemistr y mo del or the st eady diffusion flamelet mo del. Secondar y Stream includes the sec ondar y inlet str eam in the mo del. Empir ical F uel S tream enables par amet ers t o define fuel str eam empir ically.This option is a vailable only with the full equilibr ium chemistr y mo del. Empir ical S econdar y Stream enables par amet ers t o define sec ondar y str eam empir ically.This option is a vailable only with the full equilibr ium chemistr y mo del. Model S ettings contains a list of par amet er settings . Operating P ressur e specifies the sy stem op erating pr essur e used t o calcula te the densit y using the ideal gas la w. See Specifying the Op erating P ressur e for the S ystem (p.1693 ) for details . Fuel S tream R ich F lammabilit y Limit specifies the r ich flammabilit y limit f or fuel str eam when the equilibr ium chemistr y option is used . You will not set these if y ou ha ve used the empir ical definition option f or fuel c omp osition. See Enabling the R ich F lammabilit y Limit (RFL) Option (p.1695 ) for details . Secondar y Stream F lammabilit y Limit specifies the r ich flammabilit y limit f or sec ondar y str eam when the equilibr ium chemistr y option is used .You will not set these if y ou ha ve used the empir ical definition option f or fuel c omp osition. See Enabling the R ich F lammabilit y Limit (RFL) Option (p.1695 ) for details . Empir ical F uel L ower C alor ific Value specifies the lo wer calor ific v alue of fuel str eam. Empir ical F uel S pecific H eat specifies the sp ecific hea t value of fuel str eam. 3301Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageEmpir ical F uel M olecular Weigh t specifies the molecular w eigh t of the fuel str eam. Empir ical S econdar y Lower C alor ific Value specifies the lo wer calor ific v alue of sec ondar y str eam. Empir ical S econdar y Specific H eat specifies the sp ecific hea t value of sec ondar y str eam. Empir ical S econdar y M olecular Weigh t specifies the molecular w eigh t of the sec ondar y str eam. Options contains options r elated t o the st eady flamelet mo del. Create Flamelet enables the Imp ort CHEMKIN M echanism... butt on tha t op ens the Imp ort CHEMKIN F ormat Mechanism D ialog Box (p.3755 ) wher e you c an imp ort the CHEMKIN mechanism and ther mody- namic da ta, to create a flamelet file .This option is a vailable f or the st eady flamelet mo del. See Setting U p the S teady and U nsteady Diffusion F lamelet M odels (p.1696 ) for details . Imp ort Flamelet enables the Imp ort Flamelet F ile... butt on tha t op ens The S elec t File D ialog Box (p.569) wher e you c an selec t the e xisting flamelet in ANSY S Fluen t.You c an also set the file t ype par amet ers t o imp ort the e xisting flamelet in ANSY S Fluen t. See Setting U p the S teady and U nsteady Diffusion Flamelet M odels (p.1696 ) for details .This option is a vailable f or the st eady flamelet mo del. Flamelet Type gives y ou the option of cr eating a Premix ed F lamelet or a Diffusion F lamelet .This is a vailable when the Flamelet G ener ated M anif old mo del is selec ted. Flamelet S olution M etho d allows you t o solv e the pr emix ed FGM either in the CHEMKIN P hysical S pac e or in the Progress Variable S pac e.This is a vailable when the Flamelet G ener ated M anif old state reaction is selec ted and Premix ed F lamelet is selec ted as the Flamelet Type. File Type contains the t oggle butt ons f or two flamelet file t ypes. Standar d enables the imp ort of an ASCII f ormat standar d flamelet file . CFX-RIF enables the imp ort of an ASCII f ormat CFX-RIF flamelet file . Flamelet P roperty File N ame opens The S elec t File D ialog Box (p.569) in which y ou c an sa ve the e xisting flamelet in ANSY S Fluen t to use when r unning an e xisting c ase. Thermodynamic D atabase F ile N ame specifies a pa th for the ther modynamic da tabase file t o be read. Boundar y tab c ontains the list of b oundar y sp ecies and r elated par amet ers.This is a vailable only f or equilibr ium chemistr y mo del. See Defining the S tream C omp ositions (p.1702 ) for details . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3302Task P age R eference GuideSpecies contains the list of the sp ecies used in the pr oblem. Fuel specifies the fuel sp ecies . Oxid specifies the o xidizing sp ecies . Second specifies the sec ondar y sp ecies . Boundar y Species allows you t o sp ecify the sp ecies y ou w ant to add or r emo ve from the mo del. You c an t ype the sp ecies chemic al formula in the field b elow it. Add adds the sp ecies in the mo del. Remo ve remo ves the sp ecies fr om the mo del. List A vailable S pecies prints a list of all sp ecies in the ther modynamic da tabase file ( thermo.db ) in the c onsole windo w. Temp erature specifies the t emp erature of diff erent str eams tha t you ha ve defined . Fuel is the t emp erature of the fuel inlet in the mo del. Oxid is the t emp erature of the o xidiz er inlet in the mo del. Second is the t emp erature of the sec ondar y str eam inlet in the mo del. Specify S pecies in allows you t o define the unit of sp ecies c oncentration. Mass F raction allows you t o sp ecify the sp ecies in t erms of mass fr action. Mole F raction allows you t o sp ecify the sp ecies in t erms of mole fr action. Control tab c ontains the par amet ers f or e xclusion and inclusion of equilibr ium sp ecies .This is a vailable only f or equilibr ium chemistr y mo del. See Forcing the Ex clusion and Inclusion of E quilibr ium S pecies (p.1714 ) for details . Species E xcluded fr om E quilibr ium lists the sp ecies e xcluded fr om equilibr ium c alcula tion. 3303Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageSpecies lists the slo w-forming sp ecies tha t are zeroed in the initial flamelet pr ofile . Add allows you t o add equilibr ium sp ecies . Remo ve allows you t o remo ve equilibr ium sp ecies . List A vailable S pecies prints a list of all sp ecies in the ther modynamic da tabase file in the c onsole windo w. Flamelet C ontrols allows you t o adjust the c ontrols f or the flamelet solution. Note tha t the Create Flamelet option in the Chemistr y tab must b e selec ted f or the Stead y Diffusion F lamelet or Flamelet G ener ated Manif old mo dels f or these c ontrols t o be available . Initial F our ier N umb er sets the first time st ep f or the solution. Four ier N umb er M ultiplier increases the time st ep a t subsequen t times . Every time st ep af ter the first is multiplied b y this value . Rela tive Error Toler anc e and A bsolut e Error Toler anc e specifies the lo cal er ror controls dur ing numer ical in tegration. Flamelet C onvergenc e Toler anc e specifies the maximum absolut e change in sp ecies fr action or t emp erature at an y discr ete mix ture- fraction. Maximum In tegration Time specifies the maximum t otal elapsed time f or flamelet c alcula tion. ANSY S Fluen t will st op the flamelet c alcula tion af ter the t otal elapsed time has e xceeded this v alue . Flamelet tab allo ws you t o adjust the c ontrols f or the flamelet solution. See Defining the F lamelet C ontrols (p.1715 ) for details . Flamelet P aramet ers consist of the c ontrols f or the flamelet solution. Note The par amet ers ma y vary sligh tly if y ou selec ted the Flamelet G ener ated M anif old model (see Flamelet G ener ated M anifold (p.1762 ) for those sp ecific par amet ers). Numb er of G rid P oints in F lamelet specifies the numb er of mix ture fraction gr id p oints distr ibut ed b etween the o xidiz er ( ) and the fuel ( ). Maximum N umb er of F lamelets specifies the maximum numb er of laminar flamelet pr ofiles t o be calcula ted. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3304Task P age R eference GuideInitial Sc alar D issipa tion is the sc alar dissipa tion of the first flamelet in the libr ary. Scalar D issipa tion M ultiplier specifies the r atio of the sc alar dissipa tion st ep in which succ essiv e flamelets ar e gener ated when the sc alar dissipa tion is less than 1 s-1.This c orresponds t o for < 1 in Equa tion 8.53 in the Theor y Guide .This option is a vailable with the S teady Diffusion F lamelet mo del and D iffusion FGM only . Scalar D issipa tion S tep specifies the in terval between sc alar dissipa tion v alues (in s-1) for which multiple flamelets will be calcula ted.This c orresponds t o for ≥ 1 in Equa tion 8.53 in the Theor y Guide .This option is available with the S teady Diffusion F lamelet mo del and D iffusion FGM only . User D efined F lamelet P aramet ers enables y ou t o ho ok a user-defined func tion f or sc alar dissipa tion and mean mix ture fraction (or progress v ariable) gr id discr etiza tion Unstead y Flamelet P aramet ers consist of the c ontrols f or the unst eady flamelet solution. Numb er of G rid P oints in F lamelet specifies the numb er of mix ture fraction gr id p oints distr ibut ed b etween the o xidiz er ( ) and the fuel ( ). Mixture Fraction L ower Limit f or Initial P robabilit y is the limit a t which the unst eady flamelet mo del t emp orally c onvects and diffuses a mar ker probabilit y equa tion thr ough a st eady-sta te ANSY S Fluen t flo w-field . Maximum Sc alar D issipa tion is wher e flamelets e xtinguish a t lar ge sc alar dissipa tion (mixing) r ates. Cour ant Numb er is the numb er at which ANSY S Fluen t aut oma tically selec ts the time st ep f or the pr obabilit y equa tion based on this c onvective Courant numb er. Numb er of F lamelets specifies the numb er of unst eady laminar flamelets tha t ANSY S Fluen t will aut oma tically gener ate during the simula tion. Include E quilibr ium F lamelet determines whether the equilibr ium assumption is used t o comput e the pr ogress v ariable ( Equa- tion 10.3 in the Fluent Theor y Guide ). If this option is selec ted, ANSY S Fluen t will c omput e the pr ogress variable using equilibr ium. Other wise , the pr ogress v ariable will b e comput ed using the solution of flamelet gener ated with initial sc alar dissipa tion as a denomina tor in Equa tion 10.3 in the Fluent Theor y Guide This option is a vailable only with the diffusion FGM mo del. Automa ted G rid Refinemen t emplo ys an adaptiv e algor ithm, which inser ts gr id p oints so tha t the change of v alues , as w ell as the change of slop es, between succ essiv e gr id p oints is less than user-sp ecified t oler ances. Onc e this option enabled , you c an sp ecify the f ollowing par amet ers: •Initial N umb er of G rid P oints in F lamelet : calcula tes a st eady solution on a c oarse gr id. 3305Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P age•Maximum N umb er of G rid P oints in F lamelet •Maximum C hange in Value R atio: is in Equa tion 8.28 in the Theor y Guide . •Maximum C hange in S lope Ratio: is in Equa tion 8.29 in the Theor y Guide . •Refine flamelet based on : allo ws you t o selec t either the Stoichiometr ic mix ture fraction or Specified mix ture fraction . For Specified mix ture fraction , you must also sp ecify a mix ture fraction level at which the flamelet is solv ed dur ing the gr id refinemen t.This option is a vailable f or the premix ed FGM mo del only . Set F lamelet P aramet ers opens Unsteady Flamelet P aramet ers D ialog Box (p.3320 ). Calcula te Flamelets begins the laminar flamelet c alcula tion. Displa y Flamelets ... opens the Flamelet 3D Sur faces D ialog Box (p.3317 ) from which y ou c an displa y 2D plots and 3D sur faces showing the v ariation of sp ecies fr action or t emp erature with the mean mix ture fraction or sc alar dissipa tion. Initializ e Unstead y Flamelet P robabilit y initializ es the unst eady flamelet and its pr obabilit y mar ker equa tion. Displa y Unstead y Flamelet ... opens the Flamelet 2D C urves D ialog Box (p.3319 ) from which y ou c an displa y 2D plots of the diff erent variables . Table tab c ontains par amet ers t o create the lo ok-up table . See Calcula ting the L ook-U p Tables (p.1723 ) for details of the it ems list ed b elow. Note If you selec ted the Flamelet G ener ated M anif old mo del, the par amet ers will b e diff erent. See Calcula ting the L ook-U p Tables (p.1766 ) for those sp ecific par amet ers. Table P aramet ers consists of the c ontrols f or the lo okup table . A diff erent set of par amet ers f or y ou t o en ter will b e displa yed if Automa ted G rid Refinemen t is enabled or disabled . Initial N umb er of G rid P oints specifies the numb er of gr id p oints for the r esolution of the mean mix ture fraction, mix ture fraction varianc e, and mean en thalp y (for non-adiaba tic sy stems). Maximum N umb er of G rid P oints specifies the maximum numb er of gr id p oints used f or tabula tion. The gr id refinemen t procedur e will st op inser ting the p oints when either the change in v alue and slop e between succ essiv e points is within t oler ance or the maximum numb er of gr id p oints ar e gener ated. Maximum C hange in Value R atio specifies the maximum allo wable change in v alue of table v ariables b etween succ essiv e gr id points as sp ecified b y Equa tion 8.28 in the Theor y Guide . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3306Task P age R eference GuideMaximum C hange in S lope Ratio specifies the maximum change in the slop e of table v ariables b etween succ essiv e gr id p oints as specified b y Equa tion 8.29 in the Theor y Guide . Maximum N umb er of S pecies is the maximum numb er of sp ecies st ored in the lo okup tables . Minimum Temp erature specifies the minimum t emp erature in the lo okup tables . Numb er of M ean M ixture Fraction P oints is the numb er of discr ete values of at which the lo ok-up tables will b e comput ed. Numb er of S econdar y M ixture Fraction P oints is the numb er of discr ete values of at which the lo ok-up tables will b e comput ed.This option is available only when a sec ondar y str eam has b een defined . Numb er of M ixture Fraction Varianc e Points is the numb er of discr ete values of at which the lo ok-up tables will b e comput ed.This option is available only when no sec ondar y str eam has b een defined . Maximum N umb er of S pecies is the maximum numb er of sp ecies tha t will b e included in the lo ok-up tables . Numb er of M ean E nthalp y Points is the numb er of discr ete values of en thalp y at which the thr ee-dimensional lo ok-up tables will be comput ed.This input is r equir ed only if y ou ar e mo deling a non-adiaba tic sy stem. Minimum Temp erature is used t o det ermine the lo west t emp erature for which the lo ok-up tables ar e gener ated (see Figur e 8.10: Visual R epresen tation of a L ook-U p Table f or the Sc alar as a F unction of M ean M ixture Fraction and M ixture Fraction Varianc e and N ormaliz ed H eat Loss/G ain in N on-A diaba tic S ingle- Mixture-Fraction S ystems in the Theor y Guide ).This option is a vailable only if y ou ar e mo deling a non-adiaba tic sy stem. Automa ted G rid Refinemen t is an adaptiv e algor ithm tha t inser ts gr id p oints in all table dimensions so tha t changes in the v alues of tabula ted v ariables (such as mean t emp erature, densit y and sp ecies mass fr actions) b etween suc- cessiv e gr id p oints, as w ell as changes in their slop es, are less than a user sp ecified t oler ance. Include E quilibr ium F lamelet specifies tha t an equilibr ium flamelet (tha t is, ) will b e gener ated in ANSY S Fluen t and app ended to the flamelet libr ary before the PDF table is c alcula ted.This option is a vailable only with the st eady diffusion flamelet mo del. FGM Sc alar Transp ort opens the Selec t Transp orted Sc alars D ialog Box (p.3321 ). Calcula te PDF Table gener ates the lo ok-up table . 3307Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageDispla y PDF Table opens the PDF Table D ialog Box (p.3322 ) wher e you c an displa y 2D plots and 3D sur faces sho wing the variation of sp ecies mole fr action, densit y, or t emp erature with the mean mix ture fraction, mix ture fraction v arianc e, or en thalp y. Properties tab c ontains par amet ers needed t o mo dify the piec ewise-linear p oints. See Modifying the U nbur nt Mixture Property Polynomials (p.1773 ) for the details . Partially P remix ed M ixture Properties contains the list of pr operties tha t you c an mo dify.Edit... opens the Quadr atic M ixture Fraction dialo g box wher e you c an mo dify the v alues of the p olynomial c oefficien ts. For each p olynomial func tion of under Partially P remix ed M ixture Properties you c an click Edit... and sp ecify v alues f or Coefficien t 1,Coefficien t 2,Coefficien t 3, and Coefficien t 4 in the appr opriate Quadr atic of M ixture Fraction dialo g box. Non-A diaba tic L aminar F lame S peed when enabled includes the non-adiaba tic eff ects on the laminar flame sp eed b y tabula ting the lam- inar sp eeds in the PDF table . See Laminar F lame S peed in the Theor y Guide . Rec alcula te Properties will c alcula te the par tially pr emix ed pr operties. Premix tab c ontains options and par amet ers f or the Turbulen t Flame S peed M odel, the Varianc e Settings , and the Turbulenc e-Chemistr y In teraction . Note Note tha t the Turbulen t Flame S peed M odel controls ar e available f or b oth pr emix ed and par tially pr emix ed c ombustion mo dels . However, for the par tially pr emix ed c ombus- tion mo del, the y are or ganiz ed in the Premix tab . Turbulen t Flame S peed M odel allows you t o selec t the Flame S peed M odel and sp ecify its par amet ers.This sec tion will app ear only if Premix ed C ombustion or Partially P remix ed C ombustion is the selec ted Model and if the C Equa tion or G Equa tion premix ed mo del is chosen. Flame S peed M odel is a dr op-do wn list in which y ou c an selec t the turbulen t flame sp eed mo del. You c an cho ose between zimon t (see Zimon t Turbulen t Flame S peed C losur e Model in the Fluent Theor y Guide ) and peters (see Peters F lame S peed M odel in the Fluent Theor y Guide ). Turbulen t Length Sc ale C onstan t (zimon t mo del) sp ecifies the v alue of in Equa tion 9.10 in the Theor y Guide . Turbulen t Flame S peed C onstan t (zimon t mo del) sp ecifies the v alue of in Equa tion 9.8 in the Theor y Guide . Stretch F actor C oefficien t (zimon t mo del) sp ecifies the v alue of in Equa tion 9.16 in the Theor y Guide . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3308Task P age R eference GuideWall D amping C oefficien t specifies the v alue of in Equa tion 9.19 (premix ed c ombustion mo del) or in Equa tion 10.10 in the Fluent Theor y Guide (par tially pr emix ed c ombustion mo del). Turbulen t Schmidt N umb er specifies the v alue of in Equa tion 9.1 in the Theor y Guide . Turbulen t Length Sc ale C onstan t (R ANS) (zimon t mo del) is the mo deling c onstan t in the R ANS r egion ( in Equa tion 9.10 in the Theor y Guide ).This option is a vailable f or the P artially P remix ed C ombustion mo del with the SBES mo del only . Turbulen t Flame S peed C onstan t (R ANS) (zimon t mo del) is the mo deling c onstan t in the R ANS r egion ( in Equa tion 9.8 in the Theor y Guide ).This option is a vailable f or the P artially P remix ed C ombustion mo del with the SBES mo del only . Ewald C orrector (peters mo del) is enabled b y default and descr ibed in Peters F lame S peed M odel. Blin t Modifier (peters mo del) enables/disables B lint's c orrelation f or laminar flame thick ness (used in Equa- tion 9.21 thru Equa tion 9.23 in the Fluent Theor y Guide ). See Peters F lame S peed M odel in the Fluent Theor y Guide for mor e inf ormation. G Equa tion S ettings allows you t o selec t either the transp ort equa tion or algebr aic option f or the c alcula tion of the flame distanc e varianc e. Consult Peters F lame S peed M odel in the Theor y guide f or the v arianc e transp ort and algebr aic equa tion e xpressions ( Equa tion 9.5 and Equa tion 9.6 ). Flame C urvature Sour ce includes the cur vature sour ce term in the G-E qua tion, which is the last t erm in Equa tion 9.3 . Turbulenc e-Chemistr y In teraction (par tially-pr emix ed c ombustion FGM mo del only) allo ws you t o cho ose b etween Finit e-Rate and Turbulen t Flame S peed . For mor e inf ormation ab out these mo dels , see FGM Turbulen t Closur e in the Theor y Guide . Varianc e Settings is available f or the G Equa tion premix ed or par tially pr emix ed mo del and C Equa tion par tially pr emix ed FGM mo del. Varianc e M etho d is a dr op-do wn list tha t allo ws you t o cho ose b etween transp ort equa tion and algebr aic. If the SBES mo del is enabled , you c an also cho ose hybr id. Consult FGM Turbulen t Closur e in the Fluent Theor y Guide for the C Equa tion mo del ( Equa tion 10.12 and Equa tion 9.23 ) and G-Equa tion Model Theor y in the Fluent Theor y Guide for the G-E qua tion mo del ( Equa tion 9.5 and Equa tion 9.6 ). It is r ecommended tha t you use the transp ort equa tion option f or R ANS, the algebr aic option for LES, and the hybr id for SBES. Premix ed C ombustion M odel Options contains options f or the pr emix ed c ombustion mo del. (This sec tion will app ear only if Premix ed C om- bustion is the selec ted Model.) 3309Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageAdiaba tic enables the adiaba tic pr emix ed c ombustion mo del, which c alcula tes temp erature using Equa tion 9.66 in the Theor y Guide . Non-A diaba tic enables the non-adiaba tic pr emix ed c ombustion mo del, which c alcula tes temp erature using Equa- tion 9.67 in the Theor y Guide . Premix ed M odel contains options f or cho osing a pr emix ed mo del. C Equa tion allows you t o cho ose the C equa tion as descr ibed in C-Equa tion M odel Theor y. Extended C oher ent Flamelet M odel allows you t o cho ose the Ex tended C oher ent Flamelet mo del as descr ibed in Extended C oher ent Flamelet M odel Theor y. G Equa tion allows you t o cho ose the G equa tion as descr ibed in G-Equa tion M odel Theor y. Extended C oher ent Flamelet M odel C onstan ts contains mo del c onstan ts for the Ex tended C oher ent Flame M odel. (This sec tion will app ear only if Pre- mix ed C ombustion or Partially P remix ed C ombustion is the selec ted Model and if the Extended C o- herent Flame M odel flame sp eed mo del is chosen.) S ee Modifying the C onstan ts for the ECFM F lame Speed C losur e (p.1755 ) for details . Note tha t for the par tially pr emix ed c ombustion mo del, Extended C o- herent Flamelet M odel C onstan ts app ear in the Premix tab . ITNFS Treatmen t contains a dr op-do wn list of the a vailable ITNFS tr eatmen ts:constan t-delta ,mene veau ,blin t, poinsot , and constan t. ITNFS F lame Thick ness sets the flame thick ness ( Equa tion 9.30 in the Theor y Guide ). Turbulen t Schmidt N umb er set the turbulen t Schmidt numb er ( ). Wall F lux C oefficien t set the w all flux c oefficien t. PDF Transp ort Options contains options f or the C omp osition PDF Transp ort combustion mo del. (This sec tion will app ear only if Comp osition PDF Transp ort is the selec ted Model.) Lagrangian solv es the c omp osition PDF tr ansp ort equa tion b y stochastic ally tr acking Lagr angian par ticles thr ough the domain. Euler ian assumes a shap e for the PDF , allo wing E uler ian tr ansp ort equa tions t o be der ived. Mixing tab c ontains the mixing mo dels . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3310Task P age R eference GuideMixing M odel contains options t o sp ecify the metho d for mo deling molecular diffusion. (This sec tion will app ear only if Comp osition PDF Transp ort is the selec ted Model.) See Particle M ixing in the Theor y Guide for details . Modified C url enables the mo dified cur l mo del f or molecular diffusion. IEM enables the IEM mo del f or molecular diffusion. EMST enables the EMST mixing mo del f or molecular diffusion. Mixing C onstan t specifies the v alue of the mixing c onstan t in Equa tion 11.6 and Equa tion 11.8 in the Theor y Guide . Boundar y tab allo ws you t o define the fuel and o xidiz er comp ositions .This is only a vailable if y ou selec t Euler ian as the PDF Transp ort Option . Species consists of the fuel sp ecies and the o xidiz er. Fuel is the mole or mass fr action of the fuel str eam. The sum of mass or mole fr actions of all sp ecies in the fuel str eam should b e 1. Oxidiz er is the mole or mass fr action of the o xidiz er str eam. The sum of mass or mole fr actions of all sp ecies in the fuel o xidiz er str eam should b e 1. Specify S pecies in specifies the sp ecies as a Mass F raction or Mole F raction . Control tab c ontains Lagr angian PDF tr ansp ort par amet ers. PDF Transp ort Paramet ers allows you t o set the Particles P er C ell. Particles P er C ell sets the numb er of PDF par ticles p er cell. Higher v alues of this par amet er will r educ e sta tistic al error, but incr ease c omputa tional time . Local Time S tepping toggles the c alcula tion of lo cal time st eps. If this option is disabled , then y ou will need t o sp ecify the Time S tep directly (see Equa tion 11.4 in the Theor y Guide ).This option is a vailable f or st eady- state simula tions . Convection # specifies the par ticle c onvection numb er (see in Equa tion 11.4 in the Theor y Guide ). 3311Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageDiffusion # specifies the par ticle diffusion numb er (see in Equa tion 11.4 in the Theor y Guide ). Mixing # specifies the par ticle mixing numb er (see in Equa tion 11.4 in the Theor y Guide ). 47.4.19. Coal C alcula tor D ialo g Box The Coal C alcula tor dialo g box (op ened b y click ing Coal C alcula tor... in the Species M odel dialo g box) aut oma tes the c alcula tions descr ibed in Additional C oal M odeling Inputs in ANSY S Fluen t (p.1710 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3312Task P age R eference GuideControls Coal S treams allows you t o set up t o thr ee c oal str eams (S pecies Transp ort mo del only). Numb er of C oal S treams specifies the t otal numb er of c oal str eams . 3313Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageID sets the ID of the c oal str eam f or which y ou w ant to sp ecify Coal P roperties . Coal P roperties contains inputs f or the cur rent coal str eam. Proxima te Analy sis is the mass fr action of Volatile,Fixed C arb on,Ash, and Moistur e in the c oal. Volatile is the fr action of the v olatile c omp onen t. Fixed C arb on is calcula ted as one minus the sum of the ac tual Volatile,Ash, and Moistur e fractions . Ash is the fr action of ash. Moistur e is the moistur e fraction in the c oal. Ultima te Analy sis (DAF) is the mass fr action of a tomic C, H, O, N and optionally S, in the D ry-Ash-F ree (DAF) c oal. Mechanism allows you t o set the mechanisms . Secondar y Stream when enabled , allo ws you t o set the t wo mix ture fraction mo del with the pr imar y str eam r epres- enting char as , and an empir ical sec ondar y str eam r epresen ting the v olatiles .This is a vailable when using the non-pr emix ed c ombustion mo del. One-st ep Reac tion is defined in Equa tion 15.6 (p.1648 ). Two-st ep Reac tion involves o xida tion of v olatiles t o CO in the first r eaction and o xida tion of C O to CO2 in the sec ond reaction, as descr ibed in Equa tion 15.7 (p.1648 ). Include SO2 when enabled , allo ws you t o sp ecify the a tomic mass fr action of sulphur ,S, which app ears under Ultima te Analy sis. Options Wet C ombustion when enabled will enable the DPM Wet C ombustion option b y default in all injec tions cr eated after the OK butt on is click ed in the Coal C alcula tor dialo g box. Settings is wher e you will sp ecify the v alues used in the c alcula tion. Coal P article M aterial N ame is the name of the DPM c ombusting par ticle ma terial.The default name is coal-par ticle . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3314Task P age R eference GuideCoal A s-Rec eived HCV is the higher c alor ic value of the c oal. Volatile M olecular Weigh t is the molecular w eigh t of pur e volatiles . CO/C O2 S plit in Reac tion 1 P roduc ts can b e used t o sp ecify the molar fr action of C O to CO2 in the first r eaction of Equa tion 15.7 (p.1648 ). The default v alue of 1 implies tha t all c arbon is r eacted t o CO, with no C O2 produced. High Temp erature Volatile Yield is wher e the enhanc ed de volatization a t higher t emp eratures c an c ause the v olatile yield t o exceed the pr oxima te analy sis fr action. Fraction of N in C har (DAF) is used in c alcula ting the split of a tomic nitr ogen f or the F uel NO x mo del. Coal D ry Densit y is used t o calcula te the Volume F raction of liquid-w ater for the Wet C ombustion option in the Injec tions dialo g box. Gas P hase Reac tion lists the r eaction based on y our en tries f or the pr oxima te and ultima te analy ses. 47.4.20. Integration P aramet ers D ialo g Box The Integration P aramet ers dialo g box (op ened b y click ing Integration P aramet ers... in the Species Model dialo g box) allo ws you t o set the par amet ers f or the in tegration of the chemic al sour ce term in Equa tion 11.10 in the Theor y Guide . See Using ISA T (p.1794 ) for details . Integration M etho d contains options t o cho ose the metho d for in tegration. ISAT enables the ISA T option and e xpands the dialo g box to include inputs f or ISAT Paramet ers. 3315Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageDirect Integration enables the dir ect integration metho d to integrate the chemic al sour ce term in the c alcula tion. ODE P aramet ers contains options t o sp ecify the er ror toler ances. Absolut e Error Toler anc e specifies the absolut e error toler ance. Rela tive Error Toler anc e specifies the r elative error toler ance. ISAT Paramet ers contains inputs r equir ed f or ISA T integration metho d. ISAT Error Toler anc e controls the numer ical er ror in ISA T liner in terpolation. Decrease this v alue t o get accur ate minor species and p ollutan t predic tions . Max. Storage is the maximum R AM used b y the ISA T table , and has a default v alue is 100 MB . Verb osit y specifies the le vel of detail a t which y ou c an monit or the ISA T performanc e. Clear ISA T Table purges the ISA T table . Options contains options t o cho ose the metho d for chemistr y acc eleration. Dynamic M echanism Reduc tion accelerates chemistr y by reducing the chemic al kinetics mechanism on-the-fly t o include only imp ortant species and r eactions , with a c orresponding decr ease in accur acy.This metho d is a vailable f or Stiff Chemistr y Solver only . Chemistr y Agglomer ation when enabled , provides additional r un-time impr ovemen t, with a c orresponding decr ease in accur acy. This metho d is a vailable f or Stiff C hemistr y Solver and Relax t o Chemic al E quilibr ium only . Dimension Reduc tion is a chemistr y acc eleration metho d in addition t o ISA T storage-r etrieval and C ell A gglomer ation, providing fast er chemistr y calcula tions with a c orresponding loss of accur acy.This metho d is a vailable for Stiff C hemistr y Solver only . Dynamic C ell C lust ering enables a c omputa tionally efficien t dynamic c ell clust ering metho d (DC C) tha t groups c omputa tional cells of high similar ity into clust ers using t wo DC C par amet ers: •Max.Temp erature Dispersion (default =10 K) •Max. Equiv . Ratio D ispersion (default =0.05) •Max. Clust erization (default = 10) •Min. Clust erization (default = 0) •Reac tants Threshold (mass fr action) (default = 1e-09) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3316Task P age R eference GuideThis option is enabled b y default and r ecommended . It is a vailable only with the CHEMKIN- CFD S olver. Dynamic A daptiv e Chemistr y accelerates chemistr y by reducing the chemic al kinetics mechanism on-the-fly t o locally v alid smaller mechanisms , with a c orresponding decr ease in accur acy.The le vel of accur acy is c ontrolled b y DAC Error Toler anc e.You c an selec t the initial tar get sp ecies t o be tracked b y the DA C algor ithm in the Selec t DA C Target S pecies dialo g box tha t op ens when y ou click Selec t Target S pecies . See Using Dynamic A daptiv e Chemistr y with ANSY S Fluen t CHEMKIN-CFD S olver (p.1804 ) for mor e details . This option is a vailable only with the CHEMKIN-CFD S olver. Agglomer ation P aramet ers contains settings f or the agglomer ation chemistr y metho d. Error Toler anc e determines the siz e of the clust ers f or sp ecies . By default , the v alue is 0.05. Temp erature Bin specifies the maximum bin siz e for temp erature.The default v alue is 100 K. Dimension Reduc tion P aramet ers contains settings t o acc elerate the chemistr y. Numb er of Repr esen ted S pecies must b e gr eater than 10 and less than the numb er of sp ecies in the full mechanism. The Numb er of Repr esen ted S pecies must also b e less than 50 minus the numb er of unr epresen ted elemen ts (the numb er of chemic al elemen ts in the unr epresen ted sp ecies). Full M echanism M aterial N ame is typic ally the name of the CHEMKIN mechanism tha t you imp orted. Fuel/O xidiz er S pecies is wher e the b oundar y and initial fuel and o xidiz er, as w ell as pr oduc t species , are set as r epresen ted species . Create Reduc ed D imension M ixture creates a new mix ture ma terial c alled reduced-dimension-mixture , which c ontains the r epres- ented sp ecies as w ell as pr oxy ’species ’ for the unr epresen ted elemen ts. 47.4.21. Flamelet 3D S urfaces D ialo g Box The Flamelet 3D S urfaces dialo g box allo ws you t o displa y 2D plots and 3D sur faces sho wing the variation of sp ecies fr action or t emp erature with the mean mix ture fraction or sc alar dissipa tion. See Postpr ocessing the F lamelet D ata (p.1720 ) for details . 3317Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageFlamelet Type indic ates the t ype of flamelets whose sur faces will b e displa yed. Plot Variable enables y ou t o cho ose t emp erature or sp ecies fr action as the v ariable t o be plott ed. Plot Type consists of options f or plot t ype. 3D S urface enables plotting on 3D sur faces. 2D cur ve on 3D sur face enables plotting of a 2D cur ve on a 3D sur face. Options consists of the f ollowing par amet ers: Draw N umb ers B ox enables the displa y of a wir eframe b ox with the numer ical limits in each c oordina te dir ection. Write To File enables sa ving the plot da ta to a file . Curve Paramet ers consists of c ontrols r elated t o plot displa y. X-A xis F unc tion consists of the func tion against which the plot v ariable will b e displa yed. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3318Task P age R eference GuideScalar D issipa tion enables displa y of plot v ariable against the sc alar dissipa tion func tion. Mixture Fraction enables displa y of plot v ariable against the mix ture fraction. Constan t Value of Sc alar D issipa tion consists of the c ontrols t o sp ecify the t ype of discr etiza tion (tha t is, how the flamelet da ta will b e sliced) f or the v ariable tha t is b eing held c onstan t. Slice by consists of the c ontrols t o sp ecify discr etiza tion. Inde x enables y ou t o sp ecify discr etiza tion inde x of the v ariable tha t is b eing held c onstan t. Value enables y ou t o sp ecify the numer ical value of the v ariable tha t is b eing held c onstan t. Inde x consists of the c ontrols tha t are displa yed when y ou enable Inde x under Slice by. Inde x # displa ys the inde x numb er. Min displa ys the minimum of the r ange of in teger v alues tha t you ar e allo wed t o cho ose fr om. Max displa ys the maximum of the r ange of in teger v alues tha t you ar e allo wed t o cho ose fr om. Value consists of the c ontrols tha t are displa yed when y ou enable Value under Slice by. Value enables y ou t o en ter the numer ical value of the v ariable tha t is b eing held c onstan t. Min displa ys the minimum of the r ange of in teger v alues tha t you ar e allo wed t o cho ose fr om. Max displa ys the minimum of the r ange of in teger v alues tha t you ar e allo wed t o cho ose fr om. 47.4.22. Flamelet 2D C urves D ialo g Box The Flamelet 2D C urves dialo g box allo ws you t o displa y or wr ite 2D cur ves of the unst eady flamelet. See Postpr ocessing the F lamelet D ata (p.1720 ) for details . 3319Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageOptions gives y ou the option t o plot or Write to File 2D cur ves. Plot Variable consists of a dr op-do wn list of v ariables tha t you c an plot or wr ite. Plot is available b y default. When the Write to File option is enabled the Plot butt on changes t o a Write.... 47.4.23. Unstead y Flamelet P aramet ers D ialo g Box The Unstead y Flamelet P aramet ers dialo g box (op ened b y click ing Set F lamelet P aramet ers in the Flamelet tab of the Species M odel dialo g box) allo ws you t o sp ecify the initia tion time of the unst eady flamelets . See Using the D iesel U nsteady Laminar F lamelet M odel (p.1698 ) for details . Start CA (deg) is the time a t which each unst eady laminar flamelet will b e gener ated dur ing y our simula tion. The time is sp ecified in t erms of sec onds or degr ees of cr ank angle if the d ynamic mesh is enabled . Bur nt Initial F lamelet if enabled , sets the initial flamelet c ondition t o a chemic al equilibr ium bur nt sta te. Other wise , the initial flamelet c ondition is set t o unbur nt sta te (default). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3320Task P age R eference Guide47.4.24. Flamelet F luid Z ones D ialo g Box The Flamelet F luid Z ones dialo g box allo ws you t o selec t the fluid z ones f or c omputing z one-a veraged pressur e and sc alar dissipa tion. The dialo g box is op ened b y click ing Set F lamelet F luid Z ones in the Flamelet tab of the Species M odel dialo g box. See Using the D iesel U nsteady Laminar F lamelet Model (p.1698 ) for details . Fluid Z ones is a selec table list of the fluid z ones o ver which the a verage pr essur e and sc alar dissipa tion ar e comput ed. 47.4.25. Selec t Transp orted Sc alars D ialo g Box The Selec t Transp orted Sc alars dialo g box (op ened b y click ing FGM Sc alar Transp ort in the Table tab of the Species M odel dialo g box) allo ws you t o selec t the sp ecies f or which tr ansp ort equa tions will b e solv ed. See Calcula ting the L ook-U p Tables (p.1766 ) for mor e inf ormation ab out the it ems b elow. Controls 3321Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageAvailable S pecies is a list of sp ecies a vailable in the FGM flamelet table (either gener ated or imp orted). To add a sp ecies t o the Transp orted Sc alars list, selec t it in the Available S pecies multiple-selec tion list and click Add. Transp orted Sc alars is a list of selec ted sp ecies f or which the tr ansp ort equa tions will b e solv ed, as descr ibed in Scalar Transp ort with FGM C losur e in the Fluent Theor y Guide .To remo ve a sp ecies fr om the Transp orted Sc alars list back to the Available S pecies multiple-selec tion list , selec t it and click Remo ve. 47.4.26. PDF Table D ialo g Box You c an displa y 2D plots and 3D sur faces sho wing the v ariation of sp ecies mole fr action, densit y, or temp erature with the mean mix ture fraction, mix ture fraction v arianc e, or en thalp y. For the F lamelet Gener ated M anifold (FGM) mo del, additional v ariables ar e available f or gener ating plots f or PDF lo okup tables . See Postpr ocessing the L ook-U p Table D ata (p.1728 ) for details ab out the it ems b elow. The PDF Table dialo g box can b e acc essed in one of t wo ways: •by click ing the Displa y PDF Table ... butt on in the Table tab of the Species M odel dialo g box (as sho wn in Figur e 16.23: The S pecies M odel D ialog Box (Table) Tab Ex cluding A utoma ted G rid R efinemen t (p.1725 )) •by using the f ollowing pa th: Postpr ocessing → Model S pecific → PDF Table ... Controls Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3322Task P age R eference GuidePDF D ata Type descr ibes the sy stem tha t you ar e displa ying . Plot Variable is a dr op-do wn list fr om which y ou c an selec t temp erature, densit y, or sp ecies mass fr action as the v ariable to be plott ed. For the FMG mo del, you c an also selec t mean r ate of r eaction pr ogress. Enthalp y Slice, Adiaba tic = slice number (FGM mo del only) sp ecifies the v alue of the en thalp y slic e level. By default , the en thalp y level is fix ed a t the adiaba tic le vel displa yed in the lab el as Adiaba tic = slice number . Enthalp y slic e numb ers b elow the adiaba tic slic e numb er ar e asso ciated with hea t loss , while en thalp y slic e numb ers ab ove the adiaba tic slice numb er ar e asso ciated with en thalp y gain. Scalar D issipa tion (multiple flamelets only) sp ecifies the v alue of the Scalar D issipa tion . Plot Type gives y ou the choic e of plotting a 3D sur face or a slic e of a 3D sur face. 3D S urface displa ys a 3D plot of the v ariation of sp ecies mole fr action, densit y, or t emp erature with the mean mixture fraction, mix ture fraction v arianc e, or en thalp y. 2D C urve on 3D S urface consists of a 2D cur ve tha t is a slic e of a 3D sur face. Options contains options sp ecific t o the displa y of 3D sur faces or 2D cur ves on 3D sur faces. Draw N umb ers B ox enabling this option displa ys a wir eframe b ox with the numer ical limits in each c oordina te dir ection. This option is a vailable only when 3D S urface is selec ted. Write To File specifies whether y ou w ant to wr ite the plot da ta to a file .This option is a vailable only when 2D C urve on 3D S urface is selec ted.The Plot butt on changes t o a Write butt on when this option is enabled . Volume P aramet ers (FGM mo del only) c ontains settings f or selec ting and fixing a discr ete indep enden t variable . Constan t Value of contains the discr ete indep enden t variables tha t can b e held c onstan t in the lo okup table .The choic es are Mean Reac tion P rogress,Scaled Reac tion P rogress Varianc e,Mean M ixture Fraction , and Scaled Varianc e. Slice by allows you t o selec t whether the 3D ar ray of da ta p oints available in the lo ok-up table will b e slic ed by Inde x or Value . Inde x/Value contains inde x/values and their r anges . Inde x/Value allows you t o sp ecify the discr etiza tion inde x or numer ical value of the v ariable tha t is b eing held constan t. 3323Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageMin/M ax are the r ange of in teger v alues tha t you ar e allo wed t o cho ose fr om or displa y. Surface Paramet ers contains settings wher e discr ete indep enden t variables ar e held c onstan t and wher e cur ve par amet ers are defined . Constan t Value of contains the discr ete indep enden t variables tha t can b e held c onstan t in the lo okup table .The choic es are Scaled H eat Loss/G ain,Mean M ixture Fraction , and Scaled Varianc e. For a t wo-mix ture-fraction case, the Scaled H eat Loss/G ain is the only a vailable option. For the FGM mo del, this gr oup b ox contains the discr ete indep enden t variables tha t ha ve not b een fix ed in the Volume P aramet ers group b ox. Slice by allows you t o selec t whether the 3D ar ray of da ta p oints available in the lo ok-up table will b e slic ed by Inde x or Value . Inde x/Value contains inde x/values and their r anges . Inde x/Value allows you t o sp ecify the discr etiza tion inde x or numer ical value of the v ariable tha t is b eing held constan t. Min/M ax are the r ange of in teger v alues tha t you ar e allo wed t o cho ose fr om or displa y. Adiaba tic is the en thalp y slic e inde x corresponding t o the adiaba tic c ase f or which the en thalp y (Scaled Heat Loss/G ain) is held c onstan t. Curve Paramet ers allows you t o sp ecify the X-A xis F unc tion against which the plot v ariable will b e displa yed when 2D Curve on 3D S urface is selec ted. X-A xis F unc tion contains the r emaining discr ete indep enden t par amet ers tha t ha ve not b een fix ed y et. Constan t Value of Independent Parameter allows you t o sp ecify the t ype of discr etiza tion f or the v ariable tha t is b eing held c onstan t using the c ontrols in the Slice by and Inde x/Value group b oxes.These it ems ar e similar t o those de- scribed ab ove. Displa y displa ys the plot v ariable of the 3D sur face. Plot plots the plot v ariable f or the 2D cur ve on 3D sur face. Write opens The S elec t File D ialog Box (p.569) wher e you will sp ecify a name f or the file c ontaining plot da ta. This butt on app ears when Write To File is enabled f or the 2D C urve on 3D S urface plot t ype. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3324Task P age R eference Guide47.4.27. Spark Ignition D ialo g Box The Spar k Ignition dialo g box allo ws you t o define multiple spar ks (see Spark Model (p.1807 ) for details). Controls Numb er of S par ks is the quan tity of spar ks you w ould lik e to include in y our simula tion. You c an define up t o 16 spar ks. On if enabled , turns on those spar ks tha t will b e included in the simula tion. Name is the name of the spar k.You c an sp ecify a name , or use the default name . Define ... opens the Set Spark Ignition D ialog Box (p.3325 ). 47.4.28. Set S park Ignition D ialo g Box The Set S par k Ignition dialo g box allo ws you t o set the par amet ers r elated t o the spar k ignition model (see Spark Model (p.1807 ) for details). 3325Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageControls Name displa ys the name of the spar k being defined . Spar k Location contains the par amet ers needed t o define the lo cation and siz e of the spar k. X,Y, and Z-C enter specifies x, y, and z c oordina tes of the spar k center. Initial R adius specifies the initial spar k radius . Spar k Paramet ers contains the par amet ers needed t o define the spar k. Start Time is the time of spar k ignition initializa tion in sec onds .When the in-c ylinder mo del is tur ned on, this control is r eplac ed b y the Start Crank A ngle control. Start Crank A ngle is the time of spar k ignition initializa tion in cr ank angle degr ees.When the in-c ylinder mo del is tur ned off, this c ontrol is r eplac ed b y the Start Time option. Duration is the dur ation of the spar k ignition in sec onds . Energy contains the t otal ener gy input b y the spar k.The default ener gy value is 0. A p ositiv e value f or ener gy will c ause the t emp erature of the spar k kernel t o rise ab ove the c ombustion pr ocess t emp erature. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3326Task P age R eference GuideFlame S peed M odel allows you t o selec t the turbulen t flame sp eed mo del f or controlling the r ate at which the flame fr ont moves. Turbulen t Curvature includes the eff ect of flame cur vature as sp ecified in Turbulen t Curvature in the Fluent Theor y Guide . Turbulen t Length neglec ts the eff ects of flame cur vature on the flame sp eed as descr ibed in Turbulen t Length in the Fluent Theor y Guide . Herweg-M aly calcula tes the turbulen t flame sp eed using H erweg-M aly mo del. See Herweg-M aly in the Fluent Theor y Guide for details . Laminar specifies the turbulen t flame sp eed as the laminar flame sp eed.This option c an b e used t o apply user-defined func tion (UDF) f or the turbulen t flame sp eed definition. Flame S urface Densit y allows you t o sp ecify the flame sur face densit y as a c onstan t value when Constan t Value is selec ted under ECFM S par k M odel.The v alue of the flame sur face densit y must b e set within the spar k region. User S igma S our ce allows you t o apply a cust om sour ce term to the ECFM equa tion within the v olume of the spar k ignition kernel. For mor e detail ab out this user-defined func tion, refer to Hooking an ECFM S park Source UDF to ANSY S Fluen t in the Fluent C ustomization Manual .This selec tion is a vailable when User D efined Sigma S our ce is enabled under ECFM S par k M odel. ECFM S par k M odel contains mo del v ariants used t o define the v alue of the flame sur face densit y.These p ortions of the dialo g box only app ear when the Extended C oher ent Flamelet M odel (Setting U p the Ex tended C oher ent Flame M odel (p.1754 )) is selec ted in the Species M odel dialo g box. Turbulen t takes in to acc oun t flame wr inkling as descr ibed in Turbulen t Model in the Fluent Theor y Guide . Zimon t operates in the same w ay as the spar k mo del used with the Z imon t combustion mo del. See Zimon t Model in the Fluent Theor y Guide . Constan t Value allows you t o sp ecify the Flame S urface Densit y. User S igma S our ce allows you t o apply a cust om sour ce term to the ECFM equa tion within the v olume of the spar k ignition kernel. 47.4.29. Autoignition M odel D ialo g Box The Autoignition M odel dialo g box allo ws you t o set the par amet ers r elated t o the Knock M odel or the Ignition D elay M odel. See Modeling Engine Ignition (p.1807 ) for details . 3327Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageControls Model contains options t o disable or enable mo dels . Off disables the mo del. Knock M odel enables the k nock mo del. With the Premix ed C ombustion or Partially P remix ed C ombustion models selec ted, only the Knock M odel can b e tur ned on. Ignition D elay M odel enables the ignition dela y mo del. Options contains t wo correlation options tha t exist with each mo del. Douaud option is used f or k nock in spar k ignition engines .The mo deling par amet ers tha t are sp ecified f or this option ar e the Pre Exponen tial,Pressur e Exponen t,Activation Temp erature,Octane N umb er, and Octane E xponen t (Equa tion 13.9 in the Theor y Guide ). Gener aliz ed enables gener alized c orrelation descr ibed b y Equa tion 13.10 in the Theor y Guide . It requir es the same paramet ers as in the ignition dela y mo del. Hardenbur g enables Har denbur g correlation, which is used f or hea vy-dut y diesel engines .This option is enabled only f or the ignition dela y mo del. Model P aramet ers contains par amet ers r elated t o the selec ted mo del. See Using the A utoignition M odels (p.1811 ) for the details ab out the par amet ers in this dialo g box. Pre-Exponen tial see Equa tion 13.10 and Equa tion 13.9 in the Theor y Guide . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3328Task P age R eference GuideActivation Temp erature see Equa tion 13.9 in the Theor y Guide . Pressur e Exponen t see Equa tion 13.10 and Equa tion 13.9 in the Theor y Guide . Octane N umb er see Equa tion 13.10 and Equa tion 13.9 in the Theor y Guide . Octane N umb er E xponen t see Equa tion 13.10 and Equa tion 13.9 in the Theor y Guide . Activation E nergy see Equa tion 13.10 and Equa tion 13.12 in the Theor y Guide . Temp erature Exponen t see Equa tion 13.10 in the Theor y Guide . RPM E xponen t see Equa tion 13.10 in the Theor y Guide . Equiv alenc e Ratio E xponen t see Equa tion 13.10 in the Theor y Guide . Options contains t wo correlation options tha t exist with this mo del. Douaud enables D ouaud c orrelation ( Equa tion 13.9 in the Theor y Guide ) used f or k nock in SI engines . Gener aliz ed option ( Equa tion 13.10 in the Theor y Guide ) in the k nock mo del r equir e the same par amet ers as in the ignition dela y mo del. 3329Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P age47.4.30. Iner t Dialo g Box The Iner t dialo g box allo ws you t o set the par amet ers r elated t o the iner t mo del. For details , see Setting Up the Iner t Model (p.1735 ). Controls Model allows you t o enable or disable the iner t mo del. Off disables the mo del. Iner t Transp ort enables the iner t mo del. Comp osition Options allows you t o selec t a fix ed H/C r atio or t o sp ecify the c omp osition. Fixed H/C R atio allows you t o sp ecify a fix ed r atio of h ydrogen t o carbon in the H/C R atio field . User S pecified allows you t o sp ecify an arbitr ary comp osition f or the iner t str eam. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3330Task P age R eference GuideComp osition allows you t o set the H/C r atio or the mass fr action. When Fixed H/C R atio is selec ted under Comp osition Options , the f ollowing option(s) ar e available: H/C R atio specifies the fix ed r atio of h ydrogen t o carbon when the Fixed H/C R atio option is enabled . When User S pecified is selec ted under Comp osition Options , the f ollowing option(s) ar e available: Species lists the iner t species name . Mass F raction displa ys the mass fr action of the c orresponding sp ecies . Iner t Species allows you t o sp ecify the name of the iner t species . Add adds the sp ecified iner t species t o the sp ecies list. Remo ve remo ves the sp ecified iner t species fr om the sp ecies list. Normaliz e Species mak es sur e the sp ecies mass fr actions add up t o 1. 3331Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageList A vailable S pecies lists all sp ecies in the ther modynamic da tabase file ( thermo.db ) in the c onsole windo w, 47.4.31. NO x M odel D ialo g Box The NOx M odel dialo g box allo ws you t o set par amet ers r elated t o the NO x postpr ocessor . See Using the NO x Model (p.1823 ) for details ab out the it ems b elow. Controls Models contains tabs f or defining the mo dels used t o calcula te the NO x pr oduc tion. Formation contains the par amet ers t o define the NO x mo del f ormation. Pathw ays contains t oggle butt ons f or enabling the NO x mo dels t o be used f or the c alcula tion of NO and HCN c oncentrations . Thermal NO x enables c alcula tion of ther mal NO x. Prompt NO x enables the c alcula tion of pr ompt NO x. Fuel NO x enables the c alcula tion of fuel NO x.When using the non-pr emix ed c ombustion mo del, the Fuel NO x option is only a vailable if the DPM mo del is also enabled . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3332Task P age R eference GuideN2O In termedia te enables the f ormation of NO x thr ough an N2O in termedia te.This option will only app ear if one of the pr eviously list ed NO x mo dels is enabled . Fuel S treams allows you t o define multiple fuel str eams f or pr ompt NO x and fuel NO x formation. Numb er of F uel S treams sets the numb er of fuel str eams .You ar e allo wed up t o thr ee fuel str eams . Fuel S tream ID specifies the fuel str eam y ou ar e defining in the PDF S tream drop-do wn list , the Fuel S pecies selec tion list , the Prompt tab , and the Fuel tab . PDF S tream specifies the PDF str eam sp ecies asso ciated with a par ticular Fuel S tream ID , when c alcula ting fuel NO x formation in c onjunc tion with the non-pr emix ed c ombustion mo del. You c an selec t either the primar y or secondar y fuel str eams , as defined in the PDF table . Fuel S pecies is a list c ontaining all of the defined sp ecies , which allo ws you t o sp ecify the sp ecies tha t is the fuel asso ciated with a par ticular Fuel S tream ID .You c annot selec t mor e than 5 fuel species f or each fuel str eam, and the t otal numb er of fuel sp ecies selec ted f or all the fuel streams c ombined c annot e xceed 10. Note tha t when the non-pr emix ed c ombustion mo del is enabled , your selec tion in the Fuel S pecies list only applies t o pr ompt NO x calcula tions . Fuel S our ces is a list c ontaining all of the fuel N sour ces.This list is a vailable when Fuel NO x is enabled and your c ase c ontains injec tions with diff erent DPM ma terials defined , such as c ombusting particles and dr oplets . User-D efined F unc tions contains the NOx Rate drop-do wn list , which allo ws you t o use a user-defined func tion (UDF) t o contribut e to the r ate of NO x pr oduc tion. See the separ ate Fluen t Customiza tion M anual for details . Note tha t you ma y also use a UDF t o sp ecify cust om v alues f or the maximum limit ( ) tha t is used f or the in tegration of the t emp erature PDF (when t emp erature is acc oun ted f or in the turbu- lenc e interaction mo deling). Reduc tion allows you t o sp ecify the r educ tion metho ds. Metho ds contains the list of r educ tion metho ds. Rebur n enables the c alcula tion of NO x rebur ning eff ects. SNCR enables the c alcula tion of NO x reduc tion b y the SNCR metho d. Turbulenc e In teraction M ode contains par amet ers r elated t o the eff ect of turbulen t fluc tuations on the NO x formation. See NOx Formation in Turbulen t Flows in the Theor y Guide for details . 3333Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P agePDF M ode is a dr op-do wn list c ontaining options tha t tak e into acc oun t turbulen t fluc tuations when y ou comput e the sp ecified NO x formation. See Setting Turbulenc e Paramet ers (p.1836 ) for details . none specifies the use of laminar NO x rate calcula tions , so tha t the eff ects of turbulenc e are ignor ed. temp erature includes fluc tuations of t emp erature. temp erature/sp ecies includes fluc tuations of the t emp erature and the mass fr action of the sp ecies selec ted in the Species drop-do wn list (which app ears when y ou selec t this option). mix ture fraction includes fluc tuations of the mix ture fraction(s). This is a vailable f or non-pr emix ed c ombustion calcula tions only . PDF Type allows you t o sp ecify the shap e of the PDF . beta models the PDF using Equa tion 14.108 in the Theor y Guide . gaussian models the PDF using Equa tion 14.111 in the Theor y Guide . PDF P oints controls the numb er of p oints at which the b eta func tion in Equa tion 14.105 or Equa tion 14.106 in the Theor y Guide will b e integrated.The default v alue of 10, which indic ates tha t the b eta func tion will b e integrated a t 10 p oints on a hist ogram basis .The default v alue should yield an accur ate solution with a r easonable c omputa tion time . Incr easing this v alue ma y impr ove accur acy, but will also incr ease the c omputa tion time .This field is only a vailable when temp erature or temp erature/sp ecies is selec ted fr om the PDF M ode drop-do wn list. Temp erature Varianc e allows you t o sp ecify the f orm of the tr ansp ort equa tion tha t is solv ed t o calcula te the t emp erature varianc e. algebr aic is an appr oxima te form of the tr ansp ort equa tion (see Equa tion 14.114 in the Theor y Guide ). transp orted solv es Equa tion 14.113 in the Theor y Guide . Tmax Option provides v arious options f or det ermining the maximum limit(s) f or the in tegration of the PDF used t o calcula te the t emp erature. global-tmax sets the limit as the maximum t emp erature in the flo w field . local-tmax-fac tor yields c ell-based maximum t emp erature limits b y multiplying the lo cal cell mean t emp erature by the v alue en tered in Tmax F actor. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3334Task P age R eference Guidespecified-tmax sets the limit f or each c ell to be the v alue en tered in Tmax . user-defined allows you t o ho ok a user-defined func tion tha t specifies cust om v alues f or the maximum limit ( ), which is used f or the in tegration of the t emp erature PDF .This option is only available if y ou ha ve alr eady compiled a user-defined func tion and selec ted it in the Formation tab. Species is a dr op-do wn list tha t app ears when temp erature/sp ecies is selec ted fr om the PDF M ode drop- down list. Here you will selec t the sp ecies whose mass fr action fluc tuations will b e fac tored in to the NO x rate calcula tions . Formation M odel P aramet ers contains the tabs used t o define the NO x pa thw ays. Thermal contains par amet ers f or mo deling ther mal NO x. (The c ontents of this tab will app ear only if Thermal NOx is enabled in the Formation tab .) [O]Model is a dr op-do wn list in which y ou c an selec t the metho d to be used f or calcula tion of ther mal NO x. To cho ose the equilibr ium metho d, selec t equilibr ium .To cho ose the par tial equilibr ium metho d, selec t par tial-equilibr ium .To cho ose the pr edic ted O c oncentration metho d, selec t instan tan- eous . See Metho d 1: Equilibr ium A pproach ,Metho d 2: Partial E quilibr ium A pproach , and Metho d 3: Predic ted O A pproach in the Theor y Guide for details . [OH ]Model is a dr op-do wn list in which y ou c an selec t the metho d to be used f or calcula tion of ther mal NO x. To exclude OH, selec t none .To cho ose the par tial equilibr ium metho d, selec t par tial-equilibr ium . To cho ose the pr edic ted OH c oncentration metho d, selec t instan taneous . See Metho d 1: Exclusion of OH A pproach ,Metho d 2: Partial E quilibr ium A pproach , and Metho d 3: Predic ted OH A pproach in the Theor y Guide for details . UDF R ate provides options f or the tr eatmen t of the NO x pr oduc tion sp ecified b y the user-defined func tion selec ted in the Formation tab . Replac e Fluen t Rate replac es ANSY S Fluen t’s ther mal NO x rate calcula tions with the cust om NO x rate pr oduced by your user-defined func tion. Add t o Fluen t Rate adds the cust om NO x rate pr oduced b y your user-defined func tion t o ANSY S Fluen t’s ther mal NOx rate calcula tions . Prompt contains par amet ers f or mo deling pr ompt NO x. (The c ontents of this tab will app ear only if Prompt NOx is enabled in the Formation tab .) The settings made in this tab will b e asso ciated with a par tic- ular fuel str eam, specified in the Fuel S tream ID field in the Formation tab . Fuel C arb on N umb er specifies the numb er of c arbon a toms p er fuel molecule . 3335Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageEquiv alenc e Ratio is the r atio of the ac tual fuel/air r atio t o the st oichiometr ic fuel/air r atio. UDF R ate provides options f or the tr eatmen t of the NO x pr oduc tion sp ecified b y the user-defined func tion selec ted in the Formation tab . Replac e Fluen t Rate replac es ANSY S Fluen t’s prompt NO x rate calcula tions with the cust om NO x rate pr oduced by your user-defined func tion. Add t o Fluen t Rate adds the cust om NO x rate pr oduced b y your user-defined func tion t o ANSY S Fluen t’s prompt NOx rate calcula tions . Fuel contains par amet ers f or mo deling fuel NO x. (The c ontents of this tab will app ear only if Fuel NO x is enabled in the Formation tab .) The settings made in this tab will b e asso ciated with a par ticular fuel stream, specified in the Fuel S tream ID field in the Formation tab . Fuel Type specifies the t ype of fuel NO x to be calcula ted. Solid enables the c alcula tion of solid fuel NO x. Liquid enables the c alcula tion of liquid fuel NO x. Gas enables the c alcula tion of gas fuel NO x. N In termedia te allows you t o sp ecify an y one of the hcn ,nh3 , or hcn/nh3/no as the in termedia te sp ecies . See Fuel NO x Formation in the Theor y Guide for details . Volatile N M ass F raction specifies the mass fr action of nitr ogen in the v olatiles .This par amet er app ears only f or Solid fuel NOx calcula tions . Fuel N M ass F raction specifies the mass fr action of nitr ogen in the fuel. This par amet er app ears only f or Gas or Liquid fuel NO x calcula tions . Conversion F raction specifies the o verall mass fr action of fuel N (f or gas and liquid fuels), or v olatile N or char N (f or solid fuels), tha t will b e converted t o intermedia te sp ecies and/or pr oduc t NO . Partition F ractions specifies the mass fr action of the c onverted fuel N (f or gas and liquid fuels), or v olatile N or char N (for solid fuels), tha t will b ecome hcn and nh3 .The fr action tha t will b ecome NO will b e calcula ted by the r emainder .This option will app ear only if y ou ha ve selec ted hcn/nh3/no for the N In ter- media te or Char N C onversion drop-do wn lists . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3336Task P age R eference GuideChar N C onversion is a dr op-do wn list in which y ou c an selec t no,hcn ,nh3 , or hcn/nh3/no as the sp ecies t o which the char N is c onverted (when y ou ar e calcula ting solid fuel NO x).This par amet er app ears only for Solid fuel NO x calcula tions . See Setting S olid (C oal) F uel NO x Paramet ers (p.1831 ) for details . Char N M ass F raction specifies the mass fr action of nitr ogen in the char .This par amet er app ears only f or Solid fuel NOx calcula tions . BET S urface Area sets the BET in ternal p ore sur face area (see BET Sur face Area in the Theor y Guide for details) of the par ticles .This par amet er app ears only f or Solid fuel NO x calcula tions . UDF R ate provides options f or the tr eatmen t of the NO x pr oduc tion sp ecified b y the user-defined func tion selec ted in the Formation tab . Replac e Fluen t Rate replac es ANSY S Fluen t’s fuel NO x rate calcula tions with the cust om NO x rate pr oduced b y your user-defined func tion. Add t o Fluen t Rate adds the cust om NO x rate pr oduced b y your user-defined func tion t o ANSY S Fluen t’s fuel NOx rate calcula tions . N2O P ath contains the metho d to be used f or formation of NO thr ough an N2O in termedia te. (The c ontents of this tab will app ear only if N20 In termedia te is enabled in the Formation tab .) N2O M odel contains the dr op-do wn list of a vailable N2O mo dels . quasi-st ead y enables the quasi-st eady-sta te metho d of c alcula tion ( The tr ansp ort equa tion f or the sp ecies N2O will not b e solv ed). transp orted-simple enables the tr ansp orted simple metho d of c alcula tion ( The p ollutan t species N2O is added in the sp ecies list and it ’s mass fr action will b e calcula ted using the tr ansp ort equa tions). UDF R ate provides options f or the tr eatmen t of the NO x pr oduc tion sp ecified b y the user-defined func tion selec ted in the Formation tab . Replac e ANSY S Fluen t Rate replac es the NO x rate calcula ted b y ANSY S Fluen t using N2O in termedia tes with the cust om NOx rate pr oduced b y your user-defined func tion. Add t o ANSY S Fluen t Rate adds the cust om NO x rate pr oduced b y your user-defined func tion t o the NO x rate calcula ted by ANSY S Fluen t using N2O in termedia tes. 3337Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageReduc tion M etho d Paramet ers contains tabs tha t allo w you t o define the metho ds of r educ tion. (These tabs ar e do not app ear unless a reduc tion metho d has b een enabled in the Reduc tion tab .) Rebur n allows you t o define the NO x reduc tion when Rebur n is enabled in the Reduc tion tab . Rebur n M odel contains the dr op-do wn list of r ebur n metho ds. instan taneous[CH ] enables the instan taneous metho d in the Rebur n M odel.When y ou cho ose this metho d a warning t o include CH, CH2, and CH3 will b e displa yed. par tial-equilibr ium activates par tial metho d in the Rebur n M odel. Rebur n Fuel S pecies contains r ebur n fuel sp ecies dr op-do wn list. Equiv alen t Fuel Type contains equiv alen t fuel t ype dr op-do wn list. SNCR allows you t o define the NO x reduc tion when SNCR is enabled in the Reduc tion tab . Injec tion M etho d contains the par amet ers f or NO x reduc tion b y SNCR metho d. gaseous includes ammonia or ur ea as a gas-phase p ollutan t species fr om the injec tion lo cations . liquid includes ammonia or ur ea as a liquid-phase p ollutan t species fr om the injec tion lo cations . Reagen t Species allows you t o sp ecify the r eagen t species as either ammonia ( nh3 ) or ur ea ( co2 ) Reagen t Fraction in S tream allows you t o sp ecify the mass fr action of the r eagen t in the r eagen t str eam. The r emaining mass fraction is assumed t o be water. If you enabled a sec ondar y str eam in y our PDF c alcula tion, by default the sec ondar y str eam will ac t as the r eagen t str eam. Note tha t the Reagen t Fraction in Stream field is only a vailable when using the non-pr emix ed c ombustion mo del with a liquid- phase r eagen t injec tion. Urea D ecomp osition allows you t o sp ecify the dec omp osition mo del t o use when the selec ted Reagen t Species is co2 . rate-limiting specifies tha t the sour ce terms b e calcula ted acc ording t o the r ates giv en in Table 14.3: Two- Step U rea B reakdo wn P rocess. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3338Task P age R eference Guideuser-sp ecified allows you t o sp ecify the molar c onversion fr action f or ammonia, assuming tha t the r est of the ur ea is c onverted t o HNC O. NH3 C onversion is the mole fr action of in the mix ture of and HNC O instan tly cr eated fr om the r eagen t injec tion. The NH3 C onversion field only app ears when user-sp ecified is selec ted f or Urea D e- comp osition . 47.4.32. SOx M odel D ialo g Box The SOx M odel dialo g box allo ws you t o set par amet ers r elated t o the SO x postpr ocessor . See Using the SO x Model (p.1840 ) for details ab out the it ems b elow. Controls Model contains the c ontrol to enable the mo del. 3339Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageSOx Formation enables the mo del. Fuel S treams allows you t o define multiple fuel str eams f or SO x formation. Numb er of F uel S treams sets the numb er of fuel str eams .You ar e allo wed up t o thr ee fuel str eams . Fuel S tream ID specifies the fuel str eam y ou ar e defining in the Fuel S pecies selec tion list and the Formation M odel Paramet ers group b ox. Fuel S pecies is a list c ontaining all of the defined sp ecies .This list is used t o sp ecify the sp ecies tha t is the fuel as- sociated with a par ticular Fuel S tream ID , for an y combustion mo del other than non-pr emix ed combustion. You c annot selec t mor e than 5 fuel sp ecies f or each fuel str eam, and the t otal numb er of fuel sp ecies selec ted f or all the fuel str eams c ombined c annot e xceed 10, the list of fuel sp ecies is available when Gas is the selec ted Fuel Type. Fuel S our ces is a list c ontaining all of the fuel S sour ces.This list is a vailable when Fuel Type is Liquid or Solid and your c ase c ontains injec tions with diff erent DPM ma terials defined , such as c ombusting par ticles and droplets . PDF S tream ID specifies the PDF str eam sp ecies asso ciated with a par ticular Fuel S tream ID , when c alcula ting SOx formation in c onjunc tion with the non-pr emix ed c ombustion mo del. primar y indic ates the pr imar y fuel str eam sp ecies , as defined in the PDF table . secondar y indic ates the sec ondar y fuel str eam sp ecies , as defined in the PDF table . Turbulenc e In teraction M ode contains par amet ers r elated t o the eff ect of turbulen t fluc tuations on the SO x formation. See SOx Formation in Turbulen t Flows in the Theor y Guide for details . PDF M ode is a dr op-do wn list c ontaining options tha t tak e into acc oun t turbulen t fluc tuations when y ou c omput e the sp ecified formation. See Setting Turbulenc e Paramet ers (p.1836 ) for details . none specifies the use of laminar SO x rate calcula tions , so tha t the eff ects of turbulenc e are ignor ed. temp erature includes fluc tuations of t emp erature. temp erature/sp ecies includes fluc tuations of t emp erature and mass fr action of the sp ecies selec ted in the Species drop-do wn list (which app ears when y ou selec t this option). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3340Task P age R eference Guidemix ture fraction includes fluc tuations of the mix ture fraction(s). This is a vailable f or non-pr emix ed c ombustion calcula tions only . PDF Type allows you t o sp ecify the shap e of the PDF . beta models the PDF using Equa tion 14.108 in the Theor y Guide . gaussian models the PDF using Equa tion 14.111 in the Theor y Guide . PDF P oints controls the numb er of p oints at which the b eta func tion in Equa tion 14.105 or Equa tion 14.106 in the Theor y Guide will b e integrated.The default v alue of 10, which indic ates tha t the b eta func tion will b e integrated a t 10 p oints on a hist ogram basis , will yield an accur ate solution with r easonable computa tion time . Incr easing this v alue ma y impr ove accur acy, but will also incr ease the c omputa tion time .This field is only a vailable when temp erature or temp erature/sp ecies is selec ted fr om the PDF Mode drop-do wn list. Temp erature Varianc e allows you t o sp ecify the f orm of tr ansp ort equa tion tha t is solv ed t o calcula te the t emp erature varianc e. algebr aic is an appr oxima te form of the tr ansp ort equa tion (see Equa tion 14.114 in the Theor y Guide ). transp orted solv es Equa tion 14.113 in the Theor y Guide . Tmax Option provides v arious options f or det ermining the maximum limit(s) f or the in tegration of the PDF used to calcula te the t emp erature. global-tmax sets the limit as the maximum t emp erature in the flo w field . local-tmax-fac tor yields c ell-based maximum t emp erature limits b y multiplying the lo cal cell mean t emp erature by the v alue en tered in Tmax F actor. specified-tmax sets the limit f or each c ell to be the v alue en tered in Tmax . user-defined allows you t o ho ok a user-defined func tion tha t specifies cust om v alues f or the maximum limit ( ), which is used f or the in tegration of the t emp erature PDF .This option is only a vailable if you ha ve alr eady compiled a user-defined func tion and selec ted it in the SOx Rate drop-do wn list in the User-D efined F unc tions group b ox. Species is a dr op-do wn list which app ears when temp erature/sp ecies is selec ted fr om the PDF M ode drop- down list. Here you will selec t the sp ecies whose mass fr action fluc tuations will b e fac tored in to the SOx rate calcula tions . 3341Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageUser-D efined F unc tions allows you t o use a user-defined func tion (UDF) t o contribut e to the r ate of SO x pr oduc tion. See the separ ate Fluen t Customiza tion M anual for details . Note tha t you ma y also use a UDF t o sp ecify cust om values f or the maximum limit ( ) tha t is used f or the in tegration of the t emp erature PDF (when t em- perature is acc oun ted f or in the turbulenc e interaction mo deling). SOx Rate allows you t o selec t a c ompiled user-defined func tion. UDF R ate provides options f or the tr eatmen t of the SO x pr oduc tion sp ecified b y the user-defined func tion. Replac e Fluen t Rate replac es ANSY S Fluen t’s SO x rate calcula tions with the cust om SO x rate pr oduced b y your user- defined func tion. Add t o Fluen t Rate adds the cust om SO x rate pr oduced b y your user-defined func tion t o ANSY S Fluen t’s SO x rate calcula tions . Fuel S tream S ettings contains the par amet ers asso ciated with a par ticular fuel str eam of the SO x mo del, as sp ecified in the Fuel S tream ID field in the Fuel S treams group b ox. Fuel Type enables selec tion of the fuel. Solid enables the c alcula tion of solid fuel SO x. Liquid enables the c alcula tion of liquid fuel SO x. Gas enables the c alcula tion of gas fuel SO x. S In termedia te drop-do wn list enables y ou t o selec t intermedia te sp ecies ( h2s ,so2, or h2s/so2 ). Volatile S M ass F raction specifies the mass fr action of sulfur in the v olatiles .This par amet er app ears only f or Solid fuel str eams . Fuel S M ass F raction field sets the v alue f or correct mass fr action of sulfur in the fuel (k g sulfur p er kg fuel). This par amet er app ears only f or Liquid and Gas fuel str eams . Conversion F raction specifies the o verall mass fr action of the fuel S (f or liquid or gas fuels), or the v olatile S or char S (f or solid fuels), tha t will b e converted t o the in termedia te sp ecies and/or pr oduc t SO2.The S In termedia te Conversion F raction has a default v alue of 1. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3342Task P age R eference GuidePartition F ractions specifies the mass fr action of the fuel S (f or liquid or gas fuels), or the v olatile S or char S (f or solid fuels) tha t will b ecome h2s .The r emainder will b ecome SO2.This par amet er only app ears when y ou selec t h2s/so2 for the S In termedia te or Char S C onversion drop-do wn lists . Char S C onversion drop-do wn list selec ts the char S c onversion pa th as so2,h2s , or so2/h2s .This par amet er app ears only f or Solid fuel str eams . Char S M ass F raction specifies the mass fr action of sulfur in the char .This par amet er app ears only f or Solid fuel str eams . Formation M odel P aramet ers allows you t o include SO x pr oduc ts and in termedia tes. Include SO3 P roduc t includes SO3 as a pr oduc t in all of the fuel str eams , as descr ibed in Reaction M echanisms f or Sulfur Oxida tion in the Theor y Guide . Include SH and SO In termediar ies includes SH and SO as in termedia tes in all of the fuel str eams , as descr ibed in Reaction M echanisms for Sulfur O xida tion in the Theor y Guide . [O]Model drop-do wn list sp ecifies the metho d by which O will b e calcula ted in all of the fuel str eams , tha t is, equilibr ium ,par tial-equilibr ium , or instan taneous in the [O] M odel. [OH ]Model drop-do wn list sp ecifies the metho d by which OH will b e calcula ted in all of the fuel str eams , tha t is, equilibr ium ,par tial-equilibr ium , or instan taneous in the [OH] M odel. Imp ortant To use the pr edic ted O and/or OH c oncentration, selec t instan taneous in the [O] Model or [OH] M odel drop-do wn list. 47.4.33. Soot M odel D ialo g Box The Soot M odel dialo g box allo ws you t o set par amet ers r elated t o the so ot mo del. See Using the Soot M odels (p.1854 ) for details ab out the it ems b elow. 3343Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageControls Model specifies which mo del should b e used f or computing so ot formation. Off disables the c alcula tion of so ot formation. One-S tep enables the one-st ep so ot mo del descr ibed in The One-S tep S oot F ormation M odel in the Theor y Guide . Two-Step enables the t wo-st ep so ot mo del descr ibed in The Two-Step S oot F ormation M odel. Moss-Br ookes enables the M oss-B rookes so ot mo del descr ibed in The M oss-B rookes M odel in the Theor y Guide . Moss-Br ookes-H all enables the M oss-B rookes-Hall so ot mo del descr ibed in The M oss-B rookes-Hall M odel in the Theor y Guide .This option is only a vailable when C2H2, C6H6, C6H5, and H2 are pr esen t in the gas phase sp ecies list. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3344Task P age R eference GuideMetho d of M omen t enables the M etho d of M omen t soot mo del descr ibed in Setting U p the M etho d of M omen ts Soot Model (p.1866 ). Species D efinition contains inputs f or sp ecifying the chemic al sp ecies f or y our mo del. Fuel is a dr op-do wn list c ontaining all of the defined sp ecies . Here you will selec t the sp ecies tha t is the fuel f or the One-S tep and Two-Step mo dels , as w ell as the Moss-Br ookes mo del when a pr ecursor species is not iden tified in the defined sp ecies list. Oxidan t is a dr op-do wn list c ontaining all of the defined sp ecies . Here you will selec t the sp ecies tha t is the oxidiz er for the One-S tep and Two-Step mo dels . Precursor fr om allows you t o selec t from a list of sp ecies , enter the c orrelation v alues of sp ecies , or enables y ou t o hook a user-defined func tion, used t o define the user defined pr ecursor sp ecies .This selec tion is available when using the Moss-Br ookes and Moss-Br ookes-H all mo dels . User D efined P recursor allows you t o ho ok a user-defined func tion t o sp ecify the user defined so ot pr ecursor .This selec tion is available when using the Moss-Br ookes and Moss-Br ookes-H all mo dels . Soot P recursor is a selec tion list c ontaining all of the p ossible pr ecursor sp ecies f ound via a quer y of the defined species list. By default , ANSY S Fluen t only c onsiders c2h2 ,c6h6 , and c2h4 as p ossible pr ecursor species . For inf ormation ab out including other sp ecies in the p ossible pr ecursor sp ecies sear ch, contact your ANSY S Fluen t supp ort engineer . From this list y ou will selec t the sp ecies tha t are the so ot pr e- cursor sp ecies f or the Moss-Br ookes,Moss-Br ookes-H all, or Metho d of M omen ts mo dels . Surface Growth is a selec tion list c ontaining all of the p ossible sur face gr owth sp ecies , as e xplained pr eviously f or the Soot P recursor selec tion list. Here you will selec t the sp ecies tha t are the sur face gr owth sp ecies f or the Moss-Br ookes and Moss-Br ookes-H all mo dels . Fuel C arb on N umb er is the numb er of c arbon a toms in the sp ecies selec ted in the Fuel drop-do wn list. This field app ears only f or the Moss-Br ookes and Moss-Br ookes-H all mo del, when user-c orrelation is selec ted in the Precursor fr om drop-do wn list. Fuel H ydrogen N umb er is the numb er of h ydrogen a toms in the sp ecies selec ted in the Fuel drop-do wn list. This field app ears only f or the Moss-Br ookes and Moss-Br ookes-H all mo del, when user-c orrelation is selec ted in the Precursor fr om drop-do wn list. Molecular Weigh t of P recursor is the molecular w eigh t of the pr ecursor sp ecies .This field app ears only f or the Moss-Br ookes and Moss-Br ookes-H all mo del, when user-c orrelation is selec ted in the Precursor fr om drop-do wn list. The default v alue is the w eigh t of ac etylene . 3345Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P agePrecursor C orrelation is a dr op-do wn list y ou c an use t o define a laminar diffusion pr ofile tha t relates mix ture fraction t o precursor mass fr action. This field app ears only f or the Moss-Br ookes and Moss-Br ookes-H all model, when user-c orrelation is selec ted in the Precursor fr om drop-do wn list. piec ewise-p olynomial specifies tha t the pr ecursor mass fr action is a piec ewise-p olynomial func tion of mix ture fraction. The default v alues used b y ANSY S Fluen t correspond t o a methane diffusion flame simula tion, in which b oth the air and fuel initial t emp eratures ar e set t o 290 K, and ac etylene is assumed as the soot pr ecursor .These v alues c an b e revised via the Edit... butt on. constan t specifies tha t the pr ecursor mass fr action is a c onstan t func tion of mix ture fraction, the v alue of which is sp ecified in the field b elow the Precursor C orrelation drop-do wn list. Edit... opens the Piecewise-P olynomial P rofile D ialog Box (p.3404 ) when piec ewise-p olynomial is selec ted from the Precursor C orrelation drop-do wn list , thus allo wing y ou t o revise the default v alues . Stick ing C oefficien ts... (only f or the metho d of momen ts so ot mo del) op ens Sticking C oefficien ts D ialog Box (p.3351 ) wher e you c an pr ovide the c orrection fac tors t o be used f or calcula ting the nuclea tion r ates.This butt on is available only when User P recursor is the selec ted so ot nuclea tion mo del. Turbulenc e In teraction M ode contains inputs tha t specify ho w turbulen t fluc tuations ar e acc oun ted f or in the so ot formation c alcula tions for the Moss-Br ookes and Moss-Br ookes-H all mo dels . For fur ther details on these inputs , see Setting Up the M oss-B rookes M odel and the Hall Ex tension (p.1860 ). PDF M ode is a dr op-do wn list tha t contains the options f or addr essing turbulen t fluc tuations in the so ot rate calcula tions . Note tha t mix ture fraction is the most accur ate option, and should b e used if it is available . none specifies the use of laminar so ot rate calcula tions , so tha t the eff ects of turbulenc e are ignor ed. temp erature specifies tha t the so ot rate calcula tions include the eff ect of t emp erature fluc tuations . temp erature/sp ecies specifies tha t the so ot rate calcula tions include the eff ect of fluc tuations of t emp erature, as w ell as fluc tuations of the mass fr action of the sp ecies selec ted in the Species drop-do wn list (which app ears when y ou selec t this option). mix ture fraction is the most accur ate option, specifying tha t the so ot rate calcula tions include the eff ect of fluc tu- ations of mix ture fraction(s). Note tha t this option is not a vailable if y ou ar e using the edd y-dissip- ation mo del. PDF Type allows you t o sp ecify the shap e of the PDF . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3346Task P age R eference Guidebeta models the PDF using Equa tion 14.108 in the Theor y Guide . gaussian models the PDF using Equa tion 14.111 in the Theor y Guide . PDF P oints controls the numb er of p oints at which the b eta func tion will b e integrated on a hist ogram basis . In- creasing this numb er ma y impr ove accur acy, but will also incr ease c omput e time .This field is only available when temp erature or temp erature/sp ecies is selec ted fr om the PDF M ode drop-do wn list. Temp erature Varianc e allows you t o sp ecify the f orm of tr ansp ort equa tion tha t is solv ed t o calcula te the t emp erature varianc e. algebr aic is an appr oxima te form of the tr ansp ort equa tion (see Equa tion 14.114 in the Theor y Guide ). transp orted solv es Equa tion 14.113 in the Theor y Guide . Tmax Option provides v arious options f or det ermining the maximum limit(s) f or the in tegration of the PDF used to calcula te the t emp erature. global-tmax sets the limit as the maximum t emp erature in the flo w field . local-tmax-fac tor yields c ell-based maximum t emp erature limits b y multiplying the lo cal cell mean t emp erature by the v alue en tered in Tmax F actor. specified-tmax sets the limit f or each c ell to be the v alue en tered in Tmax . user-defined allows you t o ho ok a user-defined func tion tha t specifies cust om v alues f or the maximum limit ( ), which is used f or the in tegration of the t emp erature PDF .This option is only a vailable if you ha ve alr eady compiled a user-defined func tion. Species is a dr op-do wn list which app ears when temp erature/sp ecies is selec ted fr om the PDF M ode drop- down list. Here you will selec t the sp ecies whose mass fr action fluc tuations will b e fac tored in to the soot rate calcula tions . Process P aramet ers contains par amet ers tha t control the c ombustion pr ocess mo deling . Mean D iamet er of S oot P article is the assumed a verage diamet er of the so ot par ticles in the c ombustion sy stem. For the Two-Step model, it is used t o comput e the so ot par ticle mass in Equa tion 14.134 in the Theor y Guide . Mean D ensit y of S oot P article is the assumed a verage densit y of the so ot par ticles in the c ombustion sy stem. For the Two-Step model, it is used t o comput e the so ot par ticle mass in Equa tion 14.134 in the Theor y Guide . For 3347Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P agethe Moss-Br ookes and Moss-Br ookes-H all mo dels , it is in Equa tion 14.141 and in Equa- tion 14.144 in the Theor y Guide .The default v alue supplied b y ANSY S Fluen t is 1800 k g/ (as w as used in the w ork of B rookes and M oss [19] (p.4006 )). Normaliza tion P aramet er for M omen ts (only f or the metho d of momen ts so ot mo del) is used t o solv e the nor maliz ed so ot momen t transp ort equa tions t o minimiz e the numer ical er rors.The default v alue of this input is sufficien t and y ou ma y not need t o change this . Stoichiometr y for S oot C ombustion is the mass st oichiometr y in Equa tion 14.131 in the Theor y Guide , which c omput es the so ot combustion r ate in the One-S tep and Two-Step mo dels .The default v alue supplied b y ANSY S Flu- ent (2.6667) assumes tha t the so ot is pur e carbon and tha t the o xidiz er is O2. Stoichiometr y for F uel C ombustion is the mass st oichiometr y in Equa tion 14.131 in the Theor y Guide , which c omput es the so ot combustion r ate in the One-S tep and Two-Step mo dels .The default v alue supplied b y ANSY S Flu- ent (3.6363) is f or combustion of pr opane (C3H8) by oxygen (O2). Mass of Incipien t Soot P article is in Equa tion 14.142 and Equa tion 14.144 , which is used in the Moss-Br ookes and Moss-Br ookes- Hall mo del c omputa tions .The default v alue supplied b y ANSY S Fluen t (144 k g/mol) is the mass of 12 c arbon a toms . Note tha t for the or iginal implemen tation of the Hall e xtension, the mo del assumed this mass t o be 100 c arbon a toms . Soot O xida tion M odel contains mo del options tha t det ermine the f orm of the so ot o xida tion t erm in the c alcula tions of the Moss-Br ookes and Moss-Br ookes-H all mo dels . Fenimor e-Jones takes in to acc oun t the so ot o xida tion due t o the h ydroxyl radic al. Lee takes in to acc oun t the so ot o xida tion due t o the h ydroxyl radic al and molecular o xygen. User D efined enables y ou t o selec t a user-defined func tion f or so ot o xida tion r ate.This selec tion is a vailable when using the Moss-Br ookes and Moss-Br ookes-H all mo dels . Numb er of M omen ts (only f or the metho d of momen ts so ot mo del) sp ecifies the numb er of momen ts to be used in the Metho d of M omen ts so ot mo del. ANSY S Fluen t will solv e an equal numb er of momen t transp ort equa tions . The default v alue of thr ee momen ts w orks reasonably w ell for wide r ange of pr oblems .You c an sp ecify up t o six momen ts. Soot M echanism (only f or the metho d of momen ts so ot mo del) c ontains so ot mechanism options f or so ot mo deling . Detailed CHEMKIN F ormat allows you t o use a so ot mechanism in CHEMKIN f ormat.To use this option, you must imp ort the so ot mechanism in a CHEMKIN f ormat as descr ibed in Setting U p the M etho d of M omen ts Soot M odel (p.1866 ). See Detailed S oot M echanism in the Fluent Theor y Guide and Setting U p the M etho d of M omen ts Soot Model (p.1866 ) for details ab out this option. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3348Task P age R eference GuideBuilt-In HA CA allows you t o set up the nuclea tion mechanism and use the-built-in HA CA sur face gr owth and o xida- tions mechanisms . See Built-In HA CA M echanism in the Fluent Theor y Guide and Setting U p the Metho d of M omen ts Soot M odel (p.1866 ) for details ab out this option. Soot N uclea tion M odel (only f or the metho d of momen ts so ot mo del) c ontains mo del options r elated t o so ot nuclea tion mo deling . This it em is a vailable only when Built-In HA CA is selec ted. Use P recursor enables y ou t o define the pr ecursor sp ecies .The nuclea tion r ates ar e calcula ted c onsider ing c oagula tion between pr ecursor sp ecies using k inetic theor y. Specify M echanism enables y ou t o sp ecify nuclea tion in t erms of r eactions . User D efined O xida tion R ate allows you t o ho ok the user-defined func tion t o sp ecify the so ot o xida tion r ate.This selec tion is a vailable when using the Moss-Br ookes and Moss-Br ookes-H all mo dels . Model P aramet ers contains par amet ers tha t control the so ot formation mo del. Soot F ormation C onstan t is the par amet er in Equa tion 14.128 in the Theor y Guide .This it em app ears only f or the One-S tep soot mo del. Equiv alenc e Ratio E xponen t is the e xponen t in Equa tion 14.128 in the Theor y Guide .This it em app ears only f or the One-S tep soot mo del. Equiv alenc e Ratio M inimum and Equiv alenc e Ratio M aximum are the minimum and maximum v alues of the fuel equiv alenc e ratio in Equa tion 14.128 in the Theor y Guide .Equa tion 14.128 will b e solv ed only if Equiv alenc e Ratio M inimum < < Equiv alenc e Ratio M aximum ; if is outside of this r ange , ther e is no so ot formation. This it em app ears only f or the One-S tep soot mo del. Activation Temp erature of S oot F ormation R ate is the t erm in Equa tion 14.128 in the Theor y Guide .This it em app ears only f or the One-S tep soot mo del. Magnussen C onstan t for S oot C ombustion is the c onstan t used in the r ate expressions go verning the so ot combustion r ate (Equa tion 14.130 and Equa tion 14.131 ) in the Theor y Guide .This it em app ears only f or the One-S tep and the Two-Step soot mo dels . For the Two-Step mo del, this input will b e called Magnussen C onstan t for S oot and Nuclei C ombustion . Limiting N uclei F ormation R ate is the limiting v alue of the k inetic nuclei f ormation r ate in Equa tion 14.137 in the Theor y Guide . Below this limiting v alue , the br anching and t ermina tion t erm, ( ) in Equa tion 14.136 in the Theor y Guide , is not included .This it em app ears only f or the Two-Step soot mo del. 3349Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageNuclei Br anching-T ermina tion C oefficien t is the t erm in Equa tion 14.136 in the Theor y Guide .This it em app ears only f or the Two-Step soot mo del. Nuclei C oefficien t of Linear Termina tion on S oot is the t erm in Equa tion 14.136 in the Theor y Guide .This it em app ears only f or the Two-Step soot model. Pre-Exponen tial C onstan t of N uclei F ormation is the pr e-exponen tial t erm in the k inetic nuclei f ormation t erm,Equa tion 14.137 in the Theor y Guide .This it em app ears only f or the Two-Step soot mo del. Activation Temp erature of N uclei F ormation R ate is the t erm in the k inetic nuclei f ormation t erm,Equa tion 14.137 in the Theor y Guide .This it em app ears only f or the Two-Step soot mo del. Alpha f or S oot F ormation R ate is , the c onstan t in the so ot formation r ate equa tion, Equa tion 14.134 Two-Step soot mo del. Beta f or S oot F ormation R ate is , the c onstan t in the so ot formation r ate equa tion, Equa tion 14.134 in the Theor y Guide .This it em app ears only f or the Two-Step soot mo del. Magnussen C onstan t for S oot and N uclei C ombustion is the c onstan t used in the r ate expressions go verning the so ot combustion r ate (Equa tion 14.130 and Equa tion 14.131 in the Theor y Guide ).This it em app ears only f or the One-S tep and the Two-Step soot mo dels . [OH] M odel is a dr op-do wn list tha t allo ws you t o sp ecify the metho d by which the OH r adic al concentration is calcula ted, tha t is,instan taneous or par tial-equilibr ium .This list app ears only f or the Moss-Br ookes, Moss-Br ookes-H all, and Metho d of M omen ts soot mo dels . [O] M odel is a dr op-do wn list tha t specifies the metho d by which the O r adic al concentration is c alcula ted, tha t is,equilibr ium ,par tial-equilibr ium , or instan taneous .This list app ears only f or the Moss-Br ookes and the Moss-Br ookes-H all soot mo dels , when y ou ha ve selec ted par tial-equilibr ium for the [OH] Model. Imp ortant To use the c oncentration of OH or O pr edic ted b y the c ombustion mo del, selec t instan taneous for [OH] M odel or [O] M odel. Options contains an option f or mo deling the eff ect of so ot on a v ariable r adia tion absor ption c oefficien t.This group b ox will app ear only when one of the r adia tion mo dels in the Radia tion M odel D ialog Box (p.3269 ) is ac tive. Soot-R adia tion In teraction enables the so ot-radia tion in teraction mo del descr ibed in The E ffect of S oot on the A bsor ption Coefficien t in the Theor y Guide . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3350Task P age R eference GuideSoot S urface Growth Options (only f or the metho d of momen ts so ot mo del) c ontains a par amet er for mo deling the so ot sur face gr owth. This it em is a vailable only when Built-In HA CA is selec ted. Site Densit y is the numb er of sit es/cm2 available on the so ot sur face for sur face gr owth and o xida tion r eactions with the metho d of momen t soot mo del. Enable A ggr ega tion M odel (only f or the metho d of momen ts so ot mo del) enables the mo deling of so ot aggr egates.This it em is available only when Built-In HA CA is selec ted. Critical diamet er is the v alue of the so ot par ticle diamet er ab ove which the c oagula tion r egime is swit ched fr om c o- alesc ent to aggr egate. Fractal dimension is the par amet er tha t descr ibes the aggr egate na ture. For so ot par ticles , a value b etween 1.7 and 2.0 is found t o be reasonably go od. 47.4.34. Stick ing C oefficien ts D ialo g Box The Stick ing C oefficien ts dialo g box allo ws you t o set stick ing c oefficien ts for the so ot mo del with metho d of momen ts. It is op ened fr om the Soot M odel D ialog Box (p.3343 ). See Setting U p the M etho d of M omen ts Soot M odel (p.1866 ) for details ab out using this dialo g box. Controls Species shows the name of the sp ecies f or which y ou sp ecify the Value . 47.4.35. Mechanism D ialo g Box The Mechanism dialo g box allo ws you t o set par amet ers r elated t o nuclea tion r eactions f or the so ot model with metho d of momen ts. It is op ened fr om the Soot M odel D ialog Box (p.3343 ). See Setting U p the M etho d of M omen ts Soot M odel (p.1866 ) for details ab out using this dialo g box. 3351Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageControls Numb er of nuclea tion r eac tions allows you t o sp ecify nuclea tion pr ocess as with a single or multi-st ep r eaction mechanism. For each r e- action, you must sp ecify all appr opriate reaction par amet ers. ID displa ys the ID of the cur rent nuclea tion r eaction setup . Reac tant Species is a dr op-do wn list tha t enables y ou t o selec t the sp ecies f or the cur rent nuclea tion r eaction. Stoich. Coefficien t specifies the st oichiometr ic coefficien t of the r eactant species in the nuclea tion r eaction. Rate Exponen t specifies the r ate constan t for the r eactant species in the cur rent nuclea tion r eaction. Arrhenius R ate contains the inputs f or the A rrhenius r ate par amet ers r elated t o the cur rent nuclea tion r eaction. Pre-exponen tial F actor is the c onstan t in Equa tion 7.9 in the Theor y Guide .The units of must b e sp ecified such tha t the units of the molar r eaction r ate, (Equa tion 7.5 in the Theor y Guide , are moles/v olume-time Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3352Task P age R eference Guide(for e xample , kmol/m3-s) and the units of the v olumetr ic reaction r ate, in Equa tion 7.5 in the Theor y Guide , are mass/v olume-time (f or e xample , kg/m3-s). Imp ortant It is imp ortant to not e tha t if y ou ha ve selec ted the B ritish units sy stem, the A rrhe- nius fac tor should still b e sp ecified in SI units .This is b ecause ANSY S Fluen t applies no c onversion fac tor to the v alue y ou en ter for (the c onversion fac tor is 1.0) when you w ork in B ritish units , as the c orrect conversion fac tor dep ends on y our v alues for , , and so on. Activation E nergy is the c onstan t in the f orward rate constan t expression, Equa tion 7.9 in the Theor y Guide ). Temp erature Exponen t is the v alue f or the c onstan t in Equa tion 7.9 in the Theor y Guide . 47.4.36. Reac tor N etwork Dialo g Box The Reac tor N etwork dialo g box allo ws you t o set par amet ers r elated t o the r eactor net work mo del and c alcula te the r eactor net work for sp ecies tr ansp ort/combustion. See Reactor N etwork Model (p.1680 ) for details ab out using this dialo g box. 3353Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageControls Model contains the option f or enabling (or disabling) the r eactor net work mo del. Reac tor N etwork M odel enables/disables the mo deling of the r eactor net work. Options contains the options f or reactor net work mo del. This p ortion of the dialo g box app ears only if Reac tor Network M odel is selec ted. Imp ort CHEMKIN M echanism allows you t o imp ort a detailed chemic al mechanism in CHEMKIN f ormat. Detailed M echanism M aterial N ame is a dr op-do wn list of a vailable mix ture ma terials fr om which y ou c an selec t a mix ture ma terial for your r eactor net work simula tion. Numb er of Reac tors sets the numb er of r eactors in which c ells ar e gr oup ed based on sp ecified cr iteria. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3354Task P age R eference GuideSolve Temp erature specifies whether or not the r eactor net work algor ithm solv es the t emp erature. By default , this option is selec ted. Expert Option when selec ted, displa ys the ad vanced options r elated t o the solv er settings . Use C urrent Reac tor N etwork allows you t o perform additional r eactor net work simula tions with the e xisting net work of c onnec ted reactors.This option c an b e enabled onc e the F luen t solv er agglomer ates c ells and obtains the r eactor- network solution. Use Time A veraged F ields enables y ou t o selec t the time-a veraged c omp osition fields t o be used f or clust ering r eactors and the time-a veraged v elocity fields f or calcula ting r eactor mass flux ma trix.This option is a vailable only f or unst eady simula tions with enabled Data S ampling F or U nstead y Statistics option. Expert Options contains ad vanced options f or ODE solv er and f or reactor cell clust ering c ontrol.This p ortion of the dialo g box app ears only if Expert Options is selec ted. ODE Rela tive Error Toler anc e specifies r elative error control for ODE in tegrator. ODE A bsolut e Error Toler anc e specifies absolut e error control for ODE in tegrator. Reac tor N etwork Convergenc e Toler anc e allows you t o sp ecify t oler ance to control the accur acy of the r eactor net work calcula tions . Solver allows you t o selec t the solv er for y our simula tion. The default segr egated solv er typic ally c onverges faster than the c oupled solv er. However, if residuals stall ab ove an acc eptable t oler ance, the c oupled solv er should b e used . Maximum N umb er of I terations (segr egated solv er only) sets the maximum numb er of solv er it erations . Maximum In tegration Time (coupled solv er only) sets the maximum elapsed r un time f or ODE solv er. ANSY S Fluen t termina tes the r un a t this time if the r esiduals fail t o converge. Use C ustom F ield F unc tions t o D efine Reac tor Z ones enables the use of cust om field func tions ( Custom F ield F unctions (p.3038 )) for reactor net work cell clust ering. Custom F ield F unc tions contains the list of a vailable user-defined field func tions fr om which y ou c an selec t the func tions f or reactor net work cell clust ering.This selec tion list will not app ear if the Use C ustom F ield F unc tions to D efine Reac tor Z ones option is not selec ted. Calcula te Reac tor N etwork calcula tes a chemic ally r eactive flo w using r eactor net work mo del. 3355Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P age47.4.37. Decoupled D etailed C hemistr y Dialo g Box The Decoupled D etailed C hemistr y dialo g box allo ws you t o postpr ocess slo wly-f orming , trace pol- lutan t sp ecies on a st eady-sta te flo w field using detailed chemic al kinetic mechanisms . Controls Model includes the option t o enable Decoupled D etailed C hemistr y. Imp ort CHEMKIN M echanism... opens the Imp ort CHEMKIN F ormat Mechanism D ialog Box (p.3755 ). Integration P aramet ers... opens the Integration P aramet ers D ialog Box (p.3315 ). Original S pecies are the sp ecies tha t are in the or iginal c ase setup . Pollutan t Species are typic ally slo wly f orming (far fr om chemic al equilibr ium), and o ccur a t miniscule mass fr actions . 47.4.38. Reac ting C hannel M odel D ialo g Box The Reac ting C hannel M odel dialo g box allo ws you t o solv e reacting flo w in shell and tub e hea t ex- changers with long and thin channels . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3356Task P age R eference GuideControls Model includes the option t o Enable Reac ting C hannel M odel. Numb er of B oundar y Groups allows you t o gr oup t ogether channels with c ommon flo w dir ection, mix ture ma terials, inlet c omp ositions , temp erature, pressur e, and mass flo w rate in c ases wher e you ha ve multiple channels . Flow Iterations p er C oupling I teration is the numb er of out er flo w iterations f or each channel flo w iteration. Under-Relaxa tion F actor is used t o up date the hea t flux fr om the r eacting channel. See Equa tion 7.111 in the Theor y Guide . 3357Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageGroup Inde x is used t o iden tify the b oundar y gr oup . Group S ettings contains Group S ettings tha t you will set. Channel Walls in G roup are wall b oundar y zones tha t correspond t o the r eacting channels in the gr oup . Material is the gr oup ma terial. Imp ort CHEMKIN M echanism... opens the Imp ort CHEMKIN F ormat Mechanism D ialog Box (p.3755 ). Model Options allows you t o enable Surface Reac tions and Porous M edium mo dels and set r elated par amet ers. Group Inlet C onditions is wher e you sp ecify the Temp erature, the Flow R ate, the Pressur e, and other inlet c onditions of the reacting channel gr oup . Flow D irection is the X-,Y-, and Z-comp onen t of the flo w at the inlets of the channels in the cur rent group . Species C omp osition is wher e you will sp ecify the inlet mass fr actions of the gr oup . User D efined Inlet C onditions enables y ou t o ho ok a user-defined func tion t o sp ecify the r eacting channel inlet c onditions .When this option is selec ted, the User D efined F unc tion drop-do wn list b ecomes visible . Displa y Reac ting C hannel Variables opens the Reacting C hannel 2D C urves D ialog Box (p.3358 ) for p ostpr ocessing r eacting channel v ariables . 47.4.39. Reac ting C hannel 2D C urves D ialo g Box The Reac ting C hannel 2D C urves dialo g box allo ws you t o displa y or wr ite 2D cur ves of the r eacting channel. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3358Task P age R eference GuideControls Options gives y ou the option t o Plot,Rep ort, or Write to File channel v ariables . Group Inde x is used t o iden tify the r eacting channel b oundar y gr oup . Plot Reac ting C hannel Variables enables the plotting of r eacting channel v ariables . Rep ort Reac ting C hannel Outlet A verage enables the r eporting of r eacting channel outlet a verage. Variable N ame specifies the channel v ariable f or plotting . Variable N ames contains a selec table list of channel v ariables f or reporting . Wall S urfaces contains a selec table list of w all sur faces on which y ou c an plot , report or wr ite the selec ted channel variables . Plot gener ates an X-Y plot. The Plot butt on is a vailable when Plot Reac ting C hannel Variables is selec ted. When the Write to File option is enabled , the Plot butt on changes t o the Write... butt on. 3359Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageRep ort gener ates the r eport of the channel v ariables .The Rep ort butt on is a vailable when Rep ort Reac ting Channel Outlet A verage is selec ted.When the Write to File option is enabled , the Rep ort butt on changes to the Write... butt on. 47.4.40. Discr ete Phase M odel D ialo g Box The Discr ete Phase M odel dialo g box allo ws you t o set par amet ers r elated t o the c alcula tion of a discr ete phase of par ticles . See Modeling D iscrete Phase (p.1911 ) for details . Controls Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3360Task P age R eference GuideInteraction contains par amet ers used f or p erforming c oupled c alcula tions of the c ontinuous and discr ete phase flo w. See Procedur es for a C oupled Two-Phase F low (p.2024 ) for details . Interaction with C ontinuous P hase enables a c oupled c alcula tion of the discr ete phase and the c ontinuous phase . Update DPM S our ces E very Flow Iteration enables c alcula tion of par ticle sour ce terms a t every DPM I teration. For unst eady simula tions , it is the default and is r ecommended . DPM I teration In terval allows you t o control the fr equenc y at which the par ticles ar e tracked and the DPM sour ces ar e up dated. Contour P lots f or DPM Variables contains options f or enabling c ell-a veraged discr ete phase v ariables f or p ostpr ocessing . Mean Values enables additional c ell-a veraged discr ete phase v ariables f or p ostpr ocessing . RMS Values enables additional RMS v alues f or se veral discr ete phase v ariables f or p ostpr ocessing . Particle Treatmen t contains options f or cho osing t o treat the par ticles in an unst eady or a st eady fashion. Unstead y Particle Track ing enables unst eady tracking of par ticles . Track with F luid F low Time S tep enables the use of fluid flo w time st eps t o injec t the par ticles . Injec t Particles a t contains par amet ers t o decide when t o injec t the par ticles f or a new time st ep. Particle Time S tep enables injec tion of par ticles f or e very par ticle time st ep. Fluid F low Time S tep enables injec tion of par ticles f or e very fluid flo w time st ep. In an y case, the par ticles will alw ays be tracked in such a w ay tha t the y coincide with the flo w time of the c ontinuous flo w solv er, as long as the Max. Numb er of S teps (in the Track ing tab) used t o comput e a single tr ajec tory is sufficien t. Particle Time S tep S ize specifies par ticle time st ep siz e for the c alcula tion. Numb er of Time S teps allows you t o sp ecify the numb er of time st eps f or the c alcula tion. Clear P articles clears the par ticles tha t are cur rently in the domain. 3361Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageTrack ing contains t wo par amet ers t o control the time in tegration of the par ticle tr ajec tory equa tions . Track ing P aramet ers contains par amet ers tha t control the tr acking of par ticle tr ajec tories. For st eady-sta te par ticle tr acking, one simple r ule of thumb t o follow when setting the t wo par amet ers b elow is tha t if y ou w ant the particles t o ad vance thr ough a domain of length , the Length Sc ale times the numb er of Max. Numb er of S teps should b e appr oxima tely equal t o . See Integration of P article E qua tion of M otion in the Theor y Guide for details ab out the it ems b elow. Max. Numb er of S teps is the maximum numb er of time st eps used t o comput e a single par ticle tr ajec tory via in tegration of Equa tion 16.1 in the Theor y Guide and Equa tion 16.58 .The default v alue is 50,000 f or st eady- state par ticle tr acking and 500 f or unst eady par ticle tr acking. Specify L ength Sc ale when enabled allo ws you t o sp ecify the length sc ale. Length Sc ale controls the in tegration time st ep siz e used t o integrate the equa tions of motion f or the par ticle . It app ears only when the Specify L ength Sc ale option is enabled . Step L ength F actor specifies the v alue of in Equa tion 24.3 (p.1924 ). Physical M odels contains optional discr ete phase mo dels and their r elevant par amet ers. Options contains additional mo dels tha t can b e included in the c alcula tion. See Physical M odels f or the D iscrete Phase M odel (p.1925 ) for mor e inf ormation. Particle R adia tion In teraction includes the eff ect of r adia tion hea t transf er to the par ticles ( Equa tion 5.34 in the Theor y Guide ). You will also need t o define additional pr operties f or the par ticle ma terials (emissivit y and sc attering factor), as descr ibed in Descr iption of the P roperties (p.2013 ). This it em app ears only if the P-1 or discr ete or dina tes mo del is selec ted in the Radia tion Model D ialog Box (p.3269 ). Thermophor etic F orce enables the inclusion of a ther mophor etic f orce on the par ticles as an additional f orce term. See Thermophor etic F orce in the Theor y Guide for details . Saffman Lif t Force enables the inclusion of S affman ’s lift force (lif t due t o shear) as an additional f orce term. See Saffman ’s Lif t Force in the Theor y Guide for details . Virtual M ass F orce enables the inclusion of vir tual mass f orces in the par ticle f orce balanc e. See Including the Virtual M ass F orce and P ressur e Gradien t Effects on P articles (p.1927 ) for details . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3362Task P age R eference GuidePressur e Gradien t Force enables the inclusion of pr essur e gr adien t eff ects in the par ticle f orce balanc e. See Including the Virtual M ass F orce and P ressur e Gradien t Effects on P articles (p.1927 ) for details . Erosion/A ccretion enables the monit oring of er osion/accr etion r ates a t wall b oundar ies. See Monit oring Erosion/A ccretion of P articles a t Walls (p.1927 ) for details . Pressur e Dependen t Boiling allows you t o swit ch fr om dr oplet v aporization (La w 2) t o boiling (La w 3), as descr ibed in Enabling Pressur e Dependen t Boiling (p.1928 ). Temp erature Dependen t Latent Heat allows you t o include the dr oplet t emp erature eff ects on the la tent hea t, as descr ibed in Equa- tion 16.114 in the Theor y Guide . Two-W ay Turbulenc e Coupling enables the eff ect of change in turbulen t quan tities due t o par ticle damping and turbulenc e eddies . DEM C ollision allows you t o mo del DEM c ollision as descr ibed in Modeling C ollision U sing the DEM M odel (p.1930 ). Stochastic C ollision enables the eff ect of dr oplet c ollisions , as descr ibed in Collision and D roplet C oalesc ence Model Theor y in the Theor y Guide . Coalesc enc e enables the eff ect of dr oplet c oalesc ence, as descr ibed in Collision and D roplet C oalesc ence Model Theor y in the Theor y Guide .This option is a vailable when the Stochastic C ollision option is enabled . Break up enables br eakup f or all suitable injec tions .You c an selec t the br eakup mo del and par amet ers, or disable br eakup, for each injec tion in the Set Injec tion P roperties D ialog Box (p.3917 ). Child P article Treatmen t contains an option t o Consider C hildr en in the S ame Track ing S tep.This c ontrol app ears only when either Break up is enabled under Options or wall-film is selec ted f or Boundar y Cond .Type in the DPM tab of the Wall dialo g box. DEM C ollision M odel contains mo del settings tha t allo w you t o continue y our setup of the mo del. Adaptiv e Collision M esh Width is enabled b y default. This adjusts the width of the c ollision mesh t o the lar gest par cel diamet er multiplied b y the Edge Sc ale F actor Edge Sc ale F actor is the fac tor b y which the width of the c ollision mesh is adjust ed t o the lar gest par cel diamet er. Static C ollision M esh Width is the fix ed width of the c ollision mesh. This app ears when the Adaptiv e Collision M esh Width is disabled . 3363Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageMaximum P article Velocity limits the maximum par ticle v elocity to a ph ysically plausible r ange . DEM C ollisions ... opens the DEM C ollisions D ialog Box (p.3367 ).This butt on is a vailable a t the b ottom of the Discr ete Phase M odel dialo g box when the DEM C ollision mo del is enabled . UDF contains par amet ers tha t can b e used t o cust omiz e the discr ete phase mo del using a user-defined func tion. See the separ ate Fluen t Customiza tion M anual for details ab out user-defined func tions . User-D efined F unc tions lists will sho w available user-defined func tions tha t can b e selec ted t o cust omiz e the discr ete phase model. Body Force contains a dr op-do wn list of user-defined func tions a vailable f or including additional b ody forces. Erosion/A ccretion contains a dr op-do wn list of user-defined func tions a vailable f or inc orporating non-standar d erosion r ate definitions .This it em will app ear only when the Erosion/A ccretion option has b een enabled . Scalar U pdate contains a dr op-do wn list of user-defined func tions a vailable f or calcula ting or in tegrating sc alar values along the par ticle tr ajec tory. Sour ce contains a dr op-do wn list of user-defined func tions a vailable f or mo difying in terphase e xchange terms. Spray Collide F unc tion contains a dr op-do wn list of user-defined func tions a vailable f or mo difying spr ay collide func tion. DPM Timest ep contains a dr op-do wn list of user-defined func tions a vailable f or mo difying DPM time st ep. Impingemen t Model contains a dr op-do wn list of user-defined func tions a vailable f or mo difying the impingemen t model. If selec ted, the Impingemen t Model UDF will o verwrite the impingemen t/splashing model selec ted f or the Lagr angian or E uler ian w all film b oundar y condition. This it em is a vailable only when either wall-film is selec ted f or Boundar y Cond .Type in the DPM tab of the Wall dialo g box or the Euler ian Wall F ilm mo del is enabled . Film Regime contains a dr op-do wn list of user-defined func tions a vailable f or setting the film r egime of par ticle impingemen t.This it em is a vailable only when either wall-film is selec ted f or Boundar y Cond . Type in the DPM tab of the Wall dialo g box or the Euler ian Wall F ilm mo del is enabled . Splashing D istribution contains a dr op-do wn list of user-defined func tions a vailable f or mo difying distr ibution of splashed particle v ariables . If selec ted, the Splashing D istribution UDF will o verwrite the impinge- men t/splashing mo del selec ted f or the Lagr angian or E uler ian w all film b oundar y condition. This Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3364Task P age R eference Guideitem is a vailable only when either wall-film is selec ted f or Boundar y Cond .Type in the DPM tab of the Wall dialo g box or the Euler ian Wall F ilm mo del is enabled . User Variables lists the user input v ariables . Numb er of Sc alars sets the numb er of sc alar v alues used in the c alcula tions with user-defined func tions . Numer ics tab giv es y ou c ontrol over the numer ical schemes f or par ticle tr acking as w ell as solutions of hea t and mass equa tions . See Numer ics of the D iscrete Phase M odel (p.1937 ) for details . Track ing Options contains par amet ers of solutions of hea t and mass equa tions . Accur acy Control enables the solution of equa tions of motion within a sp ecified t oler ance. Toler anc e is the maximum r elative error tha t has t o be achie ved b y the tr acking pr ocedur e. Max. Refinemen ts is the maximum numb er of st ep siz e refinemen ts in one single in tegration st ep. If this numb er is exceeded the in tegration will b e conduc ted with the last r efined in tegration st ep siz e. Track in A bsolut e Frame enables tr acking the par ticles in the absolut e reference frame . Track ing Scheme S elec tion contains par amet ers f or selec tion of numer ical schemes . Automa ted enables a mechanism t o swit ch in an aut oma ted fashion b etween numer ically stable lo wer or der schemes and higher or der schemes , which ar e stable only in a limit ed r ange . High Or der Scheme can b e chosen fr om the gr oup c onsisting of trapezoidal and runge-k utta scheme . Low Or der Scheme consists of implicit and the e xponen tial analytic integration scheme . Track ing Scheme allows you t o cho ose an y of the tr acking schemes .You also c an c ombine each of the tr acking schemes with A ccur acy Control. It is selec table only if Automa ted is swit ched off . Coupled H eat-M ass S olution enables the solution of the c orresponding equa tions using a c oupled ODE solv er with er ror toler ance control for the Droplet ,Combusting , or Multic omp onen t par ticles . See Including C oupled H eat- Mass S olution E ffects on the P articles (p.1940 ) for details . Vaporizing Limiting F actors for the Mass and Heat are set a t the default v alues of 0.3 and 0.1, respectively. See Including C oupled Heat-Mass S olution E ffects on the P articles (p.1940 ) for details . 3365Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageAveraging contains settings f or no de based a veraging of DPM quan tities . See Node B ased A veraging of Particle D ata (p.1941 ) for details . Enable N ode B ased A veraging enables no de based a veraging and displa ys additional r elated options . For non-DDPM c ases , this option is not a vailable when the Linear ize Sour ce Terms is selec ted. Average DPM S our ce Terms enables a veraging of sour ce terms f or the discr ete phase . Average in E ach In tegration Time S tep enables a verages dur ing each in tegration time st ep. Average DDPM Variables enables a veraging of DDPM v ariables when the DDPM mo del is ac tive. Kernel S ettings contains settings f or the k ernel used b y the no de based a veraging algor ithm. Averaging K ernel selec ts the k ernel t o use f or a veraging Gaussian F actor sets the c onstan t for the G aussian distr ibution when gaussian is selec ted f or Averaging K ernel. Sour ce Terms Linear ize Sour ce Terms enables the linear ization of sour ce terms f or the discr ete phase . For non-DDPM c ases , this option is not a vailable when the Enable N ode B ased A veraging is selec ted. Parallel contains par amet ers tha t control the c omput e no des f or p erforming discr ete phase c alcula tions in par allel. See Parallel P rocessing f or the D iscrete Phase M odel (p.2066 ) for details . Metho ds allows you t o selec t the mo de f or par allel pr ocessing . Message P assing enables clust er computing and also w orks on shar ed-memor y machines .With this option, the comput e no de pr ocesses themselv es p erform the par ticle w ork on their lo cal par titions and particle migr ation t o other c omput e no des is implemen ted using message passing pr imitiv es. No special r equir emen ts ar e plac ed on the host machine . Note tha t this mo del is not a vailable if the Cloud M odel option is enabled in the Turbulen t Dispersion tab of the Set Injec tion P roperties dialo g box. Shared M emor y allows you t o sp ecify par amet ers f or p erforming the c alcula tions on shar ed-memor y multipr ocessor machines . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3366Task P age R eference GuideHybr id allows you t o combine Message P assing (as pr eviously descr ibed) and OpenMP for a d ynamic load balancing without migr ation of c ells.This option enables multic ore clust er computing , and also w orks on shar ed-memor y machines .When using the Hybr id option, you c an c ontrol the maximum numb er of thr eads on each machine via the Thread C ontrol dialo g box (see Controlling the Threads (p.3095 ) for details). Note tha t this option is not a vailable if the Cloud M odel option is enabled in the Turbulen t Dispersion tab of the Set Injec tion P roperties dialo g box. Shared M emor y Options contains settings f or the Shared M emor y option. This gr oup b ox is only a vailable on Linux, when the Shared M emor y is selec ted fr om the Metho ds list. Workpile A lgor ithm specifies tha t the discr ete phase c alcula tions ar e to be performed on a shar ed-memor y multipr o- cessor machine . Numb er of Threads specifies the numb er of thr eads t o be used in p erforming the par ticle c alcula tions . By default , this paramet er is equal t o the numb er of c omput e no des y ou sp ecified f or the par allel solv er. (This item app ears only if Workpile A lgor ithm is enabled .) Hybr id Options contains settings f or the Hybr id option. This gr oup b ox is only a vailable if Hybr id is selec ted fr om the Metho ds list. Use DPM D omain enables the use of a separ ate computa tional domain f or par ticle tr acking, which impr oves load balancing and sc alabilit y at the e xpense of some additional memor y overhead . 47.4.41. DEM C ollisions D ialo g Box The DEM C ollisions dialo g box allo ws you t o manage the c ollision par tners . Controls 3367Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageCollision P artners contains a list fr om which y ou c an selec t one or mor e collision par tners in or der t o set , create, copy, rename , delet e, or list. Create creates a new c ollision par tner and op ens the Create Collision P artner D ialog Box (p.3368 ), in which y ou can en ter the c ollision par tner name . Copy creates a new injec tion with the same pr operties as the selec ted c ollision par tner and op ens the Copy Collision P artner D ialog Box (p.3368 ). Rename allows you t o change the name of the c ollision par tner . It op ens the Copy Collision P artner D ialog Box (p.3368 ). Delet e delet es the c ollision par tner selec ted in the Collision P artners list. List lists the c ollision par tners with their c orresponding la ws. Set... opens the DEM C ollision S ettings D ialog Box (p.3369 ) for the c ollision par tner selec ted in the Collision Partners list. 47.4.42. Create Collision P artner D ialo g Box The Create Collision P artner dialo g box allo ws you t o sp ecify the name of the c ollision par tner . Controls Name is the name of the c ollision par tner b eing cr eated. 47.4.43. Copy Collision P artner D ialo g Box The Copy Collision P artner dialo g box allo ws you t o copy the selec ted c ollision par tner . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3368Task P age R eference GuideControls Name is the name of the new c ollision par tner c opied fr om the selec ted par tner . 47.4.44. Rename C ollision P artner D ialo g Box The Rename C ollision P artner dialo g box allo ws you t o rename the selec ted c ollision par tner . Controls Name is the new name of the c ollision par tner selec ted in the list. 47.4.45. DEM C ollision S ettings D ialo g Box The DEM C ollision S ettings dialo g box allo ws you t o sp ecify the c ollision la ws of the c ollision par tners . Controls Collision P air contains the list of cr eated c ollision par tners . Contact Force Laws is wher e you will define the c ollisions la ws. Normal allows you t o cho ose b etween spring,spring-dashp ot,her tzian , and her tzian-dashp ot.You c an also cho ose none if you do not w ant to include a c ontact force. 3369Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageTangen tial allows you t o cho ose b etween the friction-dhsf and friction-dshf-r olling force laws.You c an also exclude a f orce law, in which c ase y ou w ould selec t none . Constan ts contains the list of c ontact force constan ts. Depending on the c ontact force law in eff ect, diff erent constan ts will b e visible . 47.4.46. Solidific ation and M elting D ialo g Box The Solidific ation and M elting dialo g box allo ws you t o set par amet ers r elated t o the solidific ation/melt- ing mo del. See Modeling S olidific ation and M elting (p.2321 ) for details ab out the it ems b elow. Controls Model contains the option f or tur ning on the mo del. Solidific ation/M elting enables/disables the mo deling of solidific ation and/or melting . Options gives y ou the option of selec ting one of t wo mo del r ules . Lever R ule allows you t o use the L ever rule ( Equa tion 20.14 in the Theor y Guide ). Scheil R ule allows you t o use the Scheil r ule ( Equa tion 20.18 in the Theor y Guide ). If you selec t Scheil R ule, then you c an enable Back D iffusion . Enter either a constan t or a user-defined func tion t o sp ecify the v alue of the Back D iffusion P aramet er, used in Equa tion 20.19 to Equa tion 20.21 in the Theor y Guide . Refer to DEFINE_SOLIDIFICATION_PARAMS of the Fluen t Customiza tion M anual for detailed in- formation ab out the user-defined func tion. Paramet ers contains par amet ers r elated t o the solidific ation/melting mo del. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3370Task P age R eference GuideMush y Zone C onstan t sets the v alue of in Equa tion 20.6 in the Theor y Guide . Include Thermal Buo yanc y includes the gr avitational f orce due t o the v ariation of densit y with t emp erature. Refer to Thermal and S olutal B uoyancy in the Theor y Guide for mor e inf ormation. Note This option is a vailable only when solidific ation is mo deled with sp ecies tr ansp ort. Include S olutal Buo yanc y includes the gr avitational f orce due t o the v ariation of densit y with the change in the sp ecies c om- position of the melt. Refer to Thermal and S olutal B uoyancy in the Theor y Guide for mor e inf ormation. Note This option is a vailable only when solidific ation is mo deled with sp ecies tr ansp ort. Include P ull Velocities includes pull v elocities in the mo del, as descr ibed in Momen tum E qua tions and Pull Velocity for Continuous C asting in the Theor y Guide . Comput e Pull Velocities enables the c alcula tion of pull v elocities based on the sp ecified v elocity boundar y conditions , as de- scribed in Pull Velocity for C ontinuous C asting in the Theor y Guide .This option app ears when Include Pull Velocities is tur ned on. Flow Iterations p er P ull Velocity Iteration specifies the numb er of times the pull v elocity equa tions will b e solv ed af ter each it eration of the solv er.This option app ears when Comput e Pull Velocities is tur ned on. 47.4.47. Acoustics M odel D ialo g Box The Acoustics M odels dialo g box allo ws you t o set par amet ers r elated t o the ac oustics mo del. See Using the Ff owcs Williams and Ha wkings A coustics M odel (p.1877 ) for details ab out the it ems b elow. 3371Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageControls Model contains the option f or tur ning on the ac oustics mo del. Off disables the ac oustics mo del. Wave Equa tion enables the w ave equa tion mo del. See Using the A coustics Wave Equa tion M odel (p.1902 ) for details . Ffowcs-W illiams & H awkings enables the Ff owcs Williams and Ha wkings (FW-H) ac oustics mo del. See Postpr ocessing the FW-H Acoustics M odel D ata (p.1891 ) for details . Broadband N oise S our ces enables the br oadband noise ac oustics mo del. See Using the B roadband N oise S ource Models (p.1908 ) for details . Export Options contains the par amet ers r elated t o exporting ac oustics da ta. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3372Task P age R eference GuideExport Acoustic S our ce Data in ASD F ormat enables/disables the sa ving of sour ce da ta files in ASD f ormat. Export Acoustic S our ce Data in C GNS F ormat enables/disables the sa ving of sour ce da ta files in C GNS f ormat. Comput e Acoustics S ignals S imultaneously enables “on-the-fly ” calcula tion of sound .When this option is chosen, the ANSY S Fluen t console windo w will pr int a message a t the end of each time st ep indic ating tha t the sound pr essur e signals have been c omput ed (f or e xample ,Extracting sound signals at x receiver loca- tions... , wher e x is the numb er of r eceivers y ou sp ecified). Enabling this option instr ucts ANSY S Fluen t to comput e sound pr essur e signals a t the end of each time st ep, which will sligh tly incr ease the c omputa tion time . Wave Equa tion Options contains options f or the w ave equa tion. Time-F ilter S ounds S our ces enables/disables the filt ering of sounds sour ces Sour ce M ask UDF Specifies a UDF f or the sour ce mask. Sponge L ayer UDF Specifies a UDF f or the sp onge la yer. Basic S hap es... opens the Basic S hap es D ialog Box (p.3377 ), which allo ws you t o sp ecify shap es for sour ce mask and sponge la yer geometr y. Ffowcs-W illiams & H awkings Options contains the Convective Effects option, which should b e enabled f or all c ases dealing with e xternal flo ws around b odies .When this option is enabled , you will need t o sp ecify the pr oper Free S tream Velocity and Free S tream D irection . Define S our ces... opens the Acoustic S ources D ialog Box (p.3374 ), which allo ws you t o sp ecify the ac oustics sour ces. Define Rec eivers... opens the Acoustic R eceivers D ialog Box (p.3376 ), which allo ws you t o sp ecify the lo cation of the r eceivers. Model C onstan ts contains par amet ers r elated t o the ac oustics mo del. Far-F ield D ensit y sets the v alue of the far-field fluid densit y ( in Equa tion 15.1 in the Theor y Guide ). Far-F ield S ound S peed sets the sp eed of the sound a t the far-field ( in Equa tion 15.5 and Equa tion 15.6 in the Theor y Guide ). Artificial Visc osit y Factor f or S ponge L ayer Set the A rtificial Viscosity Factor for S ponge La yer. 3373Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageFree S tream Velocity is available when the Convective Effects option f or the Ffowcs-W illiams & H awkings mo del is en- abled . Free S tream D irection is available when the Convective Effects option f or the Ffowcs-W illiams & H awkings mo del is en- abled . Referenc e Acoustic P ressur e is used t o calcula te the sound pr essur e level in dB . Referenc e Acoustic P ower is used t o non-dimensionaliz e the ac oustic p ower, giving the sound pr essur e level in dB (see Fast F ourier Transf orm (FFT ) Postpr ocessing (p.2898 )).This par amet er is equal t o W for airb orne sound and W for under water sound . Referenc e Acoustic In tensit y is defined as , although this quan tity is not cur rently used b y ANSY S Fluen t. Sour ce Correlation L ength is requir ed when sound is t o be comput ed using a 2D flo w result. The FW-H in tegrals will b e evalua ted over this length in the depthwise dir ection using the iden tical sour ce da ta. Numb er of Realiza tions is the numb er of times the noise sour ce terms will b e comput ed thr ough the gener ation of stochastic turbulen t velocity field . Numb er of F our ier M odes is the numb er of t erms in the F ourier summa tion fr om which the turbulen t velocity field and its der iv- atives ar e comput ed. Numb er of Time S teps P er Re volution is available only f or st eady-sta te cases tha t ha ve a single mo ving r eference frame . Here you will sp ecify the numb er of equiv alen t time st eps tha t it will tak e for the r otating z one t o complet e one r evolution. Numb er of Re volutions is available only f or st eady-sta te cases tha t ha ve a single mo ving r eference frame . Here you will sp ecify the numb er of r evolutions tha t will b e simula ted in the mo del. Apply saves the ac oustics mo del settings . 47.4.48. Acoustic S our ces D ialo g Box The Acoustic S our ces dialo g box allo ws you t o sp ecify the ac oustics sour ces. See Using the Ff owcs Williams and Ha wkings A coustics M odel (p.1877 ) for details ab out the it ems b elow. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3374Task P age R eference GuideControls Sour ce Zones contains a list of z ones fr om which y ou c an selec t one or mor e emission (sour ce) sur faces. Type contains a list of all p ossible t ypes of z ones fr om which y ou c an selec t one or mor e types of the a vailable zones . If you selec t an a vailable t ype of z one , the r elevant zones will then b e selec ted in the Sour ce Zones list. If you sp ecify an y valid interior zones as sour ce sur faces, the Interior C ell Z one S elec tion D ialog Box (p.3378 ) will app ear. File N ame is used t o giv e the names of the sour ce da ta files (f or e xample ,acoustic_example_xxxx.asd , wher e xxxx is the global time-st ep inde x of the tr ansien t solution) and an inde x file (f or e xample , acoustic_example.index ) tha t will st ore the inf ormation asso ciated with the sour ce da ta. Write Frequenc y allows you t o control ho w of ten the sour ce da ta will b e wr itten.This will enable y ou t o sa ve disk spac e if the time-st ep siz e used in the tr ansien t flo w simula tion is smaller than nec essar y to resolv e the sound fr equenc y you ar e attempting t o pr edic t. Numb er of Time S teps p er F ile allows you t o wr ite the sour ce da ta to multiple files , each c ontaining the sour ce da ta for a numb er of time st eps sp ecified b y you. Rec eivers... opens the Acoustic R eceivers D ialog Box (p.3376 ), which allo ws you t o sp ecify the lo cation of the r eceivers. 3375Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P age47.4.49. Acoustic Rec eivers D ialo g Box The Acoustic Rec eivers dialo g box allo ws you t o sp ecify the lo cation of the ac oustic r eceivers. See Using the Ff owcs Williams and Ha wkings A coustics M odel (p.1877 ) for details ab out the it ems b elow. Controls Moving Rec eivers allows you t o sp ecify the lo cations of the mo ving r eceivers. Moving Rec eiver S ettings allows you t o sp ecify the Velocity and the Direction of the mo ving r eceivers. Numb er of Rec eivers allows you t o sp ecify the t otal numb er of r eceivers f or which y ou w ant to comput e sound . Name shows the name of the r eceiver. If you edit the field , the new name will tak e eff ect after you click the OK butt on. X-C oord.,Y-C oord., Z-C oord. specifies the c oordina tes for each r eceiver. Note tha t because ANSY S Fluen t’s acoustics mo del is ideally suited f or far-field noise pr edic tion, the r eceiver lo cations y ou define should b e at a r easonable distanc e from the sour ces of sound (tha t is, the selec ted ac oustic sur face), and c an fall outside of the c omputa tional domain if needed . Signal F ile N ame specifies the name of the file used t o store sound pr essur e signals f or the c orresponding r eceivers. By default , the files will b e named receiver-1.dat ,receiver-2.dat , and so on. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3376Task P age R eference Guide47.4.50. Basic S hap es D ialo g Box The B asic S hap es dialo g box allo ws you t o selec t shap es for use as sour ce mask and sp onge la yer geometr y. Figur e 47.1: The B asic S hap es D ialo g Box Controls Region Regist ers contains a list of all r egist ers which ha ve been cr eated f or use as geometr ic shap es. Properties displa ys inf ormation ab out the selec ted r egion r egist er. Use S hap e for S our ce M ask enables/disables the use of the selec ted r egion r egist er as a sour ce mask. Transition Thick ness of S our ce M ask Specifies tr ansition thick ness of sour ce mask. Use S hap e for S ponge L ayer enables/disables the use of the selec ted r egion r egist er as a sp onge la yer. Transition Thick ness of S ponge L ayer Specifies tr ansition thick ness of sp onge la yer. 3377Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P age47.4.51. Interior C ell Z one S elec tion D ialo g Box The Interior C ell Z one S elec tion dialo g box allo ws you t o sp ecify the ac oustics sour ces. See Specifying Source Sur faces (p.1884 ) for details ab out the it ems b elow. Controls Sour ce Surface displa ys the selec ted in terior sur face. Interior C ell Z one contains a list of t wo interior c ell z ones , from which y ou will selec t the z one tha t is o ccupied b y the quadr upole sour ces. 47.4.52. Structural M odel D ialo g Box The Structural M odel dialo g box allo ws you t o enable str uctural mo del c alcula tions as par t of an in- trinsic fluid-str ucture in teraction (FSI) pr oblem. For details , see Modeling F luid-S tructure In teraction (FSI) Within F luen t (p.2329 ). Controls Model indic ates which mo del, if an y, is used f or the str uctural mo del c alcula tions . Off disables str uctural mo del c alcula tions . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3378Task P age R eference GuideLinear E lasticit y enables str uctural calcula tions f or the solid c ell z one such tha t the in ternal load is linear ly pr oportional to the no dal displac emen t, and the str uctural stiffness ma trix remains c onstan t.This mo del is appr o- priate when the str ess loading do es not e xceed the yield str ength of the solid ma terial. 47.4.53. Euler ian Wall F ilm D ialo g Box The Euler ian Wall F ilm dialo g box allo ws you t o set v arious mo del and solution metho d controls f or the E uler ian Wall F ilm mo del. For mor e inf ormation, see Modeling E uler ian Wall F ilms (p.2337 ). Controls Euler ian Wall F ilm enables/disables the use of the E uler ian Wall F ilm mo del in the c alcula tions . 3379Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageModel Options and S etup contains c ontrols f or sp ecific solution, discr ete phase mo del (DPM), and ma terial options f or the E uler ian Wall F ilm mo del. Solution Options includes options f or enabling/disabling the momen tum equa tion and DPM c alcula tions . Solve M omen tum allows the momen tum equa tion (see Equa tion 22.2 in the Fluent Theor y Guide ) to be solv ed. Solve Energy allows the ener gy equa tion (see Equa tion 22.3 in the Fluent Theor y Guide ) to be solv ed. Solve Sc alar allows the passiv e sc alar equa tion (see Equa tion 22.38 in the Fluent Theor y Guide ) to be solv ed. Onc e you enable this option, you c an set Scalar D iffusivit y. DPM C ollec tion allows for the eff ect of discr ete par ticle str eams or discr ete par ticles hitting a fac e on a w all boundar y tha t are then absorb ed in to the film. Onc e enabled , the Particle S plashing ,Particle Stripping , and Edge S epar ation options b ecome a vailable (see DPM C ollec tion in the Theor y Guide (p.1)). In addition, you c an also set Impingemen t Paramet ers in the Wall D ialog Box (p.3549 ). Particle S plashing (available when DPM C ollec tion is enabled) enables par ticle splashing globally .You c an sp ecify splashing options on selec ted film w all b oundar ies in the Wall D ialog Box (p.3549 ). Particle S tripping (available when DPM C ollec tion is enabled) allo ws you t o set the Critical S hear S tress,Diamet er Coefficien t, and Mass C oefficien t, available under Stripping Options . Edge S epar ation (available when DPM C ollec tion is enabled) allo ws you t o set the Critical Weber N umb er,Crit- ical A ngle , and Separ ation M odel, available under Separ ation Options . Treat Sharp Edge allows you t o set the Sharp Edge A ngle when handling the eff ects of shar p edges and the w all film. Phase A ccretion (available when the E uler ian M ultiphase or M ixture (with S lip Velocity) mo del is enabled) allo ws for the in teraction of the w all film with a sec ondar y phase in a multiphase flo w. Onc e enabled , the Phase C onc entration and Phase Velocity can b e set under Phase A ccretion Options (see Secondar y Phase A ccretion in the Theor y Guide (p.1)). Phase C hange allows you t o acc oun t for phase changes b etween the film ma terial (liquid) and the gas sp ecies (vapor).When this option is selec ted, you c an sp ecify the phase change par amet ers on the selec ted film w all b oundar ies in the Wall F ilm tab of the Wall D ialog Box (p.3549 ). (See Coupling of Wall Film with M ixture Species Transp ort in the Fluent Theor y Guide ). Momen tum Options are available when the Solve M omen tum option is enabled . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3380Task P age R eference GuideGravity Force is the sec ond t erm on the r ight hand side of Equa tion 22.2 , and is r esponsible f or acc elerating the film in the dir ection of gr avity comp onen t tha t is par allel t o the w all. Surface Shear F orce is the thir d term on the r ight hand side of Equa tion 22.2 , and is r esponsible f or acc elerating the film in the dir ection of the e xternal flo w. Pressur e Gradien t is the first t erm on the r ight hand side of Equa tion 22.2 , and is the t erm acc elerating the film in the dir ection opp osing the gr adien t in e xternal pr essur e. For e xample , if a film on the sur face of a wing is b eing mo deled and ther e is a high pr essur e region a t the leading edge with lo w pr essur e on the t op of the wing , this t erm will t end t o mo ve a unif orm film t owards the lo w pr essur e region on the t op of the wing . Spreading Term is the term on the r ight hand side of Equa tion 22.2 , and is r esponsible f or spr eading .This t erm will acc elerate the flo w in the dir ection opp osing the gr adien t in heigh t, mo ving the film t owards regions of lo wer thick ness .This t erm b ecomes a vailable only when b oth Pressur e Gradien t and Gravity Term are selec ted. Surface Tension is the term on the r ight hand side of Equa tion 22.2 .This t erm b ecomes a vailable only when Pressur e Gradien t is selec ted. Sharp Edge A ngle allows you t o acc oun t for shar p edges alongside the w all film, when the Treat Sharp Edge option is enabled . Material Options allows you t o apply ma terial pr operties t o the w all film mo del. Film M aterial is the ma terial assigned t o the w all film. Film Vapor M aterial (available only when Phase C hange is selec ted) is the ma terial assigned t o the w all film v apor. Surface Tension is the sur face tension f or the designa ted w all film ma terial. Separ ation Options (available when DPM C ollec tion and Edge S epar ation are enabled) allo ws you t o set DPM par ticle separ ation options (see Film S epar ation in the Theor y Guide (p.1)). Critical Weber N umb er is the cr itical value f or the Weber numb er. Separ ation A ngle is the cr itical angle , θ, tha t separ ation o ccurs . Separ ation M odel allows you t o sp ecify one of thr ee diff erent mo dels t o calcula te the numb er and diamet er of the shed par ticle str eam a t an edge onc e separ ation o ccurs . Available mo dels include: Fouc art (the 3381Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P agedefault , see Foucart Separ ation in the Theor y Guide (p.1)),O'Rour ke (see O’Rourke Separ ation ), and Friedr ich (see Friedr ich S epar ation ). Random S epar ation (available when DPM C ollec tion and Edge S epar ation are enabled) allo ws the r andom selec tion of the lo cations a t which the newly spa wn par ticles ar e injec ted (due t o film separ ation) along the edge a t which the separ ation tak es plac e. Stripping Options (available when DPM C ollec tion and Particle S tripping are enabled) allo ws you t o set DPM par ticle stripping options (see Film S tripping in the Theor y Guide (p.1)). Critical S hear S tress is the cr itical value of the shear str ess on the fac e wher e liquid film e xists , which, when e xceeded , causes mass t o be tak en fr om the film. Diamet er C oefficien t is the v alue of used in Equa tion 22.20 in the Theor y Guide (p.1). Mass C oefficien t is the v alue of used in Equa tion 22.21 in the Theor y Guide (p.1). Splashing Options (available when DPM C ollec tion and Particle S plashing are enabled) allo ws you t o set DPM par ticle splashing options (see Film Sub-M odels in the Theor y Guide (p.1)). Splashed P articles is the numb er of splashed discr ete par ticles . Phase A ccretion Options (available when Phase A ccretion is enabled) allo ws you t o set sec ondar y phase accr etion options (see Secondar y Phase A ccretion in the Theor y Guide (p.1)). Phase C onc entration is the v alue of used in Equa tion 22.24 in the Theor y Guide (p.1). Phase Velocity is the v alue of used in Equa tion 22.24 in the Theor y Guide (p.1). Solve Wall F ilm allows you t o sk ip the w all film solution dur ing the gas phase solution, but k eep the v ariables and setup ac tive. Initializ e allows you t o initializ e the w all film v ariables and pr epar e the solv er for the solution pr ocedur e.The film c annot b e solv ed without first initializing the w all film mo del. Solution M etho d and C ontrol contains c ontrols f or temp oral or spa tial discr etiza tion as w ell as w all film thick ness f or the E uler ian Wall Film mo del. Discr etiza tion allows you t o set the t emp oral or spa tial discr etiza tion metho ds. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3382Task P age R eference GuideTime allows you t o sp ecify the t emp oral discr etiza tion metho ds. Available options include: First Or der Explicit ,First Or der Implicit , or Second Or der Implicit . Continuit y allows you t o sp ecify the spa tial discr etiza tion metho ds for continuit y. Available options include: First Or der U pwind , or Second Or der U pwind . Momen tum allows you t o sp ecify the spa tial discr etiza tion metho ds for momen tum. Available options include: First Or der U pwind , or Second Or der U pwind . Energy allows you t o sp ecify the spa tial discr etiza tion metho ds for momen tum. Available options include: First Or der U pwind , or Second Or der U pwind . Thick ness C ontrol allows you t o sp ecify Maximum Thick ness . Time M arching and Time S tep C ontrol allows you t o set the numb er of sub-st eps tha t the film mo del will tak e between time st eps fr om the main solv er. For e xample , if the flo w time st ep is 0.001 sec onds and the numb er of time st eps is set to 10 in the film mo del, the film mo del will tak e 10 time st eps of 0.0001 so tha t the film time and the flow time ma tch a t the end of the solution st ep. For implicit time st epping , the film mo del will tak e 5 additional sub it erations p er implicit st ep, stopping the sub-st ep when the film r esidual dr ops b elow the v alue set in the Sub-I teration S top option. Adaptiv e Time S tepping (steady-sta te flo w) enables the adaptiv e time st epping metho d to det ermine the film time st ep ( ) using the maximum C ourant numb er and the initial time st ep (see Steady Flow in the Theor y Guide (p.1)). Max. Cour ant Numb er is the maximum v alue of the C ourant numb er used t o comput e the film time st ep. Initial Time S tep is an initial v alue f or the time st ep used t o comput e the film time st ep. Time-S tep (steady-sta te flo w; default) is the user-sp ecified siz e of the time st ep, (see Steady Flow in the Theor y Guide (p.1)). Sub-T ime S teps (transien t flo w) is used in Equa tion 22.52 in the Theor y Guide (p.1). Sub-T ime Rep ort Interval (transien t flo w) sp ecifies the numb er of it erations b etween the w all film solution r eports. Sub-I terations (available when either First Or der Implicit or Second Or der Implicit are enabled f or Time under Discr etiza tion ) is the numb er of additional sub it erations p er implicit st ep. 3383Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Models Task P ageSub-I teration S top (available when either First Or der Implicit or Second Or der Implicit are enabled f or Time under Discr etiza tion ) is the p oint at which the sub it erations st op (when the film r esidual dr ops b elow this v alue). Sub-I ter Rep ort Interval (implicit time discr etiza tion c alcula tion) sp ecifies the numb er of sub-it erations b etween the w all film solution r eports. DPM C ontrol (available when DPM C ollec tion is enabled in the Model Options and S etup tab) allo ws you t o specify DPM-sp ecific discr etiza tion. Film S teps p er DPM st ep allows you t o set ho w of ten the DPM phase is c alcula ted f or the film. 47.4.54. Potential D ialo g Box The Potential dialo g box allo ws you t o set par amet ers r elated t o the elec tric potential field in y our model. See Using the E lectric Potential M odel (p.2351 ) for details . Controls Potential contains inputs r elated t o mo deling of the elec tric potential field . Potential E qua tion enables/disables the simula tion of the elec tric potential field in the mo del. Model Option allows you t o enable/disable the Include J oule H eating in E nergy Equa tion option. This option app ears only if the ener gy equa tion is enabled . 47.5. Materials Task P age The Materials task page allo ws you t o set pr operties f or an y fluid or solid (or mix ture, if applic able) materials in y our ANSY S Fluen t simula tion. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3384Task P age R eference GuideControls Materials contains a listing of a vailable fluid or solid (or mix ture, if applic able) ma terials. Create/Edit... displa ys the Create/Edit M aterials D ialog Box (p.3386 ) for the selec ted it em in the Materials list. Delet e remo ves the selec ted ma terial fr om the Materials list, For additional inf ormation, see the f ollowing sec tions: 47.5.1. Create/Edit M aterials D ialog Box 47.5.2. Fluen t Database M aterials D ialog Box 47.5.3. Open D atabase D ialog Box 3385Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Materials Task P age47.5.4. User-D efined D atabase M aterials D ialog Box 47.5.5. Copy Case M aterial D ialog Box 47.5.6. Material P roperties D ialog Box 47.5.7. Edit P roperty Metho ds D ialog Box 47.5.8. New M aterial N ame D ialog Box 47.5.9. Polynomial P rofile D ialog Box 47.5.10. Piecewise-Linear P rofile D ialog Box 47.5.11. Piecewise-P olynomial P rofile D ialog Box 47.5.12. Model Options D ialog Box 47.5.13. Compr essible Liquid D ialog Box 47.5.14. User-D efined F unctions D ialog Box 47.5.15. Suther land La w D ialog Box 47.5.16. Power La w D ialog Box 47.5.17. Non-N ewtonian P ower La w D ialog Box 47.5.18. Carreau M odel D ialog Box 47.5.19. Cross M odel D ialog Box 47.5.20. Herschel-B ulkley Dialog Box 47.5.21. Biaxial C onduc tivit y Dialog Box 47.5.22. Cylindr ical Or thotr opic C onduc tivit y Dialog Box 47.5.23. Orthotr opic C onduc tivit y Dialog Box 47.5.24. Anisotr opic C onduc tion - P rincipal C omp onen ts D ialog Box 47.5.25. Anisotr opic C onduc tivit y Dialog Box 47.5.26. Species D ialog Box 47.5.27. Reactions D ialog Box 47.5.28. Backward Reaction P aramet ers D ialog Box 47.5.29. Third-Body Efficienc y Dialog Box 47.5.30. Pressur e-Dependen t Reaction D ialog Box 47.5.31. Coverage-D ependen t Reaction D ialog Box 47.5.32. Reference Mass F ractions D ialog Box 47.5.33. Reaction M echanisms D ialog Box 47.5.34. Site Paramet ers D ialog Box 47.5.35. Mass D iffusion C oefficien ts D ialog Box 47.5.36. Thermal D iffusion C oefficien ts D ialog Box 47.5.37. UDS D iffusion C oefficien ts D ialog Box 47.5.38. WSGGM U ser S pecified D ialog Box 47.5.39. Gray-Band A bsor ption C oefficien t Dialog Box 47.5.40. Delta-E ddingt on Sc attering F unction D ialog Box 47.5.41. Gray-Band R efractive Inde x Dialog Box 47.5.42. Single R ate Model D ialog Box 47.5.43. Two Comp eting R ates M odel D ialog Box 47.5.44. CPD M odel D ialog Box 47.5.45. Kinetics/D iffusion-Limit ed C ombustion M odel D ialog Box 47.5.46. Intrinsic C ombustion M odel D ialog Box 47.5.47. Multiple Sur face Reactions D ialog Box 47.5.48. Edit M aterial D ialog Box 47.5.1. Create/Edit M aterials D ialo g Box The Create/Edit M aterials dialo g box is used t o cr eate and mo dify ma terials. Materials c an b e do wn- loaded fr om the global da tabase or defined lo cally. See Physical Properties (p.1079 ) for details ab out defining ma terial pr operties.Using the Create/Edit M aterials Dialog Box (p.1081 ) descr ibes ho w to use the dialo g box. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3386Task P age R eference GuideControls Name shows the name of the ma terial. If you edit this field , the new name will tak e eff ect when y ou click Change/C reate. Chemic al F ormula displa ys the chemic al formula f or the ma terial.You should gener ally not edit this field unless y ou ar e creating a ma terial fr om scr atch. Material Type is a dr op-do wn list c ontaining all of the a vailable ma terial types. By default ,fluid and solid will b e the only choic es. If you ar e mo deling sp ecies tr ansp ort/combustion, mix ture will also b e available . For problems in which y ou ha ve defined discr ete-phase injec tions ,iner t-par ticle ,droplet-par ticle , and/or combusting-par ticle will also app ear. Fluen t Fluid M aterials allows you t o cho ose the fluid ma terial for which y ou w ant to mo dify pr operties.This option is a vailable when fluid is selec ted in the Material Type drop-do wn list. Fluen t Solid M aterials allows you t o cho ose the solid ma terial for which y ou w ant to mo dify pr operties.This option is a vailable when solid is selec ted in the Material Type drop-do wn list. Fluen t Mixture M aterials allows you t o cho ose the mix ture ma terial for which y ou w ant to mo dify pr operties.This option is a vailable when mix ture is selec ted in the Material Type drop-do wn list. Fluen t Droplet P article M aterials allows you t o cho ose the dr oplet-par ticle f or which y ou w ant to mo dify pr operties.This option is a vailable when droplet-par ticle is selec ted in the Material Type drop-do wn list. Order M aterials b y allows you t o or der the ma terials in the Materials list alphab etically b y Name or alphab etically b y Chemic al F ormula . 3387Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Materials Task P ageFluen t Database ... opens the Fluen t Database M aterials D ialog Box (p.3396 ), from wher e you c an c opy ma terials fr om the global da tabase in to the cur rent solv er. User-D efined D atabase ... opens the Open D atabase D ialog Box (p.3397 ), wher e you c an sp ecify the user-defined da tabase t o be used . Properties contains input fields f or the ma terial pr operties tha t are requir ed f or the ac tive ph ysical mo dels . Densit y sets the ma terial densit y.You ma y set a c onstan t value , or selec t one of the other metho ds fr om the drop-do wn list ab ove the r eal numb er field . See Densit y (p.1099 ) for instr uctions on setting densit y. Cp (S pecific H eat) sets the c onstan t-pressur e sp ecific hea t of the ma terial.You ma y set a c onstan t value , or selec t one of the other metho ds fr om the dr op-do wn list ab ove the r eal numb er field . See Specific H eat Capa- city (p.1136 ) for instr uctions on setting sp ecific hea t. Thermal C onduc tivit y sets the ther mal c onduc tivit y of the ma terial.You ma y set a c onstan t value , or selec t one of the other metho ds fr om the dr op-do wn list ab ove the r eal numb er field . See Thermal C onduc tivit y (p.1117 ) for instr uctions on setting ther mal c onduc tivit y. Visc osit y sets the visc osity of the ma terial.You ma y set a c onstan t value , or selec t one of the other metho ds from the dr op-do wn list ab ove the r eal numb er field . See Viscosity (p.1107 ) for instr uctions on setting viscosity. Molecular Weigh t sets the molecular w eigh t of the ma terial. It is used t o der ive the gas c onstan t of the ma terial. Standar d State Enthalp y specifies the f ormation en thalp y of a fluid ma terial for a r eacting flo w. See Standar d State En thal- pies (p.1150 ) for details . Standar d State Entropy specifies the standar d sta te en tropy of a fluid ma terial for a r eacting flo w.This input is used only if the fluid ma terial is in volved in a r eversible r eaction. See Standar d State En tropies (p.1151 ) for details . Referenc e Temp erature specifies the r eference temp erature for the Heat of F ormation . L-J C haracteristic L ength specifies the k inetic theor y par amet er for a fluid ma terial. See Kinetic Theor y Paramet ers (p.1151 ) for details . L-J E nergy Paramet er specifies the k inetic theor y par amet er for a fluid ma terial. See Kinetic Theor y Paramet ers (p.1151 ) for details . Absor ption C oefficien t specifies the absor ption c oefficien t for radia tion hea t transf er. See Radia tion P roperties (p.1137 ) for details . If you cho ose the wsggm-user-sp ecified option fr om the dr op-do wn list ne xt to Absor ption Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3388Task P age R eference GuideCoefficien t, the WSGGM U ser S pecified D ialog Box (p.3434 ) will op en. If you cho ose the user-defined- wsggm option fr om the dr op-do wn list ne xt to Absor ption C oefficien t, the User-D efined F unctions Dialog Box (p.3406 ) will op en. Scattering C oefficien t specifies the sc attering c oefficien t for radia tion hea t transf er (only f or the P-1, Rosseland , DO, or MC r adia tion mo dels). See Radia tion P roperties (p.1137 ) for details . Scattering P hase F unc tion specifies an isotr opic (by default) or linear-anisotr opic scattering func tion. If you ar e using the DO or MC mo dels ,delta-eddingt on and user-defined scattering func tions ar e also a vailable . See Radia tion Properties (p.1137 ) for details . If you cho ose delta-eddingt on, the Delta-E ddingt on Sc attering F unction Dialog Box (p.3435 ) will op en. Refr active Inde x specifies the r efractive inde x for the ma terial. It is used only when semi-tr anspar ent media ar e mo deled with the DO or MC r adia tion mo dels . Mixture Species specifies the names of the sp ecies tha t mak e up a mix ture ma terial.To check or mo dify these names , click the Edit... butt on t o op en the Species D ialog Box (p.3417 ).This pr operty app ears only f or mix ture materials. Reac tion displa ys the r eaction mechanism b eing used when y ou ar e mo deling finit e-rate reactions .finit e-rate app ears if LaminarF init e-Rate or Eddy-D issipa tion C onc ept is selec ted in the Species M odel D ialog Box (p.3294 ),edd y-dissipa tion app ears if Eddy-D issipa tion is selec ted, and finit e-rate/edd y-dissip- ation app ears if Finit e-Rate/Eddy-D issipa tion is selec ted. Click Edit... to op en the Reactions D ialog Box (p.3419 ). Mechanism allows you t o enable diff erent reactions selec tively in diff erent geometr ical zones . Click the Edit butt on to op en the Reaction M echanisms D ialog Box (p.3428 ). See Defining Z one-B ased R eaction M echan- isms (p.1642 ) for details . Mass D iffusivit y contains a dr op-do wn list of a vailable metho ds for sp ecifying the diffusion c oefficien ts for the sp ecies in a mix ture ma terial. If you selec t constan t-dilut e-appx , you will en ter a c onstan t value in the field below. If you selec t dilut e-appr ox or multic omp onen t, the Mass D iffusion C oefficien ts D ialog Box (p.3431 ) will op en, and y ou c an sp ecify the c oefficien ts ther e. If you selec t kinetic-theor y, you will need t o sp ecify the k inetic theor y par amet ers f or the individual fluid ma terials (sp ecies) tha t mak e up the mix ture. See Mass D iffusion C oefficien ts (p.1141 ) for details ab out sp ecifying mass diffusivit y. Thermal D iffusion C oefficien t contains a dr op-do wn list of a vailable metho ds for sp ecifying the ther mal diffusion c oefficien ts for the sp ecies in a mix ture ma terial. If you selec t kinetic-theor y, you will need t o sp ecify the k inetic theor y ma terials (sp ecies) tha t mak e up the mix ture. If you selec t specified , the Thermal D iffusion Coefficien ts D ialog Box (p.3432 ) will op en, and y ou c an sp ecify the c oefficien ts ther e. See Thermal D if- fusion C oefficien t Inputs (p.1145 ) for details ab out sp ecifying ther mal diffusion c oefficien ts. Densit y of U nbur nt Reac tants sets the densit y ( in Equa tion 9.69 in the Theor y Guide ) of the unbur nt produc ts. 3389Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Materials Task P ageTemp erature of U nbur nt Reac tants sets the t emp erature ( in Equa tion 9.69 in the Theor y Guide ) of the unbur nt produc ts. Adiaba tic Temp erature of Bur nt Produc ts (only f or adiaba tic pr emix ed c ombustion mo dels) sp ecifies the v alue of the bur nt produc ts under adiaba tic c onditions , in Equa tion 9.66 in the Theor y Guide . Unbur nt Thermal D iffusivit y specifies the ther mal diffusivit y ( in Equa tion 9.8 in the Theor y Guide ) for use with the pr emix ed combustion mo del. See Modeling P remix ed C ombustion (p.1749 ) for details . Laminar F lame S peed specifies the v alue of in Equa tion 9.8 in the Theor y Guide . Laminar F lame Thick ness specifies the thick ness of the flame f or which y ou ha ve a choic e of constan t,user-defined , or diffus- ivity-over-flame-sp eed . Critical R ate of S train specifies the v alue of in Equa tion 9.17 in the Theor y Guide . Heat of C ombustion (only f or non-adiaba tic pr emix ed c ombustion mo dels) sp ecifies the v alue of in Equa tion 9.68 in the Theor y Guide . Unbur nt Fuel M ass F raction (only f or non-adiaba tic pr emix ed c ombustion mo dels) sp ecifies the v alue of in Equa tion 9.68 in the Theor y Guide . Thermal E xpansion C oefficien t specifies the ther mal e xpansion c oefficien t ( in Equa tion 13.3 (p.1477 )) for use with the B oussinesq appr oxima tion. See Steps in S olving B uoyancy-Driven F low Problems (p.1477 ) for details . Droplet S urface Tension specifies the v alue of the dr oplet sur face tension ( in Equa tion 16.349 in the Theor y Guide ). Latent Heat is the la tent hea t of v aporization, , requir ed f or phase change fr om an e vaporating liquid dr oplet or for the e volution of v olatiles fr om a c ombusting par ticle . See Setting M aterial P roperties f or the Discrete Phase (p.2008 ) for details . Latent Heat at NBP is the la tent hea t of v aporization a t the nor mal b oiling p oint, available f or dr oplet-par ticles . See Using the C ubic E qua tion of S tate Models with the Lagr angian D ispersed P hase M odels (p.1171 ) for details . Normal B oiling P oint (NBP) is giv en b y Equa tion 8.117 (p.1172 ). See Using the C ubic E qua tion of S tate Models with the Lagr angian Dispersed P hase M odels (p.1171 ) for details . Thermophor etic C oefficien t specifies the ther mophor etic c oefficien t ( in Equa tion 16.11 in the Theor y Guide ), and app ears when the ther mophor etic f orce is included in the discr ete phase c alcula tion. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3390Task P age R eference GuideVaporization Temp erature is the t emp erature, , at which the c alcula tion of v aporization fr om a liquid dr oplet or de volatiliz- ation fr om a c ombusting par ticle is initia ted b y ANSY S Fluen t. See Setting M aterial P roperties f or the Discrete Phase (p.2008 ) for details . Boiling P oint is the t emp erature, , at which the c alcula tion of the b oiling r ate equa tion is initia ted b y ANSY S Fluen t. See Setting M aterial P roperties f or the D iscrete Phase (p.2008 ) for details . Vapor-P article-E quilibr ium is the selec ted appr oach f or the c alcula tion of the v apor concentration of the c omp onen ts at the surface.This c an b e Raoult ’s law (Equa tion 16.198 in the Theor y Guide ), the P eng-R obinson r eal gas model ( Equa tion 16.206 in the Theor y Guide ), or a user-defined func tion tha t provides this v alue . Volatile C omp onen t Fraction ( ) is the fr action of a dr oplet par ticle tha t ma y vaporize via La ws 2 and/or 3 ( Droplet Vaporization (Law 2) in the Theor y Guide ). For combusting par ticles , it is the fr action of v olatiles tha t ma y be evolved via La w 4 ( Devolatiliza tion (La w 4) in the Theor y Guide ). See Setting M aterial P roperties f or the D iscrete Phase (p.2008 ) for details . Binar y Diffusivit y is the mass diffusion c oefficien t, , used in the v aporization la w, Law 2. This input is also used t o define the mass diffusion of the o xidizing sp ecies t o the sur face of a c ombusting par ticle , . See Setting M aterial P roperties f or the D iscrete Phase (p.2008 ) for details . Diffusivit y Ref erenc e Pressur e is the r eference pr essur e for the pr essur e dep enden t binar y diffusivit y in Equa tion 16.113 in the Fluent Theor y Guide . Saturation Vapor P ressur e is the sa turated v apor pr essur e, , defined as a func tion of t emp erature, which is used in the v apor- ization la w, Law 2. See Setting M aterial P roperties f or the D iscrete Phase (p.2008 ) for details . Heat of P yrolysis is the hea t of the instan taneous p yrolysis r eaction, , tha t the e vaporating/b oiling sp ecies ma y under go when r eleased t o the c ontinuous phase .The hea t of p yrolysis should b e en tered as a p ositiv e numb er for e xother mic r eaction and as a nega tive numb er for endother mic r eaction. The default value of z ero implies tha t the hea t of p yrolysis is not c onsider ed. See Setting M aterial P roperties f or the D iscrete Phase (p.2008 ) for details . Comp osition A veraging C oefficien t is the c oefficien t in Equa tion 16.208 in the Fluent Theor y Guide .To assume bulk gas c omp osition for the ph ysical pr operties in the par ticle v aporization and hea ting r ates equa tions , selec t none from the Comp osition A veraging C oefficien t drop-do wn in the Create/Edit M aterials dialo g box, under Properties .To enable pr operty averaging , selec t constant and en ter a v alue b etween 0 and 1 f or 3391Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Materials Task P agethe Comp osition A veraging C oefficien t. = 1 c orresponds t o bulk gas mix ture. For = 0, the comp osition r everts to the par ticle sur face comp osition. Imp ortant When y ou define the Comp osition A veraging C oefficien t with a constant value other than 1, you must also sp ecify Specific H eat,Visc osit y and Thermal C onduc t- ivity for the e vaporating sp ecies (in the Create/Edit M aterials dialo g box, under Properties , for the c orresponding fluid ma terial of the c ontinuous phase mix ture). The default and r ecommended v alue f or the a veraging c oefficien t is 1/3. However, to impr ove the simula tion r esults , you must pr ovide accur ate temp erature-dep enden t da ta for the v apor material. Temp erature Averaging C oefficien t is the c oefficien t in Equa tion 16.207 in the Fluent Theor y Guide .To assume bulk gas t emp erature for the ph ysical pr operties in the par ticle v aporization and hea ting r ates equa tions , selec t none from the Temp erature Averaging C oefficien t drop-do wn in the Create/Edit M aterials dialo g box, under Properties .To enable pr operty averaging , selec t constant and en ter a v alue b etween 0 and 1 f or the Temp erature Averaging C oefficien t. = 1 c orresponds t o bulk gas c onditions . For = 0, the temp erature reverts to the par ticle sur face temp erature. Imp ortant When y ou define the Temp erature Averaging C oefficien t with a constant value other than 1, you must also sp ecify Specific H eat,Visc osit y and Thermal C onduc t- ivity for the e vaporating sp ecies (in the Create/Edit M aterials dialo g box, under Properties , for the c orresponding fluid ma terial of the c ontinuous phase mix ture). The default and r ecommended v alue f or the a veraging c oefficien t is 1/3. However, to impr ove the simula tion r esults , you must pr ovide accur ate temp erature-dep enden t da ta for the e vapor- ating v apor ma terial. Vaporization/B oiling M odel defines which v aporization/b oiling mo del is used f or pur e dr oplets (La w 2) and f or multic omp onen t droplets (La w 7). If you w ant to use the default diffusion-c ontrolled mo del, retain the selec tion of diffusion- controlled from the dr op-do wn list t o the r ight of Vaporization/B oiling M odel.This will apply Equa tion 16.102 in the Theor y Guide . To use the c onvection/diffusion-c ontrolled mo del f or v aporization selec t convection/diffusion- controlled from the dr op-do wn list. Equa tion 16.107 in the Theor y Guide will b e applied f or the c alcula tion of the v aporization r ate, and Equa tion 16.119 in the Theor y Guide will b e applied in the par ticle hea t transf er calcula tions This mo del is r ecommended when e vaporation r ates are high. For slo wly e vaporating dr oplets b oth mo dels ar e expected t o giv e similar r esults . You c an selec t options f or the v aporization/b oiling mo del in the Model Options D ialog Box (p.3405 ) tha t op ens when y ou click Edit... next to Vaporization/B oiling M odel. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3392Task P age R eference GuideDegrees of F reedom specifies the k inetic theor y par amet er , which is the numb er of no des of ener gy storage.This par a- met er is r equir ed only if y ou ar e defining sp ecific hea t via k inetic theor y. See Kinetic Theor y Paramet- ers (p.1151 ) for details . Particle E missivit y is the emissivit y of par ticles in y our mo del, , used t o comput e radia tion hea t transf er to the par ticles when the P-1 or DO r adia tion mo del is ac tive and par ticle r adia tion in teraction is enabled in the Discrete Phase M odel D ialog Box (p.3360 ). See Setting M aterial P roperties f or the D iscrete Phase (p.2008 ) for details . Particle Sc attering F actor is the sc attering fac tor, , due t o par ticles in the P-1 or DO r adia tion mo del. Note tha t this pr operty will app ear only if par ticle r adia tion in teraction is enabled in the Discrete Phase M odel D ialog Box (p.3360 ). See Setting M aterial P roperties f or the D iscrete Phase (p.2008 ) for details . Swelling C oefficien t is the c oefficien t, , which go verns the sw elling of the c oal par ticle dur ing the de volatiliza tion la w, Law 4. A sw elling c oefficien t of unit y (the default) implies tha t the c oal par ticle sta ys at constan t dia- met er dur ing the de volatiliza tion pr ocess. See Setting M aterial P roperties f or the D iscrete Phase (p.2008 ) for details . Bur nout S toichiometr ic R atio is the st oichiometr ic requir emen t, , for the bur nout r eaction, in t erms of mass of o xidan t per mass of char in the par ticle . See Setting M aterial P roperties f or the D iscrete Phase (p.2008 ) for details . Combustible F raction is the mass fr action of char , , in the c oal par ticle (the fr action of the initial c ombusting par ticle that will r eact in the sur face reaction) La w 5. See Setting M aterial P roperties f or the D iscrete Phase (p.2008 ) for details . Reac t. Heat Fraction A bsorb ed b y Solid is the par amet er , which c ontrols the distr ibution of the hea t of r eaction b etween the par ticle and the c ontinuous phase .The default v alue of z ero implies tha t the en tire hea t of r eaction is r eleased t o the c ontinuous phase . See Setting M aterial P roperties f or the D iscrete Phase (p.2008 ) for details . Heat of Reac tion f or Bur nout is the hea t released b y the sur face char c ombustion r eaction, Law 5. This par amet er is sp ecified in terms of hea t release (f or e xample , Joules) p er unit mass of char c onsumed in the sur face reaction. See Setting M aterial P roperties f or the D iscrete Phase (p.2008 ) for details . Devolatiliza tion M odel defines which v ersion of the de volatiliza tion mo del, Law 4, is b eing used . If you w ant to use the default constan t rate de volatiliza tion mo del, retain the selec tion of constan t in the dr op-do wn list t o the right of Devolatiliza tion M odel and en ter the r ate constan t in the field b elow the list. Selec t single-r ate,two-comp eting-r ates, or cpd-mo del in the dr op-do wn list t o cho ose one of the optional de volatiliza tion mo dels (the single k inetic r ate mo del, two kinetic r ates mo del, or CPD mo del, as descr ibed in Devolatiliza tion (La w 4) in the Theor y Guide ). When the single k inetic r ate mo del ( single-r ate) is selec ted, the Single R ate M odel D ialog Box (p.3436 ) will app ear; when the t wo comp eting r ates mo del ( two-comp eting-r ates) is selec ted, the Two Comp eting R ates M odel D ialog Box (p.3437 ) will app ear; and when the CPD mo del (cpd-mo del) is selec ted, the CPD M odel D ialog Box (p.3438 ) will app ear. 3393Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Materials Task P ageSee Setting M aterial P roperties f or the D iscrete Phase (p.2008 ) for details . Combustion M odel defines which v ersion of the sur face char c ombustion la w (La w 5) is b eing used . If you w ant to use the default diffusion-limit ed r ate mo del, retain the selec tion of diffusion-limit ed in the dr op-do wn list. No additional inputs ar e nec essar y, because the binar y diffusivit y defined ab ove will b e used in Equa tion 16.168 in the Theor y Guide . To use the k inetics/diffusion-limit ed r ate mo del f or the sur face combustion mo del, selec t kin- etics/diffusion-limit ed in the dr op-do wn list and en ter the par amet ers in the r esulting Kinet- ics/D iffusion-Limit ed C ombustion M odel D ialog Box (p.3439 ). To use the in trinsic mo del f or the sur face combustion mo del, selec t intrinsic-mo del in the drop-do wn list and en ter the par amet ers in the r esulting Intrinsic C ombustion M odel D ialog Box (p.3440 ). To use the multiple sur face reactions mo del, selec t multiple-sur face-reac tions in the dr op- down list. See Setting M aterial P roperties f or the D iscrete Phase (p.2008 ) for details . Pure Solvent Melting H eat specifies the la tent hea t for the melting and solidific ation mo del ( in Equa tion 20.3 in the Theor y Guide ). Solidus Temp erature specifies the solidus t emp erature for the melting and solidific ation mo del ( in Equa tion 20.3 in the Theor y Guide ). If you ar e solving f or sp ecies tr ansp ort, the solidus t emp erature is in Equa tion 20.8 , and y ou sp ecify the metho d by which it is c alcula ted: either acc ording t o the mixing- law (which is based on the par amet ers of the solut es) or a user-defined func tion. Liquidus Temp erature specifies the liquidus t emp erature for the melting and solidific ation mo del ( in Equa tion 20.3 in the Theor y Guide ). If you ar e solving f or sp ecies tr ansp ort, the liquidus t emp erature is in Equa tion 20.9 , and y ou sp ecify the metho d by which it is c alcula ted: either acc ording t o the mixing- law (which is based on the par amet ers of the solut es) or a user-defined func tion. Pure Solvent Melting Temp erature specifies the melting t emp erature of pur e solv ent ( in Equa tion 20.8 and Equa tion 20.9 in the Theor y Guide ) for the melting and solidific ation mo del when sp ecies tr ansp ort has also b een enabled . The solv ent is the last sp ecies list ed under of the mix ture ma terial. Eutectic Temp erature is the lo west allo y melting t emp erature, which dep ends on the r elative pr oportions of the mix ture comp osition of the E utectic sp ecies mass fr actions . Slope of Liquidus Line specifies the slop e of the liquidus sur face with r espect to the c oncentration of the solut e ( in Equa tion 20.8 and Equa tion 20.9 in the Theor y Guide ). It is not nec essar y to sp ecify this v alue f or the solv ent. Note tha t this option is a vailable only f or the melting and solidific ation mo del when sp ecies transp ort has also b een enabled . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3394Task P age R eference GuidePartition C oefficien t specifies the par tition c oefficien t with r espect to the c oncentration of the solut e fluid ( in Equa- tion 20.8 and Equa tion 20.9 in the Theor y Guide ). It is not nec essar y to sp ecify this v alue f or the solv ent. Note tha t this option is a vailable only f or the melting and solidific ation mo del when sp ecies tr ansp ort has also b een enabled . Eutectic M ass F raction is the mass fr action of a solut e in an allo y at which the melting t emp erature of the allo y is the lo west possible v alue ( in Equa tion 20.10 in the Theor y Guide ). It is not nec essar y to sp ecify this v alue for the solv ent. Note tha t this option is a vailable only f or the melting and solidific ation mo del when species tr ansp ort has also b een enabled . Solutal E xpansion C oefficien t allows you t o sp ecify the c oefficien t in Equa tion 20.24 in the Theor y Guide for all the sp ecies e xcept the last one in the mix ture. Note tha t this option is a vailable only f or the melting and solidific ation model when the Include S olutal Buo yanc y option is enabled . Diffusion in S olid specifies the r ate of diffusion in the solid . Note tha t this option is a vailable only f or the melting and solidific ation mo del when the L ever rule is selec ted and the sp ecies tr ansp ort is enabled . UDS D iffusivit y specifies the diffusion c oefficien t for a user-defined sc alar.This ma terial pr operty is a vailable in the Create/Edit M aterials D ialog Box (p.3386 ) when y ou sp ecify one or mor e user-defined sc alars in the User-D efined Sc alars D ialog Box (p.3953 ). If you selec t defined-p er-uds , you will need t o sp ecify the diffusion c oefficien t for each user-defined sc alar tr ansp ort equa tion in the UDS D iffusion C oefficien ts Dialog Box (p.3433 ). Youngs M odulus specifies the Young's mo dulus .This ma terial pr operty is only a vailable f or solid ma terials when y ou have selec ted a mo del in the Structural M odel D ialog Box (p.3378 ). Poisson R atio specifies the P oisson's r atio.This ma terial pr operty is only a vailable f or solid ma terials when y ou ha ve selec ted a mo del in the Structural M odel D ialog Box (p.3378 ). Electrical C onduc tivit y sets the ma terial elec trical conduc tivit y.You ma y set a c onstan t value , or selec t one of the other metho ds fr om the dr op-do wn list ab ove the r eal numb er field .This ma terial pr operty only b ecomes available if the elec tric potential mo del is enabled . Charge N umb er specifies the char ge numb er for a fluid ma terial for a flo w in volving elec trochemic al reactions .The default setting of 0 means tha t the fluid sp ecies is neutr al.This ma terial pr operty only b ecomes available if the elec tric potential mo del is enabled . When y ou ar e viewing the da tabase , additional pr operties ma y be displa yed. However, after y ou copy the ma terial t o the lo cal ar ea, only the pr operties with r elevance to the cur rent problem will be displa yed. Change/C reate changes the pr operties of a lo cally st ored ma terial or cr eates a new one in the lo cal ar ea. If no ma terial with the sp ecified Name exists lo cally, ANSY S Fluen t will cr eate it. If you ha ve mo dified the ma terial without changing its name , ANSY S Fluen t will simply up date the ma terial with y our mo dific ations . If you 3395Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Materials Task P agehave assigned a new name t o the ma terial and a ma terial with this name alr eady exists lo cally, an er ror will b e indic ated; you must then sp ecify a diff erent name or delet e the e xisting ma terial with tha t name before trying t o sa ve the new ma terial. Delet e delet es the cur rently selec ted ma terial fr om the lo cal ma terials list. It has no eff ect on the global da tabase . 47.5.2. Fluen t Database M aterials D ialo g Box The Fluen t Database M aterials dialo g box is op ened b y click ing the Fluen t Database ... butt on in the Create/Edit M aterials D ialog Box (p.3386 ). In this dialo g box you c an view the global (sit e-wide) material pr operties da tabase and c opy ma terials list in the solv er. See Copying M aterials fr om the ANSY S Fluen t Database (p.1084 ) for details . Controls Fluen t Fluid M aterials contains a list of all ma terials of the selec ted Material Type tha t are defined in the da tabase .The name of this list will change dep ending on the selec ted ma terial type (for e xample ,fluid ,solid , and so on). You can selec t one or mor e of these ma terials t o be copied t o the solv er. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3396Task P age R eference GuideMaterial Type is a dr op-do wn list c ontaining all of the a vailable ma terial types. By default ,fluid and solid will b e the only choic es. If you ar e mo deling sp ecies tr ansp ort/combustion, mix ture will also b e available . For problems in which y ou ha ve defined discr ete-phase injec tions ,iner t-par ticle ,droplet-par ticle , and/or combusting-par ticle will also app ear. Order M aterials b y allows you t o or der the ma terials in the Materials list alphab etically b y Name or alphab etically b y Chemic al F ormula . Copy M aterials fr om C ase... opens the Copy Case M aterial D ialog Box (p.3399 ). Delet e delet es the selec ted ma terials fr om the da tabase . Properties contains fields f or the ma terial pr operties tha t are defined f or the selec ted ma terial.These fields ar e for informational pur poses only ; the y cannot b e edit ed. When y ou ar e viewing the da tabase , not all pr operties displa yed ar e relevant to your ANSY S Flu- ent solution. After y ou c opy the ma terial, only pr operties with r elevance to the cur rent ph ysical models will b e displa yed. Copy copies the cur rent ma terial fr om the global da tabase t o the lo cal ma terials list in the solv er. 47.5.3. Op en D atabase D ialo g Box The Open D atabase dialo g box is op ened b y click ing the User-D efined D atabase butt on in the Cre- ate/Edit M aterials D ialog Box (p.3386 ). Controls Browse... opens The S elec t File D ialog Box (p.569) wher e you c an selec t the user-defined da tabase t o be used in the cur rent solv er session. Database N ame allows you t o en ter the pa th and name of a new da tabase . If you selec t an e xisting da tabase , this field displa ys the pa th and name of the selec ted da tabase . 3397Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Materials Task P age47.5.4. User-D efined D atabase M aterials D ialo g Box The User-D efined D atabase M aterials dialo g box is op ened b y click ing OK in the Open D atabase Dialog Box (p.3397 ). In this dialo g box you c an view the user-defined ma terial pr operties da tabase and copy ma terials list in the solv er. See Viewing M aterials in a U ser-D efined D atabase (p.1089 ) for details . Controls User-D efined M aterials contains a list of all ma terials of the selec ted Material Type tha t are defined in the da tabase .The name of this list will change dep ending on the selec ted ma terial type (for e xample ,User-D efined F luid M ater- ials,User-D efined S olid M aterials, and so on). You c an selec t one or mor e of these ma terials t o copy to your lo cal list or edit their pr operties. Material Type is a dr op-do wn list c ontaining all of the a vailable ma terial types. Order M aterials B y allows you t o or der the ma terials in the User-D efined M aterials list alphab etically b y Name or alphab et- ically b y Chemic al F ormula . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3398Task P age R eference GuideCopy M aterials fr om C ase... opens the Copy Case M aterial D ialog Box (p.3399 ). Delet e delet es the selec ted ma terials fr om the da tabase . Properties lists the pr operties and v alues of the selec ted ma terial. New... opens a blank Material P roperties D ialog Box (p.3399 ) wher e you c an define a new ma terial. Edit... opens the Material P roperties D ialog Box (p.3399 ) displa ying the pr operties of the selec ted ma terial. Save saves the inf ormation t o the selec ted da tabase . Copy copies the selec ted ma terial to your lo cal ma terial list. If the ma terial alr eady exists the New M aterial N ame Dialog Box (p.3401 ) opens 47.5.5. Copy Case M aterial D ialo g Box This dialo g box is op ened b y click ing the Copy M aterials fr om C ase... butt on in the User-D efined Database M aterials D ialog Box (p.3398 ). Controls Case M aterials lists all the ma terials pr esen t in y our lo cal ma terials list. Copy copies the selec ted ma terials t o the user-defined da tabase . 47.5.6. Material P roperties D ialo g Box This dialo g box is op ened b y click ing New... butt on in the User-D efined D atabase M aterials D ialog Box (p.3398 ). See Creating a N ew M aterials D atabase and M aterials (p.1092 ) for details . 3399Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Materials Task P ageControls Name specifies the name of the ma terial tha t you ar e creating . Formula (optional) sp ecifies the chemic al formula of the ma terial tha t you ar e creating . Types allows you t o selec t ma terial type from fluid , solid , inter-par ticle , droplet-par ticle , combusting-par ticle , and mix ture ma terials. Available P roperties lists pr operties applic able t o the selec ted ma terial type. Material P roperties lists pr operties tha t you ha ve selec ted fr om Available P roperties list. Edit... opens Edit P roperty Metho ds D ialog Box (p.3400 ) wher e you c an edit the par amet ers tha t define a pr operty. 47.5.7. Edit P roperty M etho ds D ialo g Box This dialo g box is op ened b y click ing Edit... butt on in the Material P roperties D ialog Box (p.3399 ). See Creating a N ew M aterials D atabase and M aterials (p.1092 ) for details . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3400Task P age R eference GuideControls Property Name specifies the name of the pr operty tha t you w ant to edit. Available P roperties specifies the metho ds tha t can b e used t o define the selec ted pr operty. Material P roperties lists pr operties tha t you ha ve selec ted fr om Available P roperties list. Edit P roperties allows you t o selec t the pr operty tha t you w ant to edit. 47.5.8. New M aterial N ame D ialo g Box This dialo g box is op ened b y click ing the Copy butt on in the User-D efined D atabase M aterials D ialog Box (p.3398 ) when a ma terial is alr eady defined with the same name in the Create/Edit M aterials D ialog Box (p.3386 ). 3401Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Materials Task P ageControls New N ame allows you t o en ter the new name f or the ma terial y ou need t o copy. New Formula allows you t o en ter the new f ormula f or the ma terial y ou need t o copy. 47.5.9. Polynomial P rofile D ialo g Box The Polynomial P rofile dialo g box allo ws you t o define a ph ysical pr operty as a p olynomial func tion of temp erature.This dialo g box will op en when y ou selec t polynomial in the dr op-do wn list ne xt to a ph ysical pr operty in the Create/Edit M aterials D ialog Box (p.3386 ). See Inputs f or P olynomial F unc- tions (p.1095 ) for details ab out the it ems b elow. Controls Define shows the pr operty tha t is b eing defined as a func tion of t emp erature. In Terms of shows the indep enden t variable ( Temp erature).The pr operty sho wn in Define will b e defined as a polynomial func tion of t emp erature. Coefficien ts is an in teger numb er en try tha t indic ates the numb er of c oefficien ts to be defined .You c an define up t o 8 coefficien ts. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3402Task P age R eference GuideCoefficien ts contains r eal numb er en tries f or the numb er of c oefficien ts set in the Coefficien ts integer numb er entry ab ove.The numb er of en tries tha t are editable will b e the same as the numb er of c oefficien ts you request ed. 47.5.10. Piecewise-Linear P rofile D ialo g Box The Piecewise-Linear P rofile dialo g box allo ws you t o define a ph ysical pr operty as a piec ewise-linear func tion of t emp erature.This dialo g box will op en when y ou selec t piec ewise-linear in the dr op-do wn list ne xt to a ph ysical pr operty in the Create/Edit M aterials D ialog Box (p.3386 ). See Inputs f or P iecewise- Linear F unctions (p.1096 ) for details ab out the it ems b elow. Controls Define shows the pr operty tha t is b eing defined as a func tion of t emp erature. In Terms of shows the indep enden t variable ( Temp erature).The pr operty sho wn in Define will b e defined as a piec ewise-linear func tion of t emp erature. Points indic ates the numb er of da ta pairs tha t will define the piec ewise distr ibution. You c an define up t o 50 pairs . Data P oints contains en tries f or defining the da ta pairs . Point indic ates the p oint for which the da ta pair ( Temp erature,Value ) is b eing defined . Temp erature is the indep enden t variable . Value is the dep enden t variable (the pr operty). In the e xample dialo g box ab ove,Visc osit y is the v ariable being defined , as sho wn in the Define field . 3403Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Materials Task P age47.5.11. Piecewise-P olynomial P rofile D ialo g Box The Piecewise-P olynomial P rofile dialo g box allo ws you t o define a ph ysical pr operty as a piec ewise- polynomial func tion of t emp erature.This dialo g box will op en when y ou selec t piec ewise-p olynomial in the dr op-do wn list ne xt to a ph ysical pr operty in the Create/Edit M aterials D ialog Box (p.3386 ). See Inputs f or P iecewise-P olynomial F unctions (p.1098 ) for details ab out the it ems b elow. Controls Define shows the pr operty tha t is b eing defined as a func tion of t emp erature. In Terms of shows the indep enden t variable ( Temp erature).The pr operty sho wn in Define will b e defined as a polynomial func tion of t emp erature. Ranges sets the numb er of t emp erature ranges f or which y ou will define p olynomial func tions .You c an define up t o 3 r anges . Range indic ates the t emp erature range f or which y ou ar e defining the p olynomial func tion. Minimum, Maximum set the minimum and maximum t emp eratures for the sp ecified Range . Coefficien ts is an in teger numb er en try tha t indic ates the numb er of c oefficien ts to be defined f or the sp ecified Range . You c an define up t o 8 c oefficien ts. Coefficien ts contains r eal numb er en tries f or the numb er of c oefficien ts set in the Coefficien ts integer numb er entry ab ove.The numb er of en tries tha t are editable will b e the same as the numb er of c oefficien ts you request ed f or the sp ecified Range . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3404Task P age R eference Guide47.5.12. Model Options D ialo g Box The Model Options dialo g box allo ws you t o selec t boiling mo del options and t o enable the c alcula tion of the S palding hea t numb er for the c onvection/diffusion v aporization mo del. This dialo g box op ens when y ou click Edit... next to Vaporization M odel in the Create/Edit M aterials D ialog Box (p.3386 ). Convection/D iffusion Vaporization M odel allows you t o enable Variable L ewis N umb er F ormula tion if you w ant to comput e the S palding hea t numb er fr om Equa tion 16.118 in the Fluent Theor y Guide .This gr oup b ox is a vailable only when y ou selec t convection/diffusion-c ontrolled for Vaporization/B oiling M odel. Boiling M odel is wher e you c an selec t the Use the S pecific H eat of the E vaporating S pecies in B oiling L aw option. This option sets the hea t capacit y of the gas ( in Equa tion 16.123 in the Fluent Theor y Guide ) to the specific hea t of the e vaporating sp ecies selec ted in the Set Injec tion P roperties dialo g box. For the convection/diffusion c ontrolled mo del with the Variable L ewis N umb er F ormula tion , this option is selec ted b y default. This ensur es c onsist ency with the c onvection/diffusion c ontrolled mo del e xpression for in Equa tion 16.117 in the Fluent Theor y Guide . For mor e inf ormation, see Descr iption of the P roperties (p.2013 ). 47.5.13. Compr essible Liquid D ialo g Box The Compr essible Liquid dialo g box allo ws you t o mo del liquid c ompr essibilit y for high pr essur e applic ations using the Tait equa tion of sta te.This dialo g box will op en when y ou selec t compr essible- liquid in the dr op-do wn list ne xt to one of the Properties in the Create/Edit M aterials D ialog Box (p.3386 ). See Compr essible Liquid D ensit y Metho d (p.1100 ) for details ab out using the it ems b elow. 3405Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Materials Task P ageControls Referenc e Pressur e sets the r eference pr essur e. Referenc e Densit y sets the r eference densit y. Referenc e Bulk M odulus sets the r eference bulk mo dulus . Densit y Exponen t sets the densit y exponen t. 47.5.14. User-D efined F unc tions D ialo g Box The User-D efined F unc tions dialo g box allo ws you t o cho ose which user-defined func tion is t o be used t o define a ma terial pr operty.This dialo g box will op en when y ou selec t user-defined in the drop-do wn list ne xt to one of the Properties in the Create/Edit M aterials D ialog Box (p.3386 ). See the separ ate Fluen t Customiza tion M anual for details ab out user-defined func tions . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3406Task P age R eference GuideThe list will c ontain all a vailable user-defined func tions . 47.5.15. Suther land L aw D ialo g Box The Suther land L aw dialo g box allo ws you t o set the c oefficien ts for Suther land ’s law for visc osity. This dialo g box will op en when y ou selec t suther land in the dr op-do wn list ne xt to Visc osit y in the Create/Edit M aterials D ialog Box (p.3386 ). See Suther land Viscosity La w (p.1109 ) for details ab out the items b elow. Controls Metho ds contains options f or selec ting the Two Coefficien t Metho d or the Three C oefficien t Metho d. C1, C2 set the c oefficien ts and in Equa tion 8.23 (p.1109 ) in SI units .These inputs will app ear if y ou selec t the Two Coefficien t Metho d. 3407Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Materials Task P ageReferenc e Visc osit y sets the r eference visc osity in Equa tion 8.24 (p.1109 ).This input will app ear if y ou selec t the Three Coefficien t Metho d. Referenc e Temp erature sets the r eference temp erature in Equa tion 8.24 (p.1109 ).This input will app ear if y ou selec t the Three Coefficien t Metho d. Effective Temp erature sets the eff ective temp erature in Equa tion 8.24 (p.1109 ).This input will app ear if y ou selec t the Three Coefficien t Metho d. 47.5.16. Power L aw D ialo g Box The Power L aw dialo g box allo ws you t o set the c oefficien ts for the p ower la w for visc osity.This dialo g box will op en when y ou selec t power-la w in the dr op-do wn list ne xt to Visc osit y in the Create/Edit Materials D ialog Box (p.3386 ). See Power-La w Viscosity La w (p.1110 ) for details ab out the it ems b elow. Controls Metho ds contains options f or selec ting the Two Coefficien t Metho d or the Three C oefficien t Metho d. B sets the c oefficien t in Equa tion 8.25 (p.1110 ) in SI units .This input will app ear if y ou selec t the Two Coefficien t Metho d. Referenc e Visc osit y sets the r eference visc osity in Equa tion 8.26 (p.1110 ).This input will app ear if y ou selec t the Three Coefficien t Metho d. Referenc e Temp erature sets the r eference temp erature in Equa tion 8.26 (p.1110 ).This input will app ear if y ou selec t the Three Coefficien t Metho d. Temp erature Exponen t sets the t emp erature exponen t in Equa tion 8.25 (p.1110 ) or Equa tion 8.26 (p.1110 ), dep ending on y our Metho d selec tion. If you ar e using the Two Coefficien t Metho d, this input must b e in SI units . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3408Task P age R eference Guide47.5.17. Non-N ewtonian P ower L aw D ialo g Box The Non-N ewtonian P ower L aw dialo g box allo ws you t o set the par amet ers f or the non-N ewtonian power la w for visc osity.This dialo g box will op en when y ou selec t non-ne wtonian-p ower-la w in the drop-do wn list ne xt to Visc osit y in the Create/Edit M aterials D ialog Box (p.3386 ). See Power La w for Non-N ewtonian Viscosity (p.1113 ) for details ab out the it ems b elow. Controls Metho ds allows you t o selec t the t ype of dep endenc y on the visc osity. Shear R ate Dependen t is wher e the visc osity is dep enden t on the shear r ate. Shear R ate and Temp erature Dependen t is wher e the visc osity is dep enden t on the shear r ate and the t emp erature. Consist enc y Inde x sets the c onsist ency inde x in Equa tion 8.38 (p.1113 ). Power-L aw Inde x sets the p ower-la w inde x in Equa tion 8.38 (p.1113 ). Minimum Visc osit y Limit , Maximum Visc osit y Limit set the minimum and maximum visc osity limits . Referenc e Temp erature sets the r eference temp erature. Activation E nergy/R, alpha is the r atio of the ac tivation ener gy to the ther modynamic c onstan t in Equa tion 8.37 (p.1113 ). 47.5.18. Carreau M odel D ialo g Box The Carreau M odel dialo g box allo ws you t o set the par amet ers f or the non-N ewtonian C arreau model f or visc osity.This dialo g box will op en when y ou selec t carreau in the dr op-do wn list ne xt to 3409Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Materials Task P ageVisc osit y in the Create/Edit M aterials D ialog Box (p.3386 ). See The C arreau M odel f or P seudo- Plastics (p.1114 ) for details ab out the it ems b elow. Controls Metho ds allows you t o selec t the t ype of dep endenc y on the visc osity. Shear R ate Dependen t is wher e the visc osity is dep enden t on the shear r ate. Shear R ate and Temp erature Dependen t is wher e the visc osity is dep enden t on the shear r ate and the t emp erature. Time C onstan t, lamb da sets the time c onstan t in Equa tion 8.39 (p.1114 ). Power-L aw Inde x sets the p ower-la w inde x in Equa tion 8.39 (p.1114 ). Zero Shear Visc osit y, Infinit e Shear Visc osit y set the z ero and infinit e shear visc osity limits and in Equa tion 8.39 (p.1114 ). Referenc e Temp erature,T_alpha sets the r eference temp erature in Equa tion 8.39 (p.1114 ). Activation E nergy/R, alpha is the r atio of the ac tivation ener gy to the ther modynamic c onstan t in Equa tion 8.37 (p.1113 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3410Task P age R eference Guide47.5.19. Cross M odel D ialo g Box The Cross M odel dialo g box allo ws you t o set the par amet ers f or the non-N ewtonian C ross mo del f or viscosity.This dialo g box will op en when y ou selec t cross in the dr op-do wn list ne xt to Visc osit y in the Create/Edit M aterials D ialog Box (p.3386 ). See Cross M odel (p.1115 ) for details ab out the it ems b elow. Controls Metho ds allows you t o selec t the t ype of dep endenc y on the visc osity. Shear R ate Dependen t is wher e the visc osity is dep enden t on the shear r ate. Shear R ate and Temp erature Dependen t is wher e the visc osity is dep enden t on the shear r ate and the t emp erature. Zero Shear Visc osit y sets the z ero shear visc osity limit in Equa tion 8.40 (p.1115 ). Power-L aw Inde x sets the p ower-la w inde x in Equa tion 8.40 (p.1115 ). Time C onstan t sets the time c onstan t in Equa tion 8.40 (p.1115 ). Referenc e Temp erature,T_alpha sets the r eference temp erature in Equa tion 8.39 (p.1114 ). Activation E nergy/R, alpha is the r atio of the ac tivation ener gy to the ther modynamic c onstan t in Equa tion 8.37 (p.1113 ). 47.5.20. Herschel-Bulk ley Dialo g Box The Herschel-Bulk ley dialo g box allo ws you t o set the par amet ers f or the non-N ewtonian H erschel- Bulkley mo del f or visc osity.This dialo g box will op en when y ou selec t herschel-bulk ley in the dr op- 3411Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Materials Task P agedown list ne xt to Visc osit y in the Create/Edit M aterials D ialog Box (p.3386 ). See Herschel-B ulkley Model for B ingham P lastics (p.1116 ) for details ab out the it ems b elow. Controls Metho ds allows you t o selec t the t ype of dep endenc y on the visc osity. Shear R ate Dependen t is wher e the visc osity is dep enden t on the shear r ate. Shear R ate and Temp erature Dependen t is wher e the visc osity is dep enden t on the shear r ate and the t emp erature. Consist enc y Inde x sets the c onsist ency inde x in Equa tion 8.42 (p.1116 ). Power-L aw Inde x sets the p ower-la w inde x in Equa tion 8.42 (p.1116 ). Yield S tress Threshold sets the yield str ess thr eshold in Equa tion 8.42 (p.1116 ). Critical S hear R ate set the cr itical shear r ate in Equa tion 8.42 (p.1116 ). Referenc e Temp erature,T_alpha sets the r eference temp erature in Equa tion 8.37 (p.1113 ). Activation E nergy/R, alpha is the r atio of the ac tivation ener gy to the ther modynamic c onstan t in Equa tion 8.37 (p.1113 ). 47.5.21. Biaxial C onduc tivit y Dialo g Box The Biaxial C onduc tivit y dialo g box allo ws you t o define a biaxial or thotr opic ther mal c onduc tivit y, which is applic able t o solid ma terials used f or the w all shell c onduc tion mo del. This dialo g box will open when y ou selec t biaxial in the dr op-do wn list ne xt to Thermal C onduc tivit y in the Create/Edit Materials D ialog Box (p.3386 ). See Biaxial Thermal C onduc tivit y (p.1122 ) for details ab out the it ems b elow. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3412Task P age R eference GuideControls Planar C onduc tivit y specifies the c onduc tivit y within the shell (or solid) r egion. Transv erse C onduc tivit y specifies the c onduc tivit y nor mal t o the sur face of the solid r egion. 47.5.22. Cylindr ical Or thotr opic C onduc tivit y Dialo g Box The Cylindr ical Or thotr opic C onduc tivit y dialo g box allo ws you t o define an or thotr opic ther mal conduc tivit y in c ylindr ical coordina tes.This dialo g box will op en when y ou selec t cyl-or thotr opic in the dr op-do wn list ne xt to Thermal C onduc tivit y in the Create/Edit M aterials D ialog Box (p.3386 ). See Cylindr ical Or thotr opic Thermal C onduc tivit y (p.1125 ) for details ab out the it ems b elow. 3413Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Materials Task P ageControls Axis Or igin allows you t o sp ecify the or igin of the c ylindr ical coordina te sy stem. X,Y, Z specify the X, Y, and (f or 3D c ases) Z c oordina tes. Axis D irection (3D only) allo ws you t o sp ecify the dir ection of the axis . X,Y, Z specify 1 against the dir ection of the axis . Radial C onduc tivit y specifies the c onduc tivit y in the r adial dir ection. Tangen tial C onduc tivit y specifies the c onduc tivit y in the tangen tial dir ection. Axial C onduc tivit y (3D only) sp ecifies the c onduc tivit y in the axial dir ection. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3414Task P age R eference Guide47.5.23. Orthotr opic C onduc tivit y Dialo g Box The Orthotr opic C onduc tivit y dialo g box allo ws you t o define an or thotr opic ther mal c onduc tivit y for a solid ma terial, using pr incipal dir ections tha t do not ha ve to aligned with the global c oordina te system of the simula tion. This dialo g box will op en when y ou selec t orthotr opic in the dr op-do wn list ne xt to Thermal C onduc tivit y in the Create/Edit M aterials D ialog Box (p.3386 ). See Orthotr opic Thermal C onduc tivit y (p.1123 ) for details ab out the it ems b elow. Controls Direction 0 C omp onen ts, Direction 1 C omp onen ts specify the dir ections and in Equa tion 8.53 (p.1123 ) as X,Y,Z vectors. For 2D c ases , only Direction 0 Comp onen ts will app ear. Conduc tivit y 0, Conduc tivit y 1, Conduc tivit y 2 specify , , and in Equa tion 8.53 (p.1123 ) as constan t,polynomial ,piec ewise-linear , or piec ewise-p olynomial func tions of t emp erature. For 2D c ases , only Conduc tivit y 0 and Conduc tivit y 1 will app ear. 3415Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Materials Task P ageEdit... opens the appr opriate dialo g box so y ou c an en ter a t emp erature-dep enden t conduc tivit y. (This butt on will b e una vailable if y ou sp ecify a constan t conduc tivit y.) 47.5.24. Anisotr opic C onduc tion - P rincipal C omp onen ts D ialo g Box The Anisotr opic C onduc tion - P rincipal C omp onen ts dialo g box allo ws you t o define an anisotr opic ther mal c onduc tivit y using the c omp onen ts of the pr incipal ax es (which do not ha ve to be or thogonal and/or aligned with the global c oordina te sy stem) and the asso ciated pr incipal v alues .This dialo g box will op en when y ou selec t principal-ax es-v alues in the dr op-do wn list ne xt to Thermal C onduc tivit y in the Create/Edit M aterials D ialog Box (p.3386 ). See Principal A xes and P rincipal Values (p.1126 ) for details about the it ems tha t follow. Controls Principal A xes specifies the , , and comp onen ts of the , , and vectors (in Equa tion 8.54 (p.1126 )) tha t define the pr incipal ax es of the anisotr opic ma terial. Note tha t these v ectors must b e linear ly indep enden t. Principal Values specifies the pr incipal v alues ( , , and in Equa tion 8.57 (p.1127 )) asso ciated with the pr incipal ax es. Conduc tivit y specifies the v alue of (in Equa tion 8.57 (p.1127 )) as a constan t, func tion of t emp erature (polynomial , piec ewise-linear ,piec ewise-p olynomial ), or user-defined func tion. Edit... opens the appr opriate dialo g box for the definition of a t emp erature-dep enden t or user-defined c onduc t- ivity. (This butt on will b e una vailable if y ou sp ecify a constan t conduc tivit y.) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3416Task P age R eference Guide47.5.25. Anisotr opic C onduc tivit y Dialo g Box The Anisotr opic C onduc tivit y dialo g box allo ws you t o define a gener al anisotr opic ther mal c onduc t- ivity.This dialo g box will op en when y ou selec t anisotr opic in the dr op-do wn list ne xt to Thermal Conduc tivit y in the Create/Edit M aterials D ialog Box (p.3386 ). See Anisotr opic Thermal C onduc tiv- ity (p.1121 ) for details ab out the it ems b elow. Controls Matrix C omp onen ts specify the c omp onen ts of the ma trix in Equa tion 8.52 (p.1121 ). Conduc tivit y specifies the v alue of in Equa tion 8.52 (p.1121 ) as a constan t, func tion of t emp erature (polynomial , piec ewise-linear ,piec ewise-p olynomial ), or user-defined func tion. Edit... opens the appr opriate dialo g box so y ou c an en ter a t emp erature-dep enden t or user-defined c onduc tivit y. (This butt on will b e una vailable if y ou sp ecify a constan t conduc tivit y.) 47.5.26. Species D ialo g Box The Species dialo g box (op ened b y click ing the Edit... butt on ne xt to Mixture Species in the Create/Edit Materials D ialog Box (p.3386 ))) allo ws you t o define the sp ecies tha t mak e up a mix ture ma terial. See Defining the S pecies in the M ixture (p.1630 ) for details ab out the it ems b elow. (Note tha t the Species dialo g box is a mo dal dialo g box, which means tha t you must t end t o it imme- diately b efore continuing the pr operty definitions .) 3417Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Materials Task P ageControls Mixture shows the name of the mix ture ma terial for which y ou ar e defining the sp ecies .This field is not editable . Available M aterials is a list of all of the ma terials t o be a c omp onen t in the mix ture ma terial b y selec ting it and click ing the Add butt on b elow the Selec ted S pecies or Selec ted S urface Species list. To add a ma terial to the Available M aterials list, use the Fluen t Database M aterials D ialog Box (p.3396 ) to copy the fluid ma terial to local st orage. Selec ted S pecies is a list of all the fluid-phase sp ecies in the mix ture.You c an mo dify the list as f ollows: •To add a ma terial to the list , selec t it in the Available M aterials list and click the Add butt on b elow the Selec ted S pecies list. •To remo ve a ma terial, selec t it in the Selec ted S pecies list and click Remo ve. •To mo ve a bulk sp ecies t o the b ottom of the Selec ted S pecies list, selec t the sp ecies and click Last Species .The tr ansp ort equa tion will not b e solv ed f or the last sp ecies . See Overview of the S pecies D ialog Box (p.1631 ) for mor e inf ormation. Selec ted S olid S pecies is a list of all the solid sp ecies in the mix ture.To add a ma terial to the list , selec t it in the Available M ater- ials list and click the Add butt on b elow the Selec ted S olid S pecies list. To remo ve a ma terial, selec t it in the Selec ted S olid S pecies list and click Remo ve. See Overview of the S pecies D ialog Box (p.1631 ) for mor e inf ormation. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3418Task P age R eference GuideSelec ted S ite Species is a list of all the sit e sp ecies in the mix ture.To add a ma terial to the list , selec t it in the Available M ater- ials list and click the Add butt on b elow the Selec ted S ite Species list. To remo ve a ma terial, selec t it in the Selec ted S ite Species list and click Remo ve. See Overview of the S pecies D ialog Box (p.1631 ) for mor e information. 47.5.27. Reac tions D ialo g Box The Reac tions dialo g box (op ened b y click ing the Edit... butt on ne xt to Reac tion in the Create/Edit Materials D ialog Box (p.3386 )) allo ws you t o define the r eactions f or a mix ture ma terial. See Defining Reactions (p.1634 ) for details ab out using this dialo g box. (Note tha t the Reac tions dialo g box is a mo dal dialo g box, which means tha t you must t end t o it im- media tely b efore continuing the pr operty definitions .) Controls 3419Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Materials Task P ageMixture shows the name of the mix ture ma terial for which y ou ar e defining the sp ecies .This field is not editable . Total N umb er of Reac tions sets the t otal numb er of r eactions (fluid-phase r eactions and sur face reactions o ccur ring a t wall b oundar ies). Use the ar rows to change the v alue , or t ype in the v alue and pr ess RETURN . Reac tion N ame contains the name of the r eaction. ID sets the numb er of the r eaction y ou w ant to define . (Again, if you t ype in the v alue b e sur e to pr ess RE- TURN .) Reac tion Type contains options tha t allo w you t o sp ecify the t ype of r eaction. Volumetr ic specifies , if enabled , tha t the cur rent reaction is a v olumetr ic reaction. Wall S urface specifies , if enabled , tha t the cur rent reaction is a w all sur face reaction. Particle S urface specifies , if enabled , tha t the cur rent reaction is a par ticle sur face reaction. Numb er of Reac tants indic ates the numb er of r eactants in the sp ecified r eaction. Species contains dr op-do wn lists of all sp ecies in the mix ture. (The numb er of lists will b e equal t o the Numb er of Reac tants.) Selec t each r eactant in one of these lists . Stoich. Coefficien t specifies the st oichiometr ic coefficien t of the r eactant species in the r eaction. Rate Exponen t specifies the r ate constan t for the r eactant species in the r eaction. Numb er of P roduc ts indic ates the numb er of pr oduc ts in the sp ecified r eaction. Species contains dr op-do wn lists of all sp ecies in the mix ture. (The numb er of lists will b e equal t o the Numb er of P roduc ts.) Selec t each pr oduc t in one of these lists . Stoich. Coefficien t specifies the st oichiometr ic coefficien t of the pr oduc t species in the r eaction. Rate Exponen t specifies the r ate constan t for the pr oduc t species in the r eaction. Arrhenius R ate contains inputs r elated t o the A rrhenius r ate. (If you ha ve chosen Eddy-D issipa tion for the Turbulenc e- Chemistr y In teraction in the Species M odel D ialog Box (p.3294 ), these inputs ar e not r equir ed.) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3420Task P age R eference GuidePre-exponen tial F actor is the c onstan t in Equa tion 7.9 in the Theor y Guide .The units of must b e sp ecified such tha t the units of the molar r eaction r ate, (Equa tion 7.5 in the Theor y Guide , are moles/v olume-time (for e xample , kmol/ -s) and the units of the v olumetr ic reaction r ate, in Equa tion 7.5 in the Theor y Guide , are mass/v olume-time (f or e xample , kg/ -s). Imp ortant It is imp ortant to not e tha t if y ou ha ve selec ted the B ritish units sy stem, the A rrhe- nius fac tor should still b e sp ecified in SI units .This is b ecause ANSY S Fluen t applies no c onversion fac tor to the v alue y ou en ter for (the c onversion fac tor is 1.0) when you w ork in B ritish units , as the c orrect conversion fac tor dep ends on y our v alues for , , and so on. Activation E nergy is the c onstan t in the f orward rate constan t expression, Equa tion 7.9 in the Theor y Guide ). Temp erature Exponen t is the v alue f or the c onstan t in Equa tion 7.9 in the Theor y Guide . Include B ack ward Reac tion specifies tha t the r eaction is r eversible . By default , the back ward reaction r ate constan t will b e com- puted fr om Equa tion 7.9 in the Fluent Theor y Guide .You c an sp ecify y our o wn back ward reaction r ate paramet ers in the Backward Reaction P aramet ers D ialog Box (p.3423 ). In this c ase, the back ward reaction rate constan t will b e comput ed fr om Equa tion 7.14 in the Fluent Theor y Guide . Third-B ody Efficiencies allows you t o sp ecify and use thir d-body efficiencies ( in Equa tion 7.8 in the Theor y Guide ).These inputs ar e optional. (This it em is a vailable only if y ou ha ve selec ted Volumetr ic for the Reac tion Type.) Pressur e-D ependen t Reac tion enables the mo deling of a pr essur e fall-off r eaction. See Inputs f or R eaction D efinition (p.1634 )Finit e- Rate/N o TCI or Eddy-D issipa tion C onc ept for the Turbulenc e-Chemistr y In teraction in the Species Model D ialog Box (p.3294 ) and ha ve selec ted Volumetr ic for the Reac tion Type.) Coverage-D ependen t Reac tion is used when mo deling Wall S urface reactions with sit e-balancing and r eaction r ates dep end on sit e coverages . Specify ... opens the Backward Reaction P aramet ers D ialog Box (p.3423 ),Third-Body Efficienc y Dialog Box (p.3423 ), the Pressur e-Dependen t Reaction D ialog Box (p.3424 ), or Coverage-D ependen t Reaction D ialog Box (p.3426 ) in which y ou c an sp ecify the back ward rate par amet ers f or the r eversible r eaction, thir d- body efficiencies , pressur e-dep enden t reaction par amet ers, or c overage par amet ers. Mixing R ate contains inputs r elated t o the mixing r ate. (If you ha ve chosen Finit e-Rate/N o TCI or Eddy-D issipa tion Conc ept for the Turbulenc e-Chemistr y In teraction in the Species M odel D ialog Box (p.3294 ), these inputs are not r equir ed.) 3421Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Materials Task P ageA is the c onstan t in the turbulen t mixing r ate (Equa tion 7.25 and Equa tion 7.26 in the Theor y Guide ) when it is applied t o a sp ecies tha t app ears as a r eactant in this r eaction. The default setting of 4.0 is based on the empir ically der ived v alues giv en b y Magnussen and Hjer tager [72] (p.4009 ). B is the c onstan t in the turbulen t mixing r ate (Equa tion 7.26 in the Theor y Guide ) when it is applied to a sp ecies tha t app ears as a pr oduc t in this r eaction. The default setting of 0.5 is based on the em- pirically der ived v alues giv en b y Magnussen and Hjer tager [72] (p.4009 ). Particle S urface Reac tion contains inputs r elated t o a par ticle sur face reaction. See User Inputs f or P article Sur face Reactions (p.1661 ) for details . (This sec tion will app ear only if y ou ha ve selec ted Particle S urface for the Reac tion Type.) Diffusion Limit ed S pecies is a dr op-do wn list tha t allo ws you t o selec t the sp ecies f or which the c oncentration gr adien t between the bulk and the par ticle sur face is the lar gest when ther e is mor e than one gaseous r eactant tak ing part in the par ticle sur face reaction. See User Inputs f or P article Sur face Reactions (p.1661 ) for details . Diffusion R ate Constan t is the c onstan t in Equa tion 7.75 in the Theor y Guide . Effectiveness F actor is the c onstan t in Equa tion 7.73 in the Theor y Guide . Butler-V olmer/T afel P aramet ers contains inputs r elated t o an elec trochemic al reaction. See User Inputs f or E lectrochemic al Reactions (p.1664 ) for details . (This gr oup b ox app ears only if Electrochemic al is selec ted f or Reac tion Type.) Tafel P aramet ers indic ates whether the B ulter-V olmer equa tion ( Equa tion 7.84 in the Fluent Theor y Guide ) or the Tafel equa tion ( Equa tion 7.85 in the Fluent Theor y Guide ) is used in the k inetics c alcula tion. Anodic Transf er C oefficien t is the v alue of used in Equa tion 7.84 in the Fluent Theor y Guide .This it em app ears if the Tafel Paramet ers check b ox is clear ed. Catho dic Transf er C oefficien t is the v alue of used in Equa tion 7.84 in the Fluent Theor y Guide .This it em app ears if the Tafel Paramet ers check b ox is clear ed. Anodic Tafel S lope is the v alue of in Equa tion 7.85 in the Fluent Theor y Guide .This it em app ears only if the Tafel Paramet ers check b ox is selec ted. Catho dic Tafel S lope is the v alue of in Equa tion 7.85 in the Fluent Theor y Guide .This it em app ears only if the Tafel Paramet ers check b ox is selec ted. Exchange C urrent Densit y is the v alue of used in Equa tion 7.84 in the Fluent Theor y Guide Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3422Task P age R eference GuideEquilibr ium P otential is the v alue of used in Equa tion 7.86 in the Fluent Theor y Guide Specify Ref erenc e M ass F ractions ... opens the Reference Mass F ractions D ialog Box (p.3427 ). 47.5.28. Back ward Reac tion P aramet ers D ialo g Box The Back ward Reac tion P aramet ers dialo g box (op ened b y click ing Specify ... next to Include B ack- ward Reac tion in the Reactions D ialog Box (p.3419 )) allo ws you t o sp ecify y our cust om back ward rate paramet ers f or a r eversible r eaction. See Inputs f or R eaction D efinition (p.1634 ) for details . Arrhenius B ack ward Rate allows you t o sp ecify back ward rate par amet ers. Pre-Exponen tial F actor is the c onstan t in Equa tion 7.14 in the Fluent Theor y Guide . Activation E nergy is the c onstan t in the back ward rate constan t expression in Equa tion 7.14 in the Fluent Theor y Guide . Temp erature Exponen t is the c onstan t in Equa tion 7.14 in the Fluent Theor y Guide . 47.5.29. Third-B ody Efficienc y Dialo g Box The Third-B ody Efficienc y dialo g box (op ened b y click ing Specify ... next to the Third-B ody Efficiencies butt on in the Reactions D ialog Box (p.3419 )) allo ws you t o sp ecify the thir d-body efficiencies f or each species in the mix ture, to be used in Equa tion 7.8 in the Theor y Guide . See Defining R eactions (p.1634 ) for details . (Note tha t the Third-B ody Efficienc y dialo g box is a mo dal dialo g box, which means tha t you must tend t o it immedia tely b efore continuing the pr operty definitions .) 3423Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Materials Task P ageControls Species displa ys the name of each sp ecies in the mix ture. Third-b ody Efficienc y specifies the thir d-body efficienc y for each sp ecies . 47.5.30. Pressur e-D ependen t Reac tion D ialo g Box The Pressur e-D ependen t Reac tion dialo g box (op ened b y click ing Specify ... under Pressur e-D epend- ent Reac tion in the Reactions D ialog Box (p.3419 )) allo ws you t o sp ecify par amet ers f or a pr essur e fall- off r eaction. See Inputs f or R eaction D efinition (p.1634 ) for details . (Note tha t the Pressur e-D ependen t Reac tion dialo g box is a mo dal dialo g box, which means tha t you must t end t o it immedia tely b efore continuing the pr operty definitions .) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3424Task P age R eference GuideControls Reac tion P aramet ers contains inputs f or sp ecifying the t ype of pr essur e fall-off r eaction and the r eaction par amet ers. See Pressur e-Dependen t Reactions in the Theor y Guide for details . Reac tion Type contains a dr op-do wn list of the a vailable r eaction t ypes:lindemann ,troe, and sri. See Pressur e-De- penden t Reactions in the Theor y Guide for details . Bath G as C onc entration allows you t o sp ecify if the ba th gas c oncentration ( in Equa tion 7.18 in the Theor y Guide ) is t o be defined as the c oncentration of the mix ture, or as the c oncentration of one of the mix ture’s con- stituen t species . Chemic ally A ctivated Bimolecular Reac tion results in a net r ate constan t at an y pr essur e being defined as Equa tion 7.24 in the Theor y Guide . Low P ressur e Arrhenius R ate contains inputs f or sp ecifying lo w-pr essur e Arrhenius par amet ers. ln(P re-exponen tial F actor) is the na tural lo garithm of the c onstan t in Equa tion 7.16 in the Theor y Guide .The pr e-exponen tial factor is of ten an e xtremely lar ge numb er, so y ou will en ter the na tural lo garithm of this t erm. 3425Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Materials Task P ageActivation E nergy is the c onstan t in Equa tion 7.16 in the Theor y Guide . Temp erature Exponen t is the c onstan t in Equa tion 7.16 in the Theor y Guide . Troe par amet ers contains inputs f or sp ecifying par amet ers f or the Troe metho d. See Pressur e-Dependen t Reactions in the Theor y Guide for details . (This sec tion of the dialo g box will app ear only if y ou ha ve selec ted troe as the Reac tion Type.) Alpha is the c onstan t in Equa tion 7.21 in the Theor y Guide . T1 is the c onstan t in Equa tion 7.21 in the Theor y Guide . T2 is the c onstan t in Equa tion 7.21 in the Theor y Guide . T3 is the c onstan t in Equa tion 7.21 in the Theor y Guide . SRI P aramet ers contains inputs f or sp ecifying par amet ers f or the SRI metho d. See Pressur e-Dependen t Reactions in the Theor y Guide for details . (This sec tion of the dialo g box will app ear only if y ou ha ve selec ted sri as the Reac tion Type.) a is the c onstan t in Equa tion 7.22 in the Theor y Guide . b is the c onstan t in Equa tion 7.22 in the Theor y Guide . c is the c onstan t in Equa tion 7.22 in the Theor y Guide . d is the c onstan t in Equa tion 7.22 in the Theor y Guide . e is the c onstan t in Equa tion 7.22 in the Theor y Guide . 47.5.31. Coverage-D ependen t Reac tion D ialo g Box The Coverage-D ependen t Reac tion dialo g box (op ened b y click ing on Specify ... under Coverage- Dependen t Reac tion in the Reactions D ialog Box (p.3419 )) allo ws you t o mo del Wall S urface reactions with sit e-balancing . (Note tha t the Coverage-D ependen t Reac tion dialo g box is a mo dal dialo g box, which means tha t you must t end t o it immedia tely b efore continuing the pr operty definitions .) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3426Task P age R eference GuideControls Species are the sit e sp ecies of the r eaction. Eta is the sur face coverage r ate mo dific ation of the sp ecies and is defined in Equa tion 7.52 in the Theor y Guide . Mu is the sur face coverage r ate mo dific ation of the sp ecies and is defined in Equa tion 7.52 in the Theor y Guide . Eps is the sur face coverage r ate mo dific ation of the sp ecies and is defined in Equa tion 7.52 in the Theor y Guide . 47.5.32. Ref erenc e M ass F ractions D ialo g Box The Referenc e M ass F ractions dialo g box (op ened b y click ing Specify Ref erenc e M ass F ractions ... under Butler-V olmer/T afel P aramet ers in the Reactions D ialog Box (p.3419 )) allo ws you t o sp ecify reference sp ecies mass fr actions f or the elec trochemic al reaction. (Note tha t the Referenc e M ass F ractions dialo g box is a mo dal dialo g box, which means tha t you must t end t o it immedia tely b efore continuing the pr operty definitions .) 3427Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Materials Task P ageControls Species are the elec trochemic al reaction sp ecies used in the B utler-V olmer equa tion ( Equa tion 7.84 in the Fluent Theor y Guide ). Referenc e M ass F ractions contains inputs f or the r eference mass fr actions of elec trochemic al reaction sp ecies ( in Equa tion 7.84 ). 47.5.33. Reac tion M echanisms D ialo g Box The Reac tion M echanisms dialo g box (op ened b y click ing the Edit... butt on ne xt to Mechanism in the Create/Edit M aterials D ialog Box (p.3386 )) allo ws you t o selec t the r eaction mechanism a t a par ticular zone . See Mixture M aterials (p.1615 ) for details ab out these metho ds and the r elated inputs . (Note tha t the Reac tion M echanisms dialo g box is a mo dal dialo g box, which means tha t you must tend t o it immedia tely b efore continuing the pr operty definitions .) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3428Task P age R eference GuideControls Numb er of M echanisms specifies the numb er of mechanisms pr esen t. Mechanism ID is the ID of the mechanism tha t you sp ecify . Name allows you t o en ter a name f or the mechanism. Reac tion Type specifies the t ype of r eaction t o be displa yed f or the mechanism. Volumetr ic displa ys all v olumetr ic reactions under the Reac tions list. Wall S urface displa ys all w all sur face reactions under the Reac tions list. Particle S urface displa ys all par ticle sur face reactions under the Reac tions list. Electrochemic al displa ys all elec trochemic al reactions under the Reac tions list. All displa ys all t ypes of r eactions under the Reac tions list. Reac tions displa ys the list of r eactions of the c ategor y sp ecified under Reac tion Type. 3429Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Materials Task P ageNumb er of S ites specifies the numb er of sit es a t which y ou c an sp ecify the r eaction. Site Name contains the name of the sit e. Site Densit y allows you t o sp ecify the sit e densit y of the sp ecies Define ... opens the Site Paramet ers D ialog Box (p.3430 ). 47.5.34. Site Paramet ers D ialo g Box The Site Paramet ers dialo g box (op ened b y click ing the Define ... butt on ne xt to Site D ensit y in the Reaction M echanisms D ialog Box (p.3428 )) allo ws you t o define the c overage f or each sit e sp ecies . Controls Site Name displa ys the name of sit e. Total N umb er of S ite Species specifies the t otal numb er of sit e sp ecies . Site Species allows you t o selec t the sit e sp ecies . Initial S ite Coverage allows you t o sp ecify the initial c overage of the sit e sp ecies . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3430Task P age R eference Guide47.5.35. Mass D iffusion C oefficien ts D ialo g Box The Mass D iffusion C oefficien ts dialo g box (op ened b y click ing the Edit... butt on ne xt to Mass D if- fusivit y in the Create/Edit M aterials D ialog Box (p.3386 ) allo ws you t o define the diffusion c oefficien ts of the sp ecies in the mix ture. Its contents will dep end on the metho d you selec ted f or Mass D iffusivit y. See Mass D iffusion C oefficien t Inputs (p.1146 ) for details ab out these metho ds and the r elated inputs . (Note tha t the Mass D iffusion C oefficien ts dialo g box is a mo dal dialo g box, which means tha t you must t end t o it immedia tely b efore continuing the pr operty definitions .) For the dilut e-appr ox metho d: Controls Species D i contains a selec table list of all sp ecies in the mix ture, from which y ou c an selec t each sp ecies and sp ecify its diffusion c oefficien t. Coefficien t sets the diffusion c oefficien t for the selec ted sp ecies in the mix ture. For the multic omp onen t metho d: 3431Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Materials Task P ageControls Species D i, Species Dj contain selec table lists of sp ecies in the mix ture, from which y ou c an selec t each pair of sp ecies and specify the diffusion c oefficien t of the selec ted Species D i in the selec ted Species Dj . Coefficien t sets the diffusion c oefficien t for Species D i in Species Dj (which is equiv alen t to the diffusion c oefficien t for Species Dj in Species D i). 47.5.36. Thermal D iffusion C oefficien ts D ialo g Box The Thermal D iffusion C oefficien ts dialo g box (op ened b y click ing the Edit... butt on ne xt to Thermal Diffusion C oefficien t in the Create/Edit M aterials D ialog Box (p.3386 ) allo ws you t o define the ther mal diffusion c oefficien ts of the sp ecies in the mix ture. See Thermal D iffusion C oefficien t Inputs (p.1145 ) for details ab out these metho ds and the r elated inputs . (Note tha t the Thermal D iffusion C oefficien ts dialo g box is a mo dal dialo g box, which means tha t you must t end t o it immedia tely b efore continuing the pr operty definitions .) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3432Task P age R eference GuideControls Species Thermal D i contains a selec table list of all sp ecies in the mix ture, from which y ou c an selec t each sp ecies and sp ecify its ther mal diffusion c oefficien t. Coefficien t sets the ther mal diffusion c oefficien t for the selec ted sp ecies in the mix ture. 47.5.37. UDS D iffusion C oefficien ts D ialo g Box The UDS D iffusion C oefficien ts dialo g box (op ened b y selec ting uds and click ing the Edit... butt on next to UDS D iffusivit y in the Create/Edit M aterials D ialog Box (p.3386 )) allo ws you t o define the diffusion coefficien ts for y our user-defined sc alar tr ansp ort equa tions . (Note tha t the UDS D iffusion C oefficien ts dialo g box is a mo dal dialo g box, which means tha t you must t end t o it immedia tely b efore continuing the pr operty definitions .) 3433Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Materials Task P ageControls User-D efined Sc alar D iffusion contains a selec table list of all user-defined sc alars , from which y ou c an selec t each one and sp ecify its diffusion c oefficien t. Coefficien t sets the diffusion c oefficien t for the selec ted user-defined sc alar. 47.5.38. WSGGM U ser S pecified D ialo g Box The WSGGM U ser S pecified dialo g box op ens when y ou selec t wsggm-user-sp ecified as the input metho d for a c omp osition-dep enden t Absor ption C oefficien t in the Create/Edit M aterials D ialog Box (p.3386 ) and it allo ws you t o define the pa th length f or he w eigh ted-sum-of-gr ay-gases mo del. See Inputs f or a C omp osition-D ependen t Absor ption C oefficien t (p.1138 ) for details . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3434Task P age R eference GuideControls Path L ength allows you t o set the Path L ength equal t o a mean b eam length tha t you ha ve calcula ted outside of Fluen t. 47.5.39. Gray-Band A bsor ption C oefficien t Dialo g Box The Gray-Band A bsor ption C oefficien t allo ws you t o sp ecify a diff erent absor ption c oefficien t in each gray band when y ou ar e mo deling non-gr ay radia tion with the P-1, DO , or MC mo dels (see The P-1 Model E qua tions ,The DO M odel E qua tions , or Monte Carlo (MC) R adia tion M odel Theor y in the Theor y Guide and Setting U p the P-1 M odel with N on-G ray Radia tion (p.1491 ),Defining N on-G ray Radia tion f or the DO M odel (p.1510 ), or Setting U p the MC M odel (p.1512 )).This dialo g box will op en when y ou selec t gray-band in the dr op-do wn list ne xt to Absor ption C oefficien t in the Create/Edit M aterials D ialog Box (p.3386 ). Controls band n specifies the absor ption c oefficien t for the th gray band . 47.5.40. Delta-E ddingt on Sc attering F unc tion D ialo g Box The Delta-E ddingt on Sc attering F unc tion dialo g box allo ws you t o define the par amet ers used in the D elta-E ddingt on phase func tion f or radia tion sc attering.This dialo g box will op en when y ou selec t delta-eddingt on in the dr op-do wn list ne xt to Scattering P hase F unc tion in the Create/Edit M aterials Dialog Box (p.3386 ). See Anisotr opic Sc attering for details ab out the it ems b elow. 3435Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Materials Task P ageControls Forward Sc attering F actor specifies the v alue of in Equa tion 5.68 in the Theor y Guide . Asymmetr y Factor specifies the v alue of in Equa tion 5.68 in the Theor y Guide . 47.5.41. Gray-Band Refr active Inde x Dialo g Box The Gray-Band Refr active Inde x allo ws you t o sp ecify a diff erent refractive inde x in each gr ay band when y ou ar e mo deling non-gr ay radia tion with the P-1, DO , or MC mo del (see The P-1 M odel E qua tions , The DO M odel E qua tions , or Monte Carlo (MC) R adia tion M odel Theor y in the Theor y Guide and Setting Up the P-1 M odel with N on-G ray Radia tion (p.1491 ),Defining N on-G ray Radia tion f or the DO M odel (p.1510 ), or Setting U p the MC M odel (p.1512 )).This dialo g box will op en when y ou selec t refractive-band in the dr op-do wn list ne xt to Refr active Inde x in the Create/Edit M aterials D ialog Box (p.3386 ). Controls Band n specifies the r efractive inde x for the th gray band . 47.5.42. Single R ate M odel D ialo g Box The Single R ate M odel dialo g box (which op ens when y ou selec t single-r ate from either the Devo- latiliza tion or Themoly sis M odel drop-do wn list in the Create/Edit M aterials D ialog Box (p.3386 )) allo ws you t o sp ecify the par amet ers used in either the single k inetic r ate de volatiliza tion mo del or single kinetic r ate Thermoly sis mo del. For mor e details ab out these mo dels , see Devolatiliza tion (La w 4) and Mass Transf er D uring La w 2—T hermoly sis in the Fluent Theor y Guide , respectively. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3436Task P age R eference GuideNote tha t the Single R ate M odel dialo g box is a mo dal dialo g box, which means tha t you must t end to it immedia tely b efore continuing the pr operty definitions . Controls Pre-exponen tial F actor sets the v alue of : •Devolatiliza tion mo del: in Equa tion 16.131 in the Theor y Guide for the c omputa tion of the k inetic rate. •Thermoly sis mo del: in Equa tion 16.109 (for dr oplet par ticles) or in Equa tion 16.186 in the Fluent Theor y Guide (for multic omp onen t par ticles). Activation E nergy sets the v alue of •Devolatiliza tion mo del: in Equa tion 16.131 in the Theor y Guide for the c omputa tion of the k inetic rate. •Thermoly sis mo del: in Equa tion 16.109 (for dr oplet par ticles) or in Equa tion 16.186 in the Fluent Theor y Guide (for multic omp onen t par ticles). 47.5.43. Two Comp eting R ates M odel D ialo g Box The Two Comp eting R ates M odel dialo g box (which op ens when y ou selec t two-comp eting-r ates as the Devolatiliza tion M odel in the Create/Edit M aterials D ialog Box (p.3386 ) allo ws you t o sp ecify the par amet ers used f or each of the c omp eting r ates in the t wo-comp eting-r ates de volatiliza tion model. See Devolatiliza tion (La w 4) in the Theor y Guide for details . Note tha t the Two Comp eting R ates M odel dialo g box is a mo dal dialo g box, which means tha t you must t end t o it immedia tely b efore continuing the pr operty definitions . 3437Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Materials Task P ageControls First R ate sets par amet ers f or the first of the t wo rates. Pre-exponen tial F actor sets the v alue of in Equa tion 16.133 in the Theor y Guide for the c omputa tion of the k inetic r ate. Activation E nergy sets the v alue of in Equa tion 16.133 in the Theor y Guide for the c omputa tion of the k inetic r ate. Weigh ting F actor sets the v alue of in Equa tion 16.135 in the Theor y Guide . Second R ate sets par amet ers f or the sec ond of the t wo rates. Pre-exponen tial F actor sets the v alue of in Equa tion 16.134 in the Theor y Guide for the c omputa tion of the k inetic r ate. Activation E nergy sets the v alue of in Equa tion 16.134 in the Theor y Guide for the c omputa tion of the k inetic r ate. Weigh ting F actor sets the v alue of in Equa tion 16.135 in the Theor y Guide . 47.5.44. CPD M odel D ialo g Box The CPD M odel dialo g box (which op ens when y ou selec t cpd-mo del as the Devolatiliza tion M odel in the Create/Edit M aterials D ialog Box (p.3386 )) allo ws you t o sp ecify the par amet ers used in the CPD devolatiliza tion mo del. See Devolatiliza tion (La w 4) in the Theor y Guide for details . Note tha t the CPD M odel dialo g box is a mo dal dialo g box, which means tha t you must t end t o it immedia tely b efore continuing the pr operty definitions . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3438Task P age R eference GuideControls Initial F raction of Br idges in C oal L attice sets the v alue of in Equa tion 16.146 in the Theor y Guide . Initial F raction of C har Br idges sets the v alue of in Equa tion 16.145 in the Theor y Guide . Lattice Coordina tion N umb er sets the v alue of in Equa tion 16.157 in the Theor y Guide . Clust er M olecular Weigh t sets the v alue of in Equa tion 16.157 in the Theor y Guide . Side C hain M olecular Weigh t sets the v alue of in Equa tion 16.156 in the Theor y Guide . 47.5.45. Kinetics/D iffusion-Limit ed C ombustion M odel D ialo g Box The Kinetics/D iffusion-Limit ed C ombustion M odel dialo g box (which op ens when y ou selec t kinet- ics/diffusion-limit ed as the Combustion M odel in the Create/Edit M aterials D ialog Box (p.3386 ) allo ws you t o sp ecify the par amet ers used f or the k inetics/diffusion-limit ed r ate sur face combustion mo del. See Surface Combustion (La w 5) in the Theor y Guide for details . Note tha t the Kinetics/D iffusion-Limit ed C ombustion M odel dialo g box is a mo dal dialo g box, which means tha t you must t end t o it immedia tely b efore continuing the pr operty definitions . 3439Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Materials Task P ageControls Mass D iffusion-Limit ed R ate Constan t sets the v alue f or in Equa tion 16.169 in the Theor y Guide . Kinetics-Limit ed R ate Pre-exponen tial F actor sets the v alue f or in Equa tion 16.170 in the Theor y Guide . Kinetics-Limit ed R ate Activation E nergy sets the v alue f or in Equa tion 16.170 in the Theor y Guide . 47.5.46. Intrinsic C ombustion M odel D ialo g Box The Intrinsic C ombustion M odel dialo g box (which op ens when y ou selec t intrinsic-mo del as the Combustion M odel in the Create/Edit M aterials D ialog Box (p.3386 ) allo ws you t o sp ecify the par amet ers used f or the in trinsic sur face combustion mo del. See Surface Combustion (La w 5) in the Theor y Guide for details . Note tha t the Intrinsic C ombustion M odel dialo g box is a mo dal dialo g box, which means tha t you must t end t o it immedia tely b efore continuing the pr operty definitions . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3440Task P age R eference GuideControls Mass D iffusion-Limit ed R ate Constan t sets the v alue f or in Equa tion 16.169 in the Theor y Guide . Kinetics-Limit ed R ate Pre-exponen tial F actor sets the v alue f or in Equa tion 16.179 in the Theor y Guide . Kinetics-Limit ed R ate Activation E nergy sets the v alue f or in Equa tion 16.179 in the Theor y Guide . Char P orosit y sets the v alue f or in Equa tion 16.176 in the Theor y Guide . Mean P ore Radius sets the v alue f or in Equa tion 16.178 in the Theor y Guide . Specific In ternal S urface Area sets the v alue f or in Equa tion 16.173 and Equa tion 16.175 in the Theor y Guide . Tortuosit y sets the v alue f or in Equa tion 16.176 in the Theor y Guide . Bur ning M ode, alpha sets the v alue f or in Equa tion 16.180 in the Theor y Guide . 47.5.47. Multiple S urface Reac tions D ialo g Box The Multiple S urface Reac tions dialo g box (which op ens when y ou selec t multiple-sur face-reac tions as the Combustion M odel in the Create/Edit M aterials D ialog Box (p.3386 )) allo ws you t o enable c om- position-dep enden t char pr operties when using the multiple sur face reactions c ombustion mo del. 3441Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Materials Task P ageControls Comp osition D ependen t Specific H eat enables c alcula tion of the char sp ecific hea t from the par ticle sp ecific hea t values . See Combustion Model (p.2015 ) for details . Comp osition D ependen t Densit y enables c alcula tion of the char densit y from the par ticle densit y values . See Combustion M odel (p.2015 ) for details . 47.5.48. Edit M aterial D ialo g Box The Edit M aterial dialo g box contains the p ortion of the Create/Edit M aterials D ialog Box (p.3386 ) tha t contains the pr operties f or a sp ecific ma terial. It is op ened fr om the Primar y Phase D ialog Box (p.3444 ), Secondar y Phase D ialog Box (p.3444 ),Wall D ialog Box (p.3549 ),Fluid D ialog Box (p.3457 ), or Solid D ialog Box (p.3467 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3442Task P age R eference GuideControls Properties of ma terial-n contains a list of the pr operties of ma terial- .The it ems in the list ar e the same as those in the Create/Edit Materials D ialog Box (p.3386 ). Change applies an y changes y ou ha ve made t o the pr operties of the ma terial. 47.6. Phases The Phases dialo g box allo ws you t o define each of the phases and the in teraction b etween them. See – Defining the P hases f or the E uler ian M odel (p.2209 ) for details . Controls Phases contains a list of all of the phases in the pr oblem fr om which y ou c an selec t the phase y ou w ant to define or mo dify. A phase c an b e a Primar y Phase or a Secondar y Phase .You c annot change a phase fr om primar y to sec ondar y, or vic e versa. Inst ead, you c an r edefine the pr operties of the pr imar y phase t o reflec t the new phase designa ted as pr imar y, and r edefine the sec ondar y phases acc ordingly as w ell. Edit... opens either the Primar y Phase D ialog Box (p.3444 ) or the Secondar y Phase D ialog Box (p.3444 ), wher e you can define the pr operties of the selec ted pr imar y or sec ondar y phase . 3443Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.PhasesInteraction... opens the Phase In teraction D ialog Box (p.3451 ), wher e you c an define the in teraction b etween the phases (for e xample , surface tension if y ou ar e using the VOF mo del, slip v elocity func tions if y ou ar e using the mixture mo del, or dr ag func tions if y ou ar e using the E uler ian mo del). ID displa ys the ID numb er of the phase .You will need this numb er only if y ou ar e wr iting a user-defined func tion. See the separ ate Fluen t Customiza tion M anual for details ab out wr iting user-defined func tions for multiphase applic ations . For additional inf ormation, see the f ollowing sec tions: 47.6.1. Primar y Phase D ialog Box 47.6.2. Secondar y Phase D ialog Box 47.6.3. Discrete Phase D ialog Box 47.6.4. Phase In teraction D ialog Box 47.6.1. Primar y Phase D ialo g Box The Primar y Phase dialo g box allo ws you t o set the pr operties of the pr imar y phase . It is op ened fr om the Phases (p.3443 ). See Defining the P hases f or the VOF M odel (p.2171 ) for details ab out the it ems b elow. Controls Name specifies the name of the phase . Phase M aterial contains a dr op-do wn list of a vailable ma terials, from which y ou c an selec t the appr opriate one f or this phase . Edit... opens the Edit M aterial D ialog Box (p.3442 ) for the selec ted Phase M aterial, wher e you c an mo dify its properties. 47.6.2. Secondar y Phase D ialo g Box The Secondar y Phase dialo g box allo ws you t o set the pr operties of a sec ondar y phase . It is op ened from the Phases (p.3443 ).The it ems tha t app ear in the Secondar y Phase dialo g box will dep end on which multiphase mo del y ou ar e using . See Defining the P hases f or the VOF M odel (p.2171 ),Defining the P hases f or the M ixture M odel (p.2189 ), and Defining the P hases f or the E uler ian M odel (p.2209 ) for details ab out the it ems b elow. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3444Task P age R eference GuideControls Name specifies the name of the phase . Phase M aterial contains a dr op-do wn list of a vailable ma terials, from which y ou c an selec t the appr opriate one f or the phase . Edit... opens the Edit M aterial D ialog Box (p.3442 ) for the selec ted Phase M aterial, wher e you c an mo dify its properties. Granular indic ates whether or not this is a solid phase .This it em app ears only f or the E uler ian mo del. 3445Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.PhasesPack ed B ed indic ates whether or not the gr anular phase is a pack ed b ed.This option app ears only if Granular is en- abled . Granular Temp erature M odel lists the gr anular t emp erature mo dels . Phase P roperty enables phase pr operty mo del f or gr anular t emp erature. Partial D ifferential E qua tion enables par tial diff erential equa tion mo del f or gr anular t emp erature. See Granular Temp erature in the Theor y Guide for details . Interfacial A rea C onc entration is used t o pr edic t mass , momen tum and ener gy transf ers thr ough the in terface between the phases . See Interfacial A rea C oncentration in the Theor y Guide for details . Properties contains a list of phase-sp ecific pr operties.This sec tion of the dialo g box will not app ear f or the VOF model. The Diamet er app ears f or b oth the mix ture mo del and the E uler ian mo del, but all of the others will app ear only f or a gr anular phase with the E uler ian mo del. Diamet er specifies the diamet er of the par ticles .You c an selec t constan t in the dr op-do wn list and sp ecify a constan t value , or selec t user-defined to use a user-defined func tion. See the separ ate Fluen t Cus- tomiza tion M anual for details ab out user-defined func tions . Granular Visc osit y specifies the k inetic par t of the gr anular visc osity of the par ticles ( in Equa tion 18.324 in the Theor y Guide ).You c an selec t constan t (the default) in the dr op-do wn list and sp ecify a c onstan t value , selec t syamlal-obr ien to comput e the v alue using Equa tion 18.326 in the Theor y Guide , selec t gidasp ow to comput e the v alue using Equa tion 18.327 in the Theor y Guide , or selec t user-defined to use a user-defined func tion. Note tha t if y ou selec t user-defined , your user-defined func tion must include b oth the k inetic p ortion and the c ollisional p ortion of the visc osity in the v alue it r etur ns. Granular Bulk Visc osit y specifies the solids bulk visc osity ( in Equa tion 18.177 in the Theor y Guide ).You c an selec t constan t (the default) in the dr op-do wn list and sp ecify a c onstan t value , selec t lun-et-al to comput e the v alue using Equa tion 18.328 in the Theor y Guide , or selec t user-defined to use a user-defined func tion. Frictional Visc osit y specifies a shear visc osity based on the visc ous-plastic flo w ( in Equa tion 18.324 in the Theor y Guide ). By default , the fr ictional visc osity is neglec ted, as indic ated b y the default selec tion of none in the dr op-do wn list. If you w ant to include the fr ictional visc osity, you c an selec t constan t and specify a c onstan t value , selec t schaeff er to comput e the v alue using Equa tion 18.329 in the Theor y Guide , or selec t user-defined to use a user-defined func tion. Angle O f Internal F riction specifies a c onstan t value f or the angle used in Schaeff er’s expression f or fr ictional visc osity (Equa tion 18.329 in the Theor y Guide ).This par amet er is r elevant only if y ou ha ve selec ted schaeff er or user-defined for the Frictional Visc osit y. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3446Task P age R eference GuideFrictional P ressur e specifies the pr essur e gr adien t term, , in the gr anular-phase momen tum equa tion. Choose none to exclude fr ictional pr essur e from y our c alcula tion, johnson-et-al to apply Equa tion 18.333 in the Theor y Guide ,syamlal-et-al to apply Equa tion 18.245 in the Theor y Guide ,based-kt gf, wher e the fr ictional pr essur e is defined b y the k inetic theor y [29] (p.4006 ).The solids pr essur e tends t o a lar ge value near the pack ing limit , dep ending on the mo del selec ted f or the r adial distr ibution func tion. You must ho ok a user-defined func tion when selec ting the user-defined option. See the separ ate Fluen t Customiza tion M anual for inf ormation on ho oking a UDF . Frictional M odulus can b e set as der ived, or as a user-defined func tion. This is defined as Equa tion 26.16 (p.2192 ). Friction P ack ing Limit specifies a thr eshold v olume fr action a t which the fr ictional r egime b ecomes dominan t.The default value is 0.61. Granular C onduc tivit y specifies the solids c onduc tivit y.You c an selec t syamlal-obr ien,gidasp ow,constan t or user-defined . Granular Temp erature specifies t emp erature for the solids phase and is pr oportional t o the k inetic ener gy of the r andom motion of the par ticles .You c an cho ose the algebr aic,constan t,dpm-a veraged ,or user-defined option. dpm-a veraged is a vailable only when using the D ense D iscrete Phase M odel (DDPM). Solids P ressur e specifies the pr essur e gr adien t term, , in the gr anular-phase momen tum equa tion. Choose either the lun-et-al , the syamlal-obr ien, the ma-ahmadi , or the user-defined option. Radial D istribution specifies a c orrection fac tor tha t mo difies the pr obabilit y of c ollisions b etween gr ains when the solid granular phase b ecomes dense . Choose either the lun-et-al , the syamlal-obr ien, the ma-ahmadi , the arastap our, or a user-defined option. Elasticit y M odulus is defined as (47.1) with . Choose either the der ived or user-defined options . Pack ing Limit specifies the maximum v olume fr action f or the gr anular phase . For mono disp ersed spher es the pack ing limit is ab out 0.63, which is the default v alue in ANSY S Fluen t. In p olydisp ersed c ases , however, smaller spher es c an fill the small gaps b etween lar ger spher es, so y ou ma y need t o incr ease the maximum pack ing limit. Surface Tension specifies the a ttractive forces b etween the in terfaces. 3447Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.PhasesCoalesc enc e Kernel allows you t o sp ecify the c oalesc ence kernel. You c an selec t none ,constan t,hibik i-ishii ,ishii-k im, yao-mor el, or user-defined .The thr ee options ,hibik i-ishii ,ishii-k im, and yao-mor el are descr ibed in detail in Interfacial A rea C oncentration in the Theor y Guide . Break age K ernel allows you t o sp ecify the br eakage k ernel. You c an selec t none ,constan t,hibik i-ishii ,ishii-k im,yao- mor el, or user-defined .The thr ee options ,hibik i-ishii ,ishii-k im, and yao-mor el are descr ibed in detail in Interfacial A rea C oncentration in the Theor y Guide . Nuclea tion R ate is a sour ce term for the in terfacial ar ea c oncentration tha t mo dels the r ate of f ormation of the disp ersed phase .You c an cho ose fr om constan t or user-defined . If the Boiling M odel option is enabled when using the E uler ian multiphase mo del, you c an also selec t yao-mor el.The yao-mor el option is descr ibed in Yao-M orel M odel in the Theor y Guide . Critical Weber N umb er will need t o be sp ecified if y ou selec ted yao-mor el for the Break age K ernel. Dissipa tion F unc tion gives y ou the option t o cho ose the f ormula which c alcula tes the dissipa tion r ate used in the hibik i- ishii and ishii-k im mo dels .You c an cho ose constan t,wu-ishii-k im,fluen t-ke, and user-defined for the dissipa tion func tion. Hydraulic D iamet er is the v alue used in Equa tion 26.18 (p.2195 ).This is a vailable when the wu-ishii-k im formula tion is se- lected as the Dissipa tion F unc tion . Min/M ax D iamet er are the limits of the bubble diamet ers. Delet e delet es this phase . 47.6.3. Discr ete Phase D ialo g Box The Discr ete Phase dialo g box allo ws you t o set the pr operties of a discr ete phase . It is op ened fr om the Phases (p.3443 ).The it ems will app ear in the Discr ete Phase dialo g box when the Dense D iscr ete Phase M odel option is enabled in the Multiphase M odel dialo g box. See Including the D ense D iscrete Phase M odel (p.2236 ) for details ab out the it ems b elow. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3448Task P age R eference GuideControls Name specifies the name of the phase . Volume F raction A ppr oaching C ontinuous F low Limit app ears f or non-gr anular flo ws.When this option is enabled , only the Transition F actor must b e sp ecified . Volume F raction A ppr oaching P ack ing Limit prevents the unlimit ed accumula tion of par ticles , which ar e op erating a t pack ing limit c onditions . Granular indic ates whether or not this is a solid phase .This it em app ears only f or the E uler ian mo del. Granular Temp erature M odel lists the gr anular t emp erature mo dels . Phase P roperty enables phase pr operty mo del f or gr anular t emp erature. 3449Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.PhasesPartial D ifferential E qua tion enables par tial diff erential equa tion mo del f or gr anular t emp erature. See Granular Temp erature in the Theor y Guide for details . Properties contains a list of phase-sp ecific pr operties. Granular Visc osit y specifies the k inetic par t of the gr anular visc osity of the par ticles ( in Equa tion 18.324 in the Theor y Guide ).You c an selec t constan t (the default) in the dr op-do wn list and sp ecify a c onstan t value , selec t syamlal-obr ien to comput e the v alue using Equa tion 18.326 in the Theor y Guide , selec t gidasp ow to comput e the v alue using Equa tion 18.327 in the Theor y Guide , or selec t user-defined to use a user-defined func tion. Granular Bulk Visc osit y specifies the solids bulk visc osity ( in Equa tion 18.177 in the Theor y Guide ).You c an selec t constan t (the default) in the dr op-do wn list and sp ecify a c onstan t value , selec t lun-et-al to comput e the v alue using Equa tion 18.328 in the Theor y Guide , or selec t user-defined to use a user-defined func tion. Frictional Visc osit y specifies a shear visc osity based on the visc ous-plastic flo w ( in Equa tion 18.324 in the Theor y Guide ). By default , the fr ictional visc osity is neglec ted, as indic ated b y the default selec tion of none in the dr op-do wn list. If you w ant to include the fr ictional visc osity, you c an selec t constan t and specify a c onstan t value , selec t schaeff er to comput e the v alue using Equa tion 18.329 in the Theor y Guide , or selec t user-defined to use a user-defined func tion. Angle O f Internal F riction specifies a c onstan t value f or the angle used in Schaeff er’s expression f or fr ictional visc osity (Equa tion 18.329 in the Theor y Guide ).This par amet er is r elevant only if y ou ha ve selec ted schaeff er or user-defined for the Frictional Visc osit y. Frictional P ressur e specifies the pr essur e gr adien t term, , in the gr anular-phase momen tum equa tion. Choose none to exclude fr ictional pr essur e from y our c alcula tion, johnson-et-al to apply Equa tion 18.333 in the Theor y Guide ,syamlal-obr ien to apply Equa tion 18.245 in the Theor y Guide ,based-kt gf, wher e the fr ictional pr essur e is defined b y the k inetic theor y [29] (p.4006 ).The solids pr essur e tends t o a lar ge value near the pack ing limit , dep ending on the mo del selec ted f or the r adial distr ibution func tion. You must ho ok a user-defined func tion when selec ting the user-defined option. See the separ ate Fluen t Customiza tion M anual for inf ormation on ho oking a UDF . Frictional M odulus can b e set as der ived, or as a user-defined func tion. This is defined as Equa tion 26.16 (p.2192 ). Friction P ack ing Limit specifies a thr eshold v olume fr action a t which the fr ictional r egime b ecomes dominan t.The default value is 0.61. Granular C onduc tivit y specifies the solids c onduc tivit y.You c an selec t syamlal-obr ien,gidasp ow,or user-defined . Solids P ressur e specifies the pr essur e gr adien t term, , in the gr anular-phase momen tum equa tion. Choose either the lun-et-al , the syamlal-obr ien, the ma-ahmadi , or the user-defined option. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3450Task P age R eference GuideRadial D istribution specifies a c orrection fac tor tha t mo difies the pr obabilit y of c ollisions b etween gr ains when the solid granular phase b ecomes dense . Choose either the lun-et-al , the syamlal-obr ien, the ma-ahmadi , the arastap our, or a user-defined option. Elasticit y M odulus is defined as (47.2) with . Choose either the der ived or user-defined options . Pack ing Limit specifies the maximum v olume fr action f or the gr anular phase . For mono disp ersed spher es the pack ing limit is ab out 0.63, which is the default v alue in ANSY S Fluen t. In p olydisp ersed c ases , however, smaller spher es c an fill the small gaps b etween lar ger spher es, so y ou ma y need t o incr ease the maximum pack ing limit. Transition F actor is sp ecified as either a constan t or a user-defined func tion. The default v alue is assumed t o be 0.75, which c orresponds t o the closest spher e pack ing f or monosiz ed spher es (a fac tor of 4/3). In other words, the tr ansition cr iterion is based on the lo cal par ticle v olume fr action of the giv en discr ete phase and is sp ecified as a fac tor multiplied b y the maximum pack ing limit (also a user sp ecified value). 47.6.4. Phase In teraction D ialo g Box The Phase In teraction dialo g box allo ws you t o define the in teraction b etween phases . It is op ened from the Phases (p.3443 ).The it ems tha t app ear in the Phase In teraction dialo g box will dep end on which multiphase mo del y ou ar e using . See Defining the P hases f or the VOF M odel (p.2171 ),Defining the P hases f or the M ixture M odel (p.2189 ), and Defining the P hases f or the E uler ian M odel (p.2209 ) for details ab out the it ems b elow. Controls Virtual M ass displa ys the Virtual M ass C oefficien t inputs .This tab is ac tive only f or the E uler ian mo dels . 3451Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.PhasesVirtual M ass M odeling includes the “virtual mass f orce” ( in Equa tion 18.305 in the Theor y Guide ) tha t is pr esen t when a secondar y phase acc elerates relative to the pr imar y phase . Implicit enables the implicit metho d for the vir tual mass f orce which c an impr ove convergenc e in some c ases . Virtual M ass Implicit Options specifies wha t form of the implicit metho d to use .Default mo dels the en tire vir tual mass f orce while Option 2 and Option 3 mo del tr uncated e xpressions which ma y fur ther impr ove convergenc e. Virtual M ass C oefficien t specifies the vir tual mass c oefficien t for each pair of phases . See Including the Virtual M ass F orce (p.2228 ) for details . Drag displa ys the Drag C oefficien t inputs .This tab is ac tive only f or the E uler ian and mix ture mo dels . Drag C oefficien t specifies the dr ag func tion f or each pair of phases .This sec tion of the dialo g box app ears only f or the Euler ian and mix ture mo dels . See Defining the P hases f or the E uler ian M odel (p.2209 ) for inf ormation about the a vailable options . Drag M odific ation enables mo dific ation of the selec ted dr ag mo dels b y a dr ag fac tor and e xpands the dialo g box to sho w the Drag F actor settings . See Drag M odific ation (p.2219 ) for additional inf ormation on using D rag M odific ation. Drag F actor specifies the dr ag fac tor to use f or mo difying the sp ecified dr ag mo del. See Drag M odific a- tion (p.2219 ) for additional inf ormation on sp ecifying the Drag F actor. Lift displa ys the Lift Coefficien t inputs .This tab is ac tive only f or the E uler ian mo del. Lift Coefficien t specifies the lif t func tion f or each pair of phases .This sec tion of the dialo g box app ears only f or the Euler ian mo del. See Defining the P hases f or the E uler ian M odel (p.2209 ) for inf ormation ab out the available options . Wall L ubr ication displa ys the Wall L ubr ication inputs .This tab is ac tive only f or the E uler ian mo del. Wall L ubr ication specifies the w all lubr ication mo del f or each pr imar y-sec ondar y phase pair .This sec tion of the dialo g box app ears only f or the E uler ian mo del. See Including the Wall L ubrication F orce (p.2221 ) for inf orm- ation ab out the a vailable options . Turbulen t Dispersion displa ys the Turbulen t Dispersion inputs .This tab is ac tive only f or the E uler ian mo del. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3452Task P age R eference GuideTurbulen t Dispersion specifies the turbulen t disp ersion mo del f or each pr imar y-sec ondar y phase pair .This sec tion of the dialo g box app ears only f or the E uler ian mo del. See Including the Turbulen t Dispersion F orce (p.2224 ) for inf ormation ab out the a vailable options . Turbulenc e In teraction displa ys the Turbulenc e In teraction inputs .This tab is ac tive only f or the E uler ian mo del. Turbulenc e In teraction specifies the turbulenc e interaction mo del f or each pr imar y-sec ondar y phase pair .This sec tion of the dialo g box app ears only f or the E uler ian mo del. See Including Turbulenc e Interaction S ource Terms (p.2231 ) for inf ormation ab out the a vailable options . Collisions displa ys the Restitution C oefficien t inputs . Restitution C oefficien t specifies the r estitution c oefficien t for collisions b etween each pair of gr anular phases , and f or collisions between par ticles of the same gr anular phase . It is r elevant only if t wo or mor e gr anular phases ar e involved. See Defining the P hases f or the E uler ian M odel (p.2209 ) for inf ormation ab out the a vailable options . Slip displa ys the Slip Velocity inputs .This tab is ac tive only f or the mix ture mo del. Slip Velocity specifies the slip v elocity func tion f or each sec ondar y phase with r espect to the pr imar y phase . See Defining the P hases f or the M ixture Model (p.2189 ) for inf ormation ab out the a vailable options . Heat displa ys the Heat Transf er C oefficien t inputs .This tab is ac tive only f or the E uler ian mo del when the ener gy equa tion is ac tive. Heat Transf er C oefficien t specifies the hea t transf er coefficien t func tion b etween each pair of phases . See Including H eat Transf er Effects (p.2233 ) for inf ormation ab out the a vailable options . Mass displa ys the Mass Transf er F unc tion inputs . Numb er of M ass Transf er M echanisms specifies the numb er of mass tr ansf er mechanisms in y our simula tion. See Including M ass Transf er Effects (p.2109 ) for inf ormation ab out the a vailable options . Reac tions allows you t o define multiple het erogeneous r eactions and st oichiometr y. Total N umb er of H eterogeneous Reac tions specifies the t otal numb er of r eactions (v olumetr ic reactions , wall sur face reactions , and par ticle sur face reactions). See Specifying H eterogeneous R eactions (p.2106 ) for inf ormation ab out the a vailable options . Heterogeneous S tiff C hemistr y Solver is used in in ter-phase r eaction mechanisms c ontaining numer ically stiff r eactions .This option c an impr ove convergenc e and is a vailable f or tr ansien t Euler ian multiphase simula tions . 3453Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.PhasesReac tion N ame allows you t o en ter a name f or the r eaction. ID enables y ou t o set the r eaction ID f or each r eaction. Numb er of Reac tants allows you t o sp ecify the numb er of r eactants tha t are involved in the r eaction. Numb er of P roduc ts allows you t o sp ecify the numb er of pr oduc ts tha t are involved in the r eaction. Phase drop-do wn list allo ws you t o selec t the phase tha t is in volved in the r eaction. Species drop-do wn list allo ws you t o selec t the sp ecies . Stoich. Coefficien t allows you t o set the st oichiometr ic coefficien t. Reac tion R ate Func tion allows you t o cho ose r ate exponen ts for an A rrhenius-t ype reaction, a user-defined func tion, or a popula tion balanc e mechanism f or the r eaction r ate. Surface Tension includes the eff ects of sur face tension along the fluid-fluid in terface. Model contains t wo sur face tension mo dels fr om which t o cho ose. Continuum S urface Force adds the sur face tension t o the VOF c alcula tion, which r esults in a sour ce term in the momen tum equa tion. This metho d is a vailable only f or the VOF and E uler ian mo dels . Continuum S urface Stress is an alt ernative way to mo deling sur face tension in a c onser vative manner c ompar ed t o the continuum sur face force metho d.This metho d is a vailable only f or the VOF and E uler ian mo dels . Adhesion Options contains options t o include w all and jump adhesion. Wall A dhesion enables the sp ecific ation of a w all adhesion angle . (The angle itself , as defined in Figur e 26.16: Meas- uring the C ontact Angle (p.2128 ), will b e sp ecified in the Wall D ialog Box (p.3549 ).) Jump A dhesion enables the tr eatmen t of the c ontact angle sp ecific ation a t the p orous jump b oundar y. (The angle itself will b e sp ecified in the Porous J ump D ialog Box (p.3518 ).) Surface Tension C oefficien ts specify the sur face tension c oefficien t, in Equa tion 18.23 and Equa tion 16.81 in the Theor y Guide , for each pair of phases . See Defining the P hases f or the VOF M odel (p.2171 ) for details . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3454Task P age R eference GuideDiscr etiza tion allows you t o use the diffusiv e and an ti-diffusiv e discr etiza tion pr ocedur e acr oss the distinc t interfaces. Phase L ocaliz ed C ompr essiv e Scheme enables the c ompr essiv e discr etiza tion scheme in ANSY S Fluen t, wher e the degr ee of diffusion/shar p- ness is c ontrolled thr ough the v alue of the slop e limit ers.This it em will app ear only f or the VOF model and f or the E uler ian mo del with Multi-F luid VOF M odel enabled . Slope Limit ers are values equa ting t o sp ecific discr etiza tion schemes . For each pair of phases , you c an en ter a v alue of 0, 1, or 2, or an y value b etween 0 and 2. Depending on the v alue y ou use , first or der up wind , sec ond order up wind , compr essiv e, or the blended scheme will b e applied . Refer to Table 26.11: Slope Limit er Discretiza tion Scheme (p.2179 ) to equa te each v alue of the slop e limit er with a discr etiza tion scheme . For mor e inf ormation, refer to Discretizing U sing the P hase L ocalized C ompr essiv e Scheme (p.2176 ). Interfacial A rea displa ys the Interfacial A rea inputs .This tab app ears only f or the M ixture multiphase mo del with in terphase mass tr ansf er and the E uler ian multiphase mo del. See Defining the A lgebr aic In terfacial A rea C oncentra- tion (p.2196 ) and Using an A lgebr aic In terfacial A rea M odel (p.2235 ) for inf ormation ab out the a vailable options . Mod.Trans'on displa ys the VOF-t o-DPM M odel Transition inputs .This tab is a vailable only when a DPM injec tion is set as descr ibed in Setting up the VOF-t o-DPM M odel Transition (p.2183 ). Numb er of M odel Transition M echanisms specifies the numb er of VOF-t o-DPM mo del tr ansition mechanisms in y our simula tion. See Setting up the VOF-t o-DPM M odel Transition (p.2183 ) for inf ormation ab out the a vailable options . 47.7. Cell Z one C onditions Task P age The Cell Z ones C onditions task page allo ws you t o set the t ype of a c ell z one and displa y other dialo g boxes to set the c ell z one c ondition par amet ers f or each z one . See Cell Z one C onditions (p.853) for mor e inf ormation. 3455Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Cell Z one C onditions Task P ageControls Zone contains a selec table list of a vailable c ell z ones fr om which y ou c an selec t the z one of in terest.You c an check a z one t ype by using the mouse pr obe (see Controlling the M ouse B utton F unctions (p.2833 )) on the displa yed ph ysical mesh. This f eature is par ticular ly useful if y ou ar e setting up a pr oblem f or the first time , or if y ou ha ve two or mor e cell z ones of the same t ype and y ou w ant to det ermine the c ell z one IDs .To do this y ou must first displa y the mesh with the Mesh D ispla y Dialog Box (p.3239 ).Then click the b oundar y zone with the r ight (selec t) mouse butt on. ANSY S Fluen t will pr int the c ell z one ID and t ype of tha t boundar y zone in the c onsole windo w. Phase specifies the phase f or which c onditions a t the selec ted c ell Zone are being set. This it em app ears if the VOF, mix ture, or E uler ian multiphase mo del is b eing used . See Defining M ultiphase C ell Z one and B oundar y Conditions (p.2124 ) for details . Type contains a dr op-do wn list of c ondition t ypes for the selec ted c ell z one .The list c ontains all p ossible t ypes to which the c ell z one c an b e changed . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3456Task P age R eference GuideID displa ys the c ell z one ID numb er of the selec ted c ell z one . (This is f or inf ormational pur poses only ; you cannot edit this numb er.) Edit... opens the Fluid D ialog Box (p.3457 ) or Solid D ialog Box (p.3467 ). Copy... opens the Copy Conditions D ialog Box (p.3469 ), which allo ws you t o copy conditions fr om one c ell z one t o other c ell z ones of the same t ype. See Copying C ell Z one and B oundar y Conditions (p.840) for details . Profiles ... opens the Profiles D ialog Box (p.3473 ). Paramet ers... opens the Paramet ers D ialog Box (p.3738 ). Operating C onditions ... opens the Operating C onditions D ialog Box (p.3470 ). Displa y M esh... opens the Mesh D ispla y Dialog Box (p.3239 ). Porous F ormula tion contains options f or setting the v elocity in the p orous medium simula tion. See Defining the P orous Velocity Formula tion (p.874) for details . Superficial Velocity enables the sup erficial v elocity in a p orous medium simula tion. This is the default metho d. Physical Velocity enables the ph ysical velocity in a p orous medium simula tion f or a mor e accur ate simula tion. This option is available only f or a pr essur e-based solv er. See Modeling P orous M edia B ased on P hysical Velo- city (p.869) for details . For additional inf ormation, see the f ollowing sec tions: 47.7.1. Fluid D ialog Box 47.7.2. Solid D ialog Box 47.7.3. Copy Conditions D ialog Box 47.7.4. Operating C onditions D ialog Box 47.7.5. Selec t Input P aramet er D ialog Box 47.7.6. Profiles D ialog Box 47.7.7. Replic ate Profile D ialog Box 47.7.8. Orient Profile D ialog Box 47.7.9. Write Profile D ialog Box 47.7.1. Fluid D ialo g Box The Fluid dialo g box sets the c onditions f or a fluid c ell z one . It is op ened fr om the Cell Z one C onditions Task P age (p.3455 ). See Inputs f or F luid Z ones (p.854) and User Inputs f or P orous M edia (p.872) for details about the it ems b elow. 3457Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Cell Z one C onditions Task P ageControls Zone N ame sets the name of the z one . Material N ame sets the fluid ma terial.The dr op-do wn list c ontains the names of all ma terials tha t ha ve been loaded in to the solv er. Materials ar e defined with the Materials Task P age (p.3384 ). Imp ortant If you ar e mo deling sp ecies tr ansp ort or multiphase flo w, the Material N ame list will not app ear in the Fluid dialo g box. For sp ecies c alcula tions , the mix ture ma terial for all fluid z ones will b e the ma terial y ou sp ecified in the Species M odel D ialog Box (p.3294 ). For multiphase flo ws, the ma terials ar e sp ecified when y ou define the phases , as de- scribed in Defining the P hases f or the VOF M odel (p.2171 ). Frame M otion enables the mo ving r eference frame mo del f or the c ell z one . See Specifying the R otation A xis (p.856) and Defining Z one M otion (p.857) for details . Mesh M otion enables the sliding mesh mo del f or the c ell z one . See Setting U p the S liding M esh P roblem (p.1258 ) for details . Porous Z one indic ates tha t the z one is a p orous medium. Additional it ems will app ear in the dialo g box when this option is enabled . See User Inputs f or P orous M edia (p.872) for details . 3D F an Z one allows you t o simula te the eff ect of an axial fan b y applying a distr ibut ed momen tum sour ce in a t oroid- shap ed fluid v olume .This mo del c an c alcula te not only the axial v elocity, but the swir l and r adial v elocities Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3458Task P age R eference Guideas w ell.When y ou enable this option, the 3D F an Z one tab b ecomes a vailable , so tha t you c an sp ecify the geometr y and pr operties of the fan. The c ell z one should ha ve a t oroid shap e tha t is siz ed t o ma tch the blade-sw ept v olume of the fan y ou ar e simula ting (tha t is, has an inner and out er radius tha t ma tches the r adius of the fan ’s hub and blade tips , respectively, as w ell as a length tha t ma tches the thick ness of the t oroid r egion sw ept b y the blades in the axial dir ection). Further mor e, the fluid c ell z one should b e “interior”, tha t is, have at least t wo boundar y zones of t ype interior tha t border another fluid c ell z one and ac t as the fan inlet and outlet (the other b oundar ies c an b e of t ype interior as w ell). See 3D F an Zones (p.899) for details . Laminar Z one disables the c alcula tion of turbulenc e pr oduc tion in the fluid z one (app ears only f or turbulen t flo w calcu- lations using the S palar t-Allmar as mo del or one of the - or - mo dels). See Specifying a Laminar Zone (p.856) for details . LES Z one allows you t o mo del a smaller emb edded LES z one within a lar ger UR ANS c omputa tional domain f or turbulen t flo w calcula tions .When y ou tur n on this option, the Embedded LES tab will b e enabled t o allo w you t o sp ecify pr operties f or the emb edded LES z one . See Setting U p the Emb edded Lar ge E ddy Simula tion (ELES) M odel (p.1432 ) for details . Sour ce Terms enables the sp ecific ation of v olumetr ic sour ces of mass , momen tum, ener gy, and so on. When y ou tur n on this option, the Sour ce Terms tab will b e enabled t o allo w you t o sp ecify the v alues f or the desir ed sour ces. See Defining M ass, Momen tum, Ener gy, and O ther S ources (p.908) for details . Fixed Values enables the fixing of the v alue of one or mor e variables in the fluid z one , rather than c omputing them during the c alcula tion. See Fixing the Values of Variables (p.904) for details . Imp ortant You c an fix v alues f or v elocity comp onen ts, temp erature, and sp ecies mass fr actions only if y ou ar e using the pr essur e-based solv er. Participa tes In R adia tion specifies whether or not the fluid z one par ticipa tes in r adia tion. This option app ears when y ou ar e using the DO mo del f or radia tion. Warning In gener al, disabling Participa tes in R adia tion for fluid z ones is not r ecommended , as it can pr oduce er roneous r esults .There ar e rare cases when it is acc eptable: for e xample , if the domain c ontains multiple fluid z ones , disabling this option f or z ones wher e radi- ation is negligible ma y sa ve computa tional time without aff ecting the r esults . Reac tion enables/disables r eactions in the p orous z one . Electrolyt e indic ates tha t the z one is an elec trolyt e zone . By default , all fluid z ones ar e assumed t o be elec trolyt e zones .This option app ears when the Electrochemic al Reaction mo del is enabled . 3459Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Cell Z one C onditions Task P ageReferenc e Frame lists the par amet ers tha t define motion f or a mo ving r eference frame . Rota tion-A xis Or igin specifies the or igin f or the axis of r otation of solid z one . See Specifying the R otation A xis (p.860) for details .This it em will app ear only f or 3D and 2D non-axisymmetr ic mo dels . Rota tion-A xis D irection specifies the dir ection v ector for the solid z one’s axis of r otation. See Specifying the R otation A xis (p.860) for details .This it em will app ear only f or 3D mo dels . Rota tional Velocity contains an input field f or the r otational Speed of the z one . Transla tional Velocity contains inputs f or the X,Y, and Z velocities of the z one . Rela tive Specific ation indic ates whether the v elocities ar e absolut e velocities ( absolut e) or v elocities r elative to the motion of each c ell z one ( Rela tive to Cell Z one ).This selec tion is nec essar y only if y our pr oblem in volves moving r eference frames or sliding meshes . If ther e is no z one motion, both options ar e equiv alen t. UDF allows you t o ho ok the DEFINE_Z ONE_MO TION user-defined func tion. Copy to M esh M otion allows you t o swit ch b etween the MRF and mo ving mesh mo dels .The v ariables used f or the or igin, axis, and v elocity comp onen ts, as w ell as f or the DEFINE_ZONE_MOTION user-defined func tion, will be copied fr om one mo del t o the other . Mesh M otion lists the par amet ers tha t define motion f or a mo ving r eference frame . Rota tion-A xis Or igin specifies the or igin f or the axis of r otation of solid z one . See Specifying the R otation A xis (p.860) for details .This it em will app ear only f or 3D and 2D non-axisymmetr ic mo dels . Rota tion-A xis D irection specifies the dir ection v ector for the solid z one’s axis of r otation. See Specifying the R otation A xis (p.860) for details .This it em will app ear only f or 3D mo dels . Rota tional Velocity contains an input field f or the r otational Speed of the z one . Transla tional Velocity contains inputs f or the X,Y, and Z velocities of the z one . Rela tive Specific ation indic ates whether the v elocities ar e absolut e velocities ( absolut e) or v elocities r elative to the motion of each c ell z one ( Rela tive to Cell Z one ).This selec tion is nec essar y only if y our pr oblem in volves moving r eference frames or sliding meshes . If ther e is no z one motion, both options ar e equiv alen t. UDF allows you t o ho ok the DEFINE_Z ONE_MO TION user-defined func tion. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3460Task P age R eference GuideCopy to Frame M otion allows you t o swit ch b etween the MRF and mo ving mesh mo dels .The v ariables used f or the or igin, axis, and v elocity comp onen ts, as w ell as f or the DEFINE_ZONE_MOTION user-defined func tion, will be copied fr om one mo del t o the other . Porous Z one lists the par amet ers asso ciated with the p orous z one . Conic al enables the sp ecific ation of a c onic al (or c ylindr ical) p orous medium. This it em will app ear only when the Porous Z one option is enabled f or a 3D c ase. Cone H alf A ngle specifies the angle b etween the c one’s axis and its sur face (see Figur e 7.20: Cone Half A ngle (p.877)). Set this t o 0 t o define the p orous r egion using a c ylindr ical coordina te sy stem. This it em will app ear only when the Porous Z one and Conic al options ar e enabled . Snap t o Zone aligns the plane (or line , in 2D) t ool with the z one selec ted in the dr op-do wn list. The t ool is c entered at the c entroid of the z one , with the t ool’s axis nor mal t o the z one . If this axis is not the desir ed c one axis, reposition the t ool (as descr ibed in Using the P lane Tool (p.2744 )).When y ou ar e sa tisfied with the axis , click the Update From P lane Tool (or Update From Line Tool) butt on t o up date the Cone Axis Vector fields . This it em will app ear only when the Porous Z one and Conic al options ar e enabled . Update From P lane Tool (Update From Line Tool in 2D) up dates the Direction-1 Vector and (in 3D) the Direction-2 Vector from the plane t ool or ientation. If the Conic al option is enabled , this butt on will up date the Cone Axis Vector and the Point on C one A xis. See Defining the Viscous and Iner tial R esistanc e Coeffi- cien ts (p.876) for details .This it em will app ear only when the Porous Z one option is enabled . Direction-1 Vector, Direction-2 Vector indic ate the dir ections f or which the r esistanc e coefficien ts ar e defined . See Defining the Viscous and Iner tial R esistanc e Coefficien ts (p.876) for details .These it ems will app ear only when the Porous Z one option is enabled , but the Conic al option is not. (In 2D , only Direction-1 Vector will app ear.) Cone A xis Vector specifies the X,Y,Z vector for the c one’s axis . This it em will app ear only when the Porous Z one and Conic al options ar e enabled . Point on C one A xis specifies a p oint on the c one’s axis .This p oint will b e used b y ANSY S Fluen t to transf orm the r esistanc es to the C artesian c oordina te sy stem. This it em will app ear only when the Porous Z one and Conic al options ar e enabled . Rela tive Velocity Resistanc e Formula tion allows ANSY S Fluen t to either apply the r elative reference frame or the absolut e reference frame .This allows for the c orrect predic tion of the sour ce terms. 3461Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Cell Z one C onditions Task P ageVisc ous Resistanc e, Iner tial Resistanc e contain inputs f or the visc ous r esistanc e coefficien t and the iner tial r esistanc e coefficien t in each dir ection. See Defining the Viscous and Iner tial R esistanc e Coefficien ts (p.876) for details .These items will app ear only when the Porous Z one option is enabled . Alternative Formula tion provides b etter stabilit y to the c alcula tion when y our p orous medium is anisotr opic . If you ha ve enabled the Conic al option, Direction-1 is the c one axis dir ection, Direction-2 is the nor mal t o the c one sur face (radial ( ) dir ection f or a c ylinder), and Direction-3 is the cir- cumf erential ( ) dir ection. Power L aw M odel contains inputs f or the C0 and C1 coefficien ts in the p ower la w mo del f or p orous media. See Using the P ower-La w M odel (p.882) for details . Fluid P orosit y contains an additional input f or the p orous medium. See User Inputs f or P orous M edia (p.872) for details . Porosit y sets the v olume fr action of fluid within the p orous r egion. Heat Transf er S ettings contains hea t transf er settings f or the p orous medium. See Specifying the H eat Transf er Settings (p.883) for details . Thermal M odel specifies whether or not ther mal equilibr ium is assumed b etween the medium and the fluid flo w. Equilibr ium specifies tha t the medium and the fluid flo w ar e in ther mal equilibr ium in the p orous medium. Non-E quilibr ium specifies tha t the medium and the fluid flo w ar e not in ther mal equilibr ium in the p orous medium, so tha t a dual c ell appr oach is enabled . Solid M aterial N ame specifies the solid ma terial in the p orous r egion. This dr op-do wn menu is only a vailable when Equilibr ium is selec ted fr om the Thermal M odel list. Solid Z one displa ys the name of the solid c ell z one tha t is c oupled with the p orous fluid z one thr ough hea t transf er.This field is only displa yed when Non-E quilibr ium is selec ted fr om the Thermal M odel list. Interfacial A rea D ensit y specifies (as descr ibed in Non-E quilibr ium Thermal M odel E qua tions (p.868)) for the p orous region. This t ext-en try box is only a vailable when Non-E quilibr ium is selec ted fr om the Thermal Model list. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3462Task P age R eference GuideHeat Transf er C oefficien t specifies (as descr ibed in Non-E quilibr ium Thermal M odel E qua tions (p.868)) for the p orous region. This t ext-en try box is only a vailable when Non-E quilibr ium is selec ted fr om the Thermal Model list. Anisotr opic S pecies D iffusion allows you t o mo del anisotr opic sp ecies diffusion in p orous media. When this option is selec ted, you can sp ecify the Matrix C omp onen ts for the anisotr opic diffusion ma trix in the p orous z one .This option is a vailable only with the sp ecies tr ansp ort mo dels . 3D F an Z one provides the settings tha t define a 3D fan z one . See 3D F an Z ones (p.899) for details . Geometr y allows you t o define the lo cation and siz e of the fan. Inlet F an Z one allows you t o selec t a b oundar y zone of t ype interior tha t will ac t as the sur face on which the fan will b e located. Hub R adius defines the r adius of the fan hub , tha t is, the inner r adius of the blade-sw ept v olume on which the fan ’s distr ibut ed momen tum sour ces ar e applied . Tip R adius defines the r adius of the blade tips of the fan, tha t is, the out er radius of the blade-sw ept v olume on which the fan ’s distr ibut ed momen tum sour ces ar e applied . Thick ness defines the thick ness of the t oroid r egion sw ept b y the blades in the axial dir ection. Inflec tion P oint is a r atio tha t defines the fr action of the fan blade length (star ting a t the hub) o ver which the tangen tial v elocity of the fan dischar ge is incr easing with incr easing r adius and p eaks , before tapering off (see Figur e 7.28: The Inflec tion P oint Ratio of a P itched B lade Turbine (p.903)). Fan Or igin defines the X,Y, and Z coordina tes of a p oint on the Inlet F an Z one tha t is the or igin f or the fan. Properties allows you t o define ho w the fan b ehaves. Rota tional D irection allows you t o define the fan ’s rotational dir ection, using the r ight-hand r ule with r espect to the fan dir ection v ector (tha t is, a vector fr om the Fan Or igin tha t points in to the 3D fan z one p erpen- dicular t o the Inlet F an Z one ). Operating A ngular Velocity defines the angular v elocity of the fan dur ing the simula tion. Limit F low R ate Through F an specifies tha t the flo w rate thr ough the fan adher es to minimum and maximum v alues , as defined in the Flow R ate group b ox. 3463Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Cell Z one C onditions Task P ageFlow R ate allows you t o define the Maximum and Minimum flow rates thr ough the fan. This gr oup b ox is available when the Limit F low R ate Through F an option is enabled . Tangen tial S our ce Term enables a momen tum sour ce in the tangen tial dir ection, based on imp eller theor y. Radial S our ce Term enables a momen tum sour ce in the r adial dir ection, based on imp eller theor y. Axial S our ce Term enables a momen tum sour ce in the axial dir ection, based on the settings in the Axial S our ce Term S ettings group b ox. Axial S our ce Term S ettings allows you t o define the momen tum sour ce in the axial dir ection. This gr oup b ox is only a vailable when the Axial S our ce Term option is enabled . Metho d specifies whether a constan t pr essur e or a fan cur ve (tha t is, a cur ve created fr om da ta p oints that plot pr essur e rise v s. volumetr ic flo w rate) defines the axial momen tum sour ce. Pressur e Jump defines the pr essur e jump tha t is applied acr oss the 3D fan. This setting is only a vailable when constan t pr essur e is selec ted f or the Metho d. Read F an C urve... allows you t o read a tab-delimit ed ASCII file tha t defines the r elationship b etween pr essur e and flo w rate for each 3D fan c ell z one (see 3D F an C urve File F ormat (p.3987 ) for details). This butt on is only a vailable when fan cur ve is selec ted f or the Metho d. Curve Fitting M etho d specifies whether F luen t should apply a polynomial or piec ewise-linear fitting metho d to constr uct a cur ve from the da ta p oints in the fan cur ve file .This dr op-do wn list is only a vailable when fan cur ve is selec ted f or the Metho d. Order of P olynomial defines the or der of the p olynomial cur ve fitting metho d.This setting is only a vailable when polynomial is selec ted f or the Curve Fitting M etho d. Initial F low R ate specifies y our b est estima te of the initial flo w rate thr ough the fan. This setting is only a vailable when fan cur ve is selec ted f or the Metho d. Test A ngular Velocity specifies the angular v elocity of the fan used in the e xperimen t tha t gener ated the fan cur ve data.This setting is only a vailable when fan cur ve is selec ted f or the Metho d. Test Temp erature specifies the t emp erature of the fluid flo wing thr ough the fan dur ing the e xperimen t tha t gener ated the fan cur ve da ta.This setting is only a vailable when fan cur ve is selec ted f or the Metho d. Reac tion lists the par amet ers f or reactions in the p orous z one . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3464Task P age R eference GuideReac tion M echanism allows you t o sp ecify a defined gr oup , or mechanism, of a vailable r eactions . See Defining Z one-B ased Reaction M echanisms (p.1642 ) for details ab out defining r eaction mechanisms . Surface-to-Volume R atio specifies the sur face area of the p ore walls p er unit v olume ( ), and c an b e though t of as a measur e of catalyst loading .With this v alue , ANSY S Fluen t can c alcula te the t otal sur face area on which the reaction tak es plac e in each c ell b y multiplying by the v olume of the c ell. Sour ce Terms defines a sour ce of hea t, mass , momen tum, turbulenc e, species , or other sc alar quan tity within the fluid zone . Fixed Values allows you t o sp ecify which v ariables in the fluid z one ar e fix ed (as a c onstan t value or as defined by a pr ofile or user-defined func tion), rather than c omput ed dur ing the c alcula tion. See Fixing the Values of Variables (p.904) for details . Local C oordina te System f or F ixed Velocities enables the sp ecific ation of fix ed c ylindr ical velocity comp onen ts inst ead of C artesian c omp onen ts. The lo cal coordina te sy stem is defined b y the Rota tion-A xis Or igin and Rota tion-A xis D irection . This it em is a vailable only in 3D , and only when the Fixed Values option is on. Multiphase allows you t o set par amet ers tha t are sp ecific t o the multiphase mo dels . Compr essiv e Scheme S lope Limit er ranges fr om 0 t o 2. For e xample , a Compr essiv e Scheme S lope Limit er of 0 c orresponds t o first or der upwind b ehavior, a value of 1 c orresponds t o sec ond or der up wind , and a v alue of 2 applies the compr essiv e scheme .The Multiphase tab is a vailable only if Zonal D iscr etiza tion is enabled in the Multiphase M odel D ialog Box (p.3248 ). Numer ic B each Treatmen t is available when Open C hannel F low and/or Open C hannel Wave BC is enabled in the Multiphase Model dialo g box (see Numer ical Beach Treatmen t for Op en C hannels (p.2167 ) for mor e detail). Numer ical B each when enabled e xpands the dialo g box wher e you c an sp ecify the numer ical beach par amet ers. Beach G roup ID represen ts the c ell z ones shar ing the damping length c ontaining the same input par amet ers. Damping Type allows you t o cho ose b etween One D imensional and Two Dimensional damping . One D imensional is the damping tr eatmen t in the flo w dir ection. Two Dimensional is the damping tr eatmen t in the flo w and gr avity dir ection. 3465Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Cell Z one C onditions Task P ageComput e From Inlet B oundar y is set t o none by default. If ther e are available op en channel b oundar ies (v elocity-inlet , pressur e- inlet , and mass-flo w-inlet), boundar y names ar e added t o the dr op-do wn list. If you selec t a boundar y from the list , the Level Inputs ,Damping L ength Inputs in F low D irection , and Damping Resistanc e values will b e up dated in the in terface.You ha ve the option t o overwrite the up dated inputs with v alues tha t are mor e applic able t o your simula tion. Level Inputs is only a vailable f or the Two Dimensional damping t ype. Free S urface Level is the same definition as f or op en channel flo w, see Modeling Op en C hannel F lows (p.2144 ). Bottom L evel is the same definition as f or op en channel flo w, see Modeling Op en C hannel F lows (p.2144 ), and is v alid only f or shallo w w aves.The b ottom le vel is used f or calcula ting the liquid heigh t. Flow D irection is the X, Y, and Z (f or 3D) c omp onen ts. Damping L ength Inputs in F low D irection are requir ed t o calcula te the star t and end p oints of the damping length in the flo w dir ection. Damping L ength S pecific ation is only a vailable if Open C hannel Wave BC is enabled in the Multiphase M odel dialo g box. There are two options y ou c an cho ose fr om End P oint and Wave Lengths or End and S tart Points. End P oint is the end p oint of the damping z one . Start Point is the star ting p oint in the flo w dir ection. Wave Length is up dated aut oma tically if the b oundar y is selec ted fr om the Comput e From Inlet B oundar y drop-do wn list. Numb er O f Wave Lengths is set t o 2 b y default f or the c alcula tion of the damping length. Rela tive Velocity Resistanc e Formula tion calcula tes the sour ce term using r elative velocities in the numer ical beach z one when using moving/def orming meshes or mo ving r eference frames . Linear D amping Resistanc e is the r esistanc e per unit time . Quadr atic D amping Resistanc e is the r esistanc e per unit length. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3466Task P age R eference Guide47.7.2. Solid D ialo g Box The Solid dialo g box sets the b oundar y conditions f or a solid c ell z one . It is op ened fr om the Cell Z one Conditions Task P age (p.3455 ). See Inputs f or S olid Z ones (p.859) for details ab out the it ems b elow. Controls Zone N ame sets the name of the z one . Material N ame selec ts the ma terial type of the solid . Materials ar e defined with the Materials Task P age (p.3384 ). Frame M otion enables the mo ving r eference frame mo del f or the c ell z one . See Specifying the R otation A xis (p.856) and Defining Z one M otion (p.857) for details . Mesh M otion enables the sliding mesh mo del f or the c ell z one . See Setting U p the S liding M esh P roblem (p.1258 ) for details . Sour ce Terms enables the sp ecific ation of a v olumetr ic sour ce of ener gy.When y ou tur n on this option, the Sour ce Term tab will allo w you t o sp ecify the v alue f or the ener gy sour ce. See Defining M ass, Momen tum, Ener gy, and O ther S ources (p.908) for details . 3467Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Cell Z one C onditions Task P ageFixed Values enables the fixing of the v alue of one or mor e variables in the solid z one , rather than c omputing them dur ing the c alcula tion. See Fixing the Values of Variables (p.904) for details . Imp ortant You c an fix the v alue of t emp erature only if y ou ar e using the pr essur e-based solv er. Participa tes In R adia tion specifies whether or not the solid z one par ticipa tes in r adia tion. This option app ears when y ou ar e using the DO mo del f or radia tion. Referenc e Frame lists the par amet ers tha t define motion f or a mo ving r eference frame . Rota tion-A xis Or igin specifies the or igin f or the axis of r otation of solid z one . See Specifying the R otation A xis (p.860) for details .This it em will app ear only f or 3D and 2D non-axisymmetr ic mo dels . Rota tion-A xis D irection specifies the dir ection v ector for the solid z one’s axis of r otation. See Specifying the R otation A xis (p.860) for details .This it em will app ear only f or 3D mo dels . Rota tional Velocity contains an input field f or the r otational Speed of the z one . Transla tional Velocity contains inputs f or the X,Y, and Z velocities of the z one . Rela tive Specific ation indic ates whether the v elocities ar e absolut e velocities ( absolut e) or v elocities r elative to the motion of each c ell z one ( Rela tive to Cell Z one ).This selec tion is nec essar y only if y our pr oblem in volves moving r eference frames or sliding meshes . If ther e is no z one motion, both options ar e equiv alen t. UDF allows you t o ho ok the DEFINE_Z ONE_MO TION user-defined func tion. Copy to M esh M otion allows you t o swit ch b etween the MRF and mo ving mesh mo dels .The v ariables used f or the or igin, axis, and v elocity comp onen ts, as w ell as f or the DEFINE_ZONE_MOTION user-defined func tion, will be copied fr om one mo del t o the other . Mesh M otion lists the par amet ers tha t define motion f or a mo ving r eference frame . Rota tion-A xis Or igin specifies the or igin f or the axis of r otation of solid z one . See Specifying the R otation A xis (p.860) for details .This it em will app ear only f or 3D and 2D non-axisymmetr ic mo dels . Rota tion-A xis D irection specifies the dir ection v ector for the solid z one’s axis of r otation. See Specifying the R otation A xis (p.860) for details .This it em will app ear only f or 3D mo dels . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3468Task P age R eference GuideRota tional Velocity contains an input field f or the r otational Speed of the z one . Transla tional Velocity contains inputs f or the X,Y, and Z velocities of the z one . Rela tive Specific ation indic ates whether the v elocities ar e absolut e velocities ( absolut e) or v elocities r elative to the motion of each c ell z one ( Rela tive to Cell Z one ).This selec tion is nec essar y only if y our pr oblem in volves moving r eference frames or sliding meshes . If ther e is no z one motion, both options ar e equiv alen t. UDF allows you t o ho ok the DEFINE_Z ONE_MO TION user-defined func tion. Copy to Frame M otion allows you t o swit ch b etween the MRF and mo ving mesh mo dels .The v ariables used f or the or igin, axis, and v elocity comp onen ts, as w ell as f or the DEFINE_ZONE_MOTION user-defined func tion, will be copied fr om one mo del t o the other . Sour ce Term lists the par amet ers f or v olumetr ic sour ce of ener gy. Energy displa ys the t otal numb er of ener gy sour ces used . User Sc alar n displa ys the t otal numb er of sc alars used . Fixed Values allows you t o sp ecify which v ariables in the solid z one ar e fix ed (as a c onstan t value or as defined by a pr ofile or user-defined func tion), rather than c omput ed dur ing the c alcula tion. See Fixing the Values of Variables (p.904) for details . 47.7.3. Copy Conditions D ialo g Box The Copy Conditions dialo g box allo ws you t o copy cell z one and/or b oundar y conditions fr om one zone/b oundar y to other z ones/b oundar ies of the same t ype. It is op ened either fr om the Cell Z one Conditions Task P age (p.3455 ) or fr om the Boundar y Conditions Task P age (p.3479 ). See Copying C ell Zone and B oundar y Conditions (p.840) for details . 3469Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Cell Z one C onditions Task P ageControls From Z one specifies the z one tha t has the c onditions y ou w ant to copy. To Zones specifies the z one or z ones t o which y ou w ant to copy the c onditions . Phase specifies the phase f or which c ell z one c onditions or b oundar y conditions ar e being c opied .This it em app ears if the VOF, mix ture, or E uler ian multiphase mo del is b eing used . See Steps f or C opying C ell Z one and B oundar y Conditions (p.2140 ) for details . Copy copies the c ell z one c onditions or b oundar y conditions , setting all of the c onditions f or the z ones selec ted in the To Zones list t o be the same as the c onditions f or the z one selec ted in the From Z one list. 47.7.4. Op erating C onditions D ialo g Box The Operating C onditions dialo g box allo ws you t o set par amet ers r elated t o op erating c onditions in your mo del. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3470Task P age R eference GuideControls Pressur e contains it ems r elated t o the mo deling of pr essur e. Floating Op erating P ressur e specifies the use of a floa ting op erating pr essur e. See Floating Op erating P ressur e (p.1221 ) for details . This option app ears only f or time-dep enden t compr essible flo ws. Operating P ressur e sets the op erating pr essur e for the pr oblem. For all flo ws, ANSY S Fluen t uses gauge pr essur e internally . Any time an absolut e pr essur e is needed , it is gener ated b y adding the op erating pr essur e to the r el- ative pr essur e. See Operating P ressur e (p.1152 ) for a detailed descr iption of op erating pr essur e and how to set it. Referenc e Pressur e Location sets the lo cation of the c ell whose pr essur e value is used t o adjust the gauge pr essur e field f or inc om- pressible flo ws tha t do not in volve an y pr essur e boundar ies. See Reference Pressur e Location (p.1154 ) for details . Real G as S tate allows you t o sp ecify the op erating c onditions in the sub critical regime of y our mo del. Note tha t if the operating c onditions in y our mo del ar e en tirely in the sup ercritical regime , this setting will ha ve no eff ect. Note This option app ears only when a C ubic E qua tion of S tate Real G as mo del is chosen. 3471Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Cell Z one C onditions Task P ageVapor is the default option, and ther efore assumes tha t the r eal gas sta te is v apor. Liquid assumes tha t the r eal gas sta te is liquid . Gravity contains inputs f or gr avitational acc eleration, the B oussinesq mo del, and v ariable densit y. Gravity enables the sp ecific ation of gr avity. Gravita tional A cceler ation sets the , , and comp onen ts of the gr avitational acc eleration v ector. (The comp onen t is a vailable only in 3D solv ers.) See Natural Convection and B uoyancy-Driven F lows (p.1476 ) for details ab out buo yancy-dr iven flo ws.This option app ears only when Gravity is enabled . Boussinesq P aramet ers contains inputs r elated t o the B oussinesq mo del. This option app ears only if Energy (in the Ener gy Dialog Box (p.3252 )) and Gravity are enabled . See The B oussinesq M odel (p.1476 ) for mor e inf ormation on the B oussinesq mo del. Operating Temp erature sets the op erating t emp erature ( in Equa tion 13.3 (p.1477 )) for use with the B oussinesq appr ox- imation. Variable-D ensit y Paramet ers contains inputs r elated t o the mo deling of v ariable densit y.This option app ears only when Gravity is enabled . Specified Op erating D ensit y enables the sp ecific ation of op erating densit y. See Operating D ensit y (p.1479 ) for details . Operating D ensit y sets the op erating densit y ( in Equa tion 13.4 (p.1479 )).This par amet er can b e set only when Specified Op erating D ensit y is enabled . 47.7.5. Selec t Input P aramet er D ialo g Box The Selec t Input P aramet er dialo g box allo ws you t o cho ose fr om a listing of e xisting input par amet ers as w ell as t o cr eate and define new input par amet ers. For mor e inf ormation ab out par amet ers, see Defining and Viewing P aramet ers (p.842) in the U ser's G uide , and see Working With Input and Output Paramet ers in Workbench in the ANSY S Fluen t in Workbench U ser's G uide . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3472Task P age R eference GuideControls Paramet ers contains a list of e xisting c ompa tible input par amet ers Current Value displa ys the v alue of the cur rently selec ted par amet er. Used In lists an y variables tha t are alr eady asso ciated with the cur rently selec ted par amet er. Use C onstan t allows you t o change the asso ciated par amet er to a c onstan t (tha t is, real) v alue . New P aramet er opens the Paramet er Expr ession D ialog Box (p.3742 ), in which y ou c an assign names and v alues t o an input paramet er. 47.7.6. Profiles D ialo g Box The Profiles dialo g box allo ws you t o define new pr ofiles b y reading c ell z one and b oundar y pr ofile files .You c an also e xamine the e xisting pr ofile definitions and delet e unused pr ofiles . See Profiles (p.1051 ) for details ab out c ell z one and b oundar y pr ofiles . 3473Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Cell Z one C onditions Task P ageControls Profile contains a selec table list of a vailable pr ofiles .When a pr ofile is selec ted its a vailable fields ar e displa yed under Fields . Fields displa ys the fields a vailable in the selec ted pr ofile . After the pr ofile file has b een r ead, these fields will also app ear in an y boundar y condition dialo g box (for e xample , the Velocity Inlet dialo g box) tha t allo ws profile sp ecific ation of a v ariable .To the r ight of (or b elow) the v ariable in the b oundar y conditions dialo g box, ther e will b e a dr op-do wn list tha t contains a constan t and the fields fr om a vailable pr ofile files .To use a par ticular pr ofile field , just selec t it fr om the list. Interpolation M etho d allows you t o selec t the in terpolation metho d for the pr ofile selec ted fr om the Profile list. This selec tion is only a vailable f or p oint profiles , and will only tak e eff ect when the Apply butt on is click ed.The choic es include the f ollowing: Constan t specifies tha t ANSY S Fluen t should use z eroth-or der in terpolation t o assign the p oint profile v alues to the near est c ell fac es a t the b oundar y.This is the default selec tion. Inverse D istanc e specifies tha t ANSY S Fluen t should assign a v alue t o each c ell fac e at the b oundar y based on w eigh ted contributions fr om the v alues in the p oint profile file .The w eigh ting fac tor is in versely pr oportional to the distanc e between the pr ofile p oint and the c ell fac e center. Least S quar es specifies tha t ANSY S Fluen t should assign v alues t o the c ell fac es a t the b oundar y thr ough a first-or der interpolation metho d tha t tries t o minimiz es the sum of the squar es of the off sets (r esiduals) b etween the pr ofile da ta p oints and the c ell fac e centers. Referenc e Frame allows you t o attach the pr ofile t o a r eference frame . If you selec t a r eference frame other than global , then the pr ofile will f ollow the or ientation and/or motion of the sp ecified r eference frame . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3474Task P age R eference GuideDelet e delet es the selec ted pr ofile fr om memor y. Replic ate... opens the Replic ate Profile D ialog Box (p.3475 ), in which y ou c an r eorient and sc ale the pr ofile .This it em app ears only in 3D . Orient... opens the Orient Profile D ialog Box (p.3476 ), in which y ou c an r eorient and sc ale the pr ofile .This it em app ears only in 3D . Read ... opens The S elec t File D ialog Box (p.569) so tha t you c an r ead a b oundar y pr ofile file . If a pr ofile in the file has the same name as an e xisting pr ofile , the old pr ofile will b e overwritten. Write... opens the Write Profile D ialog Box (p.3478 ), in which y ou c an sa ve pr ofile da ta. Apply sets the selec tion made in the Interpolation M etho d list f or p oint profiles in pr epar ation f or in terpolation. The pr ofile is not ac tually in terpolated un til a pr ofile field is selec ted in a b oundar y condition dialo g box (for e xample , the Velocity Inlet dialo g box) and the solution is initializ ed. 47.7.7. Replic ate Profile D ialo g Box The Replic ate Profile dialo g box allo ws you t o replic ate a pr ofile p eriodically, typic ally f or use as a boundar y condition in a turb omachinar y case. See Replic ating P rofiles (p.1064 ) for details . 3475Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Cell Z one C onditions Task P ageControls Current pr ofile shows the name of the cur rently selec ted pr ofile in the Profiles D ialog Box (p.3473 ).This is the pr ofile on which the new pr ofile will b e based . New P rofile sets the name of the new c ell z one or b oundar y pr ofile . New Field D efinitions contains inputs and c ontrols f or the definition of the v ector and sc alar fields in the new pr ofile . New Fields sets the numb er of da ta fields in the new pr ofile . New Field N ames contains inputs f or the names of the da ta fields in the new pr ofile . For a v ector field , all 3 inputs in each r ow will b e ac tive; for a sc alar field , only the first will b e ac tive. Comput e From... contains dr op-do wn lists with the names of the fields in the Current pr ofile . In these lists , selec t the fields fr om which the New Field N ames will b e comput ed. Treat as Sc alar Q uan tity indic ates (if on) tha t the adjac ent field is a sc alar quan tity. If this option is off , the field is a v ector quan tity. Current Profile D efinitions contains inputs f or the r eplic ation of the new pr ofile . Full 360 deg . automa tically det ermines the numb er of c opies of the or iginal pr ofile tha t are needed t o mak e the full 360 degr ee pr ofile based on the other inf ormation y ou sp ecify Numb er of c opies specifies ho w man y copies of the or iginal pr ofile ar e created. Numb er of sec tors in 360 deg . the numb er of p eriodic sec tions , based on the or iginal pr ofile , tha t are pr esen t in 360 degr ees. Numb er of sec tors in pr ofile the numb er of p eriodic sec tions in the or iginal pr ofile . Calcula ted angle (for displa y only) the angle o ccupied b y the or iginal pr ofile . Create creates a new pr ofile using the inf ormation sp ecified in the dialo g box. 47.7.8. Orient Profile D ialo g Box The Orient Profile dialo g box allo ws you t o reorient a pr ofile so tha t you c an apply it t o a par ticular boundar y. See Reorienting P rofiles (p.1059 ) for details . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3476Task P age R eference GuideControls Current pr ofile shows the name of the cur rently selec ted pr ofile in the Profiles D ialog Box (p.3473 ).This is the pr ofile on which the new pr ofile will b e based . New P rofile sets the name of the new c ell z one or b oundar y pr ofile . New Field D efinitions contains inputs and c ontrols f or the definition of the v ector and sc alar fields in the new pr ofile . New Fields sets the numb er of da ta fields in the new pr ofile . New Field N ames contains inputs f or the names of the da ta fields in the new pr ofile . For a v ector field , all 3 inputs in each r ow will b e ac tive; for a sc alar field , only the first will b e ac tive. Comput e From... contains dr op-do wn lists with the names of the fields in the Current pr ofile . In these lists , selec t the fields fr om which the New Field N ames will b e comput ed. Treat as Sc alar Q uan tity indic ates (if on) tha t the adjac ent field is a sc alar quan tity. If this option is off , the field is a v ector quan tity. 3477Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Cell Z one C onditions Task P ageOrient To... contains inputs f or the definition of the lo cal coordina te sy stem f or the new pr ofile .This c oordina te sy stem will det ermine the or ientation of the pr ofile . Direction Vector is the v ector tha t transla tes a c ell z one or b oundar y pr ofile t o the new p osition, and is defined b etween the c enters of the pr ofile fields . Rota tion M atrix [RM ] specifies the r otational ma trix , which is based on E uler angles ( , , and ) tha t define an or tho- gonal sy stem as the r esult of the thr ee succ essiv e rotations fr om the or iginal sy stem . See Reorienting P rofiles (p.1059 ) for mor e inf ormation. Create creates a new pr ofile using the inf ormation sp ecified in the dialo g box. 47.7.9. Write Profile D ialo g Box The Write Profile dialo g box allo ws you t o cr eate a pr ofile file fr om the c onditions on a sp ecified c ell zone or b oundar y/sur face. See Writing P rofile F iles (p.594) for details on wr iting pr ofile files . Controls Options contains options f or wr iting pr ofiles . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3478Task P age R eference GuideDefine N ew P rofiles enables the cr eation of a pr ofile file fr om the c onditions on a sp ecified b oundar y or sur face. Write Currently D efined P rofiles enables the cr eation of a pr ofile file c ontaining all pr ofiles tha t are cur rently defined . Merge P rofile Options Write M erge P rofiles (only a vailable if t wo or mor e sur faces ar e selec ted) wr ites a .csv file with the selec ted sur faces consolida ted in to one set of da ta p oints. Surfaces contains a list fr om which y ou c an selec t the sur face(s) fr om which y ou w ant to extract da ta. Values contains a list fr om which y ou c an selec t the v ariable(s) f or which y ou w ant to create pr ofiles . Write... opens The S elec t File D ialog Box (p.569), in which y ou c an sp ecify a filename f or the pr ofile file . 47.8. Boundar y Conditions Task P age The Boundar y Conditions task page allo ws you t o set the t ype of a b oundar y and displa y other dialo g boxes to set the b oundar y condition par amet ers f or each b oundar y. 3479Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions Task P ageControls Zone contains a selec table list of b oundar y zones fr om which y ou c an selec t the z one of in terest.You c an check a zone t ype by using the mouse pr obe (see Controlling the M ouse B utton F unctions (p.2833 )) on the displa yed physical mesh. This f eature is par ticular ly hand y if y ou ar e setting up a pr oblem f or the first time , or if y ou have two or mor e boundar y zones of the same t ype and y ou w ant to det ermine the z one IDs .To do this you must first displa y the mesh with the Mesh D ispla y Dialog Box (p.3239 ).Then click the b oundar y zone with the r ight (selec t) mouse butt on. ANSY S Fluen t will pr int the z one ID and t ype of tha t boundar y zone in the c onsole windo w. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3480Task P age R eference GuidePhase specifies the phase f or which c onditions a t the selec ted b oundar y Zone are being set. This it em app ears if the VOF, mix ture, or E uler ian multiphase mo del is b eing used . See Defining M ultiphase C ell Z one and Boundar y Conditions (p.2124 ) for details . Type contains a dr op-do wn list of b oundar y condition t ypes for the selec ted z one .The list c ontains all p ossible types to which the z one c an b e changed . Imp ortant Note tha t you c annot use this metho d to change z one t ypes to or fr om the p eriodic t ype, sinc e additional r estrictions e xist f or this b oundar y type.Creating P eriodic Z ones and Interfaces (p.811) explains ho w to cr eate and unc ouple p eriodic z ones . ID displa ys the z one ID numb er of the selec ted z one . (This is f or inf ormational pur poses only ; you c annot edit this numb er.) Edit... opens the appr opriate dialo g box for setting the b oundar y conditions f or tha t par ticular b oundar y type. Copy... opens the Copy Conditions D ialog Box (p.3469 ), which allo ws you t o copy boundar y conditions fr om one zone t o other z ones of the same t ype. See Copying C ell Z one and B oundar y Conditions (p.840) for details . Profiles ... opens the Profiles D ialog Box (p.3473 ). Paramet ers... opens the Paramet ers D ialog Box (p.3738 ). Operating C onditions ... opens the Operating C onditions D ialog Box (p.3470 ). Displa y M esh... opens the Mesh D ispla y Dialog Box (p.3239 ). Periodic C onditions ... opens the Periodic C onditions D ialog Box (p.3564 ). Highligh t Zone when enabled highligh ts the b oundar y zone (selec ted in the task page) in the gr aphics windo w. For additional inf ormation, see the f ollowing sec tions: 47.8.1. Axis D ialog Box 47.8.2. Degassing D ialog Box 47.8.3. Exhaust F an D ialog Box 47.8.4. Fan D ialog Box 47.8.5. Inlet Vent Dialog Box 47.8.6. Intake Fan D ialog Box 47.8.7. Interface Dialog Box 47.8.8. Interior D ialog Box 3481Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions Task P age47.8.9. Mass-F low Inlet D ialog Box 47.8.10. Mass-F low Outlet D ialog Box 47.8.11. Outflo w D ialog Box 47.8.12. Outlet Vent Dialog Box 47.8.13. Periodic D ialog Box 47.8.14. Porous J ump D ialog Box 47.8.15. Pressur e Far-Field D ialog Box 47.8.16. Pressur e Inlet D ialog Box 47.8.17. Pressur e Outlet D ialog Box 47.8.18. Radia tor D ialog Box 47.8.19. RANS/LES In terface Dialog Box 47.8.20. Symmetr y Dialog Box 47.8.21. Velocity Inlet D ialog Box 47.8.22. Wall D ialog Box 47.8.23. Periodic C onditions D ialog Box 47.8.1. Axis D ialo g Box The Axis dialo g box can b e used t o mo dify the name of an axis z one; ther e ar e no c onditions t o be set. It is op ened fr om the Boundar y Conditions Task P age (p.3479 ). See Axis B oundar y Conditions (p.1002 ) for inf ormation ab out axis b oundar ies. Controls Zone N ame sets the name of the z one . Phase displa ys the name of the phase .This it em app ears if the VOF, mix ture, or E uler ian multiphase mo del is being used . 47.8.2. Degassing D ialo g Box The Degassing dialo g box can b e used t o mo dify the name of a degassing z one; ther e ar e no c onditions to be set. It is op ened fr om the Boundar y Conditions Task P age (p.3479 ). See Degassing B oundar y Conditions (p.970) for inf ormation ab out axis b oundar ies. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3482Task P age R eference GuideControls Zone N ame sets the name of the z one . Phase displa ys the name of the phase . 47.8.3. Exhaust F an D ialo g Box The Exhaust F an dialo g box sets the b oundar y conditions f or an e xhaust fan z one . It is op ened fr om the Boundar y Conditions Task P age (p.3479 ). See Inputs a t Exhaust F an B oundar ies (p.969) for details about defining the it ems b elow. Controls Zone N ame sets the name of the z one . Phase displa ys the name of the phase . It app ears only f or multiphase flo ws. 3483Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions Task P ageMomen tum contains the momen tum par amet ers. Backflo w Ref erenc e Frame specify whether backflo w temp erature, pressur e, and flo w dir ections ar e in the Absolut e or Rela tive to the A djac ent Cell Z one reference frame . Gauge P ressur e sets the gauge pr essur e at the outlet b oundar y. Backflo w D irection S pecific ation M etho d sets the dir ection of the inflo w str eam should the flo w reverse dir ection. You c an cho ose Direction Vector,Normal t o Boundar y,or From N eighb oring C ell. Coordina te System contains a dr op-do wn list f or selec ting the c oordina te sy stem. You c an cho ose Cartesian ,Cylindr ical, or Local C ylindr ical.This option is a vailable only when Direction Vector is selec ted fr om the Backflo w Direction S pecific ation M etho d drop-do wn list. X-,Y-, Z-C omp onen t of F low D irection allows you t o sp ecify the v elocity comp onen ts in x, y, and z dir ections r espectively.This option is available when Cartesian is selec ted f or the Coordina te System. Radial-, Tangen tial-, Axial-C omp onen t of F low D irection set the dir ection of the flo w at the b oundar y.These it ems will app ear f or 2D axisymmetr ic cases , or for 3D c ases f or which the selec ted Coordina te System is Cylindr ical or Local C ylindr ical. Backflo w P ressur e Specific ation specifies ho w the pr essur e is c alcula ted under backflo w conditions . If you selec t Static P ressur e, the Gauge P ressur e is dir ectly imp osed as the b oundar y fac e pr essur e; if you selec t Total P ressur e, the Gauge P ressur e will b e combined with a d ynamic c ontribution tha t is based on the v elocity in the adjac ent cell z one . Pressur e Jump specifies the r ise in pr essur e acr oss the fan. See Specifying the P ressur e Jump (p.970) for details . Axis Or igin sets the X,Y, and Z coordina tes of the or igin of the lo cal cylindr ical coordina te sy stem. Axis D irection sets the X,Y, and Z comp onen ts of the dir ection of the lo cal cylindr ical coordina te sy stem. Turbulenc e displa ys the turbulenc e par amet ers. Specific ation M etho d specifies which metho d will b e used t o define the turbulenc e par amet ers.You c an cho ose K and Epsilon ( - mo dels and RSM only), K and Omega ( - mo dels only), Intensit y and L ength Scale,Intensit y and Visc osit y Ratio,Intensit y and H ydraulic D iamet er,Modified Turbulen t Visc osit y (Spalar t-Allmar as mo del only), or Turbulen t Visc osit y Ratio (Spalar t-Allmar as mo del only). See Determining Turbulenc e Paramet ers (p.914) for inf ormation ab out the inputs f or each of these metho ds. (This it em will app ear only f or turbulen t flo w calcula tions .) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3484Task P age R eference GuideBackflo w Turbulen t Kinetic E nergy, Backflo w Turbulen t Dissipa tion R ate set v alues f or the turbulenc e kinetic ener gy and its dissipa tion r ate .These it ems will app ear if you cho ose K and E psilon as the Specific ation M etho d. Backflo w Turbulen t Kinetic E nergy, Backflo w S pecific ation D issipa tion R ate set v alues f or the turbulenc e kinetic ener gy and its sp ecific dissipa tion r ate .These it ems will app ear if y ou cho ose K and Omega as the Specific ation M etho d. Backflo w Turbulen t Intensit y, Backflo w Turbulen t Length Sc ale set v alues f or turbulenc e intensit y and turbulenc e length sc ale .These it ems will app ear if y ou choose Intensit y and L ength Sc ale as the Specific ation M etho d. Backflo w Turbulen t Intensit y, Backflo w Turbulen t Visc osit y Ratio set v alues f or turbulenc e intensit y and turbulen t visc osity ratio .These it ems will app ear if you cho ose Intensit y and Visc osit y Ratio as the Specific ation M etho d. Backflo w Turbulen t Intensit y, Backflo w H ydraulic D iamet er set v alues f or turbulenc e intensit y and h ydraulic diamet er .These it ems will app ear if y ou choose Intensit y and H ydraulic D iamet er as the Specific ation M etho d. Backflo w M odified Turbulen t Visc osit y sets the v alue of the backflo w mo dified turbulen t visc osity .This it em will app ear if y ou cho ose Modified Turbulen t Visc osit y as the Specific ation M etho d. Backflo w Turbulen t Visc osit y Ratio sets the v alue of the backflo w turbulen t visc osity ratio .This it em will app ear if y ou cho ose Turbulen t Visc osit y Ratio as the Specific ation M etho d. Reynolds-S tress S pecific ation M etho d specifies which metho d will b e used t o det ermine the backflo w Reynolds str ess b oundar y condi- tions when the R eynolds str ess turbulenc e mo del is used .You c an cho ose either K or Turbulenc e Intensit y or Reynolds-S tress C omp onen ts. If you cho ose the f ormer , ANSY S Fluen t will c omput e the R eynolds str esses f or y ou. If you cho ose the la tter, you will e xplicitly sp ecify the R eynolds stresses y ourself . See Reynolds S tress M odel (p.1449 ) for details . (This it em will app ear only f or RSM turbulen t flo w calcula tions .) Backflo w UU, VV,WW , UV,VW, UW Re ynolds S tresses specify the backflo w Reynolds str ess c omp onen ts when Reynolds-S tress C omp onen ts is chosen as the Reynolds-S tress S pecific ation M etho d. Thermal contains the ther mal par amet ers.This par amet er is a vailable only when the ener gy equa tion is tur ned on. Backflo w Total Temp erature sets the t otal t emp erature of the inflo w str eam should the flo w reverse dir ection. Radia tion contains the b oundar y conditions f or the r adia tion mo del a t the e xhaust fan. External Black B ody Temp erature M etho d, Internal E missivit y set the r adia tion b oundar y conditions when y ou ar e using the P-1, DTRM, DO, S2S, or MC mo dels f or radia tion hea t transf er. See Defining B oundar y Conditions f or R adia tion (p.1514 ) for details . 3485Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions Task P ageParticipa tes in S olar R ay Tracing specifies whether or not the fan par ticipa tes in solar r ay tracing . Solar Transmissivit y Factor specifies a multiplier (r anging fr om 0 t o 1) tha t is applied t o the solar ir radia tion en tering the domain through the fan. Participa tes in View Factor C alcula tion specifies whether or not the fan par ticipa tes in the view fac tor calcula tion as par t of the S2S r adia tion model. This par amet er is a vailable only if y ou selec t the Surface to Surface radia tion mo del. Species contains the sp ecies par amet ers. Specify S pecies in M ole F ractions allows you t o sp ecify the sp ecies in mole fr actions r ather than mass fr actions . Mean M ixture Fraction, Mixture Fraction Varianc e set inlet v alues f or the PDF mix ture fraction and its v arianc e. (These it ems will app ear only if y ou ar e using the non-pr emix ed or par tially pr emix ed c ombustion mo del.) Secondar y M ean M ixture Fraction, Secondar y M ixture Fraction Varianc e set inlet v alues f or the sec ondar y mix ture fraction and its v arianc e. (These it ems will app ear only if you ar e using the non-pr emix ed or par tially pr emix ed c ombustion mo del with t wo mix ture fractions .) Species M ass F ractions contains inputs f or the mass fr actions of defined sp ecies . See Defining C ell Z one and B oundar y Con- ditions f or S pecies (p.1649 ) for details ab out these inputs .These it ems will app ear only if y ou ar e modeling non-r eacting multi-sp ecies flo w or y ou ar e using the finit e-rate reaction f ormula tion. Backflo w P rogress Variable sets the v alue of the pr ogress v ariable f or pr emix ed turbulen t combustion. See Setting B oundar y Conditions f or the P rogress Variable (p.1754 ) for details . This it em will app ear only if the pr emix ed or par tially pr emix ed c ombustion mo del is used . DPM contains the discr ete phase par amet ers.This tab is a vailable only if y ou ha ve defined a t least one injec tion. Discr ete Phase BC Type sets the w ay tha t the discr ete phase b ehaves with r espect to the b oundar y.This it em app ears when one or mor e injec tions ha ve been defined . reflec t rebounds the par ticle off the b oundar y with a change in its momen tum as defined b y the c oefficien t of restitution (see Particle R eflec tion a t Wall in the Fluent Theor y Guide ). trap termina tes the tr ajec tory calcula tions and r ecords the fa te of the par ticle as “trapp ed”. In the c ase of e vaporating dr oplets , their en tire mass instan taneously passes in to the v apor phase and en ters the c ell adjac ent to the b oundar y. See Figur e 24.25: “Trap” Boundar y Condition f or the D iscrete Phase (p.1988 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3486Task P age R eference Guideescape reports the par ticle as ha ving “escaped” when it enc oun ters the b oundar y.Trajec tory calcula tions are termina ted. See Figur e 24.26: “Escape” Boundar y Condition f or the D iscrete Phase (p.1988 ). wall-jet indic ates tha t the dir ection and v elocity of the dr oplet par ticles ar e giv en b y the r esulting mo- men tum flux, which is a func tion of the impingemen t angle . See Figur e 16.6: “Wall Jet” Boundar y Condition f or the D iscrete Phase in the Theor y Guide . user-defined specifies a user-defined func tion t o define the discr ete phase b oundar y condition t ype. Discr ete Phase BC F unc tion sets the user-defined func tion fr om the dr op-do wn list. Multiphase contains the multiphase par amet ers. Backflo w G ranular Temp erature specifies t emp erature for the solids phase and is pr oportional t o the k inetic ener gy of the r andom motion of the par ticles . Volume F raction S pecific ation M etho d sets the metho d used t o sp ecify the v olume fr action of the sec ondar y phase selec ted in the Boundar y Conditions Task P age (p.3479 ).This sec tion of the dialo g box will app ear when one of the multiphase models is b eing used . See Defining M ultiphase C ell Z one and B oundar y Conditions (p.2124 ) for details . Backflo w Volume F raction specifies the v olume fr action of the sec ondar y phase as a c onstan t, profile , of UDF func tion. From N eighb oring C ell calcula tes the v olume fr action fr om the neighb oring c ells. Potential displa ys the b oundar y conditions f or the elec tric potential field .This tab is a vailable only if y ou ha ve enabled either the Electric P otential mo del or the Electrochemic al reaction mo del in the Species D ialog Box (p.3417 ). Potential B oundar y Condition is a dr op-do wn list of a vailable p otential b oundar y condition t ypes:Specified F lux and Specified Value . For the Specified F lux boundar y condition, you will need t o sp ecify Current Densit y at the wall. For the Specified Value boundar y condition, you will need t o sp ecify Potential at the w all. UDS contains the UDS par amet ers. User-D efined Sc alar B oundar y Condition app ears only if user-defined sc alars ar e sp ecified . User Sc alar n specifies whether the sc alar is a sp ecified flux or a sp ecified v alue . User-D efined Sc alar B oundar y Value app ears only if user-defined sc alars ar e sp ecified . 3487Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions Task P ageUser Sc alar n specifies the v alue of the sc alar. 47.8.4. Fan D ialo g Box The Fan dialo g box sets the b oundar y conditions f or a fan z one . It is op ened fr om the Boundar y Conditions Task P age (p.3479 ). See User Inputs f or F ans (p.1004 ) for details ab out the it ems b elow. Controls Zone N ame sets the name of the z one . Pressur e-Jump S pecific ation contains inputs tha t define the pr essur e jump acr oss the fan. Reverse F an D irection sets the fan flo w dir ection r elative to the z one dir ection. If Zone A verage D irection is p ointing in the direction y ou w ant the fan t o blo w, do not selec t Reverse F low; if it is p ointing in the opp osite dir ection, selec t Reverse F low. Zone A verage D irection displa ys the (fac e-averaged) dir ection v ector for the z one as an aid in det ermining whether or not you w ant to selec t Reverse F low. Profile S pecific ation of P ressur e-Jump enables the use of a b oundar y pr ofile or user-defined func tion f or the pr essur e jump sp ecific ation. See Profiles (p.1051 ) or the Fluen t Customiza tion M anual for details .When this option is enabled , Pressur e Jump P rofile will app ear in the dialo g box and the ne xt four it ems b elow it will not. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3488Task P age R eference GuidePressur e Jump P rofile contains a dr op-do wn list fr om which y ou c an selec t a b oundar y pr ofile or a user-defined func tion for the pr essur e jump definition. This it em will app ear if y ou enable Profile S pecific ation of P ressur e- Jump . Pressur e-Jump specifies the pr essur e-jump as a c onstan t value or as a p olynomial, piec ewise-linear , or piec ewise- polynomial func tion of v elocity. See Defining the P ressur e Jump (p.1005 ) for details . Limit P olynomial Velocity Range limits the minimum and maximum v elocity magnitudes used t o calcula te the pr essur e jump when it is defined as a func tion of v elocity. Min Velocity M agnitude , Max Velocity M agnitude specify the minimum and maximum v alues t o which the v elocity magnitude is limit ed (when the Limit P olynomial Velocity Range option is enabled). Calcula te Pressur e-Jump fr om A verage C onditions enables the option t o use the mass-a veraged v elocity nor mal t o the fan t o det ermine a single pr essur e- jump v alue f or all fac es in the fan z one . Discr ete Phase BC Type sets the w ay tha t the discr ete phase b ehaves with r espect to the b oundar y.This it em app ears when one or mor e injec tions ha ve been defined . interior allows the par ticles t o pass thr ough the b oundar y. reflec t rebounds the par ticle off the b oundar y with a change in its momen tum as defined b y the c oefficien t of restitution. (See Particle R eflec tion a t Wall in the Fluent Theor y Guide .) trap termina tes the tr ajec tory calcula tions and r ecords the fa te of the par ticle as “trapp ed”. In the c ase of e vaporating dr oplets , their en tire mass instan taneously passes in to the v apor phase and en ters the c ell adjac ent to the b oundar y. See Figur e 24.25: “Trap” Boundar y Condition f or the D iscrete Phase (p.1988 ). escape reports the par ticle as ha ving “escaped” when it enc oun ters the b oundar y.Trajec tory calcula tions are termina ted. See Figur e 24.26: “Escape” Boundar y Condition f or the D iscrete Phase (p.1988 ). wall-jet indic ates tha t the dir ection and v elocity of the dr oplet par ticles ar e giv en b y the r esulting mo- men tum flux, which is a func tion of the impingemen t angle . See Figur e 16.6: “Wall Jet” Boundar y Condition f or the D iscrete Phase in the Theor y Guide . user-defined specifies a user-defined func tion t o define the discr ete phase b oundar y condition t ype. Discr ete Phase BC F unc tion sets the user-defined func tion fr om the dr op-do wn list. 3489Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions Task P ageSwirl-Velocity Specific ation contains inputs f or the sp ecific ation of fan swir l velocity.This sec tion of the dialo g box app ears only f or 3D mo dels . Swirl-Velocity Specific ation enables the sp ecific ation of a swir l velocity for the fan. Fan A xis sets the dir ection v ector for the fan ’s axis of r otation. Fan Or igin sets the or igin in the global c oordina te sy stem thr ough which the fan r otation axis passes . Fan Hub R adius set the r adius of the hub .The default is 1e-6 t o avoid division b y zero in the p olynomial. Profile S pecific ation of Tangen tial Velocity enables the use of a b oundar y pr ofile or user-defined func tion f or the tangen tial v elocity sp ecific ation. See Profiles (p.1051 ) or the Fluen t Customiza tion M anual for details .When this option is enabled , Tangen tial Velocity Profile will app ear in the dialo g box and Tangen tial-V elocity Polynomial Coefficien ts will not. Tangen tial Velocity Profile contains a dr op-do wn list fr om which y ou c an selec t a b oundar y pr ofile or a user-defined func tion for the definition of the tangen tial v elocity.This it em will app ear if y ou enable Profile S pecific ation of Tangen tial Velocity. Tangen tial-V elocity Polynomial C oefficien ts sets the c oefficien ts for the tangen tial v elocity polynomial. Separ ate the c oefficien ts by spac es. Profile S pecific ation of R adial Velocity enables the use of a b oundar y pr ofile or user-defined func tion f or the r adial v elocity sp ecific ation. See Profiles (p.1051 ) or the Fluen t Customiza tion M anual for details .When this option is enabled ,Ra- dial Velocity Profile will app ear in the dialo g box and Radial-V elocity Polynomial C oefficien ts will not. Radial Velocity Profile contains a dr op-do wn list fr om which y ou c an selec t a b oundar y pr ofile or a user-defined func tion for the definition of the r adial v elocity.This it em will app ear if y ou enable Profile S pecific ation of Radial Velocity. Radial-V elocity Polynomial C oefficien ts sets the c oefficien ts for the r adial v elocity polynomial. Separ ate the c oefficien ts by spac es. 47.8.5. Inlet Vent Dialo g Box The Inlet Vent dialo g box sets the b oundar y conditions f or an inlet v ent zone . It is op ened fr om the Boundar y Conditions Task P age (p.3479 ). See Inputs a t Inlet Vent Boundar ies (p.947) for details ab out defining the it ems b elow. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3490Task P age R eference GuideControls Zone N ame sets the name of the z one . Momen tum contains the momen tum par amet ers. Referenc e Frame specifies the r eference frame f or the inlet v ent. If the c ell z one adjac ent to the inlet v ent is mo ving , you c an cho ose t o sp ecify r elative or absolut e velocities b y selec ting Rela tive to Adjac ent Cell Z one or Absolut e in the Referenc e Frame drop-do wn list. Gauge Total P ressur e sets the gauge t otal (or stagna tion) pr essur e of the inflo w str eam. If you ar e using mo ving r eference frames , see Defining Total P ressur e and Temp erature (p.922) for inf ormation ab out r elative and absolut e total pr essur e. Supersonic/Initial G auge P ressur e sets the sta tic pr essur e on the b oundar y when the flo w becomes (lo cally) sup ersonic . It is also used to comput e initial v alues f or pr essur e, temp erature, and v elocity if the inlet v ent boundar y condition is selec ted f or computing initial v alues (see Initializing the En tire Flow Field U sing S tandar d Initializa- tion (p.2605 )). 3491Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions Task P ageDirection S pecific ation M etho d specifies the metho d you will use t o define the flo w dir ection. If you cho ose Direction Vector, you will define the flo w dir ection c omp onen ts, and if y ou cho ose Normal t o Boundar y no inputs ar e re- quir ed. See Defining the F low D irection (p.923) for inf ormation on sp ecifying flo w dir ection. Coordina te System specifies whether Cartesian ,Cylindr ical,Local C ylindr ical,Local C ylindr ical S wirl vector comp onen ts will b e sp ecified .This it em will app ear only f or 3D c ases in which y ou ha ve selec ted Direction Vector as the Direction S pecific ation M etho d. X,Y,Z-C omp onen t of F low D irection set the dir ection of the flo w at the inlet b oundar y.These it ems will app ear if the selec ted Coordina te System is Cartesian or the mo del is 2D non-axisymmetr ic. Radial, Tangen tial, Axial C omp onen t of F low D irection set the dir ection of the flo w at the inlet b oundar y.These it ems will app ear f or 2D axisymmetr ic cases , or for 3D c ases f or which the selec ted Coordina te System is Cylindr ical or Local C ylindr ical. Axis Or igin sets the X,Y, and Z coordina tes of the or igin of the lo cal cylindr ical coordina te sy stem. Axis D irection sets the X,Y, and Z comp onen ts of the dir ection of the lo cal cylindr ical coordina te sy stem. Loss-C oefficien t sets the non-dimensional loss c oefficien t used t o comput e the pr essur e dr op. See Specifying the L oss Coefficien t (p.948) for details . Turbulenc e lists the turbulenc e par amet ers. Specific ation M etho d specifies which metho d will b e used t o define the turbulenc e par amet ers.You c an cho ose K and Epsilon ( - mo dels and RSM only), K and Omega ( - mo dels only), Intensit y and L ength Scale,Intensit y and Visc osit y Ratio,Intensit y and H ydraulic D iamet er,Modified Turbulen t Visc osit y (Spalar t-Allmar as mo del only), or Turbulen t Visc osit y Ratio (Spalar t-Allmar as mo del only). See Determining Turbulenc e Paramet ers (p.914) for inf ormation ab out the inputs f or each of these metho ds. (This it em will app ear only f or turbulen t flo w calcula tions .) Turbulen t Kinetic E nergy,Turbulen t Dissipa tion R ate set v alues f or the turbulenc e kinetic ener gy and its dissipa tion r ate .These it ems will app ear if you cho ose K and E psilon as the Specific ation M etho d. Turbulen t Kinetic E nergy, Specific D issipa tion R ate set v alues f or the turbulenc e kinetic ener gy and its sp ecific dissipa tion r ate .These it ems will app ear if y ou cho ose K and Omega as the Specific ation M etho d. Turbulenc e In tensit y,Turbulenc e Length Sc ale set v alues f or turbulenc e intensit y and turbulenc e length sc ale .These it ems will app ear if y ou choose Intensit y and L ength Sc ale as the Specific ation M etho d. Turbulenc e In tensit y,Turbulen t Visc osit y Ratio set v alues f or turbulenc e intensit y and turbulen t visc osity ratio .These it ems will app ear if you cho ose Intensit y and Visc osit y Ratio as the Specific ation M etho d. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3492Task P age R eference GuideTurbulenc e In tensit y, Hydraulic D iamet er set v alues f or turbulenc e intensit y and h ydraulic diamet er .These it ems will app ear if y ou choose Intensit y and H ydraulic D iamet er as the Specific ation M etho d. Modified Turbulen t Visc osit y sets the v alue of the mo dified turbulen t visc osity .This it em will app ear if y ou cho ose Modified Turbulen t Visc osit y as the Specific ation M etho d. Turbulen t Visc osit y Ratio sets the v alue of the turbulen t visc osity ratio .This it em will app ear if y ou cho ose Turbulen t Visc osit y Ratio as the Specific ation M etho d. Reynolds-S tress S pecific ation M etho d specifies which metho d will b e used t o det ermine the R eynolds str ess b oundar y conditions when the R eynolds str ess turbulenc e mo del is used .You c an cho ose either K or Turbulenc e In tensit y or Reynolds-S tress C omp onen ts. If you cho ose the f ormer , ANSY S Fluen t will c omput e the Reynolds str esses f or y ou. If you cho ose the la tter, you will e xplicitly sp ecify the R eynolds str esses yourself . See Reynolds S tress M odel (p.1449 ) for details . (This it em will app ear only f or RSM turbulen t flow calcula tions .) UU, VV,WW , UV,VW, UW Re ynolds S tresses specify the R eynolds str ess c omp onen ts when Reynolds-S tress C omp onen ts is chosen as the Reynolds-S tress S pecific ation M etho d. Thermal contains the ther mal par amet ers. Total Temp erature sets the t otal t emp erature of the inflo w str eam. If you ar e using mo ving r eference frames , see Defining Total P ressur e and Temp erature (p.922) for inf ormation ab out r elative and absolut e total t emp erature. Radia tion contains the r adia tion par amet ers. External Black B ody Temp erature M etho d, Internal E missivit y set the r adia tion b oundar y conditions when y ou ar e using the P-1, DTRM, DO, S2S, or MC mo dels f or radia tion hea t transf er. See Defining B oundar y Conditions f or R adia tion (p.1514 ) for details . Participa tes in S olar R ay Tracing specifies whether or not the inlet v ent par ticipa tes in solar r ay tracing . Solar Transmissivit y Factor specifies a multiplier (r anging fr om 0 t o 1) tha t is applied t o the solar ir radia tion en tering the domain through the inlet v ent. Participa tes in View Factor C alcula tion specifies whether or not the inlet v ent par ticipa tes in the view fac tor calcula tion as par t of the S2S radia tion mo del. This par amet er is a vailable only if y ou selec t the Surface to Surface radia tion mo del. Species contains the sp ecies par amet ers. Specify S pecies in M ole F ractions allows you t o sp ecify the sp ecies in mole fr actions r ather than mass fr actions . 3493Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions Task P ageSpecies M ass F ractions contains inputs f or the mass fr actions of defined sp ecies . See Defining C ell Z one and B oundar y Con- ditions f or S pecies (p.1649 ) for details ab out these inputs . (These it ems will app ear only if y ou ar e modeling non-r eacting multi-sp ecies flo w or y ou ar e using the finit e-rate reaction f ormula tion.) Mean M ixture Fraction, Mixture Fraction Varianc e set inlet v alues f or the PDF mix ture fraction and its v arianc e. (These it ems will app ear only if y ou ar e using the non-pr emix ed or par tially pr emix ed c ombustion mo del.) Secondar y M ean M ixture Fraction, Secondar y M ixture Fraction Varianc e set inlet v alues f or the sec ondar y mix ture fraction and its v arianc e. (These it ems will app ear only if you ar e using the non-pr emix ed or par tially pr emix ed c ombustion mo del with t wo mix ture fractions .) Progress Variable sets the v alue of the pr ogress v ariable f or pr emix ed turbulen t combustion. See Setting B oundar y Conditions f or the P rogress Variable (p.1754 ) for details . This it em will app ear only if the pr emix ed or par tially pr emix ed c ombustion mo del is used . DPM contains the discr ete phase par amet ers. Discr ete Phase BC Type sets the w ay tha t the discr ete phase b ehaves with r espect to the b oundar y.This it em app ears when one or mor e injec tions ha ve been defined . reflec t rebounds the par ticle off the b oundar y with a change in its momen tum as defined b y the c oefficien t of restitution. (See Particle R eflec tion a t Wall in the Fluent Theor y Guide .) trap termina tes the tr ajec tory calcula tions and r ecords the fa te of the par ticle as “trapp ed”. In the c ase of e vaporating dr oplets , their en tire mass instan taneously passes in to the v apor phase and en ters the c ell adjac ent to the b oundar y. See Figur e 24.25: “Trap” Boundar y Condition f or the D iscrete Phase (p.1988 ). escape reports the par ticle as ha ving “escaped” when it enc oun ters the b oundar y.Trajec tory calcula tions are termina ted. See Figur e 24.26: “Escape” Boundar y Condition f or the D iscrete Phase (p.1988 ). wall-jet indic ates tha t the dir ection and v elocity of the dr oplet par ticles ar e giv en b y the r esulting mo- men tum flux, which is a func tion of the impingemen t angle . See Figur e 16.6: “Wall Jet” Boundar y Condition f or the D iscrete Phase in the Theor y Guide . user-defined specifies a user-defined func tion t o define the discr ete phase b oundar y condition t ype. Discr ete Phase BC F unc tion sets the user-defined func tion fr om the dr op-do wn list. Multiphase contains the multiphase par amet ers. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3494Task P age R eference GuideGranular Temp erature specifies t emp erature for the solids phase and is pr oportional t o the k inetic ener gy of the r andom motion of the par ticles . Volume F raction specifies the v olume fr action of the sec ondar y phase selec ted in the Boundar y Conditions Task Page (p.3479 ).This sec tion of the dialo g box will app ear when one of the multiphase mo dels is b eing used . See Defining M ultiphase C ell Z one and B oundar y Conditions (p.2124 ) for details . Open C hannel is available when the VOF mo del with op en channel flo w is enabled . Secondar y Phase f or Inlet is wher e the sp ecified par amet ers ar e valid only f or one sec ondar y phase . In c ase of a thr ee-phase flow, selec t the c orresponding sec ondar y phase fr om this list. This app ears when Open C hannel is enabled . Flow S pecific ation M etho d allows you t o selec t the t ype of flo w.You c an cho ose Free S urface Level and Velocity,Total H eigh t and Velocity, or Free S urface Level and Total H eigh t.This app ears when Open C hannel is enabled . Free S urface Level can b e det ermined using the absolut e value of heigh t from the fr ee sur face to the or igin in the dir ection of gr avity, or b y applying the c orrect sign based on whether the fr ee sur face level is ab ove or b elow the or igin. Total H eigh t is used as an option f or descr ibing the flo w. It is giv en b y Equa tion 26.11 (p.2149 ). Bottom L evel is valid only f or shallo w w aves.The b ottom le vel is used f or calcula ting the liquid heigh t. Velocity M agnitude sets the magnitude of the v elocity vector a t the inflo w boundar y. Level-S et F unc tion F lux app ears if the Level S et option is enabled f or the VOF mo del. Potential displa ys the b oundar y conditions f or the elec tric potential field .This tab is a vailable only if y ou ha ve enabled either the Electric P otential mo del or the Electrochemic al reaction mo del in the Species D ialog Box (p.3417 ). Potential B oundar y Condition is a dr op-do wn list of a vailable p otential b oundar y condition t ypes:Specified F lux and Specified Value . For the Specified F lux boundar y condition, you will need t o sp ecify Current Densit y at the wall. For the Specified Value boundar y condition, you will need t o sp ecify Potential at the w all. UDS contains the UDS par amet ers. User-D efined Sc alar B oundar y Condition app ears only if user-defined sc alars ar e sp ecified . 3495Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions Task P ageUser Sc alar n specifies whether the sc alar is a sp ecified flux or a sp ecified v alue . User-D efined Sc alar B oundar y Value app ears only if user-defined sc alars ar e sp ecified . User Sc alar n specifies the v alue of the sc alar. 47.8.6. Intake Fan D ialo g Box The Intake Fan dialo g box sets the b oundar y conditions f or an in take fan z one . It is op ened fr om the Boundar y Conditions Task P age (p.3479 ). See Inputs a t Intake Fan B oundar ies (p.949) for details ab out defining the it ems b elow. Controls Zone N ame sets the name of the z one . Momen tum contains the momen tum par amet ers. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3496Task P age R eference GuideReferenc e Frame specifies the r eference frame f or the in take fan. If the c ell z one adjac ent to the in take fan is mo ving , you c an cho ose t o sp ecify r elative or absolut e velocities b y selec ting Rela tive to Adjac ent Cell Z one or Absolut e in the Referenc e Frame drop-do wn list. Gauge Total P ressur e sets the gauge t otal (or stagna tion) pr essur e of the inflo w str eam. If you ar e using mo ving r eference frames , see Defining Total P ressur e and Temp erature (p.922) for inf ormation ab out r elative and absolut e total pr essur e. Supersonic/Initial G auge P ressur e sets the sta tic pr essur e on the b oundar y when the flo w becomes (lo cally) sup ersonic . It is also used to comput e initial v alues f or pr essur e, temp erature, and v elocity if the in take fan b oundar y condition is selec ted f or computing initial v alues (see Initializing the En tire Flow Field U sing S tandar d Initializa- tion (p.2605 )). Direction S pecific ation M etho d specifies the metho d you will use t o define the flo w dir ection. If you cho ose Direction Vector, you will define the flo w dir ection c omp onen ts, and if y ou cho ose Normal t o Boundar y no inputs ar e re- quir ed. See Defining the F low D irection (p.923) for inf ormation on sp ecifying flo w dir ection. Coordina te System specifies whether Cartesian ,Cylindr ical,Local C ylindr ical,or Local C ylindr ical S wirl vector com- ponen ts will b e defined .This it em will app ear only f or 3D c ases in which y ou ha ve selec ted Direction Vector as the Direction S pecific ation M etho d. X-,Y-, Z-C omp onen t of F low D irection set the dir ection of the flo w at the inlet b oundar y. For compr essible flo w, if the inflo w becomes su- personic , the v elocity is not r eoriented.These it ems will app ear if the selec ted Coordina te System is Cartesian or the mo del is 2D non-axisymmetr ic. Radial-, Tangen tial-, Axial-C omp onen t of F low D irection set the dir ection of the flo w at the inlet b oundar y. For compr essible flo w, if the inflo w becomes su- personic , the v elocity is not r eoriented.These it ems will app ear f or 2D axisymmetr ic cases , or f or 3D cases f or which the selec ted Coordina te System is Cylindr ical or Local C ylindr ical. Pressur e Jump specifies the r ise in pr essur e acr oss the fan. See Specifying the P ressur e Jump (p.950) for details . Axis Or igin sets the X,Y, and Z coordina tes of the or igin of the lo cal cylindr ical coordina te sy stem. Axis D irection sets the X,Y, and Z comp onen ts of the dir ection of the lo cal cylindr ical coordina te sy stem. Turbulenc e consists of the turbulenc e par amet ers. Specific ation M etho d specifies which metho d will b e used t o define the turbulenc e par amet ers.You c an cho ose K and Epsilon ( - mo dels and RSM only), K and Omega ( - mo dels only), Intensit y and L ength Scale,Intensit y and Visc osit y Ratio,Intensit y and H ydraulic D iamet er,Modified Turbulen t Visc osit y (Spalar t-Allmar as mo del only), or Turbulen t Visc osit y Ratio (Spalar t-Allmar as mo del 3497Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions Task P ageonly). See Determining Turbulenc e Paramet ers (p.914) for inf ormation ab out the inputs f or each of these metho ds. (This it em will app ear only f or turbulen t flo w calcula tions .) Turbulen t Kinetic E nergy,Turbulen t Dissipa tion R ate set v alues f or the turbulenc e kinetic ener gy and its dissipa tion r ate .These it ems will app ear if you cho ose K and E psilon as the Specific ation M etho d. Turbulen t Kinetic E nergy, Specific D issipa tion R ate set v alues f or the turbulenc e kinetic ener gy and its sp ecific dissipa tion r ate .These it ems will app ear if y ou cho ose K and Omega as the Specific ation M etho d. Turbulen t Intensit y,Turbulen t Length Sc ale set v alues f or turbulenc e intensit y and turbulenc e length sc ale .These it ems will app ear if y ou choose Intensit y and L ength Sc ale as the Specific ation M etho d. Turbulen t Intensit y,Turbulen t Visc osit y Ratio set v alues f or turbulenc e intensit y and turbulen t visc osity ratio .These it ems will app ear if you cho ose Intensit y and Visc osit y Ratio as the Specific ation M etho d. Turbulen t Intensit y, Hydraulic D iamet er set v alues f or turbulenc e intensit y and h ydraulic diamet er .These it ems will app ear if y ou choose Intensit y and H ydraulic D iamet er as the Specific ation M etho d. Modified Turbulen t Visc osit y sets the v alue of the mo dified turbulen t visc osity .This it em will app ear if y ou cho ose Modified Turbulen t Visc osit y as the Specific ation M etho d. Turbulen t Visc osit y Ratio sets the v alue of the turbulen t visc osity ratio .This it em will app ear if y ou cho ose Turbulen t Visc osit y Ratio as the Specific ation M etho d. Reynolds-S tress S pecific ation M etho d specifies which metho d will b e used t o det ermine the R eynolds str ess b oundar y conditions when the R eynolds str ess turbulenc e mo del is used .You c an cho ose either K or Turbulen t Intensit y or Reynolds-S tress C omp onen ts. If you cho ose the f ormer , ANSY S Fluen t will c omput e the Reynolds str esses f or y ou. If you cho ose the la tter, you will e xplicitly sp ecify the R eynolds str esses yourself . See Reynolds S tress M odel (p.1449 ) for details . (This it em will app ear only f or RSM turbulen t flow calcula tions .) UU, VV,WW , UV,VW, UW Re ynolds S tresses specify the R eynolds str ess c omp onen ts when Reynolds-S tress C omp onen ts is chosen as the Reynolds-S tress S pecific ation M etho d. Thermal contains the ther mal par amet ers. Total Temp erature sets the t otal t emp erature of the inflo w str eam. If you ar e using mo ving r eference frames , see Defining Total P ressur e and Temp erature (p.922) for inf ormation ab out r elative and absolut e total t emp erature. Radia tion contains the r adia tion par amet ers. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3498Task P age R eference GuideExternal Black B ody Temp erature M etho d, Internal E missivit y set the r adia tion b oundar y conditions when y ou ar e using the P-1, DTRM, DO, S2S, or MC mo dels f or radia tion hea t transf er. See Defining B oundar y Conditions f or R adia tion (p.1514 ) for details . Participa tes in S olar R ay Tracing specifies whether or not the in take fan par ticipa tes in solar r ay tracing . Solar Transmissivit y Factor specifies a multiplier (r anging fr om 0 t o 1) tha t is applied t o the solar ir radia tion en tering the domain through the in take fan. Participa tes in View Factor C alcula tion specifies whether or not the in take fan par ticipa tes in the view fac tor calcula tion as par t of the S2S radia tion mo del. This par amet er is a vailable only if y ou selec t the Surface to Surface radia tion mo del. Species contains the sp ecies par amet ers. Specify S pecies in M ole F ractions allows you t o sp ecify the sp ecies in mole fr actions r ather than mass fr actions . Species M ass F ractions contains inputs f or the mass fr actions of defined sp ecies . See Defining C ell Z one and B oundar y Con- ditions f or S pecies (p.1649 ) for details ab out these inputs . (These it ems will app ear only if y ou ar e modeling non-r eacting multi-sp ecies flo w or y ou ar e using the finit e-rate reaction f ormula tion.) Mean M ixture Fraction, Mixture Fraction Varianc e set inlet v alues f or the PDF mix ture fraction and its v arianc e. (These it ems will app ear only if y ou ar e using the non-pr emix ed or par tially pr emix ed c ombustion mo del.) Secondar y M ean M ixture Fraction, Secondar y M ixture Fraction Varianc e set inlet v alues f or the sec ondar y mix ture fraction and its v arianc e. (These it ems will app ear only if you ar e using the non-pr emix ed or par tially pr emix ed c ombustion mo del with t wo mix ture fractions .) Progress Variable sets the v alue of the pr ogress v ariable f or pr emix ed turbulen t combustion. See Setting B oundar y Conditions f or the P rogress Variable (p.1754 ) for details . This it em will app ear only if the pr emix ed or par tially pr emix ed c ombustion mo del is used . DPM contains the discr ete phase par amet ers. Discr ete Phase BC Type sets the w ay tha t the discr ete phase b ehaves with r espect to the b oundar y.This it em app ears when one or mor e injec tions ha ve been defined . reflec t rebounds the par ticle off the b oundar y with a change in its momen tum as defined b y the c oefficien t of restitution. (See Particle R eflec tion a t Wall in the Fluent Theor y Guide .) trap termina tes the tr ajec tory calcula tions and r ecords the fa te of the par ticle as “trapp ed”. In the c ase of e vaporating dr oplets , their en tire mass instan taneously passes in to the v apor phase and en ters 3499Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions Task P agethe c ell adjac ent to the b oundar y. See Figur e 24.25: “Trap” Boundar y Condition f or the D iscrete Phase (p.1988 ). escape reports the par ticle as ha ving “escaped” when it enc oun ters the b oundar y.Trajec tory calcula tions are termina ted. See Figur e 24.26: “Escape” Boundar y Condition f or the D iscrete Phase (p.1988 ). wall-jet indic ates tha t the dir ection and v elocity of the dr oplet par ticles ar e giv en b y the r esulting mo- men tum flux, which is a func tion of the impingemen t angle . See Figur e 16.6: “Wall Jet” Boundar y Condition f or the D iscrete Phase in the Theor y Guide . user-defined specifies a user-defined func tion t o define the discr ete phase b oundar y condition t ype. Discr ete Phase BC F unc tion sets the user-defined func tion fr om the dr op-do wn list. Multiphase contains the multiphase par amet ers. Granular Temp erature specifies t emp erature for the solids phase and is pr oportional t o the k inetic ener gy of the r andom motion of the par ticles . Volume F raction specifies the v olume fr action of the sec ondar y phase selec ted in the Boundar y Conditions Task Page (p.3479 ).This sec tion of the dialo g box will app ear when one of the multiphase mo dels is b eing used . See Defining M ultiphase C ell Z one and B oundar y Conditions (p.2124 ) for details . Potential displa ys the b oundar y conditions f or the elec tric potential field .This tab is a vailable only if y ou ha ve enabled either the Electric P otential mo del or the Electrochemic al reaction mo del in the Species D ialog Box (p.3417 ). Potential B oundar y Condition is a dr op-do wn list of a vailable p otential b oundar y condition t ypes:Specified F lux and Specified Value . For the Specified F lux boundar y condition, you will need t o sp ecify Current Densit y at the wall. For the Specified Value boundar y condition, you will need t o sp ecify Potential at the w all. UDS contains the UDS par amet ers. User-D efined Sc alar B oundar y Condition app ears only if user-defined sc alars ar e sp ecified . User Sc alar n specifies whether the sc alar is a sp ecified flux or a sp ecified v alue . User-D efined Sc alar B oundar y Value app ears only if user-defined sc alars ar e sp ecified . User Sc alar n specifies the v alue of the sc alar. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3500Task P age R eference Guide47.8.7. Interface Dialo g Box The Interface dialo g box can b e used t o mo dify the name of an in terface zone; ther e ar e no c onditions to be set. It is op ened fr om the Boundar y Conditions Task P age (p.3479 ). Interface zones ar e used f or multiple r eference frame and sliding mesh c alcula tions , and f or non-c onformal meshes . See The M ultiple Reference Frame M odel (p.1237 ),Setting U p the S liding M esh P roblem (p.1258 ), and Non-C onformal Meshes (p.741) for details . Controls Zone N ame sets the name of the z one . Non-O verlapping Z one displa ys the name of the non-o verlapping z one cr eated f or this in terface zone as par t of the cr eation of a mesh in terface. Edit... opens the b oundar y condition dialo g box of the non-o verlapping z one , so tha t you c an easily r eview and/or r evise the settings . Phase displa ys the name of the phase .This it em app ears only f or multiphase flo ws. 47.8.8. Interior D ialo g Box The Interior dialo g box can b e used t o mo dify the name of an in terior z one; ther e ar e no c onditions to be set. It is op ened fr om the Boundar y Conditions Task P age (p.3479 ). Controls Zone N ame sets the name of the z one . Phase displa ys the name of the phase .This it em app ears only f or multiphase flo ws. 3501Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions Task P age47.8.9. Mass-F low Inlet D ialo g Box The Mass-F low Inlet dialo g box sets the b oundar y conditions f or a mass-flo w inlet z one . It is op ened from the Boundar y Conditions Task P age (p.3479 ). See Inputs a t Mass-F low Inlet B oundar ies (p.935) for details ab out defining the it ems b elow. Controls Zone N ame sets the name of the z one . Momen tum displa ys the momen tum b oundar y conditions . Referenc e Frame specifies the r eference frame f or the mass flo w. If the c ell z one adjac ent to the mass-flo w inlet is moving , you c an cho ose t o sp ecify r elative or absolut e velocities b y selec ting Rela tive to Adjac ent Cell Z one or Absolut e in the Referenc e Frame drop-do wn list. Mass F low S pecific ation M etho d specifies whether y ou ar e defining Mass F low R ate,Mass F lux, or Mass F lux with A verage M ass Flux. Mass F low R ate sets the pr escr ibed mass flo w rate for the z one .This flo w rate is c onverted in ternally t o a pr escr ibed unif orm mass flux o ver the z one b y dividing the flo w rate by the flo w dir ection ar ea pr ojec tion of the Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3502Task P age R eference Guidezone .This it em will app ear if y ou selec ted Mass F low R ate in the Mass F low S pecific ation M etho d list. Imp ortant Note tha t for axisymmetr ic pr oblems , this mass flo w rate is the flo w rate thr ough the en tire ( -radian) domain, not thr ough a 1-r adian slic e. Mass F lux sets the pr escr ibed mass flux f or the z one .This it em will app ear if y ou selec ted Mass F lux or Mass Flux with A verage M ass F lux in the Mass F low S pecific ation M etho d list. Imp ortant Note tha t for axisymmetr ic pr oblems , this mass flux is the flux thr ough a 1-r adian slice of the domain. Average M ass F lux sets the a verage mass flux thr ough the z one . See More About M ass F lux and A verage M ass F lux (p.938) for details .This it em will app ear if y ou selec ted Mass F lux with A verage M ass F lux in the Mass F low Specific ation M etho d list. Imp ortant Note tha t for axisymmetr ic pr oblems , this mass flux is the flux thr ough a 1-r adian slice of the domain. Supersonic/Initializa tion G auge P ressur e sets the sta tic pr essur e tha t will b e used t o initializ e the flo w field if the mass-flo w inlet b oundar y condition is selec ted f or initializing flo w pr operties (see Initializing the En tire Flow Field U sing Standar d Initializa tion (p.2605 )). Direction S pecific ation M etho d specifies the metho d you will use t o define the flo w dir ection. If you cho ose Direction Vector, you will define the flo w dir ection c omp onen ts, and if y ou cho ose Normal t o Boundar y no inputs ar e re- quir ed. See Defining the F low D irection (p.923) for inf ormation on sp ecifying flo w dir ection. Coordina te System specifies whether Cartesian ,Cylindr ical,Local C ylindr ical,or Local C ylindr ical S wirl vector com- ponen ts will b e defined .This it em will app ear only f or 3D c ases in which y ou ha ve selec ted Direction Vector as the Direction S pecific ation M etho d. X-,Y-, Z-C omp onen t of F low D irection set the v elocity-dir ection v ector of the inflo w str eam. This v ector do es not need t o be nor maliz ed (f or example , you c an sp ecify the v ector (1 1 1) r ather than (0.577 0.577 0.577)). These it ems will app ear if the selec ted Coordina te System is Cartesian or the mo del is 2D non-axisymmetr ic. Radial-, Tangen tial-, Axial-C omp onen t of F low D irection set the v elocity-dir ection v ector of the inflo w str eam. These it ems will app ear f or 2D axisymmetr ic cases , or f or 3D c ases f or which the selec ted Coordina te System is Cylindr ical or Local C ylindr ical. 3503Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions Task P ageAxial-, Radial-C omp onen t of F low D irection, Tangen tial-V elocity app ear f or a 3D Local C ylindr ical S wirl coordina te sy stem. Axis Or igin sets the X,Y, and Z coordina tes of the or igin of the lo cal cylindr ical (swir l) coordina te sy stem. Axis D irection sets the X,Y, and Z comp onen ts of the dir ection of the lo cal cylindr ical (swir l) coordina te sy stem. Turbulenc e contains the turbulenc e par amet ers. Specific ation M etho d specifies which metho d will b e used t o define the turbulenc e par amet ers.You c an cho ose K and Epsilon ( - mo dels and RSM only), K and Omega ( - mo dels only), Intensit y and L ength Scale,Intensit y and Visc osit y Ratio,Intensit y and H ydraulic D iamet er,Modified Turbulen t Visc osit y (Spalar t-Allmar as mo del only), or Turbulen t Visc osit y Ratio (Spalar t-Allmar as mo del only). See Determining Turbulenc e Paramet ers (p.914) for inf ormation ab out the inputs f or each of these metho ds. (This it em will app ear only f or turbulen t flo w calcula tions .) Turbulen t Kinetic E nergy,Turbulen t Dissipa tion R ate set v alues f or the turbulenc e kinetic ener gy and its dissipa tion r ate .These it ems will app ear if you cho ose K and E psilon as the Specific ation M etho d. Turbulen t Kinetic E nergy, Specific D issipa tion R ate set v alues f or the turbulenc e kinetic ener gy and its sp ecific dissipa tion r ate .These it ems will app ear if y ou cho ose K and Omega as the Specific ation M etho d. Turbulen t Intensit y,Turbulen t Length Sc ale set v alues f or turbulenc e intensit y and turbulenc e length sc ale .These it ems will app ear if y ou choose Intensit y and L ength Sc ale as the Specific ation M etho d. Turbulen t Intensit y,Turbulen t Visc osit y Ratio set v alues f or turbulenc e intensit y and turbulen t visc osity ratio .These it ems will app ear if you cho ose Intensit y and Visc osit y Ratio as the Specific ation M etho d. Turbulen t Intensit y, Hydraulic D iamet er set v alues f or turbulenc e intensit y and h ydraulic diamet er .These it ems will app ear if y ou choose Intensit y and H ydraulic D iamet er as the Specific ation M etho d. Modified Turbulen t Visc osit y sets the v alue of the mo dified turbulen t visc osity .This it em will app ear if y ou cho ose Modified Turbulen t Visc osit y as the Specific ation M etho d. Turbulen t Visc osit y Ratio sets the v alue of the turbulen t visc osity ratio .This it em will app ear if y ou cho ose Turbulen t Visc osit y Ratio as the Specific ation M etho d. Reynolds-S tress S pecific ation M etho d specifies which metho d will b e used t o det ermine the R eynolds str ess b oundar y conditions when the R eynolds str ess turbulenc e mo del is used .You c an cho ose either K or Turbulen t Intensit y or Reynolds-S tress C omp onen ts. If you cho ose the f ormer , ANSY S Fluen t will c omput e the Reynolds str esses f or y ou. If you cho ose the la tter, you will e xplicitly sp ecify the R eynolds str esses Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3504Task P age R eference Guideyourself . See Reynolds S tress M odel (p.1449 ) for details . (This it em will app ear only f or RSM turbulen t flow calcula tions .) UU, VV,WW , UV,VW, UW Re ynolds S tresses specify the R eynolds str ess c omp onen ts when Reynolds-S tress C omp onen ts is chosen as the Reynolds-S tress S pecific ation M etho d. Acoustic Wave M odel contains settings f or tr eatmen t of ac oustic pr essur e waves a t the b oundar y. Off disables sp ecial tr eatmen t of ac oustic pr essur e waves a t the b oundar y. Non Reflec ting enables the gener al non-r eflec ting b oundar y condition tr eatmen t descr ibed in Gener al N on-R e- flecting B oundar y Conditions (p.1031 ). Imp edanc e enables the imp edanc e boundar y condition tr eatmen t descr ibed in Imp edanc e Boundar y Condi- tions (p.1037 ). Transpar ent Flow Forcing enables the tr anspar ent flo w forcing b oundar y condition descr ibed in Transpar ent Flow Forcing Boundar y Conditions (p.1041 ). Imp edanc e Paramet ers contains the par amet ers f or the imp edanc e boundar y condition tr eatmen t. For details r efer to Using the Imp edanc e Boundar y Condition (p.1039 ). Transpar ent Flow Forcing P aramet ers contains the par amet ers f or the tr anspar ent flo w forcing b oundar y condition tr eatmen t. For details refer to Using the Transpar ent Flow Forcing B oundar y Condition (p.1042 ). Thermal contains the ther mal par amet ers. Total Temp erature sets the t otal t emp erature of the inflo w str eam. Radia tion contains the r adia tion par amet ers. External Black B ody Temp erature M etho d, Internal E missivit y set the r adia tion b oundar y conditions when y ou ar e using the P-1, DTRM, DO, S2S, or MC mo dels f or radia tion hea t transf er. See Defining B oundar y Conditions f or R adia tion (p.1514 ) for details . Participa tes in S olar R ay Tracing specifies whether or not the mass-flo w inlet par ticipa tes in solar r ay tracing . Solar Transmissivit y Factor specifies a multiplier (r anging fr om 0 t o 1) tha t is applied t o the solar ir radia tion en tering the domain through the mass-flo w inlet. 3505Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions Task P ageParticipa tes in View Factor C alcula tion specifies whether or not the mass-flo w inlet par ticipa tes in the view fac tor calcula tion as par t of the S2S r adia tion mo del. This par amet er is a vailable only if y ou selec t the Surface to Surface radia tion model. Species contains the sp ecies par amet ers. Specify S pecies in M ole F ractions allows you t o sp ecify the sp ecies in mole fr actions r ather than mass fr actions . Species M ass F ractions contains inputs f or the mass fr actions of defined sp ecies . See Defining C ell Z one and B oundar y Con- ditions f or S pecies (p.1649 ) for details ab out these inputs .These it ems will app ear only if y ou ar e modeling non-r eacting multi-sp ecies flo w or y ou ar e using the finit e-rate reaction f ormula tion. Progress Variable sets the v alue of the pr ogress v ariable f or pr emix ed turbulen t combustion. See Setting B oundar y Conditions f or the P rogress Variable (p.1754 ) for details . This it em will app ear only if the pr emix ed or par tially pr emix ed c ombustion mo del is used . Mean M ixture Fraction, Mixture Fraction Varianc e set inlet v alues f or the PDF mix ture fraction and its v arianc e. (These it ems will app ear only if y ou ar e using the non-pr emix ed or par tially pr emix ed c ombustion mo del.) Secondar y M ean M ixture Fraction, Secondar y M ixture Fraction Varianc e set inlet v alues f or the sec ondar y mix ture fraction and its v arianc e. (These it ems will app ear only if you ar e using the non-pr emix ed or par tially pr emix ed c ombustion mo del with t wo mix ture fractions .) Scalar M ass F ractions (par tially-pr emix ed c ombustion FGM mo del only) allo ws you t o sp ecify the sc alar sp ecies mass fr actions for the tr ansp orted sc alars tha t you selec ted in the Selec t Transp orted Sc alars dialo g box. DPM contains the discr ete phase par amet ers. Discr ete Phase BC Type sets the w ay tha t the discr ete phase b ehaves with r espect to the b oundar y.This it em app ears when one or mor e injec tions ha ve been defined . reflec t rebounds the par ticle off the b oundar y with a change in its momen tum as defined b y the c oefficien t of restitution. (See Particle R eflec tion a t Wall in the Fluent Theor y Guide .) trap termina tes the tr ajec tory calcula tions and r ecords the fa te of the par ticle as “trapp ed”. In the c ase of e vaporating dr oplets , their en tire mass instan taneously passes in to the v apor phase and en ters the c ell adjac ent to the b oundar y. See Figur e 24.25: “Trap” Boundar y Condition f or the D iscrete Phase (p.1988 ). escape reports the par ticle as ha ving “escaped” when it enc oun ters the b oundar y.Trajec tory calcula tions are termina ted. See Figur e 24.26: “Escape” Boundar y Condition f or the D iscrete Phase (p.1988 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3506Task P age R eference Guidewall-jet indic ates tha t the dir ection and v elocity of the dr oplet par ticles ar e giv en b y the r esulting mo- men tum flux, which is a func tion of the impingemen t angle . See Figur e 16.6: “Wall Jet” Boundar y Condition f or the D iscrete Phase in the Theor y Guide . user-defined specifies a user-defined func tion t o define the discr ete phase b oundar y condition t ype. Discr ete Phase BC F unc tion sets the user-defined func tion fr om the dr op-do wn list. Potential displa ys the b oundar y conditions f or the elec tric potential field .This tab is a vailable only if y ou ha ve enabled either the Electric P otential mo del or the Electrochemic al reaction mo del in the Species D ialog Box (p.3417 ). Potential B oundar y Condition is a dr op-do wn list of a vailable p otential b oundar y condition t ypes:Specified F lux and Specified Value . For the Specified F lux boundar y condition, you will need t o sp ecify Current Densit y at the wall. For the Specified Value boundar y condition, you will need t o sp ecify Potential at the w all. UDS contains the UDS par amet ers. User-D efined Sc alar B oundar y Condition app ears only if user-defined sc alars ar e sp ecified . User Sc alar n specifies whether the sc alar is a sp ecified flux or a sp ecified v alue . User-D efined Sc alar B oundar y Value app ears only if user-defined sc alars ar e sp ecified . User Sc alar n specifies the v alue of the sc alar. 47.8.10. Mass-F low Outlet D ialo g Box The Mass-F low Outlet dialo g box sets the b oundar y conditions f or a mass-flo w outlet z one . It is opened fr om the Boundar y Conditions Task P age (p.3479 ). See Inputs a t Mass-F low Outlet B oundar- ies (p.943) for details ab out defining the it ems b elow. 3507Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions Task P ageControls Zone N ame sets the name of the z one . Momen tum displa ys the momen tum b oundar y conditions . Referenc e Frame specifies the r eference frame f or the mass flo w when the c ell z one adjac ent to the mass-flo w outlet is mo ving .The only a vailable option is Rela tive to Adjac ent Cell Z one , so y ou must define the mass flow relative to the adjac ent cell z one . Mass F low S pecific ation M etho d specifies whether y ou ar e defining a Mass F low R ate,Mass F lux,Mass F lux with A verage Mass F lux, or (if the densit y of the ma terial is defined either as an ideal gas or using a r eal gas model) Exit C orrected M ass F low R ate. Mass F low R ate sets the pr escr ibed mass flo w rate for the z one .This flo w rate is c onverted in ternally t o a pr escr ibed unif orm mass flux o ver the z one b y dividing the flo w rate by the flo w dir ection ar ea pr ojec tion of the zone .This it em will app ear if y ou selec ted Mass F low R ate from the Mass F low S pecific ation Metho d drop-do wn list. Imp ortant Note tha t for axisymmetr ic pr oblems , this mass flo w rate is the flo w rate thr ough the en tire ( -radian) domain, not thr ough a 1-r adian slic e. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3508Task P age R eference GuideMass F lux sets the pr escr ibed mass flux f or the z one .This it em will app ear if y ou selec ted Mass F lux or Mass Flux with A verage M ass F lux from the Mass F low S pecific ation M etho d drop-do wn list. Imp ortant Note tha t for axisymmetr ic pr oblems , this mass flux is the flux thr ough a 1-r adian slice of the domain. Average M ass F lux sets the a verage mass flux thr ough the z one . For details , see Defining the M ass F low Rate or M ass Flux (p.943).This it em will app ear if y ou selec ted Mass F lux with A verage M ass F lux from the Mass Flow S pecific ation M etho d drop-do wn list. Imp ortant Note tha t for axisymmetr ic pr oblems , this mass flux is the flux thr ough a 1-r adian slice of the domain. Exit C orrected M ass F low R ate sets the v alue f or an e xit c orrected mass flo w rate tha t is main tained b y adjusting the mass flo w rate to the t otal c onditions a t the outlet. The r esulting mass flo w rate will b e pr oportional t o the e xit t otal pressur e and in versely pr oportional t o the squar e root of the e xit t otal t emp erature (or equiv alen tly, inversely pr oportional t o the stagna tion sp eed of sound). For details , see Exit C orrected M ass F low Rate (p.946).This it em will app ear if y ou selec ted Exit C orrected M ass F low R ate from the Mass F low Specific ation M etho d drop-do wn list. Imp ortant Note tha t for axisymmetr ic pr oblems , this mass flo w rate is the flo w rate thr ough the en tire ( -radian) domain, not thr ough a 1-r adian slic e. ECMF Ref erenc e Temp erature sets the r eference temp erature for the e xit c orrected mass flo w rate; for details , see Exit C orrected Mass F low Rate (p.946).Typic ally, it is set t o be the same as the inflo w total t emp erature.This it em will app ear if y ou selec ted Exit C orrected M ass F low R ate from the Mass F low S pecific ation Metho d drop-do wn list. ECMF Ref erenc e Gauge P ressur e sets the r eference gauge pr essur e for the e xit c orrected mass flo w rate; for details , see Exit C orrected Mass F low Rate (p.946).Typic ally, it is set t o be the same as the inflo w total pr essur e.This it em will app ear if y ou selec ted Exit C orrected M ass F low R ate from the Mass F low S pecific ation M etho d drop-do wn list. Coordina te System specifies whether Cartesian ,Cylindr ical,Local C ylindr ical,or Local C ylindr ical S wirl vector com- ponen ts will b e defined .This it em will app ear only f or 3D c ases in which y ou ha ve selec ted Direction Vector as the Direction S pecific ation M etho d. 3509Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions Task P ageX-,Y-, Z-C omp onen t of F low D irection set the v elocity-dir ection v ector of the outflo w str eam. This v ector do es not need t o be nor maliz ed (for e xample , you c an sp ecify the v ector (1 1 1) r ather than (0.577 0.577 0.577)). These it ems will app ear if the selec ted Coordina te System is Cartesian or the mo del is 2D non-axisymmetr ic. Radial-, Tangen tial-, Axial-C omp onen t of F low D irection set the v elocity-dir ection v ector of the outflo w str eam. These it ems will app ear f or 2D axisymmetr ic cases , or f or 3D c ases f or which the selec ted Coordina te System is Cylindr ical or Local C ylindr ical. Axial-, Radial-C omp onen t of F low D irection, Tangen tial-V elocity app ear f or a 3D Local C ylindr ical S wirl coordina te sy stem. Axis Or igin sets the X,Y, and Z coordina tes of the or igin of the lo cal cylindr ical (swir l) coordina te sy stem. Axis D irection sets the X,Y, and Z comp onen ts of the dir ection of the lo cal cylindr ical (swir l) coordina te sy stem. Radia tion contains the r adia tion par amet ers. External Black B ody Temp erature M etho d, Black B ody Temp erature, Internal E missivit y set the r adia tion b oundar y conditions when y ou ar e using the P-1, DTRM, DO, S2S, or MC mo dels f or radia tion hea t transf er. See Defining B oundar y Conditions f or R adia tion (p.1514 ) for details . Participa tes in S olar R ay Tracing specifies whether or not the mass-flo w outlet par ticipa tes in solar r ay tracing . Solar Transmissivit y Factor specifies a multiplier (r anging fr om 0 t o 1) tha t is applied t o the solar ir radia tion en tering the domain through the mass-flo w outlet. Participa tes in View Factor C alcula tion specifies whether or not the mass-flo w outlet par ticipa tes in the view fac tor calcula tion as par t of the S2S r adia tion mo del. This par amet er is a vailable only if y ou selec t the Surface to Surface radia tion model. DPM contains the discr ete phase par amet ers. Discr ete Phase BC Type sets the w ay tha t the discr ete phase b ehaves with r espect to the b oundar y.This it em app ears when one or mor e injec tions ha ve been defined . reflec t rebounds the par ticle off the b oundar y with a change in its momen tum as defined b y the c oefficien t of restitution. (See Particle R eflec tion a t Wall in the Fluent Theor y Guide .) trap termina tes the tr ajec tory calcula tions and r ecords the fa te of the par ticle as “trapp ed”. In the c ase of e vaporating dr oplets , their en tire mass instan taneously passes in to the v apor phase and en ters the c ell adjac ent to the b oundar y. See Figur e 24.25: “Trap” Boundar y Condition f or the D iscrete Phase (p.1988 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3510Task P age R eference Guideescape reports the par ticle as ha ving “escaped” when it enc oun ters the b oundar y.Trajec tory calcula tions are termina ted. See Figur e 24.26: “Escape” Boundar y Condition f or the D iscrete Phase (p.1988 ). wall-jet indic ates tha t the dir ection and v elocity of the dr oplet par ticles ar e giv en b y the r esulting mo- men tum flux, which is a func tion of the impingemen t angle . See Figur e 16.6: “Wall Jet” Boundar y Condition f or the D iscrete Phase in the Theor y Guide . user-defined specifies a user-defined func tion t o define the discr ete phase b oundar y condition t ype. Discr ete Phase BC F unc tion sets the user-defined func tion fr om the dr op-do wn list. UDS contains the UDS par amet ers. User-D efined Sc alar B oundar y Condition app ears only if user-defined sc alars ar e sp ecified . User Sc alar n specifies whether the sc alar is a sp ecified flux or a sp ecified v alue . User-D efined Sc alar B oundar y Value app ears only if user-defined sc alars ar e sp ecified . User Sc alar n specifies the v alue of the sc alar. 47.8.11. Outflo w D ialo g Box The Outflo w dialo g box sets the b oundar y conditions f or an outflo w zone . It is op ened fr om the Boundar y Conditions Task P age (p.3479 ). See Using Outflo w Boundar ies (p.964) for details ab out using outflo w b oundar ies. Controls 3511Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions Task P ageZone N ame sets the name of the z one . Flow R ate Weigh ting specifies the p ortion of the outflo w tha t is going thr ough the b oundar y. See Mass F low Split B oundar y Conditions (p.966) for details . External Black B ody Temp erature M etho d, Internal E missivit y set the r adia tion b oundar y conditions when y ou ar e using the P-1, DTRM, DO, S2S, or MC mo dels f or ra- diation hea t transf er. See Defining B oundar y Conditions f or R adia tion (p.1514 ) for details . Discr ete Phase BC Type sets the w ay tha t the discr ete phase b ehaves with r espect to the b oundar y.This it em app ears when one or mor e injec tions ha ve been defined . reflec t rebounds the par ticle off the b oundar y with a change in its momen tum as defined b y the c oefficien t of restitution. (See Particle R eflec tion a t Wall in the Fluent Theor y Guide .) trap termina tes the tr ajec tory calcula tions and r ecords the fa te of the par ticle as “trapp ed”. In the c ase of evaporating dr oplets , their en tire mass instan taneously passes in to the v apor phase and en ters the cell adjac ent to the b oundar y. See Figur e 24.25: “Trap” Boundar y Condition f or the D iscrete Phase (p.1988 ). escape reports the par ticle as ha ving “escaped” when it enc oun ters the b oundar y.Trajec tory calcula tions ar e termina ted. See Figur e 24.26: “Escape” Boundar y Condition f or the D iscrete Phase (p.1988 ). wall-jet indic ates tha t the dir ection and v elocity of the dr oplet par ticles ar e giv en b y the r esulting momen tum flux, which is a func tion of the impingemen t angle . See Figur e 16.6: “Wall Jet” Boundar y Condition for the D iscrete Phase in the Theor y Guide . user-defined specifies a user-defined func tion t o define the discr ete phase b oundar y condition t ype. Participa tes in S olar R ay Tracing specifies whether or not outflo w par ticipa te in solar r ay tracing . Solar Transmissivit y Factor specifies a multiplier (r anging fr om 0 t o 1) tha t is applied t o the solar ir radia tion en tering the domain through the outflo w. Discr ete Phase BC F unc tion sets the user-defined func tion fr om the dr op-do wn list. Participa tes in View Factor C alcula tion specifies whether or not the outflo w par ticipa tes in the view fac tor calcula tion as par t of the S2S r adia tion model. This par amet er is a vailable only if y ou selec t the Surface to Surface radia tion mo del. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3512Task P age R eference Guide47.8.12. Outlet Vent Dialo g Box The Outlet Vent dialo g box sets the b oundar y conditions f or an outlet v ent zone . It is op ened fr om the Boundar y Conditions Task P age (p.3479 ). See Inputs a t Outlet Vent Boundar ies (p.967) for details about defining the it ems b elow. Controls Zone N ame sets the name of the z one . Momen tum contains the momen tum par amet ers. Backflo w Ref erenc e Frame specify whether backflo w temp erature, pressur e, and flo w dir ections ar e in the Absolut e or Rela tive to the A djac ent Cell Z one reference frame . Gauge P ressur e sets the gauge pr essur e at the outlet b oundar y. 3513Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions Task P ageBackflo w D irection S pecific ation M etho d specifies the metho d you will use t o define the flo w dir ection. If you cho ose Direction Vector, you will define the flo w dir ection c omp onen ts, and if y ou cho ose Normal t o Boundar y or From N eigh- boring C ell no inputs ar e requir ed. See Defining the F low D irection (p.923) for inf ormation on sp ecifying flow dir ection. Coordina te System contains a dr op-do wn list f or selec ting the c oordina te sy stem. You c an cho ose Cartesian ,Cylindr ical, or Local C ylindr ical.This option is a vailable only when Direction Vector is selec ted fr om the Backflo w Direction S pecific ation M etho d drop-do wn list. X-,Y-, Z-C omp onen t of F low D irection allows you t o sp ecify the v elocity comp onen ts in x, y, and z dir ections r espectively.This option is available when Cartesian is selec ted f or the Coordina te System. Radial-, Tangen tial-, Axial-C omp onen t of F low D irection set the dir ection of the flo w at the b oundar y.These it ems will app ear f or 2D axisymmetr ic cases , or for 3D c ases f or which the selec ted Coordina te System is Cylindr ical or Local C ylindr ical. Backflo w P ressur e Specific ation specifies ho w the pr essur e is c alcula ted under backflo w conditions . If you selec t Static P ressur e, the Gauge P ressur e is dir ectly imp osed as the b oundar y fac e pr essur e; if you selec t Total P ressur e, the Gauge P ressur e will b e combined with a d ynamic c ontribution tha t is based on the v elocity in the adjac ent cell z one . Loss-C oefficien t sets the non-dimensional loss c oefficien t used t o comput e the pr essur e dr op. See Specifying the L oss Coefficien t (p.968) for details . Axis Or igin sets the X,Y, and Z coordina tes of the or igin of the lo cal cylindr ical coordina te sy stem. Axis D irection sets the X,Y, and Z comp onen ts of the dir ection of the lo cal cylindr ical coordina te sy stem. Turbulenc e contains the turbulenc e par amet ers. Specific ation M etho d specifies which metho d will b e used t o define the turbulenc e par amet ers.You c an cho ose K and Epsilon ( - mo dels and RSM only), K and Omega ( - mo dels only), Intensit y and L ength Scale,Intensit y and Visc osit y Ratio,Intensit y and H ydraulic D iamet er,Modified Turbulen t Visc osit y (Spalar t-Allmar as mo del only), or Turbulen t Visc osit y Ratio (Spalar t-Allmar as mo del only). See Determining Turbulenc e Paramet ers (p.914) for inf ormation ab out the inputs f or each of these metho ds. (This it em will app ear only f or turbulen t flo w calcula tions .) Backflo w Turbulen t Kinetic E nergy, Backflo w Turbulen t Dissipa tion R ate set v alues f or the turbulenc e kinetic ener gy and its dissipa tion r ate .These it ems will app ear if you cho ose K and E psilon as the Specific ation M etho d. Backflo w Turbulen t Kinetic E nergy, Backflo w S pecific D issipa tion R ate set v alues f or the turbulenc e kinetic ener gy and its sp ecific dissipa tion r ate .These it ems will app ear if y ou cho ose K and Omega as the Specific ation M etho d. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3514Task P age R eference GuideBackflo w Turbulen t Intensit y, Backflo w Turbulen t Length Sc ale set v alues f or turbulenc e intensit y and turbulenc e length sc ale .These it ems will app ear if y ou choose Intensit y and L ength Sc ale as the Specific ation M etho d. Backflo w Turbulen t Intensit y, Backflo w Turbulen t Visc osit y Ratio set v alues f or turbulenc e intensit y and turbulen t visc osity ratio .These it ems will app ear if you cho ose Intensit y and Visc osit y Ratio as the Specific ation M etho d. Backflo w Turbulen t Intensit y, Backflo w H ydraulic D iamet er set v alues f or turbulenc e intensit y and h ydraulic diamet er .These it ems will app ear if y ou choose Intensit y and H ydraulic D iamet er as the Specific ation M etho d. Backflo w M odified Turbulen t Visc osit y sets the v alue of the backflo w mo dified turbulen t visc osity .This it em will app ear if y ou cho ose Modified Turbulen t Visc osit y as the Specific ation M etho d. Backflo w Turbulen t Visc osit y Ratio sets the v alue of the backflo w turbulen t visc osity ratio .This it em will app ear if y ou cho ose Turbulen t Visc osit y Ratio as the Specific ation M etho d. Reynolds-S tress S pecific ation M etho d specifies which metho d will b e used t o det ermine the backflo w Reynolds str ess b oundar y condi- tions when the R eynolds str ess turbulenc e mo del is used .You c an cho ose either K or Turbulen t Intensit y or Reynolds-S tress C omp onen ts. If you cho ose the f ormer , ANSY S Fluen t will c omput e the R eynolds str esses f or y ou. If you cho ose the la tter, you will e xplicitly sp ecify the R eynolds stresses y ourself . See Reynolds S tress M odel (p.1449 ) for details . (This it em will app ear only f or RSM turbulen t flo w calcula tions .) Backflo w UU, VV,WW , UV,VW, UW Re ynolds S tresses specify the backflo w Reynolds str ess c omp onen ts when Reynolds-S tress C omp onen ts is chosen as the Reynolds-S tress S pecific ation M etho d. Thermal contains the ther mal par amet ers. Backflo w Total Temp erature sets the t otal t emp erature of the inflo w str eam should the flo w reverse dir ection Radia tion contains the b oundar y conditions f or the r adia tion mo del a t the outlet v ent. External Black B ody Temp erature M etho d, Internal E missivit y set the r adia tion b oundar y conditions when y ou ar e using the P-1, DTRM, DO, S2S, or MC mo dels f or radia tion hea t transf er. See Defining B oundar y Conditions f or R adia tion (p.1514 ) for details . Participa tes in S olar R ay Tracing specifies whether or not the outlet v ent par ticipa tes in solar r ay tracing . Solar Transmissivit y Factor specifies a multiplier (r anging fr om 0 t o 1) tha t is applied t o the solar ir radia tion en tering the domain through the outlet v ent. 3515Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions Task P ageParticipa tes in View Factor C alcula tion specifies whether or not the outlet v ent par ticipa tes in the view fac tor calcula tion as par t of the S2S radia tion mo del. This par amet er is a vailable only if y ou selec t the Surface to Surface radia tion mo del. Species contains the sp ecies par amet ers. Specify S pecies in M ole F ractions allows you t o sp ecify the sp ecies in mole fr actions r ather than mass fr actions . Mean M ixture Fraction, Mixture Fraction Varianc e set inlet v alues f or the PDF mix ture fraction and its v arianc e. (These it ems will app ear only if y ou ar e using the non-pr emix ed or par tially pr emix ed c ombustion mo del.) Secondar y M ean M ixture Fraction, Secondar y M ixture Fraction Varianc e set inlet v alues f or the sec ondar y mix ture fraction and its v arianc e. (These it ems will app ear only if you ar e using the non-pr emix ed or par tially pr emix ed c ombustion mo del with t wo mix ture fractions .) Species M ass F ractions contains inputs f or the mass fr actions of defined sp ecies . See Defining C ell Z one and B oundar y Con- ditions f or S pecies (p.1649 ) for details ab out these inputs .These it ems will app ear only if y ou ar e modeling non-r eacting multi-sp ecies flo w or y ou ar e using the finit e-rate reaction f ormula tion. Backflo w P rogress Variable sets the v alue of the pr ogress v ariable f or pr emix ed turbulen t combustion. See Setting B oundar y Conditions f or the P rogress Variable (p.1754 ) for details . This it em will app ear only if the pr emix ed or par tially pr emix ed c ombustion mo del is used . DPM contains the discr ete phase par amet ers. Discr ete Phase BC Type sets the w ay tha t the discr ete phase b ehaves with r espect to the b oundar y.This it em app ears when one or mor e injec tions ha ve been defined . reflec t rebounds the par ticle off the b oundar y with a change in its momen tum as defined b y the c oefficien t of restitution. (See Particle R eflec tion a t Wall in the Fluent Theor y Guide .) trap termina tes the tr ajec tory calcula tions and r ecords the fa te of the par ticle as “trapp ed”. In the c ase of e vaporating dr oplets , their en tire mass instan taneously passes in to the v apor phase and en ters the c ell adjac ent to the b oundar y. See Figur e 24.25: “Trap” Boundar y Condition f or the D iscrete Phase (p.1988 ). escape reports the par ticle as ha ving “escaped” when it enc oun ters the b oundar y.Trajec tory calcula tions are termina ted. See Figur e 24.26: “Escape” Boundar y Condition f or the D iscrete Phase (p.1988 ). wall-jet indic ates tha t the dir ection and v elocity of the dr oplet par ticles ar e giv en b y the r esulting mo- men tum flux, which is a func tion of the impingemen t angle . See Figur e 16.6: “Wall Jet” Boundar y Condition f or the D iscrete Phase in the Theor y Guide . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3516Task P age R eference Guideuser-defined specifies a user-defined func tion t o define the discr ete phase b oundar y condition t ype. Discr ete Phase BC F unc tion sets the user-defined func tion fr om the dr op-do wn list. Multiphase contains the multiphase par amet ers. Backflo w G ranular Temp erature specifies t emp erature for the solids phase and is pr oportional t o the k inetic ener gy of the r andom motion of the par ticles . Volume F raction S pecific ation M etho d sets the metho d used t o sp ecify the v olume fr action of the sec ondar y phase selec ted in the Boundar y Conditions Task P age (p.3479 ).This sec tion of the dialo g box will app ear when one of the multiphase models is b eing used . See Defining M ultiphase C ell Z one and B oundar y Conditions (p.2124 ) for details . Backflo w Volume F raction specifies the v olume fr action of the sec ondar y phase as a c onstan t, profile , of UDF func tion. From N eighb oring C ell calcula tes the v olume fr action fr om the neighb oring c ells. Potential displa ys the b oundar y conditions f or the elec tric potential field .This tab is a vailable only if y ou ha ve enabled either the Electric P otential mo del or the Electrochemic al reaction mo del in the Species D ialog Box (p.3417 ). Potential B oundar y Condition is a dr op-do wn list of a vailable p otential b oundar y condition t ypes:Specified F lux and Specified Value . For the Specified F lux boundar y condition, you will need t o sp ecify Current Densit y at the wall. For the Specified Value boundar y condition, you will need t o sp ecify Potential at the w all. UDS contains the UDS par amet ers. User-D efined Sc alar B oundar y Condition app ears only if user-defined sc alars ar e sp ecified . User Sc alar n specifies whether the sc alar is a sp ecified flux or a sp ecified v alue . User-D efined Sc alar B oundar y Value app ears only if user-defined sc alars ar e sp ecified . User Sc alar n specifies the v alue of the sc alar. 47.8.13. Periodic D ialo g Box The Periodic dialo g box sets the b oundar y conditions f or a p eriodic z one . It is op ened fr om the Boundar y Conditions Task P age (p.3479 ). See Inputs f or P eriodic B oundar ies (p.1000 ) for details ab out the it ems b elow. See Periodic F lows (p.1206 ) for inf ormation ab out fully-de velop ed p eriodic flo w. 3517Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions Task P ageControls Zone N ame sets the name of the z one . Periodic Type indic ates whether the p eriodicit y of the domain is Transla tional or Rota tional . Periodic P ressur e Jump sets the pr essur e incr ease/decr ease acr oss the p eriodic b oundar y. (This it em will not app ear if the pr essur e- based (default) solv er is used; it is r elevant only f or the densit y-based solv ers.) 47.8.14. Porous Jump D ialo g Box The Porous Jump dialo g box sets the b oundar y conditions f or a p orous-jump z one . It is op ened fr om the Boundar y Conditions Task P age (p.3479 ). See Porous J ump B oundar y Conditions (p.1016 ) for details about the it ems b elow. Controls Zone N ame sets the name of the z one . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3518Task P age R eference GuideFace Permeabilit y sets the fac e permeabilit y coefficien t ( in Equa tion 7.145 (p.1016 )). Porous M edium Thick ness sets the thick ness of the p orous medium ( ). Pressur e-Jump C oefficien t sets the pr essur e-jump c oefficien t ( ). Thermal C ontact Resistanc e sets the ther mal c ontact resistanc e. Jump A dhesion sets the adhesion metho d and c ontact angle . Constr ained-T wo-Sided A dhesion constr ains the c ontact angle a t the p orous jump ,When this option is disabled then the f orced t wo- sided adhesion tr eatmen t is in eff ect. See Jump A dhesion for mor e inf ormation. Contact Angle is the c ontact angle a t the p orous jump . Discr ete Phase BC Type sets the w ay tha t the discr ete phase b ehaves with r espect to the b oundar y.This it em app ears when one or mor e injec tions ha ve been defined . interior allows the par ticles t o pass thr ough the b oundar y. reflec t rebounds the par ticle off the b oundar y with a change in its momen tum as defined b y the c oefficien t of restitution. (See Particle R eflec tion a t Wall in the Fluent Theor y Guide .) trap termina tes the tr ajec tory calcula tions and r ecords the fa te of the par ticle as “trapp ed”. In the c ase of evaporating dr oplets , their en tire mass instan taneously passes in to the v apor phase and en ters the cell adjac ent to the b oundar y. See Figur e 24.25: “Trap” Boundar y Condition f or the D iscrete Phase (p.1988 ). escape reports the par ticle as ha ving “escaped” when it enc oun ters the b oundar y.Trajec tory calcula tions ar e termina ted. See Figur e 24.26: “Escape” Boundar y Condition f or the D iscrete Phase (p.1988 ). wall-jet indic ates tha t the dir ection and v elocity of the dr oplet par ticles ar e giv en b y the r esulting momen tum flux, which is a func tion of the impingemen t angle . See Figur e 16.6: “Wall Jet” Boundar y Condition for the D iscrete Phase in the Theor y Guide . user-defined specifies a user-defined func tion t o define the discr ete phase b oundar y condition t ype. Discr ete Phase BC F unc tion sets the user-defined func tion fr om the dr op-do wn list. 3519Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions Task P ageSolar B oundar y Conditions contains the settings f or solar r ay tracing .This gr oup b ox is a vailable only if y ou selec t Solar R ay Tracing from the Model list in the Solar L oad group b ox of the Radia tion M odel dialo g box. See Solar R ay Tra- cing (p.1554 ) for details . Participa tes in S olar R ay Tracing specifies whether or not the p orous jump par ticipa tes in solar r ay tracing . Absor ptivit y contains the settings tha t define the absor ptivit y of the p orous jump . Direct Visible specifies a multiplier (r anging fr om 0 t o 1) tha t is applied t o the visible p ortion of the dir ect solar radia tion sp ectrum t o acc oun t for the absor ption of the p orous jump . Direct IR specifies a multiplier (r anging fr om 0 t o 1) tha t is applied t o the infr ared p ortion of the dir ect solar r adia tion sp ectrum t o acc oun t for the absor ption of the p orous jump . Transmissivit y contains the settings tha t define the tr ansmissivit y of the p orous jump . Direct Visible specifies a multiplier (r anging fr om 0 t o 1) tha t is applied t o the visible p ortion of the dir ect solar radia tion sp ectrum t o acc oun t for the tr ansmissivit y of the p orous jump . Direct IR specifies a multiplier (r anging fr om 0 t o 1) tha t is applied t o the infr ared p ortion of the dir ect solar r adia tion sp ectrum t o acc oun t for the tr ansmissivit y of the p orous jump . 47.8.15. Pressur e Far-F ield D ialo g Box The Pressur e Far-F ield dialo g box sets the b oundar y conditions f or a pr essur e far-field z one . It is opened fr om the Boundar y Conditions Task P age (p.3479 ). See Inputs a t Pressur e Far-F ield B oundar- ies (p.960) for details ab out defining the it ems b elow. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3520Task P age R eference GuideControls Zone N ame sets the name of the z one . Momen tum contains the momen tum par amet ers. Gauge P ressur e sets the far-field gauge sta tic pr essur e. Mach N umb er sets the far-field M ach numb er.The M ach numb er can b e subsonic , sonic , or sup ersonic . Coordina te System allows you t o selec t a Cartesian ,Cylindr ical, or Local C ylindr ical coordina te sy stem. This option is available only f or 3D geometr y. X-,Y-, Z-C omp onen t of F low D irection set the far-field flo w dir ection. These it ems will app ear if the selec ted Coordina te System is Cartesian or the mo del is 2D non-axisymmetr ic. Radial-, Tangen tial-, Axial-C omp onen t of F low D irection set the far-field flo w dir ection. These it ems will app ear f or 2D axisymmetr ic cases , or f or 3D c ases f or which the selec ted Coordina te System is Cylindr ical or Local C ylindr ical. 3521Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions Task P ageAxis Or igin sets the X,Y, and Z coordina tes of the or igin of the lo cal cylindr ical coordina te sy stem. Axis D irection sets the X,Y, and Z comp onen ts of the dir ection of the lo cal cylindr ical coordina te sy stem. Turbulenc e contains the turbulenc e par amet ers. Specific ation M etho d specifies which metho d will b e used t o define the turbulenc e par amet ers.You c an cho ose K and Epsilon ( - mo dels and RSM only), K and Omega ( - mo dels only), Intensit y and L ength Scale,Intensit y and Visc osit y Ratio,Intensit y and H ydraulic D iamet er,Modified Turbulen t Visc osit y (Spalar t-Allmar as mo del only), or Turbulen t Visc osit y Ratio (Spalar t-Allmar as mo del only). See Determining Turbulenc e Paramet ers (p.914) for inf ormation ab out the inputs f or each of these metho ds. (This it em will app ear only f or turbulen t flo w calcula tions .) Turbulen t Kinetic E nergy,Turbulen t Dissipa tion R ate set v alues f or the turbulenc e kinetic ener gy and its dissipa tion r ate .These it ems will app ear if you cho ose K and E psilon as the Specific ation M etho d. Turbulen t Kinetic E nergy, Specific D issipa tion R ate set v alues f or the turbulenc e kinetic ener gy and its sp ecific dissipa tion r ate .These it ems will app ear if y ou cho ose K and Omega as the Specific ation M etho d. Turbulen t Intensit y,Turbulen t Length Sc ale set v alues f or turbulenc e intensit y and turbulenc e length sc ale .These it ems will app ear if y ou choose Intensit y and L ength Sc ale as the Specific ation M etho d. Turbulen t Intensit y,Turbulen t Visc osit y Ratio set v alues f or turbulenc e intensit y and turbulen t visc osity ratio .These it ems will app ear if you cho ose Intensit y and Visc osit y Ratio as the Specific ation M etho d. Turbulen t Intensit y, Hydraulic D iamet er set v alues f or turbulenc e intensit y and h ydraulic diamet er .These it ems will app ear if y ou choose Intensit y and H ydraulic D iamet er as the Specific ation M etho d. Modified Turbulen t Visc osit y sets the v alue of the mo dified turbulen t visc osity .This it em will app ear if y ou cho ose Modified Turbulen t Visc osit y as the Specific ation M etho d. Turbulen t Visc osit y Ratio sets the v alue of the turbulen t visc osity ratio .This it em will app ear if y ou cho ose Turbulen t Visc osit y Ratio as the Turbulenc e Specific ation M etho d. Reynolds-S tress S pecific ation M etho d specifies which metho d will b e used t o det ermine the R eynolds str ess b oundar y conditions when the R eynolds str ess turbulenc e mo del is used .You c an cho ose either K or Turbulen t Intensit y or Reynolds-S tress C omp onen ts. If you cho ose the f ormer , ANSY S Fluen t will c omput e the Reynolds str esses f or y ou. If you cho ose the la tter, you will e xplicitly sp ecify the R eynolds str esses yourself . See Reynolds S tress M odel (p.1449 ) for details . (This it em will app ear only f or RSM turbulen t flow calcula tions .) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3522Task P age R eference GuideUU, VV,WW , UV,VW, UW Re ynolds S tresses specify the R eynolds str ess c omp onen ts when Reynolds-S tress C omp onen ts is chosen as the Reynolds-S tress S pecific ation M etho d. Thermal contains the ther mal par amet ers. Temp erature sets the far-field sta tic t emp erature. Radia tion contains the b oundar y conditions f or the r adia tion mo del a t the pr essur e far-field z one . External Black B ody Temp erature M etho d, Internal E missivit y set the r adia tion b oundar y conditions when y ou ar e using the P-1, DTRM, DO, S2S, or MC mo dels f or radia tion hea t transf er. See Defining B oundar y Conditions f or R adia tion (p.1514 ) for details . Participa tes in S olar R ay Tracing specifies whether or not the pr essur e far-field z one par ticipa tes in solar r ay tracing . Solar Transmissivit y Factor specifies a multiplier (r anging fr om 0 t o 1) tha t is applied t o the solar ir radia tion en tering the domain through the pr essur e far-field z one . Participa tes in View Factor C alcula tion specifies whether or not the pr essur e far-field z one par ticipa tes in the view fac tor calcula tion as par t of the S2S r adia tion mo del. This par amet er is a vailable only if y ou selec t the Surface to Surface radi- ation mo del. Species contains the sp ecies par amet ers. Specify S pecies in M ole F ractions allows you t o sp ecify the sp ecies in mole fr actions r ather than mass fr actions . Species M ass F ractions contains inputs f or the mass fr actions of defined sp ecies . See Defining C ell Z one and B oundar y Con- ditions f or S pecies (p.1649 ) for details ab out these inputs . (These it ems will app ear only if y ou ar e modeling non-r eacting multi-sp ecies flo w or y ou ar e using the finit e-rate reaction f ormula tion.) Mean M ixture Fraction, Mixture Fraction Varianc e set inlet v alues f or the PDF mix ture fraction and its v arianc e. (These it ems will app ear only if y ou ar e using the non-pr emix ed or par tially pr emix ed c ombustion mo del.) Secondar y M ean M ixture Fraction, Secondar y M ixture Fraction Varianc e set inlet v alues f or the sec ondar y mix ture fraction and its v arianc e. (These it ems will app ear only if you ar e using the non-pr emix ed or par tially pr emix ed c ombustion mo del with t wo mix ture fractions .) Progress Variable sets the v alue of the pr ogress v ariable f or pr emix ed turbulen t combustion. See Setting B oundar y Conditions f or the P rogress Variable (p.1754 ) for details . This it em will app ear only if the pr emix ed or par tially pr emix ed c ombustion mo del is used . 3523Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions Task P ageUDS contains the UDS par amet ers. User-D efined Sc alar B oundar y Condition app ears only if user-defined sc alars ar e sp ecified . User Sc alar n specifies whether the sc alar is a sp ecified flux or a sp ecified v alue . User-D efined Sc alar B oundar y Value app ears only if user-defined sc alars ar e sp ecified . User Sc alar n specifies the v alue of the sc alar. DPM contains the discr ete phase par amet ers. Discr ete Phase BC Type sets the w ay tha t the discr ete phase b ehaves with r espect to the b oundar y.This it em app ears when one or mor e injec tions ha ve been defined . reflec t rebounds the par ticle off the b oundar y with a change in its momen tum as defined b y the c oefficien t of restitution. (See Particle R eflec tion a t Wall in the Fluent Theor y Guide .) trap termina tes the tr ajec tory calcula tions and r ecords the fa te of the par ticle as “trapp ed”. In the c ase of e vaporating dr oplets , their en tire mass instan taneously passes in to the v apor phase and en ters the c ell adjac ent to the b oundar y. See Figur e 24.25: “Trap” Boundar y Condition f or the D iscrete Phase (p.1988 ). escape reports the par ticle as ha ving “escaped” when it enc oun ters the b oundar y.Trajec tory calcula tions are termina ted. See Figur e 24.26: “Escape” Boundar y Condition f or the D iscrete Phase (p.1988 ). wall-jet indic ates tha t the dir ection and v elocity of the dr oplet par ticles ar e giv en b y the r esulting mo- men tum flux, which is a func tion of the impingemen t angle . See Figur e 16.6: “Wall Jet” Boundar y Condition f or the D iscrete Phase in the Theor y Guide . user-defined specifies a user-defined func tion t o define the discr ete phase b oundar y condition t ype. Discr ete Phase BC F unc tion sets the user-defined func tion fr om the dr op-do wn list. 47.8.16. Pressur e Inlet D ialo g Box The Pressur e Inlet dialo g box sets the b oundar y conditions f or a pr essur e inlet z one . It is op ened fr om the Boundar y Conditions Task P age (p.3479 ). See Inputs a t Pressur e Inlet B oundar ies (p.920) for details about defining the it ems b elow. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3524Task P age R eference GuideControls Zone N ame sets the name of the z one . Momen tum contains the momen tum par amet ers. Referenc e Frame specifies the r eference frame f or the pr essur e inlet. If the c ell z one adjac ent to the pr essur e inlet is moving , you c an cho ose t o sp ecify the t otal t emp erature, total pr essur e, and v elocity comp onen ts as Rela tive to Adjac ent CellZ one or Absolut e in the Referenc e Frame drop-do wn list. Gauge Total P ressur e sets the gauge t otal (or stagna tion) pr essur e of the inflo w str eam. If you ar e using mo ving r eference frames , see Defining Total P ressur e and Temp erature (p.922) for inf ormation ab out r elative and absolut e total pr essur e. Supersonic/Initial G auge P ressur e sets the sta tic pr essur e on the b oundar y when the flo w becomes (lo cally) sup ersonic . It is also used to comput e initial v alues f or pr essur e, temp erature, and v elocity if the pr essur e inlet b oundar y condition is selec ted f or computing initial v alues (see Initializing the En tire Flow Field U sing S tandar d Initializa- tion (p.2605 )). Direction S pecific ation M etho d specifies the metho d you will use t o define the flo w dir ection. If you cho ose Direction Vector, you will define the flo w dir ection c omp onen ts, and if y ou cho ose Normal t o Boundar y no inputs ar e re- 3525Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions Task P agequir ed.You also ha ve the option t o enable Prevent Re verse F low. See Defining the F low D irec- tion (p.923) for inf ormation on sp ecifying flo w dir ection. Coordina te System specifies whether Cartesian ,Cylindr ical,Local C ylindr ical,or Local C ylindr ical S wirl vector com- ponen ts will b e defined .This it em will app ear only f or 3D c ases in which y ou ha ve selec ted Direction Vector as the Direction S pecific ation M etho d. X,Y,Z-C omp onen t of F low D irection set the dir ection of the flo w at the inlet b oundar y.These it ems will app ear if the selec ted Coordina te System is Cartesian or the mo del is 2D non-axisymmetr ic. Radial, Tangen tial, Axial C omp onen t of F low D irection set the dir ection of the flo w at the inlet b oundar y.These it ems will app ear f or 2D axisymmetr ic cases , or for 3D c ases f or which the selec ted Coordina te System is Cylindr ical or Local C ylindr ical. Radial-, Axial-C omp onen t of F low D irection, Tangen tial-V elocity app ear f or a 3D Local C ylindr ical S wirl coordina te sy stem. Axis Or igin sets the X,Y, and Z coordina tes of the or igin of the lo cal cylindr ical (swir l) coordina te sy stem. Axis D irection sets the X,Y, and Z comp onen ts of the dir ection of the lo cal cylindr ical (swir l) coordina te sy stem. Prevent Re verse F low Enables F luen t to er ect artificial w alls on the b oundar y mesh fac es to pr event flo w out of the domain. The ar tificial w alls ar e remo ved when the flo w is no longer lea ving the domain and when a fa vorable pressur e gr adien t is r ecovered a t the b oundar y mesh fac es. Fluctuating Velocity Algor ithm (only a vailable f or tr ansien t cases wher e sc ale-r esolving turbulenc e mo dels such as SAS, DES, and LES are enabled) The f ollowing metho ds ar e available: •No Perturba tions •Vortex M etho d •Spectral S ynthesiz er •Synthetic Turbulenc e Gener ator For details , see Inlet B oundar y Conditions f or Sc ale R esolving S imula tions in the Fluent Theor y Guide . Satisfy M ass C onser vation? (only a vailable f or the Vortex M etho d) For details , see Vortex Metho d in the Fluent Theor y Guide . Turbulenc e contains the turbulenc e par amet ers. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3526Task P age R eference GuideSpecific ation M etho d specifies which metho d will b e used t o define the turbulenc e par amet ers.You c an cho ose K and Epsilon ( - mo dels and RSM only), K and Omega ( - mo dels only), Intensit y and L ength Scale,Intensit y and Visc osit y Ratio,Intensit y and H ydraulic D iamet er,Modified Turbulen t Visc osit y (Spalar t-Allmar as mo del only), or Turbulen t Visc osit y Ratio (Spalar t-Allmar as mo del only). See Determining Turbulenc e Paramet ers (p.914) for inf ormation ab out the inputs f or each of these metho ds. (This it em will app ear only f or turbulen t flo w calcula tions .) Turbulen t Kinetic E nergy,Turbulen t Dissipa tion R ate set v alues f or the turbulenc e kinetic ener gy and its dissipa tion r ate .These it ems will app ear if you cho ose K and E psilon as the Specific ation M etho d. Turbulen t Kinetic E nergy, Specific D issipa tion R ate set v alues f or the turbulenc e kinetic ener gy and its sp ecific dissipa tion r ate .These it ems will app ear if y ou cho ose K and Omega as the Specific ation M etho d. Turbulen t Intensit y,Turbulen t Length Sc ale set v alues f or turbulenc e intensit y and turbulenc e length sc ale .These it ems will app ear if y ou choose Intensit y and L ength Sc ale as the Specific ation M etho d. Turbulen t Intensit y,Turbulen t Visc osit y Ratio set v alues f or turbulenc e intensit y and turbulen t visc osity ratio .These it ems will app ear if you cho ose Intensit y and Visc osit y Ratio as the Specific ation M etho d. Turbulen t Intensit y, Hydraulic D iamet er set v alues f or turbulenc e intensit y and h ydraulic diamet er .These it ems will app ear if y ou choose Intensit y and H ydraulic D iamet er as the Specific ation M etho d. Modified Turbulen t Visc osit y sets the v alue of the mo dified turbulen t visc osity .This it em will app ear if y ou cho ose Modified Turbulen t Visc osit y as the Specific ation M etho d. Turbulen t Visc osit y Ratio sets the v alue of the turbulen t visc osity ratio .This it em will app ear if y ou cho ose Turbulen t Visc osit y Ratio as the Specific ation M etho d. Reynolds-S tress S pecific ation M etho d specifies which metho d will b e used t o det ermine the R eynolds str ess b oundar y conditions when the R eynolds str ess turbulenc e mo del is used .You c an cho ose either K or Turbulen t Intensit y or Reynolds-S tress C omp onen ts. If you cho ose the f ormer , ANSY S Fluen t will c omput e the Reynolds str esses f or y ou. If you cho ose the la tter, you will e xplicitly sp ecify the R eynolds str esses yourself . See Reynolds S tress M odel (p.1449 ) for details . (This it em will app ear only f or RSM turbulen t flow calcula tions .) UU, VV,WW , UV,VW, UW Re ynolds S tresses specify the R eynolds str ess c omp onen ts when Reynolds-S tress C omp onen ts is chosen as the Reynolds-S tress S pecific ation M etho d. Acoustic Wave M odel contains settings f or tr eatmen t of ac oustic pr essur e waves a t the b oundar y. Off disables sp ecial tr eatmen t of ac oustic pr essur e waves a t the b oundar y. 3527Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions Task P ageNon Reflec ting enables the gener al non-r eflec ting b oundar y condition tr eatmen t descr ibed in Gener al N on-R e- flecting B oundar y Conditions (p.1031 ). Imp edanc e enables the imp edanc e boundar y condition tr eatmen t descr ibed in Imp edanc e Boundar y Condi- tions (p.1037 ). Transpar ent Flow Forcing enables the tr anspar ent flo w forcing b oundar y condition descr ibed in Transpar ent Flow Forcing Boundar y Conditions (p.1041 ). Imp edanc e Paramet ers contains the par amet ers f or the imp edanc e boundar y condition tr eatmen t. For details r efer to Using the Imp edanc e Boundar y Condition (p.1039 ). Transpar ent Flow Forcing P aramet ers contains the par amet ers f or the tr anspar ent flo w forcing b oundar y condition tr eatmen t. For details refer to Using the Transpar ent Flow Forcing B oundar y Condition (p.1042 ). Thermal contains the ther mal par amet ers. Total Temp erature sets the t otal t emp erature of the inflo w str eam. If you ar e using mo ving r eference frames , see Defining Total P ressur e and Temp erature (p.922) for inf ormation ab out r elative and absolut e total t emp erature. Radia tion contains the b oundar y conditions f or the r adia tion mo del a t the pr essur e inlet. External Black B ody Temp erature M etho d, Internal E missivit y set the r adia tion b oundar y conditions when y ou ar e using the P-1, DTRM, DO, S2S, or MC mo dels f or radia tion hea t transf er. See Defining B oundar y Conditions f or R adia tion (p.1514 ) for details . Participa tes in S olar R ay Tracing specifies whether or not the pr essur e inlet par ticipa tes in solar r ay tracing . Solar Transmissivit y Factor specifies a multiplier (r anging fr om 0 t o 1) tha t is applied t o the solar ir radia tion en tering the domain through the pr essur e inlet. Participa tes in View Factor C alcula tion specifies whether or not the pr essur e inlet par ticipa tes in the view fac tor calcula tion as par t of the S2S r adia tion mo del. This par amet er is a vailable only if y ou selec t the Surface to Surface radia tion model. Species contains the sp ecies par amet ers. Specify S pecies in M ole F ractions allows you t o sp ecify the sp ecies in mole fr actions r ather than mass fr actions . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3528Task P age R eference GuideSpecies M ass F ractions contains inputs f or the mass fr actions of defined sp ecies . See Defining C ell Z one and B oundar y Con- ditions f or S pecies (p.1649 ) for details ab out these inputs . (These it ems will app ear only if y ou ar e modeling non-r eacting multi-sp ecies flo w or y ou ar e using the finit e-rate reaction f ormula tion.) Mean M ixture Fraction, Mixture Fraction Varianc e set inlet v alues f or the PDF mix ture fraction and its v arianc e. (These it ems will app ear only if y ou ar e using the non-pr emix ed or par tially pr emix ed c ombustion mo del.) Secondar y M ean M ixture Fraction, Secondar y M ixture Fraction Varianc e set inlet v alues f or the sec ondar y mix ture fraction and its v arianc e. (These it ems will app ear only if you ar e using the non-pr emix ed or par tially pr emix ed c ombustion mo del with t wo mix ture fractions .) Progress Variable sets the v alue of the pr ogress v ariable f or pr emix ed turbulen t combustion. See Setting B oundar y Conditions f or the P rogress Variable (p.1754 ) for details . This it em will app ear only if the pr emix ed or par tially pr emix ed c ombustion mo del is used . Scalar M ass F ractions (par tially-pr emix ed c ombustion FGM mo del only) allo ws you t o sp ecify the sc alar sp ecies mass fr actions for the tr ansp orted sc alars tha t you selec ted in the Selec t Transp orted Sc alars dialo g box. DPM contains the discr ete phase par amet ers. Discr ete Phase BC Type sets the w ay tha t the discr ete phase b ehaves with r espect to the b oundar y.This it em app ears when one or mor e injec tions ha ve been defined . reflec t rebounds the par ticle off the b oundar y with a change in its momen tum as defined b y the c oefficien t of restitution. (See Particle R eflec tion a t Wall in the Fluent Theor y Guide .) trap termina tes the tr ajec tory calcula tions and r ecords the fa te of the par ticle as “trapp ed”. In the c ase of e vaporating dr oplets , their en tire mass instan taneously passes in to the v apor phase and en ters the c ell adjac ent to the b oundar y. See Figur e 24.25: “Trap” Boundar y Condition f or the D iscrete Phase (p.1988 ). escape reports the par ticle as ha ving “escaped” when it enc oun ters the b oundar y.Trajec tory calcula tions are termina ted. See Figur e 24.26: “Escape” Boundar y Condition f or the D iscrete Phase (p.1988 ). wall-jet indic ates tha t the dir ection and v elocity of the dr oplet par ticles ar e giv en b y the r esulting mo- men tum flux, which is a func tion of the impingemen t angle . See Figur e 16.6: “Wall Jet” Boundar y Condition f or the D iscrete Phase in the Theor y Guide . user-defined specifies a user-defined func tion t o define the discr ete phase b oundar y condition t ype. Discr ete Phase BC F unc tion sets the user-defined func tion fr om the dr op-do wn list. 3529Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions Task P ageMultiphase contains the multiphase par amet ers. Granular Temp erature specifies t emp erature for the solids phase and is pr oportional t o the k inetic ener gy of the r andom motion of the par ticles . Volume F raction specifies the v olume fr action of the sec ondar y phase selec ted in the Boundar y Conditions Task Page (p.3479 ).This sec tion of the dialo g box will app ear when one of the multiphase mo dels is b eing used . See Defining M ultiphase C ell Z one and B oundar y Conditions (p.2124 ) for details . Potential displa ys the b oundar y conditions f or the elec tric potential field .This tab is a vailable only if y ou ha ve enabled either the Electric P otential mo del or the Electrochemic al reaction mo del in the Species D ialog Box (p.3417 ). Potential B oundar y Condition is a dr op-do wn list of a vailable p otential b oundar y condition t ypes:Specified F lux and Specified Value . For the Specified F lux boundar y condition, you will need t o sp ecify Current Densit y at the wall. For the Specified Value boundar y condition, you will need t o sp ecify Potential at the w all. UDS contains the UDS par amet ers. User-D efined Sc alar B oundar y Condition app ears only if user-defined sc alars ar e sp ecified . User Sc alar n specifies whether the sc alar is a sp ecified flux or a sp ecified v alue . User-D efined Sc alar B oundar y Value app ears only if user-defined sc alars ar e sp ecified . User Sc alar n specifies the v alue of the sc alar. 47.8.17. Pressur e Outlet D ialo g Box The Pressur e Outlet dialo g box sets the b oundar y conditions f or a pr essur e outlet z one . It is op ened from the Boundar y Conditions Task P age (p.3479 ). See Inputs a t Pressur e Outlet B oundar ies (p.951) for details ab out defining the it ems b elow. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3530Task P age R eference GuideControls Zone N ame sets the name of the z one . Momen tum contains the momen tum par amet ers. Backflo w Ref erenc e Frame specify whether backflo w temp erature, pressur e, and flo w dir ections ar e in the Absolut e or Rela tive to the A djac ent Cell Z one reference frame . Gauge P ressur e sets the gauge pr essur e at the outflo w boundar y. Pressur e Profile M ultiplier sets a fac tor b y which the Gauge P ressur e is multiplied .This is pr ovided mainly f or cases wher e a non-unif orm distr ibution of the sta tic pr essur e at the pr essur e outlet b oundar y is sp ecified b y means of a pr ofile file or a user-defined func tion. 3531Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions Task P ageBackflo w D irection S pecific ation M etho d sets the dir ection of the inflo w str eam should the flo w reverse dir ection. If you cho ose Direction Vector, you will define the flo w dir ection c omp onen ts, and if y ou cho ose Normal t o Boundar y or From N eighb oring C ell, no inputs ar e requir ed.You also ha ve the option t o enable Prevent Re verse Flow. See Inputs a t Pressur e Outlet B oundar ies (p.951) for inf ormation on sp ecifying flo w dir ection. Coordina te System contains a dr op-do wn list f or selec ting the c oordina te sy stem. You c an cho ose Cartesian ,Cylindr ical, or Local C ylindr ical.This option is a vailable only when Direction Vector is selec ted fr om the Backflo w Direction S pecific ation M etho d drop-do wn list. X-,Y-, Z-C omp onen t of F low D irection allows you t o sp ecify the v elocity comp onen ts in x, y, and z dir ections r espectively.This option is available when Cartesian is selec ted f or the Coordina te System. Radial-, Tangen tial-, Axial-C omp onen t of F low D irection set the dir ection of the flo w at the b oundar y.These it ems will app ear f or 2D axisymmetr ic cases , or for 3D c ases f or which the selec ted Coordina te System is Cylindr ical or Local C ylindr ical. Backflo w P ressur e Specific ation specifies ho w the pr essur e is c alcula ted under backflo w conditions .When the NRBC option is not enabled , if you selec t Static P ressur e, the Gauge P ressur e is dir ectly imp osed as the b oundar y fac e pressur e; if you selec t Total P ressur e, the Gauge P ressur e will b e combined with a d ynamic c ontri- bution tha t is based on the v elocity in the adjac ent cell z one . For NRBCs , if you selec t Static P ressur e, the Gauge P ressur e is dir ectly imp osed as the pr essur e at infinit y; if you selec t Total P ressur e, the pressur e at infinit y is a c alcula ted v alue tha t is based on the Gauge P ressur e. Radial E quilibr ium P ressur e Distribution enables the r adial equilibr ium pr essur e distr ibution. See Defining S tatic P ressur e (p.952) for details . This it em app ears only f or 3D and axisymmetr ic swir l solv ers. Average P ressur e Specific ation allows the pr essur e along the outlet b oundar y to vary, but main tain an a verage equiv alen t to the specified v alue in the Gauge P ressur e input field . In this b oundar y implemen tation, the pr essur e variation pr ovides a lo w le vel of non-r eflec tivit y. For mor e details , see Calcula tion P rocedur e at Pressur e Outlet B oundar ies (p.955). Note The Average P ressur e Specific ation option is not a vailable if the Radial E quilibr ium Pressur e D istribution option is enabled . Target M ass F low R ate allows you t o set mass flo w rate as a b oundar y condition a t the outlet. Target M ass F low allows you t o sp ecify the flo w as either a c onstan t value or a user-defined func tion. Upper Limit of A bsolut e Pressur e, Lower Limit of A bsolut e Pressur e specifies the r ange of the pr essur e limits , which ha ve diff erent pressur e variations on diff erent boundar ies.The upp er and lo wer pr essur e limits c an b e sp ecified as a c onstan t or a pr ofile . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3532Task P age R eference GuideTurbulenc e contains the turbulenc e par amet ers. Specific ation M etho d specifies which metho d will b e used t o define the turbulenc e par amet ers.You c an cho ose K and Epsilon ( - mo dels and RSM only), K and Omega ( - mo dels only), Intensit y and L ength Scale,Intensit y and Visc osit y Ratio,Intensit y and H ydraulic D iamet er,Modified Turbulen t Visc osit y (Spalar t-Allmar as mo del only), or Turbulen t Visc osit y Ratio (Spalar t-Allmar as mo del only). See Determining Turbulenc e Paramet ers (p.914) for inf ormation ab out the inputs f or each of these metho ds. (This it em will app ear only f or turbulen t flo w calcula tions .) Backflo w Turbulen t Kinetic E nergy, Backflo w Turbulen t Dissipa tion R ate set v alues f or the turbulenc e kinetic ener gy and its dissipa tion r ate .These it ems will app ear if you cho ose K and E psilon as the Specific ation M etho d. Backflo w Turbulen t Kinetic E nergy, Backflo w S pecific D issipa tion R ate set v alues f or the turbulenc e kinetic ener gy and its sp ecific dissipa tion r ate .These it ems will app ear if y ou cho ose K and Omega as the Specific ation M etho d. Backflo w Turbulen t Intensit y, Backflo w Turbulen t Length Sc ale set v alues f or turbulenc e intensit y and turbulenc e length sc ale .These it ems will app ear if y ou choose Intensit y and L ength Sc ale as the Specific ation M etho d. Backflo w Turbulen t Intensit y, Backflo w Turbulen t Visc osit y Ratio set v alues f or turbulenc e intensit y and turbulen t visc osity ratio .These it ems will app ear if you cho ose Intensit y and Visc osit y Ratio as the Specific ation M etho d. Backflo w Turbulen t Intensit y, Backflo w H ydraulic D iamet er set v alues f or turbulenc e intensit y and h ydraulic diamet er .These it ems will app ear if y ou choose Intensit y and H ydraulic D iamet er as the Specific ation M etho d. Backflo w M odified Turbulen t Visc osit y sets the v alue of the backflo w mo dified turbulen t visc osity .This it em will app ear if y ou cho ose Modified Turbulen t Visc osit y as the Specific ation M etho d. Backflo w Turbulen t Visc osit y Ratio sets the v alue of the backflo w turbulen t visc osity ratio .This it em will app ear if y ou cho ose Turbulen t Visc osit y Ratio as the Specific ation M etho d. Reynolds-S tress S pecific ation M etho d specifies which metho d will b e used t o det ermine the backflo w Reynolds str ess b oundar y condi- tions when the R eynolds str ess turbulenc e mo del is used .You c an cho ose either K or Turbulen t Intensit y or Reynolds-S tress C omp onen ts. If you cho ose the f ormer , ANSY S Fluen t will c omput e the R eynolds str esses f or y ou. If you cho ose the la tter, you will e xplicitly sp ecify the R eynolds stresses y ourself . See Reynolds S tress M odel (p.1449 ) for details . (This it em will app ear only f or RSM turbulen t flo w calcula tions .) Backflo w UU, VV,WW , UV,VW, UW Re ynolds S tresses specify the backflo w Reynolds str ess c omp onen ts when Reynolds-S tress C omp onen ts is chosen as the Reynolds-S tress S pecific ation M etho d. Acoustic Wave M odel contains settings f or tr eatmen t of ac oustic pr essur e waves a t the b oundar y. 3533Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions Task P ageOff disables sp ecial tr eatmen t of ac oustic pr essur e waves a t the b oundar y. Non Reflec ting enables the gener al non-r eflec ting b oundar y condition tr eatmen t descr ibed in Gener al N on-R e- flecting B oundar y Conditions (p.1031 ). Imp edanc e enables the imp edanc e boundar y condition tr eatmen t descr ibed in Imp edanc e Boundar y Condi- tions (p.1037 ). Transpar ent Flow Forcing enables the tr anspar ent flo w forcing b oundar y condition descr ibed in Transpar ent Flow Forcing Boundar y Conditions (p.1041 ). Non Reflec ting P aramet ers contains settings f or the non-r eflec ting b oundar y condition tr eatmen t. Exit P ressur e Specific ation defines ho w the pr essur e is c alcula ted. For Pressur e at Infinit y, the pr essur e at the b oundar y relax es toward the Gauge P ressur e at infinit y; for Average B oundar y Pressur e, an eff ort is made to force the a verage pr essur e on the b oundar y to appr oach the Gauge P ressur e value . Imp edanc e Paramet ers contains the par amet ers f or the imp edanc e boundar y condition tr eatmen t. For details r efer to Using the Imp edanc e Boundar y Condition (p.1039 ). Transpar ent Flow Forcing P aramet ers contains the par amet ers f or the tr anspar ent flo w forcing b oundar y condition tr eatmen t. For details refer to Using the Transpar ent Flow Forcing B oundar y Condition (p.1042 ). Thermal contains the ther mal par amet ers. Backflo w Total Temp erature sets the t otal t emp erature of the inflo w str eam should the flo w reverse dir ection Radia tion contains the b oundar y conditions f or the r adia tion mo del a t the pr essur e outlet. External Black B ody Temp erature M etho d, Internal E missivit y set the r adia tion b oundar y conditions when y ou ar e using the P-1, DTRM, DO, S2S, or MC mo dels f or radia tion hea t transf er. See Defining B oundar y Conditions f or R adia tion (p.1514 ) for details . Participa tes in S olar R ay Tracing specifies whether or not the pr essur e outlet par ticipa tes in solar r ay tracing . Solar Transmissivit y Factor specifies a multiplier (r anging fr om 0 t o 1) tha t is applied t o the solar ir radia tion en tering the domain through the pr essur e outlet. Participa tes in View Factor C alcula tion specifies whether or not the pr essur e outlet par ticipa tes in the view fac tor calcula tion as par t of the S2S r adia tion mo del. This par amet er is a vailable only if y ou selec t the Surface to Surface radia tion model. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3534Task P age R eference GuideSpecies contains the sp ecies par amet ers. Specify S pecies in M ole F ractions allows you t o sp ecify the sp ecies in mole fr actions r ather than mass fr actions . Mean M ixture Fraction, Mixture Fraction Varianc e set inlet v alues f or the PDF mix ture fraction and its v arianc e. (These it ems will app ear only if y ou ar e using the non-pr emix ed or par tially pr emix ed c ombustion mo del.) Secondar y M ean M ixture Fraction, Secondar y M ixture Fraction Varianc e set inlet v alues f or the sec ondar y mix ture fraction and its v arianc e. (These it ems will app ear only if you ar e using the non-pr emix ed or par tially pr emix ed c ombustion mo del with t wo mix ture fractions .) Species M ass F ractions contains inputs f or the mass fr actions of defined sp ecies . See Defining C ell Z one and B oundar y Con- ditions f or S pecies (p.1649 ) for details ab out these inputs .These it ems will app ear only if y ou ar e modeling non-r eacting multi-sp ecies flo w or y ou ar e using the finit e-rate reaction f ormula tion. Backflo w P rogress Variable sets the v alue of the pr ogress v ariable f or pr emix ed turbulen t combustion. See Setting B oundar y Conditions f or the P rogress Variable (p.1754 ) for details . This it em will app ear only if the pr emix ed or par tially pr emix ed c ombustion mo del is used . Scalar M ass F ractions (par tially-pr emix ed c ombustion FGM mo del only) allo ws you t o sp ecify the sc alar sp ecies mass fr actions for the tr ansp orted sc alars tha t you selec ted in the Selec t Transp orted Sc alars dialo g box. DPM contains the discr ete phase par amet ers. Discr ete Phase BC Type sets the w ay tha t the discr ete phase b ehaves with r espect to the b oundar y.This it em app ears when one or mor e injec tions ha ve been defined . reflec t rebounds the par ticle off the b oundar y with a change in its momen tum as defined b y the c oefficien t of restitution. (See Particle R eflec tion a t Wall in the Fluent Theor y Guide .) trap termina tes the tr ajec tory calcula tions and r ecords the fa te of the par ticle as “trapp ed”. In the c ase of e vaporating dr oplets , their en tire mass instan taneously passes in to the v apor phase and en ters the c ell adjac ent to the b oundar y. See Figur e 24.25: “Trap” Boundar y Condition f or the D iscrete Phase (p.1988 ). escape reports the par ticle as ha ving “escaped” when it enc oun ters the b oundar y.Trajec tory calcula tions are termina ted. See Figur e 24.26: “Escape” Boundar y Condition f or the D iscrete Phase (p.1988 ). wall-jet indic ates tha t the dir ection and v elocity of the dr oplet par ticles ar e giv en b y the r esulting mo- men tum flux, which is a func tion of the impingemen t angle . See Figur e 16.6: “Wall Jet” Boundar y Condition f or the D iscrete Phase in the Theor y Guide . 3535Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions Task P ageuser-defined specifies a user-defined func tion t o define the discr ete phase b oundar y condition t ype. Discr ete Phase BC F unc tion sets the user-defined func tion fr om the dr op-do wn list. Multiphase contains the multiphase par amet ers. Backflo w G ranular Temp erature specifies t emp erature for the solids phase and is pr oportional t o the k inetic ener gy of the r andom motion of the par ticles .This option is a vailable only f or a gr anular phase with the M ixture and E uler ian multiphase mo dels . Volume F raction S pecific ation M etho d sets the metho d used t o sp ecify the v olume fr action of the sec ondar y phase selec ted in the Boundar y Conditions Task P age (p.3479 ).This sec tion of the dialo g box will app ear when one of the multiphase models is b eing used . See Defining M ultiphase C ell Z one and B oundar y Conditions (p.2124 ) for details . This c ontrol is not a vailable f or the op en channel VOF submo del. Backflo w Volume F raction specifies the v olume fr action of the sec ondar y phase as a c onstan t, profile , of UDF func tion. From N eighb oring C ell calcula tes the v olume fr action fr om the neighb oring c ells. Open C hannel (VOF mo del only) enables the op en-channel flo w boundar y condition. See Modeling Op en C hannel Flows (p.2144 ) for mor e inf ormation. This option is a vailable only when the Open C hannel VOF sub- model is selec ted in the Multiphase M odel dialo g box. Onc e you selec t this option, you c an sp ecify the f ollowing c onditions: Outlet G roup ID is used t o iden tify the diff erent outlets tha t are par t of the same outlet gr oup . See Setting the Outlet G roup (p.2147 ) for details . Pressur e Specific ation M etho d specifies which metho d will b e used t o define the b oundar y conditions a t the op en-channel pressur e outlet. You c an cho ose fr om the f ollowing options: •Free S urface Level •From N eighb oring C ell •Gauge P ressur e Refer to Pressur e Outlet in the Fluent Theor y Guide for mor e details . Secondar y Phase f or L evel S pecific ation allows you t o cho ose the desir ed sec ondar y phase .This c ontrol is a vailable only f or flo w applic ations with mor e than t wo phases . Free S urface Level can b e det ermined b y using the absolut e value of heigh t from the fr ee sur face to the or igin in the dir ection of gr avity and applying the c orrect sign based on whether the fr ee sur face level is above (p ositiv e) or b elow (nega tive) the or igin. See Determining the F ree Sur face Level (p.2147 ) for details . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3536Task P age R eference GuideBottom L evel is used f or calcula ting the liquid heigh t. It can b e det ermined as descr ibed in Determining the Bottom L evel (p.2148 ). Densit y In terpolation M etho d allows you t o sp ecify whether the mix ture densit y used in the h ydrosta tic pr ofile will b e interpol- ated using the From N eighb oring C ell,From F ree S urface Level, or Hybr id metho d. See Choosing the D ensit y Interpolation M etho d (p.2151 ) for mor e inf ormation. This dr op-do wn list is available f or sub-cr itical two-phase flo w applic ations . Potential displa ys the b oundar y conditions f or the elec tric potential field .This tab is a vailable only if y ou ha ve enabled either the Electric P otential mo del or the Electrochemic al reaction mo del in the Species D ialog Box (p.3417 ). Potential B oundar y Condition is a dr op-do wn list of a vailable p otential b oundar y condition t ypes:Specified F lux and Specified Value . For the Specified F lux boundar y condition, you will need t o sp ecify Current Densit y at the wall. For the Specified Value boundar y condition, you will need t o sp ecify Potential at the w all. UDS contains the UDS par amet ers. User-D efined Sc alar B oundar y Condition app ears only if user-defined sc alars ar e sp ecified . User Sc alar n specifies whether the sc alar is a sp ecified flux or a sp ecified v alue . User-D efined Sc alar B oundar y Value app ears only if user-defined sc alars ar e sp ecified . User Sc alar n specifies the v alue of the sc alar. 47.8.18. Radia tor D ialo g Box The Radia tor dialo g box sets the b oundar y conditions f or a r adia tor mo del z one . It is op ened fr om the Boundar y Conditions Task P age (p.3479 ). See User Inputs f or R adia tors (p.1011 ) for details ab out the items b elow. 3537Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions Task P ageControls Zone N ame sets the name of the z one . Loss C oefficien t specifies the loss c oefficien t as a c onstan t value or as a p olynomial, piec ewise-linear , or piec ewise-p oly- nomial func tion of v elocity. See Defining the P ressur e Loss C oefficien t Function (p.1012 ) for details . Heat-Transf er-C oefficien t specifies the hea t-transf er coefficien t as a c onstan t value or as a p olynomial, piec ewise-linear , or piec ewise- polynomial func tion of v elocity. See Defining the H eat Flux P aramet ers (p.1014 ) for details . Temp erature sets the t emp erature used t o comput e hea t flux fr om the r adia tor using the Heat-Transf er-C oefficien t. If Temp erature is absolut e zero, the Heat Flux condition is used inst ead. Heat Flux sets the hea t flux a t the r adia tor sur face (used only when Temp erature is absolut e zero). Discr ete Phase BC Type sets the w ay tha t the discr ete phase b ehaves with r espect to the b oundar y.This it em app ears when one or mor e injec tions ha ve been defined . interior allows the par ticles t o pass thr ough the b oundar y. reflec t rebounds the par ticle off the b oundar y with a change in its momen tum as defined b y the c oefficien t of restitution. (See Particle R eflec tion a t Wall in the Fluent Theor y Guide .) trap termina tes the tr ajec tory calcula tions and r ecords the fa te of the par ticle as “trapp ed”. In the c ase of evaporating dr oplets , their en tire mass instan taneously passes in to the v apor phase and en ters the Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3538Task P age R eference Guidecell adjac ent to the b oundar y. See Figur e 24.25: “Trap” Boundar y Condition f or the D iscrete Phase (p.1988 ). escape reports the par ticle as ha ving “escaped” when it enc oun ters the b oundar y.Trajec tory calcula tions ar e termina ted. See Figur e 24.26: “Escape” Boundar y Condition f or the D iscrete Phase (p.1988 ). wall-jet indic ates tha t the dir ection and v elocity of the dr oplet par ticles ar e giv en b y the r esulting momen tum flux, which is a func tion of the impingemen t angle . See Figur e 16.6: “Wall Jet” Boundar y Condition for the D iscrete Phase in the Theor y Guide . user-defined specifies a user-defined func tion t o define the discr ete phase b oundar y condition t ype. Discr ete Phase BC F unc tion sets the user-defined func tion fr om the dr op-do wn list. 47.8.19. RANS/LES In terface Dialo g Box The RANS/LES In terface dialo g box can b e used t o cr eate ar tificial r esolv ed turbulenc e (fluc tuation/p er- turba tions) a t the in terface wher e the flo w pr oceeds fr om the R ANS z one in to the LES z one of the computa tional domain f or Emb edded LES turbulen t flo ws. It is op ened fr om the Boundar y Conditions Task P age (p.3479 ). See Setting U p the Emb edded Lar ge E ddy Simula tion (ELES) M odel (p.1432 ) for mor e information ab out R ANS/LES in terfaces. Controls Zone N ame sets the name of the R ANS/LES in terface. Fluctuating Velocity Algor ithm displa ys the metho ds for gener ating fluc tuating v elocity comp onen ts at the R ANS/LES in terface. Available options include: •No Perturba tions •Spectral Synthesiz er •Vortex Metho d 3539Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions Task P ageNumb er of Vortices displa ys the amoun t of v ortices tha t the selec ted fluc tuating v elocity metho d distr ibut es randomly over the fac e zone and uses t o gener ate turbulen t fluc tuations (a vailable f or the Vortex Metho d only). Imp ortant The R ANS/LES 'in terface' can either b e an in terior z one (tha t has b een assigned t o be a rans-les-in terface zone), or it c an b e a non-c onformal in terface. If it is a non- conformal in terface, then y ou need t o iden tify the name of the non-c onformal in- terface's "in terior" z one (f or e xample , using the Mesh In terfaces D ialog Box (p.3852 )), and then go t o tha t zone in the Boundar y Conditions task page . 47.8.20. Symmetr y Dialo g Box The Symmetr y dialo g box can b e used t o mo dify the name of a symmetr y zone; ther e ar e no c onditions to be set. It is op ened fr om the Boundar y Conditions Task P age (p.3479 ). See Symmetr y Boundar y Conditions (p.997) for inf ormation ab out symmetr y boundar ies. Controls Zone N ame sets the name of the z one . Phase displa ys the name of the phase .This it em is a vailable only f or multiphase flo ws. 47.8.21. Velocity Inlet D ialo g Box The Velocity Inlet dialo g box sets the b oundar y conditions f or a v elocity inlet z one . It is op ened fr om the Boundar y Conditions Task P age (p.3479 ). See Inputs a t Velocity Inlet B oundar ies (p.929) for details about defining the it ems b elow. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3540Task P age R eference GuideControls Zone N ame sets the name of the z one . Phase displa ys the name of the phase .This it em app ears if the VOF, mix ture, or E uler ian multiphase mo del is being used . Open C hannel Wave BC allows you t o set sp ecific par amet ers f or a par ticular b oundar y for op en channel w ave boundar ies.This is available when the v olume of fluid multiphase mo del is selec ted. Momen tum contains the momen tum par amet ers. Velocity Specific ation M etho d sets the metho d used t o define the inflo w velocity. Flow D irection S pecific ation M etho d sets the metho d used t o define the dir ection of flo w of the w ave.This is a vailable when y ou enable the Open C hannel Wave BC option. Magnitude and D irection allows sp ecific ation in t erms of a Velocity M agnitude and Flow-D irection . Comp onen ts allows sp ecific ation in t erms of the C artesian, cylindr ical, or lo cal cylindr ical velocity comp onen ts. 3541Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions Task P ageMagnitude , Normal t o Boundar y allows sp ecific ation of a Velocity M agnitude nor mal t o the b oundar y. Referenc e Frame specifies r elative or absolut e velocity inputs .You c an cho ose t o en ter Absolut e velocities or v elocities Rela tive to Adjac ent Cell Z one . If you ar e not using mo ving r eference frames , both options ar e equiv alen t, so y ou need not cho ose. Uniform F low Velocity M agnitude is the flo w velocity, specified as a c onstan t or a par amet er. Coordina te System specifies whether Cartesian ,Cylindr ical, or Local C ylindr ical velocities will b e defined .This it em will app ear only f or 3D c ases in which y ou ha ve selec ted Magnitude and D irection or Comp onen ts as the Velocity Specific ation M etho d. X-,Y-, Z-V elocity set the c omp onen ts of the v elocity vector a t the inflo w boundar y.These it ems will app ear f or 2D non- axisymmetr ic mo dels , or f or 3D mo dels if y ou selec t the Comp onen ts option as the Velocity Specific- ation M etho d and Cartesian as the Coordina te System. Radial-, Tangen tial-, Axial-V elocity set the c omp onen ts of the v elocity vector a t the inflo w boundar y.These it ems will app ear f or 3D models if y ou selec t the Comp onen ts option as the Velocity Specific ation M etho d and Cylindr ical or Local C ylindr ical as the Coordina te System. Axial-, Radial-, Swirl-Velocity set the c omp onen ts of the v elocity vector a t the inflo w boundar y.These it ems will app ear f or 2D axisymmetr ic mo dels . Imp ortant Swirl-Velocity will app ear only f or 2D axisymmetr ic swir l mo dels . Angular Velocity specifies the angular v elocity for a 3D flo w.This it em will app ear f or a 3D mo del if y ou selec t the Comp onen ts option as the Velocity Specific ation M etho d and Cylindr ical or Local C ylindr ical as the Coordina te System. Swirl Angular Velocity specifies the swir l angular v elocity for an axisymmetr ic swir ling flo w.This it em will app ear f or an axisymmetr ic swir l mo del if y ou cho ose Comp onen ts as the Velocity Specific ation M etho d. Velocity M agnitude sets the magnitude of the v elocity vector a t the inflo w boundar y.This it em will app ear if y ou selec t the Magnitude and D irection or Magnitude , Normal t o Boundar y option as the Velocity Specific- ation M etho d. X-,Y-, Z-C omp onen t of F low D irection set the dir ection of the v elocity vector a t the inflo w boundar y.These it ems will app ear f or 2D non- axisymmetr ic mo dels if y ou selec t the Magnitude and D irection option as the Velocity Specific ation Metho d, or f or 3D mo dels if y ou selec t the Magnitude and D irection option as the Velocity Specific- ation M etho d and Cartesian as the Coordina te System. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3542Task P age R eference GuideRadial-, Tangen tial-, Axial-C omp onen t of F low D irection set the dir ection of the v elocity vector a t the inlet b oundar y.These it ems will app ear f or 3D mo dels if you selec t the Magnitude and D irection option as the Velocity Specific ation M etho d and Cyl- indr ical or Local C ylindr ical as the Coordina te System, or f or 2D axisymmetr ic mo dels . Imp ortant Tangen tial-V elocity will app ear only f or 2D axisymmetr ic swir l mo dels . Axis Or igin sets the X,Y, and Z coordina tes of the or igin of the lo cal cylindr ical coordina te sy stem. Axis D irection sets the X,Y, and Z comp onen ts of the dir ection of the lo cal cylindr ical coordina te sy stem. Outflo w G auge P ressur e specifies the pr essur e to be used as the pr essur e outlet c ondition if flo w exits the domain a t an y fac e on the v elocity inlet b oundar y. (Note tha t this eff ect is similar t o tha t of the “velocity far-field ” boundar y tha t was a vailable in R AMP ANT 3.) This it em app ears only f or the densit y-based solv ers. Fluctuating Velocity Algor ithm (only a vailable f or tr ansien t cases wher e sc ale-r esolving turbulenc e mo dels such as SAS, DES, and LES are enabled) The f ollowing metho ds ar e available: •No Perturba tions •Vortex M etho d •Spectral S ynthesiz er •Synthetic Turbulenc e Gener ator For details , see Inlet B oundar y Conditions f or Sc ale R esolving S imula tions in the Fluent Theor y Guide . Satisfy M ass C onser vation? (only a vailable f or the Vortex M etho d) For details , see Vortex Metho d in the Fluent Theor y Guide . Turbulenc e contains the turbulenc e par amet ers. Specific ation M etho d specifies which metho d will b e used t o define the turbulenc e par amet ers.You c an cho ose K and Epsilon ( - mo dels and RSM only), K and Omega ( - mo dels only), Intensit y and L ength Scale,Intensit y and Visc osit y Ratio,Intensit y and H ydraulic D iamet er,Modified Turbulen t Visc osit y (Spalar t-Allmar as mo del only), or Turbulen t Visc osit y Ratio (Spalar t-Allmar as mo del only). See Determining Turbulenc e Paramet ers (p.914) for inf ormation ab out the inputs f or each of these metho ds. (This it em will app ear only f or turbulen t flo w calcula tions .) 3543Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions Task P ageTurbulen t Kinetic E nergy,Turbulen t Dissipa tion R ate set v alues f or the turbulenc e kinetic ener gy and its dissipa tion r ate .These it ems will app ear if you cho ose K and E psilon as the Specific ation M etho d. Turbulen t Kinetic E nergy, Specific D issipa tion R ate set v alues f or the turbulenc e kinetic ener gy and its sp ecific dissipa tion r ate .These it ems will app ear if y ou cho ose K and Omega as the Specific ation M etho d. Turbulen t Intensit y,Turbulen t Length Sc ale set v alues f or turbulenc e intensit y and turbulenc e length sc ale .These it ems will app ear if y ou choose Intensit y and L ength Sc ale as the Specific ation M etho d. Turbulen t Intensit y,Turbulen t Visc osit y Ratio set v alues f or turbulenc e intensit y and turbulen t visc osity ratio .These it ems will app ear if you cho ose Intensit y and Visc osit y Ratio as the Specific ation M etho d. Turbulen t Intensit y, Hydraulic D iamet er set v alues f or turbulenc e intensit y and h ydraulic diamet er .These it ems will app ear if y ou choose Intensit y and H ydraulic D iamet er as the Specific ation M etho d. Modified Turbulen t Visc osit y sets the v alue of the mo dified turbulen t visc osity .This it em will app ear if y ou cho ose Modified Turbulen t Visc osit y as the Specific ation M etho d. Turbulen t Visc osit y Ratio sets the v alue of the turbulen t visc osity ratio .This it em will app ear if y ou cho ose Turbulen t Visc osit y Ratio as the Specific ation M etho d. Turbulen t Intensit y sets the v alue of the turbulenc e intensit y for the LES mo del. Reynolds-S tress S pecific ation M etho d specifies which metho d will b e used t o det ermine the R eynolds str ess b oundar y conditions when the R eynolds str ess turbulenc e mo del is used .You c an cho ose either K or Turbulen t Intensit y or Reynolds-S tress C omp onen ts. If you cho ose the f ormer , ANSY S Fluen t will c omput e the Reynolds str esses f or y ou. If you cho ose the la tter, you will e xplicitly sp ecify the R eynolds str esses yourself . See Reynolds S tress M odel (p.1449 ) for details . (This it em will app ear only f or RSM turbulen t flow calcula tions .) UU, VV,WW , UV,VW, UW Re ynolds S tresses specify the R eynolds str ess c omp onen ts when Reynolds-S tress C omp onen ts is chosen as the Reynolds-S tress S pecific ation M etho d. Acoustic Wave M odel contains settings f or tr eatmen t of ac oustic pr essur e waves a t the b oundar y. Off disables sp ecial tr eatmen t of ac oustic pr essur e waves a t the b oundar y. Non Reflec ting enables the gener al non-r eflec ting b oundar y condition tr eatmen t descr ibed in Gener al N on-R e- flecting B oundar y Conditions (p.1031 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3544Task P age R eference GuideImp edanc e enables the imp edanc e boundar y condition tr eatmen t descr ibed in Imp edanc e Boundar y Condi- tions (p.1037 ). Transpar ent Flow Forcing enables the tr anspar ent flo w forcing b oundar y condition descr ibed in Transpar ent Flow Forcing Boundar y Conditions (p.1041 ). Imp edanc e Paramet ers contains the par amet ers f or the imp edanc e boundar y condition tr eatmen t. For details r efer to Using the Imp edanc e Boundar y Condition (p.1039 ). Transpar ent Flow Forcing P aramet ers contains the par amet ers f or the tr anspar ent flo w forcing b oundar y condition tr eatmen t. For details refer to Using the Transpar ent Flow Forcing B oundar y Condition (p.1042 ). Thermal contains the ther mal par amet ers. Temp erature specifies the sta tic t emp erature of the flo w. Radia tion contains the b oundar y conditions f or the r adia tion mo del a t the v elocity inlet. External Black B ody Temp erature M etho d, Internal E missivit y set the r adia tion b oundar y conditions when y ou ar e using the P-1, DTRM, DO, S2S, or MC mo dels f or radia tion hea t transf er. See Defining B oundar y Conditions f or R adia tion (p.1514 ) for details . Participa tes in S olar R ay Tracing specifies whether or not the v elocity inlet par ticipa tes in solar r ay tracing . Solar Transmissivit y Factor specifies a multiplier (r anging fr om 0 t o 1) tha t is applied t o the solar ir radia tion en tering the domain through the v elocity inlet. Participa tes in View Factor C alcula tion specifies whether or not the v elocity inlet par ticipa tes in the view fac tor calcula tion as par t of the S2S radia tion mo del. This par amet er is a vailable only if y ou selec t the Surface to Surface radia tion mo del. Species contains the sp ecies par amet ers. Specify S pecies in M ole F ractions allows you t o sp ecify the sp ecies in mole fr actions r ather than mass fr actions . Species M ass F ractions contains inputs f or the mass fr actions of defined sp ecies . See Defining C ell Z one and B oundar y Con- ditions f or S pecies (p.1649 ) for details ab out these inputs .These it ems will app ear only if y ou ar e modeling non-r eacting multi-sp ecies flo w or y ou ar e using the finit e-rate reaction f ormula tion. Mean M ixture Fraction, Mixture Fraction Varianc e set inlet v alues f or the PDF mix ture fraction and its v arianc e.These it ems will app ear only if y ou ar e using the non-pr emix ed or par tially pr emix ed c ombustion mo del. 3545Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions Task P ageSecondar y M ean M ixture Fraction, Secondar y M ixture Fraction Varianc e set inlet v alues f or the sec ondar y mix ture fraction and its v arianc e. (These it ems will app ear only if you ar e using the non-pr emix ed or par tially pr emix ed c ombustion mo del with t wo mix ture fractions .) Progress Variable sets the v alue of the pr ogress v ariable f or pr emix ed turbulen t combustion. See Setting B oundar y Conditions f or the P rogress Variable (p.1754 ) for details . This it em will app ear only if the pr emix ed or par tially pr emix ed c ombustion mo del is used . Scalar M ass F ractions (par tially-pr emix ed c ombustion FGM mo del only) allo ws you t o sp ecify the sc alar sp ecies mass fr actions for the tr ansp orted sc alars tha t you selec ted in the Selec t Transp orted Sc alars dialo g box. DPM contains the discr ete phase par amet ers. Discr ete Phase BC Type sets the w ay tha t the discr ete phase b ehaves with r espect to the b oundar y.This it em app ears when one or mor e injec tions ha ve been defined . reflec t rebounds the par ticle off the b oundar y with a change in its momen tum as defined b y the c oefficien t of restitution. (See Particle R eflec tion a t Wall in the Fluent Theor y Guide .) trap termina tes the tr ajec tory calcula tions and r ecords the fa te of the par ticle as “trapp ed”. In the c ase of e vaporating dr oplets , their en tire mass instan taneously passes in to the v apor phase and en ters the c ell adjac ent to the b oundar y. See Figur e 24.25: “Trap” Boundar y Condition f or the D iscrete Phase (p.1988 ). escape reports the par ticle as ha ving “escaped” when it enc oun ters the b oundar y.Trajec tory calcula tions are termina ted. See Figur e 24.26: “Escape” Boundar y Condition f or the D iscrete Phase (p.1988 ). wall-jet indic ates tha t the dir ection and v elocity of the dr oplet par ticles ar e giv en b y the r esulting mo- men tum flux, which is a func tion of the impingemen t angle . See Figur e 16.6: “Wall Jet” Boundar y Condition f or the D iscrete Phase in the Theor y Guide . user-defined specifies a user-defined func tion t o define the discr ete phase b oundar y condition t ype. Discr ete Phase BC F unc tion sets the user-defined func tion fr om the dr op-do wn list. Multiphase contains the multiphase par amet ers. Volume F raction specifies the v olume fr action of the sec ondar y phase selec ted in the Boundar y Conditions Task Page (p.3479 ).This sec tion of the dialo g box will app ear when one of the multiphase mo dels is b eing used . See Defining M ultiphase C ell Z one and B oundar y Conditions (p.2124 ) for details . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3546Task P age R eference GuideSecondar y Phase f or Inlet specifies the sec ondar y phase t o which the par amet ers ar e applied . In c ase of a thr ee-phase flo w, selec t the c orresponding sec ondar y phase fr om this list. Wave BC Options allows you t o cho ose b etween Shallo w Waves,Shallo w/In termedia te Waves or Shor t Gravity Waves. Information ab out the t wo types of w aves is a vailable in Open C hannel Wave Boundar y Conditions in the Theor y Guide . Free S urface Level is det ermined b y using the absolut e value of heigh t from the fr ee sur face to the or igin in the dir ection of gr avity and applying the c orrect sign based on whether the fr ee sur face level is ab ove (p ositiv e) or b elow (nega tive) the or igin. Bottom L evel is valid f or shallo w and in termedia te waves.The b ottom le vel is used f or calcula ting the liquid heigh t. Referenc e Wave Direction is the dir ection of w ave pr opaga tion f or a z ero wave heading angle . Wave M odeling Options determines whether t o use w ave theor y or a w ave sp ectrum t o mo del w aves in the shallo w/in terme- diate and shor t gravity wave regimes . Numb er of Waves specifies the numb er of w aves y ou ar e defining when mo deling w aves using w ave theor y. Wave Theor y allows you t o cho ose fr om First Or der A iry (the default), Second Or der S tokes,Third Or der S tokes, Four th Or der S tokes, and Fifth Or der S tokes for shallo w/in termedia te waves and shor t gravity waves. For shallo w w aves, you c an cho ose b etween Fifth Or der S olitar y and Fifth Or der Cnoidal . Information ab out the t ypes of w ave theor y is a vailable in Open C hannel Wave Boundar y Conditions in the Theor y Guide . Wave Heigh t is the heigh t diff erence between a w ave crest t o the neighb oring tr ough. Since a solitar y wave do es not ha ve troughs , the w ave heigh t is the distanc e between a w ave crest t o mean fr ee sur face level. Wave Length is the w ave length of the shallo w w ave or shor t gravity wave. Inlet O ffset D istanc e is the tr ansla tional distanc e from the r eference point origin in the r eference wave pr opaga tion dir ection. This option is used t o gener ate a w ave from a lo cation other than the r eference frame or igin. Phase D ifferenc e is the phase diff erence between one w ave and another . Wave Heading A ngle is the angle b etween the dir ection of the w avefront and the r eference wave dir ection, in the plane of the flo w sur face. In 2D , ther e are only t wo possibilities , zero degr ees when the w ave is in the r efer- ence wave dir ection, and 180 degr ees when the w ave is in the opp osite dir ection. 3547Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions Task P ageFrequenc y Spectrum M etho d specifies the sp ectrum t o use .You c an selec t Pierson-M osk owitz (appr opriate for fully-de velop ed seas), Jonsw ap (appr opriate for fetch-limit ed seas), or TMA (appr opriate for fetch-limit ed, finit e-depth seas). Peak S hap e Paramet er controls the shap e and amplitude of the fr equenc y peak in the Jonsw ap and TMA formula tions .This corresponds t o in Equa tion 18.101 in the Fluent Theor y Guide . Signific ant Wave Heigh t is the mean w ave heigh t of the lar gest 1/3 of w aves.This c orresponds t o in Equa tion 18.100 in the Fluent Theor y Guide . Peak Wave Frequenc y is the w ave frequenc y corresponding t o the highest w ave ener gy.This c orresponds t o in Equa- tion 18.100 and Equa tion 18.101 in the Fluent Theor y Guide . can b e expressed in t erms of the p eak wave period, , as . Minimum/M aximum Wave Frequenc y specify the fr equenc y range f or the sp ectrum. Note tha t the Peak Wave Frequenc y must fall in between Minimum Wave Frequenc y and Maximum Wave Frequenc y. Numb er of F requenc y Comp onen ts specifies the numb er of c omp onen ts in to which the fr equenc y sp ectrum is divided . Direction S preading M etho d specifies the metho d to use f or sp ecifying the dir ectional spr eading char acteristics .You c an cho ose Unidir ectional (for long-cr ested w aves), Frequenc y Indep enden t Cosine F unc tion (for shor t-crested waves wher e the dir ectional c omp onen t do es not dep end on fr equenc y), and Frequenc y Dependan t Hyperb olic F unc tion (for shor t-crested w aves wher e the dir ectional c omp onen t dep ends on fr e- quenc y). Frequenc y Indep enden t Cosine E xponen t specifies the e xponen t in the F requenc y Indep enden t Cosine F unction f ormula tion. This c orresponds to in Equa tion 18.105 in the Fluent Theor y Guide . Mean Wave Heading A ngle specifies the pr incipal w ave heading dir ection. Angular S pread specifies the de viation fr om the mean w ave dir ection f or calcula ting the angular r ange . Numb er of A ngular C omp onen ts specifies the numb er of c omp onen ts in to which the angular r ange is divided . Potential displa ys the b oundar y conditions f or the elec tric potential field .This tab is a vailable only if y ou ha ve enabled either the Electric P otential mo del or the Electrochemic al reaction mo del in the Species D ialog Box (p.3417 ). Potential B oundar y Condition is a dr op-do wn list of a vailable p otential b oundar y condition t ypes:Specified F lux and Specified Value . For the Specified F lux boundar y condition, you will need t o sp ecify Current Densit y at the wall. For the Specified Value boundar y condition, you will need t o sp ecify Potential at the w all. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3548Task P age R eference GuideUDS contains the UDS par amet ers. User-D efined Sc alar B oundar y Condition app ears only if user-defined sc alars ar e sp ecified . User Sc alar n specifies whether the sc alar is a sp ecified flux or a sp ecified v alue . User-D efined Sc alar B oundar y Value app ears only if user-defined sc alars ar e sp ecified . User Sc alar n specifies the v alue of the sc alar. 47.8.22. Wall D ialo g Box The Wall dialo g box sets the b oundar y conditions f or a w all z one . It is op ened fr om the Boundar y Conditions Task P age (p.3479 ). See Inputs a t Wall B oundar ies (p.971) for details ab out defining the it ems below. 3549Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions Task P ageControls Zone N ame sets the name of the z one . Phase displa ys the name of the phase .This it em app ears if the VOF, mix ture, or E uler ian multiphase mo del is being used . Adjac ent Cell Z one shows the name of the c ell z one adjac ent to the w all. (This is f or inf ormational use only ; you c annot edit this field .) Interface Zone displa ys the name of the asso ciated in terface zone .This field app ears if this w all z one w as cr eated as a non-o verlapping z one dur ing the cr eation of a mesh in terface. It is f or inf ormational use only ; you c annot edit this field . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3550Task P age R eference GuideMomen tum displa ys the momen tum b oundar y conditions . Wall M otion contains options f or sp ecifying whether or not the w all is mo ving . Stationar y Wall specifies tha t the w all is not mo ving r elative to the adjac ent cell z one . Moving Wall enables sp ecific ation of the tangen tial w all motion. Tangen tial w all motion is applic able only t o viscous flo ws. Since the in viscid slip c ondition dec ouples the tangen tial w all v elocity from the governing equa tions , tangen tial w all motion has no eff ect on in viscid flo w. Motion contains inputs r elated t o wall motion. See Velocity Conditions f or M oving Walls (p.973) for details . Rela tive to Adjac ent Cell Z one enables the sp ecific ation of a w all v elocity relative to the v elocity of the adjac ent cell z one .(If the adjac ent cell z one is not mo ving , this is equiv alen t to Absolut e.) Absolut e enables the sp ecific ation of an absolut e wall v elocity, Transla tional enables the sp ecific ation of a tr ansla tional w all v elocity. Rota tional enables the sp ecific ation of a r otational w all v elocity. Comp onen ts enables the sp ecific ation of w all v elocity comp onen ts. Speed sets the tr ansla tional or r otational sp eed of the w all (dep ending on whether y ou selec ted Trans- lational or Rota tional ). Direction sets the dir ection v ector of the tr ansla tional v elocity. (This it em will app ear if y ou ha ve chosen the Transla tional option.) Rota tion-A xis Or igin sets the c oordina tes of the or igin of the axis of r otation, ther eby det ermining the lo cation of the axis. (This it em will app ear if y ou ha ve chosen the Rota tional option f or a non-axisymmetr ic case.) Rota tion-A xis D irection sets the dir ection v ector for the axis of r otation. (This it em will app ear if y ou ha ve chosen the Rota tional option f or a non-axisymmetr ic case.) Velocity Comp onen ts sets the X,Y, and Z-Velocity comp onen ts of the w all motion. (This it em will app ear if y ou ha ve chosen the Comp onen ts option.) Shear C ondition contains options f or sp ecifying the shear c onditions a t the w all. 3551Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions Task P ageNo Slip specifies a no-slip c ondition a t the w all. No fur ther inputs ar e requir ed. Specified S hear enables sp ecific ation of z ero or nonz ero shear . See Specified S hear (p.975) for details .This option is not a vailable f or mo ving w alls. Marangoni S tress enables the sp ecific ation of shear str ess c aused b y the v ariation of sur face tension due t o temp er- ature.This option is not a vailable f or mo ving w alls. Shear S tress contains inputs r elated t o wall shear .These it ems will app ear when Specified S hear is selec ted as the Shear C ondition . See Specified S hear (p.975) for details . X-C omp onen t,Y-C omp onen t, Z-C omp onen t, Swirl Comp onen t specify the , , and or swir l comp onen ts of shear f or a slip w all.Swirl Comp onen t is a vailable only f or axisymmetr ic swir l cases . Specular ity Coefficien t is used in multiphase gr anular flo w.You c an sp ecify the sp ecular ity coefficien t such tha t when the value is z ero, this c ondition is equiv alen t to zero shear a t the w all, but when the v alue is near unit y, ther e is a signific ant amoun t of la teral momen tum tr ansf er. Specular ity Coefficien t allows you t o en ter a v alue b etween z ero and one , which c ontrols the amoun t of la teral momen tum transf er. Marangoni S tress contains inputs r elated t o M arangoni str ess.This it em will app ear when Marangoni S tress is selec ted as the Shear C ondition . See Marangoni S tress (p.977) for details . Surface Tension G radien t specifies the sur face tension gr adien t with r espect to temp erature ( in Equa- tion 7.108 (p.977)). Wall Roughness contains v arious mo dels f or defining w all roughness siz e/heigh t in turbulen t calcula tions . Standar d uses the standar d wall roughness metho ds for most turbulenc e mo dels . See Wall R oughness E ffects in Turbulen t Wall-B ounded F lows (p.978) for details . High Roughness (Icing) contains v arious mo dels f or use only with the S palar t-Allmar as and SST k- ω turbulenc e mo dels . Specific ally applic able t o icing simula tions , cho ose fr om Specified Roughness ,NASA C orrelation , Shin-et-al , or ICE3D Roughness F ile metho ds to sp ecify the Sand-G rain Roughness . See Addi- tional R oughness M odels f or Icing S imula tions (p.982) for details . Wall A dhesion contains inputs r elated t o wall adhesion. This sec tion of the dialo g box will app ear if y ou ar e using the VOF mo del and ha ve enabled w all adhesion in the e Phase In teraction D ialog Box (p.3451 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3552Task P age R eference GuideContact Angles specifies the c ontact angle a t the w all for each pair of phases ( in Figur e 26.16: Measur ing the Contact Angle (p.2128 ) in the Theor y Guide ). See Steps f or S etting B oundar y Conditions (p.2124 ) for details . Thermal contains the ther mal par amet ers.This tab is a vailable only when the ener gy equa tion is tur ned on. Thermal C onditions contains r adio butt ons f or selec ting the ther mal b oundar y condition t ype. See Thermal B oundar y Conditions a t Walls (p.984) for details ab out these inputs: Heat Flux selec ts a sp ecified hea t flux c ondition. Temp erature selec ts a sp ecified w all temp erature condition. Convection selec ts a c onvective hea t transf er b oundar y condition mo del. Radia tion selec ts an e xternal r adia tion b oundar y condition. Mixed selec ts a c ombined c onvection/e xternal r adia tion b oundar y condition. Coupled selec ts a c oupled hea t transf er condition. It is applic able only t o walls tha t form the in terface between t wo regions (such as the fluid/solid in terface for a c onjuga te hea t transf er pr oblem). via S ystem C oupling selec ts a hea t transf er condition wher e a b oundar y can r eceive ther mal da ta (either w all temp er- ature or hea t flo w) fr om the S ystem C oupling ser vice. It is applic able when ANSY S Fluen t is c oupled with another sy stem in Workbench using S ystem C oupling (see Heat Transf er B oundar y Conditions Through S ystem C oupling (p.990) for details). via M app ed In terface specifies tha t the ther mal da ta is in terpolated acr oss a mapp ed in terface. It is a vailable only f or the in terface wall b oundar y zones cr eated as par t of a mapp ed in terface (see Heat Transf er Boundar y Conditions A cross a M app ed In terface (p.991) for details). Onc e a c ondition t ype has b een selec ted, the appr opriate conditions c an b e sp ecified . Heat Flux sets the w all hea t flux t o be used f or the Heat Flux condition. A sp ecific ation of z ero Heat Flux is simply the adiaba tic c ondition (no hea t transf er). A p ositiv e value of hea t flux implies tha t hea t en ters into the domain. Temp erature sets the w all temp erature to be used f or the Temp erature condition. 3553Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions Task P ageHeat Transf er C oefficien t sets the c onvective hea t transf er coefficien t to be used f or the Convection condition ( in Equa- tion 7.127 (p.996)). Free S tream Temp erature sets the r eference or fr ee str eam t emp erature to be used f or the Convection condition ( in Equa tion 7.127 (p.996)). External E missivit y sets the emissivit y of the e xternal w all to be used f or the Radia tion condition ( in Equa- tion 7.128 (p.996)). External R adia tion Temp erature sets the t emp erature of the e xternal r adia tion sour ce/sink t o be used f or the Radia tion condition ( in Equa tion 7.128 (p.996)). Internal E missivit y sets the in ternal emissivit y of the w all.This it em will app ear only if y ou ar e using the gr ay P-1, DO, MC, DTRM, or S2S mo dels f or radia tion hea t transf er. (Note tha t it will not app ear if y ou ar e using the non-gr ay P-1, DO, or MC mo del. In these c ases , you will en ter the Internal E missivit y for each band in the Radia tion tab .) Wall Thick ness sets the thick ness of a thin w all for the c alcula tion of ther mal r esistanc e. (See Thin-W all Thermal R es- istanc e Paramet ers (p.986) for details .) Heat Gener ation R ate sets the r ate of hea t gener ation in a w all without shell c onduc tion. Contact Resistanc e sets the c ontact resistanc e ( in Equa tion 20.23 in the Theor y Guide ) at the w all. See Modeling S olid- ification and M elting (p.2321 ) for details .This it em app ears only when the solidific ation/melting mo del is used . Material N ame sets the ma terial type for a thin w all.The c onduc tivit y of the ma terial is used f or the c alcula tion of thin-w all ther mal r esistanc e. (See Thin-W all Thermal R esistanc e Paramet ers (p.986) for details .) Mater- ial is used only when Wall Thick ness is nonz ero. Materials ar e defined with the Materials Task Page (p.3384 ). Shell C onduc tion enables shell c onduc tion f or the w all. See Shell C onduc tion (p.989) for details . Edit... is only a vailable when Shell C onduc tion is enabled , and op ens the Shell C onduc tion La yers D ialog Box (p.3926 ) in or der t o allo w you t o define the shell c onduc tion settings f or the w all. Radia tion displa ys the b oundar y conditions f or the S2S mo del, the DO mo del, the MC mo del, and the non-gr ay P- 1 mo del a t the w all.This tab is only a vailable if y ou ar e using the sur face to sur face mo del, the discr ete ordina tes mo del, the M onte Carlo mo del, or the non-gr ay P-1 mo del. See Forming Sur face Clusters (p.1498 ), Wall B oundar y Conditions f or the DO M odel (p.1516 ), and Wall B oundar y Conditions f or the DTRM, and the P-1, S2S, and R osseland M odels (p.1515 ) for details . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3554Task P age R eference GuideBC Type contains a dr op-do wn list of a vailable r adia tion b oundar y condition t ypes.The a vailable options ar e opaque and semi-tr anspar ent.This it em will app ear only if y ou ar e using the discr ete or dina tes or Monte Carlo mo del. Boundar y Sour ce enables the w all to be an e xternal r adia tion sour ce.This is only a vailable f or the MC mo del or with semi-tr anspar ent walls f or the DO mo del. Polar D istribution F unc tion enables a p olar (r otationally symmetr ic ab out a giv en dir ection) b oundar y sour ce which c an b e used if the ir radia tion in tensit y varies with dir ection such as in the c ase of LED ligh t sour ces.The p olar distr ibution func tion is defined b y an Expression or b y a table of da ta pairs c onsisting of an Angle and it's c orresponding Rela tive In tensit y.You ha ve the option t o read and wr ite the p olar da ta in the f orm of .csv files or plotting the da ta in the gr aphics windo w. Only a vailable with the MC mo del. Referenc e Direction Specify the (X,Y ,Z) v ector tha t defines the c enter of the p olar distr ibution func tion. Only a vailable with the MC mo del. Internal E missivit y specifies the in ternal emissivit y of the w all in each w avelength band .This it em will app ear only if y ou are using the non-gr ay discr ete or dina tes or M onte Carlo mo dels and y ou ha ve selec ted opaque as the BC Type, or if y ou ar e using the non-gr ay P-1 mo del. Diffuse F raction specifies the fr action of the ir radia tion tha t is t o be treated as diffuse . By default , the Diffuse F raction is set t o 1, indic ating tha t all of the ir radia tion is diffuse . If the non-gr ay DO or MC mo del is b eing used , the Diffuse F raction can b e sp ecified f or each band .This it em will app ear only if y ou ar e using the M onte Carlo or discr ete or dina tes mo del. Beam Width specifies the b eam width f or an e xternal semi-tr anspar ent wall in t erms of the Theta and Phi extents. This it em will app ear only if y ou ar e using the discr ete or dina tes radia tion mo del and y ou ha ve selec ted semi-tr anspar ent as the BC Type. Beam D irection specifies the b eam dir ection as an X,Y,Z vector.You c an sp ecify the Beam D irection as a c onstan t, a pr ofile , or a user-defined func tion. This it em will app ear only if y ou ar e using the M onte Carlo model or the discr ete or dina tes radia tion mo del and y ou ha ve selec ted semi-tr anspar ent as the BC Type. Direct Irradia tion specifies the v alue of the ir radia tion flux. If the non-gr ay DO or MC mo dels ar e being used , a constan t Direct Irradia tion can b e sp ecified f or each band . This it em will app ear only if y ou ar e using the semi-tr anspar entBC Type with the discr ete ordina tes radia tion mo del. Apply D irect Irradia tion P arallel t o the B eam is the default means of sp ecifying the sc ale of ir radia tion flux. When enabled , ANSY S Fluen t assumes that the v alue of Direct Irradia tion tha t you sp ecify is the ir radia tion flux par allel t o the Beam D irec- tion .When deselec ted, ANSY S Fluen t inst ead assumes tha t the v alue sp ecified is the flux par allel t o 3555Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions Task P agethe fac e nor mals and will c alcula te the r esulting b eam par allel flux f or e very fac e.This it em will app ear only if y ou ar e using the discr ete or dina tes mo del. Diffuse Ir radia tion specifies the v alue of the ir radia tion flux. If the non-gr ay DO mo del is b eing used , a constan t Diffuse Irradia tion can b e sp ecified f or each band . This it em will app ear only if y ou ar e using the discr ete or dina tes radia tion mo del and y ou ha ve selec ted semi-tr anspar ent as the BC Type. Solar B oundar y Conditions contains the settings f or solar r ay tracing .This gr oup b ox is a vailable only if y ou selec t Solar R ay Tracing from the Model list in the Solar L oad group b ox of the Radia tion M odel dialo g box. For semitr anspar ent coupled w alls, the solar r ay tracing settings ar e defined on the or iginal w all and not on the shado w w all. See Solar R ay Tracing (p.1554 ) for details . Participa tes in S olar R ay Tracing specifies whether or not the w all par ticipa tes in solar r ay tracing . Absor ptivit y contains the settings tha t define the absor ptivit y of w all. Direct Visible specifies a multiplier (r anging fr om 0 t o 1) tha t is applied t o the visible p ortion of the dir ect solar r adia tion sp ectrum t o acc oun t for the absor ption of the w all.The v alue should b e defined for nor mal inciden t rays. Direct IR specifies a multiplier (r anging fr om 0 t o 1) tha t is applied t o the infr ared p ortion of the dir ect solar r adia tion sp ectrum t o acc oun t for the absor ption of the w all.The v alue should b e defined for nor mal inciden t rays. Diffuse H emispher ical specifies a multiplier (r anging fr om 0 t o 1) tha t is applied t o the diffuse solar r adia tion t o ac- coun t for the absor ption of the w all.This setting is only a vailable f or semi-tr anspar ent walls. Transmissivit y contains the settings tha t define the tr ansmissivit y of w all.This gr oup b ox is only a vailable when semi-tr anspar ent is selec ted f or BC Type. Direct Visible specifies a multiplier (r anging fr om 0 t o 1) tha t is applied t o the visible p ortion of the dir ect solar r adia tion sp ectrum t o acc oun t for the tr ansmissivit y of the w all.The v alue should b e defined f or nor mal inciden t rays.This setting is only a vailable f or semi-tr anspar ent walls. Direct IR specifies a multiplier (r anging fr om 0 t o 1) tha t is applied t o the infr ared p ortion of the dir ect solar r adia tion sp ectrum t o acc oun t for the tr ansmissivit y of the w all.The v alue should b e defined f or nor mal inciden t rays.This setting is only a vailable f or semi-tr anspar ent walls. Diffuse H emispher ical specifies a multiplier (r anging fr om 0 t o 1) tha t is applied t o the diffuse solar ir radia tion t o accoun t for the tr ansmissivit y of the w all.This setting is only a vailable f or semi-tr anspar ent walls. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3556Task P age R eference GuideS2S P aramet ers contains the settings f or the S2S r adia tion mo del. This gr oup b ox is a vailable only if y ou selec t the Surface to Surface radia tion mo del. See Forming Sur face Clusters (p.1498 ) for details . Faces P er S urface Clust er sets the numb er of fac es p er sur face clust er (FPSC) f or the w all, and thus c ontrols the numb er of radia ting sur faces and (if y ou selec t Clust er to Clust er for Basis in the View Factors and C lust ering dialo g box) view fac tor sur faces. Critical Z one specifies tha t the w all is a cr itical zone .When this option is enabled , the v alue en tered f or Faces Per S urface Clust er will not b e alt ered when y ou use Automa tic clust ering in the View Factors and C lust ering dialo g box, and impac ts the c alcula tions and ac tions p erformed b y the butt ons in the Maximum D istanc e from C ritical Z one group b ox of the Participa ting B oundar y Zones dialo g box. Participa tes in View Factor C alcula tion specifies whether or not the w all par ticipa tes in the view fac tor calcula tion as par t of the S2S r a- diation mo del. This option is a vailable only if y ou selec t the Surface to Surface radia tion mo del. Species contains the sp ecies par amet ers.This tab is a vailable only if y ou ha ve enabled the Species Transp ort model in the Species M odel D ialog Box (p.3294 ). Reac tion activates reactions a t the w all.This it em will app ear only if y ou ha ve enabled an y of the r eactions in the Species M odel D ialog Box (p.3294 ). Reac tion M echanisms allows you t o sp ecify a defined gr oup , or mechanism, of a vailable r eactions .This it em will app ear only if the Reac tion option has b een tur ned on. See Defining Z one-B ased R eaction M echanisms (p.1642 ) for details ab out defining r eaction mechanisms . Surface Area Washc oat Factor allows you t o sp ecify a fac tor, which multiplies the w all ar ea to acc oun t for the incr eased sur face area of w ashc oats.This it em will app ear only if the Reac tion option has b een tur ned on. See Species Boundar y Conditions f or Walls (p.992) for details . Species B oundar y Condition contains options f or the sp ecific ation of sp ecies b oundar y conditions . See Species B oundar y Conditions for Walls (p.992) for details . Zero Diffusiv e Flux indic ates a z ero-flux c ondition f or a sp ecies .This is the default c ondition. Specified M ass F raction indic ates tha t the sp ecies mass fr action will b e sp ecified . Species M ass F ractions contains inputs f or the sp ecies mass fr actions of an y sp ecies f or which y ou ha ve selec ted Species Mass F raction as the Species B oundar y Condition . DPM contains the discr ete phase par amet ers.This tab is a vailable only if y ou ha ve defined a t least one injec tion. 3557Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions Task P ageDiscr ete Phase M odel C onditions contains inputs f or setting the fa te of par ticle tr ajec tories a t the w all.These options will app ear when one or mor e injec tions ha ve been defined . See Setting B oundar y Conditions f or the D iscrete Phase (p.1985 ) for details . Boundar y Cond .Type sets the w ay tha t the discr ete phase b ehaves with r espect to the b oundar y. reflec t rebounds the par ticle off the b oundar y with a change in its momen tum as defined b y the coefficien ts of r estitution (see Particle R eflec tion a t Wall in the Fluent Theor y Guide ).When a t least one injec tion acc oun ts for the r ough w all mo del (the Rough Wall M odel option is selec ted under the Physical M odels tab in the Set Injec tions P roperties dialo g box), you c an sp ecify the DPM Wall Roughness P aramet ers (Ra,Rq, and RSm in Equa tion 16.223 in the Fluent Theor y Guide ). (See Rough Wall M odel (p.1975 )). trap termina tes the tr ajec tory calcula tions and r ecords the fa te of the par ticle as “trapp ed”. In the case of e vaporating dr oplets , their en tire mass instan taneously passes in to the v apor phase and en ters the c ell adjac ent to the b oundar y. See Figur e 24.25: “Trap” Boundar y Condition for the D iscrete Phase (p.1988 ). escape reports the par ticle as ha ving “escaped” when it enc oun ters the b oundar y.Trajec tory calcula- tions ar e termina ted. See Figur e 24.26: “Escape” Boundar y Condition f or the D iscrete Phase (p.1988 ). wall-jet indic ates tha t the dir ection and v elocity of the dr oplet par ticles ar e giv en b y the r esulting momen tum flux, which is a func tion of the impingemen t angle . See Figur e 16.6: “Wall Jet” Boundar y Condition f or the D iscrete Phase in the Theor y Guide . wall-film allows you t o enable: •Particle-W all H eat Exchange (Particle-W all Impingemen t Heat Transf er (p.1992 )) •Film C ondensa tion (Film C ondensa tion M odel (p.1994 )) •Wall B oundar y Layer M odel (Wall B oundar y La yer M odel (p.1996 )) •Particle S tripping and sp ecify Impingemen t/Splashing M odel P aramet ers,Separ ation M odel P aramet- ers, and par amet ers f or Erosion M odels (Setting P article E rosion and A ccretion P ara- met ers (p.1996 )). Selec ting wall-film aut oma tically enables the Consider C hildr en in the S ame Track ing Step option in the Discr ete Phase M odel dialo g box (Physical M odels tab). See Discrete Phase B oundar y Condition Types (p.1986 ) for details ab out the w all-film models and their par amet ers. user-defined specifies a user-defined func tion t o define the discr ete phase b oundar y condition t ype. Boundar y Cond . Func tion sets the user-defined func tion fr om the dr op-do wn list. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3558Task P age R eference GuideDiscr ete Phase Reflec tion C oefficien ts determine the b ehavior of r eflec ting par ticles .This it em app ears when reflec t is chosen as the Boundar y Cond .Type. See Discrete Phase B oundar y Condition Types (p.1986 ) for details on setting the f ollowing it ems . Normal sets the t ype of func tion f or the nor mal c oefficien t of r estitution. This func tion c an b e constan t, piec ewise-linear ,piec ewise-p olynomial , or polynomial . Tangen t sets the t ype of func tion f or the tangen tial c oefficien t of r estitution. This func tion c an b e constan t, piec ewise-linear ,piec ewise-p olynomial , or polynomial . DEM C ollision P artner contains a list of names t o designa te the c ollision par tner . Erosion M odel contains a list of er osion mo dels . See Setting P article E rosion and A ccretion P aramet ers (p.1996 ) for details ab out these it ems . Gener ic M odel specifies er osion r ates to be comput ed using the gener ic er osion mo del. (See Accretion in the Fluent Theor y Guide for back ground inf ormation ab out this mo del.) When this mo del is enabled , you must sp ecify the er osion par amet ers in the Gener ic Erosion M odel P aramet ers dialo g box (opened b y click ing the c orresponding Edit… butt on) as descr ibed in Setting P article E rosion and A ccretion P aramet ers (p.1996 ). Finnie specifies er osion r ates to be comput ed using the F innie f ormula tion. (See Accretion in the Fluent Theor y Guide for back ground inf ormation ab out this mo del.) When this mo del is enabled , you must sp ecify the er osion par amet ers in the Finnie M odel P aramet ers dialo g box (op ened b y click ing the c orresponding Edit… butt on) as descr ibed in Setting P article E rosion and A ccretion Paramet ers (p.1996 ). McLaur y specifies er osion r ates to be comput ed using the M cLaur y formula tion. (See McLaur y Erosion Model in the Fluent Theor y Guide for back ground inf ormation ab out this mo del.) When this mo del is enabled , you must sp ecify the er osion par amet ers in the McLaur y M odel P aramet ers dialo g box (op ened b y click ing the c orresponding Edit… butt on) as descr ibed in Setting P article E rosion and A ccretion P aramet ers (p.1996 ). Oka specifies er osion r ates to be comput ed using the O ka formula tion. (See Oka Erosion M odel in the Fluent Theor y Guide for back ground inf ormation ab out this mo del.) When this mo del is enabled , you must sp ecify the er osion par amet ers in the Oka M odel P aramet ers dialo g box (op ened b y click ing the c orresponding Edit… butt on) as descr ibed in Setting P article E rosion and A ccretion Paramet ers (p.1996 ). Sheer S tress specifies er osion r ates to be comput ed using the sheer str ess mo del. (See Abrasiv e Erosion C aused by Solid P articles in the Fluent Theor y Guide for back ground inf ormation ab out this mo del.) When this mo del is enabled , you must sp ecify the er osion par amet ers in the Sheer S tress M odel Paramet ers dialo g box (op ened b y click ing the c orresponding Edit… butt on) as descr ibed in 3559Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions Task P ageSetting P article E rosion and A ccretion P aramet ers (p.1996 ).This mo del is a vailable only f or multiphase flow with a disp ersed sec ondar y gr anular phase . Granular P hase S hielding includes the shielding eff ect in other er osion mo dels tha t are cur rently enabled .The gr anular phase shielding is alw ays consider ed in the sheer str ess er osion mo del. (See Wall S hielding E ffect in D ense F low Regimes in the Fluent Theor y Guide for back ground inf ormation ab out this mo del.) This option is a vailable only when Shear S tress M odel P aramet ers is selec ted. Friction C oefficien t specifies in Equa tion 16.216 and Equa tion 16.221 in the Fluent Theor y Guide as a constan t or a piec ewise-linear ,piec ewise-p olynomial , or polynomial func tion of r elative velocity.This it em app ears only when Enable Rota tion is selec ted under the Physical M odel tab of the Set Injec tion P roperties Dialog Box (p.3917 ). UDS displa ys the b oundar y conditions f or user-defined sc alars (UDSs) a t the w all.This tab is a vailable only if you ha ve sp ecified a nonz ero numb er of user-defined sc alars in the User-D efined Sc alars D ialog Box (p.3953 ). User D efined Sc alar B oundar y Condition contains options f or the sp ecific ation of UDS b oundar y conditions . See the separ ate Fluen t Custom- ization M anual for details . Specified F lux indic ates tha t the flux of the UDS a t the w all will b e sp ecified . Specified Value indic ates tha t the v alue f or the UDS a t the w all will b e sp ecified . User D efined Sc alar B oundar y Value contains inputs f or the v alue of the flux of the UDS, or the v alue of the UDS itself , dep ending on y our selec tion f or tha t UDS under User D efined Sc alar B oundar y Condition . Wall F ilm displa ys the b oundar y conditions f or liquid films a t the w all.This tab is a vailable only if y ou ha ve enabled the E uler ian Wall F ilm mo del in the Models Task P age (p.3245 ). Euler ian F ilm Wall allows you t o define a film w all c ondition f or an y wall. See Modeling E uler ian Wall F ilms (p.2337 ) for details . Onc e this option is enabled , you c an set the f ollowing: Film C ondition Type allows you t o selec t the desir ed c ondition t ype. Boundar y Condition allows you t o sp ecify settings f or b oundar y Film C onditions : Film M ass F lux The film mass sour ce in t erms of mass flux p er unit ar ea (k g/m2–s). X-M omen tum F lux, Y-M omen tum F lux, and Z-M omen tum F lux The film momen tum sour ce in t erms of momen tum flux p er unit ar ea (N/m2). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3560Task P age R eference GuideIncoming F ilm Temp erature The film t emp erature (K). Film P assiv e Sc alar F lux The film passiv e sc alar sour ce in t erms of mass flux p er unit ar ea (k g/m2–s). Initial C ondition allows you t o sp ecify settings f or initial Film C onditions : Film H eigh t The film heigh t at the w all b oundar y. X-V elocity,Y-V elocity, and Z-V elocity The film v elocity comp onen ts at the w all b oundar y. Film Temp erature The film t emp erature (K). Film P assiv e Sc alar The film passiv e sc alar a t the w all b oundar y (dimensionless). Rela tive Film M omen tum F lux (mo ving r eference frames or mo ving w alls only) enables sp ecific ation of the film momen tum flux relative to the w all on which liquid film is defined ( Boundar y Condition type only). This option is only a vailable when Moving Wall is selec ted in the Wall dialo g box and/or Frame M otion is selec ted in the Fluid dialo g box. Rela tive Initial F ilm Velocity (mo ving r eference frames or mo ving w alls only) enables sp ecific ation of the initial v elocity relative to the w all on which liquid film is defined ( Initial C ondition type only). This option is only a vailable when Moving Wall is selec ted in the Wall dialo g box and/or Frame M otion is selec ted in the Fluid dialo g box. User S our ce Terms enables y ou t o sp ecify the additional sour ce terms t o the film c ontinuit y (Mass F lux), momen tum (X-M omen tum F lux,Y-M omen tum F lux, and Z-M omen tum F lux), ener gy (Heat Flux), and passiv e sc alar equa tions ( Scalar F lux).This option is only a vailable with initial c onditions . Flow M omen tum C oupling When this option is selec ted, the liquid film and the gas flo w will shar e the same v elocity at the interface of the liquid-gas in terface using a t wo-w ay coupling .When this option is not selec ted, the c oupling b etween the liquid film and the gas flo w is only one-w ay, namely , while the gas flo w impac ts the film flo w, the film flo w do es not impac t the bulk of the gas flo w. Film P hase C hange enables the phase change f or the selec ted w all.This option is a vailable only when Phase C hange is selec ted in the Model Options and S etup tab of the Euler ian Wall F ilm D ialog Box (p.3379 ). Onc e enabled , you c an selec t Phase C hange M odel and sp ecify its par amet ers (in the Phase C hange Paramet ers group b ox).The following mo dels ar e available: •diffusion-balanc e:You c an sp ecify Condensa tion C onstan t and Vaporization C onstan t. •wall-b oundar y-la yer: No user input is r equir ed. 3561Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions Task P age•user-defined :You c an sp ecify Condensa tion R ate and Vaporization R ate as c onstan ts, paramet ers, or pr ofile user-defined func tions (UDFs). Note tha t condensa tion and v aporization rates must b e sp ecified as p ositiv e values in k g/s. For mor e inf ormation on pr ofile UDFs , the separ ate Fluen t Customiza tion M anual . For mor e inf ormation on the phase change mo dels see Coupling of Wall F ilm with M ixture Species Transp ort in the Fluent Theor y Guide . Film C ontact Angle enables the P artial Wetting mo del. This option is a vailable only with initial c ondition when Surface Tension is selec ted in the Model Options and S etup tab of the Euler ian Wall F ilm D ialog Box (p.3379 ). Onc e this option is enabled , you c an sp ecify the Contact Angle P aramet ers: •Contact Angle : Is descr ibed in Partial Wetting E ffect in the Fluent Theor y Guide .The input range f or this par amet er is 0 t o 180 degr ees. •Rela tive Standar d D eviation : Is descr ibed in Partial Wetting E ffect in the Fluent Theor y Guide . The input f or the Rela tive Standar d D eviation should b e in the r ange of 0 t o 50%. •Contact Angle F orce Beta: Is in Equa tion 22.29 in the Fluent Theor y Guide .The input r ange for this par amet er is 0 t o 10. For mor e inf ormation on mo delling film par tial w etting eff ect see Partial Wetting E ffect in the Fluent Theor y Guide . Impingemen t Paramet ers contains par amet ers r elated t o par ticle-w all impingemen t Impingemen t Model is a dr op-do wn list tha t contains a vailable impingemen t mo dels: •stan ton-r utland (default): consists of f our impingemen t regimes: stick, rebound , spread and splash, which ar e based on the impac t ener gy and w all temp erature. See The S tanton- Rutland M odel in the Fluent Theor y Guide for details . •kuhnk e: consists of f our impingemen t regimes: stick, rebound , spread and splash (ther mal breakup). See The K uhnk e Model in the Fluent Theor y Guide for details . DPM Wall S plash allows you t o enable the w all splashing f or the selec ted w all and sp ecify the Numb er of Splashed P articles .The minimum v alue is 3. This option is a vailable when Particle S plashing is enabled in the Euler ian Wall F ilm dialo g box. Kuhnk e M odel P aramet ers (available when the kuhnk e mo del is selec ted fr om the Impingemen t Model drop-do wn list) Wall Roughness L ength enables y ou t o sp ecify w all roughness v alues used b y the K uhnk e mo del: •Ra: the w all mean r oughness tha t is used t o comput e in Equa tion 16.268 in the Fluent Theor y Guide •Rz: the a verage sur face roughness tha t is used t o comput e splashed par ticle r eflec tion angle distr ibution Equa tion 16.280 in the Fluent Theor y Guide . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3562Task P age R eference GuideCritical Temp erature Factor is the dimensionless v ariable tha t is used t o det ermine the impingemen t regime tr ansition temp erature in Equa tion 16.260 in the Fluent Theor y Guide . Potential displa ys the b oundar y conditions f or the elec tric potential field a t the w all.This tab is a vailable only if you ha ve enabled either the Electric P otential mo del under the Model tree br anch or the Electrochem- ical Reaction mo del in the Species D ialog Box (p.3417 ). Electrochemic al Reac tion enables elec trochemic al reactions a t the w all.This option is a vailable only if Electrochemic al reactions are enabled in the Species M odel dialo g box. Faradaic H eat (if enabled) includes hea t from the elec trochemic al reaction in the ener gy equa tion. This option is available only if Electrochemic al reactions ar e enabled in the Species M odel dialo g box. Reac tion M echanism contains a dr op-do wn list of all a vailable elec trochemic al reaction mechanisms .This option is a vailable only if Electrochemic al reactions ar e enabled in the Species M odel dialo g box. Potential B oundar y Condition contains a dr op-do wn list of a vailable p otential b oundar y condition t ypes for the e xternal w all.You will need t o sp ecify one of the f ollowing: •Current Densit y (Selec t the Specified F lux potential b oundar y condition) •Potential at the w all (S elec t the Specified Value potential b oundar y condition) This c ontrol is a vailable only f or one-sided e xternal w alls. For two-sided in ternal w alls, the solv er alw ays uses the c oupled tr eatmen t. Contact Resistanc e is the c ontact resistanc e at the w all, in Equa tion 23.3 in the Fluent Theor y Guide . For two-sided in- ternal w alls, you only need t o define the c ontact resistanc e at one of the w alls.The v alue y ou sp ecify will b e aut oma tically c opied t o the other side of the w all. Structure contains the displac emen t boundar y condition settings f or w alls tha t are adjac ent to solid c ell z ones .This tab is only a vailable when a mo del is selec ted in the Structural M odel D ialog Box (p.3378 ). X-D isplac emen t Boundar y Condition, Y-D isplac emen t Boundar y Condition, Z-D isplac emen t Boundar y Condition contains a dr op-do wn list of metho ds for calcula ting the displac emen t of the no des in tha t par ticular direction: •Stress F ree specifies tha t the displac emen t is not aff ected b y str ess loads fr om the fluid flo w. •Node X- ,Node Y-, and (f or 3D c ases) Node Z-F orce specifies tha t the displac emen t results fr om a specified f orce applied on the no des, which is defined using the Node X- ,Node Y-, and (f or 3D cases) Node Z-F orce field . •Node X- ,Node Y-, and (f or 3D c ases) Node Z-D isplac emen t applies a sp ecified displac emen t on the no des, which is defined using the X-,Y-, and (f or 3D c ases) Z-D isplac emen t field . 3563Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Boundar y Conditions Task P age•Face Pressur e specifies tha t the displac emen t results fr om a sp ecified pr essur e load on the fac es, which is defined using the Face Pressur e field . •Intrinsic FSI specifies tha t the displac emen t results fr om pr essur e loads e xerted b y the fluid flo w on the fac es. Note tha t this selec tion is only a vailable f or a z one tha t is par t of a w all / w all-shado w pair. 47.8.23. Periodic C onditions D ialo g Box The Periodic C onditions dialo g box allo ws you t o set par amet ers tha t define fully-de velop ed p eriodic flow and hea t transf er. See User Inputs f or the P ressur e-Based S olver (p.1208 ) and Using P eriodic H eat Transf er (p.1569 ) for details . (This dialo g box is a vailable only when the pr essur e-based solv er is used; it is not a vailable f or the densit y-based c oupled solv ers.) Controls Specify M ass F low enables the sp ecific ation of the mass flo w rate. Specify P ressur e Gradien t enables the sp ecific ation of the pr essur e gr adien t. Mass F low R ate specifies the mass flo w rate.This it em will not b e available if y ou selec ted the Specify P ressur e Gradien t option. Imp ortant For axisymmetr ic pr oblems , the mass flo w rate is p er radians . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3564Task P age R eference GuidePressur e Gradien t specifies the pr essur e gr adien t ( in Equa tion 1.22 in the Theor y Guide ). Upstr eam Bulk Temp erature sets the inlet bulk t emp erature for p eriodic hea t transf er calcula tions . Flow D irection sets the dir ection of the p eriodic flo w.The dir ection v ector must b e par allel t o the p eriodic tr ansla tion direction or its opp osite. Relaxa tion F actor sets the under-r elaxa tion fac tor tha t controls c onvergenc e of the it eration pr ocess descr ibed in Setting Paramet ers f or the C alcula tion of β (p.1209 ) for sp ecified mass flo w. Numb er of I terations sets the numb er of subit erations done on the c orrection of in the pr essur e correction equa tion f or specified mass flo w. See Setting P aramet ers f or the C alcula tion of β (p.1209 ) for details . Update updates the Pressur e Gradien t field with the cur rent value . 47.9. Overset In terfaces Task P age The Overset In terfaces task page allo ws you t o cr eate overset in terfaces. For additional inf ormation about o verset in terfaces, see Overset M eshes (p.766). 3565Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Overset In terfaces Task P ageControls Create/Edit... displa ys the Create/Edit O verset In terfaces D ialog Box (p.3566 ). Preview M esh M otion... displa ys the Mesh M otion D ialog Box (p.3599 ). 47.9.1. Create/Edit O verset In terfaces D ialo g Box The Create/Edit O verset In terfaces dialo g box allo ws you t o cr eate and delet e overset in terfaces. For additional inf ormation, see Overset M eshes (p.766). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3566Task P age R eference GuideOverset In terface contains a t ext en try box wher e you must sp ecify the name of the o verset in terface. Below is a list of all existing o verset in terfaces. Back ground Z ones lists all of the back ground z ones a vailable f or selec tion when cr eating an o verset in terface. Multiple back ground z ones c an b e par t of an o verset in terface; however, a back ground z one c annot b e part of multiple o verset in terfaces. It is acc eptable t o ha ve an in terface with only c omp onen t zones and no back ground z ones . Comp onen t Zones lists all of the c omp onen t zones a vailable f or selec tion when cr eating of an o verset in terface. Multiple comp onen ts can b e par t of an o verset in terface; however, a comp onen t zone c annot b e par t of multiple overset in terfaces. Create creates an o verset in terface using the name in the Overset In terface text box and the z ones selec ted under Back ground Z ones and Comp onen t Zones . Note tha t grid pr iorities , if requir ed, are added t o the interface after it is cr eated, using the t ext command define/overset-interfaces/grid-prior- ities . Delet e delet es the selec ted Overset In terface. Delet e All delet es all o verset in terfaces in the domain. List prints zonal inf ormation and gr id pr iorities f or the selec ted Overset In terface. 47.10. Dynamic M esh Task P age The Dynamic M esh task page allo ws you t o define the all the par amet ers f or mo deling a d ynamic mesh model. See Setting D ynamic M esh M odeling P aramet ers (p.1266 ) for details ab out using the it ems b elow. 3567Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dynamic M esh Task P ageControls Dynamic M esh enables the d ynamic mesh mo del and ac tivates the c ontrols in the task page . Mesh M etho ds contains options t o sp ecify the mesh up date metho d(s). Smoothing enables mesh smo othing . See Smoothing M etho ds (p.1268 ) for details ab out the smo othing metho ds available . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3568Task P age R eference GuideLayering enables the d ynamic la yering metho d tha t can b e used t o add or r emo ve layers of c ells adjac ent to a moving b oundar y based on the heigh t of the la yer adjac ent to the mo ving sur face in pr isma tic mesh zones . See Dynamic La yering (p.1285 ) for details . Remeshing enables the lo cal or z onal r emeshing metho ds. In lo cal remeshing , the c ells tha t viola te the sk ewness or siz e criteria ar e agglomer ated and lo cally r emeshed; see Local Remeshing M etho d (p.1292 ) for fur ther details . In z onal r emeshing , the c omplet e cell z one (including the b oundar y zones) is r emeshed; see CutCell Z one R emeshing M etho d (p.1304 ) for fur ther details . Settings ... displa ys the Mesh M etho d Settings D ialog Box (p.3570 ) in which y ou c an sp ecify settings f or the Smoothing , Layering, and R emeshing metho ds. Options contains options t o sp ecify sp ecializ ed d ynamic mesh mo dels . In-C ylinder enables the in-c ylinder mo del. See In-C ylinder S ettings (p.1313 ) for mor e inf ormation. Six DOF enables the six degr ees of fr eedom (DOF) solv er. See Six DOF S olver Settings (p.1328 ) for mor e inf orma- tion. Implicit U pdate specifies tha t the mesh is up dated dur ing a time st ep (as opp osed t o just a t the b eginning of a time step). See Implicit U pdate Settings (p.1332 ) for mor e inf ormation. Contact Detection enables c ontact det ection. See Contact Detection S ettings (p.1334 ) for mor e inf ormation. Settings ... opens the Options D ialog Box (p.3575 ), wher e you c an set the par amet ers f or the options tha t are enabled in the Options group b ox. Events... displa ys the Dynamic M esh E vents D ialog Box (p.3584 ). Dynamic M esh Z ones displa ys a list of d ynamic mesh z ones . Create/Edit... displa ys the Dynamic M esh Z ones D ialog Box (p.3587 ). Delet e remo ves the selec ted d ynamic z one(s) fr om the Dynamic M esh Z ones list. Delet e All remo ves all d ynamic z ones fr om the Dynamic M esh Z ones list. Displa y Zone M otion... displa ys the Zone M otion D ialog Box (p.3598 ). 3569Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dynamic M esh Task P agePreview M esh M otion... displa ys the Mesh M otion D ialog Box (p.3599 ). For additional inf ormation, see the f ollowing sec tions: 47.10.1. Mesh M etho d Settings D ialog Box 47.10.2. Mesh S moothing P aramet ers D ialog Box 47.10.3. Mesh Sc ale Inf o Dialog Box 47.10.4. Options D ialog Box 47.10.5. In-C ylinder Output C ontrols D ialog Box 47.10.6. Six DOF P roperties D ialog Box 47.10.7. Flow Controls D ialog Box 47.10.8. Dynamic M esh E vents D ialog Box 47.10.9. Define E vent Dialog Box 47.10.10. Events Preview D ialog Box 47.10.11. Dynamic M esh Z ones D ialog Box 47.10.12. Orientation C alcula tor D ialog Box 47.10.13. Infla tion S ettings D ialog Box 47.10.14. CutCell B oundar y Zones Inf o Dialog Box 47.10.15. Zone Sc ale Inf o Dialog Box 47.10.16. Zone M otion D ialog Box 47.10.17. Mesh M otion D ialog Box 47.10.18. Autosave Case D uring M esh M otion P review D ialog Box 47.10.1. Mesh M etho d Settings D ialo g Box The Mesh M etho d Settings dialo g box allo ws you t o apply settings f or the smo othing , layering, or remeshing metho ds. Controls Smoothing contains par amet ers t o be sp ecified f or the smo othing mesh up date metho d. Metho d allows you t o sp ecify the smo othing metho d. Spring/L aplac e/Boundar y Layer specifies tha t the smo othing metho d is spr ing based , or appr opriate for the Laplacian smo othing metho d (for 2.5D r emeshing) or the b oundar y layer smo othing metho d. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3570Task P age R eference GuideDiffusion selec ts the diffusion-based smo othing metho d. Linear ly E lastic S olid selec ts smo othing based on the equa tions f or a linear ly elastic solid . Advanc ed... opens the Mesh S moothing P aramet ers D ialog Box (p.3573 ), in which y ou c an define the settings f or the selec ted smo othing Metho d. Layering contains par amet ers t o be sp ecified f or the la yering mesh up date metho d. Options specifies the cr iteria for splitting or c ollapsing c ell la yers. Heigh t Based specifies tha t the c ell la yers ar e split or mer ged based on heigh t. Ratio B ased specifies tha t the c ell la yers ar e split or mer ged based on r atios. Split F actor specifies the v alue of in Equa tion 11.15 (p.1286 ). It controls the heigh t or r atio a t which the c ells ar e split. Collapse F actor specifies the v alue of in Equa tion 11.16 (p.1287 ). It controls the heigh t or r atio a t which the c ells ar e collapsed and mer ged in to the ne xt layer. Remeshing contains par amet ers t o be sp ecified f or the r emeshing mesh up date metho d. Remeshing M etho ds contain options tha t control remeshing . Local C ell allows you t o remesh def orming b oundar y cells. Local F ace allows you t o remesh def orming b oundar y fac es.This option is a vailable f or 3D c ases . Region F ace allows you t o remesh a r egion. CutC ell Z one allows you t o replac e an en tire cell z one with a pr edominan tly C artesian mesh. This option is only available f or 3D c ases . Note tha t the par amet ers tha t control this r emeshing metho d ar e set in the Dynamic M esh Z ones dialo g box. See Using the C utCell Z one R emeshing M etho d (p.1306 ) for mor e inf ormation. 2.5D enables the 2.5D mo del. This option is only a vailable f or 3D c ases . See Using the 2.5D M odel (p.1309 ) for mor e inf ormation. 3571Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dynamic M esh Task P ageParamet ers contains par amet ers tha t control remeshing f or all of the r emeshing metho ds e xcept f or CutC ell Zone . Minimum L ength Sc ale specifies the lo wer limit of c ell siz e below which the c ells ar e mar ked f or remeshing . Maximum L ength Sc ale specifies the upp er limit of c ell siz e ab ove which the c ells ar e mar ked f or remeshing . Maximum C ell S kewness specifies the desir ed maximum sk ewness f or the mesh. Maximum F ace Skewness specifies the desir ed maximum sk ewness f or the sur face mesh. This option is ac tive, when Local Face is selec ted under Remeshing M etho ds. Size Remeshing In terval specifies the in terval in time st eps f or remeshing based on the ab ove siz e criteria only . Marking of cells based on sk ewness o ccurs aut oma tically a t every time st ep when Remeshing is enabled . Mesh Sc ale Inf o... opens the Mesh Sc ale Inf o Dialog Box (p.3574 ), in which y ou c an view the sta tistics of the mesh, such as the minimum and maximum length sc ale v alues and the maximum c ell and fac e sk ewness values . Default sets the fields in the Paramet ers group b ox to values tha t represen t a r easonable star ting p oint for y our par ticular mesh, as det ermined b y ANSY S Fluen t. After execution, the Default butt on becomes the Reset butt on. Reset resets the fields in the Paramet ers group b ox to the pr ior v alues (tha t is, those displa yed a t the momen t the Default butt on w as click ed). After execution, the Reset butt on b ecomes the Default butt on. Sizing Options contains par amet ers tha t control the sizing func tion. Sizing F unc tion allows you t o enable or disable the sizing func tion. Resolution sets the r esolution f or the sizing func tion. See Setting D ynamic M esh M odeling P aramet ers (p.1266 ) for mor e inf ormation. Variation specifies the v alue of in Equa tion 11.22 (p.1298 ). Rate specifies the v alue of in Equa tion 11.23 (p.1298 ). Default sets the sizing func tion par amet ers t o the default v alues , as det ermined b y ANSY S Fluen t based on the cur rent mesh. After execution, the Default butt on b ecomes the Reset butt on. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3572Task P age R eference GuideReset resets the sizing func tion par amet ers t o the pr ior v alues (tha t is, those displa yed a t the momen t the Default butt on w as click ed). After execution, the Reset butt on b ecomes the Default butt on. 47.10.2. Mesh S moothing P aramet ers D ialo g Box The Mesh S moothing P aramet ers dialo g box allo ws you t o define the settings f or the smo othing metho d selec ted in the Smoothing tab of the Mesh M etho d Settings D ialog Box (p.3570 ). Controls Spring C onstan t Factor controls the spr ing stiffness . Convergenc e Toler anc e controls the smo othing c onvergenc e. Maximum N umb er of I terations specifies the maximum numb er of it erations tha t will b e attempt ed. Elemen ts controls the elemen ts wher e spr ing-based smo othing is applied . Tet in Tet Z ones (3D only) sp ecifies tha t only c ell z ones with all t etrahedr al elemen ts get smo othed . Tet in M ixed Z ones (3D only) sp ecifies tha t tetrahedr al elemen ts in mix ed elemen t zones get smo othed . Tri in Tri Zones (2D only) sp ecifies tha t only c ell z ones with all tr iangular elemen ts get smo othed . Tri in M ixed Z ones (2D only) sp ecifies tha t triangular elemen ts in mix ed elemen t zones get smo othed . 3573Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dynamic M esh Task P ageAll specifies tha t all elemen t types get smo othed . Laplac e Node Relaxa tion specifies ho w the up date of the no de p ositions is r elax ed on b oundar ies wher e ther e is Laplacian smo othing . Verb osit y specifies whether t o pr int smo othing r esiduals t o the c onsole . Setting this t o 1 ensur es tha t such r esiduals are pr inted, wher eas the default v alue of 0 suppr esses such output. Diffusion F unc tion specifies whether the diffusion c oefficien t is a func tion of the Boundar y Distanc e (Equa tion 11.3 (p.1270 )) or the Cell Volume (Equa tion 11.4 (p.1270 )).This dr op-do wn list is only a vailable f or diffusion-based smo othing . Diffusion P aramet er specifies in Equa tion 11.3 (p.1270 ) or Equa tion 11.4 (p.1270 ), dep ending on the selec ted Diffusion F unc tion . This numb er-en try box is only a vailable f or diffusion-based smo othing . AMG S tabiliza tion selec ts the algebr aic multigr id (AMG) stabiliza tion metho d used b y the linear solv er to perform mesh smo othing c alcula tions .This dr op-do wn list is only a vailable f or smo othing based on diffusion (when using the finit e elemen t metho d) or the linear ly elastic solid mo del. Rela tive Convergenc e Toler anc e specifies the r elative residual t oler ance for smo othing based on diffusion or the linear ly elastic solid model. Gener aliz ed B oundar y Distanc e M etho d is an option tha t is a vailable when y ou ha ve selec ted Boundar y Distanc e for the Diffusion F unc tion , and it allo ws you t o use of a “gener alized” boundar y distanc e for the diffusion c oefficien t calcula tion. When this option is enabled , the c alcula tion uses the nor maliz ed distanc e to the near est b oundar y tha t is not declar ed as def orming , regar dless of t ype; when it is disabled , only w all b oundar ies ar e consider ed. Smoothing F rom Ref erenc e Position enables smo othing fr om a r eference position. Such smo othing ma y pr oduce gr eater mesh qualit y consist- ency for sta tionar y or mo ving meshes with p eriodic or quasi-p eriodic motion. It is a vailable when the smo othing metho d is based on diffusion or the linear ly elastic solid mo del; it is not a vailable with la yering, remeshing , and/or d ynamic adaption. Poisson ’s Ratio specifies the linear ly elastic solid ma terial pr operty in Equa tion 11.12 (p.1280 ).This numb er-en try box is only a vailable f or smo othing based on the linear ly elastic solid mo del. 47.10.3. Mesh Sc ale Inf o Dialo g Box The Mesh Sc ale Inf o dialo g box allo ws you t o insp ect the v alues of minimum and maximum length scale and maximum c ell/fac e sk ewness in a mesh. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3574Task P age R eference GuideControls Minimum L ength Sc ale displa ys the minimum length sc ale in the mesh. Maximum L ength Sc ale displa ys the maximum length sc ale in the mesh. Maximum C ell S kewness displa ys the maximum c ell sk ewness in the z one . Maximum F ace Skewness displa ys the maximum c ell sk ewness in the sur face mesh. 47.10.4. Options D ialo g Box The Options dialo g box allo ws you t o set the par amet ers f or the options a vailable in the Options group b ox of the Dynamic M esh task page . 3575Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dynamic M esh Task P ageControls In-C ylinder contains par amet ers t o be sp ecified f or the in-c ylinder mo del. See In-C ylinder S ettings (p.1313 ) for mor e information. Crank S haft Speed specifies the sp eed of the cr ank shaf t. Starting C rank A ngle specifies the star ting cr ank angle . Crank P eriod specifies the cr ank p eriod. Crank A ngle S tep S ize specifies the cr ank angle st ep siz e used t o det ermine the time st ep siz e to ad vance the solution. Crank R adius specifies the cr ank r adius t o calcula te the pist on lo cation. Piston P in O ffset specifies the p erpendicular off set of the pist on pin fr om the plane defined b y the cr ank shaf t axis and the dir ection of motion of the pist on.The sign of this v alue is p ositiv e if t op-dead-c enter (TDC) o ccurs prior t o a cr ank angle of 0°. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3576Task P age R eference GuideConnec ting Ro d Length specifies the length of the c onnec ting r od. Piston S troke Cutoff specifies the pist on str oke cut off used t o control the onset of la yering in the c ylinder chamb er. Minimum Valve Lif t specifies the minimum v alve lift. Write In-C ylinder Output enables or disables the wr iting of in-c ylinder sp ecific output par amet ers.When this option is enabled , the Output C ontrols... butt on b ecomes ac tive. Output C ontrols... displa ys the In-C ylinder Output C ontrols D ialog Box (p.3578 ) and is a vailable only af ter the Write In- Cylinder Output option is enabled . Six DOF contains par amet ers t o be sp ecified f or the six degr ees of fr eedom (DOF) solv er. See Six DOF S olver Set- tings (p.1328 ) for mor e inf ormation. Six DOF P roperties displa ys a list of defined sets of six DOF pr operties. Create/Edit... opens the Six DOF P roperties D ialog Box (p.3580 ). Delet e remo ves the selec ted set of six DOF pr operties fr om the Six DOF P roperties list. Delet e All remo ves all sets of six DOF pr operties fr om the Six DOF P roperties list. Gravita tional A cceler ation contains the t ext en try boxes for gr avitational acc eleration in X, Y, and Z dir ections . X,Y, Z specifies the gr avitational acc eleration in X, Y, and Z dir ections r espectively. Write M otion Hist ory allows you t o keep tr ack of an objec t’s motion hist ory. File N ame allows you t o sp ecify a file name f or sa ving the objec t’s motion hist ory. Implicit U pdate contains par amet ers t o be sp ecified f or implicit mesh up dating . See Implicit U pdate Settings (p.1332 ) for mor e inf ormation. Update In terval allows you t o sp ecify the fr equenc y in it erations a t which the mesh will b e up dated within a time step. 3577Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dynamic M esh Task P ageMotion Relaxa tion allows you t o set a v alue (within the r ange of 0 t o 1) f or in Equa tion 11.29 (p.1334 ), which defines the r elaxa tion of the motion (tha t is, displac emen t of the no des) dur ing the mesh up date. Residual C riteria allows you t o set the r elative residual thr eshold tha t is used t o check the motion c onvergenc e. Contact Detection contains par amet ers t o be sp ecified f or contact det ection. See Contact Detection S ettings (p.1334 ) for mor e information. Face Zones allows you t o selec t the fac e zones tha t will b e involved in c ontact det ection. Proximit y Threshold allows you t o set the thr eshold b elow which the user-defined func tion f or contact det ection will b e invoked. UDF allows you t o sp ecify the user-defined func tion tha t will b e invoked when c ontact has b een det ected. Flow C ontrol allows you t o indic ate whether flo w control zones ar e going t o be used in the c ontact det ection process. Controls... opens the Flow Controls D ialog Box (p.3583 ) wher e you c an mak e additional flo w control settings . 47.10.5. In-C ylinder Output C ontrols D ialo g Box The In-C ylinder Output C ontrols dialo g box contains par amet ers tha t control the output f or the in- cylinder mo del. See In-C ylinder S ettings (p.1313 ) for mor e inf ormation. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3578Task P age R eference GuideControls In-C ylinder D ata Write Frequenc y represen ts an in teger en try sp ecifying the in terval in numb er of time-st eps. Make sur e tha t a v alue other than 0 is used f or the fr equenc y, in or der t o allo w you t o complet e your setup . Swirl Center M etho d contains a dr op-do wn list tha t allo ws you t o selec t the metho d to calcula te the swir l center.The list c ontains center of gr avity and fixed, with center of gr avity being the default v alue . center of gr avity calcula tes the swir l center inside the c ode and is used as the c enter of gr avity of the chosen c ell z ones . fixed enables y ou t o sp ecify a swir l center in the X,Y, and Z entry fields b elow the dr op-do wn list. In addition t o these t wo options , you c an chose t o use y our o wn Compiled user-defined func tion to calcula te the swir l center. For details on using a d ynamic mesh UDF , see the separ ate Fluen t Customiza tion M anual . Cell Z ones is a list tha t displa ys the names of all e xisting c ell z ones in the c ase files .You c an selec t only the z ones relevant for the swir l and tumble c alcula tions . Swirl Axis specifies the swir l axis with thr ee en tries f or the dir ectional c omp onen ts. By default ,X,Y,Z= 0,1,0. 3579Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dynamic M esh Task P ageTumble A xis specifies the dir ectional c omp onen ts of Tumble A xis in X,Y,Z directions . By default ,X,Y,Z = 0,0,1.This applies only in 3D . Cross Tumble A xis specifies the dir ectional c omp onen ts of Cross Tumble A xis in X,Y,Z directions . By default ,X,Y,Z = 1, 0,0.This applies only in 3D . File N ame specifies the name of the In-C ylinder output file . By default , the file name c ontains the name of the c ase file app ended with a .txt extension. 47.10.6. Six DOF P roperties D ialo g Box The Six DOF P roperties dialo g box allo ws you t o define a set of pr operties f or a r igid b ody dynamic objec t tha t uses the Six DOF solv er.The set of pr operties tha t you cr eate can then b e selec ted in the Six DOF UDF/P roperties drop-do wn in the Dynamic M esh Z ones D ialog Box (p.3587 ) for the z ones tha t mak e up the objec t. See Setting R igid B ody Motion A ttribut es for the S ix DOF S olver (p.1330 ) and Rigid Body Motion (p.1349 ) for mor e inf ormation. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3580Task P age R eference GuideControls Name specifies the name of the set of pr operties, which will b e selec table in the Six DOF UDF/P roperties drop- down in the Dynamic M esh Z ones D ialog Box (p.3587 ). Mass defines the mass of the r igid b ody dynamic objec t. One DOF Transla tion specifies tha t the d ynamic objec t will only under go one DOF tr ansla tion. One DOF Rota tion specifies tha t the d ynamic objec t will only under go one DOF r otation. One DOF contains settings tha t define the one DOF tr ansla tion or r otation. 3581Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dynamic M esh Task P ageDirection defines the v ector along which the objec t will b e allo wed t o transla te. Axis defines the c omp onen ts of the axis of r otation. Note tha t for 2D c ases , the axis will b e either the positiv e or nega tive z direction, dep ending on the sign of the v alue y ou en ter for Z. Center of Rota tion defines the p oint ab out which the objec t rotates. Spring contains settings tha t define an optional H ooke's la w spr ing tha t can e xert forces / t orques on the objec t. It is a c ompr ession / e xtension spr ing f or tr ansla tions , and it is a t orsion spr ing f or rotations . Preload defines a spr ing load tha t is c onstan tly applied t o the objec t, in addition t o the loading r esulting from the spr ing Constan t.The Preload can b e a p ositiv e or nega tive value , and is defined r elative to the Direction (for tr ansla tion) or the Axis (for rotation). Constan t defines the spr ing c onstan t / rate. Constr ained specifies tha t the r ange of motion of the objec t is limit ed, as defined b y the settings in the Referenc e Point group b ox (for tr ansla tion) or the Referenc e Angle group b ox (for rotation). Referenc e Point contains settings tha t define the limits of the objec t's tr ansla tion when the Constr ained option is enabled . Location assigns a c oordina te value t o a p oint located on the objec t in its initial p osition; the Minimum and Maximum coordina tes ar e then defined r elative to this v alue along the Direction vector, in order t o establish the limits of tr ansla tion. Minimum defines the lo wer extent of the c onstr ained tr ansla tion along the Direction vector, relative to the Location . Maximum defines the upp er extent of the c onstr ained tr ansla tion along the Direction vector, relative to the Location . Referenc e Angle contains settings tha t define the limits of the objec t's rotation when the Constr ained option is enabled . Value assigns an angular c oordina te value t o the or ientation of the objec t in its initial p osition; the Minimum and Maximum angles ar e then defined r elative to this or ientation ab out the axis of rotation, in or der t o establish the limits of r otation. Minimum defines the lo wer extent of the c onstr ained r otation ab out the axis of r otation, relative to the Value . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3582Task P age R eference GuideMaximum defines the upp er extent of the c onstr ained r otation ab out the axis of r otation, relative to the Value . Momen t of Iner tia defines the momen t of iner tia for the r igid b ody dynamic objec t tha t under goes one degr ee of fr eedom (DOF) r otation. Iner tia Tensor defines the c omp onen ts of the iner tia t ensor f or the objec t dur ing six DOF motion. Note tha t the v alues are relative to the Center of G ravity and Rigid B ody Or ientation settings defined in the Dynamic M esh Zones D ialog Box (p.3587 ); the la tter settings allo w you t o use a c oordina te sy stem tha t is lo cal (rather than global), if tha t is mor e convenien t. 47.10.7. Flow C ontrols D ialo g Box The Flow C ontrols dialo g box allo ws you t o sp ecify flo w control cell z ones tha t are going t o be used in the c ontact det ection pr ocess. See Contact Detection S ettings (p.1334 ) for mor e inf ormation. Controls Cell Z ones is a list tha t displa ys the names of all e xisting c ell z ones . Settings contains flo w control zone settings . Flow C ontrol Z one allows you t o sp ecify a name f or the flo w control zone . 3583Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dynamic M esh Task P ageCreate Zone allows you t o create a new flo w control zone of the sp ecified name . Delet e Zone allows you t o delet e the selec ted flo w zone . 47.10.8. Dynamic M esh E vents D ialo g Box The Dynamic M esh E vents dialo g box is a vailable t o control the timing of sp ecific e vents dur ing the course of the simula tion. See Defining D ynamic M esh E vents (p.1336 ) for details . Controls Numb er of E vents specifies the numb er of e vents to be defined . On enables the c orresponding e vent. Name specifies the name of the e vent. At Crank A ngle specifies the angular lo cation of the cr ank a t which the e vent should o ccur .This option app ears f or in- cylinder flo ws. At Time specifies the time (in sec onds) a t which y ou w ant the e vent to occur .This option app ears f or non-in-c yl- inder flo ws. Define ... opens the Define E vent Dialog Box (p.3585 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3584Task P age R eference GuideRead ... opens The S elec t File D ialog Box (p.569). Write... opens The S elec t File D ialog Box (p.569). Preview... opens the Events Preview D ialog Box (p.3587 ). 47.10.9. Define E vent Dialo g Box The Define E vent dialo g box allo ws you t o define e vents. Controls Name contains the name of the e vent to be defined . Type specifies the t ype of e vent.You c an cho ose the t ype of e vent from the dr op-do wn list. These e vent types and their definitions ar e descr ibed in Events (p.1340 ). Definition contains the input par amet ers c orresponding t o the t ype of e vent selec ted under Type. Zone contains a selec table list of the z ones .The selec tion sp ecifies the name of the z one(s) t o be changed . This it em will app ear only f or the Change Z one Type event. New Z one Type specifies the t ype of z one t o which an e xisting z one must b e changed .This it em will app ear only f or the Change Z one Type event. From Z one specifies the name of the z one fr om which the b oundar y condition is t o be copied .This it em will app ear only f or the Copy Zone BC event. 3585Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dynamic M esh Task P ageTo Zone(s) specifies the name of the z one t o which the b oundar y condition is t o be copied .This it em will app ear only f or the Copy Zone BC event. Zone(s) contains a selec table list of the z ones .The selec tion sp ecifies the name of the z one t o be ac tivated/de- activated.This it em will app ear only f or the Activate Cell Z one and Deac tivate Cell Z one events. Interface Name contains the name of the in terface to be created or delet ed.This it em will app ear only f or the Create Sliding In terface and Delet e Sliding In terface events. Interface Zone 1, Interface Zone 2 specifies the t wo zones on either side of the in terface to be created.This it em will app ear only f or the Create Sliding In terface event. Wall 1 M otion, Wall 2 M otion specifies the d ynamic z ones whose motion c an b e copied f or the z ones sp ecified under Interface Zone 1 and Interface Zone 2 .This it em will app ear only f or the Create Sliding In terface event. Attribut e allows you t o selec t the r elevant motion a ttribut e.This it em will app ear only f or the Change M otion Attribut e event. Status allows you t o enable or disable the motion a ttribut e.This it em will app ear only f or the Change M otion Attribut e event. Dynamic M esh Z ones contains a list of d ynamic z ones .This it em will app ear only f or the Change M otion A ttribut e event. Crank A ngle S tep S ize specifies the new ph ysical time st ep v alue in degr ees.This it em will app ear only f or the Change Time Step S ize event. Base D ynamic Z one specifies the z one fr om which the la yer of c ells is t o be created.This it em will app ear only f or the Inser t Boundar y Layer and Remo ve Boundar y Layer event. Side D ynamic Z one represen ts the def orming fac e zone adjac ent to the Base D ynamic Z one before the la yer is inser ted. This it em will app ear only f or the Inser t Boundar y Layer event. Internal Z one 1 N ame , Internal Z one 2 N ame specifies the name of the new in ternal z ones . Time S tep S ize allows you t o change the time st ep siz e of the e vent.This it em will app ear only f or the Change Time Step S ize event. Under-Relaxa tion F actors allows you t o sp ecify the under-r elaxa tion fac tors f or the selec ted e vent.This it em will app ear only for the Change U nder-Relaxa tion F actors event. See Setting U nder-R elaxa tion F actors (p.2573 ) for details . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3586Task P age R eference GuideAdjac ent Dynamic F ace Zone allows you t o selec t the d ynamic fac e zone adjac ent to the lo cation of the c ell la yer to be inser ted (or delet ed). You c an selec t the r equir ed z one fr om the dr op-do wn list. Direction P aramet er is the dir ection with r espect to the selec ted d ynamic fac e zone a la yer of c ells is r emo ved or added . Command specifies the ser ies of t ext / Scheme c ommands or the macr o to be execut ed dur ing the simula tion. This it em will app ear only f or the Execut e Command event. 47.10.10. Events P review D ialo g Box The Events P review dialo g box allo ws you t o pla y the e vents to check tha t the y are defined c orrectly. Controls Start Crank A ngle specifies the cr ank angle a t which y ou w ant to star t the pr eview (f or in-c ylinder flo ws). Start Time specifies the time a t which y ou w ant to star t the pr eview (f or non-in-c ylinder flo ws). End C rank A ngle specifies the cr ank angle a t which y ou w ant to end the pr eview (f or in-c ylinder flo ws). End Time specifies the time a t which y ou w ant to end the pr eview (f or non-in-c ylinder flo ws). Incr emen t specifies the siz e of the st ep t o tak e dur ing the pr eview . Preview plays back the e vents at the cr ank angle sp ecified f or each e vent and r eports when each e vent occurs in the t ext (console) windo w. 47.10.11. Dynamic M esh Z ones D ialo g Box The Dynamic M esh Z ones dialo g box allo ws you t o sp ecify the motion of the d ynamic z ones in y our model. See Specifying the M otion of D ynamic Z ones (p.1345 ) for details . 3587Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dynamic M esh Task P ageControls Zone N ames contains the names of the z ones in the mo del. Type contains the t ypes of motion tha t can b e sp ecified f or a d ynamic z one . Stationar y explicitly declar es the z one as sta tionar y, so tha t the no des on this z one ar e excluded when up dating the no de p ositions . See Specifying the M otion of D ynamic Z ones (p.1345 ) for mor e inf ormation. Rigid B ody specifies the z one as ha ving a r igid-b ody motion. Deforming specifies the z one as def orming . User-D efined enables y ou t o sp ecify a user-defined z one motion. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3588Task P age R eference GuideSystem C oupling allows the z one t o be involved in a sy stem c oupling simula tion wher e the motion is defined b y the applic ation tha t ANSY S Fluen t is c oupled with on this z one (see the Fluen t in Workbench U ser's G uide and the System C oupling G uide for mor e details). Onc e enabled , the Solver Options tab c an b e used to help achie ve convergenc e for sy stem c oupling c ases wher e the ph ysics is str ongly c oupled . If a dynamic mesh z one of the t ype System C oupling exists , and ANSY S Fluen t is not in volved in a sy stem coupling simula tion, then this z one t ype behaves in the same w ay as a sta tionar y zone . Intrinsic FSI specifies tha t a w all z one b etween a fluid and solid c ell z one def orms acc ording t o the def ormation of the adjac ent solid z one as par t of a t wo-w ay intrinsic fluid-str ucture interaction (FSI) simula tion. Note tha t this t ype can only b e used f or the side of a t wo-sided w all (tha t is, the w all or w all-shado w) that is immedia tely adjac ent to the fluid c ell z one (as indic ated b y the Adjac ent Cell Z one field in the Wall dialo g box).This option is only a vailable when a mo del is selec ted in the Structural M odel Dialog Box (p.3378 ). Dynamic M esh Z ones lists all of the d ynamic z ones in the c ase. Motion A ttribut es contains par amet ers t o sp ecify the motion a ttribut es for a r igid-b ody-motion z one and a user-defined- motion z one . Motion/UDF P rofile allows you t o define the motion of the r igid b ody zone b y selec ting a pr ofile or user-defined func tion from the dr op-do wn list. See Profiles (p.1051 ) and Solid-B ody Kinema tics (p.1365 ) for inf ormation on profiles , and see the Fluen t Customiza tion M anual for inf ormation on user-defined func tions . Six DOF UDF/P roperties allows you t o define the motion of a r igid b ody zone b y selec ting a pr ofile , user-defined func tion, or set of six DOF pr operties (cr eated using the Six DOF P roperties D ialog Box (p.3580 )) from the dr op- down list. This option is a vailable only when On is enabled in the Six DOF group b ox. Six DOF contains par amet ers f or the Six DOF solv er. On enables the use of the Six DOF solv er. Passiv e (if enabled) do es not tak e forces and momen ts on the z one in to consider ation. Center of G ravity Location specifies the initial v alues of the c oordina tes for the lo cation of the c enter of gr avity of the selec ted zone .This it em will app ear only if the motion Type is Rigid B ody and In-C ylinder is not enabled in the Dynamic M esh task page . After calcula ting , ANSY S Fluen t up dates these fields , allo wing y ou t o keep tr ack of the objec t's cur rent location. Motion Options provides a Rela tive M otion option, which allo ws you t o sp ecify tha t the motion of the d ynamic z one is relative to another pr e-defined r igid b ody zone .This gr oup b ox will only app ear if the Type is Rigid Body or User-D efined ; for the la tter, the Rela tive Zone must b e a c ell z one . 3589Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dynamic M esh Task P ageRigid B ody Or ientation specifies the initial v alues tha t define the or ientation of the r igid b ody of the selec ted z one .This it em will app ear only if the motion Type is Rigid B ody and In-C ylinder is not enabled in the Dynamic Mesh task page . After calcula ting , ANSY S Fluen t up dates these fields , allo wing y ou t o keep tr ack of the objec t's cur rent orientation. Center of G ravity Velocity specifies the v elocity of the c enter of gr avity with r espect to iner tia c oordina te sy stem. This option is available only if the Six DOF solv er is the selec ted mo del. Rigid B ody Angular Velocity specifies the angular v elocity of the r igid b ody with r espect to iner tia c oordina te sy stem. This option is available only if the Six DOF solv er is the selec ted mo del. Lift/Stroke contains the cur rent value of v alve lift or pist on str oke, which is aut oma tically up dated when y ou click Create.This it em will app ear only if In-C ylinder is enabled in the Dynamic M esh task page . Valve/Position A xis specifies the dir ection of the r eference axis of the v alves or pist on f or an in-c ylinder pr oblem. This item will app ear only if In-C ylinder is enabled in the Dynamic M esh task page . Mesh M otion UDF allows you t o selec t the user-defined func tion tha t defines the geometr y and motion of the z one . This it em will app ear only if the motion Type is User-D efined . Exclude M esh M otion in B oundar y Conditions allows you t o sp ecify tha t the b oundar y mesh motion should not b e included in the ph ysical boundar y conditions of tha t zone .This option is only a vailable f or non-p eriodic b oundar y zones . Geometr y Definition contains par amet ers t o define a def orming z one . Definition allows you t o selec t a geometr y definition t o pr ojec t no des of the def orming z one on. Available options are faceted,plane ,cylinder , and user-defined . Feature Options allows you t o pr eser ve features for 3D c ases on b oundar y zones of t ype Deforming or User-D efined . Such f eatures ma y be at the junc ture of diff erent boundar y zones , or the y ma y be on a single non- planar b oundar y zone . Feature Detection enables the det ection and pr eser vation of f eatures of a par ticular angular r ange . Feature Angle defines a thr eshold v alue in degr ees. For details on ho w this angle is defined , see Feature Detec- tion (p.1313 ). Point on P lane allows you t o sp ecify the p osition of a p oint on the plane .This it em will app ear only when y ou selec t plane for the Definition . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3590Task P age R eference GuidePlane N ormal allows you t o sp ecify the dir ection of the plane nor mal. This it em will app ear only when y ou selec t plane for the Definition . Cylinder R adius allows you t o sp ecify the r adius of the c ylinder .This it em will app ear only when y ou selec t cylinder for the Definition . Cylinder Or igin allows you t o sp ecify the lo cation of the c ylinder or igin. This it em will app ear only when y ou selec t cylinder for the Definition . Cylinder A xis allows you t o sp ecify the dir ection of the c ylinder axis .This it em will app ear only when y ou selec t cylinder for the Definition . Geometr y UDF allows you t o selec t a user-defined func tion f or a geometr y Definition . Meshing Options contains par amet ers f or v arious meshing options . Adjac ent Zone contains the name of the adjac ent zone tha t is in volved in lo cal remeshing or d ynamic la yering.This item will app ear only if the z one t ype is Stationar y,Rigid B ody,User-D efined , or Intrinsic FSI , and if the z one is not the b oundar y of a C utCell d ynamic c ell z one . Cell H eigh t allows you t o sp ecify the ideal heigh t of the adjac ent cells as either a c onstan t value or a c ompiled user-defined func tion. This it em will app ear only if the motion Type is Stationar y,Rigid B ody,User- Defined , or Intrinsic FSI , and if the z one is not the b oundar y of a C utCell d ynamic c ell z one . Deform A djac ent Boundar y Layer with Z one enables the smo othing of an adjac ent boundar y layer mesh. This option is not a vailable when Sta- tionar y or Deforming is selec ted in the Type list. Remeshing enables r emeshing f or a def orming z one , and allo ws you t o use the settings in the gr oup b ox below to sp ecify whether the global settings defined in the Remeshing tab of the Mesh M etho d Settings Dialog Box (p.3570 ) are applied t o this z one .The settings tha t are available in the gr oup b ox are based on whether y ou ar e defining a b oundar y zone or a c ell z one , and on the global r emeshing settings . Paramet ers provides r emeshing settings f or b oundar y zones or c ell z ones tha t are not C utCell z ones . Global S ettings allows you t o sp ecify tha t this def orming z one uses the settings y ou defined globally in the Remeshing tab of the Mesh M etho d Settings dialo g box.When this option is disabled , you can use the other settings under Paramet ers to define unique lo cal remeshing cr iteria. Minimum L ength Sc ale specifies the lo wer limit of c ell siz e below which the c ells ar e mar ked f or remeshing f or the zone . 3591Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dynamic M esh Task P ageMaximum L ength Sc ale specifies the upp er limit of c ell siz e ab ove which the c ells ar e mar ked f or remeshing f or the zone . Maximum S kewness specifies the desir ed v alue f or maximum sk ewness in the z one . Zone Sc ale Inf o... opens the Zone Sc ale Inf o Dialog Box (p.3597 ), in which y ou c an view the sta tistics of the z one , such as minimum, maximum, and a verage length sc ale v alues , as w ell as the maximum skewness . Options provides r emeshing options f or the z one . Region enables the r egion-based r emeshing metho d for b oundar y zones . Local enables the lo cal fac e remeshing metho d for b oundar y zones . CutC ell enables the C utCell z one r emeshing metho d for cell z ones . CutC ell Z one P aramet ers provides a set of global par amet ers used f or C utCell z one r emeshing .These settings will only app ear if the CutC ell option is enabled under Options . Maximum M esh S ize specifies the maximum mesh siz e of the C artesian C utCell mesh. Growth R ate specifies the default gr owth r ate used f or mesh r efinemen t by siz e func tions .This gr owth r ate is used dur ing r emeshing b y the mesh-based siz e func tions of all b oundar ies of the C utCell cell z one tha t are not defined as d ynamic mesh z ones . Minimum Or tho gonal Q ualit y specifies the minimum allo wable or thogonal qualit y for the c ell z one . CutCell remeshing will occur if the or thogonal qualit y for an y cell in the c ell z one dr ops b elow this v alue . Remeshing In terval specifies the in terval of time st eps a t which the c ell z one r emeshing will tak e plac e, even if the mesh qualit y has not det eriorated b elow the v alue en tered f or Minimum Or tho gonal Qualit y. Enter a v alue of 0 for the Remeshing In terval if you w ant the r emeshing t o occur only if ther e is insufficien t mesh qualit y. Infla tion L ayers allows you t o enable infla tion la yers on the C utCell c ell z one and sp ecify global infla tion paramet ers. Settings ... opens the Infla tion S ettings D ialog Box (p.3596 ), which allo ws you t o en ter the global infla tion paramet ers used b y default on all b oundar y zones . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3592Task P age R eference GuideZone Sc ale Inf o... opens the Zone Sc ale Inf o Dialog Box (p.3597 ), in which y ou c an view the sta tistics of the mesh, such as minimum, maximum, and a verage length sc ale v alues , as w ell as the maximum skewness . Boundar y Zones Inf o... opens the CutCell B oundar y Zones Inf o Dialog Box (p.3597 ), which lists all of the b oundar y zones f or the C utCell d ynamic c ell z one , along with the r emeshing and infla tion la yer par a- met ers. CutC ell B oundar y Zone P aramet ers provides a set of lo cal par amet ers used f or C utCell z one r emeshing .This gr oup b ox will only app ear if the z one is a b oundar y of a C utCell d ynamic c ell z one . Maximum M esh S ize specifies the maximum mesh siz e used b y the sof t siz e func tion. If a v alue of 0 is en tered, a mesh-based siz e func tion is used t o locally r efine the C artesian mesh near the b oundar y. Growth R ate specifies the lo cal gr owth r ate used b y the siz e func tion. Zonal Infla tion L ayer C ontrol allows you t o enable lo cal infla tion la yer control and sp ecify lo cal infla tion par amet ers.This option is only a vailable if Infla tion L ayers has b een enabled f or the C utCell d ynamic c ell z one . If Zonal Infla tion L ayer C ontrol is not enabled , then the global infla tion par amet ers sp ecified for the c ell z one ar e used . Settings ... opens the Infla tion S ettings D ialog Box (p.3596 ), which allo ws you t o en ter lo cal infla tion paramet ers f or the C utCell b oundar y zone . Zone Sc ale Inf o... opens the Zone Sc ale Inf o Dialog Box (p.3597 ), in which y ou c an view the sta tistics of the mesh, such as minimum, maximum, and a verage length sc ale v alues , as w ell as the maximum skewness . Smoothing enables smo othing f or a def orming z one , and allo ws you t o use the settings in the gr oup b ox below to sp ecify whether the global settings defined in the Smoothing tab of the Mesh M etho d Settings Dialog Box (p.3570 ) dialo g box and the Mesh S moothing P aramet ers D ialog Box (p.3573 ) are applied t o this z one .The settings tha t are available in the gr oup b ox are based on whether y ou ar e defining a boundar y zone or a c ell z one , and on the global smo othing settings . Elemen ts allows you t o sp ecify the elemen t types for which spr ing-based smo othing is used in this z one . This will only b e available if y ou ar e defining a c ell z one and the Spring/L aplac e/Boundar y Layer metho d has b een selec ted in the Smoothing tab of the Mesh M etho d Settings dialo g box. Global S ettings allows you t o sp ecify tha t this def orming z one smo oths the elemen t types y ou sp ecified globally in the Mesh S moothing P aramet ers D ialog Box (p.3573 ).When this option is disabled , you c an mak e a unique lo cal selec tion using the r adio butt ons b elow. 3593Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dynamic M esh Task P ageTet in Tet Z ones (3D only) sp ecifies tha t this z one will get smo othed only if it c onsists en tirely of t etrahedr al elemen ts. Tet in M ixed Z ones (3D only) sp ecifies tha t all t etrahedr al elemen ts in this z one should get smo othed . All other elemen ts in a mix ed elemen t zone will not under go smo othing . Tri in Tri Zones (2D only) sp ecifies tha t this z one will get smo othed only if it c onsists en tirely of tr iangular elemen ts. Tri in M ixed Z ones (2D only) sp ecifies tha t all tr iangular elemen ts in this z one should get smo othed . All other elemen ts in a mix ed elemen t zone will not under go smo othing . All specifies tha t all elemen t types in this z one will get smo othed . Metho ds allows you t o sp ecify the smo othing metho d for the z one .This is only a vailable if y ou ar e defining a boundar y zone and the Spring/L aplac e/Boundar y Layer metho d has b een selec ted in the Smoothing tab of the Mesh M etho d Settings dialo g box. Spring enables the spr ing-based smo othing metho d for this z one . Laplac e enables the Laplacian smo othing metho d for this z one . Remeshing M etho d provides settings f or lo cal fac e remeshing of the d ynamic z one .This gr oup b ox will app ear only f or boundar y zones , when the motion Type is User-D efined . Local enables lo cal fac e remeshing f or the d ynamic z one .This option is only a vailable when Local F ace is enabled in the Remeshing tab of the Mesh M etho d Settings D ialog Box (p.3570 ). Maximum S kewness is a field tha t, if revised (with a r easonable v alue), sets a maximum sk ewness f or the lo cal fac e remeshing of the d ynamic z one tha t is diff erent than the global v alue set in the Remeshing tab of the Mesh M etho d Settings D ialog Box (p.3570 ). Solver Options contains settings tha t ma y help c onvergenc e for b oundar y zones in c ases tha t involve str ong fluid- structure interaction (notably z ones under going r igid b ody motion with the six degr ees of fr eedom solv er, system c oupling motion, or t wo-w ay intrinsic FSI motion). See Solution S tabiliza tion f or D ynamic Mesh B oundar y Zones (p.1364 ) for mor e inf ormation. Solution S tabiliza tion enables/disables solution stabiliza tion settings f or b oundar y zones . Stabiliza tion P aramet ers contains options f or solution stabiliza tion settings . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3594Task P age R eference GuideScale F actor allows you t o set the sc ale fac tor used b y the selec ted Metho d for convergenc e stabiliza tion. Metho d Stabiliza tion is achie ved thr ough a b oundar y sour ce coefficien t introduced in the c ontinuit y equa tion. It is designed t o impr ove the diagonal dominanc e of the ma trix sy stem in the c ells ad- jacent to the b oundar y zone .Two metho ds for this b oundar y sour ce coefficien t are available: volume-based specifies tha t the diagonal en try of the linear ma trix sy stem c orresponding t o the discr etized continuit y equa tion is r e-sc aled using the c ell v olume and a sc ale fac tor, acc ording t o Equa- tion 11.32 (p.1364 ). coefficien t-based (default) sp ecifies tha t the diagonal en try of the linear ma trix sy stem c orresponding t o the discr etized c ontinuit y equa tion is dir ectly r e-sc aled b y a sc ale fac tor, acc ording t o Equa- tion 11.33 (p.1364 ). 47.10.12. Orientation C alcula tor D ialo g Box The Orientation C alcula tor dialo g box allo ws you t o convert rotation ma trices and E uler angles t o axis and angle f ormat. It also allo ws you t o concatenate rotations t o det ermine a r igid b ody’s final orientation. Figur e 47.2: Orientation C alcula tor D ialo g Box Controls Input Type allows you t o selec t which metho d you will use t o en ter your r igid b ody or ientation v alues . For additional information ab out these input t ypes, see Rigid B ody Motion (p.1349 ). Axis and A ngle allows you t o en ter the angle of r otation and the axis ab out which the r igid b ody is r otating . Rota tion M atrix allows you t o en ter the or ientation of the r igid b ody as a r otation ma trix. 3595Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dynamic M esh Task P ageEuler A ngles allows you t o en ter the or ientation of the r igid b ody as a set of E uler A ngles . For an e xplana tion of which Euler angles metho d Fluen t uses , see Rigid B ody Motion (p.1349 ). Output displa ys the angle of r otation and the axis ab out which the r igid b ody is r otating af ter you click Evalua te. Note tha t if y ou en ter a single or ientation in Axis and A ngle and click Evalua te, the v alues sho wn in Output will b e the same as y ou en tered in Axis and A ngle Conc atena te Next Input concatenates the ne xt input en tered (af ter click ing Evalua te) to the v alues displa yed in Output Evalua te converts the sp ecified input v alues in to angle and axis f ormat and displa ys the r esults in Output . Note that the c alculat or also c onverts the ent ered v alues int o the other t wo “grayed-out ” input f ormats . Fill enters the v alues displa yed in Output into the Rigid B ody Or ientation field of the Dynamic M esh Z ones dialo g box. 47.10.13. Infla tion S ettings D ialo g Box The Infla tion S ettings dialo g box allo ws you t o en ter infla tion la yer par amet ers f or a d ynamic z one . Controls Offset M etho d allows you t o selec t ho w the first la yer heigh t is e valua ted.The constan t type will use the same first heigh t for all elemen ts.The asp ect-ratio type will e valua te local first heigh ts such tha t the asp ect ratio (base siz e divided b y the elemen t heigh t) of the r esulting elemen ts is c onstan t. First A spect Ratio allows you t o sp ecify the asp ect ratio of the first elemen t if the Offset M etho d is set t o asp ect-ratio. First H eigh t allows you t o sp ecify the heigh t of the first elemen t if the Offset M etho d is set t o constan t. Growth R ate allows you t o sp ecify the geometr ic gr owth r ate of the infla tion elemen t heigh ts. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3596Task P age R eference GuideNumb er of L ayers allows you t o sp ecify the numb er of elemen ts in the infla tion la yer. Last A spect Ratio displa ys the asp ect ratio of the last elemen t for the giv en set of par amet ers if the Offset M etho d is set to asp ect-ratio. Total H eigh t displa ys the o verall thick ness of the infla tion la yer if the Offset M etho d is set t o constan t. 47.10.14. CutC ell B oundar y Zones Inf o Dialo g Box The CutC ell B oundar y Zones Inf o dialo g box displa ys a list of all of the b oundar y zones f or the C utCell dynamic c ell z one .This list also pr ovides the r emeshing par amet ers f or the z ones , including siz e func tion t ype, the maximum mesh siz e, the gr owth r ate used t o refine the mesh a t all of the C utCell boundar ies.The infla tion la yer settings used on all b oundar ies ar e also sho wn. 47.10.15. Zone Sc ale Inf o Dialo g Box The Zone Sc ale Inf o dialo g box allo ws you t o insp ect the v alues of minimum and maximum c ell ar ea or v olume , and maximum c ell sk ewness in a z one . Controls 3597Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dynamic M esh Task P ageMaximum L ength Sc ale displa ys the maximum c ell length in the z one . Minimum L ength Sc ale displa ys the minimum c ell length in the z one . Average L ength Sc ale displa ys the a verage c ell length in the z one . Maximum S kewness displa ys the maximum c ell sk ewness in the z one . 47.10.16. Zone M otion D ialo g Box The Zone M otion dialo g box will displa y the motion of z ones sp ecified with Rigid B ody or User- Defined motion. See Previewing the D ynamic M esh (p.1368 ) for details ab out the it ems b elow. Controls Time C ontrol contains c ontrols t o sp ecify the time in tervals a t which t o displa y the motion. Start Time (s) specifies the time fr om which t o star t the z one motion pr eview . Time S tep (s) specifies time st ep siz e for zone motion pr eview . Numb er of S teps specifies numb er of time st eps f or zone motion pr eview . Dynamic F ace Zones allows you t o selec t the d ynamic fac e zones t o pr eview . Only User-D efined or Rigid B ody zones ar e available . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3598Task P age R eference GuidePreview preview s the z one motion. Reset resets the z one displa y and the dialo g box inputs . 47.10.17. Mesh M otion D ialo g Box The Mesh M otion dialo g box allo ws you t o pr eview the d ynamic mesh as it changes with time b efore you star t your simula tion. See Previewing the D ynamic M esh (p.1368 ) for details . Controls Time contains the par amet ers t o sp ecify the time in terval at which t o up date the mesh. Current Mesh Time displa ys the cur rent time af ter the d ynamic mesh has b een ad vanced the sp ecified numb er of st eps. Time S tep S ize specifies the siz e of each time st ep. Numb er of Time S teps specifies the numb er of time st eps. Options contains options t o view the up dated mesh. Displa y M esh displa ys the mesh. Save Picture opens the Save Picture Dialog Box (p.3676 ), allo wing y ou t o sa ve a pic ture file of the mesh each time ANSY S Fluen t up dates it dur ing the mesh pr eview . 3599Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dynamic M esh Task P ageEnable A utosa ve opens the Autosave Case D uring M esh M otion P review D ialog Box (p.3600 ), allo wing y ou t o sa ve the case and da ta files with the sp ecified name and fr equenc y. See Automa tic S aving of C ase and D ata Files (p.591) for details . Update M esh In terfaces allows you t o up date the in terface at every time st ep. Update M onit ors allows you t o disable the pr ocessing of monit ors and c omputa tion ac tivities dur ing mesh motion preview . Displa y Frequenc y displa ys the fr equenc y at which ANSY S Fluen t will up date the mesh displa y. Preview allows you t o pr eview the motion of the selec ted z ones in the gr aphics windo w. 47.10.18. Autosa ve Case D uring M esh M otion P review D ialo g Box The Autosa ve Case D uring M esh M otion P review dialo g box allo ws you t o aut oma tically sa ve your case dur ing the d ynamic mesh pr eview as it changes with time , while r unning y our simula tion. See Automa tic S aving of C ase and D ata Files (p.591) for details ab out the inputs . Controls Save Case F ile E very contains the par amet ers t o sp ecify the time in terval at which t o up date the mesh. Retain Only the M ost Rec ent Files allows you t o restrict the numb er of files sa ved b y ANSY S Fluen t if y ou ha ve limit ed disk spac e.When this option is enabled , you c an en ter the appr opriate value in the Maximum N umb er of D ata F iles field . Note Only the asso ciated c ase files ar e retained when using this option. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3600Task P age R eference GuideMaximum N umb er of D ata F iles specifies the maximum numb er of da ta files tha t can b e sa ved a t an y instanc e. If you ha ve constr aints on the disk spac e, you c an r estrict the numb er of files t o be sa ved using this field . After sa ving the sp ecified numb er of files , ANSY S Fluen t will o verwrite the ear liest e xisting file .The default v alue f or this field is z ero, which sa ves all the files . Append F ile N ame with allows you t o selec t flow-time or time-st ep to be app ended t o the file name .This option is a vailable only f or unst eady-sta te calcula tions .The default selec tion is flow-time . 47.11. Ref erenc e Values Task P age The Referenc e Values task page allo ws you t o set the r eference quan tities used f or c omputing nor mal- ized flo w field v ariables . It also allo ws you t o sp ecify the r eference zone f or p ostpr ocessing r elative ve- locities in mo ving-z one pr oblems . See Reference Values (p.2952 ) for details ab out the it ems b elow. Controls Comput e from contains a dr op-do wn list of the b oundar y zones .You ma y selec t a z one t o be used f or aut oma tically de- fining the r eference values , but dep ending on the b oundar y condition used , all of the r eference values may not b e set. For e xample , the r eference length and ar ea will not b e set b y computing the r eference values fr om a b oundar y condition; you must set these manually . Referenc e Values contains inputs f or the r eference values . Area sets the r eference area, which is used t o comput e the f orce and momen t coefficien ts. Depth sets the r eference depth used f or computing c ell v olumes in 2D . 3601Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Reference Values Task P ageDensit y sets the r eference densit y, which is used t o comput e the r eference dynamic pr essur e. Enthalp y sets the r eference en thalp y, which is used t o det ermine the t otal en thalp y change . Length sets the r eference length, which is used in the c omputa tion of the momen t coefficien t. Pressur e sets the r eference pr essur e, which is used t o comput e the pr essur e-related f orces and momen ts and the pr essur e coefficien t. Temp erature sets the r eference temp erature, which is used t o comput e en tropy for inc ompr essible flo ws. Velocity sets the r eference velocity magnitude , which is used t o comput e the r eference dynamic pr essur e. Visc osit y sets the r eference kinema tic visc osity, which is used in the c omputa tion of the b oundar y Reynolds numb er. Ratio of S pecific H eats sets the v alue of the sp ecific hea t ratio, which is used in turb omachiner y efficienc y calcula tions . Referenc e Zone contains a dr op-do wn list of all c ell z ones in the domain. For flo ws involving multiple mo ving z ones , you must selec t the r eference zone f or p ostpr ocessing r elative velocities and r elated quan tities . See Setting the R eference Zone (p.2954 ) for details . 47.12. Solution Task P age The Solution task page in troduces y ou t o the main tasks in volved in solving y our CFD simula tion using ANSY S Fluen t. For mor e inf ormation ab out using ANSY S Fluen t to solv e your CFD simula tion, see Using the S olver (p.2559 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3602Task P age R eference Guide47.13. Solution M etho ds Task P age The Solution M etho ds task page allo ws you t o sp ecify v arious par amet ers asso ciated with the solution metho d to be used in the c alcula tion. Controls Formula tion provides a dr op-do wn list of the a vailable t ypes of solv er formula tions: Implicit and Explicit . This it em app ears only when the densit y-based solv er is used . Flux Type provides a dr op-do wn list of the c onvective flux t ypes:Roe-FDS ,AUSM , and Low D iffusion Ro e-FDS . Details ab out each of the flux t ypes c an b e found in Convective Fluxes in the Theor y Guide . Pressur e-Velocity Coupling contains settings f or pr essur e-velocity coupling schemes . Scheme (for the pr essur e-based solv er only) pr ovides a dr op-do wn list of the a vailable pr essur e-velocity coupling schemes: SIMPLE ,SIMPLEC ,PISO , and Coupled .When the non-it erative time ad vancemen t (NIT A) scheme is enabled in the Solution M etho ds task page ,Fractional S tep is a vailable f or single phase 3603Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Solution M etho ds Task P ageflows, and Phase C oupled SIMPLE is a vailable f or E uler ian multiphase flo ws. See Pressur e-Velocity Coupling in the Fluent Theor y Guide , and Choosing the P ressur e-Velocity Coupling M etho d (p.2570 ), Setting S olution C ontrols f or the N on-I terative Solver (p.2575 ), and Selec ting the P ressur e-Velocity Coupling M etho d (p.2264 ) for details ab out these metho ds. Skewness C orrection enables the SIMPLEC and PISO sk ewness c orrection f or highly sk ewed meshes if the v alue (numb er of iterations) is gr eater than 0. The default v alue is 0 f or SIMPLEC and 1 f or PISO . Neighb or C orrection enables the PISO neighb or correction, which is r ecommended f or tr ansien t calcula tions , if the v alue (numb er of it erations) is gr eater than 0. The default v alue is 1. Skewness-N eighb or C oupling allows for a mor e ec onomic al but a less r obust v ariation of the PISO algor ithm. Coupled with Volume F raction couples v elocity corrections , shar ed pr essur e corrections , and the c orrection f or v olume fr action sim- ultaneously .This option is a vailable in the in terface after you ha ve selec ted Coupled from the Scheme drop-do wn list f or Pressur e-Velocity Coupling . Solve N-P hase Volume F raction E qua tions solv es all pr imar y and sec ondar y volume fr action equa tions and sc ales the r esulting v olume fr actions to sa tisfy the r equir emen t tha t the y sum t o 1. If this is disabled , only the sec ondar y phase v olume fractions ar e solv ed dir ectly and the pr imar y phase v olume fr action is set such tha t the v olume fr actions sum t o 1. Spatial D iscr etiza tion contains settings tha t control the spa tial discr etiza tion of the c onvection t erms in the solution equa tions . See Choosing the S patial D iscretiza tion Scheme (p.2562 ) for details . Gradien t contains a dr op-do wn list of the options f or setting the metho d of c omputing the gr adien t in Equa- tion 28.33 in the Theor y Guide :Green-G auss C ell B ased ;Green-G auss N ode-B ased , and Least S quar es Cell B ased . See Evalua tion of G radien ts and D erivatives in the Theor y Guide for details . Pressur e (for the pr essur e-based solv er only) c ontains a dr op-do wn list of the discr etiza tion schemes a vailable for the pr essur e equa tion: Standar d,PREST O!,Linear ,Second Or der, and Body Force Weigh ted. This it em app ears only when the pr essur e-based solv er is used . Flow (for the densit y-based solv ers only) c ontains a dr op-do wn list of the discr etiza tion schemes a vailable for the pr essur e, momen tum, and (if r elevant) ener gy equa tions: First Or der U pwind ,Second Or der Upwind ,Third-Or der MUSCL , and (if the LES, DES, SAS, SDES, or SBES turbulenc e mo del is enabled) Bounded C entral D ifferencing . This it em app ears only when one of the densit y-based solv ers is used . Momen tum ,Energy, and so on are the names of the other c onvection-diffusion equa tions b eing solv ed. In the dr op-do wn list ne xt to each equa tion, you c an selec t the First Or der U pwind ,Second Or der U pwind ,QUICK , or Third-Or der MUSCL discr etiza tion scheme f or tha t equa tion. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3604Task P age R eference GuideIf the LES, DES, SAS, SDES, or SBES turbulenc e mo del is enabled , then y ou ha ve a choic e of se- lecting Bounded C entral D ifferencing or Central D ifferencing for Momen tum . If one of the densit y-based solv ers is used ,Momen tum and Energy will not app ear. For the densit y-based solv ers, the discr etiza tion scheme f or these equa tions is selec ted in the Flow drop-do wn list (descr ibed ab ove). Volume F raction is available when the VOF multiphase mo del is enabled .The discr etiza tion schemes tha t are used when solving v olume fr action equa tions f or the VOF e xplicit scheme ar e Geo-Rec onstr uct,Compr essiv e, CICSAM ,Modified HRIC , and QUICK .The discr etiza tion schemes tha t are used when solving v olume fraction equa tions f or the VOF implicit scheme ar e First Or der U pwind ,Second Or der U pwind , Compr essiv e,Modified HRIC ,BGM (steady sta te only), and QUICK . See Interpolation N ear the In terface in the Theor y Guide for detailed inf ormation ab out these VOF-sp ecific in terpolation schemes . Transien t Formula tion contains options f or setting diff erent time-dep enden t solution f ormula tions .This option app ears only when Transien t is enabled under Time in the Gener al task page . Available options include: Explicit (available only f or the Densit y Based Explicit solv er); First Or der Implicit ;Second Or der Implicit ; and Bounded S econd Or der Implicit . See Performing Time-D ependen t Calcula tions (p.2626 ) for details . Non-I terative Time A dvanc emen t enables non-it erative time-ad vancemen t (NIT A) scheme . See Time-A dvancemen t Algor ithm in the Theor y Guide for details . Acceler ated Time M arching enables a mo dified NIT A scheme and other setting changes tha t can sp eed up the simula tion. This option is only a vailable with the Lar ge E ddy Simula tion (LES) turbulenc e mo del, and is in tended f or unr eacting flow simula tions tha t use a c onstan t-densit y fluid . For details , see Setting S olution C ontrols f or the N on- Iterative Solver (p.2575 ). Frozen F lux F ormula tion enables an option t o discr etize the c onvective par t of Equa tion 28.68 in the Theor y Guide using the mass flux a t the c ell fac es fr om the pr evious time le vel n. This option is a vailable only f or a Transien t solution. See The F rozen F lux F ormula tion in the Theor y Guide for details . Pseudo Transien t enables an option t o apply the pseudo tr ansien t under-r elaxa tion metho d, which is a f orm of implicit under- relaxa tion (see Pseudo Transien t Under-R elaxa tion ).This option is a vailable f or the pr essur e-based solv er when Coupled is selec ted as the Pressur e-Velocity Coupling scheme and f or the densit y-based implicit solv er. Note tha t this metho d can only b e used when r unning a st eady-sta te simula tion. Warped-F ace Gradien t Correction enables an adjustmen t to the gr adien t discr etiza tion metho d tha t impr oves the gr adien t accur acy for meshes c ontaining high asp ect ratios, cells with non-fla t fac es, and highly def ormed c ells, and c an help avoid numer ical difficulties in simula tions tha t involve a mesh tha t has lar ge diff erences in the v olumes of neighb oring c ells. By default , the fast , or mor e computa tionally efficien t mo de of the w arped-fac e gr adien t correction is used . For additional inf ormation ab out the w arped-fac e gr adien t correction, see Warped-F ace Gradien t Correction (p.2697 ). Convergenc e Acceler ation F or S tretched M eshes Enable c onvergenc e acc eleration f or str etched meshes t o impr ove the c onvergenc e of the implicit densit y based solv er on meshes with high c ell str etching (see Convergenc e Acceleration f or S tretched M eshes (CASM) (p.2584 )). 3605Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Solution M etho ds Task P ageHigh Or der Term Relaxa tion enables the r elaxa tion of high or der t erms t o aid in the solution b ehavior of flo w simula tions when higher order spa tial discr etiza tion is used . Options ... Opens the Relaxa tion Options D ialog Box (p.3606 ). Set A ll Species D iscr etiza tions Together enables an option t o use the same discr etiza tion scheme f or all the sp ecies r ather than setting each of the species individually . Notice tha t you will no longer see y our list of individual sp ecies , inst ead a Species field will app ear with the scheme of y our choic e. Note tha t this option is a vailable when sp ecies tr ansp ort is enabled . Default sets the fields t o their default v alues , as assigned b y ANSY S Fluen t. Rep ort Poor Q ualit y Elemen ts reports sta tistics on the numb er and t ype of c ells tha t ANSY S Fluen t has iden tified as ha ving p oor qualit y. 47.13.1. Relaxa tion Options D ialo g Box The Relaxa tion Options dialo g box allo ws you t o fur ther c ontrol the High Or der Term Relaxa tion as descr ibed in High Or der Term R elaxa tion (HO TR) (p.2565 ). Controls Variables allows you t o selec t between under-r elaxing All Variables or only the default flo w variables ( Flow Vari- ables Only . Relaxa tion F actor is by default 0.25 f or st eady-sta te cases and 0.75 f or tr ansien t cases . 47.14. Solution C ontrols Task P age The Solution C ontrols task page allo ws you t o set c ommon solution par amet ers. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3606Task P age R eference GuideControls Cour ant Numb er sets the fine-gr id C ourant numb er (time st ep fac tor) when the densit y-based solv er is used . See Changing the C ourant Numb er (p.2581 ) for guidelines on setting the C ourant numb er. When the pr essur e-based solv er is used f or time-indep enden t flo ws, and the Coupled pressur e-ve- locity scheme is used , the Cour ant Numb er is used t o stabiliz e the c onvergenc e behavior. See Under- Relaxa tion of E qua tions in the Theor y Guide for a c orrelation of the under-r elaxa tion fac tor and courant numb er. Flow C our ant Numb er sets the C ourant numb er for multiphase flo w using the pr essur e-based c oupled solv er.The Flow C our ant Numb er is used t o stabiliz e the c onvergenc e behavior. Volume F raction C our ant Numb er sets the C ourant numb er for multiphase flo w using the pr essur e-based solv er is c oupled with the v olume fraction. The default v alue is 200 and will app ear in the in terface when the Coupled with Volume F raction option app ears in the Solution M etho ds task page . 3607Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Solution C ontrols Task P ageExplicit Relaxa tion F actors for the Coupled scheme defines the e xplicit r elaxa tion of v ariables b etween sub-it erations f or momen tum and pr essur e. See Under-R elaxa tion of Variables in the Theor y Guide for inf ormation. Multigr id L evels specifies the maximum numb er of c oarse le vels t o be created b y the F AS multigr id solv er.This it em is the same as the Max C oarse L evels under FAS M ultigr id C ontrols in the Multigr id tab of the Advanced Solution C ontrols D ialog Box (p.3611 ), and it app ears only when the densit y-based e xplicit solv er is used . Residual S moothing contains par amet ers tha t go vern the use of implicit r esidual smo othing . (See Implicit R esidual S moothing in the Theor y Guide and Using R esidual S moothing t o Incr ease the C ourant Numb er (p.2588 ) for details .) This sec tion of the task page will app ear only when the densit y-based e xplicit solv er is used . Iterations sets the numb er of it erations of the Jac obi smo other t o use . If Iterations is 0, then no implicit r esidual smo othing is p erformed . Smoothing F actor sets the implicit r esidual smo othing fac tor.This it em will not app ear unless Iterations is set t o a non- zero value . Under-Relaxa tion F actors contains the under-r elaxa tion fac tors f or all equa tions tha t are being solv ed with the pr essur e-based solv er. (See Setting U nder-R elaxa tion F actors (p.2573 ) for details .) In the field ne xt to each equa tion, you can set the under-r elaxa tion fac tor for tha t equa tion. When one of the densit y-based solv ers is used ,Under-Relaxa tion F actors will app ear only f or the following v ariables , when the y are included in y our mo del: solid (f or c onjuga te hea t transf er mo dels), turbulenc e variables , and visc osity.The solid under-r elaxa tion fac tor is used t o sc ale the CFL v alue in the solid r egion only if the under-r elaxa tion v alue is set t o a v alue less than 1. When the under- relaxa tion v alue is set t o 1, then the solv er ignor es the sp ecified CFL v alue f or the solid and inst ead uses a v ery lar ge v alue of CFL. This is done t o sp eed up the c onvergenc e in the solid r egion. The densit y-based solv ers use a segr egated metho d to solv e these equa tions; all the other equa tions are solv ed in a c oupled manner , so ther e ar e no under-r elaxa tion fac tors f or them. When Non-I terative Time A dvanc emen t is selec ted f or the pr essur e-based solv er, the Non-I terative Solver Relaxa tion F actors define the e xplicit r elaxa tion ( Under-R elaxa tion of Variables in the Theor y Guide ) of v ariables b etween sub-it erations and ar e used t o pr event the solution fr om div erging . When Pseudo Transien t is selec ted (a vailable with the pr essur e-based c oupled solv er), the Pseudo Transien t Explicit Relaxa tion F actors can b e sp ecified (see Setting P seudo Transien t Explicit R elax- ation F actors (p.2619 )). Acoustics Wave Equa tion S olver C ontrols contains par amet ers tha t go vern the ac oustics w ave equa tion solv er Rela tive Convergenc e Criterion sets the r elative convergenc e criterion f or the ac oustics w ave equa tion solv er. Max I tertation/T ime S tep sets the maximum numb er of it erations p er time st ep. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3608Task P age R eference GuideDefault sets the fields t o their default v alues , as assigned b y ANSY S Fluen t. Equa tions ... displa ys the Equa tions D ialog Box (p.3609 ). Limits ... displa ys the Solution Limits D ialog Box (p.3610 ). Advanc ed... displa ys the Advanced S olution C ontrols D ialog Box (p.3611 ). Set A ll Species URFs Together enables an option t o use the same under-r elaxa tion fac tors f or all the sp ecies r ather than setting each of the sp ecies individually . Notice tha t you will no longer see y our list of individual sp ecies , inst ead a Species field will app ear with the sp ecified under-r elaxa tion fac tor. Note tha t this option is a vailable when sp ecies transp ort is enabled . For additional inf ormation, see the f ollowing sec tions: 47.14.1. Equa tions D ialog Box 47.14.2. Solution Limits D ialog Box 47.14.3. Advanced S olution C ontrols D ialog Box 47.14.1. Equa tions D ialo g Box The Equa tions dialo g box contains a list of the equa tions b eing solv ed f or the cur rent mo del. To temp orarily disable solution of an equa tion, deselec t it in this list and click OK.To re-enable the c alcu- lation f or an equa tion, selec t it and click OK. See Step-b y-Step S olution P rocesses (p.2692 ) for details about using this f eature in a st ep-b y-step solution pr ocess. Note tha t, when one of the densit y-based solv ers is used ,Energy will not app ear as a separ ate item in the Equa tions list. For the densit y-based solv ers the ener gy equa tion is included in the Flow categor y (which also includes the pr essur e and momen tum equa tions). 3609Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Solution C ontrols Task P age47.14.2. Solution Limits D ialo g Box The Solution Limits dialo g box allo ws you t o impr ove the stabilit y of the solution. See Setting S olution Limits (p.2599 ) for details ab out the it ems b elow. Controls Minimum A bsolut e Pressur e, Maximum A bsolut e Pressur e set the limiting minimum and maximum allo wable v alues f or absolut e pr essur e. Minimum S tatic Temp erature, Maximum S tatic Temp erature set the limiting minimum and maximum allo wable v alues f or temp erature. Minimum Turb . Kinetic E nergy sets the limiting minimum v alue of turbulen t kinetic ener gy ( ) in the flo w field .This par amet er app ears when one of the - or - mo dels or the RSM is used . Minimum Turb . Dissipa tion R ate sets the limiting minimum v alue of turbulen t dissipa tion r ate ( ) in the flo w field .This par amet er app ears when one of the - mo dels or the RSM is used . Minimum S pec. Dissipa tion R ate sets the limiting minimum v alue of sp ecific dissipa tion r ate ( ) in the flo w field .This par amet er app ears when one of the - mo dels is used . Maximum Turb .Visc osit y Ratio sets the limiting maximum allo wable v alue of the r atio of turbulen t to laminar visc osity ( ).The tur- bulen t visc osity is r educ ed t o the nec essar y value so as not t o exceed the maximum allo wable visc osity ratio. This par amet er app ears f or all turbulen t flo ws. Minimum Vol. Frac. for M atrix S olution sets the limiting minimum v alue f or v olume fr action in the ma trix solution. This field app ears f or E uler ian multiphase simula tions r un on a double-pr ecision solv er. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3610Task P age R eference GuidePositivit y Rate Limit sets the limiting v alue f or the r ate of r educ tion of t emp erature. See Adjusting the P ositivit y Rate Limit (p.2601 ) for details . This it em app ears only when one of the densit y-based solv ers is used . Default sets the fields t o their default v alues , as assigned b y ANSY S Fluen t. After execution, the Default butt on becomes the Reset butt on. Reset resets the fields t o their most r ecently sa ved v alues (f or e xample , the v alues b efore Default was selec ted). After execution, the Reset butt on b ecomes the Default butt on. 47.14.3. Advanc ed S olution C ontrols D ialo g Box The Advanc ed S olution C ontrols dialo g box allo ws you t o set par amet ers r elated t o the multigr id, multi-stage , and non-it erative solv ers. 3611Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Solution C ontrols Task P ageControls Multigr id tab c ontains par amet ers r elated t o the multigr id solv er. See Modifying A lgebr aic M ultigr id Paramet- ers (p.2693 ) and Setting F AS M ultigr id Paramet ers (p.2596 ) for details ab out the it ems b elow. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3612Task P age R eference GuideCycle Type contains a dr op-do wn list f or each equa tion tha t is b eing solv ed. From this list y ou c an selec t the multigr id cycle t ype (Flexible ,V-C ycle,W-C ycle, or F-Cycle). See Specifying the M ultigr id C ycle Type (p.2591 ) for details . Note tha t, for the densit y-based solv ers, the Pressur e,Momen tum , and Energy equa tions will not app ear individually .They will inst ead b e gr oup ed t ogether and c alled Flow. Further mor e, for the densit y-based e xplicit solv er, the Cycle Type choic es for the Flow equa tions will b e limit ed t o V-C ycle and W-C ycle, while the choic es for Flow for the densit y-based implicit solv er will b e limit ed t o V-C ycle and F-Cycle. Termina tion specifies the t ermina tion cr iterion f or each equa tion tha t is b eing solv ed using algebr aic multigr id. See Setting the Termina tion and R esidual R educ tion P aramet ers (p.2591 ) for details . Restr iction specifies the r esidual r educ tion cr iterion f or each equa tion tha t is b eing solv ed using the Flexible algebr aic multigr id cycle. See Setting the Termina tion and R esidual R educ tion P aramet ers (p.2591 ) for details . (This it em will not app ear f or an equa tion tha t is using a V-C ycle,W-C ycle, or F-Cycle.) Stabiliza tion M etho d contains the dr op-do wn list t o cho ose the stabiliza tion metho d. For fur ther details , see Setting the Stabiliza tion M etho d (p.2591 ). BCGST AB enables the bi-c onjuga te gr adien t stabiliz ed metho d. RPM enables the r ecursiv e pr ojec tion metho d. RPM stabiliza tion is mainly used in c onjunc tion with the c oupled pr essur e-based solv er. CG enables the c onjuga te gr adien t metho d. CG stabiliza tion is mainly used in c onjunc tion with the segr egated pr essur e-based solv er. GMRES enables the gener alized minimal r esidual metho d. GMRES stabiliza tion is r ecommended f or cases that fail t o converge with the BC GSTAB metho d. Algebr aic M ultigr id C ontrols contains par amet ers r elated t o the algebr aic multigr id solv er. See Algebr aic M ultigr id (AMG) in the Theor y Guide and Modifying A lgebr aic M ultigr id Paramet ers (p.2693 ) for details . Scalar and C oupled P aramet ers contain par amet ers tha t you c an set , If you ar e using the densit y-based e xplicit solv er or the pressur e-based solv er with an y of the segr egated schemes , descr ibed in Pressur e-Velocity Coupling in the Theor y Guide and Choosing the P ressur e-Velocity Coupling M etho d (p.2570 ), you will only set Scalar P aramet ers. If you ar e using the densit y-based implicit or the pr essur e-based c oupled scheme , descr ibed in Coupled A lgor ithm , then y ou c an set the Coupled P aramet ers. 3613Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Solution C ontrols Task P ageFixed C ycle P aramet ers contains par amet ers tha t control the V,W, and F c ycles .You c an set the numb er of Pre-Sweeps and Post-S weeps , and the Max C ycles . Normally one p ost-sw eep is p erformed and no pr e- sweeps ar e done . See Fixed C ycle P aramet ers (p.2593 ) for details ab out using the it ems b elow. Pre-Sweeps sets the numb er of sw eeps t o perform b efore mo ving t o a c oarser le vel. Post-S weeps sets the numb er of sw eeps t o perform af ter coarser le vel corrections ha ve been applied . Max C ycles sets the maximum numb er of V,W, or F c ycles t o be performed .The multigr id solv er will continue t o solv e the set of equa tions un til either the maximum numb er of c ycles has been p erformed , or the Termina tion criteria ar e sa tisfied . Coarsening P aramet ers contains par amet ers tha t control the gr ouping of equa tions in the algebr aic multigr id al- gorithm. See Coarsening P aramet ers (p.2593 ) for details Max C oarse L evels is the maximum numb er of c oarse le vels tha t will b e built b y the multigr id solv er. Sets of coarser simultaneous equa tions ar e built un til the maximum numb er of le vels has b een created, or the c oarsest le vel has only 3 equa tions . Each le vel has ab out half as man y un- knowns as the pr evious le vel, so c oarsening un til ther e are only a f ew no des lef t will r equir e about as much t otal c oarse-le vel coefficien t storage as w as requir ed on the fine mesh. Reducing the maximum c oarse le vels will r educ e the memor y requir emen ts, but ma y re- quir e mor e iterations t o achie ve a c onverged solution. Setting Max C oarse L evels to 0 turns off the multigr id solv er. Coarsen b y controls the numb er of equa tions on each succ essiv ely c oarser gr id le vel. By default , this paramet er is set t o 2, indic ating tha t the numb er of equa tions on each le vel will b e 1/2 of the numb er on the pr evious le vel. In gener al, the numb er of equa tions on each c oarser grid le vel will b e appr oxima tely equal t o 1/ of the numb er on the pr evious le vel, wher e is the v alue set f or the Coarsen b y par amet er. Conser vative Coarsening enables the use of c onser vative coarsening t echniques tha t can impr ove par allel p erform- ance and/or c onvergenc e for some difficult c ases . Aggr essiv e Coarsening specifies the use of a v ersion of the AMG solv er tha t is optimiz ed f or high c oarsening r ates. It is r ecommended if the AMG solv er div erges with the default settings . Laplac e Coarsening enables the use of Laplac e coefficien ts when gr ouping c ells f or coarsening . Smoother Type consist of t wo types: Gauss-S eidel is the simplest smo other t ype and is r ecommended when using the pr essur e-based se- gregated solv er. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3614Task P age R eference GuideILU is mor e CPU in tensiv e, but has b etter smo othing pr operties f or blo ck-c oupled sy stems such as the pr essur e-based c oupled solv er and the densit y-based implicit solv er. Flexible C ycle P aramet ers contains par amet ers tha t control the fle xible multigr id cycle. Sweeps specifies the numb er of times t o apply the smo othing metho d each time a r elaxa tion is p er- formed . Max F ine Relaxa tions sets the maximum numb er of r elaxa tions t o be performed on the L evel 1 gr id (fine gr id le vel). This par amet er elimina tes the p ossibilit y tha t the G auss-S eidel solv er will get “stuck ” on the fine gr id le vel, unable t o reduc e the r esiduals b y the fr action ( ) requir ed b y the Termina tion criteria. Max C oarse Relaxa tions sets the maximum numb er of r elaxa tions t o be performed on each gr id le vel ab ove Level 1 (tha t is, the c oarse gr id le vels). This par amet er elimina tes the p ossibilit y tha t the G auss-S eidel solv er will get “stuck ” on a c oarse gr id le vel, unable t o reduc e the r esiduals on tha t level by the fr action ( ) requir ed b y the Termina tion criteria. If the it erative solution on a giv en gr id level is unable t o meet the accur acy constr aint of the Termina tion criteria, the c orrection equa tion will b e deemed “converged ” when this maximum numb er of r elaxa tions on tha t grid le vel has b een p erformed . Options contains additional multigr id par amet ers. Verb osit y controls the amoun t of inf ormation tha t is pr inted out b y the multigr id solv er for monit oring purposes . See Setting the Verbosity (p.2595 ) for details FAS M ultigr id C ontrols contains par amet ers r elated t o the F AS multigr id solv er. See Full-A pproxima tion S torage (F AS) M ultigr id in the Theor y Guide and Setting F AS M ultigr id Paramet ers (p.2596 ) for details . As not ed in the title of this dialo g box sec tion, the F AS multigr id solv er is used only f or the Flow equa tions (pr essur e, mo- men tum, and ener gy). This sec tion of the dialo g box app ears only when the densit y-based e xplicit solv er is used . Fixed C ycle P aramet ers contains par amet ers tha t control the V,W, and F c ycles of the F AS multigr id solv er. Pre-Sweeps sets the numb er of it erations of the multi-stage solv er to be performed on a giv en gr id le vel before pr oceeding t o a c oarser gr id le vel (the v alue of descr ibed in Multigr id C ycles in the Theor y Guide ).Typic ally, this is set t o 1. Post-S weeps sets the numb er of multigr id cycles t o be performed on a giv en gr id le vel before pr oceeding back up t o the finer gr id le vel (the v alue of descr ibed in Multigr id C ycles in the Theor y Guide ). A value of 1 r esults in V-cycle multigr id, and a v alue of 2 r esults in W-c ycle multigr id. 3615Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Solution C ontrols Task P ageCoarsening P aramet ers contains par amet ers tha t control the gr ouping of c ells in the F AS multigr id algor ithm. Max C oarse L evels sets the maximum numb er of gr id le vels t o be used in the multigr id pr ocess. A value of 0 disables multigr id (no c oarse gr id le vels). If the c oarse gr ids do not alr eady exist, the y are created aut oma tically when y ou star t iterating; you c annot cr eate them b y click ing the OK butt on. See Turning On F AS M ultigr id (p.2587 ) for details . Coarsen b y controls the numb er of c ells in each succ essiv ely c oarser gr id le vel. By default , this par amet er is set t o 2, indic ating tha t the numb er of c ells on each le vel will b e 1/2 of the numb er on the previous le vel. In gener al, the numb er of c ells on each c oarser gr id le vel will b e equal t o 1/ of the numb er on the pr evious le vel, wher e is the v alue set f or the Coarsen b y par amet er. Relaxa tion F actors are pr ovided t o mo derate and stabiliz e the multigr id corrections . Cour ant Numb er Reduc tion sets the fac tor b y which t o reduc e the C ourant numb er for coarse gr id le vels (tha t is, every level except the finest). Some r educ tion of time st ep (such as the default 0.9) is t ypic ally r e- quir ed b ecause the stabilit y limit c annot b e det ermined as pr ecisely on the ir regular ly shap ed coarser gr id cells. Correction Reduc tion sets the fac tor b y which t o reduc e the magnitude of the multigr id corrections tr ansf erred from one le vel to the ne xt finer le vel. A typic al value with is 0.6. If two Pre-Sweeps and two Post-S weeps are performed , this v alue c an of ten b e incr eased t o 1.0 (tha t is, full c orrection transf er). Species C orrection Reduc tion sets the fac tor b y which t o reduc e the magnitude of the sp ecies c orrections t o stabiliz e the multigr id calcula tion. This it em app ears only when sp ecies tr ansp ort is b eing mo deled . Correction S moothing sets the c orrection smo othing fac tor used t o interpolate corrections fr om a c oarser gr id to a finer gr id. For multigr id on str uctured meshes , corrections c an b e interpolated up t o a finer mesh “smo othly ” by using , for e xample , tri-linear in terpolation. For unstr uctured meshes ther e is no analo gous simple , algebr aic pr ocedur e tha t can b e used t o interpolate without in troducing substan tial high fr equenc y “noise ”. Inst ead, the c orrections ar e first in terpolated, and then subjec ted t o a smo othing pass .The default Correction S moothing value of 0.5 should b e acceptable f or all c ases; you should not need t o change it. Options contains additional multigr id par amet ers. Verb osit y controls the amoun t of inf ormation tha t is pr inted out b y the multigr id solv er for monit oring purposes . Multi-S tage tab allo ws you t o set par amet ers tha t go vern the op eration of the multi-stage solv er. It is a vailable only when the densit y-based e xplicit solv er is used . See Changing the M ulti-S tage Scheme (p.2602 ) for details ab out the it ems b elow. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3616Task P age R eference GuideControls Numb er of S tages is the numb er of stages used in the multi-stage scheme .The default scheme is a 3-stage scheme with c oefficien ts of 0.2075, 0.5915, and 1.0 f or the first thr ough thir d stages , respectively. Although the dialo g box limits the maximum numb er of stages t o fiv e, you c an define a scheme with an arbitr ary numb er of stages with the solve/set/multi-stage text command . Stage labels the stage t o which the par amet ers in the other c olumns apply . Coefficien t sets the multi-stage c oefficien t for each stage . Coefficien ts should b e gr eater than z ero and less than one .The final stage should alw ays ha ve a c oefficien t of 1. Dissipa tion sets the stages f or which ar tificial dissipa tion is e valua ted. If a Dissipa tion box is selec ted f or a particular stage , artificial dissipa tion will b e up dated on tha t stage . If not selec ted, artificial dissip- ation will r emain “frozen” at the v alue of the pr evious stage . Visc ous sets the stages f or which visc ous str esses ar e evalua ted. If a Visc ous box is selec ted f or a par ticular stage , visc ous str esses will b e up dated on tha t stage . If not selec ted, visc ous str esses will r emain “frozen” at the v alue of the pr evious stage .Viscous str esses should alw ays be comput ed on the first stage , and succ essiv e evalua tions will incr ease the “robustness ” of the solution pr ocess, but will also incr ease the e xpense (tha t is, incr ease the CPU time p er it eration). For st eady pr oblems , the final solution is indep enden t of the stages on which visc ous str esses ar e up dated. Default sets the fields t o their default v alues , as assigned b y ANSY S Fluen t. After execution, the Default butt on b ecomes the Reset butt on. 3617Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Solution C ontrols Task P ageReset resets the fields t o their most r ecently sa ved v alues (tha t is, the v alues b efore Default was selec ted). After execution, the Reset butt on b ecomes the Default butt on. Expert tab c ontains sp ecializ ed par amet ers f or limiting spa tial discr etiza tion, as w ell as c ontrols f or the non- iterative solv er. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3618Task P age R eference GuideControls Spatial D iscr etiza tion Limit er contains c ontrols f or limiting the spa tial discr etiza tion. See Selec ting G radien t Limit ers (p.2603 ) for mor e inf ormation ab out limit ers. Limit er Type selec ts the t ype of limit er applied t o the spa tial discr etiza tion: Standar d,Multidimensional , or Differentiable . Cell t o Face Limiting is wher e the limit ed v alue of the r econstr uction gr adien t is det ermined a t the c ell fac e centers. This is the default metho d. Cell t o Cell Limiting is wher e the limit ed v alue of the r econstr uction gr adien t is det ermined along a sc aled line between t wo adjac ent cell c entroids . On an or thogonal mesh (or when the c ell-t o-cell dir ection is par allel t o fac e area dir ection), this metho d becomes equiv alen t to the default c ell to fac e metho d. For smo oth field v ariation, cell to cell limiting ma y pr ovide less numer ical dissipa tion on meshes with sk ewed c ells. Apply Limit er F ilter enables the limit er filt er.The limit er filt er is only a vailable with the Standar d and Differentiable limit er types. Pseudo Transien t Metho d Usage allows you t o selec t and mo dify the par amet ers f or each individual equa tion. See Setting S olution Controls f or the P seudo Transien t Metho d (p.2621 ) for details . On/O ff enables/disables the equa tion-sp ecific st eady sta te solution metho d for a par ticular equa tion. Under-Relaxa tion F actor allows you t o use the standar d steady sta te metho d by tur ning off pseudo tr ansien t for tha t particular equa tion. Specify the c orresponding under-r elaxa tion fac tor to be emplo yed with a par ticular equa tion. Time Sc ale F actor allows you t o sp ecify a fac tor tha t scales the pseudo time st ep emplo yed f or the flo w equa tions specified in the Run C alcula tion task page . A time sc ale fac tor other than 1.0 (default) allo ws the use of an equa tion sp ecific time st ep in lieu of using a unif orm global pseudo time st ep. Non-I terative Solver C ontrols contain par amet ers tha t control the sub-it erations f or the individual equa tions . See Time-A dvance- men t Algor ithm in the Theor y Guide for details . Max. Corrections provide c ontrol over the maximum numb er of sub-it erations f or each individual equa tion. Correction Toler anc e defines the o verall accur acy. Residual Toler anc e controls the solution of the linear equa tions . 3619Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Solution C ontrols Task P ageDefault sets the fields t o their default v alues , as assigned b y ANSY S Fluen t. After execution, the Default butt on becomes the Reset butt on. Reset resets the fields t o their most r ecently sa ved v alues (tha t is, the v alues b efore Default was selec ted). After execution, the Reset butt on b ecomes the Default butt on. 47.15. Solution Initializa tion Task P age The Solution Initializa tion task page allo ws you t o define v alues f or flo w variables and initializ e the flow field t o these v alues . See f or details ab out using this dialo g box. Controls Initializa tion M etho d allows you t o cho ose b etween Hybr id Initializa tion and Standar d Initializa tion . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3620Task P age R eference GuideHybr id Initializa tion is a c ollec tion of b oundar y interpolation metho ds, wher e variables , such as t emp erature, turbulenc e, species fr actions , volume fr actions , and so on, are aut oma tically pa tched based on domain a veraged values or a par ticular in terpolation r ecip e (see Hybrid Initializa tion (p.2611 )). Standar d Initializa tion allows you t o define v alues f or flo w variables and initializ e the flo w field t o these v alues . Comput e from is a dr op-do wn list of z ones; the default v alues f or applic able v ariables will b e comput ed fr om inf ormation contained in the z one tha t you selec t from this list. The c omputa tion will o ccur when y ou selec t the r equir ed zone , and the v ariable v alues will b e displa yed in Initial Values .You c an also cho ose the all-z ones item in this list t o comput e average v alues based on all z ones . Referenc e Frame indic ates whether the initial v elocities ar e absolut e velocities ( Absolut e) or v elocities r elative to the motion of each c ell z one ( Rela tive to Cell Z one ).This selec tion is nec essar y only if y our pr oblem in volves mo ving reference frames or sliding meshes . If ther e is no z one motion, both options ar e equiv alen t. Initial Values displa ys the initial v alues of applic able v ariables .You c an use Comput e from to comput e values fr om a particular z one , or y ou c an en ter values dir ectly. For sp ecies tr ansp ort cases with a single phase flo w, only the b oundar y sp ecies tha t you ha ve selec ted in the Selec t Boundar y Species dialo g box (see Figur e 15.3: The Selec t Boundar y Species D ialog Box (p.1623 )) app ear in the list. You c an add or r emo ve a sp ecies using the Selec t Boundar y Species dialo g box tha t can b e acc essed b y click ing Species in the Initializa tion task page . Initializ e initializ es the en tire flo w field t o the v alues list ed. Initializ e Acoustics ... opens the Acoustics Initializa tion D ialog Box (p.3622 ). Reset resets the fields t o their “saved” values . Patch... opens the Patch D ialog Box (p.3622 ). Species opens the Selec t Boundar y Species dialo g box (see Figur e 15.3: The S elec t Boundar y Species D ialog Box (p.1623 )), wher e you c an selec t the b oundar y sp ecies t o be displa yed in the Initial Values list and in the Patch,Hybr id Initializa tion , and r elevant boundar y conditions dialo g boxes.You c an mo dify the se- lected b oundar y sp ecies list on the fly dur ing the pr oblem setup .This it em app ears f or sp ecies tr ansp ort cases with a single phase flo w only . Reset DPM S our ces allows you t o reset the in terphase sour ces/sinks of momen tum, hea t, and/or mass t o zero.This it em is available when y ou p erform coupled discr ete phase c alcula tions . See Resetting the In terphase Ex change Terms (p.2027 ) for details . Reset S tatistics can b e used t o both initializ e the flo w sta tistics and r eset the flo w sta tistics af ter you ha ve ga ther ed some data for time sta tistics .This it em is a vailable when y ou p erform unst eady calcula tions and ha ve enabled 3621Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Solution Initializa tion Task P agethe Data S ampling f or Time S tatistics option in the Run C alcula tion Task P age (p.3640 ). See User Inputs for Time-D ependen t Problems (p.2627 ) for details . VOF C heck prints a summar y report for the VOF c ase setup .This butt on is displa yed only f or VOF multiphase c ases . It becomes a vailable af ter the c ase is initializ ed. For details , see Multiphase C ase C heck (p.2278 ). More Settings ... opens the Hybrid Initializa tion D ialog Box (p.3624 ).This butt on is a vailable only when Hybr id Initializa tion is the selec ted metho d. For additional inf ormation, see the f ollowing sec tions: 47.15.1. Acoustics Initializa tion D ialog Box 47.15.2. Patch D ialog Box 47.15.3. Hybrid Initializa tion D ialog Box 47.15.1. Acoustics Initializa tion D ialo g Box The ac oustics initializa tion dialo g box allo ws you t o initializ e/reinitializ e the solution of the ac oustics wave equa tion and t o sp ecify ho w long t o ramp ac oustic sour ces. Figur e 47.3: The A coustics Initializa tion D ialo g Box Controls Numb er of Timest eps f or R amping of S our ces sets ho w man y timest eps the sound sour ces will r amp t o their full v alues . 47.15.2. Patch D ialo g Box The Patch dialo g box allo ws you t o pa tch diff erent values of flo w variables in to diff erent cells. See Patching Values in S elec ted C ells (p.2607 ) for details ab out using this f eature. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3622Task P age R eference GuideControls Referenc e Frame indic ates whether pa tched v elocities ar e absolut e velocities ( Absolut e) or v elocities r elative to the motion of each c ell z one ( Rela tive to Cell Z one ).This selec tion is nec essar y only if y our pr oblem in volves mo ving reference frames or sliding meshes . If ther e is no z one motion, both options ar e equiv alen t. Also, this se- lection aff ects only v elocities , so the options will not b e available unless y ou ha ve selec ted a v elocity in the Variable list. Phase contains a list of all of the phases in the pr oblem tha t you ha ve defined .This is a vailable when the VOF, mixture, or E uler ian multiphase mo del is enabled . Variable contains a list of flo w variables fr om which y ou c an cho ose the v ariable t o be pa tched . For sp ecies tr ansp ort cases with a single phase flo w, only the b oundar y sp ecies tha t you ha ve selec ted in the Selec t Boundar y Species dialo g box (see Figur e 15.3: The S elec t Boundar y Species D ialog Box (p.1623 )) app ear in the list. You c an add or r emo ve a sp ecies using the Selec t Boundar y Species dialo g box tha t can b e acc essed by click ing Species in the Initializa tion task page . Volume F raction P atch Options contains options tha t can b e used when pa tching v olume fr action f or VOF and E uler ian multiphase with Multi-F luid VOF simula tions . Patch Rec onstr ucted In terface applies a piec ewise-linear r econstr uction of the in terface when pa tching a user-defined r egist er and patches c ells tha t intersec t the in terface with the ac tual v olume fr action. Volumetr ic Smoothing enables smo othing of the v olume fr action based on the v olumetr ic average o ver the c ell neighb ors. After enabling v olumetr ic smo othing , you c an click S mooth t o apply smo othing t o the v olume fr action field f or all phases in the en tire domain. Smoothing Relaxa tion F actor controls the degr ee of smo othing applied t o the v olume fr action field .This c an b e set b etween 0 (no smo othing) and 1 (maximum smo othing). 3623Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Solution Initializa tion Task P ageValue sets a c onstan t value t o be pa tched f or the selec ted Variable . Use F ield F unc tion enables the pa tching of a cust om Field F unc tion , rather than a c onstan t Value , for the selec ted Variable . See Using F ield F unctions (p.2609 ) for details . Field F unc tion contains a list of defined cust om field func tions . If the Use F ield F unc tion option is enabled , you c an patch one of these func tions f or the selec ted Variable . See Using F ield F unctions (p.2609 ) for details . Zones t o Patch contains a list of c ell z ones .The sp ecified Value or Field F unc tion for the selec ted Variable will b e patched in to the z ones y ou selec t from this list. Regist ers t o Patch contains a list of c ell regist ers tha t ha ve been cr eated using the adaption t ools.You c an pa tch a diff erent value f or a gr oup of c ells within a single c ell z one b y selec ting a r egist er containing a subset of the c ells in the z one . See Using R egist ers (p.2609 ) for details . Patch updates the flo w-field da ta based on the inputs ab ove. Smooth apply v olumetr ic smo othing t o the v olume fr action field .This butt on only app ears if Volumetr ic Smoothing is enabled . 47.15.3. Hybrid Initializa tion D ialo g Box The Hybr id Initializa tion dialo g box contains a host of adjustable settings tha t control the Hybr id Initializa tion strategy. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3624Task P age R eference GuideControls Gener al S ettings allow you t o adjust such en tries as the numb er of it erations and under-r elaxa tion fac tors. Numb er of I terations uses a default v alue of 10. This is the numb er of it erations tha t will b e performed while solving the Laplac e equa tions t o initializ e the v elocity and pr essur e. If the initializ ed v elocity and pr essur e fields are not t o your lik ing, you ma y want to incr ease the numb er of it erations and r e-initializ e the solution. Explicit U nder-Relaxa tion F actor uses a default v alue of 1. This v alue will b e used while solving the Laplac e equa tion t o initializ e the velocity and pr essur e. If the initializ ed v elocity and pr essur e fields ar e not t o your lik ing, you ma y want to adjust the under-r elaxa tion fac tor and r e-initializ e the solution. Referenc e Frame indic ates whether the initial v elocities ar e absolut e velocities ( Absolut e) or v elocities r elative to the motion of each c ell z one ( Rela tive to Cell Z one ).This selec tion is nec essar y only if y our pr oblem in- volves mo ving r eference frames or sliding meshes . If ther e is no z one motion, both options ar e equi- valen t. Initializa tion Options allows you t o include an y of the thr ee initializa tion options . 3625Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Solution Initializa tion Task P ageUse S pecified Initial P ressur e on Inlets if you w ant the sp ecified pr essur e for Supersonic/Initializa tion G auge P ressur e at the inlet boundar ies t o be used f or solving the Laplac e equa tion f or the pr essur e. Use E xternal-A ero Favorable S ettings if you w ant to ha ve the v elocity potential pa tched with a linear v alue t o help acc elerate conver- genc e of Scalar E qua tion–0 and t o obtain a b etter guess of the v elocity field f or e xternal-aer o problems . Maintain C onstan t Velocity M agnitude if you w ant to use the flo w dir ection obtained fr om solving the v elocity potential ( Scalar E qua- tion–0 ), while main taining a c onstan t velocity magnitude thr oughout the c omputa tional domain. Turbulenc e Settings uses b y default the domain a veraged v alues f or the turbulenc e par amet ers. If you w ant to use v ariable turbulenc e par amet ers y ou c an deselec t the Average Turbulen t Paramet ers check b ox.When this option is disabled , then it c alcula tes the turbulen t par amet ers, such as k inetic ener gy, dissipa tion ener gy, and so on, using lo cal flo w par amet ers. Species S ettings will b y default initializ e sec ondar y sp ecies with z ero mass or mole fr actions . If you w ant to sp ecify the appr opriate value f or the sp ecies , you must enable Specify S pecies P aramet ers. Note tha t only the boundar y sp ecies tha t you ha ve selec ted in he Selec t Boundar y Species dialo g box (see Figur e 15.3: The Selec t Boundar y Species D ialog Box (p.1623 )) app ear in the list. You c an add or r emo ve a sp ecies using the Selec t Boundar y Species dialo g box tha t can b e acc essed b y click ing Species in the Initializa tion task page . 47.16. Calcula tion A ctivities Task P age The Calcula tion A ctivities task page allo ws you t o set up v arious tasks tha t you c an p erform dur ing the c alcula tion, such as sa ving files , exporting files , creating solution anima tions , and c ommand e xecution. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3626Task P age R eference GuideControls Autosa ve Every allows you t o set the fr equenc y of the aut osave. Edit... opens the Autosave Dialog Box (p.3628 ). Automa tic E xport displa ys a list of a vailable e xport objec ts tha t will b e execut ed dur ing the c alcula tions .This list and its as- sociated butt ons ar e only a vailable f or tr ansien t flo w calcula tions . 3627Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Calcula tion A ctivities Task P ageCreate provides a dr op-do wn list tha t contains options f or cr eating e xport objec ts.Two options ar e available: the Solution D ata E xport option op ens the Automa tic Exp ort Dialog Box (p.3631 ); the Particle Hist ory Data E xport option op ens the Automa tic P article Hist ory Data Exp ort Dialog Box (p.3635 ). Edit... opens the appr opriate dialo g box for the selec ted it em in the Automa tic E xport list. Delet e remo ves the selec ted it em fr om the Automa tic E xport list. Execut e Commands lists a vailable c ommands t o be execut ed dur ing the c alcula tions . Create/Edit... opens the Execut e Commands D ialog Box (p.3637 ). Automa tically Initializ e Solution and M odify C ase allows you t o aut oma tically ha ve your solution initializ ed and y our c ase file mo dified . Edit... opens the Automa tic S olution Initializa tion and C ase M odific ation D ialog Box (p.3638 ).This butt on is only a vailable when the Automa tically Initializ e Solution and M odify C ase option is enabled . For additional inf ormation, see the f ollowing sec tions: 47.16.1. Autosave Dialog Box 47.16.2. Data File Q uantities D ialog Box 47.16.3. Automa tic Exp ort Dialog Box 47.16.4. Automa tic P article Hist ory Data Exp ort Dialog Box 47.16.5. Execut e Commands D ialog Box 47.16.6. Define M acro Dialog Box 47.16.7. Automa tic S olution Initializa tion and C ase M odific ation D ialog Box 47.16.1. Autosa ve Dialo g Box The Autosa ve dialo g box allo ws you t o sp ecify aut oma tic sa ving of c ase and da ta files a t sp ecified intervals dur ing a c alcula tion. See Automa tic S aving of C ase and D ata Files (p.591) for details . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3628Task P age R eference GuideControls Save Data F ile E very specifies the fr equenc y with which da ta files ar e sa ved. For st eady flo ws you will sp ecify the fr equenc y in it erations , while f or unst eady flo ws you will sp ecify it in either time st eps or flo w time (unless y ou ar e using the e xplicit time st epping f ormula tion, in which c ase y ou will sp ecify the fr equenc y in it erations or if you ar e running an in-c ylinder simula tion y ou c an sp ecify the fr equenc y in cr ank angles). The default value is set t o zero, indic ating tha t no aut oma tic sa ving is p erformed . Save Associated C ase F iles gives y ou the choic e to sa ve the c ase file only if it is mo dified or each time tha t the da ta file is sa ved. Only if M odified results in ANSY S Fluen t saving a c ase file only if ther e is a change in the c ase file settings . Each Time allows you t o sa ve the c ase file e very time the da ta file is sa ved. Retain Only the M ost Rec ent Files allows you t o restrict the numb er of files sa ved b y ANSY S Fluen t if y ou ha ve limit ed disk spac e.When this option is enabled , you c an en ter the appr opriate value in the Maximum N umb er of D ata F iles field . Only the asso ciat ed c ase files ar e retained when using this option. Imp ortant When the Retain Only the M ost Rec ent Files option is selec ted, the solution hist ory currently in memor y will b e disc arded and the solution hist ory reset. 3629Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Calcula tion A ctivities Task P ageData F ile Q uan tities opens the Data File Q uan tities D ialog Box (p.3630 ) wher e you c an sp ecify which quan tities y ou w ant to automa tically sa ve to a da ta file f or p ostpr ocessing . Maximum N umb er of D ata F iles specifies the maximum numb er of da ta files tha t can b e sa ved a t an y instanc e. If you ha ve constr aints on the disk spac e, you c an r estrict the numb er of files t o be sa ved using this field . After sa ving the sp ecified numb er of files , ANSY S Fluen t will o verwrite the ear liest e xisting file .The default v alue f or this field is z ero, which sa ves all the files . File N ame specifies the r oot name f or the files tha t are sa ved.The it eration or time-st ep numb er and an appr opriate suffix (.cas or .dat ) will b e added t o the sp ecified r oot name . If the sp ecified File N ame ends in .gz or .Z, appr opriate file c ompr ession will b e performed . (See Reading and Writing C ompr essed F iles (p.583) for details ab out file c ompr ession.) Append F ile N ame with allows you t o selec t flow-time ,time-st ep, or crank-angle to be app ended t o the file name .This option is available only f or unst eady-sta te calcula tions (only f or in-c ylinder c alcula tions in the c ase of crank- angle ).The default selec tion is flow-time . Decimal P laces in F ile N ame allows you t o sp ecify the numb er of decimal digits in the file name .This option is a vailable only when flow-time or crank-angle is selec ted in the Append F ile N ame with drop-do wn list. The default v alue for this field is set t o 6. 47.16.2. Data F ile Q uan tities D ialo g Box The Data F ile Q uan tities dialo g box allo ws you t o sp ecify v arious quan tities f or p ostpr ocessing . See Setting D ata File Q uan tities (p.651) for details . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3630Task P age R eference GuideControls Standar d Q uan tities contains a listing of standar d postpr ocessing quan tities (f or e xample , densit y, Mach numb er, temp erature, and so on). Additional Q uan tities contains a listing of additional p ostpr ocessing quan tities tha t are der ived fr om the standar d quan tities (for e xample , standar d pr essur e, velocity magnitude , and so on). 47.16.3. Automa tic E xport Dialo g Box The Automa tic E xport dialo g box allo ws you t o cr eate an aut oma tic e xport definition f or solution data. See Creating A utoma tic Exp ort Definitions f or S olution D ata (p.629) for details . 3631Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Calcula tion A ctivities Task P ageControls Name specifies the name of the e xport definition. File Type contains a dr op-do wn list of file t ypes, which c ontrol the output file f ormat tha t will b e wr itten. ABAQUS allows you t o sp ecify the sur face(s) and optional loads , based on the k ind of finit e elemen t analy sis selec ted, to be exported t o an AB AQUS file (e xtension .inp ). ASCII allows you t o sp ecify the sur face(s), scalars , location fr om which the v alues of sc alar func tions ar e to be tak en, and the delimit er separ ating the fields , to be exported t o an ASCII file . AVS allows you t o sp ecify the sc alars y ou w ant to wr ite to be exported t o an A VS file . CDA T for CFD-P ost & E nSight allows you t o sp ecify the c ell z ones , surfaces, quan tities , format (Binar y or ASCII ), and whether a c ase file is wr itten for da ta export.The .cdat file f ormat is c ompa tible with b oth CFD-P ost and EnS ight. CGNS allows you t o sp ecify the sc alars y ou w ant to wr ite and the lo cation fr om which the v alues of sc alar func tions ar e to be tak en, to be exported t o a C GNS file (e xtension .cgns ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3632Task P age R eference GuideData E xplor er allows you t o sp ecify the sur face(s) and the sc alars y ou w ant to wr ite to be exported t o a D ata Ex- plor er file (e xtension .dx ). EnSight Case G old allows you t o sp ecify the sc alars y ou w ant to wr ite, the c ell z ones , interior z one sur faces, and lo cation in the c ell fr om which the v alues of sc alar func tions ar e to be tak en, and the file f ormat, to be exported to an EnS ight file (e xtension .geo ,.vel ,.scl1 , or .encas ). FAST allows you t o sp ecify the sc alars y ou w ant to wr ite, to be exported as a gr id file (P lot3D f ormat), a velocity file , and a sc alar file .This option is a vailable only f or a tr iangular or t etrahedr al mesh. FAST S olution allows you t o export a single file c ontaining densit y, velocity, and t otal ener gy da ta.This option is available only f or a tr iangular or t etrahedr al mesh. Field view U nstr uctured allows you t o sp ecify the sc alars y ou w ant to wr ite and the c ell z ones fr om which the v alues of sc alar func tions ar e to be tak en, to be exported t o a FIELD VIEW binar y file (e xtension .fvuns ) and a r egions file (e xtension .fvuns.fvreg ). I-deas U niversal allows you t o sp ecify the sur face(s), scalars , and optional loads , based on the k ind of finit e elemen t analy sis selec ted, to be exported t o an I-deas U niversal file . Mechanic al APDL Input allows you t o sp ecify the sur face(s) and optional loads , based on the k ind of finit e elemen t analy sis selec ted, to be exported t o a M echanic al APDL Input file (e xtension .cdb ). NASTR AN allows you t o sp ecify the sur face(s), scalars , and optional loads , based on the k ind of finit e elemen t analy sis selec ted, to be exported t o a NASTR AN file (e xtension .bdf ). PATRAN allows you t o sp ecify the sur face(s), scalars , and optional loads , based on the k ind of finit e elemen t analy sis selec ted, to be exported t o a P ATRAN neutr al file (e xtension .out ). TAITherm allows you t o sp ecify the sur face(s) f or which y ou w ant to wr ite da ta and the metho d of wr iting the heat transf er coefficien t, to be exported t o a P ATRAN neutr al file (e xtension .neu ).This option is available only when the Energy Equa tion is enabled . Tecplot allows you t o sp ecify the sur face(s) and the sc alars y ou w ant to wr ite, to be exported t o a Tecplot file . Cell Z ones specifies the c ell z ones f or which da ta is t o be wr itten for a CFD-P ost c ompa tible , EnS ight, or FIELD VIEW file . Surfaces specifies the sur faces for which da ta is t o be wr itten for an AB AQUS, ASCII, Data Explor er, I-deas U niversal, Mechanic al APDL Input , NASTR AN, PATRAN, TAITherm, or Tecplot file . 3633Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Calcula tion A ctivities Task P ageQuan tities specifies v alid quan tities f or output. The a ttribut es of the list ar e mo dified based on the ac tive file t ype. The list ma y be a single-selec tion or a multiple-selec tion list or it ma y be disabled , dep ending on the se- lected File Type. Analy sis (for ABAQUS ,I-deas U niversal ,Mechanic al APDL Input ,NASTR AN, and PATRAN formats) specifies the finit e elemen t analy sis in tended . Structural specifies str uctural analy sis and allo ws you t o selec t the Structural L oads to be wr itten. Thermal specifies ther mal analy sis and allo ws you t o selec t the Thermal L oads to be wr itten. Structural L oads contains optional str uctural loads tha t can b e wr itten t o AB AQUS, I-deas U niversal, Mechanic al APDL Input , NASTR AN, and P ATRAN files .This option is a vailable only when Structural analy sis is selec ted. Force enables f orce to be wr itten as a load f or a str uctural analy sis. Pressur e enables pr essur e to be wr itten as a load f or a str uctural analy sis. Temp erature enables t emp erature to be wr itten as a load f or a str uctural analy sis.This option is a vailable only when the Energy Equa tion is enabled . Thermal L oads contains optional ther mal loads tha t can b e wr itten t o AB AQUS, I-deas U niversal, Mechanic al APDL Input , NASTR AN, and P ATRAN files .This option is a vailable only when Thermal analy sis is selec ted. Temp erature enables t emp erature to be wr itten as a load f or a ther mal analy sis. Heat Flux enables hea t flux t o be wr itten as a load f or a ther mal analy sis. Heat Trans C oeff enables hea t transf er coefficien t to be wr itten as a load f or a ther mal analy sis. Location (for ASCII ,CGNS , and EnSight Case G old formats) specifies the lo cation fr om which the v alues of sc alar func tions ar e to be tak en. Node specifies tha t da ta values a t the no de p oints ar e to be exported. Cell C enter specifies tha t da ta values fr om the c ell c enters ar e to be exported. EnSight Parallel (Available only with F luen t in par allel) cr eates .encas files suitable f or use in EnS ight En terprise. Format (for CDA T for CFD-P ost & E nSight and EnSight Case G old) specifies the file f ormat. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3634Task P age R eference GuideBinar y specifies the file f ormat as binar y. ASCII specifies the file f ormat as ASCII. Heat Transf er C oefficien t (for TAITherm format only) specifies the basis f or the hea t transf er coefficien t exported. Flux B ased specifies the flux based metho d for wr iting the hea t transf er coefficien t. Wall F unc tion specifies the w all func tion based metho d for wr iting the hea t transf er coefficien t. Write Case F ile E very Time (for CDA T for CFD-P ost Y EnSight) specifies whether a c ase file is wr itten with e very .cdat file, or if c ase files ar e wr itten based on the settings specified b y the file/transient-export/settings/cdat-for-cfd-post-&-ensight text command . Export Data E very specifies the fr equenc y for app ending the da ta dur ing the solution pr ocess based on either Time S teps or Flow Time . File N ame specifies the r oot name f or the files t o be sa ved. Append F ile N ame with allows you t o selec t flow-time or time-st ep to be app ended t o the file name . Decimal P laces in F ile N ame allows you t o sp ecify the numb er of decimal digits in the file name .This option is a vailable only when flow-time is selec ted in the Append F ile N ame with drop-do wn list. The default v alue f or this field is set to 6. 47.16.4. Automa tic P article Hist ory Data E xport Dialo g Box The Automa tic P article Hist ory Data E xport dialo g box allo ws you t o cr eate an aut oma tic par ticle history export definition f or solution da ta. See Creating A utoma tic Exp ort Definitions f or Transien t Particle Hist ory Data (p.631) for details . 3635Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Calcula tion A ctivities Task P ageControls Name specifies the name of the par ticle hist ory export definition. File Type specifies the t ype of the file y ou w ant to wr ite. CFD-P ost allows you t o wr ite the file in CFD-P ost par ticle tr acks f ormat, which c an b e read in CFD-P ost. FieldVie w allows you t o wr ite the file in FIELD VIEW format, which c an b e read in FIELD VIEW. EnSight allows you t o wr ite the file in EnSight format. Injec tions allows you t o selec t the r equir ed injec tion fr om the list of pr edefined injec tions . Quan tity contains the list of v ariables f or which y ou c an e xport the par ticle da ta. Skip allows you t o “thin ” or “sample ” the numb er of par ticles tha t are exported. Frequenc y (Time S teps) or (DPM I terations) specifies the fr equenc y of par ticle time st eps tha t are used f or sa ving the e xport file . Separ ate Files f or E ach Time S tep allows you t o ha ve separ ate exported da ta files f or each time st ep. Available only when EnSight is selec ted as the File Type. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3636Task P age R eference GuideParticle F ile N ame allows you t o sp ecify the file name/dir ectory for the e xported da ta, using the Browse... butt on. Ensigh t Encas F ile N ame is the file name y ou will sp ecify if y ou selec ted EnSight under File Type. Use the Browse... butt on t o selec t the .encas file tha t was cr eated when y ou e xported the file with the File/E xport... ribbon tab option. 47.16.5. Execut e Commands D ialo g Box The Execut e Commands dialo g box allo ws you t o define c ommands t o be execut ed dur ing the c alcu- lation. See Executing C ommands D uring the C alcula tion (p.2660 ) for details ab out using this f eature. Controls Defined C ommands sets the t otal numb er of monit or commands t o be defined . Active activates/deac tivates the e xecution of each c ommand . Name specifies a name f or each c ommand . Every,When indic ate ho w of ten the c ommand is t o be execut ed.You c an en ter the in terval under Every and selec t Iteration ,Time S tep or Flow Time under When . (Time S tep and Flow Time are only v alid choic es if y ou are calcula ting unst eady flo w.) Command specifies the c ommand t o be execut ed.You c an en ter text commands or the name of a c ommand macr o that you ha ve defined in the Define M acro Dialog Box (p.3638 ). Define M acro... opens the Define M acro Dialog Box (p.3638 ), in which y ou c an define c ommand macr os. End M acro ends the definition of a macr o. (This butt on will r eplac e the Define M acro... butt on when y ou click OK in the Define M acro dialo g box.) 3637Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Calcula tion A ctivities Task P age47.16.6. Define M acro Dialo g Box The Define M acro dialo g box allo ws you t o define macr os for aut oma tic e xecution b y the c ommand monit or, or f or in teractive use b y you. See Defining M acros (p.2662 ) for details . Controls Macros contains a selec table list of the cur rently-defined macr os. Name specifies a name f or the c ommand macr o. 47.16.7. Automa tic S olution Initializa tion and C ase M odific ation D ialo g Box The Automa tic S olution Initializa tion and C ase M odific ation dialo g box allo ws you t o sp ecify the solution initializa tion metho d and t o mo dify the c ase. See Automa tic Initializa tion of the S olution and Case M odific ation (p.2664 ) for details . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3638Task P age R eference GuideControls Initializa tion M etho d tab c ontains se veral choic es for initializing the solution. Initializ e with Values fr om the C ase uses the v alues set in the Solution Initializa tion task page . Use S olution D ata F rom F ile requir es y ou t o read in a da ta file c ontaining the desir ed initializa tion f or the c ase. Use S olution D ata F rom P revious P arametr ic R un with Workbench (transien t cases only) r equir es y ou t o selec t one of t wo metho ds to initializ e the first r un.You c an Initializ e with Values fr om the C ase, which uses the v alues set in the Solution Initializa tion task page . Other wise , you c an Use S olution D ata fr om F ile, which r equir es y ou t o read in a da ta file containing the desir ed initializa tion f or the c ase. Use E xisting S olution D ata is analo gous t o changing the v alues in a c ase and c ontinuing the c alcula tion. However, the it eration coun ter will b e reset t o 0 so tha t the mo dific ations c an b e applied . Use this metho d when no solution data exists , similar t o the first r un. Case M odific ation allows you t o indic ate ho w long y ou w ould lik e to run with the or iginal settings , then mak e an y mo dific- ations t o the c ase settings . Defined M odific ations indic ates the numb er of mo dific ations f or the c ase file . Active allows you t o enable or disable a defined c ase mo dific ation. Name represen ts the name of the c ase mo dific ation. Commands represen ts an ar ea wher e you c an en ter text commands . 3639Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Calcula tion A ctivities Task P ageNumb er of I terations/T ime S teps represen ts the numb er of it erations or time st eps tha t you w ant to run defined c ase mo dific ation commands . Define M acro... opens the Define M acro Dialog Box (p.3638 ), in which y ou c an define c ommand macr os. 47.17. Run C alcula tion Task P age The Run C alcula tion task page allo ws you t o star t the solv er it erations . See Performing S teady-State Calcula tions (p.2614 ) and Performing Time-D ependen t Calcula tions (p.2626 ) for details ab out the it ems below. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3640Task P age R eference GuideControls Check C ase... opens the Case C heck D ialog Box (p.3647 ). Preview M esh M otion... opens the Mesh M otion D ialog Box (p.3599 ) for tr ansien t simula tions . Update Dynamic M esh... opens the Mesh M otion D ialog Box (p.3599 ) for st eady simula tions . 3641Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Run C alcula tion Task P agePseudo Transien t Settings is available f or fluid and solid z ones and will only app ear f or st eady-sta te cases , wher e the pr essur e-based coupled solv er is used . Note tha t the Pseudo Transien t option must b e enabled in the Solution M etho ds Task P age (p.3603 ). For details ab out the a vailable options , see Solving P seudo-T ransien t Flow (p.2622 ). Paramet ers (for st eady flo w calcula tions) c ontains settings f or running , reporting , and up dating the c alcula tion. Numb er of I terations sets the numb er of it erations t o be performed . Rep orting In terval sets the numb er of it erations tha t will pass b efore convergenc e monit ors will b e pr inted and plott ed. The default is 1 (tha t is, reports will b e up dated af ter each it eration). Profile U pdate In terval sets the numb er of it erations tha t will pass b efore user-defined func tions f or b oundar y pr ofiles will b e updated. Time A dvanc emen t (for tr ansien t flo w calcula tions) c ontains settings r elated t o time ad vancemen t. Type allows you t o sp ecify the t ype of time st epping fr om the f ollowing selec tions .The t ype you selec t will determine wha t fur ther selec tions ar e available in the Metho d drop-do wn list. Fixed specifies tha t the time st ep siz e is fix ed t o a user-sp ecified v alue or a v alue based on a sp ecified period or fr equenc y. Adaptiv e specifies tha t the time st ep siz e changes dur ing the solution, in or der t o either sa tisfy the C our- ant–Friedr ichs–L ewy (CFL) c ondition, main tain a c ertain tr uncation er ror asso ciated with the time integration scheme , or sa tisfy cr iteria tha t is sp ecific f or multiphase simula tions . User-D efined F unc tion specifies tha t the time st ep siz e is defined b y a user-defined func tion tha t uses the DEFINE_DELTAT macr o. Metho d allows you t o selec t one of the f ollowing , to sp ecify ho w the time st ep is det ermined: User-S pecified (for the Fixed type) selec ts a fix ed time st ep, equal t o the sp ecified Time S tep S ize. Period-B ased (for the Fixed type) allo ws you t o sp ecify a p eriod (in sec onds) as the basis f or det ermining the time st ep siz e and numb er of time st eps. See User Inputs f or Time-D ependen t Problems (p.2627 ) for details . Frequenc y-Based (for the Fixed type) allo ws you t o sp ecify a fr equenc y (in her tz) as the basis f or det ermining the time st ep siz e and numb er of time st eps. See User Inputs f or Time-D ependen t Problems (p.2627 ) for details . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3642Task P age R eference GuideCFL-B ased (for the Adaptiv e type) selec ts a time st ep tha t gets mo dified b y ANSY S Fluen t as the c alcula tion proceeds such tha t the C ourant–Friedr ichs–L ewy (CFL) c ondition is sa tisfied , using the sp ecified Cour ant Numb er. See CFL-B ased Time S tepping (p.2640 ) for details . Error-B ased (for the Adaptiv e type) selec ts a time st ep tha t gets mo dified b y ANSY S Fluen t based on the specified tr uncation Error Toler anc e. See Error-B ased Time S tepping (p.2642 ) for details . Multiphase-S pecific (for the Adaptiv e type) selec ts a time st ep tha t gets mo dified b y ANSY S Fluen t based on the convective time sc ale ( Global C our ant Numb er): the time-st ep-siz e calcula tion dep ends on the mesh densit y and v elocity in in terfacial c ells.This metho d is a vailable f or all multiphase mo dels using the implicit or e xplicit v olume fr action f ormula tion, except f or the w et st eam mo del. See Multiphase-S pecific Time S tepping (p.2643 ) for details . Duration S pecific ation M etho d (for the Adaptiv e or User-D efined F unc tion type) sp ecifies the w ay in which y ou will define the c al- cula tion dur ation. The dur ation c an b e defined b y the t otal time , the t otal numb er of time st eps, the incremen tal time , or the numb er of incr emen tal time st eps. In this c ontext, "total" indic ates tha t Fluen t will c onsider the amoun t of time / st eps tha t ha ve alr eady been solv ed and st op appr opriately, wher eas "incr emen tal" indic ates tha t the solution will pr oceed f or a sp ecified amoun t of time / st eps regar dless of wha t has pr eviously b een c alcula ted. Paramet ers (for tr ansien t flo w calcula tions) c ontains settings f or running , reporting , and up dating the c alcula tion. Numb er of Time S teps sets or r eports the numb er of time st eps t o be performed . Period sets or r eports the p eriod to be used in time st ep c alcula tion. Frequenc y sets or r eports the fr equenc y to be used in time st ep c alcula tion. Time S teps p er P eriod sets the numb er of time st eps t o divide each p eriod in to. Total P eriods sets the numb er of p eriods for the simula tion t o run. Total Time sets the t otal time tha t will b e calcula ted, including the time f or which r esults w ere gener ated during pr evious c alcula tions . Total N umb er of Time S teps sets the t otal numb er of time st eps t o be performed , including the numb er of time st eps p erformed in pr evious c alcula tions . Incr emen tal Time sets the incr emen tal time (tha t is, the additional time) f or which r esults ar e to be calcula ted. Time S tep S ize sets or r eports the magnitude of the (ph ysical) time st ep . 3643Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Run C alcula tion Task P ageCour ant Numb er allows you t o sp ecify the C ourant numb er for CFL-based time st epping .The default v alue f or the Cour ant numb er is 1. Error Toler anc e specifies the thr eshold v alue t o which the c omput ed tr uncation er ror is c ompar ed as par t of er ror- based time st epping . Incr easing this v alue will lead t o an incr ease in the siz e of the time st ep and a reduc tion in the accur acy of the solution. Decreasing it will lead t o a r educ tion in the siz e of the time st ep and an incr ease in the solution accur acy, although the c alcula tion will r equir e mor e computa tional time . For most c ases , the default v alue of 0.01 is acc eptable . Global C our ant Numb er allows you t o sp ecify the global C ourant numb er for multiphase-sp ecific time st epping .The default value f or the Global C our ant numb er is 2. User-D efined Time S tep contains a dr op-do wn list of a vailable user-defined func tions (UDFs) tha t can b e used t o define the time st ep siz e. Numb er of F ixed Time S teps specifies the numb er of fix ed-siz e time st eps tha t should b e performed b efore the siz e of the time step star ts to change .The siz e of the fix ed time st ep is the v alue sp ecified f or Initial Time S tep Size. Initial Time S tep S ize is used f or the first time st ep and then f or as man y subsequen t steps as sp ecified in the Numb er of F ixed Time S teps field .This v alue must fall b etween the minimum and maximum time st ep sizes. For a b etter star tup, it should b e chosen such tha t the C ourant numb er initially r emains close to 1 or y our sp ecified v alue (whiche ver is lo wer). Note tha t if y ou initializ e the solution f or a pr evi- ously r un c ase with adaptiv e time st epping , then ANSY S Fluen t will use the time st ep siz e sa ved in the c ase. Max I terations/T ime S tep (when using an implicit unst eady formula tion) sets the maximum numb er of it erations t o be per- formed p er time st ep. If the c onvergenc e criteria ar e met b efore this numb er of it erations is p er- formed , the solution will ad vance to the ne xt time st ep. See User Inputs f or Time-D ependen t Problems (p.2627 ) for details . Rep orting In terval sets the numb er of time st eps tha t will pass b efore convergenc e monit ors will b e pr inted and plott ed.The default is 1 (tha t is, reports will b e up dated af ter each time st ep). Profile U pdate In terval sets the numb er of time st eps tha t will pass b efore user-defined func tions f or b oundar y pr ofiles will b e up dated. Time S tep S ize Update In terval specifies the numb er of time st eps tha t will pass b efore the time st ep siz e is up dated f or adaptiv e time st epping metho ds. Settings ... opens the Adaptiv e Time S tepping D ialog Box (p.3648 ), so tha t you c an define fur ther settings f or the adaptiv e time st epping metho d. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3644Task P age R eference GuideOptions contains options r elated t o unst eady calcula tions . Extrapolate Variables instr ucts ANSY S Fluen t to pr edic t the solution v ariable v alues f or the ne xt time st ep and then input that predic ted v alue as an initial guess f or the inner it erations of the cur rent time st ep. Rep ort Simula tion S tatus opens the Simula tion S tatus D ialog Box (p.3649 ), which r eports details ab out the simula tion. Specify S olid Time S tep S ize enables a diff erent time st ep siz e to be sp ecified f or solid z ones , either user sp ecified or aut oma tically calcula ted.This option is only a vailable when ther e is a solid z one in the domain and ener gy is enabled . See Specifying a S olid Time st ep (p.1471 ) for details . Metho d specifies ho w the time st ep siz e is det ermined f or solid z ones . Time S tep S ize specifies the time st ep siz e for solid z ones when y ou ha ve selec ted User-S pecified for the Metho d. Options contains options f or st eady-sta te simula tions tha t use the densit y-based implicit solv er. Solution S teering allows you t o set par amet ers tha t will help ANSY S Fluen t guide the c alcula tions t o a c onverged solution. This option is only a vailable f or st eady-sta te simula tions tha t use the densit y-based implicit solv er. See Solution S teering (p.2698 ) for mor e inf ormation. When enabled , the f ollowing options ar e available: Flow Type allows you t o selec t the flo w type tha t best descr ibes the flo w in the solution domain. Five choic es ar e available: incompr essible ,subsonic ,transonic ,sup ersonic , and hypersonic . Use FMG Initializa tion allows for full multigr id initializa tion. First- t o Higher-Or der Blending allows you t o reduc e the desir ed solution accur acy by selec ting a blending fac tor less than 100%. The default setting is 100%. See First- t o Higher-Or der B lending in the Theor y Guide for mor e inf ormation. The blending fac tor will b e gr ayed out if Second Or der U pwind discr etiza tion f or the Flow equa tions is not selec ted in the Solution M etho ds task page .The solution accur acy ma y be reduc ed (t ypic al values ar e 75% or 50%) if it is not p ossible t o obtain a c onverged solution with the maximum sec ond- order accur acy (blending = 100%). More Settings ... opens the Solution S teering D ialog Box (p.3650 ). Cour ant Numb er is a non-adjustable field displa ying the cur rent CFL numb er, which allo ws you t o view it dur ing the calcula tion. Solution P rocessing contains c ontrols r elated t o the pr ocessing of the c alcula tions . 3645Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Run C alcula tion Task P ageAcoustic contains c ontrols f or simula tions tha t use the FW-H ac oustics mo del. Time S tep S ize for A coustic D ata E xport determines the highest fr equenc y tha t the ac oustic analy sis r eproduces.This is a vailable f or the densit y-based solv er when b oth the e xplicit f ormula tion and e xplicit tr ansien t formula tion ar e se- lected. Acoustic S our ces FFT ... opens the Acoustic S ources FFT D ialog Box (p.3652 ).This butt on is only a vailable f or thr ee-dimen- sional tr ansien t simula tions , when the Export Acoustic S our ce Data in ASD F ormat option is enabled in the Acoustics M odel dialo g box. Acoustic S ignals ... opens the Acoustic S ignals D ialog Box (p.3657 ). Pollutan ts contains c ontrols f or simula tions tha t mo del p ollutan t formation. Postpr ocess P ollutan ts results in the aut oma tic p ostpr ocessing of p ollutan ts dur ing a tr ansien t simula tion. Max P ost I terations/T ime S tep sets the maximum numb er of p ostpr ocessing it erations t o be performed p er time st ep.This field is available when the Postpr ocess P ollutan ts option is enabled . PDF Transp ort Time A veraging contains solution c ontrols f or st eady-sta te simula tions tha t use the c omp osition PDF tr ansp ort mo del with the Lagr angian metho d. Iterations in A verage specifies the numb er of it erations included in the PDF tr ansp ort time a veraging . For recommend- ations on ho w to use this setting , see Monit oring the S olution (p.1787 ). Iteration Incr emen t specifies the r ate at which the numb er of it erations included in the PDF tr ansp ort time a veraging will incr ease in each subsequen t iteration. For recommenda tions on ho w to use this setting , see Monit oring the S olution (p.1787 ). Statistics contains c ontrols f or sampling sta tistics . Data S ampling f or S tead y Statistics enables the sampling of da ta dur ing a st eady-sta te calcula tion. See Performing S teady-State Calcu- lations (p.2614 ) and Postpr ocessing f or Time-D ependen t Problems (p.2645 ) for details . Data S ampling f or Time S tatistics enables the sampling of da ta dur ing an unst eady calcula tion. See User Inputs f or Time-D ependen t Problems (p.2627 ) and Postpr ocessing f or Time-D ependen t Problems (p.2645 ) for details . Sampling In terval allows you t o sp ecify the fr equenc y of the Data S ampling f or S tead y Statistics or Data S ampling for Time S tatistics . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3646Task P age R eference GuideSampled I terations reports the numb er of it erations o ver which da ta has b een sampled f or the p ostpr ocessing of the mean and RMS v alues . Sampled Time reports the time p eriod over which da ta has b een sampled f or the p ostpr ocessing of the mean and RMS v alues . Sampling Options ... opens the Sampling Options D ialog Box (p.3659 ) for the Data S ampling f or S tead y Statistics or Data S ampling f or Time S tatistics . Data F ile Q uan tities ... opens the Data File Q uan tities D ialog Box (p.3630 ). Solution A dvanc emen t contains butt ons tha t ad vance the solution. Calcula te starts the c alcula tions .While the c alcula tion is in pr ogress, a pr ogress bar will app ear a t the b ottom of the F luen t windo w. For st eady-sta te simula tions , click ing the Stop butt on ne xt to the pr ogress bar will interrupt the c alcula tion a t the ear liest saf e stopping p oint after the cur rent iteration; for tr ansien t simula tions , butt ons ar e available tha t allo w you t o stop the c alcula tion a t the end of the cur rent iter- ation or time st ep. Alternatively, you c an t ype Ctrl+c in the c onsole; for tr ansien t simula tions , a single instanc e will st op the c alcula tion a t the end of the cur rent time st ep, wher eas t yping it t wice will st op it at the end of the cur rent iteration. Continue C alcula tion continues the c alcula tions .This butt on is a vailable when y ou ha ve enabled the Automa tically Initializ e and M odify C ase option in the Calcula tion A ctivities task page . Start Calcula tion O ver restar ts the c alcula tion fr om the b eginning .This butt on is a vailable when y ou ha ve enabled the Automa tically Initializ e and M odify C ase option in the Calcula tion A ctivities task page . For additional inf ormation, see the f ollowing sec tions: 47.17.1. Case C heck D ialog Box 47.17.2. Adaptiv e Time S tepping D ialog Box 47.17.3. Simula tion S tatus D ialog Box 47.17.4. Solution S teering D ialog Box 47.17.5. Acoustic S ources FFT D ialog Box 47.17.6. Acoustic S ignals D ialog Box 47.17.7. Sampling Options D ialog Box 47.17.1. Case C heck D ialo g Box This func tion pr ovides y ou with guidanc e and b est pr actices when cho osing c ase par amet ers and models .Your c ase will b e check ed f or c omplianc e in the mesh, mo dels , boundar y and c ell z one c ondi- tions , ma terial pr operties, and solv er categor ies. Established r ules ar e available f or each c ategor y, with recommended changes t o your cur rent settings . Information ab out each of the r ecommenda tions is available in Check ing Your C ase S etup (p.2677 ). 3647Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Run C alcula tion Task P ageControls Mesh displa ys recommenda tions , if an y, relating the t o the mesh used in the c ase. See Check ing the M esh (p.2680 ) for details . Models displa ys recommenda tions , if an y, relating the t o the mo dels used in the c ase. See Check ing M odel S elec- tions (p.2682 ) for details . Boundar ies and C ell Z ones displa ys recommenda tions , if an y, relating the t o the c ell z ones or b oundar ies defined in the c ase. See Check ing B oundar y and C ell Z one C onditions (p.2684 ) for details . Materials displa ys recommenda tions , if an y, relating the t o the ma terials defined in the c ase. See Check ing M aterial Properties (p.2687 ) for details . Solver displa ys recommenda tions , if an y, relating the t o the solv er settings used in the c ase. See Check ing the Solver Settings (p.2688 ) for details . 47.17.2. Adaptiv e Time S tepping D ialo g Box The Adaptiv e Time S tepping dialo g box pr ovides additional settings tha t aff ect the adaptiv e time stepping . See Performing Time-D ependen t Calcula tions (p.2626 ) for details ab out adaptiv e time st epping . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3648Task P age R eference GuideControls Minimum/M aximum Time S tep S ize specify the upp er and lo wer limits f or the siz e of the time st ep. If the time st ep b ecomes v ery small, the computa tional e xpense ma y be too high; if the time st ep b ecomes v ery lar ge, the solution accur acy ma y not b e acc eptable t o you.You c an set the limits tha t are appr opriate for y our simula tion. Minimum/M aximum S tep C hange F actor limit the degr ee to which the time st ep siz e can change a t each time st ep. Limiting the change r esults in a smo other c alcula tion of the time st ep siz e, esp ecially when high-fr equenc y noise is pr esen t in the solution. For the CFL-B ased and Multiphase-S pecific metho ds, the time st ep change fac tor is c omput ed as the r atio b etween the cur rent time st ep and the pr evious time st ep. For the Error-B ased metho d, the time st ep change fac tor is c omput ed as the r atio b etween the sp ecified tr uncation er ror toler ance and the c omput ed tr uncation er ror. 47.17.3. Simula tion S tatus D ialo g Box The Simula tion S tatus dialo g box reports details ab out the simula tion. 3649Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Run C alcula tion Task P ageControls Time S tep S ize (for adaptiv e time st epping) r eports the siz e of the last time st ep c alcula ted f or the simula tion. Total F low Time reports the t otal time c alcula ted f or the simula tion. Total Time S teps reports the numb er of time st eps c alcula ted f or the simula tion. Total I terations reports the numb er of it erations c alcula ted f or the simula tion. Minimum Time S tep S ize (for adaptiv e time st epping) r eports the siz e of the smallest time st ep used sinc e either the star t of the simula tion or the last time y ou click ed the Calcula te butt on in the Run C alcula tion task page , dep ending on whether y ou ha ve click ed the Reset M in and M ax S tatus butt on. Maximum Time S tep S ize (for adaptiv e time st epping) r eports the siz e of the lar gest time st ep used sinc e either the star t of the simula tion or the last time y ou click ed the Calcula te butt on in the Run C alcula tion task page , dep ending on whether y ou ha ve click ed the Reset M in and M ax S tatus butt on. Reset M in and M ax S tatus (for adaptiv e time st epping) r esets the Minimum Time S tep S ize and Maximum Time S tep S ize fields , so tha t the y consider only the v alues sinc e the la test time y ou click ed the Calcula te butt on in the Run Calcula tion task page . 47.17.4. Solution S teering D ialo g Box The Solution S teering dialo g box is used t o set the par amet ers tha t control the solution st eering strategy. Solution st eering will t ypic ally p erform full multigr id (FMG) initializa tion f ollowed b y two iter- Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3650Task P age R eference Guideative stages (S tage 1 and S tage 2). The pur pose of S tage 1 is t o na viga te the solution fr om the difficult initial phase of the solution t oward convergenc e by insur ing maximum stabilit y. During this stage , the solution is ad vanced gr adually fr om 1st-or der accur acy to maximum accur acy (user sp ecified and t yp- ically 2nd-or der) a t a c onstan t low CFL v alue . In S tage 2, the solution is dr iven har d towards c onvergenc e by regular adjustmen ts of the CFL v alue t o insur e fast c onvergenc e as w ell as t o pr event possible di- vergenc e. In S tage 2, the r esidual hist ory is monit ored and analyz ed thr ough r egular in tervals t o de- termine if an incr ease or decr ease in CFL v alue is needed t o obtain fast c onvergenc e or t o pr event divergenc e. See Solution S teering (p.2698 ) for details . Controls Steering S ettings allows you t o mo dify the st eering par amet ers used in S tages 1 and 2. Stage 1 allows you t o set par amet ers r elating t o stage 1. Duration is the numb er of it erations in stage 1. The CFL numb er used dur ing these it erations is set in the Initial field , in the Cour ant Numb er group b ox. Stage 2 allows you t o set par amet ers r elating t o stage 2. Update the C our ant Numb er allows you t o up date the C ourant numb er either Immedia tely, or After a sp ecified numb er of iterations . 3651Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Run C alcula tion Task P ageCour ant Numb er U pdate In terval defines the fr equenc y at which the C ourant numb er is up dated. Cour ant Numb er allows you t o set the star ting ( Initial ) and maximum allo wed ( Maximum ) Courant numb er values . The solution st eering algor ithm will not allo w the solv er to exceed the maximum C ourant numb er, but will allo w the solv er to use a C ourant numb er less than the initial C ourant numb er if div ergenc e in the solution has o ccur red. Explicit U nder-Relaxa tion F actor allows the solution t o be under-r elax ed t o impr ove convergenc e. Default resets an y changes made t o the par amet ers t o their or iginal default v alues . FMG S ettings allows you t o set FMG par amet ers. For mor e inf ormation ab out FMG initializa tion, refer to Full M ultigr id (FMG) Initializa tion (p.2609 ). Numb er of M ultigr id L evels allows you t o set the numb er of multigr id le vels. Numb er of C ycles allows you t o set the numb er of c ycles f or a selec ted le vel. FMG C our ant Numb er allows you t o set the FMG C ourant numb er. Default resets an y changes t o the or iginal default v alues . 47.17.5. Acoustic S our ces FFT D ialo g Box The Acoustic S our ces FFT dialo g box allo ws you t o: read pr essur e signals fr om the ac oustic sour ce data (ASD) files (see Writing S ource Data Files (p.1882 )); comput e Fourier sp ectra of these signals a t the selec ted p oint probes and o ver the en tire sour ce zones; create sur face variables f or visualizing the spectral pr operties of the flo w pr essur e signals; and wr ite CGNS files of the sp ectrum da ta. See FFT of Acoustic S ources: Band A naly sis and Exp ort of Sur face Pressur e Spectra (p.1894 ) for details ab out the items b elow. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3652Task P age R eference GuideControls Storage A rea C ontrol allows you t o sp ecify ho w memor y is allo cated in the “storage ar ea” (tha t is, the lar ge memor y array tha t stores the fields of the pr essur e hist ories and the c omput ed fields of the F ourier sp ectra) when y ou comput e the FFT fields in the Comput e FFT F ields tab . Overwrite Signals b y Spectra specifies tha t the F ourier sp ectra displac e in memor y the or iginal time signals , so tha t the y are not kept af ter the FFT has b een c omput ed. Clean U p Only FFT Results de-allo cates the st orage ar ea—so tha t you c an r e-comput e the FFT without r e-reading the pr essur e histories—and delet es all v ariables cr eated thr ough the FFT S urface Variables tab .This butt on is only a vailable when the Overwrite Signals b y Spectra option is disabled . Clean U p Entire Storage A rea de-allo cates the st orage ar ea—so tha t you c an r e-read ASD files and r e-comput e the FFT with a clipp ed time r ange or diff erent windo w func tion—and delet es all v ariables cr eated thr ough the FFT S urface Variables tab . Point Probes f or Time S ignals allows you t o get inf ormation ab out e xisting p oint probes and cr eate pr essur e hist ory files . Existing P oints lists all of the p oint probes cr eated thr ough the Point Sur face Dialog Box (p.3898 ) tha t are available f or selec tion. Print Coordina tes prints in the c onsole the c oordina tes of the p oint probe(s) selec ted in the Existing P oints selec tion list. 3653Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Run C alcula tion Task P ageExtract Signals creates ASCII files tha t contain the pr essur e hist ories of the p oint probe(s) selec ted in the Existing Points selec tion list. File N ame specifies a pr efix f or the names of the files cr eated b y the Extract Signals butt on. Read ASD F iles allows you t o read pr essur e hist ories fr om the ac oustic sour ce da ta (ASD) files . Active Sour ce Zones is a list of the fac e zones f or which y ou c an r ead ac oustic sour ce da ta. Sour ce Data F iles is a list of the ASD files y ou c an r ead. Load Inde x File... updates the Active Sour ce Zones and Sour ce Data F iles lists b y loading an ASCII inde x file . Read reads the pr essur e signals fr om the selec ted it ems in the Active Sour ce Zones and Sour ce Data F iles lists . Comput e FFT F ields allows you t o comput e FFT fields fr om the pr essur e signals r ead thr ough the Read ASD F iles tab . Sampling D ata allows you t o reduc e the time r ange of the signal da ta used t o comput e the FFT fields . Clip Time t o Range specifies tha t the time r ange of the da ta sampled is r educ ed t o be between the Min and Max. Min specifies the minimum v alue of the time r ange of the signal da ta when the Clip Time t o Range option is enabled . Max specifies the maximum v alue of the time r ange of the signal da ta when the Clip Time t o Range option is enabled . Time S tep reports the siz e of the time st ep a t which da ta w as sampled . Re-E stima te Spectral Resolution updates the v alues tha t are displa yed in the Spectral Resolution group b ox and tha t are used to comput e the FFT fields , based on the settings in the Sampling D ata group b ox. Spectral Resolution displa ys the numb er of samples and the e xpected sp ectrum pr operties f or the pr ovided signals . Numb er of S amples reports the t otal numb er of samples in the sp ecified time r ange . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3654Task P age R eference GuideSamples U sed f or FFT reports the numb er of samples tha t will b e used f or FFT (see Table 40.2: Numb ers of D ata Points Supp orted b y the P rime-F actor FFT A lgor ithm (p.2900 )). Frequenc y M in & S tep reports the e xpected minimum fr equenc y in the sp ectrum, which is also the e xpected fr equenc y step. Frequenc y M ax reports the e xpected maximum fr equenc y in the sp ectrum. Numb er of M odes reports the e xpected numb er of F ourier mo des in the sp ectrum. Windo w Func tion specifies the shap e of the windo w func tion used t o enf orce the signal's p eriodicit y. See Windo w- ing (p.2898 ) for details .The default is the Hanning windo w. Comput e comput es the FFT fields based on the settings in the Comput e FFT F ields tab . FFT S urface Variables allows you t o create new F luen t variables f or p ostpr ocessing using the sp ectrum fields c omput ed thr ough the Comput e FFT F ields tab . Modes/F requenc y Bands specifies wha t the cr eated v ariables will char acterize. Octave Bands specifies tha t the v ariables char acterize pr oportional fr equenc y bands c orresponding t o the standar d technic al octaves. 1/3 O ctave Bands specifies tha t the v ariables char acterize pr oportional fr equenc y bands c orresponding t o the standar d technic al thir ds. Constan t Width B ands specifies tha t the v ariables char acterize user-defined equidistan t frequenc y bands . Set of M odes specifies tha t the v ariables char acterize the individual F ourier mo des. Octave Central F requencies is a list of the o ctave central frequencies f or which y ou c an Create Fluen t variables f or p ostpr ocessing . This selec tion list is a vailable when Octave Bands is selec ted fr om the Modes/F requenc y Bands drop-do wn list. 1/3-O ctave Central F requencies is a list of the 1/3-o ctave central frequencies f or which y ou c an Create Fluen t variables f or p ostpr o- cessing .This selec tion list is a vailable when 1/3-O ctave Bands is selec ted fr om the Modes/F requenc y Bands drop-do wn list. 3655Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Run C alcula tion Task P ageFrequenc y M in specifies the minimum fr equenc y of the set of mo des f or which y ou w ant to Create Fluen t variables for p ostpr ocessing .This field is a vailable when Set of M odes or Constan t Width B ands is selec ted from the Modes/F requenc y Bands drop-do wn list. Frequenc y M ax specifies the maximum fr equenc y of the set of mo des f or which y ou w ant to Create Fluen t variables for p ostpr ocessing .This field is a vailable when Set of M odes or Constan t Width B ands is selec ted from the Modes/F requenc y Bands drop-do wn list. Numb er of M odes t o Skip allows you t o “thin ” or “sample ” the mo des f or which y ou w ant to Create the F luen t variables f or postpr ocessing .This field is a vailable when Set of M odes is selec ted fr om the Modes/F requenc y Bands drop-do wn list. Band Width specifies the width of the c onstan t width bands , for which y ou w ant to Create the F luen t variables for p ostpr ocessing .This field is a vailable when Constan t Width B ands is selec ted fr om the Modes/F requenc y Bands drop-do wn list. Spectrum P roperty displa ys the t ype of v ariables cr eated acc ording t o the selec ted choic e in the Modes/F requenc y Bands drop-do wn list. Surface Pressur e Level is displa yed when fr equenc y band is selec ted fr om the Modes/F requenc y Bands drop-do wn list , in or der t o indic ate tha t the cr eated v ariables will b e the sur face pr essur e level (SPL) fields , in decib els. Real and Imaginar y Amplitude P arts is displa yed when Set of M odes is selec ted fr om the Modes/F requenc y Bands drop-do wn list , in or der t o indic ate tha t the cr eated v ariables will b e the r eal and imaginar y par ts of the c omple x Fourier amplitudes , with a pair of v ariables p er sp ecified mo de. Existing Variables lists the pr ocessed v ariables tha t ha ve been cr eated b y the Create butt on, and allo ws you t o mak e selec tions f or deletion using the Remo ve Selec ted Variables butt on. Remo ve Selec ted Variables delet es the pr ocessed v ariables selec ted in the Existing Variables list fr om the “storage ar ea” (as descr ibed pr eviously), so tha t you c an analyz e mor e than the maximum of 20 individual mo des or constan t width bands tha t are allo wed t o exist a t an y one time . Write Area-A vg D ata When selec ted, and up on click ing Create, Fluen t wr ites the ar ea-a veraged pr essur e da ta to an ASCII file in the X Y plot file f ormat. Plot A rea-A vg D ata When selec ted, and up on click ing Create, Fluen t plots the ar ea-a veraged pr essur e da ta in the f orm of a bar char t in the gr aphics windo w. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3656Task P age R eference GuideCreate creates new F luen t variables f or p ostpr ocessing (based on y our settings in the FFT S urface Variables tab), updates the Existing Variables selec tion list , and (when Set of M odes or Constan t Width B ands is selec ted fr om the Modes/F requenc y Bands drop-do wn list) pr ints inf ormation in the c onsole . Write CGNS F iles allows you t o wr ite CGNS files of the sp ectrum da ta. Processed S our ce Zones is a list of the z ones y ou c an e xport. Frequenc y Series allows you t o reduc e the e xported sp ectrum da ta. Reduc e Frequenc y Series specifies tha t the e xported sp ectrum da ta is r educ ed t o be between the Min and Max. Min specifies the minimum of the fr equenc y range t o be exported when the Reduc e Frequenc y Series option is enabled . Max specifies the maximum of the fr equenc y range t o be exported when the Reduc e Frequenc y Series option is enabled . Numb er of F requencies t o Skip allows you t o “thin ” or “sample ” the fr equencies t o be exported. Numb er of F requencies p er F ile specifies the numb er of fr equencies e xported in each file . A value should b e chosen based on the Numb er of M odes field of the Comput e FFT F ields tab , in or der t o avoid cr eating either e xtremely large output files or a lar ge numb er of v ery small files . File N ame specifies the base file name of the output files . Write writes C GNS files of the sp ectrum da ta. 47.17.6. Acoustic S ignals D ialo g Box The Acoustic S ignals dialo g box is used t o comput e and sa ve the sound pr essur e signals . See Postpr o- cessing the FW-H A coustics M odel D ata (p.1891 ) for details ab out the it ems b elow. 3657Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Run C alcula tion Task P ageControls Options contains the options a vailable f or ac oustic signal p ostpr ocessing . Write Acoustic S ignals enables the par amet ers needed t o wr ite the sound pr essur e da ta to files . Read U nstead y Acoustic S our ce Data F iles enables the par amet ers needed t o comput e the sound pr essur e signals using the sour ce da ta sa ved to files . Active Sour ce Zones contains sour ce zones y ou w ant to include t o comput e sound . See Specifying S ource Sur faces (p.1884 ) for details . Rec eivers contains all the r eceivers f or which y ou c an c omput e sound . Sour ce Data F iles contains all the sour ce da ta files tha t you c an use t o comput e sound . Load Inde x File... opens the Selec t File dialo g box, in which y ou c an selec t the inde x file f or y our c omputa tion. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3658Task P age R eference GuideWrite writes the sound pr essur e da ta.This butt on will app ear only when Write Acoustic S ignals is selec ted under Options . Comput e/W rite comput es and sa ves the sound pr essur e da ta.This butt on will app ear only when Read U nstead y Acoustic S our ce Data F iles is selec ted under Options . Rec eivers... opens the Acoustic R eceivers D ialog Box (p.3376 ) in which y ou c an define additional r eceivers. 47.17.7. Sampling Options D ialo g Box The Sampling Options dialo g box allo ws you t o sp ecify a c ollec tion of sta tistics f or:Flow S hear Stresses ,Flow H eat Fluxes,Wall S tatistics ,DPM Variables , and Custom F ield F unc tions . Controls Collec t Statistics f or... contains options f or the v ariables y ou w ant to be able t o postpr ocess. Flow S hear S tresses allows you t o enable or disable the flo w shear str ess sta tistics f or p ostpr ocessing . Flow H eat Fluxes allows you t o enable or disable the flo w hea t flux es sta tistics f or p ostpr ocessing . Wall S tatistics allows you t o enable or disable the w all sta tistics f or p ostpr ocessing . 3659Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Run C alcula tion Task P ageDPM Variables allows you t o enable or disable DPM v ariable sta tistics f or p ostpr ocessing . Custom F ield F unc tions allows you t o selec t the pr eviously defined cust om field func tions y ou w ant to be able t o postpr ocess. 47.18. Results Task P age The Results task page in troduces y ou t o the main tasks in volved in setting up and displa ying the r esults of y our CFD simula tion using ANSY S Fluen t. 47.19. Graphics and A nima tions Task P age The Graphics and A nima tion task page allo ws you t o visualiz e the r esults of y our CFD simula tion b y allowing y ou t o set up plots of c ontours , vectors, pathlines , par ticle tr acks , scene descr iptions and an- imations . See Displa ying G raphics (p.2775 ) for mor e inf ormation. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3660Task P age R eference GuideControls Graphics displa ys a list of the a vailable gr aphics objec ts. You c an double-click an it em in the Graphics list t o op en the c orresponding dialo g box, or y ou c an selec t the it em in the list and click the Set U p... butt on. Mesh - selec ting this it em and click ing the Set U p... butt on op ens the Mesh D ispla y Dialog Box (p.3239 ). Contours - selec ting this it em and click ing the Set U p... butt on op ens the Contours D ialog Box (p.3790 ). Vectors - selec ting this it em and click ing the Set U p... butt on op ens the Vectors D ialog Box (p.3954 ). Pathlines - selec ting this it em and click ing the Set U p... butt on op ens the Pathlines D ialog Box (p.3891 ). Particle Tracks - selec ting this it em and click ing the Set U p... butt on op ens the Particle Tracks D ialog Box (p.3881 ). Set U p... opens the dialo g box corresponding t o the selec ted objec t in the Graphics list. 3661Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Graphics and A nima tions Task P ageAnima tions displa ys a list of the a vailable anima tion objec ts. You c an double-click an it em in the Anima tions list t o op en the c orresponding dialo g box, or y ou can selec t the it em in the list and click the Set U p... butt on. Sweep S urface - selec ting this it em and click ing the Set U p... butt on op ens the Sweep Sur face Dialog Box (p.3672 ). Scene A nima tion - selec ting this it em and click ing the Set U p... butt on op ens the Anima te Dialog Box (p.3674 ). Solution A nima tion - selec ting this it em and click ing the Set U p... butt on op ens the Playback D ialog Box (p.3679 ). Set U p... opens the dialo g box corresponding t o the selec ted objec t in the Anima tions list. Options ... opens the Displa y Options D ialog Box (p.3681 ). Scene ... opens the Scene D escr iption D ialog Box (p.3683 ). Views... opens the Views Dialog Box (p.3690 ). Ligh ts... opens the Ligh ts D ialog Box (p.3696 ). Color map ... opens the Color map D ialog Box (p.3697 ). Annota te... opens the Annota te Dialog Box (p.3700 ). For additional inf ormation, see the f ollowing sec tions: 47.19.1. Profile Options D ialog Box 47.19.2. Vector Options D ialog Box 47.19.3. Custom Vectors D ialog Box 47.19.4. Vector D efinitions D ialog Box 47.19.5. Path Style A ttribut es D ialog Box 47.19.6. Ribbon A ttribut es D ialog Box 47.19.7. Particle F ilter A ttribut es 47.19.8. Reporting Variables D ialog Box 47.19.9. Track S tyle A ttribut es D ialog Box 47.19.10. Particle S pher e Style A ttribut es D ialog Box 47.19.11. Particle Vector Style A ttribut es D ialog Box 47.19.12. Sweep Sur face Dialog Box 47.19.13. Create Sur face Dialog Box 47.19.14. Anima te Dialog Box 47.19.15. Save Picture Dialog Box 47.19.16. Playback D ialog Box 47.19.17. Displa y Options D ialog Box Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3662Task P age R eference Guide47.19.18. Scene D escr iption D ialog Box 47.19.19. Displa y Properties D ialog Box 47.19.20. Transf ormations D ialog Box 47.19.21. Iso-V alue D ialog Box 47.19.22. Pathline A ttribut es D ialog Box 47.19.23. Bounding F rame D ialog Box 47.19.24. Views Dialog Box 47.19.25. Write Views Dialog Box 47.19.26. Mirror P lanes D ialog Box 47.19.27. Graphics P eriodicit y Dialog Box 47.19.28. Camer a Paramet ers D ialog Box 47.19.29. Ligh ts D ialog Box 47.19.30. Color map D ialog Box 47.19.31. Color map E ditor D ialog Box 47.19.32. Annota te Dialog Box 47.19.1. Profile Options D ialo g Box The Profile Options dialo g box controls the sc aling and pr ojec tion dir ection of pr ofiles . It is op ened from the Contours D ialog Box (p.3790 ), and y ou will displa y the pr ofiles using the Displa y butt on in that dialo g box. See Displa ying C ontours and P rofiles (p.2784 ) for details ab out the it ems b elow. Controls Referenc e Value sets the “zero heigh t” reference value f or the pr ofile . Any point on the pr ofile with a v alue equal t o the Referenc e Value will b e plott ed e xactly on the defining sur face.Values gr eater than the Referenc e Value will b e pr ojec ted ahead of the sur face (in the dir ection of Projec tion D ir. and sc aled b y Scale F actor), and v alues less than the Referenc e Value will b e pr ojec ted b ehind the sur face. Scale F actor sets the length sc ale fac tor for pr ojec tion. After subtr acting off the Referenc e Value , ANSY S Fluen t mul- tiplies the r esulting solution v alue b y the Scale F actor to form a length. Projec tion D ir. sets the dir ection in which pr ofiles ar e pr ojec ted. In 2D , for e xample , a contour plot of pr essur e on the entire domain c an b e pr ojec ted in the direction t o form a c arpet plot , or a c ontour plot of velocity on 3663Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Graphics and A nima tions Task P agea sequenc e of -coordina te slic e lines c an b e pr ojec ted in the direction t o form a ser ies of v elocity profiles . 47.19.2. Vector Options D ialo g Box The Vector Options dialo g box allo ws you t o set additional par amet ers f or v ector displa ys. It is op ened from the Vectors D ialog Box (p.3954 ). See Vector P lot Options (p.2796 ) for details ab out the it ems b elow. Controls In P lane toggles the displa y of v ector comp onen ts in the plane of the sur face selec ted f or displa y.This f eature is useful f or visualizing c omp onen ts tha t are nor mal t o the flo w. See Drawing Vectors in the P lane of the Surface (p.2797 ) for details . Fixed L ength enables the displa y of v ectors tha t are all the same length. See Displa ying F ixed-L ength Vectors (p.2798 ) for details . X,Y, Z C omp onen t toggle the displa y of the C artesian c omp onen ts of the v ectors. See Displa ying Vector C omp onen ts (p.2798 ) for details . Scale H ead controls the siz e of the ar rowhead on v ector st yles tha t include heads . Color specifies a single c olor f or the displa y of all v ectors. See Displa ying Vectors U sing a S ingle C olor (p.2799 ) for details . 47.19.3. Custom Vectors D ialo g Box The Custom Vectors dialo g box allo ws you t o define cust om v ectors based on e xisting quan tities . Any vectors tha t you define will b e added t o the Vectors of list in the Vectors D ialog Box (p.3954 ).To open the Custom Vectors dialo g box, click Custom Vectors... in the Vectors dialo g box. See Creating and M anaging C ustom Vectors (p.2799 ) for details ab out cust om v ectors. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3664Task P age R eference GuideControls Vector N ame specifies the name of the v ector y ou ar e defining . Should y ou decide t o change the name af ter you ha ve defined the v ector, you c an do so in the Vector D efinitions D ialog Box (p.3665 ), which y ou c an op en b y click ing on the Manage ... butt on. X,Y, Z C omp onen t specify the , , and comp onen ts of the v ector. Each dr op-do wn list c ontains the a vailable field func tions . Define creates the v ector and adds it t o the Vectors of list in the Vectors D ialog Box (p.3954 ). Manage ... opens the Vector D efinitions D ialog Box (p.3665 ), which enables y ou t o check, rename , save, load , and delet e cust om v ectors. 47.19.4. Vector D efinitions D ialo g Box The Vector D efinitions dialo g box allo ws you t o check, rename , save, load , and delet e cust om v ectors that you defined in the Custom Vectors D ialog Box (p.3664 ). See Creating and M anaging C ustom Vec- tors (p.2799 ) for details ab out the it ems b elow. 3665Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Graphics and A nima tions Task P ageControls X,Y, Z C omp onen t displa y the , , and comp onen ts of the v ector. Vectors contains a selec table list of cust om v ectors.When y ou selec t a v ector, its c omp onen ts will app ear in the X,Y, and Z Comp onen t fields , and its name will app ear in the Name field . Name displa ys the name of the cur rently selec ted v ector.You c an en ter a new name in this b ox if y ou w ant to rename the v ector. Rename changes the name of the selec ted func tion t o the name sp ecified in the Name field . Delet e delet es the selec ted v ector. Save... opens The S elec t File D ialog Box (p.569), in which y ou c an sp ecify a file in which t o sa ve all of the cust om vectors in the Vectors list. Load ... opens the Selec t File dialo g box, in which y ou c an sp ecify a file fr om which t o read cust om v ectors (a file that you sa ved using the Save... butt on ab ove). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3666Task P age R eference Guide47.19.5. Path S tyle A ttribut es D ialo g Box To mo dify the line width, cylinder r adius or mar ker siz e, use the Path S tyle A ttribut es dialo g box.You can op en this dialo g box by click ing the Attribut es... butt on in the Pathlines D ialog Box (p.3891 ). See Controlling the P athline S tyle (p.2805 ) for details ab out the it ems b elow. Controls Line Width/M arker S ize/W idth/ determines the thick ness of the pa thlines . Diamet er specifies the diamet er of the spher e.This par amet er app ears only when spher e is selec ted under Style in the Pathlines dialo g box. Spacing F actor controls the spacing of ar rows when y ou use the line-ar rows style. Scale controls the siz e of the ar row heads when y ou use the line-ar rows style. Detail specifies the detail applied t o the gr aphic al render ing of the spher es.This par amet er app ears only when spher e is selec ted under Style in the Pathlines dialo g box. 47.19.6. Ribbon A ttribut es D ialo g Box To mo dify the r ibbon width and set the sc alar field b y which t o twist the r ibbon, use the Ribbon A t- tribut es dialo g box.You c an op en this dialo g box by click ing the Attribut es... butt on in the Pathlines Dialog Box (p.3891 ) when the selec ted Style is ribbon. See Controlling the P athline S tyle (p.2805 ) for details ab out the it ems b elow. 3667Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Graphics and A nima tions Task P ageControls Width determines the thick ness of the r ibbon. Twist Sc ale sets the amoun t of t wist f or a giv en field .To magnify the t wist f or a field with v ery little change , incr ease this fac tor; to displa y less t wist f or a field with dr ama tic changes , decr ease this fac tor. Twist B y contains a dr op-do wn list fr om which y ou c an selec t a sc alar field on which pa thline t wisting is based . Min/M ax displa ys the minimum/maximum v alue of the sc alar field selec ted in Twist B y. 47.19.7. Particle F ilter A ttribut es The Particle F ilter A ttribut es dialo g box allo ws you t o sp ecify ho w you w ould lik e to filt er the par ticles being displa yed. See Particle F iltering (p.2038 ) for details ab out the it ems b elow. Controls Options contains the filt ering options . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3668Task P age R eference GuideInside enables the filt ering of par ticles with v alues b etween Filter-M in and Filter-M ax. Outside enables the filt ering of par ticles with v alues less than Filter-M in or gr eater than Filter-M ax. Filter b y contains a list fr om which y ou c an selec t an y field v ariable , except f or Custom F ield F unc tions ..., to be used as a filt er variable . Min/M ax displa ys the minimum and maximum v alues of the selec ted field v ariable .The r eal numb er field v alues are not editable; the y are pur ely inf ormational. Filter-M in/F ilter-M ax defines the minimum/maximum filt er thr eshold . 47.19.8. Rep orting Variables D ialo g Box The Rep orting Variables dialo g box allo ws you t o control the par ticle v ariables tha t you include in your r eporting . See Step-b y-Step R eporting of Trajec tories (p.2046 ) for details ab out the it ems b elow. Controls Variables in Rep ort contains all v ariables cur rently in the r eport. Remo ve remo ves the selec ted v ariable fr om the r eport. Default Variables restores the default list. 3669Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Graphics and A nima tions Task P ageAvailable P article Variables contains the par ticle v ariables tha t are available f or y ou t o selec t. Add Variables takes the selec ted v ariable fr om the Available P article Variables list and adds it t o the Variables in Rep ort list. Add C olor B y adds the Color b y variable t o the Variables in Rep ort list. 47.19.9. Track S tyle A ttribut es D ialo g Box To mo dify the line width, cylinder r adius or mar ker siz e, use the Track S tyle A ttribut es dialo g box. You c an op en this dialo g box by click ing the Attribut es... butt on in the Particle Tracks D ialog Box (p.3881 ). See Controlling the P article Tracking S tyle (p.2031 ) for details ab out the it ems b elow. Controls Line Width/M arker S ize/W idth determines the thick ness of the par ticle tr acks . Spacing F actor controls the spacing of ar rows when y ou use the line-ar rows style. Scale controls the siz e of the ar row heads when y ou use the line-ar rows style. 47.19.10. Particle S pher e Style A ttribut es D ialo g Box To mo dify the a ttribut es of the par ticle spher e, use the Particle S pher e Style A ttribut es dialo g box. Selec t spher e from the Track S tyle drop-do wn list and click the Attribut es... butt on in the Particle Tracks D ialog Box (p.3881 ) to op en the Particle S pher e Style A ttribut es dialo g box. See Controlling the P article Tracking S tyle (p.2031 ) for details ab out the it ems b elow. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3670Task P age R eference GuideControls Options allows you t o cho ose ho w you w ould lik e to sp ecify the par ticle diamet er. Constan t allows you t o sp ecify the diamet er as a c onstan t value . Variable allows you t o selec t a par ticle v ariable t o estima te the siz e of the spher es. Auto Range when disabled clips the displa yed par ticles t o the v alues giv en in Min and Max. Diamet er specifies the diamet er of the spher e. Scale allows you t o sc ale the spher es b y the fac tor en tered in this field . Detail specifies the detail applied t o the gr aphic al render ing of the spher es. Size by contains a list of v ariables b y which y ou c an estima te the siz e of y our par ticle .This list is selec table only when y ou ar e using the Variable option. Min/M ax defines the minimum and maximum v alues of the selec ted field v ariable t o displa y. 47.19.11. Particle Vector S tyle A ttribut es D ialo g Box To mo dify the a ttribut es of the v ector st yles , use the Particle Vector S tyle A ttribut es dialo g box. See Controlling the Vector S tyle of P article Tracks (p.2033 ) for details ab out the it ems b elow. 3671Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Graphics and A nima tions Task P ageControls Options allows you t o cho ose ho w you w ould lik e to sp ecify the par ticle diamet er. Constan t Length allows you t o sp ecify the v ector length as a c onstan t value . Variable L ength results in a v ector length tha t is based on the v ariable selec ted under Length b y. Constan t Color when enabled allo ws you t o selec t a v ector color fr om the Color drop-do wn list. Other wise , the v ector is color ed based on the v ariable selec ted in the Particle Tracks dialo g box (seen in the Mesh C olors dialo g box when Draw M esh is enabled). Length specifies the length of the v ector. Scale allows you t o sc ale the v ectors b y the fac tor en tered in this field . Length t o Head R atio is the r atio of v ector length t o vector head siz e. Vectors of contains the par ticle v ector v ariable t o displa y. Length b y is used t o estima te the length of the v ector when the Variable L ength option is enabled . 47.19.12. Sweep S urface Dialo g Box The Sweep S urface dialo g box controls the displa y and anima tion of mesh, contour, and v ector plots gener ated on a sw eep sur face. See Displa ying R esults on a S weep Sur face (p.2813 ) for details ab out the items b elow. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3672Task P age R eference GuideControls Sweep A xis specifies the ( X,Y,Z) vector represen ting the axis along which the sur face should b e sw ept. Displa y Type specifies the t ype of displa y to be sw ept thr ough the domain ( Mesh,Contours , or Vectors). Properties ... opens the Contours D ialog Box (p.3790 ) if Contours is the selec ted Displa y Type, or the Vectors D ialog Box (p.3954 ) if Vectors is the selec ted Displa y Type. (This butt on is not a vailable if Mesh is the selec ted Displa y Type.) Anima tion contains c ontrols f or anima ting the sw eep-sur face displa y. Initial Value , Final Value specify the initial and final p ositions f or the anima tion. Frames specifies the numb er of fr ames in the anima tion. Min Value , Max Value show the minimum and maximum e xtents of the domain along the sp ecified Sweep A xis.These v alues are up dated when y ou click Comput e. Value shows the cur rent position a t which the r equest ed displa y is plott ed.You c an change the v alue b y mo ving the slide bar b elow it, or b y en tering a new v alue and pr essing the key. Create... opens the Create Sur face Dialog Box (p.3674 ), wher e you c an cr eate a sur face from the cur rently-displa yed sweep sur face. 3673Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Graphics and A nima tions Task P ageAnima te anima tes the displa y, sweeping the r equest ed displa y thr ough the domain along the sp ecified axis . Comput e updates the Min Value and Max Value to reflec t the minimum and maximum e xtents of the domain along the sp ecified Sweep A xis. 47.19.13. Create Surface Dialo g Box The Create Surface dialo g box allo ws you t o sa ve a sw eep sur face for la ter use .You c an op en it b y click ing Create... in the Sweep Sur face Dialog Box (p.3672 ). See Displa ying R esults on a S weep Sur- face (p.2813 ) for details ab out the it ems b elow. Controls Surface Name specifies a name f or the sur face to be created. 47.19.14. Anima te Dialo g Box The Anima te dialo g box allo ws you t o sp ecify k ey frames tha t define the basic mo vemen t of an anim- ated sequenc e, and then pla y back the anima tion. ANSY S Fluen t interpolates b etween y our sp ecified key frames . See Anima ting G raphics (p.2857 ) for details ab out the it ems b elow. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3674Task P age R eference GuideControls Playback contains the c ontrols tha t you use t o pla y back the anima tion. See Playing an A nima tion (p.2859 ) for details . Playback M ode contains a dr op-do wn list of pla yback options . Play Onc e sets the option t o pla y back fr ames fr om Start Frame to End F rame onc e. Auto Rep eat sets the option t o continually pla y back fr ames fr om Start Frame to End F rame . Auto Re verse sets the option t o continually pla y back the images while r eversing pla yback dir ection af ter each set. Start Frame , End F rame set the fr ames a t which the anima tion should b egin and end . By changing these numb ers y ou c an view a subset of the fr ames . Incr emen t sets the numb er of fr ames t o incr emen t the fr ame-c oun ter b y when y ou use the fast-f orward or fast- reverse butt ons. Frame shows the numb er of the fr ame tha t is cur rently displa yed, as w ell as its r elative position in the en tire anima tion. If you slide the bar t o a diff erent location, the fr ame c orresponding t o the new fr ame numb er will b e displa yed in the gr aphics windo w. (Tape Player Butt ons) allow you t o pla y the anima tion f orward and back ward, fast-r everse and fast-f orward the anima tion, and st op it. The butt ons func tion in a w ay similar t o those on a standar d video c assett e pla yer. Key Frames contains the c ontrols tha t you use t o define the k ey frames f or the anima tion. See Creating an A nima- tion (p.2858 ) for details . Frame sets the numb er to be assigned t o the ne xt key frame added t o the list of Keys. Keys contains a list of the k ey frames tha t ha ve been defined . If you selec t a k ey frame in this list , the asso- ciated sc ene will b e displa yed in the gr aphics windo w. Add creates a k ey frame with the numb er sho wn in Frame for the sc ene cur rently displa yed in the graphics windo w. Imp ortant Be sur e to change the fr ame numb er b efore you add the new k ey frame so tha t you will not o verwrite the last k ey frame tha t you cr eated. 3675Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Graphics and A nima tions Task P ageDelet e delet es the k ey frame tha t is selec ted in the Keys list. Delet e All delet es all k ey frames in the Keys list. Write/Rec ord Format specifies Key Frames ,Picture Files,MPEG , or Video (not a vailable on Windo ws) as the f ormat in which to sa ve the anima tion. See Saving an A nima tion (p.2861 ) for details ab out these options . Picture Options ... opens the Save Picture Dialog Box (p.3676 ), in which y ou c an sp ecify par amet ers f or sa ving the anima tion to pic ture files .This butt on is a vailable only when Picture Files is selec ted as the Write/Rec ord Format. Write... opens The S elec t File D ialog Box (p.569), in which y ou c an sp ecify a name f or the anima tion file and sa ve it. Read ... opens the Selec t File dialo g box, in which y ou c an sp ecify the name of the anima tion file t o be read. Note that the cur rent case and da ta should c ontain the sur faces and an y other inf ormation tha t the k ey frame descr iption r efers t o. See Reading an A nima tion F ile (p.2862 ). 47.19.15. Save Picture Dialo g Box The Save Picture dialo g box allo ws you t o set sa ve pic ture par amet ers and sa ve pic ture files of graphics windo ws. See Saving P icture Files (p.645) for details on the use of this dialo g box. Controls Format allows you t o selec t the f ormat of pic ture files . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3676Task P age R eference GuideEPS (Enc apsula ted P ostScr ipt) output is the same as P ostScr ipt output , with the addition of A dob e Docu- men t Structuring C onventions (v2) sta temen ts. Currently, no pr eview bitmap is included in EPS output. Often, programs tha t imp ort EPS files use the pr eview bitmap t o displa y on-scr een, although the ac- tual v ector P ostScr ipt inf ormation is used f or pr inting (on a P ostScr ipt de vice).You c an sa ve EPS files in raster or v ector format. JPEG is a c ommon r aster file f ormat. PPM output is a c ommon r aster file f ormat. PostScr ipt is a c ommon v ector file f ormat.You c an also cho ose t o sa ve a P ostScr ipt file in r aster format. TIFF is a c ommon r aster file f ormat. PNG is a c ommon r aster file f ormat. HSF is HOOPS Visualiz e Stream F ormat, a highly-c ompr essible and str eamable 2D/3D file f ormat. AVZ is the fr ee ANSY S Viewer Format, which is a 3D file f ormat allo wing y ou t o visualiz e, shar e, collab orate, and in teractively manipula te the displa yed objec t. For additional inf ormation on the ANSY S Viewer, refer to ANSY S Viewer U ser's G uide . VRML is a gr aphics in terchange f ormat tha t allo ws export of 3D geometr ical en tities tha t you c an displa y in the ANSY S Fluen t graphics windo w.This f ormat can c ommonly b e used b y VR sy stems and in par tic- ular the 3D geometr y can b e view ed and manipula ted in a w eb-br owser gr aphics windo w. Imp ortant Non-geometr ic en tities such as t ext, titles , color bars , and or ientation axis ar e not exported. In addition, most displa y or visibilit y char acteristics set in ANSY S Fluen t, such as ligh ting , shading metho d, transpar ency, face and edge visibilit y, and out er face culling , are not e xplicitly e xported but ar e controlled b y the sof tware used t o view the VRML file . Windo w D ump (Linux sy stems only) selec ts a windo w dump op eration f or gener ating the pic ture.With this f ormat, you will need t o sp ecify the appr opriate Windo w D ump C ommand . Color ing (all f ormats except Windo w D ump ) specifies the c olor mo de f or the pic ture file . Color specifies a c olor-sc ale c opy. 3677Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Graphics and A nima tions Task P ageGray Sc ale specifies a gr ay-sc ale c opy. Mono chrome specifies a black-and-whit e copy. Imp ortant Most mono chrome P ostScr ipt de vices will r ender Color images in shades of gr ay, but to ensur e tha t the c olor r amp is r ender ed as a linear ly-incr easing gr ay ramp , you should selec t Gray Sc ale. File Type specifies the t ype of pic ture file t o be sa ved. See Choosing the F ile Type (p.649) for details . Raster specifies a r aster type pic ture.The supp orted r aster formats ar e EPS ,JPEG ,PPM ,PostScr ipt,TIFF , and PNG . Vector specifies a v ector type pic ture.The supp orted v ector formats ar e EPS ,PostScr ipt, and VRML . Resolution specifies the r esolution or the siz e (in pix els) of the pic ture. Use Windo w Resolution uses the r esolution of the cur rent graphics windo w when the image is sa ved. DPI specifies the r esolution of EPS and PostScr ipt files in dots p er inch (DPI). The default v alue f or DPI is set t o 75. Width specifies the width of the r aster pic ture image . Heigh t specifies the heigh t of the r aster pic ture image . The default v alue f or Width and Height is set t o zero, so that the default pic ture is gener ated at the same r esolution as the ac tive gr aphics windo w. Options contains additional options f or all pic ture formats except Windo w D ump . Landsc ape Or ientation specifies the or ientation of the pic ture. If this option is enabled , the pic ture is made in landsc ape mode; other wise , it is made in p ortrait mo de. White Back ground controls the f oreground/back ground c olor . If this option is enabled , the f oreground and back ground colors of gr aphics windo ws being sa ved as pic tures will b e sw app ed. Hence, it allo ws you t o sa ve pictures with a whit e back ground and a black f oreground , while the gr aphics windo ws are displa yed with a black back ground and whit e foreground . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3678Task P age R eference GuideWindo w D ump C ommand (Linux sy stems only) sp ecifies the c ommand t o be used t o sa ve the pic ture file , when y ou selec t the Windo w D ump format. See Windo w D umps (Linux S ystems Only) (p.650) for details . Save... opens The S elec t File D ialog Box (p.569), in which y ou c an sp ecify a name f or the pic ture file t o be sa ved and then sa ve the file .The r esulting file will c ontain a pic ture of the ac tive gr aphics windo w. Apply saves the cur rent settings . ANSY S Fluen t will use these settings when mak ing subsequen t pic tures. Preview applies the cur rent settings t o the ac tive gr aphics windo w so tha t you c an in vestiga te the eff ects of dif- ferent options in teractively b efore sa ving the final pic ture. 47.19.16. Playback D ialo g Box The Playback dialo g box allo ws you t o pla y back an anima tion sequenc e. See Playing an A nima tion Sequenc e (p.2673 ) for details ab out the it ems b elow. Controls Playback contains the c ontrols tha t you use t o pla y back the selec ted anima tion sequenc e. Playback M ode contains a dr op-do wn list of pla yback options . Play Onc e sets the option t o pla y back fr ames fr om Start Frame to End F rame onc e. 3679Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Graphics and A nima tions Task P ageAuto Rep eat sets the option t o continually pla y back fr ames fr om Start Frame to End F rame . Auto Re verse sets the option t o continually pla y back the images while r eversing pla yback dir ection af ter each set. Use S tored View disabling allo ws you t o mo dify the view dur ing anima tion pla yback ( In M emor y and HSF F ile 3D anima tions only). Start Frame , End F rame set the fr ames a t which the anima tion should b egin and end . By changing these numb ers y ou c an view a subset of the fr ames . Incr emen t sets the numb er of fr ames t o incr emen t the fr ame-c oun ter b y when y ou use the fast-f orward or fast- reverse butt ons. Frame shows the numb er of the fr ame tha t is cur rently displa yed, as w ell as its r elative position in the en tire anima tion. If you slide the bar t o a diff erent location, the fr ame c orresponding t o the new fr ame numb er will b e displa yed in the gr aphics windo w. (Tape Player Butt ons) allow you t o pla y the anima tion f orward and back ward, fast-r everse and fast-f orward the anima tion, and st op it. The butt ons func tion in a w ay similar t o those on a standar d video c assett e pla yer. Repla y Speed controls the pla yback sp eed f or the anima tion. Move the Repla y Speed slider bar t o the lef t to reduc e the pla yback sp eed (and t o the r ight to incr ease it). Anima tion S equenc es contains the c ontrols tha t you use t o define the sequenc e to be pla yed back. Sequenc es contains a list of the anima tion sequenc es tha t ha ve been defined . Delet e delet es the anima tion sequenc e tha t is selec ted in the Sequenc es list. Delet e All delet es all anima tion sequenc es in the Sequenc es list. Write/Rec ord Format specifies Anima tion F rames ,Picture Files, or MPEG as the f ormat in which t o sa ve the anima tion. See Saving an A nima tion S equenc e (p.2675 ) for details ab out these options . Picture Options ... opens the Save Picture Dialog Box (p.3676 ), in which y ou c an sp ecify par amet ers f or sa ving the anima tion to pic ture files .This butt on is a vailable only when Picture Files is selec ted as the Write/Rec ord Format. Write saves the sp ecified file(s) in the cur rent working dir ectory. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3680Task P age R eference GuideRead ... opens The S elec t File D ialog Box (p.569), in which y ou c an sp ecify the name of the solution anima tion file to be read. See Reading an A nima tion S equenc e (p.2677 ) for details . 47.19.17. Displa y Options D ialo g Box The Displa y Options dialo g box pr ovides an in teractive mechanism f or setting a ttribut es or options that control ho w and wher e a sc ene is r ender ed. Controls Render ing allows you t o mo dify char acteristics of the displa y tha t are related t o the w ay in which sc enes ar e render ed. See Modifying the R ender ing Options (p.2831 ) for details ab out these it ems . Line Width controls the thick ness of lines .The default is 1. Point Symb ol sets the symb ol used f or no des and da ta p oints. Anima tion Option contains a dr op-do wn list of anima tion options: All and Wireframe .Wireframe uses a wir eframe represen tation of all geometr y dur ing mouse manipula tion This option is tur ned on b y default. You should tur n it off only if y our c omput er has a gr aphics acc elerator; other wise the mouse manipula tion may be very slo w. 3681Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Graphics and A nima tions Task P ageDouble Buff ering turns double buff ering on or off , if it is supp orted b y the dr iver. Double buff ering dr ama tically r educ es screen flick er dur ing gr aphics up dates. Note tha t if y our displa y har dware do es not supp ort double buff ering and y ou tur n this option on, double buff ering will b e done in sof tware. Software double buff ering uses e xtra memor y. Out er F ace Culling allows you t o tur n off the displa y of out er fac es in w all z ones .Out er F ace Culling is useful f or displa ying both sides of a slit w all. By default , when y ou displa y a slit w all, one side will “bleed ” through t o the other .When y ou tur n on the Out er F ace Culling option, the displa y of a slit w all will sho w each side distinc tly as y ou r otate the displa y.This option c an also b e useful f or displa ying t wo-sided w alls (w alls with fluid or solid c ells on b oth sides). Hidden S urface Remo val turns hidden sur face remo val on or off . If you do not use hidden sur face remo val, ANSY S Fluen t will not tr y to det ermine which sur faces in the displa y are behind others; it will displa y all of them, and a clutt ered displa y will r esult. You should tur n this option off if y ou ar e working with a 2D pr oblem or with geometr ies tha t do not o verlap. Remo val M etho d chooses the metho d to be used f or hidden sur face remo val.These options v ary in sp eed and qualit y, dep ending on the de vice you ar e using .The choic es ar e list ed b elow. Hardware Z-buff er is the fast est metho d if y our har dware supp orts it. The accur acy and sp eed of this metho d is hardware dep enden t. Painters will sho w fewer edge-aliasing eff ects than har dware-z-buff er.This metho d is of ten used inst ead of sof tware-z-buff er when memor y is limit ed. Software Z-buff er is the fast est of the accur ate sof tware metho ds a vailable (esp ecially f or comple x scenes), but it is memor y intensiv e. Z-sor t only is a fast sof tware metho d, but it is not as accur ate as sof tware-z-buff er. Timeout in sec onds specifies the v alue f or the timeout. Graphics Windo w allows you t o op en and close gr aphics windo ws. See Opening M ultiple G raphics Windo ws (p.2818 ) for details . Active Windo w indic ates the gr aphics windo w to be op ened , closed , or set ac tive. (A gr aphics windo w’s ID is displa yed in its title .) Open/C lose opens or closes the windo w with the ID sho wn in the Active Windo w box. If the indic ated windo w is op en, the Close butt on will app ear, and if the indic ated windo w is not op en, the Open butt on will app ear. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3682Task P age R eference GuideSet sets the windo w with the ID sho wn in the Active Windo w box to be the ac tive gr aphics windo w. See Setting the A ctive Windo w (p.2819 ) for details . Ligh ting A ttribut es controls ligh ting a ttribut es for all ligh ts in the ac tive gr aphics windo w. See Adding Ligh ts (p.2829 ) for details . Ligh ts On turns all ligh ts in the ac tive gr aphics windo w on or off . Ligh ting specifies the metho d to be used in ligh ting in terpolation: Flat,Gour aud , or Phong . (Flat is the most basic metho d: ther e is no in terpolation within the individual p olygonal fac ets.Gour aud and Phong have smo other gr adations of c olor b ecause the y interpolate on each fac et.) Layout controls the displa y of c aptions , axes and the c olor map in the gr aphics displa y windo w. See Changing the L egend D ispla y (p.2819 ) for details . Logo allows you t o hide or displa y the ANSY S logo. Color contains a dr op-do wn list of c olors tha t can b e used f or the lo go.The choic es ar e White or Black . Color map enables/disables the displa y of the c olor sc ale. Color map A lignmen t allows you t o adjust the alignmen t of c olor map in the gr aphics displa y. Selec t the side ( Top,Bottom, Left, and Right) from the dr op-do wn list , wher e you w ant to align the c olor map . Apply applies the sp ecified a ttribut es and r e-renders the sc ene in the ac tive gr aphics windo w with the new a t- tribut es.To see the eff ect of the new a ttribut es on other gr aphics windo ws, you must r edispla y them. Info prints out inf ormation ab out y our gr aphics dr iver in the c onsole . Ligh ts... opens the Ligh ts D ialog Box (p.3696 ), which allo ws you t o create, delet e, and mo dify dir ectional ligh t sour ces. 47.19.18. Scene D escr iption D ialo g Box The Scene D escr iption dialo g box allo ws you t o tur n overlays on and off , selec t geometr ic objec ts in the displa y for mo dific ation or deletion, and op en dialo g boxes tha t control various char acteristics of the selec ted objec t(s). (Note tha t you c annot use the Scene D escr iption dialo g box to control X Y plot and hist ogram displa ys.) See Advanced Sc ene C omp osition (p.2848 ) for details ab out the it ems b elow. 3683Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Graphics and A nima tions Task P ageControls Names contains a list of the geometr ic objec ts tha t cur rently e xist in the sc ene (including those tha t are pr esen tly invisible). You c an sp ecify the objec t or objec ts to be manipula ted b y selec ting names in this list. If you selec t mor e than one objec t at a time , any op eration (tr ansf ormation, color sp ecific ation, and so on) will apply t o all the selec ted objec ts.You c an also selec t objec ts by click ing on them in the gr aphics displa y using the mouse pr obe butt on, which is , by default , the r ight mouse butt on. (See Controlling the M ouse Button F unctions (p.2833 ) for inf ormation ab out mouse butt on func tions .) To deselec t a selec ted objec t, simply click its name in the Names list. See Selec ting the O bjec t(s) t o be Manipula ted (p.2849 ) for details . Geometr y Attribut es contains inf ormation ab out the t ype of the selec ted geometr ic objec t and push butt ons tha t op en dialo g boxes for mo difying the objec t. Type reports the t ype of the selec ted objec t. Possible t ypes include mesh ,surface ,contour ,vector , and Group .This inf ormation is esp ecially helpful when y ou need t o distinguish t wo or mor e objec ts with the same name .When mor e than one objec t is selec ted, the t ype displa yed is Group . Displa y... opens the Displa y Properties D ialog Box (p.3685 ), which allo ws you t o change the c olor , visibilit y, and other pr operties f or the selec ted objec t. Transf orm... opens the Transf ormations D ialog Box (p.3687 ), which allo ws you t o transla te, rotate, and sc ale the selec ted objec t. Iso-V alue ... opens the Iso-V alue D ialog Box (p.3688 ), which allo ws you t o change the iso value of an isosur face.This push butt on is a vailable only if the geometr ic objec t selec ted in the Names list is an isosur face or an objec t on an isosur face (contour on an isosur face, for e xample); other wise it is gr ayed out. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3684Task P age R eference GuidePathlines ... opens the Pathline A ttribut es D ialog Box (p.3689 ), which allo ws you t o set the maximum numb er of steps f or the selec ted pa thlines . Scene C omp osition contains c ontrols f or enabling o verlays and b ounding fr ames . Overlays activates the sup erimp osition of a new geometr y on to a cur rently displa yed geometr y. See Advanced Graphics O verlays (p.2817 ) for details . Draw Frame activates the displa y of a b ounding fr ame in the gr aphics displa y. See Adding a B ounding F rame (p.2855 ) for details . Frame Options ... opens the Bounding F rame D ialog Box (p.3689 ), in which y ou c an define pr operties of the b ounding fr ame . See Adding a B ounding F rame (p.2855 ) for details . Delet e Geometr y delet es the geometr ic objec t tha t is cur rently selec ted in the Names list. The abilit y to delet e individual objec ts is esp ecially useful if y ou ha ve overlays on and y ou gener ate an unw anted objec t (for e xample , if you gener ate contours of the wr ong v ariable). You c an simply delet e the unw anted objec t and c ontinue your sc ene c omp osition, inst ead of star ting o ver fr om the b eginning . Apply saves the sta tus of Overlays and Draw Frame .When y ou tur n Overlays or Draw Frame on or off , you must click the Apply butt on t o see the eff ect of the change on subsequen t displa y op erations . 47.19.19. Displa y Properties D ialo g Box To mo dify the c olor , visibilit y, and other displa y pr operties f or individual geometr ic objec ts in the graphics displa y, use the Displa y Properties dialo g box.You c an op en this dialo g box by click ing the Displa y... push butt on in the Scene D escr iption D ialog Box (p.3683 ). See Changing an O bjec t’s Displa y Properties (p.2850 ) for details ab out the it ems b elow. 3685Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Graphics and A nima tions Task P ageControls Geometr y Name displa ys the name of the objec t you selec ted f or mo dific ation in the Scene D escr iption D ialog Box (p.3683 ). Visibilit y contains check butt ons tha t control options r elated t o the visibilit y of the selec ted objec t. See Controlling Visibilit y (p.2851 ) for details . Visible toggles the visibilit y of the selec ted objec t. If it is tur ned on, the objec t will b e visible in the displa y, and if it is tur ned off , the objec t will b e invisible . Ligh ting turns the eff ect of ligh ting f or the selec ted objec t on or off .You c an cho ose t o ha ve ligh ting aff ect only c ertain objec ts inst ead of all of them. Note tha t if Ligh ting is tur ned on f or an objec t such as a contour or v ector plot , the c olors in the plot will not b e exactly the same as those in the c olor map a t the lef t of the displa y. Faces toggles the filled displa y of fac es for the selec ted mesh or sur face objec t.Turning Faces on has the same eff ect as tur ning on the displa y of fac es in the Mesh D ispla y Dialog Box (p.3239 ). Out er F aces toggles the displa y of out er fac es. Edges toggles the displa y of in terior and e xterior edges of the geometr ic objec t. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3686Task P age R eference GuidePerimet er E dges toggles the displa y of the outline of the geometr ic objec t. (This option has no eff ect on the displa y of meshes .) Feature Edges toggles the displa y of f eature lines (if an y) of the geometr ic objec t. Lines toggles the displa y of the lines (if an y) in the geometr ic objec t. Nodes toggles the displa y of the no des (if an y) in the geometr ic objec t. Colors contains c ontrols f or setting fac e, edge , line , and no de c olors , and tr anspar ency for fac es. See Controlling Objec t Color and Transpar ency (p.2851 ) for details . Color specifies the fac e, edge , line , or no de c olor f or mo dific ation. When y ou tur n on this butt on, the c olor scales b elow will sho w the cur rent color sp ecific ation, which y ou c an mo dify b y mo ving the sliders on the c olor sc ales . Red , Green, Blue are color sc ales with which y ou c an sp ecify the R GB c omp onen ts of the fac e, edge or line c olor . Transpar enc y sets the r elative transpar ency of the selec ted objec t. An objec t with a tr anspar ency of 0 is opaque , and an objec t with a tr anspar ency of 100 is tr anspar ent. 47.19.20. Transf ormations D ialo g Box You c an use the Transf ormations dialo g box to transla te, rotate, or sc ale individual objec ts in the graphics displa y.To op en this dialo g box, click the Transf orm... push butt on in the Scene D escr iption Dialog Box (p.3683 ). See Transf orming G eometr ic O bjec ts in a Sc ene (p.2852 ) for details ab out the it ems below. 3687Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Graphics and A nima tions Task P ageControls Geometr y Name displa ys the name of the objec t you selec ted f or mo dific ation in the Scene D escr iption D ialog Box (p.3683 ). Meridional (3D only) enables the displa y of the mer idional view .This option is esp ecially useful in turb omachiner y applic ations . Transla te contains X,Y, and Z real numb er fields in which y ou c an en ter the distanc e by which t o transla te the se- lected objec t in each dir ection. Rota te by contains X,Y,and Z integer numb er fields in which y ou c an en ter the numb er of degr ees b y which t o rotate the selec ted objec t ab out each axis . Rota te ab out specifies the p oint ab out which t o rotate the objec t. Scale contains X,Y, and Z real numb er fields in which y ou c an en ter the amoun t by which t o sc ale the selec ted objec t in each dir ection. To avoid dist ortion of the objec t’s shap e, be sur e to sp ecify the same v alue f or all thr ee en tries. 47.19.21. Iso-V alue D ialo g Box The Iso-V alue dialo g box allo ws you t o change the iso value of an isosur face.The isosur face can b e selec ted dir ectly in the Names list or indir ectly b y selec ting an objec t displa yed on the isosur face. When y ou change the iso value , any contours , vectors, and so on tha t were displa yed on the or iginal isosur face will b e displa yed on the isosur face with the new iso value .To op en this dialo g box, click the Iso-V alue ... push butt on in the Scene D escr iption D ialog Box (p.3683 ). See Modifying I so-V alues (p.2854 ) for details ab out using this dialo g box. Controls Geometr y Name displa ys the name of the geometr ic objec t (isosur face) you selec ted f or mo dific ation in the Scene D escr ip- tion D ialog Box (p.3683 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3688Task P age R eference GuideMin, Max show the minimum and maximum v alues of the isosur face variable . Value sets the new iso value f or isosur faces. After you change the v alue and click Apply , contours , vectors, or pathlines tha t were displa yed on the or iginal isosur face will b e displa yed f or the new iso value .You c an also use the slide bar t o change the Value . 47.19.22. Pathline A ttribut es D ialo g Box The Pathline A ttribut es dialo g box allo ws you t o change the numb er of st eps used in the c omputa tion of pa thlines .This is most useful in cr eating anima tions of pa thlines .To op en this dialo g box, click the Pathlines ... butt on in the Scene D escr iption D ialog Box (p.3683 ). See Modifying P athline A ttribut es (p.2854 ) for details ab out using this dialo g box. Controls Geometr y Name displa ys the name of the geometr ic objec t you selec ted f or mo dific ation in the Scene D escr iption D ialog Box (p.3683 ). Max S teps sets the new maximum numb er of st eps f or pa thline c omputa tion. After you change the v alue and click Apply , the selec ted pa thline will b e recomput ed and r edrawn. 47.19.23. Bounding F rame D ialo g Box The Bounding F rame dialo g box allo ws you t o add a b ounding fr ame with optional measur e mar kings to the displa y of the domain. See Adding a B ounding F rame (p.2855 ) for details ab out the it ems in this dialo g box. 3689Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Graphics and A nima tions Task P ageControls Frame E xtents indic ates the e xtents of the b ounding fr ame . Domain specifies tha t the fr ame should enc ompass the domain e xtents. Displa y specifies tha t the fr ame should enc ompass the p ortion of the domain tha t is sho wn in the displa y. Axes contains c ontrols f or sp ecifying the fr ame b oundar ies and measur emen ts. See Adding a B ounding Frame (p.2855 ) for instr uctions on using these it ems . Displa y updates the ac tive gr aphics windo w with the cur rent frame settings . 47.19.24. Views Dialo g Box With the Views dialo g box, you c an mak e various mo dific ations t o the view displa yed in the ac tive graphics windo w. See Modifying the View (p.2835 ) for details ab out the it ems b elow. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3690Task P age R eference GuideControls Views lists the cur rently defined view s. Clicking on a view name highligh ts tha t name and en ters it in to the Name field . Double-click ing on a view name r estores tha t view in the ac tive gr aphics windo w. Save Name specifies the name t o use when sa ving a view . Actions contains butt ons f or p erforming v arious ac tions r elated t o the Views list and the Save Name . Default restores the “front” view in the ac tive gr aphics windo w. Auto Sc ale modifies the view in the ac tive gr aphics windo w by scaling and c entering the cur rent scene without changing its or ientation. Previous allows you t o retur n to pr evious displa ys. Save stores the view in the ac tive gr aphics windo w with the name in the Save Name box. See Saving Views (p.2843 ) for details . Delet e remo ves the selec ted view name fr om the Views list. Imp ortant Be careful not t o delet e an y of the pr e-defined view s. 3691Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Graphics and A nima tions Task P ageRead ... opens The S elec t File D ialog Box (p.569), in which y ou c an sp ecify the name of a view file t o be read. See Reading View F iles (p.2844 ) for details . Write... opens the Write Views Dialog Box (p.3692 ), in which y ou c an selec t the view s to be sa ved t o a view file . See Saving Views (p.2843 ) for details . Mirror P lanes displa ys a list of all symmetr y planes in the domain. Mirror images ar e dr awn f or all selec ted symmetr y planes . See Mirroring and P eriodic R epeats (p.2844 ) for details . Define P lane ... opens the Mirror P lanes D ialog Box (p.3693 ), in which y ou c an define a mir ror plane f or a non-symmetr ic domain. Periodic Rep eats indic ates the numb er of p eriodic r epetitions t o be displa yed. See Mirroring and P eriodic R epeats (p.2844 ) for details . Define ... opens the Graphics P eriodicit y Dialog Box (p.3693 ), in which y ou c an define p eriodicit y for a p eriodic domain. Camer a... opens the Camer a Paramet ers D ialog Box (p.3695 ). 47.19.25. Write Views Dialo g Box The Write Views dialo g box allo ws you t o sa ve selec ted view s to a view file .To op en it , click Write... in the Views Dialog Box (p.3690 ).This f eature allo ws you t o transf er view s between c ase files . See Saving Views (p.2843 ) for details . Controls Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3692Task P age R eference GuideViews to Write is a selec table list of the defined view s.The selec ted view s will b e sa ved t o a view file when y ou click OK. 47.19.26. Mirror P lanes D ialo g Box The Mirror P lanes dialo g box allo ws you t o define a symmetr y plane f or a non-symmetr ic domain f or use with gr aphics .To op en it , click Define P lane ... in the Views Dialog Box (p.3690 ). See Mirroring f or Graphics (p.2848 ) for details . Controls Plane E qua tion contains inputs f or sp ecifying the equa tion f or the mir ror plane: A X + B Y+ C Z = Distanc e. Mirror P lanes contains a list of all mir ror planes y ou ha ve defined using this dialo g box. (Mirror planes tha t exist in the domain due t o symmetr y will not app ear in this list , sinc e the y cannot b e mo dified .) Add adds the plane defined b y the Plane E qua tion to the Mirror P lanes list. Delet e delet es the plane(s) selec ted in the Mirror P lanes list. 47.19.27. Graphics P eriodicit y Dialo g Box The Graphics P eriodicit y dialo g box allo ws you t o define a p eriodic r epeats, periodic r otation or transla tion f or a non-p eriodic domain f or use with gr aphics .To op en it , click Define ... under Periodic Rep eats in the Views Dialog Box (p.3690 ). See Periodic R epeats for G raphics (p.2846 ) for details . 3693Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Graphics and A nima tions Task P ageControls Cell Z ones contains the list of the z ones in the mesh. You c an selec t one or mor e zones in this list and sp ecify diff erent periodicit y par amet ers f or each z one separ ately. Associated S urfaces contains the list of the sur faces asso ciated with the selec ted c ell z one . Periodic Type specifies Rota tional or Transla tional periodicit y. Angle specifies the angle b y which the domain is r otated t o create the p eriodic r epeat.This it em is a vailable when y ou selec t Rota tional as the Periodic Type. Transla tion specifies the distanc e in the X,Y, and Z directions b y which the domain is tr ansla ted t o create the p eriodic repeat.This it em will app ear when y ou selec t Transla tional as the Periodic Type. Axis D irection specifies the dir ection v ector (X,Y,Z) for the axis of r otation. This it em is a vailable when y ou selec t Rota- tional as the Periodic Type and the domain is thr ee-dimensional. Axis Or igin specifies the or igin of the axis of r otation. This it em is a vailable when y ou selec t Rota tional as the Peri- odic Type. Numb er of Rep eats specifies the numb er of times y ou w ant to repeat the p eriodic domain. Set applies the p eriodicit y you ha ve defined f or the c ase setup . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3694Task P age R eference GuideReset remo ves an y periodicit y you ha ve defined , and r etur ns to the default p eriodicit y for the domain (no periodicit y for a non-p eriodic domain). 47.19.28. Camer a Paramet ers D ialo g Box The Camer a Paramet ers dialo g box allo ws you t o mo dify the “camer a” through which y ou ar e viewing the gr aphics displa y. See Controlling P ersp ective and C amer a Paramet ers (p.2842 ) for details ab out the items b elow. Controls Camer a contains a dr op-do wn list of the par amet ers tha t define the c amer a (Position ,Target,Up Vector, and Field ) and X,Y, and Z fields in which y ou c an define the c oordina tes or field distanc es for the par amet er selec ted in the dr op-do wn list. Figur e 40.43: Camer a Definition (p.2842 ) illustr ates the definition of the camer a by these par amet ers. Projec tion contains a dr op-do wn list tha t allo ws you t o selec t a Persp ective or Ortho graphic view . (Dial and S liders) allow you t o rotate and sc ale the gr aphics displa y.The slider on the sc ale t o the lef t of the dial r otates the displa y ab out the hor izontal axis a t the c enter of the scr een, the slider on the sc ale b elow the dial rotates the displa y ab out the v ertical axis a t the c enter of the scr een, and the dial c ontrols r otation ab out the axis a t the c enter of and p erpendicular t o the scr een. The slider on the sc ale t o the r ight of the dial zooms in or out in the displa y. See Rotating the D ispla y (p.2839 ) and Zooming the D ispla y (p.2840 ) for details . Imp ortant When y ou ar e using the sliders and dial t o manipula te the view , you ma y want to tur n off Wireframe A nima tion in the Displa y Options D ialog Box (p.3681 ), so tha t you c an 3695Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Graphics and A nima tions Task P agewatch the displa y mo ve in teractively while y ou ar e mo ving the slider or the dial indic- ator. 47.19.29. Ligh ts D ialo g Box The Ligh ts dialo g box pr ovides an in teractive mechanism f or placing c olor ed, directional ligh ts in a scene. See Adding Ligh ts (p.2829 ) for details ab out the it ems b elow. Controls Ligh t ID indic ates the ligh t tha t is b eing added , delet ed, or mo dified . By default , ligh t 1 is defined t o be dar k gr ay with a dir ection of (1,1,1). Ligh t On indic ates whether or not the ligh t specified in Ligh t ID is on or off . By tur ning off the Ligh t On option f or a par ticular ligh t, you c an r emo ve this ligh t from the displa y, while still r etaining its definition. To add it to the displa y again, simply tur n on the Ligh t On butt on. Direction allows you t o sp ecify the dir ection of the ligh t (the p osition on the unit spher e from which the ligh t em- anates) b y en tering the X,Y, and Z coordina tes or b y computing the c oordina tes based on the cur rent view in the gr aphics windo w. X,Y,Z specify the dir ection of the ligh t. For e xample , the dir ection (1,1,1) means tha t the r ays from the ligh t will b e par allel t o the v ector fr om (1,1,1) t o the or igin. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3696Task P age R eference GuideUse View Vector updates the X,Y,Z fields with the appr opriate values f or the cur rent view in the ac tive gr aphics windo w, and shines a ligh t in tha t dir ection. Inst ead of en tering the X,Y,Z values f or a ligh t’s dir ection v ector, you c an use y our mouse t o change the view in the gr aphics windo w so tha t your p osition in r eference to the geometr y is the p osition fr om which y ou w ould lik e a ligh t to shine .You c an then click the Use View Vector butt on t o up date the X,Y,Z fields with the appr opriate values f or y our cur rent position and up date the gr aphics displa y with the new ligh t dir ection. This metho d is c onvenien t if y ou k now wher e you w ant a ligh t to be, but y ou ar e not sur e of the e xact dir ection v ector. Color allows you t o sp ecify the ligh t color with sliders .You c an cr eate your desir ed c olor b y incr easing and de- creasing the slider v alues f or the c olors Red ,Green , and Blue .You c an also en ter a descr iptiv e str ing (f or example , lavender) in the Color field . Active Ligh ts shows the p osition and c olor of all defined dir ectional ligh ts, and allo ws you t o change the p osition of a ligh t. All dir ectional ligh ts in ANSY S Fluen t are assumed t o be at infinit y and pass thr ough the unit spher e at the p osition sho wn. All ligh t rays arriving a t the sc ene fr om one ligh t are par allel. The c olor ed mar kers on the sur face of the spher e represen t the c olor and dir ection of these distant ligh ts.These ligh ts point towards the c enter of the spher e (the or igin, which is usually wher e the geometr y is). Ligh ting M etho d specifies the metho d to be used in ligh ting in terpolation: Off,Flat,Gour aud , or Phong . (Flat is the most basic metho d: ther e is no in terpolation within the individual p olygonal fac ets.Gour aud and Phong have smo other gr adations of c olor b ecause the y interpolate on each fac et.) When Off is selec ted, ligh ting eff ects are disabled . Headligh t On enables c onstan t ligh ting eff ects in the dir ection of the view . Reset resets the ligh t definitions t o their last sa ved sta te (the ligh ting tha t was in eff ect the last time y ou op ened the dialo g box or click ed on Apply ). 47.19.30. Color map D ialo g Box The Color map dialo g box allo ws you t o selec t and mo dify e xisting c olor maps . See Selec ting a Color map (p.2825 ) for details . 3697Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Graphics and A nima tions Task P ageControls Show C olor map this option is only visible when acc essed thr ough a gr aphics objec t dialo g box, such as Contours or Vectors. It allo ws you t o tur n the displa y of the c olor map in the gr aphics windo w on/off . Labels allows you t o cust omiz e the displa y of y our c olor map lab els. Show A ll Enable this option if y ou w ant all the lab els t o sho w alongside the c olor map . Disable if y ou w ant to skip some of the lab el displa ys. Skip sets the numb er of lab els t o be sk ipped. Numb er F ormat contains c ontrols f or changing the f ormat of the lab els on the c olor sc ale.These lab els ar e the char- acter str ings used t o define the c olor divisions a t the lef t of the gr aphics windo w. Type sets the f orm of the lab els.You ma y selec t from a dr op-do wn list of options , including the f ollowing: gener al displa ys the r eal v alue with either floa t or e xponen tial f orm based on the siz e of the numb er and the defined Precision . floa t displa ys the r eal v alue with an in tegral and fr actional par t (for e xample , 1.0000), wher e the numb er of digits in the fr actional par t is det ermined b y Precision . exponen tial displa ys the r eal v alue with a man tissa and e xponen t (for e xample , 1.0e-02), wher e the numb er of digits in the fr actional par t of the man tissa is det ermined b y Precision . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3698Task P age R eference GuidePrecision defines the numb er of fr actional digits displa yed in the lab els. Color map contains c ontrols f or the c olor map siz e and sc ale, and f or selec tion of a defined c olor map . Log Sc ale enables the use of a lo garithmic sc ale f or the c olor sc ale (r ather than the default decimal sc ale). See Specifying the C olor map S ize and Sc ale (p.2825 ) for details . Color map S ize specifies the numb er of distinc t colors in the c olor map .You ma y sp ecify fr om 2 t o 100 c olors . Currently D efined contains a dr op-do wn list of all pr e-defined c olor maps and all cust om c olor maps defined b y you. Selec t the c olor map t o be used fr om this list. Edit... opens the Color map E ditor D ialog Box (p.3699 ), in which y ou c an cr eate a cust om c olor map . 47.19.31. Color map E ditor D ialo g Box The Color map E ditor dialo g box allo ws you t o cr eate cust om c olor maps . See Creating a C ustomiz ed Color map (p.2827 ) for details ab out the it ems b elow. Controls 3699Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Graphics and A nima tions Task P age(The D rawing A rea) is used t o interactively mo dify c olor maps .You c an use the notion of anchor p oints to interpolate linear ly between t wo defined anchor p oints.The c olors a t the t op of the dialo g box allo w you t o pr eview the color map tha t is b eing defined .The black bar and whit e squar es b elow the c olors allo w you t o set , delet e, and mo dify anchor p oints. Color specifies c olor c omp onen ts for the cur rently selec ted anchor p oint. Color S pac e gives y ou a choic e of selec ting the c olor sp ecific ation. RGB enables the sp ecific ation of c olors based on their r ed, green, and blue c omp onen ts. HSV enables the sp ecific ation of c olors based on their hue , saturation, and v alue . Red , Green, Blue are sc ales with which y ou c an sp ecify the R GB c omp onen ts of the selec ted anchor c olor .These scales will app ear when RGB is selec ted. Hue , Saturation, Value are sc ales with which y ou c an sp ecify the HSV c omp onen ts of the selec ted anchor c olor .These scales will app ear when HSV is selec ted. Color map lists c olor map names and the name of the c olor map b eing edit ed. Name sets the name of the c olor map b eing edit ed/selec ted.You c an r ename e xisting c olor maps and pr ovide names f or new c olor maps . Currently D efined contains a dr op-do wn list of all pr e-defined c olor maps and all cust om c olor maps defined b y you.You can selec t a c olor map t o be mo dified fr om this list. Color map S ize specifies the numb er of distinc t colors in the c olor map .You ma y sp ecify fr om 2 t o 100 c olors . 47.19.32. Annota te Dialo g Box You c an use the Annota te dialo g box to add t ext with optional a ttachmen t lines t o the gr aphics windo ws, or t o mo dify e xisting t ext. See Adding Text Using the A nnota te Dialog Box (p.2822 ) for details about the it ems b elow. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3700Task P age R eference GuideControls Names contains a selec table list of all annota tion t ext str ings tha t ha ve been defined .You c an cho ose a t ext str ing to be delet ed or edit ed. Delet e Text delet es the t ext str ings selec ted in the Names list fr om the displa y. Annota tion Text contains the annota tion t ext str ing y ou w ant to add , or the annota tion t ext str ing f or the it em selec ted in the Names list. Font Specific ation contains c ontrols f or defining or mo difying the f ont in the annota tion t ext str ing. Name contains a dr op-do wn list of v arious f ont styles . Weigh t contains a dr op-do wn list fr om which y ou c an selec t Medium or Bold. Color contains a dr op-do wn list of c olors tha t can b e used f or the t ext. Slant contains a dr op-do wn list fr om which y ou c an selec t Regular or Italic as the slan t type. Size contains a dr op-do wn list of f ont siz es (in p oints). Add adds the cur rent Annota tion Text to the ac tive gr aphics windo w. A dialo g box will pr ompt y ou t o selec t a scr een lo cation using the mouse-pr obe butt on on y our mouse (see Controlling the M ouse B utton Functions (p.2833 ) for mor e inf ormation on setting the mouse butt ons). 3701Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Graphics and A nima tions Task P ageEdit updates the edit ed t ext in the ac tive gr aphics windo w.This butt on will r eplac e the Add butt on when y ou are editing an e xisting t ext str ing fr om the Names list. Clear remo ves all annota tion t ext and a ttachmen t lines fr om the ac tive gr aphics windo w. 47.20. Plots Task P age The Plots task page allo ws you t o cr eate plots (X Y, hist ograms , profiles , and so on) of y our c omputa- tional r esults . See Displa ying G raphics (p.2775 ) for mor e inf ormation. Controls Plots contains a listing of the v arious plot t ypes a vailable in ANSY S Fluen t. You c an double-click an it em in the Plots list t o op en the c orresponding dialo g box, or y ou c an selec t the it em in the list and click the Set U p... butt on. XY Plot selec ting this it em and click ing the Set U p... butt on op ens the Solution X Y Plot D ialog Box (p.3703 ). Hist ogram selec ting this it em and click ing the Set U p... butt on op ens the Hist ogram D ialog Box (p.3707 ). File selec ting this it em and click ing the Set U p... butt on op ens the File X Y Plot D ialog Box (p.3708 ). Profiles two types of pr ofile plots ar e available: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3702Task P age R eference GuideProfile D ata selec ting this it em and click ing the Set U p... butt on op ens the Plot P rofile D ata D ialog Box (p.3711 ). Interpolated D ata selec ting this it em and click ing the Set U p... butt on op ens the Plot In terpolated D ata D ialog Box (p.3711 ). FFT selec ting this it em and click ing the Set U p... butt on op ens the Fourier Transf orm D ialog Box (p.3712 ). Set U p... displa ys the dialo g box corresponding t o the selec ted it em in the Plots list. For additional inf ormation, see the f ollowing sec tions: 47.20.1. Solution X Y Plot D ialog Box 47.20.2. Hist ogram D ialog Box 47.20.3. File X Y Plot D ialog Box 47.20.4. Plot P rofile D ata D ialog Box 47.20.5. Plot In terpolated D ata D ialog Box 47.20.6. Fourier Transf orm D ialog Box 47.20.7. Plot/M odify Input S ignal D ialog Box 47.20.8. Axes D ialog Box 47.20.9. Curves D ialog Box 47.20.1. Solution X Y Plot D ialo g Box The Solution X Y Plot dialo g box allo ws you t o displa y zone , sur face and file da ta in an X Y plot f ormat. See Steps f or G ener ating S olution X Y Plots (p.2864 ) for details ab out the it ems b elow. You c an also acc ess the Solution X Y P lot dialo g box thr ough the Postpr ocessing ribbon tab . Postpr ocessing → Plots → XY Plot → New... 3703Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Plots Task P ageControls XY Plot N ame is the name f or a solution X Y plot definition. You c an sp ecify a name or use the default name xy- plot-id.This c ontrol app ears only f or solution X Y plot definitions . Options contains check butt ons tha t control the pr esen tation of no de or c ell-a veraged v alues , the selec tion of axis func tions , and the abilit y to wr ite the plot da ta to a file . Node Values toggles the no de a veraging of the da ta pr esen ted in the plot. If the option is inac tive, cell v alues ar e presen ted. See Choosing N ode or C ell Values (p.2868 ) for details . Position on X A xis, Position on Y Axis set the -axis or -axis func tion t o be the p osition. If one of these options is tur ned on, the other will automa tically b e tur ned off .You c an tur n both options off t o gener ate a plot of one flo w-field func tion vs. another , selec ting the func tion f or each axis using the X Axis F unc tion and Y Axis F unc tion drop- down lists . Write to File activates the file-wr iting option. When this option is selec ted, the Plot push butt on will change t o Write.... Clicking on the Write... butt on will op en the Selec t File dialo g box (The S elec t File D ialog Box (p.569) and The S elec t File D ialog Box (Windo ws) (p.569)), in which y ou c an sp ecify a name and save a file c ontaining the plot da ta.The format of this file is descr ibed in XY Plot F ile F ormat (p.2874 ). Order P oints specifies tha t plot da ta b eing sa ved t o a file should b e sor ted in or der of asc ending axis v alue .This option is a vailable only when the Write to File option is tur ned on. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3704Task P age R eference GuidePlot D irection contains inputs f or defining the plot dir ection. If Direction Vector (the default) is selec ted in the X A xis F unc tion or Y A xis F unc tion drop-do wn list (whiche ver is the p osition axis), the inputs ar e the c omp onen ts of the dir ection v ector.The position axis of the plot will ha ve coordina te values tha t correspond t o the dot pr oduc t of the da ta coordina te vector with the plot dir ection v ector. See Steps f or G ener ating S olution X Y Plots (p.2864 ) for details . X is the c omp onen t in the direction. Y is the c omp onen t in the direction. Z is the c omp onen t in the direction. If Curve Length is selec ted in the X A xis F unc tion or Y A xis F unc tion drop-do wn list (whiche ver is the p osition axis), the inputs ar e the dir ection along the length of the sur face selec ted in the Surfaces list. See Steps f or G ener ating S olution X Y Plots (p.2864 ) for details . Default specifies the plot dir ection as the dir ection of incr easing cur ve length. Reverse specifies the plot dir ection as the dir ection of decr easing cur ve length. Show displa ys the selec ted sur face in the gr aphics windo w, mar king the star t of the sur face with a blue dot and the end of the sur face with a r ed dot. ANSY S Fluen t will also displa y arrows on the sur face showing the dir ection in which the v ariable will b e plott ed. Y Axis F unc tion, X A xis F unc tion contain lists of solution v ariables tha t can b e used f or the or axis of the plot. If the Position on X Axis option is tur ned on, X Axis F unc tion will b ecome a single dr op-do wn list , containing t wo options: Direction Vector (to plot the selec ted v ariable as a func tion of p osition along a sp ecified dir ection v ector) and Curve Length (to plot the selec ted v ariable as a func tion of p osition along the length of a sp ecified curvilinear sur face). See Steps f or G ener ating S olution X Y Plots (p.2864 ) for details . Likewise , if Position on Y A xis is tur ned on, Y A xis F unc tion will b ecome a single dr op-do wn list containing Direction Vector and Curve Length . If both Position on X A xis and Position on Y Axis are tur ned off , you c an selec t field func tions f or b oth ax es using the X A xis F unc tion and Y Axis F unc tion lists . Note When r unning the par allel v ersion of ANSY S Fluen t,Curve Length is only supp orted when the cur vilinear sur face is c ontained within a single par tition. File D ata is a selec table list of the plot titles asso ciated with the loaded e xternal da ta files .You ma y cho ose an y numb er of files f or the da ta plot. The files ar e loaded using the Load F ile... push butt on.The format of 3705Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Plots Task P agethese files is pr esen ted in XY Plot F ile F ormat (p.2874 ). See Including Ex ternal D ata in the S olution X Y Plot (p.2868 ) for details . Load F ile... opens the Selec t File dialo g box (The S elec t File D ialog Box (p.569)), in which y ou c an selec t the plot file to be read. See Including Ex ternal D ata in the S olution X Y Plot (p.2868 ) for details . After the e xternal file is loaded , its plot title will b e displa yed in the File D ata list. Free D ata remo ves the files selec ted in the File D ata list. Surfaces is a selec table list of sur faces in the solution domain. You ma y cho ose an y numb er of sur faces for the da ta plot. New S urface is a dr op-do wn list butt on tha t contains a list of sur face options: Point opens the Point Sur face Dialog Box (p.3898 ). Line/R ake opens the Line/R ake Sur face Dialog Box (p.3847 ). Plane opens the Plane Sur face Dialog Box (p.3895 ). Quadr ic opens the Quadr ic Sur face Dialog Box (p.3899 ). Iso-S urface opens the Iso-Sur face Dialog Box (p.3842 ). Iso-C lip opens the Iso-C lip D ialog Box (p.3841 ). Structural P oint opens the Structural Point Sur face Dialog Box (p.3928 ). Plot plots the sp ecified sur face and/or file da ta in the ac tive gr aphics windo w using the cur rent axis and cur ve attribut es. If the Write to File option is tur ned on, this butt on b ecomes the Write... butt on. Write... opens the Selec t File dialo g box (The S elec t File D ialog Box (p.569)), in which y ou c an sa ve the plot da ta to a file .This butt on r eplac es the Plot butt on when the Write to File option is tur ned on. Axes... opens the Axes D ialog Box (p.3717 ), which allo ws you t o cust omiz e the plot ax es. Curves... opens the Curves D ialog Box (p.3720 ), which allo ws you t o cust omiz e the cur ves used in the X Y plot. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3706Task P age R eference GuideSave/Plot plots the sp ecified sur face and/or file da ta in the ac tive gr aphics windo w using the cur rent axis and cur ve attribut es and sa ves the X Y plot definition. This butt on app ears only f or solution X Y plot definitions and replac es the Plot butt on. 47.20.2. Hist ogram D ialo g Box The Hist ogram dialo g box allo ws you t o cr eate hist ograms of selec ted geometr ic or ph ysical da ta. See Steps f or G ener ating Hist ogram P lots (p.2876 ) for details ab out the it ems b elow. Controls Options contains the check butt ons f or cur rent hist ogram options . Auto Range toggles the abilit y to sp ecify the minimum and maximum r ange of sc alar v alues in the hist ogram print or plot. If the option is not ac tive, the Min and Max fields ar e editable , and y ou ma y sp ecify the desir ed r ange . If the option is ac tive, the r ange is defined b y the minimum and maximum v alues in the c omputa tional domain. Global R ange toggles the abilit y to sp ecify the minimum and maximum v alues on the r ange of v alues on the selec ted surfaces, rather than in the en tire domain. Divisions sets the numb er of da ta in tervals tha t will e xist in the hist ogram. Zone Types contains a list of a vailable fac e or c ell z one t ypes. 3707Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Plots Task P ageAxes... opens the Axes D ialog Box (p.3717 ), which allo ws you t o cust omiz e the plot ax es. Curves... opens the Curves D ialog Box (p.3720 ), which allo ws you t o cust omiz e the cur ves used in the hist ogram plot. Hist ogram of contains a list of sc alar quan tities tha t can b e used in the hist ogram. Min displa ys or allo ws definition of the minimum v alue of the selec ted sc alar quan tity used in the hist ogram. Max displa ys or allo ws definition of the maximum v alue of the selec ted sc alar quan tity used in the hist ogram. Zones contains a list of a vailable fac e or c ell z ones . Print displa ys the hist ogram in terval. Plot displa ys a plot of the p ercentage of the t otal numb er of c ells v ersus the sc alar quan tity in the ac tive graphics windo w. Comput e comput es the minimum and maximum c ell v alues of the selec ted sc alar quan tity.The v alues ar e displa yed in Min and Max. 47.20.3. File X Y Plot D ialo g Box The File X Y Plot dialo g box allo ws you t o displa y da ta read fr om one or mor e files in an abscissa/or- dina te plot f orm.The f ormat of the plot file is descr ibed in XY Plot F ile F ormat (p.2874 ). See Steps f or Gener ating X Y Plots of D ata in Ex ternal F iles (p.2869 ) for details ab out the it ems b elow. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3708Task P age R eference GuideControls Files contains op erations and inf ormation r elated t o the loaded files . Load ... opens the Selec t File dialo g box, wher e you c an selec t the file(s) y ou w ant to plot. Remo ve remo ves the selec ted file fr om the File N ames list. This also r emo ves an y cur ves asso ciated with tha t file. File N ames lists the files tha t you ha ve loaded . Data S ets lists the a vailable da ta sets f or files (t ypic ally .xy ) tha t contain t wo columns monit oring the same value a t diff erent locations .You c an selec t which da ta sets y ou w ant to plot b y selec ting/de-selec ting the list ed it ems . Variables lists X and Y variables f or the selec ted file . X Axis Variable lists the v ariables tha t you c an selec t for the X axis .The highligh ted X v ariable will b e added t o the Curve Inf ormation list in c oordina tion with the selec ted Y Axis Variables . Changing the selec ted X Axis Variable updates all the r elated cur ves sho wn in the Curve Inf ormation list. Y Axis Variables lists the v ariables tha t you c an selec t for the Y axis .The highligh ted Y variables will b e added t o the Curve Inf ormation list in c oordina tion with the selec ted X Axis Variable . Changing the selec ted Y Axis Variables updates ho w man y cur ves ar e sho wn in the Curve Inf ormation list. 3709Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Plots Task P ageCurves lists wha t items will b e plott ed and ho w the y will b e lab eled in the legend . Curve Inf ormation lists the cur ves tha t will b e plott ed. Information ab out each cur ve is sho wn in the f ollowing or der: 1.The name of the file wher e the da ta or igina ted. 2.[2 column file (t ypic ally .xy) only] The lo cation on the mo del wher e the da ta or igina ted. 3.X Variable . 4.Y Variable . Legend N ames lists the name f or each cur ve tha t will b e list ed in the legend when the plot is displa yed in the graphics windo w. (see Change L egend E ntry to lear n ho w to change the legend name f or a cur ve). Remo ve remo ves the selec ted cur ve from the Curve Inf ormation list. Change L egend E ntry allows you t o change the name tha t will app ear in the plot legend in the gr aphics windo w for a par- ticular cur ve.To use: 1.Selec t a name in the Legend N ames list. 2.Enter the new name in the t ext en try box to the r ight of the Change L egend E ntry butt on. 3.Click Change L egend E ntry. Plot contains t ext en try boxes for the v arious plot lab els. Title lets y ou en ter a title f or the plot. Legend L abel lets y ou en ter a title f or the legend . X Axis L abel lets y ou lab el the X axis . Y Axis L abel lets y ou lab el the Y axis . Plot click Plot to plot the da ta list ed in the Curve Inf ormation list. Axes... opens the Axes D ialog Box (p.3717 ), which allo ws you t o cust omiz e the plot ax es. Curves... opens the Curves D ialog Box (p.3720 ), which allo ws you t o cust omiz e the cur ves used in the X Y plot. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3710Task P age R eference Guide47.20.4. Plot P rofile D ata D ialo g Box The Plot P rofile D ata dialo g box allo ws you t o displa y an X Y plot of the or iginal da ta p oints of a boundar y pr ofile b efore it is in terpolated on to the c ell fac es of a b oundar y. See Steps f or G ener ating Plots of P rofile D ata (p.2871 ) for details ab out the it ems b elow. Controls Profile contains a selec table list of a vailable pr ofiles .When a pr ofile is selec ted its a vailable fields ar e displa yed under Y Axis F unc tion . Y Axis F unc tion contains a selec table list of the fields a vailable in the selec ted pr ofile tha t can b e used f or the axis of the plot. X Axis F unc tion contains a selec table list of the v ariables tha t can b e used f or the axis of the plot. Plot displa ys an X Y plot of the da ta p oints fr om the selec ted pr ofile . Axes... opens the Axes D ialog Box (p.3717 ), which allo ws you t o cust omiz e the plot ax es. Curves... opens the Curves D ialog Box (p.3720 ), which allo ws you t o cust omiz e the cur ves used in the X Y plot. 47.20.5. Plot In terpolated D ata D ialo g Box The Plot In terpolated D ata dialo g box allo ws you t o displa y an X Y plot of the v alues assigned t o the cell fac es when a pr ofile file has b een in terpolated on a b oundar y. See Steps f or G ener ating P lots of Interpolated P rofile D ata (p.2872 ) for details ab out the it ems b elow. 3711Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Plots Task P ageControls Zones contains a selec table list of the z ones f or which a pr ofile field has b een set as one or mor e of the par amet ers are displa yed under Y Axis F unc tion . Y Axis F unc tion contains a selec table list of the pr ofile-r elated par amet ers in the selec ted z one tha t can b e used f or the axis of the plot. The name of the par amet er will b e the same as tha t of the dr op-do wn list in the boundar y condition dialo g box from which the pr ofile field w as selec ted. X Axis F unc tion contains a selec table list of the geometr y variables tha t can b e used f or the axis of the plot. Plot displa ys an X Y plot of the c ell fac e values (as in terpolated fr om the da ta p oints of the pr ofile file) of the selec ted z one . Axes... opens the Axes D ialog Box (p.3717 ), which allo ws you t o cust omiz e the plot ax es. Curves... opens the Curves D ialog Box (p.3720 ), which allo ws you t o cust omiz e the cur ves used in the X Y plot. 47.20.6. Four ier Transf orm D ialo g Box The Four ier Transf orm dialo g box allo ws you t o analyz e your time dep enden t da ta using the F ast Fourier Transf orm (FFT ) algor ithm. See Fast F ourier Transf orm (FFT ) Postpr ocessing (p.2898 ) for details about the it ems b elow. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3712Task P age R eference GuideControls Options lets y ou wr ite the FFT da ta to a file or displa y the FFT da ta in a gr aphics windo w. Write FFT t o File allows you t o wr ite out the FFT da ta dir ectly t o a file .When selec ted, the Plot FFT ... butt ons b ecomes the Write FFT ... butt on. Acoustics A naly sis enables the ac oustics-r elevant spectrum options (sound pr essur e level sp ectra and fr equenc y band char ts), and sp ecifies tha t the o verall sound pr essur e level is c alcula ted and displa yed in the c onsole when y ou plot or wr ite the FFT da ta. All dB-measur ed quan tities ar e based on the Referenc e Acoustic Pressur e. Process Options contains options t o analyz e signal da ta. Process Rec eiver allows you t o analyz e receiver da ta st ored in memor y. Process F ile D ata allows you t o analyz e signal da ta fr om an e xisting input file . Y Axis F unc tion contains a list fr om which y ou c an selec t the func tion f or the axis . X Axis F unc tion contains a list fr om which y ou c an selec t the func tion f or the axis . 3713Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Plots Task P ageRec eiver contains a list of r eceivers fr om which y ou c an selec t when the Process Rec eiver option is enabled . Plot/M odify Input S ignal... opens the Plot/M odify Input S ignal D ialog Box (p.3715 ), which y ou c an use t o plot the input signal, as w ell as cust omiz e the da ta set and define sp ectrum smo othing in pr epar ation f or applying the FFT algor ithm. Referenc e Acoustic P ressur e allows you t o sp ecify the r eference ac oustic pr essur e (for e xample , in Equa tion 40.41 (p.2905 )) used t o calcula te the dB-measur ed quan tities when the Acoustics A naly sis option is enabled . Plot Title lets y ou cr eate a new title or edit the or iginal title f or the FFT plot. By default , ANSY S Fluen t adds the string “Spectral Analy sis of ” to the title or iginally applied t o the input signal plot. Y Axis L abel allows you t o create a new axis lab el or edit the or iginal axis lab el. By default , the Y Axis L abel cor- responds t o the selec tion in the Y Axis F unc tion drop-do wn list. X Axis L abel allows you t o create a new axis lab el or edit the or iginal axis lab el. By default , the X Axis L abel corres- ponds t o the selec tion in the X Axis F unc tion drop-do wn list. Y Axis Variable if your input r eport file c ontains multiple r eport definitions , this allo ws you t o sp ecify the axis v ariable . X Axis Variable if your input r eport file c ontains multiple r eport definitions , this allo ws you t o sp ecify the axis v ariable . Files lists the loaded input signal da ta files . Load Input F ile... loads an input signal da ta file in to ANSY S Fluen t for FFT analy sis.The input file is list ed under Files. Free F ile D ata remo ves da ta fr om FFT analy sis onc e the input signal da ta file is selec ted in the Files list. Plot FFT displa ys the FFT da ta in a gr aphic windo w and , if Acoustics A naly sis is enabled , calcula tes the o verall sound pr essur e level in dB (based on the Referenc e Acoustic P ressur e) and displa ys it in the c onsole . If the Write FFT t o File option is selec ted, then this butt on b ecomes the Write FFT butt on, which op ens a file selec tion dialo g box so tha t you wr ite the FFT da ta to a file . Write FFT opens The S elec t File D ialog Box (p.569) in which y ou c an sp ecify a name and sa ve the FFT da ta to a file . If Acoustics A naly sis is enabled , the o verall sound pr essur e level will b e calcula ted in dB (based on the Referenc e Acoustic P ressur e) and displa yed in the c onsole a t this time . If the Write FFT t o File option is selec ted, then the Plot FFT butt on changes t o the Write FFT butt on. Axes... opens the Axes D ialog Box (p.3717 ), which allo ws you t o cust omiz e the plot ax es. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3714Task P age R eference GuideCurves... opens the Curves D ialog Box (p.3720 ), which allo ws you t o cust omiz e the cur ves used in the plot. 47.20.7. Plot/M odify Input S ignal D ialo g Box The Plot/M odify Input S ignal dialo g box allo ws you t o plot the input signal, as w ell as cust omiz e the data set and define sp ectrum smo othing in pr epar ation f or applying the FFT algor ithm. It is op ened from the Fourier Transf orm D ialog Box (p.3712 ). See Using the FFT U tility (p.2901 ) for details ab out the items b elow. Controls Options allows you t o pr ocess some or all of the input signal da ta. Clip t o Range allows you t o analyz e a p ortion of the input signal b y sp ecifying da ta range . Subtr act Mean Value reduc es y axis quan tities b y the mean v alue of the r elevant signal pr operty. Subdivide in to Segmen ts enables / disables sp ectrum smo othing , which c an suppr ess spur ious amplitude fluc tuations in the Fourier sp ectrum b y splitting the input signal in to multiple o verlapping segmen ts, so tha t ANSY S Fluen t can apply the FFT algor ithm on each segmen t and then a verage the r esulting sp ectra.The spectrum smo othing is c ontrolled b y the settings in the Segmen t Control group b ox. See Customizing the Input and D efining the S pectrum S moothing (p.2902 ) for fur ther details . 3715Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Plots Task P ageSignal S tatistics displa ys signal inf ormation. Min displa ys the minimum v alue f or the input signal. Max displa ys the maximum v alue f or the input signal. Mean displa ys the a verage v alue f or the input signal. Varianc e displa ys the v arianc e for the input signal. Numb er of S amples displa ys the t otal numb er of samples in the input signal da ta set. Min F requenc y displa ys the finest p ossible fr equenc y resolution f or the input signal. X Axis R ange allows for a p ortion of the input signal t o be analyz ed when the Process the whole da ta option is tur ned off. Min specifies a minimum v alue f or the axis . Max specifies a maximum v alue f or the axis . Set D efaults resets the axis minimum and maximum v alues t o their or iginal v alue and tur ns on the Process the whole da ta option. Signal P lot Title lets y ou cr eate a new title or edit the or iginal title f or the input signal plot. By default , the Signal P lot Title corresponds with the title or iginally applied t o the input signal plot. Y Axis L abel allows you t o create a new axis lab el or edit the or iginal axis lab el. By default , the Y Axis L abel cor- responds with the axis lab el or iginally applied t o the input signal plot. X Axis L abel allows you t o create a new axis lab el or edit the or iginal axis lab el. By default , the X Axis L abel corres- ponds with the axis lab el or iginally applied t o the input signal plot. Y Axis Variable if your input r eport file c ontains multiple r eport definitions , this allo ws you t o sp ecify the axis v ariable . X Axis Variable if your input r eport file c ontains multiple r eport definitions , this allo ws you t o sp ecify the axis v ariable . Windo w lets y ou sp ecify a windo wing t echnique t o remo ve disc ontinuities in the FFT c alcula tion. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3716Task P age R eference GuideNone applies no windo wing t echnique .This is the default setting . Hamming applies the Hamming t echnique . Hanning applies the Hanning t echnique . Barlett applies the B arlett t echnique . Black man applies the B lack man t echnique . Segmen t Control provides settings tha t control the sp ectrum smo othing when Subdivide in to Segmen ts is enabled . Control M etho d allows you t o sp ecify ho w you w ant to define the segmen t siz e from the f ollowing: Samples bases the segmen t siz e on the Samples p er S egmen t. Frequenc y bases the segmen t siz e on the Frequenc y Resolution in H ertz units . Samples p er S egmen t defines the numb er of samples in each segmen t when Samples is selec ted fr om the Control M etho d list. Frequenc y Resolution defines the desir ed fr equenc y resolution in H ertz units when Frequenc y is selec ted fr om the Control M etho d list. Overlap ranges fr om 0 t o 1 and defines ho w much adjac ent segmen ts overlap.This setting is applic able r e- gardless of which Control M etho d you selec t. Apply/P lot applies an y changes y ou ha ve made in the dialo g box and displa ys the input signal da ta in a gr aphics windo w. Axes... opens the Axes D ialog Box (p.3717 ), which allo ws you t o cust omiz e the plot ax es. Write... opens The S elec t File D ialog Box (p.569), in which y ou c an sa ve the signals t o a file . 47.20.8. Axes D ialo g Box The Axes dialo g box allo ws you t o indep enden tly c ontrol the char acteristics of the or dina te and abscissa on an X Y plot or hist ogram. You c an change the lab els, scale, range , numb er format, and major and minor r ules visibilit y and app earance. Note tha t the title f ollowing Axes in the dialo g box indic ates 3717Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Plots Task P agewhich plot en vironmen t you ar e changing .You c an set diff erent par amet ers f or each t ype of plot tha t ANSY S Fluen t can gener ate. See Using the A xes D ialog Box (p.2878 ) for details ab out the it ems b elow. Controls Axis contains check butt ons tha t allo w you t o set abscissa ( -axis) or or dina te ( -axis) char acteristics . X allows you t o sp ecify the abscissa char acteristics . Y allows you t o sp ecify the or dina te char acteristics . Label defines the char acter str ing tha t will lab el the ac tive axis (the one selec ted in Axis) in the displa y. Options contains check butt ons tha t (de)ac tivate sc ale, range , major r ules , and minor r ules . Log toggles lo garithmic sc aling of the ac tive axis . By default , decimal sc aling is used . Auto Range toggles aut oma tic c omputa tion of the r ange of the ac tive axis . If you deac tivate this option, you ma y input the Minimum and Maximum values in the Range box. Major R ules toggles the displa y of major r ules on the ac tive axis . Major r ules ar e the hor izontal or v ertical lines that mar k the pr imar y da ta divisions and span the whole plot windo w to pr oduce a “grid.” Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3718Task P age R eference GuideMinor R ules toggles the displa y of minor r ules on the ac tive axis . Minor r ules ar e the hor izontal or v ertical lines that mar k the sec ondar y da ta divisions and span the whole plot windo w to pr oduce a “grid.” Numb er F ormat contains c ontrols f or changing the f ormat of the da ta lab els on the ac tive axis . Data lab els ar e the char acter strings used t o define the pr imar y da ta divisions on the ax es. Type sets the f orm of the da ta lab els.You ma y selec t from a dr op-do wn list of options , including the f ollow- ing: gener al displa ys the r eal v alue with either floa t or e xponen tial f orm based on the siz e of the numb er and the defined Precision . floa t displa ys the r eal v alue with an in tegral and fr actional par t (for e xample , 1.0000), wher e the numb er of digits in the fr actional par t is det ermined b y Precision . exponen tial displa ys the r eal v alue with a man tissa and e xponen t (for e xample , 1.0e-02), wher e the numb er of digits in the fr actional par t of the man tissa is det ermined b y Precision . Precision defines the numb er of fr actional digits displa yed in the da ta lab els. Range contains the r ange or e xtents of the ac tive axis .To set the r ange manually , you must tur n off Auto Range . Other wise the e xtents ar e comput ed aut oma tically. Minimum sets the minimum da ta value f or the ac tive axis . Maximum sets the maximum da ta value f or the ac tive axis . Major R ules contains c ontrols f or mo difying the app earance of the major r ules .To use these c ontrols y ou must ac tivate Major R ules in the Options list. Color sets the c olor of the major r ules fr om a dr op-do wn list with numer ous c olor selec tions . Weigh t sets the line thick ness of the major r ule. A line of w eigh t 1.0 is nor mally 1 pix el wide . A w eigh t of 2.0 would mak e the line t wice as thick (2 pix els wide). Minor R ules contains c ontrols f or mo difying the app earance of the minor r ules .To use these c ontrols y ou must ac tivate Minor R ules in the Options list. Color sets the c olor of the minor r ules fr om a dr op-do wn list with numer ous c olor selec tions . 3719Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Plots Task P ageWeigh t sets the line thick ness of the minor r ule. A line of w eigh t 1.0 is 1 pix el wide . A w eigh t of 2.0 w ould mak e the line t wice as thick (2 pix els wide). 47.20.9. Curves D ialo g Box The Curves dialo g box allo ws you t o mo dify the app earance of the lines and mar kers used in X Y plots . Note tha t the title f ollowing Curves in the dialo g box indic ates which plot en vironmen t you ar e changing .You c an set diff erent par amet ers f or each t ype of plot tha t ANSY S Fluen t can gener ate. See Using the C urves D ialog Box (p.2879 ) for details ab out the it ems b elow. Controls Curve # defines the ac tive cur ve numb er.The pr esen t and futur e mar ker and line st yles apply t o the defined cur ve numb er.The cur ves ar e numb ered sequen tially , star ting fr om 0. For e xample , if you w ere plotting flo w- field v alues on t wo zones , the first z one w ould b e cur ve 0, and the sec ond , cur ve 1. If the plot c ontains only one cur ve, the Curve # is set t o 0 and is not editable . Sample displa ys a single mar ker and line with the cur rent style a ttribut es. Line S tyle contains c ontrols f or mo difying the app earance of the ac tive cur ve. Pattern sets the pa ttern of the ac tive cur ve. A dr op-do wn list allo ws you t o set the line pa ttern. Except f or center and phan tom lines , the list displa ys examples of the pa ttern choic es. A center line alt ernates a very long dash and a shor t dash and a phan tom line alt ernates a v ery long dash and a double shor t dash. Color sets the c olor of the ac tive cur ve. A dr op-do wn list allo ws you t o selec t from a list of c olor names . Weigh t sets the thick ness of the ac tive cur ve. A line w eigh t of 1.0 is nor mally 1 pix el wide .Therefore, a w eigh t of 2.0 w ould mak e the line t wice as thick (2 pix els wide). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3720Task P age R eference GuideMarker S tyle contains c ontrols f or mo difying the app earance of the ac tive cur ve’s mar ker. Symb ol sets the symb ol used t o mar k da ta.You c an selec t the symb ol fr om a dr op-do wn list tha t contains all the symb ol choic es.The Sample box will allo w you t o experimen t with v arious mar kers. For e xample , in plotting pr essur e-coefficien t da ta on the upp er and lo wer sur faces of an air foil, the symb ol /*\ (filled-in up ward-pointing tr iangle) c ould b e used f or the mar ker represen ting the upp er sur face da ta, and the symb ol \*/ (filled-in do wnw ard-pointing tr iangle) c ould b e used f or the mar ker represen ting the lo wer sur face da ta. Color sets the c olor of the mar ker on the ac tive line numb er. A dr op-do wn list allo ws you t o selec t from a list of c olor names . Size sets the siz e of the da ta mar ker. A symb ol of siz e 1.0 is 3.0% of the heigh t of the displa y scr een, except for the “.” symb ol, which is alw ays one pix el. 47.21. Rep orts Task P age The Rep orts task page allo ws you t o set up r eports for y our CFD simula tion. Reports can b e compiled for flux es, forces, projec ted ar eas, sur face and v olume in tegrals, among others . See Reporting A lphanu- mer ic D ata (p.2909 ) for mor e inf ormation. Controls Rep orts displa ys a list of a vailable r eport types in ANSY S Fluen t. 3721Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Reports Task P ageYou c an double-click an it em in the Rep orts list t o op en the c orresponding dialo g box, or y ou c an selec t the it em in the list and click the Set U p... butt on. Fluxes selec ting this it em and click ing the Set U p... butt on op ens the Flux R eports D ialog Box (p.3723 ). Forces selec ting this it em and click ing the Set U p... butt on op ens the Force Reports D ialog Box (p.3724 ). Projec ted A reas selec ting this it em and click ing the Set U p... butt on op ens the Projec ted Sur face Areas D ialog Box (p.3725 ). Surface In tegrals selec ting this it em and click ing the Set U p... butt on op ens the Surface Integrals D ialog Box (p.3726 ). Volume In tegrals selec ting this it em and click ing the Set U p... butt on op ens the Volume In tegrals D ialog Box (p.3730 ). Discr ete Phase allows you t o report on one of the f ollowing thr ee report types: Sample selec ting this it em and click ing the Set U p... butt on op ens the Sample Trajec tories D ialog Box (p.3732 ). Hist ogram selec ting this it em and click ing the Set U p... butt on op ens the Trajec tory Sample Hist ograms D ialog Box (p.3733 ). Summar y selec ting this it em and click ing the Set U p... butt on op ens the Particle Summar y Dialog Box (p.3736 ). Heat Exchanger selec ting this it em and click ing the Set U p... butt on op ens the Heat Exchanger R eport Dialog Box (p.3736 ). Set U p... opens the dialo g box corresponding t o the selec ted it em in the Rep orts list. Paramet ers... opens the Paramet ers D ialog Box (p.3738 ). For additional inf ormation, see the f ollowing sec tions: 47.21.1. Flux R eports D ialog Box 47.21.2. Force Reports D ialog Box 47.21.3. Projec ted Sur face Areas D ialog Box 47.21.4. Sur face Integrals D ialog Box 47.21.5. Volume In tegrals D ialog Box 47.21.6. Sample Trajec tories D ialog Box 47.21.7. Trajec tory Sample Hist ograms D ialog Box 47.21.8. Particle Summar y Dialog Box 47.21.9. Heat Exchanger R eport Dialog Box 47.21.10. Paramet ers D ialog Box 47.21.11. Use Input P aramet er in Scheme P rocedur e Dialog Box 47.21.12. Use Input P aramet er for UDF D ialog Box 47.21.13. Rename D ialog Box 47.21.14. Paramet er Expr ession D ialog Box Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3722Task P age R eference Guide47.21.15. Save Output P aramet er D ialog Box 47.21.1. Flux Rep orts D ialo g Box The Flux Rep orts dialo g box allo ws you t o comput e the mass flo w rate, hea t transf er rate, and r adia tion heat transf er rate on selec ted b oundar y zones . See Fluxes Through B oundar ies (p.2937 ) for details . Controls Options contains the f ollowing option butt ons: Mass F low R ate turns on the c omputa tion of the mass flo w rate for the selec ted b oundar y zones . Total H eat Transf er R ate turns on the c omputa tion of the t otal hea t transf er rate for the selec ted b oundar y zones . Total S ensible H eat Transf er R ate turns on the c omputa tion of the t otal sensible hea t transf er rate for the selec ted b oundar y zones . It reports the t otal ener gy flux as defined in Equa tion 5.2 in the Theor y Guide . Radia tion H eat Transf er R ate turns on the c omputa tion of the r adia tion hea t transf er rate for the selec ted b oundar y zones . Film M ass F low R ate (available only when the E uler ian w all film mo del is enabled) tur ns on the c omputa tion of the mass flow rate for the selec ted b oundar y zone(s). Film H eat Transf er R ate (available only when the E uler ian w all film mo del is enabled) tur ns on the c omputa tion of the film heat transf er rate for the selec ted b oundar y zone(s). 3723Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Reports Task P ageSave Output P aramet er... opens the Save Output P aramet er D ialog Box (p.3743 ). Boundar ies contains a selec table list of v alid b oundar y zones f or flux r eporting . Results displa ys the r esults of the selec ted flux c omputa tion f or each b oundar y zone selec ted.The summa tion of the individual z one flux r esults is displa yed in the b ox below the Results list. Comput e comput es the flux f or each of the selec ted b oundar y zones and up dates Net Results (for e xample , in kg/s,W, and so on) and other r eports, for e xample ,Heat of Reac tion S our ce. Write... opens the Selec t File dialo g box (The S elec t File D ialog Box (p.569) and The S elec t File D ialog Box (Win- dows) (p.569)), which y ou c an use t o sa ve the r eported v alues t o a file . 47.21.2. Force Rep orts D ialo g Box The Force Rep orts dialo g box allo ws you t o comput e the f orces along a sp ecified v ector, momen ts about a sp ecified c enter, and the c oordina tes of the c enter of pr essur e for selec ted w all z ones . See Forces on B oundar ies (p.2942 ) for details . Controls Options contains option butt ons tha t control computa tion of the f orces, momen ts, or c enter of pr essur e. Forces enables the c omputa tion of the pr essur e and visc ous f orces. Momen ts enables the c omputa tion of the pr essur e and visc ous momen ts. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3724Task P age R eference GuideCenter of P resur e enables the c omputa tion of the a verage lo cation of the pr essur e. Direction Vector contains the c omp onen ts of the f orce vector.This lab el is visible when the Forces option butt on is ac tive. X,Y,Z are the c omp onen ts of the f orce vector along which the f orces will b e comput ed. Momen t Center contains the C artesian c oordina tes of the momen t center.This lab el is visible when the Momen ts option butt on is ac tive. X,Y,Z are the C artesian c oordina tes of the momen t center ab out which momen ts will b e comput ed. Momen t Axis contains the C artesian c oordina tes of the momen t axis .This lab el is visible when the Momen ts option butt on is ac tive. X,Y,Z are the C artesian c oordina tes of the momen t axis ab out which momen ts will b e comput ed. Coordina te contains the v alue of the C artesian c oordina te tha t is fix ed.This lab el is visible when the Center of P ressur e option butt on is ac tive. X,Y,Z are the C artesian c oordina tes, one of which will b e fix ed. Value (n) is the p oint wher e the selec ted C artesian c oordina te will b e fix ed. Wall Z ones contains a selec table list of w all z ones .The force or momen t inf ormation is pr inted f or each z one , and then a t otal f orce or momen t for all the z ones is pr esen ted. Save Output P aramet er... opens the Save Output P aramet er D ialog Box (p.3743 ). Print displa ys (in the c onsole) the pr essur e, visc ous (if appr opriate), and t otal f orces or momen ts, and the pressur e, visc ous, and t otal f orce coefficien ts along the sp ecified f orce vector or momen t center for the selec ted w all z ones .The c enter of pr essur e coordina tes will pr int to the c onsole when the Center of Pressur e option is ac tivated. Write... opens The S elec t File D ialog Box (p.569), which y ou c an use t o sa ve the r eported v alues t o a file . 47.21.3. Projec ted S urface Areas D ialo g Box The Projec ted S urface Areas dialo g box allo ws you t o comput e an estima ted ar ea of the pr ojec tion of selec ted sur faces along the , , or axis . See Projec ted Sur face Area C alcula tions (p.2946 ) for details . 3725Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Reports Task P ageControls Projec tion D irection indic ates the dir ection along which t o pr ojec t the sur face. Min F eature Size specifies the length of the smallest f eature in the geometr y tha t you w ant to resolv e in the ar ea c alcula tion. Area displa ys the c omput ed pr ojec ted ar ea. Surfaces contains a list of e xisting sur faces.You c an selec t the sur face(s) f or which the pr ojec ted ar ea is t o be cal- cula ted in this list. Comput e comput es the ar ea of the selec ted sur faces pr ojec ted along the selec ted dir ection. The ar ea will b e pr inted in the Area box and in the c onsole windo w. 47.21.4. Surface In tegrals D ialo g Box The Surface In tegrals dialo g box allo ws you t o comput e the ar ea, mass and v olume flo w rate, standar d deviation, integral, flow rate, area-w eigh ted a verage, cust om v ector-based flux, cust om v ector flux, cust om v ector-w eigh ted a verage, mass-w eigh ted a verage, sum, facet a verage, facet minimum/maximum, unif ormity inde x (w eigh ted b y area or mass), vertex average, or v ertex minimum/maximum quan tity of a sp ecified field v ariable on a selec ted list of sur faces. See Surface In tegration (p.2947 ) for details . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3726Task P age R eference GuideControls Rep ort Type contains dr op-do wn list tha t has options tha t control the metho d of sur face integration. Area turns on the c omputa tion of the sur face area. Area-W eigh ted A verage turns on the c omputa tion of the ar ea-w eigh ted a verage on the sur face(s). Custom Vector B ased F lux turns on the c omputa tion of the v ector-based flo w rate of a quan tity thr ough the sur face(s). Custom Vector F lux turns on the c omputa tion of the flo w rate on a v ector thr ough the sur face(s). Custom Vector Weigh ted A verage turns on the c omputa tion of v ector-w eigh ted a verage of a quan tity on the sur face(s). Facet A verage turns on the c omputa tion of the fac et-a veraged quan tity on the sur face(s). Facet M inimum turns on the c omputa tion of the fac et minimum of a quan tity on the sur face(s). 3727Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Reports Task P ageFacet M aximum turns on the c omputa tion of the fac et maximum of a quan tity on the sur face(s). Flow R ate turns on the c omputa tion of the flo w rate thr ough the sur face(s). Integral turns on the c omputa tion of the in tegral on the sur face(s). Mass F low R ate turns on the c omputa tion of the mass flo w rate thr ough the sur face(s). Mass-W eigh ted A verage turns on the c omputa tion of the mass-a veraged quan tity on the sur face(s). Standar d D eviation turns on the c omputa tion of the standar d de viation of a sp ecified field v ariable on a sur face. Sum turns on the c omputa tion of the summed quan tity on the sur face(s). Uniformit y Inde x - M ass Weigh ted turns on the c omputa tion of the mass-w eigh ted unif ormity inde x of a quan tity on the sur face(s). Uniformit y Inde x - A rea Weigh ted turns on the c omputa tion of the ar ea-w eigh ted unif ormity inde x of a quan tity on the sur face(s). Vertex Average turns on the c omputa tion of the v ertex-averaged quan tity on the sur face(s). Vertex M inimum turns on the c omputa tion of the v ertex minimum of a quan tity on the sur face(s). Vertex M aximum turns on the c omputa tion of the v ertex maximum of a quan tity on the sur face(s). Volume F low R ate turns on the c omputa tion of the v olume flo w rate thr ough the sur face(s). Custom Vectors allows you t o define cust om v ectors if y ou selec ted Custom Vector B ased F lux,Custom Vector F lux, or Custom Vector Weigh ted A verage from the Rep ort Type drop-do wn list. Field Variable contains a list of the field v ariables tha t can b e used in the sur face integrations .This option is not ac tive if the Area,Mass F low R ate, or Volume F low R ate option is ac tive. Surfaces is a selec table list of sur faces. Area displa ys the r esult of the ar ea summa tion o ver all the selec ted sur faces.This lab el is visible when Area is active. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3728Task P age R eference GuideArea-W eigh ted A verage displa ys the r esult of the ar ea-w eigh ted a verage c omputa tion o ver all the selec ted sur faces.This lab el is visible when Area-W eigh ted A verage is ac tive. Average of F acet Values displa ys the r esult of the fac et-a veraged c omputa tion o ver all the selec ted sur faces.This lab el is visible when Facet A verage is ac tive. Minimum of F acet Values displa ys the minimum fac et value on all the selec ted sur faces.This lab el is visible when Facet M inimum is ac tive. Maximum of F acet Values displa ys the maximum fac et value on all the selec ted sur faces.This lab el is visible when Facet M aximum is ac tive. Flow R ate displa ys the r esult of the flo w rate computa tion o ver all the selec ted sur faces.This lab el is visible when Flow R ate is ac tive. Integral displa ys the r esult of the in tegral computa tion o ver all the selec ted sur faces.This lab el is visible when Integral is ac tive. Mass F low R ate displa ys the r esult of the mass flo w rate computa tion o ver all the selec ted sur faces.This lab el is visible when Mass F low R ate is ac tive. Mass-W eigh ted A verage displa ys the r esult of the mass-a veraged c omputa tion o ver all the selec ted sur faces.This lab el is visible when Mass-W eigh ted A verage is ac tive. Standar d D eviation displa ys the r esult of the standar d de viation c omputa tion o ver all the selec ted sur faces.This lab el is visible when Standar d D eviation is ac tive. Sum of F acet Values displa ys the r esult of the summa tion o ver all the selec ted sur faces.This lab el is visible when Sum is ac tive. Uniformit y Inde x M ass-W t. displa ys the mass-w eigh ted unif ormity inde x value on all the selec ted sur faces.This lab el is visible when Uniformit y Inde x - M ass Weigh ted is ac tive. Uniformit y Inde x Area-W t. displa ys the ar ea-w eigh ted unif ormity inde x value on all the selec ted sur faces.This lab el is visible when Uniformit y Inde x - A rea Weigh ted is ac tive. Average of S urface Vertex Values displa ys the r esult of the v ertex-averaged c omputa tion o ver all the selec ted sur faces.This lab el is visible when Vertex Average is ac tive. Minimum of Vertex Values displa ys the minimum fac et value on all the selec ted sur faces.This lab el is visible when Vertex M inimum is ac tive. 3729Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Reports Task P ageMaximum of Vertex Values displa ys the maximum fac et value on all the selec ted sur faces.This lab el is visible when Vertex M aximum is ac tive. Volumetr ic Flow R ate displa ys the r esult of the v olumetr ic flo w rate computa tion o ver all the selec ted sur faces.This lab el is visible when Volume F low R ate is ac tive. Highligh t Surfaces when enabled highligh ts the sur faces (selec ted in the Surface In tegrals dialo g box) in the gr aphics windo w. Save Output P aramet er... opens the Save Output P aramet er D ialog Box (p.3743 ). Comput e comput es the sp ecified in tegration on the selec ted sur faces. Write... opens The S elec t File D ialog Box (p.569), which y ou c an use t o sa ve the r eported v alues t o a file . 47.21.5. Volume In tegrals D ialo g Box The Volume In tegrals dialo g box allo ws you t o comput e the v olume , sum, maximum, minimum, volume in tegral, volume-a veraged quan tity, mass in tegral, or mass-a veraged quan tity of a sp ecified field v ariable on a selec ted list of c ell z ones . See Volume In tegration (p.2949 ) for details . Controls Rep ort Type contains option butt ons tha t control the metho d of v olume in tegration. Mass-A verage turns on the c omputa tion of the mass-a veraged quan tity on the c ell z one . Mass In tegral turns on the c omputa tion of the mass in tegral on the c ell z one . Mass turns on the c omputa tion of the t otal mass in the c ell z one f or the selec ted phase . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3730Task P age R eference GuideSum turns on the c omputa tion of the summa tion o ver all c ells in the selec ted z one . Sum*2P i comput es the summa tion o ver all c ells in the selec ted z one of a 2D axisymmetr ic mo del and multiplies the r esult b y 2π to giv e the summa tion o ver the r evolved domain. This option is only a vailable in 2D axisymmetr ic cases . Minimum comput es the minimum v alue of the selec ted v ariable a t each c ell in the selec ted z one . Maximum comput es the maximum v alue of the selec ted v ariable a t each c ell in the selec ted z one . Volume turns on the c omputa tion of the c ell z one v olume . Volume In tegral turns on the c omputa tion of the v olume in tegral on the c ell z one . Volume-A verage turns on the c omputa tion of the v olume-w eigh ted a verage on the c ell z one . Field Variable contains a list of the field v ariables tha t can b e used in the sum, volume in tegral, and a verage c omputa tions . This option is not ac tive if the Volume option is ac tive. Cell Z ones is a selec table list of c ell z ones . Total Volume displa ys the r esult of the v olume c omputa tion o ver all the selec ted z ones .This lab el is visible when Volume is ac tive. Sum displa ys the r esult of the summa tion o ver all the selec ted z ones .This lab el is visible when Sum is ac tive. Sum *2P i displa ys the r esult of the summa tion o ver all the selec ted z ones multiplied b y 2π. This lab el is visible when Sum*2P i is ac tive. Max displa ys the r esult of the maximum v alue of the selec ted z one(s). This lab el is visible when Maximum is active. Min displa ys the r esult of the minimum v alue of the selec ted z one(s). This lab el is visible when Minimum is active. Total Volume In tegral displa ys the r esult of the v olume-in tegral computa tion o ver all the selec ted z ones .This lab el is visible when Volume In tegral is ac tive. 3731Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Reports Task P ageVolume-W eigh ted A verage displa ys the r esult of the v olume-a veraged c omputa tion o ver all the selec ted z ones .This lab el is visible when Volume-A verage is ac tive. Total M ass-W eigh ted In tegral displa ys the r esult of the mass-in tegral computa tion o ver all the selec ted z ones .This lab el is visible when Mass In tegral is ac tive. Mass-W eigh ted A verage displa ys the r esult of the mass-a veraged c omputa tion o ver all the selec ted z ones .This lab el is visible when Mass-A verage is ac tive. Save Output P aramet er... opens the Save Output P aramet er D ialog Box (p.3743 ). Comput e comput es the sp ecified in tegration on the selec ted z ones . Write... opens The S elec t File D ialog Box (p.569), which y ou c an use t o sa ve the r eported v alues t o a file . 47.21.6. Sample Trajec tories D ialo g Box The Sample Trajec tories dialo g box allo ws the wr iting of par ticle sta tes (p osition, velocity, diamet er, temp erature, and mass flo w rate) at various b oundar ies and planes (lines in 2D). See Sampling of Tra- jectories (p.2054 ) for details ab out the it ems b elow. Controls Boundar ies lists b oundar ies tha t can b e chosen as the sur faces a t which samples will b e wr itten. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3732Task P age R eference GuideLines (in 2D) lists lines tha t can b e chosen as the sur faces a t which samples will b e wr itten. Planes (in 3D) lists planes tha t can b e chosen as the sur faces a t which samples will b e wr itten. Release F rom Injec tions lists injec tions fr om which the injec tion t o be tracked is chosen. Append F iles causes the r esults of multiple c alcula tions t o be app ended t o a single file . Accumula te Erosion/A ccretion R ates causes er osion and accr etion r ates to be accumula ted f or repeated tr ajec tory calcula tions . Sort Sample F iles causes the sample files t o be sor ted b y injec tion and par ticle ID f or st eady tracking or simula ted time (flow-time in the 13th column) f or unst eady tracking.The la tter is r equir ed if the sample file is t o be used as an unst eady injec tion file . User-D efined F unc tions allow control of the f ormat and the inf ormation wr itten for the sample output. Output contains a dr op-do wn list of a vailable user-defined func tions . Comput e causes the par ticles t o be tracked and their sta tus t o be wr itten t o files when the y enc oun ter selec ted surfaces.This butt on will not app ear f or unst eady par ticle tr acking. Start initia tes sampling f or unst eady par ticle tr acking.This butt on will r eplac e the Comput e butt on if y ou ar e performing unst eady par ticle tr acking. After you click it , it will change t o the Stop butt on. Click Stop to stop the sampling . (The lab el will change back t o Start.) 47.21.7. Trajec tory Sample Hist ograms D ialo g Box The Trajec tory Sample Hist ograms dialo g box allo ws the plotting of hist ograms fr om sample files created in the Sample Trajec tories D ialog Box (p.3732 ). See Hist ogram R eporting of S amples (p.2056 ) for details ab out the it ems b elow. 3733Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Reports Task P ageControls Options contains check butt ons f or hist ogram options . Auto Range toggles b etween aut oma tic and manual settings of the hist ogram r ange . Percent causes the plot t o indic ate the p ercent of par ticles . Deselec ting this will r esult in the ac tual numb er of par ticles b eing plott ed. Hist ogram M ode allows you t o displa y the hist ogram with or without bars . Weigh ting allows you t o apply a w eigh t to the da ta sample . Diamet er S tatistics allows you t o displa y a summar y of diamet er sta tistics f or a selec ted v ariable in the c onsole windo w. Correlation allows you t o cho ose c orrelations b etween ho w one par ticle v ariable dep ends on another par ticle variable . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3734Task P age R eference GuideCumula tive Curve allows you t o comput e a cumula tive distr ibution cur ve for a selec ted v ariable . (Variable^3) allows you t o plot the cumula tive mass distr ibution f or a c onstan t par ticle densit y using the par ticle diamet er. Hist ogram P aramet ers contains c ontrols f or hist ogram plotting . Divisions sets the numb er of “bins ” in the hist ogram. Min displa ys the minimum v alue of the v ariable selec ted in the Variable list. If Auto Range is off , you c an set the minimum b y typing a new v alue . Max displa ys the maximum v alue of the v ariable selec ted in the Fields list. If Auto Range is off , you c an set the maximum b y typing a new v alue . Axes... opens the Axes D ialog Box (p.3717 ), which allo ws you t o cust omiz e the hist ogram ax es. Curves... opens the Curves D ialog Box (p.3720 ), which allo ws you t o cust omiz e the cur ves used in the hist ogram. Sample lists the da ta samples tha t ha ve been r ead in. Variable lists the fields v ariables a vailable in the selec ted sample . Scale, No. of Bins is an inf ormational list tha t displa ys the sc aling and the numb er of bins f or each v ariable in the selec ted sample .This list is displa yed only if Data F ile Reduc tion is selec ted. Weigh t lists the w eigh ted fields v ariables a vailable in the selec ted sample . Correlation lists the sampled v ariables , allo wing y ou t o cho ose the c orrelation v ariable . Data F ile Reduc tion enables the r educ tion of injec tion da ta in the selec ted sample and e xpands the dialo g box to sho w inputs for Data Reduc tion S ettings F or S elec ted Variables and Data Reduc tion Options . For inf ormation about a vailable da ta reduc tion settings , see Data R educ tion of S amples (p.2059 ). Plot displa ys the hist ogram in the ac tive gr aphics windo w. Write... stores the hist ograms in an X Y-plot file f ormat 3735Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Reports Task P ageComput e updates the Min and Max values . Read ... opens The S elec t File D ialog Box (p.569), wher e you c an selec t a sample file t o be read. Reduc e... reduc es sample da ta in the selec ted sample . For mor e inf ormation, see Data R educ tion of S amples (p.2059 ). This butt on is a vailable only if Data F ile Reduc tion is selec ted. Delet e remo ves the sample selec ted in the Sample list. 47.21.8. Particle S ummar y Dialo g Box The Particle S ummar y dialo g box allo ws you t o report a summar y for par ticle injec tions . See Summar y Reporting of C urrent Particles (p.2061 ) for details ab out the it ems b elow. Controls Injec tions lists the par ticle injec tion(s) f or which y ou c an gener ate a summar y. Summar y prints the injec tion summar y in the c onsole windo w. 47.21.9. Heat Exchanger Rep ort Dialo g Box The Heat Exchanger Rep ort dialo g box allo ws you t o report a summar y for hea t exchangers . See Postpr ocessing f or the H eat Exchanger M odel (p.1606 ) for details ab out the it ems b elow. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3736Task P age R eference GuideControls Options lists the a vailable r eporting options f or the hea t exchanger . Comput ed H eat Rejec tion allows you t o report the hea t rejec tion c alcula ted fr om the hea t exchanger . Inlet Temp erature allows you t o report the inlet t emp erature for b oth the pr imar y and the auxiliar y hea t exchanger fluid . Outlet Temp erature allows you t o report the outlet t emp erature for b oth the pr imar y and the auxiliar y hea t exchanger fluid . Mass F low R ate allows you t o report the mass flo w rate for b oth the pr imar y and the auxiliar y hea t exchanger fluid . Specific H eat allows you t o report the sp ecific hea t for b oth the pr imar y and the auxiliar y hea t exchanger fluid . Result displa ys the r esults of the c alcula tions onc e the Comput e butt on is selec ted. Heat Exchanger displa ys a list of hea t exchanger fluid z ones Fluid Z one (not a vailable when Comput ed H eat Rejec tion option is selec ted.) allo ws you t o report quan tities f or either the pr imar y or auxiliar y fluid z ones . Comput e comput es the sp ecified quan tity on the selec ted z ones . Write... opens The S elec t File D ialog Box (p.569), which y ou c an use t o sa ve the r eported v alues t o a file . 3737Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Reports Task P age47.21.10. Paramet ers D ialo g Box The Paramet ers dialo g box allo ws you t o cr eate input par amet ers (in Scheme or user-defined func tion procedur es only) and output par amet ers, which allo w you t o compar e reporting v alues f or diff erent cases , or include r eporting v alues in the func tion minimiz ed b y the mesh mor pher/optimiz er. See Creating Output P aramet ers (p.2935 ) for details ab out the it ems b elow. Controls Input P aramet ers contains a list of e xisting input par amet ers. See Defining and Viewing P aramet ers (p.842) for details ab out creating input par amet ers. Edit... opens the Paramet er Expr ession D ialog Box (p.3742 ). Imp ortant When using ANSY S Fluen t in ANSY S Workbench, par amet ers ar e not editable , so the Edit... butt on b ecomes the View... butt on.This op ens the Paramet er Expr ession D ialog Box (p.3742 ) wher e the par amet er pr operties c an only b e view ed. For mor e inf ormation, see the separ ate ANSY S Fluen t in Workbench User’s Guide . Delet e remo ves the selec ted input par amet er fr om the list of Input P aramet ers. More contains a dr op-do wn list tha t allo ws mor e ad vanced use of input par amet ers. Available options include: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3738Task P age R eference GuideUse in Scheme P rocedur e opens the Use Input P aramet er in Scheme P rocedur e Dialog Box (p.3739 ). Use in UDF opens the Use Input P aramet er for UDF D ialog Box (p.3740 ). Output P aramet ers contains a list of e xisting output par amet ers. Create opens the Report Definitions D ialog Box (p.3906 ), allo wing y ou t o create additional output par amet ers based on r eport definitions . Edit... opens the dialo g box corresponding t o the selec ted it em in the Output P aramet ers list. More contains a dr op-do wn list c ontaining additional tasks tha t you c an p erform, including: Delet e remo ves the selec ted output par amet er fr om the list of Output P aramet ers. Rename allows you t o rename the selec ted output par amet er. Print to Console reports values t o the c onsole windo w. If you selec t multiple output par amet ers, then the output in- cludes v alues fr om multiple output par amet ers. Print All to Console outputs the v alues fr om all output par amet ers t o the c onsole windo w. Write... allows you t o store the output t o a file . A dialo g box is displa yed allo wing y ou t o pr ovide a file name . Write All... prompts y ou f or a file name and then wr ites the v alues f or all of the output par amet ers t o a file . Note ANSY S Fluen t aut oma tically cr eates gener ic default names f or new input and output par a- met ers (f or e xample ,parameter-1 ,parameter-2 ,parameter-3 , and so on) I f a paramet er is delet ed, the default name is not r eused . For e xample , if y ou ha ve parameter- 1,parameter-2 , and parameter-3 , then delet e parameter-2 and cr eate a new paramet er, the default name f or the new par amet er will b e parameter-4 . 47.21.11. Use Input P aramet er in Scheme P rocedur e Dialo g Box The Use Input P aramet er in Scheme P rocedur e dialo g box allo ws you t o use the input par amet er in a Scheme pr ocedur e. In tur n, this Scheme pr ocedur e can also use t ext user in terface (TUI) c ommands . For mor e inf ormation, see Working With A dvanced P aramet er Options (p.847). 3739Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Reports Task P ageControls Input P aramet er contains the name of an input par amet er. Selec t opens the Selec t Input P aramet er D ialog Box (p.3472 ) wher e an input par amet er can b e chosen. Scheme P rocedur e (S ingle Real A rgumen t) contains a pr ocedur e name (if alr eady defined using a Scheme file) or pr ocedur e body wr itten in the Scheme language using lambda .This pr ocedur e should r eceive one r eal ar gumen t. Define regist ers the selec ted input par amet er. Regist ered List contains a list of r egist ered input par amet ers. Delet e remo ves a selec ted r egist ered input par amet er fr om the list. Print prints details of the r egist ered input par amet ers. 47.21.12. Use Input P aramet er for UDF D ialo g Box The Use Input P aramet er f or UDF dialo g box allo ws you t o selec t the input par amet ers tha t can b e used inside a user-defined func tion (UDF) dur ing c alcula tions . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3740Task P age R eference GuideControls Input P aramet er contains the name of an input par amet er. Selec t opens the Selec t Input P aramet er D ialog Box (p.3472 ) wher e an input par amet er can b e chosen. Define regist ers the selec ted input par amet er. Regist ered List contains a list of r egist ered input par amet ers. Delet e remo ves a selec ted r egist ered input par amet er fr om the list. Print prints the ID of the r egist ered input par amet ers.The ID v alues ar e used t o acc ess the v alue of the par a- met er in the user-defined func tion. 47.21.13. Rename D ialo g Box The Rename dialo g box allo ws you t o change the name of the output par amet er tha t you cr eated. Controls 3741Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Reports Task P ageNew N ame contains the new name of the output par amet er. 47.21.14. Paramet er E xpression D ialo g Box The Paramet er E xpression dialo g box allo ws you t o cr eate input par amet ers, which c an b e used t o run a c ase and v ary the v alue of the input t o explor e ho w the r esults change . Controls Name contains the name of the input par amet er expression. Definition contains the cur rent value of the input par amet er. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3742Task P age R eference GuideUsed In indic ates the c ell z one or b oundar y condition wher e the input par amet er is cur rently used .The r elevant zone or b oundar y condition will b e displa yed af ter you cr eate an input par amet er. Imp ortant Input par amet er e xpressions must b e dir ectly defined as a c onstan t value including appr o- priate units; it ma y not r eference another e xpression. Note ANSY S Fluen t aut oma tically cr eates gener ic default names f or new input and output par a- met ers (f or e xample ,parameter_1 ,parameter_2 ,parameter_3 , and so on) I f a paramet er is delet ed, the default name is not r eused . For e xample , if y ou ha ve paramet- er_1 ,parameter_2 , and parameter_3 , then delet e parameter_2 and cr eate a new paramet er, the default name f or the new par amet er will b e parameter_4 . 47.21.15. Save Output P aramet er D ialo g Box The Save Output P aramet er dialo g box allo ws you t o sa ve sp ecific output par amet ers tha t allo w you to compar e reporting v alues f or diff erent cases . See Creating Output P aramet ers (p.2935 ) for details about the it ems b elow. Controls Options contains options f or sa ving y our output par amet ers. Create New Output P aramet er allows you t o create a new output par amet er. Apply Rep ort Settings t o an E xisting Output P aramet er allows you t o overwrite an e xisting output par amet er of the same t ype. 3743Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Reports Task P ageName contains the name f or the cur rent output par amet er. Note ANSY S Fluen t aut oma tically cr eates gener ic default names f or new input and output par a- met ers (f or e xample ,parameter-1 ,parameter-2 ,parameter-3 , and so on) I f a paramet er is delet ed, the default name is not r eused . For e xample , if y ou ha ve parameter- 1,parameter-2 , and parameter-3 , then delet e parameter-2 and cr eate a new paramet er, the default name f or the new par amet er will b e parameter-4 . 47.22. Paramet ers and C ustomiza tion Task P age The Paramet ers and C ustomiza tion task page in troduces y ou t o the par amet erization and cust omiza tion tools a vailable f or use in solving y our CFD simula tion using ANSY S Fluen t. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3744Task P age R eference GuideChapt er 48: Ribbon Ref erenc e Guide This r eference guide pr ovides inf ormation ab out the r ibbon in ANSY S Fluen t. 48.1. File R ibbon Tab 48.2. Dialog Boxes A vailable fr om the R ibbon 48.1. File R ibbon Tab For additional inf ormation, see the f ollowing sec tions: 48.1.1. File/R ead/M esh... 48.1.2. File/R ead/C ase... 48.1.3. File/R ead/D ata... 48.1.4. File/R ead/C ase & D ata... 48.1.5. File/R ead/PDF ... 48.1.6. File/R ead/ISA T Table ... 48.1.7. File/R ead/DTRM R ays... 48.1.8. File/R ead/V iew F actors... 48.1.9. File/R ead/P rofile ... 48.1.10. File/R ead/Scheme ... 48.1.11. File/R ead/J ournal... 48.1.12. File/W rite/Case... 48.1.13. File/W rite/Data... 48.1.14. File/W rite/Case & D ata... 48.1.15. File/W rite/PDF ... 48.1.16. File/W rite/ISA T Table ... 48.1.17. File/W rite/Flamelet... 48.1.18. File/W rite/Sur face Clusters... 48.1.19. File/W rite/Profile ... 48.1.20. File/W rite/Autosave... 48.1.21. File/W rite/Boundar y Mesh... 48.1.22. File/W rite/Start Journal... 48.1.23. File/W rite/Stop J ournal 48.1.24. File/W rite/Start Transcr ipt... 48.1.25. File/W rite/Stop Transcr ipt 48.1.26. File/Imp ort/AB AQUS/Input F ile... 48.1.27. File/Imp ort/AB AQUS/F ilbin F ile... 48.1.28. File/Imp ort/AB AQUS/ODB F ile... 48.1.29. File/Imp ort/CFX/D efinition F ile... 48.1.30. File/Imp ort/CFX/R esult F ile... 48.1.31. File/Imp ort/CGNS/M esh... 48.1.32. File/Imp ort/CGNS/D ata... 48.1.33. File/Imp ort/CGNS/M esh & D ata... 48.1.34. File/Imp ort/EnS ight... 48.1.35. File/Imp ort/FIDAP ... 48.1.36. File/Imp ort/GAMBIT ... 48.1.37. File/Imp ort/HYPERMESH ASCII... 3745Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.48.1.38. File/Imp ort/I-deas U niversal... 48.1.39. File/Imp ort/LST C/Input F ile... 48.1.40. File/Imp ort/LST C/State File... 48.1.41. File/Imp ort/Marc POST ... 48.1.42. File/Imp ort/Mechanic al APDL/Input F ile... 48.1.43. File/Imp ort/Mechanic al APDL/R esult F ile... 48.1.44. File/Imp ort/NASTR AN/B ulkda ta File... 48.1.45. File/Imp ort/NASTR AN/Op2 F ile... 48.1.46. File/Imp ort/PATRAN/N eutr al File... 48.1.47. File/Imp ort/PL OT3D/G rid File... 48.1.48. File/Imp ort/PL OT3D/R esult F ile... 48.1.49. File/Imp ort/PT C M echanic a Design... 48.1.50. File/Imp ort/Tecplot... 48.1.51. File/Imp ort/Fluen t 4 C ase F ile... 48.1.52. File/Imp ort/PreBFC F ile... 48.1.53. File/Imp ort/Partition/M etis... 48.1.54. File/Imp ort/Partition/M etis Z one ... 48.1.55. File/Imp ort/CHEMKIN M echanism... 48.1.56. File/Exp ort/Solution D ata... 48.1.57. File/Exp ort/Particle Hist ory Data... 48.1.58. File/Exp ort/During C alcula tion/S olution D ata... 48.1.59. File/Exp ort/During C alcula tion/P article Hist ory Data... 48.1.60. File/Exp ort to CFD-P ost... 48.1.61. File/S olution F iles... 48.1.62. File/In terpolate... 48.1.63. File/FSI M apping/V olume ... 48.1.64. File/FSI M apping/Sur face... 48.1.65. File/S ave Picture... 48.1.66. File/D ata File Q uantities ... 48.1.67. File/B atch Options ... 48.1.68. File/Exit 48.1.1. File/Read/M esh... The File/Read/M esh... ribbon tab it em op ens the Read M esh Options D ialog Box (p.3746 ), which allo ws you t o read or r eplac e a mesh. 48.1.1.1. Read Mesh O ptions D ialo g Box The Read M esh Options dialo g box is used t o read or r eplac e a mesh. See Reading M esh F iles (p.586) for mor e inf ormation. File → Read → Mesh... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3746Ribbon R eference GuideControls Options allows you t o read in a new mesh or r eplac e the e xisting mesh. Discard Case A nd D ata, Read N ew M esh results in b oth the c ase and da ta files b eing disc arded when r eading in a new mesh. Discard D ata, Replac e M esh results in the da ta file b eing disc arded when r eplacing an e xisting mesh. Show Sc ale M esh P anel A fter Replacing M esh gives y ou the option t o ha ve the Scale M esh D ialog Box (p.3238 ) app ear aut oma tically f or y ou t o check or sc ale y our mesh. 48.1.2. File/Read/C ase... The File/Read/C ase... ribbon tab it em is used t o read in an ANSY S Fluen t case file (e xtension .cas ), or a mesh file (e xtension .msh ,.grd ,.MSH , or .GRD ) tha t has b een sa ved in the na tive format for ANSY S Fluen t. See Reading M esh F iles (p.586) and Reading and Writing C ase and D ata Files (p.587) for details . The File/Read/C ase... ribbon tab it em op ens The S elec t File D ialog Box (p.569), which allo ws you t o selec t the appr opriate file t o be read. 3747Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.File R ibbon Tab48.1.3. File/Read/D ata... The File/Read/D ata... ribbon tab it em is used t o read in an ANSY S Fluen t da ta file (which has a .dat extension). This it em will not b e available un til you r ead in a c ase or mesh file . See Reading and Writing Data Files (p.589) for details . The File/Read/D ata... ribbon tab it em op ens The S elec t File D ialog Box (p.569), which allo ws you t o selec t the appr opriate file t o be read. 48.1.4. File/Read/C ase & D ata... The File/Read/C ase & D ata... ribbon tab it em is used t o read in an ANSY S Fluen t case file and the corresponding da ta file (f or e xample ,myfile.cas and myfile.dat ) together . See Reading and Writing C ase and D ata Files Together (p.589) for details . The File/Read/C ase & D ata... ribbon tab it em op ens The S elec t File D ialog Box (p.569), which allo ws you t o selec t the appr opriate files t o be read. Selec t the appr opriate case file , and the c orresponding data file (tha t is, the file ha ving the same name with a .dat extension) will also b e read in. 48.1.5. File/Read/PDF ... The File/Read/PDF ... ribbon tab it em is used t o read a PDF file (e xtension .pdf ) created b y ANSY S Fluen t for use with the non-pr emix ed or par tially pr emix ed c ombustion mo del. This it em is a vailable Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3748Ribbon R eference Guideonly when the non-pr emix ed or par tially pr emix ed c ombustion mo del has b een enabled . See Saving the L ook-U p Tables (p.1728 ) for details . 48.1.6. File/Read/ISA T Table ... The File/Read/ISA T Table ... ribbon tab it em is used t o read an ISA T table (e xtension .isat ) for use with the C omp osition PDF Transp ort mo del. This it em is a vailable only when the C omp osition PDF Transp ort mo del has b een enabled . See Using ISA T Efficien tly (p.1796 ) for details . 48.1.7. File/Read/DTRM R ays... The File/Read/DTRM R ays... ribbon tab it em is used t o read a r ay file (e xtension .ray ) created b y ANSY S Fluen t for use with the DTRM (r adia tion mo del). This it em is a vailable only when the DTRM has been enabled . See Writing and R eading the DTRM R ay File (p.1494 ) for details . 48.1.8. File/Read/Vie w Factors... The File/Read/Vie w F actors... ribbon tab it em is used t o read in a view fac tor file f or use with the surface-to-sur face (S2S) r adia tion mo del. This it em is a vailable only when the S2S mo del has b een en- abled . See Reading View F actors in to ANSY S Fluen t (p.1509 ) for details . 48.1.9. File/Read/P rofile ... The File/Read/P rofile ... ribbon tab it em op ens the Selec t File dialo g box for reading pr ofiles ( Reading Profile F iles (p.594)), It is used t o read a c ell z one or b oundar y condition pr ofile file (e xtension .prof ). A pr ofile file defines pr ofiles tha t can b e used t o sp ecify flo w conditions f or a c ell z one or a b oundar y. See Profiles (p.1051 ) for details . 48.1.10. File/Read/Scheme ... The File/Read/Scheme ... ribbon tab it em is used t o read in a Scheme sour ce file (e xtension .scm ). See Reading Scheme S ource Files (p.597) for details . 48.1.11. File/Read/J our nal... The File/Read/J our nal... ribbon tab it em is used t o read in a jour nal file (e xtension .jou ) containing a sequenc e of ANSY S Fluen t commands .You c an cr eate a jour nal file using the File/W rite/Jour nal... ribbon tab it em. See Creating and R eading J ournal F iles (p.597) for details . 48.1.12. File/W rite/Case... The File/W rite/Case... ribbon tab it em is used t o sa ve an ANSY S Fluen t case file . See Reading and Writing C ase F iles (p.588) for details . 3749Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.File R ibbon TabThe File/W rite/Case... ribbon tab it em op ens The S elec t File D ialog Box (p.569), which allo ws you t o save the file with a name of choic e.The dialo g box is similar t o the Selec t File dialo g box for reading files , except tha t it has an additional option f or wr iting binar y files . Imp ortant •When ANSY S Fluen t wr ites a c ase file , the .cas extension is added t o the file name sp ecified , unless the name alr eady ends with .cas . •You c an also wr ite a c ompr essed file b y app ending .gz or .Z to the file name . (See Reading and Writing C ompr essed F iles (p.583) for details ab out file c ompr ession.) 48.1.13. File/W rite/D ata... The File/W rite/D ata... ribbon tab it em is used t o sa ve an ANSY S Fluen t da ta file (which has a .dat extension). See Reading and Writing D ata Files (p.589) for details . Imp ortant •When ANSY S Fluen t wr ites a da ta file , the .dat extension is added t o the file name sp ecified , unless the name alr eady ends with .dat . •You c an c ompr ess da ta files b y app ending .gz or .Z to the file name (see Reading and Writing Compr essed F iles (p.583) for details ab out file c ompr ession). 48.1.14. File/W rite/Case & D ata... The File/W rite/Case & D ata... ribbon tab it em is used t o sa ve an ANSY S Fluen t case file and da ta file at the same time (f or e xample ,myfile.cas and myfile.dat ). See Reading and Writing C ase and Data Files Together (p.589) for details . Enter the name of the c ase file in the t ext en try box in the Selec t File dialo g box and the c orresponding data file (same file name , but with a .dat extension) will also b e wr itten. 48.1.15. File/W rite/PDF ... The File/W rite/PDF ... ribbon tab it em is used t o wr ite a PDF file af ter computing the lo ok-up tables using the non-pr emix ed or par tially pr emix ed c ombustion mo del in ANSY S Fluen t.This it em is a vailable only when the non-pr emix ed or par tially pr emix ed c ombustion mo del has b een enabled . See Saving the L ook-U p Tables (p.1728 ) for details . 48.1.16. File/W rite/ISA T Table ... The File/W rite/ISA T Table ... ribbon tab it em is used t o wr ite an ISA T table . See Using ISA T Effi- cien tly (p.1796 ) for details . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3750Ribbon R eference Guide48.1.17. File/W rite/Flamelet ... The File/W rite/Flamelet ... ribbon tab it em is used t o wr ite a flamelet file gener ated using the non- premix ed or par tially pr emix ed c ombustion mo del in ANSY S Fluen t.This it em is a vailable only when the non-pr emix ed or par tially pr emix ed c ombustion mo del has b een enabled . See The D iffusion Flamelet M odels Theor y in the Theor y Guide for details . 48.1.18. File/W rite/Surface Clust ers... The File/W rite/Surface Clust ers... ribbon tab it em is used t o set par amet ers r elated t o sur face clust ers and view fac tors f or the sur face-to-sur face radia tion mo del. It op ens the View F actors and C lustering Dialog Box (p.3273 ).The dialo g box tha t you op en using the File/W rite/Surface Clust ers... ribbon tab item is diff erent than the one op ened via the Settings ... butt on in the Radia tion M odel dialo g box, in tha t it sa ves the settings y ou sp ecify t o a file tha t can b e used t o calcula te the view fac tors outside of ANSY S Fluen t (see Computing View F actors Outside ANSY S Fluen t (p.1507 )).When y ou click OK,The Selec t File D ialog Box (p.569) will op en so tha t you c an sp ecify a name f or the file wher e ANSY S Flu- ent should sa ve the settings . 48.1.19. File/W rite/Profile ... The File/W rite/Profile ... ribbon tab it em op ens the Write Profile D ialog Box (p.3478 ). 48.1.20. File/W rite/Autosa ve... The File/W rite/A utosa ve... ribbon tab it em op ens the Autosave Dialog Box (p.3628 ). 48.1.21. File/W rite/Boundar y M esh... The File/W rite/Boundar y M esh... ribbon tab it em is used t o wr ite the b oundar y zones (sur face mesh) of the domain t o a file .You c an then r ead this file in to the meshing mo de of F luen t or GAMBIT t o produce an impr oved v olume mesh. See Writing a B oundar y Mesh (p.597) for details . 48.1.22. File/W rite/Start Jour nal... The File/W rite/Start Jour nal... ribbon tab it em is used t o star t the r ecording of subsequen t ANSY S Fluen t commands t o a jour nal file .You c an r ead this jour nal file back in to Fluen t later (using the File/Read/J our nal... ribbon tab it em) t o aut oma te the e xecution of the r ecorded c ommands . See Creating and R eading J ournal F iles (p.597) for details . 48.1.23. File/W rite/Stop J our nal The File/W rite/Stop J our nal ribbon tab it em r eplac es the File/W rite/Start Jour nal... ribbon tab it em after the r ecording of a jour nal file has b egun. The File/W rite/Stop J our nal ribbon tab it em is used to end the jour nal r ecording . See Creating and R eading J ournal F iles (p.597) for details . 48.1.24. File/W rite/Start Transcr ipt... The File/W rite/Start Transcr ipt... ribbon tab it em is used t o star t the r ecording of a tr anscr ipt file containing all input t o and output fr om F luen t. (You c annot r ead a tr anscr ipt file back in to Fluen t.) See Creating Transcr ipt F iles (p.601) for details . 3751Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.File R ibbon Tab48.1.25. File/W rite/Stop Transcr ipt The File/W rite/Stop Transcr ipt ribbon tab it em r eplac es the File/W rite/Start Transcr ipt... ribbon tab item af ter the r ecording of a tr anscr ipt file has b egun. The File/W rite/Stop Transcr ipt ribbon tab it em is used t o end the tr anscr ipt r ecording . See Creating Transcr ipt F iles (p.601) for details . 48.1.26. File/Imp ort/AB AQUS/Input F ile... The File/Imp ort/AB AQUS/Input F ile... ribbon tab it em is used t o imp ort an AB AQUS input file (e xtension .inp ), which c ontains the input descr iption of a finit e elemen t mo del f or the AB AQUS finit e elemen t program. See ABAQUS F iles (p.604) for details . 48.1.27. File/Imp ort/AB AQUS/F ilbin F ile... The File/Imp ort/AB AQUS/F ilbin F ile... ribbon tab it em is used t o imp ort an AB AQUS filbin file (e xtension .fil ), which c ontains the finit e elemen t mo del and r esults da ta. See ABAQUS F iles (p.604) for details . 48.1.28. File/Imp ort/AB AQUS/ODB F ile... The File/Imp ort/AB AQUS/ODB F ile... ribbon tab it em is used t o imp ort an AB AQUS ODB file with a .odb extension. See ABAQUS F iles (p.604) for details . 48.1.29. File/Imp ort/CFX/D efinition F ile... The File/Imp ort/CFX/D efinition F ile... ribbon tab it em is used t o imp ort a CFX definition file (e xtension .def ), which c ontains mesh inf ormation t o be read in to Fluen t. See CFX F iles (p.604) for details . 48.1.30. File/Imp ort/CFX/Result F ile... The File/Imp ort/CFX/Result F ile... ribbon tab it em is used t o imp ort a CFX r esult file (e xtension .res ). See CFX F iles (p.604) for details . 48.1.31. File/Imp ort/CGNS/M esh... The File/Imp ort/CGNS/M esh... ribbon tab it em is used t o read in a C GNS-f ormat mesh file (e xtension .cgns ). See Meshes and D ata in C GNS F ormat (p.605) for details . 48.1.32. File/Imp ort/CGNS/D ata... The File/Imp ort/CGNS/D ata... ribbon tab it em is used t o read in a C GNS-f ormat da ta file . See Meshes and D ata in C GNS F ormat (p.605) for details . 48.1.33. File/Imp ort/CGNS/M esh & D ata... The File/Imp ort/CGNS/M esh & D ata... ribbon tab it em is used t o read in a set of C GNS-f ormat mesh and da ta files . See Meshes and D ata in C GNS F ormat (p.605) for details . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3752Ribbon R eference Guide48.1.34. File/Imp ort/EnSight... The File/Imp ort/EnSight... ribbon tab it em is used t o imp ort EnS ight files (e xtension .encas or .case ). See EnSight Files (p.606) for details . 48.1.35. File/Imp ort/FIDAP ... The File/Imp ort/FIDAP ... ribbon tab it em is used t o imp ort an ANSY S FIDAP neutr al file (e xtension .FDNEUT or .unv ). See ANSY S FIDAP N eutr al Files (p.606) for details . 48.1.36. File/Imp ort/GAMBIT ... The File/Imp ort/GAMBIT ... ribbon tab it em is used t o read in a neutr al file fr om GAMBIT . See GAMBIT and G eoM esh M esh F iles (p.607) for details . 48.1.37. File/Imp ort/HYPERMESH ASCII... The File/Imp ort/HYPERMESH ASCII... ribbon tab it em is used t o imp ort a HYPERMESH ASCII file (extension .hm ,.hma , or .hmascii ). See HYPERMESH ASCII F iles (p.607) for details . 48.1.38. File/Imp ort/I-deas U niversal... The File/Imp ort/I-deas U niversal... ribbon tab it em is used t o imp ort an I-deas U niversal file , which contains mesh inf ormation and z one t ypes to be read in to Fluen t. See I-deas U niversal F iles (p.607) for details . 48.1.39. File/Imp ort/LST C/Input F ile... The File/Imp ort/LST C/Input F ile... ribbon tab it em is used t o imp ort an LST C input file (e xtension .k, .key , or .dyn ), which c ontains the input descr iption of a finit e elemen t mo del f or the LS-D YNA finit e elemen t program. See LSTC Files (p.607) for details . 48.1.40. File/Imp ort/LST C/State File... The File/Imp ort/LST C/State File... ribbon tab it em is used t o imp ort an LST C sta te file (e xtension .d3plot ), which c ontains c ontrol da ta, geometr y da ta, and sta te da ta. See LSTC Files (p.607) for details . 48.1.41. File/Imp ort/M arc POST ... The File/Imp ort/M arc POST ... ribbon tab it em is used t o imp ort a M arc POST file gener ated using the MSC M arc finit e elemen t program. See Marc POST F iles (p.608) for details 48.1.42. File/Imp ort/M echanic al APDL/Input F ile... The File/Imp ort/M echanic al APDL/Input F ile... ribbon tab it em is used t o imp ort a M echanic al AP- DL input file (e xtensions .ans ,neu ,.cdb , or .prep7 ), which c ontains mesh inf ormation t o be read into Fluen t. See Mechanic al APDL F iles (p.608) for details . 3753Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.File R ibbon Tab48.1.43. File/Imp ort/M echanic al APDL/Result F ile... The File/Imp ort/M echanic al APDL/Result F ile... ribbon tab it em is used t o imp ort a M echanic al AP- DL r esult file (e xtension .rst ,.rth , or .rmg ). See Mechanic al APDL F iles (p.608) for details . 48.1.44. File/Imp ort/NASTR AN/Bulkda ta F ile... The File/Imp ort/NASTR AN/Bulkda ta F ile... ribbon tab it em is used t o imp ort a NASTR AN B ulkda ta file (e xtension .nas ,.dat , or .bdf ), which c ontains mesh inf ormation t o be read in to Fluen t. See NASTR AN F iles (p.608) for details . 48.1.45. File/Imp ort/NASTR AN/Op2 F ile... The File/Imp ort/NASTR AN/Op2 F ile... ribbon tab it em is used t o imp ort a NASTR AN Op2 file (e xtension .op2 ), which is an output binar y da ta file c ontaining da ta used in the NASTR AN finit e elemen t program. See NASTR AN F iles (p.608) for details . 48.1.46. File/Imp ort/PATRAN/N eutr al File... The File/Imp ort/PATRAN/N eutr al F ile... ribbon tab it em is used t o read in a P ATRAN N eutr al file (e x- tension .neu ,.out , or .pat ) zoned b y named c omp onen ts (tha t is, with the no des plac ed in to zones based on gr oup name). The P ATRAN neutr al file c ontains mesh inf ormation t o be read in to Fluen t. See PATRAN N eutr al Files (p.609) for details . 48.1.47. File/Imp ort/PL OT3D/G rid F ile... The File/Imp ort/PL OT3D/G rid F ile... ribbon tab it em is used t o imp ort a PL OT3D gr id file (e xtension .g,.x,.xyz , or .grd ). See PLOT3D F iles (p.609) for details . 48.1.48. File/Imp ort/PL OT3D/Result F ile... The File/Imp ort/PL OT3D/Result F ile... ribbon tab it em s used t o imp ort a PL OT3D r esult file (e xtension .g,.x,.xyz , or .grd ). See PLOT3D F iles (p.609) for details . 48.1.49. File/Imp ort/PT C M echanic a Design... The File/Imp ort/PT C M echanic a D esign... ribbon tab it em is used t o imp ort a PT C M echanic a Design file (e xtension .neu ), which c ontains analy sis, mo del, and r esults da ta (only in binar y form). See PTC Mechanic a Design F iles (p.609) for details . 48.1.50. File/Imp ort/Tecplot ... The File/Imp ort/Tecplot ... ribbon tab it em is used t o read in a Tecplot binar y file . See Tecplot F iles (p.610) for details . 48.1.51. File/Imp ort/Fluen t 4 C ase F ile... The File/Imp ort/Fluen t 4 C ase F ile... ribbon tab it em is used t o read in a c ase file cr eated in FL UENT 4. See Fluen t 4 C ase F iles (p.610) for details . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3754Ribbon R eference Guide48.1.52. File/Imp ort/PreBFC F ile... The File/Imp ort/PreBFC F ile... ribbon tab it em is used t o read in a str uctured (quadr ilateral or he xa- hedr al) mesh tha t was cr eated using P reBFC. See PreBFC F iles (p.610) for details . 48.1.53. File/Imp ort/Partition/M etis ... The File/Imp ort/Partition/M etis ... ribbon tab it em is used t o par tition a mesh and then r ead it in to the par allel v ersion of ANSY S Fluen t. See Using the P artition F ilter (p.3089 ) for an e xplana tion of the difference between this it em and the File/Imp ort/Partition/M etis Z one ... ribbon tab it em. 48.1.54. File/Imp ort/Partition/M etis Z one ... The File/Imp ort/Partition/M etis Z one ... ribbon tab it em is used t o par tition each c ell z one in a mesh individually and then r ead the mesh in to the par allel v ersion of ANSY S Fluen t. See Using the P artition Filter (p.3089 ) for an e xplana tion of the diff erence between this it em and the File/Imp ort/Partition/M et- is... ribbon tab it em. 48.1.55. File/Imp ort/CHEMKIN M echanism... The File/Imp ort/CHEMKIN M echanism... ribbon tab it em op ens the Imp ort CHEMKIN F ormat Mech- anism D ialog Box (p.3755 ). 48.1.55.1. Imp ort CHEMKIN F ormat Mechanism D ialo g Box The Imp ort CHEMKIN F ormat Mechanism dialo g box is used t o imp ort a CHEMKIN-f ormat chemic al mechanism file in to ANSY S Fluen t. See Imp orting a Volumetr ic Kinetic M echanism in CHEMKIN Format (p.1624 ) for details .The dialo g box can b e acc essed either fr om the Species M odel D ialog Box (p.3294 ) or fr om the main menu: File → Imp ort → CHEMKIN M echanism... 3755Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.File R ibbon TabControls Material N ame specifies a name f or the ma terial. Gas-P hase contains inputs f or imp orting the gas-phase mechanism in CHEMKIN f ormat. Kinetics Input F ile specifies the name of the gas-phase file in CHEMKIN-f ormat. If the file is not in the cur rent working folder , include the full pa th to the f older wher e it is lo cated. Thermodynamic D atabase specifies ther modynamic pr operty da ta for sp ecies whose ther modynamic da ta ar e not sp ecified in the k inetics input file .You c an enable All contained in K inetics Input F iles to indic ate tha t the kinetics input file c ontains the ther modynamic da ta for all the sp ecies . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3756Ribbon R eference GuideTransp ort Property Data (Optional) (if Imp ort da tabase is enabled) allo ws you t o sp ecify tr ansp ort property da ta for sp ecies whose transp ort da ta ar e not sp ecified in the k inetics input file .You c an enable All contained in K inetics Input F iles to indic ate tha t the k inetics input file c ontains the tr ansp ort da ta for all the sp ecies . Imp ort Surface M echanism enables the imp orting of the sur face mechanism. Surface contains inputs f or imp orting the sur face mechanism. This gr oup b ox app ears only when the Imp ort Surface M echanism option is enabled . Kinetics Input F ile specifies the name of the sur face kinetics CHEMKIN-f ormat file . Thermodynamic D atabase specifies whether the ther modynamic da ta for the sur face-chemistr y sp ecies will b e included in the surface kinetics CHEMKIN-f ormat file (if All contained in K inetics Input F ile is enabled or in the ther modynamic da tabase file sp ecified in the Gas-P hase group b ox (if Same as 'G as-P hase' is en- abled). Note tha t if no ther modynamic da tabase file is sp ecified in the Gas-P hase group b ox, the ther modynamic da ta for all sur face-chemistr y sp ecies must b e included the sur face kinetics input file. Imp ort imp orts the sp ecified C hemk in reaction mechanism and ther mal files and sa ves the imp orted da ta in the F luen t case file . Note tha t carrying the or iginal input files along with the F luen t case file is not r equir ed. ANSY S Fluen t will aut oma tically r egener ate these files when needed (f or e xample , when using the CHEMKIN-CFD solv er). 48.1.56. File/E xport/Solution D ata... The File/E xport/Solution D ata... ribbon tab it em op ens the Export Dialog Box (p.3757 ). 48.1.56.1. Export Dialo g Box The Export dialo g box allo ws you t o wr ite da ta tha t can b e read b y other da ta visualiza tion and postpr ocessing t ools. See Exporting S olution D ata (p.611) for a c omplet e descr iption of the a vailable data formats and ho w to use the dialo g box. File → Export → Solution D ata... 3757Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.File R ibbon TabControls File Type contains a dr op-do wn list tha t controls the output file f ormat tha t will b e wr itten using the Write... butt on. ABAQUS allows you t o sp ecify the sur face(s) and optional loads , based on the k ind of finit e elemen t analy sis selec ted, to be exported t o an AB AQUS file (e xtension .inp ). ASCII allows you t o sp ecify the sur face(s), scalars , location in the c ell fr om which the v alues of sc alar func tions are to be tak en, and the delimit er separ ating the fields , to be exported t o an ASCII file . AVS allows you t o sp ecify the sc alars y ou w ant to wr ite to be exported t o an A VS file . CDA T for CFD-P ost & E nSight allows you t o sp ecify the c ell z ones , surfaces, quan tities , format (Binar y or ASCII ), and whether a case file is wr itten for da ta export.The .cdat file f ormat is c ompa tible with b oth CFD-P ost and En- Sight. CGNS allows you t o sp ecify the sc alars y ou w ant to wr ite and the lo cation fr om which the v alues of sc alar func tions ar e to be tak en, to be exported t o a C GNS file (e xtension .cgns ). Data E xplor er allows you t o sp ecify the sur face(s) and the sc alars y ou w ant to wr ite to be exported t o a D ata Ex- plor er file (e xtension .dx ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3758Ribbon R eference GuideEnSight Case G old allows you t o sp ecify the sc alars y ou w ant to wr ite, the c ell z ones , interior z one sur faces, and lo cation in the c ell fr om which the v alues of sc alar func tions ar e to be tak en, and the file f ormat, to be exported to an EnS ight file (e xtension .geo ,.vel ,.scl1 , or .encas ). FAST allows you t o sp ecify the sc alars y ou w ant to wr ite, to be exported as a gr id file (P lot3D f ormat), a velocity file , and a sc alar file .This option is a vailable only f or a tr iangular or t etrahedr al mesh. FAST S olution allows you t o export a single file c ontaining densit y, velocity, and t otal ener gy da ta.This option is available only f or a tr iangular or t etrahedr al mesh. Field view U nstr uctured allows you t o sp ecify the sc alars y ou w ant to wr ite and the c ell z ones or sur faces fr om which the values of sc alar func tions ar e to be tak en, to be exported t o a FIELD VIEW binar y file (e xtension .fvuns ) and a r egions file (e xtension .fvuns.fvreg ). Note You must deselec t all c ell z ones b efore you c an selec t an y sur faces. I-deas U niversal allows you t o sp ecify the sur face(s), scalars , and optional loads , based on the k ind of finit e elemen t analy sis selec ted, to be exported t o an I-deas U niversal file . Mechanic al APDL Input allows you t o sp ecify the sur face(s) and optional loads , based on the k ind of finit e elemen t analy sis selec ted, to be exported t o a M echanic al APDL Input file (e xtension .cdb ). NASTR AN allows you t o sp ecify the sur face(s), scalars , and optional loads , based on the k ind of finit e elemen t analy sis selec ted, to be exported t o a NASTR AN file (e xtension .bdf ). PATRAN allows you t o sp ecify the sur face(s), scalars , and optional loads , based on the k ind of finit e elemen t analy sis selec ted, to be exported t o a P ATRAN neutr al file (e xtension .out ). TAITherm allows you t o sp ecify the sur face(s) f or which y ou w ant to wr ite da ta and the metho d of wr iting the heat transf er coefficien t, to be exported t o a P ATRAN neutr al file (e xtension .neu ).This option is available only when the Energy Equa tion is enabled . Tecplot allows you t o sp ecify the sur face(s) and the sc alars y ou w ant to wr ite, to be exported t o a Tecplot file . Cell Z ones specifies the c ell z ones f or which da ta is t o be wr itten for a CFD-P ost c ompa tible , EnS ight, or FIELD VIEW file. Surfaces specifies the sur faces for which da ta is t o be wr itten for an AB AQUS, ASCII, Data Explor er, I-deas U niversal, Mechanic al APDL Input , NASTR AN, PATRAN, TAITherm, or Tecplot file . 3759Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.File R ibbon TabQuan tities specifies v alid func tions f or output. The a ttribut es of the list ar e mo dified based on the ac tive file t ype. The list ma y be a single-selec tion or a multiple-selec tion list or it ma y be disabled , dep ending on the selec ted File Type. Structural L oads contains optional str uctural loads tha t can b e wr itten t o AB AQUS, I-deas U niversal, Mechanic al APDL Input , NASTR AN, and P ATRAN files .This option is a vailable only when Structural analy sis is selec ted. Force enables f orce to be wr itten as a load f or a str uctural analy sis. Pressur e enables pr essur e to be wr itten as a load f or a str uctural analy sis. Temp erature enables t emp erature to be wr itten as a load f or a str uctural analy sis.This option is a vailable only when the Energy Equa tion is enabled . Thermal L oads contains optional ther mal loads tha t can b e wr itten t o AB AQUS, I-deas U niversal, Mechanic al APDL Input , NASTR AN, and P ATRAN files .This option is a vailable only when Thermal analy sis is selec ted. Temp erature enables t emp erature to be wr itten as a load f or a ther mal analy sis. Heat Flux enables hea t flux t o be wr itten as a load f or a ther mal analy sis. Heat Trans C oeff enables hea t transf er coefficien t to be wr itten as a load f or a ther mal analy sis. Location (f orASCII ,CGNS ,and EnSight Case G old formats) specifies the lo cation in the c ell fr om which the v alues of sc alar func tions ar e to be tak en. Node specifies tha t da ta values a t the no de p oints ar e to be exported. Cell C enter specifies tha t da ta values fr om the c ell c enters ar e to be exported. EnSight Parallel (Available only with F luen t in par allel) cr eates .encas files suitable f or use in EnS ight En terprise. Analy sis (f orABAQUS ,I-deas U niversal ,Mechanic al APDL Input ,NASTR AN,and PATRAN formats specifies the finit e elemen t analy sis in tended . Structural specifies str uctural analy sis and allo ws you t o selec t the Structural L oads to be wr itten. Thermal specifies ther mal analy sis and allo ws you t o selec t the Thermal L oads to be wr itten. Delimit er (f orASCII format only) specifies the delimit er used t o separ ate the da ta fields . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3760Ribbon R eference GuideComma specifies c omma as the delimit er separ ating the da ta fields . Spac e specifies spac e as the delimit er separ ating the da ta fields . Transien t (forEnSight Case G old only) contains options f or e xporting tr ansien t da ta. Transien t enables e xport of tr ansien t da ta. Separ ate Files f or E ach Timest ep enables wr iting separ ate files f or each timest ep. Append F requenc y specifies the fr equenc y for app ending the da ta dur ing the solution pr ocess. Imp ortant The Append F requenc y option is r eplac ed b y the Write Frequenc y option when Separ ate Files f or E ach Timest ep is enabled .You c an sp ecify the fr equenc y for writing the separ ate files . File N ame specifies the r oot name f or the files t o be sa ved. Format (forEnSight Case G old and CDA T for CFD-P ost & E nSight) specifies the file f ormat. Binar y specifies the file f ormat as binar y. ASCII specifies the file f ormat as ASCII. Heat Transf er C oefficien t (forTAIThermformat only) specifies the basis f or the hea t transf er coefficien t exported. Flux B ased specifies the flux based metho d for wr iting the hea t transf er coefficien t. Wall F unc tion specifies the w all func tion based metho d for wr iting the hea t transf er coefficien t. Write Case F ile (for CDA T for CFD-P ost & E nSight only) specifies whether or not a c ase file is wr itten with the .cdat file. Write... opens The S elec t File D ialog Box (p.569) for wr iting the sp ecified func tion(s) in the sp ecified f ormat. 3761Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.File R ibbon Tab48.1.57. File/E xport/Particle Hist ory Data... The File/E xport/Particle Hist ory Data... ribbon tab it em op ens the Export Particle Hist ory Data D ialog Box (p.3762 ). 48.1.57.1. Export Particle Hist ory Data D ialo g Box The Export Particle Hist ory Data dialo g box allo ws you t o export par ticle hist ory da ta as y our solution progresses . See Exporting S teady-State Particle Hist ory Data (p.625) for details . File → Export → Particle Hist ory Data... Controls Type specifies the t ype of the file y ou w ant to wr ite. CFD-P ost allows you t o wr ite the file in CFD-P ost par ticle tr acks f ormat, which c an b e read in CFD-P ost. FieldVie w allows you t o wr ite the file in FIELD VIEW format, which c an b e read in FIELD VIEW. EnSight allows you t o wr ite the file in EnSight format. Geometr y allows you t o wr ite the file in .ibl format, which c an b e read in GAMBIT (not a vailable when Un- stead y Particle Track ing is enabled in the Discr ete Phase dialo g box, which is op ened b y click ing Discr ete Phase ... in the Physics ribbon tab). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3762Ribbon R eference GuideInjec tions allows you t o selec t the r equir ed injec tion fr om the list of pr edefined injec tions . Quan tity contains the list of v ariables f or which y ou c an e xport the par ticle da ta. Skip allows you t o “thin ” or “sample ” the numb er of par ticles tha t are exported. Coarsen reduc es the e xported file siz e by reducing the numb er of p oints tha t are wr itten for a giv en tr ajec tory. This is only v alid f or st eady-sta te cases . Particle F ile N ame allows you t o sp ecify the file name/dir ectory for the e xported da ta, using the Browse... butt on. Encas F ile N ame is the file name y ou will sp ecify if y ou selec ted EnSight under Type. Use the Browse... butt on t o selec t the .encas file tha t was cr eated when y ou e xported the file with the File/E xport... ribbon tab option. Numb er of P article Time S teps app ears when y ou selec t EnSight under Type.The sp ecified numb er is the numb er of par ticle time- steps tha t are sa ved t o the .encas file. 48.1.58. File/E xport/During C alcula tion/S olution D ata... The File/E xport/During C alcula tion/S olution D ata... ribbon tab it em op ens the Automa tic Exp ort Dialog Box (p.3631 ) (transien t cases only). 48.1.59. File/E xport/During C alcula tion/P article Hist ory Data... The File/E xport/During C alcula tion/P article Hist ory Data... ribbon tab it em op ens the Automa tic Particle Hist ory Data Exp ort Dialog Box (p.3635 ) (transien t cases only). 48.1.60. File/E xport to CFD-P ost... The File/E xport to CFD-P ost... ribbon tab it em op ens the Export to CFD-P ost D ialog Box (p.3763 ). 48.1.60.1. Export to CFD-P ost D ialo g Box The Export to CFD-P ost dialo g box allo ws you t o selec t the quan tities tha t you w ould lik e to export to CFD-P ost. See Exporting t o ANSY S CFD-P ost (p.633) for details . File → Export to CFD-P ost... 3763Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.File R ibbon TabControls Selec t Quan tities contains a selec table list wher e you c an cho ose the quan tities t o export. Format allows you t o export the .cdat file in Binar y or ASCII format. Write Case F ile specifies whether or not a c ase file is wr itten with the .cdat file. Open CFD-P ost specifies tha t after the files ha ve been wr itten, a CFD-P ost session is op ened , with the c ase and .cdat files loaded . CFD-P ost will displa y the r esults . Write... opens the Selec t File dialo g box, wher e you c an sp ecify the name and lo cation of the e xported files . 48.1.61. File/S olution F iles... The File/S olution F iles ... ribbon tab it em op ens the Solution F iles D ialog Box (p.3764 ). 48.1.61.1. Solution F iles D ialo g Box The Solution F iles dialo g box allo ws you t o manage the files tha t were created thr ough the Autosave Dialog Box (p.3628 ). See Managing S olution F iles (p.635) for details . File → Solution F iles ... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3764Ribbon R eference GuideControls Solution F iles a t contains a selec table list wher e you c an cho ose the files t o read or delet e. Read mak es the selec ted file the cur rent file . Note tha t if mor e than one file is selec ted, the Read butt on is disabled .When an ear lier solution is made cur rent, the solution files tha t were gener ated f or a la ter it er- ation/time-st ep will b e remo ved fr om this list when the c alcula tion c ontinues . Delet e remo ves the selec ted solution files . File N ames ... allows you t o obtain inf ormation ab out the solution files and the pa th of the asso ciated files . Rec over M issing S olution... Recovers the la test c ase and da ta files fr om the sy stem f older (\dp0\FFF\Fluent\ for analy sis sy stem and \dp0\ FLU \Fluent\ for comp onen t system) and list them in the Solution F iles a t list. (This option is a vailable only in F luen t used under Workbench.) 48.1.62. File/In terpolate... The File/In terpolate... ribbon tab it em op ens the Interpolate Data D ialog Box (p.3765 ). 48.1.62.1. Interp olat e Data D ialo g Box The Interpolate D ata dialo g box allo ws you t o in terpolate solution da ta fr om one mesh t o another . See Mesh-t o-M esh S olution In terpolation (p.637) for details . File → Interpolate... 3765Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.File R ibbon TabControls Options contains the in terpolation options . Read and In terpolate allows you t o read and in terpolate solution da ta on to the cur rent mesh. Write Data allows you t o wr ite an in terpolation file f or the solution da ta to be interpolated on to another mesh. Cell Z ones is a list of c ell z ones tha t can b e selec ted. Binar y File allows you t o wr ite binar y interpolation files .This option is a vailable only when Write Data is selec ted under Options . Fields is a list of all a vailable da ta fields tha t can b e selec ted.This list is a vailable only when Write Data is se- lected under Options . Read ... opens The S elec t File D ialog Box (p.569), in which y ou c an sp ecify the file t o be read.This butt on is available only when the Read and In terpolate option is selec ted. Write... opens The S elec t File D ialog Box (p.569), in which y ou c an sp ecify a name f or the file t o be sa ved and then sa ve the file .This butt on r eplac es the Read ... butt on when the Write Data option is selec ted. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3766Ribbon R eference Guide48.1.63. File/FSI M apping/V olume ... The File/FSI M apping/V olume ... ribbon tab it em op ens the Volume FSI M apping D ialog Box (p.3767 ). 48.1.63.1. Volume FSI M apping D ialo g Box The Volume FSI M apping dialo g box allo ws you t o map c ell da ta for a giv en geometr y from an ANSY S Fluen t file on to a file with a diff erent mesh and f ormat. See Mapping D ata for F luid-S tructure In teraction (FSI) A pplic ations (p.640) for a c omplet e descr iption of ho w to use the dialo g box. File → FSI M apping → Volume ... Controls Input F ile contains par amet ers r elated t o the input file . Type contains the options f or the f ormat of the input mesh file . ABAQUS specifies tha t an AB AQUS file will b e used as the input mesh file (e xtension .inp ). I-deas specifies tha t an I-deas file will b e used as the input mesh file (e xtension .unv ). Mechanic al APDL specifies tha t a M echanic al APDL file will b e used as the input mesh file (e xtension .cdb or .neu ). 3767Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.File R ibbon TabNASTR AN specifies tha t a NASTR AN file will b e used as the input mesh file (e xtension .bdf ). PATRAN specifies tha t a P ATRAN file will b e used as the input mesh file (e xtension .neu ,.out , or .pat ). FEA F ile specifies the name of the input mesh file (see the Input F ile Type descr iptions f or asso ciated file extensions). If the file is not in the cur rent working f older , include the full pa th to the f older wher e it is lo cated. Browse... opens The S elec t File D ialog Box (p.569), which y ou c an use t o sp ecify the input mesh file inst ead of entering it in the Input F ile text-en try box. Length U nits specifies the unit of length used in the input file . Displa y Options allows you t o cho ose either the FEA M esh or the ANSY S Fluen t Mesh (or b oth). Analy sis contains the options f or the k ind of da ta to be mapp ed. Structural specifies tha t da ta fields r elevant for a str uctural analy sis will b e mapp ed. Thermal specifies tha t da ta fields r elevant for a ther mal analy sis will b e mapp ed. Structural L oads consists of a list of a vailable loads , including Force,Pressur e, and Temp erature. Fluen t Zones contains a list of a vailable c ell z ones fr om the cur rent ANSY S Fluen t file fr om which c ell da ta will b e mapp ed. Output F ile contains the options f or the f ormat of the file tha t will b e created fr om the input mesh file and the mapp ed da ta. Type contains the options f or the f ormat of the output mesh file . ABAQUS specifies tha t an AB AQUS file will b e used as the output mesh file (e xtension .inp ). I-deas specifies tha t an I-deas file will b e used as the output mesh file (e xtension .unv ). Mechanic al APDL specifies tha t a M echanic al APDL file will b e used as the output mesh file (e xtension .cdb ). NASTR AN specifies tha t a NASTR AN file will b e used as the output mesh file (e xtension .bdf ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3768Ribbon R eference GuidePATRAN specifies tha t a P ATRAN file will b e used as the output mesh file (e xtension .out ). File N ame specifies the name of the input mesh file (see the Output F ile descr iptions f or asso ciated file e xten- sions). If the file is not in the cur rent working f older , include the full pa th to the f older wher e it is located. Browse... opens The S elec t File D ialog Box (p.569), which y ou c an use t o sp ecify the input mesh file inst ead of entering it in the Input F ile text-en try box. Include FEA M esh includes additional FEA inf ormation lik e no de/elemen t inf ormation in the e xported output file . Temp erature Units specifies the unit of t emp erature when mapping t emp erature for a str uctural analy sis or an y variable for a ther mal analy sis. Read reads the input file in to memor y. Displa y displa ys the selec ted mesh in the gr aphics windo w. Write writes an output file in which the selec ted ANSY S Fluen t cell da ta is mapp ed on to the input mesh file . 48.1.64. File/FSI M apping/S urface... The File/FSI M apping/S urface... ribbon tab it em op ens the Surface FSI M apping D ialog Box (p.3769 ). 48.1.64.1. Surface FSI M apping D ialo g Box The Surface FSI M apping dialo g box allo ws you t o map fac e da ta for a giv en geometr y from an ANSY S Fluen t file t o a file with a diff erent mesh and f ormat. See Mapping D ata for F luid-S tructure Interaction (FSI) A pplic ations (p.640) for a c omplet e descr iption of ho w to use the dialo g box. File → FSI M apping → Surface... 3769Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.File R ibbon TabControls Input F ile contains par amet ers r elated t o the input file . Type contains the options f or the f ormat of the input mesh file . ABAQUS specifies tha t an AB AQUS file will b e used as the input mesh file (e xtension .inp ). I-deas specifies tha t an I-deas file will b e used as the input mesh file (e xtension .unv ). Mechanic al APDL specifies tha t a M echanic al APDL file will b e used as the input mesh file (e xtension .cdb or .neu ). NASTR AN specifies tha t a NASTR AN file will b e used as the input mesh file (e xtension .bdf ). PATRAN specifies tha t a P ATRAN file will b e used as the input mesh file (e xtension .neu ,.out , or .pat ). FEA F ile specifies the name of the input mesh file (see the Input F ile Type descr iptions f or asso ciated file extensions). If the file is not in the cur rent working f older , include the full pa th to the f older wher e it is lo cated. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3770Ribbon R eference GuideBrowse... opens The S elec t File D ialog Box (p.569), which y ou c an use t o sp ecify the input mesh file inst ead of entering it in the Input F ile text-en try box. Length U nits specifies the unit of length used in the input file . Displa y Options allows you t o cho ose either the FEA M esh or the ANSY S Fluen t Mesh (or b oth). Analy sis contains the options f or the k ind of da ta to be mapp ed. Structural specifies tha t da ta fields r elevant for a str uctural analy sis will b e mapp ed. Thermal specifies tha t da ta fields r elevant for a ther mal analy sis will b e mapp ed. Structural L oads consists of a list of a vailable loads , including Force,Pressur e, and Temp erature. Fluen t Zones contains a list of a vailable fac e zones fr om the cur rent ANSY S Fluen t file fr om which c ell da ta will b e mapp ed. Output F ile contains the options f or the f ormat of the file tha t will b e created fr om the input mesh file and the mapp ed da ta. Type contains the options f or the f ormat of the output mesh file . ABAQUS specifies tha t an AB AQUS file will b e used as the output mesh file (e xtension .inp ). I-deas specifies tha t an I-deas file will b e used as the output mesh file (e xtension .unv ). Mechanic al APDL specifies tha t a M echanic al APDL file will b e used as the output mesh file (e xtension .cdb ). NASTR AN specifies tha t a NASTR AN file will b e used as the output mesh file (e xtension .bdf ). PATRAN specifies tha t a P ATRAN file will b e used as the output mesh file (e xtension .out ). File N ame specifies the name of the input mesh file (see the Output F ile descr iptions f or asso ciated file e xten- sions). If the file is not in the cur rent working f older , include the full pa th to the f older wher e it is located. 3771Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.File R ibbon TabBrowse... opens The S elec t File D ialog Box (p.569), which y ou c an use t o sp ecify the input mesh file inst ead of entering it in the Input F ile text-en try box. Include FEA M esh includes additional FEA inf ormation lik e no de/elemen t inf ormation in the e xported output file . Temp erature Units specifies the unit of t emp erature when mapping t emp erature for a str uctural analy sis or an y variable for a ther mal analy sis. HTC Type specifies the means of c alcula ting the hea t transf er coefficien t. ref-t emp uses a t emp erature equal t o the r eference temp erature to calcula te the hea t transf er coefficien t. cell-t emp uses a t emp erature equal t o the t emp erature of the c ell adjac ent to the fac e to calcula te the heat transf er coefficien t. wall-func-h tc calcula tes using Equa tion 42.57 (p.3037 ). Note tha t this option has the same definition as the field v ariable Wall F unc . Heat Tran. Coef., as descr ibed in Alphab etical Listing of F ield Variables and Their D efinitions (p.2988 ). Read reads the input file in to memor y. Displa y displa ys the selec ted mesh in the gr aphics windo w. Write writes an output file in which the ANSY S Fluen t da ta has b een mapp ed t o the mesh of the input file . 48.1.65. File/S ave Picture... The File/S ave Picture... ribbon tab it em op ens the Save Picture Dialog Box (p.3676 ). 48.1.66. File/D ata F ile Q uan tities ... The File/D ata F ile Q uan tities ... ribbon tab it em op ens the Data File Q uan tities D ialog Box (p.3630 ). 48.1.67. File/B atch Options ... The File/B atch Options ... ribbon tab it em op ens the Batch Options D ialog Box (p.3772 ). 48.1.67.1. Batch O ptions D ialo g Box The Batch Options dialo g box allo ws you t o selec t options t o suppr ess in teractive dialo g boxes fr om ANSY S Fluen t while r unning a c ase in ba tch mo de. See Batch Ex ecution Options (p.57) in the Getting Started G uide for details . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3772Ribbon R eference GuideFile → Batch Options ... Controls Confir m F ile O verwrite determines whether ANSY S Fluen t confir ms a file o verwrite.This option is enabled b y default. Hide Q uestions allows you t o hide Question dialo g boxes.This option is disabled b y default. Exit on E rror allows you t o aut oma tically e xit fr om ba tch mo de when an er ror o ccurs .This option is disabled b y default. When r un in ba tch mo de thr ough the c ommand pr ompt or a jour nal file with Exit on E rror enabled , Fluen t will e xit under the f ollowing cir cumstanc es: •Normal r un t ermina tion up on r eaching the end of a jour nal (r etur n value 0) •Error retur ned dur ing scr ipted t ext command e xecution (r etur n value 1) •Unexpected input (wr ong t ype) to text command (r etur n value 1) •Licensing er ror (r etur n value 2) If an in valid t ext command is en tered, Fluen t will not e xit, but pr oceed t o the ne xt text input. Note that in Windo ws you must star t Fluent with the -wait command line option. 48.1.68. File/E xit The File/E xit ribbon tab it em is used t o exit fr om the cur rent solv er session. 48.2. Dialo g Boxes A vailable fr om the R ibbon The dialo g boxes descr ibed in this sec tion c an b e acc essed thr ough the r ibbon, from the tabs other than the File ribbon tab . 48.2.1. 1D S imula tion Libr ary Dialog Box 48.2.2. Activate Cell Z ones D ialog Box 48.2.3. Adaption C ontrols D ialog Box 48.2.4. Adaption D ispla y Options D ialog Box 3773Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbon48.2.5. Adjac ency Dialog Box 48.2.6. Anima tion D efinition D ialog Box 48.2.7. Anisotr opic A daption D ialog Box 48.2.8. Auto Create Options D ialog Box 48.2.9. Auto Partition M esh D ialog Box 48.2.10. Boundar y Adaption D ialog Box 48.2.11. Cell R egist er D ispla y Options D ialog Box 48.2.12. Compiled UDFs D ialog Box 48.2.13. Contours D ialog Box 48.2.14. Convergenc e Conditions D ialog Box 48.2.15. Create/Edit M esh In terfaces D ialog Box 48.2.16. Custom F ield F unction C alcula tor D ialog Box 48.2.17. Custom La ws Dialog Box 48.2.18. Deactivate Cell Z ones D ialog Box 48.2.19. Define C ontrol Points D ialog Box 48.2.20. Delete Cell Z ones D ialog Box 48.2.21. Displa y Options - A daption D ialog Box 48.2.22. DPM R eport Definition D ialog Box 48.2.23. DPM S ource Report Definition 48.2.24. Drag R eport Definition D ialog Box 48.2.25. DTRM G raphics D ialog Box 48.2.26. DTRM R ays Dialog Box 48.2.27. Edit M esh In terfaces D ialog Box 48.2.28. Edit R eport File D ialog Box 48.2.29. Edit R eport Plot D ialog Box 48.2.30. Execut e on D emand D ialog Box 48.2.31. Expr ession D ialog Box 48.2.32. Expr ession R eport Definition D ialog Box 48.2.33. Field F unction D efinitions D ialog Box 48.2.34. Flux R eport Definition D ialog Box 48.2.35. Force Report Definition D ialog Box 48.2.36. Fuse F ace Zones D ialog Box 48.2.37. Geometr y Based A daption C ontrols D ialog Box 48.2.38. Geometr y Based A daption D ialog Box 48.2.39. Gradien t Adaption D ialog Box 48.2.40. Imp ort Particle D ata D ialog Box 48.2.41. Impr int Sur face Dialog Box 48.2.42. Impr ove Mesh D ialog Box 48.2.43. Injec tions D ialog Box 48.2.44. Input Summar y Dialog Box 48.2.45. Interface Options D ialog Box 48.2.46. Interpreted UDFs D ialog Box 48.2.47. Iso-C lip D ialog Box 48.2.48. Iso-Sur face Dialog Box 48.2.49. Iso-V alue A daption D ialog Box 48.2.50. Lift Report Definition D ialog Box 48.2.51. Line/R ake Sur face Dialog Box 48.2.52. Manage A daption R egist ers D ialog Box 48.2.53. Merge Z ones D ialog Box 48.2.54. Mesh A daption C ontrols D ialog Box 48.2.55. Mesh In terfaces D ialog Box 48.2.56. Mesh M orpher/Optimiz er D ialog Box Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3774Ribbon R eference Guide48.2.57. Mixing P lanes D ialog Box 48.2.58. Momen t Report Definition D ialog Box 48.2.59. Motion S ettings D ialog Box 48.2.60. Multi E dit D ialog Box 48.2.61. New R eport File D ialog Box 48.2.62. New R eport Plot D ialog Box 48.2.63. Objec tive Function D efinition D ialog Box 48.2.64. Optimiza tion Hist ory Monit or D ialog Box 48.2.65. Parallel C onnec tivit y Dialog Box 48.2.66. Paramet er Bounds D ialog Box 48.2.67. Particle Tracks D ialog Box 48.2.68. Partition Sur face Dialog Box 48.2.69. Partitioning and L oad B alancing D ialog Box 48.2.70. Pathlines D ialog Box 48.2.71. Plane Sur face Dialog Box 48.2.72. Point Sur face Dialog Box 48.2.73. Quadr ic Sur face Dialog Box 48.2.74. Reduc ed Or der M odel D ialog Box 48.2.75. Reference Frame D ialog Box 48.2.76. Region A daption D ialog Box 48.2.77. Replac e Cell Z one D ialog Box 48.2.78. Report Definitions D ialog Box 48.2.79. Report File D efinitions D ialog Box 48.2.80. Report Plot D efinitions D ialog Box 48.2.81. Residual M onit ors D ialog Box 48.2.82. Rotate Mesh D ialog Box 48.2.83. S2S Inf ormation D ialog Box 48.2.84. Separ ate Cell Z ones D ialog Box 48.2.85. Separ ate Face Zones D ialog Box 48.2.86. Set Injec tion P roperties D ialog Box 48.2.87. Set M ultiple Injec tion P roperties D ialog Box 48.2.88. Shell C onduc tion La yers D ialog Box 48.2.89. Shell C onduc tion M anager D ialog Box 48.2.90. Structural Point Sur face Dialog Box 48.2.91. Sur face Meshes D ialog Box 48.2.92. Sur face Report Definition D ialog Box 48.2.93. Sur faces D ialog Box 48.2.94. Thread C ontrol D ialog Box 48.2.95. Transf orm Sur face Dialog Box 48.2.96. Transla te Mesh D ialog Box 48.2.97. Turbo 2D C ontours D ialog Box 48.2.98. Turbo Averaged C ontours D ialog Box 48.2.99. Turbo Averaged X Y Plot D ialog Box 48.2.100. Turbo Options D ialog Box 48.2.101. Turbo Report Dialog Box 48.2.102. Turbo Topology Dialog Box 48.2.103. UDF Libr ary Manager D ialog Box 48.2.104. User-D efined F an M odel D ialog Box 48.2.105. User-D efined F unction H ooks D ialog Box 48.2.106. User-D efined M emor y Dialog Box 48.2.107. User D efined R eport Definition D ialog Box 48.2.108. User-D efined Sc alars D ialog Box 3775Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbon48.2.109. Vectors D ialog Box 48.2.110. Volume A daption D ialog Box 48.2.111. Volume R eport Definition D ialog Box 48.2.112. Warning D ialog Box 48.2.113. Yplus/Ystar A daption D ialog Box 48.2.114. Zone Sur face Dialog Box 48.2.1. 1D S imula tion Libr ary Dialo g Box The 1D S imula tion Libr ary dialo g box allo ws you t o set par amet ers r elated t o coupling b etween ANSY S Fluen t and GT-PO WER or WAVE. See Coupling B oundar y Conditions with GT-PO WER (p.1070 ) or Coupling B oundar y Conditions with WAVE (p.1075 ) for details ab out the it ems b elow. User D efined → Model S pecific → 1D C oupling ... Controls 1D Libr ary specifies the t ype of libr ary to be used . (Currently only GTp ower and WAVE are available .) 1D Input F ile N ame specifies the name of the GT-PO WER or WAVE input file . Start starts up GT-PO WER or WAVE and gener ates ANSY S Fluen t user-defined func tions f or each b oundar y in the input file . Stop unlinks the shar ed libr ary. 48.2.2. Activate Cell Z ones D ialo g Box The Activate Cell Z ones dialo g box allo ws you t o ac tivate a single c ell z one or multiple z ones . See Activating Z ones (p.818) for details . Domain → Zones → Activate... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3776Ribbon R eference GuideControls Cell Z ones contains a list of c ell z ones fr om which y ou c an selec t the z one t o be ac tivated. Activate activates the selec ted c ell z ones . 48.2.3. Adaption C ontrols D ialo g Box The Adaption C ontrols dialo g box allo ws you t o sp ecify the r efinemen t and c oarsening cr iteria tha t Fluen t will use t o adapt y our mesh. Domain → Adapt → Refine / C oarsen... Controls Refinemen t Criterion the cr iterion tha t Fluen t uses t o det ermine when t o refine the mesh. This cr iterion c an b e based on c ell regist er values or an e xpression. Selec t the metho d using the dr op-do wn. 3777Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonCoarsening C riterion the cr iterion tha t Fluen t uses t o det ermine when t o coarsen the mesh. This cr iterion c an b e based on c ell regist er values or an e xpression. Selec t the metho d using the dr op-do wn. Maximum Refinemen t Level controls the numb er of le vels of r efinemen t used t o split c ells dur ing the adaption. Minimum C ell Volume restricts the siz e of the c ell tha t is c onsider ed f or refinemen t. Even if the c ell is mar ked f or refinemen t, it will not b e refined if its c ell v olume is less than this thr eshold v alue . Dynamic A daption enables aut oma tic adaption, wher eby Fluen t aut oma tically adapts the mesh based on the pr ovided settings while the solution is pr ogressing . Frequenc y (time-st ep | it eration) allows you t o sp ecify the numb er of it erations or time st eps b etween t wo consecutiv e aut oma tic mesh adaptions , dep ending on whether y ou ar e performing a st eady-sta te or time-dep enden t solution, and on which solv er you ar e using . Advanc ed C ontrols provides additional options f or ad vanced adaption c ontrol. Additional Refinemen t Layers allows you t o sp ecify additional c ell la yers f or refining the mesh. Cell Regist ers drop-do wn list allo wing y ou t o create new c ell regist ers and manage e xisting ones . List C riteria prints to the c onsole the numb er of c ells mar ked f or refinemen t, the numb er of c ells mar ked f or coarsening , and the numb er mar ked f or b oth op erations . Displa y Options opens the 48.2.4. Adaption D ispla y Options D ialo g Box The Adaption D ispla y Options dialo g box allo ws you t o cust omiz e the displa y of adaption or mask regist ers.This dialo g box is only a vailable if y ou ha ve used the f ollowing t ext command:mesh/ad- apt/revert-to-R19.2-user-interface ; not e tha t if y ou r evert the user in terface, you c annot undo it in the cur rent session, and some func tionalit y is no longer a vailable . Domain → Adapt → More → Displa y Options ... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3778Ribbon R eference GuideControls Options contains check butt ons tha t control the dr awing of the mesh and the t ype of gr aphic al tool used t o displa y flagged c ells. Draw M esh toggles the abilit y to dr aw the mesh with the adaption displa y.This c ommand op ens the Mesh D ispla y Dialog Box (p.3239 ), which allo ws you t o selec t the desir ed sur face or z one meshes t o be displa yed with the mar kings . Filled toggles the solid shading of the c ell wir eframe . Refine contains options r elated t o the displa y of c ells mar ked f or refinemen t. Wireframe toggles the displa y of the c ell wir eframe f or cells flagged f or refinemen t. Marker toggles the displa y of the c ell mar ker for cells flagged f or refinemen t. Color is a dr op-do wn list of c olors f or the wir eframe or mar ker for the c ells mar ked f or refinemen t. Size is a r eal numb er en try for the siz e of the r efine c ell mar ker. A symb ol of siz e 1.0 is 3.0% of the heigh t of the displa y scr een. Symb ol is a dr op-do wn list of symb ols tha t can b e used f or the r efine c ell mar ker. Coarsen contains options r elated t o the displa y of c ells mar ked f or refinemen t. Wireframe toggles the displa y of the c ell wir eframe f or cells flagged f or coarsening . 3779Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonMarker toggles the displa y of the c ell mar ker for cells flagged f or coarsening . Color is a dr op-do wn list of c olors f or the wir eframe or mar ker for the c ells mar ked f or coarsening . Size is a r eal numb er en try for the siz e of the c oarsen c ell mar ker. A symb ol of siz e 1.0 is 3.0% of the heigh t of the displa y scr een. Symb ol is a dr op-do wn list of symb ols tha t can b e used f or the c oarsen c ell mar ker. 48.2.5. Adjac enc y Dialo g Box The Adjac enc y dialo g box allo ws you t o iden tify, displa y, and r ename fac e zones based on their adja- cency to a selec ted c ell z one . See Managing A djac ent Zones (p.820) for details . Domain → Zones → Adjac enc y... Cell Z one(s) contains a list of the c ell z ones f or which y ou c an find adjac ent fac e zones . Adjac ent Face Zones contains a list of the fac e zones tha t are adjac ent to the selec ted c ell z ones . Options Multiple C ell Z ones allows you t o selec t multiple c ell z ones a t onc e.The z ones list ed in Adjac ent Face Zones will b e the union of all z ones adjac ent to the selec ted c ell z ones . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3780Ribbon R eference GuideRename F ace Zones allows you t o rename selec ted fac e zones based on adjac ency or z one t ype. Draw D efault M esh brings up the Mesh D ispla y Dialog Box (p.3239 ) wher e you c an sp ecify z ones of the mesh t o be perman- ently displa yed as y ou displa y or hide fac e zones fr om within the Adjac enc y dialo g box.This c an b e helpful in c ases wher e the mesh is v ery comple x. If this option is not enabled , only the z ones selec ted in Adjac ent Face Zones will b e displa yed when y ou click Displa y Face Zones . On S elec ted F ace Zones contains c ontrols f or renaming fac e zones tha t are selec ted in Adjac ent Face Zones . For details on the renaming metho ds, refer to Renaming Z ones U sing the A djac ency Dialog Box (p.821). Rename b y Adjac enc y renames the selec ted fac e zones inc orporating the name of the adjac ent cell z one and the fac e zone type. Rename t o D efault renames the selec ted fac e zones with default names based on the fac e zone t ype and , if nec essar y to avoid duplic ate names , the z one id . Rename b y Wildc ard renames the selec ted fac e zones based on a pa ttern ma tch str ing in the From field and a r eplac emen t string in the To field . Abbr eviate Types uses abbr eviations f or the z one t ypes when r enaming r ather than the full z one t ype text. Exclude C ustom N ames excludes fr om r enaming an y zones tha t do not ma tch a r ecogniz ed naming pa ttern.This c an b e useful t o pr event inad vertently r eplacing a meaning ful name . Displac e Face Zones displa ys the fac e zones selec ted in Adjac ent Face Zones . 48.2.6. Anima tion D efinition D ialo g Box The Anima tion D efinition dialo g box allo ws you t o sp ecify a gr aphics objec t tha t will b e captur ed during the solution c alcula tion so tha t it ma y be pla yed back as an anima tion dur ing p ostpr ocessing . Solution → Activities → Create → Solution A nima tions ... 3781Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonControls Name name of the anima tion definition. Rec ord af ter e very specifies the fr equenc y tha t images ar e captur ed dur ing the c alcula tion. You c an selec t whether the fr e- quenc y is Iteration ,Time S tep (transien t only) or Flow Time (transien t only) fr om the dr op-do wn. Storage Type drop-do wn list with the a vailable f ormats for st oring the anima tion images . In M emor y the image files asso ciated with the anima tion will lost when y ou e xit F luen t. PPM Image Fluen t will sa ve the anima tion images in PPM Image f ormat (.cxa ), which is 2D . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3782Ribbon R eference GuideHSF F ile Fluen t will sa ve the anima tion images in HSF file f ormat (.hsf ), which is 3D . Storage D irectory shows the lo cation wher e the anima tion images will b e stored if the Storage Type is set t o PPM Image or HSF F ile. Windo w ID indic ates the windo w wher e the solution anima tion images will b e displa yed when the solution is c alcu- lating . Anima tion View specifies the anima tion objec t orientation tha t will b e used when the anima tion images ar e captur e dur ing the c alcula tion. views dr op-do wn list with all of the defined view s. Preview displa ys the selec ted anima tion objec t in the gr aphics windo w sp ecified b y Windo w ID . Use A ctive saves the cur rent view in the ac tive gr aphics windo w and aut oma tically selec ts it f or use in the anim- ation definition. Anima tion O bjec t lists the defined gr aphics objec ts tha t ma y be selec ted f or anima tion. New O bjec t drop-do wn list allo wing y ou t o create new gr aphics objec ts for anima ting . •Mesh... opens the Mesh D ispla y Dialog Box (p.3239 ). •Contours ... opens the Contours D ialog Box (p.3790 ). •Vectors... opens the Vectors D ialog Box (p.3954 ). •Pathlines ... opens the Pathlines D ialog Box (p.3891 ). •Particle Tracks ... opens the Particle Tracks D ialog Box (p.3881 ). •Scene ... opens Figur e 40.26: The Sc ene D ialog Box (p.2812 ). •XY Plot... opens the Solution X Y Plot D ialog Box (p.3703 ). •Rep ort Plot... opens the New R eport Plot D ialog Box (p.3874 ). Edit O bjec t... allows you t o edit the selec ted gr aphics objec t. OK creates the anima tion definition and/or sa ves settings changes and closes the dialo g box. 3783Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbon48.2.7. Anisotr opic A daption D ialo g Box The Anisotr opic A daption dialo g box allo ws you t o perform anisotr opic adaption f or c ertain c ell t ypes. See Anisotr opic A daption (p.2721 ) for details . Domain → Adapt → More → Anisotr opic Refinemen t... Controls Cell Options controls the mar king of b oundar y layer cells. Cell D istanc e indic ates adaption using the distanc e of the mar ked c ell to the b oundar y zone . Regist er indic ates adaption using an e xisting r egist er. Splitting Options control ho w the splitting r atio is c omput ed. Automa tic allows the r atio t o be comput ed aut oma tically fr om the mesh. Manual allows you t o en ter a sp ecific v alue f or the r atio in the Split R atio field . Numb er of C ells indic ates the numb er of c ells t o be adapt ed and mar ked (a vailable only when the Cell D istanc e option is enabled). Split R atio allows you t o sp ecify a v alue f or the split r atio (a vailable only when the Manual splitting option is enabled). Regist ers provides a list of e xisting r egist ers (a vailable only when the Regist er option is enabled). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3784Ribbon R eference GuideBoundar y Zones contains a list of a vailable b oundar y zones . Refine refines the mar ked c ells. 48.2.8. Auto Create Options D ialo g Box The Auto Create Options dialo g box allo ws you t o define settings tha t you w ant applied t o the mesh interfaces tha t are created thr ough the aut oma tic metho d (for additional inf ormation, see Using a N on- Conformal M esh in ANSY S Fluen t (p.756)). It is op ened b y click ing the Options… butt on in the Unas- signed In terface Zones group b ox of the Mesh In terfaces D ialog Box (p.3852 ). Controls One t o One P airing specifies tha t the r esulting mesh in terfaces ha ve a single z one assigned t o each side . Using this option may decr ease y our c omputa tional e xpense and help with tr oublesho oting la ter on, though it ma y pr oduce a lar ger numb er of mesh in terfaces for y ou t o manage . Interface Options contains options r elated t o the in terface type. Mapp ed specifies tha t the mapp ed option is applied t o all of the r esulting in terfaces for which a t least one side of the in terface consists of only solid z ones . Note tha t the mapp ed option will b e applied r egar dless of the mesh qualit y, and the t oler ance used f or mapping will b e tha t specified in the Interface Options Dialog Box (p.3838 ). Static reduc es the memor y usage and pr ocessing time f or in terface creation (as w ell as f or solution), esp ecially when y ou ar e creating in terfaces using man y unassigned in terface zones .This option will only pr oduce correct results if the in terface zones do not mo ve or def orm relative to each other a t the in terfaces. 48.2.9. Auto Partition M esh D ialo g Box The Auto Partition M esh dialo g box allo ws you t o set the par amet ers f or aut oma tic par titioning when reading an unpar titioned mesh in to the par allel solv er. See Partitioning the M esh A utoma tically (p.3069 ) for details . 3785Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonParallel → Gener al → Auto Partition... Controls Metho d contains a dr op-do wn list of the r ecursiv e par tition metho ds tha t can b e used t o create the mesh par titions . The choic es include the Cartesian A xes,Cartesian S trip,Cartesian X-C oordina te,Cartesian Y-C oordin- ate,Cartesian Z-C oordina te,Cartesian R A xes,Cartesian R X-C oordina te,Cartesian R Y-C oordina te, Cartesian RZ-C oordina te,Cylindr ical A xes,Cylindr ical R-C oordina te,Cylindr ical Theta-C oordina te, Cylindr ical Z-C oordina te,Metis ,Polar A xes,Polar R-C oordina te,Polar Theta-C oordina te,Principal Axes,Principal S trip,Principal X-C oordina te,Principal Y-C oordina te,Principal Z-C oordina te, Spher ical A xes,Spher ical R ho-C oordina te,Spher ical Theta-C oordina te, and Spher ical P hi-C oordina te techniques , which ar e descr ibed in Mesh P artitioning M etho ds (p.3083 ). Case F ile allows you t o use a v alid e xisting par tition sec tion in a c ase file (tha t is, one wher e the numb er of par titions in the c ase file divides e venly in to the numb er of c omput e no des). You need t o tur n off the Case F ile option only if y ou w ant to change other par amet ers in the Auto Partition M esh dialo g box. Across Z ones allows par titions t o cross z one b oundar ies (the default). If tur ned off , it will r estrict par titioning t o within each c ell z one .This is r ecommended only when c ells in diff erent zones r equir e signific antly diff erent amoun ts of c omputa tion dur ing the solution phase , for e xample if the domain c ontains b oth solid and fluid z ones . Optimiza tions contains an option t o enable pr e-testing . Pre-Test instr ucts Fluen t to test all c oordina te dir ections and cho ose the one which yields the f ewest par tition interfaces for the final bisec tion. Note tha t this option is a vailable only when y ou cho ose Principal Axes or Cartesian A xes as the par titioning metho d. 48.2.10. Boundar y Adaption D ialo g Box The Boundar y Adaption dialo g box allo ws you t o mar k or r efine b oundar y cells on selec ted b oundar y zones .This dialo g box is only a vailable if y ou ha ve used the f ollowing t ext command:mesh/adapt/re- vert-to-R19.2-user-interface ; not e tha t if y ou r evert the user in terface, you c annot undo it in the cur rent session, and some func tionalit y is no longer a vailable . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3786Ribbon R eference GuideDomain → Adapt → Mark/A dapt C ells → Boundar y... Controls Options contains thr ee diff erent metho ds for b oundar y adaption: Cell D istanc e enables adaption based on a c ell’s distanc e from the b oundar y, measur ed in numb er of c ells. Normal D istanc e enables adaption based on a c ell’s nor mal distanc e from the b oundar y. Volume D istanc e enables adaption based on a tar get b oundar y volume and gr owth fac tor. Contours ... opens the Contours D ialog Box (p.3790 ), which y ou c an use t o det ermine the appr opriate par amet ers f or the b oundar y adaption. Manage ... opens the Manage A daption R egist ers D ialog Box (p.3848 ), which allo ws you t o displa y and manipula te adaption r egist ers tha t are gener ated using the Mark command . Controls... opens the Mesh A daption C ontrols D ialog Box (p.3851 ), which allo ws you t o control certain asp ects of the adaption pr ocess. Numb er of C ells sets the maximum b oundar y cell distanc e for adaption (used with the Cell D istanc e option. Distanc e Threshold sets the maximum nor mal distanc e for adaption (used with the Normal D istanc e option). 3787Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonBoundar y Volume sets the b oundar y volume in Equa tion 39.1 (p.2761 ) (used with the Volume D istanc e option). Growth F actor sets the e xponen tial gr owth fac tor in Equa tion 39.1 (p.2761 ) (used with the Volume D istanc e option). Boundar y Zones contains a selec table list of z ones on which y ou c an r efine .The b oundar y cells asso ciated with the z ones that you selec t will b e refined . Adapt refines the c ells with edges/fac es on the z ones selec ted in the Boundar y Zones list. Mark mar ks the b oundar y cells asso ciated with the z ones selec ted in the Boundar y Zones list f or refinemen t. This c ommand pr oduces an adaption r egist er. 48.2.11. Cell Regist er D ispla y Options D ialo g Box The Cell Regist er D ispla y Options dialo g box allo ws you t o cust omiz e the displa y of c ell r egist ers. You c an acc ess this dialo g box by click ing Displa y Options ... in an y of the c ell r egist er dialo g boxes. Controls Options contains check butt ons tha t control the dr awing of the mesh and the t ype of gr aphic al tool used t o displa y regist er cells. Draw M esh toggles the abilit y to dr aw the mesh with the c ell regist er displa y.This c ommand op ens the Mesh Displa y Dialog Box (p.3239 ), which allo ws you t o selec t the desir ed sur face or z one meshes t o be dis- played with the r egist er cells. Wireframe toggles the displa y of the c ell wir eframe . Filled toggles the solid shading of the c ell wir eframe . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3788Ribbon R eference GuideMarker toggles the displa y of the c ell mar ker. Color is a dr op-do wn list of c olors f or the wir eframe or mar ker for the c ells. Symb ol is a dr op-do wn list of symb ols tha t can b e used c ell mar ker. Size is a r eal numb er en try for the siz e of the c ell mar ker. A symb ol of siz e 1.0 is 3.0% of the heigh t of the displa y scr een. 48.2.12. Compiled UDFs D ialo g Box The Compiled UDFs dialo g box allo ws you t o op en a libr ary of c ompiled user-defined func tions . See the separ ate Fluen t Customiza tion M anual for details . User D efined → User D efined → Func tions → Compiled ... Controls Sour ce Files contains a list of sour ce files . Header F iles contains a list of header files . Add... opens the Selec t File dialo g box. Delet e delet es the selec ted file fr om the list. Libr ary Name specifies the name of the libr ary to be created. 3789Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonBuild builds the libr ary and c ompiles the user-defined func tion. Load opens the sp ecified libr ary and loads the user-defined func tion. 48.2.13. Contours D ialo g Box The Contours dialo g box controls the displa y of c ontour and pr ofile plots . See Displa ying C ontours and P rofiles (p.2784 ) for details ab out the it ems b elow. Results → Graphics → Contours → New... Controls Contour N ame is the name f or a c ontour plot definition. You c an sp ecify a name or use the default name contour- id. This c ontrol app ears only f or contour plot definitions . Options contains the check butt ons tha t set v arious c ontour displa y options . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3790Ribbon R eference GuideFilled toggles b etween filled c ontours and line c ontours . Node Values toggles b etween using sc alar field v alues a t no des and a t cell c enters f or computing the c ontours . When the Filled option is off ,Node Values is alw ays on. See Choosing N ode or C ell Values (p.2791 ) for details . Contour Lines combines filled c ontours with line c ontours .This option is only a vailable when b oth the Filled and Node Values options ar e enabled . Global R ange toggles b etween basing the minimum and maximum v alues on the r ange of v alues on the selec ted surfaces (off ), and basing them on the r ange of v alues in the en tire domain (on, the default). Auto Range toggles b etween aut oma tic and manual setting of the c ontour r ange . Any time y ou change the Contours of selec tion, Auto Range is reset t o on. Clip t o Range determines whether or not v alues outside the pr escr ibed Min/ Max range ar e contoured when using Filled contours . If selec ted, values outside the r ange will not b e contoured. If not selec ted, values below the Min value will b e color ed with the lo west c olor on the c olor sc ale, and v alues ab ove the Max value will b e color ed with the highest c olor on the c olor sc ale. See Specifying the R ange of Magnitudes D ispla yed (p.2789 ) for details . Draw P rofiles causes the addition of a pr ofile plot t o the c ontour plot. The Profile Options D ialog Box (p.3663 ) is opened when Draw P rofiles is selec ted. Draw M esh toggles b etween displa ying and not displa ying the mesh. The Mesh D ispla y Dialog Box (p.3239 ) is opened when Draw M esh is selec ted. Color ing specifies ho w the c ontours app ear. Banded the c ontour c olor ing f eatures distinc t color bands c orresponding t o the c olor map . Smooth the c ontours f eature a smo oth tr ansition b etween c olors . Color map Options ... opens the Color map D ialog Box (p.3697 ), allo wing y ou t o cust omiz e the c olor map f or this gr aphics objec t. Contours of contains a list fr om which y ou c an selec t the sc alar field t o be contoured. Min shows the minimum v alue of the sc alar field . If Auto Range is off , you c an set the minimum b y typing a new v alue . 3791Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonMax shows the maximum v alue of the sc alar field . If Auto Range is off , you c an set the maximum b y typing a new v alue . Surfaces contains a list fr om which y ou c an selec t the sur faces on which t o dr aw contours . For 2D c ases , if no sur face is selec ted, contouring is done on the en tire domain. For 3D c ases , you must alw ays selec t at least one surface. New S urface is a dr op-do wn list butt on tha t contains a list of sur face options: Point opens the Point Sur face Dialog Box (p.3898 ). Line/R ake opens the Line/R ake Sur face Dialog Box (p.3847 ). Plane opens the Plane Sur face Dialog Box (p.3895 ). Quadr ic opens the Quadr ic Sur face Dialog Box (p.3899 ). Iso-S urface opens the Iso-Sur face Dialog Box (p.3842 ). Iso-C lip opens the Iso-C lip D ialog Box (p.3841 ). Structural P oint opens the Structural Point Sur face Dialog Box (p.3928 ). Displa y draws the c ontours in the ac tive gr aphics windo w. Comput e calcula tes the sc alar field and up dates the Min and Max values (e ven when Auto Range is off ). Save/D ispla y plots the c ontour in the ac tive gr aphics windo w and sa ves the c ontour plot definition. This butt on app ears only f or contour plot definitions and r eplac es the Displa y butt on. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3792Ribbon R eference Guide48.2.14. Convergenc e Conditions D ialo g Box The c onvergenc e conditions facilit y allo ws you t o set c onvergenc e conditions on the solution based on the v alues fr om r eport definitions (sur face, volume , lift, drag, and so on). See Convergenc e Condi- tions (p.2657 ) for details on setting up the Convergenc e Conditions dialo g box. Note If you ar e solving a tr ansien t case, the Convergenc e Conditions dialo g box will r elab el some fields sinc e the tr ansien t case uses time-st eps r ather than it erations .These alt ernate labels ar e indic ated b elow. Solution → Rep orts → Conditions ... Controls Active check b ox for deac tivating/ac tivating individual c onvergenc e conditions . Conditions name of the c onvergenc e condition. Rep ort Definition name of the r eport definition used in judging c onvergenc e. Stop C riterion specifies the cr iterion b elow which the solution is c onsider ed t o be converged . Ignor e Iterations B efore | Ignor e Time S teps B efore ignor es the first f ew it erations/time-st eps if y ou e xpect the solution t o fluc tuate initially . 3793Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonUse Iterations | U se Time S teps specifies the numb er of pr evious it erations/time-st eps t o be included in the r eport definition c onver- genc e check. Check F or specify whether F luen t checks f or convergenc e at every time st ep or e very iteration. Solution C onvergenc e Fluen t checks f or solution c onvergenc e at every time st ep. Time S tep C onvergenc e Fluen t checks f or solution c onvergenc e at every iteration. Choose C ondition to selec t the c onvergenc e conditions . All Conditions ar e M et The solution is c onsider ed t o be converged if all of the c onvergenc e conditions ’ criteria ar e sa t- isfied , including those in the Residual M onit ors D ialog Box (p.3910 ). Any Condition is M et The solution is c onsider ed t o be converged if an y of the c onvergenc e conditions ’ criteria is sa tis- fied, including those in the Residual M onit ors D ialog Box (p.3910 ). Every Iteration | E very Time-S tep to selec t ho w of ten c onvergenc e checks ar e done . 48.2.15. Create/Edit M esh In terfaces D ialo g Box The Create/Edit M esh In terfaces dialo g box allo ws you t o manually cr eate mesh in terfaces for use with sliding meshes (see Using S liding M eshes (p.1257 )) or multiple r eference frames (see Mesh S etup for a M ultiple M oving R eference Frame (p.1240 )), or f or meshes with non-c onformal b oundar ies (see Non-C onformal M eshes (p.741)).This dialo g box requir es y ou t o decide which in terface zones mak e up b oth sides of each mesh in terface.While it is p ossible t o cr eate every type of mesh in terface using this dialo g box, it is only nec essar y when y ou w ant your in terface to use the p eriodic or p eriodic r epeats option; for all other t ypes it is mor e convenien t to aut oma tically cr eate in terfaces using the Mesh In- terfaces D ialog Box (p.3852 ), esp ecially when y ou ha ve man y interface zones and/or ar e unfamiliar with their names / lo cations . For details , see Using a N on-C onformal M esh in ANSY S Fluen t (p.756). The Create/Edit M esh In terfaces dialo g box is op ened b y click ing the Manual C reate... butt on in the Mesh In terfaces D ialog Box (p.3852 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3794Ribbon R eference GuideControls Mesh In terface contains a t ext en try box in which y ou c an set the name of the mesh in terface, and a list fr om which y ou can selec t an e xisting mesh in terface. Interface Zones S ide 1, Interface Zones S ide 2 contain selec table lists f or the in terface zones tha t mak e up the mesh in terface and inf ormational fields that sho w the names of the z ones y ou selec ted in each list. (You c annot edit the t op fields; the names in these fields will b e the names of the z ones y ou selec ted in the list b elow it.) Interface Options contains options r elated t o the in terface type. Periodic B oundar y Condition allows you t o create a non-c onformal p eriodic b oundar y condition in terface. Periodic Rep eats should b e enabled when each of the t wo cell z ones has a single pair of c onformal or non-c onformal periodics adjac ent to the in terface.This option is t ypic ally used in c onjunc tion with the sliding mesh model, when simula ting the in terface between a r otor and sta tor; it allo ws ANSY S Fluen t to treat the 3795Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibboninterface between the sliding and non-sliding z ones as p eriodic wher e the t wo zones do not o verlap. For details , see The P eriodic R epeats Option (p.745). Coupled Wall allows you t o sp ecify tha t the in terface ac ts as a ther mally c oupled w all. Matching is relevant if only in terface internal z ones should b e created (tha t is, interior or w all / shado w pairs), sinc e the in terface zones on b oth sides ar e aligned .With the Matching option, even in terface zones that are not p erfectly aligned ar e treated as if the y are; however, if the discr epanc y between the in ter- face zones on b oth sides e xceeds default thr esholds , then w arning messages will b e displa yed. Note that the Matching option is c ompa tible with the Periodic B oundar y Condition ,Coupled Wall, and Static options . For mor e inf ormation ab out the r ecommended uses of this option, see Matching Op- tion (p.748). Mapp ed enables an alt ernative appr oach f or mo deling c oupled w alls b etween z ones .This appr oach is mor e robust than the standar d non-c onformal in terface formula tions when the in terface zones penetr ate each other or ha ve gaps b etween them. It requir es tha t at least one side of the in- terface consists of only solid z ones . Note The Mapp ed option is not c ompa tible with shell c onduc tion. Static reduc es the memor y usage and pr ocessing time (f or in terface creation and solution), esp ecially when ther e ar e man y zones on b oth sides of the in terface.This option will only pr oduce correct results if the in terface zones do not mo ve or def orm relative to each other a t the in terface, and it is not c ompa tible with the Periodic B oundar y Condition ,Periodic Rep eats, or Mapp ed options . Non-O verlapping Z ones S ide 1, Non-O verlapping Z ones S ide 2 displa y the names of an y wall b oundar y zones cr eated b y ANSY S Fluen t dur ing the pr ocess of cr eating the selec ted mesh in terface. If the t wo interface zones o verlap each other c omplet ely, then the w all boundar ies ar e created but with z ero fac es. Interface Wall Z ones S ide 1, Interface Wall Z ones S ide 2 displa y the names of an y wall in terface zones cr eated b y ANSY S Fluen t dur ing the pr ocess of cr eating the selec ted mesh in terface. Interface In terior Z ones displa ys the names of an y interface interior z ones cr eated b y ANSY S Fluen t dur ing the pr ocess of cr eating the selec ted mesh in terface.This is used f or emb edded LES, when ther e is a need t o be able t o convert an in terior z one in to a R ANS-LES in terface. Periodic B oundar y Condition Type allows you t o selec t a p eriodicit y tha t is either Transla tional or Rota tional . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3796Ribbon R eference GuideOffset is the off set c oordina tes or angle , dep ending on whether Transla tional or Rota tional periodicit y is selec ted. Note tha t when Auto Comput e Offset is enabled , the Offset fields ar e not editable . Auto Comput e Offset will r esult in ANSY S Fluen t finding the off set. If this option is disabled , then y ou will ha ve to pr ovide the off set c oordina tes or angle in the r equir ed fields , dep ending on whether Transla tional or Rota- tional periodicit y is selec ted. Mapp ed Enable L ocal Toler anc e (when enabled) allo ws you t o overwrite an y value sp ecified in the Toler anc e group b ox in the Interface Options D ialog Box (p.3838 ), and is used on the selec ted in terface only . Local E dge L ength F actor (when enabled) allo ws you t o sp ecify the multiplier tha t Fluen t uses with the smallest edge length of the in terface zones t o calcula te the t oler ance for mapping . Disabling Local E dge L ength F actor allows you t o sp ecify an absolut e value f or the t oler ance. Create/Edit... performs one of the f ollowing: •If you ha ve en tered a new Mesh In terface name and selec ted unassigned z ones fr om the Interface Zones S ide 1 and Interface Zones S ide 2 selec tion lists , a new mesh in terface is cr eated. •If you ha ve made a selec tion fr om the Mesh In terface list, the Edit M esh In terfaces D ialog Box (p.3813 ) will op en so tha t you c an r evise the settings of e xisting mesh in terfaces. Delet e delet es the mesh in terface selec ted under Mesh In terface. Draw allows you t o displa y interface zones or mesh in terfaces in the gr aphics windo w. Note tha t you c an only selec t and displa y an in terface zone fr om Interface Zones S ide 1 or Interface Zones S ide 2 if it is not yet assigned t o an e xisting mesh in terface. After a Mesh In terface is cr eated, you c an selec t the appr opriate mesh in terface and click the Draw butt on t o displa y all of the z ones under Interface Zones S ide 1 and Interface Zones S ide 2 . List prints inf ormation ab out the selec ted Mesh In terface in the c onsole .When y ou click this butt on, ANSY S Fluen t will list the t wo interface boundar ies and (if y ou ha ve initializ ed the solution) all new z ones tha t were created (tha t is, wall and/or in terior z ones). 48.2.16. Custom F ield F unc tion C alcula tor D ialo g Box The Custom F ield F unc tion C alcula tor dialo g box allo ws you t o define cust om field func tions based on e xisting func tions , using simple c alcula tor op erators. Any func tions tha t you define will b e added to the list of default flo w variables and other field func tions pr ovided b y ANSY S Fluen t. Imp ortant Recall tha t you must en ter all c onstan ts in the func tion definition in SI units . 3797Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonSee Creating a C ustom F ield F unction (p.3039 ) for details ab out the it ems b elow. User D efined → Field F unc tions → Custom... Controls Definition displa ys the func tion tha t you ar e cur rently defining . As you selec t each it em fr om the Field F unc tions list or the c alcula tor k eypad , it will app ear in the Definition text en try box.You cannot edit the c ontents of this b ox dir ectly; if you w ant to delet e par t of a func tion, use the Delet e butt on on the k eypad . (Calcula tor Butt ons) are butt ons tha t perform calcula tor op erations .When y ou selec t a c alcula tor butt on (b y click ing on it), the appr opriate symb ol will app ear in the Definition text en try box. Selec t Op erand F ield F unc tions fr om contains the a vailable field func tions and the means f or selec ting them. Field F unc tions contains a list fr om which y ou c an selec t a v ariable t o be used in the definition of a new func tion. Selec t enters the v ariable tha t is cur rently selec ted in the Field F unc tions list in the Definition field . New Func tion N ame specifies the name of the func tion y ou ar e defining . Should y ou decide t o change the func tion name af ter you ha ve defined the func tion, you c an do so in the Field F unction D efinitions D ialog Box (p.3823 ), which you c an op en b y click ing on the Manage ... butt on. Define creates the func tion and adds it t o the list of Custom F ield F unc tions within the dr op-do wn list of available field func tions .The Define butt on is gr ayed out af ter you cr eate a new func tion or if the Definition field is empt y. Manage ... opens the Field F unction D efinitions D ialog Box (p.3823 ), which enables y ou t o check, rename , save, load , and delet e cust om field func tions . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3798Ribbon R eference Guide48.2.17. Custom L aws Dialo g Box The Custom L aws dialo g box is used t o inc orporate user-defined func tions (see the separ ate Fluen t Customiza tion M anual for details) in plac e of the default ph ysical la ws (1 thr ough 6) used in the heat/mass tr ansf er calcula tions . The Custom L aws dialo g box is op ened fr om the Set Injec tion P roperties D ialog Box (p.3917 ). Controls First L aw, Second L aw,Third Law, Four th L aw, Fifth L aw, Sixth L aw contain dr op-do wn lists in which y ou c an cho ose a user-defined par ticle la w to replac e the standar d law. Switching contains a dr op-do wn list in which y ou c an selec t a user-defined func tion tha t cust omiz es the w ay ANSY S Fluen t swit ches b etween par ticle la ws. 48.2.18. Deac tivate Cell Z ones D ialo g Box The Deac tivate Cell Z ones dialo g box allo ws you t o deac tivate a single c ell z one or multiple z ones . See Deactivating Z ones (p.817) for details . Domain → Zones → Deac tivate... 3799Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonControls Cell Z ones contains a list of c ell z ones fr om which y ou c an selec t the z one t o be deac tivated. Deac tivate deac tivates the selec ted c ell z ones . 48.2.19. Define C ontrol P oints D ialo g Box The Define C ontrol P oints dialo g box allo ws you t o cr eate, mo dify, and delet e control p oints for the mesh mor pher/optimiz er when the unstr uctured c ontrol p oint distr ibution is selec ted. See Using the Mesh M orpher/Optimiz er (p.3181 ) for details ab out using this dialo g box. The Define C ontrol P oints dialo g box is op ened fr om the Mesh M orpher/Optimiz er D ialog Box (p.3854 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3800Ribbon R eference GuideControls Control P oints lists the c ontrol p oints you ha ve created and allo ws you t o mo dify and delet e them. Definition Tools provides t ools f or defining the c ontrol p oints. Mouse-P robe allows you t o create control p oints by pr obing (using the r ight mouse butt on, by default) in the graphics windo w. Distribut e Throughout Z one allows you t o quick ly cr eate a numb er of c ontrol p oints and distr ibut e them on mesh no des throughout a sp ecific b oundar y zone . Zones allows you t o selec t the b oundar y zone thr oughout which y ou w ant to distr ibut e control p oints. 3801Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonAppr oxima te Numb er allows you t o sp ecify the appr oxima te numb er of c ontrol p oints you w ant to distr ibut e thr oughout a zone . Note tha t due t o the metho d by which the c ontrol p oints ar e distr ibut ed, the ac tual numb er ma y exceed the v alue y ou en ter. Distribut e creates a numb er of c ontrol p oints on mesh no des thr oughout the sp ecified z one (within the bounding b ox) with a distr ibution tha t is based on the distr ibution of the c ell fac es in tha t zone . Coordina tes allows you t o view and mo dify the c oordina tes of c ontrol p oints, as w ell as t o create new c ontrol points and t o delet e existing c ontrol p oints. X,Y,Z displa ys the c oordina tes of the selec ted Control P oint, and allo ws you t o define new ones and edit e xisting ones . Create creates a new c ontrol p oint at the cur rently displa yed X,Y, and Z coordina tes. Modify revises the X,Y, and Z coordina tes of the selec ted Control P oint. Delet e delet es the selec ted Control P oint. 48.2.20. Delet e Cell Z ones D ialo g Box The Delet e Cell Z ones dialo g box allo ws you t o delet e a single c ell z one or multiple z ones . See Deleting Zones (p.816) for details . Domain → Zones → Delet e... Controls Cell Z ones contains a list of c ell z ones fr om which y ou c an selec t the z one t o be delet ed. Delet e delet es the selec ted c ell z ones . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3802Ribbon R eference Guide48.2.21. Displa y Options - A daption D ialo g Box The Displa y Options - A daption dialo g box allo ws you t o cust omiz e ho w the c ells mar ked f or adaption are displa yed. This dialo g box is acc essed b y click ing Displa y Options in the Adaption C ontrols D ialog Box (p.3777 ). Controls Options contains check b oxes tha t controls the dr awing of the mesh. Draw M esh toggles the abilit y to dr aw the mesh with the adaption displa y.This c ommand op ens the Mesh D ispla y Dialog Box (p.3239 ), which allo ws you t o selec t the desir ed sur face or z one meshes t o be displa yed with the mar kings . Refinemen t Cells contains options r elated t o the displa y of c ells mar ked f or refinemen t. Faces controls whether c ell fac es ar e displa yed on the c ells mar ked f or refinemen t. Edges controls whether c ell edges ar e displa yed on the c ells mar ked f or refinemen t. Centroid controls whether the c ell c entroid is displa yed on the c ells mar ked f or refinemen t. Face Color controls the c olor of the c ell fac es on the c ells mar ked f or refinemen t. Edge C olor controls the c olor of the c ell edges on the c ells mar ked f or refinemen t. Edge Width controls the thick ness of the c ell edges on the c ells mar ked f or refinemen t. 3803Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonCoarsening C ells contains options r elated t o the displa y of c ells mar ked f or coarsening . Faces controls whether c ell fac es ar e displa yed on the c ells mar ked f or coarsening . Edges controls whether c ell edges ar e displa yed on the c ells mar ked f or coarsening . Centroid controls whether the c ell c entroid is displa yed on the c ells mar ked f or coarsening . Face Color controls the c olor of the c ell fac es on the c ells mar ked f or coarsening . Edge C olor controls the c olor of the c ell edges on the c ells mar ked f or coarsening . Edge Width controls the thick ness of the c ell edges on the c ells mar ked f or coarsening . Common C ells contains options r elated t o the displa y of c ells mar ked f or b oth r efinemen t and c oarsening . Faces controls whether c ell fac es ar e displa yed on the c ells mar ked f or b oth r efinemen t and c oarsening . Edges controls whether c ell edges ar e displa yed on the c ells mar ked f or b oth r efinemen t and c oarsening . Centroid controls whether the c ell c entroid is displa yed on the c ells mar ked f or b oth r efinemen t and c oarsening . Face Color controls the c olor of the c ell fac es on the c ells mar ked f or b oth r efinemen t and c oarsening . Edge C olor controls the c olor of the c ell edges on the c ells mar ked f or b oth r efinemen t and c oarsening . Edge Width controls the thick ness of the c ell edges on the c ells mar ked f or b oth r efinemen t and c oarsening . 48.2.22. DPM Rep ort Definition D ialo g Box Solution → Rep orts → Definitions → New → DPM Rep ort Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3804Ribbon R eference GuideControls Average O ver (optional) To ha ve Fluen t calcula te a r unning a verage f or the DPM Rep ort Definition you c an en ter a positiv e integer gr eater than 1 (the default) f or Average O ver. Specifying a numb er gr eater than 1 means that F luent will pr int, plot , and wr ite the r unning a verage value of the selec ted v ariable inst ead of the curr ent v alue of the same v ariable . The v alue r eported is a veraged o ver the last iterations/time st eps, wher e is y our sp ecified Average Over value .When the it eration/time st ep numb er is lo wer than , Fluent c alculat es the a verage of the available v ariable v alues . Rep ort Files lists all of the r eport files wher e you c an wr ite the r eport definition da ta. Rep ort Plots lists all of the r eport plots wher e you c an plot the r eport definition da ta (assuming this r eport has the same units as the other r eport definitions included in the selec ted r eport plot). 3805Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonCreate Rep ort File creates a new r eport file tha t includes this r eport definition. Rep ort Plot creates a new r eport plot tha t includes this r eport definition. Frequenc y specifies ho w fr equen tly the r eport definition is wr itten, plott ed, or pr inted t o the c onsole . Print to Console prints the v alue of the r eport definition t o the c onsole . Create Output P aramet er creates an output par amet er for this r eport definition with the name - op. Output Q uan tity Injec ted M ass (unst eady par ticle tr acking only) r eports the t otal DPM mass injec ted in to the domain. Mass in D omain (unst eady par ticle tr acking only) r eports the t otal DPM mass pr esen t in the domain. Mass in F luid (unst eady par ticle tr acking only) r eports all DPM mass cur rently r esiding as fr ee-str eam par ticles in the domain. This option is a vailable only with the wall-film DPM b oundar y condition. Mass in F ilm (unst eady par ticle tr acking only) r eports all DPM mass cur rently r esiding in Lagr angian w all-film. This option is a vailable only with the wall-film DPM b oundar y condition. Escaped M ass reports the DPM mass tha t has lef t the domain thr ough a c ertain b oundar y or b oundar ies. Evaporated M ass reports the t otal e vaporated DPM mass f or the selec ted injec tion(s). The quan tity acc oun ts for fully evaporated par ticles as w ell as all mass tha t has e vaporated fr om an y other par ticles . For unst eady tracking, this includes par ticles tha t are still pr esen t in the domain. Penetr ation L ength (unst eady par ticle tr acking only) r eports the t otal p enetr ation length in met ers. Injec tions lists the injec tions tha t you c an selec t for discr ete phase r eporting . For the Escaped M ass output quan tity, this it em is a vailable only if y ou ha ve enabled the report/dpm-zone-summaries-per-injection text command . Note tha t for unst eady par ticle tr acking, if you w ant to report the mass of esc aped par ticles per injec tion, this t ext command must b e enabled b efore an y par ticles ar e injec ted in to the domain. Boundar ies contains a selec table list of v alid b oundar y zones f or esc aped mass r eporting . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3806Ribbon R eference GuideShow M ass F low/C hange R ate (unst eady par ticle tr acking only) if enabled , specifies tha t the mass flo w rate will b e reported (default). Other wise the t otal mass will b e reported.This it em is not a vailable f or the Penetr ation L ength report. Particles M ass F raction the mass fr action e xpected b etween the injec tion no zzle and the p enetr ation length. This it em is a vailable only f or the Penetr ation L ength reports. User-S pecified Or igin and D irection once enabled , it allo ws you t o sp ecify the Origin and Direction of the selec ted injec tion(s). This it em is available only f or the Penetr ation L ength reports. OK creates the r eport definition. Comput e comput es the v alue of the r eport definition and pr ints to the c onsole . 48.2.23. DPM S our ce Rep ort Definition Solution → Rep orts → Definitions → New → Flux Rep ort → DPM M ass S our ce | DPM E nthalp y Sour ce | DPM S ensible E nthap y Sour ce Controls Func tion DPM M ass S our ce reports the mass c ontributions fr om the par ticle injec tions . DPM E nthalp y Sour ce reports the hea t contributions fr om the par ticle injec tions . 3807Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonDPM S ensible E nthalp y Sour ce reports the sensible hea t contributions fr om the par ticle injec tions . Average O ver (optional) To ha ve Fluen t calcula te a r unning a verage f or the DPM S our ce Rep ort Definition you c an enter a p ositiv e integer gr eater than 1 (the default) f or Average O ver. Specifying a numb er gr eater than 1 means that F luent will pr int, plot , and wr ite the r unning a verage value of the selec ted v ariable inst ead of the curr ent v alue of the same v ariable . The v alue r eported is a veraged o ver the last iterations/time st eps, wher e is y our sp ecified Average Over value .When the it eration/time st ep numb er is lo wer than , Fluent c alculat es the a verage of the available v ariable v alues . Rep ort Files lists all of the r eport files wher e you c an wr ite the r eport definition da ta. Rep ort Plots lists all of the r eport plots wher e you c an plot the r eport definition da ta (assuming this r eport has the same units as the other r eport definitions included in the selec ted r eport plot). Create Output P aramet er creates an output par amet er for this r eport definition with the name - op. Create Rep ort File creates a new r eport file tha t includes this r eport definition. Rep ort Plot creates a new r eport plot tha t includes this r eport definition. Frequenc y specifies ho w fr equen tly the r eport definition is wr itten, plott ed, or pr inted t o the c onsole . Print to Console prints the v alue of the r eport definition t o the c onsole . Comput e comput es the v alue of the r eport definition and pr ints to the c onsole . OK creates the r eport definition. 48.2.24. Drag Rep ort Definition D ialo g Box Solution → Rep orts → Definitions → New → Force Rep ort → Drag... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3808Ribbon R eference GuideControls Options Per Z one specifies whether or not the dr ag for multiple w alls z ones should b e monit ored on each w all z one separ ately.When this option is tur ned off (the default), Fluen t comput es and monit ors the t otal dr ag for all of the selec ted w alls z ones c ombined t ogether . Average O ver (Time-S teps), Average O ver (I terations) (optional) To ha ve Fluen t calcula te a r unning a verage f or the Drag Rep ort Definition you c an en ter a positiv e integer gr eater than 1 (the default) f or Average O ver. 3809Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonSpecifying a numb er gr eater than 1 means that F luent will pr int, plot , and wr ite the r unning a verage value of the selec ted v ariable inst ead of the curr ent v alue of the same v ariable . The v alue r eported is a veraged o ver the last iterations/time st eps, wher e is y our sp ecified Av- erage O ver value .When the it eration/time st ep numb er is lo wer than , Fluent c alculat es the a v- erage of the a vailable v ariable v alues . Force Vector contains the c omp onen ts of the f orce vector. X,Y,Z are the c omp onen ts of the f orce vector along which the f orces will b e comput ed. Rep ort Files lists all of the r eport files wher e you c an wr ite the r eport definition da ta. Rep ort Plots lists all of the r eport plots wher e you c an plot the r eport definition da ta (assuming this r eport has the same units as the other r eport definitions included in the selec ted r eport plot). Create Rep ort File creates a new r eport file tha t includes this r eport definition. Rep ort Plot creates a new r eport plot tha t includes this r eport definition. Frequenc y specifies ho w fr equen tly the r eport definition is wr itten, plott ed, or pr inted t o the c onsole . Print to Console prints the v alue of the r eport definition t o the c onsole . Create Output P aramet er creates an output par amet er for this r eport definition with the name - op. Rep ort Output Type Drag C oefficien t specifies the r eport definition as a unitless quan tity. Drag F orce specifies tha t the r eport definition has units of f orce. Wall Z ones lists the z ones y ou c an selec t for dr ag c oefficien t or dr ag force computa tion. OK creates the r eport definition. Comput e comput es the v alue of the r eport definition a t the selec ted z one(s) and pr ints to the c onsole . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3810Ribbon R eference Guide48.2.25. DTRM G raphics D ialo g Box The DTRM G raphics dialo g box allo ws you t o displa y rays and clust ers used b y the DTRM. See Displa ying Rays and C lusters f or the DTRM (p.1538 ) for details . Results → Model S pecific → DTRM G raphics ... Controls Displa y Type contains options f or the diff erent items y ou c an displa y. Clust er specifies the displa y of clust ers. Ray specifies the displa y of r ays. Options contains check butt ons tha t control displa y options . Draw M esh toggles b etween displa ying and not displa ying the mesh. The Mesh D ispla y Dialog Box (p.3239 ) is opened when Draw M esh is selec ted. Clust er Type specifies whether Surface clust ers or Volume clust ers ar e to be displa yed.This sec tion of the dialo g box app ears when Clust er is selec ted as the Displa y Type. 3811Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonClust er S elec tion contains options f or clust er displa ys.This sec tion of the dialo g box app ears when Clust er is selec ted as the Displa y Type. Displa y All Clust ers enables the displa y of all sur face or v olume clust ers in the domain. Ray Paramet ers contains c ontrols f or displa ying r ays.This sec tion of the dialo g box app ears when Ray is selec ted as the Displa y Type. Theta D ivisions , Phi D ivisions control the numb er of r ays being tr aced. (See Controlling the R ays (p.1494 ).) Nearest P oint specifies a p oint (X,Y,Z) near the clust er to be displa yed (or the clust er fr om which the r ays should star t). The Nearest P oint controls ar e not a vailable when Displa y All Clust ers is selec ted under Clust er Selec tion . Selec t Point With M ouse is an alt ernative metho d for sp ecifying the Nearest P oint using y our mouse , by click ing the butt on. Displa y displa ys the sp ecified clust er(s) or r ays. 48.2.26. DTRM R ays Dialo g Box The DTRM R ays dialo g box allo ws you t o define the r ays used b y the discr ete transf er radia tion model (DTRM). It op ens aut oma tically when y ou click OK after selec ting the Discr ete Transf er mo del in the Radia tion M odel D ialog Box (p.3269 ). See Setting U p the DTRM (p.1492 ) for details ab out the it ems below. Physics → Model S pecific → DTRM R ays... Controls Clust ering contains par amet ers f or the clust ers (see Clustering in the Theor y Guide ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3812Ribbon R eference GuideCells P er Volume C lust er, Faces P er S urface Clust er control the numb er of r adia ting sur faces and absorbing c ells. (See the e xplana tion in Controlling the Clusters (p.1493 ).) Angular D iscr etiza tion contains par amet ers f or the r ay traces (see Ray Tracing in the Theor y Guide ). Theta D ivisions , Phi D ivisions control the numb er of r ays being tr aced. (Guidelines ar e pr ovided in Controlling the R ays (p.1494 ).) Displa y Clust ers gener ates a gr aphic al displa y of the clust ers in the domain. (This it em is a vailable only af ter you ha ve created or r ead a r ay file .) 48.2.27. Edit M esh In terfaces D ialo g Box The Edit M esh In terfaces dialo g box allo ws you t o edit e xisting mesh in terfaces (see Using a N on- Conformal M esh in ANSY S Fluen t (p.756)). It is op ened b y mak ing a selec tion fr om the Mesh In terfaces list in the Mesh In terfaces D ialog Box (p.3852 ) and click ing Edit.... Controls Mesh In terfaces allows you t o selec t the mesh in terfaces y ou w ould lik e to edit. Note tha t you c an click the butt on to gr oup the in terfaces in the list b y their cur rently enabled in terface option(s), which allo ws you t o selec t / deselec t all those of a par ticular t ype by simply click ing the t op-le vel br anch. 3813Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonInterface Name edits the name of the mesh in terface.This is only a vailable when a single in terface is selec ted. Interface Options contains options r elated t o the in terface type.These options c an b e applied when a single or multiple interfaces ar e selec ted. Periodic B oundar y Condition allows you t o create a non-c onformal p eriodic b oundar y condition in terface. Periodic Rep eats should b e enabled when each of the t wo cell z ones has a single pair of c onformal or non-c onformal periodics adjac ent to the in terface.This option is t ypic ally used in c onjunc tion with the sliding mesh model, when simula ting the in terface between a r otor and sta tor; it allo ws ANSY S Fluen t to treat the interface between the sliding and non-sliding z ones as p eriodic wher e the t wo zones do not o verlap. For details , see The P eriodic R epeats Option (p.745). Coupled Wall allows you t o sp ecify tha t the in terface ac ts as a ther mally c oupled w all. Matching is relevant if only in terface internal z ones should b e created (tha t is, interior or w all / shado w pairs), sinc e the in terface zones on b oth sides ar e aligned .With the Matching option, even in terface zones that are not p erfectly aligned ar e treated as if the y are; however, if the discr epanc y between the in ter- face zones on b oth sides e xceeds default thr esholds , then w arning messages will b e displa yed. Note that the Matching option is c ompa tible with the Periodic B oundar y Condition ,Coupled Wall, and Static options . For mor e inf ormation ab out the r ecommended uses of this option, see Matching Op- tion (p.748). Mapp ed enables an alt ernative appr oach f or mo deling c oupled w alls b etween z ones .This appr oach is mor e robust than the standar d non-c onformal in terface formula tions when the in terface zones penetr ate each other or ha ve gaps b etween them. It requir es tha t at least one side of the in- terface consists of only solid z ones . Note The Mapp ed option is not c ompa tible with shell c onduc tion. Static reduc es the memor y usage and pr ocessing time (f or in terface creation and solution), esp ecially when ther e ar e man y zones on b oth sides of the in terface.This option will only pr oduce correct results if the in terface zones do not mo ve or def orm relative to each other a t the in terface, and it is not c ompa tible with the Periodic B oundar y Condition ,Periodic Rep eats, or Mapp ed options . Periodic B oundar y Conditions Type allows you t o selec t a p eriodicit y tha t is either Transla tional or Rota tional . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3814Ribbon R eference GuideOffset is the off set c oordina tes or angle , dep ending on whether Transla tional or Rota tional periodicit y is selec ted. Note tha t when Auto Comput e Offset is enabled , the Offset fields ar e not editable . Auto Comput e Offset will r esult in ANSY S Fluen t finding the off set. If this option is disabled , then y ou will ha ve to pr ovide the off set c oordina tes or angle in the r equir ed fields , dep ending on whether Transla tional or Rota- tional periodicit y is selec ted. Mapp ed Enable L ocal Toler anc e (when enabled) allo ws you t o overwrite an y value sp ecified in the Toler anc e group b ox in the Interface Options D ialog Box (p.3838 ), and is applied t o the selec ted in terface only . Local E dge L ength F actor (when enabled) allo ws you t o sp ecify the multiplier tha t Fluen t uses with the smallest edge length of the in terface zones t o calcula te the t oler ance for mapping . Disabling Local E dge L ength F actor allows you t o sp ecify an absolut e value f or the t oler ance. Interface Zones highligh ts the list of in terface zones tha t mak e up the selec ted mesh in terface and allo ws you t o edit the list (pr ovided tha t the z ones y ou selec t are unassigned and lo cated appr opriately). This func tionalit y is only a vailable when a single in terface is selec ted. List prints inf ormation in the c onsole ab out the first mesh in terface you selec ted.When y ou click this butt on, ANSY S Fluen t will list the t wo interface boundar ies and (if y ou ha ve initializ ed the solution) all new z ones that were created (tha t is, wall and/or in terior z ones). Apply saves the r evised settings f or the selec ted mesh in terfaces. 48.2.28. Edit Rep ort File D ialo g Box Solution → Rep orts → File... Selec t a r eport file in the Rep ort File D efinition dialo g box and click Edit... to op en the Edit Rep ort File dialo g box. 3815Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonControls Name editable field displa ying the name of the r eport file . Active check b ox (enabled b y default) tha t det ermines if the file is wr itten dur ing the solution c alcula tion. Available Rep ort Definitions lists all of the e xisting r eport definitions not cur rently par t of this r eport file . Add>> moves the selec ted r eport definition(s) t o the Selec ted Rep ort Definitions list. <> moves the selec ted r eport definition(s) t o the Selec ted Rep ort Definitions list. <- op. Comput e prints the v alue of the e xpression r eport definition t o the C onsole . Drop-do wns The it ems in these dr op-do wns ma y be used in cr eating e xpression r eport definitions . Func tions lists the a vailable func tions (c onditional, mathema tical, and so on) tha t are available f or constr ucting y our expression. Variables lists all of the supp orted v ariables . Cell Regist ers lists the defined c ell regist ers. Constan ts lists the a vailable pr e-defined c onstan ts. Expressions lists the defined e xpressions . Rep ort Definitions lists the defined r eport definitions . For additional inf ormation on e xpression r eport definitions , refer to Expr ession R eport Definition (p.2927 ). 48.2.33. Field F unc tion D efinitions D ialo g Box The Field F unc tion D efinitions dialo g box allo ws you t o check, rename , save, load , and delet e cust om field func tions tha t you defined in the Custom F ield F unction C alcula tor D ialog Box (p.3797 ). See Manip- ulating , Saving , and L oading C ustom F ield F unctions (p.3042 ) for details ab out the it ems b elow. The Field F unc tion D efinitions dialo g box is op ened fr om the Custom F ield F unction C alcula tor D ialog Box (p.3797 ). 3823Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonControls Definition displa ys the func tion selec ted in the Field F unc tions list. This displa y is f or inf ormational pur poses only ; you c annot edit it. Field F unc tions contains a selec table list of cust om field func tions .When y ou selec t a func tion, its definition will app ear in the Definition box and its name will app ear in the Name text en try box. Name displa ys the name of the cur rently selec ted field func tion. You c an en ter a new name in this b ox if y ou want to rename the func tion. ID reports the ID numb er of the selec ted func tion. The field func tion a t the t op of the list has an ID of 0, the second func tion has an ID of 1, and so on. Rename changes the name of the selec ted func tion t o the name sp ecified in the Name text en try box. Delet e delet es the selec ted field func tion. Save... opens The S elec t File D ialog Box (p.569), wher e you c an sp ecify a file in which t o sa ve all of the func tions in the Field F unc tions list. Load ... opens the Selec t File dialo g box, wher e you c an sp ecify a file fr om which t o read cust om field func tions (tha t is, a file tha t you sa ved using the Save... butt on ab ove). 48.2.34. Flux Rep ort Definition D ialo g Box Solution → Rep orts → Definitions → New → Flux Rep ort Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3824Ribbon R eference GuideControls Options Mass F low R ate turns on the c omputa tion of the mass flo w rate for the selec ted b oundar y zones . Total H eat Transf er R ate turns on the c omputa tion of the t otal hea t transf er rate for the selec ted b oundar y zones . Total S ensible H eat Transf er R ate turns on the c omputa tion of the t otal sensible hea t transf er rate for the selec ted b oundar y zones . It reports the t otal ener gy flux as defined in Equa tion 5.2 in the Theor y Guide . Radia tion H eat Transf er R ate turns on the c omputa tion of the r adia tion hea t transf er rate for the selec ted b oundar y zones . 3825Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonFilm M ass F low R ate (available only when the E uler ian w all film mo del is enabled) tur ns on the c omputa tion of the mass flow rate for the selec ted b oundar y zone(s). Film H eat Transf er R ate (available only when the E uler ian w all film mo del is enabled) tur ns on the c omputa tion of the film heat transf er rate for the selec ted b oundar y zone(s). Phase contains a list of all of the phases in the pr oblem tha t you ha ve defined .This is a vailable when the VOF, mixture, or E uler ian multiphase mo del is enabled . Per Z one specifies whether or not the chosen field v ariable is c alcula ted fr om all of the selec ted b oundar y zones combined (default) or individually on each of the selec ted b oundar y zones . Average O ver (Time-S teps), Average O ver (I terations) (optional) To ha ve Fluen t calcula te a r unning a verage f or the Flux Rep ort Definition you c an en ter a positiv e integer gr eater than 1 (the default) f or Average O ver. Specifying a numb er gr eater than 1 means that F luent will pr int, plot , and wr ite the r unning a verage value of the selec ted v ariable inst ead of the curr ent v alue of the same v ariable . The v alue r eported is a veraged o ver the last iterations/time st eps, wher e is y our sp ecified Average Over value .When the it eration/time st ep numb er is lo wer than , Fluent c alculat es the a verage of the available v ariable v alues . Rep ort Files lists all of the r eport files wher e you c an wr ite the r eport definition da ta. Rep ort Plots lists all of the r eport plots wher e you c an plot the r eport definition da ta (assuming this r eport has the same units as the other r eport definitions included in the selec ted r eport plot). Create Rep ort File creates a new r eport file tha t includes this r eport definition. Rep ort Plot creates a new r eport plot tha t includes this r eport definition. Frequenc y specifies ho w fr equen tly the r eport definition is wr itten, plott ed, or pr inted t o the c onsole . Print to Console prints the v alue of the r eport definition t o the c onsole . Create Output P aramet er creates an output par amet er for this r eport definition with the name - op. Rep ort Type selec ts the in tegration metho d used on the selec ted c ell z ones .The a vailable r eport types ar e the same as those in the Volume In tegrals D ialog Box (p.3730 ). See Volume In tegration (p.2949 ) for details . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3826Ribbon R eference GuideBoundar ies contains a selec table list of v alid b oundar y zones f or flux r eporting . OK creates the r eport definition. Comput e comput es the v alue of the r eport definition a t the selec ted z one(s) and pr ints to the c onsole . 48.2.35. Force Rep ort Definition D ialo g Box Solution → Rep orts → Definitions → New → Force Rep ort → Force... 3827Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonControls Options Per Z one specifies whether or not the f orce for multiple w alls z ones should b e monit ored on each w all z one separ ately.When this option is tur ned off (the default), Fluen t comput es and monit ors the t otal f orce for all of the selec ted w alls z ones c ombined t ogether . Average O ver (Time-S teps), Average O ver (I terations) (optional) To ha ve Fluen t calcula te a r unning a verage f or the Force Rep ort Definition you c an en ter a positiv e integer gr eater than 1 (the default) f or Average O ver. Specifying a numb er gr eater than 1 means that F luent will pr int, plot , and wr ite the r unning a verage value of the selec ted v ariable inst ead of the curr ent v alue of the same v ariable . The v alue r eported is a veraged o ver the last iterations/time st eps, wher e is y our sp ecified Av- erage O ver value .When the it eration/time st ep numb er is lo wer than , Fluent c alculat es the a v- erage of the a vailable v ariable v alues . Force Vector contains the c omp onen ts of the f orce vector. X,Y,Z are the c omp onen ts of the f orce vector along which the f orces will b e comput ed. Rep ort Files lists all of the r eport files wher e you c an wr ite the r eport definition da ta. Rep ort Plots lists all of the r eport plots wher e you c an plot the r eport definition da ta (assuming this r eport has the same units as the other r eport definitions included in the selec ted r eport plot). Create Rep ort File creates a new r eport file tha t includes this r eport definition. Rep ort Plot creates a new r eport plot tha t includes this r eport definition. Frequenc y specifies ho w fr equen tly the r eport definition is wr itten, plott ed, or pr inted t o the c onsole . Print to Console prints the v alue of the r eport definition t o the c onsole . Create Output P aramet er creates an output par amet er for this r eport definition with the name - op. Wall Z ones lists the z ones y ou c an selec t for force computa tion. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3828Ribbon R eference GuideOK creates the r eport definition. Comput e comput es the v alue of the r eport definition a t the selec ted z one(s) and pr ints to the c onsole . 48.2.36. Fuse F ace Zones D ialo g Box The Fuse F ace Zones dialo g box allo ws you t o fuse b oundar ies (tha t is, remo ve duplic ate no des and faces and delet e ar tificial in ternal b oundar ies) cr eated b y assembling multiple mesh r egions . (See Reading M ultiple M esh/C ase/D ata Files (p.733) for details on imp orting such meshes .) See Fusing F ace Zones (p.809) for inf ormation ab out using this dialo g box. Domain → Zones → Combine ... → Fuse ... Controls Zones contains a list of fac e zones fr om which y ou c an selec t the b oundar ies t o be fused . Use default name f or ne w fused z one specifies whether t o use an aut oma tically gener ated default name f or the fused z one . Fused z one name specifies the desir ed name f or the fused z one if Use default name f or ne w fused z one is disabled . Toler anc e is a fr action of the minimum edge length of the fac e, used t o det ermine whether or not no des ar e coin- ciden t. If all of the appr opriate fac es do not get fused using the default Toler anc e, you should incr ease it and a ttempt t o fuse the z ones again. The Toler anc e should not e xceed 0.5, or y ou ma y fuse the wr ong nodes. 3829Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonFuse fuses the selec ted z ones . It is enabled only when y ou ha ve selec ted a minimum of t wo zones . 48.2.37. Geometr y Based A daption C ontrols D ialo g Box The Geometr y Based A daption C ontrols dialo g box allo ws you t o set pr ojec tions . See Performing Geometr y-Based A daption (p.2724 ) for details ab out the it ems b elow. The Geometr y Based A daption C ontrols dialo g box is op ened fr om the Geometr y Based A daption Dialog Box (p.3830 ). Controls Controls contains par amet ers t o define geometr y based adaption. Disable G eometr y Based A daption f or this Z one disables the geometr y reconstr uction f or selec ted z ones in the domain. Levels of P rojec tion P ropaga tion is the numb er of la yers of the no des y ou w ant to pr ojec t. Direction of P rojec tion allows you t o sp ecify the dir ection in which y ou w ant to pr ojec t the no des. Back ground M esh allows you t o load the sur face mesh as a back ground mesh f or adaption. 48.2.38. Geometr y Based A daption D ialo g Box The Geometr y Based A daption dialo g box allo ws you t o reconstr uct the geometr y while p erforming boundar y adaption. See Geometr y-Based A daption (p.2723 ) for details . Domain → Adapt → More → Geometr y... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3830Ribbon R eference GuideControls Rec onstr uct Geometr y enables geometr y based adaption par amet ers. Surface M eshes ... opens the Surface Meshes D ialog Box (p.3929 ). Wall Z ones allows you t o selec t the w all z ones y ou w ant to adapt. Set... opens the Geometr y Based A daption C ontrols D ialog Box (p.3830 ). 48.2.39. Gradien t Adaption D ialo g Box The Gradien t Adaption dialo g box allo ws you t o mar k or adapt t o gr adien ts of a sp ecified field v ariable . This dialo g box is only a vailable if y ou ha ve used the f ollowing t ext command:mesh/adapt/revert- to-R19.2-user-interface ; not e tha t if y ou r evert the user in terface, you c annot undo it in the current session, and some func tionalit y is no longer a vailable . Domain → Adapt → Mark/A dapt C ells → Gradien t... 3831Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonControls Options contains the check butt ons tha t toggle the abilit y to mar k and/or adapt c ells f or refinemen t or c oarsening . Refine toggles the abilit y to refine or mar k cells f or refinemen t. Coarsen toggles the abilit y to coarsen or mar k cells f or coarsening (a vailable in 2D and axisymmetr ic cases). Normaliz e per Z one toggles the abilit y of z onal nor maliza tion. Contours ... opens the Contours D ialog Box (p.3790 ), which y ou c an use as an aid t o selec ting adaption thr esholds b y displa ying c ontours of adaption func tion. Manage ... opens the Manage A daption R egist ers D ialog Box (p.3848 ), which allo ws you t o displa y and manipula te adaption r egist ers tha t are gener ated using the Mark command . Controls... opens the Mesh A daption C ontrols D ialog Box (p.3851 ), which allo ws you t o control certain asp ects of the adaption pr ocess. Metho d contains options f or sp ecifying the cr iterion f or adaption. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3832Ribbon R eference GuideCurvature specifies the use of the sec ond gr adien t of a field v ariable f or adaption. This appr oach is r ecommended for pr oblems with smo oth solutions . Gradien t specifies the use of the first gr adien t of a field v ariable f or adaption. This appr oach is r ecommended for pr oblems with str ong sho cks. Iso-V alue allows you t o cust omiz e the adaption cr iterion (using cust om field func tions , user-defined sc alars , and so on). Normaliza tion contains the options a vailable f or nor maliza tion. Standar d specifies tha t the gr adien t or cur vature is not nor maliz ed. Scale specifies tha t the gr adien t or cur vature is sc aled b y its a verage v alue in the domain. Normaliz e specifies tha t the gr adien t or cur vature is sc aled b y its maximum v alue in the domain (tha t is, the gradien t or cur vature is b ounded b y [0, 1]). Dynamic contains options t o sp ecify d ynamic gr adien t adaption. Dynamic enables d ynamic gr adien t adaption. Interval allows you t o sp ecify the numb er of it erations or time-st eps b etween t wo consecutiv e aut oma tic mesh adaptions , dep ending on whether y ou ar e performing a st eady-sta te or a time-dep enden t solution, and on which solv er you ar e using . Gradien ts of contains a list of the field v ariables tha t can b e used in the gr adien t adaption func tion. Min/M ax displa ys the minimum and maximum c ell v alues of the gr adien t adaption func tion based on the selec ted quan tity. Coarsen Threshold designa tes the thr eshold v alues f or coarsening the mesh. Cells with adaption func tion v alues b elow the Coarsen Threshold will b e mar ked f or coarsening . Refine Threshold designa tes the thr eshold v alues f or refining the mesh. Cells with adaption func tion v alues ab ove the Refine Threshold will b e mar ked f or refinemen t. Adapt adapts the mesh based on the gr adien ts of the selec ted sc alar quan tity, the c oarsening and r efining toggle butt ons and thr esholds , and the adaption limits . 3833Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonMark mar ks cells t o be refined and/or c oarsened based on the gr adien ts of the selec ted quan tity and the coarsening and r efining t oggle butt ons and thr esholds .This c ommand pr oduces an adaption r egist er. Comput e comput es the minimum and maximum c ell v alues of the gr adien t adaption func tion with the selec ted scalar quan tity.The v alues ar e displa yed in the Min and Max real numb er fields . 48.2.40. Imp ort Particle D ata D ialo g Box The Imp ort Particle D ata dialo g box allo ws you t o imp ort par ticle hist ory da ta for displa y pur poses . See Imp orting P article D ata (p.2037 ) for details . Results → Model S pecific → Discr ete Phase → Imp ort Particle D ata... Controls Options contains the check butt ons tha t set v arious imp ort par ticle da ta options . Auto Range toggles b etween aut oma tic and manual setting of the par ticle da ta range . Draw M esh toggles b etween displa ying and not displa ying the mesh. The Mesh D ispla y Dialog Box (p.3239 ) is opened when Draw M esh is selec ted. Style allows you t o selec t pa thline st yle. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3834Ribbon R eference GuideAttribut es... opens the Path S tyle A ttribut es D ialog Box (p.3667 ).This allo ws you t o mo dify the line width, cylinder r adius or mar ker siz e. Color b y contains a list fr om which y ou c an selec t the sc alar field t o be used t o color the par ticle da ta. Min,M ax allows you t o set the r ange when Auto Range is disabled . Steps sets the maximum numb er of st eps a par ticle c an ad vance. Skip allows you t o “thin out ” the pa thlines . Displa y displa ys pa thlines . Pulse anima tes the par ticle p ositions .The Pulse butt on will b ecome the Stop ! butt on dur ing the anima tion, and y ou must click Stop ! to stop the pulsing . Read ... opens a file selec tion dialo g box wher e you c an en ter a file name and a dir ectory for the imp orted da ta. 48.2.41. Impr int Surface Dialo g Box The Impr int Surface dialo g box allo ws you t o define a sur face on t op of an e xisting c ell z one f or postpr ocessing pur poses . See Impr int Sur faces (p.2732 ) for details ab out the f ollowing it ems . Domain → Surface → Create → Impr int... 3835Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonControls Imp orted S urface lists the sur faces tha t you ha ve imp orted. Read ... opens The S elec t File D ialog Box (p.569), so tha t you c an selec t sur face files f or imp ort. Displa y allows you t o displa y the selec ted sur faces. Manage ... opens the Surfaces D ialog Box (p.3933 ), wher e you c an r ename and delet e sur faces and det ermine their siz es. New S urface Name designa tes the name of the new sur face.The default name f ormat is (imprint)- . From Z ones allows you t o selec t the z ones wher e you w ant to imp ort/impr int the sur face mesh. Note If no z one is selec ted, then the en tire domain is c onsider ed. Create creates the new sur face, impr inted with the mesh of the selec ted c ell z one . 48.2.42. Impr ove M esh D ialo g Box The Impr ove M esh dialo g box controls the qualit y-based smo othing of the numer ical mesh. See Im- proving the M esh b y Smoothing and S wapping (p.827) for details ab out the it ems b elow. Domain → Mesh → Impr ove... Controls Percentage of C ells t o be Impr oved sets the p ercentage of the t otal c ells on which impr ovemen ts ar e attempt ed. Note tha t the c ells selec ted for impr ovemen t are in the ar eas of the mesh tha t exhibit the lo west or thogonal qualit y. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3836Ribbon R eference GuideNumb er of I terations defines the numb er of succ essiv e smo othing sw eeps p erformed on the mesh. Impr ove initia tes the desir ed numb er of smo othing it erations . 48.2.43. Injec tions D ialo g Box The Injec tions dialo g box allo ws you t o cr eate, delet e, and list discr ete phase injec tions , and acc ess the Set Injec tion P roperties D ialog Box (p.3917 ) and the Set M ultiple Injec tion P roperties D ialog Box (p.3925 ), in which y ou c an set the pr operties f or the injec tions . See Creating and M odifying Injec- tions (p.1966 ) for details . Physics → Model S pecific → Discr ete Phase → Injec tions ... Controls Injec tions contains a list fr om which y ou c an selec t one or mor e injec tions in or der t o set , copy, or mo dify pr operties, or delet e or list injec tions . Create creates a new injec tion and op ens the Set Injec tion P roperties D ialog Box (p.3917 ), in which y ou c an set its pr operties. Copy creates a new injec tion with the same pr operties as the selec ted injec tion and op ens the Set Injec tion Properties D ialog Box (p.3917 ) wher e the new injec tion ’s properties c an b e mo dified . Delet e delet es the injec tion(s) selec ted in the Injec tions list. List lists the initial c onditions f or the par ticle str eams in the injec tion(s) selec ted in the Injec tions list. 3837Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonRead ... opens The S elec t File D ialog Box (p.569) wher e you will selec t the injec tion file t o read in. Write... allows you t o selec t the injec tion fr om the list and wr ite it t o a file . Set... opens the Set Injec tion P roperties D ialog Box (p.3917 ) for the injec tion selec ted in the Injec tions list or the Set M ultiple Injec tion P roperties D ialog Box (p.3925 ) if mor e than one injec tion is selec ted in the Injec- tions list. 48.2.44. Input S ummar y Dialo g Box The Input S ummar y dialo g box allo ws you t o report the cur rent settings f or ph ysical mo dels , boundar y conditions , ma terial pr operties, and solution par amet ers. See Gener ating a Summar y Report (p.2954 ) for details ab out the it ems b elow. Solution → Run C alcula tion → Input S ummar y... Controls Rep ort Options contains a selec table list of the inf ormation tha t is a vailable f or the r eport. Print prints the selec ted inf ormation t o the c onsole . Save... opens The S elec t File D ialog Box (p.569), in which y ou c an sp ecify the filename under which t o sa ve the output of the summar y report. 48.2.45. Interface Options D ialo g Box The Interface Options dialo g box allo ws you t o up date which mesh in terfaces use the mapp ed option and the r elated settings (see The M app ed Option (p.749) for additional inf ormation). It is op ened b y click ing the Options… butt on in the Mesh In terfaces group b ox of the Mesh In terfaces D ialog Box (p.3852 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3838Ribbon R eference GuideControls Mapp ed In terface contains options r elated t o mapp ed in terface sp ecific ation. Auto (Toler anc e-Based) specifies tha t all mesh in terfaces tha t ha ve in terface zones tha t penetr ate each other ar e automa tically defined as Mapp ed interfaces (pr ovided tha t at least one side of each in terface consists only of solid z ones). Toler anc e Local E dge L ength F actor (when enabled) allo ws you t o sp ecify the multiplier tha t Fluen t uses with the smallest edge length of the in terface zones t o calcula te the t oler ance for mapping . Disabling Local E dge Length F actor allo ws you t o sp ecify an absolut e value f or the t oler ance. Note tha t this do es not o verwrite an y locally sp ecified t oler ance in the Edit M esh In terfaces dialo g box. Solution C ontrols Mapping F requenc y specifies ho w of ten c alcula tion v alues ar e interpolated acr oss mapp ed in terfaces. Under-Relaxa tion F actor allows you t o reduc e the r ate of change p er it eration of ph ysical quan tities acr oss mapp ed in terfaces to aid with c onvergenc e. For additional inf ormation on setting under-r elaxa tion fac tors, see Setting Under-R elaxa tion F actors (p.2573 ). 3839Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonUpdate applies the selec tion(s) made in the Interface Options dialo g box.This butt on is gr ayed out un til you mak e a selec tion in the Mapp ed In terface or Toler anc e group b oxes; it also r etur ns to being gr ayed out once it is click ed. Note Selec ting Auto or Enforced and click ing Update applies these selec tions globally f or all relevant interfaces. Onc e you click Update you c an r etur n to the Mesh In terfaces dialo g box to mo dify lo cal settings f or individual in terfaces. 48.2.46. Interpreted UDFs D ialo g Box The Interpreted UDFs dialo g box allo ws you t o compile user-defined func tions . See the separ ate Fluen t Customiza tion M anual for details . User D efined → User D efined → Func tions → Interpreted... Controls Sour ce File N ame sets the name of y our user-defined func tion. CPP C ommand N ame sets the name of y our C pr eprocessor . Stack S ize sets the siz e of the stack. Keep the default Stack S ize setting of 10000, unless the numb er of lo cal variables in your func tion will c ause the stack t o overflow. In this c ase, set the Stack S ize to a numb er tha t is greater than the numb er of lo cal variables used . Displa y Assembly Listing indic ates whether or not t o displa y a listing of assembly language c ode in y our c onsole windo w as the func tion c ompiles . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3840Ribbon R eference GuideUse C ontribut ed CPP specifies the use of the C pr eprocessor tha t ANSY S Fluen t has supplied , inst ead of y our o wn. Interpret interprets the sp ecified func tion. 48.2.47. Iso-C lip D ialo g Box The Iso-C lip dialo g box allo ws you t o in teractively clip sur faces.The clipp ed sur face consists of those points on the selec ted sur face wher e the sc alar field v alues ar e within the sp ecified r ange . See Clipping Surfaces (p.2750 ) for details ab out the it ems b elow. Controls Clip t o Values of contains a list fr om which y ou c an selec t the sc alar field t o be used f or clipping . Phase allows you t o selec t the phase when one of the multiphase mo dels is selec ted in the Multiphase M odel Dialog Box (p.3248 ). Min, Max set the minimum and maximum v alues in the clipping r ange .There are two ways you c an set the Min and Max: •You c an set a v alue in teractively b y mo ving the indic ator in the dial ab ove the Min or Max field with the lef t mouse butt on.This will also cr eate a t emp orary sur face in the gr aphics windo w. Using the dial allows you t o pr eview the clipp ed sur faces b efore defining them. Note: Even though the clipp ed sur face is displa yed, it is only a t emp orary sur face.To clip the sur face, use the Clip butt on af ter deciding on the minimum and maximum v alues . 3841Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbon•You c an t ype in v alues in the Min and Max fields dir ectly. Clip S urface contains a list of sur faces fr om which y ou c an selec t the sur face to be clipp ed.You must selec t a sur face to mak e the Clip butt on a vailable . New S urface Name designa tes the name of the sur face to be created.The default is the c oncatenation of the sur face type and an in teger which is the new sur face ID . Clip creates the clipp ed sur face. (The or iginal sur face will r emain unchanged .) Comput e comput es the minimum and maximum v alues of the sc alar field acr oss the domain, and displa ys them in the Min and Max boxes. Manage ... opens the Surfaces D ialog Box (p.3933 ) in which y ou c an r ename and delet e sur faces and det ermine their sizes. 48.2.48. Iso-S urface Dialo g Box The Iso-S urface dialo g box allo ws you t o in teractively cr eate isosur faces.These sur faces c an b e iso valued sections of an e xisting sur face or of the en tire domain. For mor e eff ective use of the slider bar , press the Comput e butt on b efore using it. See Isosur faces (p.2748 ) for details ab out the it ems b elow. Controls Surface of C onstan t contains a list fr om which y ou c an selec t the sc alar field which will b e used f or isosur facing . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3842Ribbon R eference GuideMin displa ys the minimum field v alue , which is c omput ed when y ou click Comput e. Max displa ys the maximum field v alue , which is c omput ed when y ou click Comput e. Iso-V alues sets user-sp ecified iso values .There are two ways you c an set the Iso-V alues : •You c an set an iso value in teractively b y mo ving the slider with the lef t mouse butt on.This will also create a t emp orary isosur face in the gr aphics windo w. Using the slider allo ws you t o pr eview the isosur faces b efore defining them. Note: Even though the isosur face is displa yed, it is only a t emp orary surface.To create an isosur face, use the Create butt on af ter deciding on a par ticular iso value . •You c an t ype in iso values in the Iso-V alues field dir ectly, separ ating multiple v alues b y whit e spac e. Multiple iso values will b e contained in a single isosur face; tha t is, you c annot selec t subsur faces within the r esulting isosur face. From S urface contains a list of e xisting sur faces fr om which y ou c an selec t the sur face to be used f or isosur facing . If you do not selec t a sur face from the list , the isosur facing will b e performed on the en tire domain. From Z ones contains a list of c ell z ones fr om which y ou c an selec t the z one f or cr eating an isosur face. New S urface Name designa tes the name of the sur face to be created.The default is the c oncatenation of the sc alar field name and an in teger which is the new sur face ID . Create creates the sur face. Comput e comput es the minimum and maximum of the sc alar field acr oss the domain and displa ys them in the Min and Max boxes. Manage ... opens the Surfaces D ialog Box (p.3933 ) in which y ou c an r ename and delet e sur faces and det ermine their sizes. 48.2.49. Iso-V alue A daption D ialo g Box The Iso-V alue A daption dialo g box allo ws you t o mar k or r efine c ells inside or outside a sp ecified range of a selec ted sc alar func tion. This dialo g box is only a vailable if y ou ha ve used the f ollowing text command:mesh/adapt/revert-to-R19.2-user-interface ; not e tha t if y ou r evert the user in terface, you c annot undo it in the cur rent session, and some func tionalit y is no longer a vailable . Domain → Adapt → Mark/A dapt C ells → Iso-V alue ... 3843Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonControls Options contains r adio butt ons tha t control whether the c ells inside or outside the iso value r ange ar e mar ked f or refinemen t. Inside enables the mar king of c ells with v alues b etween Iso-M in and Iso-M ax. Outside enables the mar king of c ells with v alues less than Iso-M in or gr eater than Iso-M ax. Iso-V alues of contains a list fr om which y ou c an selec t the solution v ariable t o be used in the iso value adaption func tion. Min/M ax displa ys the minimum and maximum c ell v alues of the selec ted field v ariable .The r eal numb er field v alues are not editable; the y are pur ely inf ormational. Iso-M in defines the minimum iso value thr eshold . Iso-M ax defines the maximum iso value thr eshold . Manage ... opens the Manage A daption R egist ers D ialog Box (p.3848 ), which allo ws you t o displa y and manipula te adaption r egist ers tha t are gener ated using the Mark command . Controls... opens the Mesh A daption C ontrols D ialog Box (p.3851 ), which allo ws you t o control certain asp ects of the adaption pr ocess. Adapt adapts the mesh based on the iso values of the selec ted solution v ariable , the iso value r anges , and the Inside/Outside option. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3844Ribbon R eference GuideMark mar ks cells t o be refined based on the iso values of the selec ted quan tity, the iso value r anges , and the Inside/Outside option. This c ommand pr oduces an adaption r egist er. Comput e comput es the minimum and maximum c ell v alues of the selec ted solution v ariable and displa ys them in the Min and Max real numb er fields . 48.2.50. Lift Rep ort Definition D ialo g Box Solution → Rep orts → Definitions → New → Force Rep ort → Lift... 3845Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonControls Options Per Z one specifies whether or not the lif t for multiple w alls z ones should b e monit ored on each w all z one separ ately.When this option is tur ned off (the default), Fluen t comput es and monit ors the t otal lif t for all of the selec ted w alls z ones c ombined t ogether . Average O ver (Time-S teps), Average O ver (I terations) (optional) To ha ve Fluen t calcula te a r unning a verage f or the Lift Rep ort Definition you c an en ter a positiv e integer gr eater than 1 (the default) f or Average O ver. Specifying a numb er gr eater than 1 means that F luent will pr int, plot , and wr ite the r unning a verage value of the selec ted v ariable inst ead of the curr ent v alue of the same v ariable . The v alue r eported is a veraged o ver the last iterations/time st eps, wher e is y our sp ecified Av- erage O ver value .When the it eration/time st ep numb er is lo wer than , Fluent c alculat es the a v- erage of the a vailable v ariable v alues . Force Vector contains the c omp onen ts of the f orce vector. X,Y,Z are the c omp onen ts of the f orce vector along which the f orces will b e comput ed. Rep ort Files lists all of the r eport files wher e you c an wr ite the r eport definition da ta. Rep ort Plots lists all of the r eport plots wher e you c an plot the r eport definition da ta (assuming this r eport has the same units as the other r eport definitions included in the selec ted r eport plot). Create Rep ort File creates a new r eport file tha t includes this r eport definition. Rep ort Plot creates a new r eport plot tha t includes this r eport definition. Frequenc y specifies ho w fr equen tly the r eport definition is wr itten, plott ed, or pr inted t o the c onsole . Print to Console prints the v alue of the r eport definition t o the c onsole . Create Output P aramet er creates an output par amet er for this r eport definition with the name - op. Rep ort Output Type Lift Coefficien t specifies the r eport definition as a unitless quan tity. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3846Ribbon R eference GuideLift Force specifies tha t the r eport definition has units of f orce. Wall Z ones lists the z ones y ou c an selec t for lif t coefficien t or dr ag lif t computa tion. OK creates the r eport definition. Comput e comput es the v alue of the r eport definition a t the selec ted z one(s) and pr ints to the c onsole . 48.2.51. Line/R ake Surface Dialo g Box The Line/R ake Surface dialo g box allo ws you t o in teractively cr eate line and r ake sur faces. A rake is a linear , unif orm distr ibution of p oints b etween t wo endp oints. See Line and R ake Sur faces (p.2738 ) for details ab out the it ems b elow. Controls Options contains options r elated t o the line t ool. See Using the Line Tool (p.2740 ) for details ab out using this f eature. Line Tool enables the line t ool. Reset resets the line t ool to its default p osition. Type selec ts line or r ake as the sur face to be created. 3847Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonNumb er of P oints defines the numb er of p oints in the r ake sur face (inac tive for line sur faces). End P oints designa tes the c oordina tes of the first p oint (x0,y0,z0) and the last p oint (x1,y1,z1). Selec t Points with M ouse allows you t o selec t endp oints with the mouse .You c an selec t endp oints by click ing on lo cations in the active windo w with the mouse-pr obe butt on. (See Controlling the M ouse B utton F unctions (p.2833 ) for information ab out setting mouse butt on func tions .) New S urface Name designa tes the name of the new sur face.The default is the c oncatenation of the sur face type and an in teger which is the new sur face ID . Create creates the sur face. Manage ... opens the Surfaces D ialog Box (p.3933 ) in which y ou c an r ename and delet e sur faces and det ermine their sizes. 48.2.52. Manage A daption Regist ers D ialo g Box The Manage A daption Regist ers dialo g box pr ovides an in teractive mechanism f or cr eating , destr oying , and displa ying func tions f or mesh adaption. This dialo g box is only a vailable if y ou ha ve used the f ol- lowing t ext command:mesh/adapt/revert-to-R19.2-user-interface ; not e tha t if y ou r evert the user in terface, you c annot undo it in the cur rent session, and some func tionalit y is no longer available . Domain → Adapt → Manage Regist ers... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3848Ribbon R eference GuideControls Regist er A ctions contains op erations applied t o adaption or mask r egist ers. Change Type toggles the r egist er b etween adaption and mask t ypes. Adaption r egist ers ar e used t o initia te refining or coarsening of the mesh. Typic ally, mask r egist ers ar e combined with adaption r egist ers t o control the sc ope of the adaption pr ocess. Combine combines the selec ted adaption r egist ers t o create a h ybrid adaption func tion. In some instanc es, three new r egist ers ma y be created: a combina tion of the adaption r egist ers, a combina tion of the mask r egist ers, and then a c ombina tion of the t wo combined r egist ers. Delet e permanen tly disc ards the selec ted r egist ers. Mark Actions contains op erations applied t o the c ell mar kings defined in an adaption or mask r egist er. Exchange modifies the c ell mar kings in the f ollowing manner : all c ells or iginally mar ked f or refinemen t are mar ked f or coarsening , and all c ells or iginally mar ked f or coarsening ar e mar ked f or refinemen t. Invert modifies all the c ell mar kings in a mask r egist er in the f ollowing manner : all c ells tha t were or iginally mar ked as A CTIVE ar e mar ked INA CTIVE , and all c ells or iginally mar ked as INA CTIVE ar e mar ked A CTIVE . Note tha t this ac tion c an only b e applied t o mask r egist ers. 3849Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonLimit applies the adaption v olume limits t o the selec ted r egist ers. Fill mar ks for coarsening all c ells in the adaption r egist er tha t are not mar ked f or refinemen t. Regist ers contains a list fr om which y ou c an selec t the cur rent adaption and mask r egist ers.The a vailabilit y of man y of the ac tions in the dialo g box is based on the numb er and/or t ype of adaption r egist ers selec ted. Regist er Inf o provides the name , ID, numb er of c ells mar ked f or refinemen t and c oarsening , and the t ype of the most recently selec ted or deselec ted r egist er. Options ... opens the Adaption D ispla y Options D ialog Box (p.3778 ). Controls... opens the Mesh A daption C ontrols D ialog Box (p.3851 ), which allo ws you t o control certain asp ects of the adaption pr ocess. Adapt adapts the mesh based on the selec ted adaption r egist er.The Adapt butt on is not a vailable if mor e than one adaption r egist er is selec ted. Adaption func tions c omp osed of c ombina tions of adaption r egist ers can b e pr oduced using c ommands in the Regist er A ctions and Mark Actions boxes. Displa y displa ys the c ells mar ked f or adaption in the selec ted adaption r egist er in the ac tive gr aphics windo w. The Displa y butt on is not a vailable if mor e than one adaption r egist er is selec ted. Adaption func tions comp osed of c ombina tions of adaption r egist ers c an b e pr oduced using c ommands in the Regist er A ctions and Mark Actions boxes. 48.2.53. Merge Z ones D ialo g Box The Merge Z ones dialo g box allo ws you t o mer ge multiple z ones of the same t ype in to a single z one . See Merging Z ones (p.803) for details . Domain → Zones → Combine → Merge... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3850Ribbon R eference GuideControls Multiple Types contains a selec table list of the z one t ypes for which y ou c an mer ge multiple z ones .You selec t a t ype and the c orresponding z ones of tha t type will b e displa yed in the Zones of Type list. Zones of Type contains a list fr om which y ou c an selec t two or mor e zones t o be mer ged in to a single z one .The z ones are of the t ype selec ted in the Multiple Types list. Merge mer ges the selec ted z ones in to a single z one . If your c ase file has d ynamic z ones or mesh in terfaces, the Warning D ialog Box (p.3960 ) will op en and r equir e your input pr ior t o the mer ge. 48.2.54. Mesh A daption C ontrols D ialo g Box The Mesh A daption C ontrols dialo g box allo ws you t o set limits on the minimum c ell siz e, the min- imum and maximum numb er of c ells, and the c ell t ypes tha t can b e adapt ed. In addition, it allo ws you to vary the v olume w eigh ting of the gr adien t adaption func tion. This dialo g box is only a vailable if you ha ve used the f ollowing t ext command:mesh/adapt/revert-to-R19.2-user-interface ; note tha t if y ou r evert the user in terface, you c annot undo it in the cur rent session, and some func tion- ality is no longer a vailable . Domain → Adapt → More → Controls... Controls Options contains check butt ons tha t control the manner in which the mesh c an b e adapt ed. 3851Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonRefine toggles mesh adaption b y adding p oints. Coarsen toggles mesh adaption b y remo ving p oints. Zones contains a list of c ell z ones fr om which y ou c an selec t the z ones in which t o perform adaption (or mar king). By default , all c ell z ones ar e selec ted. Min C ell Volume restricts the siz e of the c ell tha t is c onsider ed f or refinemen t. Even if the c ell is mar ked f or refinemen t, it will not b e refined if its c ell v olume is less than this thr eshold v alue . Min # of C ells specifies the minimum numb er of c ells r equir ed in the mesh. Note When using the par allel solv er, the Min # of C ells value is not str ictly ob eyed, but provides an appr oxima te limit t o the minimum c ell c oun t tha t the adaption algor ithm will allo w. Max # of C ells limits the t otal numb er of c ells allo wed in the mesh. A value of z ero plac es no limits on the numb er of cells. Note When using the par allel solv er, the Max # of C ells value is not str ictly ob eyed, but provides an appr oxima te limit t o the maximum c ell c oun t tha t the adaption algor ithm will allo w. Max L evel of Refine specifies the maximum le vel of r efinemen t for the c ells. Volume Weigh t controls the v olume w eigh ting in the gr adien t adaption func tion. Valid v alues ar e between 0 and 1: 0 for no v olume w eigh ting and 1 f or full v olume w eigh ting . 48.2.55. Mesh In terfaces D ialo g Box The Mesh In terfaces dialo g box allo ws you t o aut oma tically or manually cr eate mesh in terfaces for use with sliding meshes (see Using S liding M eshes (p.1257 )) or multiple r eference frames (see Mesh Setup f or a M ultiple M oving R eference Frame (p.1240 )), or f or meshes with non-c onformal b oundar ies (see Non-C onformal M eshes (p.741)). For inf ormation ab out using this dialo g box, see Using a N on- Conformal M esh in ANSY S Fluen t (p.756). Domain → Interfaces → Mesh... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3852Ribbon R eference GuideControls Unassigned In terface Zones allows you t o create new mesh in terfaces using the aut oma tic or manual metho d. Note tha t the selec tion list a t the t op of the gr oup b ox (which lists in terface zones tha t ha ve not y et b een assigned t o an e xisting mesh in terface) is only used as par t of the aut oma tic metho d. Interface Name P refix specifies the pr efix used in the names of all the mesh in terfaces cr eated aut oma tically thr ough the Auto Create butt on. Options ... opens the Auto Create Options D ialog Box (p.3785 ), so y ou c an define settings tha t you w ant applied to the mesh in terfaces tha t are created aut oma tically thr ough the Auto Create butt on. Auto Create creates mesh in terfaces using the aut oma tic metho d, so tha t Fluen t is r esponsible f or det ermining which of the selec ted Unassigned In terface Zones can b e gr oup ed t ogether t o form the t wo sides of one or mor e mesh in terfaces. Note tha t mesh in terfaces tha t use the p eriodic or p eriodic r epeat option c annot b e created using this butt on, but must inst ead b e created thr ough the Manual C reate... butt on. Manual C reate... opens the Create/Edit M esh In terfaces D ialog Box (p.3794 ), so y ou c an cr eate mesh in terfaces using the manual metho d. Note tha t this metho d is only nec essar y for mesh in terfaces tha t use the p eriodic or p eriodic r epeat option. Mesh In terfaces allows you t o manage e xisting mesh in terfaces. Note tha t man y of the butt ons in this gr oup b ox are not accessible unless y ou mak e a selec tion fr om the list a t the t op. Edit... opens the Edit M esh In terfaces D ialog Box (p.3813 ), so y ou c an edit the name , the list of in terface zones assigned t o the in terface, and/or the in terface options . 3853Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonList prints inf ormation ab out the selec ted mesh in terface in the c onsole .When y ou click this butt on, ANSY S Fluen t will list the t wo interface boundar ies and (if y ou ha ve initializ ed the solution) all new z ones that were created (tha t is, wall and/or in terior z ones). Delet e delet es the selec ted mesh in terface. Note tha t this butt on c an only b e used on one mesh in terface at a time; if you w ould inst ead lik e to delet e multiple in terfaces in a single ac tion, you c an selec t them in the tr ee and use the r ight-click menu c ommand . Draw allows you t o displa y the selec ted mesh in terface (along with an y additional selec tions in the Unas- signed In terface Zones and/or Interface Zones lists) in the gr aphics windo w. Preview M esh M otion... opens the Mesh M otion D ialog Box (p.3599 ). Options ... opens the Interface Options D ialog Box (p.3838 ), wher e you c an up date which mesh in terfaces use the mapp ed option and set global par amet ers f or the mapp ed mesh in terfaces. Interface Zones highligh ts the in terface zones assigned t o the mesh in terface selec ted in the Mesh In terfaces group b ox, and allo ws you t o selec t specific in terface zones t o be displa yed in the gr aphics windo w using the Draw butt on. 48.2.56. Mesh M orpher/Optimiz er D ialo g Box The Mesh M orpher/Optimiz er dialo g box allo ws you t o use the mesh mor pher/optimiz er to def orm the mesh in or der t o solv e shap e optimiza tion pr oblems .You c an def orm the mesh manually , allo w a built-in optimiz er to define the def ormation in or der t o minimiz e an objec tive func tion, or use D esign Explor ation in ANSY S Workbench t o easily e xplor e a v ariety of def ormation sc enar ios. See Using the Mesh M orpher/Optimiz er (p.3181 ) for fur ther details . Design → Paramet er-B ased → Optimiz er... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3854Ribbon R eference GuideControls Regions tab allo ws you t o define the r egions of the domain wher e the mesh will b e def ormed in or der t o optimiz e the shap e. Control P oint Distribution allows you t o selec t the w ay in which y ou will define the lo cations of the c ontrol p oints, as w ell as the k inds of motions y ou c an apply . Regular specifies tha t the c ontrol p oints will b e spr ead in a r egular distr ibution thr oughout the en tire deformation r egion. The numb er of c ontrol p oints along each of the defining dir ection v ectors will b e sp ecified in the Control P oints group b ox.The motion of the c ontrol p oints will b e limit ed to transla tions , as the abilit y to define r otational or r adial motions will not b e available . 3855Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonUnstr uctured specifies tha t control p oint locations will b e sp ecified b y right-click ing with the mouse on boundar y zones , distr ibuting an appr oxima te numb er thr oughout a z one , or b y en tering coordina tes, using the Define C ontrol P oints D ialog Box (p.3800 ).The motion of the c ontrol points will b e able t o be defined as tr ansla tions , as r otations ab out a p oint / axis , or r adially about a p oint / axis . Name provides c ontrols f or the def ormation r egions y ou ar e defining .The upp er text-en try box defines the name of the r egion tha t is cr eated when y ou click the Create butt on.The lo wer selec tion list allo ws you t o selec t a r egion tha t has alr eady been cr eated, in or der t o displa y it in the gr aphics windo w, modify the settings via the Modify butt on, or delet e the r egion via the Delet e butt on. Update from Z ones allows you t o create a b ounding b ox tha t defines the def ormation r egion. Boundar y Zones specifies the b oundar y zones tha t will b e used t o gener ate a b ounding b ox for the def ormation region when y ou click the Define butt on. Define updates the v alues in the Origin ,Direction-1 Vector,Direction-2 Vector, and Size of Region group b oxes based on a b ounding b ox tha t enc ompasses the selec tions in the Boundar y Zones list, and pr eview s the b ounding b ox in gr een in the gr aphics windo w. Enlar ge increases the siz e of the b ounding b ox created b y the Define butt on, and pr eview s the r evised bounding b ox in gr een in the gr aphics windo w. Reduc e decr eases the siz e of the b ounding b ox created b y the Define butt on, and pr eview s the r evised bounding b ox in gr een in the gr aphics windo w. Update from P lane Tool updates the v alues in the Direction-1 Vector and Direction-2 Vector group b oxes based on the settings in the plane t ool. See Using the P lane Tool (p.2744 ) for inf ormation ab out the plane t ool.This butt on is only a vailable f or 3D c ases . Update from Line Tool updates the v alues in the Direction-1 Vector and Direction-2 Vector group b oxes based on the settings in the line t ool. See Using the Line Tool (p.2740 ) for inf ormation ab out the line t ool.This butt on is only a vailable f or 2D c ases . Origin allows you t o define the C artesian c oordina tes of the or igin of the def ormation r egion. X defines the x coordina te of the or igin of the def ormation r egion. Y defines the y coordina te of the or igin of the def ormation r egion. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3856Ribbon R eference GuideZ defines the z coordina te of the or igin of the def ormation r egion. This numb er-en try box is only available f or 3D c ases . Direction-1 Vector allows you t o define a v ector tha t acts as the first dir ection of the def ormation r egion r elative to the Origin . X defines the x comp onen t of the first dir ection v ector of the def ormation r egion. Y defines the y comp onen t of the first dir ection v ector of the def ormation r egion. Z defines the z comp onen t of the first dir ection v ector of the def ormation r egion. This numb er- entry box is only a vailable f or 3D c ases . Direction-2 Vector defines a v ector tha t is used t o calcula te the sec ond dir ection of the def ormation r egion r elative to the Origin . For 2D c ases , the v alues in the Direction-2 Vector group b ox are aut oma tically defined by ANSY S Fluen t to be perpendicular t o the Direction-1 Vector. For 3D c ases , the v ector defined b y the Direction-2 Vector group b ox is pr ojec ted on to a plane tha t intersec ts the Origin and is p erpen- dicular t o the v ector defined in the Direction-1 Vector group b ox, in or der t o calcula te the sec ond direction. X defines the x comp onen t of the v ector used t o calcula te the sec ond dir ection of the def ormation region. This numb er-en try box is only editable f or 3D c ases . Y defines the y comp onen t of the v ector used t o calcula te the sec ond dir ection of the def ormation region. This numb er-en try box is only editable f or 3D c ases . Z defines the z comp onen t of the v ector used t o calcula te the sec ond dir ection of the def ormation region. This numb er-en try box is only a vailable f or 3D c ases . Size of Region allows you t o define the o verall dimensions of the def ormation r egion. Direction-1 defines the length of the def ormation r egion along the dir ection sp ecified b y the Direction-1 Vector group b ox. Direction-2 defines the length of the def ormation r egion along the dir ection sp ecified b y the Direction-2 Vector group b ox. Direction-3 defines the length of the def ormation r egion along the thir d axis (tha t is, the cr oss pr oduc t of the vectors defined b y the Direction-1 Vector and Direction-2 Vector group b oxes).This numb er- entry box is only a vailable f or 3D c ases . 3857Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonBoundar y Continuit y allows you t o sp ecify whether the mesh tr ansitions ar e smo oth or abr upt wher ever the mesh in tersec ts with the limits of the def ormation r egion. This gr oup b ox is only a vailable when Unstr uctured is se- lected fr om the Control P oint Distribution list. Smooth Transitions enables smo oth mesh tr ansitions wher ever the mesh in tersec ts with the limits of the def ormation region, based on the cr eation of sta tionar y control p oints at those in tersec tions . Displa y Control P oints displa ys the sta tionar y control p oints cr eated when the Smooth Transitions option is enabled . Control P oints allows you t o define the c ontrol p oints for the def ormation r egions . Direction-1 defines the numb er of c ontrol p oints for the def ormation r egion selec ted in the Name group b ox along the dir ection sp ecified b y the Direction-1 Vector group b ox.This numb er-en try box is only available when Regular is selec ted fr om the Control P oint Distribution list. Direction-2 defines the numb er of c ontrol p oints for the def ormation r egion selec ted in the Name group b ox along the dir ection sp ecified b y the Direction-2 Vector group b ox.This numb er-en try box is only available when Regular is selec ted fr om the Control P oint Distribution list. Direction-3 defines the numb er of c ontrol p oints for the def ormation r egion selec ted in the Name group b ox along the thir d axis (tha t is, the cr oss pr oduc t of the v ectors defined b y the Direction-1 Vector and Direction-2 Vector group b oxes).This numb er-en try box is only a vailable f or 3D c ases when Regular is selec ted fr om the Control P oint Distribution list. Define ... opens the Define C ontrol Points D ialog Box (p.3800 ), which y ou c an use t o define the c ontrol p oints. This butt on is only a vailable when Unstr uctured is selec ted fr om the Control P oint Distribution list. Preview displa ys (in gr een) the b ounding b ox tha t results fr om the cur rent settings in the Origin ,Direction- 1 Vector,Direction-2 Vector, and Size of Region group b oxes. Create creates a new def ormation r egion with the name sp ecified in the upp er text-en try box of the Name group b ox and with the settings defined using the Origin ,Direction-1 Vector,Direction-2 Vector, Size of Region , and (f or regular c ontrol p oint distr ibutions) Control P oints group b oxes.The newly created def ormation r egion will b e added t o and selec ted in the lo wer Name selec tion list , and will be displa yed (in blue) in the gr aphics windo w. Modify modifies the sa ved settings f or the def ormation r egion selec ted in the lo wer Name selec tion list and displa ys the mo dified r egion in the gr aphics windo w. Delet e delet es the def ormation r egion selec ted in the lo wer Name selec tion list. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3858Ribbon R eference GuideConstr aints tab allo ws you t o define the c onstr aints on the b oundar y zones , in or der t o limit the fr eedom of par ticular zones tha t fall within the def ormation r egion(s) dur ing the mor phing of the mesh. Zones allows you t o selec t the b oundar y zones f or which y ou ar e defining a c onstr aint. Option specifies the c onstr aint on the b oundar y zones selec ted fr om the Zones list. Unconstr ained specifies tha t the b oundar y zones ar e complet ely fr ee to be def ormed acc ording t o the assigned paramet ers. Passiv e specifies tha t the no des of the b oundar y zones ar e par tially c onstr ained t o varying degr ees, based on their pr oximit y to adjac ent boundar y zones tha t are fix ed.The no des in a passiv e boundar y zone b ehave in a similar manner t o the in terior mesh no des, in or der t o ensur e tha t ther e is a smo oth tr ansition b etween fix ed and unc onstr ained b oundar y zones . Fixed specifies tha t the b oundar y zones ar e fix ed and will not b e def ormed . Displa y displa ys the selec ted Zones in the gr aphics windo w. Summar y prints a list in the c onsole tha t summar izes the c onstr aint definitions f or all of the b oundar y zones . Deformation tab allo ws you t o define the def ormation. Numb er of P aramet ers defines the numb er of par amet ers a vailable t o define the motion of the c ontrol p oints. Paramet er Values allows you t o define either the magnitude of def ormation asso ciated with each par amet er (when y ou are manually sp ecifying the def ormation or using D esign Explor ation in ANSY S Workbench t o explor e multiple def ormation sc enar ios) or the b ounds f or each par amet er (when y ou ar e using a built-in optimiz er). par1 ,par2 ... specify the magnitude of def ormation asso ciated with each par amet er.You c an en ter a numer ic value in the field or use the icon t o create or assign an input par amet er (see Selec t Input P ara- met er D ialog Box (p.3472 ) for details). These fields and ic ons ar e only a vailable when none or workbench is selec ted fr om the Optimiz er drop-do wn list in the Optimiz er tab . Note tha t the value en tered her e will sp ecify a length in met ers f or tr ansla tions and r adial motions , and will specify an angle in degr ees f or rotations; these units will b e used r egar dless of wha t units y ou ar e using in the c ase. Apply saves definitions f or the par amet er fields in the Paramet er Values group b ox.This butt on is only available when none or workbench is selec ted fr om the Optimiz er drop-do wn list in the Optim- izer tab . 3859Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonSet B ounds ... opens the Paramet er B ounds D ialog Box (p.3880 ), wher e you c an define str ict minimum and max- imum v alues f or the par amet ers. Note tha t this butt on is not a vailable when workbench is selec ted from the Optimiz er drop-do wn list in the Optimiz er tab . Motion S ettings ... opens the Motion S ettings D ialog Box (p.3867 ), wher e you c an define the motion of the c ontrol p oints. Deform applies the cur rent settings in the Paramet er Values group b ox, mo difies the mesh, and up dates the mesh displa y in the gr aphics windo w.This butt on is only a vailable when none is selec ted fr om the Optimiz er drop-do wn list in the Optimiz er tab . Check displa ys a mesh check r eport in the c onsole f or the mesh displa yed in the gr aphics windo w.This butt on is only a vailable when none is selec ted fr om the Optimiz er drop-do wn list in the Optimiz er tab.The mesh check r eport provides v olume sta tistics , mesh t opology and p eriodic b oundar y inf orm- ation, verification of simple x coun ters, and v erification of no de p osition with r eference to the axis for axisymmetr ic cases , in the same manner as the Check butt on in the Gener al task page (see Check ing the M esh (p.788) for details). Reset undo es an y mo dific ations made t o the mesh as a r esult of the Deform butt on and up dates the mesh displa y in the gr aphics windo w. Optimiz er tab allo ws you t o define the settings f or the optimiz er. Optimiz er specifies which optimiz er is used .The choic es include none (for manual def ormation); compass , newuoa ,powell,rosenbr ock,simple x, and torczon (for optimiza tion in ANSY S Fluen t); and work- bench (for optimizing using D esign Explor ation in ANSY S Workbench). Note tha t workbench is only available if y ou ha ve launched y our ANSY S Fluen t session fr om ANSY S Workbench. For inf ormation about ho w the built-in optimiz ers func tion or ho w to use D esign Explor ation, see Design A naly sis and Optimiza tion (p.3105 ) in the U ser's G uide or Working With Input and Output P aramet ers in Work- bench in the ANSY S Fluen t in Workbench U ser's G uide , respectively. Objec tive Func tion D efinition... opens the Objec tive Function D efinition D ialog Box (p.3876 ), wher e you c an sp ecify the f ormat of the objec tive func tion tha t will b e minimiz ed dur ing the optimiza tion pr ocess.This butt on is not a vailable if none or workbench is selec ted fr om the Optimiz er drop-do wn list. Optimiz er S ettings allows you t o sp ecify the optimiz er settings .This gr oup b ox is not a vailable if none or workbench is selec ted fr om the Optimiz er drop-do wn list. Maximum N umb er of D esigns defines the maximum numb er of design stages the optimiz er will under go t o reach the sp ecified objec tive func tion. Maximum I terations p er D esign defines the maximum numb er of it erations ANSY S Fluen t will p erform for each design change . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3860Ribbon R eference GuideOptimiz er C onvergenc e Criteria defines the c onvergenc e criteria for the optimiz er. Initial P aramet er Variation defines ho w much the par amet ers will b e allo wed t o vary dur ing the initial c alcula tions when newuoa is selec ted fr om the Optimiz er drop-do wn list. Mesh Q ualit y allows you t o enable and define a mesh qualit y check: if the or thogonal qualit y (as defined in Mesh Qualit y (p.719)) for an y cell of a mesh is less than a sp ecified v alue , no solution is c alcula ted f or the mesh and F luen t proceeds t o the ne xt design stage .This gr oup b ox is not a vailable if none is selec ted from the Optimiz er drop-do wn list. Rejec t Poor Q ualit y M eshes enables the c onsider ation of or thogonal qualit y when det ermining whether a solution should b e calcula ted f or a mesh. Minimum Or tho gonal Q ualit y defines the minimum or thogonal qualit y value e very cell must ha ve in or der f or a solution t o be calcula ted f or a mesh. Values ma y range fr om 0–1 (wher e 0 represen ts the w orst qualit y). Case and D ata F ile S ets allows you t o enable the aut oma tic sa ving of in termedia te case and da ta files a t specified in tervals during the optimiza tion r un, so tha t you c an r estar t an in terrupted solution in the same or a diff erent Fluen t session without incr easing the o verall numb er of design it erations needed t o reach c onvergenc e. This gr oup b ox is not a vailable if none or workbench is selec ted fr om the Optimiz er drop-do wn list. Save Every specifies the fr equenc y (in numb er of design it erations) tha t you w ant intermedia te case and da ta file sets sa ved. Note tha t the default v alue is 0, which sp ecifies tha t no in termedia te files will b e saved. Maximum N umb er Retained specifies the maximum numb er of in termedia te case and da ta files sets y ou w ant to retain. After the maximum limit of file sets has b een sa ved, ANSY S Fluen t begins o verwriting the ear liest e xisting intermedia te file set. File N ame specifies a r oot name f or the in termedia te case and da ta file sets , which will b e app ended with a numb er tha t represen ts the design it eration dur ing which it w as sa ved. Note tha t you c an include a folder pa th in the file name if y ou w ant the files sa ved outside of the w orking f older . Initializa tion provides settings tha t det ermine ho w the solution v ariables ar e treated af ter the mesh is def ormed during the optimiza tion pr ocess.This gr oup b ox is not a vailable if none or workbench is selec ted from the Optimiz er drop-do wn list. Metho d allows you t o selec t one of the f ollowing: Initializ e Data A fter M orphing specifies tha t the solution v ariables should b e initializ ed t o the v alues defined in the Solution Initializa tion task page af ter def ormation. 3861Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonContinue with C urrent Data specifies tha t the solution v ariables should r emain the v alues obtained in the pr evious design iteration. Read D ata F ile A fter M orphing specifies tha t the solution v ariables ar e set t o the v alues obtained fr om the da ta file sp ecified in the Data F ile N ame text-en try box after def ormation. This selec tion is not a vailable when newuoa is selec ted fr om the Optimiz er drop-do wn list. Data F ile N ame specifies the da ta file fr om which the solution v ariables ar e obtained when Read D ata F ile A fter Morphing is selec ted. Execut e Commands allows you t o sp ecify c ommands (t ext commands or c ommand macr os) tha t will b e run dur ing the optimiza tion r uns of the mesh mor pher/optimiz er.This gr oup b ox is not a vailable if none ,newuoa , or workbench is selec ted fr om the Optimiz er drop-do wn list. Initial C ommands specifies the c ommands tha t will b e run af ter the design has b een mo dified , but b efore ANSY S Fluen t has star ted t o run the c alcula tion f or tha t design stage . End C ommands specifies the c ommands tha t will b e run af ter the solution has r un and c onverged f or a design stage . Monit or... opens the Optimiza tion Hist ory Monit or D ialog Box (p.3878 ), which allo ws you t o plot and/or r ecord how the v alue of the objec tive func tion v aries with each design stage .This butt on is not a vailable if none ,newuoa , or workbench is selec ted fr om the Optimiz er drop-do wn list. Apply saves the settings in the Optimiz er tab . Summar y displa ys a summar y of the mesh mor pher/optimiz er settings in the c onsole . Optimiz e initia tes the optimiza tion pr ocess using the settings sa ved in all of the tabs of the Mesh M orpher/Op- timiz er dialo g box.This butt on is not a vailable if none or workbench is selec ted fr om the Optimiz er drop-do wn list. 48.2.57. Mixing P lanes D ialo g Box The Mixing P lanes dialo g box allo ws you t o define the mixing planes f or a mixing plane mo del. See Setting U p the M ixing P lane M odel (p.1243 ) for details ab out using the it ems b elow. Domain → Mesh M odels → Mixing P lanes ... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3862Ribbon R eference GuideControls Mixing P lane contains a list fr om which y ou c an selec t an e xisting mixing plane , and an inf ormational field in which ANSY S Fluen t displa ys the name of the cur rently selec ted (or most r ecently cr eated) mixing plane . Upstr eam Z one , Downstr eam Z one contain lists fr om which y ou c an selec t the b oundar ies on the upstr eam and do wnstr eam sides of the mixing plane , and inf ormational fields tha t sho w the names of the z one y ou selec ted in each list. (You cannot edit these fields; the name in each field will b e the name of the z one y ou selec ted in the list b elow it.) Interpolation P oints specifies the numb er of r adial or axial lo cations used in c onstr ucting the b oundar y pr ofiles f or cir cumf er- ential a veraging .This it em app ears only in 3D . Mixing P lane G eometr y defines the geometr y of the mixing plane in terface.This it em app ears only in 3D . Radial specifies tha t inf ormation a t the mixing plane in terface is t o be cir cumf erentially a veraged in to pr ofiles that vary in the r adial dir ection, for e xample , , . Axial specifies tha t cir cumf erentially a veraged pr ofiles ar e to be constr ucted tha t vary in the axial dir ection, for e xample , , . 3863Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonGlobal P aramet ers contains par amet ers r elated t o the mixing plane c alcula tion. Averaging M etho d consists of thr ee pr ofile a veraging metho ds. Area is the default metho d and is e xpressed using Equa tion 2.17 in the Theor y Guide . Mass provides b etter represen tation of the t otal quan tities than the ar ea a veraging metho d. It is defined by Equa tion 2.18 of the Theor y Guide . Mixed-Out is most r epresen tative of non-unif orm flo w pr ofiles and is e xpressed using Equa tion 2.20 in the Theor y Guide . Under-Relaxa tion specifies the under-r elaxa tion fac tor for up dating the b oundar y values a t mixing planes . Apply sets the sp ecified Under-Relaxa tion . Default sets the Under-Relaxa tion to its default v alue , as assigned b y ANSY S Fluen t. After execution, the Default butt on b ecomes the Reset butt on. Reset resets the Under-Relaxa tion to its most r ecently sa ved v alue (tha t is, the v alue b efore Default was selec ted). After execution, the Reset butt on b ecomes the Default butt on. Create creates the sp ecified mixing plane (and assigns it a name in the Mixing P lane field). Delet e delet es the mixing plane selec ted under Mixing P lane . 48.2.58. Momen t Rep ort Definition D ialo g Box Solution → Rep orts → Definitions → New → Force Rep ort → Momen t... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3864Ribbon R eference GuideControls Options Per Z one specifies whether or not momen ts for multiple w alls should b e monit ored on each w all separ ately.When this option is tur ned off (the default), Fluen t comput es and monit ors the t otal f orce for all of the se- lected w alls c ombined t ogether . 3865Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonAverage O ver (Time-S teps), Average O ver (I terations) (optional) To ha ve Fluen t calcula te a r unning a verage f or the Momen t Rep ort Definition you c an enter a p ositiv e integer gr eater than 1 (the default) f or Average O ver. Specifying a numb er gr eater than 1 means that F luent will pr int, plot , and wr ite the r unning a verage value of the selec ted v ariable inst ead of the curr ent v alue of the same v ariable . The v alue r eported is a veraged o ver the last iterations/time st eps, wher e is y our sp ecified Av- erage O ver value .When the it eration/time st ep numb er is lo wer than , Fluent c alculat es the a v- erage of the a vailable v ariable v alues . Momen t Center contains the C artesian c oordina tes of the momen t center. Momen t Axis contains the C artesian c oordina tes of the momen t vector to be monit ored. Rep ort Files lists all of the r eport files wher e you c an wr ite the r eport definition da ta. Rep ort Plots lists all of the r eport plots wher e you c an plot the r eport definition da ta (assuming this r eport has the same units as the other r eport definitions included in the selec ted r eport plot). Create Rep ort File creates a new r eport file tha t includes this r eport definition. Rep ort Plot creates a new r eport plot tha t includes this r eport definition. Frequenc y specifies ho w fr equen tly the r eport definition is wr itten, plott ed, or pr inted t o the c onsole . Print to Console prints the v alue of the r eport definition t o the c onsole . Create Output P aramet er creates an output par amet er for this r eport definition with the name - op. Rep ort Output Type Momen t Coefficien t specifies the r eport definition as a unitless quan tity. Momen t specifies tha t the r eport definition has units of f orce. Wall Z ones lists the z ones y ou c an selec t for momen t computa tion. Highligh t Zones when enabled , highligh ts the selec ted Wall Z ones in the gr aphics windo w. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3866Ribbon R eference GuideOK creates the r eport definition. Comput e comput es the v alue of the r eport definition a t the selec ted z one(s) and pr ints to the c onsole . 48.2.59. Motion S ettings D ialo g Box The Motion S ettings dialo g box allo ws you t o define the motion of the c ontrol p oints, as par t of the definition of the def ormation pr oduced b y the mesh mor pher/optimiz er. Note tha t the c ontrols and workflow of this dialo g box are very much dep enden t on the selec tion in the Control P oint Distribution list in the Regions tab of the Mesh M orpher/Optimiz er dialo g box. See Using the M esh M orpher/Op- timiz er (p.3181 ) for details ab out using this dialo g box. The Motion S ettings dialo g box is op ened fr om the Mesh M orpher/Optimiz er D ialog Box (p.3854 ). Controls (when Regular is selec ted fr om the Control P oint Distribution list in the Regions tab of the Mesh M orpher/Optimiz er dialo g box) 3867Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonRegion selec ts the def ormation r egion f or which y ou ar e assigning par amet ers and tr ansla tion dir ections t o control p oints. Control P oints defines the c ontrol p oints to which y ou ar e assigning par amet ers and tr ansla tion dir ections . Selec tion Tools provides t ools f or selec ting the c ontrol p oints to which y ou ar e assigning par amet ers and tr ansla tion directions . Mouse-P robe allows you t o sp ecify the Control P oints by click ing in the gr aphics windo w with the mouse-pr obe butt on (which is the r ight mouse butt on, by default). Inde xed G rouping allows you t o selec t the c ontrol p oints based on their assigned indic es. i allows you t o selec t from a list of c ontrol p oint inde x numb ers, which iden tify the lo cation in a sequenc e (star ting a t the or igin of the r egion) of c ontrol p oints along the dir ection-1 v ector (as defined in the Regions tab of the Mesh M orpher/Optimiz er dialo g box). j allows you t o selec t from a list of c ontrol p oint inde x numb ers, which iden tify the lo cation in a sequenc e (star ting a t the or igin of the r egion) of c ontrol p oints along the dir ection-2 v ector (as defined in the Regions tab of the Mesh M orpher/Optimiz er dialo g box). k allows you t o selec t from a list of c ontrol p oint inde x numb ers, which iden tify the lo cation in a sequenc e (star ting a t the or igin of the r egion) of c ontrol p oints along the dir ection-3 v ector (as defined—though not displa yed—in the Regions tab of the Mesh M orpher/Optimiz er dialo g box). Selec t adds the c ontrol p oints tha t satisfy the selec ted inde x criteria (tha t is, the selec tions fr om the i,j, and k drop-do wn lists) t o the list of selec ted Control P oints. Deselec t remo ves the c ontrol p oints tha t satisfy the selec ted inde x criteria (tha t is, the selec tions fr om the i,j, and k drop-do wn lists) fr om the list of selec ted Control P oints. Paramet ers specifies the names of the par amet ers (whose v alues ar e displa yed in the Paramet er Values group b ox in the Deformation tab of the Mesh M orpher/Optimiz er dialo g box) tha t you ar e assigning t o the Control P oints.The pr oduc ts of the v alues asso ciated with these par amet ers and the settings sp ecified in the Transla tion D irection group b ox define the displac emen t of the c ontrol p oints dur ing manual deformation. Transla tion D irection allows you t o define c oefficien ts in the x,y, and (f or 3D c ases) z directions t o sc ale the magnitude of de- formation f or the selec ted par amet ers. If you use a built-in optimiz er, these c oefficien ts pr ovide the dir- ection of the displac emen t of the c ontrol p oints and the optimiz er det ermines the o verall magnitude of displac emen t. Alternatively, if you manually sp ecify the def ormation or use D esign Explor ation in ANSY S Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3868Ribbon R eference GuideWorkbench t o explor e multiple def ormation sc enar ios, the v alues y ou en ter in the Transla tion D irection group b ox are multiplied with the v alues of the Paramet ers (as displa yed in the Paramet er Values group box in the Deformation tab of the Mesh M orpher/Optimiz er dialo g box) to define the displac emen t of the c ontrol p oints. X defines the sc aling c oefficien t applied t o the def ormation par amet er in the x direction. Y defines the sc aling c oefficien t applied t o the def ormation par amet er in the y direction. Z defines the sc aling c oefficien t applied t o the def ormation par amet er in the z direction. This numb er- entry box is only a vailable f or 3D c ases . Apply saves the selec tions made in the Paramet ers selec tion list and the v alues en tered in the Transla tion Direction group b ox, and assigns these par amet er settings t o the c ontrol p oints selec ted in the Control Points selec tion list. Read ... allows you t o define y our motion settings b y reading an ASCII t ext file . See Mesh M orpher/Optimiz er File Formats (p.3986 ) for fur ther details ab out the t ext file f ormat. Summar y displa ys a summar y of the sa ved motion settings in the c onsole . Write... allows you t o wr ite your sa ved motion settings t o an ASCII t ext file . See Mesh M orpher/Optimiz er File Formats (p.3986 ) for fur ther details ab out the t ext file f ormat. 3869Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonControls (when Unstr uctured is selec ted fr om the Control P oint Distribution list in the Regions tab of the Mesh M orpher/Optimiz er dialo g box) Name provides c ontrols f or the motions y ou ar e defining .The upp er text-en try box defines the name of the motion tha t is cr eated when y ou click the Create butt on (which b y default is based on the t ype of motion and the r elated par amet er).The lo wer selec tion list allo ws you t o selec t a motion tha t has alr eady been created, in or der t o displa y the selec tions asso ciated with it , or t o mo dify or delet e the motion using the Modify or Delet e butt ons, respectively. Paramet er allows you t o selec t the par amet er (whose v alue is displa yed in the Paramet er Values group b ox in the Deformation tab of the Mesh M orpher/Optimiz er dialo g box) for the motion. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3870Ribbon R eference GuideType allows you t o sp ecify the t ype of motion y ou w ant to define . Transla tion specifies tha t the motion is a tr ansla tion, based on the settings in the Direction group b ox. Rota tion specifies tha t the motion is a r otation ab out a p oint (for 2D) or an axis (f or 3D), based on the settings in the Axis Or igin group b ox and (f or 3D c ases) Axis D irection group b ox. Radial specifies tha t the motion is defined r adially ab out a p oint (for 2D) or an axis (f or 3D), based on the settings in the Axis Or igin group b ox and (f or 3D c ases) Axis D irection group b ox. Direction allows you t o define c oefficien ts in the X,Y, and (f or 3D c ases) Z directions t o sc ale the magnitude of deformation f or the selec ted par amet er. If you use a built-in optimiz er, these c oefficien ts pr ovide the direction of the displac emen t of the c ontrol p oints and the optimiz er det ermines the o verall magnitude of displac emen t. Alternatively, if you manually sp ecify the def ormation or use D esign Explor ation in ANSY S Workbench t o explor e multiple def ormation sc enar ios, the v alues y ou en ter in the Direction group b ox are multiplied with the v alues of the Paramet er (as displa yed in the Paramet er Values group b ox in the Deformation tab of the Mesh M orpher/Optimiz er dialo g box) to define the displac emen t of the c ontrol points. This gr oup b ox is only a vailable when Transla tion is selec ted fr om the Type list. Axis D irection allows you t o define the X,Y, and Z comp onen ts of the v ector ab out which the c ontrol p oints will r otate or mo ve radially , when the selec tion in the Type list is Rota tion or Radial , respectively.This gr oup b ox is only a vailable f or 3D c ases . Axis Or igin allows you t o define the X,Y, and (f or 3D c ases) Z coordina tes of the or igin ab out which the c ontrol p oints will r otate or mo ve radially , when the selec tion in the Type list is Rota tion or Radial , respectively. Control P oints allows you t o selec t the c ontrol p oints tha t will under go the motion. Selec tion Tools provides t ools f or selec ting the c ontrol p oints tha t will under go the motion. Mouse-P robe allows you t o sp ecify the Control P oints by click ing in the gr aphics windo w with the mouse-pr obe butt on (which is the r ight mouse butt on, by default). Create creates a new motion based on the cur rently displa yed settings . Modify modifies the sa ved settings f or the motion selec ted in the lo wer Name selec tion list. Delet e delet es the motion selec ted in the lo wer Name selec tion list. 3871Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonRead ... allows you t o define y our motion definitions b y reading an ASCII t ext file . See Mesh M orpher/Optimiz er File F ormats (p.3986 ) for fur ther details ab out the t ext file f ormat. Summar y displa ys a summar y of the sa ved motion definitions in the c onsole . Write... allows you t o wr ite your sa ved motion definitions t o an ASCII t ext file . See Mesh M orpher/Optimiz er File Formats (p.3986 ) for fur ther details ab out the t ext file f ormat. 48.2.60. Multi E dit D ialo g Box Setup → Boundar y Conditions → Multi-E dit... Controls Master Z one N ame non-editable field displa ying the name of the "mast er" b oundar y, which c annot b e deselec ted in the Zone List .When the dialo g box is first op ened , the v alues of the "mast er z one" ar e sho wn in all fields . Zone List lists all of the z ones tha t are compa tible f or multi-editing with the "mast er" z one .The selec ted z ones ar e the ones tha t will b e mo dified on Apply . indic ates tha t the v alue of this setting v aries b etween the selec ted b oundar ies in the Zone List . indic ates tha t the displa yed v alue will b e applied t o the selec ted b oundar ies in the Zone List when y ou click Apply . Apply applies the settings mar ked with the icon t o the selec ted b oundar ies in the Zone List . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3872Ribbon R eference GuideRefer to Editing M ultiple B oundar y Conditions a t Onc e (p.1018 ) for additional inf ormation ab out this func tionalit y. Note tha t while this image sho ws the Multi E dit Velocity Inlet S ettings dialo g box, the func tionalit y tha t is sp ecific t o multi-editing is c onsist ent acr oss the diff erent multi-edit dialo g boxes. For inf ormation on sp ecific settings of b oundar y conditions , refer to Boundar y Conditions Task Page (p.3479 ) (which c ontains descr iptions of each b oundar y's dialo g box), and Boundar y Condi- tions (p.912). 48.2.61. New Rep ort File D ialo g Box Solution → Rep orts → File... Click New... in the Rep ort File D efinitions dialo g box to op en the New Rep ort File dialo g box. Controls Name editable field displa ying the name of the r eport file . Active check b ox (enabled b y default) tha t det ermines if the file is wr itten dur ing the solution c alcula tion. Available Rep ort Definitions lists all of the e xisting r eport definitions not cur rently par t of this r eport file . Add>> moves the selec ted r eport definition(s) t o the Selec ted Rep ort Definitions list. 3873Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbon<> moves the selec ted r eport definition(s) t o the Selec ted Rep ort Definitions list. <> adds the selec ted v ariables and z ones t o the R OM. Selec ted f or R OM lists all of the selec ted v ariables and their asso ciated lo cations f or the R OM. Delet e remo ves the selec ted v ariables and z ones fr om the Selec ted f or R OM list. Evalua te tab Paramet ers used f or R OM cr eation: lists all of the v ariables tha t were used in cr eation of the r educ ed or der mo del (R OM). The Min-M ax R ange on the r ight of the fields lists the acc epted input r anges f or the numb er en try fields . Evalua te evalua tes the c ase using the v alues y ou sp ecify f or the list ed par amet ers. 3901Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbon48.2.75. Ref erenc e Frame D ialo g Box The Referenc e Frame dialo g box allo ws you t o cr eate lo cal reference frames either with the c oordina tes and or ientation tha t you sp ecify or b y tracking a c ell z one . Refer to Reference Frames (p.738) additional information. Controls Definition M etho d specifies ho w you w ant to define the r eference frame . Parent (U ser D efined only) specifies the par ent reference frame . Zone ( Track b y Zone only) specifies which c ell z one this r eference frame will tr ack. Motion (U ser D efined Only) allows you t o sp ecify a motion f or this r eference frame (acc omplished in the Motion tab . Linear Velocity (M otion tab) is the linear v elocity with r espect to the par ent reference frame or ientation. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3902Ribbon R eference GuideRota tional Velocity (M otion tab) is the r otational v elocity with r espect to the par ent reference frame or ientation. Rota tion A xis is the axis ab out which the r otational v elocity will b e applied . Origin specifies the or igin of the r eference frame . Axis-1 Or ientation specifies the or ientation of the selec ted axis . Axis-2 Or ientation specifies the or ientation of the sec ond axis . By default F luen t do es this aut oma tically, however you c an disable Automa tic and sp ecify the or ientation manually . Current State (tab) shows you the cur rent origin and ax es dir ections of the r eference frame with r espect to the global r eference frame . 48.2.76. Region A daption D ialo g Box The Region A daption dialo g box allo ws you t o mar k or r efine c ells inside or outside a sp ecified r egion defined b y text or mouse input. This dialo g box is only a vailable if y ou ha ve used the f ollowing t ext command:mesh/adapt/revert-to-R19.2-user-interface ; not e tha t if y ou r evert the user interface, you c annot undo it in the cur rent session, and some func tionalit y is no longer a vailable . Domain → Adapt → Mark/A dapt C ells → Region... Controls 3903Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonOptions contains r adio butt ons tha t control whether the c ells inside or outside the r egion ar e mar ked f or refinemen t. Inside enables the mar king of c ells with c entroids tha t are within the r egion. Outside enables the mar king of c ells with c entroids tha t are outside the r egion. Shap es contains r adio butt ons tha t control the t ype of r egion. Hex/Q uad defines a he xahedr al region in 3D or a r ectangular r egion in 2D .The appr opriate butt on will app ear for the solv er you ar e using . Spher e/Circle defines a spher ical region in 3D or a cir cular r egion in 2D .The appr opriate butt on will app ear f or the solv er you ar e using . Cylinder defines a c ylindr ical region in 3D or a r ectangular r egion in 2D . Manage ... opens the Manage A daption R egist ers D ialog Box (p.3848 ), which allo ws you t o displa y and manipula te adaption r egist ers tha t are gener ated using the Mark command . Controls... opens the Mesh A daption C ontrols D ialog Box (p.3851 ), which allo ws you t o control certain asp ects of the adaption pr ocess. Input C oordina tes defines the e xtent of the selec ted r egion. The app earance of this b ox changes dep ending on the t ype of region selec ted. If the r egion selec ted is a he xahedr on or quadr ilateral, you will sp ecify the minimum and maximum coordina tes defining the b ox. (The Radius real numb er field will not b e ac tive.) X M in,Y M in, Z M in define the c oordina tes of the minimum p oint defining the he xahedr on or r ectangle . For quadr ilaterals, the Z M in real en try field will not b e ac tive. X M ax,Y M ax, Z M ax define the c oordina tes of the maximum p oint defining the he xahedr on or r ectangle . For quadr ilaterals, the Z M ax real en try field will not b e ac tive. If the r egion selec ted is a spher e or cir cle, you will sp ecify the c oordina tes of the spher e’s center and its r adius . (The maximum c oordina te real numb er fields will not b e ac tive.) X Center,Y Center, Z C enter are the c oordina tes of the c entroid of the spher e or cir cle. For cir cles, the Z Center real en try field will not b e ac tive. Radius is the r adius of the spher e or cir cle. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3904Ribbon R eference GuideIf the r egion selec ted is a c ylinder , you will sp ecify the minimum and maximum c oordina tes defining the c ylinder axis , as w ell as the r adius of the c ylinder . X-A xis M in,Y-A xis M in, Z-A xis M in define the c oordina tes of the minimum p oint defining the c ylinder axis . For 2D c ases , the Z-A xis M in real en try field will not b e ac tive. X-A xis M ax,Y-A xis M ax, Z-A xis M ax define the c oordina tes of the maximum p oint defining the c ylinder axis . For 2D c ases , the Z-A xis M ax real en try field will not b e ac tive. Radius is the r adius of the c ylinder . (In 2D , this will b e the width of the r esulting r ectangle .) Selec t Points with M ouse allows you t o selec t specify c oordina tes with the mouse . If one of the mouse butt ons is defined as a mouse probe, you ma y selec t the input c oordina tes fr om a displa y of the mesh or solution field . For mor e inf orm- ation on mouse butt ons, refer to Controlling the M ouse B utton F unctions (p.2833 ). After you selec t the points, the v alues will b e loaded aut oma tically in to the appr opriate real numb er field .You ha ve the option of editing these v alues b efore mar king or adapting .The or der of input f or defining a he xahedr on (r ectangle) is insignific ant, but the or der of input f or the spher e (cir cle) has signific ance. First, you selec t the lo cation of the c entroid.Then y ou selec t a p oint tha t lies on the spher e, tha t is, a point tha t is one r adius a way from the c entroid. Adapt adapts the mesh based on the r egion defined and the in/out option. Mark mar ks the c ells t o be refined based on the r egion defined and the in/out option. This c ommand pr oduces an adaption r egist er. 48.2.77. Replac e Cell Z one D ialo g Box The Replac e Cell Z one dialo g box allo ws you t o replac e a single c ell z one or multiple z ones . See Re- placing Z ones (p.815) for details . Domain → Zones → Replac e Zone ... 3905Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonControls Case/M esh F ile allows you t o sp ecify a mesh file fr om which y ou w ant to replac e the z one . Existing Z ones contains a list of c ell z ones fr om which y ou c an selec t the z one t o be replac ed. Replac e with contains a list of c ell z ones fr om which y ou c an selec t the z one t o replac e the z one selec ted in Existing Zones list. Interpolate Data allows you t o enable/disable da ta in terpolation if da ta alr eady exists . Replac e replac es the selec ted c ell z one . 48.2.78. Rep ort Definitions D ialo g Box Solution → Rep orts → Definitions → Edit... For inf ormation on cr eating r eport definitions , see Monit oring and R eporting S olution D ata (p.2910 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3906Ribbon R eference GuideControls Rep ort Definitions lists all of the e xisting r eport definitions . New drop-do wn list allo wing y ou t o create new r eport definitions (sur face, volume , force, flux, dpm, and user- defined). Edit... allows you t o edit the pr operties of the selec ted r eport definition. Delet e delet es the selec ted r eport definition. Comput e comput es the v alue of the selec ted r eport definition and pr ints to the c onsole . Create Output P aramet er creates an output par amet er for the selec ted r eport definition(s) with the name -op . Used In lists the r eport files and r eport plots tha t contain the selec ted r eport definition. Edit... opens the r eport file/plot dialo g box for the r eport file/plot selec ted in the Used In list. Rep ort Definition P roperties displa ys the pr operties of the selec ted r eport definition in the Rep ort Definition list. Rep ort File D efinitions ... opens the Report File D efinitions D ialog Box (p.3907 ). Rep ort Plot D efinitions opens the Report Plot D efinitions D ialog Box (p.3909 ). 48.2.79. Rep ort File D efinitions D ialo g Box Solution → Rep orts → File... 3907Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonControls Rep ort Files lists all of the e xisting r eport files . New... opens the New R eport File D ialog Box (p.3873 ). Edit... allows you t o edit the pr operties of the selec ted r eport file in the Edit R eport File D ialog Box (p.3815 ). Delet e delet es the selec ted r eport file . Activate activates the selec ted (pr eviously deac tivated) r eport file f or wr iting dur ing the solution c alcula tion. Deac tivate deac tivates the wr iting of the selec ted r eport file dur ing the solution c alcula tion. Rep ort Definition lists the r eport definitions included in the selec ted r eport file . Rep ort File P roperties lists the pr operties of the selec ted r eport file . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3908Ribbon R eference Guide48.2.80. Rep ort Plot D efinitions D ialo g Box Solution → Rep orts → Plot... Controls Rep ort Plots lists all of the e xisting r eport plots . New... opens the New R eport Plot D ialog Box (p.3874 ). Edit... allows you t o edit the pr operties of the selec ted r eport plot in the Edit R eport Plot D ialog Box (p.3817 ). Delet e delet es the selec ted r eport plot. Activate activates the selec ted (pr eviously deac tivated) r eport plot f or plotting dur ing the solution c alcula tion. Deac tivate deac tivates the plotting of the selec ted r eport plot dur ing the solution c alcula tion. Rep ort Definition lists the r eport definitions included in the selec ted r eport plot. 3909Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonRep ort Plot P roperties lists the pr operties of the selec ted r eport plot. 48.2.81. Residual M onit ors D ialo g Box You c an use the Residual M onit ors dialo g box to control the r esidual inf ormation tha t Fluen t reports. See Monit oring R esiduals (p.2647 ) for details ab out the it ems b elow. Solution → Rep orts → Residuals ... Controls Options selec ts an y combina tion of the f ollowing metho ds for reporting r esiduals . See Printing and P lotting R e- siduals (p.2650 ) for details . Print to Console specifies whether or not t o pr int residuals in the t ext windo w af ter each it eration. Plot specifies whether or not t o plot r esiduals in the gr aphics windo w (with the windo w ID set in Windo w) after each it eration. See Plot P aramet ers (p.2654 ) for details . Windo w sets the windo w ID in which the plot will b e dr awn. When ANSY S Fluen t is it erating , the ac tive graphics windo w is t emp orarily set t o this windo w to up date the r esidual plot , and then r etur ned t o its pr evious v alue .Thus, the r esidual plot c an b e main tained in a separ ate windo w tha t do es not in- terfere with other gr aphic al postpr ocessing . Iterations t o Plot is the numb er of hist ory points to displa y on the r esidual plot. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3910Ribbon R eference GuideAxes... opens the Axes D ialog Box (p.3717 ), which allo ws you t o mo dify the a ttribut es of the ax es. Curves... opens the Curves D ialog Box (p.3720 ), which allo ws you t o mo dify the a ttribut es of the r esidual cur ves. Iteration t o Store sets the numb er of r esidual hist ory points to be stored in the da ta file . Due t o the c ompac tion algor ithm used , saving 1000 p oints do es not r esult in just the last 1000 it erations b eing sa ved; the hist ory reaches back quit e a bit fur ther than tha t, but do es not sa ve a p oint at every iteration. Further back in the it eration history, the spacing b etween sa ved it erations gr ows lar ger. See Storing R esidual Hist ory Points (p.2650 ) for details . Residual Values controls the nor maliza tion and sc aling of r esiduals . See Controlling N ormaliza tion and Sc aling (p.2651 ) for details . Normaliz e specifies whether or not t o nor maliz e the pr inted or plott ed r esidual f or each v ariable b y the v alue indic ated as the Normaliza tion F actor for tha t variable .The default Normaliza tion F actor is the maximum r esidual v alue af ter the first 5 it erations . This option is off b y default. Iterations sets the numb er of it erations f or which ANSY S Fluen t will sear ch for the lar gest r esidual t o nor maliz e by. (If the Normaliz e option is tur ned off , this it em will not b e editable .) Scale specifies whether or not t o pr int or plot sc aled r esiduals f or each v ariable .This option is on b y default. Comput e Local Sc ale comput es and st ores b oth the lo cally and globally sc aled r esiduals fr om subsequen t iterations , for the pur pose of r eporting .You will selec t the t ype of r esidual sc aling f orm the Rep orting Option drop- down list. See Definition of R esiduals f or the P ressur e-Based S olver (p.2647 ) and Definition of R esiduals for the D ensit y-Based S olver (p.2648 ) for mor e inf ormation. Rep orting Option gives y ou the choic e of plotting or pr inting t o the c onsole the global sc aling or local sc aling of r e- siduals . Convergenc e Criterion consists of f our options tha t are available f or check ing an equa tion f or convergenc e. absolut e is the default and is a vailable f or st eady-sta te cases .The r esidual (sc aled and/or nor maliz ed) of an equa tion a t an it eration is c ompar ed with a user-sp ecified v alue . If the r esidual is less than the user- specified v alue , tha t equa tion is deemed t o ha ve converged f or a time st ep. relative is wher e the r esidual of an equa tion a t an it eration of a time st ep is c ompar ed with the r esidual a t the star t of the time st ep. If the r atio of the t wo residuals is less than a user-sp ecified v alue , tha t equa tion is deemed t o ha ve converged f or a time st ep. 3911Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonrelative or absolut e is wher e either the absolut e convergenc e criterion or the relative convergenc e criterion is met. At that point, the equa tion is c onsider ed c onverged . none is used t o disable c onvergenc e check ing. Convergenc e Conditions ... opens the Convergenc e Conditions D ialog Box (p.3793 ). Residual indic ates the name of each v ariable f or which r esidual inf ormation is a vailable . Monit or indic ates whether or not the r esiduals f or each v ariable ar e to be monit ored.You c an t oggle monit oring on and off f or each v ariable b y tur ning the c orresponding check b ox in the Monit or list on or off . Normaliza tion F actor shows the nor maliza tion fac tor for each v ariable .The default is the maximum r esidual v alue af ter the first 5 iterations .To set this v alue manually , enter a new v alue in the c orresponding Normaliza tion F actor field .This list will not app ear if the Normaliz e option is tur ned off . Check C onvergenc e indic ates whether or not the c onvergenc e of each v ariable is t o be monit ored. If convergenc e is b eing monit ored, the solution will st op aut oma tically when each v ariable meets its sp ecified c onvergenc e cri- terion. You c an check c onvergenc e only f or v ariables f or which y ou ar e monit oring r esiduals .You c an toggle c onvergenc e check ing on and off f or each v ariable b y tur ning the c orresponding check b ox in the Check C onvergenc e list on or off . Absolut e Criteria, Rela tive Criteria shows the r esidual v alue f or which the solution of each v ariable will b e consider ed t o be converged .To set this v alue manually , enter a new v alue in the c orresponding Absolut e Criteria/Rela tive Criteria field . Plot displa ys the cur rent residual hist ory plot. Renor maliz e sets the nor maliza tion fac tors t o the maximum v alues in the r esidual hist ories.Renor maliz e should b e used t o renor maliz e the r esidual plot in c ases wher e the maximum r esiduals o ccur sometime af ter the first fiv e iterations . 48.2.82. Rota te M esh D ialo g Box The Rota te M esh dialo g box allo ws you t o rotate the mesh ab out the r equir ed axis and r otation or igin by sp ecifying the angle of r otation. See Rotating the M esh (p.825) for details . Domain → Mesh → Transf orm → Rota te... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3912Ribbon R eference GuideControls Rota tion A ngle is the angle with which y ou w ant to rotate the mesh. You c an en ter a p ositiv e or nega tive real numb er. Rota tion Or igin defines the new or igin f or the mesh r otation. Rota tion A xis defines the axis ab out which y ou w ant to rotate the mesh. Domain E xtents displa ys the C artesian c oordina te extremes of the no des in the mesh. (These v alues ar e not editable; the y are pur ely inf ormational.) Rota te adds the sp ecified r otation par amet ers t o the appr opriate Cartesian c oordina te of e very no de in the mesh. 48.2.83. S2S Inf ormation D ialo g Box The S2S Inf ormation dialo g box allo ws you t o report values of the view fac tor and r adia tion emitt ed from one z one t o an y other z one . See Reporting R adia tion in the S2S M odel (p.1539 ) for details ab out the it ems b elow. Results → Model S pecific → S2S Inf ormation... 3913Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonControls Rep ort Options contains it ems f or which inf ormation is a vailable f or reporting . View Factors turns on the c omputa tion of view fac tors fr om one z one t o the other . Inciden t Radia tion turns on the c omputa tion of the inciden t radia tion fr om one z one t o the other . Boundar y Types contains a selec table list of t ypes of b oundar y zones . If you selec t (or deselec t) an it em in this list , all z ones of tha t type will b e selec ted (or deselec ted) aut oma tically in the From and To lists . From contains a selec table list of b oundar y zones f or which y ou w ould lik e da ta reported fr om the selec ted zone . To contains a selec table list of b oundar y zones f or which y ou w ould lik e da ta reported t o the selec ted z one . Comput e comput es the view fac tors and/or inciden t radia tion on the selec ted z ones . Write... opens The S elec t File D ialog Box (p.569), which y ou c an use t o sa ve the da ta as an S2S Inf o File (.sif format). 48.2.84. Separ ate Cell Z ones D ialo g Box The Separ ate Cell Z ones dialo g box allo ws you t o separ ate a single c ell z one in to multiple z ones of the same t ype. See Separ ating Z ones (p.804) for details . Domain → Zones → Separ ate → Cells ... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3914Ribbon R eference GuideControls Options specifies the metho d on which the c ell-z one separ ation is t o be based . Mark indic ates tha t the c ell z one is t o be separ ated based on the mar ks st ored in c ell r egist ers. Region indic ates tha t the c ell z one is t o be separ ated in to two or mor e contiguous r egions based on an in- ternal b oundar y within the or iginal z one . Regist ers contains a list of defined c ell r egist ers. If you ar e separ ating the c ell z one b y mar k, selec t the c ell regist er to be used in the Regist ers list. When the separ ation is p erformed , cells tha t are mar ked will b e plac ed in to a new z one . Zones contains a list of c ell z ones fr om which y ou c an selec t the z one t o be separ ated. Separ ate separ ates the selec ted c ell z one based on the sp ecified par amet ers. Rep ort reports wha t the r esult of the separ ation will b e without ac tually separ ating the c ell z one . 48.2.85. Separ ate Face Zones D ialo g Box The Separ ate Face Zones dialo g box allo ws you t o separ ate a single fac e zone in to multiple z ones of the same t ype. See Separ ating Z ones (p.804) for details . Domain → Zones → Separ ate → Faces... 3915Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonControls Options specifies the metho d on which the fac e separ ation is t o be based . Angle indic ates tha t the fac e zone is t o be separ ated based on signific ant angle (sp ecified in the Angle field). Face indic ates tha t the fac e zone is t o be separ ated b y putting each fac e in the z one in to its o wn z one . Mark indic ates tha t the fac e zone is t o be separ ated based on the mar ks st ored in c ell r egist ers. Region indic ates tha t the fac e zone is t o be separ ated based on c ontiguous r egions . Regist ers contains a list of defined c ell r egist ers. If you ar e separ ating fac es b y mar k, selec t the c ell r egist er to be used in the Regist ers list. When the separ ation is p erformed , all fac es of c ells tha t are mar ked will b e plac ed in to a new fac e zone . Zones contains a list of fac e zones fr om which y ou c an selec t the z one t o be separ ated. Angle specifies the signific ant angle t o be used when y ou separ ate a fac e zone based on angle . Faces with normal v ectors tha t diff er b y an angle gr eater than or equal t o the sp ecified signific ant angle will b e plac ed in diff erent zones when the separ ation o ccurs . Separ ate separ ates the selec ted fac e zone based on the sp ecified par amet ers. Rep ort reports wha t the r esult of the separ ation will b e without ac tually separ ating the fac e zone . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3916Ribbon R eference Guide48.2.86. Set Injec tion P roperties D ialo g Box The Set Injec tion P roperties dialo g box allo ws you t o define the pr operties of an e xisting discr ete- phase injec tion (which w as cr eated in the Injec tions D ialog Box (p.3837 )). See Defining Injec tion P roper- ties (p.1969 ) for details ab out the it ems list ed in this sec tion. The Set Injec tion P roperties dialo g box is op ened fr om the Injec tions D ialog Box (p.3837 ). Controls Injec tion N ame sets the name of the injec tion. Injec tion Type contains a dr op-do wn list of the a vailable injec tion t ypes:single ,group ,cone ,surface,plain-or ifice- atomiz er,pressur e-swir l-atomiz er,air-blast-a tomiz er,flat-fan-a tomiz er,effervescent-atomiz er, and file. (cone is not a vailable in 2D .) These choic es ar e descr ibed in Injec tion Types (p.1944 ). Numb er of S treams indic ates the numb er of par ticle str eams in a group ,cone , or an y of the atomiz er injec tions . (This it em will not app ear f or single ,surface, or file injec tions .) 3917Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonRelease F rom S urfaces indic ates the sur face from which the par ticles in a surface injec tion will b e released . (This it em will app ear only f or a surface injec tion.) Particle Type specifies the par ticle t ype as Massless ,Iner t,Droplet ,Combusting , or Multic omp onen t.These t ypes are descr ibed in Particle Types (p.1947 ). Laws (not f or massless par ticles) c ontains inputs f or cust omiz ed par ticle la ws. Custom enables the sp ecific ation of cust omiz ed par ticle la ws and op ens the Custom La ws Dialog Box (p.3799 ). Material (not f or massless par ticles) indic ates the ma terial for the par ticles . If this is the first time y ou ha ve created a par ticle of this t ype, you c an cho ose fr om all of the ma terials b y copying them fr om the da tabase or creating them fr om scr atch, as discussed in Setting D iscrete-Phase P hysical Properties (p.2011 ) and descr ibed in detail in Using the Create/Edit M aterials Dialog Box (p.1081 ). Diamet er D istribution (not f or massless par ticles) allo ws you t o change fr om the default linear interpolation metho d used t o determine the siz e of the par ticles in a group injec tion, or the default unif orm metho d used t o det ermine the siz e of the par ticles in a surface injec tion, to the rosin-r ammler or rosin-r ammler-lo garithmic metho d.The R osin-R ammler metho d for det ermining the r ange of diamet ers is descr ibed in Using the Rosin-R ammler D iamet er D istribution M etho d (p.1963 ). Evaporating S pecies (for droplet par ticles) sp ecifies the gas-phase sp ecies cr eated b y the v aporization and b oiling la ws (la ws 2 and 3). Devolatilizing S pecies (for combusting par ticles) sp ecifies the gas-phase sp ecies cr eated b y the de volatiliza tion la w (la w 4). This it em will not app ear f or two-mix ture-fraction non-pr emix ed c ombustion c alcula tions . Devolatilizing S tream (for combusting par ticles) sp ecifies the destina tion str eam f or the gas-phase sp ecies cr eated b y the de- volatiliza tion la w (la w 4). This it em will app ear only f or two-mix ture-fraction non-pr emix ed c ombustion c alcula tions . Oxidizing S pecies (for combusting par ticles) sp ecifies the gas phase sp ecies tha t par ticipa tes in the sur face char c ombustion reaction (la w 5). Produc t Species (for combusting par ticles) sp ecifies the gas-phase sp ecies cr eated b y the sur face char c ombustion r eaction (law 5). This it em will not app ear f or two-mix ture-fraction non-pr emix ed c ombustion c alcula tions . Produc t Stream (for combusting par ticles) sp ecifies the destina tion str eam f or the gas-phase sp ecies cr eated b y the sur face char c ombustion r eaction (la w 5). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3918Ribbon R eference GuideThis it em will app ear only f or two-mix ture-fraction non-pr emix ed c ombustion c alcula tions . Discr ete Phase D omain is available when using the Dense D iscr ete Phase M odel, descr ibed in Including the D ense D iscrete Phase M odel (p.2236 ). DEM C ollision P artner is available when using the DEM C ollision mo del, descr ibed in Modeling C ollision U sing the DEM M od- el (p.1930 ). Point Properties displa ys the inputs f or the p oint properties f or the injec tion (f or e xample , position, velocity, diamet er, temp erature, mass flo w rate, and stagger options). These inputs ar e descr ibed f or each injec tion t ype in Point Properties f or S ingle Injec tions (p.1948 ) – Point Properties f or E ffervescent Atomiz er Injec tions (p.1960 ). Stagger Options allows you t o set the stagger options: Stagger P ositions enables injec tion-sp ecific spa tial stagger ing of the par ticles . Stagger R adius specifies the r egion fr om which par ticles ar e released .This it em is a vailable only f or non-a tomiz er injec tions . First P oint specifies the first p oint properties f or the injec tion. This it em app ears only f or gr oup injec tions . Last P oint specifies the last p oint properties f or the injec tion. This it em app ears only f or gr oup injec tions . Update Injec tion D ispla y applies the cur rent point property settings t o the injec tion gr aphics windo ws so tha t you c an pr eview the eff ect of mo dified settings b efore sa ving the injec tion. This it em is not a vailable f or sur face, file, and c ondensa te injec tion t ypes. Physical M odels displa ys the inputs f or injec tion-sp ecific ph ysics mo dels . Drag P aramet ers allows the setting of the dr ag la w used in c alcula ting the f orce balanc e on the par ticles . See Particle Force Balanc e in the Theor y Guide for details on the it ems b elow. Drag L aw is a dr op-do wn list c ontaining the a vailable choic es for the dr ag la w: spher ical assumes tha t the par ticles ar e smo oth spher es. nonspher ical assumes tha t the par ticles ar e not spher es, but ar e all iden tically shap ed.The shap e is sp ecified by the Shap e Factor. 3919Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonStokes-C unningham is for use with sub-micr on par ticles . A Cunningham C orrection is added t o Stokes’ drag la w to det ermine the dr ag. high-M ach-numb er is similar t o the spher ical la w with c orrections t o acc oun t for a par ticle M ach numb er gr eater than 0.4 or a par ticle R eynolds numb er gr eater than 20. Ishii-Z uber is used in gas-liquid flo ws.This dr ag la w is only a vailable if the magnitude and dir ection of the gr avity vector ar e sp ecified in the Operating C onditions dialo g box. See Ishii-Z uber D rag Model in the Fluent Theor y Guide for details . Grace is used in gas-liquid flo ws.This dr ag la w is only a vailable if the magnitude and dir ection of the gr avity vector ar e sp ecified in the Operating C onditions dialo g box. See Grace Drag Model in the Fluent Theor y Guide for details . dynamic-dr ag accoun ts for the eff ects of dr oplet dist ortion. This dr ag la w is a vailable only when one of the droplet br eakup mo dels is used in c onjunc tion with unst eady tracking. See Dynamic D rag Model Theor y in the Theor y Guide for details . Shap e Factor specifies the shap e of the par ticles when nonspher ical is selec ted as the Drag L aw ( in Equa tion 16.75 in the Theor y Guide ). It is the r atio of the sur face area of a spher e ha ving the same v olume as the par ticle t o the ac tual sur face area of the par ticle .The shap e fac tor v alue cannot b e gr eater than 1. Cunningham C orrection ( in Equa tion 16.78 in the Theor y Guide ) is used with S tokes’ drag la w to det ermine the force ac ting on the par ticles when the par ticles ar e sub-micr on siz e. It app ears when Stokes- Cunningham is selec ted as the Drag L aw. Particle Rota tion contains settings f or the mo deling of par ticle r otation when the Enable Rota tion check b ox is selec ted (see Wall-P article R eflec tion M odel Theor y in the Fluent Theor y Guide ). Rota tional D rag L aw is a dr op-do wn list of a vailable r otational dr ag la w mo dels: Dennis-et-al uses Equa tion 16.90 in the Fluent Theor y Guide to calcula te the r otational dr ag c oefficien t . none implies z ero torque , tha t is, it excludes the influenc e of the fluid on the r otational par ticle motion. Magnus Lif t Law is a dr op-do wn list of a vailable M agnus lif t law mo dels: Oesterle-Bui-D inh uses O esterle and B ui D inh’s formula tion ( Equa tion 16.18 in the Fluent Theor y Guide ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3920Ribbon R eference GuideTsuji-et-al is based on the par ticle spin r ate (Equa tion 16.19 in the Fluent Theor y Guide ). Rubino w-K eller uses a linear dep endenc e of the r otational lif t coefficien t on the spin r ate (Equa tion 16.21 in the Fluent Theor y Guide ). none implies tha t the M agnus lif t will not b e included in y our simula tion. Brownian M otion enables the inc orporation of the eff ects of B rownian motion. This option is a vailable only when the Energy equa tion is enabled (in the Models group) and the Stokes-C unningham drag la w is selec ted from the Drag L aw drop-do wn list. See Brownian F orce in the Theor y Guide for details . Break up contains par amet ers tha t control dr oplet br eakup and c ollision. (This sec tion of the dialo g box app ears only if Unstead y Track ing is enabled in the Discrete Phase M odel D ialog Box (p.3360 ).) Enable Br eak up enables br eakup f or this injec tion. Break up M odel is a dr op-do wn list c ontaining par amet ers tha t control dr oplet br eakup. (This it em app ears only if Enable Br eak up is selec ted.) TAB enables the Taylor A nalo gy Breakup ( TAB) mo del, which is applic able t o man y engineer ing sprays.This metho d is based up on Taylor’s analo gy between an oscilla ting and dist orting droplet and a spr ing mass sy stem. See Taylor A nalo gy Breakup ( TAB) M odel in the Theor y Guide for details . For the TAB mo del, you must sp ecify the f ollowing c onstan ts: y0 is the c onstan t in Equa tion 16.386 in the Theor y Guide . Break up P arcels is the numb er of child par cels the dr oplet is split in to, as descr ibed in Velocity of C hild Droplets in the Theor y Guide . Wave enables the Wave br eakup mo del, which c onsiders the br eakup of the injec ted liquid t o be induc ed b y the r elative velocity between the gas and liquid phases . See Wave Breakup M odel for details . For the Wave mo del, you must sp ecify the f ollowing c onstan ts: B0 is the c onstan t in Equa tion 16.413 in the Theor y Guide . B1 is the c onstan t in Equa tion 16.415 in the Theor y Guide . 3921Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonKHR T enables the Kelvin-H elmholtz R ayleigh-T aylor br eakup mo del, which c onsiders the t wo com- peting eff ects of aer odynamic br eakup and instabilities due t o dr oplet acc eleration. See KHR T Breakup M odel in the Theor y Guide for details . For the KHR T mo del, you must sp ecify the f ollowing c onstan ts: B0 is the c onstan t in Equa tion 16.413 in the Theor y Guide . B1 is the c onstan t in Equa tion 16.415 in the Theor y Guide . Ctau is the c onstan t in Equa tion 16.420 in the Theor y Guide . CRT is the c onstan t in Equa tion 16.421 in the Theor y Guide . CL is the c onstan t in Equa tion 16.416 in the Theor y Guide . SSD enables the st ochastic sec ondar y dr oplet br eakup mo del, wher e the pr obabilit y of br eakup is indep enden t of the par ent droplet siz e and the sec ondar y dr oplet siz e is sampled fr om an analytic al solution of the F okker-P lanck equa tion f or the pr obabilit y distr ibution. See Stochastic S econdar y Droplet (SSD) M odel in the Theor y Guide for details . For the SSD mo del, you must sp ecify the f ollowing c onstan ts: Critical We is the cr itical Weber numb er in Equa tion 16.422 in the Theor y Guide . Core B1 is B in Equa tion 16.423 in the Theor y Guide . Target Np is the a verage numb er in par cels f or daugh ter par cels. Xi is in Equa tion 16.424 in the Theor y Guide . Madabhushi Enables the M adabhushi br eakup mo del. This mo del is a vailable only with single , group , or cone (solid c one) injec tions . Solid c one injec tion is r ecommended . For mor e inf ormation ab out the M adabhushi br eakup mo del, see Madabhushi B reakup M odel in the Fluent Theor y Guide . For the Madabhushi mo del, you must sp ecify the f ollowing c onstan ts: B0 is the c onstan t in Equa tion 16.413 in the Theor y Guide .The r ecommended v alue is 2.44. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3922Ribbon R eference GuideB1 is the c onstan t in Equa tion 16.415 in the Theor y Guide .The r ecommended v alue is 10. Jet D iamet er is the no zzle or ifice exit diamet er. Ligamen t Factor Adjusts the diamet er of the child dr oplets ar ising fr om the c olumn br eakup mech- anism C0 is the c olumn br eakup time c onstan t.The v alue r ecommended f or the M adabhushi breakup mo del is 3.44. Turbulen t Dispersion displa ys the inputs f or st ochastic tr acking and cloud tr acking. Stochastic Track ing controls the st ochastic tr acking f or turbulen t flo ws. Stochastic tr acking includes the eff ect of turbulen t velocity fluc tuations on the par ticle tr ajec tories using the DR W mo del descr ibed in Stochastic Tracking in the Theor y Guide . See Stochastic Tracking (p.1978 ) for details ab out the it ems b elow. Discr ete Random Walk M odel includes the eff ect of instan taneous turbulen t velocity formula tions on the par ticle tr ajec tories through st ochastic metho d. Random E ddy Lif etime specifies tha t the char acteristic lif etime of the edd y is t o be random. Numb er of Tries controls the inclusion of turbulen t velocity fluc tuations . An input of 1 or gr eater tells ANSY S Fluen t to include turbulen t velocity fluc tuations in the particle f orce balanc e. Time Sc ale C onstan t is in Equa tion 16.24 in the Theor y Guide .The default is 0.15; if you use the RSM, a value of 0.3 is recommended . Cloud Track ing incorporates the eff ects of turbulen t disp ersion on the injec tion. For details on the f ollowing it ems , see Particle C loud Tracking in the Theor y Guide and Cloud Tracking (p.1980 ). Cloud M odel enables par ticle cloud tr acking. Min. Cloud D iamet er specifies the diamet er of the cloud in which the par ticles en ter the domain. Max. Cloud D iamet er specifies the maximum allo wed cloud diamet er. Parcel displa ys the inputs f or controlling the discr ete phase par cels. 3923Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonParcel D efinitions contains settings f or ho w par cels ar e defined Parcel Release M etho d specifies the metho d for releasing par cels. Available settings ar e standar d,constan t-numb er, constan t-mass , and constan t-diamet er. See Steady/Transien t Treatmen t of P articles (p.1918 ) for details ab out these settings . Wet C ombustion displa ys the inputs f or the w et combustion mo del. Wet C ombustion M odel allows the c ombusting par ticles t o include an e vaporating/b oiling ma terial. Liquid M aterial contains a dr op-do wn list of liquid ma terials tha t can b e chosen as the e vaporating/b oiling ma terial to be included with the c ombusting par ticles . Liquid F raction sets the v olume fr action of the liquid pr esen t in the par ticle . Comp onen ts displa ys the inputs f or Multic omp onen t for use in the definition of the par ticle injec tion. For details on the f ollowing it ems , see Vapor Liquid E quilibr ium Theor y in the Theor y Guide . Multic omp onen t Settings contains the multic omp onen t injec tions . Comp onen t specifies the c omp onen t tha t is a par t of the multic omp onen t species . Mass F raction specifies the mass fr action of the c omp onen t in a multic omp onen t species . Evaporating S pecies specifies the gas-phase sp ecies t o be evaporated. Evaporating S tream specifies the sour ce str eam fr om which the sp ecies will b e evaporated. UDF displa ys the inputs f or User-D efined F unc tions for use in the definition of the par ticle injec tion. For details about user-defined func tions , see the separ ate Fluen t Customiza tion M anual . Initializa tion contains a dr op-do wn list of a vailable user-defined func tions .The UDF tha t you cho ose will b e used to mo dify the injec tion pr operties a t the time the par ticles ar e injec ted in to the domain. Heat/M ass Transf er allows you t o selec t the user-defined func tion tha t defines the hea t or mass tr ansf er. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3924Ribbon R eference GuideMultiple Reac tions displa ys the inputs f or Multiple S urface Reac tions . See Particle Sur face Reactions (p.1661 ) for details ab out this mo del. Species M ass F ractions specify the c ombustible fr action of the c ombusting par ticle if y ou ha ve defined mor e than one par ticle surface sp ecies . See Using the M ultiple Sur face Reactions M odel f or D iscrete-Phase P article C ombus- tion (p.1662 ) for details . File... opens The S elec t File D ialog Box (p.569), in which y ou c an selec t a file c ontaining the injec tion definition (when file is selec ted as the Injec tion Type). 48.2.87. Set M ultiple Injec tion P roperties D ialo g Box The Set M ultiple Injec tion P roperties dialo g box allo ws you t o set pr operties tha t are common t o multiple injec tions . See Defining P roperties C ommon t o M ore than One Injec tion (p.1981 ) for details about the it ems b elow. The Set M ultiple Injec tion P roperties dialo g box is op ened fr om the Injec tions D ialog Box (p.3837 ). Controls 3925Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonInjec tions S etup contains a list of the c ategor ies of injec tion pr operties tha t you c an set f or the injec tions in the Injec tions list.These c ategor ies c orrespond t o the c ategor ies of inputs in the Set Injec tion P roperties D ialog Box (p.3917 ).When y ou selec t an it em in the Injec tions S etup list, the dialo g box will e xpand t o sho w the relevant inputs , which ar e the same as those in the Set Injec tion P roperties dialo g box. Injec tions displa ys an inf ormational list of the injec tions f or which y ou ar e setting c ommon pr operties.These ar e the injec tions tha t you selec ted in the Injec tions D ialog Box (p.3837 ). 48.2.88. Shell C onduc tion L ayers D ialo g Box The Shell C onduc tion L ayers dialo g box allo ws you t o define the shell c onduc tion settings f or either a single Wall dialo g box or all of the w alls selec ted in the Shell C onduc tion Z ones list of the Shell Conduc tion M anager D ialog Box (p.3927 ). See Shell C onduc tion (p.989) and Managing S hell C onduc tion Walls (p.1484 ) for details ab out the it ems b elow. The Shell C onduc tion L ayers dialo g box is op ened fr om either the Wall D ialog Box (p.3549 ) or the Shell C onduc tion M anager D ialog Box (p.3927 ). Controls Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3926Ribbon R eference GuideNumb er of S hell C onduc tion L ayers allows you t o define the numb er of la yers tha t mak e up the w all(s). Layer 1 ,Layer 2 ... allows you t o define the settings f or each la yer. Note tha t Layer 1 refers t o the la yer closest t o the fluid / solid adjac ent to the w all z one , and la yers with higher numb ers ar e fur ther a way. Thick ness sets the thick ness of the la yer for the c alcula tion of the shell ther mal r esistanc e. Each la yer must ha ve a nonz ero thick ness Material N ame sets the ma terial type for the la yer.The c onduc tivit y of the ma terial is used f or the c alcula tion of shell ther mal r esistanc e. Materials ar e defined using the Materials Task P age (p.3384 ). Heat Gener ation R ate sets the r ate of hea t gener ation in the la yer. Note tha t you ha ve the option of defining the hea t gen- eration r ate using a user-defined func tion (UDF) tha t utiliz es the DEFINE_PROFILE macr o; for mor e information on cr eating and using user-defined func tions , see the Fluen t Customiza tion M anual . 48.2.89. Shell C onduc tion M anager D ialo g Box The Shell C onduc tion M anager dialo g box allo ws you t o manage , define , and displa y shell c onduc tion zones all in one lo cation. See Managing S hell C onduc tion Walls (p.1484 ) for details ab out using the Shell C onduc tion M anager dialo g box. Physics → Model S pecific → Shell C onduc tion... Controls 3927Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonSelec t Zones contains the list of Shell C onduc tion Z ones and Wall Z ones . Shell C onduc tion Z ones contains a list of z ones with shell c onduc tion enabled . Wall Z ones contains a list of z ones without shell c onduc tion. , disables and enables shell c onduc tion f or a selec ted z one , respectively. Enable sa ving shell z ones t o case file enables F luen t to aut oma tically wr ites shell z ones in to .cas files . Displa y Zones displa ys the selec ted w alls in the gr aphics windo w. Note tha t you c an selec t walls with or without shell c onduc tion. The z ones will b e displa yed with diff erent colors dep ending on the option selec ted in Mesh C olors D ialog Box (p.3244 ) (acc essible fr om the Mesh D ispla y Dialog Box (p.3239 )). Settings ... opens the Shell C onduc tion La yers D ialog Box (p.3926 ), wher e you c an define the shell pr operties of the w alls selec ted in the Shell C onduc tion Z ones list. Read ... allows you t o define y our shell c onduc tion settings b y reading a CSV file . Write... allows you t o wr ite your sa ved shell c onduc tion settings t o a CSV file . 48.2.90. Structural P oint Surface Dialo g Box The Structural P oint Surface dialo g box allo ws you t o in teractively cr eate str uctural p oint sur faces (sur faces c ontaining a single da ta p oint). See Structural Point Sur faces (p.2737 ) for details ab out the items b elow. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3928Ribbon R eference GuideControls Options contains options r elated t o the p oint tool. See Using the P oint Tool (p.2736 ) for details ab out using this feature. Point Tool enables the p oint tool. Reset resets the p oint tool to its default p osition. Coordina tes designa tes the c oordina tes of the p oint in the sur face (x0,y0,z0). Selec t Point with M ouse allows you t o selec t the p oint with the mouse .You c an selec t a p oint by click ing on a lo cation in the active windo w with the mouse-pr obe butt on. (See Controlling the M ouse B utton F unctions (p.2833 ) for information ab out setting mouse butt on func tions .) New S urface Name designa tes the name of the new sur face.The default is the c oncatenation of the sur face type and an in teger which is the new sur face ID . Create creates the sur face. Manage ... opens the Surfaces D ialog Box (p.3933 ) in which y ou c an r ename and delet e sur faces and det ermine their sizes. 48.2.91. Surface M eshes D ialo g Box The Surface M eshes dialo g box allo ws you t o read the sur face meshes in ANSY S Fluen t (See Reading Surface M esh F iles (p.737) for details on r eading sur face meshes .) The Surface M eshes dialo g box is op ened fr om the Geometr y Based A daption D ialog Box (p.3830 ). 3929Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonControls Surfaces contains a list of the sur faces a vailable in the sur face mesh y ou r ead. You c an selec t/deselec t the sur faces list ed under Surfaces. Read ... opens the Selec t File dialo g box in which y ou c an selec t the sur face mesh y ou w ant to read. Delet e allows you t o delet e the selec ted sur faces under Surfaces area. Displa y allows you t o displa y the selec ted sur faces under Surfaces. 48.2.92. Surface Rep ort Definition D ialo g Box Solution → Rep orts → Definitions → New → Surface Rep ort Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3930Ribbon R eference GuideControls Options Per S urface specifies whether or not the chosen field v ariable is c alcula ted fr om all of the selec ted sur faces c om- bined (default) or individually on each of the selec ted sur faces. Average O ver (optional) To ha ve Fluen t calcula te a r unning a verage f or the Surface Rep ort Definition you c an enter a p ositiv e integer gr eater than 1 (the default) f or Average O ver. Specifying a numb er gr eater than 1 means that F luent will pr int, plot , and wr ite the r unning a verage value of the selec ted v ariable inst ead of the curr ent v alue of the same v ariable . The v alue r eported is a veraged o ver the last iterations/time st eps, wher e is y our sp ecified Av- erage O ver value .When the it eration/time st ep numb er is lo wer than , Fluent c alculat es the a v- erage of the a vailable v ariable v alues . 3931Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonRep ort Files lists all of the r eport files wher e you c an wr ite the r eport definition da ta. Rep ort Plots lists all of the r eport plots wher e you c an plot the r eport definition da ta (assuming this r eport has the same units as the other r eport definitions included in the selec ted r eport plot). Create Rep ort File creates a new r eport file tha t includes this r eport definition. Rep ort Plot creates a new r eport plot tha t includes this r eport definition. Frequenc y specifies ho w fr equen tly the r eport definition is wr itten, plott ed, or pr inted t o the c onsole . Print to Console prints the v alue of the r eport definition t o the c onsole . Create Output P aramet er creates an output par amet er for this r eport definition with the name - op. Rep ort Type selec ts the in tegration metho d used on the selec ted sur faces.The a vailable r eport types ar e the same as those in the Surface Integrals D ialog Box (p.3726 ). See Surface Integration (p.2947 ) for details . Custom Vectors allows you t o sp ecify a v ector if y ou selec ted Custom Vector B ased F lux,Custom Vector F lux or Custom Vector Weigh ted A verage from the Rep ort Type drop-do wn list. Field Variable contains a list of solution v ariables tha t can b e monit ored on the selec ted sur faces.This list will not b e available if y ou selec t Mass F low R ate or Volume F low R ate as the Rep ort Type. Phase contains a list of all of the phases in the pr oblem tha t you ha ve defined .This is a vailable when the VOF, mixture, or E uler ian multiphase mo del is enabled . Surfaces contains a selec table list of the cur rent sur faces. Highligh t Surfaces if enabled , this option displa ys the selec ted sur face(s) in the gr aphics windo w. New S urface is a dr op-do wn list butt on tha t contains a list of sur face options: Point opens the Point Sur face Dialog Box (p.3898 ). Line/R ake opens the Line/R ake Sur face Dialog Box (p.3847 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3932Ribbon R eference GuidePlane opens the Plane Sur face Dialog Box (p.3895 ). Quadr ic opens the Quadr ic Sur face Dialog Box (p.3899 ). Iso-S urface opens the Iso-Sur face Dialog Box (p.3842 ). Iso-C lip opens the Iso-C lip D ialog Box (p.3841 ). Structural P oint opens the Structural Point Sur face Dialog Box (p.3928 ). OK creates the r eport definition. Comput e comput es the v alue of the r eport definition a t the selec ted sur face(s) and pr ints to the c onsole . 48.2.93. Surfaces D ialo g Box The Surfaces dialo g box allo ws you t o in teractively gr oup , rename , and delet e sur faces and obtain information ab out their c omp onen ts. See Grouping , Editing , Renaming , and D eleting Sur faces (p.2755 ) for details ab out the it ems b elow. Controls Surfaces contains a list of e xisting sur faces fr om which y ou c an selec t the sur face(s) of in terest. 3933Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonName displa ys the name of the selec ted sur face.You c an edit the t ext field t o mo dify the sur face name . (If mor e than one sur face is selec ted, the name of the first one y ou selec ted will b e displa yed.) Surface Type displa ys the t ype of sur face tha t is selec ted (f or e xample ,zone-surf if one sur face is selec ted, or Mul- tiple Surfaces if mor e than one sur face is selec ted). Points, 0D F acets, 1D F acets, and 2D F acets displa y the numb er of p oints and fac ets in the selec ted sur face. If mor e than one sur face is selec ted, the sum o ver all selec ted sur faces is displa yed f or each quan tity. Note tha t if y ou w ant to check these sta tistics f or a sur face tha t was read fr om a c ase file , you will need t o first displa y it. Highligh t Surfaces when enabled highligh ts the sur faces (selec ted in the Surfaces dialo g box) in the gr aphics windo w. ID displa ys the ID of the selec ted sur face.You c annot change this v alue . UnGroup ungr oups the selec ted sur face.This butt on is a vailable only if the selec ted sur face was cr eated b y Group ing two or mor e sur faces together . Rename renames the selec ted sur face in Surfaces with the name sp ecified in Name .This butt on is a vailable when just one sur face is selec ted. (If two or mor e sur faces ar e selec ted, it b ecomes the Group butt on.) Group groups t wo or mor e selec ted sur faces and giv es the gr oup the name en tered in Name .This butt on r eplac es the Rename butt on when t wo or mor e sur faces ar e selec ted. Delet e delet es the selec ted sur face(s). 48.2.94. Thread C ontrol D ialo g Box The Thread C ontrol dialo g box allo ws you t o control the maximum numb er of thr eads on each machine , as descr ibed in Controlling the Threads (p.3095 ). Parallel → Gener al → Thread C ontrol... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3934Ribbon R eference GuideControls Maximum N umb er of S pawned Threads contains a list of options f or defining the maximum numb er of thr eads on each machine . Numb er of N ode P rocesses on M achine specifies tha t the maximum numb er of thr eads on each machine is equal t o the numb er of ANSY S Fluen t no de pr ocesses on each machine . Numb er of C ores on M achine specifies tha t the maximum numb er of thr eads on each machine is equal t o the numb er of c ores on the machine . ANSY S Fluen t obtains the numb er of c ores fr om the OS. Fixed N umb er specifies tha t the maximum numb er of thr eads tha t can b e spa wned on each machine is equal t o the numb er you pr ovide in the numb er-en try box below Fixed N umb er. 48.2.95. Transf orm S urface Dialo g Box The Transf orm S urface dialo g box allo ws you t o cr eate a new da ta sur face by rotating and/or tr ans- lating an e xisting sur face, and/or b y sp ecifying a c onstan t nor mal distanc e from it. See Transf orming Surfaces (p.2753 ) for details ab out the it ems b elow. Domain → Surface → Create → Transf orm... 3935Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonControls Rota te contains the tr ansf ormation par amet ers f or rotation. About defines the or igin ab out which the sur face is r otated.You will sp ecify a p oint, and the or igin of the coordina te sy stem f or the r otation will b e set t o the sp ecified p oint. For e xample , if you sp ecified the point (1,0) in 2D , rotation w ould b e ab out the axis anchor ed a t (1,0). You c an either en ter the p oint’s coordina tes in the x,y,z fields or click the Mouse S elec t butt on and selec t a p oint in the gr aphics windo w using the mouse . Angles define the angles ab out the x,y, and z axes (tha t is, the ax es of the c oordina te sy stem with the or igin defined under About) by which the sur face is r otated. For 2D pr oblems , you c an sp ecify r otation about the z axis only . Transla te contains the tr ansf ormation par amet ers f or tr ansla tion. x,y,z define the distanc e by which the sur face is tr ansla ted in each dir ection. Iso-D istanc e contains the tr ansf ormation par amet ers f or “isodistancing .” d sets the nor mal distanc e between the or iginal sur face and the tr ansf ormed sur face. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3936Ribbon R eference GuideTransf orm S urface contains a list of e xisting sur faces fr om which y ou c an selec t the sur face to be transf ormed .The selec ted surface will r emain unchanged; the tr ansf ormation will cr eate a new sur face. New S urface Name designa tes the name of the new sur face.The default is the c oncatenation of the tr ansf ormation t ype (tha t is, iso-distanc e, rotate, or tr ansla te) and an in teger which is the new sur face ID . Create creates the sur face. Manage ... opens the Surfaces D ialog Box (p.3933 ) in which y ou c an r ename and delet e sur faces and det ermine their sizes. 48.2.96. Transla te M esh D ialo g Box The Transla te M esh dialo g box allo ws you t o change the or igin of the mesh. See Transla ting the Mesh (p.824) for details . Domain → Mesh → Transf orm → Transla te... Controls Transla tion O ffsets contains the desir ed changes in the mesh c oordina tes (tha t is, the desir ed delta in the ax es or igin). You can en ter a p ositiv e or nega tive real numb er. X,Y,Z defines the deltas in the , , and directions , in the cur rent units of length. Domain E xtents displa ys the C artesian c oordina te extremes of the no des in the mesh. (These v alues ar e not editable; the y are pur ely inf ormational.) Xmin, Ymin, Zmin shows the minimum v alues of C artesian c oordina tes in the mesh. 3937Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonXmax, Ymax, Zmax shows the maximum v alues of C artesian c oordina tes in the mesh. Transla te adds the sp ecified tr ansla tion off sets t o the appr opriate Cartesian c oordina te of e very no de in the mesh. 48.2.97. Turb o 2D C ontours D ialo g Box The Turb o 2D C ontours dialo g box enables y ou t o displa y turb omachiner y-sp ecific c ontours of v ariables on sur faces of c onstan t pit chwise , spanwise , or mer idional c oordina tes, projec ted on to a plane . See Displa ying Turbomachiner y 2D C ontours (p.2894 ) for details . Results → Model S pecific → Turb o Topology → 2D C ontours ... Controls Turb o Topology contains a list of defined t opologies . Selec t from the list t o displa y the v alues f or the selec ted t opology. Options contains the check butt ons tha t set v arious c ontour displa y options . Filled toggles b etween filled c ontours and line c ontours . Node Values toggles b etween using sc alar field v alues a t no des and a t cell c enters f or computing the c ontours . Global R ange toggles b etween basing the minimum and maximum v alues on the r ange of v alues on the selec ted surfaces (off ), and basing them on the r ange of v alues in the en tire domain (on, the default). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3938Ribbon R eference GuideAuto Range toggles b etween aut oma tic and manual setting of the c ontour r ange . Any time y ou change the Contours of selec tion, Auto Range is reset t o on. Clip t o Range determines whether or not v alues outside the pr escr ibed Min/ Max range ar e contoured when using Filled contours . If selec ted, values outside the r ange will not b e contoured. If not selec ted, values below the Min value will b e color ed with the lo west c olor on the c olor sc ale, and v alues ab ove the Max value will b e color ed with the highest c olor on the c olor sc ale. See Specifying the R ange of Magnitudes D ispla yed (p.2789 ) for details . Levels sets the numb er of c ontour le vels tha t are displa yed. Setup indic ates the ID numb er of the c ontour setup . For fr equen tly used c ombina tions of c ontour fields and options , you c an st ore the inf ormation needed t o gener ate the c ontour plot b y sp ecifying a Setup numb er and setting up the desir ed inf ormation in the dialo g box. See Storing C ontour P lot S ettings (p.2791 ) for details . Contours of contains a list fr om which y ou c an selec t the sc alar field t o be contoured. Min shows the minimum v alue of the sc alar field . If Auto Range is off , you c an set the minimum b y typing a new v alue . Max shows the maximum v alue of the sc alar field . If Auto Range is off , you c an set the maximum b y typing a new v alue . Normalised S panwise C oordina tes (0 t o 1) enables y ou t o sp ecify the c oordina te for the spanwise sur face you w ant to create. Displa y draws the c ontours in the ac tive gr aphics windo w. Comput e calcula tes the sc alar field and up dates the Min and Max values (e ven when Auto Range is off ). 48.2.98. Turb o Averaged C ontours D ialo g Box The Turb o Averaged C ontours dialo g box enables y ou t o displa y turb omachiner y-sp ecific cir cumf er- entially a veraged c ontours of v ariables pr ojec ted on an - plane . See Displa ying Turbomachiner y Averaged C ontours (p.2892 ) for details . Results → Model S pecific → Turb o Topology → Averaged C ontours ... 3939Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonControls Turb o Topology contains a list of defined t opologies . Selec t from the list t o displa y the v alues f or the selec ted t opology. Options contains the check butt ons tha t set v arious c ontour displa y options . Filled toggles b etween filled c ontours and line c ontours . Auto Range toggles b etween aut oma tic and manual setting of the c ontour r ange . Any time y ou change the Contours of selec tion, Auto Range is reset t o on. Clip t o Range determines whether or not v alues outside the pr escr ibed Min/ Max range ar e contoured when using Filled contours . If selec ted, values outside the r ange will not b e contoured. If not selec ted, values below the Min value will b e color ed with the lo west c olor on the c olor sc ale, and v alues ab ove the Max value will b e color ed with the highest c olor on the c olor sc ale. See Specifying the R ange of Magnitudes D ispla yed (p.2789 ) for details . Levels sets the numb er of c ontour le vels tha t are displa yed. Setup indic ates the ID numb er of the c ontour setup . For fr equen tly used c ombina tions of c ontour fields and options , you c an st ore the inf ormation needed t o gener ate the c ontour plot b y sp ecifying a Setup numb er and setting up the desir ed inf ormation in the dialo g box. See Storing C ontour P lot S ettings (p.2791 ) for details . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3940Ribbon R eference GuideContours of contains a list fr om which y ou c an selec t the sc alar field t o be contoured. Min shows the minimum v alue of the sc alar field . If Auto Range is off , you c an set the minimum b y typing a new v alue . Max shows the maximum v alue of the sc alar field . If Auto Range is off , you c an set the maximum b y typing a new v alue . Domain M in shows the global minimum v alue of the sc alar field f or the en tire domain. Domain M ax shows the global maximum v alue of the sc alar field f or the en tire domain. Displa y draws the c ontours in the ac tive gr aphics windo w. Comput e calcula tes the sc alar field and up dates the Min and Max values (e ven when Auto Range is off ). 48.2.99. Turb o Averaged X Y Plot D ialo g Box The Turb o Averaged X Y Plot dialo g box enables y ou t o displa y da ta in an X Y plot f ormat as a func tion of either the mer idional or the spanwise c oordina te. See Gener ating A veraged X Y Plots of Turboma- chiner y Solution D ata (p.2896 ) for details . Results → Model S pecific → Turb o Topology → Averaged X Y Plot... Controls Y Axis F unc tion contains a list of solution v ariables tha t can b e used f or the axis of the plot. 3941Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonMin shows the minimum v alue of the sc alar field . Max shows the maximum v alue of the sc alar field . Turb o Topology contains a list of defined t opologies . Selec t from the list t o displa y the v alues f or the selec ted t opology. X Axis F unc tion enables y ou t o selec t the c oordina te to be used f or the axis of the plot. The choic es ar e Hub t o Casing Distanc e (spanwise c oordina te), and Meridional D istanc e (mer idional c oordina te). Fractional D istanc e sets a fr actional v alue (0 t o 1) f or either the spanwise Hub t o Casing distanc e or the mer idional Inlet t o Outlet distanc e, dep ending on y our selec tion f or X Axis F unc tion . Write to File enables the file-wr iting option. When this option is selec ted, the Plot butt on will change t o Write.... Clicking on the Write... butt on will op en The S elec t File D ialog Box (p.569), in which y ou c an sp ecify a name and sa ve a file c ontaining the plot da ta.The format of this file is descr ibed in XY Plot F ile Format (p.2874 ). Plot plots the sp ecified sur face and/or file da ta in the ac tive gr aphics windo w using the cur rent axis and cur ve attribut es. If the Write to File option is tur ned on, this butt on b ecomes the Write... butt on. Write... opens The S elec t File D ialog Box (p.569), in which y ou c an sa ve the plot da ta to a file .This butt on r eplac es the Plot butt on when the Write to File option is tur ned on. Comput e calcula tes the sc alar field and up dates the Min and Max values . Axes... opens the Axes D ialog Box (p.3717 ), which enables y ou t o cust omiz e the plot ax es. Curves... opens the Curves D ialog Box (p.3720 ), which enables y ou t o cust omiz e the cur ves used in the X Y plot. 48.2.100. Turb o Options D ialo g Box The Turb o Options dialo g box enables y ou t o globally set the turb omachiner y topology for y our model. See Globally S etting the Turbomachiner y Topology (p.2897 ) for details . Results → Model S pecific → Turb o Topology → Options ... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3942Ribbon R eference GuideControls Current Topology contains a list of pr edefined turb o topologies . 48.2.101. Turb o Rep ort Dialo g Box The Turb o Rep ort dialo g box allo ws you t o calcula te turb omachiner y-sp ecific quan tities and in tegrals. See Gener ating R eports of Turbomachiner y Data (p.2884 ) for details . Results → Model S pecific → Turb o Topology → Rep ort... Controls Inlet/Outlet D ata contains quan tities tha t can b e calcula ted a t inlets and outlets . 3943Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonAverages allows you t o cho ose b etween Mass-W eigh ted and Area-W eigh ted averages f or all applic able comput ed quan tities .These quan tities ar e calcula ted f or the Inlet and Outlet topologies wher e ap- plicable . Turb o Topology contains a list of defined t opologies . Selec t from the list t o displa y the v alues f or the selec ted t opology. Mass F low is the mass flo w rate thr ough a sur face as defined in Equa tion 40.2 (p.2885 ). Swirl Numb er is the swir l numb er as defined in Equa tion 40.3 (p.2886 ). Average Total P ressur e is the ar ea-a veraged or mass-a veraged t otal pr essur e as defined in Equa tion 40.4 (p.2886 ) or Equa- tion 40.5 (p.2886 ). Average Total Temp erature is the ar ea-a veraged or mass-a veraged t otal t emp erature as defined in Equa tion 40.6 (p.2886 ) or Equa tion 40.7 (p.2887 ). Average R adial F low A ngle is the ar ea-a veraged or mass-a veraged r adial flo w angle as defined in Equa tion 40.8 (p.2887 ) or Equa- tion 40.10 (p.2887 ). Average Theta F low A ngle is the ar ea-a veraged or mass-a veraged tangen tial flo w angle as defined in Equa tion 40.9 (p.2887 ) or Equa tion 40.11 (p.2887 ). Losses contains the v alues of loss-r elated c oefficien ts. Engr. Passage L oss C oef is the engineer ing loss c oefficien t as defined in Equa tion 40.12 (p.2888 ). Norm. Passage L oss C oef is the nor maliz ed loss c oefficien t as defined in Equa tion 40.13 (p.2888 ). Forces contains the axial f orce and the t orque on the r otating par ts. Axial F orce is the axial f orce on the r otating par ts as defined in Equa tion 40.14 (p.2888 ). Torque is the t orque on the r otating par ts as defined in Equa tion 40.15 (p.2888 ). Efficiencies contains the v alues of isen tropic , polytr opic and h ydraulic efficiencies . Isen tropic is the isen tropic efficienc y for a c ompr essor or a turbine (mot or) c alcula ted in the pr esenc e of a compr essible w orking fluid as defined in Equa tion 40.20 (p.2890 ) or Equa tion 40.26 (p.2892 ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3944Ribbon R eference GuidePolytr opic is the p olytr opic efficienc y for a c ompr essor or a turbine (mot or) c alcula ted in the pr esenc e of a compr essible w orking fluid as defined in Equa tion 40.21 (p.2890 ) or Equa tion 40.27 (p.2892 ). Hydraulic is the h ydraulic efficienc y for a pump or a h ydraulic turbine (mot or) c alcula ted in the pr esenc e of an incompr essible w orking fluid as defined in Equa tion 40.16 (p.2889 ) or Equa tion 40.22 (p.2891 ). Comput e starts the c alcula tion of the quan tities in all the fields in the Turb o Rep ort dialo g box. Note tha t this process ma y tak e some time f or a lar ge pr oblem. Write... opens the Selec t File dialo g box, which y ou c an use t o sa ve the r eported v alues t o a file . 48.2.102. Turb o Topology Dialo g Box The Turb o Topology dialo g box allo ws you t o define the t opology for a turb omachiner y applic ation, so tha t you c an use the turb omachiner y-sp ecific p ostpr ocessing f eatures descr ibed in Turbomachiner y Postpr ocessing (p.2881 ). See Defining the Turbomachiner y Topology (p.2881 ) for details ab out the it ems below. Domain → Mesh M odels → Turb o Topology... Controls 3945Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonTurb o Topology Name specifies the name of the new t opology. Boundar ies contains r adio butt ons f or the t opology boundar ies t o be defined . Hub specifies the definition f or the w all z one(s) f orming the lo wer b oundar y of the flo w passage (gener ally toward the axis of r otation of the machine). Casing specifies the definition of the w all z one(s) f orming the upp er b oundar y of the flo w passage (a way from the axis of r otation of the machine). Theta P eriodic specifies the definition of the p eriodic b oundar y zone(s) on the cir cumf erential b oundar ies of the flow passage . Theta M in,Theta M ax specify the definition of the w all z ones a t the minimum and maximum angular ( ) positions on a cir- cumf erential b oundar y. Inlet specifies the definition of the inlet z one(s) thr ough which the flo w en ters the passage . Outlet specifies the definition of the outlet z one(s) thr ough which the flo w exits the passage . Blade specifies the definition of the w all z one(s) tha t defines the blade(s) (if an y). Note tha t these z ones cannot b e attached t o the cir cumf erential b oundar ies. For this situa tion, use Theta M in and Theta Max to define the blade . Surfaces contains a selec table list of the a vailable sur faces, from which y ou c an selec t the sur face(s) tha t represen t the b oundar y selec ted under Boundar ies. Define defines the new t opology. If you ha ve selec ted an e xisting t opology the Define butt on is r eplac ed b y the Modify butt on. Displa y draws the defined t opology in the ac tive gr aphics windo w. 48.2.103. UDF Libr ary M anager D ialo g Box The UDF Libr ary M anager dialo g box allo ws you t o load/unload the user-defined func tion libr aries. See the separ ate Fluen t Customiza tion M anual for details . User D efined → User D efined → Func tions → Manage ... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3946Ribbon R eference GuideControls UDF Libr aries lists the user-defined func tion libr aries tha t are loaded in ANSY S Fluen t. Libr ary Name specifies the name of the libr ary to be loaded/unloaded . Load opens the sp ecified libr ary and loads the user-defined func tion. Unload unloads the sp ecified libr ary. 48.2.104. User-D efined F an M odel D ialo g Box The User-D efined F an M odel dialo g box allo ws you t o periodically r egener ate a pr ofile file tha t can be used t o sp ecify the char acteristics of a fan, including pr essur e jump acr oss the fan, and r adial and swir ling c omp onen ts of v elocity gener ated b y the fan. See User-D efined F an M odel (p.1043 ) for details about this f eature and ho w to use this dialo g box. User D efined → Model S pecific → Fan M odel... 3947Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonControls Fan Z ones contains a list fr om which y ou c an selec t the fan z one(s) on which y our e xecutable will op erate. Iteration U pdate In terval specifies ho w of ten the e xecutable will b e called on t o up date the fan pr ofile file . Output P rofile P oints specifies the numb er of p oints in the pr ofile file t o be wr itten b y ANSY S Fluen t. External C ommand N ame specifies the name of the e xecutable . 48.2.105. User-D efined F unc tion H ooks D ialo g Box The User-D efined F unc tion H ooks dialo g box allo ws you t o sp ecify user-defined func tions (UDFs) connec ted t o a numb er of mo dels and pr ocedur es in ANSY S Fluen t. See the separ ate Fluen t Custom- ization M anual for details . Imp ortant You c an ho ok multiple UDFs t o the f ollowing func tions: •Controls •Initializa tion •Adjust •Execut e At End Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3948Ribbon R eference Guide•Read C ase •Write Case •Read D ata •Write Data •Execut e at Exit User D efined → User D efined → Func tion H ooks ... Controls Initializa tion selec ts a UDF tha t is c alled immedia tely af ter you initializ e your flo w field . Adjust selec ts a UDF tha t is c alled a t the b eginning of an it eration b efore solution of v elocities , pressur e, and other quan tities b egins . 3949Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonExecut e At End selec ts a UDF tha t is c alled a t the end of an it eration or time-st ep. Read C ase selec ts a UDF tha t defines a cust omiz ed sec tion tha t is t o be read fr om the c ase file . Write Case selec ts a UDF tha t defines a cust omiz ed sec tion tha t is t o be wr itten t o the c ase file . Read D ata selec ts a UDF tha t defines a cust omiz ed sec tion tha t is t o be read fr om the da ta file . Write Data selec ts a UDF tha t defines a cust omiz ed sec tion tha t is t o be wr itten t o the da ta file . Execut e at Exit selec ts a UDF tha t is c alled when e xiting an ANSY S Fluen t session. Wall H eat Flux selec ts a UDF tha t mo difies the w ay tha t the solv er comput es the hea t flux b etween a w all and the neighb oring fluid c ells. Net Reac tion R ate selec ts a UDF tha t defines the net r eaction r ate. Volume Reac tion R ate selec ts a UDF tha t defines a v olumetr ic reaction r ate. Surface Reac tion R ate selec ts a UDF tha t defines a sur face reaction r ate. Particle Reac tion R ate selec ts a UDF tha t defines a par ticle r eaction r ate. Turbulen t Premix ed S our ce selec ts a UDF tha t defines the turbulen t flame sp eed and sour ce term for the pr emix ed or par tially pr emix ed combustion mo del. Chemistr y Step selec ts a UDF tha t defines the chemistr y step func tion. Spray Collide selec ts a UDF tha t defines the spr ay collide func tion. Cavita tion M ass R ate selec ts a UDF tha t defines the c avitation r ate. DO S our ce selec ts a UDF tha t defines the discr ete or dina te sour ce func tion. DO D iffuse Reflec tivit y selec ts a UDF tha t defines the diffuse r eflec tivit y func tion f or the DO r adia tion mo del. DO S pecular Reflec tivit y selec ts a UDF tha t defines the sp ecular r eflec tivit y func tion f or the DO r adia tion mo del. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3950Ribbon R eference GuideEmissivit y Weigh ting F actor selec ts a UDF tha t defines the emissivit y weigh ting fac tor for the non-gr ay DO r adia tion mo del or the non-gr ay P-1 r adia tion mo del. Thick ened F lame M odel P aramet ers selec ts a UDF tha t defines the par amet ers f or the Thick ened F lame M odel. 48.2.106. User-D efined M emor y Dialo g Box The User-D efined M emor y dialo g box allo ws you t o allo cate memor y for user-defined st orage v ariables . See the separ ate Fluen t Customiza tion M anual for details . User D efined → User D efined → Memor y... Controls Numb er of U ser-D efined M emor y Locations specifies the numb er of memor y locations t o be allo cated. Numb er of U ser-D efined N ode M emor y Locations specifies the numb er of no de memor y locations t o be allo cated. Imp ortant For p ostpr ocessing User-D efined M emor y in CFD-P ost, the ANSY S Fluen t user must selec t the UDM quan tities using the Data F ile Q uan tities option and subsequen tly wr ite the da ta file t o postpr ocess the quan tities in ANSY S Fluen t. Alternatively, you ha ve the option of exporting the desir ed quan tities t o a .cdat file.This will ensur e tha t all the UDM quan tities are available f or p ostpr ocessing in CFD-P ost. Refer to the ANSY S CFD-P ost manual f or mor e information. 48.2.107. User D efined Rep ort Definition D ialo g Box Solution → Rep orts → Definitions → New → User D efined ... or Solution → Rep ort Definitions New → User D efined 3951Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonControls Func tion drop-do wn list wher e you c an selec t the func tion tha t you loaded f or this r eport definition. Average O ver (optional) To ha ve Fluen t calcula te a r unning a verage f or the User D efined Rep ort Definition you c an enter a p ositiv e integer gr eater than 1 (the default) f or Average O ver. Specifying a numb er gr eater than 1 means that F luent will pr int, plot , and wr ite the r unning a verage value of the selec ted v ariable inst ead of the curr ent v alue of the same v ariable . The v alue r eported is a veraged o ver the last iterations/time st eps, wher e is y our sp ecified Average Over value .When the it eration/time st ep numb er is lo wer than , Fluent c alculat es the a verage of the available v ariable v alues . Rep ort Files lists all of the r eport files wher e you c an wr ite the r eport definition da ta. Rep ort Plots lists all of the r eport plots wher e you c an plot the r eport definition da ta (assuming this r eport has the same units as the other r eport definitions included in the selec ted r eport plot). Create Rep ort File creates a new r eport file tha t includes this r eport definition. Rep ort Plot creates a new r eport plot tha t includes this r eport definition. Frequenc y specifies ho w fr equen tly the r eport definition is wr itten, plott ed, or pr inted t o the c onsole . Print to Console prints the v alue of the r eport definition t o the c onsole . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3952Ribbon R eference GuideCreate Output P aramet er creates an output par amet er for this r eport definition with the name - op. 48.2.108. User-D efined Sc alars D ialo g Box The User-D efined Sc alars dialo g box allo ws you t o include user-defined sc alar tr ansp ort equa tions in your c alcula tion. See User-D efined Sc alar (UDS) Transp ort Equa tions (p.1197 ) for details . User D efined → User D efined → Scalars ... Controls Numb er of U ser-D efined Sc alars specifies ho w man y additional sc alar tr ansp ort equa tions y ou w ould lik e to include in the c alcula tion. Inlet D iffusion when enabled allo ws you t o include the diffusion t erm in the UDS tr ansp ort equa tion f or all inflo w and outflo w boundar ies. User-D efined Sc alars Options contains settings tha t define the sc alar tr ansp ort equa tion. UDS Inde x when set t o mar ks the first user-defined sc alar equa tion. Solution Z ones specifies in which z one the sc alar equa tion will b e solv ed:all fluid z ones ,all solid z ones ,all z ones (fluid and solid) or selec ted z ones . Flux F unc tion is a dr op-do wn list c ontaining a vailable func tions f or the c onvection t erm of the user-defined sc alar transp ort equa tion(s). 3953Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonnone (the default) indic ates tha t ther e is no c onvection t erm included in the sc alar tr ansp ort equa tion(s); that is, you w ant to solv e a P oisson equa tion inst ead of a c onvection/diffusion equa tion. mass flo w rate indic ates tha t the c onvection t erm in the sc alar tr ansp ort equa tion(s) is equal t o the mass flo w rate . Note tha t the none and mass flo w rate options will apply t o all solv ed user-defined sc alars . A user-defined flux func tion must b e supplied if a diff erent convective flux is desir ed f or each user-defined sc alar. Unstead y Func tion is a dr op-do wn list c ontaining a vailable func tions f or the unst eady term of the user-defined sc alar transp ort equa tion(s). 48.2.109. Vectors D ialo g Box The Vectors dialo g box controls the displa y of v ector plots . See Displa ying Vectors (p.2794 ) for details about the it ems b elow. Results → Graphics → Vectors → New... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3954Ribbon R eference GuideControls Vector N ame is the name f or a v ector plot definition. You c an sp ecify a name or use the default name vector- id. This c ontrol app ears only f or v ector plot definitions . Options contains check butt ons tha t set v arious displa y options . Global R ange toggles b etween basing the minimum and maximum v alues on the r ange of v alues on the selec ted surfaces (off ), and basing them on the r ange of v alues in the en tire domain (on, the default). Auto Range toggles b etween aut oma tic and manual setting of the r ange of sc alar field v alues . Clip t o Range controls the displa y of v ectors tha t ha ve a v alue outside the r ange sp ecified b y Min and Max.When on, no v ectors ar e displa yed outside the r ange .When off , vectors ar e displa yed outside the r ange using the c olors a t the t op and b ottom of the c olor sc ale.This option is applic able only when Auto Range is off . See Specifying the R ange of M agnitudes D ispla yed (p.2798 ) for details . Auto Sc ale enables the sc aling of all v ectors in the domain such tha t when the Scale is 1, ther e will b e minimal overlap of v ectors. Draw M esh toggles b etween displa ying and not displa ying the mesh. The Mesh D ispla y Dialog Box (p.3239 ) is opened when Draw M esh is selec ted. Style selec ts the st yle in which the v ectors ar e dr awn. Available st yles ar e 3d ar row,3d ar rowhead ,cone , filled-ar row,arrow,harpoon, and headless . Scale sets the fac tor b y which the v ectors should b e sc aled . See Scaling the Vectors (p.2796 ) for details . Skip allows you t o “thin ” or “sample ” the v ectors tha t are displa yed. See Skipping Vectors (p.2797 ) for details . Vector Options ... opens the Vector Options D ialog Box (p.3664 ), in which y ou c an set additional options f or v ector displa ys. (This butt on is not a vailable f or v ector plot definitions .) Custom Vectors... opens the Custom Vectors D ialog Box (p.3664 ), in which y ou c an define y our o wn v ector fields . Color map Options ... opens the Color map D ialog Box (p.3697 ), allo wing y ou t o cust omiz e the c olor map f or this gr aphics objec t. Vectors of contains a list fr om which y ou c an selec t the v ector field t o be plott ed. Color b y contains a list fr om which y ou c an selec t the sc alar field b y which the v ectors ar e color ed. 3955Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonMin shows the v alue t o which the lo wer end of the c olor sc ale is mapp ed.You c an set this v alue manually if Auto Range is off . Max shows the v alue t o which the upp er end of the c olor sc ale is mapp ed.You c an set this v alue manually if Auto Range is off . Surfaces contains a list fr om which y ou c an selec t the sur faces on which t o displa y vectors. In 2D , vectors ar e dis- played on the en tire domain if no sur face is selec ted. New S urface is a dr op-do wn list butt on tha t contains a list of sur face options: Point opens the Point Sur face Dialog Box (p.3898 ). Line/R ake opens the Line/R ake Sur face Dialog Box (p.3847 ). Plane opens the Plane Sur face Dialog Box (p.3895 ). Quadr ic opens the Quadr ic Sur face Dialog Box (p.3899 ). Iso-S urface opens the Iso-Sur face Dialog Box (p.3842 ). Iso-C lip opens the Iso-C lip D ialog Box (p.3841 ). Structural P oint opens the Structural Point Sur face Dialog Box (p.3928 ). Displa y draws the v ectors in the ac tive gr aphics windo w. Comput e calcula tes the sc alar field and up dates the Min and Max values (e ven when Auto Range is off ). Save/D ispla y plots the v ectors in the ac tive gr aphics windo w and sa ves the v ector plot definition. This butt on app ears only f or v ector plot definitions and r eplac es the Displa y butt on. 48.2.110. Volume A daption D ialo g Box The Volume A daption dialo g box allo ws you t o mar k or r efine c ells based on c ell v olume or change in cell v olume .This dialo g box is only a vailable if y ou ha ve used the f ollowing t ext command: mesh/adapt/revert-to-R19.2-user-interface ; not e tha t if y ou r evert the user in terface, you c annot undo it in the cur rent session, and some func tionalit y is no longer a vailable . Domain → Adapt → Mark/A dapt C ells → Volume ... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3956Ribbon R eference GuideControls Options allows you t o sp ecify tha t the mar king and/or r efining is based on v olume magnitude or v olume change . Magnitude enables the mar king/r efining of c ells based on v olume magnitude . Change enables the mar king/r efining of c ells based on the change in v olume . Min displa ys the minimum v alue of c ell v olume or c ell v olume change in the mesh. This v alue is not editable . Max displa ys the maximum v alue of c ell v olume or c ell v olume change in the mesh. This v alue is not editable . Max Volume defines the thr eshold v alue f or mar king/r efining the mesh based on v olume magnitude . Cells tha t ha ve volumes gr eater than the thr eshold ar e mar ked f or refinemen t. Max Volume C hange defines the thr eshold v alue f or mar king/r efining the mesh based on the change in v olume . Cells with volume changes tha t are gr eater than the thr eshold v alue ar e mar ked f or refinemen t. Manage ... opens the Manage A daption R egist ers D ialog Box (p.3848 ), which allo ws you t o displa y and manipula te adaption r egist ers tha t are gener ated using the Mark command . Controls... opens the Mesh A daption C ontrols D ialog Box (p.3851 ), which allo ws you t o control certain asp ects of the adaption pr ocess. Adapt refines the mesh based on either the maximum v olume or the v olume change , and the adaption limits . Mark mar ks cells t o be refined based on either the maximum v olume or the v olume change .This c ommand produces an adaption r egist er. 3957Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonComput e calcula tes the minimum and maximum c ell v olume or c ell v olume change and displa ys them in the Min and Max real numb er fields . 48.2.111. Volume Rep ort Definition D ialo g Box Solution → Rep orts → Definitions → New → Volume Rep ort Controls Options Per Z one specifies whether or not the chosen field v ariable is c alcula ted fr om all of the selec ted c ell z ones combined (default) or individually on each of the selec ted c ell z ones . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3958Ribbon R eference GuideAverage O ver (optional) To ha ve Fluen t calcula te a r unning a verage f or the Volume Rep ort Definition you c an enter a p ositiv e integer gr eater than 1 (the default) f or Average O ver. Specifying a numb er gr eater than 1 means that F luent will pr int, plot , and wr ite the r unning a verage value of the selec ted v ariable inst ead of the curr ent v alue of the same v ariable . The v alue r eported is a veraged o ver the last iterations/time st eps, wher e is y our sp ecified Av- erage O ver value .When the it eration/time st ep numb er is lo wer than , Fluent c alculat es the a v- erage of the a vailable v ariable v alues . Rep ort Files lists all of the r eport files wher e you c an wr ite the r eport definition da ta. Rep ort Plots lists all of the r eport plots wher e you c an plot the r eport definition da ta (assuming this r eport has the same units as the other r eport definitions included in the selec ted r eport plot). Create Rep ort File creates a new r eport file tha t includes this r eport definition. Rep ort Plot creates a new r eport plot tha t includes this r eport definition. Frequenc y specifies ho w fr equen tly the r eport definition is wr itten, plott ed, or pr inted t o the c onsole . Print to Console prints the v alue of the r eport definition t o the c onsole . Create Output P aramet er creates an output par amet er for this r eport definition with the name - op. Rep ort Type selec ts the in tegration metho d used on the selec ted c ell z ones .The a vailable r eport types ar e the same as those in the Volume In tegrals D ialog Box (p.3730 ). See Volume In tegration (p.2949 ) for details . Field Variable contains a list of solution v ariables tha t can b e monit ored on the selec ted c ell z ones .This list will not b e available if y ou selec t Volume as the Rep ort Type. Phase contains a list of all of the phases in the pr oblem tha t you ha ve defined .This is a vailable when the VOF, mixture, or E uler ian multiphase mo del is enabled . Cell Z ones contains a selec table list of the cur rent cell z ones . OK creates the r eport definition. 3959Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonComput e comput es the v alue of the r eport definition a t the selec ted z one(s) and pr ints to the c onsole . 48.2.112. Warning D ialo g Box The Warning dialo g box allo ws you t o sp ecify whether e xisting d ynamic z ones and/or mesh in terfaces are delet ed when y ou ar e using the Merge Z ones dialo g box to mer ge multiple z ones of the same type in to a single z one (see Merge Z ones D ialog Box (p.3850 ) for details). Note tha t dynamic z ones and mesh in terfaces tha t exist a t the time of the mer ge ma y be ad versely aff ected b y the mer ge. The Warning dialo g box op ens aut oma tically when y ou click Merge in the Merge Z ones D ialog Box (p.3850 ) if y our c ase has d ynamic z ones or mesh in terfaces. Controls Canc el M erging retur ns y ou t o the Mesh Z ones dialo g box when y ou click OK, without initia ting the mer ge. Proceed a t Your O wn R isk allows the mer ge t o pr oceed when y ou click OK, without deleting the e xisting d ynamic z ones and mesh interfaces b eforehand . Proceed A fter M esh M anipula tion delet es the e xisting d ynamic z ones and/or mesh in terfaces (based on the settings in the Mesh M anipu- lation group b ox) and then mer ges the z ones when y ou click OK. Mesh M anipula tion allows you t o sp ecify whether the e xisting d ynamic z ones and/or mesh in terfaces ar e delet ed pr ior t o the initia tion of the mer ge.This gr oup b ox is only a vailable when Proceed A fter M esh M anipula tion is se- lected. Dynamic Z ones specifies whether all e xisting d ynamic z ones ar e delet ed pr ior t o the mer ge. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3960Ribbon R eference GuideMesh In terfaces specifies whether all e xisting mesh in terfaces ar e delet ed pr ior t o the mer ge. Note tha t selec ting keep all from b oth dr op-do wn lists in the Mesh M anipula tion group b ox is the equiv alen t of selec ting Proceed a t Your O wn R isk. 48.2.113. Yplus/Ystar A daption D ialo g Box The Yplus/Ystar A daption dialo g box allo ws you t o mar k or adapt b oundar y cells on sp ecified w all zones based on the non-dimensional or par amet er.This dialo g box is only a vailable if y ou ha ve used the f ollowing t ext command:mesh/adapt/revert-to-R19.2-user-interface ; not e that if y ou r evert the user in terface, you c annot undo it in the cur rent session, and some func tionalit y is no longer a vailable . Domain → Adapt → Mark/A dapt C ells → Yplus/Ystar ... Controls Options contains the check butt ons tha t toggle the abilit y to mar k and/or adapt c ells f or refinemen t or c oarsening . Refine toggles the abilit y to refine c ells or mar k cells f or refinemen t. Coarsen toggles the abilit y to coarsen c ells or mar k cells f or coarsening . Type contains the check butt ons tha t enable adaption based on or . Yplus enables adaption. 3961Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonYstar enables adaption. Wall Z ones contains a selec table list of ac tive wall z ones . Boundar y cells asso ciated with the w all z ones y ou selec t will b e mar ked or adapt ed based on the options , thresholds , and limita tions applied in the dialo g box. Min/M ax displa ys the minimum and maximum c ell v alues of or for all c ells asso ciated with visc ous w all z ones . Note tha t these v alues ar e indep enden t of the w all z ones selec ted.The r eal numb er field v alues ar e not editable; the y are pur ely inf ormational. Min A llowed designa tes the thr eshold v alue f or coarsening the mesh. Cells with or values b elow the minimum threshold will b e mar ked f or coarsening . Max A llowed designa tes the thr eshold v alue f or refining the mesh. Cells with or values ab ove the maximum threshold will b e mar ked f or refinemen t. Manage ... opens the Manage A daption R egist ers D ialog Box (p.3848 ), which allo ws you t o displa y and manipula te adaption r egist ers tha t are gener ated using the Mark command . Controls... opens the Mesh A daption C ontrols D ialog Box (p.3851 ), which allo ws you t o control certain asp ects of the adaption pr ocess. Adapt adapts the mesh based the c oarsening and r efining t oggle butt ons, the w all z ones selec ted, the minimum and maximum or allo wed, and the adaption limits . Mark mar ks cells t o be refined and/or c oarsened based on the w all z ones selec ted and the minimum and maximum or allo wed in the mesh. This c ommand pr oduces an adaption r egist er. Comput e comput es the minimum and maximum v alues of or on all c ells on visc ous w alls and displa ys them in the Min and Max real numb er fields . Note tha t these ar e the e xtremes f or the or values of e very cell on a visc ous w all, not just the c ells asso ciated with the selec ted z ones . 48.2.114. Zone S urface Dialo g Box The Zone S urface dialo g box allo ws you t o in teractively cr eate sur faces fr om fac e and c ell z ones in the domain. See Zone Sur faces (p.2729 ) for details ab out the it ems b elow. Domain → Surface → Create → Zone ... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3962Ribbon R eference GuideControls Zone lists z ones tha t you c an selec t for cr eating z one sur faces. Surfaces displa ys an inf ormational list of e xisting sur faces. New S urface Name designa tes the name of the sur face to be created.The default is the z one name . Create creates the sur face. Manage ... opens the Surfaces D ialog Box (p.3933 ) in which y ou c an r ename and delet e sur faces and det ermine their sizes. 3963Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Dialog Boxes A vailable fr om the R ibbonRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3964Appendix A. ANSY S Fluen t Model C ompa tibilit y The f ollowing tables summar ize the c ompa tibilit y of se veral ANSY S Fluen t mo del c ategor ies: •Multiphase M odels (see Modeling M ultiphase F lows (p.2091 )) •Moving D omain M odels (S ee Modeling F lows with M oving R eference Frames (p.1227 )) •Turbulenc e Models (S ee Modeling Turbulenc e (p.1375 )) •Combustion M odels (S ee C hapt ers Modeling S pecies Transp ort and F inite-Rate Chemistr y (p.1613 ) – Modeling Engine Ignition (p.1807 )) Note tha t a ✓ indic ates tha t two mo dels ar e compa tible with each other , while the absenc e of a ✓ in- dicates tha t two mo dels ar e not c ompa tible with each other . Table 1: Moving D omain M odels v s. Multiphase M odels Discrete Phase Mixture VOF Euler ian ✓ ✓ ✓ ✓ Sliding M esh ✓ ✓ ✓ Mixing P lane ✓ ✓ ✓ ✓ Dynamic M esh ✓ ✓ ✓ ✓ Multiple Reference Frame ✓ ✓ ✓ ✓ Single R eference Frame Table 2: Multiphase M odels v s.Turbulenc e M odels LES Reynolds S tress k-omega** k-epsilon* Spalar t−Allmar as ✓ ✓ ✓ Euler ian ✓ ✓ ✓ ✓ ✓ VOF ✓ ✓ ✓ ✓ ✓ Mixture ✓ ✓ ✓ ✓ ✓ Discrete Phase Table 3: Combustion M odels v s. Multiphase M odels Discrete Phase Mixture VOF Euler ian ✓ ✓ ✓ ✓ Laminar F inite Rate ✓ ✓ ✓ ✓ Eddy Dissipa tion ✓ Eddy Dissipa tion Concept 3965Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.✓ Non-P remix ed ✓ Premix ed ✓ Partially P remix ed Euler ian PDF only Comp osition PDF Transp ort ✓ Pollutan ts Table 4: Moving D omain M odels v s.Turbulenc e M odels LES Reynolds S tress k-omega** k-epsilon* Spalar t−Allmar as ✓ ✓ ✓ ✓ ✓ Sliding M esh ✓ ✓ ✓ ✓ Mixing P lane ✓ ✓ ✓ ✓ ✓ Dynamic M esh ✓ ✓ ✓ ✓ ✓ Multiple Reference Frame ✓ ✓ ✓ ✓ ✓ Single Reference Frame Table 5: Combustion M odels v s. Moving D omain M odels Single R eference FrameMultiple R eference FrameDynamic M esh Mixing PlaneSliding Mesh ✓ ✓ ✓ ✓ Laminar F inite Rate ✓ ✓ ✓ ✓ Eddy Dissipa tion ✓ ✓ ✓ ✓ Eddy Dissipa tion Concept ✓ ✓ ✓ ✓ Non-P remix ed ✓ ✓ ✓ ✓ Premix ed ✓ ✓ ✓ ✓ Partially P remix ed ✓ ✓ ✓ ✓ Comp osition PDF Transp ort ✓ ✓ ✓ ✓ Pollutan ts Table 6: Combustion M odels v s.Turbulenc e M odels LES Reynolds Stressk-omega** k-epsilon* Spalar t-Allmar as ✓ ✓ ✓ ✓ ✓ Laminar F inite Rate ✓ ✓ ✓ ✓ Eddy Dissipa tion Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3966ANSY S Fluen t Model C ompa tibilit y✓ ✓ ✓ ✓ Eddy Dissipa tion Concept ✓ ✓ ✓ ✓ Non-P remix ed ✓ ✓ ✓ ✓ Premix ed ✓ ✓ ✓ ✓ Partially Premix ed ✓ ✓ ✓ ✓ Comp osition PDF Transp ort ✓ ✓ ✓ ✓ Pollutan ts Key: ✓ - compa tible * - Includes S tandar d, RNG, and R ealizable k-epsilon mo dels ** - Includes S tandar d, BSL, and SST k-omega mo dels 3967Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3968Appendix B . ANSY S Fluen t File F ormats This app endix pr ovides inf ormation ab out the f ollowing: B.1. Case and D ata File F ormats B.2. Mesh M orpher/Optimiz er File F ormats B.3. Shell C onduc tion S ettings F ile F ormat B.4. 3D F an C urve File F ormat B.1. Case and D ata F ile F ormats This sec tion descr ibes the c ontents and f ormats of ANSY S Fluen t case and da ta files . After discussing the Guidelines (p.3969 ) and Formatting C onventions in B inar y and F ormatted F iles (p.3969 ), the sec tion descr iptions ar e gr oup ed acc ording t o func tion: •Grid Sections (p.3970 ) : Creating gr ids f or ANSY S Fluen t. •Other (N on-G rid) C ase S ections (p.3981 ) •Data Sections (p.3984 ) : Imp orting solutions in to another p ostpr ocessor . The c ase and da ta files ma y contain other sec tions tha t are in tended f or in ternal use only . B.1.1. Guidelines The ANSY S Fluen t case and da ta files ar e br oken in to se veral sec tions acc ording t o the f ollowing guidelines: •Each sec tion is enclosed in par entheses and b egins with a decimal in teger indic ating its t ype.This in teger is diff erent for formatted and binar y files ( Formatting C onventions in B inar y and F ormatted F iles (p.3969 )). •All gr oups of it ems ar e enclosed in par entheses .This mak es sk ipping t o ends of (sub)sec tions and parsing them v ery easy . It also allo ws for easy and c ompa tible addition of new it ems in futur e releases . •Header inf ormation f or lists of it ems is enclosed in separ ate sets of par entheses pr eceding the it ems , and the it ems ar e enclosed in their o wn par entheses . B.1.2. Formatting C onventions in Binar y and F ormatted F iles For formatted files , examples of file sec tions ar e giv en in Grid S ections (p.3970 ) and Other (N on-G rid) Case S ections (p.3981 ). For binar y files , the header indic es descr ibed in this sec tion (f or e xample ,10 for the no de sec tion) ar e pr eceded b y 20 for single-pr ecision binar y da ta, or b y 30 for double-pr ecision binar y da ta (f or e xample ,2010 or 3010 inst ead of 10).The end of the binar y da ta is indic ated b y End of Binary Section 2010 or End of Binary Section 3010 before the closing par- enthesis of the sec tion. An example with the binar y da ta represen ted b y periods is as f ollows: 3969Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. (2010 (2 1 2aad 2 3)( . . . ) End of Binary Section 2010) B.1.3. Grid S ections Grid sec tions ar e stored in the c ase file . A gr id file is a subset of a c ase file , containing only those sec tions pertaining t o the gr id.The cur rently defined gr id sec tions ar e: •Commen t (See Commen t (p.3970 )) •Header (S ee Header (p.3971 )) •Dimensions (S ee Dimensions (p.3971 )) •Nodes (S ee Nodes (p.3971 )) •Periodic S hado w Faces (S ee Periodic S hado w Faces (p.3972 )) •Cells (S ee Cells (p.3973 )) •Faces (S ee Faces (p.3974 )) •Face Tree (S ee Face Tree (p.3976 )) •Cell Tree (S ee Cell Tree (p.3977 )) •Interface Face Parents (S ee Interface Face Parents (p.3977 )) The sec tion ID numb ers ar e indic ated in b oth symb olic and numer ic forms.The symb olic r epresen tations are available as symb ols in a Scheme sour ce file (xfile.scm ), which is a vailable fr om ANSY S Inc ., or as macr os in a C header file ( xfile.h ), which is lo cated in y our installa tion ar ea. B.1.3.1. Comment 0 Inde x: xf-comment Scheme symb ol: XF_COMMENT C macr o: optional Status: Commen t sec tions c an app ear an ywher e in the file (e xcept within other sec tions) as: (0 "comment text") You should pr ecede each long sec tion, or gr oup of r elated sec tions , by a c ommen t sec tion e xplaining wha t is t o follow. Example: (0 "Variables:") (37 ( (relax-mass-flow 1) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3970ANSY S Fluen t File F ormats (default-coefficient ()) (default-method 0) )) B.1.3.2. Header 1 Inde x: xf-header Scheme symb ol: XF_HEADER C macr o: optional Status: Header sec tions c an app ear an ywher e in the file (e xcept within other sec tions). The f ollowing is an example: (0 "fluent19.5.0 build-id: 0") The pur pose of this sec tion is t o iden tify the pr ogram tha t wr ote the file . Although it c an app ear anywher e, it is one of the first sec tions in the file . Additional header sec tions indic ate other pr ograms that ma y ha ve been used in gener ating the file . It provides a hist ory mechanism sho wing wher e the file c ame fr om and ho w it w as pr ocessed . B.1.3.3. Dimensions 2 Inde x: xf-dimension Scheme symb ol: XF_DIMENSION C macr o: optional Status: The dimensions of the gr id app ear as: (2 ND) wher e ND is 2 or 3. This sec tion is supp orted as a check tha t the gr id has the appr opriate dimension. B.1.3.4. Nodes 10 Inde x: xf-node Scheme symb ol: XF_NODE C macr o: requir ed Status: Format: (10 (zone-id first-index last-index type ND)( x1 y1 z1 x2 y2 z2 . . . )) 3971Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Case and D ata File F ormats•If zone-id is zero, this pr ovides the t otal numb er of no des in the gr id.first-index will then b e one , last-index will b e the t otal numb er of no des in he xadecimal ,type is equal t o 1,ND is the dimension- ality of the gr id, and ther e are no c oordina tes following (the par entheses f or the c oordina tes ar e omitt ed as w ell). For e xample:(10 (0 1 2d5 1 2)) •If zone-id is gr eater than z ero, it indic ates the z one t o which the no des b elong .first-index and last-index are the indic es of the no des in the z one ,in he xadecimal .The v alues of last-index in each z one must b e less than or equal t o the v alue in the declar ation sec tion. Type is alw ays equal t o 1. ND is an optional ar gumen t tha t indic ates the dimensionalit y of the no de da ta, wher e ND is 2 or 3. If the numb er of dimensions in the gr id is t wo, as sp ecified b y the no de header , then only and coordina tes ar e pr esen t on each line . The f ollowing is an e xample of a 2D gr id: (10 (1 1 2d5 1 2)( 1.500000e-01 2.500000e-02 1.625000e-01 1.250000e-02 . . . 1.750000e-01 0.000000e+00 2.000000e-01 2.500000e-02 1.875000e-01 1.250000e-02 )) Because the gr id connec tivit y is c omp osed of in tegers r epresen ting p ointers (see C ells and F aces), using he xadecimal c onser ves spac e in the file and pr ovides f or fast er file input and output. The header indic es ar e in he xadecimal so tha t the y ma tch the indic es in the b odies of the gr id connec tivit y sections .The zone-id and type are also in he xadecimal f or c onsist ency. B.1.3.5. Perio dic Shado w F aces 18 Inde x: xf-periodic-face Scheme symb ol: XF_PERIODIC_FACE C macr o: requir ed only f or gr ids with p eriodic b oundar ies Status: This sec tion indic ates the pair ings of p eriodic fac es on p eriodic b oundar ies. Grids without p eriodic boundar ies do not ha ve sec tions of this t ype.The f ormat of the sec tion is as f ollows: (18 (first-index last-index periodic-zone shadow-zone)( f00 f01 f10 f11 f20 f21 . . . )) wher e Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3972ANSY S Fluen t File F ormatsfirst-index = inde x of the first p eriodic fac e pair in the list last-index = inde x of the last p eriodic fac e pair in the list periodic-zone = z one ID of the p eriodic fac e zone shadow-zone = z one ID of the c orresponding shado w fac e zone These ar e in he xadecimal f ormat.The indic es in the sec tion b ody (f*) refer to the fac es on each of the p eriodic b oundar ies (in he xadecimal), the indic es b eing off sets in to the list of fac es for the gr id. Note In this c ase,first-index and last-index do not refer to fac e indic es.They refer to indic es in the list of p eriodic pairs . Example: (18 (1 2b a c) ( 12 1f 13 21 ad 1c2 . . . )) B.1.3.6. Cells 12 Inde x: xf-cell Scheme symb ol: XF_CELL C macr o: requir ed Status: The declar ation sec tion f or c ells is similar t o tha t for no des. (12 (zone-id first-index last-index type element-type)) Again,zone-id is z ero to indic ate tha t it is a declar ation of the t otal numb er of c ells. If last-index is zero, then ther e ar e no c ells in the gr id.This is useful when the file c ontains only a sur face mesh to aler t ANSY S Fluen t tha t it c annot b e used . In a declar ation sec tion, the type has a v alue of z ero and the element-type is not pr esen t. For e xample , (12 (0 1 3e3 0)) It sta tes tha t ther e ar e 3e3 (he xadecimal) = 995 c ells in the gr id.This declar ation sec tion is r equir ed and must pr ecede the r egular c ell sec tions . The element-type in a r egular c ell sec tion header indic ates the t ype of c ells in the sec tion, as f ollows: faces/c ell nodes/c ell description element-type mixed 0 3973Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Case and D ata File F ormatsfaces/c ell nodes/c ell description element-type 3 3 triangular 1 4 4 tetrahedr al 2 4 4 quadr ilateral 3 6 8 hexahedr al 4 5 5 pyramid 5 5 6 wedge 6 NF NN polyhedr al 7 wher e NN and NF will v ary, dep ending on the sp ecific p olyhedr al cell. Regular c ell sec tions ha ve no b ody, but the y ha ve a header of the same f ormat wher e first-index and last-index indic ate the r ange f or the par ticular z one ,type indic ates whether the c ell z one is an ac tive zone (solid or fluid), or inac tive zone (cur rently only par ent cells r esulting fr om hanging node adaption). Active zones ar e represen ted with type =1, while inac tive zones ar e represen ted with type =32. In the ear lier v ersions of ANSY S Fluen t, a distinc tion w as made b etween solid and fluid z ones .This is now det ermined b y pr operties (tha t is, ma terial t ype). A type of z ero indic ates a dead z one and will b e sk ipped b y ANSY S Fluen t. If a z one is of mix ed t ype (element-type =0), it will ha ve a b ody tha t lists the element-type of each c ell. Example : (12 (9 1 3d 0 0)( 1 1 1 3 3 1 1 3 1 . . . )) Here, ther e ar e 3D (he xadecimal) = 61 c ells in c ell z one 9, of which the first 3 ar e triangles , the ne xt 2 ar e quadr ilaterals, and so on. B.1.3.7. Faces 13 Inde x: xf-face Scheme symb ol: XF_FACE C macr o: requir ed Status: The f ormat for fac e sec tions is as f ollows: (13 (zone-id first-index last-index bc-type face-type)) wher e zone-id = z one ID of the fac e sec tion first-index = inde x of the first fac e in the list Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3974ANSY S Fluen t File F ormatslast-index = inde x of the last fac e in the list bc-type = ID of the b oundar y condition r epresen ted b y the fac e sec tion face-type = ID of the t ype(s) of fac e(s) in the sec tion The cur rent valid b oundar y condition t ypes ar e defined in the f ollowing table: descr iption bc-type interior 2 wall 3 pressur e-inlet , inlet-v ent, intake-fan 4 pressur e-outlet , exhaust-fan, outlet-v ent 5 symmetr y 7 periodic-shado w 8 pressur e-far-field 9 velocity-inlet 10 periodic 12 fan, porous-jump , radia tor 14 mass-flo w-inlet , mass-flo w-outlet 20 interface 24 parent (hanging no de) 31 outflo w 36 axis 37 The fac es resulting fr om the in tersec tion of non-c onformal gr ids ar e plac ed in a separ ate fac e zone , wher e a fac tor of 1000 is added t o the bc-type (for e xample , 1003 is a w all z one). The cur rent valid fac e types ar e defined in the f ollowing table: nodes/fac e descr iption face-type mixed 0 2 linear 2 3 triangular 3 4 quadr ilateral 4 NN polygonal 5 wher e NN will v ary, dep ending on the sp ecific p olygonal fac e. A zone-id of z ero indic ates a declar ation sec tion, which pr ovides a c oun t of the t otal numb er of faces in the file . Such a sec tion omits the bc-type and is not f ollowed b y a b ody with fur ther inf orm- ation. A nonz ero zone-id indic ates a r egular fac e sec tion, and will b e followed b y a b ody tha t contains information ab out the gr id connec tivit y. Each line of the b ody will descr ibe one fac e and will ha ve the f ollowing f ormat: n0 n1 n2 c0 c1 3975Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Case and D ata File F ormatswher e, n* = defining no des (v ertices) of the fac e c* = adjac ent cells This is the f ormat for a 3D gr id with a tr iangular fac e format.The ac tual numb er of no des dep ends on the face-type .The or der of the c ell indic es is imp ortant, and is det ermined b y the r ight-hand rule: if y ou cur l the fingers of y our r ight hand in the or der of the no des, your thumb will p oint toward c0. For 2D gr ids,n2 is omitt ed.c1 is det ermined b y the cr oss pr oduc t of t wo vectors, and .The vector e xtends fr om n0 to n1, wher eas the vector has its or igin a t n0 and p oints out of the gr id plane t oward the view er. If you e xtend y our r ight hand along and cur l your fingers in the dir ection of the angle b etween and , your thumb will p oint along toward c1. If the fac e zone is of mix ed t ype (face-type = 0) or of p olygonal t ype (face-type = 5), each line of the sec tion b ody will b egin with a r eference to the numb er of no des tha t mak e up tha t par ticular face, and has the f ollowing f ormat: x n0 n1 ... nf c0 c1 wher e, x = the numb er of no des (v ertices) of the fac e nf = the final no de of the fac e All cells, faces, and no des ha ve positiv e indic es. If a fac e has a c ell only on one side , then either c0 or c1 is z ero. For files c ontaining only a sur face mesh, both these v alues ar e zero. For inf ormation on fac e-no de c onnec tivit y for v arious c ell t ypes in ANSY S Fluen t, refer to Face-Node Connec tivit y in ANSY S Fluen t (p.709). B.1.3.8. Face Tree 59 Inde x: xf-face-tree Scheme symb ol: XF_FACE_TREE C macr o: only f or gr ids with hanging no de adaption Status: This sec tion indic ates the fac e hier archy of the gr id containing hanging no des.The f ormat of the section is as f ollows: (59 (face-id0 face-id1 parent-zone-id child-zone-id) ( number-of-kids kid-id-0 kid-id-1 ... kid-id-n . . . )) wher e, Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3976ANSY S Fluen t File F ormatsface-id0 = inde x of the first par ent fac e in the sec tion face-id1 = inde x of the last par ent fac e in the sec tion parent-zone-id = ID of the z one c ontaining par ent fac es child-zone-id = ID of the z one c ontaining childr en fac es number-of-kids = the numb er of childr en of the par ent fac e kid-id-n = the fac e IDs of the childr en These ar e in he xadecimal f ormat. B.1.3.9. Cell Tree 58 Inde x: xf-cell-tree Scheme symb ol: XF_CELL_TREE C macr o: only f or gr ids with hanging no de adaption Status: This sec tion indic ates the c ell hier archy of the gr id containing hanging no des.The f ormat of the section is as f ollows: (58 (cell-id0 cell-id1 parent-zone-id child-zone-id) ( number-of-kids kid-id-0 kid-id-1 ... kid-id-n . . . )) wher e, cell-id0 = inde x of the first par ent cell in the sec tion cell-id1 = inde x of the last par ent cell in the sec tion parent-zone-id = ID of the z one c ontaining par ent cells child-zone-id = ID of the z one c ontaining childr en c ells number-of-kids = the numb er of childr en of the par ent cell kid-id-n = the c ell IDs of the childr en These ar e in he xadecimal f ormat. B.1.3.10. Interface Face Parents 61 Inde x: xf-face-parents Scheme symb ol: XF_FACE_PARENTS C macr o: only f or gr ids with non-c onformal in terfaces Status: This sec tion indic ates the r elationship b etween the in tersec tion fac es and or iginal fac es.The in tersec tion faces (childr en) ar e pr oduced fr om in tersec ting t wo non-c onformal sur faces (par ents) and ar e some 3977Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Case and D ata File F ormatsfraction of the or iginal fac e. Each child will r efer to at least one par ent.The f ormat of the sec tion is as follows: (61 (face-id0 face-id1) ( parent-id-0 parent-id-1 . . . )) wher e, face-id0 = inde x of the first child fac e in the section face-id1 = inde x of the last child fac e in the section parent-id-* = inde x of par ent fac es These ar e in he xadecimal f ormat. If you set up and sa ve a non-c onformal mesh in the solution mo de of F luen t and then r ead it using the meshing mo de of F luen t, this sec tion will b e sk ipped; consequen tly, all the inf ormation nec essar y to pr eser ve the non-c onformal in terface will not b e main tained .When y ou swit ch t o or r ead the mesh back in to the solution mo de, you will need t o recreate the in terface. B.1.3.11. Example F iles B.1.3.11.1. Example 1 Figur e 1: Quadr ilateral M esh (p.3978 ) illustr ates a simple quadr ilateral mesh with no p eriodic b ound- aries or hanging no des. Figur e 1: Quadr ilateral M esh The f ollowing descr ibes this mesh: (0 "Grid:") (0 "Dimensions:") (2 2) (12 (0 1 3 0)) (13 (0 1 a 0)) (10 (0 1 8 0 2)) (12 (7 1 3 1 3)) (13 (2 1 2 2 2)( 1 2 1 2 3 4 2 3)) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3978ANSY S Fluen t File F ormats (13 (3 3 5 3 2)( 5 1 1 0 1 3 2 0 3 6 3 0)) (13 (4 6 8 3 2)( 7 4 3 0 4 2 2 0 2 8 1 0)) (13 (5 9 9 a 2)( 8 5 1 0)) (13 (6 a a 24 2)( 6 7 3 0)) (10 (1 1 8 1 2) ( 1.00000000e+00 0.00000000e+00 1.00000000e+00 1.00000000e+00 2.00000000e+00 0.00000000e+00 2.00000000e+00 1.00000000e+00 0.00000000e+00 0.00000000e+00 3.00000000e+00 0.00000000e+00 3.00000000e+00 1.00000000e+00 0.00000000e+00 1.00000000e+00)) B.1.3.11.2. Example 2 Figur e 2: Quadr ilateral M esh with P eriodic B oundar ies (p.3979 ) illustr ates a simple quadr ilateral mesh with p eriodic b oundar ies but no hanging no des. In this e xample , bf9 and bf10 ar e fac es on the periodic z ones . Figur e 2: Quadr ilateral M esh with P eriodic B oundar ies The f ollowing descr ibes this mesh: (0 "Dimensions:") (2 2) (0 "Grid:") (12 (0 1 3 0)) (13 (0 1 a 0)) (10 (0 1 8 0 2)) (12 (7 1 3 1 3)) (13 (2 1 2 2 2)( 1 2 1 2 3 4 2 3)) (13 (3 3 5 3 2)( 5 1 1 0 1 3 2 0 3 6 3 0)) (13 (4 6 8 3 2)( 7 4 3 0 4 2 2 0 2 8 1 0)) 3979Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Case and D ata File F ormats (13 (5 9 9 c 2)( 8 5 1 0)) (13 (1 a a 8 2)( 6 7 3 0)) (18 (1 1 5 1)( 9 a)) (10 (1 1 8 1 2)( 1.00000000e+00 0.00000000e+00 1.00000000e+00 1.00000000e+00 2.00000000e+00 0.00000000e+00 2.00000000e+00 1.00000000e+00 0.00000000e+00 0.00000000e+00 3.00000000e+00 0.00000000e+00 3.00000000e+00 1.00000000e+00 0.00000000e+00 1.00000000e+00)) B.1.3.11.3. Example 3 Figur e 3: Quadr ilateral M esh with Hanging N odes (p.3980 ) illustr ates a simple quadr ilateral mesh with hanging no des. Figur e 3: Quadr ilateral M esh with H anging N odes The f ollowing descr ibes this mesh: (0 "Grid:") (0 "Dimensions:") (2 2) (12 (0 1 7 0)) (13 (0 1 16 0)) (10 (0 1 d 0 2)) (12 (7 1 6 1 3)) (12 (1 7 7 20 3)) (58 (7 7 1 7)( 4 6 5 4 3)) (13 (2 1 7 2 2)( 1 2 6 3 1 3 3 4 1 4 4 5 1 5 5 6 6 7 1 2 5 8 2 6 9 5 2 5)) (13 (3 8 b 3 2)( a 6 1 0 6 9 2 0 4 b 4 0 9 4 5 0)) (13 (4 c f 3 2)( Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3980ANSY S Fluen t File F ormats 2 8 6 0 c 2 3 0 8 7 2 0 7 d 1 0)) (13 (5 10 10 a 2)( d a 1 0)) (13 (6 11 12 24 2)( 3 c 3 0 b 3 4 0)) (13 (b 13 13 1f 2)( c 8 7 0)) (13 (a 14 14 1f 2)( b c 7 0)) (13 (9 15 15 1f 2)( 9 b 7 0)) (13 (8 16 16 1f 2)( 9 8 2 7)) (59 (13 13 b 4)( 2 d c)) (59 (14 14 a 6)( 2 12 11)) (59 (15 15 9 3)( 2 b a)) (59 (16 16 8 2)( 2 7 6)) (10 (1 1 d 1 2) ( 2.50000000e+00 5.00000000e-01 2.50000000e+00 1.00000000e+00 3.00000000e+00 5.00000000e-01 2.50000000e+00 0.00000000e+00 2.00000000e+00 5.00000000e-01 1.00000000e+00 0.00000000e+00 1.00000000e+00 1.00000000e+00 2.00000000e+00 1.00000000e+00 2.00000000e+00 0.00000000e+00 0.00000000e+00 0.00000000e+00 3.00000000e+00 0.00000000e+00 3.00000000e+00 1.00000000e+00 0.00000000e+00 1.00000000e+00)) B.1.4. Other (N on-G rid) C ase S ections The f ollowing sec tions st ore boundar y conditions , ma terial pr operties, and solv er control settings . B.1.4.1. Zone B.1.4.2. Partitions B.1.4.1. Zone 39 or 45 Inde x: xf-rp-tv Scheme symb ol: XF_RP_TV C macr o: 3981Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Case and D ata File F ormatsrequir ed Status: There is t ypic ally one z one sec tion f or each z one r eferenced b y the gr id. Although some gr id zones may not ha ve corresponding z one sec tions , ther e cannot b e mor e than one z one sec tion f or each zone . A zone sec tion has the f ollowing f orm: (39 (zone-id zone-type zone-name domain-id)( (condition1 . value1) (condition2 . value2) (condition3 . value3) . . . )) Grid gener ators and other pr eprocessors need only pr ovide the sec tion header and lea ve the list of conditions empt y, as in (39 (zone-id zone-type zone-name domain-id)()) The empt y par entheses a t the end ar e requir ed.The solv er adds c onditions as appr opriate, dep ending on the z one t ype.When only zone-id ,zone-type ,zone-name , and domain-id are sp ecified , the inde x 45 is pr eferred f or a z one sec tion. However, the inde x 39 must b e used if b oundar y condi- tions ar e pr esen t, because an y and all r emaining inf ormation in a sec tion of inde x 45 after zone- id,zone-type ,zone-name , and domain-id will b e ignor ed. Here the zone-id is in decimal format.This is in c ontrast t o the use of he xadecimal in the gr id sec- tions . The zone-type is one of the f ollowing: axis exhaust fan fan fluid inlet vent intake fan interface interior mass-flow-inlet mass-flow-outlet outlet vent outflow periodic porous-jump pressure-far-field pressure-inlet pressure-outlet radiator shadow solid symmetry velocity-inlet wall The interior ,fan ,porous-jump , and radiator types c an b e assigned only t o zones of fac es inside the domain. The interior type is used f or the fac es within a c ell z one; the others ar e for interior fac es tha t form infinit ely thin sur faces within the domain. ANSY S Fluen t allo ws the wall type to be assigned t o fac e zones b oth on the inside and on the b oundar ies of the domain. Some z one Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3982ANSY S Fluen t File F ormatstypes ar e valid only f or c ertain t ypes of gr id comp onen ts. For e xample , cell (elemen t) zones c an b e assigned only one of the f ollowing t ypes: fluid solid All of the other t ypes list ed ab ove can b e used only f or b oundar y (fac e) zones . The zone-name is a user-sp ecified lab el for the z one . It must b e a v alid Scheme symb ol 1 and is written without quot es.The r ules f or a v alid zone-name (Scheme symb ol) ar e as f ollows: •The first char acter must b e a lo wercase lett er 2 or a sp ecial-initial. •Each subsequen t char acter must b e a lo wercase lett er, a sp ecial-initial, a digit , or a sp ecial-subsequen t. wher e a sp ecial-initial char acter is one of the f ollowing: ! $ % & * / : < = > ? ~ _ ^ and a sp ecial-subsequen t is one of the f ollowing: . + - Examples of v alid z one names ar e inlet-port/cold!—, eggs/easy , and e=m*cˆ2 . Some e xamples of z one sec tions pr oduced b y gr id gener ators and pr eprocessors ar e as f ollows: (39 (1 fluid fuel 1)()) (39 (8 pressure-inlet pressure-inlet-8 2)()) (39 (2 wall wing-skin 3)()) (39 (3 symmetry mid-plane 1)()) The domain-id is an in teger tha t app ears af ter the z one name , asso ciating the b oundar y condition with a par ticular phase or mix ture (sometimes r eferred t o as phase-domains and mix ture-domains). B.1.4.2. Partitions 40 Inde x: xf-partition Scheme symb ol: XF_PARTITION C macr o: only f or par titioned gr ids Status: This sec tion indic ates each c ell’s par tition. The f ormat of the sec tion is as f ollows: (40 (zone-id first-index last-index partition-count)( p1 p2 p3 . . . 1See R evised (4) Report on the A lgor ithmic Language Scheme ,William C linger and J ona than R ees (E ditors), 2 N ovemb er 1991, Section 7.1.1. 2The S tandar d ac tually only r equir es tha t case b e insignific ant; the ANSY S Fluen t implemen tation acc omplishes this b y converting all upp ercase input t o lowercase. 3983Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Case and D ata File F ormats pn )) wher e, p1 = the par tition of the c ell whose ID is first-index p2 = the par tition of the c ell whose ID is first-index , and so on pn = the par tition of the c ell whose ID is last-index partition-count = the t otal numb er of par titions Partition IDs must b e between 0 and one less than partition-count . B.1.5. Data S ections The f ollowing sec tions st ore iterations , residuals , and da ta field v alues . B.1.5.1. Grid Size B.1.5.2. Data Field B.1.5.3. Residuals B.1.5.1. Grid S ize 33 Inde x: xf-grid-size Scheme symb ol: XF_GRID_SIZE C macr o: optional Status: This sec tion indic ates the numb er of c ells, faces, and no des in the gr id tha t corresponds t o the da ta in the file .This inf ormation is used t o check tha t the da ta and gr id ma tch.The f ormat is (33 (n-elements n-faces n-nodes)) wher e the in tegers ar e wr itten in decimal. B.1.5.2. Data F ield 300 Inde x: xf-rf-seg-data Scheme symb ol: XF_RF_SEG_DATA C macr o: requir ed Status: This sec tion lists a flo w field solution v ariable f or a c ell or fac e zone .The da ta ar e stored in the same order as the c ells or fac es in the c ase file . Separ ate sec tions ar e wr itten out f or each v ariable f or each face or c ell z one on which the v ariable is st ored.The f ormat is (300 (sub-section-id zone-id size n-time-levels n-phases first-id last-id) ( data for cell or face with id = first-id data-for-cell-or-face with id = first-id+1 .. data-for-cell-or-face with id = last-id )) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3984ANSY S Fluen t File F ormatswher e sub-section-id is a (decimal) in teger tha t iden tifies the v ariable field (f or e xample , 1 for pressur e, 2 for v elocity).The c omplet e list of these is a vailable in the header file ( xfile.h ), which is lo cated in y our installa tion ar ea. wher e, zone-id = the ID numb er of the c ell or fac e zone size = the length of the v ariable v ector zone-id ma tches the ID used in c ase file .size is 1 f or a sc alar, 2 or 3 f or a v ector, equal t o the numb er of sp ecies f or v ariables defined f or each sp ecies).n-time-levels cur rently ar e not used . A sample da ta file sec tion f or the v elocity field in a c ell z one f or a st eady-sta te, single-phase , 2D problem is sho wn b elow: (300 (2 16 2 0 0 17 100) (8.08462024e-01 8.11823010e-02 8.78750622e-01 3.15509699e-02 1.06139672e+00 -3.74040119e-02 ... 1.33301604e+00 -5.04243895e-02 6.21703446e-01 -2.46118382e-02 4.41687912e-01 -1.27046436e-01 1.03528820e-01 -1.01711005e-01 )) The v ariables tha t are list ed in the da ta file dep end on the mo dels ac tive at the time the file is wr itten. Variables tha t are requir ed b y the solv er based on the cur rent mo del settings but ar e missing fr om the da ta file ar e set t o their default v alues when the da ta file is r ead. Any extra variables tha t are presen t in the da ta file but ar e not r elevant acc ording t o cur rent mo del settings ar e ignor ed. B.1.5.3. Residuals 302 Inde x: xf-rf-scaled-residuals Scheme symb ol: XF_RF_SCALED_RESIDUALS C macr o: optional Status: This sec tion lists the v alues of the r esiduals f or a par ticular da ta field v ariable a t each it eration: (302 (n residual-section-id size domain-id) ( iteration_number unscaled_residual scaling_factor . . . )) wher e, n = the numb er of r esiduals size = the length of the v ariable v ector residual-section-id = an in teger (decimal) indic ating the equa tion 3985Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Case and D ata File F ormatsdomain-id = domain ID size is 1 f or a sc alar, 2 or 3 f or a v ector, equal t o the numb er of sp ecies f or v ariables defined f or each sp ecies .The residual-section-id indic ates the equa tion f or which the r esidual is st ored in the sec tion, acc ording t o the C c onstan ts defined in a header file ( xfile.h ) available in y our in- stalla tion ar ea, as not ed in Grid S ections (p.3970 ). The equa tions f or which r esiduals ar e list ed in the da ta file dep end on the mo dels ac tive at the time the file is wr itten. If the r esidual hist ory is missing fr om the da ta file f or a cur rently ac tive equa tion, it is initializ ed with z eros. B.2. Mesh M orpher/Optimiz er F ile F ormats This sec tion descr ibes the f ormat of the ASCII t ext files tha t can b e used as par t of the setup f or the mesh mor pher/optimiz er, as descr ibed in Using the M esh M orpher/Optimiz er (p.3181 ). The f ollowing is an e xample of a file tha t can b e read or wr itten fr om the Define C ontrol P oints D ialog Box (p.3800 ): Control Point Positions CP No. X Y Z 1 0.73398191 -0.048181638 5.0344162 2 0.51003051 0.52833155 5.100265 3 0.10806149 0.72560567 5.1306067 4 -0.37284759 0.62890923 5.1368165 5 -0.69803506 0.21491928 5.144598 The f ollowing is an e xample of a file tha t can b e read or wr itten fr om the Motion S ettings D ialog Box (p.3867 ) when Regular is selec ted fr om the Control P oint Distribution list in the Regions tab of the Mesh M orpher/Optimiz er D ialog Box (p.3854 ): Reg CP Par X Y Z def-0 2 par1 -1 0 0 def-0 4 par1 2 -1 3 def-0 2 par2 0 1 0 def-1 2 par3 0 0 1 def-1 3 par1 2 0 2 The f ollowing is an e xample of a file tha t can b e read or wr itten fr om the Motion S ettings D ialog Box (p.3867 ) when Unstr uctured is selec ted fr om the Control P oint Distribution list in the Regions tab of the Mesh M orpher/Optimiz er D ialog Box (p.3854 ): Motion Definition Name Type Par Dir-x Dir-y Dir-z Orig-x Orig-y Orig-z rad-par1-1 Rad par-1 0 0 1 0 0 0 tra-par2-1 Trans par-2 1 1 1 rot-par3-1 Rot par-3 1 0 0 2 1 1 Assignment to Control Points Name Control Points... rad-par1-1 1 2 3 4 5 6 7 When cr eating or editing a t ext file used t o set up the mesh mor pher/optimiz er, not e the f ollowing: •The file c an b e created fr om nothing using a t ext edit or or spr eadsheet pr ogram, as long as it adher es to the f ormats descr ibed in this sec tion. An easier alt ernative is t o apply some sample definitions using the appr opriate dialo g box, write a file , and then edit the file using a t ext edit or or spr eadsheet pr ogram. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3986ANSY S Fluen t File F ormats•The file must b e a tab-delimit ed ASCII t ext file . •The names of the def ormation r egions (f or e xample ,def-0 ), def ormation par amet ers (f or e xample ,par1 ), and motions (f or e xample ,tra-par2-1 ) must c orrespond t o those tha t exist in the in tended c ase file . •When defining c ontrol p oints, the c oordina tes must lie within a def ormation r egion in the in tended c ase file. •For the motion settings , the c ontrol p oint numb ers must r ange b etween 1 and the maximum numb er of available c ontrol p oints in the in tended c ase file . •The dir ection c omp onen ts and c oordina tes c an b e an y real numb ers. B.3. Shell C onduc tion S ettings F ile F ormat This sec tion descr ibes the f ormat of the CSV files tha t can define shell c onduc tion settings , as descr ibed in Managing S hell C onduc tion Walls (p.1484 ).The f ollowing is an e xample of such a file: Zone ID,Zone Name,Layer Number,Material,Layer Thickness (m),Heat Generation Rate (w/m3) 15,wall-1,1,substrate,5.00E-08,0 15,wall-1,2,substrate,5.00E-08,0 15,wall-1,3,substrate,5.00E-08,0 15,wall-1,4,substrate,5.00E-08,0 15,wall-1,5,gold,2.50E-08,0 15,wall-1,6,gold,2.50E-08,0 16,wall-2,1,silicon,5.00E-08,6.25E+11 16,wall-2,2,silicon,5.00E-08,6.25E+11 16,wall-2,3,substrate,5.00E-08,0 When cr eating or editing a file tha t defines the shell c onduc tion settings , not e the f ollowing: •The file c an b e created fr om nothing using a t ext edit or or spr eadsheet pr ogram, as long as it adher es to the f ormat descr ibed in this sec tion. An easier alt ernative is t o apply some sample shell c onduc tion definitions using the Shell C onduc tion M anager D ialog Box (p.3927 ), gener ate a file using the Write... butt on, and then edit the file using a t ext edit or or spr eadsheet pr ogram. •The file must b e a c omma-delimit ed ASCII file . •The first line c ontains the c olumn headings sho wn in the pr evious e xample , and then each of the subsequen t lines define the settings f or a la yer. •The z one IDs , zone names , layer numb ers, and ma terials (f or e xample ,wall-1 ,substrate ) must c orrespond to those tha t exist in the in tended c ase file . •The la yer thick nesses must b e positiv e, nonz ero values . •Information will not b e wr itten for an y wall tha t defines the hea t gener ation r ate using a UDF . B.4. 3D F an C urve File F ormat This sec tion descr ibes the f ormat of the ASCII t ext files tha t can define the r elationship b etween pr essur e and flo w rate for all of the 3D fan c ell z ones in a c ase file , as descr ibed in 3D F an Z ones (p.899).The following is an e xample of such a file: cell zone id 17 !CELL_ID 3987Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.3D F an C urve File F ormatPressure(Pa) Flowrate(m3/s) -324.0 1.255 -215.0 1.162 -109.0 1.032 0.0 0.997 63.0 0.913 105.0 0.862 302.0 0.584 394.0 0.492 406.0 0.432 443.0 0.365 cell zone id 18 !CELL_ID Pressure(Pa) Flowrate(m3/s) -333.0 1.130 -215.0 1.122 -165.0 1.064 0.0 0.981 42.0 0.912 90.0 0.855 112.0 0.786 303.0 0.546 344.0 0.492 395.0 0.451 411.0 0.399 442.0 0.324 When cr eating or editing a file tha t defines the 3D fan z one cur ve, not e the f ollowing: •The file c an b e created fr om nothing using a t ext edit or or spr eadsheet pr ogram, as long as it adher es to the f ormat descr ibed in this sec tion. •The file must b e a tab-delimit ed ASCII file . •A single file c an define multiple c ell z ones , but it must b e read in each of the applic able Fluid dialo g boxes. •For each sec tion tha t defines the cur ve for a c ell z one , the first thr ee lines must f ollow the c onvention sho wn in the pr evious e xample , and then each of the subsequen t lines must list the e xperimen tal r esults . •The z one IDs (f or e xample ,12) must c orrespond t o those tha t exist in the in tended c ase file . •The units must ma tch those in the c ase file . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3988ANSY S Fluen t File F ormatsAppendix C. Controlling CHEMKIN-CFD S olver P aramet ers U sing Text Commands You ha ve acc ess t o man y par amet er settings tha t can b e used t o control or impr ove the p erformanc e and c onvergenc e behavior of the CHEMKIN-CFD solv er within ANSY S Fluen t.These par amet ers ar e ac- cessed thr ough the ANSY S Fluen t Text User In terface (TUI), through t yped t ext commands .This app endix descr ibes the a vailable par amet ers, their default v alues , and their r ecommended use . In gener al, default settings f or the CHEMKIN-CFD par amet ers should b e sufficien t for most pr oblems . However, it ma y be nec essar y to change these settings t o impr ove performanc e for sp ecific t ypes of problems . In par ticular , the most appr opriate solv er par amet ers ma y vary dep ending on the na ture of the chemistr y set. For e xample , for chemistr ies with man y trace sp ecies tha t ha ve a lar ge impac t on solution r esults (tha t is, the chemistr y is “stiff”), solution t oler ances should b e relatively small (f or e xample , 1.E-9 t o 1.E-12 for absolut e toler ances and 1.E-4 t o 1.E-5 f or relative toler ances). For chemistr y descr iptions wher e all of the sp ecies included ar e within a f ew or ders of magnitude in t erms of mass fr action, however, much looser t oler ances ar e mor e appr opriate. Also, dep ending on the char acteristic time sc ales of the dominan t chemic al reactions , you ma y need t o adjust the maximum time-st ep used b y the CHEMKIN-CFD solv er. /define/models/species/CHEMKIN-CFD-parameters> basic-options Print Level [0] Absolute Tolerance For Gas Species [1e-08] Relative Tolerance For Gas Species [0.0001] Absolute Tolerance For Surface Species [1e-08] Relative Tolerance For Surface Species [0.0001] /define/models/species/CHEMKIN-CFD-parameters> advanced-options Pseudo Time Stepping Solver Option (0:Basic 1:Robust) [1] Pseudo Time Stepping Size [0.0001] Maximum Pseudo Time Step Attempts [1] Maximum Time Step Allowed [0.01] Minimum Time Step Allowed [1e-10] Initial Time Step For Solver [0] Upper Bound For Gas Species Mass Fractions [1.01] Lower Bound For Gas Species Mass Fractions [-1e-12] Upper Bound For Surface Species Mass Fractions [1.1] Lower Bound For Surface Species Mass Fractions [-0.0001] Small Positive Value To Replace Negative Mass Fractions [1e-12] Enter Auxiliary Input Filename [""] Enter Arbitrary String [""] Enter Arbitrary Value [0] Table 1: Summar y of B asic CHEMKIN-CFD P aramet ers (p.3990 ) and Table 2: Summar y of A dvanced CHEMKIN- CFD P aramet ers (p.3991 ) summar ize basic and ad vanced par amet ers, respectively.These tables include 3989Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.descr iptions of the default v alues and ph ysical units , wher e applic able , for each of the CHEMKIN-CFD paramet ers, as w ell as a discussion of the r ecommended par amet er usage . Table 1: Summar y of B asic CHEMKIN-CFD P aramet ers Default ValueUsage Paramet er 0 Controls the le vel of diagnostic pr inting t o the CHEMKIN-CFD diagnostic output file , wher e 0 indic atesPrint Level no pr inting , 1 indic ates standar d pr inting , and 2 enables a v erbose le vel of pr inting tha t provides details ab out the solv er op erations . Note tha t diagnostic output c an signific antly c ontribut e to comput e time such tha t high le vels of pr inting should be avoided unless pr oblems ar e enc oun tered tha t requir e diagnosis . 1.E-8 Controls the smallest v alue of a sp ecies mass fr action that will b e tracked b y the CHEMKIN-CFD solv erAbsolute Toler- ance for Gas- phase Species convergenc e algor ithm. This should r epresen t either the smallest mass fr action tha t is of imp ortanc e in the pr oblem or , for stiff chemistr y, the smallest fraction p ertaining t o a sp ecies tha t can ha ve a signific ant eff ect thr ough chemic al reaction on other species of in terest. Typic al values r ange fr om 1.E-6 t o 1.E-12. 1.E-4 Controls the accur acy to which gas sp ecies mass fractions ar e resolv ed. Roughly this par amet er controlsRelative Toler- ance for Gas- phase Species the numb er of signific ant digits in the solution. However, this par amet er can also b e imp ortant for convergenc e of pr oblems with stiff chemistr y, as it is imp ortant to sufficien tly r esolv e sp ecies tha t ha ve a major impac t on tr ace sp ecies of in terest. Typic al values r ange fr om 1.E-3 t o 1.E-5. 1.E-8 Controls the smallest v alue of a sur face sp ecies sit e fraction tha t will b e tracked b y the CHEMKIN-CFDAbsolute Toler- ance for Surface Species solv er convergenc e algor ithm. This should r epresen t either the smallest mass fr action tha t is of imp ortanc e in the pr oblem or , for stiff chemistr y, the smallest fraction p ertaining t o a sp ecies tha t can ha ve a signific ant eff ect thr ough chemic al reaction on other species of in terest. Typic al values r ange fr om 1.E-6 t o 1.E-15. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3990Controlling CHEMKIN-CFD S olver Paramet ers U sing Text CommandsDefault ValueUsage Paramet er 1.E-4 Controls the accur acy to which sur face sp ecies sit e fractions ar e resolv ed. Roughly this par amet er controlsRelative Toler- ance for Surface Species the numb er of signific ant digits in the solution. However, this par amet er can also b e imp ortant for convergenc e of pr oblems with stiff chemistr y, as it is imp ortant to sufficien tly r esolv e sp ecies tha t ha ve a major impac t on tr ace sp ecies of in terest. Typic al values r ange fr om 1.E-3 t o 1.E-5. Table 2: Summar y of A dvanc ed CHEMKIN-CFD P aramet ers Default ValueUsage Paramet er 1 Determines which solv er to use dur ing pseudo time-st epping used t o impr ove the initial guess in aPseudo Time-step- ping Solver Op- tion cell for st eady-sta te simula tions . By default , it is set to 1 and a r obust solv er with str ict error c ontrol will be used when the st eady-sta te algor ithm r equir es time-st epping assistanc e.You ma y optionally r evert to a less accur ate time-st epping t echnique , which may be computa tionally fast er but mor e pr one t o failur e, by setting it t o zero. See Advanced P aramet ers Used in the S teady-State Solution A lgor ithm (p.3993 ) for mor e inf ormation. This par amet er is ignor ed f or transien t simula tions . 1.E-6 This option is only r elevant if the P seudo Time-st epping S olver Option is set t o 1 (the defaultPseudo Time-step- ping Size [sec onds] setting). This c ontrols the time in terval for time-st epping when time-st epping is used t o assist a steady-sta te calcula tion. See Advanced P aramet ers Used in the S teady-State Solution A lgor ithm (p.3993 ) for mor e inf ormation. A v alue of 1.E-4 sec onds is recommended f or c ombustion pr oblems . 1 This par amet er controls ho w man y iterations b etween time-st epping and st eady-sta te solution a ttempts c anMaximum Pseudo Time-stepping At- tempts be tried b efore the solv er giv es up and r egist ers a failur e for the c ell. Usually only one a ttempt is needed , but the maximum c an b e incr eased fr om this default value in difficult c ases . Note tha t in some c ases it is most efficien t to ignor e a small numb er of c ell failur es early on in the simula tion as long as these c ells recover on subsequen t iterations . See Advanced Paramet ers U sed in the S teady-State Solution Algor ithm (p.3993 ) for mor e inf ormation. A v alue of 10 to 100 is r ecommended t o minimiz e er ror messages . 1.E-2 Maximum pseudo time-st ep v alue f or time in tegration during st eady-sta te solution. This v alue is r elevant to steady-sta te simula tions only .Maximum Time Step Allowed [sec onds] 3991Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Default ValueUsage Paramet er 1.E-10 Minimum pseudo time-st ep v alue f or time in tegration during st eady-sta te solution. This v alue is r elevant to steady-sta te simula tions only .Minimum Time Step Allowed [sec onds] 0 (i.e ., not specified)Initial time-st ep v alue f or use in time in tegration. By default , the solv er will aut oma tically cho ose an appr opriate initial time st ep, which is theInitial Time Step for Solver [sec onds] recommended appr oach. In r are cases , however, control of initial time st ep v alue ma y impr ove convergenc e behavior. 1.01 Sets the upp er b ounds f or the gas-phase sp ecies mass fractions dur ing st eady-sta te solution. In some c ases ,Upper Bound for Gas-species Mass Fraction it ma y help c onvergenc e to allo w sp ecies t o go sligh tly o ver the ph ysical b ounds dur ing in terim steady-sta te iterations r ather than f orcing the b ounds to be one . -1.E-12 Sets the lo wer b ounds f or the gas-phase sp ecies mass fractions dur ing st eady-sta te solution. In some c ases ,Lower Bound for Gas-species Mass Fraction it ma y help c onvergenc e to allo w sp ecies t o go sligh tly nega tive dur ing in terim st eady-sta te iterations rather than f orcing the b ounds t o be zero. A v alue as nega tive as ab out -1.E-4 ma y be used . 1.1 Sets the upp er b ounds f or the sur face sp ecies sit e fractions dur ing st eady-sta te solution. In some c ases ,Upper Bound for Surface Site Fraction it ma y help c onvergenc e to allo w sp ecies t o go sligh tly o ver the ph ysical b ounds dur ing in terim steady-sta te iterations r ather than f orcing the b ounds to be one . -1.E-4 Sets the lo wer b ounds f or the sur face sp ecies sit e fractions dur ing st eady-sta te solution. In some c ases ,Lower Bound for Surface Site Fraction it ma y help c onvergenc e to allo w sp ecies t o go sligh tly nega tive dur ing in terim st eady-sta te iterations rather than f orcing the b ounds t o be zero. 1.E-12 This v alue will b e used t o substitut e an y non-p ositiv e species fr actions dur ing in terim st eady-sta te iterations .Small Positive Value to Replace In some c ases , setting this t o a v ery small p ositiv e Negative Species Fractions numb er ma y aid c onvergenc e for the st eady-sta te solv er. ““ Currently not used . Provided f or futur e use . Enter Auxiliary Input Filename ““ Currently not used . Provided f or futur e use . Enter Arbitrary String 0 Currently not used . Provided f or futur e use . Enter Arbitrary Value Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3992Controlling CHEMKIN-CFD S olver Paramet ers U sing Text CommandsC.1. Advanc ed P aramet ers U sed in the S tead y-State Solution A lgor ithm Many of the par amet ers list ed in Table 2: Summar y of A dvanced CHEMKIN-CFD P aramet ers (p.3991 ) are relevant only f or st eady-sta te solution. Here a br ief descr iption of the st eady-sta te solution algor ithm is pr ovided in or der t o clar ify the r ole of these par amet ers and their impac t on solution c onvergenc e. For st eady-sta te pr oblems , the ANSY S CHEMKIN-CFD solv er is c alled b y ANSY S Fluen t for each c ell dur ing each F luen t iteration t owards a st eady sta te.Within each c ell, the chemistr y solv er will a ttempt t o de- termine an appr opriate steady-sta te using a c ombina tion of a mo dified N ewton-it eration pr ocedur e and a “pseudo ” time-st epping pr ocedur e.The N ewton-it eration metho d is used t o attempt t o dir ectly iterate towards the desir ed solution. However, at ear ly times in the simula tion, this pr ocedur e ma y not succ eed, esp ecially when the initial guess is far fr om the ac tual st eady solution. In such c ases , the CHEMKIN-CFD mo dule will aut oma tically swit ch t o a time-st epping mo de t o ad vance the initial guess closer t o the ph ysical solution. After tak ing a c ertain numb er of time st eps, the N ewton-it eration algor ithm tries again. In this w ay, the st eady-sta te solution is achie ved with a minimum amoun t of time-st epping . Since time-st epping is c omputa tionally e xpensiv e, this r esults in a c omputa tionally efficien t but r obust metho d for achie ving the st eady-sta te solution. You c an c ontrol the numb er of times the CHEMKIN-CFD mo dule is allo wed t o use time-st epping t o advance a solution t owards st eady-sta te before reporting a failur e for an y individual c ell (see Maximum Pseudo Time-stepping Attempts in Table 2: Summar y of A dvanced CHEMKIN-CFD P aramet ers (p.3991 )). In p erforming the pseudo time-st epping pr ocedur e, ther e ar e two solv er options - a “basic ” time-st epping procedur e and a “robust ” time-st epping pr ocedur e (see Pseudo Time-stepping Solver Option in Table 2: Summar y of A dvanced CHEMKIN-CFD P aramet ers (p.3991 )).The “robust ” procedur e (default) uses an in tegration metho d tha t is v ery accur ate with er ror c ontrol enf orced on all solution v ariables . This c an sometimes b e mor e time c onsuming but is gener ally mor e reliable in tr acking tr ansien t sta tes towards an e ventual st eady condition. The “basic ” solv er option is much mor e appr oxima te in the time- tracking t echnique , but is of ten fast er and sufficien tly r obust f or some c ases . When the “robust ” time-st epping pr ocedur e is selec ted, you c an sp ecify the time in terval used f or each attempt t o ad vance the solution using time in tegration (S ee Pseudo Time-stepping Size in Table 2: Summar y of A dvanced CHEMKIN-CFD P aramet ers (p.3991 )).The ac tual time st eps used dur ing the time in tegration will b e aut oma tically det ermined based on the r ate of change of the solution variables .The time in terval, however, controls the t otal time ad vanced b efore retur ning the solution t o be used as the ne xt initial guess in the N ewton-it eration.metho d. In addition t o the pseudo time-st epping c ontrols, you ma y also c ontrol certain par amet ers tha t aff ect the c onvergenc e behavior of the N ewton-it eration algor ithm itself . In par ticular , you c an mo dify the solution b ounds imp osed dur ing the it erations (see Upper Bounds and Lower Bounds para- meters in Table 2: Summar y of A dvanced CHEMKIN-CFD P aramet ers (p.3991 )). By extending the b ounds sligh tly outside of the ph ysical limits , the N ewton it eration c an mor e easily r esolv e sp ecies fr actions that are very near t o those limits .This c an b e esp ecially helpful in ear ly iterations wher e variable v alues may be changing r apidly . It is also helpful t o try to “reset ” any nega tive sp ecies fr actions t o very small values b etween it erations , so tha t these v alues do not ha ve unph ysical eff ects on r eaction r ates. For this pur pose, you c an sp ecify a small p ositiv e value , which should not e xceed the sp ecified absolut e toler ance, as a r eplac emen t value f or nega tive fractions (see Small Positive Value to Replace Negative Species Fractions in Table 2: Summar y of A dvanced CHEMKIN-CFD P aramet ers (p.3991 )). 3993Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Advanced P aramet ers U sed in the S teady-State Solution A lgor ithmC.2. Setting U p M onit or C ells f or the ANSY S CHEMKIN-CFD C hemistr y Solver At the same le vel of the basic-options and ad vanced-options in the Text User In terface, tha t is, under define/models/species/CHEMKIN-CFD-parameters , you c an add , delet e, and list monitor cells . By sp ecifying a monitor cells in the CHEMKIN-CFD options , you ar e requesting additional pr intout diagnostics f or e very iteration or time-st ep a t this c ell lo cation. Such pr intout c an add signific antly t o computa tional times and should b e avoided unless ther e is a pr oblem has b een enc oun tered and mor e diagnosis is needed . Imp ortant Using monit or c ells ma y add signific antly t o the job r un time . It is r ecommended tha t mon- itor c ells only b e included if e xtra diagnosis is r equir ed t o resolv e a c onvergenc e pr oblem or lo cal mesh issue , for e xample . Monit or c ells ar e added using the add-cell-monitor option and pr oviding the ph ysical coordina tes that correspond as closely as p ossible t o the c entroid lo cation of the desir ed c ell in the F luen t mesh. You c an cr eate mor e than one c ell monit or and y ou c an b e delet e all of them using the delete-cell- monitor option .You ma y also list the cur rently ac tivated monit or c ells using the list-cell- monitor option . C.3. Diagnostic F iles and E rror M essages In addition t o the standar d ANSY S Fluen t files pr oduced dur ing a r un using the CHEMKIN-CFD solv er, the CHEMKIN-CFD mo dule cr eates sp ecial files t o hold diagnostic output and er ror messages tha t ma y be helpful in diagnosing a pr oblem with the pr e-pr ocessing or r un st eps. In addition, error messages may be wr itten in the ANSY S Fluen t Graphic al U ser In terface windo w dur ing r un-time pr ocessing . Table 3: Diagnostic Output F iles C reated D uring a CHEMKIN-CFD R un (p.3994 ) lists additional files tha t may be created b y the chemistr y solv er, the da ta pr inted t o them, and an indic ation of wher e the y are created in the ANSY S Fluen t run pr ocess. All files ar e created within the w orking dir ectory of the simu- lation r un.The ac tual names of man y of the files will dep end on v ariables , such as the chemistr y-set file names , the c ase-file name , the c ell numb er, iteration or time-st ep numb er, and the pr ocessor id . Such v ariables ar e indic ated b y < > in Table 3: Diagnostic Output F iles C reated D uring a CHEMKIN-CFD Run (p.3994 ). Table 3: Diagnostic Output F iles C reated D uring a CHEMKIN-CFD R un Contents D escr iption When F ile I s Created Filename This file echo es back the gas-phase chemistr y reaction set , species names , andAlways created dur ing pre-pr ocessing , upon.out elemen ts in f ormatted t ext. In addition, saving the CHEMKIN mechanism definition. detailed er ror messages ar e contained in this file in c ase an er ror is enc oun tered while pr ocessing the gas-phase chemistr y input file and gas-phase ther modynamic data. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3994Controlling CHEMKIN-CFD S olver Paramet ers U sing Text CommandsContents D escr iption When F ile I s Created Filename A “Link ing F ile” used t o transf er the pre-pr ocessed inf ormation t o theAlways created dur ing pre-pr ocessing , uponchem.asc CHEMKIN-CFD mo dule a t run-time .This file saving the CHEMKIN mechanism definition. is typic ally not view ed b y the user , but ma y occasionally b e request ed b y Technic al Supp ort dur ing pr oblem diagnosis . This file echo es back the sur face chemistr y reaction set and the sur face phase andCreated dur ing pre-pr ocessing , only if.out species names . In addition, detailed er ror surface chemistr y box messages ar e contained in this file in c ase is check ed in CHEMKIN mechanism definition. an er ror is enc oun tered while pr ocessing the sur face chemistr y input file and surface-sp ecies ther modynamic da ta. A “Link ing F ile” used t o transf er the pre-pr ocessed inf ormation t o theCreated dur ing pre-pr ocessing , only ifsurf.asc CHEMKIN-CFD mo dule a t run-time .This file surface chemistr y box is typic ally not view ed b y the user , but ma y is check ed in CHEMKIN mechanism definition. occasionally b e request ed b y Technic al Supp ort dur ing pr oblem diagnosis . This file echo es back the tr ansp ort-da ta fitting c oefficien ts in f ormatted t ext. InCreated dur ing pre-pr ocessing , only if.out addition, detailed er ror messages ar e transp ort-property box contained in this file in c ase an er ror is is check ed in CHEMKIN mechanism definition. encoun tered while pr ocessing the gas-phase tr ansp ort da ta. A “Link ing F ile” used t o transf er the pre-pr ocessed inf ormation t o theCreated dur ing pre-pr ocessing , only iftran.asc CHEMKIN-CFD mo dule a t run-time .This file transp ort-property box is typic ally not view ed b y the user , but ma y is check ed in CHEMKIN mechanism definition. occasionally b e request ed b y ANSY S Technic al Supp ort dur ing pr oblem diagnosis . Messages ar e wr itten t o this file tha t record the pr ogress of chemistr y-set pr e-pr ocessorCreated when the simula tion r un isKINetics- log.txt and CHEMKIN-CFD solv er.The pr inting le vel initia ted in the during the simula tion r un c an b e controlled subdirectory flu- entKINlog . by Print Level as indic ated in Table 1: Summar y of B asic CHEMKIN-CFD Paramet ers (p.3990 ). Includes debug inf ormation, including the actual input sen t into the CHEMKIN-CFDCreated f or M onit or Cells (see Setting U pKIN- CELL__.DBG cell and it eration. This inf ormation ma y be request ed b y ANSY S Technic al Supp ort when diagnosing c ell failur es.ANSY S CHEMKIN-CFD Chemistr y Solver (p.3994 )) at every iteration or time-st ep, any time tha t the Print Level (Table 1: Summar y of 3995Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Diagnostic F iles and E rror M essagesContents D escr iption When F ile I s Created Filename Basic CHEMKIN-CFD Paramet ers (p.3990 )) is >0. Also cr eated an y time tha t a c ell fails in the CHEMKIN-CFD solv er and the Print Level is >0. C.4. Error M essages P rinted in the ANSY S Fluen t Graphic al U ser In terface Advanced P aramet ers U sed in the S teady-State Solution A lgor ithm (p.3993 ) lists p ossible er ror messages that ma y app ear in the ANSY S Fluen t Graphic al U ser In terface dur ing r un using the CHEMKIN-CFD solv er.The table includes r ecommended ac tions tha t ma y help r esolv e or nar row do wn the pr oblem. In some c ases , you ma y be referred t o some of the additional diagnostic output files gener ated b y the CHEMKIN-CFD mo dule and list ed in Table 3: Diagnostic Output F iles C reated D uring a CHEMKIN-CFD Run (p.3994 ). Table 4: Error M essages tha t May Be Printed t o the F luen t GUI Value Setting Verify the filename and file pa th for the gas-phase chemistr y input file in the Imp ortCannot read gas-phase chemistry input file. CHEMKIN F ormat Mechanism dialo g box and re-imp ort. Verify the filename and file pa th for the sur face chemistr y input file in the Imp ort CHEMKIN Format Mechanism dialo g box and r e-imp ort.Cannot read surface chemistry input file. Verify the filename and file pa th for the ther modynamic da ta file in the Imp ortCannot read thermodynamic data file. CHEMKIN F ormat Mechanism dialo g box and re-imp ort. Verify the filename and file pa th for the transp ort-property da ta file in the Imp ortCannot read transport properties data file. CHEMKIN F ormat Mechanism dialo g box and re-imp ort. Check the .out file in the w orking dir ectory for er ror messages .Cannot read gas-phase chemistry linking data file during gas- phase pre-processing. Check the .out file in the w orking dir ectory for er ror messages .Cannot read gas-phase chemistry linking data file during surface pre-processing. Check the .out file in the w orking dir ectory for er ror messages .Cannot read gas-phase chemistry linking data file during trans- port pre-processing. Check the .out file in the w orking dir ectory for er ror messages .Cannot read surface chemistry linking data file during surface pre-processing. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3996Controlling CHEMKIN-CFD S olver Paramet ers U sing Text CommandsValue Setting Check the .out file in the w orking dir ectory for er ror messages .Cannot read transport properties linking data file during trans- port pre-processing. Check file p ermissions on w orking dir ectory and mak e sur e tha t ther e is only oneCannot write gas-phase chemistry output file. CHEMKIN-CFD pr ocess using these files a t a time . Check file p ermissions on w orking dir ectory and mak e sur e tha t ther e is only oneCannot write surface chemistry output file. CHEMKIN-CFD pr ocess using these files a t a time . Check file p ermissions on w orking dir ectory and mak e sur e tha t ther e is only oneCannot write transport properties output file. CHEMKIN-CFD pr ocess using these files a t a time . Check file p ermissions on w orking dir ectory and mak e sur e tha t ther e is only oneCannot write gas-phase chemistry linking data file. CHEMKIN-CFD pr ocess using these files a t a time . Check file p ermissions on w orking dir ectory and mak e sur e tha t ther e is only oneCannot write surface chemistry linking data file. CHEMKIN-CFD pr ocess using these files a t a time . Check file p ermissions on w orking dir ectory and mak e sur e tha t ther e is only oneCannot write transport properties linking data file. CHEMKIN-CFD pr ocess using these files a t a time . Verify gas-phase chemistr y file pa th in the CHEMKIN M echanism definition and r e-imp ort the chemistr y files .Gas-phase chemistry file is NULL. Verify sur face-chemistr y file pa th in the CHEMKIN M echanism definition and r e-imp ort the chemistr y files .Surface chemistry file is NULL. Verify ther modynamic-da ta file pa th in the CHEMKIN M echanism definition and r e-imp ort the chemistr y filesThermodynamic data file is NULL. Verify tr ansp ort-da ta file pa th in the CHEMKIN Mechanism definition and r e-imp ort the chemistr y files .Transport properties data file is NULL. Check the .out file in the w orking dir ectory for er ror messages .Failure in pre-processing of gas- phase chemistry mechanism. Check the .out file in the w orking dir ectory for er ror messages .Failure in pre-processing of surface chemistry mechanism. Check the .out file in the w orking dir ectory for er ror messages .Failure in pre-processing of transport properties. 3997Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Error M essages P rinted in the ANSY S Fluen t Graphic al User In terfaceValue Setting Check t o see if the ANSY S Fluen t solution has diverged or has unph ysical values f or theFailure in CHEMKIN Gas-phase library call. variables .Try tur ning Print Level > 0 and setting a monit or c ell t o obtain mor e information. Check t o see if the ANSY S Fluen t solution has diverged or has unph ysical values f or theFailure in CHEMKIN Surface lib- rary call. variables .Try tur ning Print Level > 0 and setting a monit or c ell t o obtain mor e information. Check t o see if the ANSY S Fluen t solution has diverged or has unph ysical values f or theFailure in CHEMKIN Transport library call. variables .Try tur ning Print Level > 0 and setting a monit or c ell t o obtain mor e information. Re-imp ort the CHEMKIN chemistr y set and mak e sur e it is selec ted in the Species M odel dialo g box (under Setup /Models ).Need to run CHEMKIN-CFD PrePro- cess first. Either de-selec t the Sur face Chemistr y option in the Imp ort CHEMKIN F ormat MechanismNo surface data for the chemistry set. dialo g box, or mak e sur e tha t a v alid sur face chemistr y file is indic ated. Either de-selec t the Transp ort Data option in the Imp ort CHEMKIN F ormat MechanismNo transport data for the chem- istry set. dialo g box, or mak e sur e tha t a v alid tr ansp ort data file is indic ated. Check file p ermissions on the w orking dir ectory and mak e sur e tha t ther e is only oneFailure in writing data into the diagnostics file. CHEMKIN-CFD pr ocess using these files a t a time . Check the KINetics-log.txt file in the subdirectory fluentKINlog for er rorError in CHEMKIN-CFD model, see diagnostic output file for de- tails. messages . See Error M essages P rinted in the ANSY S Fluen t Graphic al U ser In terface (p.3996 ) for mor e inf ormation. C.5. Diagnostic M essages in the KINetics-log.txt File The KINetics-log.txt file is a “catch-all ” for man y diagnostic messages tha t are gener ated b y the CHEMKIN-CFD mo dule .The most c ommon t ypes of messages ar e er ror messages r elated t o setup or cell c onvergenc e. Cell-c onvergenc e er ror messages c an tak e a v ariety of f orms.The most c ommon ar e summar ized in Table 5: Other E rror M essages in KINetics-log.txt (p.3999 ). In gener al, if ther e ar e just a f ew failed cells a t the b eginning of a simula tion it is saf e to ignor e them. When the numb er of failed c ells c ontinues to gr ow with each it eration, ther e is lik ely an issue with the pr oblem set-up or with the chemistr y da ta. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 3998Controlling CHEMKIN-CFD S olver Paramet ers U sing Text CommandsTable 5: Other E rror M essages in KINetics-log.txt (p.3999 ) contains some br oad suggestions of ways to impr ove cell-c onvergenc e behavior based on the t ype of c ell failur e message r eceived. Table 5: Other E rror M essages in KINetics-log.txt Rec ommended A ction Error M essage Most lik ely suggests an er ror in setting the convergenc e cr iteria (tha t is absolut e andFAILURE INITIALIZING SETTINGS FOR THE KINetics STEADY-STATE GAS- PHASE CHEMISTRY SOLVER relative toler ance) and the pseudo-st eady-sta te time st epping par amet ers. Check tha t the user-pr ovided v alues ar e reasonable . Indic ates tha t a c onvergenc e pr oblem w as encoun tered dur ing st eady-sta te solution,WARNING: Exceeded allowed time- stepping intervals in cell wher e time-st epping is used t o help ad vance the st eady-sta te iterations . In this c ase, you c an either ignor e the message (see if the c ell convergenc e recovers in subsequen t iterations) or tr y to incr ease either the time in terval or the numb er of allo wed time-st epping in tervals (See Table 2: Summar y of A dvanced CHEMKIN-CFD P aramet ers (p.3991 ) for mor e information). Indic ates tha t the c ell failed t o converge (either steady-sta te or tr ansien t).In this c ase, you c anKINETICS ERROR: SOLUTION FAILED either ignor e the message (see if the c ell convergenc e recovers in subsequen t iterations) or tr y to mo dify some of the user-c ontrolled paramet ers t o impr ove convergenc e (S ee Table 2: Summar y of A dvanced CHEMKIN-CFD Paramet ers (p.3991 ) for mor e inf ormation). Indic ates tha t the pr oblem is difficult t o converge so tha t the tr ansien t solv er is tak ingWarning - The transient chemistry solver tried 500 steps without extra steps. However, it is only a w arning and convergence in this cell; 500 more steps will be allowed the c ell has not ac tually failed . If you r eceive an e xcessiv e numb er of these messages , try reducing the absolut e or r elative solution toler ances tha t control the CHEMKIN-CFD solv er. Indic ates a p ossible er ror in the pr e-pr ocessing of the gas-phase chemistr y input file . CheckKINETICS ERROR: Problem getting species names; Check that the the .out file f or er ror messages .CHEMKIN files have been processed correctly Indic ates a p ossible er ror in the pr e-pr ocessing of the sur face chemistr y input file . Check theKINETICS ERROR: Problem getting surface chemistry info; Check .out file f or er ror messages .that the CHEMKIN files have been processed correctly These messages ar e from the CHEMKIN-CFD transien t solv er, DASPK. The e xact messageDASPK:... 3999Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Diagnostic M essages in the KINetics-log.txt FileRec ommended A ction Error M essage usually c ontains mor e inf ormation ab out the problem. Note During st eady-sta te simula tions , onc e an it eration o ccurs wher e ther e ar e no failed c ells, the effect of pr eviously failed c ells in ear lier it erations is c omplet ely er ased . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4000Controlling CHEMKIN-CFD S olver Paramet ers U sing Text CommandsAppendix D . Nomencla ture Area (m2, ft2) Acceleration (m/s2, ft/s2) Local sp eed of sound (m/s , ft/s) Concentration (mass/v olume , moles/v olume) Drag c oefficien t, defined diff erent ways (dimensionless) Heat capacit y at constan t pressur e, volume ( J/kg-K, Btu/lbm- °F) , Diamet er; dpDp, par ticle diamet er (m, ft) Hydraulic diamet er (m, ft) Mass diffusion c oefficien t (m2/s, ft2/s) Total ener gy, activation ener gy (J, kJ, cal, Btu) Mixture fraction (dimensionless) Force vector (N, lbf) Drag f orce (N, lbf) Gravitational acc eleration (m/s2, ft/s2); standar d values = 9.80665 m/s2, 32.1740 f t/s2 Grashof numb er ratio of buo yancy forces to visc ous f orces (dimensionless) Gr Total en thalp y (ener gy/mass , ener gy/mole) Heat transf er coefficien t (W/m2-K, Btu/f t2-h- °F) Species en thalp y; h0, standar d sta te en thalp y of f ormation (ener gy/mass , ener gy/mole) Radia tion in tensit y (ener gy per ar ea of emitting sur face per unit solid angle) Mass flux; diffusion flux (k g/m 2-s, lbm/ft2-s) Equilibr ium c onstan t = f orward rate constan t/back ward rate constan t (units v ary) Kinetic ener gy per unit mass ( J/kg, Btu/lb m) Reaction r ate constan t, for e xample , , , , (units v ary) Thermal c onduc tivit y (W/m-K, Btu/f t-h- °F) Boltzmann c onstan t ( J/molecule-K) Mass tr ansf er coefficien t (units v ary); also , , Length sc ale (m, cm, ft, in) Lewis numb er ratio of ther mal diffusivit y to mass diffusivit y (dimensionless) Le Mass (g , kg, lbm) 4001Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Mass flo w rate (kg/s, lbms) Molecular w eigh t (kg/kmol, lbm/lbmmol) Mach numb er ratio of fluid v elocity magnitude t o lo cal sp eed of sound (dimensionless) M Nusselt numb er dimensionless hea t transf er or mass tr ansf er coefficien t (dimensionless); usually a func tion of other dimensionless gr oupsNu Pressur e (P a, atm, mm Hg , lbf/ft2) Peclet numb er for hea t transf er, and for mass tr ansf er (dimensionless) Pe Prandtl numb er ratio of momen tum diffusivit y to ther mal diffusivit y (dimensionless) Pr Flow rate of en thalp y (W, Btu/h) Heat flux ( W/m2, Btu/f t2-h) Gas-la w constan t (8.31447 J/kmol-K, 1.98588 Btu/lbmmol- °F) Radius (m, ft) Reaction r ate (units v ary) Rayleigh numb er ; measur e of the str ength of buo yancy-induc ed flo w in na tural (fr ee) convection (dimensionless)Ra Reynolds numb er ratio of iner tial f orces to visc ous f orces (dimensionless) Re Total en tropy (J/K, J/kmol-K, Btu/lbmmol- °F) Species en tropy; s0, standar d sta te en tropy (J/kmol-K, Btu/lbmmol- °F) Schmidt numb er ratio of momen tum diffusivit y to mass diffusivit y (dimensionless) Sc Mean r ate-of-str ain t ensor (s-1) Temp erature (K, °C, °R, °F) Time (s) Free-str eam v elocity (m/s , ft/s) Velocity magnitude (m/s , ft/s); also wr itten with dir ectional subscr ipts (f or e xample , vx, vy, vz, vr) Volume (m3, ft3) Overall v elocity vector (m/s , ft/s) Weber numb er ratio of aer odynamic f orces to sur face tension f orces (dimensionless) We Mole fr action (dimensionless) Mass fr action (dimensionless) Permeabilit y, or flux p er unit pr essur e diff erence (L/m2-h-a tm, ft /ft2-h-(lbf/ft2)) Thermal diffusivit y (m2/s, ft2/s) Volume fr action (dimensionless) Coefficien t of ther mal e xpansion (K ) Porosity (dimensionless) Ratio of sp ecific hea ts, cp/cv (dimensionless) Change in v ariable , final initial (f or e xample , Δp, Δt, ΔH, ΔS, ΔT) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4002Nomencla tureDelta func tion (units v ary) Emissivit y (dimensionless) Lennar d-Jones ener gy par amet er (J/molecule) Turbulen t dissipa tion r ate (m2/s3, ft2/s3) Void fr action (dimensionless) Effectiveness fac tor (dimensionless) Rate exponen ts for reactants, produc ts (dimensionless) , Radia tion t emp erature (K) Molecular mean fr ee pa th (m, nm, ft) Wavelength (m, nm, Å, ft) Dynamic visc osity (cP , Pa-s, lbm/ft-s) Kinema tic visc osity (m2/s, ft2/s) Stoichiometr ic coefficien ts for reactants, produc ts (dimensionless) , Densit y (kg/m3, lbm/ft3) Stefan-B oltzmann c onstan t (5.67x10-8W/m2-K4) Surface tension (k g/m, dyn/cm, lbf/ft) Scattering c oefficien t (m-1) Stress t ensor (P a, lbf/ft2) Shear str ess (P a, lbf/ft2) Time sc ale, for e xample , , , (s) Tortuosit y, char acteristic of p ore str ucture (dimensionless) Equiv alenc e ratio (dimensionless) Thiele mo dulus (dimensionless) Angular v elocity; , Mean r ate of r otation t ensor (s-1) Specific dissipa tion r ate (s-1) Solid angle (degr ees, radians , gradians) Diffusion c ollision in tegral (dimensionless) 4003Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4004Biblio graph y Imp ortant Under U.S. and in ternational c opyright law, ANSY S, Inc. is unable t o distr ibut e copies of the pap ers list ed in the biblio graph y, other than those published in ternally b y ANSY S, Inc. Use your libr ary or a do cumen t deliv ery ser vice to obtain c opies of c opyrighted pap ers. [1] CRANIUM, Version 1.0 .Molecular K nowledge S ystems , Inc., Bedford, NH. 2007. [2] FIELD VIEW R eferenc e Manual, Software Release Version 10 .Intelligen t Ligh t.2004. [3] KIN etics f or F luent ,Version 2.4 .Reaction D esign, Inc., San D iego , CA.2009. [4] VdmT ools P rogrammer Manual, Version 3.2.0 .Visual K inema tics, Inc.2005. [5] T. Ahmad , S. L. Plee, and J. P. 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"An Efficient C omputational Mo del f or P remix ed Turbulent C ombustion at High R eynolds N umb ers B ased on a Turbulent F lame S peed C losur e".J. of Gas Turbines P ower.120. 526–532. 1998. [148] Driver, D.M., (1991): "Reynolds S hear S tress M easur emen ts in a S epar ated B oundar y La yer F low", AIAA 22nd F luid D ynamics , Plasma D ynamics and Laser C onference, AIAA-91-1787. . [149] F.R. Menter."Two-Equation E ddy-Viscosit y Turbulenc e Mo dels f or E ngineer ing A pplic ations" .AIAA Journal .32(8). 1598–1605. August 1994. [150] Bell, J. H. & M ehta, R. D., (1990): "Developmen t of a t wo-str eam mixing la yer fr om tr ipped and untripped b oundar y layers", AIAA J., vol. 28, no.12, pp. 2034-2042.. [151] Vogel, J.C. & E aton, J.K., (1985): "Combined H eat Transf er and F luid D ynamic M easur emen ts Downstr eam of a B ackward-Facing S tep", Vol. 107, Journal of H eat Transf er, pp. 922 – 929.. [152] Bradbur y, L.J.S., (1965), “The S tructure of a S elf-P reser ving P lane J et”, Journal of F luid M echanics Vol. 23, pp.31-64. . [153] Wygnansk i, I. and F iedler , H.E ., (1968), “Some M easur emen ts in the S elf-P reser ving J et”, Boeing Scien tific R esear ch Labs , Documen t D1-82-0712. . 4013Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4014Part IV: Applic ation C lien ts The sec tion descr ibes ho w to use ANSY S Fluen t applic ation clien ts. •Remot e Visualiza tion and A ccessing F luen t Remot ely (p.4017 ), descr ibes the use of the ANSY S Fluen t Remot e Visualiza tion C lient. •Fluen t Icing (p.4037 ), descr ibes the use of the ANSY S Fluen t Icing C lient.Chapt er 1: Remot e Visualiza tion and A ccessing F luen t Remot ely Using the ANSY S Fluen t Remot e Visualiza tion C lient you c an star t a visualiza tion clien t session tha t can be used t o connec t to up t o six in teractive or ba tch (Linux only) solv er sessions on r emot e machines . From the r emot e session y ou c an: •Extract simula tion da ta and visualiz e results using mesh, contour and v ector plots . •Monit or solution c onvergenc e using r esidual and monit or plots . •Modify solution settings and star t/pause/in terrupt the c alcula tion. •Send an y text command t o the ser ver. 1.1. Starting Remot e Visualiza tion If you ha ve multiple r eleases of ANSY S pr oduc ts installed on y our machine(s), ensur e that the ser ver and the remot e visualization client ar e from the same r elease , to avoid any une xpected b eha vior . 1.1.1. Steps f or S tarting the S erver Before you star t and c onnec t a r emot e clien t session, the ser ver has t o be running . 1.Start the ser ver in the ANSY S Fluen t session. a.Launch ANSY S Fluen t. b.Start the ser ver. File → Applic ations → Server → Start... 2.Specify the name of the ser ver inf o file and its st orage dir ectory.The default name of server_info- .txt is supplied . Note For clust ers with isola ted c omput e no des (f or e xample , a C ray sy stem) y ou must use the export REMOTING_SERVER_ADDRESS environmen t variable t o pr ovide an out ward facing IP addr ess f or the clien t to connec t to.This en vironmen t variable must b e defined on b oth the ser ver and the clien t. Alternat e Metho ds for Star ting the R emot e Visualization S erver Here ar e a f ew mor e ways tha t you c an star t a ser ver session. 4017Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.•The -sifile=server_info_example_name.txt command line star tup option. Note You c an sp ecify the lo cation f or the ser ver inf o file pr ior t o the filename , for e xample -sifile=D:/example_folder/server_info_example_name.txt . If you do not pr ovide a file pa th b efore the file name and y ou do not pr ovide a pa th using the SERVER_INFO_DIR environmen t variable , then the file is sa ved in y our w orking dir ectory. •From pr ogress bar b y click ing Start Server. Figur e 1.1: Progress B ar with S tart Server Option •Launch Fluen t Remot e Visualiza tion C lien t from the star t menu . Right-click the Remot eSession-1 branch of the tr ee and selec t Start Server. •Enter the server/start-server text command in to the c onsole of a r unning F luen t session. 1.1.1.1. Port Management When launching the ser ver, you ha ve the option sp ecify a r ange of p orts.There must b e at least t wo ports available fr om the r ange y ou supplied f or the ser ver to star t, other wise it will not launch. Note that using this en vironment v ariable is optional, so if it is not declar ed, the ser ver uses r andom p orts. Use the REMOTING_PORTS environmen t variable t o sp ecify the p orts for star ting the ser ver:REMOT- ING_PORTS=/portspan= • and must b e valid in tegers • must b e gr eater than 1 • must b e gr eater than 0 Example: If you sp ecify REMOTING_PORTS=2678/portspan=3 , then only 3 p orts ar e available:2678 ,2679 , 2680 . Each ser ver requir es two ports, so 2678 and 2679 are consumed when y ou launch the ser ver. If you then tr y to star t another ser ver on the same machine , it will not star t as ther e is only one p ort (2680 ) available . 1.1.2. Steps F or S tarting the Remot e Visualiza tion C lien t 1.Start the ser ver in the ANSY S Fluen t session, as descr ibed in Steps f or S tarting the S erver (p.4017 ). 2.Start the R emot e Visualiza tion C lient (2 options): •Scenar io—R emot e Client is on a diff erent machine than the ser ver. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4018Remot e Visualiza tion and A ccessing F luen t Remot elya.(Windo ws) Launch Fluen t Remot e Visualiza tion C lien t from the star t menu . (Linux) Launch the F luen t Remot e Visualiza tion C lient from installation_drive/Program Files/ANSYS Inc/v195/fluent/bin/flremote . b.Click in the Server Inf o Filename field (highligh ted in y ellow in the Properties windo w), then click Browse.... c.Selec t the ser ver inf ormation file and click Open. d.Connec t to the ser ver session b y click ing Connec t in the Actions ribbon tab ( Connec tion group box). Actions → Connec tion → Connec t •Scenar io—R emot e Client is on the same machine as the ser ver. Start the r emot e clien t from the ser ver session. File → Applic ations → Visualiza tion C lien t The client will aut omatic ally connec t to the ser ver b y loading the Server Info F ilename . Note For clust ers with isola ted c omput e no des (f or e xample , a C ray sy stem) y ou must use the export REMOTING_SERVER_ADDRESS environmen t variable t o pr ovide an out ward facing IP addr ess f or the clien t to connec t to.This en vironmen t variable must b e defined on b oth the ser ver and the clien t. Imp ortant The clien t and ser ver machines must b e able t o connec t by using their IP addr esses .You can c onfir m tha t the machines c an c onnec t using IP addr esses b y ensur ing tha t the ping command w orks fr om b oth ser ver to clien t and clien t to ser ver. Alternat e Metho ds for Star ting the R emot e Visualization C lient •You c an star t the clien t from pr ogress bar b y click ing Start clien t. Figur e 1.2: Progress B ar with S tart Clien t Option Star t Client will onl y app ear as an option when ther e is not a R emot e Visualization C lient alr ead y con- nec ted t o the ser ver. •Enter the server/start-client text command in to the c onsole of a r unning F luen t session. 4019Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Starting R emot e Visualiza tion1.2. Using a J ob Scheduler with Remot e Visualiza tion You ha ve the option t o use job schedulers in c oordina tion with the R emot e Visualiza tion C lient and server. Job schedulers ar e pr imar ily c overed in Setting P arallel Scheduler Options in F luen t Launch- er (p.3051 ), however, ther e ar e some nuanc es for using a job scheduler with r emot e visualiza tion. There ar e thr ee t ypes of ser ver-clien t connec tions tha t you c an mak e: •Start the clien t and ser ver separ ately •Start the clien t from the ser ver •Start the ser ver fr om the clien t The only t ype of c onnec tion tha t ma y requir e an additional st ep f or remot e visualiza tion is when star ting the ser ver fr om the clien t. For this c ase y ou must define the SERVER_INFO_DIR environmen t variable on b oth the ser ver and the clien t machines . Set the en vironmen t variable t o a lo cation tha t is acc essible for b oth the ser ver and the clien t. (Linux only) F luen t aut oma tically selec ts the b est gr aphics dr iver and defaults t o using the X11 gr aphics driver when it do es not det ect the r equir ed gr aphics supp ort.You c an use the HOOPS_PICTURE envir- onmen t variable t o force a par ticular gr aphics dr iver, if y ou f eel it is nec essar y to use an alt ernate dr iver. Note SGE do es not supp ort star ting the ser ver fr om the clien t. 1.3. Op erating in the F luen t Remot e Visualiza tion E nvironmen t Onc e you ar e in the F luen t Remot e Visualiza tion C lient you c an displa y mesh, contours and v ectors, modify solution settings (as long as the ser ver is not c alcula ting), star t, pause , and in terrupt c alcula tions , and send c ommands . 1.3.1. Adding N ew Remot e Clien t Connec tions From within a c onnec ted r emot e clien t session y ou c an c onnec t to up-t o 5 other ser vers (a single r emot e clien t can b e connec ted t o a maximum of 6 ser vers). 1.Click New C onnec tion... in the Actions ribbon tab ( Connec tions group b ox). Actions → Connec tion → New C onnec tion... This cr eates a ne w br anch in the tr ee f or the ne w remot e session c onnec tion. 2.Connec t to the new ser ver—t wo sc enar ios: •Connec t to an alr ead y-running F luen t ser ver a.Selec t the newly cr eated sub-br anch in the tr ee. b.Click in the Server Inf o Filename field (highligh ted in y ellow in the Properties windo w), then click Browse.... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4020Remot e Visualiza tion and A ccessing F luen t Remot elyc.Selec t the ser ver inf ormation file and click Open. d.Connec t to the ser ver session b y click ing Connec t in the Actions ribbon tab ( Connec tion group box). Actions → Connec tion → Connec t •New ser ver on the same machine as the clien t a.Right-click the new sub-br anch in the tr ee and selec t Start Server. b.Specify the appr opriate settings in the F luen t Launcher and click OK to launch ANSY S Fluen t.The new F luent session is aut omatic ally connec ted t o the client . 1.3.2. Initializing , Starting , Pausing , and In terrupting the C alcula tion You ha ve the abilit y to initializ e, star t, pause , and in terrupt a c alcula tion fr om the R emot e Visualiza tion Client.The butt ons f or these ac tions ar e lo cated in the Actions ribbon tab . •Initializ e—fills the flo w field with an initial "guess" f or the solution. •Calcula te—begins the pr ocess of F luen t calcula ting the solution. •Pause —"pauses" the c alcula tion a t the end of the it eration and w aits f or y our input. When y ou click Resume , Fluen t continues c alcula ting fr om wher e it w as paused . For e xample , if y ou r equest 10 it erations and pause a t the 4th it eration, when y ou click Resume , Fluen t will c alcula te for the r emaining 6 it erations . If you ar e running fr om a scr ipt/jour nal file ,Pause just "pauses" the r un and all r emaining c ommands will b e execut ed when y ou click Resume . Note Do not swit ch fr om st eady-sta te to transien t (or visa-v ersa) or change mo dels when the calcula tion is paused . •Resume —continues F luen t calcula ting the solution fr om the p oint wher e it w as paused . •Interrupt—st ops the c alcula tion and tak es the solv er out of the it eration lo op.You must then click Calcula te after adjusting the r emaining it erations/time-st eps. For e xample , if y ou r equest 10 it erations and in terrupt a t the 4th it eration, when y ou click Calcula te, Fluen t will c alcula te for 10 additional it erations (14 it erations t otal). If you ar e running fr om a scr ipt/jour nal file ,Interrupt will c ancel the r un and the r emaining c ommands will not b e execut ed. 4021Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Operating in the F luen t Remot e Visualiza tion En vironmen tFigur e 1.3: Actions R ibbon Tab Selec t the Run C alcula tion branch in the tr ee t o mo dify the Properties of Remot eSession-X: Run Calcula tion . Figur e 1.4: Run C alcula tion P roperties Imp ortant Do not star t calcula tions fr om the Send C ommand t o Server dialo g box—the y must b e started using the GUI on the clien t. 1.3.3. Modifying S olution S ettings When c alcula tions ar e stopp ed or paused , you c an mo dify solution metho ds, solution c ontrols, and convergenc e cr iteria fr om the R emot e Visualiza tion C lient. To mo dify the solution metho ds or c ontrols: 1.Selec t Metho ds or Controls in the tr ee.This op ens the Properties of R emot e Session-X: Metho ds or Properties of R emot e Session-X: Contr ols. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4022Remot e Visualiza tion and A ccessing F luen t Remot elyFigur e 1.5: Example S olution M etho ds Figur e 1.6: Example S olution C ontrols 2.Modify the solution metho ds and c ontrols as r equir ed.Modified settings ar e aut omatic ally synched with the ser ver. To mo dify c onvergenc e conditions: 1.Selec t Residuals in the tr ee.This op ens the Properties of R emot e Session-X: Residuals or Properties of Remot e Session-X: Contr ols. 4023Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Operating in the F luen t Remot e Visualiza tion En vironmen tFigur e 1.7: Example Residuals P roperties 2.Modify the c onvergenc e conditions as r equir ed.Modified settings ar e aut omatic ally synched with the ser ver. 1.3.4. Graphics O bjec ts The r emot e clien t can acc ess, displa y, and edit gr aphics objec ts tha t are defined on the ser ver.You can also cr eate lo cal gr aphics objec ts on the clien t. The f ollowing sec tions descr ibe op erations a vailable f or gr aphics objec ts in the F luen t Remot e Visual- ization C lient. 1.3.4.1. Creating and D ispla ying G raphics objec ts 1.3.4.2. Modifying the Views 1.3.4.3. Synchr onizing with the S erver 1.3.4.1. Creating and D ispla ying Gr aphics objec ts 1.Click New M esh... ,New C ontour...New Vector...,New P athlines ..., or New P article Tracks ... in the Actions ribbon tab ( Graphics group b ox). Actions → Graphics → New M esh... | N ew C ontour... | N ew Vector... | N ew P athlines ... | New P article Tracks ... You c an also cr eate ne w gr aphics objec ts b y right-click ing Meshes ,Cont ours ,Vectors,Pathlines , and Particle Tracks in the tr ee and selec ting New.... Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4024Remot e Visualiza tion and A ccessing F luen t Remot ely2.Specify all of the r equir ed fields in the Properties of Remot eSession-X: . Figur e 1.8: Example G raphics O bjec t Properties 3.Click Displa y in the Actions ribbon tab ( Graphics group b ox). Note You c an r emo ve a gr aphics objec t from the r emot e clien t session b y right-click ing it in the Outline View tr ee and selec ting Remo ve. 1.3.4.2. Mo difying the Views You c an change ho w gr aphics objec ts ar e displa yed in the gr aphics windo w of the R emot e Visualiza tion Client dir ectly in the gr aphics windo w and via the Viewing ribbon tab . 4025Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Operating in the F luen t Remot e Visualiza tion En vironmen tFigur e 1.9: Viewing R ibbon Tab 1.3.4.3. Synchr onizing with the S erver When changes ar e made t o gr aphics objec ts on the ser ver or the clien t, ther e ar e options (a vailable on a r ight-click of the objec t in the tr ee) t o: •Send t o ser ver sends changes made t o the selec ted gr aphics objec t in the clien t to the ser ver. •Retr ieve from ser ver updates the gr aphics objec t in the clien t to ma tch the sta te of the same objec t on the ser ver. •View diff erenc es prints the diff erences b etween the ser ver and clien t versions of the gr aphics objec t to the c onsole . Arrows ne xt to the gr aphics objec t indic ate the sta te of the objec t. A single up ward-pointing ar row ( ) indic ates tha t this gr aphics objec t is unique t o the clien t. A do wnw ard-pointing ar row pair ed with an up ward pointing ar row ( ) indic ates tha t the same objec t has diff erent properties b etween the server and the clien t. Note Changes (new gr aphics objec ts and mo dified objec t settings) sen t from the clien t to the server while the ser ver is solving ma y not app ear in the ser ver un til af ter the solving complet es. 1.3.5. Messaging and Text Commands Fluen t communic ates with y ou when y ou ar e in the R emot e Visualiza tion C lient thr ough messages printed in the Console and the Remot eSession-X tabs . Gener ally, contents pr inted in the Console tab ar e related t o the r emot e clien t session, but not nec essar ily to a sp ecific r emot e ser ver connec tion, wher eas the Remot eSession-X tab(s) only apply t o the ser ver session tha t the y are connec ted t o. It is imp ortant to check b oth messaging tabs t o ensur e tha t you ar e getting all the inf ormation F luen t is shar ing with y ou.The Console is also a P ython 2.7 in terpreter—r efer to Python, Scripting and Transcr ipts in the R emot e Client (p.4030 ) for additional inf ormation. There ar e two ways tha t you c an en ter text commands fr om the F luen t Remot e Visualiza tion C lient. •Through the c onsole—only c ontrols the clien t session (no eff ect on the ser ver) and pr ovides options t o exit the session and mo dify the view s. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4026Remot e Visualiza tion and A ccessing F luen t Remot ely•Through the Send C ommand t o Server dialo g box—sends c ommands t o the ser ver.This option off ers all of the c ommands list ed in the Fluen t Text Command List . Imp ortant Do not star t calcula tions fr om the Send C ommand t o Server dialo g box—the y must b e started using the GUI on the clien t. Note If the ser ver is r unning with the ac tive GUI pr esen t, some c ommands , such as changing the discr etiza tion scheme , ma y requir e a r efresh of the task page displa ying the eff ected field on the ser ver (Solution M etho ds in the e xample of a mo dified discr etiza tion scheme) before the change app ears in the GUI—the changed field is still applied e ven if y ou do not up date the GUI displa y. To send t ext commands t o the ser ver: 1.Open the Send C ommand t o Server dialo g box by click ing Send C ommand ... in the Actions ribbon tab (Connec tion group b ox). Actions → Connec tion → Send C ommand ... 2.Enter the t ext command in to the Command text en try box. Note If you w ant the t ext command t o be run in the back ground without the clien t waiting for it t o complet e, then y ou c an add an & to the end of the c ommand .For e xample , define/units velocity cm/s 0.01& . Figur e 1.10: Example of S ending a C ommand: Changing the Velocity Units t o cm/s 4027Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Operating in the F luen t Remot e Visualiza tion En vironmen t3.Click Send . Imp ortant •While F luen t is solving , do not en ter an y commands tha t mo dify F luen t, such as changing equa tions , plots , mo dels , and so on, as this c ould c ause er rors. •Ensur e tha t you only en ter complet e TUI c ommands in the Send C ommand t o Server dialo g box. •Confir m tha t you ar e sending the c ommand t o the in tended ser ver if y ou ar e connec ted t o multiple ser vers.The r emot e session tha t is sending the c ommand is list ed under Remot e Session Name . Selec t a r emot e session in the tr ee to review its pr operties, which includes the name of the host machine (ser ver). •As not ed in the Warning dialo g box tha t app ears , commands ar e execut ed immedia tely in the solv er session without c onfir mation. This c ould c ause a loss of w ork, if other users ar e connec ted to and mo difying the same session as y ou. •For an y ac tions sen t from the R emot e Visualiza tion C lient to the ser ver (initializa tion, star ting calcula tion, text commands using Send C ommand t o Server), text prompts ar e aut oma tically answ ered. For e xample , if the question is The curr ent data has not b een sa ved. OK t o disc ard? ANSY S Fluen t aut oma tically answ ers OK to this question and b egins c alcula ting . 1.3.6. Saving C ase and D ata F iles You c an wr ite case and da ta files fr om the clien t. Actions → Connec tion → Write Case... | Write D ata... | Write Case & D ata... Figur e 1.11: Writing C ase and/or D ata fr om the C lien t Writing a c ase and/or da ta file: 1.Click Write Case...,Write Data... , or Write Case and D ata... . 2.Enter the name and lo cation wher e the file(s) will b e sa ved in the File name field . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4028Remot e Visualiza tion and A ccessing F luen t Remot ely3.(Optional) Enable Write binar y files to wr ite binar y files inst ead of t ext files .Binar y files tak e up less spac e and F luent c an r ead them and wr ite them fast er than t ext files . 4.(Optional) Enable Overwrite file if e xist if you w ant Fluen t to wr ite the new c ase and/or da ta files , even if this means o verwriting e xisting files with the same name in the lo cation tha t you sp ecified . 5.Click Write to sa ve the file(s). 1.3.7. Disconnec ting the S erver and C lien t If you w ant to br eak a ser ver-clien t connec tion y ou c an acc omplish this in t wo ways: from within the clien t and fr om within the ser ver. Note If the ser ver is closed une xpectedly , for e xample , the pr ocess is ended fr om the Windo ws Task M anager , the r emot e visualiza tion clien t ma y app ear t o hang , however af ter a time out the clien t will b ecome r esponsiv e again. 1.3.7.1. Disconnec ting fr om Within the R emot e Client S ession To disc onnec t from within the clien t: 1.Selec t the Remot eSession-X connec tion tha t you w ant to br eak in the tr ee. 2.Click Disconnec t in the Actions ribbon tab ( Connec tion group b ox). Actions → Connec tion → Disconnec t You c an also disc onnec t the session b y right-click ing the Remot eSession-X branch in the tr ee and selec ting Disconnec t. Imp ortant Do not tr y to close the ser ver via the exit command in the Send C ommand t o Server dialo g box, the c orrect command is (exit-server) . 1.3.7.2. Disconnec ting fr om Within the R emot e Server S ession To disc onnec t a clien t from within the ser ver y ou must shut down the ser ver. 4029Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Operating in the F luen t Remot e Visualiza tion En vironmen tShut do wn the ser ver b y selec ting Shut down S erver in the File ribbon tab . File → Applic ations → Server → Shut down You c an also shut down the ser ver b y ent ering theserver/shutdown-server text command in the console . 1.4. Python, Scr ipting and Transcr ipts in the Remot e Clien t This sec tion is split in to the f ollowing par ts: 1.4.1. Python Scr ipting 1.4.2. Starting and S topping a Transcr ipt 1.4.1. Python Scr ipting Python c ommands allo w you t o quer y and/or mo dify some of the solution settings in the r emot e session, create new gr aphics objec ts, and so on. You c an also e xecut e commands t o initializ e the solution or c alcula te in the c onnec ted F luen t session. A P ython scr ipt allo ws you t o acc omplish these same op erations b y loading a scr ipt a t star tup or thr ough the ReadScriptFile command (as sho wn in Python Scr ipting (p.4030 ). There a multiple w ays tha t you c an load a P ython scr ipt in to the R emot e Visualiza tion C lient: •At star tup, using the -R command line option: flremote -R •Through the File menu: File → Read Scr ipt F ile... •Through the r emot e clien t console: ReadScriptFile(ScriptFile = "filename") The c onsole in the R emot e Visualiza tion C lient can b e used as a P ython 2.7 in terpreter.You c an imp ort any standar d Python mo dule and install new mo dules . Your mo del in F luen t is st ored in a hier archy of M odel S tate Objec ts. Model S tate Objec ts pr ovide func tionalit y to acc ess or mo dify pr oblem settings . The t ypes of M odel S tate Objec ts: •Paramet er—lo west le vel objec t, which is used f or st oring str ings , integers , doubles , and so on. •Singlet on—container objec t tha t holds a set of child M odel S tate Objec ts (which c an b e of an y type). •Named O bjec t—container objec t tha t holds a set of child M odel S tate Objec ts and is used when man y objec ts of the same t ype can e xist a t a par ticular le vel. For e xample , the t op-le vel RemoteSession objec t. An instanc e of RemoteSession exists f or e very remot e session tha t is cr eated. A RemoteSession objec t is pr e-popula ted in the P ython c onsole . Settings f or a sp ecific session c an be acc essed via the RemoteSession[""] objec t. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4030Remot e Visualiza tion and A ccessing F luen t Remot elyAction Metho d Gets the child names of obj obj.getChild- Names() For a S inglet on objec t, it retur ns the child M odel S tate objec t named "child". obj.child For a N amed O bjec t, it retur ns the M odel S tate child objec t with a displa y name or in ternal name of "name".obj["name"] For a N amed O bjec t, if a child with the name "name" do es not e xist, create it. Set the child objec t sta te to stat e.obj["name"] = state Iterator in terface: Allows you t o lo op thr ough the N amed O bjec t childr en of obj and do some ac tion on the childr en.for child in obj: do_some- thing(child) Check if childN ame is a N amed O bjec t child of obj . if childName in obj: do_something Delete the N amed O bjec t with name "name". del obj["name"] State Access and M odific ation Retur n the cur rent sta te of the objec t. For c ontainer objec ts, a P ython dictionar y is r etur ned .obj.getState() Set the cur rent sta te of the objec t. For c ontainer objec ts, state will b e a Python dic tionar y with the k eys corresponding t o the child objec t names .obj.set- State(state) Same as obj.getS tate(). obj() Same as par entO bj.obj .setS tate(stat e). parentO- bj.obj=state Retur n the in ternal name of the objec t. obj.name() Retur n the user-sp ecified name of the objec t. obj.displayName() Commands Get a list of a vailable c ommands tha t can b e execut ed on the objec t. obj.getCommands() Execut e the c ommand "c ommand" with the sp ecified ar gumen ts obj.command (arg1 = value1, arg2 = value2, ... ) Print a basic help ab out ar gumen ts for the sp ecified c ommand . If ther e ar e no ar gumen ts, nothing is pr inted.obj.command. help() Imp ortant Python c ommands tha t mo dify the F luen t applic ation should b e read fr om a scr ipt file using the File/Read Scr ipt F ile... menu option. This allo ws for each c ommand t o complet e before the ne xt command is e xecut ed.This is esp ecially imp ortant for in terdep enden t commands . Typing or pasting a ser ies of P ython c ommands dir ectly int o the R emot e Client c onsole c ould result in undesir able b eha vior as ther e is no w aiting f or the pr evious c ommand t o complet e before the ne xt command is e xecut ed. Note •Only a small subset of F luen t settings or ac tions ar e exposed in the scr ipting la yer. 4031Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Python, Scripting and Transcr ipts in the R emot e Client•While a scr ipt is e xecuting , func tions lik e Calculate() will w ait for the c ommand t o complet e (wher eas the c alcula tion is done in the back ground if the same c ommand is en tered b y typing in the c onsole). Sample Script The f ollowing e xample is a simple scr ipt tha t connec ts to session 1, reads a c ase (elb ow) in to the server, initializ es, mo difies the under-r elaxa tion fac tor for pr essur e, specifies the numb er of it erations , then b egins c alcula ting . Onc e the c alcula tion is c omplet e, it cr eates and displa ys a pr essur e contour plot of the r esults . session1 = RemoteSession['RemoteSession-1'] session1.ConnectionInfo.ServerInfoFilename = "server_info.txt" session1.Connect() session1.SendCommand(CommandName = "/file/read-case elbow.cas.gz") session1.Case.Solution.Calculation.Initialize() session1.Case.Solution.Controls.UnderRelaxationFactors['Pressure'].Value = 0.4 session1.Case.Solution.Calculation.NumberOfIterations = 20 session1.Case.Solution.Calculation.Calculate() session1.Case.Results.Graphics.createChild("Contour", "contour-1") session1.Case.Results.Graphics.Contour['contour-1'].Field = "pressure" session1.Case.Results.Graphics.Contour['contour-1'].Surfaces = ['inlet1', 'inlet2', 'outlet', 'wall'] session1.Case.Results.Graphics.Contour['contour-1'].Display() Refer to the P ython 2.7 do cumentation t o learn mor e ab out w orking with P ython. 1.4.2. Starting and S topping a Transcr ipt The tr anscr ipt f eature allo ws you t o sa ve the output of the main R emot e Visualiza tion c onsole in to a file, which includes the op erations tha t you p erform thr ough the GUI. You c an star t and st op r ecording a tr anscr ipt thr ough the File menu: File → Start Transcr ipt... File → Stop Transcr ipt Or y ou c an use the f ollowing P ython c ommands en tered in to the r emot e session c onsole t o acc omplish the same: •StartTranscript(TranscriptFile = "filename") •StopTranscript() 1.5. Remot e Visualiza tion B est P ractices This sec tion is a c ompila tion of b est pr actices for remot e visualiza tion. •The r emot e clien t immedia tely f etches da ta fr om a r unning (not solving) F luen t ser ver session. However, when the solv er is r unning the clien t cannot f etch da ta immedia tely.The r emot e clien t can only c ommunic ate with the solving F luen t ser ver when the cur rent iteration is o ver. For e xample , if an it eration tak es 5 sec onds , then the r emot e clien t will tak e at least 5 sec onds t o fetch the da ta af ter you mak e the r equest. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4032Remot e Visualiza tion and A ccessing F luen t Remot ely•While a r emot e clien t can c onnec t to multiple F luen t ser ver sessions , for b est p erformanc e you should tr y to ha ve the c onnec ted ser ver machines b e running simula tions tha t tak e a similar amoun t of time f or calcu- lating . •If a machine has multiple IP addr esses , you should set the REMOTING_SERVER_ADDRESS to an out ward facing IP addr ess, both on the clien t and ser ver machines so tha t the y can c ommunic ate with each other . •By default , both the r emot e clien t and F luen t ser ver session ha ve a 3 minut e timer f or completing a c ommu- nication b etween the t wo machines . If the c ommunic ation is not c omplet ed within the 3 minut es, then the remot e clien t and the F luen t ser ver will disc onnec t from each other .You c an r econnec t the session. If the communic ation timeout p ersists , you c an c ontrol the timeout b y setting the REMOTING_CONNEC- TION_TIME_OUT environmen t variable . •For b etter p erformanc e, you should disc onnec t the R emot e Visualiza tion C lient from the F luen t ser ver session, if you ar e not ac tively monit oring the solution on the clien t. 1.6. Remot e Visualiza tion C lien t Environmen t Variables In certain cir cumstanc es y ou ma y ha ve to change c ertain settings tha t are controlled b y en vironmen t variables .Table 1.1: Remot e Visualiza tion C lient En vironmen t Variables (p.4033 ) lists all of the en vironmen t variables tha t are sp ecific t o the F luen t Remot e Visualiza tion C lient and their uses .You c an define the environmen t variables in the Environmen t tab of the F luen t Launcher . Table 1.1: Remot e Visualiza tion C lien t Environmen t Variables Input & U se Variable time in seconds REMOTING_CONNECTION_TIME_OUT It is used t o define the time out f or requests fr om clien t to ser ver and visa-v ersa. The default v alue is 180 seconds (3 minut es). If a r equest is not c omplet ed b y the ser ver within this time , then the clien t will sho w an er ror. / for e xample , E:/Testing/remoting/example_logREMOTING_LOG_FILE It is used t o define the lo g file pa th. If this v ariable is defined , then the clien t and ser ver will wr ite lo g files . size in bytes REMOTING_MAX_MESSAGE_SIZE It is used t o define the maximum message siz e tha t the clien t and ser ver can e xchange . /portspan= REMOTING_PORTS It is used t o define the p ort range . If this v ariable is defined , then the r emot e clien t will tr y to star t the server within the sp ecified p ort range . Public facing IP address REMOTING_SERVER_ADDRESS It is used t o define the ser ver's IP addr ess. If this variable is defined , the r emot e clien t will not iden tify the IP addr es; it will use the pr ovided addr ess inst ead. The addr ess will b e wr itten t o the lo g file .Define this environment v ariable if the machine has multiple IP 4033Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Remot e Visualiza tion C lient Environmen t VariablesInput & U se Variable addr esses or if the R emot e Client is unable t o resol ve the IP addr ess. 1.7. Limita tions •While a r emot e clien t can c onnec t to up t o 6 diff erent remot e Fluen t ser ver sessions a t onc e, a single ser ver can only ha ve one r emot e clien t connec ted a t a time . •You c annot r ename or delet e gr aphics objec ts fr om the r emot e clien t •(Windo ws only) S tarting the ser ver is not supp orted if ANSY S Fluen t is launched with either the -g or -gu options fr om the c ommand line . •If a c alcula tion is star ted on the ser ver-side , the b eginning and end of the tr anscr ipt will b e missing on the clien t-side . •For an y ac tions sen t from the R emot e Visualiza tion C lient to the ser ver (initializa tion, star ting c alcula tion, text commands using Send C ommand t o Server), text prompts ar e aut oma tically answ ered. For e xample , if the question is A report file alr ead y exists with this name in the curr ent dir ectory. Create a ne w report file? ANSY S Fluen t aut oma tically answ ers yes to this question and b egins c alcula ting . •Do not star t calcula tions fr om the Send C ommand ... option on the clien t side- the y must b e star ted using the GUI on the clien t. •Plot pr operties (tha t is, axis and cur ve pr operties) ar e not tr ansf erred t o the R emot e Visualiza tion C lient. Residuals ar e alw ays plott ed on a lo garithmic sc ale and other plots ar e on a standar d sc ale. •Report plots c annot b e created or edit ed fr om the R emot e Visualiza tion C lient. •(Linux only) I f a R emot e Visualiza tion C lient is star ted fr om a ser ver, the clien t will close when the ser ver tha t launched it is closed . •Custom mesh c olors c an only b e set in the ser ver, although the y can still b e displa yed in the clien t. •When r unning in par allel, mesh par titions c an only b e displa yed on the ser ver. If you ha ve a mesh objec t with Partitions enabled and y ou displa y tha t mesh objec t on the clien t, you will not see the mesh par titions due t o this limita tion. •Differences b etween gr aphics objec ts on the ser ver and the c onnec ted clien t will not app ear if the displa yed options ar e not a vailable on the clien t. For e xample , if y ou enable Partitions in a mesh objec t on the ser ver, it will not app ear as ha ving changed on the clien t. •Mesh motion pr eview will not up date aut oma tically on the clien t. Client mesh displa ys are only up dated when y ou click Displa y. •Symmetr y,Mirror P lanes , and Periodic Rep eats displa ys are not supp orted on the clien t. •User-defined c olor maps ar e not a vailable f or the clien t. Any objec ts on the ser ver using a user-defined color map will not displa y on the clien t. •Commands tha t mo dify the sta te of the ser ver (such as initializa tion), retrieve the la test solv er settings when the y are sen t to the ser ver using the Send C ommand t o Server dialo g box.This c ould r esult Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4034Remot e Visualiza tion and A ccessing F luen t Remot elyin, for e xample , the numb er of sp ecified it erations on the clien t changing t o ma tch the numb er of iterations sp ecified on the ser ver. •Addon mo dules ar e not supp orted with the r emot e clien t. If you ha ve an addon mo dule enabled on the ser ver, information r egar ding the addon mo dule will not b e sho wn on the clien t. For e xample , Adjoin t residuals will not displa y on the clien t. •The clien t cannot displa y mor e than 20 windo ws. If you ha ve mor e items t o plot than 20, consider including multiple r eport definitions within a single r eport plot t o reduc e the numb er of windo ws. You c an also deac tivate report plots t o allo w for new plots without deleting the e xisting plots . •To reset the gr aphics windo w la yout in the clien t you must delet e the .flremote.layout file from the op erating sy stem home dir ectory, then close and r eop en the r emot e clien t. •Zoom-t o-fit do es not w ork on the r emot e clien t when the ser ver is it erating .You c an pause the c al- cula tion t o use the z oom-t o-fit func tionalit y. •If the Rep orting In terval in the Run C alcula tion task page is set t o a v alue gr eater than 1, residuals plott ed on the r emot e clien t will r espect tha t reporting in terval and will ther efore not app ear pr ecisely the same as the r esiduals plott ed on the ser ver. •Using a vir tual pr ivate net work (VPN) f or remot e visualiza tion ma y not w ork in some situa tions due t o certain firewall secur ity measur es in plac e at the ser ver sit e. Any disr uption in the VPN and/or in ternet c onnec tion may cause an une xpected failur e. •The viewing and displa y options a vailable in the r emot e clien t are based off of the dimensions of the most r ecently c onnec ted r emot e session. For e xample , assume y our r emot e clien t is c onnec ted t o two ser vers, one 3D and one 2D , and the 2D session w as c onnec ted sec ond .The a vailable displa y options in the clien t will r eflec t the a vailable options f or the 2D session, even if y ou ar e trying t o visualiz e on the 3D session. To remed y this issue , you c an disc onnec t and r econnec t the 3D session, which will mak e all of the 3D-r elated displa y options a vailable in the clien t. 4035Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Limita tionsRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4036Chapt er 2: Fluen t Icing The f ollowing sec tions of this chapt er ar e: 2.1. Overview of F luen t Icing 2.2. Quick S tart 2.3. Launching F luen t Icing 2.4. Fluen t Icing G raphic al User In terface La yout 2.5. Creating a F luen t Icing S imula tion 2.6. Setting-U p a F luen t Icing S imula tion 2.1. Overview of F luen t Icing This do cumen t provides some basic guidelines on ho w to simula te in-fligh t icing c onditions using F luen t Icing . Fluen t Icing unifies CFD simula tion of air flo w with in-fligh t icing ph ysics in a single-windo w, in- tegrated w orkflow. Fluen t Icing inc orporates the thr ee pr incipal asp ects of in-fligh t icing simula tions , airflow, par ticles (droplet and ic e cr ystal impingemen t limits and shado w zones), and ic e accr etion. It has no geometr ic limita tions and is applic able t o air craft, UAVs, nac elles , probes, det ectors, etc. Imp ortant The cur rent version of F luen t Icing e xposes only a subset of the full in-fligh t icing c apabilities and mo dules of FENSAP-ICE . In this v ersion, the FENSAP-ICE mo dules e xposed ar e, FENSAP for air flow (as an alt ernative to Fluen t), DROP3D f or par ticles and ICE3D f or ic e. More complet e information r egar ding these mo dules c an b e found in the FENSAP-ICE online do cumen tation. The f ollowing t ypes of icing analy sis c an b e performed with the cur rent release of F luen t Icing •Particles –Standar d dr oplets , SLD (br eak-up , splashing and b ouncing) and cr ystals –Transp ort of v apor –Appendic es C, O and D icing en vironmen ts –Predefined dr oplet siz e distr ibutions Langmuir A (M ono disp ersed) t o E •Ice –Rime, glaz e and mix ed icing c alcula tions –Single & multiple quasi-st eady shots c alled multishots 4037Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.–Automa tic mesh def ormation dur ing multishot c alcula tions 2.2. Quick S tart Note A complet e work pr ocedur e, with e xample da tasets and c onditions is a vailable under F luen t Icing in the F luen t Tutorial G uide . To set-up a c ase f or icing •Open the F luen t Icing applic ation. In Windo ws, go t o the Start menu and selec t Fluen t Applic ations → Icing . In Linux, launch icing from the fluent/bin directory. •Go to File → Open C ase... and selec t a suitable c ase (.cas ,.cas.gz ,.cas.h5 ) file , provided with a F luen t airflow converged solution alongside it (.da t,.dat.gz ,.dat.h5 ). Note The c ase must c ontain a 3D mesh without p olyhedr al or adapt ed elemen ts.The r eference conditions and ma terial t ype (A ir) should b e suitable f or icing c onditions . •When pr ompt ed t o Launch F luen t, selec t Yes. Fluen t is launched with the default numb er of CPU s (4) set in Preferenc es. •Onc e Fluen t is c onnec ted, use the icing applic ation t o review the c onditions and solv er settings: –Set-up → Airflow Review the air flow conditions and c onfigur e them if nec essar y. –Set-up→ Particles → Droplets Set the c onditions and default settings , which will b e used f or the par ticles simula tion. –Set-up → Ice Set the c onditions and default settings , which will b e used f or the ic e simula tion. –Set-up → Boundar y Conditions → wall-5 ,wall-6 wall-7 ,wall-8 Set temp erature to Adiaba tic + 10 by right-click ing the ic on of the w alls subjec t to icing . Double- click on each w all and ac tivate High r oughness f or Icing in Wall Roughness within the Properties windo w. •In Outline View → Solve: –The Airflow node is sho wn with a gr een check mar k, indic ating tha t an air flow solution w as loaded and is ready to use . –In the Solve → Particles node, the numb er of it erations f or the Particles solv er can b e configur ed. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4038Fluen t Icing→Right-click on Particles , and cho ose Calcula te. →The Particles solv er runs and pr oduces a dr oplet solution. –Use the r ibbon and click on View → Contour → Collec tion efficienc y – w alls option t o view the w ater catch on the w alls, the solution is displa yed in the G raphics windo w. –In the Solve → Ice node, the t otal time of ic e accr etion c an b e configur ed. →Right-click on Ice, and cho ose Calcula te. →The Ice solv er runs and pr oduces an ic e solution, which is c omp osed of sc alar v alues on w alls and the ice shap e. –Use the r ibbon and click on View → Ice cover options t o view the sc alars of the ic e solution as w ell as the ic e shap e using CFD-P ost or Viewmer ical. 2.3. Launching F luen t Icing The F luen t Icing applic ation c an b e star ted fr om either : •Your ANSY S installa tion f older –Windo ws fluent/bin/icing.bat in F luen t folder . –Linux fluent/bin/icing in the F luen t folder . •Your ANSY S Start menu in Windo ws Fluids → Fluen t Applic ations → Icing in the ANSY S Start menu en try. •An existing F luen t session, wher e an air flow case is loaded and r eady to simula te ice accr etion. You c an either launch F luen t Icing using the same machine as y our F luen t session or another machine . –To launch F luen t Icing fr om the same machine File → Applic ations → Icing This will op en the F luen t Icing windo w and will r un F luen t Icing on the same machine as y our F luen t session. –To launch F luen t Icing on a diff erent machine File → Applic ations → Server → Start. Selec t Icing in the p op-up windo w and sa ve a ser ver-inf o file. Start Fluen t Icing (on an y other machine), then use File → Connec t to... to connec t to the running F luen t ser ver, by using the ser ver inf o file . Note Network limita tions or fir ewall migh t aff ect the abilit y to connec t from a r emot e machine . 4039Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Launching F luen t IcingIf the F luen t Icing applic ation w as loaded first , closing the F luen t Icing applic ation will automa tically close its c onnec ted F luen t session. If Fluen t Icing w as star ted fr om F luen t itself , or c onnec ted via the Connec t to… menu , closing the Icing applic ation will not close Fluen t aut oma tically. 2.4. Fluen t Icing G raphic al U ser In terface Layout Figur e 2.1: The F luen t Icing G raphic al U ser In terface The F luen t Icing gr aphic al user in terface (Figur e 2.1: The F luen t Icing G raphic al U ser In terface (p.4040 )) consists of the f ollowing c omp onen ts •File (Top-L eft) Consists of file managemen t commands ( Open C ase,Save, etc.) •Ribbon (Top) Provides acc ess t o –Set-up →Some file managemen t commands Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4040Fluen t Icing→Special icing c onditions settings –View →Post-pr ocessing c ommands and quick-view ac tions •Outline View (Left) Contains a list of cur rently op en c ases . Each c ase is c onnec ted t o a F luen t session and pr ovides acc ess to –Set-up Model and c onditions settings f or each mo dule of the icing sequenc e –Solve Execution c ontrols of the solv ers –Results Post-pr ocessing da ta •Properties windo w (Center) Contains the settings of a selec ted it em in the Outline View. •Graphic windo ws (Right) Displa ys mesh, numer ical, postpr ocessed and monit oring da ta. •Console windo w (Bottom) Displa ys the pr ogress of y our simula tion and allo ws scr ipting of c ommands .The default c onsole is a Python c onsole . Note In the c ase of F luen t sessions , each session has a separ ate console windo w, which displa ys the fluen t execution lo g.This c onsole c annot b e used f or c ommands .To send a t ext command t o Fluen t, right-click on the F luen t case in the Outline View and cho ose Send Command ... File M enu •Open C ase 4041Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Fluen t Icing G raphic al User In terface La youtSelec t a c ase file and op en this c ase in a F luen t session, see Loading a C ase F ile (p.4044 ) •Connec t to... Connec t to an e xisting F luen t session, see Launching F luen t Icing (p.4039 ) •Save Case Save cur rent case file a t its cur rent location •Save All Save case file and all solution files alongside it •Save Case as ... Save case file and all solutions in a new lo cation or with a new file name •Imp ort Selec t a c ase file or gr id, and c opy it t o the cur rent work dir ectory, then op en F luen t. •Export –Write FENSAP gr id... Writes the cur rent case file t o a FENSAP-ICE gr id file f ormat •Read Scr ipt F ile... Selec t a p ython scr ipt file t o execut e, see Python C ommands (p.4099 ) •Preferenc es... Opens the F luen t preference windo w.The Icing windo w is sp ecific t o the Icing A pplic ation. See Preferences (p.4094 ). •Exit Exit the Icing applic ation All Fluen t sessions will also b e termina ted unless the session w as cr eated via a Connec t command , or the Icing applic ation w as launched fr om F luen t itself ) Ribbon C ommands •Set-U p Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4042Fluen t Icing–Case →Open... Selec t a c ase file and op en this c ase in a F luen t session, see Loading a C ase F ile (p.4044 ) →Imp ort... Selec t a c ase file or gr id, and c opy it t o the cur rent work dir ectory, then op en F luen t. →Save Save cur rent case file a t its cur rent location →Save all Save case file and all solution files alongside it →Save as… Save case file and all solutions in a new lo cation or with a new file name →Check Check the c ase and set-up f or c ompa tibilit y with Icing solv ers. See Case F ile R equir emen ts (p.4044 ) –Conditions →Atmospher ic Opens cloud en vironmen t types to define dr oplets and cr ystals pr operties. See Particles (p.4055 ). →Distribution Displa ys and t oggles b etween a vailable built-in par ticle distr ibutions . See Particles (p.4058 ) •View –Quick-vie w Access t o post-pr ocessing shor tcuts , see Quick-V iew (p.4090 ). –Graphics Create new p ost-pr ocessing objec ts. See B asic G raphics G ener ation within the F luen t User's G uide . 4043Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Fluen t Icing G raphic al User In terface La yout2.5. Creating a F luen t Icing S imula tion Fluen t Icing is mainly f ocused on c omputing par ticles and ic e simula tions fr om an air flow simula tion case file .Therefore, it is str ongly r ecommended t o set-up y our Airflow case file in F luen t before launching F luen t Icing . If available , an air flow solution (.da t) can also b e loaded with the c ase file . Note To set-up a F luen t case file f or icing c alcula tions , please c onsult Recommenda tions t o Set up a F luen t Calcula tion . Similar t o the F luen t Remot e Client, it is p ossible t o add multiple c ases , connec ted t o lo cal or remot e Fluen t sessions . However, each loaded c ase r equir es a separ ate Fluen t license & CPU s 2.5.1. Case F ile Requir emen ts The F luen t mesh must r espect the f ollowing pr operties: •3D only 2D F luen t mo de is not supp orted. 2D geometr ies ar e supp orted via 3D meshes with symmetr y or periodic planes . •Grids with p olyhedr al elemen ts or adapt ed gr ids with hanging no des ar e not supp orted. •Grids must not ha ve deac tivated z ones . Boundar y condition t ypes c annot b e changed inside F luen t Icing , ther efore the y must b e pr operly set- up b efore the c ase file is loaded in to Fluen t Icing . 2.5.2. Loading a C ase F ile Upon star tup, the F luen t Icing applic ation has no c ase loaded and pr esen ts an empt y Simula tions windo w. The first st ep t o set-up a F luen t Icing simula tion is t o either op en or imp ort a c ase file . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4044Fluen t Icing2.5.2.1. Opening a C ase F ile Set-U p → Open... selec ts a F luen t case file (*.cas ,*.cas.gz , *.cas.h5 ).This op eration will prompt the user t o launch F luen t. Fluen t will b e launched in a sec ondar y windo w, onc e the c onnec ted case file is loaded . If a F luen t solution file ( *.dat ,*.dat.gz ,*.dat.h5 ) is alongside the c ase file , it will b e also loaded . •Yes Fluen t is launched on the cur rent machine , using the default options inside Preferenc es. Note The default MPI t ype, and 3d double-pr ecision solv ers ar e aut oma tically used . Fluen t is launched in a separ ate windo w, minimiz ed up on star t-up . On some Windo ws managers , the windo w migh t not minimiz e and F luen t will op en o ver the F luen t Icing windo w.You c an swit ch back t o the F luen t Icing windo w onc e the c ase file is loaded . •No Fluen t launch is dela yed; the F luen t launch settings c an b e fine-tuned in the Properties of C ase windo w. Fluen t can la ter b e launched using the Start Fluent command as sho wn b elow. 4045Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Creating a F luen t Icing S imula tionFluent L aunch S ettings The default v alues f or the launch settings ar e set in the Preferenc es windo w, see Preferences (p.4094 ). If the v alue is unsuitable f or the cur rent run, mo dify these v alues in the Properties of C ase windo w before launching F luen t. •Numb er of CPU s The amoun t of MPI CPU s used t o launch the F luen t and an y other F luen t Icing solv er. A suitable license is r equir ed. •Use F luen t launcher The F luen t launcher is displa yed on F luen t star t-up and the launch options and en vironmen t can be fully c onfigur ed (such as J ob scheduler , remot e launch options , environmen t variables , etc.). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4046Fluen t IcingBelow ar e the e xecution r equir emen ts inside Fluen t Launcher : –Dimension → 3D –Options → Double P recision This is str ongly r ecommended f or incr eased pr ecision of mesh c oordina tes. –Processing Options → Parallel Serial is a depr ecated f eature not supp orted b y the F luen t Icing P articles and Ic e comp onen ts. 1 CPU c an also b e used in Parallel mo de. Note ACT and GPGPU s are not used b y FENSAP-ICE , ther efore not supp orted b y Fluen t Icing . Only 3D meshes ar e supp orted. 2.5.2.2. Imp orting a C ase F ile Fluen t Icing allo ws you t o imp ort (copy) case and mesh files t o your Working dir ectory. Imp ort Case – F luent C ase or Mesh Using the Import case command , a Fluen t case file (.cas ,.cas.gz ,.cas.h5 ) or mesh file (.msh ) can b e selec ted. If an air flow solution ( .dat ) file e xists in the same lo cation with the same root name as y our c ase file , it will also b e copied t o your w orking dir ectory. If the file is a .msh mesh file, it will b e copied as a .cas file. Note Fluen t Icing do es not off er the option t o mo dify the b oundar y condition t ype.The boundar y conditions t ypes need t o be set-up b eforehand in F luen t. Imp ort Case - FENSAP Using the Import case command , a FENSAP f ormat grid (*.grid ) file c an b e selec ted.When imp orted, the gr id file is c onverted t o Fluen t case file f ormat. Note All inlet sur faces ar e aut oma tically set-up as pr essur e-far-field . The air ma terial pr operties and the ener gy / visc ous mo dels ar e set t o the default r ecom- mended v alues , see Recommended S ettings (p.4053 ). Working dir ectory A w orking dir ectory is an optional dir ectory which c an b e used t o store the c ase files cur rently w orked upon. If enabled , this dir ectory will b e used t o imp ort cases and used as the default curr ent directory for F luen t Icing c alcula tions . 4047Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Creating a F luen t Icing S imula tionThe w orking dir ectory can b e enabled and c onfigur ed thr ough the Preferenc es windo w under the Icing categor y. 2.6. Setting-U p a F luen t Icing S imula tion Onc e a c ase file is loaded , a simula tion tr ee app ears under y our c ase file .This tr ee if c omp osed of thr ee main c omp onen ts Set-up ,Solve and Results . Set-up Defines the t ype of simula tion, the in-fligh t icing c onditions , the ph ysical mo dels and the b oundar y conditions t o use in y our simula tion. Solve Defines the solv er settings of y our in-fligh t icing simula tion including monit oring, initializa tion and output files . Results Allows post-pr ocessing of y our in-fligh t icing r esults . 2.6.1. Set-up Simulation Type To star t your simula tion, you must define its t ype.Three t ypes ar e pr ovided in the Properties of S et- up windo w of the Set-up comp onen t. •Airflow The air flow solv er.Two solv ers ar e supp orted (F luen t and FENSAP). •Particles The par ticles impingemen t solv er, in this c ase DR OP3D . An air flow solution is r equir ed b efore con- duc ting this simula tion. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4048Fluen t Icing•Ice The ic e accr etion solv er, in this c ase ICE3D . An air flow and par ticles solution ar e requir ed b efore conduc ting this simula tion. Therefore, five combina tions of simula tion t ypes ar e supp orted: •Stand-alone Airflow simula tion •Stand-alone Particles simula tion, with an air flow solution alr eady loaded . •Stand-alone Ice simula tion, an Airflow and Particles solution alr eady loaded . •An Airflow + Particles simula tion. Each simula tion is r un in sequenc e. •An Airflow + Particles + Ice simula tion. Each simula tion is r un in sequenc e.This c ombina tion allo ws the simula tion of single and multiple quasi-st eady (multishot) ic e accr etion c alcula tions . Disabling a Simula tion t ype from the Properties of S et-up windo w of Set-up will hide its r elevant settings fr om the Outline View. Example 2.1: Some S ettings A re Used b y All Simula tion Types and Will B e D ispla yed a t All Times Airflow conditions ar e used b y all 3 simula tion t ypes and Particle conditions ar e requir ed f or Ice. 4049Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting-U p a F luen t Icing S imula tionGlobal settings •Advanc ed f eatures Activates additional options within some F luen t Icing windo ws, see Advanced S ettings (p.4095 ). •Beta f eatures Activates F luen t Icing Beta f eatures. Consult the F luen t Beta F eatures M anual f or mor e inf ormation. 2.6.1.1. Airflow The Properties of A irflow windo w defines the air flow solv er, the air flow conditions and the dir ection of the icing simula tion. Gener al Choose b etween F luen t and FENSAP as the Airflow solv er.Your choic e will app ear in the Outline View as an Airflow branch under Set-up . Clicking on this br anch will allo w the set-up of the air properties and ph ysical mo dels of either F luen t or FENSAP . Conditions These ar e the r eference air flow conditions used b y all simula tion t ypes. By default , its v alues ar e copied fr om the Referenc e Conditions of the c ase file . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4050Fluen t Icing•Sync with F luen t ref. conditions If this option is enabled , any change in the Conditions windo w will b e mir rored t o the Referenc e Conditions windo w of the F luen t windo w. If this option is disabled , these v alues ar e used only inside F luen t Icing , and the Referenc e Conditions in the F luen t windo w will r emain unchanged . •The par amet ers sho wn b elow Sync with F luen t ref. conditions mainly c orrespond t o the r eference values descr ibed in FENSAP-F low Solution →Flow Conditions → Reference Conditions of the FENSAP-ICE U ser Manual. The table c onnec ts these v ariables t o FENSAP-ICE or F luen t variables . Fluen t FENSAP-ICE Fluen t Icing Length Characteristic length Characteristic L ength Velocity Air velocity Speed Temp erature Air sta tic t emp erature Temp erature Gauge P ressur e Air sta tic pr essur e (FENSAP only supp orts absolut e pr essur eRela tive Pressur e Operating P ressur e Operating P ressur e quan tities). The A ir sta tic pressur e of FENSAP is the sum of the R elative Pressur e and the Operating P ressur e in F luen t Icing .) Note If you w ould lik e to use absolut e pr essur es in F luen t Icing , set the Operating P ressur e to 0 Pa in the Properties of A irflow windo w.The Rela tive Pressur e and Gauge P ressur e becomes the sta tic pr essur e. Direction Two appr oaches t o sp ecify the or ientation of the r eference air flow is supp orted. •Cartesian c omp onen ts The dir ection is sp ecified b y assigning v elocity comp onen ts in X, Y and Z. Angle of a ttack The dir ection of the flo w is sp ecified via t wo angles ,AoA [deg .] and Yaw [deg .] and its v elocity magnitude b y Velocity magnitude [m/s] .The planes on which these t wo angles ar e defined ar e obtained b y selec ting the c oordina te axis of lif t (Lift Direction ) and dr ag ( Drag D irection ) for a z ero degr ee A oA.The A oA is defined on the plane c onsisting of the Drag D irection as the pr imar y axis and the Lift Direction as the sec ondar y axis , while the Yaw angle is defined on the plane c onsisting of the Drag D irection as the pr imar y axis and the r esult of the cr oss pr oduc t of Drag D irection x Lift Direction as the sec ondar y axis . For instanc e, if the Drag D irection is set t o X+ and the Lift Direction is set t o Y+, the flo w dir ection will b e defined b y the X+ axis if y ou set the AoA [deg .] and Yaw [deg .] to 0 degr ee. If the AoA [deg .] is set t o 90 degr ees and the Yaw [deg .] is set t o 0 degr ee, the flo w will b e en tirely in the Y+ direction. If the AoA [deg .] is set t o 0 degr ee and the Yaw [deg .] is set t o 90 degr ees, the flo w will b e en tirely in the Z+ direction. 4051Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting-U p a F luen t Icing S imula tionFluent A irflow S olver If Fluen t has b een selec ted as the A irflow solv er in the Properties of A irflow windo w, the f ollowing Properties of F luen t windo w app ears if y ou click on Set-up → Airflow → Fluen t. In this windo w, you c an sp ecify the ma terial pr operties of air and the most c ommon ph ysical mo dels of air used f or icing simula tions . For mor e inf ormation r egar ding r ecommenda tions on ho w to set-up air pr operties and ph ysical models in F luen t, consult Recommended S ettings (p.4053 ). Materials Set the same air pr operties as the ones c oming fr om the loaded c ase file ( Fluid set t o Case settings ) or set new air pr operties ( Fluid set t o Air). The par amet ers sho wn b elow Fluid are the F luen t par amet ers and the y only app ear if Fluid is set t o Air. Only Ideal gas and Constan t pr operties are supp orted b y Fluen t Icing . Follow Recommended Settings (p.4053 ) to define the air pr operties f or icing c alcula tions . Models The par amet ers sho wn in Models are the F luen t par amet ers under Setup → Models . Only the ph ys- ical mo dels r ecommended in sec tion R ecommenda tions t o Set up a F luen t Calcula tion of the FENSAP- ICE U ser M anual ar e pr ovided . Follow Recommended S ettings (p.4053 ) to selec t the appr opriate mo dels for icing c alcula tions . The Other flag is displa yed ne xt to Turbulenc e when the c ase file c ontains a visc ous mo del tha t is different than the ones supp orted b y Fluen t Icing ( k-Omega 2-eqn and Transition SST 4-eqn ). Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4052Fluen t IcingAlthough visc ous hea ting and ener gy app ear as options her e to be compa tible with standar d Fluen t setup , the y ha ve to be enabled f or icing simula tions other wise hea t transf er coefficien ts used in the ice accr etion mo del will not b e calcula ted c orrectly. Commands Access the f ollowing c ommands b y right-click ing on F luen t, located in Set-up → Airflow → Fluen t. •Set to default A ir pr operties Changes the cur rent ma terial t o Air and will set the air ma terial pr operties t o the Rec ommended settings , see Recommended S ettings (p.4053 ). •Set to default M odels Enable the Rec ommended settings for mo dels . See Recommended S ettings (p.4053 ). •Update with F luen t settings Use this option t o synchr oniz e your F luen t session changes with F luen t Icing . Note Changes made t o Fluen t Icing ar e aut oma tically synchr oniz ed with F luen t. Recommended S ettings When p erforming icing simula tions using F luen t as the air flow solv er, the f ollowing Material settings for Air are recommended . •Set the Densit y - Option to ideal-gas •Set the Cp - Option to 1004.688 J/kg/K. This v alue is equal t o 7/2, the gas c onstan t R of 287.05376 J/kg/K. •Set the Thermal C onduc tivit y - Option to Constan t and set its Constan t to an appr opriate value f or the condition. To comput e its v alue , refer to the ther mal c onduc tivit y equa tion b elow. 4053Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting-U p a F luen t Icing S imula tion•Set the Dynamic Visc osit y - Option to Constan t, and set its Constan t to an appr opriate value f or the condition. To comput e its v alue , refer to the visc osity equa tion b elow. Use the f ollowing equa tions t o comput e the ther mal c onduc tivit y and d ynamic visc osity, respectively. Further mor e, the f ollowing Model settings ar e recommended . –Energy must b e enabled f or icing simula tions . –The Turbulenc e mo del K-Omega 2-eqn is recommended f or icing simula tions . –Visc ous H eating and Turbulenc e Produc tion Limit er must b e enabled f or icing simula tions . FENSAP A irflow S olver If FENSAP has b een selec ted as the Airflow solv er in the Properties of A irflow windo w, the f ollowing Properties of FENSAP windo w app ears if y ou click on Set-up → Airflow → Fensap . In this new windo w, you c an sp ecify the most c ommon ph ysical mo dels of air and options f or ar tificial visc osity used in icing simula tions . The most c ommon air flow pr operties of FENSAP f or icing simula tions ar e the Ideal G as pr operties with c onstan t ther mal c onduc tivit y and d ynamic visc osity as sp ecified in the Recommended S et- tings (p.4053 ). Model In Fluen t Icing , the M omen tum equa tions ar e alw ays set t o Navier-S tokes and thr ee options ar e available f or Energy. Full PDE ,Constan t en thalp y and Energy only .Full PDE is the most c ommon option f or icing applic- ations . By default , FENSAP solv es the ener gy equa tion in non-c onser vative form which r esults in r obust convergenc e esp ecially when the momen tum and ener gy sy stems ar e unc oupled .To solv e the ener gy equa tion in c onser vative form, enable Conser vative. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4054Fluen t IcingFor mor e inf ormation r egar ding these settings , consult The Ener gy Equa tion . Turbulenc e All turbulenc e and tr ansition mo dels of FENSAP ar e supp orted in F luen t Icing .The default settings (SA with no tr ansition) ar e the most c ommon f or ic e accr etion simula tions . For mor e inf ormation r e- garding these mo dels , consult sec tion Turbulen t Flows and Transition t o Turbulenc e. Note Default numer ical convergenc e settings ar e applied t o all turbulenc e mo dels of FENSAP . Artificial Visc osit y All the ar tificial visc osity options of FENSAP ar e supp orted in F luen t Icing .The default settings (Streamline up wind with sec ond or der cr oss-wind dissipa tion of 1e-7) ar e the most c ommon settings to obtain an accur ate and stable air flow solution with FENSAP .To impr ove the accur acy, you c an r educ e the cr oss-wind dissipa tion as long as y ou ar e able t o main tain a stable solution and a smo oth distr i- bution of shear str esses and c onvective hea t flux es o ver the w alls of y our geometr ic mo del. For mor e information r egar ding these ar tificial visc osity mo dels , consult Artificial D issipa tion . 2.6.1.2. Particles The Properties of P articles windo w defines the t ype of par ticles t o simula te and the ac tivation of the ener gy equa tion in the e vent tha t high t emp erature gr adien ts migh t aff ect the lo cal concentration of these par ticles within the c omputa tional domain. Note The air and par ticles c ould b e solv ed simultaneously (as a t wo-phase flo w). However, sinc e the par ticles v olume fr action is v ery small, the t wo-phase flo w is c onsider ed a dilut e gas- particle flo w and thus the go verning equa tions of air and par ticles ar e solv ed in a segr egated manner .The air flow is solv ed first , followed b y the par ticle equa tions . In this manner , the effect of the air on the par ticles is c onsider ed, but not the r everse . Type Three par ticle t ypes ar e supp orted: •Droplets 4055Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting-U p a F luen t Icing S imula tionSup ercooled w ater dr oplets tha t are still in liquid f orm a t lower ambien t temp eratures.They typic ally accr ete on e xternal air craft sur faces. •Crystals Ice cr ystals ar e solid ic e par ticles of v arious siz es tha t are susp ended in air .They typic ally accr ete on in ternal air craft sur faces wher e lar ge t emp erature gr adien ts ar e experienc ed. •Vapor Water v apor is a substanc e in the gas phase . In icing mo deling , its c oncentration c an v ary by mass and ener gy transf er with dr oplets/cr ystals . These par ticle t ypes c an b e selec ted c oncur rently and thus the y can all b e simula ted simultaneously within the same Particle simula tion. Enabling a par ticle Type from the Properties of P articles windo w will cr eate its c orresponding br anch under P articles as w ell as an y other r elevant setting r elated t o this par ticle t ype in Boundar y Condi- tions and Solve. Model By default , continuit y and momen tum equa tions of dr oplets and cr ystals , and c ontinuit y equa tions of v apor ar e alw ays solv ed when these par ticles ar e selec ted in Type.These ar e the t ypic al equa tions needed t o stud y external in-fligh t icing ph ysics. For mor e inf ormation r egar ding these equa tions , consult The P article Transp ort and Sup ercooled Lar ge D roplets (SLD) . To ac tivate the ener gy transf er b etween par ticles as w ell as their r espective phase change , the Particle ther mal equa tion must b e enabled . It is r ecommended t o enable this option when stud ying in ternal in-fligh t icing ph ysics, e.g. inside engines . Droplets If Droplets has b een selec ted as a par ticle Type in the Properties of P articles windo w, the f ollowing Properties of D roplets windo w app ears when y ou click on Set-up → Particles → Droplets . In this windo w, you c an sp ecify the ambien t/reference conditions of w ater dr oplets , the t ype and siz e distr i- bution, and the dr ag mo del. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4056Fluen t IcingDroplet c onditions The main ph ysical par amet ers descr ibing the dr oplets ar e: •LWC [k g/m3] •The Liquid Water C ontent (LWC) is the c oncentration of w ater dr oplets in the air . •Droplet diamet er [micr ons] Spher ical dr oplets ar e assumed t o be of a single , unif orm siz e, usually equal t o the median v olume diamet er (MVD) of the sample siz e distr ibution. In Particles , the dr oplet diamet er is the MVD . •Water densit y [k g/m3] This is the densit y of the w ater dr oplets . By default , its v alue is set t o 1,000 k g/m3. •SLD Sup ercooled Lar ge D roplets (SLD) options allo w the set-up of e xtra ph ysical mo dels when w ater droplets e xceed a MVD of ~40 micr ons. •Appendix c onditions Allows to set-up r ecogniz ed cloud en vironmen t type conditions . In this c ase, droplet c onditions will b e aut oma tically defined based on fligh t conditions and dr oplet siz e.The f ollowing app endic es are supp orted –Appendix C In gener al, environmen t type for dr oplet siz es b elow 40 micr ons. –Appendix O In gener al, environmen t type for dr oplet siz es tha t exceed 40 micr ons. For mor e inf ormation r egar ding these app endic es, please c onsult Appendix C and Appendix O - Sup ercooled Lar ge D roplets . 4057Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting-U p a F luen t Icing S imula tionParticle distr ibution Only built-in dr oplet siz e distr ibutions ar e cur rently supp orted b y Fluen t Icing .These distr ibutions can b e selec ted in the Droplet distr ibution pull-do wn menu . •Mono disp erse Indic ates tha t a c alcula tion is p erformed using a single diamet er.This diamet er is sp ecified in the Droplet diamet er box and c orresponds t o the MVD . •Langmuir B t o E Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4058Fluen t IcingIf one of these is selec ted, water dr oplets ar e simula ted b y computing the dr oplet c oncentration and sp eed f or each individual diamet er of the discr ete distr ibution, which ar e subsequen tly aut o- matically w eigh t-averaged a t the end of the simula tion. Fluen t Icing alw ays uses 7 dr oplet diamet ers to represen t a Langmuir B t o E distr ibution. The v arious Langmuir diamet er distr ibutions and their corresponding w eigh ts ar e pr e-defined in FENSAP-ICE .To lear n mor e ab out these distr ibutions and their r espective weigh ts, please c onsult Droplets R eference Conditions . Model In this submenu , diff erent water dr oplet ph ysical mo dels c an b e enabled in or der t o incr ease the ac- curacy of y our w ater dr oplet simula tion. Some of these mo dels ar e only a vailable when the SLD option is enabled in Droplet c onditions . •Gener al M odels –Droplet dr ag mo del These mo dels c orrespond t o dr ag c orrelations . Only 4 choic es ar e available ( Water,Water -S tokes law,Water – e xtended Re ynolds ,Snowflak es).The default dr ag mo del is set t o Water, which is the dr ag mo del used in almost all our w ater dr oplet v alida tion c ases . For mor e inf ormation regar ding these mo dels , please c onsult Particle D rag C orrelations . •SLD only M odels –Break-up mo del Models the pr ocess b y which a lar ge dr oplet is br oken up in to smaller dr oplets due t o aer ody- namic f orces.To enable this mo del, selec t Pilch & E rdman , the only br eak mo del supp orted in FENSAP-ICE . If selec ted, an e xtra go verning equa tion is solv ed f or dr oplet diamet er. For mor e information r egar ding this mo del, please c onsult Droplet B reak-U p. –Splashing and b ouncing Only the By post-pr ocessing with thr ee splashing mo dels ( Mundo ,Honsek and Wright) are supp orted in F luen t Icing .These ar e the most v alida ted mo dels used in SLD splashing & b ouncing simula tions , with a pr eference for Mundo , default Splashing mo del setting .They mo dify the droplet c ollec tion efficienc y on the sur face by pr edic ting if w ater dr oplets b ounc e or splash. Droplets tha t bounc e or splash ar e not r e-in troduced in to the c omputa tional domain. For mor e information r egar ding these mo dels , consult Splashing and B ouncing b y Post-P rocessing ,Mundo Model,Honsek-Habashi M odel and the Wright Potap czuk M odel sec tion within the FENSAP-ICE User M anual. –Terminal Velocity This option enables SLD par ticles t o fall without e xceeding its t erminal v elocity (maximum fall speed). This option will alt er the tr ansp ort of dr oplets and ther efore its impingemen t.The dir ection 4059Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting-U p a F luen t Icing S imula tionand the magnitude of the gr avity vector must b e sp ecified in the c ase file . For mor e inf ormation regar ding this mo del, please c onsult Terminal Velocity. Crystals If Crystals has b een selec ted as a par ticle Type in the Properties of P articles windo w, the f ollowing Properties of C rystals windo w app ears when y ou click on Set-up → Particles → Crystals . In this windo w, you c an sp ecify the ambien t/reference conditions of cr ystals . Note Only one dr ag mo del of cr ystals has b een implemen ted and it f ollows the obla te spher oidal drag c orrelation f ormula ted b y Pitter. For mor e inf ormation r egar ding this mo del, please consult Ice Crystal D rag C orrelations . Crystal c onditions The main ph ysical par amet ers descr ibing the ic e cr ystals ar e: •Ice Crystal C ontent [kg/m3] The Ic e Crystal C ontent (IC C) is the c oncentration of cr ystals in the air . •Crystal diamet er [micr ons] Ice cr ystals ar e assumed t o be of a single , unif orm siz e. In this c ase, the cr ystal diamet er corresponds of the semi-major axis length of a thin obla te spher oid. •Crystal densit y [k g/m3] This is the densit y of the ic e tha t forms the ic e cr ystal. By default , its v alue is set t o 917 k g/m3. •Crystal A spect Ratio This is the asp ect ratio (E=b/a) of an obla te spher oid, wher e b is the semi-major axis length and a is the semi-minor axis length. •Appendix c onditions Allows to set-up the r ecogniz ed cloud en vironmen t type condition c alled Appendix D (cr ystals) . In this c ase, ice cr ystal c onditions will b e aut oma tically defined based on fligh t conditions , the Total Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4060Fluen t IcingWater C ontent (TWC = L WC + IC C) and the L WC, if dr oplets ar e pr esen t. For mor e inf ormation r e- garding A ppendix D , please c onsult Appendix D - Ic e Crystals . Vapor If Vapor has b een selec ted as a par ticle Type in the Properties of P articles windo w, the f ollowing Properties of Vapor windo w app ears when y ou click on Set-up → Particles → Vapor. In this windo w, you c an sp ecify the ambien t/reference conditions of v apor. Conditions The main ph ysical par amet ers descr ibing v apor ar e: 4061Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting-U p a F luen t Icing S imula tion•Rela tive Humidit y [%] This option is enabled if selec ted under Vapor initializa tion .This option c orresponds t o the ambien t relative humidit y and r anges fr om 0 t o 100 %. It is defined as the r atio of par tial v apor pr essur e to the sa turation v apor pr essur e. •Vapor C onc entration [k g/m3] This option is enabled if selec ted under Vapor initializa tion .This option c orresponds t o the ambien t vapor c oncentration. 2.6.1.3. Ice The Properties of Ic e windo w defines the icing c onditions and the icing ph ysical mo dels t o use during the ic e accr etion simula tion. Ice accr etion c onditions The main ph ysical par amet ers descr ibing the ic e accr etion pr ocess ar e: •Rec overy fac tor The r ecovery fac tor is used t o in troduce the eff ect of the ener gy losses due t o friction when c om- puting the adiaba tic/r ecovery temp erature at the w all.This is a fac tor tha t is used t o comput e the convective hea t transf er coefficien ts in FENSAP-ICE f or ambien t/reference or icing t emp eratures. Its default v alue is 0.9 (~P r1/3), a value tha t has b een used in se veral icing v alida tion c ases . •Icing air t emp erature [K] The icing air t emp erature is the sta tic t emp erature at which ic e accr etion is c omput ed.This t emp er- ature can thus b e diff erent than the ambien t air t emp erature sp ecified in the Properties of A irflow Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4062Fluen t Icingwindo w or inside y our inlet b oundar y conditions . If the ener gy equa tion of par ticles is enabled , the icing air t emp erature must b e the ambien t air t emp erature sp ecified in the Properties of A irflow. •Rela tive humidit y [%] This is the r elative humidit y expressed in p ercentage v alue . For clouds , this v alue should b e set t o 100%. If Vapor has b een enabled in Particles , this par amet er is disabled , and v apor distr ibutions are used inside the icing mo dels . For mor e inf ormation r egar ding these par amet ers, consult Icing C onditions . Model The main ph ysical mo dels descr ibing the ic e accr etion pr ocess ar e •Icing mo del The icing mo dels solv e the SWIM equa tions (see Governing E qua tions ) in diff erent forms. –Glaze Solves all the SWIM equa tions f or temp eratures b elow, at and ab ove freezing and thus is the most gener al mo del as it solv es for the 3 sta tes of w ater (liquid , solid and gas). It is the default model of the Ic e simula tion c omp onen t. –Water film Solves the SWIM equa tions f or temp eratures ab ove the fr eezing p oint.Thus, no dr oplets/cr ystals are expected t o contribut e to ice formation. This option is useful f or solving sur face water flo w problems . –Rime Solves the SWIM equa tions f or temp eratures w ell b elow the fr eezing p oint. In this c ase, all dr oplets are assumed t o freeze on impac t and thus no r unback is mo deled .The ener gy equa tion is not solv ed and the w all t emp erature remains a t the r ecovery temp erature. •Beading When enabled , the b eading mo del c alcula tes v ariable sur face roughness e volution on ic ed w alls. The r esultan t roughness is e xpressed as equiv alen t sand-gr ain r oughness . During a multishot sim- ulation this sand-gr ain r oughness aff ects the c onvective hea t flux es and thus the lo cal cooling eff ects over ic ed sur faces. Most imp ortantly, it elimina tes the guess w ork of cho osing an initial w all roughness which w ould b e applied t o the en tire wall unif ormly. It is ther efore recommended t o activate this mo del t o obtain accur ate multishot r esults . Crystals Bouncing app ears in the Properties of Ic e windo w if Crystals has b een selec ted in the Properties of P articles windo w.Bouncing enables the c ontribution of cr ystals t o the icing c alcula tion, other wise , Ice assumes tha t all cr ystals b ounc e off the sur face,No bouncing .Two bouncing mo dels ar e available . •NTI B ouncing M odel 4063Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting-U p a F luen t Icing S imula tionThis mo del det ermines the amoun t of cr ystals tha t stick based on lo cal sur face conditions , such as impac t velocity, crystal siz e and film heigh t.The mo del also includes an optional f eature to acc oun t for cr ystal Erosion effects on ic e accr eting sur faces. •NRC Bouncing M odel This mo del c alcula tes the stick ing fac tion based on the L WC t o TWC r atio hitting the sur face. Conditions •Ice densit y type Four w ays to sp ecify the ic e densit y (Constan t,Mack lin,Jones G laze and Jones R ime ) are supp orted in Fluen t Icing . By default , a constan t value of 917 k g/m3 is set. This v alue has b een used in man y ice shap e valida tion c ases and it is thus r ecommended t o use this option and this v alue .The other densit y types ar e correlations tha t uses the lo cal ic e sur face temp erature and other icing c onditions . For mor e inf ormation r egar ding these ic e densit y correlations , consult Ice Densit y. 2.6.2. Boundar y Conditions Partial diff erential equa tions ar e solv ed f or each F luen t Icing c omp onen t.Therefore, each c omp onen t requir es a set of suitable b oundar y conditions .The options sho wn in each b oundar y condition t ype reflec t the simula tion t ype, conditions and ph ysical mo dels selec ted/enabled in Airflow,Particles and Ice. Note Fluen t Icing do es not off er the option t o mo dify b oundar y condition t ypes and thus the y must b e set-up b eforehand in F luen t. Only a c ouple of F luen t boundar y condition t ypes ar e cur rently supp orted b y Fluen t Icing . •Inlet Type –Pressur e -far-field –Velocity Inlet –Mass-flo w Inlet –Pressur e Inlet •Walls •Outlet Type –Pressur e Outlet •Symmetr y •Periodic Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4064Fluen t IcingIn the ne xt sec tions , a br ief descr iption of the c ontent of Inlet , Outlet and Wall Types is pr ovided . Symmetr y and p eriodic t ypes do not r equir e a sp ecific set-up f or icing applic ations and ther efore ar e not descr ibe her e. 2.6.2.1. Inlet Types Ice accr etion simula tions r equir e inlet air flow and par ticles b oundar y conditions . Four t ypes of F luen t boundar y condition t ypes ar e supp orted t o simula te the A irflow comp onen t of F luen t Icing . Since the P articles c omp onen t only supp orts D irichlet b oundar y conditions , par ticle c oncentration and v e- locity conditions ar e sp ecified on all F luen t boundar y types. The f ollowing figur es sho w the P roperties of each Inlet b oundar y type supp orted b y Fluen t Icing when all par ticles t ype ar e enabled . 4065Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting-U p a F luen t Icing S imula tionAirflow To ease the set-up of the Airflow solv er, it is p ossible t o aut oma tically define the b oundar y conditions for all the Inlet t ypes b y selec ting one of the t wo options under Conditions . •Case settings With this option, inlet b oundar y conditions ar e aut oma tically tak en fr om y our c ase file .Therefore, this is only a vailable if a c ase file has b een setup b eforehand with F luen t. •Edit With this option, you c an define b oundar y conditions tha t are diff erent than those c ontained in the or iginal c ase file or in the Properties of A irflow settings . The f ollowing tables map the F luen t Icing air flow b oundar y conditions t o Fluen t and FENSAP air flow boundar y conditions when Edit is selec ted. Table 2.1: Pressur e Far-F ield , Mapping of A irflow F luen t Icing B oundar y Condition in to Fluen t & FENSAP B oundar y Conditions FENSAP Fluen t Fluen t Icing Type: Sup ersonic or Far-fieldType: Pressur e-far-fieldType: Pressur e-far-field Temp erature Temp erature (k) Temp erature [K] Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4066Fluen t IcingFENSAP Fluen t Fluen t Icing Pressur e Gauge P ressur e (pasc al)Gauge P ressur e [P a] Velocity mo de --------- --------- Speed [m/s] --------- Mach numb er Mach numb er --------- Direction mo de --------- Vector Comp onen ts Velocity X X-Comp onen t of Flow D irectionFlow dir ection X Velocity Y Y-Comp onen t of Flow D irectionFlow dir ection Y Velocity Z Z-Comp onen t of Flow D irectionFlow dir ection Z Vector A ngle --------- --------- Alpha (X-Y ) [deg] --------- --------- Beta (X-Z) [deg] Table 2.2: Velocity Inlet , Mapping of A irflow F luen t Icing B oundar y Condition in to Fluen t & FENSAP B oundar y Conditions FENSAP Fluen t Fluen t Icing Type: SubsonicType:Velocity Inlet Type:Velocity Inlet Temp erature Temp erature (k) Temp erature [K] --------- Sup ersonic / Initial G auge P ressur e (pasc al)Gauge P ressur e [P a] Velocity Mode --------- Velocity Magnitude (m/s) Speed [m/s] --------- --------- Mach numb er --------- Magnitude , Normal t o Boundar y Normal t o the b oundar y Direction Vector C omp onen ts Velocity X X-C omp onent of F low D irection Flow dir ection X Velocity Y Y-Comp onent of F low D irection Flow dir ection Y Velocity Z Z-C omp onent of F low D irection Flow dir ection Z Vector A ngle 4067Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting-U p a F luen t Icing S imula tionFENSAP Fluen t Fluen t Icing --------- --------- Alpha (X-Y ) [deg] --------- --------- Beta (X-Z) [deg] Table 2.3: Mass F low Inlet , Mapping of A irflow F luen t Icing B oundar y Condition in to Fluen t & FENSAP B oundar y Conditions FENSAP Fluen t Fluen t Icing Type: Mass F low Type: Mass F low Inlet Type: Mass F low Inlet Static Temp eratureTotal Temp eratur e (k) Temp erature [K] -------- Sup ersonic / Initial G auge P ressur e (pasc al)Gauge P ressur e [P a] -------- --------- Direction mo de Direction Vector Mass F low Mass F low R ate (kg/s) Mass F low [kg/s] Alpha & B eta X-Comp onen t of F low D irection Flow dir ection X Y-Comp onen t of F low D irection Flow dir ection Y Z-Comp onen t of F low D irection Flow dir ection Z Normal t o Boundar y -------- Mass F low R ate (kg/s) Mass F low [kg/s] Table 2.4: Pressur e Inlet , Mapping of A irflow F luen t Icing B oundar y Condition In to Fluen t Boundar y Conditions Fluen t Fluen t Icing Type: Pressur e Inlet Type: Pressur e Inlet Total Temp eratur e (k) Temp erature [K] Sup ersonic / Initial G auge P ressur e (pasc al) Gauge P ressur e [P a] Normal t o Boundar y Normal t o the b oundar y X-Comp onen t of F low D irection Flow dir ection X Y-Comp onen t of F low D irection Flow dir ection Y Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4068Fluen t IcingFluen t Fluen t Icing Z-Comp onen t of F low D irection Flow dir ection Z Note Velocity M ode allo ws the use of Speed [m/s] or Mach numb er as a b oundar y condition when the Inlet is a P ressur e Far-F ield or a Velocity Inlet. Normal t o the b oundar y defines the flo w dir ection using the nor mal v ectors of the boundar y sur face. If selec ted, the Direction options do not app ear.This option only app ears when the Inlet is a Velocity Inlet. Direction allo ws the sp ecific ation of thr ee t ypes of flo w dir ection a t the inlet of a P ressur e Far Field and Velocity Inlet. •Vector C omp onen ts If selec ted, the or ientation of the inlet flo w is defined b y the f ollowing unit v ector comp onen ts,Flow dir ection X ,Flow dir ection Y and Flow dir ection Z . •Vector A ngle If selec ted, the or ientation of the inlet flo w is defined b y the f ollowing angles ,Alpha (X-Y ) [deg] and Beta (X-Z) [deg] . •Case settings If selec ted, the or ientation of the inlet flo w is defined b y the or ientation used in the case file . Direction mo de allo ws the definition of t wo types of flo w dir ection a t the inlet of a M ass Flow Inlet. •Direction Vector If selec ted, the or ientation of the inlet flo w is defined b y the f ollowing nor maliz ed flo w comp onen ts,Flow dir ection X ,Flow dir ection Y and Flow dir ection Z . •Normal t o Boundar y If selec ted, the or ientation of the inlet flo w is defined b y the nor mal v ectors of the boundar y sur face. Italic Fluen t and FENSAP b oundar y conditions sho wn in the mapping tables highligh t conditions tha t do not ha ve a p erfect coun terpart in F luen t Icing . •Fluen t –X/Y/Z-C omp onen t of F low D irection The F low or ientation in F luen t can b e defined b y a non-unitar y vector. However, when using Fluen t Icing , this or ientation must b e pr ovided as a nor maliz ed v ector. 4069Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting-U p a F luen t Icing S imula tion–Total Temp erature (k) When using F luen t as the A irflow solv er in F luen t Icing , write the t otal t emp erature of a mass flow or pr essur e inlet b oundar y condition t ype inside Temp erature. •FENSAP –Pressur e Static pr essur e is not supp orted b y Fluen t Icing . For FENSAP users , comput e the G auge pr essur e by subtr acting the Op erating P ressur e from the S tatic P ressur e. –Alpha and B eta angles These angles ar e not supp orted b y Fluen t Icing . In FENSAP , Alpha is the angle in the X-Y plane and B eta is the angle in the X-Z plane .Transf orm these angles t o nor maliz ed v ector c omp onen ts and imp ose them as b oundar y conditions inside Direction mo de → Direction Vector. Currently, the user in terface of F luen t Icing do es not supp ort turbulenc e boundar y conditions .To imp ose these c onditions when using •Fluen t as the Airflow solv er, set them inside the or iginal c ase file or mo dify them via the F luen t session that is link ed t o Fluen t Icing . •FENSAP as the Airflow solv er, default turbulenc e boundar y conditions ar e imp osed . –SA Eddy/laminar visc osity ratio of 1e-5 –kw-SST Eddy/laminar visc osity ratio of 1 and Turbulenc e in tensit y of 0.01. To change these default v alues , use the t ext commands [Link t o Appendix t ext commands] in the Fluen t Console windo w. For instanc e, to change the E ddy/laminar visc osity ratio t o 1e-3 and the turbulenc e in tensit y to 1e-4, type the f ollowing c ommands: –/icing/settings/set flow/turb_eddy_lam_ratio 1e-3 –/icing/settings/set flow/turb_intensity 1e-4 A zero value t o these settings will r evert them t o their default v alue . Such t ext commands c an also be sen t from F luen t Icing b y using the Send Command action, in the c ontextual menu of the c ase file. Note To lear n mor e ab out these F luen t Inlet b oundar y conditions , consult P ressur e Far-F ield Boundar y Conditions ,Velocity Inlet B oundar y Conditions , Mass-F low Inlet B oundar y Condi- tions and P ressur e Inlet B oundar y Conditions within the F luen t User's G uide .To lear n mor e about FENSAP Inlet b oundar y conditions supp orted in F luen t Icing , consult Inlets and F ar- fields – 1000-BCs . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4070Fluen t IcingParticles To ease the set-up of the Particles solv er, it is p ossible t o aut oma tically define the b oundar y conditions at the Inlet b y check ing Automa tic. In this c ase, the Properties of P articles settings ar e applied as boundar y conditions and it is assumed tha t par ticles and air flow shar e the same inlet v elocity. The f ollowing lists the b oundar y conditions of all t ypes of Particles when the Automa tic option is uncheck ed. •• Droplet B oundar y Conditions Droplet b oundar y conditions ar e available if Droplets has b een selec ted in Set-up → Particles –Droplet L WC [k g/m3] Set the w ater dr oplet c oncentration a t the Inlet. –Droplet diamet er Set the MVD of the spher ical par ticle tha t represen ts a cloud of w ater dr oplets a t the Inlet. This option is a vailable when the Break-up mo del has b een ac tivated inside Set-up → Particles → Droplets –Droplet t emp erature [K] Set the t emp erature of the cloud of w ater dr oplets a t the inlet. This option is a vailable when the Particle ther mal equa tion is enabled in Set-up → Particles . –Droplet cust om v elocity When enabled , this option allo ws the sp ecific ation of an inlet dr oplet v elocity tha t is diff erent than the air flow velocity at the inlet. In this c ase, set the v elocity comp onen ts (Droplet X v elocity [m/s] ,Droplet Y velocity [m/s] ,Droplet Z v elocity [m/s] ) of the w ater dr oplet cloud . •Crystal B oundar y Conditions Crystal b oundar y conditions ar e available if Crystals has b een selec ted in Set-up → Particles . –Crystal IC C [k g/m3] Set the ic e cr ystal c oncentration a t the Inlet. –Crystal t emp erature [K] Set the t emp erature of the cloud of ic e cr ystals a t the inlet. This option is a vailable when the Particle ther mal equa tion is enabled in Set-up → Particles –Crystal cust om v elocity When enabled , this option allo ws the sp ecific ation of an inlet ic e cr ystal v elocity tha t is diff erent than the air flow velocity at the inlet. In this c ase, set the v elocity comp onen ts (Crystal X v elocity [m/s] ,Crystal Y velocity [m/s], Crystal Z v elocity [m/s] ) of the ic e cr ystal cloud . •Vapor B oundar y Conditions Vapor b oundar y conditions ar e available if Vapor has b een selec ted in Set-up → Particles 4071Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting-U p a F luen t Icing S imula tion–Condition mo de Set the t ype of v apor b oundar y condition t o imp ose a t the inlet. –→Rela tive Humidit y [%] Set the r elative humidit y at the inlet. This v alue is defined as the r atio of par tial v apor pr essur e to the sa turation v apor pr essur e. →Vapor C onc entration [k g/m3] Set the v apor c oncentration a t the inlet. Note In the c ase of Inlet b oundar ies tha t shar e inlet and outlet c ells, the Particles solv er will iden tify the c ells tha t are inlets based on the v elocity comp onen ts of dr oplets and cr ystals that ha ve been sp ecified under Particles . Built-in Inlet t ype commands ar e available b y right-click ing the inlet t ype icon in the Outline View. Two commands ar e cur rently supp orted. •Copy from A irflow settings Copies the Properties of A irflow settings in to the Airflow submenu of the Properties of the Inlet windo w when Edit is selec ted in Conditions . •Displa y Displa ys the sur face mesh of the Inlet t ype selec ted in the Graphics windo w. 2.6.2.2. Wall Ice accr etion simula tions r equir e appr opriate air flow, vapor and icing w all b oundar y conditions .The following figur e sho ws the P roperties of each Wall b oundar y type supp orted b y Fluen t Icing . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4072Fluen t IcingAirflow In the cur rent version of F luen t Icing , all w alls ar e sta tionar y with N o slip c ondition unless other wise specified in the or iginal c ase file .The N o slip c ondition will allo w the na tural gr owth of the visc ous layer, crucial f or icing c alcula tions . The f ollowing table maps the F luen t Icing air flow w all b oundar y conditions t o Fluen t wall b oundar y conditions . Mapping of A irflow F luent I cing Wall B oundar y Conditions int o Fluent & FENSAP B oundar y Conditions . FENSAP Fluen t Fluen t Icing --------- Thermal C onditions Temp erature Temp erature (k) Temp erature [K] Heat Flux Heat Flux (w/m2) Heat Flux [ W/m2] --------- Wall R oughness Sand-gr ain roughnessHigh R oughness (Icing) / S pecified RoughnessHigh r oughness f or Icing Thermal C onditions allo ws the sp ecific ation of thr ee t ypes of ener gy equa tion b oundar y conditions at the w all. •Temp erature [K] If selec ted, specify a t emp erature at the w all. For ic e accr etion simula tions o ver a w all, set a t em- perature tha t is equal t o the adiaba tic stagna tion t emp erature + 10K. This t emp erature is used t o comput e convective hea t transf er coefficien ts in the Ic e comp onen t.Thus, the Ic e comp onen t will provide the r eal t emp erature pr ofile o ver the w all. •Heat Flux [ W/m2] 4073Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting-U p a F luen t Icing S imula tionIf selec ted, specify a hea t flux a t the w all. If all w alls of y our c omputa tional domain ar e set t o adiaba tic c onditions (z ero hea t flux), Fluen t Icing will aut oma tically ac tivate EID . EID is a f eature that impr oves the accur acy of icing c alcula tions f or high M ach numb er flo ws, imp ortant to accur ately predic t beak ic e phenomenon. For mor e inf ormation r egar ding this mo del, consult Extended Icing Data (EID) •Case settings If selec ted, the ther mal c ondition sp ecified in the F luen t case file is used . For mor e inf ormation, consult Thermal B oundar y Conditions a t Walls within the F luen t User's G uide . Wall Roughness allo ws to sp ecify t wo types of r oughness pr operties a t the w all. •High Roughness f or Icing If selec ted, specify a Roughness H eigh t (m) at the w all. By default , Fluen t Icing sets a Roughness Constan t of 0.5 in F luen t.This v alue descr ibes a unif orm sand-gr ain r oughness distr ibution. In FENSAP , the Roughness heigh t (m) par amet er alw ays applies a c onstan t roughness distr ibution and ther efore the Roughness C onstan t par amet er is not r equir ed. For ic e accr etion simula tions over a sp ecific w all, it is r ecommended t o set the r oughness heigh t to 0.0005 m, a value e xtensiv ely used dur ing v alida tion e xercises .When r unning a multishot c alcula tion, this v alue will either b e replac ed b y the r oughness distr ibution c omput ed b y the b eading mo del a t the pr evious shot , if selec ted in Set-up → Ice, or r emain c onstan t dur ing the en tire multishot c alcula tion. For mor e in- formation r egar ding the High R oughness mo del, consult Additional R oughness M odels f or Icing Simula tions (p.982). •Case settings If selec ted, the w all roughness c ondition sp ecified in the F luen t case file is used . For mor e inf orm- ation, consult Setting the R oughness P aramet ers (p.982). Particles Among all Particles type, only the v apor mo del pr ovides a w all b oundar y condition option tha t allo ws the w alls t o sta y at 100% r elative humidit y and enables e vaporation a t these w alls.To set this boundar y condition check the Vapor Wet w all condition. Ice Ice is c omput ed o ver the w alls of the c omputa tional domain. Two options ar e pr ovided under ic e, the first ( Icing ) enables or disables w alls fr om par ticipa ting in solving the PDE s of the S hallo w Water Icing M odel (SWIM), thus r educing c omputa tional time when w alls ar e disabled , the other ( Specify Heat Flux) allo ws setting a hea t flux on a w all t o examine its impac t on the ic e accr etion pr ocess. The la tter could b e used t o quick ly assess the amoun t of hea t requir ed t o pr event ice formation, for instanc e. Icing , just under Ice, is divided in to fiv e options: •Enabled This is the default setting under Icing and it allo ws this w all t o be par t of the c omputa tional domain of SWIM. •Disabled Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4074Fluen t IcingIf selec ted, it will r emo ve this w all fr om the c omputa tional domain of SWIM. •Enabled - S liding If selec ted, it will allo w the w all t o tak e par t of the c omputa tional domain of SWIM, but no ic e will be allo wed t o accr ete over this w all.The w all will ac t as a sliding sur face for adjoining sur faces, that can accr ete ice, to slide on. •Disabled - S liding If selec ted, it will r emo ve this w all fr om the c omputa tional domain of SWIM. However, the w all will act as a sliding sur face for adjoining sur faces, tha t can accr ete ice, to slide on. •Sink If selec ted, liquid w ater film will not b e allo wed t o en ter this w all and this w all will ac t as an e xit. Built-in w all c ommands ar e available b y right-click ing the Wall icon in the Outline View.Two com- mands ar e cur rently supp orted. •Set Temp erature to Adiaba tic+10 Sets a t emp erature to the w all tha t is equal t o the adiaba tic stagna tion t emp erature, using the Properties of A irflow settings , plus 10 K. In this manner , inside the Airflow submenu of the Properties of the w all windo w, the Thermal C onditions will aut oma tically swit ch t o Temp erature and the appr opriate temp erature will b e sho wn ne xt to Temp erature [K] . •Displa y Displa ys the sur face mesh of the w all selec ted in the Graphics windo w. 2.6.2.3. Outlet Types One outlet t ype is cur rently supp orted b y Fluen t Icing . It is the Pressur e Outlet . Only one field c an b e mo dified thr ough the Properties windo w of tha t boundar y condition. It is the Gauge P ressur e [P a] and it c orresponds t o the Gauge P ressur e (pasc al) in F luen t.The G auge P ressur e is the r esult of subtr acting the Op erating P ressur e from the S tatic P ressur e variable used in FENSAP to sp ecify a Subsonic outlet. Note If mor e Pressur e Outlet settings ar e requir ed, for instanc e mor e settings c ould b e needed in or der t o define flo w reversal c onditions a t the outlet , add them inside the or iginal c ase file or thr ough the F luen t session c onnec ted t o Fluen t Icing . 4075Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting-U p a F luen t Icing S imula tion2.6.3. Solve In Solve, you will define the solv er settings of y our F luen t Icing simula tion including monit oring, ini- tializa tion and output files f or each of its F luen t Icing c omp onen ts (Airflow,Particles and Ice).These solv er settings will allo w you t o conduc t the fiv e simula tion sc enar ios men tioned in Set-up (p.4048 ) as long as the y ha ve been pr operly selec ted in the Properties of S et-up windo w. The Properties of S olve windo w pr ovides the multishot and gener al settings f or all F luen t Icing comp onen ts. •Multi-shot The M ulti-shot menu in Properties of S olve is only a vailable when all thr ee solv er types ha ve been selec ted in the Properties of S et-up . See Multi-S hot (p.4086 ). •Global settings This submenu sets the c ommon output and monit oring settings of all F luen t Icing c omp onen ts. –Plot up date in terval Controls the fr equenc y of r esidual output and v ariables tha t are monit ored. A v alue of 0 disables all plotting . –Auto-sa ve solutions Automa tically sa ves the solution of each F luen t Icing c omp onen t. –Log verb osit y Controls the amoun t of c onvergenc e and e xecution inf ormation displa yed ( Minimal ,Complet e, Detailed ) inside the Console windo w. Its content varies f or each F luen t Icing c omp onen t. –Save convergenc e to file Writes c onvergenc e files f or each F luen t Icing c omp onen t inside y our w orking dir ectory →*.fconverg for the Airflow comp onen t when using FENSAP . →*.iconverg for the Ice comp onen t Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4076Fluen t IcingThese c onvergenc e files c ontain the hist ory of y our r esiduals . Fluen t Icing c omp onen ts sho wn under Solve in the Outline View windo w ar e acc ompanied b y an icon t o their lef t.This ic on r eports if a solution file has b een loaded or c omput ed.The f ollowing table shows these ic ons. Ice Particles Airflow Solution not loaded or comput ed Solution loaded or comput ed To run a multishot c alcula tion, first c omplet e the set-up of all the F luen t Icing c omp onen ts under Solve, then r ight-click the Solve icon in the Outline View and selec t Run multishot . 2.6.3.1. Airflow The Properties of A irflow windo w under Solve permits the c onfigur ation of the air flow solv er, monit or and output par amet ers. Depending on the Airflow solv er selec ted in Set-up , the Properties of A irflow windo w will sho w either F luen t or FENSAP par amet ers. Only st eady-sta te air flow simula tions are supp orted in F luen t Icing . Fluent P roperties of A irflow Windo w Only the Numb er of it erations to run a st eady calcula tion is supp orted in this windo w. Other F luen t Solution UI par amet ers, such as Metho ds,Controls,Monit ors,Initializa tion , etc., must alr eady be presen t in the or iginal c ase file or mo dified via the F luen t session link ed t o Fluen t Icing . The Results - F luen t submenu sho ws tha t a da ta file has b een loaded or c omput ed when Loaded is check ed. An additional option is a vailable in this windo w when an Ic e solution with b eads has b een pr eviously run and loaded t o your F luen t Icing simula tion. It is the Roughness fr om b eading . By enabling this option, the r oughness distr ibution c omput ed b y the b eads mo del will b e applied as a boundar y pr ofile on all w alls wher e the High r oughness – Icing mo del has b een enabled .The Roughness H eigh t (m) of these w alls will b e up dated t o ICE3D Roughness file , which uses the ROUGHNESS boundar y pr ofile , the sand-gr ain b eads pr ofile , comput ed b y Ice. 4077Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting-U p a F luen t Icing S imula tionFENSAP P roperties of A irflow Windo w The Properties of A irflow windo w contains the most c ommon st eady-sta te solv er and monit oring settings of the FENSAP air flow solv er. The Time in tegration (FENSAP) submenu allo ws the set-up of the pseudo time st ep numb er,CFL , as w ell as the Numb er of it erations to use dur ing the simula tion. If convergenc e pr oblems ar e en- coun tered, reduc e the CFL or ac tivate the CFL r amping it erations option and sp ecify a numb er of CFL r amping it erations .This option giv es acc ess t o a mechanism tha t linear ly incr eases the CFL numb er fr om 1, at the star t of the simula tion, to its full v alue a t the end of the CFL r amping it erations . The Output submenu allo ws the cr eation of numb ered solution files and of the most c ommon monit oring v ariables t o track in or der t o guar antee full c onvergenc e of the FENSAP solv er. •Forces By default ,No lif t and dr ag coefficien ts ar e outputt ed dur ing the simula tion. However, if Forces is set t o Drag-C ustom dir ection , resultan t lift, drag and momen t coefficien ts (on all w alls) will b e monit ored dur ing the simula tion. These aer odynamic c oefficien ts ar e comput ed using the C onditions defined in Set-up → Airflow and the f ollowing par amet ers. –Lift axis Provide the p ositiv e or ientation of lif t along the p ositiv e or nega tive X, Y and Z axis . FENSAP will obtain its tr ue dir ection based on this inf ormation and the dr ag dir ection. –Drag – X ,Drag – Y,Drag – Z Provide the non-dimensional dir ection of dr ag in C artesian c oordina tes. –Referenc e ar ea Specify a r eference ar ea in m2 tha t is used t o comput e the aer odynamic c oefficien ts. –Momen t – X ,Momen t – Y,Momen t – Z Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4078Fluen t IcingSpecify a p oint in the c omputa tional domain tha t will ac t as the momen t center to comput e the aerodynamic momen t coefficien t. •Numb ered solution files If selec ted, specify the fr equenc y,Iterations b etween output , at which FENSAP solutions ar e going to be wr itten inside y our w orking dir ectory.This option do es not o verwrite solution files and ther efore an it eration numb er will b e assigned as a suffix t o the air flow solution file name . Make sure tha t you ha ve enough disk spac e when y ou selec t this option. •Monit or - Total H eat If selec ted, monit ors the t otal c onvective hea t flux using all the w alls of the c omputa tional domain. •Monit or -M ass F low If selec ted, monit ors the mass inflo w, outflo w and deficit of air inside the c omputa tional domain. •Monit or -H eat Flux If selec ted, monit ors the t otal en thalp y inflo w, outflo w and deficit of the c omputa tional domain. An additional option is a vailable in this windo w when an Ic e solution with b eads has b een pr eviously run and loaded t o your F luen t Icing simula tion. It is the Roughness fr om b eading . By enabling this option, the r oughness distr ibution c omput ed b y the b eads mo del will b e applied as a boundar y pr ofile on all w alls wher e the High r oughness – Icing mo del has b een enabled .The Roughness H eigh t (m) of these w alls will b e up dated t o ICE3D Roughness file , which uses the ROUGHNESS boundar y pr ofile , sand-gr ain b eads pr ofile c omput ed b y Ice. Airflow C ommands Built-in air flow commands ar e available b y right-click ing the Airflow icon under Solve in the Outline View.The f ollowing c ommands ar e cur rently supp orted. •Initializ e 4079Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting-U p a F luen t Icing S imula tionExecut es an initializa tion of the air flow solv er using the Initializa tion settings of F luen t or in the case of FENSAP , the C onditions and D irection par amet ers in Set-up → Airflow. •Calcula te Launches the simula tion of the Airflow comp onen t. If a solution is loaded , the simula tion will continue fr om tha t loaded solution. Other wise ,Calcula te will first Initializ e and then use this solution t o solv e the PDE s of the Airflow comp onen t. •Interrupt Stops the e xecution of the air flow solv er a t the end of the ne xt iteration. The solution is k ept in memor y. •Load/S ave/Save as… Load or sa ve files in to or fr om y our Airflow simula tion. 2.6.3.2. Particles Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4080Fluen t IcingThe Properties of P articles windo w contains the most c ommon st eady-sta te solv er, initializa tion and monit oring settings of the F luen t Icing Particles solv er, DROP3D . The Run settings submenu allo ws the set-up of the Numb er of it erations to conduc t dur ing the it- erative simula tion. The Solver submenu is divided in to thr ee p oints, the pseudo time st ep, the ar tificial visc osity and the c onvergenc e cr iteria. •CFL •The r ecommended v alues f or the CFL range b etween 10 and 20. If convergenc e pr oblems ar e enc oun tered, reducing the CFL migh t help . •Artificial Visc osit y coef The P articles c omp onen t uses the S treamline up wind (SU) t echnique t o stabiliz e the PDE s.This scheme is c omplemen ted with a user-set cr osswind diffusion. Its default v alue is 1e-5 and has b een extensiv ely used in a lar ge numb er of v alida tion c ases . In the c ase of str uctured gr ids, you c an in- crease this v alue t o 1e-4 if y ou e xperienc e oscilla tions of L WC within the shado w zone . Its impac t to collec tion efficienc y is gener ally minimal. Crosswind dissipa tion sc ales with mesh siz e, similar t o the up wind scheme , and is lo wer with finer gr ids. •Residual cut-off The Residual cut-off is the st opping cr iterion of the o verall residual of the Particles governing equa tions . Lower the default v alue of 1e-8, esp ecially if y ou ar e in terested in c aptur ing shado w zones . •Change in t otal b eta This par amet er is the diff erence in t otal c ollec tion efficienc y of all w alls b etween t wo consecutiv e iterations . It is thus a measur e of c onvergenc e of the numb er of par ticles (dr oplets or cr ystals) tha t hit the w alls of the c omputa tional domain. Lower the default v alue of 1e-10 if y ou see diff erences in collec tion efficienc y between pr intouts . The Initializa tion submenu allo ws the initializa tion of the par ticle c oncentration and par ticle v elocity fields . •Velocity Two initializa tion choic es ar e off ered f or the v elocity field . –From A irflow conditions If selec ted, the Speed and Direction inside of Set-up → Airflow are used as the initial v elocity of all t ypes of par ticles a t all no des in the c omputa tional domain. –Cartesian c omp onen ts If selec ted, specify the v elocity comp onen ts (X velocity [m/s] ,Y velocity [m/s] and Z velocity [m/s] ) tha t will b e assigned as the initial v elocity for all par ticles inside the c omputa tional domain. •Dry Initializa tion 4081Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting-U p a F luen t Icing S imula tionIf selec ted, sets the par ticle c oncentration (L WC, ICC or Vapor Humidit y) to zero everywher e inside the c omputa tional domain e xcept a t the inlet , wher e Particles b oundar y conditions ar e defined . Other wise , the P articles c oncentration sp ecified in S et-up → Particles will b e used t o initializ e the computa tional domain. The Output submenu c ontains t wo options: Numb ered solution files and Save distr ibution solutions . •Numb ered solution files If selec ted, specify the fr equenc y,Iterations b etween output , at which Particles solutions wr itten inside y our w orking dir ectory.This option do es not o verwrite solution files and thus an it eration numb er will b e assigned as a suffix t o the Particles solution file name . Make sur e tha t you ha ve enough disk spac e when y ou selec t this option. •Save distr ibution solutions Selec t this option if y ou w ould lik e to sa ve all the solutions of a distr ibution simula tion. The solutions will b e numb ered fr om 1 t o the t otal numb er of par ticles siz es tha t define this distr ibution. The numb er 1 will b e assigned t o the lar gest par ticle siz e and the last numb er to the smallest par ticle size. The Monit ors submenu allo ws the tr acking of c onvergenc e of sur face in tegral quan tities such as collec tion efficienc y, mass deficit and v apor c ondensa tion. •Total B eta –If selec ted, monit ors the t otal c ollec tion efficienc y comput ed on all w alls of the c omputa tional domain. •Change in Total B eta –If selec ted, monit ors the diff erence in t otal c ollec tion efficienc y of all w alls b etween t wo consecutiv e iterations . •Mass deficit –If selec ted, monit ors the mass inflo w, outflo w and deficit of par ticles inside the c omputa tional domain. •Vapor c ondensa tion –If selec ted, monit ors the t otal v apor condensa tion on all the w alls of the c omputa tional domain. Note In a par ticle distr ibution simula tion, each par ticle siz e simula tion is e xecut ed in sequenc e. Their r esiduals gr aph is displa yed a t the end of the e xecution and will pr esen t a summar y of the c onvergenc e of each c alcula tion. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4082Fluen t IcingParticles C ommands Built-in par ticles c ommands ar e available b y right-click ing the Particles icon under Solve in the Outline View.The f ollowing c ommands ar e cur rently supp orted. •Initializ e Execut es an initializa tion of the Particles solv er using the Initializa tion settings inside the Solve → Particles property windo w. •Calcula te Launches the simula tion of the Particles comp onen t. If a solution is loaded , the simula tion will continue fr om tha t loaded solution. Other wise ,Calcula te will first Initializ e and then use this initial solution t o star t solving the PDE s of the Particles comp onen t. •Load Load a Particles solution t o your F luen t Icing simula tion. •Save Droplets Saves only the w ater dr oplet solution files of y our Particles simula tion. The name of this file will be your c ase filename (without the .cas suffix) f ollowed b y .droplet . •Save Crystals Saves only the ic e cr ystal solution file of y our Particles simula tion. The name of this file will b e your c ase filename (without the .cas suffix) f ollowed b y .crystal . •Save Vapor Saves only the v apor solution file of y our Particles simula tion. The name of this file will b e your case filename (without the .cas suffix) f ollowed b y .vapor . 4083Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting-U p a F luen t Icing S imula tion•Reset Unloads the Particles solutions . 2.6.3.3. Ice The Properties of Ic e windo w contains the most c ommon time , initializa tion and output settings of the Ic e solv er, ICE3D . The Time submenu allo ws the set-up of the Total time of ic e accr etion [s] and the t ype of time st ep. •Total time of ic e accr etion [s] This is the t otal ph ysical time dur ation of the Ic e simula tion. •Automa tic time st ep By default , this option is check ed.The stable time st ep f or an e xplicit time in tegration scheme de- pends on fluid sp eed and lo cal mesh sizing . For time accur ate pr oblems , all c ontrol volumes ha ve to use the same time st ep. Automa tic time st epping r emo ves the guess w ork of sp ecifying a stable time st ep. In this manner , this option c omput es the optimal time st ep f or each gr id/film sp eed combina tion and lar gely r educ es y our c omputa tional time . If disabled , a Time st ep [s] option ap- pears , wher e you c an define a stable time st ep f or the Ice simula tion. The Initializa tion submenu allo ws the c ontinua tion of a simula tion fr om an e xisting ic e solution. If an ic e solution has b een loaded or obtained , the Restar t from cur rent solution becomes a vailable and , if selec ted, the Ice simula tion will use the loaded or obtained solution as a star ting p oint of the unst eady ice calcula tion. Note By default ,Calcula te will r un the Ic e simula tion without c onsider ing loaded files as initial solutions .To star t the c alcula tion fr om a giv en solution, you must initializ e your simula tion by using Restar t from cur rent solution . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4084Fluen t IcingThe Output submenu allo ws the selec tion of the t ype of Ice simula tion t o conduc t. •Run icing Runs the SWIM as w ell as the ic e shap e mo del and ther efore pr oduces an ic e solution. This option is check ed (enabled) b y default. •Run gr id displac emen t If selec ted, this option will output a 3D gr id displac ed b y the accumula ted ic e on the solid boundar ies.Therefore, this option r equir es an ic e solution. When selec ted with Run icing , the Run icing is e xecut ed first and then the Run gr id displac emen t follows.When Run gr id displac emen t is the only option selec ted in Output , an ic e solution must b e loaded . Note In a multi-shot simula tion, Run icing and Run gr id displac emen t are aut oma tically e xecut ed in sequenc e. After gr id displac emen t, the w alls and the sur rounding c ells ar e displac ed/def ormed t o take in to acc oun t the new ic e shap e.The ne xt step in this pr ocess w ould b e to run the airflow solv er on this new gr id in or der t o obtain the lo cal air flow conditions and pr operties around the new ic e shap e. Further c alcula tions (par ticles and ic e) ar e obtained on the up- dated mesh. Therefore, each shot has its o wn gr id/c ase file . The Result submenu app ears if an ic e solution has b een Loaded (loaded or c alcula ted). This is also displa yed in the Outline View windo w b y the ic on next to Solve → Ice. Ice Commands Built-in ic e commands ar e available b y right-click ing the Ice icon under Solve in the Outline View. The f ollowing c ommands ar e cur rently supp orted. •Calcula te Launches the simula tion of the Ic e comp onen t based on the settings defined in Solve → Ice. 4085Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting-U p a F luen t Icing S imula tion•Load Loads an Ice solution t o your F luen t Icing simula tion. To use this solution as a r estar t, enable Restar t from cur rent solution inside the pr operties windo w of Solve → Ice. •Save Saves all Ice solution files of y our simula tion. The name of these files will b e your c ase filename (without the .cas suffix) f ollowed b y .ice.* .The suffix es * ar e ice.grid ,map.grid and swimsol . For mor e inf ormation r egar ding these output files , consult Results (p.4087 ). •Reset Unloads the Ice solution. 2.6.3.4. Multi-Shot A multi-shot r un e xecut es the thr ee solv ers ( Airflow,Particles ,Ice) in sequenc e. This option allo ws the c ontrol of the numb er of quasi-st eady shots ,Numb er of shots , to simula te and the sa ving of output files of Airflow,Particles and Ice at each shot ,Save files a t each shot , for futur e post-pr ocessing if needed . •Numb er of shots This option allo ws the c ontrol of the numb er of quasi-st eady shots t o simula te, which is one instanc e of Airflow – Particles – Ice calcula tion. Grid displac emen t is e xecut ed a t the end of each shot and used as an input f or the ne xt step. •Save files a t each shot The solution of each solv er st ep will b e sa ved in separ ate files on the disk, alongside the c ase file . The files ar e numb ered f or each shot , for e xample casefilename.02.droplet is the dr oplet solution f or shot #2. Multi-Shot C ommands Built-in multi-shot c ommands ar e available b y right-click ing the Solve icon in the Outline View.The following c ommands ar e cur rently supp orted. •Run multishot Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4086Fluen t IcingExecut es the multi-shot sequenc e for Numb er of shots .The cur rent sta te of the e xecution (solv er and shot st ep) is displa yed in the Outline View.The gr id file is displac ed with the ic e shap e at the end of each shot. •Interrupt Stops the multi-shot c omputa tion a t the cur rent step.The solution is sa ved a t the cur rent sta te. This is a vailable when the multi-shot simula tion is r unning . •Reset Resets and unloads all solutions .This is equiv alen t to executing Reset on each Airflow,Particles and Ice tree no des.The gr id file is not r eset b y this op eration. If the Airflow solv er is F luen t,Reset will e xecut e an initializ e op eration on the air flow solution. Note The multi-shot mor phs the gr id with the ic ed w all sur faces a t each shot. The Reset op- eration will r eset solutions , but will not load the or iginal gr id no de lo cations .To revert to a sp ecific shot , or the or iginal gr id, use the File → Open menu and selec t the appr o- priate case file t o load . Loading a c ase file will also load its settings in F luen t Icing . A multi-shot sequenc e can b e manually set b y executing the Airflow,Particles ,Ice solv ers one af ter the other . In this c ase, enable Run gr id displac emen t in Solve → Ice to acc oun t for ic e shap e up dates within the 3D gr id and , if the Beading mo del is used , active Roughness fr om b eading in Solve → Airflow to consider the impac t of the sand- grain r oughness pr oduced b y the b eads on to the air flow. 2.6.4. Results The Results sec tion in the Outline View provides acc ess t o the c ore Fluen t postpr ocessing options as pr esen ted in the R emot e Visualiza tion C lient and off ers the same options as in F luen t’s user in terface. The diff erent objec t types off ered under Result → Graphics are: •Meshes Displa ys the cur rent mesh sur faces. 4087Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting-U p a F luen t Icing S imula tion•Contours Displa ys contours of solution fields o ver sur faces.The r esults of F luen t Icing ar e list ed in the Icing variable c ategor y.The list of a vailable F luen t Icing fields will dep end on the solution files cur rently loaded (air flow, droplets , crystals , vapor, ice). All Fluen t Icing fields ar e solutions defined a t the no des. •Vectors Displa ys vector solution fields in the en tire computa tional domain or on selec ted sur faces. Only supp orted f or F luen t air flow solution v ariables . Use Viewmer ical or CFD-P ost t o post-pr ocess FENSAP , Particles and Ice vector solutions . •Pathlines Displa ys flo w and par ticle pa ths within the c omputa tional domain. Only supp orted f or F luen t air flow solution v ariables . Use Viewmer ical or CFD-P ost t o post-pr ocess Particles and Ice pathlines . Some mesh and c ommon F luen t Icing fields c an b e view ed quick ly by using Quick-vie w. See the ne xt section f or mor e details . To cr eate and displa y a new gr aphic objec t: Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4088Fluen t Icing•Right-click on the objec t type of in terest ( Meshes ,Contours , etc.), and selec t New or use the c ommand butt ons in the View windo w of the R ibbon. •In the Property windo w, set-up the gr aphic al objec t options , and cho ose the Surfaces to displa y. A de- scription on ho w to gener ate these objec t types c an b e found inside B asic G raphics G ener ation of the Fluen t User's G uide . •Selec t Displa y in the c ontextual menu of the new objec t to output the r esult in the G raphics windo w. 4089Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting-U p a F luen t Icing S imula tion2.6.4.1. Quick-Vie w Quick-view p ermits t o easily output the most c ommon F luen t Icing fields on w alls and other b oundar y surfaces. A Fit to Windo w view is applied in all c ases b y default. Note Quick-view will use the solution da ta of the cur rently selec ted F luen t case file .To output the solution of another F luen t case within the Outline View, selec t the desir ed c ase b efore running Quick-vie w. Three objec t types ar e supp orted in Quick-vie w. Mesh •All boundar ies Displa ys the b oundar y sur face meshes of c omputa tional domain (inlet , outlet , wall, symmetr y) •Walls only Only the w all sur faces ar e displa yed. •Mesh – Viewmer ical Opens Viewmer ical with the mesh of the simula tion c ase. •Mesh – CFD-P ost Opens CFD-P ost with the mesh of the simula tion c ase. Contours •Airflow –FENSAP/F luen t – Temp erature (w alls) → Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4090Fluen t IcingDispla ys the t emp erature distr ibution on all w alls. →Heat flux (w alls) Displa ys the c onvective hea t flux distr ibution on all w alls. →Velocity M agnitude Displa ys the air flow sp eed on all b oundar y sur faces. –FENSAP format only →View with Viewmer ical Opens Viewmer ical with the mesh and the air flow solution of the simula tion c ase. →View with CFD-P ost Opens CFD-P ost with the mesh and the air flow solution of the simula tion c ase. •Particles –Droplets / C rystals →Collec tion efficienc y Displa ys the c ollec tion efficienc y of the dr oplets or cr ystals on all w alls. →LWC / IC C Displa ys the L WC or IC C on all b oundar y sur faces. →View with Viewmer ical Opens Viewmer ical with the mesh and the dr oplet or cr ystal solution of the simula tion c ase. →View with CFD-P ost Opens CFD-P ost with the mesh and the dr oplet or cr ystal solution of the simula tion c ase. •Vapor –Vapor c onc entration Displa ys vapor c oncentration on all b oundar y sur faces. –Vapor c ondensa tion Displa ys vapor c ondensa tion on all w alls. –View with Viewmer ical Opens Viewmer ical with the mesh and the v apor solution of the simula tion c ase. –View with CFD-P ost 4091Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting-U p a F luen t Icing S imula tionOpens CFD-P ost with the mesh and the v apor solution of the simula tion c ase. •Ice –Ice thick ness Displa ys the ic e thick ness on all w alls. –View with Viewmer ical Opens Viewmer ical with the sur face mesh (map.grid ) and the ic e solution ( swimsol ) of the simula tion c ase. –View with CFD-P ost Opens CFD-P ost with the sur face mesh (map.grid ) and the ic e solution ( swimsol ) of the simula tion c ase. Ice cover •Ice cover Viewmer ical / CFD-P ost Displa ys the 3D ic e shap e over the or iginal sur face. In the c ase of CFD-P ost, the displa y of the ic e shap e is done b y executing the Ice Cover – 3D-Vie w icing macr o. •Multishot ic e cover Viewmer ical / CFD-P ost Displa ys the 3D ic e shap es obtained dur ing each shot o ver the or iginal sur face. In the c ase of CFD- Post, the displa y of all ic e shap es is done b y executing the Ice Cover – 3D-Vie w icing macr o. A single quick-view it em c an b e displa yed a t a time in the Graphics windo w and will r eplac e the previous it em displa yed.To store multiple it ems in diff erent windo ws, use the Results entry in the Outline View as detailed in Results (p.4087 ). Selec ting a quick-view will r eset the cur rent view .To up date the cur rent quick view with the la test solution, use the Displa y command fr om the c ontextual menu in the Outline View. For mor e inf ormation r egar ding Viewmer ical and CFD-P ost, consult the ne xt two sec tions . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4092Fluen t Icing2.6.4.2. Viewmeric al Viewmer ical is the p ost-pr ocessor of FENSAP-ICE and c an r ead icing solutions dir ectly. Usage is detailed in Viewmer ical. Viewmer ical will r ead a gr id and solution file in FENSAP f ormat.When using the Quick-vie wViewmer- ical commands , temp orary files (*.T MP files) ar e wr itten and Viewmer ical is launched with these files . For e xample , a case file ,CASE.cas , was used t o obtain an air flow and w ater dr oplet solutions . If you decide t o op en the w ater dr oplet solution with Viewmer ical within Quick-vie w, the f ollowing t emp orary files ar e wr itten •CASE.tmp.grid This is the t emp orary FENSAP gr id file . •CASE.tmp.droplet This is the t emp orary dr oplet solution file . These t emp orary files c an b e delet ed without c ompr omising y our F luen t Icing simula tion w orkflow. Note Launching Viewmer ical requir es a P ost-pr ocessing lic ense t oken and the installa tion of the FENSAP-ICE pack age. FENSAP-ICE is par t of the default F luids installa tion pack age of ANSY S. Launching it r equir es the AWP_R OOT*** environmen t variable t o be set-up .This is aut o- matically done on Windo ws dur ing the installa tion pr ocess. See the ANSY S installa tion manual f or details 4093Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting-U p a F luen t Icing S imula tion2.6.4.3. CFD-P ost CFD-P ost is a gener al p ost-pr ocessor f or ANSY S Fluids and c an r ead icing solutions dir ectly via a command file . Usage is detailed in the CFD-P ost sec tion of the CFX-P re User's G uide . CFD-P ost is launched with sp ecial icing macr os enabling the gener ation of figur es and anima tions of ice shap es and field c ontours in 3D (Ic e Cover – 3D-V iew) as w ell as 2D P lots (Ic e Cover – 2D-P lot), their usage is detailed in the CFD-P ost M acros sec tion within the FENSAP-ICE U ser M anual. CFD-P ost will r ead a gr id and solution file in FENSAP f ormat as w ell as a c ommand file .When using the Quick-vie w CFD-P ost c ommands , temp orary files (*.T MP files) ar e wr itten and CFD-P ost is launched with these files . For instanc e, a case file ,CASE.cas , was used t o obtain an air flow and w ater dr oplet solutions . If you decide t o op en the w ater dr oplet solution with CFD-P ost within Quick-vie w, the f ollowing t emp orary files ar e wr itten: •CASE.tmp.grid This is the t emp orary FENSAP gr id file . •CASE.tmp.droplet This is the t emp orary dr oplet solution file . •Case.tmp.fsp This the t emp orary command file . These t emp orary files c an b e delet ed without c ompr omising y our F luen t Icing simula tion w orkflow. Note CFD-P ost is installed b y default with an y ANSY S Fluids pr oduc t and uses a P ost-pr ocessing license t oken. Launching it r equir es the AWP_R OOT*** environmen t variable t o be set- up, this is aut oma tic on Windo ws as the sof tware is installed . See ANSY S, Inc. Installa tion Guides f or mor e details . 2.6.5. Preferenc es The Icing preferences ar e available fr om the File → Preferenc es menu . Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4094Fluen t IcingFluen t Icing launch options ar e set-up in this windo w: •Use F luen t launcher Launches a F luen t session when op ening F luen t Icing . •Default F luen t CPU Specifies the numb er of CPU s used dur ing F luen t Icing simula tions . •Define w orking dir ectory If enabled , permits the definition of a w orking dir ectory wher e case files ar e imp orted and futur e simula tion files ar e wr itten. Its lo cation should b e defined inside the Working dir ectory text box. If disabled , futur e simula tion files will b e wr itten wher e the or iginal c ase file is lo cated. •Beta f eatures Enables B eta f eatures of Icing solv ers •Advanc ed settings See Advanced S ettings (p.4095 ) 2.6.6. Advanc ed S ettings Some e xpert level options ar e una vailable a t the star t of F luen t Icing as the y are rarely used dur ing icing simula tions .These options should b e used with c autious .When the Advanc ed settings option is enabled in P references, the f ollowing e xtra options app ear in F luen t Icing . •Turbulenc e Schmidt numb er Appears in Set-up → Particles → Vapor.The Turbulen t Schmidt numb er is pr oportional t o the turbulen t mass diffusion c oefficien t of the v apor tr ansp ort equa tion. Therefore, it c ontrols the r ate of pr opaga tion of w ater v apor. Its default numb er is set t o 0.7 and has b een used in se veral valida tion cases . •Disable EID P repr ocessing Appears in Solve → Ice. In some sc enar ios r elated t o Adiaba tic w alls (see Boundar y Conditions (p.4064 ), Inlet Types (p.4065 ),Airflow (p.4050 ) and H eat Flux under Ice (p.4062 )), the EID pr e-pr ocessing will b e execut ed, prior t o executing the Ice solv er. If this option is enabled , the EID pr eprocessing will b e skipped. If the EID w as alr eady comput ed on to the cur rent air flow, the Ic e simula tion will use the 4095Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting-U p a F luen t Icing S imula tionexisting EID solution. If EID w as not c omput ed on to the cur rent air flow, the Ice simula tion will use the solution without the pr e-pr ocessing . Note The EID pr eprocessing is manda tory for simula tions inc orporating v apor tr ansp ort. •Save GMRES t o file Appears in Solve.This option sa ves an additional file , the *.*gmres file, to monit or c onvergenc e of the GMRES solv er in FENSAP and P articles . •Heat Flux Appears in Set-up → Ice.This option allo ws the selec tion of t wo types of c onvective hea t flux pr o- duced b y FENSAP in or der t o conduc t an ic e accr etion simula tion. –Classic al Convective hea t flux es c omput ed using t emp erature gr adien ts on the w alls.This metho d is 2nd order accur ate and is the default option when Advanc ed settings is disabled . –Gresho Convective hea t flux es c omput ed based on G resho ’s Consist ent Galerkin formula tion. Gresho fluxes tend t o exhibit oscilla tions when the sur face gr id is une ven or c oarse and ther efore it is less r obust than Classic al. 2.6.7. File Types The f ollowing descr ibes the t ype of files gener ated/loaded/imp orted b y Fluen t Icing: •Starting Input F ile *.cas Fluen t case file . Contains the gr id and c onfigur ation of y our F luen t/Fluen t Icing simula tion. *.cas.gz (compr essed c ase file) and *.cas.h5 (HDF / CFF case file) c an also b e used . •Airflow *.dat Fluen t air flow solution file *.dat.gz and *.dat.h5 are used , if the c ase file is in .gz or .h5 format. •*.soln FENSAP air flow solution file . •Particles Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4096Fluen t Icing*.droplet Water dr oplet solution file . *.crystal Ice cr ystal solution file . *.vapor Vapor solution file . •Ice accr etion *.swimsol Ice solution file (c an b e view ed with map.grid or ice.grid ). *.map.grid Surface mesh of w alls tha t ha ve been enabled f or icing . *.ice.grid Surface mesh of the ic e shap e pr oduced b y walls tha t ha ve been enabled f or icing •Ice accr etion – extra files . *.swimsol.s2g Mapping file t o load a swimsol (areal solution) in F luen t. Automa tically loaded/sa ved alongside a swimsol file. Requir ed f or F luen t Icing . *.rough Roughness pr ofile when b eading is enabled . *.disp Displac emen t profile tha t represen ts the v olumetr ic accr etion of ic e. •Residuals (if Save convergenc e to file is enabled in Solve). *.fconverg FENSAP air lfow convergenc e. *.fgmres FENSAP air flow GMRES r esiduals . *.pconverg Particles c onvergenc e. •FENSAP gr id (if Write FENSAP ... grid is selec ted under File → Export). 4097Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting-U p a F luen t Icing S imula tion*.grid FENSAP gr id file .This gr id can b e used in Viewmer ical or CFD-P ost t o view P articles solution files . •Multishot *.01.* Files r elated t o the first shot. *.02.* Files r elated t o the sec ond shot. Etc. •Control files *.abort Batch mo de c omputa tion in terruption file . See In terrupting a C omputa tion under Fluen t Journal Commands (p.4101 ). cleanup-fluent-*.bat / cleanup-fluent-*.sh Script file enabling a k ill of the F luen t process and subpr ocesses .This is not r equir ed in r egular e xe- cution mo de. cleanup-flicing-*.bat / cleanup-flicing-*.sh Script file enabling a k ill of the F luen t Icing pr ocess. •Temp orary files – Can b e saf ely er ased af ter execution fluent-*-error.log Temp orary log files f or F luen t error c onditions . serverinfo.* File used t o connec t Fluen t Icing t o the F luen t ser ver, also gener ated b y running File → Applic ations → Icing or File → Applic ations → Server → Start in F luen t main applic ation. .cmd.3dview* ,*.3dtmp Cache files used b y Viewmer ical. *.fsp Command file used t o launch CFD-P ost. *.tmp.* Temp orary gr id & solution files used t o launch Viewmer ical or CFD-P ost. Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4098Fluen t Icing2.6.8. Appendix 2.6.8.1. Python C ommands Many of the icing f eatures and settings c an b e acc essed and changed thr ough the Console windo w, using p ython c ommands . The same c ommands c an b e used t o aut oma te the F luen t Icing applic ation, by launching it with the -R argumen t, as in: Linux bin/icing -wait -R file.py Windo ws bin/icing.bat -wait -R file.py The -wait argumen t waits un til the e xecution is c omplet ed, before resuming ba tch e xecution. Without the -wait command , the F luen t Icing applic ation is sen t to back ground). Note The ba tch mo de r equir es a gr aphic al displa y.To run a c ase file in ba tch, use Fluen t Journal C ommands (p.4101 ). Python C onsole & O perations The Console windo w at the b ottom r ight corner of the F luen t Icing applic ation p ermits t o en ter commands in teractively.The f ollowing sec tions descr ibe commands a vailable in the p ython c onsole dir() and the c ommand/a ttribut e list dir() Displa y the list of global c ommands and t op-le vel objec ts. 'AddS ession', 'ReadScr iptF ile', 'Remot eSession', 'StartTranscr ipt', 'StopT ranscr ipt' dir(object Displa y the list of c ommands & a ttribut es of the objec t. Example 2.2: Entering C ommands In teractively (Assuming t est1.c as is alr ead y loaded) dir(RemoteSession[“test1.cas”]) 'Case', 'Connec t', 'Connec tionInf o', 'IcingS imula tion', 'StartServer' r = RemoteSession[“test1.cas”] # A temp orary variable c an b e used t o simplify c ommand lines . 4099Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting-U p a F luen t Icing S imula tiondir(r.Case.Icing.Particles) 'Crystals', 'Droplets', 'Model', 'Type', 'Vapor' dir(r.Case.Icing.Particles.Droplets.Particles.Droplets.Conditions) ' Appendix', 'Diamet er', 'LWC', 'SLDF lag', 'WaterD ensit y' Accessing/C hanging v alues The () op erator will r etur n the cur rent value of the a ttribut e. RemoteSession[“test1.cas”].Case.Icing.Particles.Conditions.LWC() 0.001 RemoteSession[“test1.cas”].Case.Icing.Particles.Conditions.LWC = 0.00344 Commands If an it em list ed in dir() is a v erb, it is a c ommand . For e xample AddSession() RemoteSession[“test1.cas”].Case.Icing.Solution.ParticlesRun.Calculate() Sample scr ipt # Add sesssion and load case file AddSession() r = RemoteSession["RemoteSession1"] r.IcingSimulation.Inputs.CaseFile = "grid.cas" r.IcingSimulation.Inputs.DataFile = "grid.dat" r.StartServer() # Airflow: already set-up in case file (Fluent airflow) # Droplets: Configure r.Case.Icing.Particles.Droplets.Conditions.Diameter = 16 r.Case.Icing.Solution.ParticlesRun.Solver.CFL = 10 r.Case.Icing.Solution.ParticlesRun.RunSettings.NumIterations = 140 # Wait until the boundary conditions are loaded and available to set-up waitTrue(r.Case.Icing.IcingBC) # Setup boundary conditions bc = r.Case.Icing.IcingBC["velocity-inlet-4"] bc.ParticlesInlet.AutoBC = False bc.ParticlesInlet.DropletDiameter = 16 bc.ParticlesInlet.DropletTemperature = 270 bc.ParticlesInlet.DropletVelocityFlag = True bc.ParticlesInlet.DropletVelZ = 40. # Compute droplets r.Case.Icing.Solution.ParticlesRun.Calculate() r.Case.Icing.Solution.ParticlesRun.SaveDroplets(Filename="test1.droplet") # This script will stop after execution. r.Disconnect() Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4100Fluen t Icing2.6.8.2. Fluent J ournal C ommands Onc e a c ase is c onfigur ed in the Icing applic ation and sa ved, it c an b e used in ba tch mo de sc enar ios wher e a r egular F luen t jour nal file is used . Use regular F luen t jour nal file c ommands t o execut e standar d Fluen t op erations: •Load/sa ve the c ase file •Load/sa ve the da ta file (.dat ) •Initializ e/Iterate the F luen t air flow solution •Etc. In a c ase file wher e icing w as set-up with the F luen t Icing applic ation, the t ext command en vironmen t will pr ovide the icing/ submenu and c ommands: •icing/ –file/ –settings/ –flow/ –drop/ –ice/ –multishot/ •file/ commands –load-file / save-file →Load or sa ve a single solution file , of a sp ecified t ype –load-all / save-all →Load or sa ve all solution files asso ciated with a .cas For FILE.cas , the default output filename is the filename without the suffix (FILE). The c ommand w ould wr ite FILE.droplet ,FILE.swimsol , etc. –reset-file →Unload a sp ecific solution t ype –reset-all →Unload fr om memor y all icing solutions (FENSAP air flow, par ticles , ice) –status 4101Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting-U p a F luen t Icing S imula tion→List the cur rently loaded icing solutions , and their t ype •settings/ –get variable –set variable value →Individual icing settings c an b e acc essed and changed thr ough these c ommands . Advanc ed users: The settings ar e the rpv ar name without the f ensapic e/ pr efix –auto-save? →Toggle the aut o-sa ve feature, which is wr iting solutions t o files a t the end of an y icing solv er run (airflow, par ticles , ice).The file is wr itten alongside the c ase file (FILE.cas will ha ve FILE.droplet , etc.) –save-converg? save-gmres? →Toggle t o sa ve the c onvergenc e detail of icing solv ers in t ext files alongside the c ase file –verbosity →Set the lo g output v erbosity for icing solv ers. Default is 0 (minimal), set t o 1 (C omplet e) to get addi- tional inf ormation on the solv er execution. •flow/ c ommands (FENSAP only . Use F luen t text commands f or the F luen t air flow solv er). –init →Starts and initializ e the solv er. →This is aut oma tically done when r unning c alcula te() f or the first time , or b y running calculate() after running the solv er fr om another mo de (FENSAP air flow, par ticles , ice or gr id displac emen t). –calculate →Calcula te FENSAP air flow for the numb er of it erations cur rently set-up in the flo w/nit er variable . →Multiple c alcula te commands c an b e execut ed, continuing the c omputa tion alr eady star ted. →Example 2.3: Use the Icing/S ettings/S et C ommand t o Set the N umb er of I terations Icing/settings/set flow/niter 250 →end Release solv er memor y •drop/ commands (P articles solv er) –init ,calculate ,end (Similar t o flo w/ c ommands) Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4102Fluen t Icing→The numb er of it erations is in drop/niter setting . •ice/ commands –run →Runs the icing solv er (and/or gr id displac emen t) The t otal time is in the setting ice/ice_total_time –end →Release solv er memor y •multishot/ commands –run →Runs the cur rently c onfigur ed multishot If icing settings ar e not par t of y our or iginal c ase file , the c ommand (load-f ensapic e) can b e used t o enable the icing solv er commands and t o displa y the icing/ menu . A c ase file set-up with the Icing applic ation will aut oma tically load the icing mo dule when it is r ead. Note The full set-up and e xecution of the icing settings thr ough t ext commands is p ossible sinc e all the icing settings ar e stored as rpvars and thread variables . Interrupting a c omputa tion On the in teractive terminal of FENSAP ,Ctrl+C will st op the c omputa tion a t the end of the cur rent it- eration. When r unning in ba tch mo de, the ab ort file (*.abort ) can b e used .The ab ort file is a simple text file c ontaining the “stop” keyword. For e xample , for casefilename.cas echo st op > c asefilename .abort This will in terrupt the solv er a t the end of the cur rent time st ep, this will not tr igger a jour nal file er ror and the e xecution will c ontinue t o the ne xt steps. 4103Release 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es.Setting-U p a F luen t Icing S imula tionRelease 2019 R3 - © ANSY S, Inc. All rights r eser ved. - Contains pr opr ietar y and c onfidential inf ormation of ANSY S, Inc. and its subsidiar ies and affiliat es. 4104